bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study on the Safety of the Shear Capacity Design of Reinforced Concrete Beam-Column Joints
Authors: Lu W.-Y. 
Published: May 2011

AbstractThe shear failure probabilities of reinforced concrete beam-column joints have been investigated by Monte Carlo method. The theoretical shear strength of joints is based on the softened strut-and-tie model proposed by Hwang and Lee (2002). The random variables included in this study are the strengths of concrete, the ultimate compression strain of concrete, the strengths of reinforcement, the dimensions of cross-section, and the model error of theoretical shear strength of joints. The shear failure probabilities of joints with SD 280 flexural reinforcement in the beams designed using the ACI Code are all higher than 0.04. The joints designed according to the softened strut-and-tie model are safer than those designed according to the ACI Code. The shear failure probabilities of exterior joints are higher than those of interior joints. The shear failure probabilities of joints with SD 280 flexural reinforcement in the beams are higher than those of joints with SD 420 flexural reinforcement.
Application of Biot Theory in Analyzing the Sound Insulation Characteristic of Honeycomb Sandwich Panels
Authors: Wang C.-N. , Tang M.-J. , Tse C.-C. 
Published: May 2011

AbstractThe purpose of this paper is to apply Biot theory on analyzing honeycomb core to investigate the sound insulation characteristics of honeycomb sandwich panels. At first, the honeycomb core was regarded as a porous material and the sandwich panel is made of layered media. Thus Biot theory developed for fluid saturated porous material is adopted to analyze the waves propagated in honeycomb core. Then the transfer matrix for waves propagated between two ends of each panel is established. The combination of these related matrices can be conducted on evaluating the sound propagation characteristic in the layered media. The comparison of the transmission loss between the available experimental measurements and numerical predictions shows that the present method is reliable. With the present method, the numerical results reveal that the coincident frequency decreases apparently as the thickness of core increases. Therefore, the transmission loss is also increased in the analyzed frequency range. Further, the effect of core density and cell size are also investigated.
Studying Three-Dimensionality of Vortex Shedding Behind a Circular Cylinder with Mems Sensors
Authors: Tu J. K. , Miau J. J. , Wang Y. J. , Lee G. B. , Lin C. 
Published: May 2011

AbstractExperiments were made with 14 MEMS sensors situated along the span of a circular cylinder whose aspect ratio was 5. The signals of the MEMS sensors were sampled simultaneously as flow over the cylinder at Reynolds numbers of 104. The results of Wavelet analysis of the signals indicate that the percentage of time during which strong three-dimensionality of vortex shedding was detected is about 10%.As noted, strong three-dimensionality took place when the fluctuating amplitude of the signals was severely modulated and the vortex shedding frequency reduced appeared abnormally high or low. Further noted was that the addition of a splitter plate of 0.5 or one diameter in length behind the circular cylinder was not able to suppress the three-dimensionality of the flow.
Effects of Structural Behavior on Electromagnetic Resonance Frequency of a Superconducting Radio Frequency Cavity
Authors: Lin M.-C. , Wang Ch. , Chang L.-H. , Yeh M.-K. , Kao F.-S. 
Published: May 2011

AbstractDuring operation, a superconducting radio frequency cavity is cooled down to below critical superconducting temperature by liquid helium. Thus it is under external pressure by liquid helium while an ultrahigh vacuum inside. Being a niobium-made shell structure, the SRF cavity's shape and consequently the electromagnetic resonance frequency are sensitive to external load variations. A CESR-III 500MHz superconducting radio frequency cavity is illustrated to investigate this relationship. A simulation that links the calculations on mechanical structure and radio frequency electromagnetic field with the finite element code ANSYS® is demonstrated herein. The changes of electromagnetic resonance frequency associated with external loads and mechanical properties of niobium are studied systematically. A complete understanding on the mechanism is thus achieved. The computed results also indicate that the electromagnetic resonance frequency increases as the cavity is either cooled to cryogenic temperature or stretched longitudinally, while the reduction of the helium vessel pressure also raises the resonance frequency. Besides, the electromagnetic resonance frequency shift is ruled by the coefficient of thermal expansion when the cavity is cooled from room temperature to liquid helium temperature. Young's modulus and thickness of the cavity wall dominate the structure stiffness and thus also affect the frequency shift.
Physical Aging in Long Term Creep of Polymeric Composite Laminates
Authors: Hu H. W. 
Published: May 2011

AbstractThis paper presents a complete approach to characterize physical aging in long term creep of composite laminates using short term creep test. Carbon/epoxy composite IM7/977−3 was use to make the coupon specimens of unidirectional fiber orientation and symmetrical laminates. Creep tests were conducted on the specimens to obtain momentary compliances at isothermal conditions. Physical aging in elastic and in creep compliances were modeled respectively. Momentary creep compliances in various aging times were shifted to superpose a reference curve by introducing shift factors for both relaxation time and shape factor of a power law model. Linear relations between shift factors and aging time in log-log scale were found and defined as shift rates. By using reference curve associated with the shift rates, momentary creep compliance in any given aging time can be predicted. By introducing a time dependent shift factor, momentary creep compliance can be modified and turned into an effective time model, which can successfully predict the long term creep of composite laminates at isothermal aging. This approach only requires the test data of momentary creep, and no material properties in each lamina are needed.
Evaluation of Nonlinear System Parameters by Stochastic Spectral Method
Authors: Chang T.-P. , Liu M.-F. 
Published: May 2011

AbstractA stochastic spectral method is proposed to estimate the nonlinear parameters of a system subjected to random excitation. Sometimes, it is impossible to measure the excitation process; therefore, estimation must then be based on the response measurement only, in conjunction with a stochastic model of the excitation. The concept of this method is to establish an objecting function involving the unknown parameters through frequency domain analysis, and then we can minimize the objecting function to estimate the unknown parameters by using standard nonlinear optimization algorithm. Finally, the validation of the proposed method is accomplished through many simulations and it can be concluded that the proposed method is applicable to a variety of different problems.
A Study on Mass Transfer in the Cathode Gas Channel of a Proton Exchange Membrane Fuel Cell
Authors: Jeng K.-T. , Wen C.-Y. , Anh L. D. 
Published: May 2011

AbstractA two-dimensional, transient mathematical model for the mass transfer of a reactant gas in the cathode gas channel of a PEMFC is developed. This model accounts concurrently for gas flow and multicomponent species (oxygen, water vapor and nitrogen) transport in the gas channel at specified cell current densities. The governing equations along with the boundary and initial conditions are solved numerically by using finite-difference methods. The numerical results show that the oxygen and water vapor concentrations in the gas channel are strong functions of stoichiometry. However, at a fixed stoichiometry, the current density has only a slight influence on the concentration variations. The fully-developed Sherwood number for oxygen mass transfer in the gas channel was found to be 6.0, which agrees well with the Sherwood number estimated from the correlation between mass and heat transfer. The current mathematical model and numerical results are confirmed by the experimental verification of the location of first appearance of liquid water at the channel/GDL interface.
Train-Induced Vibration Control of Simple Beams Using String-Type Tuned Mass Dampers
Authors: Yau J.-D. 
Published: May 2011

AbstractSince a long-term oscillation of a tuned mass damper (or TMD) in vibration control may impair the spring stiffness of the TMD, this phenomenon will directly down-tune the target frequency of the TMD. For this reason, this study intends to present a string-type tuned mass damper (or STMD) with an adjustable tuning frequency to mitigate the resonant response of a simple beam due to moving loads. The STMD device is installed inside the inner room of a bridge box girder and is composed of a distributed spring-dashpot-mass with a stretched string. Considering a linear beam-STMD model, a generalized two-degrees-of-freedom system is employed to determine the optimum tuning frequency condition and parameters of the STMD in vibration control. Compared with a traditional TMD device, the proposed STMD has the advantage of being adjustable in tuning frequency. From the numerical examples, the results indicate that the proposed STMD is a potential vibration control device in suppressing the train-induced vibration of railway bridges. Even though the tuning frequency of the STMD down-deviate from the target one by 10%, the control effectiveness of such a detuning STMD can still achieve about 90% as that of an optimal STMD by tuning its frequency to fit the optimum tuning frequency condition presented in this study.
The Effect of Flow Velocity on Microcantilever-Based Biosensors
Authors: Wu M.-C. , Chang J.-S. , Wu K.-C. , Lin C.-H. , Wu C.-Y. 
Published: May 2011

ABSTRACTThis work focuses on studying the effect of flow velocity on microcantilever-based biosensor by numerical simulation. The microcantilever sensors used in detecting biomolecules have attractive advantages like cost efficiency, real-time and ability of fabricating in array. Both rectangular and triangular shapes of a general model of microcantilever beam are considered. Several important physical phenomena are obtained. Comparing with the first order Langmuir theory, we have calculated the effect on the reactive rate, produced concentration, the distribution of concentration and deflection in the z axis by solving these physical coupled problem involving flow field, concentration field and chemical reaction on the reaction surface. It is found numerically that the transportation of analyte, reactive rate, the distribution of concentration and deflection in the z axis are all effected by changing the flow velocity. The result has shown that flow velocity is an important factor for this biosensor.
Hybrid Flux-Splitting Finite-Volume Scheme for the Shallow Water Flow Simulations with Source Terms
Authors: Guo W.-D. , Lai J.-S. , Lin G.-F. 
Published: May 2011

AbstractThe extension of the hybrid flux-splitting finite-volume (HFF) scheme to the shallow water equations with source terms is presented. Based on the monotonic upstream schemes for conservation laws (MUSCL) method, the scheme is second-order-accurate both in space and time. An accurate and efficient surface gradient method (SGM), in conjunction with the HFF scheme, is adopted for the discretization of source terms, including the bed slopes and friction slopes. The resulting scheme has several desirable properties: ease of implementation, satisfaction of entropy condition, sharp shock resolution and preservation of well-balancing. The HFF scheme with SGM is verified through the simulations of steady transcritical flow over a hump and steady flow over an irregular bed. Besides, the effects of the limiter functions, the grid sizes and the Manning roughness coefficients on the simulated results are investigated for the steady transcritical flow problems. Using the laboratory measurements, the scheme is also applied to the dam-break flows: with an adverse slope, with a triangular hump, and with a constriction. Furthermore, the HFF scheme is employed in the simulation of typhoon flood flow with natural-irregular river topography to demonstrate the practical engineering application. The results show good agreements compared with the exact solutions, the experimental data and the field measurements.
Drag Force on a Sphere Moving in Low-Reynolds-Number Pipe Flows
Authors: Lee S.-H. , Wu Tzuyin 
Published: May 2011

AbstractIn this paper, the drag force on a sphere moving constantly along the centerline of a circular pipe filled with viscous fluid (the falling-sphere problem) under low Reynolds number condition is investigated via numerical calculation. The incompressible Navier-Stokes equations are formulated in a pseudocompressibility form. The numerical scheme makes use of finite-volume method and the numerical flux terms are evaluated using the Total-Variation Diminishing (TVD) strategy commonly applied to the compressible flow. Steady solution is obtained by marching (iterating) in time until the artificial time derivative of pressure term in the continuity equation drops to zero.In the calculation, six different Reynolds number (Re) ranging from 0.1 to 1 and seven different pipe-to-sphere diameter ratios (D/d) ranging from 5 to 40 are selected to study the pipe-wall effect. In each case, the drag force on the sphere is evaluated and the results are compared with the existing approximate theoretical values derived from correcting the Stokes' formula. Both results agree in trend, but with noticeable deviation in values, particularly for cases with large pipe-to-sphere diameter ratios. The deviation is due to the fact that theoretical values were based on the solution to the linearized Navier-Stokes equations (Stokes' creeping-flow equations), while the fully nonlinear form of the Navier-Stokes equations are adopted in the present calculations. Finally, a least-square regression technique is applied to collapse the calculated results into a single expression exhibiting the functional relationship between the drag force, Reynolds number (Re), and the pipe-to-sphere diameter ratio (D/d).
Steady Motion of a Finite Granular Mass in a Rotating Drum
Authors: Tai Y.C. , Hutter K. , Gray J. M. N. T. 
Published: May 2011

ABSTRACTThe Savage-Hutter (SH) theory (1989) of dense granular avalanche flow uses an earth pressure coefficient Kx which depends on the internal angle of friction and the bed friction angle but assumes different values in diverging and converging flows. So the earth pressure coefficient is undefined when the strain rate ∂u/∂x changes sign. Steady plane flow of a finite mass of a cohesionless granular material in a permanently rotating drum admits an exact solution of the SH-equations at ∂u/∂x = 0 provided the value for Kx is prescribed. However, avalanche profiles depend on the values of Kx. Experiments on avalanche shapes in steady rotating drums offer therefore a possibility to identify the value of Kx at zero strain rate.
Reflections on Nonlinear Dynamics of Machines and Structures
Authors: Moon Francis C. 
Published: May 2011

ABSTRACTIn this short note a comparison is made between the methodology of nonlinear analysis in machine systems versus structural systems. Because of strong nonlinearities in machines with parts in relative motion, chaotic-like dynamics are more likely to occur in complex multi-body machines than in structural systems. Furthermore, it is conjectured that well designed machines have evolved to where a small amount of chaos is always present and is sometimes desired.
Natural Vibrations of Repetitive Structures
Authors: Wang Dajun , Wang C.-C. 
Published: May 2011

ABSTRACTNatural vibration frequencies and modes of repetitive structures, including symmetric, periodic, linking structures, are considered in this work. By using the repetition of the identical parts, we reduce the eigenvalue problem of the structure to a set of eigenvalue problems of lower dimensions associated with the parts. Special forms and properties of the modes of natural vibrations are observed.
Investigations of Thermo-Acoustic Instabilities by Direct Acoustic Admittance Measurements
Authors: Chen Tzeng-Yuan , Chen Man-Ge 
Published: May 2011

ABSTRACTThis research applied the method of direct acoustic admittance measurement to investigate effects of the flame character and the burner acoustic admittance on the flame-driving behavior. The acoustic admittance data were obtained by directly measuring the amplitudes of pressure and velocity oscillations, and the phase relations between the pressure and velocity oscillations. Results of this research reveal that the flame-driving characteristic is mainly dominated by the nonreactive burner admittance not the flame. Whether the flame is to drive or damp the acoustic field is detcrmined by the acoustic admittance of the burner system. The flame equivalence ratio plays a role mainly in determining the magnitude of the flame driving/damping.
Creeping Flow Relative to a Porous Spherical Shell
Authors: Chen Ming-Da , Li Wang-Long 
Published: May 2011

ABSTRACTIn this study, the problem of creeping flow relative to an isolated porous spherical shell has been examined. The Brinkman-extended Darcy equations and the Stokes' equations are utilized to model the flow in the porous region (shell region) and free fluid region (inside the core and outside the shell), respectively. The stress jump boundary conditions at the porous media/free fluid interfaces are included and the exact solution has been found. The drag experienced by the porous shell has been discussed for various jump parameters and shell thickness.
Importance of Nonreactive Burner Acoustic Admittance on Thermo-Acoustic Instability
Authors: Chen Tzeng-Yuan , Chen Chien-Pang 
Published: May 2011

ABSTRACTThe importance of nonreactive acoustic admittance at a burner exit plane on the flame-driving characteristic was discussed using the measured phase difference between the velocity and pressure oscillations, and the acoustic wave structure inside the duct. Also, the flame-driving characteristics were investigated by flame radiation measurements, and results were compared with those obtained previously from admittance studies. Results show that the comparisons are in good agreement. Also, the flame-driving characteristics are closed related to the acoustic wave structure at the burner exit plane, and could be qualitatively predicted by knowing the imaginary part of nonreactive burner acoustic admittance.
Three-Dimensional Finite Element Analysis of Frictional Contact for Belt Transmission Systems
Authors: Shieh Chyuan-Jau , Chen Wen-Hwa 
Published: May 2011

ABSTRACTThis work presents a rigorous three-dimensional finite element procedure to analyze belt transmission systems. The frictional contact behavior between the belt and the pulley, which accounts for the power loss of the system and the wear of the belt, is investigated in detail. In addition to adopting the transformation matrix to satisfy the geometric conditions on the contact surfaces, the proposed procedure also uses the modified elements with incremental Wilson displacement modes to improve the accuracy due to bending at the end zones of the contact area for the belt. To demonstrate the accuracy and feasibility of the proposed procedure, the analyses for flat and V belt drives are carried out. Excellent correlations between the calculated results and referenced theoretical/experimental solutions are found. The influences of friction coefficients on the deformation, normal and tangential contact forces on the contact surfaces are studied as well. Those will be helpful for the estimation of wear properties and operation efficiency for belt transmission systems.
Peculiar Appearance of Nearly Symmetrical Tidal Flooding Time Along the Western Coast of Taiwan
Authors: Juang Wen-Jye , Lin Ming-Chung , Liou Wen-Jiunn 
Published: May 2011

ABSTRACTDuring the past several decades, nearly symmetrical tidal appearances, both the time of high water elevation and the tidal range, were noted along the western coast of Taiwan. Research corresponding to anomalous amplifications of tidal range have been well studied by Lin, et al. [1,2], but the particular symmetrical tidal appearance of high water time has not yet been clarified. In this paper, we firstly apply a harmonic analysis to tidal data compiling. Based on the results, the important symmetric appearances of high water time and tidal range can be located. Emphasis is given on the investigation of symmetrical distribution of high water time by superposing two progressive waves that interfere on a topographic shelf with specific width. A conceptual configuration of co-oscillating standing tides is proposed to demonstrate the symmetrical tidal range distributing in the space domain and oscillating in the time domain.
3C Duct Design Method
Authors: Shiu Huan-Ruei , Ou Feng-Chu , Chen Sih-Li 
Published: May 2011

AbstractA new 3C duct design method is proposed for designing a high quality, energy-efficiency cost-effective air duct system. It not only considers the demand of volume flow rate, but also takes into consideration a number of issues including system pressure balance, noise, vibration, space limitation and total system cost. This new method comprises three major calculation procedures: initial computer-aided design (CAD), computer-aided simulation (CAS) and correction processes (CP). An example is presented in this study to understand the characteristics of 3C method. It shows that 3C duct design method provides a simple computation procedure for an optimum air duct system. It also shortens the design schedule, prevents human calculation errors, and reduces the dependence on designer experience. In addition to apply in a new duct system design, 3C duct design method is also a powerful design tool for the expansion of an existing duct system.
A Hybrid Method for Analyzing the Dynamic Responses of Cavities or Shells Buried in an Elastic Half-Plane
Authors: Yeh Chau-Shioung , Teng Tsung-Jen , Shyu Wen-Shinn , Tsai I-Chang 
Published: May 2011

AbstractIn this paper, based on a variational formalism which originally proposed by Mei [1] for infinite elastic medium and extended by Yeh, et al. [2,3] for elastic half-plane, a hybrid method which combines the finite element and series expansion method is implemented to solve the diffraction of plane waves by a cavity buried in an elastic half-plane. The finite domain which encloses all inhomogeneities including the cavity can be easily formulated by finite element methods. The unknown boundary data obtained by subtracting the known free fields from the total fields which include the boundary nodal displacements and tractions at the interface between the finite domain and the surrounding elastic half-plane are not independent of each other and can be correlated through a series representation. Due to the continuity condition at the interface, the same series representation is still valid for the exterior elastic half-plane to represents the scattered wave. The unknown coefficients of this series are treated as generalized coordinates and can be easily formulated by the same variational principle. The expansion function of the series is composed of basis function. Each basis function is constructed from the basis function for an infinite plane by superimposing an additional homogeneous reflective term to satisfy both traction free conditions at ground surface and radiation conditions at infinity. The numerical results are made against those obtained by boundary element methods, and good agreements are found.