bluuebunny/crossref_metadata_2025_split huggingface dataset:
Method of Fundamental Solutions for Stokes Problems by the Pressure-Stream Function Formulation
Authors: Young D. L. , Wu J. T. , Chiu C. L. 
Published: May 2011

ABSTRACTThe main purpose of this paper is to investigate the pressure-stream function formulation to solve 2D and 3D Stokes flows by the meshless numerical scheme of the method of fundamental solutions (MFS). The MFS can be regarded as a truly scattered, grid-free (or meshless) and non-singular numerical scheme. By the proposed algorithm, the stream function is governed by the bi-harmonic equation while the pressure is governed by the Laplace equation. The velocity field is then obtained by the curl of the stream function for 2D flows and curl of the vector stream function for 3D flows. We can simultaneously solve the pressure, velocity, vorticity, stream function and traction forces fields. Furthermore during the present numerical procedure no pressure boundary condition is needed which is a tedious and forbidden task. The developed algorithm is used to test several numerical experiments for the benchmark examples, including (1) the driven circular cavity, (2) the circular cavity with eccentric rotating cylinder, (3) the square cavity with traction boundary conditions and (4) the uniform flow past a sphere. The results compare very well with the solutions obtained by analytical or other numerical methods such as finite element method (FEM). It is found that the meshless MFS will give a simpler and more efficient and accurate solutions to the Stokes flows investigated in this study.
The Method of Fundamental Solutions with Dual Reciprocity for thin Plates on Winkler Foundations with Arbitrary Loadings
Authors: Tsai C. C. 
Published: May 2011

ABSTRACTThis paper describes the combination of the method of fundamental solutions (MFS) and the dual reciprocity method (DRM) as a meshless numerical method to solve problems of thin plates resting on Winkler foundations under arbitrary loadings, where the DRM is based on the augmented polyharmonic splines constructed by splines and monomials. In the solution procedure, the arbitrary distributed loading is first approximated by the augmented polyharmonic splines (APS) and thus the desired particular solution can be represented by the corresponding analytical particular solutions of the APS. Thereafter, the complementary solution is solved formally by the MFS. In the mathematical derivations, the real coefficient operator in the governing equation is decomposed into two complex coefficient operators. In other words, the solutions obtained by the MFS-DRM are first treated in terms of these complex coefficient operators and then converted to real numbers in suitable ways. Furthermore, the boundary conditions of lateral displacement, slope, normal moment, and effective shear force are all given explicitly for the particular solutions of APS as well as the kernels of MFS. Finally, numerical experiments are carried out to validate these analytical formulas.
Dynamic Responses of Beams with a Flexible Support Under a Constant Speed Moving Load
Authors: Lin H.-P. 
Published: May 2011

ABSTRACTThis paper deals with the linear dynamic responses of beams with a flexible support under a moving load with a constant speed. The entire system is modeled as a two-span beam and each span of the continuous beams is assumed to obey the Euler-Bernoulli beam theory. Considering the compatibility requirements on the flexible constraint, the relationships between two segments can be obtained. By using a transfer matrix method, the characteristic equation of the entire system can then be determined. The forced responses of the system under a moving load can then be obtained through modal expansion theory. Some numerical results are presented to the effects of support stiffness and the different speeds of the moving load.
C1 in Displacement Coefficient Method for Taiwan to Estimate Maximum Inelastic Displacement Demands of Existing Structures
Authors: Lin Y.-Y. 
Published: May 2011

ABSTRACTThe coefficient C1 in the displacement coefficient method of FEMA-273/356 is the modification factor to relate the expected maximum displacements of elasto-plastic inelastic SDOF systems to displacements calculated for linear response. It permits the estimation of maximum inelastic displacements from maximum elastic displacements for structures with known lateral strength (usually, the existing structures). Recently, an improved C1 has been presented in FEMA-440 because it was shown that the C1 in FEMA-273/356 underestimates the maximum inelastic displacement demands of structures significantly. However, the improved C1 in FEMA-440 was derived from the earthquake ground motions recorded in California. In addition, it was mentioned in FEMA-440 that “caution should be used when extrapolating the results presented in the report for ground motions and site conditions that differ”. Because the characteristics of earthquakes occurred in Taiwan are different from those occurred in California, the coefficient for used in Taiwan needs to be modified. The objective of this paper is to propose appropriate C1 for use in Taiwan.
Thickness Effect on Low-Aspect-Ratio Wing Aerodynamic Characteristics at a Low Reynolds Number
Authors: Hsiao F. B. , Lin C. Y. , Liu Y. C. , Wang D. B. , Hsu C. C. , Chiang C. H. 
Published: May 2011

AbstractThis paper presents the study of aerodynamic performance about low-aspect-ratio wings at a low Reynolds number in wind tunnel testing. The aerodynamic properties, including lift, total drag, lift-to-drag ratio and induced drag were measured and analyzed for detailed investigations. Two forms of nonlinear equations of lift curves were reported for comparison. The effect of airfoil thickness was found to be significant on aerodynamic characteristics for all wings tested. The lift due to tip vortices was prominent for wings of AR =1.0 and their stall angles were all larger than 20°, which was mainly augmented by tip vortices shed from the wing tips.
Long-Wave Perturbation Method to Investigate Nonlinear Stability of the Thin Power Law Liquid Film Flowing Down on a Vertical Cylinder
Authors: Cheng P. -J. , Liu K. -C. 
Published: May 2011

ABSTRACTThe influence of both the flow index and the cylinder size on the nonlinear hydrodynamic stability of a thin power law liquid film flowing down along the surface of a vertical cylinder is investigated. The long-wave perturbation method is employed to solve for generalized nonlinear kinematic equations with a free film interface. The normal mode approach is first used to compute the linear stability solution for the film flow. The method of multiple scales is then used to obtain the weakly nonlinear dynamics of the film flow for stability analysis. The stability criteria are discussed theoretically and numerically and stability diagrams are obtained. The modeling results indicate that by increasing the flow index and increasing the radius of the cylinder the film flow can become relatively more stable as traveling down along the vertical cylinder.
MHD Mixed Convection of Viscoelastic Fluid Over a Stretching Sheet with Ohmic Dissipation
Authors: Hsiao K.-L. 
Published: May 2011

AbstractA magnetic hydrodynamic (MHD) mixed convection of an incompressible viscoelastic fluid over a stretching sheet with ohmic dissipation is studied. The buoyant effect and the electric number E1 couple with magnetic parameter M to represent the dominance of the ohmic effect are presented in governing equations which is the main contribution by this study. The similarity transformation, the finitedifference method have been used to analyze the present problem. The numerical solutions of the flow velocity distributions, temperature profiles and the important wall unknown values of f″(0) and θ′(0) are carried out.
Analytical Predictions of Strong Pseudo-Steady Mach Reflections for the Polyatomic Gas: SF6
Authors: Liu J. J. 
Published: May 2011

ABSTRACTStrong pseudo-steady Mach reflections in sulfur hexafluoride (SF6) are analyzed using the three-shock and local three-shock theories, where both the vibrationally-frozen (γ = 1.333) and -equilibrated (γ = 1.093) perfect-gas models are used to compare with existing experiments. The ranges of the incident shock Mach number and reflecting wedge angle studied are 1.49 ≤ Ms ≤ 5.95 and 10° ≤ θω ≤ 42°, respectively. It is found that predicted angles between the incident and reflected shocks from the local three-shock theory using the vibrationally-equilibrated fictitious perfect-gas model (i.e., γ = 1.093) agree closely with those, currently available in literature, measured experimentally; while these predicted angles obtained using the vibrationally-frozen perfect-gas model (i.e., γ = 1.333) differ significantly from the existing experiments. Taking the convex Mach stem curvature at the triple point into consideration, it is shown that both the triple point trajectory angle and the angle between the incident and reflected shocks of strong pseudo-steady Mach reflections in SF6 can be more accurately determined for wide ranges of Ms and θω from the three-shock theory using the vibrationally-equilibrated fictitious perfect-gas model than those without considering this effect.
Motion of Miscible Magnetic Fluids in a Vertical Capillary Tube
Authors: Chen C.-Y. , Lin H.-C. , Tsai W.-K. , Lin C.-H. 
Published: May 2011

AbstractAn experimental study of miscible magnetic fluid motion in a vertical capillary tube is presented. Transporting ferrofluids is dominated by a dimensionless magnetic number Ma, which characterizes the ratio of upward magnetic force to the downward gravity. Two distinct stages of motion, referred to as the sub-critical mode of finite lift and the effective transportation, are identified. These two modes are determined by the values of the sub-critical magnetic number Masub and critical magnetic number Macr respectively. For the cases of sub-critical mode (Masub < Ma < Macr), the ferrofluids are lifted to quasiequilibrium heights, which are nearly proportional to the magnetic number Ma. As for the situations of effective transportation (Ma > Macr), a penetrating finger of ferrofluids is formed similar to the conventional miscible displacements. A dimensionless proportionality of fingertip velocity ν, magnetic number Ma and field distribution profile fz is obtained as ν ∼ Ma1/2fz by scaling arguments. This proportional correlation shows a good agreement with the experiments.
Nondestructive Damage Detection of Two Dimensional Plate Structures Using Modal Strain Energy Method
Authors: Hu H.-W. , Wu C.-B. 
Published: May 2011

AbstractA nondestructive detection method of surface cracks in two dimensional plate structures using modal strain energy method is investigated in this paper. Experimental modal analysis (EMA) is conducted on an aluminum alloy 6061 thin plate to obtain the mode shapes before and after damage under a completely free boundary condition. The measured mode shapes are used to compute the strain energy of the plate. Limited by the measured points, a differential quadrature method is employed to compute the partial differential terms in strain energy formula. A damage index is then defined based on strain energy ratio of the plate before and after damage. This damage index is employed to identify the location of surface crack in plate structure. A finite element analysis (FEA) is also performed to access this approach and demonstrate a feasible process for the experimental work. Good correlation between FEA and EMA results is obtained. The damage index obtained from both FEA and EMA successfully identify the location of surface crack in the aluminum plate. Only few measured mode shapes of the plate are required in this method, which provides a quick, flexible, inexpensive and nondestructive technique to identify the damagein local and global 2D plate structures.
Buckling and Postbuckling Analyses of a Skew Plate
Authors: Liao H. W. , Huang H. Y. 
Published: May 2011

AbstractThe applications of skew plates in the construction of aerospace structures are well known. The critical buckling load and post-buckling strength are two important design parameters of skew composite laminates. In this study, the refined buckling and nonlinear postbuckling solutions of a homogenous isotropic skew plate based on polynomial expansions of various degrees have been examined. Numerical results based on high-order Rayleigh-Ritz solutions are presented for certain type of oblique plates.
Predicting Fatigue Initiation Life of Sn/3.8Ag/0.7Cu Solder using Endochronic Cyclic Damage-Coupled Viscoplastic Theory
Authors: Lee C. F. , Lee Z. H. 
Published: May 2011

AbstractThis paper studied cyclic behavior Sn/3.8Ag/0.7Cu solder with dendritic microstructure. A cyclic damage factor D under constant strain amplitude fatigue tests, was defined by using the reducing rate of maximum cyclic tensile stress σa. The critical cyclic damage DC and it's fatigue initiation life NI were determined very consistently by using separately the experimental σavs. N curves and the percolation theory. The endochronic cyclic damage-coupled viscoplastic theory proposed by the 1st author was used to simulate cyclic stress-strain hysteresis loops with damage under strain amplitude (εa) 0.8% at 298K. The results were in very good agreement with data. Combining the evolution equation of intrinsic damage and the computed cyclic stress-inelastic strain relation, a modified Coffin-Manson relationship was derived. By setting DC = 0.3, it predicted very effectively the NI data under σa from 0.2% to 1.0%.
A Study of Parallel Efficiency of Modified Direct Algorithm Applied to Thermohydrodynamic Lubrication
Authors: Wang N. , Tsai C.-M. , Cha K.-C. 
Published: May 2011

AbstractThis study examines the parallel computing as a means to minimize the execution time in the optimization applied to thermohydrodynamic (THD) lubrication. The objective of the optimization is to maximize the load capacity of a slider bearing with two design variables. A global optimization method, DIviding RECTangle (DIRECT) algorithm, is used. The first approach was to apply the parallel computing within the THD model in a shared-memory processing (SMP) environment to examine the parallel efficiency of fine-grain computation. Next, a distributed parallel computing in the search level was conducted by use of the standard DIRECT algorithm. Then, the algorithm is modified to provide a version suitable for effective parallel computing. In the latter coarse-grain computation the speedups obtained by the DIRECT algorithms are compared with some previous studies using other parallel optimization methods. In the fine-grain computation of the SMP machine, the communication and overhead time costs prohibit high speedup in the cases of four or more simultaneous threads. It is found that the standard DIRECT algorithm is an efficient sequential but less parallel-computing-friendly method. When the modified algorithm is used in the slider bearing optimization, a parallel efficiency of 96.3% is obtained in the 16-computing-node cluster. This study presents the modified DIRECT algorithm, an efficient parallel search method, for general engineering optimization problems.
The Endochronic Viscoplasticity for Sn/3.9Ag/0.6Cu Solder Under Low Strain Rate Fatigue Loading Coupled with Thermal Cycling
Authors: Lee C. F. , Lee Z. H. , Ou S. H. 
Published: May 2011

AbstractIn this paper a wide range of temp. dependent kernel function ρ(Z) and the strain-rate function h(, T) in the Endochronic viscoplasticity were established first by using experimental steady hysteresis loops of Wei et. al., for Sn/3.9Ag/0.6Cu Solder at fixed 298K or 373K and strain rate at 10−3, 10−4 and 10−51/s; and then extended to predict the thermomechanical behavior of solder under constant low strain rate (10−51/s), from 0 to 1% max. strain fatigue loading with in-phase thermal cycling between 298K and 373K.A novel approach in the theory to account for the microstructural changes enhanced by the stressassisted grain boundary diffusion mechanism during thermal cycling was proposed by using a partial relaxation function h1(T) of back stress (i.e. ρ0 in ρ(Z)).The theoretical results were in very well agreement with experimental data. These results and the out-phase results from the present theory were new and might be used as references to compare with results derived from other theories.
Leg and Joint Stiffness in Patients with Bilateral Medial Knee Osteoarthritis During Level Walking
Authors: Wei I-P. , Hsu W.-C. , Chien H.-L. , Chang C.-F. , Liu Y.-H. , Ho T.-J. , Wang T.-M. , Lin J.-G. , Lu T.-W. 
Published: May 2011

AbstractKnowledge of the control of the musculoskeletal system in patients with knee osteoarthritis (OA) during gait is helpful for the development of intervention programs in the management of these patients. The current study aimed to investigate the leg and joint stiffness, aswell as the associated joint kinematics and kinetics, in patients with bilateral medial knee OA during gait. Joint angles, moments and stiffness, as well as leg stiffness from fifteen patients with bilateral knee OA and fifteen normal controls during level walking, were obtained and their values at the beginning and end of single leg stance were compared using a t-test.Patients with knee OA were found to modulate their leg and joint stiffness through acquired specific biomechanical strategies in order to maintain normal temporal-spatial patterns of gait. During weight acceptance, they increased their leg stiffness with increased knee stiffness but unalterd hip and ankle stiffness. During weight release, they modulated their hip and ankle kinetics with increased knee and ankle stiffness to improve the control stability of the limb with unaltered leg stiffness. It is suggested that muscle strengthening exercise intervention and/or rehabilitation for patients with knee OA should focus on activities that develop and/or maintain functions not only of the knee, but also of the overall lower extremity.
Experimental Study of the Heat Transfer Across Periodically Contacting Surfaces
Authors: Goudarzi K. , Shojaeefard M. H. 
Published: May 2011

AbstractAn experimental study for determining the thermal contact conductance between two periodically contacting surfaces is presented. The influence of the frequency of contact upon the thermal contact conductance is investigated. Also, the results show that the thermal contactconductance decreases as the frequency of contact increases. The experimental results obtained from present work are in agreement with the previous published data.
Application of Neural Network and Genetic Algorithm to the Optimum Design of Perforated Tube Mufflers
Authors: Chiu M.-C. , Chang Y.-C. 
Published: May 2011

AbstractResearch on new techniques of perforated silencers has been well addressed. However, the research work on shape optimization for a volume-constrained silencer within a constrained machine room is rare. Therefore, the optimum design of mufflers becomes an essential issue. In this paper, to simplify the optimum process, a simplified mathematical model of the muffler is constructed with a neural network using a series of input design data (muffle dimensions) and output data (theoretical sound transmission loss) obtained by a theoretical mathematical model (TMM). To assess the optimal mufflers, the neural network model (NNM) is used as an objective function in conjunction with a genetic algorithm (GA). Moreover, the numerical cases of sound elimination with respect to pure tones (500, 1000, 2000Hz) are exemplified and discussed.Before the GA operation can be carried out, the accuracy of the TMM is checked by Crocker's experimental data. In addition, both the TMM and NNM are compared. It is found that the TMM and the experimental data are in agreement. Moreover, the TMM and NNM confirm.The results reveal that the maximum value of the sound transmission loss (STL) can be optimally obtained at the desired frequencies. Consequently, it is obvious that the optimum algorithm proposed in this study can provide an efficient way to develop optimal silencers.
An Innovative Technique for Simultaneous Measurement of Three-Dimensional Kinematics and Induced Flow of a Swimming Fish
Authors: Ting S.-C. , Yang J.-T. 
Published: May 2011

ABSTRACTIn this work, we introduced an innovative technique that enables simultaneous measurement of the 3D kinematics and 2D–3 Components fluid velocities of the induced flow of a swimming fish, which greatly advanced the experimental technique for research in fish biomechanics. This technique was theoretically based on the combined use of new reconstruction formulas of position and the calibration polynomials of stereo-DPIV, employing only two cameras in the imaging system. Both kinematic and hydrodynamic characteristics of a fish executing three-dimensional and complicated locomotion are readily and accurately revealed. Measuring simultaneously 3D kinematics and hydrodynamics is significantly important for an accurate investigation of fish biomechanics because fish motions are three-dimensional. We demonstrate results of 3D kinematics and fluid velocity fields measured in the wake of a maneuvering pectoral fin of a fish, which proves the effectiveness and usefulness of this technique. The application of this technique is extendable to biomechanics research concerning locomotion of both swimming and flying animals.
Investigation of Dynamic Responses for Piezoceramic Plates in Resonance by Using Fiber Bragg Grating
Authors: Chuang K.-C. , Ma C.-C. , Liang C.-Y. 
Published: May 2011

ABSTRACTA fiber Bragg grating (FBG) sensor system which can simultaneously measure the point-wise, out-of-plane and in-plane dynamic displacements is proposed. A demodulation system based on the fiber Bragg grating filter is used. The steady-state responses of particle motions of a piezoceramic plate measured by the FBG out-of-plane and in-plane displacement sensors are simultaneously compared with those obtained by a laser Doppler vibrometer (LDV) and a surface-mounted FBG strain sensor, respectively. The integration of the FBG displacement sensor with a dynamic signal analyzer (FBG-DSA) forms a measurement system which has the ability to acquire the frequency response of a piezoceramic plate. An LDV-DSA system and an impedance analyzer are used to compare the results obtained from the dynamic signal analyzer combined with the out-of-plane FBG sensor (OFBG-DSA) and the in-plane FBG sensor (IFBG-DSA), respectively. The experimental results of the impulse excitation as well as the random excitation of the piezoceramic plate are also presented. To explain the experimental results, an optical full-field measurement technique called amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and FEM numerical calculations are also used to provide full-field vibration mode shapes of the piezoceramic plate. These results indicate that the proposed displacement sensor system has the multiplexing capability to measure the dynamic displacements up to 45kHz.