检索结果-南通市图书馆

A new pseudorandom number generator based on a complex number chaotic equation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第9期21卷 142-148页

作者：刘杨佟晓筠 school of Computer science and technology Harbin Institute of Technology

In recent years, various chaotic equation based pseudorandom number generators have been proposed. However, the chaotic equations are all defined in the real number field. In this paper, an equation is proposed and proved to be chaotic in the imaginary axis. And a pseudorandom number generator is constructed based on the chaotic equation. The alteration of the definitional domain of the chaotic equation from the real number field to the complex one provides a new approach to the construction of chaotic equations, and a new method to generate pseudorandorn number sequences accordingly. Both theoretical analysis and experimental results show that the sequences generated by the proposed pseudorandom number generator possess many good properties.

关键词： chaotic equation pseudorandom number generator complex number

Oxidation-induced strengthening behavior of reaction formed Al_4SiC_4 ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第S1期26卷 94-98页

作者： HUANG Xiaoxiao1,2),WEN Guangwu1,3),LIU Ruitang2),and ZHENG Xin1)1) school of Materials science and technology,harbin institute of technology,harbin 150001,china 2) school of Material science and Chemical Engineering,harbin Engineering University,harbin 150001,china 3) school of Materials science and technology,harbin institute of technology at weihai,weihai 264209,china harbin Inst Technol Sch Mat Sci & Technol Harbin 150001 Peoples R China harbin Inst Technol Sch Mat Sci & Chem Engn Harbin 150001 Peoples R China harbin Inst Technol Sch Mat Sci & Technol Weihai 264209 Peoples R China

The bending strengths of Al4SiC4 ceramics were investigated from room temperature to 1300 ℃ in air and in vacuum,*** is a novel property that the bending strength increases with increasing test temperatures up to 1300 ℃ in *** strength value of Al4SiC4 ceramics is 449.7 MPa at 1300 ℃ in air,which is about 1.5 times of that at room temperature(300 MPa).The self-healing behavior of the flaws on the specimen surface due to the oxidation of the surface layer of the Al4SiC4 ceramics is considered as the main enhancement mechanism at high temperatures.

关键词： calcination and hot pressing surface strength Al_4SiC_4

Lightweight Si_(3)N_(4)@SiO_(2) ceramic foam for thermal insulation and electromagnetic wave transparency

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第5期17卷 4298-4306页

作者： Zongwei Tong Xiangjie Yan Yuexiang Wang Kexun Li weihai Ma china-Blarus Belt and Road Joint Laboratory on Electromagnetic Environment Effect the 33rd Research Institute of ChinaElectronics Technology Group CorporationTaiyuan 030032China Key Laboratory for Advanced Ceramics and Machining technology of Ministry of Education School of Material Science and EngineeringTianjin UniversityTianjin 300072China Department of Materials science and Engineering Jinzhong UniversityJinzhong 030619China

Increasing porosity is one of the most direct ways to improve the thermal insulation and dielectric properties of *** now,many wet methods for preparing Si_(3)N_(4) ceramic foams usually face the problems of complex rheology,long period,and expensive cost,and the reported pore sizes of Si_(3)N_(4) ceramic foams are typically micron-grade,resulting in a lack of competitiveness in thermal insulation and wave-transparent *** this paper,the Si_(3)N_(4)@SiO_(2) ceramic foams were prepared using an efficient dry-method,which combined three processes of low temperature chemical vapor deposition(LTCVD),template,and isostatic *** method has the advantages of simple operation and short preparation period,and can realize near-net size molding and mass *** addition,the evolution mechanisms of honeycomb microstructure and composition of Si_(3)N_(4)@SiO_(2) ceramic foam during sintering were studied by chemical reaction *** as-prepared Si_(3)N_(4)@SiO_(2) ceramic foam possesses low density(0.377 g·cm^(-3)),high compressive strength(7.5 MPa),low thermal conductivity(0.0808 W·m^(-1)·K^(-1)),and excellent dielectric properties(ε2,tanδ<0.009)in the frequency range of 8-18 GHz,and its maximum working temperature in air can reach up to 1100℃.It will be recommended to be applied in the interlayer of Si_(3)N_(4) ceramic radome to improve its thermal insulation and electromagnetic wave transparency performances.

关键词： silicon nitride ceramic foam honeycomb microstructure dielectric properties thermal insulation

Numerical Simulation and Assessment of Self-induced Tensile Stresses in Steel Ring Restrained Concrete

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

Journal of Wuhan University of technology(Materials science) 2010年第3期25卷 530-533页

作者：马新伟 Department of Civil Engineering Harbin Institute of Technology

For a better understanding of the strains and stresses,numerical simulation was conducted by using ANSYS under the assumption of absolute bond between the steel and *** results show that the stresses and strains in such concrete and steel rings are uneven;the curves of strains and stresses change gradually around the *** ease numerical computation,the mechanical system was simplified under the assumptions of synchronous deformation and uniform strains and *** results of the numerical simulation and simplified stress calculation can match almost *** means that the simplified mechanical model can be used in stress and visco-elastic behavior quantification.

关键词： restrained shrinkage numerical simulation model simplification

Application Analysis of Multiple Neurons Connected with Fast Inhibitory Synapses

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2024年第4期21卷 1905-1918页

作者： Wen Duan weihai Chen Jianhua Wang Zhongcai Pei Jingmeng Liu Jianer Chen school of Automation science and Electrical Engineering Beihang UniversityXueyuan RoadBeijing100191China Hangzhou Innovation institute Beihang UniversityChuanghui StreetHangzhou310051ZhejiangChina school of Electrical Engineering and Automation Anhui UniversityAnhui230601ZhejiangChina Zhejiang Rehabilitation Medical Center Binsheng RoadHangzhou310052ZhejiangChina

Almost all living organisms exhibit autonomic oscillatory activities,which are primarily generated by the rhythmic activities of their neural *** nonlinear oscillator models have been proposed to elucidate these neural behaviors and subsequently applied to the domain of robot ***,the oscillation patterns generated by these models are often unpredictable and need to be obtained through parameter *** study introduces a mathematical model that can be used to analyze multiple neurons connected through fast inhibitory *** characteristic of this oscillator is that its stationary point is stable,but the location of the stationary point changes with the system *** through reasonable topology and threshold parameter selection can the oscillation be *** study analyzed the conditions for stable oscillation in two-neuron networks and three-neuron networks,and obtained the basic rules of the phase relationship of the oscillator network established by this *** addition,this study also introduces synchronization mechanisms into the model to enable it to be synchronized with the sensing ***,this study used these theories to establish a robot single leg joint angle generation *** experimental results showed that the simulated robot could achieve synchronization with human motion,and had better control effects compared to traditional oscillators.

关键词： Oscillator Phase trajectory Synaptic threshold Synchronization Motion generation

Dispersion of multiwalled carbon nanotubes in aluminum powders

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 2009年第2期28卷 175-180页

作者： Deng Chunfeng Zhang Peng Ma Yanxia Zhang Xuexi Wang Dezun Luoyan Ship Mat Res Inst Luoyan 471039 Peoples R China harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China harbin Inst Technol Sch Mat Sci & Engn Weihai 264209 Peoples R China

Multiwalled carbon nanotubes (MWNTs) were treated with the reflux within the concentrated nitric acid for 0-25 h to purify and disperse the tangled MWNTs. The effect of reflux time on the morphology and the weight loss of MWNTs were investigated. Meanwhile,the dispersion of MWNTs with 0-2.0 wt.% in 2024Al powders using mechanical stirring with an assisting ultrasonic shaker in ethanol was also studied. The results show that the reflux time markedly affects the morphology of MWNTs. The weight loss of MWNTs i...

关键词： metal matrix composite powder processing reflux treatment carbon nanotubes (CNTs)

Comment on “Recent progress in thermodynamics of radiation——exergy of radiation,effective temperature of photon and entropy constant of photon”

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第6期52卷 1809-1810页

作者： LIU LinHua school of Energy science and Engineering,harbin institute of technology,harbin 150001,china school of Energy science and Engineering Harbin Institute of Technology

Chen et *** the concepts of effective temperature of photon and entropy constant of photon in a recent paper [Chen Z S,Mo S P,Hu *** progress in thermodynamics of radiation―exergy of radiation,effective temperature of photon and entropy constant of *** china Ser E-Tech Sci,2008,51(8):1096―1109] by enduing a single photon with macroscale thermodynamic parameters such as exergy and *** paper argues that applying these concepts and their inferences to macro-scale thermodynamic system will lead to the results which conflict with macroscale thermodynamic *** means that the concepts of effective temperature of photon and entropy constant of photon are not correct.

关键词： thermodynamics of radiation photon entropy exergy

Design,Simulation and Kinematic Validation of a Hip Prosthetic Mechanism with a Multimotor Function

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2024年第3期21卷 1321-1333页

作者： Majun Song Zhongyi Li Jingjing Jiang weihai Chen Sheng Guo Hao Zheng Lianzheng Niu Hangzhou Innovation institute Beihang UniversityHangzhou310051China Hangzhou Huacheng Software technology Co.Ltd. Hangzhou310051China school of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China

We previously developed a powered hip prosthetic mechanism with kinematic functions of hip flexion-extension and abduction-adduction,and its theoretical and simulation-based kinematics were *** internal-external hip rotation has a positive effect on the movements of human lower limbs according to medical research,we developed a novel hip prosthetic mechanism based on a previous hip prosthesis that possesses motion characteristics similar to those of a human bionic hip,and the motion characteristics of multiple Degrees-of-Freedom(DoFs)were analyzed after kinematic ***,a walking model of the human‒machine model was established,and the walking stability of an amputee,which reflects the rehabilitation effect,was explored while the hip prosthetic mechanism considered the internal-external rotation of the ***,a prototype and its verification platform were built,and kinematic validation of the hip prosthetic mechanism was carried *** results showed that the designed Parallel Mechanism(PM)possesses human-like motion characteristics similar to those of a human bionic hip and can be used as a hip ***,the existing motion characteristic of internal-external hip rotation can enhance the walking stability of an amputee via this hip prosthetic mechanism.

关键词： Hip prosthetic mechanism Parallel mechanism Walking stability Kinematic validation

Relationship between Colored Microstructure under Polarized Light and Shape Recovery Characteristics on the Thermomechanical Cycled CuAlNi Single Crystals

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

Journal of Materials science & technology 2001年第5期17卷 485-489页

作者： Qingfu CHEN, Wei CAi and Liancheng ZHAO school of Materials science and Engineering, harbin institute of technology, harbin 150001, china Dept. of Mater. and Chem. Eng. Liaoning Inst. of Technol. Jinzhou 121001 China

The paper studied the relationship between microstructure and shape recovery characteristics by using colored microstructure analysis under polarized light on the thermomechanical cycled CuAlNi single crystals. The two-way shape memory effect in quenched thin bar resulted from the preferential formation/extinction of martensite variant due to the internal quench stress, and the variant was formed at an angle of about 45 deg. with the tension direction ([001] of the βphase). Initial thermomechanical cycling under relatively low stress single variant stress-induced martensite was formed at an angle of 45 deg. with the tension and its morphology was a lath of parallel twins. More than one group of variants were formed after several training cycles and such variants also caused tilting of some thermally formed accommodated martensite. By overheating the trained sample containing stabilized multi-variants of stress-induced martensite, very coarse martensite structure with a strong asymmetry was produced, which caused the reverse two-way shape memory effect.

关键词： Relationship between Colored Microstructure under Polarized Light and Shape Recovery Characteristics on the Thermomechanical Cycled CuAlNi Single Crystals