中国城市土地利用效率的动态测度及影响因素——基于DEA-Tobit两步法的分析

利用数据包络模型(DEA)对中国大陆30个省、市、自治区2001—2010年城市土地利用效率进行了测度与评价,并运用Tobit回归模型对其影响因素进行了深入分析.结果表明:①中国城市土地利用效率总体呈现上升趋势,除少数省区效率值低于0.5以外,其余均保持在0.5-1之间;②城市土地利用效率前沿面分析结果显示,2001—2010年处于生产前沿面的省、市、自治区的数量保持稳定,但其空间分布却发生了一些变化,10年间东部地区减少2个,西部地区增加2个,中部地区一直处于零水平的状态;③城市土地利用过程中高投入低产出局面的扭转、非农从业人员效率的提高是城市土地利用效率改善的基本内核和关键所在;④经济规模对城市士地利用效率呈现正向促进作用,低层次的产业结构和不断增加的人口密度呈现负面影响,政府规制、空间集聚水平、城市规模和区位条件的影响并不显著.     

单一成本目标数据处理服务外包业务工艺规划研究

本文对数据处理服务外包业务工艺规划所涉及的要素——成品数据要求、工艺方法、工序排序和设备工具进行了分析,结合数据处理业务流程特点,采用数学规划方法建立了非线性优化模型。在综合比较各类求解非线性规划的方法的基础上,鉴于遗传算法具有编码容易、搜索速度快以及鲁棒性等优点,选择遗传算法求解单目标优化问题。通过选取实际企业数据,利用MATLAB编程求解,验证了本文结果的适用性。     

Modelling maintenance practice of production plant using the delay-time concept

In this paper we present a study carried out for a copper productsmanufacturing company, developing and applying the delay-timemodelling technique to model and thus optimize preventive maintenance(PM) of the plant. A key machine in the plant is used to illustratethe modelling process and management reaction. The parameter values of the process by which faults arise andof the delay-time distribution are estimated from maintenancerecord data of failures and faults found at PM, using the methodof maximum likelihood. A test of the model fit to data is carriedout. Based upon the estimated model parameters and the failuredelay time, an inspection model is proposed to describe therelationship between the total downtime and the PM interval.     

Issues with the Smith–Wilson method

We analyse various features of the Smith–Wilson method used for discounting under the EU regulation Solvency II, with special attention to hedging. In particular, we show that all key rate duration hedges of liabilities beyond the Last Liquid Point will be peculiar. Moreover, we show that there is a connection between the occurrence of negative discount factors and singularities in the convergence criterion used to calibrate the model. The main tool used for analysing hedges is a novel stochastic representation of the Smith–Wilson method.     

市场机制和政府监管下新能源汽车产业合作创新演化博弈研究

节能和新能源汽车是解决能源、气候和环境问题的关键措施,越来越受各国政府的重视。本文基于演化博弈理论,从市场机制和政府监管两个方面分析了政产学研新能源汽车合作创新行为,首先通过建立博弈模型观察多个利益相关者的合作创新行为;再根据复制动态方程和演化稳定策略分析影响合作创新活动的动力因素。为验证理论计算的有效性进行了数值仿真,结果表明:在市场机制下政府补贴、违约金和收益分配系数对企业和学研机构开展新能源汽车合作创新的驱动效果明显,但作用机制不同;在政府监管下合理税率、行政处罚有利于促进新能源汽车合作创新的稳定性。此外,在新能源汽车合作过程中获得了额外的社会收益,这将增加政府参与新能源汽车合作创新活动的积极性,研究结果可以指导政产学研未来更好的决策。     

六西格玛在F半导体公司BGA产品质量改进的应用

BGA(Ball Grid Array球栅阵列封装)是一项被广泛应用的高密度封装技术。对BGA产品制造来说,过程中的最容易出现次品的环节是植球工序。本文采用六西格玛管理的DMAIC流程,通过控制胶量厚度和植球偏移量这两点对提高植球成功率最有影响的因素,对影响BGA产品制造过程中植球工序的设备能力进行了改进,取得良好的效果。     

粤东柘林湾浮游植物与生态因子的灰关联-回归分析

应用灰关联方法对 2 0 0 1年 1 0月至 2 0 0 2年 7月柘林湾海域的海水采样结果进行数据分析 ,在磷酸盐、硅酸盐等 1 1项生态因子中找出影响浮游植物密度的关键因子 .根据这个结果 ,进一步建立了以这些关键因子为自变量的线性回归模型 ,模型最后的分析结果和灰关联分析的结果一致 ,即 Fe、水温、浊度是影响柘林湾浮游植物密度的关键因子 .     

The delay-time modelling of preventive maintenance of plant given limited PM data and Selective repair at PM

This paper presents a maintenance-modelling case study of aplant manufacturing brake linings. A delay–time modelis developed and applied to model and optimize preventive maintenance(PM). A key subsystem in the plant is used to illustrate themodelling process and management reaction. Defects identifiedat PM may not all be removed. This incomplete response to PMis a feature which has not been modelled before. The parametervalues of the delay-time process are estimated from objectivedata from maintenance records of failures, using the methodof maximum likelihood. This is aided by a theorem extendingresults on the NHPP arival rate of failures in a perfect-inspectioncase to the non-perfect-inspection case. Problems of parameterestimation given inadequate data collected at PMs are discussed,and the necessity to augment objective data with subjectiveassessments highlighted. Based upon the estimated model parametersand delay-time distribution, an inspection model is constructedto describe the relationship between the total unit downtimeand the PM interval. The response of management is discussed.     

EPC项目关键链缓冲区设置模型研究

为有效解决EPC项目关键链缓冲区时间估计不够准确而影响项目进度计划编制与控制的问题,在分析现有关键链缓冲区设置方面研究成果及其存在不足基础上,首先采用探索性因子分析法,通过文献归纳、问卷设计与数据采集、数据处理与分析,进行了EPC项目缓冲区设置影响因素发掘与提取,提取出了21项EPC项目缓冲区设置关键影响因素;其次建立了基于影响因素权重及其对不同工序影响程度的工序综合权重计算模型,同时引入工序位置权重及工序作业时间风险弹性系数,构建了项目缓冲区及输入缓冲区定量确定模型;最后以某EPC项目为例进行了应用研究,论证了关键链缓冲区设置模型的准确性与可操作性,为EPC项目缓冲区设置提供了借鉴。     

A matrix-analytic solution for the DBMAP/PH/1 priority queue

Priority queueing models have been commonly used in telecommunication systems. The development of analytically tractable models to determine their performance is vitally important. The discrete time batch Markovian arrival process (DBMAP) has been widely used to model the source behavior of data traffic, while phase-type (PH) distribution has been extensively applied to model the service time. This paper focuses on the computation of the DBMAP/PH/1 queueing system with priorities, in which the arrival process is considered to be a DBMAP with two priority levels and the service time obeys a discrete PH distribution. Such a queueing model has potential in performance evaluation of computer networks such as video transmission over wireless networks and priority scheduling in ATM or TDMA networks. Based on matrix-analytic methods, we develop computation algorithms for obtaining the stationary distribution of the system numbers and further deriving the key performance indices of the DBMAP/PH/1 priority queue. AMS subject classifications: 60K25 · 90B22 · 68M20 The work was supported in part by grants from RGC under the contracts HKUST6104/04E, HKUST6275/04E and HKUST6165/05E, a grant from NSFC/RGC under the contract N_HKUST605/02, a grant from NSF China under the contract 60429202.     

应急物资联合配送决策研究

救援物资的高效投放是应急物流的关键活动之一。考虑到灾后救援车辆短缺,分配时受灾群众产生非理性心理,以及灾后道路状况对军、地救灾车辆速度产生影响等因素,本文从军民融合的角度出发,根据军地运输车辆特点,设计科学合理的车辆分配方案与运输路线。论文研究构建了基于车辆分配公平性和应急配送及时性的“分配-运输”集成决策模型,设计改进后的NSGA-Ⅱ算法进行求解,最后通过算例验证本算法的有效性和合理性,并通过调节军民运输车辆数,找到应急救援过程中的最佳军、地车辆比例,从而为灾后各灾备中心的车辆调度决策提供参考。     

估计感度分布中位数的两阶段优化序贯试验设计方法研究

感度试验在爆炸科学领域有非常广泛的应用,其中位数是含能材料的一个关键性能指标.高效估计感度分布中位数是实际工程应用中的重要问题.文章提出一种两阶段的优化序贯试验设计方法来估计感度分布的中位数,并将正交设计与两阶段优化序贯试验设计方法相结合给出了筛选影响含能材料安定性重要因子的试验设计方法.广泛的模拟比较验证了所提方法在小样本情况下可以获得感度分布中位数的准确估计,并且对模型假设和初始参数猜测具有一定的稳健性.当因子效应不是太小的时候,因子筛选方法可以准确地筛选出有显著影响的因子.     

基于FNP-ADC模型的弹药调度系统保障效能评估

正确评估诸如弹药调度系统此类复杂武器装备的系统效能,可为作战指挥决策提供重要支撑依据,从装备系统结构组成及复杂性出发,合理地表示工作状态及其转移过程,在流水网络计划(flow network planning,FNP)技术框架下应用ADC模型开展效能评估.以FNP时间参数为基础,确定了组成分系统故障一般概率分布下的可用性、可信性和保障能力表示方法,分别表示为影响因素的函数关系,最终建立了FNP-ADC模型.综合进行保障效能评估,可进一步分析因素对效能的影响程度,并给出了案例分析.     

受时间限制的运输问题的新算法

针对现实的物品配送过程中存在着各种各样的外界因素会导致销售时间上的不可预测性的问题,本文在常用的解决受时间限制运输问题的模型的基础上,提出了一种新的解决模型。新模型更适用于较为苛刻的调运时间,相比已有的模型更精确、更适用于现实的市场环境。文中举例说明了该模型的有效性。     

基于网格化管理视角下灾后应急物流决策模型与算法研究

灾害发生后,应急资源的需求预测与应急配送中心的合理选址是实现高效救援的关键。本文通过在网格化管理视角下的信息更新将应急救援过程划分为多个阶段,在开展救援的过程中实现救援信息收集和救援预测的同步开展,建立一种多阶段带时间约束的应急救援物资配送响应-时效性的选址模型。借助遗传算法(NSGA-II),实现了基于编码结构独立、路径相互关联基础上的多目标规划求解。本研究的决策模型及算法有着较好的搜索与寻优能力,对实际救援开展具有指导意义。     

基于PLSR的多级制造过程关键质量特性识别方法

为解决多级制造过程关键质量特性识别中多质量特性之间的相关性问题,将偏最小二乘回归方法(Partial Least Squares Regression, PLSR)引入模型构建与分析中。首先应用状态空间方法建立多级制造过程关键质量特性识别模型,进而利用PLSR方法解决质量特性间的多重共线性问题并进行模型分析,识别关键质量特性,最后以卷烟生产过程为例介绍了该方法的应用。实例表明,该方法不仅可以有效识别多级制造过程关键质量特性,而且能够建立各级过程的输出质量对最终产品质量的影响及其质量特性之间相互关系的模型,反映多级生产过程的结构特征和各级过程质量特性之间的因果关系,为多级制造过程质量分析与控制提供依据。     

煤矿安全生产法律法规实效性的(安全作用)虚拟变量模型分析

为了弄清我国煤矿安全生产因素对安全生产的影响程度,建立了百万吨煤死亡率与影响煤矿安全生产五个主要指标(采煤机械化程度、煤矿工程技术人员配备率、全国人均GDP、原煤生产全员工效和吨煤基本建设投入)之间的多元回归模型,结果显示采煤机械化程度、吨煤基本建设投入和全国人均GDP对百万吨煤死亡率有着较大影响,其中全国人均GDP对百万吨煤死亡率起着负的作用.为了比较分析20世纪90年代以来有关煤矿安全生产的一些重要法律的法律法规实效性的安全作用的方向和大小,建立了多元虚拟变量回归模型,研究表明,有关煤矿安全生产的"三法律一条例"实效性的安全作用平均使得百万吨煤死亡率降低0.895人;"三法律一条例"的实效性表明,法律条款中的经济处罚和制裁条款与经济发展水平越符合,法治力度越强,其执行效果越好.     

Cryptography using multiple one-dimensional chaotic maps

Recently, Pareek et al. [Phys. Lett. A 309 (2003) 75] have developed a symmetric key block cipher algorithm using a one-dimensional chaotic map. In this paper, we propose a symmetric key block cipher algorithm in which multiple one-dimensional chaotic maps are used instead of a one-dimensional chaotic map. However, we also use an external secret key of variable length (maximum 128-bits) as used by Pareek et al. In the present cryptosystem, plaintext is divided into groups of variable length (i.e. number of blocks in each group is different) and these are encrypted sequentially by using randomly chosen chaotic map from a set of chaotic maps. For block-by-block encryption of variable length group, number of iterations and initial condition for the chaotic maps depend on the randomly chosen session key and encryption of previous block of plaintext, respectively. The whole process of encryption/decryption is governed by two dynamic tables, which are updated time to time during the encryption/decryption process. Simulation results show that the proposed cryptosystem requires less time to encrypt the plaintext as compared to the existing chaotic cryptosystems and further produces the ciphertext having flat distribution of same size as the plaintext.     

MODELING A RIGHTS‐BASED APPROACH FOR MANAGING HABITAT IMPACTS OF FISHERIES

ABSTRACT. Limiting adverse consequences of fishing on essential fish habitat has emerged as a key fishery management objective. The conventional approach to providing habitat protection is to create MPAs or marine reserves that prohibit all or certain types of fishing in specific areas. However, there may be more cost‐effective and flexible ways to provide habitat protection. We propose an individual habitat quota (IHQ) system for habitat conservation that would utilize economic incentives to achieve habitat conservation goals cost‐effectively. Individual quotas of habitat impact units (HIU) would be distributed to fishers with an aggregate quota set to maintain a target habitat “stock.” HIU use would be based on a proxy for marginal habitat damage. We use a dynamic, explicitly spatial fishery and habitat simulation model to explore how such a system might work. We examine how outcomes are affected by spatial heterogeneity in the fishery and the scale of habitat regulation. We find that the IHQ system is a highly cost‐effective means of ensuring a given level of habitat protection, but that spatial heterogeneity and the scale of regulation can have significant effects on the distribution of habitat protection.