水面舰艇鱼雷防御系统近期发展趋势

对当前水面舰艇防御鱼雷的作战过程进行了分析,总结了水面舰艇反鱼雷作战的新特点;对水面舰艇鱼雷防御系统的现状进行了分析,依据水面舰艇反鱼雷作战的特点,从作战使用的角度出发,分析了现役水面舰艇鱼雷防御系统在设计上存在的不足,以及上述不足给作战带来的不利影响,并在此基础上,对下一步水面舰艇鱼雷防御系统的设计思路提出了改进建议,并结合当前的科技与工业水平,对水面舰艇鱼雷防御系统近期的发展趋势进行了分析与预测。     

A frequency-based maritime container assignment model

This paper transfers the classic frequency-based transit assignment method of Spiess and Florian to containers demonstrating its promise as the basis for a global maritime container assignment model. In this model, containers are carried by shipping lines operating strings (or port rotations) with given service frequencies. An origin–destination matrix of full containers is assigned to these strings to minimize sailing time plus container dwell time at the origin port and any intermediate transhipment ports. This necessitated two significant model extensions. The first involves the repositioning of empty containers so that a net outflow of full containers from any port is balanced by a net inflow of empty containers, and vice versa. As with full containers, empty containers are repositioned to minimize the sum of sailing and dwell time, with a facility to discount the dwell time of empty containers in recognition of the absence of inventory. The second involves the inclusion of an upper limit to the maximum number of container moves per unit time at any port. The dual variable for this constraint provides a shadow price, or surcharge, for loading or unloading a container at a congested port. Insight into the interpretation of the dual variables is given by proposition and proof. Model behaviour is illustrated by a simple numerical example. The paper concludes by considering the next steps toward realising a container assignment model that can, amongst other things, support the assessment of supply chain vulnerability to maritime disruptions.     

“低碳经济”背景下公路隧道照明节能策略

目前我国公路隧道运营照明存在的突出问题主要表现在:照明设计参数有待完善、照明控制方式较为落后、照明节能理念存在误区、照明设施养护未得重视。文章基于建设"环境友好型"公路隧道理念,从系统工程角度提出公路隧道照明节能的15项重要措施,包括准确测试洞外亮度、优化照明设计参数、选择使用节能光源等,基本涵盖公路隧道照明技术性节能、结构性节能、管理性节能的各个方面。工程实践表明,这些技术和措施可实现公路隧道照明综合节能20%以上的总体目标,具有较好的生态效益、经济效益和社会效益。     

天然气站往复式压缩机活塞失效分析

针对天然气站往复式压缩机活塞的断裂事故,运用失效分析方法,开展了活塞断口扫描电镜分析、能谱和金相分析。根据断口形貌的电镜和金相观察结果,结合理论知识,分析确定了该活塞发生断裂事故的主要原因,即在特定工况下该活塞的材料缺陷是造成断裂的主要因素。     

西山特长隧道斜井进入正洞交叉口施工技术

太古高速公路西山特长隧道全长13.654 km,是国内目前在建最长的公路隧道。在斜井进入正洞交叉口的施工中,成功采用台阶法矩形断面垂直挑顶直接转入正洞施工方案,通过优化调整设计参数,采取加强支护、减震爆破等技术措施,实现了斜井安全、简便、快速地转入正洞的施工。     

18单元线极化径向线阵列天线优化及实验研究

为了改善18单元线极化径向线阵列天线的辐射性能,通过改变子阵馈电网络封口形状并优化馈电探针、改进单元天线和适当减小阵列天线单元间距3种方法,对阵列天线进行优化,对反射特性和辐射特性进行理论分析、数值仿真和实验研究.仿真结果表明:中心频率1.57 GHz上的反射系数为0.067,增益为18.73 dBi,轴比为-39.82 dB;在1.43～1.76 GHz范围内,反射系数小于0.15.实验结果表明:中心频率1.57 GHz上的驻波比为1.19(对应的反射系数为0.087),增益为17.65 dBi,轴比为-39.2 dB;在1.47～1.77 GHz范围内驻波比小于1.4(对应的反射系数为0.17).仿真结果与实验结果相符.     

杭长客专引入鹰潭枢纽方案分析

通过对鹰潭铁路枢纽地理位置及现状的分析,在杭长(杭州-长沙)客专引入后,指出枢纽急待解决的问题。充分结合拟建工程,根据对预测运量及组织运输的分析,对枢纽总图规划进行研究,提出三个可选方案,优化比选后认为在城市北侧设新站的方案为最佳方案,并对此方案进行进一步说明。     

灰色模型在中长期用水量预测中的应用

为实现供水管网经济、可靠、科学的规划改扩建,给出一种基于记录时间较短、历史数据较少的用水量序列的GM(1,1)预测方法。该预测方法把原始用水量序列累加处理生成新序列后,用指数关系式拟合,通过构造参数矩阵,确定辩识参数,建立灰色模型的微分方程。通过对灰色预测方法建模机理的研究建立城市用水量预测GM(1,1)模型,并以东北某大型城市用水量为原始数据进行实际预测,模型精度检验的结果表明该模型的预测等级为高精度预测。该预测方法应用于S市的中长期用水量预测,为S市供水规划改扩建提供有效依据。     

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公路运输效率高低是衡量公路运输发展水平的重要依据.随着可持续发展战略的实施,经济增长方式由粗放型向集约型转变,必然要求公路运输提高生产效率,优化发展模式.本文从投入和产出两个层面建立公路运输效率评价指标体系,基于DEA方法构建了综合评价模型,定量测算公路运输综合效率、技术效率和规模效率,并采用31省份的投入产出截面数据进行实证分析.结果显示：半数省份DEA有效,公路运输综合效率存在较明显的地域差异;2/3的省份达到规模效益递减或不变,增加要素投入对提高综合效率不具积极性;资源投入过度、要素使用效率低下是导致运输效率不高的主要因素.最后针对公路运输发展中存在的主要问题提出相应的发展模式.     

Modeling Correlation of Family Holiday Activities Based on Structural Equation Model

Previous researches in activities-decision have more in-depth study in context of individuals, while less work has been done within household activity decisions. The structural equation model is applied to analyze the relationship of three household activity categories on holiday using data from 2009 Jinan travel survey. Six attributes were first chosen as exogenous variables for the structural equation model. Meanwhile, six activity characteristic indexes were selected as endogenous variables including activity duration time and activity times in three kinds of activity, hereby Subsistence activity, maintenance activity and discretionary activity. respectively. Then, the paper attempted to discuss the correlation of all types of activities behavior through analyzing not only the influence of household economics and family members factors on activity but the correlation of holiday activities. The research shows that complex relationships among composition of the family, economic status, and activities-decision can be captured by the structural equation model structure. Specifically, the results show that flexibility of three categories activities will affect the activities of decision-making.