首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1817篇
  免费   59篇
公路运输   611篇
综合类   438篇
水路运输   419篇
铁路运输   345篇
综合运输   63篇
  2024年   6篇
  2023年   6篇
  2022年   29篇
  2021年   41篇
  2020年   54篇
  2019年   45篇
  2018年   48篇
  2017年   69篇
  2016年   73篇
  2015年   65篇
  2014年   100篇
  2013年   68篇
  2012年   276篇
  2011年   123篇
  2010年   74篇
  2009年   89篇
  2008年   76篇
  2007年   135篇
  2006年   105篇
  2005年   90篇
  2004年   76篇
  2003年   47篇
  2002年   25篇
  2001年   26篇
  2000年   23篇
  1999年   11篇
  1998年   13篇
  1997年   12篇
  1996年   8篇
  1995年   9篇
  1994年   7篇
  1993年   7篇
  1992年   5篇
  1991年   17篇
  1990年   6篇
  1989年   6篇
  1988年   1篇
  1987年   1篇
  1984年   4篇
排序方式: 共有1876条查询结果,搜索用时 15 毫秒
891.
This paper presents a numerical investigation into the dynamics of marine cables which are extensively used in offshore industry. In this numerical study, the Euler-Bernoulli beam model is adopted to develop the governing equations of the cable. Bending stiffness is considered to cope with the low tension problem in local area of towing cable, and thus a more accurate solution with the consideration of the axial elongation can be given.The derived strongly-coupled and nonlinear governing equations are solved by a second-order accurate, implicit,and large time step stable central finite difference method. The quadratically convergent Newton-Raphson iteration method is applied to solving the discrete nonlinear algebraic equations. Then a towed array sonar system(TASS)problem is studied. The numerical solutions agree reasonably well with the experimental data and the simulated results of the references. The specified program of the present paper shows great robustness with high efficiency.  相似文献   
892.
围绕船舶的能效设计指数(EEDI)和能效运营指数(EEOI)标准的制定和实施,如何降低航行船舶的能耗和废气排放一直是人们关注的热点。基于SHIPFLOW软件模拟船后不同布局的预旋三角导管对阻力、自航因子和各效率的影响,优选出性能较好的布局,并通过水池试验验证。为船舶节能装置的设计和应用提供数值参考。  相似文献   
893.
拖曳系统运动传递计算   总被引:2,自引:0,他引:2  
由母船、拖缆和拖体构成的拖曳系统,在拖航作业中,母船受风浪扰动发生升沉和纵摇运动,水面扰动沿缆传递至拖体,影响探测设备性能。文中研究的合理简化的母船波浪运动预报模型、结合已有的拖缆动力学计算模型耦合拖体空间运动模型,构造衔接条件和转换关系式,建立较为完整的水下拖曳系统运动传递模型。编制相应计算程序,计算了二段式拖曳方式对扰动的传递,归纳其扰动传递特性。表明该模型可应用于拖曳运动稳定的设计分析。  相似文献   
894.
895.
A meshless numerical simulation method, the moving-particle semi-implicit method (MPS) is presented in this paper to study the sloshing phenomenon in ocean and naval engineering. As a meshless method, MPS uses particles to replace the mesh in traditional methods, the governing equations are discretized by virtue of the relationship of particles, and the Poisson equation of pressure is solved by incomplete Cholesky conjugate gradient method (ICCG), the free surface is tracked by the change of numerical density. A numerical experiment of viscous liquid sloshing tank was presented and compared with the result got by the difference method with the VOF, and an additional modification step was added to make the simulation more stable. The results show that the MPS method is suitable for the simulation of viscous liquid sloshing, with the advantage in arranging the particles easily, especially on some complex curved surface.  相似文献   
896.
This paper presents the optimisation of damping characteristics in bogie suspensions using a multi-objective optimisation methodology. The damping is investigated and optimised in terms of the resulting performances of a railway vehicle with respect to safety, comfort and wear considerations. A complete multi-body system model describing the railway vehicle dynamics is implemented in commercial software Gensys and used in the optimisation. In complementary optimisation analyses, a reduced and linearised model describing the bogie system dynamics is also utilised. Pareto fronts with respect to safety, comfort and wear objectives are obtained, showing the trade-off behaviour between the objectives. Such trade-off curves are of importance, especially in the design of damping functional components. The results demonstrate that the developed methodology can successfully be used for multi-objective investigations of a railway vehicle within models of different levels of complexity. By introducing optimised passive damping elements in the bogie suspensions, both safety and comfort are improved. In particular, it is noted that the use of optimised passive damping elements can allow for higher train speeds. Finally, adaptive strategies for switching damping parameters with respect to different ride conditions are outlined and discussed.  相似文献   
897.
In recent studies, the dynamic response of a passenger car to a gyrostat was investigated for a series of driving manoeuvres, but the gyrostat was assumed to be rigidly supported, thus neglecting the effect of rotor precession. The aim of the present study is the modelling and investigation of the gyrostat-vehicle interaction for elastically mounted gyrostats. For this purpose, a general model describing the motion of a gyrostat elastically supported by a moving platform is derived. Emphasis is placed on the mathematical derivation, where all considerations that are necessary to arrive at the final result are included. Thus, the presented considerations and results can be easily adopted and are suitable to serve beyond their actual purpose as a reference work for other applications. The derived model is tested with the aid of vehicle dynamics simulations and the simulation results prove to be consistent with the results of the rigid attachment model, provided that the elastic approach is subjected to high-bearing stiffnesses. However, it is shown that at lower bearing stiffnesses the solutions are progressively different, since low-bearing stiffnesses enable the gyrostat to move, due to the compliance of the bearings itself, relative to the vehicle chassis with high-angular velocities.  相似文献   
898.
ABSTRACT

This paper presents a review of various works that highlight the importance of introducing the variability of the road-track/vehicle system into dynamic simulations as soon as this latter is meant to be predictive. The first section of the paper presents the Uncertainty Quantification, Verification and Validation method (UQ-VV). This latter proposes tools to model uncertainties, to associate a confidence to the prediction of quantities of interest and to estimate the probability of occurrence of different scenarios. The method is illustrated by various examples mainly from the rail domain but also from the road sector. The second section summarises application examples of predictive modelling, robust optimisation and calibration.  相似文献   
899.
踏面形状对地铁车辆动力学性能的影响   总被引:5,自引:0,他引:5  
不同的车轮踏面形状与同一钢轨匹配时具有不同的轮轨接触几何关系,影响车辆的动力学性能.分析比较了我国LM磨耗型踏面和德国DIN5573踏面对地铁车辆动力学性能的影响.结果表明,采用DIN5573踏面时车辆的运行稳定性优于LM磨耗型踏面,而曲线通过性能则相对较差.  相似文献   
900.
120 km/h货车提速综合试验动力学性能分析   总被引:1,自引:1,他引:0  
陈雷  王新锐 《铁道车辆》2007,45(8):27-34
我国提速综合试验既是对列车在提速条件下对线桥设备(包括钢轨、轨枕、道岔、路基、路桥过渡段和桥涵等)的动力作用的试验,又是对车辆动力学性能进行的一个充分的验证性能试验。文章通过对比分析近年来我国提速综合试验的测试线路、试验车辆、运行特点和测试数据,对我国综合提速试验中120km/h货车动力学性能进行了比较全面的总结与分析,指出了我国120km/h货车动力学性能方面存在的主要问题,并提出了解决问题的建议。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号