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2008 Vol. 38, No. 2

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FLEXIBLE ELECTRONICS SYSTEM AND THEIR MECHANICALPROPERTIES
2008, 38(2): 137-150. doi: 10.6052/1000-0992-2008-2-J2007-062
Abstract(3710) PDF(1549)
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The novel technology of flexible electronics (also called macroelectronics) is built on flexible and deformable substrates. Due to flexibility and deformability, the technology has found wide applications in many fields. Flexible electronics products have similar structural morphologies and material properties, it is vital to study the mechanical properties of flexible electronics system. This paper presents a state-of-the-art review of the background and technological development of flexible electronics system, and is organized as follows. The concept and applications of flexible electronics system are presented firstly. Then it reviews their basic structures, material properties and manufacture technique, focusing on the mechanical properties of their key structural components, also the future investigations on mechanical properties are briefly recommended at last.
2008, 38(2): 150-252. doi: 10.6052/1000-0992-2008-2-J2008-031
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Advances in structural health monitoring systems in civil engineering
2008, 38(2): 151-166. doi: 10.6052/1000-0992-2008-2-J2007-016
Abstract(3632) PDF(3253)
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The health monitoring of civil engineering structures isan important research field, which covers various areas, suchas data acquisition system, signal processing, structure analysis. In thispaper, the necessity and urgency to implement structural health monitoringin civil engineering are discussed, including the concepts, structures andapplications of the structural health monitoring system. Allsubsystems are analyzed with respect to their functions, characteristics andimplementations. The theories, methods and mechanical issues of thesubsystems are emphasized. Finally, some promising researchsubjects in the area are pinpointed.
DYNAMIC AND ACTIVE CONTROL OF LARGE FLEXIBLE SPACE TRUSS: A REVIEW
2008, 38(2): 167-176. doi: 10.6052/1000-0992-2008-2-J2006-128
Abstract(2656) PDF(1146)
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Large flexiblespace truss (LFST) may be classified according to its applications in spaceindustry. This paper reviews several kinds of LFST (including truss type space station, supporttruss of payload, support truss of mesh reflector antenna, ring tensiontruss, variable geometry truss), their dynamic modeling, active membermodeling, and active control theory and experiment. In the end, some future research topics on dynamic modeling and active control of LFST are pointed out.
RESEARCH PROGRESS OF DEPLOYMENT DYNAMICS OF SPACE INFLATABLE BOOMS
2008, 38(2): 177-189. doi: 10.6052/1000-0992-2008-2-J2007-053
Abstract(2178) PDF(969)
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There have been alarge number of studies recently on space inflatable structures,which can offer extremely low weight, inherent low launch volumeand on-orbit deployment reliability in many large deployablespacecraft applications. Some space programs taking advantages of inflatable structures have been suggested already.However, some important problems must be solved before inflatablestructures can be applied in space environment. One such problemconcerns the control and the deployment dynamics properties of thestructure throughout the inflation and deployment process. Theinflatable boom to deploy and support space structures is a keycomponent of many space inflatable structures. In view of theirimportance, the progress of deployment dynamics of inflatablebooms during the past twenty years is summarized. Several kinds ofinflatable deployment models are discussed, including thenonlinear hinge model, the deployment model of rolled booms, thecontrol volume model, the conservation model of energy andmomentum, and the fluid-structure interaction model. Then, thesimulations using finite element method are discussed. Inflatabledeployment experiments for Z-folded, rolled, polygon andtelescopic conical booms are then reviewed. At the end of thepaper, some attractive topics for further research on thedeployment dynamics of inflatable booms are suggested, includingtheoretical studies, numerical simulations and experimentalstudies.
BRIEF REVIEW ON MODELING METHOD IN STRUCTURAL OPTIMIZATION
2008, 38(2): 190-200. doi: 10.6052/1000-0992-2008-2-J2006-149
Abstract(2399) PDF(1119)
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It is a good choice to establish an optimization model before a structural optimization. Due to the complexity of engineeringproblems, it is very difficult to construct an explicit expression ofstructural response in terms of design variables. Even though anexplicit model may be established for some problems, it would bedifficult to the problem with the model solve.Therefore, an approximation method is needed to establish an optimization modeland convert the model to a solvable one. This paper discusses some frequently used approximate modeling methods and classifies them accordingto modeling ways and methods of sensitivity analysis. The constructingmethods based on sample points, which are widely used in recently years, areintroduced in detail. Then the methods are described in applications andconcrete realization processes for structural optimizations. Advantage,disadvantage and applicable range of each method are analyzed and the trends of model establishing method for structural optimizationsin the future are pointed out.
AN OVERVIEW OF FRICTION MODELS IN MECHANICAL SYSTEMS
2008, 38(2): 201-213. doi: 10.6052/1000-0992-2008-2-J2007-075
Abstract(4094) PDF(1910)
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The friction inmechanical systems plays an increasingly prominent role. It isimportant to reduce friction in mechanical systems, especially the nonlinear friction. Because of its complicated nature, it is very difficult for a single model to account for various mechanisms of friction, and dozens offriction models have been put forward so far. With respect to thedevelopment of the friction modeling in mechanical systems, some important friction phenomena are first described in this paper, suchas Coulomb friction, viscous friction, Stribeck friction,presliding displacement, varying static force and friction lag,etc. Next, a few important friction models in common use are discussed, including six static and seven dynamic friction models. The forms, characteristics andapplicability of these models are discussed in detail. The formsand the parameter identification of the static friction models aresimple and easy, but they cannot be used to simulate the dynamiccharacteristics of friction. Comparatively, the dynamic frictionmodels can describe the friction more completely, with their complicated forms, which makes it difficult to identify related parameters.Then, the influence of friction modeling on the mechanical systemdynamics is briefly discussed as well as the applications offriction models to the control of high precision mechanicalsystems. Lastly, several problems to be further studied arepointed out. This paper provides some guidance in the selection of friction models in applications.
A REVIEW ON INVESTIGATIONS OF WING ROCK PROBLEMS UNDER HIGH ANGLES OF ATTACK
2008, 38(2): 214-228. doi: 10.6052/1000-0992-2008-2-J2007-029
Abstract(2678) PDF(1106)
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Wing rock, as a typical problem ofdynamic characteristics under high angle of attack, is one ofthe phenomena of lateral-directional instability that are often encounteredin the design of modern fighters and missiles. In the recent twenty years,wing rock problems have been attracted much attention inaviation-industry and research institutions. Many papers on experiment and calculation method have been published on this problem and great progress has been made. In this paper, the researches of wing rock in experiment and calculation are summarized by referencing more than 100 articles on this problem and the furtherresearch directions on wing rock are suggested.
CHARACTERS OF MICRO-STRUCTURE AND PERCOLATION IN TIGHT SANDSTONE GAS RESERVOIRS
2008, 38(2): 229-236. doi: 10.6052/1000-0992-2008-2-J2007-014
Abstract(2734) PDF(1037)
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With the dwindling ofconventional gas reservoirs, people are paying attention to theexploration and exploitation of tight sandstone gas reservoirs.However, few studies were directed to the mechanism of hightransfer fluid; the exploitation has been very limited. Tightsandstone gas reservoirs are characterized by extended spatialscales, including micro scale, natural fracture scale, andhydraulic fracture scale, and there will be multi-scale effects while gas is percolated through the tight sandstone. Gas transfer processesin the tight sandstone gas reservoirs consist of desorption,diffusion and percolation, including diffusion in theconcentration field and percolation in the pressure field. Thereview of this paper discusses the special characters of tightsandstone gas reservoirs, the descriptions and methodology. The range of gas transfer in tight sandstone is classified on the basisof Knudsen number. It is concluded that some fine descriptive methods should be established to describe tight sandstonemicro-structures and the study about tight sandstone gas transferin the condition of multi-scales should be carried out.
MICRO- AND NANOPARTICLES VIA CAPILLARY FLOWS
2008, 38(2): 237-246. doi: 10.6052/1000-0992-2008-2-J2008-017
Abstract(2076) PDF(737)
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This review surveyssome capillary flows capable of stretching fluid interfaces downto the micrometric dimension and below. These types of flows havebecome the basis for attractive techniques to produce monodispersemicro- and nanoparticles with either simple or core-shellstructure (micro- and nanocapsules, coaxial nanofibers, and hollownanofibers). These techniques enable precise control on theparticle mean size. We also review the basic physics of the flowand the dimensionless parameters that govern these capillaryflows. Some examples of the types of particles produced by a fewdevices are also presented.
A BRIEF INTRODUCTION OF FINISHED KEY PROJECTS OF 2007 IN
2008, 38(2): 247-249. doi: 10.6052/1000-0992-2008-2-J2008-030
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2008, 38(2): 253-355. doi: 10.6052/1000-0992-2008-2-J2008-040
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2008, 38(2): 256-258. doi: 10.6052/1000-0992-2008-2-J2008-038
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2008, 38(2): 259-260. doi: 10.6052/1000-0992-2008-2-J2007-159
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2008, 38(2): 261-262. doi: 10.6052/1000-0992-2008-2-J2008-024
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2008, 38(2): 263-264. doi: 10.6052/1000-0992-2008-2-J2008-023
Abstract(1493) PDF(822)
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