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351.
计算机联锁系统是铁路信号控制系统的核心设备,是有着苛刻安全要求的复杂控制系统。本文采用Prover形式化开发工具对联锁软件安全需求进行形式化验证。通过模型检验的形式化验证方法,遍历系统输入变量的所有状态空间.验证联锁特定应用满足系统安全需求,确保系统的安全性得以正确实现。在保证系统安全性的基础上,以全状态空间查找反例的检验方法进一步提升产品的质量。 相似文献
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本文主要介绍分析新海凤轮自动化电站的配电板单线原理图、配电模式划分与转换、电站主要功能。通过对电站在日常发生的多种故障现象进行简要判断分析,总结出日常对电站管理与维护的经验,以达到维持电站的稳定性、提升电站管理与维护水平目的。 相似文献
356.
Two degree of freedom flow-induced vibration of cylindrical structures in marine environments: frequency ratio effects 总被引:1,自引:0,他引:1
Xiangxi Han Wei Lin Xiaojun Zhang Youhong Tang Chengbi Zhao 《Journal of Marine Science and Technology》2016,21(3):479-492
The flow-induced vibration of a cylindrical structure is a very common problem in marine environments such as undersea pipelines, offshore risers, and cables. In this study, the vortex-induced vibration (VIV) of an elastically mounted cylinder at a low Reynolds number is simulated by a transient coupled fluid–structure interaction numerical model. Considering VIV with low damping ratio, the response, hydrodynamic forces, and vortex shedding modes of the cylinder is systematically analyzed and summed up the universal rule under different frequency ratios. On the basis of the analysis, we find that the frequency ratio α is a very important parameter. It decides the locked-in, beat, and phase-switch phenomena of the cylinder, meanwhile, it also influence the vortex mode of the cylinder. The trajectory of the two degrees of freedom (2 DOF) case at different natural frequency ratios is discussed, with most trajectories having a “figure of 8” shape and a few having a “crescent” shape. A fast Fourier transformation technique is used to obtain the frequency characteristics of the vibration of the cylindrical structure. Using the 2 DOF cylinder model in place of the 1 DOF model presents several advantages in simulating the nonlinear characteristics of cylindrical structures, including the capacity to model the crosswise vibration generated by in-line vibration. 相似文献
357.
The stiffness has a large influence on the behavior of soils. Its value is affected by some of the soils properties, such as the over consolidated ratio(OCR), the effective normal stress, and the plasticity index etc. In this paper, the numerical modeling of soft soils was carried out using an improved elasto-plastic S-clay1 model accounting for degradation of stiffness. The relation between the stiffness and the shear strain was established based on a large number of experimental data. The effects of strain-dependent stiffness of normally consolidated soils and over consolidated soils on the stress-strain behavior were studied through a comparison of the simulations with the experimental results of undrained triaxial compression tests. The results show that the behaviors of soils can be well predicted with the improved constitutive model, particularly before the peak stress. 相似文献
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张传勇 《上海交通大学学报(英文版)》2016,21(1):33-43
As more and more Chinese and foreign-funded banks settle in the China (Shanghai) Pilot Free Trade Zone (CSPFTZ), it has become an imperative to enhance risk management of offshore banking. At the international level, the regulatory effort for offshore banking mainly focuses on tax evasion and money laundering. Existing regulatory frameworks have established standards to identify countries providing facilities for money laundering and developed punitive measures. In terms of strategy, it is suggested that, firstly, relevant regulatory measures should be improved in the short term, and it is necessary to define the scope of offshore banking and regulatory measures for Chinese banks and foreign-funded banks under a suitable legal framework. Secondly, it is necessary to establish risk exposure mechanism and risk evaluation system for the offshore banking in the CSPFTZ, while risk management measures are implemented based on on-site supervision. Thirdly, in the medium and long term, it is necessary to enhance management of potential risks which can be created by offshore banking due to deregulation. Fourthly, on the one hand, specific regulations should be formulated to provide a regulatory basis for taxation; on the other hand, tax informational exchange agreements (TIEAs) may be used as a reference for achieving effective tax regulation. 相似文献
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A novel type of control law was adopted to reduce the vertical acceleration of a fast ferry as well as the motion sickness incidence suffered by the passengers onboard by means of a submerged T-foil. Considering the system changing characteristics under high disturbances, a model-free approach was adopted. In addition, an upgraded proportional-derivative (PD) controller with correction terms resulting from a fast-online estimation of the system dynamics was designed. The overall controller, known as intelligent PD (i-PD) controller, was tested, and the obtained results were compared with those of a classic PD controller. The controllers were also tested in a changing environment and at different operating velocities. The results confirmed the effectiveness of the i-PD controller to smooth the motions with low computational cost control schemes. Furthermore, thanks to ability of the i-PD controller to continually update the estimated dynamics of the system, it showed a better reduction in both vertical motions and the seasickness level of the passengers with the needed robustness under external disturbances and system changing parameters. 相似文献