关联时滞大系统的保性能控制

针对关联项具有N×N个任意未知常时滞的线性连续大系统,采用线性矩阵不等式(LM Is)方法,提出了一种分散的无记忆状态反馈二次保性能控制器的存在条件和设计方法.最后用一个示例说明分散无记忆状态反馈二次保性能控制器的设计方法.     

某轮燃油轻改重对主机影响的对比分析

某轮燃油轻改重费用上得到很大的节约,但机械损耗和工作量也都相应提高,说明对于某种机型燃油的降级使用是有限度的,为了安全管理,必须科学地进行综合考虑.     

To save money or to save time: Intelligent routing design for plug-in hybrid electric vehicle

Electric vehicles (EVs) are promising alternative to conventional vehicles, due to their low fuel cost and low emissions. As a subset of EVs, plug-in hybrid electric vehicles (PHEVs) backup batteries with combustion engines, and thus have a longer traveling range than battery electric vehicles (BEVs). However, the energy cost of a PHEV is higher than a BEV because the gasoline price is higher than the electricity price. Hence, choosing a route with more charging opportunities may result in less fuel cost than the shortest route. Different with the traditional shortest-path and shortest-time routing methods, we propose a new routing choice with the lowest fuel cost for PHEV drivers. Existing algorithms for gasoline vehicles cannot be applied because they never considered the regenerative braking which may result in negative energy consumption on some road segments. Existing algorithms for BEVs are not competent too because PHEVs have two power sources. Thus, even if along the same route, different options of power source will lead to different energy consumption. This paper proposes a cost-optimal algorithm (COA) to deal with the challenges. The proposed algorithm is evaluated using real-world maps and data. The results show that there is a trade-off between traveling cost and time consumed when driving PHEVs. It is also observed that the average detour rate caused by COA is less than 14%. Significantly, the algorithm averagely saves more than 48% energy cost compared to the shortest-time routing.     

Tales on the dark side of the transport infrastructure provision: a systematic literature review of the determinants of cost overruns

ABSTRACT

Cost overruns are an endemic feature of the provision of transport infrastructure worldwide. In recent decades, a considerable amount of studies has been devoted to assessing the magnitude and determinants of cost overruns in the transportation sector. However, the empirical findings are scattered between different strands of literature, ranging from the fields of construction engineering and management to that of applied economics. To shed light on the determinants of cost overruns in the execution of transport infrastructure projects, we conduct a systematic review of the empirical literature on the topic. Of the 945 articles retrieved, 26 articles published between 2000 and 2016 meet our inclusion criteria. For them, we describe the different empirical approaches, we provide a classification of the determinants employed in the analyses and summarise their impact on cost overruns. Finally, we suggest some directions for further research in the field.     

Forecasting demand for high speed rail

It is sometimes argued that standard state-of-practice logit-based models cannot forecast the demand for substantially reduced travel times, for instance due to High Speed Rail (HSR). The present paper investigates this issue by reviewing the literature on travel time elasticities for long distance rail travel and comparing these with elasticities observed when new HSR lines have opened. This paper also validates the Swedish long distance model, Sampers, and its forecast demand for a proposed new HSR, using aggregate data revealing how the air–rail modal split varies with the difference in generalized travel time between rail and air. The Sampers long distance model is also compared to a newly developed model applying Box–Cox transformations. The paper contributes to the empirical literature on long distance travel, long distance elasticities and HSR passenger demand forecasts. Results indicate that the Sampers model is indeed able to predict the demand for HSR reasonably well. The new non-linear model has even better model fit and also slightly higher elasticities.     

基于秘密共享的高效RFID安全协议

文章介绍了基于秘密共享的RFID协议的工作流程,并从用户隐私、位置追踪、数据篡改、重放攻击、相互认证、防伪造、中间人攻击、前向安全性、数据库同步等方面探讨了协议的安全性,同时对比分析了协议的效率及成本。结果表明,该协议具有使用简便、安全性能好、效率高、成本低的优点。     

浅谈公路施工企业标后预算管理

标后预算即施工预算,也就是项目的成本预算,它是项目成本管理的主要依据。主要介绍了公路施工企业标后预算的作用、编制依据、编制方法和管理流程。     

浅析公共交通企业财政补贴机制

优先发展城市公共交通,保障城市公交企业可持续发展,迫切需求研究适合我国国情的城市公交财政补贴测算方法.文章明确了公交企业财政补贴机制的基本依据和原则,合理界定财政补贴的范围、方式和资金来源,建立基于公交企业成本规制的财政补贴机制,为建立政策性亏损补贴机制提供依据.     

Reduction of capacity and projected costs associated with seat belt installation on school buses

This study examines the potential effects the installation of seat belts on school buses would have on the fleet capacity in Alabama and the resulting cost implications. The study also documents the myriad research studies and professional opinions offered on the potential safety effects of equipping school buses with safety restraints/seat belts. Four seat configurations for the school buses were analyzed. The first configuration represents the most common current bus seating configuration without seat belts, 3 seats on each side of the aisle and 12 rows (3/3-12). The physical space required for seat belt hardware may result in a loss of a row of seats and may reduce the number of students seated per row. Thus, three more configurations were studied: loss of a row of seats (3/3-11), loss of one seat per row (3/2-12), and loss of both a row of seats and a seat per row (3/2-11). The capacity for each configuration for each bus using current pupil loads was determined. The costs associated with installation of seat belts, and purchase and operation of new buses were obtained. Should school bus seat belts become mandatory in Alabama, the results obtained in this study can be used by any school system to determine the optimum configuration for their pupils, which will identify the number of additional buses that must be purchased by the school system. This study found that many of the buses that would become overloaded due to seat belt installation and the resultant loss of seating will be carrying only a few excess pupils. Transportation supervisors may be able to handle such overloads by transferring these pupils to other buses or by adjusting their bus routes to minimize purchase of new buses. Additional suggestions for handling bus overloads were offered in the body of this report.     

Imperfect reversibility of air transport demand: Effects of air fare,fuel prices and price transmission

There are recent evidence that air transport demand may not have a perfectly reversible relationship with income and jet fuel prices, as is assumed in most demand models. However, it is not known if the imperfectly reversible effects of jet fuel price are a result of asymmetries in the supply side, i.e., asymmetries in cost pass through from fuel prices to air fare, or of demand side behavioral asymmetries whereby people value gains and losses differently. This paper uses US time series data and decomposes air fare and fuel price into three component series to develop an econometric model of air transport demand that is capable of capturing the potential imperfectly reversible relationships and test for the presence or absence of reversibility. We find that air transport demand shows asymmetry with respect to air fare, indicating potential imperfect reversibility in consumer behavior. We also find evidence of asymmetry and hysteresis in cost pass-through from jet fuel prices to air fare, showing rapid increases in airfare when fuel prices increases but a slower response in the opposite direction.