A direct search method for determination of DAEM kinetic parameters from nonisothermal TGA data (note)

In this study, a simple direct search method to be used for the determination of distributed activation energy model (DAEM) kinetic parameters from the nonisothermal thermogravimetric analysis (TGA) data of coals has been introduced. Process steps of direct search method that depends on the grid technique have been given. The method has been applied to the nonisothermal TGA data of one Turkish coal and one imported coal, and DAEM kinetic parameters of these coal samples have been determined. Calculated model results from determined kinetic parameters have been compared with nonisothermal TGA data of the coals.     

一类新的共轭梯度法

本文提出了一类新的共轭梯度法，在算法的迭代过程中，迭代方向保持下降性，并在一类非精确性搜索条件下证明了其全局收敛性。     

曲线搜索的有关理论与数值方法

统一表达了无约束优化问题下降曲线的常微分方程组．证明了两个常见的方程组实质上是参数不同的同一曲线．指出并证明了一种方程组是有利于数值计算的．本文还提出了两个算法一基于积分的搜索法和附加插值法．研究表明曲线寻优与累积迭代信息的策略可以提高优化算法的效率和稳定性．借助于对偶规划本方法对约束优化问题也获得了效率．     

A graph partitioning heuristic for the parallel pseudo-exhaustive logical test of VLSI combinational circuits

The logical test of integrated VLSI circuits is one of the main phases of their design and fabrication. The pseudo-exhaustive approach for the logical test of integrated circults consists in partitioning the original circuits to be tested into non-overlapping subcircuits with a small, bounded number of subcircuits, which are then exhaustively tested in parallel. In this work, we present an approximate algorithm for the problem of partitioning integrated combinational circuits, based on the tabu search metaheuristic. The proposed algorithm presents several original features, such as: the use of a reduced neighborhood, obtained from moves involving only a subset of boundary nodes; complex moves which entail several resulting moves, although the variations in the cost function are easily computable; a bi-criteria cost function combining the number of subcircuits and the number of cuts, which simultaneously adds a diversification strategy to the search; and the use of a bin-packing heuristic as a post-optimization step. The behavior of the proposed algorithm was evaluated through its application to a set of benchmark circuits. The computational results have been compared with those obtained by the other algorithms in the literature, with significant improvements. The average reduction rates have been of the order of 30% in the number of subcircuits in the partition, and of the order of 40% in the number of cuts.     

On the Hardness of the Quadratic Assignment Problem with Metaheuristics

Meta-heuristics are a powerful way to approximately solve hard combinatorial optimization problems. However, for a problem, the quality of results can vary considerably from one instance to another. Understanding such a behaviour is important from a theoretical point of view, but also has practical applications such as for the generation of instances during the evaluation stage of a heuristic.In this paper we propose a new complexity measure for the Quadratic Assignment Problem in the context of metaheuristics based on local search, e.g. simulated annealing. We show how the ruggedness coefficient previously introduced by the authors, in conjunction with the well known concept of dominance, provides important features of the search space explored during a local search algorithm, and gives a rather precise idea of the complexity of an instance for these heuristics. We comment previous experimental studies concerning tabu search methods and genetic algorithms with local search in the light of our complexity measure. New computational results with simulated annealing and taboo search are presented.     

氧碘化学激光高反射薄膜的性能研究

通过实际测量和理论计算,给出高反射薄膜的散射和吸收数据,分析两种损耗对薄膜性能起的不同作用;同时,还讨论了热处理对薄膜吸收的影响.     

A Tabu Search Approach for the Resource Constrained Project Scheduling Problem

An appropriate tabu search implementation is designed to solve the resource constrained project scheduling problem. This approach uses well defined move strategies and a structured neighbourhood, defines appropriate tabu status and tenure and takes account of objective function approximation to speed up the search process. A sound understanding of the problem has helped in many ways in designing and enhancing the tabu search methodology. The method uses diversification, intensification and handles infeasibility via strategic oscillation.The above methodology is tested on existing problems from the literature and also on parametrically generated problems with encouraging results. For comparison of results, optimal solutions are used in the former and lower bounds obtained by Lagrangian heuristics are used in the latter.     

A Constraint Satisfaction Approach to a Circuit Design Problem

A classical circuit-design problem from Ebers and Moll (1954) features a system of nine nonlinear equations in nine variables that is very challenging both for local and global methods. This system was solved globally using an interval method by Ratschek and Rokne (1993) in the box [0, 10]⁹. Their algorithm had enormous costs (i.e., over 14 months using a network of 30 Sun Sparc-1 workstations) but they state that ‘at this time, we know no other method which has been applied to this circuit design problem and which has led to the same guaranteed result of locating exactly one solution in this huge domain, completed with a reliable error estimate’. The present paper gives a novel branch-and-prune algorithm that obtains a unique safe box for the above system within reasonable computation times. The algorithm combines traditional interval techniques with an adaptation of discrete constraint-satisfaction techniques to continuous problems. Of particular interest is the simplicity of the approach. This revised version was published online in July 2006 with corrections to the Cover Date.     

一种多源试验条件下惯导误差系数融合的新方法

为充分利用各种系统级试验信息提高惯导系统误差模型准确性,提出一种多源试验条件下惯导误差系数融合的新方法.根据各试验中误差系数对总误差的贡献比重来确定误差模型中可分离的误差系数.然后将各试验中分离出的误差系数分为独立系数和公共系数分别进行融合.其中,独立系数作为信任值保留,公共系数的加权融合采用以估计方差阵的迹作为代价函数的随机搜索算法来确定其融合权重.利用某型惯导系统车载、机载和火箭橇试验信息进行融合的结果表明,该方法效果较好,可行性强.     

Isomerization of stilbene using enforced geometry optimization

Using our recently proposed quantum chemical model to simulate the effect of external forces acting on a molecule (Wolinski and Baker, Mol Phys 2009, 107, 2403), which we subsequently termed enforced geometry optimization (EGO), we investigate structural isomerism in C₁₄H₁₂, starting from cis‐stilbene. By applying an external force to pairs of carbon atoms, one from each “half” of the molecule, we have generated 10 different structural isomers. Each was characterized as a minimum by vibrational analysis. Not only can EGO generate potentially new, metastable isomers it can also provide good initial guesses for transition states connecting the starting and final structures, thus giving an estimate of the stability of the new isomers to rearrangement back to the starting material. In addition to the new isomers, we provide a full set of vibrational fundamentals for cis‐ and trans‐stilbene and 4a,4b‐dihydrophenanthrene. The agreement with experimental assignments is excellent, with mean average deviations for the stilbenes of 5.0 cm^?1 or less. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010