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International Symposium on Electronic Materials and Packaging

作者： Guo-wei Xiao P.C.H. Chan A. Teng Jian Cai M.M.F. Yuen Department of Electrical and Electronic Engineering Hong Kong University of Science and Technology Hong Kong China Computer Aided Design & Manufacturing Facility Hong Kong University of Science and Technology Hong Kong China Department of Mechanical Engineering Hong Kong University of Science and Technology Hong Kong China

ISBN: (纸本)0780366549

The electroplating-based flip chip process has many advantages over other solder bumping methods, where the bump fabrication process can affect the reliability of solder joints. In this paper, the effect of the UBM and electroplating process of the solder bump on the shear strength of the solder bump is studied, as well as the relationship between the shear test failure mode and solder bump fabrication process. It is reported that the Cu surface roughness is affected by the Cu plating current density and the appropriate current density is in a range from 10/spl sim/40 mA/cm/sup 2/. The solder bump plating process temperature should be within 30-35/spl deg/C. It is observed that the growth kinetics of intermetallic compound formation are affected by the Cu stud structure. The ratio of Cu/sub 3/Sn to the total Cu-Sn IMC layer thickness was from 0.5 to 0.15 with various Cu microstructures at 150/spl deg/C during thermal aging tests. The activation energy was in the range of 0.78 eV to 1.14 eV. Five shear test failure modes are analyzed which are related to the electroplating process.

关键词： Testing Fabrication Current density Flip chip Soldering Rough surfaces Surface roughness Temperature Kinetic theory Intermetallic

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Reliability-based design sensitivity analysis and optimization for the hyper-elastic structure using the meshfree method

American Society of Mechanical Engineers, Pressure Vessels a...

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American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP 2000年 400卷 107-114页

作者： Park, Young H. Kim, Nam H. Yim, Hong J. Department of Mechanical Engineering New Mexico State University Las Cruces NM 88003-8001 United States Center for Computer-Aided Design University of Iowa Iowa City IA 52242-1000 United States Sch. of Mech. and Automot. Eng. Kookmin University Seoul Korea Republic of

In this paper, efficient design sensitivity analysis (DSA) and optimization methods are presented to support reliability-based design for a hyper-elastic structure with frictional contact using a meshfree method. For the structural reliability analysis, the first-order reliability method (FORM) is utilized. The continuum-based DSA method is employed to search the most probable point (MPP) in the standard normal random variable space for structural reliability analysis. To develop the continuum-based DSA for the hyper-elastic constitutive relation and penalized contact formulation, the material derivative of continuum mechanics is utilized. The sensitivity equation is solved at each converged load step using the same tangent stiffness of response analysis due to the path dependency of the frictional contact problem. For the reliability-based structural DSA and optimization method, analytical reliability-based DSA is used to calculate the design sensitivity of reliability indices with respect to probabilistic design variables. A numerical result is presented to validate the proposed method.

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A stabilized conforming nodal integration for Galerkin mesh-free methods

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International Journal for Numerical Methods in engineering 2000年第2期50卷

作者： Jiun-Shyan Chen Cheng-Tang Wu Sangpil Yoon Yang You The Department of Mechanical Engineering and Center for Computer-Aided Design The University of Iowa 2137 SC Iowa City IA 52242-1527 U.S.A. Associate Professor Postdoctoral Fellow Graduate student

Domain integration by Gauss quadrature in the Galerkin mesh-free methods adds considerable complexity to solution procedures. Direct nodal integration, on the other hand, leads to a numerical instability due to under integration and vanishing derivatives of shape functions at the nodes. A strain smoothing stabilization for nodal integration is proposed to eliminate spatial instability in nodal integration. For convergence, an integration constraint (IC) is introduced as a necessary condition for a linear exactness in the mesh-free Galerkin approximation. The gradient matrix of strain smoothing is shown to satisfy IC using a divergence theorem. No numerical control parameter is involved in the proposed strain smoothing stabilization. The numerical results show that the accuracy and convergent rates in the mesh-free method with a direct nodal integration are improved considerably by the proposed stabilized conforming nodal integration method. It is also demonstrated that the Gauss integration method fails to meet IC in mesh-free discretization. For this reason the proposed method provides even better accuracy than Gauss integration for Galerkin mesh-free method as presented in several numerical examples. Copyright © 2001 John Wiley & Sons, Ltd.

关键词： mesh-free element-free Galerkin reproducing kernel nodal integration stabilization

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The nonlinear behaviour of a pantograph current collector suspension

The nonlinear behaviour of a pantograph current collector su...

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ASME 1999 design engineering Technical Conferences, DETC 1999

作者： Drugge, L. Larsson, T. Berghuvud, A. Stensson, A. Division of Computer Aided Design Department of Mechanical Engineering Luleå University of Technology LuleåSE-971 87 Sweden

ISBN: (纸本)9780791819777

The pantograph-catenary system is a critical component for trains required to run at higher speeds. The pantograph often includes nonlinear characteristics and the scope of this work is to investigate if nonlinear dynamic phenomena can occur in an existing design. A model of a pantograph suspension subsystem has been developed according to physical parameter values of the head suspension of the Schunk WBL88/X2 pantograph, providing electric power to the Swedish high-speed train X2. Studies of the system response for different force excitation show both harmonic, subharmonic and chaotic behaviour for the investigated parameter regions. Copyright © 1999 by ASME

关键词： Railroads

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Braille printer dynamics

Braille printer dynamics

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ASME 1999 design engineering Technical Conferences, DETC 1999

作者： Jerrelind, J. Stensson, A. Division of Computer Aided Design Department of Mechanical Engineering Luleà University of Technology LuleàSE-971 87 Sweden

ISBN: (纸本)9780791819777

A Braille printer forms dots in paper, which are read by blind people. The dots are produced by hammers, which basically consist of a spring loaded moving core that is excited by electromagnetic forces. The system is characterised by nonlinear properties such as electromagnetic forcing and impacts. Problems with quality, high temperature and noise limit the operating speed of the printer. To investigate if printing quality problems are caused by the non-linear dynamics in the system, one existing design is modelled and used for evaluation. The simulations show that some mechanical parameters are critical in order to get satisfactory quality on the Braille text. Copyright © 1999 by ASME

关键词： Printing presses

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Experimental verification of the entropy based method for minimization of switching functions on pseudo ternary decision trees

Experimental verification of the entropy based method for mi...

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4th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, ITELSIKS 1999

作者： Yanushkevich, S.N. Shmerko, V.P. Stanković, R.S. Dziurzanski, P. Popel, D.V. Department of Coniputer Aided Design Systems Faculty of Computer Science and Infortnation Systems Technical University of Szczecin Poland Department of Computer Science Faculty of Electronic Engineering University of Nis Serbia Department of Computer Science State University of Informatics and Radioelectronics Minsk Belarus

ISBN: (纸本)078035768X

We present a new entropy based method for minimization of sum-of-product (SOP) expressions of switching functions. Unlike the recent results which utilize binary decision trees (DTs), we study the minimization procedure as a heuristic search based on information measures on the free pseudo ternary DTs. The main contribution of this paper is an experimental justification of the entropy based method that yields the extreme improvements compared to some recent results on application of information theory methods for SOP minimization of switching functions. In most cases, we obtained that the quality of minimization with our minimizer InfoMin-2 is the same as that produced by ESPRESSO package, but is often performed faster. © 1999 IEEE.

关键词： Entropy

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Information theoretical approach to minimization of AND/EXOR expressions of switching functions

Information theoretical approach to minimization of AND/EXOR...

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4th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, ITELSIKS 1999

作者： Shmerko, V. Popel, D. Stanković, R.S. Cheushev, V. Yanushkevich, S. Department of Computer Aided Design Systems Techinal University of Szczecin Poland Department of Computer Sicience State University of Informatics and Radioelectronics Minks Belarus Department of Computer Science Faculty of Electronic Engineering University of Nis Serbia Department of Programming Technologies State University Minsk Belarus

ISBN: (纸本)078035768X

In modern circuit design, the Shannon decomposition of switching functions is widely used. On the other hand, in information theory of telecommunication, the Shannon entropy used as a measure to represent the information in numerical values, is a key notion. In this paper, we relate these two concepts, belonging to different areas, into an approach to the minimisation of exclusive-or sum-of-products (AND/EXOR) expressions for switching functions. The Shannon decomposition, and the closely related Davio decomposition for AND/EXOR expressions are interpreted in terms of basic concepts in the information theory. Thanks to that, we have proposed an entropy based strategy for minimization of AND/EXOR expressions. We have provided a comparison and an experimental verification of this strategy with some known heuristic minimization strategies using benchmarks. In some cases, our program Info-EXOR produces extremely better results. Moreover, the information theory interpretation of classical decomposition of switching functions offers a new point of view to the existing design styles. © 1999 IEEE.

关键词： Information theory

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Multirate integration for real-time simulation of wheel loader hydraulics

Multirate integration for real-time simulation of wheel load...

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ASME 1999 design engineering Technical Conferences, DETC 1999

作者： Buzdugan, Laurenţiu I. Balling, Ole Lee, Peter Chien-Te Balling, Claus Freeman, Jeffrey S. Huck, Frank Center for Computer-Aided Design University of Iowa 229 Engineering Research Facility Iowa CityIA52242-1000 United States Department of Mechanical Engineering Center for Computer Aided Design University of Iowa 2135 Seaman's Center Iowa CityIA52242-1527 United States Caterpillar Inc. PO. Box 1875 PeoriaIL61656-1875 United States

ISBN: (纸本)9780791819777

This paper details a real-time simulation of an articulating wheel loader, which is comprised of a multibody system modeling the chassis and the bucket assembly and a set of subsystems. The hydraulic subsystem is modeled by a set of ODE's which represent the oil pressure fluctuations in the system. An Adams-Bashforth-Moulton integration algorithm has been implemented using the Nordsieck form to develop a constant step-size multirate integration scheme, modeling the interaction between the hydraulic subsystem and multibody dynamics models. An example illustrating the simulation of a wheel loader bucket operation is presented at the end of the paper. Copyright © 1999 by ASME

关键词： Wheels

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An exact method for NC verifigatldn of up to 5-axis machining

An exact method for NC verifigatldn of up to 5-axis machinin...

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ASME 1999 design engineering Technical Conferences, DETC 1999

作者： Abdel-Malek, K. Seaman, Walter Yeh, Harn-Jou Department of Mechanical Engineering Center for Computer Aided Design The University of Iowa Iowa CityIA52242 United States Department of Mathematics The University of Iowa Iowa CityIA United States Microtek International Taiwan

ISBN: (纸本)9780791819715

The motion of a cutter tool is modeled as a surface undergoing a sweep operation along another geometric' entity. A numerically controlled machining verification method is developed, based on a formulation for delineating, the volume generated by the motion of a cutting tool on the workpiece (stock). Varieties arid subvarieties that are subsets of some Eucledian space defined by the zeros of a finite number of analytic functions are computed and are characterized as closed form equations of surface patches of this volume. A topological space describing the swept volume will be built as a stratified manifold with comers. Singularities of the variety are loci of points where the Jacobian of the manifold has lower rank than maximal. It is shown that varieties appearing inside the manifold representing the removed material are due to a lower degree strata of the Jacobian. Some of the. varieties are complicated (so as not to confuse with varieties in complex Cn) and will be shown to be reducible because of their parametrization and are addressed. Benefits of this method are evident in its ability to depict the manifold and to compute a value for the volume. Copyright © 1999 by ASME.

关键词： Cutting tools

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Erratum to: Multiple sweeping using the Denavit–Hartenberg representation method

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computer-aided design 1999年第13期31卷 855-855页

作者： K. Abdel-Malek S. Othman Department of Mechanical Engineering and Center for Computer-Aided Design The University of Iowa Iowa City IA 52242 USA US National Advanced Driving Simulator and Simulation Center 2401 Oakdale Avenue The University of Iowa Iowa City IA 52242 USA

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