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951.
An assessment of railway capacity 总被引:2,自引:1,他引:1
M. Abril F. Barber L. Ingolotti M.A. Salido P. Tormos A. Lova 《Transportation Research Part E: Logistics and Transportation Review》2008,44(5):774-806
In this paper, we review the main concepts and methods to perform capacity analyses, and we present an automated tool that is able to perform several capacity analyses. Capacity is extremely dependent on infrastructure, traffic, and operating parameters. Therefore, an in-depth study of the main factors that influence railway capacity is performed on several Spanish railway infrastructures. The results show how the capacity varies according to factors such as train speed, commercial stops, train heterogeneity, distance between railway signals, and timetable robustness. 相似文献
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Limits to forecasting in personalized medicine: An overview 总被引:1,自引:1,他引:0
Biomedical research is generating massive amounts of information about potential prognostic factors for health and disease. However, few prognostic factors or systems are robustly validated, and still fewer have made a convincing difference in health outcomes or in prolonging life expectancy. For most diseases and outcomes, a considerable component of the prognostic variance remains unknown, and may remain so for the foreseeable future. I discuss here some of the main problems in medical forecasting that pose obstacles to personalized medicine. Their recognition may help identify solutions to improve personalized prognosis, or at least understand and cope with the component of the future that we cannot predict. Much prognostic research is stuck at generating “publishable units”, without any interest in conclusively proving their worth, let alone moving them into real life applications. Information is reported selectively and reporting is deficient. The replication record of prognostic claims is poor. Even among replicated prognostic effects, few are convincingly shown to add much information besides what is already known through more simple, traditional measurements. There are few efforts to systematize prognostic knowledge. Most prognostic effects are subtle when traced to the molecular level, where most current research operates. Many researchers, clinicians, and the public are not appropriately educated to interpret prognostic information. We still have not even agreed on what the important health outcomes are that we want to predict and intervene for, and some subjectivity may be unavoidable. Finally, without concomitant effective, affordable, and non-harmful interventions, prognosis alone is of questionable value, and wrong prognosis or a wrong interpretation thereof can be harmful. The identification of these problems also suggests a roadmap on what could be done to amend them. Solutions include a systematic approach to the design, conduct, reporting, replication, and clinical translation of prognostic research; as well as the education of researchers, clinicians, and the general public. Finally, we need to recognize that perfect individualized health forecasting is not a realistic target in the foreseeable future, and we have to live with considerable residual uncertainty. 相似文献
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Manuel?Frondel Peter?Gr?sche Christoph?M.?Schmidt RWI Essen und Ruhr-Universit?t Bochum 《能源经济杂志》2008,32(2):97-101
Home renovation is generally asserted to be a highly effective means to increase residential energy efficiency and thereby contribute to climate protection from reduced energy consumption. As part of a larger package of measures in the residential sector, the German government is consequently providing financial support for home audits from recognized energy experts who provide advice on retrofitting options. To date, the question concerning the effectiveness these home audits has largely escaped empirical scrutiny. The present paper fills this void by providing evidence for considerable free-rider effects within the home audit program, yielding serious reservations with respect to both the effectiveness of the program and its fiscal costs. Moreover, given the substantial differences between the gross- and net effects of home audits that are revealed by this analysis, the program’s contribution to climate protection and thereby the central justification for the associated government outlays is called into question. The social benefit of the program emerges only from those retrofits that would not have been undertaken in the absence of the home audit. 相似文献
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Research in Motion's (RIM's) entry into the Chinese market during a time when many distractions —principally a patent dispute with NTP—occupied management's attention was not a foregone conclusion. China remained a difficult market to crack. One holdup was an impasse with regard to RIM's use of encryption technology and the Chinese authorities' desire to monitor e‐mail traffic and content. Here the technical and political concerns were entangled. To further complicate things, the entirety of RIM had until recently been preoccupied with the legal settlement with NTP in the United States. Issues in this study highlight real‐world dilemmas in a thriving firm. The founders are still in charge, and new markets present themselves regularly. A very real challenge is divided attentions. The standstill over market entry calls for integrative thinking—bringing together disparate and contradictory elements for resolution. RIM's way out will invariably involve embracing complex relationships in order to find a resolution to the various conflicting institutional forces. © 2008 Wiley Periodicals, Inc. 相似文献
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Firms increasingly enter into alliances when expanding into international markets and market segments. Unfortunately, many of these alliances fail because managers are overconfident and unprepared for the diverse and complex contingencies they encounter. Growing research suggests that developing an alliance capability function improves alliance performance. We first identify common types of problems and opportunities that arise from alliance design to alliance dissolution. With this understanding, we then specify the alliance capabilities that must be developed to deal with these contingencies. © 2008 Wiley Periodicals, Inc. 相似文献
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