喷雾器喷头工艺优化模拟

本文利用moldflow软件优化喷雾器喷头,得到合理、可靠的注射工艺参素,优化模具结构。     

基于模糊综合评价法的市郊铁路客运站选址研究

本文针对其特点,应用层次分析法建立市郊铁路客运站站址比选的指标体系,确定各指标的权重,结合模糊综合评价原理建立相应的站址方案评价模型,并给出算例分析,为市郊铁路客运站站址方案的比选提供了一种更科学、更符合实际的方法。     

基于结构熵的航空应急救援能力体系评价研究

根据航空应急救援的特点及要求,构建了综合一体化的航空应急救援能力体系,并运用结构熵理论对航空应急救援能力体系的结构有序度进行了评价,提出了相对优化方案。结合算例验证了该方法的可行性。     

高压输电线路故障测距算法综述

高压输电线路故障定位的准确性对电网的稳定运行有着非常重要的意义。文章对高压输电线路现有的各种测距方法进行了归纳总结和研究分析,并评述了各自的优点和不足。     

基于熵的能源结构和低碳模式优化研究

随着经济增长对能源需求的增加,能源结构越来越受到重视,碳排放成为各能源行业的重要指标,本文试图从熵及负熵理论角度分析我国进行能源结构调整的必要性,以及低碳模式对中国经济发展的促进作用。     

江苏省城市土地集约水平时空差异研究

城市土地集约利用是城市可持续发展的必然要求。根据江苏省城市土地集约利用现状及特点,从土地投入水平、土地利用程度、土地产出水平和土地生态效益四个方面建立了城市土地集约利用水平评价指标体系,运用基于熵值法的多因素综合评价方法对2005～2009年间江苏省13个地级城市土地集约利用水平进行时空差异分析,得出结论:(1)从时间变化特征上看,2005～2009年间江苏省城市土地利用集约度呈现总体上升趋势,但各地区之间存在差异;(2)从空间变化特征上看,由于受区位因素及产业结构等因素的影响,江苏省城市土地集约利用水平由南向北呈现明显的空间梯度差异,苏南地区的城市土地集约利用水平相对较高。最后根据影响因素的不同,有针对性地提出提高城市土地利用集约度的相应建议。     

企业选址中的区位粘性问题

绝大多数企业并没有遵循区位理论的指引,将企业选址在具有明显区位优势的地区,这个基本事实表明区位理论对企业选址的解释存在缺陷。文章试图从区位粘性的角度弥补理论缺陷,增加区位理论对企业选址的解释力度。文章在综述区位理论的基础上,从空间经济学的角度定义了区位粘性,采用路径依赖理论和网络嵌入性理论对区位粘性的内涵进行了深入剖析,结合出生于小城市的中国企业区位选址的实践分析了区位粘性的构成因素。研究结果发现非理性决策因素、商业模式的地域关联性、社会资源优势、集聚效应、洼地效应以及政治资源优势等六种因素构成了区位粘性的基本内涵,并形成了企业原址对企业的强大粘着力,对企业选址决策具有强烈的影响和作用,只有在外在的冲击力强到足以打破区位粘性时,企业才会做出再选址决策。     

Accommodating spatial correlation across choice alternatives in discrete choice models: an application to modeling residential location choice behavior

This paper presents a modeling methodology capable of accounting for spatial correlation across choice alternatives in discrete choice modeling applications. Many location choice (e.g., residential location, workplace location, destination location) modeling contexts involve choice sets where alternatives are spatially correlated with one another due to unobserved factors. In the presence of such spatial correlation, traditional discrete choice modeling methods that are often based on the assumption of independence among choice alternatives are not appropriate. In this paper, a Generalized Spatially Correlated Logit (GSCL) model that allows one to represent the degree of spatial correlation as a function of a multi-dimensional vector of attributes characterizing each pair of location choice alternatives is formulated and presented. The formulation of the GSCL model allows one to accommodate alternative correlation mechanisms rather than pre-imposing restrictive correlation assumptions on the location choice alternatives. The model is applied to the analysis of residential location choice behavior using a sample of households drawn from the 2000 San Francisco Bay Area Travel Survey (BATS) data set. Model estimation results obtained from the GSCL are compared against those obtained using the standard multinomial logit (MNL) model and the spatially correlated logit (SCL) model where only correlations across neighboring (or adjacent) alternatives are accommodated. Model findings suggest that there is significant spatial correlation across alternatives that do not share a common boundary, and that the GSCL offers the ability to more accurately capture spatial location choice behavior.     

Hub location problems in transportation networks

In this paper we propose a 4-index formulation for the uncapacitated multiple allocation hub location problem tailored for urban transport and liner shipping network design. This formulation is very tight and most of the tractable instances for MIP solvers are optimally solvable at the root node. While the existing state-of-the-art MIP solvers fail to solve even small size instances of problem, our accelerated and efficient primal (Benders) decomposition solves larger ones. In addition, a very efficient greedy heuristic, proven to be capable of obtaining high quality solutions, is proposed. We also introduce fixed cost values for Australian Post (AP) dataset.     

区位商视角下的深圳优势产业实证分析

深圳经济特区成立30年以来,经济快速发展的同时也面临各种挑战。一方面,深圳内部面临着发展后劲不足、调控经济不力等多方面的问题;另一方面,外部经受着国内产业结构不断优化升级的考验。运用区位商对深圳的产业优势进行数量上的分析,可以为深圳产业结构的调整和转型提供科学指导,加速深圳的产业结构升级,以促使深圳的经济能够跃上新的台阶。