bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non‐classical interface problems for piecewise homogeneous anisotropic elastic bodies
Authors: Jentsch Lothar , Natroshvili David 
Published: October 2005

AbstractTwo non‐classical model interface problems for piecewise homogeneous anisotropic bodies are studied. In both problems on the contact surface jumps of the normal components of displacement and stress vectors are given. In addition, in the first problem (Problem H) the tangent components of the displacement vectors are given from both sides of the contact surface, while in the second one (Problem G) the tangent components of the stress vectors are prescribed on the same surface. The existence and uniqueness theorems are proved by means of the boundary integral equation method, and representations of solutions by single layer potentials are established. In the investigation the general approach of regularization of the first kind of integral equations is worked out for the case of two‐dimensional closed smooth manifolds. An equivalent global regularizer operator is constructed explicitly in the form of a singular integro‐differential operator.
Physical model, theoretical aspects and applications of the flight of a ball in the atmosphere. Part III: Theory in the case of vertical angular frequency and in the general spin‐case
Authors: Fuchs P. M. 
Published: October 2005

AbstractIf a ball is viewed as a rigid body, its flight in the atmosphere can be described by six ordinary differential equations, which has been derived in the first part of this paper.In this following third part, some further theoretical aspects in the case of vertical angular frequency will be pointed out using an unknown transformation of the original independent variable, i.e. the time, as indicated in Part II.Last, but not least, the general case of angular frequency is to be treated. A rough qualitative discussion of the solutions is given as well as—if the equations are viewed as a three‐dimensional dynamical system—the unique stable equilibrium, which depends on the spin. This equilibrium turns out to be globally attractive, which can be proved by the construction of a suitable Ljapunov function. Then, the ball flight system can be transformed into a fourth‐order scalar differential equation.
Global existence and blow‐up for a system of heat equations with non‐linear boundary conditions
Authors: Deng Keng 
Published: October 2005

AbstractIn this paper, we consider non‐negative solutions of magnified imageWe prove that if pq ⩽ 1 every solution remains bounded, while all solutions blow up in a finite time if pq > 1. We also show that if p,q > 1, then blow‐up can only occur on the boundary.
The free boundary problem of a semiconductor in thermal equilibrium
Authors: Jüngel Ansgar 
Published: October 2005

AbstractThe quasi‐hydrodynamic model for semiconductor devices in thermal equilibrium admits in general solutions for which the electron or hole density vanish. These sets are called vacuum sets. In this paper estimates on the vacuum sets and a first step in the regularity of the free boundary of these sets are presented. Numerical examples, including error estimates for linear finite elements, for the devices diode, bipolar transistor and thyristor indicate that the free boundary is more regular than theoretically predicted.
Integral equations for the diffraction problems in the wedge
Authors: Podipenko Ju. K. 
Published: October 2005

AbstractIn the present paper we investigated the boundary value problems appearing in the study of diffraction of acoustical or electromagnetic waves on arbitrary bounded body contained within the wedge. The potential theory has been developed making it possible to reduce the boundary value problems to Fredholm integral equations on the body's boundary. We prove existence and uniqueness of solutions for these integral equations and the boundary value problems.For some other types of domains with infinite boundaries similar problems have been studied in [4, 6–8, 12–14, 19, 20, 22, 23, 25–28].
Stability of semilinear ill‐posed problems with a prescribed energy bound
Authors: Lyashenko A. A. 
Published: October 2005

AbstractIn the present paper we discuss the stability of semilinear problems of the form Aαu + Gα(u) = ƒ under assumption of an a priori bound for an energy functional Eα(u) ⩽ E, where α is a parameter in a metric space M. Following [11] the problem Aαu + Gα(u) = ƒ, Eα(u) ⩽ E is called stable in a Hilbert space H at a point α ϵ M if for any ƒϵH, E, ϵ > 0 there exists δ > 0 such that for any functions uα1, uα2 satisfying Aαjuαj + Gαj(uαj) = ƒαj, Eαj(uαj) ⩽ E, j = 1,2 we have ‖uα1 − uα2H ⩽ ϵ provided ρM(αj, α) ⩽ δ, ‖ƒαj − ƒ‖H ⩽ δ, j = 1,2. In the present paper we obtain stability conditions for the problem Aαu + Gα(u) = ƒ, Eα(u) ⩽ E.
Hyperbolicity of the hydrodynamic model of plasmas under the quasi‐neutrality hypothesis
Authors: Cordier Stéphane 
Published: October 2005

AbstractCollisionless and quasi‐neutral hydrodynamic model of plasmas consisting of electrons and several species of ions are investigated. When two species of ions are considered, the hyperbolicity of the system of transport equations obtained in the quasi‐neutrality limit leads to a restriction on the magnitude of the admissible relative velocities.
Global wellposedness for quasi‐linear symmetric hyperbolic systems with regularized coefficients
Authors: Ascoli Davide 
Published: October 2005

AbstractFollowing the abstract setting of [8] and using the global results of [2], global wellposedness and regularity results are proved for the solutions of quasi‐linear symmetric hyperbolic systems with bounded coefficients which are regularized by a convolution in the space variables with a regularizing function. In the case of unbounded regularized coefficients, local existence of classical solutions is proved, as well as uniqueness and regularity of (not necessarily existing) global weak solutions with initial value in a Sobolev space. As the regularizing function tends to Dirac's δ, local‐in‐time convergence to the classical solution of the non‐regularized problem is proved.
On the stationary quasi‐Newtonian flow obeying a power‐law
Authors: Blavier Eric , Mikelić Andro 
Published: October 2005

AbstractWe investigate in this paper existence of a weak solution for a stationary incompressible Navier‐Stokes system with non‐linear viscosity and with non‐homogeneous boundary conditions for velocity on the boundary. Our concern is with the viscosity obeying the power‐law dependence ν(ξ) = ∣Tr(ξξ*)∣r/2−1, r < 2, on shear stress ξ. It is corresponding to most quasi‐Newtonian flows with injection on the boundary. Since for r ⩽ 2 the inertial term precludes any a priori estimate in general, we suppose the Reynolds number is not too large. Using the specific algebraic structure of the Navier‐Stokes system we prove existence of at least one approximate solution. The constructed approximate solution turns out to be uniformly bounded in W1,r (Omega;)n and using monotonicity and compactness we successfully pass to the limit for r ≥ 3n/(n + 2). For 3n/(n + 2) > r > 2n/(n + 2) our construction gives existence of at least one very weak solution. Furthermore, for r ≥ 3n/(n + 2) we prove that all weak solutions lying in the ball in W of radius smaller than critical are equal. Finally, we obtain an existence result for the flow through a thin slab.
Periodic solutions for differential equations of order three, with application to heat‐flux induced convection
Authors: Néel M. C. , Lyubimov D. 
Published: October 2005

AbstractIn this paper we show the existence of periodic solutions for a class of non‐linear regular vector fields of ℝ3 admitting the trivial solution and depending on a real parameter μ. Two main assumptions lead to this conclusion: first, the right hand‐side of each vector field anticommutes with a reflection. Then, its linear part admits the eigenvalue zero for all variations of μ, and takes the form of a three‐dimensional Jordan block at μ = 0. This result allows the description of the bidimensional stationary patterns induced by a uniform heat‐flux imposed on the boundaries of an infinite porous layer, saturated by a fluid. Indeed, when the filtration Rayleigh number comes close to its critical value, the field of seepage velocity and the field of temperature can be related to a partial differential equation, which admits a three‐dimensional centre manifold. The existence of convective patterns follows. Their length depends on the filtration Rayleigh number, and tends towards infinity when this parameter comes close to its critical value (from above).
On Sommerfeld's half‐plane problem for the equations of linear thermoelasticity
Authors: Erbe Claudia 
Published: October 2005

AbstractThe Sommerfeld screen problem—well known by many publications studying the several mathematical and physical aspects—is generalized to the linear thermoelastic equations. We derive representation formulas of the solution from the data in the whole plane containing the screen. The corresponding boundary integral equations of Wiener‐Hopf type are presented and we obtain important information concerning the factorization of the Wiener‐Hopf operators.
Molecular architecture of the neuromuscular junction
Authors: Hughes Benjamin W. , Kusner Linda L. , Kaminski Henry J. 
Published: October 2005

AbstractThe neuromuscular junction (NMJ) is a complex structure that serves to efficiently communicate the electrical impulse from the motor neuron to the skeletal muscle to signal contraction. Over the last 200 years, technological advances in microscopy allowed visualization of the existence of a gap between the motor neuron and skeletal muscle that necessitated the existence of a messenger, which proved to be acetylcholine. Ultrastructural analysis identified vesicles in the presynaptic nerve terminal, which provided a beautiful structural correlate for the quantal nature of neuromuscular transmission, and the imaging of synaptic folds on the muscle surface demonstrated that specializations of the underlying protein scaffold were required. Molecular analysis in the last 20 years has confirmed the preferential expression of synaptic proteins, which is guided by a precise developmental program and maintained by signals from nerve. Although often overlooked, the Schwann cell that caps the NMJ and the basal lamina is proving to be critical in maintenance of the junction. Genetic and autoimmune disorders are known that compromise neuromuscular transmission and provide further insights into the complexities of NMJ function as well as the subtle differences that exist among NMJ that may underlie the differential susceptibility of muscle groups to neuromuscular transmission diseases. In this review we summarize the synaptic physiology, architecture, and variations in synaptic structure among muscle types. The important roles of specific signaling pathways involved in NMJ development and acetylcholine receptor (AChR) clustering are reviewed. Finally, genetic and autoimmune disorders and their effects on NMJ architecture and neuromuscular transmission are examined. Muscle Nerve, 2005
The role of neurotrophins in muscle under physiological and pathological conditions
Authors: Chevrel Guillaume , Hohlfeld Reinhard , Sendtner Michael 
Published: October 2005

AbstractThis review summarizes the various effects of neurotrophins in skeletal muscle and how these proteins act as potential regulators of development, maintenance, function, and regeneration of skeletal muscle fibers. Increasing evidence suggests that this family of neurotrophic factors not only modulates survival and function of innervating motoneurons and proprioceptive neurons but also development and differentiation of myoblasts and muscle fibers. Neurotrophins and neurotrophin receptors play a role in the coordination of muscle innervation and functional differentiation of neuromuscular junctions. However, neurotrophin receptors are also expressed in differentiating muscle cells, in particular at early developmental stages in myoblasts before they fuse. In adults with pathological conditions such as human degenerative and inflammatory muscle disorders, variations of neurotrophin expression are found, but the role of neurotrophins under such conditions is still not clear. The goal of this review is to provide a basis for a better understanding and future studies on the role of these factors under such pathological conditions and for treatment of human muscle diseases. Muscle Nerve, 2005
Bladder dysfunction in patients with cauda equina lesions
Authors: Podnar Simon , Tršinar Bojan , Vodušek David B. 
Published: October 2005

AbstractAimsData on lower urinary tract (LUT) function obtained in larger, systematically studied populations of patients with cauda equina lesions are limited. We report urinary function in 65 patients with chronic lesions.MethodsA urinary function questionnaire was used, and neurological examination, quantitative electromyography (EMG) of the external anal sphincter (EAS) muscles, EMG assessment of the sacral reflex, and conventional urodynamic measurements were performed.ResultsSevere LUT dysfunction was found in 14%/15%, moderate in 27%/46%, and mild in 46%/39% men/women. Urinary symptoms interfered with daily life in 88%/92% and sexual life in 72%/67% of sexually active men/women. Symptoms of disturbed bladder emptying were the most common (95%/92% men/women), followed by urinary incontinence (56%/71%) and symptoms of overactive bladder (40%/56%). Perianal sensation was abnormal in 96%, EMG of the EAS muscle in 88%, and sacral reflex in 84% of patients. In 40%/17% men/women, a postvoid residual ( >100 ml) was found. On filling cystometry overactive bladder was found in 21%/0%, reduced detrusor capacity in 9%/15%, and during voiding phase an acontractile detrusor or detrusor underactivity were found in 59%/85% men/women. Using multiple linear regression analysis, perianal sensory loss (P = 0.0001) and female gender (P < 0.02) had a significant positive effect on urinary incontinence score.ConclusionsOur study demonstrated significant LUT dysfunction, which disturbed the life of the majority of patients with chronic lesions of the cauda equina. Due to poor correlation between patients' symptoms and urodynamic findings cystometric surveillance is proposed in all patients with significant cauda equina lesions. Neurourol. Urodynam. © 2005 Wiley‐Liss, Inc.
Urinary incontinence and voiding dysfunction after radical retropubic prostatectomy (prospective urodynamic study)
Authors: Majoros Attila , Bach Dietmar , Keszthelyi Attila , Hamvas Antal , Romics Imre 
Published: October 2005

AbstractAimsDuring this prospective study we analyzed the effects of radical retropubic prostatectomy (RRP) on bladder and sphincter function by comparing preoperative and postoperative urodynamic data. The aim of the study was to determine the reason for urinary incontinence after RRP and explain why one group of patients will be immediately continent after catheter removal, while others need some time to reach complete continence.MethodsUrodynamic examination was performed in 63 patients 3–7 days before and 2 months after surgery.ResultsForty‐three (68.2%) and 53 (84.1%) patients regained continence at 2 and 9 months following RRP, respectively. Ten patients (15.9%) were immediately continent after catheter removal. Urodynamic stress incontinence was detected in 18 (28.6%), and detrusor overactivity incontinence in 2 (3.2%) patients 2 months after surgery. The amplitude of preoperative maximal voluntary sphincteric contractions was significantly higher in the postoperative continent group (125 vs. 96.5 cmH2O, P < 0.0001). The patients who were immediately continent following catheter removal had no lower urinary tract symptoms (LUTS) and urodynamic abnormality preoperatively, and they had significantly higher preoperative and postoperative maximum urethral closure pressure (at rest and during voluntary sphincter contraction) than those who became continent later on.ConclusionsThese data suggest that the main cause of incontinence after RRP is sphincteric weakness. In the continent group, those who became immediately continent had significantly higher maximum urethral closure pressure values at rest and at voluntary sphincteric contraction even before the surgery. Neurourol. Urodynam. © 2005 Wiley‐Liss, Inc.
Detection of neurogenic detrusor contractions from the activity of the external anal sphincter in cat and human
Authors: Wenzel Brian J. , Boggs Joseph W. , Gustafson Kenneth J. , Creasey Graham H. , Grill Warren M. 
Published: October 2005

AbstractAimsIndividuals with spinal cord injury or neurological disorders may develop bladder contractions at low volumes (neurogenic detrusor overactivity), which can lead to significant health problems. Present devices can inhibit unwanted contractions through continuous electrical stimulation of sensory nerves, but do not enable conditional stimulation only at the onset of bladder contractions. The objectives of this study were to determine the relationship between the electrical activity of external anal sphincter (EAS) and bladder pressure during neurogenic detrusor contractions and to determine whether EAS activity could be used to detect the onset of bladder contractions.MethodsBladder pressure and EAS electromyogram (EMG) were recorded in nine adult male cats. Retrospective clinical data consisting of bladder pressure and EAS EMG from 41 spinal cord injured individuals with neurogenic detrusor overactivity were analyzed. A CUSUM algorithm was used to detect the onset of bladder contractions from the EAS EMG.ResultsEAS EMG activity increased at the onset of bladder contractions in six cats (dyssynergic) and decreased (synergic) in three cats. The onset of bladder contractions was detected within 3 sec of the start of the contraction for both the synergic and dyssynergic data sets. The onset of bladder contractions was detected within 1 sec of the start of the bladder contraction for both synergic and dyssynergic human subjects.ConclusionsRecordings of the EAS EMG can be used to detect robustly the onset of neurogenic detrusor contractions. The EAS EMG is a suitable signal to control closed‐loop inhibitory electrical stimulation to maintain urinary continence. Neurourol. Urdynam. © 2005 Wiley‐Liss, Inc.
A class of difference ABS‐type algorithms for a nonlinear system of equations
Authors: Spedicato E. , Chen Z. , Deng N. 
Published: October 2005

AbstractIn this paper we give a class of algorithms for solving nonlinear algebraic equations using difference approximations of derivatives. The class is a modification of the original ABS class with the advantage of requiring less function evaluations. Special cases include the methods of Brown and Brent and the discretized Newton method, which is formulated in a way requiring fewer function evaluations per iteration.
A simpler GMRES
Authors: Walker Homer F. , Zhou Lu 
Published: October 2005

AbstractThe generalized minimal residual (GMRES) method is widely used for solving very large, nonsymmetric linear systems, particularly those that arise through discretization of continuous mathematical models in science and engineering. By shifting the Arnoldi process to begin with Ar0 instead of r0, we obtain simpler Gram–Schmidt and Householder implementations of the GMRES method that do not require upper Hessenberg factorization. The Gram–Schmidt implementation also maintains the residual vector at each iteration, which allows cheaper restarts of GMRES(m) and may otherwise be useful.
On a generalized conjugate gradient orthogonal residual method
Authors: Axelsson Owe , Makarov M. 
Published: October 2005

AbstractTo solve a linear system of equations with a generally nonsymmetric matrix, a generalized conjugate gradientorthogonal residual method is presented. The method uses all previous search directions (or a truncated set of them) at each step but, contrary to standard implementations of similar methods, it requires storage of only one set with a linearly growing number of vectors (or the number in the truncated set). Furthermore, there is only one vector (the residual), which must be updated using all the vectors in this set, at each step. In this respect it is similar to the popular GMRES method but it has the additional advantage that it can stop at any stage when the norm of the residual is sufficiently small and no extra computation is needed to compute this norm. Furthermore, the new method can be truncated.The rate of convergence of the method is also discussed.
Stability and convergence of streamline curvature flow analysis procedures
Authors: Bindon Jeffery P. 
Published: October 2005

AbstractA convergence technique for use with the streamline curvature method of cascade and channel flow is presented which produces stable and rapid convergence for subsonic, transonic and supersonic flow and also in the downstream region where the Kutta–Joukowski condition is applied to a cascade flow. The convergence method is fully two‐dimensional in nature, the iterative changes being determined via a model which takes into account the actual streamwise error distribution and the real normal changes in the grid.
Normal gradient boundary condition in finite difference calculations
Authors: Parker R. , Ma C. Y. 
Published: October 2005

AbstractAn outline is given of a method for dealing with curved boundaries in finite difference calculations (relaxation or other similar techniques) where the gradient normal to the boundary is specified. Fluid flow calculations using the velocity potential are typical of such problems and the flow round a circular cylinder is computed as an example. The method makes no approximation which is not made in the usual finite difference techniques, therefore accuracy at the boundary is as good as in the remainder of the field.
Acoustic vibration of a liquid filled distorted circular cylindrical shell
Authors: Firth D. 
Published: October 2005

AbstractA theory is developed whereby acoustic and structural modes are coupled by means of geometrical distortions in a circular cylindrical shell filled with liqued.The prediction is that a circularly symmetric discrete frequency acoustic wave in the liquid will excite in the shell not only a circular symmetric ‘breathing mode’ (which would be the only one present in an undistorted shell) but also short wavelength flexural waves at the excitation frequency. It is possible, even for quite small distortions, for the displacement amplitude of some of these flexural waves to exceed that of the ‘breathing mode’.The results of calculations for a particular shell are shown to be consistent with experimental results.
Seismic response analysis of offshore pipelines in contact with the sea‐bed
Authors: Nath B. , Soh C. H. 
Published: October 2005

AbstractThe seismic behaviour of an offshore pipeline, which may be totally or partially in contact with the sea‐bed, is characterized by the confluence of structural dynamics, hydrodynamics and soil mechanics and also the possible dynamic interactions between these aspects. This paper contains a study dealing with the seismic response analysis of such a pipeline including pressure drag effects. A numerical analysis basesd on the assumption that the pipe behaves linearly elastically and that pipe deffection is elastoplastically related, without loss, to sea‐bed resistance shows that pipe response in significantly attenuated by contact, as aspected, the amount of attenuation depending upon contact length and the parameters defining idealized sea‐bed behaviour.