The optimum design of robotic manipulators using dexterity indices

This paper presents new dexterity indices that can be applied to planar and spatial manipulators. These indices are based on the condition number of the Jacobian matrix of the manipulators which is known to be a measure of their kinematic accuracy. Dexterity indices based on that same criterion have been presented elsewhere. However, due to the formulation of the kinematic equations, the existing indices are affected by a scaling of the manipulator when both the position and the orientation of the end effector are included in the kinematic equations. A new formulation of these equations is proposed here to avoid this problem of dimensional dependence. Two dexterity indices are presented for planar manipulators: the first one is based on a redundant formulation of the velocity equations whereas the second one is based on the mininum number of parameters. The corresponding indices are also derived for spatial manipulators. Finally, an example is included to illustrate the use of these indices in the context of design and optimization of manipulators.     

Vibration reduction optimum design of a steam-turbine rotor-bearing system using a hybrid genetic algorithm

This paper describes the vibration optimum design for the low-pressure steam-turbine rotor of a 1007-MW nuclear power plant by using a hybrid genetic algorithm (HGA) that combines a genetic algorithm and a local concentration search algorithm using a modified simplex method. This algorithm not only calculates the optimum solution faster and more accurately than the standard genetic algorithm but can also find the global and local optimum solutions. The objective function is to minimize the resonance response (Q-factor) of the second occurring mode in the excessive vibration. Under the constraints of shaft diameter, bearing length and clearance, these factors play a very important role in the design of a rotor-bearing system. In the present work, the shaft diameter, bearing length and clearance are chosen as the design variables. The results show that the HGA can reduce the excessive response at the critical speed and improve the stability.     

Fire accident reconstruction based on LES field model by using orthogonal experimental design method

The main objective of fire accident reconstruction is to determine the fire source and find out the fire spread. The temperature and the fire spread mark are the most important information in a fire accident, the information can be fully utilized based on Large Eddy Simulation (LES) field model, which has been widely used as simulation model for fire analyses. However, this model is not popular in fire accident reconstruction because it needs lots of simulation runs, which increases the reconstruction time and cost. The use of orthogonal experimental design (OED) method as a tool to reduce the simulation runs in fire accident reconstruction is proposed in this research. An orthogonal array is selected on a discrete design space and levels are chosen from candidate values. Matrix experiments with the orthogonal array are conducted and range difference analysis is used to find out the optimum levels. The method proposed in this research is applied to a typical house fire accident as a validation. A group of optimum levels was obtained and the corresponding simulation was studied. The reconstruction results can provide a scientific foundation for accident judgements.     

Extension of optimum safety factor method to nonlinear reliability-based design optimization

In the reliability-based design optimization (RBDO) model, the mean values of uncertain system variables are usually applied as design variables, and the cost is optimized subject to prescribed probabilistic constraints as defined by a nonlinear mathematical programming problem. Therefore, a RBDO solution that reduces the structural weight in uncritical regions does not only provide an improved design but also a higher level of confidence in the design. In this paper, we present recent developments for the RBDO model relative to two points of view: reliability and optimization. Next, we develop several distributions for the hybrid method and the optimum safety factor methods (linear and nonlinear RBDO). Finally, we demonstrate the efficiency of our safety factor approach extended to nonlinear RBDO with application to a tri-material structure.     

An integrated model and a decomposition-based approach for concurrent layout and material handling system design

This paper presents an integer programming formulation that integrates decisions concerning the layout of the resource groups on the shop floor with the design of the material handling system. The model reflects critical practical concerns, including the capacity of the material flow network and of the handling transporters, as well as the tradeoff between fixed (construction and acquisition) and variable (operational) costs. For realistic industrial cases, the size of the problem prevents the solution using explicit or implicit enumeration methods. Instead, the global model is decomposed into standard optimization problems: quadratic assignment, fixed charge capacitated network design, and non-depot distance-constrained vehicle routing. An integrated solution method, guided by a simulated annealing scheme, solves the global shop design problem. The algorithm takes advantage of the proposed decomposition and converges to a final design which is feasible with respect to all problem constraints. The method is applied to redesign the facility of a large manufacturer of radar antennas. The resulting shop configuration exhibits substantially decreased material handling effort, and requires significantly smaller investment costs compared to the existing facility.     

Exception handling refactorings: Directed by goals and driven by bug fixing

Exception handling design can improve robustness, which is an important quality attribute of software. However, exception handling design remains one of the less understood and considered parts in software development. In addition, like most software design problems, even if developers are requested to design with exception handling beforehand, it is very difficult to get the right design at the first shot. Therefore, improving exception handling design after software is constructed is necessary. This paper applies refactoring to incrementally improve exception handling design. We first establish four exception handling goals to stage the refactoring actions. Next, we introduce exception handling smells that hinder the achievement of the goals and propose exception handling refactorings to eliminate the smells. We suggest exception handling refactoring is best driven by bug fixing because it provides measurable quality improvement results that explicitly reveal the benefits of refactoring. We conduct a case study with the proposed refactorings on a real world banking application and provide a cost-effectiveness analysis. The result shows that our approach can effectively improve exception handling design, enhance software robustness, and save maintenance cost. Our approach simplifies the process of applying big exception handling refactoring by dividing the process into clearly defined intermediate milestones that are easily exercised and verified. The approach can be applied in general software development and in legacy system maintenance.     

Optimum design of steel frames using harmony search algorithm

In this article, harmony search algorithm was developed for optimum design of steel frames. Harmony search is a meta-heuristic search method that has been developed recently. It bases on the analogy between the performance process of natural music and searching for solutions to optimization problems. The objective of the design algorithm is to obtain minimum weight frames by selecting suitable sections from a standard set of steel sections such as American Institute of Steel Construction (AISC) wide-flange (W) shapes. Strength constraints of AISC load and resistance factor design specification and displacement constraints were imposed on frames. The effectiveness and robustness of harmony search algorithm, in comparison with genetic algorithm and ant colony optimization-based methods, were verified using three steel frames. The comparisons showed that the harmony search algorithm yielded lighter designs.     

OPTSHIP: a new optimization framework and its application to optimum design of ship structure

This paper proposes an optimization framework called OPTSHIP (OPTimization for SHIP) by integrating NASTRAN external analyzer with some global optimization algorithms to enhance optimum design for vibration reduction of ship structure. The merits of this framework are used for global searching and selection of various objective functions and design variables. It is especially relatively easy to apply for optimum design of a big and complex structure such as a merchant ship. The global optimization algorithms used here are random tabu search method and genetic algorithm. Moreover, an example of optimum design to reduce the vibration level of a deckhouse according to the strict vibration criteria is presented to verify the performance of the proposed algorithm. The results show that the reduction of vibration velocity reaches 33.5%, which indicates that the proposed method is relatively effective and can be applied in real-world optimization.     

基于汽车操纵动力学的神经网络驾驶员模型

作为人一车—路闭环系统的重要环节,驾驶员模型对汽车闭环系统仿真和汽车主动安全性评价都具有重要的意义.本文基于汽车操纵动力学,预瞄—跟随理论以及神经网络建立了一种驾驶员方向控制模型,即两层前馈神经网络驾驶员模型,并在此基础上建立了驾驶员—汽车闭环系统模型.对该闭环模型进行了单移线与双移线仿真试验,仿真结果与理想数据具有很好的一致性,表明该驾驶员模型是合理的,可以有效地模拟驾驶员控制汽车方向的行为特性,为进一步研究人一车一路闭环系统提供了一条可行途径.     

Colliding Bodies Optimization method for optimum design of truss structures with continuous variables

In recent years, the importance of economical considerations in the field of structures has motivated many researchers to propose new methods for minimizing the weight of the structures. In this paper, a new and simple optimization algorithm is presented to solve weight optimization of truss structures with continuous variables. The Colliding Bodies Optimization (CBO) is an algorithm based on one-dimensional collisions between two bodies, where each agent solution is modeled as the body. After a collision of two moving bodies, having specified masses and velocities, these are separated and moved to new positions with new velocities. This process is repeated until a termination criterion is satisfied and the optimum CB is found. Comparison of the results of the CBO with those of some previous studies, demonstrate its capability in solving the present optimization problems.     

间歇精馏常规设计和优化设计的模型及算法

建立了板式间歇精馏塔在恒馏出液组成操作状况下常规设计及优化设计的数学模型。常规设计模型用数值方法编程求解,对二元理想及非理想溶液均适用。优化设计模型以间歇精馏系统年效益最大为优化目标,用菲波那契法求解单变量优化问题,用复合形法求解多变量优化问题。模型同时考虑对整个间歇精馏系统(包括塔主体、塔顶冷凝器及塔底再沸器)进行优化,更符合工程实际情况。求解模型可得到间歇精馏过程最优的一系列设计和操作参数(如理论板数,塔径,操作回流比,塔釜蒸发量,釜残液组成,冷凝器传热面积及冷却水出口温度,再沸器传热面积及加热蒸汽温度等)。算例表明,对恒馏出液组成间歇精馏单变量及多变量优化设计比常规设计分别提高年效益2．6％和18．9％。     

Harmony search based algorithm for the optimum design of grillage systems to LRFD-AISC

Harmony search based optimum design method is presented for the grillage systems. This numerical technique imitates the musical performance process that takes place when a musician searches for a better state of harmony. Jazz improvisation seeks to find musically pleasing harmony similar to the optimum design process which seeks to find the optimum solution. The design algorithm considers the serviceability and ultimate strength constraints which are implemented from Load and Resistance Factor Design—American Institute of Steel Construction (LRFD-AISC). It selects the appropriate W-sections for the transverse and longitudinal beams of the grillage system out of 272 discrete W-section designations given in LRFD-AISC. This selection is carried out such that the design limitations described in LRFD-AISC are satisfied and the weight of the system is the minimum. Many design examples are considered to demonstrate the efficiency of the algorithm presented.     

均匀设计法优化固体酒精的制备工艺

利用均匀设计和二次回归分析的方法对固体酒精的制备工艺进行了研究。得到固体酒精的较为理想的工艺条件为:辅助原料4份、硬脂酸4份、乙醇55份和乌洛托品5份。结果表明,通过该工艺合成的固体酒精具有较低的残渣率、较长的燃烧时间和较高的有效燃烧热,与理论计算结果基本相符。     

基于简化模型的T型微反应器设计

分析T型微反应器内流体混合程度和反应产物收率的常用方法:是建立计算流体动态模型,也就是CFD模型,可是这种模型不适用于微反应器的优化设计,因为利用CFD模型进行优化计算需要的大量的计算时间。本研究开发了一个描述T型微反应器流体流动状态的简化模型,通过假设边界条件和假设扩散系数的设定来计算微反应器内反应产物收率。其中假设边界条件用来描述强混合效果在反应通道入口处的流动状态,假设扩散系数用来描述混合效果在流动路径上的变化。本研究依据此简化模型,确立了一种优化设计方法:,用来设计具有最优尺寸的T型微反应器。优化问题的目标函数是最大反应产物收率,优化约束包括反应通道尺寸约束和操作压力约束。在求解过程中,首先建立尺寸约束边界条件下的CFD模型,然后依据CFD模型计算结果:,求解简化模型中的未知参数。将建好的简化模型作为优化问题的等式约束,最后求出最优的T型微反应器。简化模型和优化设计方法:的有效性通过一个快速平行串联反应在微反应器中的反应过程来验证。简化模型的优化设计结果:和CFD模型验证结果:高度一致。     

Conceptual design of object-oriented database schemas using the binary-relationship model

We describe an algorithmic method for transforming a binary-relationship (BR) conceptual schema to an object-oriented (OO) database schema. The BR schema is a semantically rich diagram that represents the reality being modeled in terms of objects, relationships and constraints. It is easy to understand and serves as a communication tool between users and designers. Therefore it can be created in the early stages of system development, and later on be transformed into a specific OO database schema. The transformation method employs a multi-stage algorithm, which first identifies the essential objects in the BR schema, together with their relationships and constraints. These are then mapped to object classes, attributes, and constraints, maintaining the semantics and all types of constraints present in the conceptual schema.     

An evaluation of classification algorithms for manual material handling tasks based on data obtained using wearable technologies

With recent progress in wearable measurement systems, physical exposures can be feasibly assessed at high precision in the workplace. Such systems, however, generally lack contextual information for a given job (e.g. task type, duration). To extract such information, we explored three classification algorithms to classify manual material handling (MMH) tasks during a simulated job in a laboratory, using several combinations of outputs from commercially available inertial motion capture and in-shoe pressure measurement systems. A total of 10 participants completed three replications of four cycles of a simulated job. Precision and recall values of ≥ ～90% and 80%, respectively, and errors in estimated task duration of < ～14%, could be achieved across the MMH task examined. Classification performance, however, varied between classification algorithms, input data sets and task types. Overall, combining wearable technology with task classification could be an effective approach for field-based exposure assessment, though field-testing is needed to demonstrate the applicability of this method.

Practitioner Summary: Combining wearable technologies with task classification was explored to extract exposure context, specifically task type and duration. Results supported that task classification can facilitate the use of wearable technologies in field-based exposure assessment, specifically by aiding in task identification from within the rather large data sets obtained from these technologies.     

A comprehensive data base for the design of manual materials handling

The main objective of the present paper is to provide a comprehensive data base of the material handling capabilities of the industrial work force. The data base encompasses the following: (1) five different types of manual materials handling activities, namely, lifting, lowering, carrying, pushing, and pulling, (2) worker variables (e.g., sex), and (3) task variables (e.g., frequency, and container size). The data base was developed for the IBM personal computer using the software package DBASE III PLUS.     

基于偏最小二乘法的翼型稳健设计替代模型

翼型的稳健设计就是要实现翼型对外界噪声因素不敏感,使翼型实现性能高且稳定的目标。翼型设计经过了几十年的研究发展,目前常用的翼型稳健设计主要是采用风洞和数值模拟两种方式,但它们也分别有成本高和计算量大的不足。通过对建模方法进行研究,提出了一种基于偏最小二乘法（PLS)的翼型稳健设计方法,采用该方法对基准翼型RAE2822选取11个设计变量（10个外形设计变量和马赫数）进行稳健设计后将其与基准翼型的阻力系数进行对比。结果表明使用偏最小二乘法替代模型所获得的稳健翼型,其阻力系数的均值和方差较基准翼型分别减小了44%和82%,其气动性能更好且性能更加稳定。使用偏最小二乘法替代模型进行翼型稳健设计具有成本低,计算速度快的特点,且能满足基本的结果精度要求,具有实际的应用价值。     

Reliability-based optimum design of cable-stayed bridges

This paper presents a procedure for finding the reliability-based optimum design of cable-stayed bridges. The minimisation problem is stated as the minimisation of stresses, displacements, reliability and bridge cost. A finite-element approach is used for structural analysis. It includes a direct analytic sensitivity analysis module, which provides the structural behaviour responses to changes in the design variables. An equivalent multicriteria approach is used to solve the non-differentiable, non-linear optimisation problem, turning the original problem into the sequential minimisation of unconstrained convex scalar functions, from which a Pareto optimum is obtained. Examples are given illustrating the procedure.