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101.
102.
In this paper, Smith and Roggema examine the solutions emerging in answer to the growing concern in North European shipping companies to adapt to increasing competition and technological diversity and also to attract and retain suitably qualified seafarers. Part 1 describes a move from a situation of lack of stability of crew towards greater crew stability, whilst Part 2 discusses the redistribution of responsibility on board ship, encompassing a change from the caste-like division between officers and ratings and a more flexible division of functions and authority. 相似文献
103.
Dean KARNOPP 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1987,16(5):355-380
A class of active suspensions is presented which provides near optimum isolation of base motion as well as zero static deflection for force disturbances using a simple type of feedback. The load leveling effect is rapid with the system stabilized using isolated mass velocity feedback both for a semi-active damper and for the load leveler. The system can be made energy conservative and fail safe since the system reverts to a reasonable passive isolator if the load leveling effect and even if the active damping effect is switched off. The system could be incorporated in automotive vehicles with some extension of the feedback control to account for several aspects of body motion. 相似文献
104.
105.
Elsayed M. Elbeheiry Ph. D. Student Dean C. Karnopp Professor Mohamed E. Elaraby Professor Chairman Ahmed M. Abdelraaouf Professor Chairman 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1995,24(3):231-258
This bibliographical list classifies the extensive literature related to the dynamic analysis and control design aspects of advanced ground vehicle suspension systems. It is restricted to the design of advanced suspensions for ride quality and safety. Brief generalized notices and definitions are presented. 相似文献
106.
This paper provides an up-to-date review of the previous literature concerning the impact of passenger rail franchising on productivity and costs in Britain, and also presents important new evidence. In particular, the extension in time of previously-used datasets offers the first opportunity to study the impacts of re-franchising. The previous literature emphasised the failure of franchising to produce sustained productivity gains, with a sharp deterioration in productivity after 2000. The new evidence presented offers a somewhat more positive view of the British experience. It suggests that part of what was previously considered to be falling productivity may in fact be due to exogenous changes in diesel prices. Further, new data suggests that the recent increases in costs have resulted in higher quality of service. Finally, competitive re-franchising, and the associated unwinding of short-term management and re-negotiated contracts, seems to have led to improvements in productivity between 2006 and 2008. Nevertheless, it remains the case that passenger rail franchising in Britain has failed to reduce costs in the way experienced in many other industries and in rail in other European countries. The evidence is that somewhat larger franchises, avoiding overlapping and optimising train density and length, should reduce costs. We also speculate that the major increase in wages and conditions of staff might be moderated by longer franchises, although that remains to be proved. This re-appraisal of the British case is important in the context of the wider international interest in the use of franchising in passenger rail, and its relevance to the current review of ways of introducing competition into the domestic rail passenger market in Europe. 相似文献
107.
为提高超高层建筑变形预测精度,对附有条件的深度信念网络(conditional deep belief network,CDBN)模型中权值及阈值调整方法进行了改进,使用LM (Levenberg-Marquardt)算法作为新的模型定权机制,构建了LM-CDBN网络模型;将构建的LM-CDBN超高层变形预测模型应用于一座298 m超高层建筑中;然后用训练误差、预测值拟合度、预测结果稳定性组成的综合评价体系对模型进行了评价;最后,将LM-CDBN模型分别与深度信念模型(deep belief network,DBN)、极限学习机(extreme learning machine,ELM)、基于无迹卡尔曼滤波的支持回归向量机(unscented Kalman filter-support vector regression,UKF-SVR)进行了预测结果对比. 结果表明:在超高层建筑的变形预测中,相比DBN、ELM和UKF-SVR,LM-CDBN预测精度分别提升了32%、55%及24%,模型的信息提取稳定性及处理时变系统非线性问题的泛化能力得到了提高. 相似文献
108.
Permanent Magnet Linear Motors Used as Variable Mechanical Dampers for Vehicle Suspensions 总被引:1,自引:0,他引:1
Dean Karnopp 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1989,18(4):187-200
Linear electrodynamic motors consisting of coils of copper wire interacting with magnetic fields produced by permanent magnets can be used to construct mechanical dampers with a damping coefficient which can be rapidly varied by changing the external resistance connected to the coil. Limitations to the use of these variable dampers arise due to the coil's own resistance and mass and the practically achievable magnetic field. A moving coil system is first analyzed and then modifications to the basic results when a moving magnet design is used are given. The results indicate that for the oscillation freauencies tvoicallv encountered in road vehicle suspensions, electrodynamic variable shock absorbers are feasible. A novel coreless design appropriate for use with high energy permanent magnets is proposed which would significantly reduce the weight of the units. 相似文献
109.
地面激光扫描仪的精度影响因素分析 总被引:3,自引:0,他引:3
尽管地面三维激光扫描技术正被越来越多地应用于多个领域,但对其测量数据的精度评定,至今尚缺乏必要的理论及方法支持。从分析直接测量数据出发,对该类测量仪器误差的主要来源及其对测量数据的影响情况进行了详细分析,构建了地面三维激光扫描仪单个扫描点测量数据的精度评价模型。该模型为基于地面三维激光扫描仪高精度测量项目(如变形监测)的测量成果精度评定,以及测量方案的优化设计提供了所必需的理论基础。 相似文献
110.
Abstract This model statute sets out a mechanism for the management of the coastal zone by the coastal states. It provides a possible state response to the Coastal Zone Management Act of 1972. The authors recognize that most states presently have some form of management or legal control over their coastal zone, and the model statute has been written with the intention that all or parts of it could be adapted to the wide variety of state regulatory schemes with the aim of providing unitary management to the valuable resource of the coastal zone. 相似文献