bluuebunny/crossref_metadata_2025_split huggingface dataset:
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 twonodded 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.
Elastic Constants of Composite Materials by an Inverse Determination Method Based on A Hybrid Genetic Algorithm
Authors: Hwang S.-F. , Wu J.-C. , Barkanovs Evgeny , Belevicius Rimantas 
Published: May 2011

AbstractA numerical method combining finite element analysis and a hybrid genetic algorithm is proposed to inversely determine the elastic constants from the vibration testing data. As verified from composite material specimens, the repeatability and accuracy of the proposed inverse determination method are confirmed, and it also proves that the concept of effective elastic constants is workable. Moreover, three different sets of assumptions to reduce the five independent elastic constants to four do not make clear difference on the obtained results by the proposed method. In addition, to obtain robust values of the five elastic constants for a transversely isotropic material, it is recommended to use the out-of-plane Poisson's ratio instead of the out-of-plane shear modulus as the fifth one.
Identification of Adhesive Bond in A Multi-Layered Structure Via Sound Insulation Characterestics
Authors: Malakooti S. , Mohammadi N. , Mahjoob M. J. , Mohammadi K. 
Published: May 2011

AbstractIn this paper, adhesive bonds in multi-layered plates are identified based on experimental values of their sound insulation characteristics. An exact model based on two-dimensional elasticity theory is formulated. The problem is a time harmonic plane acoustic progressive wave interaction with an isotropic multi-layered infinite elastic plate with interlaminar bonding imperfections. The T-matrix solution technique, which involves a system global transfer matrix, is formed as the product of individual transfer matrices. This is accomplished by applying continuity of the displacement and stress components at the interfaces of neighboring layers along with the relevant boundary conditions at the left and right interfaces of the plate with the surrounding acoustic fluid (air). The resulting equations are then solved for the unknown plane wave reflection and transmission coefficients. The experimental values of sound transmission loss (TL) are measured by a modified B&K impedance tube. Results are presented for a double-layered (lead-steel) plate while the layers are bonded together with metal glue. The normal and transverse adhesive spring constants of the metal glue are then identified in an inverse manner. The agreement of experiments with the analytical TL values predicted for a new triple-layered plate (based on the identified bond properties) confirms the validity of the method.
Simulation of Entrainment Mass Transfer in Annular Two-Phase Flow Using the Physical Concept
Authors: Baniamerian Z. , Aghanajafi C. 
Published: May 2011

AbstractMost of two-phase heat transfer analysis involve estimation of dry-out phenomenon in order to find whether it takes place and if so, at what location in the tube it will happen. Dry-out phenomenon considerably reduces heat transfer rate and it should be avoided as far as possible. Entrainment highly affects dry-out occurrence chance and location. Therefore a great attention should be paid on simulation of entrainment in order to have a good estimation of heat transfer and to safely design thermal systems.Although there are many models available for simulation of entrainment phenomenon, few are instrumentally employed in heat and fluid flow analyses, since most of those are empirical and limitedly can be applied due to the restricted conditions of experiments. There also are few theoretical approaches in the literature for simulating entrainment phenomenon by applying the physical potential of entrainment but some of those have a considerable deviation from the available empirical models. In the present study a conceptual approach is employed to simulate entrainment. In this regard the most important potential of this phenomenon, known as interfacial waves, are studied and modeled to find how they will lead to entrainment and how much the amount of entrainment is in vertical annular two-phase flows. An entrainment correlation is proposed at the end and will be compared with the available empirical ones for the verification objectives.
Revisit of Two Classical Elasticity Problems by using the Null-Field Boundary Integral Equations
Authors: Chen J. T. , Lee Y. T. , Chou K. H. 
Published: May 2011

AbstractIn this paper, the two classical elasticity problems, Lamé problem and stress concentration factor, are revisited by using the null-field boundary integral equation (BIE). The null-field boundary integral formulation is utilized in conjunction with degenerate kernels and Fourier series. To fully utilize the circular geometry, the fundamental solutions and the boundary densities are expanded by using degenerate kernels and Fourier series, respectively. In the two classical problems of elasticity, the null-field BIE is employed to derive the exact solutions. The Kelvin solution is first separated to degenerate kernel in this paper. After employing the null-field BIE, not only the stress but also the displacement field are obtained at the same time. In a similar way, Lamé problem is solved without any difficulty.
Generation of Harmonics by Non-Breaking Water Waves Over Permeable Submerged Breakwaters
Authors: Ting Chao-Lung , Lin Ming-Chung 
Published: May 2011

ABSTRACTThis work examines the interesting phenomenon of the generation of harmonics by non-breaking waves over permeable submerged obstacles. Nine model geometries, each with six different porosities, from 0.421 to 0.912, were considered to examine the effects of model width, porosity, and submergence depth on harmonic generation. The results revealed coupled effects on harmonic generation. A modified Ursell number was proposed to analyze experimental data. Almost no harmonic generation occurs at a modified Ursell number of less than five and/or a model width to wavelength ratio of over 1.6. After harmonics have been generated, wave profiles become dimpled, and the energy of the fundamental mode is transferred to higher-frequency components. Furthermore, the higher harmonics become more pronounced as the models widen, the depth of submergence becomes shallower, and model porosity declines.
Coefficients of Time and Length Scales of Turbulent Eddies
Authors: Chang Keh-Chin , Jeng Shih-Shiang 
Published: May 2011

ABSTRACTThe turbulence time and length scales representing the energy containing eddies are by Tt= CtTk/ε and ℓt= Ctℓk32/ε, respectively, while the Kolmogorov time and length scales representing the energy dissipative eddies are expressed by Tk= CkT(ν/ε)1/2and ℓk= Ckℓ(ν3/ε)1/4, respectively. The available DNS data for fully developed channel flows with and without wall injection / suction are used to determine the coefficients. It is found that, with the typical values of CtT= Ctℓ= 1 which are usually adopted in the turbulence study, ckT= 2 and Ckℓ= 3. However, this set of coefficients lead to underprediction of the thickness of viscous sublayer. By relaxing the usual assumption of CtT= Ctℓ= 1, a new set of coefficients: CtT= Ctℓ= 0.8, CkT= 4, and Ckℓ= 9 is suggested. Thecalculated with this set of coefficients becomes more physically reasonable.
Qualitative Properties of Frequencies and Modes of Beams Modeled by Discrete Systems
Authors: Wang D. J. , Chou C. S. , Wang Q. S. 
Published: May 2011

ABSTRACTIn this paper, a discrete system model and its equation of motion for beams with arbitrary supports at two ends are established. These supports include elastic, rigid and free supports in translation and rotation directions. Based on theory of oscillatory matrices, a series of qualitative properties of frequencies and modes of this system are derived. The basic properties include: non-zero frequencies are distinct; the ith displacement mode has i - 1 nodes; nodes of ith mode and (i + 1)th mode interlace.Some additional important qualitative properties owned by rotation modes and strain modes are given as well.
Inverse-Ray Imaging of 2D Layered Structures from Seismic Reflection Data
Authors: Wang Tan K. , Tan S. C. 
Published: May 2011

ABSTRACTShooting angle of an inverse ray for imaging 2D multi-layered structures from reflected travel-times is derived in a closed form. By considering the normal incidence of two neighboring rays reflected at interfaces when sources are at the same locations as receivers, the traveling distance and direction of two inverse-rays are determined successively from the lowermost layer to the uppermost layer. This approach is similar to and also confirmed with the Huygens' principle that the equal travel-time along a wave front (perpendicular to the rays) is conserved. The closed-form solution of the inverse rays is further applied to image a complex structure of a ramp-flat fault with eleven layers. The results demonstrate that the inverse-ray imaging from travel-time picks of all layers is superior to that picked by a layer-stripping approach.
Fundamental Singularities in a Two-Fluid Stokes Flow with a Plane Interface
Authors: Yu H. Y. 
Published: May 2011

ABSTRACTA modified image method is presented for obtaining the solutions of the fundamental singularities in the neighborhood of a plane interface between two semi-infinite, immiscible, and incompressible viscous fluids. The fundamental singularities considered are the stokeslet, rotlet, stresslet, stokes-doublet, source, and source-doublet. The Galerkin vector function representation introduced reduces the complexity of the expressions for the solutions. Moreover, the physical meaning of each solution is clearly identified by these new expressions.
Application of Spline Collocation Method in Analysis of Beam and Continuous Beam
Authors: Wu Lai-Yun , Chen Yang-Tzung 
Published: May 2011

ABSTRACTIn this paper, spline collocation method (SCM) is successfully extended to solve the generalized problems of beam structures. The spline functions in SCM are re-formulated by finite difference method in a systematical way that is easily understood by engineers. The manipulation of SCM is further simplified by the introduction of quintic table so that the matrix-vector governing equation can be easily formulated to solve the weighting coefficients. SCM is first examined by the problems of a generalized single-span beam undergoing various types of loadings and boundary conditions, and it is then extended to the problems of continuous beam with multiple spans. By comparing with available analytical results, differential quadrature method (DQM), if any, excellent accuracy in deflection is achieved.
Finite Element Model Verification for the Use of Piezoelectric Sensor in Structural Modal Analysis
Authors: Wang B.-T. , Chen P.-H. , Chen R.-L. 
Published: May 2011

AbstractThis paper presents the theoretical modal analysis for the use of PVDF sensor in structural modal testing via finite element analysis (FEA). A series of rectangular PVDF films are adhered on the surface of cantilever beam as sensors, while the point impact force is applied as the actuator for experimental modal analysis (EMA). Natural frequencies and mode shapes determined from both FEA and EMA are validated. In FEA, the beam structure is modeled by 3D solid elements, and the PVDF films are modeled by 3D coupled field piezoelectric elements. Both modal analysis and harmonic response analysis are performed to obtain the structural modal parameters and frequency response functions, respectively. Results show that both FEA and EMA results agree well. In particular, the PVDF sensor mode shapes, proportional to the slope difference between the two edges of PVDF film, are numerically and experimentally validated by FEA and EMA, respectively. Therefore, the simulation of PVDF films for vibration analysis in FEA can be verified and easily extended to other complex structures that may contain piezoelectric materials.
Topological Flow Structures of Annular Swirling Jets
Authors: Tsai Feng Chin , Huang Rong Fung 
Published: May 2011

AbstractThe effects of blockage and swirl on the macro flow structures of the annular jet past a circular disc are experimentally studied through the time-averaged streamline patterns. In the blockage-effect regime, the flows present multiple modes, single bubble, dual rings, vortex breakdown, and triple rings, in different regimes of blockage ratio and swirl number. The topological models of the flow structures are proposed and discussed according to the measured flow fields to manifest the complex flow structures. The single bubble is a closed recirculation bubble with a stagnation point on the central axis. The dual-ring flow is an open-top recirculsation zone, in which a pair of counter-rotating vortex rings exists in the near wake. The fluids in the dual rings are expelled downstream through a central jet-like swirling flow. A vortex breakdown may occur in the central jet-like swirling flow if the exit swirl number exceeds critical values. When the vortex breakdown interacts with the dual rings, a complex triple-ring flow structure forms. Axial distributions of the local swirl number are presented and discussed. The local swirl number increases with the increase of the exit swirl number and attains the maximum in the dual-ring mode. At large exit swirl numbers where the vortex breakdown occurs, the local swirl number decreases drastically to a low value.
Simulation of Flow Induced Vibrations of Tube Bundle in Cross Flow
Authors: Lin Tsun-Kuo , Yu Ming-Huei 
Published: May 2011

ABSTRACTThe flow-induced vibration of tubes in a rotated triangular array subject to cross flow is simulated numerically. In the study, the flow field around the tube bundle is computed by solving the continuity and Navier-Stokes equations with assumption of constant fluid properties, and the kε-model for turbulent Reynolds stress. With the flow field known, the fluid forces on the tube surfaces can be calculated, and then the displacement of each tube due to the fluid force can be evaluated. Iteration is needed to obtain the dynamic response of the tube structure in the fluid flow. The parameters in the study are inlet velocity of the cross flow and properties of the tube bundle including natural frequency, damping factor, and mass. Based on the tube response, the critical flow conditions of tube vibration are determined for varying mass damping. Once tube vibrations occur, it is shown that the vibrations of the tubes in the second and fourth tube rows are significant as compared to other tubes. The orbits of the tube vibration look like an ellipse with major axis in the cross-stream direction, implying large lift force on the tubes. The dominant frequency in the spectrum of lift coefficients of the tubes is the same as the natural frequency, and the corresponding amplitude is increased with increasing the inlet velocity. The calculated data predicted for the critical reduced velocity agrees well with the data by Kassera and Strohmeier [17].
Rheological Characteristics for Thin Film Elastohydrodynamic Lubrication
Authors: Chu H.-M. , Lee R. T. , Hu S. Y. , Chang Y.-P. 
Published: May 2011

ABSTRACTThis paper uses three lubrication models to explore the differential phenomenon in the status of thin film lubrication (TFL). According to the viscous adsorption theory, the modified Reynolds equation for thin film elastohydrodynamic lubrication (TFEHL) is derived. In this theory, the film thickness between lubricated surfaces is simplified as three fixed layers across the film, and the viscosity and density of the lubricant vary with pressure in each layer. Under certain conditions, such as a rough or concentrated contact of a nominally flat surface, films may be of nanometer scale. The thin film elastohydrodynamic lubrication (EHL) analysis is performed on a surface forces (SF) model which includes van der waals and solvation forces. The results show that the proposed TFEHL model can reasonably calculate the film thickness and the average relative viscosity under thin film EHL. The adsorption layer thickness and the viscosity influence significantly the lubrication characteristics of the contact conjunction. The differences in pressure distribution and film shape between surface forces model and classical EHL model were obvious, especially in the Hertzian contact area. The solvation force has the greatest influence on pressure distribution.
Experimental Study on Direct Displacement-Based Seismic Design of RC Columns
Authors: Lin Y.-Y. , Chang K.-C. , Wang Y.-L. 
Published: May 2011

AbstractFor performance-based seismic engineering of buildings, the direct displacement-based seismic design method is different from the coefficient method used in FEMA-273 and the capacity spectrum method adopted in ATC-40. The method not only is a linear static procedure but also is applied to the design of new constructions. This paper concerns with experimental studies on the accuracy of the direct displacement-based design procedure. Experimental results of three reinforced concrete (RC) columns designed by the displacement procedure are presented and discussed through pseudo-dynamic tests and cyclic loading tests. From the tests, it is shown that the stiffness degrading factor of RC columns plays a key role. The direct displacement-based seismic design method can reliably capture the maximum displacement demand of the test RC columns if the stiffness degrading factor adopted in the displacement design method for RC material is adequate.
Increase in Alphaproteobacteria in association with a polychaete, Capitella sp. I, in the organically enriched sediment
Authors: Kunihiro Tadao , Takasu Hiroyuki , Miyazaki Tomoaki , Uramoto Yuuta , Kinoshita Kyoko , Yodnarasri Supaporn , Hama Daigo , Wada Minoru , Kogure Kazuhiro , Ohwada Kouichi , Tsutsumi Hiroaki 
Published: May 2011

Abstract
We conducted bioremediation experiments on the organically enriched sediment on the sea floor just below a fish farm, introducing artificially mass-cultured colonies of deposit-feeding polychaete, Capitella sp. I. To clarify the association between the Capitella and bacteria on the efficient decomposition of the organic matter in the sediment in the experiments, we tried to identify the bacteria that increased in the microbial community in the sediment with dense patches of the Capitella. The relationship between TOC and quinone content of the sediment as an indicator of the bacterial abundance was not clear, while a significant positive correlation was found between Capitella biomass and quinone content of the sediment. In particular, ubiquinone-10, which is present in members of the class Alphaproteobacteria, increased in the sediment with dense patches of the Capitella. We performed denaturing gradient gel electrophoresis (DGGE) analyses to identify the alphaproteobacterial species in the sediment with dense patches of the worm, using two DGGE fragments obtained from the sediment samples and one fragment from the worm body. The sequences of these DGGE fragments were closely related to the specific members of the Roseobacter clade. In the associated system with the Capitella and the bacteria in the organically enriched sediment, the decomposition of the organic matter may proceed rapidly. It is very likely that the Capitella works as a promoter of bacteria in the organically enriched sediment, and feeds the increased bacteria as one of the main foods, while the bacteria decompose the organic matter in the sediment with the assistance of the Capitella.
MSTd Neurons Encode Nonlinear Combinations of Retinal and Extra-retinal Signals
Authors: Brostek Lukas 
Published: May 2011

AbstractNeuronal activity in the dorsal Medial Superior Temporal area (MSTd) is assumed to depend on both retinal and extra-retinal input. Most of the neurons show activity when presented with a moving large-field visual stimulus. In addition, many MSTd neurons are activated during smooth pursuit eye movements even in the absence of retinal input. However, the interaction between the retinal and extra-retinal input is not yet fully understood.Here we present novel insights regarding the tuning of MSTd neurons for combinations of different input variables using an information-theoretic approach. Neuronal tuning functions can be expressed by the conditional probability of observing a spike given any combination of input variables. However, accurately determining such probabilistic tuning functions from experimental data poses several challenges such as determining the neuronal latencies and finding the combination of input variables which is most related to neuronal activity. Our approach solves these issues by maximizing the mutual information between the probability distributions of spike occurrence and input variables.We analyzed the dependence of MSTd neuronal activity in monkeys on various retinal and extra-retinal signals during presentation of a large-field visual stimulus moving randomly with quasi equally distributed frequencies (white noise). Across the population, neuronal activity depended on different combinations of retinal and extra-retinal input. The interrelation between the input variables exhibited in many cases strong non-linear characteristics. These findings support the hypothesis that MSTd uses a basis function representation for encoding various retinal and extra-retinal signals.
On the quantization of zero-weight super dynamical 𝑟-matrices
Authors: Karaali Gizem 
Published: May 2011

Solutions of the classical dynamical Yang-Baxter equation on a Lie superalgebra are called super dynamical

r
r

-matrices. A super dynamical

r
r

-matrix

r
r

satisfies the zero weight condition if

[
h
⊗
1
+
1
⊗
h
,
r
(
λ
)
]
=
0
for all
h
∈

h

,
λ
∈

h

∗

.

\begin{equation*} [h\otimes 1 + 1 \otimes h, r(\lambda )] = 0 \text { for all } h \in \mathfrak {h}, \lambda \in \mathfrak {h}^*. \end{equation*}

In this paper we explicitly quantize zero-weight super dynamical

r
r

-matrices with zero coupling constant for the Lie superalgebra

g
l

(
m
,
n
)

\mathfrak {gl}(m,n)

. We also answer some questions about super dynamical

R
R

-matrices. In particular, we prove a classification theorem and offer some support for one particular interpretation of the super Hecke condition.