A Dynamically Adaptive Arbitrary Lagrangian-Eulerian Method for Hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Anderson, R W; Pember, R B; Elliott, N S
2002-10-19
A new method that combines staggered grid Arbitrary Lagrangian-Eulerian (ALE) techniques with structured local adaptive mesh refinement (AMR) has been developed for solution of the Euler equations. The novel components of the combined ALE-AMR method hinge upon the integration of traditional AMR techniques with both staggered grid Lagrangian operators as well as elliptic relaxation operators on moving, deforming mesh hierarchies. Numerical examples demonstrate the utility of the method in performing detailed three-dimensional shock-driven instability calculations.
A Dynamically Adaptive Arbitrary Lagrangian-Eulerian Method for Hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Anderson, R W; Pember, R B; Elliott, N S
2004-01-28
A new method that combines staggered grid Arbitrary Lagrangian-Eulerian (ALE) techniques with structured local adaptive mesh refinement (AMR) has been developed for solution of the Euler equations. The novel components of the combined ALE-AMR method hinge upon the integration of traditional AMR techniques with both staggered grid Lagrangian operators as well as elliptic relaxation operators on moving, deforming mesh hierarchies. Numerical examples demonstrate the utility of the method in performing detailed three-dimensional shock-driven instability calculations.
Simulation of Steady Laser Hardening by an Arbitrary Lagrangian Eulerian Method
Geijselaers, H.J.M.; Huetink, J.
2004-01-01
One of the most practical methods for simulation of steady state thermal processing is the Arbitrary Lagrangian- Eulerian method. Each calculation step is split into two phases. In the first phase, the Lagrangian phase, the element mesh remains attached to the material. The evolution of the state va
Institute of Scientific and Technical Information of China (English)
USAMA Umer; XIE Lijing; WANG Xibin
2006-01-01
A two-dimensional finite element (FE) model for the high speed turning operations when orthogonally machining AISI H13 tool steel at 49HRC using poly crystalline cubic boron nitride(PCBN) is described. An arbitrary Lagrangian Eulerian (ALE) method has been adopted which does not need any chip separation criteria as opposed to the traditional Lagrangian approach. Through FE simulations temperature and stresses distributions are presented that could be helpful in predicting tool life and improving process parameters. The results show that high temperatures are generated along the tool rake face as compared to the shear zone temperatures due to high thermal conductivity of PCBN tools.
A Dynamically Adaptive Arbitrary Lagrangian-Eulerian Method for Solution of the Euler Equations
Energy Technology Data Exchange (ETDEWEB)
Anderson, R W; Elliott, N S; Pember, R B
2003-02-14
A new method that combines staggered grid arbitrary Lagrangian-Eulerian (ALE) techniques with structured local adaptive mesh refinement (AMR) has been developed for solution of the Euler equations. The novel components of the methods are driven by the need to reconcile traditional AMR techniques with the staggered variables and moving, deforming meshes associated with Lagrange based ALE schemes. We develop interlevel solution transfer operators and interlevel boundary conditions first in the case of purely Lagrangian hydrodynamics, and then extend these ideas into an ALE method by developing adaptive extensions of elliptic mesh relaxation techniques. Conservation properties of the method are analyzed, and a series of test problem calculations are presented which demonstrate the utility and efficiency of the method.
Simulation of sheet metal extrusion processes with Arbitrary Lagrangian-Eulerian method
Institute of Scientific and Technical Information of China (English)
ZHUANG Xin-cun; ZHAO Zhen; XIANG Hua; LI Cong-xin
2008-01-01
An Arbitrary Lagrangian-Eulerian(ALE) method was employed to simulate the sheet metal extrusion process, aiming at avoiding mesh distortion and improving the computational accuracy. The method was implemented based on MSC/MARC by using a fractional step method, i.e. a Lagrangian step followed by an Euler step. The Lagrangian step was a pure updated Lagrangian calculation and the Euler step was performed using mesh smoothing and remapping scheme. Due to the extreme distortion of deformation domain, it was almost impossible to complete the whole simulation with only one mesh topology. Therefore, global remeshing combined with the ALE method was used in the simulation work. Based on the numerical model of the process, some deformation features of the sheet metal extrusion process, such as distribution of localized equivalent plastic strain, and shrinkage cavity, were revealed. Furthermore, the differences between conventional extrusion and sheet metal extrusion process were also analyzed.
Large eddy simulation of Rayleigh-Taylor instability using the arbitrary Lagrangian-Eulerian method
Energy Technology Data Exchange (ETDEWEB)
Darlington, R
1999-12-01
This research addresses the application of a large eddy simulation (LES) to Arbitrary Lagrangian Eulerian (ALE) simulations of Rayleigh-Taylor instability. First, ALE simulations of simplified Rayleigh-Taylor instability are studied. The advantages of ALE over Eulerian simulations are shown. Next, the behavior of the LES is examined in a more complicated ALE simulation of Rayleigh-Taylor instability. The effects of eddy viscosity and stochastic backscatter are examined. The LES is also coupled with ALE to increase grid resolution in areas where it is needed. Finally, the methods studied above are applied to two sets of experimental simulations. In these simulations, ALE allows the mesh to follow expanding experimental targets, while LES can be used to mimic the effect of unresolved instability modes.
Ganesan, Sashikumaar
2014-01-01
An arbitrary Lagrangian--Eulerian (ALE) finite element scheme for computations of soluble surfactant droplet impingement on a horizontal surface is presented. The numerical scheme solves the time-dependent Navier--Stokes equations for the fluid flow, scalar convection-diffusion equation for the surfactant transport in the bulk phase, and simultaneously, surface evolution equations for the surfactants on the free surface and on the liquid-solid interface. The effects of surfactants on the flow dynamics are included into the model through the surfactant-dependent surface tension and dynamic contact angle. In particular, the dynamic contact angle of the droplet is defined as a function of surfactants using the nonlinear equation of state for surface tension. Further, the surface forces are included in the model using the Boussinesq-Scriven law that allows to incorporate the Marangoni effects without evaluating the gradients of surfactant concentration on the free surface. In addition to a mesh convergence study ...
Wu, C. S.; Young, D. L.; Chiu, C. L.
2013-12-01
This article aims to develop a Cartesian-grid-based numerical model to study the interaction between free-surface flow and stationary or oscillating immersed obstacle in a viscous fluid. To incorporate the effect of the free surface motion, an arbitrary Lagrangian-Eulerian (ALE) scheme is employed to accurately capture the configuration of free surface. To deal with the complex submerged obstacle in the fluid, a hybrid Cartesian/immersed boundary (HCIB) method is adopted, which allows easy implementation of the solid boundary conditions for a fixed structured grid. The two numerical techniques are combined to study the wave-structure interaction problems. The major merit of the proposed model is that the fluid grid is fixed throughout the computations during the transients, while the immersed body can move arbitrarily through the Cartesian grid. The meshes deform smoothly over the solid and free-surface boundaries, especially for representing sharp interface. There is no re-meshing process needed since this scheme only depends on the simple mesh generation to promote the efficiency of calculation. Some numerical examples are displayed respectively to validate the robustness and accuracy of the HCIB method, the ALE based finite-element scheme and their combinations. In addition, the other two numerical applications are carried out to simulate the wave-structure interaction with stationary and moving immersed body. In case studies some physical characteristics are also discussed for a range of amplitude of free-surface wave, Reynolds numbers and the proximity of structure under the liquid surface. The feasibility of the developed novel numerical model is shown through five numerical experiments.
An Arbitrary Lagrangian-Eulerian Discretization of MHD on 3D Unstructured Grids
Energy Technology Data Exchange (ETDEWEB)
Rieben, R N; White, D A; Wallin, B K; Solberg, J M
2006-06-12
We present an arbitrary Lagrangian-Eulerian (ALE) discretization of the equations of resistive magnetohydrodynamics (MHD) on unstructured hexahedral grids. The method is formulated using an operator-split approach with three distinct phases: electromagnetic diffusion, Lagrangian motion, and Eulerian advection. The resistive magnetic dynamo equation is discretized using a compatible mixed finite element method with a 2nd order accurate implicit time differencing scheme which preserves the divergence-free nature of the magnetic field. At each discrete time step, electromagnetic force and heat terms are calculated and coupled to the hydrodynamic equations to compute the Lagrangian motion of the conducting materials. By virtue of the compatible discretization method used, the invariants of Lagrangian MHD motion are preserved in a discrete sense. When the Lagrangian motion of the mesh causes significant distortion, that distortion is corrected with a relaxation of the mesh, followed by a 2nd order monotonic remap of the electromagnetic state variables. The remap is equivalent to Eulerian advection of the magnetic flux density with a fictitious mesh relaxation velocity. The magnetic advection is performed using a novel variant of constrained transport (CT) that is valid for unstructured hexahedral grids with arbitrary mesh velocities. The advection method maintains the divergence free nature of the magnetic field and is second order accurate in regions where the solution is sufficiently smooth. For regions in which the magnetic field is discontinuous (e.g. MHD shocks) the method is limited using a novel variant of algebraic flux correction (AFC) which is local extremum diminishing (LED) and divergence preserving. Finally, we verify each stage of the discretization via a set of numerical experiments.
Boscheri, Walter; Loubère, Raphaël; Dumbser, Michael
2015-07-01
In this paper we present a new family of efficient high order accurate direct Arbitrary-Lagrangian-Eulerian (ALE) one-step ADER-MOOD finite volume schemes for the solution of nonlinear hyperbolic systems of conservation laws for moving unstructured triangular and tetrahedral meshes. This family is the next generation of the ALE ADER-WENO schemes presented in [16,20]. Here, we use again an element-local space-time Galerkin finite element predictor method to achieve a high order accurate one-step time discretization, while the somewhat expensive WENO approach on moving meshes, used to obtain high order of accuracy in space, is replaced by an a posteriori MOOD loop which is shown to be less expensive but still as accurate. This a posteriori MOOD loop ensures the numerical solution in each cell at any discrete time level to fulfill a set of user-defined detection criteria. If a cell average does not satisfy the detection criteria, then the solution is locally re-computed by progressively decrementing the order of the polynomial reconstruction, following a so-called cascade of predefined schemes with decreasing approximation order. A so-called parachute scheme, typically a very robust first order Godunov-type finite volume method, is employed as a last resort for highly problematic cells. The cascade of schemes defines how the decrementing process is carried out, i.e. how many schemes are tried and which orders are adopted for the polynomial reconstructions. The cascade and the parachute scheme are choices of the user or the code developer. Consequently the iterative MOOD loop allows the numerical solution to maintain some interesting properties such as positivity, mesh validity, etc., which are otherwise difficult to ensure. We have applied our new high order unstructured direct ALE ADER-MOOD schemes to the multi-dimensional Euler equations of compressible gas dynamics. A large set of test problems has been simulated and analyzed to assess the validity of our approach
Sahin, Mehmet
2010-01-01
A new geometrically conservative arbitrary Lagrangian-Eulerian (ALE) formulation is presented for the moving boundary problems in the swirl-free cylindrical coordinates. The governing equations are multiplied with the radial distance and integrated over arbitrary moving Lagrangian-Eulerian quadrilateral elements. Therefore, the continuity and the geometric conservation equations take very simple form similar to those of the Cartesian coordinates. The continuity equation is satisfied exactly within each element and a special attention is given to satisfy the geometric conservation law (GCL) at the discrete level. The equation of motion of a deforming body is solved in addition to the Navier-Stokes equations in a fully-coupled form. The mesh deformation is achieved by solving the linear elasticity equation at each time level while avoiding remeshing in order to enhance numerical robustness. The resulting algebraic linear systems are solved using an ILU(k) preconditioned GMRES method provided by the PETSc librar...
A Methodology to Validate 3-D Arbitrary Lagrangian Eulerian Codes with Applications to Alegra
Energy Technology Data Exchange (ETDEWEB)
Chhabildas, L.C.; Duggins, B.D.; Konrad, C.H.; Mosher, D.A.; Perry, J.S.; Reinhart, W.D.; Summers, R.M.; Trucano, T.G.
1998-11-04
In this study we provided an experimental test bed for validating features of the Arbitrary Lagrangian Eulerian Grid for Research Applications (ALEGRA) code over a broad range of strain rates with overlapping diagnostics that encompass the multiple responses. A unique feature of the ALEGRA code is that it allows simultaneous computational treatment, within one code, of a wide range of strain-rates varying from hydrodynamic to structural conditions. This range encompasses strain rates characteristic of shock-wave propagation (107/s) and those characteristics of structural response (102/s). Most previous code validation experimental &udies, however, have been restricted to simulating or investigating a single strain-rate regime. What is new and different in this investigation is that we have performed well-controlled and well-instrumented experiments, which capture features relevant to both hydrodynamic and structural response in a single experiment. Aluminum was chosen for use in this study because it is a well-characterized material. The current experiments span strain rate regimes of over 107/s to less than 102/s in a single experiment. The input conditions were extremely well defined. Velocity interferometers were used to record the high' strain-rate response, while low strain rate data were collected using strain gauges. Although the current tests were conducted at a nominal velocity of - 1.5 km/s, it is the test methodology that is being emphasized herein. Results of a three-dimensional experiment are also presented.
Su, Xiaohui; Cao, Yuanwei; Zhao, Yong
2016-06-01
In this paper, an unstructured mesh Arbitrary Lagrangian-Eulerian (ALE) incompressible flow solver is developed to investigate the aerodynamics of insect hovering flight. The proposed finite-volume ALE Navier-Stokes solver is based on the artificial compressibility method (ACM) with a high-resolution method of characteristics-based scheme on unstructured grids. The present ALE model is validated and assessed through flow passing over an oscillating cylinder. Good agreements with experimental results and other numerical solutions are obtained, which demonstrates the accuracy and the capability of the present model. The lift generation mechanisms of 2D wing in hovering motion, including wake capture, delayed stall, rapid pitch, as well as clap and fling are then studied and illustrated using the current ALE model. Moreover, the optimized angular amplitude in symmetry model, 45°, is firstly reported in details using averaged lift and the energy power method. Besides, the lift generation of complete cyclic clap and fling motion, which is simulated by few researchers using the ALE method due to large deformation, is studied and clarified for the first time. The present ALE model is found to be a useful tool to investigate lift force generation mechanism for insect wing flight.
Gaston, Laurence; Kamara, Alima; Bellet, Michel
2000-01-01
This is the pre-peer reviewed version of the following article : An arbitrary Lagrangian-Eulerian finite element approach to non-steady state turbulent fluid flow with application to mould filling in casting, Gaston L., Kamara A., Bellet M. International Journal for Numerical Methods in Fluids 34, 4 (2000) pages 341-369, which has been published in final form at http://dx.doi.org/10.1002/1097-0363(20001030)34:4%3C341::AID-FLD64%3E3.0.CO;2-K International audience This paper presents a t...
Melis, Matthew E.
2003-01-01
Explicit finite element techniques employing an Arbitrary Lagrangian-Eulerian (ALE) methodology, within the transient dynamic code LS-DYNA, are used to predict splashdown loads on a proposed replacement/upgrade of the hydrazine tanks on the thrust vector control system housed within the aft skirt of a Space Shuttle Solid Rocket Booster. Two preliminary studies are performed prior to the full aft skirt analysis: An analysis of the proposed tank impacting water without supporting aft skirt structure, and an analysis of space capsule water drop tests conducted at NASA's Langley Research Center. Results from the preliminary studies provide confidence that useful predictions can be made by applying the ALE methodology to a detailed analysis of a 26-degree section of the skirt with proposed tank attached. Results for all three studies are presented and compared to limited experimental data. The challenges of using the LS-DYNA ALE capability for this type of analysis are discussed.
On the integration of the arbitrary Lagrangian-Eulerian concept and non-equilibrium thermodynamics
Knobbe, E.M.
2010-01-01
The aim of this treatise is to present a harmonious mathematical formulation of an explicit moving mesh method that can be used as a basis for many numerical techniques. In most cases a moving mesh is only used to include arbitrary motions and deformations of a geometry into the simulation of a phys
On the integration of the arbitrary Lagrangian-Eulerian concept and non-equilibrium thermodynamics
Knobbe, E.M.
2010-01-01
The aim of this treatise is to present a harmonious mathematical formulation of an explicit moving mesh method that can be used as a basis for many numerical techniques. In most cases a moving mesh is only used to include arbitrary motions and deformations of a geometry into the simulation of a physical problem. The innovative part of this research is to develop a mechanism that controls the motion of interior mesh points by detecting and tracking the location of physical phenomena. The motio...
Acoustic Streaming: An Arbitrary Lagrangian-Eulerian Perspective
Nama, Nitesh; Costanzo, Francesco
2016-01-01
We analyze acoustic streaming flows using an ALE perspective. The formulation stems from an explicit separation of time-scales resulting in two subproblems: a first-order problem, formulated in terms of the fluid displacement at the fast scale, and a second-order problem formulated in terms of the Lagrangian flow velocity at the slow time scale. Following a rigorous time-averaging procedure, the second-order problem is shown to be intrinsically steady, and with exact boundary conditions at the oscillating walls. Also, as the second-order problem is solved directly for the Lagrangian velocity, the formulation does not need to employ the notion of Stokes drift, or any associated post-processing, thus facilitating a direct comparison with experiments. Because the first-order problem is formulated in terms of the displacement field, our formulation is directly applicable to more complex fluid-structure interaction problems in microacosutofluidic devices. After the formulation's exposition, we present numerical re...
Arbitrary lagrangian-eulerian formulation of quasistatic nonlinear problems
Rodríguez Ferran, Antonio
1996-01-01
En esta tesis se presenta una metodología para la simulación numérica de procesos cuasistaticos en mecánica de sólidos no lineal, basada en una formulación arbitrariamente lagrangiana-euleriana (ale) del problema. Se hace un enfoque generalista, que abarca algunas cuestiones fundamentales en mecánica computacional y en análisis numérico: la resolución de sistemas no lineales de ecuaciones algebraicas y la integración de las ecuaciones constitutivas no lineales. Como entorno de trabajo se util...
Energy Technology Data Exchange (ETDEWEB)
Ames, Thomas L.; Farnsworth, Grant V.; Ketcheson, David Isaac; Robinson, Allen Conrad
2009-09-01
The modeling of solids is most naturally placed within a Lagrangian framework because it requires constitutive models which depend on knowledge of the original material orientations and subsequent deformations. Detailed kinematic information is needed to ensure material frame indifference which is captured through the deformation gradient F. Such information can be tracked easily in a Lagrangian code. Unfortunately, not all problems can be easily modeled using Lagrangian concepts due to severe distortions in the underlying motion. Either a Lagrangian/Eulerian or a pure Eulerian modeling framework must be introduced. We discuss and contrast several Lagrangian/Eulerian approaches for keeping track of the details of material kinematics.
A hybrid Lagrangian-Eulerian numerical model for sea-ice dynamics
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A hybrid Lagrangian-Eulerian (HLE) method is developed for sea ice dynamics, which combines the high computational efficiency of finite difference method (FDM) with the high numerical accuracy of smoothed particle hydrodynamics (SPH). In this HLE model, the sea ice cover is represented by a group of Lagrangian ice particles with their own thicknesses and concentrations. These ice variables are interpolated to the Eularian gird nodes using the Gaussian interpolation function. The FDM is used to determine the ice velocities at Eulerian grid nodes, and the velocities of Lagrangian ice particles are interpolated from these grid velocities with the Gaussian function also. The thicknesses and concentrations of ice particles are determined based on their new locations. With the HLE numerical model, the ice ridging process in a rectangular basin is simulated, and the simulated results are validated with the analytical solution. This method is also applied to the simulation of sea ice dynamics in a vortex wind field. At last, this HLE model is applied to the Bohai Sea, and the simulated concentration, thickness and velocity match the satellite images and the field observed data well.
Mesh update techniques for free-surface flow solvers using spectral element method
Bouffanais, Roland; Deville, Michel O.
2007-01-01
This paper presents a novel mesh-update technique for unsteady free-surface Newtonian flows using spectral element method and relying on the arbitrary Lagrangian--Eulerian kinematic description for moving the grid. Selected results showing compatibility of this mesh-update technique with spectral element method are given.
A finite-element method model for droplets moving down a hydrophobic surface
DEFF Research Database (Denmark)
Wind-Willassen, Øistein; Sørensen, Mads Peter
2014-01-01
We set up a 2D computational Finite-Element Method (FEM) model describing the initial descent of a droplet down an inclined hydrophobic substrate. We solve the full Navier-Stokes equations inside the drop domain, and use the arbitrary Lagrangian-Eulerian method to keep track of the droplet surface...
Andreussi, T; Pegoraro, F
2016-01-01
Because different constraints are imposed, stability conditions for dissipationless fluids and magnetofluids may take different forms when derived within the Lagrangian, Eulerian (energy-Casimir), or dynamical accessible frameworks. This is in particular the case when flows are present. These differences are explored explicitly by working out in detail two magnetohydrodynamic examples: convection against gravity in a stratified fluid and translationally invariant perturbations of a rotating magnetized plasma pinch. In this second example we show in explicit form how to perform the time-dependent relabeling introduced in Andreussi {\\it et al.}\\ [Phys.\\ Plasmas {\\bf20}, 092104 (2013)] that makes it possible to reformulate Eulerian equilibria with flows as Lagrangian equilibria in the relabeled variables. The procedures detailed in the present article provide a paradigm that can be applied to more general plasma configurations and in addition extended to more general plasma descriptions where dissipation is abse...
International Nuclear Information System (INIS)
An algebraic mistake in the rendering of the Energy Casimir stability condition for a symmetric magnetohydrodynamics plasma configuration with flows made in the article Andreussi et al. “Hamiltonian magnetohydrodynamics: Lagrangian, Eulerian, and dynamically accessible stability—Theory,” Phys. Plasmas 20, 092104 (2013) is corrected
Institute of Scientific and Technical Information of China (English)
杨吉忠; 毕海权; 翟婉明
2009-01-01
利用有限体积法对横风作用下列车周围的空气流场进行计算.结合车辆-轨道耦合动力学,采用任意拉格朗日-欧拉(ALE)方法处理列车与空气间存在的运动边界,实现了车辆系统动力学与计算流体力学之间的结合.以某国产客运列车为例,计算列车在20 m/s的横风作用下以160 km/h的速度运行时的动力学响应,给出列车周围的流场分布;分析了考虑与不考虑风-车之间流固耦合效应时,作用在车辆上的气动力和气动力矩的变化情况.结果表明,流固耦合效应对车体摇头力矩的影响比较大,而对于车体垂向、横向位移和加速度的影响甚微.
International Nuclear Information System (INIS)
The computer program LEHGC is a Hybrid Lagrangian-Eulerian Finite-Element Model of HydroGeo-Chemical (LEHGC) Transport Through Saturated-Unsaturated Media. LEHGC iteratively solves two-dimensional transport and geochemical equilibrium equations and is a descendant of HYDROGEOCHEM, a strictly Eulerian finite-element reactive transport code. The hybrid Lagrangian-Eulerian scheme improves on the Eulerian scheme by allowing larger time steps to be used in the advection-dominant transport calculations. This causes less numerical dispersion and alleviates the problem of calculated negative concentrations at sharp concentration fronts. The code also is more computationally efficient than the strictly Eulerian version. LEHGC is designed for generic application to reactive transport problems associated with contaminant transport in subsurface media. Input to the program includes the geometry of the system, the spatial distribution of finite elements and nodes, the properties of the media, the potential chemical reactions, and the initial and boundary conditions. Output includes the spatial distribution of chemical element concentrations as a function of time and space and the chemical speciation at user-specified nodes. LEHGC Version 1.1 is a modification of LEHGC Version 1.0. The modification includes: (1) devising a tracking algorithm with the computational effort proportional to N where N is the number of computational grid nodes rather than N2 as in LEHGC Version 1.0, (2) including multiple adsorbing sites and multiple ion-exchange sites, (3) using four preconditioned conjugate gradient methods for the solution of matrix equations, and (4) providing a model for some features of solute transport by colloids
Dhir, Gaurav; Suman, Sawan
2015-11-01
Experimental evidence shows that aircrafts operating under heavy rainfall conditions face deterioration of lift and increase in drag. This scenario can be a critical design challenge especially for slow moving vehicles such as airships. Effective roughening of airfoil surface caused by an uneven water film, loss of flow momentum and the loss of vehicle momentum due to its collision with the raindrops are the primary reasons causing the drag to increase. Our work focuses primarily on the numerical quantification of boundary layer momentum loss caused due to raindrops. The collision of raindrops with a solid surface leads to formation of an ejecta fog of splashed back droplets with their sizes being of the order of micrometers and their acceleration leads to boundary layer momentum loss. We model the airflow within a flat plate boundary layer using a Lagrangian-Eulerian approach with the raindrops being considered as non-deformable, non-spinning and non-interacting droplets. We employ an inter-phase coupling term to account for the interaction between the boundary layer flow and the droplets. Our presentation will focus on several comparisons (velocity field, lift and drag at various angles of attack) with the results of the standard (rain-free) Prandtl boundary layer flow. Indian Institute of Technology, Delhi.
A New Method to Simulate Free Surface Flows for Viscoelastic Fluid
Yu Cao; Xiao-Guang Ren; Xiao-Wei Guo; Miao Wang; Qian Wang; Xin-Hai Xu; Xue-Jun Yang
2015-01-01
Free surface flows arise in a variety of engineering applications. To predict the dynamic characteristics of such problems, specific numerical methods are required to accurately capture the shape of free surface. This paper proposed a new method which combined the Arbitrary Lagrangian-Eulerian (ALE) technique with the Finite Volume Method (FVM) to simulate the time-dependent viscoelastic free surface flows. Based on an open source CFD toolbox called OpenFOAM, we designed an ALE-FVM free surfa...
Heckmann, Andreas; Hartweg, Stefan; Kaiser, Ingo
2011-01-01
The bending deformation of rotating annular plates and the associated vibration behaviour is important in engineering applications which range from automotive or railway brake systems to discs that form essential components in turbomachinery. In order to extend the capabilities of the DLR FlexibleBodies library for such use cases, a new Modelica class has been implemented which is based on the analytical description of an annular Kirchhoff plate. In addition the so-called Arbitray Langra...
GO++ : A modular Lagrangian/Eulerian software for Hamilton Jacobi equations of Geometric Optics type
Benamou, Jean-David; Hoch, Philippe
2002-01-01
We describe both the classical Lagrangian and the Eulerian methods for first order Hamilton-Jacobi equations of geometric optic type. We then explain the basic structure of the software and how new solvers/models can be added to it. A selection of numerical examples presented.Hamilton-Jacobi,Hamiltonian System, Ray Tracing, Viscosity Solution, Upwind Scheme, Geometric Optics, C++
ALE Fractional Step Finite Element Method for Fluid-Structure Nonlinear Interaction Problem
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A computational procedure is developed to solve the problems of coupled motion of a structure and a viscous incompressible fluid. In order to incorporate the effect of the moving surface of the structure as well as the free surface motion, the arbitrary Lagrangian-Eulerian formulation is employed as the basis of the finite element spatial discretization. For numerical integration in time, the fraction step method is used. This method is useful because one can use the same linear interpolation function for both velocity and pressure. The method is applied to the nonlinear interaction of a structure and a tuned liquid damper. All computations are performed with a personal computer.
Siqueira, Mario; Lai, Chun-Ta; Katul, Gabriel
2000-12-01
A new method was developed to estimate canopy sources and sinks from measured mean concentration profiles within the canopy (referred to as the ``inverse'' problem). The proposed method combined many of the practical advantages of the Lagrangian localized near-field (LNF) theory and higher-order Eulerian (EUL) closure principles. Particularly, this ``hybrid'' method successfully combined the essential conservation equations of closure modeling and the robustness of the regression source inversion developed for LNF theory. The proposed method along with LNF and EUL were tested using measurements from two field experiments collected in a pine forest and published measurements from a wind tunnel experiment. The field experiments were conducted to investigate the vertical distribution of the scalar fluxes within the canopy and the temporal patterns of the scalar fluxes above the canopy. This comparison constitutes the first ``inverse method'' comparison performed using the same data sets on all three models. For the wind tunnel data, all three models well reproduced the measured flux distribution. For the field experiments, all three models recovered the measured spatial and temporal flux distribution in an ensemble sense. The agreement between these three models is desirable to the inverse problem because it adds the necessary confidence in the computed flux distributions. However, the agreement among all three models with the field measurements, on a 30-min time step, was less than satisfactory. Additionally, the divergence between models and measurements increased with departure from a near-neutral atmospheric state. Despite fundamental differences in these model approximations, this similarity in model performance suggests that the source information recovered from a measured one-dimensional mean concentration profile will not be further enhanced by a one-dimensional steady state, planar homogeneous model of neutral flows.
Simulation of extrudate swell using an extended finite element method
Choi, Young Joon; Hulsen, Martien A.
2011-09-01
An extended finite element method (XFEM) is presented for the simulation of extrudate swell. A temporary arbitrary Lagrangian-Eulerian (ALE) scheme is incorporated to cope with the movement of the free surface. The main advantage of the proposed method is that the movement of the free surface can be simulated on a fixed Eulerian mesh without any need of re-meshing. The swell ratio of an upper-convected Maxwell fluid is compared with those of the moving boundary-fitted mesh problems of the conventional ALE technique, and those of Crochet & Keunings (1980). The proposed XFEM combined with the temporary ALE scheme can provide similar accuracy to the boundary-fitted mesh problems for low Deborah numbers. For high Deborah numbers, the method seems to be more stable for the extrusion problem.
A New Method to Simulate Free Surface Flows for Viscoelastic Fluid
Directory of Open Access Journals (Sweden)
Yu Cao
2015-01-01
Full Text Available Free surface flows arise in a variety of engineering applications. To predict the dynamic characteristics of such problems, specific numerical methods are required to accurately capture the shape of free surface. This paper proposed a new method which combined the Arbitrary Lagrangian-Eulerian (ALE technique with the Finite Volume Method (FVM to simulate the time-dependent viscoelastic free surface flows. Based on an open source CFD toolbox called OpenFOAM, we designed an ALE-FVM free surface simulation platform. In the meantime, the die-swell flow had been investigated with our proposed platform to make a further analysis of free surface phenomenon. The results validated the correctness and effectiveness of the proposed method for free surface simulation in both Newtonian fluid and viscoelastic fluid.
Methods for simulation-based analysis of fluid-structure interaction.
Energy Technology Data Exchange (ETDEWEB)
Barone, Matthew Franklin; Payne, Jeffrey L.
2005-10-01
Methods for analysis of fluid-structure interaction using high fidelity simulations are critically reviewed. First, a literature review of modern numerical techniques for simulation of aeroelastic phenomena is presented. The review focuses on methods contained within the arbitrary Lagrangian-Eulerian (ALE) framework for coupling computational fluid dynamics codes to computational structural mechanics codes. The review treats mesh movement algorithms, the role of the geometric conservation law, time advancement schemes, wetted surface interface strategies, and some representative applications. The complexity and computational expense of coupled Navier-Stokes/structural dynamics simulations points to the need for reduced order modeling to facilitate parametric analysis. The proper orthogonal decomposition (POD)/Galerkin projection approach for building a reduced order model (ROM) is presented, along with ideas for extension of the methodology to allow construction of ROMs based on data generated from ALE simulations.
A NUMERICAL METHOD FOR SIMULATING NONLINEAR FLUID-RIGID STRUCTURE INTERACTION PROBLEMS
Institute of Scientific and Technical Information of China (English)
XingJ.T; PriceW.G; ChenY.G
2005-01-01
A numerical method for simulating nonlinear fluid-rigid structure interaction problems is developed. The structure is assumed to undergo large rigid body motions and the fluid flow is governed by nonlinear, viscous or non-viscous, field equations with nonlinear boundary conditions applied to the free surface and fluid-solid interaction interfaces. An Arbitrary-Lagrangian-Eulerian (ALE) mesh system is used to construct the numerical model. A multi-block numerical scheme of study is adopted allowing for the relative motion between moving overset grids, which are independent of one another. This provides a convenient method to overcome the difficulties in matching fluid meshes with large solid motions. Nonlinear numerical equations describing nonlinear fluid-solid interaction dynamics are derived through a numerical discretization scheme of study. A coupling iteration process is used to solve these numerical equations. Numerical examples are presented to demonstrate applications of the model developed.
International Nuclear Information System (INIS)
We introduce and study numerically a scalable parallel finite element solver for the simulation of blood flow in compliant arteries. The incompressible Navier-Stokes equations are used to model the fluid and coupled to an incompressible linear elastic model for the blood vessel walls. Our method features an unstructured dynamic mesh capable of modeling complicated geometries, an arbitrary Lagrangian-Eulerian framework that allows for large displacements of the moving fluid domain, monolithic coupling between the fluid and structure equations, and fully implicit time discretization. Simulations based on blood vessel geometries derived from patient-specific clinical data are performed on large supercomputers using scalable Newton-Krylov algorithms preconditioned with an overlapping restricted additive Schwarz method that preconditions the entire fluid-structure system together. The algorithm is shown to be robust and scalable for a variety of physical parameters, scaling to hundreds of processors and millions of unknowns.
AbuAlSaud, Moataz
2012-07-01
The purpose of this thesis is to solve unsteady two-dimensional compressible Navier-Stokes equations for a moving mesh using implicit explicit (IMEX) Runge- Kutta scheme. The moving mesh is implemented in the equations using Arbitrary Lagrangian Eulerian (ALE) formulation. The inviscid part of the equation is explicitly solved using second-order Godunov method, whereas the viscous part is calculated implicitly. We simulate subsonic compressible flow over static NACA-0012 airfoil at different angle of attacks. Finally, the moving mesh is examined via oscillating the airfoil between angle of attack = 0 and = 20 harmonically. It is observed that the numerical solution matches the experimental and numerical results in the literature to within 20%.
A general topology, Godunov method
Energy Technology Data Exchange (ETDEWEB)
Addessio, F.; Cline, M.; Dukowicz, J.
1987-01-01
A numerical technique that utilizes a general topology mesh is described. The method employs the arbitrary Lagrangian-Eulerian procedure and explicit, finite-volume, Godunov numerics. Material interfaces are resolved to eliminate fictitious mixing and nonphysical shear impedance. Cell-centered variables, including velocity, are used to provide consistent control volumes for the advection of mass, momentum, and energy, and to allow arbitrary slip between material regions. The computational mesh is composed of arbitrary polygonal cells. The constraint of a fixed logical connectivity for the mesh is removed. Consequently, geometrical mesh limitations, which are responsible for inaccuracies and code failure during the evolution of region boundaries, are absent. Arbitrary boundaries can be resolved, and the mesh is capable of changing smoothly and rapidly from regions of high to low resolution. Lack of a coherent mesh orientation minimizes numerical anisotropy. A mesh rezoning approach, based on a dual triangulation and coupled with a global remapping algorithm, allows the mesh to evolve dynamically. 9 refs., 6 figs.
Method of Direct Texture Synthesis on Arbitrary Surfaces
Institute of Scientific and Technical Information of China (English)
Fu-Li Wu; Chun-Hui Mei; Jiao-Ying Shi
2004-01-01
A direct texture synthesis method on arbitrary surfaces is proposed in this paper. The idea is to recursively map triangles on surface to texture space until the surface is completely mapped. First, the surface is simplified and a tangential vector field is created over the simplified mesh. Then, mapping process searches for the most optimal texture coordinates in texture sample for each triangle, and the textures of neighboring triangles are blended on the mesh. All synthesized texture triangles are compressed to an atlas. Finally, the simplified mesh is subdivided to approach the initial surface. The algorithm has several advantages over former methods:it synthesizes texture on surface without local parameterization; it does not need partitioning surface to patches;and it does not need a particular texture sample. The results demonstrate that the new algorithm is applicable to a wide variety of texture samples and any triangulated surfaces.
An Efficient Grid Generation Method for Arbitrary Domains
Orme, Melissa; Huang, Changzheng
1997-11-01
This paper describes an efficient grid generation method for arbitrary or multiply connected domains. Our method, essentially based on the edge swapping techniques, combines the advantages of the Delaunay triangulation method and the advancing front method. The latter two methods are in popular use nowadays. But both suffer some limitations. Delaunay method generates high quality grid but grid may cut across the boundary in concave regions. Advancing front method works for general domain but may encounter difficulties where fronts have to be merged. The current method garantees the boundary integrity and attains the nice Delaunay features into the domain. This is achieved by carefully documenting the grid information so that each edge is readily identified to be inside or outside the domain; and (2) continuously swapping out those bad edges that destroy the Delaunay properties. The computer program built on this method allows users to control the grid density distribution by specifying typical grid sizes on a few chosen points. Interesting examples are demonstrated here. One of them is a circular domain with three letters APS inside. (see figure 1 and figure 2 ). Given a grid size for APS and another size for the circle, the program automatically generates a smooth triangular grid regardless of the complex multiply connected geometry.
Multi-scale Godunov-type method for cell-centered discrete Lagrangian hydrodynamics.
Maire, Pierre-Henri; Nkonga, Boniface
2009-01-01
This work presents a multidimensional cell-centered unstructured finite volume scheme for the solution of multimaterial compressible fluid flows written in the Lagrangian formalism. This formulation is considered in the Arbitrary-Lagrangian-Eulerian (ALE) framework with the constraint that the mesh and the fluid velocity coincide. The link between the vertex velocity and the fluid motion is obtained by a formulation of the momentum conservation on a class of multi-scale encased volumes around...
Institute of Scientific and Technical Information of China (English)
HUANG Deshuang; CHI Zheru
2004-01-01
This paper proposes a novel recursive partitioning method based on constrained learning neural networks to find an arbitrary number (less than the order of the polynomial) of (real or complex) roots of arbitrary polynomials. Moreover, this paper also gives a BP network constrained learning algorithm (CLA) used in root-finders based on the constrained relations between the roots and the coefficients of polynomials. At the same time, an adaptive selection method for the parameter δPwith the CLA is also given.The experimental results demonstrate that this method can more rapidly and effectively obtain the roots of arbitrary high order polynomials with higher precision than traditional root-finding approaches.
CIP/multi-moment finite volume method with arbitrary order of accuracy
XIAO, FENG; Ii, Satoshi
2012-01-01
This paper presents a general formulation of the CIP/multi-moment finite volume method (CIP/MM FVM) for arbitrary order of accuracy. Reconstruction up to arbitrary order can be built on single cell by adding extra derivative moments at the cell boundary. The volume integrated average (VIA) is updated via a flux-form finite volume formulation, whereas the point-based derivative moments are computed as local derivative Riemann problems by either direct interpolation or approximate Riemann solvers.
Zeng, X.; Scovazzi, G.
2016-06-01
We present a monolithic arbitrary Lagrangian-Eulerian (ALE) finite element method for computing highly transient flows with strong shocks. We use a variational multiscale (VMS) approach to stabilize a piecewise-linear Galerkin formulation of the equations of compressible flows, and an entropy artificial viscosity to capture strong solution discontinuities. Our work demonstrates the feasibility of VMS methods for highly transient shock flows, an area of research for which the VMS literature is extremely scarce. In addition, the proposed monolithic ALE method is an alternative to the more commonly used Lagrangian+remap methods, in which, at each time step, a Lagrangian computation is followed by mesh smoothing and remap (conservative solution interpolation). Lagrangian+remap methods are the methods of choice in shock hydrodynamics computations because they provide nearly optimal mesh resolution in proximity of shock fronts. However, Lagrangian+remap methods are not well suited for imposing inflow and outflow boundary conditions. These issues offer an additional motivation for the proposed approach, in which we first perform the mesh motion, and then the flow computations using the monolithic ALE framework. The proposed method is second-order accurate and stable, as demonstrated by extensive numerical examples in two and three space dimensions.
Cheap arbitrary high order methods for single integrand SDEs
DEFF Research Database (Denmark)
Debrabant, Kristian; Kværnø, Anne
2016-01-01
For a particular class of Stratonovich SDE problems, here denoted as single integrand SDEs, we prove that by applying a deterministic Runge-Kutta method of order $p_d$ we obtain methods converging in the mean-square and weak sense with order $\\lfloor p_d/2\\rfloor$. The reason is that the B...
A new method of broadband constant beamwidth beamforming for arbitrary geometry arrays
Institute of Scientific and Technical Information of China (English)
YANG Yixin; SUN Chao; LI Bin
2001-01-01
A new method of broadband constant beamwidth beamforming for arbitrary geometry arrays is proposed. In this method, the response vector of an arbitrary geometry array is expanded into the form of sum of an infinite series, whose core function is the first kind Bessel function. The high terms of this series are truncated so that the array response vectors at different frequencies can be transformed to a reference frequency arid then the constant beamwidth beamforming vectors are ready to obtain. With these beamforming vectors, beams at different frequencies are same as the reference beam. A reference beam optimizing method based on adaptive processing is also proposed to optimize the reference beam of arbitrary geometry arrays. Computer simulation for a uniform circular array verified the effectiveness of the new method proposed.
On the Arbitrary Difference Precise Integration Method and Its Numerical Stability
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Based on the subdomain precise integration method, the arbitrary difference precise integration method (ADPIM) is presented to solve PDEs. While retaining all the merits of the former method, ADPIM also demonstrates advantages such as the abilities of better description of physical properties of inhomogeneous media and convenient treatment of various boundary conditions. The explicit integration schemes derived by ADPIM are proved unconditionally stable.
Compressive VOF method with skewness correction to capture sharp interfaces on arbitrary meshes
Denner, Fabian; van Wachem, Berend G. M.
2014-12-01
The accurate and efficient modelling of two-phase flows is at present mostly limited to structured, unskewed meshes, due to the additional topological and numerical complexity of arbitrary, unstructured meshes. Compressive VOF methods which discretize the interface advection with algebraic differencing schemes are computationally efficient and inherently applicable to arbitrary meshes. However, compressive VOF methods evidently suffer severely from numerical diffusion on meshes with topological skewness. In this paper we present a compressive VOF method using a state-of-the-art donor-acceptor advection scheme which includes novel modifications to substantially reduce numerical diffusion on arbitrary meshes without adding computational complexity. The new methodology accurately captures evolving interfaces on any arbitrary, non-overlapping mesh and conserves mass within the limits of the applied solver tolerance. A thorough validation of the presented methods is conducted, examining the pure advection of the interface indicator function as well as the application to evolving interfaces with surface tension. Crucially, the results on equidistant Cartesian and arbitrary tetrahedral meshes are shown to be comparable and accurate.
Institute of Scientific and Technical Information of China (English)
CHENG Min; TANG Tiantong; YAO Zhenhua; ZHU Jingping
2001-01-01
Differential algebraic method is apowerful technique in computer numerical analysisbased on nonstandard analysis and formal series the-ory. It can compute arbitrary high order derivativeswith excellent accuracy. The principle of differentialalgebraic method is applied to calculate high orderaberrations of combined electromagnetic focusing sys-tems. As an example, third-order geometric aberra-tion coefficients of an actual combined electromagneticfocusing system were calculated. The arbitrary highorder aberrations are conveniently calculated by dif-ferential algebraic method and the fifth-order aberra-tion diagrams are given.
Numerical Method for Determining Stiffness Characteristics of an Arbitrary Form Superelement
Directory of Open Access Journals (Sweden)
Tsybenko Alexander
2015-12-01
Full Text Available As part of the superelement approximation technology for fragments (subsystems of the analyzed structures, a numerical method of determining the characteristics of arbitrary type superelements was developed. The examples of simulation models with two-node superelements demonstrated the efficacy of the method in the structural analysis of elastic systems.
Simulating Space Capsule Water Landing with Explicit Finite Element Method
Wang, John T.; Lyle, Karen H.
2007-01-01
A study of using an explicit nonlinear dynamic finite element code for simulating the water landing of a space capsule was performed. The finite element model contains Lagrangian shell elements for the space capsule and Eulerian solid elements for the water and air. An Arbitrary Lagrangian Eulerian (ALE) solver and a penalty coupling method were used for predicting the fluid and structure interaction forces. The space capsule was first assumed to be rigid, so the numerical results could be correlated with closed form solutions. The water and air meshes were continuously refined until the solution was converged. The converged maximum deceleration predicted is bounded by the classical von Karman and Wagner solutions and is considered to be an adequate solution. The refined water and air meshes were then used in the models for simulating the water landing of a capsule model that has a flexible bottom. For small pitch angle cases, the maximum deceleration from the flexible capsule model was found to be significantly greater than the maximum deceleration obtained from the corresponding rigid model. For large pitch angle cases, the difference between the maximum deceleration of the flexible model and that of its corresponding rigid model is smaller. Test data of Apollo space capsules with a flexible heat shield qualitatively support the findings presented in this paper.
Method to calculate interior sound field of arbitrary-shaped closed thin shell
Institute of Scientific and Technical Information of China (English)
WU Jiuhui; CHEN Hualing; HU Xuanli
2001-01-01
The concept of covering-domain means that an arbitrary-shaped closed shell can be approached by a series of closed spherical shells. Based on it, the interior scattering sound field of the arbitrary-shaped closed shell is given. According to the reciprocity theory, the radiating sound field of the elastic surface due to the action of external force is presented. The method presented can also be used to calculate the interior sound fields of arbitraryshaped closed thin shells of which the thickness are either equal or unequal. It is verified to be correct by corresponding test.
A New Method for Locating Calculation of Arbitrary Spatial Straight Line or Plane in NC Machining
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
In the manufacturing process, we often encounter so me location machining of space arbitrary straight lines and planes that are not on ly unparalleled but also not vertical with the machine tool spindle or the cutti ng tool. In the past, we can do the location machining through the methods of dr awing line and making level in the ordinary machine tool. In the numerical contr ol machining of the CNC machine tool and manufacturing center, however, the spac e location and angle of the arbitrary straight lines...
Hybrid Iteration Method for Fixed Points of Nonexpansive Mappings in Arbitrary Banach Spaces
Directory of Open Access Journals (Sweden)
P. U. Nwokoro
2008-02-01
Full Text Available We prove that recent results of Wang (2007 concerning the iterative approximation of fixed points of nonexpansive mappings using a hybrid iteration method in Hilbert spaces can be extended to arbitrary Banach spaces without the strong monotonicity assumption imposed on the hybrid operator.
A New Pseudospectral Method for Calculations of Hydrogen Atom in Arbitrary External Fields
Institute of Scientific and Technical Information of China (English)
QIAO Hao-Xue; LI Bai-Wen1
2002-01-01
A new pseudospectral method was introduced to calculate wavefunctions and energy levels of hydrogen atom in arbitrary potential. Some results of hydrogen atom in uniform magnetic fields were presented, high accuracy of results was obtained with simple calculations, and our calculations show very fast convergence. It suggests a new methodfor calculations of hydrogen atom in external fields.
Directory of Open Access Journals (Sweden)
Xiaoqing Wang
2016-01-01
Full Text Available Parallel analyses about the dynamic responses of a large-scale water conveyance tunnel under seismic excitation are presented in this paper. A full three-dimensional numerical model considering the water-tunnel-soil coupling is established and adopted to investigate the tunnel’s dynamic responses. The movement and sloshing of the internal water are simulated using the multi-material Arbitrary Lagrangian Eulerian (ALE method. Nonlinear fluid–structure interaction (FSI between tunnel and inner water is treated by using the penalty method. Nonlinear soil-structure interaction (SSI between soil and tunnel is dealt with by using the surface to surface contact algorithm. To overcome computing power limitations and to deal with such a large-scale calculation, a parallel algorithm based on the modified recursive coordinate bisection (MRCB considering the balance of SSI and FSI loads is proposed and used. The whole simulation is accomplished on Dawning 5000 A using the proposed MRCB based parallel algorithm optimized to run on supercomputers. The simulation model and the proposed approaches are validated by comparison with the added mass method. Dynamic responses of the tunnel are analyzed and the parallelism is discussed. Besides, factors affecting the dynamic responses are investigated. Better speedup and parallel efficiency show the scalability of the parallel method and the analysis results can be used to aid in the design of water conveyance tunnels.
A WENO-type slope-limiter for a family of piecewise polynomial methods
Engwirda, Darren
2016-01-01
A new, high-order slope-limiting procedure for the Piecewise Parabolic Method (PPM) and the Piecewise Quartic Method (PQM) is described. Following a Weighted Essentially Non-Oscillatory (WENO)-type paradigm, the proposed slope-limiter seeks to reconstruct smooth, non-oscillatory piecewise polynomial profiles as a non-linear combination of the natural and monotone-limited PPM and PQM interpolants. Compared to existing monotone slope-limiting techniques, this new strategy is designed to improve accuracy at smooth extrema, while controlling spurious oscillations in the neighbourhood of sharp features. Using the new slope-limited PPM and PQM interpolants, a high-order accurate Arbitrary-Lagrangian-Eulerian framework for advection-dominated flows is constructed, and its effectiveness is examined using a series of one- and two-dimensional benchmark cases. It is shown that the new WENO-type slope-limiting techniques offer a significant improvement in accuracy compared to existing strategies, allowing the PPM- and PQ...
Ren, Xiaodong; Xu, Kun; Shyy, Wei
2016-07-01
This paper presents a multi-dimensional high-order discontinuous Galerkin (DG) method in an arbitrary Lagrangian-Eulerian (ALE) formulation to simulate flows over variable domains with moving and deforming meshes. It is an extension of the gas-kinetic DG method proposed by the authors for static domains (X. Ren et al., 2015 [22]). A moving mesh gas kinetic DG method is proposed for both inviscid and viscous flow computations. A flux integration method across a translating and deforming cell interface has been constructed. Differently from the previous ALE-type gas kinetic method with piecewise constant mesh velocity at each cell interface within each time step, the mesh velocity variation inside a cell and the mesh moving and rotating at a cell interface have been accounted for in the finite element framework. As a result, the current scheme is applicable for any kind of mesh movement, such as translation, rotation, and deformation. The accuracy and robustness of the scheme have been improved significantly in the oscillating airfoil calculations. All computations are conducted in a physical domain rather than in a reference domain, and the basis functions move with the grid movement. Therefore, the numerical scheme can preserve the uniform flow automatically, and satisfy the geometric conservation law (GCL). The numerical accuracy can be maintained even for a largely moving and deforming mesh. Several test cases are presented to demonstrate the performance of the gas-kinetic DG-ALE method.
Energy Technology Data Exchange (ETDEWEB)
Hong Luo; Luqing Luo; Robert Nourgaliev; Vincent A. Mousseau
2010-01-01
A reconstruction-based discontinuous Galerkin (RDG) method is presented for the solution of the compressible Navier-Stokes equations on arbitrary grids. The RDG method, originally developed for the compressible Euler equations, is extended to discretize viscous and heat fluxes in the Navier-Stokes equations using a so-called inter-cell reconstruction, where a smooth solution is locally reconstructed using a least-squares method from the underlying discontinuous DG solution. Similar to the recovery-based DG (rDG) methods, this reconstructed DG method eliminates the introduction of ad hoc penalty or coupling terms commonly found in traditional DG methods. Unlike rDG methods, this RDG method does not need to judiciously choose a proper form of a recovered polynomial, thus is simple, flexible, and robust, and can be used on arbitrary grids. The developed RDG method is used to compute a variety of flow problems on arbitrary meshes to demonstrate its accuracy, efficiency, robustness, and versatility. The numerical results indicate that this RDG method is able to deliver the same accuracy as the well-known Bassi-Rebay II scheme, at a half of its computing costs for the discretization of the viscous fluxes in the Navier-Stokes equations, clearly demonstrating its superior performance over the existing DG methods for solving the compressible Navier-Stokes equations.
Piret, Cécile
2012-05-01
Much work has been done on reconstructing arbitrary surfaces using the radial basis function (RBF) method, but one can hardly find any work done on the use of RBFs to solve partial differential equations (PDEs) on arbitrary surfaces. In this paper, we investigate methods to solve PDEs on arbitrary stationary surfaces embedded in . R3 using the RBF method. We present three RBF-based methods that easily discretize surface differential operators. We take advantage of the meshfree character of RBFs, which give us a high accuracy and the flexibility to represent the most complex geometries in any dimension. Two out of the three methods, which we call the orthogonal gradients (OGr) methods are the result of our work and are hereby presented for the first time. © 2012 Elsevier Inc.
Energy Technology Data Exchange (ETDEWEB)
Carrington, David Bradley [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Monayem, A. K. M. [Univ. of New Mexico, Albuquerque, NM (United States); Mazumder, H. [Univ. of New Mexico, Albuquerque, NM (United States); Heinrich, Juan C. [Univ. of New Mexico, Albuquerque, NM (United States)
2015-03-05
A three-dimensional finite element method for the numerical simulations of fluid flow in domains containing moving rigid objects or boundaries is developed. The method falls into the general category of Arbitrary Lagrangian Eulerian methods; it is based on a fixed mesh that is locally adapted in the immediate vicinity of the moving interfaces and reverts to its original shape once the moving interfaces go past the elements. The moving interfaces are defined by separate sets of marker points so that the global mesh is independent of interface movement and the possibility of mesh entanglement is eliminated. The results is a fully robust formulation capable of calculating on domains of complex geometry with moving boundaries or devises that can also have a complex geometry without danger of the mesh becoming unsuitable due to its continuous deformation thus eliminating the need for repeated re-meshing and interpolation. Moreover, the boundary conditions on the interfaces are imposed exactly. This work is intended to support the internal combustion engines simulator KIVA developed at Los Alamos National Laboratories. The model's capabilities are illustrated through application to incompressible flows in different geometrical settings that show the robustness and flexibility of the technique to perform simulations involving moving boundaries in a three-dimensional domain.
New finite volume methods for approximating partial differential equations on arbitrary meshes
International Nuclear Information System (INIS)
This dissertation presents some new methods of finite volume type for approximating partial differential equations on arbitrary meshes. The main idea lies in solving twice the problem to be dealt with. One addresses the elliptic equations with variable (anisotropic, antisymmetric, discontinuous) coefficients, the parabolic linear or non linear equations (heat equation, radiative diffusion, magnetic diffusion with Hall effect), the wave type equations (Maxwell, acoustics), the elasticity and Stokes'equations. Numerous numerical experiments show the good behaviour of this type of method. (author)
A new method for calculating the scattered field by an arbitrary cross-sectional conducting cylinder
Ragheb, Hassan A.
2011-04-01
Scattering of a plane electromagnetic wave by an arbitrary cross-sectional perfectly conducting cylinder must be performed numerically. This article aims to present a new approach for addressing this problem, which is based on simulating the arbitrary cross-sectional perfectly conducting cylinder by perfectly conducting strips of narrow width. The problem is then turned out to calculate the scattered electromagnetic field from N conducting strips. The technique of solving such a problem uses an asymptotic method. This method is based on an approximate technique introduced by Karp and Russek (Karp, S.N., and Russek, A. (1956), 'Diffraction by a Wide Slit', Journal of Applied Physics, 27, 886-894.) for solving scattering by wide slit. The method is applied here for calculating the scattered field in the far zone for E-polarised incident waves (transverse magnetic (TM) with respect to z-axis) on a perfectly conducting cylinder with arbitrary cross-section. Numerical examples are introduced first for comparison to show the accuracy of the method. Other examples for well-known scattering by conducting cylinders are then introduced followed by new examples which can only be solved by numerical methods.
A Finite Field Method for Calculating Molecular Polarizability Tensors for Arbitrary Multipole Rank
Elking, Dennis M.; Perera, Lalith; Duke, Robert; Darden, Thomas; Pedersen, Lee G.
2011-01-01
A finite field method for calculating spherical tensor molecular polarizability tensors αlm;l′m′ = ∂Δlm/∂ϕl′m′* by numerical derivatives of induced molecular multipole Δlm with respect to gradients of electrostatic potential ϕl′m′* is described for arbitrary multipole ranks l and l′. Inter-conversion formulae for transforming multipole moments and polarizability tensors between spherical and traceless Cartesian tensor conventions are derived. As an example, molecular polarizability tensors up...
Energy Technology Data Exchange (ETDEWEB)
Hong Luo; Hanping Xiao; Robert Nourgaliev; Chunpei Cai
2011-06-01
A comparative study of different reconstruction schemes for a reconstruction-based discontinuous Galerkin, termed RDG(P1P2) method is performed for compressible flow problems on arbitrary grids. The RDG method is designed to enhance the accuracy of the discontinuous Galerkin method by increasing the order of the underlying polynomial solution via a reconstruction scheme commonly used in the finite volume method. Both Green-Gauss and least-squares reconstruction methods and a least-squares recovery method are implemented to obtain a quadratic polynomial representation of the underlying discontinuous Galerkin linear polynomial solution on each cell. These three reconstruction/recovery methods are compared for a variety of compressible flow problems on arbitrary meshes to access their accuracy and robustness. The numerical results demonstrate that all three reconstruction methods can significantly improve the accuracy of the underlying second-order DG method, although the least-squares reconstruction method provides the best performance in terms of both accuracy and robustness.
Chen, Ying; Yang, Xiangbo
In this paper, we present the direct-substitution (DS) method to study the second-harmonic generation (SHG) in arbitrary one-dimensional optical superlattices (OS). Applying this method to Fibonacci and generalized Fibonacci systems, we obtain the relative intensity of SHG and compare them with previous works. We confirmed the validity of the proposed DS method by comparing our results of SHG in quasiperiodic Fibonacci OS with previous works using analytical Fourier transform method. Furthermore, the three-dimension SHG spectra obtained by DS method present the properties of SHG in Fibonacci OS more distinctly. What's more important, the DS method demands very few limits and can be used to compute directly and conveniently the intensity of SHG in arbitrary OS where the quasi-phase-matching (QPM) can be achieved. It shows that the DS method is powerful for the calculation of electric field and intensity of SHG and can help experimentalists conveniently to estimate the distributions of SHG in any designed polarized systems.
Institute of Scientific and Technical Information of China (English)
黄弘; 胡啸峰; 申世飞; 原智宏; 冈林一木; 大场良二
2011-01-01
A hybrid atmospheric dispersion method coupled with Lagrangian particle model and Eulerian model is proposed,which can be used for numerical simulation in areas around urban buildings.This method merges the advantages of Lagrangian model and Eulerian model together,and gives a high accuracy of prediction.The developed hybrid model is applied to the numerical simulation of gas diffusion around an isolated building.The mean wind velocity,TKE（Turbulent Kinetic Energy） and mean concentration have been discussed and compared with the wind tunnel data.The simulation results show that the hybrid model can give a high accuracy both in the regions close to the source and distant from the source.Finally,we use the COST-732 model to evaluate the prediction results of Eulerian,Lagrangian and the proposed hybrid model,and it is shown that the hybrid model can give the best simulation results.%该文旨在建立一个适用于城市建筑物周边的基于Lagrangian模型与Eulerian模型耦合的气体扩散数值模型,同时具有Lagrangian模型与Eulerian模型各自的优点,提高预测精度。该文利用耦合模型对单个建筑物周边的气体扩散过程进行数值模拟,并将平均风速、湍流动能和平均浓度几个参量的结果与风洞实验数据进行对比分析。结果表明,耦合模型对于建筑物周边靠近扩散源和远离扩散源的区域均能给出较高精度的预测结果。最后,利用COST-732模型评价方法对Lagrangian模型、Eulerian模型和耦合扩散模型实施了评价,其中耦合模型的评价结果最好。
Arbitrary Difference Precise Integration Method for Solving the Seismic Wave Equation
Institute of Scientific and Technical Information of China (English)
Jia Xiaofeng; Wang Runqiu; Hu Tianyue
2004-01-01
Wave equation migration is often applied to solve seismic imaging problems. Usually, the finite difference method is used to obtain the numerical solution of the wave equation. In this paper,the arbitrary difference precise integration (ADPI) method is discussed and applied in seismic migration. The ADPI method has its own distinctive idea. When dispersing coordinates in the space domain, it employs a relatively unrestrained form instead of the one used by the conventional finite difference method. Moreover, in the time domain it adopts the sub-domain precise integration method. As a result, it not only takes the merits of high precision and narrow bandwidth, but also can process various boundary conditions and describe the feature of an inhomogeneous medium better. Numerical results show the benefit of the presented algorithm using the ADPI method.
Arbitrary Order Mixed Mimetic Finite Differences Method with Nodal Degrees of Freedom
Energy Technology Data Exchange (ETDEWEB)
Iaroshenko, Oleksandr [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gyrya, Vitaliy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Manzini, Gianmarco [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-09-01
In this work we consider a modification to an arbitrary order mixed mimetic finite difference method (MFD) for a diffusion equation on general polygonal meshes [1]. The modification is based on moving some degrees of freedom (DoF) for a flux variable from edges to vertices. We showed that for a non-degenerate element this transformation is locally equivalent, i.e. there is a one-to-one map between the new and the old DoF. Globally, on the other hand, this transformation leads to a reduction of the total number of degrees of freedom (by up to 40%) and additional continuity of the discrete flux.
Level Set Projection Method for Incompressible Navier-Stokes on Arbitrary Boundaries
Williams-Rioux, Bertrand
2012-01-12
Second order level set projection method for incompressible Navier-Stokes equations is proposed to solve flow around arbitrary geometries. We used rectilinear grid with collocated cell centered velocity and pressure. An explicit Godunov procedure is used to address the nonlinear advection terms, and an implicit Crank-Nicholson method to update viscous effects. An approximate pressure projection is implemented at the end of the time stepping using multigrid as a conventional fast iterative method. The level set method developed by Osher and Sethian [17] is implemented to address real momentum and pressure boundary conditions by the advection of a distance function, as proposed by Aslam [3]. Numerical results for the Strouhal number and drag coefficients validated the model with good accuracy for flow over a cylinder in the parallel shedding regime (47 < Re < 180). Simulations for an array of cylinders and an oscillating cylinder were performed, with the latter demonstrating our methods ability to handle dynamic boundary conditions.
Lagrangian-Eulerian simulation of slugging fluidized bed
Institute of Scientific and Technical Information of China (English)
Guorong Wu; Jie Ouyang; Binxin Yang; Qiang Li; Fang Wang
2012-01-01
This work studies gas-solid slugging fluidized beds with Type-D particles,using two-dimensional simulations based on discrete element model (DEM).DEM performance is quantitatively validated by two commonly accepted correlations for determining slugging behavior.The voidage profiles simulated with bed height corresponding to Baeyens and Geldart (1974) correlation for onset of slugging demonstrate a transitional flow pattern from free bubbling to slugging.The present calculated values for the maximum slugging bed height are in good agreement with the correlation from Matsen et al.(1969).Simulations show that fluidized beds with Type-D particles can operate in the round-nosed slugging regime and also shows that wall slugs and square-nosed slugs tend to be formed with increase in superficial gas velocity and in bed height,respectively.
On Hamiltonian Magnetohydrodynamics: Lagrangian, Eulerian and Dynamically Accessible Stability
Andreussi, Tommaso; Morrison, Philip J.; Pegoraro, Francesco
2013-10-01
Stability conditions of magnetized plasma flows are obtained by exploiting the Hamiltonian structure of the magnetohydrodynamics (MHD) equations by using three kinds of energy principles. First, the Lagrangian variable energy principle is described and sufficient stability conditions are presented. Next, plasma flows are described in terms of Eulerian variables and the noncanonical Hamiltonian formulation of MHD is exploited. For symmetric equilibria, the energy-Casimir principle is expanded to second order and sufficient conditions for stability to symmetric perturbation are obtained. Then, dynamically accessible variations, i.e. variations that explicitly preserve invariants of the system, are introduced and the respective energy principle is considered. General criteria for stability are obtained, along with comparisons between the three different approaches. En route to our results we describe a time-dependent relabeling transformation, which to our knowledge has not heretofore been given, that will be needed in the Lagrangian variable framework in connection with the approach considered in E. A. Frieman, M. Rotenberg, Rev. Mod. Phys. 32, 898 (1960).
Lagrangian, Eulerian, and Dynamically Accessible Stability of MHD flows
Andreussi, Tommaso; Morrison, Philip; Pegoraro, Francesco
2012-10-01
Stability conditions of magnetized plasma flows are obtained by exploiting the Hamiltonian structure of the magnetohydrodynamics (MHD) equations and, in particular, by using three kinds of energy principles. First, the Lagrangian energy principle of Ref. [1] is introduced and sufficient stability conditions are presented. Next, plasma flows are described in terms of Eulerian variables and the noncanonical Hamiltonian formulation of MHD [2] is exploited. For symmetric equilibria, the energy-Casimir principle of Ref. [3] is expanded to second order and sufficient conditions for stability to symmetric perturbation are obtained. Then, dynamically accessible variations, i.e. variations that explicitly preserve the invariants of the system, are introduced and the respective energy principle is considered. As in Ref. [4], general criteria for stability are obtained. A comparison between the three different approaches is finally presented. [4pt] [1] E.A. Frieman and M. Rotenberg, Rev. Mod. Phys., 32 898 (1960).[0pt] [2] P.J. Morrison, J.M. Greene, Phys. Rev. Lett., 45 790 (1980).[0pt] [3] T. Andreussi, P.J. Morrison, F. Pegoraro, Phys. Plasmas, 19 052102 (2012).[0pt] [4] E. Hameiri, Phys. Plasmas, 10 2643 (2003).
Maskew, B.
1976-01-01
A discrete singularity method has been developed for calculating the potential flow around two-dimensional airfoils. The objective was to calculate velocities at any arbitrary point in the flow field, including points that approach the airfoil surface. That objective was achieved and is demonstrated here on a Joukowski airfoil. The method used combined vortices and sources ''submerged'' a small distance below the airfoil surface and incorporated a near-field subvortex technique developed earlier. When a velocity calculation point approached the airfoil surface, the number of discrete singularities effectively increased (but only locally) to keep the point just outside the error region of the submerged singularity discretization. The method could be extended to three dimensions, and should improve nonlinear methods, which calculate interference effects between multiple wings, and which include the effects of force-free trailing vortex sheets. The capability demonstrated here would extend the scope of such calculations to allow the close approach of wings and vortex sheets (or vortices).
An arbitrary boundary triangle mesh generation method for multi-modality imaging
Zhang, Xuanxuan; Deng, Yong; Gong, Hui; Meng, Yuanzheng; Yang, Xiaoquan; Luo, Qingming
2012-03-01
Low-resolution and ill-posedness are the major challenges in diffuse optical tomography(DOT)/fluorescence molecular tomography(FMT). Recently, the multi-modality imaging technology that combines micro-computed tomography (micro-CT) with DOT/FMT is developed to improve resolution and ill-posedness. To take advantage of the fine priori anatomical maps obtained from micro-CT, we present an arbitrary boundary triangle mesh generation method for FMT/DOT/micro-CT multi-modality imaging. A planar straight line graph (PSLG) based on the image of micro-CT is obtained by an adaptive boundary sampling algorithm. The subregions of mesh are accurately matched with anatomical structures by a two-step solution, firstly, the triangles and nodes during mesh refinement are labeled respectively, and then a revising algorithm is used to modifying meshes of each subregion. The triangle meshes based on a regular model and a micro-CT image are generated respectively. The results show that the subregions of triangle meshes can match with anatomical structures accurately and triangle meshes have good quality. This provides an arbitrary boundaries triangle mesh generation method with the ability to incorporate the fine priori anatomical information into DOT/FMT reconstructions.
Towards Simulation of Clogging Effects in Wastewater Pumps
DEFF Research Database (Denmark)
Jensen, Anna Lyhne; Sørensen, Henrik; Rosendahl, Lasse Aistrup;
2015-01-01
are identified and compared. These methods are the Arbitrary Lagrangian-Eulerian (ALE) method, Immersed Boundary (IB) method, Smoothed Particle Hydrodynamics (SPH) coupled with the Finite Element method (FEM), and Computational Fluid Dynamics (CFD) coupled with the Discrete Element method (DEM). Each method has...
Universal method for the synthesis of arbitrary polarization states radiated by a nanoantenna
Rodriguez-Fortuno, Francisco J; Griol, Amadeu; Bellieres, Laurent; Marti, Javier; Martinez, Alejandro
2015-01-01
Optical nanoantennas efficiently convert confined optical energy into free-space radiation. The polarization of the emitted radiation depends mainly on nanoantenna shape, so it becomes extremely difficult to manipulate it unless the nanostructure is physically altered. Here we demonstrate a simple way to synthetize the polarization of the radiation emitted by a single nanoantenna so that every point on the Poincar\\'e sphere becomes attainable. The nanoantenna consists of a single scatterer created on a dielectric waveguide and fed from its both sides so that the polarization of the emitted optical radiation is controlled by the amplitude and phase of the feeding signals. Our nanoantenna is created on a silicon chip using standard top-down nanofabrication tools, but the method is universal and can be applied to other materials, wavelengths and technologies. This work will open the way towards the synthesis and control of arbitrary polarization states in nano-optics.
Design method for electromagnetic cloak with arbitrary shapes based on Laplace's equation.
Hu, Jin; Zhou, Xiaoming; Hu, Gengkai
2009-02-01
In transformation optics, the space transformation is viewed as the deformation of a material. The permittivity and permeability tensors in the transformed space are found to correlate with the deformation field of the material. By solving the Laplace's equation, which describes how the material will deform during a transformation, we can design electromagnetic cloaks with arbitrary shapes if the boundary conditions of the cloak are considered. As examples, the material parameters of the spherical and elliptical cylindrical cloaks are derived based on the analytical solutions of the Laplace's equation. For cloaks with irregular shapes, the material parameters of the transformation medium are determined numerically by solving the Laplace's equation. Full-wave simulations based on the Maxwell's equations validate the designed cloaks. The proposed method can be easily extended to design other transformation materials for electromagnetic and acoustic wave phenomena. PMID:19188959
Papamichael, K.; Beltran, L.
1993-04-01
A new method to simulate the daylight performance of fenestration systems and spaces is presented. This new method, named IDC (Integration of Directional Coefficients), allows the simulation of the daylight performance of fenestration systems and spaces of arbitrary complexity, under any sun, sky, and ground conditions. The IDC method is based on the combination of scale model photometry and computer-based simulation. Physical scale models are used to experimentally determine a comprehensive set of 'directional illuminance coefficients' at reference points of interest, which are then used in analytical, computer-based routines, to determine daylight factors or actual daylight illuminance values under any sun, sky, and ground conditions. The main advantage of the IDC method is its applicability to any optically complex environment. Moreover, the computer-based analytical routines are fast enough to allow for hourly simulation of the daylight performance over the course of an entire year. However, the method requires appropriate experimental facilities for the determination of the Directional Coefficients. The IDC method has been implemented and used successfully in inter-validation procedures with various daylight simulation computer programs. Currently, it is used to simulate the daylight performance of fenestration systems that incorporate optically complex components, such as Venetian blinds, optically treated light shelves and light pipes.
Ayzatsky, M I
2016-01-01
We present the short description of the methods for calculation of the coupling coefficients in the Coupling Cavity Model of arbitrary chain of resonators. In the first part the procedure that is based on the Mode Matching Method is given. Then we present the new method that used only one eigen vector.
Vibration analysis of pipelines with arbitrary branches by absorbing transfer matrix method
Liu, Gongmin; Li, Shuaijun; Li, Yanhua; Chen, Hao
2013-11-01
Branched pipes of arbitrary shapes are prevalent in pipe systems. Considering fluid-structure interaction (FSI), an absorbing transfer matrix method in frequency domain for fluid-filled pipelines with any branched pipes is proposed in this paper. A dominant chain of pipeline would be selected, and the point transfer matrix of each junction on the dominant chain would be determined. Here, the point transfer matrix, representing the influence of branched pipes at the junction on the dominant pipeline, was "absorbed" by the dominant chain. Based on these, with transfer matrixes of other elements, the fluid and structure dynamics problem could be solved following the chain transfer matrix method process. Several numerical examples with different constraints are presented to illustrate the application of the proposed method. Moreover, the experiment of cross-shaped pipes with various boundary conditions was carried out. And results from the present approach were validated by measured and numerical data. Then, the forced vibrations of branched pipes were analyzed by considering the effects of various parameters, which shows the fluid pressure and vibrations can be optimized by changing the branch angles and positions. Through these examples, it is shown that the proposed method is efficient and can be used to calculate branched pipes of any shape.
A finite field method for calculating molecular polarizability tensors for arbitrary multipole rank.
Elking, Dennis M; Perera, Lalith; Duke, Robert; Darden, Thomas; Pedersen, Lee G
2011-11-30
A finite field method for calculating spherical tensor molecular polarizability tensors α(lm;l'm') = ∂Δ(lm)/∂ϕ(l'm')* by numerical derivatives of induced molecular multipole Δ(lm) with respect to gradients of electrostatic potential ϕ(l'm')* is described for arbitrary multipole ranks l and l'. Interconversion formulae for transforming multipole moments and polarizability tensors between spherical and traceless Cartesian tensor conventions are derived. As an example, molecular polarizability tensors up to the hexadecapole-hexadecapole level are calculated for water using the following ab initio methods: Hartree-Fock (HF), Becke three-parameter Lee-Yang-Parr exchange-correlation functional (B3LYP), Møller-Plesset perturbation theory up to second order (MP2), and Coupled Cluster theory with single and double excitations (CCSD). In addition, intermolecular electrostatic and polarization energies calculated by molecular multipoles and polarizability tensors are compared with ab initio reference values calculated by the Reduced Variation Space method for several randomly oriented small molecule dimers separated by a large distance. It is discussed how higher order molecular polarizability tensors can be used as a tool for testing and developing new polarization models for future force fields. PMID:21915883
An Arbitrary Curvilinear Coordinate Method for Particle-In-Cell Modeling
Fichtl, C A; Cartwright, K L
2012-01-01
A new approach to the kinetic simulation of plasmas in complex geometries, based on the Particle-in- Cell (PIC) simulation method, is explored. In the two dimensional (2d) electrostatic version of our method, called the Arbitrary Curvilinear Coordinate PIC (ACC-PIC) method, all essential PIC operations are carried out in 2d on a uniform grid on the unit square logical domain, and mapped to a nonuniform boundary-fitted grid on the physical domain. As the resulting logical grid equations of motion are not separable, we have developed an extension of the semi-implicit Modified Leapfrog (ML) integration technique to preserve the symplectic nature of the logical grid particle mover. A generalized, curvilinear coordinate formulation of Poisson's equations to solve for the electrostatic fields on the uniform logical grid is also developed. By our formulation, we compute the plasma charge density on the logical grid based on the particles' positions on the logical domain. That is, the plasma particles are weighted to...
Directory of Open Access Journals (Sweden)
SZOPOS, E.
2012-05-01
Full Text Available This paper presents an iterative method for designing FIR filters that implement arbitrary magnitude characteristics, defined by the user through a set of frequency-magnitude points (frequency samples. The proposed method is based on the non-uniform frequency sampling algorithm. For each iteration a new set of frequency samples is generated, by processing the set used in the previous run; this implies changing the samples location around the previous frequency values and adjusting their magnitude through interpolation. If necessary, additional samples can be introduced, as well. After each iteration the magnitude characteristic of the resulting filter is determined by using the non-uniform DFT and compared with the required one; if the errors are larger than the acceptable levels (set by the user a new iteration is run; the length of the resulting filter and the values of its coefficients are also taken into consideration when deciding a re-run. To demonstrate the efficiency of the proposed method a tool for designing FIR filters that match human audiograms was implemented in LabVIEW. It was shown that the resulting filters have smaller coefficients than the standard one, and can also have lower order, while the errors remain relatively small.
Energy Technology Data Exchange (ETDEWEB)
Rancourt, D.G.; Ping, J.Y. (Ottawa-Carleton Inst. for Physics, Ottawa Univ., Ontario (Canada))
1991-05-01
We introduce a powerful approach for obtaining arbitrary-shape static hyperfine parameter distributions from thickness corrected Moessbauer spectra. The distributions are taken to be sums of Gaussian components and the corresponding spectra are shown analytically to be sums of Voigt lines. Three cases are worked out in detail for distributions of: (1) center shifts, (2) quadrupole splittings with linear coupling to center shifts, and (3) hyperfine fields with linear couplings to center shifts and quadrupole splittings. The domain of validity of our method is described, with particular attention given to recognizing the presence of dynamic effects. An application of hyperfine field distributions to the spectra of Fe-Ni alloys is given. In all cases, convergence is rapid and unambiguous with only two or three Gaussian components being needed for ideal fits. Adding more components does not destabilize the solution but only results in the same distribution and the same value sof all the parameters being obtained. Problems occurring with other methods are eliminated by design - given the intrinsic suitability of an expansion in terms of Gaussians. (orig.).
Directory of Open Access Journals (Sweden)
Tsugio Fukuchi
2014-06-01
Full Text Available The finite difference method (FDM based on Cartesian coordinate systems can be applied to numerical analyses over any complex domain. A complex domain is usually taken to mean that the geometry of an immersed body in a fluid is complex; here, it means simply an analytical domain of arbitrary configuration. In such an approach, we do not need to treat the outer and inner boundaries differently in numerical calculations; both are treated in the same way. Using a method that adopts algebraic polynomial interpolations in the calculation around near-wall elements, all the calculations over irregular domains reduce to those over regular domains. Discretization of the space differential in the FDM is usually derived using the Taylor series expansion; however, if we use the polynomial interpolation systematically, exceptional advantages are gained in deriving high-order differences. In using the polynomial interpolations, we can numerically solve the Poisson equation freely over any complex domain. Only a particular type of partial differential equation, Poisson's equations, is treated; however, the arguments put forward have wider generality in numerical calculations using the FDM.
Li, Lifeng
2015-10-01
An efficient modal method for numerically modeling slanted lamellar gratings of isotropic dielectric or metallic media in conical mounting is presented. No restrictions are imposed on the slant angle and the length of the lamellae. The end surface of the lamellae can be arbitrary, subject to certain restrictions. An oblique coordinate system that is adapted to the slanted lamella sidewalls allows the most efficient way of representing and manipulating the electromagnetic fields. A translational coordinate system that is based on the oblique Cartesian coordinate system adapts to the end-surface profile of the lamellae, so that the latter can be handled simply and easily. Moreover, two matrix eigenvalue problems of size 2N × 2N, one for each fundamental polarization of the electromagnetic fields in the periodic lamellar structure, where N is the matrix truncation number, are derived to replace the 4N × 4N eigenvalue problem that has been used in the literature. The core idea leading to this success is the polarization decomposition of the electromagnetic fields inside the periodic lamellar region when the fields are expressed in the oblique translational coordinate system. PMID:26479927
Khoudeir, A.; Montemayor, R.; Urrutia, Luis F.
2008-09-01
Using the parent Lagrangian method together with a dimensional reduction from D to (D-1) dimensions, we construct dual theories for massive spin two fields in arbitrary dimensions in terms of a mixed symmetry tensor TA[A1A2…AD-2]. Our starting point is the well-studied massless parent action in dimension D. The resulting massive Stueckelberg-like parent actions in (D-1) dimensions inherit all the gauge symmetries of the original massless action and can be gauge fixed in two alternative ways, yielding the possibility of having a parent action with either a symmetric or a nonsymmetric Fierz-Pauli field eAB. Even though the dual sector in terms of the standard spin two field includes only the symmetrical part e{AB} in both cases, these two possibilities yield different results in terms of the alternative dual field TA[A1A2…AD-2]. In particular, the nonsymmetric case reproduces the Freund-Curtright action as the dual to the massive spin two field action in four dimensions.
Second order multidimensional sign-preserving remapping for ALE methods
Energy Technology Data Exchange (ETDEWEB)
Hill, Ryan N [Los Alamos National Laboratory; Szmelter, J. [LOUGHBOROUGH UNIV.
2010-12-15
A second-order conservative sign-preserving remapping scheme for Arbitrary Lagrangian-Eulerian (ALE) methods is developed utilising concepts of the Multidimensional Positive Definite Advection Transport Algorithm (MPDATA). The algorithm is inherently multidimensional, and so does not introduce splitting errors. The remapping is implemented in a two-dimensional, finite element ALE solver employing staggered quadrilateral meshes. The MPDATA remapping uses a finite volume discretization developed for volume coordinates. It is applied for the remapping of density and internal energy arranged as cell centered, and velocity as nodal, dependent variables. In the paper, the advection of scalar fields is examined first for test cases with prescribed mesh movement. A direct comparison of MPDATA with the performance of the van Leer MUSCL scheme indicates advantages of a multidimensional approach. Furthermore, distinctly different performance between basic MPDATA and the infinite gauge option is illustrated using benchmarks involving transport of a sign changing velocity field. Further development extends the application of MPDATA remapping to the full ALE solver with a staggered mesh arrangement for density, internal energy and momentum using volume coordinates. At present, two options of the algorithm - basic and infinite gauge - are implemented. To ensure a meaningful assessment, an identical Lagrangian solver and computational mesh update routines are used with either MPDATA or van Leer MUSCL remapping. The evaluation places particular focus on the abilities of both schemes to accurately model multidimensional problems. Theoretical considerations are supported with numerical examples. In addition to the prescribed mesh movement cases for advection of scalars, the demonstrations include two-dimensional Eulerian and ALE flow simulations on quadrilateral meshes with both fixed and variable timestep control. The key comparisons include the standard test cases of Sod and Noh
Free surface modeling of contacting solid metal flows employing the ALE formulation
Stelt, van der A.A.; Bor, T.C.; Geijselaers, H.J.M.; Akkerman, R.; Huetink, J.; Merklein, M.; Hagenah, H.
2012-01-01
In this paper, a numerical problem with contacting solid metal flows is presented and solved with an arbitrary Lagrangian-Eulerian (ALE) finite element method. The problem consists of two domains which mechanically interact with each other. For this simulation a new free surface boundary condition i
Energy Technology Data Exchange (ETDEWEB)
Manzini, Gianmarco [Los Alamos National Laboratory
2012-07-13
We develop and analyze a new family of virtual element methods on unstructured polygonal meshes for the diffusion problem in primal form, that use arbitrarily regular discrete spaces V{sub h} {contained_in} C{sup {alpha}} {element_of} N. The degrees of freedom are (a) solution and derivative values of various degree at suitable nodes and (b) solution moments inside polygons. The convergence of the method is proven theoretically and an optimal error estimate is derived. The connection with the Mimetic Finite Difference method is also discussed. Numerical experiments confirm the convergence rate that is expected from the theory.
Simulation of free surfaces in 3-D with the arbitrary Lagrange-Euler method
DEFF Research Database (Denmark)
Szabo, Peter; Hassager, Ole
1995-01-01
The arbitrary Lagrange-Euler (ALE) kinematic description has been implemented in a 3-D transient finite element program so as to simulate multiple fluid flows with Surfaces and interfaces of general shapes. The description of fluid interfaces includes continuity of velocity and a discontinuous...
A Nonconforming Arbitrary Quadrilateral Finite Element Method for Approximating Maxwell's Equations
Institute of Scientific and Technical Information of China (English)
Dongyang Shi; Lifang Pei; Shaochun Chen
2007-01-01
The main aim of this paper is to provide convergence analysis of Quasi-Wilson nonconforming finite element to Maxwell's equations under arbitrary quadrilateral meshes. The error estimates are derived, which are the same as those for conforming elements under conventional regular meshes.
Farhat, Charbel; Lakshminarayan, Vinod K.
2014-04-01
Embedded Boundary Methods (EBMs) for Computational Fluid Dynamics (CFD) are usually constructed in the Eulerian setting. They are particularly attractive for complex Fluid-Structure Interaction (FSI) problems characterized by large structural motions and deformations. They are also critical for flow problems with topological changes and FSI problems with cracking. For all of these problems, the alternative Arbitrary Lagrangian-Eulerian (ALE) methods are often unfeasible because of the issue of mesh crossovers. However for viscous flows, Eulerian EBMs for CFD do not track the boundary layers around dynamic rigid or flexible bodies. Consequently, the application of these methods to viscous FSI problems requires either a high mesh resolution in a large part of the computational fluid domain, or adaptive mesh refinement. Unfortunately, the first option is computationally inefficient, and the second one is labor intensive. For these reasons, an alternative approach is proposed in this paper for maintaining all moving boundary layers resolved during the simulation of a turbulent FSI problem using an EBM for CFD. In this approach, which is simple and computationally reasonable, the underlying non-body-fitted mesh is rigidly translated and/or rotated in order to track the rigid component of the motion of the dynamic obstacle. Then, the flow computations away from the embedded surface are performed using the ALE framework, and the wall boundary conditions are treated by the chosen Eulerian EBM for CFD. Hence, the solution of the boundary layer tracking problem proposed in this paper can be described as an ALE implementation of a given EBM for CFD. Its basic features are illustrated with the Large Eddy Simulation using a non-body-fitted mesh of a turbulent flow past an airfoil in heaving motion. Its strong potential for the solution of challenging FSI problems at reasonable computational costs is also demonstrated with the simulation of turbulent flows past a family of
Indian Academy of Sciences (India)
M. A. Sharaf; M. A. Banajh; A. A. Alshaary
2007-03-01
In this paper, an efficient iterative method of arbitrary integer order of convergence ≥ 2 has been established for solving the hyperbolic form of Kepler’s equation. The method is of a dynamic nature in the sense that, moving from one iterative scheme to the subsequent one, only additional instruction is needed. Most importantly, the method does not need any prior knowledge of the initial guess. A property which avoids the critical situations between divergent and very slow convergent solutions that may exist in other numerical methods which depend on initial guess. Computational Package for digital implementation of the method is given and is applied to many case studies.
Directory of Open Access Journals (Sweden)
Dong Tang
2016-01-01
Full Text Available An analytical procedure for free vibration analysis of circular cylindrical shells with arbitrary boundary conditions is developed with the employment of the method of reverberation-ray matrix. Based on the Flügge thin shell theory, the equations of motion are solved and exact solutions of the traveling wave form along the axial direction and the standing wave form along the circumferential direction are obtained. With such a unidirectional traveling wave form solution, the method of reverberation-ray matrix is introduced to derive a unified and compact form of equation for natural frequencies of circular cylindrical shells with arbitrary boundary conditions. The exact frequency parameters obtained in this paper are validated by comparing with those given by other researchers. The effects of the elastic restraints on the frequency parameters are examined in detail and some novel and useful conclusions are achieved.
A smooth dissipative particle dynamics method for domains with arbitrary-geometry solid boundaries
Gatsonis, Nikolaos A.; Potami, Raffaele; Yang, Jun
2014-01-01
A smooth dissipative particle dynamics method with dynamic virtual particle allocation (SDPD-DV) for modeling and simulation of mesoscopic fluids in wall-bounded domains is presented. The physical domain in SDPD-DV may contain external and internal solid boundaries of arbitrary geometries, periodic inlets and outlets, and the fluid region. The SDPD-DV method is realized with fluid particles, boundary particles, and dynamically allocated virtual particles. The internal or external solid boundaries of the domain can be of arbitrary geometry and are discretized with a surface grid. These boundaries are represented by boundary particles with assigned properties. The fluid domain is discretized with fluid particles of constant mass and variable volume. Conservative and dissipative force models due to virtual particles exerted on a fluid particle in the proximity of a solid boundary supplement the original SDPD formulation. The dynamic virtual particle allocation approach provides the density and the forces due to virtual particles. The integration of the SDPD equations is accomplished with a velocity-Verlet algorithm for the momentum and a Runge-Kutta for the entropy equation. The velocity integrator is supplemented by a bounce-forward algorithm in cases where the virtual particle force model is not able to prevent particle penetration. For the incompressible isothermal systems considered in this work, the pressure of a fluid particle is obtained by an artificial compressibility formulation for liquids and the ideal gas law for gases. The self-diffusion coefficient is obtained by an implementation of the generalized Einstein and the Green-Kubo relations. Field properties are obtained by sampling SDPD-DV outputs on a post-processing grid that allows harnessing the particle information on desired spatiotemporal scales. The SDPD-DV method is verified and validated with simulations in bounded and periodic domains that cover the hydrodynamic and mesoscopic regimes for
A smooth dissipative particle dynamics method for domains with arbitrary-geometry solid boundaries
Gatsonis, Nikolaos A.; Potami, Raffaele; Yang, Jun
2014-01-01
A smooth dissipative particle dynamics method with dynamic virtual particle allocation (SDPD-DV) for modeling and simulation of mesoscopic fluids in wall-bounded domains is presented. The physical domain in SDPD-DV may contain external and internal solid boundaries of arbitrary geometries, periodic inlets and outlets, and the fluid region. The SDPD-DV method is realized with fluid particles, boundary particles, and dynamically allocated virtual particles. The internal or external solid boundaries of the domain can be of arbitrary geometry and are discretized with a surface grid. These boundaries are represented by boundary particles with assigned properties. The fluid domain is discretized with fluid particles of constant mass and variable volume. Conservative and dissipative force models due to virtual particles exerted on a fluid particle in the proximity of a solid boundary supplement the original SDPD formulation. The dynamic virtual particle allocation approach provides the density and the forces due to virtual particles. The integration of the SDPD equations is accomplished with a velocity-Verlet algorithm for the momentum and a Runge-Kutta for the entropy equation. The velocity integrator is supplemented by a bounce-forward algorithm in cases where the virtual particle force model is not able to prevent particle penetration. For the incompressible isothermal systems considered in this work, the pressure of a fluid particle is obtained by an artificial compressibility formulation for liquids and the ideal gas law for gases. The self-diffusion coefficient is obtained by an implementation of the generalized Einstein and the Green-Kubo relations. Field properties are obtained by sampling SDPD-DV outputs on a post-processing grid that allows harnessing the particle information on desired spatiotemporal scales. The SDPD-DV method is verified and validated with simulations in bounded and periodic domains that cover the hydrodynamic and mesoscopic regimes for
Design Method for Electromagnetic Cloak with Arbitrary Shapes Based on Laplace's Equation
Hu, Jin; Zhou, Xiaoming; Hu, Gengkai
2008-01-01
In transformation optics, the space transformation is viewed as the deformation of a material. The permittivity and permeability tensors in the transformed space are found to correlate with the deformation field of the material. By solving the Laplace's equation, which describes how the material will deform during a transformation, we can design electromagnetic cloaks with arbitrary shapes if the boundary conditions of the cloak are considered. As examples, the material parameters of the sphe...
Energy Technology Data Exchange (ETDEWEB)
Preece, D.S.; Weatherby, J.R.; Attaway, S.W.; Swegle, J.W.; Matalucci, R.V.
1998-06-01
Coupled blast-structural computational simulations using supercomputer capabilities will significantly advance the understanding of how complex structures respond under dynamic loads caused by explosives and earthquakes, an understanding with application to the surety of both federal and nonfederal buildings. Simulation of the effects of explosives on structures is a challenge because the explosive response can best be simulated using Eulerian computational techniques and structural behavior is best modeled using Lagrangian methods. Due to the different methodologies of the two computational techniques and code architecture requirements, they are usually implemented in different computer programs. Explosive and structure modeling in two different codes make it difficult or next to impossible to do coupled explosive/structure interaction simulations. Sandia National Laboratories has developed two techniques for solving this problem. The first is called Smoothed Particle Hydrodynamics (SPH), a relatively new gridless method comparable to Eulerian, that is especially suited for treating liquids and gases such as those produced by an explosive. The SPH capability has been fully implemented into the transient dynamics finite element (Lagrangian) codes PRONTO-2D and -3D. A PRONTO-3D/SPH simulation of the effect of a blast on a protective-wall barrier is presented in this paper. The second technique employed at Sandia National Laboratories uses a relatively new code called ALEGRA which is an ALE (Arbitrary Lagrangian-Eulerian) wave code with specific emphasis on large deformation and shock propagation. ALEGRA is capable of solving many shock-wave physics problems but it is especially suited for modeling problems involving the interaction of decoupled explosives with structures.
Yang, Jinghao; Jia, Zhenyuan; Liu, Wei; Fan, Chaonan; Xu, Pengtao; Wang, Fuji; Liu, Yang
2016-10-01
Binocular vision systems play an important role in computer vision, and high-precision system calibration is a necessary and indispensable process. In this paper, an improved calibration method for binocular stereo vision measurement systems based on arbitrary translations and 3D-connection information is proposed. First, a new method for calibrating the intrinsic parameters of binocular vision system based on two translations with an arbitrary angle difference is presented, which reduces the effect of the deviation of the motion actuator on calibration accuracy. This method is simpler and more accurate than existing active-vision calibration methods and can provide a better initial value for the determination of extrinsic parameters. Second, a 3D-connection calibration and optimization method is developed that links the information of the calibration target in different positions, further improving the accuracy of the system calibration. Calibration experiments show that the calibration error can be reduced to 0.09%, outperforming traditional methods for the experiments of this study.
Hill, Peter; Dudson, Ben
2016-01-01
We present a technique for handling Dirichlet boundary conditions with the Flux Coordinate Independent (FCI) parallel derivative operator with arbitrary-shaped material geometry in general 3D magnetic fields. The FCI method constructs a finite difference scheme for $\
Institute of Scientific and Technical Information of China (English)
Zhou Qi
2012-01-01
To a large degree,language is arbitrary. But there are exceptions to prove that language is not always arbitrary. However,non-arbitrariness is itself inevitably arbitrary. In fact,arbitrariness and non-arbitrariness work together to complete a language. It seems that they contradict to each other, but they actually coexist as a whole in the same unity.
DEFF Research Database (Denmark)
Mejlbro, Leif
1997-01-01
An alternative formula for the solution of linear differential equations of order n is suggested. When applicable, the suggested method requires fewer and simpler computations than the well-known method using Wronskians....
International Nuclear Information System (INIS)
The ordinary least-square fitting with polynomial is used in both the dynamic phase of the watt balance method and the weighting phase of joule balance method but few researches have been conducted to evaluate the uncertainty of the fitting data in the electrical balance methods. In this paper, a matrix-calculation method for evaluating the uncertainty of the polynomial fitting data is derived and the properties of this method are studied by simulation. Based on this, another two derived methods are proposed. One is used to find the optimal fitting order for the watt or joule balance methods. Accuracy and effective factors of this method are experimented with simulations. The other is used to evaluate the uncertainty of the integral of the fitting data for joule balance, which is demonstrated with an experiment from the NIM-1 joule balance. (paper)
Directory of Open Access Journals (Sweden)
Ping Xu
2011-08-01
Full Text Available With the rapidly growing use of digital images in medical archival and communication, image compression technology, especially diagnosis lossless compression technology, plays a more and more important role for medical applications. In this thesis, a novel diagnosis loseless compression algorithm is presented for digital mammography. The mammogram is divided into breast region, pectoral muscle and background using the CAD technology. Then mutiple arbitrary shape ROIs coding framework is used to compress the mammogram in which the breast region and pectoral muscle are compressed losslessly and lossily respectively, and the background can be discarded or compressed lossily as user’s will. Experimental results show that the proposed method offer potential advantage in medical applications of digital mammography compression.
Institute of Scientific and Technical Information of China (English)
Nazaret Dermendjian; Vincent W. Lee; Jianwen Liang(梁建文)
2003-01-01
The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been studied. Nunerical computation of the wave displacement field is carried out on and near the canyon surfaces using weighted-residuals (moment method). The wave displacement fields are computed by the residual mcthod for the cases of elliptic, circular, rounded-rectangular and flat-elliptic canyons. The analysis demonstrates that thc resulting surface displacemcnt depends, as in similar previous analyses, on several factors including, but not limited, to the angle of thc wedge, thc geometry of thc vertex, the frcquencies of thc incident waves, the angles of incidence, and the material properties of the media. The analysis provides intriguing results that help to explain geophysical observations regarding the amplification of seismic energy as a function of site conditions.
Espino, Daniel M; Shepherd, Duncan E T; Hukins, David W L
2014-01-01
A transient multi-physics model of the mitral heart valve has been developed, which allows simultaneous calculation of fluid flow and structural deformation. A recently developed contact method has been applied to enable simulation of systole (the stage when blood pressure is elevated within the heart to pump blood to the body). The geometry was simplified to represent the mitral valve within the heart walls in two dimensions. Only the mitral valve undergoes deformation. A moving arbitrary Lagrange-Euler mesh is used to allow true fluid-structure interaction (FSI). The FSI model requires blood flow to induce valve closure by inducing strains in the region of 10-20%. Model predictions were found to be consistent with existing literature and will undergo further development.
TEMPELS, Heat Conduction for Arbitrary Geometry by Finite Element Method (FEM)
International Nuclear Information System (INIS)
1 - Description of problem or function: Simultaneous temperature and stress analysis in solids of a axisymmetric shape, subject to thermal and mechanical loading, used for fuel elements with fuel - cladding interaction. 2 - Method of solution: The finite-element body of revolution method in two dimensions is applied, using linear triangular finite elements with nodes at the vertices. The same procedure is used both for temperature and structural computation, and sets of linear equations are obtained to be solved by an iterative method
Jeromen, Andrej; Grabec, Igor; Govekar, Edvard
2015-01-01
A laser pulse transient method for measuring normal spectral emissivity is described. In this method, a laser pulse (l=1064 nm) irradiates the top surface of a flat specimen. A two-dimensional temperature response of the bottom surface is measured with a calibrated thermographic camera. By solving an axisymmetric boundary value heat conduction problem, the normal spectral emissivity at 1064 nm is determined by using an iterative nonlinear least-squares estimation procedure. The method can be ...
Numerical Method for laminar fully developed flow in arbitrary cross section of ducts
Directory of Open Access Journals (Sweden)
Beghdadi Lotfi
2015-06-01
Full Text Available The present paper deals with the approximation of the solutions of partial differential equations that describe the phenomena of heat transfer and fluid flow, using a method based on Stokes' theorem and applied an unstructured computational mesh. The thus developed method will be applied in a problem of heat transfer charactiristics of laminar fully developed flow. After developing a code for calculating quantitative tests are planned to determine the accuracy of the method by the comparison with analytical solution or other studies that are already done.
Multi-scale Godunov-type method for cell-centered discrete Lagrangian hydrodynamics
Maire, Pierre-Henri; Nkonga, Boniface
2009-02-01
This work presents a multi-dimensional cell-centered unstructured finite volume scheme for the solution of multimaterial compressible fluid flows written in the Lagrangian formalism. This formulation is considered in the Arbitrary-Lagrangian-Eulerian (ALE) framework with the constraint that the mesh velocity and the fluid velocity coincide. The link between the vertex velocity and the fluid motion is obtained by a formulation of the momentum conservation on a class of multi-scale encased volumes around mesh vertices. The vertex velocity is derived with a nodal Riemann solver constructed in such a way that the mesh motion and the face fluxes are compatible. Finally, the resulting scheme conserves both momentum and total energy and, it satisfies a semi-discrete entropy inequality. The numerical results obtained for some classical 2D and 3D hydrodynamic test cases show the robustness and the accuracy of the proposed algorithm.
International Nuclear Information System (INIS)
Neutron spectra have been measured by the foil-activation method in 13 different environments in and around the Sandia Pulsed Reactor, the White Sands Missile Range Fast Burst Reactor, and the Sandia Annular Core Research Reactor. The spectra were obtained by using the SANDII code in a manner that was not dependent on the initial trial. This altered technique is better suited for the determination of spectra in environments that are difficult to predict by calculation, and it tends to reveal features that may be biased out by the use of standard trial-dependent methods. For some of the configurations, studies have also been made of how well the solution is determined in each energy region. The experimental methods and the techniques used in the analyses are thoroughly explained. 34 refs., 51 figs., 40 tabs
Directory of Open Access Journals (Sweden)
Song Fu
2015-01-01
Full Text Available Although the uniform theory of diffraction (UTD could be theoretically applied to arbitrarilyshaped convex objects modeled by nonuniform rational B-splines (NURBS, one of the great challenges in calculation of the UTD surface diffracted fields is the difficulty in determining the geodesic paths along which the creeping waves propagate on arbitrarilyshaped NURBS surfaces. In differential geometry, geodesic paths satisfy geodesic differential equation (GDE. Hence, in this paper, a general and efficient adaptive variable step Euler method is introduced for solving the GDE on arbitrarilyshaped NURBS surfaces. In contrast with conventional Euler method, the proposed method employs a shape factor (SF ξ to efficiently enhance the accuracy of tracing and extends the application of UTD for practical engineering. The validity and usefulness of the algorithm can be verified by the numerical results.
A Unified Finite Element Method for Arbitrary Elastic and Acoustic Media
Karaoglu, H.; Bielak, J.
2011-12-01
This study reports on a mixed finite element formulation that overcomes certain limitations faced by low-order primal-based formulations. A primal-based formulation with displacement as the variable is a widely used method to solve wave-propagation problems. It has been observed, however, that its accuracy deteriorates badly with increasing contrast between the P- and S-wave velocities (a situation often referred to, inaccurately, as almost incompressible). The extreme case for this contrast is an ideal, compressible fluid medium with S-wave velocity equals to zero. This extreme case creates problems in the equations of compressible elasticity. By using a dual-based formulation, we develop a method that is robust within the entire range of an elastic solid with moderate contrast between the P- and S-wave velocities up to the limiting case of an acoustic medium for which the S-wave velocity is zero. By solving a constrained variational problem with the Lagrange-Multiplier Method, we developed the dual-based (mixed) formulation with pressure and displacement as the variables.This is similar to earlier mixed displacement-pressure formulations, except that we introduce the methodology as a global one applicable to different domains rather than being limited to certain extreme cases. The variational problem makes a wider range of interpolation functions permissible for pressure including discontinuous functions across element boundaries. We verify the method and illustrate the general principles with an application in Southern California of the 1994 Northridge earthquake. We also discuss the possible extension of the method to fluid-structure interaction problems with dry interface conditions.
FULLY NONLINEAR WAVE COMPUTATIONS FOR ARBITRARY FLOATING BODIES USING THE DELTA METHOD
Institute of Scientific and Technical Information of China (English)
Lee Tzung-hang
2003-01-01
Fully nonlinear water wave problems are solved using Eulerian-Lagrangian time stepping methods in conjunction with a desingularized approach to solve the mixed boundary value problem that arises at each time step. In the desingularized approach, the singularities generating the flow field are outside the fluid domain. This allows the singularity distribution to be replaced by isolated Rankine sources with the corresponding reduction in computational complexity and computer time. A moving boundary technique is applied to eliminate the reflection waves from limited computational boundaries. Examples of the use of the method in three-dimensions are given for the exciting forces acting on a modified wigley hull and Series 60 are presented. The numerical results show good agreements with those of experiments.
Integral method to study transition radiation from surfaces with arbitrary profile
Takakura, Y.; Haeberlé, Olivier
2000-01-01
International audience; Transition radiation is produced when an electron moving at constant speed crosses the boundary separating two media with different optical properties. We propose an alternative description of this phenomenon, based on an integral representation of the electromagnetic field and show that the approach gives known results for a flat surface. Compared to previously published methods, based either on the reciprocity theorem in electromagnetism or on a four-dimensional Four...
An Efficient ICT Method for Analysis of Co-planar Dipole Antenna Arrays of Arbitrary Lengths
Imoro, Adam Icarus; Aoki, Ippo; Inagaki, Naoki; Kikuma, Nobuyoshi; キクマ, ノブヨシ; 菊間, 信良
1998-01-01
A more judicious choice of trial functions to implement the Improved Circuit Theory (ICT) application to multi-element antennas is achieved. These new trial functions, based on Tai's modified variational implementation for single element antennas, leads to an ICT implementation applicable to much longer co-planar dipole arrays. The accuracy of the generalized impedance formulas is in good agreement with the method of moments. Moreover, all these generalized formulas including the radiation pa...
Arbitrary pattern fabrication with a LCD reticle-free exposure method
Morimoto, Tatsuo; Nakamura, Kazumitsu; Kubota, Hiroshi; Nakada, Akira; Akamichi, Takayuki; Inokuchi, Tsuneo; Kosaka, Kouji
2003-08-01
We describe a newly developed technique that uses optical projection lithography with a liquid crystal display (LCD) in place of a conventional reticle, in order to minimize turn-around-time and production cost. Circuit pattern data, generated by a computer aided design (CAD) system, is transferred directly to a control computer. The control computer converts the data into an equivalent dot matrix representation of the design for use on a LCD. The LCD is placed in a conventional optical stepper. One feature of this system is the simplicity of the data management scheme which permits the data to be handled by a computer file directly; without any of the manual assistance normally needed in conventional reticle fabrication. It is a very convenient method to reverse reticle tone by changing the LCD mode; easy compared to a conventional reticle manufacturing process. The minimum resolution of this proposed system is very similar to conventional systems that use optical reticles. We have demonstrated that this LCD Reticle-Free Exposure Method has the potential of replacing conventional reticles in optical stepper lithography. This method is applicable for manufacturing devices with relatively large fabrication rules and low production quantities, such as System-in-Package applications.
Use of the foil activation method with arbitrary trial functions to determine neutron energy spectra
International Nuclear Information System (INIS)
Neutron Spectra have been measured by the foil activation method in thirteen different environments in and around the Sandia Pulsed Reactor (SPR-III), the White Sands Missile Range FBR, and the Annular Core Research Reactor (ACRR). The unfolded spectra were obtained by using the SANDII code in a manner which was not dependent on the initial trial. This altered technique is, therefore, better suited for the determination of spectra in environments that are difficult to predict by calculation, and it tends to reveal features that may be biased out by the use of standard trial functions
Energy Technology Data Exchange (ETDEWEB)
MacAlpine, Sara; Deline, Chris
2015-09-15
It is often difficult to model the effects of partial shading conditions on PV array performance, as shade losses are nonlinear and depend heavily on a system's particular configuration. This work describes and implements a simple method for modeling shade loss: a database of shade impact results (loss percentages), generated using a validated, detailed simulation tool and encompassing a wide variety of shading scenarios. The database is intended to predict shading losses in crystalline silicon PV arrays and is accessed using basic inputs generally available in any PV simulation tool. Performance predictions using the database are within 1-2% of measured data for several partially shaded PV systems, and within 1% of those predicted by the full, detailed simulation tool on an annual basis. The shade loss database shows potential to considerably improve performance prediction for partially shaded PV systems.
High-Order Moving Overlapping Grid Methodology in a Spectral Element Method
Merrill, Brandon E.
A moving overlapping mesh methodology that achieves spectral accuracy in space and up to second-order accuracy in time is developed for solution of unsteady incompressible flow equations in three-dimensional domains. The targeted applications are in aerospace and mechanical engineering domains and involve problems in turbomachinery, rotary aircrafts, wind turbines and others. The methodology is built within the dual-session communication framework initially developed for stationary overlapping meshes. The methodology employs semi-implicit spectral element discretization of equations in each subdomain and explicit treatment of subdomain interfaces with spectrally-accurate spatial interpolation and high-order accurate temporal extrapolation, and requires few, if any, iterations, yet maintains the global accuracy and stability of the underlying flow solver. Mesh movement is enabled through the Arbitrary Lagrangian-Eulerian formulation of the governing equations, which allows for prescription of arbitrary velocity values at discrete mesh points. The stationary and moving overlapping mesh methodologies are thoroughly validated using two- and three-dimensional benchmark problems in laminar and turbulent flows. The spatial and temporal global convergence, for both methods, is documented and is in agreement with the nominal order of accuracy of the underlying solver. Stationary overlapping mesh methodology was validated to assess the influence of long integration times and inflow-outflow global boundary conditions on the performance. In a turbulent benchmark of fully-developed turbulent pipe flow, the turbulent statistics are validated against the available data. Moving overlapping mesh simulations are validated on the problems of two-dimensional oscillating cylinder and a three-dimensional rotating sphere. The aerodynamic forces acting on these moving rigid bodies are determined, and all results are compared with published data. Scaling tests, with both methodologies
Kovács, Balázs; Guerra, Christian Andreas Power
2014-01-01
A linear evolving surface partial differential equation is first discretized in space by an arbitrary Lagrangian Eulerian (ALE) evolving surface finite element method, and then in time either by a Runge-Kutta method, or by a backward difference formula. The ALE technique allows to maintain the mesh regularity during the time integration, which is not possible in the original evolving surface finite element method. Unconditional stability and optimal order convergence of the full discretizatio...
Desforges, Jean; Deschamps, Clément; Gauvin, Serge
2015-08-01
The determination of the complex refractive index of thin films usually requires the highest accuracy. In this paper, we report on a new and accurate method based on a spectral rectifying process of a single transmittance curve. The agreements with simulated and real experimental data show the helpfulness of the method. The case of materials having arbitrary absorption bands at midpoint in spectral range, such as pigments in guest-host polymers, is also encompassed by this method.
Stein, David B.; Guy, Robert D.; Thomases, Becca
2016-01-01
The Immersed Boundary method is a simple, efficient, and robust numerical scheme for solving PDE in general domains, yet it only achieves first-order spatial accuracy near embedded boundaries. In this paper, we introduce a new high-order numerical method which we call the Immersed Boundary Smooth Extension (IBSE) method. The IBSE method achieves high-order accuracy by smoothly extending the unknown solution of the PDE from a given smooth domain to a larger computational domain, enabling the use of simple Cartesian-grid discretizations (e.g. Fourier spectral methods). The method preserves much of the flexibility and robustness of the original IB method. In particular, it requires minimal geometric information to describe the boundary and relies only on convolution with regularized delta-functions to communicate information between the computational grid and the boundary. We present a fast algorithm for solving elliptic equations, which forms the basis for simple, high-order implicit-time methods for parabolic PDE and implicit-explicit methods for related nonlinear PDE. We apply the IBSE method to solve the Poisson, heat, Burgers', and Fitzhugh-Nagumo equations, and demonstrate fourth-order pointwise convergence for Dirichlet problems and third-order pointwise convergence for Neumann problems.
Oscillating layer thickness and vortices generated in oscillation of finite plate
Sin, V. K.; Wong, I. K.
2016-06-01
Moving mesh strategy is used in the model of flow induced by oscillating finite plate through software - COMSOL Multiphysics. Flow is assumed to be laminar and arbitrary Lagrangian-Eulerian method is used for moving mesh in the simulation. Oscillating layer thickness is found which is different from the analytical solution by 2 to 3 times depends on the oscillating frequency. Vortices are also observed near the oscillating finite plate because of the edge effect of the finite plate.
Energy Technology Data Exchange (ETDEWEB)
Dawes, Alan Sidney [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Malone, Christopher M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shashkov, Mikhail Jurievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-07-07
In this report a number of new verification test problems for multimaterial diffusion will be shown. Using them we will show that homogenization of multimaterial cells in either Arbitrary Lagrangian Eulerian (ALE) or Eulerian simulations can lead to errors in the energy flow at the interfaces. Results will be presented that show that significant improvements and predictive capability can be gained by using either a surrogate supermesh, such as Thin Mesh in FLAG, or the emerging method based on Static Condensation.
Energy Technology Data Exchange (ETDEWEB)
Zhang Sheng [Department of Mathematics, Bohai University, Jinzhou 121000 (China)], E-mail: zhshaeng@yahoo.com.cn
2008-03-10
In this Letter, the Exp-function method is used to seek generalized solitonary solutions of Riccati equation. Based on the Riccati equation and its generalized solitonary solutions, new exact solutions with three arbitrary functions of the (2+1)-dimensional Broer-Kaup-Kupershmidt equations are obtained. It is shown that the Exp-function method provides a straightforward and important mathematical tool for nonlinear evolution equations in mathematical physics.
安全气囊展开的三种数值模拟方法的对比%Comparison on three methods for simulating safety airbag deployment
Institute of Scientific and Technical Information of China (English)
车凯凯; 王美松
2013-01-01
在安全气囊实际开发中，利用仿真技术可降试验成本，缩短开发周期。针对控制体积法（CV）、任意Lagrange-Euler法（ALE）和粒子法（CPM）3种模拟方法，该文对比了各自的适用范围和优缺点，给出了各方法的理论模型以及有限元建模方法；结合某车型驾驶员侧折叠气囊，仿真对比了各方法的展开效果、温度、压力分布等主要参数。结果表明：CV法更适用于在位情况下的气囊仿真分析；而ALE法和CPM法可分析离位情况下气囊流场分布，且在气囊展开初期可考虑到气流效应对乘员的影响。该研究结果可为对气囊仿真方法的选择及气囊设计提供参考。%Numerical simulation technology is an important tool to reduce cost and time for safety airbag development. Three prevalent principal methods, i.e. the Control Volume Method (CV), the Arbitrary Lagrangian Eulerian Method (ALE), and the Corpuscular Method (CPM), were compared for the application and the characteristics of airbag. The deployment process, the temperatures, and the pressures were simulated using mathematic theories and ifnite element model for a developing vehicle with a folded driver side airbag. The simulation results of these methods show that the CV method is more suitable for airbag simulation under in position (IP) condition, while the ALE method and the CPM method are perfect for analyzing the lfow ifeld and its effects on passengers of airbag deployment under out of position (OOP) condition when taking into account lfow effect at the initial stages of airbag deployment. These results wil provide references for the selection simulation method and actual design for airbag deployment.
International Nuclear Information System (INIS)
A new 2D neutron transport code AutoMOC for arbitrary geometry has been developed. This code is based on the method of characteristics (MOCs) and the customization of AutoCAD. The MOC solves the neutron transport equation along characteristic lines. It is independent of the geometric shape of boundaries and regions. So theoretically, this method can be used to solve the neutron transport equation in highly complex geometries. However, it is important to describe the geometry and calculate intersection points of each characteristic line with every boundary and region in advance. In complex geometries, due to the complications of treating the arbitrary domain, the selection of geometric shapes and efficiency of ray tracing are generally limited. The geometry treatment through the customization of AutoCAD, a widely used computer-aided design software package, is given in this paper. Thanks to the powerful capability of AutoCAD, the description of arbitrary geometry becomes quite convenient. Moreover, with the language Visual Basic for Applications (VBAs), AutoCAD can be customized to carry out the ray tracing procedure with a high flexibility in geometry. The numerical results show that AutoMOC can solve 2D neutron transport problems in a complex geometry accurately and effectively
International Nuclear Information System (INIS)
This paper describes the ALICE-II analysis of and comparison with complex vessel experiments. Tests SM-2 through SM-5 were performed by SRI International in 1978 in studying the structural response of 1/20 scale models of the Clinch River Breeder Reactor to a simulated hypothetical core-disruptive accident. These experiments provided quality data for validating treatments of the nonlinear fluid-structure interactions and many complex excursion phenomena, such as flow through perforated structures, large material distortions, multi-dimensional sliding interfaces, flow around sharp corners, and highly contorted fluid boundaries. Correlations of the predicted pressures with the test results of all gauges are made. Wave characteristics and arrival times are also compared. Results show that the ALICE-II code predicts the pressure profile well. Despite the complexity, the code gave good results for the SM-5 test
A Novel VOF-Type Volume-Tracking Method for Free-Surface Flows Based on Unstructured Triangular Mesh
Institute of Scientific and Technical Information of China (English)
JI Chun-ning; WANG Yuan-zhan; WANG Jian-feng
2005-01-01
A novel VOF-type volume-tracking method for two-dimensional free-surface flows based on the unstructured triangular mesh is presented. Owing to the inherent merit of the unstructured triangular mesh in fitting curved boundaries, this method can handle the free-surface problems with complex geometries accurately and directly, without introducing any complicated boundary treatment or artificial diffusion. The method solves the volume transport equation geometrically through the Modified Lagrangian-Eulerian Re-map (MLER) method, which is applied to advective fluid volumes. Moreover, the PLIC method is adopted to give a second-order reconstructed interface approximation. To validate this method, two advection tests were performed for the establishment of the accuracy and convergence rate of the solutions. Numerical results for these complex tests provide convincing evidence for the excellent solution quality and fidelity of the method.
Institute of Scientific and Technical Information of China (English)
崔涛; 张卫华; 孙帮成
2013-01-01
结合既有系统动力学分析方法和空气动力学研究方法,给出基于任意拉格朗日-欧拉法的高速列车与气流耦合振动的数值分析方法,包括离线耦合分析方法和在线耦合分析方法,在线耦合又可分为显式耦合分析方法和隐式耦合分析方法.介绍不同耦合分析方法在站台通过、高速交会、侧风等运行安全性方面的应用,考虑流固关系后,列车侧风安全性和交会安全性进一步降低.流固耦合数值分析方法在实例应用中得到直接或间接的验证,为高速列车流固关系研究提供1种方法和思路.%The new numeric analysis methodology based on Arbitrary Lagrangian-Eulerian(ALE) for high-speed train and airflow coupling vibration was presented by integrating the existing Finite Volume Method of Computational Fluid Dynamics and the numerical simulation method of Multi-Body Systems Dynamics.This methodology included off-line coupling and on-line coupling,and the latter included the explicit coupling method and implicit coupling method.The applications of these coupling methods in platform passing,high-speed crossing and side winds were introduced.Safety of train crossing and trains running in side winds was reduced when the coupling relationship of train system and airflow was taken into account.The methodology was verified in applications directly and indirectly.It offers a methodology and a idea for study of fluid-solid coupling relationship of high-speed trains.
International Nuclear Information System (INIS)
An evaluation method of the neutron fluence and mean spectrum with which samples have been irradiated is proposed. The principle is based on measuring the change of the isotopic abundance ratios of arbitrary pairs of nuclides having different neutron absorption cross sections for both thermal and intermediate neutrons. Advantages of the method are as follows, although sensitivity is lower than that of the ordinary activation method in a short irradiation period. i) Any sample can be used irrespective of irradiation history. ii) Nuclides present as impurities in samples can be used as detectors. iii) Neutron fluences and mean spectra with which samples have been heavily irradiated can be measured with reasonable accuracy, thus making it possible to offer the direct information to radiation damage studies. The present study deals with the principle and applicability of the method. (author)
Derrida model for arbitrary spin
Energy Technology Data Exchange (ETDEWEB)
Saakyan, D.B.
1988-04-01
The variant of the Kirkpatrick-Sherrington model generalized by Derrida for the case of arbitrary spin is considered. When the number of simultaneously interacting neighbors tends to infinity, a solution to the model is obtained not only by reduction to the random-energy model but also by means of the replica method with the Parisi ansatz.
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, H.; Iwamoto, K.; Saito, T.; Tachibana, M. [Iwate University, Iwate (Japan). Faculty of Engineering
1997-05-27
Methods to learn underground structures by utilizing the dispersion phenomenon of surface waves contained in microtremors include the frequency-wave number analysis method (the F-K method) and the spatial autocorrelation method (the SAC method). Despite the fact that the SAC method is capable of exploring structures at greater depths, the method is not utilized because of its stringent restriction in arrangement of seismometers during observation that they must be arranged evenly on the same circumference. In order to eliminate this restriction in the SAC method, a research group in the Hokuriku University has proposed an expanded spatial autocorrelation (ESAC) method. Using the concept of the ESAC method as its base, a method was realized to improve phase velocity estimation by making a simulation on an array shifted to the radius direction. As a result of the discussion, it was found that the proposed improvement method can be applied to places where waves come from a number of directions, such as urban areas. If the improvement method can be applied, the spatial autocorrelation function needs not be even in the circumferential direction. In other words, the SAC method can be applied to arbitrary arrays. 1 ref., 7 figs.
Optical arbitrary waveform characterization using linear spectrograms.
Jiang, Zhi; Leaird, Daniel E; Long, Christopher M; Boppart, Stephen A; Weiner, Andrew M
2010-08-01
We demonstrate the first application of linear spectrogram methods based on electro-optic phase modulation to characterize optical arbitrary waveforms generated under spectral line-by-line control. This approach offers both superior sensitivity and self-referencing capability for retrieval of periodic high repetition rate optical arbitrary waveforms.
Energy Technology Data Exchange (ETDEWEB)
Wong, Michael K. W.; Summers, Randall M.; Petney, Sharon Joy Victor; Luchini, Christopher Bernard; Drake, Richard Roy; Carroll, Susan K.; Hensinger, David M.; Garasi, Christopher Joseph; Robinson, Allen Conrad; Voth, Thomas Eugene; Haill, Thomas A.; Mehlhorn, Thomas Alan; Robbins, Joshua H.; Brunner, Thomas A.
2005-01-01
ALEGRA is an arbitrary Lagrangian-Eulerian multi-material finite element code used for modeling solid dynamics problems involving large distortion and shock propagation. This document describes the basic user input language and instructions for using the software.
Energy Technology Data Exchange (ETDEWEB)
Garasi, Christopher Joseph; Cochrane, Kyle Robert; Mehlhorn, Thomas Alan; Haill, Thomas A.; Summers, Randall M.; Robinson, Allen Conrad
2005-01-01
ALEGRA is an arbitrary Lagrangian-Eulerian finite element code that emphasizes large distortion and shock propagation in inviscid fluids and solids. This document describes user options for modeling resistive magnetohydrodynamic, thermal conduction, and radiation emission effects.
Energy Technology Data Exchange (ETDEWEB)
Garasi, Christopher Joseph; Haill, Thomas A.; Robinson, Allen Conrad
2003-11-01
ALEGRA is an arbitrary Lagrangian-Eulerian finite element code that emphasizes large distortion and shock propagation in inviscid fluids and solids. This document describes user options for modeling magnetohydrodynamic, thermal conduction, and radiation emission effects.
Currents for Arbitrary Helicity
Dragon, Norbert
2016-01-01
Using Mackey's classification of unitary representations of the Poincar\\'e group on massles states of arbitrary helicity we disprove the claim that states with helicity |h|>=1 cannot couple to a conserved current by constructing such a current.
Polarization Mode Dispersion Probability Distribution for Arbitrary Mode Coupling
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The probability distribution of the differential group delay for arbitrary mode coupling is simulated with Monte-Carlo method. Fitting the simulation results, we obtain probability distribution function for arbitrary mode coupling.
Analytic methods for ﬁeld induced tunneling in quantum wells with arbitrary potential proﬁles
Indian Academy of Sciences (India)
S Panda; B K Panda
2001-06-01
Electric ﬁeld induced tunneling is studied in three different types of quantum wells by solving time-independent effective mass equation in analytic methods based on three different Airy function approaches. Comparison of different Airy function methods indicates that they are identical and connected to each other by the Breit–Wigner formula.
Mei, Lijie; Wu, Xinyuan
2016-10-01
In general, extended Runge-Kutta-Nyström (ERKN) methods are more effective than traditional Runge-Kutta-Nyström (RKN) methods in dealing with oscillatory Hamiltonian systems. However, the theoretical analysis for ERKN methods, such as the order conditions, the symplectic conditions and the symmetric conditions, becomes much more complicated than that for RKN methods. Therefore, it is a bottleneck to construct high-order ERKN methods efficiently. In this paper, we first establish the ERKN group Ω for ERKN methods and the RKN group G for RKN methods, respectively. We then rigorously show that ERKN methods are a natural extension of RKN methods, that is, there exists an epimorphism η of the ERKN group Ω onto the RKN group G. This epimorphism gives a global insight into the structure of the ERKN group by the analysis of its kernel and the corresponding RKN group G. Meanwhile, we establish a particular mapping φ of G into Ω so that each image element is an ideal representative element of the congruence class in Ω. Furthermore, an elementary theoretical analysis shows that this map φ can preserve many structure-preserving properties, such as the order, the symmetry and the symplecticity. From the epimorphism η together with its section φ, we may gain knowledge about the structure of the ERKN group Ω via the RKN group G. In light of the theoretical analysis of this paper, we obtain high-order structure-preserving ERKN methods in an effective way for solving oscillatory Hamiltonian systems. Numerical experiments are carried out and the results are very promising, which strongly support our theoretical analysis presented in this paper.
International Nuclear Information System (INIS)
Using a combination of Runge-Kutta and Jacobi iterative method, we could solve the nonlinear Schroedinger equation describing the pulse propagation in FBGs. By decomposing the electric field to forward and backward components in fiber Bragg grating and utilizing the Fourier series analysis technique, the boundary value problem of a set of coupled equations governing the pulse propagation in FBG changes to an initial condition coupled equations which can be solved by simple Runge-Kutta method.
Kasimov, Nurlybek; Brown-Dymkoski, Eric; Vasilyev, Oleg V.
2015-11-01
A novel volume penalization method to enforce immersed boundary conditions in Navier-Stokes and Euler equations is presented. Previously, Brinkman penalization has been used to introduce solid obstacles modeled as porous media, although it is limited to Dirichlet-type conditions on velocity and temperature. This method builds upon Brinkman penalization by allowing Neumann conditions to be applied in a general fashion. Correct boundary conditions are achieved through characteristic propagation into the thin layer inside of the obstacle. Inward pointing characteristics ensure nonphysical solution inside the obstacle does not propagate outside to the fluid. Dirichlet boundary conditions are enforced similarly to Brinkman method. Penalization parameters act on a much faster timescale than the characteristic timescale of the flow. Main advantage of the method is systematic means of the error control. This talk is focused on the progress that was made towards the extension of the method to the 3D flows around irregular shapes. This work was supported by ONR MURI on Soil Blast Modeling.
Institute of Scientific and Technical Information of China (English)
Zuo Yan-Lei; Jiang Dong-Bin; Zhu Qi-Hua; Dong Jun; Zen Xiao-Ming; Huang Xiao-Jun; Huang Zheng
2012-01-01
We present a new method that can be used to calculate pulse-front distortion by measuring the spectral interference of two point-diffraction fields in their overlapped district.We demonstrate,for the first time,the measurement of the pulse-front distortion of the pulse from a complex multi-pass amplification system,which exists in almost all high-power laser systems,and obtain the irregular pulse-front distribution.The method presented does not need any reference light or assumption about the pulse-front distribution,and has an accuracy of several femtoseconds.
International Nuclear Information System (INIS)
We inquire into spin and pseudospin symmetries of the Dirac equation under a Moebius square-type potential using the Nikiforov-Uvarov method to calculate the bound state solutions. We numerically discuss the problem and include various explanatory figures. (authors)
Lamah, C. A.; Harris, W. L.
1983-01-01
A novel analytical-numerical method for calculating unsteady small disturbance transonic flow over airfoils has been developed. The method uses an extended integral equation technique, based on both the velocity potential and the acceleration potential, to predict unsteady aerodynamic loading on airfoils oscillating in subcritical transonic free stream conditions. The formulation is an extension of the work of Sivaneri and Harris (1980) for steady, non-lifting flows and utilizes the linear theory of Landahl (1961) for decoupling of steady and unsteady components. The analytical-numerical procedure involves several intnegrating schemes and applies to general frequencies of oscillations. The technique is illustrated by computing the transonic flow about parabolic arc airfoils. Specific unsteady results for reduced frequencies based on semi-chord of 0.01, 0.1, 0.3, 0.4 and 0.6 are given. Comparison of results with those obtained by an ADI finite difference scheme is made.
Moiseev, N. Ya.; Silant'eva, I. Yu.
2008-07-01
An approach to the construction of second-and higher order accurate difference schemes in time and space is described for solving the linear one-and multidimensional advection equations with constant coefficients by the Godunov method with antidiffusion. The differential approximations for schemes of up to the fifth order are constructed and written. For multidimensional advection equations with constant coefficients, it is shown that Godunov schemes with splitting over spatial variables are preferable, since they have a smaller truncation error than schemes without splitting. The high resolution and efficiency of the difference schemes are demonstrated using test computations.
Xue, Kan-Hao; Miao, Xiang-Shui
2016-01-01
The LDA-1/2 method expands Slater's half occupation technique to infinite solid state materials by introducing a self-energy potential centered at the anions to cancel the energy associated with electron-hole self-interaction. To avoid an infinite summation of long-ranged self-energy potentials they must be trimmed at a variationally-defined cutoff radius. The method has been successful in predicting accurate band gaps for a large number of elementary and binary semiconductors. Nevertheless, there has been some confusion regarding carbon and silicon, both in the cubic diamond structure, which require different ionizations of the valence charge, 1/2 for carbon and 1/4 for silicon respectively, to yield band gaps in agreement with experimental data. We here analyze the spatial distribution of the valence electrons of these two materials to conclude that in silicon and in carbon LDA-1/4 and LDA-1/2, respectively, must be adopted for the proper cancellation of the self-energies. Such analysis should be applied to...
Arbitrary Spin Galilean Oscillator
Hagen, C R
2014-01-01
The so-called Dirac oscillator was proposed as a modification of the free Dirac equation which reproduces many of the properties of the simple harmonic oscillator but accompanied by a strong spin-orbit coupling term. It has yet to be extended successfully to the arbitrary spin S case primarily because of the unwieldiness of general spin Lorentz invariant wave equations. It is shown here using the formalism of totally symmetric multispinors that the Dirac oscillator can, however, be made to accommodate spin by incorporating it into the framework of Galilean relativity. This is done explicitly for spin zero and spin one as special cases of the arbitrary spin result. For the general case it is shown that the coefficient of the spin-orbit term has a 1/S behavior by techniques which are virtually identical to those employed in the derivation of the g-factor carried out over four decades ago.
一种DDS任意波形发生器的ROM优化方法%A ROM optimization method of DDS-based arbitrary waveform generator
Institute of Scientific and Technical Information of China (English)
李超; 谢雪松; 张小玲
2013-01-01
This paper presents an improved method of arbitrary waveform generator based on direct digital frequency synthesis (DDS) technology achieved on field programmable gate array(FPGA). First, it writes the waveform data of triangle wave, sine wave, square wave, and ascending or descending sawtooth wave data to the off-chip memory, and moves the corresponding data into FPGA on-chip RAM when it is invoked, which replaces the traditional method that stores all types of waveform data in on-chip RAM sub-blocks. Then, it takes use of the symmetry of sine and triangle waveform in the four quadrants, and the linearity of the sawtooth waveform, process the waveform data and the address value by hardware inverter. It can restore the same-precision analog signal with a quarter of the amount of data. The overall storage capacity is reduced to 5% of the original design. After validation, this improved method is feasible, and it can greatly reduce the development costs.%提出了一种改进的基于直接频率合成技术(DDS)的任意波形发生器在现场可编程门阵列(FPGA)上的实现方法.首先将三角波、正弦波、方波和升/降锯齿波的波形数据写入片外存储器,当调用时再将相应的数据移入FPGA的片上RAM,取代分区块的将所有类型波形数据同时存储在片上RAM中的传统方法；再利用正弦波和三角波的波形在4个象限的对称性以及锯齿波的线性特性,通过硬件反相器对波形数据和寻址地址值进行处理,实现了以1/4的数据量还原出精度不变的模拟信号,从而将整体的存储量减小为原始设计方案的5％.经验证,这种改进方法正确可行,能够大大降低开发成本.
Computational fluid dynamic analysis of flutter characteristics for self-anchored suspension bridges
Institute of Scientific and Technical Information of China (English)
Zhiwen ZHU; Zhaoxiang WANG; Zhengqing CHEN
2008-01-01
This paper outlines the essentials and proce-dures of computational fluid dynamics (CFD) simulation applicable to evaluating flutter derivatives of bridge decks. An arbitrary Lagrangian-Eulerian (ALE) description of the flow around the moving rigid box girder combined with the finite volume discretization and multi-grid algorithm is pre-sented. The proposed methods are employed to identify flutter derivatives of the bridge deck of the Sanchaji Self-anchored Suspension Bridge. The results agree well with ones from wind tunnel tests. It demonstrates accuracy and efficiency of the present method.
Numerical simulation of fluid flow in a reheating furnace with multi-swirling-burners
Institute of Scientific and Technical Information of China (English)
Baowei Li; Zengwu Zhao; Yike Li; Wenfei Wu; Daqiang Cang
2003-01-01
A general numerical simulating program for three-dimensional (3-D) and time-dependent fluid flow for a reheating furnace with multi-swirling-burners has been developed based upon an arbitrary Lagrangian-Eulerian scheme (ALE) with the finite volume method. The parameters of fluid flow in a reheating furnace with multi-swirling-burners was calculated and the 3-D velocity distributions were obtained. The design of the burners was optimized for forming better swirling flow. The simulation shows that the fluid flow in the reheating furnace with the optimized burners is reasonable.
Simulation of a viscous fluid spreading by a bidimensional shallow water model
Di Martino, Bernard; Paoli, Jean-Martin; Simonnet, Pierre; 10.1016/j.apm.2011.01.015
2011-01-01
In this paper we propose a numerical method to solve the Cauchy problem based on the viscous shallow water equations in an horizontally moving domain. More precisely, we are interested in a flooding and drying model, used to modelize the overflow of a river or the intrusion of a tsunami on ground. We use a non conservative form of the two-dimensional shallow water equations, in eight velocity formulation and we build a numerical approximation, based on the Arbitrary Lagrangian Eulerian formulation, in order to compute the solution in the moving domain.
Universal properties of Fermi gases in arbitrary dimensions
DEFF Research Database (Denmark)
Valiente, Manuel; T. Zinner, Nikolaj; Molmer, Klaus
2012-01-01
We consider spin-1/2 Fermi gases in arbitrary, integer or non-integer spatial dimensions, interacting via a Dirac delta potential. We first generalize the method of Tan's distributions and implement short-range boundary conditions to arbitrary dimension and we obtain a set of universal relations...
Application of the VOF method based on unstructured quadrilateral mesh
Institute of Scientific and Technical Information of China (English)
JI Chun-ning; SHI Ying
2008-01-01
To simulate two-dimensional free-surface flows with complex boundaries directly and accurately, a novel VOF (Volume-of-fluid) method based on unstructured quadrilateral mesh is presented. Without introducing any complicated boundary treatment or artificial diffusion, this method treated curved boundaries directly by utilizing the inherent merit of unstructured mesh in fitting curves. The PLIC (Piecewise Linear Interface Calculation) method was adopted to obtain a second-order accurate linearized reconstruction approximation and the MLER (Modified Lagrangian-Eulerian Re-map) method was introduced to advect fluid volumes on unstructured mesh. Moreover, an analytical relation for the interface's line constant vs. the volume clipped by the interface was developed so as to improve the method's efficiency. To validate this method, a comprehensive series of large straining advection tests were performed. Numerical results provide convincing evidences for the method's high volume conservative accuracy and second-order shape error convergence rate. Also, a dramatic improvement on computational accuracy over its unstructured triangular mesh counterpart is checked.
Symmetric finite volume schemes for eigenvalue problems in arbitrary dimensions
Institute of Scientific and Technical Information of China (English)
DAI Xiaoying; YANG Zhang; ZHOU Aihui
2008-01-01
Based on a linear finite element space, two symmetric finite volume schemes for eigenvalue problems in arbitrary dimensions are constructed and analyzed. Some relationships between the finite element method and the finite difference method are addressed, too.
Symmetric finite volume schemes for eigenvalue problems in arbitrary dimensions
Institute of Scientific and Technical Information of China (English)
2008-01-01
Based on a linear finite element space,two symmetric finite volume schemes for eigenvalue problems in arbitrary dimensions are constructed and analyzed.Some relationships between the finite element method and the finite difference method are addressed,too.
Potential flow about arbitrary biplane wing sections
Garrick, I E
1937-01-01
A rigorous treatment is given of the problem of determining the two-dimensional potential flow around arbitrary biplane cellules. The analysis involves the use of elliptic functions and is sufficiently general to include the effects of such elements as the section shapes, the chord ratio, gap, stagger, and decalage, which elements may be specified arbitrarily. The flow problem is resolved by making use of the methods of conformal representation. Thus the solution of the problem of transforming conformally two arbitrary contours into two circles is expressed by a pair of simultaneous integral equations, for which a method of numerical solution is outlined. As an example of the numerical process, the pressure distribution over certain arrangements of the NACA 4412 airfoil in biplane combinations is presented and compared with the monoplane pressure distribution.
Strong field ionization in arbitrary laser polarizations
Protopapas, M.; Lappas, D. G.; Knight, P. L.
1997-01-01
We present a new method for investigating the nonperturbative quantum mechanical interaction of light with atoms in two dimensions, without a basis expansion. This enables us to investigate intense laser-atom interactions with light of arbitrary polarization without approximation, within the model restrictions. Results are presented for the dependence of ionization and high harmonic generation on ellipticity seen in recent experiments. Strong evidence of stabilization in circular polarization...
On Arbitrary Phases in Quantum Amplitude Amplification
Hoyer, P
2000-01-01
We consider the use of arbitrary phases in quantum amplitude amplification which is a generalization of quantum searching. We prove that the phase condition in amplitude amplification is given by $\\tan(\\phi/2)=\\tan(\\phi/2)(1-2a)$, where $\\phi$ and $\\phi$ are the phases used and where $a$ is the success probability of the given algorithm. Thus the choice of phases depends nontrivially and nonlinearly on the success probability. Utilizing this condition, we give methods for constructing quantum algorithms that succeed with certainty and for implementing arbitrary rotations. We also conclude that phase errors of order up to $\\frac{1}{\\sqrt{a}}$ can be tolerated in amplitude amplification.
The Interpretation of Saussure’s Arbitrariness
Institute of Scientific and Technical Information of China (English)
王艳
2015-01-01
According to Saussure,The arbitrary nature of language is"first principle of linguistic".With the development of cognitive science,some exaggerate the importance of iconicity;some even suggest iconicity should replace arbitrariness.What leads to this extreme view is the misunderstanding of arbitrariness.The paper aims at advocating an overall and objective view towards the arbitrary nature of language,putting forward that arbitrariness and iconicity are not incompatible but complementary.
Conformal array design on arbitrary polygon surface with transformation optics
Deng, Li; Wu, Yongle; Hong, Weijun; Zhu, Jianfeng; Peng, Biao; Li, Shufang
2016-06-01
A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.
Conformal array design on arbitrary polygon surface with transformation optics
Directory of Open Access Journals (Sweden)
Li Deng
2016-06-01
Full Text Available A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.
Institute of Scientific and Technical Information of China (English)
姚贞光; 刘巧芳
2014-01-01
无论是在实体足球比赛还是智能体机器人足球比赛中，近距离的任意球破门收益率较高。研究智能体足球机器人比赛的任意球轨迹修正和优化控制问题，进而指导足球训练提高任意球得分率。提出一种基于灰色靶关联分析的智能体任意球轨迹修正方法，首先对整个机器人足球的环境态势和球员行为体选择进行模型构建，然后给出了灰色靶关联分析的任意球轨迹修正算法，进行球体着力点和应力点的适应值分析，构建基于灰色靶关联分析的任意球应力衰减特性分析模型，指导任意球轨迹修正，最后在智能体足球世界杯3D仿真平台进行实验验证了算法的优越性能。实验结果得出，采用该算法能有效指导任意球发球着力点控制，优化任意球的攻击轨迹，提高智能体机器人足球的任意球进球成功率，预测和控制精度提高。%Either in the real football game or agent in the robot soccer competition, a free kick near distance and higher rate is perfect. Correction of arbitrary ball trajectory is researched for intelligent robot soccer competition and the optimal con⁃trol problem, and then guide the football training is proposed to improve the kick rate. A correction method of grey correla⁃tion analysis of agent is proposed based on arbitrary trajectory of the ball, first to the robot soccer environment situation and player behavior selection of model construction, and then gives the ball trajectory analysis of grey correlation algorithm, sphere to point and stress value analysis, construction of arbitrary ball analysis the grey target association based on the stress analysis model attenuation characteristics, guiding the ball trajectory correction, finally verify the superior perfor⁃mance of the algorithm in intelligent football World Cup in 3D simulation platform. Experimental results show that, the algo⁃rithm can effectively guide the
Representing Arbitrary Boosts for Undergraduates.
Frahm, Charles P.
1979-01-01
Presented is a derivation for the matrix representation of an arbitrary boost, a Lorentz transformation without rotation, suitable for undergraduate students with modest backgrounds in mathematics and relativity. The derivation uses standard vector and matrix techniques along with the well-known form for a special Lorentz transformation. (BT)
Institute of Scientific and Technical Information of China (English)
周岱; 何涛; 刘光众
2013-01-01
The combined interface boundary condition (CIBC) method has been developed as a remedy for time lag inherent in the loosely-coupled partitioned algorithm,whose correction terms for interfacial velocity and traction are introduced at two sequential time steps with a coupling parameter ω that plays an important part in the stability and accuracy of the coupled fluid-structure interaction system.However the structural traction rate that appears explicitly in the traction correction is estimated based on the solution of the structural subsystem,thus this handling needs the structural traction before it is corrected.In this paper a new formulation for the CIBC method is proposed to repair the foregoing inconvenience.The structural traction rate is removed via reformulating its correction term simply.Finally our new CIBC corrections request the structural traction no more,and are tuned by the ratio ω/△t that is served as the coupling parameter.The characteristic-based split (CBS) scheme is used to solve incompressible Navier-Stokes equations from the arbitrary Lagrangian-Eulerian viewpoint while the equation of rigid-body dynamics is solved by Newmark-β method.The moving submesh approach is performed for the fluid mesh deformation.For respecting geometric conservation law,a mass source term is implanted into the CBS scheme on the moving mesh.The rotational fluid-rigid body interaction is tested to validate the proposed methodology after discussing several numerical details.The obtained results are in good agreement with the existing data and some famous features of flow phenomena are exposed successfully.%针对流固耦合问题该文提出了一种改进结合界面边界条件方法,即通过重构界面修正公式,完全消除未经修正的拖曳力,引入新的耦合参数ω/△t以考虑时间步的影响.基于任意拉格朗日-欧拉有限元方法和弱耦合算法求解流固耦合系统.采用CBS(Characteristic-Based Split)稳定化流体有限元算
Institute of Scientific and Technical Information of China (English)
楼云锋; 杨颜志; 金先龙
2014-01-01
In order to study the seismic response of shallow diversion tunnel considering sloshing amplitude of the water, an analytical model of tunnel-soil-fluid is proposed taking account of nonlinear material behavior of soil, viscoelastic artificial boundary, the effective rigidity ratios and fluid-solid coupling. Firstly, the hoop, radial and axial structural rigidities of tunnel lining are obtained by numerical rigidity reduction tests. Furthermore, the orthotropic material is used in tunnel lining model. As an application, the seismic responses of a project of large-diameter parallel diversion tunnels, which is one of the key projects in Shanghai, are calculated using the multi-material arbitrary Lagrangian-Eulerian (ALE) method. The equivalent density method is then used to validate the established simulation model. Finally, two seismic input modes, the uniform and nonuniform excitations, are involved in the seismic analyses of the tunnel-soil-fluid system. The numerical results show that under horizontal earthquake excitation the influence of fluid on tunnel's displacement is small;however, the influences of fluid on both stress and deformation of the section are great. The tunnel moment are always focused on the position of the tunnel 45° cross-hatched. Comparing with the uniform seismic input, the results show that the nonuniform excitation can remarkably increase both displacement and deformation responses of the tunnel.%为研究浅埋输水隧道内部流体对隧道地震响应的影响，考虑黏弹性人工边界、土壤的非线性、隧道结构刚度有效率及流-固耦合作用，建立了双线隧道-土体-流体相互耦合作用的力学模型。通过刚度折减试验得到衬砌环环向、径向、轴向刚度，进而引入正交各向异性连续材料作为衬砌材料模型。采用基于任意拉格朗日-欧拉（ALE）描述法的流-固耦合方法，对上海某大直径双线输水隧道在流体作用下的地震响应进行了
International Nuclear Information System (INIS)
The mixed dual finite element method is usually used for the resolution of the SPN transport equations (simplified PN equations) in 3D homogenized geometries (composed by homogenized rectangles or hexagons). This method produces fast results with little memory requirements. We have extended the previous method to the treatment of unstructured geometries composed by quadrilaterals (for the moment limited to 2D), allowing us to treat geometries where fuel pins are exactly represented. The iterative resolution of the resulting matrix system is a generalization of the one already developed for the cartesian and the hexagonal geometries. In order to illustrate and to show the efficiency of this method, results on the NEA-C5G7-MOX benchmark are given. The previous benchmark has been extended for the hexagonal geometry and we provide here some results. This method is a first step towards the treatment of pin by pin core calculations without homogenization. The present solver is a prototype. It shows the efficiency of the method and it has to be extended to 3D calculations as well as to exact transport calculations. We also intend to extend the method to the treatment of unstructured geometries composed by quadrilaterals with curved edges (sectors of a circle).The iterative algorithm has yet to be accelerated using multigrid techniques through a coupling with the present homogenized solver (MINOS). In the future, it will be included in the next generation neutronic toolbox DESCARTES currently under development
Hill, P R
1958-01-01
A method of calculating the temperature of thick walls has been developed in which the time series and the response to a unit triangle variation of surface temperature concepts are used, together with essentially standard formulas for transient temperature and heat flow into thick walls. The method can be used without knowledge of the mathematical tools of its development. The method is particularly suitable for determining the wall temperature in one-dimensional thermal problems in aeronautics where there is a continuous variation of the heat-transfer coefficient and adiabatic-wall temperature. The method also offers a convenient means for solving the inverse problem of determining the heat-flow history when temperature history is known.
Arbitrary Bending Plasmonic Light Waves
Epstein, Itai
2013-01-01
We demonstrate the generation of self-accelerating surface plasmon beams along arbitrary caustic curvatures. These plasmonic beams are excited by free-space beams through a two-dimensional binary plasmonic phase mask, which provides the missing momentum between the two beams in the direction of propagation, and sets the required phase for the plasmonic beam in the transverse direction. We examine the cases of paraxial and non-paraxial curvatures and show that this highly versatile scheme can be designed to produce arbitrary plasmonic self-accelerating beams. Several different plasmonic beams, which accelerate along polynomial and exponential trajectories, are demonstrated both numerically and experimentally, with a direct measurement of the plasmonic light intensity using a near-field-scanning-optical-microscope.
Arbitrary bending plasmonic light waves.
Epstein, Itai; Arie, Ady
2014-01-17
We demonstrate the generation of self-accelerating surface plasmon beams along arbitrary caustic curvatures. These plasmonic beams are excited by free-space beams through a two-dimensional binary plasmonic phase mask, which provides the missing momentum between the two beams in the direction of propagation and sets the required phase for the plasmonic beam in the transverse direction. We examine the cases of paraxial and nonparaxial curvatures and show that this highly versatile scheme can be designed to produce arbitrary plasmonic self-accelerating beams. Several different plasmonic beams, which accelerate along polynomial and exponential trajectories, are demonstrated both numerically and experimentally, with a direct measurement of the plasmonic light intensity using a near-field scanning optical microscope.
Gomez-Sousa, Hipolito; Martinez-Lorenzo, Jose Angel; Arias-Acuña, Marcos
2015-01-01
This paper presents a new method, based on the well-known method of moments (MoM), for the numerical electromagnetic analysis of scattering and radiation from metallic or dielectric structures, or both structure types in the same simulation, that are in contact with other metallic or dielectric structures. The proposed method for solving the MoM junction problem consists of two separate algorithms, one of which comprises a generalization for bodies in contact of the surface integral equation (SIE) formulations. Unlike some other published SIE generalizations in the field of computational electromagnetics, this generalization does not require duplicating unknowns on the dielectric separation surfaces. Additionally, this generalization is applicable to any ordinary single-scatterer SIE formulations employed as baseline. The other algorithm deals with enforcing boundary conditions and Kirchhoff's Law, relating the surface current flow across a junction edge. Two important features inherent to this latter algorit...
Chang, T. S.
1974-01-01
A numerical scheme using the method of characteristics to calculate the flow properties and pressures behind decaying shock waves for materials under hypervelocity impact is developed. Time-consuming double interpolation subroutines are replaced by a technique based on orthogonal polynomial least square surface fits. Typical calculated results are given and compared with the double interpolation results. The complete computer program is included.
Application of CLEAR-VOF method to wave and flow simulations
Directory of Open Access Journals (Sweden)
Ying-wei SUN
2012-03-01
Full Text Available A two-dimensional numerical model based on the Navier-Stokes equations and computational Lagrangian-Eulerian advection remap-volume of fluid (CLEAR-VOF method was developed to simulate wave and flow problems. The Navier-Stokes equations were discretized with a three-step finite element method that has a third-order accuracy. In the CLEAR-VOF method, the VOF function F was calculated in the Lagrangian manner and allowed the complicated free surface to be accurately captured. The propagation of regular waves and solitary waves over a flat bottom, and shoaling and breaking of solitary waves on two different slopes were simulated with this model, and the numerical results agreed with experimental data and theoretical solutions. A benchmark test of dam-collapse flow was also simulated with an unstructured mesh, and the capability of the present model for wave and flow simulations with unstructured meshes, was verified. The results show that the model is effective for numerical simulation of wave and flow problems with both structured and unstructured meshes.
Simulation of Marine Hydrokinetic Turbines in Unsteady Flow using Vortex Particle Method
Sale, Danny; Aliseda, Alberto
2013-11-01
A vortex particle method has been developed to study the performance and wake characteristics of Marine Hydrokinetic turbines. The goals are to understand mean flow and turbulent eddy effects on wake evolution, and the unsteady loading on the rotor and support structures. The vorticity-velocity formulation of the Navier-Stokes equations are solved using a hybrid Lagrangian-Eulerian method involving both vortex particle and spatial mesh discretizations. Particle strengths are modified by vortex stretching, diffusion, and body forces; these terms in the vorticity transport equation involve differential operators and are computed more efficiently on a Cartesian mesh using finite differences. High-order and moment-conserving interpolations allow the particles and mesh to exchange field quantities and particle strengths. An immersed boundary method which introduces a penalization term in the vorticity transport equations provides an efficient way to satisfy the no-slip boundary condition on solid boundaries. To provide further computational speedup, we investigate the use of multicore processors and graphics processing units using the OpenMP and OpenCL interfaces within the Parallel Particle-Mesh Library.
Joint Signal Polarization and DOA Estimation Method for Arbitrary Array%一种适用于任意阵列的极化和二维DOA联合估计算法
Institute of Scientific and Technical Information of China (English)
郑均杰; 刘国峰; 王晓东
2014-01-01
提出了一种适用于任意阵列的极化和二维DOA联合估计算法。该算法基于信号空时二维结构特征，利用空域采样和时域采样构造时空矩阵，通过DOA矩阵方法进行极化和二维DOA参数估计，不需要二维谱峰搜索，计算量小。仿真实验证明了算法的有效性。%A joint estimation method of polarization and 2D (two-dimensional) DOA was proposed for arbitrary array. Based on the space-time eigenstructure of signals, space-time matrixes were constructed by spatial domain sampling and time domain sampling. The DOA matrix method was utilized to estimate the parameters in this method. It doesn't need spectral peak searching and complex computation. The simulation validated effectiveness of this method.
Sampling to estimate arbitrary subset sums
Duffield, Nick; Lund, Carsten; Thorup, Mikkel
2005-01-01
Starting with a set of weighted items, we want to create a generic sample of a certain size that we can later use to estimate the total weight of arbitrary subsets. For this purpose, we propose priority sampling which tested on Internet data performed better than previous methods by orders of magnitude. Priority sampling is simple to define and implement: we consider a steam of items i=0,...,n-1 with weights w_i. For each item i, we generate a random number r_i in (0,1) and create a priority ...
Garbage-free reversible constant multipliers for arbitrary integers
DEFF Research Database (Denmark)
Mogensen, Torben Ægidius
2013-01-01
We present a method for constructing reversible circuitry for multiplying integers by arbitrary integer constants. The method is based on Mealy machines and gives circuits whose size are (in the worst case) linear in the size of the constant. This makes the method unsuitable for large constants, ......, but gives quite compact circuits for small constants. The circuits use no garbage or ancillary lines....
High order methods for incompressible fluid flow: Application to moving boundary problems
Energy Technology Data Exchange (ETDEWEB)
Bjoentegaard, Tormod
2008-04-15
Fluid flows with moving boundaries are encountered in a large number of real life situations, with two such types being fluid-structure interaction and free-surface flows. Fluid-structure phenomena are for instance apparent in many hydrodynamic applications; wave effects on offshore structures, sloshing and fluid induced vibrations, and aeroelasticity; flutter and dynamic response. Free-surface flows can be considered as a special case of a fluid-fluid interaction where one of the fluids are practically inviscid, such as air. This type of flows arise in many disciplines such as marine hydrodynamics, chemical engineering, material processing, and geophysics. The driving forces for free-surface flows may be of large scale such as gravity or inertial forces, or forces due to surface tension which operate on a much smaller scale. Free-surface flows with surface tension as a driving mechanism include the flow of bubbles and droplets, and the evolution of capillary waves. In this work we consider incompressible fluid flow, which are governed by the incompressible Navier-Stokes equations. There are several challenges when simulating moving boundary problems numerically, and these include - Spatial discretization - Temporal discretization - Imposition of boundary conditions - Solution strategy for the linear equations. These are some of the issues which will be addressed in this introduction. We will first formulate the problem in the arbitrary Lagrangian-Eulerian framework, and introduce the weak formulation of the problem. Next, we discuss the spatial and temporal discretization before we move to the imposition of surface tension boundary conditions. In the final section we discuss the solution of the resulting linear system of equations. (Author). refs., figs., tabs
Simulation of Free Airfoil Vibrations in Incompressible Viscous Flow — Comparison of FEM and FVM
Directory of Open Access Journals (Sweden)
Petr Sváček
2012-01-01
Full Text Available This paper deals with a numerical solution of the interaction of two-dimensional (2-D incompressible viscous flow and a vibrating profile NACA 0012 with large amplitudes. The laminar flow is described by the Navier-Stokes equations in the arbitrary Lagrangian-Eulerian form. The profile with two degrees of freedom (2-DOF can rotate around its elastic axis and oscillate in the vertical direction. Its motion is described by a nonlinear system of two ordinary differential equations. Deformations of the computational domain due to the profile motion are treated by the arbitrary Lagrangian-Eulerianmethod. The finite volume method and the finite element method are applied, and the numerical results are compared.
electrode of an arbitrary shape
Directory of Open Access Journals (Sweden)
P. A. Krutitskii
1999-01-01
Full Text Available A problem on electric current in a semiconductor film from an electrode of an arbitrary shape is studied in the presence of a magnetic field. This situation describes the Hall effect, which indicates the deflection of electric, current from electric field in a semiconductor. From mathematical standpoint we consider the skew derivative problem for harmonic functions in the exterior of an open arc in a plane. By means of potential theory the problem is reduced to the Cauchy singular integral equation and next to the Fredholm equation of the 2nd kind which is uniquely solvable. The solution of the integral equation can be computed by standard codes by discretization and inversion of the matrix. The uniqueness and existence theorems are formulated.
Surface waves on arbitrary vertically-sheared currents
Smeltzer, Benjamin K
2016-01-01
We study dispersion properties of linear surface gravity waves propagating in an arbitrary direction atop a current profile of arbitrary depth-varying magnitude using a piecewise linear approximation, and develop a robust numerical framework for practical calculation. The method has been much used in the past in 2D, and we herein extend and apply it to 3D problems. Being valid for all wavelengths without loss of accuracy, the scheme is particularly well suited to solve problems involving Fourier transformations in the horizontal plane. We examine the group and phase velocities over different wavelength regimes and current profiles, highlighting characteristics due to the depth-variable vorticity. We show an example application to ship waves on an arbitrary current profile, and demonstrate qualitative differences in the wake patterns between a concave down profile when compared to a constant shear profile with equal depth-averaged vorticity. New insight is given concerning the nature of extra spurious solution...
Probabilistic Teleportation of an Arbitrary n-Particle Entangled State
Institute of Scientific and Technical Information of China (English)
XIYong-Jun; FANGJian-Xing; ZHUShi-Qun; GUOZhan-Ying
2005-01-01
A scheme for teleporting an arbitrary n-particle entangled state via n pairs of non-maximally entangled states is proposed. The probability of successful teleportation is determined only by the smaller coefficients of the partially entangled pairs. The method is very easy to be realized.
Energy Technology Data Exchange (ETDEWEB)
Garasi, Christopher Joseph; Cochrane, Kyle Robert; Mehlhorn, Thomas Alan; Haill, Thomas A.; Brunner, Thomas A.; Summers, Randall M.; Robinson, Allen Conrad
2005-02-01
ALEGRA is an arbitrary Lagrangian-Eulerian finite element code that emphasizes large distortion and shock propagation in inviscid fluids and solids. This document describes user options for modeling resistive magnetohydrodynamics, thermal conduction, and radiation transport effects, and two material temperature physics.
Energy Technology Data Exchange (ETDEWEB)
Barham, M; White, D; Steigmann, D; Rudd, R
2009-04-08
Recently a new class of biocompatible elastic polymers loaded with small ferrous particles (magnetoelastomer) was developed at Lawrence Livermore National Laboratory. This new material was formed as a thin film using spin casting. The deformation of this material using a magnetic field has many possible applications to microfluidics. Two methods will be used to calculate the deformation of a circular magneto-elastomeric film subjected to a magnetic field. The first method is an arbitrary Lagrangian-Eulerian (ALE) finite element method (FEM) and the second is based on nonlinear continuum electromagnetism and continuum elasticity in the membrane limit. The comparison of these two methods is used to test/validate the finite element method.
ON THE SCATTERING OF ARBITRARY SHAPE MICROSTRIP PATCH
Institute of Scientific and Technical Information of China (English)
He Xiulian; Gong Shuxi; Liu Qizhong
2004-01-01
In this letter, discrete complex image method is employed to compute the Green's functions in the spatial domain, which improves the speed of evaluating the impedance matrix.The triangle vector basis function--RWG, is used to simulate the current distribution in order to compute the scattering properties of arbitrary shape microstrip patch without the staircase approximation. The numerical result shows the validity of the proposed method.
Arbitrary Finite-time Tracking Control for Magnetic Levitation Systems
Xuan-Toa Tran; Hee-Jun Kang
2014-01-01
In this paper, an arbitrary finite-time tracking control (AFTC) method is developed for magnetic levitation systems with uncertain dynamics and external disturbances. By introducing a novel augmented sliding- mode manifold function, the proposed method can eliminate the singular problem in traditional terminal sliding-mode control, as well as the reaching-phase problem. Moreover, the tracking errors can reach the reference value with faster convergence and better tracking precision in arbitra...
Positive Gravitattional Energy in Arbitrary Dimensions
Choquet-Bruhat, Yvonne
2011-01-01
We present a streamlined, complete proof, valid in arbitrary space dimension $n$, and using only spinors on the oriented Riemannian space $(M^{n};g),$ of the positive energy theorem in General Relativity.
Arbitrary orbital angular momentum of photons
Pan, Yue; Ren, Zhi-Cheng; Wang, Xi-Lin; Tu, Chenghou; Li, Yongnan; Wang, Hui-Tian
2015-01-01
Orbital angular momentum (OAM) of photons, as a new fundamental degree of freedom, has excited a great diversity of interest, because of a variety of emerging applications. Arbitrarily tunable OAM has gained much attention, but its creation remains still a tremendous challenge. We demonstrate the realization of well-controlled arbitrary OAM in both theory and experiment. We present the concept of general OAM, which extends the OAM carried by the scalar vortex field to the OAM carried by the azimuthally varying polarized vector field. The arbitrary OAM has the same characteristics as the well-defined integer OAM: intrinsic OAM, uniform local OAM and intensity ring, and propagation stability. The arbitrary OAM has unique natures: it is allowed to be flexibly tailored and the radius of the focusing ring can have various choices for a desired OAM, which are of great significance to the benefit of surprising applications of the arbitrary OAM.
THE EIGENVALUE PERTURBATION BOUND FOR ARBITRARY MATRICES
Institute of Scientific and Technical Information of China (English)
Wen Li; Jian-xin Chen
2006-01-01
In this paper we present some new absolute and relative perturbation bounds for the eigenvalue for arbitrary matrices, which improves some recent results. The eigenvalue inclusion region is also discussed.
Oger, G.; Marrone, S.; Le Touzé, D.; de Leffe, M.
2016-05-01
This paper addresses the accuracy of the weakly-compressible SPH method. Interpolation defects due to the presence of anisotropic particle structures inherent to the Lagrangian character of the Smoothed Particle Hydrodynamics (SPH) method are highlighted. To avoid the appearance of these structures which are detrimental to the quality of the simulations, a specific transport velocity is introduced and its inclusion within an Arbitrary Lagrangian Eulerian (ALE) formalism is described. Unlike most of existing particle disordering/shifting methods, this formalism avoids the formation of these anisotropic structures while a full consistency with the original Euler or Navier-Stokes equations is maintained. The gain in accuracy, convergence and numerical diffusion of this formalism is shown and discussed through its application to various challenging test cases.
Numerical simulation of airflow through the model of oscillating vocal folds
Directory of Open Access Journals (Sweden)
Prokopová J.
2010-12-01
Full Text Available This work deals with numerical simulation of flow in time-dependent 2D domains with a special interest in medical applications to airflow in human vocal folds. The mathematical model of this process is described by the compressible Navier-Stokes equations. For the treatment of the time-dependent domain, the Arbitrary Lagrangian-Eulerian (ALE method is used. The discontinuous Galerkin finite element method (DGFEM is used for the space semidiscretization of the governing equations in the ALE formulation. The time discretization is carried out with the aid of a linearized semi-implicit method with good stability properties. We present some computational results for flow in a channel with a prescribed periodic motion of a part of the channel walls.
A fast algorithm for simulating multiphase flows through periodic geometries of arbitrary shape
Marple, Gary; Barnett, Alex; Gillman, Adrianna; Veerapaneni, Shravan
2015-01-01
This paper presents a new boundary integral equation (BIE) method for simulating particulate and multiphase flows through periodic channels of arbitrary smooth shape in two dimensions. The authors consider a particular system---multiple vesicles suspended in a periodic channel of arbitrary shape---to describe the numerical method and test its performance. Rather than relying on the periodic Green's function as classical BIE methods do, the method combines the free-space Green's function with ...
International Nuclear Information System (INIS)
Matrix diffusion, a diffusive mass transfer process,in the structured soils and geologic units at ORNL, is believe to be an important subsurface mass transfer mechanism; it may affect off-site movement of radioactive wastes and remediation of waste disposal sites by locally exchanging wastes between soil/rock matrix and macropores/fractures. Advective mass transfer also contributes to waste movement but is largely neglected by researchers. This report presents the first documented 2-D multiregion solute transport code (MURT) that incorporates not only diffusive but also advective mass transfer and can be applied to heterogeneous porous media under transient flow conditions. In this report, theoretical background is reviewed and the derivation of multiregion solute transport equations is presented. Similar to MURF (Gwo et al. 1994), a multiregion subsurface flow code, multiplepore domains as suggested by previous investigators (eg, Wilson and Luxmoore 1988) can be implemented in MURT. Transient or steady-state flow fields of the pore domains can be either calculated by MURF or by modelers. The mass transfer process is briefly discussed through a three-pore-region multiregion solute transport mechanism. Mass transfer equations that describe mass flux across pore region interfaces are also presented and parameters needed to calculate mass transfer coefficients detailed. Three applications of MURT (tracer injection problem, sensitivity analysis of advective and diffusive mass transfer, hillslope ponding infiltration and secondary source problem) were simulated and results discussed. Program structure of MURT and functions of MURT subroutiness are discussed so that users can adapt the code; guides for input data preparation are provided in appendices
Analysis and numerical simulation of dynamic effect on rock under high pressure water jet
Institute of Scientific and Technical Information of China (English)
LI Xiao-hong; SI Hu; WANG Dan-dan
2008-01-01
Based on continuum mechanics and rock dynamics, analyzed the micro-structure damage of rock and the impulsive effect under high pressure water jet and developed the dynamic model. Further, on the assumption of that rock was homogeneous and isotropic, a computational model was established based on nonlinear finite element and Arbitrary Lagrangian-Eulerian(ALE) method. The dynamic effect impacted on rock under high pressure water jet was simulated by the dynamic contact method. The propagation of stress wave in rock was numerically simulated at different impacting velocity. The results show that the propagation velocity of stress wave is proportional to the impacting velocity of high pressure water jet. The faster the impacting velocity is, the quicker the comedown of stress wave.
On the computation of multi-material flows using ALE formulation
International Nuclear Information System (INIS)
Computation of compressible multi-fluid flows with a general equation of state using interface tracking and moving grid approach is discussed in this paper. The AUSM+, HLLC, and Godunov methods are presented and implemented in the context of arbitrary Lagrangian-Eulerian formulation for solving the unsteady compressible Euler equations. The developed methods are fully conservative, and used to compute a variety of multi-component flow problems, where the equations of state can be drastically different and stiff. Numerical results indicate that both ALE HLLC and Godunov schemes demonstrate their simplicity and robustness for solving such multi-phase flow problems, and yet ALE AUSM+ scheme exhibits strong oscillations around material interfaces even using a first order monotone scheme and therefore is not suitable for this class of problems
LES of non-evaporative diesel fuel spray
Energy Technology Data Exchange (ETDEWEB)
Jonnalagedda, S.; Zhou, B. [Windsor Univ., ON (Canada). Dept. of Mechanical, Automotive and Materials Engineering
2009-07-01
Mixture formation and fluid flow in internal combustion engines are unsteady and anisotropic due to the engine's complex geometry, piston movement, flow rotation, and 2-phase mixing. The wide range of eddy sizes in turbulent flow enhances turbulence mixing. In this study, a large eddy simulation (LES) was used to characterize the turbulent unsteady structure of diesel fuel spray. A 1-equation LES model was implemented in a KIVA solver based on arbitrary Lagrangian Eulerian methods. Predictions obtained using the method were then compared with Navier Stokes simulations of transient, 2-, and 3-dimensional reactive fluid flows. Results of the study indicated that the LES approach accurately characterized the inhomogenous, unsteady structure of the fuel spray. Spray tip penetration and spray structure and vector plots were compared. Results were more accurate than those obtained using a Reynolds Averaged Navier-Stokes (RANS) approach. 5 refs., 3 tabs., 7 figs.
Large deformation finite element analysis of undrained pile installation
Konkol, Jakub; Bałachowski, Lech
2016-03-01
In this paper, a numerical undrained analysis of pile jacking into the subsoil using Abaqus software suit has been presented. Two different approaches, including traditional Finite Element Method (FEM) and Arbitrary Lagrangian-Eulerian (ALE) formulation, were tested. In the first method, the soil was modelled as a two-phase medium and effective stress analysis was performed. In the second one (ALE), a single-phase medium was assumed and total stress analysis was carried out. The fitting between effective stress parameters and total stress parameters has been presented and both solutions have been compared. The results, discussion and verification of numerical analyzes have been introduced. Possible applications and limitations of large deformation modelling techniques have been explained.
Mola, Andrea; DeSimone, Antonio
2012-01-01
We present an innovative numerical discretization of the equations of inviscid potential flow for the simulation of three dimensional unsteady and nonlinear water waves generated by a ship hull advancing in water. The equations of motion are written in a semi-Lagrangian framework, and the resulting integro-differential equations are discretized in space via an adaptive iso-parametric collocation Boundary Element Method, and in time via adaptive implicit Backward Differentiation Formulas (BDF) with variable step and variable order. When the velocity of the advancing ship hull is non-negligible, the semi-Lagrangian formulation (also known as Arbitrary Lagrangian Eulerian formulation, or ALE) of the free surface equations contains dominant transport terms which are stabilized with a Streamwise Upwind Petrov-Galerkin (SUPG) method. The SUPG stabilization allows automatic and robust adaptation of the spatial discretization with unstructured quadrilateral grids. Preliminary results are presented where we compare ou...
The arbitrary l continuum states of the hyperbolic molecular potential
Energy Technology Data Exchange (ETDEWEB)
Wei, Gao-Feng, E-mail: fgwei_2000@163.com [School of Physics and Mechatronics Engineering, Xi' an University of Arts and Science, Xi' an 710065 (China); Chen, Wen-Li, E-mail: physwlchen@163.com [Department of Basic Science, Xi' an Peihua University, Xi' an 710065 (China); Dong, Shi-Hai, E-mail: dongsh2@yahoo.com [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edificio 9, Unidad Profesional Adolfo López Mateos, Mexico D.F. 07738 (Mexico); Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)
2014-06-27
Within the framework of partial-wave method, we study in this Letter the arbitrary l continuum states of the Schrödinger equation with the hyperbolic molecular potential in terms of an improved approximation to the centrifugal term. We present the normalized radial wave functions and obtain analytical formula of phase shifts. In addition, the corresponding bound states are also discussed by studying the analytical properties of the scattering amplitude. We calculate the energy spectra and scattering phase shifts by the improved, previous approximations and the accurate methods, respectively and find that the improved approximation is better than the previous one since the present results are in better agreement with the accurate ones. - Highlights: • The hyperbolic potential with arbitrary l state is solved. • Improved approximation to centrifugal term is used. • Phase shift formula is derived analytically. • Accurate results are compared with the present results.
Numerical modeling of pulsed laser-material interaction and of laser plume dynamics
Energy Technology Data Exchange (ETDEWEB)
Zhao, Qiang; Shi, Yina [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)
2015-03-10
We have developed two-dimensional Arbitrary Lagrangian Eulerian (ALE) code which is used to study the physical processes, the plasma absorption, the crater profile, and the temperature distribution on metallic target and below the surface. The ALE method overcomes problems with Lagrangian moving mesh distortion by mesh smoothing and conservative quantities remapping from Lagrangian mesh to smoothed one. A new second order accurate diffusion solver has been implemented for the thermal conduction and radiation transport on distorted mesh. The results of numerical simulation of pulsed laser ablation are presented. The influences of different processes, such as time evolution of the surface temperature, interspecies interactions (elastic collisions, recombination-dissociation reaction), interaction with an ambient gas are examined. The study presents particular interest for the analysis of experimental results obtained during pulsed laser ablation.
Trajectory approach to the Schrödinger-Langevin equation with linear dissipation for ground states
Chou, Chia-Chun
2015-11-01
The Schrödinger-Langevin equation with linear dissipation is integrated by propagating an ensemble of Bohmian trajectories for the ground state of quantum systems. Substituting the wave function expressed in terms of the complex action into the Schrödinger-Langevin equation yields the complex quantum Hamilton-Jacobi equation with linear dissipation. We transform this equation into the arbitrary Lagrangian-Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation is simultaneously integrated with the trajectory guidance equation. Then, the computational method is applied to the harmonic oscillator, the double well potential, and the ground vibrational state of methyl iodide. The excellent agreement between the computational and the exact results for the ground state energies and wave functions shows that this study provides a synthetic trajectory approach to the ground state of quantum systems.
Time-discrete higher order ALE formulations: a priori error analysis
Bonito, Andrea
2013-03-16
We derive optimal a priori error estimates for discontinuous Galerkin (dG) time discrete schemes of any order applied to an advection-diffusion model defined on moving domains and written in the Arbitrary Lagrangian Eulerian (ALE) framework. Our estimates hold without any restrictions on the time steps for dG with exact integration or Reynolds\\' quadrature. They involve a mild restriction on the time steps for the practical Runge-Kutta-Radau methods of any order. The key ingredients are the stability results shown earlier in Bonito et al. (Time-discrete higher order ALE formulations: stability, 2013) along with a novel ALE projection. Numerical experiments illustrate and complement our theoretical results. © 2013 Springer-Verlag Berlin Heidelberg.
Energy Technology Data Exchange (ETDEWEB)
Kamm, James R.; Love, Edward; Robinson, Allen C; Young, Joseph G.; Ridzal, Denis
2013-12-01
We review the edge element formulation for describing the kinematics of hyperelastic solids. This approach is used to frame the problem of remapping the inverse deformation gradient for Arbitrary Lagrangian-Eulerian (ALE) simulations of solid dynamics. For hyperelastic materials, the stress state is completely determined by the deformation gradient, so remapping this quantity effectively updates the stress state of the material. A method, inspired by the constrained transport remap in electromagnetics, is reviewed, according to which the zero-curl constraint on the inverse deformation gradient is implicitly satisfied. Open issues related to the accuracy of this approach are identified. An optimization-based approach is implemented to enforce positivity of the determinant of the deformation gradient. The efficacy of this approach is illustrated with numerical examples.
Farhat, Charbel; Geuzaine, Philippe; Grandmont, Céline
2001-12-01
Discrete geometric conservation laws (DGCLs) govern the geometric parameters of numerical schemes designed for the solution of unsteady flow problems on moving grids. A DGCL requires that these geometric parameters, which include among others grid positions and velocities, be computed so that the corresponding numerical scheme reproduces exactly a constant solution. Sometimes, this requirement affects the intrinsic design of an arbitrary Lagrangian Eulerian (ALE) solution method. In this paper, we show for sample ALE schemes that satisfying the corresponding DGCL is a necessary and sufficient condition for a numerical scheme to preserve the nonlinear stability of its fixed grid counterpart. We also highlight the impact of this theoretical result on practical applications of computational fluid dynamics.
Arbitrary rotation and entanglement of flux SQUID qubits
Kis, Z
2003-01-01
We propose a new approach for the arbitrary rotation of a three-level SQUID qubit and describe a new strategy for the creation of coherence transfer and entangled states between two three-level SQUID qubits. The former is succeeded by exploring the coupled-uncoupled states of the system when irradiated with two microwave pulses, and the latter is succeeded by placing the SQUID qubits into a microwave cavity and used adiabatic passage methods for their manipulation.
Axial Anomaly in Lattice Abelian Gauge Theory in Arbitrary Dimensions
Fujiwara, T; Wu, K; Fujiwara, Takanori; Suzuki, Hiroshi; Wu, Ke
1999-01-01
Axial anomaly of lattice abelian gauge theory in hyper-cubic regular lattice in arbitrary even dimensions is investigated by applying the method of exterior differential calculus. The topological invariance, gauge invariance and locality of the axial anomaly determine the explicit form of the topological part. The anomaly is obtained up to a multiplicative constant for finite lattice spacing and can be interpreted as the Chern character of the abelian lattice gauge theory.
Statistical Reconstruction of arbitrary spin states of particles: root approach
Bogdanov, Yu. I.
2005-01-01
A method of quantum tomography of arbitrary spin particle states is developed on the basis of the root approach. It is shown that the set of mutually complementary distributions of angular momentum projections can be naturally described by a set of basis functions based on the Kravchuk polynomials. The set of Kravchuk basis functions leads to a multi-parametric statistical distribution that generalizes the binomial distribution. In order to analyze a statistical inverse problem of quantum mec...
Electrodynamics in Arbitrary Reference Frames and in Arbitrary Material Media
International Nuclear Information System (INIS)
Full text: The investigation of electromagnetic phenomena in material media still belongs to the most difficult tasks of electrodynamics. Complexity and variability of material media practically exclude effective applications of methods and computational techniques elaborated in the framework of standard microscopic electrodynamics with classical vacuum as a ground state. In order to obtain satisfactorily exact descriptions of electromagnetic properties of complex material media one is enforced to use methods and approximations which are difficult to control. Moreover, they usually break covariance properties and the results obtained are valid in one reference frame which choice remains subjective and model dependent. Some time ago we have proposed a reformulation of Maxwell electrodynamics which opens new ways in study of electromagnetic processes in material media. The formalism gets rid of assumptions characteristic for vacuum electrodynamics only and it avoids the usage of constitutive relations as primary relations put on quantities needed for a complete description of an electromagnetic system. Fundamental properties of all electromagnetic quantities are their uniquely defined transformation rules and their analysis allows to determine the possible relations between them. Within such a scheme it is possible to introduce constitutive relations which do not have analogies in macroscopic classical electrodynamics. They may be used in description of microscopic electromagnetic processes in a different way than it is done in the framework of quantum electrodynamics. (author)
Perturbation Theory for Arbitrary Coupling Strength ?
Mahapatra, B P
2016-01-01
We demonstrate Borel summability for arbitrary coupling strength in a new formulation of perturbation theory (designated here as "Mean Field Perturbation Theory (MFPT)") by applying it to one dimensional anharmonic-interactions, which includes the case of the quartic and sextic anharmonic oscillators(AHO) and the quartic double-well-oscillator (QDWO).It is well known that the perturbation-series is not Borel-summable for the QDWO in the standard formulation of perturbation theory(SFPT). In contrast, MFPT leads to a Borel-summable perturbation series and accurate values for the energy-spectra for arbitrary (physical) value of the coupling strength in each case as stated above. The general nature and the simplicity of the formulation underlying MFPT leads us to conjecture that this scheme may be applicable to arbitrary interactions in quantum theory.
Universal properties of Fermi gases in arbitrary dimensions
Valiente, Manuel; Molmer, Klaus
2012-01-01
We consider spin-1/2 Fermi gases in arbitrary, integer or non-integer spatial dimensions, interacting via a Dirac delta potential. We first generalize the method of Tan's distributions and implement short-range boundary conditions to arbitrary dimension and we obtain a set of universal relations for the Fermi gas, which serve as dimensional interpolation/extrapolation formulae in between integer dimensions. We show that, under very general conditions, effective reduced-dimensional scattering lengths due to transversal confinement depend on the original three-dimensional scattering length in a universal way. As a direct consequence, we find that confinement-induced resonances occur in all dimensions different from D=2, without any need to solve the associated multichannel scattering problem. Finally, we show that reduced-dimensional contacts --- related to the tails of the momentum distributions --- are connected to the actual three-dimensional contact through a correction factor of purely geometric origin.
Optimizing the controllability of arbitrary networks with genetic algorithm
Li, Xin-Feng; Lu, Zhe-Ming
2016-04-01
Recently, as the controllability of complex networks attracts much attention, how to optimize networks' controllability has become a common and urgent problem. In this paper, we develop an efficient genetic algorithm oriented optimization tool to optimize the controllability of arbitrary networks consisting of both state nodes and control nodes under Popov-Belevitch-Hautus rank condition. The experimental results on a number of benchmark networks show the effectiveness of this method and the evolution of network topology is captured. Furthermore, we explore how network structure affects its controllability and find that the sparser a network is, the more control nodes are needed to control it and the larger the differences between node degrees, the more control nodes are needed to achieve the full control. Our framework provides an alternative to controllability optimization and can be applied to arbitrary networks without any limitations.
Generation of Electromagnetic Waves with Arbitrary Orbital Angular Momentum Modes
Cheng, Li; Hong, Wei; Hao, Zhang-Cheng
2014-01-01
Recently, much attention has been focused on beams carrying orbital angular momentum (OAM) for radio communication. Here we experimentally demonstrate a planar-spiral phase plate (planar-SPP) for generating arbitrary mixed OAM beams. This proposed planar-SPP uses the concept of transmit array antenna having a perforated substrate to control the outputting phase for generating beams carrying OAM with arbitrary modes. As demonstrations, three planar-SPPs with a single OAM mode and two mixed OAM modes around 94 GHz have been investigated with design and experiments in this paper, respectively. The typical experimental intensity and phase patterns show that the proposed method of generating OAM beams really works. PMID:24770669
Estimating False Discovery Proportion Under Arbitrary Covariance Dependence
Fan, Jianqing; Gu, Weijie
2011-01-01
Multiple hypothesis testing is a fundamental problem in high dimensional inference, with wide applications in many scientific fields. In genome-wide association studies, tens of thousands of tests are performed simultaneously to find if any SNPs are associated with some traits and those tests are correlated. When test statistics are correlated, false discovery control becomes very challenging under arbitrary dependence. In the current paper, we propose a novel method based on principal factor approximation, which successfully subtracts the common dependence and weakens significantly the correlation structure, to deal with an arbitrary dependence structure. We derive an approximate expression for false discovery proportion (FDP) in large scale multiple testing when a common threshold is used and provide a consistent estimate of realized FDP. This result has important applications in controlling FDR and FDP. Our estimate of realized FDP compares favorably with Efron (2007)'s approach, as demonstrated in the sim...
Institute of Scientific and Technical Information of China (English)
WANG Shao-Kai; REN Ji-Gang; PENG Cheng-Zhi; JIANG Shuo; WANG Xiang-Bin
2007-01-01
We report a method to realize the arbitrary inverse unitary transformation imposed by a single-mode fibre on photon's polarization by the succession of two quarter-wave plates and a half-wave plate. The process of realization by polarization state vector. The method is meaningful in quantum communication experiment such as quantum teleportation, in which an unknown arbitrary quantum state should be kept to be unchanged in the case of using a single-mode fibre for time delay.
Exact solution of the one-dimensional Hubbard model with arbitrary boundary magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Li, Yuan-Yuan; Cao, Junpeng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Wen-Li [Institute of Modern Physics, Northwest University, Xian 710069 (China); Beijing Center for Mathematics and Information Interdisciplinary Sciences, Beijing, 100048 (China); Shi, Kangjie [Institute of Modern Physics, Northwest University, Xian 710069 (China); Wang, Yupeng, E-mail: yupeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2014-02-15
The one-dimensional Hubbard model with arbitrary boundary magnetic fields is solved exactly via the Bethe ansatz methods. With the coordinate Bethe ansatz in the charge sector, the second eigenvalue problem associated with the spin sector is constructed. It is shown that the second eigenvalue problem can be transformed into that of the inhomogeneous XXX spin chain with arbitrary boundary fields which can be solved via the off-diagonal Bethe ansatz method.
Isotope specific arbitrary material sorter
Energy Technology Data Exchange (ETDEWEB)
Barty, Christopher P.J.
2015-12-08
A laser-based mono-energetic gamma-ray source is used to provide a rapid and unique, isotope specific method for sorting materials. The objects to be sorted are passed on a conveyor in front of a MEGa-ray beam which has been tuned to the nuclear resonance fluorescence transition of the desired material. As the material containing the desired isotope traverses the beam, a reduction in the transmitted MEGa-ray beam occurs. Alternately, the laser-based mono-energetic gamma-ray source is used to provide non-destructive and non-intrusive, quantitative determination of the absolute amount of a specific isotope contained within pipe as part of a moving fluid or quasi-fluid material stream.
Transverse vibrations of arbitrary non-uniform beams
Institute of Scientific and Technical Information of China (English)
郭树起; 杨绍普
2014-01-01
Free and steady state forced transverse vibrations of non-uniform beams are investigated with a proposed method, leading to a series solution. The obtained series is verified to be convergent and linearly independent in a convergence test and by the non-zero value of the corresponding Wronski determinant, respectively. The obtained solution is rigorous, which can be reduced to a classical solution for uniform beams. The proposed method can deal with arbitrary non-uniform Euler-Bernoulli beams in principle, but the methods in terms of special functions or elementary functions can only work in some special cases.
Trivariate Local Lagrange Interpolation and Macro Elements of Arbitrary Smoothness
Matt, Michael Andreas
2012-01-01
Michael A. Matt constructs two trivariate local Lagrange interpolation methods which yield optimal approximation order and Cr macro-elements based on the Alfeld and the Worsey-Farin split of a tetrahedral partition. The first interpolation method is based on cubic C1 splines over type-4 cube partitions, for which numerical tests are given. The second is the first trivariate Lagrange interpolation method using C2 splines. It is based on arbitrary tetrahedral partitions using splines of degree nine. The author constructs trivariate macro-elements based on the Alfeld split, where each tetrahedron
Automatic Shape Control of Triangular B-Splines of Arbitrary Topology
Institute of Scientific and Technical Information of China (English)
Ying He; Xian-Feng Gu; Hong Qin
2006-01-01
Triangular B-splines are powerful and flexible in modeling a broader class of geometric objects defined over arbitrary, non-rectangular domains. Despite their great potential and advantages in theory, practical techniques and computational tools with triangular B-splines are less-developed. This is mainly because users have to handle a large number of irregularly distributed control points over arbitrary triangulation. In this paper, an automatic and efficient method is proposed to generate visually pleasing, high-quality triangular B-splines of arbitrary topology. The experimental results on several real datasets show that triangular B-splines are powerful and effective in both theory and practice.
Vacuum Birefringence Caused by Arbitrary Spin Particles
Kruglov, S. I.
2007-01-01
We study the propagation of a linearly polarized laser beam in the external transverse magnetic field taking into consideration the vacuum polarization by arbitrary spin particles. Induced ellipticity of the beam are evaluated using the effective Lagrangian. With the help of the PVLAS experimental data, we obtain bounds on masses of charged higher spin particles contributed to ellipticity.
Kraus representation for arbitrary open qubit system
Tong, D M; Kwek, L C; Oh, C H; Chen, Jing-Ling
2003-01-01
We show that the time evolution of an arbitrary open qubit system can always be described in terms of the Kraus representation irrespective of the presence of initial correlations between the open system and its environment. A general scheme on how to construct the Kraus operators for an open qubit system is proposed, which can be generalized to open higher dimensional quantum systems.
Self-forces on static bodies in arbitrary dimensions
Harte, Abraham I.; Flanagan, Éanna É.; Taylor, Peter
2016-06-01
We derive exact expressions for the scalar and electromagnetic self-forces and self-torques acting on arbitrary static extended bodies in arbitrary static spacetimes with any number of dimensions. Nonperturbatively, our results are identical in all dimensions. Meaningful point particle limits are quite different in different dimensions, however. These limits are defined and evaluated, resulting in simple "regularization algorithms" which can be used in concrete calculations. In these limits, self-interaction is shown to be progressively less important in higher numbers of dimensions; it generically competes in magnitude with increasingly high-order extended-body effects. Conversely, we show that self-interaction effects can be relatively large in 1 +1 and 2 +1 dimensions. Our motivations for this work are twofold: First, no previous derivation of the self-force has been provided in arbitrary dimensions, and heuristic arguments presented by different authors have resulted in conflicting conclusions. Second, the static self-force problem in arbitrary dimensions provides a valuable test bed with which to continue the development of general, nonperturbative methods in the theory of motion. Several new insights are obtained in this direction, including a significantly improved understanding of the renormalization process. We also show that there is considerable freedom to use different "effective fields" in the laws of motion—a freedom which can be exploited to optimally simplify specific problems. Different choices give rise to different inertias, gravitational forces, and electromagnetic or scalar self-forces, but there is a sense in which none of these quantities are individually accessible to experiment. Certain combinations are observable, however, and these remain invariant under all possible field redefinitions.
Arbitrary Phase Vocoders by means of Warping
Directory of Open Access Journals (Sweden)
Gianpaolo Evangelista
2013-08-01
Full Text Available The Phase Vocoder plays a central role in sound analysis and synthesis, allowing us to represent a sound signal in both time and frequency, similar to a music score – but possibly at much finer time and frequency scales – describing the evolution of sound events. According to the uncertainty principle, time and frequency are not independent variables so that any time-frequency representation is the result of a compromise between time and frequency resolutions, the product of which cannot be smaller than a given constant. Therefore, finer frequency resolution can only be achieved with coarser time resolution and, similarly, finer time resolution results in coarser frequency resolution.While most of the conventional methods for time-frequency representations are based on uniform time and uniform frequency resolutions, perception and physical characteristics of sound signals suggest the need for nonuniform analysis and synthesis. As the results of psycho-acoustic research show, human hearing is naturally organized in nonuniform frequency bands. On the physical side, the sounds of percussive instruments as well as piano in the low register, show partials whose frequencies are not uniformly spaced, as opposed to the uniformly spaced partial frequencies found in harmonic sounds. Moreover, the different characteristics of sound signals at the onset transients with respect to stationary segments suggest the need for nonuniform time resolution. In the effort to exploit the time-frequency resolution compromise at its best, a tight time-frequency suit should be tailored to snuggly fit the sound body.In this paper we overview flexible design methods for phase vocoders with nonuniform resolutions. The methods are based on remapping the time or the frequency axis, or both, by employing suitable functions acting as warping maps, which locally change the characteristics of the time-frequency plane. As a result, the sliding windows may have time dependent
Two-body quantum propagation in arbitrary potentials
Grasselli, Federico; Bertoni, Andrea; Goldoni, Guido
2016-08-01
We have implemented a unitary, numerically exact, Fourier split step method, based on a proper Suzuki-Trotter factorization of the quantum evolution operator, to propagate a two-body complex in arbitrary external potential landscapes taking into account exactly the internal structure. We have simulated spatially indirect Wannier-Mott excitons - optically excited electron-hole pairs with the two charges confined to different layers of a semiconductor heterostructure with prototypical 1D and 2D potentials emphasizing the effects of the internal dynamics and the insufficiency of mean-field methods in this context.
Pose Estimation from a Single Depth Image for Arbitrary Kinematic Skeletons
Ly, Daniel L; Lipson, Hod
2011-01-01
We present a method for estimating pose information from a single depth image given an arbitrary kinematic structure without prior training. For an arbitrary skeleton and depth image, an evolutionary algorithm is used to find the optimal kinematic configuration to explain the observed image. Results show that our approach can correctly estimate poses of 39 and 78 degree-of-freedom models from a single depth image, even in cases of significant self-occlusion.
Quantum Fidelity for Arbitrary Gaussian States
Banchi, Leonardo; Braunstein, Samuel L.; Pirandola, Stefano
2015-12-01
We derive a computable analytical formula for the quantum fidelity between two arbitrary multimode Gaussian states which is simply expressed in terms of their first- and second-order statistical moments. We also show how such a formula can be written in terms of symplectic invariants and used to derive closed forms for a variety of basic quantities and tools, such as the Bures metric, the quantum Fisher information, and various fidelity-based bounds. Our result can be used to extend the study of continuous-variable protocols, such as quantum teleportation and cloning, beyond the current one-mode or two-mode analyses, and paves the way to solve general problems in quantum metrology and quantum hypothesis testing with arbitrary multimode Gaussian resources.
Quantum fidelity for arbitrary Gaussian states
Banchi, Leonardo; Pirandola, Stefano
2015-01-01
We derive a computable analytical formula for the quantum fidelity between two arbitrary multimode Gaussian states which is simply expressed in terms of their first- and second-order statistical moments. We also show how such a formula can be written in terms of symplectic invariants and used to derive closed forms for a variety of basic quantities and tools, such as the Bures metric, the quantum Fisher information and various fidelity-based bounds. Our result can be used to extend the study of continuous-variable protocols, such as quantum teleportation and cloning, beyond the current one-mode or two-mode analyses, and paves the way to solve general problems in quantum metrology and quantum hypothesis testing with arbitrary multimode Gaussian resources.
Arbitrary orbital angular momentum of photons
Pan, Yue; Gao, Xu-Zhen; Ren, Zhi-Cheng; Wang, Xi-Lin; Tu, Chenghou; Li, Yongnan; Wang, Hui-Tian
2015-01-01
Orbital angular momentum (OAM) of photons, as a new fundamental degree of freedom, has excited a great diversity of interest, because of a variety of emerging applications. Arbitrarily tunable OAM has gained much attention, but its creation remains still a tremendous challenge. We demonstrate the realization of well-controlled arbitrary OAM in both theory and experiment. We present the concept of general OAM, which extends the OAM carried by the scalar vortex field to the OAM carried by the a...
A collection of 13 transposon mutants deficient in pyoverdine production was analyzed using an arbitrary polymerase chain reaction (PCR) approach to map the sites of Tn5 insertions in the genome of Pseudomonas fluorescens Pf-5. The arbitrary PCR method involved two rounds of reactions, with the fi...
Phase Matching of SHG in Arbitrary Directions of Biaxial Crystals
Institute of Scientific and Technical Information of China (English)
YANG Shengli; CHEN Mouzhi
2002-01-01
In this paper, propagation and polarization characteristics of optical waves in arbitrary directions in a biaxial crystal are analyzed, and universal relationships of refractive index dependence on their propagation directions and the principal refractive indices for two perpendicular polarization waves propagating in arbitrarily directions are derived from indicatrix equation. By using these relationships, methods of collinear phase matching (PM) of SHG are developed, and general expressions of the collinear PM angle dependent of the principal indices are given for SHG in arbitrarily directions. The expressions may be used to make optimization design of PM by computer for the SHG and to select optimum PM direction and to raise the SHG conversion efficiencies.
Statistical Reconstruction of arbitrary spin states of particles: root approach
Bogdanov, Y I
2005-01-01
A method of quantum tomography of arbitrary spin particle states is developed on the basis of the root approach. It is shown that the set of mutually complementary distributions of angular momentum projections can be naturally described by a set of basis functions based on the Kravchuk polynomials. The set of Kravchuk basis functions leads to a multi-parametric statistical distribution that generalizes the binomial distribution. In order to analyze a statistical inverse problem of quantum mechanics, we investigated the likelihood equation and the statistical properties of the obtained estimates. The conclusions of the analytical researches are approved by the results of numerical calculations.
Quantum tomography of arbitrary spin states of particles: root approach
Bogdanov, Yu. I.
2006-05-01
A method of quantum tomography of arbitrary spin particle states is developed on the basis of the root approach. It is shown that the set of mutually complementary distributions of angular momentum projections can be naturally described by a set of basis functions based on the Kravchuk polynomials. The set of Kravchuk basis functions leads to a multiparametric statistical distribution that generalizes the binomial distribution. In order to analyze a statistical inverse problem of quantum mechanics, we investigated the likelihood equation and the statistical properties of the obtained estimates. The conclusions of the analytical researches are approved by the results of numerical calculations.
Duality for massive spin two theories in arbitrary dimensions
Gonzalez, B; Khoudeir, A.; Montemayor, R.; Urrutia, L. F.
2008-01-01
Using the parent Lagrangian approach we construct a dual formulation, in the sense originally proposed by Curtright and Freund, of a massive spin two Fierz-Pauli theory in arbitrary dimensions $D$. This is achieved in terms of a mixed symmetry tensor $T_{A[B_{1}B_{2}... B_{D-2}]}$, without the need of auxiliary fields. The relation of this method with an alternative formulation based on a gauge symmetry principle proposed by Zinoviev is elucidated. We show that the latter formulation in four ...
Minimum-Energy Bivariate Wavelet Frame with Arbitrary Dilation Matrix
Directory of Open Access Journals (Sweden)
Fengjuan Zhu
2013-01-01
Full Text Available In order to characterize the bivariate signals, minimum-energy bivariate wavelet frames with arbitrary dilation matrix are studied, which are based on superiority of the minimum-energy frame and the significant properties of bivariate wavelet. Firstly, the concept of minimum-energy bivariate wavelet frame is defined, and its equivalent characterizations and a necessary condition are presented. Secondly, based on polyphase form of symbol functions of scaling function and wavelet function, two sufficient conditions and an explicit constructed method are given. Finally, the decomposition algorithm, reconstruction algorithm, and numerical examples are designed.
NEW DESIGN OF ROBUST OPTIMAL ARBITRARY TIME-DELAY FILTER
Institute of Scientific and Technical Information of China (English)
WANG Xiaojun; SHAO Huihe
2007-01-01
Zero placement method in the frequency domain is utilized to design robust multi-hump EI optimal arbitrary time-delay filter (OATF) by placing two or more filter zeros near the system poles. A total insensitive OATF can be also achieved if the problem of insensitivity to damping errors is considered. This design strategy is easier to derive and implement. Applications in the anti-swing control of overhead cranes verify the fine performance of this strategy. A better suppression of the load vibrations is obtained using the proposed new OATF, which is more robust to the variation of the cable length.
Arbitrary precision composite pulses for NMR quantum computing.
Alway, William G; Jones, Jonathan A
2007-11-01
We discuss the implementation of arbitrary precision composite pulses developed using the methods of Brown et al. [K.R. Brown, A.W. Harrow, I.L. Chuang, Arbitrarily accurate composite pulse sequences, Phys. Rev. A 70 (2004) 052318]. We give explicit results for pulse sequences designed to tackle both the simple case of pulse length errors and the more complex case of off-resonance errors. The results are developed in the context of NMR quantum computation, but could be applied more widely.
Arbitrary Finite-time Tracking Control for Magnetic Levitation Systems
Directory of Open Access Journals (Sweden)
Xuan-Toa Tran
2014-10-01
Full Text Available In this paper, an arbitrary finite-time tracking control (AFTC method is developed for magnetic levitation systems with uncertain dynamics and external disturbances. By introducing a novel augmented sliding- mode manifold function, the proposed method can eliminate the singular problem in traditional terminal sliding-mode control, as well as the reaching-phase problem. Moreover, the tracking errors can reach the reference value with faster convergence and better tracking precision in arbitrarily determined finite time. In addition, a fuzzy-arbitrary finite-time tracking control (F- AFTC scheme that combines a fuzzy technique with AFTC to enhance the robustness and sliding performance is also proposed. A fuzzy logic system is used to replace the discontinuous control term. Thus, the chattering phenomenon is resolved without degrading the tracking performance. The stability of the closed-loop system is guaranteed by the Lyapunov theory. Finally, the effectiveness of the proposed methods is illustrated by simulation and experimental study in a real magnetic levitation system.
Circuits with arbitrary gates for random operators
Jukna, S.; Schnitger, G.
2010-01-01
We consider boolean circuits computing n-operators f:{0,1}^n --> {0,1}^n. As gates we allow arbitrary boolean functions; neither fanin nor fanout of gates is restricted. An operator is linear if it computes n linear forms, that is, computes a matrix-vector product y=Ax over GF(2). We prove the existence of n-operators requiring about n^2 wires in any circuit, and linear n-operators requiring about n^2/\\log n wires in depth-2 circuits, if either all output gates or all gates on the middle laye...
*-Regular Leavitt Path Algebras of Arbitrary Graphs
Institute of Scientific and Technical Information of China (English)
Gonzalo ARANDA PINO; Kulumani RANGASWAMY; Lia VA(S)
2012-01-01
If K is a field with involution and E an arbitrary graph,the involution from K naturally induces an involution of the Leavitt path algebra LK(E).We show that the involution on LK(E) is proper if the involution on K is positive-definite,even in the case when the graph E is not necessarily finite or row-finite.It has been shown that the Leavitt path algebra LK(E) is regular if and only if E is acyclic.We give necessary and sufficient conditions for LK(E) to be *-regular (i.e.,regular with proper involution).This characterization of *-regularity of a Leavitt path algebra is given in terms of an algebraic property of K,not just a graph-theoretic property of E.This differs from the.known characterizations of various other algebraic properties of a Leavitt path algebra in terms of graphtheoretic properties of E alone.As a corollary,we show that Handelman's conjecture (stating that every *-regular ring is unit-regular) holds for Leavitt path algebras.Moreover,its generalized version for rings with local units also continues to hold for Leavitt path algebras over arbitrary graphs.
Double layers and double wells in arbitrary degenerate plasmas
Akbari-Moghanjoughi, M.
2016-06-01
Using the generalized hydrodynamic model, the possibility of variety of large amplitude nonlinear excitations is examined in electron-ion plasma with arbitrary electron degeneracy considering also the ion temperature effect. A new energy-density relation is proposed for plasmas with arbitrary electron degeneracy which reduces to the classical Boltzmann and quantum Thomas-Fermi counterparts in the extreme limits. The pseudopotential method is employed to find the criteria for existence of nonlinear structures such as solitons, periodic nonlinear structures, and double-layers for different cases of adiabatic and isothermal ion fluids for a whole range of normalized electron chemical potential, η0, ranging from dilute classical to completely degenerate electron fluids. It is observed that there is a Mach-speed gap in which no large amplitude localized or periodic nonlinear excitations can propagate in the plasma under consideration. It is further revealed that the plasma under investigation supports propagation of double-wells and double-layers the chemical potential and Mach number ranges of which are studied in terms of other plasma parameters. The Mach number criteria for nonlinear waves are shown to significantly differ for cases of classical with η0 0 regimes. It is also shown that the localized structure propagation criteria possess significant dissimilarities for plasmas with adiabatic and isothermal ions. Current research may be generalized to study the nonlinear structures in plasma containing positrons, multiple ions with different charge states, and charged dust grains.
Spectroscopy of the Schwarzschild black hole at arbitrary frequencies.
Casals, Marc; Ottewill, Adrian
2012-09-14
Linear field perturbations of a black hole are described by the Green function of the wave equation that they obey. After Fourier decomposing the Green function, its two natural contributions are given by poles (quasinormal modes) and a largely unexplored branch cut in the complex frequency plane. We present new analytic methods for calculating the branch cut on a Schwarzschild black hole for arbitrary values of the frequency. The branch cut yields a power-law tail decay for late times in the response of a black hole to an initial perturbation. We determine explicitly the first three orders in the power-law and show that the branch cut also yields a new logarithmic behavior T(-2ℓ-5)lnT for late times. Before the tail sets in, the quasinormal modes dominate the black hole response. For electromagnetic perturbations, the quasinormal mode frequencies approach the branch cut at large overtone index n. We determine these frequencies up to n(-5/2) and, formally, to arbitrary order. Highly damped quasinormal modes are of particular interest in that they have been linked to quantum properties of black holes.
Efficient scheme for parametric fitting of data in arbitrary dimensions.
Pang, Ning-Ning; Tzeng, Wen-Jer; Kao, Hisen-Ching
2008-07-01
We propose an efficient scheme for parametric fitting expressed in terms of the Legendre polynomials. For continuous systems, our scheme is exact and the derived explicit expression is very helpful for further analytical studies. For discrete systems, our scheme is almost as accurate as the method of singular value decomposition. Through a few numerical examples, we show that our algorithm costs much less CPU time and memory space than the method of singular value decomposition. Thus, our algorithm is very suitable for a large amount of data fitting. In addition, the proposed scheme can also be used to extract the global structure of fluctuating systems. We then derive the exact relation between the correlation function and the detrended variance function of fluctuating systems in arbitrary dimensions and give a general scaling analysis.
ABJM Wilson loops in arbitrary representations
Energy Technology Data Exchange (ETDEWEB)
Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Honda, Masazumi [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst. and Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics
2013-06-15
We study vacuum expectation values (VEVs) of circular half BPS Wilson loops in arbitrary representations in ABJM theory. We find that those in hook representations are reduced to elementary integrations thanks to the Fermi gas formalism, which are accessible from the numerical studies similar to the partition function in the previous studies. For non-hook representations, we show that the VEVs in the grand canonical formalism can be exactly expressed as determinants of those in the hook representations. Using these facts, we can study the instanton effects of the VEVs in various representations. Our results are consistent with the worldsheet instanton effects studied from the topological string and a prescription to include the membrane instanton effects by shifting the chemical potential, which has been successful for the partition function.
Discrete Equilibrium Sampling with Arbitrary Nonequilibrium Processes
Hamze, Firas
2015-01-01
We present a novel framework for performing statistical sampling, expectation estimation, and partition function approximation using \\emph{arbitrary} heuristic stochastic processes defined over discrete state spaces. Using a highly parallel construction we call the \\emph{sequential constraining process}, we are able to simultaneously generate states with the heuristic process and accurately estimate their probabilities, even when they are far too small to be realistically inferred by direct counting. After showing that both theoretically correct importance sampling and Markov chain Monte Carlo are possible using the sequential constraining process, we integrate it into a methodology called \\emph{state space sampling}, extending the ideas of state space search from computer science to the sampling context. The methodology comprises a dynamic data structure that constructs a robust Bayesian model of the statistics generated by the heuristic process subject to an accuracy constraint, the posterior Kullback-Leibl...
Metamaterial Electromagnetic Superabsorber with Arbitrary Geometries
Directory of Open Access Journals (Sweden)
Jingjing Yang
2010-06-01
Full Text Available The electromagnetic superabsorber that has larger absorption cross section than its real size may be a novel photothermal device with improved solar energy conversion rates. Based on a transformation optical approach, the material parameters for a two-dimensional (2D metamaterial-assisted electromagnetic superabsorber with arbitrary geometries are derived and validated by numerical simulation. We find that for the given geometry size, the absorption cross section of the superabsorber using nonlinear transformation is larger than that using linear transformation. These transformations can also be specialized to the designing the N-sided regular polygonal superabsorber just by changing the contour equation. All theoretical and numerical results validate the material parameters for the 2D electromagnetic superabsorber we have developed.
An Arbitrary Benchmark CAPM: One Additional Frontier Portfolio is Sufficient
Ekern, Steinar
2008-01-01
The benchmark CAPM linearly relates the expected returns on an arbitrary asset, an arbitrary benchmark portfolio, and an arbitrary MV frontier portfolio. The benchmark is not required to be on the frontier and may be non-perfectly correlated with the frontier portfolio. The benchmark CAPM extends and generalizes previous CAPM formulations, including the zero beta, two correlated frontier portfolios, riskless augmented frontier, and inefficient portfolio versions. The covariance between the of...
采用DSP技术适用于任意色散媒质的FDTD方法研究%Frequency-Dependent FDTD Method Using DSP for Arbitrary Dispersive Media
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A new frequency dependent finite difference time domain (FD-FDTD) method using digital signal processing (DSP) is proposed.The dispersive media is characterized as an infinite-impulse response (IIR) filter, directly leading to FDTD equations. The representation of a dispersive medium is therefore converted to a problem of digital fIR design. It is shown that the numerical results are consistent with analytic solution.
Maric, Tomislav; Marschall, Holger; Bothe, Dieter
2013-01-01
A new parallelized unsplit geometrical Volume of Fluid (VoF) algorithm with support for arbitrary unstructured meshes and dynamic local Adaptive Mesh Refinement (AMR), as well as for two and three dimensional computation is developed. The geometrical VoF algorithm supports arbitrary unstructured meshes in order to enable computations involving flow domains of arbitrary geometrical complexity. The implementation of the method is done within the framework of the OpenFOAM library for Computation...
Gyrokinetic theory for arbitrary wavelength electromagnetic modes in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Qin, H.; Tang, W.M.; Rewoldt, G.
1997-10-15
A linear gyrokinetic system for arbitrary wavelength electromagnetic modes is developed. A wide range of modes in inhomogeneous plasmas, such as the internal kink modes, the toroidal Alfven eigenmode (TAE) modes, and the drift modes, can be recovered from this system. The inclusion of most of the interesting physical factors into a single framework enables one to look at many familiar modes simultaneously and thus to study the modifications of and the interactions between them in a systematic way. Especially, the authors are able to investigate self-consistently the kinetic MHD phenomena entirely from the kinetic side. Phase space Lagrangian Lie perturbation methods and a newly developed computer algebra package for vector analysis in general coordinate system are utilized in the analytical derivation. In tokamak geometries, a 2D finite element code has been developed and tested. In this paper, they present the basic theoretical formalism and some of the preliminary results.
Source point calibration from an arbitrary electron backscattering pattern
DEFF Research Database (Denmark)
Lassen, Niels Christian Krieger
1999-01-01
Precise knowledge of the position of the source point is a requirement if electron backscattering patterns (EBSPs) are to be used for crystal orientation measurements or other types of measurements which demand a geometrical analysis of the patterns. Today, possibly the most popular method...... for locating the source point is a computational technique which uses the positions of a number of indexed Kikuchi bands for calculating the coordinates of the point. A serious limitation of this calibration technique is, however, that the localized bands must first be indexed, which is difficult...... if the location of the source point is not known with reasonable precision. This paper describes a new technique which determines the location of the source point from the positions of a number of bands in an arbitrary EBSP. Besides the positions of the Kikuchi bands, the only information which is required...
Exact results for Wilson loops in arbitrary representations
International Nuclear Information System (INIS)
We compute the exact vacuum expectation value of 1/2 BPS circular Wilson loops of N=4 U(N) super Yang-Mills in arbitrary irreducible representations. By localization arguments, the computation reduces to evaluating certain integrals in a Gaussian matrix model, which we do using the method of orthogonal polynomials. Our results are particularly simple for Wilson loops in antisymmetric representations; in this case, we observe that the final answers admit an expansion where the coefficients are positive integers, and can be written in terms of sums over skew Young diagrams. As an application of our results, we use them to discuss the exact Bremsstrahlung functions associated to the corresponding heavy probes
Exact results for Wilson loops in arbitrary representations
Fiol, Bartomeu
2013-01-01
We compute the exact vacuum expectation value of 1/2 BPS circular Wilson loops of ${\\cal N}$=4 U(N) super Yang-Mills in arbitrary irreducible representations. By localization arguments, the computation reduces to evaluating certain integrals in a Gaussian matrix model, which we do using the method of orthogonal polynomials. Our results are particularly simple for Wilson loops in antisymmetric representations; in this case, we observe that the final answers admit an expansion where the coefficients are positive integers, and can be written in terms of sums over skew Young diagrams. As an application of our results, we use them to discuss the exact Bremsstrahlung functions associated to the corresponding heavy probes.
Computation of impinging droplet with soluble surfactants and dynamic contact angle
Ganesan, Sashikumaar
2014-01-01
An arbitrary Lagrangian--Eulerian (ALE) finite element scheme for computations of soluble surfactant droplet impingement on a horizontal surface is presented. The numerical scheme solves the time-dependent Navier--Stokes equations for the fluid flow, scalar convection-diffusion equation for the surfactant transport in the bulk phase, and simultaneously, surface evolution equations for the surfactants on the free surface and on the liquid-solid interface. The effects of surfactants on the flow...
Aeroelastic Coupling Between a Low Mach Inviscid Flow and a Flexible Generic Airship
El Omari, Kamal; Schall, Eric; Koobus, Bruno; Dervieux, Alain
2006-01-01
In the context of an airship development programme, inviscid flow behavior and its coupling with structure flexibility are investigated. For this purpose, we have chosen a nonlinear analysis tool relying on the unsteady Euler model for the flow part and the classical elastodynamic equations for the structure. The numerical model for the flow is based on a Mixed Element Volume discretization derived in an Arbitrary-Lagrangian-Eulerian framework in order to cope with the structural deformations...
Gurson's Model: ALE Formulation and Strain Localization
da Cunda, Luiz A. B.; Creus, Guillermo J.
2007-05-01
This paper presents a brief review of Gurson's damage model, employed to describes the strength degradation in ductile metals submitted to large plastic deformations. The damage model is applied using finite elements and an Arbitrary Lagrangian-Eulerian formulation (ALE), to ensure a better quality to the finite elements mesh. The study of the combined application of ALE and Gurson approach to damage modeling and strain localization is the object of this paper.
Research on Fractal-Scanning Path for Arbitrary Boundary Layer in Layered Manufacturing
Institute of Scientific and Technical Information of China (English)
阳佳; 宾鸿赞; 等
2002-01-01
The fractal curve is proposed as a novel scanning-path used in Layered Manufacturing.Aiming at a limitation that the fractal curve can only fill a square region,a method is developed to realize the trimming of fractal curve in arbitrary boundary layer by means of undging intersection points between parameterized arbitrary boundary and a FASS(space-filling,self-avoiding,simple and self-similar)fractal curve.Accordingly,the related algorithm concerning with determining intersection points has been investigated according to the recursion reature of the fractal curve,and in the process of the fractal curve traversed,the rule of udging intersection points is ascertained as well,so that the laser-scanning beam can “walk” along the fractal curve inside the desired boundary,and arbitrary contour components are fabricated.
Thermodynamic limit and surface energy of the XXZ spin chain with arbitrary boundary fields
Energy Technology Data Exchange (ETDEWEB)
Li, Yuan-Yuan [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Cao, Junpeng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Yang, Wen-Li [Institute of Modern Physics, Northwest University, Xian 710069 (China); Beijing Center for Mathematics and Information Interdisciplinary Sciences, Beijing 100048 (China); Shi, Kangjie [Institute of Modern Physics, Northwest University, Xian 710069 (China); Wang, Yupeng, E-mail: yupeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
2014-07-15
In two previous papers [26,27], the exact solutions of the spin-1/2 chains with arbitrary boundary fields were constructed via the off-diagonal Bethe ansatz (ODBA). Here we introduce a method to approach the thermodynamic limit of those models. The key point is that at a sequence of degenerate points of the crossing parameter η=η{sub m}, the off-diagonal Bethe ansatz equations (BAEs) can be reduced to the conventional ones. This allows us to extrapolate the formulae derived from the reduced BAEs to arbitrary η case with O(N{sup −2}) corrections in the thermodynamic limit N→∞. As an example, the surface energy of the XXZ spin chain model with arbitrary boundary magnetic fields is derived exactly. This approach can be generalized to all the ODBA solvable models.
GA BASED SYNTHESIS OF SATELLITE-BORNE MULTI-BEAM PLANAR ARRAY WITH ARBITRARY GEOMETRY
Institute of Scientific and Technical Information of China (English)
Jin Jun; Wang Huali; Zhu Wenming; Liu Yunzhi
2006-01-01
A planar array antenna with arbitrary geometry synthesis technique based on genetic algorithm is discussed. This approach avoids coding/decoding and directly works with complex numbers to simplify computing program and to speed up computation. This approach uses two crossover operators that can overcome premature convergence and the dependence of convergence on initial population. Simulation results show that this method is capable of synthesizing complex pattern shapes of planar arrays with arbitrary geometry and can realize good sidelobe suppression at the same time.
The characterization of a class of subspace pseudoframes with arbitrary real number translations
Energy Technology Data Exchange (ETDEWEB)
Chen Qingjiang [School of Science, Xi' an University of Architecture and Technology, Xi' an 710055 (China) and College of Mathematics and Information Science, Shaanxi Normal University, Xi' an 710062 (China)], E-mail: asdfgh84sxxa@126.com; Shi Zhi [School of Science, Xi' an University of Architecture and Technology, Xi' an 710055 (China); Cao Huaixin [College of Mathematics and Information Science, Shaanxi Normal University, Xi' an 710062 (China)
2009-12-15
In this article, the notion of generalized multiresolution structure is introduced. The concept of subspace pseudoframes with arbitrary real number translations is proposed. A new method for constructing a generalized multiresolution structure in Paley-Wiener subspace of L{sup 2}(R) is presented. A pyramid decomposition scheme is established based on such a generalized multiresolution structure. Finally, affine frames of space L{sup 2}(R) with arbitrary real number translations are obtained by virtue of the subspace pseudoframes and the pyramid decomposition scheme. Relation to some physical theories such as quarks confinement is also investigated.
SAMBA: Sparse Approximation of Moment-Based Arbitrary Polynomial Chaos
Ahlfeld, R.; Belkouchi, B.; Montomoli, F.
2016-09-01
A new arbitrary Polynomial Chaos (aPC) method is presented for moderately high-dimensional problems characterised by limited input data availability. The proposed methodology improves the algorithm of aPC and extends the method, that was previously only introduced as tensor product expansion, to moderately high-dimensional stochastic problems. The fundamental idea of aPC is to use the statistical moments of the input random variables to develop the polynomial chaos expansion. This approach provides the possibility to propagate continuous or discrete probability density functions and also histograms (data sets) as long as their moments exist, are finite and the determinant of the moment matrix is strictly positive. For cases with limited data availability, this approach avoids bias and fitting errors caused by wrong assumptions. In this work, an alternative way to calculate the aPC is suggested, which provides the optimal polynomials, Gaussian quadrature collocation points and weights from the moments using only a handful of matrix operations on the Hankel matrix of moments. It can therefore be implemented without requiring prior knowledge about statistical data analysis or a detailed understanding of the mathematics of polynomial chaos expansions. The extension to more input variables suggested in this work, is an anisotropic and adaptive version of Smolyak's algorithm that is solely based on the moments of the input probability distributions. It is referred to as SAMBA (PC), which is short for Sparse Approximation of Moment-Based Arbitrary Polynomial Chaos. It is illustrated that for moderately high-dimensional problems (up to 20 different input variables or histograms) SAMBA can significantly simplify the calculation of sparse Gaussian quadrature rules. SAMBA's efficiency for multivariate functions with regard to data availability is further demonstrated by analysing higher order convergence and accuracy for a set of nonlinear test functions with 2, 5 and 10
Institute of Scientific and Technical Information of China (English)
许飞; 谢海芬
2014-01-01
对单摆运动进行了讨论。通过对单摆进行能量分析，得出了单摆角频率与角度的关系式，然后运用微元法，推导出了单摆的理论周期公式。计算结果表明，所得到的单摆运动周期的理论公式与展开公式符合得很好。%The simple pendulum motion is discussed. The relation between angle frequency and angle of the pendulum is given through the energy analysis of the pendulum,and the theoretical period formula of simple pendulum is derived using the differential method. The calculation results show that the theoretical formula of the period of simple pendulum movement and Taylor expansion formula are in good agreement.
VECTORIAL COMPETENT VELOCITY FORMULATIONS ON ARBITRARY FACES FOR NON-UNIFORM SEDIMENTS
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
By considering concealing and revealing features of non-uniform sediments, and using analytical method of theoretical mechanics, vectorial competent bottom velocity formulations at arbitrary faces for both concealing and revealing sediments were given respectively. A series of relations similar to existed formulations were obtained by simplified the formulations.
Optimal Low-Thrust Limited-Power Transfers between Arbitrary Elliptic Coplanar Orbits
daSilvaFernandes, Sandro; dasChagasCarvalho, Francisco
2007-01-01
In this work, a complete first order analytical solution, which includes the short periodic terms, for the problem of optimal low-thrust limited-power transfers between arbitrary elliptic coplanar orbits in a Newtonian central gravity field is obtained through Hamilton-Jacobi theory and a perturbation method based on Lie series.
Maximum Likelihood Dynamic Factor Modeling for Arbitrary "N" and "T" Using SEM
Voelkle, Manuel C.; Oud, Johan H. L.; von Oertzen, Timo; Lindenberger, Ulman
2012-01-01
This article has 3 objectives that build on each other. First, we demonstrate how to obtain maximum likelihood estimates for dynamic factor models (the direct autoregressive factor score model) with arbitrary "T" and "N" by means of structural equation modeling (SEM) and compare the approach to existing methods. Second, we go beyond standard time…
The Prediction of the Work of Friction Force on the Arbitrary Path
Matehkolaee, Mehdi Jafari; Majidian, Kourosh
2013-01-01
In this paper we have calculated the work of friction force on the arbitrary path. In our method didn't use from energy conservative conceptions any way. The distinction of this procedure is that at least do decrease measurement on the path once. Thus we can forecast the amount of work of friction force without information about speed of…
Off-diagonal Bethe ansatz solution of the XXX spin-chain with arbitrary boundary conditions
Cao, Junpeng; Shi, Kangjie; Wang, Yupeng
2013-01-01
With the off-diagonal Bethe ansatz method proposed recently by the present authors, we exactly diagonalize the $XXX$ spin chain with arbitrary boundary fields. By constructing a functional relation between the eigenvalues of the transfer matrix and the quantum determinant, the associated $T-Q$ relation and the Bethe ansatz equations are derived.
Off-diagonal Bethe ansatz solution of the XXX spin chain with arbitrary boundary conditions
Cao, Junpeng; Yang, Wen-Li; Shi, Kangjie; Wang, Yupeng
2013-10-01
Employing the off-diagonal Bethe ansatz method proposed recently by the present authors, we exactly diagonalize the XXX spin chain with arbitrary boundary fields. By constructing a functional relation between the eigenvalues of the transfer matrix and the quantum determinant, the associated T-Q relation and the Bethe ansatz equations are derived.
On-chip generation of Einstein-Podolsky-Rosen states with arbitrary symmetry
Energy Technology Data Exchange (ETDEWEB)
Gräfe, Markus; Heilmann, René; Nolte, Stefan; Szameit, Alexander, E-mail: alexander.szameit@uni-jena.de [Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena (Germany)
2015-05-04
We experimentally demonstrate a method for integrated-optical generation of two-photon Einstein-Podolsky-Rosen states featuring arbitrary symmetries. In our setting, we employ detuned directional couplers to impose a freely tailorable phase between the two modes of the state. Our results allow to mimic the quantum random walk statistics of bosons, fermions, and anyons, particles with fractional exchange statistics.
Understanding rigid body motion in arbitrary dimensions
Leyvraz, Francois
2014-01-01
Why would anyone wish to generalize the already unappetizing subject of rigid body motion to an arbitrary number of dimensions? At first sight, the subject seems to be both repellent and superfluous. The author will try to argue that an approach involving no specifically three-dimensional constructs is actually easier to grasp than the traditional one and might thus be generally useful to understand rigid body motion both in three dimensions and in the general case. Specific differences between the viewpoint suggested here and the usual one include the following: here angular velocities are systematically treated as antisymmetric matrices, a symmetric tensor $I$ quite different from the moment of inertia tensor plays a central role, whereas the latter is shown to be a far more complex object, namely a tensor of rank four. A straightforward way to define it is given. The Euler equation is derived and the use of Noether's theorem to obtain conserved quantities is illustrated. Finally the equation of motion for ...
Competitive epidemic spreading over arbitrary multilayer networks
Darabi Sahneh, Faryad; Scoglio, Caterina
2014-06-01
This study extends the Susceptible-Infected-Susceptible (SIS) epidemic model for single-virus propagation over an arbitrary graph to an Susceptible-Infected by virus 1-Susceptible-Infected by virus 2-Susceptible (SI1SI2S) epidemic model of two exclusive, competitive viruses over a two-layer network with generic structure, where network layers represent the distinct transmission routes of the viruses. We find analytical expressions determining extinction, coexistence, and absolute dominance of the viruses after we introduce the concepts of survival threshold and absolute-dominance threshold. The main outcome of our analysis is the discovery and proof of a region for long-term coexistence of competitive viruses in nontrivial multilayer networks. We show coexistence is impossible if network layers are identical yet possible if network layers are distinct. Not only do we rigorously prove a region of coexistence, but we can quantitate it via interrelation of central nodes across the network layers. Little to no overlapping of the layers' central nodes is the key determinant of coexistence. For example, we show both analytically and numerically that positive correlation of network layers makes it difficult for a virus to survive, while in a network with negatively correlated layers, survival is easier, but total removal of the other virus is more difficult.
Including Arbitrary Antenna Patterns in Microwave Imaging of Buried Objects
DEFF Research Database (Denmark)
Meincke, Peter; Kim, Oleksiy S.; Lenler-Eriksen, Hans-Rudolph
2004-01-01
A linear inversion scheme for microwave imaging of buried objects is presented in which arbitrary antennas are accounted for through their plane-wave transmitting and receiving spectra......A linear inversion scheme for microwave imaging of buried objects is presented in which arbitrary antennas are accounted for through their plane-wave transmitting and receiving spectra...
Institute of Scientific and Technical Information of China (English)
胡鹏; 何钢; 徐佳炜; 刘瑞峰; 朱红
2016-01-01
为研究刚性机器人脚的形状对其在软土中沉陷特性的影响,以MAT147材料作为土壤本构模型,采用多物质ALE方法对刚性脚在土壤中的沉陷过程进行数值模拟.分别对刚性脚脚底有无孔洞对软土的应力分布和流动状态的影响进行了分析,结果表明,脚部在沉陷过程中,最大有效应力分布在脚底部边缘的正下方区域,刚性脚轮廓外围土壤的应力由大到小沿脚部轮廓向外发散.孔洞改变了脚部正下方土壤的应力分布,与无孔洞脚相比,带孔洞脚底正下方土壤应力在孔洞周围呈环形分布,深度方向上的应力分布相对均匀.孔洞还改变了土壤的流动状态,使得流向脚底部的土壤增多,密度增大,对脚部防陷有积极影响.对不同孔洞半径大小对刚性脚在软土中沉陷特性的影响也进行了比较,结果表明,相等底面积情况下,随着孔洞半径的增大,十字形凹陷处的应力也增大,脚底两倍圆孔半径范围内的应力分布越均匀,而对侧面土壤影响较小;孔洞半径影响了脚底土壤的流动状态,速度方向随着半径的增大由竖直向下变为竖直向上,土壤流速与孔的半径大小呈正相关,而同等压力情况下沉陷深度与孔洞半径大小呈负相关.%In order to analyze the influence of rigid foot's geometry shape of legged robot on the sinking process in soft soil, it uses MAT 147 material as the constitutive model of soil and realizes the dynamic simulation of rigid foot′s sinking process with Multi Material Arbitrary Lagrangian Eulerian ( MM-ALE) method.It obtains the influ-ence of holes at the bottom of rigid foot on the stress distributions and flow trend of soft soil.The results show that the maximum effective stress of soil concentrates at the bottom of the rigid foot near the edge and the effective stress divergs outwardly along the foot contour.Comparing to the foot with no holes, the holes at the bottom of foot change the stress
A 3D radiative transfer framework: X. Arbitrary Velocity Fields in the Co-moving Frame
Baron, E; Chen, Bin; Knop, Sebastian
2012-01-01
3-D astrophysical atmospheres will have random velocity fields. We seek to combine the methods we have developed for solving the 1-D problem with arbitrary flows to those that we have developed for solving the fully 3-D relativistic radiative transfer problem in the case of monotonic flows. The methods developed in the case of 3-D atmospheres with monotonic flows, solving the fully relativistic problem along curves defined by an affine parameter, are very flexible and can be extended to the case of arbitrary velocity fields in 3-D. Simultaneously, the techniques we developed for treating the 1-D problem with arbitrary velocity fields are easily adapted to the 3-D problem. The algorithm we present allows the solution of 3-D radiative transfer problems that include arbitrary wavelength couplings. We use a quasi-analytic formal solution of the radiative transfer equation that significantly improves the overall computation speed. We show that the approximate lambda operator developed in previous work gives good c...
Teleportation of an arbitrary mixture of diagonal states of multiqudit
International Nuclear Information System (INIS)
This paper proposes a scheme to teleport an arbitrary mixture of diagonal states of multiqutrit via classical correlation and classical communication. To teleport an arbitrary mixture of diagonal states of N qutrits, N classically correlated pairs of two qutrits are used as channel. The sender (Alice) makes Fourier transform and conditional gate (i.e., XOR(3) gate) on her qutrits and does measurement in appropriate computation bases. Then she sends N ctrits to the receiver (Bob). Based on the received information, Bob performs the corresponding unitary transformation on his qutrits and obtains the teleported state. Teleportation of an arbitrary mixture of diagonal states of multiqudit is also discussed
Teleportation of an arbitrary mixture of diagonal states of multiqudit
Institute of Scientific and Technical Information of China (English)
Du Qian-Hua; Lin Xiu-Min; Chen Zhi-Hua; Lin Gong-Wei; Chen Li-Bo; Gu Yong-Jian
2008-01-01
This paper proposes a scheme to teleport an arbitrary mixture of diagonal states of multiqutrit via classical correlation and classical communication. To teleport an arbitrary mixture of diagonal states of N qutrits, N classically correlated pairs of two qutrits are used as channel. The sender (Alice) makes Fourier transform and conditional gate (i.e., XOR(3) gate) on her qutrits and does measurement in appropriate computation bases. Then she sends N ctrits to the receiver (Bob). Based on the received information, Bob performs the corresponding unitary transformation on his qutrits and obtains the teleported state. Teleportation of an arbitrary mixture of diagonal states of multiqudit is also discussed.
Yang-Mills Instanton Sheaves with Arbitrary Topological Charges
Lai, Sheng-Hong; Lai, I-Hsun
2016-01-01
We use a set of ADHM 3-instanton data to systematically construct a class of SU(2) Yang-Mills instanton solutions with arbitrary topological charges. Moreover, by using the biquaternion calculation with biconjugation operation developed recently, these new ADHM data are used to construct a class of SL(2,C) Yang-Mills instanton sheaves on CP^3 with arbitrary topological charges k greater than 3. This result extends the previous construction of Yang-Mills 2-instanton sheaves to arbitrary higher k-instanton sheaves.
Feynman propagator for an arbitrary half-integral spin
Institute of Scientific and Technical Information of China (English)
黄时中; 张鹏飞; 阮图南; 祝玉灿; 郑志鹏
2003-01-01
Based on the solution to Bargmann-Wigner equation for a particle with arbitrary half-integral spin, a direct derivation of the projection operator and propagator for a particle with arbitrary half-integral spin is worked out. The projection operator constructed by Behrends and Fronsdal is re-deduced and confirmed and simplified, the general commutation rules and Feynman propagator with additional non-covariant terms for a free particle with arbitrary half-inteRzal spin are derived, and explicit expressions for the propagators for spins 3/2, 5/2 and 7/2 are provided.
Efficient Spectral Power Estimation on an Arbitrary Frequency Scale
Directory of Open Access Journals (Sweden)
F. Zaplata
2015-04-01
Full Text Available The Fast Fourier Transform is a very efficient algorithm for the Fourier spectrum estimation, but has the limitation of a linear frequency scale spectrum, which may not be suitable for every system. For example, audio and speech analysis needs a logarithmic frequency scale due to the characteristic of a human’s ear. The Fast Fourier Transform algorithms are not able to efficiently give the desired results and modified techniques have to be used in this case. In the following text a simple technique using the Goertzel algorithm allowing the evaluation of the power spectra on an arbitrary frequency scale will be introduced. Due to its simplicity the algorithm suffers from imperfections which will be discussed and partially solved in this paper. The implementation into real systems and the impact of quantization errors appeared to be critical and have to be dealt with in special cases. The simple method dealing with the quantization error will also be introduced. Finally, the proposed method will be compared to other methods based on its computational demands and its potential speed.
Modeling of amorphous carbon structures with arbitrary structural constraints.
Jornada, F H; Gava, V; Martinotto, A L; Cassol, L A; Perottoni, C A
2010-10-01
In this paper we describe a method to generate amorphous structures with arbitrary structural constraints. This method employs the simulated annealing algorithm to minimize a simple yet carefully tailored cost function (CF). The cost function is composed of two parts: a simple harmonic approximation for the energy-related terms and a cost that penalizes configurations that do not have atoms in the desired coordinations. Using this approach, we generated a set of amorphous carbon structures spawning nearly all the possible combinations of sp, sp(2) and sp(3) hybridizations. The bulk moduli of this set of amorphous carbons structures was calculated using Brenner's potential. The bulk modulus strongly depends on the mean coordination, following a power-law behavior with an exponent ν = 1.51 ± 0.17. A modified cost function that segregates carbon with different hybridizations is also presented, and another set of structures was generated. With this new set of amorphous materials, the correlation between the bulk modulus and the mean coordination weakens. The method proposed can be easily modified to explore the effects on the physical properties of the presence of hydrogen, dangling bonds, and structural features such as carbon rings.
A fast algorithm for simulating multiphase flows through periodic geometries of arbitrary shape
Marple, Gary; Gillman, Adrianna; Veerapaneni, Shravan
2015-01-01
This paper presents a new boundary integral equation (BIE) method for simulating particulate and multiphase flows through periodic channels of arbitrary smooth shape in two dimensions. The authors consider a particular system---multiple vesicles suspended in a periodic channel of arbitrary shape---to describe the numerical method and test its performance. Rather than relying on the periodic Green's function as classical BIE methods do, the method combines the free-space Green's function with a small auxiliary basis, and imposes periodicity as an extra linear condition. As a result, we can exploit existing free-space solver libraries, quadratures, and fast algorithms, and handle a large number of vesicles in a geometrically complex channel. Spectral accuracy in space is achieved using the periodic trapezoid rule and product quadratures, while a first-order semi-implicit scheme evolves particles by treating the vesicle-channel interactions explicitly. New constraint-correction formulas are introduced that prese...
Numerical computation of one-photon maser resonances for arbitrary field modes
Bastin, T
2000-01-01
We present a numerical method for computing the emission probability of an ultracold atom interacting with a high-Q cavity for an arbitrary field mode. The numerical method proposed replaces and improves advantageously the WKB approximation when considering actual interaction and cavity parameters. The cases of sinusoidal, sech^2 and gaussian field modes are studied and compared. Divergences with previous works, where WKB was used, are found.
Leading Chiral Logarithms for Pion Form Factors to Arbitrary Number of Loops
Kivel, N. A.; M. V. Polyakov; Vladimirov, A. A.
2009-01-01
We develop the method of calculation of the leading chiral (infrared) logarithms to an arbitrary loop order for various form factors of Nambu-Goldstone bosons. The method is illustrated on example of scalar and vector form factors in massless 4D O(N+1)/O(N) sigma-model. The analytical properties of the form factors are derived. The leading chiral (infrared) logarithms are summed up in the large N limit.
ON QUADRATURE FORMULAE FOR SINGULAR INTEGRALS OF ARBITRARY ORDER
Institute of Scientific and Technical Information of China (English)
杜金元
2004-01-01
Some quadrature formulae for the numerical evaluation of singular integrals of arbitrary order are established and both the estimate of remainder and the convergence of each quadrature formula derived here are also given.
Arbitrary orbital angular momentum addition in second harmonic generation
International Nuclear Information System (INIS)
We demonstrate second harmonic generation performed with optical vortices with different topological charges imprinted on orthogonal polarizations. Besides the intuitive charge doubling, we implement arbitrary topological charge addition on the second harmonic field using polarization as an auxiliary parameter. (paper)
Novel FBG Writing System With Arbitrary Amplitude and Phase Control
Institute of Scientific and Technical Information of China (English)
J.J.; Pan; Claire; Gu; Albert; Li; Henry; He
2003-01-01
FBGs with arbitrary apodization and phase have been fabricated by constantly moving fibers with a highly precision air bearing translation stage while a CW UV laser beam is switched on/off by triggers with nanosecond accuracy.
Sunrise: Polychromatic Dust Radiative Transfer in Arbitrary Geometries
Jonsson, Patrik
2006-01-01
This paper describes Sunrise, a parallel, free Monte-Carlo code for the calculation of radiation transfer through astronomical dust. Sunrise uses an adaptive-mesh refinement grid to describe arbitrary geometries of emitting and absorbing/scattering media, with spatial dynamical range exceeding 10^4, and it can efficiently generate images of the emerging radiation at arbitrary points in space. In addition to the monochromatic radiative transfer typically used by Monte-Carlo codes, Sunrise is c...
Closed description of arbitrariness in resolving quantum master equation
Batalin, Igor A.; Lavrov, Peter M.
2016-07-01
In the most general case of the Delta exact operator valued generators constructed of an arbitrary Fermion operator, we present a closed solution for the transformed master action in terms of the original master action in the closed form of the corresponding path integral. We show in detail how that path integral reduces to the known result in the case of being the Delta exact generators constructed of an arbitrary Fermion function.
Closed description of arbitrariness in resolving quantum master equation
Directory of Open Access Journals (Sweden)
Igor A. Batalin
2016-07-01
Full Text Available In the most general case of the Delta exact operator valued generators constructed of an arbitrary Fermion operator, we present a closed solution for the transformed master action in terms of the original master action in the closed form of the corresponding path integral. We show in detail how that path integral reduces to the known result in the case of being the Delta exact generators constructed of an arbitrary Fermion function.
Spread of arbitrary conventions among chimpanzees: a controlled experiment
Bonnie, Kristin E.; Horner, Victoria; Whiten, Andrew; de Waal, Frans B. M.
2006-01-01
Wild chimpanzees (Pan troglodytes) have a rich cultural repertoire—traditions common in some communities are not present in others. The majority of reports describe functional, material traditions, such as tool use. Arbitrary conventions have received far less attention. In the same way that observations of material culture in wild apes led to experiments to confirm social transmission and identify underlying learning mechanisms, experiments investigating how arbitrary habits or conventions a...
SOME SMALL DEVIATION THEOREMS FOR ARBITRARY CONTINUOUS RANDOM SEQUENCE
Institute of Scientific and Technical Information of China (English)
Wang Zhongzhi
2007-01-01
Let (Xn)n∈N be a sequence of arbitrary continuous random variables, by the notion of relative entropy h(μ)μ(ω) as a measure of dissimilarity between probability measure μ and reference measure (μ), the explicit, general bounds for the partial sums of arbitrary continuous random variables under suitable conditions are developed. The argument uses the known and elementary lemma of convergence for likelihood ratio.
CMOS circuits generating arbitrary chaos by using pulsewidthmodulation techniques
Morie, Takashi; Sakabayashi, S; Nagata, M.; Iwata, A
2000-01-01
This paper describes CMOS circuits generating arbitrary chaotic signals. The proposed circuits implement discrete-time continuous-state dynamics by means of analog processing in a time domain. Arbitrary nonlinear transformation functions can be generated by using the conversion from an analog voltage to a pulsewidth modulation (PWM) signal; for the transformation, time-domain nonlinear voltage waveforms having the same shape as the inverse function of the desired transformation function are u...
Ying, Leslie; Haldar, Justin; Liang, Zhi-Pei
2005-01-01
Parallel imaging using multiple receiver coils has emerged as an effective tool to reduce imaging time in various MRI applications. Although several different image reconstruction methods have been developed and demonstrated to be successful for Cartesian k-space trajectories, there is a lack of efficient reconstruction methods for arbitrary trajectories. In this paper, we formulate the reconstruction problem in k-space and propose a novel image reconstruction method that is fast and effective for arbitrary trajectories. To obtain the desired image, the method reconstructs the Nyquist-sampled k-space data of the image on a uniform Cartesian grid from the undersampled multichannel k-space data on an arbitrary grid, followed by inverse Fourier transform. We demonstrate the effectiveness of the proposed fast algorithm using simulations. In particular, we compare the proposed method with the existing iterative method and show that the former is able to achieve similar image quality to the latter but with reduced computational complexity. PMID:17282445
International Nuclear Information System (INIS)
In this paper, a novel method of getting the dispersion relations in planar grating with arbitrary grooves for terahertz Smith-Purcell radiation is investigated analytically. The continuous profile of the groove is approximately replaced by a series of rectangular steps. By making use of field matches method and the continuity of transverse admittance, the universal dispersion equation for grating with arbitrarily shaped grooves is derived. By solving the dispersion equation in presence of electron beam, the growth rate is obtained directly and the dependence on beam parameters is analyzed. Comparisons of the dispersion characteristics among some special groove shapes have been made by numerical calculation. The results show that the rectangular-step approximation method provides a novel approach to obtain the universal dispersion relation for grating with arbitrary grooves for Smith-Purcell radiation
Generation of Synthetic Turbulence in Arbitrary Domains
DEFF Research Database (Denmark)
Gilling, Lasse; Nielsen, Søren R.K.; Sørensen, Niels
2009-01-01
A new method for generating synthetic turbulence is presented. The method is intended for generating a turbulent velocity field with a fine spatial resolution but only covering a small moving part of the rotor area of a wind turbine. For this application the Mann and Sandia methods cannot be used...... because of the very high requirements for computer memory. In the present method the auto- and cross-correlation in all three directions is computed from analytical or empirical expressions and the auto- and cross-spectra are determined by using the Wiener-Khinchin relation. From the auto- and cross...
Efficient computation of spontaneous emission dynamics in arbitrary photonic structures
Teimourpour, M. H.; El-Ganainy, R.
2015-12-01
Defining a quantum mechanical wavefunction for photons is one of the remaining open problems in quantum physics. Thus quantum states of light are usually treated within the realm of second quantization. Consequently, spontaneous emission (SE) in arbitrary photonic media is often described by Fock space Hamiltonians. Here, we present a real space formulation of the SE process that can capture the physics of the problem accurately under different coupling conditions. Starting from first principles, we map the unitary evolution of a dressed two-level quantum emitter onto the problem of electromagnetic radiation from a self-interacting complex harmonic oscillator. Our formalism naturally leads to an efficient computational scheme of SE dynamics using finite difference time domain method without the need for calculating the photonic eigenmodes of the surrounding environment. In contrast to earlier investigations, our computational framework provides a unified numerical treatment for both weak and strong coupling regimes alike. We illustrate the versatility of our scheme by considering several different examples.
Efficient computation of spontaneous emission dynamics in arbitrary photonic structures
International Nuclear Information System (INIS)
Defining a quantum mechanical wavefunction for photons is one of the remaining open problems in quantum physics. Thus quantum states of light are usually treated within the realm of second quantization. Consequently, spontaneous emission (SE) in arbitrary photonic media is often described by Fock space Hamiltonians. Here, we present a real space formulation of the SE process that can capture the physics of the problem accurately under different coupling conditions. Starting from first principles, we map the unitary evolution of a dressed two-level quantum emitter onto the problem of electromagnetic radiation from a self-interacting complex harmonic oscillator. Our formalism naturally leads to an efficient computational scheme of SE dynamics using finite difference time domain method without the need for calculating the photonic eigenmodes of the surrounding environment. In contrast to earlier investigations, our computational framework provides a unified numerical treatment for both weak and strong coupling regimes alike. We illustrate the versatility of our scheme by considering several different examples. (paper)
All passive photonic power divider with arbitrary split ratio
Xu, Ke; Wen, Xiang; Sun, Wenzhao; Zhang, Nan; Yi, Ningbo; Sun, Shang; Xiao, Shumin; Song, Qinghai
2016-01-01
Integrated optical power splitter is one of the fundamental building blocks in photonic integrated circuits (PIC). Conventional multimode interferometer based power splitter is widely used as it has reasonable footprint and is easy to fabricate. However, it is challenging to realize arbitrary split ratio especially for multi-outputs. In this work, an ultra-compact power splitter with a QR code-like nanostructure is designed by a nonlinear fast search method (FSM). The highly functional structure is composed of a number of freely designed square pixels with the size of 120nm x 120nm which could be either dielectric or air. The lightwaves are scattered by a number of etched squares with optimized locations and the scattered waves superimpose at the outputs with the desired power ratio. We demonstrate 1x2 splitters with 1:1, 1:2, 1:3 split ratios and a 1x3 splitter with the ratio of 1:2:1. The footprint for all the devices is only 3.6umx3.6 um. Well-controlled split ratios are measured for all the cases. The mea...
Constructing reference metrics on multicube representations of arbitrary manifolds
Lindblom, Lee; Taylor, Nicholas W.; Rinne, Oliver
2016-05-01
Reference metrics are used to define the differential structure on multicube representations of manifolds, i.e., they provide a simple and practical way to define what it means globally for tensor fields and their derivatives to be continuous. This paper introduces a general procedure for constructing reference metrics automatically on multicube representations of manifolds with arbitrary topologies. The method is tested here by constructing reference metrics for compact, orientable two-dimensional manifolds with genera between zero and five. These metrics are shown to satisfy the Gauss-Bonnet identity numerically to the level of truncation error (which converges toward zero as the numerical resolution is increased). These reference metrics can be made smoother and more uniform by evolving them with Ricci flow. This smoothing procedure is tested on the two-dimensional reference metrics constructed here. These smoothing evolutions (using volume-normalized Ricci flow with DeTurck gauge fixing) are all shown to produce reference metrics with constant scalar curvatures (at the level of numerical truncation error).
Arbitrary axisymmetric steady streaming: Flow, force and propulsion
Spelman, Tamsin A
2015-01-01
A well-developed method to induce mixing on microscopic scales is to exploit flows generated by steady streaming. Steady streaming is a classical fluid dynamics phenomenon whereby a time-periodic forcing in the bulk or along a boundary is enhanced by inertia to induce a non-zero net flow. Building on classical work for simple geometrical forcing and motivated by the complex shape oscillations of elastic capsules and bubbles, we develop the mathematical framework to quantify the steady streaming of a spherical body with arbitrary axisymmetric time-periodic boundary conditions. We compute the flow asymptotically for small-amplitude oscillations of the boundary in the limit where the viscous penetration length scale is much smaller than the body. In that case, the flow has a boundary layer structure and the fluid motion is solved by asymptotic matching. Our results, presented in the case of no-slip boundary conditions and extended to include the motion of vibrating free surfaces, recovers classical work as parti...
International Nuclear Information System (INIS)
We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2-dimensional) or polyhedral (3-dimensional) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids. (authors)
International Nuclear Information System (INIS)
We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2D) or polyhedral (3D) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids
ONE-DIMENSIONAL CONSOLIDATION OF LAYERED AND VISCO-ELASTIC SOILS UNDER ARBITRARY LOADING
Institute of Scientific and Technical Information of China (English)
蔡袁强; 徐长节; 袁海明
2001-01-01
Based on the layered visco-elastic soil model, according to the Terzaghi' s one dimensional consolidation theory, by the method of Laplace transform and matrix transfer technique, the problems about the consolidation of layered and saturated visco-elastic soils under arbitrary loading were solved. Through deductions, the general solution, in the terms of layer thickness, the modulus and the coefficients of permeability and Laplacian transform' s parameters was obtained. The strain and deformation of the layered and satu rated visco-elastic soils under arbitrary loading can be calculated by Laplace inversion. Ac cording to the results of several numerical examples, the consolidation of visco-elastic soils lags behind that of elastic soils. The development of effective stress and the displacement is vibrant process under cyclic loading. Finally, an engineering case is studied and the results prove that the methods are very effective.
AVELLA-CASTIBLANCO, J; SEETHARAMDOO, D; BERBINEAU, M; NEY, M; GALLEE, F
2011-01-01
This paper presents the application of the modal theory for determining antenna positioning in the railway environment. An original technique based on the Transmission Line Matrix method (TLM) for the analysis of guided structures is used to model propagation in arbitrary-shaped tunnels. Wave propagation in a rectangular tunnel with lossy dielectric walls is then studied and optimum field specifications in terms of optimum electric or magnetic field and best position for exciting the structur...
Charlotte Y.F. Ho; Bingo W.K. Ling; Saverio G. Blasi; Zhi-Wei Chi; Wan-Chi Siu
2010-01-01
Problem statement: This study derives the optimal motion vector with arbitrary pixel precisions in a single step. Approach: A non-linear block matched motion model was proposed. Based on the proposed non-linear block matched motion model, the optimal motion vector which minimizes the mean square error was solved analytically in a single step via a gradient approach. Results: The mean square error based on the proposed method was guaranteed to be lower than or equal to that based on convention...
Atomic and field dynamics in the time-dependent Jaynes-Cummings model with arbitrary detuning
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
We propose a general numerical method for solving the time -dependent Jaynes-Cummings model with arbitrary detuning by integrating relate d groups of coupled equations using Runge-Kutta numerical technique. The atomic and field dynamics such as evolution of atomic population inversion and second -order correlation function of photons are studied in case of different detunin g. The results show that the field tends to exhibit bunching effect due to the I ncreasing of detuning.
Transfer of arbitrary quantum emitter states to near-field photon superpositions in nanocavities
Thijssen, Arthur C. T.; Martin J. Cryan; Rarity, John G.; Oulton, Ruth
2012-01-01
We present a method to analyze the suitability of particular photonic cavity designs for information exchange between arbitrary superposition states of a quantum emitter and the near-field photonic cavity mode. As an illustrative example, we consider whether quantum dot emitters embedded in "L3" and "H1" photonic crystal cavities are able to transfer a spin superposition state to a confined photonic superposition state for use in quantum information transfer. Using an established dyadic Green...
Bethe ansatz solution of the $\\tau_2$-model with arbitrary boundary fields
Xu, Xiaotian; Yang, Tao; Cao, Junpeng; Yang, Wen-Li; Shi, Kangjie
2016-01-01
The quantum $\\tau_2$-model with generic site-dependent inhomogeneity and arbitrary boundary fields is studied via the off-diagonal Bethe Ansatz method. The eigenvalues of the corresponding transfer matrix are given in terms of an inhomogeneous T-Q relation, which is based on the operator product identities among the fused transfer matrices and the asymptotic behavior of the transfer matrices. Moreover, the associated Bethe Ansatz equations are also obtained.
On the solutions of the $Z_n$-Belavin model with arbitrary number of sites
Hao, Kun; Li, Guang-Liang; Yang, Wen-Li; Shi, Kangjie; Wang, Yupeng
2016-01-01
The periodic $Z_n$-Belavin model on a lattice with an arbitrary number of sites $N$ is studied via the off-diagonal Bethe Ansatz method (ODBA). The eigenvalues of the corresponding transfer matrix are given in terms of an unified inhomogeneous $T-Q$ relation. In the special case of $N=nl$ with $l$ being also a positive integer, the resulting $T-Q$ relation recovers the homogeneous one previously obtained via algebraic Bethe Ansatz.
Status of CFDLIB performance tests on the T3D
Energy Technology Data Exchange (ETDEWEB)
Padial, N.T.; Kashiwa, B.A.; Kothe, D.B. [Los Alamos National Lab., NM (United States). Theoretical Div.
1994-11-01
CFDLIB is a collection of two- and three-dimensional computer codes for problems in computational fluid dynamics. The library handles a wide range of flow regimes both single and multiphase, from fully incompressible to hypersonic, chemically reacting or inert materials. The method uses the Implicity Continuous-fluid Eulerian scheme (ICE) which becomes essentially identical to the Marker and Cell (MAC) method in the incompressible limit. The method, a Finite-Volume scheme, with cell-centered state variables, utilizes an Arbitrary-Lagrangian-Eulerian (ALE) split computational cycle in the sense that the mesh is allowed to move in an arbitrary fashion. In addition, CFDLIB employs a multiblock data structure that proved extremely convenient for implementation on parallel computers. CFDLIB is now available in sequential or parallel environments, is written in standard FORTRAN 77, and is highly portable. Results are given for a selection of specialized applications that illustrate the kind of problems of interest to CFDLIB users. Finally, initial results are given for performance studies comparing the Cray Y-MP, T3D, and an IBM workstation cluster. For certain problems, a Y-MP-equivalent real solution time is achieved with less than eight processors on the T3D.
International Nuclear Information System (INIS)
SPLASH-ALE is a three-dimensional finite-element fluid-dynamics computer code employing Arbitrary Lagrangian Eulerian (ALE) method. Because the ALE method enables computational nodes to move in arbitrary velocity, this code can deal with moving boundaries such as free surface. In a reactor vessel of liquid metal cooled Fast Breeder Reactor (FBR), there is such situation that upward coolant flow impinges on its free surface and makes swell of the surface. In a experiment of simplified flow geometry of such situation, an upward plane jet impinging on free surface oscillates without any external force. In this study, the oscillation was numerically analyzed by the SPLASH-ALE code. The numerical results corresponded well with experimental those, e.g., streakline of the oscillating jet. It was confirmed that the SPLASH-ALE code is capable to analyze unstable phenomena caused by interaction between flow and free surface, and the numerical result is available to solve the mechanism of the oscillation. (author)
Time-Discrete Higher-Order ALE Formulations: Stability
Bonito, Andrea
2013-01-01
Arbitrary Lagrangian Eulerian (ALE) formulations deal with PDEs on deformable domains upon extending the domain velocity from the boundary into the bulk with the purpose of keeping mesh regularity. This arbitrary extension has no effect on the stability of the PDE but may influence that of a discrete scheme. We examine this critical issue for higher-order time stepping without space discretization. We propose time-discrete discontinuous Galerkin (dG) numerical schemes of any order for a time-dependent advection-diffusion-model problem in moving domains, and study their stability properties. The analysis hinges on the validity of the Reynold\\'s identity for dG. Exploiting the variational structure and assuming exact integration, we prove that our conservative and nonconservative dG schemes are equivalent and unconditionally stable. The same results remain true for piecewise polynomial ALE maps of any degree and suitable quadrature that guarantees the validity of the Reynold\\'s identity. This approach generalizes the so-called geometric conservation law to higher-order methods. We also prove that simpler Runge-Kutta-Radau methods of any order are conditionally stable, that is, subject to a mild ALE constraint on the time steps. Numerical experiments corroborate and complement our theoretical results. © 2013 Society for Industrial and Applied Mathematics.
Self-forces on static bodies in arbitrary dimensions
Harte, Abraham I; Taylor, Peter
2016-01-01
We derive exact expressions for the scalar and electromagnetic self-forces and self-torques acting on arbitrary static extended bodies in arbitrary static spacetimes with any number of dimensions. Non-perturbatively, our results are identical in all dimensions. Meaningful point particle limits are quite different in different dimensions, however. These limits are defined and evaluated, resulting in simple "regularization algorithms" which can be used in concrete calculations. In these limits, self-interaction is shown to be progressively less important in higher numbers of dimensions; it generically competes in magnitude with increasingly high-order extended-body effects. Conversely, we show that self-interaction effects can be relatively large in $1+1$ and $2+1$ dimensions. Our motivations for this work are twofold: First, no previous derivation of the self-force has been provided in arbitrary dimensions, and heuristic arguments presented by different authors have resulted in conflicting conclusions. Second,...
Bisimulation on Markov Processes over Arbitrary Measurable Spaces
DEFF Research Database (Denmark)
Bacci, Giorgio; Bacci, Giovanni; Larsen, Kim Guldstrand;
2014-01-01
We introduce a notion of bisimulation on labelled Markov Processes over generic measurable spaces in terms of arbitrary binary relations. Our notion of bisimulation is proven to coincide with the coalgebraic definition of Aczel and Mendler in terms of the Giry functor, which associates with a mea......We introduce a notion of bisimulation on labelled Markov Processes over generic measurable spaces in terms of arbitrary binary relations. Our notion of bisimulation is proven to coincide with the coalgebraic definition of Aczel and Mendler in terms of the Giry functor, which associates...
Topological flat band models with arbitrary Chern numbers
Yang, Shuo; Gu, Zheng-Cheng; Sun, Kai; Sarma, S. Das
2012-01-01
We report the theoretical discovery of a systematic scheme to produce topological flat bands (TFBs) with arbitrary Chern numbers. We find that generically a multi-orbital high Chern number TFB model can be constructed by considering multi-layer Chern number C=1 TFB models with enhanced translational symmetry. A series of models are presented as examples, including a two-band model on a triangular lattice with a Chern number C=3 and an $N$-band square lattice model with $C=N$ for an arbitrary ...
Probabilistic teleportation of an arbitrary three-particle state
Institute of Scientific and Technical Information of China (English)
Lin Xiu; Li Hong-Cai
2005-01-01
A scheme for teleporting an arbitrary and unknown three-particle state from a sender to either one of two receivers is proposed. The quantum channel is composed of a two-particle non-maximally entangled state and two three-particle non-maximally entangled W states. An arbitrary three-particle state can be perfectly teleported probabilistically if the sender performs three generalized Bell-state measurements and sends to the two receivers the classical result of these measurements, and either one of the two receivers adopts an appropriate unitary transformation conditioned on the suitable measurement outcomes of the other receiver. All kinds of unitary transformations are given in detail.
Probabilistic teleportation of an arbitrary pure state of two atoms
Institute of Scientific and Technical Information of China (English)
Yang Zhen-Biao; Wu Huai-Zhi; Su Wan-Jun
2007-01-01
In the context of microwave cavity QED, this paper proposes a new scheme for teleportation of an arbitrary pure state of two atoms. The scheme is very different from the previous ones which achieve the integrated state measurement,it deals in a probabilistic but simplified way. In the scheme, no additional atoms are involved and thus only two atoms are required to be detected. The scheme can also be used for the teleportation of arbitrary pure states of many atoms or two-mode cavities.
Feynman propagator for an arbitrary half-integral spin
Institute of Scientific and Technical Information of China (English)
黄时中; 张鹏飞; 阮图南; 祝玉灿; 郑志鹏
2003-01-01
Based on the solution to Bargmann-Wigner equation for a particle with arbitrary half-integral spin, a directderivation of the projection operator and propagator for a particle with arbitrary half-integral spin is worked out. Theprojection operator constructed by Behrends and Fronsdal is re-deduced and confirmed and simplified, the generalcommutation rules and Feynman propagator with additional non-covariant terms for a free particle with arbitraryhalf-integral spin are derived, and explicit expressions for the propagators for spins 3/2, 5/2 and 7/2 are provided.
Multi-scale graphene patterns on arbitrary substrates via laser-assisted transfer-printing process
Park, J. B.
2012-01-01
A laser-assisted transfer-printing process is developed for multi-scale graphene patterns on arbitrary substrates using femtosecond laser scanning on a graphene/metal substrate and transfer techniques without using multi-step patterning processes. The short pulse nature of a femtosecond laser on a graphene/copper sheet enables fabrication of high-resolution graphene patterns. Thanks to the scale up, fast, direct writing, multi-scale with high resolution, and reliable process characteristics, it can be an alternative pathway to the multi-step photolithography methods for printing arbitrary graphene patterns on desired substrates. We also demonstrate transparent strain devices without expensive photomasks and multi-step patterning process. © 2012 American Institute of Physics.
Quantum Information Splitting of Arbitrary Three-Qubit State by Using Seven-Qubit Entangled State
Li, Dong-fen; Wang, Rui-jin; Zhang, Feng-li; Deng, Fu-hu
2015-06-01
In this paper, we propose a scheme of quantum information splitting arbitrary three-qubit state by using seven-qubit entangled as quantum channel. The sender Alice first performs Bell-state measurements (BSMs) on her qubits pairs respectively and tells her measurement outcome to authorizers Bob to reconstruct the original state, then Charlie should carries out single-qubit measurement (SQM) on his qubits. According to the results from Alice and Charlie, Bob can reconstruct the original state by applying an appropriate unitary operation. After analyzing, the method achieved the desired effect of quantum information splitting (QIS). We also realize the QIS of arbitrary three-qubit state in cavity quantum electrodynamics (QED).
GREEN＇S FUNCTION AND EFFECTIVE ELASTIC STIFFNESS TENSOR FOR ARBITRARY AGGREGATES OF CUBIC CRYSTALS
Institute of Scientific and Technical Information of China (English)
HuangMojia; ZhengChaomei
2004-01-01
A closed but approximate formula of Green's function for an arbitrary aggregate of cubic crystallites is given to derive the effective elastic stiffness tensor of the polycrystal. This formula, which includes three elastic constants of single cubic crystal and five texture coefficients,accounts for the effects of the orientation distribution function (ODF) up to terms linear in the texture coefficients. Thus it is expected that our formula would be applicable to arbitrary aggregates with weak texture or to materials such as aluminum whose single crystal has weak anisotropy.Three examples are presented to compare predictions from our formula with those from Nishioka and Lothe's formula and Synge's contour integral through numerical integration. As an application of Green's function, we briefly describe the procedure of deriving the effective elastic stiffness tensor for an orthorhombic aggregate of cubic crystallites. The comparison of the computational results given by the finite element method and our effective elastic stiffness tensor is made by an example.
Expansion of arbitrary electromagnetic fields in terms of vector spherical wave functions.
Moreira, Wendel Lopes; Neves, Antonio Alvaro Ranha; Garbos, Martin K; Euser, Tijmen G; Cesar, Carlos Lenz
2016-02-01
Since 1908, when Mie reported analytical expressions for the fields scattered by a spherical particle upon incidence of plane-waves, generalizing his analysis for the case of an arbitrary incident wave has been an open question because of the cancellation of the prefactor radial spherical Bessel function. This cancellation was obtained before by our own group for a highly focused beam centered in the objective. In this work, however, we show for the first time how these terms can be canceled out for any arbitrary incident field that satisfies Maxwells equations, and obtain analytical expressions for the beam shape coefficients. We show several examples on how to use our method to obtain analytical beam shape coefficients for: Bessel beams, general hollow waveguide modes and specific geometries such as cylindrical and rectangular. Our method uses the vector potential, which shows the interesting characteristic of being gauge invariant. These results are highly relevant for speeding up numerical calculation of light scattering applications such as the radiation forces acting on spherical particles placed in an arbitrary electromagnetic field, as in an optical tweezers system. PMID:26906812
ARBITRARY INTERACTION OF PLANE SUPERSONIC FLOWS
Directory of Open Access Journals (Sweden)
P. V. Bulat
2015-11-01
Full Text Available Subject of study.We consider the Riemann problem for parameters at collision of two plane flows at a certain angle. The problem is solved in the exact statement. Most cases of interference, both stationary and non-stationary gas-dynamic discontinuities, followed by supersonic flows can be reduced to the problem of random interaction of two supersonic flows. Depending on the ratio of the parameters in the flows, outgoing discontinuities turn out to be shock waves, or rarefactionwaves. In some cases, there is no solution at all. It is important to know how to find the domain of existence for the relevant decisions, as the type of shock-wave structures in these domains is known in advance. The Riemann problem is used in numerical methods such as the method of Godunov. As a rule, approximate solution is used, known as the Osher solution, but for a number of problems with a high precision required, solution of this problem needs to be in the exact statement. Main results.Domains of existence for solutions with different types of shock-wave structure have been considered. Boundaries of existence for solutions with two outgoing shock waves are analytically defined, as well as with the outgoing shock wave and rarefaction wave. We identify the area of Mach numbers and angles at which the flows interact and there is no solution. Specific flows with two outgoing rarefaction waves are not considered. Practical significance. The results supplement interference theory of stationary gas-dynamic discontinuities and can be used to develop new methods of numerical calculation with extraction of discontinuities.
Newtonian Hydrodynamics with Arbitrary Volumetric Sources
Energy Technology Data Exchange (ETDEWEB)
Lowrie, Robert Byron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-11-12
In this note, we derive how to handle mass, momentum, and energy sources for Newtonian hydrodynamics. Much of this is classic, although we’re unaware of a reference that treats mass sources, necessary for certain physics and the method of manufactured solutions. In addition, we felt it important to emphasize that the integral form of the governing equations results in a straightforward treatment of the sources. With the integral form, we’ll demonstrate that there’s no ambiguity between the Lagrangian and Eulerian form of the equations, which is less clear with the differential forms.
Fotouhi, Babak
2014-01-01
In studying network growth, the conventional approach is to devise a growth mechanism, quantify the evolution of a statistic or distribution (such as the degree distribution), and then solve the equations in the steady state (the infinite-size limit). Consequently, empirical studies also seek to verify the steady-state prediction in real data. The caveat concomitant with confining the analysis to this time regime is that no real system has infinite size; most real growing networks are far from the steady state. This underlines the importance of finite-size analysis. In this paper, we consider the shifted-linear preferential attachment as an illustrative example of arbitrary-time network growth analysis. We obtain the degree distribution for arbitrary initial conditions at arbitrary times. We corroborate our theoretical predictions with Monte Carlo simulations.
A general higher-order remap algorithm for ALE calculations
Energy Technology Data Exchange (ETDEWEB)
Chiravalle, Vincent P [Los Alamos National Laboratory
2011-01-05
A numerical technique for solving the equations of fluid dynamics with arbitrary mesh motion is presented. The three phases of the Arbitrary Lagrangian Eulerian (ALE) methodology are outlined: the Lagrangian phase, grid relaxation phase and remap phase. The Lagrangian phase follows a well known approach from the HEMP code; in addition the strain rate andflow divergence are calculated in a consistent manner according to Margolin. A donor cell method from the SALE code forms the basis of the remap step, but unlike SALE a higher order correction based on monotone gradients is also added to the remap. Four test problems were explored to evaluate the fidelity of these numerical techniques, as implemented in a simple test code, written in the C programming language, called Cercion. Novel cell-centered data structures are used in Cercion to reduce the complexity of the programming and maximize the efficiency of memory usage. The locations of the shock and contact discontinuity in the Riemann shock tube problem are well captured. Cercion demonstrates a high degree of symmetry when calculating the Sedov blast wave solution, with a peak density at the shock front that is similar to the value determined by the RAGE code. For a flyer plate test problem both Cercion and FLAG give virtually the same velocity temporal profile at the target-vacuum interface. When calculating a cylindrical implosion of a steel shell, Cercion and FLAG agree well and the Cercion results are insensitive to the use of ALE.
Spin filter for arbitrary spins by substrate engineering
Pal, Biplab; Römer, Rudolf A.; Chakrabarti, Arunava
2016-08-01
We design spin filters for particles with potentially arbitrary spin S≤ft(=1/2,1,3/2,\\ldots \\right) using a one-dimensional periodic chain of magnetic atoms as a quantum device. Describing the system within a tight-binding formalism we present an analytical method to unravel the analogy between a one-dimensional magnetic chain and a multi-strand ladder network. This analogy is crucial, and is subsequently exploited to engineer gaps in the energy spectrum by an appropriate choice of the magnetic substrate. We obtain an exact correlation between the magnitude of the spin of the incoming beam of particles and the magnetic moment of the substrate atoms in the chain desired for opening up of a spectral gap. Results of spin polarized transport, calculated within a transfer matrix formalism, are presented for particles having half-integer as well as higher spin states. We find that the chain can be made to act as a quantum device which opens a transmission window only for selected spin components over certain ranges of the Fermi energy, blocking them in the remaining part of the spectrum. The results appear to be robust even when the choice of the substrate atoms deviates substantially from the ideal situation, as verified by extending the ideas to the case of a ‘spin spiral’. Interestingly, the spin spiral geometry, apart from exhibiting the filtering effect, is also seen to act as a device flipping spins—an effect that can be monitored by an interplay of the system size and the period of the spiral. Our scheme is applicable to ultracold quantum gases, and might inspire future experiments in this direction.
Dynamics of number systems computation with arbitrary precision
Kurka, Petr
2016-01-01
This book is a source of valuable and useful information on the topics of dynamics of number systems and scientific computation with arbitrary precision. It is addressed to scholars, scientists and engineers, and graduate students. The treatment is elementary and self-contained with relevance both for theory and applications. The basic prerequisite of the book is linear algebra and matrix calculus. .
Zero Cycles on Certain Surfaces in Arbitrary Characteristic
Indian Academy of Sciences (India)
G V Ravindra
2006-02-01
Let be a field of arbitrary characteristic. Let be a singular surface defined over with multiple rational curve singularities and suppose that the Chow group of zero cycles of its normalisation $\\overline{S}$ is finite dimensional. We give numerical conditions under which the Chow group of zero cycles of is finite dimensional.
Mathematical model of bisubject qualimetric arbitrary objects evaluation
Morozova, A.
2016-04-01
An analytical basis and the process of formalization of arbitrary objects bisubject qualimetric evaluation mathematical model information spaces are developed. The model is applicable in solving problems of control over both technical and socio-economic systems for objects evaluation using systems of parameters generated by different subjects taking into account their performance and priorities of decision-making.
Electronic interaction anisotropy between atoms in arbitrary angular momentum states
Krems, R.V.; Groenenboom, G.C.; Dalgarno, A.
2004-01-01
A general tensorial expansion for the interaction potential between two atoms in arbitrary angular momentum states is derived and the relations between the expansion coefficients and the Born-Oppenheimer potentials of the diatomic molecule are obtained. It is demonstrated that a complete expansion o
Canonical Quantum Teleportation of Two-Particle Arbitrary State
Institute of Scientific and Technical Information of China (English)
HAO Xiang; ZHU Shi-Qun
2005-01-01
The canonical quantum teleportation of two-particle arbitrary state is realized by means of phase operator and number operator. The maximally entangled eigenstates between the difference of phase operators and the sum of number operators are considered as the quantum channels. In contrast to the standard quantum teleportation, the different unitary local operation of canonical teleportation can be simplified by a general expression.
Quantum electrodynamics with arbitrary charge on a noncommutative space
Institute of Scientific and Technical Information of China (English)
ZHOU Wan-Ping; CAI Shao-Hong; LONG Zheng-Wen
2009-01-01
Using the Seiberg-Witten map,we obtain a quantum electrodynamics on a noncommutative space,which has arbitrary charge and keep the gauge invariance to at the leading order in theta.The one-loop divergence and Compton scattering are reinvestigated.The uoncommutative effects are larger than those in ordinary noncommutative quantum electrodynamics.
Rainbows in the grass. II. Arbitrary diagonal incidence.
Adler, Charles L; Lock, James A; Fleet, Richard W
2008-12-01
We consider external reflection rainbow caustics due to the reflection of light from a pendant droplet where the light rays are at an arbitrary angle with respect to the horizontal. We compare this theory to observation of glare spots from pendant drops on grass; we also consider the potential application of this theory to the determination of liquid surface tension. PMID:19037345
Unveiling Reality of the Mind: Cultural Arbitrary of Consumerism
Choi, Su-Jin
2012-01-01
This paper discusses the cultural arbitrary of consumerism by focusing on a personal realm. That is, I discuss what consumerism appeals to and how it flourishes in relation to our minds. I argue that we need to unveil reality of the mind, be aware of ourselves in relation to the perpetuation of consumerism, in order to critically intervene in the…
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
This paper is based on the fundamental loading model of pure bending and the analytical model of a circular beam element with arbitrary initial deflection. The L.W. Guo solution is modified and generalized according to the elastic theory, and the analytical solution for the stress of the beam element with arbitrary initial deflection under pure bending is derived. Using yield theory of edge strength, an expression for the safety margin of one point in the arbitrary curved beam under pure bending (ACPB) is built. This paper modifies the model for weak points of service structures and establishes a foundation for safe design and inspection of imperfect structures. Also, according to the theory of the method of advanced first-order second-moment(AFOSM), this paper derives an expression for the reliability index of one point in ACPB. Lastly, it modifies the solution for weak points by solving the minimal reliability index.
Institute of Scientific and Technical Information of China (English)
XIE Xuemei
2007-01-01
In this paper, a method is proposed to construct recombination nonuniform cosine-modulated filter banks (CMFBs)with a perfect-reconstruction property and with arbitrary filter lengths. In this filter bank (FB) structure, certain channels of an original M-channel uniform FB are merged by a set of transmultiplexers (TMUXs), yielding nonuniform outputs, and the length restrictions on the original CMFB and the recombination TMUXs are avoided, allowing them to have arbitrary filter lengths. By imposing certain improved matching conditions on the prototype filters, nonuniform FBs with arbitrary filter lengths and with good properties can be obtained.As a result, the flexibility of selecting modulation types and filter lengths is greatly increased in the design of recombination nonuniform CMFBs. Another benefit due to the flexibility is that the system delay can be reduced.
Gomez, Raul; Gomez, Sandra; Marquina, Ma. Luisa
2004-03-01
Most of the Mechanics and Mathematics for Physicists books ignore the problem of obtaining the isochrone (tautochrone) curve in the uniform gravitational field of Earth. A noticeable exception is Arfken's^1 book, which uses the Laplace transform formalism and the convolution theorem to resolve the problem. Through an adequate change of variable, the Laplace transform can be extended in such a way as to be able to apply the convolution theorem. The tautachrone problem for an arbitrary potential energy function can then be resolved. Moreover, the inverse problem of finding the potential function associated with a given arbitrary trajectory can also be established. It is worth noting that the same results can also be obtained using a less known formalism of fractional derivatives ^2. ^1G. Arfken, Mathematical Methods for Physicists. Academic Press (1970) pp 713. ^2Eduardo Flores. The tautochrone under arbitrary potentials using fractional derivatives, Am. J. Phys. 67 (1999) 718-722.
Institute of Scientific and Technical Information of China (English)
冯国胜; 武寄洲; 王晓锋; 郑宁宣; 李玉清; 马杰; 肖连团; 贾锁堂
2015-01-01
We report a robust method of directly stabilizing a grating feedback diode laser to an arbitrary frequency in a large range. The error signal, induced from the difference between the frequency measured by a wavelength meter and the preset target frequency, is fed back to the piezoelectric transducer module of the diode laser via a sound card in the computer. A visual Labview procedure is developed to realize a feedback system. In our experiment the frequency drift of the diode laser is reduced to 8 MHz within 25 min. The robust scheme can be adapted to realize the arbitrary frequency stabilization for many other kinds of lasers.
Energy Technology Data Exchange (ETDEWEB)
Gao, Zao-Chun, E-mail: zcgao@ciae.ac.cn; Hu, Qing-Li; Chen, Y.S.
2014-05-01
Overlap between Hartree–Fock–Bogoliubov (HFB) vacua is very important in the beyond mean-field calculations. However, in the HFB transformation, the U,V matrices are sometimes singular due to the exact emptiness (v{sub i}=0) or full occupation (u{sub i}=0) of some single-particle orbits. This singularity may cause some problem in evaluating the overlap between HFB vacua through Pfaffian. We found that this problem can be well avoided by setting those zero occupation numbers u{sub i}, v{sub i} to some tiny values denoted by ε(>0), which numerically satisfies 1+ε{sup 2}=1 (e.g., ε=10{sup −8} when using the double precision data type). This treatment does not change the HFB vacuum state because u{sub i}{sup 2},v{sub i}{sup 2}=ε{sup 2} are numerically zero relative to 1. Therefore, for arbitrary HFB transformation, we say that the U, V matrices can always be nonsingular. From this standpoint, we present a new convenient Pfaffian formula for the overlap between arbitrary HFB vacua, which is especially suitable for symmetry restoration. Testing calculations have been performed for this new formula. It turns out that our method is reliable and accurate in evaluating the overlap between arbitrary HFB vacua.
Yadav, Rajesh Kumar; Khare, Avinash; Mandal, Bhabani Prasad
2014-01-01
Rationally extended shape invariant potentials in arbitrary D-dimensions are obtained by using point canonical transformation (PCT) method. The bound-state solutions of these exactly solvable potentials can be written in terms of X_m Laguerre or X_m Jacobi exceptional orthogonal polynomials. These potentials are isospectral to their usual counterparts and possess translationally shape invariance property.
Robbins, Joshua; Voth, Thomas
2007-06-01
The eXtended Finite Element Method (X-FEM) is a finite element based discretization technique developed originally to model dynamic crack propagation [1]. Since that time the method has been used for modeling physics ranging from static mesoscale material failure to dendrite growth. Here we adapt the recent advances of Benson et al. [2] and Belytchko et al. [3] to model shock loading of polycrystalline material. Through several demonstration problems we evaluate the method for modeling the shock response of polycrystalline materials at the mesoscale. Specifically, we use the X-FEM to model grain boundaries. This approach allows us to i) eliminate ad-hoc mixture rules for multi-material elements and ii) avoid explicitly meshing grain boundaries. ([1] N. Moes, J. Dolbow, J and T. Belytschko, 1999,``A finite element method for crack growth without remeshing,'' International Journal for Numerical Methods in Engineering, 46, 131-150. [2] E. Vitali, and D. J. Benson, 2006, ``An extended finite element formulation for contact in multi-material arbitrary Lagrangian-Eulerian calculations,'' International Journal for Numerical Methods in Engineering, 67, 1420-1444. [3] J-H Song, P. M. A. Areias and T. Belytschko, 2006, ``A method for dynamic crack and shear band propagation with phantom nodes,'' International Journal for Numerical Methods in Engineering, 67, 868-893.)
Isochronous Liénard-type nonlinear oscillators of arbitrary dimensions
Indian Academy of Sciences (India)
Ajey K Tiwari; A Durga Devi; R Gladwin Pradeep; V K Chandrasekar
2015-11-01
In this paper, we briefly present an overview of the recent developments made in identifying/generating systems of Liénard-type nonlinear oscillators exhibiting isochronous properties, including linear, quadratic and mixed cases and their higher-order generalizations. There exists several procedures/methods in the literature to identify/generate isochronous systems. The application of local as well as nonlocal transformations and -modified Hamiltonian method in identifying and generating systems exhibiting isochronous properties of arbitrary dimensions is also discussed in detail. The identified oscillators include singular and nonsingular Hamiltonian systems and PT-symmetric systems.
Seismic Waves in a Layered Half-Space from an Arbitrary Buried Source
Institute of Scientific and Technical Information of China (English)
MENG Fanshun; WANG Zaishan; LI Jianjun
2003-01-01
In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fourier transforms in a rectangular coordinate system. This method is clear in concept, and the corresponding formulas given in the paper are simple and convenient for marine seismic prospecting and other fields' applications. An example is presented and the calculated results are in good agreement with those of the finite element method (FEM).
Arbitrary vector beams with selective polarization states patterned by tailored polarizing films
International Nuclear Information System (INIS)
A new method of generating arbitrary vector beams with selective polarization states in composite sectors is proposed and experimentally verified by using tailored polarizing film cooperated with a micro-fabricated phase plate. Three examples of the beams are demonstrated in terms of quasi-radially, quasi-azimuthally and alternating radially and azimuthally polarized beams. Polarization states of the beams are measured by a linear polarizer and the experimental results show excellent agreement with the theoretical predictions. The proposed method presents the great advantages of a high degree of freedom in polarization distribution, and easy implementation with low cost. (paper)
International Nuclear Information System (INIS)
We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses recently introduced piecewise linear weight and basis functions in the finite element approximation and it can be applied on arbitrary polygonal (2D) or polyhedral (3D) grids. We first demonstrate some analytical properties of the PWL method and perform a simple mode analysis to compare the PWL method with Palmer's vertex-centered finite-volume method and with a bilinear continuous finite element method. We then show that this new PWL method gives solutions comparable to those from Palmer's. However, since the PWL method produces a symmetric positive-definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids
Hamers, Adrian S.; Portegies Zwart, Simon F.
2016-07-01
We present a method for studying the secular gravitational dynamics of hierarchical multiple systems consisting of nested binaries, which is valid for an arbitrary number of bodies and arbitrary hierarchical structure. We derive the Hamiltonian of the system and expand it in terms of the - assumed to be - small ratios xi of binary separations. At the lowest non-trivial expansion order (quadrupole order, second order in xi), the Hamiltonian consists of terms which, individually, depend on binary pairs. At higher orders, in addition to terms depending on binary pairs, we also find terms which, individually, depend on more than two binaries. In general, at order n in xi, individual terms depend on at most n - 1 binaries. We explicitly derive the Hamiltonian including all terms up and including third order in xi (octupole order), and including the binary pairwise terms up and including fifth order in xi. These terms are orbit averaged, and we present a new algorithm for efficiently solving the equations of motion. This algorithm is highly suitable for studying the secular evolution of hierarchical systems with complex hierarchies, making long-term integrations of such systems feasible. We show that accurate results are obtained for multiplanet systems with semimajor axis ratios as large as ≈0.4, provided that high-order terms are included. In addition to multiplanet systems with a single star, we apply our results to multistar systems with multiple planets.
Hamers, Adrian S
2015-01-01
We present a method for studying the secular gravitational dynamics of hierarchical multiple systems consisting of nested binaries, which is valid for an arbitrary number of bodies and arbitrary hierarchical structure. We derive the Hamiltonian of the system and expand it in terms of the -- assumed to be -- small ratios $x_i$ of binary separations. At the lowest nontrivial expansion order (quadrupole order, second order in $x_i$), the Hamiltonian consists of terms which, individually, depend on binary pairs. At higher orders, in addition to terms depending on binary pairs, we also find terms which, individually, depend on more than two binaries. In general, at order $n$ in $x_i$, individual terms depend on at most $n-1$ binaries. We explicitly derive the Hamiltonian including all terms up and including third order in $x_i$ (octupole order), and including the binary pairwise terms up and including fifth order in $x_i$. These terms are orbit averaged, and we present a new algorithm for efficiently solving the e...
On Black-Brane Instability In an Arbitrary Dimension
Kol, B; Kol, Barak; Sorkin, Evgeny
2004-01-01
The black-hole black-string system is known to exhibit critical dimensions and therefore it is interesting to vary the spacetime dimension $D$, treating it as a parameter of the system. We derive the large $D$ asymptotics of the critical, i.e. marginally stable, string following an earlier numerical analysis. For a background with an arbitrary compactification manifold we give an expression for the critical mass of a corresponding black brane. This expression is completely explicit for ${\\bf T}^n$, the $n$ dimensional torus of an arbitrary shape. An indication is given that by employing a higher dimensional torus, rather than a single compact dimension, the total critical dimension above which the nature of the black-brane black-hole phase transition changes from sudden to smooth could be as low as $D\\leq 11$.
Sunrise: Polychromatic Dust Radiative Transfer in Arbitrary Geometries
Jonsson, P
2006-01-01
This paper describes Sunrise, a parallel, free Monte-Carlo code for the calculation of radiation transfer through astronomical dust. Sunrise uses an adaptive-mesh refinement grid to describe arbitrary geometries of emitting and absorbing/scattering media, with spatial dynamical range exceeding 10^4, and it can efficiently generate images of the emerging radiation at arbitrary points in space. In addition to the monochromatic radiative transfer typically used by Monte-Carlo codes, Sunrise is capable of propagating a range of wavelengths simultaneously. This ``polychromatic'' algorithm gives significant improvements in efficiency and accuracy when spectral features are calculated. Sunrise is used to study the effects of dust in hydrodynamic simulations of interacting galaxies, and the procedure for this is described. The code is tested against previously published results.
Generalization of the electronic susceptibility for arbitrary molecular geometries
Scherrer, Arne; Dreßler, Christian; Ahlert, Paul; Sebastiani, Daniel
2016-04-01
We generalize the explicit representation of the electronic susceptibility χ[R](r, r') for arbitrary molecular geometries R. The electronic susceptibility is a response function that yields the response of the molecular electronic charge density at linear order to an arbitrary external perturbation. We address the dependence of this response function on the molecular geometry. The explicit representation of the molecular geometry dependence is achieved by means of a Taylor expansion in the nuclear coordinates. Our approach relies on a recently developed low-rank representation of the response function χ[R](r, r') which allows a highly condensed storage of the expansion and an efficient application within dynamical chemical environments. We illustrate the performance and accuracy of our scheme by computing the vibrationally induced variations of the response function of a water molecule and its resulting Raman spectrum.
Topological flat band models with arbitrary Chern numbers
Yang, Shuo; Gu, Zheng-Cheng; Sun, Kai; Das Sarma, S.
2012-12-01
We report the theoretical discovery of a systematic scheme to produce topological flat bands (TFBs) with arbitrary Chern numbers. We find that generically a multiorbital high Chern number TFB model can be constructed by considering multilayer Chern number C=1 TFB models with enhanced translational symmetry. A series of models are presented as examples, including a two-band model on a triangular lattice with a Chern number C=3 and an N-band square lattice model with C=N for an arbitrary integer N. In all these models, the flatness ratio for the TFBs is larger than 30 and increases with increasing Chern number. In the presence of appropriate interparticle interactions, these models are likely to lead to the formation of Abelian and non-Abelian fractional Chern insulators. As a simple example, we test the C=2 model with hardcore bosons at 1/3 filling, and an intriguing fractional quantum Hall state is observed.
Locally indistinguishable orthogonal product bases in arbitrary bipartite quantum system
Xu, Guang-Bao; Yang, Ying-Hui; Wen, Qiao-Yan; Qin, Su-Juan; Gao, Fei
2016-08-01
As we know, unextendible product basis (UPB) is an incomplete basis whose members cannot be perfectly distinguished by local operations and classical communication. However, very little is known about those incomplete and locally indistinguishable product bases that are not UPBs. In this paper, we first construct a series of orthogonal product bases that are completable but not locally distinguishable in a general m ⊗ n (m ≥ 3 and n ≥ 3) quantum system. In particular, we give so far the smallest number of locally indistinguishable states of a completable orthogonal product basis in arbitrary quantum systems. Furthermore, we construct a series of small and locally indistinguishable orthogonal product bases in m ⊗ n (m ≥ 3 and n ≥ 3). All the results lead to a better understanding of the structures of locally indistinguishable product bases in arbitrary bipartite quantum system.
Quantum teleportation of an arbitrary superposition of atomic states
Institute of Scientific and Technical Information of China (English)
Chen Qiong; Fang Xi-Ming
2008-01-01
This paper proposes a scheme to teleport an arbitrary multi-particle two-level atomic state between two parties or an arbitrary zero- and one-photon entangled state of multi-mode between two high-Q cavities in cavity QED.This scheme is based on the resonant interaction between atom and cavity and does not involve Bell-state measurement.It investigates the fidelity of this scheme and find out the case of this unity fidelity of this teleportation.Considering the practical case of the cavity decay,this paper finds that the condition of the unity fidelity is also valid and obtains the effect of the decay of the cavity on the successful probability of the teleportation.
Experimental remote preparation of arbitrary photon polarization states
International Nuclear Information System (INIS)
We demonstrate an experiment for remote preparation of arbitrary photon polarization states. With local operations, polarization measurement, and one way classical communication, any states lying on and inside the Poincare sphere can be remotely prepared. For arbitrary pure states, the efficiency is 100% with a communication cost of one entanglement bit and two classical bits. For mixed states, polarization insensitive measurement is introduced and the classical communication cost is one bit. Spontaneous parametric down-conversion (SPDC) is employed as an entanglement source. The remotely prepared qubits are estimated via quantum tomography process and fidelity between the experimentally prepared state and the expected state is considered to test the data. We achieve remote preparation of 13 states with fidelities all above 0.994
Fluid flow over arbitrary bottom topography in a channel
Panda, Srikumar
2016-05-01
In this paper, two-dimensional free surface potential flow over an arbitrary bottom in a channel is considered to analyze the behavior of the free surface profile using linear theory. It is assumed that the fluid is inviscid, incompressible and flow is irrotational. Perturbation analysis in conjunction with Fourier transform technique is employed to determine the first order corrections of some important physical quantities such as free surface profile, velocity potential, etc. From the practical point of view, one arbitrary bottom topography is considered to determine the free surface profile since the free surface profile depends on the bottom topography. It is found that the free surface profile is oscillatory in nature, representing a wave propagating downstream and no wave upstream.
Chou, Chia-Chun
2014-03-14
The complex quantum Hamilton-Jacobi equation-Bohmian trajectories (CQHJE-BT) method is introduced as a synthetic trajectory method for integrating the complex quantum Hamilton-Jacobi equation for the complex action function by propagating an ensemble of real-valued correlated Bohmian trajectories. Substituting the wave function expressed in exponential form in terms of the complex action into the time-dependent Schrödinger equation yields the complex quantum Hamilton-Jacobi equation. We transform this equation into the arbitrary Lagrangian-Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation describing the rate of change in the complex action transported along Bohmian trajectories is simultaneously integrated with the guidance equation for Bohmian trajectories, and the time-dependent wave function is readily synthesized. The spatial derivatives of the complex action required for the integration scheme are obtained by solving one moving least squares matrix equation. In addition, the method is applied to the photodissociation of NOCl. The photodissociation dynamics of NOCl can be accurately described by propagating a small ensemble of trajectories. This study demonstrates that the CQHJE-BT method combines the considerable advantages of both the real and the complex quantum trajectory methods previously developed for wave packet dynamics. PMID:24628169
Energy Technology Data Exchange (ETDEWEB)
Chou, Chia-Chun, E-mail: ccchou@mx.nthu.edu.tw [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
2014-03-14
The complex quantum Hamilton-Jacobi equation-Bohmian trajectories (CQHJE-BT) method is introduced as a synthetic trajectory method for integrating the complex quantum Hamilton-Jacobi equation for the complex action function by propagating an ensemble of real-valued correlated Bohmian trajectories. Substituting the wave function expressed in exponential form in terms of the complex action into the time-dependent Schrödinger equation yields the complex quantum Hamilton-Jacobi equation. We transform this equation into the arbitrary Lagrangian-Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation describing the rate of change in the complex action transported along Bohmian trajectories is simultaneously integrated with the guidance equation for Bohmian trajectories, and the time-dependent wave function is readily synthesized. The spatial derivatives of the complex action required for the integration scheme are obtained by solving one moving least squares matrix equation. In addition, the method is applied to the photodissociation of NOCl. The photodissociation dynamics of NOCl can be accurately described by propagating a small ensemble of trajectories. This study demonstrates that the CQHJE-BT method combines the considerable advantages of both the real and the complex quantum trajectory methods previously developed for wave packet dynamics.
Energy Technology Data Exchange (ETDEWEB)
Greene, Patrick T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schofield, Samuel P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nourgaliev, Robert [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-06-21
A new mesh smoothing method designed to cluster mesh cells near a dynamically evolving interface is presented. The method is based on weighted condition number mesh relaxation with the weight function being computed from a level set representation of the interface. The weight function is expressed as a Taylor series based discontinuous Galerkin projection, which makes the computation of the derivatives of the weight function needed during the condition number optimization process a trivial matter. For cases when a level set is not available, a fast method for generating a low-order level set from discrete cell-centered elds, such as a volume fraction or index function, is provided. Results show that the low-order level set works equally well for the weight function as the actual level set. Meshes generated for a number of interface geometries are presented, including cases with multiple level sets. Dynamic cases for moving interfaces are presented to demonstrate the method's potential usefulness to arbitrary Lagrangian Eulerian (ALE) methods.
Arbitrary-order parasupersymmetric coherent states of quantum harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Fakhri, H. [Faculty of Physics, Tabriz University, Tabriz (Iran, Islamic Republic of) and Research Institute for Fundamental Sciences, Tabriz (Iran, Islamic Republic of)]. E-mail: Hfakhri@ark.tabrizu.ac.ir; Bahadori, M.E. [Faculty of Physics, Tabriz University, Tabriz (IR): Research Institute for Fundamental Sciences, Tabriz (Iran)]. E-mail: Msph0977@ark.tabrizu.ac.ir
2000-10-13
The eigenstates of arbitrary-order parasupersymmetric Hamiltonian p corresponding to a particle with spin p/2 in the presence of a harmonic oscillator potential and constant magnetic field directed along the z-axis are constructed in terms of eigenstates of a one-dimensional harmonic oscillator. Also, parasupersymmetric coherent states with degenerate multiplicity of an ad hoc bosonic annihilation operator of parasupersymmetric eigenstates of the Hamiltonian mentioned above are calculated. (author)
Arbitrary-order parasupersymmetric coherent states of quantum harmonic oscillator
International Nuclear Information System (INIS)
The eigenstates of arbitrary-order parasupersymmetric Hamiltonian p corresponding to a particle with spin p/2 in the presence of a harmonic oscillator potential and constant magnetic field directed along the z-axis are constructed in terms of eigenstates of a one-dimensional harmonic oscillator. Also, parasupersymmetric coherent states with degenerate multiplicity of an ad hoc bosonic annihilation operator of parasupersymmetric eigenstates of the Hamiltonian mentioned above are calculated. (author)
Quantification of Entanglement of Teleportation in Arbitrary Dimensions
Sazim, Sk; Adhikari, Satyabrata; Banerjee, Subhashish; Pramanik, T.
2012-01-01
We study bipartite entangled states in arbitrary dimensions and obtain different bounds for the entanglement measures in terms of teleportation fidelity. We find that there is a simple relation between negativity and teleportation fidelity for pure states but for mixed states, an upper bound is obtained for negativity in terms of teleportation fidelity using convex-roof extension negativity (CREN). However, with this it is not clear how to distinguish betweeen states useful for teleportation ...
Consistency Conditions for Brane Worlds in Arbitrary Dimensions
Leblond, F; Winters, D J; Leblond, Frederic; Myers, Robert C.; Winters, David J.
2001-01-01
We consider ``brane world sum rules'' for compactifications involving an arbitrary number of spacetime dimensions. One of the most striking results derived from such consistency conditions is the necessity for negative tension branes to appear in five--dimensional scenarios. We show how this result is easily evaded for brane world models with more than five dimensions. As an example, we consider a novel realization of the Randall--Sundrum scenario in six dimensions involving only positive tension branes.
Universality and Borel summability of arbitrary quartic tensor models
Delepouve, Thibault; Gurau, Razvan; Rivasseau, Vincent
2016-01-01
We extend the study of \\emph{melonic} quartic tensor models to models with arbitrary quartic interactions. This extension requires a new version of the loop vertex expansion using several species of intermediate fields and iterated Cauchy-Schwarz inequalities. Borel summability is proven, uniformly as the tensor size $N$ becomes large. Every cumulant is written as a sum of explicitly calculated terms plus a remainder, suppressed in $1/N$. Together with the existence of the large $N$ limit of ...
Resonant tunneling in a Luttinger liquid for arbitrary barrier transmission
Huegle, S.; Egger, R.
2003-01-01
A numerically exact dynamical quantum Monte Carlo approach has been developed and applied to transport through a double barrier in a Luttinger liquid with arbitrary transmission. For strong transmission, we find broad Fabry-Perot Coulomb blockade peaks, with a lineshape parametrized by a single parameter, but at sufficiently low temperatures, non-Lorentzian universal lineshapes characteristic of coherent resonant tunneling emerge, even for strong interactions. For weak transmission, our data ...
Cell assemblies at multiple time scales with arbitrary lag distributions
Russo, Eleonora; Durstewitz, Daniel
2016-01-01
Hebb's idea of a cell assembly as the fundamental unit of neural information processing has dominated neuroscience like no other theoretical concept within the past 60 years. A range of different physiological phenomena, from precisely synchronized spiking to broadly simultaneous rate increases, has been subsumed under this term. Yet progress in this area is hampered by the lack of statistical tools that would enable to extract assemblies with arbitrary constellations of time lags, and at mul...
Entangling two oscillators with arbitrary asymmetric initial states
Yang, Chui-Ping; Su, Qi-Ping; Zheng, Shi-Biao; Nori, Franco; Han, Siyuan
2016-01-01
A Hamiltonian is presented, which can be used to convert any asymmetric state $|\\varphi \\rangle_{a}|\\phi \\rangle_{b}$ of two oscillators $a$ and $b$ into an entangled state. Furthermore, with this Hamiltonian and local operations only, two oscillators, initially in any asymmetric initial states, can be entangled with a third oscillator. The prepared entangled states can be engineered with an arbitrary degree of entanglement. A discussion on the realization of this Hamiltonian is given. Numeri...
Multilevel Polarization of Polar Codes Over Arbitrary Discrete Memoryless Channels
Sahebi, Aria G.; Pradhan, S. Sandeep
2011-01-01
It is shown that polar codes achieve the symmetric capacity of discrete memoryless channels with arbitrary input alphabet sizes. It is shown that in general, channel polarization happens in several, rather than only two levels so that the synthesized channels are either useless, perfect or "partially perfect". Any subset of the channel input alphabet which is closed under addition, induces a coset partition of the alphabet through its shifts. For any such partition of the input alphabet, ther...
Generalized Prediction Intervals for Arbitrary Distributed High-Dimensional Data
Kuehn, Steffen
2008-01-01
This paper generalizes the traditional statistical concept of prediction intervals for arbitrary probability density functions in high-dimensional feature spaces by introducing significance level distributions, which provides interval-independent probabilities for continuous random variables. The advantage of the transformation of a probability density function into a significance level distribution is that it enables one-class classification or outlier detection in a direct manner.
Arbitrary Waveform Generator for Quantum Information Processing with Trapped Ions
R. Bowler; Warring, U.; Britton, J. W.; Sawyer, B. C.; Amini, J.
2013-01-01
Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logi...
Bosonization of interacting fermions in arbitrary dimensions / Peter Kopietz
Kopietz, Peter
2006-01-01
This review is a summary of my work (partially in collaboration with Kurt Schoenhammer) on higher-dimensional bosonization during the years 1994-1996. It has been published as a book entitled "Bosonization of interacting fermions in arbitrary dimensions" by Springer Verlag (Lecture Notes in Physics m48, Springer, Berlin, 1997). I have NOT revised this review, so that there is no reference to the literature after 1996. However, the basic ideas underlying the functional bosonization approach ou...
Probabilistic Teleportation of an Arbitrary Two-particle State
Institute of Scientific and Technical Information of China (English)
顾永建; 郑亦庄; 郭光灿
2001-01-01
A scheme for the teleportation of an arbitrary two-particle state via two non-maximally entangled particle pairsis proposed. We show that teleportation can be successfully realized with a certain probability if the receiveradopts an appropriate unitary-reduction strategy. A specific strategy is provided in detail The probability of successful teleportation is determined by the smaller coefficients of the two entangled pairs.
DEFF Research Database (Denmark)
Yura, Harold; Hanson, Steen Grüner
2012-01-01
Methods for simulation of two-dimensional signals with arbitrary power spectral densities and signal amplitude probability density functions are disclosed. The method relies on initially transforming a white noise sample set of random Gaussian distributed numbers into a corresponding set with the......Methods for simulation of two-dimensional signals with arbitrary power spectral densities and signal amplitude probability density functions are disclosed. The method relies on initially transforming a white noise sample set of random Gaussian distributed numbers into a corresponding set...... with the desired spectral distribution, after which this colored Gaussian probability distribution is transformed via an inverse transform into the desired probability distribution. In most cases the method provides satisfactory results and can thus be considered an engineering approach. Several illustrative...
Energy Technology Data Exchange (ETDEWEB)
Hopkins, Matthew Morgan; Moffat, Harry K.; Noble, David R.; Notz, Patrick K.; Subia, Samuel Ramirez
2007-04-01
Aria is a Galerkin finite element based program for solving coupled-physics problems described by systems of PDEs and is capable of solving nonlinear, implicit, transient and direct-to-steady state problems in two and three dimensions on parallel architectures. The suite of physics currently supported by Aria includes the incompressible Navier-Stokes equations, energy transport equation, species transport equations, nonlinear elastic solid mechanics, and electrostatics as well as generalized scalar, vector and tensor transport equations. Additionally, Aria includes support for arbitrary Lagrangian-Eulerian (ALE) and level set based free and moving boundary tracking. Coupled physics problems are solved in several ways including fully-coupled Newton's method with analytic or numerical sensitivities, fully-coupled Newton-Krylov methods, fully-coupled Picard's method, and a loosely-coupled nonlinear iteration about subsets of the system that are solved using combinations of the aforementioned methods. Error estimation, uniform and dynamic h-adaptivity and dynamic load balancing are some of Aria's more advanced capabilities. Aria is based on the Sierra Framework.
STUDY FOR STREAMLINE OF ARBITRARY SHAPED HOMOGENEOUS RESERVOIRS WITH IMPERMEABLE BARRIERS
Institute of Scientific and Technical Information of China (English)
YIN Hong-jun; FU Chun-quan; HE Ying-fu
2006-01-01
The steady-state flow mathematical model of arbitrary shaped homogeneous reservoirs with impermeable barrier is constructed in this paper. By using Boundary Element Method (BEM), the mathematical model is solved. And a streamline generating technique is presented. The figures of streamlines are plotted and analyzed considering the effect of complex boundary and impermeable barriers. Through analyzing, it indicates that the size, shape and orientation of impermeable barriers have various degree of influence on the streamlines. So, if there are impermeable barriers in reservoir according to the geological materials, the influence of impermeable barriers must be considered when adjusting flood pattern and injection strategy.
Institute of Scientific and Technical Information of China (English)
Kun Ma; Junchang Li; Zebin Fan; Jinbin Gui; Yingxiong Qin; Qiguang Zheng
2005-01-01
@@ Based on the calculation formulas of heat treatment temperature field for an arbitrary incident laser intensity distribution, the transformation intensity distribution of CO2 laser beam passing an integrating mirror is studied theoretically and experimentally. The derived formulas are applied in laser heat treatment research which is transformed by optical system, and the theoretical calculation results are compared with experimental results. It is shown that the formulas can be used to calculate the laser heat treatment temperature field accurately, and the calculation speed is obviously faster than the numerical calculation methods with the same precision. The calculation software can be used to select proper experiment parameters.
Terrain following of arbitrary surfaces using a high intensity LED proximity sensor
Energy Technology Data Exchange (ETDEWEB)
Baker, J.E.
1992-01-01
Many robotic operations, e.g., mapping, scanning, feature following, etc., require accurate surface following of arbitrary targets. This paper presents a versatile surface following and mapping system designed to promote hardware, software and application independence, modular development, and upward expandability. These goals are met by: a full, a priori specification of the hardware and software interfaces; a modular system architecture; and a hierarchical surface-data analysis method, permitting application specific tuning at each conceptual level of topological abstraction. This surface following system was fully designed and independently of any specific robotic host, then successfully integrated with and demonstrated on a completely a priori unknown, real-time robotic system. 7 refs.
A General Model for Representing Arbitrary Unsymmetries in Various Types of Network Analysis
DEFF Research Database (Denmark)
Rønne-Hansen, Jan
1997-01-01
When dealing with unsymmetric faults various proposals have been put forward. In general they have been characterized by specific treatment of the single fault in accordance with the structure and impedances involved. The model presented is based on node equations and was originally developed...... for transient stability studies in order to allow for an arbitrary fault representation as seen from the positive sequence network. The method results in impedances -or admittances-combining the negative sequence and zero sequence representation for the symmetrical network with the structure and electrical...... complicated fault situation which has not been treated before for traditional transient stability analysis...
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
By using Schwarz alternating method, this paper presents asimplified alternating algorithm for the problems of two holes having arbitrary shapes and arrangements in an isotropic homogeneous linear elastic infinite region, and obtains stress and displacement fields for random times of iteration. After precision analysis it is found that the results for twenty times of iteration are of very high precision, and those with higher precision can be acquired if the iteration solving is further conducted. The comparison of the results from FEM further proves the reliability of the simplified alternating algorithm presented by this paper.
Institute of Scientific and Technical Information of China (English)
LIN Bing-Sheng; HENG Tai-Hua
2011-01-01
We use the invariant eigen-operator method to study the higher-dimensional harmonic oscillator in a type of generalized noncommutative phase space,and obtain the explicit expression of the energy spectra of the noncommutative harmonic oscillator in arbitrary dimension.It is found that the energy spectra of the higher-dimensional noncommutative harmonic oscillator are equal to the sum of the energy spectra of some 1D harmonic oscillators and some 2D noncommutative harmonic oscillators. We believe that the properties of the harmonic oscillator may reflect some essence of the noncommutative phase space.
Mueller, A. C.
1977-01-01
An analytical first order solution has been developed which describes the motion of an artificial satellite perturbed by an arbitrary number of zonal harmonics of the geopotential. A set of recursive relations for the solution, which was deduced from recursive relations of the geopotential, was derived. The method of solution is based on Von-Zeipel's technique applied to a canonical set of two-body elements in the extended phase space which incorporates the true anomaly as a canonical element. The elements are of Poincare type, that is, they are regular for vanishing eccentricities and inclinations. Numerical results show that this solution is accurate to within a few meters after 500 revolutions.
Solution of mixed convection heat transfer from isothermal in-line fins
Khalilollahi, Amir
1993-11-01
Transient and steady state combined natural and forced convective flows over two in-line finite thickness fins (louvers) in a vertical channel are numerically solved using two methods. The first method of solution is based on the 'Simple Arbitrary Lagrangian Eulerian' (SALE) technique which incorporates mainly two computational phases: (1) a Lagrangian phase in which the velocity field is updated by the effects of all forces, and (2) an Eulerian phase that executes all advective fluxes of mass, momentum and energy. The second method of solution uses the finite element code entitled FIDAP. In the first part, comparison of the results by FIDAP, SALE, and available experimental work were done and discussed for steady state forced convection over louvered fins. Good agreements were deduced between the three sets of results especially for the flow over a single fin. In the second part and in the absence of experimental literature, the numerical predictions were extended to the transient transports and to the opposing flow where pressure drop is reversed. Results are presented and discussed for heat transfer and pressure drop in assisting and opposing mixed convection flows.
A Parallel Monolithic Approach for Fluid-Structure Interaction in a Cerebral Aneurysm
Sahin, Mehmet; Eken, Ali
2014-11-01
A parallel fully-coupled approach has been developed for the fluid-structure interaction problem in a cerebral artery with aneurysm. An Arbitrary Lagrangian-Eulerian formulation based on the side-centered unstructured finite volume method is employed for the governing incompressible Navier-Stokes equations and the classical Galerkin finite element formulation is used to discretize the constitutive law for the Saint Venant-Kirchhoff material in a Lagrangian frame for the solid domain. The time integration method for the structure domain is based on the energy conserving mid-point method while the second-order backward difference is used within the fluid domain. The resulting large-scale algebraic linear equations are solved using a one-level restricted additive Schwarz preconditioner with a block-incomplete factorization within each partitioned sub-domains. The parallel implementation of the present fully coupled unstructured fluid-structure solver is based on the PETSc library. The proposed numerical algorithm is initially validated for several classical benchmark problems and then applied to a more complicated problem involving unsteady pulsatile blood flow in a cerebral artery with aneurysm as a realistic fluid-structure interaction problem encountered in biomechanics. The authors acknowledge financial support from Turkish National Scientific and Technical Research Council through Project Number 112M107.
SIERRA Multimechanics Module: Aria User Manual – Version 4.40
Energy Technology Data Exchange (ETDEWEB)
Notz, Patrick K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Subia, Samuel Ramirez [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hopkins, Matthew M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moffat, Harry K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Noble, David R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Okusanya, Tolulope O. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-05-02
Aria is a Galerkin finite element based program for solving coupled-physics problems described by systems of PDEs and is capable of solving nonlinear, implicit, transient and direct-to-steady state problems in two and three dimensions on parallel architectures. The suite of physics currently supported by Aria includes thermal energy transport, species transport, and electrostatics as well as generalized scalar, vector and tensor transport equations. Additionally, Aria includes support for manufacturing process flows via the incompressible Navier-Stokes equations specialized to a low Reynolds number (Re < 1) regime. Enhanced modeling support of manufacturing processing is made possible through use of either arbitrary Lagrangian- Eulerian (ALE) and level set based free and moving boundary tracking in conjunction with quasi-static nonlinear elastic solid mechanics for mesh control. Coupled physics problems are solved in several ways including fully-coupled Newton’s method with analytic or numerical sensitivities, fully-coupled Newton- Krylov methods and a loosely-coupled nonlinear iteration about subsets of the system that are solved using combinations of the aforementioned methods. Error estimation, uniform and dynamic ℎ-adaptivity and dynamic load balancing are some of Aria’s more advanced capabilities. Aria is based upon the Sierra Framework.
Air-structure coupling features analysis of mining contra-rotating axial flow fan cascade
International Nuclear Information System (INIS)
The interaction between contra-rotating axial flow fan blade and working gas has been studied by means of establishing air-structure coupling control equation and combining Computational Fluid Dynamics (CFD) and Computational solid mechanics (CSM). Based on the single flow channel model, the Finite Volume Method was used to make the field discrete. Additionally, the SIMPLE algorithm, the Standard k-ε model and the Arbitrary Lagrangian-Eulerian dynamic grids technology were utilized to get the airflow motion by solving the discrete governing equations. At the same time, the Finite Element Method was used to make the field discrete to solve dynamic response characteristics of blade. Based on weak coupling method, data exchange from the fluid solver and the solid solver was processed on the coupling interface. Then interpolation was used to obtain the coupling characteristics. The results showed that the blade's maximum amplitude was on the tip of the last-stage blade and aerodynamic force signal could reflect the blade working conditions to some extent. By analyzing the flow regime in contra-rotating axial flow fan, it could be found that the vortex core region was mainly in the blade surface, the hub and the blade clearance. In those regions, the turbulence intensity was very high. The last-stage blade's operating life is shorter than that of the pre-stage blade due to the fatigue fracture occurs much more easily on the last-stage blade which bears more stress
Lee, Sang Hoon; Choi, Hyoung Gwon; Yoo, Jung Yul
2012-11-01
The effect of artery wall hypertrophy and stiffness on the flow field is investigated using three-dimensional finite element method for simulating the blood flow. To avoid the complexity due to the necessity of additional mechanical constraints, we use the combined formulation which includes both the fluid and structural equations of motion into single coupled variational equation. A P2P1 Galerkin finite element method is used to solve the Navier-Stokes equations for fluid flow and arbitrary Lagrangian-Eulerian formulation is used to achieve mesh movement. The Newmark method is employed for solving the dynamic equilibrium equations for linear elastic solid mechanics. The pulsatile, incompressible flows of Newtonian fluids constrained in the flexible wall are analyzed with Womersley velocity profile at the inlet and constant pressure at the outlet. The study shows that the stiffness of carotid artery wall affects significantly the flow phenomena during the pulse cycle. Similarly, it is found that the flow field is also strongly influenced by wall hypertrophy. This work was supported by Mid-career Researcher Program and Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0079936 & 2011-0029613).
Energy Technology Data Exchange (ETDEWEB)
Bailey, T.S.; Adams, M.L. [Texas A M Univ., Dept. of Nuclear Engineering, College Station, TX (United States); Yang, B.; Zika, M.R. [Lawrence Livermore National Lab., Livermore, CA (United States)
2005-07-01
We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2-dimensional) or polyhedral (3-dimensional) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids. (authors)
Energy Technology Data Exchange (ETDEWEB)
Bailey, T S; Adams, M L; Yang, B; Zika, M R
2005-07-15
We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2D) or polyhedral (3D) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, it should be substantially more computationally efficient than Palmer's method, which produces an asymmetric matrix. We conclude that the Galerkin PWL method is an attractive option for solving diffusion equations on unstructured grids.
基于光学全息的任意矢量光的生成方法∗%Generation of arbitrary vector b eam based on optical holography
Institute of Scientific and Technical Information of China (English)
席思星; 王晓雷; 黄帅; 常胜江; 林列
2015-01-01
According to the phase and amplitude modulation of the spatial light modulator (SLM) loading the phase distribu-tion for generating arbitrary vector beams, we present a method of generating arbitrary vector beams based on the optical holography with angle multiplexing. First of all, we use the optical holography to record the special phase distribution on the SLM, and so an optical holographic grating is obtained. In the reproduction process, the two conjugate reference beams with the same incident angle illuminate the holographic grating and the superposition of the two reproduced beams is achieved, thus the arbitrary vector beams are obtained. This method can avoid the emergence of complex polarization distribution, and has advantages such as simple optical setup, convenient operation, and higher polarization purity of generated arbitrary vector beams. Good results of the arbitrary vector beams are also obtained by computer simulation.
Directory of Open Access Journals (Sweden)
Davtyan A.V.
2014-09-01
Full Text Available In present paper is considered the problem of penetration of the pressure in an isotropic elastic half-plane, boundary of which has the rigid support moving with arbitrary velocity. Solution of the plane problem is sought by method of integral transforms Laplace, Fourier and by method of the convolutions. Partial problems about a shock wave propagating along the boundary half-plane are solved. The stress intensity factors, stress on the line of contact is calculated.
Li, Z. J.; Wu, Z. S.; Qu, T.; Shang, Q. C.; Bai, L.
2016-01-01
Based on the generalized multiparticle Mie theory, multiple scattering of an aggregate of uniaxial anisotropic spheres illuminated by a zero-order Bessel beam (ZOBB) with arbitrary propagation direction is investigated. The particle size and configuration are arbitrary. The arbitrary incident Bessel beam is expanded in terms of spherical vector wave functions (SVWFs). Utilizing the vector addition theorem of SVWFs, interactive and total scattering coefficients are derived through the continuous boundary conditions on which the interaction of the particles is considered. The accuracy of the theory and codes are verified by comparing results with those obtained for arbitrary plane wave incidence by CST simulation, and for ZOBB incidence by a numerical method. The effects of angle of incidence, pseudo-polarization angle, half-conical angle, beam center position, and permittivity tensor elements on the radar cross sections (RCSs) of several types of collective uniaxial anisotropic spheres, such as a linear chain, a 4×4×4 cube-shaped array, and other periodical structures consisting of massive spheres, are numerically analyzed. Selected results on the properties of typical particles such as TiO2, SiO2, or other particle lattices are calculated. This investigation could provide an effective test for further research on the scattering characteristics of an aggregate of anisotropic spheres by a high-order Bessel vortex beam. The results have important application in optical tweezers and particle manipulation.
Optimal O(1 Bilateral Filter with Arbitrary Spatial and Range Kernels Using Sparse Approximation
Directory of Open Access Journals (Sweden)
Shengdong Pan
2014-01-01
Full Text Available A number of acceleration schemes for speeding up the time-consuming bilateral filter have been proposed in the literature. Among these techniques, the histogram-based bilateral filter trades the flexibility for achieving O(1 computational complexity using box spatial kernel. A recent study shows that this technique can be leveraged for O(1 bilateral filter with arbitrary spatial and range kernels by linearly combining the results of multiple-box bilateral filters. However, this method requires many box bilateral filters to obtain sufficient accuracy when approximating the bilateral filter with a large spatial kernel. In this paper, we propose approximating arbitrary spatial kernel using a fixed number of boxes. It turns out that the multiple-box spatial kernel can be applied in many O(1 acceleration schemes in addition to the histogram-based one. Experiments on the application to the histogram-based acceleration are presented in this paper. Results show that the proposed method has better accuracy in approximating the bilateral filter with Gaussian spatial kernel, compared with the previous histogram-based methods. Furthermore, the performance of the proposed histogram-based bilateral filter is robust with respect to the parameters of the filter kernel.
Finite element analysis of multilayer coextrusion.
Energy Technology Data Exchange (ETDEWEB)
Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A. (Proctor & Gamble Company, West Chester, OH); Mrozek, Randy A. (Army Research Laboratory, Adelphi, MD); Lenhart, Joseph Ludlow (Army Research Laboratory, Adelphi, MD); Rao, Rekha Ranjana; Collins, Robert (Oak Ridge National Laboratory); Mondy, Lisa Ann
2011-09-01
Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.
Failure Prediction in Bulk Metal Forming Process
Directory of Open Access Journals (Sweden)
Ameen Topa
2014-01-01
Full Text Available An important concern in metal forming is whether the desired deformation can be accomplished without defects in the final product. Various ductile fracture criteria have been developed and experimentally verified for a limited number of cases of metal forming processes. These criteria are highly dependent on the geometry of the workpiece and cannot be utilized for complicated shapes without experimental verification. However, experimental work is a resource hungry process. This paper proposes the ability of finite element analysis (FEA software such as LS-DYNA to pinpoint the crack-like flaws in bulk metal forming products. Two different approaches named as arbitrary Lagrangian-Eulerian (ALE and smooth particle hydrodynamics (SPH formulations were adopted. The results of the simulations agree well with the experimental work and a comparison between the two formulations has been carried out. Both approximation methods successfully predicted the flow of workpiece material (plastic deformation. However ALE method was able to pinpoint the location of the flaws.
Simulating Pediatric Ventricular Assist Device Operation Using Fluid Structure Interaction
Long, Chris; Bazilevs, Yuri; Marsden, Alison
2012-11-01
Ventricular Assist Devices (VADs) provide mechanical circulatory support to patients in heart failure. They are primarily used to extend life until cardiac transplant, but also show promise as a ``bridge-to-recovery'' device in pediatric patients. Commercially available pediatric pumps are pulsatile displacement pumps, with two distinct chambers for air and blood separated by a thin, flexible membrane. The air chamber pneumatically drives the membrane, which drives blood through the other chamber via displacement. The primary risk factor associated with these devices is stroke or embolism due to thrombogenesis in the blood chamber, occurring in as many as 40% of patients. Our goal is to perform simulations that accurately model the hemodynamics of the device, as well as the non-linear membrane buckling. We apply a finite-element based fluid solver, with an Arbitrary Lagrangian-Eulerian (ALE) framework to account for mesh motion. Isogeometric Analysis with a Kirchhoff-Love shell formulation is used on the membrane, and two distinct fluid subdomains are used for the air and blood chambers. The Fluid Structure Interaction (FSI) problem is solved simultaneously, using a Matrix Free method to model the interactions at the fluid-structure boundary. Methods and results are presented.
Institute of Scientific and Technical Information of China (English)
HONG Taehyup; KIM Chang Nyung
2011-01-01
The effects of implantation angles of Bileaflet Mechanical Heart Valves (BMHVs) on the blood flow and the leaflet motion are investigated in this paper.The physiological blood flow interacting with the moving leaflets ofa BMHV is simulated with a strongly coupled implicit Fluid-Structure Interaction (FSI) method based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (remeshing) in Fluent.BMHVs are widely used to be implanted to replace the diseascd heart valves,but the patients would suffer from some complications such as hemolysis,platelet activation,tissue overgrowth and device failure.These complications are closely related to both the flow characteristics near the valves and the leaflet dynamics.The currentnumerical model is validated against a previous experimental study.The numerical results show that as the rotation angle of BMHV is increased the degree of asymmetry of the blood flow and the leaflet motion is increased,which may lead to an unbalanced force acting on the BMHVs.This study shows the applicability of the FSI model for the interaction between the blood flow and the leaflet motion in BMHVs.
Interpretation of the lime column penetration test
Liyanapathirana, D. S.; Kelly, R. B.
2010-06-01
Dry soil mix (DSM) columns are used to reduce the settlement and to improve the stability of embankments constructed on soft clays. During construction the shear strength of the columns needs to be confirmed for compliance with technical assumptions. A specialized blade shaped penetrometer known as the lime column probe, has been developed for testing DSM columns. This test can be carried out as a pull out resistance test (PORT) or a push in resistance test (PIRT). The test is considered to be more representative of average column shear strength than methods that test only a limited area of the column. Both PORT and PIRT tests require empirical correlations of measured resistance to an absolute measure of shear strength, in a similar manner to the cone penetration test. In this paper, finite element method is used to assess the probe factor, N, for the PORT test. Due to the large soil deformations around the probe, an Arbitrary Lagrangian Eulerian (ALE) based finite element formulation has been used. Variation of N with rigidity index and the friction at the probe-soil interface are investigated to establish a range for the probe factor.
Cold sprayed copper coating: numerical study of particle impact and coating characterization
Mebdoua, Yamina; Fizi, Yazid; Bouhelal, Nadjet
2016-05-01
Cold spraying technique is a promising process fabricating high quality metallic coatings. This work concerns both numerical and experimental investigations of cold sprayed copper coating taking into account impact conditions including, particle velocities and temperature, gas pressure and material nature. The conducted numerical study is an examination of the deformation behavior of Cu particles sprayed onto steel substrate using Abaqus/explicit software, allowing a good understanding of the deposition characteristics of copper particles and the effect of particle velocity on the coating microstructure. The numerical results show that particle impact velocity has a significant effect on its morphology; Lagrangian method exhibits an excessive distortion of the elements in the case of high impact velocity and fine meshing size, whereas simulation of particle impact using arbitrary Lagrangian-Eulerian (ALE) method is close to the experimental observations. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui
ALTERNATIVE MODEL FOR NONLINEAR WATER WAVES OVER ARBITRARY DEPTHS
Institute of Scientific and Technical Information of China (English)
Huang Hu
2003-01-01
To account for effects of nonlinearty on the wave-propagation characteristics, by using Green's second identity a nonlinear consistent equation for water waves propagating over arbitrary depths is derived by introducing a function as approximation to the exact velocity protential function for the nonlinear governing equations, which can be simplified to teh linear uniform mild-slope equation given by Zhang and Edge[7] recently. In shallow water the equation reduces to a nonlinear equation of Boussinesq-type. In deep water the nonlinear dispersion relation for Stokes expansion is found.
Arbitrary Multicolor Photodetection by Hetero-integrated Semiconductor Nanostructures
Liwen Sang; Junqing Hu; Rujia Zou; Yasuo Koide; Meiyong Liao
2013-01-01
The typical photodetectors can only detect one specific optical spectral band, such as InGaAs and graphene-PbS quantum dots for near-infrared (NIR) light detection, CdS and Si for visible light detection, and ZnO and III-nitrides for UV light detection. So far, none of the developed photodetector can achieve the multicolor detection with arbitrary spectral selectivity, high sensitivity, high speed, high signal-to-noise ratio, high stability, and simplicity (called 6S requirements). Here, we p...
Revenue comparisons for auctions when bidders have arbitrary types
Directory of Open Access Journals (Sweden)
Yeon-Koo Che
2006-03-01
Full Text Available This paper develops a methodology for characterizing expected revenue from auctions when bidders' types come from an arbitrary distribution. In particular, types may be multidimensional, and there may be mass points in the distribution. One application extends existing revenue equivalence results. Another application shows that first-price auctions yield higher expected revenue than second-price auctions when bidders are risk averse and face financial constraints. This revenue ranking extends to risk-averse bidders with general forms of non-expected utility preferences.
The entropic squeezing of superposition of two arbitrary coherent states
Institute of Scientific and Technical Information of China (English)
Lu Dao-Ming
2008-01-01
In this paper the superpusitious of two arbitrary coherent states |ψ>= α|β>+bei4 |mβei(o)> are constructed by using the superposition principle of quantum mechanics.The entropic squeezing effects of the quantum states are studied.The numerical results indicate that the amplitudes,the ratio between the amplitudes of two coherent states,the phase difference between the two components and the relative phase of the two coefficients play important roles in the squeezing effects of the position entropy and momentum entropy.
Controlling electromagnetic fields at boundaries of arbitrary geometries
Teo, Jonathon Yi Han; Wong, Liang Jie; Molardi, Carlo; Genevet, Patrice
2016-08-01
Rapid developments in the emerging field of stretchable and conformable photonics necessitate analytical expressions for boundary conditions at metasurfaces of arbitrary geometries. Here, we introduce the concept of conformal boundary optics: a design theory that determines the optical response for designer input and output fields at such interfaces. Given any object, we can realize coatings to achieve exotic effects like optical illusions and anomalous diffraction behavior. This approach is relevant to a broad range of applications from conventional refractive optics to the design of the next-generation of wearable optical components. This concept can be generalized to other fields of research where designer interfaces with nontrivial geometries are encountered.
Controlling Electromagnetic Fields at Boundaries of Arbitrary Geometries
Teo, Jonathon Yi Han; Molardi, Carlo; Genevet, Patrice
2015-01-01
Rapid developments in the emerging field of stretchable and conformable photonics necessitate analytical expressions for boundary conditions at metasurfaces of arbitrary geometries. Here, we introduce the concept of conformal boundary optics: a design theory that determines the optical response for designer input and output fields at such interfaces. Given any object, we can realise coatings to achieve exotic effects like optical illusions and anomalous diffraction behaviour. This approach is relevant to a broad range of applications from conventional refractive optics to the design of the next-generation of wearable optical components. This concept can be generalized to other fields of research where designer interfaces with nontrivial geometries are encountered.
Teleportation of an arbitrary three-particle state
Institute of Scientific and Technical Information of China (English)
陈立冰
2002-01-01
We propose two schemes for teleporting an arbitrary three-particle state. In the first scheme, a two-particle state and a three-particle entangled state (both non-maximally entangled states) are used as quantum channels, while in the second scheme, three non-maximally entangled particle pairs are employed as quantum channels. We show that teleportation can be successfully realized with certain probability if a receiver adopts some appropriate unitary transformations. Their success probabilities and the classical communication costs are different.
A Novel Memory Compress Algorithm for Arbitrary Waveform Generator
Institute of Scientific and Technical Information of China (English)
吕铁良; 仇玉林
2000-01-01
A memory compress algorithm for 12-bit Arbitrary Waveform Generator (AWG) is presented and optimized. It can compress waveform memory for a sinusoid to 16× 13hits with a Spurious-Free Dynamic Range (SFDR) 90.7dBc (1/1890 of uncompressed memory at the same SFDR) and to 8× 12bits with a SFDR 79dBc. Its hardware cost is six adders and two multipliers. Exploiting this memory compress technique makes it possible to build a high performance AWG on a chip.
Creating arbitrary arrays of two-dimensional topological defects
Murray, Bryce S.; Pelcovits, Robert A.; Rosenblatt, Charles
2014-11-01
An atomic force microscope was used to scribe a polyimide-coated substrate with complex patterns that serve as an alignment template for a nematic liquid crystal. By employing a sufficiently large density of scribe lines, two-dimensional topological defect arrays of arbitrary defect strength were patterned on the substrate. When used as the master surface of a liquid crystal cell, in which the opposing slave surface is treated for planar degenerate alignment, the liquid crystal adopts the pattern's alignment with a disclination line emanating at the defect core on one surface and terminating at the other surface.
A generalization of the Virasoro algebra to arbitrary dimensions
Energy Technology Data Exchange (ETDEWEB)
Gurau, Razvan, E-mail: rgurau@perimeterinstitute.ca [Perimeter Institute for Theoretical Physics, 31 Caroline St. N, ON N2L 2Y5, Waterloo (Canada)
2011-11-21
Colored tensor models generalize matrix models in higher dimensions. They admit a 1/N expansion dominated by spherical topologies and exhibit a critical behavior strongly reminiscent of matrix models. In this paper we generalize the colored tensor models to colored models with generic interaction, derive the Schwinger Dyson equations in the large N limit and analyze the associated algebra of constraints satisfied at leading order by the partition function. We show that the constraints form a Lie algebra (indexed by trees) yielding a generalization of the Virasoro algebra in arbitrary dimensions.
Isotropy theorem for arbitrary-spin cosmological fields
Cembranos, J A R; Jareño, S J Núñez
2013-01-01
We show that the energy-momentum tensor of homogeneous fields of arbitrary spin in an expanding universe is always isotropic in average provided the fields remain bounded and evolve rapidly compared to the rate of expansion. An analytic expression for the average equation of state is obtained for Lagrangians with generic power-law kinetic and potential terms. As an example we consider the behavior of a spin-two field in the standard Fierz-Pauli theory of massive gravity. The results can be extended to general space-time geometries for locally inertial observers.
Quantum Simulations of One-Dimensional Nanostructures under Arbitrary Deformations
Koskinen, Pekka
2016-09-01
A powerful technique is introduced for simulating mechanical and electromechanical properties of one-dimensional nanostructures under arbitrary combinations of bending, twisting, and stretching. The technique is based on an unconventional control of periodic symmetry which eliminates artifacts due to deformation constraints and quantum finite-size effects and allows transparent electronic-structure analysis. Via density-functional tight-binding implementation, the technique demonstrates its utility by predicting nonlinear electromechanical properties in carbon nanotubes and abrupt behavior in the structural yielding of Au7 and Mo6 S6 nanowires. The technique drives simulations markedly closer to the realistic modeling of these slender nanostructures under experimental conditions.
A Proof for a Theorem of Wald in Arbitrary Dimensions
Tan, H S
2009-01-01
Static, axisymmetric solutions form a large class of important black holes in classical GR. In four dimensions, the existence of their most general metric ansatz relies on the fact that two-dimensional subspaces of the tangent space at each point spanned by vectors orthogonal to the time-translation and rotation Killing fields are integrable. This was first proved by Wald via an application of Frobenius theorem. In this note, we furnish an elementary proof for this theorem by Wald in arbitrary dimensions which yields the metric ansatz for the most general solution of the D-dimensional vacuum Einstein equations that admits D-2 orthogonal and commuting Killing vector fields.
Mitri, F G
2016-04-01
One of the fundamental theorems in (optical, acoustical, quantum, gravitational) wave scattering is the optical theorem for plane waves, which relates the extinction cross-section to the forward scattering complex amplitude function. In this analysis, the optical theorem is extended for the case of 3D-beams of arbitrary character in a cylindrical coordinates system for any angle of incidence and any scattering angle. Generalized analytical expressions for the extinction, absorption, scattering cross-sections and efficiency factors are derived in the framework of the scalar resonance scattering theory for an object of arbitrary shape. The analysis reveals the presence of an interference scattering cross-section term, which describes interference between the diffracted or specularly reflected inelastic (Franz) waves with the resonance elastic waves. Moreover, an alternate expression for the extinction cross-section, which relates the resonance cross-section with the scattering cross-section for an impenetrable object, is obtained, suggesting an improved method for particle characterization. Cross-section expressions are also derived for known acoustical wavefronts centered on the object, defined as the on-axis case. The extended optical theorem in cylindrical coordinates can be applied to evaluate the extinction efficiency from any object of arbitrary geometry placed on or off the axis of the incident beam. Applications in acoustics, optics, and quantum mechanics should benefit from this analysis in the context of wave scattering theory and other phenomena closely connected to it, such as the multiple scattering by many particles, as well as the radiation force and torque.
Mitri, F G
2016-04-01
One of the fundamental theorems in (optical, acoustical, quantum, gravitational) wave scattering is the optical theorem for plane waves, which relates the extinction cross-section to the forward scattering complex amplitude function. In this analysis, the optical theorem is extended for the case of 3D-beams of arbitrary character in a cylindrical coordinates system for any angle of incidence and any scattering angle. Generalized analytical expressions for the extinction, absorption, scattering cross-sections and efficiency factors are derived in the framework of the scalar resonance scattering theory for an object of arbitrary shape. The analysis reveals the presence of an interference scattering cross-section term, which describes interference between the diffracted or specularly reflected inelastic (Franz) waves with the resonance elastic waves. Moreover, an alternate expression for the extinction cross-section, which relates the resonance cross-section with the scattering cross-section for an impenetrable object, is obtained, suggesting an improved method for particle characterization. Cross-section expressions are also derived for known acoustical wavefronts centered on the object, defined as the on-axis case. The extended optical theorem in cylindrical coordinates can be applied to evaluate the extinction efficiency from any object of arbitrary geometry placed on or off the axis of the incident beam. Applications in acoustics, optics, and quantum mechanics should benefit from this analysis in the context of wave scattering theory and other phenomena closely connected to it, such as the multiple scattering by many particles, as well as the radiation force and torque. PMID:26836290
Generalized Remote Preparation of Arbitrary m-qubit Entangled States via Genuine Entanglements
Directory of Open Access Journals (Sweden)
Dong Wang
2015-03-01
Full Text Available Herein, we present a feasible, general protocol for quantum communication within a network via generalized remote preparation of an arbitrary m-qubit entangled state designed with genuine tripartite Greenberger–Horne–Zeilinger-type entangled resources. During the implementations, we construct novel collective unitary operations; these operations are tasked with performing the necessary phase transfers during remote state preparations. We have distilled our implementation methods into a five-step procedure, which can be used to faithfully recover the desired state during transfer. Compared to previous existing schemes, our methodology features a greatly increased success probability. After the consumption of auxiliary qubits and the performance of collective unitary operations, the probability of successful state transfer is increased four-fold and eight-fold for arbitrary two- and three-qubit entanglements when compared to other methods within the literature, respectively. We conclude this paper with a discussion of the presented scheme for state preparation, including: success probabilities, reducibility and generalizability.
Generalized warping effect in the dynamic analysis of beams of arbitrary cross section
Dikaros, I. C.; Sapountzakis, E. J.; Argyridi, A. K.
2016-05-01
In this paper a general formulation for the nonuniform warping dynamic analysis of beams of arbitrary simply or multiply connected cross section, under arbitrary external loading and general boundary conditions is presented taking into account the effects of rotary and warping inertia. The nonuniform warping distributions are taken into account by employing four independent warping parameters multiplying a shear warping function in each direction and two torsional warping functions, respectively, which are obtained by solving the corresponding boundary value problems, formulated exploiting the longitudinal local equilibrium equation. A shear stress "correction" is also performed in order to improve the stress field arising from the employed kinematical considerations. Ten initial boundary value problems are formulated with respect to the displacement and rotation components as well as to the independent warping parameters and solved using the Analog Equation Method, a Boundary Element Method based technique in combination with an appropriate time integration scheme. The warping functions and the geometric constants including the additional ones due to warping are evaluated employing a pure BEM approach.
An intrinsic algorithm for parallel Poisson disk sampling on arbitrary surfaces.
Ying, Xiang; Xin, Shi-Qing; Sun, Qian; He, Ying
2013-09-01
Poisson disk sampling has excellent spatial and spectral properties, and plays an important role in a variety of visual computing. Although many promising algorithms have been proposed for multidimensional sampling in euclidean space, very few studies have been reported with regard to the problem of generating Poisson disks on surfaces due to the complicated nature of the surface. This paper presents an intrinsic algorithm for parallel Poisson disk sampling on arbitrary surfaces. In sharp contrast to the conventional parallel approaches, our method neither partitions the given surface into small patches nor uses any spatial data structure to maintain the voids in the sampling domain. Instead, our approach assigns each sample candidate a random and unique priority that is unbiased with regard to the distribution. Hence, multiple threads can process the candidates simultaneously and resolve conflicts by checking the given priority values. Our algorithm guarantees that the generated Poisson disks are uniformly and randomly distributed without bias. It is worth noting that our method is intrinsic and independent of the embedding space. This intrinsic feature allows us to generate Poisson disk patterns on arbitrary surfaces in IR(n). To our knowledge, this is the first intrinsic, parallel, and accurate algorithm for surface Poisson disk sampling. Furthermore, by manipulating the spatially varying density function, we can obtain adaptive sampling easily.
Numerical Simulation for Blast Analysis of Insulating Glass in a Curtain Wall
Deng, Rong-bing; Jin, Xian-long
2010-04-01
This article presents a three-dimensional numerical simulation method for blast response calculation of insulating glass in a curtain wall based on multi-material arbitrary Lagrangian-Eulerian (ALE) formulation and high-performance computer. The whole analytical model consists of explosion, air, curtain wall system, and ground. In particular, detailed components including insulating glass panels, aluminum column, silicone sealant, and other parts in the curtain wall are set up in terms of actual size and actual assembly. This model takes account of the coupling between blast and structure, nonlinear material behavior, brittle failure of glass material, and non-reflecting boundary definition. Final calculation has been performed on the Dawning 4000A supercomputer using the finite-element code LS-DYNA 971 MPP. The propagation of shock wave in air and blast-structure interaction is quite well estimated by numerical calculation. The damage regions of outer and inner glass are reproduced in the numerical simulations, which are in agreement with the experimental observations. The result provides a global understanding of insulating glass panels under blast loading in the curtain wall system. It may be generated to supplement experimental studies for developing appropriate design guidelines for curtain wall systems as well.
Fluid-structure interaction analysis of the drop impact test for helicopter fuel tank.
Yang, Xianfeng; Zhang, Zhiqiang; Yang, Jialing; Sun, Yuxin
2016-01-01
The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid-structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian-Eulerian method was constructed to elucidate the dynamic failure behavior. The drop impact tests were conducted to validate the accuracy of the numerical simulation. Good agreement was achieved between the experimental and numerical results of the impact force with the ground. The influences of the impact velocity, the impact angle, the thickness of the fuel tank wall and the volume fraction of water on the dynamic responses of the dropped fuel tank were studied. The results indicated that the corner of the fuel tank is the most vulnerable location during the impact with ground.
Ebrahimi, Mohsen; Abbaspour, Madjid
2015-01-01
The hydrodynamics and energetics of bioinspired oscillating mechanisms have received significant attentions by engineers and biologists to develop the underwater and air vehicles. Undulating and pure heaving (or plunging) motions are two significant mechanisms which are utilized in nature to provide propulsive, maneuvering, and stabilization forces. This study aims to elucidate and compare the propulsive vortical signature and performance of these two important natural mechanisms through a systematic numerical study. Navier-Stokes equations are solved, by a pressure-based finite volume method solver, in an arbitrary Lagrangian-Eulerian (ALE) framework domain containing a 2D NACA0012 foil moving with prescribed kinematics. Some of the important findings are (1) the thrust production of the heaving foil begins at lower St and has a greater growing slope with respect to the St; (2) the undulating mechanism has some limitations to produce high thrust forces; (3) the undulating foil shows a lower power consumption and higher efficiency; (4) changing the Reynolds number (Re) in a constant St affects the performance of the oscillations; and (5) there is a distinguishable appearance of leading edge vortices in the wake of the heaving foil without observable ones in the wake of the undulating foil, especially at higher St. PMID:27057133
Fluid Structure Interaction Simulations of Pediatric Ventricular Assist Device Operation
Long, Chris; Marsden, Alison; Bazilevs, Yuri
2011-11-01
Pediatric ventricular assist devices (PVADs) are used for mechanical circulatory support in children with failing hearts. They can be used to allow the heart to heal naturally or to extend the life of the patient until transplant. A PVAD has two chambers, blood and air, separated by a flexible membrane. The air chamber is pressurized, which drives the membrane and pumps the blood. The primary risk associated with these devices is stroke or embolism from thrombogenesis. Simulation of these devices is difficult due to a complex coupling of two fluid domains and a thin membrane, requiring fluid-structure interaction modeling. The goal of this work is to accurately simulate the hemodynamics of a PVAD. We perform FSI simulations using an Arbitrary Lagrangian-Eulerian (ALE) finite element framework to account for large motions of the membrane and the fluid domains. The air, blood, and membrane are meshed as distinct subdomains, and a method for non-matched discretizations at the fluid-structure interface is presented. The use of isogeometric analysis to model the membrane mechanics is also discussed, and the results of simulations are presented.
Steady-state and dynamic models for particle engulfment during solidification
Tao, Yutao; Yeckel, Andrew; Derby, Jeffrey J.
2016-06-01
Steady-state and dynamic models are developed to study the physical mechanisms that determine the pushing or engulfment of a solid particle at a moving solid-liquid interface. The mathematical model formulation rigorously accounts for energy and momentum conservation, while faithfully representing the interfacial phenomena affecting solidification phase change and particle motion. A numerical solution approach is developed using the Galerkin finite element method and elliptic mesh generation in an arbitrary Lagrangian-Eulerian implementation, thus allowing for a rigorous representation of forces and dynamics previously inaccessible by approaches using analytical approximations. We demonstrate that this model accurately computes the solidification interface shape while simultaneously resolving thin fluid layers around the particle that arise from premelting during particle engulfment. We reinterpret the significance of premelting via the definition an unambiguous critical velocity for engulfment from steady-state analysis and bifurcation theory. We also explore the complicated transient behaviors that underlie the steady states of this system and posit the significance of dynamical behavior on engulfment events for many systems. We critically examine the onset of engulfment by comparing our computational predictions to those obtained using the analytical model of Rempel and Worster [29]. We assert that, while the accurate calculation of van der Waals repulsive forces remains an open issue, the computational model developed here provides a clear benefit over prior models for computing particle drag forces and other phenomena needed for the faithful simulation of particle engulfment.
Directory of Open Access Journals (Sweden)
Badis Haddag
2016-08-01
Full Text Available In this paper, machining aeronautical aluminum alloy AA2024-T351 in dry conditions was investigated. Cutting forces, chip segmentation, and built-up edge formation were analyzed. Machining tests revealed that the chip formation process depends on cutting conditions and tool geometry. So continuous and segmented chips are generated. Under some cutting conditions, built-up edge formation occurs. A predictive machining theory, based on a finite elements method (FEM, was applied to reproduce and explain these phenomena. Thermomechanical behaviors of the work material and the tool-work material interface were considered. Results of the proposed modelling were compared to experimental data for a wide range of cutting speed. It was shown that the feed force is well reproduced by the ALE-FE (arbitrary lagrangian-eulerian finite element formulation and highly underestimated by the lagrangian finite element (LAG-FE one. While, the periodic localized shear band, leading to a chip segmentation, is well reproduced with the Lagrangian FE formulation. It was found that the chip segmentation can be correlated to the cutting force evolution using the defined chip segmentation intensity parameter. For the built-up edge (BUE phenomenon, it was shown that it depends on the contact/friction at the tool-chip interface, and this is possible to simulate by making the friction coefficient time-dependent.
Flux-corrected transport principles, algorithms, and applications
Löhner, Rainald; Turek, Stefan
2012-01-01
Many modern high-resolution schemes for Computational Fluid Dynamics trace their origins to the Flux-Corrected Transport (FCT) paradigm. FCT maintains monotonicity using a nonoscillatory low-order scheme to determine the bounds for a constrained high-order approximation. This book begins with historical notes by J.P. Boris and D.L. Book who invented FCT in the early 1970s. The chapters that follow describe the design of fully multidimensional FCT algorithms for structured and unstructured grids, limiting for systems of conservation laws, and the use of FCT as an implicit subgrid scale model. The second edition presents 200 pages of additional material. The main highlights of the three new chapters include: FCT-constrained interpolation for Arbitrary Lagrangian-Eulerian methods, an optimization-based approach to flux correction, and FCT simulations of high-speed flows on overset grids. Addressing students and researchers, as well as CFD practitioners, the book is focused on computational aspects and contains m...
Energy Technology Data Exchange (ETDEWEB)
Schunk, Peter Randall; Cairncross, Richard A. (Drexel University, Philadelphia, PA); Madasu, S. (Drexel University, Philadelphia, PA)
2004-03-01
This report summarizes research advances pursued with award funding issued by the DOE to Drexel University through the Presidential Early Career Award (PECASE) program. Professor Rich Cairncross was the recipient of this award in 1997. With it he pursued two related research topics under Sandia's guidance that address the outstanding issue of fluid-structural interactions of liquids with deformable solid materials, focusing mainly on the ubiquitous dynamic wetting problem. The project focus in the first four years was aimed at deriving a predictive numerical modeling approach for the motion of the dynamic contact line on a deformable substrate. A formulation of physical model equations was derived in the context of the Galerkin finite element method in an arbitrary Lagrangian/Eulerian (ALE) frame of reference. The formulation was successfully integrated in Sandia's Goma finite element code and tested on several technologically important thin-film coating problems. The model equations, the finite-element implementation, and results from several applications are given in this report. In the last year of the five-year project the same physical concepts were extended towards the problem of capillary imbibition in deformable porous media. A synopsis of this preliminary modeling and experimental effort is also discussed.
Fluid-structure interaction analysis of the drop impact test for helicopter fuel tank.
Yang, Xianfeng; Zhang, Zhiqiang; Yang, Jialing; Sun, Yuxin
2016-01-01
The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid-structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian-Eulerian method was constructed to elucidate the dynamic failure behavior. The drop impact tests were conducted to validate the accuracy of the numerical simulation. Good agreement was achieved between the experimental and numerical results of the impact force with the ground. The influences of the impact velocity, the impact angle, the thickness of the fuel tank wall and the volume fraction of water on the dynamic responses of the dropped fuel tank were studied. The results indicated that the corner of the fuel tank is the most vulnerable location during the impact with ground. PMID:27652146
LES of Gas Exchange in IC Engines
Directory of Open Access Journals (Sweden)
Mittal V.
2013-10-01
Full Text Available As engine technologies become increasingly complex and engines are driven to new operating points, understanding transient phenomena is important to ensure reliable engine operation. Unlike Reynolds Averaged Navier-Stokes (RANS studies that only provide cycle-averaged information, Large Eddy Simulation (LES studies are capable of simulating cycle-to-cycle dynamics. In this work, a finite difference based structured methodology for LES of IC engines is presented. This structured approach allows for an efficient mesh generation process and provides potential for higher order numerical accuracy. An efficient parallel scalable block decomposition is done to overcome the challenges associated with the low ratio of fluid elements to overall mesh elements. The motion of the valves and piston is handled using a dynamic cell blanking approach and the Arbitrary Lagrangian Eulerian (ALE method, respectively. Modified three-dimensional Navier-Stokes Characteristic Boundary Conditions (NSCBC are used in the simulation to prescribe conditions in the manifolds. The accuracy of the simulation framework is validated using various canonical configurations. Flow bench simulations of an axisymmetric configuration and an actual engine geometry are done with the LES methodology. Simulations of the gas exchange in an engine under motored conditions are also performed. Overall, good agreement is obtained with experiments for all the cases. Therefore, this framework can be used for LES of engine simulations. In the future, reactive LES simulations will be performed using this framework.
Ebrahimi, Mohsen; Abbaspour, Madjid
2015-01-01
The hydrodynamics and energetics of bioinspired oscillating mechanisms have received significant attentions by engineers and biologists to develop the underwater and air vehicles. Undulating and pure heaving (or plunging) motions are two significant mechanisms which are utilized in nature to provide propulsive, maneuvering, and stabilization forces. This study aims to elucidate and compare the propulsive vortical signature and performance of these two important natural mechanisms through a systematic numerical study. Navier-Stokes equations are solved, by a pressure-based finite volume method solver, in an arbitrary Lagrangian-Eulerian (ALE) framework domain containing a 2D NACA0012 foil moving with prescribed kinematics. Some of the important findings are (1) the thrust production of the heaving foil begins at lower St and has a greater growing slope with respect to the St; (2) the undulating mechanism has some limitations to produce high thrust forces; (3) the undulating foil shows a lower power consumption and higher efficiency; (4) changing the Reynolds number (Re) in a constant St affects the performance of the oscillations; and (5) there is a distinguishable appearance of leading edge vortices in the wake of the heaving foil without observable ones in the wake of the undulating foil, especially at higher St.
Wollny, Ines; Hartung, Felix; Kaliske, Michael
2016-05-01
In order to gain a deeper knowledge of the interactions in the coupled tire-pavement-system, e.g. for the future design of durable pavement structures, the paper presents recent results of research in the field of theoretical-numerical asphalt pavement modeling at material and structural level, whereby the focus is on a realistic and numerically efficient computation of pavements under rolling tire load by using the finite element method based on an Arbitrary Lagrangian Eulerian (ALE) formulation. Inelastic material descriptions are included into the ALE frame efficiently by a recently developed unsplit history update procedure. New is also the implementation of a viscoelastic cohesive zone model into the ALE pavement formulation to describe the interaction of the single pavement layers. The viscoelastic cohesive zone model is further extended to account for the normal pressure dependent shear behavior of the bonding layer. Another novelty is that thermo-mechanical effects are taken into account by a coupling of the mechanical ALE pavement computation to a transient thermal computation of the pavement cross-section to obtain the varying temperature distributions of the pavement due to climatic impact. Then, each ALE pavement simulation considers the temperature dependent asphalt material model that includes elastic, viscous and plastic behavior at finite strains and the temperature dependent viscoelastic cohesive zone formulation. The temperature dependent material parameters of the asphalt layers and the interfacial layers are fitted to experimental data. Results of coupled tire-pavement computations are presented to demonstrate potential fields of application.
PIV validation of blood-heart valve leaflet interaction modelling.
Kaminsky, R; Dumont, K; Weber, H; Schroll, M; Verdonck, P
2007-07-01
The aim of this study was to validate the 2D computational fluid dynamics (CFD) results of a moving heart valve based on a fluid-structure interaction (FSI) algorithm with experimental measurements. Firstly, a pulsatile laminar flow through a monoleaflet valve model with a stiff leaflet was visualized by means of Particle Image Velocimetry (PIV). The inflow data sets were applied to a CFD simulation including blood-leaflet interaction. The measurement section with a fixed leaflet was enclosed into a standard mock loop in series with a Harvard Apparatus Pulsatile Blood Pump, a compliance chamber and a reservoir. Standard 2D PIV measurements were made at a frequency of 60 bpm. Average velocity magnitude results of 36 phase-locked measurements were evaluated at every 10 degrees of the pump cycle. For the CFD flow simulation, a commercially available package from Fluent Inc. was used in combination with inhouse developed FSI code based on the Arbitrary Lagrangian-Eulerian (ALE) method. Then the CFD code was applied to the leaflet to quantify the shear stress on it. Generally, the CFD results are in agreement with the PIV evaluated data in major flow regions, thereby validating the FSI simulation of a monoleaflet valve with a flexible leaflet. The applicability of the new CFD code for quantifying the shear stress on a flexible leaflet is thus demonstrated.
Spread of arbitrary conventions among chimpanzees: a controlled experiment.
Bonnie, Kristin E; Horner, Victoria; Whiten, Andrew; de Waal, Frans B M
2007-02-01
Wild chimpanzees (Pan troglodytes) have a rich cultural repertoire--traditions common in some communities are not present in others. The majority of reports describe functional, material traditions, such as tool use. Arbitrary conventions have received far less attention. In the same way that observations of material culture in wild apes led to experiments to confirm social transmission and identify underlying learning mechanisms, experiments investigating how arbitrary habits or conventions arise and spread within a group are also required. The few relevant experimental studies reported thus far have relied on cross-species (i.e. human-ape) interaction offering limited ecological validity, and no study has successfully generated a tradition not involving tool use in an established group. We seeded one of two rewarded alternative endpoints to a complex sequence of behaviour in each of two chimpanzee groups. Each sequence spread in the group in which it was seeded, with many individuals unambiguously adopting the sequence demonstrated by a group member. In one group, the alternative sequence was discovered by a low ranking female, but was not learned by others. Since the action-sequences lacked meaning before the experiment and had no logical connection with reward, chimpanzees must have extracted both the form and benefits of these sequences through observation of others. PMID:17164200
Acoustic quasi-lossless transmission in arbitrary pathway of network
Dai, Hongqing; Xia, Baizhan; Yu, Dejie
2016-01-01
Acoustic metamaterials have exhibited extraordinary possibilities to manipulate the propagation of the sound wave. Up to now, it is still a challenge to control the propagation of the sound wave in an arbitrary pathway of a network. Here, we design a symmetry breaking cross-shape metamaterial comprised of Helmholtz resonant cells and a square column. The square column is eccentrically arranged. The sound wave can quasi-lossless transmit through channels along the eccentric direction with compressed spaces, which breaks through the general transmission phenomenon. This exotic propagation characteristic is verified by the band structure and the mode of the metamaterial. Two acoustic networks, including a 2x2 network and an 8x8 network, show that the sound wave can quasi-lossless propagate along various arbitrary pathways, such as the Great Wall shape, the stair step shape and the serpentine shape, by reconfiguring eccentric directions. This ability opens up a new venue to route the sound wave and exhibits promi...
Ibañez, Diego Rodríguez; Gómez-Pedrero, José A; Alonso, Jose; Quiroga, Juan A
2016-03-21
A new method for fitting a series of Zernike polynomials to point clouds defined over connected domains of arbitrary shape defined within the unit circle is presented in this work. The method is based on the application of machine learning fitting techniques by constructing an extended training set in order to ensure the smooth variation of local curvature over the whole domain. Therefore this technique is best suited for fitting points corresponding to ophthalmic lenses surfaces, particularly progressive power ones, in non-regular domains. We have tested our method by fitting numerical and real surfaces reaching an accuracy of 1 micron in elevation and 0.1 D in local curvature in agreement with the customary tolerances in the ophthalmic manufacturing industry. PMID:27136788
Efficient and exact sampling of simple graphs with given arbitrary degree sequence
Del Genio, Charo I; Toroczkai, Zoltan; Bassler, Kevin E
2010-01-01
Uniform sampling from graphical realizations of a given degree sequence is a fundamental component in simulation-based measurements of network observables, with applications ranging from epidemics, through social networks to Internet modeling. Existing graph sampling methods are either link-swap based (Markov-Chain Monte Carlo algorithms) or stub-matching based (the Configuration Model). Both types are ill-controlled, with typically unknown mixing times for link-swap methods and uncontrolled rejections for the Configuration Model. Here we propose an efficient, polynomial time algorithm that generates statistically independent graph samples with a given, arbitrary, degree sequence. The algorithm provides a weight associated with each sample, allowing the observable to be measured either uniformly over the graph ensemble, or, alternatively, with a desired distribution. Unlike other algorithms, this method always produces a sample, without back-tracking or rejections. Using a central limit theorem-based reasonin...
Preparing arbitrary pure states of spatial qudits with a single phase-only spatial light modulator
Solís-Prosser, M A; Varga, J J M; Rebón, L; Ledesma, S; Iemmi, C; Neves, L
2013-01-01
Spatial qudits are D-dimensional ($D\\geq 2$) quantum systems carrying information encoded in the discretized transverse momentum and position of single photons. We present a proof-of-principle demonstration of a method for preparing arbitrary pure states of such systems by using a single phase-only spatial light modulator (SLM). The method relies on the encoding of the complex transmission function corresponding to a given spatial qudit state onto a preset diffraction order of a phase-only grating function addressed at the SLM. Fidelities of preparation above 94% were obtained with this method, which is simpler, less costly, and more efficient than those that require two SLMs for the same purpose.
Directory of Open Access Journals (Sweden)
Benjamin Fredembach
Full Text Available BACKGROUND: It is well-known that human beings are able to associate stimuli (novel or not perceived in their environment. For example, this ability is used by children in reading acquisition when arbitrary associations between visual and auditory stimuli must be learned. The studies tend to consider it as an "implicit" process triggered by the learning of letter/sound correspondences. The study described in this paper examined whether the addition of the visuo-haptic exploration would help adults to learn more effectively the arbitrary association between visual and auditory novel stimuli. METHODOLOGY/PRINCIPAL FINDINGS: Adults were asked to learn 15 new arbitrary associations between visual stimuli and their corresponding sounds using two learning methods which differed according to the perceptual modalities involved in the exploration of the visual stimuli. Adults used their visual modality in the "classic" learning method and both their visual and haptic modalities in the "multisensory" learning one. After both learning methods, participants showed a similar above-chance ability to recognize the visual and auditory stimuli and the audio-visual associations. However, the ability to recognize the visual-auditory associations was better after the multisensory method than after the classic one. CONCLUSION/SIGNIFICANCE: This study revealed that adults learned more efficiently the arbitrary association between visual and auditory novel stimuli when the visual stimuli were explored with both vision and touch. The results are discussed from the perspective of how they relate to the functional differences of the manual haptic modality and the hypothesis of a "haptic bond" between visual and auditory stimuli.
Inverted Gabor holography principle for tailoring arbitrary shaped three-dimensional beams
Latychevskaia, Tatiana; Fink, Hans-Werner
2016-05-01
It is well known that by modifying the wavefront in a certain manner, the light intensity can be turned into a certain shape. However, all known light modulation techniques allow for limited light modifications only: focusing within a restricted region in space, shaping into a certain class of parametric curves along the optical axis or bending described by a quadratic-dependent deflection as in the case of Airy beams. We show a general case of classical light wavefront shaping that allows for intensity and phase redistribution into an arbitrary profile including pre-determined switching-off of the intensity. To create an arbitrary three-dimensional path of intensity, we represent the path as a sequence of closely packed individual point-like absorbers and simulate the in-line hologram of the created object set; when such a hologram is contrast inverted, thus giving rise to a diffractor, it creates the pre-determined three-dimensional path of intensity behind the diffractor under illumination. The crucial parameter for a smooth optical path is the sampling of the predetermined curves, which is given by the lateral and axial resolution of the optical system. We provide both, simulated and experimental results to demonstrate the power of this novel method.
Energy Technology Data Exchange (ETDEWEB)
Man, Zhong-Xiao, E-mail: zxman@mail.qfnu.edu.cn [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); An, Nguyen Ba, E-mail: nban@iop.vast.ac.vn [Center for Theoretical Physics, Institute of Physics, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); Xia, Yun-Jie, E-mail: yjxia@mail.qfnu.edu.cn [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); Kim, Jaewan, E-mail: jaewan@kias.re.kr [School of Computational Sciences, Korea Institute for Advanced Study, Hoegiro 85, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of)
2014-12-15
In combination with the theories of open system and quantum recovering measurement, we propose a quantum state transfer scheme using spin chains by performing two sequential operations: a projective measurement on the spins of ‘environment’ followed by suitably designed quantum recovering measurements on the spins of interest. The scheme allows perfect transfer of arbitrary multispin states through multiple parallel spin chains with finite probability. Our scheme is universal in the sense that it is state-independent and applicable to any model possessing spin–spin interactions. We also present possible methods to implement the required measurements taking into account the current experimental technologies. As applications, we consider two typical models for which the probabilities of perfect state transfer are found to be reasonably high at optimally chosen moments during the time evolution. - Highlights: • Scheme that can achieve perfect quantum state transfer is devised. • The scheme is state-independent and applicable to any spin-interaction models. • The scheme allows perfect transfer of arbitrary multispin states. • Applications to two typical models are considered in detail.
Magnetohydrodynamic effects on a charged colloidal sphere with arbitrary double-layer thickness.
Hsieh, Tzu H; Keh, Huan J
2010-10-01
An analytical study is presented for the magnetohydrodynamic (MHD) effects on a translating and rotating colloidal sphere in an arbitrary electrolyte solution prescribed with a general flow field and a uniform magnetic field at a steady state. The electric double layer surrounding the charged particle may have an arbitrary thickness relative to the particle radius. Through the use of a simple perturbation method, the Stokes equations modified with an electric force term, including the Lorentz force contribution, are dealt by using a generalized reciprocal theorem. Using the equilibrium double-layer potential distribution from solving the linearized Poisson-Boltzmann equation, we obtain closed-form formulas for the translational and angular velocities of the spherical particle induced by the MHD effects to the leading order. It is found that the MHD effects on the particle movement associated with the translation and rotation of the particle and the ambient fluid are monotonically increasing functions of κa, where κ is the Debye screening parameter and a is the particle radius. Any pure rotational Stokes flow of the electrolyte solution in the presence of the magnetic field exerts no MHD effect on the particle directly in the case of a very thick double layer (κa→0). The MHD effect caused by the pure straining flow of the electrolyte solution can drive the particle to rotate, but it makes no contribution to the translation of the particle.
Institute of Scientific and Technical Information of China (English)
徐志杰
2012-01-01
We present a rigorous homogenization approach for elcient computation of a class of physical problems in a one-dimensional periodic heterogeneous material. This material is represented by a spatially periodic array of unit cells with a length of More specifically, the method is applied to the diffusion, heat conduction, and wave propagation problems. Heterogeneous materials can have arbitrary position-dependent continuous or discontinuous materials properties （for example heat conductivity） within the unit cell. The final effective model includes both effective properties at the leading order and high-order contributions due to the microscopic heterogeneity. A dimensionless heterogeneity parameter ~ is defined to represent high-order contributions, shown to be in the range of [-1/12, 0], and has a universal expression for all three problems. Both effective properties and heterogeneity parameter 13 are independent oft, the microscopic scale of heterogeneity. The homogenized solution describing macroscopic variations can be obtained from the effective model. Solution with sub-unit-cell accuracy can be constructed based on the homogenized solution and its spatial derivatives. The paper represents a general approach to obtain the effective model for arbitrary periodic heterogeneous materials with position-dependent properties.
Moteki, Nobuhiro
2016-07-01
An accurate and efficient simulation of light scattering by an atmospheric black carbon (BC)-containing aerosol-a fractal-like cluster of hundreds of carbon monomers that is internally mixed with other aerosol compounds such as sulfates, organics, and water-remains challenging owing to the enormous diversities of such aerosols' size, shape, and mixing state. Although the discrete dipole approximation (DDA) is theoretically an exact numerical method that is applicable to arbitrary non-spherical inhomogeneous targets, in practice, it suffers from severe granularity-induced error and degradation of computational efficiency for such extremely complex targets. To solve this drawback, we propose herein a hybrid DDA method designed for arbitrary BC-containing aerosols: the monomer-dipole assumption is applied to a cluster of carbon monomers, whereas the efficient cubic-lattice discretization is applied to the remaining particle volume consisting of other materials. The hybrid DDA is free from the error induced by the surface granularity of carbon monomers that occurs in conventional cubic-lattice DDA. In the hybrid DDA, we successfully mitigate the artifact of neglecting the higher-order multipoles in the monomer-dipole assumption by incorporating the magnetic dipole in addition to the electric dipole into our DDA formulations. Our numerical experiments show that the hybrid DDA method is an efficient light-scattering solver for BC-containing aerosols in arbitrary mixing states. The hybrid DDA could be also useful for a cluster of metallic nanospheres associated with other dielectric materials.
Ma, Yanyuan
2013-09-01
We propose semiparametric methods to estimate the center and shape of a symmetric population when a representative sample of the population is unavailable due to selection bias. We allow an arbitrary sample selection mechanism determined by the data collection procedure, and we do not impose any parametric form on the population distribution. Under this general framework, we construct a family of consistent estimators of the center that is robust to population model misspecification, and we identify the efficient member that reaches the minimum possible estimation variance. The asymptotic properties and finite sample performance of the estimation and inference procedures are illustrated through theoretical analysis and simulations. A data example is also provided to illustrate the usefulness of the methods in practice. © 2013 American Statistical Association.
Maric, Tomislav; Bothe, Dieter
2013-01-01
A new parallelized unsplit geometrical Volume of Fluid (VoF) algorithm with support for arbitrary unstructured meshes and dynamic local Adaptive Mesh Refinement (AMR), as well as for two and three dimensional computation is developed. The geometrical VoF algorithm supports arbitrary unstructured meshes in order to enable computations involving flow domains of arbitrary geometrical complexity. The implementation of the method is done within the framework of the OpenFOAM library for Computational Continuum Mechanics (CCM) using the C++ programming language with modern policy based design for high program code modularity. The development of the geometrical VoF algorithm significantly extends the method base of the OpenFOAM library by geometrical volumetric flux computation for two-phase flow simulations. For the volume fraction advection, a novel unsplit geometrical algorithm is developed, which inherently sustains volume conservation utilizing unique Lagrangian discrete trajectories located in the mesh points. ...
Compound words prompt arbitrary semantic associations in conceptual memory
Boutonnet, Bastien; McClain, Rhonda; Thierry, Guillaume
2014-01-01
Linguistic relativity theory has received empirical support in domains such as color perception and object categorization. It is unknown, however, whether relations between words idiosyncratic to language impact non-verbal representations and conceptualizations. For instance, would one consider the concepts of horse and sea as related were it not for the existence of the compound seahorse? Here, we investigated such arbitrary conceptual relationships using a non-linguistic picture relatedness task in participants undergoing event-related brain potential recordings. Picture pairs arbitrarily related because of a compound and presented in the compound order elicited N400 amplitudes similar to unrelated pairs. Surprisingly, however, pictures presented in the reverse order (as in the sequence horse–sea) reduced N400 amplitudes significantly, demonstrating the existence of a link in memory between these two concepts otherwise unrelated. These results break new ground in the domain of linguistic relativity by revealing predicted semantic associations driven by lexical relations intrinsic to language. PMID:24672505
Generating Polarization-Entangled Photon Pairs with Arbitrary Joint Spectrum
Walton, Z D; Saleh, B E A; Teich, M C; Walton, Zachary D.; Sergienko, Alexander V.; Saleh, Bahaa E. A.; Teich, Malvin C.
2004-01-01
We present a scheme for generating polarization-entangled photons pairs with arbitrary joint spectrum. Specifically, we describe a technique for spontaneous parametric down-conversion in which both the center frequencies and the bandwidths of the down-converted photons may be controlled by appropriate manipulation of the pump pulse. The spectral control offered by this technique permits one to choose the operating wavelengths for each photon of a pair based on optimizations of other system parameters (loss in optical fiber, photon counter performance, etc.). The combination of spectral control, polarization control, and lack of group-velocity matching conditions makes this technique particularly well-suited for a distributed quantum information processing architecture in which integrated optical circuits are connected by spans of optical fiber.
Stimulator with arbitrary waveform for auditory evoked potentials
Energy Technology Data Exchange (ETDEWEB)
Martins, H R; Romao, M; Placido, D; Provenzano, F; Tierra-Criollo, C J [Universidade Federal de Minas Gerais (UFMG), Departamento de Engenharia Eletrica (DEE), Nucleo de Estudos e Pesquisa em Engenharia Biomedica NEPEB, Av. Ant. Carlos, 6627, sala 2206, Pampulha, Belo Horizonte, MG, 31.270-901 (Brazil)
2007-11-15
The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential.
Faithful teleportation with arbitrary pure or mixed resource states
International Nuclear Information System (INIS)
We study faithful teleportation systematically with arbitrary entangled states as resources. The necessary conditions of mixed states to complete perfect teleportation are proved. Based on these results, the necessary and sufficient conditions of faithful teleportation of an unknown state |φ) in Cd with an entangled resource ρ in Cm otimes Cd and Cd otimes Cn are derived. It is shown that for ρ in Cm otimes Cd, ρ must be a maximally entangled state, while for ρ in Cd otimes Cn, ρ must be a pure maximally entangled state. Moreover, we show that the sender's measurements must be all projectors of maximally entangled pure states. The relations between the entanglement of the formation of the resource states and faithful teleportation are also discussed.
Faithful teleportation with arbitrary pure or mixed resource states
Energy Technology Data Exchange (ETDEWEB)
Zhao Mingjing; Fei Shaoming; Wang Zhixi [School of Mathematical Sciences, Capital Normal University, Beijing 100048 (China); Li Zongguo [College of Science, Tianjin University of Technology, Tianjin 300191 (China); Lijost Xianqing, E-mail: zhaomingjingde@126.com [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig (Germany)
2011-05-27
We study faithful teleportation systematically with arbitrary entangled states as resources. The necessary conditions of mixed states to complete perfect teleportation are proved. Based on these results, the necessary and sufficient conditions of faithful teleportation of an unknown state |{phi}) in C{sup d} with an entangled resource {rho} in C{sup m} otimes C{sup d} and C{sup d} otimes C{sup n} are derived. It is shown that for {rho} in C{sup m} otimes C{sup d}, {rho} must be a maximally entangled state, while for {rho} in C{sup d} otimes C{sup n}, {rho} must be a pure maximally entangled state. Moreover, we show that the sender's measurements must be all projectors of maximally entangled pure states. The relations between the entanglement of the formation of the resource states and faithful teleportation are also discussed.
Supersymmetric N=2 gauge theory with arbitrary gauge group
Kuchiev, Michael
2009-01-01
A universal model, which implements the Seiberg-Witten approach to low-energy properties of the supersymmetric N=2 gauge theory with an arbitrary compact simple gauge group, classical or exceptional, is suggested. It has a clear form based on the hyperelliptic curve, whose genus equals the rank of the gauge group. The weak and strong coupling limits are reproduced correctly. The magnetic and electric charges of light dyons, which are present in the proposed model at strong coupling comply with recent predictions derived from the general properties of N=2 and N=1 gauge theories. The discrete chiral symmetry is implemented, the duality condition is reproduced, and connections between monodromies at weak and strong coupling are established. The model predicts the identical analytic structure of the coupling constants for the theories based on the SU(r+1) and Sp(2r) gauge groups.
Apodized Pupil Lyot Coronagraphs for Arbitrary Telescope Apertures
Soummer, R
2004-01-01
In the context of high dynamic range imaging, this study presents a breakthrough for the understanding of Apodized Pupil Lyot Coronagraphs, making them available for arbitrary aperture shapes. These new solutions find immediate application in current, ground-based coronagraphic studies (Gemini, VLT) and in existing instruments (AEOS Lyot Project). They also offer the possiblity of a search for an on-axis design for TPF. The unobstructed aperture case has already been solved by Aime et al. (2002) and Soummer et al. (2003). Analytical solutions with identical properties exist in the general case and, in particular, for centrally obscured apertures. Chromatic effects can be mitigated with a numerical optimization. The combination of analytical and numerical solutions enables the study of the complete parameter space (central obstruction, apodization throughput, mask size, bandwidth, and Lyot stop size).
New representation of orbital motion with arbitrary angular momenta
Suzuki, Y; Varga, K
1997-01-01
A new formulation is presented for a variational calculation of $N$-body systems on a correlated Gaussian basis with arbitrary angular momenta. The rotational motion of the system is described with a single spherical harmonic of the total angular momentum $L$, and thereby needs no explicit coupling of partial waves between particles. A simple generating function for the correlated Gaussian is exploited to derive the matrix elements. The formulation is applied to various Coulomb three-body systems such as $e^-e^-e^+, tt\\mu, td\\mu$, and $\\alpha e^-e^-$ up to $L=4$ in order to show its usefulness and versatility. A stochastic selection of the basis functions gives good results for various angular momentum states.
Classical resolution of black hole singularities in arbitrary dimension
Bazeia, D; Olmo, Gonzalo J; Rubiera-Garcia, D; Sanchez-Puente, A
2015-01-01
A metric-affine approach is employed to study higher-dimensional modified gravity theories involving different powers and contractions of the Ricci tensor. It is shown that the field equations are \\emph{always} second-order, as opposed to the standard metric approach, where this is only achieved for Lagrangians of the Lovelock type. We point out that this property might have relevant implications for the AdS/CFT correspondence in black hole scenarios. We illustrate these aspects by considering the case of Born-Infeld gravity in $d$ dimensions, where we work out exact solutions for electrovacuum configurations. Our results put forward that black hole singularities in arbitrary dimensions can be cured in a purely classical geometric scenario governed by second-order field equations.
Universal Quantum Computing with Arbitrary Continuous-Variable Encoding
Lau, Hoi-Kwan; Plenio, Martin B.
2016-09-01
Implementing a qubit quantum computer in continuous-variable systems conventionally requires the engineering of specific interactions according to the encoding basis states. In this work, we present a unified formalism to conduct universal quantum computation with a fixed set of operations but arbitrary encoding. By storing a qubit in the parity of two or four qumodes, all computing processes can be implemented by basis state preparations, continuous-variable exponential-swap operations, and swap tests. Our formalism inherits the advantages that the quantum information is decoupled from collective noise, and logical qubits with different encodings can be brought to interact without decoding. We also propose a possible implementation of the required operations by using interactions that are available in a variety of continuous-variable systems. Our work separates the "hardware" problem of engineering quantum-computing-universal interactions, from the "software" problem of designing encodings for specific purposes. The development of quantum computer architecture could hence be simplified.
Single-mode squeezing in arbitrary spatial modes
Semmler, Marion; Chille, Vanessa; Gabriel, Christian; Banzer, Peter; Aiello, Andrea; Marquardt, Christoph; Leuchs, Gerd
2016-01-01
As the generation of squeezed states of light has become a standard technique in laboratories, attention is increasingly directed towards adapting the optical parameters of squeezed beams to the specific requirements of individual applications. It is known that imaging, metrology, and quantum information may benefit from using squeezed light with a tailored transverse spatial mode. However, experiments have so far been limited to generating only a few squeezed spatial modes within a given setup. Here, we present the generation of single-mode squeezing in Laguerre-Gauss and Bessel-Gauss modes, as well as an arbitrary intensity pattern, all from a single setup using a spatial light modulator (SLM). The degree of squeezing obtained is limited mainly by the initial squeezing and diffractive losses introduced by the SLM, while no excess noise from the SLM is detectable at the measured sideband. The experiment illustrates the single-mode concept in quantum optics and demonstrates the viability of current SLMs as fl...
Growing Multiplex Networks with Arbitrary Number of Layers
Fotouhi, Babak
2015-01-01
This paper focuses on the problem of growing multiplex networks. Currently, the results on the inter-layer degree distribution of growing multiplex networks present in the literature pertain to the case of two layers, and are confined to the special case of homogeneous growth. In the present paper, we obtain closed-form solutions for the inter-layer degree distribution of heterogeneously growing multilayer networks with arbitrary number of layers in the steady state. Heterogeneous growth means that each incoming node establishes different numbers of links in different layers. We first briefly consider the problem for two layers: we consider the cases of preferential attachment and uniform attachment separately, and we obtain closed-form expressions for the inter-layer degree distribution and expected degree distributions in each layer. Then for both attachment schemes, we generalize the problem to $M$ layers, and provide solutions for the joint degree distribution across all layers.
Compound words prompt arbitrary semantic associations in conceptual memory
Directory of Open Access Journals (Sweden)
Bastien eBoutonnet
2014-03-01
Full Text Available Linguistic relativity theory has received empirical support in domains such as colour perception and object categorisation. It is unknown however, whether relations between words idiosyncratic to language impact nonverbal representations and conceptualisations. For instance, would one consider the concepts of horse and sea as related were it not for the existence of the compound seahorse? Here, we investigated such arbitrary conceptual relationships using a non-linguistic picture relatedness task in participants undergoing event-related brain potential recordings. Picture pairs arbitrarily related because of a compound and presented in the compound order elicited N400 amplitudes similar to unrelated pairs. Surprisingly, however, pictures presented in the reverse order (as in the sequence horse – sea reduced N400 amplitudes significantly, demonstrating the existence of a link in memory between these two concepts otherwise unrelated. These results break new ground in the domain of linguistic relativity by revealing predicted semantic associations driven by lexical relations intrinsic to language.
Calculating fusion neutron energy spectra from arbitrary reactant distributions
Eriksson, J.; Conroy, S.; Andersson Sundén, E.; Hellesen, C.
2016-02-01
The Directional Relativistic Spectrum Simulator (DRESS) code can perform Monte-Carlo calculations of reaction product spectra from arbitrary reactant distributions, using fully relativistic kinematics. The code is set up to calculate energy spectra from neutrons and alpha particles produced in the D(d, n)3He and T(d, n)4He fusion reactions, but any two-body reaction can be simulated by including the corresponding cross section. The code has been thoroughly tested. The kinematics calculations have been benchmarked against the kinematics module of the ROOT Data Analysis Framework. Calculated neutron energy spectra have been validated against tabulated fusion reactivities and against an exact analytical expression for the thermonuclear fusion neutron spectrum, with good agreement. The DRESS code will be used as the core of a detailed synthetic diagnostic framework for neutron measurements at the JET and MAST tokamaks.
Binary Neutron Stars with Arbitrary Spins in Numerical Relativity
Tacik, Nick; Pfeiffer, Harald P; Haas, Roland; Ossokine, Serguei; Kaplan, Jeff; Muhlberger, Curran; Duez, Matt D; Kidder, Lawrence E; Scheel, Mark A; Szilágyi, Béla
2015-01-01
We present a code to construct initial data for binary neutron star systems in which the stars are rotating. Our code, based on a formalism developed by Tichy, allows for arbitrary rotation axes of the neutron stars and is able to achieve rotation rates near rotational breakup. We compute the neutron star angular momentum through quasi-local angular momentum integrals. When constructing irrotational binary neutron stars, we find a very small residual dimensionless spin of $\\sim 2\\times 10^{-4}$. Evolutions of rotating neutron star binaries show that the magnitude of the stars' angular momentum is conserved, and that the spin- and orbit-precession of the stars is well described by post-Newtonian approximation. We demonstrate that orbital eccentricity of the binary neutron stars can be controlled to $\\sim 0.1\\%$. The neutron stars show quasi-normal mode oscillations at an amplitude which increases with the rotation rate of the stars.
Forced fluid dynamics from gravity in arbitrary dimensions
International Nuclear Information System (INIS)
We consider long wavelength solutions to the Einstein-dilaton system with negative cosmological constant which are dual, under the AdS/CFT correspondence, to solutions of the conformal relativistic Navier-Stokes equations with a dilaton-dependent forcing term. Certain forced fluid flows are known to exhibit turbulence; holographic duals of forced fluid dynamics are therefore of particular interest as they may aid efforts towards an explicit model of holographic steady state turbulence. In recent work, Bhattacharyya et al. have constructed long wavelength asymptotically locally AdS5 bulk spacetimes with a slowly varying boundary dilaton field which are dual to forced fluid flows on the 4−dimensional boundary. In this paper, we generalise their work to arbitrary spacetime dimensions; we explicitly compute the dual bulk metric, the fluid dynamical stress tensor and Lagrangian to second order in a boundary derivative expansion
Three-loop vacuum integrals with arbitrary masses
Freitas, Ayres
2016-01-01
Three-loop vacuum integrals are an important building block for the calculation of a wide range of three-loop corrections. Until now, only results for integrals with one and two independent mass scales are known, but in the electroweak Standard Model and many extensions thereof, one often encounters more mass scales of comparable magnitude. For this reason, a numerical approach for the evaluation of three-loop vacuum integrals with arbitrary mass pattern is proposed here. Concretely, one can identify a basic set of three master integral topologies. With the help of dispersion relations, each of these can be transformed into one-dimensional or, for the most complicated case, two-dimensional integrals in terms of elementary functions, which are suitable for efficient numerical integration.
Multitarget sensor resolution model for arbitrary target numbers
Svensson, Daniel; Ulmke, Martin; Danielsson, Lars
2010-04-01
In many surveillance problems the observed objects are so closely spaced that they cannot always be resolved by the sensor(s). Typical examples for partially unresolved measurements are the surveillance of aircraft in formation, and convoy tracking for ground surveillance. Ignoring the limited sensor resolution in a tracking system may lead to degraded tracking performance, in particular unwanted track-losses. In this paper we extend the resolution model by Koch and van Keuk, given for two partially unresolved objects, to the case of arbitrary object numbers. We also derive the effects of the resolution model to the multi-target likelihood function and the possible data associations. Further, it is shown how the model can be integrated into the Joint Probabilistic Data Association Filter (JPDAF).
Universal Quantum Computing with Arbitrary Continuous-Variable Encoding.
Lau, Hoi-Kwan; Plenio, Martin B
2016-09-01
Implementing a qubit quantum computer in continuous-variable systems conventionally requires the engineering of specific interactions according to the encoding basis states. In this work, we present a unified formalism to conduct universal quantum computation with a fixed set of operations but arbitrary encoding. By storing a qubit in the parity of two or four qumodes, all computing processes can be implemented by basis state preparations, continuous-variable exponential-swap operations, and swap tests. Our formalism inherits the advantages that the quantum information is decoupled from collective noise, and logical qubits with different encodings can be brought to interact without decoding. We also propose a possible implementation of the required operations by using interactions that are available in a variety of continuous-variable systems. Our work separates the "hardware" problem of engineering quantum-computing-universal interactions, from the "software" problem of designing encodings for specific purposes. The development of quantum computer architecture could hence be simplified.
Electron with arbitrary pseudo-spins in multilayer graphene
Institute of Scientific and Technical Information of China (English)
Worasak Prarokijjak; Bumned Soodchomshom
2015-01-01
Using the low-energy effective Hamiltonian of the ABC-stacked multilayer graphene, the pseudo-spin coupling to real orbital angular momentum of electrons in multilayer graphene is investigated. We show that the electron wave function in N-layer graphene mimics the behavior of a particle with a spin of N × (}/2), where N={1, 2, 3, . . .}. It is said that for N>1 the low-energy effective Hamiltonian for ABC-stacked graphene cannot be used to describe pseudo-spin-1/2 particles. The wave function of electrons in multilayer graphene may behave like fermionic (or bosonic) particle for N being odd (or even). In this paper, we propose a theory of graphene serving as a host material of electrons with arbitrary pseudo-spins tunable by changing the number of graphene layers.
Universal sequence map (USM of arbitrary discrete sequences
Directory of Open Access Journals (Sweden)
Almeida Jonas S
2002-02-01
Full Text Available Abstract Background For over a decade the idea of representing biological sequences in a continuous coordinate space has maintained its appeal but not been fully realized. The basic idea is that any sequence of symbols may define trajectories in the continuous space conserving all its statistical properties. Ideally, such a representation would allow scale independent sequence analysis – without the context of fixed memory length. A simple example would consist on being able to infer the homology between two sequences solely by comparing the coordinates of any two homologous units. Results We have successfully identified such an iterative function for bijective mappingψ of discrete sequences into objects of continuous state space that enable scale-independent sequence analysis. The technique, named Universal Sequence Mapping (USM, is applicable to sequences with an arbitrary length and arbitrary number of unique units and generates a representation where map distance estimates sequence similarity. The novel USM procedure is based on earlier work by these and other authors on the properties of Chaos Game Representation (CGR. The latter enables the representation of 4 unit type sequences (like DNA as an order free Markov Chain transition table. The properties of USM are illustrated with test data and can be verified for other data by using the accompanying web-based tool:http://bioinformatics.musc.edu/~jonas/usm/. Conclusions USM is shown to enable a statistical mechanics approach to sequence analysis. The scale independent representation frees sequence analysis from the need to assume a memory length in the investigation of syntactic rules.
Institute of Scientific and Technical Information of China (English)
LIN Jian-guo; XIE Zhi-hua; ZHOU Jun-tao
2007-01-01
Based on the successive iteration in the Taylor series expansion method, a three-point explicit compact difference scheme with arbitrary order of accuracy is derived in this paper. Numerical characteristics of the scheme are studied by the Fourier analysis.Unlike the conventional compact difference schemes which need to solve the equation to obtain the unknown derivatives in each node, the proposed scheme is explicit and can achieve arbitrary order of accuracy in space. Application examples for the convectiondiffusion problem with a sharp front gradient and the typical lid-driven cavity flow are given. It is found that the proposed compact scheme is not only simple to implement and economical to use, but also is effective to simulate the convection-dominated problem and obtain high-order accurate solution in coarse grid systems.
Developing a Learning Algorithm-Generated Empirical Relaxer
Energy Technology Data Exchange (ETDEWEB)
Mitchell, Wayne [Univ. of Colorado, Boulder, CO (United States). Dept. of Applied Math; Kallman, Josh [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Toreja, Allen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gallagher, Brian [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jiang, Ming [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Laney, Dan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-03-30
One of the main difficulties when running Arbitrary Lagrangian-Eulerian (ALE) simulations is determining how much to relax the mesh during the Eulerian step. This determination is currently made by the user on a simulation-by-simulation basis. We present a Learning Algorithm-Generated Empirical Relaxer (LAGER) which uses a regressive random forest algorithm to automate this decision process. We also demonstrate that LAGER successfully relaxes a variety of test problems, maintains simulation accuracy, and has the potential to significantly decrease both the person-hours and computational hours needed to run a successful ALE simulation.
Periodic Boundary Conditions in the ALEGRA Finite Element Code
Energy Technology Data Exchange (ETDEWEB)
AIDUN,JOHN B.; ROBINSON,ALLEN C.; WEATHERBY,JOE R.
1999-11-01
This document describes the implementation of periodic boundary conditions in the ALEGRA finite element code. ALEGRA is an arbitrary Lagrangian-Eulerian multi-physics code with both explicit and implicit numerical algorithms. The periodic boundary implementation requires a consistent set of boundary input sets which are used to describe virtual periodic regions. The implementation is noninvasive to the majority of the ALEGRA coding and is based on the distributed memory parallel framework in ALEGRA. The technique involves extending the ghost element concept for interprocessor boundary communications in ALEGRA to additionally support on- and off-processor periodic boundary communications. The user interface, algorithmic details and sample computations are given.
Energy Technology Data Exchange (ETDEWEB)
Knap, J; McClelland, M A; Maienschein, J L; Howard, W M; Nichols, A L; deHaven, M R; Strand, O T
2006-06-22
We describe the results of a Scaled-Thermal-Explosion-eXperiment (STEX) for LX-10 (94.7 % HMX, 5.3 % Viton A) confined in an AerMet 100 (iron-cobalt-nickel alloy) tube with reinforced end caps. The experimental measurements are compared with predictions of an Arbitrary-Lagrangian-Eulerian (ALE3D) computer model. ALE3D is a three-dimensional multi-physics computer code capable of solving coupled equations describing thermal, mechanical and chemical behavior of materials. In particular, we focus on the processes linked to fracture and fragmentation of the AerMet tube driven by the LX-10 deflagration.
Flapping hydrofoil performance at low Reynolds numbers
Energy Technology Data Exchange (ETDEWEB)
Pedro, G.; Suleman, A.; Djilali, N. [Univ. of Victoria, Dept. of Mechanical Engineering, Victoria, British Columbia (Canada)]. E-mail: gpedro@uvic.ca; suleman@uvic.ca; ndjilali@uvic.ca
2003-07-01
This paper relates the study of unsteady flow past oscillating hydrofoils at low Reynolds numbers using a computational fluid dynamics research code based on structured grids. The solver utilizes an explicit, time-stepping algorithm with an Arbitrary Lagrangian-Eulerian formulation to account for mesh movement. The viscous flow past a NACA0012 hydrofoil at various pitching and heaving frequencies and other design parameters is simulated. The effect of these parameters on thrust, power and efficiency is studied along with flow field visualisations to account for these variations. (author)
Meshing Highly Regular Structures: The Case of Super Carbon Nanotubes of Arbitrary Order
Directory of Open Access Journals (Sweden)
Christian Schröppel
2015-01-01
Full Text Available Mesh generation is an important step in many numerical methods. We present the “Hierarchical Graph Meshing” (HGM method as a novel approach to mesh generation, based on algebraic graph theory. The HGM method can be used to systematically construct configurations exhibiting multiple hierarchies and complex symmetry characteristics. The hierarchical description of structures provided by the HGM method can be exploited to increase the efficiency of multiscale and multigrid methods. In this paper, the HGM method is employed for the systematic construction of super carbon nanotubes of arbitrary order, which present a pertinent example of structurally and geometrically complex, yet highly regular, structures. The HGM algorithm is computationally efficient and exhibits good scaling characteristics. In particular, it scales linearly for super carbon nanotube structures and is working much faster than geometry-based methods employing neighborhood search algorithms. Its modular character makes it conducive to automatization. For the generation of a mesh, the information about the geometry of the structure in a given configuration is added in a way that relates geometric symmetries to structural symmetries. The intrinsically hierarchic description of the resulting mesh greatly reduces the effort of determining mesh hierarchies for multigrid and multiscale applications and helps to exploit symmetry-related methods in the mechanical analysis of complex structures.
Zhao, Chao; Yang, Guo-wu; Li, Xiao-yu
2016-09-01
Nowadays, there are plenty of separability criteria which are used to detect entanglement. Many of them are limited to apply for some cases. In this paper, we propose a separability criterion for arbitrary multipartite pure state which is based on the rank of reduced density matrix. It is proved that the rank of reduced density matrices of a multipartite state is closely related to entanglement. In fact it can be used to characterize entanglement. Our separability criterion is a necessary and sufficient condition for detecting entanglement. Furthermore, it is able to help us find the completely separable form of a multipartite pure state according to some explicit examples. Finally it demonstrates that our method are more suitable for some specific case. Our separability criterion are simple to understand and it is operational.
Incremental deformation analysis of shell and corrugated diaphragm based on arbitrary configuration
Institute of Scientific and Technical Information of China (English)
Xuefeng He; Jue Zhang; Huijun Chen; Jing Fang
2005-01-01
With respect to an arbitrary configuration of a deformed structure, two sets of incremental equations are proposed for the deformation analysis of revolution shells and diaphragms loaded by both lateral pressures and the initial stresses produced in manufacturing. These general equations can be reduced to the simplified Koiter's Reissner-Meissner-Reissner (RMR) equations and the simplified Reissner's equations, when the initial stresses are set to zero.They can also be deduced to the total Lagrange form or the updated Lagrange form, respectively, as the structure is specified as the un-deformed or the former-deformed configurations. These incremental equations can be easily transformed into finite difference forms and solved by common numerical solvers of ordinary differential equations. Some numerical examples are presented to show the applications of the incremental equations to the deep shell of revolution and the corrugated diaphragms used in microelectronical mechanical system (MEMS). The results are in good agreement with those from finite element method (FEM).
Polarizabilities of an annular cut in the wall of an arbitrary thickness
Kurennoy, S. S.
1996-07-01
The electric and magnetic polarizabilities of an aperture are its important characteristics in the theory of aperture coupling and diffraction of EM waves. The beam coupling impedances due to a small discontinuity on the chamber wall of an accelerator can also be expressed in terms of the polarizabilities of the discontinuity. The polarizabilities are geometrical factors which can be found by solving a static (electric or magnetic) problem. However, they are known in an explicit analytical form only for a few simple-shaped discontinuities, such as an elliptic hole in a thin wall. In the present paper the polarizabilities of a ring-shaped cut in the wall of an arbitrary thickness are studied using a combination of analytical, variational and numerical methods. The results are applied to estimate the coupling impedances of button-type beam position monitors.
Polarizabilities of an annular cut in the wall of an arbitrary thickness
Kurennoy, S S
1995-01-01
The electric and magnetic polarizabilities of an aperture are its important characteristics in the theory of aperture coupling and diffraction of EM waves. The beam coupling impedances due to a small discontinuity on the chamber wall of an accelerator can also be expressed in terms of the polarizabilities of the discontinuity. The polarizabilities are geometrical factors which can be found by solving a static (electric or magnetic) problem. However, they are known in an explicit analytical form only for a few simple-shaped discontinuities, such as an elliptic hole in a thin wall. In the present paper the polarizabilities of a ring-shaped cut in the wall of an arbitrary thickness are studied using a combination of analytical, variational and numerical methods. The results are applied to estimate the coupling impedances of button-type beam position monitors.
Garrido, M C; Ruiz, A; 10.1613/jair.533
2011-01-01
This paper presents a general and efficient framework for probabilistic inference and learning from arbitrary uncertain information. It exploits the calculation properties of finite mixture models, conjugate families and factorization. Both the joint probability density of the variables and the likelihood function of the (objective or subjective) observation are approximated by a special mixture model, in such a way that any desired conditional distribution can be directly obtained without numerical integration. We have developed an extended version of the expectation maximization (EM) algorithm to estimate the parameters of mixture models from uncertain training examples (indirect observations). As a consequence, any piece of exact or uncertain information about both input and output values is consistently handled in the inference and learning stages. This ability, extremely useful in certain situations, is not found in most alternative methods. The proposed framework is formally justified from standard prob...
A mesh partitioning algorithm for preserving spatial locality in arbitrary geometries
Nivarti, Girish V.; Salehi, M. Mahdi; Bushe, W. Kendal
2015-01-01
A space-filling curve (SFC) is a proximity preserving linear mapping of any multi-dimensional space and is widely used as a clustering tool. Equi-sized partitioning of an SFC ignores the loss in clustering quality that occurs due to inaccuracies in the mapping. Often, this results in poor locality within partitions, especially for the conceptually simple, Morton order curves. We present a heuristic that improves partition locality in arbitrary geometries by slicing a Morton order curve at points where spatial locality is sacrificed. In addition, we develop algorithms that evenly distribute points to the extent possible while maintaining spatial locality. A metric is defined to estimate relative inter-partition contact as an indicator of communication in parallel computing architectures. Domain partitioning tests have been conducted on geometries relevant to turbulent reactive flow simulations. The results obtained highlight the performance of our method as an unsupervised and computationally inexpensive domain partitioning tool.
Magneto-optical response in the arbitrary-Chern number topological phase on square lattice
Wang, Yi-Xiang
2016-07-01
In this work, we investigate the magneto-optical response in the arbitrary-Chern number topological phase. Based on the Dirac theory, we derive the analytic expressions for the magneto-optical response. More importantly, we construct the model on the possible square lattice and make the numerical calculations with the exact diagonalization method. We find the analytical and numerical results are in good agreement with each other. For the optical absorption spectrum, the low-energy absorptive peaks and the corresponding hopping processes are distinct in different Chern number phases, heavily depending on the filling factor of the system. While for the optical Hall conductivities, the physical mechanisms are revealed for the dichroism of the absorption peaks in response to the right- and left-circularly polarized light. We discuss the feasibility of these results in experiment.
Althaus, Ernst; Caprara, Alberto; Lenhof, Hans-Peter; Reinert, Knut
2002-01-01
Multiple sequence alignment is one of the dominant problems in computational molecular biology. Numerous scoring functions and methods have been proposed, most of which result in NP-hard problems. In this paper we propose for the first time a general formulation for multiple alignment with arbitrary gap-costs based on an integer linear program (ILP). In addition we describe a branch-and-cut algorithm to effectively solve the ILP to optimality. We evaluate the performances of our approach in terms of running time and quality of the alignments using the BAliBase database of reference alignments. The results show that our implementation ranks amongst the best programs developed so far.
Coupling dynamic analysis of a liquid-filled spherical container subject to arbitrary excitation
Institute of Scientific and Technical Information of China (English)
Jing Lü; Shimin Wang; Tianshu Wang
2012-01-01
Using spherical coordinates,the coupling nonlinear dynamic system of a liquid-filled spherical tank,which can be excited discretionarily,is deduced by the H-O variational principle,and the viscous damping is introduced via the liquid dissipation function.The kinetic equations of the coupling system are deduced by the relationship between the velocity of liquid particles and the disturbed liquid surface equation.Normal differential equations are obtained through the Galerkin method.An equivalent mechanical model is developed for liquid sloshing in a spherical tank subject to arbitrary excitation.The fixed and slosh masses,as well as the spring and damping constants,are determined in such a way as to satisfy the principle of equivalence.Numerical simula tions illustrate the theoretical results in this paper as well.
Institute of Scientific and Technical Information of China (English)
Giuseppe Grassi
2013-01-01
Referring to continuous-time chaotic systems,this paper presents a new projective synchronization scheme,which enables each drive system state to be synchronized with a linear combination of response system states for any arbitrary scaling matrix.The proposed method,based on a structural condition related to the uncontrollable eigenvalues of the error system,can be applied to a wide class of continuous-time chaotic (hyperchaotic) systems and represents a general framework that includes any type of synchronization defined to date.An example involving a hyperchaotic oscillator is reported,with the aim of showing how a response system attractor is arbitrarily shaped using a scalar synchronizing signal only.Finally,it is shown that the recently introduced dislocated synchronization can be readily achieved using the conceived scheme.
Efficient transfer of an arbitrary qutrit state in circuit quantum electrodynamics.
Liu, Tong; Xiong, Shao-Jie; Cao, Xiao-Zhi; Su, Qi-Ping; Yang, Chui-Ping
2015-12-01
Compared with a qubit, a qutrit (i.e., three-level quantum system) has a larger Hilbert space and thus can be used to encode more information in quantum information processing and communication. Here, we propose a method to transfer an arbitrary quantum state between two flux qutrits coupled to two resonators. This scheme is simple because it only requires two basic operations. The state-transfer operation can be performed fast because only resonant interactions are used. Numerical simulations show that the high-fidelity transfer of quantum states between the two qutrits is feasible with current circuit-QED technology. This scheme is quite general and can be applied to accomplish the same task for other solid-state qutrits coupled to resonators.
International Nuclear Information System (INIS)
A very general calculational strategy is applied to the evaluation of the divergent physical amplitudes which are typical of perturbative calculations. With this approach in the final results all the intrinsic arbitrariness of the calculations due to the divergent character is still present. We show that by using the symmetry properties as a guide to search for the (compulsory) choices in such a way as to avoid ambiguities, a deep and clear understanding of the role of regularization methods emerges. Requiring then a universal point of view for the problem, as allowed by our approach, very interesting conclusions can be stated about the possible justifications of the most intriguing aspect of perturbative calculations in quantum field theory: the triangle anomalies
Solving the Helmholtz equation for membranes of arbitrary shape: numerical results
Energy Technology Data Exchange (ETDEWEB)
Amore, Paolo [Facultad de Ciencias CUICBAS, Universidad de Colima, Bernal DIaz del Castillo 340, Colima, Colima (Mexico); Physics Department, University of Texas at El Paso, El Paso, TX (United States)], E-mail: paolo.amore@gmail.google.com
2008-07-04
I calculate the modes of vibration of membranes of arbitrary shape using a collocation approach based on little sinc functions. The matrix representation of the PDE obtained using this method is explicit and does not require the calculation of integrals. To illustrate the virtues of this approach, I have considered a large number of examples, part of them are taken from the literature, and part of them new. When possible, I have tested the accuracy of these results by comparing them with the exact results (when available) or with results from the literature. In particular, in the case of the L-shaped membrane, the first example discussed in the paper, I show that it is possible to extrapolate the results obtained with different grid sizes to obtain highly precise results. Finally, I also show that the present collocation technique can be easily combined with conformal mapping to provide numerical approximations to the energies which quite rapidly converge to the exact results.
Beam distortion of rotation double prisms with an arbitrary incident angle.
Li, Anhu; Zuo, Qiyou; Sun, Wansong; Yi, Wanli
2016-07-01
The distortion of beam shape in rotation Risley prisms is discussed in this paper. Using the ray-tracing method based on vector refraction theorem, a rigorous theoretical model of beam distortion with an arbitrary incident angle is established to explore the influencing factors. For a specified double-prism pair, the emergent beam is squeezed in one direction while stretched in the mutual perpendicular direction, the distortion of which is determined by the relative rotation angle. Moreover, the distortion of beam shape is greatly influenced by the wedge angles and the refractive indices of the prisms, as well as different double-prism configurations, while uncorrelated to the prism thickness and the distance between two prisms. This paper demonstrates the regular change of the beam shape with multiparameter variations in rotation double prisms, which can be applied to the design of rotation double-prism systems. PMID:27409205
Institute of Scientific and Technical Information of China (English)
Wang Teng; Wang Kuihua; Xie Kanghe
2001-01-01
The vibration problem of a pile of arbitrary segments with variable modulus under exciting force is established, in which the influence of the soil under pile toe and the surroundings is taken into account. With Laplace transforms, the transmit functions for velocity and displacement of pile are derived. Furthermore, in terms of the convolution theorem and inversed Laplace transform, an analytical solution for the time domain response of a pile subjected to a semi-sine impulse is developed,which is the theoretical basis of the sonic method in pile integrity testing. Based on the solution, the vibration properties of pile with sharp or continuous modulus are studied. The validity of this approach is verified through fidd dynamic tests on some engineering piles. It shows that the theoretical prediction and the response of the pile are in good agreement.
Efficient transfer of an arbitrary qutrit state in circuit quantum electrodynamics.
Liu, Tong; Xiong, Shao-Jie; Cao, Xiao-Zhi; Su, Qi-Ping; Yang, Chui-Ping
2015-12-01
Compared with a qubit, a qutrit (i.e., three-level quantum system) has a larger Hilbert space and thus can be used to encode more information in quantum information processing and communication. Here, we propose a method to transfer an arbitrary quantum state between two flux qutrits coupled to two resonators. This scheme is simple because it only requires two basic operations. The state-transfer operation can be performed fast because only resonant interactions are used. Numerical simulations show that the high-fidelity transfer of quantum states between the two qutrits is feasible with current circuit-QED technology. This scheme is quite general and can be applied to accomplish the same task for other solid-state qutrits coupled to resonators. PMID:26625061
MESHII, Toshiyuki; WATANABE, Katsuhiko
2001-01-01
This paper presents the development of a practical method, by using prepared tabulated data, tocalculate the mode I stress intensity factor (SIF) for an inner surface circumferential crack in a finitelength cylinder. The crack surfaces are subjected to an axisymmetric stress with an arbitrary biquadraticradial distribution. The method was derived by applying the authors’ weight function for the crack. Thiswork is based on the thin shell theory and the Petroski-Achenbach method. Our method is ...
International Nuclear Information System (INIS)
We present the bound state solution of Schrödinger equation in D dimensions for quadratic exponential-type potential for arbitrary l-state. We use generalized parametric Nikiforov–Uvarov method to obtain the energy levels and the corresponding eigenfunction in closed form. We also compute the energy eigenvalues numerically
Displaying CFD Solution Parameters on Arbitrary Cut Planes
Pao, S. Paul
2008-01-01
USMC6 is a Fortran 90 computer program for post-processing in support of visualization of flows simulated by computational fluid dynamics (CFD). The name "USMC6" is partly an abbreviation of "TetrUSS - USM3D Solution Cutter," reflecting its origin as a post-processor for use with USM3D - a CFD program that is a component of the Tetrahedral Unstructured Software System and that solves the Navier-Stokes equations on tetrahedral unstructured grids. "Cutter" here refers to a capability to acquire and process solution data on (1) arbitrary planes that cut through grid volumes, or (2) user-selected spheroidal, conical, cylindrical, and/or prismatic domains cut from within grids. Cutting saves time by enabling concentration of post-processing and visualization efforts on smaller solution domains of interest. The user can select from among more than 40 flow functions. The cut planes can be trimmed to circular or rectangular shape. The user specifies cuts and functions in a free-format input file using simple and easy-to-remember keywords. The USMC6 command line is simple enough that the slicing process can readily be embedded in a shell script for assembly-line post-processing. The output of USMC6 is a data file ready for plotting.
The Casimir effect for fields with arbitrary spin
Energy Technology Data Exchange (ETDEWEB)
Stokes, Adam; Bennett, Robert, E-mail: r.bennett@leeds.ac.uk
2015-09-15
The Casimir force arises when a quantum field is confined between objects that apply boundary conditions to it. In a recent paper we used the two-spinor calculus to derive boundary conditions applicable to fields with arbitrary spin in the presence of perfectly reflecting surfaces. Here we use these general boundary conditions to investigate the Casimir force between two parallel perfectly reflecting plates for fields up to spin-2. We use the two-spinor calculus formalism to present a unified calculation of well-known results for spin-1/2 (Dirac) and spin-1 (Maxwell) fields. We then use our unified framework to derive new results for the spin-3/2 and spin-2 fields, which turn out to be the same as those for spin-1/2 and spin-1. This is part of a broader conclusion that there are only two different Casimir forces for perfectly reflecting plates—one associated with fermions and the other with bosons.
Dirac equation for particles with arbitrary half-integral spin
Guseinov, I. I.
2011-11-01
The sets of ? -component irreducible and Clifford algebraic Hermitian and unitary matrices through the two-component Pauli matrices are suggested, where s = 1/2, 3/2, 5/2, … . Using these matrix sets, the eigenvalues of which are ? , the ? -component generalized Dirac equation for a description of arbitrary half-integral spin particles is constructed. In accordance with the correspondence principle, the generalized Dirac equation suggested arises from the condition of relativistic invariance. This equation is reduced to the sets of two-component matrix equations the number of which is equal to ? . The new relativistic invariant equation of motion leads to an equation of continuity with a positive-definite probability density and also to the Klein-Gordon equation. This relativistic equation is causal in the presence of an external electromagnetic field interaction. It is shown that, in the case of nonrelativistic limit, the relativistic equation presented is reduced to the Pauli equation describing the motion of half-integral spin particle in the electromagnetic field.
Holographic Flavor Transport in Arbitrary Constant Background Fields
Ammon, Martin; O'Bannon, Andy
2009-01-01
We use gauge-gravity duality to compute a new transport coefficient associated with a number Nf of massive N=2 supersymmetric hypermultiplet fields propagating through an N=4 SU(Nc) super-Yang-Mills theory plasma in the limits of large Nc and large 't Hooft coupling, with Nf << Nc. We introduce a baryon number density as well as arbitrary constant electric and magnetic fields, generalizing previous calculations by including a magnetic field with a component parallel to the electric field. We can thus compute all components of the conductivity tensor associated with transport of baryon number charge, including a component never before calculated in gauge-gravity duality. We also compute the contribution that the flavor degrees of freedom make to the stress-energy tensor, which exhibits divergences associated with the rates of energy and momentum loss of the flavor degrees of freedom. We discuss two currents that are free from these divergences, one of which becomes anomalous when the magnetic field has a...
Astrometry.net: Blind Astrometric Calibration of Arbitrary Astronomical Images
Lang, Dustin; Hogg, David W.; Mierle, Keir; Blanton, Michael; Roweis, Sam
2010-05-01
We have built a reliable and robust system that takes as input an astronomical image, and returns as output the pointing, scale, and orientation of that image (the astrometric calibration or World Coordinate System information). The system requires no first guess, and works with the information in the image pixels alone; that is, the problem is a generalization of the "lost in space" problem in which nothing—not even the image scale—is known. After robust source detection is performed in the input image, asterisms (sets of four or five stars) are geometrically hashed and compared to pre-indexed hashes to generate hypotheses about the astrometric calibration. A hypothesis is only accepted as true if it passes a Bayesian decision theory test against a null hypothesis. With indices built from the USNO-B catalog and designed for uniformity of coverage and redundancy, the success rate is >99.9% for contemporary near-ultraviolet and visual imaging survey data, with no false positives. The failure rate is consistent with the incompleteness of the USNO-B catalog; augmentation with indices built from the Two Micron All Sky Survey catalog brings the completeness to 100% with no false positives. We are using this system to generate consistent and standards-compliant meta-data for digital and digitized imaging from plate repositories, automated observatories, individual scientific investigators, and hobbyists. This is the first step in a program of making it possible to trust calibration meta-data for astronomical data of arbitrary provenance.
Dynamical deformed Airy beams with arbitrary angles between two wings.
Liang, Yi; Hu, Yi; Ye, Zhuoyi; Song, Daohong; Lou, Cibo; Zhang, Xinzheng; Xu, Jingjun; Morandotti, Roberto; Chen, Zhigang
2014-07-01
We study both numerically and experimentally the acceleration and propagation dynamics of 2D Airy beams with arbitrary initial angles between their "two wings." Our results show that the acceleration of these generalized 2D Airy beams strongly depends on the initial angles and cannot be simply described by the vector superposition principle (except for the normal case of a 90° angle). However, as a result of the "Hyperbolic umbilic" catastrophe (a two-layer caustic), the main lobes of these 2D Airy beams still propagate along parabolic trajectories even though they become highly deformed. Under such conditions, the peak intensity (leading energy flow) of the 2D Airy beams cannot be confined along the main lobe, in contrast to the normal 90° case. Instead, it is found that there are two parabolic trajectories describing the beam propagation: one for the main lobe, and the other for the peak intensity. Both trajectories can be readily controlled by varying the initial wing angle. Due to their self-healing property, these beams tend to evolve into the well-known 1D or 2D Airy patterns after a certain propagation distance. The theoretical analysis corroborates our experimental observations, and explains clearly why the acceleration of deformed Airy beams increases with the opening of the initial wing angle. PMID:25121433
Analytical solutions for elastic binary nanotubes of arbitrary chirality
Jiang, Lai; Guo, Wanlin
2016-09-01
Analytical solutions for the elastic properties of a variety of binary nanotubes with arbitrary chirality are obtained through the study of systematic molecular mechanics. This molecular mechanics model is first extended to chiral binary nanotubes by introducing an additional out-of-plane inversion term into the so-called stick-spiral model, which results from the polar bonds and the buckling of binary graphitic crystals. The closed-form expressions for the longitudinal and circumferential Young's modulus and Poisson's ratio of chiral binary nanotubes are derived as functions of the tube diameter. The obtained inversion force constants are negative for all types of binary nanotubes, and the predicted tube stiffness is lower than that by the former stick-spiral model without consideration of the inversion term, reflecting the softening effect of the buckling on the elastic properties of binary nanotubes. The obtained properties are shown to be comparable to available density functional theory calculated results and to be chirality and size sensitive. The developed model and explicit solutions provide a systematic understanding of the mechanical performance of binary nanotubes consisting of III-V and II-VI group elements.