冲击毁伤载荷作用下新型舰船舱壁结构型式研究

本文对高速破片与冲击波载荷联合作用下典型舰船舱壁结构的动态响应过程进行数值模拟研究.基于结构吸能和破片平均剩余速度的评判标准,对比分析3种新型夹芯板双层舱壁(I型、X型、V型)抗冲击毁伤特性.研究结果表明,在相同高速破片与冲击波载荷联合作用下,破片穿透V型夹芯板双层舱壁结构的平均剩余速度最小,并且V型夹芯板结构吸能最多;3种新型夹芯板舱壁结构抗冲击性能均强于典型单层舱壁结构.     

Modelling with joint choice of ports and countries of origin and destination: application to Colombian ports

Literature has focused on studying port choice independently or as an element of a supply chain without considering the joint selection with the country of origin/destination of the imports/exports. However, the characteristics and location of a port may make it more attractive to mobilise more freight from/to some particular countries rather than others, making the port choice decision dependent on the country of origin/destination of the cargo. This article proposes advanced econometric models to evaluate simultaneously port choice and the country of origin/destination choice for Colombian imports and exports. Findings suggest that for imports and exports domestic freight rate is the most important variable for the joint choice process. Also, for exports, maritime transit time is more relevant than for imports, while for the frequency of shipping lines the opposite is true. The existence of a trade agreement and the gross domestic product per capita also have a significant influence on the election of a country for exports/imports.     

基坑变形组合预测分析及安全性评价

为提高基坑变形预测精度及合理评价基坑所处的安全状态,提出以支持向量机、极限学习机和GM(1,1)模型为单项预测模型,构建定权法、非定权法确定组合权值的组合预测模型,并利用累计变形量与变形控制值构建基坑变形的安全性评价指标,以判断基坑所处的安全状态,且采用重标极差法分析基坑安全性的发展趋势。实例分析表明： 1）组合预测较单项预测具有更高的预测精度,且能有效降低预测风险,增加预测结果的稳定性; 2）非定权组合的预测精度要略优于定权组合的预测精度,且以BP神经网络权值法的组合效果最优; 3）通过对某基坑的安全性分析,得知该基坑处于危险阶段,需采取必要的安全措施,且预测结果与安全分析结果一致,验证了预测方法和安全性评价方法2种分析方法的有效性和准确性。     

An agent‐based simulation model to assess the impacts of introducing a shared‐taxi system: an application to Lisbon (Portugal)

This paper presents a new concept of urban shared‐taxi services. The proposed system has a new organisational design and pricing scheme that aims to use the capacity in traditional taxi services in a more efficient way. In this system, a taxi acting in ‘sharing’ mode offers lower prices to its clients, in exchange for them to accept sharing the vehicle with other persons who have compatible trips (time and space). The paper proposes and tests an agent‐based simulation model in which a set of rules for space and time matching between a request of a client and the candidate shared taxis is identified. It considers that the client is only willing to accept a maximum deviation from his or her direct route and establishes an objective function for selecting the best candidate taxi. The function considers the minimum travel time combination of pickup and drop‐off of all the pool of clients sharing each taxi while allowing to establish a policy of bonuses to competing taxis with certain number of occupants. An experiment for the city of Lisbon is presented with the objectives of testing the proposed simulation conceptual model and showing the potential of sharing taxis for improving mobility management in urban areas. Results show that the proposed system may lead to significant fare and travel time savings to passengers, while not jeopardising that much the taxi revenues. Copyright © 2014 John Wiley & Sons, Ltd.     

Validation of traffic flow models with respect to the spatiotemporal evolution of congested traffic patterns

We propose a quantitative approach for calibrating and validating key features of traffic instabilities based on speed time series obtained from aggregated data of a series of neighboring stationary detectors. The approach can be used to validate models that are calibrated by other criteria with respect to their collective dynamics. We apply the proposed criteria to historic traffic databases of several freeways in Germany containing about 400 occurrences of congestions thereby providing a reference for model calibration and quality assessment with respect to the spatiotemporal dynamics. First tests with microscopic and macroscopic models indicate that the criteria are both robust and discriminative, i.e., clearly distinguishes between models of higher and lower predictive power.     

真空-堆载联合预压法处理吹填淤泥试验研究

真空-堆载联合预压法的实质是将真空预压法的负压固结理论与堆载预压法的正压固结理论进行联合,使得土体固结达到最大化通过理论分析,论述了真空-堆载联合预压下基于孔隙水压力和沉降的平均固结度计算方法.结合大面积吹填淤泥软基处理的工程实际,通过对孔隙水压力、沉降等进行观测,提出了有效地控制加载速率与加载周期的方法;研究了孔隙水压力变化规律,并结合工程实际进行了平均固结度的验算分析,表明该计算方法存在一定的合理性.     

飞轮储能系统建模与仿真研究

为研究独立电力系统采用飞轮储能系统对大功率脉冲负载的供电性能,本文在分析了飞轮储能系统工作原理基础上,对飞轮储能系统建模与仿真开展了研究。采用了PSCAD/EMTDC软件搭建按照其实际组成搭建了SPWM控制的变流器及触发控制信号仿真模型,利用具有大转动惯量、小摩擦系数和小阻力转矩的负载模拟飞轮转子,建立了飞轮储能系统的全系统模型。通过对建立的模型进行仿真,给出了飞轮储能系统在储能状态、放能状态及两者之间的转换过渡时刻的转速、转矩、电流及母线直流电压响应曲线,深入分析表明,该仿真结果与理论完全一致,证明了飞轮储能负载的仿真模型是正确有效的。研究的相关结论可用于相关电力系统供电稳定性的仿真设计。     

导弹中末段制导导引律转换研究

文章研究了导弹由中间段制导律向末段制导律转换的问题,提出了一种可变导引系数的组合制导律,即可变系数组合比例导引律（ACNG）。仿真结果表明,该导引律总体优于纯比例导引和固定系数组合比例导引律,中末段弹道过渡平滑,衔接良好,有利于中末段的交班,同时降低了导弹的需用过载。     

基于CAN总线的汽车组合仪表校验系统的设计

论述了系统设计中的几个主要模块,实现了组合仪表总成校验、参数写入及电路板检测,该系统适合各类数字仪表检测。