不确定性条件下的设备替换优化的 随机动态规划方法

本文提出了一种解决设备更新换代优化（ERO）问题的随机动态规划（SDP）模 型,用以明确地解释在车辆利用中的不确定性,并采用 Bellman 算法解决 ERO SDP 问题. 针对 SDP 状态空间的增长,提出了特殊简化算法,以解决动态规划方法中固有的“维数 灾”问题,确保所需的内存和计算时间不会随着时间范围的增加而成倍增长.并对 SDP 软 件的实现技术、功能和图形用户界面（GUI）进行了讨论,开发了基于 SDP 的 ERO 软件, 并使用美国得克萨斯交通局（TxDOT）现有车辆数据进行验证.对统计结果、软件计算时 间和求解效果进行综合分析,结果显示,使用该 ERO 软件,估计大量成本可以节省.     

Economic value of natural Coastal wetlands: A critique

Recent estimates by J. Gosselink, E. Odum, and R. Pope of the economic value of natural wetlands have had considerable impact on analyses and discussions of public policies concerning natural wetlands management. However, these economic value estimates are neither conceptually nor empirically correct. First, these workers failed to recognize the nature of the process by which economic values are determined and made an illegitimate marriage of the principles of systems ecology and economic theory. Second, where Gosselink et al. attempted to apply proper economic principles, their calculations resulted in economic value estimates that are most likely in error.     

National policy towards cars: Singapore

Singapore has experienced rapid growth in car ownership, and private transport accounts for just under half of motorized trips in Singapore. Yet only since 1970 have determined efforts been made to curtail this increase. Simultaneously with this growth, Singapore's land‐use planners had called for the diversion of population growth into outlying residential estates while maintaining the central area's importance as an employment centre. The resulting anticipated concentration of commuter movement suggested a need for controls to restrain car ownership, reduce central‐area congestion and divert road users on to public transport. The policies followed are described. Those against ownership have included heavy road taxes and registration fees, with a system of discounts on the latter to discourage new purchasers except when replacing scrapped cars. Policies against car use include fuel taxes and the Area Licensing Scheme in the city centre, while parking space is also closely regulated. The measures adopted imply a goal of efficiency in promoting Singapore's planning objectives rather than environmental, safety or equity considerations, although the first two of these have lately received much more attention than formerly. The policies’ effect has been a temporary reversal in the growth of car ownership, but this growth has since resumed and recent further fee increases suggest a panic reaction rather than a coordinated strategy. Such coordination appears at present to be hampered by the fragmented administration of matters relating to transport. Other measures relating to car ownership and use in Singapore are also described.     

Evaluating airlines with slack‐based measures and meta‐frontiers

This study develops a new performance evaluation model, called the meta dynamic network slack‐based measure (MDN‐SBM). This model incorporates the concept of meta‐frontiers to facilitate comparisons of performance of decision making units, while at the same time it generalizes the slack‐based measure (SBM), network SBM, and dynamic SBM. This MDN‐SBM model is capable of dealing with two important special features of the transportation industry: unfavorable accidents and non‐storable goods, i.e. available seat‐kilometers that are wasting assets that lose value completely if unsold before departure. Hence, this generalized model contains higher differentiable capability than all its SBM‐related submodels in the literature. To demonstrate, 35 international airlines with two divisions (production and consumption) in three terms (one‐year time periods from 2007 to 2009) have been analyzed using meta‐performance efficiency measures (ME) for all decision making units and have also been compared by geographical area (Asia‐Pacific, N. America/Europe). The numerical example and comparison validate the proposed MDN‐SBM model and suggest the airlines should put more focus on input resources reduction for productivity improvement. Copyright © 2016 John Wiley & Sons, Ltd.     

Logistics opportunities in Asia and development in Taiwan

The economy in Asia is growing rapidly. As a consequence, transportation and communication technologies and the changing needs of customers and shippers have resulted in Asian and Taiwan's logistics being in transition. This paper discusses why logistics changes, and explores the opportunities for Asian logistics development. The issues of logistics perspectives of private sectors in Taiwan are then raised. Finally, logistics development in Taiwan is described.     

Developing management guidelines for oil and gas activities: The louisiana experience

Abstract

Preliminary management guidelines have been derived for oil and gas activities in coastal Louisiana. Derivation of these guidelines was done in terms of the natural function of the coastal ecosystem; this means that all economic activities should be designed to complement natural function as much as possible. The guidelines range in scope from very specific, almost performance standards, to very general admonitions. For example, we have suggested that spoil banks, produced as a result of dredging, should not be higher than the height of the daily tide or roughly 15 cm in coastal Louisiana, and at the other extreme, we have suggested that all dredging should be done with great care during wildlife migrations, spawning, and nesting times.     

On measuring the efficiency of public enterprises: Bus operating companies in the San Francisco Bay area

It is important to be able to say whether or not an enterprise in the public sector is efficient and to measure this aspect of its performance. Public enterprises sometimes have legitimate reason to treat efficiency as secondary, but they also may resist efficiency measurement for other reasons.Statistical cost functions containing experience from similar enterprises provide useful yardsticks for public administrators. A purported cost function can be inadequate, however, as is shown in one example.Statistical cost functions allow comparison of bus properties by giving a range within which costs of an efficient property should fall. While random influences cannot be excluded, if observed costs fall outside two standard errors of prediction, there is a good case to say the property is inefficient. The usefulness of the standard error of prediciton as a measure of precision is explored.Nationally estimated cost functions were used to investigate the bus operations only of three San Francisco companies. Two were found within sampling error, one was significantly more costly on its motorbus operations than average experience in the nation. A closer look would then be in order by those funding this property. Several years' experience is explored showing changes over time as well as across companies.This material was prepared with the support of National Science Foundation Grant No. GI-37181 to the University of California. The results and views are the independent product of university research and are not necessarily concurred in by the National Science Foundation. The Institute of Urban and Regional Development at U.C. Berkeley facilitated research herein.     

Nutrient Assimilation Services for Water Quality Credit Trading Programs: A Comparative Analysis with Nonpoint Source Credits

Water quality trading programs allow regulated point sources to meet some nutrient control requirements by buying nutrient reduction credits from other pollutant sources. Reduction credits can be created when agricultural land managers implement best management practices and regulators predict that those practices will result in water quality conditions equivalent to controlling discharges at the regulated source. However, natural variability in runoff combines with model and data limitations to make predictions of water quality equivalence uncertain. Nutrient assimilation credits can be created by increasing the capacity of the ecosystem to assimilate nutrients through investments in aquatic plant biomass creation and harvest, shellfish aquaculture, stream restoration, and wetlands restoration and creation. Nutrient assimilation credits and agricultural nonpoint source reduction credits are evaluated based on a number of water quality criteria including service quantification certainty, temporal matching, additionality, and leakage. Nutrient assimilation credits can provide greater certainty than agricultural best management practices in producing equivalent water quality outcomes and should be an option in trading programs.