检索结果-南通市图书馆

Chinese Physics Letters 2003年第2期20卷 304-307页

作者：王煦景勤等 KeyLaboratoryofMetastableMaterialsScienceandTechnology YanshanUniversityQinhuangdao066004 CollegeofMaterialsScienceandEngineering YanshanUniversityQinhuangdao066004

The structure or short-range order of clusters in undercooled metallic melts is influenced, to some extent, by the interfacial free energy between the cluster and the melt. Analyses of the effects of interfacial energy on the cluster structure based on the Gibbs equation show a possibility that atoms in the clusters tend to be packed more loosely with the increasing cluster size (or the undercooling). Nucleation may occur, following these analyses, when clusters reach a definite size and atoms in the clusters relax to some extent to form the crystal structure. Indirect support to this viewpoint is provided by the present results of cluster-induced nucleation experiments on undercooled Ge73.7Ni26.3 alloy melts.

关键词： Nucleation

Mathematical Model for Fabrication of Micro-Structure Fibres

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2005年第5期22卷 1162-1165页

作者：周桂耀侯峙云李曙光侯蓝田 InstituteofInfraredOpticalFibresandSensors YanshanUniversityQinhuangdao066004

Using the classic principles of mechanics, we discuss the shape transformation of the micro-structure fibre preform under high temperature of the fibre drawing process, which leads to the theoretical relations among the structural diameter of the micro-structure fibre, the drawing technical parameter, and the physical constant of the micro-structure fibre material. The theoretic values are basically in agreement with the experimental results.

关键词： Microstructure

Supercontinuum Generation in Holey Microstructure Fibres with Random Cladding Distribution by Femtosecond Laser Pulses ＊

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2003年第8期20卷 1300-1302页

作者：李曙光侯蓝田冀玉领周桂耀 InstituteofInfraredOpticalFibresandSensors YanshanUniversityQinhuangdao066004

It is reported that supercontinuum spectrum from 440 to 1050nm can be generated in holey microstructure fibres (HMFs) with random cladding distribution by Ti:sapphire femtosecond laser pulses with central wavelength of 800nm. Based on the method of the effective refractive index and the analogy of step-index fibre, we have calculated the effective mode area and the group velocity dispersion (GVD). It is found that the HMFs have specifically ability of localizing light and controlling GVD. The mechanism of supercontinuum generation in the HMFs with random cladding distribution is that the balance between the GVD and the self-phase modulation in the anomalous dispersion region leads to formation of solitons and fission of high order solitons.

关键词： Group velocity dispersion

Stabilizing Unstable Equilibrium Point of Unified Chaotic Systems with Unknown Parameter Using Sliding Mode Control

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2004年第2期21卷 227-229页

作者：关新平何宴辉 InstituteofElectricalEngineering YanshanUniversityQinhuangdao066004

The control problem of a unified chaos is considered. Stabilizing unstable equilibrium point is achieved by a sliding mode controller based on parameter identification. The observer is applied to identify the unknown parameter of a unified chaotic system. Simulations are made and the results verify the validity of the proposed method.

关键词： Sliding mode control

Microstructures and Mechanical Properties of TiC_P/Al-4.5Cu-0.8Mg Composites by Direct Reaction Synthesis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2003年第5期19卷 447-449页

作者： MingzhenMA DayongCAI TianhuaWEI KeyLaboratoryofMetastableMaterialsScienceandTechnology YanshanUniversityQinhuangdao066004China CollegeofMaterialScienceandEngineering YanshanUniversityQinhuangdao066004China

Direct reaction synthesis (DRS), based on the principle of self-propagating high-temperature synthesis (SHS), is a new method for preparing participate metal matrix composites. TiCP/AI-4.5Cu-0.8Mg composites were fabricated by DRS. Participate composites were fabricated with Ti carbide (TiC) particles, generally less than 1.0μm. The reacted, thermal extruded samples exhibit a homogeneous distribution of fine TiC particles in AI-4.5Cu-0.8Mg matrix. Mechanical property evaluation of the composites has revealed a very high tensile strength relative to the matrix alloy. Fractographic analysis indicates ductile failure.

关键词： TiCp/Al-4.5Cu-0.8Mg composites Microstructure Mechanical property TiC particle

Synchronization of Uncertain Time Delay Chaotic Systems using the Adaptive Fuzzy Method

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2002年第8期19卷 1031-1034页

作者：关新平华长春 InstituteofElectricalEngineering YanshanUniversityQinghuangdao066004

We consider the synchronization problem of a class of first-order differential-delay chaotic systems. We utilize time-delay fuzzy logic systems to approximate continuous nonlinear time-delay functions, so that the precise mathematical model need not be known. Adopting the adaptive fuzzy control method, we construct a class of state feedback controllers which can render the closed-loop error systems to be asymptotically stable. We carry out simulations of synchronizing Mackey-Glass and logistic chaotic systems, and the results are reasonable.

关键词： Chaotic systems

Thermodynamic Analyses of the Solid-Liquid Interface and Growth Mode Transition in Undercooled Melts

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2003年第9期20卷 1622-1625页

作者：刘日平 KeyLaboratoryofMetastableMaterialsScienceandTechnology YanshanUniversityQinhuangdao066004

Free energy change for atoms transferred from liquid onto liquid-solid interface is calculated according to the structural model proposed by Jackson. Relationship among the change in free energy, the fraction of sites on the interface occupied by atoms and the interfacial undercooling is presented. This relationship can be used to judge the possible state that an interface may take, and to predict the corresponding crystal growth mode. For silicon and germanium, the experimentally observed growth mode transition from lateral growth at small undercooling to continuous growth at large undercooling is hardly to be explained by this thermodynamic calculation, which implies that the transition is possibly caused by some dynamic reasons. For nickel, crystallization is carried out only by the continuous mode, which is consistent with the experimental observations.

关键词： Thermoanalysis

Communication Scheme via Cascade Chaotic Systems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2004年第8期21卷 1441-1444页

作者：华长春关新平 InstituteofElectricalEngineering YanshanUniversityQinhuangdao066004

A new chaotic communication scheme is constructed. Different from the existing literature, cascade chaotic systems are employed. Two cascade modes are considered. First, we investigate the input to state cascade mode; cascade systems between different kinds of chaotic systems are considered. Then the parameter cascade case of chaotic system is studied. Under the different cases, the corresponding receivers are designed, which can succeed in recovering the former emitted signal. Simulations are performed to verify the validity of the proposed main results.

关键词： Chaotic systems

PROGRAM-PATTERN MULTIPOLE BOUNDARY ELEMENT METHOD FOR FRICTIONAL CONTACT

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2005年第1期18卷 76-82页

作者： YuChunxiao ShenGuangxian LiuDeyi CollegeofScience YanshanUniversityQinhuangdao066004China CollegeofMechanicalEngineering YanshanUniversityQinhuangdao066004China

A mathematical program is proposed for the highly nonlinear problem involving frictional contact. A program-pattern using the fast multipole boundary element method (FM- BEM) is given for 3-D elastic contact with friction to replace the Monte Carlo method. A new optimized generalized minimal residual (GMRES) algorithm is presented. Numerical examples demonstrate the validity of the program-pattern optimization model for node-to-surface contact with friction. The GMRES algorithm greatly improves the computational efciency.

关键词： nonlinear programming GMRES algorithm node-to-surface contact FM-BEM

RELIABILITY-BASED DESIGN AND ANALYSIS ON HYDRAULIC SYSTEM FOR SYNTHETIC RUBBER PRESS

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2005年第2期18卷 159-162页

作者： YaoChengyu ZhaoJingyi CollegeofElectricalEngineering YanshanUniversityQinhuangdao066004China CollegeofMechanicalEngineering YanshanUniversityQinhuangdao066004China

To overcome the design limitations of traditional hydraulic control systemfor synthetic rubber press and such faults as high fault rate, low reliability, highenergy-consuming and which always led to shutting down of post-treatment product line for syntheticrubber, brand-new hydraulic system combining with PC control and two-way cartridge valves for thepress is developed, whose reliability is analyzed, reliability model of the hydraulic system for thepress is established by analyzing processing steps, and reliability simulation of each step and thewhole system is carried out by software MATLAB, which is verified through reliability test. Thefixed time test has proved not that theory analysis is sound, but the system has characteristics ofreasonable design and high reliability, and can lower the required power supply and operationalenergy cost.

关键词： Synthetic rubber près Hydraulic system Reliability Simulation Fixedtime test