bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibration and Buckling Analyses of Beams by the Modified Differential Quadrature Method
Authors: Chou Y.-T. , Choi S.-T. 
Published: May 2011

ABSTRACTIn this paper the modified differential quadrature method (MDQM) is proposed for static and vibration analyses of beams. Modified weighting matrices are developed and a new formulation process is presented for incorporating boundary conditions such that the numerical error induced by using the δ-method in the original DQM is reduced. The present method is applied to various beam problems, such as static deflections of Euler beams, buckling loads of columns, and free vibrations of Timoshenko beams. Numerical results of the present method are shown to have excellent accuracy when compared to exact values and are more accurate than those obtained by the original DQM. The accuracy and efficiency of the present method have been demonstrated.
Vibration Control of a Beam Using the Nearly Optimal Control Algorithm with a Disturbance Force Observer
Authors: Wang Der-An , Huang Yii-Mai 
Published: May 2011

ABSTRACTActive vibration control of a flexible beam subjected to arbitrary, unmeasurable disturbance forces is investigated in this paper. The concept of independent modal space control is adopted. Both the feedforward and feedback control is implemented here to reduce the beam vibration. Because of the existence of the disturbance forces, the feedforward control is applied by employing the idea of force cancellation. A modal space disturbance force observer is then established in this paper to observe the disturbance modal forces for the feedforward control. For obtaining the feedforward and feedback control gains with the optimal sense, the nearly optimal control law is derived, where the modal disturbance forces are regarded as additional states. The vibration control performances and the asymptotic properties of the control law are discussed.
Biomechanical Analysis of Wrist Loading During Lifting Tasks
Authors: Chou P. H. , Chou Y. L. , Wei H. C. , Ho C. S. , Jiang S.S. 
Published: May 2011

ABSTRACTThis study develops a kinematic/kinetic model to evaluate the effect of different handle angles on wrist loading during lifting task. An imaged-based motion analysis system is used to study the movement pattern, force and moment of the wrist joint among nine different handle angles. Six CCD cameras were used to record 3-D trajectories of limb-mounted markers based on the laboratory coordination system as defined by an 8-marker cube. Euler angles are used to describe the orientation of a distal segment reference frame relative to a proximal segment reference frame. Each segment of the upper extremities is regarded as a uniform rigid body with six degrees of freedom. The resultant loading of the wrist joints was determined using an inverse dynamic procedure.This study indicates that tool handles can be designed or selected to reduce manual loading and the potential for injury during tool use. The mean curve of joint force and moment provided consultations and understandings of the wrist loading during lifting task. In this study, handles that kept the wrist joints in a dorsiflexed and radial deviated position, showed significant reduction in stresses around the surrounding soft tissue.
A Modified Gaussian Integration Scheme in Element Free Method
Authors: Sheng Jopan , Wang Chung-Yue , Shen Kuo-Jui 
Published: May 2011

ABSTRACTIn this paper, a modified numerical integration scheme is presented that improves the accuracy of the numerical integration of the Galerkin weak form, within the integration cells of the analyzed domain in the element-free methods. A geometrical interpretation of the Gaussian quadrature rule is introduced to map the effective weighting territory of each quadrature point in an integration cell. Then, the conventional quadrature rule is extended to cover the overlapping area between the weighting territory of each quadrature point and the physical domain. This modified numerical integration scheme can lessen the errors due to misalignment between the integration cell and the boundary or interface of the physical domain. Some numerical examples illustrate that this newly proposed integration scheme for element-free methods does effectively improve the accuracy when solving solid mechanics problems.
Fluid Flow and Heat Transfer in Duct Fan Flows with Top-Wall Rectangular-Wing Turbulators
Authors: Chen T. Y. , Chen Y. H. 
Published: May 2011

ABSTRACTFluid flow and heat transfer in duct fan flows with a 90° rectangular-wing turbulator, mounted on the top duct wall, were experimentally studied and compared with the bottom-wall turbulator results. Threecomponent velocities were measured to characterize the flow structures and to obtain near-wall flow parameters. Temperatures on heat transfer surfaces were measured to obtain Nusselt number distributions. Results show that the turbulator has the effect to increase the near-wall axial mean velocity, axial vorticity and turbulent kinetic energy, and, consequently, augment the heat transfer. The axial mean velocity and axial vorticity play an influential role on the heat transfer distributions for the flows across the top-wall and bottom-wall turbulators, respectively.
Heat and Mass Transfer for Electrical Conducting Mixed Convection with Radiation Effect for Viscoelastic Fluid Past a Stretching Sheet
Authors: Hsiao K.-L. 
Published: May 2011

ABSTRACTIn this study, an analysis has been performed for heat and mass transfer of a steady laminar boundarylayer flow of an electrically conducting fluid with radiation effect of second grade subject to suction and to a transverse uniform magnetic field past a stretching sheet. Parameters Gr, Gc, Nr, M, Sc represent the dominance of the buoyant effect, radiative effect, magnetic effect and mass transfer effect which have presented in governing equations, respectively. The similar transformation and the finite-difference method have been used to analyze the present problem.
Near-Tip Field and the Associated Path-Independent Integrals for Anisotropic Composite Wedges
Authors: Wu Kuang-Chong 
Published: May 2011

ABSTRACTThe asymptotic fields in an elastic anisotropic composite wedge are considered for a wide range of boundary conditions. It is shown that the eigenfunctions for the near-field and far-field are dual as they are generated by the same set of eigenvalues in general. If the boundary conditions on the wedge faces are the same, an additional eigenfunction may appear in the far-field. Moreover the dual eigenfunctions are used to derive path-independent integrals that relate the near-field to the far-field.
Manipulating Tumble and Swirl Flows in Cylinder of a Motored Four-Valve Engine by Inlet Deflection Valve
Authors: Huang R. F. , Yu J. H. , Yeh C.-N. 
Published: May 2011

AbstractEffects of the inlet-stream deflection on the temporal and spatial evolution processes of the in-cylinder flow structures (tumble/swirl) and turbulence intensities in the symmetry and diametral planes of a motored four-valve, four-stroke engine are diagnosed by using a particle image velocimeter. The inception, establishment, and evolution of the tumbling/swirling vortical flow structures during the intake and compression strokes in the engine cylinder with/without inlet-stream deflection are depicted and compared. Quantitative strengths of the rotating vortical flow motions are presented by dimensionless parameters (tumble and swirl ratios) which can represent the mean angular velocity of the vortices in the target plane. The turbulence intensity is calculated by using the measured time-varying velocity data. The results show that by deflecting the inlet air-stream the tumble and swirl ratios of the in-cylinder flow are appreciably increased by about 0.1 and the turbulence intensity is increased by about 5 ∼ 10%.
Dispersion Control in Nano-Channel Systems Using a Genetic Algorithm
Authors: Kamali R. , Movahed S. 
Published: May 2011

AbstractThere has been a growing interest in developing the miniaturized fluidic devices for transportation, separation and detection of bio-samples. In many of these phenomena electrokinetic effects play an important role. Studies show that in fabricating these devices, if long channels are used, separation efficiency can be improved. In these devices, turns must be induced to integrate a long channel within the small area of a single chip. But these turns can cause a serious dispersion that can result in degraded separation quality. The present study shows that the dispersion in the channel can be reduced by using an optimized distribution for ζ-potential near the turns. A computer code based on the genetic algorithm has been developed to study the dispersion in L-shape and U-shape turns.
A Study on Pushover Analysis of Frame Structure Infilled with Low-Rise Reinforced Concrete Wall
Authors: Lai M. -C. , Sung Y. -C. 
Published: May 2011

AbstractThis paper focused on the pushover analysis of a frame structure infilled with low-rise reinforced concrete (RC) wall. The softening model of concrete as well as the elastoplastic model of reinforcement was considered in the analysis associated with the equilibrium and compatibility conditions. Accordingly, the shear load-deformation relationship of the wall subjected to monotonic lateral load can be analyzed through the proposed analysis procedure. Based on the relationship obtained, we employed a single equivalent structural strut represented by a nonlinear axial member, acting in the diagonal direction of the frame, in simulating the infilled RC wall to simplify the framed wall model. As a result, the sequential pushover analysis of the whole structure could be performed easily and efficiently based on the realistic procedure proposed.To validate the proposed approach, reported results from the cyclic loading tests of fifteen specimens were adopted for the correlation. Based on the correlation, it is found that this study can provide an acceptable result of the pushover analysis and give an insight into progressive failure consequence of the framed wall structure. The proposed procedure simplifying the structural model helps the practical engineers get a higher efficiency while performing seismic evaluation and retrofit design of the high-redundancy frame structure with numerous infilled low-rise RC walls.
Investigation of Effect of Endpoint Constraint on Time-Line Cubic Spline Interpolation
Authors: Tsai T.-L. , Chen J.-Y. 
Published: May 2011

AbstractIn this study, the effects of various endpoint constraints, including the first derivative, natural, quadratic, and not-a-knot endpoint constraints, on the time-line cubic spline interpolation are examined by solving the advection-diffusion equation with constant and variable velocities, and the viscous Burgers equation. The natural endpoint constraint could produce large numerical diffusion. The quadratic endpoint constraint can decrease the numerical diffusion from the natural endpoint constraint, but it could trigger large numerical oscillation. The first derivative endpoint constraint with higher-order central difference approximation has better simulated results than the natural and quadratic endpoint constraints. It can significantly reduce not only the numerical diffusion produced by the natural endpoint constraint, but also the numerical oscillation caused by the quadratic endpoint constraint. The applicability of the time-line cubic spline interpolation together with the not-a-knot endpoint constraint is limited, since the computational instability is caused while the Courant number is greater than unity. Therefore, as far as accuracy and applicability are concerned, the first derivative endpoint constraint with higher-order central difference approximation rather than the commonly used natural endpoint constraint should be a better choice for the time-line cubic spline interpolation.
Ribbing Instability Analysis of Forward Roll Coating
Authors: Lie K. N. , Chiu Y. M. , Jang J. Y. 
Published: May 2011

AbstractThe ribbing instability of forward roll coating is analyzed numerically by linear stability theory. The velocity ratio of two rolls is fixed to be 1/4 for practical surface coating processes. The base flows through the gap between two rolls are solved by use of powerful CFD-RC software package. A numerical program is developed to solve the ribbing instability for the package is not capable of solving the eigenvalue problem of ribbing instability. The effects of the gap between two rolls, flow viscosity, surface tension and average roll velocity on ribbing are investigated. The criterion of ribbing instability is measured in terms of critical capillary number and critical wave number. The results show that the surface coating becomes stable as the gap increases or as the flow viscosity decreases and that the surface coating is more stable to the ribbing of a higher wave number than to the ribbing of a lower wave number. The effect of average roll velocity is not determinant to the ribbing instability. There are optimum and dangerous velocities for each setup of rolling process.
Heat Transfer and Friction Characteristics Optimization with Compound Turbulators in Roughened Ducts
Authors: Kamali R. , Binesh A. R. 
Published: May 2011

AbstractThe use of artificial roughness or turbulence promoters on a surface is an effective technique to enhance the rate of heat transfer of the fluid flowing in a duct. In this study, a computer code has been developed to perform a numerical simulation for optimizing the shape of two-dimensional channel with periodic ribs mounted on the bottom wall to enhance turbulent heat transfer. The Reynolds-Averaged Navier-Stokes analysis is used as a numerical technique and the SST k-(ω) turbulent model with near-wall treatment as a turbulent model. The simulations were performed for two rib shapes, trapezoidal with decreasing height in the flow direction with and without grooves between the ribs. The results are validated by comparing with existing experimental data and semi-empirical correlations. The Reynolds number, pitch-to-rib high ratio and relative groove position are chosen as design variables. The effects of roughness parameters on Nusselt number and friction factor have been discussed and the conditions for the best performance have been determined and presented.
The Consistence Between the Stokes Wave Theory and General Wave Theory
Authors: Liu C.-M. , Hwung H.-H. , Yang R.-Y. 
Published: May 2011

AbstractThe consistence between the Stokes wave theory and general wave theory is examined in this study. As well known, the nonlinear terms of Stokes wave are generated by the self-interaction of first-order wave. On the other side, using the general wave theory one can also obtain the nonlinear solutions according to the interaction of n waves with the same amplitude, frequency and phase. It is found that the inconsistence between these two wave trains arises due to the subharmonic effects included in general wave theory but not considered in the Stokes theory. In conclusion, these two theories are substantially different unless the Bernoulli constants are properly chosen for mathematical equivalence.
Time-Dependent Poiseuille Flows of an Elasto-Viscoplastic Fluid with Hypoplastic Effects
Authors: Fang C. 
Published: May 2011

ABSTRACTAn evolution equation for the Cauchy stress tensor is proposed, taking into account the elastic, viscous and plastic characteristics of complex fluids. Hypoplasticity, in particular, is incorporated to model the plastic features. The model is applied to investigate time-dependent Poiseuille flows between two parallel plates to simulate non-Newtonian behavior of complex rheological fluids. Results show that while different degrees of elastic and viscous features can be indexed by varying the values of the model parameters, hypoplasticity is capable of simulating the plastic characteristics. The fluid tends to be divided into different parallel layers as hypoplastic effects enhance gradually. Applications of the model may be found in geomorphic fluid motions involved granular materials.
Thermo-Acoustic Instability Simulation in Gas Turbine
Authors: Akbari N. , Mehdizadeh N. S. 
Published: May 2011

ABSTRACTThe main aims of this research are, at first, combustion instability study based on equivalence ratio oscillation, and, secondly, investigation various frequency modes of combustion instability, taking combustion chamber geometry into account. Considering the configuration of the simulated combustion chamber, excitation probability of the longitudinal modes is higher than that of transversal modes. The reason of this fact is that the resonance frequency values of the longitudinal modes are less than those of transversal modes. So, the most important frequency mode, during combustion instability, is the first longitudinal mode. In this paper thermo-acoustic instability model is utilized for pre-mixed gas turbines combustion chamber, founded on equivalence ratio oscillation. For this purpose Lieuwen method is developed in order to attain the phase difference between pressure and heat release oscillations. Results concluded from combustion instability simulation for the first longitudinal mode, considering its importance, are compared with experimental data and good agreement is observed.
Nonlinear Aerodynamic Effects on Transonic Flap Buzz, Tail Flutter and Limit-Cycle Oscillations of Two-Dimensional Wing-Flap-Tail Configurations
Authors: Cheng J.-C. 
Published: May 2011

ABSTRACTThe transonic tail flutter and flap buzz under the wing-flap-tail configurations are analyzed utilizing a dynamic grid capability of unstructured Euler solver coupled with an appropriate aeroelastic solver. From the results, the presence of a forewing, either stationary or oscillating, has significant effect on the tail flutter characteristics. In particular, the tail motion may be in resonance with the oscillating wing before the onset of flutter, which is dangerous to the tail structure because of the large amplitude oscillations. Besides, a complicated aerodynamic and aeroelastic interference of the tail have been found due to the unsteady disturbance which is a strong variability of flow structure induced by the buzz of the flap. In the high transonic flow regime, the flap buzz with limit-cycle oscillations does occur, and the influence induced by the tail is not important. The increasing restoring force at the pivot where the flap joints with the wing will reduce the flap oscillations that improves the effect of the flap buzz.
The Rheology of Blood Flow in a Branched Arterial System with Three-Dimensional Model: A Numerical Study
Authors: Hsu C.-H. , Vu H.-H. , Kang Y.-H. 
Published: May 2011

ABSTRACTBlood flow rheology is a very complex phenomenon. Hemodynamics owns Newtonian or non-Newtonian characteristic is still debatable. Recently, studies related to blood tend to classify blood as non-Newtonian fluid. In this research, power law, Casson and Carreau which are being the most popular non-Newtonian models are applied to investigate the hemodynamics variables that influence formation of thrombosis and predict damageability to blood cell. The branched arterial system is simplified as T-junction geometry and the computational fluid dynamics software Fluent 6.2 with finite volume method is utilized to analyze the blood flow rheology in cases of continuous and pulsatile flow. The analysis results are compared with that of Newtonian model and give out very interesting hemodynamics predictions for each model. The size of recirculation zone is different from each model that is observed significantly. The wall shear stress of Carreau model gets the highest value, 14% in case of continuous flow and around 17% in pulsatile case bigger than that of Newtonian model. The results of pulsatile flow show that the Newtonian model is closed to power law model while the Casson model is similar to the Carreau model.
Constructing Poisson and Dissipative Brackets of Mixtures by using Lagrangian-to-Eulerian Transformation
Authors: Chen K.-C. 
Published: May 2011

AbstractThis paper aims to construct the bracket formalism of mixture continua by using the method of Lagrangian- to-Eulerian (LE) transformation. The LE approach first builds up the transformation relations between the Eulerian state variables and the Lagrangian canonical variables, and then transforms the bracket in Lagrangian form to the bracket in Eulerian form. For the conservative part of the bracket formalism, this study systematically generates the noncanonical Poisson brackets of a two-component mixture. For the dissipative part, we deduce the Eulerian-variable-based dissipative brackets for viscous and diffusive mechanisms from their Lagrangian-variable-based counterparts. Finally, the evolution equations of a micromorphic fluid, which can be treated as a multi-component mixture, are derived by constructing its Poisson and dissipative brackets.
Topology Optimization of Elastic-Plastic Structures
Authors: Leu L. J. , Huang C. W. , Chou J. J. 
Published: May 2011

ABSTRACTThe evolutionary structural optimization method is improved and extended to elastic-plastic topology optimization for the first time. An adaptive rejection ratio is proposed to control the number of removal elements without destroying the symmetric pattern in each evolution. Two performance indices suitable for elastic-plastic topology optimization are also proposed and examined. The performance indices can be used to investigate the material efficiency of structures in different evolutionary stages, and to serve as stop criteria in the evolutionary process. Moreover, an interactive special purpose computer analysis and graphics system is developed to visualize the topology in the evolutionary process. Finally, the effects of yield stress, Young's modulus, and the prescribed displacement in an elastic-plastic analysis on the obtained topology are discussed.
Pressure Analysis of Platform Screen Door Subjected to a Moving Train in Mass Rapid Transport Underground Station
Authors: Chun Lin-Jye , Chiang Yuan-Ching , Ting Chun-Chin , Ma Rong-Hua , Chen Sih-Li 
Published: May 2011

AbstractThis paper analyzes the pressure distribution on the platform screen door (PSD) subjected to a moving train running through a station in the tunnel. The advantages of adopting PSD design are to reduce the cooling load and the construction cost in mass rapid transport underground station. However, as the moving train enters or leaves the station, the PSD will face a long-term wind oscillation pressure force. For the safety design, dynamic simulation is requisite for the analysis of pressure force exerted on the PSD. The present study uses the commercial code PHOENICS to simulate dynamically the pressure and velocity distribution on the platform screen door. The results show that the maximum pressure on the platform screen door occurs at 6 m behind the front platform end with the values of 1,457 and 942 Pa, as the train moving speeds are 80km/hr and 65km/hr respectively. It is also indicated that the ratio of the different maximum pressures exerted on the PSD has a linear relationship with the square of train speed ratio for two different train speeds.
Damage Extension Forces and Piezoelectric Fracture Criteria
Authors: Yang X. H. , Dong L. , Chen C. Y. , Wang C. , Hu Y. T. 
Published: May 2011

AbstractDue to external loads, damage extension forces will drive mechanical and electrical damages to evolve in piezoelectric materials from the viewpoint of continuum damage mechanics, so it is important for understanding piezoelectric fracture mechanism and estimating the utilizing life and safety of a piezoelectric device to study the damage extension forces. Based on the static piezoelectric damage constitutive model established in our previously published papers, general expressions of the damage extension forces are given. The finite element method and the iterative procedure are utilized to calculate the extension forces at crack-tips in the samples for the experiments of Park and Sun's, and then the linear and nonlinear fracture criteria are presented. It is revealed from the list of the normalized mean square deviations that the nonlinear criterion is better.