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1.
This paper presents an efficient method for globally optimizing and automating component sizing for rotary traveling wave oscillator arrays. The lumped equivalent model of transmission lines loaded by inverter pairs is evaluated and posynomial functions for oscillation frequency, power dissipation, phase noise, etc. are formulated using transmission line theory. The re- sulting design problem can be posed as a geometric programJning problem, which can be efficiently solved with a convex opti- mization solver. The proposed method can compute the global optima more efficiently than the traditional iterative scheme and various design problems can be solved with the same circuit model. The globally optimal trade-off curves between competing objectives are also computed to carry out robust designs and quickly explore the design space. 相似文献
2.
1 Introduction Owing to the increasing demand for high reliabilityin manyindustrial processes , much attention has beenpaid to the problem of fault detection and diagnosis(FDD) in dynamic systems over the past two decades .Fruitful results can be found in a survey paper[1]andbooks[2 ,3]. It is well known that faults in a dynamic systemcantake many forms .They can be actuator faults ,sensorfaults ,unexpected abrupt changes of some parametersor even unexpected structure changes[4 ,5]. The pur-… 相似文献
3.
Analytical solution for functionally graded anisotropic cantilever beam under thermal and uniformly distributed load 总被引：1，自引：0，他引：1
HUANG De-jin DING Hao-jiang CHEN Wei-qiu 《浙江大学学报(A卷英文版)》2007,8(9):1351-1355
The bending problem of a functionally graded anisotropic cantilever beam subjected to thermal and uniformly dis-tributed load is investigated,with material parameters being arbitrary functions of the thickness coordinate. The heat conduction problem is treated as a 1D problem through the thickness. Based on the elementary formulations for plane stress problem,the stress function is assumed to be in the form of polynomial of the longitudinal coordinate variable,from which the stresses can be derived. The stress function is then determined completely with the compatibility equation and boundary conditions. A practical example is presented to show the application of the method. 相似文献
4.
Jian Zhang Jing Zhao Wen-jie Jiang Xi-wei Shan Xiao-mei Yang Jian-gang Gao 《Journal of Zhejiang University. Science. B》2012,13(7):511-524
To solve the problem of embryonic lethality in conventional gene knockouts,site-specific recombinase(SSR)systems(Cre-loxP,Flp-FRT,andΦC31)have been used for tissue-specific gene knockout.With the combination of an SSR system and inducible gene expression systems(tetracycline and tamoxifen),stage-specific knockout and transgenic expression can be achieved.The application of this"SSR+inducible"conditional tool to genomic manipulation can be extended in various ways.Alternatives to conditional gene targeting,such as conditional gene trapping,multipurpose conditional alleles,and conditional gene silencing,have been developed.SSR systems can also be used to construct precise disease models with point mutations and chromosomal abnormalities.With these exciting achievements,we are moving towards a new era in which the whole genome can be manipulated as we wish. 相似文献
5.
Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper,we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks. 相似文献
6.
Solution to impedance distribution in electrical impedance tomography （EIT） is an ill-posed nonlinear inverse problem. It is especially difficult to reconstruct an EIT image in the center area of a measured object. Tikhonov regularization with some prior information is a sound regnlarization method for static electrical impedance tomography under the condition that some true impedance distribution information is known a priori. This paper presents a direct search method （DSM） as pretreatment of image reconstruction through which one not only can construct a regularization matrix which may locate in areas of impedance change, but also can obtain an initial impedance distribution more similar to the true impedance distribution, as well as better current modes which can better distinguish the initial distribution and the true distribution. Simulation results indicate that, by using DSM, resolution in the center area of the measured object can be improved significantly. 相似文献
7.
Role-play is recommended as a useful method to solve the problem of oral English teaching. It ’s much more than a performance and it can be considered as a way to vary the kinds of spoken interaction t... 相似文献
8.
杨正瓴 《天津大学学报(英文版)》2011,17(6):446-449
The more unambiguous statement of the P versus NP problem and the judgement of its hardness, are the key ways to find the full proof of the P versus NP problem. There are two sub-problems in the P versus NP problem. The first is the classifications of different mathematical problems (languages), and the second is the distinction between a non-deterministic Turing machine (NTM) and a deterministic Turing machine (DTM). The process of an NTM can be a power set of the corresponding DTM, which proves that the states of an NTM can be a power set of the corresponding DTM. If combining this viewpoint with Cantor’s theorem, it is shown that an NTM is not equipotent to a DTM. This means that "generating the power set P(A) of a set A" is a non-canonical example to support that P is not equal to NP. 相似文献
9.
黄卫峰 《第二课堂(小学)》2009,(7)
After the retirement of Michael Jordan(乔丹),Kobe(科比)from Lakers(湖人队)is the only player who can be described as"great".He has signed a contract with sina.com to open his Chinese blog and establish his official website in Chinese in 2009,which will no doubt be a sensational event to both the Internet and the sports circles. 相似文献
10.
曾辉 《成都教育学院学报》2001,15(5):11-12
In Otto Jespersen‘s book the Philosophy of Grammar( 1951 ),the definition of formulas is mentioned: “a formula may be a whole sentence or a group of words, or it may be one word, or it may be only part of a word, that is not improtant,but it must always be something which to the actual speech- instinct is a unit which cannot be further analyzed or decomposed in the way a free combination can”(1951:24) .Thus proverbs belong to formulas, as the example “Handsome is that handsome does” given by Jespersen. 相似文献
11.
陈志高 《深圳信息职业技术学院学报》2006,4(4):48-51,59
蚂蚁算法在大规模网络寻找最优路径速度较慢,无法对最优路径进行数据流量控制。本文提出基于核心路由器的蚂蚁算法,通过从网络的各个核心路由器出发并行寻找最优路径,可以加快寻找最优路径的速度,并且能根据网络状况自动分流数据,这样可以保证网络的服务质量。 相似文献
12.
范秋生 《黄冈职业技术学院学报》2010,12(6):17-19
蚁群算法是继模拟退火算法、遗传算法、禁忌搜索算法、人工神经网络算法等启发式搜索算法之后的又一种应用于组合优化问题的算法。根据蚁群算法的特性,求解旅行商问题,利用仿真实验程序对蚁群求解旅行商问题进行模拟。 相似文献
13.
文中分析了传统的用于多峰函数优化问题的小生境遗传算法的特点和不足,基于免疫系统中的克隆选择原理,合理地构建了克隆选择算子及引入一种新的小生境技术,提出了一种解决多峰函数优化问题的小生境克隆选择算法.最后,实现了该算法对几种典型的多峰函数的优化仿真,结果表明该算法简单有效. 相似文献
14.
小生境遗传算法是近年来智能计算领域的研究热点之一,基于适应值共享的小生境遗传算法在解决多种优化问题时收到了很好的效果.该文对基于适应值共享小生境遗传算法的多种实现机制进行探索,并对不同类型算法各自的性能、适应情形和优缺点进行比较分析. 相似文献
15.
为了寻找更优的机器人移动路径,将沙猫群优化算法与三次样条插值方法进行融合,对沙猫群优化算法进行改进。在改进的沙猫群优化算法中,利用混沌映射的均匀性初始化种群以提高种群多样性;通过融合互利共生和莱维飞行策略减少局部最优解的消极影响,提高算法的收敛速度和精度。通过两种仿真实验对比6种优化算法的实验数据,结果表明,改进的沙猫群优化算法的最优解、最差解和平均解都优于对比算法,验证了改进沙猫群优化算法对于解决移动机器人路径规划问题的有效性和工程实用性。 相似文献
16.
TSP（旅行商问题）作为一种解决组合优化问题的有效方法,在近几十年来受到了广泛的研究。理论证明它是一个典型的NP难问题,为了更快捷地求解,候选集方法在多种求解算法比如LKH算法中都有用到,一般是用于产生一个接近局部最优的初始解,较少用于寻路过程中。本文提出了一种新的简单的候选集方法,它采用一种新的距离度量,更好地符合了对称TSP的寻路规则。将其应用于最大最小蚁群算法（MMAS）的寻路过程中,实验结果表明针对对称TSP问题,该方法能比基本的MMAS取得更好的性能。这种候选集方法也可以用于其他求解对称TSP问题的进化计算。 相似文献
17.
徐忠 《商丘师范学院学报》2005,21(5):81-85
遗传算法是一种基于生物自然选择与遗传机理的随机搜索与优化方法．近年来，由于遗传算法求解复杂优化问题的巨大潜力及其在工业工程领域的成功应用，这种算法受到了国内外学者的广泛关注．本文介绍了遗传算法的研究现状和基本原理，概述了它的理论和技术，并对遗传算法的性能作了分析．以推销员旅行问题为例来展示遗传算法在求解复杂优化问题上的优越性． 相似文献
18.
研究了电力系统的无功优化功问题,给出了结合电力市场实行的无功优化目标函数。在分析了遗传算法和蚁群算法各自优缺点的基础上,将遗传算法与蚁群算法融合,利用遗传算法的交叉、变异操作产生蚁群算法新的搜索路径,以此提高混合智能算法的全局搜索能力和收敛速度,并将混合智能算法应用于实例进行仿真。仿真结果表明,该混合智能算法具有快速的收敛速度和优良的全局优化能力。 相似文献
19.
索红军 《渭南师范学院学报》2012,(10):78-80
文章联系实际问题,结合旅行商问题和中国邮递员问题,提出赋权连通图中最小环路遍历路径以及求解该路径的方案.该方案参考最小生成树的普里姆算法,依据狄杰斯特拉算法,通过往返最短路径逐次比较,在赋权连通图中实现寻找最小环路遍历路径. 相似文献
20.
An extended discrete particle swarm optimization algorithm for the dynamic facility layout problem 总被引：2，自引：0，他引：2
Hassan Rezazadeh Mehdi Ghazanfari Mohammad Saidi-Mehrabad Seyed Jafar Sadjadi 《浙江大学学报(A卷英文版)》2009,10(4):520-529
We extended an improved version of the discrete particle swarm optimization （DPSO） algorithm proposed by Liao et al.（2007） to solve the dynamic facility layout problem （DFLP）. A computational study was performed with the existing heuristic algorithms, including the dynamic programming （DP）, genetic algorithm （GA）, simulated annealing （SA）, hybrid ant system （HAS）, hybrid simulated annealing （SA-EG）, hybrid genetic algorithms （NLGA and CONGA）. The proposed DPSO algorithm, SA, HAS, GA, DP, SA-EG, NLGA, and CONGA obtained the best solutions for 33, 24, 20, 10, 12, 20, 5, and 2 of the 48 problems from （Balakrishnan and Cheng, 2000）, respectively. These results show that the DPSO is very effective in dealing with the DFLP. The extended DPSO also has very good computational efficiency when the problem size increases. 相似文献