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Spatial Dimensions (spatial + dimension)
Selected AbstractsNovel Imaging Analysis System to Measure the Spatial Dimension of Engineered Tissue ConstructARTIFICIAL ORGANS, Issue 2 2010Kyoung-Hwan Choi Abstract The measurement of the spatial dimensions of tissue-engineered constructs is very important for their clinical applications. In this study, a novel method to measure the volume of tissue-engineered constructs was developed using iterative mathematical computations. The method measures and analyzes three-dimensional (3D) parameters of a construct to estimate its actual volume using a sequence of software-based mathematical algorithms. The mathematical algorithm is composed of two stages: the shape extraction and the determination of volume. The shape extraction utilized 3D images of a construct: length, width, and thickness, captured by a high-quality camera with charge coupled device. The surface of the 3D images was then divided into fine sections. The area of each section was measured and combined to obtain the total surface area. The 3D volume of the target construct was then mathematically obtained using its total surface area and thickness. The accuracy of the measurement method was verified by comparing the results with those obtained from the hydrostatic weighing method (Korea Research Institute of Standards and Science [KRISS], Korea). The mean difference in volume between two methods was 0.0313 ± 0.0003% (n = 5, P = 0.523) with no significant statistical difference. In conclusion, our image-based spatial measurement system is a reliable and easy method to obtain an accurate 3D volume of a tissue-engineered construct. [source] Building the Other, Constructing Ourselves: Spatial Dimensions of International Humanitarian ResponseINTERNATIONAL POLITICAL SOCIOLOGY, Issue 3 2008Lisa Smirl Humanitarian reconstruction after a large-scale natural disaster has become a key site of international politics; a site where global assumptions, relationships, and responsibilities are negotiated, solidified and questioned. While post-crisis response strategies and institutional practices have strong spatial and material characteristics, these are rarely considered as significant,either to the reconstruction effort, or to international politics more generally. This article identifies and examines the "auxiliary space" created by the everyday practices of international aid workers and asks whether its effects may lead to unanticipated and potentially transformative outcomes not only for the reconstruction effort, but also for global North-South relations at large. The article concludes that post-crisis reconstruction sites may offer both cautionary and emancipatory potential for the evolution of international relations. [source] A green to red photoconvertible protein as an analyzing tool for early vertebrate developmentDEVELOPMENTAL DYNAMICS, Issue 2 2007Stephan A. Wacker Abstract Lineage labeling is one of the most important techniques in developmental biology. Most recently, a set of photoactivatable fluorescent proteins originating from marine cnidarians became available. Here, we introduce the application of the green to red photoconvertible protein EosFP as a novel technique to analyze early vertebrate development. Both injection of EosFP mRNA and purified, recombinant EosFP followed by a light-driven green to red conversion allow lineage labeling in virtually any temporal and spatial dimension during embryonic development for at least 2 weeks. Specific staining of cells from nonsurface layers is greatly facilitated by light-driven conversion of EosFP compared with traditional methods. Therefore, green to red photoactivatable proteins promise to be a powerful tool with the potential to satisfy the increasing demand for methods enabling detailed phenotypical analyses after manipulations of morphogenetic events, gene expression, or signal transduction. Developmental Dynamics 236:473,480, 2007. © 2006 Wiley-Liss, Inc. [source] A Surface-Based Approach to Measuring Spatial SegregationGEOGRAPHICAL ANALYSIS, Issue 2 2007David O'Sullivan Quantitative indices of residential segregation have been with us for half a century, but suffer significant limitations. While useful for comparison among regions, summary indices fail to reveal spatial aspects of segregation. Such measures generally consider only the population mix within zones, not between them. Zone boundaries are treated as impenetrable barriers to interaction between population subgroups, so that measurement of segregation is constrained by the zoning system, which bears no necessary relation to interaction among population subgroups. A segregation measurement approach less constrained by the chosen zoning system, which enables visualization of segregation levels at the local scale and accounts for the spatial dimension of segregation, is required. We propose a kernel density estimation approach to model spatial aspects of segregation. This provides an explicitly geographical framework for modeling and visualizing local spatial segregation. The density estimation approach lends itself to development of an index of spatial segregation with the advantage of functional compatibility with the most widely used index of segregation (the dissimilarity index D). We provide a short review of the literature on measuring segregation, briefly describe the kernel density estimation method, and illustrate how the method can be used for measuring segregation. Examples using a simulated landscape and two empirical cases in Washington, DC and Philadelphia, PA are presented. [source] Seismic data reconstruction using multidimensional prediction filtersGEOPHYSICAL PROSPECTING, Issue 2 2010M. Naghizadeh ABSTRACT In this paper we discuss a beyond-alias multidimensional implementation of the multi-step autoregressive reconstruction algorithm for data with missing spatial samples. The multi-step autoregressive method is summarized as follows: vital low-frequency information is first regularized adopting a Fourier based method (minimum weighted norm interpolation); the reconstructed data are then used to estimate prediction filters that are used to interpolate higher frequencies. This article discusses the implementation of the multi-step autoregressive method to data with more than one spatial dimension. Synthetic and real data examples are used to examine the performance of the proposed method. Field data are used to illustrate the applicability of multidimensional multi-step autoregressive operators for regularization of seismic data. [source] Finite element analyses of layered visco-elastic system under vertical circular loadingINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2008Q. Xu Abstract Analyses for the response of a linear visco-elastic system subjected to axi-symmetric vertical circular loading are presented. Hankel transforms with respect to the radial spatial coordinate are used to reduce the three-dimensional problem to that involving only a single spatial dimension, which is then discretized using the finite element method. Three techniques are employed to handle the time factor in the visco-elastic material: (i) direct time integration; (ii) Fourier transforms; and (iii) Laplace transforms. These methods are compared and evaluated through their numerical results. Copyright © 2007 John Wiley & Sons, Ltd. [source] Reduced-order modeling of parameterized PDEs using time,space-parameter principal component analysis,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 8 2009C. Audouze Abstract This paper presents a methodology for constructing low-order surrogate models of finite element/finite volume discrete solutions of parameterized steady-state partial differential equations. The construction of proper orthogonal decomposition modes in both physical space and parameter space allows us to represent high-dimensional discrete solutions using only a few coefficients. An incremental greedy approach is developed for efficiently tackling problems with high-dimensional parameter spaces. For numerical experiments and validation, several non-linear steady-state convection,diffusion,reaction problems are considered: first in one spatial dimension with two parameters, and then in two spatial dimensions with two and five parameters. In the two-dimensional spatial case with two parameters, it is shown that a 7 × 7 coefficient matrix is sufficient to accurately reproduce the expected solution, while in the five parameters problem, a 13 × 6 coefficient matrix is shown to reproduce the solution with sufficient accuracy. The proposed methodology is expected to find applications to parameter variation studies, uncertainty analysis, inverse problems and optimal design. Copyright © 2009 John Wiley & Sons, Ltd. [source] Time-steppers and ,coarse' control of distributed microscopic processesINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2004Antonios Armaou Abstract We present an equation-free multiscale computational framework for the design of ,coarse' controllers for complex spatially distributed processes described by microscopic/mesoscopic evolution rules. We illustrate this framework by designing discrete-time, coarse linear controllers for a Lattice,Boltzmann (LB) scheme modelling a reaction,diffusion process (a kinetic-theory based realization of the FitzHugh,Nagumo equation dynamics in one spatial dimension). Short ,bursts' of appropriately initialized simulation of the LB model are used to extract the stationary states (stable and unstable) and to estimate the information required to design the coarse controller (e.g. the action of the coarse slow Jacobian of the process). Copyright © 2004 John Wiley & Sons, Ltd. [source] The reform of palaeontology and the rise of biogeography , 25 years after ,ontogeny, phylogeny, paleontology and the biogenetic law' (Nelson, 1978)JOURNAL OF BIOGEOGRAPHY, Issue 5 2004David M. Williams Abstract Aim, To document the historical development of cladistics and the roles palaeontology and biogeography played in establishing coherent concepts of phylogenetic relationships focusing on some aspects of the contributions of Gareth Nelson. Conclusions, Nelson's reformulation of the threefold parallelism provides a rationale for investigating phylogeny, replacing the central role palaeontology once played with biogeography, adding a spatial dimension to the concept of phylogeny. This approach to phylogeny replaces the old ,transformationist' view with the cladistic view, the latter dependent on discovering relationships among taxa. Numerical phylogenetic methods are inherently ,transformationist' and have replaced stratigraphy as the key to phylogenetic relationships. Numerical methods in systematics and biogeography are inherently transformational and suffer the same problems as the old palaeontology. [source] THE IMPACTS OF TRANSPORTATION INFRASTRUCTURE ON PROPERTY VALUES: A HIGHER-ORDER SPATIAL ECONOMETRICS APPROACHJOURNAL OF REGIONAL SCIENCE, Issue 3 2007Jeffrey P. Cohen ABSTRACT We evaluate the impacts of enhanced transportation systems on property values for U.S. manufacturing firms, allowing for higher-order spatial error correlation. We use a state-level model of production cost and input demand that recognizes the productive contribution of public transportation infrastructure stocks. Our findings include significant impacts on property shadow values and input composition from both public highway and airport investment. We also find that these effects have a spatial dimension that depends on the proximity of the transport system; at least one and as many as three spatial error lags are significant in our estimating equations. Further, recognizing production growth from transportation system improvements augments the associated incentives for private capital investment. [source] Efficiency-based h - and hp -refinement strategies for finite element methodsNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 2-3 2008H. De Sterck Abstract Two efficiency-based grid refinement strategies are investigated for adaptive finite element solution of partial differential equations. In each refinement step, the elements are ordered in terms of decreasing local error, and the optimal fraction of elements to be refined is determined based on efficiency measures that take both error reduction and work into account. The goal is to reach a pre-specified bound on the global error with minimal amount of work. Two efficiency measures are discussed, ,work times error' and ,accuracy per computational cost'. The resulting refinement strategies are first compared for a one-dimensional (1D) model problem that may have a singularity. Modified versions of the efficiency strategies are proposed for the singular case, and the resulting adaptive methods are compared with a threshold-based refinement strategy. Next, the efficiency strategies are applied to the case of hp -refinement for the 1D model problem. The use of the efficiency-based refinement strategies is then explored for problems with spatial dimension greater than one. The ,work times error' strategy is inefficient when the spatial dimension, d, is larger than the finite element order, p, but the ,accuracy per computational cost' strategy provides an efficient refinement mechanism for any combination of d and p. Copyright © 2008 John Wiley & Sons, Ltd. [source] Dynamics of grazing lawn formation: an experimental test of the role of scale-dependent processesOIKOS, Issue 10 2008Joris P. G. M. Cromsigt Grazing lawns are characteristic for African savanna grasslands, standing out as intensely grazed patches of stoloniferous grazing-tolerant grass species. Grazing lawn development has been associated with grazing and increased nutrient input by large migratory herds. However, we argue that in systems without mass migrations disturbances, other than direct grazing, drive lawn development. Such disturbances, e.g. termite activity or megaherbivore middens, also increase nutrient input and keep the bunch vegetation down for a prolonged time period. However, field observations show that not all such disturbances lead to grazing lawns. We hypothesize that the initial disturbance has to be of a minimal threshold spatial scale, for grazing intensity to be high enough to induce lawn formation. We experimentally tested this idea in natural tall savanna grassland. We mowed different-sized plots to simulate initial disturbances of different scales (six times during one year) and applied fertilizer to half of the plots during two years to simulate increased nutrient input by herbivores or termite activity. Allowing grazing by naturally occurring herbivores, we followed the vegetation development over more than three years. Grazing kept bunch grass short in coarser, fertilized plots, while grasses grew out toward their initial height in fine-scale and unfertilized plots. Moreover, lawn grasses strongly increased in cover in plots with an increased nutrient input but only after coarser scale disturbance. These results support our hypothesis that an increased nutrient input in combination with grazing indeed induces grazing lawn formation, but only above a threshold scale of the initial disturbance. Our results provide an alternative mechanism for the development of grazing lawns in systems that lack mass migrating herds. Moreover, it gives a new spatial dimension to the processes behind grazing lawn development, and hence help to understand how herbivores might create and maintain spatial heterogeneity in grassland systems. [source] Spatial knowledge diffusion through collaborative networks,PAPERS IN REGIONAL SCIENCE, Issue 3 2007Corinne Autant-Bernard The theory of endogenous growth and the geography and growth synthesis both consider that local growth and spatial concentration of economic activities emanate from localised knowledge spillovers (Lucas 1988; Martin and Ottaviano 1999). Since the end of the 1980's, the spatial dimension of knowledge diffusion has been investigated from an empirical point of view, and the existence and role of local spillovers has been generally confirmed (see among others Jaffe 1989; Audretsch and Feldman 1996). The concern that now arises is to unravel the mechanisms underlying and explaining the geographical knowledge spillovers. The aim of this special issue is to present the latest new findings on such questions and to identify some new lines of research for future work. Before presenting the content of this special issue, we very briefly review the main results of the empirical literature on the geography of innovation. We also explain the context of this special issue by pointing out some of the limitations faced by this literature and, by stressing the complex dynamic and network dimensions of the observed processes of production and diffusion of knowledge. [source] Plattner's Arrow: Science and Multi-Dimensional TimeRATIO, Issue 3 2000Alasdair M. Richmond Might time be multi-dimensional? In exploring this question, this paper uses a thought-experiment about dimensionality, H. G. Wells' ,The Plattner Story'. Plattner has his left and right sides transposed after a trip through a fourth spatial dimension, a change with independent empirical consequences. This example is then generalised to reversals of the directions of time and entropy. Finally, this thought-experiment is related to relativistic theories of time and the possibility of preserving causality in a temporally multi-dimensional framework. [source] BERTRAND COMPETITION CAN YIELD HIGHER PRICES THAN MONOPOLYBULLETIN OF ECONOMIC RESEARCH, Issue 3 2007Helge Sanner D42; L11; R32 ABSTRACT If we take into account the spatial dimension of markets, prices of incumbent firms may be higher and consumer surplus may be lower with competition than with monopoly. This result obtains unambiguously, even in the supposedly highly competitive case of Bertrand competition. Moreover, we are able to show that consumers of the commodity may be worse off with duopoly, if the distance between the firms' sites is sufficiently large. [source] Meltwater discharge through the subglacial bed and its land-forming consequences from numerical experiments in the Polish lowland during the last glaciationEARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2009Jan A. Piotrowski Abstract Numerical experiments suggest that the last glaciation severely affected the upper lithosphere groundwater system in NW Poland: primarily its flow pattern, velocities and fluxes. We have simulated subglacial groundwater flow in two and three spatial dimensions using finite difference codes for steady-state and transient conditions. The results show how profoundly the ice sheet modifies groundwater pressure heads beneath and some distance beyond the ice margin. All model runs show water discharge at the ice forefield driven by ice-sheet-thickness-modulated, down-ice-decreasing hydraulic heads. In relation to non-glacial times, the transient 3D model shows significant changes in the groundwater flow directions in a regionally extensive aquifer ca. 90 m below the ice,bed interface and up to 40 km in front of the glacier. Comparison with empirical data suggests that, depending on the model run, only between 5 and 24% of the meltwater formed at the ice sole drained through the bed as groundwater. This is consistent with field observations documenting abundant occurrence of tunnel valleys, indicating that the remaining portion of basal meltwater was evacuated through a channelized subglacial drainage system. Groundwater flow simulation suggests that in areas of very low hydraulic conductivity and adverse subglacial slopes water ponding at the ice sole was likely. In these areas the relief shows distinct palaeo-ice lobes, indicating fast ice flow, possibly triggered by the undrained water at the ice,bed interface. Owing to the abundance of low-permeability strata in the bed, the simulated groundwater flow depth is less than ca. 200 m. Copyright © 2009 John Wiley & Sons, Ltd. [source] European Union Constitution-Making, Political Identity and Central European ReflectionsEUROPEAN LAW JOURNAL, Issue 2 2005It analyses both the temporal and spatial dimensions of constitution-making and addresses the problems of political identity related to ethnic divisions and civic demos. It starts by summarising the major arguments supporting the Union's constitution-making project and emphasises the Union's symbolic power as a polity built on the principles of civil society and parliamentary democracy. The EU's official rejection of ethnically based political identity played an important symbolic role in post-Communist constitutional and legal transformations in Central Europe in the 1990s. In the following part, the text analyses the temporal dimension of the EU's identity-building and constitution-making and emphasises its profoundly future-oriented structure. The concept of identity as the ,future in process' is the only option of how to deal with the absence of the European demos. Furthermore, it initiates the politically much-needed constitution-making process. The following spatial analysis of this process emphasises positive aspects of the horizontal model of constitution-making, its elements in the Convention's deliberation and their positive effect on the Central European accession states. The article concludes by understanding the emerging European identity as a multi-level identity of civil political virtues surrounded by old loyalties and traditions, which supports the conversational model of liberal democratic politics, reflects the continent's heterogeneity and leads to the beneficial combination of universal principles and political realism. [source] Controls of mantle plumes and lithospheric folding on modes of intraplate continental tectonics: differences and similaritiesGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2009Evgueni Burov SUMMARY Mantle plume activity and lithospheric folding by far-field stresses exerted from plate boundaries are two important end-members as mechanisms for continental intraplate deformation. The topographic expression of mantle plume impingement on continental lithosphere and lithospheric folding has some striking similarities. Observations from a number of areas in Europe's intraplate lithosphere demonstrate that these mechanisms commonly interact in space and time. We present the results of thermomechanical modelling addressing the role of factors such as the presence of a hot upper mantle, the spatial dimensions of the plume and the time constants involved in the temporal succession of plume activity and lithospheric folding by stress accumulation in intraplate continental lithosphere. The results demonstrate that both the processes, plume,lithosphere interactions and folding may interact resulting either in strong amplification, attenuation or modification of their surface expression. These inferences are compatible with a number of key observations on the nature and the temporal succession of topography evolution in the Alpine foreland, the Pannonian Basin, the Scandinavian continental margin and the Iberian Peninsula. [source] Post-seismic relaxation following the great 2004 Sumatra-Andaman earthquake on a compressible self-gravitating EarthGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2006Fred F. Pollitz SUMMARY The Mw, 9.0 2004 December 26 Sumatra-Andaman and Mw= 8.7 2005 March 28 Nias earthquakes, which collectively ruptured approximately 1800 km of the Andaman and Sunda subduction zones, are expected to be followed by vigorous viscoelastic relaxation involving both the upper and lower mantle. Because of these large spatial dimensions it is desirable to fully account for gravitational coupling effects in the relaxation process. We present a stable method of computing relaxation of a spherically-stratified, compressible and self-gravitating viscoelastic Earth following an impulsive moment release event. The solution is cast in terms of a spherical harmonic expansion of viscoelastic normal modes. For simple layered viscoelastic models, which include a low-viscosity oceanic asthenosphere, we predict substantial post-seismic effects over a region several 100s of km wide surrounding the eastern Indian Ocean. We compare observed GPS time-series from ten regional sites (mostly in Thailand and Indonesia), beginning in 2004 December, with synthetic time-series that include the coseismic and post-seismic effects of the 2004 December 26 and 2005 March 28 earthquakes. A viscosity structure involving a biviscous (Burgers body) rheology in the asthenosphere explains the pattern and amplitude of post-seismic offsets remarkably well. [source] Solution of the unsaturated soil moisture equation using repeated transformsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2001S. G. Fityus Abstract An alternative method of solution for the linearized ,theta-based' form of the Richards equation of unsaturated flow is developed in two spatial dimensions. The Laplace and Fourier transformations are employed to reduce the Richards equation to an ordinary differential equation in terms of a transformed moisture content and the transform variables, s and ,. Separate analytic solutions to the transformed equation are developed for initial states which are either in equilibrium or dis-equilibrium. The solutions are assembled into a finite layer formulation satisfying continuity of soil suction, thereby facilitating the analysis of horizontally stratified soil profiles. Solution techniques are outlined for various boundary conditions including prescribed constant moisture content, prescribed constant flux and flux as a function of moisture change. Example solutions are compared with linearized finite element solutions. The agreement is found to be good. An adaptation of the method for treating the quasilinearized Richards equation with variable diffusivity is also described. Comparisons of quasilinear solutions with some earlier semi-analytical, finite element and finite difference results are also favourable. Copyright © 2001 John Wiley & Sons, Ltd. [source] Numerical analysis of the rectangular domain decomposition methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 7 2009Younbae Jun Abstract When solving parabolic partial differential equations using finite difference non-overlapping domain decomposition methods, one often uses the stripwise decomposition of spatial domain and it can be extended to the rectangular decomposition without further analysis. In this paper, we analyze the rectangular decomposition when the modified implicit prediction (MIP) algorithm is used. We show that the performance of the rectangular decomposition and the stripwise decomposition is different. We compare spectral radius, maximum error, efficiency, and total operations of the rectangular and the stripwise decompositions. We investigate the accuracy of the interface of the rectangular decomposition and the effects of the correction phase of the rectangular decomposition. Numerical experiments have been done in both two and three spatial dimensions and show that the rectangular decomposition is not better than the stripwise decomposition. Copyright © 2008 John Wiley & Sons, Ltd. [source] Piecewise divergence-free discontinuous Galerkin methods for Stokes flowINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 5 2008Peter Hansbo Abstract In this paper, we consider different possibilities of using divergence-free discontinuous Galerkin methods for the Stokes problem in order to eliminate the pressure from the discrete problem. We focus on three different approaches: one based on a C0 approximation of the stream function in two dimensions (the vector potential in three dimensions), one based on the non-conforming Morley element (which corresponds to a divergence-free non-conforming Crouzeix,Raviart approximation of the velocities), and one fully discontinuous Galerkin method with a stabilization of the pressure that allows the edgewise elimination of the pressure variable before solving the discrete system. We limit the analysis in the stream function case to two spatial dimensions, while the analysis of the fully discontinuous approach is valid also in three dimensions. Copyright © 2006 John Wiley & Sons, Ltd. [source] Reduced-order modeling of parameterized PDEs using time,space-parameter principal component analysis,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 8 2009C. Audouze Abstract This paper presents a methodology for constructing low-order surrogate models of finite element/finite volume discrete solutions of parameterized steady-state partial differential equations. The construction of proper orthogonal decomposition modes in both physical space and parameter space allows us to represent high-dimensional discrete solutions using only a few coefficients. An incremental greedy approach is developed for efficiently tackling problems with high-dimensional parameter spaces. For numerical experiments and validation, several non-linear steady-state convection,diffusion,reaction problems are considered: first in one spatial dimension with two parameters, and then in two spatial dimensions with two and five parameters. In the two-dimensional spatial case with two parameters, it is shown that a 7 × 7 coefficient matrix is sufficient to accurately reproduce the expected solution, while in the five parameters problem, a 13 × 6 coefficient matrix is shown to reproduce the solution with sufficient accuracy. The proposed methodology is expected to find applications to parameter variation studies, uncertainty analysis, inverse problems and optimal design. Copyright © 2009 John Wiley & Sons, Ltd. [source] Accuracy of Galerkin finite elements for groundwater flow simulations in two and three-dimensional triangulationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2001Christian Cordes Abstract In standard finite element simulations of groundwater flow the correspondence between hydraulic head gradients and groundwater fluxes is represented by the stiffness matrix. In two-dimensional problems the use of linear triangular elements on Delaunay triangulations guarantees a stiffness matrix of type M. This implies that the local numerical fluxes are physically consistent with Darcy's law. This condition is fundamental to avoid the occurrence of local maxima or minima, and is of crucial importance when the calculated flow field is used in contaminant transport simulations or pathline evaluation. In three spatial dimensions, the linear Galerkin approach on tetrahedra does not lead to M -matrices even on Delaunay meshes. By interpretation of the Galerkin approach as a subdomain collocation scheme, we develop a new approach (OSC, orthogonal subdomain collocation) that is shown to produce M -matrices in three-dimensional Delaunay triangulations. In case of heterogeneous and anisotropic coefficients, extra mesh properties required for M -stiffness matrices will also be discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Generation of Arbitrary Lagrangian,Eulerian (ALE) velocities, based on monitor functions, for the solution of compressible fluid equationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10-11 2005B. V. Wells Abstract A moving mesh method is outlined based on the use of monitor functions. The method is developed from a weak conservation principle. From this principle a conservation law for the mesh position is derived. Using the Helmholtz decomposition theorem, this conservation law can be converted into an elliptic equation for a mesh velocity potential. The moving mesh method is discretized using standard finite elements. Once the mesh velocities are obtained an arbitrary Lagrangian,Eulerian (ALE) (Journal of Computational Physics 1974; 14:227) fluid solver is used to update the solution on the adaptive mesh. Results are shown for the compressible Euler equations of gas dynamics in one and two spatial dimensions. Two monitor functions are used, the fluid density (which corresponds to a Lagrangian description), and a function which includes the density gradient. A variety of test problems are considered. Copyright © 2005 John Wiley & Sons, Ltd. [source] On the design of bandwidth efficient signalling for indoor wireless optical channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2005Steve HranilovicArticle first published online: 15 MAR 200 Abstract It is well known that indoor wireless optical channels are limited not only in transmitted optical power, but also in signalling bandwidth. This bandwidth constraint arises due to multipath dispersion in indoor settings as well as due to response time limitations of optoelectronic components. This paper presents an overview of theoretical and practical issues in the design of signalling for bandwidth constrained intensity modulated, direct detection wireless optical channels. A brief overview of the salient qualities of the wireless optical channel are presented to highlight the amplitude constraints which arise. A survey of modulation design is then presented which includes the review of a general technique to represent optical intensity modulation in a signal space and to construct optical intensity lattice codes. Results on the channel capacity of indoor wireless optical channels are surveyed and particular emphasis is placed on recently derived asymptotically exact bounds. The use of multiple emitters and receivers in wireless optical channels is also presented and particular emphasis is placed on techniques which exploit spatial dimensions to improve spectral performance. The paper concludes with some remarks regarding the status of the research area and suggestions for future work. Copyright © 2005 John Wiley & Sons, Ltd. [source] Spatial distribution of spawning sites of pikeperch [Sander lucioperca (L.)] in a highly eutrophic clay-turbid lake , implications for managementJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2006H. Lehtonen Summary The spawning sites of pikeperch were mapped using artificial spawning nests in the clay-turbid Lake Tuusulanjärvi in southern Finland to protect the most important spawning areas. Altogether 272 artificial spawning nests were set before actual spawning on potential spawning grounds. The first observations of eggs were made on 26 May at a surface water temperature of 12°C. No new eggs were found after 10 June at water temperature of 16°C. The nests were removed on 18 June when the larvae had already hatched. The study demonstrated that artificial spawning nests could be used to evaluate both duration and spatial dimensions of spawning of pikeperch. [source] Two-dimensional metamaterial opticsLASER PHYSICS LETTERS, Issue 4 2010I.I. Smolyaninov Abstract While three-dimensional photonic metamaterials are difficult to fabricate, many new concepts and ideas in the metamaterial optics can be realized in two spatial dimensions using planar optics of surface plasmon polaritons. In this paper we review recent progress in this direction. Two-dimensional photonic crystals, hyperbolic metamaterials, and plasmonic focusing devices are demonstrated and used in novel microscopy and waveguiding schemes. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Beethoven's Birdstrokes: Figuration, Subjectivity, and the Force of the Score in the Pastoral Symphony and Copying BeethovenLITERATURE COMPASS (ELECTRONIC), Issue 8 2010William Kumbier The inscription of a musical score is, at root, a figural gesture. As the score's figures construct a metaphoric bridge, from the composer's conception through their spatial representation to the composition's aural realization, they also play, reflexively, off and into other musical figurations and what those figurations signify. Beethoven's Pastoral Symphony, Op. 68, provides a rich and distinctive instance of scoring in which the musical figurations seem especially charged to generate meanings beyond the sounds that one ,hears' when reading the score mainly as a script for performance. This work, despite Beethoven's famous assertion that it is ,more expression of feeling than painting', mediates aural and visual realms with its deft deployment of musical figurations traditionally heard and seen as pictorial, notably through those figurations associated with water and birdsong in the work's second movement, ,Scene by the Brook'. In Beethoven's scoring his unusual insistence on the physical and pictorial, his development of the spatial dimensions of the music, intensifies the music's programmatic or mimetic thrust but also marks the music's metamimetic distance from its pastoral referents. Beethoven's figuration thus becomes a means of mediating subjective consciousness and the world that consciousness encounters or imagines. The force of musical figuration and its implications for subjectivity, again with key reference to Beethoven, are vividly realized also in the recent cinematic reading of the scoring and performance of Beethoven's Ninth Symphony, Agnieszka Holland's Copying Beethoven (2007). [source] A fourth-order compact algorithm for nonlinear reaction-diffusion equations with Neumann boundary conditionsNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 3 2006Wenyuan Liao Abstract In this article, we discuss a scheme for dealing with Neumann and mixed boundary conditions using a compact stencil. The resulting compact algorithm for solving systems of nonlinear reaction-diffusion equations is fourth-order accurate in both the temporal and spatial dimensions. We also prove that the standard second-order approximation to zero Neumann boundary conditions provides fourth-order accuracy when the nonlinear reaction term is independent of the spatial variables. Numerical examples, including an application of this algorithm to a mathematical model describing frontal polymerization process, are presented in the article to demonstrate the accuracy and efficiency of the scheme. © 2005 Wiley Periodicals, Inc. 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