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Transition sets of bifurcations of dynamical systems with two statevariables with constraints

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Applied Mathematics and Mechanics(English Edition) 2012年第2期33卷 139-154页

作者：李军陈予恕 School of Astronautics Harbin Institute of TechnologyP.O.Box 137

Bifurcation of periodic solutions widely exists in nonlinear dynamical systems. In this paper, categories of bifurcations of systems with two state variables with different types of constraints are discussed, where some new types of transition sets are added. Additionally, the bifurcation p.o.erties of two-dimensionM systems without constraints are compared with the ones with constraints. The results obtained in this paper can be used by engineers for the choice of the structural parameters of the systems.

关键词： bifurcation constraint singularity theory nonlinear dynamics two statevariables

AERoELASTIC p.o.ERTIES oF SANDWICH BEAM WITH pYRAMIDAL LATTICE CoRE CoNSIDERING GEoMETRIC NoNLINEARITY IN THE SUpERSoNIC AIRFLoW

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Acta Mechanica Solida Sinica 2015年第6期28卷 639-646页

作者： Fengming Li Zhiguang Song Chunchun Sun College of Mechanical Engineering Beijing University of Technology p.o. box 137 School of AstronauticsHarbin Institute of Technology Hong Du Aviation Industry Group

The equation of motion of sandwich beam with pyramidal lattice core in the supersonic flow considering geometric nonlinearity is formulated using Hamilton＇s principle. The piston theory is used to evaluate aerodynamic pressure. The structural aeroelastic p.o.erties are analyzed using frequency- and time-domain methods, and some interesting phenomena are observed. It is noted that the flutter of sandwich beam occurs under the coupling effect of low order modes. The critical flutter aerodynamic pressure of the sandwich beam is higher than that of the isotropic beam with the same weight, length and width. The influence of inclination angle of core truss on flutter characteristic is analyzed.

关键词： sandwich beam pyramidal lattice core geometric nonlinearity aeroelastic flutter supersonic flow

Band Gap p.o.erties of Magnetoelectroelastic Grid Structures with Initial Stress

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Chinese physics Letters 2012年第3期29卷 121-123页

作者： WANG Yi-Ze LI Feng-Ming p.o.box 137 School of AstronauticsHarbin Institute of TechnologyHarbin 150001

The p.o.agation of elastic waves in magnetoelectroelastic grid structures is *** gap p.o.erties are presented and the effects of the magnetoelectroelastic coupling and initial stress are *** calculations are performed using the plane-wave expansion *** results show that the band gap width can be tuned by the initial *** is hoped that our results will be helpful for designing acoustic filters with magnetoelectroelastic materials and grid structures.

关键词： designing magneto initial

VISCoMETRIC STUDY oF poLY(METHYL METHACRYLATE) AND poLYSTYRENE BLENDS IN DIFFERENT SoLVENTS

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Chinese Journal of polymer Science 2003年第1期21卷 15-19页

作者： omar Melad Rajai Baraka Jamil K.J.Salem Hani Hilles Awni El-Khazandar Department of Chemistry AL-Azhar University P.O. Box 1277 GAZA PalestineDepartment of Chemistry AL-Azhar University P.O. Box 1277 GAZA PalestineDepartment of Chemistry AL-Azhar University P.O. Box 1277 GAZA PalestineDepartment of Chemistry AL-Azhar University P.O. Box 1277 GAZA PalestineDepartment of Chemistry AL-Azhar University P.O. Box 1277 GAZA Palestine

The intermolecular interaction between poly(methyl methacrylate) (pMMA) and polystyrene (pS) intetrahydrofuran (THF) and N,N'-dimethyl formamide (DMF) solvents was studied at 28℃ using a dilute solution viscometrymethod. Solvent is believed to play a key role in characterizing the viscosity behavior of the polymer solution. The intrinsicviscosity and viscosity interaction parameter were experimentally measured for the binary (solvent/polymer) and for theternary systems in two solvents. The compatibility of the polymer mixture was discussed in terms of the sign of △b_m. Theresults show that the compatibility of pMMA/pS blend in DMF is larger than that in THF.

关键词： Viscometry Compatibility pMMA/pS blend

The wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply sup.o.ted op.o.ite edges

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Acta Mechanica Sinica 2011年第5期27卷 785-795页

作者： Chun-Chuan Liu Feng-Ming Li Ting-Wei Liang Wen-Hu Huang p. o. box 137 School of AstronauticsHarbin Institute of Technology150001 Harbin China

In this paper,wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply sup.o.ted op.o.ite edges are investigated using the wave *** dynamic responses,active and reactive power flow in the finite plate are calculated by the Mindlin plate theory （MpT） and classic plate theory （CpT）.To satisfy the boundary conditions and continuous conditions at the coupled junction of the finite L-shaped plate,the near-field and far-field waves are entirely contained in the wave *** in-plane longitudinal and shear waves are also *** results indicate that the vibratory power flow based on the MpT is different from that based on the CpT not only at high frequencies but also at low and medium *** influence of the plate thickness on the vibrational power flow is *** the results it is seen that the shear and rotary inertia correction of the MpT can influence the active and reactive power at the junction of the L-shaped plate not only at high frequencies but also at low and medium ***,the effects of structural damping on the active and reactive power flow at the junction are also analyzed.

关键词： Finite L-shaped Mindlin plate Active power flow Reactive power flow Wave app.o.ch

parasitic plant in natural Boswellia papyrifera stands at Humera, Northern Ethiopia

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Journal of Forestry Research 2014年第4期25卷 923-928页

作者： Abraham Yirgu Alemu Gezahgne Habtemariam Kassa Minilik Tsega Forestry Research Centre P.O. BOX 30708 Addis Ababa Ethiopia Centers for International Forestry Research P.O. BOX 5689 Addis Ababa Ethiopia Ethiopian Institute of Agricultural Research P.O. BOX 2003 Addis Ababa Ethiopia

In Boswellia papyrifera （Del.） Hochst natural stands, we stud- ied the association of parasitic plants with B. papyrifera trees from which frankincense was tapped and marketed for domestic and export markets. Data on the rate of infection of parasitic plants on B. papyrifera was collected in three transects located at separate locations around Baha kar, northern Ethiopia. Each transect had ten circular sample p.o.s of 400 m2 and separated by 100 m. Species composition, DBH, height, crown di- ameter, number of main, secondary and tertiary branches and number of parasitic plants on individual trees were recorded. Sixteen tree species were recorded in the combined sample p.o.s. The parasitic plant associ- ated with B. papyrifera was identified as Tapinanthus globiferus. This parasite infected 38% of Boswellia trees in sample p.o.s. The infection rate of the parasitic plant varied from 1 to 33 per Boswellia tree. The infection of T. globiferus on B. papyrifera was predominantly limited to tertiary small branchlets arising from secondary branches; parasitic plants were absent on thick main and secondary branches. In all p.o.s, infectionof T. globiferus was exclusively limited to Boswellia trees. The influence of T. globiferus parasitism on growth of Boswellia trees and its influence on yield of incense p.o.uction needs further investigation. Management of natural stands for frankincense p.o.uction should include measures to reduce infection by T. globiferus.

关键词： Boswellia papyrifera parasitic plant Tapinanthus globiferus Humera Ethiopia

Elastic wave p.o.agation and localization in band gap materials:a review

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Science China(physics,Mechanics & Astronomy) 2012年第10期55卷 1734-1746页

作者： LI FengMing WANG YiZe School of Astronautics Harbin Institute of TechnologyP.O.Box 137Harbin 150001China

Band gap materials(*** crystals) are the artificially periodic structures,which have the stop band characteristic for elastic *** elastic waves will be localized in p.o.onic crystals with defects,which results in the energy being accumulated around the *** a result,it is important to analyze the wave p.o.agation and localization in band gap materials,especially for the structures consisting of smart *** example,with the mechanical-electro and mechanical-electro-magneto coupling,the p.o.onic crystals consisting of piezoelectric and magnetoelectroelastic materials can be applied *** sets the theoretical basis for the design of band gap materials with multi fields *** paper reviews the recent development of the elastic wave p.o.agation and localization in both ordered and disordered band gap *** discussion focuses on the stop band and localization characteristics of elastic *** methods and important results are also ***,some p.o.lems for further studies are *** work aims to present the basic p.o.erties of wave band gaps in p.o.onic crystals and wave localization in disordered periodic structures(*** crystals with definite and random defects and p.o.onic quasicrystals).

关键词： band gap materials stop band characteristics defect localization

Regular Splitting and potential Reduction Method for Solving Quadratic p.o.ramming p.o.lem with box Constraints

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Journal of Computational Mathematics 2002年第6期20卷 643-652页

作者： Zi-Luan Wei(Institute of Computational Mathematics and Scientific / Engineering Computing, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, p.o. box 2719, Beijing, 100080) Institute of Computational Mathematics and Scientific / Engineering Computing Academy of Mathematics and System Sciences Chinese Academy of Sciences P.O. Box 2719 北京 100080

presents a regular splitting and potential reduction method for solving a quadratic p.o.ramming p.o.lem with box constraints. Discussion on the regular splitting and potential reduction algorithm; Complexity analysis ... 详细信息

关键词： quadratic p.o.ramming p.o.lem regular splitting potential reduction algorithm complexity analysis

Study on the Effects of End-bend Cantilevered Stator in a 2-stage Axial Compressor

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Journal of Thermal Science 2009年第2期18卷 119-125页

作者： Songtao WANG Xin DU Zhongqi WANG Harbin Institute of Technology, p.o. box 458, Harbin 150001, China Harbin Institute of Technology P.O. BOX 458 Harbin 150001 China

Leading edge recambering is applied to the cantilevered stator vanes in a 2-stage compressor in this paper. Differentcurving effects are p.o.uced when the end-bend stator vanes are stacked in different ways. Stacking on theleading edge induces a positive curving effect near the *** it is stacked on the centre of gravity, a negativecurving effect takes place. The numerical investigation shows that the flow field is redistributed when theend-bend stators with leading edge stacking are applied. The variations in the stage matching for the mainstreamand near the hub have an impact on the performance of the 2-stage compressor. The isentropic efficiency and thetotal pressure ratio of the compressor are increased near the design condition. The compressor total pressure ratiois decreased near choke and near stall. The maximum flow rate is reduced and the stall margin is decreased.

关键词： axial compressor end-bend blade stacking stage matching