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941.
In this paper, we present results regarding the experimental validation of connected automated vehicle design. In order for a connected automated vehicle to integrate well with human-dominated traffic, we propose a class of connected cruise control algorithms with feedback structure originated from human driving behavior. We test the connected cruise controllers using real vehicles under several driving scenarios while utilizing beyond-line-of-sight motion information obtained from neighboring human-driven vehicles via vehicle-to-everything (V2X) communication. We experimentally show that the design is robust against variations in human behavior as well as changes in the topology of the communication network. We demonstrate that both safety and energy efficiency can be significantly improved for the connected automated vehicle as well as for the neighboring human-driven vehicles and that the connected automated vehicle may bring additional societal benefits by mitigating traffic waves. 相似文献
942.
Shih-Liang Chao 《Maritime Policy and Management》2017,44(4):496-511
In this study, we establish a multi-stage data envelopment analysis model to evaluate the efficiency of global liner shipping companies (LSCs). Because conventional solution procedures cannot guarantee the uniqueness of solutions, in this study, we specifically devise a new two-phase algorithm to overcome this problem. The first phase ranks the priority of all stages by applying fuzzy analytical hierarchical process. The second phase then solves the efficiency score for each stage according to its priority. We established and empirically tested a three-stage research model based on data collected from the Containerization International Year Book, the Alphaliner website and annual LSC reports for the year 2012. The results show that the proposed algorithm not only determines unique solutions for the efficiency scores but also determines the priority order of the stages involved in this process. Taking advantage of the proposed model and algorithm, LSCs can effectively locate bottlenecks in their production processes and further improve them by adjusting the values of the corresponding input and output variables. In addition, the priority order of the stages obtained from the empirical study can also help LSCs allocate their resources. 相似文献
943.
This paper focuses on the performance of Norwegian bus companies subsidized by the government. The performance is evaluated from a productive efficiency point of view. The framework is that of a deterministic non-parametric Data Envelopment Analysis (DEA) approach to efficiency measurement. In this context several important issues are addressed: efficiency rankings, distribution and scale properties in the bus industry, potentials for efficiency improvements in the sector, the impact of ownership, area of operation and scope, and ways of improving efficiency in the sector. The findings show that the average bus company exhibits increasing return to scale in production of its services. The extent of such returns however vary, with size and is more prevalent among smaller companies. The average bus company is found to have a considerable input saving potential of about 28 percent. Neither economies of scope nor company ownership are found to have an influence on company performance. It is suggested that geographical factors need a closer attention in future research. The implications of DEA results are discussed and concluding remarks offered. 相似文献
944.
A new procedure for generating optimal transport strategies has been applied in nine European cities. A public sector objective
function which reflects concerns over efficiency, environmental impact, finance and sustainability is specified and a set
of policy measures with acceptable ranges on each, identified. Optimal strategies based on combinations of these policy measures
which generate the optimal value of the objective function, are identified, and compared between cities. Resulting policy
recommendations are presented. The results demonstrate the importance of an integrated approach to transport strategy formulation.
They emphasise the role of changes in public transport service levels and of fares, and of charges for car use. By contrast,
new infrastructure projects are less frequently justified. In the majority of cities the revenues from car use charges are
sufficient to finance other elements in the strategy. However, private sector involvement either in initial financing or in
operation may be desirable. Revised objective functions to reflect private sector involvement are specified, and optimal strategies
with private sector operation of public transport are also identified. The requirement to meet private sector rates of return
for public transport operation typically results in lower frequencies and higher fares; charges for car use then need to be
raised to satisfy public policy objectives, but system performance is reduced.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
945.
946.
张运华 《江苏科技大学学报(社会科学版)》2007,21(4):91-94
利用数据包络分析方法,对2002年~2004年各地区船舶生产技术效率及其变动进行了实证分析。得出的结论主要有:历年来河北、辽宁、上海及贵州等地区均表现出了较高的技术效率,同时绝大部分地区船舶生产处于规模报酬递增的阶段;船舶生产规模和其技术效率之间存在正的相关关系;若干地区存在船台及船坞等资本的过度供给。 相似文献
947.
胡文华 《华东交通大学学报》2007,24(4):67-70
介绍了一类由开关放大电路与线性放大电路复合而成的电压跟随器型电源,分析其构成原理,拓扑结构.理论分析、仿真和实验结果表明它具有高效与优波兼顾的特性,以及适应多类负载(含非线性负载)和抗负载扰动的能力. 相似文献
948.
949.
950.
预制拼装技术是水务结构施工工艺的重要发展趋势,接缝处理是当前预制拼装技术的关键技术难点。超高性能混凝土(UHPC)具有强度高、韧性大、耐久性好等技术优势,成为解决预制拼装结构接缝连接的有效途径。考虑到该技术在水务工程领域应用相对较少,根据实际工程开展了相关的研究。首先,针对UHPC湿接缝在排水结构的适用性问题、临时支撑的快速周转、高温与低温施工等难点进行了分析研究,通过全尺寸UHPC浇筑工艺试验,对施工参数进行了探索,并提出了高温与低温条件下浇筑策略。研究保证了UHPC湿接缝浇筑施工的顺利进行,有效提高了预制拼装施工效率,提升了湿接缝浇筑质量。 相似文献