郑州—西安客运专线无线闭塞中心系统分析

列车运行控制系统的目的是保证列车安全可靠和高效率运行。传统的列车运行控制系统是以车站联锁设备为核心,由车站联锁设备检查从调度中心发出的控制命令是否正确,然后选路,最终由司机确认地面信号,发出行车命令。但随着列车速度的提高,极易造成对地面信号的误认,而且基于轨道电路的信息传输已不能满足高速列车对安全性的要求,而基于通信的无线传输列车运行控制系统则能满足。无线闭塞中心系统RBC是基于通信的列车运行控制系统的地面核心部分。介绍了郑西客运专线RBC系统,分析了系统的应用背景和特点。详细叙述了系统的功能、结构组成,并且对接口部分从内部和外部两方面进行了介绍。     

Agricultural technology adoption and household welfare: Measurement and evidence

Previous studies on the adoption and impacts of improved crop varieties have relied on self-reported adoption status of the surveyed households. However, in the presence of weak variety maintenance and poorly functioning seed certification system, measurement errors in self-reported adoption status can be considerable. This paper investigates how such measurement errors can lead to biased welfare estimates. Using DNA-fingerprinting based varietal identification as a benchmark, we find that misclassification in self-reported adoption status is considerable, with significant false negative and positive response rates. We empirically show that such measurement errors lead to welfare estimates that are biased towards zero and substantially understate the poverty reduction effects of adoption. While the empirical evidence suggests attenuation bias, our theoretical exposition and simulations demonstrate that upward bias and sign reversal effects are also possible. The results point to the need for improved monitoring of the diffusion process of improved varieties through innovative adoption data collection approaches to generate robust evidence for prioritizing and justifying investments in agricultural research and extension.     

The use of ranking formulae in R & D projects

Abstract . Numerous ranking formulae have been proposed in the literature for use in the evaluation and selection of R& D projects, but their rate of adoption has been relatively slow. This situation appears to be changing in the U.K. and a considerable amount of effort is being expended to improve the methods of obtaining estimates for the variables which appear in the formulae. This paper argues that the most commonly quoted formulae do not adequately represent the practical situation and are likely to introduce bias into the system as well as tending to make estimating more difficult. A modified ranking index derived from a decision tree type of analysis is suggested as a more useful estimate of the worth of a project, but it is concluded that any such formulae will always have serious limitations because they must inevitably ignore important characteristics of the research process.     

生产者延伸责任制度研究

生产者延伸责任（Extended Producer Responsibility，简称EPR）制度是发展循环经济．建设资源节约型和环境友好型社会的基本的法律制度。EPR制度是将传统生产者责任延伸至产品全生命周期．明确了产品失效报废后回收利用和再资源化的责任主体。本文分析EPR制度概念形成及其内涵．探讨了EPR制度学理依据与现实考量，对国外EPR制度的实施对象、回收模式、付费方式进行了系统研究，并结合我国现状分析了我国实施EPR制度的紧迫性。     

基于ARM和μC/OS-Ⅱ的嵌入式电机测试系统的设计

针对传统的电机测试系统逻辑运算能力有限及性能不稳定的问题,提出了一种基于ARM和μC/OS-Ⅱ的嵌入式电机测试系统的设计,详细介绍了以高性能ARM微处理器S3C2410X为核心的硬件电路及嵌入式操作系统μC/OS-Ⅱ在S3C2410X上的移植。该系统能够对电机的电压、电流、转速等参数进行实时采集,可以提高测试系统的稳定性和实时性。     

“模糊+PI”控制技术在开关磁阻电动机调速系统中的应用

着重研究“模糊 +PI”控制技术在开关磁阻电动机调速系统中的具体应用 ,对解决开关磁阻电动机调速系统的显著非线性问题 ,提高开关磁阻电动机调速系统动态特性做了探讨 ,为开关磁阻调速电动机向更宽、更广的应用领域发展提出了自己的见解 ,以供进一步研究开关磁阻电动机调速系统参考。     

European Integration and Transnational Management-Union Relations in the Enterprise

The Single European Market has generated considerable interest in the prospects for European-level management-union arrangements in transnational companies. European works councils have emerged in a small but growing number of transnationals. The circumstances in which companies might promote such arrangements are analysed. Attention is paid to whether companies are organized along international product or territorial lines and to their product diversification strategies. Transnationals will also be influenced by trade union pressure at European level and by aspects of the industrial relations system in their home country.     

全自动生化分析仪机电机构研究

介绍了一种以单片机为控制核心、步进电机与直流电机为执行机构、TA8435H作为步进电机驱动芯片的全自动生化分析仪,其实现了托盘旋转、吸排系统升降和旋转等功能,具有定位准确、自动化程度高等特点。     

The Statutory Union Recognition Procedure in the Employment Relations Bill: A Comparative Analysis

This paper analyses the provisions for union recognition contained in the British Employment Relations Bill in the light of problems with the system in operation in the 1970s and with its US counterpart. First, it establishes that these problems may be attributable largely to defects in design rather than fundamental flaws, and that this is demonstrated by the relative success of the Canadian system. Second, the paper evaluates the Bill's provisions, finding that it avoids many weaknesses of the 1970s and US systems but lacks a number of the Canadian system's strengths. Consequently recognition may be readily attainable if the union already has a majority, but there could be undue delays and opportunities for employer interference if this is not the case, and in general union recognition may not translate into effective collective bargaining. However, if the provisions do help diffuse the partnership model as the government envisages, apparent weaknesses in the Bill may yet prove to be the hallmarks of a distinctive system.     

An Asymmetric Oligopolist can Improve Welfare by Raising Price

We demonstrate that, in Bertrand/Cournot equilibrium, a firm with a relatively small market share may improve social welfare by raising its price. This could be because the price increase can mitigate an output-structure distortion: if there are two goods which have the same marginal cost, then, under some conditions, the good in higher demand (the efficient good) will have a higher markup rate than the other good (the inefficient good). This suggests that the output structure is distorted in favor of the inefficient good, since the higher markup rate of the efficient good should lead to a considerable increase in demand for the inefficient good.     

System supplier's customer strategy

The article addresses the management of dynamic customer relationships in large-scale, complex system business. It combines the existing knowledge on system business, high-tech services and buyer-seller relationships with an international multiple case study. As a result, we produce a framework model, which provides the answers to the following critical questions: What are the key activities through which a system supplier provides value for the customer? What are the system supplier's roles for the customer? How does the customer's strategy and capabilities influence the customer's need for the supplier's activities and its evaluation of potential suppliers? And, how does the stage of the supplier-customer relationship and the system's technology cycle influence the customer's perceived need for the supplier's activities? In sum, the framework model provides a major theoretical contribution to more profoundly understand and manage complex system supplier-customer relationships.     

Viewpoint: Climate impacts on agriculture: Searching for keys under the streetlight

This paper provides a critical assessment of the literature estimating the consequences of climate impacts in agriculture and the food system. This literature focuses overwhelmingly on the impact of elevated CO2 concentrations in the atmosphere, higher temperatures and changing precipitation on staple crop yields. While critically important for food security, we argue that researchers have gravitated to measuring impacts ‘under the streetlight’ where data and models are plentiful. We argue that prior work has largely neglected the vast majority of potential economic impacts of climate change on agriculture. A broader view must extend the impacts analysis to inputs beyond land, including the consequences of climate change for labor productivity, as well as for purchased intermediate inputs. Largely overlooked is the impact of climate change on the rate of total factor productivity growth and the potential for more rapid depreciation of the underlying knowledge capital underpinning this key driver of agricultural output growth. This broader view must also focus more attention on non-staple crops, which, while less important from a caloric point of view, are critically important in redressing current micronutrient deficiencies in many diets around the world. The paper closes with numerical simulations that demonstrate the extent to which limited input and output coverage of climate impacts can lead to considerable underestimation of the consequences for food security and economic welfare. Of particular significance is the finding that humans in the humid tropics are likely more vulnerable to heat stress than are many of the well-adapted crops, such as rice. By omitting the impact of heat stress on humans, most studies of climate impacts greatly understate the welfare losses in the world’s poorest economies.     

跨组织信息系统研究述评

分工与合作越密切的组织,信息分享需求越高,因此．越需要重视跨组织的信息整合。今天,跨组织信息系统已成为企业获取竞争优势的一种战略需要。文章讨论了跨组织信息系统的定义、研究跨组织信息系统的理论视角和创建跨组织信息系统的意义,并进行了述评。     

PROJECT JUSTIFICATION IN A MULTIPRODUCT CHEMICAL PLANT∗

In addition to measurable economic consequence of an alternative investment decision, there are other important prospective consequences which cannot readily be reduced to a single common denominator stated in money terms. The extant literature of engineering economy almost entirely avoids discussion of the considerable problems which arise when attempts are made to include “irreducibles” formally in analysis, although some progress has been made in recent years in other academic disciplines. This paper, based upon some earlier work for the United States Navy, suggests a technique which can be used to include “irreducibles” along with monetary data in determining relative desirability of mutually exclusive alternative proposals. The logic of the problem and the formal structure of a desirable solution are discussed.     

From Experience: New Idea Enhancement at Amoco Chemical: An Early Report from a New System

Amoco Chemical Company operates the New Ideas Process (NIPr) as its innovation support system for employee ideas generated outside formal business development channels. The system's goal is to operate a process that involves employees in the identification and initial development of ideas for new business opportunities for the company. Jeff Felberg and David DeMarco describe NIPr's basic philosophy, procedures, organization, and staffing. Additionally, they provide quantitative and qualitative results from the first four years of the system's operation for the areas of employee involvement, business concept development, production of funded ideas, and cultural enrichment of the company.     

Developing an expert system on project evaluation: Pt II: Structuring the system

The work here described is the early stages of a programme to develop a series of Expert Systems (ES's) in the management of R&D. In particular, the development of a prototype ES using a package program Crystal Ver. 2.1 is the focus together with the problems encountered. The literature had suggested that the use of such packages facilitated the process for those exploring ES's. What was not clear from the literature or the program manuals was the limited range of problems which could be handled. The programs have a rigid structure such that unless the logic of the problem solving process matches that of the program, severe difficulties will ensue. This paper outlines the inherent structure of the programs and indicates the kind of problems which would fit. Specific problems which were encountered when trying to stretch the use of the program are explained in detail. It goes on to explain how these problems were got round using Lotus 1–2–3 which proved far more flexible in practice. This kind of understanding is essential if ES's are to become every-day tools of R&D management. The objective in developing the Expert System (ES) was for it to be advisory to those preparing project proposals for possible submission to higher management within the context of an R&D laboratory. Thus the intention was to capture the expertise of senior managers, make it available to more junior ones, and thereby improve the quality of their work. This concept proved to be naive in that the expertise proved to be so diffuse that a wholly new rationale to structure the expertise had to be developed. This process, the subsequent development into a prototype ES, and its evaluation, have already been published (Wilkinson, 1991). The literature on ES's had suggested that the use of available package programs was straight forward and that the real problem was in establishing the expertise to be used and in structuring it to fit the program. This too proved to be an over-simplification. When this work started, the exact nature of the package programs had not been spelt out adequately. The purpose of this paper, Part II, is to describe their inherent structure and the limitations which this imposes on the kind of problems for which they can be used. The insights gained in this work into the evaluation of projects and the inadequacies of previous evaluation techniques will form the contents of Part III of this series of papers.     

Reviewing the intellectual structure of product modularization: Toward a common view and future research agenda

Product modularization in new product development has attracted considerable interest among scholars and practitioners from diverse fields of specialization. This has resulted in cross-disciplinary diversity in the field, diverting attention from its overall intellectual structure and hindering the development of a common view and shared concepts. Extant research lacks an integrative review, transcending a focal discipline that could identify gaps and ambiguities while making recommendations to advance the field. Considering a period of 30 years (1990–2020), we generate a data set of 2988 citing publications to which we apply a co-citation analysis. Thereby, we uncover the intellectual structure of the field and find three research perspectives that represent key knowledge bases: (1) product system, (2) production system, and (3) organizational system. Delimiting the data set into four periods, we can track developments over time, where we notice an increasing disintegration of the product system perspective, which is rooted in the discipline of engineering design. Within the two other perspectives, we document extensive dynamism in terms of publications, especially in the two most recent periods, indicating an active discussion and a potential receptivity to new trends. For these periods, we also identify an emerging cluster of fundamental publications and an increasing emphasis on the concept of system architecture. Leveraging the synthesis of these results, we forge links between neighboring disciplines and recommend avenues for further research, ideally to develop a more common view.     

基于TOC的管理信息系统需求优先级研究

在管理信息系统规划与开发过程中,合理优化需求并确定需求优先级对系统的成败具有重要的作用。本研究提出基于TOC的需求优先级评估方法。该方法通过分析需求背后的管理目标、措施以及在实现过程中可能面临的约束,对需求进行优化和排序,选择价值及可行性较高的需求进行优先开发,最终达到提升管理信息系统开发效益的目标。     

Clientele Effects on the Demand For Housing Price Appreciation

If house buyers are segmented by income, one might expect to observe buyers in such markets valuing the benefits of expected capital gain differently. Presumably, individuals experiencing higher marginal tax rates should be inclined to pay relatively more for anticipated capital gain since the opportunities of sheltering such income from taxation are greater. This paper attempts to identify a proxy for expected capital gain by using the hedonic price methodology to predict a recent price series for each housing unit in a sample of sales. That proxy is then used to determine an individual buyer's marginal willingness to pay for anticipated price appreciation. The results indicate that one cannot reject the joint hypothesis that homebuyers naively extrapolate from prior implied price performance to establish future price expectations and the variation in willingness to pay for that expectation may be a function of the buyer's income. This suggests the existence in housing markets of a phenomenon termed the clientele effect. This effect has been the subject of considerable examination in the finance literature.     

Spectrum sharing in the gray space

There has been considerable effort to let more wireless devices operate in white space spectrum, that is within frequency bands and geographic areas where no wireless devices are active. Making white space available is certainly useful, but there are other sharing opportunities as well, some of which have been obscured by dangerous misconceptions about the concept of unused spectrum. This paper discusses allowing more devices to operate safely in gray space spectrum, that is spectrum that is actively being used in that transmissions are underway—something many economic models assume is impossible. The paper focuses on primary–secondary sharing, so devices gaining access to spectrum operate on a secondary basis in a way that never causes harmful interference to primary systems. Examples of primary–secondary gray space sharing mechanisms are described in which devices are allowed to share spectrum with broadcasting, radar, and cellular systems. Quantitative analysis shows that it is technically possible to support significant communications among secondary devices in spectrum that is already heavily used by cellular or radar. However, gray space sharing generally causes primary and secondary systems to be more technically interdependent than white space sharing, so different policy and governance structures are needed. Secondary market rules can support gray space sharing in cases where there is a single primary spectrum user, such as a cellular carrier. In cases where technology is static, the regulator may be able to control access for secondary devices. However, in cases with multiple primary users and multiple secondary users of spectrum, as might be seen in bands with radar for example, a new kind of governance body will be needed to facilitate spectrum sharing.