喷水推进船避免喷泵气蚀的仿真研究

为了解决喷水推进船在各种工况下,喷泵工作在气蚀区的问题,利用Simulink与MFC(Microsoft Foundation Class)集成的方法开发出了可用于制定喷水推进装置在回转、加速等工况下,避免喷泵在空化区运行的工作制的仿真程序.利用开发出的仿真程序对特定工况下的最大柴油机转速、最大喷泵转角以及最短加速时间做了仿真计算.该计算结果对喷水推进艇避免喷泵气蚀的操作规程有一定的参考价值.     

基于接口库的城市轨道交通工程设备接口研究

研究目的：城市轨道交通工程建设过程中涉及大量设备,各种设备间接口的合理匹配是影响设备联调和工程进度的重要因素之一.为了优质、高效地解决设备间接口匹配问题,本文提出了一个设备接口解决方案。 研究方法：运用信息技术和并行工程原理,定义了运用面向对象方法封装的设备、设备接口和匹配等概念,阐述了设备接口匹配原理和匹配过程。 研究结果：建立了设备接口库和专家支持库,并构建了设备接口管理系统的实现框架,为工程相关的各建设单位创建了一个协同工作环境。 研究结论：本方案能有效地规划设备和设备接口匹配,控制设备匹配过程,积累匹配经验并改进匹配效率.同时,也大大缩短了各参建单位在空间和时间上的距离,实现了设备接口的统一并行管理、实时虚拟联调。     

Optimisation of motorway operations via ramp metering and variable speed limits

This paper presents a modelling and optimisation framework for deriving ramp metering and variable speed control strategies. We formulate the optimal control problems aiming to minimise the travel delay on motorways based upon a macroscopic cell transmission model of traffic. The optimal ramp metering optimisation is formulated as a linear programming (LP) while the variable speed control problem is formulated as a mixed integer LP. The optimisation models are applied to a real scenario over a section of M25 motorway in the UK. This paper also includes various analyses on the sensitivity of the optimal control solutions with respect to different network configurations and model assumptions.     

高等职业院校学生基本职业能力的培养与训练

高等职业技术教育承担着为经济社会发展培养高素质、技能型人才的任务。学生的专业素质培养和专业能力实训已经得到重视,通过专业建设、课程改革、仿真型实训基地建设、顶岗实习等方式得到系统全面地培养,但专业之外的基本职业能力训练却未能系统、全覆盖地实施,一定程度上影响和制约着高等职技院校的培养质量,影响着毕业生的职业发展。根据高等职业教育的培养目标,对学生的职业能力要素以及训练方法进行论述,为高等职业院校开展基本职业能力实训提供系统化、操作性的指导方案。     

对当前施工招标最高限价编制、审查的几点建议

针对公路工程施工招标最高限价编制和审查中,容易忽视的问题,提出自己的观点和看法,供同行参考。     

Truck capacity analysis in a cross‐dock transportation network considering direct shipment

In a transportation network, decision making parameters may change and may cause the optimum value of objective function to vary in a specific range. Therefore, managers try to identify the effects of these changes by sensitive analysis to find appropriate solutions. In this paper, first, a model for cross‐dock transportation network considering direct shipment is presented, and then an algorithm based on branch and bound algorithm and dual price concept for sensitive analysis is developed. When managers encounter problems such as budget limit, they may decide to change the capacity of trucks as a procedure to reduce the transportation costs of the network. The algorithm provides a useful lower bound on the solutions of the problems and makes it easy for the managers to eliminate inappropriate options of truck capacities, which cannot lead to cost reduction. To verify the algorithm, an example will be given at the end of the paper. Copyright © 2013 John Wiley & Sons, Ltd.     

The optimal dual-pricing policy of mall parking service

In studies of parking policy, the role of parking pricing has been addressed. Most researches have focused on the determination of a proper price for city parking spaces that are open to the public and it is now evident that price is used by authorities as a tool to manage transport demand. However, studies of parking pricing that pertain to privately-owned parking resources are few and in particular, the problem of setting a proper price for physical market parking has rarely been studied, such as a mall’s ‘dual-pricing portfolio’ decision for the simultaneous determination of a parking fee and the consumer spending required for free parking (i.e., the ‘threshold’). This is a common problem for most malls, but the different agents involved (e.g., the visitors, the mall, the marketplace and the parking lot departments) usually have diverse goals, so the decision must take account of a multiplicity of criteria and subtle relationships. In order to systematically support this type of inter-departmental decision process, a decision model that includes an analytical decision-aid process and the relevant programming models is established. A numerical example verifies the proposed model by taking the data for a mall in Taiwan and the implications, in terms of management, are given. This systematic computational model can be generalized to any type of commercial market that requires a (new) parking pricing policy.     

Optimization method of alternate traffic restriction scheme based on elastic demand and mode choice behavior

As a countermeasure to urban traffic congestion, alternate traffic restriction (ATR) involves a certain proportion of automobiles being prohibited from entering pre-determined ATR districts during specific time periods. The present study introduces an optimization method for ATR schemes in terms of both their restriction districts and the proportion of restricted automobiles. As a Stackelberg game between traffic policy makers and road users, the ATR scheme optimization problem is established using a bi-level programming model, with the upper-level examining an ATR scheme aimed at consumers’ surplus maximization under the condition of overload flow minimization, and the lower-level synthetically optimizing elastic demand, mode choice (private car, public transit and park-and-ride) and multi-class user equilibrium assignment. A genetic algorithm based on the graph theory is also proposed to solve the bi-level programming model with a gradient project algorithm for solving the lower-level model. To our knowledge, this study represents the first attempt to theoretically optimize an ATR scheme using a systematic approach with mathematical model specification.     

A dynamic evacuation model for pedestrian–vehicle mixed-flow networks

In urban emergency evacuation, a potentially large number of evacuees may depend either on transit or other modes, or need to walk a long distance, to access their passenger cars. In the process of approaching the designated pick-up points or parking areas for evacuation, the massive number of pedestrians may cause tremendous burden to vehicles in the roadway network. Responsible agencies often need to contend with congestion incurred by massive vehicles emanating from parking garages, evacuation buses generated from bus stops, and the conflicts between evacuees and vehicles at intersections. Hence, an effective plan for such evacuation needs to concurrently address both the multi-modal traffic route assignment and the optimization of network signal controls for mixed traffic flows. This paper presents an integrated model to produce the optimal distribution of vehicle and pedestrian flows, and the responsive network signal plan for massive mixed pedestrian–vehicle flows within the evacuation zone. The proposed model features its effectiveness in accounting for multiple types of evacuation vehicles, the interdependent relations between pedestrian and vehicle flows via some conversion locations, and the inevitable conflicts between intersection turning vehicle and pedestrian flows. An illustrating example concerning an evacuation around the M&T stadium area has been presented, and the results indicate the promising properties of our proposed model, especially on reflecting the complex interactions between vehicle and pedestrian flows and the favorable use of high-occupancy vehicles for evacuation operations.     

基于模拟退火算法的供应链管理分析

随着经济全球化的到来,更多的企业将工作重心放在其核心竞争力上,而物流业务也逐渐从生产加工等业务中分离出来。因此,如何有效管理供应商和生产商之间的关系(即供应链管理)已成为当前企业竞争和收益的焦点。以往对于供应链模型的求解往往是基于遗传算法等,虽然成熟有效,但局部搜索能力较差并且计算时间较长。主要应用模拟退火算法对供应链模型的求解问题进行研究和分析,并结合例题说明其有效性。