检索结果-南通市图书馆

External synchronization of two dynamical systems with uncertain parameters

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第3期53卷 731-740页

作者： HAN QingKai 1,SUN XiaoYu 2,YANG XiaoGuang 3.&WEN BangChun 1 1 School of mechanical engineering&Automation,Northeastern university,Shenyang 110004,China 2 School of Electrical engineering,Shenyang university of technology,Shenyang 110023.China 3.chool of mechanical engineering,The university of Birmingham,Birmingham,B15 2TT,UK 1. School of mechanical engineering & Automation Northeastern University Shenyang 110004 China2. School of Electrical Engineering Shenyang University of Technology Shenyang 110023 China3. School of Mechanical Engineering The University of Birmingham Birmingham B15 2TT UK

External synchronization is addressed as two or more dynamical systems with synchronous motions,which is also regarded as master-slave *** this paper,two dynamical systems,one employs a hysteretic term to model the friction phenomenon,the other involves a hardening stiffness component with the third order of displacement due to flexible deformation,are controlled to converge to the same *** control strategy is extended from feedback control for all parameters known to adaptive control for linear parameters unknown and all parameters *** slave system can keep synchronous motions with the movements of master via the designed control strategy even all the parameters are not *** stability of synchronization error,the transient process into synchronization and the effects of parameters on the designed controller using different control strategies are *** simulation results unfold the feasibility and effectiveness of this synchronization method.

关键词： controlled synchronization uncertain parameters hysteretic system Duffing system

Robustness and breakup of the spiral wave in a two-dimensional lattice network of neurons

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2010年第4期53卷 672-679页

作者： MA Jun 1,2, TANG Jun 2 , ZHANG AiHua 3.& JIA Ya 2 1 Department of Physics, Lanzhou university of technology, Lanzhou 73.050, China 2 Department of Physics, Central China Normal university, Wuhan 43.079, China 3.{3. of Electrical and Information engineering, Lanzhou university of technology, Lanzhou 73.050, China 1. Department of Physics Lanzhou University of Technology Lanzhou 730050 China2. Department of Physics Central China Normal University Wuhan 430079 China3. College of Electrical and Information Engineering Lanzhou University of Technology Lanzhou 730050 China

The robustness and breakup of spiral wave in a two-dimensional lattice networks of neurons are investigated. The effect of small- world type connection is often simplified with local regular connection and the long-range connection with certain probability. The network effect on the development of spiral wave can be better described by local regular connection and changeable long-range connection probability than fixed long-range connection probability because the long-range probability could be changeable in realistic biological system. The effect from the changeable probability for long-range connection is simplified by multiplicative noise. At first, a stable rotating spiral wave is developed by using appropriate initial values, parameters and no-flux boundary conditions, and then the effect of networks is investigated. Extensive numerical studies show that spiral wave keeps its alive and robust when the intensity of multiplicative noise is below a certain threshold, otherwise, the breakup of spiral wave occurs. A statistical factor of synchronization in two-dimensional array is defined to study the phase transition of spiral wave by checking the membrane potentials of all neurons corresponding to the critical parameters(the intensity of noise or forcing current)in the curve for factor of synchronization. The Hindmarsh-Rose model is investigated, the Hodgkin-Huxley neuron model in the presence of the channel noise is also studied to check the model independence of our conclusions. And it is found that breakup of spiral wave is easier to be induced by the multiplicative noise in presence of channel noise.

关键词： spiral wave factor of synchronization breakup multiplicative noise robustness

A new method to improve surface morphology of Ni-Fe-Mo-Co alloy electrode and its catalytic activity for HER

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第3期26卷 205-212页

作者： LUO Beiping REN Buye XU You ZHENG Yajie Department of Chemistry and Chemical engineering Hunan Institute of Science and Technology Yueyang 414000 China college of Metallurgical Science and engineering Central South University Changsha 410083 China Research Institute of Materials Science South China University of Technology Guangzhou 510640 China

A new pretreatment method has been developed to improve the catalytic activity of the Ni-Fe-Mo-Co alloy electrode for hydrogen evolution reaction （HER）. The procedure involves pre-electrolyzing the Ni-Fe-Mo-Co alloy electrode in 3.% KOH solution containing 10% potassium sodium tartrate at 70℃ for 2 h, until some of the Mo and Fe elements are leached out. The surface morphology of the Ni-Fe-Mo-Co alloy demonstrates a unique hive-like structure after the pre- treatment, which has the pore size in a nanometer range （about 50 nm）, a very large real surface area, and good stability. The results of the electrochemical studies show that compared to other similar electrode materials and the treated Ni-Fe-Mo-Co electrode by leaching method, the pre-treated Ni-Fe-Mo-Co electrode has a much lower overpotential and much higher exchange current density for HER. In addition, a long-term continuous electrolysis test with a current interruption shows that the Ni-Fe-Mo-Co alloy has excellent catalytic stability.

关键词： catalytic activity surface treatment Ni-Fe-Mo-Co alloy hydrogen evolution electrodeposition

Electron microscopy study of the sakhaite from endogenous borate deposit in Hunan, China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2004年第3期47卷 232-238页

作者： LIU Xiangwen1,2, YANG Guangming2, ZOU Huamin3. QU Jing1 & ZHAO Wenxia4 1. Graduate School, China university of Geosciences, Wuhan 43.074, China 2. Test Center, China university of Geosciences, Wuhan 43.074, China 3. Physics and technology {3., Wuhan university, Wuhan 43.072, China 4. Test Center, Zhongshan university, guangzhou 510275, China China Univ Geosci Grad Sch Wuhan 430074 Peoples R China China Univ Geosci Test Ctr Wuhan 430074 Peoples R China Wuhan Univ Phys & Technol Coll Wuhan 430072 Peoples R China Zhongshan Univ Test Ctr Guangzhou 510275 Peoples R China

Sakhaite specimens from an endogenous borate deposit in Hunan Province, China have been studied in detail by means of transmission electron microscopy (TEM). The selected area electron diffraction (SAED) patterns obtained with different crystal zone axes show that the crystal system is cubic, with a = 1.463.nm. The convergent beam electron diffraction (CBED) patterns indicate that the point group and space group of sakhaite is m3. and Fd3., respec-tively. The space group of synthetic sakhaite determined by Chichagov (1974) is F413.. The possible reasons why the space groups of the natural and the synthetic sakhaites are different are discussed.

关键词： sakhaite, space group, convergent beam electron diffraction (CBED).

Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(Materials Science) 2006年第4期21卷 146-149页

作者：霍凯成 Hubei Key Laboratory of Roadway Bridge & Structure engineering Wuhan University of TechnologyWuhan 430070China

By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved ： temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolation process should be taken into consideration in the same time. Proper chemical admixtures and mineral cornpasitions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

关键词： concrete coefficient of thermal expansion temperature-stress test

Early Hydration of Composite Cement with Thermal Activated Coal Gangue

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(Materials Science) 2010年第1期25卷 162-166页

作者：郭伟 Department of Material engineering Yancheng Institute of Technology Institute of Material Science and engineering Nanjing University of Technology

Composite cement samples were prepared by mixing clinker, gypsum with burnt coal gangues which was calcined at various temperatures. The mechanical strength and Ca（OH）2 content in the cement paste were tested, and the paste composition and microstructure were analyzed by thermogravimetry-differential thermal analysis （TG-DSC）, X-ray diffraction（XRD）, scanning electronic microscopy （SEM） and pore structure analysis. Results demonstrate that the thermal activated coal gangue could accelerate the early hydration of cement clinker obviously, which promotes the gangue hydration itself. The early hydrated products of the cement are C-S-H gel, Ca（OH）2 and AFt. The cement with 3.% （in mass） the gangue exhibits higher mechanical strength, and among all the cement samples the one with the gangue burnt at 700 ℃ displays the highest hydration rate, mechanical strength, the most gel pores and the lowest total porosity.

关键词： blended cement hydration microstructure hydration product

A new DNA algorithm to solve graph coloring problem

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第6期17卷 733-738页

作者： Jiang Xingpeng1, Li Yin2, Meng Ya3.and Meng Dazhi2(1. National Laboratory of Pattern Recognition,Institute of Automation, Chinese Academy of Sciences, Beijing 100080, China 2. college of Applied Sciences, Beijing university of technology, Beijing 100022, China 3. School of Science, Beijing Institute of technology, Beijing 100081, China) National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences Beijing 100080 China college of Applied Sciences Beijing University of Technology Beijing 100022 China School of Science Beijing Institute of Technology Beijing 100081 China

Using a small quantity of DNA molecules and little experimental time to solve complex problems successfully is a goal of DNA computing. Some NP-hard problems have been solved by DNA computing with lower time complexity than conventional computing. However, this advantage often brings higher space complexity and needs a large number of DNA encoding molecules. One example is graph coloring problem. Current DNA algorithms need exponentially increasing DNA encoding strands with the growing of problem size. Here we propose a new DNA algorithm of graph coloring problem based on the proof of four-color theorem. This algorithm has good properties of needing a relatively small number of operations in polynomial time and needing a small number of DNA encoding molecules (we need only 6R DNA encoding molecules if the number of regions in a graph is R).

关键词： DNA computing NP-hard problem graph coloring problem.

Alterations in DNA methylation and genome structure in two rice mutant lines induced by high pressure

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2006年第2期49卷 97-104页

作者： SHEN Sile1,3. WANG Zhenwei3. SHAN Xiaohui2, WANG Hua3. LI Ling3. LIN Xuyun2, LONG Likun2, WENG Kenan4, LIU Bao2 & ZOU Guangtian1 1. National Laboratory of Superhard Materials, Jilin university, Changchun 13.012, China 2. Institute of Genetics and Cytology, Northeast Normal university, Changchun 13.024, China 3. college of Life Science, Jilin university, Changchun 13.012, China 4. guangzhou Institute of Geochemistry, Chinese Academy of Sciences, guangzhou 510640, China 1. National Laboratory of Superhard Materials Jilin University Changchun 130012 China 3. college of Life Science Jilin University Changchun 130012 China 2. Institute of Genetics and Cytology Northeast Normal University Changchun 130024 China 4. guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

By using high-pressure treatment, two mutant lines were obtained from agenetically stable japonica rice cultivar Bijing3.. Genomic DNA of the mutant lines, together withthe original line (Bijing3.), was either undigested or digested by Hpa ⅡIMspⅠ, and then subjectedto molecular analysis using two markers, ISSR and RAPD. Results indicated that changes in the PCRamplification profiles of both markers are apparent in the two mutant lines compared with theoriginal rice cultivar, suggesting that there had been both sequence changes and DNA methylationmodifications in the mutant lines. southern blot analysis using diverse sequences, including twocellular genes (S2 and S3., a set of retrotransposons (Osr7, Osr3., Tos19 and more), and a MITEtransposon family (mPing and Pong), confirmed the results, and indicated that changes in DNAmethylation pattern, genomic structure, and possible activation of some transposons indeed occurredin the mutant lines. Moreover, these changes are stably maintained through selfed generations and indifferent organs. Thus, our results indicate that it is possible to obtain stable mutants in riceby high pressure treatments, and the molecular basis of the mutants may include both genetic andepigenetic changes. Therefore, high hydrostatic pressure seems a promising approach for plantmutagenesis.

关键词： DNA methylation, genomic changes, high pressure, mutagenesis, rice.

Development and Physical Properties of Film of Wheat Gluten Cross-linked by Transglutaminase

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(Materials Science) 2005年第1期20卷 78-82页

作者：王金水 college of Food and Bioengineering South China University of TechnologyGuang zhou 510641China The Faculty of Food engineering Henan University of TechnologyZhengzhou 450052China

Films were developed from the modified wheat glutens by microbial transglutamina se(MTGase, [E/S]=10u/g,15u/g and 20u/g) in order to improve physical and barri er properties of the *** was used as a *** films prepared from the modified-glutens by MTGase show a lower elongation at break(E) and a water vapor permeability(WVP), and a higher tensile strength(TS) than the nati ve gluten *** the modified gluten films by different concentrations of MT Gase are immersed in water at 25℃,their weight losses decreased significantly, and their water resistance increases obviously as expected, compared with the c ontrol gluten films. Moreover, an addition of glycerol as plasticizer greatly mo dified water vapor barrier and mechanical properties of the films.

关键词： wheat gluten microbial transglutaminase barrier properties tensile strengt h elongation at break