Management considerations for accreting shorelines

Abstract

Natural coastal accretion in the United States occurs at river mouths, spits across embayments, inlets, capes and cuspate forelands, and pocket beaches. Human‐induced accretion occurs updrift of groins and jetties, landward of breakwaters, and in locations which are artificially nourished. Coastal accretion is usually temporary (years to tens of years). Erosion may occur due to deflection of streams and tidal current channels or to changes in sea level, weather patterns, or sediment budgets. A focus on ownership disputes or use of accreted land draws attention away from the long‐term problem of the development of land which may be subject to future erosion. Control mechanisms should be in place to direct development on accreting shorelines to make more effective use of the resource.     

后示范高等职业院校发展规划的战略设计

战略规划设计是高等职业院校战略规划的先导与重点。本文从高等院校战略管理的视角梳理了高等学校战略规划的演进流程、高职院校制定与实施战略规划的条件,介绍了战略规划流派与战略规划的编制模式,重点分析了战略规划主体文本结构的战略目标体系、完成战略目标的战略链、战略规划实施的重点项目与战略措施,对处于起草阶段的高职院校战略规划编制具有一定的指导价值。     

Optimization models to characterize the broadcast capacity of vehicular ad hoc networks

Broadcast capacity of the entire network is one of the fundamental properties of vehicular ad hoc networks (VANETs). It measures how efficiently the information can be transmitted in the network and usually it is limited by the interference between the concurrent transmissions in the physical layer of the network. This study defines the broadcast capacity of vehicular ad hoc network as the maximum successful concurrent transmissions. In other words, we measure the maximum number of packets which can be transmitted in a VANET simultaneously, which characterizes how fast a new message such as a traffic incident can be transmitted in a VANET. Integer programming (IP) models are first developed to explore the maximum number of successful receiving nodes as well as the maximum number of transmitting nodes in a VANET. The models embed an traffic flow model in the optimization problem. Since IP model cannot be efficiently solved as the network size increases, this study develops a statistical model to predict the network capacity based on the significant parameters in the transportation and communication networks. MITSIMLab is used to generate the necessary traffic flow data. Response surface method and linear regression technologies are applied to build the statistical models. Thus, this paper brings together an array of tools to solve the broadcast capacity problem in VANETs. The proposed methodology provides an efficient approach to estimate the performance of a VANET in real-time, which will impact the efficacy of travel decision making.     

改进的协同航路分配优化模型及算法研究

为优化协同航路分配程序,利用基尼系数定义一个新的公平性能指标,构建同时兼顾效率和公平性的双目标非线性整数规划模型,采用基于航班优先级排列的染色体编码方式设计一种改进的遗传算法,融合满意解的选择过程.仿真算例结果显示,与现有算法相比,改进遗传算法得到的最终满意解使空域运行效率提高9.3%,航空公司公平性提高33.7%.结果表明,改进的遗传算法能快速获得真实帕累托前沿,且最终满意解能在空域运行效率和资源分配公平性上得到显著提升,说明本文模型及算法合理.     

机场停机位指派模型及算法

为探索中小型机场停机位指派问题有效合理的解决方法,以乘客最小行走距离为优化目标,建立了中小型机场停机位整数规划指派模型,利用改进的启发式算法进行了求解。该算法可以缩小搜索空间,在最坏情况下的计算复杂度是多项式的,优于CPLEX软件的指数级计算复杂度,具有更高的计算效率;与CPLEX结果相比,距离误差仅为5.2%,指派结果令人满意。     

用于滑油自动加注的油量控制装置

某特种装备有四百个润滑点,分布广且漏点太多,既需要对每个点定量供给滑油,也需要对所有漏点渗漏情况进行监控,同时也要求加油自动化,因此有必要研制能自动加注滑油的油量控制装置以满足上述要求。装置利用布置在不同位置的6个电感式传感器的信号实现阀件与筒体活塞按软件设定程序动作,达到自动加油和监控的目标;设计和制造了装置中重要的专用阀件,依靠软件程序设计弥补了硬件功能上的不足,并对整个装置按实际工况进行了12万次加注油的可靠性试验,其技术性能仍稳定不变。现已应用到两套某特种装备中,使用效果符合预期。     

The multi-objective railway timetable rescheduling problem

Unexpected disruptions occur for many reasons in railway networks and cause delays, cancelations, and, eventually, passenger inconvenience. This research focuses on the railway timetable rescheduling problem from a macroscopic point of view in case of large disruptions. The originality of our approach is to integrate three objectives to generate a disposition timetable: the passenger satisfaction, the operational costs and the deviation from the undisrupted timetable. We formulate the problem as an Integer Linear Program that optimizes the first objective and includes $\epsilon$-constraints for the two other ones. By solving the problem for different values of $\epsilon$, the three-dimensional Pareto frontier can be explored to understand the trade-offs among the three objectives. The model includes measures such as canceling, delaying or rerouting the trains of the undisrupted timetable, as well as scheduling emergency trains. Furthermore, passenger flows are adapted dynamically to the new timetable. Computational experiments are performed on a realistic case study based on a heavily used part of the Dutch railway network. The model is able to find optimal solutions in reasonable computational times. The results provide evidence that adopting a demand-oriented approach for the management of disruptions not only is possible, but may lead to significant improvement in passenger satisfaction, associated with a low operational cost of the disposition timetable.     

圆端形沉井内力比较

在沉井截面设计中,针对双孔圆端形截面,通过等截面内力计算得知隔墙与沉井连续处弯矩最大,考虑在隔墙与沉井连续处采用变截面。为节省材料和成本,寻求合理截面,采用等截面与变截面2种截面形式进行设计。以所给工程为例,通过编制电算程序,计算双孔圆端形沉井等截面与变截面的内力,比较和分析2种截面在相同圆弧段半径及同矩形段长度下的内力,以寻找圆端形沉井设计的最优截面形式。     

虹桥综合交通枢纽开发融资策划

虹桥综合交通枢纽是上海城市交通的重大枢纽,属于城市大型交通基础设施.分析了虹桥综合交通枢纽的基本经济属性,对枢纽设施进行了拆分,并根据可经营性、可拆分性将枢纽设施分成4种类型;基于设施分类,对枢纽系统的投资平衡进行了研究,提出了4类设施不同的融资方式,以及由此所形成的投资分工和多元化投资主体结构.     

驼峰编组场纵断面设计

本文介绍一种采用VB语言开发的驼峰纵断面调整的程序,该程序在计算机绘图软件CAD中运行,利用VB语言开发的程序来操纵CAD,使CAD自动绘制纵断面设计图并计算土石方量。