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Solutions Available (solution + available)

Distribution by Scientific Domains

Engineering	42%
Physics and Astronomy	28%

Selected Abstracts

Method of fundamental solutions for partial-slip fibrous filtration flows

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2009
Shunliu Zhao
Abstract In this study a Stokeslet-based method of fundamental solutions (MFS) for two-dimensional low Reynolds number partial-slip flows has been developed. First, the flow past an infinitely long cylinder is selected as a benchmark. The numerical accuracy is investigated in terms of the location and the number of the Stokeslets. The benchmark study shows that the numerical accuracy increases when the Stokeslets are submerged deeper beneath the cylinder surface, as long as the formed linear system remains numerically solvable. The maximum submergence depth increases with the decrease in the number of Stokeslets. As a result, the numerical accuracy does not deteriorate with the dramatic decrease in the number of Stokeslets. A relatively small number of Stokeslets with a substantial submergence depth is thus chosen for modeling fibrous filtration flows. The developed methodology is further examined by application to Taylor,Couette flows. A good agreement between the numerical and analytical results is observed for no-slip and partial-slip boundary conditions. Next, the flow about a representative set of infinitely long cylindrical fibers confined between two planar walls is considered to represent the fibrous filter flow. The obtained flowfield and pressure drop agree very well with the experimental data for this setup of fibers. The developed MFS with submerged Stokeslets is then applied to partial-slip flows about fibers to investigate the slip effect at fiber,fluid interface on the pressure drop. The numerical results compare qualitatively with the analytical solution available for the limit case of infinite number of fibers. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Multivariable override control for systems with output and state constraints

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13-14 2004
Matthew C. Turner
An override control strategy for systems having limits on their outputs, states or linear combinations of the two, is discussed. The technique described is applicable to all nonlinear system-controller combinations which can be written in a certain linear closed-loop form. The discussion is first confined to the synthesis of a compensator where the limited states/outputs are perfectly known, and is then broadened to include an observer-based compensator for the case when these measurements are not directly available. It is shown that, although a form of ,separation principle' indeed holds for the observer-based problem, the type of solution available for this form of override control is not quite as strong as that available when an observer is not required. The results are illustrated using a simple multivariable example. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Progress in the Field of Electrospinning for Tissue Engineering Applications

ADVANCED MATERIALS, Issue 32-33 2009
Seema Agarwal
Abstract Electrospinning is an extremely promising method for the preparation of tissue engineering (TE) scaffolds. This technique provides nonwovens resembling in their fibrillar structures those of the extracellular matrix (ECM), and offering large surface areas, ease of functionalization for various purposes, and controllable mechanical properties. The recent developments toward large-scale productions combined with the simplicity of the process render this technique very attractive. Progress concerning the use of electrospinning for TE applications has advanced impressively. Different groups have tackled the problem of electrospinning for TE applications from different angles. Nowadays, electrospinning of the majority of biodegradable and biocompatible polymers, either synthetic or natural, for TE applications is straightforward. Different issues, such as cell penetration, incorporation of growth and differentiating factors, toxicity of solvents used, productivity, functional gradient, etc. are main points of current considerations. The progress in the use of electrospinning for TE applications is highlighted in this article with focus on major problems encountered and on various solutions available until now. [source]

Network modules help the identification of key transport routes, signaling pathways in cellular and other networks

ANNALEN DER PHYSIK, Issue 12 2009
R. Palotai
Abstract Complex systems are successfully reduced to interacting elements via the network concept. Transport plays a key role in the survival of networks , for example the specialized signaling cascades of cellular networks filter noise and efficiently adapt the network structure to new stimuli. However, our general understanding of transport mechanisms and signaling pathways in complex systems is yet limited. Here we summarize the key network structures involved in transport, list the solutions available to overloaded systems for relaxing their load and outline a possible method for the computational determination of signaling pathways. We highlight that in addition to hubs, bridges and the network skeleton, the overlapping modular structure is also essential in network transport. Path-lenghts in the module-space of the yeast protein-protein interaction network indicated that module-based paths may cross fewer modular boundaries than shortest paths. Moreover, by locating network elements in the space of overlapping network modules and evaluating their distance in this ,module space', it may be possible to approximate signaling pathways computationally, which, in turn could serve the identification of signaling pathways of complex systems. Our model may be applicable in a wide range of fields including traffic control or drug design. [source]

Spot modelling of the flare M4.5 dwarf YZ CMi

ASTRONOMISCHE NACHRICHTEN, Issue 6 2003
M. Zboril
Abstract We report on a photometric study of the flareM4.5 dwarf YZ CMi as based on photoelectric observations from the seasons 1972/73, 1979/80 and 1996/97. We suggest spot activity to explain the light and colour curves. Spots are generally 500K cooler than the surrounding photosphere and there are basically two solutions available for the observations: high latitude spot changing slightly basic properties such as radius and latitude or active near-equatorial (belt-like) centers represented by three spots. However, the activity centers changed in longitudes (,180°). The typical spot coverage (inclination i = 60°) is 10-15% and 5% for the season 1996/97 or ,25% for the stellar inclination i = 75°. As a by-product, V curve and (V-I) and (V-K) indexes turn out to be most promising in modelling of M-type stars as far as present calibrations are concerned. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Qualitätsprüfung für Energieausweis-Software

BAUPHYSIK, Issue 3 2009
Klaus Fehlauer Prof. Dr. Dr.
Energieeinsparung; Technische Regelwerke Abstract Nach der Einführung der Energieeinsparverordnung 2007 (EnEV 2007) beauftragte das Bundesamt für Bauwesen und Raumordnung (BBR) ein Forschungsprojekt, um die am Markt verfügbare Software zur EnEV 2007 einer Qualitätsprüfung zu unterziehen. Der Zweck des Projektes war die Prüfung hinsichtlich einer korrekten Nachweisführung und Energiepassausstellung sowie die Erarbeitung von Methoden zur Qualitätsprüfung und -sicherung mit dem Ziel, Transparenz bei den am Markt vorhandenen Softwarelösungen zu schaffen. Darüber hinaus sollte durch die Bereitstellung von Testmodulen die Möglichkeit geschaffen werden, vorhandene Softwareprodukte durch das Aufdecken von Mängeln stetig weiter zu entwickeln, um so die Qualität der Produkte auf hohem Niveau dauerhaft zu sichern. Es wurden 15 Softwareprogramme für Nichtwohngebäude und 13 Programme für Wohngebäude für die Bedarfsberechnung nach DIN 4108-6 und DIN V 4701-10 und für Verbrauchsausweiserstellung untersucht. Im Rahmen dieser Veröffentlichung wurden schwerpunktmäßig die Ergebnisse für die Bedarfsberechnungen auf Basis von DIN V 18599 für den Nichtwohngebäudebereich vorgestellt. Quality tests for Energy Passport software. Shortly after the introduction of the 2007 Building Energy Conservation Ordinance (EnEV 2007), the German Institute for Applied Information Technology in Construction (IAIB) was commissioned by the German Federal Office for Building and Regional Planning (BBR) to carry out quality tests for the EnEV 2007 software available on the market. The specified project aims were to check calculation and Energy Passport issuing procedures and the development of quality assurance methods with the aim of creating transparency regarding the software solutions available on the market. 15 software programs for office buildings and 13 software programs for residential buildings were examined with regard to the determination of energy demand according to DIN V 18599 and with regard to energy consumption. [source]

CLYTAIMESTRA'S NEGATIVES AND THE FINAL LINE OF AGAMEMNON

BULLETIN OF THE INSTITUTE OF CLASSICAL STUDIES, Issue 1 2004
Article first published online: 12 MAR 2010, JOHN LAVERY
Various supplements have been proposed. The paper restates the problems with the solutions available to date, and on the basis of the dramatic context, the structure of Clytaimestra's speeches in this section of the play and external evidence for Greek political vocabulary relevant to the political situation in Argos after the murder of Agamemnon offers new readings. [source]