基于子网络的项目群工期延误惩罚模型研究

针对现有项目群工期延误惩罚模型较少研究工期延误产生的局部与整体效应,通过引入项目群的子网络,构建了基于子网络的项目群结构。在此基础上,采用关键路径方法(CPM),分别研究了因承包人原因导致的子网络之间和子网络内项目工期延误对项目群所带来的影响,并构建了基于子网络的项目群工期延误惩罚模型。结合Z项目群,对子网络之间和子网络内的工期延误惩罚模型进行了实例分析。     

项目组合网络实证研究

将复杂网络理论引入到项目组合管理中,以项目为节点,以项目之间的依赖关系为边,项目的成本看作点权,项目之间的依赖强度看作边权,将项目组合抽象为一个复杂加权网络。研究了4家企业的项目组合网络,在分析项目组合特性的基础上,概括了项目组合的复杂网络行为特征。对企业项目组合网络进行综合对比分析发现,项目组合网络具有如下相似特征:①节点度分布不同于其他社会网络,倾向于幂律分布,又有偏斜泊松分布的迹象;②度相关系数负相关,有别于其他社会网络;③具有集群结构;④聚集系数很大;⑤网络直径较小;⑥平均度数小于4。     

基于结构洞理论的城市复杂项目群组织优化研究

研究目的:从城市复杂项目群组织的复杂性着手,针对目前项目群组织管理和控制在实际应用中出现的问题,研究一种优化项目群组织的有效方法.研究过程:基于结构洞理论模型,通过分析城市复杂项目群组织结构的网络特性,找到项目群组织中各个关系人之间的结构洞,以此作为研究的对象来建立组织的优化模型,在确立目标函数的情况下,通过结构约束算法求取网络规模的密度约束,并通过最小二乘法进行有效的修正.研究结论:通过模型的构建,可以得出结构洞理论是研究城市复杂项目群组织关系的有效理论方法,为其组织优化提供了交互视角,有利于组织中关系人目标的实现.     

气候变化对国家脆弱性的影响

2014年联合国政府间气候变化专门委员会(IPCC)第5次评估报告指明气候变化对人类安全的影响.本文利用2004年Bowers提出的基于信息论的计算两个变量之间的不确定逻辑关系的U值方法,讨论气候指标对国家脆弱性指标是否存在影响,进而确定影响的同步或异步,并利用三次样条插值计算气候指标对国家脆弱性指标的影响力.最后利用国家经济指标和国家脆弱性增长速率确定了国家脆弱性临界点.     

城市CIS物理关联脆弱性的动态分析方法

本文以城市关键基础设施系统(Critical Infrastructure System, CIS)为研究对象,将关键基础设施之间组成的复杂物理网络划分为个体层面、中观层面和系统层面三种类型,从物理关联势差的角度分析了城市CIS内部物理关联机理。根据城市CIS物理关联特性,引入元胞自动机(Cellular Automata, CA),以一种物理资源为主导建立模型,采用“自底向上”的方法,从微观关键基础设施活动推出宏观城市CIS表现。选取元胞连通性、元胞正常状态变化率和传输效率作为脆弱性评估指标,估算不同时间点城市CIS脆弱性的动态变化,实现物理关联脆弱性的动态分析,并运用加权平均值作为一段时间内城市CIS脆弱值。最后,以S城市为例,对物理关联脆弱性动态分析方法的合理性和有效性进行验证,评估结果为城市CIS保护提供支持。     

一种构造群表示的新方法

群表示论是用来描述群的理论,是研究群的最有力的工具之一,而构造表示是表示论的基本任务之一.本文给出一种从已知线性空间构造新的线性空间的新方法.利用这种新方法,我们得到一种新的途径,从一个给定的群表示得到一个同一个群新的表示.     

广义优先关系约束下Max-npv项目调度问题及其遗传算法

以往Max-npv项目调度问题的研究都假定活动之间的关系为单一结束-开始类型,现实中活动之间关系复杂多变,因此,将广义优先关系引入Max-npv项目调度问题中,构建了广义优先关系约束下的Max-npv项目调度模型。针对该优化模型设计了一种双层遗传算法,外层遗传算法负责任务执行模式的优化,内层遗传算法负责任务调度的优化。在内层遗传算法中,采用任务开始时间之差作为新的编码方式,大大简化了交叉变异算子,针对网络图中的环状结构设计了修复算子,确保了编码的有效性。通过一个算例对算法进行了测试,实验结果验证了算法的有效性。     

灰色白化权函数定权聚类模型在合并村庄脆弱性评估中的应用北大核心

灰色白化权函数定权聚类模型是根据灰色关联矩阵或灰数的白化权函数值将一些意义、量纲、样本值数量相差较大的观测指标或观测对象划分成若干个可定义类别的方法。文中利用灰色白化权函数定权聚类模型数理意义与合并村庄脆弱性评估目标高度契合的技术特点,运用该模型从外部扰动、敏感性、适应力三个维度对研究区域内8个合并村庄进行脆弱性评估,完善地解决合并村庄脆弱性评估时多维度、多评估对象、多评估指标、多评估等级交织在一起的复杂问题,从而为合并村庄的可持续发展提供决策与参考。     

基于广义线性模型的水稻种植风险评估

农作物风险评估是农业风险管理的前提与基础.为探索科学有效的水稻种植风险评估模型,将水稻种植风险评估过程分为承灾体脆弱性评估和致灾因子危险性评估两个过程,利用广义线性模型解决自然灾害会对水稻产量造成多大程度的损失问题,在产量波动服从布尔分布的假设下,建立起致灾因子(用连续降雨天数、连续低温天数等指标表示)与产量波动之间的线性关系,完成承灾体脆弱性评估;利用天气发生器模型模拟各地区致灾因子发生情况解决自然灾害概率分布的问题,完成致灾因子危险性评估;最终给出风险评估的量化表达.通过黑龙江农垦气象及水稻产量数据的实证分析验证了模型的有效性,并讨论了该模型在保险费率厘定方面的应用.     

基于前景理论和灰色关联的群决策评估模型

构建了基于前景理论和灰色关联的国防科研项目运行阶段群决策评估模型.基于群层次分析法确定评估指标权重,采用前景理论描述专家心理期望行为,以各项目的属性均值序列为参考方案,建立各项目与参考方案间的关联系数,并以此构建基于关联系数的价值函数,根据各项目的综合前景价值对国防科研项目运行阶段的各评估项目进行择优排序.实例表明了方法的客观合理性和有效性.     

Minimizing the total weighted late work in scheduling of identical parallel processors with communication delays

This paper addresses a certain type of scheduling problem that arises when a parallel computation is to be executed on a set of identical parallel processors. It is assumed that if two precedence-related tasks are processed on two different processors, due to the information transferring, there will be a task-dependent communication delay between them. For each task, a processing time, a due date and a weight is given while the goal is to minimize the total weighted late work. An integer linear mathematical programming model and a branch-and-bound algorithm have been developed for the proposed problem. Comparing the results obtained by the proposed branch-and-bound algorithm with those obtained by CPLEX, indicates the effectiveness of the method.     

Distributed scheduling using simple learning machines

A new approach to develop parallel and distributed algorithms of scheduling tasks in parallel computers is proposed. A game theoretical model with the use of genetic-algorithms based learning machines called classifier systems as players in a game, serves as a theoretical framework of the approach. Experimental study of such a system shows its self-organizing features and the ability of collective behaviour. Following this approach a parallel and distributed scheduler is described. A simple version of the proposed scheduler has been implemented. Results of the experimental study of the scheduler demonstrate its high performance.     

Evaluación sísmica de los edificios de mampostería típicos de Barcelona aplicando la metodología Risk-UE

In this work, a study about the vulnerability and seismic damage of unreinforced masonry buildings is carried out. Three models of buildings representatives of the Eixample district of Barcelona have been chosen. The seismic vulnerability is evaluated by means of the Risk-UE methodology. The seismic demand is described by elastic project spectrum, in this case, defined by the Eurocode 8. Fragility curves are obtained from a nonlinear analysis, considering the capacity spectra. Expected seismic damage is gotten with the damage probability matrices, which indicate the occurrence probability of a damage state for a seismic demand given. The analysis of the buildings has been performed by TreMuri program by means of a macroelements model, which represents of a whole masonry panel. The buildings, here, analyzed are real and detailed structural drawings and reports have been used to model them. The results shown a considerable vulnerability in this type of buildings, therefore, in spite of the seismic hazard the expected seismic risk is significant.     

A Parallel Projection for the Multicommodity Network Model

We present an application of parallel computing techniques to the solution of a quadratic programme that arises in the resource-directive decomposition method for multicommodity problems. A sequential algorithm for the quadratic programme is discussed, and its extension to a parallel implementation is given. Computational testing of the sequential and parallel algorithms was done on the Sequent Symmetry S81 parallel computer located in the Parallel Processing Laboratory at Southern Methodist University. On several large test problems the parallel version achieved a speed-up of 10 with 12 processors.     

Reliability-centred maintenance analysis for a complex military system

The preventive-maintenance (PM) programme is a very importantdocument in the life cycle of a piece of equipment or system.The traditional method used within China to determine PM programmeshas many disadvantages, and some tasks in old programmes haveproved to be unnecessary. Through analysing a complex militarysystem (X system) by means of the reliability-centred maintenance(RCM) analysis, it is found that RCM analysis is more successfulthan the traditional method in deciding the PM programme. Thenew PM programme does not include unnecessary PM tasks includedin the old programme. Thus the performance of the X system isenhanced, because the cost is reduced without compromising availability.It is believed that RCM analysis in military industry will makea valuable contribution to the maintenance of weapon systemsand equipment.     

Optimal Control of a Stochastic Assembly Production Line

The system under consideration comprises n workstations in parallel and one assembly workstation. The workstations are either reliable or unreliable and the product demand is random. The n different type parts are processed first in the parallel workstations and then are joined in the assembly workstation. By minimizing the expected discounted cost, it is shown that the optimal control policy is of the bang–bang type and can be described by a set of switching manifolds. The structural properties of the optimal policy, such as monotonicity and asymptotic behavior, are investigated. These structural properties are very useful to find the optimal policy in large-size systems. Three numerical examples are given to demonstrate the results.     

Delay asymptotics and bounds for multitask parallel jobs

Queueing Systems - We study delay of jobs that consist of multiple parallel tasks, which is a critical performance metric in a wide range of applications such as data file retrieval in coded...     

Optimal structural design of a planar parallel platform for machining

Parallel manipulators have many advantages over traditional serial manipulators. These advantages include high accuracy, high stiffness and high load-to-weight ratio, which make parallel manipulators ideal for machining operations where high accuracy is required to meet the requirements that modern standards demand.Recently, the finite element method has been used by some workers to determine the stiffness of spatial manipulators. These models are mainly used to verify stiffness predicted using kinematic equations, and are restricted to relatively simple truss-like models. In this study, state-of-the-art finite elements are used to determine the out of plane stiffness for parallel manipulators. Euler–Bernoulli beam elements and flat shell elements with drilling degrees of freedom are used to model the platform assembly.The main objective of this study is to quantify the stiffness, particularly the out of plane stiffness, of a planar parallel platform to be used for machining operations. The aim is to obtain a design that is able to carry out machining operations to an accuracy of 10 μm for a given tool force.Reducing the weight of a parallel manipulator used in machining applications has many advantages, e.g. increased maneuverability, resulting in faster material removal rates. Therefore the resulting proposed design is optimized with respect to weight, subject to displacement and stress constraints to ensure feasible stiffness and structural integrity. The optimization is carried out by means of two gradient-based methods, namely LFOPC and Dynamic-Q.     

Application of modal analysis in assessing attack vulnerability of complex networks

In this paper we propose an alternative way to study robustness and vulnerability of complex networks, applying a modal analysis. The modal weights of the network nodes are considered as a measure for their busyness, which is further used for preferential removal of nodes and attack simulation. Analyses of the attack vulnerability are carried out for several generic graphs, generated according to ER and BA algorithms, as well as for some examples of manmade networks. It was found that a modal weight based attack causes significant disintegration of manmade networks by removing a small fraction of the busiest nodes, comparable to the one based on the node degree and betweenness centrality.     

论并行算法的分类

§1.引言利用并行计算系统求解数值计算问题或非数值计算问题,需根据系统的类型设计并行算法。自然,并行算法设计的主要基础是求解问题所涉及的学科领域中的原理和方法,或直接揭示某些已有方法中潜在的并行性,或推广某些原理发展显含并行性的新方法。但是,要建立可行(能在一个并行计算系统中实现)和有效(能充分发挥系统性能使并行度与