Ionic solutions of two-dimensional materials
Cullen, Patrick L.; Cox, Kathleen M.; Bin Subhan, Mohammed K.; Picco, Loren; Payton, Oliver D.; Buckley, David J.; Miller, Thomas S.; Hodge, Stephen A.; Skipper, Neal T.; Tileli, Vasiliki; Howard, Christopher A.
2016-11-01
Strategies for forming liquid dispersions of nanomaterials typically focus on retarding reaggregation, for example via surface modification, as opposed to promoting the thermodynamically driven dissolution common for molecule-sized species. Here we demonstrate the true dissolution of a wide range of important 2D nanomaterials by forming layered material salts that spontaneously dissolve in polar solvents yielding ionic solutions. The benign dissolution advantageously maintains the morphology of the starting material, is stable against reaggregation and can achieve solutions containing exclusively individualized monolayers. Importantly, the charge on the anionic nanosheet solutes is reversible, enables targeted deposition over large areas via electroplating and can initiate novel self-assembly upon drying. Our findings thus reveal a unique solution-like behaviour for 2D materials that enables their scalable production and controlled manipulation.
Institute of Scientific and Technical Information of China (English)
XU Quan; TIAN Qiang
2009-01-01
We restrict our attention to the discrete two-dimensional monatomic β-FPU lattice. We look for twodimensional breather lattice solutions and two-dimensional compact-like discrete breathers by using trying method and analyze their stability by using Aubry's linearly stable theory. We obtain the conditions of existence and stability of two-dimensional breather lattice solutions and two-dimensional compact-like discrete breathers in the discrete twodimensional monatomic β-FPU lattice.
Two-Dimensional Rectangular Stock Cutting Problem and Solution Methods
Institute of Scientific and Technical Information of China (English)
Zhao Hui; Yu Liang; Ning Tao; Xi Ping
2001-01-01
Optimal layout of rectangular stock cutting is still in great demand from industry for diversified applications. This paper introduces four basic solution methods to the problem: linear programming, dynamic programming, tree search and heuristic approach. A prototype of application software is developed to verify the pros and cons of various approaches.
Efficient solution of two-dimensional steady separated flows
Napolitano, M.
This work is concerned with the numerical solution of 2D incompressible steady laminar separated flows at moderate-to-high values of Re. The vorticity-stream function Navier-Stokes equations, as well as approximate models based upon the boundary-layer theory, will be considered. The main objective of the paper is to present the development of an efficient approach for solving a class of problems usually referred to as high Re weakly separated flows. A description is given of a block-alternating-direction-implicit method, which applies the approximate factorization scheme of Beam and Warming to the vorticity-stream function equations, using the delta form of the deferred correction procedure of Khosla and Rubin to combine the stability of upwind schemes with the accuracy of central differences. The logical steps which led to the development of a more efficient incremental block-line Gauss-Seidel method and to a simple multigrid strategy particularly suited for this kind of numerical scheme are then outlined. Finally, benchmark-quality solutions for separated flows inside diffusers and channels with smooth as well as sudden expansions are presented.
Two-dimensional thermoelasticity solution for functionally graded thick beams
Institute of Scientific and Technical Information of China (English)
Lü; Chaofeng
2006-01-01
[1]Suresh S,Mortensen A.Fundamentals of Functionally Graded Materials.London:IOM Communications,1998[2]Wetherhold R C,Seelman S,Wang J Z.The use of functionally graded materials to eliminate or control thermal deformation.Compos Sci Technol,1996,56:1099―1104[3]Almajid A,Taya M,Hudnut S.Analysis of out-of-plane displacement and stress field in a piezo-composite plate with functionally graded microstructure.Int J Solids Struct,2001,38:3377―3391[4]Wu X H,Chen C Q,Shen Y P,et al.A high order theory for functionally graded piezoelectric shells.Int J Solids Struct,2002,39:5325―5344[5]Ootao Y,Tanigawa Y.Three-dimensional transient piezothermo-elasticity in functional graded rectangular plate bonded to a piezoelectric plate.Int J Solids Struct,2000,37:4377―4401[6]Chen W Q,Ding H J.On free vibration of a functionally graded piezoelectric rectangular plate.Acta Mech,2002,153:207―216[7]Chen W Q,Bian Z G,Lv C F,et al.3D free vibration analysis of a functionally graded piezoelectric hollow cylinder filled with compressible fluid.Int J Solids Struct,2004,41:947―964[8]Zhong Z,Shang E T.Exact analysis of simply supported functionally graded piezothermoelectric plates.J Intell Mater Syst Struct,2005,16:643―651[9]Sankar B V.An elasticity solution for functionally graded beams.Compos Sci Technol,2001,61:689―696[10]Sankar B V,Tzeng J T.Thermal stresses in functionally graded beams.AIAA J,2002,40:1228―1232[11]Zhu H,Sankar B V.A combined Fourier series-Galerkin method for the analysis of functionally graded beams.J Appl Mech-Trans ASME,2004,71:421―424[12]Chen W Q,Lv C F,Bian Z G.Elasticity solution for free vibration of laminated beams.Compos Struct,2003,62:75―82[13]Nagem R J,Williams J H.Dynamic analysis of large space structures using transfer matrices and joint coupling matrices.Mech Struct Mach,1989,17:349―371[14]Ding H J,Chen W Q,Zhang L C.Elasticity of Transversely Isotropic Materials.Dordrecht:Springer-Verlag,2006[15]Shu C.Differential Quadrature and Its
Khare, Avinash; Samuelsen, Mogens R; Saxena, Avadh; 10.1088/1751-8113/43/37/375209
2010-01-01
We show that the two-dimensional, nonlinear Schr\\"odinger lattice with a saturable nonlinearity admits periodic and pulse-like exact solutions. We establish the general formalism for the stability considerations of these solutions and give examples of stability diagrams. Finally, we show that the effective Peierls-Nabarro barrier for the pulse-like soliton solution is zero.
DEFF Research Database (Denmark)
Khare, A.; Rasmussen, K. O.; Samuelsen, Mogens Rugholm
2010-01-01
We show that the two-dimensional, nonlinear Schrodinger lattice with a saturable nonlinearity admits periodic and pulse-like exact solutions. We establish the general formalism for the stability considerations of these solutions and give examples of stability diagrams. Finally, we show that the e......We show that the two-dimensional, nonlinear Schrodinger lattice with a saturable nonlinearity admits periodic and pulse-like exact solutions. We establish the general formalism for the stability considerations of these solutions and give examples of stability diagrams. Finally, we show...
Institute of Scientific and Technical Information of China (English)
XIONG Lei; LI haijiao; ZHANG Lewen
2008-01-01
The fourth-order B spline wavelet scaling functions are used to solve the two-dimensional unsteady diffusion equation. The calculations from a case history indicate that the method provides high accuracy and the computational efficiency is enhanced due to the small matrix derived from this method.The respective features of 3-spline wavelet scaling functions, 4-spline wavelet scaling functions and quasi-wavelet used to solve the two-dimensional unsteady diffusion equation are compared. The proposed method has potential applications in many fields including marine science.
Evaporative cooling of reactive polar molecules confined in a two-dimensional geometry
Zhu, Bihui; Rey, Ana M; Holland, Murray J
2013-01-01
Recent experimental developments in the loading of ultracold KRb molecules into quasi-two-dimensional traps, combined with the ability to tune the ratio between elastic and loss (inelastic/reactive) collisions through application of an external electric field, are opening the door to achieving efficient evaporative cooling of reactive polar molecules. In this paper, we use Monte Carlo simulations and semianalytic models to study theoretically the experimental parameter regimes in which evaporative cooling is feasible under current trapping conditions. We investigate the effect of the anisotropic character of dipole-dipole collisions and reduced dimensionality on evaporative cooling. We also present an analysis of the experimentally relevant anti-evaporation effects that are induced by chemical reactions that take place when more than one axial vibrational state is populated.
Analytic Solution for Two-Dimensional Heat Equation for an Ellipse Region
Directory of Open Access Journals (Sweden)
Nurcan Baykus Savasaneril
2016-01-01
Full Text Available In this study, an altenative method is presented for the solution of two-dimensional heat equation in an ellipse region. In this method, the solution function of the problem is based on the Green, and therefore on elliptic functions. To do this, it is made use of the basic consepts associated with elliptic integrals, conformal mappings and Green functions.
Soliton solutions of the two-dimensional KdV-Burgers equation by homotopy perturbation method
Energy Technology Data Exchange (ETDEWEB)
Molabahrami, A. [Department of Mathematics, Ilam University, PO Box 69315516, Ilam (Iran, Islamic Republic of)], E-mail: a_m_bahrami@yahoo.com; Khani, F. [Department of Mathematics, Ilam University, PO Box 69315516, Ilam (Iran, Islamic Republic of); Bakhtar Institute of Higher Education, PO Box 696, Ilam (Iran, Islamic Republic of)], E-mail: farzad_khani59@yahoo.com; Hamedi-Nezhad, S. [Bakhtar Institute of Higher Education, PO Box 696, Ilam (Iran, Islamic Republic of)
2007-10-29
In this Letter, the He's homotopy perturbation method (HPM) to finding the soliton solutions of the two-dimensional Korteweg-de Vries Burgers' equation (tdKdVB) for the initial conditions was applied. Numerical solutions of the equation were obtained. The obtained solutions, in comparison with the exact solutions admit a remarkable accuracy. The results reveal that the HPM is very effective and simple.
Exact solutions and conservation laws of the system of two-dimensional viscous Burgers equations
Abdulwahhab, Muhammad Alim
2016-10-01
Fluid turbulence is one of the phenomena that has been studied extensively for many decades. Due to its huge practical importance in fluid dynamics, various models have been developed to capture both the indispensable physical quality and the mathematical structure of turbulent fluid flow. Among the prominent equations used for gaining in-depth insight of fluid turbulence is the two-dimensional Burgers equations. Its solutions have been studied by researchers through various methods, most of which are numerical. Being a simplified form of the two-dimensional Navier-Stokes equations and its wide range of applicability in various fields of science and engineering, development of computationally efficient methods for the solution of the two-dimensional Burgers equations is still an active field of research. In this study, Lie symmetry method is used to perform detailed analysis on the system of two-dimensional Burgers equations. Optimal system of one-dimensional subalgebras up to conjugacy is derived and used to obtain distinct exact solutions. These solutions not only help in understanding the physical effects of the model problem but also, can serve as benchmarks for constructing algorithms and validation of numerical solutions of the system of Burgers equations under consideration at finite Reynolds numbers. Independent and nontrivial conserved vectors are also constructed.
Regularity of Stagnation Point-form Solutions of the Two-dimensional Euler Equations
Sarria, Alejandro
2013-01-01
A class of semi-bounded solutions of the two-dimensional incompressible Euler equations, satisfying either periodic or Dirichlet boundary conditions, is examined. For smooth initial data, new blowup criteria in terms of the initial concavity profile is presented and the effects that the boundary conditions have on the global regularity of solutions is discussed. In particular, by deriving a formula for a general solution along Lagrangian trajectories, we describe how p...
Inflation Cosmological Solutions in Two-Dimensional Brans-Dicke Gravity Model
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The purpose of this paper is to study cosmological properties of two-dimensional Brans-Dicke gravity model. For massless scalar field, the new cosmological solutions are found by integration of field equation, these solutions correspond to the inflation solutions with positive cosmological constant. The result of this paper show that the inflation process of universe is controlled by the classical and quantum effect of the scalar field.
Directory of Open Access Journals (Sweden)
Taha Aziz
2013-01-01
Full Text Available The simplest equation method is employed to construct some new exact closed-form solutions of the general Prandtl's boundary layer equation for two-dimensional flow with vanishing or uniform mainstream velocity. We obtain solutions for the case when the simplest equation is the Bernoulli equation or the Riccati equation. Prandtl's boundary layer equation arises in the study of various physical models of fluid dynamics. Thus finding the exact solutions of this equation is of great importance and interest.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper we investigate the two-dimensional compressible isentropic Euler equations for Chaplygin gases. Under the assumption that the initial data is close to a constant state and the vorticity of the initial velocity vanishes, we prove the global existence of the smooth solution to the Cauchy problem for twodimensional flow of Chaplygin gases.
EXISTENCE AND UNIQUENESS OF WEAK SOLUTIONS FOR TWO-DIMENSIONAL MODIFIED NAVIER-STOKES EQUATIONS
Institute of Scientific and Technical Information of China (English)
赵才地
2004-01-01
This paper studies a two-dimensional modified Navier-stokes equations. The author shows the existence and uniqueness of weak solutions for this equation by Galerkin method in bounded domains. The result is further extended to the case of unbounded channel-like domains.
Generalized scale-invariant solutions to the two-dimensional stationary Navier-Stokes equations
Guillod, Julien
2014-01-01
New explicit solutions to the incompressible Navier-Stokes equations in $\\mathbb{R}^{2}\\setminus\\left\\{ \\boldsymbol{0}\\right\\}$ are determined, which generalize the scale-invariant solutions found by Hamel. These new solutions are invariant under a particular combination of the scaling and rotational symmetries. They are the only solutions invariant under this new symmetry in the same way as the Hamel solutions are the only scale-invariant solutions. While the Hamel solutions are parameterized by a discrete parameter $n$, the flux $\\Phi$ and an angle $\\theta_{0}$, the new solutions generalize the Hamel solutions by introducing an additional parameter $a$ which produces a rotation. The new solutions decay like $\\left|\\boldsymbol{x}\\right|^{-1}$ as the Hamel solutions, and exhibit spiral behavior. The new variety of asymptotes induced by the existence of these solutions further emphasizes the difficulties faced when trying to establish the asymptotic behavior of the Navier-Stokes equations in a two-dimensional ...
A Numerical Solution of the Two-Dimensional Fusion Problem with Convective Boundary Conditions
Gülkaç, Vildan
2010-01-01
In this paper, we present an LOD method for solving the two-dimensional fusion problem with convective boundary conditions. In this study, we extend our earlier work [1] on the solution of the two-dimensional fusion problem by considering a class of time-split finite-difference methods, namely locally one-dimensional (LOD) schemes. In addition, following the idea of Douglas [2, 3], a Douglas-like splitting scheme is presented. A stability analysis by Fourier series method (von Neumann stability) of the scheme is also investigated. Computational results obtained by the present method are in excellent agreement with the results reported previously by other research.
Crowdy, Darren
2015-06-01
A one parameter family of analytical solutions for the equilibrium shapes of two-dimensional charged conducting droplets on a substrate with 90° contact angle is presented. The solutions exhibit the tendency to dewet at the droplet centre as the electrostatic stress increases. Such electrostatic deformations are believed to underlie the recently observed stick-slip dynamics of nanodroplets on substrates. Our theoretical results complement a number of other recent analytical and numerical studies of this phenomenon.
Two-dimensional Green`s function Poisson solution appropriate for cylindrical-symmetry simulations
Energy Technology Data Exchange (ETDEWEB)
Riley, M.E.
1998-04-01
This report describes the numerical procedure used to implement the Green`s function method for solving the Poisson equation in two-dimensional (r,z) cylindrical coordinates. The procedure can determine the solution to a problem with any or all of the applied voltage boundary conditions, dielectric media, floating (insulated) conducting media, dielectric surface charging, and volumetric space charge. The numerical solution is reasonably fast, and the dimension of the linear problem to be solved is that of the number of elements needed to represent the surfaces, not the whole computational volume. The method of solution is useful in the simulation of plasma particle motion in the vicinity of complex surface structures as found in microelectronics plasma processing applications. This report is a stand-alone supplement to the previous Sandia Technical Report SAND98-0537 presenting the two-dimensional Cartesian Poisson solver.
Kuiper, Logan K
2016-01-01
An approximate solution to the two dimensional Navier Stokes equation with periodic boundary conditions is obtained by representing the x any y components of fluid velocity with complex Fourier basis vectors. The chosen space of basis vectors is finite to allow for numerical calculations, but of variable size. Comparisons of the resulting approximate solutions as they vary with the size of the chosen vector space allow for extrapolation to an infinite basis vector space. Results suggest that such a solution, with the full basis vector space and which would give the exact solution, would fail for certain initial velocity configurations when initial velocity and time t exceed certain limits.
Solution of the two- dimensional heat equation for a rectangular plate
Directory of Open Access Journals (Sweden)
Nurcan BAYKUŞ SAVAŞANERİL
2015-11-01
Full Text Available Laplace equation is a fundamental equation of applied mathematics. Important phenomena in engineering and physics, such as steady-state temperature distribution, electrostatic potential and fluid flow, are modeled by means of this equation. The Laplace equation which satisfies boundary values is known as the Dirichlet problem. The solutions to the Dirichlet problem form one of the most celebrated topics in the area of applied mathematics. In this study, a novel method is presented for the solution of two-dimensional heat equation for a rectangular plate. In this alternative method, the solution function of the problem is based on the Green function, and therefore on elliptic functions.
A two-dimensional Euler solution for an unbladed jet engine configuration
Stewart, Mark E. M.
1992-01-01
A two dimensional, nonaxisymmetric Euler solution in a geometry representative of a jet engine configuration without blades is presented. The domain, including internal and external flow, is covered with a multiblock grid. In order to construct this grid, a domain decomposition technique is used to subdivide the domain, and smooth grids are dimensioned and placed in each block. The Euler solution is verified by examining five theoretical properties. The result demonstrates techniques for performing numerical solutions in complex geometries and provides a foundation for complete engine throughflow calculations.
Directory of Open Access Journals (Sweden)
Sohrab Bazm
2016-02-01
Full Text Available In this study, the Bernoulli polynomials are used to obtain an approximate solution of a class of nonlinear two-dimensional integral equations. To this aim, the operational matrices of integration and the product for Bernoulli polynomials are derived and utilized to reduce the considered problem to a system of nonlinear algebraic equations. Some examples are presented to illustrate the efficiency and accuracy of the method.
Block copolymer micelle coronas as quasi-two-dimensional dilute or semidilute polymer solutions
DEFF Research Database (Denmark)
Svaneborg, C.; Pedersen, J.S.
2001-01-01
Chain-chain interactions in a corona of polymers tethered to a spherical core under good solvent conditions are studied using Monte Carlo simulations. The total scattering function of the corona as well as different partial contributions are sampled. By combining the different contributions...... in a self-consistent approach, it is demonstrated that the corona can be regarded as a quasi-two-dimensional polymer solution, with a concentration dependence analogous to that of an ordinary polymer solution. Scattering due to the corona profile and density fluctuation correlations are separated...
Exact two-body solutions and quantum defect theory of two-dimensional dipolar quantum gas
Jie, Jianwen; Qi, Ran
2016-10-01
In this paper, we provide the two-body exact solutions of the two-dimensional (2D) Schrödinger equation with isotropic +/- 1/{r}3 interactions. An analytic quantum defect theory is constructed based on these solutions and it is applied to investigate the scattering properties as well as two-body bound states of an ultracold polar molecules confined in a quasi-2D geometry. Interestingly, we find that for the attractive case, the scattering resonance happens simultaneously in all partial waves, which has not been observed in other systems. The effect of this feature on the scattering phase shift across such resonances is also illustrated.
Two-dimensional motion of unstable steps induced by flow in solution
Sato, Masahide
2011-01-01
By carrying out Monte Carlo simulation, we study step instabilities during crystal growth from solution. In previous studies [M. Sato. J. Phys. Soc. Jpn. 79 (2010) 064606; M. Sato, J. Cryst. Growth 318 (2011) 5; M. Sato. J. Phys. Soc. Jpn. 80 (2011) 024604], we used a one-dimensional model, so that we were unable to study another type of instability, step wandering. In this research, we use a two-dimensional model to study both step wandering and step bunching. When the flow of solutes is in ...
On the Classical Solutions of Two Dimensional Inviscid Rotating Shallow Water System
Cheng, Bin
2009-01-01
We prove global existence and asymptotic behavior of classical solutions for two dimensional inviscid Rotating Shallow Water system with small initial data subject to the zero-relative-vorticity constraint. One of the key steps is a reformulation of the problem into a symmetric quasilinear Klein-Gordon system, for which the global existence of classical solutions is then proved with combination of the vector field approach and the normal forms. We also probe the case of general initial data and reveal a lower bound for the lifespan that is almost inversely proportional to the size of the initial relative vorticity.
Analytical solutions of the two-dimensional Dirac equation for a topological channel intersection
Anglin, J. R.; Schulz, A.
2017-01-01
Numerical simulations in a tight-binding model have shown that an intersection of topologically protected one-dimensional chiral channels can function as a beam splitter for noninteracting fermions on a two-dimensional lattice [Qiao, Jung, and MacDonald, Nano Lett. 11, 3453 (2011), 10.1021/nl201941f; Qiao et al., Phys. Rev. Lett. 112, 206601 (2014), 10.1103/PhysRevLett.112.206601]. Here we confirm this result analytically in the corresponding continuum k .p model, by solving the associated two-dimensional Dirac equation, in the presence of a "checkerboard" potential that provides a right-angled intersection between two zero-line modes. The method by which we obtain our analytical solutions is systematic and potentially generalizable to similar problems involving intersections of one-dimensional systems.
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Using a polarization method, the scattering problem for a two-dimensional inclusion embedded in infinite piezoelectric/piezomagnetic matrices is investigated. To achieve the purpose, the polarization method for a two-dimensional piezoelectric/piezo-magnetic "comparison body" is formulated. For simple harmonic motion, kernel of the polarization method reduces to a 2-D time-harmonic Green's function, which is ob-tained using the Radon transform. The expression is further simplified under condi-tions of low frequency of the incident wave and small diameter of the inclusion. Some analytical expressions are obtained. The analytical solutions for generalized piezoelec-tric/piezomagnetic anisotropic composites are given followed by simplified results for piezoelectric composites. Based on the latter results, two numerical results are provided for an elliptical cylindrical inclusion in a PZT-5H-matrix, showing the effect of different factors including size, shape, material properties, and piezoelectricity on the scattering cross-section.
Computer model of two-dimensional solute transport and dispersion in ground water
Konikow, Leonard F.; Bredehoeft, J.D.
1978-01-01
This report presents a model that simulates solute transport in flowing ground water. The model is both general and flexible in that it can be applied to a wide range of problem types. It is applicable to one- or two-dimensional problems involving steady-state or transient flow. The model computes changes in concentration over time caused by the processes of convective transport, hydrodynamic dispersion, and mixing (or dilution) from fluid sources. The model assumes that the solute is non-reactive and that gradients of fluid density, viscosity, and temperature do not affect the velocity distribution. However, the aquifer may be heterogeneous and (or) anisotropic. The model couples the ground-water flow equation with the solute-transport equation. The digital computer program uses an alternating-direction implicit procedure to solve a finite-difference approximation to the ground-water flow equation, and it uses the method of characteristics to solve the solute-transport equation. The latter uses a particle- tracking procedure to represent convective transport and a two-step explicit procedure to solve a finite-difference equation that describes the effects of hydrodynamic dispersion, fluid sources and sinks, and divergence of velocity. This explicit procedure has several stability criteria, but the consequent time-step limitations are automatically determined by the program. The report includes a listing of the computer program, which is written in FORTRAN IV and contains about 2,000 lines. The model is based on a rectangular, block-centered, finite difference grid. It allows the specification of any number of injection or withdrawal wells and of spatially varying diffuse recharge or discharge, saturated thickness, transmissivity, boundary conditions, and initial heads and concentrations. The program also permits the designation of up to five nodes as observation points, for which a summary table of head and concentration versus time is printed at the end of the
Anti-periodic traveling wave solution to a forced two-dimensional generalized KdV-Burgers equation
Institute of Scientific and Technical Information of China (English)
TAN Junyu
2003-01-01
The anti-periodic traveling wave solutions to a forced two-dimensional generalized KdV-Burgers equation are studied.Some theorems concerning the boundness, existence and uniqueness of the solution to this equation are proved.
Exact Solutions of Two-dimensional and Tri-dimensional Consolidation Equations
Di Francesco, Romolo
2011-01-01
The exact solution of Terzaghi's consolidation equation has further highlighted the limits of this theory in the one-dimensional field as, like Taylor's approximate solution, it overestimates the decay times of the phenomenon; on the other hand, one only needs to think about the accumulation pattern of sedimentary-basin soils to understand how their internal structure fits in more with the model of transversely isotropic medium, so as to result in the development of two- and three-dimensional consolidation models. This is the reason why, using Terzaghi's theory and his exact solution as starting point, two-dimensional and three-dimensional consolidation equations have been proposed, in an attempt to find their corresponding exact solutions which constitute more reliable forecasting models. Lastly, results show how this phenomenon is predominantly influenced by the dimensions of the horizontal plane affected by soil consolidation and permeabilities that behave according to three coordinate axes.
Small global solutions to the damped two-dimensional Boussinesq equations
Adhikari, Dhanapati; Cao, Chongsheng; Wu, Jiahong; Xu, Xiaojing
The two-dimensional (2D) incompressible Euler equations have been thoroughly investigated and the resolution of the global (in time) existence and uniqueness issue is currently in a satisfactory status. In contrast, the global regularity problem concerning the 2D inviscid Boussinesq equations remains widely open. In an attempt to understand this problem, we examine the damped 2D Boussinesq equations and study how damping affects the regularity of solutions. Since the damping effect is insufficient in overcoming the difficulty due to the “vortex stretching”, we seek unique global small solutions and the efforts have been mainly devoted to minimizing the smallness assumption. By positioning the solutions in a suitable functional setting (more precisely, the homogeneous Besov space B˚∞,11), we are able to obtain a unique global solution under a minimal smallness assumption.
EXACT SOLUTION FOR A TWO-DIMENSIONAL LAMB'S PROBLEM DUE TO A STRIP IMPULSE LOADING
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
By applying the integral transform method and the inverse transformation technique based upon the two types of integration, the present paper has successfully obtained an exact algebraic solution for a two-dimensional Lamb's problem due to a strip impulse loading for the first time. With the algebraic result, the excitation and propagation processes of stress waves,including the longitudinal wave, the transverse wave, and Rayleigh-wave, are discussed in detail.A few new conclusions have been drawn from currently available integral results or computational results.
Energy Technology Data Exchange (ETDEWEB)
Riley, M.E.
1998-03-01
This report describes the numerical procedure used to implement the Green`s function method for solving the Poisson equation in two-dimensional Cartesian coordinates. The procedure can determine the solution to a problem with any or all of applied voltage boundary conditions, dielectric media, floating (insulated) conducting media, dielectric surface charging, periodic (reflective) boundary conditions, and volumetric space charge. The numerical solution is reasonably fast, and the dimension of the linear problem to be solved is that of the number of elements needed to represent the surfaces, not the whole computational volume. The method of solution is useful in the simulation of plasma particle motion in the vicinity of complex surface structures as found in microelectronics plasma processing applications. A FORTRAN implementation of this procedure is available from the author.
Extrapolation of Nystrom solution for two dimensional nonlinear Fredholm integral equations
Guoqiang, Han; Jiong, Wang
2001-09-01
In this paper, we analyze the existence of asymptotic error expansion of the Nystrom solution for two-dimensional nonlinear Fredholm integral equations of the second kind. We show that the Nystrom solution admits an error expansion in powers of the step-size h and the step-size k. For a special choice of the numerical quadrature, the leading terms in the error expansion for the Nystrom solution contain only even powers of h and k, beginning with terms h2p and k2q. These expansions are useful for the application of Richardson extrapolation and for obtaining sharper error bounds. Numerical examples show that how Richardson extrapolation gives a remarkable increase of precision, in addition to faster convergence.
Cross Validation Through Two-dimensional Solution Surface for Cost-Sensitive SVM.
Gu, Bin; Sheng, Victor; Tay, Keng; Romano, Walter; Li, Shuo
2016-06-08
Model selection plays an important role in cost-sensitive SVM (CS-SVM). It has been proven that the global minimum cross validation (CV) error can be efficiently computed based on the solution path for one parameter learning problems. However, it is a challenge to obtain the global minimum CV error for CS-SVM based on one-dimensional solution path and traditional grid search, because CS-SVM is with two regularization parameters. In this paper, we propose a solution and error surfaces based CV approach (CV-SES). More specifically, we first compute a two-dimensional solution surface for CS-SVM based on a bi-parameter space partition algorithm, which can fit solutions of CS-SVM for all values of both regularization parameters. Then, we compute a two-dimensional validation error surface for each CV fold, which can fit validation errors of CS-SVM for all values of both regularization parameters. Finally, we obtain the CV error surface by superposing K validation error surfaces, which can find the global minimum CV error of CS-SVM. Experiments are conducted on seven datasets for cost sensitive learning and on four datasets for imbalanced learning. Experimental results not only show that our proposed CV-SES has a better generalization ability than CS-SVM with various hybrids between grid search and solution path methods, and than recent proposed cost-sensitive hinge loss SVM with three-dimensional grid search, but also show that CV-SES uses less running time.
Cao, Xiehong; Tan, Chaoliang; Zhang, Xiao; Zhao, Wei; Zhang, Hua
2016-08-01
The development of renewable energy storage and conversion devices is one of the most promising ways to address the current energy crisis, along with the global environmental concern. The exploration of suitable active materials is the key factor for the construction of highly efficient, highly stable, low-cost and environmentally friendly energy storage and conversion devices. The ability to prepare two-dimensional (2D) metal dichalcogenide (MDC) nanosheets and their functional composites in high yield and large scale via various solution-based methods in recent years has inspired great research interests in their utilization for renewable energy storage and conversion applications. Here, we will summarize the recent advances of solution-processed 2D MDCs and their hybrid nanomaterials for energy storage and conversion applications, including rechargeable batteries, supercapacitors, electrocatalytic hydrogen generation and solar cells. Moreover, based on the current progress, we will also give some personal insights on the existing challenges and future research directions in this promising field.
Solution of Two-Dimensional Viscous Flow Driven by Motion of Flexible Walls
Directory of Open Access Journals (Sweden)
Mohamed Gad-el-Hak
2010-03-01
Full Text Available An exact solution of the Navier–Stokes equations for a flow driven by motion of flexible wall is developed. A simple two-dimensional channel with deforming walls is considered as domain. The governing equations are linearized for low Reynolds number and large Womersley number Newtonian flows. Appropriate boundary conditions for general deformation are decomposed into harmonic excitations in space by Fourier series decomposition. A model of harmonic boundary deformation is considered and results are compared with computational fluid dynamics predictions. The results of velocity profiles across the channel and the centerline velocities of the channel are in good agreement with CFD solution. The analytical model developed provides quantitative descriptions of the flow field for a wide spectrum of actuating frequnecy and boundary conditions. The presented model can be used as an effective framework for preliminary design and optimization of displacement micropumps and other miniature applications.
Stochastic domain decomposition for the solution of the two-dimensional magnetotelluric problem
Bihlo, Alexander; Haynes, Ronald D; Loredo-Osti, J Concepcion
2016-01-01
Stochastic domain decomposition is proposed as a novel method for solving the two-dimensional Maxwell's equations as used in the magnetotelluric method. The stochastic form of the exact solution of Maxwell's equations is evaluated using Monte-Carlo methods taking into consideration that the domain may be divided into neighboring sub-domains. These sub-domains can be naturally chosen by splitting the sub-surface domain into regions of constant (or at least continuous) conductivity. The solution over each sub-domain is obtained by solving Maxwell's equations in the strong form. The sub-domain solver used for this purpose is a meshless method resting on radial basis function based finite differences. The method is demonstrated by solving a number of classical magnetotelluric problems, including the quarter-space problem, the block-in-half-space problem and the triangle-in-half-space problem.
General solution of the Dirac equation for quasi-two-dimensional electrons
Energy Technology Data Exchange (ETDEWEB)
Eremko, Alexander, E-mail: eremko@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Str., 14-b, Kyiv, 03680 (Ukraine); Brizhik, Larissa, E-mail: brizhik@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Str., 14-b, Kyiv, 03680 (Ukraine); Loktev, Vadim, E-mail: vloktev@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Str., 14-b, Kyiv, 03680 (Ukraine); National Technical University of Ukraine “KPI”, Peremohy av., 37, Kyiv, 03056 (Ukraine)
2016-06-15
The general solution of the Dirac equation for quasi-two-dimensional electrons confined in an asymmetric quantum well, is found. The energy spectrum of such a system is exactly calculated using special unitary operator and is shown to depend on the electron spin polarization. This solution contains free parameters, whose variation continuously transforms one known particular solution into another. As an example, two different cases are considered in detail: electron in a deep and in a strongly asymmetric shallow quantum well. The effective mass renormalized by relativistic corrections and Bychkov–Rashba coefficients are analytically obtained for both cases. It is demonstrated that the general solution transforms to the particular solutions, found previously (Eremko et al., 2015) with the use of spin invariants. The general solution allows to establish conditions at which a specific (accompanied or non-accompanied by Rashba splitting) spin state can be realized. These results can prompt the ways to control the spin degree of freedom via the synthesis of spintronic heterostructures with the required properties.
Du, Yijun; Segall, Paul; Gao, Huajian
1994-07-01
Quasi-static elastic dislocations in a homogeneous elastic half-space are commonly used to model earthquake faulting processes. Recent studies of the 1989 Kalapana, Hawaii, and Loma Prieta, California, earthquakes suggest that spatial variations in elastic properties are necessary to reconcile geodetic and seismic results. In this paper, we use a moduli perturbation approach to investigate the effect of lateral and vertical variations in elastic properties on the elastic fields produced by dislocations. The method is simple, efficient, and in some cases leads to closed form solutions. The zero-order solution is simply the solution for a homogeneous body. The first-order correction for elastic heterogeneity is given by a volume integral involving the spatial variations in moduli, the displacements due to a dislocation in a homogeneous half-space, and the half-space Green's function. The same representation can be also used to obtain higher-order solutions. If there are only piecewise constant variations in shear modulus, the volume integral can be reduced to a surface integral (or line integral in two-dimensions). Comparisons with the analytical solutions for a screw dislocation in a layered medium suggest that the perturbation solutions are valid for nearly an order of magnitude variation in modulus. It is shown that a simple two-dimensional model with both vertical and lateral variations in the elastic properties may explain a large part of the discrepancy between seismic and geodetically inferred fault depths for the 1989 Kalapana, Hawaii, earthquake.
National Research Council Canada - National Science Library
S Pamuk; N Pamuk
2014-01-01
In this paper, we obtain the particular exact solutions of the two-dimensional heat and mass transfer equation with power-law temperature-dependent thermal con- ductivity using the Adomian's decomposition method...
Numerical analysis of singular solutions of two-dimensional problems of asymmetric elasticity
Korepanov, V. V.; Matveenko, V. P.; Fedorov, A. Yu.; Shardakov, I. N.
2013-07-01
An algorithm for the numerical analysis of singular solutions of two-dimensional problems of asymmetric elasticity is considered. The algorithm is based on separation of a power-law dependence from the finite-element solution in a neighborhood of singular points in the domain under study, where singular solutions are possible. The obtained power-law dependencies allow one to conclude whether the stresses have singularities and what the character of these singularities is. The algorithm was tested for problems of classical elasticity by comparing the stress singularity exponents obtained by the proposed method and from known analytic solutions. Problems with various cases of singular points, namely, body surface points at which either the smoothness of the surface is violated, or the type of boundary conditions is changed, or distinct materials are in contact, are considered as applications. The stress singularity exponents obtained by using the models of classical and asymmetric elasticity are compared. It is shown that, in the case of cracks, the stress singularity exponents are the same for the elasticity models under study, but for other cases of singular points, the stress singularity exponents obtained on the basis of asymmetric elasticity have insignificant quantitative distinctions from the solutions of the classical elasticity.
Hydration of an apolar solute in a two-dimensional waterlike lattice fluid.
Buzano, C; De Stefanis, E; Pretti, M
2005-05-01
In a previous work, we investigated a two-dimensional lattice-fluid model, displaying some waterlike thermodynamic anomalies. The model, defined on a triangular lattice, is now extended to aqueous solutions with apolar species. Water molecules are of the "Mercedes Benz" type, i.e., they possess a D3 (equilateral triangle) symmetry, with three equivalent bonding arms. Bond formation depends both on orientation and local density. The insertion of inert molecules displays typical signatures of hydrophobic hydration: large positive transfer free energy, large negative transfer entropy (at low temperature), strong temperature dependence of the transfer enthalpy and entropy, i.e., large (positive) transfer heat capacity. Model properties are derived by a generalized first order approximation on a triangle cluster.
The solution of the two-dimensional sine-Gordon equation using the method of lines
Bratsos, A. G.
2007-09-01
The method of lines is used to transform the initial/boundary-value problem associated with the two-dimensional sine-Gordon equation in two space variables into a second-order initial-value problem. The finite-difference methods are developed by replacing the matrix-exponential term in a recurrence relation with rational approximants. The resulting finite-difference methods are analyzed for local truncation error, stability and convergence. To avoid solving the nonlinear system a predictor-corrector scheme using the explicit method as predictor and the implicit as corrector is applied. Numerical solutions for cases involving the most known from the bibliography line and ring solitons are given.
Xu, Chunhui; He, Ping; Liu, Jie; Cui, Ajuan; Dong, Huanli; Zhen, Yonggang; Chen, Wei; Hu, Wenping
2016-08-08
Two-dimensional (2D) crystals of organic semiconductors (2DCOS) have attracted attention for large-area and low-cost flexible optoelectronics. However, growing large 2DCOS in controllable ways and transferring them onto technologically important substrates, remain key challenges. Herein we report a facile, general, and effective method to grow 2DCOS up to centimeter size which can be transferred to any substrate efficiently. The method named "solution epitaxy" involves two steps. The first is to self-assemble micrometer-sized 2DCOS on water surface. The second is epitaxial growth of them into millimeter or centimeter sized 2DCOS with thickness of several molecular layers. The general applicability of this method for the growth of 2DCOS is demonstrated by nine organic semiconductors with different molecular structures. Organic field-effect transistors (OFETs) based on the 2DCOS demonstrated high performance, confirming the high quality of the 2DCOS.
Full two-dimensional transient solutions of electrothermal aircraft blade deicing
Masiulaniec, K. C.; Keith, T. G., Jr.; Dewitt, K. J.; Leffel, K. L.
1985-01-01
Two finite difference methods are presented for the analysis of transient, two-dimensional responses of an electrothermal de-icer pad of an aircraft wing or blade with attached variable ice layer thickness. Both models employ a Crank-Nicholson iterative scheme, and use an enthalpy formulation to handle the phase change in the ice layer. The first technique makes use of a 'staircase' approach, fitting the irregular ice boundary with square computational cells. The second technique uses a body fitted coordinate transform, and maps the exact shape of the irregular boundary into a rectangular body, with uniformally square computational cells. The numerical solution takes place in the transformed plane. Initial results accounting for variable ice layer thickness are presented. Details of planned de-icing tests at NASA-Lewis, which will provide empirical verification for the above two methods, are also presented.
Nanoclays: Two-dimensional shuttles for rare earth complexes in aqueous solution
Lezhnina, M. M.; Bentlage, M.; Kynast, U. H.
2011-08-01
Nanoclays are shown to be attractive substrates in at least two major respects. Firstly, Hectorite analogous commercial clays ("Laponite") can facilitate the usage of luminescent rare earth ions in aqueous solution, as their adherence to the clay surface strongly reduces water coordination and thus enables dramatically improved emission intensities. This also holds true for complexes of Tb 3+, which coordinate water in their native crystalline state, as demonstrated for tris(bipyiridine) complexes. For these, the laponite interaction affords a 16-fold gain in emission intensity in aqueous solution over the dissolved complex. Secondly, the two-dimensional, disk-like morphology of the clays enables a sufficient proximity of Ce 3+ and Tb 3+ to allow an energy transfer even at comparably low solution concentrations. In partially laminated, solid powders the efficiencies of the corresponding interlayer species decrease due to intimate interactions with the surrounding silicate and interlayer water, which can, however be counteracted by keeping the disks apart with long-chain, alkylammonium cations as spacers between the disks.
Non-Lie Symmetry Group and New Exact Solutions for the Two-Dimensional KdV-Burgers Equation
Institute of Scientific and Technical Information of China (English)
WANG Hong; TIAN Ying-Hui; CHEN Han-Lin
2011-01-01
@@ By using the modified Clarkson-Kruskal (CK) direct method, we obtain the non-Lie symmetry group of the two-dimensional KdV-Burgers equation.Under some constraint conditions, Lie point symmetry is also obtained.Through the symmetry group, some new exact solutions of the two-dimensional KdV-Burgers equation are found.%By using the modified Clarkson-Kruskal (CK) direct method, we obtain the non-Lie symmetry group of the two-dimensional KdV-Burgers equation. Under some constraint conditions, Lie point symmetry is also obtained.Through the symmetry group, some new exact solutions of the two-dimensional KdV-Burgers equation are found.
How the World Changes By Going from One- to Two-Dimensional Polymers in Solution.
Schlüter, A Dieter; Payamyar, Payam; Öttinger, Hans Christian
2016-10-01
Scaling behavior of one-dimensional (1D) and two-dimensional (2D) polymers in dilute solution is discussed with the goal of stimulating experimental work by chemists, physicists, and material scientists in the emerging field of 2D polymers. The arguments are based on renormalization-group theory, which is explained for a general audience. Many ideas and methods successfully applied to 1D polymers are found not to work if one goes to 2D polymers. The role of the various states exhibiting universal behavior is turned upside down. It is expected that solubility will be a serious challenge for 2D polymers. Therefore, given the crucial importance of solutions in characterization and processing, synthetic concepts are proposed that allow the local bending rigidity and the molar mass to be tuned and the long-range interactions to be engineered, all with the goal of preventing the polymer from falling into flat or compact states. © 2016 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Indian Academy of Sciences (India)
ALY R SEADAWY
2017-09-01
Nonlinear two-dimensional Kadomtsev–Petviashvili (KP) equation governs the behaviour of nonlinear waves in dusty plasmas with variable dust charge and two temperature ions. By using the reductive perturbation method, the two-dimensional dust-acoustic solitary waves (DASWs) in unmagnetized cold plasma consisting of dust fluid, ions and electrons lead to a KP equation. We derived the solitary travelling wave solutions of the twodimensional nonlinear KP equation by implementing sech–tanh, sinh–cosh, extended direct algebraic and fraction direct algebraicmethods. We found the electrostatic field potential and electric field in the form travellingwave solutions for two-dimensional nonlinear KP equation. The solutions for the KP equation obtained by using these methods can be demonstrated precisely and efficiency. As an illustration, we used the readymade package of $\\it{Mathematica}$ program 10.1 to solve the original problem. These solutions are in good agreement with the analytical one.
Exact solutions of a two-dimensional cubic–quintic discrete nonlinear Schrödinger equation
DEFF Research Database (Denmark)
Khare, Avinash; Rasmussen, Kim Ø; Samuelsen, Mogens Rugholm
2011-01-01
We show that a two-dimensional generalized cubic–quintic Ablowitz–Ladik lattice admits periodic solutions that can be expressed in analytical form. The framework for the stability analysis of these solutions is developed and applied to reveal the intricate stability behavior of this nonlinear sys...
Directory of Open Access Journals (Sweden)
Neng Wan
2014-01-01
Full Text Available In terms of the poor geometric adaptability of spline element method, a geometric precision spline method, which uses the rational Bezier patches to indicate the solution domain, is proposed for two-dimensional viscous uncompressed Navier-Stokes equation. Besides fewer pending unknowns, higher accuracy, and computation efficiency, it possesses such advantages as accurate representation of isogeometric analysis for object boundary and the unity of geometry and analysis modeling. Meanwhile, the selection of B-spline basis functions and the grid definition is studied and a stable discretization format satisfying inf-sup conditions is proposed. The degree of spline functions approaching the velocity field is one order higher than that approaching pressure field, and these functions are defined on one-time refined grid. The Dirichlet boundary conditions are imposed through the Nitsche variational principle in weak form due to the lack of interpolation properties of the B-splines functions. Finally, the validity of the proposed method is verified with some examples.
Solution of two-dimensional Fredholm integral equation via RBF-triangular method
Directory of Open Access Journals (Sweden)
Amir Fallahzadeh
2012-04-01
Full Text Available In this paper, a new method is introduced to solve a two-dimensional Fredholm integral equation. The method is based on the approximation by Gaussian radial basis functions and triangular nodes and weights. Also, a new quadrature is introduced to approximate the two dimensional integrals which is called the triangular method. The results of the example illustrate the accuracy of the proposed method increases.
Institute of Scientific and Technical Information of China (English)
GONG Lun-Xun; CAO Jian-Li; PAN Jun-Ting; ZHANG Hua; JIAO Wan-Tang
2008-01-01
Based on the second integrable case of known two-dimensional Hamiltonian system with a quartic potential, we propose a 4×4 matrix spectral problem and derive a hierarchy of coupled KdV equations and their Hamiltonian structures. It is shown that solutions of the coupled KdV equations in the hierarchy are reduced to solving two compatible systems of ordinary differential equations. As an application, quite a few explicit solutions of the coupled KdV equations are obtained via using separability for the second integrable case of the two-dimensional Hamiltonian system.
Directory of Open Access Journals (Sweden)
S. M. Sadatrasoul
2014-01-01
Full Text Available We introduce some generalized quadrature rules to approximate two-dimensional, Henstock integral of fuzzy-number-valued functions. We also give error bounds for mappings of bounded variation in terms of uniform modulus of continuity. Moreover, we propose an iterative procedure based on quadrature formula to solve two-dimensional linear fuzzy Fredholm integral equations of the second kind (2DFFLIE2, and we present the error estimation of the proposed method. Finally, some numerical experiments confirm the theoretical results and illustrate the accuracy of the method.
Institute of Scientific and Technical Information of China (English)
XING Yong-Zhong
2009-01-01
The analytical solution of a multidimensional Langevin equation at the overdamping limit is obtained and the probability of particles passing over a two-dimensional saddle point is discussed. These results may break a path for studying further the fusion in superheavy elements synthesis.
Zabihi, F.; Saffarian, M.
2016-07-01
The aim of this article is to obtain the numerical solution of the two-dimensional KdV-Burgers equation. We construct the solution by using a different approach, that is based on using collocation points. The solution is based on using the thin plate splines radial basis function, which builds an approximated solution with discretizing the time and the space to small steps. We use a predictor-corrector scheme to avoid solving the nonlinear system. The results of numerical experiments are compared with analytical solutions to confirm the accuracy and efficiency of the presented scheme.
Energy Technology Data Exchange (ETDEWEB)
Chen, Yong [Ningbo Univ., Ningbo (China). Department of Mathematics; Shanghai Jiao-Tong Univ., Shangai (China). Department of Physics; Chinese Academy of sciences, Beijing (China). Key Laboratory of Mathematics Mechanization
2005-03-01
A general method to uniformly construct exact solutions in terms of special function of nonlinear partial differential equations is presented by means of a more general ansatz and symbolic computation. Making use of the general method, we can successfully obtain the solutions found by the method proposed by Fan (J. Phys. A., 36 (2003) 7009) and find other new and more general solutions, which include polynomial solutions, exponential solutions, rational solutions, triangular periodic wave solution, soliton solutions, soliton-like solutions and Jacobi, Weierstrass doubly periodic wave solutions. A general variable-coefficient two-dimensional KdV equation is chosen to illustrate the method. As a result, some new exact soliton-like solutions are obtained. planets. The numerical results are given in tables. The results are discussed in the conclusion.
Analytic solution of a relativistic two-dimensional hydrogen-like atom in a constant magnetic field
Energy Technology Data Exchange (ETDEWEB)
Villalba, V.M. [Instituto Venezolano de Investigaciones Cientificas, Caracas (Venezuela). Centro de Fisica; Pino, R. [Instituto Venezolano de Investigaciones Cientificas, Caracas (Venezuela). Centro de Fisica]|[Centro de Quimica, Instituto Venezolano de Investigaciones Cientificas, IVIC, Apdo 21827, Caracas 1020-A (Venezuela)
1998-01-26
We obtain exact solutions of the Klein-Gordon and Pauli-Schroedinger equations for a two-dimensional hydrogen-like atom in the presence of a constant magnetic field. Analytic solutions for the energy spectrum are obtained for particular values of the magnetic field strength. The results are compared to those obtained in the non-relativistic and spinless case. We obtain that the relativistic spectrum does not present s states. (orig.). 7 refs.
Baiz, Carlos R; Peng, Chunte Sam; Reppert, Mike E; Jones, Kevin C; Tokmakoff, Andrei
2012-04-21
We present a method to quantitatively determine the secondary structure composition of globular proteins using coherent two-dimensional infrared (2DIR) spectroscopy of backbone amide I vibrations (1550-1720 cm(-1)). Sixteen proteins with known crystal structures were used to construct a library of 2DIR spectra, and the fraction of residues in α-helix, β-sheet, and unassigned conformations was determined by singular value decomposition (SVD) of the measured two-dimensional spectra. The method was benchmarked by removing each individual protein from the set and comparing the composition extracted from 2DIR against the composition determined from the crystal structures. To highlight the increased structural content extracted from 2DIR spectra a similar analysis was also carried out using conventional infrared absorption of the proteins in the library.
Directory of Open Access Journals (Sweden)
H. S. Shukla
2014-11-01
Full Text Available In this paper, a numerical solution of two dimensional nonlinear coupled viscous Burger equation is discussed with appropriate initial and boundary conditions using the modified cubic B-spline differential quadrature method. In this method, the weighting coefficients are computed using the modified cubic B-spline as a basis function in the differential quadrature method. Thus, the coupled Burger equation is reduced into a system of ordinary differential equations. An optimal five stage and fourth-order strong stability preserving Runge–Kutta scheme is applied for solving the resulting system of ordinary differential equations. The accuracy of the scheme is illustrated by taking two numerical examples. Computed results are compared with the exact solutions and other results available in literature. Obtained numerical result shows that the described method is efficient and reliable scheme for solving two dimensional coupled viscous Burger equation.
Finite Differences and Collocation Methods for the Solution of the Two Dimensional Heat Equation
Kouatchou, Jules
1999-01-01
In this paper we combine finite difference approximations (for spatial derivatives) and collocation techniques (for the time component) to numerically solve the two dimensional heat equation. We employ respectively a second-order and a fourth-order schemes for the spatial derivatives and the discretization method gives rise to a linear system of equations. We show that the matrix of the system is non-singular. Numerical experiments carried out on serial computers, show the unconditional stability of the proposed method and the high accuracy achieved by the fourth-order scheme.
Fang, Li; Guo, Zhenhua
2016-04-01
The aim of this paper is to establish the global well-posedness and large-time asymptotic behavior of the strong solution to the Cauchy problem of the two-dimensional compressible Navier-Stokes equations with vacuum. It is proved that if the shear viscosity {μ} is a positive constant and the bulk viscosity {λ} is the power function of the density, that is, {λ=ρ^{β}} with {β in [0,1],} then the Cauchy problem of the two-dimensional compressible Navier-Stokes equations admits a unique global strong solution provided that the initial data are of small total energy. This result can be regarded as the extension of the well-posedness theory of classical compressible Navier-Stokes equations [such as Huang et al. (Commun Pure Appl Math 65:549-585, 2012) and Li and Xin (http://arxiv.org/abs/1310.1673) respectively]. Furthermore, the large-time behavior of the strong solution to the Cauchy problem of the two-dimensional barotropic compressible Navier-Stokes equations had been also obtained.
Ahmad, Shahab; Kanaujia, Pawan K; Beeson, Harry J; Abate, Antonio; Deschler, Felix; Credgington, Dan; Steiner, Ullrich; Prakash, G Vijaya; Baumberg, Jeremy J
2015-11-18
Room-temperature photocurrent measurements in two-dimensional (2D) inorganic-organic perovskite devices reveal that excitons strongly contribute to the photocurrents despite possessing binding energies over 10 times larger than the thermal energies. The p-type (C6H9C2H4NH3)2PbI4 liberates photocarriers at metallic Schottky aluminum contacts, but incorporating electron- and hole-transport layers enhances the extracted photocurrents by 100-fold. A further 10-fold gain is found when TiO2 nanoparticles are directly integrated into the perovskite layers, although the 2D exciton semiconducting layers are not significantly disrupted. These results show that strong excitonic materials may be useful as photovoltaic materials despite high exciton binding energies and suggest mechanisms to better understand the photovoltaic properties of the related three-dimensional perovskites.
A solution of two-dimensional magnetohydrodynamic flow using the finite volume method
Directory of Open Access Journals (Sweden)
Naceur Sonia
2014-01-01
Full Text Available This paper presents the two dimensional numerical modeling of the coupling electromagnetic-hydrodynamic phenomena in a conduction MHD pump using the Finite volume Method. Magnetohydrodynamic problems are, thus, interdisciplinary and coupled, since the effect of the velocity field appears in the magnetic transport equations, and the interaction between the electric current and the magnetic field appears in the momentum transport equations. The resolution of the Maxwell's and Navier Stokes equations is obtained by introducing the magnetic vector potential A, the vorticity z and the stream function y. The flux density, the electromagnetic force, and the velocity are graphically presented. Also, the simulation results agree with those obtained by Ansys Workbench Fluent software.
A meron cluster solution for the sign problem of the two-dimensional O(3) model
Brechtefeld, F
2002-01-01
The two-dimensional O(3) model at a vacuum angle theta=pi is investigated. This model has a severe sign problem. By a Wolff cluster algorithm an integer or half-integer topological charge is assigned to each cluster. The meron clusters (clusters with half-integer topological charge) are used to construct an improved estimator for the correlation function of two spins at theta=pi. Only configurations with 0 and 2 merons contribute to this correlation function. An algorithm, that generates configurations with only 0 and 2 merons, is constructed and numerical simulations at theta=pi are performed. The numerical results indicate the presence of long range correlations at theta=pi.
Directory of Open Access Journals (Sweden)
Fukang Yin
2013-01-01
Full Text Available A numerical method is presented to obtain the approximate solutions of the fractional partial differential equations (FPDEs. The basic idea of this method is to achieve the approximate solutions in a generalized expansion form of two-dimensional fractional-order Legendre functions (2D-FLFs. The operational matrices of integration and derivative for 2D-FLFs are first derived. Then, by these matrices, a system of algebraic equations is obtained from FPDEs. Hence, by solving this system, the unknown 2D-FLFs coefficients can be computed. Three examples are discussed to demonstrate the validity and applicability of the proposed method.
Directory of Open Access Journals (Sweden)
M. P. Markakis
2010-01-01
Full Text Available Through a suitable ad hoc assumption, a nonlinear PDE governing a three-dimensional weak, irrotational, steady vector field is reduced to a system of two nonlinear ODEs: the first of which corresponds to the two-dimensional case, while the second involves also the third field component. By using several analytical tools as well as linear approximations based on the weakness of the field, the first equation is transformed to an Abel differential equation which is solved parametrically. Thus, we obtain the two components of the field as explicit functions of a parameter. The derived solution is applied to the two-dimensional small perturbation frictionless flow past solid surfaces with either sinusoidal or parabolic geometry, where the plane velocities are evaluated over the body's surface in the case of a subsonic flow.
Wu, Wan-ye; Wu, Kun; Li, Guo-ying
2015-02-01
The synchronous fluorescence spectroscopy and two dimensional correlation analysis method were applied to study the aggregation behavior of acid-soluble collagen solutions (0.2, 0.4 and 1.6 mg x mL(-1)) during the heating process of 10-70 degrees C. It was found that the fluorescence excited at 292 and 282 nm (delta lamda=9 nm) belongs to the tyrosine (Tyr) residues which participate in forming hydrogen bonds or not, respectively. The two dimensional correlation analysis with the temperature varying showed that with the temperature increased (10-30 degrees C) hydrogen bonds among collagen molecular with Tyr residues formed in the 0.2 mg x mL(-1) collagen solution, while the higher aggregations of collagen molecular and hydrophobic micro-domains appeared in the 0.4 and 1.6 mg x mL(-1) collagen solutions. With approaching the denatured temperature of collagen (36-38 degrees C), the hydrophobic micro-domain and aggregates seemed to be broken in the 0.4 and 1.6 mg x mL(-1) collagen solutions, however the hydrogen bonds in the 0.2 mg x mL(-1) were stable. Above the denaturation temperature of collagen, the triple-helix structure of collagen molecular in solution of each concentration tended to be loose. In the heating process of 45-70 degrees C, this trend was more obvious.
Numerical solutions for a two-dimensional airfoil undergoing unsteady motion
Institute of Scientific and Technical Information of China (English)
WU Fu-bing; ZENG Nian-dong; ZHANG Liang; WU De-ming
2004-01-01
Continuous vorticity panels are used to model general unsteady inviscid, incompressible, and two-dimensional flows. The geometry of the airfoil is approximated by series of short straight segments having endpoints that lie on the actual surface. A piecewise linear, continuous distribution of vorticity over the airfoil surface is used to generate disturbance flow. The no-penetration condition is imposed at the midpoint of each segment and at discrete times. The wake is simulated by a system of point vortices, which move at local fluid velocity. At each time step, a new wake panel with uniform vorticity distribution is attached to the trailing edge, and the condition of eonstant circulation around the airfoil and wake is imposed. A new expression for Kutta condition is developed to study (i) the effect of thickness on the lift build-up of an impulsively started airfoil, (ii) the effects of reduced frequency and heave amplitude on the thrust production of flapping airfoils, and (iii) the vortex-airfoil interaction. This work presents some hydrodynamic results for tidalstreaim turbine.
Shen, Yang; Qiu, Chenchen; Li, Yande; Shi, Wen; Rui, Xiaoxi
2017-01-01
China is a country with vast territory, but economic development and population growth have reduced the usable land resources in recent years. Therefore, reclamation by pumping and filling is carried out in eastern coastal regions of China in order to meet the needs of urbanization. However, large areas of reclaimed land need rapid drainage consolidation treatment. Based on past researches on how to improve the treatment efficiency of soft clay using vacuum preloading combined with electro-osmosis, a two-dimensional drainage plane model was proposed according to the Terzaghi and Esrig consolidation theory. However, the analytical solution using two-dimensional plane model was never involved. Current analytical solutions can't have a thorough theoretical analysis of practical engineering and give relevant guidance. Considering the smearing effect and the rectangle arrangement pattern, an analytical solution is derived to describe the behavior of pore-water and the consolidation process by using EKG (electro-kinetic geo synthetics) materials. The functions of EKG materials include drainage, electric conduction and corrosion resistance. Comparison with test results is carried out to verify the analytical solution. It is found that the measured value is larger than the applied vacuum degree because of the stacking effect of the vacuum preloading and electro-osmosis. The trends of the mean measured value and the mean analytical value processes are comparable. Therefore, the consolidation model can accurately assess the change in pore-water pressure and the consolidation process during vacuum preloading combined with electro-osmosis.
Directory of Open Access Journals (Sweden)
Mohammad Mehdi Rashidi
2008-01-01
Full Text Available The flow of a viscous incompressible fluid between two parallel plates due to the normal motion of the plates is investigated. The unsteady Navier-Stokes equations are reduced to a nonlinear fourth-order differential equation by using similarity solutions. Homotopy analysis method (HAM is used to solve this nonlinear equation analytically. The convergence of the obtained series solution is carefully analyzed. The validity of our solutions is verified by the numerical results obtained by fourth-order Runge-Kutta.
Directory of Open Access Journals (Sweden)
M. R. Astaraki
2012-01-01
Full Text Available In the present study analytical solution for forced convection heat transfer in a circular duct with a special boundary condition has been presented, because the external wall temperature is a periodic function of axial direction. Local energy balance equation is written with reference to the fully developed regime. Also governing equations are two-dimensionally solved, and the effect of duct wall thickness has been considered. The temperature distribution of fluid and solid phases is assumed as a periodic function of axial direction and finally temperature distribution in the flow field, solid wall, and local Nusselt number, is obtained analytically.
Energy Technology Data Exchange (ETDEWEB)
Kohlberg, I.
1989-03-01
A solution for the two-dimensional, two-region electromagnetic ground response was developed that relates the surface components of the electric field to the surface components of the magnetic field. This has been accomplished by deriving a universal functional form for a dimensionless Green's function. The Green's function provides increasingly more accurate approximations to the response for each successive reflection from the second layer. This result would appear to provide simplification and reduced computer running time in the numerical modelling of the HABEMP when the ground response is coupled to finite-difference methods for solving the atmospheric part of the problem.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The authors consider the existence of singular limit solutions for a family of nonlinear elliptic problems with exponentially dominated nonlinearity and Dirichlet boundary condition and generalize the results of [3].
A Global Solution to a Two-dimensional Riemann Problem Involving Shocks as Free Boundaries
Institute of Scientific and Technical Information of China (English)
Yuxi Zheng
2003-01-01
We present a global solution to a Riemann problem for the pressure gradient system of equations.The Riemann problem has initially two shock waves and two contact discontinuities. The angle between the two shock waves is set initially to be close to 180 degrees. The solution has a shock wave that is usually regarded as a free boundary in the self-similar variable plane. Our main contribution in methodology is handling the tangential oblique derivative boundary values.
Institute of Scientific and Technical Information of China (English)
ZHANG XingHua; HOU XiMiao; JI Chao; LI Ming; DOU ShuoXing; WANG PengYe
2009-01-01
With atomic force microscopy (AFM) we systematically studied the DNA condensations on mica surfaces induced by multivalent cation spermidine. The pattern of the DNA condensates is a flat single layer, with a core in the centre and DNA wrapping around it at high density. We assume this to be a two-dimensional condensation of free coiled DNA onto negatively charged mica surfaces by the multivalent cation. The DNA molecules condense on mica surfaces via a pathway different from the formation of toroids, rods or globules in bulk solutions. We give an explanation to why toroid structures are difficult to be observed by AFM, and further discuss the relationship between DNA condensations in solutions and on mica surfaces. The present work will be helpful for understanding the behaviors of DNA on charged surfaces, which might be significantly different from that in solutions.
Numerical Solutions for Supersonic Flow of an Ideal Gas Around Blunt Two-Dimensional Bodies
Fuller, Franklyn B.
1961-01-01
The method described is an inverse one; the shock shape is chosen and the solution proceeds downstream to a body. Bodies blunter than circular cylinders are readily accessible, and any adiabatic index can be chosen. The lower limit to the free-stream Mach number available in any case is determined by the extent of the subsonic field, which in turn depends upon the body shape. Some discussion of the stability of the numerical processes is given. A set of solutions for flows about circular cylinders at several Mach numbers and several values of the adiabatic index is included.
Szmelter, J.; Marchant, M. J.; Evans, A.; Weatherill, N. P.
A cell vertex finite volume Jameson scheme is used to solve the 2D compressible, laminar, viscous fluid flow equations on locally embedded multiblock meshes. The proposed algorithm is applicable to both the Euler and Navier-Stokes equations. It is concluded that the adaptivity method is very successful in efficiently improving the accuracy of the solution. Both the mesh generator and the flow equation solver which are based on a quadtree data structure offer good flexibility in the treatment of interfaces. It is concluded that methods under consideration lead to accurate flow solutions.
Soliton solutions in two-dimensional Lorentz-violating higher derivative scalar theory
Passos, E; Brito, F A; Menezes, R; Mota-Silva, J C; Santos, J R L
2016-01-01
This paper shows a new approach to obtain analytical topological defects for a 2D Myers-Pospelov Lagrangian for two scalar fields. Such a Lagrangian presents higher-order kinetic terms, which lead us to equations of motion which are non-trivial to be integrated. Here we describe three possible scenarios for the equations of motion, named by time-like, space-like and light-like respectively. We started our investigation with a kink-like travelling wave Ansatz for the free theory, which led us to constraints for the dispersion relations of each scenario. We also introduced a method to obtain analytical solution for the general theory in the three mentioned scenarios. We exemplified the method and discussed the behavior of the defects solutions.
Two dimensional analytical solution for a partially vegetated compound channel flow
Institute of Scientific and Technical Information of China (English)
HUAI Wen-xin; XU Zhi-gang; YANG Zhong-hua; ZENG Yu-hong
2008-01-01
The theory of an eddy viscosity model is applied to the study of the flow in a compound channel which is partially vegetated. The governing equation is constituted by analyzing the longitudinal forces acting on the unit volume where the effect of the vegetation on the flow is considered as a drag force item. The compound channel is di- vided into 3 sub-regions in the transverse direction, and the coefficients in every region's differential equations were solved simultaneously. Thus, the analytical solution of the transverse distribution of the depth-averaged velocity for uniform flow in a partially vege- tated compound channel was obtained. The results can be used to predict the transverse distribution of bed shear stress, which has an important effect on the transportation of sediment. By comparing the analytical results with the measured data, the analytical so- lution in this paper is shown to be sufficiently accurate to predict most hydraulic features for engineering design purposes.
Directory of Open Access Journals (Sweden)
Kalyani Kathirgamanathan
2015-01-01
Full Text Available In this study two-dimensional FTIR analysis was applied to understand the temperature effects on processing cellulose solutions in imidazolium-based ionic liquids. Analysis of the imidazolium ion νC2–H peak revealed hydrogen bonding within cellulose solutions to be dynamic on heating and cooling. The extent of hydrogen bonding was stronger on heating, consistent with greater ion mobility at higher temperature when the ionic liquid network structure is broken. At ambient temperatures a blue shifted νC2–H peak was indicative of greater cation-anion interactions, consistent with the ionic liquid network structure. Both cellulose and water further impact the extent of hydrogen bonding in these solutions. The FTIR spectral changes appeared gradual with temperature and contrast shear induced rheology changes which were observed on heating above 70°C and cooling below 40°C. The influence of cellulose on solution viscosity was not distinguished on initial heating as the ionic liquid network structure dominates rheology behaviour. On cooling, the quantity of cellulose has a greater influence on solution rheology. Outcomes suggest processing cellulose in ionic liquids above 40°C and to reduce the impacts of cation-anion effects and enhance solubilisation, processing should be done at 70°C.
Energy Technology Data Exchange (ETDEWEB)
Hoang-Do, Ngoc-Tram; Hoang, Van-Hung; Le, Van-Hoang [Department of Physics, Ho Chi Minh City University of Pedagogy, 280 An Duong Vuong Street, District 5, Ho Chi Minh City (Viet Nam)
2013-05-15
The Feranchuk-Komarov operator method is developed by combining with the Levi-Civita transformation in order to construct analytical solutions of the Schroedinger equation for a two-dimensional exciton in a uniform magnetic field of arbitrary strength. As a result, analytical expressions for the energy of the ground and excited states are obtained with a very high precision of up to four decimal places. Especially, the precision is uniformly stable for the whole range of the magnetic field. This advantage appears due to the consideration of the asymptotic behaviour of the wave-functions in strong magnetic field. The results could be used for various physical analyses and the method used here could also be applied to other atomic systems.
Directory of Open Access Journals (Sweden)
N. N. Nefedov
2016-01-01
Full Text Available Parabolic singularly perturbed problems have been actively studied in recent years in connection with a large number of practical applications: chemical kinetics, synergetics, astrophysics, biology, and so on. In this work a singularly perturbed periodic problem for a parabolic reaction-diﬀusion equation is studied in the two-dimensional case. The case when there is an internal transition layer under unbalanced nonlinearity is considered. The internal layer is localised near the so called transitional curve. An asymptotic expansion of the solution is constructed and an asymptotics for the transitional curve is determined. The asymptotical expansion consists of a regular part, an interior layer part and a boundary part. In this work we focus on the interior layer part. In order to describe it in the neighborhood of the transition curve the local coordinate system is introduced and the stretched variables are used. To substantiate the asymptotics thus constructed, the asymptotic method of diﬀerential inequalities is used. The upper and lower solutions are constructed by suﬃciently complicated modiﬁcation of the asymptotic expansion of the solution. The Lyapunov asymptotical stability of the solution was proved by using the method of contracting barriers. This method is based on the asymptotic comparison principle and uses the upper and lower solutions which are exponentially tending to the solution to the problem. As a result, the solution is locally unique.The article is published in the authors’ wording.
Zech, Alraune; Attinger, Sabine
2016-05-01
A new method is presented which allows interpreting steady-state pumping tests in heterogeneous isotropic transmissivity fields. In contrast to mean uniform flow, pumping test drawdowns in heterogeneous media cannot be described by a single effective or equivalent value of hydraulic transmissivity. An effective description of transmissivity is required, being a function of the radial distance to the well and including the parameters of log-transmissivity: mean, variance, and correlation length. Such a model is provided by the upscaling procedure radial coarse graining, which describes the transition of near-well to far-field transmissivity effectively. Based on this approach, an analytical solution for a steady-state pumping test drawdown is deduced. The so-called effective well flow solution is derived for two cases: the ensemble mean of pumping tests and the drawdown within an individual heterogeneous transmissivity field. The analytical form of the solution allows inversely estimating the parameters of aquifer heterogeneity. For comparison with the effective well flow solution, virtual pumping tests are performed and analysed for both cases, the ensemble mean drawdown and pumping tests at individual transmissivity fields. Interpretation of ensemble mean drawdowns showed proof of the upscaling method. The effective well flow solution reproduces the drawdown for two-dimensional pumping tests in heterogeneous media in contrast to Thiem's solution for homogeneous media. Multiple pumping tests conducted at different locations within an individual transmissivity field are analysed, making use of the effective well flow solution to show that all statistical parameters of aquifer heterogeneity can be inferred under field conditions. Thus, the presented method is a promising tool with which to estimate parameters of aquifer heterogeneity, in particular variance and horizontal correlation length of log-transmissivity fields from steady-state pumping test measurements.
Robert, Thomas; Martel, Richard; Conrad, Stephen H; Lefebvre, René; Gabriel, Uta
2006-06-30
This research focused on the optimization of TCE dissolution in a physical two-dimensional model providing a realistic representation of a heterogeneous granular aquifer. TCE was infiltrated in the sand pack where it resided both in pools and in zones of residual saturation. Surfactant was initially injected at low concentration to minimize TCE remobilization at first contact but was incrementally increased later during the experiment. Xanthan gum was added to the injected surfactant solution to optimize the sweep efficiency through the heterogeneous medium. Photographs and digital image analysis illustrated the interactions between TCE and the injected fluids. During the polymer flood, the effects of heterogeneities inside the sand pack were greatly reduced by the increased fluid viscosity and the shear-thinning effects of the polymer. The polymer also improved the contact between the TCE ganglia and the surfactant-polymer solution, thereby promoting dissolution. Surfactants interacted with the polymer reducing the overall viscosity of the solution. At first contact with a 0.5%(mass) surfactant solution, the TCE pools drained and some remobilization occurred. However, no TCE bank was formed and TCE did not penetrate into any previously uncontaminated areas. As a result, TCE surface area was increased. Subsequent surfactant floods at higher surfactant concentrations did not trigger more remobilization. TCE was mainly dissolved by the solution with the highest surfactant concentration. Plugging from bacterial growth or microgel formation associated to the polymer at the inflow screen prevented the full completion of the experiment. However, more than 90% of TCE was recovered with the circulation of less than 6 pore volumes of surfactant-polymer solution.
Institute of Scientific and Technical Information of China (English)
李志斌; 陈天华
2002-01-01
An algorithm for constructing exact solitary wave solutions and singular solutions for a class of nonlinear dissipative-dispersive system is presented. With the aid of symbolic manipulation system Maple, some explicit solutions are obtained for the system in physically interesting but non-integrable cases.
Energy Technology Data Exchange (ETDEWEB)
Lavrent' ev, I.V.; Sidorenkov, S.I.
1988-01-01
To establish the limits of applicability of two-dimensional mathematical models describing induced electromagnetic field distribution in an annular MHD channel, it is necessary to solve a three-dimensional problem. By reducing the number of dimensions of the problem (using, for example, the axial symmetry of MHD flow), the solution can be derived in some approximation. This paper proposes and demonstrates this method by studying the motion of a conducting medium in an annular channel with a two-pole ferromagnetic system under various assumptions for the field, channel and liquid, among them the superconductivity of the working medium. The work performed by the Lorentz force in the channel, equal to the Joule losses in the current-carrying boundary layer, was determined. It was concluded that the current-carrying boundary layer begins to develop at the wall of the channel when the flow enters the magnetic field and that its thickness grows with the length of the region of MHD interaction. The problem was solved numerically and asymptotically.
Two-dimensional inflow-wind solution of black hole accretion with an evenly symmetric magnetic field
Mosallanezhad, Amin; Yuan, Feng
2015-01-01
We solve the two-dimensional magnetohydrodynamic (MHD) equations of black hole accretion with the presence of magnetic field. The field includes a turbulent component, whose role is represented by the viscosity, and a large-scale ordered component. The latter is further assumed to be evenly symmetric with the equatorial plane. The equations are solved in the $r-\\theta$ plane of a spherical coordinate by assuming time-steady and radially self-similar. An inflow-wind solution is found. Around the equatorial plane, the gas is inflowing; while above and below the equatorial plane at a certain critical $\\theta$ angle, $\\theta\\sim 47^{\\circ}$, the inflow changes its direction of radial motion and becomes wind. The driving forces are analyzed and found to be the centrifugal force and the gradient of gas and magnetic pressure. The properties of wind are also calculated. The specific angular momentum of wind is found to be significantly larger than that of inflow, thus wind can transfer angular momentum outward. These...
Energy Technology Data Exchange (ETDEWEB)
Setare, M R; Kamali, V, E-mail: rezakord@ipm.ir, E-mail: vkamali1362@gmail.com [Department of Science, Payame Noor University, Bijar (Iran, Islamic Republic of)
2011-11-07
We show that a BTZ black hole solution of cosmological topological massive gravity has a hidden conformal symmetry. In this regard, we consider the wave equation of a massless scalar field propagating in BTZ spacetime and find that the wave equation could be written in terms of the SL(2, R) quadratic Casimir. From the conformal coordinates, the temperatures of the dual conformal field theories (CFTs) could be read directly. Moreover, we compute the microscopic entropy of the dual CFT by the Cardy formula and find a perfect match to the Bekenstein-Hawking entropy of a BTZ black hole. Then, we consider Galilean conformal algebras (GCA), which arises as a contraction of relativistic conformal algebras (x {yields} {epsilon}x, t {yields} t, {epsilon} {yields} 0). We show that there is a correspondence between GCA{sub 2} on the boundary and contracted BTZ in the bulk. For this purpose we obtain the central charges and temperatures of GCA{sub 2}. Then, we compute the microscopic entropy of the GCA{sub 2} by the Cardy formula and find a perfect match to the Bekenstein-Hawking entropy of a BTZ black hole in a non-relativistic limit. The absorption cross section of a near-region scalar field also matches the microscopic absorption cross section of the dual GCA{sub 2}. So we find further evidence that shows correspondence between a contracted BTZ black hole and two-dimensional GCA.
Gorcester, Jeff; Rananavare, Shankar B.; Freed, Jack H.
1989-05-01
Electron spin-echo (ESE) and two-dimensional electron-electron double resonance (2D ELDOR) experiments have been performed as a function of director orientation and temperature in the smectic A phase of the liquid crystal S2 for the spin-probe PD-tempone(2×10-3 M). Over the entire temperature range studied (288-323 K) we observe significant 2D ELDOR cross peaks only for ΔMI =±1 indicative of 14N spin-relaxation and negligible Heisenberg exchange. From the angular dependent 14N spin-relaxation rates we obtain the dipolar spectral densities at the hyperfine (hf) frequency, whereas from a combination of ESE and 2D ELDOR we obtain the dipolar and Zeeman-dipolar spectral densities at zero frequency. The angular dependent spectral densities were successfully decomposed into their basic components in accordance with theory. The angular dependent spectral densities at the hf frequency are not predicted by a model of anisotropic rotational diffusion in a nematic orienting potential, but are consistent with predictions of a model due to Moro and Nordio of solute rototranslational diffusion in a McMillan-type potential. The angular dependence also indicates that order director fluctuations in the smectic phase are suppressed at frequencies on the order of 10 MHz. An additional contribution to solute reorientation due to cooperative hydrocarbon chain fluctuations is suggested to account for the behavior of the observed spectral densities at zero frequency. An evaluation of the relevance of several other dynamical models to this experimental work is also presented.
Lin, Zhaoyang; Yin, Anxiang; Mao, Jun; Xia, Yi; Kempf, Nicholas; He, Qiyuan; Wang, Yiliu; Chen, Chih-Yen; Zhang, Yanliang; Ozolins, Vidvuds; Ren, Zhifeng; Huang, Yu; Duan, Xiangfeng
2016-01-01
Epitaxial heterostructures with precisely controlled composition and electronic modulation are of central importance for electronics, optoelectronics, thermoelectrics, and catalysis. In general, epitaxial material growth requires identical or nearly identical crystal structures with small misfit in lattice symmetry and parameters and is typically achieved by vapor-phase depositions in vacuum. We report a scalable solution-phase growth of symmetry-mismatched PbSe/Bi2Se3 epitaxial heterostructures by using two-dimensional (2D) Bi2Se3 nanoplates as soft templates. The dangling bond–free surface of 2D Bi2Se3 nanoplates guides the growth of PbSe crystal without requiring a one-to-one match in the atomic structure, which exerts minimal restriction on the epitaxial layer. With a layered structure and weak van der Waals interlayer interaction, the interface layer in the 2D Bi2Se3 nanoplates can deform to accommodate incoming layer, thus functioning as a soft template for symmetry-mismatched epitaxial growth of cubic PbSe crystal on rhombohedral Bi2Se3 nanoplates. We show that a solution chemistry approach can be readily used for the synthesis of gram-scale PbSe/Bi2Se3 epitaxial heterostructures, in which the square PbSe (001) layer forms on the trigonal/hexagonal (0001) plane of Bi2Se3 nanoplates. We further show that the resulted PbSe/Bi2Se3 heterostructures can be readily processed into bulk pellet with considerably suppressed thermal conductivity (0.30 W/m·K at room temperature) while retaining respectable electrical conductivity, together delivering a thermoelectric figure of merit ZT three times higher than that of the pristine Bi2Se3 nanoplates at 575 K. Our study demonstrates a unique epitaxy mode enabled by the 2D nanocrystal soft template via an affordable and scalable solution chemistry approach. It opens up new opportunities for the creation of diverse epitaxial heterostructures with highly disparate structures and functions. PMID:27730211
Energy Technology Data Exchange (ETDEWEB)
Hoang-Do, Ngoc-Tram [Department of Physics, Ho Chi Minh City University of Pedagogy 280, An Duong Vuong Street, District 5, Ho Chi Minh City (Viet Nam); Pham, Dang-Lan [Institute for Computational Science and Technology, Quang Trung Software Town, District 12, Ho Chi Minh City (Viet Nam); Le, Van-Hoang, E-mail: hoanglv@hcmup.edu.vn [Department of Physics, Ho Chi Minh City University of Pedagogy 280, An Duong Vuong Street, District 5, Ho Chi Minh City (Viet Nam)
2013-08-15
Exact numerical solutions of the Schrödinger equation for a two-dimensional exciton in a constant magnetic field of arbitrary strength are obtained for not only the ground state but also high excited states. Toward this goal, the operator method is developed by combining with the Levi-Civita transformation which transforms the problem under investigation into that of a two-dimensional anharmonic oscillator. This development of the non-perturbation method is significant because it can be applied to other problems of two-dimensional atomic systems. The obtained energies and wave functions set a new record for their precision of up to 20 decimal places. Analyzing the obtained data we also find an interesting result that exact analytical solutions exist at some values of magnetic field intensity.
Kamataki, K.; Morita, Y.; Shiratani, M.; Koga, K.; Uchida, G.; Itagaki, N.
2012-04-01
We have developed a simple in-situ method for measuring the size distribution (the mean size (mean diameter) and size dispersion) of nano-particles generated in reactive plasmas using the 2 dimensional laser light scattering (2DLLS) method. The principle of the method is based on thermal coagulation of the nano-particles, which occurs after the discharge is turned off, and the size and density of the nano-particles can then be deduced. We first determined the 2D spatial distribution of the density and size of the nano-particles in smaller particle size (a few nm) range than ones deduced from the conventional 2DLLS method. From this 2D dataset, we have for the first time been able to determine the size distribution of nano-particles generated in a reactive plasma without ex-situ measurements.
Energy Technology Data Exchange (ETDEWEB)
Schunert, Sebastian; Azmy, Yousry Y., E-mail: snschune@ncsu.edu, E-mail: yyazmy@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Raleigh, NC (United States)
2011-07-01
The quantification of the discretization error associated with the spatial discretization of the Discrete Ordinate(DO) equations in multidimensional Cartesian geometries is the central problem in error estimation of spatial discretization schemes for transport theory as well as computer code verification. Traditionally ne mesh solutions are employed as reference, because analytical solutions only exist in the absence of scattering. This approach, however, is inadequate when the discretization error associated with the reference solution is not small compared to the discretization error associated with the mesh under scrutiny. Typically this situation occurs if the mesh of interest is only a couple of refinement levels away from the reference solution or if the order of accuracy of the numerical method (and hence the reference as well) is lower than expected. In this work we present a Method of Manufactured Solutions (MMS) benchmark suite with variable order of smoothness of the underlying exact solution for two-dimensional Cartesian geometries which provides analytical solutions aver- aged over arbitrary orthogonal meshes for scattering and non-scattering media. It should be emphasized that the developed MMS benchmark suite rst eliminates the aforementioned limitation of ne mesh reference solutions since it secures knowledge of the underlying true solution and second that it allows for an arbitrary order of smoothness of the underlying ex- act solution. The latter is of importance because even for smooth parameters and boundary conditions the DO equations can feature exact solution with limited smoothness. Moreover, the degree of smoothness is crucial for both the order of accuracy and the magnitude of the discretization error for any spatial discretization scheme. (author)
Energy Technology Data Exchange (ETDEWEB)
Sebastian Schunert; Yousry Y. Azmy
2011-05-01
The quantification of the discretization error associated with the spatial discretization of the Discrete Ordinate(DO) equations in multidimensional Cartesian geometries is the central problem in error estimation of spatial discretization schemes for transport theory as well as computer code verification. Traditionally fine mesh solutions are employed as reference, because analytical solutions only exist in the absence of scattering. This approach, however, is inadequate when the discretization error associated with the reference solution is not small compared to the discretization error associated with the mesh under scrutiny. Typically this situation occurs if the mesh of interest is only a couple of refinement levels away from the reference solution or if the order of accuracy of the numerical method (and hence the reference as well) is lower than expected. In this work we present a Method of Manufactured Solutions (MMS) benchmark suite with variable order of smoothness of the underlying exact solution for two-dimensional Cartesian geometries which provides analytical solutions aver- aged over arbitrary orthogonal meshes for scattering and non-scattering media. It should be emphasized that the developed MMS benchmark suite first eliminates the aforementioned limitation of fine mesh reference solutions since it secures knowledge of the underlying true solution and second that it allows for an arbitrary order of smoothness of the underlying ex- act solution. The latter is of importance because even for smooth parameters and boundary conditions the DO equations can feature exact solution with limited smoothness. Moreover, the degree of smoothness is crucial for both the order of accuracy and the magnitude of the discretization error for any spatial discretization scheme.
Directory of Open Access Journals (Sweden)
Frishter Ljudmila Jur'evna
2012-10-01
Full Text Available The article represents the results of the evaluation of the strain-stress distribution in the area of concentrated tensions in the two-dimensional angle-shaped area of the border. Solutions to the nonsingular homogeneous two-dimensional elastic problem may be evaluated through their extrapolation onto sections located in the vicinity of an irregular point of the border by taking the account of the experimental data and the practical accuracy of measurements taken through the application of the photoelasticity method.
Salas, J; Ayora, C
2004-03-01
The stability of uranium-bearing minerals in natural environments is of interest to evaluate the feasibility of radioactive waste repositories. The uraninite bodies, UO2(s), in the Oklo district (Gabon) are the result of a natural fission process, which took place 1970 Ma ago. These deposits can be regarded as natural analogues for spent fuel. One of the uraninite bodies, the Okélobondo deposit, is located at a depth of 300 m. Groundwater samples from boreholes located at shallow depths (100-200 m) show neutral to basic pH, anoxic conditions (Eh = 0.10 to -0.05 V) and are saturated with respect to uraninite. In contrast, deeper samples collected in the vicinity of the ore body are oxidising (Eh = 0.32-0.47 V), slightly basic (pH = 7.0-8.5) and undersaturated with respect to uraninite. These oxidising conditions at depth, if present under repository conditions, may affect the stability of uranium oxide. In order to improve our understanding of the observed site geochemistry, the available information on the lithology and groundwater flow was integrated in a reactive transport model. The chemical composition and the pH-Eh values of the water sampled above and in the western side of the Okélobondo deposit can be explained by the interaction of meteoric recharge with pelites, dolomites and sandstones. The dissolution of Fe(II)-silicates and the oxidation of the Fe(II)-aqueous species maintained the pH-Eh distribution along the Fe(2+)-Fe(OH)3(am) equilibrium, with the result that uraninite does not dissolve. This may explain the lower uranium content in the water samples from pelites and dolomites above the Okélobondo deposit. The high Mn/Fe ratio and the high pH-Eh values of the water sampled at depth, close to the Okélobondo deposit, suggest a control by the Mn(2+)-MnOOH(s) equilibrium. This control is attributed to the dissolution of a large rhodochrosite, MnCO3(s), and manganite, MnOOH(s) deposit in the recharge area on the eastern side.
Salas, J.; Ayora, C.
2004-03-01
The stability of uranium-bearing minerals in natural environments is of interest to evaluate the feasibility of radioactive waste repositories. The uraninite bodies, UO 2(s), in the Oklo district (Gabon) are the result of a natural fission process, which took place 1970 Ma ago. These deposits can be regarded as natural analogues for spent fuel. One of the uraninite bodies, the Okélobondo deposit, is located at a depth of 300 m. Groundwater samples from boreholes located at shallow depths (100-200 m) show neutral to basic pH, anoxic conditions (Eh=0.10 to -0.05 V) and are saturated with respect to uraninite. In contrast, deeper samples collected in the vicinity of the ore body are oxidising (Eh=0.32-0.47 V), slightly basic (pH=7.0-8.5) and undersaturated with respect to uraninite. These oxidising conditions at depth, if present under repository conditions, may affect the stability of uranium oxide. In order to improve our understanding of the observed site geochemistry, the available information on the lithology and groundwater flow was integrated in a reactive transport model. The chemical composition and the pH-Eh values of the water sampled above and in the western side of the Okélobondo deposit can be explained by the interaction of meteoric recharge with pelites, dolomites and sandstones. The dissolution of Fe(II)-silicates and the oxidation of the Fe(II)-aqueous species maintained the pH-Eh distribution along the Fe 2+-Fe(OH) 3(am) equilibrium, with the result that uraninite does not dissolve. This may explain the lower uranium content in the water samples from pelites and dolomites above the Okélobondo deposit. The high Mn/Fe ratio and the high pH-Eh values of the water sampled at depth, close to the Okélobondo deposit, suggest a control by the Mn 2+-MnOOH(s) equilibrium. This control is attributed to the dissolution of a large rhodochrosite, MnCO 3(s), and manganite, MnOOH(s) deposit in the recharge area on the eastern side.
Energy Technology Data Exchange (ETDEWEB)
Sawyer, Karma Rae [Univ. of California, Berkeley, CA (United States)
2008-12-01
Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.
Energy Technology Data Exchange (ETDEWEB)
Filho, J. F. P. [Institute de Matematica, Estatistica e Fisica, Universidade Federal do Rio Grande, Av. Italia, s/n, 96203-900 Rio Grande, RS (Brazil); Barichello, L. B. [Institute de Matematica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves, 9500, 91509-900 Porto Alegre, RS (Brazil)
2013-07-01
In this work, an analytical discrete ordinates method is used to solve a nodal formulation of a neutron transport problem in x, y-geometry. The proposed approach leads to an important reduction in the order of the associated eigenvalue systems, when combined with the classical level symmetric quadrature scheme. Auxiliary equations are proposed, as usually required for nodal methods, to express the unknown fluxes at the boundary introduced as additional unknowns in the integrated equations. Numerical results, for the problem defined by a two-dimensional region with a spatially constant and isotropically emitting source, are presented and compared with those available in the literature. (authors)
Institute of Scientific and Technical Information of China (English)
宋丽娜; 王维国
2012-01-01
By constructing the iterative formula with a so-called convergence-control parameter, the generalized two-dimensional differential transform method is improved. With the enhanced technique, the nonlinear fractional Kolmogorov-Petrovskii-Piskunov equations are dealt analytically and approximate solutions are derived. The results show that the employed approach is a promising tool for solving many nonlinear fractional partial differential equations. The algorithm described in this work is expected to be employed to solve more problems in fractional calculus.
Song, Li-Na; Wang, Wei-Guo
2012-08-01
By constructing the iterative formula with a so-called convergence-control parameter, the generalized two-dimensional differential transform method is improved. With the enhanced technique, the nonlinear fractional Kolmogorov-Petrovskii-Piskunov equations are dealt analytically and approximate solutions are derived. The results show that the employed approach is a promising tool for solving many nonlinear fractional partial differential equations. The algorithm described in this work is expected to be employed to solve more problems in fractional calculus.
A Finite-Element Solution of the Navier-Stokes Equations for Two-Dimensional and Axis-Symmetric Flow
Directory of Open Access Journals (Sweden)
Sven Ø. Wille
1980-04-01
Full Text Available The finite element formulation of the Navier-Stokes equations is derived for two-dimensional and axis-symmetric flow. The simple triangular, T6, isoparametric element is used. The velocities are interpolated by quadratic polynomials and the pressure is interpolated by linear polynomials. The non-linear simultaneous equations are solved iteratively by the Newton-Raphson method and the element matrix is given in the Newton-Raphson form. The finite element domain is organized in substructures and an equation solver which works on each substructure is specially designed. This equation solver needs less storage in the computer and is faster than the traditional banded equation solver. To reduce the amount of input data an automatic mesh generator is designed. The input consists of the coordinates of eight points defining each substructure with the corresponding boundary conditions. In order to interpret the results they are plotted on a calcomp plotter. Examples of plots of the velocities, the streamlines and the pressure inside a two-dimensional flow divider and an axis-symmetric expansion of a tube are shown for various Reynolds numbers.
LeBlanc, J. P. F.; Antipov, Andrey E.; Becca, Federico; Bulik, Ireneusz W.; Chan, Garnet Kin-Lic; Chung, Chia-Min; Deng, Youjin; Ferrero, Michel; Henderson, Thomas M.; Jiménez-Hoyos, Carlos A.; Kozik, E.; Liu, Xuan-Wen; Millis, Andrew J.; Prokof'ev, N. V.; Qin, Mingpu; Scuseria, Gustavo E.; Shi, Hao; Svistunov, B. V.; Tocchio, Luca F.; Tupitsyn, I. S.; White, Steven R.; Zhang, Shiwei; Zheng, Bo-Xiao; Zhu, Zhenyue; Gull, Emanuel; Simons Collaboration on the Many-Electron Problem
2015-10-01
Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies) of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.
Leblanc, James
In this talk we present numerical results for ground state and excited state properties (energies, double occupancies, and Matsubara-axis self energies) of the single-orbital Hubbard model on a two-dimensional square lattice. In order to provide an assessment of our ability to compute accurate results in the thermodynamic limit we employ numerous methods including auxiliary field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock. We illustrate cases where agreement between different methods is obtained in order to establish benchmark results that should be useful in the validation of future results.
Directory of Open Access Journals (Sweden)
2015-12-01
Full Text Available Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.
Energy Technology Data Exchange (ETDEWEB)
Maita, S.; Ando, J.; Nakatake, K. [Kyushu University, Fukuoka (Japan). Faculty of Engineering
1996-10-01
A simple panel method, the source and quasi continuous vortex lattice method (SQCM) was expanded to two-dimensional non-steady hydrofoil problems. Discussions were given on the results of calculations on two-dimensional hydrofoils making a simple non-steady motion. In calculating hydrofoils which move suddenly from a still state with angle of elevation {alpha} at a velocity U, the following results were obtained: the time differential item in a pressure equation gives a considerably strong effect on lifting power; and the lifting power converges to a steady state with lapse of time, and the lifting power coefficient in that state shows that the lifting power increases as hydrofoil thickness increases. This result agrees with the hydrofoil thickness effect in the two-dimensional steady problem, proving the reasonability of this calculation method. In the calculations of time history of the lifting power acting on hydrofoils passing a sinusoidal gust and hydrofoils in a pitching motion, the calculated values from the SQCM were found to approach analysis solution to thin hydrofoils as the hydrofoil thickness becomes thinner for both cases. This result also proves the result of calculations on non-steady state by using the SQCM reasonable. 11 refs., 10 figs.
Ross, Matthew R.
The primary focus of this work is the development of a mid-infrared pulse shaping system. The primary motivation for this system is for two-dimensional infrared (2DIR) spectroscopy, however, the mid-infrared pulse shaper also allows for more sophisticated spectroscopic experiments not previously attempted in the mid-infrared. Moreover, many can be implemented without changes or realignment of the optical setup. Example spectra are presented along with a discussion of capabilities and diagnostics. A second major project presented is 2DIR spectroscopy of iron pentacarbonyl, Fe(CO)5, a small metal carbonyl. This molecule undergoes Berry pseudorotation, a form of fluxtionality. This fast exchange of ligands mixes axial and equatorial modes and occurs on a timescale of picoseconds, too fast for NMR and other methods of measuring chemical structure and isomerization. Ultrafast chemical exchange spectroscopy, a measurement within 2DIR spectroscopy, is capable of resolving the time scales of this motion. We found that this process is affected by the solvent environment, specifically the solvent viscosity in alkanes and hydrogen bonding environments in alcohols. Lastly, a study is presented in which a series of synthetic metalloenzymes with a metal active site are studied by 2DIR spectroscopy. In this case a carbonyl is ligated to a copper-I atom in the active site, which then serves as our spectroscopic probe. We find, unexpectedly, that the shape of the carbonyl vibrational potential, as measured by the anharmonicity, is time-dependent. We attribute this to a geometrical rearrangement and are able to suggest that this effect is dependent on local site structure and dynamics and not significantly affected by electric potential near the peptide.
Hirose, S; Tanuma, S; Shibata, K; Takahashi, M; Tanigawa, T; Sasaqui, T; Noro, A; Uehara, K; Takahashi, K; Taniguchi, T
2003-01-01
The Kelvin-Helmholtz (KH) and tearing instabilities are likely to be important for the process of fast magnetic reconnection that is believed to explain the observed explosive energy release in solar flares. Theoretical studies of the instabilities, however, typically invoke simplified initial magnetic and velocity fields that are not solutions of the governing magnetohydrodynamic (MHD) equations. In the present study, the stability of a reconnecting current sheet is examined using a class of exact global MHD solutions for steady state incompressible magnetic reconnection (Craig & Henton 1995). Numerical simulation indicates that the outflow solutions where the current sheet is formed by strong shearing flows are subject to the KH instability. The inflow solutions where a fast and weakly sheared inflow leads to a strong magnetic field pile-up at the entrance to the sheet are shown to be tearing unstable. Although the observed instability of the solutions can be interpreted qualitatively by applying standa...
Directory of Open Access Journals (Sweden)
Puskar Raj SHARMA
2012-01-01
Full Text Available Aim of the paper is to investigate solution of twodimensional linear parabolic partial differential equation with non-local boundary conditions using Homotopy Perturbation Method (HPM. This method is not only reliable in obtaining solution of such problems in series form with high accuracy but it also guarantees considerable saving of the calculation volume and time as compared to other methods. The application of the method has been illustrated through an example
Fujie, Kentarou; Senba, Takasi
2016-08-01
This paper deals with positive radially symmetric solutions of the Neumann boundary value problem for the fully parabolic chemotaxis system, {ut=Δu-∇ṡ(u∇χ(v))in Ω×(0,∞),τvt=Δv-v+uin Ω×(0,∞), in a ball Ω \\subset {{{R}}2} with general sensitivity function χ (v) satisfying {χ\\prime}>0 and decaying property {χ\\prime}(s)\\to 0 (s\\to ∞ ), parameter τ \\in ≤ft(0,1\\right] and nonnegative radially symmetric initial data. It is shown that if τ \\in ≤ft(0,1\\right] is sufficiently small, then the problem has a unique classical radially symmetric solution, which exists globally and remains uniformly bounded in time. Especially, this result establishes global existence of solutions in the case χ (v)={χ0}log v for all {χ0}>0 , which has been left as an open problem.
Bloem, Robbert; Dijkstra, Arend G.; Jansen, Thomas La Cour; Knoester, Jasper
2008-01-01
Population transfer between vibrational eigenstates is important for many phenomena in chemistry. In solution, this transfer is induced by fluctuations in molecular conformation as well as in the surrounding solvent. We develop a joint electrostatic density functional theory map that allows us to co
Directory of Open Access Journals (Sweden)
Lulu Deng
2011-07-01
Full Text Available The phase and texture of a newly developed solution-processed copper phthalocyanine (CuPc thin film have been investigated by two-dimensional grazing incidence X-ray diffraction. The results show that it has β phase crystalline structure, with crystallinity greater than 80%. The average size of the crystallites is found to be about 24 nm. There are two different arrangements of crystallites, with one dominating the diffraction pattern. Both of them have preferred orientation along the thin film normal. Based on the similarities to the vacuum deposited CuPc thin films, the new solution processing method is verified to offer a good alternative to vacuum process, for the fabrication of low cost small molecule based organic photovoltaics.
Institute of Scientific and Technical Information of China (English)
Ying-hui ZHANG; Zhong TAN
2011-01-01
In this paper,we are concerned with the asymptotic behaviour of a weak solution to the NavierStokes equations for compressible barotropic flow in two space dimensions with the pressure function satisfying p(ρ) =a(ρ)logd(ρ) for large (ρ).Here d ＞ 2,a ＞ 0.We introduce useful tools from the theory of Orlicz spaces and construct a suitable function which approximates the density for time going to infinity.Using properties of this function,we can prove the strong convergence of the density to its limit state.The behaviour of the velocity field and kinetic energy is also briefly discussed.
Classical Solution of a Two-Dimensional Dynamics System for Pure Forest%一个二维纯林发展系统的古典解
Institute of Scientific and Technical Information of China (English)
徐龙封; 吴慧
2011-01-01
The research of two-dimensional forest dynamics system model is still open. First, for the peculiarity of two-dimensional forest dynamics systems with initial state depending only on total quantity of forest, and boundary condition depending only on initial state again, boundary of system not satisfying one of 3 kinds common conditions, by introducing a class of special family curves in presence region of " stand age-diameter", the problem of boundary conditions is avoided. Secondly, using the technique of selecting measure dimension of lumber diameter properly, a well-posed two-dimensional forest dynamics system model is propounded. At last, colligating the technique of pulling characteristic curve, a prior estimate, structuring integral equation of initial state, iteration, the existence and uniqueness of the global classical solution are proved for this system.%二维森林发展系统模型的研究还未见到任何结果.针对这类系统初始状态依赖于林木总量,而边界状态又依赖于初始状态,系统的边界不满足通常的三类条件之一的特点,采用在“树龄-直径”存在区域内引进一类特殊的曲线族,避开了提边界条件问题.再利用适当地选择林木直径尺度量纲的技巧,提出了一个适定的二维纯林发展系统模型,最后综合拉特征线、先验估计、构造初始状态积分方程、迭代等技巧证明了这个系统整体古典解的存在唯一性.
Lansing, F. L.
1980-01-01
A numerical procedure was established using the finite-difference technique in the determination of the time-varying temperature distribution of a tubular solar collector under changing solar radiancy and ambient temperature. Three types of spatial discretization processes were considered and compared for their accuracy of computations and for selection of the shortest computer time and cost. The stability criteria of this technique were analyzed in detail to give the critical time increment to ensure stable computations. The results of the numerical analysis were in good agreement with the analytical solution previously reported. The numerical method proved to be a powerful tool in the investigation of the collector sensitivity to two different flow patterns and several flow control mechanisms.
Energy Technology Data Exchange (ETDEWEB)
Kravchenko, Vladislav V [Seccion de Posgrado e Investigacion, Escuela Superior de IngenierIa Mecanica y Electrica, Instituto Politecnico Nacional, C.P.07738 Mexico DF (Mexico)
2005-05-06
We consider the real stationary two-dimensional Schroedinger equation. With the aid of any of its particular solutions, we construct a Vekua equation possessing the following special property. The real parts of its solutions are solutions of the original Schroedinger equation and the imaginary parts are solutions of an associated Schroedinger equation with a potential having the form of a potential obtained after the Darboux transformation. Using Bers' theory of Taylor series for pseudoanalytic functions, we obtain a locally complete system of solutions of the original Schroedinger equation which can be constructed explicitly for an ample class of Schroedinger equations. For example it is possible when the potential is a function of one Cartesian, spherical, parabolic or elliptic variable. We give some examples of application of the proposed procedure for obtaining a locally complete system of solutions of the Schroedinger equation. The procedure is algorithmically simple and can be implemented with the aid of a computer system of symbolic or numerical calculation.
Energy Technology Data Exchange (ETDEWEB)
Prinja, A.K.
1998-09-01
In this work, it has been shown that, for the given sets of parameters (transport coefficients), the Tangent-Predictor (TP) continuation method, which was used in the coarsest grid, works remarkably well. The problems in finding an initial guess that resides well within Newton`s method radius of convergence are alleviated by correcting the initial guess by the predictor step of the TP method. The TP method works well also in neutral gas puffing and impurity simulations. The neutral gas puffing simulation is performed by systematically increasing the fraction of puffing rate according to the TP method until it reaches a desired condition. Similarly, the impurity simulation characterized by using the fraction of impurity density as the continuation parameter, is carried out in line with the TP method. Both methods show, as expected, a better performance than the classical embedding (CE) method. The convergence criteria {epsilon} is set to be 10{sup {minus}9} based on the fact that lower value of {epsilon} does not alter the solution significantly. Correspondingly, the number of Newton`s iterations in the corrector step of the TP method decrease substantially, an extra point in terms of code speed. The success of the TP method enlarges the possibility of including other sets of parameters (operations and physics). With the availability of the converged coarsest grid solution, the next forward step to the multigrid cycle becomes possible. The multigrid method shows that the memory storage problems that plagued the application of Newton`s method on fine grids, are of no concern. An important result that needs to be noted here is the performance of the FFCD model. The FFCD model is relatively simple and is based on the overall results the model has shown to predict different divertor plasma parameters. The FFCD model treats exactly the implementation of the deep penetration of energetic neutrals emerging from the divertor plate. The resulting ionization profiles are
Carling; Williams; Bowtell
1998-12-01
Anguilliform swimming has been investigated by using a computational model combining the dynamics of both the creature's movement and the two-dimensional fluid flow of the surrounding water. The model creature is self-propelled; it follows a path determined by the forces acting upon it, as generated by its prescribed changing shape. The numerical solution has been obtained by applying coordinate transformations and then using finite difference methods. Results are presented showing the flow around the creature as it accelerates from rest in an enclosed tank. The kinematics and dynamics associated with the creature's centre of mass are also shown. For a particular set of body shape parameters, the final mean swimming speed is found to be 0.77 times the speed of the backward-travelling wave. The corresponding movement amplitude envelope is shown. The magnitude of oscillation in the net forward force has been shown to be approximately twice that in the lateral force. The importance of allowing for acceleration and deceleration of the creature's body (rather than imposing a constant swimming speed) has been demonstrated. The calculations of rotational movement of the body and the associated moment of forces about the centre of mass have also been included in the model. The important role of viscous forces along and around the creature's body and in the growth and dissolution of the vortex structures has been illustrated.
Osserman, Robert
2011-01-01
The basic component of several-variable calculus, two-dimensional calculus is vital to mastery of the broader field. This extensive treatment of the subject offers the advantage of a thorough integration of linear algebra and materials, which aids readers in the development of geometric intuition. An introductory chapter presents background information on vectors in the plane, plane curves, and functions of two variables. Subsequent chapters address differentiation, transformations, and integration. Each chapter concludes with problem sets, and answers to selected exercises appear at the end o
Juday, Richard D. (Inventor)
1992-01-01
A two-dimensional vernier scale is disclosed utilizing a cartesian grid on one plate member with a polar grid on an overlying transparent plate member. The polar grid has multiple concentric circles at a fractional spacing of the spacing of the cartesian grid lines. By locating the center of the polar grid on a location on the cartesian grid, interpolation can be made of both the X and Y fractional relationship to the cartesian grid by noting which circles coincide with a cartesian grid line for the X and Y direction.
Boumali, Abdelmalek
2016-01-01
In this paper, the problem of a two-dimensional Duffin-Petiau-Kemmer (DKP) oscillator in the presence of a coulomb potential in the cosmic string background is solved. The eigensolutions of the problem in question have been found, and the influence of the cosmic string space-time on the eigenvalues has been analyzed.
Two-dimensional optical spectroscopy
Cho, Minhaeng
2009-01-01
Discusses the principles and applications of two-dimensional vibrational and optical spectroscopy techniques. This book provides an account of basic theory required for an understanding of two-dimensional vibrational and electronic spectroscopy.
Two-dimensional capillary origami
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Brubaker, N.D., E-mail: nbrubaker@math.arizona.edu; Lega, J., E-mail: lega@math.arizona.edu
2016-01-08
We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.
Nonacid Reactive Solution for deep well stimulation
Energy Technology Data Exchange (ETDEWEB)
Pendergrass, J.; Bell, D.; Bishop, D.; Campbell, P.; Copeland, J.
1984-04-01
Certain formations in the Anardarko Basin have not responded well to acid-base cleanup or breakdown treatments. The use of a Nonacid Reactive Solution (NARS) for deep wells where both formation sensitivity and excessive corrosion of tubular goods present problems can produce improved well response. Laboratory analyses of the Morrow, Red Fork and Springer formations in the Anadarko Basin justify the use of NARS for stimulation treatments in these formations. Laboratory data and production results demonstrate that NARS can be used as an economical and effective method of mud removal in wells which are drilled with oil-base mud. Further studies investigate the effect of NARS on downhole tubular goods. Well histories in the three formations support the effectiveness of the fluid, and the variety of treatment designs dictated by the diverse formation characteristics demonstrates the versatility of NARS. By concentrating the study of rock lithologies, core and laboratory analyses, and production results, NARS can be used in breakdown and cleanup treatments more effectively than acid-base fluids in sensitive formations.
Golbabai, Ahmad; Nikpour, Ahmad
2016-10-01
In this paper, two-dimensional Schrödinger equations are solved by differential quadrature method. Key point in this method is the determination of the weight coefficients for approximation of spatial derivatives. Multiquadric (MQ) radial basis function is applied as test functions to compute these weight coefficients. Unlike traditional DQ methods, which were originally defined on meshes of node points, the RBFDQ method requires no mesh-connectivity information and allows straightforward implementation in an unstructured nodes. Moreover, the calculation of coefficients using MQ function includes a shape parameter c. A new variable shape parameter is introduced and its effect on the accuracy and stability of the method is studied. We perform an analysis for the dispersion error and different internal parameters of the algorithm are studied in order to examine the behavior of this error. Numerical examples show that MQDQ method can efficiently approximate problems in complexly shaped domains.
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Soylu, A. [Department of Physics, Faculty of Arts and Sciences, Erciyes University, Kayseri (Turkey) and Department of Physics, Faculty of Arts and Sciences, Nigde University, Nigde (Turkey)]. E-mail: asimsoylu@gmail.com; Boztosun, I. [Department of Physics, Faculty of Arts and Sciences, Erciyes University, Kayseri (Turkey)
2007-06-15
In this paper, we present the energy eigenvalues of a two-dimensional hydrogenic donor in a magnetic field by using the asymptotic iteration method. The binding energy eigenvalues in the presence of weak and strong magnetic fields ({gamma}<>0) are obtained within the framework of this iterative approach for 1S, 2P{sup -} and 3D{sup -} levels. The energy eigenvalues for the non-magnetic field case ({gamma}=0) are also determined and the results are compared with the values in weak and strong magnetic fields. The effect of the magnetic field strength on the energy eigenvalues are determined explicitly and excellent agreement with the findings of other methods is obtained.
Two-Dimensional Toda-Heisenberg Lattice
Directory of Open Access Journals (Sweden)
Vadim E. Vekslerchik
2013-06-01
Full Text Available We consider a nonlinear model that is a combination of the anisotropic two-dimensional classical Heisenberg and Toda-like lattices. In the framework of the Hirota direct approach, we present the field equations of this model as a bilinear system, which is closely related to the Ablowitz-Ladik hierarchy, and derive its N-soliton solutions.
Energy Technology Data Exchange (ETDEWEB)
Monsefi, Farid [Division of Applied Mathematics, The School of Education, Culture and Communication, Mälardalen University, MDH, Västerås, Sweden and School of Innovation, Design and Engineering, IDT, Mälardalen University, MDH Väs (Sweden); Carlsson, Linus; Silvestrov, Sergei [Division of Applied Mathematics, The School of Education, Culture and Communication, Mälardalen University, MDH, Västerås (Sweden); Rančić, Milica [Division of Applied Mathematics, The School of Education, Culture and Communication, Mälardalen University, MDH, Västerås, Sweden and Department of Theoretical Electrical Engineering, Faculty of Electronic Engineering, University (Serbia); Otterskog, Magnus [School of Innovation, Design and Engineering, IDT, Mälardalen University, MDH Västerås (Sweden)
2014-12-10
To solve the electromagnetic scattering problem in two dimensions, the Finite Difference Time Domain (FDTD) method is used. The order of convergence of the FDTD algorithm, solving the two-dimensional Maxwell’s curl equations, is estimated in two different computer implementations: with and without an obstacle in the numerical domain of the FDTD scheme. This constitutes an electromagnetic scattering problem where a lumped sinusoidal current source, as a source of electromagnetic radiation, is included inside the boundary. Confined within the boundary, a specific kind of Absorbing Boundary Condition (ABC) is chosen and the outside of the boundary is in form of a Perfect Electric Conducting (PEC) surface. Inserted in the computer implementation, a semi-norm has been applied to compare different step sizes in the FDTD scheme. First, the domain of the problem is chosen to be the free-space without any obstacles. In the second part of the computer implementations, a PEC surface is included as the obstacle. The numerical instability of the algorithms can be rather easily avoided with respect to the Courant stability condition, which is frequently used in applying the general FDTD algorithm.
Directory of Open Access Journals (Sweden)
Jorge Rodolfo Silva Zabadal
2006-06-01
Full Text Available Neste trabalho são apresentados métodos híbridos para solução de problemas difusivos relativos à dispersão de poluentes em meio aquático. Estes métodos aplicam variáveis complexas a fim de executar mapeamentos sobre a equação diferencial a ser resolvida bem como sobre o domínio considerado. O mapeamento sobre a equação diferencial converte o operador laplaciano bidimensional em uma derivada cruzada de segunda ordem na variável espacial. O mapeamento do domínio transforma regiões de formato complexo em regiões retangulares. Ambos mapeamentos são usados a fim de reduzir o tempo total requerido de processamento para solução de problemas difusivos não-homogêneos. Resultados numéricos são apresentados.In this work hybrid methods for solving diffusion problems related to pollutants dispersion in water bodies are presented. These methods employ complex variables in order to perform mappings over the differential equation to be solved as well as over the considered domain. The mapping over the differential equation converts the two dimensional laplacian operator into a second order mixed derivative in the complex variables. The mapping of the domain transforms complex-shaped regions into rectangular ones. Both mappings are used in order to reduce the total time proccessing required for solving non-homogeneous diffusion problems. Numerical results are reported.
Barrett, John W.; Süli, Endre
2016-07-01
We prove the existence of global-in-time weak solutions to a general class of models that arise from the kinetic theory of dilute solutions of nonhomogeneous polymeric liquids, where the polymer molecules are idealized as bead-spring chains with finitely extensible nonlinear elastic (FENE) type spring potentials. The class of models under consideration involves the unsteady, compressible, isentropic, isothermal Navier-Stokes system in a bounded domain Ω in Rd, d = 2, for the density ρ, the velocity u ˜ and the pressure p of the fluid, with an equation of state of the form p (ρ) =cpργ, where cp is a positive constant and γ > 1. The right-hand side of the Navier-Stokes momentum equation includes an elastic extra-stress tensor, which is the classical Kramers expression. The elastic extra-stress tensor stems from the random movement of the polymer chains and is defined through the associated probability density function that satisfies a Fokker-Planck-type parabolic equation, a crucial feature of which is the presence of a centre-of-mass diffusion term. This extends the result in our paper J.W. Barrett and E. Süli (2016) [9], which established the existence of global-in-time weak solutions to the system for d ∈ { 2 , 3 } and γ >3/2, but the elastic extra-stress tensor required there the addition of a quadratic interaction term to the classical Kramers expression to complete the compactness argument on which the proof was based. We show here that in the case of d = 2 and γ > 1 the existence of global-in-time weak solutions can be proved in the absence of the quadratic interaction term. Our results require no structural assumptions on the drag term in the Fokker-Planck equation; in particular, the drag term need not be corotational. With a nonnegative initial density ρ0 ∈L∞ (Ω) for the continuity equation; a square-integrable initial velocity datum u˜0 for the Navier-Stokes momentum equation; and a nonnegative initial probability density function ψ0
Vermeiren, Koen
2005-08-26
Since years, ion exclusion chromatography (ICE) has been the standard method to separate strong acid analyte anions from concentrated weak acid matrices such as hydrofluoric acid (HF). In this work, the commercially available IonPac ICE-AS 1 column was used to separate trace levels of chloride, nitrate, sulfate and phosphate from HF solutions at 20% (w/w). The efficiency of the separation was studied in more detail using techniques such as ion chromatography (IC), inductively coupled plasma optical emission spectrometry (ICP-OES) and ICP-mass spectrometry (ICP-MS). For 20% (w/w) HF solutions and at a water carrier flow-rate of 0.50 ml/min, the cut window was set from 8.5 to 14.5 min. Under these conditions, analyte recoveries of better than 90% were obtained for chloride, nitrate and sulfate, but only about 75% for phosphate. The HF rejection efficiency was better than 99.9%. It was found that the ICP techniques, measuring total element levels and not species, yielded significantly higher recoveries for phosphorus and sulfur compared to IC. Evidence will be given that part of the added phosphorus (approximately 15% for an addition of 10 mg PO4/kg) is present as mono-fluorophosphoric acid (H2FPO3). In the case of sulfate, the difference between IC and ICP-MS could be attributed to an important matrix effect from the residual HF concentration.
Messaris, G. T.; Papastavrou, C. A.; Loukopoulos, V. C.; Karahalios, G. T.
2009-08-01
A new finite-difference method is presented for the numerical solution of the Navier-Stokes equations of motion of a viscous incompressible fluid in two (or three) dimensions and in the primitive-variable formulation. Introducing two auxiliary functions of the coordinate system and considering the form of the initial equation on lines passing through the nodal point (x0, y0) and parallel to the coordinate axes, we can separate it into two parts that are finally reduced to ordinary differential equations, one for each dimension. The final system of linear equations in n-unknowns is solved by an iterative technique and the method converges rapidly giving satisfactory results. For the pressure variable we consider a pressure Poisson equation with suitable Neumann boundary conditions. Numerical results, confirming the accuracy of the proposed method, are presented for configurations of interest, like Poiseuille flow and the flow between two parallel plates with step under the presence of a pressure gradient.
Directory of Open Access Journals (Sweden)
Claudio Fontanesi
2010-03-01
Full Text Available The adsorption of anthracene (C14H10, at the mercury electrode/ethylene glycol (EG solution interface, is characterized by a low and almost constant capacity (about 8 μF cm−2 region (capacitive “pit” or “plateau” in capacity vs. potential curves, upon selection of suitable values of temperature, bulk concentration and applied potential values. This result is rationalized assuming the occurrence of a 2D phase transition between two distinct adsorbed phases: (i a “disordered” phase, characterized by a flat “parallel” disposition of the aromatic moiety on the electrode surface (ii an “ordered” phase, characterized by a “perpendicular” disposition of the aromatic moiety on the electrode surface. The experimental evidence is rationalized by considering the chemical potential as an explicit function of the “electric field/adsorbed molecule” interaction. Such a modelistic approach enables the determination of the relevant standard entropy variation.
Two-dimensional liquid chromatography
DEFF Research Database (Denmark)
Græsbøll, Rune
of this thesis is on online comprehensive two-dimensional liquid chromatography (online LC×LC) with reverse phase in both dimensions (online RP×RP). Since online RP×RP has not been attempted before within this research group, a significant part of this thesis consists of knowledge and experience gained...
Chang, Sin-Chung; Wang, Xiao-Yen; Chow, Chuen-Yen
1994-01-01
A new numerical discretization method for solving conservation laws is being developed. This new approach differs substantially in both concept and methodology from the well-established methods, i.e., finite difference, finite volume, finite element, and spectral methods. It is motivated by several important physical/numerical considerations and designed to avoid several key limitations of the above traditional methods. As a result of the above considerations, a set of key principles for the design of numerical schemes was put forth in a previous report. These principles were used to construct several numerical schemes that model a 1-D time-dependent convection-diffusion equation. These schemes were then extended to solve the time-dependent Euler and Navier-Stokes equations of a perfect gas. It was shown that the above schemes compared favorably with the traditional schemes in simplicity, generality, and accuracy. In this report, the 2-D versions of the above schemes, except the Navier-Stokes solver, are constructed using the same set of design principles. Their constructions are simplified greatly by the use of a nontraditional space-time mesh. Its use results in the simplest stencil possible, i.e., a tetrahedron in a 3-D space-time with a vertex at the upper time level and other three at the lower time level. Because of the similarity in their design, each of the present 2-D solvers virtually shares with its 1-D counterpart the same fundamental characteristics. Moreover, it is shown that the present Euler solver is capable of generating highly accurate solutions for a famous 2-D shock reflection problem. Specifically, both the incident and the reflected shocks can be resolved by a single data point without the presence of numerical oscillations near the discontinuity.
The characters of nonlinear vibration in the two-dimensional discrete monoatomic lattice
Institute of Scientific and Technical Information of China (English)
XU Quan; TIAN Qiang
2005-01-01
The two-dimensional discrete monoatomic lattice is analyzed. Taking nearest-neighbor interaction into account, the characters of the nonlinear vibration in two-dimensional discrete monoatomic lattice are described by the two-dimensional cubic nonlinear Schrodinger equation. Considering the quartic nonlinear potential, the two-dimensional discrete-soliton trains and the solutions perturbed by the neck mode are presented.
Two dimensional unstable scar statistics.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Kotulski, Joseph Daniel; Lee, Kelvin S. H. (ITT Industries/AES Los Angeles, CA)
2006-12-01
This report examines the localization of time harmonic high frequency modal fields in two dimensional cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This paper examines the enhancements for these unstable orbits when the opposing mirrors are both convex and concave. In the latter case the construction includes the treatment of interior foci.
Juday, Richard D.
1992-01-01
Modified vernier scale gives accurate two-dimensional coordinates from maps, drawings, or cathode-ray-tube displays. Movable circular overlay rests on fixed rectangular-grid overlay. Pitch of circles nine-tenths that of grid and, for greatest accuracy, radii of circles large compared with pitch of grid. Scale enables user to interpolate between finest divisions of regularly spaced rule simply by observing which mark on auxiliary vernier rule aligns with mark on primary rule.
Chen, Jui-Sheng; Hsu, Shao-Yiu; Li, Ming-Hsu; Liu, Chen-Wuing
2016-12-01
Transport behavior through a permeable reactive barrier (PRB)-aquifer system is complicated because of the different physical and chemical properties of the PRB and the aquifer. Dual-domain solute transport models are efficient tools for better understanding the various processes and mechanisms of reactive solute transport through a PRB-aquifer system. This study develops a dual-domain analytical model to assess the physical and chemical processes of two-dimensional reactive solute transport through a PRB-aquifer system. The dispersion processes of a dual-domain system on the solute transport are investigated. The results show that the dispersion parameters in a dual-domain system synchronously govern the dynamic shape of the contaminant plume. The low longitudinal and transverse dispersion coefficients of a dual-domain system may restrict the spreading of the plume and elevate the plume's concentration level. The derived analytical solution is applied to explore how the different reactive transport processes affect the performance of a PRB-aquifer system. The results show that the first-order decay rate constant of the PRB has a critical effect on the performance of the PRB-aquifer system, whereas the effects of the physical dispersion properties on PRB performance are less significant.
End-Member Formulation of Solid Solutions and Reactive Transport
Energy Technology Data Exchange (ETDEWEB)
Lichtner, Peter C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-09-01
A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.
Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions
Kuzmanovic, B.; Kuipers, N.J.M.; de Haan, A.B.; Kwant, Gerard
2006-01-01
The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aque
Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions
Kuzmanovic, Boris; Kuipers, Norbert J.M.; Haan, de André B.; Kwant, Gerard
2006-01-01
The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aque
Two-dimensional liquid chromatography
DEFF Research Database (Denmark)
Græsbøll, Rune
Two-dimensional liquid chromatography has received increasing interest due to the rise in demand for analysis of complex chemical mixtures. Separation of complex mixtures is hard to achieve as a simple consequence of the sheer number of analytes, as these samples might contain hundreds or even...... dimensions. As a consequence of the conclusions made within this thesis, the research group has, for the time being, decided against further development of online LC×LC systems, since it was not deemed ideal for the intended application, the analysis of the polar fraction of oil. Trap-and...
Two-dimensional discrete gap breathers in a two-dimensional discrete diatomic Klein-Gordon lattice
Institute of Scientific and Technical Information of China (English)
XU Quan; QIANG Tian
2009-01-01
We study the existence and stability of two-dimensional discrete breathers in a two-dimensional discrete diatomic Klein-Gordon lattice consisting of alternating light and heavy atoms, with nearest-neighbor harmonic coupling.Localized solutions to the corresponding nonlinear differential equations with frequencies inside the gap of the linear wave spectrum, i.e. two-dimensional gap breathers, are investigated numerically. The numerical results of the corresponding algebraic equations demonstrate the possibility of the existence of two-dimensional gap breathers with three types of symmetries, i.e., symmetric, twin-antisymmetric and single-antisymmetric. Their stability depends on the nonlinear on-site potential (soft or hard), the interaction potential (attractive or repulsive)and the center of the two-dimensional gap breather (on a light or a heavy atom).
Two-dimensional quantum repeaters
Wallnöfer, J.; Zwerger, M.; Muschik, C.; Sangouard, N.; Dür, W.
2016-11-01
The endeavor to develop quantum networks gave rise to a rapidly developing field with far-reaching applications such as secure communication and the realization of distributed computing tasks. This ultimately calls for the creation of flexible multiuser structures that allow for quantum communication between arbitrary pairs of parties in the network and facilitate also multiuser applications. To address this challenge, we propose a two-dimensional quantum repeater architecture to establish long-distance entanglement shared between multiple communication partners in the presence of channel noise and imperfect local control operations. The scheme is based on the creation of self-similar multiqubit entanglement structures at growing scale, where variants of entanglement swapping and multiparty entanglement purification are combined to create high-fidelity entangled states. We show how such networks can be implemented using trapped ions in cavities.
Two-dimensional capillary origami
Brubaker, N. D.; Lega, J.
2016-01-01
We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid.
Two-dimensional cubic convolution.
Reichenbach, Stephen E; Geng, Frank
2003-01-01
The paper develops two-dimensional (2D), nonseparable, piecewise cubic convolution (PCC) for image interpolation. Traditionally, PCC has been implemented based on a one-dimensional (1D) derivation with a separable generalization to two dimensions. However, typical scenes and imaging systems are not separable, so the traditional approach is suboptimal. We develop a closed-form derivation for a two-parameter, 2D PCC kernel with support [-2,2] x [-2,2] that is constrained for continuity, smoothness, symmetry, and flat-field response. Our analyses, using several image models, including Markov random fields, demonstrate that the 2D PCC yields small improvements in interpolation fidelity over the traditional, separable approach. The constraints on the derivation can be relaxed to provide greater flexibility and performance.
Bailey, Ryan T.; Morway, Eric D.; Niswonger, Richard G.; Gates, Timothy K.
2013-01-01
A numerical model was developed that is capable of simulating multispecies reactive solute transport in variably saturated porous media. This model consists of a modified version of the reactive transport model RT3D (Reactive Transport in 3 Dimensions) that is linked to the Unsaturated-Zone Flow (UZF1) package and MODFLOW. Referred to as UZF-RT3D, the model is tested against published analytical benchmarks as well as other published contaminant transport models, including HYDRUS-1D, VS2DT, and SUTRA, and the coupled flow and transport modeling system of CATHY and TRAN3D. Comparisons in one-dimensional, two-dimensional, and three-dimensional variably saturated systems are explored. While several test cases are included to verify the correct implementation of variably saturated transport in UZF-RT3D, other cases are included to demonstrate the usefulness of the code in terms of model run-time and handling the reaction kinetics of multiple interacting species in variably saturated subsurface systems. As UZF1 relies on a kinematic-wave approximation for unsaturated flow that neglects the diffusive terms in Richards equation, UZF-RT3D can be used for large-scale aquifer systems for which the UZF1 formulation is reasonable, that is, capillary-pressure gradients can be neglected and soil parameters can be treated as homogeneous. Decreased model run-time and the ability to include site-specific chemical species and chemical reactions make UZF-RT3D an attractive model for efficient simulation of multispecies reactive transport in variably saturated large-scale subsurface systems.
Soltanian, Mohamad Reza; Dai, Zhenxue; Huang, Chaocheng
2014-01-01
Physical and chemical heterogeneities have a large impact on reactive transport in porous media. Examples of heterogeneous attributes affecting reactive mass transport are the hydraulic conductivity (K), and the equilibrium sorption distribution coefficient (Kd). This paper uses the Deng et al. (2013) conceptual model for multimodal reactive mineral facies and a Lagrangian-based stochastic theory in order to analyze the reactive solute dispersion in three-dimensional anisotropic heterogeneous porous media with hierarchical organization of reactive minerals. An example based on real field data is used to illustrate the time evolution trends of reactive solute dispersion. The results show that the correlation between the hydraulic conductivity and the equilibrium sorption distribution coefficient does have a significant effect on reactive solute dispersion. The anisotropy ratio does not have a significant effect on reactive solute dispersion. Furthermore, through a sensitivity analysis we investigate the impact...
Modeling Solute Reactivity in a Phreatic Solution Conduit Penetrating a Karst Aquifer
Field, M.
2014-12-01
A two-dimensional model for solute migration, transformation, and sorption in a phreatic solution conduit penetrating a karst aquifer is presented in which the solute is anthropogenic to the natural system. Transformation of a reacting solute in a solution conduit has generally been accepted as likely occurring but actual physical measurements and mathematical analyses of the suspected process are lacking, primarily because of the logistics of sample collection and the complexities associated with solute transport through solution conduits. The model demonstrates how a reacting solute might be converted to a product solute some of which then diffuses to the solution conduit wall where it may become adsorbed. Model effects vary for laminar flow and turbulent flow in the axial direction. Laminar and turbulent diffusion in the radial direction also exhibits marked differences. In addition to single reaction zones simulations considered multiple adjacent and nonadjacent reaction zones, both with varying reaction rates. Reaction zones were found to enhance subsequent reactions due to some overlap resulting from the hydrodynamic dispersion caused by the axial flow. The simulations showed that varying the reaction rate coefficient strongly affects solute reactions, but that varying deposition coefficients had only minimal impacts. Application of the model to a tracer test that used the tracer dye, Rhodamine WT which readily converts to deaminoalkylated Rhodamine WT after release, illustrates how the model may be used to suggest a possible cause for less than 100% tracer mass recovery. In terms of pollutants in a karst aquifer the model suggests a possible explanation for pollutant transformation in a solution conduit.
Transient transport of reactive and non-reactive solutes in groundwater
Fares, Y. R.; Giacobbe, D.
2004-06-01
A numerical model capable of predicting the transient changes in concentration levels of a solute along a homogeneous aquifer system is presented. The advection-dispersion equation (ADE) is utilised in predicting the concentration levels for cases of continuous and instantaneous release modes. The Crank-Nicholson equation is employed in the presented finite difference model. The numerical calculations are carried out using the implicit Gauss-Seidel method with over- and under-relaxation coefficients depending on the state of convergence. The correction terms resulting from the removal of zero- and first-order truncation errors in the ADE with a reaction term have significantly improved the performance of the numerical scheme. Comparisons between the numerically predicted concentrations with analytical and measured values were carried out for cases of non-reactive (tracer) and reactive (organic) solutes with continuous injection in homogeneous isotropic soils. The overshooting problems experienced in the numerical calculations are minimised by refining the finite grid size. The analysis of results has shown that the model can produce reliable simulations for cases of non-reactive solutes. While for the case of solutes undergoing adsorption, accurate concentrations can be predicted by adjusting the influent pore water velocity through the use of a retardation factor, which is suitable for aquifers with low organic carbon content and undergoing hydrophobic partitioning.
Classifying Two-dimensional Hyporeductive Triple Algebras
Issa, A Nourou
2010-01-01
Two-dimensional real hyporeductive triple algebras (h.t.a.) are investigated. A classification of such algebras is presented. As a consequence, a classification of two-dimensional real Lie triple algebras (i.e. generalized Lie triple systems) and two-dimensional real Bol algebras is given.
Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aqueous solution containing a reactive extractant, like borate salts, borate complexes, a monosalt of dicarboxylic acid,hydroxypropyl-cyclodextrins, and silver nitrate, shows limited potential to be used. Another approach, in which the alcohol is chemically modified prior to the extraction into an easy-extractable form, in this case a monoesterlcarboxylic acid, shows much more potential. An environmentally benign aqueous solution of sodium hydrogen carbonate can provide a distribution ratio of benzyl alcohol up to 200, leaving the solubility of the organic solvent in the aqueous solution unchanged relative to pure water and therefore increasing the selectivity with two orders of magnitude. The modification of aromatic, cyclo-aliphatic, and linear aliphatic alcohols can be performed efficiently in the apolar organic solvent without need for a catalyst. The recovery of the modified alcohol can be performed by back-extraction in combination with a spontaneous hydrolysis.
Perspective: Two-dimensional resonance Raman spectroscopy
Molesky, Brian P.; Guo, Zhenkun; Cheshire, Thomas P.; Moran, Andrew M.
2016-11-01
Two-dimensional resonance Raman (2DRR) spectroscopy has been developed for studies of photochemical reaction mechanisms and structural heterogeneity in complex systems. The 2DRR method can leverage electronic resonance enhancement to selectively probe chromophores embedded in complex environments (e.g., a cofactor in a protein). In addition, correlations between the two dimensions of the 2DRR spectrum reveal information that is not available in traditional Raman techniques. For example, distributions of reactant and product geometries can be correlated in systems that undergo chemical reactions on the femtosecond time scale. Structural heterogeneity in an ensemble may also be reflected in the 2D spectroscopic line shapes of both reactive and non-reactive systems. In this perspective article, these capabilities of 2DRR spectroscopy are discussed in the context of recent applications to the photodissociation reactions of triiodide and myoglobin. We also address key differences between the signal generation mechanisms for 2DRR and off-resonant 2D Raman spectroscopies. Most notably, it has been shown that these two techniques are subject to a tradeoff between sensitivity to anharmonicity and susceptibility to artifacts. Overall, recent experimental developments and applications of the 2DRR method suggest great potential for the future of the technique.
Two-dimensional function photonic crystals
Wu, Xiang-Yao; Liu, Xiao-Jing; Liang, Yu
2016-01-01
In this paper, we have firstly proposed two-dimensional function photonic crystals, which the dielectric constants of medium columns are the functions of space coordinates $\\vec{r}$, it is different from the two-dimensional conventional photonic crystals constituting by the medium columns of dielectric constants are constants. We find the band gaps of two-dimensional function photonic crystals are different from the two-dimensional conventional photonic crystals, and when the functions form of dielectric constants are different, the band gaps structure should be changed, which can be designed into the appropriate band gaps structures by the two-dimensional function photonic crystals.
Radiolysis of Reactive Azo Dyes in Aqueous Solution
Directory of Open Access Journals (Sweden)
Agustin N.M. Bagyo
2004-07-01
Full Text Available The effects of radiation on aerated reactive dye solutions i.e Cibacron Violet, Cibacron Orange and Cibacron Yellow solutions have been studied. Parameters analysis were the change of pH after radiation, the change of absorption, degradation products and effects of pH on the radiolysis. The uv-vis absorption of solutions were observed before and after irradiation. pH variation was done from pHs 3, 5, 7, 9 and 12. Irradiation was done at doses of 0, 2, 4, 6, 8 and 10 kGy with dose rate of 5 kGy/h and was determined by a Fricke dosimeter. HPLC with UV detector was used to analyze the degradation products. Oxalic acid was the main degradation product and small amount of succinic acid was also detected.
Phonon hydrodynamics in two-dimensional materials.
Cepellotti, Andrea; Fugallo, Giorgia; Paulatto, Lorenzo; Lazzeri, Michele; Mauri, Francesco; Marzari, Nicola
2015-03-06
The conduction of heat in two dimensions displays a wealth of fascinating phenomena of key relevance to the scientific understanding and technological applications of graphene and related materials. Here, we use density-functional perturbation theory and an exact, variational solution of the Boltzmann transport equation to study fully from first-principles phonon transport and heat conductivity in graphene, boron nitride, molybdenum disulphide and the functionalized derivatives graphane and fluorographene. In all these materials, and at variance with typical three-dimensional solids, normal processes keep dominating over Umklapp scattering well-above cryogenic conditions, extending to room temperature and more. As a result, novel regimes emerge, with Poiseuille and Ziman hydrodynamics, hitherto typically confined to ultra-low temperatures, characterizing transport at ordinary conditions. Most remarkably, several of these two-dimensional materials admit wave-like heat diffusion, with second sound present at room temperature and above in graphene, boron nitride and graphane.
NUMERICAL SIMULATION OF SOLUTE TRANSPORTSIN TWO DIMENSIONAL VIRTUAL SOIL%二维虚拟土壤中溶质迁移行为的数值模拟研究
Institute of Scientific and Technical Information of China (English)
陶亚奇; 蒋新; 卞永荣; 杨兴伦; 王芳
2009-01-01
Virtual soils, rich in macropore, but different in level, were constructed with the aid of the Voronoi tesselation algorithm on two dimensional lattices and transport behaviors of solute particles therein numerically simulated using random walk models. It was found that the solute diffusion was anomalous and its mean square of displacement was positively correlated with time, being ＜(r→)~2(t)＞∝t~K. Values of K depended on the types of soils and the types of random walk models. With biased random walk models, the values increased with the time, which means the particles diffused faster with the time went on. The first passage time of solute transport satisfied the logarithmic normal distribution. Non-fick effect of the diffusion was obvious with the continuous time random walk theory. And it was found that soils different in por structure would have different corresponding fitting parameters with the random walk models, that is to say, they also affected the transport behaviors of solute particles. The findings of the study are found to be helpful to researchers in understanding and predicting behaviors of water and solutes in macroporous soil, and hence in helping protect the underground water environment.%利用Voronoi图逐级碎裂方法,在二维正方网格上构造出不同等级的虚拟土壤来仿真具有丰富孔隙结构的真实土壤,并借助于随机行走模型,数值模拟了溶质粒子在该虚拟土壤中的迁移行为.结果表明,溶质粒子表现出反常扩散行为.对有偏倚的随机行走模型,其均方位移与时间呈正比关系＜r~2(t)＞∝t~K,即扩散系数D=K-1,长时间的K值更大,溶质粒子扩散更快;首次穿越时间满足正态对数分布,说明溶质粒子迁移是一阶随机过程;由连续时间随机行走理论,发现溶质粒子扩散非费克现象明显.同时发现不同的土壤孔隙结构及随机行走类型所对应的拟合参数不同,即它们也影响溶质粒子的迁移行为.该
Institute of Scientific and Technical Information of China (English)
酒全森
2000-01-01
Some estimates on 2-D Euler equations are given when initial vorticity ω belongs to a Lorentz space L(2,1). Then based on these estimates, it is proved that there exist global weak solutions of two dimensional Euler equations when ω0(2,1)∈L.
Hadamard States and Two-dimensional Gravity
Salehi, H
2001-01-01
We have used a two-dimensional analog of the Hadamard state-condition to study the local constraints on the two-point function of a linear quantum field conformally coupled to a two-dimensional gravitational background. We develop a dynamical model in which the determination of the state of the quantum field is essentially related to the determination of a conformal frame. A particular conformal frame is then introduced in which a two-dimensional gravitational equation is established.
Topological defects in two-dimensional crystals
Chen, Yong; Qi, Wei-Kai
2008-01-01
By using topological current theory, we study the inner topological structure of the topological defects in two-dimensional (2D) crystal. We find that there are two elementary point defects topological current in two-dimensional crystal, one for dislocations and the other for disclinations. The topological quantization and evolution of topological defects in two-dimensional crystals are discussed. Finally, We compare our theory with Brownian-dynamics simulations in 2D Yukawa systems.
Strongly interacting two-dimensional Dirac fermions
Lim, L.K.; Lazarides, A.; Hemmerich, Andreas; de Morais Smith, C.
2009-01-01
We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time reversal and inversion symmetries. We find remarkable phenomena in a temperature
Topology optimization of two-dimensional waveguides
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard; Sigmund, Ole
2003-01-01
In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss.......In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss....
Conservative and reactive solute transport in constructed wetlands
Keefe, S.H.; Barber, L.B.; Runkel, R.L.; Ryan, J.N.; McKnight, Diane M.; Wass, R.D.
2004-01-01
The transport of bromide, a conservative tracer, and rhodamine WT (RWT), a photodegrading tracer, was evaluated in three wastewater-dependent wetlands near Phoenix, Arizona, using a solute transport model with transient storage. Coupled sodium bromide and RWT tracer tests were performed to establish conservative transport and reactive parameters in constructed wetlands with water losses ranging from (1) relatively impermeable (15%), (2) moderately leaky (45%), and (3) significantly leaky (76%). RWT first-order photolysis rates and sorption coefficients were determined from independent field and laboratory experiments. Individual wetland hydraulic profiles influenced the extent of transient storage interaction in stagnant water areas and consequently RWT removal. Solute mixing and transient storage interaction occurred in the impermeable wetland, resulting in 21% RWT mass loss from main channel and storage zone photolysis (10%) and sorption (11%) reactions. Advection and dispersion governed solute transport in the leaky wetland, limiting RWT photolysis removal (1.2%) and favoring main channel sorption (3.6%). The moderately leaky wetland contained islands parallel to flow, producing channel flow and minimizing RWT losses (1.6%).
Non perturbative methods in two dimensional quantum field theory
Abdalla, Elcio; Rothe, Klaus D
1991-01-01
This book is a survey of methods used in the study of two-dimensional models in quantum field theory as well as applications of these theories in physics. It covers the subject since the first model, studied in the fifties, up to modern developments in string theories, and includes exact solutions, non-perturbative methods of study, and nonlinear sigma models.
Two-dimensional static black holes with pointlike sources
Melis, M
2004-01-01
We study the static black hole solutions of generalized two-dimensional dilaton-gravity theories generated by pointlike mass sources, in the hypothesis that the matter is conformally coupled. We also discuss the motion of test particles. Due to conformal coupling, these follow the geodesics of a metric obtained by rescaling the canonical metric with the dilaton.
Dynamics of vortex interactions in two-dimensional flows
DEFF Research Database (Denmark)
Juul Rasmussen, J.; Nielsen, A.H.; Naulin, V.
2002-01-01
a critical value, a(c). Using the Weiss-field, a(c) is estimated for vortex patches. Introducing an effective radius for vortices with distributed vorticity, we find that 3.3 a(c) ...The dynamics and interaction of like-signed vortex structures in two dimensional flows are investigated by means of direct numerical solutions of the two-dimensional Navier-Stokes equations. Two vortices with distributed vorticity merge when their distance relative to their radius, d/R-0l. is below...
Energy Technology Data Exchange (ETDEWEB)
Szybisz, L. (Lab. TANDAR, Dept. de Fisica, Comision Nacional de Energia Atomica, Buenos Aires (Argentina))
1990-08-01
The ground-state wave function for a two-dimensional homogeneous liquid 4He at zero temperature is obtained from a paired-phonon analysis within the HNC/0 approximation. The long-wavelength behavior of the twobody correlation factor, u(q), is studied by following the procedure previously applied to three-dimensional bulk systems. It is shown that a cut-off law for the phonons can be determined by analyzing u(q) at small two-dimensional momenta q. The numerical results strongly support an exponential cut-off similar to that suggested by Chester and Reatto for the bulk liquid. The first-sound velocity c{sub 1} and the cut-off momentum q{sub c} are calculated at several densities in the range 0.028-0.080 A - 2. (orig.).
Energy Technology Data Exchange (ETDEWEB)
George J. Moridis
2001-10-01
In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive solute tracers through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the non-flowing matrix account for (a) diffusion, (b) surface diffusion, (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first-order chemical reactions. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity.
Energy Technology Data Exchange (ETDEWEB)
Moridis, George J.
2001-10-10
In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive solute tracers through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the non-flowing matrix account for (a) diffusion, (b) surface diffusion, (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first-order chemical reactions. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity.
Optical modulators with two-dimensional layered materials
Sun, Zhipei; Wang, Feng
2016-01-01
Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that two-dimensional layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this review, we cover the state-of-the-art of optical modulators based on two-dimensional layered materials including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as two-dimensional heterostructures, plasmonic structures, and silicon/fibre integrated structures. We also take a look at future perspectives and discuss the potential of yet relatively unexplored mechanisms such as magneto-optic and acousto-optic modulation.
Two Dimensional Plasmonic Cavities on Moire Surfaces
Balci, Sinan; Kocabas, Askin; Karabiyik, Mustafa; Kocabas, Coskun; Aydinli, Atilla
2010-03-01
We investigate surface plasmon polariton (SPP) cavitiy modes on two dimensional Moire surfaces in the visible spectrum. Two dimensional hexagonal Moire surface can be recorded on a photoresist layer using Interference lithography (IL). Two sequential exposures at slightly different angles in IL generate one dimensional Moire surfaces. Further sequential exposure for the same sample at slightly different angles after turning the sample 60 degrees around its own axis generates two dimensional hexagonal Moire cavity. Spectroscopic reflection measurements have shown plasmonic band gaps and cavity states at all the azimuthal angles (omnidirectional cavity and band gap formation) investigated. The plasmonic band gap edge and the cavity states energies show six fold symmetry on the two dimensional Moire surface as measured in reflection measurements.
Two-dimensional function photonic crystals
Liu, Xiao-Jing; Liang, Yu; Ma, Ji; Zhang, Si-Qi; Li, Hong; Wu, Xiang-Yao; Wu, Yi-Heng
2017-01-01
In this paper, we have studied two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , that can become true easily by electro-optical effect and optical kerr effect. We calculated the band gap structures of TE and TM waves, and found the TE (TM) wave band gaps of function photonic crystals are wider (narrower) than the conventional photonic crystals. For the two-dimensional function photonic crystals, when the dielectric constant functions change, the band gaps numbers, width and position should be changed, and the band gap structures of two-dimensional function photonic crystals can be adjusted flexibly, the needed band gap structures can be designed by the two-dimensional function photonic crystals, and it can be of help to design optical devices.
Two-Dimensional Planetary Surface Lander
Hemmati, H.; Sengupta, A.; Castillo, J.; McElrath, T.; Roberts, T.; Willis, P.
2014-06-01
A systems engineering study was conducted to leverage a new two-dimensional (2D) lander concept with a low per unit cost to enable scientific study at multiple locations with a single entry system as the delivery vehicle.
Folding two dimensional crystals by swift heavy ion irradiation
Energy Technology Data Exchange (ETDEWEB)
Ochedowski, Oliver; Bukowska, Hanna [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Freire Soler, Victor M. [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Departament de Fisica Aplicada i Optica, Universitat de Barcelona, E08028 Barcelona (Spain); Brökers, Lara [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Ban-d' Etat, Brigitte; Lebius, Henning [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France); Schleberger, Marika, E-mail: marika.schleberger@uni-due.de [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany)
2014-12-01
Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS{sub 2} and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS{sub 2} does not.
NONLINEAR GALERKIN METHODS FOR SOLVING TWO DIMENSIONAL NEWTON-BOUSSINESQ EQUATIONS
Institute of Scientific and Technical Information of China (English)
GUOBOLING
1995-01-01
The nonlinear Galerkin methods for solving two-dimensional Newton-Boussinesq equations are proposed. The existence and uniqueness of global generalized solution of these equations,and the convergence of approximate solutions are also obtained.
Large-scale modeling of reactive solute transport in fracture zones of granitic bedrocks
Molinero, Jorge; Samper, Javier
2006-01-01
Final disposal of high-level radioactive waste in deep repositories located in fractured granite formations is being considered by several countries. The assessment of the safety of such repositories requires using numerical models of groundwater flow, solute transport and chemical processes. These models are being developed from data and knowledge gained from in situ experiments such as the Redox Zone Experiment carried out at the underground laboratory of Äspö in Sweden. This experiment aimed at evaluating the effects of the construction of the access tunnel on the hydrogeological and hydrochemical conditions of a fracture zone intersected by the tunnel. Most chemical species showed dilution trends except for bicarbonate and sulphate which unexpectedly increased with time. Molinero and Samper [Molinero, J. and Samper, J. Groundwater flow and solute transport in fracture zones: an improved model for a large-scale field experiment at Äspö (Sweden). J. Hydraul. Res., 42, Extra Issue, 157-172] presented a two-dimensional water flow and solute transport finite element model which reproduced measured drawdowns and dilution curves of conservative species. Here we extend their model by using a reactive transport which accounts for aqueous complexation, acid-base, redox processes, dissolution-precipitation of calcite, quartz, hematite and pyrite, and cation exchange between Na + and Ca 2+. The model provides field-scale estimates of cation exchange capacity of the fracture zone and redox potential of groundwater recharge. It serves also to identify the mineral phases controlling the solubility of iron. In addition, the model is useful to test the relevance of several geochemical processes. Model results rule out calcite dissolution as the process causing the increase in bicarbonate concentration and reject the following possible sources of sulphate: (1) pyrite dissolution, (2) leaching of alkaline sulphate-rich waters from a nearby rock landfill and (3) dissolution of
Interpolation by two-dimensional cubic convolution
Shi, Jiazheng; Reichenbach, Stephen E.
2003-08-01
This paper presents results of image interpolation with an improved method for two-dimensional cubic convolution. Convolution with a piecewise cubic is one of the most popular methods for image reconstruction, but the traditional approach uses a separable two-dimensional convolution kernel that is based on a one-dimensional derivation. The traditional, separable method is sub-optimal for the usual case of non-separable images. The improved method in this paper implements the most general non-separable, two-dimensional, piecewise-cubic interpolator with constraints for symmetry, continuity, and smoothness. The improved method of two-dimensional cubic convolution has three parameters that can be tuned to yield maximal fidelity for specific scene ensembles characterized by autocorrelation or power-spectrum. This paper illustrates examples for several scene models (a circular disk of parametric size, a square pulse with parametric rotation, and a Markov random field with parametric spatial detail) and actual images -- presenting the optimal parameters and the resulting fidelity for each model. In these examples, improved two-dimensional cubic convolution is superior to several other popular small-kernel interpolation methods.
Two-dimensional localized structures in harmonically forced oscillatory systems
Ma, Y.-P.; Knobloch, E.
2016-12-01
Two-dimensional spatially localized structures in the complex Ginzburg-Landau equation with 1:1 resonance are studied near the simultaneous presence of a steady front between two spatially homogeneous equilibria and a supercritical Turing bifurcation on one of them. The bifurcation structures of steady circular fronts and localized target patterns are computed in the Turing-stable and Turing-unstable regimes. In particular, localized target patterns grow along the solution branch via ring insertion at the core in a process reminiscent of defect-mediated snaking in one spatial dimension. Stability of axisymmetric solutions on these branches with respect to axisymmetric and nonaxisymmetric perturbations is determined, and parameter regimes with stable axisymmetric oscillons are identified. Direct numerical simulations reveal novel depinning dynamics of localized target patterns in the radial direction, and of circular and planar localized hexagonal patterns in the fully two-dimensional system.
TWO-DIMENSIONAL TOPOLOGY OF COSMOLOGICAL REIONIZATION
Energy Technology Data Exchange (ETDEWEB)
Wang, Yougang; Xu, Yidong; Chen, Xuelei [Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 China (China); Park, Changbom [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of); Kim, Juhan, E-mail: wangyg@bao.ac.cn, E-mail: cbp@kias.re.kr [Center for Advanced Computation, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of)
2015-11-20
We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two-dimensional genus curve for the early, middle, and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometre Array.
Two dimensional topology of cosmological reionization
Wang, Yougang; Xu, Yidong; Chen, Xuelei; Kim, Juhan
2015-01-01
We study the two-dimensional topology of the 21-cm differential brightness temperature for two hydrodynamic radiative transfer simulations and two semi-numerical models. In each model, we calculate the two dimensional genus curve for the early, middle and late epochs of reionization. It is found that the genus curve depends strongly on the ionized fraction of hydrogen in each model. The genus curves are significantly different for different reionization scenarios even when the ionized faction is the same. We find that the two-dimensional topology analysis method is a useful tool to constrain the reionization models. Our method can be applied to the future observations such as those of the Square Kilometer Array.
Conductivity of a two-dimensional guiding center plasma.
Montgomery, D.; Tappert, F.
1972-01-01
The Kubo method is used to calculate the electrical conductivity of a two-dimensional, strongly magnetized plasma. The particles interact through (logarithmic) electrostatic potentials and move with their guiding center drift velocities (Taylor-McNamara model). The thermal equilibrium dc conductivity can be evaluated analytically, but the ac conductivity involves numerical solution of a differential equation. Both conductivities fall off as the inverse first power of the magnetic field strength.
Lyapunov Computational Method for Two-Dimensional Boussinesq Equation
Mabrouk, Anouar Ben
2010-01-01
A numerical method is developed leading to Lyapunov operators to approximate the solution of two-dimensional Boussinesq equation. It consists of an order reduction method and a finite difference discretization. It is proved to be uniquely solvable and analyzed for local truncation error for consistency. The stability is checked by using Lyapunov criterion and the convergence is studied. Some numerical implementations are provided at the end of the paper to validate the theoretical results.
Chronology Protection in Two-Dimensional Dilaton Gravity
Mishima, T; Mishima, Takashi; Nakamichi, Akika
1994-01-01
The global structure of 1 + 1 dimensional compact Universe is studied in two-dimensional model of dilaton gravity. First we give a classical solution corresponding to the spacetime in which a closed time-like curve appears, and show the instability of this spacetime due to the existence of matters. We also observe quantum version of such a spacetime having closed timelike curves never reappear unless the parameters are fine-tuned.
Exact analytic flux distributions for two-dimensional solar concentrators.
Fraidenraich, Naum; Henrique de Oliveira Pedrosa Filho, Manoel; Vilela, Olga C; Gordon, Jeffrey M
2013-07-01
A new approach for representing and evaluating the flux density distribution on the absorbers of two-dimensional imaging solar concentrators is presented. The formalism accommodates any realistic solar radiance and concentrator optical error distribution. The solutions obviate the need for raytracing, and are physically transparent. Examples illustrating the method's versatility are presented for parabolic trough mirrors with both planar and tubular absorbers, Fresnel reflectors with tubular absorbers, and V-trough mirrors with planar absorbers.
Two-dimensional x-ray diffraction
He, Bob B
2009-01-01
Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea
Matching Two-dimensional Gel Electrophoresis' Spots
DEFF Research Database (Denmark)
Dos Anjos, António; AL-Tam, Faroq; Shahbazkia, Hamid Reza
2012-01-01
This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This ar......This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches...
Mobility anisotropy of two-dimensional semiconductors
Lang, Haifeng; Zhang, Shuqing; Liu, Zhirong
2016-12-01
The carrier mobility of anisotropic two-dimensional semiconductors under longitudinal acoustic phonon scattering was theoretically studied using deformation potential theory. Based on the Boltzmann equation with the relaxation time approximation, an analytic formula of intrinsic anisotropic mobility was derived, showing that the influence of effective mass on mobility anisotropy is larger than those of deformation potential constant or elastic modulus. Parameters were collected for various anisotropic two-dimensional materials (black phosphorus, Hittorf's phosphorus, BC2N , MXene, TiS3, and GeCH3) to calculate their mobility anisotropy. It was revealed that the anisotropic ratio is overestimated by the previously described method.
Towards two-dimensional search engines
Ermann, Leonardo; Chepelianskii, Alexei D.; Shepelyansky, Dima L.
2011-01-01
We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way the ranking of nodes becomes two-dimensional that paves the way for development of two-dimensional search engines of new type. Statistical properties of inf...
Piezoelectricity in Two-Dimensional Materials
Wu, Tao
2015-02-25
Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards embedding low-dimensional materials into future disruptive technologies. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.
Kronecker Product of Two-dimensional Arrays
Institute of Scientific and Technical Information of China (English)
Lei Hu
2006-01-01
Kronecker sequences constructed from short sequences are good sequences for spread spectrum communication systems. In this paper we study a similar problem for two-dimensional arrays, and we determine the linear complexity of the Kronecker product of two arrays. Our result shows that similar good property on linear complexity holds for Kronecker product of arrays.
A novel two dimensional particle velocity sensor
Pjetri, Olti; Wiegerink, Remco J.; Lammerink, Theo S.; Krijnen, Gijs J.
2013-01-01
In this paper we present a two wire, two-dimensional particle velocity sensor. The miniature sensor of size 1.0x2.5x0.525 mm, consisting of only two crossed wires, shows excellent directional sensitivity in both directions, thus requiring no directivity calibration, and is relatively easy to fabrica
Two-dimensional microstrip detector for neutrons
Energy Technology Data Exchange (ETDEWEB)
Oed, A. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1997-04-01
Because of their robust design, gas microstrip detectors, which were developed at ILL, can be assembled relatively quickly, provided the prefabricated components are available. At the beginning of 1996, orders were received for the construction of three two-dimensional neutron detectors. These detectors have been completed. The detectors are outlined below. (author). 2 refs.
Two-dimensional magma-repository interactions
Bokhove, O.
2001-01-01
Two-dimensional simulations of magma-repository interactions reveal that the three phases --a shock tube, shock reflection and amplification, and shock attenuation and decay phase-- in a one-dimensional flow tube model have a precursor. This newly identified phase ``zero'' consists of the impact of
Two-dimensional subwavelength plasmonic lattice solitons
Ye, F; Hu, B; Panoiu, N C
2010-01-01
We present a theoretical study of plasmonic lattice solitons (PLSs) formed in two-dimensional (2D) arrays of metallic nanowires embedded into a nonlinear medium with Kerr nonlinearity. We analyze two classes of 2D PLSs families, namely, fundamental and vortical PLSs in both focusing and defocusing media. Their existence, stability, and subwavelength spatial confinement are studied in detai
A two-dimensional Dirac fermion microscope
DEFF Research Database (Denmark)
Bøggild, Peter; Caridad, Jose; Stampfer, Christoph
2017-01-01
in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2...
Directory of Open Access Journals (Sweden)
A. Aghili
2011-12-01
Full Text Available In this work,we present new theorems on two-dimensional Laplace transformation. We also develop some applications based on these results. The two-dimensional Laplace transformation is useful in the solution of non-homogeneous partial differential equations. In the last section a boundary value problem is solved by using the double Laplace-Carson transform.
Ultrafast two dimensional infrared chemical exchange spectroscopy
Fayer, Michael
2011-03-01
The method of ultrafast two dimensional infrared (2D IR) vibrational echo spectroscopy is described. Three ultrashort IR pulses tuned to the frequencies of the vibrational transitions of interest are directed into the sample. The interaction of these pulses with the molecular vibrational oscillators produces a polarization that gives rise to a fourth pulse, the vibrational echo. The vibrational echo pulse is combined with another pulse, the local oscillator, for heterodyne detection of the signal. For fixed time between the second and third pulses, the waiting time, the first pulse is scanned. Two Fourier transforms of the data yield a 2D IR spectrum. The waiting time is increased, and another spectrum is obtained. The change in the 2D IR spectra with increased waiting time provides information on the time evolution of the structure of the molecular system under observation. In a 2D IR chemical exchange experiment, two species A and B, are undergoing chemical exchange. A's are turning into B's, and B's are turning into A's, but the overall concentrations of the species are not changing. The kinetics of the chemical exchange on the ground electronic state under thermal equilibrium conditions can be obtained 2D IR spectroscopy. A vibration that has a different frequency for the two species is monitored. At very short time, there will be two peaks on the diagonal of the 2D IR spectrum, one for A and one for B. As the waiting time is increased, chemical exchange causes off-diagonal peaks to grow in. The time dependence of the growth of these off-diagonal peaks gives the chemical exchange rate. The method is applied to organic solute-solvent complex formation, orientational isomerization about a carbon-carbon single bond, migration of a hydrogen bond from one position on a molecule to another, protein structural substate interconversion, and water hydrogen bond switching between ions and water molecules. This work was supported by the Air Force Office of Scientific
Two dimensional soft material: new faces of graphene oxide.
Kim, Jaemyung; Cote, Laura J; Huang, Jiaxing
2012-08-21
Graphite oxide sheets, now called graphene oxide (GO), can be made from chemical exfoliation of graphite by reactions that have been known for 150 years. Because GO is a promising solution-processable precursor for the bulk production of graphene, interest in this old material has resurged. The reactions to produce GO add oxygenated functional groups to the graphene sheets on their basal plane and edges, and this derivatization breaks the π-conjugated network, resulting in electrically insulating but highly water-dispersible sheets. Apart from making graphene, GO itself has many intriguing properties. Like graphene, GO is a two-dimensional (2D) sheet with feature sizes at two abruptly different length scales. The apparent thickness of the functionalized carbon sheet is approximately 1 nm, but the lateral dimensions can range from a few nanometers to hundreds of micrometers. Therefore, researchers can think of GO as either a single molecule or a particle, depending on which length scale is of greater interest. At the same time, GO can be viewed as an unconventional soft material, such as a 2D polymer, highly anisotropic colloid, membrane, liquid crystal, or amphiphile. In this Account, we highlight the soft material characteristics of GO. GO consists of nanographitic patches surrounded by largely disordered, oxygenated domains. Such structural characteristics effectively make GO a 2D amphiphile with a hydrophilic periphery and largely hydrophobic center. This insight has led to better understanding of the solution properties of GO for making thin films and new applications of GO as a surfactant. Changes in pH and sheet size can tune the amphiphilicity of GO, leading to intriguing interfacial activities. In addition, new all-carbon composites made of only graphitic nanostructures using GO as a dispersing agent have potential applications in photovoltaics and energy storage. On the other hand, GO can function as a 2D random diblock copolymer, one block graphitic and
Two-dimensional capillary electrophoresis using tangentially connected capillaries.
Sahlin, Eskil
2007-06-22
A novel type of fused silica capillary system is described where channels with circular cross-sections are tangentially in contact with each other and connected through a small opening at the contact area. Since the channels are not crossing each other in the same plane, the capillaries can easily be filled with different solutions, i.e. different solutions will be in contact with each other at the contact point. The system has been used to perform different types of two-dimensional separations and the complete system is fully automated where a high voltage switch is used to control the location of the high voltage in the system. Using two model compounds it is demonstrated that a type of two-dimensional separation can be performed using capillary zone electrophoresis at two different pH values. It is also shown that a compound with acid/base properties can be concentrated using a dynamic pH junction mechanism when transferred from the first separation to the second separation. In addition, the system has been used to perform a comprehensive two-dimensional capillary electrophoresis separation of tryptic digest of bovine serum albumin using capillary zone electrophoresis followed by micellar electrokinetic chromatography.
Electronics based on two-dimensional materials.
Fiori, Gianluca; Bonaccorso, Francesco; Iannaccone, Giuseppe; Palacios, Tomás; Neumaier, Daniel; Seabaugh, Alan; Banerjee, Sanjay K; Colombo, Luigi
2014-10-01
The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.
Two-dimensional ranking of Wikipedia articles
Zhirov, A. O.; Zhirov, O. V.; Shepelyansky, D. L.
2010-10-01
The Library of Babel, described by Jorge Luis Borges, stores an enormous amount of information. The Library exists ab aeterno. Wikipedia, a free online encyclopaedia, becomes a modern analogue of such a Library. Information retrieval and ranking of Wikipedia articles become the challenge of modern society. While PageRank highlights very well known nodes with many ingoing links, CheiRank highlights very communicative nodes with many outgoing links. In this way the ranking becomes two-dimensional. Using CheiRank and PageRank we analyze the properties of two-dimensional ranking of all Wikipedia English articles and show that it gives their reliable classification with rich and nontrivial features. Detailed studies are done for countries, universities, personalities, physicists, chess players, Dow-Jones companies and other categories.
Two-Dimensional NMR Lineshape Analysis
Waudby, Christopher A.; Ramos, Andres; Cabrita, Lisa D.; Christodoulou, John
2016-04-01
NMR titration experiments are a rich source of structural, mechanistic, thermodynamic and kinetic information on biomolecular interactions, which can be extracted through the quantitative analysis of resonance lineshapes. However, applications of such analyses are frequently limited by peak overlap inherent to complex biomolecular systems. Moreover, systematic errors may arise due to the analysis of two-dimensional data using theoretical frameworks developed for one-dimensional experiments. Here we introduce a more accurate and convenient method for the analysis of such data, based on the direct quantum mechanical simulation and fitting of entire two-dimensional experiments, which we implement in a new software tool, TITAN (TITration ANalysis). We expect the approach, which we demonstrate for a variety of protein-protein and protein-ligand interactions, to be particularly useful in providing information on multi-step or multi-component interactions.
Towards two-dimensional search engines
Ermann, Leonardo; Shepelyansky, Dima L
2011-01-01
We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way the ranking of nodes becomes two-dimensional that paves the way for development of two-dimensional search engines of new type. Information flow properties on PageRank-CheiRank plane are analyzed for networks of British, French and Italian Universities, Wikipedia, Linux Kernel, gene regulation and other networks. Methods of spam links control are also analyzed.
Toward two-dimensional search engines
Ermann, L.; Chepelianskii, A. D.; Shepelyansky, D. L.
2012-07-01
We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way, the ranking of nodes becomes two dimensional which paves the way for the development of two-dimensional search engines of a new type. Statistical properties of information flow on the PageRank-CheiRank plane are analyzed for networks of British, French and Italian universities, Wikipedia, Linux Kernel, gene regulation and other networks. A special emphasis is done for British universities networks using the large database publicly available in the UK. Methods of spam links control are also analyzed.
A two-dimensional Dirac fermion microscope
Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads
2017-06-01
The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.
A two-dimensional Dirac fermion microscope.
Bøggild, Peter; Caridad, José M; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads
2017-06-09
The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.
Two-Dimensional Scheduling: A Review
Directory of Open Access Journals (Sweden)
Zhuolei Xiao
2013-07-01
Full Text Available In this study, we present a literature review, classification schemes and analysis of methodology for scheduling problems on Batch Processing machine (BP with both processing time and job size constraints which is also regarded as Two-Dimensional (TD scheduling. Special attention is given to scheduling problems with non-identical job sizes and processing times, with details of the basic algorithms and other significant results.
Two dimensional fermions in four dimensional YM
Narayanan, R
2009-01-01
Dirac fermions in the fundamental representation of SU(N) live on a two dimensional torus flatly embedded in $R^4$. They interact with a four dimensional SU(N) Yang Mills vector potential preserving a global chiral symmetry at finite $N$. As the size of the torus in units of $\\frac{1}{\\Lambda_{SU(N)}}$ is varied from small to large, the chiral symmetry gets spontaneously broken in the infinite $N$ limit.
Two-dimensional Kagome photonic bandgap waveguide
DEFF Research Database (Denmark)
Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou;
2000-01-01
The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....
String breaking in two-dimensional QCD
Hornbostel, K J
1999-01-01
I present results of a numerical calculation of the effects of light quark-antiquark pairs on the linear heavy-quark potential in light-cone quantized two-dimensional QCD. I extract the potential from the Q-Qbar component of the ground-state wavefunction, and observe string breaking at the heavy-light meson pair threshold. I briefly comment on the states responsible for the breaking.
Two-dimensional supramolecular electron spin arrays.
Wäckerlin, Christian; Nowakowski, Jan; Liu, Shi-Xia; Jaggi, Michael; Siewert, Dorota; Girovsky, Jan; Shchyrba, Aneliia; Hählen, Tatjana; Kleibert, Armin; Oppeneer, Peter M; Nolting, Frithjof; Decurtins, Silvio; Jung, Thomas A; Ballav, Nirmalya
2013-05-07
A bottom-up approach is introduced to fabricate two-dimensional self-assembled layers of molecular spin-systems containing Mn and Fe ions arranged in a chessboard lattice. We demonstrate that the Mn and Fe spin states can be reversibly operated by their selective response to coordination/decoordination of volatile ligands like ammonia (NH3). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Two dimensional echocardiographic detection of intraatrial masses.
DePace, N L; Soulen, R L; Kotler, M N; Mintz, G S
1981-11-01
With two dimensional echocardiography, a left atrial mass was detected in 19 patients. Of these, 10 patients with rheumatic mitral stenosis had a left atrial thrombus. The distinctive two dimensional echocardiographic features of left atrial thrombus included a mass of irregular nonmobile laminated echos within an enlarged atrial cavity, usually with a broad base of attachment to the posterior left atrial wall. Seven patients had a left atrial myxoma. Usually, the myxoma appeared as a mottled ovoid, sharply demarcated mobile mass attached to the interatrial septum. One patient had a right atrial angiosarcoma that appeared as a nonmobile mass extending from the inferior vena caval-right atrial junction into the right atrial cavity. One patient had a left atrial leiomyosarcoma producing a highly mobile mass attached to the lateral wall of the left atrium. M mode echocardiography detected six of the seven myxomas, one thrombus and neither of the other tumors. Thus, two dimensional echocardiography appears to be the technique of choice in the detection, localization and differentiation of intraatrial masses.
Aumelas, A; Chiche, L; Kubo, S; Chino, N; Tamaoki, H; Kobayashi, Y
1995-04-11
Addition of the Lys(-2)-Arg(-1) dipeptide, present in the precursor protein, to the N-terminus of endothelin-1 (ET-1), to form a 23-residue peptide (KR-ET-1) has been shown to greatly improve formation of native disulfide bridges and to dramatically decrease biological activity. Conformational analysis was carried out on this peptide. During protonation of the carboxyl groups, CD spectra showed a decrease in the helical contribution, and NMR spectra displayed strong chemical shift modifications, suggesting the importance of electrostatic interactions in the KR-ET-1 conformation. CD spectra and two-dimensional NMR experiments were performed to investigate the KR-ET-1 three-dimensional structure in water in the carboxylic acid and carboxylate states. Distance and angle constraints were used as input for distance geometry calculations. The KR-ET-1 carboxylic acid conformation was found to be very similar to ET-1, with a helix spanning residues 9-15 and an unconstrained C-terminal part. In contrast, in the carboxylate state, large changes in Arg(-1) and Phe14 chemical shifts and long-range NOEs were consistent with a conformation characterized by a helix extension to Leu17 and a stabilized C-terminal section folded back toward the N-terminus. In addition, thanks to NOEs with Cys11 and Phe14, the Arg(-1) side chain appeared well-defined. Simulated annealing and molecular dynamics calculations, supported an Arg(-1)-Glu10 salt bridge and an electrostatic network involving the charged groups of Trp21, Asp18, and Lys(-2). Moreover, stabilization of the KR-ET-1 C-terminal part is probably reinforced by hydrophobic interactions involving the Val12, Tyr13, Phe14, Leu17, Ile19, Ile20, and Trp21 side chains. In vitro, native disulfide bond formation improvement observed for KR-ET-1 could be ascribed to electrostatic interactions and more specifically to the Arg(-1)-Glu10 salt bridge. In vivo, similar interactions could play an important role in the native folding of the ET-1
Removal of low molecular organic acids from aqueous solutions with reactive extraction
National Research Council Canada - National Science Library
Dominika Szternel; Magdalena Regel-Rosocka; Maciej Wiśniewski
2013-01-01
...) from aqueous solutions with reactive extraction. The results specifically show that the extraction efficiency of acids depends on the type of extractant, diluents of the organic phase and the initial pH of the aqueous phase...
A novel schedule for solving the two-dimensional diffusion problem in fractal heat transfer
Directory of Open Access Journals (Sweden)
Xu Shu
2015-01-01
Full Text Available In this work, the local fractional variational iteration method is employed to obtain approximate analytical solution of the two-dimensional diffusion equation in fractal heat transfer with help of local fractional derivative and integral operators.
A two-dimensional analytical model of petroleum vapor intrusion
Yao, Yijun; Verginelli, Iason; Suuberg, Eric M.
2016-02-01
In this study we present an analytical solution of a two-dimensional petroleum vapor intrusion model, which incorporates a steady-state diffusion-dominated vapor transport in a homogeneous soil and piecewise first-order aerobic biodegradation limited by oxygen availability. This new model can help practitioners to easily generate two-dimensional soil gas concentration profiles for both hydrocarbons and oxygen and estimate hydrocarbon indoor air concentrations as a function of site-specific conditions such as source strength and depth, reaction rate constant, soil characteristics and building features. The soil gas concentration profiles generated by this new model are shown in good agreement with three-dimensional numerical simulations and two-dimensional measured soil gas data from a field study. This implies that for cases involving diffusion dominated soil gas transport, steady state conditions and homogenous source and soil, this analytical model can be used as a fast and easy-to-use risk screening tool by replicating the results of 3-D numerical simulations but with much less computational effort.
Directory of Open Access Journals (Sweden)
D. A. Fetisov
2015-01-01
Full Text Available The controllability conditions are well known if we speak about linear stationary systems: a linear stationary system is controllable if and only if the dimension of the state vector is equal to the rank of the controllability matrix. The concept of the controllability matrix is extended to affine systems, but relations between affine systems controllability and properties of this matrix are more complicated. Various controllability conditions are set for affine systems, but they deal as usual either with systems of some special form or with controllability in some small neighborhood of the concerned point. An affine system is known to be controllable if the system is equivalent to a system of a canonical form, which is defined and regular in the whole space of states. In this case, the system is said to be feedback linearizable in the space of states. However there are examples, which illustrate that a system can be controllable even if it is not feedback linearizable in any open subset in the space of states. In this article we deal with such systems.Affine systems with two-dimensional control are considered. The system in question is assumed to be equivalent to a system of a quasicanonical form with two-dimensional zero dynamics which is defined and regular in the whole space of states. Therefore the controllability of the original system is equivalent to the controllability of the received system of a quasicanonical form. In this article the sufficient condition for an available solution of the terminal problem is proven for systems of a quasicanonical form with two-dimensional control and two-dimensional zero dynamics. The condition is valid in the case of an arbitrary time interval and arbitrary initial and finite states of the system. Therefore the controllability condition is set for systems of a quasicanonical form with two-dimensional control and two-dimensional zero dynamics. An example is given which illustrates how the proved
Energy Technology Data Exchange (ETDEWEB)
Chatterjee, Kausik, E-mail: kausik.chatterjee@aggiemail.usu.edu [Strategic and Military Space Division, Space Dynamics Laboratory, North Logan, UT 84341 (United States); Center for Atmospheric and Space Sciences, Utah State University, Logan, UT 84322 (United States); Roadcap, John R., E-mail: john.roadcap@us.af.mil [Air Force Research Laboratory, Kirtland AFB, NM 87117 (United States); Singh, Surendra, E-mail: surendra-singh@utulsa.edu [Department of Electrical Engineering, The University of Tulsa, Tulsa, OK 74104 (United States)
2014-11-01
The objective of this paper is the exposition of a recently-developed, novel Green's function Monte Carlo (GFMC) algorithm for the solution of nonlinear partial differential equations and its application to the modeling of the plasma sheath region around a cylindrical conducting object, carrying a potential and moving at low speeds through an otherwise neutral medium. The plasma sheath is modeled in equilibrium through the GFMC solution of the nonlinear Poisson–Boltzmann (NPB) equation. The traditional Monte Carlo based approaches for the solution of nonlinear equations are iterative in nature, involving branching stochastic processes which are used to calculate linear functionals of the solution of nonlinear integral equations. Over the last several years, one of the authors of this paper, K. Chatterjee has been developing a philosophically-different approach, where the linearization of the equation of interest is not required and hence there is no need for iteration and the simulation of branching processes. Instead, an approximate expression for the Green's function is obtained using perturbation theory, which is used to formulate the random walk equations within the problem sub-domains where the random walker makes its walks. However, as a trade-off, the dimensions of these sub-domains have to be restricted by the limitations imposed by perturbation theory. The greatest advantage of this approach is the ease and simplicity of parallelization stemming from the lack of the need for iteration, as a result of which the parallelization procedure is identical to the parallelization procedure for the GFMC solution of a linear problem. The application area of interest is in the modeling of the communication breakdown problem during a space vehicle's re-entry into the atmosphere. However, additional application areas are being explored in the modeling of electromagnetic propagation through the atmosphere/ionosphere in UHF/GPS applications.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The solution-phase synthesis by chemical transformation from reactive templates has proved to be very effective in morphology-controlled synthesis of inorganic nanostructures. This review paper summarizes the recent progress in solution-phase synthesis of one-dimensional and hollow inorganic nanostructures via reactive templates, focusing on the approaches developed in our lab. The formation mechanisms based on reactive templates are discussed in depth to show the general concepts for the preparation processes. An outlook on the future development in this area is also presented.
Reactive Oxygen: a new solution to antimicrobial resistance.
2016-06-23
In April of this year tissue viability nurses, professors, surgeons, and microbiologists met at the University of Birmingham to discuss a real solution to the developing antibiotic resistance catastrophe.
ANALYSIS OF THE REACTIVITY OF RADPRO SOLUTION WITH COTTON RAGS
Energy Technology Data Exchange (ETDEWEB)
MARUSICH RM
2009-08-11
Rags containing RadPro{reg_sign} solution will be generated during the decontamination of the Plutonium Finishing Plant (PFP). Under normal conditions, the rags will be neutralized with sodium carbonate prior to placing in the drums. The concern with RadPro solutions and cotton rags is that some of the RadPro solutions contain nitric acid. Under the right conditions, nitric acid and cotton rags exothermically react. The concern is, will RadPro solutions react with cotton rags exothermically? The potential for a runaway reaction for any of the RadPro solutions used was studied in Section 5.2 of PNNL-15410, Thermal Stability Studies of Candidate Decontamination Agents for Hanford's Plutonium Finishing Plant Plutonium-Contaminated Gloveboxes. This report shows the thermal behavior of cotton rags having been saturated in one of the various neutralized and non-neutralized RadPro solutions. The thermal analysis was performed using thermogravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and Accelerating Rate Calorimetry (ARC).
Weakly disordered two-dimensional Frenkel excitons
Boukahil, A.; Zettili, Nouredine
2004-03-01
We report the results of studies of the optical properties of weakly disordered two- dimensional Frenkel excitons in the Coherent Potential Approximation (CPA). An approximate complex Green's function for a square lattice with nearest neighbor interactions is used in the self-consistent equation to determine the coherent potential. It is shown that the Density of States is very much affected by the logarithmic singularities in the Green's function. Our CPA results are in excellent agreement with previous investigations by Schreiber and Toyozawa using the Monte Carlo simulation.
Two-dimensional photonic crystal surfactant detection.
Zhang, Jian-Tao; Smith, Natasha; Asher, Sanford A
2012-08-07
We developed a novel two-dimensional (2-D) crystalline colloidal array photonic crystal sensing material for the visual detection of amphiphilic molecules in water. A close-packed polystyrene 2-D array monolayer was embedded in a poly(N-isopropylacrylamide) (PNIPAAm)-based hydrogel film. These 2-D photonic crystals placed on a mirror show intense diffraction that enables them to be used for visual determination of analytes. Binding of surfactant molecules attaches ions to the sensor that swells the PNIPAAm-based hydrogel. The resulting increase in particle spacing red shifts the 2-D diffracted light. Incorporation of more hydrophobic monomers increases the sensitivity to surfactants.
Theory of two-dimensional transformations
Kanayama, Yutaka J.; Krahn, Gary W.
1998-01-01
The article of record may be found at http://dx.doi.org/10.1109/70.720359 Robotics and Automation, IEEE Transactions on This paper proposes a new "heterogeneous" two-dimensional (2D) transformation group ___ to solve motion analysis/planning problems in robotics. In this theory, we use a 3×1 matrix to represent a transformation as opposed to a 3×3 matrix in the homogeneous formulation. First, this theory is as capable as the homogeneous theory, Because of the minimal size, its implement...
Two-dimensional ranking of Wikipedia articles
Zhirov, A O; Shepelyansky, D L
2010-01-01
The Library of Babel, described by Jorge Luis Borges, stores an enormous amount of information. The Library exists {\\it ab aeterno}. Wikipedia, a free online encyclopaedia, becomes a modern analogue of such a Library. Information retrieval and ranking of Wikipedia articles become the challenge of modern society. We analyze the properties of two-dimensional ranking of all Wikipedia English articles and show that it gives their reliable classification with rich and nontrivial features. Detailed studies are done for countries, universities, personalities, physicists, chess players, Dow-Jones companies and other categories.
Mobility anisotropy of two-dimensional semiconductors
Lang, Haifeng; Liu, Zhirong
2016-01-01
The carrier mobility of anisotropic two-dimensional (2D) semiconductors under longitudinal acoustic (LA) phonon scattering was theoretically studied with the deformation potential theory. Based on Boltzmann equation with relaxation time approximation, an analytic formula of intrinsic anisotropic mobility was deduced, which shows that the influence of effective mass to the mobility anisotropy is larger than that of deformation potential constant and elastic modulus. Parameters were collected for various anisotropic 2D materials (black phosphorus, Hittorf's phosphorus, BC$_2$N, MXene, TiS$_3$, GeCH$_3$) to calculate their mobility anisotropy. It was revealed that the anisotropic ratio was overestimated in the past.
Sums of two-dimensional spectral triples
DEFF Research Database (Denmark)
Christensen, Erik; Ivan, Cristina
2007-01-01
construct a sum of two dimensional modules which reflects some aspects of the topological dimensions of the compact metric space, but this will only give the metric back approximately. At the end we make an explicit computation of the last module for the unit interval in. The metric is recovered exactly......, the Dixmier trace induces a multiple of the Lebesgue integral but the growth of the number of eigenvalues is different from the one found for the standard differential operator on the unit interval....
Binding energy of two-dimensional biexcitons
DEFF Research Database (Denmark)
Singh, Jai; Birkedal, Dan; Vadim, Lyssenko;
1996-01-01
Using a model structure for a two-dimensional (2D) biexciton confined in a quantum well, it is shown that the form of the Hamiltonian of the 2D biexciton reduces into that of an exciton. The binding energies and Bohr radii of a 2D biexciton in its various internal energy states are derived...... analytically using the fractional dimension approach. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be 0.228, which agrees very well with the recent experimental value. The results of our approach are compared with those of earlier theories....
Dynamics of film. [two dimensional continua theory
Zak, M.
1979-01-01
The general theory of films as two-dimensional continua are elaborated upon. As physical realizations of such a model this paper examines: inextensible films, elastic films, and nets. The suggested dynamic equations have enabled us to find out the characteristic speeds of wave propagation of the invariants of external and internal geometry and formulate the criteria of instability of their shape. Also included herein is a detailed account of the equation describing the film motions beyond the limits of the shape stability accompanied by the formation of wrinkles. The theory is illustrated by examples.
Numerical Simulation of Two-dimensional Nonlinear Sloshing Problems
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
Numerical simulation of a two-dimensional nonlinearsloshing problem is preceded by the finite element method. Two theories are used. One is fully nonlinear theory; the other is time domain second order theory. A liquid sloshing in a rectangular container subjected to a horizontal excitation is simulated using these two theories. Numerical results are obtained and comparisons are made. It is found that a good agreement is obtained for the case of small amplitude oscillation. For the situation of large amplitude excitation, although the differences between using the two theories are obvious the second order solution can still exhibit typical nonlinear features of nonlinear wave.
Finite Element Analysis to Two-Dimensional Nonlinear Sloshing Problems
Institute of Scientific and Technical Information of China (English)
严承华; 王赤忠; 程尔升
2001-01-01
A two-dimensional nonlinear sloshing problem is analyzed by means of the fully nonlinear theory and time domainsecond order theory of water waves. Liquid sloshing in a rectangular container subjected to a horizontal excitation is sim-ulated by the finite element method. Comparisons between the two theories are made based on their numerical results. Itis found that good agreement is obtained for the case of small amplitude oscillation and obvious differences occur forlarge amplitude excitation. Even though, the second order solution can still exhibit typical nonlinear features ofnonlinear wave and can be used instead of the fully nonlinear theory.
The problem of friction in two-dimensional relative motion
Grech, D K; Grech, Dariusz; Mazur, Zygmunt
2000-01-01
We analyse a mechanical system in two-dimensional relative motion with friction. Although the system is simple, the peculiar interplay between two kinetic friction forces and gravity leads to the wide range of admissible solutions exceeding most intuitive expectations. In particular, the strong qualitative dependence between behaviour of the system, boundary conditions and parameters involved in its description is emphasised. The problem is intended to be discussed in theoretical framework and might be of interest for physics and mechanics students as well as for physics teachers.
Vibrational wave packet induced oscillations in two-dimensional electronic spectra. I. Experiments
Nemeth, Alexandra; Mancal, Tomas; Lukes, Vladimir; Hauer, Juergen; Kauffmann, Harald F; Sperling, Jaroslaw
2010-01-01
This is the first in a series of two papers investigating the effect of electron-phonon coupling in two-dimensional Fourier transformed electronic spectroscopy. We present a series of one- and two-dimensional nonlinear spectroscopic techniques for studying a dye molecule in solution. Ultrafast laser pulse excitation of an electronic transition coupled to vibrational modes induces a propagating vibrational wave packet that manifests itself in oscillating signal intensities and line-shapes. For the two-dimensional electronic spectra we can attribute the observed modulations to periodic enhancement and decrement of the relative amplitudes of rephasing and non-rephasing contributions to the total response. Different metrics of the two-dimensional signals are shown to relate to the frequency-frequency correlation function which provides the connection between experimentally accessible observations and the underlying microscopic molecular dynamics. A detailed theory of the time-dependent two-dimensional spectral li...
Nonclassical Symmetry Analysis of Heated Two-Dimensional Flow Problems
Naeem, Imran; Naz, Rehana; Khan, Muhammad Danish
2015-12-01
This article analyses the nonclassical symmetries and group invariant solution of boundary layer equations for two-dimensional heated flows. First, we derive the nonclassical symmetry determining equations with the aid of the computer package SADE. We solve these equations directly to obtain nonclassical symmetries. We follow standard procedure of computing nonclassical symmetries and consider two different scenarios, ξ1≠0 and ξ1=0, ξ2≠0. Several nonclassical symmetries are reported for both scenarios. Furthermore, numerous group invariant solutions for nonclassical symmetries are derived. The similarity variables associated with each nonclassical symmetry are computed. The similarity variables reduce the system of partial differential equations (PDEs) to a system of ordinary differential equations (ODEs) in terms of similarity variables. The reduced system of ODEs are solved to obtain group invariant solution for governing boundary layer equations for two-dimensional heated flow problems. We successfully formulate a physical problem of heat transfer analysis for fluid flow over a linearly stretching porous plat and, with suitable boundary conditions, we solve this problem.
Two-dimensional gauge theoretic supergravities
Cangemi, D.; Leblanc, M.
1994-05-01
We investigate two-dimensional supergravity theories, which can be built from a topological and gauge invariant action defined on an ordinary surface. One is the N = 1 supersymmetric extension of the Jackiw-Teitelboim model presented by Chamseddine in a superspace formalism. We complement the proof of Montano, Aoaki and Sonnenschein that this extension is topological and gauge invariant, based on the graded de Sitter algebra. Not only do the equations of motion correspond to the supergravity ones and do gauge transformations encompass local supersymmetries, but we also identify the ∫-theory with the superfield formalism action written by Chamseddine. Next, we show that the N = 1 supersymmetric extension of string-inspired two-dimensional dilaton gravity put forward by Park and Strominger cannot be written as a ∫-theory. As an alternative, we propose two topological and gauge theories that are based on a graded extension of the extended Poincaré algebra and satisfy a vanishing-curvature condition. Both models are supersymmetric extensions of the string-inspired dilaton gravity.
Two-Dimensional Theory of Scientific Representation
Directory of Open Access Journals (Sweden)
A Yaghmaie
2013-03-01
Full Text Available Scientific representation is an interesting topic for philosophers of science, many of whom have recently explored it from different points of view. There are currently two competing approaches to the issue: cognitive and non-cognitive, and each of them claims its own merits over the other. This article tries to provide a hybrid theory of scientific representation, called Two-Dimensional Theory of Scientific Representation, which has the merits of the two accounts and is free of their shortcomings. To do this, we will argue that although scientific representation needs to use the notion of intentionality, such a notion is defined and realized in a simply structural form contrary to what cognitive approach says about intentionality. After a short introduction, the second part of the paper is devoted to introducing theories of scientific representation briefly. In the third part, the structural accounts of representation will be criticized. The next step is to introduce the two-dimensional theory which involves two key components: fixing and structural fitness. It will be argued that fitness is an objective and non-intentional relation, while fixing is intentional.
Two-dimensional shape memory graphene oxide
Chang, Zhenyue; Deng, Junkai; Chandrakumara, Ganaka G.; Yan, Wenyi; Liu, Jefferson Zhe
2016-06-01
Driven by the increasing demand for micro-/nano-technologies, stimuli-responsive shape memory materials at nanoscale have recently attracted great research interests. However, by reducing the size of conventional shape memory materials down to approximately nanometre range, the shape memory effect diminishes. Here, using density functional theory calculations, we report the discovery of a shape memory effect in a two-dimensional atomically thin graphene oxide crystal with ordered epoxy groups, namely C8O. A maximum recoverable strain of 14.5% is achieved as a result of reversible phase transition between two intrinsically stable phases. Our calculations conclude co-existence of the two stable phases in a coherent crystal lattice, giving rise to the possibility of constructing multiple temporary shapes in a single material, thus, enabling highly desirable programmability. With an atomic thickness, excellent shape memory mechanical properties and electric field stimulus, the discovery of a two-dimensional shape memory graphene oxide opens a path for the development of exceptional micro-/nano-electromechanical devices.
Institute of Scientific and Technical Information of China (English)
XU Quan; TIAN Qiang
2007-01-01
Two-dimensional compact-like discrete breathers in discrete two-dimensional monatomic square lattices are investigated by discussing a generafized discrete two-dimensional monatomic model.It is proven that the twodimensional compact-like discrete breathers exist not only in two-dimensional soft Ф4 potentials but also in hard two-dimensional Ф4 potentials and pure two-dimensional K4 lattices.The measurements of the two-dimensional compact-like discrete breather cores in soft and hard two-dimensional Ф4 potential are determined by coupling parameter K4,while those in pure two-dimensional K4 lattices have no coupling with parameter K4.The stabilities of the two-dimensional compact-like discrete breathers correlate closely to the coupling parameter K4 and the boundary condition of lattices.
Bandoli, Giuliano; Nicolini, Marino; Pappalardo, Giuseppe C.; Grassi, Antonio; Perly, Bruno
1987-04-01
The crystal and molecular structure of the nootropic agent N-[2-( N,N-diisopropyl-amino)ethyl]-2-oxo-1-pyrrolidinacetamide sulphate was determined by X-ray analysis. The conformational properties in the solution state were deduced from the 1H-NMR spectrum run in 2H 2O at 500 MHz. Spectral assignments were made with the aid of the COSY 45 shift correlation experiment. Crystals were triclinic with unit cell dimensions a = 13.410(10), b = 11.382(8), c = 6.697(4) », α = 83.80(3), β = 88.61(3)and γ = 72.25(6)° ; space group Poverline1. The structure was determined from 1047 three-dimensional counter data and refined to a value of 7.5% for the conventional discrepancy factor R. One molecule of the solvent acetonitrile is incorporated per two of the (C 14H 28N 3O 2) +-(HSO 4) -. The five-membered heterocyclic ring is in an envelope ( Cs) conformation and the "flap" atom deviates by 0.31 » from the plane of the other four. This plane forms a dihedral angle of 71.4° with the amide group, with the CO fragment directed toward the ring. All bond angles and distances are in good agreement with expected standard values. A strong OH⋯O intermolecular bond (2.61 ») links the cation of the hydrogen-sulphate anion, while the loosely held MeCN molecule is trapped in the polar pockets. The molecular conformation in the solid was compared with results from 1H NMR spectral analysis which showed that in solution wide torsional oscillations can occur about the bonds of the chain bonded to the N(1) atom.
Optimal excitation of two dimensional Holmboe instabilities
Constantinou, Navid C
2010-01-01
Highly stratified shear layers are rendered unstable even at high stratifications by Holmboe instabilities when the density stratification is concentrated in a small region of the shear layer. These instabilities may cause mixing in highly stratified environments. However these instabilities occur in tongues for a limited range of parameters. We perform Generalized Stability analysis of the two dimensional perturbation dynamics of an inviscid Boussinesq stratified shear layer and show that Holmboe instabilities at high Richardson numbers can be excited by their adjoints at amplitudes that are orders of magnitude larger than by introducing initially the unstable mode itself. We also determine the optimal growth that obtains for parameters for which there is no instability. We find that there is potential for large transient growth regardless of whether the background flow is exponentially stable or not and that the characteristic structure of the Holmboe instability asymptotically emerges for parameter values ...
Probabilistic Universality in two-dimensional Dynamics
Lyubich, Mikhail
2011-01-01
In this paper we continue to explore infinitely renormalizable H\\'enon maps with small Jacobian. It was shown in [CLM] that contrary to the one-dimensional intuition, the Cantor attractor of such a map is non-rigid and the conjugacy with the one-dimensional Cantor attractor is at most 1/2-H\\"older. Another formulation of this phenomenon is that the scaling structure of the H\\'enon Cantor attractor differs from its one-dimensional counterpart. However, in this paper we prove that the weight assigned by the canonical invariant measure to these bad spots tends to zero on microscopic scales. This phenomenon is called {\\it Probabilistic Universality}. It implies, in particular, that the Hausdorff dimension of the canonical measure is universal. In this way, universality and rigidity phenomena of one-dimensional dynamics assume a probabilistic nature in the two-dimensional world.
Two-dimensional position sensitive neutron detector
Indian Academy of Sciences (India)
A M Shaikh; S S Desai; A K Patra
2004-08-01
A two-dimensional position sensitive neutron detector has been developed. The detector is a 3He + Kr filled multiwire proportional counter with charge division position readout and has a sensitive area of 345 mm × 345 mm, pixel size 5 mm × 5 mm, active depth 25 mm and is designed for efficiency of 70% for 4 Å neutrons. The detector is tested with 0.5 bar 3He + 1.5 bar krypton gas mixture in active chamber and 2 bar 4He in compensating chamber. The pulse height spectrum recorded at an anode potential of 2000 V shows energy resolution of ∼ 25% for the 764 keV peak. A spatial resolution of 8 mm × 6 mm is achieved. The detector is suitable for SANS studies in the range of 0.02–0.25 Å-1.
Two-dimensional heterostructures for energy storage
Pomerantseva, Ekaterina; Gogotsi, Yury
2017-07-01
Two-dimensional (2D) materials provide slit-shaped ion diffusion channels that enable fast movement of lithium and other ions. However, electronic conductivity, the number of intercalation sites, and stability during extended cycling are also crucial for building high-performance energy storage devices. While individual 2D materials, such as graphene, show some of the required properties, none of them can offer all properties needed to maximize energy density, power density, and cycle life. Here we argue that stacking different 2D materials into heterostructured architectures opens an opportunity to construct electrodes that would combine the advantages of the individual building blocks while eliminating the associated shortcomings. We discuss characteristics of common 2D materials and provide examples of 2D heterostructured electrodes that showed new phenomena leading to superior electrochemical performance. We also consider electrode fabrication approaches and finally outline future steps to create 2D heterostructured electrodes that could greatly expand current energy storage technologies.
Rationally synthesized two-dimensional polymers.
Colson, John W; Dichtel, William R
2013-06-01
Synthetic polymers exhibit diverse and useful properties and influence most aspects of modern life. Many polymerization methods provide linear or branched macromolecules, frequently with outstanding functional-group tolerance and molecular weight control. In contrast, extending polymerization strategies to two-dimensional periodic structures is in its infancy, and successful examples have emerged only recently through molecular framework, surface science and crystal engineering approaches. In this Review, we describe successful 2D polymerization strategies, as well as seminal research that inspired their development. These methods include the synthesis of 2D covalent organic frameworks as layered crystals and thin films, surface-mediated polymerization of polyfunctional monomers, and solid-state topochemical polymerizations. Early application targets of 2D polymers include gas separation and storage, optoelectronic devices and membranes, each of which might benefit from predictable long-range molecular organization inherent to this macromolecular architecture.
Janus Spectra in Two-Dimensional Flows
Liu, Chien-Chia; Cerbus, Rory T.; Chakraborty, Pinaki
2016-09-01
In large-scale atmospheric flows, soap-film flows, and other two-dimensional flows, the exponent of the turbulent energy spectra, α , may theoretically take either of two distinct values, 3 or 5 /3 , but measurements downstream of obstacles have invariably revealed α =3 . Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which α transitions from 3 to 5 /3 for the streamwise fluctuations but remains equal to 3 for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows.
Local doping of two-dimensional materials
Wong, Dillon; Velasco, Jr, Jairo; Ju, Long; Kahn, Salman; Lee, Juwon; Germany, Chad E.; Zettl, Alexander K.; Wang, Feng; Crommie, Michael F.
2016-09-20
This disclosure provides systems, methods, and apparatus related to locally doping two-dimensional (2D) materials. In one aspect, an assembly including a substrate, a first insulator disposed on the substrate, a second insulator disposed on the first insulator, and a 2D material disposed on the second insulator is formed. A first voltage is applied between the 2D material and the substrate. With the first voltage applied between the 2D material and the substrate, a second voltage is applied between the 2D material and a probe positioned proximate the 2D material. The second voltage between the 2D material and the probe is removed. The first voltage between the 2D material and the substrate is removed. A portion of the 2D material proximate the probe when the second voltage was applied has a different electron density compared to a remainder of the 2D material.
Two-dimensional fourier transform spectrometer
Energy Technology Data Exchange (ETDEWEB)
DeFlores, Lauren; Tokmakoff, Andrei
2016-10-25
The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.
Two-dimensional fourier transform spectrometer
DeFlores, Lauren; Tokmakoff, Andrei
2013-09-03
The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.
FACE RECOGNITION USING TWO DIMENSIONAL LAPLACIAN EIGENMAP
Institute of Scientific and Technical Information of China (English)
Chen Jiangfeng; Yuan Baozong; Pei Bingnan
2008-01-01
Recently,some research efforts have shown that face images possibly reside on a nonlinear sub-manifold. Though Laplacianfaces method considered the manifold structures of the face images,it has limits to solve face recognition problem. This paper proposes a new feature extraction method,Two Dimensional Laplacian EigenMap (2DLEM),which especially considers the manifold structures of the face images,and extracts the proper features from face image matrix directly by using a linear transformation. As opposed to Laplacianfaces,2DLEM extracts features directly from 2D images without a vectorization preprocessing. To test 2DLEM and evaluate its performance,a series of ex-periments are performed on the ORL database and the Yale database. Moreover,several experiments are performed to compare the performance of three 2D methods. The experiments show that 2DLEM achieves the best performance.
Equivalency of two-dimensional algebras
Energy Technology Data Exchange (ETDEWEB)
Santos, Gildemar Carneiro dos; Pomponet Filho, Balbino Jose S. [Universidade Federal da Bahia (UFBA), BA (Brazil). Inst. de Fisica
2011-07-01
Full text: Let us consider a vector z = xi + yj over the field of real numbers, whose basis (i,j) satisfy a given algebra. Any property of this algebra will be reflected in any function of z, so we can state that the knowledge of the properties of an algebra leads to more general conclusions than the knowledge of the properties of a function. However structural properties of an algebra do not change when this algebra suffers a linear transformation, though the structural constants defining this algebra do change. We say that two algebras are equivalent to each other whenever they are related by a linear transformation. In this case, we have found that some relations between the structural constants are sufficient to recognize whether or not an algebra is equivalent to another. In spite that the basis transform linearly, the structural constants change like a third order tensor, but some combinations of these tensors result in a linear transformation, allowing to write the entries of the transformation matrix as function of the structural constants. Eventually, a systematic way to find the transformation matrix between these equivalent algebras is obtained. In this sense, we have performed the thorough classification of associative commutative two-dimensional algebras, and find that even non-division algebra may be helpful in solving non-linear dynamic systems. The Mandelbrot set was used to have a pictorial view of each algebra, since equivalent algebras result in the same pattern. Presently we have succeeded in classifying some non-associative two-dimensional algebras, a task more difficult than for associative one. (author)
DEFF Research Database (Denmark)
Monti, Susanna; Corozzi, Alessandro; Fristrup, Peter
2013-01-01
reported glycine parameters. This expansion consists of adding to the training set more than five hundred molecular systems, including all the amino acids and some short peptide structures, which have been investigated by means of quantum mechanical calculations. The performance of this ReaxFF protein...... force field on a relatively short time scale (500 ps) is validated by comparison with classical non-reactive simulations and experimental data of well characterized test cases, comprising capped amino acids, peptides, and small proteins, and reaction mechanisms connected to the pharmaceutical sector......In order to describe possible reaction mechanisms involving amino acids, and the evolution of the protonation state of amino acid side chains in solution, a reactive force field (ReaxFF-based description) for peptide and protein simulations has been developed as an expansion of the previously...
Oriented Two-Dimensional Porous Organic Cage Crystals.
Jiang, Shan; Song, Qilei; Massey, Alan; Chong, Samantha Y; Chen, Linjiang; Sun, Shijing; Hasell, Tom; Raval, Rasmita; Sivaniah, Easan; Cheetham, Anthony K; Cooper, Andrew I
2017-08-01
The formation of two-dimensional (2D) oriented porous organic cage crystals (consisting of imine-based tetrahedral molecules) on various substrates (such as silicon wafers and glass) by solution-processing is reported. Insight into the crystallinity, preferred orientation, and cage crystal growth was obtained by experimental and computational techniques. For the first time, structural defects in porous molecular materials were observed directly and the defect concentration could be correlated with crystal growth rate. These oriented crystals suggest potential for future applications, such as solution-processable molecular crystalline 2D membranes for molecular separations. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
Kinks in two-dimensional Anti-de Sitter Space
Barnes, J L; ter Veldhuis, T; Webster, M J
2009-01-01
Soliton solutions in scalar field theory defined on a two-dimensional Anti-de Sitter background space-time are investigated. It is shown that the lowest soliton excitation generically has frequency equal to the inverse radius of the space-time. Analytic and numerical soliton solutions are determined in "phi to the fourth" scalar field theory with a negative mass-squared. The classical soliton mass is calculated as a function of the ratio of the square of the mass scale of the field theory over the curvature of the space-time. For the case that this ratio equals unity, the soliton excitation spectrum is determined algebraically and the one-loop radiative correction to the soliton mass is computed in the semi-classical approximation.
The modified cumulant expansion for two-dimensional isotropic turbulence
Tatsumi, T.; Yanase, S.
1981-09-01
The two-dimensional isotropic turbulence in an incompressible fluid is investigated using the modified zero fourth-order cumulant approximation. The dynamical equation for the energy spectrum obtained under this approximation is solved numerically and the similarity laws governing the solution in the energy-containing and enstrophy-dissipation ranges are derived analytically. At large Reynolds numbers the numerical solutions yield the k to the -3rd power inertial subrange spectrum which was predicted by Kraichnan (1967), Leith (1968) and Batchelor (1969), assuming a finite enstrophy dissipation in the inviscid limit. The energy-containing range is found to satisfy an inviscid similarity while the enstrophy-dissipation range is governed by the quasi-equilibrium similarity with respect to the enstrophy dissipation as proposed by Batchelor (1969). There exists a critical time which separates the initial period and the similarity period in which the enstrophy dissipation vanishes and remains non-zero respectively in the inviscid limit.
On numerical evaluation of two-dimensional phase integrals
DEFF Research Database (Denmark)
Lessow, H.; Rusch, W.; Schjær-Jacobsen, Hans
1975-01-01
The relative advantages of several common numerical integration algorithms used in computing two-dimensional phase integrals are evaluated.......The relative advantages of several common numerical integration algorithms used in computing two-dimensional phase integrals are evaluated....
Janus spectra in two-dimensional flows
Liu, Chien-Chia; Chakraborty, Pinaki
2016-01-01
In theory, large-scale atmospheric flows, soap-film flows and other two-dimensional flows may host two distinct types of turbulent energy spectra---in one, $\\alpha$, the spectral exponent of velocity fluctuations, equals $3$ and the fluctuations are dissipated at the small scales, and in the other, $\\alpha=5/3$ and the fluctuations are dissipated at the large scales---but measurements downstream of obstacles have invariably revealed $\\alpha = 3$. Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which $\\alpha$ has transitioned from $3$ to $5/3$ for the streamwise fluctuations but remains equal to $3$ for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows...
Comparative Two-Dimensional Fluorescence Gel Electrophoresis.
Ackermann, Doreen; König, Simone
2018-01-01
Two-dimensional comparative fluorescence gel electrophoresis (CoFGE) uses an internal standard to increase the reproducibility of coordinate assignment for protein spots visualized on 2D polyacrylamide gels. This is particularly important for samples, which need to be compared without the availability of replicates and thus cannot be studied using differential gel electrophoresis (DIGE). CoFGE corrects for gel-to-gel variability by co-running with the sample proteome a standardized marker grid of 80-100 nodes, which is formed by a set of purified proteins. Differentiation of reference and analyte is possible by the use of two fluorescent dyes. Variations in the y-dimension (molecular weight) are corrected by the marker grid. For the optional control of the x-dimension (pI), azo dyes can be used. Experiments are possible in both vertical and horizontal (h) electrophoresis devices, but hCoFGE is much easier to perform. For data analysis, commercial software capable of warping can be adapted.
Two-dimensional hexagonal semiconductors beyond graphene
Nguyen, Bich Ha; Hieu Nguyen, Van
2016-12-01
The rapid and successful development of the research on graphene and graphene-based nanostructures has been substantially enlarged to include many other two-dimensional hexagonal semiconductors (THS): phosphorene, silicene, germanene, hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMDCs) such as MoS2, MoSe2, WS2, WSe2 as well as the van der Waals heterostructures of various THSs (including graphene). The present article is a review of recent works on THSs beyond graphene and van der Waals heterostructures composed of different pairs of all THSs. One among the priorities of new THSs compared to graphene is the presence of a non-vanishing energy bandgap which opened up the ability to fabricate a large number of electronic, optoelectronic and photonic devices on the basis of these new materials and their van der Waals heterostructures. Moreover, a significant progress in the research on TMDCs was the discovery of valley degree of freedom. The results of research on valley degree of freedom and the development of a new technology based on valley degree of freedom-valleytronics are also presented. Thus the scientific contents of the basic research and practical applications os THSs are very rich and extremely promising.
Two-Dimensional Phononic Crystals: Disorder Matters.
Wagner, Markus R; Graczykowski, Bartlomiej; Reparaz, Juan Sebastian; El Sachat, Alexandros; Sledzinska, Marianna; Alzina, Francesc; Sotomayor Torres, Clivia M
2016-09-14
The design and fabrication of phononic crystals (PnCs) hold the key to control the propagation of heat and sound at the nanoscale. However, there is a lack of experimental studies addressing the impact of order/disorder on the phononic properties of PnCs. Here, we present a comparative investigation of the influence of disorder on the hypersonic and thermal properties of two-dimensional PnCs. PnCs of ordered and disordered lattices are fabricated of circular holes with equal filling fractions in free-standing Si membranes. Ultrafast pump and probe spectroscopy (asynchronous optical sampling) and Raman thermometry based on a novel two-laser approach are used to study the phononic properties in the gigahertz (GHz) and terahertz (THz) regime, respectively. Finite element method simulations of the phonon dispersion relation and three-dimensional displacement fields furthermore enable the unique identification of the different hypersonic vibrations. The increase of surface roughness and the introduction of short-range disorder are shown to modify the phonon dispersion and phonon coherence in the hypersonic (GHz) range without affecting the room-temperature thermal conductivity. On the basis of these findings, we suggest a criteria for predicting phonon coherence as a function of roughness and disorder.
Two-dimensional topological photonic systems
Sun, Xiao-Chen; He, Cheng; Liu, Xiao-Ping; Lu, Ming-Hui; Zhu, Shi-Ning; Chen, Yan-Feng
2017-09-01
The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research topic worldwide. So far, many bosonic topological models and methods for realizing them have been discovered in photonic systems, acoustic systems, mechanical systems, etc. These discoveries have certainly yielded vast opportunities in designing material phases and related properties in the topological domain. In this review, we first focus on some of the representative photonic topological models and employ the underlying Dirac model to analyze the edge states and geometric phase. On the basis of these models, three common types of two-dimensional topological photonic systems are discussed: 1) photonic quantum Hall effect with broken time-reversal symmetry; 2) photonic topological insulator and the associated pseudo-time-reversal symmetry-protected mechanism; 3) time/space periodically modulated photonic Floquet topological insulator. Finally, we provide a summary and extension of this emerging field, including a brief introduction to the Weyl point in three-dimensional systems.
Radiation effects on two-dimensional materials
Energy Technology Data Exchange (ETDEWEB)
Walker, R.C. II; Robinson, J.A. [Department of Materials Science, Penn State, University Park, PA (United States); Center for Two-Dimensional Layered Materials, Penn State, University Park, PA (United States); Shi, T. [Department of Mechanical and Nuclear Engineering, Penn State, University Park, PA (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States); Silva, E.C. [GlobalFoundries, Malta, NY (United States); Jovanovic, I. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States)
2016-12-15
The effects of electromagnetic and particle irradiation on two-dimensional materials (2DMs) are discussed in this review. Radiation creates defects that impact the structure and electronic performance of materials. Determining the impact of these defects is important for developing 2DM-based devices for use in high-radiation environments, such as space or nuclear reactors. As such, most experimental studies have been focused on determining total ionizing dose damage to 2DMs and devices. Total dose experiments using X-rays, gamma rays, electrons, protons, and heavy ions are summarized in this review. We briefly discuss the possibility of investigating single event effects in 2DMs based on initial ion beam irradiation experiments and the development of 2DM-based integrated circuits. Additionally, beneficial uses of irradiation such as ion implantation to dope materials or electron-beam and helium-beam etching to shape materials have begun to be used on 2DMs and are reviewed as well. For non-ionizing radiation, such as low-energy photons, we review the literature on 2DM-based photo-detection from terahertz to UV. The majority of photo-detecting devices operate in the visible and UV range, and for this reason they are the focus of this review. However, we review the progress in developing 2DMs for detecting infrared and terahertz radiation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Photodetectors based on two dimensional materials
Zheng, Lou; Zhongzhu, Liang; Guozhen, Shen
2016-09-01
Two-dimensional (2D) materials with unique properties have received a great deal of attention in recent years. This family of materials has rapidly established themselves as intriguing building blocks for versatile nanoelectronic devices that offer promising potential for use in next generation optoelectronics, such as photodetectors. Furthermore, their optoelectronic performance can be adjusted by varying the number of layers. They have demonstrated excellent light absorption, enabling ultrafast and ultrasensitive detection of light in photodetectors, especially in their single-layer structure. Moreover, due to their atomic thickness, outstanding mechanical flexibility, and large breaking strength, these materials have been of great interest for use in flexible devices and strain engineering. Toward that end, several kinds of photodetectors based on 2D materials have been reported. Here, we present a review of the state-of-the-art in photodetectors based on graphene and other 2D materials, such as the graphene, transition metal dichalcogenides, and so on. Project supported by the National Natural Science Foundation of China (Nos. 61377033, 61574132, 61504136) and the State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences.
Asymptotics for Two-dimensional Atoms
DEFF Research Database (Denmark)
Nam, Phan Thanh; Portmann, Fabian; Solovej, Jan Philip
2012-01-01
We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E^{\\TF}(\\lambd......We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E......^{\\TF}(\\lambda)$ is given by a Thomas-Fermi type variational problem and $c^{\\rm H}\\approx -2.2339$ is an explicit constant. We also show that the radius of a two-dimensional neutral atom is unbounded when $Z\\to \\infty$, which is contrary to the expected behavior of three-dimensional atoms....
Predicting Two-Dimensional Silicon Carbide Monolayers.
Shi, Zhiming; Zhang, Zhuhua; Kutana, Alex; Yakobson, Boris I
2015-10-27
Intrinsic semimetallicity of graphene and silicene largely limits their applications in functional devices. Mixing carbon and silicon atoms to form two-dimensional (2D) silicon carbide (SixC1-x) sheets is promising to overcome this issue. Using first-principles calculations combined with the cluster expansion method, we perform a comprehensive study on the thermodynamic stability and electronic properties of 2D SixC1-x monolayers with 0 ≤ x ≤ 1. Upon varying the silicon concentration, the 2D SixC1-x presents two distinct structural phases, a homogeneous phase with well dispersed Si (or C) atoms and an in-plane hybrid phase rich in SiC domains. While the in-plane hybrid structure shows uniform semiconducting properties with widely tunable band gap from 0 to 2.87 eV due to quantum confinement effect imposed by the SiC domains, the homogeneous structures can be semiconducting or remain semimetallic depending on a superlattice vector which dictates whether the sublattice symmetry is topologically broken. Moreover, we reveal a universal rule for describing the electronic properties of the homogeneous SixC1-x structures. These findings suggest that the 2D SixC1-x monolayers may present a new "family" of 2D materials, with a rich variety of properties for applications in electronics and optoelectronics.
Two-Dimensional turbulence in the inverse cascade range
Yakhot, V
1999-01-01
A theory of two-dimensional turbulence in the inverse energy cascade range is presented. Strong time-dependence of the large-scale features of the flow ($\\bar{u^{2}}\\propto t$) results in decoupling of the large-scale dynamics from statistically steady-state small-scale random processes. This time-dependence is also a reason for the localness of the pressure-gradient terms in the equations governing the small-scale velocity difference PDF's. The derived expressions for the pressure gradient contributions lead to a gaussian statistics of transverse velocity differences. The solution for the PDF of longitudinal velocity differences is based on a smallness of the energy flux in two-dimensional turbulence. The theory makes a few quantitative predictions which can be tested experimentally. One of the most surprising results, derived in this paper, is that the small-scale transverse velocity differences are governed by a linear Langevin-like equation, strirred by a non-local universal gaussian random force. This ex...
De Gaspari, Francesca; Cabeza, Yoar; Luquot, Linda; Rötting, Tobias; Saaltink, Maarten W.; Carrera, Jesus
2014-05-01
Several field tests will be carried out in order to characterize the reservoir for CO2 injection in Hontomín (Burgos, Spain) as part of the Compostilla project of "Fundación Ciudad de la Energía" (CIUDEN). Once injected, the dissolution of the CO2 in the resident brine will increase the acidity of the water and lead to the dissolution of the rocks, constituted mainly by carbonates. This mechanism will cause changes in the aquifer properties such as porosity and permeability. To reproduce the effect of the CO2 injection, a reactive solution with 2% of acetic acid is going to be injected in the reservoir and extracted from the same well (reactive "push-pull" tracer tests) to identify and quantify the geochemical reactions occurring into the aquifer. The reactivity of the rock will allow us also to evaluate the changes of its properties. Previously, theoretical calculations of Damkhöler numbers were done to determine the acid concentrations and injection flow rates needed to generate ramified-wormholes patterns, during theses "push-pull" experiments. The aim of this work is to present the results and a preliminary interpretation of the field tests.
Electronic nanobiosensors based on two-dimensional materials
Ping, Jinglei
Atomically-thick two-dimensional (2D) nanomaterials have tremendous potential to be applied as transduction elements in biosensors and bioelectronics. We developed scalable methods for synthesis and large-area transfer of two-dimensional nanomaterials, particularly graphene and metal dichalcogenides (so called ``MX2'' materials). We also developed versatile fabrication methods for large arrays of field-effect transistors (FETs) and micro-electrodes with these nanomaterials based on either conventional photolithography or innovative approaches that minimize contamination of the 2D layer. By functionalizing the FETs with a computationally redesigned water-soluble mu-opioid receptor, we created selective and sensitive biosensors suitable for detection of the drug target naltrexone and the neuropeptide enkephalin at pg/mL concentrations. We also constructed DNA-functionalized biosensors and nano-particle decorated biosensors by applying related bio-nano integration techniques. Our methodology paves the way for multiplexed nanosensor arrays with all-electronic readout suitable for inexpensive point-of-care diagnostics, drug-development and biomedical research. With graphene field-effect transistors, we investigated the graphene/solution interface and developed a quantitative model for the effect of ionic screening on the graphene carrier density based on theories of the electric double layer. Finally, we have developed a technique for measuring low-level Faradaic charge-transfer current (fA) across the graphene/solution interface via real-time charge monitoring of graphene microelectrodes in ionic solution. This technique enables the development of flexible and transparent pH sensors that are promising for in vivo applications. The author acknowledges the support from the Defense Advanced Research Projects Agency (DARPA) and the U. S. Army Research Office under Grant Number W911NF1010093.
Bellebia, S; Kacha, S; Bouberka, Z; Bouyakoub, A Z; Derriche, Z
2009-04-01
In this study, electrocoagulation of Marine Blue Erionyl MR (acid dye) and electrocoagulation followed by adsorption of Brilliant Blue Levafix E-BRA (reactive dye) from aqueous solutions were investigated, using aluminum electrodes and granular activated carbon (GAC). In the electrocoagulation and adsorption of dyestuff solutions, the effects of current density, loading charge, pH, conductivity, stirring velocity, contact time, and GAC concentration were examined. The optimum conditions for the electrocoagulation process were identified as loading charges 7.46 and 1.49 F/m3, for a maximum abatement of 200 mg/L reactive and acid dye, respectively. The residual reactive dye concentration was completely removed with 700 mg/L GAC. The results of this investigation provide important data for the development of a combined process to remove significant concentrations of recalcitrant dyes from water, using moderate activated carbon energy and aluminum consumption, and thereby lowering the cost of treatment.
Interaction of two-dimensional magnetoexcitons
Dumanov, E. V.; Podlesny, I. V.; Moskalenko, S. A.; Liberman, M. A.
2017-04-01
We study interaction of the two-dimensional magnetoexcitons with in-plane wave vector k→∥ = 0 , taking into account the influence of the excited Landau levels (ELLs) and of the external electric field perpendicular to the surface of the quantum well and parallel to the external magnetic field. It is shown that the account of the ELLs gives rise to the repulsion between the spinless magnetoexcitons with k→∥ = 0 in the Fock approximation, with the interaction constant g decreasing inverse proportional to the magnetic field strength B (g (0) ∼ 1 / B) . In the presence of the perpendicular electric field the Rashba spin-orbit coupling (RSOC), Zeeman splitting (ZS) and nonparabolicity of the heavy-hole dispersion law affect the Landau quantization of the electrons and holes. They move along the new cyclotron orbits, change their Coulomb interactions and cause the interaction between 2D magnetoexcitons with k→∥ = 0 . The changes of the Coulomb interactions caused by the electrons and by the holes moving with new cyclotron orbits are characterized by some coefficients, which in the absence of the electric field turn to be unity. The differences between these coefficients of the electron-hole pairs forming the magnetoexcitons determine their affinities to the interactions. The interactions between the homogeneous, semihomogeneous and heterogeneous magnetoexcitons forming the symmetric states with the same signs of their affinities are attractive whereas in the case of different sign affinities are repulsive. In the heterogeneous asymmetric states the interactions have opposite signs in comparison with the symmetric states. In all these cases the interaction constant g have the dependence g (0) 1 /√{ B} .
All or nothing: On the small fluctuations of two-dimensional string theoretic black holes
Energy Technology Data Exchange (ETDEWEB)
Gilbert, Gerald [Univ. of Maryland, College Park, MD (United States); Raiten, Eric [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
1992-10-01
A comprehensive analysis of small fluctuations about two-dimensional string-theoretic and string-inspired black holes is presented. It is shown with specific examples that two-dimensional black holes behave in a radically different way from all known black holes in four dimensions. For both the SL(2,R)/U(1) black hole and the two-dimensional black hole coupled to a massive dilaton with constant field strength, it is shown that there are a {\\it continuous infinity} of solutions to the linearized equations of motion, which are such that it is impossible to ascertain the classical linear response. It is further shown that the two-dimensional black hole coupled to a massive, linear dilaton admits {\\it no small fluctuations at all}. We discuss possible implications of our results for the Callan-Giddings-Harvey-Strominger black hole.
Two-dimensional materials and their prospects in transistor electronics.
Schwierz, F; Pezoldt, J; Granzner, R
2015-05-14
During the past decade, two-dimensional materials have attracted incredible interest from the electronic device community. The first two-dimensional material studied in detail was graphene and, since 2007, it has intensively been explored as a material for electronic devices, in particular, transistors. While graphene transistors are still on the agenda, researchers have extended their work to two-dimensional materials beyond graphene and the number of two-dimensional materials under examination has literally exploded recently. Meanwhile several hundreds of different two-dimensional materials are known, a substantial part of them is considered useful for transistors, and experimental transistors with channels of different two-dimensional materials have been demonstrated. In spite of the rapid progress in the field, the prospects of two-dimensional transistors still remain vague and optimistic opinions face rather reserved assessments. The intention of the present paper is to shed more light on the merits and drawbacks of two-dimensional materials for transistor electronics and to add a few more facets to the ongoing discussion on the prospects of two-dimensional transistors. To this end, we compose a wish list of properties for a good transistor channel material and examine to what extent the two-dimensional materials fulfill the criteria of the list. The state-of-the-art two-dimensional transistors are reviewed and a balanced view of both the pros and cons of these devices is provided.
Dislocations in the second kind two-dimensional quasicrystals of soft matter
Li, X. F.; Fan, T. Y.
2016-12-01
This letter reports dislocations and solutions of the second kind two-dimensional quasicrystals of soft matter, and all solutions are analytic and in closed form, which provide a basis for the defect study of this kind of quasicrystals in soft matter.
A Solvable Model in Two-Dimensional Gravity Coupled to a Nonlinear Matter Field
Institute of Scientific and Technical Information of China (English)
YAN Jun; WANG Shun-Jin; TAO Bi-You
2001-01-01
The two-dimensional gravity model with a coupling constant k = 4 and a vanishing cosmological constant coupled to a nonlinear matter field is investigated. We found that the classical equations of motion are exactly solvable and the static solutions of the induced metric and scalar curvature can be obtained analytically. These solutions may be used to describe the naked singularity at the origin.``
Analysis of Two-Dimensional Electrophoresis Gel Images
DEFF Research Database (Denmark)
Pedersen, Lars
2002-01-01
This thesis describes and proposes solutions to some of the currently most important problems in pattern recognition and image analysis of two-dimensional gel electrophoresis (2DGE) images. 2DGE is the leading technique to separate individual proteins in biological samples with many biological...... the methods developed in the literature specifically for matching protein spot patterns, the focus is on a method based on neighbourhood relations. These methods are applied to a range of 2DGE protein spot data in a comparative study. The point pattern matching requires segmentation of the gel images...... and since the correct image segmentation can be difficult, a new alternative approach, exploiting prior knowledge from a reference gel about the protein locations to segment an incoming gel image, is proposed....
Two-dimensional wave propagation in layered periodic media
Quezada de Luna, Manuel
2014-09-16
We study two-dimensional wave propagation in materials whose properties vary periodically in one direction only. High order homogenization is carried out to derive a dispersive effective medium approximation. One-dimensional materials with constant impedance exhibit no effective dispersion. We show that a new kind of effective dispersion may arise in two dimensions, even in materials with constant impedance. This dispersion is a macroscopic effect of microscopic diffraction caused by spatial variation in the sound speed. We analyze this dispersive effect by using highorder homogenization to derive an anisotropic, dispersive effective medium. We generalize to two dimensions a homogenization approach that has been used previously for one-dimensional problems. Pseudospectral solutions of the effective medium equations agree to high accuracy with finite volume direct numerical simulations of the variable-coeffi cient equations.
Oscillation of Two-Dimensional Neutral Delay Dynamic Systems
Directory of Open Access Journals (Sweden)
Xinli Zhang
2013-01-01
Full Text Available We consider a class of nonlinear two-dimensional dynamic systems of the neutral type (x(t-a(tx(τ1(tΔ=p(tf1(y(t, yΔ(t=-q(tf2(x(τ2(t. We obtain sufficient conditions for all solutions of the system to be oscillatory. Our oscillation results when a(t=0 improve the oscillation results for dynamic systems on time scales that have been established by Fu and Lin (2010, since our results do not restrict to the case where f(u=u. Also, as a special case when =ℝ, our results do not require an to be a positive real sequence. Some examples are given to illustrate the main results.
Polarons and molecules in a two-dimensional Fermi gas
DEFF Research Database (Denmark)
Zöllner, Sascha; Bruun, Georg Morten; Pethick, C. J.
2011-01-01
We study an impurity atom in a two-dimensional Fermi gas using variational wave functions for (i) an impurity dressed by particle-hole excitations (polaron) and (ii) a dimer consisting of the impurity and a majority atom. In contrast to three dimensions, where similar calculations predict a sharp...... transition to a dimer state with increasing interspecies attraction, we show that the polaron Ansatz always gives a lower energy. However, the exact solution for a heavy impurity reveals that both a two-body bound state and distortions of the Fermi sea are crucial. This reflects the importance of particle......-hole pairs in lower dimensions and makes simple variational calculations unreliable. We show that the energy of an impurity gives important information about its dressing cloud, for which both Ansätze give inaccurate results....
Yang, Jianwen
2012-04-01
A general analytical solution is derived by using the Laplace transformation to describe transient reactive silica transport in a conceptualized 2-D system involving a set of parallel fractures embedded in an impermeable host rock matrix, taking into account of hydrodynamic dispersion and advection of silica transport along the fractures, molecular diffusion from each fracture to the intervening rock matrix, and dissolution of quartz. A special analytical solution is also developed by ignoring the longitudinal hydrodynamic dispersion term but remaining other conditions the same. The general and special solutions are in the form of a double infinite integral and a single infinite integral, respectively, and can be evaluated using Gauss-Legendre quadrature technique. A simple criterion is developed to determine under what conditions the general analytical solution can be approximated by the special analytical solution. It is proved analytically that the general solution always lags behind the special solution, unless a dimensionless parameter is less than a critical value. Several illustrative calculations are undertaken to demonstrate the effect of fracture spacing, fracture aperture and fluid flow rate on silica transport. The analytical solutions developed here can serve as a benchmark to validate numerical models that simulate reactive mass transport in fractured porous media.
Directory of Open Access Journals (Sweden)
M.S Uddin
2011-01-01
Full Text Available The paper is concerned to find the distribution of the chemically reactant solute in the MHD flow of an electrically conducting viscous incompressible fluid over a stretching surface. The first order chemical reaction and the variable solute distribution along the surface are taken into consideration. The governing partial differential equations along with appropriate boundary conditions for flow field and reactive solute are transformed into a set of non-linear self-similar ordinary differential equations by using scaling group of transformations. An exact analytic solution is obtained for the velocity field. Using this velocity field, we obtain numerical solution for the reactant concentration field. It reveals from the study that the values of concentration profile enhances with the increase of the magnetic field and decreases with increase of Schmidt number as well as the reaction rate parameter. Most importantly, when the solute distribution along the surface increases then the concentration profile decreases.
STABILITY OF SYSTEM OF TWO-DIMENSIONAL NON-HYDROSTATIC REVOLVING FLUIDS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Applying the theory of stratification, it is proved that the system of the two-dimensional non-hydrostatic revolving fluids is unstable in the two-order continuous function class. The construction of solution space is given and the solution approach is offered. The sufficient and necessary conditions of the existence of formal solutions are expressed for some typical initial and boundary value problems and the calculating formulae to formal solutions are presented in detail.
Molecular assembly on two-dimensional materials
Kumar, Avijit; Banerjee, Kaustuv; Liljeroth, Peter
2017-02-01
Molecular self-assembly is a well-known technique to create highly functional nanostructures on surfaces. Self-assembly on two-dimensional (2D) materials is a developing field driven by the interest in functionalization of 2D materials in order to tune their electronic properties. This has resulted in the discovery of several rich and interesting phenomena. Here, we review this progress with an emphasis on the electronic properties of the adsorbates and the substrate in well-defined systems, as unveiled by scanning tunneling microscopy. The review covers three aspects of the self-assembly. The first one focuses on non-covalent self-assembly dealing with site-selectivity due to inherent moiré pattern present on 2D materials grown on substrates. We also see that modification of intermolecular interactions and molecule–substrate interactions influences the assembly drastically and that 2D materials can also be used as a platform to carry out covalent and metal-coordinated assembly. The second part deals with the electronic properties of molecules adsorbed on 2D materials. By virtue of being inert and possessing low density of states near the Fermi level, 2D materials decouple molecules electronically from the underlying metal substrate and allow high-resolution spectroscopy and imaging of molecular orbitals. The moiré pattern on the 2D materials causes site-selective gating and charging of molecules in some cases. The last section covers the effects of self-assembled, acceptor and donor type, organic molecules on the electronic properties of graphene as revealed by spectroscopy and electrical transport measurements. Non-covalent functionalization of 2D materials has already been applied for their application as catalysts and sensors. With the current surge of activity on building van der Waals heterostructures from atomically thin crystals, molecular self-assembly has the potential to add an extra level of flexibility and functionality for applications ranging
Semianalytical Solutions of Radioactive or Reactive Tracer Transport in Layered Fractured Media
Energy Technology Data Exchange (ETDEWEB)
G.J. Moridis; G. S. Bodvarsson
2001-10-01
In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive tracers (solutes or colloids) through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the matrix account for (a) diffusion, (b) surface diffusion (for solutes only), (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first order chemical reactions. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Additionally, the colloid transport equations account for straining and velocity adjustments related to the colloidal size. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity. {sup 239}Pu colloid transport problems in multilayered systems indicate significant colloid accumulations at straining interfaces but much faster transport of the colloid than the corresponding strongly sorbing solute species.
Semianalytical solutions of radioactive or reactive tracer transport in layered fractured media
Energy Technology Data Exchange (ETDEWEB)
Moridis, G.J.; Bodvarsson, G.S.
2001-10-10
In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive tracers (solutes or colloids) through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the matrix account for (a) diffusion, (b) surface diffusion (for solutes only), (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first order chemical reactions. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Additionally, the colloid transport equations account for straining and velocity adjustments related to the colloidal size. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity. {sup 239}Pu colloid transport problems in multilayered systems indicate significant colloid accumulations at straining interfaces but much faster transport of the colloid than the corresponding strongly sorbing solute species.
The convolution theorem for two-dimensional continuous wavelet transform
Institute of Scientific and Technical Information of China (English)
ZHANG CHI
2013-01-01
In this paper , application of two -dimensional continuous wavelet transform to image processes is studied. We first show that the convolution and correlation of two continuous wavelets satisfy the required admissibility and regularity conditions ,and then we derive the convolution and correlation theorem for two-dimensional continuous wavelet transform. Finally, we present numerical example showing the usefulness of applying the convolution theorem for two -dimensional continuous wavelet transform to perform image restoration in the presence of additive noise.
Two-Dimensional Einstein Manifolds in Geometrothermodynamics
Directory of Open Access Journals (Sweden)
Antonio C. Gutiérrez-Piñeres
2013-01-01
Full Text Available We present a class of thermodynamic systems with constant thermodynamic curvature which, within the context of geometric approaches of thermodynamics, can be interpreted as constant thermodynamic interaction among their components. In particular, for systems constrained by the vanishing of the Hessian curvature we write down the systems of partial differential equations. In such a case it is possible to find a subset of solutions lying on a circumference in an abstract space constructed from the first derivatives of the isothermal coordinates. We conjecture that solutions on the characteristic circumference are of physical relevance, separating them from those of pure mathematical interest. We present the case of a one-parameter family of fundamental relations that—when lying in the circumference—describe a polytropic fluid.
Institute of Scientific and Technical Information of China (English)
Chandaneswar Midya
2012-01-01
An analytical study of the distribution of a reactant solute undergoing a first-order chemical reaction in the boundary layer flow of an electrically conducting incompressible Buid over a linearly shrinking surface is presented. The Row is permeated by an externally applied magnetic Geld normal to the plane of the flow. The equations governing the Row and concentration Reid are reduced into a set of nonlinear ordinary differential equations using similarity variables. Closed form exact solutions of the reduced concentration equation are obtained for both prescribed power-law surface concentration (PSC) and power-law wall mass flux (PMF) as boundary conditions. The study reveals that the concentration over a shrinking sheet is signiRcantly different from that of a stretching surface. It s found that te solute boundary layer thickness is enhanced with the increasing values of the Schmidt number and the power-law index parameter, but decreases with enhanced vaJues of magnetic and reaction rate parameters for the PSC case. For the PMF case, the solute boundary layer thickness decreases with the increase of the Schmidt number, magnetic and reaction rate parameter for power-law index parameter n = 0. Negative solute boundary layer thickness is observed for the PMF case when n = 1 and 2, and these facts may not be realized in real-world applications.%An analytical study of the distribution of a reactant solute undergoing a first-order chemical reaction in the boundary layer flow of an electrically conducting incompressible fluid over a linearly shrinking surface is presented.The flow is permeated by an externally applied magnetic field normal to the plane of the flow.The equations governing the flow and concentration field are reduced into a set of nonlinear ordinary differential equations using similarity variables.Closed form exact solutions of the reduced concentration equation are obtained for both prescribed power-law surface concentration (PSC) and power-law wall
USTIFICATION OF A TWO-DIMENSIONAL NONLINEAR SHELL MODEL OF KOITER'S TYPE
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A two-dimensional nonlinear shell model"of Koiter's type"has recently been proposed by the first author. It is shown here that, according to two mutually exclusive sets of assumptions bearing on the associated manifold of admissible inextensional displacements, the leading term of a formal asymptotic expansion of the solution of this two-dimensional model, with the thickness as the"small" parameter, satisfies either the two-dimensional equations of a nonlinearly elastic "membrane" shell or those of a nonlinearly elastic "flexural" shell. These conclusions being identical to those recently drawn by B. Miara, then by V. Lods and B. Miara, for the leading term of a formal asymptotic expansion of the solution of the equations of three-dimensional nonlinear elasticity, again with the thickness as the "small" parameter, the nonlinear shell model of Koiter's type considered here is thus justified, at least formally.
Energy Technology Data Exchange (ETDEWEB)
Quinonez-Varela, G.; Lorenzo-Sotelo, P.; Alonso-Sadaba, O.; Arlaban-Gabeiras, M.T.; Solano-Lopez, L.; Giraut-Ruso, E.; Chocarro-Aguirrebengoa, I.; Duddy, P.; Ruiz-Guillen, J.; Rebollo-Rico, I. [Acciona Energia, S.A., Sarriguren (Spain)
2010-07-01
Voltage and reactive power control is a requirement imposed on wind power plants by numerous System Operators around the world in recent years. Nowadays, more stringent demands are being enforced to allow a larger and safer grid integration of wind generation. The Grid Codes defining these requirements differ from each other depending on the country, characteristics of the grid and other site specific conditions. This paper presents three relevant examples of Acciona's experience in adopting solutions to meet the latest voltage and reactive control requirements in Canada, Australia and Spain, each case based on different wind turbine technology namely Full Converter, DFIG and Squirrel Cage respectively. A thorough discussion of the solutions is provided including a description of the control algorithms and results from field tests performed to demonstrate compliance. (orig.)
Simple Two-Dimensional Corrections for One-Dimensional Pulse Tube Models
Lee, J. M.; Kittel, P.; Timmerhaus, K. D.; Radebaugh, R.
2004-01-01
One-dimensional oscillating flow models are very useful for designing pulse tubes. They are simple to use, not computationally intensive, and the physical relationship between temperature, pressure and mass flow are easy to understand when used in conjunction with phasor diagrams. They do not possess, however, the ability to directly calculate thermal and momentum diffusion in the direction transverse to the oscillating flow. To account for transverse effects, lumped parameter corrections, which are obtained though experiment, must be used. Or two-dimensional solutions of the differential fluid equations must be obtained. A linear two-dimensional solution to the fluid equations has been obtained. The solution provides lumped parameter corrections for one-dimensional models. The model accounts for heat transfer and shear flow between the gas and the tube. The complex Nusselt number and complex shear wall are useful in describing these corrections, with phase relations and amplitudes scaled with the Prandtl and Valensi numbers. The calculated ratio, a, between a two-dimensional solution of the oscillating temperature and velocity and a one-dimensional solution for the same shows a scales linearly with Va for Va less than 30. In this region alpha less than 0.5, that is, the enthalpy flow calculated with a two-dimensional model is 50% of a calculation using a one-dimensional model. For Va greater than 250, alpha = 0.8, showing that diffusion is still important even when it is confined to a thing layer near the tube wall.
On the multiplicity of solutions of the nonlinear reactive transport model
Directory of Open Access Journals (Sweden)
Elyas Shivanian
2014-06-01
Full Text Available The generalization of the nonlinear reaction–diffusion model in porous catalysts the so called one dimensional steady state reactive transport model is revisited. This model, which originates also in fluid and solute transport in soft tissues and microvessels, has been recently given analytical solution in terms of Taylor’s series for different families of reaction terms. This article considers the mentioned model without advective transport in the case of including Michaelis–Menten reaction term and shows that it is exactly solvable and furthermore, gives analytical exact solution in the implicit form for further physical interpretation. It is also revealed that the problem may admit unique or dual or even more triple solutions in some domains for the parameters of the model.
Two-dimensional collective Hamiltonian for chiral and wobbling modes
Chen, Q B; Zhao, P W; Jolos, R V; Meng, J
2016-01-01
A two-dimensional collective Hamiltonian (2DCH) on both azimuth and polar motions in triaxial nuclei is proposed to investigate the chiral and wobbling modes. In the 2DCH, the collective potential and the mass parameters are determined from three-dimensional tilted axis cranking (TAC) calculations. The broken chiral and signature symmetries in the TAC solutions are restored by the 2DCH. The validity of the 2DCH is illustrated with a triaxial rotor ($\\gamma=-30^\\circ$) coupling to one $h_{11/2}$ proton particle and one $h_{11/2}$ neutron hole. By diagonalizing the 2DCH, the angular momenta and energy spectra are obtained. These results agree with the exact solutions of the particle rotor model (PRM) at high rotational frequencies. However, at low frequencies, the energies given by the 2DCH are larger than those by the PRM due to the underestimation of the mass parameters. In addition, with increasing angular momentum, the transitions from the chiral vibration to chiral rotation and further to longitudinal wobb...
Two-dimensional collective Hamiltonian for chiral and wobbling modes
Chen, Q. B.; Zhang, S. Q.; Zhao, P. W.; Jolos, R. V.; Meng, J.
2016-10-01
A two-dimensional collective Hamiltonian (2DCH) on both azimuth and polar motions in triaxial nuclei is proposed to investigate the chiral and wobbling modes. In the 2DCH, the collective potential and the mass parameters are determined from three-dimensional tilted axis cranking (TAC) calculations. The broken chiral and signature symmetries in the TAC solutions are restored by the 2DCH. The validity of the 2DCH is illustrated with a triaxial rotor (γ =-30∘ ) coupling to one h11 /2 proton particle and one h11 /2 neutron hole. By diagonalizing the 2DCH, the angular momenta and energy spectra are obtained. These results agree with the exact solutions of the particle rotor model (PRM) at high rotational frequencies. However, at low frequencies, the energies given by the 2DCH are larger than those by the PRM due to the underestimation of the mass parameters. In addition, with increasing angular momentum, the transitions from the chiral vibration to chiral rotation and further to longitudinal wobbling motion have been presented in the 2DCH.
The Chandrasekhar's Equation for Two-Dimensional Hypothetical White Dwarfs
De, Sanchari
2014-01-01
In this article we have extended the original work of Chandrasekhar on the structure of white dwarfs to the two-dimensional case. Although such two-dimensional stellar objects are hypothetical in nature, we strongly believe that the work presented in this article may be prescribed as Master of Science level class problem for the students in physics.
Beginning Introductory Physics with Two-Dimensional Motion
Huggins, Elisha
2009-01-01
During the session on "Introductory College Physics Textbooks" at the 2007 Summer Meeting of the AAPT, there was a brief discussion about whether introductory physics should begin with one-dimensional motion or two-dimensional motion. Here we present the case that by starting with two-dimensional motion, we are able to introduce a considerable…
Spatiotemporal surface solitons in two-dimensional photonic lattices.
Mihalache, Dumitru; Mazilu, Dumitru; Lederer, Falk; Kivshar, Yuri S
2007-11-01
We analyze spatiotemporal light localization in truncated two-dimensional photonic lattices and demonstrate the existence of two-dimensional surface light bullets localized in the lattice corners or the edges. We study the families of the spatiotemporal surface solitons and their properties such as bistability and compare them with the modes located deep inside the photonic lattice.
Explorative data analysis of two-dimensional electrophoresis gels
DEFF Research Database (Denmark)
Schultz, J.; Gottlieb, D.M.; Petersen, Marianne Kjerstine;
2004-01-01
Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening...
Mechanics of Apparent Horizon in Two Dimensional Dilaton Gravity
Cai, Rong-Gen
2016-01-01
In this article, we give a definition of apparent horizon in a two dimensional general dilaton gravity theory. With this definition, we construct the mechanics of the apparent horizon by introducing a quasi-local energy of the theory. Our discussion generalizes the apparent horizons mechanics in general spherically symmetric spactimes in four or higher dimensions to the two dimensional dilaton gravity case.
Topological aspect of disclinations in two-dimensional crystals
Institute of Scientific and Technical Information of China (English)
Qi Wei-Kai; Zhu Tao; Chen Yong; Ren Ji-Rong
2009-01-01
By using topological current theory, this paper studies the inner topological structure of disclinations during the melting of two-dimensional systems. From two-dimensional elasticity theory, it finds that there are topological currents for topological defects in homogeneous equation. The evolution of disclinations is studied, and the branch conditions for generating, annihilating, crossing, splitting and merging of disclinations are given.
Invariant Subspaces of the Two-Dimensional Nonlinear Evolution Equations
Directory of Open Access Journals (Sweden)
Chunrong Zhu
2016-11-01
Full Text Available In this paper, we develop the symmetry-related methods to study invariant subspaces of the two-dimensional nonlinear differential operators. The conditional Lie–Bäcklund symmetry and Lie point symmetry methods are used to construct invariant subspaces of two-dimensional differential operators. We first apply the multiple conditional Lie–Bäcklund symmetries to derive invariant subspaces of the two-dimensional operators. As an application, the invariant subspaces for a class of two-dimensional nonlinear quadratic operators are provided. Furthermore, the invariant subspace method in one-dimensional space combined with the Lie symmetry reduction method and the change of variables is used to obtain invariant subspaces of the two-dimensional nonlinear operators.
A Direct Calculation of Critical Exponents of Two-Dimensional Anisotropic Ising Model
Institute of Scientific and Technical Information of China (English)
XIONG Gang; WANG Xiang-Rong
2006-01-01
Using an exact solution of the one-dimensional quantum transverse-field Ising model, we calculate the critical exponents of the two-dimensional anisotropic classicalIsing model (IM). We verify that the exponents are the same as those of isotropic classical IM. Our approach provides an alternative means of obtaining and verifying these well-known results.
Patterning two-dimensional free-standing surfaces with mesoporous conducting polymers
Liu, Shaohua; Gordiichuk, Pavlo; Wu, Zhong-Shuai; Liu, Zhaoyang; Wei, Wei; Wagner, Manfred; Mohamed-Noriega, Nasser; Wu, Dongqing; Mai, Yiyong; Herrmann, Andreas; Müllen, Klaus; Feng, Xinliang
2015-01-01
The ability to pattern functional moieties with well-defined architectures is highly important in material science, nanotechnology and bioengineering. Although two-dimensional surfaces can serve as attractive platforms, direct patterning them in solution with regular arrays remains a major challenge
Asymptotic Behavior of the Newton-Boussinesq Equation in a Two-Dimensional Channel
Fucci, Guglielmo; Singh, Preeti
2007-01-01
We prove the existence of a global attractor for the Newton-Boussinesq equation defined in a two-dimensional channel. The asymptotic compactness of the equation is derived by the uniform estimates on the tails of solutions. We also establish the regularity of the global attractor.
Effect of anisotropic scattering on radiative heat transfer in two-dimensional rectangular media
Hao Jin Bo
2003-01-01
Effect of scattering on radiative heat transfer in two-dimensional rectangular media by the finite-volume method has been studied. Compared with the existing solutions, it shows that the result obtained by the finite-volume method is reliable. Furthermore, relative errors caused by the approximation that linear and nonlinear anisotropic scattering media is simplified to isotropic scattering media have been studied.
Two new integrable cases of two-dimensional quantum mechanics with a magnetic field
Marikhin, V. G.
2016-04-01
Two integrable cases of two-dimensional Schrödinger equation with a magnetic field are proposed. Using the polar coordinates and the symmetrical gauge, we will obtain solutions of these equations through biconfluent and confluent Heun functions. The quantization rules will be derived for both systems under consideration.
Experimental Investigation of Two-Dimensional Shock Initiation Process of Cast Composition B
Institute of Scientific and Technical Information of China (English)
黄风雷; 胡湘渝
2004-01-01
A two-streak high-speed photography measuring system is designed, which can successfully record the reactive shock front and the reaction profile within the run distance of shock initiation under two-dimensional shock initiation. The strong reaction delay time and the shape of reaction shock front are determined in the cast composition B (RDX/TNT/60/40). A low level reaction zone has been found and analyzed.
Bibi, Sameena; Qamar, Shamsul; Seidel-Morgenstern, Andreas
2015-03-13
This work is concerned with the analysis of models for linear reactive chromatography describing irreversible A→B and reversible A↔B reactions. In contrast to previously published results rectangular reactant pulses are injected into initially empty or pre-equilibrated columns assuming both Dirichlet and Danckwerts boundary conditions. The models consist of two partial differential equations, accounting for convection, longitudinal dispersion and first order chemical reactions. Due to the effect of involved mechanisms on solute transport, analytical and numerical solutions of the models could be helpful to understand, design and optimize chromatographic reactors. The Laplace transformation is applied to solve the model equations analytically for linear adsorption isotherms. Statistical temporal moments are derived from solutions in the Laplace domain. Analytical results are compared with numerical predictions generated using a high-resolution finite volume scheme for two sets of boundary conditions. Several case studies are carried out to analyze reactive liquid chromatographic processes for a wide range of mass transfer and reaction kinetics. Good agreements in the results validate the correctness of the analytical solutions and accuracy of the proposed numerical algorithm.
Two-Dimensional Electron-Spin Resonance
Freed, Jack H.
2000-03-01
The extension of the concepts of 2D-NMR to ESR posed significant technological challenges, especially for liquids. ESR relaxation times are very short, as low as 10-15 ns. for T_2's. Spectral bandwidths are 100-250 MHz for nitroxide spin labels. Adequate coverage is obtained with 3-5 ns. π/2 (9-17 GHz) microwave pulses into a small low Q resonator. Dead-times are currently 25-30 ns. Additional requirements are rapid phase shifting for phase cycling, nsec. data acquisition, and fast repetition rates (10-100 kHz). 2D-ELDOR (electron-electron double resonance), which is a 3-pulse 2D-exchange experiment, takes about 30 minutes with just 0.5 nanomole spin-probe in solution (SNR 200). 2D-ELDOR is very useful in studies of molecular dynamics and local structure in complex fluids. For such media, the slow rotational dynamics requires a theory based upon the stochastic Liouville equation which enables quantitative interpretation of 2D-ELDOR experiments. In studies of spin-probes in a liquid crystal new insights could be obtained on the dynamic structure in different phases. One obtains, in addition to ordering and reorientation rates of the probes, details of the local dynamic cage: its orienting potential and (slow) relaxation rate. 2D-ELDOR overcomes the loss of resolution resulting from microscopically ordered but macroscopically disordered complex fluids. This is illustrated by studies of the dynamic structure of lipid membrane vesicles, and the effects of adding a peptide. The short dead times enable the observation of both the bulk lipids and the more immobilized lipids that coat (or are trapped) by the (aggregates of) peptides. Also, new developments of multi-quantum (2D) FT-ESR from nitroxide spin labels interacting by dipolar interactions show considerable promise in measuring distances of ca. 15-70A in macromolecules.
On the equivalence between stochastic baker's maps and two-dimensional spin systems
Lindgren, K.
2010-05-01
We show that there is a class of stochastic bakers transformations that is equivalent to the class of equilibrium solutions of two-dimensional spin systems with finite interaction. The construction is such that the equilibrium distribution of the spin lattice is identical to the invariant measure in the corresponding bakers transformation. We illustrate the equivalence by deriving two stochastic bakers maps representing the Ising model at a temperature above and below the critical temperature, respectively. A calculation of the invariant measure and the free energy in the baker system is then shown to be in agreement with analytic results of the two-dimensional Ising model.
Single and binary adsorption of reactive dyes from aqueous solutions onto clinoptilolite.
Sismanoglu, Tuba; Kismir, Yasemin; Karakus, Selcan
2010-12-15
The adsorption of Reactive Blue 21 (RB21) and Reactive Red 195 (RR195) onto clinoptilolite type natural zeolite (ZEC) has been investigated at 298.15K. The uptake of single and binary reactive dyes from aqueous solutions has been determined by UV-vis spectroscopy. Two mono-component (RB21 and RR195) and binary component (RB21 with RR195, and RR195 with RB21), isotherms were determined. The mono-component Langmuir isotherm model was applied to experimental data and the isotherm constants were calculated for RB21 and RR195 dyes. The monolayer coverage capacities of clinoptilolite for RB21 and RR195 dyes in single solution system were found as 9.652 and 3.186 mg/g, respectively. Equilibrium adsorption for binary systems was analyzed by using the extended Langmuir models. The rate of kinetic processes of single and binary dye systems onto clinoptilolite was described by using two kinetics adsorption models. The pseudo-second-order model was the best choice among the kinetic models to describe the adsorption behaviour of single and binary dyes onto clinoptilolite.
SAR processing based on the exact two-dimensional transfer function
Chang, C. Y.; Jin, M. Y.; Curlander, J. C.
1992-01-01
The two-dimensional transfer functions of several synthetic aperture radar (SAR) focusing algorithms are derived considering the spaceborne SAR environments. The formulation includes the factors of the earth rotation and the antenna squint angles. The resultant transfer functions are explicitly expressed in terms of Doppler centroid frequency and Doppler frequency rate, which can be accurately estimated from the SAR data. Point target simulation results show that the algorithm based on the two-dimensional Fourier transformation outperforms the one-dimensional one for processing data acquired from high squint angles. The two-dimensional Fourier transformation approach appears to be a viable and simple solution for the processor design of future spaceborne SAR systems.
de Barros, F P J; Fiori, A; Boso, F; Bellin, A
2015-01-01
Spatial heterogeneity of the hydraulic properties of geological porous formations leads to erratically shaped solute clouds, thus increasing the edge area of the solute body and augmenting the dilution rate. In this study, we provide a theoretical framework to quantify dilution of a non-reactive solute within a steady state flow as affected by the spatial variability of the hydraulic conductivity. Embracing the Lagrangian concentration framework, we obtain explicit semi-analytical expressions for the dilution index as a function of the structural parameters of the random hydraulic conductivity field, under the assumptions of uniform-in-the-average flow, small injection source and weak-to-mild heterogeneity. Results show how the dilution enhancement of the solute cloud is strongly dependent on both the statistical anisotropy ratio and the heterogeneity level of the porous medium. The explicit semi-analytical solution also captures the temporal evolution of the dilution rate; for the early- and late-time limits, the proposed solution recovers previous results from the literature, while at intermediate times it reflects the increasing interplay between large-scale advection and local-scale dispersion. The performance of the theoretical framework is verified with high resolution numerical results and successfully tested against the Cape Cod field data.
Filtering and control for classes of two-dimensional systems
Wu, Ligang
2015-01-01
This book focuses on filtering, control and model-reduction problems for two-dimensional (2-D) systems with imperfect information. The time-delayed 2-D systems covered have system parameters subject to uncertain, stochastic and parameter-varying changes. After an initial introduction of 2-D systems and the ideas of linear repetitive processes, the text is divided into two parts detailing: · general theory and methods of analysis and optimal synthesis for 2-D systems; and · application of the general theory to the particular case of differential/discrete linear repetitive processes. The methods developed provide a framework for stability and performance analysis, optimal and robust controller and filter design and model approximation for the systems considered. Solutions to the design problems are couched in terms of linear matrix inequalities. For readers interested in the state of the art in linear filtering, control and model reduction, Filtering and Control for Classes of ...
Two-Dimensional Heat Transfer in a Heterogeneous Fracture Network
Gisladottir, V. R.; Roubinet, D.; Tartakovsky, D. M.
2015-12-01
Geothermal energy harvesting requires extraction and injection of geothermal fluid. Doing so in an optimal way requires a quantitative understanding of site-specific heat transfer between geothermal fluid and the ambient rock. We develop a heat transfer particle-tracking approach to model that interaction. Fracture-network models of heat transfer in fractured rock explicitly account for the presence of individual fractures, ambient rock matrix, and fracture-matrix interfaces. Computational domains of such models span the meter scale, whereas fracture apertures are on the millimeter scale. The computations needed to model these multi-scale phenomenon can be prohibitively expensive, even for methods using nonuniform meshes. Our approach appreciably decreases the computational costs. Current particle-tracking methods usually assume both infinite matrix and one-dimensional (1D) heat transfer in the matrix blocks. They rely on 1D analytical solutions for heat transfer in a single fracture, which can lead to large predictive errors. Our two-dimensional (2D) heat transfer simulation algorithm is mesh-free and takes into account both longitudinal and transversal heat conduction in the matrix. It uses a probabilistic model to transfer particle to the appropriate neighboring fracture unless it returns to the fracture of origin or remains in the matrix. We use this approach to look at the impact of a fracture-network topology (e.g. the importance of smaller scale fractures), as well as the matrix block distribution on the heat transport in heterogeneous fractured rocks.
Transparent Conductive Two-Dimensional Titanium Carbide Epitaxial Thin Films.
Halim, Joseph; Lukatskaya, Maria R; Cook, Kevin M; Lu, Jun; Smith, Cole R; Näslund, Lars-Åke; May, Steven J; Hultman, Lars; Gogotsi, Yury; Eklund, Per; Barsoum, Michel W
2014-04-08
Since the discovery of graphene, the quest for two-dimensional (2D) materials has intensified greatly. Recently, a new family of 2D transition metal carbides and carbonitrides (MXenes) was discovered that is both conducting and hydrophilic, an uncommon combination. To date MXenes have been produced as powders, flakes, and colloidal solutions. Herein, we report on the fabrication of ∼1 × 1 cm(2) Ti3C2 films by selective etching of Al, from sputter-deposited epitaxial Ti3AlC2 films, in aqueous HF or NH4HF2. Films that were about 19 nm thick, etched with NH4HF2, transmit ∼90% of the light in the visible-to-infrared range and exhibit metallic conductivity down to ∼100 K. Below 100 K, the films' resistivity increases with decreasing temperature and they exhibit negative magnetoresistance-both observations consistent with a weak localization phenomenon characteristic of many 2D defective solids. This advance opens the door for the use of MXenes in electronic, photonic, and sensing applications.
Soluble, Exfoliated Two-Dimensional Nanosheets as Excellent Aqueous Lubricants.
Zhang, Wenling; Cao, Yanlin; Tian, Pengyi; Guo, Fei; Tian, Yu; Zheng, Wen; Ji, Xuqiang; Liu, Jingquan
2016-11-30
Dispersion in water of two-dimensional (2D) nanosheets is conducive to their practical applications in fundamental science communities due to their abundance, low cost, and ecofriendliness. However, it is difficult to achieve stable aqueous 2D material suspensions because of the intrinsic hydrophobic properties of the layered materials. Here, we report an effective and economic way of producing various 2D nanosheets (h-BN, MoS2, MoSe2, WS2, and graphene) as aqueous dispersions using carbon quantum dots (CQDs) as exfoliation agents and stabilizers. The dispersion was prepared through a liquid phase exfoliation. The as-synthesized stable 2D nanosheets based dispersions were characterized by UV-vis, HRTEM, AFM, Raman, XPS, and XRD. The solutions based on CQD decorated 2D nanosheets were utilized as aqueous lubricants, which realized a friction coefficient as low as 0.02 and even achieved a superlubricity under certain working conditions. The excellent lubricating properties were attributed to the synergetic effects of the 2D nanosheets and CQDs, such as good dispersion stability and easy-sliding interlayer structure. This work thus proposes a novel strategy for the design and preparation of high-performance water based green lubricants.
Efficient computation method for two-dimensional nonlinear waves
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The theory and simulation of fully-nonlinear waves in a truncated two-dimensional wave tank in time domain are presented. A piston-type wave-maker is used to generate gravity waves into the tank field in finite water depth. A damping zone is added in front of the wave-maker which makes it become one kind of absorbing wave-maker and ensures the prescribed Neumann condition. The efficiency of nmerical tank is further enhanced by installation of a sponge layer beach (SLB) in front of downtank to absorb longer weak waves that leak through the entire wave train front. Assume potential flow, the space- periodic irrotational surface waves can be represented by mixed Euler- Lagrange particles. Solving the integral equation at each time step for new normal velocities, the instantaneous free surface is integrated following time history by use of fourth-order Runge- Kutta method. The double node technique is used to deal with geometric discontinuity at the wave- body intersections. Several precise smoothing methods have been introduced to treat surface point with high curvature. No saw-tooth like instability is observed during the total simulation.The advantage of proposed wave tank has been verified by comparing with linear theoretical solution and other nonlinear results, excellent agreement in the whole range of frequencies of interest has been obtained.
Analytical solutions for reactive transport under an infiltration-redistribution cycle.
Severino, Gerardo; Indelman, Peter
2004-05-01
Transport of reactive solute in unsaturated soils under an infiltration-redistribution cycle is investigated. The study is based on the model of vertical flow and transport in the unsaturated zone proposed by Indelman et al. [J. Contam. Hydrol. 32 (1998) 77], and generalizes it by accounting for linear nonequilibrium kinetics. An exact analytical solution is derived for an irreversible desorption reaction. The transport of solute obeying linear kinetics is modeled by assuming equilibrium during the redistribution stage. The model which accounts for nonequilibrium during the infiltration and assumes equilibrium at the redistribution stage is termed partial equilibrium infiltration-redistribution model (PEIRM). It allows to derive approximate closed form solutions for transport in one-dimensional homogeneous soils. These solutions are further applied to computing the field-scale concentration by adopting the Dagan and Bresler [Soil Sci. Soc. Am. J. 43 (1979) 461] column model. The effect of soil heterogeneity on the solute spread is investigated by modeling the hydraulic saturated conductivity as a random function of horizontal coordinates. The quality of the PEIRM is illustrated by calculating the critical values of the Damköhler number which provide the achievable accuracy in estimating the solute mass in the mobile phase. The distinguishing feature of transport during the infiltration-redistribution cycle as compared to that of infiltration only is the finite depth of solute penetration. For irreversible desorption, the maximum solute penetration W/theta(r) is determined by the amount of applied water W and the residual water content theta(r). For sorption-desorption kinetics, the maximum depth of penetration z(r)(e, infinity ) also depends on the ratio between the rate of application and the column-saturated conductivity. It is shown that z(r)(e, infinity ) is bounded between the depths W/(theta(r)+K(d)) and W/theta(r) corresponding to the maximum solute
Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway
2012-09-01
ER D C/ CH L TR -1 2 -2 0 Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway C oa st al a n d H yd ra u lic s La b or at...distribution is unlimited. ERDC/CHL TR-12-20 September 2012 Two Dimensional Hydrodynamic Analysis of the Moose Creek Floodway Stephen H. Scott, Jeremy A...A two-dimensional Adaptive Hydraulics (AdH) hydrodynamic model was developed to simulate the Moose Creek Floodway. The Floodway is located
RESEARCH ON TWO-DIMENSIONAL LDA FOR FACE RECOGNITION
Institute of Scientific and Technical Information of China (English)
Han Ke; Zhu Xiuchang
2006-01-01
The letter presents an improved two-dimensional linear discriminant analysis method for feature extraction. Compared with the current two-dimensional methods for feature extraction, the improved two-dimensional linear discriminant analysis method makes full use of not only the row and the column direction information of face images but also the discriminant information among different classes. The method is evaluated using the Nanjing University of Science and Technology (NUST) 603 face database and the Aleix Martinez and Robert Benavente (AR) face database. Experimental results show that the method in the letter is feasible and effective.
ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES
Directory of Open Access Journals (Sweden)
Nikola Stefanović
2007-06-01
Full Text Available In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic leadership style, leadership theory researchers use two dimensional matrices. The two-dimensional matrices define leadership styles on the basis of different parameters. By using these parameters, one can identify two-dimensional styles.
A two-dimensional mathematical model of percutaneous drug absorption
Directory of Open Access Journals (Sweden)
Kubota K
2004-06-01
Full Text Available Abstract Background When a drug is applied on the skin surface, the concentration of the drug accumulated in the skin and the amount of the drug eliminated into the blood vessel depend on the value of a parameter, r. The values of r depend on the amount of diffusion and the normalized skin-capillary clearence. It is defined as the ratio of the steady-state drug concentration at the skin-capillary boundary to that at the skin-surface in one-dimensional models. The present paper studies the effect of the parameter values, when the region of contact of the skin with the drug, is a line segment on the skin surface. Methods Though a simple one-dimensional model is often useful to describe percutaneous drug absorption, it may be better represented by multi-dimensional models. A two-dimensional mathematical model is developed for percutaneous absorption of a drug, which may be used when the diffusion of the drug in the direction parallel to the skin surface must be examined, as well as in the direction into the skin, examined in one-dimensional models. This model consists of a linear second-order parabolic equation with appropriate initial conditions and boundary conditions. These boundary conditions are of Dirichlet type, Neumann type or Robin type. A finite-difference method which maintains second-order accuracy in space along the boundary, is developed to solve the parabolic equation. Extrapolation in time is applied to improve the accuracy in time. Solution of the parabolic equation gives the concentration of the drug in the skin at a given time. Results Simulation of the numerical methods described is carried out with various values of the parameter r. The illustrations are given in the form of figures. Conclusion Based on the values of r, conclusions are drawn about (1 the flow rate of the drug, (2 the flux and the cumulative amount of drug eliminated into the receptor cell, (3 the steady-state value of the flux, (4 the time to reach the steady
Multi-Symplectic Splitting Method for Two-Dimensional Nonlinear Schriidinger Equation
Institute of Scientific and Technical Information of China (English)
陈亚铭; 朱华君; 宋松和
2011-01-01
Using the idea of splitting numerical methods and the multi-symplectic methods, we propose a multisymplectic splitting （MSS） method to solve the two-dimensional nonlinear Schrodinger equation （2D-NLSE） in this paper. It is further shown that the method constructed in this way preserve the global symplectieity exactly. Numerical experiments for the plane wave solution and singular solution of the 2D-NLSE show the accuracy and effectiveness of the proposed method.
Image interpolation by two-dimensional parametric cubic convolution.
Shi, Jiazheng; Reichenbach, Stephen E
2006-07-01
Cubic convolution is a popular method for image interpolation. Traditionally, the piecewise-cubic kernel has been derived in one dimension with one parameter and applied to two-dimensional (2-D) images in a separable fashion. However, images typically are statistically nonseparable, which motivates this investigation of nonseparable cubic convolution. This paper derives two new nonseparable, 2-D cubic-convolution kernels. The first kernel, with three parameters (designated 2D-3PCC), is the most general 2-D, piecewise-cubic interpolator defined on [-2, 2] x [-2, 2] with constraints for biaxial symmetry, diagonal (or 90 degrees rotational) symmetry, continuity, and smoothness. The second kernel, with five parameters (designated 2D-5PCC), relaxes the constraint of diagonal symmetry, based on the observation that many images have rotationally asymmetric statistical properties. This paper also develops a closed-form solution for determining the optimal parameter values for parametric cubic-convolution kernels with respect to ensembles of scenes characterized by autocorrelation (or power spectrum). This solution establishes a practical foundation for adaptive interpolation based on local autocorrelation estimates. Quantitative fidelity analyses and visual experiments indicate that these new methods can outperform several popular interpolation methods. An analysis of the error budgets for reconstruction error associated with blurring and aliasing illustrates that the methods improve interpolation fidelity for images with aliased components. For images with little or no aliasing, the methods yield results similar to other popular methods. Both 2D-3PCC and 2D-5PCC are low-order polynomials with small spatial support and so are easy to implement and efficient to apply.
A study of two-dimensional magnetic polaron
Institute of Scientific and Technical Information of China (English)
LIU; Tao; ZHANG; Huaihong; FENG; Mang; WANG; Kelin
2006-01-01
By using the variational method and anneal simulation, we study in this paper the self-trapped magnetic polaron (STMP) in two-dimensional anti-ferromagnetic material and the bound magnetic polaron (BMP) in ferromagnetic material. Schwinger angular momentum theory is applied to changing the problem into a coupling problem of carriers and two types of Bosons. Our calculation shows that there are single-peak and multi-peak structures in the two-dimensional STMP. For the ferromagnetic material, the properties of the two-dimensional BMP are almost the same as that in one-dimensional case; but for the anti-ferromagnetic material, the two-dimensional STMP structure is much richer than the one-dimensional case.
UPWIND DISCONTINUOUS GALERKIN METHODS FOR TWO DIMENSIONAL NEUTRON TRANSPORT EQUATIONS
Institute of Scientific and Technical Information of China (English)
袁光伟; 沈智军; 闫伟
2003-01-01
In this paper the upwind discontinuous Galerkin methods with triangle meshes for two dimensional neutron transport equations will be studied.The stability for both of the semi-discrete and full-discrete method will be proved.
Two-Dimensionally-Modulated, Magnetic Structure of Neodymium Metal
DEFF Research Database (Denmark)
Lebech, Bente; Bak, P.
1979-01-01
The incipient magnetic order of dhcp Nd is described by a two-dimensional, incommensurably modulated structure ("triple-q" structure). The ordering is accompanied by a lattice distortion that forms a similar pattern....
Entanglement Entropy for time dependent two dimensional holographic superconductor
Mazhari, N S; Myrzakulov, Kairat; Myrzakulov, R
2016-01-01
We studied entanglement entropy for a time dependent two dimensional holographic superconductor. We showed that the conserved charge of the system plays the role of the critical parameter to have condensation.
Decoherence in a Landau Quantized Two Dimensional Electron Gas
Directory of Open Access Journals (Sweden)
McGill Stephen A.
2013-03-01
Full Text Available We have studied the dynamics of a high mobility two-dimensional electron gas as a function of temperature. The presence of satellite reflections in the sample and magnet can be modeled in the time-domain.
Quantization of Two-Dimensional Gravity with Dynamical Torsion
Lavrov, P M
1999-01-01
We consider two-dimensional gravity with dynamical torsion in the Batalin - Vilkovisky and Batalin - Lavrov - Tyutin formalisms of gauge theories quantization as well as in the background field method.
Spatiotemporal dissipative solitons in two-dimensional photonic lattices.
Mihalache, Dumitru; Mazilu, Dumitru; Lederer, Falk; Kivshar, Yuri S
2008-11-01
We analyze spatiotemporal dissipative solitons in two-dimensional photonic lattices in the presence of gain and loss. In the framework of the continuous-discrete cubic-quintic Ginzburg-Landau model, we demonstrate the existence of novel classes of two-dimensional spatiotemporal dissipative lattice solitons, which also include surface solitons located in the corners or at the edges of the truncated two-dimensional photonic lattice. We find the domains of existence and stability of such spatiotemporal dissipative solitons in the relevant parameter space, for both on-site and intersite lattice solitons. We show that the on-site solitons are stable in the whole domain of their existence, whereas most of the intersite solitons are unstable. We describe the scenarios of the instability-induced dynamics of dissipative solitons in two-dimensional lattices.
Bound states of two-dimensional relativistic harmonic oscillators
Institute of Scientific and Technical Information of China (English)
Qiang Wen-Chao
2004-01-01
We give the exact normalized bound state wavefunctions and energy expressions of the Klein-Gordon and Dirac equations with equal scalar and vector harmonic oscillator potentials in the two-dimensional space.
A two-dimensional polymer prepared by organic synthesis.
Kissel, Patrick; Erni, Rolf; Schweizer, W Bernd; Rossell, Marta D; King, Benjamin T; Bauer, Thomas; Götzinger, Stephan; Schlüter, A Dieter; Sakamoto, Junji
2012-02-05
Synthetic polymers are widely used materials, as attested by a production of more than 200 millions of tons per year, and are typically composed of linear repeat units. They may also be branched or irregularly crosslinked. Here, we introduce a two-dimensional polymer with internal periodicity composed of areal repeat units. This is an extension of Staudinger's polymerization concept (to form macromolecules by covalently linking repeat units together), but in two dimensions. A well-known example of such a two-dimensional polymer is graphene, but its thermolytic synthesis precludes molecular design on demand. Here, we have rationally synthesized an ordered, non-equilibrium two-dimensional polymer far beyond molecular dimensions. The procedure includes the crystallization of a specifically designed photoreactive monomer into a layered structure, a photo-polymerization step within the crystal and a solvent-induced delamination step that isolates individual two-dimensional polymers as free-standing, monolayered molecular sheets.
Second invariant for two-dimensional classical super systems
Indian Academy of Sciences (India)
S C Mishra; Roshan Lal; Veena Mishra
2003-10-01
Construction of superpotentials for two-dimensional classical super systems (for ≥ 2) is carried out. Some interesting potentials have been studied in their super form and also their integrability.
Extreme paths in oriented two-dimensional percolation
Andjel, E. D.; Gray, L. F.
2016-01-01
International audience; A useful result about leftmost and rightmost paths in two dimensional bond percolation is proved. This result was introduced without proof in \\cite{G} in the context of the contact process in continuous time. As discussed here, it also holds for several related models, including the discrete time contact process and two dimensional site percolation. Among the consequences are a natural monotonicity in the probability of percolation between different sites and a somewha...
Two Dimensional Nucleation Process by Monte Carlo Simulation
T., Irisawa; K., Matsumoto; Y., Arima; T., Kan; Computer Center, Gakushuin University; Department of Physics, Gakushuin University
1997-01-01
Two dimensional nucleation process on substrate is investigated by Monte Carlo simulation, and the critical nucleus size and its waiting time are measured with a high accuracy. In order to measure the critical nucleus with a high accuracy, we calculate the attachment and the detachment rate to the nucleus directly, and define the critical nucleus size when both rate are equal. Using the kinematical nucleation theory by Nishioka, it is found that, our obtained kinematical two dimensional criti...
Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers
2016-06-15
polymers . 2. Introduction . Research objectives: This research aims to study the physical (van der Waals forces: crystal epitaxy and π-π...AFRL-AFOSR-JP-TR-2016-0071 Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers Cheolmin Park YONSEI UNIVERSITY...Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA2386-14-1-4054 5c. PROGRAM ELEMENT
Two-Dimensional Weak Pseudomanifolds on Eight Vertices
Indian Academy of Sciences (India)
Basudeb Datta; Nandini Nilakantan
2002-05-01
We explicitly determine all the two-dimensional weak pseudomanifolds on 8 vertices. We prove that there are (up to isomorphism) exactly 95 such weak pseudomanifolds, 44 of which are combinatorial 2-manifolds. These 95 weak pseudomanifolds triangulate 16 topological spaces. As a consequence, we prove that there are exactly three 8-vertex two-dimensional orientable pseudomanifolds which allow degree three maps to the 4-vertex 2-sphere.
Energy Technology Data Exchange (ETDEWEB)
Munakata, K.; Nakamura, A. [Faculty of Engineering and Ressource Science, Akita University, Akita-shi, Akita (Japan); Kawamura, Y. [Japan Atomic Energy Agency -JAEA, Tokai, Ibaraki (Japan)
2015-03-15
The authors have applied the isotherm equations derived from the reactive vacancy solution theory (RVST) to correlation of experimental and highly non-ideal adsorption isotherms of hydrogen and deuterium on a mordenite adsorbent, and have examined the ability of the isotherm equations to match this correlation. Several isotherm equations such as Langmuir, Freundlich, Toth, Vacancy Solution Theory and so forth were also tested, but they did not work. For the Langmuir-Freundlich equation tests have indicated that its 'ability to correlate' of the adsorption isotherms is not satisfactory. For the multi-site Langmuir-Freundlich (MSLF) equation the correlation of the isotherms appears to be somewhat improved but remains unsatisfactory. The results show that the isotherm equations derived from RVST can better correlate the experimental isotherms.
Comparison of activated carbon and bottom ash removal of reactive dye from aqueous solution
Energy Technology Data Exchange (ETDEWEB)
Dincer, A.R.; Gunes, Y.; Karakaya, N.; Gunes, E. [Trakya University, Tekirdag (Turkey). Dept. of Environmental Engineering
2007-03-15
The adsorption of reactive dye from synthetic aqueous solution onto granular activated carbon (GAC) and coal-based bottom ash (CBBA) were studied under the same experimental conditions. As an alternative to GAC CBBA was used as adsorbent for dye removal from aqueous solution. The amount of Vertigo Navy Marine (VNM) adsorbed onto CBBA was lower compared with GAC at equilibrium and dye adsorption capacity increased from 0.71 to 3.82 mg g{sup -1}, and 0.73 to 6.35 mg g{sup -1} with the initial concentration of dye from 25 to 300 mg l{sup -1} respectively. The initial dye uptake of CBBA was not so rapid as in the case of GAC and the dye uptake was slow and gradually attained equilibrium.
Two-Dimensional Materials for Sensing: Graphene and Beyond
Directory of Open Access Journals (Sweden)
Seba Sara Varghese
2015-09-01
Full Text Available Two-dimensional materials have attracted great scientific attention due to their unusual and fascinating properties for use in electronics, spintronics, photovoltaics, medicine, composites, etc. Graphene, transition metal dichalcogenides such as MoS2, phosphorene, etc., which belong to the family of two-dimensional materials, have shown great promise for gas sensing applications due to their high surface-to-volume ratio, low noise and sensitivity of electronic properties to the changes in the surroundings. Two-dimensional nanostructured semiconducting metal oxide based gas sensors have also been recognized as successful gas detection devices. This review aims to provide the latest advancements in the field of gas sensors based on various two-dimensional materials with the main focus on sensor performance metrics such as sensitivity, specificity, detection limit, response time, and reversibility. Both experimental and theoretical studies on the gas sensing properties of graphene and other two-dimensional materials beyond graphene are also discussed. The article concludes with the current challenges and future prospects for two-dimensional materials in gas sensor applications.
On the existence of two-dimensional nonlinear steady states in plane Couette flow
Rincon, Francois
2007-01-01
The problem of two-dimensional steady nonlinear dynamics in plane Couette flow is revisited using homotopy from either plane Poiseuille flow or from plane Couette flow perturbed by a small symmetry-preserving identity operator. Our results show that it is not possible to obtain the nonlinear plane Couette flow solutions reported by Cherhabili and Ehrenstein [Eur. J. Mech. B/Fluids, 14, 667 (1995)] using their Poiseuille-Couette homotopy. We also demonstrate that the steady solutions obtained by Mehta and Healey [Phys. Fluids, 17, 4108 (2005)] for small symmetry-preserving perturbations are influenced by an artefact of the modified system of equations used in their paper. However, using a modified version of their model does not help to find plane Couette flow solution in the limit of vanishing symmetry-preserving perturbations either. The issue of the existence of two-dimensional nonlinear steady states in plane Couette flow remains unsettled.
The Analysis of the Two-dimensional Diffusion Equation With a Source
Directory of Open Access Journals (Sweden)
Sunday Augustus REJU
2006-07-01
Full Text Available This study presents a new variant analysis and simulations of the two-dimensional energized wave equation remarkably different from the diffusion equations studied earlier studied. The objective functional and the dynamical energized wave are penalized to form a function called the Hamiltonian function. From this function, we obtained the necessary conditions for the optimal solutions using the maximum principle. By applying the Fourier solution to the first order differential equation, the analytical solutions for the state and control are obtained. The solutions are simulated to give visual physical interpretation of the waves and the numerical values.
A study of Reactive Red 198 adsorption on iron filings from aqueous solutions.
Azhdarpoor, Abooalfazl; Nikmanesh, Roya; Khademi, Fahime
2014-01-01
In recent years, reactive dyes have been widely used in textile industries with particular efficiency. They dyes are often toxic, carcinogenic and mutagenic. Improper treatment and non-scientific disposal of dyed wastewater from these industries into water sources has created many environmental problems and concerns around the world. The purpose of the present study is to investigate the efficiency of iron filings in adsorption of Reactive Red 198 from aqueous solutions. This study was conducted using an experimental method at the laboratory scale. In this study, the effects of operating parameters such as pH (1-11), initial dye concentration (40-400 mg/L), contact time (5-120 min) and iron dose (0.1-1 g) with a mesh ofDye concentration was determined using a spectrophotometer at a wavelength of 520 nm. The results indicated that maximum adsorption capacity of the dye in question was obtained at pH 3, contact time of 60 min and adsorbent dose of 1 g. At initial dye concentration of 100 and 200 mg/L, by increasing the dose of waste iron from 0.1 to 1 g, the removal percentage increased from approximately 76.89% to 97.28% and from 22.64% to 68.03%, respectively. At pH 3, contact time of 5 min and constant waste iron dose of 0.8 g, the dye removal efficiency was 85.34%. By increasing the contact time to 120 min, the removal efficiency increased to 99.2%. Welding iron waste as an inexpensive and available adsorbent has an optimum ability for adsorption of Reactive Red 198 from aqueous solutions.
Institute of Scientific and Technical Information of China (English)
吴万烨; 武昆; 李国英
2015-01-01
The synchronous fluorescence spectroscopy and two dimensional correlation analysis method were applied to study the aggregation behavior of acid-soluble collagen solutions (0. 2,0. 4 and 1. 6 mg·mL-1 )during the heating process of 10~70 ℃. It was found that the fluorescence excited at 292 and 282 nm (Δλ= 9 nm)belongs to the tyrosine (Tyr)residues which partici-pate in forming hydrogen bonds or not,respectively.The two dimensional correlation analysis with the temperature varying showed that with the temperature increased (10~30 ℃)hydrogen bonds among collagen molecular with Tyr residues formed in the 0. 2 mg·mL-1 collagen solution,while the higher aggregations of collagen molecular and hydrophobic micro-domains ap-peared in the 0. 4 and 1. 6 mg·mL-1 collagen solutions.With approaching the denatured temperature of collagen (36~38 ℃), the hydrophobic micro-domain and aggregates seemed to be broken in the 0. 4 and 1. 6 mg·mL-1 collagen solutions,however the hydrogen bonds in the 0. 2 mg·mL-1 were stable.Above the denaturation temperature of collagen,the triple-helix structure of collagen molecular in solution of each concentration tended to be loose.In the heating process of 45~70 ℃,this trend was more obvious.%采用恒波长同步荧光法和二维相关分析技术研究了不同浓度Ⅰ型胶原溶液中胶原分子聚集行为随温度升高（10～70℃）的变化规律。选取0．2，0．4，1．6 mg·mL－1的胶原溶液，在初始温度下各浓度溶液中胶原分子分别处于单分子状态、较低程度和较高程度的聚集态。研究表明：波长差为9 nm的同步荧光光谱中，激发波长282和292 nm处荧光峰分别归属于未参与形成氢键的 Tyr（酪氨酸）残基和参与形成氢键的Tyr残基。对升温过程同步荧光数据进行二维相关分析，得两荧光值对温度的响应顺序，进而推测得到：当温度低于30℃时，0．2 mg·mL－1溶液中出现了胶原分子间形成 Tyr 残
Institute of Scientific and Technical Information of China (English)
LIN Chang; ZHANG Xiu-Lian
2005-01-01
The nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation is analytically investigated by using the formally variable separation approach. New analytical solutions for the governing equation of this system have been obtained for dust acoustic waves in a dust plasma for the first time. We derive exact analytical expressions for the general case of the nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation.
Synthesis of two-dimensional materials by selective extraction.
Naguib, Michael; Gogotsi, Yury
2015-01-20
CONSPECTUS: Two-dimensional (2D) materials have attracted much attention in the past decade. They offer high specific surface area, as well as electronic structure and properties that differ from their bulk counterparts due to the low dimensionality. Graphene is the best known and the most studied 2D material, but metal oxides and hydroxides (including clays), dichalcogenides, boron nitride (BN), and other materials that are one or several atoms thick are receiving increasing attention. They may deliver a combination of properties that cannot be provided by other materials. The most common synthesis approach in general is by reacting different elements or compounds to form a new compound. However, this approach does not necessarily work well for low-dimensional structures, since it favors formation of energetically preferred 3D (bulk) solids. Many 2D materials are produced by exfoliation of van der Waals solids, such as graphite or MoS2, breaking large particles into 2D layers. However, these approaches are not universal; for example, 2D transition metal carbides cannot be produced by any of them. An alternative but less studied way of material synthesis is the selective extraction process, which is based on the difference in reactivity and stability between the different components (elements or structural units) of the original material. It can be achieved using thermal, chemical, or electrochemical processes. Many 2D materials have been synthesized using selective extraction, such as graphene from SiC, transition metal oxides (TMO) from layered 3D salts, and transition metal carbides or carbonitrides (MXenes) from MAX phases. Selective extraction synthesis is critically important when the bonds between the building blocks of the material are too strong (e.g., in carbides) to be broken mechanically in order to form nanostructures. Unlike extractive metallurgy, where the extracted metal is the goal of the process, selective extraction of one or more elements from
Removal of reactive dyes from aqueous solution using bagasse fly ash
Directory of Open Access Journals (Sweden)
Sumate Teachakulwiroj
2004-02-01
Full Text Available Bagasse fly ash, a waste from the sugar industry, was investigated as a replacement for the current expensive methods of removing reactive dyes (Remazol Black B; RBB, Remazol Brilliant Blue R; RBBR, and Remazol Brilliant Red F3B; RBRF3B from aqueous solutions. Bagasse fly ash was collected from a local sugar factory in Saraburi province, Thailand. It was oven dried at 110ºC overnight and sieved to the desired particle size of 150 µm or smaller. The 50 mL plastic conical tubes containing solution and bagasse fly ash were shaken at room temperature (27±2ºC. The pH values of solutions were adjusted by addition of HNO3 and NaOH. The batch study indicated that initial pH of aqueous solutions did not affect dye removal. While the removal efficiency decreased with increasing initial concentration, it increased with increasing adsorbent concentration. The best adsorptions were obtained under condition of 50 mg/L concentration, original pH solution of about 5, and 240, 300, and 240 minutes contact time for RBB, RBBR, and RBRF3B, respectively. Most adsorption experiments showed in the range of about 50% to 98% removal; that is, the efficiencies of RBB, RBBR, and RBRF3B adsorption were found to be between 58.48-98.03%, 46.15-93.47%, and 46.30- 94.60%, respectively. For the linear and nonlinear forms of the Langmuir and Freundlich models, the results indicated that the Langmuir adsorption isotherm fitted the data better than the Freundlich adsorption isotherm. Adsorption of these dyes onto bagasse fly ash was favorable sorption. Therefore, bagasse fly ash, the low-cost agricultural waste in Thailand, is suitable for use as adsorbent for RBB, RBBR, and RBRF3B under this investigation.
A new mobile-immobile model for reactive solute transport with scale-dependent dispersion
Gao, Guangyao; Zhan, Hongbin; Feng, Shaoyuan; Fu, Bojie; Ma, Ying; Huang, Guanhua
2010-08-01
This study proposed a new mobile-immobile model (MIM) to describe reactive solute transport with scale-dependent dispersion in heterogeneous porous media. The model was derived from the conventional MIM but assumed the dispersivity to be a linear or exponential function of travel distance. The linear adsorption and the first-order degradation of solute were also considered in the model. The Laplace transform technique and the de Hoog numerical Laplace inversion method were applied to solve the developed model. Solute breakthrough curves (BTCs) obtained from MIM with scale-dependent and constant dispersions were compared, and a constant effective dispersivity was provided to reflect the lumped scale-dependent dispersion effect. The effective dispersivity was calculated by arithmetically averaging the distance-dependent dispersivity. With this effective dispersivity, MIM could produce similar BTC as that from MIM with scale-dependent dispersion in porous media with moderate heterogeneity. The applicability of the proposed new model was tested with concentration data from a 1,250-cm long and highly heterogeneous soil column. The simulation results indicated that MIM with constant and linear distance-dependent dispersivities were unable to adequately describe the measured BTCs in the column, while MIM with exponential distance-dependent dispersivity satisfactorily captured the evolution of BTCs.
Two-dimensional self-organi-zation of 1-nonanethiol-capped gold nanoparticles
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl4-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammo-nium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nuclea-tion and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure.
Two-Dimensional IIR Filter Design Using Simulated Annealing Based Particle Swarm Optimization
Directory of Open Access Journals (Sweden)
Supriya Dhabal
2014-01-01
Full Text Available We present a novel hybrid algorithm based on particle swarm optimization (PSO and simulated annealing (SA for the design of two-dimensional recursive digital filters. The proposed method, known as SA-PSO, integrates the global search ability of PSO with the local search ability of SA and offsets the weakness of each other. The acceptance criterion of Metropolis is included in the basic algorithm of PSO to increase the swarm’s diversity by accepting sometimes weaker solutions also. The experimental results reveal that the performance of the optimal filter designed by the proposed SA-PSO method is improved. Further, the convergence behavior as well as optimization accuracy of proposed method has been improved significantly and computational time is also reduced. In addition, the proposed SA-PSO method also produces the best optimal solution with lower mean and variance which indicates that the algorithm can be used more efficiently in realizing two-dimensional digital filters.
Tracking dynamics of two-dimensional continuous attractor neural networks
Fung, C. C. Alan; Wong, K. Y. Michael; Wu, Si
2009-12-01
We introduce an analytically solvable model of two-dimensional continuous attractor neural networks (CANNs). The synaptic input and the neuronal response form Gaussian bumps in the absence of external stimuli, and enable the network to track external stimuli by its translational displacement in the two-dimensional space. Basis functions of the two-dimensional quantum harmonic oscillator in polar coordinates are introduced to describe the distortion modes of the Gaussian bump. The perturbative method is applied to analyze its dynamics. Testing the method by considering the network behavior when the external stimulus abruptly changes its position, we obtain results of the reaction time and the amplitudes of various distortion modes, with excellent agreement with simulation results.
Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.
Wang, Qing Hua; Kalantar-Zadeh, Kourosh; Kis, Andras; Coleman, Jonathan N; Strano, Michael S
2012-11-01
The remarkable properties of graphene have renewed interest in inorganic, two-dimensional materials with unique electronic and optical attributes. Transition metal dichalcogenides (TMDCs) are layered materials with strong in-plane bonding and weak out-of-plane interactions enabling exfoliation into two-dimensional layers of single unit cell thickness. Although TMDCs have been studied for decades, recent advances in nanoscale materials characterization and device fabrication have opened up new opportunities for two-dimensional layers of thin TMDCs in nanoelectronics and optoelectronics. TMDCs such as MoS(2), MoSe(2), WS(2) and WSe(2) have sizable bandgaps that change from indirect to direct in single layers, allowing applications such as transistors, photodetectors and electroluminescent devices. We review the historical development of TMDCs, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.
Hamiltonian formalism of two-dimensional Vlasov kinetic equation.
Pavlov, Maxim V
2014-12-08
In this paper, the two-dimensional Benney system describing long wave propagation of a finite depth fluid motion and the multi-dimensional Russo-Smereka kinetic equation describing a bubbly flow are considered. The Hamiltonian approach established by J. Gibbons for the one-dimensional Vlasov kinetic equation is extended to a multi-dimensional case. A local Hamiltonian structure associated with the hydrodynamic lattice of moments derived by D. J. Benney is constructed. A relationship between this hydrodynamic lattice of moments and the two-dimensional Vlasov kinetic equation is found. In the two-dimensional case, a Hamiltonian hydrodynamic lattice for the Russo-Smereka kinetic model is constructed. Simple hydrodynamic reductions are presented.
Control Operator for the Two-Dimensional Energized Wave Equation
Directory of Open Access Journals (Sweden)
Sunday Augustus REJU
2006-07-01
Full Text Available This paper studies the analytical model for the construction of the two-dimensional Energized wave equation. The control operator is given in term of space and time t independent variables. The integral quadratic objective cost functional is subject to the constraint of two-dimensional Energized diffusion, Heat and a source. The operator that shall be obtained extends the Conjugate Gradient method (ECGM as developed by Hestenes et al (1952, [1]. The new operator enables the computation of the penalty cost, optimal controls and state trajectories of the two-dimensional energized wave equation when apply to the Conjugate Gradient methods in (Waziri & Reju, LEJPT & LJS, Issues 9, 2006, [2-4] to appear in this series.
Two-Dimensional Electronic Spectroscopy Using Incoherent Light: Theoretical Analysis
Turner, Daniel B; Sutor, Erika J; Hendrickson, Rebecca A; Gealy, M W; Ulness, Darin J
2012-01-01
Electronic energy transfer in photosynthesis occurs over a range of time scales and under a variety of intermolecular coupling conditions. Recent work has shown that electronic coupling between chromophores can lead to coherent oscillations in two-dimensional electronic spectroscopy measurements of pigment-protein complexes measured with femtosecond laser pulses. A persistent issue in the field is to reconcile the results of measurements performed using femtosecond laser pulses with physiological illumination conditions. Noisy-light spectroscopy can begin to address this question. In this work we present the theoretical analysis of incoherent two-dimensional electronic spectroscopy, I(4) 2D ES. Simulations reveal diagonal peaks, cross peaks, and coherent oscillations similar to those observed in femtosecond two-dimensional electronic spectroscopy experiments. The results also expose fundamental differences between the femtosecond-pulse and noisy-light techniques; the differences lead to new challenges and opp...
A two-dimensional spin liquid in quantum kagome ice.
Carrasquilla, Juan; Hao, Zhihao; Melko, Roger G
2015-06-22
Actively sought since the turn of the century, two-dimensional quantum spin liquids (QSLs) are exotic phases of matter where magnetic moments remain disordered even at zero temperature. Despite ongoing searches, QSLs remain elusive, due to a lack of concrete knowledge of the microscopic mechanisms that inhibit magnetic order in materials. Here we study a model for a broad class of frustrated magnetic rare-earth pyrochlore materials called quantum spin ices. When subject to an external magnetic field along the [111] crystallographic direction, the resulting interactions contain a mix of geometric frustration and quantum fluctuations in decoupled two-dimensional kagome planes. Using quantum Monte Carlo simulations, we identify a set of interactions sufficient to promote a groundstate with no magnetic long-range order, and a gap to excitations, consistent with a Z2 spin liquid phase. This suggests an experimental procedure to search for two-dimensional QSLs within a class of pyrochlore quantum spin ice materials.
Spectral Radiative Properties of Two-Dimensional Rough Surfaces
Xuan, Yimin; Han, Yuge; Zhou, Yue
2012-12-01
Spectral radiative properties of two-dimensional rough surfaces are important for both academic research and practical applications. Besides material properties, surface structures have impact on the spectral radiative properties of rough surfaces. Based on the finite difference time domain algorithm, this paper studies the spectral energy propagation process on a two-dimensional rough surface and analyzes the effect of different factors such as the surface structure, angle, and polarization state of the incident wave on the spectral radiative properties of the two-dimensional rough surface. To quantitatively investigate the spatial distribution of energy reflected from the rough surface, the concept of the bidirectional reflectance distribution function is introduced. Correlation analysis between the reflectance and different impact factors is conducted to evaluate the influence degree. Comparison between the theoretical and experimental data is given to elucidate the accuracy of the computational code. This study is beneficial to optimizing the surface structures of optoelectronic devices such as solar cells.
Two dimensional convolute integers for machine vision and image recognition
Edwards, Thomas R.
1988-01-01
Machine vision and image recognition require sophisticated image processing prior to the application of Artificial Intelligence. Two Dimensional Convolute Integer Technology is an innovative mathematical approach for addressing machine vision and image recognition. This new technology generates a family of digital operators for addressing optical images and related two dimensional data sets. The operators are regression generated, integer valued, zero phase shifting, convoluting, frequency sensitive, two dimensional low pass, high pass and band pass filters that are mathematically equivalent to surface fitted partial derivatives. These operators are applied non-recursively either as classical convolutions (replacement point values), interstitial point generators (bandwidth broadening or resolution enhancement), or as missing value calculators (compensation for dead array element values). These operators show frequency sensitive feature selection scale invariant properties. Such tasks as boundary/edge enhancement and noise or small size pixel disturbance removal can readily be accomplished. For feature selection tight band pass operators are essential. Results from test cases are given.
Klammler, Harald; Hatfield, Kirk
2009-02-01
Permeable reactive barriers (PRBs) are a passive in situ technology that is based on the interception and physical, chemical, and/or biological remediation of a contaminant plume through installation of reactive material in an aquifer. The present work is an extension and generalization of a previous paper and derives analytical expressions for flow fields toward PRBs in two dimensions on the basis of the conformal mapping approach. Considered is the classic funnel-and-gate configuration with perpendicular funnel arms (PFGs) as well as PRBs with velocity equalization walls. While the aquifer is assumed to be homogeneous in a uniform far field, the hydraulic conductivity of the reactive material is allowed to take arbitrary values above or below the aquifer conductivity. At the up- and down-gradient interfaces between reactor and aquifer, highly permeable gravel packs are assumed to establish constant head conditions. The flow fields are analyzed regarding the widths and shapes of respective capture zones as functions of PRB type and dimensions, reactor hydraulic resistance (including flow divergence and longevity), and ambient groundwater flow direction. Expressions for discharge fields are developed as needed for particle-tracking algorithms. Charts of relative capture width are given to facilitate PRB design and may be included in more comprehensive PRB design/optimization approaches. An efficient approach is presented to estimate reactor conductivity and capture flow from monitoring the hydraulic loss at the reactor. Inherent assumptions and results are validated against numerical flow field solutions and water level field data for the PFG PRB at the Moffett Federal Airfield, California.
On two-dimensional large-scale primitive equations in oceanic dynamics(Ⅱ)
Institute of Scientific and Technical Information of China (English)
HUANG Dai-wen; GUO Bo-ling
2007-01-01
The initial boundary value problem for the two-dimensional primitive equations of largescale oceanic motion in geophysics is considered sequetially.Here the depth of the ocean is positive but not always a constant.By Faedo-Galerkin method and anisotropic inequalities,the existence and uniqueness of the global weakly strong solution and global strong solution for the problem are obtained.Moreover,by studying the asymptotic behavior of solutions for the above problem,the energy is exponential decay with time is proved.
Energy Technology Data Exchange (ETDEWEB)
Srivastava, Vineet K., E-mail: vineetsriiitm@gmail.com [ISRO Telemetry, Tracking and Command Network (ISTRAC), Bangalore-560058 (India); Awasthi, Mukesh K. [Department of Mathematics, University of Petroleum and Energy Studies, Dehradun-248007 (India); Singh, Sarita [Department of Mathematics, WIT- Uttarakhand Technical University, Dehradun-248007 (India)
2013-12-15
This article describes a new implicit finite-difference method: an implicit logarithmic finite-difference method (I-LFDM), for the numerical solution of two dimensional time-dependent coupled viscous Burgers’ equation on the uniform grid points. As the Burgers’ equation is nonlinear, the proposed technique leads to a system of nonlinear systems, which is solved by Newton's iterative method at each time step. Computed solutions are compared with the analytical solutions and those already available in the literature and it is clearly shown that the results obtained using the method is precise and reliable for solving Burgers’ equation.
Directory of Open Access Journals (Sweden)
Vineet K. Srivastava
2013-12-01
Full Text Available This article describes a new implicit finite-difference method: an implicit logarithmic finite-difference method (I-LFDM, for the numerical solution of two dimensional time-dependent coupled viscous Burgers’ equation on the uniform grid points. As the Burgers’ equation is nonlinear, the proposed technique leads to a system of nonlinear systems, which is solved by Newton's iterative method at each time step. Computed solutions are compared with the analytical solutions and those already available in the literature and it is clearly shown that the results obtained using the method is precise and reliable for solving Burgers’ equation.
Impregnated silica nanoparticles for the reactive removal of sulphur mustard from solutions.
Singh, Beer; Saxena, Amit; Nigam, Anil Kumar; Ganesan, Kumaran; Pandey, Pratibha
2009-01-30
High surface area (887.3m(2)/g) silica nanoparticles were synthesized using aerogel route and thereafter, characterized by N(2)-Brunauer-Emmet-Teller (BET), SEM and TEM techniques. The data indicated the formation of nanoparticles of silica in the size range of 24-75 nm with mesoporous characteristics. Later, these were impregnated with reactive chemicals such as N-chloro compounds, oxaziridines, polyoxometalates, etc., which have already been proven to be effective against sulphur mustard (HD). Thus, developed novel mesoporous reactive sorbents were tested for their self-decontaminating feature by conducting studies on kinetics of adsorptive removal of HD from solution. Trichloroisocyanuric acid impregnated silica nanoparticles (10%, w/w)-based system was found to be the best with least half-life value (t(1/2)=2.8 min) among prepared systems to remove and detoxify HD into nontoxic degradation products. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of HD over prepared sorbents. The study also inferred that 10% loading of impregnants over high surface area and low density silica nanoparticles enhances the rate of reaction kinetics and seems to be useful in the field of heterogeneous reaction kinetics.
Plasson, Raphaël; Tsuji, Maika; Kamata, Masazumi; Asakura, Kouichi
2011-10-01
A good comprehension of the reactivity of peptides in aqueous solution is fundamental in prebiotic chemistry, namely for understanding their stability and behavior in primitive oceans. Relying on the stereoselectivity of the involved reactions, there is a huge interest in amino acid derivatives for explaining the spontaneous emergence of homochirality on primitive Earth. The corresponding kinetic and thermodynamic parameters are however still poorly known in the literature. We studied the reactivity of alanylalanine in acidic to neutral conditions as a model system. The hydrolysis into amino acids, the epimerization of the N-terminal residue, and the cyclization into diketopiperazine could be successfully identified and studied. This kinetic investigation highlighted interesting behaviors. Complex mechanisms were observed in very acidic conditions. The relative kinetic stability of the diastereoisomers of the dipeptide is highly dependent of the pH, with the possibility to dynamically destabilize the thermodynamically more stable diastereoisomers. The existence of the cyclization of dipeptides adds complexity to the system. On one hand it brings additional stereoselectivities; on the other hand fast racemization of heterochiral dipeptides is obtained.
Canonical quantization of a two-dimensional model with anomalous breaking of gauge invariance
Girotti, Horacio Oscar; Rothe, Heinz J.; Rothe, Klaus D.
1986-01-01
We investigate in detail the operator quantum dynamics of a two-dimensional model exhibiting anomalous breaking of gauge invariance. The equal-time algebra is systematically obtained by using the Dirac-bracket formalism for constrained systems. For certain values of the regularization parameter the system is shown to undergo drastic changes. For the value of the parameter corresponding to the chiral Schwinger model no operator solutions are found to exist.
Applications of FEM and BEM in two-dimensional fracture mechanics problems
Min, J. B.; Steeve, B. E.; Swanson, G. R.
1992-08-01
A comparison of the finite element method (FEM) and boundary element method (BEM) for the solution of two-dimensional plane strain problems in fracture mechanics is presented in this paper. Stress intensity factors (SIF's) were calculated using both methods for elastic plates with either a single-edge crack or an inclined-edge crack. In particular, two currently available programs, ANSYS for finite element analysis and BEASY for boundary element analysis, were used.
Group classification of steady two-dimensional boundary-layer stagnation-point flow equations
Nadjafikhah, Mehdi; Hejazi, Seyed Reza
2010-01-01
Lie symmetry group method is applied to study the boundary-layer equations for two-dimensional steady flow of an incompressible, viscous fluid near a stagnation point at a heated stretching sheet placed in a porous medium equation. The symmetry group and its optimal system are given, and group invariant solutions associated to the symmetries are obtained. Finally the structure of the Lie algebra symmetries is determined.
A Hybrid Demon Algorithm for the Two-Dimensional Orthogonal Strip Packing Problem
Directory of Open Access Journals (Sweden)
Bili Chen
2015-01-01
Full Text Available This paper develops a hybrid demon algorithm for a two-dimensional orthogonal strip packing problem. This algorithm combines a placement procedure based on an improved heuristic, local search, and demon algorithm involved in setting one parameter. The hybrid algorithm is tested on a wide set of benchmark instances taken from the literature and compared with other well-known algorithms. The computation results validate the quality of the solutions and the effectiveness of the proposed algorithm.
Modeling of the optical properties of a two-dimensional system of small conductive particles.
Kondikov, A. A.; Tonkaev, P. A.; Chaldyshev, V. V.; Vartanyan, T. A.
2016-08-01
Software was developed for quick numerical calculations and graphic display of the absorption, reflection and transmittance spectra of two-dimensional systems of small conductive particles. It allowed us to make instant comparison of calculation results and experimental data. A lattice model was used to simulate nearly distributed particles, and the coherent-potential approximation was applied to obtain a solution to the problem of interacting particles. The Delphi programming environment was used.
Design of two-dimensional recursive filters by using neural networks.
Mladenov, V M; Mastorakis, N E
2001-01-01
A new design method for two-dimensional (2-D) recursive digital filters is investigated. The design of the 2-D filter is reduced to a constrained minimization problem the solution of which is achieved by the convergence of an appropriate neural network. The method is tested on a numerical example and compared with previously published methods when applied to the same example. Advantages of the proposed method over the existing ones are discussed as well.
Solvent Exfoliation of Electronic-Grade, Two-Dimensional Black Phosphorus
Kang, Joohoon; Wood, Joshua D.; Wells, Spencer A.; Lee, Jae-Hyeok; Liu, Xiaolong; Chen, Kan-Sheng; Hersam, Mark C.
2015-01-01
Solution dispersions of two-dimensional (2D) black phosphorus (BP), often referred to as phosphorene, are achieved by solvent exfoliation. These pristine, electronic-grade BP dispersions are produced with anhydrous, organic solvents in a sealed tip ultrasonication system, which circumvents BP degradation that would otherwise occur via solvated oxygen or water. Among conventional solvents, n-methyl-pyrrolidone (NMP) is found to provide stable, highly concentrated (~0.4 mg/mL) BP dispersions. A...
A Comparative Study of Stability Testing Approaches of Two-Dimensional Recursive Digital Filters
K. R. Santhi; M.Ponnavaikko; N. Gangatharan
2008-01-01
There are many problems in science and engineering whose solution is applied in the design of Multi-Dimensional (MD) digital filters. Digital filtering finds an important position in the field of digital signal and image processing. Recently there had been a great deal of interest in the design and stability analysis of Two-Dimensional (2-D) recursive digital filters. The design techniques for stable One Dimensional (1-D) digital filters are relatively well developed; but their extension to 2...
Observation of two-dimensional Faraday waves in extremely shallow depth.
Li, Xiaochen; Yu, Zhengyue; Liao, Shijun
2015-09-01
A family of two-dimensional Faraday waves in extremely shallow depth (1 mm to 2 mm) of absolute ethanol are observed experimentally using a Hele-Shaw cell that vibrates vertically. The same phenomena are not observed by means of water, ethanol solution, and silicone oil. These Faraday waves are quite different from the traditional ones. These phenomena are helpful to deepen and enrich our understandings about Faraday waves, and besides provide a challenging problem for computational fluid dynamics.
Decoration of gold nanoparticles with cysteine in solution: reactive molecular dynamics simulations.
Monti, Susanna; Carravetta, Vincenzo; Ågren, Hans
2016-07-14
The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption.
Two-dimensional superconductors with atomic-scale thickness
Uchihashi, Takashi
2017-01-01
Recent progress in two-dimensional superconductors with atomic-scale thickness is reviewed mainly from the experimental point of view. The superconducting systems treated here involve a variety of materials and forms: elemental metal ultrathin films and atomic layers on semiconductor surfaces; interfaces and superlattices of heterostructures made of cuprates, perovskite oxides, and rare-earth metal heavy-fermion compounds; interfaces of electric-double-layer transistors; graphene and atomic sheets of transition metal dichalcogenide; iron selenide and organic conductors on oxide and metal surfaces, respectively. Unique phenomena arising from the ultimate two dimensionality of the system and the physics behind them are discussed.
TreePM Method for Two-Dimensional Cosmological Simulations
Indian Academy of Sciences (India)
Suryadeep Ray
2004-09-01
We describe the two-dimensional TreePM method in this paper. The 2d TreePM code is an accurate and efficient technique to carry out large two-dimensional N-body simulations in cosmology. This hybrid code combines the 2d Barnes and Hut Tree method and the 2d Particle–Mesh method. We describe the splitting of force between the PM and the Tree parts. We also estimate error in force for a realistic configuration. Finally, we discuss some tests of the code.
Singular analysis of two-dimensional bifurcation system
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Bifurcation properties of two-dimensional bifurcation system are studied in this paper.Universal unfolding and transition sets of the bifurcation equations are obtained.The whole parametric plane is divided into several different persistent regions according to the type of motion,and the different qualitative bifurcation diagrams in different persistent regions are given.The bifurcation properties of the two-dimensional bifurcation system are compared with its reduced one-dimensional system.It is found that the system which is reduced to one dimension has lost many bifurcation properties.
Critical Behaviour of a Two-Dimensional Random Antiferromagnet
DEFF Research Database (Denmark)
Als-Nielsen, Jens Aage; Birgeneau, R. J.; Guggenheim, H. J.
1976-01-01
A neutron scattering study of the order parameter, correlation length and staggered susceptibility of the two-dimensional random antiferromagnet Rb2Mn0.5Ni0.5F4 is reported. The system is found to exhibit a well-defined phase transition with critical exponents identical to those of the isomorphou...... pure materials K2NiF4 and K2MnF4. Thus, in these systems, which have the asymptotic critical behaviour of the two-dimensional Ising model, randomness has no measurable effect on the phase-transition behaviour....
Nonlinear excitations in two-dimensional molecular structures with impurities
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Rasmussen, Kim; Christiansen, Peter Leth
1995-01-01
We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence of the imp......We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence...... excitations. Analytical results are in good agreement with numerical simulations of the nonlinear Schrodinger equation....
Vortices in the Two-Dimensional Simple Exclusion Process
Bodineau, T.; Derrida, B.; Lebowitz, Joel L.
2008-06-01
We show that the fluctuations of the partial current in two dimensional diffusive systems are dominated by vortices leading to a different scaling from the one predicted by the hydrodynamic large deviation theory. This is supported by exact computations of the variance of partial current fluctuations for the symmetric simple exclusion process on general graphs. On a two-dimensional torus, our exact expressions are compared to the results of numerical simulations. They confirm the logarithmic dependence on the system size of the fluctuations of the partial flux. The impact of the vortices on the validity of the fluctuation relation for partial currents is also discussed in an Appendix.
Two-dimensional hazard estimation for longevity analysis
DEFF Research Database (Denmark)
Fledelius, Peter; Guillen, M.; Nielsen, J.P.
2004-01-01
the two-dimensional mortality surface. Furthermore we look at aggregated synthetic population metrics as 'population life expectancy' and 'population survival probability'. For Danish women these metrics indicate decreasing mortality with respect to chronological time. The metrics can not directly be used......We investigate developments in Danish mortality based on data from 1974-1998 working in a two-dimensional model with chronological time and age as the two dimensions. The analyses are done with non-parametric kernel hazard estimation techniques. The only assumption is that the mortality surface...... for analysis of economic implications arising from mortality changes....
Field analysis of two-dimensional focusing grating couplers
Borsboom, P.-P.; Frankena, H. J.
1995-05-01
A different technique was developed by which several two-dimensional dielectric optical gratings, consisting 100 or more corrugations, were treated in a numerical reliable approach. The numerical examples that were presented were restricted to gratings made up of sequences of waveguide sections symmetric about the x = 0 plane. The newly developed method was effectively used to investigate the field produced by a two-dimensional focusing grating coupler. Focal-region fields were determined for three symmetrical gratings with 19, 50, and 124 corrugations. For focusing grating coupler with limited length, high-frequency intensity variations were noted in the focal region.
Self-assembly of two-dimensional DNA crystals
Institute of Scientific and Technical Information of China (English)
SONG Cheng; CHEN Yaqing; WEI Shuai; YOU Xiaozeng; XIAO Shoujun
2004-01-01
Self-assembly of synthetic oligonucleotides into two-dimensional lattices presents a 'bottom-up' approach to the fabrication of devices on nanometer scale. We report the design and observation of two-dimensional crystalline forms of DNAs that are composed of twenty-one plane oligonucleotides and one phosphate-modified oligonucleotide. These synthetic sequences are designed to self-assemble into four double-crossover (DX) DNA tiles. The 'sticky ends' of these tiles that associate according to Watson-Crick's base pairing are programmed to build up specific periodic patterns upto tens of microns. The patterned crystals are visualized by the transmission electron microscopy.
Two-dimensional assignment with merged measurements using Langrangrian relaxation
Briers, Mark; Maskell, Simon; Philpott, Mark
2004-01-01
Closely spaced targets can result in merged measurements, which complicate data association. Such merged measurements violate any assumption that each measurement relates to a single target. As a result, it is not possible to use the auction algorithm in its simplest form (or other two-dimensional assignment algorithms) to solve the two-dimensional target-to-measurement assignment problem. We propose an approach that uses the auction algorithm together with Lagrangian relaxation to incorporate the additional constraints resulting from the presence of merged measurements. We conclude with some simulated results displaying the concepts introduced, and discuss the application of this research within a particle filter context.
Two-dimensional lattice Boltzmann model for magnetohydrodynamics.
Schaffenberger, Werner; Hanslmeier, Arnold
2002-10-01
We present a lattice Boltzmann model for the simulation of two-dimensional magnetohydro dynamic (MHD) flows. The model is an extension of a hydrodynamic lattice Boltzman model with 9 velocities on a square lattice resulting in a model with 17 velocities. Earlier lattice Boltzmann models for two-dimensional MHD used a bidirectional streaming rule. However, the use of such a bidirectional streaming rule is not necessary. In our model, the standard streaming rule is used, allowing smaller viscosities. To control the viscosity and the resistivity independently, a matrix collision operator is used. The model is then applied to the Hartmann flow, giving reasonable results.
Quasinormal frequencies of asymptotically flat two-dimensional black holes
Lopez-Ortega, A
2011-01-01
We discuss whether the minimally coupled massless Klein-Gordon and Dirac fields have well defined quasinormal modes in single horizon, asymptotically flat two-dimensional black holes. To get the result we solve the equations of motion in the massless limit and we also calculate the effective potentials of Schrodinger type equations. Furthermore we calculate exactly the quasinormal frequencies of the Dirac field propagating in the two-dimensional uncharged Witten black hole. We compare our results on its quasinormal frequencies with other already published.
Spin dynamics in a two-dimensional quantum gas
DEFF Research Database (Denmark)
Pedersen, Poul Lindholm; Gajdacz, Miroslav; Deuretzbacher, Frank
2014-01-01
We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions with superimp......We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions...
Decoration of gold nanoparticles with cysteine in solution: reactive molecular dynamics simulations
Monti, Susanna; Carravetta, Vincenzo; Ågren, Hans
2016-06-01
The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption.The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption. Electronic supplementary information (ESI) available: Different views of the AuNP surface coverage. Distance map describing the position of each molecule in relation to the others on the AuNP (alpha carbon distances). See DOI: 10.1039/C
Macropore system characteristics controls on non-reactive solute transport at different flow rates
Larsbo, Mats; Koestel, John
2014-05-01
Preferential flow and transport in macroporous soils are important pathways for the leaching of agrochemicals through soils. Preferential solute transport in soil is to a large extent determined by the macropore system characteristics and the water flow conditions. The importance of different characteristics of the macropore system is likely to vary with the flow conditions. The objective of this study was to determine which properties of the macropore system that control the shape of non-reactive tracer solute breakthrough curves at different steady-state flow rates. We sampled five undisturbed columns (20 cm high, 20 cm diameter) from the soil surface of four soils with clay contents between 21 and 50 %. Solute transport experiments were carried out under unsaturated conditions at 2, 4, 6, 8 and 12 mm h-1 flow rates. For each flow rate a pulse of potassium bromide solution was applied at the soil surface and the electrical conductivity was measured with high temporal resolution in the column effluent. We used the 5 % arrival time and the holdback factor to estimate the degree of preferential transport from the resulting breakthrough curves. Unsaturated hydraulic conductivities were measured at the soil surface of the columns using a tension disc infiltrometer. The macropore system was imaged by industrial X-ray computed tomography at a resolution of 125 μm in all directions. Measures of the macropore system characteristics including measures of pore continuity were calculated from these images using the ImageJ software. Results show that the degree of preferential transport is generally increasing with flow rate when larger pores become active in the transport. The degree of preferential flow was correlated to measures of macropore topology. This study show that conclusions drawn from experiments carried out at one flow rate should generally not be extrapolated to other flow rates.
Energy Technology Data Exchange (ETDEWEB)
Shumaker, D E; Woodward, C S
2005-05-03
In this paper, the authors investigate performance of a fully implicit formulation and solution method of a diffusion-reaction system modeling radiation diffusion with material energy transfer and a fusion fuel source. In certain parameter regimes this system can lead to a rapid conversion of potential energy into material energy. Accuracy in time integration is essential for a good solution since a major fraction of the fuel can be depleted in a very short time. Such systems arise in a number of application areas including evolution of a star and inertial confinement fusion. Previous work has addressed implicit solution of radiation diffusion problems. Recently Shadid and coauthors have looked at implicit and semi-implicit solution of reaction-diffusion systems. In general they have found that fully implicit is the most accurate method for difficult coupled nonlinear equations. In previous work, they have demonstrated that a method of lines approach coupled with a BDF time integrator and a Newton-Krylov nonlinear solver could efficiently and accurately solve a large-scale, implicit radiation diffusion problem. In this paper, they extend that work to include an additional heating term in the material energy equation and an equation to model the evolution of the reactive fuel density. This system now consists of three coupled equations for radiation energy, material energy, and fuel density. The radiation energy equation includes diffusion and energy exchange with material energy. The material energy equation includes reaction heating and exchange with radiation energy, and the fuel density equation includes its depletion due to the fuel consumption.
Directory of Open Access Journals (Sweden)
K. Anitha
2015-07-01
Full Text Available The adsorption of Reactive Blue 171 (Reactive Dye from aqueous solution using activated carbon prepared from Albizia amara pod shell waste as an adsorbent have been carried out. The experimental adsorption data fitted reasonably well to Langmuir and Freundlich adsorption isotherms. Kinetic parameters as a function of Initial dye concentration have been calculated and the kinetic data were substituted in Pseudo First Order, Elovich and Pseudo Second order equations. A probable explanation is offered to account for the results of kinetic study. The thermodynamic parameter enthalpy change (∆H suggests the exothermic nature of absorption of Reactive Blue 171 onto activated Albizia amara pod shell waste carbon.
Directory of Open Access Journals (Sweden)
Carlos A Bustamante Chaverra
2013-03-01
are employed to build the interpolation function. Unlike the original Kansa’s Method, the LHI is applied locally and the boundary and governing equation diﬀerential operators are used to obtain the interpolation function, giving a symmetric and non-singular collocation matrix. Analytical and Numerical Jacobian matrices are tested for the Newton-Raphson method and the derivatives of the governing equation with respect to the homotopy parameter are obtained analytically. The numerical scheme is veriﬁed by comparing the obtained results to the one-dimensional Burgers’ and two-dimensional Richards’ analytical solutions. The same results are obtained for all the non-linear solvers tested, but better convergence rates are attained with the Newton Raphson method in a double iteration scheme.
Institute of Scientific and Technical Information of China (English)
Xu Quan; Tian Qiang
2009-01-01
This paper discusses the two-dimensional discrete monatomic Fermi-Pasta-Ulam lattice, by using the method of multiple-scale and the quasi-discreteness approach. By taking into account the interaction between the atoms in the lattice and their nearest neighbours, it obtains some classes of two-dimensional local models as follows: two-dimensional bright and dark discrete soliton trains, two-dimensional bright and dark line discrete breathers, and two-dimensional bright and dark discrete breather.
Mapping two-dimensional polar active fluids to two-dimensional soap and one-dimensional sandblasting
Chen, Leiming; Lee, Chiu Fan; Toner, John
2016-07-01
Active fluids and growing interfaces are two well-studied but very different non-equilibrium systems. Each exhibits non-equilibrium behaviour distinct from that of their equilibrium counterparts. Here we demonstrate a surprising connection between these two: the ordered phase of incompressible polar active fluids in two spatial dimensions without momentum conservation, and growing one-dimensional interfaces (that is, the 1+1-dimensional Kardar-Parisi-Zhang equation), in fact belong to the same universality class. This universality class also includes two equilibrium systems: two-dimensional smectic liquid crystals, and a peculiar kind of constrained two-dimensional ferromagnet. We use these connections to show that two-dimensional incompressible flocks are robust against fluctuations, and exhibit universal long-ranged, anisotropic spatio-temporal correlations of those fluctuations. We also thereby determine the exact values of the anisotropy exponent ζ and the roughness exponents χx,y that characterize these correlations.
Waiting Time Dynamics in Two-Dimensional Infrared Spectroscopy
Jansen, Thomas L. C.; Knoester, Jasper
We review recent work on the waiting time dynamics of coherent two-dimensional infrared (2DIR) spectroscopy. This dynamics can reveal chemical and physical processes that take place on the femto- and picosecond time scale, which is faster than the time scale that may be probed by, for example,
The partition function of two-dimensional string theory
Dijkgraaf, Robbert; Moore, Gregory; Plesser, Ronen
1993-04-01
We derive a compact and explicit expression for the generating functional of all correlation functions of tachyon operators in two-dimensional string theory. This expression makes manifest relations of the c = 1 system to KP flow nd W 1 + ∞ constraints. Moreover we derive a Kontsevich-Penner integral representation of this generating functional.
The partition function of two-dimensional string theory
Energy Technology Data Exchange (ETDEWEB)
Dijkgraaf, R. (School of Natural Sciences, Inst. for Advanced Study, Princeton, NJ (United States) Dept. of Mathematics, Univ. Amsterdam (Netherlands)); Moore, G.; Plesser, R. (Dept. of Physics, Yale Univ., New Haven, CT (United States))
1993-04-12
We derive a compact and explicit expression for the generating functional of all correlation functions of tachyon operators in two-dimensional string theory. This expression makes manifest relations of the c=1 system to KP flow and W[sub 1+[infinity
Two-Dimensional Electronic Spectroscopy of a Model Dimer System
Directory of Open Access Journals (Sweden)
Prokhorenko V.I.
2013-03-01
Full Text Available Two-dimensional spectra of a dimer were measured to determine the timescale for electronic decoherence at room temperature. Anti-correlated beats in the crosspeaks were observed only during the period corresponding to the measured homogeneous lifetime.
Torque magnetometry studies of two-dimensional electron systems
Schaapman, Maaike Ruth
2004-01-01
This thesis describes a study of the magnetization two-dimensional electron gases (2DEGs). To detect the typically small magnetization, a sensitive magnetometer with optical angular detection was developed. The magnetometer uses a quadrant detector to measure the rotation of the sample. By mounting
Low-frequency scattering from two-dimensional perfect conductors
DEFF Research Database (Denmark)
Hansen, Thorkild; Yaghjian, A.D
1991-01-01
Exact expressions have been obtained for the leading terms in the low-frequency expansions of the far fields scattered from three different types of two-dimensional perfect conductors: a cylinder with finite cross section, a cylindrical bump on an infinite ground plane, and a cylindrical dent...
Two-Dimensional Mesoscale-Ordered Conducting Polymers
Liu, Shaohua; Zhang, Jian; Dong, Renhao; Gordiichuk, Pavlo; Zhang, Tao; Zhuang, Xiaodong; Mai, Yiyong; Liu, Feng; Herrmann, Andreas; Feng, Xinliang
2016-01-01
Despite the availability of numerous two-dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale-ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of assem
Piezoelectricity and Piezomagnetism: Duality in two-dimensional checkerboards
Fel, Leonid G.
2002-05-01
The duality approach in two-dimensional two-component regular checkerboards is extended to piezoelectricity and piezomagnetism. The relation between the effective piezoelectric and piezomagnetic moduli is found for a checkerboard with the p6'mm'-plane symmetry group (dichromatic triangle).
Specification of a Two-Dimensional Test Case
DEFF Research Database (Denmark)
Nielsen, Peter Vilhelm
This paper describes the geometry and other boundary conditions for a test case which can be used to test different two-dimensional CFD codes in the lEA Annex 20 work. The given supply opening is large compared with practical openings. Therefore, this geometry will reduce the need for a high number...... of grid points in the wall jet region....
Operator splitting for two-dimensional incompressible fluid equations
Holden, Helge; Karper, Trygve K
2011-01-01
We analyze splitting algorithms for a class of two-dimensional fluid equations, which includes the incompressible Navier-Stokes equations and the surface quasi-geostrophic equation. Our main result is that the Godunov and Strang splitting methods converge with the expected rates provided the initial data are sufficiently regular.
Chaotic dynamics for two-dimensional tent maps
Pumariño, Antonio; Ángel Rodríguez, José; Carles Tatjer, Joan; Vigil, Enrique
2015-02-01
For a two-dimensional extension of the classical one-dimensional family of tent maps, we prove the existence of an open set of parameters for which the respective transformation presents a strange attractor with two positive Lyapounov exponents. Moreover, periodic orbits are dense on this attractor and the attractor supports a unique ergodic invariant probability measure.
Divorticity and dihelicity in two-dimensional hydrodynamics
DEFF Research Database (Denmark)
Shivamoggi, B.K.; van Heijst, G.J.F.; Juul Rasmussen, Jens
2010-01-01
A framework is developed based on the concepts of divorticity B (≡×ω, ω being the vorticity) and dihelicity g (≡vB) for discussing the theoretical structure underlying two-dimensional (2D) hydrodynamics. This formulation leads to the global and Lagrange invariants that could impose significant...
Spin-orbit torques in two-dimensional Rashba ferromagnets
Qaiumzadeh, A.; Duine, R. A.|info:eu-repo/dai/nl/304830127; Titov, M.
2015-01-01
Magnetization dynamics in single-domain ferromagnets can be triggered by a charge current if the spin-orbit coupling is sufficiently strong. We apply functional Keldysh theory to investigate spin-orbit torques in metallic two-dimensional Rashba ferromagnets in the presence of spin-dependent
Numerical blowup in two-dimensional Boussinesq equations
Yin, Zhaohua
2009-01-01
In this paper, we perform a three-stage numerical relay to investigate the finite time singularity in the two-dimensional Boussinesq approximation equations. The initial asymmetric condition is the middle-stage output of a $2048^2$ run, the highest resolution in our study is $40960^2$, and some signals of numerical blowup are observed.
Exact two-dimensional superconformal R symmetry and c extremization.
Benini, Francesco; Bobev, Nikolay
2013-02-08
We uncover a general principle dubbed c extremization, which determines the exact R symmetry of a two-dimensional unitary superconformal field theory with N=(0,2) supersymmetry. To illustrate its utility, we study superconformal theories obtained by twisted compactifications of four-dimensional N=4 super-Yang-Mills theory on Riemann surfaces and construct their gravity duals.
Zero sound in a two-dimensional dipolar Fermi gas
Lu, Z.K.; Matveenko, S.I.; Shlyapnikov, G.V.
2013-01-01
We study zero sound in a weakly interacting two-dimensional (2D) gas of single-component fermionic dipoles (polar molecules or atoms with a large magnetic moment) tilted with respect to the plane of their translational motion. It is shown that the propagation of zero sound is provided by both mean-f
Topology optimization of two-dimensional elastic wave barriers
DEFF Research Database (Denmark)
Van Hoorickx, C.; Sigmund, Ole; Schevenels, M.
2016-01-01
Topology optimization is a method that optimally distributes material in a given design domain. In this paper, topology optimization is used to design two-dimensional wave barriers embedded in an elastic halfspace. First, harmonic vibration sources are considered, and stiffened material is insert...
Thermodynamics of Two-Dimensional Black-Holes
Nappi, Chiara R.; Pasquinucci, Andrea
1992-01-01
We explore the thermodynamics of a general class of two dimensional dilatonic black-holes. A simple prescription is given that allows us to compute the mass, entropy and thermodynamic potentials, with results in agreement with those obtained by other methods, when available.
Influence of index contrast in two dimensional photonic crystal lasers
DEFF Research Database (Denmark)
Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Christiansen, Mads Brøkner;
2010-01-01
The influence of index contrast variations for obtaining single-mode operation and low threshold in dye doped polymer two dimensional photonic crystal (PhC) lasers is investigated. We consider lasers made from Pyrromethene 597 doped Ormocore imprinted with a rectangular lattice PhC having a cavit...
Magnetic order in two-dimensional nanoparticle assemblies
Georgescu, M
2008-01-01
This thesis involves a fundamental study of two-dimensional arrays of magnetic nanoparticles using non-contact Atomic Force Microscopy, Magnetic Force Microscopy, and Atomic Force Spectroscopy. The goal is to acquire a better understanding of the interactions between magnetic nanoparticles and the
Dynamical phase transitions in the two-dimensional ANNNI model
Energy Technology Data Exchange (ETDEWEB)
Barber, M.N.; Derrida, B.
1988-06-01
We study the phase diagram of the two-dimensional anisotropic next-nearest neighbor Ising (ANNNI) model by comparing the time evolution of two distinct spin configurations submitted to the same thermal noise. We clearly se several dynamical transitions between ferromagnetic, paramagnetic, antiphase, and floating phases. These dynamical transitions seem to occur rather close to the transition lines determined previously in the literature.
Magnetic order in two-dimensional nanoparticle assemblies
Georgescu, M
2008-01-01
This thesis involves a fundamental study of two-dimensional arrays of magnetic nanoparticles using non-contact Atomic Force Microscopy, Magnetic Force Microscopy, and Atomic Force Spectroscopy. The goal is to acquire a better understanding of the interactions between magnetic nanoparticles and the r
Two-Dimensional Chirality in Three-Dimensional Chemistry.
Wintner, Claude E.
1983-01-01
The concept of two-dimensional chirality is used to enhance students' understanding of three-dimensional stereochemistry. This chirality is used as a key to teaching/understanding such concepts as enaniotropism, diastereotopism, pseudoasymmetry, retention/inversion of configuration, and stereochemical results of addition to double bonds. (JN)
Field analysis of two-dimensional focusing grating
Borsboom, P.P.; Frankena, H.J.
1995-01-01
The method that we have developed [P-P. Borsboom, Ph.D. dissertation (Delft University of Technology, Delft, The Netherlands); P-P. Borsboom and H. J. Frankena, J. Opt. Soc. Am. A 12, 1134–1141 (1995)] is successfully applied to a two-dimensional focusing grating coupler. The field in the focal regi
Torque magnetometry studies of two-dimensional electron systems
Schaapman, Maaike Ruth
2004-01-01
This thesis describes a study of the magnetization two-dimensional electron gases (2DEGs). To detect the typically small magnetization, a sensitive magnetometer with optical angular detection was developed. The magnetometer uses a quadrant detector to measure the rotation of the sample. By mounting
Two-Dimensional Mesoscale-Ordered Conducting Polymers
Liu, Shaohua; Zhang, Jian; Dong, Renhao; Gordiichuk, Pavlo; Zhang, Tao; Zhuang, Xiaodong; Mai, Yiyong; Liu, Feng; Herrmann, Andreas; Feng, Xinliang
2016-01-01
Despite the availability of numerous two-dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale-ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of
Vibrations of Thin Piezoelectric Shallow Shells: Two-Dimensional Approximation
Indian Academy of Sciences (India)
N Sabu
2003-08-01
In this paper we consider the eigenvalue problem for piezoelectric shallow shells and we show that, as the thickness of the shell goes to zero, the eigensolutions of the three-dimensional piezoelectric shells converge to the eigensolutions of a two-dimensional eigenvalue problem.
Two-dimensional effects in nonlinear Kronig-Penney models
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Christiansen, Peter Leth; Rasmussen, Kim
1997-01-01
An analysis of two-dimensional (2D) effects in the nonlinear Kronig-Penney model is presented. We establish an effective one-dimensional description of the 2D effects, resulting in a set of pseudodifferential equations. The stationary states of the 2D system and their stability is studied...
Forensic potential of comprehensive two-dimensional gas chromatography
Sampat, A.; Lopatka, M.; Sjerps, M.; Vivo-Truyols, G.; Schoenmakers, P.; van Asten, A.
2016-01-01
In this study, the application of comprehensive two-dimensional (2D) gas chromatography (GC × GC) in forensic science is reviewed. The peer-reviewed publications on the forensic use of GC × GC and 2D gas chromatography with mass spectrometric detection (GC × GC-MS) have been studied in detail, not o
Easy interpretation of optical two-dimensional correlation spectra
Lazonder, K.; Pshenichnikov, M.S.; Wiersma, D.A.
2006-01-01
We demonstrate that the value of the underlying frequency-frequency correlation function can be retrieved from a two-dimensional optical correlation spectrum through a simple relationship. The proposed method yields both intuitive clues and a quantitative measure of the dynamics of the system. The t
Two Dimensional F(R) Horava-Lifshitz Gravity
Kluson, J
2016-01-01
We study two-dimensional F(R) Horava-Lifshitz gravity from the Hamiltonian point of view. We determine constraints structure with emphasis on the careful separation of the second class constraints and global first class constraints. We determine number of physical degrees of freedom and also discuss gauge fixing of the global first class constraints.
Localization of Tight Closure in Two-Dimensional Rings
Indian Academy of Sciences (India)
Kamran Divaani-Aazar; Massoud Tousi
2005-02-01
It is shown that tight closure commutes with localization in any two-dimensional ring of prime characteristic if either is a Nagata ring or possesses a weak test element. Moreover, it is proved that tight closure commutes with localization at height one prime ideals in any ring of prime characteristic.
Cryptanalysis of the Two-Dimensional Circulation Encryption Algorithm
Directory of Open Access Journals (Sweden)
Bart Preneel
2005-07-01
Full Text Available We analyze the security of the two-dimensional circulation encryption algorithm (TDCEA, recently published by Chen et al. in this journal. We show that there are several flaws in the algorithm and describe some attacks. We also address performance issues in current cryptographic designs.
New directions in science and technology: two-dimensional crystals
Energy Technology Data Exchange (ETDEWEB)
Neto, A H Castro [Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Novoselov, K, E-mail: phycastr@nus.edu.sg, E-mail: konstantin.novoselov@manchester.ac.uk [School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)
2011-08-15
Graphene is possibly one of the largest and fastest growing fields in condensed matter research. However, graphene is only one example in a large class of two-dimensional crystals with unusual properties. In this paper we briefly review the properties of graphene and look at the exciting possibilities that lie ahead.
Boundary-value problems for two-dimensional canonical systems
Hassi, Seppo; De Snoo, H; Winkler, Henrik
2000-01-01
The two-dimensional canonical system Jy' = -lHy where the nonnegative Hamiltonian matrix function H(x) is trace-normed on (0,∞) has been studied in a function-theoretic way by L. de Branges. We show that the Hamiltonian system induces a closed symmetric relation which can be reduced to a, not necess
On the continua in two-dimensional nonadiabatic magnetohydrodynamic spectra
De Ploey, A.; Van der Linden, R. A. M.; Belien, A. J. C.
2000-01-01
The equations for the continuous subspectra of the linear magnetohydrodynamic (MHD) normal modes spectrum of two-dimensional (2D) plasmas are derived in general curvilinear coordinates, taking nonadiabatic effects in the energy equation into account. Previously published derivations of continuous sp
Dislocation climb in two-dimensional discrete dislocation dynamics
Davoudi, K.M.; Nicola, L.; Vlassak, J.J.
2012-01-01
In this paper, dislocation climb is incorporated in a two-dimensional discrete dislocation dynamics model. Calculations are carried out for polycrystalline thin films, passivated on one or both surfaces. Climb allows dislocations to escape from dislocation pile-ups and reduces the strain-hardening r
SAR Processing Based On Two-Dimensional Transfer Function
Chang, Chi-Yung; Jin, Michael Y.; Curlander, John C.
1994-01-01
Exact transfer function, ETF, is two-dimensional transfer function that constitutes basis of improved frequency-domain-convolution algorithm for processing synthetic-aperture-radar, SAR data. ETF incorporates terms that account for Doppler effect of motion of radar relative to scanned ground area and for antenna squint angle. Algorithm based on ETF outperforms others.
Sound waves in two-dimensional ducts with sinusoidal walls
Nayfeh, A. H.
1974-01-01
The method of multiple scales is used to analyze the wave propagation in two-dimensional hard-walled ducts with sinusoidal walls. For traveling waves, resonance occurs whenever the wall wavenumber is equal to the difference of the wavenumbers of any two duct acoustic modes. The results show that neither of these resonating modes could occur without strongly generating the other.
Confined two-dimensional fermions at finite density
De Francia, M; Loewe, M; Santangelo, E M; De Francia, M; Falomir, H; Loewe, M; Santangelo, E M
1995-01-01
We introduce the chemical potential in a system of two-dimensional massless fermions, confined to a finite region, by imposing twisted boundary conditions in the Euclidean time direction. We explore in this simple model the application of functional techniques which could be used in more complicated situations.
Imperfect two-dimensional topological insulator field-effect transistors
Vandenberghe, William G.; Fischetti, Massimo V.
2017-01-01
To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering. We model transistors made of two-dimensional topological insulator ribbons accounting for scattering with phonons and imperfections. In the on-state, the Fermi level lies in the bulk bandgap and the electrons travel ballistically through the topologically protected edge states even in the presence of imperfections. In the off-state the Fermi level moves into the bandgap and electrons suffer from severe back-scattering. An off-current more than two-orders below the on-current is demonstrated and a high on-current is maintained even in the presence of imperfections. At low drain-source bias, the output characteristics are like those of conventional field-effect transistors, at large drain-source bias negative differential resistance is revealed. Complementary n- and p-type devices can be made enabling high-performance and low-power electronic circuits using imperfect two-dimensional topological insulators. PMID:28106059
Bounds on the capacity of constrained two-dimensional codes
DEFF Research Database (Denmark)
Forchhammer, Søren; Justesen, Jørn
2000-01-01
Bounds on the capacity of constrained two-dimensional (2-D) codes are presented. The bounds of Calkin and Wilf apply to first-order symmetric constraints. The bounds are generalized in a weaker form to higher order and nonsymmetric constraints. Results are given for constraints specified by run...
Miniature sensor for two-dimensional magnetic field distributions
Fluitman, J.H.J.; Krabbe, H.W.
1972-01-01
Describes a simple method of production of a sensor for two-dimensional magnetic field distributions. The sensor consists of a strip of Ni-Fe(81-19), of which the magnetoresistance is utilized. Typical dimensions of the strip, placed at the edge of a glass substrate, are: length 100 mu m, width 2 or
Forensic potential of comprehensive two-dimensional gas chromatography
Sampat, A.; Lopatka, M.; Sjerps, M.; Vivo-Truyols, G.; Schoenmakers, P.; van Asten, A.
2016-01-01
In this study, the application of comprehensive two-dimensional (2D) gas chromatography (GC × GC) in forensic science is reviewed. The peer-reviewed publications on the forensic use of GC × GC and 2D gas chromatography with mass spectrometric detection (GC × GC-MS) have been studied in detail, not o
Spontaneous emission in two-dimensional photonic crystal microcavities
DEFF Research Database (Denmark)
Søndergaard, Thomas
2000-01-01
The properties of the radiation field in a two-dimensional photonic crystal with and without a microcavity introduced are investigated through the concept of the position-dependent photon density of states. The position-dependent rate of spontaneous radiative decay for a two-level atom with random...
Linkage analysis by two-dimensional DNA typing
te Meerman, G J; Mullaart, E; van der Meulen, M A; den Daas, J H; Morolli, B; Uitterlinden, A G; Vijg, J
1993-01-01
In two-dimensional (2-D) DNA typing, genomic DNA fragments are separated, first according to size by electrophoresis in a neutral polyacrylamide gel and second according to sequence by denaturing gradient gel electrophoresis, followed by hybridization analysis using micro- and minisatellite core pro
Phase conjugated Andreev backscattering in two-dimensional ballistic cavities
Morpurgo, A.F.; Holl, S.; Wees, B.J.van; Klapwijk, T.M; Borghs, G.
1997-01-01
We have experimentally investigated transport in two-dimensional ballistic cavities connected to a point contact and to two superconducting electrodes with a tunable macroscopic phase difference. The point contact resistance oscillates as a function of the phase difference in a way which reflects
Two-dimensional manifold with point-like defects
Gani, Vakhid A; Rubin, Sergei G
2014-01-01
We study a class of two-dimensional extra spaces isomorphic to the $S^2$ sphere in the framework of the multidimensional gravitation. We show that there exists a family of stationary metrics that depend on the initial (boundary) conditions. All these geometries have a singular point. We also discuss the possibility for these deformed extra spaces to be considered as dark matter candidates.
Instability of two-dimensional heterotic stringy black holes
Azreg-Ainou, M
1999-01-01
We solve the eigenvalue problem of general relativity for the case of charged black holes in two-dimensional heterotic string theory, derived by McGuigan et al. For the case of $m^{2}>q^{2}$, we find a physically acceptable time-dependent growing mode; thus the black hole is unstable. The extremal case $m^{2}=q^{2}$ is stable.
Directory of Open Access Journals (Sweden)
F. V. F. Araujo
2011-12-01
Full Text Available This work reports a study on the heterogeneous Fenton reaction using hematite powder (Fe2O3 in suspension for the discolouration of the reactive dye Drimarene Red X-6BN in aqueous solutions. The efficiency of the process was studied as a function of the experimental conditions: initial pH; H2O2 dose; and hematite powder concentration; all of which showed a strong effect on the reaction kinetics. Under the best experimental conditions: pH = 2.5; H2O2 dose = 800 mg/L; and [Hematite] = 20 g/L, it was possible to remove about 99% of the initial colour in 120 minutes in a batch reaction at 25ºC. The analysis of the kinetic results suggests that the reaction is initiated by heterogeneous generation of free radicals on the hematite surface, but as soluble iron (III and iron (II species are released into the solution during the course of the reaction, a simultaneous homogeneous Fenton reaction step propagates and contributes to the overall reaction.
THE REMOVAL OF REACTIVE RED 228 DYE FROM AQUEOUS SOLUTIONS BY CHITOSAN-MODIFIED FLAX SHIVE
Directory of Open Access Journals (Sweden)
Hao Feng,
2011-12-01
Full Text Available Flax shive (FS is a byproduct from flax fiber separation. The use of absorbent prepared from chitosan-modified flax shive (CFS has been studied for removal of reactive red dye (RR228 from aqueous solutions. CFS was characterized by the Brunauer-Emmett-Teller (BET method, Scanning Electron Microscopy (SEM, Fourier Transform Infrared spectrometry (FTIR, and X-ray photoelectron spectroscopy (XPS. A batch adsorption study was conducted under various contact time, initial concentration, solution pH, and adsorbent dosage. It was found that the BET and Langmuir surface area of CFS were 1.772 m2 g-1 and 3.057 m2 g-1, respectively. Results showed that CFS has the same pores as FS and that the –NH2 group on CFS is the main adsorption site for dye sorption. Equilibrium adsorption capacity could be reached within 480 min, and RR228 uptake was satisfactory at a pH of 2.0. The percentage removal were 100%, 100%, 90%, and 85% at pH 2.0 under dye concentrations of 10 mg/L, 20 mg/L, 30 mg/L, and 40 mg/L, respectively. The adsorption accurately fitted a pseudo-second-order kinetic model and a Langmuir isotherm model. It is proposed that CFS could be applied as a low-cost absorbent in removal of dyes from wastewater.
Bedolla-Guzman, A; Feria-Reyes, R; Gutierrez-Granados, S; Peralta-Hernández, Juan M
2017-05-01
Textile manufacturing is the one responsible for water bodies' contamination through the discharge of colored wastes. This work presents the study of reactive yellow HF (RYHF) dye degradation under two different electrochemical advanced oxidation processes (EAOP), namely anodic oxidation (AO) and electro-Fenton (EF)/boron-doped diamond (BDD) process. For the AO, 100 and 300 mg/L solutions using Pt and BDD as anodes in a 100 mL stirred tank cell were used, with a supporting electrolyte of 0.05 mol/L of Na2SO4 at pH 3 under 30 and 50 mA/cm(2) current density. The EF/BDD process was carried out in a flow reactor at 4 and 7 L/min to degrade 100, 200, and 300 mg/L RYHF solutions under 50 and 80 mA/cm(2). UV-Vis determinations were used for decolorization evaluation, while high-performance liquid chromatography (HPLC) method provided information on dye degradation rate.
Reactivity of polyfunctional alcohols towards atmospheric radicals in the aqueous solution
Hoffmann, D.; Herrmann, H.
2009-04-01
Alcohols such as ethylene glycol, propylene glycol and glycerol are widely used compounds in numerous applications. The oxidation of these compounds can influence the tropospheric oxidation budget as well as contribute significantly to the formation of low volatile organic particle constituents, such as mono- and dicarboxylic acids. Model simulations applying the multiphase chemistry mechanism CAPRAM 3.0i (Chemical Aqueous Phase Radical Mechanism) show that the aqueous phase oxidation of ethylene glycol contribute significantly to the formation of the known particle constituent oxalic acid under remote (up to 1.7%) and urban (up to 9.5%) conditions. Due to their high solubility oxidation processes of polyalcohols will take place mainly in the aqueous solution. Oxidation reactions of alcohols are triggered by reactions with atmospheric radicals such as OH, NO3 and SO4-. However, for the detailed implementation of the tropospheric degradation of alcohols in atmospheric chemistry mechanisms many kinetic data, in particular as a function of the temperature, are still needed. Therefore, the reactivity of 1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2,3-propanetriol (glycerol), 1,2-butanediol, 1,4-butanediol and 1,5-pentanediol was systematically investigated towards OH, NO3 and SO4- radicals in the aqueous solution. All kinetic measurements were done as a function of the temperature. During these experiments the temperature of the measurement solution was varied between 278 ≤ T [K] ≤ 318. Experiments were carried out using laser flash photolysis technique at a wavelength of 248 nm. Rate constants were measured directly or using competition kinetics in case of OH. The kinetic data and activation parameters obtained will be summarized and discussed with available literature data. Furthermore, the data obtained will be discussed in terms of reactivity correlations and atmospheric relevance. A more detailed implementation of
Bietti, Massimo; Lanzalunga, Osvaldo
2002-04-19
Spectral properties and reactivities of ring-methoxylated diarylmethane and diarylmethanol radical cations, generated in aqueous solution by pulse and gamma-radiolysis and by the one-electron chemical oxidant potassium 12-tungstocobalt(III)ate, have been studied. The radical cations display three bands in the UV, visible, and vis-NIR regions of the spectrum. The vis-NIR band is assigned to an intramolecular charge resonance interaction (CR) between the neutral donor and charged acceptor rings, as indicated by the observation that the relative intensity of the vis-NIR band compared to that of the UV and visible bands does not increase with increasing substrate concentration and that the position and intensity of this band is influenced by the ring-substitution pattern. In acidic solution (pH = 4), monomethoxylated diarylmethanol radical cations 1a.(+ -)1e.(+) decay by C(alpha)-H deprotonation [k = (1.7-1.9) x 10(4)s(-1)] through the intermediacy of a ketyl radical, which is further oxidized in the reaction medium to give the corresponding benzophenones, as evidenced by both time-resolved spectroscopic and product studies. With the dimethoxylated radical cation 2.(+), C(alpha)-H deprotonation is instead significantly slower (k = 6.7 x 10(2)s(-1)). In basic solution, 1a.(+)-1e.(+) undergo (-)OH-induced deprotonation from the alpha-OH group with k(OH.)approximately equal to 1.4 x 10(10)M(-1)s(-1), leading to a ketyl radical anion, which is oxidized in the reaction medium to the corresponding benzophenone.
Dynamic patterns in a two-dimensional neural field with refractoriness.
Qi, Yang; Gong, Pulin
2015-08-01
The formation of dynamic patterns such as localized propagating waves is a fascinating self-organizing phenomenon that happens in a wide range of spatially extended systems including neural systems, in which they might play important functional roles. Here we derive a type of two-dimensional neural-field model with refractoriness to study the formation mechanism of localized waves. After comparing this model with existing neural-field models, we show that it is able to generate a variety of localized patterns, including stationary bumps, localized waves rotating along a circular path, and localized waves with longer-range propagation. We construct explicit bump solutions for the two-dimensional neural field and conduct a linear stability analysis on how a stationary bump transitions to a propagating wave under different spatial eigenmode perturbations. The neural-field model is then partially solved in a comoving frame to obtain localized wave solutions, whose spatial profiles are in good agreement with those obtained from simulations. We demonstrate that when there are multiple such propagating waves, they exhibit rich propagation dynamics, including propagation along periodically oscillating and irregular trajectories; these propagation dynamics are quantitatively characterized. In addition, we show that these waves can have repulsive or merging collisions, depending on their collision angles and the refractoriness parameter. Due to its analytical tractability, the two-dimensional neural-field model provides a modeling framework for studying localized propagating waves and their interactions.
Modeling two-dimensional water flow and bromide transport in a heterogeneous lignitic mine soil
Energy Technology Data Exchange (ETDEWEB)
Buczko, U.; Gerke, H.H. [Brandenburg University of Technology, Cottbus (Germany)
2006-02-15
Water and solute fluxes in lignitic mine soils and in many other soils are often highly heterogeneous. Here, heterogeneity reflects dumping-induced inclined structures and embedded heterogeneous distributions of sediment mixtures and of lignitic fragments. Such two-scale heterogeneity effects may be analyzed through the application of two-dimensional models for calculating water and solute fluxes. The objective of this study was to gain more insight to what extent spatial heterogeneity of soil hydraulic parameters contributes to preferential flow at a lignitic mine soil. The simulations pertained to the 'Barenbrucker Hohe' site in Germany where previously water fluxes and applied tracers had been monitored with a cell lysimeter, and from where a soil block had been excavated for detailed two-dimensional characterization of the hydraulic parameters using pedotransfer functions. Based on those previous studies, scenarios with different distributions of hydraulic parameters were simulated. The results show that spatial variability of hydraulic parameters alone can hardly explain the observed flow patterns. The observed preferential flow at the site was probably caused by additional factors such as hydrophobicity, the presence of root channels, anisotropy in the hydraulic conductivity, and heterogeneous root distributions. To study the relative importance of these other factors by applying two-dimensional flow models to such sites, the experimental database must be improved. Single-continuum model approaches may be insufficient for such sites.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Guoxiang; Zheng, Zuoping; Wan, Jiamin
2004-01-28
Concentrated aqueous solutions (CAS) have unique thermodynamic and physical properties. Chemical components in CAS are incompletely dissociated, especially those containing divalent or polyvalent ions. The problem is further complicated by the interaction between CAS flow processes and the naturally heterogeneous sediments. As the CAS migrates through the porous media, the composition may be altered subject to fluid-rock interactions. To effectively model reactive transport of CAS, we must take into account ion-interaction. A combination of the Pitzer ion-interaction and the ion-association model would be an appropriate way to deal with multiple-component systems if the Pitzer' parameters and thermodynamic data of dissolved components and the related minerals are available. To quantify the complicated coupling of CAS flow and transport, as well as the involved chemical reactions in natural and engineered systems, we have substantially extended an existing reactive biogeochemical transport code, BIO-CORE{sup 2D}{copyright}, by incorporating a comprehensive Pitzer ion-interaction model. In the present paper, the model, and two test cases against measured data were briefly introduced. Finally we present an application to simulate a laboratory column experiment studying the leakage of the high alkaline waste fluid stored in Hanford (a site of the U.S. Department of Energy, located in Washington State, USA). With the Pitzer ion-interaction ionic activity model, our simulation captures measured pH evolution. The simulation indicates that all the reactions controlling the pH evolution, including cation exchanges, mineral precipitation and dissolution, are coupled.
On two-dimensional large-scale primitive equations in oceanic dynamics(Ⅰ)
Institute of Scientific and Technical Information of China (English)
HUANG Dai-wen; GUO Bo-ling
2007-01-01
The initial boundary value problem for the two-dimensional primitive equations of large scale oceanic motion in geophysics is considered.It is assumed that the depth of the ocean is a positive constant.Firstly,if the initial data are square integrable,then by Fadeo-Galerkin method,the existence of the global weak solutions for the problem is obtained.Secondly, if the initial data and their vertical derivatives axe all square integrable,then by Faedo-Galerkin method and anisotropic inequalities,the existerce and uniqueness of the giobal weakly strong solution for the above initial boundary problem axe obtained.
Nonlinear low-frequency electrostatic wave dynamics in a two-dimensional quantum plasma
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Samiran, E-mail: sran_g@yahoo.com [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009 (India); Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India)
2016-08-15
The problem of two-dimensional arbitrary amplitude low-frequency electrostatic oscillation in a quasi-neutral quantum plasma is solved exactly by elementary means. In such quantum plasmas we have treated electrons quantum mechanically and ions classically. The exact analytical solution of the nonlinear system exhibits the formation of dark and black solitons. Numerical simulation also predicts the possible periodic solution of the nonlinear system. Nonlinear analysis reveals that the system does have a bifurcation at a critical Mach number that depends on the angle of propagation of the wave. The small-amplitude limit leads to the formation of weakly nonlinear Kadomstev–Petviashvili solitons.
Casimir, J. B.; Kevorkian, S.; Vinh, T.
2005-10-01
This paper describes a procedure for building the dynamic stiffness matrix of two-dimensional elements with free edge boundary conditions. The dynamic stiffness matrix is the basis of the continuous element method. Then, the formulation is used to build a Kirchhoff rectangular plate element. Gorman's method of boundary condition decomposition and Levy's series are used to obtain the strong solution of the elementary problem. A symbolic computation software partially performs the construction of the dynamic stiffness matrix from this solution. The performances of the element are evaluated from comparisons with harmonic responses of plates obtained by the finite element method.
Signatures of chaos and non-integrability in two-dimensional gravity with dynamical boundary
Directory of Open Access Journals (Sweden)
Fitkevich Maxim
2016-01-01
Full Text Available We propose a model of two-dimensional dilaton gravity with a boundary. In the bulk our model coincides with the classically integrable CGHS model; the dynamical boundary cuts of the CGHS strong-coupling region. As a result, classical dynamics in our model reminds that in the spherically-symmetric gravity: wave packets of matter fields either reflect from the boundary or form black holes. We find large integrable sector of multisoliton solutions in this model. At the same time, we argue that the model is globally non-integrable because solutions at the verge of black hole formation display chaotic properties.
Blow-up conditions for two dimensional modified Euler-Poisson equations
Lee, Yongki
2016-09-01
The multi-dimensional Euler-Poisson system describes the dynamic behavior of many important physical flows, yet as a hyperbolic system its solution can blow-up for some initial configurations. This article strives to advance our understanding on the critical threshold phenomena through the study of a two-dimensional modified Euler-Poisson system with a modified Riesz transform where the singularity at the origin is removed. We identify upper-thresholds for finite time blow-up of solutions for the modified Euler-Poisson equations with attractive/repulsive forcing.
Institute of Scientific and Technical Information of China (English)
Guangwei Yuan; Longjun Shen
2003-01-01
In this paper we are going to discuss the difference schemes with intrinsic parallelismfor the boundary value problem of the two dimensional semilinear parabolic systems. Theunconditional stability of the general finite difference schemes with intrinsic parallelismis justified in the sense of the continuous dependence of the discrete vector solution ofthe difference schemes on the discrete data of the original problems in the discrete W2(2,1)norms. Then the uniqueness of the discrete vector solution of this difference scheme followsas the consequence of the stability.
Steady Heat Transfer through a Two-Dimensional Rectangular Straight Fin
Directory of Open Access Journals (Sweden)
Raseelo J. Moitsheki
2011-01-01
Full Text Available Exact solutions for models describing heat transfer in a two-dimensional rectangular fin are constructed. Thermal conductivity, internal energy generation function, and heat transfer coefficient are assumed to be dependent on temperature. We apply the Kirchoff transformation on the governing equation. Exact solutions satisfying the realistic boundary conditions are constructed for the resulting linear equation. Symmetry analysis is carried out to classify the internal heat generation function, and some reductions are performed. Furthermore, the effects of physical parameters such as extension factor (the purely geometric fin parameter and Biot number on temperature are analyzed. Heat flux and fin efficiency are studied.
Numerical Study of Two-Dimensional Volterra Integral Equations by RDTM and Comparison with DTM
Directory of Open Access Journals (Sweden)
Reza Abazari
2013-01-01
Full Text Available The two-dimensional Volterra integral equations are solved using more recent semianalytic method, the reduced differential transform method (the so-called RDTM, and compared with the differential transform method (DTM. The concepts of DTM and RDTM are briefly explained, and their application to the two-dimensional Volterra integral equations is studied. The results obtained by DTM and RDTM together are compared with exact solution. As an important result, it is depicted that the RDTM results are more accurate in comparison with those obtained by DTM applied to the same Volterra integral equations. The numerical results reveal that the RDTM is very effective, convenient, and quite accurate compared to the other kind of nonlinear integral equations. It is predicted that the RDTM can be found widely applicable in engineering sciences.
Short-pulsed laser transport in two-dimensional scattering media by natural element method.
Zhang, Yong; Yi, Hong-Liang; Xie, Ming; Tan, He-Ping
2014-04-01
The natural element method (NEM) is extended to solve transient radiative transfer (TRT) in two-dimensional semitransparent media subjected to a collimated short laser irradiation. The least-squares (LS) weighted residuals approach is employed to spatially discretize the transient radiative heat transfer equation. First, for the case of the refractive index matched boundary, LSNEM solutions to TRT are validated by comparison with results reported in the literature. Effects of the incident angle on time-resolved signals of transmittance and reflectance are investigated. Afterward, the accuracy of this algorithm for the case of the refractive index mismatched boundary is studied. Finally, the LSNEM is extended to study the TRT in a two-dimensional semitransparent medium with refractive index discontinuity irradiated by the short pulse laser. The effects of scattering albedo, optical thickness, scattering phase function, and refractive index on transmittance and reflectance signals are investigated. Several interesting trends on the time-resolved signals are observed and analyzed.
A Novel Machine Learning Strategy Based on Two-Dimensional Numerical Models in Financial Engineering
Directory of Open Access Journals (Sweden)
Qingzhen Xu
2013-01-01
Full Text Available Machine learning is the most commonly used technique to address larger and more complex tasks by analyzing the most relevant information already present in databases. In order to better predict the future trend of the index, this paper proposes a two-dimensional numerical model for machine learning to simulate major U.S. stock market index and uses a nonlinear implicit finite-difference method to find numerical solutions of the two-dimensional simulation model. The proposed machine learning method uses partial differential equations to predict the stock market and can be extensively used to accelerate large-scale data processing on the history database. The experimental results show that the proposed algorithm reduces the prediction error and improves forecasting precision.
On the origins of vortex shedding in two-dimensional incompressible flows
Boghosian, M. E.; Cassel, K. W.
2016-12-01
An exegesis of a novel mechanism leading to vortex splitting and subsequent shedding that is valid for two-dimensional incompressible, inviscid or viscous, and external or internal or wall-bounded flows, is detailed in this research. The mechanism, termed the vortex shedding mechanism (VSM) is simple and intuitive, requiring only two coincident conditions in the flow: (1) the existence of a location with zero momentum and (2) the presence of a net force having a positive divergence. Numerical solutions of several model problems illustrate causality of the VSM. Moreover, the VSM criteria is proved to be a necessary and sufficient condition for a vortex splitting event in any two-dimensional, incompressible flow. The VSM is shown to exist in several canonical problems including the external flow past a circular cylinder. Suppression of the von Kármán vortex street is demonstrated for Reynolds numbers of 100 and 400 by mitigating the VSM.
Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro
2016-05-12
Non-equilibrium helium atmospheric-pressure plasma (He-APP), which allows for a strong non-equilibrium chemical reaction of O2 and N2 in ambient air, uniquely produces multiple extremely reactive products, such as reactive oxygen species (ROS), in plasma-irradiated solution. We herein show that relatively short-lived unclassified reactive species (i.e., deactivated within approximately 10 min) generated by the He-APP irradiation can trigger physiologically relevant Ca(2+) influx through ruthenium red- and SKF 96365-sensitive Ca(2+)-permeable channel(s), possibly transient receptor potential channel family member(s). Our results provide novel insight into understanding of the interactions between cells and plasmas and the mechanism by which cells detect plasma-induced chemically reactive species, in addition to facilitating development of plasma applications in medicine.
Stress Wave Propagation in Two-dimensional Buckyball Lattice
Xu, Jun; Zheng, Bowen
2016-11-01
Orderly arrayed granular crystals exhibit extraordinary capability to tune stress wave propagation. Granular system of higher dimension renders many more stress wave patterns, showing its great potential for physical and engineering applications. At nanoscale, one-dimensionally arranged buckyball (C60) system has shown the ability to support solitary wave. In this paper, stress wave behaviors of two-dimensional buckyball (C60) lattice are investigated based on square close packing and hexagonal close packing. We show that the square close packed system supports highly directional Nesterenko solitary waves along initially excited chains and hexagonal close packed system tends to distribute the impulse and dissipates impact exponentially. Results of numerical calculations based on a two-dimensional nonlinear spring model are in a good agreement with the results of molecular dynamics simulations. This work enhances the understanding of wave properties and allows manipulations of nanoscale lattice and novel design of shock mitigation and nanoscale energy harvesting devices.
The separation of whale myoglobins with two-dimensional electrophoresis.
Spicer, G S
1988-10-01
Five myoglobins (sperm whale, Sei whale, Hubbs' beaked whale, pilot whale, and Amazon River dolphin) were examined using two-dimensional electrophoresis. Previous reports indicated that none of these proteins could be separated by using denaturing (in the presence of 8-9 M urea) isoelectric focusing. This result is confirmed in the present study. However, all the proteins could be separated by using denaturing nonequilibrium pH-gradient electrophoresis in the first dimension. Additionally, all the myoglobins have characteristic mobilities in the second dimension (sodium dodecyl sulfate), but these mobilities do not correspond to the molecular weights of the proteins. We conclude that two-dimensional electrophoresis can be more sensitive to differences in primary protein structure than previous studies indicate and that the assessment seems to be incorrect that this technique can separate only proteins that have a unit charge difference.
Entanglement Entropy in Two-Dimensional String Theory.
Hartnoll, Sean A; Mazenc, Edward A
2015-09-18
To understand an emergent spacetime is to understand the emergence of locality. Entanglement entropy is a powerful diagnostic of locality, because locality leads to a large amount of short distance entanglement. Two-dimensional string theory is among the very simplest instances of an emergent spatial dimension. We compute the entanglement entropy in the large-N matrix quantum mechanics dual to two-dimensional string theory in the semiclassical limit of weak string coupling. We isolate a logarithmically large, but finite, contribution that corresponds to the short distance entanglement of the tachyon field in the emergent spacetime. From the spacetime point of view, the entanglement is regulated by a nonperturbative "graininess" of space.
Topological defect motifs in two-dimensional Coulomb clusters
Radzvilavičius, A; 10.1088/0953-8984/23/38/385301
2012-01-01
The most energetically favourable arrangement of low-density electrons in an infinite two-dimensional plane is the ordered triangular Wigner lattice. However, in most instances of contemporary interest one deals instead with finite clusters of strongly interacting particles localized in potential traps, for example, in complex plasmas. In the current contribution we study distribution of topological defects in two-dimensional Coulomb clusters with parabolic lateral confinement. The minima hopping algorithm based on molecular dynamics is used to efficiently locate the ground- and low-energy metastable states, and their structure is analyzed by means of the Delaunay triangulation. The size, structure and distribution of geometry-induced lattice imperfections strongly depends on the system size and the energetic state. Besides isolated disclinations and dislocations, classification of defect motifs includes defect compounds --- grain boundaries, rosette defects, vacancies and interstitial particles. Proliferatio...
The Persistence Problem in Two-Dimensional Fluid Turbulence
Perlekar, Prasad; Mitra, Dhrubaditya; Pandit, Rahul
2010-01-01
We present a natural framework for studying the persistence problem in two-dimensional fluid turbulence by using the Okubo-Weiss parameter {\\Lambda} to distinguish between vortical and extensional regions. We then use a direct numerical simulation (DNS) of the two-dimensional, incompressible Navier-Stokes equation with Ekman friction to study probability distribution functions (PDFs) of the persistence times of vortical and extensional regions by employing both Eulerian and Lagrangian measurements. We find that, in the Eulerian case, the persistence-time PDFs have exponential tails; by contrast, this PDF for Lagrangian particles, in vortical regions, has a power-law tail with a universal exponent {\\theta} = 3.1 \\pm 0.2.
On Dirichlet eigenvectors for neutral two-dimensional Markov chains
Champagnat, Nicolas; Miclo, Laurent
2012-01-01
We consider a general class of discrete, two-dimensional Markov chains modeling the dynamics of a population with two types, without mutation or immigration, and neutral in the sense that type has no influence on each individual's birth or death parameters. We prove that all the eigenvectors of the corresponding transition matrix or infinitesimal generator \\Pi\\ can be expressed as the product of "universal" polynomials of two variables, depending on each type's size but not on the specific transitions of the dynamics, and functions depending only on the total population size. These eigenvectors appear to be Dirichlet eigenvectors for \\Pi\\ on the complement of triangular subdomains, and as a consequence the corresponding eigenvalues are ordered in a specific way. As an application, we study the quasistationary behavior of finite, nearly neutral, two-dimensional Markov chains, absorbed in the sense that 0 is an absorbing state for each component of the process.
Statistical mechanics of two-dimensional and geophysical flows
Bouchet, Freddy
2011-01-01
The theoretical study of the self-organization of two-dimensional and geophysical turbulent flows is addressed based on statistical mechanics methods. This review is a self-contained presentation of classical and recent works on this subject; from the statistical mechanics basis of the theory up to applications to Jupiter's troposphere and ocean vortices and jets. Emphasize has been placed on examples with available analytical treatment in order to favor better understanding of the physics and dynamics. The equilibrium microcanonical measure is built from the Liouville theorem. On this theoretical basis, we predict the output of the long time evolution of complex turbulent flows as statistical equilibria. This is applied to make quantitative models of two-dimensional turbulence, the Great Red Spot and other Jovian vortices, ocean jets like the Gulf-Stream, and ocean vortices. We also present recent results for non-equilibrium situations, for the studies of either the relaxation towards equilibrium or non-equi...
Two-dimensional hazard estimation for longevity analysis
DEFF Research Database (Denmark)
Fledelius, Peter; Guillen, M.; Nielsen, J.P.
2004-01-01
We investigate developments in Danish mortality based on data from 1974-1998 working in a two-dimensional model with chronological time and age as the two dimensions. The analyses are done with non-parametric kernel hazard estimation techniques. The only assumption is that the mortality surface...... the two-dimensional mortality surface. Furthermore we look at aggregated synthetic population metrics as 'population life expectancy' and 'population survival probability'. For Danish women these metrics indicate decreasing mortality with respect to chronological time. The metrics can not directly be used...... for prediction purposes. However, we suggest that life insurance companies use the estimation technique and the cross-validation for bandwidth selection when analyzing their portfolio mortality. The non-parametric approach may give valuable information prior to developing more sophisticated prediction models...
Analysis of one dimensional and two dimensional fuzzy controllers
Institute of Scientific and Technical Information of China (English)
Ban Xiaojun; Gao Xiaozhi; Huang Xianlin; Wu Tianbao
2006-01-01
The analytical structures and the corresponding mathematical properties of the one dimensional and two dimensional fuzzy controllers are first investigated in detail.The nature of these two kinds of fuzzy controllers is next probed from the perspective of control engineering. For the one dimensional fuzzy controller, it is concluded that this controller is a combination of a saturation element and a nonlinear proportional controller, and the system that employs the one dimensional fuzzy controller is the combination of an open-loop control system and a closedloop control system. For the latter case, it is concluded that it is a hybrid controller, which comprises the saturation part, zero-output part, nonlinear derivative part, nonlinear proportional part, as well as nonlinear proportional-derivative part, and the two dimensional fuzzy controller-based control system is a loop-varying system with varying number of control loops.
Extension of modified power method to two-dimensional problems
Zhang, Peng; Lee, Hyunsuk; Lee, Deokjung
2016-09-01
In this study, the generalized modified power method was extended to two-dimensional problems. A direct application of the method to two-dimensional problems was shown to be unstable when the number of requested eigenmodes is larger than a certain problem dependent number. The root cause of this instability has been identified as the degeneracy of the transfer matrix. In order to resolve this instability, the number of sub-regions for the transfer matrix was increased to be larger than the number of requested eigenmodes; and a new transfer matrix was introduced accordingly which can be calculated by the least square method. The stability of the new method has been successfully demonstrated with a neutron diffusion eigenvalue problem and the 2D C5G7 benchmark problem.
Two Dimensional Lattice Boltzmann Method for Cavity Flow Simulation
Directory of Open Access Journals (Sweden)
Panjit MUSIK
2004-01-01
Full Text Available This paper presents a simulation of incompressible viscous flow within a two-dimensional square cavity. The objective is to develop a method originated from Lattice Gas (cellular Automata (LGA, which utilises discrete lattice as well as discrete time and can be parallelised easily. Lattice Boltzmann Method (LBM, known as discrete Lattice kinetics which provide an alternative for solving the Navier–Stokes equations and are generally used for fluid simulation, is chosen for the study. A specific two-dimensional nine-velocity square Lattice model (D2Q9 Model is used in the simulation with the velocity at the top of the cavity kept fixed. LBM is an efficient method for reproducing the dynamics of cavity flow and the results which are comparable to those of previous work.
Transport behavior of water molecules through two-dimensional nanopores
Energy Technology Data Exchange (ETDEWEB)
Zhu, Chongqin; Li, Hui; Meng, Sheng, E-mail: smeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2014-11-14
Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules.
Transport behavior of water molecules through two-dimensional nanopores
Zhu, Chongqin; Li, Hui; Meng, Sheng
2014-11-01
Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules.
Thermodynamics of two-dimensional Yukawa systems across coupling regimes
Kryuchkov, Nikita P.; Khrapak, Sergey A.; Yurchenko, Stanislav O.
2017-04-01
Thermodynamics of two-dimensional Yukawa (screened Coulomb or Debye-Hückel) systems is studied systematically using molecular dynamics (MD) simulations. Simulations cover very broad parameter range spanning from weakly coupled gaseous states to strongly coupled fluid and crystalline states. Important thermodynamic quantities, such as internal energy and pressure, are obtained and accurate physically motivated fits are proposed. This allows us to put forward simple practical expressions to describe thermodynamic properties of two-dimensional Yukawa systems. For crystals, in addition to numerical simulations, the recently developed shortest-graph interpolation method is applied to describe pair correlations and hence thermodynamic properties. It is shown that the finite-temperature effects can be accounted for by using simple correction of peaks in the pair correlation function. The corresponding correction coefficients are evaluated using MD simulation. The relevance of the obtained results in the context of colloidal systems, complex (dusty) plasmas, and ions absorbed to interfaces in electrolytes is pointed out.
Topological states in two-dimensional hexagon lattice bilayers
Zhang, Ming-Ming; Xu, Lei; Zhang, Jun
2016-10-01
We investigate the topological states of the two-dimensional hexagon lattice bilayer. The system exhibits a quantum valley Hall (QVH) state when the interlayer interaction t⊥ is smaller than the nearest neighbor hopping energy t, and then translates to a trivial band insulator state when t⊥ / t > 1. Interestingly, the system is found to be a single-edge QVH state with t⊥ / t = 1. The topological phase transition also can be presented via changing bias voltage and sublattice potential in the system. The QVH states have different edge modes carrying valley current but no net charge current. The bias voltage and external electric field can be tuned easily in experiments, so the present results will provide potential application in valleytronics based on the two-dimensional hexagon lattice.
CORPORATE VALUATION USING TWO-DIMENSIONAL MONTE CARLO SIMULATION
Directory of Open Access Journals (Sweden)
Toth Reka
2010-12-01
Full Text Available In this paper, we have presented a corporate valuation model. The model combine several valuation methods in order to get more accurate results. To determine the corporate asset value we have used the Gordon-like two-stage asset valuation model based on the calculation of the free cash flow to the firm. We have used the free cash flow to the firm to determine the corporate market value, which was calculated with use of the Black-Scholes option pricing model in frame of the two-dimensional Monte Carlo simulation method. The combined model and the use of the two-dimensional simulation model provides a better opportunity for the corporate value estimation.
Two-dimensional magnetostriction under vector magnetic characteristic
Wakabayashi, D.; Enokizono, M.
2015-05-01
This paper presents two-dimensional magnetostriction of electrical steel sheet under vector magnetic characteristic. In conventional measurement method using Single Sheet Tester, the magnetic flux density, the magnetic field strength, and the magnetostriction have been measured in one direction. However, an angle between the magnetic flux density vector and the magnetic field strength vector exists because the magnetic property is vector quantity. An angle between the magnetic flux density vector and the direction of maximum magnetostriction also exists. We developed a new measurement method, which enables measurement of these angles. The vector magnetic characteristic and the two-dimensional magnetostriction have been measured using the new measurement method. The BH and Bλ curves considering the angles are shown in this paper. The analyzed results considering the angles are also made clear.
Phase separation under two-dimensional Poiseuille flow.
Kiwata, H
2001-05-01
The spinodal decomposition of a two-dimensional binary fluid under Poiseuille flow is studied by numerical simulation. We investigated time dependence of domain sizes in directions parallel and perpendicular to the flow. In an effective region of the flow, the power-law growth of a characteristic length in the direction parallel to the flow changes from the diffusive regime with the growth exponent alpha=1/3 to a new regime. The scaling invariance of the growth in the perpendicular direction is destroyed after the diffusive regime. A recurrent prevalence of thick and thin domains which determines log-time periodic oscillations has not been observed in our model. The growth exponents in the infinite system under two-dimensional Poiseuille flow are obtained by the renormalization group.
Enstrophy inertial range dynamics in generalized two-dimensional turbulence
Iwayama, Takahiro; Watanabe, Takeshi
2016-07-01
We show that the transition to a k-1 spectrum in the enstrophy inertial range of generalized two-dimensional turbulence can be derived analytically using the eddy damped quasinormal Markovianized (EDQNM) closure. The governing equation for the generalized two-dimensional fluid system includes a nonlinear term with a real parameter α . This parameter controls the relationship between the stream function and generalized vorticity and the nonlocality of the dynamics. An asymptotic analysis accounting for the overwhelming dominance of nonlocal triads allows the k-1 spectrum to be derived based upon a scaling analysis. We thereby provide a detailed analytical explanation for the scaling transition that occurs in the enstrophy inertial range at α =2 in terms of the spectral dynamics of the EDQNM closure, which extends and enhances the usual phenomenological explanations.
Explorative data analysis of two-dimensional electrophoresis gels
DEFF Research Database (Denmark)
Schultz, J.; Gottlieb, D.M.; Petersen, Marianne Kjerstine
2004-01-01
Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening...... of gels is presented. First, an approach is demonstrated in which no prior knowledge of the separated proteins is used. Alignment of the gels followed by a simple transformation of data makes it possible to analyze the gels in an automated explorative manner by principal component analysis, to determine...... if the gels should be further analyzed. A more detailed approach is done by analyzing spot volume lists by principal components analysis and partial least square regression. The use of spot volume data offers a mean to investigate the spot pattern and link the classified protein patterns to distinct spots...
Two-dimensional model of elastically coupled molecular motors
Institute of Scientific and Technical Information of China (English)
Zhang Hong-Wei; Wen Shu-Tang; Chen Gai-Rong; Li Yu-Xiao; Cao Zhong-Xing; Li Wei
2012-01-01
A flashing ratchet model of a two-headed molecular motor in a two-dimensional potential is proposed to simulate the hand-over-hand motion of kinesins.Extensive Langevin simulations of the model are performed.We discuss the dependences of motion and efficiency on the model parameters,including the external force and the temperature.A good qualitative agreement with the expected behavior is observed.
Minor magnetization loops in two-dimensional dipolar Ising model
Energy Technology Data Exchange (ETDEWEB)
Sarjala, M. [Aalto University, Department of Applied Physics, P.O. Box 14100, FI-00076 Aalto (Finland); Seppaelae, E.T., E-mail: eira.seppala@nokia.co [Nokia Research Center, Itaemerenkatu 11-13, FI-00180 Helsinki (Finland); Alava, M.J., E-mail: mikko.alava@tkk.f [Aalto University, Department of Applied Physics, P.O. Box 14100, FI-00076 Aalto (Finland)
2011-05-15
The two-dimensional dipolar Ising model is investigated for the relaxation and dynamics of minor magnetization loops. Monte Carlo simulations show that in a stripe phase an exponential decrease can be found for the magnetization maxima of the loops, M{approx}exp(-{alpha}N{sub l}) where N{sub l} is the number of loops. We discuss the limits of this behavior and its relation to the equilibrium phase diagram of the model.
Cryptography Using Multiple Two-Dimensional Chaotic Maps
Directory of Open Access Journals (Sweden)
Ibrahim S. I. Abuhaiba
2012-08-01
Full Text Available In this paper, a symmetric key block cipher cryptosystem is proposed, involving multiple two-dimensional chaotic maps and using 128-bits external secret key. Computer simulations indicate that the cipher has good diffusion and confusion properties with respect to the plaintext and the key. Moreover, it produces ciphertext with random distribution. The computation time is much less than previous related works. Theoretic analysis verifies its superiority to previous cryptosystems against different types of attacks.
A UNIVERSAL VARIATIONAL FORMULATION FOR TWO DIMENSIONAL FLUID MECHANICS
Institute of Scientific and Technical Information of China (English)
何吉欢
2001-01-01
A universal variational formulation for two dimensional fluid mechanics is obtained, which is subject to the so-called parameter-constrained equations (the relationship between parameters in two governing equations). By eliminating the constraints, the generalized variational principle (GVPs) can be readily derived from the formulation. The formulation can be applied to any conditions in case the governing equations can be converted into conservative forms. Some illustrative examples are given to testify the effectiveness and simplicity of the method.
Nonlocal bottleneck effect in two-dimensional turbulence
Biskamp, D; Schwarz, E
1998-01-01
The bottleneck pileup in the energy spectrum is investigated for several two-dimensional (2D) turbulence systems by numerical simulation using high-order diffusion terms to amplify the effect, which is weak for normal diffusion. For 2D magnetohydrodynamic (MHD) turbulence, 2D electron MHD (EMHD) turbulence and 2D thermal convection, which all exhibit direct energy cascades, a nonlocal behavior is found resulting in a logarithmic enhancement of the spectrum.
Level crossings in complex two-dimensional potentials
Indian Academy of Sciences (India)
Qing-Hai Wang
2009-08-01
Two-dimensional $\\mathcal{PT}$-symmetric quantum-mechanical systems with the complex cubic potential 12 = 2 + 2 + 2 and the complex Hénon–Heiles potential HH = 2 + 2 + (2 − 3/3) are investigated. Using numerical and perturbative methods, energy spectra are obtained to high levels. Although both potentials respect the $\\mathcal{PT}$ symmetry, the complex energy eigenvalues appear when level crossing happens between same parity eigenstates.
Extraction of plant proteins for two-dimensional electrophoresis
Granier, Fabienne
1988-01-01
Three different extraction procedures for two-dimensional electrophoresis of plant proteins are compared: (i) extraction of soluble proteins with a nondenaturing Tris-buffer, (ii) denaturing extraction in presence of sodium dodecyl sulfate at elevated temperature allowing the solubilization of membrane proteins in addition to a recovery of soluble proteins, and (iii) a trichloroacetic acid-acetone procedure allowing the direct precipitation of total proteins.
Complex dynamical invariants for two-dimensional complex potentials
Indian Academy of Sciences (India)
J S Virdi; F Chand; C N Kumar; S C Mishra
2012-08-01
Complex dynamical invariants are searched out for two-dimensional complex potentials using rationalization method within the framework of an extended complex phase space characterized by $x = x_{1} + ip_{3}. y = x_{2} + ip_{4}, p_{x} = p_{1} + ix_{3}, p_{y} = p_{2} + ix_{4}$. It is found that the cubic oscillator and shifted harmonic oscillator admit quadratic complex invariants. THe obtained invariants may be useful for studying non-Hermitian Hamiltonian systems.
Two-dimensional hydrogen negative ion in a magnetic field
Institute of Scientific and Technical Information of China (English)
Xie Wen-Fang
2004-01-01
Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of a two-dimensional hydrogen negative ion H- in a magnetic field. The results show that the ground and low-excited states of H- in low-dimensional space are more stable than those in three-dimensional space and there may exist more bound states.
А heuristic algorithm for two-dimensional strip packing problem
Dayong, Cao; Kotov, V.M.
2011-01-01
In this paper, we construct an improved best-fit heuristic algorithm for two-dimensional rectangular strip packing problem (2D-RSPP), and compare it with some heuristic and metaheuristic algorithms from literatures. The experimental results show that BFBCC could produce satisfied packing layouts than these methods, especially for the large problem of 50 items or more, BFBCC could get better results in shorter time.