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71.
伊本·白图泰是14世纪著名的旅行家,他从摩洛哥出发,穿过阿尔及利亚、突尼斯、利比亚、埃及、叙利亚到麦加完成第一次朝觐。后来他又到过东非各国、印度、东南亚国家和中国等。李光斌老先生翻译的《异境奇观——伊本·白图泰游记》是目前最完整的全译本,当我阅读此书时,好象是跟随伊本·白图泰游历中世纪的非洲、欧洲和亚洲。李光斌老先生不仅翻译准确,达到了“信”、“达”、“雅”的境界,而且注释详尽,在考据学上也颇有作为。 相似文献
72.
本文根据冰区浮式核电平台的主要功能及外部环境条件,确定平台的基本形式,并在此基础上进行了系泊系统的优化设计.与以往研究不同的是,考虑到冰区海洋的特殊性,除计算风、浪、流作用情况外,还运用Sdem软件构造了海冰离散单元模型,对海冰与海洋系泊结构物的相互作用过程进行了数值模拟.在此基础上,结合系泊分析软件ANSYS-AQWA的二次开发功能,对平台运动及其系泊系统进行了时域耦合分析,研究了平台在不同环境载荷作用下的运动响应;进行了系泊参数研究,分析一般规律,最终提出了一种满足规范要求且性能优良的系泊方案.研究结果表明:本文提出的冰区核电平台系泊系统可抵抗恶劣的环境影响;通过合理选择系泊缆数量、夹角、预张力大小及顶端倾角等系泊参数,可减小平台运动响应. 相似文献
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合理设置高速公路收费站ETC (Electronic Toll Collection)车道数量,对高速公路通行效率至关重要。针对目前路网中ETC与MTC (Manual Toll Collection)车辆混行的情况,考虑ETC的普及率,结合多用户路网均衡模型和排队论方法,建立基于双层规划模型的高速路网ETC车道优化布设方法。上层模型以车辆总通行时间最小为目标,优化设置进出收费站的ETC车道数量;下层模型为多用户路网均衡模型,反映ETC和MTC车辆的路径和收费车道选择行为。下层模型通过设计收费站的等价拓扑结构,表征收费站的车道使用规则及车辆的收费车道选择行为,并采用排队论方法估计ETC和MTC车道的收费排队时间。根据模型的特点设计了基于主动集的启发式算法,利用参数二进制与拉格朗日函数法确定迭代下降方向,解决了下降方向与步长难以计算的问题;通过内嵌优化函数的方式,保证在主动集转化过程中上层约束均不会失效,且避免了迭代过程中的模型解退化问题。基于上海市绕城高速进行实证分析,结果表明:随着ETC普及率的提升,收费排队时长按照负指数趋势下降;与按比例布设ETC车道的方法相比,所提方法最高可降低57.4%的收费排队时间,且该方法可以避免ETC车道布设过多对于MTC车道通行能力挤压造成的负面效果。研究成果可以有效指导高速路网ETC车道的布设,提高路网通行效率。 相似文献
76.
Reliability Modeling and Maintenance Policy Optimization for Deteriorating System Under Random Shock
Performance degradation and random shock are commonly regarded as two dependent competing risks for system failures. One method based on effective service age is proposed to jointly model the cumulative effect of random shock and system degradation, and the reliability model of degradation system under Nonhomogeneous Poisson processes (NHPP) shocks is derived. Under the assumption that preventive maintenance (PM) is imperfective and the corrective maintenance (CM) is minimal repair, one maintenance policy which combines PM and CM is presented. Moreover, the two decision variables, PM interval and the number of PMs before replacement, are determined by a multi-objective maintenance optimization method which simultaneously maximizes the system availability and minimizes the system long-run expect cost rate. Finally, the performance of the proposed maintenance optimization policy is demonstrated via a numerical example. 相似文献
77.
Hyung Yun Choi Jaeho Shin Chang Jin Oh Jin Ho Bae 《International Journal of Automotive Technology》2017,18(5):851-860
Injury information for vehicle occupants from the body regions of the head, thorax, abdomen, and upper and lower extremities, due to the restraints and interior parts of the vehicle, were extracted from the 2009 ~ 2012 NASS/CDS database. For those cases with high occurrence frequency, a detailed and comprehensive data analysis was performed to find the relationship between the accident, occupant, vehicle, and injury data. A numerical frontal impact sled model with the Hybrid III dummy and the GHBMC human body model was constructed to simulate and identify those injury risks according to NASS/CDS. Among the 5,734 injuries to the aforementioned body regions from frontal crashes are, listed by frequency of occurrence, the lower extremity (27.8 %), upper extremity (21.3 %), thorax (15.1 %), face (10.9 %), spine (8.7 %), head (7.3 %), and abdomen (6.9 %). The main injury sources to the head were the windshield, side structure, and steering wheel. For the thorax and abdomen they were the seat belt and steering wheel. For the lower extremity it was the instrument panel. The main injury patterns for the head were the concussion and the contusion. For the thorax they were vessel laceration and lung contusion. For the abdomen they were laceration and contusion of the organs. For the lower extremity they were bone fracture and ligament rupture. The steering wheel and seat positions were main factors affecting head and thorax injury risks. From the sled impact simulation, high injury risks of the head and thorax were assessed respectively at conditions of steering column tilt down and rear most seat position, which correlated well with the findings from the NASS/CDS data analysis. 相似文献
78.
Zheng Ran Hua Yan Huimin Zhang Yun Li 《International Journal of Automotive Technology》2017,18(6):1109-1119
The AUTOSAR has been developed as the worldwide standard for automotive E/E software systems, making the electronic components of different suppliers to be employed universally. However, as the number of component-based applications in modern automotive embedded systems grows rapidly and the hardware topology becomes increasingly complex, deploying such large number of components in automotive distributed system in manual way is over-dependent on experience of engineers which in turn is time consuming. Furthermore, the resource limitation and scheduling analysis make the problems more complex for developers to find out an approximate optimal deploying approach in system integration. In this paper, we propose a novel method to deploy the AUTOSAR components onto ECUs with the following features. First, a clustering algorithm is designed for deploying components automatically within relatively low time complexity. Second, a fitness function is designed to balance the ECUs load. The goal of our approach is to minimize the communication cost over all the runnable entities while meeting all corresponding timing constraints and balancing all the ECUs load. The experiment results show that our approach is efficient and has well performance by comparing with other existing methods in specific and synthetic data set. 相似文献
79.
随着我国"一带一路"倡议的推进,跨国运输通道的建设成为倡议实施的关键环节之一,而我国建设复杂地质条件下跨国基础设施的经验尚不丰富。"中—尼—印铁路通道"是一条途经尼泊尔,连接中国和印度2个大国的运输通道,基于实地考察,分析该通道建设的必要性及建成后的效益,对线路进行初步规划,并总结该通道建设的难点:铁路轨道坡度大;沿线区域地质构造复杂;周边基础设施落后,施工条件恶劣;大量深长隧道以及大跨径高桥梁;环境以及气候条件复杂。同时对沿线隧道以及桥梁的建设可行性进行分析,并给出施工建议:沿线隧道采用以TBM法为主、钻爆法为辅的施工方法;桥梁建设则因地制宜,根据不同区间的地质特点,采用相应的建设方法。 相似文献
80.