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Mesh theory of angle modified dual tori double-enveloping toroidal worm drive

Science China(Technological Sciences) 2010年第7期53卷 1913-1927页

作者： ZHAO YaPing1, SU DaiZhong2, ZHANG Zhao1, WEI WenJun3.& DONG XueZhu3.1 college of Machinery and Automation, wuhan university of Science and{3., wuhan 43.081, China 2 Advanced Design and Manufacturing engineering Center, Nottingham Trent university, Nottingham NG1 4BU, UK 3.college of engineering, China Agricultural university, Beijing 100083. China college of Machinery and Automation Wuhan University of Science and Technology Wuhan China Advanced Design and Manufacturing engineering Center Nottingham Trent University Nottingham UK college of engineering China Agricultural University Beijing China

In this paper, the meshing theory of the angle modified hourglass worm drive is enriched and developed. The ordinary condition of the angle modification is derived and the physical significance of the modification is interpreted. A normal section methodology is proposed for meshing analysis, which can be used to compute the normal distance near a singular meshing point of a conjugate surface couple. By means of the method and after analyzing the normal transversals, it is specified that the worm helicoid, the nominal former contact zone and the new contact zone intersect each other along the locus of singular points of the instantaneous contact lines of an angle-modified worm pair. As a result, it is explained clearly that those three osculate each other but the osculations are different in degree. Moreover, the mechanism of removing the twice-contacted zone from the worm gear tooth surface is clarified and the reason of shortening the worm working length is also elucidated. With the help of the theory described in the present paper and the thorough and systematic research on the relevant meshing characteristics, the angle modified dual tori double-enveloping toroidal worm drive has been shown to be an excellent new-fashioned hourglass worm set.

关键词： hourglass worm angle modification double-enveloping osculation normal transversal

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METHOD TO SOLVE ELASTIC CONJUGATE SURFACES IN MULTI-TEETH MESHING

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Chinese Journal of mechanical engineering 2002年第4期15卷 348-352页

作者： Yi ChuanyunSchool of mechanical Science and engineering, Huazhong university of Science and{3.,wuhan 43.074, China School of mechanical Science and engineering Huazhong University of Science and Technology Wuhan 430074

A method to solve the elastic conjugate surfaces in multi-teeth meshing ispresented. In mechanical manufacturing and design, there exist a lot of problems relating toconjugate surfaces, such as three-dimensional engagement, steel rolling and workpiece machining,which cause great effects on the quality of machining and performances of transmission. This methoddescribes relation between conjugate motion and elastic deformation in the process of mesh-in andmesh-out, and can be used to determine the profile of gear tooth by a certain given load sharing.

关键词： multi-teeth meshing elastic conjugate surfaces

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NOVEL FORMULATION OF STATIC STABILITY FOR A WALKING QUADRUPED ROBOT

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Chinese Journal of mechanical engineering 2003年第2期16卷 120-122页

作者： Chen XuedongSchool of mechanical Scienceand engineering,Huazhong university of Scienceand{3.,wuhan 43.074, China School of mechanical Science and engineering Huazhong University of Science and Technology Wuhan 430074

By defining the static stable area for foot placement, a new approach toanalysis of quadruped robot stability is presented. Unlike conventionally, the method avoids solvingcomplicated direct kinematics of quadruped robot and shows the information on the robot stabilityand the selection of swing leg. Especially, the proposed algorithm can be used as real-timeoperation for on-line gait generation and control for quadruped robots. The effectiveness of theproposed approach is shown through a practical crawling experiment of the quadruped robotTITAN-VIII.

关键词： quadruped robot static stability gait generation

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A New Secure Password Authentication Scheme Using Smart Cards

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wuhan university Journal of Natural Sciences 2008年第6期13卷 739-743页

作者： WANG Bangju1,2, WANG Yuhua3. ZHANG Huanguo1 1. School of Computer, wuhan university/Key Laboratory of Aerospace Information Security and Trust Computing of Ministry of Education, wuhan 43.072,{3., China 2. School of Science, Huazhong Agricultural university, wuhan 43.070,{3., China 3. college of Information Science and engineering, Henan university of technology Zhengzhou 450001, Henan, China School of Computer Wuhan University/Key Laboratory of Aerospace Information Security and Trust Computing of Ministry of Education Wuhan China School of Science Huazhong Agricultural University Wuhan China college of Information Science and engineering Henan University of Technology Zhengzhou China

Thirteen security requirements for an ideal password authentication scheme using smart cards are listed and a new smart card based password authentication scheme with identity anonymity is proposed. The new scheme can satisfy all the listed ideal security requirements and has the following merits：（1） it can resist all the attacks listed in introduction; （2） less storage memory requirement due to no verification table stored in server; （3. low computational cost due to hash functions based operations; （4） even if the smart card is lost, the new system is still secure; （5） As user identity is anonymous, this scheme is more practical. The new proposed scheme can be applied in source constraint networks.

关键词： password password authentication hash function attack smart card

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Finite Element Analysis of Die Geometry and Process Conditions Effects on Equal Channel Angular Extrusion for β-Titanium Alloy

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Journal of Iron and Steel Research International 2012年第10期19卷 54-58页

作者： SI Jia-yong1,2, GAO Fan3. ZHANG Ji3.(1. State Key Laboratory of Powder Metallurgy, Central South university, Changsha 410083. Hunan, China 2. college of mechanical and Electrical{3., Central South university of Forestry and technology, Changsha 410004, Hunan, China 3. High Temperature Material Research Division, Central Iron and Steel Research Institute, Beijing 100081, China) State Key Laboratory of Powder Metallurgy Central South University Changsha Hunan China college of mechanical and Electrical engineering Central South University of Forestry and Technology Changsha Hunan China High Temperature Material Research Division Central Iron and Steel Research Institute Beijing China

The finite element analysis was applied to evaluate the respective influences of die geometry and process conditions on plastic strain distribution for β-titanium (Ti-13.11Cr3.l) alloy during the equal channel angular extrusion (ECAE). It was found that optimum equal channel angular extrusion die geometry is strongly material dependent. Optimal strain homogeneity in the Ti-13.11Cr3.l alloy may be achieved at r (inner radius)=5 mm, R (outer radius)=3.mm. The equivalent plastic strain increases with increasing friction coefficient. And the better homogeneity of the equivalent plastic strain distribution can be achieved when friction coefficient value is lower. The faster the ram speed is, the lower the homogeneity of the equivalent plastic strain distribution is and the influence is slight. The back-pressure does not help to improve the plastic strain homogeneity, and the increasing temperature has a slightly favourable effect on the plastic strain homogeneity between 400 and 600 ℃.

关键词： equal channel angular extrusion finite element analysis die geometry β-titanium

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The Vibration Controllability of 20~# Steel Pipe Excited by Unsteady Flow

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Journal of wuhan university of technology(Materials Science) 2011年第6期26卷 1222-1226页

作者：寇子明 college of mechanical engineering Taiyuan University of Technology Shanxi Province Mine Fluid Control engineering Research Center

An excited experiment system of 20# steel pipe was established with oil cylinder, 20# steel pipe, frequency converter, pump station and wave exciter generating unsteady flow artificially. The experimental results showed that the 20# steel pipe could vibrate with the excitation of unsteady flows, and the vibration was periodic, instead of a harmonic one. Particles on the front and rear positions of pipe vibrated synchronously, and the vibration intensity of the pipe＇s two ends was greater than in the middle. System pressure and wave exciter＇s frequency had much influence upon pipe＇s amplitude. Pipe＇s vibration frequency was little affected by system pressure, and its value was close to the wave exciter＇s. Therefore, the active control of pipe＇s vibration can be realized by setting system pressure and adjusting frequency converter＇s frequency.

关键词： unsteady flow steel pipe vibration control wave exciter

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Detection of bursts in neuronal spike trains by the mean inter-spike interval method

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Progress in Natural Science:Materials International 2009年第2期19卷 229-235页

作者： Lin Chena,b,Yong Deng c,Weihua Luo a,Zhen Wang a,Shaoqun Zenga,a hubei Bioinformatics and Molecular Imaging Key Laboratory,Huazhong university of Science and technology,{3. 43.074,China b college of mechanical engineering,Guangxi university,Nanning,53.004,China c college of Optoelectronic Science of engineering,Huazhong university of Science and technology,{3. 43.074,China hubei Bioinformatics and Molecular Imaging Key Laboratory Huazhong University of Science and Technology Wuhan 430074 China college of mechanical engineering Guangxi University Nanning 530004 China college of Optoelectronic Science of engineering Huazhong University of Science and Technology Wuhan 430074 China

Bursts are electrical spikes firing with a high frequency,which are the most important property in synaptic plasticity and information processing in the central nervous system. However,bursts are difficult to identify because bursting activities or patterns vary with phys-iological conditions or external stimuli. In this paper,a simple method automatically to detect bursts in spike trains is described. This method auto-adaptively sets a parameter (mean inter-spike interval) according to intrinsic properties of the detected burst spike trains,without any arbitrary choices or any operator judgment. When the mean value of several successive inter-spike intervals is not larger than the parameter,a burst is identified. By this method,bursts can be automatically extracted from different bursting patterns of cultured neurons on multi-electrode arrays,as accurately as by visual inspection. Furthermore,significant changes of burst variables caused by electrical stimulus have been found in spontaneous activity of neuronal network. These suggest that the mean inter-spike interval method is robust for detecting changes in burst patterns and characteristics induced by environmental alterations.

关键词： Inter-spike interval Bursts Spike trains Multi-electrode arrays

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Effect of Addition of Sodium Dodecyl Sulfite on Physical Properties of Wheat Gluten Films

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Journal of wuhan university of technology(Materials Science) 2005年第2期20卷 15-19页

作者：曾瑜薇 School of Foreign Language Hubei University of TechnologyWuhan 430068China Assoc.Prof

Films were made from the wheat glutens treated with 5%,10%,15%,20%,25% and 3.%(wt% of gluten) of sodium dodecyl sulfite (SDS) in order to improve the properties of the films. Glycerol was used as a *** addition of SDS in wheat glutens prior to forming films significantly increased the elongation at break(E) (Pmechanical properties of wheat gluten *** obivous improvement in water vapor permeability and extensibility of gluten films means that the use of SDS is a potential choice for improving properties of gluten films. The edible film was used to preserve tomatoes. The experimental results show that the shelf life of tomatoes coated with the edible film is extended, and the nutritional quality is kept well.

关键词： wheat gluten sodium dodecyl sulfite (SDS) tensile strength (TS) elongation at break(E) water vapor permeability(WVP) tomato preservation

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Parameter identification theory of a complex model based on global optimization method

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Science China(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2 & XU BingYe3.1 college of Automotive engineering, South China university of{3., Guangzhou 510640, China 2 Beijing Research Institute of mechanical and Electrical{3., Beijing 100083. China 3.Department of engineering Mechanics, Tsinghua university, Beijing 100084, China college of Automotive engineering South China University of Technology Guangzhou China Beijing Research Institute of mechanical and Electrical technology Beijing China Department of engineering Mechanics Tsinghua University Beijing China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 927°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization

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Mechanism of Breakdown in Laminar-Turbulent Transition of Incompressible Boundary Layer on a Flat Plate

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Transactions of Tianjin university 2007年第2期13卷 79-87页

作者：唐洪涛罗纪生周恒 School of mechanical engineering Tianjin University

Temporal mode direct numerical simulation was done for the process of laminar-turbulent transition in an incompressible boundary layer on a flat plate. The analysis of the results showed that during the breakdown process of laminar-turbulent transition, the modification of the mean flow profile by the disturbances led to a remarkable change in its stability characteristics, manifested in the significant enlargement of the linear unstable zone and the maximum amplification rate, and led to that many more disturbances were excited and enhanced rapidly, correspondingly the turbulent energy also increased rapidly, and the mean flow profiles evolved swiftly from laminar to turbulent. It was also found that if the oblique waves in the initial disturbances did not form symmetrical pairs, the subsequent span-wise mean velocities would, in general, be nonzero due to nonlinear interaction, which would have a great effect on the stability characteristics and also implied that the turbulence obtained by direct numerical simulation might not be fully a random process.

关键词： boundary layer transition direct numerical simulation breakdown

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