Distribution by Scientific Domains
Distribution within Physics and Astronomy

Kinds of Physics

  • basic physics
  • computational physics
  • condensed matter physics
  • device physics
  • flow physics
  • fundamental physics
  • matter physics
  • modern physics
  • particle physics
  • quantum physics
  • semiconductor physics
  • solar physics
  • solid state physics
  • state physics
  • statistical physics
  • theoretical physics

  • Selected Abstracts


    THE HEYTHROP JOURNAL, Issue 4 2008
    First page of article [source]

    Introductory quantum physics courses using a LabVIEW multimedia module

    Ismael Orquín
    Abstract We present the development of a LabVIEW multimedia module for introductory Quantum Physics courses and our experience in the use of this application as an educational tool in learning methodologies. The program solves the time-dependent Schrödinger equation (TDSE) for arbitrary potentials. We describe the numerical method used for solving this equation, as well as some mathematical tools employed to reduce the calculation time and to obtain more accurate results. As an illustration, we present the evolution of a wave packet for three different potentials: the repulsive barrier potential, the repulsive step potential, and the harmonic oscillator. This application has been successfully integrated in the learning strategies of the course Quantum Physics for Engineering at the Polytechnic University of Valencia, Spain. © 2007 Wiley Periodicals, Inc. Comput Appl Eng Educ. 15: 124,133, 2007; Published online in Wiley InterScience (; DOI 10.1002/cae.20100 [source]

    Artificial Animals and Humans: From Physics to Intelligence

    Demetri Terzopoulos
    The confluence of virtual reality and artificial life, an emerging discipline that spans the computational and biological sciences, has yielded synthetic worlds inhabited by realistic, artificial flora and fauna. Artificial animals are complex synthetic organisms that possess functional biomechanical bodies, sensors, and brains with locomotion, perception, behavior, learning, and cognition centers. Artificial humans and other animals are of interest in computer graphics because they are self-animating characters that dramatically advance the state of the art of production animation and interactive game technologies. More broadly, these biomimetic autonomous agents in their realistic virtual worlds also foster deeper, computationally oriented insights into natural living systems. [source]

    Contextual constraint modeling in Grid application workflows

    Greg Graham
    Abstract This paper introduces a new mechanism for specifying constraints in distributed workflows. By introducing constraints in a contextual form, it is shown how different people and groups within collaborative communities can cooperatively constrain workflows. A comparison with existing state-of-the-art workflow systems is made. These ideas are explored in practice with an illustrative example from High-Energy Physics. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Physics, Chemistry and Applications of the AC Diaphragm Discharge and Related Discharges in Electrolyte Solutions

    A. I. Maximov
    Abstract Three types of the underwater discharges produced by means of AC voltage sources (500-2000 V, 0.05-1 A) were investigated. Dynamic volt-ampere characteristics and radiation intensity of these discharges were measured. It was observed the optical afterglow time up to 0.1-0.2 s. The information about their chemical action was got by stimulation of the oxidation of the organic and inorganic substances. It was found that the treatment of the cellulose and the flax by means of the underwater discharges results in the change of their molecular mass, lignin contain and surface concentration of the oxygen containing functional groups. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Plasma Edge Physics with B2-Eirene

    R. Schneider
    Abstract The B2-Eirene code package was developed to give better insight into the physics in the scrape-off layer (SOL), which is defined as the region of open field-lines intersecting walls. The SOL is characterised by the competition of parallel and perpendicular transport defining by this a 2D system. The description of the plasma-wall interaction due to the existence of walls and atomic processes are necessary ingredients for an understanding of the scrape-off layer. This paper concentrates on understanding the basic physics by combining the results of the code with experiments and analytical models or estimates. This work will mainly focus on divertor tokamaks, but most of the arguments and principles can be easily adapted also to other concepts like island divertors in stellarators or limiter devices. The paper presents the basic equations for the plasma transport and the basic models for the neutral transport. This defines the basic ingredients for the SOLPS (Scrape-Off Layer Plasma Simulator) code package. A first level of understanding is approached for pure hydrogenic plasmas based both on simple models and simulations with B2-Eirene neglecting drifts and currents. The influence of neutral transport on the different operation regimes is here the main topic. This will finish with time-dependent phenomena for the pure plasma, so-called Edge Localised Modes (ELMs). Then, the influence of impurities on the SOL plasma is discussed. For the understanding of impurity physics in the SOL one needs a rather complex combination of different aspects. The impurity production process has to be understood, then the effects of impurities in terms of radiation losses have to be included and finally impurity transport is necessary. This will be introduced with rising complexity starting with simple estimates, analysing then the detailed parallel force balance and the flow pattern of impurities. Using this, impurity compression and radiation instabilities will be studied. This part ends, combining all the elements introduced before, with specific, detailed results from different machines. Then, the effect of drifts and currents is introduced and their consequences presented. Finally, some work on deriving scaling laws for the anomalous turbulent transport based on automatic edge transport code fitting procedures will be described. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Sheath Physics and Boundary Conditions for Edge Plasmas

    R. H. Cohen
    Abstract The boundary conditions of mass, momentum, energy, and charge appropriate for fluid formulations of edge plasmas are surveyed. We re-visit the classic problem of 1-dimensional flow, and note that the "Bohm sheath criterion" is requirement of connectivity of the interior plasma with the external world, not the result of termination of the plasma by a wall. We show that the nature of the interior plasma solution is intrinsically different for ion sources that inject above and below the electron sound speed. We survey the appropriate conditions to apply, and resultant fluxes, for a magnetic field obliquely incident on a wall, including the presence of drifts and radial transport. We discuss the consequences of toroidal asymmetries in wall properties, as well as experimental tests of such effects. Finally, we discuss boundary-condition modifications in the case of rapidly varying plasma conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Reconstructing Macroeconomics: A Perspective from Statistical Physics and Combinational Stochastic Processes.

    ECONOMICA, Issue 301 2009
    No abstract is available for this article. [source]

    Modeling the Porosity Formation in Austenitic SGI Castings by Using a Physics-Based Material Model,

    B. Pustal
    Abstract On solidification, microsegregations build up in solid phases due to changes in solid concentrations with temperature. Diffusion, which is a kinetic process, usually reduces the occurrence of microsegregations. This work is aimed at modeling such kinetic effects on the solidification of austenitic cast iron, using a holistic approach. For this purpose, a microsegregation model is developed and validated. Moreover, this model is directly coupled to a commercial process-simulation tool and thermodynamic software. A series of GJSA-XNiCr 20-2 clamp-rings is cast by varying the inoculation state and the number of feeders. The composition of this cast alloy is analyzed and the microstructure characterized to provide input data for the microsegregation model. In order to validate the software, cooling curves are recorded; differential thermal analysis, electron dispersive X-ray analysis and electron probe micro analysis are carried out. Furthermore, the porosity within the casting is analyzed by X-ray. By performing coupled simulations, the different cooling characteristics within the casting lead to pronounced differences in phase fractions and solidification temperatures which are due to dendrite arm coarsening. The hot spot effect below the feeders is assisted by a shift towards lower solidification temperatures over the solidification time. This shift is a result of the local cooling characteristics, which can only be predicted when process simulation is directly coupled with material simulation. The porosity predictions and the porosity analysis exhibit good agreement. A comparison between experimental and virtual cooling curves closes, implying that the novel coupling concept and its implementation are valid. [source]

    Lal, R. & Shukla, M.K. Principles of Soil Physics.

    2004. x + 716 pp., Marcel Dekker, New York
    No abstract is available for this article. [source]

    Pachepsky, Y., Radcliff, D.E. & Selim, H.M. (eds) Scaling Methods in Soil Physics.

    2003. xviii + 434 pp., Boca Raton, CRC Press
    No abstract is available for this article. [source]

    Brane tilings and their applications

    M. Yamazaki
    Abstract We review recent developments in the theory of brane tilings and four-dimensional ,, = 1 supersymmetric quiver gauge theories. This review consists of two parts. In part I, we describe foundations of brane tilings, emphasizing the physical interpretation of brane tilings as fivebrane systems. In part II, we discuss application of brane tilings to AdS/CFT correspondence and homological mirror symmetry. More topics, such as orientifold of brane tilings, phenomenological model building, similarities with BPS solitons in supersymmetric gauge theories, are also briefly discussed. This paper is a revised version of the author's master's thesis submitted to Department of Physics, Faculty of Science, the University of Tokyo on January 2008, and is based on his several papers and some works in progress [1,7]. [source]

    Fortschritte der Physik in theWorld Year of Physics

    D. Lüst
    No abstract is available for this article. [source]

    Physics-based GPS data inversion to estimate three-dimensional elastic and inelastic strain fields

    Akemi Noda
    SUMMARY The Earth's crust is macroscopically treated as a linear elastic body, but it includes a number of defects. The occurrence of inelastic deformation such as brittle fracture at the defects brings about elastic deformation in the surrounding regions. The crustal deformation observed through geodetic measurements is the sum of the inelastic deformation as source and the elastic deformation as effect. On such a basic idea, we created a theory of physics-based strain analysis with general source representation by moment tensor, and developed an inversion method to separately estimate 3-D elastic and inelastic strain fields from GPS data. In this method, first, the optimum distribution of moment density tensor is determined from observed GPS data by using Akaike's information criterion. Then, the elastic and inelastic strain fields are obtained from the optimum moment tensor distribution by theoretical computation and direct conversion with elastic compliance tensor, respectively. We applied the inversion method to GPS horizontal velocity data, and succeeded in separately estimating 3-D elastic and inelastic strain rate fields in the Niigata,Kobe transformation zone, central Japan. As for the surface patterns of total strain, the present results of 3-D physics-based inversion analysis accord with the previous results of 2-D geometric inversion analysis. From the 3-D patterns of the inverted elastic and inelastic strain fields, we revealed that the remarkable horizontal contraction in the Niigata,Kobe transformation zone is elastic and restricted near the surface, but the remarkable shear deformation is inelastic and extends over the upper crust. [source]

    Charge Transport Physics of Conjugated Polymer Field-Effect Transistors

    ADVANCED MATERIALS, Issue 34 2010
    Henning Sirringhaus
    Abstract Field-effect transistors based on conjugated polymers are being developed for large-area electronic applications on flexible substrates, but they also provide a very useful tool to probe the charge transport physics of these complex materials. In this review we discuss recent progress in polymer semiconductor materials, which have brought the performance and mobility of polymer devices to levels comparable to that of small-molecule organic semiconductors. These new materials have also enabled deeper insight into the charge transport physics of high-mobility polymer semiconductors gained from experiments with high charge carrier concentration and better molecular-scale understanding of the electronic structure at the semiconductor/dielectric interface. [source]

    Institute of Physics, CAS: (Adv. Mater.

    ADVANCED MATERIALS, Issue 45 2009
    Founded in 1928, the Institute of Physics of the Chinese Academy of Sciences has become one of China's leading research institutions. In 2003, the Institute acquired the Beijing National Laboratory for Condensed Matter Physics, one of the first six national laboratories in China. Its current programs focus on condensed matter physics and its theory, optical physics, atomic and molecular physics, soft matter, plasma physics, and computational physics. [source]

    Materials Science at the Institute of Physics, Chinese Academy of Sciences

    ADVANCED MATERIALS, Issue 45 2009
    Yupeng Wang
    No abstract is available for this article. [source]

    Rapid simulated hydrologic response within the variably saturated near surface

    Brian A. Ebel
    Abstract Column and field experiments have shown that the hydrologic response to increases in rainfall rates can be more rapid than expected from simple estimates. Physics-based hydrologic response simulation, with the Integrated Hydrology Model (InHM), is used here to investigate rapid hydrologic response, within the variably saturated near surface, to temporal variations in applied flux at the surface boundary. The factors controlling the speed of wetting front propagation are discussed within the Darcy,Buckingham conceptual framework, including kinematic wave approximations. The Coos Bay boundary-value problem is employed to examine simulated discharge, pressure head, and saturation responses to a large increase in applied surface flux. The results presented here suggest that physics-based simulations are capable of representing rapid hydrologic response within the variably saturated near surface. The new InHM simulations indicate that the temporal discretization and measurement precision needed to capture the rapid subsurface response to a spike increase in surface flux, necessary for both data-based analyses and evaluation of physics-based models, are smaller than the capabilities of the instrumentation deployed at the Coos Bay experimental catchment. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Physics-based hydrologic-response simulation: Seeing through the fog of equifinality

    Brian A. Ebel
    First page of article [source]

    Dr Olivier Coussy, Scientist and Engineer of the Mechanics and Physics of Porous Materials (1953,2010)

    Franz-Josef Ulm
    No abstract is available for this article. [source]

    Conserving Galerkin weak formulations for computational fracture mechanics

    Shaofan Li
    Abstract In this paper, a notion of invariant Galerkin-variational weak forms is proposed. Two specific invariant variational weak forms, the J-invariant and the L-invariant, are constructed based on the corresponding conservation laws in elasticity, one of which is the conservation of Eshelby's energy-momentum (Eshelby. Philos. Trans. Roy. Soc. 1951; 87: 12; In Solid State Physics, Setitz F, Turnbull D (eds). Academic Press: New York, 1956; 331; Rice, J. Appl. Mech. 1968; 35: 379). It is shown that the finite element solution obtained from the invariant Galerkin weak formulations proposed here can conserve the value of J-integral, or L-integral exactly. In other words, the J and L integrals of the Galerkin finite element solutions are path independent in the discrete sense. It is argued that by using the J-invariant Galerkin weak form to compute near crack-tip field in an elastic solid, one may accurately calculate the crack extension energy release rate and subsequently the stress intensity factors in numerical computations, because the flux of the energy-momentum is conserved in discrete computations. This may provide an alternative means to accurately simulate crack growth and propagation. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Comparison of three second-order accurate reconstruction schemes for 2D Euler and Navier,Stokes compressible flows on unstructured grids

    N. P. C. Marques
    Abstract This paper reports an intercomparison of three second-order accurate reconstruction schemes to predict 2D steady-state compressible Euler and Navier,Stokes flows on unstructured meshes. The schemes comprise one monotone slope limiter (Barth and Jespersen, A1AA Paper 89-0366, 1989) and two approximately monotone methods: the slope limiter due to Venkatakrishnan and a data-dependent weighting least-squares procedure (Gooch, Journal of Computational Physics, 1997; 133:6,17). In addition to the 1D scalar wave problem, comparisons were performed under two inviscid test cases: a supersonic 10° ramp and a supersonic bump; and two viscous laminar compressible flow cases: the Blasius boundary layer and a double-throated nozzle. The data-dependent oscillatory behaviour is found to be dependent on a user-supplied constant. The three schemes are compared in terms of accuracy and computational efficiency. The results show that the data-dependent procedure always returns a numerical steady-state solution, more accurate than the ones returned by the slope limiters. Its use for Navier,Stokes flow calculations is recommended. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Physics-based preconditioner for iterative algorithms in multi-scatterer and multi-boundary method of moments formulations

    Jürgen v. Hagen
    Abstract An efficient method to solve electromagnetic scattering problems involving several metallic scatterers or bodies composed of dielectric and metallic regions is proposed. So far, the method of moments has successfully been applied to large arrays of identical scatterers when it was combined with preconditioned iterative algorithms to solve for the linear system of equations. Here, the method is generalized to geometries that are composed of several metallic elements of different shapes and sizes, and also to scatterers that are composed of metallic and dielectric regions. The method uses in its core an iterative algorithm, preferably the transpose-free quasi-minimum residual (TFQMR) algorithm, and a block diagonal Jacobi preconditioner. For best performance, the blocks for the preconditioner are chosen according to individual scatterers or groups of scatterers for the array case, and according to the electric and magnetic current basis functions for dielectric/metallic scatterers. The iterative procedure converges quickly for an optimally chosen preconditioner, and is robust even for a non-optimal preconditioner. Reported run times are compared to run times of an efficiently programmed LU factorization, and are shown to be significantly lower. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    A further work on multi-phase two-fluid approach for compressible multi-phase flows

    Yang-Yao Niu
    Abstract This paper is to continue our previous work Niu (Int. J. Numer. Meth. Fluids 2001; 36:351,371) on solving a two-fluid model for compressible liquid,gas flows using the AUSMDV scheme. We first propose a pressure,velocity-based diffusion term originally derived from AUSMDV scheme Wada and Liou (SIAM J. Sci. Comput. 1997; 18(3):633,657) to enhance its robustness. The scheme can be applied to gas and liquid fluids universally. We then employ the stratified flow model Chang and Liou (J. Comput. Physics 2007; 225:240,873) for spatial discretization. By defining the fluids in different regions and introducing inter-phasic force on cell boundary, the stratified flow model allows the conservation laws to be applied on each phase, and therefore, it is able to capture fluid discontinuities, such as the fluid interfaces and shock waves, accurately. Several benchmark tests are studied, including the Ransom's Faucet problem, 1D air,water shock tube problems, 2D shock-water column and 2D shock-bubble interaction problems. The results indicate that the incorporation of the new dissipation into AUSM+ -up scheme and the stratified flow model is simple, accurate and robust enough for the compressible multi-phase flows. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Generation of Arbitrary Lagrangian,Eulerian (ALE) velocities, based on monitor functions, for the solution of compressible fluid equations

    B. 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]

    Absorbing boundary condition on elliptic boundary for finite element analysis of water wave diffraction by large elongated bodies

    Subrata Kumar Bhattacharyya
    Abstract In a domain method of solution of exterior scalar wave equation, the radiation condition needs to be imposed on a truncation boundary of the modelling domain. The Bayliss, Gunzberger and Turkel (BGT) boundary dampers of first- and second-orders, which require a circular cylindrical truncation boundary in the diffraction-radiation problem of water waves, have been particularly successful in this task. However, for an elongated body, an elliptic cylindrical truncation boundary has the potential to reduce the modelling domain and hence the computational effort. Grote and Keller [On non-reflecting boundary conditions. Journal of Computational Physics 1995; 122: 231,243] proposed extension of the first- and second-order BGT dampers for the elliptic radiation boundary and used these conditions to the acoustic scattering by an elliptic scatterer using the finite difference method. In this paper, these conditions are implemented for the problem of diffraction of water waves using the finite element method. Also, it is shown that the proposed extension works well only for head-on wave incidence. To remedy this, two new elliptic dampers are proposed, one for beam-on incidence and the other for general wave incidence. The performance of all the three dampers is studied using a numerical example of diffraction by an elliptic cylinder. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    On circuit models for quantum-classical networks,

    Árpád I. Csurgay
    Abstract Physics is not scale invariant, and today the scale of atoms and molecules challenges designers of machines in which quantum effects have dominant sway. What role could circuit theory play in designing machines described by quantum-classical models? Classical equivalent circuits do exist for systems composed of metal contacted and wired devices, such as resonant tunneling diodes, single electron transistors, metal,insulator,metal diodes, etc. circuits, but not for quantum-entangled networks, such as multi-quantum-state atoms. If devices were not contacted and wired by macroscopic metals, i.e. devices were classically field coupled, then generalized circuit models can be introduced. Case studies have been presented on the role of circuit models in quantum-classical systems. However, there are no ideal circuit elements capable of capturing the port properties of quantum-mechanical and/or quantum-optical subsystems and their coupling to classical waveguides or cavities. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Simulation of the intraseasonal and the interannual variability of rainfall over West Africa with RegCM3 during the monsoon period

    M. B. Sylla
    Abstract Intraseasonal and interannual variability of rainfall is simulated using the International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3) over West Africa. The intraseasonal variability of rainfall showing three distinct phases and the monsoon jump is well reproduced in the simulation. In addition, the regional model shows that while the monsoon rainbelt moves to the Sahel, the African Easterly Jet (AEJ) undergoes a northward migration and a weakening from June to August, when the core is at its northernmost location. This coexists with the appearance and the strengthening of the Tropical Easterly Jet (TEJ), the development and increased activity of the African Easterly Waves (AEWs), and the intensification and northward shift of the ascent between the AEJ and the TEJ core levels and axis. Similarly, the simulated interannual variability of rainfall over West Africa, the Guinea region, and the Sahel, as well as the variability of atmospheric features during contrasting wet and dry years, is also well captured. In fact, in the simulation during dry years the AEWs activity is decreased while the AEJ is strengthened and migrates southward, the TEJ becomes weaker, and the ascent between the levels of the AEJ and the TEJ decreases. The simulated rainfall variability and the behavior of the related features during the rainy season and during contrasting wet and dry years are in line with previous studies that used observations and reanalysis. We conclude that this model performance is of sufficient quality for application to the study of climate processes and mechanisms over West Africa. Copyright © 2009 Royal Meteorological Society [source]

    Organizational emergence in networked collaboration

    Ari-Pekka Hameri
    Abstract Research on complex adaptive systems has generated several conceptual parables to explain systems with emergent behaviour. One prominent use for terms such as self-organization, evolutionary trajectories, co-evolution and punctuated equilibrium has been in understanding human organizations. In such systems, emergent behaviour is demonstrated in novel structures, processes and spin-offs that cannot be explained just by studying single components of the organization and the intelligence embedded in them. Instead of solely exploiting the qualitative explanatory power of the evolutionary concepts, this paper focuses also on quantitative methods to track emergent behaviour in a globally distributed, constantly fluctuating and highly networked project organization. The underlying case is that of CERN (CERN, the European Laboratory for Particle Physics, has its headquarters in Geneva. At present, its Member States are Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, the Slovak Republic, Spain, Sweden, Switzerland and the United Kingdom. Israel, the Russian Federation, Turkey, Yugoslavia (status suspended after the UN embargo, June 1992), the European Commission and UNESCO have observer status.) and its decade long accelerator project, which strongly relies on electronic communication and networking to achieve its major objectives due to be accomplished by the year 2006. By using time series and self-organizing maps to analyse the global interaction among project groups and individuals the paper provides new insight to the understanding of emergent behaviour in human organizations. The key result of the study concerns the rigid deep structure of each case organization that seems to remain intact for the duration of the whole project. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Heat transfer during microwave combination heating: Computational modeling and MRI experiments

    AICHE JOURNAL, Issue 9 2010
    Vineet Rakesh
    Abstract Combination of heating modes such as microwaves, convection, and radiant heating can be used to realistically achieve the quality and safety needed for cooking processes and, at the same time, make the processes faster. Physics-based computational modeling used in conjunction with MRI experimentation can be used to obtain critical understanding of combination heating. The objectives were to: (1) formulate a fully coupled electromagnetics - heat transfer model, (2) use magnetic resonance imaging (MRI) experiments to determine the 3D spatial and temporal variation of temperatures and validate the numerical model, (3) use the insight gained from the model and experiments to understand the combination heating process and to optimize it. The different factors that affect heating patterns during combination heating such as the type of heating modes used, placement of sample, and microwave cycling were considered. Objective functions were defined and minimized for design and optimization. The use of such techniques can lead to greater control and automation of combination heating process benefitting the food process and product developers immensely. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source]