bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Postbuckling Analysis of 3D Braided Composite Cylindrical Shells
Authors: Li Z.-M. , Yang D.-Q. 
Published: May 2011

AbstractThermal postbuckling analysis is presented for 3D braided composite cylindrical shell of finite length subjected to a uniform temperature rise. Based on a micro-macro-mechanical model, a 3D braided composite may be as a cell system and the geometry of each cell is deeply dependent on its position in the cross-section of the cylindrical shell. The material properties of epoxy are expressed as a linear function of temperature. The governing equations are based on Reddy's higher order shear deformation shell theory with a von Kármán-Donnell-type of kinematic nonlinearity and including thermal effects. A singular perturbation technique is employed to determine the buckling temperatures and postbuckling behaviors of 3D braided composite cylindrical shells. The numerical illustrations concern the postbuckling behavior of perfect and imperfect, braided composite cylindrical shells with different values of geometric parameter and of fiber volume fraction. The results show that the shell has lower buckling temperatures and postbuckling equilibrium paths when the temperature-dependent properties are taken into account. The results reveal that the fiber volume fraction, braiding angle and the shell geometric parameter have a significant effect on the thermal buckling and postbuckling behavior of braided composite cylindrical shells.
Derivation of Cyclicp-yCurves From Instrumented Dynamic Lateral Load Tests
Authors: Lin S.-S. , Lai C.-H. , Chen C.-H. , Ueng T.-S. 
Published: May 2011

AbstractIn this paper, an efficient method is proposed to derive cyclicp-ycurves from either push-over or shaking table test results. The Fourier series function, satisfying the boundary conditions of a pile, is used to represent deflection behavior of the pile-soil system at each instant of time during loading interval. In order to obtain soil reaction along the pile shaft, convergence of the series after differentiation is guaranteed by applying the Cesaro sum technique. Results of four push-over tests and two other shaking table test results, conducted at the National Center for Research on Earthquake Engineering in Taiwan, are then used to verify the feasibility of the proposed method.
Evolution Instability and Growth Competition Study on Langmuir Circulation
Authors: Yang R.-Y. , Liu C.-M. , Hwung H.-H. , Kong C.-H. 
Published: May 2011

AbstractLangmuir circulation that has been disturbed by a perturbed source in a horizontal Couette flow with a vertical density gradient (i.e., the effective Rayleigh numberR) and horizontal Couette flow is investigated. The evolution of instability developing in the presence of a vertical density gradient influenced by the disturbance at various depths and the horizontal Couette flow is considered near the onset of convection under a moderate rate of shear. We use velocity as the basic variable and solve the pressure Poisson equation in terms of the associated Green function. Growth competition between the longitudinal vortices (Lv) and the transverse vortices (Tv), whose axes are respectively in the direction parallel to and perpendicular to the Couette flow, is investigated by the weakly nonlinear analysis of coupled-mode equations. The results show that the Tv mode is characterized in some range of the effective Rayleigh number, and that the stability is dominated by the Lv mode in the system.
Kinematic Study of an Innovative Dynamic Bridging Wrist External Fixator with Arthrodiatasis
Authors: Shih K.-S. , Lin S.-C. , Liu Y.-H. , Chang T.-H. , Hou S.-M. , Lu T.-W. 
Published: May 2011

AbstractExternal wrist fixators have been widely used to stabilize distal radial fractures. Ideally an external fixator would create a stable environment for the fracture to heal while allowing proper mobility for the wrist. However, this has been a great challenge to the designers.The current study aimed to develop a bridging wrist external fixator that is easy for surgeons to create a stable environment for the fracture to heal while allowing proper wrist mobility for rehabilitative purposes. The kinematic geometry of the wrist-fixator system was described using loop equations defined by homogeneous transformation matrices (HTM) of the joints involved, and was evaluated numerically for a set of system parameters that are determined by surgeons during surgery. The results were validated with geometric models and computer simulation. The contributions of individual clinical parameters to the kinematic geometry of the wrist-fixator system were also analyzed using the Taguchi method.Adequate pin placement and hinge alignment function were found to be critical for the postoperative bridged wrist motion. The results of the current study will be helpful for surgeons to perform fixation using the new wrist fixator and for designers to design new fixators in the future.
Biomechanical Role of the Locomotor System in Controlling Body Center of Mass Motion in Older Adults During Obstructed Gait
Authors: Wang T.-M. , Chen H.-L. , Hsu W.-C. , Liu M.-W. , Lu T.-W. 
Published: May 2011

AbstractFifteen young and fifteen older healthy adults walked and crossed obstacles of three different heights while kinematic data and ground reaction forces were acquired to calculate the three-dimensional motion of the centre of mass (COM) and lower limb joint moments. The older group had greater normalized jerk score of the COM. When the leading limb was crossing, the older group kept the COM more posterior and on the trailing stance limb for longer with increased knee extensor crossing moments and thus decreased anterioposterior COM deceleration. When the trailing limb was crossing, the older group decreased vertical COM deceleration through increased hip extensor crossing moments. The older group maintained the same COM motion as the young in the frontal plane with greater hip and knee abductor crossing moments. The older group exhibited significant kinetic changes in their locomotor system with increased muscular demand, leading to a more jerky motion of the body COM. However, these changes helped to maintain the frontal COM motion and to achieve a sagittal COM motion pattern which is thought to be helpful for a safe and successful obstacle-crossing. Failure to meet the kinetic demands in the elderly may increase the risk of falls during obstacle-crossing.
Control of Body's Center of Mass Motion During Level Walking and Obstacle-Crossing in Older Patients with Knee Osteoarthritis
Authors: Hsu W.-C. , Wang T.-M. , Liu M.-W. , Chang C.-F. , Chen H.-L. , Lu T.-W. 
Published: May 2011

AbstractKnee osteoarthritis (OA) has been reported to affect the performance of ambulation, including unobstructed and obstructed gait. An increased risk of falling in patients with knee OA during obstaclecrossing, as opposed to unobstructed level walking, may be explained by the difference in the control of the body's center of mass (COM) with respect to the center of pressure (COP) while trying to ensure sufficient foot clearance. The purpose of the study was to investigate the dynamic stability in patients with knee OA during level walking and obstacle-crossing. The COM-COP inclination angles and angular velocities, as well as temporal-spatial variables, from eleven patients with bilateral knee OA and eleven normal controls were obtained during level walking and obstacle-crossing using a three-dimensional motion analysis system and forceplates. Demands in the control of the COM relative to the COP were found to be greater during obstacle-crossing in both subject groups. While less stable COM control was found around the end stage of double stance phase during obstacle-crossing when compared to level walking, patients with knee OA successfully acquired strategies in the sagittal plane to maintain close-tonormal stable COM control with normal toe clearances during both level walking and obstacle-crossing. They achieved stable transitions from single limb stance (SLS) to double limb stance (DLS) through a reduced anterior inclination angle and from DLS to SLS through increased anterior angular velocity. It is suggested that assessment of the ability to control dynamic stability in patients with knee OA should consider both the positions and velocities of the COM and COP.
A Finite Element Model for Composite Beams with Piezoelectric Layers Using a Sinus Model
Authors: Beheshti-Aval S.B. , Lezgy-Nazargah M. 
Published: May 2011

AbstractIn this study, finite element modeling of composite beams with distributed piezoelectric sensors and actuators which is based upon a coupled electromechanical model has been considered. For modeling of mechanical displacement through the thickness, a sinus model that satisfies continuity conditions of transverse shear stresses and the boundary conditions on the upper and lower surfaces of the beam has been employed. In the presented model, the number of unknowns is not dependent on the number of layers. The variation of electric potential in each piezoelectric layer has been modeled using layer-wise theory. By applying the virtual work principle (VWP), a formulation has been developed for a two-nodded Hermitian-2(n +1) layer-wise nodded element for a n-layered beam. The VWP leads to a derivation that could include dynamic analysis. However, in this study only static problems have been considered. Comparison of results obtained from this formulation with available works in the literature, demonstrates efficiency of proposed model in analysis of laminated beams under mechanical and electrical loadings.
Applicability of Reichardt's Hypothesis to the Prediction of Velocity Field of Multiple Parallel Plane Jets
Authors: Nasr A. , Lai J. 
Published: May 2011

AbstractIn this paper the velocity distribution for multiple parallel plane jets based on the superposition of Reichardt's solution for single free jet is derived. The extend of the applicability of Reichardt's hypothesis to prediction of multiple parallel plane jets is examined. Both ventilated and unventilated two parallel plane jets data published in the literature and obtained for this study were used for comparisons with the theoretical results obtained from Reichardt's hypothesis. LDA measurements of mean streamwise velocities and turbulence characteristics of an array of 5 parallel plane jets were also made in order to establish the conditions under which this heuristic approach is valid. Results show that provided the pressure gradient in the lateral direction is small and hence the deflection of the individual jet center line is small, there is a good agreement between experimental results and predictions based on Reichardt's hypothesis for multiple parallel plane jets.
Convective Heat Transfer of the Flow through a Rotating Circular Straight Pipe
Authors: Lei U. , Yang Arthur C. Y. 
Published: May 2011

ABSTRACTLaminar heat transfer for large ranges of Reynolds numbers, rotational Reynolds numbers, and Prandtl numbers are studied numerically for incompressible fully developed flow in a circular straight pipe, which is rotating constantly about an axis perpendicular to its own axis under the constant wall temperature gradient condition. There exist four types of local Nusselt number distributions associated with the four different flow regimes for different parameters depending on the relative importance of different forces. Correlations of the averaged Nusselt number are also provided. When the Prandtl number is sufficiently large, the temperature distribution in the core is determined essentially by the secondary flow. Scaling analyses are provided for understanding the essential physics of the problem.
Heat Conduction in a Cylindrically Anisotropic Tube of a Functionally Graded Material
Authors: Tarn Jiann-Quo , Wang Yung-Ming 
Published: May 2011

AbstractA state space approach to heat conduction in a cylindrically anisotropic circular tube of functionally graded materials (FGM) is presented. A power-law type of the radial inhomogeneity for the FGM is considered. By means of eigenfunction expansion and matrix algebra, analytic solutions for transient and steady-state heat conduction in the FGM tube under general thermal boundary conditions are derived.
The Pseudo Dynamic Test of RC Bridge Columns Analyzed Through the Hilbert-Huang Transform
Authors: Li Y.-F. , Chang S.-Y. , Tzeng W.-C. , Huang K. 
Published: May 2011

AbstractIn this paper, the analysis of the responses of the pseudo dynamic test of two rectangular reinforced concrete (RC) bridge columns using the Hilbert-Huang transform (HHT) is introduced. Firstly, two 40%-scaled rectangular RC bridge columns are subjected to the pseudo dynamic test. The input of the pseudo dynamic test is set as the near-fault ground accelerations of the Chi-Chi Earthquake, which happened in 1999 in central Taiwan. After damage occurs to the bridge columns, we use non-shrinkage mortar to repair the columns, and then use 3 layers of CFRP to rehabilitate their plastic zone. The repaired bridge columns are again tested. Then we use the HHT to analyze the responses of the as-built and repaired bridge columns. The merit of applying the HHT to the responses of bridge columns is that it can transfer the displacement-time responses into instantaneous frequency responses, while the spectra are a function of both frequency and time. We can observe from the Hilbert spectra of the bridge columns that, at the instant when the frequency changes, the structural behavior changes from elastic to inelastic. The HHT can therefore be used to obtain the instantaneous natural frequencies of the bridge columns and to understand the relationship between the frequency changes and stiffness condition of the bridge columns.
On the Design of An Innovative Latch Mechanism in SMIFed Wafer Containers
Authors: Pai Wei-Ming , Chen Dar-Zen , Lee Jyh-Jone , Ho Chi-Zer 
Published: May 2011

AbstractThis paper presents the design process for an innovative latch mechanism in a standard mechanical interfaced (SMIFed) wafer container, in which the manufactured integrated circuits are stored. An innovative latch mechanism is proposed and applied to the wafer container, such that the container door can be latched and air-tightly sealed during storage or transportation. The design process is divided into two stages. In the first stage, an output slot-cam is designed in order to generate decoupled fine motions of the output link. The issue is formulated as an optimization problem where the output link dimensions are optimized to minimize the resultant pin forces subject to an adequate transmission angle. In the second stage, the input slot-cam is designed to achieve that kinetic energy of the elastic gasket on the container lid is absorbed at a uniform rate. Finally, a numerical example and computer simulations are given to demonstrate the results of design process. It is believed that this work could aid in enhancing the performance and reliability of the latch mechanism in the SMIF environment.
Depth Measurement of Surface-Breaking Cracks Using Point-Source/Point-Receiver Acoustic Transducer
Authors: Lee Yung-Chun , Kuo Shi Hoa 
Published: May 2011

ABSTRACTA newly developed point-source/point-receiver (PS/PR) acoustic transducer is used for measuring the depth of surface-breaking cracks. The transducer consists of two miniature conical PZT elements which form a transmitter/receiver pair for generating and detecting surface waves. A tone-burst measurement system operates the PS/PR transducer at a fixed frequency. When a surface-breaking crack is present in between the transmitter and receiver, the change in time-of-flight of surface wave propagation caused by the crack is measured and used to estimate the crack depth. To verify the feasibility of this method, machined slots on a carbon steel sample are tested by the PS/PR transducer for crack depth determination. Good experimental results are obtained. Future applications and improvements on the PS/PR transducer system are addressed.
Fundamentals of a Vector Form Intrinsic Finite Element: Part I. Basic Procedure and A Plane Frame Element
Authors: Ting Edward C. , Shih Chiang , Wang Yeon-Kang 
Published: May 2011

AbstractIn a series of three articles, fundamentals of a vector form intrinsic finite element procedure (VFIFE) are summarized. The procedure is designed to calculate motions of a system of rigid and deformable bodies. The motion may include large rigid body motions and large geometrical changes. Newton's law, or a work principle, for particle is assumed to derive the governing equations of motion. They are obtained by using a set of deformation coordinates for the description of kinematics. A convected material frame approach is proposed to handle very large deformations. Numerical results are calculated by using an explicit algorithm. In the first article, using the plane frame element as an example, basic procedures are described. In the accompanied articles, plane solid elements, convected material frame procedures and numerical results of patch tests are given.
Analytical Solutions of Saint Venant Equations Decomposed in Frequency Domain
Authors: Chung W. H. , Kang Y. L. 
Published: May 2011

AbstractThe Saint Venant equations are often merged into a single equation for being easily solvable. By doing so, the most general form of the single equation is formulated in this study if all terms are preserved. As a result, the generalized model (GM) results and contains several unexpected nonlinear terms that may impose a great limitation on model analyses. In order to identify these redundant terms, this paper discusses the employment of the linearized Saint Venant equations (LSVE) governing subcritical flow in prismatic channels. The LSVE is solved by a new procedure that separates, in the Laplace frequency domain, the governing equation of water depth from that of flow velocity and thus enables us to consider two independent equations rather than two coupled ones. This allows us to obtain analytical solutions in a much easier way. Comparisons of the response functions of LSVE and the linearized generalized model (LGM) show that the two equations provide identical solutions if the redundant terms embedded in LGM are neglected. It then follows that the response function of LGM can be utilized as a replacement for solving the analytical solution of LSVE that is valid for prismatic channels of any shape. Validity of the analytical solution is verified by repeatedly comparing with the corresponding numerical solutions of finite difference method or Crump's algorithm [1], depending on whether the flow domain is finite or semi-infinite. It is clearly demonstrated in this paper that LSVE serves as an excellent substitution for LGM whose variants have been employed for quite a few years.
Thermosolutal Convection in an Inclined Rectangular Enclosure with a Partition
Authors: Wang L. W. , Kung Y. C. , Wu C. Y. , Kang M. F. , Wang S. L. 
Published: May 2011

AbstractAn experimental study of thermosolutal convection in an inclined rectangular enclosure with a partition is presented in this article. Aspect ratio, partition ratio, and inclination angle were kept constant at Ar =0.5, Ap = 0.25 and φ = 30°, respectively. The convective flow is generated by both inclined temperature and concentration gradients under limiting current condition. Both the thermal and solutal buoyancies, which either cooperated or opposed one another, were induced from the copper plates. The temperature gradient was maintained and controlled using two separate constant temperature baths that circulated heated or cooled water through a heat exchanger. We used copper sulphate-sulfuric acid solution as both the working fluid and the electrolyte. An electrochemical method based on a diffusion-controlled electrode reaction was employed to create the concentration gradient. We used the shadowgraph recording technique to visualize and analyze the flow field phenomenon. Thermal Grashof numbers ranging from 8.16 × 105 to 16.32 × 105 and a solutal Grashof number Grm = 4.36 × 106 were investigated. It is demonstrated that the mass transfer rate increases with the increasing thermal Grashof numbers within our experimental ranges. Multilayer structures are found in the cooperating case or the opposing case.
The Constellation Design of Weather Observation Mission for Gravity-Gradient Stabilized Microsatellites
Authors: Lin C.-H. , Hong Z.-C. , Shieh C.-J. 
Published: May 2011

AbstractThis paper focuses on the design of a weather observation constellation consisting of gravity-gradient stabilized satellites for acquiring weather images of Taiwan on an hourly basis. The CCD imaging system is made up of the imaging module, the image-processing module and the sequencing operation controller. The CCD imaging logic is designed to determine the optimal imaging opportunity according to the orbital data. In order to compare with the existing polar systems and the TUUSAT-1 mission, the Walker Constellation method is also employed to calculate the minimum number of satellites required in a constellation. The calculation results show that the 8/8/5 Walker Constellation can satisfactorily meet the coverage requirements. Compared with the design of constellations which are constituted of the existing polar weather satellites and the passive magnetic stabilized satellites respectively, the present constellation design employs a smaller number of satellites to meet the same coverage requirements.
Influence Functions of a Point Force for Kirchhoff Plates with Rigid Inclusions
Authors: Melnikov Y. A. 
Published: May 2011

AbstractA semi-analytic method is proposed for two problem settings for a Kirchhoff plate containing an absolutely rigid circular inclusion and undergoing a transverse point force. The settings differ by the location (within and out of inclusion) of the force application point. In both cases, the plate's stress-strain state is simulated with a boundary value problem for the biharmonic equation stated over a doubly connected region whose inner contour represents the edge of the inclusion. Boundary conditions imposed on the inner contour bring some parameters which are found via the equations of static equilibrium of the inclusion. A modification of the Kupradze'smethod of functional equationsis proposed for obtaining influence functions of a point force for such plates. Green's functions of the biharmonic equation for appropriately shaped simply connected regions are employed. Numerical differentiation is never required in the computing of stress components and the latter are subsequently found with accuracy level comparable with that attained for the deflection function.
Formulas for Curvature Ductility Design of Doubly Reinforced Concrete Beams
Authors: Chen C. C. , Hsu S. M. 
Published: May 2011

AbstractWith the concrete treated as unconfined, semi-empirical equations for curvature ductility ratios of doubly reinforced beam sections were derived. Based on the resulted semi-empirical equations, design formulas for curvature ductility ratios, which take into account the effect of tension and compression reinforcement ratios and strengths of reinforcement and concrete, are established and calibrated. The proposed design formulas are fairly simple with reasonable accuracy. The proposed design formulas enable the designer to design beam sections for selected ductility ratios, and, consequently, to acquire better control of concrete spalling during major earthquakes. From the aspect of performance based design, the proposed formulas can facilitate beam design for concrete spalling limit state.