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An Analysis of HB-MAP Based on OPNET simulation

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Wuhan University Journal of Natural Sciences 2013年第1期18卷 49-54页

作者： HOU Fangtian YANG Cheng LIU Jianbo ZHANG Yichun TIAN Jiayin ZHANG Yakun School of Information Engineering Communication University of China

HB-MAP （HB-mutual authentication protocol） is a mutual ultra-light-weight authentication protocol we have pro- posed before. In this paper, we present an HB-MAP simulation model. This model is based on the OPNET modeler and includes three parts, namely, the network model, the node model, and the process model. The simulation results are obtained mainly in the aspects of running time, queuing delay, throughput, and channel utilization. To show the performance of HB-MAP, simulation of two other protocols HB and LCAP （load-based concurrent access protocol） is also executed, and comparative analysis is carried out on the results. At the end of the paper, we show a simple process of the attacks and identify that the HB-MAP can defend against some attacks.

关键词： HB-MAP (HB-mutual authentication protocol) OPNET modeler simulation results analytical model

Relative Damage Stress: Dominant Mechanical Factor for the Failure of Soldered Joints under Temperature Cycling

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Journal of Materials Science & Technology 2001年第1期17卷 193-194页

作者： Xin MA Yiyu QIAN and Hongyuan FANG National Key Laboratory of Welding, Harbin institute of TechnologY, Harbin 150001, China F. Yoshida Department of Mechanical Engineering, Hiroshima University, Higashi-Hiroshima 739, Japan Harbin Inst Technol Natl Key Lab Welding Harbin 150001 Peoples R China Hiroshima Univ Dept Mech Engn Higashihiroshima 739 Japan

By temperature normalization of the concept of equivalent damage stress proposed by Lemaitre, a new concept of relative damage stress has been put forward as the dominant mechanical factor for the failure of soldered joints under temperature cycling. Finite element numerical simulation results showed that the highest value of relative damage stress occurred at the high temperature hold time during temperature cycling history.

关键词： Damage Stress damage stress simulation results soldered joints

Effect of Size Polydispersity on Melting of Charged Colloidal Systems

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Chinese Physics Letters 2003年第9期20卷 1626-1629页

作者：陈勇 InstituteofTheoreticalPhysics LanzhouUniversityLanzhou730000

We introduce simple prescriptions of the Yukawa potential to describe the effect of size polydispersity and macroion shielding effect in charged colloidal systems. The solid-liquid phase boundaries were presented with the Lindemann criterion based on molecular dynamics simulations. Compared with the Robbins-Kremer-Grest simulation results, a deviation of melting line is observed at small λ, which means large macroion screening length. This deviation of phase boundary is qualitatively consistent with the simulation result of the nonlinear Poisson-Boltzmann equation with full many-body interactions. It is found that this deviation of the solid-liquid phase behaviour is sensitive to the screening parameter.

关键词： simulation results Deviation PHASE BEHAVIOR Polydispersity electrified SOLID LIQUID meson field theory Phase boundary melting line Melting Molecular Dynamics simulation

Turbulent Fluid Flow and Heat Transfer Calculation in Mold Filling and Solidification Processes of Castings

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Journal of Materials Science & Technology 2001年第1期17卷 69-70页

作者： Geying AN Xun SUN Junqing WANG National Key Laboratory of Precision Hot Processing of Metals Harbin institute of TechnologyHarbin 150001China Shenyang Research institute of Foundry Shenyang 110021China

Based on the time-averaging equations and a modified engineering turbulence model, the mold filling and solidification processes of castings are approximately described. The algorithm for the control equations is briefly introduced, and some problems and improvement methods for the traditional method are also presented. Both calculation and tests proved that. comparing with the laminar fluid flow and heat transfer, the simulation results by using the turbulence model are closer to the real mold filling and solidification processes of castings.

关键词： Solidification Processes Mold Filling solidification processes turbulence model fluid flow and heat transfer mold filling simulation results control equations methods for

Modeling of Heat Transfer and Solidification Process of Spray Formed Billet

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Journal of Materials Science & Technology 2001年第1期17卷 101-102页

作者： Fuyang CAO Chengsong CUI and QingChun LI School of Materials Science and Engineering, Harbin institute of Technology, Harbin 150001, China Harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

In this paper, modeling of heat transfer and solidification process of spray formed billet was established. Thermal profiles of billet at various spray time and under various spray forming conditions were calculated n... 详细信息

关键词： Solidification Process solidification process simulation results spray forming heat transfer

Investigation on Rijke pipe's acoustic characteristics by numerical simulation:modeling the pulsing flow field coupled the inner of pipe with its outer space

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Chinese Journal of Acoustics 2008年第3期27卷 238-249页

作者： ZHONG Yingjie DENG Kai ZHANG Guojun LIN Haihao LI Hua Institute of Energy and Power Engineering Engineering Research Center of Pulse Technology Zhejiang University of Technology Hangzhou 310014

Based on the results of fluid dynamics, heat transfer and acoustics, a Computational Fluid Dynamics （CFD） method was utilized to study the acoustic characteristics and self-excited pulsation mechanism inside a Rijke pipe. To avoid settling the irrational boundary conditions of the finite-amplitude standing wave in the Rijke thermo-acoustic system, the simulation modeling in the flow field, which coupled the inner of pipe with its outer space, was carried out to replace the traditional way in form of internal flow field numerical investigations. A hypothesis for heat source in energy equation including the relationship on unsteady heat of air around heat source, oscillation pressure and oscillation velocity was presented. To reflect the essence of Rijke pipe, simulation on self-excited oscillation was conducted by means of its own pulsation of pressure, velocity and temperature. This method can make the convergence process steady and effectively avoid divergence. The physical phenomenon of the self-excited Rijke pipe was analyzed. Moreover, the mechanisms on the Rijke pipe＇s self-excited oscillation were explained. Based on this method, comparative researches on the acoustic characteristic of the Rijke pipe with different size and different shape of nozzle were performed. The simulation results agreed with the experimental data satisfactorily. The results show that this numerical simulation can be used to study the sound pressure of nozzle for the engineering application of Rijke pipes.

关键词： numerical simulation acoustic characteristics outer space fluid dynamics Computational Fluid Dynamics engineering application heat source internal flow field boundary conditions simulation results experimental data energy equation sound pressure standing wave form of

Fast direction of arrival estimation of wideband sources in unknown correlated noise fields

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Chinese Journal of Acoustics 2006年第2期25卷 184-192页

作者： DAI Zhengjian LIU Yun LI Zhishun College of Marine engineering Northwestern Polytechnical University Xi'an 710072

A computational efficient wideband Direction of Arrival （DOA） estimation method in the presence of unknown correlated noise is presented. A fast Two-sided Correlation Transformation （TCT） focusing matrix that transforms only the signal subspace is developed firstly, and then the propagator method is utilized to compute the focusing matrix and noise correlation matrix. In contrast to conventional wideband DOA estimation method, the proposed method requires only linear operation but does not involve any eigenvelue-decomposition to estimate the focusing matrix; it has a lower computational load, especially when the sensor number is greater than the source number. Because noise correlation matrix is estimated and eliminated from the array correlation matrix, the accuracy of DOA estimation is improved even in the presence of unknown correlation noise. Computer simulation results verified the efficiency of the method.

关键词： noise correlation matrix estimation method DOA estimation simulation results correlation noise linear operation correlated noise signal subspace

Reconstruction and prediction of coherent acoustic field with the combined wave superposition approach

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Chinese Journal of Acoustics 2006年第2期25卷 124-138页

作者： LI Weibing CHEN Jian YU Fei CHEN Xinzhao Institute of sound and vibration research Hefei University of Technology Hefei 230009

The routine wave superposition approach cannot be used in reconstruction and prediction of a coherent acoustic field, because it is impossible to separate the pressures generated by individual sources. According to the superposition theory of the coherent acoustic field , a novel method based on the combined wave superposition approach is developed to reconstruct and predict the coherent acoustic field by building the combined pressure matching matrixes between the hologram surfaces and the sources. The method can reconstruct the acoustic information on surfaces of the individual sources, and it is possible to predict the acoustic field radiated from every source and the total coherent acoustic field can also be calculated spontaneously. The experimental and numerical simulation results show that this method can effectively solve the holographic reconstruction and prediction of the coherent acoustic field and it can also be used as a coherent acoustic field separation technique. The study on this novel method extends the application scope of the acoustic holography technique.

关键词： wave superposition acoustic field holographic reconstruction separation technique acoustic holography simulation results application scope used in

Blind speech source separation via nonlinear time-frequency masking

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Chinese Journal of Acoustics 2008年第3期27卷 203-214页

作者： XU Shun CHEN Shaorong LIU Yulin DSP Lab. Chongqing Communication College Chongqing 400035

Aim at the underdetermined convolutive mixture model, a blind speech source separation method based on nonlinear time-frequency masking was proposed, where the approximate W-disjoint orthogonality （W-DO） property among independent speech signals in time-frequency domain is utilized. In this method, the observation mixture signal from multimicrophones is normalized to be independent of frequency in the time-frequency domain at first, then the dynamic clustering algorithm is adopted to obtain the active source information in each time-frequency slot, a nonlinear function via deflection angle from the cluster center is selected for time-frequency masking, finally the blind separation of mixture speech signals can be achieved by inverse STFT （short-time Fourier transformation）. This method can not only solve the problem of frequency permutation which may be met in most classic frequency-domain blind separation techniques, but also suppress the spatial direction diffusion of the separation matrix. The simulation results demonstrate that the proposed separation method is better than the typical BLUES method, the signal-noise-ratio gain （SNRG） increases 1.58 dB averagely.

关键词： separation method blind separation Fourier transformation clustering algorithm simulation results nonlinear function deflection angle information in cluster center mixture model