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排序方式: 共有393条查询结果,搜索用时 46 毫秒
1.
In this paper, Parallel Evolutionary Algorithms for integer weightneural network training are presented. To this end, each processoris assigned a subpopulation of potential solutions. Thesubpopulations are independently evolved in parallel andoccasional migration is employed to allow cooperation betweenthem. The proposed algorithms are applied to train neural networksusing threshold activation functions and weight values confined toa narrow band of integers. We constrain the weights and biases inthe range [–3, 3], thus they can be represented by just 3 bits.Such neural networks are better suited for hardware implementationthan the real weight ones. These algorithms have been designedkeeping in mind that the resulting integer weights require lessbits to be stored and the digital arithmetic operations betweenthem are easier to be implemented in hardware. Another advantageof the proposed evolutionary strategies is that they are capableof continuing the training process ``on-chip', if needed. Ourintention is to present results of parallel evolutionaryalgorithms on this difficult task. Based on the application of theproposed class of methods on classical neural network problems,our experience is that these methods are effective and reliable.  相似文献   
2.
初飞雪  吴长春 《石油学报》2006,27(2):116-120
基于计算期内总费用最小现值建立了干线成品油管道工艺方案优化设计的数学模型,分析了分输方式、分输流量变化及工艺计算参数的选取等问题。考虑到传统数值算法求解多变量混合整数非线性规划问题的局部最优性及对初值敏感性强等缺陷,针对所建立的数学模型的特点,引进了一种较新的全局搜索算法——杂交差分进化方法,并对其进行了局部改进,采取了动态处理约束条件的措施。在泵站可选位置确定的条件下,采用赋权有向图来表示工艺方案优化设计问题。泵站位置候选点对应图的顶点,两顶点间管道的总费用现值对应弧的权值。通过递归调用Dijkstra算法,求解出了前N条最短路径对应的最优和次优方案,并以其作为进一步进行多因素方案比选的候选方案。用实际算例说明了上述方法的有效性。  相似文献   
3.
相控阵天线的互耦和近场校准   总被引:2,自引:1,他引:1       下载免费PDF全文
范瑜  金荣洪  耿军平  刘波 《电子学报》2004,32(12):1997-2000
 本文在分析相控阵天线近场特性的基础上,根据信号子空间的基本理论,结合模拟退火算法,提出了一种利用近场辅助源估计相控阵天线互耦系数的方法.大量的计算机仿真结果表明,本方法使用校准源少,校准源到天线阵距离近,算法稳健,即使在雷达工作、并且存在其它未知信号时,也能准确估计出天线阵的互耦系数.  相似文献   
4.
Selection of cutting parameters in high-speed machining is one of the most important tasks to achieve the required level of quality. Evolutionary algorithms are often used to obtain the optimal parameters corresponding to a single value of surface finish. In most practical applications, it is necessary to determine the cutting speed, feed, and depth of cut to meet the required surface finish. In the present work, high-speed end-milling has been studied, and an objective function for surface finish is obtained by Response Surface Methodology using results of carefully designed experiments. Testing of differential evolution and genetic algorithms using the classical Himmelblau function reveals that the performance of differential evolution is better. Therefore, differential evolution is used in the present work with a newly proposed objective function, and the machining parameters for the required surface finish are obtained.  相似文献   
5.
近年来,磁漂浮的方法测量分数电荷的实验的兴起使得Millikan油滴实验又重新站到了实验物理的前列;尽管通过繁琐的实验和运算得到了油滴电量值,但由于实验误差造成油滴电量的非整数性,使得通过寻求油滴电荷量或油滴带电量之差的最大公约数(GCD)确定基本电荷的方法难以实现。论文分析了Millikan油滴实验中几种常用的典型数据处理方法的优缺点,基于把最大公约数转化为线性模型的思想,运用差异演化算法(DE)的并行寻优优势,将DE应用于数据分析,直接寻找基本电荷的大小;数值实验验证了该方法的有效性,表明该方法克服了目前大多数方法不能反映实验真实结果的缺陷。  相似文献   
6.
针对多用户正交频分复用系统自适应资源分配问题,提出一种改进的子载波和基于差分进化算法的功率自适应分配算法.该算法首先在均等功率下进行子载波分配,然后通过添加约束条件检测改进步骤,改进差分进化算法,并采用该算法根据设置的兼顾用户公平性与系统容量的目标函数,全局寻优实现用户间的功率分配.仿真结果表明,算法在低算法复杂度及兼顾用户公平性的情况下实现了较高的系统容量提升,证明其有效性.  相似文献   
7.
An efficient, adaptive differential evolution (DE) algorithm is proposed in which DE parameter adaptation is implemented. A ranking-based vector selection and crossover rate repairing technique are also presented. The method is referred to as IJADE (Improved Jingqiao Adaptive DE). To verify the performance of IJADE, the parameters of a simple SOFC electrochemical model that is used to control the output performance of an SOFC stack are identified and optimized. The SOFC electrochemical model is built to provide the simulated data. The results indicate that the proposed method is able to efficiently identify and optimize model parameters while showing good agreement with both simulated and experimental data. Additionally, when compared to other DE variants and other evolutionary algorithms, IJADE obtained better results in terms of the quality of the final solutions, robustness, and convergence speed.  相似文献   
8.
为了更加合理地制定冷连轧轧制规程,选取打滑因子、等功率裕度和最小能耗作为目标函数,采用改进的差分进化算法求解Pareto前沿,减少了冗余的寻优代数、缩短了优化时间。以求解出的Pareto前沿为选择池,基于不同的偏好因子选择出不同的负荷分配方法,满足不同工况下的要求。仿真结果表明,该算法可以快速均匀地覆盖Pareto前沿,产生偏重于不同目标的负荷分配规则。优化规程与原规程相比,降低了打滑现象出现的概率,减小了轧制功率。  相似文献   
9.
This paper presents a variable iterated greedy algorithm (IG) with differential evolution (vIG_DE), designed to solve the no-idle permutation flowshop scheduling problem. In an IG algorithm, size d of jobs are removed from a sequence and re-inserted into all possible positions of the remaining sequences of jobs, which affects the performance of the algorithm. The basic concept behind the proposed vIG_DE algorithm is to employ differential evolution (DE) to determine two important parameters for the IG algorithm, which are the destruction size and the probability of applying the IG algorithm to an individual. While DE optimizes the destruction size and the probability on a continuous domain by using DE mutation and crossover operators, these two parameters are used to generate a trial individual by directly applying the IG algorithm to each target individual depending on the probability. Next, the trial individual is replaced with the corresponding target individual if it is better in terms of fitness. A unique multi-vector chromosome representation is presented in such a way that the first vector represents the destruction size and the probability, which is a DE vector, whereas the second vector simply consists of a job permutation assigned to each individual in the target population. Furthermore, the traditional IG and a variable IG from the literature are re-implemented as well. The proposed algorithms are applied to the no-idle permutation flowshop scheduling (NIPFS) problem with the makespan and total flowtime criteria. The performances of the proposed algorithms are tested on the Ruben Ruiz benchmark suite and compared to the best-known solutions available at http://soa.iti.es/rruiz as well as to those from a recent discrete differential evolution algorithm (HDDE) from the literature. The computational results show that all three IG variants represent state-of-art methods for the NIPFS problem.  相似文献   
10.

Purpose

The objective of this study is to optimize task scheduling and resource allocation using an improved differential evolution algorithm (IDEA) based on the proposed cost and time models on cloud computing environment.

Methods

The proposed IDEA combines the Taguchi method and a differential evolution algorithm (DEA). The DEA has a powerful global exploration capability on macro-space and uses fewer control parameters. The systematic reasoning ability of the Taguchi method is used to exploit the better individuals on micro-space to be potential offspring. Therefore, the proposed IDEA is well enhanced and balanced on exploration and exploitation. The proposed cost model includes the processing and receiving cost. In addition, the time model incorporates receiving, processing, and waiting time. The multi-objective optimization approach, which is the non-dominated sorting technique, not with normalized single-objective method, is applied to find the Pareto front of total cost and makespan.

Results

In the five-task five-resource problem, the mean coverage ratios C(IDEA, DEA) of 0.368 and C(IDEA, NSGA-II) of 0.3 are superior to the ratios C(DEA, IDEA) of 0.249 and C(NSGA-II, IDEA) of 0.288, respectively. In the ten-task ten-resource problem, the mean coverage ratios C(IDEA, DEA) of 0.506 and C(IDEA, NSGA-II) of 0.701 are superior to the ratios C(DEA, IDEA) of 0.286 and C(NSGA-II, IDEA) of 0.052, respectively. Wilcoxon matched-pairs signed-rank test confirms there is a significant difference between IDEA and the other methods. In summary, the above experimental results confirm that the IDEA outperforms both the DEA and NSGA-II in finding the better Pareto-optimal solutions.

Conclusions

In the study, the IDEA shows its effectiveness to optimize task scheduling and resource allocation compared with both the DEA and the NSGA-II. Moreover, for decision makers, the Gantt charts of task scheduling in terms of having smaller makespan, cost, and both can be selected to make their decision when conflicting objectives are present.  相似文献   
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