bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reliability-Based Code Calibration for Axial Ultimate Bearing Capacities of Single Bored Piles in Taipei Basin
Authors: Ching J. Y. , Lin H.-D. , Yen M.-T. 
Published: May 2011

ABSTRACTIn Taipei, many pile proof load tests were not conducted to failures but only to a multiple (e.g., 2) of the design load. This leads a difficulty of incomplete information: For these test results, the ultimate bearing capacities of the test piles are unknown. This paper addresses the issue of calibrating resistance factors of piles for the axial ultimate bearing capacities based on the incomplete information from these tests. A simplified probabilistic method is proposed to resolve this issue. A local pile test database of Taipei is presented, and the analysis results show that the inclusion of the incomplete pile load test data helps in calibrating the resistance factors. Moreover, it is found that the calibrated resistance factors for the axial ultimate bearing capacities are consistent to the safety factors that are adopted in the current Taiwan design code. This paper also addresses another important issue for the pile design in Taipei: the end bearing capacity in the sandstone layer is very uncertain. A maximum likelihood method is taken to identify the best estimate for this end bearing capacity. The conclusion of this paper may be useful for reliability-based designs for the axial ultimate bearing capacities of single bored piles in the Taipei region.
A Finite Element Study of the Effect of Contact Forces Between an Implant-Retained Crown and its Adjacent Teeth on Bone Stresses
Authors: Chaichanasiri E. , Nanakorn P. , Tharanon W. , Vander Sloten J. 
Published: May 2011

ABSTRACTMost of finite element (FE) models used to study single tooth dental implants consider only an isolated implant. It is of course more realistic to model also the adjacent teeth of the implant. However, including the adjacent teeth significantly increases the complexity of the model and necessitates the complex contact analysis. The main difference between the FE models with and without the adjacent teeth is that the model without the adjacent teeth cannot capture the effect of the contact forces that are transferred between the implant-retained crown and the adjacent teeth. In this study, the hypothesis that the contact forces are not important is verified by the FE contact analysis. Realistic 3D FE models of a mandible and a single tooth implant with and without adjacent teeth are constructed and analyzed. It is found from the results that the difference between the maximum bone stresses of the two models is very small when various loading directions are considered. The obtained results, therefore, indicate that the effect of contact forces between a dental implant and its adjacent teeth is not significant. Consequently, the adjacent teeth can be excluded from FE models if various loading directions are considered.
A Three-Dimensional Aggregate Generation and Packing Algorithm for Modeling Asphalt Mixture with Graded Aggregates
Authors: Xu R. , Yang X.H. , Yin A.Y. , Yang S.F. , Ye Y. 
Published: May 2011

AbstractA three-dimensional aggregate generation and packing algorithm applicable for modeling asphalt mixture with high content of graded aggregates is presented in this paper. In the algorithm, arbitrary-shaped polyhedra are used to model aggregates, so that the effect of aggregate shape on the mechanical performance of asphalt mixture can be considered. The algorithm consists of two steps: Aggregate generation and packing. Polyhedra are created by extending triangular fundaments and treated as visualized aggregates after passing through convex control and sharpness judgment. After that, graded aggregates are taken out from the aggregate base and randomly packed in a given cylindrical or cubical region one by one equiprobably. Overlapping between nearby aggregates is avoided by the help of Boolean partition operation in ANSYS. Finally, some asphalt mixture samples with a given gradation are modeled as examples, and their effective elastic properties and creep behaviors under uniaxial compression are simulated.
Magnetic Fields Generated by a Mechanical Singularity in a Magnetized Anisotropic Half Plane
Authors: Yeh C.-S. , Ren C.-W. 
Published: May 2011

AbstractThe induced magnetic fields generated by a line mechanical singularity in a magnetized anisotropic half plane are considered in this paper. The linear theory for a soft ferromagnetic elastic with multidomain structure, which has been developed by Pao and Yeh [1] is adopted to investigate this problem. By applying the Fourier transform technique, the exact solutions for the generated magnetic inductions due to various mechanical singularities such as single force, a dipole, single couple and dislocation are obtained in a closed form. The distributions of the generated inductions on the surface are shown graphically.
Adaptive Trajectory Control and Dynamic Friction Compensation for a Flexible-Link Robot
Authors: Erfanian Vahid , Kabganian Mansour 
Published: May 2011

AbstractFriction compensation techniques are studied for control of a flexible-link robot based on the LuGre friction model. To overcome the problem of uncertain parameters in the friction model, adaptive control schemes are used for two different types of parametric uncertainties. A novel dual-observer technique is proposed to estimate the internal state inside the friction model. A distributed-parameter dynamic model is used for the flexible arm to design the controllers. The Lyapunov stability theorem is used to guarantee the global asymptotic stability of the controllers. The performance of position tracking and link vibration attenuation is verified through experimental results. The results also confirm the effectiveness of the proposed friction compensation schemes.
Visualization of Flow Phenomena for Confined Circular Jet Impingement
Authors: Hsieh Shou-Shing , Huang Jung-Tai , Tsai Huang-Hsiu 
Published: May 2011

ABSTRACTFlow visualization was made for water to broaden our fundamental understanding of the physical process of the confined circular jet impingement. Transition (with laminar wall jet) and turbulent regimes are identified. A correlation of boundary layer thickness was developed in terms of relevant parameters.
Measurements of Fractal Properties of Premixed Turbulent Flames and Their Relation to Turbulent Burning Velocities
Authors: Yang S. I. , Shy S. S. 
Published: May 2011

ABSTRACTThe fractal properties of premixed transient flames propagating downwards through a near-isotropic turbulent flow field in a fan-stirred cruciform burner were investigated. The long vertical section of the cruciform burner was used to provide a downward propagating premixed flame at 1 atm. The large horizontal vessel equipped with a pair of counter-rotating fans and perforated plates at each end was used to generate near-isotropic turbulence. Turbulent flame front images were obtained using high-speed laser sheet imaging for both methane-air and propane-air mixtures. The nondimensional turbulent intensity (u′/SL), Reynolds number based on the integral length scale, and turbulent Karlovitz number were varied from 1 to 10, from 698 to 6032, and from 0.05 to 1.43, respectively. Hundreds of runs for each experimental condition were carried out to obtain sufficient images of these turbulent transient flame fronts just in the central uniform region. These images were then processed to extract fractal dimension, inner and outer cutoffs using both the circle and the caliper methods. It was found that the mean fractal dimension is only 2.18, nearly independent of u′/SL, in support of recent Bunsen-flame results found by Gülder and his co-workers. This contradicts the findings of many previous studies in which the fractal dimension may approach asymptotically to a value of 2.33 when u′/SL > 3. The inner (εi) and outer (ε0) cutoffs are found to be nearly constant for all flames studied, where ε0 is an order of magnitude greater than εi and it is smaller than the integral length scale of unreacted turbulence. Finally, the present fractal characteristics cannot predict turbulent burning velocities correctly when the available fractal closure model was used, indicating a limit of the fractal analysis on prediction of turbulent burning velocities.
Inversion of Residual Stress
Authors: Kuo M. K. , Lee H. T. 
Published: May 2011

ABSTRACTA technique for inverting residual stress based on a theory of acoustoelasticity is presented. A general incremental constitutive relation is first derived for a pre-stressed material subjected to an additional infinitesimal elastic deformation. The theory is then employed on using ultrasonic means to evaluate residual stresses of residually stressed materials. The residual stresses are assumed to be homogeneous in materials as usual. The only major assumption in this formulation is that the additional deformations caused by ultrasonic evaluating process are infinitesimal and elastic. No assumption on the origin of residual stresses is needed, nor the assumption on the possible existence of “natural state” of the materials. Successful inversion of residual stresses are demonstrated through a preliminary numerical experiment.
Gas Evolution in Rotating Electrochemical Cells Under Reduced and Normal Gravity Conditions
Authors: Weng Fang-Bor , Su Ay , Kamotani Yasuhiro , Ostrach Simon 
Published: May 2011

AbstractElectrochemical experiments in microgravity are essential for the optimum design of advanced life support systems and power storage systems in space. In the absence of gravity, the evolved gas bubbles will clog the electrode and slow the reaction. Here, a rotating cell concept is introduced as a plan for improving mass transfer and bubble removal in a microgravity environment. A primary experimental study of bubble behavior in rotating water electrolysis cells has been done in reduced gravity through KC-135 parabolic flight. The results show that the cell resistance decreases with increasing rotation rate. Without rotation, the bubbles stick on the electrode surface during reduced gravity period, thus, the cell efficiency degrades. Mass transfer enhanced by bubble generation is investigated in ground-based work at high rotation rate of test cells, so that gravitational effects are minimized.
Refining Strategy of the Supersonic Turbulent Flow Over a Backward-Facing Step
Authors: Yang Shih-Ying 
Published: May 2011

ABSTRACTA modified error indicator is developed to study the supersonic turbulent flow over a backward-facing step. In the Cartesian coordinate system, the unsteady Navier-Stokes equations with a low-Reynolds-number k−ε turbulence model are solved. The modified error indicator, in which the unified magnitude of substantial derivative of pressure and unified magnitude of substantial derivative of weighted vorticity magnitude are incorporated, is applied to treat the mesh refining. To assess the present approach, the transonic turbulent flow around an NACA 0012 airfoil is performed. Based on the comparison with the experimental data, the accuracy of the present approach is confirmed. According to the high-resolutional result on the adaptive mesh, the structure of backstep corner vortex, expansion wave and oblique shock wave is distinctly captured.
Nonlinear Finite Element 2D Analysis for RC Beams Strengthened by Epoxy Bonded Steel Plates
Authors: Lin Wen-Shan , Kao Chen-Chang 
Published: May 2011

ABSTRACTThis paper presents the nonlinear finite element modeling of the global behavior for RC beam strengthened by externally epoxy bonded steel plates up to failure. In addition to the consideration of nonlinear behavior and cracking of concrete, the model involves interface element to capture not only the shear and normal stress concentration at the plate curtailment, but also the separation due to the exceeded peak shear and normal stress. The internal steel bar using truss element and the external steel plate using deformation theory of plastic have been confirmed by compare finite element solution with plastic theory. The proposed finite element solutions result in close correlation with experimental data available for RC beams strengthened by epoxy bonded steel plates with different thickness.
Measurement of Acoustoelastic Effect of Surface Wave with an Improved Acoustic Transducer
Authors: Lee Yung-Chun , Kuo Shi Hoa 
Published: May 2011

ABSTRACTA new acoustic transducer and measurement method have been developed for precise measurements of surface wave velocity. This technique is used to investigate the acoustoelastic effect of surface waves in polymethylmethacrylate (PMMA). The transducer utilizes two miniature conical PZT elements for surface wave transmitter and receiver, and hence can be viewed as a point-source/point-receiver (PS/PR) surface wave transducer. Surface waves are excited and detected with the PZT elements and the surface wave velocity can be accurately determined over a small measurement area. Improvement has been made so that the transducer can be used for both conductive and non-conductive materials. The transducer is then applied to measure the acoustoelastic effect of surface wave in a PMMA specimen. The acoustoelastic coefficients are experimental determined.
Deformation Kinetics of Steady Creep in Sn/Pb Solder Alloys With Applications
Authors: Lee C. F. , Chang M. K. , Chung W. K. 
Published: May 2011

AbstractIn this paper, a constitutive equation of steady creep rates:is derived based on a liaison of the theory of irreversible thermodynamics of continuous media with internal state variables (ISV); and the deformation kinetics. In steady creep, only one ISV is used, whose evolution equation is derived by the concepts of deformation kinetics, in which micromotions are generated by a group of atoms climbing over a tilted potential barrier of the highest height ε0.Applications of the constitutive equation in the cases of some Sn/Pb solder alloys-63Sn/37Pb, 60Sn/40Pb and 97.5Pb/2.5Sn under shear creep tests; and 98Pb/2Sn under tensile creep tests, show that the theoretical results can describe the experimental data quite well. These results pave the way for future research in the comparisons of creep resistance among solders with various Sn/Pb compositions and in the generalization of three-dimensional constitutive equation.
Fundamentals of a Vector Form Intrinsic Finite Element: Part II. Plane Solid Elements
Authors: Ting Edward C. , Shih Chiang , Wang Yeon-Kang 
Published: May 2011

AbstractIn the second article of the series, the vector form intrinsic finite element is extended to formulate plane solid elements, a three-node triangular element and a four-node isoparametric element. Also, conceptual differences of the intrinsic element and traditional element based on variational formulation are discussed.
Fundamentals of a Vector Form Intrinsic Finite Element: Part III. Convected Material Frame and Examples
Authors: Shih Chiang , Wang Yeon-Kang , Ting Edward C. 
Published: May 2011

AbstractIn the third article of the series, a convected material frame is used to develop an incremental analysis procedure to calculate motions with large deformation and large displacement. Five numerical examples are given. The first three illustrate some numerical problems in explicit finite element that are resolved in the present approach. The other two demonstrate the stability and convergence of the method.
Analytical Solutions for Crack Tip Plastic Zone Shape Using the Von Mises and Tresca Yield Criteria: Effects of Crack Mode and Stress Condition
Authors: Jing P. H. , Khraishi T. 
Published: May 2011

AbstractAnalytical closed-form solutions for the crack tip plastic zone shape have been derived for a semi-infinite crack in an isotropic elastic-perfectly plastic solid under both plane stress and plane strain conditions. Two yield criteria have been applied: the Von Mises and Tresca yield criteria. The solutions have been developed for crack modes I and III (mode II has been published previously). The results, which favorably compare to a limited number of existing experimental and analytical findings, indicate that the Tresca zone is larger in size than the Von Mises zone. Moreover, an interesting observation is that both zones are generally much larger than the ones predicted by classical Irwin and Dugdale-Barenblatt solutions.
Theoretical Prediction of Fiber Coupling for Ellipsoidal Microlens
Authors: Chao C.-K. , Hu J.-Y. , Hung S.-Y. , Yang H. H. 
Published: May 2011

AbstractA theoretical approach for an optical lens tip on a single-mode fiber end to improve power coupling from laser diode is presented in this work. The lens shape considered here is an ellipsoid. Based on scalar diffraction and Gaussian mode shapes for the laser and fiber fields, a theoretical model is developed to predict the coupling performance of this microlens. Theoretically, both a high coupling efficiency up to 77% and a large alignment tolerance for 10% off-peak are achieved. The proposed method facilitates mass production to achieve a high-yield and high-coupling efficiency that is suitable to be used in the commercial fiber transmission industry.
Dynamic Analysis and Critical Speed of Pressurized Rotating Composite Laminated Conical Shells Using Generalized Differential Quadrature Method
Authors: Ghayour M. , Ziaei Rad S. , Talebitooti R. , Talebitooti M. 
Published: May 2011

AbstractFree vibration analysis of rotating composite laminated conical shells with different boundary conditions using the generalized differential quadrature method (GDQM), is investigated. Equations of motion are derived based on Love's first approximation theory by taking the effects of initial hoop tension and the centrifugal and Coriolis acceleration due to rotation and initial uniform pressure load into account. Then, the equations of motion as well as the boundary condition equations are transformed into a set of algebraic equation applying the GDQM. The results are obtained for the frequency characteristics of different orthotropic parameters, rotating velocities, cone angles and boundary conditions. The presented results are compared with those available in the literature and good agreements are achieved.
Response of a Maglev Vehicle Moving on a Two-Span Flexible Guideway
Authors: Yau J. D. 
Published: May 2011

AbstractThis paper is intended to present a preliminary framework for dynamic interaction analysis of a maglev (magnetically levitated) vehicle running on a two-span guideway using a comprehensive iterative approach. A maglev vehicle with electrodynamic suspension (EDS) system is simplified as a two degrees-of-freedom (2-DOF) maglev oscillator tuned by a PID (Proportional-Integral-Derivative) controller. The guideway is modeled as a two-span continuous beam with uniform section. Two sets of equations of motion are written, with the first set for the guideway and the second set for the maglev oscillator traveling on the guideway through a motion-dependent magnetic force. To achieve the stable levitation gap for a maglev vehicle moving on a flexible guideway, Ziegler-Nicholas (Z-N) tuning rules are used to determine the tuning parameters of the PID controller. Numerical simulations demonstrate that the levitation gap affects the dynamic response of the maglev vehicle while little influence on the guideway response since the inertial force of the moving maglev vehicle is much lower than its static load.
Analysis of the Concentric Distraction and Distraction Loss of the Bridged Elbow by a Dynamic Fixator
Authors: Shih K.-S. , Lee W.-S. , Tseng C.-S. , Lu T.-W. , Hou S.-M. , Lin S.-C. 
Published: May 2011

AbstractThe mechanisms of concentric distraction and distraction loss within the elbow-fixator-pin construct remains unclear. Furthermore, the literature reports are inconsistent regarding the correct distraction distance between the articulating surfaces of a bridged elbow. This study investigated the mechanism of the distraction loss in terms of the relevant fixator design and elbow angle. Four elbow joints flexed at 90°, 120°, 150°, and 180° were developed in this study. The contribution of each humeral and ulnar distractor to the concentric distraction at the elbow center was evaluated by the finite-element method. The distraction loss within the elbow-fixator-pin construct was studied along the specific load-transferring paths on both elbow sides. Among four elbow models, both concentric and eccentric distractions simultaneously occur at the elbow center. The distraction loss always exists in the joint distraction of the bridged elbow. Comparatively, the 120° elbow model showed the more effectively concentric distraction. For the 180° elbow model, the distraction loss was the highest. This distraction loss was mainly attributed to the lateral deflection of the fixing pins and the vectorial transformation of the distracted length of the distractors. The lateral deflection of the fixing pins is a function of the stiffness of both pins and periarticular tissues. The spatial relationship of the elbow anatomy, elbow angle, and fixator frame plays a significant role in the vectorial transformation of the effective distraction between the elbow articulating surfaces.
Effects of Stacking Sequence on Nonlinear Hydroelastic Behavior of Composite Propeller Blade
Authors: Lin H. J. , Lai W. M. , Kuo Y. M. 
Published: May 2011

AbstractA coupled structural and fluid flow analysis was performed to assess the hydroelastic behavior of a composite marine propeller. The finite element method and lifting surface theory were applied in the structural and fluid analyses, respectively. A coupled equation derived from the Bernoulli equation and the hydrostatic pressure in terms of the blade deflection and strength of the vortex was solved by Newton-Raphson procedure. A MAU 3–60 propeller was analyzed with different stacking sequences of composite layup. The hydroelastic behaviors of the propeller with balanced and unbalanced stacking sequences were investigated and discussed. The unbalanced Stacking sequences were shown to influence the performance of the composite propeller, especially in the region in which the advanced coefficient is low.
Magnetoelectroelastic Interaction between a Generalized Screw Dislocation and Multiple Circular Inclusions
Authors: Shen M. H. , Chen F.M. , Hung S. Y. , Chen S.N. 
Published: May 2011

AbstractIn this paper, the interaction of a generalized screw dislocation with multiple circular inclusions perfectly bonded to an unbounded matrix under remote magnetoelectromechanical loadings is dealt with. The analytical solutions of electric field, magnetic field and displacement field either in the inclusions or the matrix are obtained by use of the complex variable method. The image force acting on the magnetoelectric screw dislocation is calculated by using the generalized Peach-Koehler formula. Finally, the influence of material combinations on the image force is examined for several practical examples. The obtained solutions can be used as Green's functions for the analysis of the corresponding magnetoelectric crack problem.