bluuebunny/crossref_metadata_2025 huggingface dataset:
Translocations t(X;14)(q28;q11) and t(Y;14)(q12;q11) in T‐cell prolymphocytic leukemia
Authors: De OLIVEIRA F. M. , TONE L. G. , SIMÕES B. P. , REGO E. M. , MARINATO A. F. , JÁCOMO R. H. , FALCÃO R. P.
Published: February 2008

We report a case of T‐cell prolymphocytic leukemia (T‐PLL) in a 41‐year‐old male. Classical cytogenetic, spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) studies of a blood sample obtained at diagnosis revealed the co‐existence of t(X;14)(q28;q11), t(Y;14)(q12;q11) and a ring chromosome derivated from i(8)(q10). Immunophenotypic studies revealed involvement of T‐cell lineage, with proliferation of CD4− CD8+. The co‐existence of two translocations involving both sex chromosomes in a case of T‐PLL is rare. Chromosomal instability associated with the disease progression may have allowed the emergence of cell clones with translocations involving the sex chromosomes and the ring chromosome observed.
Haemoglobin A2′ and its significance in β thalassaemia diagnosis
Authors: ABDEL‐GADIR D. , PHELAN L. , BAIN B. J.
Published: February 2008

We have studied, haemoglobin A2′ (A2 prime), a δ chain variant haemoglobin occurring in a small percentage of individuals of African ancestry. In heterozygotes, the percentage of haemoglobin A2′ was found to be slightly lower then the percentage of haemoglobin A2, suggesting that the variant δ chain is synthesized at a reduced rate. When quantifying haemoglobin A2 for the diagnosis of β thalassaemia heterozygosity, it is essential to add together the A2 and A2′ to give ‘total haemoglobin A2’. However, it not necessary to use a different reference range for total haemoglobin A2 in A2′ heterozygotes. When using microcolumn chromatography, A2′ was found to be measured with A2. On the high‐performance liquid chromatography instrument studied, haemoglobin A2′ fell in the haemoglobin S window but its retention time differed from that of haemoglobin S.
An Interactionist Perspective on Genetic and Environmental Contributions to Personality
Authors: South Susan C. , Krueger Robert F.
Published: February 2008

It is now well established that nature and nurture are both important contributors to variation in human personality. As a result, the field of personality behavior genetics is moving beyond simply estimating the magnitude of genetic and environmental influences on various personality constructs. Recent methodological advances provide for the study of how these different sources of influence interact in the development of personality. Specifically, newer biometrical moderation models allow for group‐specific estimates of heritability and environmental influences on personality (a form of gene–environment interaction). In the current paper, we review selected recent research using these models. Furthermore, we explore how moderation might also be important in understanding links between specific genes and personality. Accounting for the contingencies between genes and environment will be an important catalyst for the molecular genetic study of personality, as unmoderated ‘main effect’ types of gene → personality associations have been elusive.
The Psychology of Tailoring‐Ingredients in Computer‐Tailored Persuasion
Authors: Dijkstra Arie
Published: February 2008

Persuasive information can be tailored to individual characteristics using computer technology. Computer technology offers three ways to persuade people: adaptation, personalization, and feedback. Adaptation refers to the match between the type or the formulation of the persuasive arguments or recommendations and an individual's psychological state. Personalization refers to the incorporation of one or more recognizable individual characteristics (e.g., one's first name) in a persuasive text. Feedback refers to providing the individual with information about him or her that relates to important individual goals. These visible elements in a persuasive message are the tailoring‐ingredients of computer‐tailored persuasion. The present article focuses on explaining how these tailoring‐ingredients influence persuasion, using existing social psychological insights in human functioning and persuasion. The persuasive effects of the tailoring‐ingredients can be explained partly by different psychological processes.
Social Categorization and the Perception of Groups and Group Differences
Authors: Krueger Joachim I. , DiDonato Theresa E.
Published: February 2008

The classification of human beings into distinct groups is a fundamental feature of social perception. Problematic phenomena, such as prejudice, discrimination, and intergroup conflict, are commonly traced back to categorization. We explore the minimal conditions under which categorization occurs and the basic mechanisms by which it affects cognition and behavior. We show that comparisons between groups are not necessary for categorization, reveal the conditions under which people overestimate or underestimate differences between groups, and sketch a model showing how social categorization gives rise to differences in the evaluation of ingroups and outgroups and to differences in the accuracy of judgments of ingroups and outgroups. We conclude with reflections on intergroup conflict and the role of moral judgment in such conflicts.
Personality in Non‐human Animals
Authors: Gosling Samuel D.
Published: February 2008

Over the past decade, research on animal personality has flourished in numerous disciplines ranging from Behavioral Ecology and Developmental Psychobiology to Genetics and Comparative Psychology. The broad appeal of animal studies is that, in comparison with human studies, they afford greater experimental control, more options for measuring physiological and genetic parameters, greater opportunities for naturalistic observation, and an accelerated life course. Past research has established that personality (a) exists and can be measured in animals; (b) can be identified in a broad array of species, ranging from squid, crickets, and lizards, to trout, geese, and orangutans; and (c) shows considerable cross‐species generality for some dimensions. The wave of new studies is shedding fresh light on traditional issues in personality research (How do early experiences affect adult personality?), raising novel questions (What are the evolutionary origins of personality traits?) and addressing practical problems (Which dogs are best suited to detecting explosives?).
A video‐simulation study of the management of asthma exacerbations by physicians in India
Authors: Van Sickle David , Singh Raj B.
Published: February 2008

Introduction:  Despite efforts to improve the management of asthma worldwide, few options exist for evaluating the specific needs or the success of these activities in a manner free from bias.

Objectives:  To examine the management of asthma exacerbations by physicians using standardized audiovisual presentations of asthma.

Methods:  Practitioners (n = 70) in Chennai, India were shown the International Study of Asthma and Allergies in Childhood video questionnaire and asked to describe the clinical investigations, emergency treatments and prescription therapy they would recommend for each of the five scenes.

Results:  Practitioners varied significantly in their investigation and treatment of the exacerbations. Those who identified asthma as a possible cause of the scenes were more likely to recommend investigations and treatment congruent with international guidelines, as were those with additional postgraduate training and with specialty training in respiratory disease. Approaches differed significantly for scenes depicting wheeze compared with those depicting cough.

Conclusion:  The management of asthma exacerbations varies significantly depending on whether practitioners identify asthma as a possible cause of the presentation. Standardized audiovisual depictions of asthma offer a useful tool to assess patterns of clinical practice, and to design and evaluate activities to raise the quality of care for asthma.

Please cite this paper as: Van Sickle D and Singh RB. A video‐simulation study of the management of asthma exacerbations by physicians in India. The Clinical Respiratory Journal 2008; 2: 98–105.
Asthma and health‐related quality of life – effect of adjusting for potential confounders
Authors: Voll‐Aanerud Marianne , Eagan Tomas M. L. , Wentzel‐Larsen Tore , Gulsvik Amund , Bakke Per S.
Published: February 2008

Background:  Health‐related quality of life (HRQoL) is an increasingly important outcome measure in medical research. We wanted to evaluate how adjustment for potential confounders affected the relationship between HRQoL and asthma. Furthermore, we wanted to evaluate the relationship of environmental tobacco smoke (ETS) with HRQoL.

Methods:  We carried out a cross‐sectional Norwegian community study in 1996/1997 including 2306 randomly selected subjects aged 26 years–81 years. Data on HRQoL were measured by SF‐12. The data were analyzed by robust linear regression analyses with the physical component score (PCS) and the mental component score (MCS) as dependent variables. The effect of adjusting for the potential confounders was analyzed by bootstrap confidence intervals for differences between the adjusted and unadjusted models.

Results:  The difference in the asthma coefficients between the unadjusted and adjusted models for both PCS and MCS varied from 0.1 to 1.1. The confidence intervals for these differences for PCS were (−0.3, 1.6) and (0.4, 1.8), using the definition ‘asthma last 12 months’ and ‘physician's diagnosis of asthma’, respectively. The confidence intervals for the corresponding differences for MCS were (−0.01, 1.3) and (−0.6, 0.4), respectively. Univariately, PCS was lower among subjects reporting ETS at home compared to people not reporting ETS at home, but this difference did not persist in the multivariate analyses. ETS at home was associated with slightly improved MCS.

Conclusion:  Adjusting for potential confounders does not change the relationship between asthma and HRQoL overtly.

Please cite this paper as: Voll‐Aanerud M, Eagan TML, Wentzel‐Larsen T, Gulsvik A and Bakke PS. Asthma and health‐related quality of life – effect of adjusting for potential confounders. The Clinical Respiratory Journal 2008; 2: 106–115.
Integral stable manifolds in Banach spaces
Authors: Barreira L. , Silva C. , Valls C.
Published: February 2008

We establish the existence of smooth integral stable manifolds for sufficiently small perturbations of nonuniform exponential dichotomies in Banach spaces. We also consider the case of a nonautonomous dynamics given by a sequence of C1 maps. The optimal smoothness of the manifolds is obtained at the same time as their existence, using a convenient lemma of Henry. Furthermore, we obtain not only the exponential decay of the dynamics along the stable manifolds, but also of its derivative. In addition, we give a characterization of the stable manifolds in terms of the maximal exponential growth rate that is allowed, we discuss how the manifolds vary with the perturbations, and we discuss their equivariance with respect to a sequence of linear operators.
VIV of a Composite Riser at Moderate Reynolds Number Using CFD
Authors: Rakshit T. , Atluri S. , Dalton C.
Published: February 2008

The vibratory response of a long slender riser, made of composite materials and subject to an ocean current, is examined for a range of conditions. A major focus of this study is the performance of composite materials when used for risers. The influence of the number of modes of vibration is studied, as is the influence of the mass ratio and the value of the damping coefficient. The flow past the riser is represented by a shear flow, ranging from Re=8000 at the lower end of the riser to Re=10,000 at the upper end of the riser. The riser vibration is treated as a coupled fluid-flow/vibration problem. The fluid-flow equations are represented by a large eddy simulation model for the wake turbulence present in the flow. Strip theory is used to represent different forcing locations along the length of the riser. Since the composite riser has a material damping that is frequency dependent (it decreases with increasing frequency), its response is different from, say, a steel riser with a constant material damping. The composite riser, with variable damping, has a larger rms displacement than a riser with constant damping, primarily because of the smaller mass ratio. The vibration amplitude is found to increase with an increase in the number of modes.
The Hydrodynamic Stability of Pendent Drop Under a Liquid Column
Authors: Lin S. P. , Zhou Z. W.
Published: February 2008

The hydrodynamic stability of a liquid column resting on a gas in a vertical tube with its upper end closed is analyzed. The maximum height above which the interface is unstable is given as a function of the Bond number and the density ratio. The instability is shown to be monotonic, i.e., nonoscillatory.
Hydroelastic Vibration of Rectangular Plates
Authors: Kwak Moon K.
Published: February 2008

This paper is concerned with the virtual mass effect on the natural frequencies and mode shapes of rectangular plates due to the presence of the water on one side of the plate. The approximate formula, which mainly depends on the so-called nondimensionalized added virtual mass incremental factor, can be used to estimate natural frequencies in water from natural frequencies in vacuo. However, the approximate formula is valid only when the wet mode shapes are almost the same as the one in vacuo. Moreover, the nondimensionalized added virtual mass incremental factor is in general a function of geometry, material properties of the plate and mostly boundary conditions of the plate and water domain. In this paper, the added virtual mass incremental factors for rectangular plates are obtained using the Rayleigh-Ritz method combined with the Green function method. Two cases of interfacing boundary conditions, which are free-surface and rigid-wall conditions, and two cases of plate boundary conditions, simply supported and clamped cases, are considered in this paper. It is found that the theoretical results match the experimental results. To investigate the validity of the approximate formula, the exact natural frequencies and mode shapes in water are calculated by means of the virtual added mass matrix. It is found that the approximate formula predicts lower natural frequencies in water with a very good accuracy.
Exact Boundary Condition Perturbation Solutions in Eigenvalue Problems
Authors: Parker R. G. , Mote C. D.
Published: February 2008

A perturbation method is developed for linear, self-adjoint eigenvalue problems with perturbation operators confined to the boundary conditions. Results are derived through third order perturbation for distinct eigensolutions of the unperturbed problem and through second order perturbation for degenerate eigensolutions, where splitting of the degenerate eigensolutions from asymmetry is identified. A key feature, demonstrated for the plate vibration and Helmholtz equation problems on annular domains, is that the solutions of the perturbation problems are determined exactly in closed-form expressions. The approximation in the eigensolutions of the original problem results only from truncation of the asymptotic perturbation series; no approximation is made in the calculation of the eigensolution perturbations. Confinement of the perturbation terms to the boundary conditions ensures that the exact solutions can be calculated for any combination of unperturbed and perturbed boundary conditions that render the problem self-adjoint. The exact solution avoids the common expansion of the solution to the perturbation problems in infinite series of the unperturbed eigenfunctions. The compactness of solution in this formulation is convenient for modal analysis, system identification, design, and control applications. Examples of boundary asymmetries where the method applies include stiffness nonuniformities and geometric deviations from idealized boundary shapes such as annuli and rectangles.
Analytic Solution of Euler’s Equations of Motion for an Asymmetric Rigid Body
Authors: Tsiotras P. , Longuski J. M.
Published: February 2008

The problem of the time evolution of the angular velocity of a spinning rigid body, subject to torques about three axes, is considered. An analytic solution is derived that remains valid when no symmetry assumption can be made. The solution is expressed as a first-order correction to a previous solution, which required a symmetry or near-symmetry assumption. Another advantage of the new solution (over the former) is that it remains valid for large initial conditions of the transverse angular velocities.
Frictional Contact Between the Surface Wave and a Rigid Strip
Authors: Zharii O. Y.
Published: February 2008

A problem of frictional contact between a running surface wave and a motionless rigid strip is considered. The corresponding mixed boundary value problem of elastodynamics is reduced to a singular integral equation for the normal stress distribution and a closed-form solution of it has been found. Boundaries of the contact zone are determined from a system of transcendental equations involving trigonometric functions. Also, simple formulae obtained for kinematic characteristics of solution (tangential velocity inside the contact area, velocity and slope of the free surface outside it). The problem considered represents a limiting case of operating ultrasonic motor when it is completely braked by an external tangential load force.
A Comparison Between the Tiersten Model and O(H) Boundary Conditions for Elastic Surface Waves Guided by Thin Layers
Authors: Bo¨vik P.
Published: February 2008

In this paper we make a comparison between the boundary conditions (BCs) derived by Tiersten and the so-called O(h) BCs for elastic surface waves guided by thin films. By a thin layer we here mean a layer for which the thickness is much smaller than the wavelengths involved. The advantage of the O(h) model is that it starts with the general three-dimensional equation of motion and derives the boundary conditions in a rational manner keeping all terms linear in the layer thickness. The Tiersten model is obtained from the approximate equations for low frequency and flexure of thin plates by neglecting the flexural stiffness. We consider straight-crested surface waves under plane-strain conditions, so-called Rayleigh-type waves (P-SV), and Love waves (SH). It is shown that for the Rayleigh type waves the O(h) BCs gives a much better approximation of the exact case than the Tiersten BCs. Even for the Tiersten model including flexural stiffness, the O(h) BCs yields more accurate results. Concerning Love waves both the Tiersten model and O(h) model reduces to the same dispersion relation which quite well approximates the exact solution.
Effective Thermoelastic Moduli of a Unidirectional Fiber Composite Containing Interfacial Arc Microcracks
Authors: Tandon G. P. , Pagano N. J.
Published: February 2008

In this work, we have employed a variational model to examine the effect of fiber-matrix debonding on the thermoelastic response of a unidirectional composite. The model is designed to represent the concentric cylinder model of a composite representative volume element and it contains the capability to enhance the accuracy of a given numerical solution. The effect of the extent of debonding as well as fiber volume fraction on all the effective moduli of the unidirectional composite has been examined. Numerical results reported in the literature are compared with the results of the model developed in the present study to examine the quality of the model.
Nonlinear Thermo-Viscoelastic Analysis of Interlaminar Stresses in Laminated Composites
Authors: Yi Sung , Hilton H. H. , Ahmad M. F.
Published: February 2008

A finite element formulation for analyzing interlaminar stress fields in nonlinear anisotropic viscoelastic laminated composites is presented including a hygrothermal formulation. Schapery’s single integral formulation is extended to account for viscoelastic anisotropy and multiaxial stress states. Numerical results obtained from the present formulation are compared against experimental data and excellent agreement is obtained between these results. As illustrative examples, inplane and interlaminar stresses for (45/-45)s T300/5208 laminate are also presented.
Viscoplastic Analysis of Adhesive Joints
Authors: Hu G. K. , Schmit F. , Baptiste D. , Franc¸ois D.
Published: February 2008

The uniaxial constitutive law for an adhesive is studied by constant strain rate tensile, creep and relaxation tests. The S-D effect of the adhesive is taken into account by using the Raghava yielding criterion in a three dimensional constitutive formulation. The obtained constitutive law is then used to analyze a single lap joint and a butt joint by a finite element method. Constant cross head speed tensile and creep loading cases are examined. For a butt joint, the results show that the viscous effect and the influence of the hydrostatic stress must be taken into account due to the variation of the hydrostatic stress and of the loading rate in the adhesive layer as function of its thickness. A comparison with experimental results is also given. A good agreement between viscoplastic calculations and experimental results is obtained for single-lap joints. A reasonable result is obtained for butt joints and the discrepancy is attributed to interfacial debonding.
A Fractal Model for the Rigid-Perfectly Plastic Contact of Rough Surfaces
Authors: Warren T. L. , Majumdar A. , Krajcinovic D.
Published: February 2008

In this study a continuous asymptotic model is developed to describe the rigid-perfectly plastic deformation of a single rough surface in contact with an ideally smooth and rigid counter-surface. The geometry of the rough surface is assumed to be fractal, and is modeled by an effective fractal surface compressed into the ideally smooth and rigid counter-surface. The rough self-affine fractal structure of the effective surface is approximated using a deterministic Cantor set representation. The proposed model admits an analytic solution incorporating volume conservation. Presented results illustrate the effects of volume conservation and initial surface roughness on the rigid-perfectly plastic deformation that occurs during contact processes. The results from this model are compared with existing experimental load displacement results for the deformation of a ground steel surface.
Integral Equations for a Three-Dimensional Crack in an Infinite, Fluid-Filled, Poroelastic Solid With Zero Permeability in One Direction
Authors: Kurashige Michio , Clifton R. J.
Published: February 2008

Fundamental solutions for an instantaneous point force and an instantaneous fluid point source are derived for an infinite, fluid-saturated, poroelastic solid with zero permeability in one direction. Applying these solutions and Cleary’s reciprocal theorem to the three-dimensional problem of a pressurized plane crack yields two integral equations, which relate normal tractions and fluid pressure on the crack faces to crack opening and fluid injection rate per unit fracture area. An important application of these equations is the prediction of hydraulic fractures induced during water-flooding of reservoirs to enhance gas and oil recovery. Zero permeability in one direction may be a good approximation for the case in which the reservoir is sandwiched between two impermeable rock layers.
Stress Concentration Factors at an Elliptical Hole on the Interface Between Bonded Dissimilar Half-Planes Under Bending Moment
Authors: Salama Mohamed , Hasebe Norio
Published: February 2008

The problem of thin plate bending of two bonded half-planes with an elliptical hole on the interface and interface cracks on its both sides is presented. A uniformly distributed bending moment applied at the remote ends of the interface is considered. The complex stress functions approach together with the rational mapping function technique are used in the analysis. The solution is obtained in closed form. Distributions of bending and torsional moments, the stress concentration factor as well as the stress intensity factor, are given for all possible dimensions of the elliptical hole, various material constants, and rigidity ratios.
Dynamic Effects of Centrifugal Forces on Turbulence
Authors: Yao L. S. , Moulic S. Ghosh
Published: February 2008

The dynamic effect of suddenly applied centrifugal forces on homogeneous and isotropic turbulence in the entrance region of a curved pipe is analyzed by a perturbation method. The model is for small-scale turbulence and is valid away from the pipe wall; hence is not restricted to a particular cross-sectional shape and can be applied even to external flows if the mean velocity profile is almost uniform, as in the region outside the turbulent boundary layer on a curved surface. The analysis indicates that the major effect of centrifugal forces is to generate pure turbulent shear and this effect is cumulative. Thus, an initially isotropic turbulence become anisotropic due to linear effects. This result is in contrast with the effect of solid-body rotation on isotropic turbulence, where rotation acts on an initially isotropic turbulence only through nonlinear interactions, and pure linear effects influence the double correlations only if the turbulence is initially anisotropic.
Closed-Form Transient Response of Distributed Damped Systems, Part II: Energy Formulation for Constrained and Combined Systems
Authors: Yang Bingen
Published: February 2008

The transient response analysis presented in Part I is generalized for distributed damped systems which are viscoelastically constrained or combined with lumped parameter systems. An energy formulation is introduced to regain symmetry for the spatial differential operators, which is destroyed in the original equations of motion by the constraints, and the coupling of distributed and lumped elements. As a result, closed-form solution is systematically obtained in eigenfunction series.
Thermomechanical Equations Governing a Material With Prescribed Temperature-Dependent Density With Application to Nonisothermal Plane Poiseuille Flow
Authors: Cao D. , Bechtel S. E. , Forest M. G.
Published: February 2008

The standard practice in the literature for modeling materials processing in which changes in temperature induce significant volume changes is based on the a posteriori substitution of a temperature-dependent expression for density into the governing equations for an incompressible material. In this paper we show this ad hoc approach misses important terms in the equations, and by example show the ad hoc equations fail to capture important physical effects. First we derive the three-dimensional equations which govern the deformation and heat transfer of materials with prescribed temperature-dependent density. Specification of density as a function of temperature translates to a thermomechanical constraint, in contrast to the purely mechanical incompressibility constraint, so that the constraint response function (“pressure”) enters into the energy equation as well as the momentum equation. Then we demonstrate the effect of the correct constraint response by comparing solutions of our thermomechanical theory with solutions of the ad hoc theory in plane Poiseuille flow. The differences are significant, both quantitatively and qualitatively. In particular, the observed phenomenon of expansion cooling is captured by the thermomechanically constrained theory, but not by the ad hoc theory.
Non-Newtonian Creep Into a Two-Dimensional Cavity of Near-Rectangular Shape
Authors: Bogobowicz A.
Published: February 2008

The plane-strain formulation for the steady-state closure of a near-rectangular, single isolated opening in an indefinite viscoelastic medium is presented. A power creep law describes the creep behavior of the viscous medium. Because of the highly nonlinear nature of the creep, an analytic solution is not possible for the proposed opening geometry, hence an approximation method based upon the minimum principle for velocities is used. The analytic function is used to describe the shape of opening (circular, elliptical, and rectangular with rounded corners).
Effect of the Interphase Zone on the Bulk Modulus of a Particulate Composite
Authors: Lutz M. P. , Zimmerman R. W.
Published: February 2008

An exact solution is found for the problem of hydrostatic compression of an infinite body containing a spherical inclusion, with the elastic moduli varying with radius outside of the inclusion. This may represent an interphase zone in a composite, or the transition zone around an aggregate particle in concrete, for example. Both the shear and the bulk moduli are assumed to be equal to a constant term plus a power-law term that decays away from the inclusion. The method of Frobenius series is used to generate an exact solution for the displacements and stresses. The solution is then used to estimate the effective bulk modulus of a material containing a random dispersion of these inclusions. The results demonstrate the manner in which a localized interphase zone around an inclusion may markedly affect both the stress concentrations at the interface, and the overall bulk modulus of the material.
A Pressure Projection Method for Nearly Incompressible Rubber Hyperelasticity, Part I: Theory
Authors: Chen Jiun-Shyan , Pan Chunhui
Published: February 2008

A least-squares-based pressure projection method is proposed for the nonlinear analysis of nearly incompressible hyperelastic materials. The strain energy density function is separated into distortional and dilatational parts by the use of Penn’s invariants such that the hydrostatic pressure is solely determined from the dilatational strain energy density. The hydrostatic pressure and hydrostatic pressure increment calculated from displacements are projected onto appropriate pressure fields through the least-squares method. The method is applicable to lower and higher order elements and the projection procedures can be implemented into the displacement based nonlinear finite element program. By the use of certain pressure interpolation functions and reduced integration rules in the pressure projection equations, this method can be degenerated to a nonlinear version of the selective reduced integration method.
On the Eigenstrain Problem of a Spherical Inclusion With an Imperfectly Bonded Interface
Authors: Zhong Z. , Meguid S. A.
Published: February 2008

This article provides a comprehensive theoretical treatment of the eigenstrain problem of a spherical inclusion with an imperfectly bonded interface. Both tangential and normal discontinuities at the interface are considered and a linear interfacial condition, which assumes that the tangential and the normal displacement jumps are proportional to the associated tractions, is adopted. The solution to the corresponding eigenstrain problem is obtained by combining Eshelby’s solution for a perfectly bonded inclusion with Volterra’s solution for an equivalent Somigliana dislocation field which models the interfacial sliding and normal separation. For isotropic materials, the Burger’s vector of the equivalent Somigliana dislocation is exactly determined; the solution is explicitly presented and its uniqueness demonstrated. It is found that the stresses inside the inclusion are not uniform, except for some special cases.
Exact Solutions for Laminated Piezoelectric Plates in Cylindrical Bending
Authors: Heyliger P. , Brooks S.
Published: February 2008

Exact solutions are presented for the problem of piezoelectric laminates in cylindrical bending under an applied surface traction or potential. An arbitrary number of elastic or piezoelectric layers can be considered in this analysis. Example problems are considered for several representative cases, with resulting displacement, potential, stress, and electric displacement distributions shown to demonstrate the effects of the electroelastic coupling.
Random Field Representation and Synthesis Using Wavelet Bases
Authors: Zeldin B. A. , Spanos P. D.
Published: February 2008

The paper addresses the representation and simulation of random fields using wavelet bases. The probabilistic description of the wavelet coefficients involved in the representation of the random field is discussed. It is shown that a broad class of random fields is amenable to a simplified representation. Further, it is shown that a judicious use of the local and multiscale structure of Daubechies wavelets leads to an efficient simulation algorithm. The synthesis of random field samples is based on a wavelet reconstruction algorithm which can be associated with a dynamic system in the scale domain. Implementation aspects are considered and simulation errors are estimated. Examples of simulating random fields encountered in engineering applications are discussed.
Exact Time-Dependent Plane Stress Solutions for Elastic Beams: A Novel Approach
Authors: Ladeve`ze P. , Simmonds J. G.
Published: February 2008

We consider an elastically isotropic beam of narrow rectangular cross section governed by the dynamic equations of linearized plane stress theory and subject to typical boundary and initial conditions associated with flexure. We use one of the three stress-displacement relations to express the axial stress σx in terms of the axial displacement U and the normal stress σ. Assuming this latter stress and the shear stress τ to be given functions of position (x, z) and time t, we write the remaining two stress-displacement equations as a nonhomogeneous hyperbolic system for U and the normal displacement W. This system has a simple, explicit solution in terms of σ, τ, and V, the value of W on the centerline of the beam. Introducing certain body forces fx and fz, we obtain explicit formulas for σ, τ, U, and W valid in the interior of the beam and satisfying any imposed tractions on the faces of the beam. We satisfy initial conditions by adding certain explicitly computable increments to the initial displacements and velocities. Satisfaction of end conditions of displacement or traction yields a certain consistency condition along the centerline in edge zones (“boundary layers”) of width vH, where v is Poisson’s ratio and 2H is the depth of the beam. In particular, if V is taken as a solution of the equations of elementary beam theory, then outside these end zones the body forces fx and fz and the incremental initial conditions are “small.” If V within the edge zones is also identified with the solution of elementary beam theory, then a certain increment of the order of the dominant longitudinal stress σx must be added within the edge zones to the prescribed value of T on the face of the beam. (This is consistent with the neglect of two-dimensional end effects in elementary beam theory.) These results should be of use as analytical benchmarks for checking numerical codes.
Closed-Form Transient Response of Distributed Damped Systems, Part I: Modal Analysis and Green’s Function Formula
Authors: Yang Bingen
Published: February 2008

An analytical method is developed for closed-form estimation of the transient response of complex distributed parameter systems that are nonproportionally damped, and subject to arbitrary external, initial, and boundary excitations. A new modal analysis leads to the Green’s function formula for the distributed system and an eigenfunction expansion of the system Green’s function. The legitimacy of the modal expansion is also shown.
Investigation of a New Formulation of the Lagrange Method for Constrained Dynamic Systems
Authors: Rosen A. , Edelstein E.
Published: February 2008

Lagrange multipliers are often used in order to model constrained dynamic systems. This method results in problems of constraints violations and therefore various methods of constraints stabilization have been presented in the past. The purpose of the present paper is to present a new formulation of the method that stabilizes the constraints, but unlike other stabilization methods it is also consistent within the framework of variational methods. The new formulation can be applied to holonomic or nonholonomic constraints. After the presentation of the new formulation, its application to constrained rigid rod systems is presented. The results of the new method are compared with other stabilization techniques.
A Variable Sensitivity Displacement Interferometer With Application to Wave Propagation Experiments
Authors: Espinosa H. D. , Mello M. , Xu Y.
Published: February 2008

The present paper introduces a variable sensitivity displacement interferometer (VSDI) used to monitor both normal and in-plane particle displacements in wave propagation experiments. The general system consists of two interferometers working in tandem. Normally reflected light is interfered with each of two symmetrically diffracted light beams generated by the specimen rear surface. In cases where the surface motion simultaneously exhibits both in-plane and normal displacements, the fringes represent a linear combination of the longitudinal and transverse components of motion. Decoupling of the normal and in-plane displacement histories may be achieved through a linear combination of the two VSDI records. Alternatively, it is always possible to decouple the components of motion by combining a VSDI record with an independent measurement of either component. Moreover, it is shown that in the case of pure normal motion, the VSDI system functions as a desensitized normal displacement interferometer (DNDI). Similarly, in situations involving purely in-plane motion, the VSDI is shown to function as a desensitized transverse displacement interferometer (DTDI). The DNDI and DTDI fringe sensitivities are in general shown to depend on the angle θ or equivalently, the frequency σ of a grating manufactured at the observation point and the order n of the diffracted beams. The variable sensitivity feature of the VSDI greatly desensitizes normal displacement measurements and is particularly well suited for wave propagation studies in which normal particle velocities in excess of 100 m/s are generated. Experimental results are presented which demonstrate the application of this technique to monitoring particle motion histories in plate impact recovery experiments.
Contact Between Elastic Bodies With an Elliptic Contact Interface in Torsion
Authors: Cuttino J. F. , Dow T. A.
Published: February 2008

When two elastic three-dimensional bodies of specified radii come into contact, Hertzian forces at the interface result in the formation of an elliptical contact area. The rotation of one body relative to the other about an axis normal to the contact induces a nonlinear torque due to the progression of sliding in the contact interface. Using finite element analysis, a relationship describing torsional compliance with slip is presented for two elastic bodies with an elliptic contact interface under pure twist. The effect of changing material and geometric parameters is studied, and the relationships between torque generation and angle are defined with respect to these nondimensionalized parameters.
Predicted Thermal Mismatch Stresses in a Cylindrical Bi-material Assembly Adhesively Bonded at Its Ends
Authors: Suhir E.
Published: February 2008

A simple analytical stress model, based on the strength-of-materials approach, is developed for the evaluation of thermally induced shearing stresses in a long cylindrical bi-material assembly adhesively bonded at its ends and subjected to the change in temperature. The emphasis is on the interaction of the “global” thermal mismatch stresses, counted with respect to the mid cross section of the assembly as a whole, and the “local” stresses, counted with respect to the mid cross sections of the bonded regions. The effect of the coefficient of thermal expansion of the adhesive material itself is also considered. We show also how to evaluate the fundamental frequency of vibrations of the inner cylinder with consideration of the thermally induced tension, if any.
Poroelastic Solution for an Inclined Borehole
Authors: Cui L. , Cheng A. H-D. , Abousleiman Y.
Published: February 2008

The analytical solution for an infinitely long borehole in an isotropic, poroelastic medium, inclined to the far-field principal stresses, is presented. The solution utilizes a loading decomposition scheme which leads to three fundamental problems: a poroelastic plane-strain, an elastic uni-axial, and an elastic antiplane shear problem.
Nonlinear Elasticity of Granular Media
Authors: Norris A. N. , Johnson D. L.
Published: February 2008

The finite and incremental elasticity of a random packing of identical spheres is derived using energy methods. We consider different models for the contact forces between spheres, all of which are based upon or related to the fundamental Hertz theory; we consider only the special cases of perfect friction (no tangential slip) or no tangential friction. The existence of a strain energy function for the medium depends critically upon the type of contact. If the tangential contact stiffness is independent of the normal force, then the energy is well defined for all values of the macroscopic strain. Otherwise, the strain energy of the system is path dependent, in general. However, the concept of a quadratic strain energy function is always well defined for incremental motion superimposed on large confining stress and strain. For all models considered, we derive the changes in wave speeds due to incremental strains. For the models based upon an energy function we derive expressions for the third-order elastic constants as a function of confining pressure.
Seismic Waves in a Laterally Inhomogeneous Layered Medium, Part I: Theory
Authors: Zhang Ruichong , Zhang Liyang , Shinozuka Masanobu
Published: February 2008

Seismic waves in a layered half-space with lateral inhomogeneities, generated by a buried seismic dislocation source, are investigated in these two consecutive papers. In the first paper, the problem is formulated and a corresponding approach to solve the problem is provided. Specifically, the elastic parameters in the laterally inhomogeneous layer, such as P and S wave speeds and density, are separated by the mean and the deviation parts. The mean part is constant while the deviation part, which is much smaller compared to the mean part, is a function of lateral coordinates. Using the first-order perturbation approach, it is shown that the total wave field may be obtained as a superposition of the mean wave field and the scattered wave field. The mean wave field is obtainable as a response solution for a perfectly layered half-space (without lateral inhomogeneities) subjected to a buried seismic dislocation source. The scattered wave field is obtained as a response solution for the same layered half-space as used in the mean wave field, but is subjected to the equivalent fictitious distributed body forces that mathematically replace the lateral inhomogeneities. These fictitious body forces have the same effects as the existence of lateral inhomogeneities and can be evaluated as a function of the inhomogeneity parameters and the mean wave fleld. The explicit expressions for the responses in both the mean and the scattered wave fields are derived with the aid of the integral transform approach and wave propagation analysis.
Differential Equations Governing the Geometry of a Diamond Mesh Cod-end of a Trawl Net
Authors: O’Neill F. G.
Published: February 2008

A new surface, made up of an infinite number of infinitesimal meshes, is defined to approximate the cod-end. The force balance on a mesh element of this surface is considered in the limit as the mesh size tends to zero and the differential equations governing the geometry of a diamond meshed cod-end of circular cross section are derived in cartesian coordinates. The parametric form of the equations in terms of a, the distance along the cod-end profile, is then deduced and some special cases examined. In particular the case of a partially filled cod-end hanging under gravity is investigated and experimental measurements are compared with numerically obtained theoretical predictions. The numerical results are shown to provide a good description of the cod-end geometry except where the cod-end diameter is at its narrowest where there is a systematic departure of the predicted values from those measured. It is demonstrated that a probable explanation of this discrepancy is the assumption that the knots are simple points of intersection rather than finite well-defined structures.
Linear Complementary Formulations Involving Frictional Contact for Elasto-Plastic Deformable Bodies
Authors: Li Maocheng , Sha Desong , Tamma K. K.
Published: February 2008

In the present study, an incremental variational inequality is described for frictional contact problems with material non linear behavior assumed to be elasto-plastic for the contacting bodies. On the contacting boundaries, the constraint conditions include noninterpenetration along the normal direction of the contact boundary and Coulomb friction law in the sliding direction. After numerical discretization using the finite element method, an effective linear complementary formulation is then established with two unknown variables and two complementary variables for each contact nodal pair. The proposed developments permit a reduced number of unknown variables which are chosen as the gap function for the normal direction and the norm of the incremental sliding displacements for the tangential direction; and the complementary variables are taken as the normal contact forces and slack variables in the tangential directions. The resulting linear complementary equations are then solved employing an explicit Conjugate Gradient Based Projection (CGBP) method in conjunction with a generalized Newton-Raphson iteration procedure to account for the material nonlinear behavior. The methodology is valid for three-dimensional frictional contact representations; however, for purposes of illustration of the proposed approaches, attention is confined to applications involving two-dimensional static elasto-plastic problems under small deformation. Numerical examples are presented which clearly show that the developments satisfy the problem physics and contact conditions with features to include high accuracy and reduced computational costs.
Inverse Finite Element Characterization of Nonlinear Hyperelastic Membranes
Authors: Kyriacou S. K. , Shah A. D. , Humphrey J. D.
Published: February 2008

It is advantageous in mechanics to identify experiments that correspond to tractable boundary value problems—this facilitates data reduction and interpretation. Increasingly more situations are arising, however, wherein experimentalists cannot dictate the geometry or applied loads during testing. Inverse finite element methods are, therefore, becoming essential tools for calculating material parameters. In this paper, we present numerical and experimental results that show that one such inverse finite element method is very useful in characterizing the mechanical behavior of neo-Hookean (rubber) membranes subjected to axisymmetric and nonaxisymmetric finite inflations.