共查询到20条相似文献,搜索用时 31 毫秒
1.
MO Zhongxi ZENG Tao 《武汉大学学报:自然科学英文版》2006,11(3):498-502
In view of the fact that the problem of sorting unsigned permutation by reversal is NP-hard, while the problem of sorting signed permutation by reversal can be solved easily, in this paper, we first transform an unsigned permutation of length n,π (π1 ,… ,πn), into a set S(π) containing 2^n signed permutations, so that the reversal distance of π is equal to the reversal distance of the optimal signed permutation in S(π). Then analyze the structural features of S(π) by creating a directed graph and induce a new computing model of this question. Finally, an improved genetic algorithm for solving the new model is proposed. Experimental results show that the proposed model and algorithm is very efficient in practice. 相似文献
2.
ZhangNing LiuHai-lin YuZhu-xing XiongRui ShiJing 《武汉大学学报:自然科学英文版》2004,9(1):55-58
The characteristics of electronic transport properties: behaviors of magnetization curve and magnetic relaxation of a typical normal superconductor 2H-NbSe2 are investigated. The results show that Tc and △Tc of the samples are 7. 2,0. 18 K, indicating that superconducting energy gap at zero temperature is 1. 1 meV. No fish tail shape is found in the magnetization curves at several temperatures. The relationship between remnant magnetic moment and time reveals that the magnetic flux creep of the sample agrees with the Kim-Anderson thermal activation model with the relaxation rate S=0.000 36 at T=6 K. 相似文献
3.
In this paper, algorithms of constructing wavelet filters based on genetic algorithm are studied with emphasis on how to construct
the optimal wavelet filters used to compress a given image,due to efficient coding of the chromosome and the fitness function,
and due to the global optimization algorithm, this method turns out to be perfect for the compression of the images.
Foundation item: Supported by the Natural Science Foundation of Education of Hunan Province(21010506)
Biography: Wen Gao-jin( 1978-), male, Master candidate, research direction: evolutionary computing. 相似文献
4.
This paper presents a two-phase genetic algorithm (TPGA) based on the multi-parent genetic algorithm (MPGA). Through analysis
we find MPGA will lead the population’s evolvement to diversity or convergence according to the population size and the crossover
size, so we make it run in different forms during the global and local optimization phases and then forms TPGA. The experiment
results show that TPGA is very efficient for the optimization of low-dimension multi-modal functions) usually we can obtain
all the global optimal solutions.
Foundation item: Supported by the National Natural Science Foundation of China (70071042, 60073043,60133010)
Biography: Huang Yu-zhen ( 1977-), female, Master candidate, research direction; evolution computation. 相似文献
5.
WangShao-wei ZhuQiu-ping YangYong 《武汉大学学报:自然科学英文版》2004,9(1):59-62
Echo canceller generally needs a double-talk detector which is used to keep the adaptive filter from diverging in the appearance of near-end speech. In this paper we adopt a new double-talk detection algorithm based on ι2 norm to detect the existence of near-end speech in an acoustic echo canceller. We analyze this algorithm from the point of view of functional analysis and point out that the proposed double-talk detection algorithm has the same performance as the classic one in a finite Banach space. The remarkable feature of this algorithm is its higher accuracy and better computation complexity. The fine properties of this algorithm are confirmed by computer simulation and the application in a multimedia communication system. 相似文献
6.
Let S be a family of binary sequences constructed from interleaved construction. The linear spans of binary sequences in S are studied in this paper. In order to achieve the largest linear span, a criterion is presented for the base sequences with periodp, where p is a prime and 2 is a primitive root modulop2. It is shown that any sequence in S has the largest linear span under the criterion. Moreover, such base sequences can be chosen easily. 相似文献
7.
KOU Yue SHEN Derong YU Ge LI Dong NIE Tiezheng 《武汉大学学报:自然科学英文版》2007,12(5):830-834
Caching is an important technique to enhance the efficiency of query processing. Unfortunately, traditional caching mechanisms are not efficient for deep Web because of storage space and dynamic maintenance limitations. In this paper, we present on providing a cache mechanism based on Top-K data source (KDS-CM) instead of result records for deep Web query. By integrating techniques from IR and Top-K, a data reorganization strategy is presented to model KDS-CM. Also some measures about cache management and optimization are proposed to improve the performances of cache effectively. Experimental results show the benefits of KDS-CM in execution cost and dynamic maintenance when compared with various alternate strategies. 相似文献
8.
SVM(support vector machine)算法求解支持向量的过程涉及到N阶矩阵的计算,N为样本的个数,当样本数量很大时,高阶矩阵的计算将需要消耗大量运算时间;同时,SVM模型性能依赖于惩罚参数与核参数的优化,传统的循环验证参数优化法,时间复杂度高.为了解决上面两方面的问题,笔者采用凸包算法对训练样本进行稀疏化,同时通过遗传算法优化选择惩罚参数与核参数,提出了一种高性能的SVM模型训练算法. 相似文献
9.
SU MaoWen FANG YuLing TAO WanQiang YAN GuoZeng MA WanE ZHANG ZhongNing 《科学通报(英文版)》2008,53(4):555-560
Pheromone gland extracts of the fall webworm, Hyphantria cunea (Lepidoptera: Arctiidae) were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Based on comparison of retention times and mass spectra of synthetic standards, four compounds were identified as (9Z,12Z)-octadecadienal, (9Z,12Z,15Z)-octadecatrienal, (3Z,6Z,9S, 10R)-9,10-epoxy-3,6-heneico- sadiene and (3Z,6Z,9S,10R)-9,10-epoxy-1,3,6-heneicosatriene with a ratio of 2:33.6:58.4:6. Trapping tests showed that quaternary blend of these compounds was highly attractive to male H. cunea. Unitraps baited with the quaternary blend loading of 200-300 μg on a gray rubber septum were very effective for monitoring H. cunea populations. 相似文献
10.
XU Yun SU Chunjiang LIU Xingliang MAN Zhenchuang LI Ping . Institute of Mountain Hazards Environment Chinese Academy of Sciences Chengdu Sichuan China . Graduate University of Chinese Academy of Sciences Beijing China . College of Bioengineering Southwest Jiaotong University Chengdu Sichuan China 《武汉大学学报:自然科学英文版》2006,11(4):929-936
0IntroductionThere are luxuriant biotic resources in PanxiArea,where mineral resources,hydraulic re-source and biotic resources are preponderant.Thedevelopment of Panxi Area began withthe exploita-tion of mineral resources,which has established asolidfoundationfor the development of Panxi Area.Withthe consumption of the mineral resources,be-ing a kind of nonrenewable resource,the mineral in-dustry contributes less and less to the developmentof Panxi Area and does more and more harmto en-vir… 相似文献
11.
QI Chang WANG Gaofeng SHI Xinzhi 《武汉大学学报:自然科学英文版》2007,12(6):1051-1056
In this paper, we study the interconnect buffer and wiresizing optimization problem under a distributed RLC model to optimize not just area and delay, but also crosstalk for RLC circuit with non-monotone signal response. We present a new multiobjective genetic algorithm(MOGA) which uses a single objective sorting(SOS) method for constructing the non-dominated set to solve this multi-objective interconnect optimization problem. The MOGA/SOS optimal algorithm provides a smooth trade-off among signal delay, wave form, and routing area. Furthermore, we use a new method to calculate the lower bound of crosstalk. Extensive experimental results show that our algorithm is scalable with problem size. Furthermore, compared to the solution based on an Elmore delay model, our solution reduces the total routing area by up to 30%, the delay to the critical sinks by up to 25%, while further improving crosstalk up to 25.73% on average. 相似文献
12.
In Zhang's recent works,a second-order Mehrotra-type predictor-corrector algorithm for linear optimization was extended to semidefinite optimization and derived that the algorithm for semidefinite optimization had O(n~(3/2)log(X~0)~T·S~0/ε) iteration complexity based on the NT direction as Newton search direction. In this paper, we extend the second-order Mehrotra-type predictor-corrector algorithm for linear optimization to semidefinite optimization and discuss the polynomial convergence of the algorithm by modifying the corrector direction and new iterates. It is proved that the iteration complexity is reduced to O(n~(3/2)log(X~0)~T·S~0/ε), which coincides with the currently best iteration bound of Mehrotra-type predictor-corrector algorithm for semidefinite optimization. 相似文献
13.
WANG Chunxiang FEI Pusheng 《武汉大学学报:自然科学英文版》2007,12(3):417-420
This paper discusses the total irredundance relations between the graph G and its clone-contraction graph H, that is, let H be the clone-contraction graph of G and v1,v2,...,vk be all contraction vertices ofH. IfS is a maximal total irredundant set of H such that A = S ∩ {V1,V2,…,Vk} contains as few vertices as possible, then S'= S-A is the maximal total irredundant set of G. Furthermore, we obtain the bound of the total irredundance A(G) number: irt ≤△(G)/2△(G)+1 n, which n is the order of graph G, and △(G) is maximum degree in G. 相似文献
14.
HE Xiaoxia MING Ruixing HU Yijun 《武汉大学学报:自然科学英文版》2007,12(3):412-416
Let u ∈ R ,for any ω 〉 0, the processes X^ε = {X^ε(t); 0 ≤ t≤ 1} are governed by the following random evolution equations dX^ε(t)= b(X^ε(t),v(t))dt-εdSt/ε, where S={St; 0≤t≤1} is a compound Poisson process, the process v={v(t); 0≤t≤1} is independent of S and takes values in R^m. We derive the large deviation principle for{(X^ε,v(.)); ε〉0} when ε↓0 by approximation method and contraction principle, which will be meaningful for us to find out the path property for the risk process of this type. 相似文献
15.
在氢气快速加注过程中,由于氢气的快速压缩及焦耳-汤普逊效应会导致气瓶内部温度急剧上升导致气瓶失效,从而产生安全隐患。针对3级储氢系统,建立了高压氢气快速加注过程的数学模型,用于分析车载氢气瓶在不同工作环境中的温升效应。结果显示加氢站储氢系统的控制压力切换点和预冷系统的控制温度对氢气最终状态影响较大。据此,以压力切换点和预冷温度为优化参数,预冷能耗、加注时间及氢气瓶最终氢气状态SOC为优化目标建立了多目标优化模型,结果表明该方法可以在尽可能减小预冷能耗和提高SOC的基础上完成高压氢气的快速加注。 相似文献
16.
【目的】为探讨灰毛豆属植物Tephrosia purpurea化学成分中的查尔酮类化合物,对其枝、叶部位进行化学成分分离及结构解析。【方法】采用乙醇提取、溶剂萃取、柱层析分离方法得到多种灰毛豆属T.purpurea化学成分,并用波谱分析手段对其进行结构表征。【结果】从灰毛豆属T.purpurea中共分离鉴定出11个查尔酮类化合物,分别为elatadihydrochalcone(1),spinochalcone A(2),3′,5′-diisopentenyl-2′,4′-dihydroxychalcone(3),candidachalcone(4),O-methylpongamol(5),(+)-tephrosone(6),spinochalcone C(7),epoxyobovatachalcone(8),tunicatachalcone(9),crassichalone(10),(S)-elatadihydrochalcone(11)。【结论】以上化合物均为查尔酮,且均属首次从该植物中分离得到。 相似文献
17.
CHEN Gang~ FAN Yun~ YUAN Yuan~ . School of Mathematics Statistics Wuhan University Wuhan Hubei China . School of Mathematics Statistics Central China Normal University Wuhan Hubei China . School of Computer Wuhan University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2006,11(2):339-342
0Introduction LetGbeafinitegroupoforder|G|=g,andletR(G)denotethecharacterringofG,whichisgeneratedbyalltheirreduciblecomplexcharactersofG.LetZbetherationalintegerringandNthesetofnatural numbers,andletZ[ω]betheintegralextensiongeneratedbyaprimitiveg throotωofunity.SupposethatSisasubringof thealgebraicnumberfieldsuchthatZ[ω]S.πisasetofra tionalprimenumbersdefinedasfollowsπ={p|pisarationalprimenumbersuchthatp-1S}.Definition1WecallthataconjugacyclassCofthefinite groupGisaπregularconju… 相似文献
18.
In this paper, a new algorithm for solving multimodal function optimization problems-two-level subspace evolutionary algorithm
is proposed. In the first level, the improved GT algorithm is used to do global recombination search so that the whole population
can be separated into several niches according to the position of solutions; then, in the second level, the niche evolutionary
strategy is used for local search in the subspaces gotten in the first level till solutions of the problem are found. The
new algorithm has been tested on some hard problems and some good results are obtained.
Foundation item: Supported by the National Natural Science Foundation of China (70071042, 60073043, 60133010).
Biography: Li Yan( 1974-), female, Ph. D candidate, research interest: evolutionary computation. 相似文献
19.
Based on the Dyson expansion theory, a microscopic approach of sdgIBM-1 is presented and applied to nucleus154Gd in this paper. The energy spectra andE2 transition have been calculated. Good agreement is obtained in comparison with experimental results.
Foundation item: Supported by the Foundation of Administration of Education of China
Biography: Sang Jian ping (1959), male. Ph. D. Professor, research direction: nuclear physics 相似文献