KB-GA-Based Hybrid System for Layout Planning of Multistory Buildings

Layout planning of multistory buildings requires multidisciplinary participation in the decision-making process, which is governed by intuition, creativity, and experience of the designers, and available information. Optimization techniques are rarely applied to the layout planning stage. The present study aims at a hybrid approach by combining knowledge based system and a genetic algorithm (GA)-based optimization technique by employing them for suitable tasks, in order to take specific advantages of respective techniques, i.e., the domain dependent part is isolated and developed as a knowledge-based (KB) system, while the knowledge lean part is handled by the adaptive search techniques. The main issue to be addressed while developing an integrated system is to identify the role of individual approaches and the interactions among them. This paper outlines this concept through an integrated hybrid system GALOP for optimal layout planning of multistory office buildings. A multiobjective GA-based optimization technique produces a set of optimal solutions, from which a designer can select the final design.     

A methodology for optimally designing console panels for use by a single operator

A seven-step methodology is presented to determine a dimensionally correct optimal layout of a console panel for a single operator. This methodology integrates the steps in the layout design process and uses a mathematical optimization model from facility design to obtain the optimal panel layout. A major difference in this methodology from previous work is that the mathematical optimization model incorporates factors that are only partially included in previous mathematical models. In addition, it includes the areas of the panel components as a new factor. This methodology is illustrated by the design of a nuclear power plant console panel.     

总图运输设计在青岛钢厂改扩建中的作用

对工业企业老厂总图运输设计进行研究,归纳总结出老厂改扩建总图运输的设计的原则和方法,并通过青钢二炼钢厂工程实例,详细介绍老厂改造总图运输的特殊要求,以期对今后的工业企业技术改造工程提供最优设计方案。     

Particle Swarm Optimization-Supported Simulation for Construction Operations

This study proposes an integration of particle swarm optimization (PSO) and a construction simulation so as to determine efficiently the optimal resource combination for a construction operation. The particle-flying mechanism is utilized to guide the search process for the PSO-supported simulation optimization. A statistics method, i.e., multiple-comparison procedure, is adopted to compare the random output performances resulting from the stochastic simulation model so as to rank the alternatives (i.e., particle-represented resource combinations) during the search process. The indifference zone and confidence interval facilitate consideration of the secondary performance measure (e.g., productivity) when the main performance measures (e.g., cost) of the competing alternatives are close. The experimental analyses demonstrate the effectiveness and efficiency of the proposed simulation optimization. The study aims to providing an alternative combination of optimization methodology and general construction simulation by utilizing PSO and a statistics method so as to improve the efficiency of simulation in planning construction operations.     

城市规划理论在大型冶炼厂总图设计实践中的应用体现

叙述了广西防城港某大型冶炼厂的总体规划以及城市规划理论在冶炼厂总图布置中的应用,详细介绍了工厂与外部规划条件的衔接以及厂区内部的总图布置,为新建或搬迁的冶炼厂总图布置提供参考.     

Robust Optimal Design of Activated Sludge Bioreactors

This paper proposes an algorithm for a robust optimal design of the biological reactor and secondary settling facilities in suspended growth nitrogen and phosphorus removal systems. Robust optimization includes uncertainty in the decision-making procedure and seeks a solution that remains “close” to optimal for all potential operation scenarios. It thus differs fundamentally from the deterministic and stochastic approaches, where uncertainty is ignored or a solution based on either the most likely scenario or the average performance over all potential scenarios is produced. The robust optimization of a suspended growth system is a multiobjective optimization problem concerned with minimization of the global costs and variability of the system’s performance around the optimal. The proposed robust optimization approach uses the ASM3 model, making use of its performance prediction capabilities to produce a powerful tool for designing activated sludge systems. The algorithm was applied to the design of the biological reactor and secondary settling facilities for the Vila Real municipal wastewater treatment plant (Portugal).     

铸坯去向决策问题的建模与优化方法

 连铸-热轧界面的衔接、协调对于钢铁生产流程的高效、稳定运行有重要意义。针对连铸-热轧界面研究对于生产组织过程的简化处理而导致成果应用的局限性,提出一种以连铸出坯计划和热轧单元计划为对象,对实物铸坯的去向(加热炉、保温坑、板坯库)进行决策,并通过虚拟铸坯与实物铸坯的逐级匹配确定衔接方式(直接热装、热装、冷装)的优化方法。以热轧单元计划中直装和热装铸坯数最大化、直装和热装铸坯的传搁时间最小化为目标,考虑强制下线冷装要求、设备缓冲容量限制、实物铸坯-虚拟铸坯匹配规则、直装和热装铸坯传搁时间要求、铸坯上料必要运输时间等约束条件,建立了铸坯去向决策的整数非线性规划模型。设计了结合禁忌搜索的改进和声搜索算法求解模型,采用整数编码记录去向计划,通过模拟实物铸坯上料和虚拟铸坯匹配并装炉的过程进行解码,统计去向计划的目标函数值并计算评价值,利用禁忌搜索的局部寻优能力避免和声搜索早熟收敛,得到改进的和声搜索算法。以某钢铁企业热轧板带产线的生产数据进行测试,结果表明,铸坯去向决策模型可以提高直装率10.57%,提高热装率3.58%,直装和热装坯的传搁时间降低18.84%,并且改进和声搜索算法的最优评价值相比单一的禁忌搜索、和声搜索分别可以提升6.26%、4.51%,表明了模型和算法的有效性。     

Visualizing Search and Solution Spaces in the Optimum Design of Biaxial Columns

Optimum detailing of reinforcement bars for biaxial columns is a nontrivial task and there is no guidance in the codes of practice on this issue. Conventional methods of producing a single design solution and the use of optimization methods to find a single global optimum solution is not what practicing engineers require. This paper introduces an innovative approach to design, which emphasizes the interactive use of evolutionary computing in design and a new approach to visualization of search and solution spaces. This replaces the “black box” nature of the optimization techniques with an interactive approach in which the designer is in full control of the process. Instead of locating a single solution, clusters of good designs are identified in color, allowing the designer to conduct a more focused search in the areas of high performance design solutions. This method enables the designer to view individual solutions in the vicinity of the local peaks in order to learn more about the interrelationship between design parameters. Interactive visualization tools enable designers to develop a deeper understanding of the search and solution spaces and assist them in evaluating the merits of alternative designs and in their decision making. A by-product of visualization is knowledge discovery, which allows the designer to discover novel solutions that would not have been possible by conventional means. This approach could be easily extended to any stage of multidisciplinary design, especially to the conceptual stage of the design process. For example, the position of bars within a column is similar to the position of columns in a floor layout optimization problem.     

Optimum Concrete Mixture Proportion Based on a Database Considering Regional Characteristics

This paper presents an enhanced design methodology for optimal mixture proportion of concrete composition with respect to accuracy in the case of using prediction models based on a limited database. In proposed methodology, the search space is constrained as the domain defined by a limited database instead of constructing the database covering the region represented by the possible ranges of all variables in the input space. A model for defining the search space which is expressed by the effective region in this paper and evaluating whether a mix proportion is effective is added to the optimization process, yielding highly reliable results. To demonstrate the proposed methodology, a genetic algorithm, an artificial neural network, and a convex hull were adopted as an optimum technique, a prediction model for material properties, and an evaluation model for the effective region, respectively. And then, it was applied to an optimization problem wherein the minimum cost should be obtained under a given strength requirement. Experimental test results show that the mix proportion obtained from the proposed methodology considering the regional characteristics of the database is found to be more accurate and feasible than that obtained from a general optimum technique that does not consider this aspect.     

Decision Support System for Manufactured Housing Facility Layout

Productivity improvement of manufactured housing (MH) production systems has been a great concern to manufacturers and production managers. Studies show that a typical manufactured housing plant fails to produce at desired capacity and production rate because of several shortcomings. The evaluation of the production system efficiency in the factory is essential for meeting the growing demand of customers with respect to design and size of the housing product. It is imperative to explore alternative layout designs that would be more efficient and productive. A decision support system (DSS) is proposed to assist the user in selecting an efficient layout design matching specified requirements and business constraints. The DSS framework covers interrelated factors of: (1) the market demand; (2) MH organization; (3) MH production process; and (4) MH production planning and facility design. Existing MH factories can utilize simulation and optimization components of the DSS in streamlining their activities and locating then solving potential bottlenecks. Additionally, the DSS can be used in selecting optimal production system layout for new plant design.     

Modelling and design of cross-over trials

There are many diseases and conditions that can be studied using a cross-over clinical trial, where the subjects receive sequences of treatments. The treatments are then compared using the repeated measurements taken 'within' subjects. The actual plan or design of the trial is usually obtained by consulting a published table of designs or by applying relatively simple rules such as using all possible permutations of the treatments. However, there is a danger is this approach because the model assumed for the data when the tables or rules were constructed may not be appropriate for the new trial being planned. Also, there may be restrictions in the new trial on the number of treatment sequences that can be used or on the number of periods of treatment particular subjects can be given. Such restrictions may mean that a published design of the ideal size cannot be found unless compromises are made. A better approach is to make the design satisfy the objectives of the trial rather than vice versa. In this paper we describe an approach to constructing such tailor-made designs which we hope will lead to ill-fitting 'off the peg' designs being a thing of the past. We use a computer algorithm to search for optimal designs and illustrate it using a number of examples. The criterion of optimality used in this paper is A-optimality but our approach is not restricted to one particular criterion. The model used in the search for the optimal design is chosen to suit the nature of the trial at hand and as an example a variety of models for three treatments are considered. We also illustrate the construction of designs for the comparison of two active treatments and a placebo where it can be assumed that the carry-over effects of the active treatments are similar. Finally, we illustrate an augmentation of a design that could arise when the objectives of a trial change.     

Comparison of Using Mixed-Integer Programming and Genetic Algorithms for Construction Site Facility Layout Planning

The use of modular construction has gained wide acceptance in the industry. For a specific construction facility layout problem such as site precast standardized modular units, it requires the establishment of an on-site precast yard. Arranging the precast facilities within a construction site presents real challenge to site management. This complex task is further augmented with the involvement of several resources and different transport costs. A genetic algorithm (GA) model was developed for the search of a near-optimal layout solution. Another approach using mixed-integer programming (MIP) has been developed to generate optimal facility layout. These two approaches are applied to solve with an example in this paper to demonstrate that the solution quality of MIP outperforms that of GA. Further, another scenario with additional location constraints can also be solved readily by MIP, which, however, if modeled by GA, the solution process would be complicated. The study has highlighted that MIP can perform better than GA in site facility layout problems in which the site facilities and locations can be represented by a set of integer variables.     

Reliability-Based Optimal Design of Truss Structures Using Particle Swarm Optimization

In this work, the particle swarm optimization method is employed for the reliability-based optimal design of statically determinate truss structures. Particle swarm optimization is inspired by the social behavior of flocks (swarms) of birds and insects (particles). Every particle’s position represents a specific design. The algorithm searches the design space by adjusting the trajectories of the particles that comprise the swarm. These particles are attracted toward the positions of both their personal best solution and the best solution of the swarm in a stochastic manner. In typical structural optimization problems, safety is dealt with in a yes/no manner fulfilling the set of requirements imposed by codes of practice. Considering uncertainty for the problem parameters offers a measure to quantify safety. This measure provides a rational basis for the estimation of the reliability of the components and of the entire system. Incorporating the reliability into the structural optimization framework one can seek a reliability-based optimal design. For the problems examined herein, the reliability indexes of the structural elements are obtained from analytical expressions. The structure is subsequently analyzed as a series system of correlated elements and the Ditlevsen bounds are used for the calculation of its reliability index. The uncertain-random parameters considered in this work are the load, the yield-critical stress; and the cross sections of the elements. The considered design variables of the optimization problem are the cross-sectional areas of the groups, which control the size of the truss, and the heights and lengths that control the shape of the truss. The results of the optimization are presented for a 25-bar truss and a 30-bar arch and the robustness of the optimization scheme is discussed.     

用粒子群算法优化编制露天矿生产作业计划

从露天矿采掘和运输成本的最小化角度出发,构建露天矿生产作业计划模型.基于群体智能优化理论,提出了用粒子群算法对露天矿生产作业计划模型进行解算的方法,并在求解过程中设计了带核粒子及双吸引子的粒子搜索策略.以MATLAB软件为平台进行求解运算最佳作业计划.以某露天铁矿为工程背景进行实例研究,将研究结果与露天矿实际生产指标和非线性规划解算结果进行比较验证.结果表明,粒子群算法可用于露天矿生产作业计划的优化编制.      

Time-Cost-Quality Trade-Off Analysis for Highway Construction

Many departments of transportation have recently started to utilize innovative contracting methods that provide new incentives for improving construction quality. These emerging contracts place an increasing pressure on decision makers in the construction industry to search for an optimal resource utilization plan that minimizes construction cost and time while maximizing its quality. This paper presents a multiobjective optimization model that supports decision makers in performing this challenging task. The model is designed to transform the traditional two-dimensional time-cost tradeoff analysis to an advanced three-dimensional time-cost-quality trade-off analysis. The model is developed as a multiobjective genetic algorithm to provide the capability of quantifying and considering quality in construction optimization. An application example is analyzed to illustrate the use of the model and demonstrate its capabilities in generating and visualizing optimal tradeoffs among construction time, cost, and quality.     

基于工序加工能力的并行公差优化设计新方法

文献[1]提出了一种基于工序加工能力的并行工序公差优化设计方法,并用优化算法求解优化模型,本文提出了一种将遗传算法与复合形算法相结合而构成的遗传复合形算法。在遗传算法初始化之后,用复合形法先进行局部寻优,选出较好的个体,再用遗传算法在全局寻求最优解,将其应用于并行公差模型,与资料[1]中结果做比较,发现较以前的算法有较大改进。     

Optimal Construction Site Layout Considering Safety and Environmental Aspects

A good site layout is vital to ensure the safety of the working environment and effective and efficient operations. Site layout planning has significant impacts on productivity, costs, and duration of construction. Construction site layout planning involves identifying, sizing, and positioning temporary and permanent facilities within the boundary of the construction site. Site layout planning can be viewed as a complex optimization problem. Although construction site layout planning is a critical process, systematical analysis of this problem is always difficult because of the existence of a vast number of trades and interrelated planning constraints. The problem has been solved using two distinct approaches: Optimization techniques and heuristics methods. Mathematical optimization procedures have been developed to produce optimal solutions, but they are only applicable for small-size problems. Artificial intelligent techniques have been used practically to handle real-life problems. On the other hand, heuristic methods have been used to produce good but not optimal solutions for large problems. In this paper, an optimization model has been developed for solving the site layout planning problem considering safety and environmental issues and actual distance between facilities. Genetic algorithms are used as an optimization bed for the developed model. In order to validate the performance of the developed model, a real-life construction project was tested. The obtained results proved that satisfactory solutions were obtained.     

Optimal Design of Pressurized Irrigation Subunit

A linear programming (LP) model is presented for optimal design of the pressurized irrigation system subunit. The objective function of the LP is to minimize the equivalent annual fixed cost of pipe network of the irrigation system and its annual operating energy cost. The hydraulic characteristics in the irrigation subunit are ensured by using the length, energy conservation, and pressure head constraints. The input data are the system layout, segment-wise cost and hydraulic gradients in all the alternative pipe diameters, and energy cost per unit head of pumping water through the pipeline network. The output data are: segment-wise lengths of different diameters, operating inlet pressure head, and equivalent annual cost of the pipeline network. The explicit optimal design is demonstrated with design examples on lateral and submain or manifold of pressurized irrigation systems. The effect of the equations for friction head loss calculation on optimization procedure is investigated through the design example for microirrigation manifold. The performance evaluation of the proposed model in comparison with the analytical methods, graphical methods, numerical solutions, and dynamic programming optimization model reveals the good performance of the proposed model. The verification of operating inlet pressure head obtained by the proposed model with accurate numerical step-by-step method suggested that it is mostly accurate.     

Paleolithic and Neolithic lineages in the European mitochondrial gene pool

PURPOSE: This article presents a new optimization method for stereotactic radiosurgery treatment planning for gamma unit treatment system. METHODS AND MATERIALS: The gamma unit has been utilized in stereotactic radiosurgery for about 30 years, but the usual procedure for a physician-physicist team to design a treatment plan is a trial-and-error approach. Isodose curves are viewed on two-dimensional computed tomography (CT) or magnetic resonance (MR) image planes, which is not only time consuming but also seldom achieves the optimal treatment plan, especially when the isocenter weights are regarded. We developed a treatment-planning system on a computer workstation in which Powell's optimization method is realized. The optimization process starts with the initial parameters (the number of isocenters as well as corresponding 3D isocenters' coordinates, collimator sizes, and weight factors) roughly determined by the physician-physicist team. The objective function can be changed to consider protection of sensitive tissues. RESULTS: We use the plan parameters given by a well-trained physician-physicist team, or ones that the author give roughly as the initial parameters for the optimization procedure. Dosimetric results of optimization show a better high dose-volume conformation to the target volume compared to the doctor's plan. CONCLUSION: This method converges quickly and is not sensitive to the initial parameters. It achieves an excellent conformation of the estimated isodose curves with the contours of the target volume. If the initial parameters are varied, there will be a little difference in parameters' configuration, but the dosimetric results proved almost to be the same.     

Materials Handling System Simulation in Precast Viaduct Construction: Modeling, Analysis, and Implementation

The interactive, complicated system environment of a construction site renders conventional site layout planning and scheduling techniques to be inadequate in coping with materials handling system design in construction. In this paper, we present a university-industry joint endeavor for improving the effectiveness of the materials handling system on a precast viaduct construction project in Hong Kong by implementing the simplified discrete-event simulation approach (SDESA) along with its computer platform resulting from recent research. How to apply the simulation methodology of SDESA is elaborated step by step. Particular emphasis is placed on procedures of establishing a simulation model, validation of the simulation model, design of simulation experiments, and analysis of simulation results. With process flowchart, site layout plan, and process animation produced in a view-centric simulation environment, it is straightforward to establish, validate, and communicate the operations simulation. The research team convinced the project director, as well as field managers, of the functionality and effectiveness of operations simulation. The knowledge derived from simulation added to experiences of site managers in materials handling system design. With the aid of simulation, even junior engineers would be capable and confident to draw up an actionable construction plan that would lead to enhancement of cost effectiveness and productivity in the field.