Meso-scale machining capabilities and issues
Energy Technology Data Exchange (ETDEWEB)
BENAVIDES,GILBERT L.; ADAMS,DAVID P.; YANG,PIN
2000-05-15
Meso-scale manufacturing processes are bridging the gap between silicon-based MEMS processes and conventional miniature machining. These processes can fabricate two and three-dimensional parts having micron size features in traditional materials such as stainless steels, rare earth magnets, ceramics, and glass. Meso-scale processes that are currently available include, focused ion beam sputtering, micro-milling, micro-turning, excimer laser ablation, femto-second laser ablation, and micro electro discharge machining. These meso-scale processes employ subtractive machining technologies (i.e., material removal), unlike LIGA, which is an additive meso-scale process. Meso-scale processes have different material capabilities and machining performance specifications. Machining performance specifications of interest include minimum feature size, feature tolerance, feature location accuracy, surface finish, and material removal rate. Sandia National Laboratories is developing meso-scale electro-mechanical components, which require meso-scale parts that move relative to one another. The meso-scale parts fabricated by subtractive meso-scale manufacturing processes have unique tribology issues because of the variety of materials and the surface conditions produced by the different meso-scale manufacturing processes.
Meso-scale turbulence in living fluids
Dunkel, Jorn; Wensink, Rik; Heidenreich, Sebastian; Drescher, Knut; Goldstein, Ray; Loewen, Hartmut; Yeomans, Julia
2012-11-01
The mathematical characterization of turbulence phenomena in active non-equilibrium fluids proves even more difficult than for conventional liquids or gases. It is not known which features of turbulent phases in living matter are universal or system-specific, or which generalizations of the Navier-Stokes equations are able to describe them adequately. We combine experiments, particle simulations, and continuum theory to identify the statistical properties of self-sustained meso-scale turbulence in active systems. To study how dimensionality and boundary conditions affect collective bacterial dynamics, we measured energy spectra and structure functions in dense Bacillus subtilis suspensions in quasi-2D and 3D geometries. Our experimental results for the bacterial flow statistics agree well with predictions from a minimal model for self-propelled rods, suggesting that at high concentrations the collective motion of the bacteria is dominated by short-range interactions. To provide a basis for future theoretical studies, we propose a minimal continuum model for incompressible bacterial flow. A detailed numerical analysis of the 2D case shows that this theory can reproduce many of the experimentally observed features of self-sustained active turbulence. Supported by the ERC, EPSRC and DFG.
Zhang, Jie
2014-01-01
Based on the plenty method, this paper describes a numerical method for 2D non-smooth contact problems with Coulomb friction and bilateral constraints and its application to the simulation of statics and dynamics for a frictional translational joint. Comparison is made with results obtained using a finite element program, ANSYS.
One particle properties in the 2D Coulomb problem. Luttinger-Ward variational approach
Energy Technology Data Exchange (ETDEWEB)
Agnihotri, M.P.
2007-04-27
In this work, we have studied the 2D Coulomb problem. We used the Luttinger-Ward variational principle to determine the self-energy {sigma} in ring approximation. The use of an ansatz for {sigma} enables us to perform the frequency sums (integrals as T {yields} 0) analytically. Compared to the usual procedure of iterating the self consistency equation with free Green's function as starting points, the present approach is superior. It works for higher density parameter r{sub s} (low density) where the iteration already fails to converge. The motivation of the present work is the quantum Hall system at filling factor 1/2. The Luttinger-Ward procedure is a rather powerful method in particular if combined with an analytical ansatz for {sigma}. The computation performed here for 2DEG has to be seen as a first step: There, the experiment shows the features of a free Fermion system that is interpreted as a system of Composite Fermions. If one studies the self energy of the Composite Fermions in an conserved approximation that corresponds to the ring approximation, one encounters a self consistency equation. However, an iterative solution of this equation meets with a complication: Instead of the polarization part {pi}{sub 00}, in the case of the Composite Fermion there appears the longitudinal polarization part {pi}{sub LL} that has an additional factor (2k + q){sup 2} under the k integral. This integral converges only after the frequency integral is performed. It is highly difficult to reproduce this numerically. Here, the Luttinger-Ward variational approach applied to the 2D Coulomb problem in the present work looks promising. For the 2D Coulomb problem, in the ring approximation for the LW thermodynamic potential, that already leads to a formidable integral equation that has to be studied numerically. (orig.)
Meso-scale wind variability. Final report
Energy Technology Data Exchange (ETDEWEB)
Larsen, S.; Larsen, X.; Vincent, C.; Soerensen, P.; Pinson, P.; Trombe, P.-J.; Madsen, H.; Cutululis, N.
2011-11-15
The project has aimed to characterize mesoscale meteorological phenomenon for the North Sea and the Inner Danish waters, and additionally aimed on improving the predictability and quality of the power production from offshore windfarms. The meso-scale meteorology has been characterized with respect to the physical processes, climatology, spectral characteristics and correlation properties based on measurements from wind farms, satellite data (SAR) and mesoscale numerical modeling (WRF). The abilities of the WRF model to characterize and predict relevant mesoscale phenomenon has been proven. Additionally application of statistical forecasting, using a Markov switching approach that can be related to the meteorological conditions, to analyze and short term predict the power production from an offshore wind farms have been documented. Two PhD studies have been conducted in connection with the project. The project has been a cooperative project between Risoe DTU, IMM DTU, DONG Energy, Vattenfall and VESTAS. It is registered as Energinet.dk, project no. 2007-1-7141. (Author)
Deformation Crossover: from nano to meso scale
Energy Technology Data Exchange (ETDEWEB)
Cheng, Sheng [ORNL; Stoica, Alexandru Dan [ORNL; Wang, Xun-Li [ORNL; Liu, Chain T [ORNL; Horton Jr, Joe A [ORNL; Brown, Donald [Los Alamos National Laboratory (LANL); Clausen, B [Los Alamos National Laboratory (LANL); Liaw, Peter K [University of Tennessee, Knoxville (UTK)
2009-01-01
By investigating intergranular strains using in-situ high-energy x-ray and neutron diffraction, we demonstrate significantly different deformation behavior from previously observed in nanocrystalline and ultrafine-grained Ni. Little intergranular strain or texture change was found in nanocrystalline Ni indicating a grain boundary mediated deformation mechanism. A remarkable intergranular strain build-up was observed in ultrafine-grained Ni, which was attributed to dislocation activities, but the unusual angular dependence of intergranular strains gave evidence of stress relaxation by deformation twinning, as confirmed by TEM observations. From the intergranular strain evolution and the texture change, clear evidence of deformation crossovers is presented in Ni with grain sizes from nano to meso scale.
Probabilistic, meso-scale flood loss modelling
Kreibich, Heidi; Botto, Anna; Schröter, Kai; Merz, Bruno
2016-04-01
Flood risk analyses are an important basis for decisions on flood risk management and adaptation. However, such analyses are associated with significant uncertainty, even more if changes in risk due to global change are expected. Although uncertainty analysis and probabilistic approaches have received increased attention during the last years, they are still not standard practice for flood risk assessments and even more for flood loss modelling. State of the art in flood loss modelling is still the use of simple, deterministic approaches like stage-damage functions. Novel probabilistic, multi-variate flood loss models have been developed and validated on the micro-scale using a data-mining approach, namely bagging decision trees (Merz et al. 2013). In this presentation we demonstrate and evaluate the upscaling of the approach to the meso-scale, namely on the basis of land-use units. The model is applied in 19 municipalities which were affected during the 2002 flood by the River Mulde in Saxony, Germany (Botto et al. submitted). The application of bagging decision tree based loss models provide a probability distribution of estimated loss per municipality. Validation is undertaken on the one hand via a comparison with eight deterministic loss models including stage-damage functions as well as multi-variate models. On the other hand the results are compared with official loss data provided by the Saxon Relief Bank (SAB). The results show, that uncertainties of loss estimation remain high. Thus, the significant advantage of this probabilistic flood loss estimation approach is that it inherently provides quantitative information about the uncertainty of the prediction. References: Merz, B.; Kreibich, H.; Lall, U. (2013): Multi-variate flood damage assessment: a tree-based data-mining approach. NHESS, 13(1), 53-64. Botto A, Kreibich H, Merz B, Schröter K (submitted) Probabilistic, multi-variable flood loss modelling on the meso-scale with BT-FLEMO. Risk Analysis.
Onset of meso-scale turbulence in active nematics
Doostmohammadi, Amin; Shendruk, Tyler N.; Thijssen, Kristian; Yeomans, Julia M.
2017-05-01
Meso-scale turbulence is an innate phenomenon, distinct from inertial turbulence, that spontaneously occurs at low Reynolds number in fluidized biological systems. This spatiotemporal disordered flow radically changes nutrient and molecular transport in living fluids and can strongly affect the collective behaviour in prominent biological processes, including biofilm formation, morphogenesis and cancer invasion. Despite its crucial role in such physiological processes, understanding meso-scale turbulence and any relation to classical inertial turbulence remains obscure. Here we show how the motion of active matter along a micro-channel transitions to meso-scale turbulence through the evolution of locally disordered patches (active puffs) from an ordered vortex-lattice flow state. We demonstrate that the stationary critical exponents of this transition to meso-scale turbulence in a channel coincide with the directed percolation universality class. This finding bridges our understanding of the onset of low-Reynolds-number meso-scale turbulence and traditional scale-invariant turbulence in confinement.
Onset of meso-scale turbulence in living fluids
Doostmohammadi, Amin; Thijssen, Kristian; Yeomans, Julia M
2016-01-01
Meso-scale turbulence is an innate phenomenon, distinct from inertial turbulence, that spontaneously occurs at zero-Reynolds number in fluidized biological systems. This spatio-temporal disordered flow radically changes nutrient and molecular transport in living fluids and can strongly affect the collective behaviour in prominent biological processes, including biofilm formation, morphogenesis and cancer invasion. Despite its crucial role in such physiological processes, understanding meso-scale turbulence and any relation to classical inertial turbulence remains obscure. Here, we show how the motion of active matter along a micro-channel transitions to meso-scale turbulence through the evolution of disordered patches (active puffs) from an absorbing state of flow vortex-lattices. We demonstrate that the critical behaviour of this transition to meso-scale turbulence in a channel belongs to the directed percolation universality class. This finding bridges our understanding of the onset of zero-Reynolds number ...
Unifying Inference of Meso-Scale Structures in Networks.
Directory of Open Access Journals (Sweden)
Birkan Tunç
Full Text Available Networks are among the most prevalent formal representations in scientific studies, employed to depict interactions between objects such as molecules, neuronal clusters, or social groups. Studies performed at meso-scale that involve grouping of objects based on their distinctive interaction patterns form one of the main lines of investigation in network science. In a social network, for instance, meso-scale structures can correspond to isolated social groupings or groups of individuals that serve as a communication core. Currently, the research on different meso-scale structures such as community and core-periphery structures has been conducted via independent approaches, which precludes the possibility of an algorithmic design that can handle multiple meso-scale structures and deciding which structure explains the observed data better. In this study, we propose a unified formulation for the algorithmic detection and analysis of different meso-scale structures. This facilitates the investigation of hybrid structures that capture the interplay between multiple meso-scale structures and statistical comparison of competing structures, all of which have been hitherto unavailable. We demonstrate the applicability of the methodology in analyzing the human brain network, by determining the dominant organizational structure (communities of the brain, as well as its auxiliary characteristics (core-periphery.
Unifying Inference of Meso-Scale Structures in Networks.
Tunç, Birkan; Verma, Ragini
2015-01-01
Networks are among the most prevalent formal representations in scientific studies, employed to depict interactions between objects such as molecules, neuronal clusters, or social groups. Studies performed at meso-scale that involve grouping of objects based on their distinctive interaction patterns form one of the main lines of investigation in network science. In a social network, for instance, meso-scale structures can correspond to isolated social groupings or groups of individuals that serve as a communication core. Currently, the research on different meso-scale structures such as community and core-periphery structures has been conducted via independent approaches, which precludes the possibility of an algorithmic design that can handle multiple meso-scale structures and deciding which structure explains the observed data better. In this study, we propose a unified formulation for the algorithmic detection and analysis of different meso-scale structures. This facilitates the investigation of hybrid structures that capture the interplay between multiple meso-scale structures and statistical comparison of competing structures, all of which have been hitherto unavailable. We demonstrate the applicability of the methodology in analyzing the human brain network, by determining the dominant organizational structure (communities) of the brain, as well as its auxiliary characteristics (core-periphery).
Exchange effects in Coulomb quantum plasmas: Dispersion of waves in 2D and 3D mediums
Andreev, Pavel A
2014-01-01
We describe quantum hydrodynamic equations with the Coulomb exchange interaction for three and two dimensional plasmas. Explicit form of the force densities are derived. We present non-linear Schrodinger equations (NLSEs) for the Coulomb quantum plasmas with the exchange interaction. We show contribution of the exchange interaction in the dispersion of the Langmuir, and ion-acoustic waves. We consider influence of the spin polarization ratio on strength of the Coulomb exchange interaction. This is important since exchange interaction between particles with same spin direction and particles with opposite spin directions are different. At small particle concentrations $n_{0}>10^{25}cm^{-3}$ the Fermi pressure prevails over the exchange interaction for all polarizations. Similar picture we obtain for two dimensional quantum plasmas.
Micro- and meso-scale effects of forested terrain
DEFF Research Database (Denmark)
Dellwik, Ebba; Mann, Jakob; Sogachev, Andrey
2011-01-01
. Deviations from the requirement of homogeneity are often the focus of micro-scale studies in forested areas. Yet, to explain the wind climate in the relevant height range for turbines, it is necessary to also account for the length scales that are important parameters for the meso-scale flow. These length...... scales are the height of the planetary boundary layer and the Monin-Obukhov length, which both are related to the energy balance of the surface. Examples of important micro- and meso-scale effects of forested terrain are shown using data and model results from recent and ongoing experiments. For micro...
Lawrence-Doniach model in London approximation as a system of 2D Coulomb particles of two kinds
Energy Technology Data Exchange (ETDEWEB)
Artemov, A.N., E-mail: artemov@fti.dn.ua [Donetsk Physical and Technology Institute, Donetsk 83114 (Ukraine)
2011-12-15
We examine the Lawrence-Doniach model with Josephson coupling between layers. We represent the model as a system of 2D Coulomb particles of two kinds. The model was studied in the mean field and renormalization group approaches. The system investigated does not undergo a second order phase transition. Thermodynamical properties of layered superconductors with Josephson coupling in zero magnetic field are discussed. It is shown that the Lawrence-Doniach model of layered superconductors in the London approximation can be presented as a system of classical Coulomb particles of two kinds. This representation includes both Josephson and 2D vortex subsystems in absolutely symmetrical way. The model was analyzed by means of the real-space renormalization group approach and in the mean field approximation. It is found that there is no a second order phase transition in the system. Instead of this the model demonstrates the qualitative change of the system properties which can look as a phase transition for experimental purposes.
Optogenetic stimulation of a meso-scale human cortical model
Selvaraj, Prashanth; Szeri, Andrew; Sleigh, Jamie; Kirsch, Heidi
2015-03-01
Neurological phenomena like sleep and seizures depend not only on the activity of individual neurons, but on the dynamics of neuron populations as well. Meso-scale models of cortical activity provide a means to study neural dynamics at the level of neuron populations. Additionally, they offer a safe and economical way to test the effects and efficacy of stimulation techniques on the dynamics of the cortex. Here, we use a physiologically relevant meso-scale model of the cortex to study the hypersynchronous activity of neuron populations during epileptic seizures. The model consists of a set of stochastic, highly non-linear partial differential equations. Next, we use optogenetic stimulation to control seizures in a hyperexcited cortex, and to induce seizures in a normally functioning cortex. The high spatial and temporal resolution this method offers makes a strong case for the use of optogenetics in treating meso scale cortical disorders such as epileptic seizures. We use bifurcation analysis to investigate the effect of optogenetic stimulation in the meso scale model, and its efficacy in suppressing the non-linear dynamics of seizures.
Coulomb scattering in a 2D interacting electron gas and production of EPR pairs.
Saraga, D S; Altshuler, B L; Loss, Daniel; Westervelt, R M
2004-06-18
We propose a setup to generate nonlocal spin Einstein-Podolsky-Rosen pairs via pair collisions in a 2D interacting electron gas, based on constructive two-particle interference in the spin-singlet channel at the pi/2 scattering angle. We calculate the scattering amplitude via the Bethe-Salpeter equation in the ladder approximation and small r(s) limit and find that the Fermi sea leads to a substantial renormalization of the bare scattering process. From the scattering length, we estimate the current of spin-entangled electrons and show that it is within experimental reach.
Meso-scale modeling of a forested landscape
DEFF Research Database (Denmark)
Dellwik, Ebba; Arnqvist, Johan; Bergström, Hans;
2014-01-01
Meso-scale models are increasingly used for estimating wind resources for wind turbine siting. In this study, we investigate how the Weather Research and Forecasting (WRF) model performs using standard model settings in two different planetary boundary layer schemes for a forested landscape and how...... this performance is changed when enhancing the roughness by a factor four in one of the schemes. The model simulations were evaluated using data from a 138 m tall mast in southeastern Sweden, where an experiment with six sonic anemometers and standard meteorological instrumentation was performed 2010...
Modelling Meso-Scale Diffusion Processes in Stochastic Fluid Bio-Membranes
Rafii-Tabar, H
1999-01-01
The space-time dynamics of rigid inhomogeneities (inclusions) free to move in a randomly fluctuating fluid bio-membrane is derived and numerically simulated as a function of the membrane shape changes. Both vertically placed (embedded) inclusions and horizontally placed (surface) inclusions are considered. The energetics of the membrane, as a two-dimensional (2D) meso-scale continuum sheet, is described by the Canham-Helfrich Hamiltonian, with the membrane height function treated as a stochastic process. The diffusion parameter of this process acts as the link coupling the membrane shape fluctuations to the kinematics of the inclusions. The latter is described via Ito stochastic differential equation. In addition to stochastic forces, the inclusions also experience membrane-induced deterministic forces. Our aim is to simulate the diffusion-driven aggregation of inclusions and show how the external inclusions arrive at the sites of the embedded inclusions. The model has potential use in such emerging fields as...
Meso-scale available gravitational potential energy in the world oceans
Institute of Scientific and Technical Information of China (English)
FENG Yang; WANG Wei; HUANG Ruixin
2006-01-01
The pitfalls of applying the commonly used definition of available gravitational potential energy (AGPE) to the world oceans are re-examined. It is proposed that such definition should apply to the meso-scale problems in the oceans, not the global scale. Based on WOA98 climatological data, the meso-scale AGPE in the world oceans is estimated. Unlike previous results by Oort et al., the meso-scale AGPE is large wherever there is a strong horizontal density gradient. The distribution of meso-scale AGPE reveals the close connection between the baroclinic instability and the release of gravitational potential energy stored within the scale of Rossby deformation radius.
Green's Kernels and meso-scale approximations in perforated domains
Maz'ya, Vladimir; Nieves, Michael
2013-01-01
There are a wide range of applications in physics and structural mechanics involving domains with singular perturbations of the boundary. Examples include perforated domains and bodies with defects of different types. The accurate direct numerical treatment of such problems remains a challenge. Asymptotic approximations offer an alternative, efficient solution. Green’s function is considered here as the main object of study rather than a tool for generating solutions of specific boundary value problems. The uniformity of the asymptotic approximations is the principal point of attention. We also show substantial links between Green’s functions and solutions of boundary value problems for meso-scale structures. Such systems involve a large number of small inclusions, so that a small parameter, the relative size of an inclusion, may compete with a large parameter, represented as an overall number of inclusions. The main focus of the present text is on two topics: (a) asymptotics of Green’s kernels in domai...
Flame dynamics of a meso-scale heat recirculating combustor
Energy Technology Data Exchange (ETDEWEB)
Vijayan, V.; Gupta, A.K. [Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States)
2010-12-15
The dynamics of premixed propane-air flame in a meso-scale ceramic combustor has been examined here. The flame characteristics in the combustor were examined by measuring the acoustic emissions and preheat temperatures together with high-speed cinematography. For the small-scale combustor, the volume to surface area ratio is small and hence the walls have significant effect on the global flame structure, flame location and flame dynamics. In addition to the flame-wall thermal coupling there is a coupling between flame and acoustics in the case of confined flames. Flame-wall thermal interactions lead to low frequency flame fluctuations ({proportional_to}100 Hz) depending upon the thermal response of the wall. However, the flame-acoustic interactions can result in a wide range of flame fluctuations ranging from few hundred Hz to few kHz. Wall temperature distribution is one of the factors that control the amount of reactant preheating which in turn effects the location of flame stabilization. Acoustic emission signals and high-speed flame imaging confirmed that for the present case flame-acoustic interactions have more significant effect on flame dynamics. Based on the acoustic emissions, five different flame regimes have been identified; whistling/harmonic mode, rich instability mode, lean instability mode, silent mode and pulsating flame mode. (author)
Implementation of meso-scale radioactive dispersion model for GPU
Energy Technology Data Exchange (ETDEWEB)
Sunarko [National Nuclear Energy Agency of Indonesia (BATAN), Jakarta (Indonesia). Nuclear Energy Assessment Center; Suud, Zaki [Bandung Institute of Technology (ITB), Bandung (Indonesia). Physics Dept.
2017-05-15
Lagrangian Particle Dispersion Method (LPDM) is applied to model atmospheric dispersion of radioactive material in a meso-scale of a few tens of kilometers for site study purpose. Empirical relationships are used to determine the dispersion coefficient for various atmospheric stabilities. Diagnostic 3-D wind-field is solved based on data from one meteorological station using mass-conservation principle. Particles representing radioactive pollutant are dispersed in the wind-field as a point source. Time-integrated air concentration is calculated using kernel density estimator (KDE) in the lowest layer of the atmosphere. Parallel code is developed for GTX-660Ti GPU with a total of 1 344 scalar processors using CUDA. A test of 1-hour release discovers that linear speedup is achieved starting at 28 800 particles-per-hour (pph) up to about 20 x at 14 4000 pph. Another test simulating 6-hour release with 36 000 pph resulted in a speedup of about 60 x. Statistical analysis reveals that resulting grid doses are nearly identical in both CPU and GPU versions of the code.
Manufacturing Ultra-Precision Meso-scale Products by Coining
Energy Technology Data Exchange (ETDEWEB)
Seugling, R M; Davis, P J; Rickens, K; Osmer, J; Brinksmeier, E
2010-02-18
A method for replicating ultra-precision, meso-scale features onto a near-net-shape metallic blank has been demonstrated. The 'coining' technology can be used to imprint a wide range of features and/or profiles into two opposing surfaces. The instrumented system provides the ability to measure and control the product thickness and total thickness variation (TTV). The coining mechanism relies on kinematic principles to accurately and efficiently produce ultra-precision work pieces without the production of by products such as machining chips, or grinding swarf while preserving surface finish, material structure and overall form. Coining has been developed as a niche process for manufacturing difficult to machine, millimeter size components made from materials that may present hazardous conditions. In the case described in this paper a refractory metal part, tantalum (Ta) was produced with 4 {micro}m peak to valley 50 {micro}m special wavelength sine wave coined into the surface of 50 {micro}m blank. This technique shows promise for use on ductile materials that cannot be precision machined with conventional single crystal diamond tooling and/or has strict requirements on subsurface damage, surface impurities and grain structure. As a production process, it can be used to reduce manufacturing costs where large numbers of ultra-precision, repetitive designs are required and produce parts out of hazardous materials without generating added waste.
Meso-scale aurora within the expansion phase bulge
Directory of Open Access Journals (Sweden)
N. Partamies
2006-09-01
Full Text Available We present ground-based optical, riometer and magnetometer recordings together with Polar UVI and GOES magnetic field observations of a substorm that occurred over Canada on 24 November 1997. This event involved a clear optical onset followed by poleward motion of the aurora as a signature of an expanding auroral bulge. During the expansion phase, there were three distinct types of meso-scale (10–1000 km auroral structures embedded in the bulge: at first a series of equatorward moving auroral arcs, followed by a well-defined spiral pair, and finally north-south directed aurora (a streamer. The spirals occurred several minutes after the onset, and indicate a shear in the field-aligned current. The north-south aligned aurora that formed about 10 min after the onset suggest bursty bulk flow type flows taking place in the central plasma sheet. Polar UVI observations of the polar cap location indicate that the southward drifting arcs were associated with magnetospheric activity within closed field lines, while the auroral streamer was launched by the bulge reaching the polar cap boundary, i.e. the mid-tail reconnection starting on the open field lines. The riometer data imply high energy electron precipitation in the vicinity of the the poleward moving edge of the auroral bulge, starting at the onset and continuing until the formation of the north-south structure. In this paper, we examine this evolving auroral morphology within the context of substorm theories.
Meso-Scale Radioactive Dispersion Modelling using GPU
Sunarko; Suud, Zaki
2017-01-01
Lagrangian Particle Dispersion Method (LPDM) is applied to model atmospheric dispersion of radioactive material in a meso-scale of a few tens of kilometers for site study purpose. Empirical relationships are used to determine the dispersion coefficient for various atmospheric stabilities. Diagnostic 3-D wind field is created based on data from a meteorological station using mass-conservation principle. Particles imitating radioactive pollutant are dispersed in the wind-field as a point source. Time-integrated air concentration is calculated using kernel density estimator (KDE) in the lowest layer of the atmosphere. Parallel code is developed for GTX-660Ti GPU with a total of 1344 scalar processors using CUDA programming. Significant speedup of about 20 times is achieved compared to the serial version of the code while accuracy is kept at reasonable level. Only small differences in particle positions and grid doses are observed when using the same sets of random number and meteorological data in both CPU and GPU versions of the code.
MICRO-SEISMOMETERS VIA ADVANCED MESO-SCALE FABRICATION
Energy Technology Data Exchange (ETDEWEB)
Garcia, Caesar A; Onaran, Guclu; Avenson, Brad; Hall, Neal
2014-11-07
The Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) seek revolutionary sensing innovations for the monitoring of nuclear detonations. Performance specifications are to be consistent with those obtainable by only an elite few products available today, but with orders of magnitude reduction in size, weight, power, and cost. The proposed commercial innovation calls upon several technologies including the combination of meso-scale fabrication and assembly, photonics-based displacement / motion detection methods, and the use of digital control electronics . Early Phase II development has demonstrated verified and repeatable sub 2ng noise floor from 3Hz to 100Hz, compact integration of 3-axis prototypes, and robust deployment exercises. Ongoing developments are focusing on low frequency challenges, low power consumption, ultra-miniature size, and low cross axis sensitivity. We are also addressing the rigorous set of specifications required for repeatable and reliable long-term explosion monitoring, including thermal stability, reduced recovery time from mass re-centering and large mechanical shocks, sensitivity stability, and transportability. Successful implementation will result in small, hand-held demonstration units with the ability to address national security needs of the DOE/NNSA. Additional applications envisioned include military/defense, scientific instrumentation, oil and gas exploration, inertial navigation, and civil infrastructure monitoring.
Integrating Local Scale Drainage Measures in Meso Scale Catchment Modelling
Directory of Open Access Journals (Sweden)
Sandra Hellmers
2017-01-01
Full Text Available This article presents a methodology to optimize the integration of local scale drainage measures in catchment modelling. The methodology enables to zoom into the processes (physically, spatially and temporally where detailed physical based computation is required and to zoom out where lumped conceptualized approaches are applied. It allows the definition of parameters and computation procedures on different spatial and temporal scales. Three methods are developed to integrate features of local scale drainage measures in catchment modelling: (1 different types of local drainage measures are spatially integrated in catchment modelling by a data mapping; (2 interlinked drainage features between data objects are enabled on the meso, local and micro scale; (3 a method for modelling multiple interlinked layers on the micro scale is developed. For the computation of flow routing on the meso scale, the results of the local scale measures are aggregated according to their contributing inlet in the network structure. The implementation of the methods is realized in a semi-distributed rainfall-runoff model. The implemented micro scale approach is validated with a laboratory physical model to confirm the credibility of the model. A study of a river catchment of 88 km2 illustrated the applicability of the model on the regional scale.
Meso-scale modeling of irradiated concrete in test reactor
Energy Technology Data Exchange (ETDEWEB)
Giorla, A. [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Vaitová, M. [Czech Technical University, Thakurova 7, 166 29 Praha 6 (Czech Republic); Le Pape, Y., E-mail: lepapeym@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Štemberk, P. [Czech Technical University, Thakurova 7, 166 29 Praha 6 (Czech Republic)
2015-12-15
Highlights: • A meso-scale finite element model for irradiated concrete is developed. • Neutron radiation-induced volumetric expansion is a predominant degradation mode. • Confrontation with expansion and damage obtained from experiments is successful. • Effects of paste shrinkage, creep and ductility are discussed. - Abstract: A numerical model accounting for the effects of neutron irradiation on concrete at the mesoscale is detailed in this paper. Irradiation experiments in test reactor (Elleuch et al., 1972), i.e., in accelerated conditions, are simulated. Concrete is considered as a two-phase material made of elastic inclusions (aggregate) subjected to thermal and irradiation-induced swelling and embedded in a cementitious matrix subjected to shrinkage and thermal expansion. The role of the hardened cement paste in the post-peak regime (brittle-ductile transition with decreasing loading rate), and creep effects are investigated. Radiation-induced volumetric expansion (RIVE) of the aggregate cause the development and propagation of damage around the aggregate which further develops in bridging cracks across the hardened cement paste between the individual aggregate particles. The development of damage is aggravated when shrinkage occurs simultaneously with RIVE during the irradiation experiment. The post-irradiation expansion derived from the simulation is well correlated with the experimental data and, the obtained damage levels are fully consistent with previous estimations based on a micromechanical interpretation of the experimental post-irradiation elastic properties (Le Pape et al., 2015). The proposed modeling opens new perspectives for the interpretation of test reactor experiments in regards to the actual operation of light water reactors.
Formation of low-level meso-scale southwest jet during seasonal rainfall
Institute of Scientific and Technical Information of China (English)
赵平; 周秀骥
2001-01-01
The meso-scale feature and energy budget of a low-level southwest jet were analyzed using the data collected during the heavy rainfall events that occurred between July 20 ～ 27, 1998 over the basin of the Changjiang.And the dynamic mechanism for the formation and maintenance of the meso-scale low-level jet under the condition of the low-level heterogeneous large-scale south wind was investigated using a shallow water model. The results can explain the mechanism of the formation of the meso-scale jet in this event and the importance of the heterogeneous large-scale horizontal motion in the formation of the meso-scale jet.
Machining, Assembly, and Characterization of a Meso-Scale Double Shell Target
Energy Technology Data Exchange (ETDEWEB)
Bono, M J; Hibbard, R L
2003-10-21
Several issues related to the manufacture of precision meso-scale assemblies have been identified as part of an effort to fabricate an assembly consisting of machined polymer hemispherical shells and machined aerogel. The assembly, a double shell laser target, is composed of concentric spherical layers that were machined on a lathe and then assembled. This production effort revealed several meso-scale manufacturing techniques that worked well, such as the machining of aerogel with cutting tools to form low density structures, and the development of an assembly manipulator that allows control of the assembly forces to within a few milliNewtons. Limitations on the use of vacuum chucks for meso-scale components were also identified. Many of the lessons learned in this effort are not specific to double shell targets and may be relevant to the production of other meso-scale devices.
Guide to the meso-scale production of the copepod Acartia tonsa
Marchus, Nancy H.; Wilcox, Jeffrey A.
2007-01-01
This manual is intended as a guide for the daily production of a few million A. tonsa nauplii for feeding to marine vertebrates and invertebrates. This scale of production is greater than most research would require, but smaller than commercial production, hence the term meso-scale production. This manual will briefly describe the biology of Acartia tonsa Dana that is relevant to culture, the culture methodology for meso-scale production of their eggs and nauplii, the system co...
An integrated meso-scale numerical model of melting and solidification in laser welding
Duggan, G.; Tong, M.; Browne, D. J.
2012-01-01
The authors present an integrated numerical model for the simulation of laser spot welding of an aluminium alloy at meso-scale in 2D. This model deals with the melting of the parent materials which form the weld pool and the subsequent solidification of the liquid metal in the pool, during the welding process. The melting of the parent materials due to the applied heating power is an important phenomenon, which determines the conditions at the onset of solidification, such as the geometry of the weld pool and the distribution of the temperature field. An enthalpy method is employed to predict the melting during the heating phase of welding. A Gaussian distribution is used to model the heat input from the laser. Once the laser beam is switched off and the melting halts, solidification commences. The UCD front tracking model [1,2] for alloy solidification is applied to predict the advancement of the columnar dendritic front, and a volume-averaging formulation is used to simulate nucleation and growth of equiaxed dendrites. A mechanical blocking criterion is used to define dendrite coherency, and the columnar-to-equiaxed transition within the weld pool is predicted.
Meso-scale analysis of deformation wave heating in metalized solid explosive
Directory of Open Access Journals (Sweden)
Gonthier K.A.
2011-01-01
Full Text Available Deformation induced heating of reactive solids is a physically complex process. As such, the effects of meso-structure, component thermomechanical properties, component mass fractions, and porosity on their impact response is not well-understood. In this study, an explicit, 2-D, Lagrangian finite and discrete element technique is used to examine thermomechanical fields in metal-explosive (aluminum-HMX particle mixtures due to piston supported uniaxial deformation waves. The meso-scale description uses a plane strain, thermoelastic-viscoplastic and friction constitutive theory to describe the motion and deformation of individual particles, and an energy consistent, penalty based method to describe inter-particle contact. The deformation response of material having an initial solid volume fraction of ΦS0 = 0.835 is characterized for different metal mass fractions and wave strengths. Predictions indicate that the response can be classified into strength dominated and pressure dominated regions depending on wave strength. Average thermomechanical fields that define the macro-scale wave structure are found to differ both qualitatively and quantitatively between the two regions.
Shock Wave Propagation in Cementitious Materials at Micro/Meso Scales
2015-08-31
ABSTRACT 16. SECURITY CLASSIFICATION OF: Shock wave response of heterogeneous materials like cement and concrete is greatly influenced by the...2015 Approved for public release; distribution is unlimited. Shock Wave Propagation in Cementitious Materials at Micro/Meso Scales The views...Box 12211 Research Triangle Park, NC 27709-2211 shock propagation, micro and macro scales, finite element modeling REPORT DOCUMENTATION PAGE 11
Information processing in micro and meso-scale neural circuits during normal and disease states
Luongo, Francisco
Neural computation can occur at multiple spatial and temporal timescales. The sum total of all of these processes is to guide optimal behaviors within the context of the constraints imposed by the physical world. How the circuits of the brain achieves this goal represents a central question in systems neuroscience. Here I explore the many ways in which the circuits of the brain can process information at both the micro and meso scale. Understanding the way information is represented and processed in the brain could shed light on the neuropathology underlying complex neuropsychiatric diseases such as autism and schizophrenia. Chapter 2 establishes an experimental paradigm for assaying patterns of microcircuit activity and examines the role of dopaminergic modulation on prefrontal microcircuits. We find that dopamine type 2 (D2) receptor activation results in an increase in spontaneous activity while dopamine type 1 (D1) activation does not. Chapter 3 of this dissertation presents a study that illustrates how cholingergic activation normally produces what has been suggested as a neural substrate of attention; pairwise decorrelation in microcircuit activity. This study also shows that in two etiologicall distinct mouse models of autism, FMR1 knockout mice and Valproic Acid exposed mice, this ability to decorrelate in the presence of cholinergic activation is lost. This represents a putative microcircuit level biomarker of autism. Chapter 4 examines the structure/function relationship within the prefrontal microcircuit. Spontaneous activity in prefrontal microcircuits is shown to be organized according to a small world architecture. Interestingly, this architecture is important for one concrete function of neuronal microcircuits; the ability to produce temporally stereotyped patterns of activation. In the final chapter, we identify subnetworks in chronic intracranial electrocorticographic (ECoG) recordings using pairwise electrode coherence and dimensionality reduction
Development of meso-scale milling machine tool and its performance analysis
Institute of Scientific and Technical Information of China (English)
Hongtao LI; Xinmin LAI; Chengfeng LI; Zhongqin LIN; Jiancheng MIAO; Jun NI
2008-01-01
To overcome the shortcomings of current technologies for meso-scale manufacturing such as MEMS and ultra precision machining, this paper focuses on the investigations on the meso milling process with a miniaturized machine tool. First, the related technologies for the process mechanism studies are investigated based on the analysis of the characteristics of the meso milling process. An overview of the key issues is presented and research approaches are also proposed. Then, a meso-scale milling machine tool system is developed. The subsystems and their specifications are described in detail. Finally, some tests are conducted to evaluate the performance of the system. These tests consist of precision measurement of the positioning subsystem, the test for machining precision evaluation, and the experiments for machining mechanical parts with com-plex features. Through test analysis, the meso milling process with a miniaturized machine tool is proved to be feasible and applicable for meso manufacturing.
Meso-scale effects of tropical deforestation in Amazonia: preparatory LBA modelling studies
Directory of Open Access Journals (Sweden)
A. J. Dolman
Full Text Available As part of the preparation for the Large-Scale Biosphere Atmosphere Experiment in Amazonia, a meso-scale modelling study was executed to highlight deficiencies in the current understanding of land surface atmosphere interaction at local to sub-continental scales in the dry season. Meso-scale models were run in 1-D and 3-D mode for the area of Rondonia State, Brazil. The important conclusions are that without calibration it is difficult to model the energy partitioning of pasture; modelling that of forest is easier due to the absence of a strong moisture deficit signal. The simulation of the boundary layer above forest is good, above deforested areas (pasture poor. The models' underestimate of the temperature of the boundary layer is likely to be caused by the neglect of the radiative effects of aerosols caused by biomass burning, but other factors such as lack of sufficient entrainment in the model at the mixed layer top may also contribute. The Andes generate patterns of subsidence and gravity waves, the effects of which are felt far into the Rondonian area The results show that the picture presented by GCM modelling studies may need to be balanced by an increased understanding of what happens at the meso-scale. The results are used to identify key measurements for the LBA atmospheric meso-scale campaign needed to improve the model simulations. Similar modelling studies are proposed for the wet season in Rondonia, when convection plays a major role.
Key words. Atmospheric composition and structure (aerosols and particles; biosphere-atmosphere interactions · Meterology and atmospheric dynamics (mesoscale meterology
Analysis on the Meso-scale Characteristics of a Hail Process in Linyi Area
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
[Objective] The research aimed to study the meso-scale characteristics of a hail process in Linyi area. [Method] By comprehensively using MICAPS conventional observation data, automatic encryption ground station, MM5 model product and Doppler weather radar data, a strong convective hail weather process which happened in Shandong Peninsula and southeast of Shandong on May 30, 2010 was analyzed. The circulation background and physical mechanism of strong convection weather occurrence, the features of meso- an...
Meso-scale resolution for the definition of environmental flow standards in Mediterranean streams
Vezza, Paolo; Martinez-Capel, Francisco; Muñoz-Mas, Rafael; Comoglio, Claudio; Spairani, Michele; Koutrakis, Emmanuil; Sapounidis, Argyris
2013-04-01
The prediction of fish presence related to habitat characteristics is fundamental for the definition of environmental flows and habitat restoration measures. Meso-scale habitat models have been widely used in the context of water resources planning and management and demonstrated interesting potentials to assess freshwater fish distribution at a large spatial scale. In particular, the meso-scale approach allows rivers to be surveyed for longer stretches with a considerable representation of river habitats in comparison with more detailed models, and involves a large range of habitat descriptors. Moreover, machine learning techniques, such as random forest (RF), can be used to define multivariate habitat suitability criteria and capture the confounded effect of biotic and abiotic environmental variables. Data from three catchments located in the Mediterranean area (i.e., Júcar, Po and Nestos river basins located in Spain, Italy and Greece respectively) were used to develop habitat suitability criteria for threatened and endemic fish species. Fish data for model constructions were collected in reference sites, which were selected for their natural conditions of flow regime and habitat characteristics, and the resulting models described the habitat use by fish during their diurnal routine. Dataset dimension varied from 110 to 240 mesohabitat observations depending on the considered fish species. The RF algorithm provided an indicator of variables' importance and, using the variables' ranking, the best and the most parsimonious model was selected to define the lowest number of variables to be surveyed for future model applications. Our results indicated that RF performed well in both model calibration and validation phases and can be considered a valuable tool to predict fish distribution at meso-scale. Overall, the habitat suitability models had high model-fit accuracy (ranging from 75% to 94%). Cohen's kappa statistics were assessed over 0.52 and all models showed
Integrated Modeling and Experimental Studies at the Meso Scale for Advanced Reactive Materials
2016-07-01
problem (VRP) and vacuum tracking method for non-ideal EOS The vacuum Riemann problem (VRP) is by definition a Riemann problem with vacuum initial condition...T E C H N IC A L R E P O R T DTRA-TR-16-76 Integrated Modeling and Experimental Studies at the Meso- Scale for Advanced Reactive Materials...work in this grant was directed by Prof. D. Scott Stewart, (the Stewart-Group) and the experimental work and data collection was directed by Prof
Development of a Meso-Scale SMA-Based Torsion Actuator for Image-Guided Procedures.
Sheng, Jun; Gandhi, Dheeraj; Gullapalli, Rao; Simard, J Marc; Desai, Jaydev P
2017-02-01
This paper presents the design, modeling, and control of a meso-scale torsion actuator based on shape memory alloy (SMA) for image-guided surgical procedures. Developing a miniature torsion actuator is challenging, but it opens the possibility of significantly enhancing the robot agility and maneuverability. The proposed torsion actuator is bi-directionally actuated by a pair of antagonistic SMA torsion springs through alternate Joule heating and natural cooling. The torsion actuator is integrated into a surgical robot prototype to demonstrate its working performance in the humid environment under C-Arm CT image guidance.
Mesos-scale modeling of irradiation in pressurized water reactor concrete biological shields
Energy Technology Data Exchange (ETDEWEB)
Le Pape, Yann [ORNL; Huang, Hai [Idaho National Laboratory (INL)
2016-01-01
Neutron irradiation exposure causes aggregate expansion, namely radiation-induced volumetric expansion (RIVE). The structural significance of RIVE on a portion of a prototypical pressurized water reactor (PWR) concrete biological shield (CBS) is investigated by using a meso- scale nonlinear concrete model with inputs from an irradiation transport code and a coupled moisture transport-heat transfer code. RIVE-induced severe cracking onset appears to be triggered by the ini- tial shrinkage-induced cracking and propagates to a depth of > 10 cm at extended operation of 80 years. Relaxation of the cement paste stresses results in delaying the crack propagation by about 10 years.
MODELING OF MESO-SCALE STRUCTURES IN PARTICLE-FLUID SYSTEMS: THE EMMS/CFD APPROACH
Institute of Scientific and Technical Information of China (English)
Ning Yang; Wei Wang; Wei Ge; Jinghai Li
2005-01-01
Meso-scale structures existing in the form of particle-rich clusters, streamers or strands in circulating fluidized beds, and of ascending bubble plumes and descending liquid-rich vortices in bubble columns and slurry-bed reactors, as commonly observed, have played an important role in the macro-scale behavior of particle-fluid systems. These meso-scale structures span a wide range of length and time scales, and their origin, evolution and influence are still far from being well understood.Recent decades have witnessed the emergence of computer simulation of particle-fluid systems based on computational fluid dynamic (CFD) models. However, strictly speaking these models are far from mature and the complex nature of particle-fluid systems arising from the meso-scale structures has been posing great challenges to investigators. The reason may be that the current two-fluid models (TFM) are derived either from continuum mechanics by using different kinds of averaging techniques for the conservation equations of single-phase flow, or from the kinetic theory of gases in which the assumption of molecular chaos is employed, thereby losing sight of the meso-scale heterogeneity at the scale of computational cells and leading to inaccurate calculation of the interaction force between particles and fluids. For example, the overall drag force for particles in a cell is usually calculated from the empirical Wen & Yu/Ergun correlations,which should be suspected since these correlations were originally derived from homogeneous systems.Schemes to solve this problem for gas-particles systems may be classified into four categories. First, one could capture the detailed meso-scale structure information at the cell scale by employing the so-called direct numerical simulation (DNS) (Hu, 1996), the pseudo-particle modeling (PPM) (Ge & Li, 2003), or the Lattice-Boltzmann method (LBM) to track the interface between gas and particles. Second, refinement of the computational meshes may
Holland, Charles W; Nielsen, Peter L; Dettmer, Jan; Dosso, Stan
2012-02-01
Seabed geoacoustic variability is driven by geological processes that occur over a wide spectrum of space-time scales. While the acoustics community has some understanding of horizontal fine-scale geoacoustic variability, less than O(10(0)) m, and large-scale variability, greater than O(10(3)) m, there is a paucity of data resolving the geoacoustic meso-scale O(10(0)-10(3)) m. Measurements of the meso-scale along an ostensibly "benign" portion of the outer shelf reveal three classes of variability. The first class was expected and is due to horizontal variability of layer thicknesses: this was the only class that could be directly tied to seismic reflection data. The second class is due to rapid changes in layer properties and/or boundaries, occurring over scales of meters to hundreds of meters. The third class was observed as rapid variations of the angle/frequency dependent reflection coefficient within a single observation and is suggestive of variability at scales of meter or less. Though generally assumed to be negligible in acoustic modeling, the second and third classes are indicative of strong horizontal geoacoustic variability within a given layer. The observations give early insight into possible effects of horizontal geoacoustic variability on long-range acoustic propagation and reverberation.
Dynamics of bluff-body-stabilized lean premixed syngas flames in a meso-scale channel
Lee, Bok Jik
2016-07-15
Direct numerical simulations are conducted to investigate the dynamics of lean premixed syngas flames stabilized by a bluff-body in a meso-scale channel at near blow-off conditions, in order to provide fundamental insights into the physical mechanisms responsible for the critical phenomena. Flames in a two-dimensional meso-scale channel with a square flame holder are adopted as the model configuration, and a syngas mixture at an equivalence ratio of 0.5 with the CO:H ratio of 1 is considered. As the inlet velocity is increased, the initially stable steady flames undergo a transition to an unsteady mode of regular asymmetric fluctuation. When the inlet velocity is further increased, the flame is eventually blown off. Between the regular fluctuation mode and blow-off limit, there exists a narrow range of the inlet velocity where the flames exhibit periodic local extinction and recovery. Approaching further to the blow-off limit, the recovery mode fails to occur but the flame survives as a short kernel attached to the base of the bluff-body, until it is completely extinguished as the attached flames are gradually shrunk towards the bluff-body. The results are systematically compared with the hydrogen flame results reported in our earlier study. Examination of the characteristic time scales of relevant processes provided understanding of key mechanisms responsible for the observed differences, thereby allowing improved description of the local extinction and re-ignition dynamics that are critical to flame stabilization.
Kosch, Michael; Nozawa, Satonori; Yiu, Ho-Ching Iris; Anderson, Callum; Ogawa, Yasunobu; Howells, Vikki; Baddeley, Lisa; Aruliah, Anasuya; McWhirter, Ian; McCrea, I. W.; Fujii, Ryoichi
We report on observations of E-region neutral wind fields and their interaction with auroral precipitation at meso-scale spatial resolution. The EISCAT Svalbard radar was used to observe the ionospheric line-of-sight ion flows and temperatures in the E-and F-regions whilst scan-ning its beam. An all-sky optical Scanning Doppler Imager was used at 557.7 nm to observe thermospheric neutral line-of-sight winds and temperatures. High-latitude data from February 2010 are presented. In the case of an auroral arc, strong acceleration of the E-region neutral wind occurs within 10s of km to the arc on a time scale of 10s of minutes. We demonstrate through modelling that this effect cannot be explained by height changes in the 557.7 nm emis-sion layer. The most likely explanation seems to be greatly enhanced ion drag associated with the increased plasma density caused by the particle precipitation, and the localised ionospheric electric field associated with the Pedersen closure current of auroral arcs. Since Joule heat-ing occurs predominantly in the E-region, meso-scale variability in the thermosphere probably accounts for a significant under-estimation in the total energy dissipation.
MODELING OF MESO-SCALE STRUCTURES IN PARTICLE-FLUID SYSTEMS: THE EMMS/CFD APPROACH
Institute of Scientific and Technical Information of China (English)
Ning; Yang; Wei; Wang; Wei; Ge; Jinghai; Li
2005-01-01
Meso-scale structures existing in the form of particle-rich clusters, streamers or strands in circulating fluidized beds, and of ascending bubble plumes and descending liquid-rich vortices in bubble columns and slurry-bed reactors, as commonly observed, have played an important role in the macro-scale behavior of particle-fluid systems. These meso-scale structures span a wide range of length and time scales, and their origin, evolution and influence are still far from being well understood.Recent decades have witnessed the emergence of computer simulation of particle-fluid systems based on computational fluid dynamic (CFD) models. However, strictly speaking these models are far from mature and the complex nature of particle-fluid systems arising from the meso-scale structures has been posing great challenges to investigators. The reason may be that the current two-fluid models (TFM) are derived either from continuum mechanics by using different kinds of averaging techniques for the conservation equations of single-phase flow, or from the kinetic theory of gases in which the assumption of molecular chaos is employed, thereby losing sight of the meso-scale heterogeneity at the scale of computational cells and leading to inaccurate calculation of the interaction force between particles and fluids. For example, the overall drag force for particles in a cell is usually calculated from the empirical Wen & Yu/Ergun correlations,which should be suspected since these correlations were originally derived from homogeneous systems.Schemes to solve this problem for gas-particles systems may be classified into four categories. First, one could capture the detailed meso-scale structure information at the cell scale by employing the so-called direct numerical simulation (DNS) (Hu, 1996), the pseudo-particle modeling (PPM) (Ge & Li, 2003), or the Lattice-Boltzmann method (LBM) to track the interface between gas and particles. Second, refinement of the computational meshes may
Nishikawa, H.; Tachibana, Y.; Udagawa, Y.
2012-12-01
Although the influence of the anomalous midlatitude SST upon atmospheric local circulation has been getting common in particular over the Kuroshio and the Gulf Stream regions, observational studies on the influence of the Okhotsk Sea, which is to the north of the Kuroshio, upon the atmospheric local circulation is much less than those of the Kuroshio. The climate of the Okhotsk SST is very peculiar. Extremely cold SST spots, whose summertime SST is lower than 5 Celsius degrees, are formed around Kuril Islands. Because SSTs are generally determined by local air-sea interaction as well as temperature advection, it is very difficult to isolate only the oceanic influence upon the atmosphere. The SST in this cold spot is, however, dominated by the tidal mixing, which is independent of the atmospheric processes. This unique condition may ease the account for the oceanic influence only. Although the SST environment of the Okhotsk Sea is good for understanding the oceanic influence upon the atmosphere, only a few studies has been executed in this region because of the difficulty of observations by research vessels in this region, where territory problems between Japan and Russia is unsolved. Because of the scant of direct observation, the Okhotsk Sea was still mysterious. In 2006 August, GPS radiosonde observation was carried out by Russian research vessel Khromov in the Sea of Okhotsk by the cooperation between Japan and Russia, and strong SST gradient of about 7 Celsius degrees/10km was observed around the Kuril Islands. The purpose of this study is to demonstrate observational finding of meso-scale atmospheric anticyclonic circulation influenced by the cold oceanic spot around the Kuril Island. The summaries of the observation are as follows. Meso-scale atmospheric ageostrophic anticyclonic circulation in the atmospheric marine-boundary layer is observed in and around the cold spot. A high air pressure area as compared with other surrounding areas is also located at the
Diatoms as a fingerprint of sub-catchment contributions to meso-scale catchment runoff
Klaus, Julian; Wetzel, Carlos E.; Martinez-Carreras, Nuria; Ector, Luc; Pfister, Laurent
2014-05-01
In recent years, calls were made for new eco-hydrological approaches to improve understanding of hydrological processes. Recently diatoms, one of the most common and diverse algal groups that can be easily transported by flowing water due to their small size (~10-200 µm), were used to detect the onset and cessation of surface runoff to small headwater streams and constrain isotopic and hydro-chemical hydrograph separation methods. While the method showed its potential in the hillslope-riparian zone-stream continuum of headwater catchments, the behavior of diatoms and their use for hydrological process research in meso-scale catchments remains uncertain. Diatoms can be a valuable support for isotope and hydro-chemical tracer methods when these become ambiguous with increasing scale. Distribution and abundance of diatom species is controlled by various environmental factors (pH, soil type, moisture conditions, exposition to sunlight, etc.). We therefore hypothesize that species abundance and composition can be used as a proxy for source areas. This presentation evaluates the potential for diatoms to trace source-areas in the nested meso-scale Attert River basin (250 km2, Luxembourg, Europe). We sampled diatom populations in streamwater during one flood event in Fall 2011 in 6 sub-catchments and the basin outlet - 17 to 28 samples/catchment for the different sampling locations. Diatoms were classified and counted in every individual sample. In total more than 400 diatom species were detected. Ordination analysis revealed a clear distinction between communities sampled in different sub-catchments. The species composition at the catchment outlet reflects a mixing of the diatom composition originating from different sub-catchments. This data suggests that diatoms indeed can reflect the geographic origin of stream water at the catchment outlet. The centroids of the ordination analysis might be linked to the physiographic characteristics (geology and land use) of the
Meso-scale distribution of summer monsoon rainfall near the Western Ghats (India)
Patwardhan, S. K.; Asnani, G. C.
2000-04-01
The spatial distribution of southwest monsoon rainfall is studied over Maharashtra State (India), which includes part of the well-known Western Ghats mountain range, near its western boundary, running almost from north to south, perpendicular to the summer monsoon current in the lower troposphere. Meso-scale analysis of daily rainfall is performed for Maharashtra State, including the Western Ghats, for the two mid-monsoon months of July and August, during the 10-year period of 1971-1980. Strong and weak monsoon days were identified for the 5-year period of 1976-1980. The meso-scale pattern of average daily rainfall is obtained separately for strong and for weak monsoon conditions.All these average patterns show the following features: (i) the rainfall increases rapidly from the Arabian Sea coast close to the line of maximum height of the Western Ghats; (ii) there are two rainfall maxima corresponding to the two mountain peaks parallel to the coast line; (iii) between the two mountain peaks, there is a valley which is narrow at the western end (upwind end), broadening towards the east (on the downwind side). Ground contour height of the valley rises eastwards and ends as a part of the Deccan Plateau east of the Ghats. Here the valley opens out like a funnel with higher mountains flanking its two sides. In the valley, the rainfall increases from the coast up to the line of maximum height of the Ghats, and then decreases eastwards towards the plateau. The rainfall isopleths also take a funnel-shaped configuration. An interesting feature is that near the wider section of the valley funnel, there is a rainfall minimum and then the rainfall increases further eastwards on the downwind side. This feature of rainfall minimum is somewhat similar to the rainfall minimum reported by Asnani and Kinuthia (personal communication); Asnani (Asnani GC. 1993. Tropical Meteorology, Vol. I. Prof. G.C. Asnani: Pune, India; 603) attributed the rainfall minimum to the Bernoulli effect. A
The impact of forest regeneration on streamflow in 12 meso-scale humid tropical catchments
Directory of Open Access Journals (Sweden)
H. E. Beck
2013-03-01
Full Text Available Although regenerating forests make up an increasingly large portion of humid tropical landscapes, comparatively little is known of their water use and effects on streamflow (Q. Since the 1950s the island of Puerto Rico has experienced widespread abandonment of pastures and agricultural lands, followed by forest regeneration. This paper examines the possible impacts of forest regeneration on several Q metrics for 12 meso-scale catchments (23–346 km2; mean precipitation 1720–3422 mm yr−1 with long (33–51 yr and simultaneous records for Q, precipitation (P, potential evapotranspiration (PET, and land cover. A simple spatially-lumped, conceptual rainfall-runoff model that uses daily P and PET time series as inputs (HBV-light was used to simulate Q for each catchment. Annual time series of observed and simulated values of four Q metrics were calculated. A least-squares trend was fitted through annual time series of the residual difference between observed and simulated time series of each Q metric. From this the total cumulative change Â was calculated, representing the change in each metric after controlling for climate variability and water storage carry-over effects between years. Negative values of Â were found for most catchments and Q metrics, suggesting enhanced actual evapotranspiration overall following forest regeneration. However, correlations between changes in urban or forest area and values of Â were insignificant (p ≥ 0.389 for all Q metrics. This suggests there is no convincing evidence that changes in the chosen Q metrics in these Puerto Rican catchments can be ascribed to changes in urban or forest area. The present results are in line with previous studies of meso- and macro-scale (sub-tropical catchments, which generally found no significant change in Q that can be attributed to changes in forest cover. Possible explanations for the apparent lack of a clear signal may include: errors in the land-cover, climate, Q
Micro- and meso-scale pore structure in mortar in relation to aggregate content
Energy Technology Data Exchange (ETDEWEB)
Gao, Yun, E-mail: yun.gao@ugent.be [Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Technologiepark-Zwijnaarde 904, B-9052 Ghent (Belgium); De Schutter, Geert [Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Technologiepark-Zwijnaarde 904, B-9052 Ghent (Belgium); Ye, Guang [Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Technologiepark-Zwijnaarde 904, B-9052 Ghent (Belgium); Microlab, Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2628 CN Delft (Netherlands)
2013-10-15
Mortar is often viewed as a three-phase composite consisting of aggregate, bulk paste, and an interfacial transition zone (ITZ). However, this description is inconsistent with experimental findings because of the basic assumption that larger pores are only present within the ITZ. In this paper, we use backscattered electron (BSE) imaging to investigate the micro- and meso-scale structure of mortar with varying aggregate content. The results indicate that larger pores are present not only within the ITZ but also within areas far from aggregates. This phenomenon is discussed in detail based on a series of analytical calculations, such as the effective water binder ratio and the inter-aggregate spacing. We developed a modified computer model that includes a two-phase structure for bulk paste. This model interprets previous mercury intrusion porosimetry data very well. -- Highlights: •Based on BSE, we examine the HCSS model. •We develop the HCSS-DBLB model. •We use the modified model to interpret the MIP data.
Global and Meso-scale Thermospheric Neutral Wind Response to Geomagnetic Storm
Lu, G.; Conde, M.; Doornbos, E.
2015-12-01
This paper presents a case study of thermospheric response to the 5 April 2010 geomagnetic storm. The NCAR Thermosphere-Ionosphere-Mesosphere Electrodynamic General Circulation Model (TIMEGCM) is used to investigate thermospheric neutral wind variations during the storm, and the model results are validated through comparison with ground and space based observations. More specifically, we conduct detailed inter-comparison of the winds observed by scanning Doppler imagers (SDI) in Alaska with those derived from the TIMEGCM simulations in order to assess model's ability in reproducing the observed meso-scale wind field. The thermospheric winds obtained from the accelerometers on board the GOCE satellite are also used to validate the simulation results on a global scale. While globally the wind velocity tends to be smaller than ion drift velocity, locally the winds can exceed ion drifts and also blow in the different direction than the ions. We will discuss how the thermospheric winds affect the energetic coupling of the magnetosphere-ionosphere-thermosphere system in terms of Joule heating and field-aligned currents.
Mucin aggregation from a rod-like meso-scale model
Moreno, Nicolas; Perilla, Jairo E.; Colina, Coray M.; Lísal, Martin
2015-05-01
Dissipative particle dynamics, a meso-scale particle-based model, was used to study the aggregation of mucins in aqueous solutions. Concentration, strength of the mucin-water interactions, as well as the effects of size, shape, and composition of the model molecules were studied. Model proteins were represented as rod-like objects formed by coarse-grained beads. In the first model, only one type of beads formed the mucin. It was found that all the surfaces were available to form aggregates and the conformation of the aggregates was a function of the strength of the mucin-water interaction. With this model, the number of aggregates was unaffected by the initial position of the mucins in the simulation box, except for the lowest mucin concentration. In a more refined mucin model, two kinds of beads were used in the molecule in order to represent the existence of cysteine-like terminal groups in the actual molecule. With this new scheme, aggregation took place by the interaction of the terminal groups between model molecules. The kinetic analysis of the evolution of the number of aggregates with time was also studied for both mucin models.
Modelling daily sediment yield from a meso-scale catchment, a case study in SW Poland
Energy Technology Data Exchange (ETDEWEB)
Keesstra, S. D.; Schoorl, J.; Temme, A. J. A. M.
2009-07-01
For management purposes it is important to be able to assess the sediment yield of a catchment. however, at this moment models designed for estimating sediment yield are only capable to give either very detailed storm-based information or year averages. The storm-based models require input data that are not available for most catchment. However, models that estimate yearly averages, ignore a lot of other detailed information, like daily discharge and precipitation data. There are currently no models available that model sediment yield on the temporal scale of one day and the spatial scale of a meso-scale catchment, without making use of very detailed input data. To fill this scientific and management gap, landscape evolution model LAPSUS has been adapted to model sediment yield on a daily basis. This model has the water balance as a base. To allow calibration with the discharge at the outlet, a subsurface flow module has been added to the model. (Author) 12 refs.
Evaluation of Test Methods for Triaxially Braided Composites using a Meso-Scale Finite Element Model
Energy Technology Data Exchange (ETDEWEB)
Zhang, Chao
2015-10-01
The characterization of triaxially braided composite is complicate due to the nonuniformity of deformation within the unit cell as well as the possibility of the freeedge effect related to the large size of the unit cell. Extensive experimental investigation has been conducted to develop more accurate test approaches in characterizing the actual mechanical properties of the material we are studying. In this work, a meso-scale finite element model is utilized to simulate two complex specimens: notched tensile specimen and tube tensile specimen, which are designed to avoid the free-edge effect and free-edge effect induced premature edge damage. The full field strain data is predicted numerically and compared with experimental data obtained by Digit Image Correlation. The numerically predicted tensile strength values are compared with experimentally measured results. The discrepancy between numerically predicted and experimentally measured data, the capability of different test approaches are analyzed and discussed. The presented numerical model could serve as assistance to the evaluation of different test methods, and is especially useful in identifying potential local damage events.
Development of an Efficient Meso- scale Multi-phase Flow Solver in Nuclear Applications
Energy Technology Data Exchange (ETDEWEB)
Lee, Taehun [City Univ. (CUNY), NY (United States)
2015-10-20
The proposed research aims at formulating a predictive high-order Lattice Boltzmann Equation for multi-phase flows relevant to nuclear energy related application - namely, saturated and sub-cooled boiling in reactors, and liquid- liquid mixing and extraction for fuel cycle separation. An efficient flow solver will be developed based on the Finite Element based Lattice Boltzmann Method (FE- LBM), accounting for phase-change heat transfer and capable of treating multiple phases over length scales from the submicron to the meter. A thermal LBM will be developed in order to handle adjustable Prandtl number, arbitrary specific heat ratio, a wide range of temperature variations, better numerical stability during liquid-vapor phase change, and full thermo-hydrodynamic consistency. Two-phase FE-LBM will be extended to liquid–liquid–gas multi-phase flows for application to high-fidelity simulations building up from the meso-scale up to the equipment sub-component scale. While several relevant applications exist, the initial applications for demonstration of the efficient methods to be developed as part of this project include numerical investigations of Critical Heat Flux (CHF) phenomena in nuclear reactor fuel bundles, and liquid-liquid mixing and interfacial area generation for liquid-liquid separations. In addition, targeted experiments will be conducted for validation of this advanced multi-phase model.
Meso-scale circulation at the intermediate-depth east of Mindanao observed by Argo profiling floats
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The meso-scale circulation at the intermediate depth east of Mindanao is studied using Argo profiling floats observations. The trajectories and the parking-depth velocities of Argo floats show that the intermediate-depth circulation east of Mindanao contains significant meso-scale features that are highly variable both in space and in time. Both cyclonic and anticyclonic eddies at the intermediate depth (1000–2000 m) are indicated by the trajectories east of Mindanao. The mean tangential velocities of these eddies are about 10 cm/s at 2000 m and over 20 cm/s at 1000 m, which indicates that the geostrophic calculation may contain large errors due to the vigorous eddy activity at the reference levels. The analyses also suggest that these eddies might play an important role in mass and vorticity balances of the intermediate-depth circulation east of Mindanao.
Gilchrist, Christopher L; Ruch, David S; Little, Dianne; Guilak, Farshid
2014-12-01
Tissue and biomaterial microenvironments provide architectural cues that direct important cell behaviors including cell shape, alignment, migration, and resulting tissue formation. These architectural features may be presented to cells across multiple length scales, from nanometers to millimeters in size. In this study, we examined how architectural cues at two distinctly different length scales, "micro-scale" cues on the order of ∼1-2 μm, and "meso-scale" cues several orders of magnitude larger (>100 μm), interact to direct aligned neo-tissue formation. Utilizing a micro-photopatterning (μPP) model system to precisely arrange cell-adhesive patterns, we examined the effects of substrate architecture at these length scales on human mesenchymal stem cell (hMSC) organization, gene expression, and fibrillar collagen deposition. Both micro- and meso-scale architectures directed cell alignment and resulting tissue organization, and when combined, meso cues could enhance or compete against micro-scale cues. As meso boundary aspect ratios were increased, meso-scale cues overrode micro-scale cues and controlled tissue alignment, with a characteristic critical width (∼500 μm) similar to boundary dimensions that exist in vivo in highly aligned tissues. Meso-scale cues acted via both lateral confinement (in a cell-density-dependent manner) and by permitting end-to-end cell arrangements that yielded greater fibrillar collagen deposition. Despite large differences in fibrillar collagen content and organization between μPP architectural conditions, these changes did not correspond with changes in gene expression of key matrix or tendon-related genes. These findings highlight the complex interplay between geometric cues at multiple length scales and may have implications for tissue engineering strategies, where scaffold designs that incorporate cues at multiple length scales could improve neo-tissue organization and resulting functional outcomes.
Institute of Scientific and Technical Information of China (English)
Li-cheng WANG; Tamon UEDA
2009-01-01
A meso-scale truss network model was developed to predict chloride diffusion in concrete.The model regards concrete as a three-phase composite of mortar matrix,coarse aggregates,and the interfacial transition zone (ITZ) between the mortar matrix and the aggregates.The diffusion coefficient of chloride in the mortar and the ITZ can be analytically determined with only the water-to-cement ratio and volume fraction of fine aggregates.Fick's second law of diffusion was used as the governing equation for chloride diffusion in a homogenous medium (e.g.,mortar);it was discretized and applied to the truss network model.The solution procedure of the truss network model based on the diffusion law and the meso-scale composite structure of concrete is outlined.Additionally,the dependence of the diffusion coefficient of chloride in the mortar and the ITZ on exposure duration and temperature is taken into account to illustrate their effect on chloride diffusion coefficient.The numerical results show that the exposure duration and environmental temperature play important roles in the diffusion rate of chloride ions in concrete.It is also concluded that the meso-scale truss network model can be applied to chloride transport analysis of damaged (or cracked) concrete.
Study on circulation and meso-scale eddies in the South China Sea in summer of 1998
Institute of Scientific and Technical Information of China (English)
许建平; 薛惠洁; 侍茂崇; 刘增宏
2002-01-01
By using wide scope ADCP data which were got during SCSMEX (South China Sea Monsoon Experiment) period in the summer of 1998, and comparing these data with numerical modelling result, the distribution and variation characteristics of the circulation and meso-scale eddies in the South China Sea (SCS) were studied. The results show that: (1) in the SCS, 18 different scale eddies or motion systems with characteristics similar to meso-scale eddy were found during the investigation; (2) a strong westward current was found in the south of the Taiwan Shoal; (3) the energy of those eddies west of 114°E was much stronger than that of the east; and (4) there exist many powerful meso-scale eddies in the Nansha region south of 12°N. The distributions of numerous eddies reflect the complexity of the circulation in the SCS. It seems that the formation of those eddies should be caused by joint work of wind, coast feature, bottom topography, water density, inertial force and continental shelf waves.
Directory of Open Access Journals (Sweden)
Mateusz Szcześniak
2015-02-01
Full Text Available Ground-based precipitation data are still the dominant input type for hydrological models. Spatial variability in precipitation can be represented by spatially interpolating gauge data using various techniques. In this study, the effect of daily precipitation interpolation methods on discharge simulations using the semi-distributed SWAT (Soil and Water Assessment Tool model over a 30-year period is examined. The study was carried out in 11 meso-scale (119–3935 km2 sub-catchments lying in the Sulejów reservoir catchment in central Poland. Four methods were tested: the default SWAT method (Def based on the Nearest Neighbour technique, Thiessen Polygons (TP, Inverse Distance Weighted (IDW and Ordinary Kriging (OK. =The evaluation of methods was performed using a semi-automated calibration program SUFI-2 (Sequential Uncertainty Fitting Procedure Version 2 with two objective functions: Nash-Sutcliffe Efficiency (NSE and the adjusted R2 coefficient (bR2. The results show that: (1 the most complex OK method outperformed other methods in terms of NSE; and (2 OK, IDW, and TP outperformed Def in terms of bR2. The median difference in daily/monthly NSE between OK and Def/TP/IDW calculated across all catchments ranged between 0.05 and 0.15, while the median difference between TP/IDW/OK and Def ranged between 0.05 and 0.07. The differences between pairs of interpolation methods were, however, spatially variable and a part of this variability was attributed to catchment properties: catchments characterised by low station density and low coefficient of variation of daily flows experienced more pronounced improvement resulting from using interpolation methods. Methods providing higher precipitation estimates often resulted in a better model performance. The implication from this study is that appropriate consideration of spatial precipitation variability (often neglected by model users that can be achieved using relatively simple interpolation methods can
Meso-scale aeolian transport of beach sediment via dune blowout pathways within a linear foredune
O'Keeffe, Nicholas; Delgado-Fernandez, Irene; Jackson, Derek; Aplin, Paul; Marston, Christopher
2016-04-01
The evolution of coastal foredunes is largely controlled by sediment exchanges between the geomorphic sub-units of the nearshore, beach, foredune and dune field. Although blowouts are widely recognised as efficient sediment transport pathways, both event-scale and meso-scale quantification of their utility in transferring beach sediments landwards is limited. Foredunes characterised by multiple blowouts may be more susceptible to coastline retreat through the enhanced landwards transport of beach or foredune sediments. To date, a key constraint for investigations of such scenarios has been the absence of accurate blowout sediment transport records. Here we use the Sefton coast in north-west England as a study area where an unprecedented temporal coverage of LIDAR data is available between 1999 and 2015. Additionally, an extensive set of aerial photography also exists, dating back to 1945 allowing comparison of blowout frequency and magnitude together with the alongshore limits of coastline retreat. Digital terrain models are derived for each year that LIDAR data is available. Informed by LIDAR based topography and areas of bare sand (aerial photos) terrain models have been created containing individual blowouts. Differentials in 'z' values between each terrain model of each available year has identified topographic change and total levels of transport. Preliminary results have confirmed the importance of blowouts in transporting beach or foredune sediment landwards and thus potentially promoting coastline retreat. Repetition of processes across a larger number of blowout topographies will allow better identification of individual blowouts for 'event' scale field investigations to examine spatial and temporal variability of beach sediment transport via blowouts routes.
Meso-Scale Modeling of Spall in a Heterogeneous Two-Phase Material
Energy Technology Data Exchange (ETDEWEB)
Springer, Harry Keo [Univ. of California, Davis, CA (United States)
2008-07-11
The influence of the heterogeneous second-phase particle structure and applied loading conditions on the ductile spall response of a model two-phase material was investigated. Quantitative metallography, three-dimensional (3D) meso-scale simulations (MSS), and small-scale spall experiments provided the foundation for this study. Nodular ductile iron (NDI) was selected as the model two-phase material for this study because it contains a large and readily identifiable second- phase particle population. Second-phase particles serve as the primary void nucleation sites in NDI and are, therefore, central to its ductile spall response. A mathematical model was developed for the NDI second-phase volume fraction that accounted for the non-uniform particle size and spacing distributions within the framework of a length-scale dependent Gaussian probability distribution function (PDF). This model was based on novel multiscale sampling measurements. A methodology was also developed for the computer generation of representative particle structures based on their mathematical description, enabling 3D MSS. MSS were used to investigate the effects of second-phase particle volume fraction and particle size, loading conditions, and physical domain size of simulation on the ductile spall response of a model two-phase material. MSS results reinforce existing model predictions, where the spall strength metric (SSM) logarithmically decreases with increasing particle volume fraction. While SSM predictions are nearly independent of applied load conditions at lower loading rates, which is consistent with previous studies, loading dependencies are observed at higher loading rates. There is also a logarithmic decrease in SSM for increasing (initial) void size, as well. A model was developed to account for the effects of loading rate, particle size, matrix sound-speed, and, in the NDI-specific case, the probabilistic particle volume fraction model. Small-scale spall experiments were designed
A meso-scale model of the central and southern North Sea: Consequences of an improved resolution
Pohlmann, Thomas
2006-12-01
Results of a meso-scale model with a resolution of approximately 3 km of the central and southern North Sea are presented. The effect of the meso-scale resolution is depicted by comparing these results with data obtained from a 20 km resolution model. The validation of the model by means of observed SST data and of temperature data from a hydrographic transect demonstrates that the meso-scale model is able to reproduce the observations reasonably well. A comparison of the 3 km resolution results with 20 km results additionally shows that the large-scale model is not able to reproduce all the observed features of the SST with the same accuracy, in particular in the near-coastal areas along the Dutch and German coast. The parameters, which are investigated in more detail in this study, are temperature and salinity as well as the mean and eddy kinetic energy of the residual flow. The comparison between meso-scale and large-scale results demonstrates that not only the temperature and salinity distribution but also the kinetic energy is strongly affected by the chosen grid resolution. With respect to the generated mean kinetic energy of the residual flow the refined model resolution produces an increase up to 100% in the eastern parts of the North Sea, whereas in the Humber/Wash and Southern Bight region a decrease by up to 200% was obtained. In the northern part of the North Sea the finer resolution does not lead to large changes in the mean kinetic energy because here the large-scale features of the circulation dominate which also can be resolved by the large-scale model. This also explains that the mean kinetic energy differences between small- and large-scale model results are larger in summer than in winter because in winter due to the stronger winds the large-scale circulation is more dominant than in summer. The additional eddy kinetic energy of the residual flow (defined here as the kinetic energy contained in the spatial scales between 3 and 20 km) in general
Wurps, Hauke; Tambke, Jens; Steinfeld, Gerald; von Bremen, Lueder
2014-05-01
The development and design of wind energy converters for offshore wind farms require profound knowledge of the wind profile in the lower atmosphere. Especially an accurate and reliable estimation of turbulence, shear and veer are necessary for the prediction of energy production and loads. Currently existing wind energy turbines in the North Sea have hub heights of around 90 m and upper tip heights around 150 m, which is already higher than the highest measurement masts (e.g. FINO1: 103 m). The next generation of wind turbines will clearly outrange these altitudes, so the interest is to examine the atmosphere's properties above the North Sea up to 300 m. Therefore, besides the Prandtl layer also the Ekman layer has to be taken into account, which implies that changes of the wind direction with height become more relevant. For this investigation we use the Weather Research and Forecasting Model (WRF), a meso-scale numerical weather prediction system. In this study we compare different planetary boundary layer (PBL) schemes (MYJ, MYNN, QNSE) with the same high quality input from ECMWF used as boundary conditions (ERA-Interim). It was found in previous studies that the quality of the boundary conditions is crucially important for the accuracy of comparisons between different PBL schemes. This is due to the fact that the major source of meso-scale simulation errors is introduced by the driving boundary conditions and not by the different schemes of the meso-scale model itself. Hence, small differences in results from different PBL schemes can be distorted arbitrarily by coarse input data. For instance, ERA-Interim data leads to meso-scale RMSE values of 1.4 m/s at 100 m height above sea surface with mean wind speeds around 10 m/s, whereas other Reanalysis products lead to RMSEs larger than 2 m/s. Second, we compare our simulations to operational NWP results from the COSMO model (run by the DWD). In addition to the wind profile, also the turbulent kinetic energy (TKE
Design and fabrication of a meso-scale stirling engine and combustor.
Energy Technology Data Exchange (ETDEWEB)
Echekki, Tarek (Sandia National Laboratories, Livermore, CA); Haroldsen, Brent L. (Sandia National Laboratories, Livermore, CA); Krafcik, Karen L. (Sandia National Laboratories, Livermore, CA); Morales, Alfredo Martin (Sandia National Laboratories, Livermore, CA); Mills, Bernice E. (Sandia National Laboratories, Livermore, CA); Liu, Shiling (Sandia National Laboratories, Livermore, CA); Lee, Jeremiah C. (Sandia National Laboratories, Livermore, CA); Karpetis, Adionos N. (Sandia National Laboratories, Livermore, CA); Chen, Jacqueline H. (Sandia National Laboratories, Livermore, CA); Ceremuga, Joseph T. (Sandia National Laboratories, Livermore, CA); Raber, Thomas N. (Sandia National Laboratories, Livermore, CA); Hekmuuaty, Michelle A. (Sandia National Laboratories, Livermore, CA)
2005-05-01
Power sources capable of supplying tens of watts are needed for a wide variety of applications including portable electronics, sensors, micro aerial vehicles, and mini-robotics systems. The utility of these devices is often limited by the energy and power density capabilities of batteries. A small combustion engine using liquid hydrocarbon fuel could potentially increase both power and energy density by an order of magnitude or more. This report describes initial development work on a meso-scale external combustion engine based on the Stirling cycle. Although other engine designs perform better at macro-scales, we believe the Stirling engine cycle is better suited to small-scale applications. The ideal Stirling cycle requires efficient heat transfer. Consequently, unlike other thermodynamic cycles, the high heat transfer rates that are inherent with miniature devices are an advantage for the Stirling cycle. Furthermore, since the Stirling engine uses external combustion, the combustor and engine can be scaled and optimized semi-independently. Continuous combustion minimizes issues with flame initiation and propagation. It also allows consideration of a variety of techniques to promote combustion that would be difficult in a miniature internal combustion engine. The project included design and fabrication of both the engine and the combustor. Two engine designs were developed. The first used a cylindrical piston design fabricated with conventional machining processes. The second design, based on the Wankel rotor geometry, was fabricated by through-mold electroforming of nickel in SU8 and LIGA micromolds. These technologies provided the requisite precision and tight tolerances needed for efficient micro-engine operation. Electroformed nickel is ideal for micro-engine applications because of its high strength and ductility. A rotary geometry was chosen because its planar geometry was more compatible with the fabrication process. SU8 lithography provided rapid
Institute of Scientific and Technical Information of China (English)
XIA Changshui; JUNG KyungTae; WANG Guansuo; YIN Xunqiang; GUO Jingsong
2016-01-01
Meso-scale eddies are important features in the South China Sea (SCS). The eddies with diameters of 50–200 km can greatly impact the transport of heat, momentum, and tracers. A high-resolution wave-tide-circulation coupled model was developed to simulate the meso-scale eddy in the SCS in this study. The aim of this study is to examine the model ability to simulate the meso-scale eddy in the SCS without data assimilations The simulated Sea Surface Height (SSH) anomalies agree with the observed the AVISO SSH anomalies well. The simulated subsurface temperature profiles agree with the CTD observation data from the ROSE (Responses of Marine Hazards to climate change in the Western Pacific) project. The simulated upper-ocean currents also agree with the main circulation based on observations. A warm eddy is identified in winter in the northern SCS. The position and domain of the simulated eddy are confirmed by the observed sea surface height data from the AVISO. The result shows that the model has the ability to simulate the meso-scale eddy in the SCS without data assimilation. The three-dimensional structure of the meso-scale eddy in the SCS is analyzed using the model result. It is found that the eddy center is tilted vertically, which agrees with the observation. It is also found that the velocity center of the eddy does not coincide with the temperature center of the eddy. The result shows that the model has the ability to simulate the meso-scale eddy in the SCS without data assimilations. Further study on the forming mechanism and the three-dimensional structure of the meso-scale eddies will be carried out using the model result and cruise observation data in the near future.
Directory of Open Access Journals (Sweden)
Maché M.
2014-01-01
Full Text Available The object of the study is to present the first step of the development of a methodology that aims to merge the gap between meso scale and micro scale modelling. WRF simulations have been carried out in order to consider global wind conditions over a meso scale area of the future wind farm. A statistical analysis of the global wind data over several years has been carried out to initiate the work for the Saint Nazaire site. A focus was made on two wind regimes: the most common wind typical of the site's location and the extreme winds over the period. The WRF results were then used as initial conditions for a micro scale simulation carried out by a non-stationary large-eddy simulation (SOWFA tool based OpenFOAM solver that computes the flow around 2 turbines. Turbulence statistics were computed and analyzed. Fields of skewness and flatness show found that the distribution of turbulence becomes more homogeneous after the second turbine, while turbulence intensity increases.
Directory of Open Access Journals (Sweden)
Jennie Barron
2011-06-01
Full Text Available Meso-scale watershed management (1-10,000 km2 is receiving growing attention as the spatial scale where policy in integrated water resource management (IWRM goes into operational mode. This is also where aggregated field-level agricultural water management (AWM interventions may result in externalities. But there is little synthesised 'lessons learned' on the costs and benefits of interventions at this scale. Here we synthesise selected cases and meta-analyses on the investment cost in 'soft components' accompanying AWM interventions. The focus is on meso-scale watersheds in Asia, sub-Saharan Africa and Latin America. We found very few cases with benefit-to-cost evaluation at full project level, or separate costing of hard and soft components. The synthesis suggests higher development success rates in communities with an initial level of social capital, where projects were implemented with cost- and knowledge-sharing between involved stakeholders, and where one or more 'agents of change' were present to facilitate leadership and communications. There is a need to monitor and evaluate both the external and the internal gains and losses in a more systematic manner to help development agents and other investors to ensure wiser and more effective investments in AWM interventions and watershed management.
A dual theory of price and value in a meso-scale economic model with stochastic profit rate
Greenblatt, R. E.
2014-12-01
The problem of commodity price determination in a market-based, capitalist economy has a long and contentious history. Neoclassical microeconomic theories are based typically on marginal utility assumptions, while classical macroeconomic theories tend to be value-based. In the current work, I study a simplified meso-scale model of a commodity capitalist economy. The production/exchange model is represented by a network whose nodes are firms, workers, capitalists, and markets, and whose directed edges represent physical or monetary flows. A pair of multivariate linear equations with stochastic input parameters represent physical (supply/demand) and monetary (income/expense) balance. The input parameters yield a non-degenerate profit rate distribution across firms. Labor time and price are found to be eigenvector solutions to the respective balance equations. A simple relation is derived relating the expected value of commodity price to commodity labor content. Results of Monte Carlo simulations are consistent with the stochastic price/labor content relation.
Directory of Open Access Journals (Sweden)
R. Adams
2014-09-01
Full Text Available A model for simulating runoff pathways and water quality fluxes has been developed using the Minimum Information (MIR approach. The model, the Catchment Runoff Attenuation Tool (CRAFT is applicable to meso-scale catchments which focusses primarily on hydrological pathways that mobilise nutrients. Hence CRAFT can be used investigate the impact of management intervention strategies designed to reduce the loads of nutrients into receiving watercourses. The model can help policy makers, for example in Europe, meet water quality targets and consider methods to obtain "good" ecological status. A case study of the 414 km2 Frome catchment, Dorset UK, has been described here as an application of the CRAFT model. The model was primarily calibrated on ten years of weekly data to reproduce the observed flows and nutrient (nitrate nitrogen – N – and phosphorus – P concentrations. Also data from two years of sub-daily high resolution monitoring at the same site were also analysed. These data highlighted some additional signals in the nutrient flux, particularly of soluble reactive phosphorus, which were not observable in the weekly data. This analysis has prompted the choice of using a daily timestep for this meso-scale modelling study as the minimum information requirement. A management intervention scenario was also run to show how the model can support catchment managers to investigate how reducing the concentrations of N and P in the various flow pathways. This scale appropriate modelling tool can help policy makers consider a range of strategies to to meet the European Union (EU water quality targets for this type of catchment.
Combined macro-meso scale modeling of sintering. Part II, Mesoscale simulations
Energy Technology Data Exchange (ETDEWEB)
TIKARE,VEENA; OLEVSKY,EUGENE A.; BRAGINSKY,MICHAEL V.
2000-05-23
A mesoscale kinetic Monte Carlo model is presented to simulate microstructural evolution during sintering of 2D complex microstructures which evolves by grain growth, pore migration and densification. No assumptions about the geometry of the evolving microstructure are made. The results of these simulations are used to generate sintering stress and normalize viscous bulk modulus for use in continuum level simulation of sintering. The advantage of these simulations is that they can be used to generate more accurate parameters as various assumptions regarding geometry and transport mechanism are made. The previous companion paper used the results from the mesoscale simulations to simulate shrinkage and warpage in sintering of bilayer ceramics.
Tekleab, S.; Wenninger, J.W.; Uhlenbrook, S.
2014-01-01
Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin, as mo
Teklaeb, S.; Wenninger, J.W.; Uhlenbrook, S.
2013-01-01
Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stabl
Continuous formation of N-chloro-N,N-dialkylamine solutions in well-mixed meso-scale flow reactors
Jolley, Katherine E
2015-01-01
Summary The continuous flow synthesis of a range of organic solutions of N,N-dialkyl-N-chloramines is described using either a bespoke meso-scale tubular reactor with static mixers or a continuous stirred tank reactor. Both reactors promote the efficient mixing of a biphasic solution of N,N-dialkylamine in organic solvent, and aqueous sodium hypochlorite to achieve near quantitative conversions, in 72–100% in situ yields, and useful productivities of around 0.05 mol/h with residence times from 3 to 20 minutes. Initial calorimetric studies have been carried out to inform on reaction exotherms, rates and safe operation. Amines which partition mainly in the organic phase require longer reaction times, provided by the CSTR, to compensate for low mass transfer rates in the biphasic system. The green metrics of the reaction have been assessed and compared to existing procedures and have shown the continuous process is improved over previous procedures. The organic solutions of N,N-dialkyl-N-chloramines produced continuously will enable their use in tandem flow reactions with a range of nucleophilic substrates. PMID:26734089
Continuous formation of N-chloro-N,N-dialkylamine solutions in well-mixed meso-scale flow reactors.
Blacker, A John; Jolley, Katherine E
2015-01-01
The continuous flow synthesis of a range of organic solutions of N,N-dialkyl-N-chloramines is described using either a bespoke meso-scale tubular reactor with static mixers or a continuous stirred tank reactor. Both reactors promote the efficient mixing of a biphasic solution of N,N-dialkylamine in organic solvent, and aqueous sodium hypochlorite to achieve near quantitative conversions, in 72-100% in situ yields, and useful productivities of around 0.05 mol/h with residence times from 3 to 20 minutes. Initial calorimetric studies have been carried out to inform on reaction exotherms, rates and safe operation. Amines which partition mainly in the organic phase require longer reaction times, provided by the CSTR, to compensate for low mass transfer rates in the biphasic system. The green metrics of the reaction have been assessed and compared to existing procedures and have shown the continuous process is improved over previous procedures. The organic solutions of N,N-dialkyl-N-chloramines produced continuously will enable their use in tandem flow reactions with a range of nucleophilic substrates.
Directory of Open Access Journals (Sweden)
M. Thyssen
2008-06-01
Full Text Available Phytoplankton cells in the size range ~1–50 μm were analysed in surface waters using an automated flow cytometer, the Cytosub (http://www.cytobuoy.com, from the Azores to the French Brittany during spring 2007. The Cytosub records the pulse shape of the optical signals generated by phytoplankton cells when intercepted by the laser beam. A total of 6 distinct optical groups were resolved during the whole transect, and the high frequency sampling (15 min provided evidence for the cellular cycle (based on cyclic changes in cell size and fluorescence and distribution changes linked to the different water characteristics crossed in the north east Atlantic provinces. Nutrient concentrations and mixed layer depth varied from west to east, with a decrease in the mixed layer depth and high nutrient concentrations in the middle of the transect as well as near the French coast. Data provided a link between the sub meso scale processes and phytoplankton patchiness, some abundance variations due to the cellular cycle can be pointed out. The high frequency spatial sampling encompasses temporal variations of the phytoplankton abundance, offering a better insight into phytoplankton distribution.
Otwinowski, Matthew
1997-08-01
We have developed a computer model which describes the geochemical and physical processes responsible for acid drainage from waste rock piles. The model is in the form of coupled nonlinear PDEs which describe: the kinetics of the chemical reactions, the release of contaminants, the generation of energy due to the exothermic oxidation of sulphides, the diffusive and convective transport of oxygen and water, and the transport of energy by conduction and convection. The meso-scale and large-scale characterization of waste rock and waste rock piles is discussed. We show that long-term leaching rates are inversely proportional to the square of particle diameter and that the previously used models underestimate the particle size effect on long-term sulphide oxidation. Experimental data on rock fragmentation are used for a fractal statistical characterization of waste rock piles. The acid generation rates, oxygen consumption rates and temperature profiles have been determined for piles containing from fifty thousand to five hundred thousand tonnes of waste rock. The thermodynamic instabilities, which occur at certain critical values of pile height, are responsible for thermodynamic catastrophes which result in a rapid increase of acid generation rates. The critical height is determined by the values of sulphide concentration, particle size, pile porosity and other factors. The numerical code is based on the finite elements method with an adaptive grid generator. abstract.
Directory of Open Access Journals (Sweden)
Marcinkowski Paweł
2016-12-01
Full Text Available This study presents an application of the SWAT model (Soil and Water Assessment Tool in two meso-scale catchments in Poland (Upper Narew and Barycz, contrasting in terms of human pressures on water quantity and quality. The main objective was multi-variable and multi-site calibration and validation of the model against daily discharge, sediment and nutrient loads as well as discussion of challenges encountered in calibration phase. Multi-site calibration and validation gave varied results ranging from very good (daily discharge to acceptable (sediment, nitrogen and phosphorus loads in most of gauges and rather poor (individual gauges for all variables in both catchments. The calibrated models enabled spatial quantification of water yield, sediment and nutrient loads, indicating areas of special concern in terms of pollution, as well as estimation of contribution of pollution from different sources, indicating agriculture as the most important source in both catchments. During the calibration process a number of significant issues were encountered: (i global vs. local parametrization, (ii simulation of different pools of water quality parameters in reservoirs and streams and (iii underestimation of NO3-N loads in winter due to farmers practices. Discussion of these issues is hoped to aid SWAT model users in Poland in a deeper understanding of mechanisms of multi-variable and multi-site calibration.
Continuous formation of N-chloro-N,N-dialkylamine solutions in well-mixed meso-scale flow reactors
Directory of Open Access Journals (Sweden)
A. John Blacker
2015-12-01
Full Text Available The continuous flow synthesis of a range of organic solutions of N,N-dialkyl-N-chloramines is described using either a bespoke meso-scale tubular reactor with static mixers or a continuous stirred tank reactor. Both reactors promote the efficient mixing of a biphasic solution of N,N-dialkylamine in organic solvent, and aqueous sodium hypochlorite to achieve near quantitative conversions, in 72–100% in situ yields, and useful productivities of around 0.05 mol/h with residence times from 3 to 20 minutes. Initial calorimetric studies have been carried out to inform on reaction exotherms, rates and safe operation. Amines which partition mainly in the organic phase require longer reaction times, provided by the CSTR, to compensate for low mass transfer rates in the biphasic system. The green metrics of the reaction have been assessed and compared to existing procedures and have shown the continuous process is improved over previous procedures. The organic solutions of N,N-dialkyl-N-chloramines produced continuously will enable their use in tandem flow reactions with a range of nucleophilic substrates.
Alam, Zafir; Eastman, David; Jo, Minjea; Hemker, Kevin
2016-11-01
A high-temperature tensile tester (HTTT) has been established for the evaluation of micro-mechanical properties of materials at the meso-scale. Metals and ceramics can now be tested at temperatures and strain rates between room temperature and 1200°C and 10-5 s-1 to 10-1 s-1, respectively. The samples are heated in a compact clam shell furnace and strain is measured directly in the sample gage with digital image correlation. The HTTT extracts representative mechanical properties, as evidenced by the similarity in the evaluated micro-tensile properties of a solid solution-strengthened Ni-base superalloy Ni-625 with that of the bulk. The effectiveness of the HTTT has also been demonstrated in evaluating the tensile and stress relaxation/short-term creep properties of a polycrystalline Ni-base superalloy René 88DT. The versatility in carrying out tensile, short-term creep, bend tests, and fracture toughness measurements makes the HTTT a robust experimental tool for small-scale and scale-specific benchmarking of multi-scale ICME models.
Up-scaling of multi-variable flood loss models from objects to land use units at the meso-scale
Directory of Open Access Journals (Sweden)
H. Kreibich
2016-05-01
Full Text Available Flood risk management increasingly relies on risk analyses, including loss modelling. Most of the flood loss models usually applied in standard practice have in common that complex damaging processes are described by simple approaches like stage-damage functions. Novel multi-variable models significantly improve loss estimation on the micro-scale and may also be advantageous for large-scale applications. However, more input parameters also reveal additional uncertainty, even more in upscaling procedures for meso-scale applications, where the parameters need to be estimated on a regional area-wide basis. To gain more knowledge about challenges associated with the up-scaling of multi-variable flood loss models the following approach is applied: Single- and multi-variable micro-scale flood loss models are up-scaled and applied on the meso-scale, namely on basis of ATKIS land-use units. Application and validation is undertaken in 19 municipalities, which were affected during the 2002 flood by the River Mulde in Saxony, Germany by comparison to official loss data provided by the Saxon Relief Bank (SAB.In the meso-scale case study based model validation, most multi-variable models show smaller errors than the uni-variable stage-damage functions. The results show the suitability of the up-scaling approach, and, in accordance with micro-scale validation studies, that multi-variable models are an improvement in flood loss modelling also on the meso-scale. However, uncertainties remain high, stressing the importance of uncertainty quantification. Thus, the development of probabilistic loss models, like BT-FLEMO used in this study, which inherently provide uncertainty information are the way forward.
Crespo, Ariñe; Rodrigues, Marcos; Telletxea, Ibon; Ibáñez, Rubén; Díez, Felipe; Tobar, Joseba F; Arizaga, Juan
2016-01-01
Success of migration in birds in part depends on habitat selection. Overall, it is still poorly known whether there is habitat selection amongst landbird migrants moving across landscapes. Europe is chiefly covered by agro-forestry mosaic landscapes, so migratory species associated to either agricultural landscapes or woodland habitats should theoretically find suitable stopover sites along migration. During migration from wintering to breeding quarters, woodcocks (Scolopax rusticola) tagged with PTT satellite-tracking transmitters were used to test for the hypothesis that migrants associated to agro-forest habitats have no habitat selection during migration, at a meso-scale level. Using a GIS platform we extracted at a meso-scale range habitat cover at stopover localities. Results obtained from comparisons of soil covers between points randomly selected and true stopover localities sites revealed, as expected, the species may not select for particular habitats at a meso-scale range, because the habitat (or habitats) required by the species can be found virtually everywhere on their migration route. However, those birds stopping over in places richer in cropland or mosaic habitats including both cropland and forest and with proportionally less closed forest stayed for longer than in areas with lower surfaces of cropland and mosaic and more closed forest. This suggests that areas rich in cropland or mosaic habitat were optimal.
Energy Technology Data Exchange (ETDEWEB)
Serrato, M. G.
2013-09-27
The DOE Office of Environmental management (DOE EM) faces the challenge of decommissioning thousands of excess nuclear facilities, many of which are highly contaminated. A number of these excess facilities are massive and robust concrete structures that are suitable for isolating the contained contamination for hundreds of years, and a permanent decommissioning end state option for these facilities is in situ decommissioning (ISD). The ISD option is feasible for a limited, but meaningfull number of DOE contaminated facilities for which there is substantial incremental environmental, safety, and cost benefits versus alternate actions to demolish and excavate the entire facility and transport the rubble to a radioactive waste landfill. A general description of an ISD project encompasses an entombed facility; in some cases limited to the blow-grade portion of a facility. However, monitoring of the ISD structures is needed to demonstrate that the building retains its structural integrity and the contaminants remain entombed within the grout stabilization matrix. The DOE EM Office of Deactivation and Decommissioning and Facility Engineering (EM-13) Program Goal is to develop a monitoring system to demonstrate long-term performance of closed nuclear facilities using the ISD approach. The Savannah River National Laboratory (SRNL) has designed and implemented the In Situ Decommissioning Sensor Network, Meso-Scale Test Bed (ISDSN-MSTB) to address the feasibility of deploying a long-term monitoring system into an ISD closed nuclear facility. The ISDSN-MSTB goal is to demonstrate the feasibility of installing and operating a remote sensor network to assess cementitious material durability, moisture-fluid flow through the cementitious material, and resulting transport potential for contaminate mobility in a decommissioned closed nuclear facility. The original ISDSN-MSTB installation and remote sensor network operation was demonstrated in FY 2011-12 at the ISDSN-MSTB test cube
Marcinkowski, Pawel; Kardel, Ignacy; Ksiezniak, Marta; Berezowski, Tomasz; Okruszko, Tomasz; Mezghani, Abdelkader; Dobler, Andreas; Piniewski, Mikolaj
2016-04-01
The Upper Narew (4280 km2) and the Barycz (5520 km2) are two Polish, meso-scale, lowland catchments, contrasting in terms of land use, water management and water quality. Semi-distributed process-based SWAT model was applied in both catchments for assessment of climate change impact on selected water quality parameters. The model setup was developed based on high-resolution inputs, e.g. 5 km gridded precipitation and temperature dataset and 30 m Landsat8-based land cover map. Multi-site calibration and validation against observed discharge, sediment loads and nutrients loads (nitrogen and phosphorus compounds) gave predominantly satisfactory goodness-of-fit measures which enabled further model use for scenario analysis. Impact of land use on water quality can be assessed by comparing nutrients loads and concentrations simulated for the current conditions between two contrasting catchments. Both specific loads and concentrations of major nitrogen and phosphorous forms were on average 80-100% higher in the Barycz than in the Upper Narew catchment. This is a result of more intensive agricultural practices taking place in the Barycz, unlike the Upper Narew where agriculture is mostly extensive. Large parts of the Barycz catchment have been designed as the Nitrates Vulnerable Zones and since 2007 there are legal restrictions concerning agricultural practices in these areas. Nine GCM-RCM runs projected to the year 2100 for RCP 4.5 and 8.5 provided within the EURO-CORDEX experiment were first bias-corrected using quantile mapping method and then used as an ensemble of climate change scenarios in SWAT. Precipitation projections were largely consistent in showing an increasing precipitation trend, present particularly in winter and spring, in both catchments. This clearly affected the hydrological and biogeochemical cycle and resulted in higher projected water yield, increased erosion, and elevated nitrogen and phosphorus emission to water bodies. The rate of change caused
Vezza, Paolo; Comoglio, Claudio; Rosso, Maurizio
2010-05-01
The alterations of the natural flow regime and in-stream channel modification due to abstraction from watercourses act on biota through an hydraulic template, which is mediated by channel morphology. Modeling channel hydro-morphology is needed in order to evaluate how much habitat is available for selected fauna under specific environmental conditions, and consequently to assist decision makers in planning options for regulated river management. Meso-scale habitat modeling methods (e.g., MesoHABSIM) offer advantages over the traditional physical habitat evaluation, involving a larger range of habitat variables, allowing longer length of surveyed rivers and enabling understanding of fish behavior at larger spatial scale. In this study we defined a bottom-up method for the ecological discharge evaluation at regional scale, focusing on catchments smaller than 50 km2, most of them located within mountainous areas of Apennines and Alps mountain range in Piedmont (NW Italy). Within the regional study domain we identified 30 representative catchments not affected by water abstractions in order to build up the habitat-flow relationship, to be used as reference when evaluating regulated watercourses or new projects. For each stream we chose a representative reach and obtained fish data by sampling every single functional habitat (i.e. meso-habitat) within the site, keeping separated each area by using nets. The target species were brown trout (Salmo trutta), marble trout (Salmo trutta marmoratus), bullhead (Cottus gobius), chub (Leuciscus cephalus), barbel (Barbus barbus), vairone (Leuciscus souffia) and other rheophilic Cyprinids. The fish habitat suitability criteria was obtained from the observation of habitat use by a selected organism described with a multivariate relationship between habitat characteristics and fish presence. Habitat type, mean slope, cover, biotic choriotop and substrate, stream depth and velocity, water pH, temperature and percentage of dissolved
Ro, Y.; Kim, E.
2008-12-01
The East (Japan) Sea is drawing keen international attentions from broad spectrum of groups such as scientists, diplomats, and defense officers for its geopolitical situation, peculiar scientific assets recognized as miniature ocean. From physical oceanographic aspect, it is very rich with many features such as basin-wide circulation pattern, boundary currents, sub-polar front, meso-scale eddy activities and deep water formation. The circulation pattern in the East (Japan) Sea has been of major interests for its peculiar gyre, a western boundary current and its separation that resembles the currents such as Kuroshio and Gulf Stream. In relation to the gyre system in the East Sea, the formation of the East Korea Warm Current (EKWC) has brought up with many numerical experiments. Numerical experiments suggested a new idea to explain the formation of the EKWC in that the potential energy supply into the Ulleung Basin (UB) from the meso-scale eddy is a key process. This is closely linked with the baroclinic instability and the meandering of offshore component of Tsushima Warm Current. The UB has drawn attentions for its role of the formation of two major boundary currents, EKWC, North Korea Warm Current (NKCC), their interaction with the mesoscale UWE, watermass exchange between the Northern Japan Basin and UB. Numerical experiments along with hydrographic and other satellite datasets such as AVHRR, altimeter and ARGO profiles have been analyzed to understand the formation of the UWE. We found that the influence of the bottom topography and frictional forcing against lateral boundary are all closely associated with the sub-polar front. Meandering of the axis of the sub-polar front is closely linked with the separation point of the EKWC, Ulleung Warm Eddy, and other small and meso-scale eddies on the sub-polar front. These will be demonstrated with results of the numerical modeling experiments and animation movie will be presented.
Carrillo, J.; Redondo, J.; Fraunie, P.; Durand, N.
2003-04-01
This work presents the results of two laboratory and numerical experiments. The characteristic induced structures by stationer typical conditions from spring, summer, fall and winter. Laboratory experiences were developed on a five meters turntable (SINTEF facilities) obeys the Froude-Rossby similarities. While, the meso-escale numerical model was developed in the LSEET laboratory. This work evidences complementary results from the vortex sort characteristic by radius from both experimental and model methods. Additionally numerical model has a better representation from the conditions in the first 15km and the laboratory model represent the resolution between the large and the meso scale boundary.
Teklaeb, S.; J. W. Wenninger; S. Uhlenbrook
2013-01-01
Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stable isotope composition in precipitation, spring water and streamflow were analyzed (i) to characterize the spatial and temporal variations of water fluxes; (ii) to estimate the mean residence time o...
Hu, Y; Liu, H X; Wang, X; Shen, Z B; Li, P; Gu, C X; Gu, Y X; Lu, M M; Zhang, Q
2013-04-01
The meso-scale workpiece with greatly enhanced mechanical properties is potential to be widely used in the electronics productions and micro-electro mechanical systems. In this study, it demonstrates that the meso-scale cup-shape workpiece with good geometry can be obtained by a novel laser indirect shock forming method. After the forming process, the mechanical properties and microstructures of the formed workpiece were characterized. By transmission electron microscope observation, it was found that a mixed refined microstructure consisting of nano-scale twins embedded in nano-sized grains was produced at the center of the formed sample. Formation of these nanograins could be mainly attributed to two mechanisms: twin-twin intersections and twin∕matrix lamellae fragmentation. By nanoindentation tests, it reveals that the hardness of the sample has increased greatly after laser shock forming and the hardness increases with the laser energy. The elevated hardness originates from a considerable number of nano-scale twins and nanograins, which possess a pretty high strength due to the significant effects of grain boundary strengthening and twin boundary strengthening.
Institute of Scientific and Technical Information of China (English)
CHEN Qi; YAN Limin; ZHANG Hao; LI Guoxiu
2016-01-01
Electrical characteristics of a nozzle-attached meso-scale premixed methane-air flame under low-frequency AC (0-4300 V,0-500 Hz) and DC (0-3300 V) electric fields were studied.Ⅰ-Ⅴ curves were measured under different experimental conditions to estimate the magnitude of the total current 100-102 μA,the electron density 1015-1016 m-3 and further the power dissipation ≤ 0.7 W in the reaction zone.At the same time,the meso-scale premixed flame conductivity 10-4-10-3 Ω-1.m-1 as a function of voltage and frequency was experimentally obtained and was believed to represent a useful order-of magnitnde estimate.Moreover,the influence of the collision sheath relating to Debye length (31-98 μm) and the contamination layer of an active electrode on measurements was discussed,based on the combination of simulation and theoretical analysis.As a result,the electrode sheath dimension was evaluated to less than 0.5 mm,which indicatcd a complex effect of the collisiou sheath on the current measurements.The surface contamination effect of an active electrode was further analyzed using the SEM imaging method,which showed elements immigration during the contamination layer formation process.
Sato, K.
2015-12-01
Friction coefficients along faults control the brittle strength of the earth's upper crust, although it is difficult to estimate them especially of ancient geological faults. Several previous studies tried to determine the friction coefficient of meso-scale faults from their orientation distribution as follows. Fault-slip analysis through stress tensor inversion techniques gives principal stress axes and a stress ratio, which allows us to draw a normalized Mohr's circle. Assuming that a faulting occurs when the ratio of shear stress to normal stress on it, i.e., the slip tendency, exceeds the friction coefficient, one can find a linear boundary of distribution of points corresponding to faults on Mohr diagram. The slope of the boundary (friction envelope) provides the friction coefficient. This method has a difficulty in graphically and manually recognizing the linear boundary of distribution on the Mohr diagram. This study automated the determination of friction coefficient by considering the fluctuations of fluid pressure and differential stress. These unknown factors are expected to make difference in density of points representing faults on the Mohr diagram. Since the density is controlled by the friction coefficient, we can optimize the friction coefficient so as to explain the density distribution. The method was applied to two examples of natural meso-scale faults. The first example is from the Pleistocene Kazusa Group, central Japan, which filled a forearc basin of the Sagami Trough. Stress inversion analysis showed WNW-ENE trending tensional stress with a low stress ratio. The friction coefficient was determined to be around 0.66, which is typical value for sandstone. The Second example is from an underplated tectonic mélange in the Cretaceous to Paleogene Shimanto accretionary complex in southwest Japan along the Nankai Trough. The stress condition was determined to be an axial compression perpendicular to the foliation of shale matrix. The friction
Raghavan, Balaji; Niknezhad, Davood; Bernard, Fabrice; Kamali-Bernard, Siham
2016-09-01
The transport properties of cementitious composites such as concrete are important indicators of their durability, and are known to be heavily influenced by mechanical loading. In the current work, we use meso-scale hygro-mechanical modeling with a morphological 3D two phase mortar-aggregate model, in conjunction with experimentally obtained properties, to investigate the coupling between mechanical loading and damage and the permeability of the composite. The increase in permeability of a cylindrical test specimen at 28% aggregate fraction during a uniaxial displacement-controlled compression test at 85% of the peak load was measured using a gas permeameter. The mortar's mechanical behavior is assumed to follow the well-known compression damaged plasticity (CDP) model with isotropic damage, at varying thresholds, and obtained from different envelope curves. The damaged intrinsic permeability of the mortar evolves according to a logarithmic matching law with progressive loading. We fit the matching law parameters to the experimental result for the test specimen by inverse identification using our meso-scale model. We then subject a series of virtual composite specimens to quasi-static uniaxial compressive loading with varying boundary conditions to obtain the simulated damage and strain evolutions, and use the damage data and the previously identified parameters to determine the evolution of the macroscopic permeability tensor for the specimens, using a network model. We conduct a full parameter study by varying aggregate volume fraction, granulometric distribution, loading/boundary conditions and "matching law" parameters, as well as for different strain-damage thresholds and uniaxial loading envelope curves. Based on this study, we propose Avrami equation-based upper and lower bounds for the evolution of the damaged permeability of the composite.
Plasmons in Dimensionally Mismatched Coulomb Coupled Graphene Systems
DEFF Research Database (Denmark)
Badalyan, S. M.; Shylau, A. A.; Jauho, Antti-Pekka
2017-01-01
We calculate the plasmon dispersion relation for Coulomb coupled metallic armchair graphene nanoribbons and doped monolayer graphene. The crossing of the plasmon curves, which occurs for uncoupled 1D and 2D systems, is split by the interlayer Coulomb coupling into a lower and an upper plasmon...
Seismic images of ocean meso-scale eddies and internal waves%海洋中尺度涡与内波的地震图像
Institute of Scientific and Technical Information of China (English)
宋海斌; Luis Pinheiro; 王东晓; 董崇志; 宋洋; 拜阳
2009-01-01
海洋反射地震通常用于调查、研究海底地质构造,勘探油气与天然气水合物资源.近期研究表明多道反射地震方法也可以对水柱的热盐细结构成像.中尺度涡与内波是重要的物理海洋现象,但是常规的物理海洋调查是在间隔若干公里的离散测站上进行的,水平分辨率较低,因此对中尺度涡的结构与内波的横向分布了解较差.本文利用在大西洋东部、南海采集的地震数据给出了低频反射地震可以对中尺度涡与内波清晰成像的新的证据.反射地震方法较传统海洋观测手段,具有明显的优势,主要体现在高的水平分辨率和短时间内对整个海水剖面进行成像方面.从地震剖面上,能够清楚地观测到中尺度涡、内波造成的反射特征变化,从而有助于改进对能量在不同尺度的海水运动之间传递过程的认识.%Marine reflection seismics is usually used for imaging the seafloor geological structure and exploring hydrocarbon and gas hydrate resources.Recent researches have shown that multichannel seismic reflection method can also image the thermohaline fine structure in the water column.Meso-scale eddies and internal waves are important phenomena.Because conventional physical oceanographic measurements are carried out at discrete sites separated several kilometers with low lateral resolution,their lateral distribution is poorly known.This paper provides new evidence of clear seismic images of the meso-scale eddy in the eastern Atlantic Ocean and internal waves in the northeastern South China Sea.Compared with the traditional physical oceanographic methods,reflection seismology has several advantages,such as high lateral resolution and the ability of imaging a large ocean profile in short time.The change of reflection feature due to the meso-scale eddies and internal waves can be clearly imaged,which helps for better understanding of energy transfer among different scale process in the
Nakayama, H.; Takemi, T.; Nagai, H.
2015-06-01
A significant amount of radioactive material was accidentally discharged into the atmosphere from the Fukushima Dai-ichi Nuclear Power Plant from 12 March 2011, which produced high contaminated areas over a wide region in Japan. In conducting regional-scale atmospheric dispersion simulations, the computer-based nuclear emergency response system WSPEEDI-II developed by Japan Atomic Energy Agency was used. Because this system is driven by a meso-scale meteorological (MM) model, it is difficult to reproduce small-scale wind fluctuations due to the effects of local terrain variability and buildings within a nuclear facility that are not explicitly represented in MM models. In this study, we propose a computational approach to couple an LES-based CFD model with a MM model for detailed simulations of turbulent winds with buoyancy effects under real meteorological conditions using turbulent inflow technique. Compared to the simple measurement data, especially, the 10 min averaged wind directions of the LES differ by more than 30 degrees during some period of time. However, distribution patterns of wind speeds, directions, and potential temperature are similar to the MM data. This implies that our coupling technique has potential performance to provide detailed data on contaminated area in the nuclear accidents.
Directory of Open Access Journals (Sweden)
Jie Xu
2015-11-01
Full Text Available Micro-forming with ultrafine-grained (UFG materials is a promising direction for the fabrication of micro-electro-mechanical systems (MEMS components due to the improved formability, good surface quality, and excellent mechanical properties it provides. In this paper, micro-compression tests were performed using UFG pure aluminum processed by equal-channel angular pressing (ECAP with subsequent annealing treatment. Microstructural evolution was investigated by electron back-scattered diffraction (EBSD and transmission electron microscopy (TEM. The results show that microstructural evolutions during compression tests at the micro/meso-scale in UFG pure Al are absolutely different from the coarse-grained (CG materials. A lot of low-angle grain boundaries (LAGBs and recrystallized fine grains are formed inside of the original large grains in CG pure aluminum after micro-compression. By contrast, ultrafine grains are kept with few sub-grain boundaries inside the grains in UFG pure aluminum, which are similar to the original microstructure before micro-compression. The surface roughness and coordinated deformation ability can be signmicrostructure; micro/meso-forming; ultrafine grains; ECAP; aluminumificantly improved with UFG pure aluminum, which demonstrates that the UFG materials have a strong potential application in micro/meso-forming.
Coulomb drag in coherent mesoscopic systems
DEFF Research Database (Denmark)
Mortensen, Niels Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2001-01-01
, such as the random matrix theory, or by numerical simulations. We show that Coulomb drag is sensitive to localized states, which usual transport measurements do not probe. For chaotic 2D systems we find a vanishing average drag, with a nonzero variance. Disordered 1D wires show a finite drag, with a large variance......We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means...
Coulomb Thrusting Application Study
2006-01-20
this formation about the orbit radial direction. From this point on- wards, this will be referred to as the Coulomb tether regulation problem . These...m2 m2 (6.13) For the Coulomb tether regulation problem , L is taken as a sum of a constant reference length Lref and a small varying length δL...be noted that in the Coulomb tether regulation problem Lref is constant and the dif- ferential equation given in Eq. (6.13) is lin- earized by
Mul, M. L.; Savenije, H. H. G.; Uhlenbrook, S.
2009-04-01
Understanding hydrological processes in poorly or ungauged catchments is of utmost importance for the management of water resources. This paper shows that a high resolution time series of hydrological data (rainfall, evaporation and runoff) collected over a limited period of time (i.e. 1.5 years), can give a good picture of the hydrological processes occurring in a 25 km2 catchment in Tanzania (Vudee catchment). In addition, several techniques, incl. tracer and mapping studies, have been applied to identify flow paths and contribution from different sources. All this information was used for the development of a conceptual hydrological model. The conceptual model is based on the Lumped Elementary Watershed (LEW) concept, restructured for hourly time steps. An additional flux, representing the drainage into the neighbouring catchment, identified using a multi-method approach, increased the model performance significantly, particularly related to a recession curve occurring at high flows. This corroborates the assumption that there is water draining towards the neighbouring catchment. The model runs show that surface runoff only occurs during heavy rains or directly thereafter, which is consistent with results from hydrograph separation. Overall, the major part of the runoff is generated by groundwater. Moreover, the model shows that the unsaturated zone has a relatively large storage capacity. At the meso-scale, hydrological processes are governed by a sub-daily timescale. As a result, only a high resolution conceptual model is able to mimic the hydrological processes accurately. By applying the LEW model, incorporating the hydrological processes as observed in the catchment, a better understanding has been obtained of the dominant hydrological processes at this scale. This is a prerequisite for sustainable management of the water resources in a water scarce region.
Poeppl, R. E.; Keesstra, S. D.; Fuchs, S.; Seeger, M.; Bertsch, R.; Glade, T.
2012-04-01
Knowledge about connectivity relationships in fluvial systems is of major importance, especially for assessing geomorphic system response to human interference. In the field of geomorphology, previous connectivity concepts have primarily focused on the (dis)connecting effects of different landscape forms rather than considering the role of humans. The authors will introduce a conceptual model highlighting the importance of humans as (dis)connecting agents in fluvial systems. It will be further demonstrated that different spatial dimensions of connectivity are interrelated, since alterations in one distinct spatial dimension cause changes in another. The reflections are underpinned by presenting case study examples from small (1 - 10 km2) to meso-scale catchments (10 - 1,000 km2) in different environmental settings. Direct as well as indirect human impacts on fluvial systems lead to significant changes in different spatial dimensions of connectivity, consequently inducing geomorphic changes. The construction of dams, for example, leads to a significant reduction of connectivity in longitudinal direction which is followed by river bed erosion downstream of the dam. Lateral connectivity relationships are modified by major land use changes in the catchments, hence altering the river runoff and sediment dynamics. In this context, reforestation, for example, leads to channel narrowing as a result of lower peak flows and a decrease of lateral sediment input. Another case study example shows how gully development is influenced by the construction of dirt roads, since these features are altering flow routing and hence connectivity within the gully catchment. Moreover, an example will be presented demonstrating that connectivity relationships in fluvial systems also change with time due to self-organizing properties of the system.
Iqbal, Asif; Allan, Andrew; Zito, Rocco
2016-03-01
The study aims to develop an emission inventory (EI) approach and conduct an inventory for vehicular sources in Dhaka City, Bangladesh. A meso-scale modelling approach was adopted for the inventory; the factors that influence the emissions and the magnitude of emission variation were identified and reported on, which was an innovative approach to account emissions unlike the conventional inventory approaches. Two techniques for the emission inventory were applied, viz. (i) a combined top-down and bottom-up approach that considered the total vehicle population and the average diurnal on-road vehicle speed profile in the city and (ii) a bottom-up approach that accounted for road link-specific emissions of the city considering diurnal traffic volume and speed profiles of the respective roads. For the bottom-up approach, road link-specific detailed data were obtained through field survey in 2012, where mid-block traffic count of the day, vehicle speed profile, road network and congestion data were collected principally. The emission variances for the change in transport system characteristics (like change in fuel type, AC usage pattern, increased speed and reduced congestion/stopping) were predicted and analysed in this study; congestion influenced average speed of the vehicles, and fuel types in the vehicles were identified as the major stressors. The study performance was considered reasonable when comparing with the limited number of similar studies conducted earlier. Given the increasing trend of private vehicles each year coupled with increasing traffic congestion, the city is under threat of increased vehicular emissions unless a good management strategy is implemented. Although the inventory is conducted for Dhaka and the result may be important locally, the approach adopted in this research is innovative in nature to be followed for conducting research on other urban transport systems.
Kalecinski, Natacha; Haeffelin, Martial; Badosa, Jordi; Periard, Christophe
2013-04-01
Solar photovoltaic power is a predominant source of electrical power on Reunion Island, regularly providing near 30% of electrical power demand for a few hours per day. However solar power on Reunion Island is strongly modulated by clouds in small temporal and spatial scales. Today regional regulations require that new solar photovoltaic plants be combined with storage systems to reduce electrical power fluctuations on the grid. Hence cloud and solar irradiance forecasting becomes an important tool to help optimize the operation of new solar photovoltaic plants on Reunion Island. Reunion Island, located in the South West of the Indian Ocean, is exposed to persistent trade winds, most of all in winter. In summer, the southward motion of the ITCZ brings atmospheric instabilities on the island and weakens trade winds. This context together with the complex topography of Reunion Island, which is about 60 km wide, with two high summits (3070 and 2512 m) connected by a 1500 m plateau, makes cloudiness very heterogeneous. High cloudiness variability is found between mountain and coastal areas and between the windward, leeward and lateral regions defined with respect to the synoptic wind direction. A detailed study of local dynamics variability is necessary to better understand cloud life cycles around the island. In the presented work, our approach to explore the short-term solar irradiance forecast at local scales is to use the deterministic output from a meso-scale numerical weather prediction (NWP) model, AROME, developed by Meteo France. To start we evaluate the performance of the deterministic forecast from AROME by using meteorological measurements from 21 meteorological ground stations widely spread around the island (and with altitudes from 8 to 2245 m). Ground measurements include solar irradiation, wind speed and direction, relative humidity, air temperature, precipitation and pressure. Secondly we study in the model the local dynamics and thermodynamics that
Coulomb drag in the mesoscopic regime
DEFF Research Database (Denmark)
Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2002-01-01
We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....
Coulomb drag in the mesoscopic regime
DEFF Research Database (Denmark)
Mortensen, N.A.; Flensberg, Karsten; Jauho, Antti-Pekka
2002-01-01
We present a theory for Coulomb drag between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....
Directory of Open Access Journals (Sweden)
S. Tekleab
2013-08-01
Full Text Available Measurements of the stable isotopes oxygen-18 (18O and deuterium (2H were carried out in two meso-scale catchments, Chemoga (358 km2 and Jedeb (296 km2 south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stable isotope composition in precipitation, spring water and streamflow were analyzed (i to characterize the spatial and temporal variations of water fluxes; (ii to estimate the mean residence time of water using a sine wave regression approach; and (iii to identify runoff components using classical two component hydrograph separations at a seasonal time scale. The results show that the isotopic composition of precipitation exhibit marked seasonal variations, which suggests different sources of moisture generation for the rainfall in the study area. The Atlantic–Indian ocean, Congo basin, and the Sud swamps are the likely the potential moisture source areas during the main rainy (summer season. While, the Indian–Arabian, and Mediterranean Sea moisture source areas during little rain (spring, and dry (winter seasons. The spatial variation of the isotopic composition is affected by the amount effect and to less extent by altitude and temperature effects. A mean altitude effect of −0.12‰ (100 m−1 for 18O and −0.58‰ (100 m−1 for 2H were discernable in precipitation isotope composition. The seasonal variations of the isotopic signature of the spring water exhibit a damped response as compared to the river waters, which shows that the spring water has longer residence times than the river water. Results from the hydrograph separation at a seasonal time scale indicate the dominance of event water with an average of 71% and 64% of the total runoff during the wet season in the Chemoga and Jedeb catchment, respectively. The stable isotope compositions of streamflow samples were damped compared to the input function of precipitation for both catchments
van Rein, H.; Brown, C. J.; Quinn, R.; Breen, J.; Schoeman, D.
2011-07-01
Acoustic seabed classification is a useful tool for monitoring marine benthic habitats over broad-scales (>1 km 2) and meso-scales (10 m 2-1 km 2). Its utility in this context was evaluated using two approaches: by describing natural changes in the temporal distribution of marine biotopes across the broad-scale (4 km 2), and by attempting to detect specific experimentally-induced changes to kelp-dominated biotopes across the meso-scale (100 m 2). For the first approach, acoustic backscatter mosaics were constructed using sidescan sonar and multibeam echosounder data collected from Church Bay (Rathlin Island, Northern Ireland) in 1999, 2008 and 2009. The mosaics were manually segmented into acoustic facies, which were ground-truthed using a drop-video camera. Biotopes were classified from the video by multivariate exploratory analysis and cross-tabulated with the acoustic facies, showing a positive correlation. These results were integrated with bathymetric data to map the distribution of seven unique biotopes in Church Bay. Kappa analysis showed the biotope distribution was highly similar between the biotope maps, possibly due to the stability of bedforms shaped by the tidal regime around Rathlin Island. The greatest biotope change in this approach was represented by seasonal and annual changes in the growth of the seagrass, Zostera marina. In the second approach, sidescan sonar data were collected before and after the removal of 100 m 2 of kelp from three sites. Comparison of the data revealed no differences between the high-resolution backscatter imagery. It is concluded that acoustic seabed classification can be used to monitor change over broad- and meso-scales but not necessarily for all biotopes; its success depends on the type of acoustic system employed and the biological characteristics of the target biotope.
Coulomb gauge ghost propagator and the Coulomb form factor
Quandt, M; Chimchinda, S; Reinhardt, H
2008-01-01
The ghost propagator and the Coulomb potential are evaluated in Coulomb gauge on the lattice, using an improved gauge fixing scheme which includes the residual symmetry. This setting has been shown to be essential in order to explain the scaling violations in the instantaneous gluon propagator. We find that both the ghost propagator and the Coulomb potential are insensitive to the Gribov problem or the details of the residual gauge fixing, even if the Coulomb potential is evaluated from the A0--propagator instead of the Coulomb kernel. In particular, no signs of scaling violations could be found in either quantity, at least to well below the numerical accuracy where these violations were visible for the gluon propagator. The Coulomb potential from the A0-propagator is shown to be in qualitative agreement with the (formally equivalent) expression evaluated from the Coulomb kernel.
Coulomb gauge ghost propagator and the Coulomb form factor
Quandt, M.; Burgio, G.; Chimchinda, S.; Reinhardt, H.
The ghost propagator and the Coulomb potential are evaluated in Coulomb gauge on the lattice, using an improved gauge fixing scheme which includes the residual symmetry. This setting has been shown to be essential in order to explain the scaling violations in the instantaneous gluon propagator. We find that both the ghost propagator and the Coulomb potential are insensitive to the Gribov problem or the details of the residual gauge fixing, even if the Coulomb potential is evaluated from the A0 -propagator instead of the Coulomb kernel. In particular, no signs of scaling violations could be found in either quantity, at least to well below the numerical accuracy where these violations were visible for the gluon propagator. The Coulomb potential from the A0 -propagator is shown to be in qualitative agreement with the (formally equivalent) expression evaluated from the Coulomb kernel.
Maj, Radoslaw
2009-01-01
The correlation function of two identical particles - pions or kaons - interacting via Coulomb potential is computed. The particles are emitted from an anisotropic particle's source of finite lifetime. In the case of pions, the effect of halo is taken into account as an additional particle's source of large spatial extension. The relativistic effects are discussed in detail. The Bowler-Sinyukov procedure to remove the Coulomb interaction is carefully tested. In the absence of halo the procedure is shown to work very well even for an extremely anisotropic source. When the halo is taken into account the free correlation function, which is extracted by means of the Bowler-Sinyukov procedure, is distorted at small relative momenta but the source parameters are still correctly reproduced.
Traceable Coulomb Blockade Thermometry
Hahtela, Ossi; Kemppinen, Antti; Meschke, Matthias; Prunnila, Mika; Gunnarsson, David; Roschier, Leif; Penttila, Jari; Pekola, Jukka
2016-01-01
We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods, the numerical fitting of the full conductance curve and measuring the height of the conductance dip yield almost identical results. The complete uncertainty analysis shows that the relative expanded uncertainty (k = 2) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 1 %. A good agreement within the measurement uncertainty is experimentally demonstrated between the Coulomb blockade thermometer and a superconducting reference point device that has been directly calibrated against the Provisional Low Temperature Scale of 2000.
The Coulomb Branch of 3d N= 4 Theories
Bullimore, Mathew; Dimofte, Tudor; Gaiotto, Davide
2017-09-01
We propose a construction for the quantum-corrected Coulomb branch of a general 3d gauge theory with N=4 supersymmetry, in terms of local coordinates associated with an abelianized theory. In a fixed complex structure, the holomorphic functions on the Coulomb branch are given by expectation values of chiral monopole operators. We construct the chiral ring of such operators, using equivariant integration over BPS moduli spaces. We also quantize the chiral ring, which corresponds to placing the 3d theory in a 2d Omega background. Then, by unifying all complex structures in a twistor space, we encode the full hyperkähler metric on the Coulomb branch. We verify our proposals in a multitude of examples, including SQCD and linear quiver gauge theories, whose Coulomb branches have alternative descriptions as solutions to Bogomolnyi and/or Nahm equations.
Lieber, Michael
1989-06-01
It is something of a miracle that the nonrelativistic Schrodinger equation with a Coulomb potential can be solved for the wavefunction in exact analytic form. Even more miraculous is the result of Schwinger which enables the Green's function to be solved in closed form, for this is in effect, an infinite sum of wavefunction products. In the relativistic case too the wavefunction can be found in closed form, but as yet no such result for the Green's function has been found. This lecture provides a brief overview of the situation with an emphasis on the ``hidden symmetry'' which underlies the nonrelativisitic problem and its degenerate form which carries over to the relativistic case.
Plasmons in Dimensionally Mismatched Coulomb Coupled Graphene Systems
Badalyan, S. M.; Shylau, A. A.; Jauho, A. P.
2017-09-01
We calculate the plasmon dispersion relation for Coulomb coupled metallic armchair graphene nanoribbons and doped monolayer graphene. The crossing of the plasmon curves, which occurs for uncoupled 1D and 2D systems, is split by the interlayer Coulomb coupling into a lower and an upper plasmon branch. The upper branch exhibits an unusual behavior with end points at finite q . Accordingly, the structure factor shows either a single or a double peak behavior, depending on the plasmon wavelength. The new plasmon structure is relevant to recent experiments, its properties can be controlled by varying the system parameters and be used in plasmonic applications.
Traceable Coulomb blockade thermometry
Hahtela, O.; Mykkänen, E.; Kemppinen, A.; Meschke, M.; Prunnila, M.; Gunnarsson, D.; Roschier, L.; Penttilä, J.; Pekola, J.
2017-02-01
We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods are demonstrated: numerical fitting of the full conductance curve and measuring the height of the conductance dip. The complete uncertainty analysis shows that using either analysis method the relative combined standard uncertainty (k = 1) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 0.5%. In this temperature range, both analysis methods produced temperature estimates that deviated from 0.39% to 0.67% from the reference temperatures provided by a superconducting reference point device calibrated against the Provisional Low Temperature Scale of 2000.
Classical and quantum Coulomb crystals
Bonitz, M; Baumgartner, H; Henning, C; Filinov, A; Block, D; Arp, O; Piel, A; Kading, S; Ivanov, Y; Melzer, A; Fehske, H; Filinov, V
2008-01-01
Strong correlation effects in classical and quantum plasmas are discussed. In particular, Coulomb (Wigner) crystallization phenomena are reviewed focusing on one-component non-neutral plasmas in traps and on macroscopic two-component neutral plasmas. The conditions for crystal formation in terms of critical values of the coupling parameters and the distance fluctuations and the phase diagram of Coulomb crystals are discussed.
Coulomb blockade and Coulomb staircase behavior observed at room temperature
Uky Vivitasari, Pipit; Azuma, Yasuo; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka
2017-02-01
A single-electron transistor (SET) consists of source, drain, Coulomb island, and gate to modulate the number of electrons and control the current. For practical applications, it is important to operate a SET at room temperature. One proposal towards the ability to operate at room temperature is to decrease Coulomb island size down to a few nanometres. We investigate a SET using Sn-porphyrin (Sn-por) protected gold nanoparticles (AuNPs) with 1.4 nm in core diameter as a Coulomb island. The fabrication method of nanogap electrodes uses the combination of a top-down technique by electron beam lithography (EBL) and a bottom-up process through electroless gold plating (ELGP) as our group have described before. The electrical measurement was conducted at room temperature (300 K). From current-voltage (I d-V d) characteristics, we obtained clear Coulomb blockade phenomena together with a Coulomb staircase due to a Sn-por protected gold NP as a Coulomb island. Experimental results of I d-V d characteristics agree with a theoretical curve based on using the orthodox model. Clear dI d/dV d peaks are observed in the Coulomb staircase at 9 K which suggest the electron transports through excited energy levels of Au NPs. These results are a big step for obtaining SETs that can operate at room temperature.
2D semiconductor optoelectronics
Novoselov, Kostya
The advent of graphene and related 2D materials has recently led to a new technology: heterostructures based on these atomically thin crystals. The paradigm proved itself extremely versatile and led to rapid demonstration of tunnelling diodes with negative differential resistance, tunnelling transistors, photovoltaic devices, etc. By taking the complexity and functionality of such van der Waals heterostructures to the next level we introduce quantum wells engineered with one atomic plane precision. Light emission from such quantum wells, quantum dots and polaritonic effects will be discussed.
Activated sludge model No. 2d, ASM2d
DEFF Research Database (Denmark)
Henze, M.
1999-01-01
The Activated Sludge Model No. 2d (ASM2d) presents a model for biological phosphorus removal with simultaneous nitrification-denitrification in activated sludge systems. ASM2d is based on ASM2 and is expanded to include the denitrifying activity of the phosphorus accumulating organisms (PAOs...
Coulomb explosion of "hot spot"
Oreshkin, V I; Chaikovsky, S A; Artyomov, A P
2016-01-01
The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed and estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.
Institute of Scientific and Technical Information of China (English)
杜修力; 金浏
2015-01-01
钢筋锈蚀膨胀引起保护层混凝土开裂是影响钢筋混凝土结构耐久性和服役寿命的重要因素。考虑到混凝土细观结构组成对保护层破坏模式的影响，从细观角度出发，将混凝土看作由骨料、砂浆基质及两者间界面过渡区组成的三相复合材料，建立了描述钢筋锈胀力学行为的混凝土随机骨料模型。采用塑性损伤本构关系模型来表征砂浆基质和过渡区界面的力学行为，假定钢筋均匀锈蚀，对钢筋锈胀引起的混凝土保护层开裂破坏过程进行了细观数值研究。对比了宏观均匀模型与细观非均质模型下获得的保护层破坏模式，探讨了径厚比(c/d)、钢筋位置(中部和角区)及混凝土拉伸强度对保护层破坏模式及保护层胀裂时钢筋锈蚀水平的影响，得到了一些有益结论。%Concrete cover cracking induced by corrosion of steel reinforcement is a major influencing factor for durability and service-ability of reinforced concrete (RC)structures.Here in the study,the influence of concrete meso-structure on the failure pattern of concrete cover is accounted for.At the meso-scale, the concrete is assumed to be a three-phase composite composed of aggregate,mortar matrix and the interfacial transition zone (ITZ).A random aggregate structure of concrete is established for the study on the mechanical behavior of cover subjected to corrosion expansion of steel reinforcement.In the simulations,the plasticity damaged model is used to describe the mechanical behavior of the mortar matrix and the ITZ,and it is assumed that the corrosion of steel reinforcement is uniform.Based on the above assumptions,the cracking of concrete cover due to steel reinforcement corrosion is numerically simulated.The failure patterns obtained from the macro-scale homogeneous model and the present meso-scale heterogeneous model are compared.The effects of the ratio of cover thickness and reinforce-ment diameter (i
Iguchi, T.; Nakajima, T.; Khain, A. P.; Saito, K.; Takemura, T.; Okamoto, H.; Nishizawa, T.; Tao, W.-K.
2012-01-01
Equivalent radar reflectivity factors (Ze) measured by W-band radars are directly compared with the corresponding values calculated from a three-dimensional non-hydrostatic meso-scale model coupled with a spectral-bin-microphysical (SBM) scheme for cloud. Three case studies are the objects of this research: one targets a part of ship-borne observation using 95 GHz Doppler radar over the Pacific Ocean near Japan in May 2001; other two are aimed at two short segments of space-borne observation by the cloud profiling radar on CloudSat in November 2006. The numerical weather prediction (NWP) simulations reproduce general features of vertical structures of Ze and Doppler velocity. A main problem in the reproducibility is an overestimation of Ze in ice cloud layers. A frequency analysis shows a strong correlation between ice water contents (IWC) and Ze in the simulation; this characteristic is similar to those shown in prior on-site studies. From comparing with the empirical correlations by the prior studies, the simulated Ze is overestimated than the corresponding values in the studies at the same IWC. Whereas the comparison of Doppler velocities suggests that large-size snowflakes are necessary for producing large velocities under the freezing level and hence rules out the possibility that an overestimation of snow size causes the overestimation of Ze. Based on the results of several sensitivity tests, we conclude that the source of the overestimation is a bias in the microphysical calculation of Ze or an overestimation of IWC. To identify the source of the problems needs further validation research with other follow-up observations.
Coulomb interaction in multiple scattering theory
Ray, L.; Hoffmann, G. W.; Thaler, R. M.
1980-10-01
The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+208Pb elastic scattering and compared with experimental data. NUCLEAR REACTIONS 208Pb(p, p), E=0.8 GeV, Kerman, McManus, and Thaler, and Watson multiple scattering theories, Coulomb correction terms, high momentum transfer.
A Peristaltic Meso-Scale Mixer
Bau, Haim; Yi, Mingqiang; Hu, Howard H.
2000-11-01
In recent years, there has been a growing interest in developing minute laboratories on a "chip". Often, in order to facilitate chemical and biological reactions, one needs to mix various reagents and chemicals. Although the characteristic lengths associated with micro-devices are small, typically on the order of 100mm, in the case of large molecules, diffusion alone does not provide a sufficiently rapid means for mixing. Recent experimental[1] and theoretical[2] studies suggested the use of surface waves to induce peristaltic motion and enhance fluid stirring. We considered incompressible, viscous fluid confined in a rectangular cavity. One or two of the cavity walls were made of a thin membrane. Electric conductors were printed on the membrane. By passing appropriately phased alternating electric currents through these conductors in the presence of a magnetic field, relatively large amplitude travelling waves could be transmitted in cavity's walls and induce peristaltic motion. We describe the results of a theoretical study. We extended Selverov and Stone[2] theory to account for the presence of lateral boundaries. The induced velocity profiles were determined analytically for small amplitude waves (e) and numerically for waves of arbitrary amplitude. The effect of the peristaltic motion on the stretching and deformation of material lines were quantified. The work was supported, in part, by DARPA through grant N66001-97-1-8911 to the University of Pennsylvania. [1] Moroney, R. M., White, R., M., Howe, R., T., 1991, Ultrasonically Induced Microtransport, Proceedings IEEE Workshop Micro Electro Mechanical Systems, MEMS 95 Amsterdam, 277-282. [2] Selverov, K., and Stone, H., A., 2000, Peristaltically Driven Flows for Micro Mixers, to appear in Physics of Fluids.
No confinement without Coulomb confinement
Zwanziger, D
2003-01-01
We compare the physical potential $V_D(R)$ of an external quark-antiquark pair in the representation $D$ of SU(N), to the color-Coulomb potential $V_{\\rm coul}(R)$ which is the instantaneous part of the 44-component of the gluon propagator in Coulomb gauge, $D_{44}(\\vx,t) = V_{\\rm coul}(|\\vx|) \\delta(t)$ + (non-instantaneous). We show that if $V_D(R)$ is confining, $\\lim_{R \\to \\infty}V_D(R) = + \\infty$, then the inequality $V_D(R) \\leq - C_D V_{\\rm coul}(R)$ holds asymptotically at large $R$, where $C_D > 0$ is the Casimir in the representation $D$. This implies that $ - V_{\\rm coul}(R)$ is also confining.
Diriken, J.; Stefanescu, I.; Balabanski, D.; Blasi, N.; Blazhev, A.; Bree, N.; Cederkaell, J.; Cocolios, T. E.; Davinson, T.; Eberth, J.; Ekstrom, A.; Fedorov, D. V.; Fedosseev, V. N.; Fraile, L. M.; Franchoo, S.; Georgiev, G.; Gladnishki, K.; Huyse, M.; Ivanov, O. V.; Ivanov, V. S.; Iwanicki, J.; Jolie, J.; Konstantinopoulos, T.; Kroell, Th.; Kruecken, R.; Koester, U.; Lagoyannis, A.; Lo Bianco, G.; Maierbeck, P.; Marsh, B. A.; Napiorkowski, P.; Patronis, N.; Pauwels, D.; Reiter, P.; Seliverstov, M.; Sletten, G.; Van de Walle, J.; Van Duppen, P.; Voulot, D.; Walters, W. B.; Warr, N.; Wenander, F.; Wrzosek, K.
2010-01-01
The B(E2; I-i -> I-f) values for transitions in Ga-71(31)40 and Ga-73(31)42 were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of Ga-71,Ga-73 at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were dete
Coulomb drag in quantum circuits
Levchenko, Alex; Kamenev, Alex
2008-01-01
We study drag effect in a system of two electrically isolated quantum point contacts (QPC), coupled by Coulomb interactions. Drag current exhibits maxima as a function of QPC gate voltages when the latter are tuned to the transitions between quantized conductance plateaus. In the linear regime this behavior is due to enhanced electron-hole asymmetry near an opening of a new conductance channel. In the non-linear regime the drag current is proportional to the shot noise of the driving circuit,...
Regnery, Julia; Lee, Jonghyun; Drumheller, Zachary W.; Drewes, Jörg E.; Illangasekare, Tissa H.; Kitanidis, Peter K.; McCray, John E.; Smits, Kathleen M.
2017-05-01
Meaningful model-based predictions of water quality and quantity are imperative for the designed footprint of managed aquifer recharge installations. A two-dimensional (2D) synthetic MAR system equipped with automated sensors (temperature, water pressure, conductivity, soil moisture, oxidation-reduction potential) and embedded water sampling ports was used to test and model fundamental subsurface processes during surface spreading managed aquifer recharge operations under controlled flow and redox conditions at the meso-scale. The fate and transport of contaminants in the variably saturated synthetic aquifer were simulated using the finite element analysis model, FEFLOW. In general, the model concurred with travel times derived from contaminant breakthrough curves at individual sensor locations throughout the 2D tank. However, discrepancies between measured and simulated trace organic chemical concentrations (i.e., carbamazepine, sulfamethoxazole, tris (2-chloroethyl) phosphate, trimethoprim) were observed. While the FEFLOW simulation of breakthrough curves captured overall shapes of trace organic chemical concentrations well, the model struggled with matching individual data points, although compound-specific attenuation parameters were used. Interestingly, despite steady-state operation, oxidation-reduction potential measurements indicated temporal disturbances in hydraulic properties in the saturated zone of the 2D tank that affected water quality.
Semi-Smooth Newton Method for Solving 2D Contact Problems with Tresca and Coulomb Friction
Directory of Open Access Journals (Sweden)
Kristina Motyckova
2013-01-01
Full Text Available The contribution deals with contact problems for two elastic bodies with friction. After the description of the problem we present its discretization based on linear or bilinear finite elements. The semi--smooth Newton method is used to find the solution, from which we derive active sets algorithms. Finally, we arrive at the globally convergent dual implementation of the algorithms in terms of the Langrange multipliers for the Tresca problem. Numerical experiments conclude the paper.
Barre, Julien P G; Deletraz, Gaëlle; Frayret, Jérôme; Pinaly, Hervé; Donard, Olivier F X; Amouroux, David
2015-06-01
Geographically based investigations into atmospheric bio-monitoring usually provide information on concentration or occurrence data and spatial trends of specific contaminants over a specified study area. In this work, an original approach based on geographic information system (GIS) was used to establish metal contents (Hg, Cu, Pb, and Cd) in epiphytic lichens from 90 locations as atmospheric bio-monitors over a meso-scale area (Pyrénées-Atlantiques, southwestern France). This approach allows the integration of the heterogeneity of the territory and optimization of the sampling sites based on both socioeconomical and geophysical parameters (hereafter defined as urban, industrial, agricultural, and forested areas). The sampling strategy was first evaluated in several sites (n = 15) over different seasons and years in order to follow the temporal variability of the atmospheric metal input in lichens. The results demonstrate that concentration ranges remain constant over different sampling periods in "rural" areas (agricultural and forested). Higher variability is observed in the "anthropized" urban and industrial areas in relation to local atmospheric inputs. In this context, metal concentrations in lichens over the whole study show that (1) Hg and Cd are homogeneous over the whole territory (0.14 ± 0.04 and 0.38 ± 0.26 mg/kg, respectively), whereas (2) Cu and Pb are more concentrated in "anthropized" areas (9.3 and 11.9 mg/kg, respectively) than in "rural" ones (6.8 and 6.0 mg/kg, respectively) (Kruskall-Wallis, K(Cu) = 13.7 and K(Pb) = 9.7, p < 0.00001). They also showed a significant local enrichment for all metals in many locations in the Pays Basque (West) mainly due to metal and steel industrial activities. This confirms the local contribution of this contamination source over a wider geographic scale. A multiple linear regression model was applied to give an integrated spatialization of the data. This showed significant
HypGrid2D. A 2-d mesh generator
Energy Technology Data Exchange (ETDEWEB)
Soerensen, N.N.
1998-03-01
The implementation of a hyperbolic mesh generation procedure, based on an equation for orthogonality and an equation for the cell face area is described. The method is fast, robust and gives meshes with good smoothness and orthogonality. The procedure is implemented in a program called HypGrid2D. The HypGrid2D program is capable of generating C-, O- and `H`-meshes for use in connection with the EllipSys2D Navier-Stokes solver. To illustrate the capabilities of the program, some test examples are shown. First a series of C-meshes are generated around a NACA-0012 airfoil. Secondly a series of O-meshes are generated around a NACA-65-418 airfoil. Finally `H`-meshes are generated over a Gaussian hill and a linear escarpment. (au)
PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems
Neilson, David; Senatore, Gaetano
2009-05-01
This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas
Coulomb dissociation of N-20,N-21
Roeder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhaeuser, Roman; Goebel, Kathrin; Golubev, Pavel; Diaz, D. Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Bjorn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knoebel, Ronja; Kroell, Thorsten; Kruecken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; del Rio Saez, Jose Sanchez; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai
2016-01-01
Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N-20,N-21 are reported. Relativistic N-20,N-21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a
Coulomb dissociation of N-20,N-21
Roeder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhaeuser, Roman; Goebel, Kathrin; Golubev, Pavel; Diaz, D. Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Bjorn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knoebel, Ronja; Kroell, Thorsten; Kruecken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; del Rio Saez, Jose Sanchez; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai
2016-01-01
Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N-20,N-21 are reported. Relativistic N-20,N-21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a
Coulomb Effects in Few-Body Reactions
Directory of Open Access Journals (Sweden)
Deltuva A.
2010-04-01
Full Text Available The method of screening and renormalization is used to include the Coulomb interaction between the charged particles in the momentum-space description of three- and four-body nuclear reactions. The necessity for the renormalization of the scattering amplitudes and the reliability of the method is demonstrated. The Coulomb eﬀect on observables is discussed.
Ahmed, Zeeshan
2010-01-01
Designing and developing quality based computer game is always a challenging task for developers. In this paper I briefly discuss aero fighting war game based on simple 2D gaming concepts and developed in C & C++ programming languages, using old bitmapping concepts. Going into the details of the game development, I discuss the designed strategies, flow of game and implemented prototype version of game, especially for beginners of game programming.
The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.
Francisco, E.; And Others
1988-01-01
Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)
Coulomb string tension, asymptotic string tension, and the gluon chain
Greensite, Jeff; Szczepaniak, Adam P.
2015-02-01
We compute, via numerical simulations, the nonperturbative Coulomb potential of pure SU(3) gauge theory in Coulomb gauge. We find that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.
Fallow), Stray
2009-01-01
Having trouble with geometry? Do Pi, The Pythagorean Theorem, and angle calculations just make your head spin? Relax. With Head First 2D Geometry, you'll master everything from triangles, quads and polygons to the time-saving secrets of similar and congruent angles -- and it'll be quick, painless, and fun. Through entertaining stories and practical examples from the world around you, this book takes you beyond boring problems. You'll actually use what you learn to make real-life decisions, like using angles and parallel lines to crack a mysterious CSI case. Put geometry to work for you, and
Computational 2D Materials Database
DEFF Research Database (Denmark)
Rasmussen, Filip Anselm; Thygesen, Kristian Sommer
2015-01-01
We present a comprehensive first-principles study of the electronic structure of 51 semiconducting monolayer transition-metal dichalcogenides and -oxides in the 2H and 1T hexagonal phases. The quasiparticle (QP) band structures with spin-orbit coupling are calculated in the G(0)W(0) approximation...... and used as input to a 2D hydrogenic model to estimate exciton binding energies. Throughout the paper we focus on trends and correlations in the electronic structure rather than detailed analysis of specific materials. All the computed data is available in an open database....
Institute of Scientific and Technical Information of China (English)
杜修力; 金浏
2012-01-01
Concrete was assumed to compose of aggregate particles and a mortar matrix, and the concrete unit was processed equivalently based on the Voigt parallel model in the paper. The distribution of equivalent elastic modulus of a meso-unit was studied, based on the Weibull distribution, and a graphical method and the stepwise regression were applied to optimizing the estimated parameters. Furthermore, the validity of the assumed distribution was examined by the Kolmogorov test. The statistical parameter of element Young's modulus with different element-scale, and the spatial distribution randomness of aggregate were studied in the paper. The problem on material characteristic element scale of concrete of different grade-level was analyzed at the end of the paper. The analytical results indicate that: l) the form and the parameters of random distribution of elastic modulus of a concrete meso-scale unit have size effects, and not fully obey the Weibull distribution. 2) the variability of elastic modulus of a concrete meso-element associates with scales; and the variability increases firstly and tends to be stable gradually with the decrease of element size, which reflects the facts that there exists a reasonable representation of non-uniform degree of concrete at meso level. The reasonable scale, i.e. the variation coefficients tending to the inflection point of a smooth transition to the corresponding scale, is defined as a characteristic element scale. 3) The characteristic element scale of concrete material on two-grade, three-grade and four-grade are 10mm, 15mm and 18mm, respectively. 4) The spatial distribution randomness of aggregate has little effects on random distribution properties of elastic modulus of a concrete meso-unit.%假定混凝土是由骨料颗粒及砂浆基质组成的复合材料,基于Voigt并联模型对混凝土细观单元进行等效化,对单元的等效弹性模量进行统计分析。以Weibull分布为假设分布,
临沂地区一次冰雹过程的中尺度特征分析%Analysis on the Meso-scale Characteristics of a Hail Process in Linyi Area
Institute of Scientific and Technical Information of China (English)
刘英杰; 曹兴锋; 朱义青; 王庆华; 李炳文
2011-01-01
[目的]研究临沂地区一次冰雹过程的中尺度特征.[方法]综合利用MICAPS常规观测数据、地面加密自动站、MM5模式产品及多普勒天气雷达资料等观测资料,分析了2010年5月30日发生在山东半岛及鲁东南地区的一次强对流冰雹天气过程,探讨此次强对流天气发生的环流背景、物理机制以及中小尺度系统特征,并从中找出一些这类天气发生、发展的规律.[结果]此次强对流天气主要是受冷涡横槽的影响；高空西北气流、低空西南气流以及高空干冷、低层暖湿,加上前倾槽的配置,从而产生强对流天气.雷达回波分析表明,此次过程雷达回波属于典型的多单体风暴回波,强回波区位于回波最前沿,对流发展最剧烈时回波强度达65 dBz,回波顶高超过11km,且伴随风暴单体的发展,不断有垂直液态水含量产品大值区跳跃性生消,并存在明显的弱回波区；风暴单体随着降水系统向东南方向移动,在单体移动方向的右前侧表现出钩状回波特征.分析冰雹天气发生前后不同仰角上径向速度场的演变特征发现,径向速度场在冰雹天气发生前有一些预兆性的变化.用多普勒雷达产品改进MM5模式的初始场,可以一定程度上改善预报效果,提高短时、临近预报的准确度.[结论]该研究为今后强对流天气的短时、临近预报工作积累了经验.%[Objective]The research aimed to study the meso-scale characteristics of a hail process in linyi area. [ Method ] By comprehen sively using MICAPS conventional observation data, ground encryption automatic station, MM5 model product and Doppler weather radar data, a strong convective hail weather process which happened in Shandong Peninsula and southeast of Shandong on May 30, 2010 was analyzed. The circulation background and physical mechanism of strong convection weather occurrence, the features of meso-and micro-scale systems were discussed. Some
Smooth models for the Coulomb potential
González-Espinoza, Cristina E; Karwowski, Jacek; Savin, Andreas
2016-01-01
Smooth model potentials with parameters selected to reproduce the spectrum of one-electron atoms are used to approximate the singular Coulomb potential. Even when the potentials do not mimic the Coulomb singularity, much of the spectrum is reproduced within the chemical accuracy. For the Hydrogen atom, the smooth approximations to the Coulomb potential are more accurate for higher angular momentum states. The transferability of the model potentials from an attractive interaction (Hydrogen atom) to a repulsive one (Harmonium and the uniform electron gas) is discussed.
Directory of Open Access Journals (Sweden)
Mohanan Geetha Gopisankar
2017-10-01
Full Text Available Cytochromes are proteins that catalyze electron transfer reactions of many metabolic pathways. They are involved in drug metabolism and thus determines the therapeutic safety and efficacy of drugs in patients. Cytochrome P450 in mitochondria accounts for 90% of the oxidative metabolism of clinically used drugs during phase 1 reaction. CYP2D6 is a major gene member of this superfamily as it carries out metabolism of 25% of drugs currently available in the market. Contrary to the concept of specificity of enzyme action these can metabolize substrates of different chemistry. Since its discovery, many have intensively studied this unique hemoprotein and contributed to the elucidation of its molecular properties and physiological functions and also the structure-activity relationships of its substrates and inhibitors. Its activity ranges considerably within a population due to genetic polymorphisms which lead to varied responses to drug intake. Studying such polymorphisms which cause a significant impact in the management of patients and helps to achieve the final target of personalizing medicine. This review briefs about history, structure, and function, molecular genetics, substrates, regulators and inhibitors of CYP2D6 and its clinical pharmacogenomics.
Coulomb screening in linear coasting nucleosynthesis
Singh, Parminder
2015-01-01
We investigate the impact of coulomb screening on primordial nucleosynthesis in a universe having scale factor that evolves linearly with time. Coulomb screening affects primordial nucleosynthesis via enhancement of thermonuclear reaction rates. This enhancement is determined by the solving Poisson equation within the context of mean field theory (under appropriate conditions during the primordial nucleosynthesis). Using these results, we claim that the mean field estimates of coulomb screening hardly affect the predicted element abundances and nucleosynthesis parameters$, \\{\\eta_9,\\xi_e\\}$. The deviations from mean field estimates are also studied in detail by boosting genuine screening results with the screening parameter ($\\omega_s$). These deviations show negligible effect on the element abundances and on nucleosynthesis parameters. This work thus rules out the coulomb screening effects on primordial nucleosynthesis in slow evolving models and confirms that constraints in ref.[7] on nucleosynthesis parame...
Comments on Coulomb pairing in aromatic hydrocarbons
Huber, D L
2013-01-01
Recently reported anomalies in the double-photonionization spectra of aromatic molecules such as benzene, naphthalene, anthracene and coronene are attributed to Coulomb-pair resonances of pi electrons.
Cavity QED experiments with ion Coulomb crystals
DEFF Research Database (Denmark)
Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan
2009-01-01
Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....
Coulomb Distortion in the Inelastic Regime
Energy Technology Data Exchange (ETDEWEB)
Patricia Solvignon, Dave Gaskell, John Arrington
2009-09-01
The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$.
Cavity QED experiments with ion Coulomb crystals
DEFF Research Database (Denmark)
Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan
2009-01-01
Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained.......Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....
Gaussian expansion approach to Coulomb breakup
Egami, T; Matsumoto, T; Iseri, Y; Kamimura, M; Yahiro, M
2004-01-01
An accurate treatment of Coulomb breakup reactions is presented by using both the Gaussian expansion method and the method of continuum discretized coupled channels. As $L^2$-type basis functions for describing Coulomb breakup processes, we take complex-range Gaussian functions, which form in good approximation a complete set in a large configuration space being important for the processes. Accuracy of the method is tested quantitatively for $^{8}{\\rm B}+^{58}$Ni scattering at 25.8 MeV.
Waldin, Nicholas
2016-06-24
2D color maps are often used to visually encode complex data characteristics such as heat or height. The comprehension of color maps in visualization is affected by the display (e.g., a monitor) and the perceptual abilities of the viewer. In this paper we present a novel method to measure a user\\'s ability to distinguish colors of a two-dimensional color map on a given monitor. We show how to adapt the color map to the user and display to optimally compensate for the measured deficiencies. Furthermore, we improve user acceptance of the calibration procedure by transforming the calibration into a game. The user has to sort colors along a line in a 3D color space in a competitive fashion. The errors the user makes in sorting these lines are used to adapt the color map to his perceptual capabilities.
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
A novel pilot stage valve called simplified 2D valve, which utilizes both rotary and linear motions of a single spool, is presented.The rotary motion of the spool incorporating hydraulic resistance bridge, formed by a damper groove and a crescent overlap opening, is utilized as pilot to actuate linear motion of the spool.A criterion for stability is derived from the linear analysis of the valve.Special experiments are designed to acquire the mechanical stiffness, the pilot leakage and the step response.It is shown that the sectional size of the spiral groove affects the dynamic response and the stiffness contradictorily and is also very sensitive to the pilot leakage.Therefore, it is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters.Nevertheless, it is possible to sustain the dynamic response at a fairly high level, while keeping the leakage of the pilot stage at an acceptable level.
Quantum coherence selective 2D Raman-2D electronic spectroscopy.
Spencer, Austin P; Hutson, William O; Harel, Elad
2017-03-10
Electronic and vibrational correlations report on the dynamics and structure of molecular species, yet revealing these correlations experimentally has proved extremely challenging. Here, we demonstrate a method that probes correlations between states within the vibrational and electronic manifold with quantum coherence selectivity. Specifically, we measure a fully coherent four-dimensional spectrum which simultaneously encodes vibrational-vibrational, electronic-vibrational and electronic-electronic interactions. By combining near-impulsive resonant and non-resonant excitation, the desired fifth-order signal of a complex organic molecule in solution is measured free of unwanted lower-order contamination. A critical feature of this method is electronic and vibrational frequency resolution, enabling isolation and assignment of individual quantum coherence pathways. The vibronic structure of the system is then revealed within an otherwise broad and featureless 2D electronic spectrum. This method is suited for studying elusive quantum effects in which electronic transitions strongly couple to phonons and vibrations, such as energy transfer in photosynthetic pigment-protein complexes.
Two dimensional graphene nanogenerator by coulomb dragging: Moving van der Waals heterostructure
Energy Technology Data Exchange (ETDEWEB)
Zhong, Huikai; Li, Xiaoqiang; Wu, Zhiqian; Zhang, Shengjiao; Xu, Zhijuan [Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China); Chen, Hongsheng; Lin, Shisheng, E-mail: shishenglin@zju.edu.cn [Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China); State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027 (China)
2015-06-15
Harvesting energy from environment is the current focus of scientific community. Here, we demonstrate a graphene nanogenerator, which is based on moving van der Waals heterostructure formed between graphene and two dimensional (2D) graphene oxide (GO). This nanogenerator can convert mechanical energy into electricity with a voltage output of around 10 mV. Systematic experiments reveal the generated electricity originates from the coulomb interaction induced momentum transfer between 2D GO and holes in graphene. 2D boron nitride was also demonstrated to be effective in the framework of moving van der Waals heterostructure nanogenerator. This investigation of nanogenerator based on the interaction between 2D macromolecule materials will be important to understand the origin of the flow-induced potential in nanomaterials and may have great potential in practical applications.
Two dimensional graphene nanogenerator by coulomb dragging: Moving van der Waals heterostructure
Zhong, Huikai; Li, Xiaoqiang; Wu, Zhiqian; Zhang, Shengjiao; Xu, Zhijuan; Chen, Hongsheng; Lin, Shisheng
2015-06-01
Harvesting energy from environment is the current focus of scientific community. Here, we demonstrate a graphene nanogenerator, which is based on moving van der Waals heterostructure formed between graphene and two dimensional (2D) graphene oxide (GO). This nanogenerator can convert mechanical energy into electricity with a voltage output of around 10 mV. Systematic experiments reveal the generated electricity originates from the coulomb interaction induced momentum transfer between 2D GO and holes in graphene. 2D boron nitride was also demonstrated to be effective in the framework of moving van der Waals heterostructure nanogenerator. This investigation of nanogenerator based on the interaction between 2D macromolecule materials will be important to understand the origin of the flow-induced potential in nanomaterials and may have great potential in practical applications.
Hakobyan, Tigran
2015-01-01
We define the integrable N-dimensional Calogero-Coulomb-Stark and two-center Calogero-Coulomb systems and construct their constants of motion via the Dunkl operators. Their Schroedinger equations decouple in parabolic and elliptic coordinates, respectively, into the set of three differential equations like for the Coulomb-Stark and two-center Coulomb problems.
2D transition metal dichalcogenides
Manzeli, Sajedeh; Ovchinnikov, Dmitry; Pasquier, Diego; Yazyev, Oleg V.; Kis, Andras
2017-08-01
Graphene is very popular because of its many fascinating properties, but its lack of an electronic bandgap has stimulated the search for 2D materials with semiconducting character. Transition metal dichalcogenides (TMDCs), which are semiconductors of the type MX2, where M is a transition metal atom (such as Mo or W) and X is a chalcogen atom (such as S, Se or Te), provide a promising alternative. Because of its robustness, MoS2 is the most studied material in this family. TMDCs exhibit a unique combination of atomic-scale thickness, direct bandgap, strong spin-orbit coupling and favourable electronic and mechanical properties, which make them interesting for fundamental studies and for applications in high-end electronics, spintronics, optoelectronics, energy harvesting, flexible electronics, DNA sequencing and personalized medicine. In this Review, the methods used to synthesize TMDCs are examined and their properties are discussed, with particular attention to their charge density wave, superconductive and topological phases. The use of TMCDs in nanoelectronic devices is also explored, along with strategies to improve charge carrier mobility, high frequency operation and the use of strain engineering to tailor their properties.
Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals.
Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko
2007-04-14
The authors propose a new linear-scaling method for the fast evaluation of Coulomb integrals with Gaussian basis functions called the Gaussian and finite-element Coulomb (GFC) method. In this method, the Coulomb potential is expanded in a basis of mixed Gaussian and finite-element auxiliary functions that express the core and smooth Coulomb potentials, respectively. Coulomb integrals can be evaluated by three-center one-electron overlap integrals among two Gaussian basis functions and one mixed auxiliary function. Thus, the computational cost and scaling for large molecules are drastically reduced. Several applications to molecular systems show that the GFC method is more efficient than the analytical integration approach that requires four-center two-electron repulsion integrals. The GFC method realizes a near linear scaling for both one-dimensional alanine alpha-helix chains and three-dimensional diamond pieces.
Learn Unity for 2D game development
Thorn, Alan
2013-01-01
The only Unity book specifically covering 2D game development Written by Alan Thorn, experience game developer and author of seven books on game programming Hands-on examples of all major aspects of 2D game development using Unity
Coulomb screening in graphene with topological defects
Chakraborty, Baishali; Gupta, Kumar S.; Sen, Siddhartha
2015-06-01
We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb impurity. The period of variation depends on the conical defect. In the presence of the conical defect, the Fano resonances begin to appear in the transport cross-section for a lower value of the Coulomb charge. For both sub and supercritical regime we derive the dependence of LDOS on the conical defect. The effects of generalized boundary condition on the physical observables are also discussed.
Electron-Phonon Scattering in Atomically Thin 2D Perovskites.
Guo, Zhi; Wu, Xiaoxi; Zhu, Tong; Zhu, Xiaoyang; Huang, Libai
2016-11-22
Two-dimensional (2D) atomically thin perovskites with strongly bound excitons are highly promising for optoelectronic applications. However, the nature of nonradiative processes that limit the photoluminescence (PL) efficiency remains elusive. Here, we present time-resolved and temperature-dependent PL studies to systematically address the intrinsic exciton relaxation pathways in layered (C4H9NH3)2(CH3NH3)n-1PbnI3n+1 (n = 1, 2, 3) structures. Our results show that scatterings via deformation potential by acoustic and homopolar optical phonons are the main scattering mechanisms for excitons in ultrathin single exfoliated flakes, exhibiting a T(γ) (γ = 1.3 to 1.9) temperature dependence for scattering rates. We attribute the absence of polar optical phonon and defect scattering to efficient screening of Coulomb potential, similar to what has been observed in 3D perovskites. These results establish an understanding of the origins of nonradiative pathways and provide guidelines for optimizing PL efficiencies of atomically thin 2D perovskites.
Observation of ionic Coulomb blockade in nanopores
Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; di Ventra, Massimiliano; Radenovic, Aleksandra
2016-08-01
Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels.
Leading order QCD in Coulomb gauge
Watson, Peter
2011-01-01
Coulomb gauge QCD in the first order formalism can be written in terms of a ghost-free, nonlocal action that ensures total color charge conservation via Gauss' law. Making an Ansatz whereby the nonlocal term (the Coulomb kernel) is replaced by its expectation value, the resulting Dyson-Schwinger equations can be derived. With a leading order truncation, these equations reduce to the gap equations for the static gluon and quark propagators obtained from a quasi-particle approximation to the canonical Hamiltonian approach. Moreover a connection to the heavy quark limit can be established, allowing an intuitive explanation for the charge constraint and infrared divergences.
Coulomb drag in coherent mesoscopic systems
DEFF Research Database (Denmark)
Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2001-01-01
We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means, such as th......We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means...
González, A. Ojeda; Prestes, A.; Laurindo Sousa, A. Nilson
2016-08-01
We discuss the relationship between the Coulomb gauge, the existence of an invariant axis, and the dimensionality (2-D or 2frac {1}{2}-D) of the magnetic field in a mathematical-physical formalism that leads us to the Grad-Shafranov (GS) equation. In the literature, we found that a 2-D magnetic structure is used as a prerequisite to derive the GS equation from the Vlasov equation. However, other consulted works are based on a 2frac {1}{2}-D (two-and-a-half) magnetic structure as a prerequisite to derive the GS equation from the balance of forces between the pressure gradient and the magnetic force, respectively. We replaced the magnetic vector potential on Ampère's equation and used the Coulomb gauge to obtain a system of three Poisson equations, one for each component. We also used the same procedure explained above, but without the Coulomb gauge. Comparing z-component in both equation systems, we concluded that there are two possible solutions. We suggest using a 2frac {1}{2}-D magnetic field configuration instead of a 2-D, when working with kinetic theory or magnetostatic equilibrium to derive the GS equation. We clarified that there is no relationship between the Coulomb gauge and the magnetic field dimensionality. In this problem, the invariant axis condition is imposed, which means that ěc {nabla }\\cdot ěc {A} is independent of z, i.e., ěc {nabla }\\cdot ěc {A} could have any value in which an invariant axis is a sufficient condition to obtain the GS equation.
A Coulomb-Like Off-Shell T-Matrix with the Correct Coulomb Phase Shift
Oryu, Shinsho; Watanabe, Takashi; Hiratsuka, Yasuhisa; Togawa, Yoshio
2017-03-01
We confirm the reliability of the well-known Coulomb renormalization method (CRM). It is found that the CRM is only available for a very-long-range screened Coulomb potential (SCP). However, such an SCP calculation in momentum space is considerably difficult because of the cancelation of significant digits. In contrast to the CRM, we propose a new method by using an on-shell equivalent SCP and the rest term. The two-potential theory with r-space is introduced, which defines fully the off-shell Coulomb amplitude.
Interatomic Coulombic decay in helium nanodroplets
DEFF Research Database (Denmark)
Shcherbinin, Mykola; Laforge, Aaron; Sharma, Vandana
2017-01-01
Interatomic Coulombic decay (ICD) is induced in helium nanodroplets by photoexciting the n=2 excited state of He+ using XUV synchrotron radiation. By recording multiple-coincidence electron and ion images we find that ICD occurs in various locations at the droplet surface, inside the surface region...
Coulomb drag between helical Luttinger liquids
Kainaris, N.; Gornyi, I. V.; Levchenko, A.; Polyakov, D. G.
2017-01-01
We theoretically study Coulomb drag between two helical edges with broken spin-rotational symmetry, such as would occur in two capacitively coupled quantum spin Hall insulators. For the helical edges, Coulomb drag is particularly interesting because it specifically probes the inelastic interactions that break the conductance quantization for a single edge. Using the kinetic equation formalism, supplemented by bosonization, we find that the drag resistivity ρD exhibits a nonmonotonic dependence on the temperature T . In the limit of low T ,ρD vanishes with decreasing T as a power law if intraedge interactions are not too strong. This is in stark contrast to Coulomb drag in conventional quantum wires, where ρD diverges at T →0 irrespective of the strength of repulsive interactions. Another unusual property of Coulomb drag between the helical edges concerns higher T for which, unlike in the Luttinger liquid model, drag is mediated by plasmons. The special type of plasmon-mediated drag can be viewed as a distinguishing feature of the helical liquid—because it requires peculiar umklapp scattering only available in the presence of a Dirac point in the electron spectrum.
Coulomb Logarithm, Version 1.0
Energy Technology Data Exchange (ETDEWEB)
2016-11-23
Clog is a library of charged particle stopping powers and related Coulomb logarithm processes in a plasma. The stopping power is a particularly useful quantity for plasma physics, as it measures the energy loss of per unit length of charged particle as it traverses a plasma. Clog's primary stopping power is the BPS (Brown-Preston-Singleton) theory.
Coulomb's Electrical Measurements. Experiment No. 14.
Devons, Samuel
Presented is information related to the life and work of Charles Coulomb as well as detailed notes of his measurements of the distribution of electricity on conductors. The two methods that he used (the large torsion balance, and the timing of "force" oscillations) are described. (SA)
Perspectives for spintronics in 2D materials
Directory of Open Access Journals (Sweden)
Wei Han
2016-03-01
Full Text Available The past decade has been especially creative for spintronics since the (rediscovery of various two dimensional (2D materials. Due to the unusual physical characteristics, 2D materials have provided new platforms to probe the spin interaction with other degrees of freedom for electrons, as well as to be used for novel spintronics applications. This review briefly presents the most important recent and ongoing research for spintronics in 2D materials.
Hamzavi, Majid
2012-01-01
The exact Dirac equation for the energy-dependent Coulomb (EDC) potential including a Coulomb-like tensor (CLT) potential has been studied in the presence of spin and pseudospin (p-spin) symmetries with arbitrary spin-orbit quantum number The energy eigenvalues and corresponding eigenfunctions are obtained in the framework of asymptotic iteration method (AIM). Some numerical results are obtained in the presence and absence of EDC and CLT potentials.
Bedform characterization through 2D spectral analysis
DEFF Research Database (Denmark)
Lefebvre, Alice; Ernstsen, Verner Brandbyge; Winter, Christian
2011-01-01
characteristics using twodimensional (2D) spectral analysis is presented and tested on seabed elevation data from the Knudedyb tidal inlet in the Danish Wadden Sea, where large compound bedforms are found. The bathymetric data were divided into 20x20 m areas on which a 2D spectral analysis was applied. The most...... energetic peak of the 2D spectrum was found and its energy, frequency and direction were calculated. A power-law was fitted to the average of slices taken through the 2D spectrum; its slope and y-intercept were calculated. Using these results the test area was morphologically classified into 4 distinct...
Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots
Keller, A. J.; Lim, J. S.; Sánchez, David; López, Rosa; Amasha, S.; Katine, J. A.; Shtrikman, Hadas; Goldhaber-Gordon, D.
2016-08-01
In Coulomb drag, a current flowing in one conductor can induce a voltage across an adjacent conductor via the Coulomb interaction. The mechanisms yielding drag effects are not always understood, even though drag effects are sufficiently general to be seen in many low-dimensional systems. In this Letter, we observe Coulomb drag in a Coulomb-coupled double quantum dot and, through both experimental and theoretical arguments, identify cotunneling as essential to obtaining a correct qualitative understanding of the drag behavior.
Sensor Craft Control Using Drone Craft with Coulomb Propulsion System
Joe, Hyunsik
2005-01-01
The Coulomb propulsion system has no exhaust plume impingement problem with neighboring spacecraft and does not contaminate their sensors because it requires essentially no propellant. It is suitable to close formation control on the order of dozens of meters. The Coulomb forces are internal forces of the formation and they influence all charged spacecraft at the same time. Highly nonlinear and strongly coupled equations of motion of Coulomb formation makes creating a Coulomb control method a...
Nonlocal Coulomb interaction in the two-dimensional spin-1/2 Falicov–Kimball model
Indian Academy of Sciences (India)
S K Bhowmick; N K Ghosh
2012-02-01
The two-dimensional (2D) extended Falicov–Kimball model has been studied to observe the role of nonlocal Coulomb interaction (nc) using an exact diagonalization technique. The f-state occupation ($n^f$), the f–d intersite correlation function (fd), the speciﬁc heat (), entropy () and the speciﬁc heat coefﬁcient () have been examined. Nonlocal Coulomb interaction-induced discontinuous insulator-to-metal transition occurs at a critical f-level energy. More ordered state is obtained with the increase of nc. In the speciﬁc heat curves, two-peak structure as well as a singlepeak structure appears. At low-temperature region, a sharp rise in the speciﬁc heat coefﬁcient is observed. The peak value of shifts to the higher temperature region with nc.
Annotated Bibliography of EDGE2D Use
Energy Technology Data Exchange (ETDEWEB)
J.D. Strachan and G. Corrigan
2005-06-24
This annotated bibliography is intended to help EDGE2D users, and particularly new users, find existing published literature that has used EDGE2D. Our idea is that a person can find existing studies which may relate to his intended use, as well as gain ideas about other possible applications by scanning the attached tables.
DEFF Research Database (Denmark)
Burcharth, Hans F.; Andersen, Thomas Lykke; Jensen, Palle Meinert
This report present the results of 2D physical model tests (length scale 1:50) carried out in a waveflume at Dept. of Civil Engineering, Aalborg University (AAU).......This report present the results of 2D physical model tests (length scale 1:50) carried out in a waveflume at Dept. of Civil Engineering, Aalborg University (AAU)....
Structural Theory of 2-d Adinkras
Iga, Kevin
2015-01-01
Adinkras are combinatorial objects developed to study 1-dimensional supersymmetry representations. Recently, 2-d Adinkras have been developed to study 2-dimensional supersymmetry. In this paper, we classify all 2-d Adinkras, confirming a conjecture of T. H\\"ubsch. Along the way, we obtain other structural results, including a simple characterization of H\\"ubsch's even-split doubly even code.
Coulomb crystallization of highly charged ions.
Schmöger, L; Versolato, O O; Schwarz, M; Kohnen, M; Windberger, A; Piest, B; Feuchtenbeiner, S; Pedregosa-Gutierrez, J; Leopold, T; Micke, P; Hansen, A K; Baumann, T M; Drewsen, M; Ullrich, J; Schmidt, P O; López-Urrutia, J R Crespo
2015-03-13
Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.
Photodetachment Microscope with Repulsive Coulomb Field
Golovinski, P A
2011-01-01
Investigation of electronic waves with high coherence in photodetachment of a negative ion gives a physical basis to develop the holographic electronic microscopy with high resolution. The interference pattern is considered in the framework of steady-state wave approach. In semiclassical approximation, an outgoing wave is described by the amplitude slowly varying along a trajectory. Quantum description of electron photodetachment from negative ion is formulated with the help of the inhomogeneous Schr\\"odinger equation. Its asymptotic solution is expressed in terms of the Green function that has exact expression for the homogeneous electric field and the Coulomb field. It is demonstrated that repulsive Coulomb field is effective for magnification of the interference pattern at a short distance from an ion. For the first time, as shown for this case, the interference pattern in asymptotic area can be calculated by means of global semiclassical approximation or, a little more roughly, by simple uniform field app...
Non-linear conductivity in Coulomb glasses
Energy Technology Data Exchange (ETDEWEB)
Voje, A.; Bergli, J. [Department of Physics, University of Oslo, P. O. Box 1048 Blindern, 0316 Oslo (Norway); Ortuno, M.; Somoza, A.M. [Departamento de Fisica - CIOyN, Universidad de Murcia, Murcia 30.071 (Spain); Caravaca, M.
2009-12-15
We have studied the nonlinear conductivity of two-dimensional Coulomb glasses. We have used a Monte Carlo algorithm to simulate the dynamic of the system under an applied electric field E. We have compared results for two different models: a regular square lattice with only diagonal disorder and a random array of sites with diagonal and off-diagonal disorder. We have found that for moderate fields the logarithm of the conductivity is proportional to {radical}(E)/T{sup 2}, reproducing experimental results. We have also found that in the nonlinear regime the site occupancy in the Coulomb gap follows a Fermi-Dirac distribution with an effective temperature T{sub eff} higher than the phonon bath temperature T. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
Frictional Coulomb drag in strong magnetic fields
DEFF Research Database (Denmark)
Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang;
1997-01-01
A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21) is eval......A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21......) is evaluated using diagrammatic techniques. The transresistivity is given by an integral over energy and momentum transfer weighted by the product of the screened interlayer interaction and the phase space for scattering events. We demonstrate, by a numerical analysis of the transresistivity, that for well...
Coulomb dissociation of $^{20,21}$N
Röder, Marko; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J G; Burgunder, G; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A; Farinon, F; Fraile, Luis M; Freer, Martin; Freudenberger, M; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Diaz, Diego Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Bleis, Tudi Le; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Caro, Magdalena Mostazo; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S; Plag, Ralf; Prochazka, A; Rahaman, Md Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Saez, Jose Sanchez del Rio; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G; Wimmer, Christine; Winfield, J S; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai
2016-01-01
Neutron-rich light nuclei and their reactions play an important role for the creation of chemical elements. Here, data from a Coulomb dissociation experiment on $^{20,21}$N are reported. Relativistic $^{20,21}$N ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ and $^{20}\\mathrm{N}(\\mathrm{n},\\gamma)^{21}\\mathrm{N}$ excitation functions and thermonuclear reaction rates have been determined. The $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ rate is up to a factor of 5 higher at $T<1$\\,GK with respect to previous theoretical calculations, leading to a 10\\,\\% decrease in the predicted fluorine abundance.
Module of System Galactica with Coulomb's Interaction
Directory of Open Access Journals (Sweden)
Joseph J. Smulsky
2014-12-01
Full Text Available The system Galactica of free access is supplemented module for the Coulomb interaction. It is based on a high-precision method for solving differential equations of motion of N charged particles. The paper presents all the theoretical and practical issues required to use this module of system Galactica so that even the beginning researcher could study the motion of particles, atoms and molecules.
Coulomb collision effects on linear Landau damping
Energy Technology Data Exchange (ETDEWEB)
Callen, J. D., E-mail: callen@engr.wisc.edu [University of Wisconsin, Madison, Wisconsin 53706-1609 (United States)
2014-05-15
Coulomb collisions at rate ν produce slightly probabilistic rather than fully deterministic charged particle trajectories in weakly collisional plasmas. Their diffusive velocity scattering effects on the response to a wave yield an effective collision rate ν{sub eff} ≫ ν and a narrow dissipative boundary layer for particles with velocities near the wave phase velocity. These dissipative effects produce temporal irreversibility for times t ≳ 1/ν{sub eff} during Landau damping of a small amplitude Langmuir wave.
Coulomb dissociation studies for astrophysical thermonuclear reactions
Energy Technology Data Exchange (ETDEWEB)
Motobayashi, T. [Dept. of Physics, Rikkyo Univ., Toshima, Tokyo (Japan)
1998-06-01
The Coulomb dissociation method was applied to several radiative capture processes of astrophysical interest. The method has an advantage of high experimental efficiency, which allow measurements with radioactive nuclear beams. The reactions {sup 13}N(p,{gamma}){sup 14}O and {sup 7}Be(p,{gamma}){sup 8}B are mainly discussed. They are the key reaction in the hot CNO cycle in massive stars and the one closely related to the solar neutrino problem, respectively. (orig.)
Elastic Coulomb breakup of $^{34}$Na
Singh, G; Chatterjee, R
2016-01-01
Purpose : The aim of this paper is to study the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb to give us a core of $^{33}$Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of $^{34}$Na. Method : A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb at 100 MeV/u. The triple differential cross-section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum and angular distributions as well as the average momenta, along with the energy-angular distributions. Results : The total one neutron removal cross-section is calculated to test the possible ground state configurations of $^{34}$Na. The average momentum results along with energy-angular calculations indicate $^{34}$Na to ha...
2D materials for nanophotonic devices
Xu, Renjing; Yang, Jiong; Zhang, Shuang; Pei, Jiajie; Lu, Yuerui
2015-12-01
Two-dimensional (2D) materials have become very important building blocks for electronic, photonic, and phononic devices. The 2D material family has four key members, including the metallic graphene, transition metal dichalcogenide (TMD) layered semiconductors, semiconducting black phosphorous, and the insulating h-BN. Owing to the strong quantum confinements and defect-free surfaces, these atomically thin layers have offered us perfect platforms to investigate the interactions among photons, electrons and phonons. The unique interactions in these 2D materials are very important for both scientific research and application engineering. In this talk, I would like to briefly summarize and highlight the key findings, opportunities and challenges in this field. Next, I will introduce/highlight our recent achievements. We demonstrated atomically thin micro-lens and gratings using 2D MoS2, which is the thinnest optical component around the world. These devices are based on our discovery that the elastic light-matter interactions in highindex 2D materials is very strong. Also, I would like to introduce a new two-dimensional material phosphorene. Phosphorene has strongly anisotropic optical response, which creates 1D excitons in a 2D system. The strong confinement in phosphorene also enables the ultra-high trion (charged exciton) binding energies, which have been successfully measured in our experiments. Finally, I will briefly talk about the potential applications of 2D materials in energy harvesting.
Hybridized Plasmons in 2D Nanoslits: From Graphene to Anisotropic 2D Materials
DEFF Research Database (Denmark)
Gonçalves, P. A. D.; Xiao, Sanshui; Peres, N. M. R.
2017-01-01
of arbitrary width, and remains valid irrespective of the 2D conductive material (e.g., doped graphene, 2D transition metal dichalcogenides, or phosphorene). We derive the dispersion relation of the hybrid modes of a 2D nanoslit along with the corresponding induced potential and electric field distributions...
DEFF Research Database (Denmark)
Clausen, Johan; Andersen, Lars; Damkilde, Lars
2010-01-01
This paper compares calculation results obtained with the Mohr-Coulomb and Drucker-Prager material models. The models are implemented in a finite element code and the exact models are used, i.e. no rounding of yield surface corners or apices is performed. Results for both 2D and 3D calculations...
Papp, Z
1996-01-01
We demonstrate the feasibility and efficiency of the Coulomb-Sturmian separable expansion method for generating accurate solutions of the Faddeev equations. Results obtained with this method are reported for several benchmark cases of bosonic and fermionic three-body systems. Correct bound-state results in agreement with the ones established in the literature are achieved for short-range interactions. We outline the formalism for the treatment of three-body Coulomb systems and present a bound-state calculation for a three-boson system interacting via Coulomb plus short-range forces. The corresponding result is in good agreement with the answer from a recent stochastic-variational-method calculation.
Dekker, T.; de Zwart, S. T.; Willemsen, O. H.; Hiddink, M. G. H.; IJzerman, W. L.
2006-02-01
A prerequisite for a wide market acceptance of 3D displays is the ability to switch between 3D and full resolution 2D. In this paper we present a robust and cost effective concept for an auto-stereoscopic switchable 2D/3D display. The display is based on an LCD panel, equipped with switchable LC-filled lenticular lenses. We will discuss 3D image quality, with the focus on display uniformity. We show that slanting the lenticulars in combination with a good lens design can minimize non-uniformities in our 20" 2D/3D monitors. Furthermore, we introduce fractional viewing systems as a very robust concept to further improve uniformity in the case slanting the lenticulars and optimizing the lens design are not sufficient. We will discuss measurements and numerical simulations of the key optical characteristics of this display. Finally, we discuss 2D image quality, the switching characteristics and the residual lens effect.
Energy Technology Data Exchange (ETDEWEB)
Ginsparg, P.
1991-01-01
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
Energy Technology Data Exchange (ETDEWEB)
Ginsparg, P.
1991-12-31
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
2D Saturable Absorbers for Fibre Lasers
Directory of Open Access Journals (Sweden)
Robert I. Woodward
2015-11-01
Full Text Available Two-dimensional (2D nanomaterials are an emergent and promising platform for future photonic and optoelectronic applications. Here, we review recent progress demonstrating the application of 2D nanomaterials as versatile, wideband saturable absorbers for Q-switching and mode-locking fibre lasers. We focus specifically on the family of few-layer transition metal dichalcogenides, including MoS2, MoSe2 and WS2.
Image processing of 2D crystal images.
Arheit, Marcel; Castaño-Díez, Daniel; Thierry, Raphaël; Gipson, Bryant R; Zeng, Xiangyan; Stahlberg, Henning
2013-01-01
Electron crystallography of membrane proteins uses cryo-transmission electron microscopy to image frozen-hydrated 2D crystals. The processing of recorded images exploits the periodic arrangement of the structures in the images to extract the amplitudes and phases of diffraction spots in Fourier space. However, image imperfections require a crystal unbending procedure to be applied to the image before evaluation in Fourier space. We here describe the process of 2D crystal image unbending, using the 2dx software system.
Applications of 2D helical vortex dynamics
DEFF Research Database (Denmark)
Okulov, Valery; Sørensen, Jens Nørkær
2010-01-01
In the paper, we show how the assumption of helical symmetry in the context of 2D helical vortices can be exploited to analyse and to model various cases of rotating flows. From theory, examples of three basic applications of 2D dynamics of helical vortices embedded in flows with helical symmetry...... of the vorticity field are addressed. These included some of the problems related to vortex breakdown, instability of far wakes behind rotors and vortex theory of ideal rotors....
Yang, Li-Ming; Dornfeld, Matthew; Frauenheim, Thomas; Ganz, Eric
2015-10-21
We predict a highly stable and robust atomically thin gold monolayer with a hexagonal close packed lattice stabilized by metallic bonding with contributions from strong relativistic effects and aurophilic interactions. We have shown that the framework of the Au monolayer can survive 10 ps MD annealing simulations up to 1400 K. The framework is also able to survive large motions out of the plane. Due to the smaller number of bonds per atom in the 2D layer compared to the 3D bulk we observe significantly enhanced energy per bond (0.94 vs. 0.52 eV per bond). This is similar to the increase in bond strength going from 3D diamond to 2D graphene. It is a non-magnetic metal, and was found to be the global minima in the 2D space. Phonon dispersion calculations demonstrate high kinetic stability with no negative modes. This 2D gold monolayer corresponds to the top monolayer of the bulk Au(111) face-centered cubic lattice. The close-packed lattice maximizes the aurophilic interactions. We find that the electrons are completely delocalized in the plane and behave as 2D nearly free electron gas. We hope that the present work can inspire the experimental fabrication of novel free standing 2D metal systems.
2d index and surface operators
Gadde, Abhijit; Gukov, Sergei
2014-03-01
In this paper we compute the superconformal index of 2d (2, 2) supersymmetric gauge theories. The 2d superconformal index, a.k.a. flavored elliptic genus, is computed by a unitary matrix integral much like the matrix integral that computes the 4d superconformal index. We compute the 2d index explicitly for a number of examples. In the case of abelian gauge theories we see that the index is invariant under flop transition and under CY-LG correspondence. The index also provides a powerful check of the Seiberg-type duality for non-abelian gauge theories discovered by Hori and Tong. In the later half of the paper, we study half-BPS surface operators in = 2 super-conformal gauge theories. They are engineered by coupling the 2d (2, 2) supersymmetric gauge theory living on the support of the surface operator to the 4d = 2 theory, so that different realizations of the same surface operator with a given Levi type are related by a 2d analogue of the Seiberg duality. The index of this coupled system is computed by using the tools developed in the first half of the paper. The superconformal index in the presence of surface defect is expected to be invariant under generalized S-duality. We demonstrate that it is indeed the case. In doing so the Seiberg-type duality of the 2d theory plays an important role.
Institute of Scientific and Technical Information of China (English)
罗孟波; 陈庆虎; 许祝安; 焦正宽
2001-01-01
The second-order phase transition in the two-dimensional (2D) classical Coulomb gas of half-integer charges on a square lattice is investigated by using Monte Carlo simulations. Based on the finite-size scaling analysis,we estimate the second-order phase transition temperature Tc and the static critical exponents β and v with a new numerical analysis method. More precise critical temperature Tc = 0.1311(2) and critical exponents β/ν = 0.1152(12) and ν = 0.857(15) are obtained. The estimated value of ν indicates that the charge lattice melting transition is different from the pure 2D Ising transition.
2-D DOA Estimation Based on 2D-MUSIC%基于2D-MUSIC算法的DOA估计
Institute of Scientific and Technical Information of China (English)
康亚芳; 王静; 张清泉; 行小帅
2014-01-01
This paper discussed the performance of classical two-dimensional DOA estimation with 2D-MUSIC, based on the mathematical model of planar array and 2D-MUSIC DOA estimation, Taking uniform planar array for example, comput-er simulation experiment was carried for the effect of three kinds of different parameters on 2-D DOA estimation, and the simulation results were analyzed. And also verification test about the corresponding algorithm performance under the differ-ent parameters was discussed.%利用经典的2D-MUSIC算法对二维阵列的DOA估计进行了研究，在平面阵列数学模型以及2D-MUSIC算法的DOA估计模型基础上，以均匀平面阵列为例，对3种不同参数的DOA估计进行了计算机仿真，分析了仿真结果。得出了在不同参数变化趋势下DOA估计的相应变化情况。
Heavy ion reactions around the Coulomb barrier
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The ex perimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the Coulomb barrier are measured and analyzed within a semi-classical model. The obvious effect of positive Q-value multi-neutron transfers on the sub-barrier fusion enhancement is observed in the 32S+96Zr system. In addition, the excitation functions of quasi-elastic scattering at a backward angle have been measured with high precision for the systems of 16O+208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. Considering the deformed coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. The elastic scattering angular distribution of 17F+12C at 60 MeV is measured and calculated by using the continuum-discretized coupled-channels (CDCC) approach. It is found that the diffuseness parameter of the real part of core-target potential has to be increased by 20% to reproduce the experimental result, which corresponds to an increment of potential depth at the surface re gion. The breakup cross section and the coupling between breakup and elastic scattering are small.
Coulomb excitation of {sup 8}Li
Energy Technology Data Exchange (ETDEWEB)
Assuncao, Marlete; Britos, Tatiane Nassar [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Dept. de Ciencias Exatas e da Terra; Descouvemont, Pierre [Universite Libre de Bruxelles (ULB), Brussels (Belgium). Physique Nucleaire Theorique et Physique Mathematique; Lepine-Szily, Alinka; Lichtenthaler Filho, Rubens; Barioni, Adriana; Silva, Diego Medeiros da; Pereira, Dirceu; Mendes Junior, Djalma Rosa; Pires, Kelly Cristina Cezaretto; Gasques, Leandro Romero; Morais, Maria Carmen; Added, Nemitala; Neto Faria, Pedro; Rec, Rafael [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear
2012-07-01
Full text: This work shows the Coulomb Excitation of {sup 8}Li on targets that have effectively behavior of Rutherford in angles and energies of interest for determining the value of the B(E2) electromagnetic transition. Theoretical aspects involved in this type of measure, known as COULEX [1], and some results in the literature [2-3] will be presented. Some problems with the targets and measurement system while performing an experiment on Coulomb Excitation of {sup 8}Li will be discussed: the energy resolution, background, possible contributions of the primary beam and also the excited states of the target near the region of elastic and inelastic peaks. They will be illustrated by measurements of the Coulomb Excitation of {sup 8}Li on targets of {sup 197}Au and {sup 208}Pb using the system RIBRAS(Brazilian Radioactive Ion Beam). In this case, the {sup 8}Li beam(T{sub 1/2} = 838 ms)is produced by {sup 9}Be({sup 7}Li;{sup 8} Li){sup 8}Be reaction from RIBRAS system which is installed at Instituto de Fisica of the Universidade de Sao Paulo. The primary {sup 7L}i beam is provided by Pelletron Accelerator. [1] K. Alder and A. Winther, Electromagnetic Excitation, North-Holland, New York, 1975; [2] P. Descouvemont and D. Baye, Phys. Letts. B 292, 235-238, 1992; [3] J. A. Brown, F. D. Becchetti, J. W. Jaenecke, K, Ashktorab, and D. A. Roberts, J. J. Kolata, R. J. Smith, and K. Lamkin, R. E. Warner, Phys. Rev. Letts., 66, 19, 1991; [4] R. J. Smith, J. J Kolata, K. Lamkin and A. Morsard, F. D. Becchetti, J. A. Brown, W. Z. Liu, J. W. Jaenecke, and D. A. Roberts, R. E. Warner, Phys. Rev. C, 43, 5, 1991. (author)
Overlap Quark Propagator in Coulomb Gauge QCD
Mercado, Ydalia Delgado; Schröck, Mario
2014-01-01
The chirally symmetric Overlap quark propagator is explored in Coulomb gauge. This gauge is well suited for studying the relation between confinement and chiral symmetry breaking, since confinement can be attributed to the infrared divergent Lorentz-vector dressing function. Using quenched gauge field configurations on a $20^4$ lattice, the quark propagator dressing functions are evaluated, the dynamical quark mass is extracted and the chiral limit of these quantities is discussed. By removing the low-lying modes of the Dirac operator, chiral symmetry is artificially restored. Its effect on the dressing functions is discussed.
Nanoplasmonic renormalization and enhancement of Coulomb interactions
Energy Technology Data Exchange (ETDEWEB)
Durach, M; Rusina, A; Stockman, M I [Department of Physics and Astronomy, Georgia State University, Atlanta, GA (United States); Klimov, V I [Chemistry Division, C-PCS, Los Alamos National Laboratory, Los Alamos, NM (United States)], E-mail: mstockman@gsu.edu
2008-10-15
In this paper, we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing the dressed interaction explicitly for an important example of metal-dielectric nanoshells which exhibits a rich resonant behavior in magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced Foerster resonant energy transfer (FRET) between nanocrystal quantum dots near a nanoshell.
Coulomb drag in multiwall armchair carbon nanotubes
DEFF Research Database (Denmark)
Lunde, A.M.; Jauho, Antti-Pekka
2004-01-01
We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...
Nanoplasmonic renormalization and enhancement of Coulomb interactions
Durach, M.; Rusina, A.; Klimov, V. I.; Stockman, M. I.
2008-10-01
In this paper, we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing the dressed interaction explicitly for an important example of metal-dielectric nanoshells which exhibits a rich resonant behavior in magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced Förster resonant energy transfer (FRET) between nanocrystal quantum dots near a nanoshell.
Coulombic dragging of molecular assemblies on nanotubes
Kral, Petr; Sint, Kyaw; Wang, Boyang
2009-03-01
We show by molecular dynamics simulations that polar molecules, ions and their assemblies could be Coulombically dragged on the surfaces of single-wall carbon and boron-nitride nanotubes by ionic solutions or individual ions moving inside the nanotubes [1,2]. We also briefly discuss highly selective ionic sieves based on graphene monolayers with nanopores [3]. These phenomena could be applied in molecular delivery, separation and desalination.[3pt] [1] Boyang Wang and Petr Kral, JACS 128, 15984 (2006). [0pt] [2] Boyang Wang and Petr Kral, Phys. Rev. Lett. 101, 046103 (2008). [0pt] [3] Kyaw Sint, Boyang Wang and Petr Kral, JACS, ASAP (2008).
Action principle for Coulomb collisions in plasmas
Hirvijoki, Eero
2016-09-01
An action principle for Coulomb collisions in plasmas is proposed. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth-MacDonald-Judd potentials. Conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles.
Action principle for Coulomb collisions in plasmas
Hirvijoki, Eero
2015-01-01
In this letter we derive an action principle for Coulomb collisions in plasmas. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth potentials. Exact conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles. Being suitable for discretization, the presented action allows construction of variational integrators. Numerical implementation is left for a future study.
Resonances in the two centers Coulomb system
Energy Technology Data Exchange (ETDEWEB)
Seri, Marcello
2012-09-14
In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.
Coulomb field in a constant electromagnetic background
Adorno, T C; Shabad, A E
2016-01-01
Nonlinear Maxwell equations are written up to the third-power deviations from a constant-field background, valid within any local nonlinear electrodynamics including QED with Euler-Heisenberg effective Lagrangian. Linear electric response to imposed static finite-sized charge is found in the vacuum filled by an arbitrary combination of constant and homogeneous electric and magnetic fields. The modified Coulomb field, corrections to the total charge and to the charge density are given in terms of derivatives of the effective Lagrangian with respect to the field invariants.
Effect of Coulomb collision on the negative ion extraction mechanism in negative ion sources
Energy Technology Data Exchange (ETDEWEB)
Goto, I., E-mail: goto@ppl.appi.keio.ac.jp; Nishioka, S.; Abe, S.; Hatayama, A. [Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Miyamoto, K. [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Mattei, S.; Lettry, J. [CERN, 1211 Geneva 23 (Switzerland)
2016-02-15
To improve the H{sup −} ion beam optics, it is necessary to understand the energy relaxation process of surface produced H{sup −} ions in the extraction region of Cs seeded H{sup −} ion sources. Coulomb collisions of charged particles have been introduced to the 2D3V-PIC (two dimension in real space and three dimension in velocity space particle-in-cell) model for the H{sup −} extraction by using the binary collision model. Due to Coulomb collision, the lower energy part of the ion energy distribution function of H{sup −} ions has been greatly increased. The mean kinetic energy of the surface produced H{sup −} ions has been reduced to 0.65 eV from 1.5 eV. It has been suggested that the beam optics of the extracted H{sup −} ion beam is strongly affected by the energy relaxation process due to Coulomb collision.
New approach to folding with the Coulomb wave function
Energy Technology Data Exchange (ETDEWEB)
Blokhintsev, L. D.; Savin, D. A. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Kadyrov, A. S. [Department of Physics, Astronomy and Medical Radiation Sciences, Curtin University, GPO Box U1987, Perth 6845 (Australia); Mukhamedzhanov, A. M. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States)
2015-05-15
Due to the long-range character of the Coulomb interaction theoretical description of low-energy nuclear reactions with charged particles still remains a formidable task. One way of dealing with the problem in an integral-equation approach is to employ a screened Coulomb potential. A general approach without screening requires folding of kernels of the integral equations with the Coulomb wave. A new method of folding a function with the Coulomb partial waves is presented. The partial-wave Coulomb function both in the configuration and momentum representations is written in the form of separable series. Each term of the series is represented as a product of a factor depending only on the Coulomb parameter and a function depending on the spatial variable in the configuration space and the momentum variable if the momentum representation is used. Using a trial function, the method is demonstrated to be efficient and reliable.
2d Index and Surface operators
Gadde, Abhijit
2013-01-01
In this paper we compute the superconformal index of 2d (2,2) supersymmetric gauge theories. The 2d superconformal index, a.k.a. flavored elliptic genus, is computed by a unitary matrix integral much like the matrix integral that computes 4d superconformal index. We compute the 2d index explicitly for a number of examples. In the case of abelian gauge theories we see that the index is invariant under flop transition and CY-LG correspondence. The index also provides a powerful check of the Seiberg-type duality for non-abelian gauge theories discovered by Hori and Tong. In the later half of the paper, we study half-BPS surface operators in N=2 superconformal gauge theories. They are engineered by coupling the 2d (2,2) supersymmetric gauge theory living on the support of the surface operator to the 4d N=2 theory, so that different realizations of the same surface operator with a given Levi type are related by a 2d analogue of the Seiberg duality. The index of this coupled system is computed by using the tools de...
Coulomb effects in Fermi {beta} decay of {sup 74}Rb
Energy Technology Data Exchange (ETDEWEB)
Oinonen, M. [CERN, EP Div., Geneva (Switzerland)
2003-07-01
Coulomb effects in the {beta} decay of {sup 74}Rb have been studied at ISOLDE. The observation of the non-analog feeding in the {beta} decay allows for an estimation of the Coulomb mixing parameter {delta}{sub IM}{sup 1}. The analysis of the total Coulomb correction {delta}{sub C} is still hampered by the uncertainty in the decay energy. (orig.)
The proton-proton scattering without Coulomb force renormalization
Directory of Open Access Journals (Sweden)
Glöckle W.
2010-04-01
Full Text Available We demonstrate numerically that proton-proton (pp scattering observables can be determined directly by standard short range methods using a screened pp Coulomb force without renormalization. We numerically investigate solutions of the 3-dimensional Lippmann-Schwinger (LS equation for an exponentially screened Coulomb potential. For the limit of large screening radii we conﬁrm analytically predicted properties for oﬀ-shell, half-shell and on-shell elements of the Coulomb t-matrix.
Reconciling Coulomb breakup and neutron radiative capture
Capel, P.; Nollet, Y.
2017-07-01
The Coulomb-breakup method to extract the cross section for neutron radiative capture at astrophysical energies is analyzed in detail. In particular, its sensitivity to the description of the neutron-core continuum is ascertained. We consider the case of 14C(n ,γ )15C for which both the radiative capture at low energy and the Coulomb breakup of 15C into 14C+n on Pb at 68 MeV/nucleon have been measured with accuracy. We confirm the direct proportionality of the cross section for both reactions to the square of the asymptotic normalization constant of 15C observed by Summers and Nunes [Phys. Rev. C 78, 011601(R) (2008), 10.1103/PhysRevC.78.011601], but we also show that the 14C-n continuum plays a significant role in the calculations. Fortunately, the method proposed by Summers and Nunes can be improved to absorb that continuum dependence. We show that a more precise radiative-capture cross section can be extracted selecting the breakup data at forward angles and low 14C-n relative energies.
Coulomb excitation of radioactive {sup 79}Pb
Energy Technology Data Exchange (ETDEWEB)
Lister, C.J.; Blumenthal, D.; Davids, C.N. [and others
1995-08-01
The technical challenges expected in experiments with radioactive beams can already be explored by using ions produced in primary reactions. In addition, the re-excitation of these ions by Coulomb excitation allows a sensitive search for collective states that are well above the yrast line. We are building an experiment to study Coulomb excitation of radioactive ions which are separated from beam particles by the Fragment Mass Analyzer. An array of gamma detectors will be mounted at the focal plane to measure the gamma radiation following re-excitation. Five Compton-suppressed Ge detectors and five planar LEPS detectors will be used. The optimum experiment of this type appears to be the study of {sup 79}Rb following the {sup 24}Mg ({sup 58}Ni,3p) reaction. We calculate that about 5 x 10{sup 5} {sup 79}Rb nuclei/second will reach the excitation foil. This rubidium isotope was selected for study as it is strongly produced and is highly deformed, so easily re-excited. The use of a {sup 58}Ni re-excitation foil offers the best yields. After re-excitation the ions will be subsequently transported into a shielded beamdump to prevent the accumulation of activity.
Transport Through a Coulomb Blockaded Majorana Nanowire
Zazunov, Alex; Egger, Reinhold; Yeyati, Alfredo Levy; Hützen, Roland; Braunecker, Bernd
In one-dimensional (1D) quantum wires with strong spin-orbit coupling and a Zeeman field, a superconducting substrate can induce zero-energy Majorana bound states located near the ends of the wire. We study electronic properties when such a wire is contacted by normal metallic or superconducting electrodes. A special attention is devoted to Coulomb blockade effects. We analyze the "Majorana single-charge transistor" (MSCT), i.e., a floating Majorana wire contacted by normal metallic source and drain contacts, where charging effects are important. We describe Coulomb oscillations in this system and predict that Majorana fermions could be unambiguously detected by the emergence of sideband peaks in the nonlinear differential conductance. We also study a superconducting variant of the MSCT setup with s-wave superconducting (instead of normal-conducting) leads. In the noninteracting case, we derive the exact current-phase relation (CPR) and find π-periodic behavior with negative critical current for weak tunnel couplings. Charging effects then cause the anomalous CPR I(\\varphi ) = Ic\\cos \\varphi, where the parity-sensitive critical current I c provides a signature for Majorana states.
Optical modulators with 2D layered materials
Sun, Zhipei; Martinez, Amos; Wang, Feng
2016-04-01
Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that 2D layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this Review, we cover the state of the art of optical modulators based on 2D materials, including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as 2D heterostructures, plasmonic structures, and silicon and fibre integrated structures. We also take a look at the future perspectives and discuss the potential of yet relatively unexplored mechanisms, such as magneto-optic and acousto-optic modulation.
Automatic Contour Extraction from 2D Image
Directory of Open Access Journals (Sweden)
Panagiotis GIOANNIS
2011-03-01
Full Text Available Aim: To develop a method for automatic contour extraction from a 2D image. Material and Method: The method is divided in two basic parts where the user initially chooses the starting point and the threshold. Finally the method is applied to computed tomography of bone images. Results: An interesting method is developed which can lead to a successful boundary extraction of 2D images. Specifically data extracted from a computed tomography images can be used for 2D bone reconstruction. Conclusions: We believe that such an algorithm or part of it can be applied on several other applications for shape feature extraction in medical image analysis and generally at computer graphics.
Orthotropic Piezoelectricity in 2D Nanocellulose
García, Y.; Ruiz-Blanco, Yasser B.; Marrero-Ponce, Yovani; Sotomayor-Torres, C. M.
2016-10-01
The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V‑1, ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies.
2D microwave imaging reflectometer electronics
Energy Technology Data Exchange (ETDEWEB)
Spear, A. G.; Domier, C. W., E-mail: cwdomier@ucdavis.edu; Hu, X.; Muscatello, C. M.; Ren, X.; Luhmann, N. C. [Electrical and Computer Engineering, University of California, Davis, California 95616 (United States); Tobias, B. J. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2014-11-15
A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.
Effect of Coulomb interaction on multi-electronwave packet dynamics
Energy Technology Data Exchange (ETDEWEB)
Shiokawa, T. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571 (Japan); Takada, Y. [Faculty of Engineering, Tokyo University of Science, Chiyoda, Tokyo, 102-0073, Japan and CREST, Japan Science and Technology Agency (Japan); Konabe, S.; Hatsugai, Y. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and CREST, Japan Science and Technology Agency (Japan); Muraguchi, M. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and CREST, Japan Science and Technology Agency (Japan); Endoh, T. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and Center for Spintronics Integrated Systems, Tohoku University, Sendai, 980-8577, Japan and CREST, Japan Science and Technology Agency (Japan); Shiraishi, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and Center for Computational Science, University of Tsukuba, Tsukuba, 305-8577, Japan and CREST, Japan Science and Technology Agency (Japan)
2013-12-04
We have investigated the effect of Coulomb interaction on electron transport in a one-dimensional nanoscale structure using a multi-electron wave packet approach. To study the time evolution, we numerically solve the time-dependent Hartree-Fock equation, finding that the electron wave packet dynamics strongly depends on the Coulomb interaction strength. When the Coulomb interaction is large, each electron wave packet moves separately in the presence of an electric field. With weak Coulomb interaction, however, the electron wave packets overlap, forming and moving as one collective wave packet.
Assessing 2D electrophoretic mobility spectroscopy (2D MOSY) for analytical applications.
Fang, Yuan; Yushmanov, Pavel V; Furó, István
2016-12-08
Electrophoretic displacement of charged entity phase modulates the spectrum acquired in electrophoretic NMR experiments, and this modulation can be presented via 2D FT as 2D mobility spectroscopy (MOSY) spectra. We compare in various mixed solutions the chemical selectivity provided by 2D MOSY spectra with that provided by 2D diffusion-ordered spectroscopy (DOSY) spectra and demonstrate, under the conditions explored, a superior performance of the former method. 2D MOSY compares also favourably with closely related LC-NMR methods. The shape of 2D MOSY spectra in complex mixtures is strongly modulated by the pH of the sample, a feature that has potential for areas such as in drug discovery and metabolomics. Copyright © 2016 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd. StartCopTextCopyright © 2016 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.
Influence of long-range Coulomb interaction in velocity map imaging
Barillot, T.; Brédy, R.; Celep, G.; Cohen, S.; Compagnon, I.; Concina, B.; Constant, E.; Danakas, S.; Kalaitzis, P.; Karras, G.; Lépine, F.; Loriot, V.; Marciniak, A.; Predelus-Renois, G.; Schindler, B.; Bordas, C.
2017-07-01
The standard velocity-map imaging (VMI) analysis relies on the simple approximation that the residual Coulomb field experienced by the photoelectron ejected from a neutral or ion system may be neglected. Under this almost universal approximation, the photoelectrons follow ballistic (parabolic) trajectories in the externally applied electric field, and the recorded image may be considered as a 2D projection of the initial photoelectron velocity distribution. There are, however, several circumstances where this approximation is not justified and the influence of long-range forces must absolutely be taken into account for the interpretation and analysis of the recorded images. The aim of this paper is to illustrate this influence by discussing two different situations involving isolated atoms or molecules where the analysis of experimental images cannot be performed without considering long-range Coulomb interactions. The first situation occurs when slow (meV) photoelectrons are photoionized from a neutral system and strongly interact with the attractive Coulomb potential of the residual ion. The result of this interaction is the formation of a more complex structure in the image, as well as the appearance of an intense glory at the center of the image. The second situation, observed also at low energy, occurs in the photodetachment from a multiply charged anion and it is characterized by the presence of a long-range repulsive potential. Then, while the standard VMI approximation is still valid, the very specific features exhibited by the recorded images can be explained only by taking into consideration tunnel detachment through the repulsive Coulomb barrier.
Structure Theory for Extended Kepler-Coulomb 3D Classical Superintegrable Systems
Directory of Open Access Journals (Sweden)
Ernie G. Kalnins
2012-06-01
Full Text Available The classical Kepler-Coulomb system in 3 dimensions is well known to be 2nd order superintegrable, with a symmetry algebra that closes polynomially under Poisson brackets. This polynomial closure is typical for 2nd order superintegrable systems in 2D and for 2nd order systems in 3D with nondegenerate (4-parameter potentials. However the degenerate 3-parameter potential for the 3D extended Kepler-Coulomb system (also 2nd order superintegrable is an exception, as its quadratic symmetry algebra doesn't close polynomially. The 3D 4-parameter potential for the extended Kepler-Coulomb system is not even 2nd order superintegrable. However, Verrier and Evans (2008 showed it was 4th order superintegrable, and Tanoudis and Daskaloyannis (2011 showed that in the quantum case, if a second 4th order symmetry is added to the generators, the double commutators in the symmetry algebra close polynomially. Here, based on the Tremblay, Turbiner and Winternitz construction, we consider an infinite class of classical extended Kepler-Coulomb 3- and 4-parameter systems indexed by a pair of rational numbers (k_1,k_2 and reducing to the usual systems when k_1=k_2=1. We show these systems to be superintegrable of arbitrarily high order and work out explicitly the structure of the symmetry algebras determined by the 5 basis generators we have constructed. We demonstrate that the symmetry algebras close rationally; only for systems admitting extra discrete symmetries is polynomial closure achieved. Underlying the structure theory is the existence of raising and lowering constants of the motion, not themselves polynomials in the momenta, that can be employed to construct the polynomial symmetries and their structure relations.
Meso-scale controlled motion for a microfluidic drop ejector.
Energy Technology Data Exchange (ETDEWEB)
Galambos, Paul C.; Givler, Richard C.; Pohl, Kenneth Roy; Czaplewski, David A.; Luck, David L.; Braithwaite, Mark J.; Atwood, Clinton L.; Benavides, Gilbert Lawrence
2004-12-01
The objective of this LDRD was to develop a uniquely capable, novel droplet solution based manufacturing system built around a new MEMS drop ejector. The development all the working subsystems required was completed, leaving the integration of these subsystems into a working prototype still left to accomplish. This LDRD report will focus on the three main subsystems: (1) MEMS drop ejector--the MEMS ''sideshooter'' effectively ejected 0.25 pl drops at 10 m/s, (2) packaging--a compact ejector package based on a modified EMDIP (Electro-Microfluidic Dual In-line Package--SAND2002-1941) was fabricated, and (3) a vision/stage system allowing precise ejector package positioning in 3 dimensions above a target was developed.
Seabed Geoacoustic Structure at the Meso-Scale
2013-09-30
SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report ( SAR ) 18. NUMBER...vehicle, J. Acoust. Soc. Am., 131, 1066-1078, 2012. [published, refereed] Holland, C.W., C.M. Smith, and P.L. Nielsen, Bistatic seabed scattering
Borneo Vortex and Meso-scale Convective Rainfall
Koh, T. Y.; Koseki, S.; Teo, C. K.
2014-12-01
We have investigated how the Borneo vortex develops over the equatorial South China Sea under cold surge conditions in December during the Asian winter monsoon. Composite analysis using reanalysis and satellite datasets has revealed that absolute vorticity and water vapour are transported by strong cold surges from upstream of the South China Sea to around the equator. Rainfall is correspondingly enhanced over the equatorial South China Sea. A semi-idealized experiment reproduced the Borneo vortex over the equatorial South China Sea during a perpetual cold surge. The Borneo vortex is manifested as a meso-alpha cyclone with a comma-shaped rainband in the northeast sector of the cyclone. Vorticity budget analysis showed that the growth/maintenance of the meso-alpha cyclone was achieved mainly by the vortex stretching. This vortex stretching is due to the upward motion forced by the latent heat release around the cyclone centre. The comma-shaped rainband consists of clusters of meso-beta scale rainfall cells. The intense rainfall in the comma-head (comma-tail) is generated by the confluence of the warmer and wetter cyclonic easterly flow (cyclonic southeasterly flow) and the cooler and drier northeasterly surge in the northwestern (northeastern) sector of the cyclone. Intense upward motion and heavy rainfall resulted due to the low-level convergence and the favourable thermodynamic profile at the confluence zone. In particular, the convergence in the northwestern sector is responsible for maintenance of the meso-alpha cyclone system. At both meso-alpha and meso-beta scales, the convergence is ultimately caused by the deviatoric strain in the confluence wind pattern but is significantly self-enhanced by the nonlinear dynamics. Reference: Koseki, S., T.-Y. Koh and C.-K. Teo (2014), Atmospheric Chemistry and Physics, 14, 4539-4562, doi:10.5194/acp-14-4539-2014, 2014.
Impact Response of Granular Material at Global and Meso Scales
2013-02-01
nO/ displays curendy valid OMB DOrUOI nunber. PlEASE DO NOT Rl!TVRN YOUR FORM TO THE .A BOY £ ADDRESS. 1. REPORT DATE (00-MM-YYYY) 12. REPORT TYPE...by flash x-ray. To observe variations in impact-induced pressure inside the sand target, we developed thin pressure sensors that are embedded in... flash -X-ray system was integrated with the target chamber of the gas gun. To measure the cavity size opened up by the projectile in the target, a
Studying geometric structures in meso-scale flows
Directory of Open Access Journals (Sweden)
Christos H. Halios
2014-11-01
Full Text Available Geometric shapes of coherent structures such as ramp or cliff like signals, step changes and waves, are commonly observed in meteorological temporal series and dominate the turbulent energy and mass exchange between the atmospheric surface layer and the layers above, and also relate with low-dimensional chaotic systems. In this work a simple linear technique to extract geometrical shapes has been applied at a dataset which was obtained at a location experiencing a number of different mesoscale modes. It was found that the temperature field appears much better organized than the wind field, and that cliff-ramp structures are dominant in the temperature time series. The occurrence of structural shapes was related with the dominant flow patterns and the status of the flow field. Temperature positive cliff-ramps and ramp-cliffs appear mainly during night time and under weak flow field, while temperature step and sine structures do not show a clear preference for the period of day, flow or temperature pattern. Uniformly stable, weak flow conditions dominate across all the wind speed structures. A detailed analysis of the flow field during two case studies revealed that structural shapes might be part of larger flow structures, such as a sea-breeze front or down-slope winds. During stagnant conditions structural shapes that were associated with deceleration of the flow were observed, whilst during ventilation conditions shapes related with the acceleration of the flow.
Meso-scale FE modelling of structurally stitched preform
Koissin, V.; Lomov, S.V.; Verpoest, I.
2007-01-01
This article addresses the finite-element (FE) analysis of a local fibre placement in a stitched fibrous mat. The term “structural” presumes here that the stitching yarn is relatively thick (contrary to a non-structural NCF kniting) and its fibre stiffness is much higher than the matrix stiffness (p
Borneo vortex and meso-scale convective rainfall
Directory of Open Access Journals (Sweden)
S. Koseki
2013-08-01
Full Text Available We have investigated how the Borneo vortex develops over the equatorial South China Sea under cold surge conditions in December during the Asian winter monsoon. Composite analysis using reanalysis and satellite datasets has revealed that absolute vorticity and water vapour are transported by strong cold surges from upstream of the South China Sea to around the equator. Rainfall is correspondingly enhanced over the equatorial South China Sea. A semi-idealized experiment reproduced the Borneo vortex over the equatorial South China Sea during a "perpetual" cold surge. The Borneo vortex is manifested as a meso-α cyclone with a comma-shaped rainband in the northeast sector of the cyclone. Vorticity budget analysis showed that the growth of the meso-α cyclone was achieved mainly by vortex stretching. The comma-shaped rainband consists of clusters of meso-β scale rainfall patches. The warm and wet cyclonic southeasterly flow meets with the cold and dry northeasterly surge forming a confluence front in the northeastern sector of the cyclone. Intense upward motion and heavy rainfall result both due to the low-level convergence and the favourable thermodynamic profile at the confluence front. At both meso-α and meso-β scales, the convergence is ultimately caused by the deviatoric strain in the confluence wind pattern but is much enhanced by nonlinear self-enhancement dynamics.
Aircraft height estimation using 2-D radar
CSIR Research Space (South Africa)
Hakl, H
2010-01-01
Full Text Available A method to infer height information from an aircraft tracked with a single 2-D search radar is presented. The method assumes level flight in the target aircraft and a good estimate of the speed of the aircraft. The method yields good results...
Canonical structure of 2D black holes
Navarro-Salas, J; Talavera, C F
1994-01-01
We determine the canonical structure of two-dimensional black-hole solutions arising in $2D$ dilaton gravity. By choosing the Cauchy surface appropriately we find that the canonically conjugate variable to the black hole mass is given by the difference of local (Schwarzschild) time translations at right and left spatial infinities. This can be regarded as a generalization of Birkhoff's theorem.
DEFF Research Database (Denmark)
Andersen, Thomas Lykke; Frigaard, Peter
This report present the results of 2D physical model tests carried out in the shallow wave flume at Dept. of Civil Engineering, Aalborg University (AAU), on behalf of Energy E2 A/S part of DONG Energy A/S, Denmark. The objective of the tests was: to investigate the combined influence of the pile...
2D PIM Simulation Based on COMSOL
DEFF Research Database (Denmark)
Wang, Xinbo; Cui, Wanzhao; Wang, Jingyu;
2011-01-01
Passive intermodulation (PIM) is a problematic type of nonlinear distortion en- countered in many communication systems. To analyze the PIM distortion resulting from ma- terial nonlinearity, a 2D PIM simulation method based on COMSOL is proposed in this paper. As an example, a rectangular wavegui...
Roton Excitations and the Fluid-Solid Phase Transition in Superfluid 2D Yukawa Bosons
Molinelli, S.; Galli, D. E.; Reatto, L.; Motta, M.
2016-10-01
We compute several ground-state properties and the dynamical structure factor of a zero-temperature system of Bosons interacting with the 2D screened Coulomb (2D-SC) potential. We resort to the exact shadow path integral ground state (SPIGS) quantum Monte Carlo method to compute the imaginary-time correlation function of the model, and to the genetic algorithm via falsification of theories (GIFT) to retrieve the dynamical structure factor. We provide a detailed comparison of ground-state properties and collective excitations of 2D-SC and ^4He atoms. The roton energy of the 2D-SC system is an increasing function of density, and not a decreasing one as in ^4He. This result is in contrast with the view that the roton is the soft mode of the fluid-solid transition. We uncover a remarkable quasi-universality of backflow and of other properties when expressed in terms of the amount of short-range order as quantified by the height of the first peak of the static structure factor.
Elastic Coulomb breakup of 34Na
Singh, G.; Shubhchintak, Chatterjee, R.
2016-08-01
Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our
Coulomb crystallization in classical and quantum systems
Bonitz, Michael
2007-11-01
Coulomb crystallization occurs in one-component plasmas when the average interaction energy exceeds the kinetic energy by about two orders of magnitude. A simple road to reach such strong coupling consists in using external confinement potentials the strength of which controls the density. This has been succsessfully realized with ions in traps and storage rings and also in dusty plasma. Recently a three-dimensional spherical confinement could be created [1] which allows to produce spherical dust crystals containing concentric shells. I will give an overview on our recent results for these ``Yukawa balls'' and compare them to experiments. The shell structure of these systems can be very well explained by using an isotropic statically screened pair interaction. Further, the thermodynamic properties of these systems, such as the radial density distribution are discussed based on an analytical theory [3]. I then will discuss Coulomb crystallization in trapped quantum systems, such as mesoscopic electron and electron hole plasmas in coupled layers [4,5]. These systems show a very rich correlation behavior, including liquid and solid like states and bound states (excitons, biexcitons) and their crystals. On the other hand, also collective quantum and spin effects are observed, including Bose-Einstein condensation and superfluidity of bound electron-hole pairs [4]. Finally, I consider Coulomb crystallization in two-component neutral plasmas in three dimensions. I discuss the necessary conditions for crystals of heavy charges to exist in the presence of a light component which typically is in the Fermi gas or liquid state. It can be shown that their exists a critical ratio of the masses of the species of the order of 80 [5] which is confirmed by Quantum Monte Carlo simulations [6]. Familiar examples are crystals of nuclei in the core of White dwarf stars, but the results also suggest the existence of other crystals, including proton or α-particle crystals in dense matter
Gauge Theories on the Coulomb Branch
Schwarz, John H.
We construct the world-volume action of a probe D3-brane in AdS5 × S5 with N units of flux. It has the field content, symmetries, and dualities of the U(1) factor of 𝒩 = 4 U(N + 1) super Yang-Mills theory, spontaneously broken to U(N) × U(1) by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a highly effective action (HEA). We construct an SL(2, Z) multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that they reproduce the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a soliton bubble, which is interpreted as a phase boundary.
Gauge Theories on the Coulomb branch
Schwarz, John H
2014-01-01
We construct the world-volume action of a probe D3-brane in $AdS_5 \\times S^5$ with $N$ units of flux. It has the field content, symmetries, and dualities of the $U(1)$ factor of ${\\cal N} =4$ $U(N+1)$ super Yang--Mills theory, spontaneously broken to $U(N) \\times U(1)$ by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a `highly effective action' (HEA). We construct an $SL(2,Z)$ multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that it reproduces the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a `soliton bubble', which is interpreted as a phase boundary.
Coulomb dissociation of light unstable nuclei
Energy Technology Data Exchange (ETDEWEB)
Kido, Toshihiko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Yabana, Kazuhiro; Suzuki, Yoshiyuki
1997-05-01
The aim of this study is that a simulation method applicable to the atomic nucleus with neutron halo structure developed till now is applied to a wider range unstable nucleus containing proton excess nucleus to also attribute understanding of nuclear reaction with interest in astronomical nuclear reaction. The proton dissociation energy in {sup 8}B nucleus is small value of 138 eV, which is thought to have a structure of proton at the most outer shell bound much weakly by core nucleus and spread in thinner thickness. For the coulomb excitation of such weak bound system, quantum theoretical and non-perturbational treatment is important. Therefore, 3-dimensional time-dependent Schroedinger equation on relative wave function of the core nucleus {sup 7}Be and halo proton p will be dissolved in time space and will execute a time developmental simulation. (G.K.)
Ion Coulomb Crystals and Their Applications
Drewsen, Michael
The following text will give a brief introduction to the physics of the spatially ordered structures, so-called Coulomb crystals, that appear when confined ions are cooled to sufficiently low temperatures. It will as well briefly comment on the very diverse scientific applications of such crystals, which have emerged in the past two decades. While this document lacks figures and many specific references, it is the hope, not the text will stimulate the reader to dig deeper into one or more of the discussed subjects, and inspire her/him to think about new potential applications. A fully referenced journal article of essentially the same text can be found in Physica B 460, 105 (2015) [1].
Distorted Coulomb field of the scattered electron
Thomsen, H D; Andersen, K K; Lund, M D; Knudsen, H; Uggerhøj, E; Uggerhøj1, U I; Sona, P; Mangiarotti, A; Ketel, T J; Dizdar, A; Ballestrero, S; Connell, S H
2010-01-01
Experimental results for the radiation emission from ultrarelativistic electrons in targets of 0.03%–5% radiation length is presented. For the thinnest targets, the radiation emission is in accordance with the Bethe-Heitler formulation of bremsstrahlung, the target acting as a single scatterer. In this regime, the radiation intensity is proportional to the thickness. As the thickness increases, the distorted Coulomb field of the electron that is the result of the first scattering events, leads to a suppressed radiation emission per interaction, upon subsequent scattering events. In that case, the radiation intensity becomes proportional to a logarithmic function of the thickness, due to the suppression. Eventually, once the target becomes sufficiently thick, the entire radiation process becomes influenced by multiple scattering and the radiation intensity is again proportional to the thickness, but with a different constant of proportionality. The observed logarithmic thickness dependence of radiation inten...
Relativistic Coulomb scattering of spinless bosons
Garcia, M G
2015-01-01
The relativistic scattering of spin-0 bosons by spherically symmetric Coulomb fields is analyzed in detail with an arbitrary mixing of vector and scalar couplings. It is shown that the partial wave series reduces the scattering amplitude to the closed Rutherford formula exactly when the vector and scalar potentials have the same magnitude, and as an approximation for weak fields. The behavior of the scattering amplitude near the conditions that furnish its closed form is also discussed. Strong suppressions of the scattering amplitude when the vector and scalar potentials have the same magnitude are observed either for particles or antiparticles with low incident momentum. We point out that such strong suppressions might be relevant in the analysis of the scattering of fermions near the conditions for the spin and pseudospin symmetries. From the complex poles of the partial scattering amplitude the exact closed form of bound-state solutions for both particles and antiparticles with different scenarios for the ...
Pair distribution of ions in Coulomb lattice
Witt, H E D; Chugunov, A I; Baiko, D A; Yakovlev, D G
2003-01-01
The pair distribution function g(r) ident to g(x, y, z) and the radial pair distribution function g(r) of ions in body-centred-cubic and face-centred-cubic Coulomb crystals are calculated within the harmonic-lattice (HL) approximation in a wide temperature range, from the high-temperature classical limit (T >> h-bar w sub p , w sub p being the ion plasma frequency) to the low-temperature quantum limit (T || h-bar w sub p). In the classical limit, g(r) is also calculated by the Monte Carlo (MC) method. MC and HL results are demonstrated to be in good agreement. With decreasing T, the correlation peaks of g(r) and g(r) become narrower. At T || h-bar w sub p they become temperature independent (determined by zero-point ion vibrations).
Coulomb crystals in the magnetic field
Baiko, D A
2009-01-01
The body-centered cubic Coulomb crystal of ions in the presence of a uniform magnetic field is studied using the rigid electron background approximation. The phonon mode spectra are calculated for a wide range of magnetic field strengths and for several orientations of the field in the crystal. The phonon spectra are used to calculate the phonon contribution to the crystal energy, entropy, specific heat, Debye-Waller factor of ions, and the rms ion displacements from the lattice nodes for a broad range of densities, temperatures, chemical compositions, and magnetic fields. Strong magnetic field dramatically alters the properties of quantum crystals. The phonon specific heat increases by many orders of magnitude. The ion displacements from their equilibrium positions become strongly anisotropic. The results can be relevant for dusty plasmas, ion plasmas in Penning traps, and especially for the crust of magnetars (neutron stars with superstrong magnetic fields $B \\gtrsim 10^{14}$ G). The effect of the magnetic ...
Thermodynamic Functions of Magnetized Coulomb Crystals
Baiko, D A
2013-01-01
Free energy, internal energy, and specific heat for each of the three phonon spectrum branches of a magnetized Coulomb crystal with body-centered cubic lattice are calculated by numerical integration over the Brillouin zone in the range of magnetic fields $B$ and temperatures $T$, such that $0 \\le \\omega_{\\rm B}/\\omega_{\\rm p}\\le 10^3$ and $10^{-4} \\le T/T_{\\rm p} \\le 10^4$. In this case, $\\omega_{\\rm B}$ is the ion cyclotron frequency, $\\omega_{\\rm p}$ and $T_{\\rm p}$ are the ion plasma frequency and plasma temperature, respectively. The results of numerical calculations are approximated by simple analytical formulas. For illustration, these formulas are used to analyze the behavior of the heat capacity in the crust of a neutron star with strong magnetic field. Thermodynamic functions of magnetized neutron star crust are needed for modeling various observational phenomena in magnetars and high magnetic field pulsars.
Study on Coulomb explosions of ion mixtures
Boella, E; D'Angola, A; Coppa, G; Silva, L O
2015-01-01
The paper presents a theoretical work on the dynamics of Coulomb explosion for spherical nanoplasmas composed by two different ion species. Particular attention has been dedicated to study the energy spectra of the ions with the larger charge-to-mass ratio. The connection between the formation of shock shells and the energy spread of the ions has been the object of a detailed analysis, showing that under particular conditions the width of the asymptotic energy spectrum tends to become very narrow, which leads to a multi-valued ion phase-space. The conditions to generate a quasi mono-energetic ion spectrum have been rigorously demonstrated and verifed by numerical simulations, using a technique that, exploiting the spherical symmetry of the problem, allows one to obtain very accurate and precise results.
Effect of operational parameters on Coulombic efficiency in bioelectrochemical systems
Sleutels, T.H.J.A.; Darus, L.; Hamelers, H.V.M.; Buisman, C.J.N.
2011-01-01
To create an efficient bioelectrochemical system, a high Coulombic efficiency is required. This efficiency is a direct measure for the competition between electrogens and methanogens when acetate is used as substrate. In this study the Coulombic efficiency in a microbial electrolysis cell was invest
Coulomb distortion effects in deep-inelastic electron scattering
Co', Giampaolo; Heisenberg, Jochen
1987-11-01
The effects of the Coulomb distortion of the electron wave functions in the description of the electron scattering processes in the quasi-elastic region are discussed. A method to extract longitudinal and transverse response functions considering these effects is presented. While the transverse response function is remarkably affected by the Coulomb distortion, the values of the longitudinal response function are practically unchanged.
Antilocalization of Coulomb Blockade in a Ge-Si Nanowire
DEFF Research Database (Denmark)
Higginbotham, Andrew P.; Kuemmeth, Ferdinand; Larsen, Thorvald Wadum
2014-01-01
The distribution of Coulomb blockade peak heights as a function of magnetic field is investigated experimentally in a Ge-Si nanowire quantum dot. Strong spin-orbit coupling in this hole-gas system leads to antilocalization of Coulomb blockade peaks, consistent with theory. In particular, the peak...
Spherical Calogero model with oscillator/Coulomb potential: classical case
Correa, Francisco; Lechtenfeld, Olaf; Nersessian, Armen
2016-01-01
We construct the Hamiltonians and symmetry generators of Calogero-oscillator and Calogero-Coulomb models on the N-dimensional sphere within the matrix-model reduction approach. Our method also produces the integrable Calogero-Coulomb-Stark model on the sphere and proves the integrability of the spin extensions of all these systems.
Quantum Dynamics of Biological Plasma in the External Coulomb Field
Lasukov, V. V.; Lasukova, T. V.; Lasukova, O. V.
2013-10-01
A quantum solution to the truncated Fisher-Kolmogorov-Petrovskii-Piskunov equation with Coulomb convection and linear diffusion is derived. The quantum radiation of biological systems, individual microorganisms (cells, bacteria), and dust plasma particles in the Coulomb field is studied using the foregoing solution.
Magneto-Coulomb effect in spin-valve devices
van der Molen, SJ; Tombros, N; van Wees, BJ
2006-01-01
We discuss the influence of the magneto-Coulomb effect (MCE) on the magnetoconductance of spin-valve devices. We show that the MCE can induce magnetoconductances of several percent or more, depending on the strength of the Coulomb blockade. Furthermore, the MCE-induced magnetoconductance changes sig
Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology.
Shavanova, Kateryna; Bakakina, Yulia; Burkova, Inna; Shtepliuk, Ivan; Viter, Roman; Ubelis, Arnolds; Beni, Valerio; Starodub, Nickolaj; Yakimova, Rositsa; Khranovskyy, Volodymyr
2016-02-06
The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct "beyond graphene" domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical). A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials.
Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology
Directory of Open Access Journals (Sweden)
Kateryna Shavanova
2016-02-01
Full Text Available The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D materials. After considerable research effort, a distinct “beyond graphene” domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical. A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials.
Coulomb excitation effects on alpha-particle optical potential below the Coulomb barrier
Avrigeanu, V; Mănăilescu, C
2016-01-01
A competition of the low-energy Coulomb excitation (CE) with the compound nucleus (CN) formation in alpha-induced reactions below the Coulomb barrier has recently been assumed in order to make possible the description of the latter as well as the alpha-particle emission by the same optical model (OM) potential. On the contrary, we show in the present work that the corresponding partial waves and integration radii provide evidence for the distinct account of the CE cross section and OM total-reaction cross section $\\sigma_R$. Thus the largest contribution to CE cross section comes by far from partial waves larger than the ones contributing to the $\\sigma_R$ values.
On the decoupling between classical Coulomb matter and radiation
Alastuey, Angel; Appel, Walter
2000-02-01
We consider a model of matter coupled to radiation at equilibrium. Matter is described by a one-component plasma of classical point charges with Coulomb interactions, while radiation is represented by the classical transverse potential vector in Coulomb gauge. Using a straightforward generalization of the Bohr-van Leeuwen theorem, we show that the equilibrium properties of classical Coulomb matter remain unaffected by the presence of the classical radiation. As far as the real world is concerned, this decoupling does survive at large distances where both matter and radiation can be treated classically. This invalidates all the large-distances predictions, for the charge correlations, of the so-called Darwin models which incorporate retarded electromagnetic interactions beyond the instantaneous Coulomb potential. A second related important consequence is that the first relativistic corrections to the Coulomb thermodynamical quantities must be evaluated within the theory of quantum electrodynamics at finite temperature, even in a weakly relativistic and almost classical regime for matter.
Energy Technology Data Exchange (ETDEWEB)
Bauer, H.
1998-12-31
The scattering system {sup 162}Dy {yields} {sup 116}Sn has been examined at energies in the vicinity of the Coulomb barrier using the Heidelberg-Darmstadt Crystal Ball spectrometer combined with 5 Germanium-CLUSTER detectors. In order to study pairing correlations as a function of angular momentum cold events were selected in the 2n stripping channel by identifying and suppressing the dominant hot part of the transfer with the Crystal Ball. The CLUSTER detectors with their high {gamma}-efficiency were used to identify the transfer channel and to resolve individual final states. Cross sections for the population of individual yrast states in a cold transfer reaction have been measured for the first time indicating the strong influence of higher transfer multipolarities. At small surface distances Coulomb-nuclear interferences were found to be responsible for the stronger decline of the population of higher yrast states in the transfer channel as compared to the Coulex channel. As a preparatory study for 2n transfer measurements between high spin yrast states in the backbending region of deformed nuclei the Coulomb excitation process in the crossing region of two bands in {sup 162}Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)
Schottky diodes from 2D germanane
Sahoo, Nanda Gopal; Esteves, Richard J.; Punetha, Vinay Deep; Pestov, Dmitry; Arachchige, Indika U.; McLeskey, James T.
2016-07-01
We report on the fabrication and characterization of a Schottky diode made using 2D germanane (hydrogenated germanene). When compared to germanium, the 2D structure has higher electron mobility, an optimal band-gap, and exceptional stability making germanane an outstanding candidate for a variety of opto-electronic devices. One-atom-thick sheets of hydrogenated puckered germanium atoms have been synthesized from a CaGe2 framework via intercalation and characterized by XRD, Raman, and FTIR techniques. The material was then used to fabricate Schottky diodes by suspending the germanane in benzonitrile and drop-casting it onto interdigitated metal electrodes. The devices demonstrate significant rectifying behavior and the outstanding potential of this material.
Schottky diodes from 2D germanane
Energy Technology Data Exchange (ETDEWEB)
Sahoo, Nanda Gopal; Punetha, Vinay Deep [Nanoscience and Nanotechnology Centre, Department of Chemistry, Kumaun University, Nainital, 263001 Uttarakhand (India); Esteves, Richard J; Arachchige, Indika U. [Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Pestov, Dmitry [Nanomaterials Core Characterization Center, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); McLeskey, James T., E-mail: JamesMcLeskey@rmc.edu [Department of Physics, Randolph-Macon College, Ashland, Virginia 23005 (United States)
2016-07-11
We report on the fabrication and characterization of a Schottky diode made using 2D germanane (hydrogenated germanene). When compared to germanium, the 2D structure has higher electron mobility, an optimal band-gap, and exceptional stability making germanane an outstanding candidate for a variety of opto-electronic devices. One-atom-thick sheets of hydrogenated puckered germanium atoms have been synthesized from a CaGe{sub 2} framework via intercalation and characterized by XRD, Raman, and FTIR techniques. The material was then used to fabricate Schottky diodes by suspending the germanane in benzonitrile and drop-casting it onto interdigitated metal electrodes. The devices demonstrate significant rectifying behavior and the outstanding potential of this material.
2D Metals by Repeated Size Reduction.
Liu, Hanwen; Tang, Hao; Fang, Minghao; Si, Wenjie; Zhang, Qinghua; Huang, Zhaohui; Gu, Lin; Pan, Wei; Yao, Jie; Nan, Cewen; Wu, Hui
2016-10-01
A general and convenient strategy for manufacturing freestanding metal nanolayers is developed on large scale. By the simple process of repeatedly folding and calendering stacked metal sheets followed by chemical etching, free-standing 2D metal (e.g., Ag, Au, Fe, Cu, and Ni) nanosheets are obtained with thicknesses as small as 1 nm and with sizes of the order of several micrometers.
Smith, Greg; Lankshear, Allan
1998-07-01
2dF is a multi-object instrument mounted at prime focus at the AAT capable of spectroscopic analysis of 400 objects in a single 2 degree field. It also prepares a second 2 degree 400 object field while the first field is being observed. At its heart is a high precision robotic positioner that places individual fiber end magnetic buttons on one of two field plates. The button gripper is carried on orthogonal gantries powered by linear synchronous motors and contains a TV camera which precisely locates backlit buttons to allow placement in user defined locations to 10 (mu) accuracy. Fiducial points on both plates can also be observed by the camera to allow repeated checks on positioning accuracy. Field plates rotate to follow apparent sky rotation. The spectrographs both analyze light from the 200 observing fibers each and back- illuminate the 400 fibers being re-positioned during the observing run. The 2dF fiber position and spectrograph system is a large and complex instrument located at the prime focus of the Anglo Australian Telescope. The mechanical design has departed somewhat from the earlier concepts of Gray et al, but still reflects the audacity of those first ideas. The positioner is capable of positioning 400 fibers on a field plate while another 400 fibers on another plate are observing at the focus of the telescope and feeding the twin spectrographs. When first proposed it must have seemed like ingenuity unfettered by caution. Yet now it works, and works wonderfully well. 2dF is a system which functions as the result of the combined and coordinated efforts of the astronomers, the mechanical designers and tradespeople, the electronic designers, the programmers, the support staff at the telescope, and the manufacturing subcontractors. The mechanical design of the 2dF positioner and spectrographs was carried out by the mechanical engineering staff of the AAO and the majority of the manufacture was carried out in the AAO workshops.
2D-Tasks for Cognitive Rehabilitation
Caballero Hernandez, Ruth; Martinez Moreno, Jose Maria; García Molina, A.; Ferrer Celma, S.; Solana Sánchez, Javier; Sanchez Carrion, R.; Fernandez Casado, E.; Pérez Rodríguez, Rodrigo; Gomez Pulido, A.; Anglès Tafalla, C.; Cáceres Taladriz, César; Ferre Vergada, M.; Roig Rovira, Teresa; Garcia Lopez, P.; Tormos Muñoz, Josep M.
2011-01-01
Neuropsychological Rehabilitation is a complex clinic process which tries to restore or compensate cognitive and behavioral disorders in people suffering from a central nervous system injury. Information and Communication Technologies (ICTs) in Biomedical Engineering play an essential role in this field, allowing improvement and expansion of present rehabilitation programs. This paper presents a set of cognitive rehabilitation 2D-Tasks for patients with Acquired Brain Injury (ABI). These t...
Quasiparticle interference in unconventional 2D systems
Chen, Lan; Cheng, Peng; Wu, Kehui
2017-03-01
At present, research of 2D systems mainly focuses on two kinds of materials: graphene-like materials and transition-metal dichalcogenides (TMDs). Both of them host unconventional 2D electronic properties: pseudospin and the associated chirality of electrons in graphene-like materials, and spin-valley-coupled electronic structures in the TMDs. These exotic electronic properties have attracted tremendous interest for possible applications in nanodevices in the future. Investigation on the quasiparticle interference (QPI) in 2D systems is an effective way to uncover these properties. In this review, we will begin with a brief introduction to 2D systems, including their atomic structures and electronic bands. Then, we will discuss the formation of Friedel oscillation due to QPI in constant energy contours of electron bands, and show the basic concept of Fourier-transform scanning tunneling microscopy/spectroscopy (FT-STM/STS), which can resolve Friedel oscillation patterns in real space and consequently obtain the QPI patterns in reciprocal space. In the next two parts, we will summarize some pivotal results in the investigation of QPI in graphene and silicene, in which systems the low-energy quasiparticles are described by the massless Dirac equation. The FT-STM experiments show there are two different interference channels (intervalley and intravalley scattering) and backscattering suppression, which associate with the Dirac cones and the chirality of quasiparticles. The monolayer and bilayer graphene on different substrates (SiC and metal surfaces), and the monolayer and multilayer silicene on a Ag(1 1 1) surface will be addressed. The fifth part will introduce the FT-STM research on QPI in TMDs (monolayer and bilayer of WSe2), which allow us to infer the spin texture of both conduction and valence bands, and present spin-valley coupling by tracking allowed and forbidden scattering channels.
Engineering light outcoupling in 2D materials
Lien, Derhsien
2015-02-11
When light is incident on 2D transition metal dichalcogenides (TMDCs), it engages in multiple reflections within underlying substrates, producing interferences that lead to enhancement or attenuation of the incoming and outgoing strength of light. Here, we report a simple method to engineer the light outcoupling in semiconducting TMDCs by modulating their dielectric surroundings. We show that by modulating the thicknesses of underlying substrates and capping layers, the interference caused by substrate can significantly enhance the light absorption and emission of WSe2, resulting in a ∼11 times increase in Raman signal and a ∼30 times increase in the photoluminescence (PL) intensity of WSe2. On the basis of the interference model, we also propose a strategy to control the photonic and optoelectronic properties of thin-layer WSe2. This work demonstrates the utilization of outcoupling engineering in 2D materials and offers a new route toward the realization of novel optoelectronic devices, such as 2D LEDs and solar cells.
Irreversibility-inversions in 2D turbulence
Bragg, Andrew; de Lillo, Filippo; Boffetta, Guido
2016-11-01
We consider a recent theoretical prediction that for inertial particles in 2D turbulence, the nature of the irreversibility of their pair dispersion inverts when the particle inertia exceeds a certain value. In particular, when the particle Stokes number, St , is below a certain value, the forward-in-time (FIT) dispersion should be faster than the backward-in-time (BIT) dispersion, but for St above this value, this should invert so that BIT becomes faster than FIT dispersion. This non-trivial behavior arises because of the competition between two physically distinct irreversibility mechanisms that operate in different regimes of St . In 3D turbulence, both mechanisms act to produce faster BIT than FIT dispersion, but in 2D, the two mechanisms have opposite effects because of the inverse energy cascade in the turbulent velocity field. We supplement the qualitative argument given by Bragg et al. by deriving quantitative predictions of this effect in the short-time dispersion limit. These predictions are then confirmed by results of inertial particle dispersion in a direct numerical simulation of 2D turbulence.
2D superconductivity by ionic gating
Iwasa, Yoshi
2D superconductivity is attracting a renewed interest due to the discoveries of new highly crystalline 2D superconductors in the past decade. Superconductivity at the oxide interfaces triggered by LaAlO3/SrTiO3 has become one of the promising routes for creation of new 2D superconductors. Also, the MBE grown metallic monolayers including FeSe are also offering a new platform of 2D superconductors. In the last two years, there appear a variety of monolayer/bilayer superconductors fabricated by CVD or mechanical exfoliation. Among these, electric field induced superconductivity by electric double layer transistor (EDLT) is a unique platform of 2D superconductivity, because of its ability of high density charge accumulation, and also because of the versatility in terms of materials, stemming from oxides to organics and layered chalcogenides. In this presentation, the following issues of electric filed induced superconductivity will be addressed; (1) Tunable carrier density, (2) Weak pinning, (3) Absence of inversion symmetry. (1) Since the sheet carrier density is quasi-continuously tunable from 0 to the order of 1014 cm-2, one is able to establish an electronic phase diagram of superconductivity, which will be compared with that of bulk superconductors. (2) The thickness of superconductivity can be estimated as 2 - 10 nm, dependent on materials, and is much smaller than the in-plane coherence length. Such a thin but low resistance at normal state results in extremely weak pinning beyond the dirty Boson model in the amorphous metallic films. (3) Due to the electric filed, the inversion symmetry is inherently broken in EDLT. This feature appears in the enhancement of Pauli limit of the upper critical field for the in-plane magnetic fields. In transition metal dichalcogenide with a substantial spin-orbit interactions, we were able to confirm the stabilization of Cooper pair due to its spin-valley locking. This work has been supported by Grant-in-Aid for Specially
2-D Prony-Huang Transform: A New Tool for 2-D Spectral Analysis
Schmitt, Jérémy; Borgnat, Pierre; Flandrin, Patrick; Condat, Laurent
2014-01-01
This work proposes an extension of the 1-D Hilbert Huang transform for the analysis of images. The proposed method consists in (i) adaptively decomposing an image into oscillating parts called intrinsic mode functions (IMFs) using a mode decomposition procedure, and (ii) providing a local spectral analysis of the obtained IMFs in order to get the local amplitudes, frequencies, and orientations. For the decomposition step, we propose two robust 2-D mode decompositions based on non-smooth convex optimization: a "Genuine 2-D" approach, that constrains the local extrema of the IMFs, and a "Pseudo 2-D" approach, which constrains separately the extrema of lines, columns, and diagonals. The spectral analysis step is based on Prony annihilation property that is applied on small square patches of the IMFs. The resulting 2-D Prony-Huang transform is validated on simulated and real data.
GBL-2D Version 1.0: a 2D geometry boolean library.
Energy Technology Data Exchange (ETDEWEB)
McBride, Cory L. (Elemental Technologies, American Fort, UT); Schmidt, Rodney Cannon; Yarberry, Victor R.; Meyers, Ray J. (Elemental Technologies, American Fort, UT)
2006-11-01
This report describes version 1.0 of GBL-2D, a geometric Boolean library for 2D objects. The library is written in C++ and consists of a set of classes and routines. The classes primarily represent geometric data and relationships. Classes are provided for 2D points, lines, arcs, edge uses, loops, surfaces and mask sets. The routines contain algorithms for geometric Boolean operations and utility functions. Routines are provided that incorporate the Boolean operations: Union(OR), XOR, Intersection and Difference. A variety of additional analytical geometry routines and routines for importing and exporting the data in various file formats are also provided. The GBL-2D library was originally developed as a geometric modeling engine for use with a separate software tool, called SummitView [1], that manipulates the 2D mask sets created by designers of Micro-Electro-Mechanical Systems (MEMS). However, many other practical applications for this type of software can be envisioned because the need to perform 2D Boolean operations can arise in many contexts.
Extrinsic curvature induced 2-d gravity
Viswanathan, K S
1993-01-01
Abtract: 2-dimensional fermions are coupled to extrinsic geometry of a conformally immersed surface in ${\\bf R}^3$ through gauge coupling. By integrating out the fermions, we obtain a WZNW action involving extrinsic curvature of the surface. Restricting the resulting effective action to surfaces of $h\\sqrt g=1$, an explicit form of the action invariant under Virasaro symmetry is obtained. This action is a sum of the geometric action for the Virasaro group and the light-cone action of 2-d gravity plus an interaction term. The central charges of the theory in both the left and right sectors are calculated.
Temple, Aidan
2013-01-01
Filled with practical, step-by-step instructions and clear explanations for the most important and useful tasks. The step-by-step approach taken by this book will show you how to develop a 2D HTML5 platformer-based game that you will be able to publish to multiple devices.This book is great for anyone who has an interest in HTML5 games development, and who already has a basic to intermediate grasp on both the HTML markup and JavaScript programming languages. Therefore, due to this requirement, the book will not discuss the inner workings of either of these languages but will instead attempt to
Robust and resistant 2D shape alignment
DEFF Research Database (Denmark)
Larsen, Rasmus; Eiriksson, Hrafnkell
2001-01-01
\\_\\$\\backslash\\$infty\\$ norm alignments are formulated as linear programming problems. The linear vector function formulation along with the different norms results in alignment methods that are both resistant from influence from outliers, robust wrt. errors in the annotation and capable of handling missing datapoints......We express the alignment of 2D shapes as the minimization of the norm of a linear vector function. The minimization is done in the \\$l\\_1\\$, \\$l\\_2\\$ and the \\$l\\_\\$\\backslash\\$infty\\$ norms using well known standard numerical methods. In particular, the \\$l\\_1\\$ and the \\$l...
Another solution of 2D Ising model
Vergeles, S. N.
2009-04-01
The partition function of the Ising model on a two-dimensional regular lattice is calculated by using the matrix representation of a Clifford algebra (the Dirac algebra), with number of generators equal to the number of lattice sites. It is shown that the partition function over all loops in a 2D lattice including self-intersecting ones is the trace of a polynomial in terms of Dirac matrices. The polynomial is an element of the rotation group in the spinor representation. Thus, the partition function is a function of a character on an orthogonal group of a high degree in the spinor representation.
Target tracking using a 2D radar
CSIR Research Space (South Africa)
Kriel, M
2012-08-01
Full Text Available is omitted. This can be an important consideration as aircraft altitude limits the attack pro�les a target can��y [1]. 33.2 HEIGHT ESTIMATION The current literature regarding height estimation restricts itself to computations involving two or more 2D... is instrumental in determining the aircraft altitude. The accuracy to which these speeds are known is directly pro- portional to the accuracy to which the altitude can be determined. Knowledge of aircraft speed can be obtained in a variety of ways. For example...
Ionic Coulomb Blockade and Resonant Conduction in Biological Ion Channels
Kaufman, I Kh; Eisenberg, R S
2014-01-01
The conduction and selectivity of calcium/sodium ion channels are described in terms of ionic Coulomb blockade, a phenomenon based on charge discreteness and an electrostatic model of an ion channel. This novel approach provides a unified explanation of numerous observed and modelled conductance and selectivity phenomena, including the anomalous mole fraction effect and discrete conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The model is equally applicable to other nanopores.
Coulomb Breakup of Nucleus 6 Li on Ion 208Pb
Irgaziev, B. F.; ERGASHBAEV, H. T.
1998-01-01
In the framework of the three-body approach the A(a,bc)A Coulomb breakup has been investigated. The three-body Coulomb dynamic is taken into account to derive the expression for the reaction matrix element. The mechanism of the breakup includes the direct process and the excitation of resonance state of the particle a. The calculation of the triple differential cross section of the 208Pb(6Li, a d)208Pb Coulomb dissociation have been performed in the energy region Ea d < 1MeV. Cal...
Theory and simulation of strong correlations in quantum Coulomb systems
Bonitz, M; Filinov, A V; Golubnychiy, V O; Kremp, D; Gericke, D O; Murillo, M S; Filinov, V S; Fortov, V; Hoyer, W; Koch, S W
2003-01-01
Strong correlations in quantum Coulomb systems (QCS) are attracting increasing interest in many fields ranging from dense plasmas and semiconductors to metal clusters and ultracold trapped ions. Examples are bound states in dense plasmas (atoms, molecules, clusters) and semiconductors (excitons, trions, biexcitons) or Coulomb crystals. We present first-principle simulation results of these systems including path integral Monte Carlo simulations of the equilibrium behaviour of dense hydrogen and electron-hole plasmas and molecular dynamics and quantum kinetic theory simulations of the nonequilibrium properties of QCS. Finally, we critically assess potential and limitations of the various methods in their application to Coulomb systems.
Deep inelastic scattering near the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Gehring, J.; Back, B.; Chan, K. [and others
1995-08-01
Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.
Coulomb crystals in the harmonic lattice approximation
Baiko, D A; De Witt, H E; Slattery, W L
2000-01-01
The dynamic structure factor ${\\tilde S}({\\bf k},\\omega)$ and the two-particle distribution function $g({\\bf r},t)$ of ions in a Coulomb crystal are obtained in a closed analytic form using the harmonic lattice (HL) approximation which takes into account all processes of multi-phonon excitation and absorption. The static radial two-particle distribution function $g(r)$ is calculated for classical ($T \\gtrsim \\hbar \\omega_p$, where $\\omega_p$ is the ion plasma frequency) and quantum ($T \\ll \\hbar \\omega_p$) body-centered cubic (bcc) crystals. The results for the classical crystal are in a very good agreement with extensive Monte Carlo (MC) calculations at $1.5 \\lesssim r/a calculated for classical and quantum bcc and face-centered cubic crystals, and anharmonic corrections are discussed. The inelastic part of the HL static structure factor $S''(k)$, averaged over orientations of wave-vector {\\bf k}, is shown to contain pronounced singularities at Bragg diffraction positions. The type of the singularities is di...
Electron attraction mediated by Coulomb repulsion.
Hamo, A; Benyamini, A; Shapir, I; Khivrich, I; Waissman, J; Kaasbjerg, K; Oreg, Y; von Oppen, F; Ilani, S
2016-07-21
One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed 'excitonic', promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the 'glue' that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.
Dirac Hamiltonian with superstrong Coulomb field
Voronov, B L; Tyutin, I V
2006-01-01
We consider the quantum-mechanical problem of a relativistic Dirac particle moving in the Coulomb field of a point charge $Ze$. In the literature, it is often declared that a quantum-mechanical description of such a system does not exist for charge values exceeding the so-called critical charge with Z=137 based on the fact that the standard expression for energy eigenvalues yields complex values at overcritical charges. We show that from the mathematical standpoint, there is no problem in defining a self-adjoint Hamiltonian for any value of charge. What is more, the transition through the critical charge does not lead to any qualitative changes in the mathematical description of the system. A specific feature of overcritical charges is the nonuniqueness of the self-adjoint Hamiltonian, but this nonuniqueness is also characteristic for charge values less than the critical one (and larger than the subcritical charge with Z=118). We present the spectra and (generalized) eigenfunctions for all self-adjoint Hamilt...
Relativistic Coulomb excitation of {sup 88}Kr
Energy Technology Data Exchange (ETDEWEB)
Moschner, Kevin; Blazhev, Andrey; Jolie, Jan; Warr, Nigel; Wendt, Andreas [IKP, Universitaet zu Koeln, 50937 Koeln (Germany); Collaboration: PreSPEC-Collaboration
2015-07-01
Within the scope of the PreSPEC campaign we performed a Coulomb-excitation experiment to determine absolute E2 transition strengths to 2{sup +} states in the radioactive nucleus {sup 88}Kr. The aim of our studies was to identify the one quadruple-phonon mixed-symmetry 2{sub MS}{sup +} state in order to extend our knowledge on these states to lighter N = 52 isotones and to track their evolution over different proton shells. The investigated ions were provided through projectile fission of a 650 MeV {sup 238}U beam on a primary target consisting of 0.6 g/cm{sup 2} {sup 9}Be and subsequent separation and identification of the reaction products via the FRS at GSI. The secondary target consisted of 0.4 g/cm{sup 2} {sup 197}Au. De-exciting γ radiation was detected by the PreSPEC array, consisting of 15 EUROBALL Cluster detectors. The Lund-York-Cologne-CAlorimeter LYCCA was used for particle identification after the secondary target. Absolute transition strengths of the transitions depopulating the 2{sup +}{sub 3} state in {sup 88}Kr which suggest the mixed symmetric character of this state are presented and discussed within the systematics of the N = 52 isotones.
Strong Coulomb Coupling in the Todorov Equation
Bawin, M.; Cugnon, J.; Sazdjian, H.
A positronium-like system with strong Coulomb coupling, considered in its pseudoscalar sector, is studied in the framework of relativistic quantum constraint dynamics with the Todorov choice for the potential. Case’s method of self-adjoint extension of singular potentials, which avoids explicit introduction of regularization cut-offs, is adopted. It is found that, as the coupling constant α increases, the bound state spectrum undergoes an abrupt change at the critical value α=αc=1/2. For α>αc, the mass spectrum displays, in addition to the existing states for α<αc, a new set of an infinite number of bound states concentrated in a narrow band starting at mass W=0; all the states have indefinitely oscillating wave functions near the origin. In the limit α→αc from above, the oscillations disappear and the narrow band of low-lying states shrinks to a single massless state with a mass gap with the rest of the spectrum. This state has the required properties to represent a Goldstone boson and to signal spontaneous breakdown of chiral symmetry.
Electron attraction mediated by Coulomb repulsion
Hamo, A.; Benyamini, A.; Shapir, I.; Khivrich, I.; Waissman, J.; Kaasbjerg, K.; Oreg, Y.; von Oppen, F.; Ilani, S.
2016-07-01
One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed ‘excitonic’, promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the ‘glue’ that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.
Coulomb gauge model for hidden charm tetraquarks
Xie, W.; Mo, L. Q.; Wang, Ping; Cotanch, Stephen R.
2013-08-01
The spectrum of tetraquark states with hidden charm is studied within an effective Coulomb gauge Hamiltonian approach. Of the four independent color schemes, two are investigated, the (qcbar)1(cqbar)1 singlet-singlet (molecule) and the (qc)3(qbarcbar)3 triplet-triplet (diquark), for selected JPC states using a variational method. The predicted masses of triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet states. There is also an interesting flavor dependence with (qqbar)1 (ccbar1) states about half a GeV lighter than (qcbar)1(qbarc)1. The lightest 1++ and 1-- predictions are in agreement with the observed X (3872) and Y (4008) masses suggesting they are molecules with ωJ / ψ and ηhc, rather than D*Dbar* and DDbar, type structure, respectively. Similarly, the lightest isovector 1++ molecule, having a ρJ / ψ flavor composition, has mass near the recently observed charged Zc (3900) value. These flavor configurations are consistent with observed X, Y and Zc decays to ππJ / ψ.
Ultrafast state detection and 2D ion crystals in a Paul trap
Ip, Michael; Ransford, Anthony; Campbell, Wesley
2016-05-01
Projective readout of quantum information stored in atomic qubits typically uses state-dependent CW laser-induced fluorescence. This method requires an often sophisticated imaging system to spatially filter out the background CW laser light. We present an alternative approach that instead uses simple pulse sequences from a mode-locked laser to affect the same state-dependent excitations in less than 1 ns. The resulting atomic fluorescence occurs in the dark, allowing the placement of non-imaging detectors right next to the atom to improve the qubit state detection efficiency and speed. We also study 2D Coulomb crystals of atomic ions in an oblate Paul trap. We find that crystals with hundreds of ions can be held in the trap, potentially offering an alternative to the use of Penning traps for the quantum simulation of 2D lattice spin models. We discuss the classical physics of these crystals and the metastable states that are supported in 2D. This work is supported by the US Army Research Office.
Remarks on thermalization in 2D CFT
de Boer, Jan; Engelhardt, Dalit
2016-12-01
We revisit certain aspects of thermalization in 2D conformal field theory (CFT). In particular, we consider similarities and differences between the time dependence of correlation functions in various states in rational and non-rational CFTs. We also consider the distinction between global and local thermalization and explain how states obtained by acting with a diffeomorphism on the ground state can appear locally thermal, and we review why the time-dependent expectation value of the energy-momentum tensor is generally a poor diagnostic of global thermalization. Since all 2D CFTs have an infinite set of commuting conserved charges, generic initial states might be expected to give rise to a generalized Gibbs ensemble rather than a pure thermal ensemble at late times. We construct the holographic dual of the generalized Gibbs ensemble and show that, to leading order, it is still described by a Banados-Teitelboim-Zanelli black hole. The extra conserved charges, while rendering c <1 theories essentially integrable, therefore seem to have little effect on large-c conformal field theories.
Yang, Shengxue; Jiang, Chengbao; Wei, Su-huai
2017-06-01
Two-dimensional (2D) layered inorganic nanomaterials have attracted huge attention due to their unique electronic structures, as well as extraordinary physical and chemical properties for use in electronics, optoelectronics, spintronics, catalysts, energy generation and storage, and chemical sensors. Graphene and related layered inorganic analogues have shown great potential for gas-sensing applications because of their large specific surface areas and strong surface activities. This review aims to discuss the latest advancements in the 2D layered inorganic materials for gas sensors. We first elaborate the gas-sensing mechanisms and introduce various types of gas-sensing devices. Then, we describe the basic parameters and influence factors of the gas sensors to further enhance their performance. Moreover, we systematically present the current gas-sensing applications based on graphene, graphene oxide (GO), reduced graphene oxide (rGO), functionalized GO or rGO, transition metal dichalcogenides, layered III-VI semiconductors, layered metal oxides, phosphorene, hexagonal boron nitride, etc. Finally, we conclude the future prospects of these layered inorganic materials in gas-sensing applications.
Comments on Thermalization in 2D CFT
de Boer, Jan
2016-01-01
We revisit certain aspects of thermalization in 2D CFT. In particular, we consider similarities and differences between the time dependence of correlation functions in various states in rational and non-rational CFTs. We also consider the distinction between global and local thermalization and explain how states obtained by acting with a diffeomorphism on the ground state can appear locally thermal, and we review why the time-dependent expectation value of the energy-momentum tensor is generally a poor diagnostic of global thermalization. Since all 2D CFTs have an infinite set of commuting conserved charges, generic initial states might be expected to give rise to a generalized Gibbs ensemble rather than a pure thermal ensemble at late times. We construct the holographic dual of the generalized Gibbs ensemble and show that, to leading order, it is still described by a BTZ black hole. The extra conserved charges, while rendering $c < 1$ theories essentially integrable, therefore seem to have little effect o...
WFR-2D: an analytical model for PWAS-generated 2D ultrasonic guided wave propagation
Shen, Yanfeng; Giurgiutiu, Victor
2014-03-01
This paper presents WaveFormRevealer 2-D (WFR-2D), an analytical predictive tool for the simulation of 2-D ultrasonic guided wave propagation and interaction with damage. The design of structural health monitoring (SHM) systems and self-aware smart structures requires the exploration of a wide range of parameters to achieve best detection and quantification of certain types of damage. Such need for parameter exploration on sensor dimension, location, guided wave characteristics (mode type, frequency, wavelength, etc.) can be best satisfied with analytical models which are fast and efficient. The analytical model was constructed based on the exact 2-D Lamb wave solution using Bessel and Hankel functions. Damage effects were inserted in the model by considering the damage as a secondary wave source with complex-valued directivity scattering coefficients containing both amplitude and phase information from wave-damage interaction. The analytical procedure was coded with MATLAB, and a predictive simulation tool called WaveFormRevealer 2-D was developed. The wave-damage interaction coefficients (WDICs) were extracted from harmonic analysis of local finite element model (FEM) with artificial non-reflective boundaries (NRB). The WFR-2D analytical simulation results were compared and verified with full scale multiphysics finite element models and experiments with scanning laser vibrometer. First, Lamb wave propagation in a pristine aluminum plate was simulated with WFR-2D, compared with finite element results, and verified by experiments. Then, an inhomogeneity was machined into the plate to represent damage. Analytical modeling was carried out, and verified by finite element simulation and experiments. This paper finishes with conclusions and suggestions for future work.
About the role of 2D screening in high temperature superconductivity
Energy Technology Data Exchange (ETDEWEB)
Vazquez-Ponce, Yosdanis [Group of Theoretical Physics, Instituto de Cibernetica, Matematica y Fisica, Calle E, No. 309, Vedado, Havana (Cuba)]. E-mail: yvponce@gmail.com; Aguero, David Oliva [Group of Theoretical Physics, Instituto de Cibernetica, Matematica y Fisica, Calle E, No. 309, Vedado, Havana (Cuba)]. E-mail: david@cidet.icmf.inf.cu; Cabo Montes de Oca, Alejandro [International Centre for Theoretical Physics, Strada Costiera 11-34014, Miramare, Trieste (Italy)]. E-mail: cabo@cidet.icmf.inf.cu
2006-04-24
The 2D screening is investigated in a simple single band square tight-binding model which qualitatively resembles the known electronic structure in high temperature superconductors. The Coulomb kernel for the two particle Bethe-Salpeter equation in the single loop (RPA) approximation for the polarization can be evaluated in a strong tight-binding limit. The results indicate an intense screening of the Coulomb repulsion between the particles, which becomes stronger and anisotropic when the Fermi level approaches half filling (or, equivalently, when the Fermi surface turns to be near the Van Hove singularities) and rapidly decreases away from it. The effect is also more pronounced for quasi-momenta regions near the corners of the Brillouin cell, which corresponds to dual spatial distances of the order of a few unit cells. Therefore, a possible mechanism is identified which could explain the existence of extremely small Cooper pairs in these materials, as bounded anisotropic composite particles joined by residual super-exchange or phonon interactions.
Modelos exactamente solubles en mecanica estadistica de sistemas de Coulomb
National Research Council Canada - National Science Library
Tellez, Gabriel
2013-01-01
Se presenta una revision de modelos exactamente solubles de fisica estadistica clasica en dos dimensiones de sistemas de Coulomb, que son sistemas compuestos por un gran numero de particulas cargadas electricamente...
The generalized Coulomb interactions for relativistic scalar bosons
Zarrinkamar, S.; Panahi, H.; Rezaei, M.
2016-07-01
Approximate analytical solutions of Duffin-Kemmer-Petiau (DKP) equation are obtained for the truncated Coulomb, generalized Cornell, Richardson and Song-Lin potentials via the quasi-exact analytical ansatz approach.
Thermodynamic properties of the magnetized Coulomb crystal lattices
Kozhberov, A. A.
2016-08-01
It is thought that Coulomb crystals of ions with hexagonal close-packed lattice may form in the crust of strongly-magnetized neutron stars (magnetars). In this work we are trying to verify this prediction assuming that the direction of the magnetic field corresponds to the minimum of the zero-point energy. We also continue a detailed study of vibration modes and thermodynamic properties of magnetized Coulomb crystals in a wide range of temperatures and magnetic fields. It is demonstrated that the total Helmholtz free energy of the body-centered cubic Coulomb crystal is always lower than that of the Coulomb crystal with hexagonal close-packed or face-centered cubic lattice, which casts doubt on the hypothesis above.
Spin-spin interaction effect in 2D Extended Hubbard Model
Zouhair, A.; Harir, S.; Bennai, M.; Boughaleb, Y.
2014-09-01
Using an exact diagonlization for finite square lattice and taking into account the periodic boundary conditions in the two directions, we study the spin-spin interaction effect on some local electronic properties for antiferromagnetic correlated electrons system. We have considered an Extended Hubbard Model (EHM) including on-site coulomb interaction energy U and spin-spin interaction term J. The diagonlization of this 2D EHM model allows us to study J effect on some local properties for finite square lattice. The analysis of the obtained results shows that the introduction of spin-spin interaction induces a supplementary conductivity for antiferromagnetic correlated electrons system, even in the strong on-site interaction regime.
Simple field theoretical approach of Coulomb systems. Entropic effects
Energy Technology Data Exchange (ETDEWEB)
Di Caprio, D; Badiali, J P [Laboratory of Electrochemistry and Analytical Chemistry, University Paris 6, CNRS, ENSCP, BP 39, 4, Place Jussieu, 75252 Paris, Cedex 05 (France); Holovko, M [Institute for Condensed Matter Physics, National Academy of Sciences, 1 Svientsitskii Str, 79011 Lviv (Ukraine)], E-mail: dung.di_caprio@upmc.fr
2009-05-29
We discuss a new simple field theory approach of Coulomb systems. Using a description in terms of fields, we introduce in a new way the statistical degrees of freedom in relation to the quantum mechanics. We show by a series of examples that these fundamental entropic effects can help account for physical phenomena in relation to Coulomb systems whether symmetric or asymmetric in valence. Overall, this gives a new understanding of these systems.
COULOMB BLOCKADE OSCILLATIONS OF Si SINGLE-ELECTRON TRANSISTORS
Institute of Scientific and Technical Information of China (English)
王太宏; 李宏伟; 周均铭
2001-01-01
Coulomb blockade oscillations of Si single-electron transistors, which are fabricated completely by the conventional photolithography technique, have been investigated. Most of the single-electron transistors clearly show Coulomb blockade oscillations and these oscillations can be periodic by applying negative voltages to the in-plane gates. A shift of the peak positions is observed at high temperatures. It is also found that the fluctuation of the peak spacing cannot be neglected.
2-D Model Test of Dolosse Breakwater
DEFF Research Database (Denmark)
Burcharth, Hans F.; Liu, Zhou
1994-01-01
The rational design diagram for Dolos armour should incorporate both the hydraulic stability and the structural integrity. The previous tests performed by Aalborg University (AU) made available such design diagram for the trunk of Dolos breakwater without superstructures (Burcharth et al. 1992......). To extend the design diagram to cover Dolos breakwaters with superstructure, 2-D model tests of Dolos breakwater with wave wall is included in the project Rubble Mound Breakwater Failure Modes sponsored by the Directorate General XII of the Commission of the European Communities under Contract MAS-CT92...... was on the Dolos breakwater with a high superstructure, where there was almost no overtopping. This case is believed to be the most dangerous one. The test of the Dolos breakwater with a low superstructure was also performed. The objective of the last part of the experiment is to investigate the influence...
Alignment free characterization of 2D gratings
Madsen, Morten Hannibal; Hansen, Poul-Erik; Jørgensen, Jan Friis
2015-01-01
Fast characterization of 2-dimensional gratings is demonstrated using a Fourier lens optical system and a differential optimization algorithm. It is shown that both the grating specific parameters such as the basis vectors and the angle between them and the alignment of the sample, such as the rotation of the sample around the x-, y-, and z-axis, can be deduced from a single measurement. More specifically, the lattice vectors and the angle between them have been measured, while the corrections of the alignment parameters are used to improve the quality of the measurement, and hence reduce the measurement uncertainty. Alignment free characterization is demonstrated on both a 2D hexagonal grating with a period of 700 nm and a checkerboard grating with a pitch of 3000 nm. The method can also be used for both automatic alignment and in-line characterization of gratings.
2D Cooling of Magnetized Neutron Stars
Aguilera, Deborah N; Miralles, Juan A
2007-01-01
Context: Many thermally emitting isolated neutron stars have magnetic fields larger than 10^{13}G. A realistic cooling model should be reconsidered including the presence of high magnetic fields. Aims: We investigate the effects of anisotropic temperature distribution and Joule heating on the cooling of magnetized neutron stars. Methods: The 2D heat transfer equation with anisotropic thermal conductivity tensor and including all relevant neutrino emission processes is solved for realistic models of the neutron star interior and crust. Results: The presence of the magnetic field affects significantly the thermal surface distribution and the cooling history during both, the early neutrino cooling era and the late photon cooling era. Conclusions: There is a huge effect of the Joule heating on the thermal evolution of strongly magnetized neutron stars. Magnetic fields and Joule heating play a key role in maintaining magnetars warm for a long time. Moreover, this effect is also important for intermediate field neu...
Lie symmetries and 2D Material Physics
Belhaj, Adil
2014-01-01
Inspired from Lie symmetry classification, we establish a correspondence between rank two Lie symmetries and 2D material physics. The material unit cell is accordingly interpreted as the geometry of a root system. The hexagonal cells, appearing in graphene like models, are analyzed in some details and are found to be associated with A_2 and G_2 Lie symmetries. This approach can be applied to Lie supersymmetries associated with fermionic degrees of freedom. It has been suggested that these extended symmetries can offer a new way to deal with doping material geometries. Motivated by Lie symmetry applications in high energy physics, we speculate on a possible connection with (p,q) brane networks used in the string theory compactification on singular Calabi-Yau manifolds.
2-d Simulations of Test Methods
DEFF Research Database (Denmark)
Thrane, Lars Nyholm
2004-01-01
approach is presented by showing initial results from 2-d simulations of the empirical test methods slump flow and L-box. This method assumes a homogeneous material, which is expected to correspond to particle suspensions e.g. concrete, when it remains stable. The simulations have been carried out when......One of the main obstacles for the further development of self-compacting concrete is to relate the fresh concrete properties to the form filling ability. Therefore, simulation of the form filling ability will provide a powerful tool in obtaining this goal. In this paper, a continuum mechanical...... using both a Newton and Bingham model for characterisation of the rheological properties of the concrete. From the results, it is expected that both the slump flow and L-box can be simulated quite accurately when the model is extended to 3-d and the concrete is characterised according to the Bingham...
Full revivals in 2D quantum walks
Energy Technology Data Exchange (ETDEWEB)
Stefanak, M; Jex, I [Department of Physics, FJFI CVUT v Praze, Brehova 7, 115 19 Praha 1-Stare Mesto (Czech Republic); Kollar, B; Kiss, T, E-mail: martin.stefanak@fjfi.cvut.c [Department of Quantum Optics and Quantum Information, Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Konkoly-Thege M. u. 29-33, H-1121 Budapest (Hungary)
2010-09-01
Recurrence of a random walk is described by the Polya number. For quantum walks, recurrence is understood as the return of the walker to the origin, rather than the full revival of its quantum state. Localization for two-dimensional quantum walks is known to exist in the sense of non-vanishing probability distribution in the asymptotic limit. We show, on the example of the 2D Grover walk, that one can exploit the effect of localization to construct stationary solutions. Moreover, we find full revivals of a quantum state with a period of two steps. We prove that there cannot be longer cycles for a four-state quantum walk. Stationary states and revivals result from interference, which has no counterpart in classical random walks.
2-D Model Test of Dolosse Breakwater
DEFF Research Database (Denmark)
Burcharth, Hans F.; Liu, Zhou
1994-01-01
The rational design diagram for Dolos armour should incorporate both the hydraulic stability and the structural integrity. The previous tests performed by Aalborg University (AU) made available such design diagram for the trunk of Dolos breakwater without superstructures (Burcharth et al. 1992......). To extend the design diagram to cover Dolos breakwaters with superstructure, 2-D model tests of Dolos breakwater with wave wall is included in the project Rubble Mound Breakwater Failure Modes sponsored by the Directorate General XII of the Commission of the European Communities under Contract MAS-CT92......-0042. Furthermore, Task IA will give the design diagram for Tetrapod breakwaters without a superstructure. The more complete research results on Dolosse can certainly give some insight into the behaviour of Tetrapods armour layer of the breakwaters with superstructure. The main part of the experiment...
2D Electrostatic Actuation of Microshutter Arrays
Burns, Devin E.; Oh, Lance H.; Li, Mary J.; Jones, Justin S.; Kelly, Daniel P.; Zheng, Yun; Kutyrev, Alexander S.; Moseley, Samuel H.
2015-01-01
An electrostatically actuated microshutter array consisting of rotational microshutters (shutters that rotate about a torsion bar) were designed and fabricated through the use of models and experiments. Design iterations focused on minimizing the torsional stiffness of the microshutters, while maintaining their structural integrity. Mechanical and electromechanical test systems were constructed to measure the static and dynamic behavior of the microshutters. The torsional stiffness was reduced by a factor of four over initial designs without sacrificing durability. Analysis of the resonant behavior of the microshutter arrays demonstrates that the first resonant mode is a torsional mode occurring around 3000 Hz. At low vacuum pressures, this resonant mode can be used to significantly reduce the drive voltage necessary for actuation requiring as little as 25V. 2D electrostatic latching and addressing was demonstrated using both a resonant and pulsed addressing scheme.
Coulomb sink effect on coarsening of metal nanostructures on surfaces
Institute of Scientific and Technical Information of China (English)
Yong HAN; Feng LIU
2008-01-01
We discuss Coulomb effects on the coarsening of metal nanostructures on surfaces. We have proposed a new concept of a "Coulomb sink" [Phys. Rev. Lett., 2004, 93: 106102] to elucidate the effect of Coulomb charging on the coarsening of metal mesas grown on semiconductor surfaces. A charged mesa, due to its reduced chemical potential, acts as a Coulomb sink and grows at the expense of neighboring neu-tral mesas. The Coulomb sink provides a potentially useful method for the controlled fabrication of metal nanostructures. In this article, we will describe in detail the proposed physical models, which can explain qualitatively the most salient fea-tures of coarsening of charged Pb mesas on the Si(111) sur-face, as observed by scanning tunneling microscopy (STM). We will also describe a method of precisely fabricating large-scale nanocrystals with well-defined shape and size. By using the Coulomb sink effect, the artificial center-full-hol-lowed or half-hollowed nanowells can be created.
Stacked charge stripes in the quasi-2D trilayer nickelate La4Ni3O8
Zhang, Junjie; Chen, Yu-Sheng; Phelan, D.; Zheng, Hong; Norman, M. R.; Mitchell, J. F.
2016-08-01
The quasi-2D nickelate La4Ni3O8 (La-438), consisting of trilayer networks of square planar Ni ions, is a member of the so-called T' family, which is derived from the Ruddlesden-Popper (R-P) parent compound La4Ni3O10-x by removing two oxygen atoms and rearranging the rock salt layers to fluorite-type layers. Although previous studies on polycrystalline samples have identified a 105-K phase transition with a pronounced electronic and magnetic response but weak lattice character, no consensus on the origin of this transition has been reached. Here, we show using synchrotron X-ray diffraction on high-pO2 floating zone-grown single crystals that this transition is associated with a real space ordering of charge into a quasi-2D charge stripe ground state. The charge stripe superlattice propagation vector, q = (2/3, 0, 1), corresponds with that found in the related 1/3-hole doped single-layer R-P nickelate, La5/3Sr1/3NiO4 (LSNO-1/3; Ni2.33+), with orientation at 45° to the Ni-O bonds. The charge stripes in La-438 are weakly correlated along c to form a staggered ABAB stacking that reduces the Coulomb repulsion among the stripes. Surprisingly, however, we find that the charge stripes within each trilayer of La-438 are stacked in phase from one layer to the next, at odds with any simple Coulomb repulsion argument.
Fast 2-D Complex Gabor Filter with Kernel Decomposition
Um, Suhyuk; Kim, Jaeyoon; Min, Dongbo
2017-01-01
2-D complex Gabor filtering has found numerous applications in the fields of computer vision and image processing. Especially, in some applications, it is often needed to compute 2-D complex Gabor filter bank consisting of the 2-D complex Gabor filtering outputs at multiple orientations and frequencies. Although several approaches for fast 2-D complex Gabor filtering have been proposed, they primarily focus on reducing the runtime of performing the 2-D complex Gabor filtering once at specific...
Scale-free avalanches in disordered systems of localized charges with long-range Coulomb interaction
Palassini, Matteo; Goethe, Martin
2012-02-01
We study theoretically and numerically the charge avalanches created by a perturbation in disordered systems of localized charges with unscreened Coulomb interaction (the so-called electron glass model), in two and three dimensions. Starting from a low-lying local energy minimum, we perturb the system by inserting an extra charge or an extra dipole, and let it relax via one-particle hops until a new minimum is reached. We find that the size distribution of the avalanches created in this process displays generically a power-law tail with an exponent close to the mean-field value 3/2 both in 2D and 3D, without requiring any parameter tuning. We provide a qualitative explanation of these results in terms of the density of states of elementary charge and dipole excitations and the associated Coulomb gap, which shows that the power-law tail arises from arbitrarily long hops, without requiring to assume the existence of a glass phase. Finally, we discuss the experimental relevance of these results and compare our picture to similar scale-free avalanches observed in mean field spin glasses, in which they are are associated to a marginal glass phase.
Amplitude Function of Asymptotic Correlations Along Charged Wall in Coulomb Fluids
Šamaj, Ladislav
2016-07-01
In classical semi-infinite Coulomb fluids, two-point correlation functions exhibit a slow inverse-power law decay along a uniformly charged wall. In this work, we concentrate on the corresponding amplitude function which depends on the distances of the two points from the wall. Recently Šamaj (J Stat Phys 161:227-249 2015), applying a technique of anticommuting variables to a 2D system of charged rectilinear wall with "counter-ions only", we derived a relation between the amplitude function and the density profile which holds for any temperature. In this paper, using the Möbius conformal transformation of particle coordinates in a disc, a new relation between the amplitude function and the density profile is found for that model. In all exactly solvable cases, the amplitude function factorizes itself in the two distances from the wall. Presupposing this factorization property at any temperature and using specific sum rules for semi-infinite geometries, a relation between the amplitude function of the charge-charge structure function and the charge profile is derived for many-component Coulomb fluids in any dimension.
Metrology for graphene and 2D materials
Pollard, Andrew J.
2016-09-01
The application of graphene, a one atom-thick honeycomb lattice of carbon atoms with superlative properties, such as electrical conductivity, thermal conductivity and strength, has already shown that it can be used to benefit metrology itself as a new quantum standard for resistance. However, there are many application areas where graphene and other 2D materials, such as molybdenum disulphide (MoS2) and hexagonal boron nitride (h-BN), may be disruptive, areas such as flexible electronics, nanocomposites, sensing and energy storage. Applying metrology to the area of graphene is now critical to enable the new, emerging global graphene commercial world and bridge the gap between academia and industry. Measurement capabilities and expertise in a wide range of scientific areas are required to address this challenge. The combined and complementary approach of varied characterisation methods for structural, chemical, electrical and other properties, will allow the real-world issues of commercialising graphene and other 2D materials to be addressed. Here, examples of metrology challenges that have been overcome through a multi-technique or new approach are discussed. Firstly, the structural characterisation of defects in both graphene and MoS2 via Raman spectroscopy is described, and how nanoscale mapping of vacancy defects in graphene is also possible using tip-enhanced Raman spectroscopy (TERS). Furthermore, the chemical characterisation and removal of polymer residue on chemical vapour deposition (CVD) grown graphene via secondary ion mass spectrometry (SIMS) is detailed, as well as the chemical characterisation of iron films used to grow large domain single-layer h-BN through CVD growth, revealing how contamination of the substrate itself plays a role in the resulting h-BN layer. In addition, the role of international standardisation in this area is described, outlining the current work ongoing in both the International Organization of Standardization (ISO) and the
Abdelmadjid Maireche
2016-01-01
A novel theoretical study for the exact solvability of nonrelativistic quantum spectrum systems for potential containing coulomb and quadratic terms is discussed used both Boopp’s shift method and standard perturbation theory in both noncommutativity two dimensional real space and phase (NC-2D: RSP), it has been observed that the exact corrections for the ground states spectrum of studied potential was depended on two infinitesimals parameters and which plays an opposite rolls, and we ha...
Analysis of a Fully Packed Loop Model Arising in a Magnetic Coulomb Phase
Jaubert, L. D. C.; Haque, M.; Moessner, R.
2011-10-01
The Coulomb phase of spin ice, and indeed the Ic phase of water ice, naturally realize a fully packed two-color loop model in 3D. We present a detailed analysis of the statistics of these loops: we find loops spanning the system multiple times hosting a finite fraction of all sites while the average loop length remains finite. We contrast the behavior with an analogous 2D model. We connect this body of results to properties of polymers, percolation and insights from Schramm-Loewner evolution processes. We also study another extended degree of freedom, called worms, which appear as “Dirac strings” in spin ice. We discuss implications of these results for the efficiency of numerical cluster algorithms, and address implications for the ordering properties of a broader class of magnetic systems, e.g., with Heisenberg spins, such as CsNiCrF6 or ZnCr2O4.
|m| Partial wave treatment for two-dimensional Coulomb-scattering and Regge pole
Institute of Scientific and Technical Information of China (English)
WANG; Jing; ZENG; Jinyan
2004-01-01
The symmetry and |m| partial-wave analysis for two-dimensional (2D) Coulomb-scattering is investigated. As a function of energy E, the |m| partial-wave scattering amplitude f|m|(θ) is analytically continuated to the negative E (complex k) plane, and it is found that the bound state energy eigenvalues (E<0) are just located at the poles of f|m|(θ) on the positive imaginary k axis as is expected. In addition, as a function of |m|, f|m|(θ) is analytically continuated to the complex |m| plane, the bound state energy eigenvalues are just located at the poles of f|m|(θ) on the positive real |m| axis.
Coulomb-driven energy boost of heavy ions for laser-plasma acceleration.
Braenzel, J; Andreev, A A; Platonov, K; Klingsporn, M; Ehrentraut, L; Sandner, W; Schnürer, M
2015-03-27
An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultrathin gold foils have been irradiated by an ultrashort laser pulse at a peak intensity of 8×10^{19} W/ cm^{2}. Highly charged gold ions with kinetic energies up to >200 MeV and a bandwidth limited energy distribution have been reached by using 1.3 J laser energy on target. 1D and 2D particle in cell simulations show how a spatial dependence on the ion's ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a spatial distribution of the ionization inside the thin target, leading to a field enhancement for the heavy ions by Coulomb explosion. It is capable of explaining the energy boost of highly charged ions, enabling a higher efficiency for the laser-driven heavy ion acceleration.
Hirobe, Tomohisa; Ito, Shosuke; Wakamatsu, Kazumasa
2013-09-01
The novel mutation named ru2(d) /Hps5(ru2-d) , characterized by light-colored coats and ruby-eyes, prohibits differentiation of melanocytes by inhibiting tyrosinase (Tyr) activity, expression of Tyr, Tyr-related protein 1 (Tyrp1), Tyrp2, and Kit. However, it is not known whether the ru2(d) allele affects pheomelanin synthesis in recessive yellow (e/Mc1r(e) ) or in pheomelanic stage in agouti (A) mice. In this study, effects of the ru2(d) allele on pheomelanin synthesis were investigated by chemical analysis of melanin present in dorsal hairs of 5-week-old mice from F2 generation between C57BL/10JHir (B10)-co-isogenic ruby-eye 2(d) and B10-congenic recessive yellow or agouti. Eumelanin content was decreased in ruby-eye 2(d) and ruby-eye 2(d) agouti mice, whereas pheomelanin content in ruby-eye 2(d) recessive yellow and ruby-eye 2(d) agouti mice did not differ from the corresponding Ru2(d) /- mice, suggesting that the ru2(d) allele inhibits eumelanin but not pheomelanin synthesis. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Analysis of the IEA 2D test. 2D, 3D, steady or unsteady airflow?
DEFF Research Database (Denmark)
Cortes, Ines Olmedo; Nielsen, Peter V.
The “IEA Annex 20 two-dimensional test case” was defined by proffesor Peter V. Nielsen (1990) and was originally considered two-dimensional and steady flow. However, some recent works considering the case as three dimensional have shown different solutions from the 2D case as well as different so...
Stable and Critical Noncohesive Coulomb Wedges: Exact Elastic Solutions
Wang, K.; Hu, Y.
2004-12-01
The theory of critically tapered Coulomb wedge has been successfully applied to model active fold-and-thrust belts or submarine accretionary prisms. Brittle mountain building is episodic in nature, controlled by changes in basal friction, erosion and sedimentation, and hydrogeology. Sediment accretion may be modulated by great subduction earthquakes. Between deformation episodes and/or during transition between compressional and extensional tectonics, the Coulomb wedges are stable (i.e., supercritical), to which the critical taper theory does not apply. In this work, we provide an exact elastic solution for stable wedges based on Airy stress functions. The stress equilibrium equation and definition of basal friction and basal and internal pore fluid pressure ratios are exactly the same as those used for Dahlen's [1984] exact solution for critical noncohesive Coulomb wedges, but internal friction μ becomes irrelevant. Given elastic - perfectly Coulomb-plastic rheology, for stresses in a wedge on the verge of Coulomb failure there must co-exist a critical taper solution involving μ and a unique equivalent elastic solution not involving μ . Our elastic solution precisely reduces to Dahlen's critical taper solution for critical conditions. For stable conditions, normal stress perpendicular to the surface slope σ z and shear stress τ xz are identical with those in a critical taper, but the slope-parallel normal stress is different. The elastic solution is also generally applicable to purely elastic wedges and useful for modeling geodetic observations. A stable noncohesive Coulomb wedge differs from a general elastic wedge in that its upper and lower surfaces stay at zero curvature during loading. Dahlen, F.A. (1984), Noncohesive critical Coulomb wedges: An exact solution, JGR, 89, 10,125-10,133.
Conforming the measured lifetimes of the $5d \\ ^2D_{3/2,5/2}$ states in Cs with theory
Sahoo, B K
2015-01-01
We find very good agreement between our theoretically evaluated lifetimes of the $5d \\ ^2D_{3/2}$ and $5d \\ ^2D_{5/2}$ states of Cs with the experimental values reported in [Phys. Rev. A {\\bf 57}, 4204 (1998)], which were earlier evinced to be disagreeing with an earlier rigorous theoretical study [Phys. Rev. A {\\bf 69}, 040501(R) (2004)] and with another precise measurement [Opt. Lett. {\\bf 21}, 74 (1996)]. In this work, we have carried out calculations of the radiative transition matrix elements using many variants of relativistic many-body methods, mainly in the coupled-cluster theory framework, and analyze propagation of the electron correlation effects to elucidate their roles for accurate evaluations of the matrix elements. We also demonstrate contributions explicitly from the Dirac-Coulomb interactions, frequency independent Breit interaction and lower order quantum electrodynamics (QED) effects. Uncertainties to these matrix elements due to different possible sources of errors are estimated. By combin...
Analysis list: Kmt2d [Chip-atlas[Archive
Lifescience Database Archive (English)
Full Text Available Kmt2d Adipocyte,Pluripotent stem cell + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Kmt2d....1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Kmt2d.5.tsv http://dbarchiv...e.biosciencedbc.jp/kyushu-u/mm9/target/Kmt2d.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Kmt2d....Adipocyte.tsv,http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Kmt2d.Pluripo
Intermittency in 2D soap film turbulence
Cerbus, R T
2013-01-01
The Reynolds number dependency of intermittency for 2D turbulence is studied in a flowing soap film. The Reynolds number used here is the Taylor microscale Reynolds number R_{\\lambda}, which ranges from 20 to 800. Strong intermittency is found for both the inverse energy and direct enstrophy cascades as measured by (a) the pdf of velocity differences P(\\delta u(r)) at inertial scales r, (b) the kurtosis of P(\\partial_x u), and (c) the scaling of the so-called intermittency exponent \\mu, which is zero if intermittency is absent. Measures (b) and (c) are quantitative, while (a) is qualitative. These measurements are in disagreement with some previous results but not all. The velocity derivatives are nongaussian at all R_{\\lambda} but show signs of becoming gaussian as R_{\\lambda} increases beyond the largest values that could be reached. The kurtosis of P(\\delta u(r)) at various r indicates that the intermittency is scale dependent. The structure function scaling exponents also deviate strongly from the Kraichn...
Competing coexisting phases in 2D water
Zanotti, Jean-Marc; Judeinstein, Patrick; Dalla-Bernardina, Simona; Creff, Gaëlle; Brubach, Jean-Blaise; Roy, Pascale; Bonetti, Marco; Ollivier, Jacques; Sakellariou, Dimitrios; Bellissent-Funel, Marie-Claire
2016-05-01
The properties of bulk water come from a delicate balance of interactions on length scales encompassing several orders of magnitudes: i) the Hydrogen Bond (HBond) at the molecular scale and ii) the extension of this HBond network up to the macroscopic level. Here, we address the physics of water when the three dimensional extension of the HBond network is frustrated, so that the water molecules are forced to organize in only two dimensions. We account for the large scale fluctuating HBond network by an analytical mean-field percolation model. This approach provides a coherent interpretation of the different events experimentally (calorimetry, neutron, NMR, near and far infra-red spectroscopies) detected in interfacial water at 160, 220 and 250 K. Starting from an amorphous state of water at low temperature, these transitions are respectively interpreted as the onset of creation of transient low density patches of 4-HBonded molecules at 160 K, the percolation of these domains at 220 K and finally the total invasion of the surface by them at 250 K. The source of this surprising behaviour in 2D is the frustration of the natural bulk tetrahedral local geometry and the underlying very significant increase in entropy of the interfacial water molecules.
Ion Transport in 2-D Graphene Nanochannels
Xie, Quan; Foo, Elbert; Duan, Chuanhua
2015-11-01
Graphene membranes have recently attracted wide attention due to its great potential in water desalination and selective molecular sieving. Further developments of these membranes, including enhancing their mass transport rate and/or molecular selectivity, rely on the understanding of fundamental transport mechanisms through graphene membranes, which has not been studied experimentally before due to fabrication and measurement difficulties. Herein we report the fabrication of the basic constituent of graphene membranes, i.e. 2-D single graphene nanochannels (GNCs) and the study of ion transport in these channels. A modified bonding technique was developed to form GNCs with well-defined geometry and uniform channel height. Ion transport in such GNCs was studied using DC conductance measurement. Our preliminary results showed that the ion transport in GNCs is still governed by surface charge at low concentrations (10-6M to 10-4M). However, GNCs exhibits much higher ionic conductances than silica nanochannels with the same geometries in the surface-charge-governed regime. This conductance enhancement can be attributed to the pre-accumulation of charges on graphene surfaces. The work is supported by the Faculty Startup Fund (Boston University, USA).
2D DIGITAL SIMPLIFIED FLOW VALVE
Institute of Scientific and Technical Information of China (English)
Ruan Jian; Li Sheng; Pei Xiang; Burton R; Ukrainetz P; Bitner D
2004-01-01
The 2D digital simplified flow valve is composed of a pilot-operated valve designed with both rotary and linear motions of a single spool,and a stepper motor under continual control.How the structural parameters affect the static and dynamic characteristics of the valve is first clarified and a criterion for stability is presented.Experiments are designed to test the performance of the valve.It is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters.Nevertheless,it is possible to maintain the dynamic response at a fairly high level,while keeping the leakage of the pilot stage at an acceptable level.One of the features of the digital valve is stage control.In stage control the nonlinearities,such as electromagnetic saturation and hysteresis,are greatly reduced.To a large extent the dynamic response of the valve is decided by the executing cycle of the control algorithm.
Coulomb interaction in multiple scattering theory. [Kerman-McManus-Thaler and Watson theories
Energy Technology Data Exchange (ETDEWEB)
Ray, L.; Hoffmann, G.W.; Thaler, R.M.
1980-10-01
The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+/sup 208/Pb elastic scattering and compared with experimental data.
Energy Technology Data Exchange (ETDEWEB)
Djouder, M., E-mail: djouder-madjid@ummto.dz; Kermoun, F.; Mitiche, M. D.; Lamrous, O. [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri Tizi-Ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria)
2016-01-15
Dust particles observed in universe as well as in laboratory and technological plasma devices are still under investigation. At low temperature, these particles are strongly negatively charged and are able to form a 2D or 3D coulomb crystal. In this work, our aim was to check the ideal gas law validity for a 2D single-layer dust crystal recently reported in the literature. For this purpose, we have simulated, using the molecular dynamics method, its thermodynamic properties for different values of dust particles number and confinement parameters. The obtained results have allowed us to invalidate the ideal gas behaviour and to propose an effective equation of state which assumes a near zero dust temperature. Furthermore, the value of the calculated sound velocity was found to be in a good agreement with experimental data published elsewhere.
Coulomb and nuclear effects in breakup and reaction cross sections
Descouvemont, P.; Canto, L. F.; Hussein, M. S.
2017-01-01
We use a three-body continuum discretized coupled channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li+208Pb . For breakup, we investigate various aspects, such as the role of the α +t continuum, the angular-momentum distribution, and the balance between Coulomb and nuclear effects. We show that there is a large ambiguity in defining the Coulomb and nuclear breakup cross sections, since both techniques, although providing the same total breakup cross sections, strongly differ for the individual components. We suggest a third method which could be efficiently used to address convergence problems at large angular momentum. For reaction cross sections, interference effects are smaller, and the nuclear contribution is dominant above the Coulomb barrier. We also draw attention to different definitions of the reaction cross section which exist in the literature and which may induce small, but significant, differences in the numerical values.
2-D Animation's Not Just for Mickey Mouse.
Weinman, Lynda
1995-01-01
Discusses characteristics of two-dimensional (2-D) animation; highlights include character animation, painting issues, and motion graphics. Sidebars present Silicon Graphics animations tools and 2-D animation programs for the desktop computer. (DGM)
Efros-Shklovskii Coulomb gap in the absence of disorder
Rademaker, Louk; Mahmoudian, Samiyeh; Ralko, Arnaud; Fratini, Simone; Dobrosavljevic, Vladimir
2015-03-01
Certain models of frustrated electron systems have been shown to self-generate glassy behavior, in the absence of disorder. Possible candidate materials contain quarter-filled triangular lattices with long-range Coulomb interactions, as found in the θ-family of organic BEDT-TTF crystals. In disordered insulators with localized electronic states, the so-called Coulomb glass, the single particle excitation spectrum displays the well-known Efros-Shklovskii gap. The same excitation spectrum is investigated in a class of models that display self-generated electronic glassiness, showing pseudogap formation related to the Efros-Shklovskii Coulomb gap. Our study suggests universal characteristics of all electron glasses, regardless of disorder.
Elementary excitations and avalanches in the Coulomb glass
Palassini, Matteo; Goethe, Martin
2012-07-01
We study numerically the statistics of elementary excitations and charge avalanches in the classical Coulomb glass model of localized charges with unscreened Coulomb interaction and disorder. We compute the single-particle density of states with an energy minimization algorithm for systems of up to 1003 sites. The shape of the Coulomb gap is consistent with a power-law with exponent δ simeq 2.4 and marginally consistent with exponential behavior. The results are also compared with a recently proposed self-consistent approach. We then analyze the size distribution of the charge avalanches produced by a small perturbation of the system. We show that the distribution decays as a power law in the limit of large system size, and explain this behavior in terms of the elementary excitations. Similarities and differences with the scale-free avalanches observed in mean-field spin glasses are discussed.
Quasiparticle Gaps and Exciton Coulomb Energies in Si Nanoshells
Energy Technology Data Exchange (ETDEWEB)
Frey, K. [University of Illinois, Chicago; Idrobo Tapia, Juan C [ORNL; Tiago, Murilo L [ORNL; Reboredo, Fernando A [ORNL; Ogut, Serdar [University of Illinois, Chicago
2009-01-01
Quasiparticle gaps and exciton Coulomb energies of H-passivated spherical Si nanoshells are computed using rst principles SCF and GW methods. We nd that the quasiparticle gap of a nanoshell depends on both its inner radius R1 (weakly) and outer radius R2 (strongly). These dependences on R1 and R2 are mostly consistent with electrostatics of a metallic shell. We also nd that the unscreened Coulomb energy ECoul in Si nanoshells has a somewhat unexpected size dependence at xed outer radius R2: ECoul decreases as the nanoshell becomes more conning, contrary to what one would expect from quantum connement eects. We show that this is a consequence of an increase in the average electron-hole distance, giving rise to reduced exciton Coulomb energies in spite of the reduction in the conning nanoshell volume.
CubeSat testing of Coulomb drag propulsion
Janhunen, Pekka; Toivanen, Petri; Rauhala, Timo; Haeggström, Edward; Grönland, Tor-Arne
2016-01-01
In Coulomb drag propulsion, a long high voltage tether or system of tethers gathers momentum from a natural plasma stream such as solar wind or ionospheric plasma ram flow. A positively polarised tether in the solar wind can be used for efficient general-purpose interplanetary propellantless propulsion (the electric solar wind sail or E-sail), whereas a negatively polarised tether in LEO can be used for efficient deorbiting of satellites (the plasma brake). Aalto-1 is a 3-U cubesat to be launched in May 2016. The satellite carries three scientific experiments including 100 m long Coulomb drag tether experiment. The tether is made of four 25 and 50 micrometre diameter aluminium wires that are ultrasonically bonded together every few centimetre intervals. The tether can be charged by an onboard voltage source up to one kilovolt positive and negative. The Coulomb drag is measured by monitoring the spin rate.
Coulomb crystal mass spectrometry in a digital ion trap
Deb, Nabanita; Smith, Alexander D; Keller, Matthias; Rennick, Christopher J; Heazlewood, Brianna R; Softley, Timothy P
2015-01-01
We present a mass spectrometric technique for identifying the masses and relative abundances of Coulomb-crystallized ions held in a linear Paul trap. A digital radiofrequency waveform is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields subsequently applied to the trap electrodes for ion ejection. Excellent detection efficiency is demonstrated for Ca+ and CaF+ ions from bi-component Ca+/CaF+ Coulomb crystals prepared by reaction of Ca+ with CH3F. A quantitative linear relationship is observed between ion number and the corresponding integrated TOF peak, independent of the ionic species. The technique is applicable to a diverse range of multi-component Coulomb crystals - demonstrated here for Ca+/NH3+/NH4+ and Ca+/CaOH+/CaOD+ crystals - and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.
Gribov horizon and Gribov copies effect in lattice Coulomb gauge
Burgio, Giuseppe; Reinhardt, Hugo; Vogt, Hannes
2016-01-01
Following a recent proposal by Cooper and Zwanziger we investigate via lattice simulations the effect on the Coulomb gauge propagators and on the Gribov-Zwanziger confinement mechanism of selecting the Gribov copy with the smallest non-trivial eigenvalue of the Faddeev-Popov operator, i.e. the one closest to the Gribov horizon. Although such choice of gauge drives the ghost propagator towards the prediction of continuum calculations, we find that it actually overshoots the goal. With increasing computer time, we observe that Gribov copies with arbitrarily small eigenvalues can be found. For such a method to work one would therefore need further restrictions on the gauge condition to isolate the physically relevant copies, since e.g. the Coulomb potential $V_C$ defined through the Faddeev-Popov operator becomes otherwise physically meaningless. Interestingly, the Coulomb potential alternatively defined through temporal link correlators is only marginally affected by the smallness of the eigenvalues.
Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study
DEFF Research Database (Denmark)
Lunde, Anders Mathias; Flensborg, Karsten; Jauho, Antti-Pekka
2005-01-01
We calculate the intershell resistance R-21 in a multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F) (e.g., a gate voltage), varying the chirality of the inner and outer tubes. This is done in a so-called Coulomb drag setup, where a current I-1 in one shell induces...... effects for the Coulomb drag between different tubes due to selection rules combined with mismatching of wave vector and crystal angular momentum conservation near the Fermi level. This gives rise to orders of magnitude changes in R-21 and even the sign of R-21 can change depending on the chirality...
Spin and polarized current from Coulomb blockaded quantum dots.
Potok, R M; Folk, J A; Marcus, C M; Umansky, V; Hanson, M; Gossard, A C
2003-07-04
We report measurements of spin transitions for GaAs quantum dots in the Coulomb blockade regime and compare ground and excited state transport spectroscopy to direct measurements of the spin polarization of emitted current. Transport spectroscopy reveals both spin-increasing and spin-decreasing transitions, as well as higher-spin ground states, and allows g factors to be measured down to a single electron. The spin of emitted current in the Coulomb blockade regime, measured using spin-sensitive electron focusing, is found to be polarized along the direction of the applied magnetic field regardless of the ground state spin transition.
Correlated Coulomb drag in capacitively coupled quantum-dot structures
DEFF Research Database (Denmark)
Kaasbjerg, Kristen; Jauho, Antti-Pekka
2016-01-01
We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach which accounts for higher-order tunneling (cotunneling....... Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments...
An algebraic model of Coulomb scattering with spin
Energy Technology Data Exchange (ETDEWEB)
Levay, P. [School of Physics, University of Melbourne, Parkville (Australia); Department of Theoretical Physics, Institute of Physics, Technical University, Budapest (Hungary); Amos, K. [School of Physics, University of Melbourne, Parkville (Australia)
2001-05-11
A new matrix-valued realization for the so(3,1) algebra leads to a natural generalization of the Coulomb scattering problem of a particle with spin. The underlying su(2) gauge structure of this realization recasts the scattering problem into a familiar form, namely, the Coulomb scattering problem of a collection of dyons (particles having both electric and magnetic charges). Using this equivalent form and the results of Zwanziger for such systems, the scattering matrix can be calculated in the helicity formalism. (author)
Lyapunov spectra of Coulombic and gravitational periodic systems
Kumar, Pankaj
2016-01-01
We compute Lyapunov spectra for Coulombic and gravitational versions of the one-dimensional systems of parallel sheets with periodic boundary conditions. Exact time evolution of tangent-space vectors are derived and are utilized toward computing Lypaunov characteristic exponents using an event-driven algorithm. The results indicate that the energy dependence of the largest Lyapunov exponent emulates that of Kolmogorov-entropy density for each system at different degrees of freedom. Our approach forms an effective and approximation-free tool toward studying the dynamical properties exhibited by the Coulombic and gravitational systems and finds applications in investigating indications of thermodynamic transitions in large versions of the spatially periodic systems.
Vibrational motions in rotating nuclei studied by Coulomb excitations
Energy Technology Data Exchange (ETDEWEB)
Shimizu, Yoshifumi R. [Kyushu Univ., Fukuoka (Japan). Dept. of Physics
1998-03-01
As is well-known Coulomb excitation is an excellent tool to study the nuclear collective motions. Especially the vibrational excitations in rotating nuclei, which are rather difficult to access by usual heavy-ion fusion reactions, can be investigated in detail. Combined with the famous 8{pi}-Spectrometer, which was one of the best {gamma}-ray detector and had discovered some of superdeformed bands, such Coulomb excitation experiments had been carried out at Chalk River laboratory just before it`s shutdown of physics division. In this meeting some of the experimental data are presented and compared with the results of theoretical investigations. (author)
Stability Test for 2-D Continuous-Discrete Systems
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Models of 2-D continuous-discrete systems are introduced, which can be used to describe some complex systems. Different from classical 2-D continuous systems or 2-D discrete systems, the asymptotic stability of the continuous-discrete systems is determined by Hurwitz-Schur stability (hybrid one) of 2-D characteristic polynomials of the systems. An algebraic algorithm with simpler test procedure for Hurwitz-Schur stability test of 2-D polynomials is developed. An example to illustrate the applications of the test approach is provided.
Lifescience Database Archive (English)
Full Text Available el for vortioxetine and CYP2D6 FDA Label for acetaminophen,tramadol and CYP2D6 FDA Label for dextromethorphan... Label for vortioxetine and CYP2D6 European Medicines Agency (EMA) Label for dextromethorphan,quinidine and ...ore of this label. Read more. last updated 10/25/2013 FDA Label for dextromethorphan, quinidine and CYP2D6 O...of NUEDEXTA is a CYP2D6 inhibitor used to increase the plasma availability of dextromethorphan, which is met... 05/02/2014 European Medicines Agency (EMA) Label for dextromethorphan, quinidine
3D/2D Registration of medical images
Tomaževič, D.
2008-01-01
The topic of this doctoral dissertation is registration of 3D medical images to corresponding projective 2D images, referred to as 3D/2D registration. There are numerous possible applications of 3D/2D registration in image-aided diagnosis and treatment. In most of the applications, 3D/2D registration provides the location and orientation of the structures in a preoperative 3D CT or MR image with respect to intraoperative 2D X-ray images. The proposed doctoral dissertation tries to find origin...
Analysis list: Mef2d [Chip-atlas[Archive
Lifescience Database Archive (English)
Full Text Available Mef2d Muscle + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Mef2d.1.ts...v http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Mef2d.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Mef2d....10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Mef2d.Muscle.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Muscle.gml ...
CYP2D7 sequence variation interferes with TaqMan CYP2D6*15 and *35 genotyping
Directory of Open Access Journals (Sweden)
Amanda K Riffel
2016-01-01
Full Text Available TaqMan™ genotyping assays are widely used to genotype CYP2D6, which encodes a major drug metabolizing enzyme. Assay design for CYP2D6 can be challenging owing to the presence of two pseudogenes, CYP2D7 and CYP2D8, structural and copy number variation and numerous single nucleotide polymorphisms (SNPs some of which reflect the wild-type sequence of the CYP2D7 pseudogene. The aim of this study was to identify the mechanism causing false positive CYP2D6*15 calls and remediate those by redesigning and validating alternative TaqMan genotype assays. Among 13,866 DNA samples genotyped by the CompanionDx® lab on the OpenArray platform, 70 samples were identified as heterozygotes for 137Tins, the key SNP of CYP2D6*15. However, only 15 samples were confirmed when tested with the Luminex xTAG CYP2D6 Kit and sequencing of CYP2D6-specific long range (XL-PCR products. Genotype and gene resequencing of CYP2D6 and CYP2D7-specific XL-PCR products revealed a CC>GT dinucleotide SNP in exon 1 of CYP2D7 that reverts the sequence to CYP2D6 and allows a TaqMan assay PCR primer to bind. Because CYP2D7 also carries a Tins, a false-positive mutation signal is generated. This CYP2D7 SNP was also responsible for generating false-positive signals for rs769258 (CYP2D6*35 which is also located in exon 1. Although alternative CYP2D6*15 and *35 assays resolved the issue, we discovered a novel CYP2D6*15 subvariant in one sample that carries additional SNPs preventing detection with the alternate assay. The frequency of CYP2D6*15 was 0.1% in this ethnically diverse U.S. population sample. In addition, we also discovered linkage between the CYP2D7 CC>GT dinucleotide SNP and the 77G>A (rs28371696 SNP of CYP2D6*43. The frequency of this tentatively functional allele was 0.2%. Taken together, these findings emphasize that regardless of how careful genotyping assays are designed and evaluated before being commercially marketed, rare or unknown SNPs underneath primer and/or probe
Backscattering in a 2D topological insulator and the conductivity of a 2D strip
Magarill, L. I.; Entin, M. V.
2015-01-01
A strip of the 2D HgTe topological insulator is studied. The same-spin edge states in an ideal system propagate in opposite directions on different sides of the strip and do not mix by tunneling. Impurities, edge irregularities, and phonons produce transitions between the counterpropagating edge states on different edges. This backscattering determines the conductivity of an infinitely long strip. The conductivity at finite temperature is determined in the framework of the kinetic equation. It is found that the conductivity exponentially grows with the strip width. In the same approximation the nonlocal resistance coefficients of a four-terminal strip are found.
Residual lens effects in 2D mode of auto-stereoscopic lenticular-based switchable 2D/3D displays
Sluijter, M.; IJzerman, W. L.; de Boer, D. K. G.; de Zwart, S. T.
2006-04-01
We discuss residual lens effects in multi-view switchable auto-stereoscopic lenticular-based 2D/3D displays. With the introduction of a switchable lenticular, it is possible to switch between a 2D mode and a 3D mode. The 2D mode displays conventional content, whereas the 3D mode provides the sensation of depth to the viewer. The uniformity of a display in the 2D mode is quantified by the quality parameter modulation depth. In order to reduce the modulation depth in the 2D mode, birefringent lens plates are investigated analytically and numerically, by ray tracing. We can conclude that the modulation depth in the 2D mode can be substantially decreased by using birefringent lens plates with a perfect index match between lens material and lens plate. Birefringent lens plates do not disturb the 3D performance of a switchable 2D/3D display.
Coulomb repulsion in (TMTSF)2X and (TMTTF)2X
DEFF Research Database (Denmark)
Mortensen, Kell; Engler, E. M.
1985-01-01
On the basis of studies of transport properties of (TMTSF)2 X, (TMTTF)2X and their binary alloys the authors discuss the role of on-site Coulomb repulsion relative to the transfer integrals. In TMTTF-salts U/ta are believed to be large, resulting in a Hubbard gap, whereas U/ta in TMTSF-salts are ...
Canonical derivation of the Vlasov-Coulomb noncanonical Poisson structure
Energy Technology Data Exchange (ETDEWEB)
Kaufman, A.N.; Dewar, R.L.
1983-09-01
Starting from a Lagrangian formulation of the Vlasov-Coulomb system, canonical methods are used to define a Poisson structure for this system. Successive changes of representation then lead systematically to the noncanonical Lie-Poisson structure for functionals of the Vlasov distribution.
Coulomb and nuclear effects in breakup and reaction cross sections
Descouvemont, Pierre; Hussein, Mahir S
2016-01-01
We use a three-body Continuum Discretized Coupled Channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term, and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation, and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li + 208Pb. For breakup, we investigate various aspects, such as the role of the alpha + t continuum, the angular-momentum distribution, and the balance between Coulomb and nuclear effects. We show that there is a large ambiguity in defining the 'Coulomb' and 'nuclear' breakup cross sections, since both techniques, although providing the same total breakup cross sections, strongly differ for the individual components. We suggest...
Fast Electron Repulsion Integrals for Molecular Coulomb Sturmians
DEFF Research Database (Denmark)
Avery, James Emil
2013-01-01
of hyperspherical harmonics. A rudimentary software library has been implemented and preliminary benchmarks indicate very good performance: On average 40 ns, or approximately 80 clock cycles, per electron repulsion integral. This makes molecular Coulomb Sturmians competitive with Gaussian type orbitals in terms...
Integrating over the Coulomb branch in N=2 gauge theory
Marino, Marcos; Moore, Gregory
1997-01-01
We review the relation of certain integrals over the Coulomb phase of $d=4$, N=2 SO(3) supersymmetric Yang-Mills theory with Donaldson-Witten theory. We describe a new way to write an important contact term in the theory and show how the integrals generalize to higher rank gauge groups.
Coulomb blockade and superuniversality of the theta angle
Burmistrov, I.S.; Pruisken, A.M.M.
2008-01-01
Based on the Ambegaokar-Eckern-Schön approach to the Coulomb blockade, we develop a complete quantum theory of the single electron transistor. We identify a previously unrecognized physical observable in the problem that, unlike the usual average charge on the island, is robustly quantized for any f
Revised variational approach to QCD in Coulomb gauge
Campagnari, Davide R; Reinhardt, Hugo; Vastag, Peter
2016-01-01
The variational approach to QCD in Coulomb gauge is revisited. By assuming the non-Abelian Coulomb potential to be given by the sum of its infrared and ultraviolet parts, i.e.~by a linearly rising potential and an ordinary Coulomb potential, and by using a Slater determinant ansatz for the quark wave functional, which contains the coupling of the quarks and the gluons with two different Dirac structures, we obtain variational equations for the kernels of the fermionic vacuum wave functional, which are free of ultraviolet divergences. Thereby, a Gaussian type wave functional is assumed for the gluonic part of the vacuum. By using the results of the pure Yang--Mills sector for the gluon propagator as input, we solve the equations for the fermionic kernels numerically and calculate the quark condensate and the effective quark mass in leading order. Assuming a value of $\\sigma_{\\mathrm{C}} = 2.5 \\sigma$ for the Coulomb string tension (where $\\sigma$ is the usual Wilsonian string tension) the phenomenological valu...
Interpolating the Coulomb Phase of Little String Theory
Lin, Ying-Hsuan; Wang, Yifan; Yin, Xi
2015-01-01
We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. We also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.
Exchange Coulomb interaction in nanotubes: Dispersion of Langmuir waves
Andreev, P A
2015-01-01
Microscopic derivation of the Coulomb exchange interaction for electrons located on the nanotubes is presented. Our derivation is based on the many-particle quantum hydrodynamic method. We demonstrate the role of the curvature of the nanocylinders on the force of the exchange interaction. We calculate corresponding dispersion dependencies for electron oscillations on the nanotubes.
The Coulomb law and atomic levels in a superstrong B
Directory of Open Access Journals (Sweden)
Vysotsky M.I.
2014-04-01
Full Text Available The spectrum of atomic levels of hydrogen-like ions originating from the lowest Landau level in an external homogeneous superstrong magnetic field is obtained. The influence of the screening of the Coulomb potential on the values of critical nuclear charges is studied.
Application of Designer Polynomials to the Soft-Coulomb Potential
Weatherford, Charles; Wynn, Albert, III; Red, Eddie; Mathis, Clausell
2004-05-01
In a recent article [C.A. Weatherford, E. Red, A. Wynn III, International Journal of Quantum Chemistry 90, 1289-1294 (2002)], an algorithm was described whereby a synthetic weighted polynomial basis may be constructed which is adapted (designed) to a particular potential. It was applied therein to the Schroedinger equation with a coulomb potential in one dimension (-1/|x| ). A weighted polynomial basis with weight function w(x)=exp(-a|x|) was employed. It was observed that this potential had no even parity solutions - only odd parity solutions. The question arises as to the relationship of the solutions (eigenfunctions and eigenvalues) for this hard coulomb potential to the solutions for the soft coulomb potential (-1/ √x^2+b^2^1/2 ). In particular, since the soft coulomb potential is clearly expected to possess both even and odd parity solutions, how do these solutions behave as b->0 and thus what happens to the even solutions. This problem is deceptively difficult none of the standard basis sets produce a variational minimum as a function of 'a' for nonzero 'b'. This is apparently why this problem has never been done before. A new orthonormal basis was designed with weight function w(x)=exp(-a√x^2+b^2) which did produce a variational minimum for variable a and arbitrary fixed 'b'. The present paper describes these solutions and clearly indicates how they behave as b->0 .
Existence of the thermodynamic limit for disordered quantum Coulomb systems
Blanc, Xavier
2012-01-01
Following a recent method introduced by C. Hainzl, J.P. Solovej and the second author of this article, we prove the existence of the thermodynamic limit for a system made of quantum electrons, and classical nuclei whose positions and charges are randomly perturbed in an ergodic fashion. All the particles interact through Coulomb forces.
Plasmon-mediated Coulomb drag between graphene waveguides
DEFF Research Database (Denmark)
Shylau, Artsem A.; Jauho, Antti-Pekka
2014-01-01
We analyze theoretically charge transport in Coulomb coupled graphene waveguides (GWGs). The GWGs are defined using antidot lattices, and the lateral geometry bypasses many technological challenges of earlier designs. The drag resistivity ρD, which is a measure of the many-particle interactions...
Functional characterization of a first avian cytochrome P450 of the CYP2D subfamily (CYP2D49.
Directory of Open Access Journals (Sweden)
Hua Cai
Full Text Available The CYP2D family members are instrumental in the metabolism of 20-25% of commonly prescribed drugs. Although many CYP2D isoforms have been well characterized in other animal models, research concerning the chicken CYP2Ds is limited. In this study, a cDNA encoding a novel CYP2D enzyme (CYP2D49 was cloned from the chicken liver for the first time. The CYP2D49 cDNA contained an open reading frame of 502 amino acids that shared 52%-57% identities with other CYP2Ds. The gene structure and neighboring genes of CYP2D49 are conserved and similar to those of human CYP2D6. Additionally, similar to human CYP2D6, CYP2D49 is un-inducible in the liver and expressed predominantly in the liver, kidney and small intestine, with detectable levels in several other tissues. Metabolic assays of the CYP2D49 protein heterologously expressed in E. coli and Hela cells indicated that CYP2D49 metabolized the human CYP2D6 substrate, bufuralol, but not debrisoquine. Moreover, quinidine, a potent inhibitor of human CYP2D6, only inhibited the bufuralol 1'-hydroxylation activity of CYP2D49 to a negligible degree. All these results indicated that CYP2D49 had functional characteristics similar to those of human CYP2D6 but measurably differed in the debrisoquine 4'-hydroxylation and quinidine inhibitory profile. Further structure-function investigations that employed site-directed mutagenesis and circular dichroism spectroscopy identified the importance of Val-126, Glu-222, Asp-306, Phe-486 and Phe-488 in keeping the enzymatic activity of CYP2D49 toward bufuralol as well as the importance of Asp-306, Phe-486 and Phe-488 in maintaining the conformation of CYP2D49 protein. The current study is only the first step in characterizing the metabolic mechanism of CYP2D49; further studies are still required.
The No-Hair Conjecture in 2D Dilaton Supergravity
Gamboa-Rios, J
1993-01-01
We study two dimensional dilaton gravity and supergravity following hamiltonian methods. Firstly, we consider the structure of constraints of 2D dilaton gravity and then the 2D dilaton supergravity is obtained taking the squere root of the bosonic constraints. We integrate exactly the equations of motion in both cases and we show that the solutions of the equation of motion of 2D dilaton supergravity differs from the solutions of 2D dilaton gravity only by boundary conditions on the fermionic variables, i.e. the black holes of 2D dilaton supergravity theory are exactly the same black holes of 2D bosonic dilaton gravity modulo supersymmetry transformations. This result is the bidimensional analogue of the no-hair theorem for supergravity.
Scalable Fabrication of 2D Semiconducting Crystals for Future Electronics
Directory of Open Access Journals (Sweden)
Jiantong Li
2015-12-01
Full Text Available Two-dimensional (2D layered materials are anticipated to be promising for future electronics. However, their electronic applications are severely restricted by the availability of such materials with high quality and at a large scale. In this review, we introduce systematically versatile scalable synthesis techniques in the literature for high-crystallinity large-area 2D semiconducting materials, especially transition metal dichalcogenides, and 2D material-based advanced structures, such as 2D alloys, 2D heterostructures and 2D material devices engineered at the wafer scale. Systematic comparison among different techniques is conducted with respect to device performance. The present status and the perspective for future electronics are discussed.
Optimization and practical implementation of ultrafast 2D NMR experiments
Queiroz Júnior,Luiz H. K.; Antonio G. Ferreira; Patrick Giraudeau
2013-01-01
Ultrafast 2D NMR is a powerful methodology that allows recording of a 2D NMR spectrum in a fraction of second. However, due to the numerous non-conventional parameters involved in this methodology its implementation is no trivial task. Here, an optimized experimental protocol is carefully described to ensure efficient implementation of ultrafast NMR. The ultrafast spectra resulting from this implementation are presented based on the example of two widely used 2D NMR experiments, COSY and HSQC...
Coulombic interactions during advection-dominated transport of ions in porous media
Muniruzzaman, Muhammad; Stolze, Lucien; Rolle, Massimo
2017-04-01
Solute transport of charged species in porous media is significantly affected by the electrochemical migration term resulting from the charge-induced interactions among dissolved ions and with solid surfaces. Therefore, the characterization of such Coulombic interactions and their effect on multicomponent ionic transport is of critical importance for assessing the fate of charged solutes in porous media. In this work we present a detailed investigation of the electrochemical effects during conservative multicomponent ionic transport in homogeneous and heterogeneous domains by means of laboratory bench-scale experiments and numerical simulations. The investigation aims at quantifying the key role of small-scale electrostatic interactions in flow-through systems, especially when advection is the dominant mass-transfer process. Considering dilute solutions of strong electrolytes (e.g., MgCl2 and NaBr) we report results showing the important role of Coulombic interactions in the lateral displacement of the different ionic species for steady-state transport scenarios in which the solutions are continuously injected through different portions of the flow-through chamber [1, 2]. Successively, we focus our attention on transient transport and pulse injection of the electrolytes. In these experiments high-resolution spatial and temporal monitoring of the ions' concentrations (600 samples; 1800 concentration measurements), at closely spaced outlet ports (5 mm), allowed us resolving the effects of charge interactions on the temporal breakthrough and spatial profiles of the cations and anions [3]. The interpretation of the experimental results requires a multicomponent modeling approach with an accurate description of local hydrodynamic dispersion, as well as the explicit quantification of the dispersive fluxes' cross-coupling due to the Coulombic interactions between the charged species. A new 2-D simulator [4], coupling the solution of the multicomponent ionic transport
On the role of deformed Coulomb potential in fusion using energy density formalism
Indian Academy of Sciences (India)
Lavneet Kaur; Raj Kumari
2015-10-01
Using the Skyrme energy density formalism, the effect of deformed Coulomb potential on fusion barriers and fusion cross-sections is studied. Our detailed study reveals that the fusion barriers as well as fusion probabilities depend on the shape deformation (due to deformed Coulomb potential) of the colliding nuclei. However, this dependence due to deformed Coulomb potential is found to be very weak.
Energy Technology Data Exchange (ETDEWEB)
Zheng, B.; Croxall, A. F.; Waldie, J., E-mail: jw353@cam.ac.uk; Sfigakis, F.; Farrer, I.; Beere, H. E.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Das Gupta, K. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India)
2016-02-08
We present measurements of Coulomb drag in an ambipolar GaAs/AlGaAs double quantum well structure that can be configured as both an electron-hole bilayer and a hole-hole bilayer, with an insulating barrier of only 10 nm between the two quantum wells. Coulomb drag resistivity is a direct measure of the strength of interlayer particle-particle interactions. We explore the strongly interacting regime of low carrier densities (2D interaction parameter r{sub s} up to 14). Our ambipolar device design allows a comparison between the effects of the attractive electron-hole and repulsive hole-hole interactions and also shows the effects of the different effective masses of electrons and holes in GaAs.
Chae, Dongho; Constantin, Peter; Wu, Jiahong
2014-09-01
We give an example of a well posed, finite energy, 2D incompressible active scalar equation with the same scaling as the surface quasi-geostrophic equation and prove that it can produce finite time singularities. In spite of its simplicity, this seems to be the first such example. Further, we construct explicit solutions of the 2D Boussinesq equations whose gradients grow exponentially in time for all time. In addition, we introduce a variant of the 2D Boussinesq equations which is perhaps a more faithful companion of the 3D axisymmetric Euler equations than the usual 2D Boussinesq equations.
The Effects of Static Coulomb Stress Change on Southern California Earthquake Forecasting
Strader, Anne Elizabeth
I investigate how inclusion of static Coulomb stress changes, caused by tectonic loading and previous seismicity, contributes to the effectiveness and reliability of prospective earthquake forecasts. Several studies have shown that positive static Coulomb stress changes are associated with increased seismicity, relative to stress shadows. However, it is difficult to avoid bias when the learning and testing intervals are chosen retrospectively. I hypothesize that earthquake forecasts based on static Coulomb stress fields may improve upon existing earthquake forecasts based on historical seismicity. Within southern California, I have confirmed the aforementioned relationship between earthquake location and Coulomb stress change, but found no identifiable triggering threshold based on static Coulomb stress history at individual earthquake locations. I have also converted static Coulomb stress changes into spatially-varying earthquake rates by optimizing an index function and calculating probabilities of cells containing at least one earthquake based on Coulomb stress ranges. Inclusion of Coulomb stress effects gives an improvement in earthquake forecasts that is significant with 95% confidence, compared to smoothed seismicity null forecasts. Because of large uncertainties in Coulomb stress calculations near faults (and aftershock distributions), I combine static Coulomb stress and smoothed seismicity into a hybrid earthquake forecast. Evaluating such forecasts against those in which only Coulomb stress or smoothed seismicity determines earthquake rates indicates that Coulomb stress is more effective in the far field, whereas statistical seismology outperforms Coulomb stress near faults. Additionally, I test effects of receiver plane orientation, stress type (normal and shear components), and declustering receiver earthquakes. While static Coulomb stress shows significant potential in a prospective earthquake forecast, simplifying assumptions compromise its
New Type of 2-D Laser Doppler Vibrometer
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The fundamentals and method of 2-D laser Doppler vibrometer are introduced．The factors influencing the measuring accuracy are analyzed. Moreover, the circuit for signal processing is designed. The vibrating amplitude and frequency of 2-D vibration in wider range can be measured simultaneously in non-contact means，the measuring results are accurate.
Animación 2D: curriculum vitae animado
CANTOS BELMONTE, CONSUELO
2015-01-01
Trabajo Fin de Grado de animación 2D donde un personaje (alter ego de la animadora) expone, mediante la interación con una Voz en Off y su sombra, el curriclum vitae de la animadora. Cantos Belmonte, C. (2014). Animación 2D: curriculum vitae animado. http://hdl.handle.net/10251/45910. Archivo delegado
Symmetries and solvable models for evaporating 2D black holes
Cruz, J; Navarro-Salas, J; Talavera, C F
1997-01-01
We study the evaporation process of a 2D black hole in thermal equilibrium when the ingoing radiation is switched off suddenly. We also introduce global symmetries of generic 2D dilaton gravity models which generalize the extra symmetry of the CGHS model.
From 2D Lithography to 3D Patterning
Van Zeijl, H.W.; Wei, J.; Shen, C.; Verhaar, T.M.; Sarro, P.M.
2010-01-01
Lithography as developed for IC device fabrication is a high volume high accuracy patterning technology with strong 2 dimensional (2D) characteristics. This 2D nature makes it a challenge to integrate this technology in a 3 dimensional (3D) manufacturing environment. This article addresses the perfo
Two-Dimensional Gel Electrophoresis and 2D-DIGE.
Meleady, Paula
2018-01-01
Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) continues to be one of the most versatile and widely used techniques to study the proteome of a biological system. In particular, a modified version of 2D-PAGE, two-dimensional difference gel electrophoresis (2D-DIGE), which uses differential labeling of protein samples with up to three fluorescent tags, offers greater sensitivity and reproducibility over conventional 2D-PAGE gels for differential quantitative analysis of protein expression between experimental groups. Both these methods have distinct advantages in the separation and identification of thousands of individual proteins species including protein isoforms and post-translational modifications. This review will discuss the principles of 2D-PAGE and 2D-DIGE including limitations to the methods. 2D-PAGE and 2D-DIGE continue to be popular methods in bioprocessing-related research (particularly on recombinant Chinese hamster ovary cells), which will also be discussed in the review chapter.
From 2D Lithography to 3D Patterning
Van Zeijl, H.W.; Wei, J.; Shen, C.; Verhaar, T.M.; Sarro, P.M.
2010-01-01
Lithography as developed for IC device fabrication is a high volume high accuracy patterning technology with strong 2 dimensional (2D) characteristics. This 2D nature makes it a challenge to integrate this technology in a 3 dimensional (3D) manufacturing environment. This article addresses the
Cascading Constrained 2-D Arrays using Periodic Merging Arrays
DEFF Research Database (Denmark)
Forchhammer, Søren; Laursen, Torben Vaarby
2003-01-01
We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes....... Numerical results for the capacities are presented....
Energy Efficiency of D2D Multi-User Cooperation.
Zhang, Zufan; Wang, Lu; Zhang, Jie
2017-03-28
The Device-to-Device (D2D) communication system is an important part of heterogeneous networks. It has great potential to improve spectrum efficiency, throughput and energy efficiency cooperation of multiple D2D users with the advantage of direct communication. When cooperating, D2D users expend extraordinary energy to relay data to other D2D users. Hence, the remaining energy of D2D users determines the life of the system. This paper proposes a cooperation scheme for multiple D2D users who reuse the orthogonal spectrum and are interested in the same data by aiming to solve the energy problem of D2D users. Considering both energy availability and the Signal to Noise Ratio (SNR) of each D2D user, the Kuhn-Munkres algorithm is introduced in the cooperation scheme to solve relay selection problems. Thus, the cooperation issue is transformed into a maximum weighted matching (MWM) problem. In order to enhance energy efficiency without the deterioration of Quality of Service (QoS), the link outage probability is derived according to the Shannon Equation by considering the data rate and delay. The simulation studies the relationships among the number of cooperative users, the length of shared data, the number of data packets and energy efficiency.
The relation between Euclidean and Lorentzian 2D quantum gravity
Ambjørn, J.; Correia, J.; Kristjansen, C.; Loll, R.
2006-01-01
Starting from 2D Euclidean quantum gravity, we show that one recovers 2D Lorentzian quantum gravity by removing all baby universes. Using a peeling procedure to decompose the discrete, triangulated geometries along a one-dimensional path, we explicitly associate with each Euclidean space-time a (gen
Synthesis and chemistry of elemental 2D materials
Energy Technology Data Exchange (ETDEWEB)
Mannix, Andrew J.; Kiraly, Brian T.; Hersam, Mark C.; Guisinger, Nathan P.
2017-01-25
2D materials have attracted considerable attention in the past decade for their superlative physical properties. These materials consist of atomically thin sheets exhibiting covalent in-plane bonding and weak interlayer and layer-substrate bonding. Following the example of graphene, most emerging 2D materials are derived from structures that can be isolated from bulk phases of layered materials, which form a limited library for new materials discovery. Entirely synthetic 2D materials provide access to a greater range of properties through the choice of constituent elements and substrates. Of particular interest are elemental 2D materials, because they provide the most chemically tractable case for synthetic exploration. In this Review, we explore the progress made in the synthesis and chemistry of synthetic elemental 2D materials, and offer perspectives and challenges for the future of this emerging field.
2D materials and van der Waals heterostructures.
Novoselov, K S; Mishchenko, A; Carvalho, A; Castro Neto, A H
2016-07-29
The physics of two-dimensional (2D) materials and heterostructures based on such crystals has been developing extremely fast. With these new materials, truly 2D physics has begun to appear (for instance, the absence of long-range order, 2D excitons, commensurate-incommensurate transition, etc.). Novel heterostructure devices--such as tunneling transistors, resonant tunneling diodes, and light-emitting diodes--are also starting to emerge. Composed from individual 2D crystals, such devices use the properties of those materials to create functionalities that are not accessible in other heterostructures. Here we review the properties of novel 2D crystals and examine how their properties are used in new heterostructure devices.
Coulomb Artifacts and Bottomonium Hyperfine Splitting in Lattice NRQCD
Liu, Tao; Rayyan, Ahmed
2016-01-01
We study the role of the lattice artifacts associated with the Coulomb binding effects in the analysis of the heavy quarkonium within lattice NRQCD. We find that a "na\\"ive" perturbative matching generates spurious linear Coulomb artifacts, which result in a large systematic error in the lattice predictions for the heavy quarkonium spectrum. This effect is responsible, in particular, for the discrepancy between the recent determinations of the bottomonium hyperfine splitting in the radiatively improved lattice NRQCD [1, 2]. We show that the correct matching procedure which provides full control over discretization errors is based on the asymptotic expansion of the lattice theory about the continuum limit, which gives $M_{\\Upsilon(1S)}-M_{\\eta_b(1S)}=52.9\\pm 5.5~{\\rm MeV}$ [1].
Glassy Dynamics in Geometrically Frustrated Coulomb Liquids without Disorder
Mahmoudian, Samiyeh; Rademaker, Louk; Ralko, Arnaud; Fratini, Simone; Dobrosavljević, Vladimir
2015-07-01
We show that introducing long-range Coulomb interactions immediately lifts the massive ground state degeneracy induced by geometric frustration for electrons on quarter-filled triangular lattices in the classical limit. Important consequences include the stabilization of a stripe-ordered crystalline (global) ground state, but also the emergence of very many low-lying metastable states with amorphous "stripe-glass" spatial structures. Melting of the stripe order thus leads to a frustrated Coulomb liquid at intermediate temperatures, showing remarkably slow (viscous) dynamics, with very long relaxation times growing in Arrhenius fashion upon cooling, as typical of strong glass formers. On shorter time scales, the system falls out of equilibrium and displays the aging phenomena characteristic of supercooled liquids above the glass transition. Our results show remarkable similarity with the recent observations of charge-glass behavior in ultraclean triangular organic materials of the θ -(BEDT -TTF )2 family.
Structure of light neutron-rich nuclei through Coulomb dissociation
Indian Academy of Sciences (India)
U Datta Pramanik; T Aumann; D Cortina; H Emling; H Geissel; M Hellström; R Holzmann; N Iwasa; Y Leifels; G Münzenberg; M Rejmund; C Scheidenberger; K Sümmerer; A Leistenschneider; Th W Elze; A Grünschloss; S Ilievski; K Boretzky; J V Kratz; R Kulessa; E Lubkiewicz; E Wajda; W Walus; P Reiter; H Simon
2001-08-01
Coulomb breakup of neutron-rich nuclei around mass ∼ 20 has been studied experimentally using secondary beams (∼ 500–600 MeV/u) of unstable nuclei produced at GSI. The spectroscopic factor deduced for the neutron occupying 1/2 level in 15C ground state is consistent with the earlier reported value. The data analysis for Coulomb breakup of 17C shows that most of the cross section yields the 16C core in its excited state. For 17-22O, the low-lying E1 strength amounts up to about 12% of the energy weighted dipole sum rule strength depending on neutron excess. The cluster sum rule limit with 16O as a core is almost exhausted for 17,18O, while for more neutron rich isotopes the strength with respect to that limit decreases.
Scaling laws for near barrier Coulomb and Nuclear Breakup
Hussein, M S; Lubian, J; Otomar, D R; Canto, L F
2013-01-01
We investigate the nuclear and the Coulomb contributions to the breakup cross sections of $^6$Li in collisions with targets in different mass ranges. Comparing cross sections for different targets at collision energies corresponding to the same $E/V_{\\mathrm{\\scriptscriptstyle B}}$, we obtain interesting scaling laws. First, we derive an approximate linear expression for the nuclear breakup cross section as a function of $A_{\\mathrm{% \\scriptscriptstyle T}}^{1/3}$. We then confirm the validity of this expression performing CDCC calculations. Scaling laws for the Coulomb breakup cross section are also investigated. In this case, our CDCC calculations indicate that this cross section has a linear dependence on the atomic number of the target. This behavior is explained by qualitative arguments. Our findings, which are consistent with previously obtained results for higher energies, are important when planning for experiments involving exotic weakly bound nuclei.
Back to epicycles - relativistic Coulomb systems in velocity space
Ben-Ya'acov, Uri
2017-05-01
The study of relativistic Coulomb systems in velocity space is prompted by the fact that the study of Newtonian Kepler/Coulomb systems in velocity space, although less familiar than the analytic solutions in ordinary space, provides a much simpler (also more elegant) method. The simplicity and elegance of the velocity-space method derives from the linearity of the velocity equation, which is the unique feature of 1/r interactions for Newtonian and relativistic systems alike. The various types of possible trajectories are presented, their properties deduced from the orbits in velocity space, accompanied with illustrations. In particular, it is found that the orbits traversed in the relativistic velocity space (which is hyperbolic (H 3) rather than Euclidean) are epicyclic - circles whose centres also rotate - thus the title. Dedicated to the memory of J. D. Bekenstein - physicist, teacher and human
Direct simulation Monte Carlo schemes for Coulomb interactions in plasmas
Dimarco, Giacomo; Pareschi, Lorenzo
2010-01-01
We consider the development of Monte Carlo schemes for molecules with Coulomb interactions. We generalize the classic algorithms of Bird and Nanbu-Babovsky for rarefied gas dynamics to the Coulomb case thanks to the approximation introduced by Bobylev and Nanbu (Theory of collision algorithms for gases and plasmas based on the Boltzmann equation and the Landau-Fokker-Planck equation, Physical Review E, Vol. 61, 2000). Thus, instead of considering the original Boltzmann collision operator, the schemes are constructed through the use of an approximated Boltzmann operator. With the above choice larger time steps are possible in simulations; moreover the expensive acceptance-rejection procedure for collisions is avoided and every particle collides. Error analysis and comparisons with the original Bobylev-Nanbu (BN) scheme are performed. The numerical results show agreement with the theoretical convergence rate of the approximated Boltzmann operator and the better performance of Bird-type schemes with respect to t...
Structural phase transitions and topological defects in ion Coulomb crystals
Energy Technology Data Exchange (ETDEWEB)
Partner, Heather L. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Nigmatullin, Ramil [Institute of Quantum Physics, Albert-Einstein Allee-11, Ulm University, 89069 Ulm (Germany); Burgermeister, Tobias; Keller, Jonas; Pyka, Karsten [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Plenio, Martin B. [Center for Integrated Quantum Science and Technology, Albert-Einstein-Allee 11, Ulm University, 89069 Ulm (Germany); Institute for Theoretical Physics, Albert-Einstein-Allee 11, Ulm University, 89069 Ulm (Germany); Retzker, Alex [Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Givat Ram (Israel); Zurek, Wojciech H. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Campo, Adolfo del [Department of Physics, University of Massachusetts Boston, Boston, MA 02125 (United States); Mehlstäubler, Tanja E., E-mail: tanja.mehlstaeubler@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)
2015-03-01
We use laser-cooled ion Coulomb crystals in the well-controlled environment of a harmonic radiofrequency ion trap to investigate phase transitions and defect formation. Topological defects in ion Coulomb crystals (kinks) have been recently proposed for studies of nonlinear physics with solitons and as carriers of quantum information. Defects form when a symmetry breaking phase transition is crossed nonadiabatically. For a second order phase transition, the Kibble–Zurek mechanism predicts that the formation of these defects follows a power law scaling in the rate of the transition. We demonstrate a scaling of defect density and describe kink dynamics and stability. We further discuss the implementation of mass defects and electric fields as first steps toward controlled kink preparation and manipulation.
Coulomb effects in low-energy nuclear fragmentation
Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah
1993-01-01
Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.
Structural phase transitions and topological defects in ion Coulomb crystals
Energy Technology Data Exchange (ETDEWEB)
Partner, Heather L. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Nigmatullin, Ramil [Institute of Quantum Physics, Ulm Univ., Ulm (Germany); Burgermeister, Tobias [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Keller, Jonas [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Pyka, Karsten [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Plenio, Martin B. [Center for Integrated Quantum Science and Technology, Ulm Univ., Ulm, (Germany):Institute for Theoretical Physics, Ulm Univ.,Ulm, (Germany); Retzker, Alex [Racah Institute of Physics, The Hebrew University of Jerusalem, Givat Ram (Israel); Zurek, Wojciech Hubert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); del Campo, Adolfo [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Physics; Mehlstaubler, Tanja E. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)
2014-11-19
We use laser-cooled ion Coulomb crystals in the well-controlled environment of a harmonic radiofrequency ion trap to investigate phase transitions and defect formation. Topological defects in ion Coulomb crystals (kinks) have been recently proposed for studies of nonlinear physics with solitons and as carriers of quantum information. Defects form when a symmetry breaking phase transition is crossed non-adiabatically. For a second order phase transition, the Kibble-Zurek mechanism predicts that the formation of these defects follows a power law scaling in the rate of the transition. We demonstrate a scaling of defect density and describe kink dynamics and stability. We further discuss the implementation of mass defects and electric fields as first steps toward controlled kink preparation and manipulation.
Time-resolved studies of interatomic Coulombic decay
Energy Technology Data Exchange (ETDEWEB)
Frühling, U. [Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Trinter, F. [Institut für Kernphysik, Goethe Universität, Max-von-Laue-Str.1, 60438 Frankfurt (Germany); Karimi, F. [Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Williams, J.B. [Institut für Kernphysik, Goethe Universität, Max-von-Laue-Str.1, 60438 Frankfurt (Germany); Jahnke, T., E-mail: jahnke@atom.uni-frankfurt.de [Institut für Kernphysik, Goethe Universität, Max-von-Laue-Str.1, 60438 Frankfurt (Germany)
2015-10-15
Interatomic Coulombic decay (ICD) is a decay mechanism occurring in loosely bound matter, e.g. in systems bound by van der Waals-forces or hydrogen bonds. In many such cases the decay time is similar to the time scale of nuclear motion during the decay. As the efficiency of ICD strongly depends on the internuclear distance of the atoms or molecules involved in the decay, an overall non-trivial temporal decay behavior arises. The progress of examining the time-domain aspects of interatomic Coulombic decay is summarized in this short topical review with a special emphasis on experiments that are now feasible due to the developments of free-electron lasers.
Effect of Coulomb Screening Length on Nuclear Pasta Simulations
Alcain, P N; Nichols, J I; Dorso, C O
2013-01-01
We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semi-classical molecular dynamics model, studying isospin symmetric matter at sub-saturation densities and low temperatures. The electrostatic interaction between protons interaction is included in the form of a screened Coulomb potential in the spirit of the Thomas-Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the non-homogeneous nuclear structures known as ``nuclear pasta''. As the screening length increases, we can a transition from a one-per-cell pasta regime (due exclusively to finite size effects) to a more appealing multiple pasta per simulation box. This shows qualitative difference in the structure of neutron star matter at low temperatures, and therefore, special caution should be taken when the screening length is estimated for numerical simulat...
Low-energy Coulomb excitation of Sr,9896 beams
Clément, E.; Zielińska, M.; Péru, S.; Goutte, H.; Hilaire, S.; Görgen, A.; Korten, W.; Doherty, D. T.; Bastin, B.; Bauer, C.; Blazhev, A.; Bree, N.; Bruyneel, B.; Butler, P. A.; Butterworth, J.; Cederkäll, J.; Delahaye, P.; Dijon, A.; Ekström, A.; Fitzpatrick, C.; Fransen, C.; Georgiev, G.; Gernhäuser, R.; Hess, H.; Iwanicki, J.; Jenkins, D. G.; Larsen, A. C.; Ljungvall, J.; Lutter, R.; Marley, P.; Moschner, K.; Napiorkowski, P. J.; Pakarinen, J.; Petts, A.; Reiter, P.; Renstrøm, T.; Seidlitz, M.; Siebeck, B.; Siem, S.; Sotty, C.; Srebrny, J.; Stefanescu, I.; Tveten, G. M.; Van de Walle, J.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.; De Witte, H.; Wrzosek-Lipska, K.
2016-11-01
The structure of neutron-rich Sr,9896 nuclei was investigated by low-energy safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN, with the MINIBALL spectrometer. A rich set of transitional and diagonal E 2 matrix elements, including those for non-yrast structures, has been extracted from the differential Coulomb-excitation cross sections. The results support the scenario of a shape transition at N =60 , giving rise to the coexistence of a highly deformed prolate and a spherical configuration in 98Sr, and are compared to predictions from several theoretical calculations. The experimental data suggest a significant contribution of the triaxal degree of freedom in the ground state of both isotopes. In addition, experimental information on low-lying states in 98Rb has been obtained.
Coulomb oscillations in three-layer graphene nanostructures
Energy Technology Data Exchange (ETDEWEB)
Guettinger, J; Stampfer, C; Molitor, F; Graf, D; Ihn, T; Ensslin, K [Solid State Physics Laboratory, ETH Zurich, 8093 Zurich (Switzerland)], E-mail: guettinj@phys.ethz.ch
2008-12-15
We present transport measurements on a tunable three-layer graphene single electron transistor (SET). The device consists of an etched three-layer graphene flake with two narrow constrictions separating the island from source and drain contacts. Three lateral graphene gates are used to electrostatically tune the device. An individual three-layer graphene constriction has been investigated separately showing a transport gap near the charge neutrality point. The graphene tunneling barriers show a strongly nonmonotonic coupling as a function of gate voltage indicating the presence of localized states in the constrictions. We show Coulomb oscillations and Coulomb diamond measurements proving the functionality of the graphene SET. A charging energy of {approx}0.6 meV is extracted.
Coulomb field of an accelerated charge physical and mathematical aspects
Alexander, F J; Alexander, Francis J.; Gerlach, Ulrich H.
1991-01-01
The Maxwell field equations relative to a uniformly accelerated frame, and the variational principle from which they are obtained, are formulated in terms of the technique of geometrical gauge invariant potentials. They refer to the transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge invariant "2+2" decomposition is used to see how the Coulomb field of a charge, static in an accelerated frame, has properties that suggest features of electromagnetism which are different from those in an inertial frame. In particular, (1) an illustrative calculation shows that the Larmor radiation reaction equals the electrostatic attraction between the accelerated charge and the charge induced on the surface whose history is the event horizon, and (2) a spectral decomposition of the Coulomb potential in the accelerated frame suggests the possibility that the distortive effects of this charge on the Rindler vacuum are akin to those of a charge on a crystal lattice.
Confining Dyon-Anti-Dyon Coulomb Liquid Model I
Liu, Yizhuang; Zahed, Ismail
2015-01-01
We revisit the dyon-anti-dyon liquid model for the Yang-Mills confining vacuum discussed by Diakonov and Petrov, by retaining the effects of the classical interactions mediated by the streamline between the dyons and anti-dyons. In the SU(2) case the model describes a 4-component strongly interacting Coulomb liquid in the center symmetric phase. We show that in the linearized screening approximation the streamline interactions yield Debye-Huckel type corrections to the bulk parameters such as the pressure and densities, but do not alter significantly the large distance behavior of the correlation functions in leading order. The static scalar and charged structure factors are consistent with a plasma of a dyon-anti-dyon liquid with a Coulomb parameter $\\Gamma_{D\\bar D}\\approx 1$ in the dyon-anti-dyon channel. Heavy quarks are still linearly confined and the large spatial Wilson loops still exhibit area laws in leading order.
Coulomb and Nuclear Breakup at Low Energies: Scaling Laws
Directory of Open Access Journals (Sweden)
Hussein M. S.
2013-12-01
Full Text Available We report on a recent work on the low-energy behavior of the breakup cross section in so far as it has important role in the fusion of weakly bound and halo nuclei at near-barrier energies. We assess the way the nuclear component of this cross section scales with the target mass. In complete accord with previous finding at higher energies we verify that the low energy behavior of the breakup cross section for a given projectile and relative center of mass energy with respect to the Coulomb barrier height scales as the cubic root of the mass number of the target. Surprisingly we find that the Coulomb component of the breakup cross section at these low energies also obeys scaling, but with a linear dependence on the target charge. Our findings are important when planning for experiments involving these exotic nuclei.
Femtosecond Studies Of Coulomb Explosion Utilizing Covariance Mapping
Card, D A
2000-01-01
The studies presented herein elucidate details of the Coulomb explosion event initiated through the interaction of molecular clusters with an intense femtosecond laser beam (≥1 PW/cm2). Clusters studied include ammonia, titanium-hydrocarbon, pyridine, and 7-azaindole. Covariance analysis is presented as a general technique to study the dynamical processes in clusters and to discern whether the fragmentation channels are competitive. Positive covariance determinations identify concerted processes such as the concomitant explosion of protonated cluster ions of asymmetrical size. Anti- covariance mapping is exploited to distinguish competitive reaction channels such as the production of highly charged nitrogen atoms formed at the expense of the protonated members of a cluster ion ensemble. This technique is exemplified in each cluster system studied. Kinetic energy analyses, from experiment and simulation, are presented to fully understand the Coulomb explosion event. A cutoff study strongly suggests that...
Applicability of the molecular dynamics technique to a Coulomb plasma
Energy Technology Data Exchange (ETDEWEB)
Zhidkov, A.G.; Galeev, R.Kh.
1993-09-01
In the present work, we report the calculations of the local Lyapunov parameter which determines the nature of the motion for a system of n particles interacting according to Coulomb`s law. These calculations have been performed for the most probable states of a fully ionized plasma, and they were performed using a Microvax-3 computer with the NAG(FO2) program package for a plasma consisting of particles with the same mass and for a fully ionized hydrogen plasma. The particle coordinates were prescribed as a uniformly distributed set of random numbers obtained using the NAG(GO5) routine. Results for the Lyapunov parameter are presented, and it is shown that the values of the parameter increases sharply as a function of particle number up to n=100 and then saturate. This latter observation is attributed to shielding, related to Debye effects.
Renormalization group analysis of graphene with a supercritical Coulomb impurity
Nishida, Yusuke
2016-01-01
We develop a field theoretical approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov-Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.
Interplay of Coulomb interaction and spin-orbit coupling
Bünemann, Jörg; Linneweber, Thorben; Löw, Ute; Anders, Frithjof B.; Gebhard, Florian
2016-07-01
We employ the Gutzwiller variational approach to investigate the interplay of Coulomb interaction and spin-orbit coupling in a three-orbital Hubbard model. Already in the paramagnetic phase we find a substantial renormalization of the spin-orbit coupling that enters the effective single-particle Hamiltonian for the quasiparticles. Only close to half band-filling and for sizable Coulomb interaction do we observe clear signatures of Hund's atomic rules for spin, orbital, and total angular momentum. For a finite local Hund's rule exchange interaction we find a ferromagnetically ordered state. The spin-orbit coupling considerably reduces the size of the ordered moment, it generates a small ordered orbital moment, and it induces a magnetic anisotropy. To investigate the magnetic anisotropy energy, we use an external magnetic field that tilts the magnetic moment away from the easy axis (1 ,1 ,1 ) .
Coulomb Traps and Charge Transport in Molecular Solids
Scher, Harvey
2000-03-01
A major result of experimental studies of a diverse assortment of disordered molecular solids is the observation of a common pattern in the charge transport properties. The transport ranges from charge transfer between molecules doped in an inert polymer to motion along the silicon backbone of polysilylenes. The pattern is the unusual combination of Poole Frenkel-like electric field dependence and non-Arrhenius temperature dependence of the mobility. The latter feature has been especially puzzling. We study the drift mobility of a molecular polaron in the presence of an applied field and Coulomb traps. The model is based on one previously developed for geminate recombination of photogenerated charge carriers. The key electric field and temperature dependencies of the mobility measurements are well reproduced by this model. Our conclusion is that this nearly universal transport behavior arises from competition between rates of polaron trapping and release from a very low density of Coulomb traps.
Renormalization group analysis of graphene with a supercritical Coulomb impurity
Nishida, Yusuke
2016-08-01
We develop a field-theoretic approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov-Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial-wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power-law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.
An entropic form for NLFP with coulombic-like potential
Energy Technology Data Exchange (ETDEWEB)
Grassi, A., E-mail: agrassi@unict.it [Dipartimento di Scienze del Farmaco, Università di Catania, V.le A. Doria 6, 95125 Catania (Italy)
2012-01-30
Here it is proposed a new entropy form for which it is possible to obtain a stationary solution of the Non-Linear Fokker–Planck equation (NLFP) with coulombic-like potentials. The general properties of this new entropy form are shown and the results are compared with those obtained by other entropy forms. Finally, the behavior of the stationary solution in presence of two point charges is also shown. -- Highlights: ► In this Letter we have proposed a new form of entropy. ► Starting from this new entropy form a Non-Linear Fokker–Planck equation has been derived. ► The stationary solution of the Non-Linear Fokker–Planck equation is obtained by using an external coulombic-like potential. ► A comparison with other forms of entropies has been proposed in the case of a single or two point charges.
Coulomb-Born-Oppenheimer approximation in Ps-H scattering
Indian Academy of Sciences (India)
Hasi Ray
2006-02-01
To improve the Coulomb-Born approximation (CBA) theory of ionization in positronium (Ps) and atom scattering, the effect of exchange is introduced. The nine-dimensional exchange amplitude for ionization of Ps in Ps-H scattering is reduced to a two-dimensional integral using the present Coulomb-Born-Oppenheimer approximation (CBOA). The methodology is extremely useful to evaluate ionization parameters for different target systems and for different types of ionization processes. It is then applied to evaluate the Ps-ionization cross-section and to estimate the effect of exchange on Ps-ionization in Ps-H system. We establish the importance of exchange at lower energy region.
Low-Temperature Kinetics and Dynamics with Coulomb Crystals
Heazlewood, Brianna R.; Softley, Timothy P.
2015-04-01
Coulomb crystals-as a source of translationally cold, highly localized ions-are being increasingly utilized in the investigation of ion-molecule reaction dynamics in the cold regime. To develop a fundamental understanding of ion-molecule reactions, and to challenge existing models that describe the rates, product branching ratios, and temperature dependence of such processes, investigators need to exercise full control over the experimental reaction parameters. This requires not only state selection of the reactants, but also control over the collision process (e.g., the collisional energy and angular momentum) and state-selective product detection. The combination of Coulomb crystals in ion traps with cold neutral-molecule sources is enabling the measurement of state-selective reaction rates in a diverse range of systems. With the development of appropriate product detection techniques, we are moving toward the ultimate goal of examining low-energy, state-to-state ion-molecule reaction dynamics.
Evaluation of Coulomb Energy Difference for Light Mirror Nuclei Using Slater—Type Orbitals
Institute of Scientific and Technical Information of China (English)
F.Oner; R.A.Mamedoy
2002-01-01
Behavior of the Coulomb energy difference for light nuclei is explained in terms of the different values of the average Coulomb interaction between two particles.Coulomb energy difference according to shell model of light mirror nuclei in the Coulomb and exchange integrals in the formula can be explained with exponential-type wavefunctions.In this study,using the one-center expansion of exponential-type wavefunctions in terms of Slater-type orbitals with the same center,we derived formula for Coulomb energy difference of light mirror nuclei.
Evaluation of Coulomb Energy Difference for Light Mirror Nuclei Using Slater-Type Orbitals
Institute of Scientific and Technical Information of China (English)
F. Oner; B.A. Mainedov
2002-01-01
Behavior of the Coulomb energy difference for light nuclei is explained in terms of the different values of theaverage Coulomb interaction between two particles. Coulomb energy difference according to shell model of light mirrornuclei in the Coulomb and exchange integrals in the formula can be explained with exponential-type wavefunctions. Inthis study, using the one-center expansion of exponential-type wavcfunctions in terms of Slater-type orbitals with thesame center, we derived formula for Coulomb energy difference of light mirror mulei.
Coulomb Interactions and Mesoscopic Effects in Carbon Nanotubes
Kane, Charlie; Balents, Leon; Fisher, Matthew
1997-01-01
We argue that long-range Coulomb forces convert an isolated (N,N) armchair carbon nanotube into a strongly-renormalized *Luttinger liquid*. At high temperatures, we find anomalous temperature dependences for the interaction and impurity contributions to the resistivity, and similar power-law dependences for the local tunneling density of states. At low temperatures, the nanotube exhibits spin-charge separation, visible as an extra energy scale in the discrete tunneling density of states (for ...
Molecular Dynamics Simulation of Shear Moduli for Coulomb Crystals
Horowitz, C J
2008-01-01
Torsional (shear) oscillations of neutron stars may have been observed in quasiperiodic oscillations of Magnetar Giant Flares. The frequencies of these modes depend on the shear modulus of neutron star crust. We calculate the shear modulus of Coulomb crystals from molecular dynamics simulations. We find that electron screening reduces the shear modulus by about 10% compared to previous Ogata et al. results. Our MD simulations can be extended to calculate the effects of impurities and or polycrystalline structures on the shear modulus.
PT-invariant one-dimensional Coulomb problem
Sinha, A K; Sinha, Anjana; Roychoudhury, Rajkumar
2002-01-01
The one-dimensional Coulomb-like potential with a real coupling constant beta, and a centrifugal-like core of strength G = alpha^2 - {1/4}, viz. V(x) = {alpha^2 - (1/4)}/{(x-ic)^2} + beta/|x-ic|, is discussed in the framework of PT-symmetry. The PT-invariant exactly solvable model so formed, is found to admit a double set of real and discrete energies, numbered by a quasi-parity q = +/- 1.
Coulomb excitation of 144,146,148,150Nd
Ahmad, A.; Bomar, G.; Crowell, H.; Hamilton, J. H.; Kawakami, H.; Maguire, C. F.; Nettles, W. G.; Piercey, R. B.; Ramayya, A. V.; Soundranayagam, R.; Ronningen, R. M.; Scholten, O.; Stelson, P. H.
1988-01-01
Coulomb excitation of 144,146,148,1605060Nd by 10.5 and 11 MeV alpha particles was studied by magnetic analysis of particles scattered into 150°. Values of B(E20+-->2+) for the 2+ states at 696, 454, 302, and 130 keV are 0.58(1), 0.78(1), 1.390(20), and 2.816(35) e2b2, respectively. For 148,150Nd, v
Coulombic potentials in the semi-classical limit
Energy Technology Data Exchange (ETDEWEB)
Chantelau, K. (Technische Univ. Berlin (Germany, F.R.). Fachbereich 3 - Mathematik)
1990-05-01
This paper is devoted to Schroedinger operators in two dimensions with singular (Coulombic) potentials. We investigate the behaviour of the eigenvalues at the bottom of the spectrum in the semi-classical limit. To overcome the difficulties due to the singularities, we use some kind of generalisation of the Levi-Civita transform. After this regularisation, we apply the theory of Helffer and Sjoestrand to get the full asymptotics for the eigenvalues. (orig.).
Coulomb Sturmians as a basis for molecular calculations
DEFF Research Database (Denmark)
Avery, John Scales; Avery, James Emil
2012-01-01
Almost all modern quantum chemistry programs use Gaussian basis sets even though Gaussians cannot accurately represent the cusp at atomic nuclei, nor can they represent the slow decay of the wave function at large distances. The reason that Gaussians dominate quantum chemistry today is the great...... of hyperspherical harmonics. For the remaining many-centre integrals, Coulomb Sturmians are shown to have advantages over other ETOs. Pilot calculations are performed on N-electron molecules using the Generalized Sturmian Method....
Electron interactions in graphene through an effective Coulomb potential
Rodrigues, Joao N. B.; Adam, Shaffique
A recent numerical work [H.-K. Tang et al, PRL 115, 186602 (2015)] considering graphene's π-electrons interacting through an effective Coulomb potential that is finite at short-distances, stressed the importance of the sp2 -electrons in determining the semimetal to Mott insulator phase transition in graphene. Some years ago, I. F. Herbut [PRL 97, 146401 (2006)] studied such a transition by mapping graphene's π-electrons into a Gross-Neveu model. From a different perspective, D. T. Son [PRB 75, 235423 (2007)] put the emphasis on the long-range interactions by modelling graphene as Dirac fermions interacting through a bare Coulomb potential. Here we build on these works and explore the phase diagram of Dirac fermions interacting through an effective Coulomb-like potential screened at short-distances. The interaction potential used allows for analytic results that controllably switch between the two perspectives above. This work was supported by the Singapore National Research Foundation (NRF-NRFF2012-01 and CA2DM medium-sized centre program) and by the Singapore Ministry of Education and Yale-NUS College (R-607-265-01312).
The EMC effect of Nuclear Matter with Coulomb Corrections
Li, Shujie; Solvignon, Patricia; Arrington, John; Gaskell, Dave
2016-09-01
Extraction of the EMC effect for nuclear matter is of great interest since it allows comparison to theoretical calculations in a regime where ``exact'' nuclear wave functions can be used. Earlier extractions from (e,e') cross sections ignored the contribution of the Coulomb distortion, which can be approximated as an electron energy shift on the order of MeV. Though small, this shift can cause a noticeable change in cross sections in certain kinematic regimes. In this study, we applied Coulomb corrections on the per-nucleon ratios from the published SLAC E139 data and preliminary JLAB E03-103 data. I will show preliminary results for an extrapolation of the EMC ratios from finite nuclei to symmetric nuclear matter, including Coulomb Corrections and examining the sensitivity to different approximations for the nuclear density. The data from two experiments will also be combined to study the nuclear dependence of R =σL /σT . Supported in part by DOE Grant No. DE-AC05-06OR23177, No. DE-AC02-06CH11357, and No. DE-SC0014168.
Implosive Interatomic Coulombic decay in the simplest molecular anion
Greene, Chris H.; Perez-Rios, Jesus; Slipchenko, Lyudmila
2016-05-01
Interatomic Coulombic decay (ICD) has been extensively studied in different systems: from diatomic systems such as He2 up to more complex chemical systems with interest in biochemistry. Independently of the size and complexity of the system, the ICD process proposed involves the emission of an electron through exchange of a virtual photon. The present theoretical study investigates the ICD process in the helium hydride anion, which involves two final product states that can be produced through a Coulomb implosion following high energy ejection of a He 1s electron accompanied by excitation to He+(n = 2) . One of the subsequent decay channels is associated with the usual emission of a single electron, to produce a stable molecule: HeH+, which can compete with the usual dissociated final state of the system. The second channel involves the emission of two electrons, leading to the usual Coulomb explosion of the final product ions He+(1 s) + H + . In addition, the process of formation of the helium hydride anion is analyzed in terms of the existing technology of ionic molecular beams and buffer gas cooling techniques. This work is supported by the National Science Foundation under Grant PHY-1306905.
Regularized friction and continuation: Comparison with Coulomb's law
Vigué, Pierre; Vergez, Christophe; Karkar, Sami; Cochelin, Bruno
2017-02-01
Periodic solutions of systems with friction are difficult to investigate because of the non-smooth nature of friction laws. This paper examines periodic solutions and most notably stick-slip, on a simple one-degree-of-freedom system (mass, spring, damper, and belt), with Coulomb's friction law, and with a regularized friction law (i.e. the friction coefficient becomes a function of relative speed, with a stiffness parameter). With Coulomb's law, the stick-slip solution is constructed step by step, which gives a usable existence condition. With the regularized law, the Asymptotic Numerical Method and the Harmonic Balance Method provide bifurcation diagrams with respect to the belt speed or normal force, and for several values of the regularization parameter. Formulations from the Coulomb case give the means of a comparison between regularized solutions and a standard reference. With an appropriate definition, regularized stick-slip motion exists, its amplitude increases with respect to the belt speed and its pulsation decreases with respect to the normal force.
Coulomb Collision for Plasma Simulations: Modelling and Numerical Methods
Geiser, Juergen
2016-09-01
We are motivated to model weakly ionized Plasma applications. The modeling problem is based on an incorporated explicit velocity-dependent small-angle Coulomb collision terms into a Fokker-Planck equation. Such a collision is done with so called test and field particles, which are scattered stochastically based on a Langevin equation. Based on such different model approaches, means the transport part is done with kinetic equations, while the collision part is done via the Langevin equations, we present a splitting of these models. Such a splitting allow us to combine different modeling parts. For the transport part, we can apply particle models and solve them with particle methods, e.g., PIC, while for the collision part, we can apply the explicit Coulomb collision model, e.g., with fast stochastic differential equation solvers. Additional, we also apply multiscale approaches for the different parts of the transport part, e.g., different time-scales of an explicit electric field, and model-order reduction approaches. We present first numerical results for particle simulations with the deterministic-stochastic splitting schemes. Such ideas can be applied to sputtering problems or plasma applications with dominant Coulomb collisions.
Structure and Interaction in 2D Assemblies of Tobacco Mosaic Viruses
Energy Technology Data Exchange (ETDEWEB)
Fukuto, M.; Yang, L.; Wang, S.; Fukuto, M.; Checco, A.; Niu, Z.; Wang, Q.
2009-12-07
We created two-dimensional (2D) assemblies of tobacco mosaic viruses (TMVs) and characterized their structures using Atomic Force Microscopy (AFM) and X-ray scattering. The TMVs were adsorbed on an oppositely charged, fluid lipid monolayer supported by a solid substrate and submerged in a buffer solution. The lipid monolayer confined the viral particles within a plane, while providing them with lateral mobility so that overall the TMV assembly behaved like a 2D liquid. We controlled the inter-particle interaction by adjusting the chemical condition in the buffer to induce ordered TMV assemblies. We found that the presence of the lipid layer was essential for forming ordered TMV assemblies. Packed TMV assemblies formed on the lipid layer, with an average inter-particle spacing of 42 nm. By introducing Ca{sup 2+} ions into the buffer solution, we were able to improve the in-plane order within the TMV assemblies and reduce the average inter-particle spacing to 20 nm, compared to the TMV diameter of 18 nm. Quantitative analysis of the X-ray scattering data shows that the structural order within the TMV assemblies prepared under a Ca{sup 2+}-free buffer solution is consistent with purely repulsive, electrostatic inter-particle interaction. In contrast, the structural order within Ca{sup 2+}-induced TMV assemblies is consistent with the behavior of a fluid of sticky rods, implying the presence of a strong attraction between TMVs. In addition to the screening of Coulomb repulsion, this behavior is likely the result of counterion-induced as well as membrane-mediated attractions.
Structure and interaction in 2D assemblies of tobacco mosaic viruses
Energy Technology Data Exchange (ETDEWEB)
Yang, L.; Wang. S.; Masafumi, F.; Checco, A.; Zhongwei, N.; Wang, Q.
2009-08-27
We created two-dimensional (2D) assemblies of tobacco mosaic viruses (TMVs) and characterized their structures using Atomic Force Microscopy (AFM) and X-ray scattering. The TMVs were adsorbed on an oppositely charged, fluid lipid monolayer supported by a solid substrate and submerged in a buffer solution. The lipid monolayer confined the viral particles within a plane, while providing them with lateral mobility so that overall the TMV assembly behaved like a 2D liquid. We controlled the inter-particle interaction by adjusting the chemical condition in the buffer to induce ordered TMV assemblies. We found that the presence of the lipid layer was essential for forming ordered TMV assemblies. Packed TMV assemblies formed on the lipid layer, with an average inter-particle spacing of 42 nm. By introducing Ca2+ ions into the buffer solution, we were able to improve the in-plane order within the TMV assemblies and reduce the average inter-particle spacing to 20 nm, compared to the TMV diameter of 18 nm. Quantitative analysis of the X-ray scattering data shows that the structural order within the TMV assemblies prepared under a Ca{sup 2+}-free buffer solution is consistent with purely repulsive, electrostatic inter-particle interaction. In contrast, the structural order within Ca{sup 2+}-induced TMV assemblies is consistent with the behavior of a fluid of sticky rods, implying the presence of a strong attraction between TMVs. In addition to the screening of Coulomb repulsion, this behavior is likely the result of counterion-induced as well as membrane-mediated attractions.
Vacuum polarization of planar Dirac fermions by a superstrong Coulomb potential
Khalilov, V R
2016-01-01
We study the vacuum polarization of planar charged Dirac fermions by a strong Coulomb potential. Induced vacuum charge density is calculated and analyzed at the subcritical and supercritical Coulomb potentials for massless and massive fermions. For the massless case the induced vacuum charge density is localized at the origin when the Coulomb center charge is subcritical while it has a power-law tail when the Coulomb center charge is supercritical. The finite mass contribution into the induced charge due to the vacuum polarization is small and insignificantly distorts the Coulomb potential only at distances of order of the Compton length. The induced vacuum charge has a screening sign. As is known the quantum electrodynamics vacuum becomes unstable when the Coulomb center charge is increased from subcritical to supercritical values. In the supercritical Coulomb potential the quantum electrodynamics vacuum acquires the charge due to the so-called real vacuum polarization. We calculate the real vacuum polarizat...
2d Affine XY-Spin Model/4d Gauge Theory Duality and Deconfinement
Energy Technology Data Exchange (ETDEWEB)
Anber, Mohamed M.; Poppitz, Erich; /Toronto U.; Unsal, Mithat; /SLAC /Stanford U., Phys. Dept. /San Francisco State U.
2012-08-16
We introduce a duality between two-dimensional XY-spin models with symmetry-breaking perturbations and certain four-dimensional SU(2) and SU(2) = Z{sub 2} gauge theories, compactified on a small spatial circle R{sup 1,2} x S{sup 1}, and considered at temperatures near the deconfinement transition. In a Euclidean set up, the theory is defined on R{sup 2} x T{sup 2}. Similarly, thermal gauge theories of higher rank are dual to new families of 'affine' XY-spin models with perturbations. For rank two, these are related to models used to describe the melting of a 2d crystal with a triangular lattice. The connection is made through a multi-component electric-magnetic Coulomb gas representation for both systems. Perturbations in the spin system map to topological defects in the gauge theory, such as monopole-instantons or magnetic bions, and the vortices in the spin system map to the electrically charged W-bosons in field theory (or vice versa, depending on the duality frame). The duality permits one to use the two-dimensional technology of spin systems to study the thermal deconfinement and discrete chiral transitions in four-dimensional SU(N{sub c}) gauge theories with n{sub f} {ge} 1 adjoint Weyl fermions.
Quantum information experiments with 2D arrays of hundreds of trapped ions
Gilmore, Kevin; Bohnet, Justin; Sawyer, Brian; Britton, Joseph; Wall, Michael; Foss-Feig, Michael; Rey, Ana Maria; Bollinger, John
2016-05-01
We summarize recent experimental work with 2D arrays of hundreds of trapped 9 Be+ ions stored in a Penning trap. Penning traps utilize static magnetic and electric fields to confine ions, and enable the trapping and laser cooling of ion crystals larger than typically possible in RF ion traps. We work with single-plane ion crystals where the ions form a triangular lattice through minimization of their Coulomb potential energy. The crystals rotate, and we present numerical studies that determine optimal operating parameters for producing low temperature, stable 2-dimensional crystals with Doppler laser cooling and a rotating wall potential. Our qubit is the electron spin-flip transition in the ground state of 9 Be+ and is sensitive to magnetic field fluctuations. Through mitigation of part-per-billion, vibration-induced magnetic field fluctuations we demonstrate T2 coherence times longer than 50 ms. We engineer long-range Ising interactions with spin-dependent optical dipole forces, and summarize recent measurements that characterize the entanglement generated through single-axis twisting. Supported by: JILA-NSF-PFC-1125844, NSF-PHY-1521080, ARO, AFOSR, AFOSR-MURI.
Mapping of the photo-induced metastable and hidden phases in 2D electronic materials
Zhou, Faran; Sun, Tianyin; Han, Tzong-Ru; Malliakas, Christos; Duxbury, Phillip; Mahanti, Subhendra; Kanatzidis, Mercouri; Ruan, Chong-Yu; MSU Team; NU Team
Using the ultrafast electron imaging techniques, we studied the light-induced phase transitions in transition-metal dichalcogenide materials. A succession of different phases was introduced transiently using femtosecond mid-infrared pulses and the local atomic scale charge-density-wave dynamics and morphological evolution of the long-range textured domains were in situ characterized using the ultrashort coherent electron pulses. The various metastable and hidden states emerging under the controlled nonthermal, nonadiabatic driving highlight the interaction-driven nature of these transitions with limited involvement of lattice entropy. The methodology introduced here can be generally applied to survey the complex energy landscape in strongly correlated electron systems, avoiding the difficulty of electrostatic gating or confounding effects due to defects and/or disorder. In particular, the observation of robust non-thermal switching at meso-scales and at ultrafast timescales, provides a platform for designing high-speed low-energy consumption nano-photonics and electronics devices.
2D Pauli Equation with Hulthén Potential in the Presence of Aharonov-Bohm Effect
Institute of Scientific and Technical Information of China (English)
N.Ferkous; A.Bounames
2013-01-01
The 2D Pauli equation with Hulthén potential for spin-1/2 particle in the presence of Aharonov-Bohm (AB) field is solved analytically,on the assumption that an effective approximation is used for the centrifugai term.Singular and regular solutions of the problem are obtained.It is shown that the AB field lifts the degeneracy of the energy levels.The range of the flux parameter for which singular solutions are allowed is modified compared to the pure AB case.When the screening parameter vanishes,it is shown that the obtained energy spectrum becomes the same as that of the Aharonov-Bohm Coulomb problem.
2D vs. 3D mammography observer study
Fernandez, James Reza F.; Hovanessian-Larsen, Linda; Liu, Brent
2011-03-01
Breast cancer is the most common type of non-skin cancer in women. 2D mammography is a screening tool to aid in the early detection of breast cancer, but has diagnostic limitations of overlapping tissues, especially in dense breasts. 3D mammography has the potential to improve detection outcomes by increasing specificity, and a new 3D screening tool with a 3D display for mammography aims to improve performance and efficiency as compared to 2D mammography. An observer study using a mammography phantom was performed to compare traditional 2D mammography with this ne 3D mammography technique. In comparing 3D and 2D mammography there was no difference in calcification detection, and mass detection was better in 2D as compared to 3D. There was a significant decrease in reading time for masses, calcifications, and normals in 3D compared to 2D, however, as well as more favorable confidence levels in reading normal cases. Given the limitations of the mammography phantom used, however, a clearer picture in comparing 3D and 2D mammography may be better acquired with the incorporation of human studies in the future.
An automated pipeline to screen membrane protein 2D crystallization.
Kim, Changki; Vink, Martin; Hu, Minghui; Love, James; Stokes, David L; Ubarretxena-Belandia, Iban
2010-06-01
Electron crystallography relies on electron cryomicroscopy of two-dimensional (2D) crystals and is particularly well suited for studying the structure of membrane proteins in their native lipid bilayer environment. To obtain 2D crystals from purified membrane proteins, the detergent in a protein-lipid-detergent ternary mixture must be removed, generally by dialysis, under conditions favoring reconstitution into proteoliposomes and formation of well-ordered lattices. To identify these conditions a wide range of parameters such as pH, lipid composition, lipid-to-protein ratio, ionic strength and ligands must be screened in a procedure involving four steps: crystallization, specimen preparation for electron microscopy, image acquisition, and evaluation. Traditionally, these steps have been carried out manually and, as a result, the scope of 2D crystallization trials has been limited. We have therefore developed an automated pipeline to screen the formation of 2D crystals. We employed a 96-well dialysis block for reconstitution of the target protein over a wide range of conditions designed to promote crystallization. A 96-position magnetic platform and a liquid handling robot were used to prepare negatively stained specimens in parallel. Robotic grid insertion into the electron microscope and computerized image acquisition ensures rapid evaluation of the crystallization screen. To date, 38 2D crystallization screens have been conducted for 15 different membrane proteins, totaling over 3000 individual crystallization experiments. Three of these proteins have yielded diffracting 2D crystals. Our automated pipeline outperforms traditional 2D crystallization methods in terms of throughput and reproducibility.
Wei, Hongjiang; Zhang, Yuyao; Gibbs, Eric; Chen, Nan-Kuei; Wang, Nian; Liu, Chunlei
2017-04-01
Quantitative susceptibility mapping (QSM) measures tissue magnetic susceptibility and typically relies on time-consuming three-dimensional (3D) gradient-echo (GRE) MRI. Recent studies have shown that two-dimensional (2D) multi-slice gradient-echo echo-planar imaging (GRE-EPI), which is commonly used in functional MRI (fMRI) and other dynamic imaging techniques, can also be used to produce data suitable for QSM with much shorter scan times. However, the production of high-quality QSM maps is difficult because data obtained by 2D multi-slice scans often have phase inconsistencies across adjacent slices and strong susceptibility field gradients near air-tissue interfaces. To address these challenges in 2D EPI-based QSM studies, we present a new data processing procedure that integrates 2D and 3D phase processing. First, 2D Laplacian-based phase unwrapping and 2D background phase removal are performed to reduce phase inconsistencies between slices and remove in-plane harmonic components of the background phase. This is followed by 3D background phase removal for the through-plane harmonic components. The proposed phase processing was evaluated with 2D EPI data obtained from healthy volunteers, and compared against conventional 3D phase processing using the same 2D EPI datasets. Our QSM results were also compared with QSM values from time-consuming 3D GRE data, which were taken as ground truth. The experimental results show that this new 2D EPI-based QSM technique can produce quantitative susceptibility measures that are comparable with those of 3D GRE-based QSM across different brain regions (e.g. subcortical iron-rich gray matter, cortical gray and white matter). This new 2D EPI QSM reconstruction method is implemented within STI Suite, which is a comprehensive shareware for susceptibility imaging and quantification. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
2-D Versus 3-D Magnetotelluric Data Interpretation
Ledo, Juanjo
2005-09-01
In recent years, the number of publications dealing with the mathematical and physical 3-D aspects of the magnetotelluric method has increased drastically. However, field experiments on a grid are often impractical and surveys are frequently restricted to single or widely separated profiles. So, in many cases we find ourselves with the following question: is the applicability of the 2-D hypothesis valid to extract geoelectric and geological information from real 3-D environments? The aim of this paper is to explore a few instructive but general situations to understand the basics of a 2-D interpretation of 3-D magnetotelluric data and to determine which data subset (TE-mode or TM-mode) is best for obtaining the electrical conductivity distribution of the subsurface using 2-D techniques. A review of the mathematical and physical fundamentals of the electromagnetic fields generated by a simple 3-D structure allows us to prioritise the choice of modes in a 2-D interpretation of responses influenced by 3-D structures. This analysis is corroborated by numerical results from synthetic models and by real data acquired by other authors. One important result of this analysis is that the mode most unaffected by 3-D effects depends on the position of the 3-D structure with respect to the regional 2-D strike direction. When the 3-D body is normal to the regional strike, the TE-mode is affected mainly by galvanic effects, while the TM-mode is affected by galvanic and inductive effects. In this case, a 2-D interpretation of the TM-mode is prone to error. When the 3-D body is parallel to the regional 2-D strike the TE-mode is affected by galvanic and inductive effects and the TM-mode is affected mainly by galvanic effects, making it more suitable for 2-D interpretation. In general, a wise 2-D interpretation of 3-D magnetotelluric data can be a guide to a reasonable geological interpretation.
Jackson, M I; Hiley, M J; Yeadon, M R
2011-10-13
In the table contact phase of gymnastics vaulting both dynamic and static friction act. The purpose of this study was to develop a method of simulating Coulomb friction that incorporated both dynamic and static phases and to compare the results with those obtained using a pseudo-Coulomb implementation of friction when applied to the table contact phase of gymnastics vaulting. Kinematic data were obtained from an elite level gymnast performing handspring straight somersault vaults using a Vicon optoelectronic motion capture system. An angle-driven computer model of vaulting that simulated the interaction between a seven segment gymnast and a single segment vaulting table during the table contact phase of the vault was developed. Both dynamic and static friction were incorporated within the model by switching between two implementations of the tangential frictional force. Two vaulting trials were used to determine the model parameters using a genetic algorithm to match simulations to recorded performances. A third independent trial was used to evaluate the model and close agreement was found between the simulation and the recorded performance with an overall difference of 13.5%. The two-state simulation model was found to be capable of replicating performance at take-off and also of replicating key contact phase features such as the normal and tangential motion of the hands. The results of the two-state model were compared to those using a pseudo-Coulomb friction implementation within the simulation model. The two-state model achieved similar overall results to those of the pseudo-Coulomb model but obtained solutions more rapidly. Copyright © 2011 Elsevier Ltd. All rights reserved.
Introduction to game physics with Box2D
Parberry, Ian
2013-01-01
Written by a pioneer of game development in academia, Introduction to Game Physics with Box2D covers the theory and practice of 2D game physics in a relaxed and entertaining yet instructional style. It offers a cohesive treatment of the topics and code involved in programming the physics for 2D video games. Focusing on writing elementary game physics code, the first half of the book helps you grasp the challenges of programming game physics from scratch, without libraries or outside help. It examines the mathematical foundation of game physics and illustrates how it is applied in practice thro
2D electron cyclotron emission imaging at ASDEX Upgrade (invited)
Energy Technology Data Exchange (ETDEWEB)
Classen, I. G. J. [Max Planck Institut fuer Plasmaphysik, 85748 Garching (Germany); FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Boom, J. E.; Vries, P. C. de [FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Suttrop, W.; Schmid, E.; Garcia-Munoz, M.; Schneider, P. A. [Max Planck Institut fuer Plasmaphysik, 85748 Garching (Germany); Tobias, B.; Domier, C. W.; Luhmann, N. C. Jr. [University of California at Davis, Davis, California 95616 (United States); Donne, A. J. H. [FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Jaspers, R. J. E. [Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Park, H. K. [POSTECH, Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Munsat, T. [University of Colorado, Boulder, Colorado 80309 (United States)
2010-10-15
The newly installed electron cyclotron emission imaging diagnostic on ASDEX Upgrade provides measurements of the 2D electron temperature dynamics with high spatial and temporal resolution. An overview of the technical and experimental properties of the system is presented. These properties are illustrated by the measurements of the edge localized mode and the reversed shear Alfven eigenmode, showing both the advantage of having a two-dimensional (2D) measurement, as well as some of the limitations of electron cyclotron emission measurements. Furthermore, the application of singular value decomposition as a powerful tool for analyzing and filtering 2D data is presented.
Optimization and practical implementation of ultrafast 2D NMR experiments
Directory of Open Access Journals (Sweden)
Luiz H. K. Queiroz Júnior
2013-01-01
Full Text Available Ultrafast 2D NMR is a powerful methodology that allows recording of a 2D NMR spectrum in a fraction of second. However, due to the numerous non-conventional parameters involved in this methodology its implementation is no trivial task. Here, an optimized experimental protocol is carefully described to ensure efficient implementation of ultrafast NMR. The ultrafast spectra resulting from this implementation are presented based on the example of two widely used 2D NMR experiments, COSY and HSQC, obtained in 0.2 s and 41 s, respectively.
Spin Waves in 2D ferromagnetic square lattice stripe
Ahmed, Maher Z.
2011-01-01
In this work, the area and edges spin wave calculations were carried out using the Heisenberg Hamiltonian and the tridiagonal method for the 2D ferromagnetic square lattice stripe, where the SW modes are characterized by a 1D in-plane wave vector $q_x$. The results show a general and an unexpected feature that the area and edge spin waves only exist as optic modes. This behavior is also seen in 2D Heisenberg antiferromagnetic square lattice. This absence of the acoustic modes in the 2D square...
Optimization and practical implementation of ultrafast 2D NMR experiments
Energy Technology Data Exchange (ETDEWEB)
Queiroz Junior, Luiz H. K., E-mail: professorkeng@gmail.com [Universidade Federal de Sao Carlos (UFSC), SP (Brazil). Departamento de Quimica; Universidade Federal de Goias (UFGO), Goiania, GO (Brazil). Inst. de Quimica; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSC), SP (Brazil). Departamento de Quimica; Giraudeau, Patrick [Universite de Nantes (France). CNRS, Chimie et Interdisciplinarite: Synthese, Analyse, Modelisation
2013-09-01
Ultrafast 2D NMR is a powerful methodology that allows recording of a 2D NMR spectrum in a fraction of second. However, due to the numerous non-conventional parameters involved in this methodology its implementation is no trivial task. Here, an optimized experimental protocol is carefully described to ensure efficient implementation of ultrafast NMR. The ultrafast spectra resulting from this implementation are presented based on the example of two widely used 2D NMR experiments, COSY and HSQC, obtained in 0.2 s and 41 s, respectively. (author)
Harvest Survive : Game Mechanics of Unity 2D Game
2014-01-01
The purpose of this project was to learn how to create Games in Unity 2D, to see the work-flow and to test if the new Unity 2D feature of the Unity engine was a good alternative for developing 2D games. A further aspect was to learn the different steps and mechanics of the Unity environment. The goal was to create a survival game, in which the player would have to grow plants in order to get food and money to stay alive in a hostile environment. The player has to survive in six different...
Kalman Filter for Generalized 2-D Roesser Models
Institute of Scientific and Technical Information of China (English)
SHENG Mei; ZOU Yun
2007-01-01
The design problem of the state filter for the generalized stochastic 2-D Roesser models, which appears when both the state and measurement are simultaneously subjected to the interference from white noise, is discussed. The wellknown Kalman filter design is extended to the generalized 2-D Roesser models. Based on the method of "scanning line by line", the filtering problem of generalized 2-D Roesser models with mode-energy reconstruction is solved. The formula of the optimal filtering, which minimizes the variance of the estimation error of the state vectors, is derived. The validity of the designed filter is verified by the calculation steps and the examples are introduced.
Propagating Uncertainties from Source Model Estimations to Coulomb Stress Changes
Baumann, C.; Jonsson, S.; Woessner, J.
2009-12-01
Multiple studies have shown that static stress changes due to permanent fault displacement trigger earthquakes on the causative and on nearby faults. Calculations of static stress changes in previous studies have been based on fault parameters without considering any source model uncertainties or with crude assumptions about fault model errors based on available different source models. In this study, we investigate the influence of fault model parameter uncertainties on Coulomb Failure Stress change (ΔCFS) calculations by propagating the uncertainties from the fault estimation process to the Coulomb Failure stress changes. We use 2500 sets of correlated model parameters determined for the June 2000 Mw = 5.8 Kleifarvatn earthquake, southwest Iceland, which were estimated by using a repeated optimization procedure and multiple data sets that had been modified by synthetic noise. The model parameters show that the event was predominantly a right-lateral strike-slip earthquake on a north-south striking fault. The variability of the sets of models represents the posterior probability density distribution for the Kleifarvatn source model. First we investigate the influence of individual source model parameters on the ΔCFS calculations. We show through a correlation analysis that for this event, changes in dip, east location, strike, width and in part north location have stronger impact on the Coulomb failure stress changes than changes in fault length, depth, dip-slip and strike-slip. Second we find that the accuracy of Coulomb failure stress changes appears to increase with increasing distance from the fault. The absolute value of the standard deviation decays rapidly with distance within about 5-6 km around the fault from about 3-3.5 MPa down to a few Pa, implying that the influence of parameter changes decrease with increasing distance. This is underlined by the coefficient of variation CV, defined as the ratio of the standard deviation of the Coulomb stress
Dubost, B.; Dubessy, R.; Szymanski, B.; Guibal, S.; Likforman, J.-P.; Guidoni, L.
2014-03-01
We measured by laser spectroscopy the isotope shifts between naturally occurring even isotopes of strontium ions for both the 5s2S1/2→5p2P1/2 (violet) and the 4d2D3/2→5p2P1/2 (infrared) dipole-allowed optical transitions. Fluorescence spectra were taken by simultaneous measurements on a two-component Coulomb crystal in a linear Paul trap containing 103-104 laser-cooled Sr+ ions. The isotope shifts are extracted from the experimental spectra by fitting the data with the analytical solution of the optical Bloch equations describing a three-level atom interacting with two laser beams. This technique allowed us to increase the precision with respect to previously reported data obtained by optogalvanic spectroscopy or fast atomic-beam techniques. The results for the 5s2S1/2→5p2P1/2 transition are ν88-ν84=+378(4) MHz and ν88-ν86=+170(3) MHz, in agreement with previously reported measurements. In the case of the previously unexplored 4d2D3/2→5p2P1/2 transition we find ν88-ν84=-828(4) MHz and ν88-ν86=-402(2) MHz. These results provide more data for stringent tests of theoretical calculations of the isotope shifts of alkali-metal-like atoms. Moreover, they simplify the identification and the addressing of Sr+ isotopes for ion frequency standards or quantum-information-processing applications in the case of multi-isotope ion strings.
Sheridan, M. F.; Stinton, A. J.; Patra, A.; Pitman, E. B.; Bauer, A.; Nichita, C. C.
2005-01-01
The Titan2D geophysical mass-flow model is evaluated by comparing its simulation results and those obtained from another flow model, FLOW3D, with published data on the 1963 Little Tahoma Peak avalanches on Mount Rainier, Washington. The avalanches, totaling approximately 10×10 6 m 3 of broken lava blocks and other debris, traveled 6.8 km horizontally and fell 1.8 km vertically ( H/ L=0.246). Velocities calculated from runup range from 24 to 42 m/s and may have been as high as 130 m/s while the avalanches passed over Emmons Glacier. Titan2D is a code for an incompressible Coulomb continuum; it is a depth-averaged, 'shallow-water', granular-flow model. The conservation equations for mass and momentum are solved with a Coulomb-type friction term at the basal interface. The governing equations are solved on multiple processors using a parallel, adaptive mesh, Godunov scheme. Adaptive gridding dynamically concentrates computing power in regions of special interest; mesh refinement and coarsening key on the perimeter of the moving avalanche. The model flow initiates as a pile defined as an ellipsoid by a height ( z) and an elliptical base defined by radii in the x and y planes. Flow parameters are the internal friction angle and bed friction angle. Results from the model are similar in terms of velocity history, lateral spreading, location of runup areas, and final distribution of the Little Tahoma Peak deposit. The avalanches passed over the Emmons Glacier along their upper flow paths, but lower in the valley they traversed stream gravels and glacial outwash deposits. This presents difficulty in assigning an appropriate bed friction angle for the entire deposit. Incorporation of variable bed friction angles into the model using GIS will help to resolve this issue.
Dubost, Brice; Szymanski, Benjamin; Guibal, Samuel; Likforman, Jean-Pierre; Guidoni, Luca
2014-01-01
We measured by laser spectroscopy the isotope shifts between naturally-occurring even-isotopes of strontium ions for both the $5s\\,\\,^2S_{1/2}\\to 5p\\,\\,^2P_{1/2}$ (violet) and the $4d\\,\\,^2D_{3/2}\\to 5p\\,\\,^2P_{1/2}$ (infrared) dipole-allowed optical transitions. Fluorescence spectra were taken by simultaneous measurements on a two-component Coulomb crystal in a linear Paul trap containing $10^3$--$10^4$ laser-cooled Sr$^+$ ions. The isotope shifts are extracted from the experimental spectra by fitting the data with the analytical solution of the optical Bloch equations describing a three-level atom in interaction with two laser beams. This technique allowed us to increase the precision with respect to previously reported data obtained by optogalvanic spectroscopy or fast atomic-beam techniques. The results for the $5s\\,\\,^2S_{1/2}\\to 5p\\,\\,^2P_{1/2}$ transition are $\
First Principles Calculations of Electronic Excitations in 2D Materials
DEFF Research Database (Denmark)
Rasmussen, Filip Anselm
-thin electronics and high efficiency solar cells. Contrary to many other nano-materials, methods for large scale fabrication and patterning have already been demonstrated and the first real technological applications have already be showcased. Still the technology is very young and the number of well-studied 2D...... materials are few. However as the list of 2D materials is growing it is necessary to investigate their fundamental structural, electronic and optical properties. These are determined by the atomic and electronic structure of the materials that can quite accurately predicted by computational quantum...... as if it is being screened by the electrons in the material. This method has been very successful for calculating quasiparticle energies of bulk materials but results have been more varying for 2D materials. The reason is that the 2D confined electrons are less able to screen the added charge and some...
Illumination Compensation for 2-D Barcode Recognition Basing Morphologic
Directory of Open Access Journals (Sweden)
Jian-Hua Li
2013-04-01
Full Text Available Improvement of image quality has been highly demanded in digital imaging systems. This study presents a novel illumination normalization approach for 2-D barcode recognition under varying lighting conditions. MMs (Morphological transformations are employed to original images using big scale multiple SEs (structuring elements. Then we make use of entropy to fuse images. The performance of proposed methodology is illustrated through the processing of images with different kinds of 2-D barcodes under different backgrounds. The experimental results show that this approach can process different kinds of 2-D barcodes under varying lighting conditions adaptively. Compared with other conventional methods, our proposed approach does a better job in processing 2-D barcode under non-uniform illumination.
Emerging and potential opportunities for 2D flexible nanoelectronics
Zhu, Weinan; Park, Saungeun; Akinwande, Deji
2016-05-01
The last 10 years have seen the emergence of two-dimensional (2D) nanomaterials such as graphene, transition metal dichalcogenides (TMDs), and black phosphorus (BP) among the growing portfolio of layered van der Waals thin films. Graphene, the prototypical 2D material has advanced rapidly in device, circuit and system studies that has resulted in commercial large-area applications. In this work, we provide a perspective of the emerging and potential translational applications of 2D materials including semiconductors, semimetals, and insulators that comprise the basic material set for diverse nanosystems. Applications include RF transceivers, smart systems, the so-called internet of things, and neurotechnology. We will review the DC and RF electronic performance of graphene and BP thin film transistors. 2D materials at sub-um channel length have so far enabled cut-off frequencies from baseband to 100GHz suitable for low-power RF and sub-THz concepts.
CYP2D6 polymorphism in relation to tramadol metabolism
DEFF Research Database (Denmark)
Halling, Jónrit; Weihe, Pál; Brosen, Kim
2008-01-01
Several studies have demonstrated the impact of CYP2D6 polymorphism on the pharmacokinetics of tramadol. However, the relationship between the O-demethylation of tramadol and O-desmethyltramadol (M1) and CYP2D6 activity has not previously been investigated with tramadol in multimedicated...... outpatients under steady-state conditions. Hence, the aim of this study was to determine if the well documented pharmacokinetics of tramadol regarding CYP2D6 could be verified in a study including 88 multimedicated Faroese patients, treated with tramadol at steady-state conditions. Further, the study aimed...... collection over 12 hours. Sparteine and its metabolites were assayed by gas chromatography. Genotype analyses for the CYP2D6 3, 4, 6, and 9 alleles were performed by polymerase chain reaction and Taqman technology. Plasma and urinary concentrations of (+/-)-tramadol and (+/-)-M1 were determined by high...
2D gels still have a niche in proteomics
DEFF Research Database (Denmark)
Rogowska-Wrzesinska, Adelina; Le Bihan, Marie-Catherine; Thaysen-Andersen, Morten;
2013-01-01
) alternative detection methods for modification specific proteomics; 3) identification of protein isoforms and modified proteins. With an example of the glycoprotein TIMP-1 protein we illustrate the unique properties of 2D gels for the separation and characterisation of multiply modified proteins. We also show......With the rapid advance of MS-based proteomics one might think that 2D gel-based proteomics is dead. This is far from the truth. Current research has shown that there are still a number of places in the field of protein and molecular biology where 2D gels still play a leading role. The aim...... of this review is to highlight some of these applications. Examples from our own research as well as from other published works are used to illustrate the 2D gel driven research in the areas of: 1) de novo sequencing and protein identification from organisms with no or incomplete genome sequences available; 2...
Orbifold Reduction and 2d (0,2) Gauge Theories
Franco, Sebastian; Seong, Rak-Kyeong
2016-01-01
We introduce Orbifold Reduction, a new method for generating $2d$ $(0,2)$ gauge theories associated to D1-branes probing singular toric Calabi-Yau 4-folds starting from $4d$ $\\mathcal{N}=1$ gauge theories on D3-branes probing toric Calabi-Yau 3-folds. The new procedure generalizes dimensional reduction and orbifolding. In terms of T-dual configurations, it generates brane brick models starting from brane tilings. Orbifold reduction provides an agile approach for generating $2d$ $(0,2)$ theories with a brane realization. We present three practical applications of the new algorithm: the connection between $4d$ Seiberg duality and $2d$ triality, a combinatorial method for generating theories related by triality and a $2d$ $(0,2)$ generalization of the Klebanov-Witten mass deformation.
Proteome analysis of human colorectal cancer tissue using 2-D ...
African Journals Online (AJOL)
Jane
2010-10-11
Oct 11, 2010 ... Laser capture microdissection and two-dimensional difference gel electrophoresis were used to establish ... As a technique with high-flux and high resolution, pro- teomics ... in which the protein sample was labeled before 2-D.
2-D electromagnetic simulation of passive microstrip circuits
Dueñas Jiménez, Alejandro
2009-01-01
A reference for circuit design engineers and microwave engineers. It uses a simple 2-D electromagnetic simulation procedure to provide basic knowledge and practical insight into quotidian problems of microstrip passive circuits applied to microwave systems and digital technologies.
Materials science: Screen printing of 2D semiconductors
Kim, Young Duck; Hone, James
2017-04-01
Atomically thin semiconductors have been made by transferring the oxide 'skin' of a liquid metal to substrates. This opens the way to the low-cost mass production of 2D semiconductors at the sizes needed for electronics applications.
Use of spatial information in 2D SEMG array decomposition
Smit, C.T.; Kallenberg, L.A.C.; Hermens, Hermanus J.
2007-01-01
A new feature extraction/classification method for High Density surface ElectroMyoGraphy (HD sEMG) Motor Unit Aciton Potential (MUAP) decomposition using 2D shape and energy distribution features is presented and experimentally tested.
Sparse Non-negative Matrix Factor 2-D Deconvolution
DEFF Research Database (Denmark)
Mørup, Morten; Schmidt, Mikkel N.
2006-01-01
We introduce the non-negative matrix factor 2-D deconvolution (NMF2D) model, which decomposes a matrix into a 2-dimensional convolution of two factor matrices. This model is an extension of the non-negative matrix factor deconvolution (NMFD) recently introduced by Smaragdis (2004). We derive...... and prove the convergence of two algorithms for NMF2D based on minimizing the squared error and the Kullback-Leibler divergence respectively. Next, we introduce a sparse non-negative matrix factor 2-D deconvolution model that gives easy interpretable decompositions and devise two algorithms for computing...... this form of factorization. The developed algorithms have been used for source separation and music transcription....
Collins Model and Phase Diagram of 2D Ternary System
Institute of Scientific and Technical Information of China (English)
XIE Chuan-Mei; CHEN Li-Rong
2004-01-01
The Collins model is introduced into the two-dimensional (2D) alternative ternary system having the Lennard-Jones (L-J) potential. The Gibbs free energy of this ternary system is calculated, and according to thermodynamic theory, a group of equations that determine the solid-liquid diagram of ternary system are derived, some isothermal sectional diagrams of the 2D ternary system are obtained. The results are quite similar to the behavior of three-dimensional substances.
A simultaneous 2D/3D autostereo workstation
Chau, Dennis; McGinnis, Bradley; Talandis, Jonas; Leigh, Jason; Peterka, Tom; Knoll, Aaron; Sumer, Aslihan; Papka, Michael; Jellinek, Julius
2012-03-01
We present a novel immersive workstation environment that scientists can use for 3D data exploration and as their everyday 2D computer monitor. Our implementation is based on an autostereoscopic dynamic parallax barrier 2D/3D display, interactive input devices, and a software infrastructure that allows client/server software modules to couple the workstation to scientists' visualization applications. This paper describes the hardware construction and calibration, software components, and a demonstration of our system in nanoscale materials science exploration.
Maximizing the Optical Band Gap in 2D Photonic Crystals
DEFF Research Database (Denmark)
Hougaard, Kristian G.; Sigmund, Ole
Topology optimization is used to find the 2D photonic crystal designs with the largest relative photonic band gaps. Starting points for the topology optimization are found with an exhaustive binary search on a low resolution grid.......Topology optimization is used to find the 2D photonic crystal designs with the largest relative photonic band gaps. Starting points for the topology optimization are found with an exhaustive binary search on a low resolution grid....
New design of 2-D photonic crystal waveguide couplers
Institute of Scientific and Technical Information of China (English)
ZHONG Zhi-rong; ZHANG Li-hua; YANG Hong-qin; JIANG Yun-kun
2006-01-01
@@ Based on couple wave equation and finite-difference time-domain (FDTD) algorithm,the strong couple characteristic of 2-D photonic crystal couplers is calculated.Theoretical analysis and numerical simulated results indicate that the energy in a 2-D photonic crystal coupler can not be totally transferred between two wave-guides.Compared with the result of weak coupling theory,our result is more accurate.
2D IR Correlation Spectroscopy in Wood Science
Directory of Open Access Journals (Sweden)
Carmen Mihaela Popescu
2012-10-01
Full Text Available Generalized 2D correlation spectroscopy is a well-established technique that provides considerable utility and benefit in various spectroscopic studies of polymers. Some of the important features of generalized 2D correlation spectra are simplification of complex spectra consisting of many overlapped peaks, enhancement of spectral resolution by spreading peaks along the second dimension, unambiguous assignments through the correlation of bands selectively coupled by various interaction mechanisms, and determination of the sequence of the spectral peak emergence.
RNA folding pathways and kinetics using 2D energy landscapes.
Senter, Evan; Dotu, Ivan; Clote, Peter
2015-01-01
RNA folding pathways play an important role in various biological processes, such as (i) the hok/sok (host-killing/suppression of killing) system in E. coli to check for sufficient plasmid copy number, (ii) the conformational switch in spliced leader (SL) RNA from Leptomonas collosoma, which controls trans splicing of a portion of the '5 exon, and (iii) riboswitches--portions of the 5' untranslated region of messenger RNA that regulate genes by allostery. Since RNA folding pathways are determined by the energy landscape, we describe a novel algorithm, FFTbor2D, which computes the 2D projection of the energy landscape for a given RNA sequence. Given two metastable secondary structures A, B for a given RNA sequence, FFTbor2D computes the Boltzmann probability p(x, y) = Z(x,y)/Z that a secondary structure has base pair distance x from A and distance y from B. Using polynomial interpolationwith the fast Fourier transform,we compute p(x, y) in O(n(5)) time and O(n(2)) space, which is an improvement over an earlier method, which runs in O(n(7)) time and O(n(4)) space. FFTbor2D has potential applications in synthetic biology, where one might wish to design bistable switches having target metastable structures A, B with favorable pathway kinetics. By inverting the transition probability matrix determined from FFTbor2D output, we show that L. collosoma spliced leader RNA has larger mean first passage time from A to B on the 2D energy landscape, than 97.145% of 20,000 sequences, each having metastable structures A, B. Source code and binaries are freely available for download at http://bioinformatics.bc.edu/clotelab/FFTbor2D. The program FFTbor2D is implemented in C++, with optional OpenMP parallelization primitives.
Generating a 2D Representation of a Complex Data Structure
James, Mark
2006-01-01
A computer program, designed to assist in the development and debugging of other software, generates a two-dimensional (2D) representation of a possibly complex n-dimensional (where n is an integer >2) data structure or abstract rank-n object in that other software. The nature of the 2D representation is such that it can be displayed on a non-graphical output device and distributed by non-graphical means.
QSAR Models for P-450 (2D6) Substrate Activity
DEFF Research Database (Denmark)
Ringsted, Tine; Nikolov, Nikolai Georgiev; Jensen, Gunde Egeskov;
2009-01-01
activity relationship (QSAR) modelling systems. They cross validated (leave-groups-out) with concordances of 71%, 81% and 82%, respectively. Discrete organic European Inventory of Existing Commercial Chemical Substances (EINECS) chemicals were screened to predict an approximate percentage of CYP 2D6...... substrates. These chemicals are potentially present in the environment. The biological importance of the CYP 2D6 and the use of the software mentioned above were discussed....
CYP2D6 variability in populations from Venezuela.
Moreno, Nancy; Flores-Angulo, Carlos; Villegas, Cecilia; Mora, Yuselin
2016-12-01
CYP2D6 is an important cytochrome P450 enzyme that plays an important role in the metabolism of about 25% of currently prescribed drugs. The presence of polymorphisms in the CYP2D6 gene may modulate enzyme level and activity, thereby affecting individual responses to pharmacological treatments. The most prevalent diseases in the admixed population from Venezuela are cardiovascular and cancer, whereas viral, bacterial and parasitic diseases, particularly malaria, are prevalent in Amerindian populations; in the treatment of these diseases, several drugs that are metabolized by CYP2D6 are used. In this work, we reviewed the data on CYP2D6 variability and predicted metabolizer phenotypes, in healthy volunteers of two admixed and five Amerindian populations from Venezuela. The Venezuelan population is very heterogeneous as a result of the genetic admixture of three major ethnical components: Europeans, Africans and Amerindians. There are noticeable inter-regional and inter-population differences in the process of mixing of this population. Hitherto, there are few published studies in Venezuela on CYP2D6; therefore, it is necessary to increase research in this regard, in particular to develop studies with a larger sample size. There is a considerable amount of work remaining before CYP2D6 is integrated into clinical practice in Venezuela.
Technique of Embedding Depth Maps into 2D Images
Institute of Scientific and Technical Information of China (English)
Kazutake Uehira; Hiroshi Unno; Youichi Takashima
2014-01-01
This paper proposes a new technique that is used to embed depth maps into corresponding 2-dimensional (2D) images. Since a 2D image and its depth map are integrated into one type of image format, they can be treated as if they were one 2D image. Thereby, it can reduce the amount of data in 3D images by half and simplify the processes for sending them through networks because the synchronization between images for the left and right eyes becomes unnecessary. We embed depth maps in the quantized discrete cosine transform (DCT) data of 2D images. The key to this technique is whether the depth maps could be embedded into 2D images without perceivably deteriorating their quality. We try to reduce their deterioration by compressing the depth map data by using the differences from the next pixel to the left. We assume that there is only one non-zero pixel at most on one horizontal line in the DCT block because the depth map values change abruptly. We conduct an experiment to evaluate the quality of the 2D images embedded with depth maps and find that satisfactory quality could be achieved.
Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene
National Research Council Canada - National Science Library
Mihnev, Momchil T; Tolsma, John R; Divin, Charles J; Sun, Dong; Asgari, Reza; Polini, Marco; Berger, Claire; de Heer, Walt A; MacDonald, Allan H; Norris, Theodore B
2015-01-01
...) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron-phonon interactions occur primarily within layers and interlayer electrical conductivities are low...
On the Analysis of Intermediate-Energy Coulomb Excitation Experiments
Scheit, Heiko; Glasmacher, Thomas; Motobayashi, Tohru
2008-01-01
In a recent publication (Bertulani et al., PLB 650 (2007) 233 and arXiv:0704.0060v2) the validity of analysis methods used for intermediate-energy Coulomb excitation experiments was called into question. Applying a refined theory large corrections of results in the literature seemed needed. We show that this is not the case and that the large deviations observed are due to the use of the wrong experimental parameters. We furthermore show that an approximate expression derived by Bertulani et al. is in fact equivalent to the theory of Winther and Alder (NPA 319 (1979) 518), an analysis method often used in the literature.
Hydrogenoid orbitals revisited: From Slater orbitals to Coulomb Sturmians
Indian Academy of Sciences (India)
Danilo Calderini; Simonetta Cavalli; Cecilia Coletti; Gaia Grossi; Vincenzo Qquilanti
2012-01-01
The simple connection between the Slater orbitals, venerable in quantum chemistry, and the Coulomb Sturmian orbitals, more recently employed in atomic and molecular physics, is pointed out explicitly in view of the renewed interest in both as basis sets in applied quantum mechanics. Research in Slater orbitals mainly concerns multicentre, many-body integrals, whereas that on Sturmians exploits their orthonormality and completeness with no need of continuum states. An account of recent progress is outlined, also with reference to relationships between the two basis sets, and with the momentum space and hyperspherical harmonics representations.
Triaxiality near the 110Ru ground state from Coulomb excitation
Doherty, D. T.; Allmond, J. M.; Janssens, R. V. F.; Korten, W.; Zhu, S.; Zielińska, M.; Radford, D. C.; Ayangeakaa, A. D.; Bucher, B.; Batchelder, J. C.; Beausang, C. W.; Campbell, C.; Carpenter, M. P.; Cline, D.; Crawford, H. L.; David, H. M.; Delaroche, J. P.; Dickerson, C.; Fallon, P.; Galindo-Uribarri, A.; Kondev, F. G.; Harker, J. L.; Hayes, A. B.; Hendricks, M.; Humby, P.; Girod, M.; Gross, C. J.; Klintefjord, M.; Kolos, K.; Lane, G. J.; Lauritsen, T.; Libert, J.; Macchiavelli, A. O.; Napiorkowski, P. J.; Padilla-Rodal, E.; Pardo, R. C.; Reviol, W.; Sarantites, D. G.; Savard, G.; Seweryniak, D.; Srebrny, J.; Varner, R.; Vondrasek, R.; Wiens, A.; Wilson, E.; Wood, J. L.; Wu, C. Y.
2017-03-01
A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2 = 12 s) isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.
Analytical approach to quasiperiodic beam Coulomb field modeling
Rubtsova, I. D.
2016-09-01
The paper is devoted to modeling of space charge field of quasiperiodic axial- symmetric beam. Particle beam is simulated by charged disks. Two analytical Coulomb field expressions are presented, namely, Fourier-Bessel series and trigonometric polynomial. Both expressions permit the integral representation. It provides the possibility of integro-differential beam dynamics description. Consequently, when beam dynamics optimization problem is considered, it is possible to derive the analytical formula for quality functional gradient and to apply directed optimization methods. In addition, the paper presents the method of testing of space charge simulation code.
Hadronic correction to Coulomb potential between quarks and diquark structure
Energy Technology Data Exchange (ETDEWEB)
Xin-Heng, Guo [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Xue-Qian, Li; Peng-Nian, Shen [Academia Sinica, Beijing, BJ (China). Inst. of High Energy Physics; Chuang, Wang [Nankai Univ., TJ (China). Dept. of Physics
1997-07-01
We have studied the hadronic correction from the background pion fields due to the chiral symmetry breaking to the Coulomb potential that governs the short-distance behavior of the interactions between the bound quarks. The background fields are associated with the constituent quark mass. We find a modified form which favors the diquark structure. We also roughly estimate an influence of this correction on the phase shifts in nucleon scattering and find that it may cause an extra middle range attraction between nucleons which is expected. (author) 17 refs., 4 figs.
Coulomb interaction and first-order superconductor-insulator transition.
Syzranov, S V; Aleiner, I L; Altshuler, B L; Efetov, K B
2010-09-24
The superconductor-insulator transition (SIT) in regular arrays of Josephson junctions is studied at low temperatures. We derived an imaginary time Ginzburg-Landau-type action properly describing the Coulomb interaction. The renormalization group analysis at zero temperature T=0 in the space dimensionality d=3 shows that the SIT is always of the first order. At finite T, a tricritical point separates the lines of the first- and second-order phase transitions. The same conclusion holds for d=2 if the mutual capacitance is larger than the distance between junctions.
Quantum confinement and Coulomb blockade in isolated nanodiamond crystallites
Bolker, Asaf; Saguy, Cecile; Tordjman, Moshe; Kalish, Rafi
2013-07-01
We present direct experimental evidence of quantum confinement effects in single isolated nanodiamonds by scanning tunneling spectroscopy. For grains smaller than 4.5 nm, the band gap was found to increase with decreasing nanodiamond size and a well-defined, evenly spaced, 12-peak structure was observed on the conduction band side of the conductance curves. We attribute these peaks to the Coulomb blockade effect, reflecting the 12-fold degeneracy of the first electron-energy level in the confined nanodiamond. The present results shed light on the size dependence of the electronic properties of single nanodiamonds and are of major importance for future nanodiamond-based applications.
Optically induced structural phase transitions in ion Coulomb crystals
DEFF Research Database (Denmark)
Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael
2012-01-01
, such as body-centered cubic and face-centered cubic, can be suppressed by a proper choice of the potential depth and periodicity. Furthermore, by varying the harmonic trap parameters and/or the optical potential in time, controlled transitions between crystal structures can be obtained with close to unit......We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures...
Relation between the Fukui function and the Coulomb hole
Indian Academy of Sciences (India)
P Senet; M Yang
2005-09-01
By using a coarse-grain representation of the molecular electronic density, we demonstrate that the value of the condensed Fukui function at an atomic site is directly related to the polarization charge (Coulomb hole) induced by a test electron removed (or added) from (at) the atom. The link between the formation of an electron-hole pair and the condensed Fukui function provides insights on the possible negativity of the Fukui function which is interpreted in terms of two phenomena: overscreening and overstrengthening.
Mean Field Evolution of Fermions with Coulomb Interaction
Porta, Marcello; Rademacher, Simone; Saffirio, Chiara; Schlein, Benjamin
2017-03-01
We study the many body Schrödinger evolution of weakly coupled fermions interacting through a Coulomb potential. We are interested in a joint mean field and semiclassical scaling, that emerges naturally for initially confined particles. For initial data describing approximate Slater determinants, we prove convergence of the many-body evolution towards Hartree-Fock dynamics. Our result holds under a condition on the solution of the Hartree-Fock equation, that we can only show in a very special situation (translation invariant data, whose Hartree-Fock evolution is trivial), but that we expect to hold more generally.
Is the Coulomb sum rule violated in nuclei?
Morgenstern, J
2001-01-01
Guided by the experimental confirmation of the validity of the Effective Momentum Approximation (EMA) in quasi-elastic scattering off nuclei, we have re-examined the extraction of the longitudinal and transverse response functions in medium-weight and heavy nuclei. In the EMA we have performed a Rosenbluth separation of the available world data on $^{40}$Ca, $^{48}$Ca, $^{56}$Fe, $^{197}$Au, $^{208}$Pb and $^{238}$U. We find that the longitudinal response function for these nuclei is "quenched" and that the Coulomb sum is not saturated, at odds with claims in the literature.
"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications
Marshall, J. R.
1999-09-01
The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this
Intermediate-energy Coulomb excitation of Na30
Ettenauer, S.; Zwahlen, H.; Adrich, P.; Bazin, D.; Campbell, C. M.; Cook, J. M.; Davies, A. D.; Dinca, D.-C.; Gade, A.; Glasmacher, T.; Lecouey, J.-L.; Mueller, W. F.; Otsuka, T.; Reynolds, R. R.; Riley, L. A.; Terry, J. R.; Utsuno, Y.; Yoneda, K.
2008-07-01
The neutron-rich nucleus Na30 in the vicinity of the “Island of Inversion” was investigated using intermediate-energy Coulomb excitation. A single γ-ray transition was observed and attributed to the 31+→2gs+ decay. A transition probability of B(E2;2gs+→31+)=147(21)e2fm4 was determined and found in agreement with a previous experiment and with large-scale shell-model calculations. Evidence for the strong excitation of the 41+ state predicted by the shell-model calculations was not observed.
"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications
Marshall, J. R.
1999-01-01
The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this
Photon deflection by a Coulomb field in noncommutative QED
Energy Technology Data Exchange (ETDEWEB)
Pires, C A de S [Departamento de FIsica, Universidade Federal da ParaIba, Caixa Postal 5008, 58059-970, Joao Pessoa, PB (Brazil)
2004-12-01
In noncommutative QED photons present self-interactions in the form of triple and quartic interactions. The triple interaction implies that, even though the photon is electrically neutral, it will deflect when in the presence of an electromagnetic field. If detected, such deflection would be undoubted evidence of noncommutative space-time. In this work we derive a general expression for the deflection of a photon by any electromagnetic field. As an application we consider the case of the deflection of a photon by an external static Coulomb field. (brief report)
Photon deflection by a Coulomb field in noncommutative QED
De Pires, C A S
2004-01-01
In noncommutative QED photons present self-interactions in the form of triple and quartic interactions. The triple interaction implies that, even though the photon is electrically neutral, it will deflect when in the presence of an electromagnetic field. If detected, such deflection would be an undoubted signal of noncommutative space-time. In this work we derive the general expression for the deflection of a photon by any electromagnetic field. As an application we consider the case of the deflection of a photon by an external static Coulomb field.
Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid.
Sahin, Buyukdagli; Ralf, Blossey
2014-07-16
We study a model Coulomb fluid consisting of dipolar solvent molecules of finite extent which generalizes the point-like dipolar Poisson-Boltzmann model (DPB) previously introduced by Coalson and Duncan (1996 J. Phys. Chem. 100 2612) and Abrashkin et al (2007 Phys. Rev. Lett. 99 077801). We formulate a nonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear dielectric response in this model for the case of a single plane geometry. Our results shed light on the relevance of nonlocal versus nonlinear effects in continuum models of material electrostatics.
The distinguishable cluster approach from a screened Coulomb formalism.
Kats, Daniel
2016-01-28
The distinguishable cluster doubles equations have been derived starting from an effective screened Coulomb formalism and a particle-hole symmetric formulation of the Fock matrix. A perturbative triples correction to the distinguishable cluster with singles and doubles (DCSD) has been introduced employing the screened integrals. It is shown that the resulting DCSD(T) method is more accurate than DCSD for reaction energies and is less sensitive to the static correlation than coupled cluster with singles and doubles with a perturbative triples correction.
Coulomb Interaction in Quantum Dot with a Precessing Magnetic Field
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We study electronic transport through a quantum dot (QD) with a precessing magnetic field. By using the Keldysh nonequilibrium Green function method, formulas of local density of states (LDOS) and conductance of QD are derived self-consistently. It shows that the LDOS and conductance have obvious changes with the Coulomb blockade interaction. The intensity and angle of the magnetic field or temperatures, which reflect the mesoscopic structure of the QD are derived. The superiority of this device is that the QD can be controlled easily by the magnetic field, so it is valuable to apply in generating, manipulating and probing spin state.
Proton radiography, nuclear cross sections and multiple Coulomb scattering
Energy Technology Data Exchange (ETDEWEB)
Sjue, Sky K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-11-04
The principles behind proton radiography including multiple Coulomb scattering are discussed for a purely imaginary square well nucleus in the eikonal approximation. It is found that a very crude model can reproduce the angular dependence of the cross sections measured at 24 GeV/c. The largest differences are ~3% for the 4.56 mrad data, and ~4% for the 6.68 mrad data. The prospect of understanding how to model deterministically high-energy proton radiography over a very large range of energies is promising, but it should be tested more thoroughly.
Improving Student Understanding of Coulomb's Law and Gauss's Law
Singh, Chandralekha
2016-01-01
We discuss the development and evaluation of five research-based tutorials on Coulomb's law, superposition, symmetry and Gauss's Law to help students in the calculus-based introductory physics courses learn these concepts. We discuss the performance of students on the pre-/post-tests given before and after the tutorials in three calculus-based introductory physics courses. We also discuss the performance of students who used the tutorials and those who did not use it on a multiple-choice test which employs concepts covered in the tutorials.
Momentum-space treatment of Coulomb distortions in a multiple-scattering expansion
Energy Technology Data Exchange (ETDEWEB)
Chinn, C.R. (Physics Department, Lawrence Livermore National Laboratory, Livermore, California (USA)); Elster, C. (Department of Physics, Ohio State University, Columbus, Ohio (USA)); Thaler, R.M. (Los Alamos National Laboratory, Los Alamos, New Mexico (USA) Department of Physics, Case Western Reserve University, Cleveland, Ohio (USA))
1991-10-01
The momentum-space treatment of the Coulomb interaction within the framework of the Watson multiple-scattering expansion is derived and tested numerically. By neglecting virtual Coulomb excitations and higher-order terms, the lowest-order optical potential for proton-nucleus scattering is shown to be the sum of the convolutions of a two-body nucleon-nucleon {ital t} matrix with the nuclear density and the point Coulomb interaction with the nuclear charge density. The calculation of the optical potential, as well as the treatment of the Coulomb interaction, is performed entirely in momentum space in an exact and numerically stable procedure. Elastic-scattering observables are presented for {sup 16}O, {sup 40}Ca, and {sup 208}Pb at energies up to 500 MeV. Comparisons are made with approximate treatments of the Coulomb interaction. The interference of nonlocality effects in the nuclear optical potential with different treatments of the Coulomb interaction is investigated.
Momentum-space treatment of Coulomb distortions in a multiple-scattering expansion
Chinn, C. R.; Elster, Ch.; Thaler, R. M.
1991-10-01
The momentum-space treatment of the Coulomb interaction within the framework of the Watson multiple-scattering expansion is derived and tested numerically. By neglecting virtual Coulomb excitations and higher-order terms, the lowest-order optical potential for proton-nucleus scattering is shown to be the sum of the convolutions of a two-body nucleon-nucleon t matrix with the nuclear density and the point Coulomb interaction with the nuclear charge density. The calculation of the optical potential, as well as the treatment of the Coulomb interaction, is performed entirely in momentum space in an exact and numerically stable procedure. Elastic-scattering observables are presented for 16O, 40Ca, and 208Pb at energies up to 500 MeV. Comparisons are made with approximate treatments of the Coulomb interaction. The interference of nonlocality effects in the nuclear optical potential with different treatments of the Coulomb interaction is investigated.
Kuraev, E A; Torosyan, H T
2013-01-01
Using the Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory we obtained analytically and numerically the Coulomb corrections to the quantities of the Migdal LPM effect theory. We showed that the Coulomb corrections to the spectral bremsstrahlung rate allow completely to eliminate the discrepancy between the predictions of the LPM effect theory and its measuremens and also additionally improve the agreement between predictions of the LPM effect theory analogue for a thin target and experimental data.
Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation
Energy Technology Data Exchange (ETDEWEB)
Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others
1998-03-01
In the Coulomb excitation of {sup 155}Gd with heavy projectiles, {sup 32}S, {sup 58}Ni and {sup 90}Zr, unexpectedly large enhancement of a positive-parity side band has been observed. This enhancement could not be reproduced by a Coulomb-excitation calculation taking into account the recommended upper limits of E1 or E3 transitions, which are compiled in the whole mass region, and is proportional to the electric field accomplished in the Coulomb-scattering process. (author)
Kodera, Ryosuke
2016-01-01
We study quantized Coulomb branches of quiver gauge theories of Jordan type. We prove that the quantized Coulomb branch is isomorphic to the spherical graded Cherednik algebra in the unframed case, and is isomorphic to the spherical cyclotomic rational Cherednik algebra in the framed case. We also prove that the quantized Coulomb branch is a deformation of a subquotient of the Yangian of the affine $\\mathfrak{gl}(1)$.
Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation
Energy Technology Data Exchange (ETDEWEB)
Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others
1998-03-01
In the Coulomb excitation of {sup 155}Gd with heavy projectiles, {sup 32}S, {sup 58}Ni and {sup 90}Zr, unexpectedly large enhancement of a positive-parity side band has been observed. This enhancement could not be reproduced by a Coulomb-excitation calculation taking into account the recommended upper limits of E1 or E3 transitions, which are compiled in the whole mass region, and is proportional to the electric field accomplished in the Coulomb-scattering process. (author)
Failure Mechanism of True 2D Granular Flows
Nguyen, Cuong T; Fukagawa, R
2015-01-01
Most previous experimental investigations of two-dimensional (2D) granular column collapses have been conducted using three-dimensional (3D) granular materials in narrow horizontal channels (i.e., quasi-2D condition). Our recent research on 2D granular column collapses by using 2D granular materials (i.e., aluminum rods) has revealed results that differ markedly from those reported in the literature. We assume a 2D column with an initial height of h0 and initial width of d0, a defined as their ratio (a =h0/d0), a final height of h , and maximum run-out distance of d . The experimental data suggest that for the low a regime (a 0.65), the ratio of a to (d-d0)/d0, h0/h , or d/d0 is expressed by power-law relations. In particular, the following power-function ratios (h0/h=1.42a^2/3 and d/d0=4.30a^0.72) are proposed for every a >0.65. In contrast, the ratio (d-d0)/d0=3.25a^0.96 only holds for 0.651.5. In addition, the influence of ground contact surfaces (hard or soft beds) on the final run-out distance and destru...
Twin characterisation using 2D and 3D EBSD
Institute of Scientific and Technical Information of China (English)
M. D. NAVE; J. J. L. MULDERS; A. GHOLINIA
2005-01-01
Electron backscatter diffraction (EBSD) is a superior technique for twin characterisation due to its ability to provide highly detailed classification (by generation, system and variant) of a significant number of twins in a relatively short time. 2D EBSD is now widely used for twin characterisation and provides quite good estimates of twin volume fractions under many conditions. Nevertheless, its accuracy is limited by assumptions that have to be made due to the 2D nature of the technique. With 3D EBSD, two key assumptions are no longer required, as additional information can be derived from the 3D map. This paper compares the benefits and limitations of 2D and 3D EBSD for twin characterisation. 2D EBSD enables a larger number of twins to be mapped in a given space of time, giving better statistics. 3D EBSD provides more comprehensive twin characterisation and will be a valuable tool for validation of 2D stereological methods and microstructural models of twinning during deformation.
2D nanostructures for water purification: graphene and beyond.
Dervin, Saoirse; Dionysiou, Dionysios D; Pillai, Suresh C
2016-08-18
Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials. Recent progress in the development of nanoporous graphene based materials has generated enormous potential for water purification technologies. Progress in the development of nanoporous graphene and graphene oxide (GO) membranes, the mechanism of graphene molecular sieve action, structural design, hydrophilic nature, mechanical strength and antifouling properties and the principal challenges associated with nanopore generation are discussed in detail. Subsequently, the recent applications and performance of newly developed 2D materials such as 2D boron nitride (BN) nanosheets, graphyne, molybdenum disulfide (MoS2), tungsten chalcogenides (WS2) and titanium carbide (Ti3C2Tx) are highlighted. In addition, the challenges affecting 2D nanostructures for water purification are highlighted and their applications in the water purification industry are discussed. Though only a few 2D materials have been explored so far for water treatment applications, this emerging field of research is set to attract a great deal of attention in the near future.