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World Journal of Engineering and Technology 2021年第1期9卷 15-25页

作者： Brice Poumegne Kouam Didier Fokwa Dieunedort Ndapeu Médard Fogue Research unit of Mechanics and Physical Systems Modeling of (UR2MSP) Department of Physics Faculty of Science Uni-versity of Dschang Dschang Cameroon Research unit of Engineering of Industrial Systems and Environment (URISIE) IUT/FV Bandjoun Department of Physics Faculty of Science University of Dschang Dschang Cameroon Laboratory of Mechanics (LM) Department of Civil Engineering Advanced Teacher’s Training College for Technical Educa-tion University of Douala Douala Cameroon Laboratory of Mechanics and Appropriate Materials (LAMMA) Department of Civil Engineering Advanced Teacher’s Training College for Technical Education University of Douala Douala Cameroon

The bamboo stem, when mature 5 to 6 years, serves as a building material for modest houses and its marrow as packaging purposes. One of the strains related to the uses of bamboo stem is most often the compression towards the axial direction. The phenomenon of damage is very often observed during such loading. The present study on raffia aims to analyze this phenomenon through cyclical stresses as usual. From the results obtained, it was observed in the stress-strain plane, that the area of the hysteresis loops and the residual strain evolve with two parameters: the number of cycles and the stress peaks. The study of energy dissipation has shown that it evolves according to an exponential law as a function of the number of cycles. The distribution of the energy rate along a stem shows that the samples from the zone close to the base store twice (0.0412 MJ/m3) more energy than the samples taken from the top of the foliage (0.019 MJ/m3).

关键词： Bamboo Raphia Cyclic Compression Energy Dissipation

Vibrational behavior of isotropic plate structures in contact with a bounded fluid via unified formulation

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Chinese Journal of Aeronautics 2019年第4期32卷 921-937页

作者： F.G.CANALES J.L.MANTARI Faculty of Mechanical Engineering Instituto de Investigación en Ingeniería Naval(IDIIN)Universidad Nacional de Ingenieria(UNI) Department of Mechanical Engineering University of New Mexico

This paper presents an analytical solution for free vibration analysis of thick rectangular isotropic plates coupled with a bounded fluid for various boundary conditions. In order to consider displacement theories of an arbitrary order, the Carrera unified Formulation(CUF) is used. The eigenvalue problem is obtained by using the energy functional, considering plate and fluid kinetic energies as well as the potential energy of the plate. The Ritz method is used to evaluate the displacement variables, and the functions used in the Ritz series can be adjusted to consider any of the classical boundary conditions. The convergence of the solution is analyzed, and a validation of results considering open literature and 3D finite element software is performed. Parametric studies are carried out to obtain natural frequencies as a function of the side-to-thickness ratio, plate aspect ratio, fluid domain size, plate boundary conditions, and fluid-solid density ratio. Pressure and velocity in the fluid domain are evaluated in order to establish the consistency of the *** results for thick plates are obtained with a much lower computational cost compared to that of 3D finite element solutions.

关键词： Added mass Fluid-structure interaction Plate Ritz method unified formulation Vibration

Optimization of Approximate Solution of Integral Equations of Several Variables

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Acta Mathematica Sinica,English Series 2002年第3期18卷 455-462页

作者： Wan MA Xing Hua WANG Department of Mathematics, Zhejiang university. Hangzhou 310028, P. R. China atho.imed.uni-erlangen.de

In this paper, we consider the problem of optimization of adaptive direct methods of operator equations. Adaptivity of a direct method is understood in the sense that the subspace on the basis of which it is constructed is chosen depending on the operator of the concrete equation (otherwise, nonadaptive direct method is then concerned), which would essentially let us increase the precision. For some classes of the second kind of Fredhlom integral equations with anisotropic smooth kernels we determine the exact order of the error of adaptive direct methods, and we also give an optimal algorithm.

关键词： Integral equations Direct methods Anisotropic Sobolev classes

The Effect of Non-equilibrium Condensation on the Drag Coefficient in a Transonic Airfoil Flow

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Journal of Thermal Science 2012年第6期21卷 518-524页

作者： I.W.Kim M.M.A.Alam S.J.Lee Y.D.Kwon S.B.Kwon School of Mechanical Engineering Kyungpook Nat.Uni.1370Sankyuk-dongDaegu 702-701Korea Dept.of Advanced & Control Eng.Saga uni.Japan

In this study, a transonic flow past NACA0012 profile at angle of attack α=0^0 whose aspect ratio AR is 1.0 with non-equilibrium condensation is analyzed by numerical analysis using a TVD scheme and is investigated using an intermittent indraft type supersonic wind tunnel. Transonic flows of 0.78-0.90 in free stream Mach number with the variations of the stagnation relative humidity（φ0） are tested. For the same free stream Mach number, the increase in φ0 causes decrease in the drag coefficient of profile which is composed of the drag components of form, viscous and wave. In the case of the same Moo and To, for more than φ0=30%, despite the irreversibility of process in non-equilibrium condensation, the drag by shock wave decreases considerably with the increase of φ0. On the other hand, it shows that the effect of condensation on the drag coefficients of form and viscous is negligible. As an example, the decreasing rate in the drag coefficient of profile caused by the influence of non-equilibrium condensation for the case of M∞=0.9 and φ0 =50% amounts to 34%. Also, it were turned out that the size of supersonic bubble （that is, the maximum height of supersonic zone） and the deviation of pressure coefficient from the value for M=1 decrease with the increase of φ0 for the same M∞.

关键词： Non-equilibrium condensation Transonic Moist air Drag coefficient Pressure coefficient

Design of Multivalued Circuits Based on an Algebra for Current-Mode CMOS Multivalued Circuits

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Journal of Computer Science & Technology 1995年第6期10卷 564-568页

作者：陈偕雄 ClaudioMoraga DepartmentofElectronicEngineering UniversityofHangzhouHangzhou310028 DepartmentofComputerScience Uni

An algebra proposed for current-mode CMOS multivalued circuits is briefly reviewed. This paper discusses its application in the design of multivalued circults. Several current-mode CMOS quaternary and quinary circuits are de-signed by algebraic means. The design method based on this algebra may offer a design simpler than the previously knowll ones.

关键词： Multiple-valued logic logic design current mode CMOS circuits

Optimal Investment Problem for an Insurer and a Reinsurer

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Journal of Systems Science & Complexity 2015年第6期28卷 1326-1343页

作者： LI Danping RONG Ximin ZHAO Hui School of Science Tianjin University Center for Applied Mathematics Tianjin Uni-versity

This paper studies the optimal investment problem for an insurer and a reinsurer. The basic claim process is assumed to follow a Brownian motion with drift and the insurer can purchase proportional reinsurance from the reinsurer. The insurer and the reinsurer are allowed to invest in a risk-free asset and a risky asset. Moreover, the authors consider the correlation between the claim process and the price process of the risky asset. The authors first study the optimization problem of maximizing the expected exponential utility of terminal wealth for the insurer. Then with the optimal reinsurance strategy chosen by the insurer, the authors consider two optimization problems for the reinsurer： The problem of maximizing the expected exponential utility of terminal wealth and the problem of minimizing the ruin probability. By solving the corresponding Hamilton-Jacobi-Bellman equations, the authors derive the optimal reinsurance and investment strategies, explicitly. Finally, the authors illustrate the equality of the reinsurer＇s optimal investment strategies under the two cases.

关键词： Hamilton-Jacobi-Bellman equation optimal reinsurance and investment strategies proportional reinsurance ruin probability utility maximization

Polymer grafting modification of the surface of nano silicon dioxide

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Journal of university of Science and Technology Beijing 2002年第6期9卷 426-430页

作者： WeiWu ShouciLu 等 ResearchCenteroftheMinistryofEducationforHighGravityofEngineering＆Technology BeijingUniversityofChemicalTechnologyBeijing100029China CivilandEnvironmentalEngineeringSchool Uni

Based on the composite modification technology of the surface of nano Silicondioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on thesurface of nano silicon dioxide. The modification mechanism and the bonding status on the surface ofnano silicon dioxide after modification were suggested via the results of the infrared spectrum,transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formedby hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxideto form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto thesurface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer throughfree radical polymerization between the double bonds on the surface of nano silicon dioxide andstyrene under the action of initiating agent. The dispersibility of nano silicon dioxide and thecontrollability of surface modification of nano silicon dioxide can be greatly improved by themodification process.

关键词： nano silicon dioxide grafting modification mechanism silane couplingagent styrene

Declining diagnostic accuracy of non-invasive fibrosis tests is associated with elevated alanine aminotransferase in chronic hepatitis B

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World Journal of Clinical Cases 2018年第12期6卷 521-530页

作者： Lin Wang Yao-Xin Fan Xiao-Guang Dou Department of Infectious Diseases Shengjing Hospital of China Medical Uni-versity

AIM To explore the effect of alanine aminotransferase(ALT) on the performance of non-invasive fibrosis tests in chronic hepatitis B(CHB) patients. METHODS A total of 599 treatment-naive and biopsy-proven CHB patients were included in the study. The cohort was divided into the following three groups: Normal ALT(ALT ≤ 40), slightly elevated ALT(40 80). The diagnostic performance of five common non-invasive fibrosis tests for liver fibrosis(stages S2-4), including the aspartate aminotransferase(AST)-to-platelet(PLT) ratio index(APRI), fibrosis index based on 4 factors(FIB-4), King's score, Forns index and gamma-glutamyl transpeptidase(GGT)-to-PLT ratio(GPR), were evaluated for each group. RESULTS Higher ALT levels were associated with higher non-invasive fibrosis test scores. Patients with the same fibrosis stage but higher ALT levels showed higher noninvasive test scores. The areas under the receiver operating characteristics curves(AUROCs) of the noninvasive tests for prediction of ≥ S2 were higher for patients with ALT ≤ 40 U/L(range 0.705-0.755) and 40 80 U/L(range 0.604-0.701). The AUROCs for predicting ≥ S3 and S4 were higher in patients with ALT ≤ 40 U/L(range 0.736-0.814 for ≥ S3, 0.79-0.833 for S4) than in patients with 40 80 U/L(range 0.7-0.784 for ≥ S3, range 0.662-0.719 for S4). The diagnostic accuracy of the non-invasive tests decreased in a stepwise manner with the increase in *** ALT has a significant effect on the diagnostic performance of non-invasive fibrosis tests. The ALT level should be considered before performing these noninvasive tests.

关键词： Chronic hepatitis B Non-invasive tests Liver fibrosis Alanine aminotransferase Inflammation

Second harmonic 423-nm laser generated by BIBO crystal for calcium optical frequency standard

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Chinese Optics Letters 2008年第5期6卷 317-319页

作者：陈振辉鹿博徐志学庄伟于闯于得水黄凯凯陈徐宗陈景标 School of Electronics Engineering and Computer Science Peking University Beijing uni-Quanta Co.Ltd

Calcium is one prospective element for the modern optical frequency standard. The 423-nm transition line of calcium atoms has been widely used in laser slowing and laser cooling, the precise spectrum measurement, and the magnetic optical trapping （MOT）. However, there is no any available commercial diode laser working at this wavelength. We built a 423-nm laser based on extra bow-tie cavity and by using a Brewstercut uncoated BIBO （BiB306） crystal, which worked at room temperature, with conversion efficiency of 3.75%, and a potential up to 20%.

关键词： Atomic spectroscopy Calcium Cooling Frequency standards Laser cooling Natural frequencies Optical materials

Simulation of the Effects of Several Factors on Arc Plasma Behavior in Low Voltage Circuit Breaker

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Plasma Science and Technology 2005年第5期7卷 3069-3072页

作者：李兴文陈德桂汪倩李志鹏 State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong Uni-versity

Taking into account the properties of the arc plasma and the electromagnetic, heat and radiative phenomena, commercial computational fluid dynamics software PHOENICS has been adapted and modified to develop the three-dimensional magneto-hydrodynamic （MHD） model of arc in a low voltage circuit breaker. The effects of the arc ignition location, venting size and gassing material on arc behavior have been investigated. The analysis of the results show that the arc velocity accelerates with the increase in the distance between arc ignition location and of the venting size, and the existence of the gassing material is beneficial to improving the arc voltage and reducing the arc temperature.

关键词： arc model venting gassing material