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Linear Approach (linear + approach)

Distribution by Scientific Domains

Engineering	66%

Selected Abstracts

A new second-moment closure approach for turbulent swirling confined flows

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2003
Pisi Lu
Abstract An improved anisotropic model for the dissipation rate,,,of the turbulent kinetic energy (k), to be used together with a non-linear pressure-strain correlations model, is proposed. Experimental data from the open literature for two confined turbulent swirling flows are used to assess the performance of the proposed model in comparison to the standard , transport equation and to a linear approach to model the pressure-strain term that appears in the exact equations for the Reynolds-stress tensor. For the less strongly swirling flow the predictions show much more sensitivity to the ,transport equation than to the pressure-strain model. In opposition, for the more strongly swirling flow, the results show that the predictions are much sensitive to the pressure-strain model. Nevertheless, the improved ,transport equation together with the non-linear pressure strain model yield predictions in good agreement with experiments in both studied cases. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Amplitude estimation for near-sinusoidal oscillators by using a modified Barkhausen criterion

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2005
H. Jardón-Aguilar
Abstract By using an approach based on the Taylor/Volterra series, nonlinear amplifier characteristics can be introduced into the Barkhausen criterion in order to estimate the amplitude for near-sinusoidal oscillators. The characteristic equation is similar to the 1st -order determining equation obtained by Chua. This new method includes all desirable features of Chua's equation and lets us generalize the linear approach directly to a nonlinear one without losing the mathematical simplicity of the Barkhausen criterion. It also allows us to determine the oscillation amplitude with a desired accuracy. Moreover, this method investigates the influence of the feedback factor and the voltage supply on the oscillation amplitude. Employing only the 3rd -order nonlinearity of the amplifying element, the amplitude of the oscillation predicted by the modified Barkhausen criterion was compared to the one estimated using the transient analysis of SPICE, the harmonic balance analysis of Serenade, and by measurements. The amplitudes obtained by these four approaches for several feedback factors and supply voltages are in good agreement. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]

Kalevala or Keats: poetic traditions as a model for multidisciplinary miscommunication and team splitting

JOURNAL OF PSYCHIATRIC & MENTAL HEALTH NURSING, Issue 7 2008
D. DODWELL
Attention is drawn to the oral tradition in poetry and some ways in which it differs from written, literary poetry. Some of these differences mirror differences between the oral communication typical of a psychiatric ward nursing handover and the writing-based communication styles of psychiatrists. In particular, the oral tradition tends to involve an interactive and participatory style, stewardship (rather than authorship) of the message, a less linear approach to time and valuing the use of familiar formulae. Neither style is intrinsically superior or inferior. The two styles have significant differences in context, intent and rules (i.e. in linguistic ,pragmatics'). In mental health practice, the apparently shared vocabulary and setting conceals these differences. The fact that these variations are hidden increases the risks of miscommunication and of team splitting. The use of an analogy from poetry is intended to make the differences more explicit, and thus generate awareness, discussion and problem solving. [source]

Nonlinear Model Order Reduction in Nanoelectronics: Combination of POD and TPWL

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008
T. Bechtold
In this paper we demonstrate model order reduction of a nonlinear academic model of an inverter chain. Two reduction methods, which are suitable for nonlinear differential algebraic equation systems are combined, the trajectory piecewise linear approach and the proper orthogonal decomposition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Nichtlinearer Bettungsansatz von Besler bei Baugrubenwänden

BAUTECHNIK, Issue 9 2005
Achim Hettler Prof. Dr.-Ing. habil.
Im Beitrag wird am Beispiel einer einfach gestützten Wand untersucht, wie im Sinne eines verbesserten Gebrauchstauglichkeitsnachweises das Verhalten des Wandfußes wirklichkeitsnah erfaßt werden kann. Grundlage ist der nichtlineare Bettungsansatz von Besler. Schwerpunkte der Untersuchungen sind die programmtechnische Umsetzung sowie der Einfluß der Biegesteifigkeit und der Vorbelastung aus dem Gewicht des Aushubs auf die Verschiebungen. Aufbauend auf den Ergebnissen werden Empfehlungen für die Anwendung in der Praxis gegeben. Besler's nonlinear subgrade reaction approach for excavation walls. It is investigated how the displacements of the foot of the wall in service states can be described close to the real behaviour. Thereby Besler's non linear approach for the subgrade reaction is used. The main points of the paper are the numerical implementation and the influence of the flexibility and preloading by the weight of the excavation on the displacements. Finally recommendations are given for the use in practice. [source]

Linear models for minimizing misclassification costs in bankruptcy prediction

INTELLIGENT SYSTEMS IN ACCOUNTING, FINANCE & MANAGEMENT, Issue 3 2001
Sudhir Nanda
This paper illustrates how a misclassification cost matrix can be incorporated into an evolutionary classification system for bankruptcy prediction. Most classification systems for predicting bankruptcy have attempted to minimize misclassifications. The minimizing misclassification approach assumes that Type I and Type II error costs for misclassifications are equal. There is evidence that these costs are not equal and incorporating costs into the classification systems can lead to better and more desirable results. In this paper, we use the principles of evolution to develop and test a genetic algorithm (GA) based approach that incorporates the asymmetric Type I and Type II error costs. Using simulated and real-life bankruptcy data, we compare the results of our proposed approach with three linear approaches: statistical linear discriminant analysis (LDA), a goal programming approach, and a GA-based classification approach that does not incorporate the asymmetric misclassification costs. Our results indicate that the proposed approach, incorporating Type I and Type II error costs, results in lower misclassification costs when compared to LDA and GA approaches that do not incorporate misclassification costs. Copyright © 2001 John Wiley & Sons, Ltd. [source]