检索结果-南通市图书馆

Tricritical and Critical Exponents in Microcanonical Ensemble of Systems with Long-Range Interactions

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2016年第12期65卷 638-642页

作者： liang-sheng Li Science and Technology on Electromagnetic Scattering Laboratory Beijing 100854 China

We explore the tricritical points and the critical lines of both Blume Emery Griffiths and Ising model within long-range interactions in the microcanonical *** K = Kmtp,the tricritical exponents take the valuesβ = 1/4,1 =γ^-≠γ^+ = 1/2 and 0 =α^-≠α^+ =-1/2,which disagree with classical(mean ffeld) *** K > Kmtp,the phase transition becomes second order and the critical exponents have classical values except close to the canonical tricritical parameters(Kctp),where the values of the critical expoents become β = 1/2,1 = γ^-≠γ^+= 2and 0 =α^-≠α^+ = 1.

关键词： long-range interation critical exponent microcanonical ensemble

A Comparative Study of Numerical Models for Wave Propagation and Setup on Steep Coral Reefs

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2019年第4期33卷 424-435页

作者： ZHANG Shan-ju ZHU liang-sheng ZOU Kai South China University of Technology School of Civil Engineering and Transportation

Complex factors including steep slopes, intense wave breaking, large bottom friction and remarkable wave setup should be considered while studying wave propagation over coral reefs, and how to simulate wave propagation and setup on coral reefs efficiently has become a primary focus. Several wave models can be used on coral reefs as have been published, but further testing and comparison of the reliability and applicability of these models are needed. A comparative study of four numerical wave models (i.e., FUNWAVE-TVD, Coulwave, NHWAVE and ZZL18) is carried out in this paper. These models’ governing equations and numerical methods are compared and analyzed firstly to obtain their differences and connections;then the simulation effects of the four wave models are tested in four representative laboratory experiments. The results show that all four models can reasonably predict the spectrum transformation. Coulwave, NHWAVE and ZZL18 can predict the wave height variation more accurately;Coulwave and FUNWAVE-TVD tend to underestimate wave setup on the reef top induced by spilling breaker, while NHWAVE and ZZL18 can predict wave setup relatively accurately for all types of breakers;NHWAVE and ZZL18 can predict wave reflection by steep reef slope more accurately. This study can provide evidence for choosing suitable models for practical engineering or establishing new models.

关键词： coral reefs steep slope Boussinesq equations wave propagation and setup wave breaking numerical simulation comparative study

Mechanical and magnetic hysteresis as indicators of the origin and inception of fatigue damage in steel

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第8期11卷 580-586页

作者： sheng BAO Wei-liang JIN Ming-feng HUANG Institute of Structural Engineering Zhejiang University Hangzhou 310058 China

N2 and N3 are known as the transition points of the three principal stages of fatigue: initial accommodation, accretion of damage and terminal fatigue. Many experiments show that the ratios of N2/Nf and N3/Nf tend to be stable even though the specific N2 and N3 values may fluctuate widely. The primary goal of this research is to study the piezomagnetic field surrounding AISI 1018 steel specimen under repeated loads and to find the ratio values of N2/Nf and N3/Nf by analyzing 11 sets of low-cycle fatigue data. An MTS-810 testing system with a peak capacity of 222 kN was used to obtain the data which consisted of stress, strain, and piezomagnetic field. A computer program was constructed to track the evolution of the piezomagnetic field and re- gression analysis was carried out to determine N2 and N3 values. It was observed that there exists a consistent relationship between N2 and Nf. The apparent invariance of the ratio N2/Nf implies that N2 may be identified as an index of performance in the early loading response of a specimen that forecasts its fatigue life, Nf. It has been demonstrated that measurements of the magnetic and mechanical hysteresis can yield significant insights into the various stages of the development of a fatigue critical microstructure which culminates in complete rupture of the material.

关键词： Piezomagnetic effects. Fatigue damage. Mechanical hvsteresis. Magnetic hysteresis

Low-temperature molten salt synthesis and luminescence properties of Eu(Ⅲ)-based coordination polymer nanosheets

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第3期40卷 728-735页

作者： Lei Wang Hao Liu Shuang Huang sheng-liang Zhong College of Chemistry and Chemical Engineering Jiangxi Normal UniversityNanchang 330022China

In this work,Eu(III)-based coordination polymer(EuCP) nanosheets were successfully synthesized using tetrabutylammonium bromide(TBAB) as low-temperature molten salt(LMS),terephthalic acid(PTA) and pyromellitic acid(PMA) as organic building blocks at 160℃.X-ray diffraction(XRD),Fourier transform infrared(FTIR),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and thermogravimetry and differential thermal analysis(TG-DTA) were used to characterize the obtained *** show that the nanosheets have an average size of 200 nm and a thickness of about 50 *** effect of reaction temperature,reaction time and molar ratio of Eu^(3+)/PTA/PMA on the preparation was *** turns out that all of them have great effect on morphology and size of the final *** excited with 315 nm,strong emission centering at 617 nm is ***,this synthetic methodology may offer a new alternative in the preparation of rare earth nanomaterials.

关键词： Molten salt Coordination polymer Rare earth Nanosheets

Improved time-optimal B-spline feedrate scheduling for NURBS tool paths in CNC machining

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2023年第1期11卷 111-129页

作者： Yang Li Fu-sheng liang Lei Lu Cheng Fan School of Mechanic Engineering Northeast Electric Power UniversityJilin132012JilinPeople’s Republic of China Jiangsu Provincial Key Laboratory of Advanced Robotics and Collaborative Innovation Center of Suzhou Nano Science and Technology College of Mechanical and Electrical EngineeringSoochow UniversitySuzhou215021JiangsuPeople’s Republic of China

Feedrate scheduling in computer numerical control(CNC)machining is of great importance to fully develop the capabilities of machine tools while maintaining the motion stability of each *** and time-optimal feedrate scheduling plays a critical role in improving the machining efficiency and precision of complex surfaces considering the irregular curvature characteristics of tool paths and the limited drive capacities of machine *** study develops a general feedrate scheduling method for non-uniform rational B-splines(NURBS)tool paths in CNC machining aiming at minimizing the total machining time without sacrificing the smoothness of feed *** feedrate profile is represented by a B-spline curve to flexibly adapt to the frequent acceleration and deceleration requirements of machining along complex tool *** time-optimal B-spline feedrate is produced by continuously increasing the control points sequentially from zero positions in the bidirectional scanning and sampling *** required number of knots for the time-optimal B-spline feedrate can be determined using a progressive knot insertion *** improve the computational efficiency,the B-spline feedrate profile is divided into a series of independent segments and the computation in each segment can be performed *** proposed feedrate scheduling method is capable of dealing with not only the geometry constraints but also high-order drive constraints for any complex tool path with little computational *** and machining experiments are conducted to verify the effectiveness and superiorities of the proposed method.

关键词： B-spline feedrate Non-uniform rational B-splines(NURBS)tool path Knot insertion Bidirectional scanning Computer numerical control(CNC)machining

LiFePO_4 doped with magnesium prepared by hydrothermal reaction in glucose solution

维普期刊数据库评论

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 Chemical Letters 2008年第3期19卷 345-349页

作者： Xiu Qin Ou Guang Chuan liang Jin sheng liang sheng Zhao Xu Xia Zhao Institute of Power Source ＆ Ecomaterials Science Box 1055 Hebei University of Technology Tianjin 300130 China

Lithium iron phosphate （LiFePO4） doped with magnesium was hydrothermally synthesized from commercial LiOH, FeSO4, H3PO4 and MgSO4 with glucose as carbon precursor in aqueous solution. The samples were characterized by X-ray powder diffraction, scanning electron microscopy and constant charge-discharge cycling. The results show that the synthesized powders have been in situ coated with carbon precursor produced from caramel reaction of glucose. At ambient temperature （28±2℃）, the electrochemical performances of LiFePO4 prepared exhibit the high discharge capacity of 135 mAh g^-1 at 5C and good capacity retention of 98% over 90 cycles. The excellent electrochemical performances should be correlated with the intimate contact between carbon and LiFePO4 primary and secondary particles, resulting from the in situ formation of carbon precursor/carbon, leading to the increase in conductivity of LiFePO4.

关键词： Lithium iron phosphate Mg doping Hydrothermal reaction Glucose Carbon coated

Content delivery network and its regulation

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2006年第4期13卷 98-101页

作者： PENG Jiu-sheng liang Xiong-jian School of Economics and Management Beijing University of Posts and Telecommunications Beijing 100876 China

First, this article provides an introduction to the content delivery network （CDN）, which has wide prospects but is still in its early stages in China. Second, this article depicts the present situation and the developing characteristics of CDN in China. Elaborating on the above-mentioned two points, this article identifies the numerous problems that are encountered during the development of CDN, such as indistinct service positioning and the hidden troubles of information security. Finally, this article presents several countermeasures for handling the problems, such as opening the market widely, making a rational service positioning, strengthening the regulation on information security, and punishing illegal operations and unfair competition.

关键词： CDN Intemet information security

RESEARCH ON WAVE FORCES ACTING ON THE UNIT LENGTH OF A VERITICAL BREAKWATER BY TESTS AND A NUMERICAL MODEL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第5期18卷 512-519页

作者： HU Jin-peng YU Yu-xiu ZHU liang-sheng LED South China Sea Institute Oceanology Chinese Academy of Sciences Guangzhou 510301 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China Graduate School of the Chinese Academyof Sciences Beijing 100049China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China

Comprehensive 3D model tests and numerical simulation were performed to study the effects of wave obliquity and multidirectionality on the wave forces acting on vertical breakwaters. The variation of wave forces acting on the unit length of a breakwater was analyzed, and the results were compared with Goda＇s formula. A numerical model based on a short-crest wave system was used to model regular wave forces for practical use, which showed good results for those waves with small incident angles.

关键词： vertical breakwater uni- and multidirectional irregular waves wave forces acting on the unit length short-crest wave model

Waves of 3D Marine Structures Slamming at Different Initial Poses in Complex Wind-Wave-Flow Environments

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2016年第5期30卷 772-785页

作者： ZHU liang-sheng YU Long-fei School of Civil Engineering and Transportation South China University of Technology Guangzhou 510640 China School of Marine Engineering Guangzhou Maritime University Guangzhou 510725 China

Aimed at the hydrodynamic response for marine structures slamming into water, based on the mechanism analysis to the slamming process, and by combining 3D N-S equation and k-ε turbulent kinetic equation with structure fully 6DOF motion equation, a mathematical model for the wind-fluid-solid interaction is established in 3D marine structure slamming wave at free poses and wind-wave-flow complex environments. Compared with the results of physical model test, the numerical results from the slamming wave well correspond with the experimental results. Through the mathematical model, the wave-making issue of 3D marine structure at initial pose falls into water in different complex wind, wave and flow environments is investigated. The research results show that various kinds of natural factors and structure initial poses have different influence on the slamming wave, and there is an obvious rule in this process.

关键词： marine structures slamming wave initial pose natural background 6DOF