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National Institutes of Health

NIEHS REPORT onHealth Effects from Exposure to Power-Line Frequency Electric and Magnetic FieldsPrepared in Response to the 1992 Energy Policy Act(PL 102-486, Section 2118)National Institute of Environmental Health SciencesNational Institutes of HealthDr. Kenneth Olden, DirectorPrepared by theNIEHS EMF-RAPID Program StaffNIH Publication No. 99-4493Supported by the NIEHS/DOEDEPARTMENT OF HEALTH & HUMAN SERVICES Public Health ServiceNational Institutes of HealthNational Institute ofEnvironmental Health SciencesP. O. Box 12233Research Triangle Park, NC 27709 May 4, 1999Dear Reader:In 1992, the U.S. Congress authorized the Electric and Magnetic Fields Research and Public Information Dissemination Program (EMF-RAPID Program) in the Energy Policy Act. The Congress instructed the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health and the U.S. Department of Energy (DOE) to direct and manage a program of research and analysis aimed at providing scientific evidence to clarify the potential for health risks from exposure to extremely low frequency electric and magnetic fields (ELF-EMF). The EMF-RAPID Program had three basic components: 1) a research program focusing on health effects research, 2) information compilation and public outreach and 3) a health assessment for evaluation of any potential hazards arising from exposure to ELF-EMF. The NIEHS was directed to oversee the health effects research and evaluation, and the DOE was given the responsibility for overall administration of funding and engineering research aimed at characterizing and mitigating these fields. The Director of the NIEHS was mandated upon completion of the Program to provide this report outlining the possible human health risks associated with exposure to ELF-EMF. The scientific evidence used in preparation of this report has undergone extensive scientific and public review. The entire process was open and transparent. Anyone who wanted “to have a say” was provided the opportunity.The scientific evidence suggesting that ELF-EMF exposures pose any health risk is weak. The strongest evidence for health effects comes from associations observed in human populations with two forms of cancer: childhood leukemia and chronic lymphocytic leukemia in occupationally exposed adults. While the support from individual studies is weak, the epidemiological studies demonstrate, for some methods of measuring exposure, a fairly consistent pattern of a small, increased risk with increasing exposure that is somewhat weaker for chronic lymphocytic leukemia than for childhood leukemia. In contrast, the mechanistic studies and the animal toxicology literature fail to demonstrate any consistent pattern across studies although sporadic findings of biological effects have been reported. No indication of increased leukemias in experimental animals has been observed.The lack of connection between the human data and the experimental data (animal and mechanistic) severely complicates the interpretation of these results. The human data are in the "right" species, are tied to "real life" exposures and show some consistency that is difficult to ignore. This assessment is tempered by the observation that given the weak magnitude of these increased risks, some other factor or common source of error could explain these findings. However, no consistent explanation other than exposure to ELF-EMF has been identified.Page 2Epidemiological studies have serious limitations in their ability to demonstrate a cause and effect relationship whereas laboratory studies, by design, can clearly show that cause and effect are possible. Virtually all of the laboratory evidence in animals and humans and most of the mechanistic work done in cells fail to support a causal relationship between exposure to ELF-EMF at environmental levels and changes in biological function or disease status. The lack of consistent, positive findings in animal or mechanistic studies weakens the belief that this association is actually due to ELF-EMF, but it cannot completely discount the epidemiological findings.The NIEHS concludes that ELF-EMF exposure cannot be recognized at this time as entirely safe because of weak scientific evidence that exposure may pose a leukemia hazard. In my opinion, the conclusion of this report is insufficient to warrant aggressive regulatory concern. However, because virtually everyone in the United States uses electricity and therefore is routinely exposed to ELF-EMF, passive regulatory action is warranted such as a continued emphasis on educating both the public and the regulated community on means aimed at reducing exposures. The NIEHS does not believe that other cancers or non-cancer health outcomes provide sufficient evidence of a risk to currently warrant concern. The interaction of humans with ELF-EMF is complicated and will undoubtedly continue to be an area of public concern. The EMF-RAPID Program successfully contributed to the scientific knowledge on ELF-EMF through its support of high quality, hypothesis-based research. While some questions were answered, others remain. Building upon the knowledge base developed under the EMF-RAPID Program, meritorious research on ELF-EMF through carefully designed, hypothesis-driven studies should continue for areas warranting fundamental study including leukemia. Recent research in two areas, neurodegenerative diseases and cardiac diseases associated with heart rate variability, have identified some interesting and novel findings for which further study is ongoing. Advocacy groups have opposing views concerning the health effects of ELF-EMF. Some advocacy groups want complete exoneration and others want a more serious indictment. Our conclusions are prudent and consistent with the scientific data. I am satisfied with the report and believe it provides a pragmatic, scientifically-driven basis for any further regulatory review.I am pleased to transmit this report to the U.S. Congress.Sincerely,Kenneth Olden, Ph.D.DirectorNIEHS EMF-RAPID P ROGRAM S TAFF Gary A. Boorman, D.V.M., Ph.D., Associate Director for Special Programs, Environmental Toxicology Program and Director, EMF-RAPID ProgramNaomi J. Bernheim, M.S., Biologist, Office of Special Programs, Environmental Toxicology Program and Program Assistant, EMF-RAPID ProgramMichael J. Galvin, Ph.D., Health Scientist Administrator, Division of Extramural Research and Training and Extramural Program Administrator, EMF-RAPIDProgramSheila A. Newton, Ph.D., Director, Office of Policy, Planning and EvaluationFred M. Parham, Ph.D., Staff Scientist, Laboratory of Computational Biology and Risk AnalysisChristopher J. Portier, Ph.D., Associate Director for Risk Assessment, Environmental Toxicology Program; Chief, Laboratory of Computational Biology and RiskAnalysis; and Coordinator, EMF Hazard EvaluationMary S. Wolfe, Ph.D., Associate Coordinator, EMF Hazard Evaluation, Environmental Toxicology ProgramA CKNOWLEDGEMENTSThis report would not have been possible without the concerted and generous help of literally hundreds of research scientists. Many of the scientists who wrote the articles, which are cited in this report, attended our science review symposia where their research was carefully evaluated and critiqued. Their patience with our questions and their professional attitude in evaluating their own work was extraordinary and is greatly appreciated. We are also indebted to the many scientists from outside of the electric and magnetic fields (EMF) research community who participated in our symposia and spent time and effort evaluating these data on our behalf; this provides a clear example of the dedication of scientists concerned about health issues.Special thanks are extended to the 30 scientists who attended the Working Group Meeting in June 1998. Their hard work and conscientious effort led to one of the most concise and clear reviews of the extremely low frequency (ELF) EMF literature ever developed. The thousands of man-hours extended by this group in such a short period of time provided us with a background document on ELF-EMF health risks that made this report a much simpler task. We wish especially to thank Dr. Arnold Brown for attending our public meetings on the Working Group Report; his extensive experience and insightful comments helped to make these meetings a great success. We would also like to thank Dr. Brown and Dr. Paul Gailey for reviewing this report prior to its release and Mr. Fred Dietrich for advising us on exposure issues during the preparation of this document. Finally we would like to acknowledge the U.S. Department of Energy as our partner in the EMF-RAPID Program and its EMF program officer, Dr. Imre Gyuk.T ABLE OF C ONTENTSEXECUTIVE SUMMARY (i)I NTRODUCTION (i)NIEHS C ONCLUSION (ii)B ACKGROUND (iii)Program Oversight and Management (iii)ELF-EMF Health Effects Research (iv)Information Dissemination and Public Outreach (iv)Health Risk Assessment of ELF-EMF Exposure (v)INTRODUCTION (1)Funding (2)Oversight and Program Management (3)ELF-EMF Health Effects Research (3)Information Dissemination and Public Outreach (4)Literature Review and Health Risk Assessment (6)DO ELECTRIC AND MAGNETIC FIELDS POSE A HEALTH RISK? (9)S CIENTIFIC E VIDENCE S UPPORTING T HIS C ONCLUSION (10)Background on the Limitations of Epidemiology Studies (10)Childhood Cancers (12)Adult Cancers (15)Non-Cancer Findings in Humans (16)Animal Cancer Data (19)Non-Cancer Health Effects in Experimental Animals (23)Studies of Cellular Effects of ELF-EMF (25)Biophysical Theory (29)HOW HIGH ARE EXPOSURES IN THE U.S. POPULATION? (31)CONCLUSIONS AND RECOMMENDATIONS (35)Previous Panel Reviews (35)NIEHS Conclusion (35)Recommended Actions (37)Future Research (38)REFERENCES (41)E XECUTIVE S UMMARYIntroductionElectrical energy has been used to great advantage for over 100 years. Associated with the generation, transmission, and use of electrical energy is the production of weak electric and magnetic fields (EMF). In the United States, electricity isusually delivered as alternating current that oscillates at 60 cycles per second(Hertz, Hz) putting fields generated by this electrical energy in the extremely low frequency (ELF) range.Prior to 1979 there was limited awareness of any potential adverse effects fromthe use of electricity aside from possible electrocution associated with directcontact or fire from faulty wiring. Interest in this area was catalyzed with thereport of a possible association between childhood cancer mortality and proximity of homes to power distribution lines. Over the next dozen years, the U.S.Department of Energy (DOE) and others conducted numerous studies on theeffects of ELF-EMF on biological systems that helped to clarify the risks andprovide increased understanding. Despite much study in this area, considerabledebate remained over what, if any, health effects could be attributed to ELF-EMF exposure.In 1992, the U.S. Congress authorized the Electric and Magnetic Fields Research and Public Information Dissemination Program (EMF-RAPID Program) in theEnergy Policy Act (PL 102-486, Section 2118). The Congress instructed theNational Institute of Environmental Health Sciences (NIEHS), National Institutes of Health and the DOE to direct and manage a program of research and analysisaimed at providing scientific evidence to clarify the potential for health risks from exposure to ELF-EMF. The EMF-RAPID Program had three basic components:1) a research program focusing on health effects research, 2) informationcompilation and public outreach and 3) a health assessment for evaluation of any potential hazards arising from exposure to ELF-EMF. The NIEHS was directedto oversee the health effects research and evaluation and the DOE was given theresponsibility for overall administration of funding and engineering researchaimed at characterizing and mitigating these fields. The Director of the NIEHSwas mandated upon completion of the Program to provide a report outlining thepossible human health risks associated with exposure to ELF-EMF. Thisdocument responds to this requirement of the law.This five-year effort was signed into law in October 1992 and provisions of thisAct were extended for one year in 1997. The Program ended December 31, 1998.The EMF-RAPID Program was funded jointly by Federal and matching privatefunds and has been an extremely successful Federal/private partnership withsubstantial financial support from the utility industry. The NIEHS received$30.1 million from this program for research, public outreach, administration and the health assessment evaluation of ELF-EMF. In addition to EMF-RAPIDProgram funds from the DOE, the NIEHS contributed $14.5 million for support of extramural and intramural research including long-term toxicity studies conducted by the National Toxicology Program.NIEHS ConclusionThe scientific evidence suggesting that ELF-EMF exposures pose any health risk is weak. The strongest evidence for health effects comes from associationsobserved in human populations with two forms of cancer: childhood leukemia and chronic lymphocytic leukemia in occupationally exposed adults. While thesupport from individual studies is weak, the epidemiological studies demonstrate, for some methods of measuring exposure, a fairly consistent pattern of a small,increased risk with increasing exposure that is somewhat weaker for chroniclymphocytic leukemia than for childhood leukemia. In contrast, the mechanisticstudies and the animal toxicology literature fail to demonstrate any consistentpattern across studies although sporadic findings of biological effects (includingincreased cancers in animals) have been reported. No indication of increasedleukemias in experimental animals has been observed.The lack of connection between the human data and the experimental data (animal and mechanistic) severely complicates the interpretation of these results. Thehuman data are in the “right” species, are tied to “real-life” exposures and showsome consistency that is difficult to ignore. This assessment is tempered by theobservation that given the weak magnitude of these increased risks, some otherfactor or common source of error could explain these findings. However, noconsistent explanation other than exposure to ELF-EMF has been identified.Epidemiological studies have serious limitations in their ability to demonstrate acause and effect relationship whereas laboratory studies, by design, can clearlyshow that cause and effect are possible. Virtually all of the laboratory evidence in animals and humans and most of the mechanistic work done in cells fail tosupport a causal relationship between exposure to ELF-EMF at environmentallevels and changes in biological function or disease status. The lack of consistent, positive findings in animal or mechanistic studies weakens the belief that thisassociation is actually due to ELF-EMF, but it cannot completely discount theepidemiological findings.The NIEHS concludes that ELF-EMF exposure cannot be recognized as entirelysafe because of weak scientific evidence that exposure may pose a leukemiahazard. In our opinion, this finding is insufficient to warrant aggressiveregulatory concern. However, because virtually everyone in the United Statesuses electricity and therefore is routinely exposed to ELF-EMF, passiveregulatory action is warranted such as a continued emphasis on educating both the public and the regulated community on means aimed at reducing exposures. The NIEHS does not believe that other cancers or non-cancer health outcomes provide sufficient evidence of a risk to currently warrant concern.The interaction of humans with ELF-EMF is complicated and will undoubtedlycontinue to be an area of public concern. The EMF-RAPID Program successfully contributed to the scientific knowledge on ELF-EMF through its support of highquality, hypothesis-based research. While some questions were answered, others remain. Building upon the knowledge base developed under the EMF-RAPIDProgram, meritorious research on ELF-EMF through carefully designed,hypothesis-driven studies should continue for areas warranting fundamental study including leukemia. Recent research in two areas, neurodegenerative diseases and cardiac diseases associated with heart rate variability, have identified someinteresting and novel findings for which further study is ongoing.BackgroundProgram Oversight and ManagementThe 1992 Energy Policy Act created two committees to provide guidance anddirection to this program. The first, the Interagency Committee (IAC), wasestablished by the President of the United States and composed of representatives from the NIEHS, the DOE and seven other Federal agencies with responsibilities related to ELF-EMF. This group receives the report from the NIEHS Directorand must prepare its own report for Congress. The IAC had responsibility fordeveloping a strategic research agenda for the EMF-RAPID Program, facilitating interagency coordination of Federal research activities and communication to the public and monitoring and evaluating the Program.The second committee, the National EMF Advisory Committee (NEMFAC),consisted of representatives from public interest groups, organized labor, stategovernments and industry. This group was involved in all aspects of theEMF-RAPID Program providing advice and critical review to the DOE and theNIEHS on the design and implementation of the EMF-RAPID Program’sactivities.ELF-EMF Health Effects ResearchThe EMF-RAPID Program’s health effects research initiative relied upon accepted principles of hazard identification and risk assessment to establish priorities. All studies supported by the NIEHS and the DOE under this program were selected for their potential to provide solid, scientific data on whetherELF-EMF exposure represents a human health hazard, and if so, whether risks are increased under exposure conditions in the general population. Research efforts did not focus on epidemiological studies (i.e. those in the human population) because of time constraints and the number of ongoing, well-conducted studies. The NIEHS health effects research program focused on mechanistic, cellular and laboratory studies in the areas of neurophysiology, behavior, reproduction, development, cellular research, genetic research, cancer and melatonin. Mechanistic, cellular and laboratory studies are part of the overall criteria used to determine causality in interpreting epidemiological studies. In this situation, the most cost-effective and efficient use of the EMF-RAPID Program’s research funds was clearly for trying to clarify existing associations identified from population studies. The DOE research initiatives focused on assessment of exposure and techniques of mitigation.The EMF-RAPID Program through the combined efforts of the NIEHS and the DOE radically changed and markedly improved the quality of ELF-EMF research. This was accomplished by providing biological and engineering expertise to investigators and emphasizing hypothesis-driven, peer-reviewed research. Four regional facilities were also set-up where state-of-the-art magnetic field exposure systems were available for in-house and outside investigators to conduct mechanistic research. The EMF-RAPID Program through rigorous review and use of multi-disciplinary research teams greatly enhanced the understanding of the interaction of biological systems with ELF-EMF. Information Dissemination and Public OutreachThe EMF-RAPID Program provided the public, regulated industry and scientists with useful, targeted information that addressed the issue of uncertainty regarding ELF-EMF health effects. Two booklets, a question and answer booklet onELF-EMF and a layman’s booklet addressing ELF-EMF in the workplace, were published. A telephone information line for ELF-EMF was available where callers could request copies of ELF-EMF documents and receive answers to standard questions from operators. The NIEHS also developed a web-site for the EMF-RAPID Program where all of the Program’s documents are on-line and links are available to other useful sites on ELF-EMF. Efforts were made to include the public in EMF-RAPID Program activities through sponsorship of scholarships to meetings; holding open, scientific workshops; and setting aside a two-month period for public comment and review on ELF-EMF and the workshop reports. In addition, the NIEHS sponsored attendance of NEMFACmembers at relevant scientific meetings and at each of the public comment meetings.Health Risk Assessment of ELF-EMF ExposureIn preparation of the NIEHS Director’s Report, the NIEHS developed a process to evaluate the potential health hazards of ELF-EMF exposure that was designed to be open, transparent, objective, scholarly and timely under the mandate of the 1992 Energy Policy Act. The NIEHS used a three-tiered strategy for collection and evaluation of the scientific information on ELF-EMF that included: 1) three science review symposia for targeted ELF-EMF research areas, 2) a working group meeting and 3) a period of public review and comment. Each of the three symposia focused on a different, broad area of ELF-EMF research: mechanistic and cellular research (24-27 March 1997, Durham, NC), human population studies (12-14 January 1998, San Antonio, TX) and laboratory human and clinical work (6-9 April 1998, Phoenix, AZ). These meetings were aimed at including a broad spectrum of the research community and the public in the evaluation of ELF-EMF health hazards, identifying key research findings and providing opinion on the quality of this research. Discussion reports from small discussion groups held for specific topics were prepared for each meeting.Following the symposia, a working group meeting (16-24 June 1998, Brooklyn Park, MN) was held where a scientific panel reviewed historical and novel evidence on ELF-EMF and determined the strength of the evidence for human health and biological effects. Stakeholders and the public attended this meeting and were given the opportunity to comment during the process. The Working Group conducted a formal, comprehensive review of the literature for research areas identified from the symposia as being important to the assessment ofELF-EMF-related biological or health effects. Separate draft documents covering areas of animal carcinogenicity, animal non-cancer findings, physiological effects, cellular effects, theories and human population studies (epidemiology studies) in children and adults for both occupational and residential ELF-EMF exposures were rewritten into a single book. The Working Group characterized the strength of the evidence for a causative link between ELF-EMF exposure and disease in each category of research using the criteria developed by the International Agency for Research on Cancer (IARC).The IARC criteria fall into four basic categories: sufficient, limited, inadequate and evidence suggesting the lack of an effect. After critical review and discussion, members of the Working Group were asked to determine the categorization for each research area; the range of responses reflected the scientific uncertainty in each area. A majority of the Working Group members concluded that childhood leukemia and adult chronic lymphocytic leukemia from occupational exposure were areas of concern. For other cancers and for non-cancer health endpoints, the Working Group categorized the experimental data asproviding much weaker evidence or no support for effects from exposure to ELF-EMF.Following the Working Group Meeting, the NIEHS established a formal review period for solicitation of comments on the symposia and Working Group reports. The NIEHS hosted four public meetings (14-15 September 1998, Tucson, AZ;28 September, Washington, DC; 1 October 1998, San Francisco, CA; and5 October 1998, Chicago, IL) where individuals and groups could voice their opinions; the meetings were recorded and transcripts prepared. In addition, the NIEHS received 178 written comments that were also reviewed in preparation of this report. The remarks that NIEHS received covered many areas related to ELF-EMF and provided insight about areas of concern on behalf of the public, researchers, regulatory agencies and industry.I NTRODUCTIONElectricity is used to the benefit of people all over the world. Wherever electricity is generated, transmitted or used, electric fields and magnetic fields are created. These fields are a direct consequence of the presence and/or motion of electric charges. It is impossible to generate and use electrical energy without creating these fields; hence they are an inevitable consequence of our reliance on this form of energy. Electrical energy is generally supplied as alternating current where the electricity flows in one direction and then in the other to complete a cycle. The number of cycles completed in a fixed period of time (such as a second) is known as the frequency and is generally measured in units of Hertz (Hz), which are cycles per second. In the United States, electricity is usually delivered as 60 Hz alternating current; 50 to 60 Hz cycles are generally referred to as the power-line frequency of alternating current electricity. Just as alternating current electricity has a frequency, so do the associated electric and magnetic fields (EMF). Thus, 60 Hz alternating current electricity will generate a 60 Hz electric field and a60 Hz magnetic field. EMF with cycle frequencies of greater than 3 Hz and less that 3000 Hz is generally referred to as extremely low frequency (ELF) EMF. In addition to magnetic fields associated with electricity, the earth also has a static magnetic field (frequency of 0 Hz) that varies by location from approximately 30 to 50 µT.Electricity has been used, to great advantage, for 100 years and with this widespread use, there has been limited awareness of any potential adverse health effects other than effects caused by direct contact such as electrocution or by faulty wiring such as fire. Research into potential health effects caused by the ELF-EMF resulting from indirect exposure to electrical energy has been underway for several decades. The catalyst that sparked increased study in this area of research was the 1979 report by Wertheimer and Leeper (1) that children living near power lines had an increased risk for developing cancer. Since that initial finding, there have been numerous studies of human populations, animals and isolated cells aimed at clarification of the observations of Wertheimer and Leeper and others. Despite this multitude of research, considerable debate remains over what, if any, health effects can be attributed to ELF-EMF exposure. In 1992, under the Energy Policy Act (PL 102-486, Section 2118), the U.S. Congress instructed the National Institute of Environmental Health Sciences(NIEHS), National Institutes of Health and the U.S. Department of Energy (DOE) to direct and manage a program of research and analysis aimed at providing scientific evidence to clarify the potential for health risks from exposure toELF-EMF. This resulted in formation of the EMF Research and Public Information Dissemination Program (EMF-RAPID Program). The EMF-RAPID Program had three basic components: 1) a research program focusing on health effects research primarily through mechanistic studies of ELF-EMF and engineering research targeting measurement, characterization and management of ELF-EMF; 2) information compilation and dissemination through brochures, public outreach and an ELF-EMF information line for communicating with the public; and 3) a health assessment including an analysis of the research data aimed at summarizing the strength of the evidence for evaluation of any hazard possibly arising from exposure to ELF-EMF. The NIEHS was directed to oversee the health effects research and evaluation and the DOE was given responsibility for engineering research aimed at characterizing and mitigating these fields. Under the Energy Policy Act, the Director of the NIEHS is mandated upon completion of the EMF-RAPID Program to provide a report outlining the possible human health risks associated with exposure to ELF-EMF. This document responds to this requirement of the law.FundingThe EMF-RAPID Program was funded jointly by Federal and matching private funds; through fiscal year 1998, authorized funding for this program was approximately $46 million. Administration of funding for the EMF-RAPID Program was the responsibility of the DOE with funds for NIEHS-sponsored program activities transferred from the DOE to the NIEHS. The EMF-RAPID Program has been an extremely successful Federal/private partnership with substantial financial support from the utility industry. The NIEHS received $30.1 million from this program for research, public outreach, administration and the health assessment evaluation of ELF-EMF. Of the funds received, the NIEHS spent the majority (89%) for research through grants and contracts. The remainder was used for public outreach/administration (2%) and the health risk evaluation (9%). In addition to EMF-RAPID Program funds from the DOE, the NIEHS contributed $14.5 million for support of extramural grants and contracts and intramural research as well as long-term toxicity studies conducted by the National Toxicology Program.。

半桥式DC-DC变换器的系统

（4）半桥式变换器由两个电容器和两个开关管组成两个桥，桥的对角线接变压器的原边绕组，故称半桥变换器。半桥式变换器减小了原边开关管的电压应力，结构简单，功率器件少，所以在中小功率场合得到广泛应用。本文设计电路将 400V 恒定直流输入变为 5V 稳定直流输出，输出功率较低，所以我们采用半桥式变压器。 1.3 本文研究的内容本文研究的内容主要包括： (1) 研究半桥式 DC-DC 电力变换电路的工作原理。 (2) 研究 PWM 调制方法的机理和半桥式 DC-DC 变换电路的控制方法。 (3) 设计从 400V 到 5V 的半桥式 DC-DC 变换器。 (4) 采用 MATLAB 工具对所设计系统进行仿真研究。
1 绪论
1.1 研究背景随着科技的发展，在人们的日常生活中，电力已成为与生产生活息息相关的一部分，在各个场合，人们都需要各式各样的电力来为其服务，然而并不是所有的电力都能在一开始就能满足需要，于是就要求有电力变换的过程。直流- 直流变换器（DC-DC）作为一种应用广泛变换器广泛应用于远程及数据通讯、计算机、办公自动化设备、工业仪器仪表、军事、航天等领域，涉及到国民经济的各行各业。按额定功率的大小来划分，DC-DC 可分为 750W 以上、750W～1W 和 1W 以下 3 大类。进入 20 世纪 90 年代， DC-DC 变换器在低功率范围内的增长率大幅度提高，其中 6W～25W DC-DC 变换器的增长率最高，这是因为它们大量用于直流测量和测试设备、计算机显示系统、计算机和军事通讯系统。由于微处理器的高速化，DC-DC 变换器由低功率向中功率方向发展是必然的趋势，所以 251W～750W 的 DC-DC 变换器的增长率也是较快的，这主要是它用于服务性的医疗和实验设备、工业控制设备、远程通讯设备、多路通信及发送设备，DC-DC 变换器在远程和数字通讯领域有着广阔的应用前景。 DC-DC 变换器将一个固定的直流电压变换为可变的直流电压，这种技术被广泛应用于无轨电车、地铁、列车、电动车的无级变速和控制，同时使上述控制具有加速平稳、快速响应的性能，并同时收到节约电能的效果。用直流斩波器代替变阻器可节约 20％～30％的电能。直流斩波器不仅能起到调压的作用(开关电源)，同时还能起到有效抑制电网侧谐波电流噪声的作用。 DC/DC 变换器现已商品化，模块采用高频 PWM 技术，开关频率在 500kHz 左右, 功率密度为 0.31W/cm3～1.22W/cm3。随着大规模集成电路的发展，要求电源模块实现小型化，因此就要不断提高开关频率和采用新的电路拓扑结构。目前，已有一些公司研制生产了采用零电流开关和零电压开关技术的二次电源模块，功率密度有较大幅度的提高。电子产业的迅速发展极大地推动了开关电源的发展。高频小型化的开关电源及其技术已成为现代电子设备供电系统的主流。在电子设备领域中，通常将整流器称为一次电源，而将 DC/DC 变换器称为二次电源。一次电源的作用是将单相或三相交流电网变换成标值为 48V 的直流电源。目前，在电子设备中用的一次电源中，传统的相控式

曼哈顿计划讲解

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基于自由现金流的蒙牛乳业价值评估

摘要随着我国社会主义市场经济的迅速发展，资本市场的不断完善，价值评估在公司进行财务管理、对外投资、兼并收购中的应用日益频繁。

目前，价值评估理论在经过了长期的研究后，已经形成了完整的理论体系，并在实际工作中得到广泛应用。

在此基础上，文章研究公司价值评估的相关理论、实践问题，尤其是利用自由现金流量折现法评估公司价值。

在肯定了自由现金流量折现法的实际可操作性以及模型改良后，对该方法在理论和应用中存在的其他问题提出对策建议。

关键词：自由现金流；蒙牛乳业；价值评估AbstractWith the rapid development of our country socialist market economy, the continuous improvement of the capital market, value evaluation in company financial management, the application of foreign investment, merger and acquisition is becoming more and more frequent. At present, the value assessment theory after the long-term research, has formed a complete theoretical system, and is widely applied in the practical work. On this basis, the article studies the value of the company evaluate the relevant theories and practical problems, especially the free cash flow discount method is used to evaluate the value of the company. In the affirmation of the free cash flow discount method after actual operability, and modified model, in theory and application of this method in other problems of the countermeasures and Suggestions are put forward.Keywords:Freecashflow;Mengniu;Valueevaluation目录1 绪论1.1研究背景 (1)1.2研究的意义 (1)1.3国内外研究现状 (2)1.3.1国内研究现状 (2)1.3.1国外研究现状 (1)2公司价值评估的相关理论2.1公司价值评估的概念 (4)2.2价值评估的方法 (4)2.3基于自由现金流的企业价值评估 (4)2.3.1自由现金流量折现法的基本原则 (4)2.3.2自由现金流量模型的因素分析 (5)2.3.3自由现金流与企业价值的相关性 (5)3蒙牛企业的价值评估案例分析3.1行业分析 (6)3.1.1消费量及普及率大幅上升 (6)3.1.2竞争日益激烈 (6)3.1.3行业现状 (6)3.2蒙牛乳业背景 (7)3.3蒙牛乳业的评估过程 (7)3.3.1对自由现金流量的预测 (7)3.3.2折现率的估计 (9)3.3.3蒙牛乳业的价值估算 (10)4结论与建议4.1对蒙牛乳业的自由现金流价值评估的总结 (12)4.2对自由现金流的价值评估的建议 (12)4.2.1健全国内市场环境 (12)4.2.2法律制度的完善 (13)4.2.3积极完善信息披露制度 (13)参考文献 (14)致谢 (15)1 绪论1.1 研究背景二十世纪五十年代初期，伴随着产权市场的出现，专门从事企业买卖的产权市场迅速发展，使人们日益清楚地认识到，在市场经济条件下，作为商品生产者的企业本身也是一种商品。

2013美国成人超重和肥胖管理指南

2013 AHA/ACC/TOS成人超重和肥胖管理指南：美国心脏病学会/美国心脏协会实践指南专责组/肥胖协会报告2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults:A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines andThe Obesity SocietyMichael D. Jensen, Donna H. Ryan, Caroline M. Apovian, Jamy D. Ard, Anthony G. Comuzzie, Karen A. Donato, Frank B.Hu, Van S. Hubbard, John M. Jakicic, Robert F. Kushner, Catherine M. Loria, Barbara E. Millen, Cathy A. Nonas, F.Xavier Pi-Sunyer, June Stevens, Victor J. Stevens, Thomas A. Wadden, Bruce M. Wolfe and Susan Z. YanovskiCirculation. published online November 12, 2013;Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Copyright © 2013 American Heart Association, Inc. All rights reserved.Print ISSN:0009-7322. Online ISSN: 1524-4539本文网上版及更新信息和服务，位于互联网：/content/early/2013/11/11/01.cir.0000437739.71477.ee.citationData Supplement (unedited) a/content/suppl/2013/11/07/01.cir.0000437739.71477.ee.DC1.html2013 AHA/ACC/TOS成人超重和肥胖管理指南美国心脏病学会/美国心脏协会实践指南专责组/肥胖协会报告美国心肺康复协会（American Association of Cardiovascular and Pulmonary Rehabilitation），美国药师协会（American Pharmacists Association），美国营养协会（American Society for Nutrition），美国预防心脏病协会（American Society for Preventive Cardiology），美国高血压协会（American Society of Hypertension），黑人心脏病医生协会（Association of Black Cardiologists），全国血脂协会（National Lipid Association），预防心血管护理协会（Preventive Cardiovascular Nurses Association），内分泌协会（The Endocrine Society）和妇女心脏（WomenHeart）：全国妇女心脏病联合会（The National Coalition for Women with Heart Disease）认可专家组成员Michael D. Jensen, MD, Co-ChairDonna H. Ryan, MD, Co-ChairCaroline M. Apovian, MD, FACP Catherine M. Loria, PhD, FAHA*Jamy D. Ard, MD Barbara E. Millen, DrPH, RD Anthony G. Comuzzie, PhD Cathy A. Nonas, MS, RD Karen A. Donato, SM* F. Xavier Pi-Sunyer, MD,MPHFrank B. Hu, MD, PhD,FAHAJune Stevens, PhDVan S. Hubbard, MD, PhD*Victor J. Stevens, PhD John M. Jakicic, PhD Thomas A. Wadden, PhD Robert F. Kushner, MD Bruce M. Wolfe, MD Susan Z. Yanovski, MD*方法学成员Harmon S. Jordan, ScDKarima A. Kendall, PhDLinda J. LuxRoycelynn Mentor-Marcel, PhD,MPHLaura C. Morgan, MAMichael G. Trisolini, PhD, MBAJanusz Wnek, PhDACCF/AHA专责组成员Jeffrey L. Anderson, MD, FACC, FAHA, ChairJonathan L. Halperin, MD, FACC, FAHA, Chair-ElectNancy M. Albert, PhD, CCNS, CCRN, FAHA Judith S. Hochman, MD, FACC, FAHABiykem Bozkurt, MD, PhD, FACC, FAHA Richard J. Kovacs, MD, FACC, FAHARalph G. Brindis, MD, MPH, MACC E. Magnus Ohman, MD, FACC Lesley H. Curtis, PhD, FAHA Susan J. Pressler, PhD, RN, FAAN,FAHADavid DeMets, PhD Frank W. Sellke, MD, FACC, FAHA Robert A. Guyton, MD, FACC Win-Kuang Shen, MD, FACC, FAHA预防指南分会Sidney C. Smith, Jr, MD, FACC, FAHA, ChairGordon F. Tomaselli, MD, FACC, FAHA, Co-Chair*当然委员。

医院风险管理

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风险管理的要素
2018/10/18
mkyy
20
风险管理的基本原理
1.识别风险陈述
2.分析
风险消除
5.控制
风险
4.跟踪
3.计划
整个过程的核心依据是需要一个不断优化更新的风险评估文档
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风险管理的构成要素
内部环境
监控信息和沟通控制活动风险管理目标制定事项识别风险评估
2018/10/18 mkyy 31
各类人员在风险管理中的地位和职责
(3)风险管理员。风险管理员是指某一组织内的部门或业务经理。他与企业内其他管理者一起，在各自的职责范围内建立并维护有效的风险管理框架。担当监督风险管理进度和帮助其他管理人员在企业内向上、向下和横向报告有关风险信息的职责，并可以成为企业风险管理委员会的一员。 (4)内部审计人员。内部审计人员在企业风险管理的监控中占有重要的地位，这一职责作为其日常职责的一部分。他们可能通过对管理者风险管理过程的充分性和有效性进行监控、检查、评估、报告和提出改进建议来帮助管理者和决策成履行其职责。
另外，也有人将风险可以分为纯粹风险和投机风险两类。纯粹风险，是指有可
能带来损失的风险，如各种形式的天灾人祸。投机风险，是指既有可能带来损失，又有可能带来机会的风险。如股票投资，既可以为投资者带来丰厚的利润，也可能使投资者遭受重大的损失。
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风险的分类

静态风险是指由于自然力量的非常变动或人类行为的错误导致损失发生的风险。例如水灾、旱灾、地震、瘟疫、雷电等自然原因发生的风险；火灾、爆炸、员工伤害、破产等由于某些人疏忽大

戴德梁行大五人格现状的讨论.pdf

3．2 研究工具3.2.1 大五人格问卷简版（NEO-FFI）该问卷是Costa和McCrae在对1985年版本的NEO-PI-R进行项目因素分析的基3.2.2 绩效考核成绩从上表可以看出，戴德梁行客户经理群体在谨慎性维度上的得分最高，其次分别是外向性、友善性、开放性，得分最低的维度是神经质。

4.1.2 该行客户经理在大五人格各维度上的性别差异如上表，大五人格五个维度的性别差异在开放性维度上显著性最高（p<0.001），男性的开放性显著高于女性；其次在外向性、谨慎性两个维度上差异也较为显著（p<0.01），具体表现为男性的外向性、谨慎性均高于女性。

由表可知，大五人格中神经质维度对任务绩效有显著的负预测性，能解释总体的变异。

在进行了三次回归分析后，大五人格中的开放性、友善性、外向性三个维度都进入了回归模型，切模型的总体回归效果显著。

这三个维度共解释了情境绩效 4%的变异。

通过进一步分析这三个维度逐步进入回归模型的顺序可以得知，Figure 4: model of confirmatory factory analysis注：Extraver=外向性，Agreeabl=亲和力，Conscien=责任心，Neurotic=情绪稳定性，Openness=开明性。

LISREL 软件输出了这一模型同数据的具体拟合指标如下。

模型的卡方Chi-squares）为109.96，自由度（degree of freedom, df）为80，因此方值和自由度的比（Chi-squares/df）为109.96/80=1.37，小于 5 这一临界值水平（这一指标越小表示模型与数据的拟合情况越好）。

模型的比较拟合指数（comparative fit index, CFI）为0.89、非正态拟合指数（non-normed fit index, NNFI）为0.86，虽然没有达到.90之上，但由于比较接近，我们认为都处于可接受范围之内。

DPPH法测定胡萝卜素的抗氧化活性

DPPH法测定胡萝⼘素的抗氧化活性⽬录摘要 ....................................................................................................................................... - 1 - Abstract .................................................................................................................................. - 2 - 第⼀章绪论................................................................................................... - 3 -1.1 果蔬的主要抗氧化活性物质 ................................................................................. - 3 -1.1.1 茄红素 ........................................................................................................... - 3 -1.1.2 类黄酮 ........................................................................................................... - 3 -1.1.3 花青素 ........................................................................................................... - 4 -1.2 果蔬抗氧化作⽤机理 ............................................................................................. - 4 -1.3 果蔬抗氧化活性的评价⽅法 ................................................................................. - 5 -1.3.1 Rancimat法对果蔬提取物进⾏抗氧化活性研究........................................ - 5 -1.3.2 β-胡萝⼘素-亚油酸乳化液氧化法 ............................................................... - 5 -1.3.3 ⼆苯代苦味酰基⾃由基(DPPH·)法............................................................. - 6 -1.3.4 硫代巴⽐妥酸反应物(TBAS)值法 .............................................................. - 7 -1.3.5 FRAP(ferric reducing/antiox idant power assay)法 ....................................... - 7 -1.4 本研究的意义和内容 ............................................................................................. - 7 -1.4.1 本研究的意义 ............................................................................................... - 7 -1.4.2 本研究的内容 ............................................................................................... - 8 - 第⼆章实验材料和内容............................................................................... - 9 -2.1 材料与仪器 ............................................................................................................. - 9 -2.1.1 实验材料 ....................................................................................................... - 9 -2.1.2 实验仪器 ....................................................................................................... - 9 -2.1.3 试剂 ............................................................................................................... - 9 -2.2 实验内容 ................................................................................................................. - 9 -2.2.1 胡萝⼘素的提取 ........................................................................................... - 9 -2.2.2 在DPPH体系中测定抗氧化性................................................................. - 10 - 第三章实验结果与讨论............................................................................. - 12 -3.1 胡萝⼘素提取液的抗氧化性 ............................................................................... - 12 -3.2 β-胡萝⼘素的抗氧化性......................................................................................... - 12 -3.3 茶多酚的抗氧化性 ............................................................................................... - 13 -3.4 维⽣素C的抗氧化性 .......................................................................................... - 14 -3.5 维⽣素E的抗氧化性........................................................................................... - 15 - 第四章结论................................................................................................. - 17 - 展望............................................................................................................................. - 18 - 参考⽂献............................................................................................................................. - 19 - 致谢............................................................................................................................. - 21 - 附录............................................................................................................................. - 22 -DPPH法测定胡萝⼘素的抗氧化活性摘要：胡萝⼘中含有⼤量的β-胡萝⼘素，摄⼊⼈体消化器官后，可以转化成维⽣素A，是⽬前最安全补充维⽣素A的产品。

有机膦离子液体的结构及性质研究

organic phosphine functional ionic liquids with different cationic structure is: IL-8 > IL-3 > IL-2
≈ IL-5 > IL-4. Under the same extraction conditions, the relationship between functionalized
asymmetry, bidentate cationic bifunctional symmetry, bidentate cationic monofunctional
asymmetry and bidentate dicationic bifunctional symmetry), and was characterized by FT-IR,
取条件下，功能化离子液体结构与萃取能力关系为：双齿双阳离子双功能化对称
性离子液体 > 双齿阳离子双功能化对称性离子液体 > 单齿阳离子单功能化不
对称性离子液体 ≈ 双齿阳离子双功能化不对称性离子液体。
关键词：功能化离子液体，
黏度，
电导率，
I
稀土，
萃取
Structure of Phosphine-functionailzed Ionic Liquids and
现添加盐析剂可以促进离子液体萃取稀土 Nd(Ⅲ)；同时通过 logD-log[IL]斜率法
表明，添加 LiNTf 2 时后，萃取机理由中性络合机理转变成了离子缔合机理。当阴
离子为 NTf 2 - 时，不同阳离子结构的有机膦功能化离子液体萃取 0.005 M LiNTf 2
的 Nd(Ⅲ)溶液的萃取能力大小为：IL-8 > IL-3 > IL-2 ≈ IL-5 > IL-4。在相同萃

企业如何防范外汇风险

摘要伴随着世界经济和金融形势的变化，外汇汇率这一作为国际金融关系乃至是国际经济关系正常发展的纽带，己经渗透到包括经济生活的一切领域，我国各涉外单位尤其是外贸企业，正越来越强烈地感知到外汇风险所带来的巨大影响。

因此，分析外汇风险带给我国外贸企业的影响以及企业当前所面临的各种外汇风险，并找出相应的风险管理防范措施，有效地规避风险具有重大的理论和现实意义。

、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、、本文主要采用理论和案例研究的方法研究我国外贸企业外汇风险管理。

第一，本文对外汇风险理论进行了系统的阐述，认为我国的外汇风险主要是由人民币汇率变动带来的，并将外贸企业的外汇风险主要划分为三大类：交易风险、会计风险和经济风险。

第二，本文通过回顾我国汇率制度的变化，发现我国外贸企业的外汇风险是伴随着几十年来我国汇率制度的改革推进而逐步产生的。

作者在回顾我国各时期的汇率制度、以及分析人民币汇率风险现状的基础上，从不同的角度探究汇率变动对外贸企业的影响。

第三，本文通过分析我国外汇企业的外汇风险管理现状与不足，尤其对不足之处展开了论述，引出我国外贸企业如何管理其外汇风险。

作者认为汇率的变动是导致外贸企业外汇风险的罪魁祸首，所以对汇率走势的判断是进行一切外汇风险管理的基础。

在对人民币未来汇率走势判断的基础上，本文根据外汇风险的不同分类、不同的宏微观角度、针对外汇风险管理现存的问题，分别提出相应的外汇风险管理应对措施，以供外贸企业进行多角度的选择风险管理策略。

最后，本文结论为我国外贸企业在防范外汇风险过程中面临的一些主客观问题还有待进一步研究解决，为此，本文也提出建议，要从多方面努力营造风险防范的环境，我国外贸企业应首先立足于自我防范，积极研究和使用各种防范措施，达到提高外贸企业风险管理水平的目的。

关健词：外汇风险管理，外贸企业，人民币汇率，金融避险工具目录第1 章. 绪论 (1)1.1 选题背景 (1)1.2 研究现状 (2)1.2.1 国外情况 (2)1.2.2 国内情况 (3)1.3 研究方法与创新之处 (4)第2 章. 外汇风险相关理论概述 (6)2.1 外汇风险概念 (6)2.2 外汇风险的构成及特点 (6)2.3.外汇风险产生的原因 (6)2.4 外汇风险的种类 (7)2.4.1 交易风险 (8)2.4.2 经济风险 (8)2.4.3 会计风险 (8)第3 章. 不同汇率制度下的外汇风险对我国外贸企业的影响 (9)3.1 我国的汇率制度 (9)3.1.1 2005 年汇率改革前人民币汇率制度 (9)3.1.2 我国现行汇率制度 (10)3.2 人民币汇率风险的现状 (10)3.2.1 人民币兑美元汇率风险 (10)3.2.2 人民币兑其他主要货币汇率风险 (11)3.3 汇率变动如何对外贸企业产生影响 (11)3.3.1 对进出口总体的影响 (12)3.3.2 对不同贸易方式的影响 (12)3.3.3 对不同企业类型的影响 (13)3.3.4 对不同产品类型的影响 (14)第4 章. 我国外贸企业外汇风险管理中存在的主要问题 (16)4.1 总体现况 (16)4.2 风险防范意识较薄弱 (17)4.3 外汇风险防范专业人才储备不足 (18)4.4 缺少完善的外汇风险管理战略 (18)4.5 风险管理的机制不明确 (19)4.6 避险金触工具的运用单一 (19)第5 章. 我国外贸企业提高外汇风险管理水平的对策研究 (20)5.1 人民币汇率走势的判断 (20)5.1.1 人民币对美元汇率历史走势 (20)5.1.2 次贷危机对美元汇率走势的影响 (21)5.1.3 人民币汇率的走势预测 (22)5.2 根据外汇风险的不同分类进行管理 (23)5.2.1 交易风险的管理 (23)5.2.2 会计风险的管理 (30)5.2.3 经济风险的管理 (32)5.3 从宏微观角度出发的外汇风险管理 (33)5.3.1 宏观角度 (34)5.3.2 微观角度 (35)5.4 针对现状不足的外汇风险管理 (36)5.4.1 增强外汇风险防范意识 (36)5.4.2 加强外汇风险防范专业人才储备 (37)5.4.3 完善自身的外汇风险管理战略 (38)5.4.4 完善风险防范的监控机制 (38)5.4.5 尝试使用多种避险金融工具 (39)结论与展望 (42)参考文献 (43)1第1 章. 绪论1.1 选题背景伴随着世界经济和金融形势的变化，外汇汇率这一作为国际金融关系乃至是国际经济关系正常发展的纽带，己经渗透到包括经济生活的一切领域，我国各涉外单位尤其是外贸企业，正越来越强烈地感知到外汇风险所带来的巨大影响。

社会工作专业词汇中英文对照

社会工作专业词汇中英文对照社会调查的理论与方法Theories & Methods for Social Investigation 社会调查方法Methods for Social Investigation社会工作Social Work社会统计分析与SYSTAT应用Social Statistics Analysis & SYSTAT Application社会统计学Social Statistics社会问题研究Research on Social Problems社会心理学Social Psychology社会学概论Introduction to Sociololgy社会学简论Brief Introduction to Sociology社会学理论专题Current Issues in Theories of Socilolgy社会学问题研究Research on Problems of Sociology社会学研究方法Research Methods of Sociology社会主义财政学Finance of Socialism社会主义各国政，经体制讨论Discussion on Political & Economic Systems in Socialism社会学Sociology社会工作者Social worker案主Client社会问题Social problem社会心理Social mental state社会调查The society investigates个案社会工作Social cases work团体社会工作Social group work社区社会工作social Community work社工导论The introdution of social work社会调查应用the application for society investigates 家庭暴力Domestic violence失恋Disappoint in love人在情境中Person in situation弱势群体disadvantaged groups社会保障social security社会福利制度the social welfare system社会公德social morality单亲家庭single parent family独生子女the only child失业率rate of unemployment民工the imigrant worker社会学概论Introduction to Sociology社会工作概论Introduction to Social Work社会心理学Social Psychology国外社会学学说Sociological Theories in the West社会调查与研究方法Social Survey & Research Method社会统计与计算机应用Social Statistics and Application of Computer马克思主义社会学经典著作选读Selected Readings of Marxist-Leninist Classics社会保障与社会福利Social Security & Social Welfare当代社会学理论Modern Sociological Theories社会政策Social Policy文化人类学Cultural Anthropology中国社会思想史History of Social Theories in China人口社会学Sociology of Population农村社会学Rural Sociology城市社会学Urban Sociology家庭社会学Sociology of Family发展社会学Sociology of Development经济社会学Economic Sociology组织社会学Sociology of Organization专业英语English for Sociology社会学专题讲座Issues of Sociology民俗学Folklore Studies文化社会学Cultural Sociology宗教社会学Sociology of Religion教育社会学Sociology of Education越轨与犯罪社会学Sociology of Deviance & Crime当代社会的生活文化Life Style in Current Society西方社会思想史History of Western Social Thought社会问题Social Problems社会分层与社会流动Social Stratification & Mobility科学社会学Sociology of Education社会项目评估和统计指标Statistical Indexes & uation of Social Projects文化社会学Cultural Sociology历史社会学Historical Sociology政治社会学Political Sociology法律社会学Sociology of Law环境社会学Sociology of Environment劳动社会学Sociology of Labor公共关系Public Relations团体工作Group Work社区工作Community Work社会工作实习Practice of Social Work社会行政Social Administration数据分析技术Statistical Package & Applications for the Social Sciences贫困与发展Poverty and Development社会性别研究Gender Studies家庭社会工作Family Social Work临床社会工作Clinical Social Work社会立法Social lagislation老年社会工作Gerontological Social Work青少年越轨与矫治Juvenile Delinquency & Correction社区服务Community Services心理咨询Psychological Counseling整合社会工作实务Integrative Social Work Practice社会工作专业英语English for Social Work保险与信托Insurance and Entrustment教学实习Teaching Practice管理学Management TheoryAdministration 行政Basic assumptions and principles of ~ 行政的基本假定与原则Collaboration in 行政工作的合并In community organization 社区组织中的行政Consultation in 行政咨询Defined 行政的定义Importancy of 行政的重要性Interagency coopration 行政的重要性Shifting power in 行政分权Supervision in 行政督导social workers'club 社工俱乐部Administration in social work (journal ) 《社会工作行政》（杂志）Adolescents 青少年Drug abuse and 吸毒与青少年Health care services 青少年卫生保健服务Pregnancy and 怀孕与青少年Suicide and 自杀与青少年Adoption 领养Applicants for 申请领养人Indepengdent placements 独立安置Open 公开领养Sa fe families act 《领养与安全家庭法案》Advocacy 倡导In community organization 社区组织中的倡导In future of social work 未来社会工作中的倡导Aftercare facilities 出院后的照顾设施Agency settings 机构场所For group work 小组工作的机构场所Aging 老年Caregivers 老年照顾者Case management 个案管理Community organization and 社区组织与老年Day care centers 老年日间护理中心Health care services 老年健康照顾服务Income adequacy and 充足收入与老人Living arrangemengs and 居住安排与老年Independence and dignity in 老年的独立与尊严Mental health 心理健康Nursing home alternatives 护理院之外的选择Nursing homes 老年护理院Older americans act (1995) 《美国老年人法案》（1995）Retirement 退休Suicide and 自杀与老年Trends and 人口老化趋势White house conferences on aging 白宫老年议会AIDS epidemic 艾滋病流行Alcoholism 醺酒Almshouses 济贫院A A for marriage amd family therapy 美国婚姻与家庭治疗协会A A for the study of group work 美国小组工作研究会A A of Group worker 美国小组工作者协会A A of marriage counselors 美国婚姻辅导委员会A A of medical social worker 美国医务社会工作者协会A A of psychiatric social work 美国精神病社会工作者协会A A of schools of social work 美国社会工作院校联合会A A of social workers (aasw) 美国社会工作者协会A hospital association 美国议员联合会A psychiatric association 美国精神病学联合会A red cross 美国，自己翻译吧Assessment 评估In case work process 个案过程中的评估Associated charities 联合慈善机构Bachelor of social work (BSW)degress 社会工作学士学位Balanced budget act (1997) 《平衡预算法案》1997Caregivers 照顾者Case management 个案管理With aging population 老年人口个案惯例FutureHistory ofParameters of 个案管理的参考标准Purpose ofResearch of 个案管理研究Case study method 个案研究方法Case work 个案工作Biopsychosocial 生理心理社会因素与个案工作DefinedDrug abuse andExamples of 个案工作的案例Freudian approach and 弗洛伊德派与个案工作Generalist perpective 通才观History ofKnowledge and 知识与个案工作Methods of 个案工作的方法Multisystens approach and 多元系统趋向与个案工作Problems inProcess ofPurpose ofSanctions and 社会制裁与个案工作Trends inValus andCertification of social workers 社会工作者认证Changing nature of work 工作性质的改变Charity organization societies (COS) 慈善组织协会Cheating 欺诈Child abuse and neglect 虐待与忽视儿童Child guidance movement 儿童指导运动Child welfareAdoptionAFDC 抚养儿童家庭补助计划个人感觉应该是：Aid to Families with Dependent Children(美国)对有子女家庭补助计划child abuse and neglectdefinedfoster care 给养照顾health care serviceshome caremental health services 儿童心理健康服务origins ofprotective services 儿童保护性服务TANF 给贫困家庭临时性援助temporary aid to need family L ,need : 贫困.还是应该用need 的形容词？Chronically 慢性精神病ChurchCivil rights movement 民权运动Closed systems 封闭系统CocaineCollaboration 协办Interagency 机构间的协办Teamwork concepts and 团队工作概念与协作Commitment 服务承诺Mental hospital 精神病院服务承诺Committee operation 委员会运作Commonwealth fund 英联邦基金Community chest 公益金貌似特指社区公益基金的意思community organization 社区组织corrections and 矫正和社区组织definedexaples ofhistory ofprinciples ofprocesesses in 社区组织的过程roles inschool social work andsommunity resources 社区资源confideniality 保密consulation 咨询assumptions of 咨询的前提假设future ofprinciples ofcontimuing education (CE) 继续教育contract with America 签约美国control groups 控制组coordination 协调in communityu organization 社会组织中的协调corporate health care 矫治definedgroup work inhistory ofpractice in 矫治实践prevention in 矫治中的预防工作processes and principles ofsocial problems relatedsocial services andCouncil on social work education (CSWE) 社会工作教育委员会Curriculum Policy Statements and Educational Policy and Accreditation Standards (EPAS)课程政策声明与教育政策和审核标准curriculum statements 课程声明generalist perspective and 通才观与CSWEhistory oflobbying by CSWE的游说工作minority groups andmission statement 使命陈述与prevention andpublicationsCouncils of Aocial Afencies 社会机构委员会Counseling 辅导FamilyMarriagePremarital 婚姻辅导Rehabilitation 康复辅导SchoolAnd social workCourts 法庭Crack 快克Crack/[krAk]n.裂缝, 噼啪声v.(使)破裂, 裂纹, (使)爆裂adj.最好的, 高明的貌似这个词,没搞懂CrimeCultural dissonance 文化失调Day care centers 日间照料中心Day treatment 日间治疗Deinstitutionalization 去机构照顾貌似，没明白division of child and family services 儿童与家庭服务科Doctoral programs in social work 社会工作博士培养方案Dropout rates 辍学率Drug abuse 吸毒Adolescentys and 青少年与吸毒Alcohol 醺酒Emergency care for 虚度紧急救护Extent and cost of 吸毒的范围与代价Growth ofHallucinogens 迷幻药Inhalants 吸入剂Inpatient treatment for 吸毒住院治疗Marijuana 大麻Narcotics 麻醉剂In schoolsSedatives 镇静剂In sports worldStimulants 兴奋剂TobaccoTreatmentDrug courts 吸毒法庭Drug therapy 吸毒治疗Eclecticism 折中主义Education for social work 社会工作教育Administration andCommunity organization and Continuing educationFinancial assistanceFuture ofGeneralist practice perspective andGroup work andMinority group andMSW degreeProfessionalism and 专业主义与社会工作教育Specializaton 社会工作教育的专门化Student participation inElizabethan Poor Laws 《伊丽莎白济贫法》Employee assistance programs (EPAs) 雇员援助计划Encylopedia of Social Work 《社会工作百科全书》Enrichment in living 充实生活Evaluation 评估见：Assessment：(为征税对财产所作的)估价, 被估定的金额Evaluatio：估价, 评价, 赋值Experimental group 试验组见：control groups,控制组Faith-based social service 信心为本的社会服务FamilyBattered women 受虐妇女Battered/[~]adj.打扁了的, 敲碎的。

空气压缩机PID节能控制

1.4 本章小结 ........................................................................................................................... 7
第二章空气压缩机原理及其耗能模型 ................................................................................... 8
obvious.
Keywords: air; air compressor; energy; PID; energy saving control
ii
目
录
第一章绪论 ................................................................................................................................. 1
控制系统设计和对生产工艺的改进已经变得十分必要可行了。本课题针对空压机的控制
系统提出理想控制方案，针对工艺流程提出改进措施，来达到节能的目的，望本课题的
研究对实际工程应用具有一定的借鉴意义。
本文对空压机的原理进行了详细的分析，通过查阅相关文献对空压机的运行系统和
压缩工艺流程有了一个全面的认识，指出传统的压缩机控制系统存在的排气不稳定、吸
2.1 空气压缩机的分类 .......................................................................................................... 8

自动灌溉系统的设计

自动灌溉系统的设计电子与信息工程学院本科毕业论文论文题目基于PLC控制的自动灌溉系统的学生姓名学号业电气工程及其自动化班级指导教师 103521008 专2014年5月摘要摘要水资源的合理利用具有十分重要的意义。

相比发达国家，目前我国灌溉方式还存在一定差距。

因此农业灌溉自动化成为一个重要的研究方向。

PLC具有优良的技术性能，利用PLC控制的灌溉系统更加智能化、运行的可靠性更高。

该设计介绍了可编程控制器(PLC)在自动节水灌溉控制系统中的应用，能根据不同类型的土地进行分类灌溉。

系统按照A、B、C三种不同类型的作物的需水量分别采用不同灌溉模式，系统包括执行机构和控制机构两部分，执行机构主要是电动机作为驱动源，通过控制各电机的启动和停止来控制水泵工作，从而给作物进行灌溉。

控制机构主要是可编程控制器。

为了减少水泵电机的启动电流，减轻对电网形成的冲击，减少能耗，系统采用Y-?启动。

关键词:PLC;自动灌溉;Y-?启动I湖北科技学院学士学位论文ABSTRACTRational use of water resources is of great significance. Comparedto developed countries,China’s irrigation methods are still some gaps. Therefore,irrigation automation has become animportant research direction. PLC has excellent technical performance, the use of irrigationsystems more intelligent PLC control, higher reliability.This design describes the programmable controller (PLC) in the automatic control system ofwater-saving irrigation, irrigation can be classified according to the different types of land. System according to water demand A, B, C are three different types of crops were irrigated using different modes, the system consists of two parts actuators and control bodies, executive agencies aremainly motor as a driving source, by controlling the start and stop of the motors to control thepump to work, giving the crop irrigation. The main control mechanism is programmablecontrollers. In order to reduce the pump motor starting current, to reduce the impact on the gridformation, reduce energy consumption, the system uses Y-? start.KEY WORDS: PLC ; Automatic irrigation; Y-? startII目录目录1 绪论 ..................................................................... .. (1)1.1 课题背景及目的 ..................................................................... .. (1)1.2 课题研究现状 ..................................................................... (1)1.2.1 国外研究现状 ..................................................................... .. (1)1.2.2 国内发展现状 ..................................................................... .. (2)1.3 目的和意义 ..................................................................... . (2)1.3.1 研究目的 ..................................................................... . (2)1.3.2 研究意义 ..................................................................... . (2)2 灌溉系统总体方案 ..................................................................... .. (3)2.1 总体设计 ..................................................................... .. (3)2.1.1 灌溉综述 ..................................................................... . (3)2.1.2 系统主要功能 ..................................................................... .. (3)2.2 系统运行结构图 ..................................................................... .. (3)2.3 系统运行方式 ..................................................................... (4)3 硬件设计 ..................................................................... (5)3.1 系统硬件的设计原则 ..................................................................... (5)3.2 控制器的确定 ..................................................................... (6)3.3 系统的组成 ..................................................................... . (7)3.3.1 设备确定 ..................................................................... . (7)3.3.2 PLC输入/输出点分配...................................................................... . (8)3.3.3 电机启动 ..................................................................... . (9)4 软件设计 ..................................................................... . (11)4.1 设计方法 ..................................................................... (11)4.2 设计原则 ..................................................................... (11)4.3 系统功能的设计 ..................................................................... (12)4.3.1 灌溉流程设计 ..................................................................... (12)4.3.2 电机启动设计 ..................................................................... (20)5 PLC的调试与程序的仿真 ..................................................................... . (21)5.1 PLC控制的安装与布线 ..................................................................... . (21)5.2 程序的仿真 ..................................................................... .. (22)6 结论与展望 ..................................................................... (25)III湖北科技学院学士学位论文致谢 ..................................................................... (27)参考文献 ..................................................................... .. (29)附录 ..................................................................... . (31)IV绪论1 绪论1.1 课题背景及目的我国水资源短缺，利用率低，水浪费严重，供需矛盾突出。

基于风险矩阵的风险评估方法及应用研究

1.2 论文研究内容与技术路线 ........................................................................................... 5 1.2.1 论文研究内容 ..................................................................................................... 5 1.2.2 论文结构安排 ..................................................................................................... 5 1.2.3 论文研究技术路线图 ......................................................................................... 8
Key Words: risk matrix, level of risk, risk assessment, Borda method, AHP (analytic hierarchy process)
II
北京理工大学硕士学位论文
目录
第 1 章绪论 .........................................................................................................1
In this paper, we study in the traditional risk matrix method, fully analyze the principles and steps of this method, and put forward the improved methods of risk hierarchy division and Borda method according to its disadvantages of simply using P × C for the risk hierarchy division. We construct risk hierarchy division model Pα × C β , and analysis the advantages of the improvement. Finally, with Asiainfo-linkage’s P0 project as an example, we apply the improved risk matrix method that based on the risk assessment to the software project risk assessment, and make an instance analysis.This example proves the maneuverability of this paper’s research and help enterprise to understand and implement risk assessment more effectively.tract

MK_17.《纽约适应计划》报告解读

1.3 《计划》中应对气候变化的措施
气候变化将使纽约市不同方面都面临挑战，并对城市中各种活动产生影响。《计划》涉
及不同灾害的应对，重点关注洪水对城市的威胁，对洪灾进行全方位的评估，分别从岸线、
建筑以及重点基础设施这三方面提出了应对气候变化的适应性措施。其中，重点基础设施部
分包括保险、公共设施、能源、医疗、通讯、交通、公园、水资源等多个方面（表 2)。
经济合作与发展组织（OECE)
2009 年
OECD 环境政策委员会与发展援助委员会合作完成《将气候变化纳入发展合作的政策指导》的报告
世界银行
2009 年
发布《发展中国家适应气候变化的成本：新的方法与估计》报告（草）
来源：根据《气候变化与低碳城市规划》一书内容绘制
1 《纽约适应计划》解析
1.1 《计划》基本框架
公停水停电、交通瘫痪、天然气重新设计管理框架
共中断等严重扰乱了居民的正加强现有基础设施应对气候事件的能力
服常生活。飓风给城市经济与生改装管网设施以提高韧性
务活带来了无法估计的损失，在减少能源需求
设未来，频繁的飓风与热浪将给提供多种选择应对设备中断
施城市基础设施带来新的问题
液
加固供应能源的基础设施
纽约适应计划包括了五大部分二十小章节，五大部分分别是简介、气候分析、城市基础
设施及人居环境、社区重建及韧性规划、资金与实施。其中简介包括飓风桑迪及其影响、气
候分析，城市基础设施建设及人居环境又包括海岸带防护、建筑、经济恢复（保险、公用设
施、健康等）、社区防灾及预警（通讯、交通、公园）和环境保护及修复（供水及废水处理等）[3]，社区重建及韧性规划则对纽约五个区分别提出相应的适应对策。

MK 检验ppt课件

E(sk
)
n(n 1) 4
Var(sk
)
n(n
1)(2n 72
5)
3
UFi为标准正态分布，它是按时间序列x顺序x1,x2,…,xn计算出的统计量序列，给定显著性水平α，查正态分布表，若 |UFi|>Ua，则表明序列存在明显的趋势变化。 UB按k=时–U间F序k，列kx=逆n序,n–x1n,,x…n-,11,…)，,xU1B，1再=0重。复上述过程，同时使这一方法的优点在于不仅计算简便，而且可以明确突变开始的时间，并指出突变区域。因此，是一种常用的突变检测方法。计算步骤：
列的突变。给定显著性水平α=0.05，即U0.05=±1.96。计算结果绘成图5.2。
表：1900-1990 年上海年平均气温序列
1900-1909 15.4 14.6 15.8 14.8 15.0 15.1 15.1 15.0 15.2 15.4 1910-1919 14.8 15.0 15.1 14.7 16.0 15.7 15.4 14.5 15.1 15.3 1920-1929 15.5 15.1 15.6 15.1 15.1 14.9 15.5 15.3 15.3 15.4 1930-1939 15.7 15.2 15.5 15.5 15.6 16.1 15.1 16.0 16.0 15.8 1940-1949 16.2 16.2 16.0 15.6 15.9 16.2 16.7 15.8 16.2 15.9 1950-1959 15.8 15.5 15.9 16.8 15.5 15.8 15.0 14.9 15.3 16.0 1960-1969 16.1 16.5 15.5 15.6 16.1 15.6 16.0 15.4 15.5 15.2 1970-1979 15.4 15.6 15.1 15.8 15.5 16.0 15.2 15.8 16.2 16.2 1980-1989 15.2 15.7 16.0 16.0 15.7 15.9 15.7 16.7 15.3 16.1

mk趋势检验

mk趋势检验
MK趋势检验（Mann-Kendall test）是一种常用的非参数检验方法，用于检验一组数据是否存在趋势性的变化。

MK趋势检验不对数据的概率分布进行假设，适用于任何连续的数据集。

MK趋势检验的原假设为：数据集中的观测值是独立的，并且没有趋势性的变化。

备择假设为存在趋势性的变化。

MK趋势检验的基本思想是对数据集中的所有观测值进行两两比较，统计出逆序对的数量。

如果逆序对的数量明显大于或明显小于预期值，则可以拒绝原假设，认为数据集中存在趋势性的变化。

具体的MK趋势检验步骤如下：
1. 将数据集中的每个观测值与其他所有观测值进行比较，计算逆序对的数量。

2. 根据逆序对的数量，计算出统计量Z：
Z = (S - E[S]) / sqrt(Var[S])
其中，S为逆序对的数量，E[S]为逆序对的期望值，Var[S]为逆序对的方差。

3. 根据样本大小n，计算出标准正态分布的临界值Zα/2，α为显著性水平。

4. 如果Z的绝对值大于Zα/2，则可以拒绝原假设，认为数据集中存在趋势性的变化。

MK趋势检验的优点是适用于各种类型的数据集，并且不对数
据的概率分布进行假设。

然而，MK趋势检验也存在一些限制，例如对数据集大小的要求较高，且对异常值比较敏感。

总之，MK趋势检验是一种常用的非参数检验方法，用于检验
一组数据是否存在趋势性的变化。

通过计算逆序对的数量，并将其与预期值进行比较，可以判断数据集中是否存在趋势性的变化。

偏见理论综述

2 文献综述
2.1 偏见的定义
偏见是人们以不正确或不充分的信息为根据而形成的对其他人或群体的片面的甚至错误的看法。对一个团体持有偏见的人倾向于忽视该团体成员个人的品质，而在对该团体的负面评价的基础上对他们做出预先判断。1越来越多的研究者认为，即使在对其毫无知觉的基础之上我们也会产生偏见。（Brendl et al.2001;Dovidio, 2001）因此，偏见可以分为外显偏见和内隐偏见，外显偏见是有意识持有的偏见，内隐偏见是无意识持有的偏见。偏见和态度Байду номын сангаас关但又不同于态度，偏见是一种负面的态度。态度包含三个成分：认知，情感和行为倾向。与态度的认知成分相对应的是刻板印象(Sterotype)，代表着人们对其他团体的成员持有的共有信念，指的是对人的一种固定的思维方式，不考虑任何个体的变异。刻板印象有可能是由正面特征组成，但是当对一些社会团体的刻板印象是比较消极的特征时，这些刻板印象可能会成为偏见及歧视的基础。偏见是与情感要素相联系的倾向性，它对他人的评价建立在其所属的团体之上，而不是认识上。从这一点来看，偏见既不合逻辑也不合情理。行为成分
2.2.1.1 团队冲突的起因
分配资源：组织在分配资源时，总是按照各个团队的工作性质、岗位职责、在组织中的地位以及组织目标等因素分配资金、人力、设备、时间等资源，不会绝对公平。各类团队在成员数量、权力大致相同的情况下，会为了组织内有限的预算、空间、人力资源、辅助服务等资源而展开竞争，产生冲突。例如，企业里生产部门与销售部门的冲突；大学里院与院、系与系之间为争取经费、设备、奖励名额等发生冲突。另外，团队之间可能会共用一些组织资源，但是在具体使用过程中会出现谁先谁后、谁多谁少的矛盾。团体目标：每一个团队都有自己的目标，而这些目标都是为了实现组织的目标，因此，每个团队都需要其他团队的协作。比如，市场营销部门要实现营销目标，就必须得到生产部门、财务部门、人事部门、研发部门的配合与支持。但现实情况是，各个团队的目标经常发生冲突。例如，营销部门的目标是吸引客户，培养客户忠诚，这就要求生产部门生产出质优价廉的商品。而生产部门的目标是降低成本，减少开支，以尽可能少的资源生产尽可能多的商品，而这就不能保证商品质量。因此，营销部门与生产部门就可能发生目标冲突。相互依赖性：相互依赖性包括团队之间在前后相继、上下相连的环节上，一方的工作不当会造成另一方工作的不便、延滞，或者一方的工作质量影响到另一方的工作质量和绩效。组织内的团队之间都是相互依赖的，不存在完全独立的团队。相互依赖的团队之间在目标、优先性、人力资源方面越是多样化，越容易产生冲突。例如，生产部门希望采购部门尽可能增加存货，以便在生产需要时能及

csr,共同规范目录

竭诚为您提供优质文档/双击可除csr,共同规范目录篇一：csra创新助手报告——主题分析报告创新助手平台提供北京万方软件股份有限公司20xx-07-11报告目录报告核心要素................................................. ................................................... .. (i)一、主题简介................................................. ................................................... . (1)二、主题相关科研产出总体分析................................................. (1)2.1文献总体产出统计................................................. . (1)2.2学术关注趋势分析................................................. . (2)三、主题相关科技论文产出分析................................................. .. (2)3.1中文期刊论文................................................. (2)3.1.1近十年中文期刊论文分布列表 (2)3.1.2中文期刊论文增长趋势................................................. (3)3.1.3发文较多期刊................................................. . (4)3.1.4发文较多的机构................................................. (4)3.1.5发文较多的人物................................................. (5)3.1.6核心期刊分布数量对比................................................. (5)3.1.7最近相关中文期刊论文................................................. . (5)3.1.8被引较多的相关期刊论文................................................. (6)3.2学位论文................................................. .. (7)3.2.1近十年学位论文年代分布列表 (7)3.2.2学位论文增长趋势................................................. .. (8)3.2.3硕博学位论文数量对比................................................. (9)3.2.4发文较多的机构................................................. (9)3.2.5发文较多的人物................................................. (9)3.2.6最近相关学位论文................................................. (10)3.3中文会议论文................................................. . (10)3.3.1近十年中文会议论文年代分布列表 (10)3.3.2中文会议论文增长趋势................................................. . (11)3.3.3中文会议论文主办单位分布................................................. ..123.3.4发文较多的机构................................................. . (12)3.3.5发文较多的人物................................................. .. (13)3.3.6最近相关中文会议论文................................................. .. (13)3.4外文期刊论文................................................. . (13)3.4.1近十年外文期刊论文年代分布列表 (13)3.4.2外文期刊论文增长趋势................................................. . (14)3.4.3最近相关外文期刊论文................................................. (14)3.5外文会议论文................................................. .. (15i)篇二：ich指导原则文件目录(中英文)人用药品注册技术要求国际协调会（ich）文件目录ich 的论题主要分为四类，因此ich根据论题的类别不同而进行相应的编码分类：1.“q”类论题：q代表quality，指那些与化工和医药，质量保证方面的相关的论题。

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MK_17.《纽约适应计划》报告解读

MK 检验ppt课件

mk趋势检验

偏见理论综述

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