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本科毕业论文外文参考文献译文及原文学院经济与贸易学院专业经济学（贸易方向）年级班别2007级 1 班学号3207004154学生姓名欧阳倩指导教师童雪晖2010 年 6 月 3 日目录1 外文文献译文（一）中国银行业的改革和盈利能力（第1、2、4部分） (1)2 外文文献原文（一）CHINA’S BANKING REFORM AND PROFITABILITY（Part 1、2、4） (9)1概述世界银行（1997年）曾声称，中国的金融业是其经济的软肋。

当一国的经济增长的可持续性岌岌可危的时候，金融业的改革一直被认为是提高资金使用效率和消费型经济增长重新走向平衡的必要（Lardy，1998年，Prasad，2007年）。

事实上，不久前，中国的国有银行被视为“技术上破产”，它们的生存需要依靠充裕的国家流动资金。

但是，在银行改革开展以来，最近，强劲的盈利能力已恢复到国有商业银行的水平。

但自从中国的国有银行在不久之前已经走上了改革的道路，它可能过早宣布银行业的改革尚未取得完全的胜利。

此外，其坚实的财务表现虽然强劲，但不可持续增长。

随着经济增长在2008年全球经济衰退得带动下已经开始软化，银行预计将在一个比以前更加困难的经济形势下探索。

本文的目的不是要评价银行业改革对银行业绩的影响，这在一个完整的信贷周期后更好解决。

相反，我们的目标是通过审查改革的进展和银行改革战略，并分析其近期改革后的强劲的财务表现，但是这不能完全从迄今所进行的改革努力分离。

本文有三个部分。

在第二节中，我们回顾了中国的大型国有银行改革的战略，以及其执行情况，这是中国银行业改革的主要目标。

第三节中分析了2007年的财务表现集中在那些在市场上拥有浮动股份的四大国有商业银行：中国工商银行（工商银行），中国建设银行（建行），对中国银行（中银）和交通银行（交通银行）。

引人注目的是中国农业银行，它仍然处于重组上市过程中得适当时候的后期。

第四节总结一个对银行绩效评估。

外文文献翻译译稿和原文

外文文献翻译译稿1卡尔曼滤波的一个典型实例是从一组有限的，包含噪声的，通过对物体位置的观察序列（可能有偏差）预测出物体的位置的坐标及速度。

在很多工程应用（如雷达、计算机视觉）中都可以找到它的身影。

同时，卡尔曼滤波也是控制理论以及控制系统工程中的一个重要课题。

例如，对于雷达来说，人们感兴趣的是其能够跟踪目标。

但目标的位置、速度、加速度的测量值往往在任何时候都有噪声。

卡尔曼滤波利用目标的动态信息，设法去掉噪声的影响，得到一个关于目标位置的好的估计。

这个估计可以是对当前目标位置的估计（滤波），也可以是对于将来位置的估计（预测），也可以是对过去位置的估计（插值或平滑）。

命名[编辑]这种滤波方法以它的发明者鲁道夫.E.卡尔曼（Rudolph E. Kalman）命名，但是根据文献可知实际上Peter Swerling在更早之前就提出了一种类似的算法。

斯坦利。

施密特（Stanley Schmidt）首次实现了卡尔曼滤波器。

卡尔曼在NASA埃姆斯研究中心访问时，发现他的方法对于解决阿波罗计划的轨道预测很有用，后来阿波罗飞船的导航电脑便使用了这种滤波器。

关于这种滤波器的论文由Swerling（1958）、Kalman (1960)与Kalman and Bucy（1961）发表。

目前，卡尔曼滤波已经有很多不同的实现。

卡尔曼最初提出的形式现在一般称为简单卡尔曼滤波器。

除此以外，还有施密特扩展滤波器、信息滤波器以及很多Bierman, Thornton开发的平方根滤波器的变种。

也许最常见的卡尔曼滤波器是锁相环，它在收音机、计算机和几乎任何视频或通讯设备中广泛存在。

以下的讨论需要线性代数以及概率论的一般知识。

卡尔曼滤波建立在线性代数和隐马尔可夫模型（hidden Markov model）上。

其基本动态系统可以用一个马尔可夫链表示，该马尔可夫链建立在一个被高斯噪声（即正态分布的噪声）干扰的线性算子上的。

系统的状态可以用一个元素为实数的向量表示。

国际贸易对碳排放的影响外文文献翻译中英文

外文文献翻译(含：英文原文及中文译文)英文原文The effects of international trade on Chinese carbon emissionsB Wei ，X Fang ，Y WangAbstractInternational trade is an important impact factor to the carbon emissions of a country. As the rapid development of Chinese foreign trade since its entry into the WTO in 2002, the effects of international trade on carbon emissions of China are more and more significant. Using the recent available input-output tables of China and energy consumption data, this study estimated the effects of Chinese foreign trade on carbon emissions and the changes of the effects by analyzing the emissions embodied in trade between 2002 and 2007. The results showed a more and more significant exporting behavior of embodied carbon emissions in Chinese international trade. From 2002 to 2007, the proportion of net exported emissions and domestic exported emissions in domestic emissions increased from 18.32% to 29.79% and from 23.97% to 34.76%, respectively. In addition, about 22.10% and 32.29% of the total imported emissions were generated in processing trade in 2002 and 2007, respectively, which were imported and later exported emissions. Although, most of the sectors showed a growth trend in imported and exportedemissions, sectors of electrical machinery and communication electronic equipment, chemical industry, and textile were still the biggest emission exporters, the net exported emissions of which were also the largest. For China and other developing countries, technology improvement may be the most favorable and acceptable ways to reduce carbon emissions at present stage. In the future negotiations on emissions reduction, it would be more fair and reasonable to include the carbon emissions embodied in international trade when accounting the total emissions of an economy. Keywords: input-output analysis, carbon emissions, international trade, ChinaIntroductionGlobal warming has been considered an indisputable fact. The main reason is that the warming of the global climate system is due to the continuous increase in the concentration of greenhouse gases in the atmosphere, the result of human activities (IPCC, 2007). In order to avoid the possible negative impact on human society's global warming, a series of measures have been taken to reduce global greenhouse gas emissions to slow down global warming. However, around the CO2 emission reduction and the future allocation of carbon emission rights, the game plays a different interest group.With the development of globalization, the impact on the international trade of the environment is becoming more and moresignificant, including the potential impact of carbon emissions from geographical relocation. Many researchers estimate that it is reflected in international trade in certain countries as well as in the world economy (Wykoff and Rupp, carbon emissions in 1994; Schaefer and Lealdesa, 1996, Machado et al., 2001 Year; Munksgaard, Peder and Sen, 2001; Ahmed and Wykov, 2003; Sanchez-Chóliz and Duarte, 2004; Peters and Hess, 2006, 2008; Mäenpää et al, 2007; Keman et al., 2007). The general conclusion is that in a more open economy, the impact of large foreign trade on the carbon emissions of a country. In addition, all these studies have pointed out that import and export trade cannot ignore a relatively open economy; otherwise, energy and carbon emissions figures may be seriously distorted by this economy (Machado et al., 2001). In terms of total volume, the value of China’s trade surplus increased from US$30.43 billion in 2002 to US$261.83 billion in 2007 (National Bureau of Statistics, 2008). The rapid growth of China’s foreign trade will have a significant effect on China’s carbon emissions.As one of the countries with the highest carbon emissions, China is facing increasing pressure to reduce emissions. However, China is also a big country in international trade. The rapid development of China’s economy has led to steady growth in foreign trade. From 1997 to 2002, China’s total import and export value increased by an average annual growth rate of 14.35%. Since joining the World Trade Organization, theaverage annual growth rate of China’s trade has jumped to 28.64%. From 2002 to 2007, the value of exports compared with 2002, it increased by 2.7 times in 2007 to reach US$1.2177.8 billion. Imports also soared to US$955.95 billion in 2007, which was 2.2 times higher than the 2002 imports. In terms of total volume, the value of China’s trade surplus increased from US$30.43 billion in 2002 to US$261.83 billion in 2007 (National Bureau of Statistics, 2008). The rapid growth of China’s foreign trade will have a significant effect on China’s carbon emissions.However, quantitative assessment of the impact of China's international trade in energy use and carbon emissions has only recently begun. Estimates from the IEA (2007) show that China's domestic production and export of energy-related carbon dioxide emissions account for 34% of total emissions, and if it is used in 2004, the weighted average carbon intensity of commodity countries imported from China is estimated. China's net exports of EM-rich CO2 may be more than 17% of total emissions in 2004 (Levin, 2008). Using a single-area input-output model, Pan et al. (2008) estimated that their production of energy and emissions in 2002 accounted for 16% and 19% of China’s net exports of primary energy consumption, respectively, in 2002. In the input-output analysis, China reported that the discharge volume of pre-grid discharges to the United States accounted for about 5%. Weber et al. (2008), ESTI mating production exported from China's carbon dioxide emissions from1987 to 2005. In 2005, about one-third of China's emissions were due to production exports, and this proportion has risen from 12% in 1987 to 21% in 2002. In developed countries, consumption is driving this trend. Wei et al.'s estimation (2009a) also found that the presence of emissions in China's economy in 2002 reflected significant export behavior; in addition, subsequent exports (processing trade played by EMIS--) were total imports of 20 %the above. In addition, using a multi-area input-output model, Peters and Hewei (2008) also found that export emissions represented 24.4% of China's domestic emissions, and the proportion of imports in 2001 was only 6.6%. A similar study by Atkinson et al. (2009) also shows that China is a net exporter of carbon emissions in international trade. In recent years, using ecological input-output based on physical access programs, MOD-Y eling, Chen and Chen (2010) estimated that in 2007 China's export of carbon dioxide emissions and total energy were respectively 32.31% and 33.65% of total emissions.Both the United States and European countries are major importers of China’s export carbon emissions. Using the economic input-output life cycle assessment software, Ruihe Harris (2006) found that about 7% of China’s carbon dioxide emissions from exports to the United States during the period of 1997-2003 were produced by 14% of the total; the US’s CO2 emissions will At 3%-6%, if increased imports from Chinahave been produced in the United States. AP-walking a similar approach, Lee Hewitt found that bilateral trade between the United Kingdom and China (2008) produced about 4% of CO2 emissions. In 2004, China's CO2 emissions were for the UK market to produce goods and the UK trade decreased. About 11%. Weber et al. (2008) also found that most of China’s recent export emissions went to developed countries, approximately 27% of the United States, 19% of the EU-27, and 14% of the remaining Annex B countries, mainly Japan and Australia. And New Zealand. Recently, Xu et al. (2009) studied the impact of energy consumption and exhaust emissions on the environment. From 2002 to 2007, the use of environmental input-output analysis and adjustment of bilateral trade data reflected trade in the East (from China to the United States). Zhang (2009) has also obtained similar results. Energy and CO2 account for about 12% and 17% of China's energy consumption, and China's CO2 emissions are 8% and 12%, respectively.Although China's international trade is a meaningful research on carbon emissions, further related research is necessary because of the rapid development of China's foreign trade, especially the development of processing trade. According to statistics (National Bureau of Statistics, 2008), the export share of processing trade has been more than 50% of total exports since 1996. In 2002 and 2007, the share of processing trade reached 55.26% and 50.71%, which will be processing trade. Thenecessary distinction between the impact of general trade and China's carbon emissions.Since China's input-output table is only 5 years, we have chosen from 2002 (entry to the WTO) to 2007 (the latest issue), and China's international trade input-output table has impact on carbon emissions with the view of the last requirement of this paper. Influence changes. In addition, we distinguish between domestic processing trade and import investment in the assessment of production processes (import emissions and re-exports), which will help us to further understand the impact of international trade on emissions status. In this study, we tried to answer three questions: 1) What is the net emissions generated by foreign trade in China as a big country's foreign trade? 2) China from 2002 to 2007, International How does trade affect carbon emissions? 3) From 2002 to 2007, which departments were the major emitters of China's import and export trade and their roles?Uncertainty in the calculation of carbon emissionsThe calculation of emissions from China's trade reflects a certain degree of uncertainty. One is that the input-output analysis itself has many inherent uncertainties (more discussion in Lenzen, 2001). Based on an input-output table for China's single region, it allows us to obtain a relatively accurate assessment of the emissions that are reflected in China's exports, but this error may be more pronounced when estimatingthe emissions of goods and services exported to China. (Lenzen , 2001; Lenzen et al., 2004). Another important factor of uncertainty is that the calculations come from different regions, which may underestimate the method of importing the carbon intensity factor that is reflected in the import of larger proportion of finished product producing countries and tertiary industries, and the smaller proportion of secondary industries. In addition, the method of pro-grade introduction of the column will inevitably result in some errors in order to obtain a matrix from the inlet of the original import and export table.At present, for reasons of data availability, we cannot fully quantify the accuracy of our calculations, but preliminary estimates suggest that the use of more accurate data results from research will not significantly change the conclusions of this analysis. These restrictions will be improved through the use of multi-zone import and export tables and out-of-zone more detailed industry carbon intensity and sector-to-sector production processes in the future for detailed analysis.Understand the impact of international trade on carbon emissions in ChinaFrom 2002 to 2007, the impact of foreign trade on China’s carbon emissions has greatly expanded. It may be largely related to two factors. The first is the coal-based energy consumption structure. The secondary industry-based production structure will maintain high domestic energyintensity. In 2002, the coal consumption exchange was only 66.3% of the total energy consumption. The 44.8% of China's gross domestic product (GDP) is due to the secondary industry in 2002 (National Bureau of Statistics, 2008). In 2007, related stock prices rose as high as 69.5% and 48.6%, respectively, which will lead to the fact that the unit exports are higher than the carbon emissions reflected in unit imports. The second factor, which may be a more important factor, is the rapid growth of export trade. From 2002 to 2007, China’s exports increased by 246.80%, while imports increased by 199.97% (National Bureau of Statistics, 2008). Export growth is significantly higher than imports, which may lead to a sharp increase in net exports. Decomposition analysis using input and output structures, Liu et al. (2010) also found that the total export expansion of export and energy-intensive products tends to expand, reflecting the export of energy from 1992 to 2005, but the improvement and change of energy efficiency in the primary energy consumption structure can offset part of the impact on export energy. The above driving force is implemented.Although, based on the coal-based energy consumption structure, the carbon dioxide emissions produced by the secondary industry-based production structure, the more important role, it may be difficult for China to adjust because of its endowment characteristics, and in a very short time Its structural characteristics and its current economicdevelop ment stage. In addition, the expansion of China’s foreign trade, including the expansion of the trade surplus, is mainly the result of the market economy’s maximizing its comparative advantage. The development-replacement of China's economy not only provided many of the world's goods and services, but also reduced the nation's production-based relative costs in developed countries. China’s foreign trade has always played an important role in the development of the world economy, due to its huge market, stable government system and abundant cheap labor. Therefore, it can be argued that at the current stage, for China's better methods to reduce the impact of international trade on national or global CO2 emissions should be to improve its production technology, reduce the intensity of energy consumption as a whole, not only to control China The amount of foreign trade. In addition, the imported goods from China should take part in China's carbon emission responsibilities, because the CON-consumer demand of foreign consumers has generated a large amount of China's carbon emissions, especially for consumers in developed countries.ConclusionDespite some uncertainties in this study, most areas produced from the details of the data, we can conclude that international trade has a significant impact on China's carbon emissions, and changed the impact of time on going. Compared with 2002 emissions, domestic exportemissions in 2007 increased from 267.07 MTC to 718.31 MTC, with a speed increase of over 160%; net exports also increased correspondingly, from 204.08 MTC up to 615.65 MTC, over 200% growth rate Now. From 23.97% in 2002, the share of domestic emissions from domestic emissions jumped to 34.76% in 2007. The share of pre-net transplants that exceeded domestic emissions also rose from 18.32% in 2002 to 29.79% in 2007. The results show that more and more significant net export behaviors of implied carbon emissions exist in China's economy and processing trade have more and more significant effects on carbon emissions.Regardless of the emissions of imported emissions or exports, most industries showed a growth trend in 2007. Compared with 2002, emissions although the sectoral emissions have changed for the entire economy from 2002 to 2002, The impact, of which the largest percentage of imported major department or China's export emissions remain unchanged. The largest import emissions (all or actual imports) come from the industries of electrical machinery and communications electronics, chemicals, smelting and rolling plus metals. Electrical machinery and communications electronics equipment, chemicals, textiles and other sectors are the largest emitters of exports, net exports of which are also the largest. Technological progress may be the most favorable and acceptable way for China and other developing countries toreduce their carbon emissions. Considering that the world’s largest carbon emissions and the recent increase in emissions are in developing countries, the historical responsibility for the current responsibilities, developed countries should also take more efforts to help developing countries reduce their carbon emissions. Economic growth through technical assistance And financial support. In the car's list of future emissions reductions, which include the total economic output, the carbon emissions reflected in international trade will be fair and reasonable.中文译文国际贸易对中国碳排放的影响: 一份具有经验性的分析作者：B Wei ，X Fang ，Y Wang摘要国际贸易是一个国家碳排放量重要的影响因素,自2002年加入世贸组织,中国对外贸易的快速发展对碳排放的影响越来越显著。

外文资料翻译

毕业设计外文资料翻译系别：管理系专业：班级：姓名：学号：外文出处：<<ENGINEERING MANAGEMENT PROFESSION>>工程管理专业附件：1、外文原文；2、外文资料翻译译文。

指导教师评语：签字：年月日1、外文原文；Scheduling systems and their selectionScheduling systemsNow we are ready to discuss the various methods for scheduling capital construction projects that are available. The two basic methods that will be discussed are bar charts and logic-diagram-based schedules. Both methods are used extensively, and sometimes interchangeably, in project and construction work. Each method has its advantages and disadvantages. Knowing when to select the correct method is half the battle in successfully making and controlling your project schedule.Bat chartsThe forerunner to the bar chart was developed by two industrial engineers, Frederick W. Taylor and Henry L. Gantt, for scheduling production operations during World War I. the name “Gantt chart” is still in use today to designate certain types of bar charts. It was sometime after World War I that bar-charting was adapted to the scheduling of construction projects.Bar charts are the simplest from of scheduling and have been in use the longest of any of the systems we have available. They offer the advantage of being cheap and simple to prepare; they are easy to read and update, and they are readily understood by anyone with a basic knowledge of the capital projects business. They are still in wide use today, even as a final product of the computerized CPM scheduling system. The main disadvantage of the bar chart is its inability to show enough detail to cover all the activities on larger, complex projects. On large projects, the number of pages required to bar- chart the project becomes cumbersome, and interrelation of work activities becomes difficult to follow from page to page.As the size and complexity of projects grew in the late fifties and sixties in the 20th century, finishing projects late became the rule rather than the exception. Late finishes, along with their associated cost overruns, caused increased pressure on owners and contractors to develop improved scheduling techniques. Now when we try to schedule a larger project in that sort of detail with bar charts, we quickly lose most of the advantages that we listed earlier. The schedule becomes unwieldy and difficult to interpret, and we run the risk of losing control of the project time plan.Logic- based schedulesFortunately, on the same time, the network schedule and the computer came on thecapital projects scene. We now had a tool available to make the many repetitive calculations for the earl and late start dates, and a place to store and sort the data needed to control a large number of work activities.In the late 1950s the U.S. Navy and the Du Pont Company concurrently developed two different logic-diagram-based scheduling systems at about the same time. The Naty’s system was called PERT, for Program Evaluation and Review Technique. Its first successful application was on the Polaris Missile Program. At about the same time, Du Pont first successfully used their critical path method (CPM) of logic diagram scheduling on several new petrochemical plants.Other owners and contractors lost no time in adapting the new scheduling methods to their projects in order to improve their timely completion performance. The CPM system was somewhat simpler than the PERT method, so it soon became the system favored for use on commercial and industrial capital projects. The KISS principle triumphed again! The basic logic-diagraming principles developed in the 1960s are still and graphical output. In the 1980s, the development of the relatively low-cost PC made the use of the CPM system possible for even the smallest companies.Shortly after the introduction of the PERT/CPM systems in the early sixties, the pendulum swung from simple bar charting to the side of overly detailed, computerized schedules. That didn’t work out as well as the early success with the systems had seemed to indicate it would. If a little bit of CPM was good, more had to be better! Everyone promptly defied the kiss principle and started to schedule in too much detail on each activity. The result was reams and reams of computer output that virtually inundated many untrained people.Most of the construction managers and field schedulers of that period were entrepreneurial craft people who had worked themselves up through the ranks. In many cases they were literally untrainable in the new technology of computerized CPM scheduling. Fortunately, some of the users of the newly developed techniques remembered the KISS principle and developed some easy-to-use systems. Several good mainframe programs came onto the market, including McDonnell Automation’s MSCS system, Metier’s Artemis system, and IBM’s PCS system. As computer capacity and new software bloomed , the programs developed and improved rapidly over the next 20 years.The rapid development of low-cost PC hardware and software has now virtually taken over the CPM capital projects scheduling market. Mainframe computers are now required only on the very largest and most complex projects, those whose logistics demands are too great for memory capabilities of the PC.Comparison and selection of scheduling systemsEvaluating the advantages and disadvantages of bar charts versus CPM allows us to select the most effective system for a given project. It also leads us to some simple rules that are applicable to the selection.Advantages of CPMA. Handling complex projectsThe number-one advantage of the CPM system is its ability to handle many work activities on complex projects with ease. Let me introduce a word of caution on that point: don’t fall into the trap of using more activities than necessary, just because it is easy to do so. You risk getting your schedule bogged down in too much detail, which Makes it harder to use and costs more money to operate. Remember , that's the same trap that almost killed the CPM system in its early days ! One way to avoid the problem is to break out some of the less complicated scheduling areas and use bar charts for them .They could be offsite areas such as small office buildings ,warehouses ,tank farms, and roads . A blend of the two systems often results in a simpler and more effective overall project schedule.B .Dry Run of the projectsAnother outstanding advantage of CPM is the intangible benefit of forcing the project team to dissect the project into all of its working parts. This forces the early analysis of each work activity. The CPM schedule an in checking the resulting logic diagram.The actual scheduling phase, such as calculating the early an late start dates and the associated float, is best left to the scheduling technicians and the computer. It is usually necessary to run the fist pas of the schedule several times, to test and debug the logic diagram before the final version is ready for review and approval.C. Beneficial Output SortsThe large menu of output sorts is another big advantage of a computerized CPM schedule. It allows the various interest members of the construction team to order the output sort best suited to their work. Most CPM programs will yield a sort menu as follows:(1)Total float per activity(2)Limited look-ahead sorts(3)Critical-path sort(4)Critical-equipment sort(5)Project-milestone sort(6)Bar-chat printout(7)Human resource levelingMost CMs, for example, will find the sorts by total float and by milestone most valuable for their needs. The total -float sort starts with the low-float(most critical)work activities listed first for immediate attention. The less critical high-float items show up later on the list. By using the period look- ahead sorts, one can also home in on specific time period, A 30-,60-,90-day look ahead sort will list only those critical items that will occur in the next 30,60,90 days. Material control people find the critical-item sort more convenient in tracking their required delivery dates and actual progress are fed in to the computer,, revised printouts quickly reflect the delivery changes and their effect on the field schedule. Field people usually find that the key-milestone-date sort better suits their needs.Most CPM scheduling software even delivers a bar-chart printout, which is most convenient for upper management and reporting purposes in reviewing project progress. Simplified bar charts are usually included in the progress reports to give a graphic view of actual progress against the schedule.The human resource leveling can level peak personnel requirements, which occur during the project's design and construction phases. By taking advantage of the available during the project's design and construction phases. By taking advantage of the available flat and rescheduling the start of noncritical activities, it's possible to shave personnel peaks. Leveling the personnel requirements leads to more effective use of the project's human resources. This option is invaluable for smoothing out craft manpower peaks in key areas of the work. Judicious use of the early and late start dates can also keep subcontractors from getting in each other's way.D. Convenient Schedule ControllingOn smaller projects, a simple time -scaled bar chart might be used in the progress report. The rapid turnaround of data by the computer also allows the project team to perform what-if exercises with the logic diagram. When scheduling problems arise, the project team can try alternative solutions by reworking elapsed times for problem activities. This generates new early and late start dates that can be shifted to improve the critical path. The computer calculates a new critical path in a matter of seconds, with immediate access to the new output data right there on the computer screen.A CPM/computer system also simplifies recycling the schedule. Recycling becomes necessary whenever schedule deviations grow to a point at which some of the intermediate goals are in jeopardy. Recycling involves revising any target dates that may have slipped beyond repair, perhaps because a significant change in scope has occurred. Exercising some what-if options should allow you to obtain the scheduling-revision option best suited to keeping the project on schedule.Disadvantages of CPMThere are only a few disadvantages to using the CPM method for project scheduling, and even these can be avoided with proper attention from the CM. However, overlooking any of the disadvantages can scuttle your effects to control the project schedule!It's extremely important that your key field people be trained in CPM techniques. That includes all levels from the design group to procurement, and through the construction management team. Remember the story about construction managers trashing the CPM/computer printouts in earlier days!I don't recommend controlling a large project with only a newly trained crew, or usinga new software system without running your old scheduling system in parallel, at least until the new system has been prove to work. If the new system breaks down for any reason, you will be without any means of controlling the end date on the project.The cost of running a CPM schedule is likely to be higher than that of using bar charts, particularly on smaller projects. That was especially true of running the CPM schedule on a mainframe computer. In recent years the relatively modest cost of PC hardware, software, and training has enabled us to expense off that cost for computerized CPM scheduling on a medium-to-large project. It might take several small-sized projects to cover the cost of a PC scheduling system.The cost of the training could be the sleeper in the scheduling cost budget, depending on the experience and computer literacy of your project people. But regardless of the cost, training is the linchpin of the whole system, so don’t ignore it.The real savings in using a PC-computerized schedule is that it will generate a good deal more data than is possible with bar charts. That means the unit cost of the data is low. However if the data is not being used (or worse, is being improperly used!), you will not be getting your money’s worth. It is up to the CM to see that the computerized schedule output is used in a cost-effective manner.The cost effectiveness of using CPMIt is difficult to accurately quantify the cost effectiveness of using CPM scheduling systems on capital projects. First, there is no absolute measure of the time saved by using CPM versus bar charts. Second, the value of the time saved must be balanced against the value to the owner of having earlier access to the facility. Any comparisons of that nature have proved to be highly speculative and difficult to verify.Most owners and contractors accept any additional cost of using CPM scheduling systems as a way to improve the odds of completing their projects on time. Those who do not believe that CPM saves money and ensures a project’s earlier completion date cancontinue to use manual bar-charting with reasonable hope of success.O’Brien’s book, CPM in Construction Management, contains a chapter on costs and some expected saving from using CPM. On average , the cost of applying a CPM system to a project is about 0.5 percent of the total facility cost. The major cost areas for using the system are schedules’ time , software cost ,and computer time.CMs must be aware of the type of scheduling system that is being proposed for their projects, so they can budget funds to cover the cost. Small projects can be done with a part-time scheduler; medium-size projects need at least one person full-time; and larger project require two or more schedulers to handle the workload. Include all computer costs (including necessary training)in the project budget. Be especially carefully if a mainframe computer is used.Advantages of bar-chart schedulesAs I said earlier, bar charts are inexpensive to produce and are easily understood by people with a minimum of scheduling training. I heartily recommend them for small, less complex projects, as being suitable and cost-effective. The more comprehensive CPM system is often too complicated, and represents unnecessary overkill when used on small projects. There are some good PC-based CPM programs available for scheduling a series of small projects, which draw from the same resource pool.The only thing that threatens the economic advantages of using bar charts on small projects has been the advent of PCs, Along with less complicated scheduling software. It is easy to temped into the use of a PC, with the construction manager or engineer acting as the project scheduler. That can be all right if the designated scheduler does the scheduling work in his or her free time. IF ,however, the project leader gets so involved in running the CPM schedule that he or she lets he rest of the rest of the project direction go its own way, the project is doomed to failure.Disadvantages of bar-chart schedulesBar charts have only a limited ability to show many detailed work activities and their associated interactions, They become bulky and unwieldy on larger project with as few as 100 activities.Bar charts cannot show clearly the interaction between early start and late finish dates of activities and the resulting float of noncritical activities. There is no clear identification of the critical path through the project that appears with the CPM system. Also, it’s impossible to develop the wealth of scheduling detail with a bar chart like that developed and manipulated with the CPM system. With bar charts there are no concise information sorts as with the CPM.Computer versus manual scheduling methodsThe major factors in selecting computer over manual scheduling methods are project size and complexity. Small projects are best done manually, since good time control is possible at low cost. However ,a complex plant turnaround project, with a relatively low budget but working three shifts on a tight schedule, definitely warrants a computerized CP approach.On larger projects using CPM, computer operation is a must if the many repetitive critical path calculations are to be performed in short time. Manipulating and sorting the expanded database of project information is well worth the additional expense if the system is properly applied. The arrival of PCs and minicomputers, with their associated scheduling software, has brought the cost well within acceptable limits. The simpler operations of the PC-based systems have also reduced the cost of the necessary CPM training.Scheduling system selectionOur discussion of the advantages and disadvantages of the available scheduling systems should allow us to develop guidelines for selecting an effective scheduling system. The selection involves such factors as:1.Size and complexity of project2.Scope of services required3.Sophistication of user organizations(i.e., client, field organization, subcontractors,and so on )4.Available scheduling systems5.Scheduling budget6.Client preference7.Mixing schedule and costSize of projectWe have already discussed this point earlier. The rule of thumb is bar charts and manual systems for small projects, and computerized CPM for medium-size and lager projects. The level of sophistication of the system tends to become greater as the projects become larger.Complexity of projectEven small complex projects can make good use of computerized CPM schedules, if the fewer activities take place in a very short time span. An example is a plant turnaround worth﹩1 million or less, with only 10 days to do it. On the other hand, a﹩1 million project with a 12-month schedule might not warrant a computerized CPM schedule.Scope of servicesFull-scope design, procurement and construction projects lend themselves to more complex scheduling methods, because of the extra interfaces among the many design, procurement, and construction activities. A project involving just one of these macroactivities could effectively controlled with a less sophisticated and less costly system.Sophistication of user organizationsThe sophistication of user organizations is probably the most overlooked factor in selecting a scheduling system. Often, the need to produce a full-blown CPM schedule exists. However, one key project group may not be experienced enough in CPM to properly interpret their part in it. Assure yourself that the failure of that group to perform properly will not defeat the propose scheduling method.An example would be working with a client in a developing country. If the client’s people lacked system, they might not feel comfortable using it to track job progress. Also, they might not keep their contributions to the project on schedule/. Another example would be an inexperienced construction force not being able to sue the output of the CPM scheduling system, such as we discussed earlier.The worst possible case would occur if the CM were not versed in the selected scheduling system! That underscores the need for present-day CMs to stay current on the latest CPM scheduling methods available in their companies and the marketplace. I definitely recommend that you success-oriented CMs do further, more in- depth study of logic-based scheduling than I have presented here.If there is a shortage of CPM know-how in your organization, it is possible to hire a CPM consultant to handle your project scheduling. At least one member of your team, however, should have enough knowledge of the work. That is the best way to ensure that the resulting schedule will be effective for your project.Existing company systems availableThe availability of company systems is important, because we want to use a system that has been in use within the organization, and that has been thoroughly tested on prior similar projects. Introducing a new system on a project often causes more problems than it solves. As an owner’s project manager, you would do well to assure yourself that the contractor is proficient in the system before allowing its use on your project. It is also not a good idea to force the use of your corporate standard system on the contractor just because your organization is familiar with it. A much wiser curse is to train your people in the use of the contractor’s scheduling system.Scheduling budgetIf the field indirect cost budget dose not allow sophisticated scheduling method, you are going to come up short of money. Most computerized CPM scheduling costs have a tendency to grow and overrun their budgets. A common problem is job stretch-out, which increase the schedule cycles, which in return runs up the scheduling personnel hours and computer time. A factual estimate of the total cost of the proposed scheduling system is needed if an effective system for the project to be selected.Client preferenceOwners who want computerized CPM schedules, and who are willing to pay for them, are entitled to have them. If the owner does not specify a preference for a scheduling system, some common ground for developing a cost-effective system will have to be found.In recent years most federal government contracts have required adherence to a strict contractual standard, calling for use of CPM schedule-control and reporting,. Careful attention must be given to investigating the latest scheduling requirements for any federal work on which you may be proposing.2、外文资料翻译译文。

外文翻译原文

DOI10.1007/s10711-012-9699-zORIGINAL PAPERParking garages with optimal dynamicsMeital Cohen·Barak WeissReceived:19January2011/Accepted:22January2012©Springer Science+Business Media B.V.2012Abstract We construct generalized polygons(‘parking garages’)in which the billiard ﬂow satisﬁes the Veech dichotomy,although the associated translation surface obtained from the Zemlyakov–Katok unfolding is not a lattice surface.We also explain the difﬁculties in constructing a genuine polygon with these properties.Keywords Active vitamin D·Parathyroid hormone-related peptide·Translation surfaces·Parking garages·Veech dichotomy·BilliardsMathematics Subject Classiﬁcation(2000)37E351Introduction and statement of resultsA parking garage is an immersion h:N→R2,where N is a two dimensional compact connected manifold with boundary,and h(∂N)is aﬁnite union of linear segments.A parking garage is called rational if the group generated by the linear parts of the reﬂections in the boundary segments isﬁnite.If h is actually an embedding,the parking garage is a polygon; thus polygons form a subset of parking garages,and rationals polygons(i.e.polygons all of whose angles are rational multiples ofπ)form a subset of rational parking garages.The dynamics of the billiardﬂow in a rational polygon has been intensively studied for over a century;see[7]for an early example,and[5,10,13,16]for recent surveys.The defi-nition of the billiardﬂow on a polygon readily extends to a parking garage:on the interior of N the billiardﬂow is the geodesicﬂow on the unit tangent bundle of N(with respect to the pullback of the Euclidean metric)and at the boundary,theﬂow is deﬁned by elastic reﬂection (angle of incidence equals the angle of return).Theﬂow is undeﬁned at theﬁnitely many M.Cohen·B.Weiss(B)Ben Gurion University,84105Be’er Sheva,Israele-mail:barakw@math.bgu.ac.ilM.Cohene-mail:comei@bgu.ac.ilpoints of N which map to‘corners’,i.e.endpoints of boundary segments,and hence at thecountable union of codimension1submanifolds corresponding to points in the unit tangentbundle for which the corresponding geodesics eventually arrive at corners in positive or neg-ative time.Since the direction of motion of a trajectory changes at a boundary segment viaa reﬂection in its side,for rational parking garages,onlyﬁnitely many directions of motionare assumed.In other words,the phase space of the billiardﬂow decomposes into invarianttwo-dimensional subsets corresponding toﬁxing the directions of motion.Veech[12]discovered that the billiardﬂow in some special polygons exhibits a strikingly he found polygons for which,in any initial direction,theﬂow is eithercompletely periodic(all orbits are periodic),or uniquely ergodic(all orbits are equidistrib-uted).Following McMullen we will say that a polygon with these properties has optimaldynamics.We brieﬂy summarize Veech’s strategy of proof.A standard unfolding construc-tion usually attributed to Zemlyakov and Katok[15]1,associates to any rational polygon Pa translation surface M P,such that the billiardﬂow on P is essentially equivalent to thestraightlineﬂow on M P.Associated with any translation surface M is a Fuchsian group M,now known as the Veech group of M,which is typically trivial.Veech found M and P forwhich this group is a non-arithmetic lattice in SL2(R).We will call these lattice surfaces and lattice polygons respectively.Veech investigated the SL2(R)-action on the moduli space of translation surfaces,and building on earlier work of Masur,showed that lattice surfaces haveoptimal dynamics.From this it follows that lattice polygons have optimal dynamics.This chain of reasoning remains valid if one starts with a parking garage instead of apolygon;namely,the unfolding construction associates a translation surface to a parkinggarage,and one may deﬁne a lattice parking garage in an analogous way.The arguments ofVeech then show that the billiardﬂow in a lattice parking garage has optimal dynamics.Thisgeneralization is not vacuous:lattice parking garages,which are not polygons,were recentlydiscovered by Bouw and Möller[2].The term‘parking garage’was coined by Möller.A natural question is whether Veech’s result admits a converse,i.e.whether non-latticepolygons or parking garages may also have optimal dynamics.In[11],Smillie and the sec-ond-named author showed that there are non-lattice translation surfaces which have optimaldynamics.However translation surfaces arising from billiards form a set of measure zero inthe moduli space of translation surfaces,and it was not clear whether the examples of[11]arise from polygons or parking garages.In this paper we show:Theorem1.1There are non-lattice parking garages with optimal dynamics.An example of such a parking garage is shown in Fig.1.Veech’s work shows that for lattice polygons,the directions in which all orbits are periodicare precisely those containing a saddle connection,i.e.a billiard path connecting corners ofthe polygon which unfold to singularities of the corresponding surface.Following Cheunget al.[3],if a polygon P has optimal dynamics,and the periodic directions coincide with thedirections of saddle connections,we will say that P satisﬁes strict ergodicity and topologicaldichotomy.It is not clear to us whether our example satisﬁes this stronger property.As weexplain in Remark3.2below,this would follow if it were known that the center of the regularn-gon is a‘connection point’in the sense of Gutkin,Hubert and Schmidt[8]for some nwhich is an odd multiple of3.Veech also showed that for a lattice polygon P,the number N P(T)of periodic strips on P of length at most T satisﬁes a quadratic growth estimate of the form N P(T)∼cT2for a positive constant c.As we explain in Remark3.3,our examples also satisfy such a quadratic growth estimate.1But dating back at least to Fox and Kershner[7].Fig.1A non-lattice parkinggarage with optimal dynamics.(Here 2/n represents angle 2π/n )It remains an open question whether there is a genuine polygon which has optimal dynam-ics and is not a lattice polygon.Although our results make it seem likely that such a polygon exists,in her M.Sc.thesis [4],the ﬁrst-named author obtained severe restrictions on such a polygon.In particular she showed that there are no such polygons which may be constructed from any of the currently known lattice examples via the covering construction as in [11,13].We explain these results and prove a representative special case in §4.2PreliminariesIn this section we cite some results which we will need,and deduce simple consequences.For the sake of brevity we will refer the reader to [10,11,16]for definitions of translation surfaces.Suppose S 1,S 2are compact orientable surfaces and π:S 2→S 1is a branched cover.That is,πis continuous and surjective,and there is a ﬁnite 1⊂S 1,called the set of branch points ,such that for 2=π−1( 1),the restriction of πto S 2 2is a covering map of ﬁnite degree d ,and for any p ∈ 1,#π−1(p )<d .A ramiﬁcation point is a point q ∈ 2for which there is a neighborhood U such that {q }=U ∩π−1(π(q ))and for all u ∈U {q },# U ∩π−1(π(u )) ≥2.If M 1,M 2are translation surfaces,a translation map is a surjective map M 2→M 1which is a translation in charts.It is a branched cover.In contrast to other authors (cf.[8,13]),we do not require that the set of branch points be distinct from the singularities of M 1,or that they be marked.It is clear that the ramiﬁcation points of the cover are singularities on M 2.If M is a lattice surface,a point p ∈M is called periodic if its orbit under the group of afﬁne automorphisms of M is ﬁnite.A point p ∈M is called a connection point if any seg-ment joining a singularity with p is contained in a saddle connection (i.e.a segment joining singularities)on M .The following proposition summarizes results discussed in [7,9–11]:Proposition 2.1(a)A non-minimal direction on a translation surface contains a saddle connection.(b)If M 1is a lattice surface,M 2→M 1is translation map with a unique branch point,then any minimal direction on M 2is uniquely ergodic.(c)If M2→M1is a translation map such that M1is a lattice surface,then all branchpoints are periodic if and only if M2is a lattice surface.(d)If M2→M1is a translation map with a unique branch point,such that M1is a latticesurface and the branch point is a connection point,then any saddle connection direction on M2is periodic.Corollary2.2Let M2→M1be a translation map such that M1is a lattice surface with a unique branch point p.Then:(1)M2has optimal dynamics.(2)If p is a connection point then M2satisﬁes topological dichotomy and strict ergodicity.(3)If p is not a periodic point then M2is not a lattice surface.Proof To prove(1),by(b),the minimal directions are uniquely ergodic,and we need to prove that the remaining directions are either completely periodic or uniquely ergodic. By(a),in any non-minimal direction on M2there is a saddle connectionδ,and there are three possibilities:(i)δprojects to a saddle connection on M1.(ii)δprojects to a geodesic segment connecting the branch point p to itself.(iii)δprojects to a geodesic segment connecting p to a singularity.In case(i)and(ii)since M1is a lattice surface,the direction is periodic on M1,hence on M2as well.In case(iii),there are two subcases:ifδprojects to a part of a saddle connec-tion on M1,then it is also a periodic direction.Otherwise,in light of Proposition2.1(a),the direction must be minimal in M1,and hence,by Proposition2.1(b),uniquely ergodic in M2. This proves(1).Note also that if p is a connection point then the last subcase does not arise, so all directions which are non-minimal on M2are periodic.This proves(2).Statement(3) follows from(c).We now describe the unfolding construction[7,15],extended to parking garages.Let P=(h:N→R2).An edge of P is a connected subset L of∂N such that h(L)is a straight segment and L is maximal with these properties(with respect to inclusion).A vertex of P is any point which is an endpoint of an edge.The angle at a vertex is the total interior angle, measured via the pullback of the Euclidean metric,at the vertex.By convention we always choose the positive angles.Note that for polygons,angles are less than2π,but for parking garages there is no apriori upper bound on the angle at a vertex.Since our parking garages are rational,all angles are rational multiples ofπ,and we always write them as p/q,omitting πfrom the notation.Let G P be the dihedral group generated by the linear parts of reﬂections in h(L),for all edges L.For the sake of brevity,if there is a reﬂection with linear part gﬁxing a line parallel to L,we will say that gﬁxes L.Let S be the topological space obtained from N×G P by identifying(x,g1)with(x,g2)whenever g−11g2ﬁxes an edge containing h(x).Topologically S is a compact orientable surface,and the immersions g◦h on each N×{g}induce an atlas of charts to R2which endows S with a translation surface structure.We denote this translation surface by M P,and writeπP for the map N×G P→M P.We will be interested in a‘partial unfolding’which is a variant of this construction,in which we reﬂect a parking garage repeatedly around several of its edges to form a larger parking garage.Formally,suppose P=(h:N→R2)and Q=(h :N →R2)are parking garages.For ≥1,we say that P tiles Q by reﬂections,and that is the number of tiles,if the following holds.There are maps h 1,...h :N→N and g1,...,g ∈G P(not necessarily distinct)satisfying:(A)The h i are homeomorphisms onto their images,and N = h i (N ).(B)For each i ,the linear part of h ◦h i ◦h −1is everywhere equal to g i .(C)For each 1≤i <j ≤ ,let L i j =h i (N )∩h j (N )and L =(h i )−1(L i j ).Then (h j )−1◦h i is the identity on L ,and L is either empty,or a vertex,or an edge of P .If L is an edge then h i (N )∪h j (N )is a neighborhood of L i j.If L i j is a vertex then there is a ﬁnite set of i =i 1,i 2,...,i k =j such that h i s (N )contains a neighborhood of L i j ,and each consecutive pair h i t (N ),h i t +1(N )intersect along an edge containing L i j .V orobets [13]realized that a tiling of parking garages gives rise to a branched cover.More precisely:Proposition 2.3Suppose P tiles Q by reﬂections with tiles,M P ,M Q are the correspond-ing translation surfaces obtained via the unfolding construction,and G P ,G Q are the cor-responding reﬂection groups.Then there is a translation map M Q →M P ,such that the following hold:(1)G Q ⊂G P .(2)The branch points are contained in the G P -orbit of the vertices of P .(3)The degree of the cover is [G P :G Q ].(4)Let z ∈M P be a point which is represented (as an element of N ×{1,...,r })by(x ,k )with x a vertex in P with angle m n (where gcd (m ,n )=1).Let (y i )⊂M Q be the pre-images of z,with angles k i m n in Q .Then z is a branch point of the cover if and only if k i n for some i.Proof Assertion (1)follows from the fact that Q is tiled by P .Since this will be impor-tant in the sequel,we will describe the covering map M Q →M P in detail.We will map (x ,g )∈N ×G Q to πP (x ,gg i )∈M P ,where x =h i (x ).We now check that this map is independent of the choice of x ,i ,and descends to a well-deﬁned map M Q →M P ,which is a translation in charts.If x =h i (x 1)=h j (x 2)then x 1=x 2since (h i )−1◦h j is the identity.If x is in the relative interior of an edge L i j thenπP (x ,gg i )=πP (x ,gg j )(1)since (gg i )−1gg j =g −1i g j ﬁxes an edge containing h (x 1).If x 1is a vertex of P then one proves (1)by an induction on k ,where k is as in (C).This shows that the map is well-deﬁned.We now show that it descends to a map M Q →M P .Suppose (x ,g ),(x ,g )are two points in N ×G Q which are identiﬁed in M Q ,i.e.x ∈∂N is in the relative interior of an edge ﬁxed by g −1g .By (C)there is a unique i such that x is in the image of h i .Thus (x ,g )maps to (x ,gg i )and (x ,g )maps to (x ,g g i ),and g −1i g −1g g i ﬁxes the edge through x =g −1i (x ).It remains to show that the map we have deﬁned is a translation in charts.This follows immediately from the chain rule and (B).Assertion (2)is simple and left to the reader.For assertion (3)we note that M P (resp.M Q )is made of |G P |(resp. |G Q |)copies of P .The point z will be a branch point if and only if the total angle around z ∈M P differs from the total angle around one of the pre-images y i ∈M Q .The total angle at a singularity corresponding to a vertex with angle r /s (where gcd (r ,s )=1)is 2r π,thus the total angle at z is 2m πand the total angle at y i is 2k i m πgcd (k i ,n ).Assertion (4)follows.3Non-lattice dynamically optimal parking garagesIn this section we prove the following result,which immediately implies Theorem1.1: Theorem3.1Let n≥9be an odd number divisible by3,and let P be an isosceles triangle with equal angles1/n.Let Q be the parking garage made of four copies of P glued as in Fig.1, so that Q has vertices(in cyclic order)with angles1/n,2/n,3/n,(n−2)/n,2/n,3(n−2)/n. Then M P is a lattice surface and M Q→M P is a translation map with one aperiodic branchpoint.In particular Q is a non-lattice parking garage with optimal dynamics.Proof The translation surface M P is the double n-gon,one of Veech’s original examples of lattice surfaces[12].The groups G P and G Q are both equal to the dihedral group D n.Thus by Proposition2.3,the degree of the cover M Q→M P is four.Again by Proposition2.3, since n is odd and divisible by3,the only vertices which correspond to branch points are the two vertices z1,z2with angle2/n(they correspond to the case k i=2while the other vertices correspond to1or3).In the surface M P there are two points which correspond to vertices of equal angle in P(the centers of the two n-gons),and these points are known to be aperiodic [9].We need to check that z1and z2both map to the same point in M P.This follows from the fact that both are opposite the vertex z3with angle3/n,which also corresponds to the center of an n-gon,so in M P project to a point which is distinct from z3. Remark3.2As of this writing,it is not known whether the center of the regular n-gon is a connection point on the double n-gon surface.If this turns out to be the case for some n which is an odd multiple of3,then by Corollary2.2(2),our construction satisﬁes strict ergodicity and topological dichotomy.See[1]for some recent related results.Remark3.3Since our examples are obtained by taking branched covers over lattice surfaces, a theorem of Eskin et al.[6,Thm.8.12]shows that our examples also satisfy a quadratic growth estimate of the form N P(T)∼cT2;moreover§9of[6]explains how one may explicitly compute the constant c.4Non-lattice optimal polygons are hard toﬁndIn this section we present results indicating that the above considerations will not easily yield a non-lattice polygon with optimal dynamics.Isolating the properties necessary for our proof of Theorem3.1,we say that a pair of polygons(P,Q)is suitable if the following hold:•P is a lattice polygon.•P tiles Q by reﬂections.•The corresponding cover M Q→M P as in Proposition2.3has a unique branch point which is aperiodic.In her M.Sc.thesis at Ben Gurion University,theﬁrst-named author conducted an exten-sive search for a suitable pair of polygons.By Corollary2.2,such a pair will have yielded a non-lattice polygon with optimal dynamics.The search begins with a list of candidates for P,i.e.a list of currently known lattice polygons.At present,due to work of many authors, there is a fairly large list of known lattice polygons but there is no classiﬁcation of all lattice polygons.In[4],the full list of lattice polygons known as of this writing is given,and the following is proved:Theorem4.1(M.Cohen)Among the list of lattice surfaces given in[4],there is no P for which there is Q such that(P,Q)is a suitable pair.The proof of Theorem4.1contains a detailed case-by-case analysis for each of the differ-ent possible P.These cases involve some common arguments which we will illustrate in this section,by proving the special case in which P is any of the obtuse triangles investigated byWard[14]:Theorem4.2For n≥4,let P=P n be the(lattice)triangle with angles1n,12n,2n−32n.Then there is no polygon Q for which(P,Q)is a suitable pair.Our proof relies on some auxiliary statements which are of independent interest.In all of them,M Q→M P is the branched cover with unique branch point corresponding to a suitable pair(P,Q).These statements are also valid in the more general case in which P,Q are parking garages.Recall that an afﬁne automorphism of a translation surface is a homeomorphism which is linear in charts.We denote by Aff(M)the group of afﬁne automorphisms of M and by D:Aff(M)→GL2(R)the homomorphism mapping an afﬁne automorphism to its linear part.Note that we allow orientation-reversing afﬁne automorphisms,i.e.detϕmay be1 or−1.We now explain how G P acts on M P by translation equivalence.LetπP:N×G P→M P and S be as in the discussion preceding Proposition2.3,and let g∈G P.Since the left action of g on G is a permutation and preserves the gluing ruleπP,the map N×G P→N×G P sending(x,g )to(x,g−1g )induces a homeomorphismϕ:S→S and g◦h◦ϕis a translation in charts.Thus g∈G P gives a translation isomorphism of M P,and similarly g∈G P gives a translation isomorphism of M Q.Lemma4.3The branch point of the cover p:M Q→M P isﬁxed by G Q.Proof Since G Q⊂G P,any g∈G Q induces translation isomorphisms of both M P and M Q.We denote both by g.The definition of p given in theﬁrst paragraph of the proof of Proposition2.3shows that p◦g=g◦p;namely both maps are induced by sending (x ,g )∈N ×G Q toπP(x,gg g i),where x =h i(x).Since the cover p has a unique branch point,any g∈G Q mustﬁx it. Lemma4.4If an afﬁne automorphismϕof a translation surface has inﬁnitely manyﬁxed points then Dϕﬁxes a nonzero vector,in its linear action on R2.Proof Suppose by contradiction that the linear action of Dϕon the plane has zero as a uniqueﬁxed point,and let Fϕbe the set ofﬁxed points forϕ.For any x∈Fϕwhich is not a singularity,there is a chart from a neighborhood U x of x to R2with x→0,and a smaller neighborhood V x⊂U x,such thatϕ(V x)⊂U x and when expressed in this chart,ϕ|V x is given by the linear action of Dϕon the plane.In particular x is the onlyﬁxed point in V x. Similarly,if x∈Fϕis a singularity,then there is a neighborhood U x of x which maps to R2 via aﬁnite branched cover ramiﬁed at x→0,such that the action ofϕin V x⊂U x covers the linear action of Dϕ.Again we see that x is the onlyﬁxed point in V x.By compactness weﬁnd that Fϕisﬁnite,contrary to hypothesis. Lemma4.5Suppose M is a lattice surface andϕ∈Aff(M)has Dϕ=−Id.Then aﬁxed point forϕis periodic.Proof LetF1={σ∈Aff(M):Dσ=−Id}.Thenϕ∈F1and F1isﬁnite,since it is a coset for the group ker D which is known to be ﬁnite.Let A⊂M be the set of points which areﬁxed by someσ∈F1.By Lemma4.4this is aﬁnite set,which contains theﬁxed points forϕ.Thus in order to prove the Lemma,it sufﬁces to show that A is Aff(M)-invariant.Letψ∈Aff(M),and let x∈A,so that x=σ(x)with Dσ=−Id.Since-Id is central in GL2(R),D(σψ)=D(ψσ),so there is f∈ker D such thatψσ=fσψ.Thereforeψ(x)=ψσ(x)=fσψ(x),and fσ∈F1.This proves thatψ(x)∈A.Remark4.6This improves Theorem10of[8],where a similar conclusion is obtained under the additional assumptions that M is hyperelliptic and Aff(M)is generated by elliptic ele-ments.The following are immediate consequences:Corollary4.7Suppose(P,Q)is a suitable pair.Then•−Id/∈D(G Q).•None of the angles between two edges of Q are of the form p/q with gcd(p,q)=1and q even.Proof of Theorem4.2We will suppose that Q is such that(P,Q)are a suitable pair and reach a contradiction.If n is even,then Aff(M P)contains a rotation byπwhichﬁxes the points in M P coming from vertices of P.Thus by Lemma4.5all vertices of P give rise to periodic points,contradicting Proposition2.1(c).So n must be odd.Let x1,x2,x3be the vertices of P with corresponding angles1/n,1/2n,(2n−3)/2n. Then x3gives rise to a singularity,hence a periodic point.Also using Lemma4.5and the rotation byπ,one sees that x2also gives rise to a periodic point.So the unique branch point must correspond to the vertex x1.The images of the vertex x1in P give rise to two regular points in M P,marked c1,c2in Fig.2.Any element of G P acts on{c1,c2}by a permutation, so by Lemma4.3,G Q must be contained in the subgroup of index twoﬁxing both of the c i. Let e1be the edge of P opposite x1.Since the reﬂection in e1,or any edge which is an image of e1under G P,swaps the c i,we have:e1is not a boundary edge of Q.(2) We now claim that in Q,any vertex which corresponds to the vertex x3from P is alwaysdoubled,i.e.consists of an angle of(2n−3)/n.Indeed,for any polygon P0,the group G P0 is the dihedral group D N where N is the least common multiple of the denominators of theangles at vertices of P0.In particular it contains-Id when N is even.Writing(2n−3)/2n in reduced form we have an even denominator,and since,by Corollary4.7,−Id/∈G Q,in Q the angle at vertex x3must be multiplied by an even integer2k.Since2k(2n−3)/2n is bigger than2if k>1,and since the total angle at a vertex of a polygon is less than2π,we must have k=1,i.e.any vertex in Q corresponding to the vertex x3is always doubled.This establishes the claim.It is here that we have used the assumption that Q is a polygon and not a parking garage.Fig.2Ward’s surface,n=5Fig.3Two options to start the construction ofQThere are two possible conﬁgurations in which a vertex x3is doubled,as shown in Fig.3. The bold lines indicate lines which are external,i.e.boundary edges of Q.By(2),the con-ﬁguration on the right cannot occur.Let us denote the polygon on the left hand side of Fig.3by Q0.It cannot be equal to Q,since it is a lattice polygon.We now enlarge Q0by adding copies of P step by step,as described in Fig.4.Without loss of generality weﬁrst add triangle number1.By(2),the broken line indicates a side which must be internal in Q.Therefore,we add triangle number 2.We denote the resulting polygon by Q1.One can check by computing angles,using thefact that n is odd,and using Proposition2.3(4)that the cover M Q1→M P will branch overthe points a corresponding to vertex x2.Since the allowed branching is only over the points corresponding to x1,we must have Q1 Q,so we continue the construction.Without loss of generality we add triangle number3.Again,by(2),the broken line indicates a side which must be internal in Q.Therefore,we add triangle number4,obtaining Q2.Now,using Prop-osition2.3(4)again,in the cover M Q2→M P we have branching over two vertices u andv which are both of type x1and correspond to distinct points c1and c2in M P.This implies Q2 Q.Fig.4Steps of the construction of QSince both vertices u and v are delimited by2external sides,we cannot change the angle to prevent the branching over one of these points.This means that no matter how we continue to construct Q,the branching in the cover M Q→M P will occur over at least two points—a contradiction.Acknowledgments We are grateful to Yitwah Cheung and Patrick Hooper for helpful discussions,and to the referee for a careful reading and helpful remarks which improved the presentation.This research was supported by the Israel Science Foundation and the Binational Science Foundation.References1.Arnoux,P.,Schmidt,T.:Veech surfaces with non-periodic directions in the traceﬁeld.J.Mod.Dyn.3(4),611–629(2009)2.Bouw,I.,Möller,M.:Teichmüller curves,triangle groups,and Lyapunov exponents.Ann.Math.172,139–185(2010)3.Cheung,Y.,Hubert,P.,Masur,H.:Topological dichotomy and strict ergodicity for translation surfaces.Ergod.Theory Dyn.Syst.28,1729–1748(2008)4.Cohen,M.:Looking for a Billiard Table which is not a Lattice Polygon but satisﬁes the Veech dichotomy,M.Sc.thesis,Ben-Gurion University(2010)/pdf/1011.32175.DeMarco,L.:The conformal geometry of billiards.Bull.AMS48(1),33–52(2011)6.Eskin,A.,Marklof,J.,Morris,D.:Unipotentﬂows on the space of branched covers of Veech surfaces.Ergod.Theorm Dyn.Syst.26(1),129–162(2006)7.Fox,R.H.,Kershner,R.B.:Concerning the transitive properties of geodesics on a rational polyhe-dron.Duke Math.J.2(1),147–150(1936)8.Gutkin,E.,Hubert,P.,Schmidt,T.:Afﬁne diffeomorphisms of translation surfaces:Periodic points,Fuchsian groups,and arithmeticity.Ann.Sci.École Norm.Sup.(4)36,847–866(2003)9.Hubert,P.,Schmidt,T.:Inﬁnitely generated Veech groups.Duke Math.J.123(1),49–69(2004)10.Masur,H.,Tabachnikov,S.:Rational billiards andﬂat structures.In:Handbook of dynamical systems,vol.1A,pp.1015–1089.North-Holland,Amsterdam(2002)11.Smillie,J.,Weiss,B.:Veech dichotomy and the lattice property.Ergod.Theorm.Dyn.Syst.28,1959–1972(2008)Geom Dedicata12.Veech,W.A.:Teichmüller curves in moduli space,Eisenstein series and an application to triangularbilliards.Invent.Math.97,553–583(1989)13.V orobets,Y.:Planar structures and billiards in rational polygons:the Veech alternative.(Russian);trans-lation in Russian Math.Surveys51(5),779–817(1996)14.Ward,C.C.:Calculation of Fuchsian groups associated to billiards in a rational triangle.Ergod.TheoryDyn.Syst.18,1019–1042(1998)15.Zemlyakov,A.,Katok,A.:Topological transitivity of billiards in polygons,Math.Notes USSR Acad.Sci:18:2291–300(1975).(English translation in Math.Notes18:2760–764)16.Zorich,A.:Flat surfaces.In:Cartier,P.,Julia,B.,Moussa,P.,Vanhove,P.(eds.)Frontiers in numbertheory,physics and geometry,Springer,Berlin(2006)123。

土木工程外文翻译-原文

外文原文Response of a reinforced concrete infilled—frame structure to removal of twoadjacent columnsMehrdad Sasani_Northeastern University, 400 Snell Engineering Center，Boston，MA 02115, UnitedStatesReceived 27 June 2007；received in revised form 26 December 2007；accepted 24January 2008Available online 19 March 2008AbstractThe response of Hotel San Diego，a six—story reinforced concrete infilled-frame structure，is evaluated following the simultaneous removal of two adjacent exterior columns. Analytical models of the structure using the Finite Element Method as well as the Applied Element Method are used to calculate global and local deformations. The analytical results show good agreement with experimental data. The structure resisted progressive collapse with a measured maximum vertical displacement of only one quarter of an inch （6.4 mm）。

工程管理外文翻译(原文+译文)

Concrete Construction matterT. Pauly, M. J. N. PriestleyAbstractViewed in terms of accepted practices, concrete construction operations leave much to be desired with respect to the quality, serviceability, and safety of completed structures. The shortcomings of these operations became abundantly clear when a magnitude 7.6 earthquake struck northern Paki-stan on October 8, 2005, destroying thousands of buildings, damaging bridges, and killing an esti-mated 79,000 people. The unusually low quality of construction operations prevalent was a major cause of the immense devastation.Keywords: Concrete Placing Curing Construction TechnologyPlacing ConcreteIf concrete is placed in the surface, the sur-face should be filled with water sufficiently to prevent it from absorbing the concrete of its water. If fresh concrete is to be placed on or nearby to concrete that has solidified, the surface of the placed concrete should be cleaned absolutely, preferably with a high-pressure air or water jet or steel-wire brushes. The surface should be wet, but there should be no much water. A little quantity of cement grout should be brushed over the whole area, and then followed immediately with the application of a 1/2-in Layer of mortar. The fresh concrete should be placed on or against the mortar.In order to decrease the disintegration re-sulting from carriage after it is placed. The con-crete should be placed as nearly as probably in itsfinal point. It should be placed in layers to permit uniform compaction. The time interval between the placing of layers should be limited to assure perfect bond between the fresh and previously placed concrete.In placing concrete in deeper patters, a ves-sel should be used to limit the free fall to not over 3 or 4 ft, in order to prevent concrete disintegra-tion. The vessel is a pipe made of lightweight metal, having adjustable lengths and attached to the bottom of a hopper into which the concrete is deposited. As the patters are filled, sections of the pipe may be removed.Immediately after the concrete is placed, it should be compacted by hand pudding or a me-chanical vibrator to eliminate voids. The vibrator should be left in one position only long enough to reduce the concrete around it to a plastic mass; then the vibrator should be moved, or disintegra-tion of the aggregate will occur. In general, the vibrator should not be permitted to penetrate concrete in the prior lift.The mainly advantage of vibrating is that it permits the use of a drier concrete, which has a higher strength because of the reduced water content. Among the advantages of vibrating con-crete are the following:1.The decreased water permits a reduction in the cement and fine aggregate because less cement paste is needed.2.The lower water content decreases shrinkage and voids.3.The drier concrete decreases the cost of finishing the surface.4.Mechanical vibration may replace three to eight hand puddles.5.The lower water content increases the strength of the concrete.6.The drier mixture permits theremoval of some patters more quickly, which may reduce the cost of patters.Curing ConcreteIf concrete is to gain its maximum strength and other desirable properties, it should be cured with adequate moisture and at a favorable tem-perature. Failure to provide these conditions may result in an inferior concrete.The initial moisture in concrete is adequate to hydrate all the cement, provided it is not should replace the moisture that does evaporate. This may be accomplished by many methods, such as leaving the patters in place, keeping the surface wet, or covering the surface with a liquid curing compound, which comes being to a water-tight membrane that prevents the escape of the initial water. Curing compounds may be applied by brushes or pressure sprayers. A gallon will cover 200 to 300 sq ft.Concrete should be placed at a temperature not less than 40 or more than 80°F.A lower tem-perature will decrease the rate of setting, while ahigher temperature will decrease the ultimate strength.Placing Concrete in Cold WeatherWhen the concrete is placed during cold weather, it is usually necessary to preheat the water, the aggregate, or both in order that the ini-tial temperature will assure an initial set and gain in strength .Preheating the water is the most ef-fective method of providing the necessary tem-perature. For this purpose a water reservoir should be equipped with pipe coils through which steam can be passed, or steam may bedischarged directly into the water, several outlets being used to given better distribution of the heat.When the temperatures of the mixtures are known, some specific charts may be used to cal-culate the temperature of concrete. A straight line pass all three scales, passing through every two known temperatures, will assure the determina-tion of the third temperature. If the surface of sand isdry, the fact lines of the scales giving the temperature of concrete should be used. However, if the sand contains about 3 percent moisture, the dotted lines should be used.Specifications usually demand that freshly placed concrete shall be kept at a temperature of not less than 70°F for 3 days or 50°F for 5 days after it is placed. Some proper method must be provided to keep the demanded temperature when the cold weather is estimated.Reinforcing steels for concreteCompared with concrete, steel is a high strength material. The useful strength of ordinary reinforcing steels in tension as well as compres-sion, i.e., the yield strength, is about 15 times the compressive strength of common structural con-crete, and well over 100 times its tensile strength. On the other hand, steel is a high-cost material compared with concrete. It follow that the two materials are the best used in combination if theconcrete is made to resist the compressive stresses and the compressive force, longitudinal steel reinforcing bars are located close to the ten-sion face to resist the tension force., and usually additional steel bars are so disposed that they re-sist the inclined tension stresses that are caused by the shear force in the beams. However, rein-forcement is also used for resisting compressive forces primarily where it is desired to reduce the cross-sectional dimensions of compression members, as in the lower-floor columns of multi-story buildings. Even if no such necessity exits , a minimum amount of reinforce- ment is placed in all compression members to safeguard them against the effects of small accidental bending moments that might crack and even fail an unre-inforced member.For most effective reinforcing action, it is essential that steel and concrete deform together, i. e., that there be a sufficiently strong bond be-tween the two materials to ensure that no relative movements of the steel bars and the surrounding concrete occur. This bond is provided by the rela-tively large chemical adhesion which develops at the steel-concrete interface, by the natural roughness of the mill scale of hot-rolled rein-forcing bars , and by the closely spaced rib-shap-ed surface deformations with which reinforcing bars are furnished in order to provide a high de-gree of interlocking of the two materials.Steel is used in two different ways in con-crete structures: as reinforcing steel and as prestressing steel .reinforcing steel is placed in the forms prior to casting of the concrete. Stresses in the steel, as in the hardened concrete, are caused only by the loads on the structure, except for possible parasitic stresses from shrinkage or similar causes. In contrast, in priestesses concrete structures large tension forces are applied to the reinforcement prior to letting it act jointly with the concrete in resistingexternal.The most common type of reinforcing steel is in the form of round bars, sometimes called rebars, available in a large range of diameters,from 10 to 35 mm for ordinary applications and in two heavy bar sizes off 44 and 57 mm these bars are furnished with surface deformations for the purpose of increasing resistance to slip be-tween steel and concrete minimum requirements for these deformations have been developed in experimental research. Different bar producers use different patterns, all of which satisfy these requirements.Welding of rebars in making splices, or for convenience in fabricating reinforcing cages for placement in the forms, may result in metal-lurgical changes that reduce both strength and ductility, and special restrictions must be placed both strength and ductility, and special restric-tions must be placed both on the type of steel used and the welding procedures the provisions of ASTM A706 relatespecifically to welding.In reinforced concrete a long-time trend is evident toward the use of higher strength materi-als, both steel and concrete.Reinforcing bars with 40ksi yield stress , almost standard 20 years ago , have largely been replaced by bars with 60ksi yield stress , both because they are more economical and because their use tends to reduce congestion of steel in the forms .The ACI Code permits reinforcing steels up to Fy=80ksi. Such high strength steels usually yield gradually but have no yield plateau in this situation the ACI Code requires that at the speci-fied minimum yield strength the total strain shall not exceed 0.0035 this is necessary to make cur-rent design methods, which were developed for sharp-yielding steels with a yield plateau, appli-cable to such higher strength steels. there is no ASTM specification for deformed bars may be used , according to the ACI Code , providing they meet the requirements stated under special circumstances steel in this higher strength range has its place, e.g., in lower-story columns of high-rise buildings.In order to minimize corrosion of rein-forcement and consequent spelling of concrete under sever exposure conditions such as in bridge decks subjected to deicing chemicals , galvanized or epoxy-coated rebars may be specified.Repair of Concrete StructuresReinforced concrete is generally a very du-rable structural material and very little repair work is usually needed. However, its durability can be affected by a variety of causes, including those of design and construction faults, use of inferior materials and exposure to aggressive en-vironment. The need for a repair is primarily dic-tated by the severity of the deterioration as de-termined from the diagnosis. Good workmanship is essential if any thing more than just a cosmetic treatment to the creation is required.1. performance requirements of repair systemHaving established the causes of the defect by carefully diagnosing the distress, the next step should be to consider the requirements of the re-pair method that will offer an effective solution to the problem (see fig.).①DurabilityIt is important to select repair materials that provide adequate durability. Materials used for the repair job should be at least as durable as the substrate concrete to which it is applied.②Protection of steelThe mechanism of protection provided to the reinforcing depends on the type of repair ma-terials used. For example, cementations materials can protect the steel from further corrosion by their inhibitive effect of increasing the alkalinity of the concrete, whereas epoxy resin mortars can give protection against the ingress of oxygen,moisture and other harmful agents.③Bond with substrateThe bond with the substrate must produce an integral repair to prevent entry of moisture and atmospheric gases at the interface. With most re-pair materials, the bond is greatly enhanced with the use of a suitable bonding aid such as an un-filled epoxy resin systems and slurry of Portland cement, plus any latex additives for a Portland cement-based repair system. Precautions should also be takento remove all loose and friable ma-terials from the surfaces to be bonded.④Dimensional StabilityShrinkage of materials during curing should be kept to a minimum. Subsequent dimensional change should be very close in the substrate in order to prevent failure⑤Initial Resistance to Environmentally In-duced DamageSome initial exposure conditions may lead to premature damage lo repairs. For example, partially cured Portland cement repairs can dete-riorate from hot weather preventing full hydration of the cement. To prevent this from happening extra protection during curing time may be nec-essary.⑥Ease of ApplicationMaterials should be easily mixed and ap-plied so that they can be worked readily into small crevices and voids. Ideally, the material should not stick to tools, and should not shear while being trowel led nor slump after placement.⑦AppearanceThe degree to which the repair material should match the existing concrete will depend on the use of the structure and the client' s re-quirements. A surface coating may be required when appearance is important or when cover to reinforcement is small.2. Selection of Repair MethodsA suitable repair counteracts all the defi-ciencies which are relevant to the use of the structure.The selection of tile correct method and material for a particular, application requires careful consideration, whether to meet special requirements for placing strength, durability or other short-or long-term properties. These con-siderations include:1. Nature of the DistressIf alive crack is filled with a rigid material, then either the repair material will eventually fail or some new cracking will occur adjacent to the original crack. Repairs to live cracks must either use flexible materials to accommodate move-ments or else steps must be taken prior to the re-pair to eliminate the movement.2. Position of the CrackTechniques which rely on gravity to intro-duce the material into the crack are more suc-cessfully carried out on horizontal surfaces but are rarely effective on vertical ones.3. EnvironmentIf moisture, water or contaminants are found in the crack, then it is necessary to rectify the leaks Repair to slop leaks may be further com-plicated by the need to make the repairs while the structure is in service and the environment is damp.4. WorkmanshipThe skill the operatives available to carry put the repairs is another relevant factors. Some-times this can mean the difference between a permanent repair and premature failure of the re-pair material.5. CostThe cost of repair materials is usually small compared with the costs of providing access, preparation and actual labor.6. AppearanceThe repair surface may be unsightly, par-ticularly when it appears on a prominent part of the building. In this case, the repair system will include some form of treatment over the entire surface.Reference[1]Philip Jodidio, Contemporary European Architecture, Taschen, Koln, pp.148-153[2]Ann Breen & Dick Rigby, Waterfronts, McGraw-Hill, Inc. New York, 1994, pp.297-300[3]Ann Breen & Dick Rigby, The New Waterfront, Thames and Hudson, London, 1996, pp.118-120[4]Ann Breen & Dick Rigby, The New Waterfront, Thames and Hudson, London, 1996, pp.52-55[5]Robert Holden, International Landscape Design, Laurence King Publishing, London, 1996, pp.10-27[6] A new concept in refrigerant control for heat pumps ,J.R.Harnish,IIR Conference Pa-per,Cleveland,Ohio.May,1996[7]Carrier Corporation-Catalog 523 848,1997[8]Waste Heat Management Handbook, Na-tional Bureau of Standardc Handbook 121, Pub-lica-tion PB 264959, February,1997Ten design principles for air to air heat pumps,Allen Trask,ASHRAE Journal,July,1997重庆科技学院学生毕业设计（论文）外文译文学院建建筑工程学院专业班级工管103学生姓名李学号201044241附件1：外文资料翻译译文混凝土施工事项T.Pauly, M.J.N.Priestley摘要：根据一般承认的惯例看,巴基斯坦的混凝土结构建筑物在结构上的质量，效用和安全需要上都留下了很多值得关注的问题。

外文翻译原文.

e c o l o g i c a l e n g i n e e r i n g 28(2006124–130a v a i l ab l e a t w w w.sc i e n c ed i re c t.c omj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e c o l e n gPlant-bioﬁlm oxidation ditch for in situ treatm ent of polluted watersQi-Tang Wu a ,∗,Ting Gao a ,Shucai Zeng a ,Hong Chua ba College of Natural Resources and Environment,South China Agricultural University,Guangzhou 510642,ChinabDepartment of Civil and Structural Engineering,Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong SAR,Chinaa r t i c l ei n f o Article history:Received 17December 2005Received in revised form 16May 2006Accepted 18May 2006Keywords:Plant-bioﬁlm oxidation ditch (PBFODIn situWastewater treatmenta b s t r a c tEutrophication of surface water bodies is a problem of increasing environmental and ecolog-ical concern worldwide and is particularly serious in China.In the present study,oxidation ditches were connected to a lake receiving municipal sewage sludges.T wo 24m 2(width 2m,length 12mparallel plastic oxidation ditches material were installed on a lake near the inlet of the municipal sewage.Zizania caduciﬂora and Canna generalis were grown in the ditches with plastic ﬂoating supporters for the removal of N and P from the sewage.The experiment was conducted ﬁrstly with municipal sewage in autumn–winter seasons for about 150daysunder the following conditions:2m 3/h inﬂuent ﬂow,0.75kW jet-ﬂow aerator(air/water of 5,18h HRT (hydrological retention timeand a return ratio of 10.Then it was run with the polluted lake water in summer–autumn for about 160days with an aerator of 1.25kW and an inﬂuent of 6m 3/h (air/water 3.3,HRT 6h.The performance was quite stable during the experimental period for the municipal sewage treatment.The average removal rates of COD (chemical oxygen demand,SS (suspended solids,TP (total phosphorus,NH 4+-N and inorganic-N were 70.6,75.8,72.6,52.1and50.3%,respectively.For the polluted lake water treatment,the average concentrations of COD,NH 4+-N and TP were 42.7,13.1and 1.09mg/L,respectively,in the inﬂuent and were 25.1,6.4and 0.38mg/L,respectively,in the efﬂuent.The capacity of the plants to remove N and P by direct uptake was limited,but the indi-rect mechanisms also occurred.The proposed process,transforming the natural lake into a wastewater treatment plant,could evidently reduce the costs of the sewage collection,the land space requirement and the construction compared with conventional sewage treat-ment plants,and is especially suited to conditions in south China and south-east Asia.©2006Elsevier B.V .All rights reserved.1.IntroductionMany water bodies are subject to eutrophication due to eco-nomic constraints in reducing point sources of nutrients and/or to a high proportion of diffuse sources,and the prob-lem is particularly common in China because the proportion of treated municipal sewage is still low due to the relatively high capital investmentrequired.Accordingly,43.5%of 130investi-gated major lakes in China were found to be highly eutrophied∗Corresponding author .Tel.:+862085280296;fax:+862085288326.E-mail address:qitangwu@ (Q.-T.Wu.and 45%were of intermediate status (Li et al.,2000.These pol-luted lakes were mainly located in economically developed regions and especially around cities where large amounts of municipal sewage are discharged without appropriate treat-ment.Increasingly,natural or constructed wetlands,including buffer zones(Correll,2005,are being used for removal of pol-lutants from wastewater or for treatment of stormwater runoff from agricultural land and other non-point sources (Mitsch ete c o l o g i c a l e n g i n e e r i n g28(2006124–130125Table1–COD and BOD5of the study lake sampled at three points for5days inMay2003COD(mg/LBOD5(mg/LBOD5/COD13May89.5135.700.4083.3334.500.4189.5136.600.4114May55.5624.800.4589.5135.200.3949.3820.900.4227May105.1141.300.3981.0832.300.40111.1141.000.3728May60.0026.830.4563.3327.700.4463.3327.000.4329May90.0035.700.4093.3337.000.40117.9949.400.42al.,2000;Coveney et al.,2002;Belmont et al.,2004.However, this method requires a large land area in addition to the lake in question.For in situ treatment of hypereutrophic water bodies where the transparency of the water does not allow regrowth of submerged macrophytes,phosphorus precipitation in eutrophic lakes by iron application(Deppe and Benndorf, 2002or by additions of lime(Walpersdorf et al.,2004has been reported.Aeration of river water has been employed to remediate polluted rivers since the1970s(Wang et al.,1999. Increasing oxygen transfer inﬂow by stones placed in rivers was studied by Cokgor and Kucukali(2004.Growingﬂoating aquatic macrophytes(Sooknah and Wilkie,2004or terrestrial green plants usingﬂoating supports(Li and Wu,1997,physical ecological engineering(PEEN(Pu et al.,1998,and biotic addi-tives have also been applied(Chen,2003.However,these sim-ple designs do not constitute a real water treatment system and the efﬁciencies of these treatments are unsatisfactory.Activated sludge systems have been proved efﬁcient treat-ing municipal sewage since the1960s(Ray,1995.However, this type of system has not been used for in situ remediation of polluted lakes or rivers.In the present study,the oxidation ditch technique was adopted on a lake receiving municipal sewage sludge.Floating green plants and the bioﬁlms com-prisingﬂoating materials and plant roots were also added to enhance N and P removal.A pilot scale experiment was set up to test the feasibility and performance of the plant-enhanced oxidation ditch for in situ treatment ofboth the municipal sewage and the polluted lake water.2.Experimental2.1.Site descriptionThe study lake was situated at South China Agricultural Uni-versity,Guangzhou,China.The area of the lake was about 10000m2and the depth0.5–3m.This lake received the munic-ipal sewage from the residential area around the university.Fig.1–Surface arrangement of the plant-bioﬁlm oxidation ditch and the waterﬂows.(1Wall of nylon tissue;(2nets of5mm;(3nets of0.25mm;(4oxidation ditch;(5jet-ﬂow aerator;(6water pump;(7ﬂoating green plants;(8sewage entry.2.2.Establishment of the plant-bioﬁlm oxidationditchesT wo24m2(width2m,length12mparallel oxidation ditches made of plastic materials were installed along the lake bank near the sewage inlet.The inner ditch was made of cement and the outer ditch was isolated with nylon tissues andﬁx-ing PVC(polyvinyl chloridetubes.Fig.1showsthe surface arrangement and the waterﬂow path.The coarse suspended solids in the inﬂuent wereﬁltered by two pl astic nets,one with a pore size of5mm and the other with a pore size of0.25mm,whereas the suspended solids in the efﬂuent wereﬁltered by a plastic net with a pore size of 0.25mm.Zizania caduciﬂora and Canna generalis were grown in the ditch with theplast icﬂoating supporters which held the plants in position.Theﬂoating supporters were made of closed126e c o l o g i c a l e n g i n e e r i n g28(2006124–130PVC tubes and nylon nets and each was3.6m2.Zizania caduci-ﬂora was grown on twoﬂoating supporters an d Canna gener-alis on another two supporters.The plants were planted in four columns andﬁve lines.The twoﬂoating supporters with Canna generalis were near the inﬂuent and the two with Zizania caduciﬂora were near the efﬂuent.The entire disposal system is shown in Photo1.2.3.Conduct of the experimentsAn experiment was conductedﬁrstly on municipal sewage in autumn–winter seasons of2003–2004for about150days. The aeration of the oxidation ditch was achieved using a jet-ﬂow aerator of0.75kW(Aqua Co.,Italy;air generation10m3/h, water jet rate22–28m3/h.The water sampling started on18 September2003and endedon12February2004.The inﬂuent was2m3/h created by a water pump of0.37kW.With the jet-ﬂow aerator of0.75kW the theoretical air/water ratio was5, HRT was18h and the return ratio was10–13.The system was then run with the polluted lake water in summer and autumn2004for about160days with an aerator of1.25kW and with an inﬂuent of6m3/h(air/water3.3,HRT 6h.The inﬂuent was not created by water pump but by the driving fo rce of the jet-ﬂow aerator.The water sampling for the second run started on15May2004and endedon15October 2004.2.4.Sampling and analysisThe inﬂuent and efﬂuent were sampled every3–5days at 08:00–09:00a.m.andat17:00–18:00p.m.,each with three sam-pling re plicates for theﬁrst run.For the second run,the inﬂu-ent and efﬂuent were sampled1day a week.The water sam-pler took0–30cm surface water.The samples were analyzed for COD Cr,BOD5,SS,TP,NO3−-N,NH4+-N and pH according to standard methods(APHA,1995.The plant s were transplanted ontoﬂoating supporters two weeks before water sampling and theﬁrst harvest was carried out60days later and at the termination of theﬁrst run for the municipal sewage.The plant biomass and N and P con-tents were measured according to the methods proposed by the Soil and Agro-Chemical Analysis Committee of China(Lu, 2000.The total uptakes of N and P were calculated and com-pared with the total removal of these elements calculated by the cumulative removal each day following measurement of a water sample.Total N removal=(average N in inﬂuent−average N in efﬂuent×48×D iwhere48was the treated water volume per day in m3/day;D i was the number of days following the water sampling and before the next sampling.3.Results and discussionTable2shows the removal of COD Cr and SS by plant-bioﬁlm oxidation ditch for the treatment of the municipal sewage in autumn–winter seasons of2003–2004.The removal of COD Cr varied from60to79%with an average of70%for the inﬂuent COD Cr ranging from100to200mg/L,a nd resulted in efﬂuent COD Cr valuesfrom30to55mg/L(Table2,Fig.2.The average removal percentage was about75%for SS and variedfrom68to82%(Table2.The efﬂuent SS was about 30mg/L which is the efﬂuent limit value of the second grade for the sewage treatment plants in China(GB18918,2002 (Fig.3,for the inﬂuents varying from60to240mg/L.The average NH4+-N removal from inﬂuent was52%,which was lower in winter than in autumn(Table3.This may be due to lower bacterial activity in winter,but theinﬂuent NH4+-NTable2–Removal of COD and SS by the plant-bioﬁlm oxidation ditch for the in situ treatment of municipal sewage each month in autumn–winter seasons of2003–2004Period Sampled days Water temperature(◦CInﬂuent(mg/LEfﬂuent(mg/LRemoval(%COD Cr18–30September528.0118.54(3.01a34.34(7.8367.74 3–28October826.1123.91(4.0333.51(4.2672.661–7November326.0153.94(2.7337.60(3.8175.4918–28November423.1170.22(4.2835.45(5.3778.711–15December419.3180.36(8.2039.24(7.0677.6511–31January314.5128.46(3.6652.04(5.2359.504–12February216.8178.35(4.1662.86(5.8362.47Average150.54(4.3042.15(5.6370.60SS18–30September528.0160.4041.6074.18 3–28October826.1144.3826.2581.171–7November326.0116.0033.3370.7918–28November423.1111.7521.5080.981–15December419.390.5028.5068.4211–31January314.5104.0017.3382.384–12February216.8120.5033.0072.57Average121.0828.7975.78e c o l o g i c a l e n g i n e e r i n g28(2006124–130127Fig.2–COD in the inﬂuent and efﬂuent of the plant-bioﬁlm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.was also higher in winter(Fig.4probably because of lower water consumption in the cold season.The total inorganic-N removal was similar to that for NH4+-N(Table3.NO3−-N concentrations were rather similar in the inﬂuent and the efﬂuent.The total P removal varied from63to78%and was higher and more regular than N removal(Table3.The P concentra-tion in treated efﬂuent was about1mg/L(Fig.5and conformed to the Chinese municipal sewage treatment standard which is set to3mg/L for second grade regions and1.5forﬁrst grade regions(GB18918,2002.Fig.6shows typical changes in the water quality param-eters for the sampling points from inlet to outlet.Thisindi-Fig.3–Suspended solids concentration in the inﬂuent and efﬂuent of the p lant-bioﬁlm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.cates that COD and SS decreased gradually,but NH4+-N and TP dropped substantially following the mixing with the return water by the aerator and then decreased slowly,while NO3−-N and pH of the water remained virtually unchanged.The water DO increased dramatically following the aeration,decreased slowly thereafter and remained rather high even in the efﬂu-ent(about5.5mg/L.For the second run treating the polluted lake water on-site,the average inﬂuent COD Cr was42.7mg/L and the efﬂuent 25.1mg/L for about160days during summer–autumn seasons (Fig.7.The removal of NH4+-N was about50%from about13.1 to6.4mg/L.Total-P in the efﬂuents was rather stable,bei ngTable3–The removal of N and P by the plant-bioﬁlm oxidation ditch for the in situ treatment of municipal sewage for each month in autumn–winter seasons of2003–2004Period Sampled days Water temperature(◦CInﬂuent(mg/LEfﬂuent(mg/LRemoval(%NH4+-N18–30September528.020.60(0.30a7.16(0.2264.72 3–28October826.126.55(0.2310.15(0.2061.671–7November326.030.00(0.4113.67(0.2254.5118–28November423.135.15(0.7915.95(0.2653.991–15December419.335.89(0.3515.93(0.2755.1511–31January314.530.57(0.6918.59(0.2236.634–12February216.835.23(0.0521.61(0.0637.72Average30.57(0.4014.72(0.2152.06NH4+-N+NO3−-N18–30September528.023.06(0.159.24(0.1159.94 3–28October826.128.31(0.1212.01(0.1457.571–7November326.031.42(0.2114.58(0.1153.5918–28November423.136.32(0.4016.81(0.1353.721–15December419.337.41(0.1917.54(0.1453.1111–31January314.531.96(0.3720.07(0.1337.204–12February216.837.11(0.0323.35(0.0337.08Average32.23(0.2116.23(0.1150.32TP18–30September528.0 3.56(0.070.81(0.0475.56 3–28October826.1 4.01(0.140.87(0.0478.241–7November326.0 4.37(0.13 1.20(0.0472.5618–28November423.1 4.89(0.16 1.13(0.0776.661–15December319.5 4.86(0.80 1.38(0.2371.07 11–31January314.5 3.75(0.45 1.35(0.0363.32 4–12February216.8 4.75(0.10 1.51(0.0566.20 Average 4.31(0.16 1.16(0.0471.89128e c o l o g i c a l e n g i n e e r i n g 28(2006 124–130Fig.4–NH 4+-N concentration in the inﬂuent and efﬂuent of the plant-bioﬁlm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.Fig.5–Total-P concentration in the inﬂuent and efﬂuent of the plant-bioﬁlm oxidation ditch for the in situ treatment of municipal sewage in autumn–winter seasons of2003–2004.Fig.6–T ypical changes in the pollutants in theplant-bioﬁlm oxidation ditch during the in situ treatment ofFig.7–The inﬂuent and efﬂuent concentrations of COD (up,NH 4+-N (medianand total-P (bottomin theplant-bioﬁlm oxidation ditch treating polluted lake water.about 0.38mg/L from an average of 1.09mg/L in the inﬂuents.The removal of COD Cr ,NH 4+-N and Total-P was then quite sat-isfactory both for the municipal sewage and the polluted lake water.The removal of N and P was somewhat higher than con-ventional oxidation ditches,perhaps due to the existence of the plant-bioﬁlm in the studiedsystem.However,the direct uptake rates of N and P by green plants were almost negligi-ble compared to the total removal of these elements by the whole system (Table4.However,the plants may have cre-ated localized anaerobic conditions by their root exudates and dead biomass and enhance the denitriﬁcation of N by micro-organisms as occurs in constructed wetlands (Hone,2000.Besides the green plants,the proposed system also con-tains bioﬁlm coated to the plastic materials.The high velocity of return-ﬂuent was different to the conventional oxidation ditch.Kugaprasatham et al.(1982showed that the increase of the ﬂuent velocity could increase the density of the bioﬁlm if the nutrient conditions were suitable for bacteria growth.Simultaneous nitriﬁcation/denitriﬁcation (SND(Van Mun ch etal.,1996may also occur in the system.Concerning the P removal of the system,biological phos-phate removal processes may occur but were not signiﬁcant because there was no sludge removal and very little sludge precipitation after the run for treatment of municipal sewage.This may partly due to the existence of some ferric chains which were added to precipitate and ﬁx the nylon tissue to the lake bottom,with formation of precipitates of ferric phos-e c o l o g i c a l e n g i n e e r i n g 2 8 ( 2 0 0 6 124–130 129 Table 4 – Proportions of N and P uptake by plants and total removal in the plant-bioﬁlm oxidation ditch treating municipal sewage Date Days ZCa Harvested fresh biomass (g CG ZC 5 September–4 November 5 November–6 January Total or average a Plant uptake (g N CG 5.30 13.03 System removal (kg N CG P Percent of plant uptake N (% P (% P ZC 0.88 0.24 2.79 60 63 123 2200 625 9725 2750 4150 4.85 1.20 24.38 0.72 0.95 37.63 65.45 103.1 7.13 12.78 19.91 0.03 0.02 0.02 0.02 0.01 0.01 ZC: Zizania caduciﬂo ra; CG: Canna generalis. tained for at least 1 year. The actual mechanisms still remain to be identiﬁed. The oxidation ditch has been used for many years worldwide as an economical and efﬁcient wastewater treatment technology that can remove COD, nitrogen and a fraction of the phosphorusefﬁciently. Anaerobic tanks (Liu et al., 2002 and phased isolation ditch systems with intra-channel clariﬁer (Hong et al., 2003 were added to the system to increase the TP removal efﬁciency. The proposed process takes an artiﬁcial process in combination with natural puriﬁcation, transforming the natural lake into the wastewater treatment plant, and could evidently reduce the costs of sewage collection, the landspace requirement and the construction costs compared with the conventional sewage treatment plants. This process could be especially suitable to subtropical regions and to many water bodies in south China and southeast Asia where sewage treatment facilities are not well established. China. The authors are grateful to Dr. P. Christie, Department of Agricultural and Environmental Science, Queen’s University Belfast, UK, and Dr. Y. Ouyang, Department of Water Resources, St. Johns River Water Management District, Palatka, FL, USA, for their valuable suggestions and language corrections. references 4. Conclusions The present study adapted the oxidation ditch on the lake surface for in situ treatment of municipal sewage or polluted lake water in combination with plant bioﬁlms for performing N and P removal, and running experiments at pilot scale for about 1.5 years resulted in the following observations: (1 The system was quite satisfactory and stable for treatment of municipal sewage and polluted lake water in removing COD, NH4 + -N and P. (2 The direct uptake of N and P by plants was negligible in comparison with the totalremoval by the system, but indirect mechanisms via plant root exudates and bioﬁlms merit further studies. (3 The proposed process could dramatically reduce the costs of sewage collection, the land-space requirement and the construction costs compared with conventional sewage treatment plants; might be suitable for treatment of both municipal sewage and polluted lake water; and could lead to the promotion of wastewater treatment in many developing countries. Acknowledgements This study was funded by Department of Science and Technology of Guangdong Province (Grant no. 2004B33301007, American Public Health Association (APHA, 1995. Standards Methods for the Examination of Water and Wastewater, 19th ed. American Public Health Association, Washington, DC. Belmont, M.A., Cantellano, E., Thompson, S., Williamson, M.,S’anchez, A., Metcalfe, C.D., 2004. Treatment of domestic wastewater in a pilot-scale natural treatment system in central Mexico. Ecol. Eng. 23, 299–311. Chen, Y.C., 2003. Bioremediation Engineering of Polluted Environment. Chemical Industry Press, Beijing, p. 304 (in Chinese. Cokgor, S., Kucukali, S., 2004. Oxygen transfer in ﬂow around and over stones placed in a laboratory ﬂume. Ecol. Eng. 23, 205–219. Correll, D.L., 2005. Principles of planning and establishment of buffer zones. Ecol. Eng. 24, 433–439. Coveney, M.F., Stites, D.L., Lowe, E.F., Battoe, L.E., Conrow, R., 2002. Nutrient removal from eutrophic lake water by wetland ﬁltration. Ecol. Eng. 19, 141–159. Deppe, T., Benndorf, J., 2002. Phosphorus reduction in a shallow hypereutrophic reservoir by in-lake dosage of ferrous iron. Water Res. 36, 4525–4534. Hone, A.J., 2000. Phytoremediation by constructed wetlands. In: Terry, N., Banuelos, G. (Eds., Phytoremediation of Contaminated Soil and Water. Lewis Publishers, pp. 13–40. Hong, K.H., Chang, D., Hur, J.M., Han, S.B., 2003. Novel phased isolation ditch system for enhanced nutrient removal and its optimal operating strategy. J. Environ. Sci. Health Part A 38, 2179–2189. Kugaprasatham, S., Nagaoka, H., Ohgaki, S., 1982. Effect of turbulence on nitrifying bioﬁlms at non-limiting substrate conditions. Water Res. 26, 1629–1638. Li, F.X., Xin, Y., Chen, W., 2000. Assessment of eutrophication level of lakes. Chongqing Environ. Sci. 22, 10–11 (in Chinese. Li, F.B., Wu, Q.T., 1997.Domestic wastewater treatment with means of soilless cultivated plants. Chin. J. Appl. Ecol. 8, 88–92 (in Chinese. Liu, J.X., Wang, B.Z., van Groenestijn, J.W., Doddema, H.J., 2002. Addition of anaerobic tanks to an oxidation ditch system to enhance removal of phosphorus from wastewater. J. Environ. Sci. 14, 245–249.130 e c o l o g i c a l e n g i n e e r i n g 2 8 ( 2 0 0 6 124–130 Lu, R.K., 2000. Soil and Agricultural Chemistry Analysis. China Agriculture Press, Beijing (in Chinese. Mitsch, W.J., Horne, A.J., Nairn, R.W., 2000. Nitrogen and phosphorus retention in wetlands—ecological approaches to solving excess nutrient problems. Ecol. Eng. 14, 1–7. Pu, P., Hu, W., Yan, J., Wang, G., Hu, C., 1998. A physico-ecological engineering experiment for water treatment in a hypertrophic lake in China. Ecol. Eng. 10, 179–190. Ray, B.T., 1995. Environmental Engineering. PWS Publishing Company, New York, pp. 299–341. Sooknah, R.D., Wilkie, A.C., 2004. Nutrient removal by ﬂoating aquatic macrophytes cultured in anaerobically digested ﬂushed dairy manure wastewater. Ecol. Eng. 22, 27–42. Van Munch, E.P., Land, P., Keller, J., 1996. Simultaneous nitriﬁcation and denitriﬁcation in bench-scale sequencing batch reactors. Water Sci. Technol. 20,277–284. Wang, C.X., Lin, H., Shi, K.H., 1999. Restoration of polluted river by pure oxygen aeration. Shanghai Environ. Sci. 18, 411–413 (in Chinese. Walpersdorf, E., Neumann, T., Stuben, D., 2004. Efﬁciency of natural calcite precipitation compared to lake marl application used for water quality improvement in an eutrophic lake. Appl. Geochem. 19, 1687–1698.。

外文翻译资料原文

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' ,SPECTRALCANCELLATION In figure 1, wave A is a square wave moving between the
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values +I and -1. Wave B is a sinusoidal wave with the same fundamental frequency. Multiplying the waves generates wave C, a function that is always positive. Fourier analysis will show that the square wave, A, has spectral power at the frequency of the sine wave, B, because the average value of this product function, C, is non-zero. Figure 2 shows a similar set of waves, except that wave A is a square wave inverted every third cycle. Wave B is the same sinusoid as before, and wave C is the product of the two waves. Wave C is the argument of the Fourier integral. Note that the average value of wave C is exactly zero. Modified square wave A has no spectral power at the frequency of sine wave B. Repeated inversion has suppressedthis frequency.

外文翻译--外文原文

外文翻译--外文原文MCU DescriptionSCM is also known as micro-controller (Microcontroller Unit), commonly used letters of the acronym MCU MCU that it was first used in industrial control. Only a single chip by the CPU chip developed from a dedicated processor. The first design is by a large number of peripherals and CPU on a chip in the computer system, smaller, more easily integrated into a complex and demanding on the volume control device which. INTEL's Z80 is the first designed in accordance with this idea processor, then on the development of microcontroller and dedicated processors have parted ways.Are 8-bit microcontroller early or 4 bits. One of the most successful is the INTEL 8031, for a simple, reliable and good performance was a lot of praise. Then developed in 8031 out of MCS51 MCU Systems. SCM systems based on this system until now is still widely used. With the increased requirements of industrial control field, began a 16-bit microcontroller, because the cost is not satisfactory but have not been very widely used. After 90 years with the great development of consumer electronics, microcontroller technology has been a huge increase. With INTEL i960 series, especially the later series of widely used ARM, 32-bit microcontroller quickly replace high-end 16-bit MCU status and enter the mainstream market. The traditional 8-bit microcontroller performance have been the rapid increase capacity increase compared to 80 the number of times. Currently, high-end 32-bit microcontroller clocked over 300MHz, the performance catching the mid-90's dedicated processor, while the average model prices fall to one U.S. dollars, the most high-end [1] model only 10 dollars. Modern SCM systems are no longer only in the development and use of bare metal environment, a large number of proprietary embedded operating system is widely used in the full range of SCM. The handheld computers and cell phones as the core processing of high-end microcontroller can even use a dedicated Windows and Linux operating systems.SCM is more suitable than the specific processor used in embedded systems, so it was up to the application. In fact the number of SCM is the world's largest computer. Modern human life used in almost every piece of electronic and mechanical products will be integrated single chip. Phone, telephone, calculator, home appliances, electronic toys, handheld computers and computer accessories such as a mouse with a 1-2 in both the Department of SCM. Personal computer will have a large number ofSCM in the work. General car with more than 40 SCM, complex industrial control systems may even have hundreds of SCM in the same time work! SCM is not only far exceeds the number of PC and other computing the sum, or even more than the number of human beingsSingle chip, also known as single-chip microcontroller, it is not complete a certain logic chips, but to a computer system integrated into a chip. Equivalent to a micro-computer, and computer than just the lack of a microcontroller I / O devices. General talk: a chip becomes a computer. Its small size, light weight, cheap, for the study, application and development of facilities provided. At the same time, learning to use the MCU is to understand the principle and structure of the computer the best choice.SCM and the computer functions internally with similar modules, such as CPU, memory, parallel bus, the same effect as well, and hard disk memory devices, and different is its performance of these components were relatively weak many of our home computer, but the price is low , usually not more than 10 yuan you can do with it ...... some control for a class is not very complicated electrical work is enough of. We are using automatic drum washing machine, smoke hood, VCD and so on appliances which could see its shadow! ...... It is primarily as a control section of the core componentsIt is an online real-time control computer, control-line is that the scene is needed is a stronger anti-jamming ability, low cost, and this is, and off-line computer (such as home PC), the main difference.Single chipMCU is through running, and can be modified. Through different procedures to achieve different functions, in particular special unique features, this is another device much effort needs to be done, some great efforts are very difficult to do. A not very complex functions if the 50's with the United States developed 74 series, or the 60's CD4000 series of these pure hardware buttoned, then the circuit must be a large PCB board! But if the United States if the 70's with a series of successful SCM market, the result will be a drastic change! Just because you are prepared by microcomputer programs can achieve high intelligence, high efficiency and high reliability!As the microcontroller on the cost-sensitive, so now the dominant software or the lowest level assembly language, which is the lowest level in addition to more than binary machine code language, and as so low why is the use? Many high-levellanguage has reached the level of visual programming Why is not it? The reason is simply that there is no home computer as a single chip CPU, not as hard as a mass storage device. A visualization of small high-level language program which even if only one button, will reach tens of K of size! For the home PC's hard drive in terms of nothing, but in terms of the MCU is not acceptable. SCM in the utilization of hardware resources to be very high for the job so although the original is still in the compilation of a lot of use. The same token, if the giant computer operating system and applications run up to get home PC, home PC, also can not afford to.Can be said that the twentieth century across the three "power" era, that is, the age of electricity, the electronic age and has entered into the computer age. However, this computer, usually refers to the personal computer, referred to as PC. It consists of the host, keyboard, monitor and other components. Another type of computer, most people do not know how. This computer is to give all kinds of intelligent machines single chip (also known as micro-controller). As the name suggests, this computer system took only a minimal integrated circuit, can be a simple operation and control. Because it is small, usually hidden in the charged mechanical "stomach" in. It is in the device, like the human brain plays a role, it goes wrong, the whole plant was paralyzed. Now, this microcontroller has a very broad field of use, such as smart meters, real-time industrial control, communications equipment, navigation systems, and household appliances. Once all kinds of products were using SCM, can serve to upgrade the effectiveness of products, often in the product name preceded by the adjective - "intelligent," such as intelligent washing machines. Now some technical personnel of factories or other amateur electronics developers to engage in out of certain products, not the circuit is too complicated, that function is too simple and can easily be copied. The reason may be stuck in the product did not use a microcontroller or other programmable logic device.SCM historySCM was born in the late 20th century, 70, experienced SCM, MCU, SoC three stages.First model1.SCM the single chip microcomputer (Single Chip Microcomputer) stage, mainly seeking the best of the best single form of embedded systems architecture. "Innovation model" success, laying the SCM and general computer completely different path of development. In the open road of independent development ofembedded systems, Intel Corporation contributed.2.MCU the micro-controller (Micro Controller Unit) stage, the main direction of technology development: expanding to meet the embedded applications, the target system requirements for the various peripheral circuits and interface circuits, highlight the object of intelligent control. It involves the areas associated with the object system, therefore, the development of MCU's responsibility inevitably falls on electrical, electronics manufacturers. From this point of view, Intel faded MCU development has its objective factors. In the development of MCU, the most famous manufacturers as the number of Philips Corporation.Philips company in embedded applications, its great advantage, the MCS-51 single-chip micro-computer from the rapid development of the micro-controller. Therefore, when we look back at the path of development of embedded systems, do not forget Intel and Philips in History.Embedded SystemsEmbedded system microcontroller is an independent development path, the MCU important factor in the development stage, is seeking applications to maximize the solution on the chip; Therefore, the development of dedicated single chip SoC trend of the natural form. As the microelectronics, IC design, EDA tools development, application system based on MCU SoC design have greater development. Therefore, the understanding of the microcontroller chip microcomputer can be, extended to the single-chip micro-controller applications.MCU applicationsSCM now permeate all areas of our lives, which is almost difficult to find traces of the field without SCM. Missile navigation equipment, aircraft, all types of instrument control, computer network communications and data transmission, industrial automation, real-time process control and data processing, extensive use of various smart IC card, civilian luxury car security system, video recorder, camera, fully automatic washing machine control, and program-controlled toys, electronic pet, etc., which are inseparable from the microcontroller. Not to mention the area of robot control, intelligent instruments, medical equipment was. Therefore, the MCU learning, development and application of the large number of computer applications and intelligent control of the scientists, engineers.SCM is widely used in instruments and meters, household appliances, medical equipment, aerospace, specialized equipment, intelligent management and processcontrol fields, roughly divided into the following several areas:1. In the application of Intelligent InstrumentsSCM has a small size, low power consumption, controlling function, expansion flexibility, the advantages of miniaturization and ease of use, widely used instrument, combining different types of sensors can be realized Zhuru voltage, power, frequency, humidity, temperature, flow, speed, thickness, angle, length, hardness, elemental, physical pressure measurement. SCM makes use of digital instruments, intelligence, miniaturization, and functionality than electronic or digital circuits more powerful. Such as precision measuring equipment (power meter, oscilloscope, various analytical instrument).2. In the industrial control applicationWith the MCU can constitute a variety of control systems, data acquisition system. Such as factory assembly line of intelligent control3. In Household AppliancesCan be said that the appliances are basically using SCM, praise from the electric rice, washing machines, refrigerators, air conditioners, color TV, and other audio video equipment, to the electronic weighing equipment, varied, and omnipresent.4. In the field of computer networks and communications applicationsMCU general with modern communication interface, can be easy with the computer data communication, networking and communications in computer applications between devices had excellent material conditions, are basically all communication equipment to achieve a controlled by MCU from mobile phone, telephone, mini-program-controlled switchboards, building automated communications call system, train radio communication, to the daily work can be seen everywhere in the mobile phones, trunked mobile radio, walkie-talkies, etc.5. Microcomputer in the field of medical device applicationsSCM in the use of medical devices is also quite extensive, such as medical respirator, the various analyzers, monitors, ultrasound diagnostic equipment and hospital beds, etc. call system.6. In a variety of major appliances in the modular applicationsDesigned to achieve some special single specific function to be modular in a variety of circuit applications, without requiring the use of personnel to understand its internal structure. If music integrated single chip, seemingly simple function, miniature electronic chip in the net (the principle is different from the tape machine),you need a computer similar to the principle of the complex. Such as: music signal to digital form stored in memory (like ROM), read by the microcontroller, analog music into electrical signals (similar to the sound card).In large circuits, modular applications that greatly reduce the volume, simplifies the circuit and reduce the damage, error rate, but also easy to replace.7. Microcontroller in the application field of automotive equipmentSCM in automotive electronics is widely used, such as a vehicle engine controller, CAN bus-based Intelligent Electronic Control Engine, GPS navigation system, abs anti-lock braking system, brake system, etc..In addition, the MCU in business, finance, research, education, national defense, aerospace and other fields has a very wide range of applications.Application of six important part of learningMCU learning an important part of the six applications1, Bus:We know that a circuit is always made by the devices connected by wires, in analog circuits, the connection does not become a problem because the device is a serial relationship between the general, the device is not much connection between the , but the computer is not the same circuit, it is a microprocessor core, the device must be connected with the microprocessor, the device must be coordination between, so they need to connect on a lot, as if still analog circuit like the microprocessor and devices in the connection between the individual, the number of lines will be a little more surprising, therefore the introduction of the microprocessor bus Zhong Each device Gongtong access connections, all devices 8 Shuju line all received eight public online, that is the equivalent of all devices together in parallel, but only this does not work, if there are two devices send data at the same time, a 0, a 1, then, whether the receiver received what is it? This situation is not allowed, so to be controlled by controlling the line, time-sharing the device to work at any time only one device to send data (which can have multiple devices to receive both). Device's data connection is known as the data bus, the device is called line of control all the control bus. Internal or external memory in the microcontroller and other devices have memory cells, the memory cell to be assigned addresses, you can use, distribution, of course, to address given in the form of electrical signals, and as more memory cells, so, for the address allocation The line is also more of these lines is called the address bus.Second, data, address, command:The reason why these three together because of the nature of these three are the same - the number, or are a string of '0 'and '1' form the sequence. In other words, addresses, instructions are also data. Instruction: from single chip designer provides a number of commonly used instructions with mnemonic we have a strict correspondence between the developer can not be changed by the MCU. Address: the search for MCU internal, external storage units, input and output port based on the address of the internal unit value provided by the chip designer is good, can not be changed, the external unit can be single chip developers to decide, but there are a number of address units is a must (see procedures for the implementation of the process).Third, P0 port, P2 and P3 of the second function I use:Beginners often on the P0 port, P2 and P3 port I use the second function puzzled that the second function and have a switch between the original function of the process, or have a directive, in fact, the port The second feature is automatic, do not need instructions to convert. Such as P3.6, P3.7 respectively WR, RD signal, when the microchip processing machines external RAM or external I / O port, they are used as a second function, not as a general-purpose I / O port used, so long as a A microprocessor implementation of the MOVX instruction, there will be a corresponding signal sent from the P3.6 or P3.7, no prior use of commands. In fact 'not as a general-purpose I / O port use' is also not a 'no' but (user) 'not' as a general-purpose I / O port to use. You can arrange the order of a SETB P3.7's instructions, and when the MCU execution to the instruction, the also make P3.7 into a high, but users will not do so because this is usually will cause the system to collapse.Fourth, the program's implementation:Reduction in power after the 8051 microcontroller within the program counter (PC) in the value of 0000 ', the process is always from the 0000' units started, that is: the system must exist in ROM 0000 'this unit , and in 0000 'unit must be stored in a single instruction.5, the stack:Stack is a region, is used to store data, there is no special about the region itself is a part of internal RAM, special access to its data storage and the way that the so-called 'advanced post out backward first out ', and the stack has a special data transmission instructions that' PUSH 'and' POP ', has a special expertise in its servicesunit, that is, the stack pointer SP, whenever a PUSH instruction execution, SP on (in the Based on the original value) automatically add 1, whenever the implementation of a POP instruction, SP will (on the basis of the original value) automatically by 1. As the SP values can be changed with the instructions, so long as the beginning of the process to change the value of the SP, you can set the stack memory unit required, such as the program begins, with an MOV SP, # 5FH instructions When set on the stack starting from the memory unit 60H unit. There is always the beginning of the general procedure with such a directive to set the stack pointer, because boot, SP initial value of 07H, 08H This unit from the beginning to stack next, and 08H to 1FH 8031 is the second in the region, three or four working register area, often used, this will lead to confusion of data. Different authors when writing programs, initialize the stack is not exactly the same directive, which is the author's habit. When set up the stack zone, does not mean that the region become a special memory, it can still use the same memory region as normal, but generally the programmer does not regard it as an ordinary memory used.From the world of radio in the world to a single chipModern computer technology, industrial revolution, the world economy from the capital into the economy to knowledge economy. Field in the electronic world, from the 20th century into the era of radio to computer technology in the 21st century as the center of the intelligent modern era of electronic systems. The basic core of modern electronic systems are embedded computer systems (referred to as embedded systems), while the microcontroller is the most typical and most extensive and most popular embedded systems.First, radio has created generations of excellence in the worldFifties and sixties in the 20th century, the most representative of the advanced electronic technology is wireless technology, including radio broadcasting, radio, wireless communications (telegraph), Amateur Radio, radio positioning, navigation and other telemetry, remote control, remote technology. Early that these electronic technology led many young people into the wonderful digital world, radio show was a wonderful life, the prospects for science and technology. Electronics began to form a new discipline. Radio electronics, wireless communications began e-world journey. Radio technology not only as a representative of advanced science and technology at that time, but also from popular to professional fields of science, attracting the young people and enable them to find a lot of fun. Ore from the bedside to thesuperheterodyne radio radio; report issued from the radio amateur radio stations; from the telephone, electric bell to the radio control model. Became popular youth radio technology, science and technology education is the most popular and most extensive content. So far, many of the older generation of engineers, experts, Professor of the year are radio enthusiasts. Fun radio technology, radio technology, comprehensive training, from basic principles of electronics, electronic components to the radio-based remote control, telemetry, remote electronic systems, has trained several generations of technological excellence.Second, from the popularity of the radio era to era of electronic technologyThe early radio technology to promote the development of electronic technology, most notably electronic vacuum tube technology to semiconductor electronic technology. Semiconductor technology to realize the active device miniaturization and low cost, so more popular with radio technology and innovation, and to greatly broaden the number of non-radio-control areas.The development of semiconductor technology lead to the production of integrated circuit, forming the modern electronic technology leap from discrete electronics into the era of era of integrated circuits. Electronic design engineers no longer use the discrete electronic components designed circuit modules, and direct selection of integrated circuit components constitute a single system. They freed the design of the circuit unit dedicated to system design, greatly liberating the productive forces of science and technology, promote the wider spread of electronic systems.Semiconductor integrated circuits in the basic digital logic circuits first breakthrough.A large number of digital logic circuits, such as gates, counters, timers, shift registers, and analog switches, comparators, etc., for the electronic digital control provides excellent conditions for the traditional mechanical control to electronic control. Power electronic devices and sensor technology to make the original to the radio as the center of electronic technology turned to mechanical engineering in the field of digital control systems, testing in the field of information collection, movement of electrical mechanical servo drive control object.Semiconductor and integrated circuit technology will bring us a universal age of electronic technology, wireless technology as the field of electronic technology a part of.70 years into the 20th century, large scale integrated circuit appeared to promotethe conventional electronic circuit unit-specific electronic systems development. Many electronic systems unit into a dedicated integrated devices such as radios, electronic clocks, calculators, electronic engineers in these areas from the circuit, the system designed to debug into the device selection, peripheral device adapter work. Electronic technology, and electronic products enriched, electronic engineers to reduce the difficulty, but at the same time, radio technology, electronic technology has weakened the charm. The development of semiconductor integrated circuits classical electronic systems are maturing, remain in the large scale integrated circuit other than the shrinking of electronic technology, electronic technology is not the old days of radio fun times and comprehensive engineering training.Third, from the classic era of electronic technology to modern electronic technology of the times80 years into the 20th century, the century of economic change is the most important revolution in the computer. The computer revolution in the most important sign is the birth of the computer embedded applications. Modern computer numerical requirements should be born. A long period of time, is to develop the massive computer numerical duty. But the computer shows the logic operation, processing, control, attracting experts in the field of electronic control, they want development to meet the control object requirements of embedded applications, computer systems. If you meet the massive data-processing computer system known as general-purpose computer system, then the system can be the embedded object (such as ships, aircraft, motorcycles, etc.) in a computer system called the embedded computer. Clearly, both the direction of technology development are different. The former requires massive data storage, handling, processing and analysis of high-speed data transmission; while the latter requires reliable operation in the target environment, the external physical parameters on high-speed acquisition, analysis and processing logic and the rapid control of external objects. It will add an early general-purpose computer data acquisition unit, the output driver circuit reluctance to form a heat treatment furnace temperature control system. This general-purpose computer system is not possible for most of the electronic system used, and to make general-purpose computer system meets the requirements of embedded applications, will inevitably affect the development of high-speed numeric processing. In order to solve the contradiction between the development of computer technology, in the 20th century 70s, semiconductor experts another way, in full accordance with the electronic systemembedded computer application requirements, a micro-computer's basic system on a chip, the formation of the early SCM (Single Chip Microcomputer). After the advent of single chip in the computer industry began to appear in the general-purpose computer systems and embedded systems the two branches. Since then, both the embedded system, or general-purpose computer systems have been developed rapidly.Although the early general-purpose computer converted the embedded computer systems, and real embedded system began in the emergence of SCM. Because the microcontroller is designed specifically for embedded applications, the MCU can only achieve embedded applications. MCU embedded applications that best meet environmental requirements, for example, chip-level physical space, large-scale integrated circuits low-cost, good peripheral interface bus and outstanding control of instruction.A computer system microcontroller core, embedded electronic systems, intelligent electronic systems for the foundation. Therefore, the current single chip electronic system in widespread use of electronic systems to enable rapid transition to the classical modern intelligent electronic systems.4, single chip to create the modern era of electronic systemsA microcontroller and embedded systemsEmbedded computer systems from embedded applications, embedded systems for early general-purpose computer adapted to the object system embedded in a variety of electronic systems, such as the ship's autopilot, engine monitoring systems. Embedded system is primarily a computer system, followed by it being embedded into the object system, objects in the object system to achieve required data collection, processing, status display, the output control functions, as embedded in the object system, embedded system computer does not have an independent form and function of the computer. SCM is entirely in accordance with the requirements of embedded system design, so SCM is the most typical embedded systems. SCM is the early application of technical requirements in accordance with the design of embedded computer chip integration, hence the name single chip. Subsequently, the MCU embedded applications to meet the growing demands of its control functions and peripheral interface functions, in particular, highlight the control function, so has international name the single chip microcontroller (MCU, Microcontroller Unit).2 MCU modern electronic systems consisting of electronic systems will become mainstream。

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下页附：外文翻译与原文参考格式2英文翻译 (黑体、四号、顶格)外文原文出处：(译文前列出外文原文出处、作者、国籍，译文后附上外文原文)《ASHRAE Handbook —Refrigeration 》.CHAPTER3 .SYSTEM Practices for ammonia 3.1 System Selection 3.2 Equipment3.10 Reciprocating Compressors第3章氨制冷系统的实施3.1 系统选择在选择一个氨制冷系统设计时，须要考虑一些设计决策要素，包括是否采用（1）单级压缩（2）带经济器的压缩（3）多级压缩（4）直接蒸发（5）满液式（6）液体再循环（7）载冷剂。

单级压缩系统基本的单级压缩系统由蒸发器、压缩机、冷凝器、储液器（假如用的话）和制冷剂控制装置（膨胀阀、浮球阀等）。

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英文原文(黑体、四号、顶格)英文翻译2（黑体，四号，顶格）外文原文出处：（黑体，四号，顶格）P. Fanning. Nonlinear Models of Reinforced and Post-tensioned Concrete Beams. Lecturer, Department of Civil Engineering, University College Dublin. Received 16 Jul 2001.非线形模型钢筋和后张法预应力混凝土梁摘要:商业有限元软件一般包括混凝土在荷载做用下非线性反应的专用数值模型。

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外文文献翻译原文Analysis of Con tin uous Prestressed Concrete BeamsChris BurgoyneMarch 26, 20051、IntroductionThis conference is devoted to the development of structural analysis rather than the strength of materials, but the effective use of prestressed concrete relies on an appropriate combination of structural analysis techniques with knowledge of the material behaviour. Design of prestressed concrete structures is usually left to specialists; the unwary will either make mistakes or spend inordinate time trying to extract a solution from the various equations.There are a number of fundamental differences between the behaviour of prestressed concrete and that of other materials. Structures are not unstressed when unloaded; the design space of feasible solutions is totally bounded；in hyperstatic structures, various states of self-stress can be induced by altering the cable profile, and all of these factors get influenced by creep and thermal effects. How were these problems recognised and how have they been tackled?Ever since the development of reinforced concrete by Hennebique at the end of the 19th century (Cusack 1984), it was recognised that steel and concrete could be more effectively combined if the steel was pretensioned, putting the concrete into compression. Cracking could be reduced, if not prevented altogether, which would increase stiffness and improve durability. Early attempts all failed because the initial prestress soon vanished, leaving the structure to be- have as though it was reinforced; good descriptions of these attempts are given by Leonhardt (1964) and Abeles (1964).It was Freyssineti’s observations of the sagging of the shallow arches on three bridges that he had just completed in 1927 over the River Allier near Vichy which led directly to prestressed concrete (Freyssinet 1956). Only the bridge at Boutiron survived WWII (Fig 1). Hitherto, it had been assumed that concrete had a Young’s modulus which remained fixed, but he recognised that the de- ferred strains due to creep explained why the prestress had been lost in the early trials. Freyssinet (Fig. 2) also correctly reasoned that high tensile steel had to be used, so that some prestress would remain after the creep had occurred, and alsothat high quality concrete should be used, since this minimised the total amount of creep. The history of Freyssineti’s early prestressed concrete work is written elsewhereFigure1:Boutiron Bridge,Vic h yFigure 2: Eugen FreyssinetAt about the same time work was underway on creep at the BRE laboratory in England ((Glanville 1930) and (1933)). It is debatable which man should be given credit for the discovery of creep but Freyssinet clearly gets the credit for successfully using the knowledge to prestress concrete.There are still problems associated with understanding how prestressed concrete works, partly because there is more than one way of thinking about it. These different philosophies are to some extent contradictory, and certainly confusing to the young engineer. It is also reflected, to a certain extent, in the various codes of practice.Permissible stress design philosophy sees prestressed concrete as a way of avoiding cracking by eliminating tensile stresses; the objective is for sufficient compression to remain after creep losses. Untensionedreinforcement, which attracts prestress due to creep, is anathema. This philosophy derives directly from Freyssinet’s logic and is primarily a working stress concept.Ultimate strength philosophy sees prestressing as a way of utilising high tensile steel as reinforcement. High strength steels have high elastic strain capacity, which could not be utilised when used as reinforcement; if the steel is pretensioned, much of that strain capacity is taken out before bonding the steel to the concrete. Structures designed this way are normally designed to be in compression everywhere under permanent loads, but allowed to crack under high live load. The idea derives directly from the work of Dischinger (1936) and his work on the bridge at Aue in 1939 (Schonberg and Fichter 1939), as well as that of Finsterwalder (1939). It is primarily an ultimate load concept. The idea of partial prestressing derives from these ideas.The Load-Balancing philosophy, introduced by T.Y. Lin, uses prestressing to counter the effect of the permanent loads (Lin 1963). The sag of the cables causes an upward force on the beam, which counteracts the load on the beam. Clearly, only one load can be balanced, but if this is taken as the total dead weight, then under that load the beam will perceive only the net axial prestress and will have no tendency to creep up or down.These three philosophies all have their champions, and heated debates take place between them as to which is the most fundamental.2、Section designFrom the outset it was recognised that prestressed concrete has to be checked at both the working load and the ultimate load. For steel structures, and those made from reinforced concrete, there is a fairly direct relationship between the load capacity under an allowable stress design, and that at the ultimate load under an ultimate strength design. Older codes were based on permissible stresses at the working load; new codes use moment capacities at the ultimate load. Different load factors are used in the two codes, but a structure which passes one code is likely to be acceptable under the other.For prestressed concrete, those ideas do not hold, since the structure is highly stressed, even when unloaded. A small increase of load can cause some stress limits to be breached, while a large increase in load might be needed to cross other limits. The designer has considerable freedom to vary both the working load and ultimate load capacities independently; both need to be checked.A designer normally has to check the tensile and compressive stresses, in both the top and bottom fibre of the section, for every load case. The critical sections are normally, but not always, the mid-span and the sections over piers but other sections may become critical ，when the cable profile has to be determined.The stresses at any position are made up of three components, one of which normally has a different sign from the other two; consistency of sign convention is essential.If P is the prestressing force and e its eccentricity, A and Z are the area of the cross-section and its elastic section modulus, while M is the applied moment, then where ft and fc are the permissible stresses in tension and compression.c e t f ZM Z P A P f ≤-+≤Thus, for any combination of P and M , the designer already has four in- equalities to deal with.The prestressing force differs over time, due to creep losses, and a designer isusually faced with at least three combinations of prestressing force and moment;• the applied moment at the time the prestress is first applied, before creep losses occur,• the maximum applied moment after creep losses, and• the minimum applied moment after creep losses.Figure 4: Gustave MagnelOther combinations may be needed in more complex cases. There are at least twelve inequalities that have to be satisfied at any cross-section, but since an I-section can be defined by six variables, and two are needed to define the prestress, the problem is over-specified and it is not immediately obvious which conditions are superfluous. In the hands of inexperienced engineers, the design process can be very long-winded. However, it is possible to separate out the design of the cross-section from the design of the prestress. By considering pairs of stress limits on the same fibre, but for different load cases, the effects of the prestress can be eliminated, leaving expressions of the form:rangestress e Perm issibl Range Mom entZ These inequalities, which can be evaluated exhaustively with little difficulty, allow the minimum size of the cross-section to be determined.Once a suitable cross-section has been found, the prestress can be designed using a construction due to Magnel (Fig.4). The stress limits can all be rearranged into the form:()M fZ PA Z e ++-≤1 By plotting these on a diagram of eccentricity versus the reciprocal of the prestressing force, a series of bound lines will be formed. Provided the inequalities (2) are satisfied, these bound lines will always leave a zone showing all feasible combinations of P and e. The most economical design, using the minimum prestress, usually lies on the right hand side of the diagram, where the design is limited by the permissible tensile stresses.Plotting the eccentricity on the vertical axis allows direct comparison with the crosssection, as shown in Fig. 5. Inequalities (3) make no reference to the physical dimensions of the structure, but these practical cover limits can be shown as wellA good designer knows how changes to the design and the loadings alter the Magnel diagram. Changing both the maximum andminimum bending moments, but keeping the range the same, raises and lowers the feasible region. If the moments become more sagging the feasible region gets lower in the beam.In general, as spans increase, the dead load moments increase in proportion to the live load. A stage will be reached where the economic point (A on Fig.5) moves outside the physical limits of the beam; Guyon (1951a) denoted the limiting condition as the critical span. Shorter spans will be governed by tensile stresses in the two extreme fibres, while longer spans will be governed by the limiting eccentricity and tensile stresses in the bottom fibre. However, it does not take a large increase in moment ，at which point compressive stresses will govern in the bottom fibre under maximum moment.Only when much longer spans are required, and the feasible region moves as far down as possible, does the structure become governed by compressive stresses in both fibres.3、Continuous beamsThe design of statically determinate beams is relatively straightforward; the engineer can work on the basis of the design of individual cross-sections, as outlined above. A number of complications arise when the structure is indeterminate which means that the designer has to consider, not only a critical section,but also the behaviour of the beam as a whole. These are due to the interaction of a number of factors, such as Creep, Temperature effects and Construction Sequence effects. It is the development of these ideas whichforms the core of this paper. The problems of continuity were addressed at a conference in London (Andrew and Witt 1951). The basic principles, and nomenclature, were already in use, but to modern eyes concentration on hand analysis techniques was unusual, and one of the principle concerns seems to have been the difficulty of estimating losses of prestressing force.3.1 Secondary MomentsA prestressing cable in a beam causes the structure to deflect. Unlike the statically determinate beam, where this motion is unrestrained, the movement causes a redistribution of the support reactions which in turn induces additional moments. These are often termed Secondary Moments, but they are not always small, or Parasitic Moments, but they are not always bad.Freyssinet’s bridge across the Marne at Luzancy, started in 1941 but not completed until 1946, is often thought of as a simply supported beam, but it was actually built as a two-hinged arch (Harris 1986), with support reactions adjusted by means of flat jacks and wedges which were later grouted-in (Fig.6). The same principles were applied in the later and larger beams built over the same river.Magnel built the first indeterminate beam bridge at Sclayn, in Belgium (Fig.7) in 1946. The cables are virtually straight, but he adjusted the deck profile so that the cables were close to the soffit near mid-span. Even with straight cables the sagging secondary momentsare large; about 50% of the hogging moment at the central support caused by dead and live load.The secondary moments cannot be found until the profile is known but the cablecannot be designed until the secondary moments are known. Guyon (1951b) introduced the concept of the concordant profile, which is a profile that causes no secondary moments; es and ep thus coincide. Any line of thrust is itself a concordant profile.The designer is then faced with a slightly simpler problem; a cable profile has to be chosen which not only satisfies the eccentricity limits (3) but is also concordant. That in itself is not a trivial operation, but is helped by the fact that the bending moment diagram that results from any load applied to a beam will itself be a concordant profile for a cable of constant force. Such loads are termed notional loads to distinguish them from the real loads on the structure. Superposition can be used to progressively build up a set of notional loads whose bending moment diagram gives the desired concordant profile.3.2 Temperature effectsTemperature variations apply to all structures but the effect on prestressed concrete beams can be more pronounced than in other structures. The temperature profile through the depth of a beam (Emerson 1973) can be split into three components for the purposes of calculation (Hambly 1991). The first causes a longitudinal expansion, which is normally released by the articulation of the structure; the second causes curvature which leads to deflection in all beams and reactant moments in continuous beams, while the third causes a set of self-equilibrating set of stresses across the cross-section.The reactant moments can be calculated and allowed-for, but it is the self- equilibrating stresses that cause the main problems for prestressed concrete beams. These beams normally have high thermal mass which means that daily temperature variations do not penetrate to the core of the structure. The result is a very non-uniform temperature distribution across the depth which in turn leads to significant self-equilibrating stresses. If the core of the structure is warm, while the surface is cool, such as at night, then quite large tensile stresses can be developed on the top and bottom surfaces. However, they only penetrate a very short distance into the concrete and the potential crack width is very small. It can be very expensive to overcome the tensile stress by changing the section or the prestress。

毕业论文外文翻译范例

外文原文(一)Savigny and his Anglo-American Disciple s*M. H. HoeflichFriedrich Carl von Savigny, nobleman, law reformer, champion of the revived German professoriate, and founder of the Historical School of jurisprudence, not only helped to revolutionize the study of law and legal institutions in Germany and in other civil law countries, but also exercised a profound influence on many of the most creative jurists and legal scholars in England and the United States. Nevertheless, tracing the influence of an individual is always a difficult task. It is especially difficult as regards Savigny and the approach to law and legal sources propounded by the Historical School. This difficulty arises, in part, because Savigny was not alone in adopting this approach. Hugo, for instance, espoused quite similar ideas in Germany; George Long echoed many of these concepts in England during the 1850s, and, of course, Sir Henry Sumner Maine also espoused many of these same concepts central to historical jurisprudence in England in the 1860s and 1870s. Thus, when one looks at the doctrinal writings of British and American jurists and legal scholars in the period before 1875, it is often impossible to say with any certainty that a particular idea which sounds very much the sort of thing that might, indeed, have been derived from Savigny's works, was, in fact, so derived. It is possible, nevertheless, to trace much of the influence of Savigny and his legal writings in the United States and in Great Britain during this period with some certainty because so great was his fame and so great was the respect accorded to his published work that explicit references to him and to his work abound in the doctrinal writing of this period, as well as in actual law cases in the courts. Thus, Max Gutzwiller, in his classic study Der einfluss Savignys auf die Entwicklung des International privatrechts, was able to show how Savigny's ideas on conflict of laws influenced such English and American scholars as Story, Phillimore, Burge, and Dicey. Similarly, Andreas Schwarz, in his "Einflusse Deutscher Zivilistik im Auslande," briefly sketched Savigny's influence upon John Austin, Frederick Pollock, and James Bryce. In this article I wish to examine Savigny's influence over a broader spectrum and to draw a picture of his general fame and reputation both in Britain and in the United States as the leading Romanist, legal historian, and German legal academic of his day. The picture of this Anglo-American respect accorded to Savigny and the historical school of jurisprudence which emerges from these sources is fascinating. It sheds light not only upon Savigny’s trans-channel, trans-Atlantic fame, but also upon the extraordinarily*M.H.Hoeflich, Savigny and his Anglo-American Disciples, American Journal of Comparative Law, vol.37, No.1, 1989.cosmopolitan outlook of many of the leading American and English jurists of the time. Of course, when one sets out to trace the influence of a particular individual and his work, it is necessary to demonstrate, if possible, precisely how knowledge of the man and his work was transmitted. In the case of Savigny and his work on Roman law and ideas of historical jurisprudence, there were three principal modes of transmission. First, there was the direct influence he exercised through his contacts with American lawyers and scholars. Second, there was the influence he exercised through his books. Third, there was the influence he exerted indirectly through intermediate scholars and their works. Let us examine each mode separately.I.INFLUENCE OF THE TRANSLATED WORKSWhile American and British interest in German legal scholarship was high in the antebellum period, the number of American and English jurists who could read German fluently was relatively low. Even those who borrowed from the Germans, for instance, Joseph Story, most often had to depend upon translations. It is thus quite important that Savigny’s works were amongst the most frequently translated into English, both in the United States and in Great Britain. His most influential early work, the Vom Beruf unserer Zeitfur Rechtsgeschichte und Gestzgebung, was translated into English by Abraham Hayward and published in London in 1831. Two years earlier the first volume of his History of Roman Law in the Middle Ages was translated by Cathcart and published in Edinburgh. In 1830, as well, a French translation was published at Paris. Sir Erskine Perry's translation of Savigny's Treatise on Possession was published in London in 1848. This was followed by Archibald Brown's epitome of the treatise on possession in 1872 and Rattigan's translation of the second volume of the System as Jural Relations or the Law of Persons in 1884. Guthrie published a translation of the seventh volume of the System as Private International Law at Edinburgh in 1869. Indeed, two English translations were even published in the far flung corners of the British Raj. A translation of the first volume of the System was published by William Holloway at Madras in 1867 and the volume on possession was translated by Kelleher and published at Calcutta in 1888. Thus, the determined English-speaking scholar had ample access to Savigny's works throughout the nineteenth century.Equally important for the dissemination of Savigny's ideas were those books and articles published in English that explained and analyzed his works. A number of these must have played an important role in this process. One of the earliest of these is John Reddie's Historical Notices of the Roman law and of the Progress of its Study in Germany, published at Edinburgh in 1826. Reddie was a noted Scots jurist and held the Gottingen J.U.D. The book, significantly, is dedicated to Gustav Hugo. It is of that genre known as an external history of Roman law-not so much a history of substantive Roman legal doctrine but rather a historyof Roman legal institutions and of the study of Roman law from antiquity through the nineteenth century. It is very much a polemic for the study of Roman law and for the Historical School. It imparts to the reader the excitement of Savigny and his followers about the study of law historically and it is clear that no reader of the work could possibly be left unmoved. It is, in short, the first work of public relations in English on behalf of Savigny and his ideas.Having mentioned Reddie's promotion of Savigny and the Historical School, it is important to understand the level of excitement with which things Roman and especially Roman law were greeted during this period. Many of the finest American jurists were attracted-to use Peter Stein's term-to Roman and Civil law, but attracted in a way that, at times, seems to have been more enthusiastic than intellectual. Similarly, Roman and Civil law excited much interest in Great Britain, as illustrated by the distinctly Roman influence to be found in the work of John Austin. The attraction of Roman and Civil law can be illustrated and best understood, perhaps, in the context of the publicity and excitement in the English-speaking world surrounding the discovery of the only complete manuscript of the classical Roman jurist Gaius' Institutes in Italy in 1816 by the ancient historian and German consul at Rome, B.G. Niebuhr. Niebuhr, the greatest ancient historian of his time, turned to Savigny for help with the Gaius manuscript (indeed, it was Savigny who recognized the manuscript for what it was) and, almost immediately, the books and journals-not just law journals by any means-were filled with accounts of the discovery, its importance to legal historical studies, and, of course, what it said. For instance, the second volume of the American Jurist contains a long article on the civil law by the scholarly Boston lawyer and classicist, John Pickering. The first quarter of the article is a gushing account of the discovery and first publication of the Gaius manuscript and a paean to Niebuhr and Savigny for their role in this. Similarly, in an article published in the London Law Magazine in 1829 on the civil law, the author contemptuously refers to a certain professor who continued to tell his students that the text of Gaius' Institutes was lost for all time. What could better show his ignorance of all things legal and literary than to be unaware of Niebuhr's great discovery?Another example of this reaction to the discovery of the Gaius palimpsest is to be found in David Irving's Introduction to the Study of the Civil Law. This volume is also more a history of Roman legal scholarship and sources than a study of substantive Roman law. Its pages are filled with references to Savigny's Geschichte and its approach clearly reflects the influence of the Historical School. Indeed, Irving speaks of Savigny's work as "one of the most remarkable productions of the age." He must have been truly impressed with German scholarship and must also have been able to convince the Faculty of Advocates, forwhom he was librarian, of the worth of German scholarship, for in 1820 the Faculty sent him to Gottingen so that he might study their law libraries. Irving devotes several pages of his elementary textbook on Roman law to the praise of the "remarkable" discovery of the Gaius palimpsest. He traces the discovery of the text by Niebuhr and Savigny in language that would have befitted an adventure tale. He elaborates on the various labors required to produce a new edition of the text and was particularly impressed by the use of a then new chemical process to make the under text of the palimpsest visible. He speaks of the reception of the new text as being greeted with "ardor and exultation" strong words for those who spend their lives amidst the "musty tomes" of the Roman law.This excitement over the Verona Gaius is really rather strange. Much of the substance of the Gaius text was already known to legal historians and civil lawyers from its incorporation into Justinian's Institutes and so, from a substantive legal perspective, the find was not crucial. The Gaius did provide new information on Roman procedural rules and it did also provide additional information for those scholars attempting to reconstruct pre-Justinianic Roman law. Nevertheless, these contributions alone seem hardly able to justify the excitement the discovery caused. Instead, I think that the Verona Gaius discovery simply hit a chord in the literary and legal community much the same as did the discovery of the Rosetta Stone or of Schliemann’s Troy. Here was a monument of a great civilization brought newly to light and able to be read for the first time in millenia. And just as the Rosetta Stone helped to establish the modern discipline of Egyptology and Schliemann's discoveries assured the development of classical archaeology as a modern academic discipline, the discovery of the Verona Gaius added to the attraction Roman law held for scholars and for lawyers, even amongst those who were not Romanists by profession. Ancillary to this, the discovery and publication of the Gaius manuscript also added to the fame of the two principals involved in the discovery, Niebuhr and Savigny. What this meant in the English-speaking world is that even those who could not or did not wish to read Savigny's technical works knew of him as one of the discoverers of the Gaius text. This fame itself may well have helped in spreading Savigny's legal and philosophical ideas, for, I would suggest, the Gaius "connection" may well have disposed people to read other of Savigny's writings, unconnected to the Gaius, because they were already familiar with his name.Another example of an English-speaking promoter of Savigny is Luther Stearns Cushing, a noted Boston lawyer who lectured on Roman law at the Harvard Law School in 1848-49 and again in 1851- 1852.Cushing published his lectures at Boston in 1854 under the title An Introduction to the Study of Roman Law. He devoted a full chapter to a description of the historical school and to the controversy betweenSavigny and Thibaut over codification. While Cushing attempted to portray fairly the arguments of both sides, he left no doubt as to his preference for Savigny's approach:The labors of the historical school have established an entirely new and distinct era in the study of the Roman jurisprudence; and though these writers cannot be said to have thrown their predecessors into the shade, it seems to be generally admitted, that almost every branch of the Roman law has received some important modification at their hands, and that a knowledge of their writings, to some extent, at least, is essentially necessary to its acquisition.译文(一)萨维尼和他的英美信徒们*M·H·豪弗里奇弗雷德里奇·卡尔·冯·萨维尼出身贵族，是一位出色的法律改革家，也是一位倡导重建德国教授协会的拥护者，还是历史法学派的创建人之一。

王德龙外文翻译原文

DC Switching Power Supply Protection Technology1、IntroductionDC switching regulator used in the price of more expensive high-power switching devices,the control circuit is also more complex,In addition,the load switching regulators are generally used a large number of highly integrated electronic systems installed devices. Transistors and integrated device tolerance electricity,less heat shocks.Switching Regulators therefore should take into account the protection of voltage regulators and load their own safety.Many different types of circuit protection,polarity protection,introduced here,the program protection,over-current protection,over-voltage protection,under-voltage protection and over-temperature protection ually chosen to be some combination of protection,constitutes a complete protection system.2、polarity protectionDC switching regulator input are generally not regulated DC power supply.Operating errors or accidents as a result of the situation will take its wrong polarity,switching power supply will be damaged.Polarity protection purposes,is to make the switching regulator only when the correct polarity is not connected to DC power supply regulator to work at. Connecting a single device can achieve power polarity protection.Since the diode D to flow through switching regulator input total current,this circuit applied in a low-power switching regulator more suitable.Power in the larger occasion,while the polarity protection circuit as a procedure to protect a link,save the power required for polarity protection diodes,power consumption will be reduced.In order to easy to operate,make it easier to identify the correct polarity or not,collect the next light.3、procedures to protectSwitching power supply circuit is rather complicated,basically can be divided into low-power and high-power part of the control part of the switch.Switch is a high-power transistors,for the protection of the transistor switch is turned on or off power safety,we must first modulator,amplifier and other low-power control circuit.To this end,the boot to ensure the correct procedures.Switching Regulators generally take the input of a small inductor,the input filter capacitor.Moment in the boot,filter capacitor will flow a lot of surge current,the surge current can be several times more than the normal input current. Such a large surge current may contact the general power switch or relay contact melting,and the input fuse fuse.In addition,the capacitor surge current will damage to shorten the life span of premature damage.To this end,the boot should be access to a current limiting resistor,through the current limiting resistor to capacitor charging.In order not to make the current limiting resistor excessive power consumption,thus affecting the normal switching regulator,and the transient process in the boot after a short period then automatically relays it to DC power supply directly to the switching regulator power supply.This circuit switching regulator called a"soft start"circuit.Switching regulator control circuit of the logic components required or op-amp auxiliary power supply.To this end,the auxiliary power supply must be in the switch circuit. This control circuit can be used to ensure the boot.Normal boot process is:to identify the polarity of input power,voltage protection procedures→boot→auxiliary power supply circuit and through current limiting resistor R of the switching regulator input capacitor C→charge modulation switching regulator circuit,→short-circuit current limiting resistor stability switching regulator.In the switching regulator,the machines just because the output capacitance,and charge to the rated output voltage value of the need for a certain period of time.During this time, sampling the output amplifier with low input voltage sampling,closed-loop regulation characteristics of the system will force the switching of the transistor conduction time lengthened,so that switching transistor during this period will tend to continuous conduction, and easily damaged.To this end,the requirements of this paragraph in the boot time,the switch to switch the output modulation circuit transistor base drive signal of the pulse width modulation,can guarantee the switching transistor by the cut-off switches are becoming more and more normal state,therefore the protection of the setting up of a boot to tie in with the soft start.4、over-current protectionWhen the load short-circuit,overload control circuit failure or unforeseen circumstances,such as would cause the flow of switching voltage regulator transistor current is too large,so that increased power tubes,fever,if there is no over-current protection device, high power switching transistor may be damaged.Therefore,the switching regulator in the over-current protection is commonly used.The most economical way is to use simple fuse. As a result of the heat capacity of small transistors,general fuse protection in general can not play a role in the rapid fuse common fuse.This method has the advantage of the protectionof vulnerable,but it needs to switch transistor in accordance with specific security requirements of the work area to select the fuse specifications.This disadvantage is over-current protection measures brought about by the inconvenience of frequent replacement of fuses.Linear voltage regulator commonly used in the protection and current limiting to protect the cut-off in the switching regulator can be applied.However,according to the characteristics of switching regulators,the protection circuit can not directly control the output transistor switches,and overcurrent protection must be converted to pulse output commands to control the modulator to protect the transistor switch.In order to achieve over-current protection are generally required sampling resistor in series in the circuit,this will affect the efficiency of power supply,so more for low-power switching regulator of occasions.In the high-power switching power supply,by taking into account the power consumption should be avoided as far as possible access to the sampling resistor.Therefore, there will usually be converted to over-current protection,and under-voltage protection.5、over-voltage protectionSwitching regulator's input over-voltage protection,including over-voltage protection and output over-voltage protection.Switching regulator is not used in DC power supply voltage regulator and rectifier,such as battery voltage,if too high,so switching regulator is not working properly,or even damage to internal devices,therefore,it is necessary to use the input over-voltage protection ing transistors and relays protection circuit.In the circuit,when the input DC power supply voltage higher than the voltage regulator diode breakdown voltage value,the breakdown voltage regulator tube,a current flowing through resistor R,so that V turn-on transistor,relay,normally closed contact off open,cut off the input.Voltage regulator voltage regulator which controls the value of Vz= ESrmax-UBE.The polarity of input power with the input protection circuit can be combined with over-voltage protection,polarity protection constitute a differential circuit and overvoltage protection.Output over-voltage protection switching power supply is essential.In particular,for the5V output of the switching regulator,it is a lot of load on a high level of integration of the logic device.If at work,switching regulator sudden damage to the switch transistor,the output potential may be increased immediately to the importation of non-regulated DC power supply voltage value,causing great loss monly used method isshort-circuit protection thyristor.The simplest over-voltage protection circuit.When the output voltage is too high,the regulator tube breakdown triggered thyristor turn-on,the output short-circuit,resulting in over-current through the fuse or circuit protective device to cut off the input to protect the load.This circuit is equivalent to the response time of the opening time of thyristor is about5~10μs.The disadvantage is that its action is fixed voltage,temperature coefficient,and action points of instability.In addition,there is a voltage regulator control parameters of the discrete,model over-voltage start-up the same but has different values,difficult to debug.Esc a sudden increase in output voltage, transistors V1,V2conduction,the thyristor conduction.Reference voltage Vz by type.6、under-voltage protectionOutput voltage below the value to reflect the input DC power supply,switching regulator output load internal or unusual occurrence.Input DC power supply voltage drops below the specified value would result in switching regulator output voltage drops,the input current increases,not only endanger the switching transistor,but also endanger the input power.Therefore,in order to set up due to voltage protection.Due to simple voltage protection.When no voltage regulator input normal,ZD breakdown voltage regulator tube, transistors V conduction,the relay action,contact pull-in,power-switching regulator.When the input below the minimum allowable voltage value,the regulator tube ZD barrier,V cut-off,contact Kai-hop,switching regulator can not work.Internal switching regulator,as the control switch transistor circuit disorders or failure will decrease the output voltage;load short-circuit output voltage will also decline.Especially in the reversed-phase step-up or step-up switching regulator DC voltage of the protection due to over-current protection with closely related and therefore more important.Implementation of Switching Regulators in the termination of the output voltage comparators.Normally,there is no comparator output,once the voltage drops below the allowable value in the comparator on the flip,drive alarm circuit;also fed back to the switching regulator control circuit,so that switching transistor cut-off or cut off the input power.7、over-temperature protectionSwitching regulator and the high level of integration of light-weight small volume,with its unit volume greatly increased the power density,power supply components to its workwithin the requirements of the ambient temperature is also a corresponding increase. Otherwise,the circuit performance will deteriorate,premature component failure.Therefore, in high-power switching regulator should be set up over-temperature protection.Relays used to detect the temperature inside the power supply temperature,when the internally generated power supply overheating,the temperature of the relay on the action,so that whole circuit in a warning alarm,and the realization of the power supply over-temperature protection.Temperature relay can be placed in the vicinity of the switching transistor,the general high-power tube shell to allow the maximum temperature is75℃, adjust the temperature setting to60℃.When the shell after the temperature exceeds the allowable value to cut off electrical relay on the switch protection.Semiconductor switching device thermal"hot thyristor,"in the over-temperature protection,played an important role. It can be used as directed circuit temperature.Under the control of p-hot-gate thyristor (TT102)characteristics,by RT value to determine the temperature of the device turn-on,RT greater the temperature the lower the turn-on.When placed near the power switching transistor or power device,it will be able to play the role of temperature instructions.When the power control the temperature of the shell or the internal device temperature exceeds the allowed value,the heat conduction thyristor on,so that LED warning light.If the optocoupler with,would enable the whole circuit alarm action to protect the switching regulator.It can also be used as a power transistor as the over-temperature protection,crystal switch the base current by n-type gate control thyristor TT201thermal bypass,cut-off switch to cut off the collector current to prevent overheating.8、ConclusionDiscussed above in the switching regulator of a variety of conservation,and introduces a number of specific ways to achieve.Of a given switching power supply is concerned,but also protection from the whole to consider the following points:1)the switching regulator used in the switching transistor in the DC security restrictions on the work of regional work.The transistor switches selected by the manual available transistors get DC safe working area.According to the maximum collector current to determine the input value of over-current protection.However,the instantaneous maximum value should be converted to the average current.At rated output current and output voltage conditions,the switch of the dynamic load line does not exceed a safe working area DC maximum input voltage,input over-voltage protection is the voltage value.2)the switching regulator output limit given by the technical indicators within.Work within the required temperature range,the switching regulator's output voltage,the lower limit of the output is off,due to the voltage value of voltage protection.Over-current protection can be based on the maximum output current to determine.False alarm in order not to protect the value of a certain margin to remain appropriate.3)from the above two methods to determine the protection after the power supply device in accordance with the needs of measures to determine the alarm.Measures the general alarm sound and light alarm two police.Voice of the police applied to more complex machines,power supply parts and do not stand out in a place,it can give staff an effective warning of failure;optical Police instructions can be eye-catching and fault alarm and pointed out that the fault location and type.Protection measures should be protected as to determine the location.In the high-power,multi-channel power supply,always paying,DC circuit breakers,relays,etc.high-sensitivity auto-protection measures,to cut off the input power supply to stop working the system from damage.Through the logic control circuit to make the appropriate program cut-off switch transistor is sensitive it is convenient and economic.This eliminated large,long response time,the price of your high-power relay or circuit breaker.4)the power of putting in the protection circuit will be affected after the reliability of the system,for which want to protect the reliability of the circuit itself is higher in order to improve the reliability of the entire power system,thereby increasing its own power supply MTBF.This requires the protection of strict logic,the circuit is simple,at least components, In addition to the protection circuit should also be considered a failure of maintenance of their difficulty and their power to protect the damage.Therefore,we must be comprehensive and systematic consideration of a variety of switching power supply protection measures to ensure the normal operation of switching power supplies and high-efficiency and high reliability.。

仓储物流外文文献翻译中英文原文及译文2023-2023

仓储物流外文文献翻译中英文原文及译文2023-2023原文1：The Current Trends in Warehouse Management and LogisticsWarehouse management is an essential component of any supply chain and plays a crucial role in the overall efficiency and effectiveness of logistics operations. With the rapid advancement of technology and changing customer demands, the field of warehouse management and logistics has seen several trends emerge in recent years.One significant trend is the increasing adoption of automation and robotics in warehouse operations. Automated systems such as conveyor belts, robotic pickers, and driverless vehicles have revolutionized the way warehouses function. These technologies not only improve accuracy and speed but also reduce labor costs and increase safety.Another trend is the implementation of real-time tracking and visibility systems. Through the use of RFID (radio-frequency identification) tags and GPS (global positioning system) technology, warehouse managers can monitor the movement of goods throughout the entire supply chain. This level of visibility enables better inventory management, reduces stockouts, and improves customer satisfaction.Additionally, there is a growing focus on sustainability in warehouse management and logistics. Many companies are implementing environmentally friendly practices such as energy-efficient lighting, recycling programs, and alternativetransportation methods. These initiatives not only contribute to reducing carbon emissions but also result in cost savings and improved brand image.Furthermore, artificial intelligence (AI) and machine learning have become integral parts of warehouse management. AI-powered systems can analyze large volumes of data to optimize inventory levels, forecast demand accurately, and improve operational efficiency. Machine learning algorithms can also identify patterns and anomalies, enabling proactive maintenance and minimizing downtime.In conclusion, warehouse management and logistics are continuously evolving fields, driven by technological advancements and changing market demands. The trends discussed in this article highlight the importance of adopting innovative solutions to enhance efficiency, visibility, sustainability, and overall performance in warehouse operations.译文1：仓储物流管理的当前趋势仓储物流管理是任何供应链的重要组成部分，并在物流运营的整体效率和效力中发挥着至关重要的作用。

机械类外文文献翻译(中英文翻译)

机械类外文文献翻译(中英文翻译)英文原文Mechanical Design and Manufacturing ProcessesMechanical design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product.People who perform the various functions of mechanical design are typically called designers, or design engineers. Mechanical design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes.As stated previously, the purpose of mechanical design is to produce a product which will serve a need for man. Inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed.Mechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product, to analyze the systemand then make sound judgments on how the product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions required to produce a good design.On the other hand, any calculations made must be done with the utmost care and precision. For example, if a decimal point is misplaced, an otherwise acceptable design may not function.Good designs require trying new ideas and being willing to take a certain amount of risk, knowing that if the new idea does not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.New designs generally have "bugs" or unforeseen problems which must be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.During the beginning stages of design, creativity should be allowedto flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before firm details are required by manufacturing. In this way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise.Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the design engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum.Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated. Communicating the design to others is the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.Basically, there are only three means of communication available tous. These are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, no one will ever know how competent that person is!The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great deal to be learned from a failure, and the greatest gains are obtained by those willing to risk defeat. In the final analysis, the real failure would lie in deciding not to make the presentation at all. To communicate effectively, the following questions must be answered:(1) Does the design really serve a human need?(2) Will it be competitive with existing products of rival companies?(3) Is it economical to produce?(4) Can it be readily maintained?(5) Will it sell and make a profit?Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings.Quite often, a problem will occur during the manufacturing cycle [3].It may be that a change is required in the dimensioning or tolerancing of a part so that it can be more readily produced. This fails in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. These realities simply bear out the fact that design is a living process. There is always a better way to do it and the designer should constantly strive towards finding that better way.Designing starts with a need, real or imagined. Existing apparatus may need improvements in durability, efficiently, weight, speed, or cost. New apparatus may be needed to perform a function previously done by men, such as computation, assembly, or servicing. With the objective wholly or partly defined, the next step in design is the conception of mechanisms and their arrangements that will perform the needed functions.For this, freehand sketching is of great value, not only as a record of one's thoughts and as an aid in discussion with others, but particularly for communication with one's own mind, as a stimulant for creative ideas.When the general shape and a few dimensions of the several components become apparent, analysis can begin in earnest. The analysis will have as its objective satisfactory or superior performance, plus safety and durability with minimum weight, and a competitive east. Optimum proportions and dimensions will be sought for each critically loaded section, together with a balance between the strength of the several components. Materials and their treatment will be chosen. These important objectives can be attained only by analysis based upon the principles ofmechanics, such as those of statics for reaction forces and for the optimumutilization of friction; of dynamics for inertia, acceleration, and energy; of elasticity and strength of materials for stress。

应收账款【外文翻译】

外文文献翻译一、外文原文原文：Accounts Receivable IssuesFor many companies, the accounts receivable portfolio is its largest asset. Thus, it deserves special care and attention. Effective handling of the portfolio can add to the bottom line, while neglect can cost companies in unseen losses.Accounts Receivable Strategies to Energize the Bottom LineDon’t be surprised to find the big shots from finance suddenly looking over your shoulder questioning the ways your credit department operates. Accounts receivable has become the darling of those executives desperate to optimize working capital and improve their balance sheet.Here’s a roundup of some of the tactics that have been collected from the best credit managers to squeeze every last cent out of their accounts receivable portfolio: ·Have invoices printed and mailed as quickly as possible. Most customers start the clock ticking when the invoice arrives in their offices. The sooner you can get the invoice to them, the sooner they will pay you. While this strategy will not affect days sales outstanding(DSO),it will improve the bottom line.·Look for ways to improve invoice accuracy without delaying the mail date.·Offer more stringent terms where appropriate in your annual credit reviews and with new customers. Consider whether shorter terms might be better for you company.·Offer financial inducements to customers who agree to pay your invoices electronically.·If you have not had a lockbox study performed in the last few years, have one done to determine your optimal lockbox location.·With customers who have a history of paying late, begin your collection effortsbefore the due date. Call to inquire whether they have the invoice and if everything is in order. Resolve any problems quickly at this point.·If you have been giving a grace period to those taking discounts after the discount period, reduce or eliminate it.·Resolve all discrepancies quickly so payment can be made promptly.·If a customer indicates it has a problem with part of an invoice, authorize partial payments.·Keep a log of customer problems and analyze it once a month to discover weaknesses in your procedures that cause these quandaries.·Apply cash the same day the payment is received. Collectors can then spend their time with customers who have not paid rather than annoying ones who have already sent their payment.·Deal with a bank that makes lockbox information available immediately by fax, or preferably, online. Then when a customer claims it has made a payment , the collector will be able to verify this.·Look into ways to accept P-cards from customers placing small orders and those who cannot be extended credit on open account terms.·Benchmark department and individual collectors’ performance to pinpoint those areas and individuals in need of additional training.Review your own policies and procedures to determine if there are any areas that could be tweaked to improve cash flow. Then, when the call comes from executive quarters, you will be ready, and they will be hard pressed to find ways that you fell down on the job.Dealing with Purchase OrdersLeading credit managers have learned to pay attention to the purchase orders that their companies receive. Specifically, they want to ensure that the purchase order accepted by the salesperson does not include clause that will ultimately cause trouble for their companies, or even legal difficulties later on. Realistically, the salesperson should have caught the problem, but he or she rarely does. When the customer doesn’tpay due to one of these techn icalities, it’s not the salesperson who will get blamed.To help avoid a purchase order disaster, credit professionals can take the following steps:1．Simply read the purchase order. Vendors often slip clauses into purchase orders that you would never agree to. One favorite is to include a statementsaying the seller will be paid as soon as its customer pays the buyer. This is arisk few companies are willing to tolerate.2．Prioritize attachments. Typically, buyers write purchase orders that contain attachments. These include drawings, specifications, supplementary termsand conditions for work done on company premises, or safety rules for thesupplier.When including attachments, it is recommended that one of them be a listof priorities to guard against any inconsistencies in the documents. Thepurchase order should “clearly reference all the attachments, and there shouldbe a recitation as to which attachments are controlling over the others.” In theevent of any inconsistency between or among these documents, the purchaseorder shall be controlling over any attachments, and the attachments shall beinterpreted using the priority listed.3．Take care when reference is made to a buyer’s documents in the purchase order. There are likely to be both helpful and harmful statements in thosedocuments that reference the buyer’s material. The buyer may have printedits own terms and conditions on the back of a document. By referring to thedocument in the purchase order, you may inadvertently refer not only to theprice, but also to terms and conditions, which may include warrantydisclaimers and limitations of remedies that your company does not intend togive.Instead, the recommendation is not to refer to the buyers’ documents.Insist that the information is specified in the purchase order. If this is notpractical, the following language might work:” Any reference to thepurchaser’s quotation contained in this purchase order is a reference forconvenience only, and no such reference shall be deemed to include any ofthe purchaser’s standard terms and conditions of sale. The seller expresslyrejects anything in any of the buyer’s documents that is inconsistent with theseller’s standard terms and conditions.”Another favorite is to include terms and conditions on the back of thepurchase order written in very small print and a pale (almost undecipherable)color.4．Be careful of confirming purchase orders. Often, buyers will place orders via telephone, only to later confirm them with a written purchase order. In oralcontracts, the buyer will often want the purchase order to be more than justan offer. Therefore, the buyer will try to show on the purchase order that it isa confirming purchase order and cement the oral contract made over thephone. If the buyer does so, the confirming purchase order will satisfy theUniform Commerical Code (UCC) requirement of a written confirmationunless the other side objects to it within ten days.More than one cunning purchaser has slipped terms into a confirmingpurchase order that were nothing like those agreed to orally. Don’t fall intothe trap of assuming that the confirming purchase order confirms what wasactually said on the phone.Credit professionals who take these few extra steps with regard to purchase orders will limit their troubles.Quality of Accounts Receivable: Days Sales OutstandingMany credit professionals are measured on their effectiveness by reviewing the accounts receivable portfolio. The most common measurement is the length of time a sale stays outstanding before being paid. The Credit Research Foundation (CRF) defines DSO as the average time in days that receivables are outstanding. It helps determine if a change in receivables is due to a change in sales, or to another factor such as a change in selling terms. An analyst might compare the day’s sales in receivables with the company’s credit terms as an indication of how efficiently thecompany manages its receivables. Days sales outstanding is occasionally referred to as days receivable outstanding, as well. The formula to calculate DSO is:365e Re Sales t N Annual ceivablesGrossQuality of Accounts Receivable: Collection Effectiveness IndexSome feel that the quality of the portfolio is dependent to a large extent on the efforts of the collection staff. This is measured by the collection effectiveness index (CEI). The CRF says this percentage expresses the effectiveness of collection efforts over time. The closer to 100% the ratio gets, the more effective the collection effort. It is a measure of the quality of collection of receivables, not of time. Here’s the formula to calculate the CEI:Daysor Months of Number N ceivables Current Ending N Sales Credit ceivables Beginning ceivablesTotal Ending N Sales Credit ceivables Beginning =⨯-+-+100Re )(Re Re )(ReQuality of Accounts Receivable: Best Possible Days Sales OutstandingMany credit professionals find fault with using DSO to measure theirperformance. They feel that a better measure is one based on average terms based on customer payment patterns. The CRF says that this figure expresses the best possible level of receivables. The CRF believes this measure should be used together with DSO. The closer the overall DSO is to the average terms based on customer payment patterns (best possible DSO [BPDSO])，the closer the receivables are to the optimal level. The formula for calculating BPDSO is:AnalyzedPeriod for Sales Credit Analyzed Period in Days of Number ceivables Current ⨯ReBad-Debt ReservesInevitably, no matter how good the credit professional, a company will have a customer that does not pay its debts. Most companies understand that bad debts are simply part of doing business and reserve for bad debts. In fact, many believe that acompany with no bad debts is not doing a good job. The reason that being that if the company loosened its credit terms slightly, the company would greatly increase its sales and, even after accounting for the bad debts, its profits. Thus, most companies plan for bad debt, monitor it, and periodically, depending on the company’s outlook, revise projections and credit policy to allow for an increase or decrease.For example, as the economy goes into a recession, most companies will experience an increase in bad debts if their credit policy remains static. So, in light of declining economic conditions, companies should either increase their bad-debt reserves or tighten the credit policy. Similarly, if the economy is improving, a company would take reverse actions, either decreasing the reserve for bad debts or loosening the credit policy.Many companies take advantage or a favorable economy to expand their customer base. They might simultaneously increase the bad-debt reserve and loosen credit policy. Obviously, these decisions are typically made at a fairly high level. Other factors will also come into play in establishing a bad-debt reserve. Industry conditions are key and can often be quite different than the state of the economy. This is especially true when competition comes from foreign markets.There is no one set way to calculate the reserve for bad debts. Many simply take a percentage of sales or outstanding accounts receivable, or they make some other relatively uncomplicated calculation.How to Reduce Your Bad-Debt Write-OffsMost credit and collection professionals would love to be able to brag about having no bad-debt write-offs. Few can. While a goal of reducing the amount of bad debt write-offs to zero might be unrealistic in most industries, keeping that number as low as possible is something within the control of today’s credit managers. The following seven techniques will help you keep your numbers as low as possible:1.Call early. Don’t wait until the ac count goes 30 or even 60 days past duebefore calling customers about late payments. Such delays can mean that, in the case of a financially unstable company, a second and perhaps even a thirdshipment will be made to a customer who ultimately will pay for naught. Some professionals even call a few days before the payment is due to ensure that everything is in order and the customer has everything it needs to make a timely payment. By beginning your calling campaign as early as possible, it is possible o uncover shaky situations. Even if payment is not received for the first delivery, future order are not accepted, effectively reducing bad-debt write-offs.municate, communicate, communicate. Keep the dialogue open with everyone involved. This not only includes your customers, but the sales force as well. In many cases, they are in a better position than the credit manager to know when a customer is on thin ice. With good lines of communication between sales and credit, it is possible to avoid taking some of those orders that will ultimately have to be written off.3.Follow up, follow up, follow up. Continual follow up with customers is important, whether you’re trying to collect on a timely basis or attempting to avoid a bad-debt write-off. If the customer knows you will call every few days or will be calling to track the status of promises made, it is much more likely to pay. This can also be the case of the squeaky wheel getting the grease, or in this case the money, when cash is tight.4.Systematize. Many collection professionals keep track of promises and deadlines by hand, on a pad or calendar. Items tend to fall through the cracks with this approach. Invest some money either in prepackaged software or in developing your own in-house, and the likelihood of losing track of customers diminishes. Some accounting programs have a tracking capability that many have not taken the time to learn. If your software has such a facility, use it.5.Specialize. Set up a group of one or more individuals who do nothing but try to collect receivables that are overdue. By having experts on staff to handle such work, you will improve your collection rate and speed.6.Credit hold. Putting customers on credit hole early in the picture will sometimes entice a payment from someone who really had no intention of paying you. This technique is particularly effective with customers who rely heavily onyour product and would be hard put to get it elsewhere. Of course, if you sell something that many other vendors sell as well, putting a potentially good customer on hold could backfire.7.Small claims court. Some credit professionals have had great success incollecting smaller amounts by taking the customer to small claims court. The limits for such actions vary by state but can be as high as $10,000.While these techniques will not necessarily squeeze money from a bankrupt client, they will help you get as much as possible as soon as possible from as many of your customers as possible. This can be especially important in avoiding preference actions with clients who eventually do file. The quicker you get the clock ticking, the more likely you are to be able to avoid preference claims.Source: Mary S. Schaeffer, 2002, Essentials of Credit, Collections, and Accounts Receivable, John Wiley & Sons, Inc.( October 01, 2002 ):pp81-102.二、翻译文章译文：应收账款对许多公司来说，应收账款是其最大的资产。

外文翻译原文

Project Management ProcessDurgesh BurdeAbstract:There are the rules of project management. Project management skills are indispensable for project managers, and other managers who control intricate actions and responsibilities, because intricate responsibilities are projects. Project management skills are necessary for any intricate responsibility, where diverse results are feasible, requiring plan and assess alternatives, and organizing actions and assets to deliver an outcome. Projects arrive in all forms and dimensions, from the little and simple to extremely big and highly intricate. Project management may be concerned with everything such as:- public, products, finance, buildings and premises, acquisition, services, purchasing, resources, construction, plant and equipment, training, culture, divestment, storage, distribution, logistics, IT and communications, staffing and management, administration, sales, selling, marketing, human resources, etc. Project management, for projects large or small, should follow the simple process:Project management process1.Detailed requirement for the project.2.Plan the project - time, team, activities, resources, and financials.3.Correspond the project plan to the project group.4.Consent and allot project actions.5.Control, encourage, notify, promote, and facilitate the project team.6.Verify, assess, evaluate project development; regulate project procedure, andnotify the project members and others.7.Finish project; evaluation and report on project performance; Admire and thanksto the project members.1. Detailed requirement for the projectFrequently called the project 'terms of reference', the project requirement should be an exact depiction of what the project aspires to accomplish, and the criteria and flexibilities concerned, its factors, scope, range, outputs, sources, participants, budgets and timescales.The project manager must discuss with others and then consent the project requirement with superiors, or with relevant authorities. The requirement may engage several drafts before it is agreed. A project requirement is essential in that it creates a measurable accountability for anyone wishing at any time to assess how the project is going, or its success on completion. Project terms of reference also provide an essential discipline and framework to keep the project on track, and concerned with the original agreed aims and parameters. A properly formulated and agreed project requirement also protects the project manager from being held to account for issues that are outside the original scope of the project or beyond the project manager's control.This is the step to agree special circumstances or exceptions with those in authority. Once you have published the terms of reference you have created a very firm set of expectations by which you will be judged. So if you have any concerns, or want to renegotiate, now's the time to do it.The largest projects can require several weeks to produce and agree project terms of reference. Most normal business projects however require a few days thinking and consulting to produce a suitable project requirement. Establishing and agreeing a project requirement is an important process even if your task is simple one.An outline for a project requirement:1.Describe purpose, aims and deliverables.2.State factors (timescales, budgets, range, scope, territory, authority).3.State people involved and the way the team will work (frequency of meetings,decision-making process).4.Establish 'break-points' at which to review and check progress, and how progressand results will be measured.2. Plan the project - time, team, activities, resources, and financials.Plan the various steps and tasks of the project. A valuable tip is to work backwards from the end aim, identifying all the things that need to be put in place and done, in reverse order. First, idea generation will help to gather most of the points and issues. For complex projects, or when you lack experience of the issues, involve others in the idea generation process. Thereafter it is a question of putting the issues in the right order, and establishing relationships and links between each issue. Complex projects will have a number of tasks running in parallel. Some parts of the project will need other parts of the project to be completed before they can begin or progress. Some projects will require a feasibility step before the completion of a detailed plan.a) Project timescalesMost projects come in late - that is just the way it is - so do not plan a timescale that is over-ambitious. Preferably, plan for some adversaries. If you have been given a fixed deadline, plan to meet it earlier, and work back from that earlier date. Build some slippage or leeway into each phase of the project. Err on the side of caution where you can. Otherwise, you will be making a rod for your own back.b) The project teamAnother important part of the planning stage is picking your team. Take great care, especially if you have team-members imposed on you by the project brief. Selecting and gaining commitment from the best team members - whether directly employed, freelance, contractors, suppliers, consultants or other partners - is crucial to the quality of the project, and the ease with which you are able to manage it. Generally try to establish yourteam as soon as possible. Identifying or appointing one or two people even during the terms of reference stage is possible sometimes. Appointing the team early maximizes their ownership and buy-in to the project, and maximizes what they can contribute. But be very cautious of appointing people before you are sure how good they are, and not until they have committed themselves to the project upon terms that are clearly understood and acceptable. Do not imagine that teams need to be full of paid and official project team members. Some of the most valuable team members are informal advisors, mentors, helpers, who want nothing other than to be involved and a few words of thanks. Project management on a tight budget can be a lonely business - get some help from good people you can trust, whatever the budget.To plan and manage large complex projects with various parallel and dependent tasks you will need to put together a 'Critical Path Analysis' and a spreadsheet on MS Excel or equivalent. Critical Path Analysis will show you the order in which tasks must be performed, and the relative importance of tasks. Some tasks can appear small and insignificant when they might actually be hugely influential in enabling much bigger activities to proceed or give best results. A Gantt chart is a useful way of showing blocks of activities over time, at a given cost, and for managing the project and its costs along the way.Various project management software is available, much of which is useful, but before trying it, you should understand and concentrate on developing the pure project management skills, which are described in this process. The best software in the world will not help you if you cannot do the key things.c) The project 'critical path analysis''Critical Path Analysis' sounds very complicated, but it's a very logical and effective method for planning and managing complex projects. This is how to create a critical path analysis. As an example, the project is a simple one - making a fried breakfast.First note down all the issues (resources and activities in a rough order):Assemble crockery and utensils, assemble ingredients, prepare equipment, make toast, fry sausages and eggs, grill bacon and tomatoes, lay table, warm plates, serve.Note that some of these activities must happen in parallel. That is to say, if you tried to make a fried breakfast by doing one task at a time, and one after the other, things would go wrong. Certain tasks must be started before others, and certain tasks must be completed in order for others to begin. The plates need to be warming while other activities are going on. The toast needs to be toasting while the sausages are frying, and at the same time the bacon and sausages are under the grill. The eggs need to be fried last. A critical path analysis is a diagrammatical representation of what needs done and when. Timescales and costs can be applied to each activity and resource. Here's the critical path analysis for making a fried breakfast:This critical path analysis example below shows just a few activities over a few minutes. Normal business projects would see the analysis extending several times wider than this example, and the time line would be based on weeks or months. It is possible to use MS Excel or a similar spreadsheet to create a critical path analysis, which allows financial totals and time totals to be planned and tracked. Various specialized project management software enable the same thing. Beware however of spending weeks on the intricacies of computer modeling, when in the early stages especially, a carefully hand drawn diagram - which requires no computer training at all - can put 90% of the thinking and structure in place.d) Gantt chartsGantt Charts are extremely useful project management tools. You can construct a Gantt Chart using MSExcel or a similar spreadsheet. Every activity has a separate line. Create a time-line for the duration of the project (the breakfast example shows minutes, but normally you would use weeks, or for very big long-term projects, months). You can colour code the time blocks to denote type of activity (e.g. intense, watching brief, directly managed, delegated and left to run, etc.) You can schedule review and break points. At the end of each line you can show as many cost columns for the activities as you need. The breakfast example shows just the capital cost of the consumable items and a revenue cost for labour and fuel. A Gantt chart like this can be used to keep track of progress for each activity and how the costs are running. You can move the time blocks around to report on actuals versus planned, and to re-schedule, and to create new plan updates. Costs columns can show plan and actuals and variances, and calculate whatever totals, averages, ratios, etc you need. Gantt Charts are the most flexible and useful of all project management tools, but remember they do not show the importance and inter-dependence of related parallel activities, and they will not show the necessity to complete one task before another can begin, as a critical path analysis will do, so you need both tools, especially at the planning stage.e) Project financial planning and reportingFor projects, involving more than petty cash you will need a spreadsheet to plan and report planned and actual expenditure. Use MSExcel or similar. If you do not know how to put together a basic financial plan, get some help from someone who knows. Make sure you bring a good friendly, flexible financial person into your team - it is a key function of project management, and if you cannot manage the financial processes your self, you need to be able to rely completely on whoever does it for you. The spreadsheet must enable you to plan, administer and report the detailed finances of your project. Create a cost line for main expenditure activity, and break this down into individual elements. Create a system for allocating incoming invoices to the correct activities (your bought-ledger people will not know unless you tell them), and showing when the costs hit the project account. Establish clear payment terms with all suppliers and stick to them. Projects develop problems when team members get dissatisfied; rest assured, non- or late-payment is a primary cause of dissatisfaction.Remember to set some budget aside for 'contingencies' - you will need it.f) Project contingency planningPlanning for and anticipating the unforeseen, or the possibility that things may not go as expected, is called 'contingency planning'. Contingency planning is vital in any task when results and outcomes cannot be absolutely guaranteed. Often a contingency budget needs to be planned, as there are usually costs associated. Contingency planning is about preparing fallback actions, and making sure that leeway for time, activity and resource exists to rectify or replace first-choice plans. A simple contingency plan for the fried breakfast would be to plan for the possibility of breaking the yolk of an egg, in which case spare resource (eggs) should be budgeted for and available if needed. Another might be to prepare some hash browns and mushrooms in the event that any of the diners are vegetarian. It may be difficult to anticipate precisely what contingency to plan for in complex long-term projects, in which case simply a contingency budget is provided, to be allocated later when and if required.3. Correspond the project plan to the project group.This serves two purposes: it informs people what is happening, and it obtains essential support, agreement and commitment. If your project is complex and involves a team, then you should involve the team in the planning process to maximize buy-in, ownership, and thereby accountability. Your project will also benefit from input and consultation from relevant people at an early stage.4. Consent and allot project actions.Your plan will have identified those responsible for each activity. Activities need to be very clearly described, including all relevant parameters, timescales, costs, and deliverables. When delegated tasks fail this is typically because they have not been explained clearly, agreed with the other person, or supported and checked while in progress. So publish the full plan to all in the team, but do not issue all the tasks unless the recipients are capable of their own forward planning. Long-term complex projects need to be planned in more detail and great care must be taken in delegating and supporting them. Do not delegate anything unless it makes sure for perfection.5. Control, encourage, notify, promote, and facilitate the project team.Manage the team and activities by meeting, communicating, supporting, and helping with decisions. Admire vociferously; charge quietly. One of the big challenges for a project manager is deciding how much freedom to give for each delegated activity. Tight parameters and lots of checking are necessary for inexperienced people who like clear instructions, but this approach is the kiss of death to experienced, entrepreneurial and creative people. They need a wider brief, more freedom, and less checking. Manage these people by the results they get - not how they get them. Look out for differences in personality and working styles in your team. They can get in the way of understandingand cooperation. Your role here is to enable and translate. Face to face meetings, when you can bring team members together, are generally the best way to avoid issues and relationships becoming personalized and emotional. Communicate progress and successes regularly to everyone. Give the people in your team the applause, particularly when someone high up expresses satisfaction - You must take the blame for anything that goes wrong - never dump on anyone in your team.6. Verify, assess, evaluate project development; regulate project procedure, and notify the project members and others.Check the progress of activities against the plan. Review performance regularly and at the stipulated review points, and confirm the validity and relevance of the remainder of the plan. Adjust the plan if necessary in light of performance, changing circumstances, and new information, but remain on track and within the original terms of reference. Be sure to use transparent, pre-agreed measurements when judging performance. Identify, agree and delegate new actions as appropriate. Inform team members and those in authority about developments, clearly, concisely and in writing. Plan team review meetings. Stick to the monitoring systems you established. Probe the apparent situations to get at the real facts. Examine causes and learn from mistakes. Identify reliable advisors and experts in the team and use them. Keep talking to people, and make yourself available to all.7. Finish project; evaluation and report on project performance; Admire and thanks to the project members.At the end of your successful project, hold a review with the team. Ensure you understand what happened and why. Replicate on any failures and mistakes positively, objectively, and without allocating personal blame. Reflect on successes gratefully and realistically. Write a review report, and make observations and recommendations about follow up issues and priorities - there will be plenty.As project manager, to be at the end of a project and to report that the project plan has been fully met, on time and on budget, is a significant achievement, whatever the project size and complexity. The mix of skills required is such that good project managers can manage anything.Conclusions:Businesses sometimes use formal systems development processes. These help assure that systems are developed successfully. A formal process is more effective in creating strong controls, and auditors should review this process to confirm that it is well designed and is followed in practice. A good formal systems development plan outlines: • A strategy to align development with the organization’s broader objectives•Standards for new systems•Project management policies for timing and budgeting•Procedures describing the processRegardless of the methodology used, the project development process will have the same above major stages: requirement for the project, Plan the project, project group, project actions, project team, evaluate project development, regulate project procedure and finish project; evaluation and report on project performance; Admire and thanks to the project members.References:1.Project Management Guidebook2.How to Manage Projects, Priorites and Deadlines3.Project Manager Today, January 2008.4.The Big Project, July 2008.<><><><><><><><><><><><><><><><>><><><><><><>><><><><><><><><> © Durgesh Burde. The author can be reached at durgesh19@ . The author is freelance writer and his area of research is project management and human development.。

儿童教育外文翻译文献

儿童教育外文翻译文献(文档含中英文对照即英文原文和中文翻译)原文：The Role of Parents and Community in the Educationof the Japanese ChildHeidi KnipprathAbstractIn Japan, there has been an increased concern about family and community participation in the child’s educat ion. Traditionally, the role of parents and community in Japan has been one of support and less one of active involvement in school learning. Since the government commenced education reforms in the last quarter of the 20th century, a more active role for parents and the community in education has been encouraged. These reforms have been inspired by the need to tackle various problems that had arisen, such as the perceived harmful elements of society’spreoccupation with academic achievement and the problematic behavior of young people. In this paper, the following issues are examined: (1) education policy and reform measures with regard to parent and community involvement in the child’s education; (2) the state of parent and community involvement at the eve of the 20th century.Key Words: active involvement, community, education reform, Japan, parents, partnership, schooling, supportIntroduction: The Discourse on the Achievement GapWhen western observers are tempted to explain why Japanese students attain high achievement scores in international comparative assessment studies, they are likely to address the role of parents and in particular of the mother in the education of the child. Education mom is a phrase often brought forth in the discourse on Japanese education to depict the Japanese mother as being a pushy, and demanding home-bound tutor, intensely involved in the child’s education due to severe academic competition. Although this image of the Japanese mother is a stereotype spread by the popular mass media in Japan and abroad, and the extent by which Japanese mothers are absorbed in their children is exaggerated (Benjamin, 1997, p. 16; Cummings, 1989, p. 297; Stevenson & Stigler, 1992, p. 82), Stevenson and Stigler (1992) argue that Japanese parents do play an indispensable role in the academic performance of their children. During their longitudinal and cross-national research project, they and their collaborators observed that Japanese first and fifth graders persistently achieved higher on math tests than American children. Besides reciting teacher’s teaching style, cultural beliefs, and organization of schooling, Stevenson and Stigler (1992) mention parent’s role in supporting the learning conditions of the child to explain differences in achievement between elementary school students of the United States and students of Japan. In Japan, children receive more help at home with schoolwork (Chen & Stevenson, 1989; Stevenson & Stigler, 1992), and tend to perform less household chores than children in the USA (Stevenson et al., 1990; Stevenson & Stigler, 1992). More Japanese parents than American parents provide space and a personal desk and purchase workbooks for their children to supplement their regular text-books at school (Stevenson et al., 1990; Stevenson & Stigler, 1992). Additionally, Stevenson and Stigler (1992) observed that American mothers are much more readily satisfied with their child’s performance than Asian parents are, have less realistic assessments of their child’s academic perform ance, intelligence, and other personality characteristics, and subsequently have lower standards. Based on their observation of Japanese, Chinese and American parents, children and teachers, Stevenson and Stigler (1992) conclude that American families can increase the academic achievement of their children by strengthening the link between school and home, creating a physical and psychological environment that is conducive to study, and by making realistic assessments and raising standards. Also Benjamin (1997), who performed ‘day-to-day ethnography’ to find out how differences in practice between American and Japanese schools affect differences in outcomes, discusses the relationship between home and school and how the Japanese mother is involved in the academic performance standards reached by Japanese children. She argues that Japanese parents are willing to pay noticeable amounts of money for tutoring in commercial establishments to improve the child’s performance on entrance examinations, to assist in ho mework assignments, to facilitate and support their children’s participation in school requirements and activities, and to check notebooks of teachers on the child’s progress and other school-related messages from the teacher. These booklets are read and written daily by teachers and parents. Teachers regularly provide advice and reminders to parents, and write about homework assignments of the child, special activities and the child’s behavior (Benjamin, 1997, p. 119, p. 1993–1995). Newsletters, parents’ v isits to school, school reports, home visits by the teacher and observation days sustain communication in later years at school. According toBenjamin (1997), schools also inform parents about how to coach their children on proper behavior at home. Shimahara (1986), Hess and Azuma (1991), Lynn (1988) and White (1987) also try to explain national differences in educational achievement. They argue that Japanese mothers succeed in internalizing into their children academic expectations and adaptive dispositions that facilitate an effective teaching strategy, and in socializing the child into a successful person devoted to hard work.Support, Support and SupportEpstein (1995) constructed a framework of six types of involvement of parents and the community in the school: (1) parenting: schools help all families establish home environments to support children as students; (2) communicating: effective forms of school-to-home and home-to-school communications about school programs and children’s progress; (3) volu nteering: schools recruit and organize parents help and support; (4) learning at home: schools provide information and ideas to families about how to help students at home with homework and other curriculum-related activities, decisions and planning; (5) decision making: schools include parents in school decisions, develop parent leaders and representatives; and (6) collaborating with the community: schools integrate resources and services from the community to strengthen school programs, family practices, and student learning and development. All types of involvement mentioned in studies of Japanese education and in the discourse on the roots of the achievement gap belong to one of Epstein’s first four types of involvement: the creation of a conducive learn ing environment (type 4), the expression of high expectations (type 4), assistance in homework (type 4), teachers’ notebooks (type 2), mother’s willingness to facilitate school activities (type3) teachers’ advice about the child’s behavior (type 1), observ ation days by which parents observe their child in the classroom (type 2), and home visits by the teachers (type 1). Thus, when one carefully reads Stevenson and Stigler’s, Benjamin’s and other’s writings about Japanese education and Japanese students’ high achievement level, one notices that parents’ role in the child’s school learning is in particular one of support, expected and solicited by the school. The fifth type (decision making) as well as the sixth type (community involvement) is hardly ever mentioned in the discourse on the achievement gap.In 1997, the OECD’s Center for Educational Research and Innovation conducted a cross-national study to report the actual state of parents as partners in schooling in nine countries, including Japan. In its report, OECD concludes that the involvement of Japanese parents in their schools is strictly limited, and that the basis on which it takes place tends to be controlled by the teacher (OECD, 1997, p. 167). According to OECD (1997), many countries are currently adopting policies to involve families closely in the education of their children because (1) governments are decentralizing their administrations; (2) parents want to be increasingly involved; and (3) because parental involvement is said to be associated with higher achievement in school (p. 9). However, parents in Japan, where students already score highly on international achievement tests, are hardly involved in governance at the national and local level, and communication between school and family tends to be one-way (Benjamin, 1997; Fujita, 1989; OECD, 1997). Also parent–teacher associations (PTA, fubo to kyoshi no kai ) are primarily presumed to be supportive of school learning and not to participate in school governance (cf. OECD, 2001, p. 121). On the directionsof the occupying forces after the second world war, PTA were established in Japanese schools and were considered with the elective education boards to provide parents and the community an opportunity to participate actively in school learning (Hiroki, 1996, p. 88; Nakata, 1996, p. 139). The establishment of PTA and elective education boards are only two examples of numerous reform measures the occupying forces took to decentralize the formal education system and to expand educational opportunities. But after they left the country, the Japanese government was quick to undo liberal education reform measures and reduced the community and parental role in education. The stipulation that PTA should not interfere with personnel and other administrative tasks of schools, and the replacement of elective education boards by appointed ones, let local education boards believe that parents should not get involved with school education at all (Hiroki, 1996, p. 88). Teachers were regarded to be the experts and the parents to be the laymen in education (Hiroki, 1996, p. 89).In sum, studies of Japanese education point into one direction: parental involvement means being supportive, and community involvement is hardly an issue at all. But what is the actual state of parent and community involvement in Japanese schools? Are these descriptions supported by quantitative data?Statistics on Parental and Community InvolvementTo date, statistics of parental and community involvement are rare. How-ever, the school questionnaire of the TIMSS-R study did include some interesting questions that give us a clue about the degree of involvement relatively compared to the degree of involvement in other industrialized countries. The TIMSS-R study measured science and math achievement of eighth graders in 38 countries. Additionally, a survey was held among principals, teachers and students. Principals answered questions relating to school management, school characteristics, and involvement. For convenience, the results of Japan are only compared with the results of those countries with a GNP of 20650 US dollars or higher according to World Bank’s indicators in 1999.Unfortunately, only a very few items on community involvement were measured. According to the data, Japanese principals spend on average almost eight hours per month on representing the school in the community (Table I). Australian and Belgian principals spend slightly more hours and Dutch and Singaporean principals spend slightly less on representing the school and sustaining communication with the community. But when it comes to participation from the community, Japanese schools report a nearly absence of involvement (Table II). Religious groups and the business community have hardly any influence on the curriculum of the school. In contrast, half of the principals report that parents do have an impact in Japan. On one hand, this seems a surprising result when one is reminded of the centralized control of the Ministry of Education. Moreover, this control and the resulting uniform curriculum are often cited as a potential explanation of the high achievement levels in Japan. On the other hand, this extent of parental impact on the curriculum might be an indicator of the pressure parents put on schools to prepare their children appropriately for the entrance exams of senior high schools.In Table III, data on the extent of other types of parental involvement in Japan and other countries are given. In Japan, parental involvement is most common in case of schools volunteering for school projects and programs, and schools expecting parents to make sure that thechild completes his or her homework. The former is together with patrolling the grounds of the school to monitor student behavior most likely materialized through the PTA. The kinds and degree of activities of PTA vary according to the school, but the activities of the most active and well-organized PTA’s of 395 elementary schools investigated by Sumida (2001)range from facilitating sport and recreation for children, teaching greetings, encouraging safe traffic, patrolling the neighborhood, publishing the PTA newspaper to cleaning the school grounds (pp. 289–350). Surprisingly, less Japanese principals expect from the parents to check one’s child’s completion of homework than principals of other countries. In the discourse on the achievement gap, western observers report that parents and families in Japan provide more assistance with their children’s homework than parents and families outside Japan. This apparent contradiction might be the result of the fact that these data are measured at the lower secondary level while investigations of the roots of Japanese students’ high achievement levels focus on childhood education and learning at primary schools. In fact, junior high school students are given less homework in Japan than their peers in other countries and less homework than elementary school students in Japan. Instead, Japanese junior high school students spend more time at cram schools. Finally, Japanese principals also report very low degrees of expectations toward parents with regard to serving as a teacher aid in the classroom, raising funds for the school, assisting teachers on trips, and serving on committees which select school personnel and review school finances. The latter two items measure participation in school governance.In other words, the data support by and large the descriptions of parental of community involvement in Japanese schooling. Parents are requested to be supportive, but not to mount the territory of the teacher nor to be actively involved in governance. Moreover, whilst Japanese principals spend a few hours per month on communication toward the community, involvement from the community with regard to the curriculum is nearly absent, reflecting the nearly absence of accounts of community involvement in studies on Japanese education. However, the reader needs to be reminded that these data are measured at the lower secondary educational level when participation by parents in schooling decreases (Epstein, 1995; OECD, 1997; Osakafu Kyoiku Iinkai, unpublished report). Additionally, the question remains what stakeholders think of the current state of involvement in schooling. Some interesting local data provided by the Osaka Prefecture Education Board shed a light on their opinion.ReferencesBenjamin, G. R. (1997). Japanese lessons. New York: New York University Press.Cave, P. (2003). Educational reform in Japan in the 1990s: ‘Individuality’ and other uncertainties. Comparative Education Review, 37(2), 173–191.Chen, C., & Stevenson, H. W. (1989). Homework: A cross-cultural examination. Child Development, 60(3), 551–561.Chuo Kyoiku Shingikai (1996). 21 seiki o tenbo shita wagakuni no kyoiku no arikata ni tsu-ite [First Report on the Model for Japanese Education in the Perspective of theCummings, W. K. (1989). The American perception of Japanese parative Education, 25(3), 293–302.Epstein, J. L. (1995). School/family/community partnerships. Phi Delta Kappan , 701–712.Fujita, M. (1989). It’s all mother’s fault: childcare and the socialization of working mothers in Japan. The Journal of Japanese Studies , 15(1), 67–91.Harnish, D. L. (1994). Supplemental education in Japan: juku schooling and its implication. Journal of Curriculum Studies , 26(3), 323–334.Hess, R. D., & Azuma, H. (1991). Cultural support for schooling, contrasts between Japanand the United States. Educational Researcher , 20(9), 2–8, 12.Hiroki, K. (1996). Kyoiku ni okeru kodomo, oya, kyoshi, kocho no kenri, gimukankei[Rights and duties of principals, teachers, parents and children in education. InT. Horio & T. Urano (Eds.), Soshiki toshite no gakko [School as an organization](pp. 79–100). Tokyo: Kashiwa Shobo. Ikeda, H. (2000). Chiiki no kyoiku kaikaku [Local education reform]. Osaka: Kaiho Shup-pansha.Kudomi, Y., Hosogane, T., & Inui, A. (1999). The participation of students, parents and the community in promoting school autonomy: case studies in Japan. International Studies in Sociology of Education, 9(3), 275–291.Lynn, R. (1988).Educational achievement in Japan. London: MacMillan Press.Martin, M. O., Mullis, I. V. S., Gonzalez, E. J., Gregory, K. D., Smith, T. A., Chrostowski,S. J., Garden, R. A., & O’Connor, K. M. (2000). TIMSS 1999 Intern ational science report, findings from IEA’s Repeat of the Third International Mathematics and ScienceStudy at the Eight Grade.Chestnut Hill: The International Study Center.Mullis, I. V. S., Martin, M. O., Gonzalez, E. J., Gregory, K. D., Garden, R. A., O’Connor, K. M.,Chrostowski, S. J., & Smith, T. A.. (2000). TIMSS 1999 International mathemat-ics report, findings from IEA’s Repeat of the Third International Mathematics and Science Study at the Eight Grade.Chestnut Hill: The International Study Center. Ministry of Education, Science, Sports and Culture (2000).Japanese government policies in education, science, sports and culture. 1999, educational reform in progress. Tokyo: PrintingBureau, Ministry of Finance.Monbusho Ed. (1999).Heisei 11 nendo, wagakuni no bunkyoshisaku : Susumu kaikaku [Japanese government policies in education, science, sports and culture 1999: Educational reform in progress]. Tokyo: Monbusho.Educational Research for Policy and Practice (2004) 3: 95–107 © Springer 2005DOI 10.1007/s10671-004-5557-6Heidi KnipprathDepartment of MethodologySchool of Business, Public Administration and TechnologyUniversity of Twente P.O. Box 2177500 AE Enschede, The Netherlands译文：家长和社区在日本儿童教育中的作用摘要在日本，人们越来越关心家庭和社区参与到儿童教育中。

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毕业设计外文文献翻译院系：数学与计算机科学学院年级专业：12级数学与应用数学姓名：施钰桢学号：121301025有限维向量空间本文译自：Paul R.Halmos. Finite-Dimensional Vector Spaces. Library of Congress Cataloging in Publication Data, 1916.§2.向量空间现在我们来到了这本书的基本概念这里.有如下的定义，令F是一个数域; F中的元素叫做标量.定义：向量空间V满足以下公理.（A）对于任意的x和y，在V中有唯一确定的向量与它们对应，称为x与y的和，并记作x+ y，满足：（1）交换律，x+ y= y+x.（2）结合律，x+（y+z）=(x+y)+z.（3）在V中存在一个独特的向量0（称为原点），对于任意向量x使得+0.xx=（4）对于任意向量x，V中存在一个向量-x与之对应，使得x+（- x）= 0. （B）对于任意α和x，其中α是一个标量，x是V中的向量，在V中有唯一确定的向量与它们对应，称为α和x的积，记作αx，有如下公式：（1）乘法结合律，α（βx）=（αβ）x.（2）对每个向量x有，1x=x.（C）（1）向量乘法分配律，α（x+ y）=αx+αy.（2）标量乘法分配律，（α+β）x=αx+βx.这些公理在逻辑上不要求是独立的，它们只是其中的一个特性，为了方便我们研究.向量空间V和数域F之间的关系通常被描述为V是F上的向量空间.如果F是实数域R，V被称为实数向量空间;同样，如果F是Q或者是E，我们称V为有理向量空间或复数向量空间.§3.实例在讨论关于公理的影响前，我们举一些例子.在整个操作中我们将一遍又一遍参考这些例子，并利用现有的符号.（1）让1E （=E ）为复数的集合，如果我们令x +y 和αx 为普通的复数加法和乘法，则1E 为复数域上的向量空间.（2）p 为所有多项式的集合，变量t 为复数系.我们解释到复数多项式的加法和乘法能写成向量加法和乘法，就称p 为复数向量空间；原点在多项式p 中恒等于零.这本书的典型例子即实例（1）太过简单实例（2）太复杂.我们再举一个例子，复数向量空间（我们将在后面看到）一般足够为我们所用.（3）设n E ,n =1,2,…, 是所有n 元复数的集合.如果x =（1ξ，...,n ξ）和 y =（1η，...,n η），根据定义,有x +y = (1ξ+1η,…, n ξ+n η),x α= (α1ξ,…, αn ξ),0 = (0,…,0),-x = (-1ξ,…,- n ξ).这些§2中的真理（A ），（B ）与（C ）都很容易满足，所以n E 是一个复数向量空间，被称为n 维复坐标空间.（4）对于每个正整数n ，设n P 为所有多项式的集合（复系数，如实例（2））当维≤n -1时，多项式恒等于零. （通常都是以维来讨论的，这多项式的维是没有定义，所以我们不能说维≤n -1）跟线性运算的解释一样（加法和标量乘法）如（2）n P 是一个复数向量空间.(5)与n E 相近的所有n 维实数为n R ，它跟n E 的加法和标量乘法的定义相同，但现在我们只考虑实数标量α，空间n R 是一个实数向量空间，它会被称为n 维实坐标空间.（6）前述所有实例可以进行推广.例如，（1）中的一个明显的概括，可以说每个所述的数域可以被视为其自身的向量空间.一个常见的推广（3）和（5）是由任意数域F和n维F元素构成集合nF;相同情况下线性运算的正式定义为F=E.（7）根据定义，数域至少具有两个元素;一个是向量空间.由于每个向量空间包含原点，实际上（即除符号）一个向量空间只具有一个向量，这个是最简单的向量空间将用来表示.（8）如果在所有实数域R中，加法和有理实数乘法的定义跟之前是一样的，那么R为实数向量空间.（9）如果在所有复数的集合E中，加法和复实数乘法的定义跟之前是一样的，那么E为复数向量空间. （将此例与（1）对比，他们有很大的不同）§4.评论公理和符号的评论.数域和向量空间的公理存在惊人的相似之处（和同样惊人的差异）.在这两种情况下，公理（A）中描述了该系统的加法结构，公理（B）描述了其乘法结构，公理（C）说明两种结构的联系，（在§1和§2）中的公理（A）的交换律是代数中较为熟悉的术语; （§2）中公理（B）及（C）中承认了标量作为运算的符号.我们顺便提下，如果标量是元素（而不是数域），相应的向量空间的广义概念称为模.特殊实向量空间（如2R和3R）是熟悉的几何图形.似乎在这个阶段坚持R以外的数域显然是没有任何理由的，特别是复数域E.我们希望读者愿意去相信它，我们后面尽量使用复数性质（共轭，代数包闭），并且，我们的研究结果为希尔伯特空间的复数的推广在向量空间中的两个应用程序现代（量子力学）物理和数学中发挥重要的作用.它的一大缺点就是画图难度大.对普通图（阿根图）1E和2R 图是无法区别的，用图形表示似乎是超出人能达到的范围.因此我们不得不使用E和n R，例如将2E称为平面.一些图像语言来区分n最后，我们对符号评论.我们观察到的符号0具有两个含义：一个作为标量，一个作为向量.为了使情况变的不那么糟，我们将在后面引入线性泛函与线性变换来给它下定义.幸运的是，0 的各种解释由此可得知，紧记这句话，我们就不会混淆了.练习1.证明，如果x 和y 是向量，α是一个标量，则下面的关系成立.0),(00),(0),(=∙=-=+αc b xx a00),(=∙x d (观察到相同的符号被用在这个等式的两边;左侧它表示的是标量，右侧它表示的是向量.)(e) 如果αx =0，那么α=0或x =0（或α=0且x =0）(f) –x =(-1) x(g) y +(x -y )=x (这里x -y =x +（-y ）)2. 如果P 是素数，则nP Z 是向量空间（cf. §1，例3）;在这个向量空间里有多少个向量？3. 设V 是所有（命令）对数或实数的集合.如果),(21ξξ=x 和),(21ηη=y 为V 中的元素，有x +y = ），（2211ηξηξ++αx = ），（01αξ 0 =（0,0） -x = ），（21--ξξ在线性操作的这些定义中V 是一个向量空间吗？为什么？4. 有时一个向量空间中的一个子集,本身就是一个向量空间(线性操作已经给出).例如,向量空间3E 和3E 中子集V 组成的向量），，（321ξξξ，有（a ）1ξ是实数（b ）1ξ=0（c ）1ξ=0或2ξ=0（d ）1ξ+2ξ=0（e ）1ξ+2ξ=1在这种情况下V 是向量空间？5. 考虑到向量空间p 和p 中的子集V 组成的向量(多项式)x ,有（a ）x 有3维（b ）2x （0）=x （1）（c ）x （t ）≥0，（0 ≤ t ≤ 1）（d ）x （t ）=x （1-t ），t 取任意数在这种情况下V 是向量空间？§5.线性关系既然我们已经描述了向量空间,我们一定会对空间中的元素关系感到兴趣. 我们对求和符号描述几句.如果一组向量被赋于相应的一组指标i 即为i x ,如果没有必要或者不方便对指标进行详细说明,我们将简单地讲一组向量{i x }.(我们承认相同的向量可能有两个不同的指标与之相对应.因此,应该说,重要的不是向量出现在{i x }中,而是它们是如何出现的.) 如果考虑指标集是有限的,我们就把相应的向量之和记为i i x ∑（或者，可更加明确的记为∑=n1i i x ）.为了避免频繁和繁琐,承认i i x ∑作为一般理论的总结是一个好主意，即使之前没有指标i 作总结,或者更准确地说,即考虑指标集是空的.（当然,在这种情况下是没有向量和，或者更准确地说, {i x }也是空的）.这种“空的和”很显然定义为向量0.定义：如果存在一组相对应的标量{i a },且它们不全为0，使得0=∑ii i x a 则称有限向量组{i x }是线性相关.另一方面,如果使0=∑ii i x a 当且仅当i a =0(对于任意i ),则称{i x }是线性无关.这个定义的说法是指在空集情况下,虽然可能产生矛盾,但其它部分的理论还是相对吻合的.其结果表明，空集向量是线性无关的.实际上,如果没有指标i ,那么从向量中挑出一部分并分配给选定的非零标量使其之和消失是不可能的.问题不在于避免赋值为零,而在于分配指标.注意,这种观点表明,空集不是线性相关;线性无关的定义与直接否定线性相关的定义是等价的，这个说法还是需要一些直观理由.最简单的说法是“0=∑ii i x a 当且仅当i a =0(对于任意i )”.假使没有指标i ，则另有说法：“如果0=∑ii i x a 没有指标i ，则i a ≠0”,如果不存在指标i ，这个版本显然是如此.线性相关和无关是向量集的属性，它是司空见惯的,然而对于向量本身的形容词应用,我们有时会说“一组线性无关的向量”而不是“线性无关的一组向量”.它也可以简单的说向量x 的线性相关和无关，并不一定要是有限集.为了深入了解线性相关的意义，我们用已有的向量空间的例子来学习.(1) 如果x 和y 是1E 中的任意两个向量,则x 和y 是一组线性相关.如果x = y =0，这个并不重要;如果不是这样的,那么我们有y x +(-x )y =0的关系.很明显, 因为每组包含一个线性相关的子集本身就是线性相关,这表明在1E 的各个组中包含多个元素是一组线性相关.(2) 在空间P 情况下，向量y x ,和z 的定义，有,1)(),1()(,1)(2t t z t t t y t t x -=-=-=例如,当x +y -z =0则线性相关.然而对于无限的向量集,,,,210 x x x 的定义，有,,)(,)(,1)(2210 t t x t t x t x ===是一组线性无关的,如果存在形式01100=+++n n x a x a x a那么，我们就得到一个多项式的恒等式：010=+++n n t a t a a由此可得 010====n a a a(3) 正如我们前面提到的,空间n E 是我们要研究的原型,让我们来看看,当n = 3，对于那些熟悉的高维几何,线性相关的概念 (或者,更确切的说,与其类似的(3R ))在这个领域有一个具体的几何意义.我们只提及在几何语言中若两个向量是线性相关的，当且仅当它们是共线.（如果有人认为一个向量不是作为空间中的一个点,而是作为一个箭头指向即从原点指向某个给定的点,由于两次忽略了“原点”，所以前面的句子应该修改下）.我们目前介绍了向量空间中线性流形（或向量子空间）的概念，并在这方面，我们将偶尔使用这类几何语言.§6.线性组合我们说，只要ii i x a x ∑=，则x 是}{i x 一个线性组合;我们将没有任何进一步的解释，能使这个术语的所用语句更加简单.因此我们说,假如x 是}{i x 的线性组合,那么在{}i x 中x 是线性无关的；我们留给读者证明，如果{}i x 是线性无关的，它的充分必要条件是x 是}{i x 的一个线性组合.需要注意的是，按照空的和的定义，原点是空集的线性组合，而且这是此向量的唯一属性.下面的定理是关于线性相关的基本结果.定理：非零向量组)2(,,1n k x x k ≤≤ 是线性相关的，充分必要条件是向量组中至少有一个向量，可由其余个向量线性表示.证明.假设)2(,,1n k x x k ≤≤ 是线性相关的，则存在一组不为零的a ，使011=++k k x a x a成立，我们不妨设0≠k a ，我们就可得到1-1,,k x x 之间是线性相关.即111--++-=k kk k k x a a x a a x 因此k x 可由其余向量线性表示. 这证明了必要性条件;充分性是显而易见的,因为正如我们之前所说的,每组包含一个线性相关的子集其本身就是线性相关.§7.基定义：在向量空间V 中，存在一组线性无关的集合x ，使得V 中的每个元素都可以用x 线性表示，则称集合x 为向量空间V 中的一个基.如果向量空间V 含有一个有限的基,则称V 是有限维的.除了偶尔考虑这些例子以外,在这本书中,我们主要将注意力集中于有限维向量空间.例如基，我们再次转向向量空间P 和n E .在向量空间P 中，集合}{n x 其中 2,1,0,)(n ==n t t x n ，是它的一个基;通过定义，每一个多项式是n x 的一个有限维的线性组合.此外P 有无限维的基，对给定的任意有限多项式，我们可以发现有比他们的维数高的多项式;后者多项式显然不是前者的线性组合.关于基础一个例子，在n E 中向量n i x i ,,1, =,i x 的第j 个坐标定义成ij δ (在这里我们第一次使用克罗内克积δ;它是由当j i =，ij δ=1和当j i ≠，ij δ=0定义的).因此,我们认为,向量)1,0,0(),0,1,0(),0,0,1(321===x x x 是3E 中的一组基.不难看出,它们是线性无关的,公式332211321),,(x x x x ξξξξξξ++==证明了在3E 中每一个x 是它们的一个线性组合.一般在有限维向量空间V 中，,基},,{n 1x x 中的每个x 可以写成如下形式：ii i x x ∑=ξ 我们断言，x 是由ξ唯一确定.这一说法的依据是线性相关理论中所使用到的论证.如果我们有ii i x x ∑=η，那么可以通过减法，可得 0)=-∑i ii i x ηξ（由于i x 是线性无关的，这意味着0-i i =ηξ其中n i ,,1 =，换言之，η和ξ是一样的.参考文献[1] N.Bourbaki, Algebre; Chap.Ⅱ（Algebre lineaire ）, Paris, 1947,and Chap. Ⅲ(Algebre mullilineaire), Paris, 1948.[2] B.L. Van Der Waerden, Modern algebra, New York, 1953.[3] S.Banch, Theorie des operations lineaires, Warszawa, 1932.[4] F.Riesz and B. Sz.-Nagy, Functional analysis, New York, 1955.[5] P.R.Halmos, Introduction to Hilbert space, New York, 1951.[6] M.H.Stone,Linear transformations in Hilbert space, New York, 1932.[7] R.Courant and D.Hilbert, Methods of mathematical phsics,New York,1953.[8] J.V on Neumann,Mathematical foundations of quantum mechanics,Princeton,1955.Finite-Dimensional Vector Spaces§2. Vector spacesWe come now to the basic concept of this book. For the definition that follows we assume that we are given a particular field F ; the scalars to be used are to be elements of F .Definition. A vector space is a set V of elements called vectors satisfying the follo-wing axioms.（A）To every pair , x and y，of vectors in ʋthere corresponds a vector x + y, called the sum of x and y , in such a way that(1) addition is commutative , x + y = y + x(2) addition is associative, x+(y+z)= (x+y)+z(3) there exists in V a unique vector 0 (called the origin) such that x+ 0 =xfor every vector x, and(4) to every vector x in V there corresponds a unique vector -x such thatx+(-x)=0（B）To every pair , α and x，where α is a scalar and x is a vector in V, there corresponds a vector αx in V, called the product of α and x，in sucha way that(1) multiplication by scalars is associative, α(βx)=(αβ) x, and(2) 1x=x for every vector x.（C）(1) Multiplication by scalars is distributive with respect to vector addition,α(x+y)= αx+αy, and(2) multiplication by vectors is distributive with respect to scalar addition, (α+β)x=αx+βxThese axioms are not claimed to be logically independent ; they are merely a co-nvenient characterization of the objects we wish to study . the relation between a vector spaces V and the underlying field F is usually described by saying that V is a vector space over F . if F is the field R of real numbers , V is called a real vector space ; similarly if F is Q or if F is E, we speak of rational vector spaces or com-plexvector space.§3. ExamplesBefore discussing the implications of the axioms，we give some examples. We shall refer to these examples over and over again，and we shall use the notation established here throughout the rest of our work.(1)Let 1E（=E）be the set of all complex numbers；if we interpret x+y and ax as ordinary complex numerical addition and multiplication.1E becomesa complex vector space.(2) Let p be the set of all polynomials , with complex coefficients, in a variable t. To make p into a complex vector space , We interpret vector addition and scal ar multiplication as the ordinary addition of two polynomials and the multiplication ofa polynomial by a complex number; the origin in p is the polynomial identically zero.Example (1) is too simple and example (2) is too complicated to be typical of the main contents of this book .we give now another example of complex vector spaces which ( as we shall see later ) is general enough for all our purposes.(3)Let n E ，n =1,2,…, be the set of all n -tuples of complex numbers. ifx =(n ξξ，，1) and y =(n ηη，， 1) are elements of n E ,we write ,by definition, x +y = (1ξ+1η,…, n ξ+n η),x α= (α1ξ,…, αn ξ),0 = (0,…,0),-x = (-1ξ,…,- n ξ).It is easy to verity that all parts of our axioms (A),(b).and(c), §2,are satisfied, so that n E is a complex vector space; it will be called n-adimensional comple x coordinate space.(4) For each positive integer n , let n p be the set of all polynomials (with comple x coefficients , as in example (2)) of degree ≤n -1, together with the polynomial id entically zero . (in the usual discussion of degree ,the degree of this polynomial is no t defined , so that We cannot say that it has degree ≤n -1. ) With the same interpreta tion of the linear operations (addition and scalar multiplication ) as in ( 2 ) , n p i s a complex vector space.(5) A close relative of n E is the set n R of all n-tuples of real numbers. W ith the same formal definitions of addition and scalar multiplication as for n E , ex cept that now we consider only real scalar α, the space n R is A real vector spa-ce; it will be called n-dimensional real coordinate space.(6) All the preceding examples can be generalized. Thus, for instance, an obviou s generalization of (1) can be described by saying that every field may be regarded as a vector space over itself. A common generalization of ( 3 ) and ( 5 ) atarts with a n arbitrary field F and forms the set F of n-tuples of elements of F ; the formal d efinitions of the Linear operations are the same as for the case F =E .(7) A field , by definition , has at least two elements ; A vector space however, may have only one . Since every vector space contains an origin, there is essentially (i.e , except for notation ) only one vector space having only one vector . This most trivial vector space will be denoted by θ.(8) If , in the set R of all real numbers, addition is defined as usual and multipli cation of a real number by a rational number is difined as usual, then R becomes a r ational vector space.(9) If, in the set E of all complex numbers, addition is defined as usual and mu ltiplication of a complex number by a real number is defined as usual, then E beco mes a real vector space. ( Compare this example with (1); they are quite different.)§4. CommentsA few comments are in order on our axioms and notation .There are striking simila rities ( and equally striking differences ) between the axioms for a field and the axio ms for a vector space over a field. in both cases, the axioms ( A ) describe the additiv e structure of the system , the axioms (B) describe Its multiplicative structure , and the axioms ( C ) describe the connection between the two structures, Those familiar with algebraic terminology will have recognized the axioms ( A ) (in both 1 and 2 ) as the defining conditions of an abelian ( commutative ) group; the axioms (B ) and (C ) (in §2 ) express the fact that the group admits scalars as operators. We mention in passing that if the scalars are elements of a ring ( instead of A field) , the general ized concept corresponding to a vector space is called A module.Special real vector spaces ( such as 2R and 3R ) are familiar in geometry. There seems at this stage to be no excuse for Our apparently uninteresting insistence on fiel ds other than R , and, in particular , on the fielde E of complex numbers .We hope that the reader is wulling to take it on faith that we shall have to make use of deep properties of complex numbers later ( conjugation , algebraic closure ) , and that in bo th the applications of vector spaces to modern (quantum mechanical ) physics and th e mathematical generalization of our results to Hilbert space complex numbers play an important role. Their one great disadvantage is the difficulty of drawing pictur es ; the ordinary picture ( Argand diagram ) of 1E is indistinguishable from that of 2R , and a graphic representation of 2E seems to be out of human reach. On the occ asions when we have to use pictoral language we shall therefore use the terminology of n R in n E , and speak of 2E, for example as a plane.Finally we comment on notation . We observe that the symbol 0 has been used in two meanings : Once as a scalar and once as a vector. To make the situation worse, we shall later, when we Introduce linear functionals and Linear transformations , give it still other meanings. Fortunately the relations among the various interpretatio ns of 0 are such that , after this word of waning , no confusion should arise fromthis practice.Exercises1.Prove that if x and y are vectors and if is a scalar，then the following relations hold.0),(00),(0),(=∙=-=+αc b xx a00),(=∙x d （observe that the same symbol is used on both sides of this equation ；on the left it denotes a scalar, on the right it denotes a vector.）(e) if αx =0，then either α=0 or x =0（or both ）(f) –x =(-1) x(g) y +(x -y )=x (Here x -y =x +（-y ）)2. if P is a prime, then n P Z is a vector space over P Z (cf. §1,ex.3); howmany vectors are there in this vector space?3. let V be the set of all (ordered) pairs or real numbers. If ),(21ξξ=x a ),(21ηη=y are elements of V , writex +y = ），（2211ηξηξ++αx = ），（01αξ 0 =（0,0）-x = ），（21--ξξ Is V a vector space with respect to these definitions of the linear operations?why?4. Sometimes a subset of a vector apace is itself a vector space (with respe ct to the linear operations already given). Consider, for example, the vector space 3E and the subsets V of 3E consisting of those vectors (321,,ξξξ) for which（a ）1ξ is real,（b ）1ξ=0,（c ）either 1ξ=0 or 2ξ=0,（d ）1ξ+2ξ=0（e ）1ξ+2ξ=1In which of these cases is V a vector space?5. Consider the vector space p and the subsets V of p consisting of those vectors (polynomials) x for which（a ）x has degree 3,（b ）2x （0）=x （1）,（c ）x （t ）≥0 whenever 0 ≤ t ≤ 1,（d ）x （t ）=x （1-t ）for all t .In which of these cases is V a vector space?§5. Linear dependenceNow that we have described the spaces we shall work with, we must specify the relations among the element of those spaces that will be of interest to us.We begin with a few words about the summation notation . if corresponding to each of a set of indices i there is gaven a vector i x , and if it is not necessary or n ot convenient to specify the set of indices exactly, we shall simply speak of a set {}i x of vectors . (we admit the possibility that the same vector corresponds to two di stinct Indices. in all honesty, therefore, it should be stated that what is important is not which vectors appear in {}i x , but how they appear. ) If the index-set under cons ideration is finite , we shall denote the sum of the corresponding vector by ∑i i x (or,when desirable , by a more explicit symbol such as ∑=n i i x 1) . In order to avoid freque nt and fussy case distinctions, it is a good Idea to admit Into the general theory sums s uch as ∑i i x even when there are no indices i to be summed over , Or , more precis ely , even when the index – setunder consideration is empty . ( in that case of cours e, there are no vectors to sum , or , more precisely , the set {}i x is also empty. ) The value of such an " empty sum " is defined , naturally enough, to be the vector 0.Definition. A finite set {}i x of vectors is linearly dependent if there exists a c orresponding set {}i a of scalars, not all zero,such that0=∑i i ix aIf, on the other hand, 0=∑i i i x a implies that i a = 0 for each i , the {}i x is l inearly independent.The wording of this definition is intended to cover the case of the empty set; th e result in that case , though passibly paradoxical, dovetails very satisfactorily with the rest of the theory. The result is that the empty set of vectors is linearly ind ependent . indeed, if there are no indices i , then it is not possible to pick out some of them and to assign to the selected ones a non-zero scalar so as to make a certain sum vanish. The trouble is not in avoiding the assignment of zero ; it is infinding an index to which something can be as assigned. Note that this argument shows that th e empty set is not linearly dependent ; for the reader not acquainted with arguig by“vacuous implication,” the equivalence of the definition of linear independence wit h the straightforward negation of the definition of linear dependence needs a little additional intuitive justification. The easiest way to feel comfortable about the assertion “0=∑ii i x a implies That i a =0 for each i ,” in case there are no ind ices i , is to rephrase it this Way:”if 0=∑i i i x a , then there is no index i forwhich i a ≠0.” This version is obviously true if there is no index i at allLinear dependence and Independence are properties of sets of vectors; it is custo mary, however , to apply the adjectives to vectors themselves, and thus we shall som etimes say " a set of linearly independent vectors” instead of “a linearly independe nt set of vectors.” it will be convenient also to speak of the linear dependence and i ndependence of a not necessarily finite set , x , of vectors. We shall say that x is line arly independent if every finite subset of x is such; otherwise x is linearly depende nt.To gain insight into the meaning of linear dependence , let us study the examples o f vector spaces that we already have.(1) If x and y are any two vectors in 1E , then x and y form a linearly dependent set. If x =y =0, this is trivial; if not, then we have, for example, th e relation y x +(-x )y =0. Since it is clear that every set containing a linearly dependent subset is itself linearly dependent, this shows that in 1E erery set c ontaining more than one element is a linearly dependent set.(2) More interesting is the situation in the space P the vectors y x ,, and z defined by,1)(),1()(,1)(2t t z t t t y t t x -=-=-=are, for example,linearly deendent, since x +y -z =0. However, the infinite set o f vectors ,,,,210 x x x ,defined by,,)(,)(,1)(2210 t t x t t x t x ===is a linearly independent set, for if we hadany relation of the form01100=+++n n x a x a x athen we should have a polynomial identity010=+++n n t a t a aWhence 010=+==n a a a(3) As we mentioned before , the spaces n E are the prototype of what we want to study ; let us examine, for example , the case n =3. To those familiar with higher -dimensional geometry , the notion of linear dependence in this space ( or , more properly speaking , in its real analogue 3R ) has a concrete geometric meaning, which w e shall only mention, In geometrical language, two vectors are linearly dependent i f and only if they are on collinear with the origin .(If one thinks of a vector not as a point in a space but as an arrow pointing from the origin to some given poi nt, the preceding sentence should be modified by crossing out the phrase “With the or igin " both times that it occurs. ) We shall presently Introduce the notion of linear manifolds (or vector subspaces) in a vector space, and, in that connection , we s hall occasionally use the language suggested by such geometrical considerations.§6.Linear combinationsWe shall say, whenever ii i x a x ∑=, that x is a linear combination of {}i x ;we shall use without any further explanation all the simple grammatical implic ations of this terminology. Thus we shall say, in case x is a linear combinatio n of {}i x , that x is linearly independent on {}i x ; we shall leave to the reade r the proof that if {}i x is linearly independent, then a necessary and sufficient condition that x be a linear combination of {}i x is that the enlarged set, obta ined by adjoining x to {}i x , be linearly dependent. Note that, in accordance with the definition of an empty sum, the origin is a linear combination of the emptyset of vectors; it is, mareover, the only vector with this property.The following theorem is the fundamental result concerning linear dependenc e.Theorem. The set of non-zero vectors n x x ,,1 is linearly dependent if an d only if some n k x k ≤≤2,, is a linear combination of the preceding ones. Proof. Let us suppose that the vectors n x x ,,1 are linearly dependent, an d let k be the first integer between 2 and n for which k x x ,,1 are linea rly dependent. (If worse comes to worst, our assumption assures us that n k =will do.) Then011=++k k x a x afor a suitable set of a’s (not all zero); moreover, whatever the a’s, we cannot have 0=k a , for then we should have a linear dependence relation among 11,,-k x x contrary to the definition of k . Hence111--++-=k kk k k x a a x a a x as was to be proved. This proves the necessity of our condition; sufficiency is clear since, as we remarked before, every set containing a linearly dependent s et is itself such.§7. BasesDefinition. A (linear) basis (or a coordinate system) in a vector space V is a set x of linearly independent vectors such that every vector in V is a linear combination of elements of x . a vector space V is finitedimensional if it has a finite basis.Except for the occasional consideration of examples we shall restrict our atte ntion, throughout this book, to finite-dimensional vector spaces.For example of bases we turn again to the spaces P and n E . in P , the se t }{n x , Where 2,1,0,)(n ==n t t x n , is a basis; every polynomial is, by definit ion, a linear combination of a finite number of n x . Moreover P has no finite basis, for, given any finite set of polynomials, we can find a polynomial of h igher degree than any of them; this latter polynomial is obviously not a linear combination of the former ones.An example of a basis in n E is the set of vectors n i x i ,,1, =, defined by the condition that the j -th coordinate of i x is ij δ. (Here we use for the first time the popular kronecker δ; it is defined by ij δ=1 if j i = and ij δ=0 if j i ≠.) Thus we assert that in 3E the vectors )0,1,0(),0,0,1(21==x x and )1,0,0(3=x form a basis. It is easy to see that they are linearly independent; t he formula332211321),,(x x x x ξξξξξξ++==proves that every x in 3E is a linear combination of them.In a general finite-dimendional vector space V , with basis },,{n 1x x , we know thatevery x can be written in the formii i x x ∑=ξ we assert that the s 'ξ are uniquely determined by x . The proof of this asserti on is an argument often used in the theory of linear dependence. If we had ii i x x ∑=η, then we should have, by subtraction, 0)=-∑i i i i x ηξ（Since the i x are linearly independent, this implies that 0-i i =ηξ for n i ,,1 =; in other words, the s 'ξ are the same as the s 'η.RECOMMENDED READING[1] N.Bourbaki, Algebre; Chap.Ⅱ（Algebre lineaire ）, Paris, 1947,and Chap. Ⅲ(Algebre mullilineaire), Paris, 1948.[2] B.L. Van Der Waerden, Modern algebra, New York, 1953.[3] S.Banch, Theorie des operations lineaires, Warszawa, 1932.[4] F.Riesz and B. Sz.-Nagy, Functional analysis, New York, 1955.[5] P.R.Halmos, Introduction to Hilbert space, New York, 1951.[6] M.H.Stone,Linear transformations in Hilbert space, New York, 1932.[7] R.Courant and D.Hilbert, Methods of mathematical phsics,New York,1953.[8] J.V on Neumann,Mathematical foundations of quantum mechanics,Princeton,1955.。