bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Shell Theory in Convective Description
Authors: Herold M. , Ulbricht V.
Published: March 2011

Starting from the basic equations of the three‐dimensional continuum a shell theory will be derived, considering geometrically and physically nonlinear effects, transverse shear strains and thickness stretching. Motion is described using a material description with convected coordinates. This means the independent variables are the material coordinates θi of the material points r and the time t. Due to the specifics of this description the shape of the coordinate lines, the base vector system and the metric are dependent on space and time. In this case a rate formulation of the field equations proves to be useful, which leads to a nonlinear initial‐boundary value problem.

The nonlinearity is implied in the initial value problem whereas the boundary value problem is linear in terms of displacement rates.
An improved reduced basis method to solve nonlinear problems
Authors: Imazatene A. , Zahrouni H. , Potier‐Ferry M.
Published: March 2011

Many works have established the efficiency of asymptotic numerical methods (direct computation of series, the use of Padé approximants, or the reduced basis technique) to solve nonlinear problems (see ]1[). It has been written (see ]2[ that the reduced basis technique (Rayleigh‐Ritz method) is the most efficient in term of step lenght. Nevertheless, as long as a cheaper algorithm to compute the coefficients of the reduced problem is not found, the most attractive technique remains the rational fictions. In this work is presented an attempt to reduce this computation time. The method consists an coupling Padé approximants with the reduced basis technique in order to obtain an efficient algorithm.
Numerical Simulation of Mechanical Behaviour of Textile Surfaces
Authors: Janński L. , Ulbricht V.
Published: March 2011

The paper presents a model which can be used for calculations of complex mechanical behaviour of textile surfaces e.g. surfaces obtained from a drapemeter. Fabric is treated an this model as a two‐dimensional continuum. As kinetic and kinematic measures are used these of the Cosserat continuum. Linear elastic, orthotropic constitutive equations which enable independent treatment of the in plane and out of plane deformations, describe material behaviour of the textile structure.
Randintegralgleichungsverfahren zur Berechnung der Fluid‐Struktur Interaktion
Authors: Nolte B.
Published: March 2011

Mit der numerischen Kopplung von Randintegralgleichungen kann man die akustische Fluid‐Struktur‐Interaktion be‐rechnen. Vorteil ist die automatische Erfüllung der Sommerfeldschen Ausstrahlbedingung in den Außenraumgebieten, da die Greenschen funktionen des Vollraumes der zugrundeliegenden partiellen Differentialgleichungen Verwendung finden. Eine klassische Finite‐Element Formulierung führte in diesen Fall zu artifiziellen Rändern mit physikalisch nicht existierenden Eigenlösungen im Außengebiet.
Simple model for the vertical displacements computation of a single cracked cantilever under tension loads
Authors: Skrinar M.
Published: March 2011

The paper considers the approach for computation of transverse displacements for a single cracked cantilever beam under tensile axial force. Transverse displacements obtained with the proposed model by solving a differential equation are comparable to equivalent solutions obtained by implementing huge finite element meshes.
Numerical Efficiency of Different Partitioned Methods for Fluid‐Structure Interaction
Authors: Steindorf J. , Matthies H. G.
Published: March 2011

The numerical simulation of coupled problems is one of the great challenges in scientific computing. In this paper, we consider partitioned methods for unsteady fluid‐structure interaction, where different codes are used for the different physical domains. There are various procedures how to couple the fluid and structure part: the coupling conditions and the moving domain can be treated in a fully explicit or implicit or in a mixed explicit/implicit manner. Depending on the different coupling procedures, the numerical efficiency of the staggered partitioned methods is investigated.
Segmentation of Piezo‐Elements in Structural Vibration Control
Authors: Pietrzakowski M.
Published: March 2011

The paper is aimed at active damping of structural vibrations of a simply supported beam by using multiple piezoelectric patches as collocated sensors and actuators. The control concept is based on the velocity as well as proportional‐velocity feedback. Dynamic responses of the system are obtained by applying the static model of actuatorsubstructure coupling with perfect bonding. For the suppression of the low modes several arrangements of the sensor/actuator pairs are proposed and numerically investigated.
The Stability and Sensitivity Analysis of Structure Supporting Turbo‐generator with Regard to Parametric Effects
Authors: Wójcicki Z. , Grosel J.
Published: March 2011

The paper is continuation of the research presented in GAMM'98. The problem of the influence of an axial vibration (axial dynamic loads) of the columns which are parts of the structure supporting turbo‐generator on the lateral parametric vibration this structure is analysed. The general conclusion is that the axial vibration changes the parametric steady‐state lateral vibration very much and it is inadmissible to neglect its influence. Moreover, the dynamic instability regions can be observed, despite of it that the magnitude of the whole axial force is only about 30% of the Euler's critical value for the column. The dynamic stability and the first order sensitivity analysis in the time domain of the steel, spatial, orthogonal frame supporting small turbo‐generator structure ]1[ shown in Fig. 1 is carried out. One column is extracted from the original structure, Fig. 2. Dimensions, stiffness and mass parameters of the strut are the same as in the structure supporting turbo‐generator. Rotary inertia of mass element at the top of the column and rotary stiffness of spring fixed the column are chosen to fit particular eigenvalue of the original structure, The axial and lateral sinusoidal changing forces, periods of which are commensurable, load this elastic fixed column. The FEM is used to solve the dynamic model. Numerical and analytical calculations are supported by the computer system “Mathematics”, “COSMOS/M” as well as author's software.
Linear‐quadratic optimal control of high index singularly perturbed systems
Authors: Mikhailov S. A. , Müller P. C.
Published: March 2011

We consider singular singularly perturbed problems (SSPP) where the reduced DAE system has index > 1. Using terminology of descriptor systems literature, we will call these systems high index singularly perturbed systems. Tikhonov‐Levinson theory and standard time‐scale modeling do not apply for the SSPP. Therefore the related subjects have to be considered in the course of linear‐quadratic optimal control design. These difficulties can be alleviated by means of decoupling the slow and fast motions in SSPP. We analyse the general structure of optimal hear‐quadratic control design.
Stability of a rotor supported on journal bearings with piezoelectric elements
Authors: Przyblowiczm P.
Published: March 2011

The paper is concerned with stability analysis of a rotor supported on journal bearings with circular piezoelectric bush made of lead zirconate titanate (PZT). It is known that, apart from many other structural parameters, the oil gap in journal bearings constitutes one of the most important factors responsible for stability of such systems. The piezoelectric ring is capable of changing its radial dimension under a voltage applied to it. The voltage signal can be coupled with angular velocity of the rotor that makes the system adaptive to varying operational conditions. It means that increasing angular velocity slightly diminishes the oil gap what protects the rotor from self‐excited vibration that normally occurs at a certain critical rotation speed. The paper is 20 find the answer 20 what extent the method is effective, i.e. to evaluate quantitatively how far it can shift the critical threshold towards higher rotation speeds, enlarging this way the range of stable working of the rotor.
On the effective elasticity tensor of cellular materials obtained by an energetic homogenization procedure
Authors: Hohe J. , Becker W.
Published: March 2011

Aim of the present study is the determination of the effective elastic properties of cellular materials using two‐dimensional cellular structures which are common as core materials for structural sandwich panels as a model material. The cellular microstructure is homogenized by a strain‐energy based RVE‐procedure assuming that strain states, which are equivalent on the macroscopic level, lead to equal strain energy in a representative volume element whether the real microstructure or the quasi‐homogeneous “effective” medium is considered.
Bending of Beams in Superelasticity Domain
Authors: Kosel Franc , Bundara Borut
Published: March 2011

The paper deals with bending of beams made of shape memory material (SMM). The research is focused on the modelling of a bending process in the superelasticity region, which w one of the characteristics of SMM. On the basis of a chosen physical model, a computer program has been set up for numerical modelling of the stress‐strain and displacement state in a beam made of a SMM exhibiting superelasticity, subjected to bending load. The proposed physical model has been verified experimentally using specimens made of Ni‐Ti alloys. The shape‐memory effect is a unique property that some alloys possess according to which, after being deformed at one temperature, they recover their original shape upon being heated to another temperature. The built‐in memory is produced by the martensitic transformation. The effect was first discussed the Russian metallurgist G. Kurdjumov. In 1951, L. C. Chang and T. A. Read reported its occurrence in an Ni‐Ti alloy. However, application of this phenomenon came only after the development of the Ni‐Ti alloy by the Naval Ordnance Laboratory (NITINOL) in 1968. Many technical problems have been successfully solved using some of the features of SMM like one‐way shape memory, pseudoelasticity, two‐or multi‐way shape memory effect. However, designers encounter many problems trying to analytically determine stresses, strains and displacements of structural elements of SMMs. Two separate mechanical effects characterise the response of SMM, these are: strain‐memory effect and superelasticity. Both of these phenomena strongly depend on temperature. In some alloys both of these effects can appear but at a different temperature. In this paper our research is focused on studying the superelastic phenomenon of a SMM. The superelasticity phenomenon can appear in a SMM in the case when two conditions have to be fulfilled as follows: a.) The temperature in the SMM has to be between the finish austenite temperature Af and the pseudoelastic temperature Md; and b.) A value of stress state in the SMM has to be appropriate so that the stress martensite can appear.
The Method of Asymptotic Expansion for Plate Problem in the Linear Theory of Viscoelasticity
Authors: Lotfi A. , Molnárka G.
Published: March 2011

The method of asymptotic expansion originally developed for elasticity problems is generalized to linear stic problems. Three‐dimensional, unsteady problems corresponding to a class of viscoelastic plates are considy employing the Laplace transform, the original problem is converted to an equivalent elastic problem, where mptotic expansion method is used. An application of this method to the Maxwell model is also presented.
Design Sensitivity of the Beam with Periodically Variable Geometry under Harmonic Excitation
Authors: Mazur‐Jniady K. , Sniady P.
Published: March 2011

The paper presents an approach to the problem of testing the sensitivity of a structure to the change of its design parameters on the example of a beam. In the paper the dynamic responce of periodic‐like straight beam with variable cross section is analysed. The approach adapted in the paper is baaed on concepts of the dynamics of periodic‐like structure ]1[. In this way we are able to formulate the averaged equations of structured beams which describe the length‐scale effect.
A study to determine an adequate constitutive equation for the behaviour of beech wood
Authors: Silber G. , Benderoth G.
Published: March 2011

Living organisms are optimized by nature due to minimize the consumption of material and energy for building and maintaining themselves. Therefore all load bearing structures are weight minimized for resisting a particular load. Technical materials are still far away from load/weight relations adchieved by nature ]4[‐ It is worth while to examine these “natural experiments” to use the results for building more efficient structure with regard to materials. As an objekt of investigation wood stems were chosen because the load cases are quite simple (bending by wind forces and compression by the crown and stem 's own weight) and the internal structure of the composite material shows only transversal isotropy.
A Minimum Problem Defining Effective Isotropic Elastic Properties
Authors: Böhlke T. , Bertram A.
Published: March 2011

The paper discusses a special aspect of averages approximating the elastic properties of polycrystalline aggregates with a uniform orientation distribution. It is shown that the well known isotropic estimations by Voigt and Reuss and a recently suggested geometric mean of the local elasticity tensors minimize their distances to the single crystal elasticity tensors as well as to the corresponding volume averages. In this analysis, only the influence of the grain orientation distribution on the macroscopic response is considered.
Can Linear Potential Theory Predict Supersonic Jets?
Authors: Dillmann A.
Published: March 2011

Fifty years ago D.C. Pack presented his analytical series solution for a slightly over‐or underexpanded supersonic jet emerging from a circular nozzle. However, non‐uniform convergence, caused by singularities, makes direct numerical evaluation impossible. Therefore, Pack was unable to verify his solution, and during the following decades there was considerable doubt about its physical relevance. The present paper aims at answering the above question by a direct comparison of experimental Mach‐Zehnder interferograms with corresponding theoretical images computed from Pack's analytical solution.
Optimal path synthesis of the four‐bar mechanism
Authors: Iztok Ciglaric , Krasna Simon , Prebil Ivan
Published: March 2011

Four‐bar mechanisms are widely used in different devices as leading mechanisms that have to provide desired and often complicate motion and sustain substantial forces, accelerations and jerks. As the four‐bar mechanism seems to be a simple device, it is well known that dimensional synthesis is an exacting piece of work. One has to determine the proportions of link lengths needed to accomplish the specified motion and force transformation. Paper discusses optimal synthesis of four‐bar mechanism. The objective of this approach is to determine the optimal values of the mechanism link lenghts, to minimize the difference between the trajectory “T” of the arbitrary point C on the mechanism coupler link and prescribed trajectory “P”, while hinge forces have to remain within the prescribed values.
Optimization of Patch Reinforcements around Circular Holes in Isotropic and Anisotropic Plates
Authors: Engels H. , Becker W.
Published: March 2011

For various technical reasons cutouts like holes in thin‐walled structures are often inevitable. Applied loads lead to an undesired stress concentration and respective strength degradation in the hole vicinity. In order to reattain the requested strength in practice a local hole reinforcement is applied. The techniques of mathematical structural optimization have been applied in order to determine an optimal design for the hole reinforcement.
Erweitertes Optimierungsverfahren für den Spritzgießprozess
Authors: Meckbach S. , Ehrenstein G. W.
Published: March 2011

Zur Prozessoptimierung beim Spritzgießen wird ein Betriebspunkt bestimmt, an dem vorgegebene Eigenschaften der Teile eingehalten werden und der Prozess unempfindlich gegen Störungen ist. Das vorgestellte Optimierungskonzept basiert auf Antwortflächen, welche durch Scattered Data Interpolation Methoden erzeugt werden. Probleme die im Zusammenhang mit der Wahl des geeigneten Interpolationsmodells auftreten werden diskutiert.
RSM Based Design Optimization
Authors: Rijpkema J. J. M. , Schoops A. J. G. , Etman L. F. P.
Published: March 2011

Response Surface Models (RSM) based on data from designed numerical experiments are useful as approximation models in Engineering Optimization. Their construction can be enhanced by the inclusion of design sensitivity data. In this short paper we discuss two strategies to accomplish this. We compare both strategies in a numerical example and draw some general conclusions regarding their practical value.
Distributed Dynamic Process Simulation
Authors: Ehrhardt K. , Borchardt J. , Grund F. , Horn D.
Published: March 2011

In chemical process industry a heterogeneous simulation concept is required which distributes the solution of a dynamic overall model to a computer network such that the submodels of the global process flowsheet can be solved independently of each other on subsequent time intervals. To this end a iteration technique is used which estimates the vector of input variables of the submodels, calculates the corresponding time behaviour of the output variables concurrently, and matches then the profiles of the interconnecting variables of the overall process model iteratively. For the common case that the submodels do not provide input‐output sensitivities a specific Broyden‐type acceleration of this waveform iteration method is considered.
Computing roots of matrix products
Authors: Fassbender H. , Benner P.
Published: March 2011

The problem of computing a kth root of a matrix product W = Πki=1 Ai is considered. The explicit computation of W may produce a highly inaccurate result due to rounding errors, such that the computed root W1/k is far from the actual root W1/k. An algorithm for computing the square root of W is presented which avoids the explicit computation of W by employing the periodic Schur decomposition and therefore yields better accuracy in the computed root W1/2. In principle, the techniques are applicable to k > 2 as well but lead to solving 2 × 2 polynomial matrix equations which are difficult to treat. The case k = 3 is also addressed briefly.
The generation of high quality difference and error formulae of arbitrary order on 3‐D unstructured grids
Authors: Adolph T. , Schónauer W.
Published: March 2011

We generate difference and error formulae of arbitrary consistency order on 3‐D unstructured grids for the finite difference method. Therefore we have to collect grid points so that we can determine the influence polynomials on which the generation of the formulae is based. The problem is to select the appropriate points so that we receive a well‐structured system of equations of the finite difference method and a good error estimate. We present an algorithm for this selection that is controlled by two parameters. The high quality of the formulae is shown by an example.
On the Numerical Solution of the Hyperbolic Evolution Problem on Closed Curve
Authors: Roman Chapko
Published: March 2011

We consider on evolution problem for a hyperbolic equation with the Dirichlet to Neumann operator. For the numerical solution we combine the Laguerre transformation with respect to the time variable and the boundary integral equation method. Then an infinite sequence of the integral equations of the second kind with a logarithmic singularity is obtained. The full discretization is realized by Nyström's method which is based on trigonometric quadrature rules.
Reichweitensteigerung bei Hyperschall‐Notflugbahnen durch Optimalsteuerung des Treibstoff‐Ablaßvorgangs
Authors: Sachs G. , Mayrhofer M.
Published: March 2011

Ein Missions‐Abbruchszenario von zweistufigen Raumtransportsystemen betrifft antriebslose Notflugbahnen der Orbitalstufe nach Trennung von der Trägerstufe. Hierfür wird dargelegt, daß die optimale Steuerung des Treibstoff‐Ablaßvorgangs eine Steigerung der erzielbaren Reichweite ermóglicht.
Rotating polyhedral flames
Authors: Class A. G.
Published: March 2011

By systematically changing the mixture composition of a flame on a Bunsen burner the conical shape of the flame can suddenly be transform into triangular cells forming a polyhedron. Often the polyhedron rotates rapidly about its vertical axis. We present a weakly nonlinear analysis which results in a Kuramoto‐Sivashinsky equation describing cellular flames, which is coupled to a heat equation modeling the temperature of the burner rim. Numerical computations of the coupled set of equations exhibit rapidly rotating polyhedral patterns, which show the typical saw‐toothed shape of the corrugations of the flame. In contrast to earlier considerations of this problem, where the rotation is explained as a result of mode interactions, we find a primary bifurcation to a rotating state, which may explain the high speeds of revolution.
A remark on second order methods in control of fluid flow
Authors: Hinze Michael
Published: March 2011

We present the functional analytic framework for a tracking‐type control problem of the instationary Navier‐Stokes equations. As solution methods for the control problem we comparatively discuss Newton's method as an example of the black box approach, and the SQP‐method as one of the all‐at‐once methods. It is argued that black box approaches in general outperform all‐at‐once methods since the numerical effort necessary to numerically solve linearizations of the instationary Navier‐Stokes equations compares to that of the nonlinear Navier‐Stokes system. We report a numerical comparison which illustrates our argumentation. For both approaches local convergence results are cited.
On the interaction of a 2‐dimensional transonic turbulent boundary layer with a localized 3‐dimensional disturbance
Authors: Kluwick A. , Kronberger R.
Published: March 2011

If a weak normal shock wave impinges on a fully attached transonic turbulent boundary layer, a three layer structure develops. In the outer defect region the solution of the interaction problem may be described as an irrotational perturbation to the oncoming stream. Hence a potential can be introduced, which is governed by a generalized transonic small‐disturbance equation. In the present study it is shown that, for a suitable scaled problem, the interaction of the incoming boundary layer with a small 3‐dimensional obstacle can be described by an equation of similar type. Numerical studies are carried out focusing on the formation of the local supersonic region within the defect region of the boundary layer.
Numerical investigation of the spin‐up of a two‐layer fluid
Authors: Mang J. , Ungarish M. , Schaflinger U.
Published: March 2011

The spin‐up of a two‐layer fluid with a free surface in a cylindrical container rotating about a vertical axis is investigated numerically, using axisymmetric finite differences. As Linden & van Heijst (1984) have shown, the flow inside the viscous boundary layer at the bottom leads to the accumulation of the heavier lower‐layer fluid near the side wall. Thereby, a bare spot in which the light fluid is in direct contact with the bottom is formed around the axis. The present simulation gives new insight into the internal structures and interaction of the two fluids. Preliminary results indicate strong mixing inside the region of heavy fluid.
Universal wall‐boundary conditions for turbulence‐transport models
Authors: Rung T. , Lübcke H. , Thiele F.
Published: March 2011

In the industrial design process of fluids engineering devices, the use of numerical simulation is of ever increasing importance. The predictive quality of such simulations is often governed by the representation of turbulence. Virtually all industrial simulations mimic the influence of turbulence by a closure model based on transport equations for statistical turbulence properties. Besides the derivation of such transport‐equation models, the adequate formulation of wall‐boundary conditions has come into the focus of attention. Conventional boundary conditions rely on the validity of specific flow conditions pertaining to the wall‐shear stress and the resolution properties of the computational grid in the wall‐adjacent region. Since the shear stress is part of the simulation result, this approach—strictly speaking—requires the anticipation of the solution. Moreover, it significantly affects the efficiency and flexibility of the simulation due to the associated mesh constraints. The principal aim of this research is the development of a universal boundary condition. Examples included show encouraging results for attached and separated flows.
Creeping Newtonian Film Flow Down an Inclined Wavy Plane. Part I
Authors: Scholle M. , Wierschem A. , Aksel N.
Published: March 2011

Theoretical investigations are made on the influence of a sinusoidal bottom topography on a gravity driven, Newtonian film flow. Neglecting inertia effects the surface shape is obtained for small amplitudes of the bottom profile using perturbation theory. For thick films and large bottom amplitudes an exact analytical approach is developed.
An eddy viscosity scaled dynamic scale similarity model
Authors: Wagner C.
Published: March 2011

A new subgrid scale model for Large Eddy Simulations (LES) of wall‐bounded turbulent flows, which is based on scale similarity between resolved stresses and subgrid scale stresses, is proposed. Testing this model a posteriori, the fully developed turbulent channel flow was simulated for a low Reynolds number (based on the channel height H and friction velocity uT) of Re = 360. Additionally a coarse direct numerical simulation (DNS) without model and a LES with a dynamic Smagorinsky model were performed. Excellent agreement is obtained applying the new model in comparison with Kim et al.'s ]2[ DNS data base.
Inexact Newton‐Krylov Methods for Nonlinear Forced Heat Convection Problems by BEM
Authors: Hriberšek M.
Published: March 2011

A preconditioned inexact Newton‐Krylov nonlinear iterative method is constructed for computation of nonlinear heat transfer problems by Boundary Element Methods. The performance of the iterative method is tested on conjugate heat transfer problem in a thick wall channel.
Instability of buoyant‐thermocapillary flows in non‐cylindrical liquid bridges
Authors: Nienhüser Ch. , Kuhlmann H. C. , Rath H. J.
Published: March 2011

The flow driven by buoyancy and thermocapillarity in a liquid bridge between coaxial differentially heated disks held by surface tension forces is investigated. We numerically determine the stability of axisymmetric flows by a linear stability analysis. In the present approach, the influence of buoyancy forces on the flow stability is taken into account through static meniscus deformations as well as through internal buoyancy. To elucidate the physical instability mechanisms the energy balance given by Reynolds‐Orr‐like equations is considered term by term.
Plane channel flow with heat transfer: Stability analysis with a commercial CFD‐code
Authors: Severin J. , Beckert K. , Herwig H.
Published: March 2011

Spatial development of small amplitude disturbances in plane Poiseuille flow is investigated numerically using a commercial CFD code (CFX 4.2). Small amplitude Tolmien‐Schlichting waves known from an Orr‐Sommerfeld analysis are superimposed as initial conditions on a fully developed laminar channel flow. The downstream spatial disturbances are calculated on the basis of the full Navier‐Stokes equations (NSE). Results are compared to calculations based on the Orr‐Sommerfeld equations (OSE). In a second step the thermal energy equation is solved in addition to the NSE to investigate temperature effects and especially the development of temperature disturbances.
A multi‐phase soil model including a soil‐foundation interface
Authors: Ehlers W. , Blome P.
Published: March 2011

In the present contribution, the frictional material soil is considered within the well‐founded framework of the Theory of Porous Media ]1–3[. The model represents a multi‐phase medium consisting of a solid skeleton, a pore‐liquid (here water) and a pore‐gas (here air). Concerning the solid skeleton, a general elasto‐plasticity approach including a soil‐foundation interface is presented. In particular, to describe granular soils like sand, a physically non‐linear soil elasticity law ]4[ is taken into consideration. In the plastic domain, use is made of the single‐surface yield function by Ehlers ]2[, which is extended towards isotropic work‐hardening materials.
Direct numerical simulation of three‐dimensional flame instabilities
Authors: Gerlinger W. , Schneider K. , Bockhorn H.
Published: March 2011

The evolution of premixed gas flames near extinction and stability limits is of primary interest for many applications in combustion technology. Under such conditions the flames are very sensitive, and exhibit quasi‐steady state behaviour so that they are well‐suited to determine flammability limits. We show three‐dimensional numerical simulation of the transient behaviour of lean H2‐air flames. The thermo‐diffusive equations are solved by means of a parallelized Fourier‐pseudospectral code. We compute the evolution of freely propagating spherical flames, whereby the influence of the initial flame radius is investigated. The results exhibit different behaviour as found in experimental studies under microgravity conditions, i.e. the splitting due to cellular instabilities, extinction, and stationary flame balls.
3D simulations of turbulent deflagrations using dynamic grid adaptation
Authors: Huld Thomas , Wilkening Heinz
Published: March 2011

We present a CFD code for simulating turbulent deflagrations in gas mixtures for studies of explosion accidents. A dynamic grid adaptation method is used to increase the accuracy of the calculation in regions of interest, such as at flame and shock fronts. The numerical simulations compared with experimental data and is shown to yield strongly improved results at at modest cost in computational time.
Computations of NOx Emissions of Domestic Boilers
Authors: Thévenin D. , Gicquel O. , Darabiha N.
Published: March 2011

Due to severe regulations concerning pollutant emissions, practical devices using combustion to release energy must be designed from the start using accurate, predictive numerical tools. A partially premixed methane/air flame in a two‐dimensional configuration is investigated in this work. This configuration is close to those used in real domestic gas boilers. The flame structure and flow pattern are calculated using complex chemistry and detailed transport models. A post‐processing method is then used to predict NO emission.

Computations are performed for two configurations. The two cases have the same primary and secondary mass flow‐rates and equivalence ratio. The only difference between them is the introduction of an insert inside the primary injector.

Both results have been compared to measurements. Calculations are found to be in good agreement with the flame shapes observed experimentally. The classical burner shows a Bunsen‐type flame while the one with an insert has a totally different shape (butterfly‐type flame). NO emission levels are also well predicted in both configurations. The butterfly flame induces a reduction in NO emission. This reduction seems to be due to the increased mixing between the burnt gases and the secondary air jet, which homogenizes the temperature distribution and reduces the maximum temperature.
On Noncoercive Models in the Theory of Inelastic Deformations with Internal Variables
Authors: Krzysztof Chelmiski
Published: March 2011

In the theory of inelastic deformations with internal variables, H.‐D. Alber has defined an important class of models called models of monotone type. For the subclass containig coercive models, the existence of global in time solutions is known. Unfortunately, in practice the coerciveness condition fails very often. Therefore we consider here noncoercive problems. In this note we study a subclass of models of monotone type for which the so‐called coercive approximation converges to a solution of the original noncoercive problem.
On the Model Chan‐Bodner‐Lindholm in the Theory of Inelastic Deformation
Authors: Piotr Gwiazda
Published: March 2011

We prove global in time existence and uniqueness of large solutions for a problem in the nonlinear theory of inelastic deformations with internal variables for nonhomogeneous boundary conditions. The proof is based on the nonlinear nonautonomous semigroup method.
How to scale reconstruction filters in 2D‐computerized tomography
Authors: Rieder A.
Published: March 2011

The state‐of‐the‐art reconstruction algorithm in 2D tomography is the filtered backprojection algorithm. The quality of the reconstructed density function depends crucially on the proper scaling of the reconstruction filter in relation to the discretization step size. We show how to do it the right way in the parallel scanning geometry.
The Alpha‐1 Association Genetic Counseling Program: An Innovative Approach to Service
Authors: McGee Dawn , Strange Charlie , McClure Rebecca , Schwarz Laura , Erven Marlene
Published: March 2011

In an era of specialty medicine, genetic counselors are becoming increasingly focused in their service provision. The Alpha‐1 Association Genetic Counseling Program, established in September 2007, specializes in confidential toll‐free genetic counseling provided by a certified genetic counselor for Alpha‐1 Antitrypsin deficiency, a co‐dominant condition associated with lung and/or liver disease. The program received more than 600 callers in its first 2 years. Sixty‐seven percent of new callers were family members, carriers, or health professionals. The number of callers increased between the first 2 years, with the greatest increases being family members and health professionals. Testing options and explanation of results encompassed 60% of initial reasons for calls. Seventy‐two percent of referrals came from family and friends, test result letters, and the Alpha‐1 Association. Between year 1 and 2 family member referrals showed the largest increase. This disease‐specific genetic counseling program provides a model that may be useful for other rare disease communities.
Expertise et construction de la valeur artistique (XIVe-XVe siècle)
Authors: Anheim Étienne
Published: March 2011

À partir d’un corpus de contrats de commande toscans des XIVe et XVe siècles, cet article montre qu’avant d’être un sujet de discussion dans les milieux lettrés et humanistes, la peinture est d’abord l’objet de pratiques concrètes d’évaluation au sein du milieu professionnel des peintres. L’étude porte sur l’analyse juridique et économique des clauses d’expertise par lesquelles peintres et commanditaires soumettaient l’oeuvre à d’autres peintres pour garantir la bonne exécution du contrat, constituant ainsi un dispositif d’évaluation essentiel pour l’économie de la peinture.
Un « artiste connaisseur»? L'expertise du restaurateur dans l'institution muséale à la fin du XVIIIe siècle
Authors: Etienne Noémie
Published: March 2011

L’expertise du restaurateur de peintures se définit à Paris à la fin du XVIIIe siècle dans l’institution muséale. D’une part, cet article présente les compétences revendiquées par le praticien pour justifier de son expertise et se créer une identité professionnelle distincte de celles des autres acteurs impliqués. D’autre part, ce texte montre comment cette expertise est construite dans les rapports de travail du commissaire-expert et du restaurateur et souligne la négociation et la porosité de leurs champs de compétence respectifs.
Detection of point landmarks in 3D medical images via phase congruency model
Authors: Ferrari Ricardo J. , Allaire Stéphane , Hope Andrew , Kim John , Jaffray David , Pekar Vladimir
Published: March 2011

This paper presents a novel technique for detection of point landmarks in volumetric medical images based on a three-dimensional (3D) Phase Congruency (PC) model. A bank of 3D log-Gabor filters is specially designed in the frequency domain and used to compute 3D energy maps, which are further combined to form the phase congruency measure. The PC measure is invariant to intensity variations and contrast resolution and provides a good indication of feature significance in an image. To detect significant 3D point landmarks, eigen-analysis of a 3×3 matrix of second-order PC moments, computed for each point in the image, is performed followed by local maxima detection. Two different application scenarios in radiation therapy planning of the head and neck anatomy are used to illustrate the feasibility and usefulness of the proposed method.
A two-step method for estimating QTL effects and positions in multi-marker analysis
Authors: MA WEIJUN , ZHOU YING , ZHANG SHUANGLIN
Published: March 2011

Quantitative trait is always controlled by multiple latent genetic loci, and genetic markers have been used to map quantitative trait loci (QTLs) auxiliarily. The method of multiple interval mapping (MIM) provides an appropriate way for mapping QTL using genetic makers. However, the computation in the MIM seems infeasible for a large number of marker intervals. Nowadays, the Dantzig selector (DS) method proves to be a more efficient method to estimate model effects in a linear model when the number of parameters is (much) larger than the sample size, which has not been applied to genetic mapping for QTL. In this paper, we developed a two-step method for mapping QTL based on the MIM, and we also illustrate the feasibility of adopting the DS to estimate marker or QTL effects. Simulation results showed that the proposed method performed satisfactorily well by comparisons with the existing MIM method, and the analysis to real data set also tested the practicability and efficiency of the DS method in genetic mapping.
Cryptosporidiumcell culture infectivity assay design
Authors: KING B. J. , KEEGAN A. R. , ROBINSON B. S. , MONIS P. T.
Published: March 2011

Members of the genusCryptosporidium, which cause the gastrointestinal disease cryptosporidiosis, still represent a significant cause of water-borne disease worldwide. While intensive efforts have been invested in the development of techniques for parasite culture,in vitrogrowth has been hampered by a number of factors including low levels of infectivity as well as delayed life-cycle development and poor synchronicity. In this study we examined factors affecting the timing of contact between excysted sporozoites and target host cells and the subsequent impact of this upon the establishment of infection. We demonstrate that excystation rate impacts upon establishment of infection and that in our standard assay format the majority of sporozoites are not close enough to the cell monolayer when they are released from the oocyst to successfully establish infection. However, this can be easily overcome by centrifugation of oocysts onto the cell monolayer, resulting in approximately 4-fold increases in sporozoite attachment and subsequent infection. We further demonstrate that excystation procedures can be tailored to control excystation rate to match the assay end purpose and that excystation rate can influence data interpretation. Finally, the addition of both a centrifugation and washing step post-sporozoite attachment may be appropriate when considering the design ofin vitroculture experiments for developmental analysis and stage-specific gene expression as this appears to increase the synchronicity of early developmental stages.
COMPARATIVE ANATOMY OF CALOLISIANTHUS SPECIES (GENTIANACEAE – HELIEAE) FROM BRAZIL: TAXONOMIC ASPECTS
Authors: Delgado M. N. , Azevedo A. A. , Silva L. C. , Valente G. E. , Kasuya M. C. M.
Published: March 2011

This work aims to characterise the morphology and anatomy of roots, stems and leaves of Calolisianthus species (Gentianaceae – Helieae) to assist in the taxonomy and understanding of some adaptive responses to high luminosity, prolonged water deficit and nutritional stress in their environment. Samples of Calolisianthus speciosus and C. pendulus were collected in campo rupestre (rocky land) and samples of C. amplissimus were collected in cerrado (savanna) areas in southeastern Brazil. The roots have a cortex with Arum-type arbuscular mycorrhizae. The three species have winged and square stems and in Calolisianthus amplissimus the stem is hollow. Calolisianthus pendulus and C. speciosus have a pair of conspicuous extrafloral nectaries at the leaf base, which are absent in C. amplissimus. Calolisianthus pendulus has a dorsiventral mesophyll and a round leaf margin with parenchymatic cells. Calolisianthus amplissimus has a homogeneous mesophyll and a leaf margin with collenchyma. Calolisianthus speciosus leaves have a homogeneous mesophyll and a margin with sclerenchyma and collenchyma. Our results demonstrate that some anatomical characters are useful for the identification of Calolisianthus species and might be used to elucidate evolutionary relationships among Calolisianthus and their adaptive responses.
REVISION OF PEDICULARIS SERIES TENUIROSTRES (OROBANCHACEAE)
Authors: Mill R. R.
Published: March 2011

Pedicularis ser. Tenuirostres Maxim. (Orobanchaceae) is demonstrated to be the correct name for the group usually referred to as P. ser. Pectinatae Prain. The series is here revised and 12 species are accepted. Its species are centred in the NW Himalaya, particularly Pakistan where there is much local infraspecific variation. Two species are excluded from the series: Pedicularis rhynchotricha P.C.Tsoong from China (Xizang) is placed in P. ser. Rhynchotrichae R.R.Mill and P. birmanica Bonati is confirmed as a member of P. ser. Brevifoliae (Prain) Bonati. One new species of Pedicularis ser. Tenuirostres is described: P. yamazakiana R.R.Mill from Nepal, which was formerly confused with P. pectinata subsp. palans Prain. Pedicularis jainii Aswal & Mehrotra is demonstrated to be a superfluous name for P. pyramidata Royle ex Benth. Pedicularis kashmiriana var. ornata Pennell is considered to be indistinguishable from P. pyramidata although P. kashmiriana var. kashmiriana is a recognisable taxon. An IUCN conservation assessment is proposed for Pedicularis rhynchotricha and for each taxon within P. ser. Tenuirostres.
The sensuous music aesthetics of the Middle Ages: the cases of Augustine, Jacques de Liège and Guido of Arezzo
Authors: Hentschel Frank
Published: March 2011

Using well-known texts by Augustine, Jacques de Liège and Guido of Arezzo, this article tries to show that, despite prior misunderstandings, medieval authors of music theory considered it a given that sensuous pleasure was the ultimate goal of music. Only by way of anachronistic readings of the sources have historians constructed an aesthetics that blended aesthetics with mathematical and theological ideas. A close reading of the sources, taking into account their cultural contexts, reveals the intentions of the authors that are at the root of the texts. Those intentions, it is argued, were not aesthetical, and any attempt to interpret them from such a perspective would be misleading. Yet careful consideration of those intentions opens the view for remarks that are truly aesthetical as well as for hints suggesting that aesthetical judgements, while self-evident, were not considered matters for written discourse but for orality.
Shape of things to come: factors affecting an ethnographic study in radiation therapy
Authors: Merchant Susan , Halkett Georgia , O’Connor Moira
Published: March 2011

The research process is a series of stages necessary to establish the integrity, value, and feasibility of a proposal. Part of the preparation is in understanding the process and factors that can contour a study. The aim of this paper is to outline the hidden factors that may be experienced when undertaking qualitative research. Although the participants are the main players of the study additional influences also require recognition to allow transparency of the project and the researcher’s stance. The guidance of university supervisors has the potential to influence the researcher’s perspective and the effectiveness of the study. Negotiation with clinical staff can add another dimension. Ethics committees are composed of individuals with varied expertise, bringing their points of view into the discussion and decision making, impacting further on the proposed research. It is important for medical radiations professionals who become involved in research to be aware of these factors and how they may influence a project and to acknowledge the impact of the perspectives of the researcher on the project. The significance of this paper is to provide novice researchers, an understanding of the influence, hidden factors play on the results of qualitative research with particular reference to ethnography.
A comparison of the implementation of Assertive Community Treatment in Melbourne, Australia and London, England
Authors: Harvey C. , Killaspy H. , Martino S. , White S. , Priebe S. , Wright C. , Johnson S.
Published: March 2011

Aims.

The efficacy of Assertive Community Treatment (ACT) is well established in the USA, and to a lesser extent in Australia, whereas UK studies suggest little advantage for ACT over usual care. Implementation of ACT varies and these differences may explain variability in reported efficacy. We aimed to investigate differences in ACT implementation between Melbourne, Australia and London, UK.

Methods.

In a cross-sectional survey, we investigated team organisation, staff and client characteristics from four Melbourne ACT teams using almost identical methods to the Pan London Assertive Outreach studies of 24 ACT teams.

Results.

Client characteristics, staff satisfaction and burnout were very similar. Three of four Melbourne teams made over 70% of client contacts ‘in vivo’ compared to only one-third of comparable London teams, although all teams were rated as ‘ACT-like’. Melbourne teams scored more highly on team approach. Three quarters of clients were admitted in the preceding 2 years but Melbourne clients had shorter stays.

Conclusions.

Differences in the implementation of ‘active components’ of home treatment models that have been associated with better client outcomes (home visiting, team approach) may explain international differences in ACT efficacy. Existing fidelity measures may not adequately weight these important elements of the model.
Nonchondritic 142Nd in suboceanic mantle peridotites
Authors: Cipriani Anna , Bonatti Enrico , Carlson Richard W.
Published: March 2011

The discovery that several solid Earth reservoirs have a superchondritic 142Nd/144Nd ratio led to the hypothesis that either the bulk silicate Earth is not chondritic or that a subchondritic reservoir lies hidden somewhere within the Earth's interior. One important reservoir, i.e., mid‐ocean ridge peridotites representing the main component of the upper oceanic mantle and the source of mid‐ocean ridge basalt, has never been tested for 142Nd/144Nd. We determined the 142Nd/144Nd ratio in clinopyroxene separated from two peridotites and a pyroxenite from the SW Indian Ridge and one peridotite from the northern Mid‐Atlantic Ridge. All samples analyzed have superchondritic 142Nd/144Nd ratios in line with mantle‐derived material measured to date, except for some ancient cratonic rocks.
Static and dynamic properties of one-dimensional linear chain of nanomagnets
Authors: Ding J. , Jain S. , Adeyeye A. O.
Published: March 2011

We have probed the dynamic and static behavior of one-dimensional linear chain of magnetostatically coupled Ni80Fe20 elements using ferromagnetic resonance (FMR) spectroscopy and magneto-optic Kerr effect measurement techniques. When compared with isolated elements of similar dimensions, we observed that both the FMR curves and magnetization reversal process of the coupled elements are strongly influenced by the strong magnetostatic interactions. We have modeled the effect of magnetostatic coupling, by extracting the demagnetizing factors for the isolated element from the experimental data using least square fitting method. Our experimental results are in good agreement with theory.