bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topological index‐calculation of DAEs in circuit simulation
Authors: Tischendorf C. 
Published: December 2010

AbstractIn electric circuit simulation we are confronted with highly nonlinear DAEs with low smoothness properties. They may have index 2 but they do not belong to the class of Hessenberg form systems that are well understood. The classic and the charge‐oriented modified analysis are shown to lead to the same DAE‐index if the circuit models satisfy some natural assumptions.We present a topological criteria for calculating the index. This makes it possible to determine the index also for high‐dimensional circuit equation systems.
Optimal control of multibody systems in minimal coordinates
Authors: Von Stryk O. 
Published: December 2010

AbstractThe present paper deals with numerical methods for optimal control of mechanical multibody systems, such as many industrial robots, whose dynamical behavior can be described in minimal coordinates by a system of semi‐explicit second order differential equations: M(q(t))q̈(t) = u(t) + h(q(t), q̇(t), t), 0 ⩽ t ⩽ tf, where q denotes the state variables, u the control variables, and M(q) the positive definite mass matrix. Numerical methods are addressed for computing an approximation of the optimal control u*(t), 0 ⩽ t ⩽ tf, which steers the system from an initial to a final position minimizing a performance index, such as time or energy, subject to bounds or nonlinear constraints on q, q̇, and u. A method is investigated in more detail which is based on piecewise polynomial approximations of state variables and utilizes the structure of the dynamical equations as well as the structure in the resulting large and sparse, nonlinearly constrained optimization problems. Results for an industrial robot with six joints demonstrate that tailored optimization methods are very well suited for fast off‐line optimization of robot trajectories.
Some radial solutions of the equation Δu + K(|x|) u9 = 0 in ℛn
Authors: Vrdoljak B. 
Published: December 2010

AbstractThe present paper deals with the existence, behaviour and approximation of some positive radial solutions u (|x|) of the equation Δu + K (|x|) up = 0. The errors of the approximations for solutions u and the first derivative u′ are defined by the functions which can be sufficiently small A |x| ⩾ 1. The qualitative analysis theory and the topological retraction method are used.
Interpolation with tensor product splines subject to derivative constraints
Authors: Walther Marion 
Published: December 2010

AbstractIn this paper restricted interpolations of data sets (xi, yj, zi, j), i = 0,…, n, j = 0,…, m, on the rectangular grid Δ × Σ = {x0 <… < xn} × {yo <… < ym} are handled using biquadratic C1 and bicubic C2 splines on refined grids. The constraints on the first order derivatives are piecewise constant with respect to the original grid Δ × Σ. If the refinement of the grids are chosen adaptively, the existence of restricted interpolants can be assured for bounds strictly compatible with the data.
Preconditioning for special nonsymmetric systems
Authors: Zítko J. 
Published: December 2010

AbstractThe paper presents an algorithm for solving nonsymmetric linear systems arising from a two‐cyclic discretization of non‐selfadjoint two‐dimensional elliptic partial differential equations. The algorithm consists of a cyclic reduction repetition using red black ordering. The restarted and preconditioned GMRES method with pre‐iterations is used for solving the final reduced system. Numerical experiments have shown that this procedure accelerates the convergence several‐times.
On effective solution for some class of vector boundary Riemann problem and corresponding algebraic equations
Authors: Dmitriyeva I. 
Published: December 2010

AbstractThe special class of homogeneous vector boundary Riemann problem on the finite sequence of compact Riemann surfaces is investigated completely. Its coefficients are noncommutative permutation matrices of the arbitrary but not prime order, and boundary conditions are given on the system of open contours. The constructive algorithm and definite structure of the canonical solution matrix are obtained explicitly and present the considerable generalization of paper [1]. Simultaneously the corresponding class of algebraic equations for the appropriate covering surfaces is formed in obvious way too. The suggested applications concern mostly the solitary waves' theory and inverse scattering problem in particular (e. g. see [2]).
Semiaktive Dämpfung einer schwimmenden Offshorestruktur
Authors: Ehlers J. , Mahrenholtz O. 
Published: December 2010

AbstractSchwimmende Offshoreplattformen werden durch Seegang zu Bewegungen angeregt. Eine aktive Dämpfung der Bewegung ist aufgrund der erforderlichen Leistung nicht praktikabel. Hier wird eine semiaktive Dämpfung vorgeschlagen, der eine einfache, heuristisch gefundene Strategie zugrunde liegt. Die Wirksamkeit der semiaktiven Dämpfung wird durch Experimente im Wellenkanal demonstriert.
Uniqueness of solution of boundary value problems for the biharmonic equation
Authors: Eidelman S. 
Published: December 2010

AbstractIt is known that in order for a solution of a boundary value problems for elliptic equations in unbounded domains to be unique, it is necessary to impose additional constraints on the behavior, of solutions at infinity. Such constrains may be qualitatively different.In [1] it was noticed that the assumption that the solutions should be positive for sufficiently large arguments may also serve as a condition that guarantees the uniqueness of solutions. The present report explains an investigation of the conditions on boundary value problems whose fulfillment guarantees the validity of such uniqueness theorems for the biharmonic equation. For harmonic functions that satisfy the Dirichlet or Neumann boundary conditions, there are no such uniqueness theorems. But they can exist for simplest nonlocal boundary value problems for harmonic functions.
Hierarchic Models of Vibration Problems on Thin Domains
Authors: Gerdes K. , Schwab C. 
Published: December 2010

AbstractThe Helmholtz equation in a three‐dimensional plate is approximated by a hierarchy of two‐dimensional models. The necessity of including, besides polynomials, a certain number of trigonometric director functions into the Ansatz, in order to prevent pollution effects at high wave numbers is demonstrated for exponentially weighted norms.
Locally Supported Wavelets on the Sphere
Authors: Göttelmann Jochen 
Published: December 2010

AbstractWe construct explicitly wavelets on the sphere that provide a locally supported and stable basis for the Sobolev spaces H2,0 ⩽ s < 1. We get at hand at fast wavelet transform with almost optimal complexity. This basis can be easily implemented in numerical schemes. We apply the wavelet transform to singularity detection and data compression. This contribution summarizes the results of [1].
Einige Eigenschaften linearer und quasilinearer dynamischer Systeme mit rückläufigen Störungen nach dem Durchgang durch die Resonanzstellen
Authors: Hartung A. 
Published: December 2010

AbstractBetrachtet werden lineare und quasilineare dynamische Systeme mit Störungen, die als lineare Kombinationen der Funktionen sin und cos von Polynome dargestellt sind. Diese Modelle verwendet man zum Durchgang durch die Resonanzstellen. Es werden die Eigenschaften beschränkter Lösungen von o. g. Systemen untersucht, darunter der Art deren Strebung gegen null, wenn die Zeit gegen unendlich geht.
Anwendung eines RSM gestützten stochastischen Gradientenverfahrens in der stochastischen Strukturoptimierung flexibler Roboter
Authors: Haubach‐Lippmann C. 
Published: December 2010

AbstractIn vielen Problemstellungen der stochastischen Strukturoptimierung ist es von besonderem Interesse, die Zuverlässigkeit einer Struktur zu maximieren, oder mit anderen Worten die Wahrscheinlichkeit des Versagens zu minimieren. Das robuste Design flexibler Roboterstrukturen ist eine aktuelle Anwendung hierfür. Anhand eines Roboterbeispiels wird die Anwendbarkeit eines stochastischen Gradienten‐Verfahrens mit adaptiver Schrittweitensteuerung, dessen Suchrichtungen durch die response surface method (RSM) bestimmt werden, untersucht.
Eine Finite Element Schalenformulierung ohne Rotationsfreiheitsgrade
Authors: Hauptmann R. , Schweizerhof K. 
Published: December 2010

AbstractVielen effizienten Schalenelementen für FE‐Anwendungen liegt das Degenerationskonzept zugrunde, dessen wesentliche Merkmale eine Kinematik mit Rotationsfreiheitsgraden und die Beschränkung auf einen ebenen Spannungszustand sind. Somit erfordern bereits geometrisch nichtlineare Berechnungen aufgrund der Verdrehungsfreiheitsgrade relativ aufwendige Formulierungen, die bei materiell nichtlinearen Berechnungen durch die Forderung nach einem ebenen Spannungszustand wesentlich komplexer werden. Ziel der Studie ist, eine Schalenformulierung vorzustellen, die diese nicht Nachteile aufweist.
Stability for ROW‐methods adapted to circuit simulation
Authors: Hoschek Markus 
Published: December 2010

AbstractAutomatic generation and numerical integration of network equations are the core of industrial TCAD packages for analog simulation of highly integrated circuits [1]. Many packages supply the Jacobian with every function evaluation at very low additional costs: it is about only 1.4 times more expensive to evaluate both right‐hand side and Jacobian than right‐hand side alone.In this paper we discuss four different approaches to use the cheap Jacobian information within a ROW‐type integration scheme, mainly with respect to stability.
Multigrid Schur Complement Preconditioning in BE‐DD Methods
Authors: Kuhn M. 
Published: December 2010

AbstractWe consider Domain Decomposition (DD) Boundary Element (BE) equations and analyze a multigrid preconditioner, derived from the hypersingular operator, for the Schur complement. The robustness of the preconditioner with respect to the number of subdomains is being investigated.
Unbounded Solutions in Non‐Smooth Dynamical Systems at Resonance
Authors: Kunze M. 
Published: December 2010

AbstractWe consider periodically forced non‐smooth dynamical systems at resonance, described by differential inclusions, and we show that analogously to the case of ODEs all solutions are unbounded in the (x)‐phase plane, if the first Fourier coefficient of the forcing is large compared to a certain quantity related to the nonlinearity.
The Central Two‐Point Connection Problem in Quantum Mechanics
Authors: Lay W. 
Published: December 2010

AbstractExponentially small effects in physical systems have attained much attention in recent literature. They not only are difficult to understand from the viewpoint of classical (Poincaré) asymptotics but also are hard to calculate. In the following we give a brief account of an approach to the central two‐point connection problem of the triconfluent case of Heun's differential equation. It does not seem to be recognized that the solution of this problem opens the possibility to calculate exponentially small effects. A famous example in mathematical physics is the effect of avoided crossings of eigenvalue curves in the case of the double‐well quartic oscillator in quantum mechanics. On the basis of the above‐mentioned singularity‐analytical approach we have carried out the numerical calculation of the effect with a rather low calculatory effort.
Zur Existenz von Spektrallücken bei periodischen Operatoren vom Divergenztyp
Authors: Lienau K. 
Published: December 2010

AbstractWir betrachten Spektraleigenschaften periodischer Divergenztyp‐Operatoren‐Δ· A(x)Δ mit elliptischer Koeffizientenmatrix A(x). Das Hauptinteresse gilt hierbei der Existenz von Spektrallücken bei “typischen” Operatoren, also im generischen Fall. Eine ausführliche Darstellung findet sich in der Arbeit von R. Hempel und K. Lienau [2], in der auch weiterführende Resultate zur Zustandsdichte der betrachteten Operatoren vorgestellt werden.
Optimierung der elastisch gebetteten Träger
Authors: Mikulski L. 
Published: December 2010

AbstractEs werden folgende Optimalsteuerungsprobleme gelöst: Minimierung der maximalen Verschiebung und optimale verteilung der zusätzlichen Belastung. Die zugehörige Optimalsteuerungsaufgabe führt auf ein Mehrpunktrandwertproblem. Für die Lösung der gestellten Aufgaben, steht ein leistungsfähiges Verfahren zur Verfügung, das auf der Mehrzielmethode beruht. Als Ergebnis erhält man einen Träger mit optimalem Querschnittsverlauf sowie optimaler Lastverteilung, dessen maximale Verschiebung bis zu 40% geringer ist.
On robustness of nonlinear systems
Authors: Paice A. , Wirth F. 
Published: December 2010

AbstractWe study the problem of measuring the robustness of stability for a perturbed discrete time nonlinear system. Various stability radii are introduced and their values for the nonlinear system and its linearization are compared. For the time‐invariant case the nonlinear and the linear version of the stability radius coincide generically. In the case of time‐varying perturbations we may again use the linearization to obtain genericity results on the nonlinear stability radius.
Computing Multiple Turning Points
Authors: Pönisch G. , Schnabel U. , Schwetlick H. 
Published: December 2010

AbstractA point (x*,λ*) is called a turning point of multiplicity p ≥ 1 of the nonlinear system F(x,δ) = 0, F:ℛn × IR1 → ℛn if rank δx F(x*, λ*) = n ‐ 1, rank [δx F(x*, λ*)|λ F (x*, λ*)] = n, and if the Ljapunov‐Schmidt reduced function has the normal form g(ζ,μ) = ζp+1 ± μ, g : ℛ1 × ℛ1 → ℛ1. A minimally extended system F(x,λ) = 0, H(x, λ) = 0 is proposed for defining turning points of multiplicity p, where H : ℛn × ℛ1 → ℛ1 is a scalar function which is related to the p‐th order partial derivatives of g with respect to ζ. When F depends on m ⩽ p ‐‐ 1 additional parameters α ϵ ℛm, the system F(x,λ,α) = 0 can be inflated by m + 1 scalar equations H1 (x,λ, α) = 0,…, Hm+1 (x,λ, α) = 0. The functions H1, : ℛn × ℛ1 × ℛm × ℛ1 depend on certain partial derivatives of g with respect to ζ where Hm+1 corresponds to H in the case m = 0. The regular solution (x*, λ*, α*) of the extended system of n+m+1 equations delivers the desired turning point (x*, λ*) as first part. For numerically solving these systems, two‐stage Newton‐type methods are proposed. They require to compute higher order partial derivatives of F with respect to low dimensional subspaces as well as derivatives of implicitly defined related functions. Both tasks are realized via automatic differentiation. The behavior of the algorithms has been tested in case of turning points of multiplicity p = 2, 3.
Nonlinear Extensions of Classical Controllers Using Symbolic Computation Techniques: A Dynamical Systems Unifying Approach
Authors: Rodriguez‐Millan Jesus , Bokor Jozsef 
Published: December 2010

AbstractIn previous works we reported the development of symbolic computation tools to automate the design of nonlinear state feedback controllers [1], nonlinear PID controllers [2], nonlinear lag‐lead compensators [3], and nonlinear obsevers [4] using the extended linearization method [5]. In this paper we show that a careful analysis of the state variables representation of these classical controllers indicates that all of them are particular cases of the nonlinear extension of a mth order linear filter, consisting of a kth order input derivative operator followed by an output mth order linear dynamical system. Using this two blocks decomposition approach, the design of nonlinear extensions of nth order controllers can be decomposed into two independent subalgorithms: a kth order PD controller algorithm, and a mth order state vector feedback algorithm. Hence, an appropriate, assembly of our symbolic computation tools NL Feedback and NLPID could, in principle, allow to use the extended linearization method to synthesize nonlinear extension of arbitrary nth order linear filter (controllers).
Bounds on Eigenvalues of Interval Matrices
Authors: Rohn J. 
Published: December 2010

AbstractWe describe a rectangle in the complex plane enclosing all eigenvalues of an interval matrix. We give theoretical bounds (Theorem 1) that are exact for symmetric or skew‐symmetric matrices, and practical bounds (Theorem 2) requiring evaluation of 4 minimal or maximal eigenvalues and 2 spectral radii of symmetric matrices.
First captive breeding of the imperial parrot (Amazona imperialis)
Authors: Reillo Paul R. , Durand, Stephen , Burton Minchinton 
Published: December 2010

AbstractWe describe the rearing and development of the first imperial parrot (Amazona imperialis) hatched and raised in captivity. A single egg was hen‐incubated for 28 days, and the chick was parent‐fed for ∼14 days, after which it was removed for hand‐rearing. Similar to wild, parent‐reared imperial nestlings, the chick developed fully within 12 weeks, weaning at 540 g body weight. Endangered and endemic to Dominica, the imperial is a vital flagship for oceanic rainforest conservation. Chronicling the neonatal development of A. imperialis helps illuminate the natural history of this enigmatic species, whose secretive nesting habits and low population density have frustrated a detailed understanding of its ecology and reproduction. Zoo Biol 30:328–341, 2011. © 2010 Wiley‐Liss, Inc.
Observation of reproductive cycle of female yellow‐margined box turtle (Cuora flavomarginata) using radiography and ultrasonography
Authors: Chen Ting‐Yu , Lee Yen‐Tao , Chi Chau‐Hwa 
Published: December 2010

AbstractThis study presents a combination of radiography and ultrasonography to observe the reproductive cycle of 24 captive female yellow‐margined box turtles in Taiwan. Radiography was mainly used to monitor clutch size, whereas ultrasonography was applied to detect changes in the follicles throughout the year. The observation of the 24 female turtles was performed from April 2007 to June 2008. Their average carapace length was 16.62 ± 1.66 cm and their average body weight was 812 ± 164.98 g. The mean clutch size was three (87 eggs/29 clutches) and the reproductive frequency was 95.83% (23/24). Double clutches were detected in 79.2%, and 20.8% had single clutches. Ovulation occurred from March through August, and the average follicular diameter was 2.16 ± 0.18 cm. Follicles entered the latent period in October (at 1.54 ± 0.26 cm), and vitellogenesis of the next reproductive cycle began in November. Using radiography, the eggshell could be detected on the ninth day after ovulation. The average period of the single clutch group was 6.9 weeks (range 5.1–8.5 weeks). In the double clutch group, the average period of the first clutch was 5.5 weeks (range 4–7.8 weeks) and that of the second clutch was 5.2 weeks (range 4–7.8 weeks). This study has advanced the understanding of reproductive physiology of yellow‐margined box turtle and established a valuable and practical model for comparative study of the reproductive physiology of other chelonians. Zoo Biol 30:689–698, 2011. © 2010 Wiley Periodicals, Inc.
Laparoscopic Repeat Resection of Recurrent Hepatocellular Carcinoma
Authors: Hu Minggen , Zhao Guodong , Xu Dabin , Liu Rong 
Published: December 2010

AbstractBackgroundThe present study was designed to explore the safety and feasibility of laparoscopic re‐resection of recurrent liver tumors.MethodsAmong 120 hepatocellular carcinoma patients who received laparoscopic hepatectomy, six were carefully selected to receive laparoscopic re‐resection. Surgical indications were evaluated by specific selection criteria for tumor location, size, metastases, vessel invasion, and liver function. Four patients received laparoscopic partial hepatectomy, and two received laparoscopic anatomical left lateral lobe resection. Results were analyzed retrospectively.ResultsThe six surgeries (four laparoscopic partial hepatectomies, two laparoscopic anatomical left lateral lobe resections) were successfully performed with no intraoperative complications. Mean operative time was 140.83 ± 35.69 min, mean blood loss was 283.33 ± 256.25 ml, and mean hospital stay was 5.67 ± 1.63 days.ConclusionsOur experience with carefully selected cases meeting specific criteria suggests that laparoscopic hepatic re‐resection is a safe, feasible procedure that may offer multiple benefits for treating recurrent hepatocellular carcinoma.
Endarterectomy of the Aneurysm Sac in Open Abdominal Aortic Aneurysm Repair Reduces Perigraft Seroma and Improves Graft Incorporation
Authors: Wolff Thomas , Koller Michael T. , Eugster Thomas , Rouden Christophe , Marti Regula , Gürke Lorenz , Stierli Peter 
Published: December 2010

AbstractBackgroundFluid around the graft in the original aneurysm sac after open abdominal aortic aneurysm (AAA) repair is a poorly researched phenomenon. If large, such perigraft seroma can cause symptoms of compression, and cases of rupture have even been described. We assessed whether endarterectomy of the aneurysm sac reduces the incidence of perigraft fluid and improves graft incorporation.Design and methodsStarting in July 2005, all patients with elective open AAA repair were alternately treated either with conventional thrombectomy or thrombectomy plus endarterectomy of the aneurysm sac. All patients were treated with a polytetrafluoroethylene (PTFE) graft. The maximum axial width of the perigraft fluid collection was measured on computed tomography (CT) scans 1 year after operation.ResultsThe CT scans of 115 patients were available; 56 had endarterectomy of the aneurysm sac and 59 did not. Fluid collections were significantly smaller in patients with endarterectomy (median width 4.0 versus 8.0 mm; P = 0.0001). Eight patients with endarterectomy had a fluid collection wider than 10 mm compared to 28 patients without endarterectomy (OR 0.18, 95% CI 0.07–0.46). After endarterectomy, 17 patients had radiological signs of complete graft incorporation in comparison to only 6 patients without endarterectomy (OR 3.85, 95% CI 1.39–10.66). No patients were symptomatic or reoperated for perigraft seroma.ConclusionsEndarterectomy of the aneurysm sac in open AAA repair appears to improve graft incorporation. The high rate of asymptomatic perigraft seroma is surprising, and its clinical significance is unknown. Ultrafiltration of PTFE grafts may be an underlying mechanism.
Hyperbaric Oxygen Therapy: Solution for Difficult to Heal Acute Wounds? Systematic Review
Authors: Eskes Anne M. , Ubbink Dirk T. , Lubbers Maarten J. , Lucas Cees , Vermeulen Hester 
Published: December 2010

AbstractBackgroundHyperbaric oxygen therapy (HBOT) is used to treat various wound types. However, the possible beneficial and harmful effects of HBOT for acute wounds are unclear.MethodsWe undertook a systematic review to evaluate the effectiveness of HBOT compared to other interventions on wound healing and adverse effects in patients with acute wounds. To detect all available randomized controlled trials (RCTs) we searched five relevant databases up to March 2010. Trial selection, quality assessment, data extraction, and data synthesis were conducted by two of the authors independently.ResultsWe included five trials, totaling 360 patients. These trials, with some methodologic flaws, included different kinds of wound and focused on different outcome parameters, which prohibited meta‐analysis. A French trial (n = 36 patients) reported that significantly more crush wounds healed with HBOT than with sham HBOT [relative risk (RR) 1.70, 95% confidence interval (CI) 1.11–2.61]. Moreover, there were significantly fewer additional surgical procedures required with HBOT (RR 1.60, 95% CI 1.03–2.50), and there was significantly less tissue necrosis (RR 1.70, 95% CI 1.11–2.61). In one of two American trials (n = 141) burn wounds healed significantly quicker with HBOT (P < 0.005) than with routine burn care. A British trial (n = 48) compared HBOT with usual care. HBOT resulted in a significantly higher percentage of healthy graft area in split skin grafts (RR 3.50, 95% CI 1.35–9.11). In a Chinese trial (n = 145) HBOT did not significantly improve flap survival in patients with limb skin defects.ConclusionsHBOT, if readily available, appears effective for the management of acute, difficult to heal wounds.