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901.
Capacity and QoS based codebook construction for MIMO precoded spatial multiplexing systems with limited feedback 总被引:1,自引:0,他引:1
This paper deals with the design and performance analysis of transmit precoder optimization for multiple input multiple output (MIMO) systems with limited feedback of channel state information. A capacity criterion based optimal codebook construction algorithm for MIMO precoded spatial multiplexing systems is pre-sented. The optimal precoder structure combining precoding and power allocation is employed. Simulation results show that the capacity criteria based codebook can achieve higher capacity than that of equally power allocation based codebook of previous research. 相似文献
902.
公路超高的灵活性设计分析 总被引:1,自引:0,他引:1
超高设计影响因素较多,具有一定的路段差异性.在阐述超高值与行车安全关系的基础上,分析了各超高设计要素及其影响因素,并结合实例说明超高灵活性设计的思路. 相似文献
903.
导致渗碳齿轮接触疲劳裂纹形成与扩展的动力参数是齿轮次表面所受的最大切应力τmax与其表面硬度的比值,减小该比值可延缓齿轮表面接触疲劳裂纹形成与扩展过程,提高齿轮疲劳寿命.分析了强化喷丸工艺对渗碳齿轮次表面所受τmax和表面硬度的影响,通过强力喷丸引入的冷作硬化可使渗碳齿轮表面硬度明显提高;引入的高残余压应力可使渗碳件次表面所受的τmax显著减小.试验表明,齿轮渗碳后再按最佳工艺进行强化喷丸后,可显著提高齿轮表面的疲劳强度. 相似文献
904.
905.
某特大桥自建成以来,基础开裂严重,且裂缝在不断发展,以至危及到大桥的安全及整条铁路线的运营。在调查统计全桥病害情况、设计图纸及地质资料的情况下,运用大型有限元程序ANSYS对大桥基础进行了空间受力分析,找出了产生病害的原因,并提出了切实可行的加固方案。 相似文献
906.
浅析新型支挡结构在铁路运营线中的应用优势 总被引:3,自引:2,他引:1
针对铁路运营线的特点,分析新型支挡结构的优势,倡议推广应用新型支挡结构。 相似文献
907.
908.
Hang Yu Jihong Chen Lihua Luo Ding Liu Caimao Tan 《Maritime Policy and Management》2018,45(6):770-786
The degree of container dispersion at a transhipment terminal is measured by an index termed container location dispersion, which represents the range, both horizontal and vertical, of all containers for ship loading that are scattered in the yard. First, this paper identifies the impacts of container location dispersion on loading performance with insufficient or sufficient equipment deployment in real-life settings at a terminal. Then, we investigate those scenarios with different levels of interference. This research aims to explore the relationship between the container location dispersion and Gross Crane Rate (GCR) stability at a transhipment terminal and proposes a discrete-event driven simulation model for this purpose. All data in our experiments are extracted from the terminal operation system at a real-life container terminal. It is concluded from a series of experiments that the container location dispersion well captures the overall performance of container terminal handling and can be used for yard template optimization and management. Implications of this investigation are discussed in the context of the yard template design and improvement in the overall performance of a container transhipment terminal. 相似文献
909.
About 63% of the world’s shipping accidents are recurrent—they occur to ships that have already experienced at least one prior accident. Therefore, reducing recurrent accidents can contribute significantly to maritime safety. We study the factors affecting both first and recurrent accidents, by focusing on the duration between two accidents. Cox proportional hazard models are applied to ship accident data from 1996 to 2015, and the results identify which ships have a high risk of recurrent accidents, based on ship attributes, ship supply and market conditions, shipbuilding country, previous accident type, and ship type. The recurrent rate is high when the ship involved in the accident is old, small, flies a flag of convenience, and has no detention record. In addition, the accident risk increases when the shipping market faces a high bunker price, overcapacity in supply, a high time charter rate, or low newbuilding price. On the other hand, ships built in China and Japan have lower recurrent accident rates than those built elsewhere, although ships built in China have earlier first accidents than do others. General cargo ships have the highest recurrent accident rate, followed by dry bulkers, container ships, and tankers, in that order. 相似文献
910.
Yue Shi Bin Li Jiannan Luo 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2019,57(3):336-368
Emergency brake technologies have always been a major interest of vehicle active safety-related studies. On homogeneous surfaces, traditional anti-lock brake system (ABS) can achieve efficient braking performance and maintain the handling capability as well. However, when road conditions are time variant during the braking process, or different at the bilateral wheels, braking stability performance is likely to be degraded. To address this problem and enhance ABS performances, a practical identifier of road variations is developed in this study. The proposed identifier adopts a statechart-based approach and is hierarchically constructed with a wheel layer and a full vehicle layer identifier. Based on the identification results, modifications are made to a four-phase wheel-behaviour-based ABS controller to enhance its performance. The feasibility and effectiveness of the proposed identifier in collaborating with the modified ABS controller are examined via simulations and further validated by track tests under various practical braking scenarios. 相似文献