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Complex Configurations (complex + configuration)
Selected AbstractsSo near yet so far: blocked networks, global links and multiple exclusion in the German,Polish borderlandsGLOBAL NETWORKS, Issue 3 2006JÖRG DÜRRSCHMIDT We rarely consider borders and border regions. However, state borders provide a crucial component of a globalizing society in transition. Exhibiting a structural ambivalence, borders can be seedbeds of cosmopolitanism, sites of cultural closure, or often both simultaneously. To understand cross-border interaction we have to engage with a complex configuration of global and sub-global dynamics. In this article I argue that borders are revealing analytical tools that must be included in any grounded theory of global change. I draw on fieldwork conducted in the German-Polish border region, mostly in the German-Polish twin city Guben/Gubin. Here we are confronted with the simultaneous processes of globalization, European integration and post-socialist transformation. [source] A large-scale monitoring and measurement campaign for web services-based applicationsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 10 2010Riadh Ben Halima Abstract Web Services (WS) can be considered as the most influent enabling technology for the next generation of web applications. WS-based application providers will face challenging features related to nonfunctional properties in general and to performance and QoS in particular. Moreover, WS-based developers have to provide solutions to extend such applications with self-healing (SH) mechanisms as required for autonomic computing to face the complexity of interactions and to improve availability. Such solutions should be applicable when the components implementing SH mechanisms are deployed on both or only one platform on the WS providers and requesters sides depending on the deployment constraints. Associating application-specific performance requirements and monitoring-specific constraints will lead to complex configurations where fine tuning is needed to provide SH solutions. To contribute to enhancing the design and the assessment of such solutions for WS technology, we designed and implemented a monitoring and measurement framework, which is part of a larger Self-Healing Architectures (SHA) developed during the European WS-DIAMOND project. We implemented the Conference Management System (CMS), a real WS-based complex application. We achieved a large-scale experimentation campaign by deploying CMS on top of SHA on the French grid Grid5000. We experienced the problem as if we were a service provider who has to tune reconfiguration strategies. Our results are available on the web in a structured database for external use by the WS community. Copyright © 2010 John Wiley & Sons, Ltd. [source] Numerical determination of 3D temperature fields in steel jointsFIRE AND MATERIALS, Issue 2-4 2004Jean-Marc Franssen Abstract A numerical study was undertaken to investigate the temperature field in steel joints and to compare the temperatures in the joints with the temperatures of the adjacent steel members on the hypothesis that the thermal protection is the same on the joint and in the members. Very brief information is given on the numerical model, supplemented with parametric studies made in order to determine the required level of discretization in the time and in the space domain. A simplified assumption for representing the thermal insulation is also discussed and validated. Different numerical analyses are performed, with a variation of the following parameters: (i) type of joints, from very simple to more complex configurations, with welds and/or bolts, all of them representing joints between elements located in the same plane; (ii) unprotected joints or protected by one sprayed material; (iii) ISO, hydrocarbon or one natural fire scenario. The fact that the thermal attack from the fire might be less severe because the joints are usually located in the corner of the compartment is not taken into account. Copyright © 2004 John Wiley & Sons, Ltd. [source] Aerodynamic shape optimization on overset grids using the adjoint methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2010Wei Liao Abstract This paper deals with the use of the continuous adjoint equation for aerodynamic shape optimization of complex configurations with overset grids methods. While the use of overset grid eases the grid generation process, the non-trivial task of ensuring communication between overlapping grids needs careful attention. This need is effectively addressed by using a practically useful technique known as the implicit hole cutting (IHC) method. The method depends on a simple cell selection process based on the criterion of cell size, and all grid points including interior points and fringe points are treated indiscriminately in the computation of the flow field. This paper demonstrates the simplicity of the IHC method for the adjoint equation. Similar to the flow solver, the adjoint equations are solved on conventional point-matched and overlapped grids within a multi-block framework. Parallel computing with message passing interface is also used to improve the overall efficiency of the optimization process. The method is successfully demonstrated in several two- and a three-dimensional shape optimization cases for both external and internal flow problems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Sliding mesh algorithm for CFD analysis of helicopter rotor,fuselage aerodynamicsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 5 2008R. Steijl Abstract The study of rotor,fuselage interactional aerodynamics is central to the design and performance analysis of helicopters. However, regardless of its significance, rotor,fuselage aerodynamics has so far been addressed by very few authors. This is mainly due to the difficulties associated with both experimental and computational techniques when such complex configurations, rich in flow physics, are considered. In view of the above, the objective of this study is to develop computational tools suitable for rotor,fuselage engineering analysis based on computational fluid dynamics (CFD). To account for the relative motion between the fuselage and the rotor blades, the concept of sliding meshes is introduced. A sliding surface forms a boundary between a CFD mesh around the fuselage and a rotor-fixed CFD mesh which rotates to account for the movement of the rotor. The sliding surface allows communication between meshes. Meshes adjacent to the sliding surface do not necessarily have matching nodes or even the same number of cell faces. This poses a problem of interpolation, which should not introduce numerical artefacts in the solution and should have minimal effects on the overall solution quality. As an additional objective, the employed sliding mesh algorithms should have small CPU overhead. The sliding mesh methods developed for this work are demonstrated for both simple and complex cases with emphasis placed on the presentation of the inner workings of the developed algorithms. Copyright © 2008 John Wiley & Sons, Ltd. [source] Automatic unstructured surface mesh generation for complex configurationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2004Udo Tremel In this paper a new object-oriented (OO) approach is presented for automatic parallel advancing front based surface mesh generation and adaptive remeshing for complex configurations. Based on the ST++-system the advantages of the OO design and implementation compared to the traditional structural approach are described. Algorithmic enhancements to the advancing front method are explained, enabling a robust NURBS based triangulation process directly on B-rep CAD data. The message passing (MPI) parallelization strategy together with the achievable performance improvements are demonstrated. With the outlined parallel geometry analysis/rasterization a powerful method is described to derive automatically a well suited mesh size specification without any user-interaction from scratch. The application of this method to a complex ,real world' example finishes this paper. Copyright © 2004 John Wiley & Sons, Ltd. [source] Origins and Applications of London Dispersion Forces and Hamaker Constants in CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2000Roger H. French The London dispersion forces, along with the Debye and Keesom forces, constitute the long-range van der Waals forces. London's and Hamaker's work on the point-to-point dispersion interaction and Lifshitz's development of the continuum theory of dispersion are the foundations of our understanding of dispersion forces. Dispersion forces are present for all materials and are intrinsically related to the optical properties and the underlying interband electronic structures of materials. The force law scaling constant of the dispersion force, known as the Hamaker constant, can be determined from spectral or parametric optical properties of materials, combined with knowledge of the configuration of the materials. With recent access to new experimental and ab initio tools for determination of optical properties of materials, dispersion force research has new opportunities for detailed studies. Opportunities include development of improved index approximations and parametric representations of the optical properties for estimation of Hamaker constants. Expanded databases of London dispersion spectra of materials will permit accurate estimation of both nonretarded and retarded dispersion forces in complex configurations. Development of solutions for generalized multilayer configurations of materials are needed for the treatment of more-complex problems, such as graded interfaces. Dispersion forces can play a critical role in materials applications. Typically, they are a component with other forces in a force balance, and it is this balance that dictates the resulting behavior. The ubiquitous nature of the London dispersion forces makes them a factor in a wide spectrum of problems; they have been in evidence since the pioneering work of Young and Laplace on wetting, contact angles, and surface energies. Additional applications include the interparticle forces that can be measured by direct techniques, such as atomic force microscopy. London dispersion forces are important in both adhesion and in sintering, where the detailed shape at the crack tip and at the sintering neck can be controlled by the dispersion forces. Dispersion forces have an important role in the properties of numerous ceramics that contain intergranular films, and here the opportunity exists for the development of an integrated understanding of intergranular films that encompasses dispersion forces, segregation, multilayer adsorption, and structure. The intrinsic length scale at which there is a transition from the continuum perspective (dispersion forces) to the atomistic perspective (encompassing interatomic bonds) is critical in many materials problems, and the relationship of dispersion forces and intergranular films may represent an important opportunity to probe this topic. The London dispersion force is retarded at large separations, where the transit time of the electromagnetic interaction must be considered explicitly. Novel phenomena, such as equilibrium surficial films and bimodal wetting/dewetting, can result in materials systems when the characteristic wavelengths of the interatomic bonds and the physical interlayer thicknesses lead to a change in the sign of the dispersion force. Use of these novel phenomena in future materials applications provides interesting opportunities in materials design. [source] Probing Binding-Mode Diversity in Guanidinium,Oxoanion Host,Guest SystemsCHEMPHYSCHEM, Issue 6 2005Manal Haj-Zaroubi Dr. Abstract An attempt to experimentally estimate the role of binding-mode diversity (structural fuzziness) on the molecular recognition seen in the prominent guanidinium,oxoanion host,guest pair is described. The global heat response as measured by isothermal titration calorimetry in acetonitrile, which was obtained from the interaction of five different but structurally closely related guanidinium hosts with three rigid phosphinate guests of decreasing accessibility of their binding sites, is correlated to provide a trend analysis. All host,guest associations of 1:1 stoichiometry in this series are strongly enthalpy-driven. The change in complexation entropy can be related to the tightness of the mutual fit of the host,guest partners, which approaches a minimum limit and is interpreted as the unique lock-and-key binding mode. The ordinary host,guest complexation in this ensemble features substantial positive entropy changes that correlate inversely with the binding interface area. This finding excludes desolvation effects as the major cause of entropy production, and provides evidence for the existence of a broad variety of complex configurations rather than a single binding mode to represent the associated host,guest pair. This result bears on the molecular design of systems that vitally depend on structural fidelity, such as nanoassemblies or homogeneous catalysis. [source] | ||||||||||