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351.
John P. Devlin 《Transportation》1972,1(2):197-206
This article deals with the Transportation Study currently nearing completion in Dublin. A feature of this Study was the use of simplified data collection and modelling techniques. Beginning with a brief outline of the background to the transportation problem in Dublin, the article goes on to outline the objectives of the Study and the methods by which these objectives were fulfilled. These methods involved the taking of detailed inventories of Dublin's travel patterns, of its land uses, population and employment, and of its road and public transport systems. Mathematical models were then developed and modified until they could simulate the existing travel patterns to an acceptable degree of accuracy. These models covered the Study's trip generation, modal split, trip distribution and trip assignment stages, and the forms taken by the models are dealt with in the article. The article ends with a summary of the main recommendations of the Dublin Transportation Study. 相似文献
352.
John Zacharias 《先进运输杂志》1994,28(2):141-156
While North American urban regions are served by mechanical modes of transportation, downtowns are largely pedestrian environments. The growth and consolidation of office districts over the last twenty years have revived interest in developing coherent and efficient pedestrian networks, which can be coordinated with other transportation needs within the downtown. Ambitious plans for expansion of the downtown for offices, the retail and service industries as well as for housing and entertainment have been adopted in many North American cities during the 1980s. The successful integration of these large central areas depends to a considerable extent on the implementation of expanded pedestrian networks. This paper discusses certain spatial characteristics of North American cities which call for specific network designs and research into the walking environments of central areas. More knowledge is needed of the relative contributions to pedestrian regeneration of land use combinations, the design of networks and of walking paths. 相似文献
353.
Effects of Model Complexity on the Performance of Automated Vehicle Steering Controllers: Model Development, Validation and Comparison 总被引:2,自引:0,他引:2
Dirk E. Smith John M. Starkey 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1995,24(2):163-181
Recent research on autonomous highway vehicles has begun to focus on lateral control strategies. The initial work has focused on vehicle control during low-g maneuvers at constant vehicle speed, typical of lane merging and normal highway driving. In this paper, and its companion paper, to follow, the lateral control of vehicles during high-g emergency maneuvers is addressed. Models of the vehicle dynamics are developed, showing the accuracy of the different models under low and high-g conditions. Specifically, body roll, tire and drive-train dynamics, tire force saturation, and tire side force lag are shown to be important effects to include in models for emergency maneuvers. Current controllers, designed for low-g maneuvers only, neglect these effects. The follow on paper demonstrates the performance of lateral controllers during high-g lateral emergency maneuvers using these vehicle models. 相似文献
354.
John F. Kain 《先进运输杂志》1988,21(3):197-213
In spite of a broad consensus among transportation analysts that bus rapid transit, whether operating on exclusive rights-of-way or on uncongested high occupancy vehicle lanes or general purpose limited access facilities, provides higher performance and has significantly lower costs per passenger trip than rail transit in medium and low density cities, nearly all Sunbelt cities are building or planning heavy or light rail systems. This paper reviews previous studies of the cost-effectiveness of heavy and light rail transit with bus-rapid transit and the growing experience with busways and transitways and concludes, once again, that some form of bus rapid transit would be a far more effective way of providing improved transit in these cities than heavy or light rail transit. Not only would bus rapid transit be substantially cheaper, but it would provide a higher quality of service than light or heavy rail transit for virtually all users. Finally, the paper speculates on the reasons for the continued, “blind” commitment to rail transit by policymakers in Sunbelt cities and on the refusal of policymakers in all but a few of these cities to even consider bus rapid transit. 相似文献
355.
John L. Eyre 《Maritime Policy and Management》1987,14(3):177-184
356.
John L. Hazard 《Maritime Policy and Management》1978,5(4):269-288
This paper gives a review of port policies of Western European countries and of the USA, and contrasts the roles of the ports of individual countries. Following a discussion on the assessment of port performance, the paper concludes with remarks on principles of port policy and the implications of Western European policies on US port policy. 相似文献
357.
John Lambert Vasco Veenbergen Nathalie Ross 《现代隧道技术》2007,(Z1):42-44
荷兰国家岩土工程研究所(GeoDelft)近来提出了一个称为SmartSoils的新概念.Smart Soils,意即人们所需要的土,其着眼点在于土的某些性质(如渗水性、刚度和强度),以及如何将它们改良,使之能满足工程建设的某些要求.这些新的技术在岩土工程中可以被广泛应用. 相似文献
358.
John Brennan 《汽车与配件》2007,(20):28-29
“现在是预算季——是时候专注于下一年的预算了!”听上去是不是很耳熟?作为向传统的成百供应商提供服务的CSM现在每天都能听到这些。然而,一些前沿的供应商正在将他们的财务预算转变为实时的决策性武器。他们扩充了五年计划,不仅包含了成交量和应纳税收,还有现在和将来所有方面的开支。同时,他们的商业机构在报价、成本计算、和预测方面有惊人的速度。这些提高使实时预算计划不受上级的管理。这些公司有能力来提取六年利润和产品、厂方、客户方的损失信息,并快速作出决策。[编者按] 相似文献
359.
Nasser Lashgarian Azad Amir Khajepour John Mcphee 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(3):249-275
In this work, a full-state feedback controller is designed to prevent the oscillatory instability or snaking behaviour of an articulated steer vehicle. To design the controller, first, a linearized model of the vehicle is developed and analyzed to identify the most important uncertain tire parameters with regard to the snaking mode. By using this linearized model, the equations of motion are represented in the form of a polytopic system, which depends affinely on the most important uncertain tire parameters. Then, by solving some linear matrix inequalities, both the Lyapunov and state feedback matrices for the robust stabilization of the vehicle are found. The performance of the resulting controller is evaluated by conducting several simulations based on the linearized model. To verify the results from the linearized model analysis, some simulations are also done by a virtual prototype of the vehicle in ADAMS. The results based on the linearized model are reasonably consistent with those from the simulations in ADAMS. They show that the controller can effectively stabilize the vehicle during the snaking mode in different driving conditions. 相似文献
360.
为提高非连续变形分析(discontinuous deformation analysis,DDA)方法程序中节理参数赋值的精度,在DDA原程序节理参数定义的基础上,提出了一种节理参数定义方式的改进方法.首先,根据节理的物理力学性质,对原DDA中节理参数定义存在的非一致性问题进行了分析;其次,由节理参数是由构成节理的两个结构面共同决定的特性,对程序中的节理参数进行了重新定义;最后,对DDA原程序中节理参数赋值部分进行了修改和补充,给出了相应的程序计算流程,并通过块体1和块体2的相对滑动算例对改进后的DDA程序进行了验证.研究结果表明:当块体1和块体2交换力学参数时,其间节理仍为同一性质节理;两种工况下,块体1的速度和位移保持一致,说明改进后的DDA程序能够很好地实现同一节理参数赋值的统一. 相似文献