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英文文献翻译
外文文献原稿和译文原稿Sodium Polyacrylate:Also known as super-absorbent or “SAP”(super absorbent polymer), Kimberly Clark used to call it SAM (super absorbent material). It is typically used in fine granular form (like table salt). It helps improve capacity for better retention in a disposable diaper, allowing the product to be thinner with improved performance and less usage of pine fluff pulp. The molecular structure of the polyacrylate has sodium carboxylate groups hanging off the main chain. When it comes in contact with water, the sodium detaches itself, leaving only carboxylions. Being negatively charged, these ions repel one another so that the polymer also has cross-links, which effectively leads to a three-dimensional structure. It has hige molecular weight of more than a million; thus, instead of getting dissolved, it solidifies into a gel. The Hydrogen in the water (H-O-H) is trapped by the acrylate due to the atomic bonds associated with the polarity forces between the atoms. Electrolytes in the liquid, such as salt minerals (urine contains 0.9% of minerals), reduce polarity, thereby affecting superabsorbent properties, especially with regard to the superabsorbent capacity for liquid retention. This is the main reason why diapers containing SAP should never be tested with plain water. Linear molecular configurations have less total capacity than non-linear molecules but, on the other hand, retention of liquid in a linear molecule is higher than in a non-linear molecule, due to improved polarity. For a list of SAP suppliers, please use this link: SAP, the superabsorbent can be designed to absorb higher amounts of liquids (with less retention) or very high retentions (but lower capacity). In addition, a surface cross linker can be added to the superabsorbent particle to help it move liquids while it is saturated. This helps avoid formation of "gel blocks", the phenomenon that describes the impossibility of moving liquids once a SAP particle gets saturated.History of Super Absorbent Polymer ChemistryUn til the 1980’s, water absorbing materials were cellulosic or fiber-based products. Choices were tissue paper, cotton, sponge, and fluff pulp. The water retention capacity of these types of materials is only 20 times their weight – at most.In the early 1960s, the United States Department of Agriculture (USDA) was conducting work on materials to improve water conservation in soils. They developed a resin based on the grafting of acrylonitrile polymer onto the backbone of starch molecules (i.e. starch-grafting). The hydrolyzed product of the hydrolysis of this starch-acrylonitrile co-polymer gave water absorption greater than 400 times its weight. Also, the gel did not release liquid water the way that fiber-based absorbents do.The polymer came to be known as “Super Slurper”.The USDA gave the technical know how several USA companies for further development of the basic technology. A wide range of grating combinations were attempted including work with acrylic acid, acrylamide and polyvinyl alcohol (PVA).Since Japanese companies were excluded by the USDA, they started independent research using starch, carboxy methyl cellulose (CMC), acrylic acid, polyvinyl alcohol (PVA) and isobutylene maleic anhydride (IMA).Early global participants in the development of super absorbent chemistry included Dow Chemical, Hercules, General Mills Chemical, DuPont, National Starch & Chemical, Enka (Akzo), Sanyo Chemical, Sumitomo Chemical, Kao, Nihon Starch and Japan Exlan.In the early 1970s, super absorbent polymer was used commercially for the first time –not for soil amendment applications as originally intended –but for disposable hygienic products. The first product markets were feminine sanitary napkins and adult incontinence products.In 1978, Park Davis (d.b.a. Professional Medical Products) used super absorbent polymers in sanitary napkins.Super absorbent polymer was first used in Europe in a baby diaper in 1982 when Schickendanz and Beghin-Say added the material to the absorbent core. Shortly thereafter, UniCharm introduced super absorbent baby diapers in Japan while Proctor & Gamble and Kimberly-Clark in the USA began to use the material.The development of super absorbent technology and performance has been largely led by demands in the disposable hygiene segment. Strides in absorption performance have allowed the development of the ultra-thin baby diaper which uses a fraction of the materials – particularly fluff pulp – which earlier disposable diapers consumed.Over the years, technology has progressed so that there is little if any starch-grafted super absorbent polymer used in disposable hygienic products. These super absorbents typically are cross-linked acrylic homo-polymers (usually Sodium neutralized).Super absorbents used in soil amendments applications tend to be cross-linked acrylic-acrylamide co-polymers (usually Potassium neutralized).Besides granular super absorbent polymers, ARCO Chemical developed a super absorbent fiber technology in the early 1990s. This technology was eventually sold to Camelot Absorbents. There are super absorbent fibers commercially available today. While significantly more expensive than the granular polymers, the super absorbent fibers offer technical advantages in certain niche markets including cable wrap, medical devices and food packaging.Sodium polyacrylate, also known as waterlock, is a polymer with the chemical formula [-CH2-CH(COONa)-]n widely used in consumer products. It has the ability to absorb as much as 200 to 300 times its mass in water. Acrylate polymers generally are considered to possess an anionic charge. While sodium neutralized polyacrylates are the most common form used in industry, there are also other salts available including potassium, lithium and ammonium.ApplicationsAcrylates and acrylic chemistry have a wide variety of industrial uses that include: ∙Sequestering agents in detergents. (By binding hard water elements such as calcium and magnesium, the surfactants in detergents work more efficiently.) ∙Thickening agents∙Coatings∙Fake snowSuper absorbent polymers. These cross-linked acrylic polymers are referred to as "Super Absorbents" and "Water Crystals", and are used in baby diapers. Copolymerversions are used in agriculture and other specialty absorbent applications. The origins of super absorbent polymer chemistry trace back to the early 1960s when the U.S. Department of Agriculture developed the first super absorbent polymer materials. This chemical is featured in the Maximum Absorbency Garment used by NASA.译文聚丙烯酸钠聚丙烯酸钠,又可以称为超级吸收剂或者又叫高吸水性树脂,凯博利克拉克教授曾经称它为SAM即:超级吸收性物质。
北斗定位-毕业论文外文文献翻译
外文文献原稿和译文原稿Beidou positioningPrefaceNavigation satellite systems can provide all time, all weather and high accuracy positioning, navigation and timing services to users on the earth surface or in the near-earth space. It is an important space inf rastructure, which extends people’s range of activities and promotes social development. Satellite navigation is bringing up revolutionary changes to the world politics, economy, military, technology and culture.With a long history and a splendid culture, China is one of the important cradles of early human civilization. In ancient times, Chinese people used the Big Dipper (Beidou) for identifying directions, and invented the world’s first navigation device, the ancient compass (Sinan), which was a great contribution to the development of world civilization. In modern society, the Chinese-built BeiDou(COMPASS) system will become another contribution to the mankind.In early 1980s, China began to actively study the navigation satellite systems in line with C hina’s conditions. In 2000, BeiDou Navigation Demonstration System is basically established, which made China the third nation in possession of an independent navigation satellite system following the United States and Russia. At present, China is steadily accelerating the construction of the BeiDou Navigation Satellite System, and has already successfully launched 10 satellites so far.The BeiDou system will meet the demands of China’s national security, economic development, technological advances and social progress, safeguard national interests and enhance the comprehensive national strength. The BeiDou system will commit to providing stable, reliable and quality satellite navigation services for global users. Along with other GNSS providers, the BeiDou system will jointly promote the development of satellitenavigation industry, make contributions to human civilization and social development, serve the world and benefit the mankind.I. System DescriptionThe BeiDou system is comprised of three major components: space constellation, ground control segment and user terminals. The space constellation consists of five GEO satellites and 30 non-GEO satellites. The GEO satellites are positioned at 58.75°E, 80°E, 110.5°E, 140°E and 160°E respectively. The non-GEO satellites include 27 MEO satellites and three IGSO satellites. The MEO satellites are operating in an orbit with an altitudeof 21,500 km and an inclination of 55°, which are evenly distributed in three orbital planes. The IGSO satellites are operating in an orbit with an altitude of 36,000 km and an inclination of 55°, which are evenly distributed in three inclined geo-synchronous orbital planes. The subsatellite track for the three IGSO satellites are coincided while the longitude of the intersection point is at 118°E, with a phase difference of 120°.Ground control segment consists of several Master Control Stations (MCS), Upload Stations (US) and a network of globally distributed Monitor Stations (MS). The main tasks of MCS are to collect observing data from each MS, to process data, to generate satellite navigation messages, wide area differential data and integrity information, to perform mission planning and scheduling, and to conduct system operation and control. The main tasks of Upload Stations include completing the upload of satellite navigation messages, wide area differential data and integrity information, controlling and managing the payload. The tasks of Monitor Stations include continuous tracking and monitoring of navigation satellites, receiving navigation signals, sending observational data to the Master Control Station for the satellites orbit determination and time synchronization.The user terminals include various BeiDou user terminals, and terminals compatible with other navigation satellite systems, to meet different application requirements from different fields and industries.The time reference for the BeiDou Navigation Satellite System uses BeiDou Time (BDT). BDT’s length of second is a SI second. BDT was zero at 0:00:00 on Janu ary 1, 2006 Coordinated Universal Time (UTC). BDT is a continuous system, traceable to the UTC time maintained by the National Time Service Center (NTSC) of ChineseAcademy ofSciences, which is referred to as UTC (NTSC). The leap seconds with UTC information is broadcasted in the navigation messages. The difference between BDT and UTC maintains within 100ns.The coordinate framework of BeiDou system adopts China Geodetic Coordinate System 2000 (CGCS2000).Upon the full system completion, the BeiDou Navigation Satellite System can provide positioning, navigation and timing services to worldwide users. It can also provide wide area differential services with the accuracy of 1m and short messages services with the capacity of 120 Chinese characters each time.·Main functions: positioning, velocity measurement, one-way and two-way timing, short messages·Service area: global·Positioning accuracy: better than 10m·Velocity accuracy: better than 0.2m/s·Timing accuracy: 20nsII. System DevelopmentThe BeiDou system has followed the development concept of starting with regional services first and expanding to global services later. A three-step development strategy has been taken, with specifics as follows:Phase I: BeiDou Navigation Satellite Demonstration System. In 1994, Chinastarted the construction of BeiDou Navigation Satellite Demonstration System. In 2000, two BeiDou navigation experiment satellites were launched, and the BeiDou Navigation Satellite Demonstration System was basically established. In 2003, the third BeiDou navigation experiment satellite was launched, further enhancing the performance of the BeiDou Navigation Satellite Demonstration System.BeiDou Navigation Satellite Demonstration System consists of three major components: space constellation, ground control segment and user terminals. The space constellation includes three geostationary orbit (GEO) satellites, positioned at longitude of 80 degrees East, 110.5 degrees East and 140 degrees East respectively above the equator. Ground control segment consists of the ground control center and a number of calibrationstations. The ground control center is to complete satellite orbit determination, ionospheric correction, user location determination and user short message information exchange and processing. The calibration ground control stations are mainly to provide the distance measurement and correction parameters to the ground control center.The user terminals include the hand-held type, vehicle type, command type and other types of terminals, capable of position service application, location coordinates information receiving and other functions.The main functions and performance specifications of the BeiDou Navigation Satellite Demonstration System are as follows:·Main functions: positioning, one-way and two-way timing, short message communications;·Service Area: China and the surrounding areas;·Positioning Accuracy: better than 20 meters;·Timing Accuracy: 100 ns one-way, two-way 20 ns;·Short message communications: 120 Chinese characters per time.Phase II: BeiDou Navigation Satellite (regional) System. In 2004, Chinastarted construction of BeiDou Navigation Satellite System. In 2007, the first satellite, a round medium earth orbit satellite (COMPASS-M1) was launched. By 2012, the BeiDou system will consist of 14 satellites, including five GEO satellites, five IGSO satellites (two in-orbit spares), and four MEO satellites.The functions and performance parameters of BeiDou Navigation Satellite (regional) System are as follows:·Main functions: positioning, velocity measurement, one-way and two-way timing, short message communications;·Service Area: China and part of Asia- Pacific region ;·Positioning Accuracy: better than 10 meters;·Velocity Accuracy: better than 0.2 m/s;·Timing Accuracy: 50 ns;·Short message communications: 120 Chinese characters per message.Phase III: BeiDou Navigation Satellite System will completely be established by 2020.III. System ApplicationsSince it was officially brought into service in 2003, the BeiDou Navigation Satellite Demonstration System has been widely used in transportation, marine fisheries, hydrological monitoring, weather forecasting, forest fire prevention, timing for communication systems, power distribution, disaster mitigation, national security, and many other fields, which has been resulting in significant social and economic benefits. Particularly, the system has played an important role in the South China frozen disaster, earthquake relief in Wenchuan, SichuanProvince and Yushu, Qinghai Province, the Beijing Olympic Games, and the Shanghai World Expo.—In the field of transportation, built on the Beidou Navigation Satellite Demonstration System, applications such as Xinjiang Satellite Navigation Monitoring System of Public Transport, the Highway Infrastructure Safety Monitoring System, and the Port Scheduling High-precision Real-time Position Monitoring System, have promoted the BeiDou system and achieved a good demonstration effect.—In marine fisheries, built on the BeiDou Navigation Satellite Demonstration System, the marine fisheries integrated information service platform has provided vessel position monitoring, emergency rescue, information distribution, fishing boats in and out of port management and other services to the fishery administration departments.—The hydrological monitoring system, based on the BeiDou Navigation Satellite Demonstration System, has realized the real-time transmission of hydrological forecast information in mountainous regions, which has improved the accuracy o f the disaster forecasting and has helped the planning and scheduling programs for the flood and drought control.—In the field of weather forecasting, a series of BeiDou terminal equipment have been developed for weather forecast, and various practical and feasible system solutions have been worked out to address the automatic data transmission issues for the China Meteorological Administration and a number of local weather centers and stations.—In the field of forest fire prevention, the BeiDou Navigation Satellite Demonstration System has been successfully used in forest fire prevention system. Its positioning and short message communication services have achieved good results.—In the field of time synchronization for communication systems, the successful implementation of BeiDou two-way timing demonstration program has achieved breakthroughs in some key technical areas such as long distant fiber technology, and an integrated satellite-based timing system has been developed.—In the field of power distribution, built on the BeiDou Navigation Satellite Demonstration System, the successful implementation of power system time synchronization demonstration program has created basis for the high precision applications such as the electric accident analysis, the electricity early warning and protection systems.—In the field of disaster mitigation, the navigation, positioning, short message communications and position reporting capabilities of the BeiDou Navigation Satellite Demonstration System have provided services for the nationwide real-time disaster relief commanding and dispatching, emergency communications, rapid reporting and sharing of disaster information, which has significantly improved the rapid response of the disaster emergency relief and decision-making capability.Upon the full completion, the BeiDou Navigation Satellite System will provide more high-performance positioning, navigation, timing and short-message communication services for civil aviation, shipping, railways, finance, postal and other industries.IV. International Exchange and CooperationThe international exchange and cooperation for the BeiDou Navigation Satellite System will be carried out in an active and pragmatic way, which is in line withChina’s foreign policies, focusing on China's basic tasks and strategic objectives for the construction of navigation satellite systems, using the domestic and international markets and resources in a coordinated way. The international exchange and cooperation will be proceeded in a phased, focus-centered, non-discriminatory and selective approach in accordance with the overall development plan of China's navigation satellite system. It will be built upon the basis of equality, mutual benefit, mutual complementarity, peaceful utilization and mutual development and the generally accepted principles of the international laws.The BeiDou Navigation Satellite System adheres to the open and friendly attitude, and has already carried out extensive exchanges and consultation with the countries that have navigation satellite systems, to promote navigation satellite system compatibility and interoperability globally. Through the exchange and cooperation with countries that do not have a navigation satellite system, we also support their use of the existing resources globally and share the benefits of the satellite navigation development.China's international exchange and cooperation in the field of satellite navigation started in the 1990s. In nearly 20 years, various forms of activities have been carried out with extensive results.In 1994, under the framework of International Telecommunication Union(ITU),China started the BeiDou Navigation Satellite System frequency coordination activities. Satellite network information was submitted in accordance with the BeiDou system construction plan and progress. International frequency coordination has been carried out in a phased, step by step, focus-centered approach. China has actively participated bilateral frequency coordination activities with Europe, the UnitedStates and Russia, and has actively taken part in the World Radiocommunication Conference and the meetings of ITU study groups and working groups.China, as an important member of the International Committee on Global Navigation Satellite Systems (ICG), has participated in every ICG General Assembly Meeting and the ICG Providers Forum. In 2007, China became one of the four core providers designated by the organization. Focusing on compatibility and interoperability, China has carried out the extensive exchange and cooperation with the other navigation satellite systems in the world. The Technical Working Group (TWG) on compatibility and interoperability between BeiDou and Galileo was established. Until now, seven TWG meetings have been held.China actively participates, organizes and hosts international academic exchanges on satellite navigation, which include the American Institute of Navigation (ION) Conferences, the International Symposium on GPS/GNSS (ISGNSS), Munich Satellite Navigation Summit and other international conferences and forums. The China academic conferenceon satellite navigation is held annually, together with many other forums and seminars.China encourages and supports domestic research institutions, industrial enterprises, universities and social organizations, under the guidance of the government policy, to carry out international exchanges, coordination and cooperation activities with other countries and international organizations in the fields of the compatibility and interoperability, satellite navigation standards, coordinates frame, time reference, application development and scientific research. China has been actively engaged in international activities in terms of monitoring and assessment of open service for GNSS to promote the BeiDou Navigation Satellite System better serving the global users, and to promote the development of satellite navigation technology.ConclusionThe rapid development of the BeiDou Navigation Satellite System is attributedto China's reform and opening-up policy as well as the sustainable development of economy. As always, China will continue to promote the Global Navigation Satellite System construction and industrial development, to encourage the use of new satellite navigation technologies to provide new services, meeting the growing diversified needs of the people. By actively propelling international exchanges and cooperation, China will realize the compatibility and interoperability between the BeiDou Navigation Satellite System and other navigation satellite systems in the world. China will provide global customers with high performance and highly reliable positioning, navigation and timing services.The Launch Record of BeiDouNavigation Satellites·October 31, 2000, launch of 1st BeiDou navigation experiment satellite.·December 21, 2000, launch of 2nd BeiDou navigation experiment satellite.·May 25, 2003, launch of the 3rd BeiDou navigation experiment satellite.·February 3, 2007, launch of the 4th BeiDou navigation experiment satellite.·April 14, 2007, launch of the 1st BeiDou navigation satellite.·April 15, 2009, launch of the 2nd Beidou navigation satellite.·January 17, 2010, launch of the 3rd BeiDou navigation satellite.·June 2, 2010, launch of the 4th BeiDou navigation satellite.·August 1, 2010, launch of the 5th BeiDou navigation satellite.·November 1, 2010, launch of the 6th BeiDou navigation satellite. ·December 18, 2010, launch of the 7th BeiDou navigation satellite. ·April 10, 2011, launch of the 8th BeiDou navigation satellite. ·July 27, 2011, launch of the 9th BeiDou navigation satellite. ·December 2, 2011, launch of the 10th BeiDou navigation satellite.译文北斗定位前言卫星导航系统可以提供所有的时间,所有天气情况下用户在地球表面或近地空间的高精度定位、导航和授时服务。
文献译文模板
院系:经济与管理学院专业班级:营销0702 学生姓名:路妍指导教师:杨淑霞学号:1071340217 译文成绩:≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈华北电力大学毕业设计(论文)译文部分原文著作(期刊)名称:Supply chain design and analysis: Models and methods作者:Benita M Beamon原文出版单位:International Journal Production Economics原文出版时间:15 April 1998原文出版地点:Int. J. Production Economics 55 (1998) 281Ð294供应链的设计与分析:模型和方法摘要:多年来,研究人员和从业人员主要单独调查供应链的各个工序,然而,近年的研究重点放在了供应链的绩效、设计和分析上。
这种改变很大程度上是由于制造成本上升、生产资源萎缩、产品生命周期缩短、制造业内竞争加剧和全球市场经济化所引起的。
本文的主要目的是:(1)提供多级供应链建模的文献综述;(2)定义这一领域未来的研究议程。
关键词:供应链,生产,分销,物流1、介绍供应链被定义为一个完整的过程,在这过程中,有一系列多元化的商业实体(例如供应商、制造商、分销商、零售商)统一协调。
整个过程包括:(1)获取原材料;(2)将原材料生产为指定产品;(3)将产品交付给零售商。
传统意义的供应链的特点是原材料顺向流动,而信息逆向反馈。
近年来,研究者和实践者首先单独地调查了整条供应链上的各个过程。
现在我们应把注意力转移,把供应链作为一个整体考虑,进而评价绩效、研究如何设计、分析整体供应链。
从实际角度研究,供应链的概念源于生产环境的一系列变化,包括生产成本的提高、生产资料的短缺、产品寿命周期的变短、生产领域竞争水平的提高和经济全球化等因素的影响。
2、供应链的概念正如上文所提,供应链是一个完整的过程,包括将原材料转变为最终产品,将产品供应给顾客的整个过程。
外文文献原稿和译文
外文文献原稿和译文原稿MechanicalandRegenerativeBrakingIntegrationforaHybridElectricVehicleAbstract,namelyanelectricmotorandinternalcombustionengine,whichallowtheelimina tionofidling,,theaddedcostofthehybridelectricsystemhashinderedthesalesofth esevehicles.JapanNorth America automotive companieshavedevelopedandreleasedforsaletheirownhybridelectric unpredictablegasprices,thesalesofhybridelectricvehicleshaveincreaseddramat ically inrecentyears.2.1.1HybridConfigurationsForthepast100yearstheobjectiveofthehybridhasbeentoextendtherangeofelec tricvehiclesandtoovercometheproblemoflongrechargingtimes35.Therearethree ,par allelhybridsandseries/parallelhybrids.Eachconfigurationhasitsadvantagesanddisadvantageswhichwillbediscussedi nthefollowingsections.SeriesHybridsInserieshybridsthemechanicaloutputfromtheinternalcombustionengineisuse dto driveageneratorwhichproduceselectricalpowerthatcanbestoredinthebatteriesor highpowersystemssuchaslargetrucksorlocomotivesbutcanalsobeusedforlowerpowe rpassengervehicles18.2.1.2‘degreeofhybridization’toquantifytheelectrica lpowerpotentialofthesevehicles.ThedegreeofhybridizationrangesfromDOH=0foraconventionalvehicletoDOH=1f oranallelectricvehicle25.Asthedegreeofhybridizationincreases,asmallerICEcanbeusedandoperatedclosertoitsoptimumefficiencyforagreaterproportionoftheti me,.MicroHybrid MicrohybridshavethesmallestdegreeofhybridizationandusuallyconsistofanintegratedstartergeneratorISG2.1.31500 kg100 km/h0 km/h0 km/h50 km/h2.1.42.1.5译文混合动力电动汽车机械和再生制动的整合摘要为了减少对环境的污染和车辆的燃油消耗,混合动力电动汽车已经成为汽车工业的首选方法;混合动力电动汽车通过使用由电动马达和内燃发动机组成的混合动力系统来达到减少环境污染和燃油消耗的目的;混合动力系统消除了怠速,使发动机以一种更有效的方式运行,增加了再生制动的使用;但是,混合动力的成本的增加阻碍了这些车辆的销售;在这里提出一个更具成本效益的电液制动系统的设计;该系统使用电控机械结合的控制方式控制制动助力器产生的推动力,并有足够的时间反应;这个系统使驾驶员清楚地了解机械和再生制动力矩的混合,使再生制动力系统得到有效的控制;一个系统化的设计过程是其次,重点在于展示概念设计方案的可行性和使用虚拟和实物模型的初步设计功用;虚拟和实物模型的结合使用成为验证和开发系统的强大工具,本文将介绍和讨论在设计过程中模型所起到的作用;因为在设计过程中设计者可以获得相关的经验,提倡学生设计实物模型,以提高学生的学习经验;很明显,这正是本文所要提出的;现代混合动力电动汽车随着油价的上涨和环境保护意识的提高,消费者和政府迫使汽车行业开始生产省油和对环境污染小的汽车;一个有前景的方法就是现在实行的混合动力电动汽车;混合动力汽车指的是有两个或两个以上动力来源的车辆;混合动力汽车动力的来源可能有很多的不同,但是现在混合动力汽车最常见的布局是由内燃发动机和电动马达,能量储存系统共同输出动力,这样的车辆就叫混合动力电动汽车;汽车可以同时使用发动机和电动马达输出的动力,从而可以提高汽车的使用性能和效率,进而又可以提高燃油经济性,减少废气的排放,同时还能满足消费者对汽车性能的要求;1997年,丰田成普瑞斯为了第一款混合动力电动汽车,在日本进行了批量生产;本田公司花费了三年的时间进行混合动力电动车的生产,然后进军北美市场;丰田普瑞斯在北美发行几个月后,本田Insight紧随其后也在北美进行发行;混合动力电动车具有再生制动系统的独特优势;在制动过程,通常用于动力输出的电动马达,可以起到发电机的功用,把汽车的动能转化为蓄电池的电能,而不会转化为热能浪费掉;转换的电能可以储存到蓄电池中,然后可以作为电动马达驱动汽车使用的能量;考虑到蓄电池能量密度时,动能转换为电能这个过程就更加重要了;能量密度是指单位体积或质量下能量储存系统所储存的能量;为了说明这一点,我们可以做个对比,4.5公升的汽油通常可以维持一辆汽车行驶50千米;而要把相同的能量储存到蓄电池中,则需要一个质量约为270千克的铅酸蓄电池;这就说明了在汽车行驶过程中能够有效地储存再生制动系统产生的能量的重要性,从而可以保证在提高混合动力电能车性能的前提下,不至使能量储存系统所占体积过大;再生制动系统研究范围本文所提出的再生系统的研究范围是研究再生制动系统和机械制动系统之间相互作用的关系,目的是设计开发出一个低成本的再生制动系统,从而可以应用到未来经济型的混合动力电动汽车上;这个系统可以根据驾驶员的需要进而控制再生制动系统和机械制动系统产生的制动力矩的结合,还应该保证这个过程的平顺性和安全性;再生制动力矩是通过使用的异步电动机的矢量控制算法进行控制的;但是,独立地控制制动踏板产生的机械制动力矩,同时又要保持机械制动系在再生制动系统失效后起到备用作用,这是一个很大的难题;为了解决这个问题,需要研究一个通过减少制动主缸内制动液压来来控制机械制动系统产生的制动力矩的制动系统;混合电动汽车概述混合动力电动车已经成为了可以在短时间内减少汽车污染排放和提高燃油经济型的解决方法之一;在过去的10年几乎所有的主要汽车公司都已经向公众发行销售自己的混合动力电动汽车,混合动力电动汽车的普及和销售在这个世纪有了很明显的增长,随着不可预测的汽油价格的增长和对环境保护的关注,混合动力电动汽车的销售将在最近几年内急剧增长;2.1.1混合动力装置在过去100年来混合动力的研究目标是延长电动汽车的使用寿命,解决蓄电池的长期充电问题;在目前市场,现在主要有三种混合动力装置,这些混合动力装置为串联混合动力,并联混合动力,串并联混合动力;每一种动力装置都有其优点和缺点,这将在以后的章节进行讨论;串联混合动力串联混合动力汽车使用发动机输出的动力来驱动发电机产生电能,这些电能可以储存在蓄电池中,也可以用来驱动电动马达来驱动汽车;在串联混合动力汽车上,发动机和驱动轮之间没有直接的机械连接,串联混合动力往往在高功率系统中使用,如大型货车或火车,也可以应用到低功率的客运车辆上;发动机输出的机械能和蓄电池输出的电能可以通过电子控制器进行控制接合,然后这个电子控制器通过比较驾驶员所需的动力和汽车车速,电动马达输出的转矩,从而决定每个动力源驱动汽车行驶所要输出的能量;在制动过程中,这个电子控制装置可以使电能输出模式转换为再生模式,直接把再生制动系统产生的电能储存在蓄电池内;按照这种布置方式进行设计有很多的优点;发动机可以保持高效率的运行,使发动机产生的电能在蓄电池和驱动马达之间得到分配;发动机在其最高效率的工况下运行,排放可以大大降低,燃烧每体积的燃料可以产生更多的电能;因为串联动力装置结构简单且成本低,这种动力装置很容在汽车上落实;并联混合动力在并联混合动力汽车中,发动机输出的机械功传到变速箱中;发动机输出的机械功和电动马达输出的功在变速箱内进行机械式的接合,混合的机械功用于驱动汽车行驶;在这种混合动力装置结构中,发动机和驱动轮之间有直接的机械连接;在串联混合动力装置中,电子控制器通过比较驾驶员所需的动力和汽车车速,电动马达输出的转矩,从而决定每个动力源驱动汽车行驶所要输出的能量,以满足汽车行驶性能,获得最佳的效率;正如串联混合装置一样,并联混合动力也以相似的方法控制再生制动;并联混合动力装置通常应用到低功率的电动车中,这两种驱动力可以同时使用,提供更高的行驶性能;与串联混合动力系统相比,并联混合动力系统有很多优势;其中最重要的一项优势是效率高,因为在并联混合动力中,电能和机械能只需转换一次,而在串联混合动力中,电能和机械能需要两次转换;由于并联混合动力可以使发动机和电动马大产生的动力同时结合起来,在不损失汽车行驶性能的前提下,可以使用体积小的电动马达,同时也降低了油耗和排放;最后,并联混合动力汽车在行驶过程中只需使发动机运行,而不需要另一个发电机为蓄电池充电;串、并联混合动力串并联混合动力装置结合了串联和并联动力装置的特点;这种混合方式汽车通过使用动力分配装置来控制双动力源电动马达输出动力,发动机输出动力或者两者同时输出驱动汽车行驶;虽然这种装置形式可以获得串联混合动力装置和并联混合动力装置的优点,因为考虑到汽车实际行驶可能性,这种装置的控制算法会变得非常复杂; 2.1.2混合度现在道路上行驶的混合动力电动汽车大多是串联混合动力,并联混合动力,或者串并联混合动力,因此定义一个‘混合度’变量来评价混合动力电动汽车的电能潜能是非常有意义的;混合度变从传统车辆DOH=0到所有电动车DOH=1之间变化,随着混合度的增加,在汽车上可以使用一个比较小的发动机,同时发动机可以在最接近最佳效率的工况下运行很长的时间,这样就可以减少燃油的消耗和废气的排放;电动马达输出的功用P表emP表示;示,发动机输出的功用ice微混合动力微混合指的是最小混合度,通常是由一个连接到发动机曲轴的综合起动发电机组成;在加速和怠速过程中,综合起动发电机使发动机处于关闭状态,从而节约燃油;加速时,在燃油喷入汽缸之前,综合起动发电机使发动机的曲轴加速旋转;在加速过程中,综合起动发电机对发动机起动协助的作用,在制动过程中,综合起动发电机还可以作为发电机向蓄电池充电;和非混合动力汽车相比,微混合动力汽车的燃油经济性可以提高10%左右;轻混合动力轻混合动力和微混合动力结构相似,有一点不同的是其综合起动发电机是经过改进的,其输出的动力可以超过20KW;但是,轻混合动力的能量储存系统只能储存1KWh左右的能量;轻混合动力汽车只有一个很短的纯电动续航能力,但是可以在加速过程中给发动机提供很大的辅助作用;轻混合动力中的电子元件要比微混合动力中的电子元件复杂的多,且在汽车行驶过程中发挥着更大的作用;和非混合动力的汽车相比,轻混合动力汽车的燃油经济性可以提高20%-25%左右;全混合动力在全混合动力汽车上不再使用综合起动发电机,取代它的是一个独立的电动马达和交流发电机、起动机,这些装置也可以起到综合起动发电机的作用;电动马达可以独立驱动汽车行驶,尤其是在城市道路上走走停停的行驶;能量储存系统也得到了改进,这样就提高了汽车纯电动续航能力,减少了发动机的体积,从而提高燃油经济性和减少排放;与非混合动力汽车相比,全混合动力汽车的燃油消耗量可以减少40%-50%;插电式混合动力插电式混合动力汽车在结构上和全混合动力汽车相似,不同的是插电式混合动力汽车有一个比较大的能量储存系统,可以通过与外部电源连接进行充电;在蓄电池储存能量范围内,可以通过电动马达来驱动汽车行驶,但是当蓄电池的能量降到一定水平后,其运行形势就和全混合动力一样了;2.1.3再生制动原理混合动力电动汽车最重要的特点是可以回收大量的制动能量;在制动过程中,电动马达可以作为发电机来运行操作,将制动过程中的动能转换为电能储存到蓄电池中,这些电能就可以被汽车重复使用;但是,车辆的制动性能就将影响到汽车的安全性;在紧急制动状态下,汽车的制动距离要尽可能的短,还要保证制动时汽车有较好的方向稳定性;汽车具有较好的方向稳定性,就需要控制车轮的制动力分配;一般来说,制动时所需的制动力矩比电动马达产生的制动力矩大得多;因此,机械制动系统需要和电子再生制动系统同时存在,这就需要适当的设计以保证制动时的操作稳定性,不至于影响到汽车的安全性;制动时能量消耗由公式可得,一个质量为1500Kg的汽车以100km/h初速度制动到完全停止,需要消耗的动能;如果这些能量的25%可以通过再生制动系统进行回收,当忽略制动和加速过程中的空气阻力,机械摩擦和滚动阻力,假设电动马达的工作效率100%,利用公式可以估算出,这些能量可以使汽车从0km/h加速到50km/h.这就表明,当汽车行驶在城市道路上,汽车不停加速和制动,混合动力电动车的燃油经济性可以大大增加;需要注意的是,制动能量的回收量受到马达的型号和能量转换率的限制;2.1.4再生制动系统目前,通常使用的有两种再生制动方法;这些方法通常称为串联再生制动和并联制动,每种制动策略都有其优点和缺点,本文对此将进行具体讨论;并联再生制动在并联再生制动系统中,电动马达和机械制动系统同时工作,从而使汽车减速;因为机械制动系统不能独立的控制制动力,使制动时的能量转换为热能而不是电能,因此这不是最有效地再生制动方法;但是并联再生制动结构简单成本低,这就成为其一大优势;并联再生制动的机械制动系统只需要稍加修改,而且电动马达的控制算法也可以很容易在汽车上实现;这种制动方法还有一个额外的优势,当再生制动系统发生故障时,机械制动系统可以起到备用的作用;串联再生制动在串联再生制动中,电动马达只有在制动时才起作用;只有当电动马达和能量储存系统无法接受更多制动时所需的能量时,再生制动系统才起作用;串联再生制动需要独立的控制制动力矩,串联再生制动可以高效率的把动能转换为电能,这是其一项优势;但是它的不足之处在于,制动系统结构复杂,成本高;这种制动方式需要制动踏板模拟器,制动系统也需要重新设计,这都会增加其制造成本;因为制动系统需要装有传感器和信息处理器,这就会增加了结构的复杂度;2.1.5目前的再生制动系统目前大多数混合动力电动汽车的再生制动系统都是比较昂贵的电液制动系统;再生制动系统使用制动踏板模拟器来建立驾驶者的制动需求,这个制动踏板模拟器与液压制动电路独立分开;这样再将制动需求按照一定比例转换为再生制动和机械制动需求,然后将机械制动需求发送到由高压液压泵,蓄能器和比例控制阀的系统;比例控制阀根据制动需求,控制制动液以一定的预定值流到每个车轮的制动轮缸中;。
毕业论文英文参考文献与译文
Inventory managementInventory ControlOn the so-called "inventory control", many people will interpret it as a "storage management", which is actually a big distortion.The traditional narrow view, mainly for warehouse inventory control of materials for inventory, data processing, storage, distribution, etc., through the implementation of anti-corrosion, temperature and humidity control means, to make the custody of the physical inventory to maintain optimum purposes. This is just a form of inventory control, or can be defined as the physical inventory control. How, then, from a broad perspective to understand inventory control? Inventory control should be related to the company's financial and operational objectives, in particular operating cash flow by optimizing the entire demand and supply chain management processes (DSCM), a reasonable set of ERP control strategy, and supported by appropriate information processing tools, tools to achieved in ensuring the timely delivery of the premise, as far as possible to reduce inventory levels, reducing inventory and obsolescence, the risk of devaluation. In this sense, the physical inventory control to achieve financial goals is just a means to control the entire inventory or just a necessary part; from the perspective of organizational functions, physical inventory control, warehouse management is mainly the responsibility of The broad inventory control is the demand and supply chain management, and the whole company's responsibility.Why until now many people's understanding of inventory control, limited physical inventory control? The following two reasons can not be ignored:First, our enterprises do not attach importance to inventory control. Especially those who benefit relatively good business, as long as there is money on the few people to consider the problem of inventory turnover. Inventory control is simply interpreted as warehouse management, unless the time to spend money, it may have been to see the inventory problem, and see the results are often very simple procurement to buy more, or did not do warehouse departments .Second, ERP misleading. Invoicing software is simple audacity to call it ERP, companies on their so-called ERP can reduce the number of inventory, inventory control, seems to rely on their small software can get. Even as SAP, BAAN ERP world, the field ofthese big boys, but also their simple modules inside the warehouse management functionality is defined as "inventory management" or "inventory control." This makes the already not quite understand what our inventory control, but not sure what is inventory control.In fact, from the perspective of broadly understood, inventory control, shouldinclude the following:First, the fundamental purpose of inventory control. We know that the so-called world-class manufacturing, two key assessment indicators (KPI) is, customer satisfaction and inventory turns, inventory turns and this is actually the fundamental objective of inventory control.Second, inventory control means. Increase inventory turns, relying solely on the so-called physical inventory control is not enough, it should be the demand and supply chain management process flow of this large output, and this big warehouse management processes in addition to including this link, the more important The section also includes: forecasting and order processing, production planning and control, materials planning and purchasing control, inventory planning and forecasting in itself, as well as finished products, raw materials, distribution and delivery of the strategy, and even customs management processes.And with the demand and supply chain management processes throughout the process, it is the information flow and capital flow management. In other words, inventory itself is across the entire demand and supply management processes in all aspects of inventory control in order to achieve the fundamental purpose, it must control all aspects of inventory, rather than just manage the physical inventory at hand.Third, inventory control, organizational structure and assessment.Since inventory control is the demand and supply chain management processes, output, inventory control to achieve the fundamental purpose of this process must be compatible with a rational organizational structure. Until now, we can see that many companies have only one purchasing department, purchasing department following pipe warehouse. This is far short of inventory control requirements. From the demand and supply chain management process analysis, we know that purchasing and warehouse management is the executive arm of the typical, and inventory control should focus on prevention, the executive branch is very difficult to "prevent inventory" for the simple reason that they assessment indicatorsin large part to ensure supply (production, customer). How the actual situation, a reasonable demand and supply chain management processes, and thus set the corresponding rational organizational structure and is a question many of our enterprisesto exploreThe role of inventory controlInventory management is an important part of business management. In the production and operation activities, inventory management must ensure that both the production plant for raw materials, spare parts demand, but also directly affect the purchasing, sales of share, sales activities. To make an inventory of corporate liquidity, accelerate cash flow, the security of supply under the premise of minimizing Yaku funds, directly affects the operational efficiency. Ensure the production and operation needs of the premise, so keep inventories at a reasonable level; dynamic inventory control, timely, appropriate proposed order to avoid over storage or out of stock; reduce inventory footprint, lower total cost of inventory; control stock funds used to accelerate cash flow.Problems arising from excessive inventory: increased warehouse space andinventory storage costs, thereby increasing product costs; take a lot of liquidity, resultingin sluggish capital, not only increased the burden of payment of interest, etc., would affect the time value of money and opportunity income; finished products and raw materials caused by physical loss and intangible losses; a large number of enterprise resource idle, affecting their rational allocation and optimization; cover the production, operation of the whole process of the various contradictions and problems, is not conducive to improve the management level.Inventory is too small the resulting problems: service levels caused a decline in the profit impact of marketing and corporate reputation; production system caused by inadequate supply of raw materials or other materials, affecting the normal production process; to shorten lead times, increase the number of orders, so order (production) costs; affect the balance of production and assembly of complete sets.NotesInventory management should particularly consider the following two questions:First, according to sales plans, according to the planned production of the goods circulated in the market, we should consider where, how much storage.Second, starting from the level of service and economic benefits to determine howto ensure inventories and supplementary questions.The two problems with the inventory in the logistics process functions.In general, the inventory function:(1)to prevent interrupted. Received orders to shorten the delivery of goods fromthe time in order to ensure quality service, at the same time to prevent out of stock.(2)to ensure proper inventory levels, saving inventory costs.(3)to reduce logistics costs. Supplement with the appropriate time interval compatible with the reasonable demand of the cargo in order to reduce logistics costs, eliminate or avoid sales fluctuations.(4)ensure the production planning, smooth to eliminate or avoid sales fluctuations.(5)display function.(6)reserve. Mass storage when the price falls, reduce losses, to respond to disasters and other contingencies.About the warehouse (inventory) on what the question, we must consider the number and location. If the distribution center, it should be possible according to customer needs, set at an appropriate place; if it is stored in central places to minimize the complementary principle to the distribution centers, there is no place certain requirements. When the stock base is established, will have to take into account are stored in various locations in what commodities.库存管理库存控制在谈到所谓“库存控制”的时候,很多人将其理解为“仓储管理”,这实际上是个很大的曲解。
外文参考文献译文及原文【范本模板】
广东工业大学华立学院本科毕业设计(论文)外文参考文献译文及原文系部城建学部专业土木工程年级 2011级班级名称 11土木工程9班学号 23031109000学生姓名刘林指导教师卢集富2015 年5 月目录一、项目成本管理与控制 0二、Project Budget Monitor and Control (1)三、施工阶段承包商在控制施工成本方面所扮演的作用 (2)四、The Contractor’s Role in Building Cost Reduction After Design (4)一、外文文献译文(1)项目成本管理与控制随着市场竞争的激烈性越来越大,在每一个项目中,进行成本控制越发重要。
本文论述了在施工阶段,项目经理如何成功地控制项目预算成本。
本文讨论了很多方法。
它表明,要取得成功,项目经理必须关注这些成功的方法.1。
简介调查显示,大多数项目会碰到超出预算的问……功控制预算成本.2.项目控制和监测的概念和目的Erel and Raz (2000)指出项目控制周期包括测量成……原因以及决定纠偏措施并采取行动。
监控的目的就是纠偏措施的。
.。
标范围内。
3.建立一个有效的控制体系为了实现预算成本的目标,项目管理者需要建立一……被监测和控制是非常有帮助的。
项目成功与良好的沟通密。
决( Diallo and Thuillier, 2005).4.成本费用的检测和控制4.1对检测的优先顺序进行排序在施工阶段,很多施工活动是基于原来的计……用完了。
第四,项目管理者应该检测高风险活动,高风险活动最有。
..重要(Cotterell and Hughes, 1995)。
4.2成本控制的方法一个项目的主要费用包括员工成本、材料成本以及工期延误的成本。
为了控制这些成本费用,项目管理者首先应该建立一个成本控制系统:a)为财务数据的管理和分析工作落实责任人员b)确保按照项目的结构来合理分配所有的……它的变化-—在成本控制线上准确地记录所有恰..。
外文参考文献译文及原文
目录1介绍 (1)在这一章对NS2的引入提供。
尤其是,关于NS2的安装信息是在第2章。
第3章介绍了NS2的目录和公约。
第4章介绍了在NS2仿真的主要步骤。
一个简单的仿真例子在第5章。
最后,在第.8章作总结。
2安装 (1)该组件的想法是明智的做法,以获取上述件和安装他们的个人。
此选项保存downloadingtime和大量内存空间。
但是,它可能是麻烦的初学者,因此只对有经验的用户推荐。
(2)安装一套ns2的all-in-one在unix-based系统 (2)安装一套ns2的all-in-one在Windows系统 (3)3目录和公约 (4)目录 (4)4运行ns2模拟 (6)ns2程序调用 (6)ns2模拟的主要步骤 (6)5一个仿真例子 (8)6总结 (12)1 Introduction (13)2 Installation (15)Installing an All-In-One NS2 Suite on Unix-Based Systems (15)Installing an All-In-One NS2 Suite on Windows-Based Systems (16)3 Directories and Convention (17)Directories and Convention (17)Convention (17)4 Running NS2 Simulation (20)NS2 Program Invocation (20)Main NS2 Simulation Steps (20)5 A Simulation Example (22)6 Summary (27)1介绍网络模拟器(一般叫作NS2)的版本,是证明了有用在学习通讯网络的动态本质的一个事件驱动的模仿工具。
模仿架线并且无线网络作用和协议(即寻址算法,TCP,UDP)使用NS2,可以完成。
一般来说,NS2提供用户以指定这样网络协议和模仿他们对应的行为方式。
大学生心理健康问题外文文献最新译文
大学生心理健康问题外文文献最新译文XXX。
as evidenced by the high-profile cases of XXX students at Virginia Tech and Northern XXX。
these incidents are not representative of the broader public health XXX students as they are among same-aged non-students。
and the number and XXX。
they are not XXX illness.One of the major XXX。
lack of knowledge about available resources。
and XXX must work to ce these barriers XXX and support for mental health.XXX students is the lack of resources available on XXX form of counseling or mental health services。
these resources are often overburdened and underfunded。
This can lead to long wait times for appointments and limited access to specialized care。
To address this issue。
colleges and XXX and services.It is also XXX college students。
such as those from XXX or those with pre-existing mental health ns。
文献翻译参考
毕业设计(论文)译文及原稿译文题目一贸易能带来经济增长?原稿题目一Does Trade Cause Growth?原稿出处一Frankel J , and Romer D .Does Trade Cause Growth ? [J] . American Economic Review . 1999,89 (3): 379 -399.贸易能带来经济增长?1.构建模型A背景我们基本的想法可以表述为使用三个简单的等式模型。
首先,国家i的平均收入的函数包括:与其他国家经济交往(简称“国际贸易”),国内经济交往(“国内贸易”)和其他相关因素。
(1).这里是个人收入,是国际贸易,是国内贸易,是与收入相关的其他影响因素。
已正如大量的文献对贸易描述的那样,贸易可以通过很多途径影响收入,贸易通过比较优势,开发来自大市场的递增收益,通过交流和旅游交换思想,通过投资和开发新产品传播科技,从而使得专业分工更加显著。
因为各种因素相互作用共同促进,我们的方法不能确定具体是哪种贸易方式影响收入。
另外两个方程式包含了国际贸易和国内贸易的决定因素。
国际贸易的函数包括,是一个国家与另一个国家的接近度和其他因素。
(2)类似的,国内贸易的函数包括国家大小,和其他因素。
(3)三个等式中的剩余因素,和,很有可能相互关联。
比如说,那些拥有良好的交通系统或者政府的政策的国家,能够促进竞争并能够依赖市场分配资源,具有地理优势给他们带来大量的国际和国内贸易,贸易又给他们带来了大量的收入。
我们假设分析的关键是判定国家的地理特征(他们的和)与另外的等式(1)和(3)是没有关联的。
相似度和规模不会被收入或者其他因素影响,而政府政策可以影响收入。
我们回顾引言,除了作用于该国居民人数与外国人或者其他人之间的相互影响,我们很难想出有效的方法证明相似度和规模可以影响收入。
给出P和S与不相关联的假设。
通过变量Y,T,W,P和S,我们可以计算公式(1):P,S与T,W有关[通过公式(2)和公式 (3)] ,并且与无关(通过鉴别假设)。
文献译文
- -浙江万里学院商学院市场营销,2009级1班王金圣会展与营销系2009011354翁飞 学生姓名 专业班级 指导教师 系 别 学生学号 毕业论文外文文献译文外文文献译文标题:定价策略资料来源:《定价策略与技巧》作者:Tomas T. Nagle Reed K. Holden 价格制定和战略定价的区别在于公司对市场状况的不同反应和如何有效地管理。
这就是为什么那些市场份额小、技术含量不高的公司往往能获得巨额回报的原因所在。
战略定价时结合相关的营销决策、竞争决策和财务决策所制定的赢利性价格。
对于大多数公司来说,战略定价不仅要求定价观念上的改变,还要求在定价时间、定价方法和定价决策者等方面改变。
一、成本加成定价的误区历史上,成本加成定价法是最为常用的定价,因为它能够带来审慎的财务氛围。
按照这种观点,审慎的财务是通过对每一个产品和服务的定价来实现的,这种定价需要在充分合理地考虑所有的成本后加上一个适当的利润额。
从理论上看,这种方法是一个简单的赢利性指南。
但实际上,它只是一种导致平庸财务绩效的计划。
这种成本导向的定价法存在一个致命缺陷。
在大多数行业中,要在产品价格确定之前产品单位成本是不可能的。
为什么?因为单位成本会随着产品的销量而发生变化。
事实上,产品成本中有很大一部分“固定成本”需要“分摊”到每件产品上,“分摊”量的多少取决于销售量的大小,销售量则随着价格变动,因此,单位成本是一个变动指标。
为了解决如何确定单位成本的问题,成本导向的定价者只能荒谬的假设制定产品价格时不考虑销售数量对成本的影响,不考虑产品价格对销售数量的影响以及销售量对成本的影响假设,使得定价可能在无形中损害了公司的长远利益。
在这方面,“王安试验室”生产的世界上第一台文字处理机的定价经历就很有代表性。
1976年,王安公司成功地推出这种产品,并很快占领了市场,这使公司得以迅速地成长。
然而,到20世纪80年代中期,带有文字处理软件的个人电脑逐渐成为该产品的强大竞争对手。
外文文献及译文
外文文献及译文译文一作者:Wikipedia来源:/wiki/History_of_the_Indian_caste_system,2007年12 年15月访问。
历史上印度的种姓制度起源关于种姓制度的发源地,至今仍然模糊。
2001年,由犹他州大学的Michael率领的人员进行遗传研究,发现印度人和欧洲人具有相称的种姓职级,上层种姓与欧洲人最为相似,而低种姓是越来越像亚洲人。
研究人员认为,印欧发言者从西北大陆进入印度,参与或是取代了原dravidian发言者的发言。
后来他们可能已经建立了种姓制度,并把自己放在较高种姓。
研究报告的结论认为,印度的种姓“是最有可能成为原亚洲在遗传亲缘关系种姓的起源,其在西欧亚大陆外加剂的影响下形成亚洲人和欧洲人在职级方面的相关性差异。
””因为本研究采取了单一的地理区域即印度的样本,所以调查结果是否可以一概而论仍有待调查1995年乔安娜等人进行了早期的研究,斯坦福大学已得出的结论是“三个独特基因种姓群体没有明确的分离线”,尽管如此“还是能推断出一些根据种姓类聚的从属关系”。
2002-03年度汤匙,吉维席尔德等人得出结论认为“自从新世纪以来印度部落和种姓的人口基因获得主要来自南部和西部的亚洲人,并已获得从外部地区流入的有限基因”。
2006年印度国家生物制品研究所进行遗传研究,从32部落和45种姓群体的男子测试样本中得出结论认为:印度人已获得极少数印欧发言者的基因。
根据2006年伊斯梅尔等人的一项研究表明,印度孕产妇基因库中的绝大数(> 98 %)与印第安欧洲和dravidian的基因有或多或少的统一。
,而inavsions后,晚世纪解决可能已大部分是男性介导。
研究得出结论认为,“低种姓群体有可能起源于同层次进行记名表决时出现内部的部落群体与蔓延的新石器时代的农民,比雅利安人的到来大大提前”,“印支欧洲人建立了自己的上种姓的同时,这已经发展成种姓一样内部结构的部落”。
文献翻译译文-模具的历史发展
1 模具的历史发展David O.Kazmer.Injection mold design engineering.Hanser Gardner Publications,2007.模具的出现可以追溯到几千年前的陶器和青铜器铸造,但其大规模使用却是随着现代工业的掘起而发展起来的。
19世纪,随着军火工业(枪炮的弹壳)、钟表工业、无线电工业的发展,冲模得到广泛使用。
二次大战后,随着世界经济的飞速发展,它又成了大量生产家用电器、汽车、电子仪器、照相机、钟表等零件的最佳方式。
从世界范围看,当时美国的冲压技术走在前列——许多模具先进技术,如简易模具、高效率模具、高寿命模具和冲压自动化技术等,其大多起源于美国;而瑞士的精冲、德国的冷挤压技术、苏联对塑性加工的研究也处于世界先进行列。
50年代,模具行业工作重点是根据用户的要求,制作能满足产品要求的模具。
模具设计多凭经验,参考已有图纸和感性认识,对所设计模具零件的机能缺乏真切了解。
从1955年到1965年,是冲压工业的探索和开发时代——对模具主要零部件的机能和受力状态进行了数学分桥,并把这些知识不断应用于现场实际,使得冲压技术在各方面有飞跃的发展。
其结果是总结出了模具的设计原则,并使得压力机械、冲压材料、加工方法、模具结构、模具材料、模具制造方法、自动化装置等领域更新换代,并向实用化的方向前进,从而使冲压加工进入生产优良产品的第一阶段。
进入70年代,模具进入高速化、机械化、精密化、安全化发展的第二阶段。
在这个过程中不断涌现各种高效率、高寿命、高精度、多功能的自动化模具。
其代表是多个工位的级进模和十几个工位的多工位传递模。
在此基础上又发展出既有连续冲压工位又有多滑块成形工位的压力机—弯曲机。
在此期间,日本站到了世界最前列——其模具加工精度进入了微米级,模具寿命,合金钢制造的模具达到了几千万次,硬质合金钢制造的模具达到了几亿次。
在冲压模具中,每分钟冲压次数,小型压力机通常为200至300次,最高为1200次至1500次。
外文文献原稿和译文
(空一行)原□□稿(空一行) IntroductionThe "jumping off" point for this paper is Reengineering the Corporation, by Michael Hammer and James Champy . The paper goes on to review the literature on BPR. It explores the principles and assumptions behind reengineering, looks for commonfactors behind its successes or failures, examines case studies, and presents alternatives to "classical" reengineering theory . The paper pays particular attention to the role of information technology in BPR. In conclusion, the paper offers somespecific recommendations regarding reengineering. Old Wine in New BottlesThe concept of reengineering traces its origins back to management theories developedas early as the nineteenth century . The purpose of reengineering is to "make all your processes the best-in-class." Frederick Taylor suggested in the 1880's that managers use process reengineering methods to discover the best processes for performing work, and that these processes be reengineered to optimize productivity. BPR echoes the classical belief that there is one best way to conduct tasks. In Taylor's time, technology did not allow large companies to design processes in across-functional or cross-departmental manner. Specialization was the state-of-theart method to improve efficiency given the technology of the time.(下略)正文内容:新罗马“TimesNewRoman ”字体,小四号字。
外文参考文献译文及原文
广东工业大学华立学院本科毕业设计(论文)外文参考文献译文及原文系部城建学部专业土木工程年级 2011级班级名称 11土木工程9班学号 23031109000学生姓名刘林指导教师卢集富2015 年5 月目录一、项目成本管理与控制 0二、Project Budget Monitor and Control (1)三、施工阶段承包商在控制施工成本方面所扮演的作用 (2)四、The Contractor's Role in Building Cost Reduction After Design (4)一、外文文献译文(1)项目成本管理与控制随着市场竞争的激烈性越来越大,在每一个项目中,进行成本控制越发重要。
本文论述了在施工阶段,项目经理如何成功地控制项目预算成本。
本文讨论了很多方法。
它表明,要取得成功,项目经理必须关注这些成功的方法。
1.简介调查显示,大多数项目会碰到超出预算的问……功控制预算成本。
2.项目控制和监测的概念和目的Erel and Raz (2000)指出项目控制周期包括测量成……原因以及决定纠偏措施并采取行动。
监控的目的就是纠偏措施的...标范围内。
3.建立一个有效的控制体系为了实现预算成本的目标,项目管理者需要建立一……被监测和控制是非常有帮助的。
项目成功与良好的沟通密...决( Diallo and Thuillier, 2005)。
4.成本费用的检测和控制4.1对检测的优先顺序进行排序在施工阶段,很多施工活动是基于原来的计……用完了。
第四,项目管理者应该检测高风险活动,高风险活动最有...重要(Cotterell and Hughes, 1995)。
4.2成本控制的方法一个项目的主要费用包括员工成本、材料成本以及工期延误的成本。
为了控制这些成本费用,项目管理者首先应该建立一个成本控制系统:a)为财务数据的管理和分析工作落实责任人员b)确保按照项目的结构来合理分配所有的……它的变化--在成本控制线上准确地记录所有恰...围、变更、进度、质量)相结合由于一个工程项目......虑时间价值影响后的结果。
3D打印外文文献翻译最新译文
3D打印外文文献翻译最新译文3D XXX years。
especially in the field of industrial product design。
The manufacturing of digital product models through 3D printing has e a trend and a hot topic。
With the gradual maturity of -level 3D printing devices。
the rise of the global 3D printing market has been promoted。
According to a research report by Global Industry Analysis Inc。
the global 3D printing market XXX n by 2018.2 The ns of 3D printingThe ns of 3D XXX。
In the medical field。
3D printing has been used to create prosthetics。
implants。
XXX industry。
3D printing has been used to create XXX industry。
3D printing has been used to create unique and XXX possibilities of 3D printing seem endless。
and it is expected to XXX industries.3 The future of 3D printingThe future of 3D printing is promising。
with the potential to transform the way we XXX 3D XXX advance。
XXX财务分析体系外文文献翻译最新译文
XXX财务分析体系外文文献翻译最新译文XXX the use of DuPont financial analysis system in XXX DuPont system breaks down the return on equity (ROE) into three components: net profit margin。
asset turnover。
and financial leverage。
Using data from a sample of listed companies。
the study finds that the DuPont system is effective in XXX。
the XXX that it should be used in n with other financial analysis tools.In recent years。
there has been a growing interest in using financial analysis tools to XXX financial analysis system is one such tool that has XXX in the 1920s to analyze the performance of its own ns。
Since then。
it has been widely used in the financial XXX.The DuPont system breaks down the ROE into three components: net profit margin。
asset XXX。
and financial leverage。
The net profit margin measures the XXX efficiency of the company's use of its assets to generate sales。
5、外文文献翻译(附原文)产业集群,区域品牌,Industrial cluster ,Regional brand
外文文献翻译(附原文)外文译文一:产业集群的竞争优势——以中国大连软件工业园为例Weilin Zhao,Chihiro Watanabe,Charla-Griffy-Brown[J]. Marketing Science,2009(2):123-125.摘要:本文本着为促进工业的发展的初衷探讨了中国软件公园的竞争优势。
产业集群深植于当地的制度系统,因此拥有特殊的竞争优势。
根据波特的“钻石”模型、SWOT模型的测试结果对中国大连软件园的案例进行了定性的分析。
产业集群是包括一系列在指定地理上集聚的公司,它扎根于当地政府、行业和学术的当地制度系统,以此获得大量的资源,从而获得产业经济发展的竞争优势。
为了成功驾驭中国经济范式从批量生产到开发新产品的转换,持续加强产业集群的竞争优势,促进工业和区域的经济发展是非常有必要的。
关键词:竞争优势;产业集群;当地制度系统;大连软件工业园;中国;科技园区;创新;区域发展产业集群产业集群是波特[1]也推而广之的一个经济发展的前沿概念。
作为一个在全球经济战略公认的专家,他指出了产业集群在促进区域经济发展中的作用。
他写道:集群的概念,“或出现在特定的地理位置与产业相关联的公司、供应商和机构,已成为了公司和政府思考和评估当地竞争优势和制定公共决策的一种新的要素。
但是,他至今也没有对产业集群做出准确的定义。
最近根据德瑞克、泰克拉[2]和李维[3]检查的关于产业集群和识别为“地理浓度的行业优势的文献取得了进展”。
“地理集中”定义了产业集群的一个关键而鲜明的基本性质。
产业由地区上特定的众多公司集聚而成,他们通常有共同市场、,有着共同的供应商,交易对象,教育机构和其它像知识及信息一样无形的东西,同样地,他们也面临相似的机会和威胁。
在全球产业集群有许多种发展模式。
比如美国加州的硅谷和马萨诸塞州的128鲁特都是知名的产业集群。
前者以微电子、生物技术、和风险资本市场而闻名,而后者则是以软件、计算机和通讯硬件享誉天下[4]。
外文文献翻译原文+译文
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。
20外文文献翻译原文及译文参考样式
20外⽂⽂献翻译原⽂及译⽂参考样式华北电⼒⼤学科技学院毕业设计(论⽂)附件外⽂⽂献翻译学号: 0819******** 姓名:宗鹏程所在系别:机械⼯程及⾃动化专业班级:机械08K1指导教师:张超原⽂标题:Development of a High-PerformanceMagnetic Gear年⽉⽇⾼性能磁齿轮的发展1摘要:本⽂提出了⼀个⾼性能永磁齿轮的计算和测量结果。
上述分析的永磁齿轮有5.5的传动⽐,并能够提供27 Nm的⼒矩。
分析表明,由于它的弹簧扭转常数很⼩,因此需要特别重视安装了这种⾼性能永磁齿轮的系统。
上述分析的齿轮也已经被应⽤在实际中,以验证、预测其效率。
经测量,由于较⼤端齿轮传动引起的磁⼒齿轮的扭矩只有16 Nm。
⼀项关于磁齿轮效率损失的系统研究也展⽰了为什么实际⼯作效率只有81%。
⼀⼤部分磁损耗起源于轴承,因为机械故障的存在,此轴承的备⽤轴承在此时是必要的。
如果没有源于轴的少量磁泄漏,我们估计能得到⾼达96%的效率。
与传统的机械齿轮的⽐较表明,磁性齿轮具有更好的效率和单位体积较⼤扭矩。
最后,可以得出结论,本⽂的研究结果可能有助于促进传统机械齿轮向磁性齿轮发展。
关键词:有限元分析(FEA)、变速箱,⾼转矩密度,磁性齿轮。
⼀、导⾔由于永久磁铁能产⽣磁通和磁⼒,虽然⼏个世纪过去了,许多⼈仍然着迷于永久磁铁。
,在过去20年的复兴阶段,正是这些优点已经使得永久磁铁在很多实际中⼴泛的应⽤,包括在起重机,扬声器,接头领域,尤其是在永久磁铁电机⽅⾯。
其中对永磁铁的复兴最常见于效率和转矩密度由于永磁铁的应⽤显著提⾼的⼩型机器的领域。
在永久磁铁没有获取⾼度重视的⼀个领域是传动装置的领域,也就是说,磁⼒联轴器不被⼴泛⽤于传动装置。
磁性联轴器基本上可以被视为以传动⽐为1:1磁⼒齿轮。
相⽐标准电⽓机器有约10kN m/m的扭矩,装有⾼能量永久磁铁的磁耦有⾮常⾼的单位体积密度的扭矩,变化范围⼤约300–400 kN 。
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高层建筑设计与城市空间
高层建筑形式在古代就已有了,早在公元前五百多年的古巴比伦曾经建造了现在号称世界七大奇迹之一的“空中花园”,根据记载,其形式非常之华丽壮观,放置在任何空间之中都可以说是一道绝美的风景。
近代随着科学技术的发展,尤其是钢铁、电梯的出现以及后来钢筋混凝土的应用,为高层建筑发展创造了前所未有的机遇,高层建筑也成为城市空间中一道独特的风景,其中以美国的高层建筑发展最为活跃,如1885年的芝加哥家庭保险大楼被公认为第一幢摩天建筑,而纽约的曼哈顿区更是高楼云集;近年来我国的高层建筑也发展迅速,如上海的金茂大厦88层,高420.5米。
随着结构理论和技术的发展,高层建筑结构形式趋于多样化,高层建筑的表现形式也多种多样,但随之所带来的弊端也越来越多的表现出来,在成为城市风景的同时如何恰当的融入城市空间成为高层建筑设计的一个重要任务,也是使高层建筑设计趋于完善所追求的一种理念。
城市空间是人类生活和生产所需要的重要因素,它为居民提供各种活动的可能。
这个可以说是城市空间比较科学性的定义,而本文提到的城市空间则更具体更形象,主要指城市内的建筑物、道路、绿地、广场、公共服务设施等实体以及由这些实体所构成的立体空间,也是人处在其中能真实、直观感受到的空间。
高层建筑是否与所处的城市空间融洽,其评价标准相当一部分取决于公众的感受,简单的说就是人处在所创造空间中的感受;所以一位建筑设计者在进行高层建筑设计时要充分考虑所创造出来的空间(无论是内部还是外部)给予使用者的感受。
这些是理论上要求一位建筑设计师要考虑的因素也是作为一名建筑师应该承担的责任,而且还可以据此评价一位建筑师的设计能力和水平及其职业道德。
事实上在进行一项高层建筑设计时,开发商受利益的驱使往往不会考虑建筑与环境的关系,此时,规划部门所出台的各种条文政策及规范将扮演着重要角色,它强制性的要求必须顾及城市环境,营造舒适的城市空间。
可以看出,高层建筑设计与城市空间的协调以及城市空间的营造是通过两方面的共同作用来完成的,即建筑设计和规划。
下面就从建筑设计和城市规划两方面谈谈高层建筑设计与城市空间的关系。
一.建筑设计
1、充分发挥广场的作用
高层建筑由于其体量的巨大,往往给街道空间一种突然的压迫感,使人感觉好像从一个大空间突然进入一个小空间,这是由于高层建筑的体量所造成的对比。
因此凡是处在街道两旁体量巨大的高层建筑在设计时应该对其进行后退处理,并在其退出的用地上设计一广场空间,这个广场空间将起到空间的缓冲作用;而且由于高层建筑的建筑面积远远超出其用地面积,容纳的人员较多,出入口人流密度相对较大,后退出的广场空间也起到缓解交通压力的作用;从另外一方面讲,广场空间往往在街道空间以及城市空间中起到非常重要作用,能够给公众留下较深的印象,也往往能成为城市的节点,这就是共享空间的好处。
有的建筑大师甚至直接设计成下沉式的广场,如日本建筑大师叽崎新设计的日本筑波中心的下沉式广场,独特的广场空间造型,以人和环境为设计重点,不仅为公众提供了一个舒适的安静的休闲场所,而且使建筑塔楼的形象特征更加突出。
这种下沉式的广场往往更容易给人留下印象,就空间形式而言它是一种非常富有情趣的空间。
因此在进行高层建筑设计时广场和建筑应该作为一体来考虑。
2、高层建筑主体设计
对于一个城市而言,高层建筑往往具有一定的代表性和象征性,可以反映一个城市经济水平和发展程度,选择合理的造型就显的尤为重要。
高层建筑由于其结构形式的限制以及使用功能的要求,在造型上往往追随于建筑的结构形式,而不能有太多的变化,有的高层建筑甚至直接将结构形式外露不加修饰。
高层建筑的主体部分是它的塔楼,塔楼的表现形式对高层建筑的造型起着决定性的作用,现今国外和国内的许多高层建筑都有着独特的外形和明显的识别性,对一个城市具有一定的代表性,这可以说是高层建筑存在的一个原因。
随着近年来资源短缺问题的出现,全球提出了可持续发展,而高层建筑就环保节能方面来说是很浪费的,随之就出现了“生态型”建筑的概念,如生态建筑师――诺曼·福斯特设计的法兰克福商业银行总部大厦在强调象征意义和功能的同时,就引入生态的概念,是世界上第一座“生态型”超高层建筑。
其建筑平面呈三角形,宛如三叶花瓣夹着一支花茎:花瓣部分是办公空间,花茎部分为中空大厅。
中空大厅起自然通风作用,同时还为建筑内部创造了丰富的景观。
而气候设计大师――杨经文设
计的马来西亚吉隆坡梅纳拉大厦则体现了利用空中开放空间连通建筑内外,贯彻“生物气候大楼”思想,引入了大量的植物,立面上螺旋上升的垂直绿化和底部斜坡的绿化都有助于调节气候,尽可能地拉近了人与自然的距离,较好地完成了室内外空间的过渡与衔接。
同时对形成良好的城市空间环境也是一种深化。
可以看出目前高层建筑设计的一个新要求就是要实现“生态节能型”。
高层建筑主体的下部分――裙房虽然对整个城市影响较小,但它对于街道的尺度和人情化空间的创造等方面却有着重要的影响。
建筑的裙楼立面设计一般不同于上部立面,需要进行细致的设计,从而使下部空间丰富多彩而不至于感到苍白;并要体现人的尺度,因为裙房部分跟公众视觉接触较密切,对街道空间感影响也较大。
而高层建筑的最上部分――屋顶对整个建筑形象起到强化个性的作用,虽然它较少影响到生态环境,但对塑造建筑的标志性、丰富城市天际线具有重要的作用,因此应根据建筑的基座、楼身等因素加以塑造。
3、巧妙的运用一些处理手法
高层建筑的塔楼部分虽然变化的余地不大,但是底层部分却可以进行一些巧妙的处理来丰富空间形式。
一般可以采用底层架空和入口缩进的手法。
底层架空的处理手法是现代建筑的特征之一,它可以在高密度的环境中争取到宝贵的用地,把城市的道路、广场和建筑有机地结合在一起,形成通透的、公共的开放空间,给市民以小憩之地;同时还可以改善人流、视觉拥挤的状况,连通几个主要的公共场所,以增加城市空间的层次。
高层建筑临近城市道路布置时,入口空间凹入建筑下部可以避免主体的被迫后退(用地非常紧张的情况下),争取基地面积的有效使用,缓解入口处各种矛盾冲突;并有可能在建筑的形体设计、空间组织等方面形成新颖的构思,这种入口后退架开的处理不仅空间层次丰富而且给人的印象也深刻。
二.规划设计
1、避免高层建筑密集
高层建筑的密集虽然对于城市办公等条件方便有利,却给城市空间带来很多压力,造成城市空间和城市交通的拥挤,甚至是一些史料不及的污染和危害,比如一些高层建筑玻璃幕墙的大面积使用造成以前未出现过的光污染;还有就是形成高压风带和风口,这些会造成意想不到的后果。
因此在规划设计中要对区域内
的高层建筑密度进行限制,避免高层建筑的集中分布。
2、高层建筑与城市街道
高层建筑一般分布在城市中商业发达的地段,这些地段的街道本身交通荷载就较大,高层建筑将大大增加这些街道的交通压力,分布在这些街道两侧的高层建筑要尽量控制其层数和高度,同时在规划设计时要对这些街道进行扩展,加大其通行能力。
3、控制超高层建筑数量
超高层建筑往往以其象征性和代表性而存在,实际上这类建筑既不经济又不合理,一些已建成的超高层建筑投入使用后表明收益并不乐观,可以说仅仅是体现城市形象,提高城市知名度。
高层建筑已走过百年历史,从其出现之日起就成为城市的焦点,其形式和风格也不断的发展变化着,我国的高层建筑虽然相对发达国家起步较晚,但已经取得了很大的成就,像北京、上海、深圳等城市的高层建筑可以说代表了中国高层建筑的发展史,高层建筑设计与城市空间的融合也正不断的完善发展。
参考文献:
[1]R·里尔城市空间同济大学出版社,1991
[2]刘顺校周湘津高层建筑设计天津科学技术出版社,1997
[3]夏祖华黄伟康城市空间设计东南大学出版社,1992。