检索结果-南通市图书馆

The magnetic properties and magnetocaloric effects in binary R-T(R = Pr,Gd,Tb,Dy,Ho,Er,Tm;T = Ga,Ni,Co,Cu)intermetallic compounds

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第2期26卷 1-41页

作者： Xin-Qi Zheng bao-Gen shen School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Institute of Physics Chinese Academy of Sciences and University of Chinese Academy of Sciences Beijing 100190 China

In this paper, we review the magnetic properties and magnetocaloric effects（MCE） of binary R–T（R = Pr, Gd, Tb,Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series, R_（12）Co_7 series, R_3 Co series and RCu_2series）, which have been investigated in detail in the past several years. The R–T compounds are studied by means of magnetic measurements, heat capacity measurements, magnetoresistance measurements and neutron powder diffraction measurements. The R–T compounds show complex magnetic transitions and interesting magnetic *** types of magnetic transitions are investigated and confirmed in detail by multiple approaches. Especially, most of the R–T compounds undergo more than one magnetic transition, which has significant impact on the magnetocaloric effect of R–T compounds. The MCE of R–T compounds are calculated by different ways and the special shapes of MCE peaks for different compounds are investigated and discussed in detail. To improve the MCE performance of R–T compounds,atoms with large spin（S） and atoms with large total angular momentum（J） are introduced to substitute the related rare earth atoms. With the atom substitution, the maximum of magnetic entropy change（？SM）, refrigerant temperature width（Twidth）or refrigerant capacity（RC） is enlarged for some R–T compounds. In the low temperature range, binary R–T（R = Pr, Gd,Tb, Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series,R_（12）Co_7 series, R_3 Co series and RCu_2series） show excellent performance of MCE, indicating the potential application for gas liquefaction in the future.

关键词： magnetocaloric effect magnetic entropy change magnetic property neutron diffraction magnetic structure

New chaotic system and its hyperchaos generation

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2009年第6期20卷 1179-1187页

作者： bao Bocheng Liu Zhong xu Jianping Dept. of Electronic Engineering Nanjing Univ. of Science and Technology Nanjing 210094 P. R. China School of Electrical and Information Engineering Jiangsu Teachers Univ. of Technology Changzhou 213001 P. R. China School of Electrical Engineering Southwest Jiaotong Univ. Chengdu 610031 P. R. China

To seek for lower-dimensional chaotic systems that have complex topological attractor structure with simple algebraic system structure, a new chaotic system of three-dimensional autonomous ordinary differential equations is presented. The new system has simple algebraic structure, and can display a 2-scroll attractor with complex topological structure, which is different from the Lorenz＇s, Chen＇s and Lu¨＇s attractors. By introducing a linear state feedback controller, the system can be controlled to generate a hyperchaotic attractor. The novel chaotic attractor, hyperchaotic attractor and dynamical behaviors of corresponding systems are further investigated by employing Lyapunov exponent spectrum, bifurcation diagram, Poincar′e mapping and phase portrait, etc., and then verified by simulating an experimental circuit.

关键词： chaotic system attractor chaos hyperchaos.

Perceptual importance analysis for H.264/AVC bit allocation

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) 2008年第2期9卷 225-231页

作者： Gui-xu LIN Shi-bao ZHENG Institute of lmage Comm. ＆ Info. Processing Dept. of Electronic Engineering Shanghai Jiao Tong University Shanghai 200240 China Shanghai Key Laboratory of Digital Media Processing and Transmissions Shanghai Jiao Tong University Shanghai 200240 China

The existing H.264/AVC rate control schemes rarely include the perceptual *** a result,the im-provements in visual quality are hardly comparable to those in peak signal-to-noise ratio(PSNR).In this paper,we propose a perceptual importance analysis scheme to accurately abstract the spatial and temporal perceptual characteristics of video *** we perform bit allocation at macroblock(MB)level by adopting a perceptual mode decision scheme,which adaptively updates the Lagrangian multiplier for mode decision according to the perceptual importance of each *** results show that the proposed scheme can efficiently reduce bit rates without visual quality degradation.

关键词： Visual quality Human visual system Rate control H.264/AVC

Memristive cyclic three-neuron-based neural network with chaos and global coexisting attractors

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2022年第11期65卷 2582-2592页

作者： bao Han CHEN ZhuGuan CAI JianMing xu Quan bao BoCheng School of Microelectronics and Control Engineering Changzhou UniversityChangzhou 213164China

It has been documented that a cyclic three-neuron-based neural network with resistive synaptic weights cannot exhibit *** this end,a memristive cyclic three-neuron-based neural network is presented using a memristive weight to substitute a resistive *** memristive cyclic neural network always has five equilibrium points within the parameters of interest,and their stability analysis shows that they are one index-2 saddle-focus,two index-1 saddle-foci,and two stable node-foci,*** analyses are performed for the memristive cyclic neural network by several numerical simulation *** results demonstrate that the memristor synapse-based neural network with the simplest cyclic connection can not only exhibit chaos,but also present global coexisting attractors composed of stable points and unstable periodic or chaotic orbits under different initial ***,with the designed implementation circuit,Multisim circuit simulations and hardware experiments are executed to validate the numerical simulations.

关键词： memristive weight cyclic neural network chaos coexisting attractors hardware experiment

Model-free method for LQ mean-field social control problems with one-dimensional state space

在线全文

学校读者我要写书评

暂无评论

Control Theory and Technology 2024年第3期22卷 479-486页

作者： Zhenhui xu Tielong shen School of Engineering Tokyo Institute of TechnologyTokyo 152-8550Japan Department of Engineering and Applied Sciences Sophia UniversityTokyo 102-8554Japan

This paper presents a novel model-free method to solve linear quadratic(LQ)mean-field control problems with one-dimensional state space and multiplicative *** focus is on the infinite horizon LQ setting,where the conditions for solution either stabilization or optimization can be formulated as two algebraic Riccati equations(AREs).The proposed approach leverages the integral reinforcement learning technique to iteratively solve the drift-coefficient-dependent stochastic ARE(SARE)and other indefinite ARE,without requiring knowledge of the system dynamics.A numerical example is given to demonstrate the effectiveness of the proposed algorithm.

关键词： Mean-field control Social optima Infinite horizon Reinforcement learning

Synthesis of Dialkyl-substituted Terminal Olefin

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 2005年第9期16卷 1213-1216页

作者： shen Yong REN bao Jian shen Qiao Xia GUO State Key Laboratory of Heavy Oil Processing The Key Laboratory of Catalysis of CNPC andFaculty of Chemical Science and Engineering China University of Petroleum Beijing 102249

Dialkyl-substituted terminal olefins were synthesized from the coupling reaction of a-olefins which were catalyzed by zirconocene dichloride/methylalumoxane （MAO） catalyst system under mild condition. High yield was gained and no other oligmer was detected. It was found that the ratio of AI/Zr is responsible for the selectivity of product.

关键词： Zirconocene dichloride methylalumoxane dialkyl-substituted terminal olefin coupling reaction

Floating Zone Growth and Thermionic Emission Property of Single Crystal CeB_(6)

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2011年第8期28卷 318-321页

作者： bao Li-Hong ZHANG Jiu-Xing ZHOU shen-Lin ZHANG Ning xu Hong Key Laboratory of Advanced Functional Materials Ministry of Education College of Materials Science and EngineeringBeijing University of TechnologyBeijing 100124 Institute of Laser Engineering Beijing University of TechnologyBeijing 100124

Large-sized and high-quality cerium hexaboride(CeB6)single crystals are successfully grown by the optical floating zone *** structure,chemical composition and thermionic emission properties of the crystal are characterized by x−ray diffraction,x-ray fluorescence and emission measurements,*** on the observation of single crystal diffraction,the relative density of feed rods has a great effect on the quality of the grown *** thermionic emission measurement results show that the emission current density of the single crystal is 47.1 A/cm^(2) at 1873 K with an applied voltage of 1 kV,which is about two times larger than the value for polycrystalline *** single crystal possesses excellent emission current ***,it is expected that CeB6 single crystal is a very promising material for thermionic cathode applications.

关键词： stability crystal Crystal

Effects of solution and aging treatments on microstructures and mechanical properties of AZ61 magnesium alloy welded joints

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

Rare Metals 2012年第1期31卷 12-16页

作者： shen, Jun xu, Nan College of Materials Science & Engineering Chongqing University Chongqing 400044 China

The effects of solution and aging treatments on the microstructures and mechanical properties of tungsten inert gas arc welded AZ61 magne-sium alloy joints were investigated by microstructural observations,microhardness tests and tensile *** results showed that the solution treatment led to the β-Mg17Al12 particles dissolved into the α-Mg ***,the microhardness of the fusion zone and the ultimate tensile strength of the welded joints were the *** the increase of the aging temperature,the volume fraction of the β-Mg17Al12 particles in the fusion zone increased and this enhanced the microhardness of the fusion zone ***,the elongation of the welded joints was in-creased slightly with the increase of the volume fraction of the β-Mg17Al12 ***,the ultimate tensile strength of the welded joints increased at first and dropped at 190 ?C due to cracks formed at the boundaries of the β-Mg17Al12 particles.

关键词： magnesium alloy heat treatment microstructure mechanical properties

Effect of preheat on TIG welding of AZ61 magnesium alloy

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第4期19卷 360-363页

作者： dun shen Nan xu College of Material Science ＆ Engineering Chongqing University Chongqing 400044 China

The effects of preheat treatments on the microstructures and mechanical properties of tungsten inert gas （TIG）-welded AZ61 magnesium alloy joints were studied by microstructural observations, microhardness tests and tensile tests. The results showed that the vol- ume fraction of the lamellar β-Mg17（Al,Zn）12 intermetallic compound of in fusion zone （FZ） increased from 15% to 66% with an increase in preheat temperature. Moreover, the microhardness of the FZ and the ultimate tensile strength of the welded joints reached their maximum values when the preheat temperature was 300℃ because more lamellar β-Mg17（Al,Zn）12 intermetallic compounds were distributed at the α-Mg grain boundaries and no cracks and pores formed in the FZ of the welded joint.

关键词： magnesium alloys TIG welding preheating microstructure mechanical properties