浅析建筑工程施工管理中存在的问题与及预防

本文针对建筑工程施工管理中存在的设计问题、资金问题、材料问题、人员问题、管理体系问题及生态环境问题,分析了原因并提出了相应的对策和预防措施。     

钢渣混凝土研究现状分析

目前钢渣的综合利用已经成为一个热点问题,本文主要论述了钢渣在混凝土中的研究意义,具体阐述了钢渣混凝土的发展概况、研究现状及实际工程应用状况等问题,提出了复合掺合料配比及掺量问题、钢渣钝化问题、安定性不良问题、钢渣细度问题等在钢渣混凝土研究中亟待解决的问题,指明了钢渣混凝土的应用前景。     

针对桥梁施工中常见问题的处理

桥梁工程的质量问题、施工问题、裂缝问题以及其自身的养护问题都成为了当今制约我国道路桥梁质量与安全的首要问题之一。本文针对这些问题的处理措施进行了阐述。     

我国结构被动控制工程应用的几个问题

概述了目前结构被动控制发展的现状,讨论了我国结构被动控制工程应用所面临的几个问题,即：综合效益问题、设计问题、产业化问题和功能材料的应用问题。首先,通过分析表明,有控结构与无控结构相比具有明显的综合效益;随后,就设计问题、产业化问题和功能材料的应用问题指出了值得进一步研究的课题。     

关于现场施工管理在路桥工程中的应用探讨

本文对路桥项目施工现场管理中的技术问题、材料问题、机械问题、机械设备问题、人员管理问题、施工安全问题和资料管理问题六个方面进行了论述,共同行参考。     

聚酰亚胺在晶闸管芯片台面保护上的应用分析

本文简要介绍了晶闸管和聚酰亚胺,对不同厂家聚酰亚胺应用V-I特性进行了比较,详细叙述了涂覆方法及固化工艺,分析了使用过程中粘附性问题、适应有机溶剂和灌封胶的问题、交流阻断问题、芯片长期存放稳定性问题、重点分析了产生蠕变的现象和原因,最后提出相应的解决方法。     

用工业工程思想发现、解决和预防问题

在工厂现场问题研究的基础上,联系生活实际,对问题科学进行了研究.定义了什么叫问题;探讨了问题的本质;对工作生活中问题进行了分类;阐明了问题和风险以及问题和矛盾之间的关系.利用工业工程(IE)的思想,分析了普遍的如何发现问题及解决问题的思维过程;阐明了在工作和生活中如何利用问题的实质去发现问题,并最终解决和预防问题.报告了解决问题的三个原则、注意事项和步骤.     

矿区供电系统继电保护问题探讨

本文主要阐述了矿区供电系统继电保护的上下级保护配合问题、二次回路接线错误、保护选型问题、速断保护问题、线路中配电变励磁涌流问题、正确配备继电保护装置、继电保护的定期检查等问题。     

问题导向教学在国际经济学教学中的应用

问题导向教学是研究性教学的重要方法之一。本文探讨了在国际经济学教学中实施问题导向教学法的可行性,以及问题设置、问题探索、成果展示与交流和评价与总结等问题导向教学的具体实践环节。最后提出了问题导向教学法应用的几点思考。     

浅谈二灰稳定碎石施工存在问题及解决方法

结合东盟营造陕西风永高速公路施工的石灰粉煤灰问题碎石基层施工，阐述了二灰碎石施工中经常遇见的鼓包问题、室内强度问题、含水量控制问题、光面问题、配合比优化问题及现场平整度控制问题的形成原因及解决方法。     

An exact penalty function method for optimising QAP formulation in facility layout problem

A quadratic assignment problem (QAP), which is a combinatorial optimisation problem, is developed to model the problem of locating facilities with material flows between them. The aim of solving the QAP formulation for a facility layout problem (FLP) is to increase a system’s operating efficiency by reducing material handling costs, which can be measured by interdepartmental distances and flows. The QAP-formulated FLP can be viewed as a discrete optimisation problem, where the quadratic objective function is optimised with respect to discrete decision variables subject to linear equality constraints. The conventional approach for solving this discrete optimisation problem is to use the linearisation of the quadratic objective function whereby additional discrete variables and constraints are introduced. The adoption of the linearisation process can result in a significantly increased number of variables and constraints; solving the resulting problem can therefore be challenging. In this paper, a new approach is introduced to solve this discrete optimisation problem. First, the discrete optimisation problem is transformed into an equivalent nonlinear optimisation problem involving only continuous decision variables by introducing quadratic inequality constraints. The number of variables, however, remains the same as the original problem. Then, an exact penalty function method is applied to convert this transformed continuous optimisation problem into an unconstrained continuous optimisation problem. An improved backtracking search algorithm is then developed to solve the unconstrained optimisation problem. Numerical computation results demonstrate the effectiveness of the proposed new approach.     

Stress intensity solutions for the interaction between a hole edge crack and a line crack

The principle of superposition is used to solve the problem and the original problem is converted into two particular hole edge crack problems. The remote stresses are applied at infinity in the first problem. Meantime, a dislocation distribution is assumed outside the hole contour in the second problem. Singular integral equation is proposed for the solution of the second problem, in which the right hand side of the integral equation is obtained from the solution of the first problem. The first problem as well as the elementary solution of the second problem are solved by means of the rational mapping approach. Finally, numerical examples with the calculated results of stress intensity factors are presented.     

供应链中生产和运输协调调度问题初探

提出了解决供应链中生产和航空运输协调调度问题的理论框架.基于对生产调度和航空运输调度彼此制约关系的分析,协调调度问题被分解为两个子调度问题.建立了航空运输子调度问题的整数规划模型,并证明了该问题为NP完全问题.提出了基于倒排调度方法(backward scheduling method)的调度算法解单机生产调度子问题.     

A SINGULAR-ARC APPROXIMATION TO A DYNAMIC SAILPLANE FLIGHT PATH OPTIMIZATION PROBLEM

A dynamic sailplane performance problem is investigated using optimal control theory. The problem is to minimize the total flight time between successive thermals subject to zero altitude loss. From the original nonlinear optimal control problem, a singular linear/quadratic problem is derived and solved.

A relationship between the original optimal control problem and a certain parameter optimization problem is explored, and it is shown that the solution to this parameter optimization provides a lower bound for the minimum flight time of the original optimal control problem. The parameter optimization solution is adopted as the reference trajectory for the linear/quadratic problem. Finally, the linear/quadratic problem is shown to provide a good approximation to the original optimal control problem at a small fraction of the computing cost.     

Balancing transfer lines using Benders decomposition and ant colony optimisation techniques

In this paper, we investigate a transfer line balancing problem in order to find the line configuration that minimises the non-productive time. The problem is defined at an auto manufacturing company where the cylinder head is manufactured. Technological restrictions among design features and manufacturing operations are taken into consideration. The problem is represented by an integer programming model that assigns design features and cutting tools to machining stations, and specifies the number of machines and production sequence in each station. Three algorithms are developed to efficiently solve the problem under study. The first algorithm uses Benders decomposition approach that decomposes the proposed model into an assignment problem and a sequencing problem. The second algorithm is a hybrid algorithm that mixes Benders decomposition approach with the ant colony optimisation technique. The third algorithm solves the problem using two nested ant colonies. Using 15 different problem dimensions, we compare results of the three algorithms in a computational study. The first algorithm finds optimal solutions of small problem instances only. Second and third algorithms demonstrate optimality gaps less than 4.04 and 3.8%, respectively, when compared to the optimal results given by the first algorithm. Moreover, the second and third algorithms are very promising in solving medium and large-scale problem instances.     

Surrogated Linear Programming

This paper deals with the development of a completely different technique for solving the linear programming (LP) problem. The general LP problem is replaced by an LP problem having a single constraint called the surrogated linear programming (SLP) problem. The SLP problem retains the same objective function, but is constrained by a convex combination of the original constraints. A special equivalency relationship is derived between the general problem and the surrogated problem in route to the final computational algorithm. The technique is not subject to round off error propagation and has promise for savings in computation time.     

A nested column generation algorithm to the meta slab allocation problem in the steel making industry

This paper addresses one of the key operational decision problems in the steel industry which is related to the allocation of orders to stock materials in the surplus inventory. The meta slab allocation problem can be stated as the ‘multi-stage multiple knapsack problem’ where the problem is to design slabs using orders with similar properties (the first stage) and allocating these designed slabs into the existing meta slabs in the inventory yard (the second stage). The objective of the problem is to maximise the allocated order weights in slabs and meta slabs. For the given problem, we propose a column generation algorithm, where a column in the master problem represents meta slabs and the sub problem is to design ‘bins’, here slabs with the given orders. The sub problem itself also becomes a multiple knapsack problem and we proposed a practical set-partitioning heuristic. The proposed algorithm was tested with daily operation data given from an integrated steel company in the Asia Pacific. The computational results showed that the proposed heuristic solved the real instances pretty well. The proposed algorithm was successfully deployed to the integrated steel mill.     

基于遗传算法的高校教室调度问题

对高校教室调度问题进行研究,能使教室和课程达到一种合理的优化配置。类似问题的研究在制造业或生产系统中都占有非常重要的地位。研究首先采用三元组方式,将教室调度问题描述为一类具有机器适用限制的并行多机问题,以最小化Cmax（即集中时间提高教室利用效率）和滞后时间总和为调度目标,建立了对应的数学模型。根据问题的特性,设计了包含分派规则和遗传算法的启发式调度算法求解该类问题。研究结合问题特性在编码,个体适应度函数,交叉及变异等方面进行了设计。以实例分析验证了所设计算法的可行性和有效性。     

基于TRIZ理论的套袋机套袋装置优化设计

目的解决现有套袋机套袋装置在套袋过程中薄膜内袋容易产生折角的问题。方法利用TRZI理论中功能模型及因果链分析对初始问题进行全面分析,找到根本问题后,再将根本问题转化为TRIZ问题模型,然后利用TRIZ中解决问题的工具找到多个解决方案模型,并对方案模型进行可用性评估。结果将评估所得的最优方案进行实施,薄膜内袋折角的问题被解决,双层袋合格率达到99.5%。结论利用TRIZ理论中的一系列工具对薄膜内袋折角问题进行转化,建立了解决方案模型,选取了最优方案进行实施,成功解决了薄膜内袋折角问题。     

Iterated beam search for the combined car sequencing and level scheduling problem

The level scheduling problem is concerned with the final stage of a multi-stage just-in-time production system so that different models of a product are evenly distributed in a discrete production sequence, thereby making the problem practically an unconstrained optimisation problem. The car sequencing problem, on the other hand, is a constraint satisfaction problem based on a number of options constricting the final assembly schedule. The combined car sequencing and level scheduling problem aims to find the optimal production schedule that evenly distributes different models over the planning horizon and satisfies all option constraints. This paper proposes a parametric iterated beam search algorithm for the combined problem that can be used either as a heuristic or as an exact optimisation method. The paper includes a computational study based on a 54-instance test bed that proves the effectiveness of the proposed algorithm.