稀疏矢量阵设计的模拟退火算法

对于均匀间隔线列阵,由采样定理可知,当阵元间距超过信号波长的一半时,指向性图会产生与目标等高的栅瓣。为了获得高分辨率,同时避免栅瓣出现,需要大量的传感器。为了减少设备复杂度,可以采用稀疏布阵技术,以较少的阵元获得较高的分辨力。将模拟退火算法应用到稀疏矢量水听器阵的设计中。通过优化阵元位置控制指向性图,可以获得无栅瓣的指向性图。给出了优化后的稀疏矢量阵与均匀间隔矢量阵的指向性图比较。     

遥控起爆器的汉明码纠错应用研究

(8,4)汉明码易于遥控起爆器实现纠错功能,文章给出了其编译码算法,并采用CC1100无线模块对其性能进行了测试。测试结果表明,采用(8,4)汉明码,误码率最大降低了80%,遥控距离最大增加了近50%。(8,4)汉明码能有效降低遥控起爆的误码率,增加遥控距离,在遥控起爆器中具有很强的实用价值。     

Acoustic behavior design with simulated annealing

The present work extends the matrix method formalism, by using a supplementary computational method based on a simulated annealing algorithm, with the aim to design acoustical structures, especially acoustic filters. The algorithm introduces a cost function, which is minimized by the simulated annealing algorithm. Also, some numerical computations have been carried out to design some special acoustic filters and an experimental analysis of the designed acoustic filters is provided to test the validity of the method.     

提高彩色PDP显示灰度等级的准延伸编码方法

为了解决延伸编码在消除动态假轮廓时存在显示灰度等级不够和需要子场数目多的不足 ,从动态假轮廓的成因入手 ,吸取延伸编码和常规编码的长处 ,提出了准延伸编码方法 ,该方法能够使用较少的子场数目来提高PDP的显示灰度等级 ,同时有效地消除了动态假轮廓现象。仿真结果表明 ,采用准延伸编码方法 ,运动图像和静止图像的相关系数为 0 8972 ,使图像显示质量大为改善     

A global single-loop deterministic approach for reliability-based design optimization of truss structures with continuous and discrete design variables

A single-loop deterministic method (SLDM) has previously been proposed for solving reliability-based design optimization (RBDO) problems. In SLDM, probabilistic constraints are converted to approximate deterministic constraints. Consequently, RBDO problems can be transformed into approximate deterministic optimization problems, and hence the computational cost of solving such problems is reduced significantly. However, SLDM is limited to continuous design variables, and the obtained solutions are often trapped into local extrema. To overcome these two disadvantages, a global single-loop deterministic approach is developed in this article, and then it is applied to solve the RBDO problems of truss structures with both continuous and discrete design variables. The proposed approach is a combination of SLDM and improved differential evolution (IDE). The IDE algorithm is an improved version of the original differential evolution (DE) algorithm with two improvements: a roulette wheel selection with stochastic acceptance and an elitist selection technique. These improvements are applied to the mutation and selection phases of DE to enhance its convergence rate and accuracy. To demonstrate the reliability, efficiency and applicability of the proposed method, three numerical examples are executed, and the obtained results are compared with those available in the literature.     

Controlling asynchronous team design environments by simulated annealing

An organizational strategy for design environments,asynchronous teams, is reviewed. Simulated annealing is used to implement the necessarycontracting search behavior of asynchronous teams. An example of an asynchronous team design environment controlled by simulated annealing is given from the building design domain. The simulated annealing algorithm used, which has been modified for distributed use and multi-criteria, non-preference objectives, is described.     

Recursive annealing: A computational model for machine design

We propose a model for optimally directed conceptual design of machines in which the transformation of function to form occurs iteratively along an abstraction continuum. An algorithm called FFREADA is introduced as a computational implementation of the model. FFREADA is a grammar-based optimizing design algorithm that uses recursive simulated annealing to generate optimally directed designs. During FFREADA's design process, the mapping of function to form is accomplished using an abstraction grammar production system and a predefined library of function and form entities. FFREADA also has a random design generation mode that can be used to record data to characterize the space of design solutions. FFREADA is demonstrated by designing an idealized power supply using a variety of performance objectives. Results show the algorithm able to explore and record information about a tractably infinite design space before converging to the optimal design.     

Two new decoding algorithms for Reed-Solomon codes

The subject of decoding Reed-Solomon codes is considered. By reformulating the Berlekamp and Welch key equation and introducing new versions of this key equation, two new decoding algorithms for Reed-Solomon codes will be presented. The two new decoding algorithms are significant for three reasons. Firstly the new equations and algorithms represent a novel approach to the extensively researched problem of decoding Reed-Solomon codes. Secondly the algorithms have algorithmic and implementation complexity comparable to existing decoding algorithms, and as such present a viable solution for decoding Reed-Solomon codes. Thirdly the new ideas presented suggest a direction for future research. The first algorithm uses the extended Euclidean algorithm and is very efficient for a systolic VLSI implementation. The second decoding algorithm presented is similar in nature to the original decoding algorithm of Peterson except that the syndromes do not need to be computed and the remainders are used directly. It has a regular structure and will be efficient for implementation only for correcting a small number of errors. A systolic design for computing the Lagrange interpolation of a polynomial, which is needed for the first decoding algorithm, is also presented.This research was supported by a grant from the Canadian Institute for Telecommunications Research under the NCE program of the Government of Canada     

Simulated annealing applied to the optimal plastic design of circular steel plates

This article describes an application of the simulated annealing (SA) algorithm to a structural problem, consisting in finding a minimum‐weight circular plate of the imposed limit load. For technological reasons, the considered plates are divided into rings of constant thickness. The boundaries of these rings may vary, so the thickness and size of each ring are the design variables to be considered. Although SA is mostly applied to handle combinatorial optimization problems, the present study shows that it can also be efficient in the field of mechanical engineering. Some particular aspects of the study are thoroughly described. For instance, technological constraints have to be considered: lower and upper bounds are imposed on the thickness of each ring, and a lower bound is imposed on the ring width. These constraints are not taken into account by means of a classical penalty method, but by a set of dedicated procedures. The particular constraint of the imposed limit load is treated by solving the inverse problem at each iteration: the limit load of the current solution is computed and the geometry of the plate is adapted to fit the assigned value. After discussion about points of attention, general conclusions are drawn from the performances of SA in its present implementation. The obtained results show that the algorithm exhibits satisfactory levels of reliability and efficiency. Copyright © 2007 John Wiley & Sons, Ltd.     

A two-stage simulated annealing procedure for block layout problems

Rules for setting simulated annealing control parameters are proposed for block layout problems where different material-handling devices are dynamically assigned to individual material movements as layout solutions are perturbed. Recognizing the high cost of computing materials-handling cost in this type of problem, the rules are based on adapting an existing two-stage simulated annealing procedure to accelerate convergence. Experimental results suggest that the application of these rules yields solution quality comparable with other single and two-stage simulated annealing algorithms but with significantly fewer re-evaluations of the objective function.     

A simulated annealing method for design of laminates with required stiffness properties

Designing a laminate based on its stiffness properties requires finding the optimum lamination stacking sequence to yield the required stiffness properties. The design variables to be considered are the number of layers and orientation angle of fibers in each layer group, which are treated as discrete-variables. The optimum lamination is then obtained by minimizing a cost function composed of the relative difference between the calculated effective stiffness properties and weight of trial laminate and the desired properties. This error minimization problem was solved using a modified simulated annealing heuristic method. The new simulated annealing implementation comprises a cooling procedure in which the temperature decrease relied adaptively on the objective function evolution. It is shown that the proposed method can give rise to an improvement in convergence speed. To achieve a further improvement in the performance of the method, simulated annealing parallelization implemented using the proposed cooling process. The main features of this algorithm are described and its encouraging results are presented.     

Fabrication of ZnO thin film diode using laser annealing

A p-n homojunction was obtained by Nd:YAG laser annealing of Zn₃P₂/n-ZnO thin film. The deposition process of ZnO and Zn₃P₂ thin film was performed by pulsed laser deposition (PLD). A p-n junction was formed by Nd:YAG laser annealing of Zn₃P₂/n-ZnO thin film and showed typical I-V characteristics of a diode. Laser annealing could be a useful technique for the fabrication of an ultraviolet light-emitting diode or an ultraviolet laser diode.     

Single and multiobjective structural optimization in discrete-continuous variables using simulated annealing

A multivariable optimization technique based on the Monte-Carlo method used in statistical mechanics studies of condensed systems is adapted for solving single and multiobjective structural optimization problems. This procedure, known as simulated annealing, draws an analogy between energy minimization in physical systems and objective function minimization in structural systems. The search for a minimum is simulated by a relaxation of the statistical mechanical system where a probabilistic acceptance criterion is used to accept or reject candidate designs. To model the multiple objective functions in the problem formulation, a cooperative game theoretic approach is used. Numerical results obtained using three different annealing strategies for the single and multiobjective design of structures with discrete-continuous variables are presented. The influence of cooling schedule parameters on the optimum solutions obtained is discussed. Simulation results indicate that, in several instances, the optimum solutions obtained using simulated annealing outperform the optimum solutions obtained using some gradient-based and discrete optimization techniques. The results also indicate that simulated annealing has substantial potential for additional applications in optimization, especially for problems with mixed discrete-continuous variables.     

Applying tabu search and simulated annealing to the optimal design of sewer networks

Optimizations of sewer network designs create complicated and highly nonlinear problems wherein conventional optimization techniques often get easily bogged down in local optima and cannot successfully address such problems. In the past decades, heuristic algorithms possessing robust and efficient global search capabilities have helped to solve continuous and discrete optimization problems and have demonstrated considerable promise. This study applied tabu search (TS) and simulated annealing (SA) to the optimization of sewer network designs. For a case study, this article used the sewer network design of a central Taiwan township, which contains significantly varied elevations, and the optimal designs from TS and SA were compared with the original official design. The results show that, in contrast with the original design's failure to satisfy the minimum flow-velocity requirements, both TS and SA achieved least-cost solutions that also fulfilled all the constraints of the design criteria. According to the average performance of 200 trials, SA outperformed TS in both robustness and efficiency for solving sewer network optimization problems.     

Laser annealing of silicon

In recent years laser processing has attracted much attention in view of its potential use in basic solid-state and material science research as well as in new processing technologies. The dominant feature of laser processing being the deposition of large amounts of energy (a few J/cm²) over very short time scales (a few tens of nanoseconds), it leads to melting of surface layers of solid followed by rapid resolidification. In this article, a few basic consequences of such laser-induced phenomena in silicon are reviewed.     

一种基于硬件的快速确定性重放方法

针对多核处理器上并行程序执行不确定性所造成的并行调试难问题,提出了一种基于硬件的快速确定性重放方法——时间切割者。该方法采用面向并行的记录机制来区分出原执行中并行执行的访存指令块和非并行执行的指令块,并在重放执行中避免串行执行那些在原执行中并行执行的访存指令块,从而使得重放执行的性能开销小。在多核模拟器Sim-Godson上的仿真实验结果表明:该方法的重放速度快,其性能开销仅为2%左右。此外,该方法还具有硬件支持简单特点,未来有望应用于国产多核处理器研制中。     

Theoretical and numerical results of a deterministic two-dimensional vortex method

The first part of the paper reviews results obtained in earlier work: (1) The outline of the derivation of an integral equation of Fredholm type with respect to vorticity from the Navier-Stokes equations, and (2) the analytical results for two deterministic vortex methods which are based on the corespreading model. The aim of the second part is to confirm the results of the previous analysis and to estimate the accuracy of these methods numerically. In the present paper, the model problem of a transient flow past an impulsively started circular cylinder is studied by several numerical methods. The numerical results show that (1) the Gaussian core-spreading methods are comparable with the random walk vortex method, (2) the numerical fluctuation of the deterministic methods is small, and (3) the number of panels is smaller than those in the random walk vortex method to obtain the flow with almost the same accuracy. The theoretical results in § 2–4 of the present paper are summarized from “Core-spreading vortex methods in two-dimensional viscous flows”,Computer methods in applied mechanics and engineering (in press), by Kida and Nakajima, with permission from Elsevier Science, The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK. The experimental picture is transferred from “The early stage of development of the wake behind an impulsively started cylinder for 40<Re<⁴”, by R Bouard and M Coutanceau,J. Fluid Mech. (1980) 101: 583–607.     

铁电薄膜退火方法的研究

以锆钛酸铅薄膜（PZT）为例，分析了国内外铁电薄膜退火的各种方法。针对解决铁电薄膜基底高温生长工艺与硅集成电路承受温度较低的不兼容及器件性质劣化的难题，分别对普通炉子退火、快速热退火及激光退火进行了详细的分析比较。激光低温退火技术有望成功地在未来应用PZT铁电薄膜制作组件时，增加其制备工艺设计的弹性和可行性。     

基于DCT域的数字盲水印技术

提出一种鲁棒性较好的DCT域数字盲水印方案。该方案将汉明编码应用于二值水印图像,同时,采用混沌调制序列伪随机选取嵌入区域,提高水印算法的安全性。通过分析DCT中频特定系数关系,实现水印的盲提取。实验结果表明,该算法对于常见的图像攻击具有较好的鲁棒性,是一种有效的盲水印。     

Metric-driven mesh optimization using a local simulated annealing algorithm

We report on results obtained with a metric-driven mesh optimization procedure for simplicial meshes based on the simulated annealing (SA) method. The use of SA improves the chances of removing pathological clusters of bad elements, that have the tendency to lock into frozen configurations in difficult regions of the model such as corners and complex face intersections, prejudicing the overall quality of the final grid. A local version of the algorithm is developed that significantly lowers the computational cost. Numerical examples illustrate the effectiveness of the proposed methodology, which is compared to a classical greedy Gauss–Seidel optimization. Substantial improvement in the quality of the worst elements of the grid is observed for the local simulated annealing optimization. Furthermore, the method appears to be robust to the choice of the algorithmic parameters. Copyright © 2006 John Wiley & Sons, Ltd.