bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the effect of the wall roughness and free stream turbulence on the boundary layer development
Authors: Jonáš P. , Mazur O. , Uruba V. 
Published: February 2009

AbstractDevelopment of a flat plate boundary layer (grad P = 0) was investigated in the closed type wind tunnel (0.5 × 0.9 × 2.7 m3). The plate was either aerodynamically smooth or covered with a thin plate (10 mm thick) with the surface made from the sand paper (grits 80). FST is generated by square mesh plane grids/screens set across the flow as to produce homogeneous, close to isotropy turbulence with various scales of velocity and length. The surface roughness was of transient type. The comparison is made of the effect of various grouping of the wall roughness and FST on the boundary layer development. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Modified Statistical Interparticle Collision Model For Colliding Particle Clouds
Authors: Kloss C. , Pirker S. 
Published: February 2009

AbstractIn this paper, a modified stochastical interparticle collision model is discussed and valdiated. A channel flow with a constriction serves as a test case. The simulation of the thereby colliding particle strands clearly shows that without the collision sub–model, the simulation with the standard Lagrangian model yields unreasonable results. After adding the stochastical collision sub–model, the Lagrangian model is able to describe the flow situation if the mass load is not too high. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The relationship between the vortical structure and the wall shear stress in a blind trough cavity subject to a jet impingement
Authors: Knob M. , Uruba V. 
Published: February 2009

AbstractIn a blind trough cavity subject to a jet– impingement, the jet switching phenomenon has been known for decades. The large vortices, formed by the Kelvin– Helmholtz instability play a crucial role in this phenomenon– they are the main cause of the fluid entrainment phenomenon, which consequently evoke the Coanda effect and finally results in the jet switch. As the jet swings, the vortical structure inside the cavity changes together with the impinigement point. The aim of this article is to describe the relationship between the wall shear stress, i.e. the motion of the impingement point, and the vortical structure.The analysed data were obtained using the TR PIV system, the caity aspect ratios 16:24 and 18:24, jet hydraulic diameter based Reynolds numbers 3000, 11200 and 19600, and the impingement angles 0°, 5°, 10° and 15°. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of heat transfer and fluid flow in laser welding
Authors: Kotalík Pavel , Boeck Thomas 
Published: February 2009

AbstractAxisymmetric 2D heat transfer including solid–liquid phase transitions coupled with surface tension driven flow of molten metals is studied numerically for pulsed laser welding. We show that the pulse modulation in time influences the temperature, melting front and flow velocity which, together with the expected undercooling, may explain the fine–grain structure of the resolidified welds that have better strength and, possibly, no cracks inside. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Solution of Newtonian and Non‐Newtonian Flows in Bypass
Authors: Prokop V. , Kozel K. 
Published: February 2009

AbstractThis paper deals with a numerical solution of laminar incompressible steady flows of Newtonian and non–Newtonian fluids through bypass of a restricted vessel. Blood flow is considered to be Newtonian in the case of vessels of large diameters as aorta. On the other hand, with decreasing diameter of a vessel the non–Newtonian behavior of blood can play a significant role. One could describe these problems using Navier–Stokes equations and continuity equation as a model. In the case of Newtonian fluids one considers constant viscosity compared to non–Newtonian fluids where viscosity varies and can depend on the tensor of deformation. In order to find numerical solution, the system of equations is completed using an artificial compressibility method. The space derivatives are discretised using a cell centered finite volume method and arising system of ordinary differential equations is solved using an explicit multistage Runge–Kutta method with given steady boundary conditions. The steady solution is achieved for time t→∞ and steady boundary conditions. The results can be used in the field of cardiovascular research. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Up‐scaled Dynamical Model of the Human Vocal Folds
Authors: Triep Michael , Klostermann Jens , Schwarze Rüdiger , Brücker Christoph 
Published: February 2009

AbstractFlow and volume flow measurements are carried out through a driven 3:1 up–scaled glottis model. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Propagation of Sound Waves in Partially Saturated Soils
Authors: Albers Bettina 
Published: February 2009

AbstractWe investigate the propagation of sound waves by means of a newly constructed model in a sandstone filled with two immiscible fluids. The speeds and attenuations of the four emerging waves (one transversal, three longitudinal) are illustrated in dependence on frequency and initial saturation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diffraction of water waves by a slotted cylindrical breakwater
Authors: Basmat A. 
Published: February 2009

AbstractPermeable and slotted breakwaters are becoming more popular, in order to reduce the drawback of rigid coastal structures: namely large reflections, forces and overtopping. The linearized theory of water waves is used to examine the diffraction of incident regular waves by a vertically slotted cylindrical breakwater that consists of a number of distinct rigid cylindrical panels. Under the assumption that the wavelength is much greater than the thickness, each segment is replaced by a thin structure and the permeability is modelled by suitable boundary conditions. The first condition is the matching pressure and normal velocity conditions between two internal and external fluid regions and the second condition is zero normal velocity on rigid panels. The mixed boundary–value problem is transformed to dual series relations and the least–square method is applied to get the forces on the structure. The results are presented to illustrate the effects of permeability. Numerical results compare well with McCamy and Fuchs predictions for the limiting case of an impermeable rigid cylinder. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Trapped‐mode and gap‐band effects in elastic waveguides with obstacles
Authors: Glushkova Natalia , Glushkov Evgeny , Golub Mikhail , Boström Anders 
Published: February 2009

AbstractTraveling wave propagation in elastic waveguides with obstacles in the form of cracks, voids, inclusions or surface irregularities is considered. The investigation is focused on the trapped–mode phenomena featured by the time–averaged harmonic wave energy localization near the obstacles in the form of energy vortices. The latter results, in particular, in narrow gap bands in the frequency plots of transmission coefficients. The study is carried out using analytically based computer models relying on wave expressions in terms of path Fourier integrals, Green's matrices for the laminate structures, and asymptotics for body and traveling waves derived from those integrals. The connection between the resonance effects and natural frequencies (spectral points of the related boundary value problems) in the complex frequency plane is analyzed as well. Examples of spectral points touching the real axis in the course of varying crack size are presented. The eigenforms associated with such discrete spectral points lying in a continuous spectrum depict strong wave energy localization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Damage detection in plates by wave propagation analyses
Authors: Meyfarth Daniel , von Ende Sven , Lammering Rolf 
Published: February 2009

AbstractAt locations with defects the propagation of elastic waves in solids is disturbed. This behaviour can be used for the development of new structural health monitoring and quality assurance systems. In the sense of adaptive structure systems actuators of piezo–electric materials [1] are implemented to generate high frequency waves (Lamb waves) in plate like structures, [2]. At flaws, imperfections of the structure and surface defects these waves show reflections, refractions and mode conversions. The observation of the wave propagation and the wave behaviour at possible flaws and surface defects is performed by an optical measurement system. Measurement data of the thin walled metallic plates are compared with numerical and analytical solutions. First results of the detection of the wave propagation in metallic plates are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impedance eduction from energy dissipation measurements with flow
Authors: Richter Christoph , Thiele Frank , Busse Stefan , Heuwinkel Claus , Röhle Ingo , Enghardt Lars , Michel Ulf 
Published: February 2009

Abstract	An optimization method for the calculation of the wall impedance of a perforate from measurements under grazing flow conditions is presented.	It is in particular characterized by the simultaneous eduction of the parameter set defining the impedance as function of frequency,	which allows interpolation and extrapolation.	The Extended Helmholtz Resonator is applied as impedance model and the simultaneous eduction is performed	using a time–domain CAA method.	Furthermore, the method uses processed energy data from experiments to define the objective function.	The results give an insight in the effect of bias flow on the wall impedance under grazing flow conditions.	It proves to be an important acoustic design parameter. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Wave Propagation in Complex Structures with the Spectral Element Method
Authors: Schulte R. T. , Fritzen C.‐P. 
Published: February 2009

AbstractIn nondestructive testing, the use of ultrasonic elastic waves has proven as one of the most successful principles to detect structural damage like cracks, delaminations etc. Especially, Structural Health Monitoring (SHM) is characterized by permanently installed embedded or surface–mounted actuators and sensors (e.g. piezoelectric patches). The capability of most approaches strongly depends on adequate choice of parameters like excitation signals and actuator/sensor positions. For this reason there is a growing interest in efficient and accurate simulation tools to shorten time and cost of the necessary pretests. With respect to high frequency excitation a computationally efficient method is required. This contribution presents the theoretical background of the spectral element method including the electro–mechanical coupling of piezo elements. The spectral element method generates a diagonal mass matrix leading to significant savings of memory and to a crucial reduction of complexity of the time integration algorithm. Both in–plane and out–of–plane waves can be handled. Numerical examples for the propagation of waves in stiffened structures are presented. The effect of improper placement of actuators/sensors is shown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vertical Vibrations of a Vehicle Excited by Real Road Profiles.
Authors: Borowiec Marek , Litak Grzegorz , Hunicz Jacek , Koszałka Grzegorz , Niewczas Andrzej 
Published: February 2009

AbstractWe analyze experimental acceleration data obtained from the delivery car vibration test in working conditions. The vertical components of unsprung and sprung mass accelerations have been analyzed by using the Fourier analysis. In particular we examine the response of the sprung mass on various road excitations and conclude the efficiency of the car suspension. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of flows over inclined wavy bottoms
Authors: Häcker Tobias , Uecker Hannes 
Published: February 2009

AbstractWe study the flow of an incompressible liquid film down a wavy incline. Starting from the Navier–Stokes equations we derive an integral boundary layer equation (IBLe) by applying a Galerkin method with a single test and ansatz function. In comparison with older models this approach has several advantages. First, a linear stability analysis for stationary solutions yields a critical Reynolds number which corresponds in the limit of a flat incline with results directly obtained by the Navier–Stokes equations. Second, the IBLe is consistent with the pertinent Benney equation. Finally, the velocity profile is not assumed to be parabolic, so that also parameter regimes with recirculations can be modelled. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The sensitivity analysis of the drawpiece response on the finite element shape parameter
Authors: Kaldunski Pawel , Kukielka Leon 
Published: February 2009

AbstractOn this paper the numerical analysis of the drawing process is presented. The sensitivity analysis of the drawpiece response on the finite element shape parameter is realized. The sensitivity of stresses field on the edge and the round edge of drawpiece on the change sizes of the finite elements is defined. Precisely proportion between height and length of the finite element is examined. The analysis with the explicit method in the ANSYS LS–Dyna system is passed. The die and the stamp as not deformable bodies are accepted and with the shell finite elements are discretized. The drawpiece with the solid finite elements are discretized. Examples results of computer simulations are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analytical Solution for the Deformation of a Cylinder under Tidal Gravitational Forces
Authors: Scheithauer Silvia , Lämmerzahl Claus 
Published: February 2009

AbstractQuite a few future high precision space missions for testing Special and General Relativity will use optical resonators which are used for laser frequency stabilisation. These devices are used for carrying out tests of the isotropy of light and of the universality of the gravitational redshift. As the resonator frequency not only depends on the speed of light but also on the resonator length, the quality of these measurements is very sensitive to elastic deformations of the optical resonator itself. As a consequence, a detailed knowledge about the deformations of the cavity is necessary.In this note we derive for the first time an analytical solution for the problem of an elastic, isotropic, homogeneous free–flying cylinder in space under the influence of a tidal gravitational force. A detailed derivation can be found in [4]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization for contact problems with friction on rough interface
Authors: Orlik Julia , Nam Alexander 
Published: February 2009

AbstractWe consider a contact problem between a macroscopic solid with a smooth boundary and a technical textile, while the textile has a periodic microscopic structure and microscopically rough surface. Two–scale homogenization approach is applied to the problem. The microscopic solution is approximated in terms of macroscopic solution and some concentration factor, given as a solution of auxiliary boundary value or contact problems of elasticity on the periodicity cell. Local friction condition is represented as a continuous non–linear functional over the stress field. Two–scale convergence is used to prove the convergence of friction functional. The macroscopic initial frictional limit is found. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale analysis and reconstruction of time series of stochastic cascade processes
Authors: Nawroth Andreas , Wächter Matthias , Peinke Joachim 
Published: February 2009

AbstractWe propose a new method to generate synthetical time series of hierarchical stochastic processes. Based on the statistics of n–scale joint PDFs, the stochastic properties of a time series are modeled simultaneously on many scales. The application to a data set of turbulent velocities is demonstrated, showing the ability of the approach to reproduce the correct statistics of the original time series on all considered scales. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of the dynamic blanking process
Authors: Bohdal Lukasz , Kukielka Leon 
Published: February 2009

AbstractIn this paper an optimization of the dynamic blanking process with using E–PLANNER, ANSYS and MATLAB programmes was presented. The main aim of this work was to obtain the high quality of the cut surface in function of: the size of clearance between punch and die, value of fillet radius of the punch edge and the speed of blanking. Numerical analysis were conducted in Ansys LS–Dyna programme, with use of the explicit method and the experiment plan had been done before. Five levels rotary plan, was used. Unknown coefficients in mathematical model in the shape of quadratic equation with interactions were obtained. Obtained regression function was optimized in MATLAB programme, and determined optimal value of the process parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On bounds for ratios of posterior expectations under asymmetric loss functions
Authors: Preda Vasile , Ciumara Roxana 
Published: February 2009

AbstractWe compute the bounds of the Bayesian premium when the prior distribution belongs to the ε‐contaminated class of priors and the loss function is weighted asymmetric Linex, by applying a result of Gomenz–Deniz et al [1]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Genetic Algorithm Optimization of a Six Degree of Freedom Micro Parallel Robot
Authors: Stan S.‐D. , Mătieş V. , Bălan R. 
Published: February 2009

AbstractIn this paper a mono–objective optimum design procedure for a six–degree of freedom parallel micro robot is outlined by using optimality criterion of workspace and numerical aspects. A mono–objective optimization problem is formulated by referring to a basic performance of parallel robots. Additional objective functions can be used to extend the proposed design procedure to more general but specific design problems. A kinematic optimization was performed to maximize the workspace of the mini parallel robot. Optimization was performed using Genetic Algorithms. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solving regularized total least squares problems via a sequence of eigenvalue problems
Authors: Lampe Jörg , Voss Heinrich 
Published: February 2009

AbstractA computational approach for solving regularized total least squares problems via a sequence of eigenvalue problems has recently been introduced by Renaut and Guo. Combining this approach with thick starts using the nonlinear Arnoldi method lead to a very efficient method for large RTLS problems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a matrix associated to a matrix pair
Authors: Virnik Elena 
Published: February 2009

AbstractFor a c–stable matrix pair (E,A), i.e., all finite eigenvalues of (E,A) have negative real part, an associated c–stable matrix is provided. It has all finite eigenvalues of (E,A) as eigenvalues and an additional stable eigenvalue −α, where α may be chosen arbitrarily, which corresponds to the eigenvalue ∞ of (E,A). In the case of positive systems, this associated c–stable matrix is, in addition, shown to be a −M‐matrix. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
How residual bounds for restarted GMRES describe the real behaviour
Authors: Zítko Jan 
Published: February 2009

AbstractGiven a system of linear equations Ax=b with a nonsingular matrix A, new bounds for the norm of the residual vector are presented and shown by example. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies on molten bath and aluminium contamination with ceramic anodes corrosion products
Authors: Rodean Cristian Paul , Rodean Simona 
Published: February 2009

AbstractTwo types of tin oxide ceramic anodes with 3 different bulk densities are prepared and tested in a laboratory aluminium reduction cell. During normal electrolysis, the regular chemical dissolution process of anode material should be controlled by mass–transport and subsequent reduction of the corrosion products into the cathode metal. The content of Sn species from each experimental anode in the electrolyte reaches stable values and does not contribute to the time dependent corrosion. Their concentration in metal becomes linear with time, providing that the concentration in the electrolyte remains constant. The mass transport anode dissolution mechanism is experimentally confirmed and it becomes evident that the dissolution rate is largely dependent by the conditions at the cathode, which has a hundred times lower rate factor. The smallest aluminium contamination (under 0.2 wt %) and corrosion rate (under 1 cm/year) were obtained by testing the tin oxide anode, with Recipe 2 (2) – 96% SnO2+2%Sb2O3+2%CuO by our own sintering procedure and with bulk densities bigger than 6.5 g⋅cm−3 prepared. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the direct numerical methods for systems of integral equations with nonlinear delays
Authors: Tynda Alexander N. 
Published: February 2009

AbstractIn this paper we investigate the possibility of a construction of direct numerical methods for systems of nonlinear Volterra–type integral equations. One of the unknown functions of such systems is in the limit of integration. Two numerical schemes based on the piecewise constant and piecewise linear approximation of the exact solutions are suggested. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal Control of an Axisymmetric Conical Shell with a Unilateral Elastic Foundation and Rigid Supports
Authors: Bock Igor , Lovíšek Ján 
Published: February 2009

AbstractWe study an optimal control problem for an elastic conical shell. The displacement vector u=(u,v) is then a function of one variable s∈(a,b), 0<a<b<∞. Here u is the meridional and v the normal displacement. The shell is assumed to be simply supported. Moreover, we consider several unilateral obstacles and an unilateral elastic foundation of Winkler type i.e. the reaction force is proportional of the positive part of the normal displacement. The state problem is formulated in a form of variational inequality for u. The design parameter e=(t,z,F) includes the variable thickness of the shell, the stiffness characteristics of the foundation and the friction coefficient. The existence of the optimal control will be explained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Active Vibration Damping and Model‐Based Control for an Adaptronic Actuator
Authors: Ast Alexandra , Eberhard Peter 
Published: February 2009

AbstractThe static and dynamic flexibility of a machine tool is often the major limiting factor for the machining quality, especially if high processing speeds as well as high accuracies are desired. Particularly parallel kinematic machines, which have been developed for high processing speeds and accuracy and which often use lightweight structures, can suffer from severe problems with vibrations of system components and the loss of accuracy due to deformations of machine parts. Introducing so–called adaptronic or smart components into the machine tool structure opens up new and interesting possibilities to actively control the deformations and vibrations of flexible machine parts. They allow to specifically target such undesired properties and to significantly reduce or even eliminate their influence on the system performance. Concepts of active vibration damping and model–based control are presented here for such an adaptronic actuator implemented in a machine tool with parallel kinematics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)