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Sample records for boundary analytical solution

  1. Analytical Solutions for Beams Passing Apertures with Sharp Boundaries

    CERN Document Server

    Luz, Eitam; Malomed, Boris A

    2016-01-01

    An approximation is elaborated for the paraxial propagation of diffracted beams, with both one- and two-dimensional cross sections, which are released from apertures with sharp boundaries. The approximation applies to any beam under the condition that the thickness of its edges is much smaller than any other length scale in the beam's initial profile. The approximation can be easily generalized for any beam whose initial profile has several sharp features. Therefore, this method can be used as a tool to investigate the diffraction of beams on complex obstacles. The analytical results are compared to numerical solutions and experimental findings, which demonstrates high accuracy of the approximation. For an initially uniform field confined by sharp boundaries, this solution becomes exact for any propagation distance and any sharpness of the edges. Thus, it can be used as an efficient tool to represent the beams, produced by series of slits with a complex structure, by a simple but exact analytical solution.

  2. THE ANALYTICAL SOLUTION FOR SEDIMENT REACTION AND DIFFUSION EQUATION WITH GENERALIZED INITIAL-BOUNDARY CONDITIONS

    Institute of Scientific and Technical Information of China (English)

    熊岳山; 韦永康

    2001-01-01

    The sediment reaction and diffusion equation with generalized initial and boundary condition is studied. By using Laplace transform and Jordan lemma , an analytical solution is got, which is an extension of analytical solution provided by Cheng Kwokming James ( only diffusion was considered in analytical solution of Cheng ). Some problems arisen in the computation of analytical solution formula are also analysed.

  3. Analytical solution for 1D consolidation of unsaturated soil with mixed boundary condition

    Institute of Scientific and Technical Information of China (English)

    Zhen-dong SHAN; Dao-sheng LING; Hao-jiang DING

    2013-01-01

    Based on consolidation equations proposed for unsaturated soil,an analytical solution for 1D consolidation of an unsaturated single-layer soil with nonhomogeneous mixed boundary condition is developed.The mixed boundary condition can be used for special applications,such as tests occur in laboratory.The analytical solution is obtained by assuming all material parameters remain constant during consolidation.In the derivation of the analytical solution,the nonhomogeneous boundary condition is first transformed into a homogeneous boundary condition.Then,the eigenfunction and eigenvalue are derived according to the consolidation equations and the new boundary condition.Finally,using the method of undetermined coefficients and the orthogonal relation of the eigenfunction,the analytical solution for the new boundary condition is obtained.The present method is applicable to various types of boundary conditions.Several numerical examples are provided to investigate the consolidation behavior of an unsaturated single-layer soil with mixed boundary condition.

  4. Amendment to "Analytical Solution for the Convectively-Mixed Atmospheric Boundary Layer": Inclusion of Subsidence

    NARCIS (Netherlands)

    Ouwersloot, H.G.; Arellano, de J.V.G.

    2013-01-01

    In Ouwersloot and Vila-Guerau de Arellano (Boundary-Layer Meteorol. doi: 10. 1007/s10546-013-9816-z, 2013, this issue), the analytical solutions for the boundary-layer height and scalar evolutions are derived for the convective boundary layer, based on the prognostic equations of mixed-layer slab mo

  5. An analytical solution for the Marangoni mixed convection boundary layer flow

    DEFF Research Database (Denmark)

    Moghimi, M. A.; Kimiaeifar, Amin; Rahimpour, M.; Bagheri, G. H.

    2010-01-01

    In this article, an analytical solution for a Marangoni mixed convection boundary layer flow is presented. A similarity transform reduces the Navier-Stokes equations to a set of nonlinear ordinary differential equations, which are solved analytically by means of the homotopy analysis method (HAM...... control the convergence of the solution. The numerical solution of the similarity equations is developed and the results are in good agreement with the analytical results based on the HAM....

  6. Analytical Solution of Boundary Integral Equations for 2-D Steady Linear Wave Problems

    Institute of Scientific and Technical Information of China (English)

    J.M. Chuang

    2005-01-01

    Based on the Fourier transform, the analytical solution of boundary integral equations formulated for the complex velocity of a 2-D steady linear surface flow is derived. It has been found that before the radiation condition is imposed,free waves appear both far upstream and downstream. In order to cancel the free waves in far upstream regions, the eigensolution of a specific eigenvalue, which satisfies the homogeneous boundary integral equation, is found and superposed to the analytical solution. An example, a submerged vortex, is used to demonstrate the derived analytical solution. Furthermore,an analytical approach to imposing the radiation condition in the numerical solution of boundary integral equations for 2-D steady linear wave problems is proposed.

  7. Analytic solution of an initial-value problem from Stokes flow with free boundary

    OpenAIRE

    Xuming Xie

    2008-01-01

    We study an initial-value problem arising from Stokes flow with free boundary. If the initial data is analytic in disk $mathcal{R}_r$ containing the unit disk, it is proved that unique solution, which is analytic in $mathcal{R}_s$ for $sin (1,r)$, exists locally in time.

  8. Analytical solution of second Stokes problem of behaviour of rarefied gas with Cercignani boundary accomodation conditions

    OpenAIRE

    Latyshev, A. V.; Yushkanov, A. A.

    2012-01-01

    Analytical solution of second Stokes problem of behaviour of rarefied gas with Cercignani boundary accomodation conditions The second Stokes problem about behaviour of rarefied gas filling half-space is analytically solved. A plane, limiting half-space, makes harmonious fluctuations in the plane. The kinetic BGK-equation (Bhatnagar, Gross, Krook) is used. The boundary accomodation conditions of Cercignani of reflexion gaseous molecules from a wall are considered. Distribution function of the ...

  9. Approximate Analytical Solutions for a Class of Laminar Boundary-Layer Equations

    Institute of Scientific and Technical Information of China (English)

    Seripah Awang Kechil; Ishak Hashim; Sim Siaw Jiet

    2007-01-01

    A simple and efficient approximate analytical technique is presented to obtain solutions to a class of two-point boundary value similarity problems in fluid mechanics. This technique is based on the decomposition method which yields a general analytic solution in the form of a convergent infinite series with easily computable terms. Comparative study is carried out to show the accuracy and effectiveness of the technique.

  10. A semi-analytical solution for viscothermal wave propagation in narrow gaps with arbitrary boundary conditions.

    NARCIS (Netherlands)

    Wijnant, Ysbrand; Spiering, Ruud; Blijderveen, van Maarten; Boer, de André

    2006-01-01

    Previous research has shown that viscothermal wave propagation in narrow gaps can efficiently be described by means of the low reduced frequency model. For simple geometries and boundary conditions, analytical solutions are available. For example, Beltman [4] gives the acoustic pressure in the gap b

  11. Radionuclides migration in fractured porous rock: Analytical solutions for various boundary conditions

    International Nuclear Information System (INIS)

    Analytical solutions based on Laplace transform are developed for the problem of radionuclides transport along a discrete planar fracture in porous rock. The solutions take into account advective transport in the fracture, longitudinal hydrodynamic dispersion along the fracture axis, molecular diffusion from the fracture into the rock matrix, sorption within the rock matrix, sorption onto the surface of the fracture and radioactive decay. The initial concentration in both the fracture and the rock matrix is assumed to be zero. Four boundary conditions, constant concentration, exponentially decaying concentration, exponentially decaying flux and kinetic solubility-limited dissolution are assumed. All these analytical solutions are in a form of a single integral that is evaluated by a Gauss-Legendre quadrature for each point in space and time. A comparison between the concentration profiles with a constant concentration inlet boundary condition and those with a decaying concentration inlet boundary condition shows that the concentration profile is strongly influenced by the inlet boundary condition when the retardation factor of the matrix is high. As the dissolution rate constant approaches infinity, the inlet boundary condition of the kinetic solubility-limited dissolution model can be replaced by the boundary condition of constant concentration

  12. Analytical solution of second Stokes problem of behaviour of rarefied gas with Cercignani boundary accomodation conditions

    CERN Document Server

    Latyshev, A V

    2012-01-01

    Analytical solution of second Stokes problem of behaviour of rarefied gas with Cercignani boundary accomodation conditions The second Stokes problem about behaviour of rarefied gas filling half-space is analytically solved. A plane, limiting half-space, makes harmonious fluctuations in the plane. The kinetic BGK-equation (Bhatnagar, Gross, Krook) is used. The boundary accomodation conditions of Cercignani of reflexion gaseous molecules from a wall are considered. Distribution function of the gaseous molecules is constructed. The velocity of gas in half-space is found, also its value direct at a wall is found. The force resistance operating from gas on border is found. Besides, the capacity of dissipation of the energy falling to unit of area of the fluctuating plate limiting gas is obtained.

  13. Analytical solutions for two-dimensional soil heat flow with radiation surface boundary conditions

    International Nuclear Information System (INIS)

    Heat flow add temperature variations in soil are important in agriculture, forestry, and ecology. Nonuniform surface cover and variability in soil properties result in two-dimensional soil heat flow. This study derives analytical solutions for unsteady two-dimensional soil heat transfer problems with standard (constant temperature coefficient) and modified (temperature coefficient varies with position) radiation surface boundary conditions. Solutions are periodic in time and horizontal direction. The structure of the solutions guarantees that soil temperatures are smooth functions of position and time, even if the temperature coefficient or forcing function in the radiation boundary condition are discontinuous. Calculated soil temperature heat flux densities, and surface energy balance components for bare wet strips alternating with strips covered with either chalk, black plastic, or clear plastic were found to vary strongly with time and position. For diurnal variations, lateral heat flow only significantly affected temperatures in the middle of strips narrower than approximately 0.2 m. Sensitivity of soil temperature to changes in soil thermal properties increased as the temperature coefficient in the surface boundary condition decreased. Both cases showed that spatial differences in albedo, surface resistance, and serodynamic resistance spatially alter the surface energy balance and soil thermal regimes, including surface temperature and heat flux density

  14. UNSTEADY BOUNDARY LAYER FLOW ALONG A STRETCHING CYLINDER AN ANALYTICAL SOLUTION

    Directory of Open Access Journals (Sweden)

    M. Y. Akl

    2014-01-01

    Full Text Available The axisymetric laminar boundary layer unsteady flow along a continuously stretching cylinder immersed in a viscous and incompressible fluid is studied. The governing partial boundary layer equations in cylindrical form are first transformed into ordinary differential equations these equations are solved analytically using the optimal modified Homotopy Asymptotic method in order to get a closed form solution for the dimensionless functions f and è. The main object of this study is to investigate the effect of an unsteady motion of a stretching cylinder on the flow and heat transfer characteristics such as surface skin friction and surface heat flux. These characteristics have a direct effect on the quality of the final product of the fiber manufacturing and extrusion processes. Considerable effects were found for the dynamic parameter (γ, the curvature parameter (ρ and the prandtl number (pr on the velocity and the heat transfer.

  15. Analytical solutions for thermal forcing vortices in boundary layer and its applications

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-ran; LI Guo-ping

    2007-01-01

    Using the Boussinesq approximation, the vortex in the boundary layer is assumed to be axisymmetrical and thermal-wind balanced system forced by diabatic heating and friction, and is solved as an initial-value problem of linearized vortex equation set in cylindrical coordinates. The impacts of thermal forcing on the flow field structure of vortex are analyzed. It is found that thermal forcing has significant impacts on the flow field structure, and the material representative forms of these impacts are closely related to the radial distribution of heating. The discussion for the analytical solutions for the vortex in the boundary layer can explain some main structures of the vortex over the Tibetan Plateau.

  16. Approximate analytical solution to the Boussinesq equation with a sloping water-land boundary

    Science.gov (United States)

    Tang, Yuehao; Jiang, Qinghui; Zhou, Chuangbing

    2016-04-01

    An approximate solution is presented to the 1-D Boussinesq equation (BEQ) characterizing transient groundwater flow in an unconfined aquifer subject to a constant water variation at the sloping water-land boundary. The flow equation is decomposed to a linearized BEQ and a head correction equation. The linearized BEQ is solved using a Laplace transform. By means of the frozen-coefficient technique and Gauss function method, the approximate solution for the head correction equation can be obtained, which is further simplified to a closed-form expression under the condition of local energy equilibrium. The solutions of the linearized and head correction equations are discussed from physical concepts. Especially for the head correction equation, the well posedness of the approximate solution obtained by the frozen-coefficient method is verified to demonstrate its boundedness, which can be further embodied as the upper and lower error bounds to the exact solution of the head correction by statistical analysis. The advantage of this approximate solution is in its simplicity while preserving the inherent nonlinearity of the physical phenomenon. Comparisons between the analytical and numerical solutions of the BEQ validate that the approximation method can achieve desirable precisions, even in the cases with strong nonlinearity. The proposed approximate solution is applied to various hydrological problems, in which the algebraic expressions that quantify the water flow processes are derived from its basic solutions. The results are useful for the quantification of stream-aquifer exchange flow rates, aquifer response due to the sudden reservoir release, bank storage and depletion, and front position and propagation speed.

  17. Generalized analytical solution for advection-dispersion equation in finite spatial domain with arbitrary time-dependent inlet boundary condition

    Directory of Open Access Journals (Sweden)

    J.-S. Chen

    2011-04-01

    Full Text Available This study presents a generalized analytical solution for one-dimensional solute transport in finite spatial domain subject to arbitrary time-dependent inlet boundary condition. The governing equation includes terms accounting for advection, hydrodynamic dispersion, linear equilibrium sorption and first order decay processes. The generalized analytical solution is derived by using the Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate. Several special cases are presented and compared to illustrate the robustness of the derived generalized analytical solution. Result shows an excellent agreement. The analytical solutions of the special cases derived in this study have practical applications. Moreover, the derived generalized solution which consists an integral representation is evaluated by the numerical integration to extend its usage. The developed generalized solution offers a convenient tool for further development of analytical solution of specified time-dependent inlet boundary conditions or numerical evaluation of the concentration field for arbitrary time-dependent inlet boundary problem.

  18. Analytical solution of non-Fourier heat conduction problem on a fin under periodic boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadikia, H. [University of Isfahan, Isfahan (Iran, Islamic Republic of); Rismanian, M. [Bu-Ali Sina University, Hamadan (Iran, Islamic Republic of)

    2011-11-15

    Fourier and hyperbolic models of heat transfer on a fin that is subjected to a periodic boundary condition are solved analytically. The differential equation in Fourier and non-Fourier models is solved by the Laplace transform method. The temperature distribution on the fin is obtained using the residual theorem in a complex plan for the inverse Laplace transform method. The thermal shock is generated at the base of the fin, which moves toward the tip of the fin and is reflected from the tip. The current study of various parameters on the thermal shock location shows that relaxation time has a great influence on the temperature distribution on the fin. An unsteady boundary condition in the base fin caused the shock, which is generated continuously from the base and has interacted with the other reflected thermal shocks. Results of the current study show that the hyperbolic heat conduction equation can violate the second thermodynamic law under some unsteady boundary conditions.

  19. Analytical solution of non-Fourier heat conduction problem on a fin under periodic boundary conditions

    International Nuclear Information System (INIS)

    Fourier and hyperbolic models of heat transfer on a fin that is subjected to a periodic boundary condition are solved analytically. The differential equation in Fourier and non-Fourier models is solved by the Laplace transform method. The temperature distribution on the fin is obtained using the residual theorem in a complex plan for the inverse Laplace transform method. The thermal shock is generated at the base of the fin, which moves toward the tip of the fin and is reflected from the tip. The current study of various parameters on the thermal shock location shows that relaxation time has a great influence on the temperature distribution on the fin. An unsteady boundary condition in the base fin caused the shock, which is generated continuously from the base and has interacted with the other reflected thermal shocks. Results of the current study show that the hyperbolic heat conduction equation can violate the second thermodynamic law under some unsteady boundary conditions

  20. On the analytical solution of the SN equation in a rectangle assuming an exponential exiting angular flux boundary

    International Nuclear Information System (INIS)

    In this work, we report an analytical solution for the set of SN equations for the angular flux, in a rectangle, using the double Laplace transform technique. Its main idea comprehends the steps: application of the Laplace transform in one space variable, solution of the resulting equation by the LTSN method and reconstruction of the double Laplace transformed angular flux using the inversion theorem of the Laplace transform. We must emphasize that we perform the Laplace inversion by the LTSN method in the x direction, meanwhile we evaluate the inversion in the y direction performing the calculation of the corresponding line integral solution by the Stefest method. We have also to figure out that the application of Laplace transform to this type of boundary value problem introduces additional unknown functions associated to the partial derivatives of the angular flux at boundary. Based on the good results attained by the nodal LTSN method, we assume that the angular flux at boundary is also approximated by an exponential function. By analytical we mean that no approximation is done along the solution derivation except for the exponential hypothesis for the exiting angular flux at boundary. For sake of completeness, we report numerical comparisons of the obtained results against the ones of the literature. (author)

  1. An analytical solution for simulation of the fission gas behaviors with time-dependent piece-wise boundary resolution

    Energy Technology Data Exchange (ETDEWEB)

    Cui Yi; Huo Yongzhong [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China); Ding Shurong, E-mail: dsr1971@163.com [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China) and Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institution of China, Chengdu 610041, Sichuan (China); Zhang Lin; Li Yuanming [Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institution of China, Chengdu 610041, Sichuan (China)

    2012-05-15

    An analytical solution of gas concentration for the equivalent spherical grain is obtained first in Laplace space, then the inverse-Laplace transformed solution is further developed. The corresponding analytical expressions for the grain boundary gaseous swelling and the fission gas release in UO{sub 2} nuclear fuels are developed in the absence of grain growth. The following phenomena and assumptions are taken into account in our model, including the gas atom diffusion, saturation and the time-varying piece-wise inter-granular resolution. The explicit expression for saturation time of the grain boundary gas atoms is also obtained. Our approximated analytical solutions for the fission gas behaviors are validated through comparison with those solved by finite difference method. Good agreement has been achieved for the cases with different input parameters. Based on the developed analytical solutions, the effects of the grain sizes and the external pressure on the fission gas behaviors are investigated. This study lays a foundation for the multi-scale simulation of the thermo-mechanical behaviors in nuclear fuel elements.

  2. An analytical solution for simulation of the fission gas behaviors with time-dependent piece-wise boundary resolution

    International Nuclear Information System (INIS)

    An analytical solution of gas concentration for the equivalent spherical grain is obtained first in Laplace space, then the inverse-Laplace transformed solution is further developed. The corresponding analytical expressions for the grain boundary gaseous swelling and the fission gas release in UO2 nuclear fuels are developed in the absence of grain growth. The following phenomena and assumptions are taken into account in our model, including the gas atom diffusion, saturation and the time-varying piece-wise inter-granular resolution. The explicit expression for saturation time of the grain boundary gas atoms is also obtained. Our approximated analytical solutions for the fission gas behaviors are validated through comparison with those solved by finite difference method. Good agreement has been achieved for the cases with different input parameters. Based on the developed analytical solutions, the effects of the grain sizes and the external pressure on the fission gas behaviors are investigated. This study lays a foundation for the multi-scale simulation of the thermo-mechanical behaviors in nuclear fuel elements.

  3. Analytical solutions of the one-dimensional advection-dispersion solute transport equation subject to time-dependent boundary conditions

    Science.gov (United States)

    Analytical solutions of the advection-dispersion solute transport equation remain useful for a large number of applications in science and engineering. In this paper we extend the Duhamel theorem, originally established for diffusion type problems, to the case of advective-dispersive transport subj...

  4. Analytical solution for beam with time-dependent boundary conditions versus response spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Gou, P.F.; Panahi, K.K. [GE Nuclear Energy, San Jose, CA (United States)

    2001-07-01

    This paper studies the responses of a uniform simple beam for which the supports are subjected to time-dependent conditions. Analytical solution in terms of series was presented for two cases: (1) Two supports of a simple beam are subjected to a harmonic motion, and (2) One of the two supports is stationary while the other is subjected to a harmonic motion. The results of the analytical solution were investigated and compared with the results of conventional response spectrum method using the beam finite element model. One of the applications of the results presented in this paper can be used to assess the adequacy and accuracy of the engineering approaches such as response spectra methods. It has been found that, when the excitation frequency equals the fundamental frequency of the beam, the results from response spectrum method are in good agreement with the exact calculation. The effects of initial conditions on the responses are also examined. It seems that the non-zero initial velocity has pronounced effects on the displacement time histories but it has no effect on the maximum accelerations. (author)

  5. An analytical solution for the monoenergetic diffusion equation in a multilayered slab: determination of albedo boundary condition

    International Nuclear Information System (INIS)

    In this work, we solve analytically, without losing generality, the neutron diffusion equation for monoenergetic neutrons in a multilayered slab. To this end, we initially determine the solution of the neutron diffusion equation for a generic slab using standard results of second order linear ordinary differential equation with constant coefficients. The global solution for the multilayered slab is then determined applying the boundary condition and continuity of the flux and current at interface. Once the neutron flux is known, the albedo boundary condition is straightly obtained for an arbitrary number of layers in the baffle-reflecting regions, by just using the definition of albedo. We also present numerical simulation for the results neutron flux and comparison with the in literature. (author)

  6. Analytical Solution of Thermal Wave Models on Skin Tissue Under Arbitrary Periodic Boundary Conditions

    Science.gov (United States)

    Fazlali, R.; Ahmadikia, H.

    2013-01-01

    Modeling and understanding the heat transfer in biological tissues is important in medical thermal therapeutic applications. The biothermomechanics of skin involves interdisciplinary features, such as bioheat transfer, biomechanics, and burn damage. The hyperbolic thermal wave model of bioheat transfer and the parabolic Pennes bioheat transfer equations with blood perfusion and metabolic heat generation are applied for the skin tissue as a finite and semi-infinite domain when the skin surface temperature is suddenly exposed to a source of an arbitrary periodic temperature. These equations are solved analytically by Laplace transform methods. The thermal wave model results indicate that a non-Fourier model has predicted the thermal behavior correctly, compared to that of previous experiments. The results of the thermal wave model show that when the first thermal wave moves from the first boundary, the temperature profiles for finite and semi-infinite domains of skin become separated for these phenomena; the discrepancy between these profiles is negligible. The accuracy of the obtained results is validated through comparisons with existing numerical results. The results demonstrate that the non-Fourier model is significant in describing the thermal behavior of skin tissue.

  7. Analytic solution for magnetohydrodynamic boundary layer flow of Casson fluid over a stretching/shrinking sheet with wall mass transfer

    Institute of Scientific and Technical Information of China (English)

    Krishnendu Bhattacharyya; Tasawar Hayat; Ahmed Alsaedi

    2013-01-01

    In this analysis,the magnetohydrodynamic boundary layer flow of Casson fluid over a permeable stretching/shrinking sheet in the presence of wall mass transfer is studied.Using similarity transformations,the governing equations are converted to an ordinary differential equation and then solved analytically.The introduction of a magnetic field changes the behavior of the entire flow dynamics in the shrinking sheet case and also has a major impact in the stretching sheet case.The similarity solution is always unique in the stretching case,and in the shrinking case the solution shows dual nature for certain values of the parameters.For stronger magnetic field,the similarity solution for the shrinking sheet case becomes unique.

  8. Analytical solutions to the fractional advection-diffusion equation with time-dependent pulses on the boundary

    Science.gov (United States)

    Rubbab, Qammar; Mirza, Itrat Abbas; Qureshi, M. Zubair Akbar

    2016-07-01

    The time-fractional advection-diffusion equation with Caputo-Fabrizio fractional derivatives (fractional derivatives without singular kernel) is considered under the time-dependent emissions on the boundary and the first order chemical reaction. The non-dimensional problem is formulated by using suitable dimensionless variables and the fundamental solutions to the Dirichlet problem for the fractional advection-diffusion equation are determined using the integral transforms technique. The fundamental solutions for the ordinary advection-diffusion equation, fractional and ordinary diffusion equation are obtained as limiting cases of the previous model. Using Duhamel's principle, the analytical solutions to the Dirichlet problem with time-dependent boundary pulses have been obtained. The influence of the fractional parameter and of the drift parameter on the solute concentration in various spatial positions was analyzed by numerical calculations. It is found that the variation of the fractional parameter has a significant effect on the solute concentration, namely, the memory effects lead to the retardation of the mass transport.

  9. An Analytical Solution of the Radiative Transfer Equation for Inhomogeneous Finite Medium with Fresnel Boundary Conditions

    International Nuclear Information System (INIS)

    The problem of radiation transfer through an inhomogeneous finite medium with internal energy sources and diffusely and specular reflecting boundary conditions is considered (problem 1). The partial heat fluxes for this problem are given in terms of the albedo of the source-free problem with specular-reflecting boundaries (problem 2). We assume that the reflectivity of the surfaces dependent upon the refractive indices and is considered as Fresnel’s reflection probability function. The Pomading-Eddington method is used to calculate first the albedo s for problem 2 and then calculate the partial heat fluxes for problem 1. Results are obtained for isotropic scattering in a homogeneous and an inhomogeneous media for uniform and non-uniform internal sources and are compared with the published calculations.

  10. Analytical solutions for the surface response to small amplitude perturbations in boundary data in the shallow-ice-stream approximation

    Directory of Open Access Journals (Sweden)

    G. H. Gudmundsson

    2008-07-01

    Full Text Available New analytical solutions describing the effects of small-amplitude perturbations in boundary data on flow in the shallow-ice-stream approximation are presented. These solutions are valid for a non-linear Weertman-type sliding law and for Newtonian ice rheology. Comparison is made with corresponding solutions of the shallow-ice-sheet approximation, and with solutions of the full Stokes equations. The shallow-ice-stream approximation is commonly used to describe large-scale ice stream flow over a weak bed, while the shallow-ice-sheet approximation forms the basis of most current large-scale ice sheet models. It is found that the shallow-ice-stream approximation overestimates the effects of bed topography perturbations on surface profile for wavelengths less than about 5 to 10 ice thicknesses, the exact number depending on values of surface slope and slip ratio. For high slip ratios, the shallow-ice-stream approximation gives a very simple description of the relationship between bed and surface topography, with the corresponding transfer amplitudes being close to unity for any given wavelength. The shallow-ice-stream estimates for the timescales that govern the transient response of ice streams to external perturbations are considerably more accurate than those based on the shallow-ice-sheet approximation. In particular, in contrast to the shallow-ice-sheet approximation, the shallow-ice-stream approximation correctly reproduces the short-wavelength limit of the kinematic phase speed given by solving a linearised version of the full Stokes system. In accordance with the full Stokes solutions, the shallow-ice-sheet approximation predicts surface fields to react weakly to spatial variations in basal slipperiness with wavelengths less than about 10 to 20 ice thicknesses.

  11. Indirect boundary element method for three dimensional problems. Analytical solution for contribution to wave field by triangular element; Sanjigen kansetsu kyokai yosoho. Sankakukei yoso no kiyo no kaisekikai

    Energy Technology Data Exchange (ETDEWEB)

    Yokoi, T. [Building Research Institute, Tokyo (Japan); Sanchez-Sesma, F. [Universidad National Autonoma de Mexico, (Mexico). Institute de Ingenieria

    1997-05-27

    Formulation is introduced for discretizing a boundary integral equation into an indirect boundary element method for the solution of 3-dimensional topographic problems. Yokoi and Takenaka propose an analytical solution-capable reference solution (solution for the half space elastic body with flat free surface) to problems of topographic response to seismic motion in a 2-dimensional in-plane field. That is to say, they propose a boundary integral equation capable of effectively suppressing the non-physical waves that emerge in the result of computation in the wake of the truncation of the discretized ground surface making use of the wave field in a semi-infinite elastic body with flat free surface. They apply the proposed boundary integral equation discretized into the indirect boundary element method to solve some examples, and succeed in proving its validity. In this report, the equation is expanded to deal with 3-dimensional topographic problems. A problem of a P-wave vertically landing on a flat and free surface is solved by the conventional boundary integral equation and the proposed boundary integral equation, and the solutions are compared with each other. It is found that the new method, different from the conventional one, can delete non-physical waves from the analytical result. 4 figs.

  12. Existence and Analytic Approximation of Solutions of Duffing Type Nonlinear Integro-Differential Equation with Integral Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Alsaedi Ahmed

    2009-01-01

    Full Text Available A generalized quasilinearization technique is developed to obtain a sequence of approximate solutions converging monotonically and quadratically to a unique solution of a boundary value problem involving Duffing type nonlinear integro-differential equation with integral boundary conditions. The convergence of order for the sequence of iterates is also established. It is found that the work presented in this paper not only produces new results but also yields several old results in certain limits.

  13. Analytical solution of buoyancy-driven flow and heat transfer in a vertical channel with spatially periodic boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gunes, Hasan [Department of Mechanical Engineering, Istanbul Technical University, Gumussuyu (Turkey)

    2003-12-01

    In this study, we derive analytical expressions describing the variation of field variables in steady, 2-D and 3-D natural convection in a vertical channel with discrete in-space, flush-mounted heat sources. The expressions are valid for sufficiently small Grasof numbers. The solution are governed by the following dimensionless parameters: aspect ratios defining the geometry of the problem, Prandtl number, Grashof number and dimensionless channel reference temperature. Test case solutions are obtained numerically to assess the accuracy of the derived expressions. For small values Gr, the derived expressions are in excellent agreement with the numerical solutions in the entire computational domain. Analytical expressions for the net volume flow rate through the channel and Nusselt number variation are also given. (orig.)

  14. On the analytical solution of the S{sub N} equation in a rectangle assuming an exponential exiting angular flux boundary

    Energy Technology Data Exchange (ETDEWEB)

    Goncalez, Tifani T. [Universidade Federal do Rio Grande do Sul (PROMEC/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Segatto, Cynthia F.; Vilhena, Marco Tullio, E-mail: csegatto@pq.cnpq.b, E-mail: vilhena@pq.cnpq.b [Universidade Federal do Rio Grande do Sul (DMPA/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Matematica Aplicada

    2011-07-01

    In this work, we report an analytical solution for the set of S{sub N} equations for the angular flux, in a rectangle, using the double Laplace transform technique. Its main idea comprehends the steps: application of the Laplace transform in one space variable, solution of the resulting equation by the LTS{sub N} method and reconstruction of the double Laplace transformed angular flux using the inversion theorem of the Laplace transform. We must emphasize that we perform the Laplace inversion by the LTS{sub N} method in the x direction, meanwhile we evaluate the inversion in the y direction performing the calculation of the corresponding line integral solution by the Stefest method. We have also to figure out that the application of Laplace transform to this type of boundary value problem introduces additional unknown functions associated to the partial derivatives of the angular flux at boundary. Based on the good results attained by the nodal LTS{sub N} method, we assume that the angular flux at boundary is also approximated by an exponential function. By analytical we mean that no approximation is done along the solution derivation except for the exponential hypothesis for the exiting angular flux at boundary. For sake of completeness, we report numerical comparisons of the obtained results against the ones of the literature. (author)

  15. Heat Generation/Absorption Effects in a Boundary Layer Stretched Flow of Maxwell Nanofluid: Analytic and Numeric Solutions.

    Directory of Open Access Journals (Sweden)

    Muhammad Awais

    Full Text Available Analysis has been done to investigate the heat generation/absorption effects in a steady flow of non-Newtonian nanofluid over a surface which is stretching linearly in its own plane. An upper convected Maxwell model (UCM has been utilized as the non-Newtonian fluid model in view of the fact that it can predict relaxation time phenomenon which the Newtonian model cannot. Behavior of the relaxations phenomenon has been presented in terms of Deborah number. Transport phenomenon with convective cooling process has been analyzed. Brownian motion "Db" and thermophoresis effects "Dt" occur in the transport equations. The momentum, energy and nanoparticle concentration profiles are examined with respect to the involved rheological parameters namely the Deborah number, source/sink parameter, the Brownian motion parameters, thermophoresis parameter and Biot number. Both numerical and analytic solutions are presented and found in nice agreement. Comparison with the published data is also made to ensure the validity. Stream lines for Maxwell and Newtonian fluid models are presented in the analysis.

  16. Unified analytical solution for various boundary conditions for the coupled flexural-torsional vibration of beams subjected to axial loads and end moments

    Science.gov (United States)

    Joshi, A.; Suryanarayan, S.

    1989-03-01

    The problem of free vibration of beams having different end conditions and subjected to static initial loads has been studied with the aim of arriving at good closed-form analytical solutions. Elementary beam theory is used as a starting point to obtain the transverse vibration frequencies for various cases of classical homogeneous end conditions and for various values of the static axial load and end moment. These results indicate that it is possible to identify simple algebraic expressions which accurately represent the solution for various boundary conditions. It is also found that reasonably accurate estimates of the predominantly flexural frequency of coupled flexural-torsional vibration can be obtained from the uncoupled flexural vibration frequency of beam-columns. This is achieved by defining an effective axial load parameter, which is a combination of the axial load, the end moment and the slenderness parameter. Finally, the study also brings out that the various expressions, corresponding to different end conditions, can be combined together into a single expression for the predominantly flexural frequency. This expression is common for the boundary conditions considered here and use is made of various normalizing factors which depend on the boundary conditions, and are obtainable from the corresponding free vibration and stability analyses of beam-columns.

  17. Analytical Solution of Melting in a Subcooled Semi-infinite Solid with Boundary Conditions of the Second Kind

    Institute of Scientific and Technical Information of China (English)

    1993-01-01

    The melting problem in a semi-infinite region with constant heat flux boundary condition is solved by a semi-exact method and an integral approximate method .Effect of subcooling on the transient solid-liquid interface location and surface temperature are also discussed in this paper.

  18. Comparison of Different Analytic Solutions to Axisymmetric Squeezing Fluid Flow between Two Infinite Parallel Plates with Slip Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Hamid Khan

    2012-01-01

    Full Text Available We investigate squeezing flow between two large parallel plates by transforming the basic governing equations of the first grade fluid to an ordinary nonlinear differential equation using the stream functions ur(r,z,t=(1/r(∂ψ/∂z and uz(r,z,t=−(1/r(∂ψ/∂r and a transformation ψ(r,z=r2F(z. The velocity profiles are investigated through various analytical techniques like Adomian decomposition method, new iterative method, homotopy perturbation, optimal homotopy asymptotic method, and differential transform method.

  19. Boundary-value problems for x-analytical functions with weighted boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kapshivyi, A.A. [Kiev Univ. (Ukraine)

    1994-11-10

    We consider boundary-value problems for x-analytical functions of a complex variable z = x + iy in a number of domains. Limit values with the weight (ln x){sup {minus}1} are given for the real part of the x-analytical function on the sections of the boundary that follow the imaginary axis, and simple limits are given for the real part of the x-analytical functions on the part of the boundary outside the imaginary axis. The apparatus of integral representations of x-analytical functions is applied to obtain a solution of the problem in quadratures.

  20. Strongly nonlinear oscillators analytical solutions

    CERN Document Server

    Cveticanin, Livija

    2014-01-01

    This book provides the presentation of the motion of pure nonlinear oscillatory systems and various solution procedures which give the approximate solutions of the strong nonlinear oscillator equations. The book presents the original author’s method for the analytical solution procedure of the pure nonlinear oscillator system. After an introduction, the physical explanation of the pure nonlinearity and of the pure nonlinear oscillator is given. The analytical solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter is considered. Special attention is given to the one and two mass oscillatory systems with two-degrees-of-freedom. The criteria for the deterministic chaos in ideal and non-ideal pure nonlinear oscillators are derived analytically. The method for suppressing chaos is developed. Important problems are discussed in didactic exercises. The book is self-consistent and suitable as a textbook for students and also for profess...

  1. Analytic anisotropic solution for holography

    CERN Document Server

    Ren, Jie

    2016-01-01

    An exact solution to Einstein's equations for holographic models is presented and studied. The IR geometry has a timelike cousin of the Kasner singularity, which is the less generic case of the BKL (Belinski-Khalatnikov-Lifshitz) singularity, and the UV is asymptotically AdS. This solution describes a holographic RG flow between them. The solution's appearance is an interpolation between the planar AdS black hole and the AdS soliton. The causality constraint is always satisfied. The boundary condition for the current-current correlation function and the Laplacian in the IR is examined in detail. There is no infalling wave in the IR, but instead, there is a normalizable solution in the IR. In a special case, a hyperscaling-violating geometry is obtained after a dimension reduction.

  2. An analytical model for stress-induced grain growth in the presence of both second-phase particles and solute segregation at grain boundaries

    International Nuclear Information System (INIS)

    A theoretical framework that incorporates the influence of second-phase particles and solute segregation at grain boundaries (GBs) on stress-induced GB migration and grain rotation is formulated in the present paper. In our work, we modified the well-established Cahn–Taylor model to account for the drag stresses generated by second-phase particles and by solute atoms segregated at GBs. The theoretical framework is then implemented to rationalize GB migration and grain rotation using experimental data from a previously published study on stress-induced grain growth in the presence of both second-phase particles and solute segregation at GBs. The calculated grain growth results are generally consistent with the experimental data, providing support to the proposed theoretical model, despite the various assumptions involved. Moreover, the influence of second-phase particles and solute segregation at GBs on GB migration and grain rotation was also investigated using the model, and our results suggest that both second-phase particles and solute atoms segregated at GBs reduce the velocities of GB migration and grain rotation as compared to those in the case of high-purity Al

  3. Analytic prediction for planar turbulent boundary layers

    CERN Document Server

    Chen, Xi

    2016-01-01

    Analytic predictions of mean velocity profile (MVP) and streamwise ($x$) development of related integral quantities are presented for flows in channel and turbulent boundary layer (TBL), based on a symmetry analysis of eddy length and total stress. Specific predictions are the friction velocity $u_\\tau$: ${ U_e/u_\\tau }\\approx 2.22\\ln Re_x+2.86-3.83\\ln(\\ln Re_x)$; the boundary layer thickness $\\delta_e$: $x/\\delta_e \\approx 7.27\\ln Re_x-5.18-12.52\\ln(\\ln Re_x)$; the momentum thickness Reynolds number: $Re_x/Re_\\theta=4.94[{(\\ln {{\\mathop{\\rm Re}\

  4. Analyticity of thermoelastic plates with dynamical boundary conditions

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Qiong(张琼); HUANG; Falun(黄发伦)

    2003-01-01

    We consider a thermoelastic plate with dynamical boundary conditions. Using the contradictionargument of Pazy's well-known analyticity criterion and P.D.E. estimates, we prove that the corresponding C0semigroup is analytic, hence exponentially stable.

  5. Analytical solutions for problems of bubble dynamics

    International Nuclear Information System (INIS)

    Recently, an asymptotic solution of the Rayleigh equation for an empty bubble in N dimensions has been obtained. Here we give the closed-form general analytical solution of this equation. We also find the general solution of the Rayleigh equation in N dimensions for the case of a gas-filled hyperspherical bubble. In addition, we include a surface tension into consideration. - Highlights: • The Rayleigh equation for bubble's dynamics is considered. • General analytical solutions of the Rayleigh equation are obtained. • Various types of analytical solutions of the Rayleigh equation are studied

  6. Analytical solutions to flexural vibration of slender piezoelectric multilayer cantilevers

    International Nuclear Information System (INIS)

    The modeling of vibration of piezoelectric cantilevers has often been based on passive cantilevers of a homogeneous material. Although piezoelectric cantilevers and passive cantilevers share certain characteristics, this method has caused confusion in incorporating the piezoelectric moment into the differential equation of motion. The extended Hamilton’s principle is a fundamental approach to modeling flexural vibration of multilayer piezoelectric cantilevers. Previous works demonstrated derivation of the differential equation of motion using this approach; however, proper analytical solutions were not reported. This was partly due to the fact that the differential equation derived by the extended Hamilton’s principle is a boundary-value problem with nonhomogeneous boundary conditions which cannot be solved by modal analysis. In the present study, an analytical solution to the boundary-value problem was obtained by transforming it into a new problem with homogeneous boundary conditions. After the transformation, modal analysis was used to solve the new boundary-value problem. The analytical solutions for unimorphs and bimorphs were verified with three-dimensional finite element analysis (FEA). Deflection profiles and frequency response functions under voltage, uniform pressure and tip force were compared. Discrepancies between the analytical results and FEA results were within 3.5%. Following model validation, parametric studies were conducted to investigate the effects of thickness of electrodes and piezoelectric layers, and the piezoelectric coupling coefficient d 31 on the performance of piezoelectric cantilever actuators. (paper)

  7. Analytical solution to one-dimensional consolidation in unsaturated soils

    Institute of Scientific and Technical Information of China (English)

    QIN Ai-fang; CHEN Guang-jing; TAN Yong-wei; SUN Dean

    2008-01-01

    This paper presents an analytical solution of the one-dimensional consolidation in unsaturated soil with a finite thickness under vertical loading and confinements in the lateral directions. The boundary contains the top surface permeable to water and air and the bottom impermeable to water and air. The analytical solution is for Fredlund's one-dimensionai consolidation equation in unsaturated soils. The transfer relationship between the state vectors at top surface and any depth is obtained by using the Laplace transform and Cayley-Hamilton mathematical methods to the governing equations of water and air, Darcy's law and Fick's law. Excess pore-air pressure, excess pore-water pressure and settlement in the Laplace-transformed domain are obtained by using the Laplace transform with the initial conditions and boundary conditions. By performing inverse Laplace transforms, the analytical solutions are obtained in the time domain. A typical example illustrates the consolidation characteristics of unsaturated soft from analytical results. Finally, comparisons between the analytical solutions and results of the finite difference method indicate that the analytical solution is correct.

  8. Transient solute drag in migrating grain boundaries

    International Nuclear Information System (INIS)

    Understanding the solute drag in migrating grain boundaries or interfaces has been a topic in materials research since Cahn's seminal paper in 1962. However, mostly steady-state solutions for solute segregation and drag in a migrating interface have been investigated. Here a new concept, based on the thermodynamic extremal principle, is introduced, which allows a detailed study of the transient processes in the migrating interface starting from a given initial configuration. The system is then described by two parameters, the first representing the amount of segregated solute in the grain boundary and the second the grain boundary position. Stability studies are performed using the perturbation concept. The model is demonstrated by simulations for a Fe-0.1 at.% Ni alloy taking different values for the grain boundary mobility and the driving force.

  9. Analytical solutions for problems of bubble dynamics

    CERN Document Server

    Kudryashov, Nikolai A

    2016-01-01

    Recently, an asymptotic solution of the Rayleigh equation for an empty bubble in $N$ dimensions has been obtained. Here we give the closed--from general analytical solution of this equation. We also find the general solution of the Rayleigh equation in $N$ dimensions for the case of a gas--filled hyperspherical bubble. In addition, we include a surface tension into consideration.

  10. Unique solution to periodic boundary value problems

    Directory of Open Access Journals (Sweden)

    Yong Sun

    1991-01-01

    Full Text Available Existence of unique solution to periodic boundary value problems of differential equations with continuous or discontinuous right-hand side is considered by utilizing the method of lower and upper solutions and the monotone properties of the operator. This is subject to discussion in the present paper.

  11. The boundary value problem for discrete analytic functions

    KAUST Repository

    Skopenkov, Mikhail

    2013-06-01

    This paper is on further development of discrete complex analysis introduced by R.Isaacs, J.Ferrand, R.Duffin, and C.Mercat. We consider a graph lying in the complex plane and having quadrilateral faces. A function on the vertices is called discrete analytic, if for each face the difference quotients along the two diagonals are equal.We prove that the Dirichlet boundary value problem for the real part of a discrete analytic function has a unique solution. In the case when each face has orthogonal diagonals we prove that this solution uniformly converges to a harmonic function in the scaling limit. This solves a problem of S.Smirnov from 2010. This was proved earlier by R.Courant-K.Friedrichs-H.Lewy and L.Lusternik for square lattices, by D.Chelkak-S.Smirnov and implicitly by P.G.Ciarlet-P.-A.Raviart for rhombic lattices.In particular, our result implies uniform convergence of the finite element method on Delaunay triangulations. This solves a problem of A.Bobenko from 2011. The methodology is based on energy estimates inspired by alternating-current network theory. © 2013 Elsevier Ltd.

  12. Iterative solution of Hermite boundary integral equations

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Leonard J [ORNL; Nintcheu Fata, Sylvain [ORNL; Ma, Ding [ORNL

    2008-01-01

    An efficient iterative method for the solution of the linear equations arising from a Hermite boundary integral approximation has been developed. Along with equations for the boundary unknowns, the Hermite system incorporates equations for the first-order surface derivatives (gradient) of the potential, and is therefore substantially larger than the matrix for a corresponding linear approximation. However, by exploiting the structure of the Hermite matrix, a two-level iterative algorithm has been shown to provide a very efficient solution algorithm. In this approach, the boundary function unknowns are treated separately from the gradient, taking advantage of the sparsity and near-positive definiteness of the gradient equations. In test problems, the new algorithm significantly reduced computation time compared to iterative solution applied to the full matrix. This approach should prove to be even more effective for the larger systems encountered in three-dimensional analysis, and increased efficiency should come from pre-conditioning of the non-sparse matrix component.

  13. Analytical solution methods for geodesic motion

    CERN Document Server

    Hackmann, Eva

    2015-01-01

    The observation of the motion of particles and light near a gravitating object is until now the only way to explore and to measure the gravitational field. In the case of exact black hole solutions of the Einstein equations the gravitational field is characterized by a small number of parameters which can be read off from the observables related to the orbits of test particles and light rays. Here we review the state of the art of analytical solutions of geodesic equations in various space--times. In particular we consider the four dimensional black hole space--times of Pleba\\'nski--Demia\\'nski type as far as the geodesic equation separates, as well as solutions in higher dimensions, and also solutions with cosmic strings. The mathematical tools used are elliptic and hyperelliptic functions. We present a list of analytic solutions which can be found in the literature.

  14. Analytic vortex solutions on compact hyperbolic surfaces

    Science.gov (United States)

    Maldonado, Rafael; Manton, Nicholas S.

    2015-06-01

    We construct, for the first time, abelian Higgs vortices on certain compact surfaces of constant negative curvature. Such surfaces are represented by a tessellation of the hyperbolic plane by regular polygons. The Higgs field is given implicitly in terms of Schwarz triangle functions and analytic solutions are available for certain highly symmetric configurations.

  15. Analytic vortex solutions on compact hyperbolic surfaces

    International Nuclear Information System (INIS)

    We construct, for the first time, abelian Higgs vortices on certain compact surfaces of constant negative curvature. Such surfaces are represented by a tessellation of the hyperbolic plane by regular polygons. The Higgs field is given implicitly in terms of Schwarz triangle functions and analytic solutions are available for certain highly symmetric configurations. (paper)

  16. Analytic vortex solutions on compact hyperbolic surfaces

    CERN Document Server

    Maldonado, R

    2015-01-01

    We construct, for the first time, Abelian-Higgs vortices on certain compact surfaces of constant negative curvature. Such surfaces are represented by a tessellation of the hyperbolic plane by regular polygons. The Higgs field is given implicitly in terms of Schwarz triangle functions and analytic solutions are available for certain highly symmetric configurations.

  17. Analytic Solutions of Elastic Tunneling Problems

    NARCIS (Netherlands)

    Strack, O.E.

    2002-01-01

    The complex variable method for solving two dimensional linearly elastic problems is used to obtain several fundamental analytical solutions of tunneling problems. The method is used to derive the general mathematical representation of problems involving resultant forces on holes in a half-plane

  18. Analytic solutions of an unclassified artifact /

    Energy Technology Data Exchange (ETDEWEB)

    Trent, Bruce C.

    2012-03-01

    This report provides the technical detail for analytic solutions for the inner and outer profiles of the unclassified CMM Test Artifact (LANL Part Number 157Y-700373, 5/03/2001) in terms of radius and polar angle. Furthermore, analytic solutions are derived for the legacy Sheffield measurement hardware, also in terms of radius and polar angle, using part coordinates, i.e., relative to the analytic profile solutions obtained. The purpose of this work is to determine the exact solution for the “cosine correction” term inherent to measurement with the Sheffield hardware. The cosine correction is required in order to interpret the actual measurements taken by the hardware in terms of an actual part definition, or “knot-point spline definition,” that typically accompanies a component drawing. Specifically, there are two portions of the problem: first an analytic solution must be obtained for any point on the part, e.g., given the radii and the straight lines that define the part, it is required to find an exact solution for the inner and outer profile for any arbitrary polar angle. Next, the problem of the inspection of this part must be solved, i.e., given an arbitrary sphere (representing the inspection hardware) that comes in contact with the part (inner and outer profiles) at any arbitrary polar angle, it is required to determine the exact location of that intersection. This is trivial for the case of concentric circles. In the present case, however, the spherical portion of the profiles is offset from the defined center of the part, making the analysis nontrivial. Here, a simultaneous solution of the part profiles and the sphere was obtained.

  19. Can We Remove Secular Terms for Analytical Solution of Groundwater Response under Tidal Influence?

    CERN Document Server

    Munusamy, Selva Balaji

    2016-01-01

    This paper presents a secular term removal methodology based on the homotopy perturbation method for analytical solutions of nonlinear problems with periodic boundary condition. The analytical solution for groundwater response to tidal fluctuation in a coastal unconfined aquifer system with the vertical beach is provided as an example. The non-linear one-dimensional Boussinesq's equation is considered as the governing equation for the groundwater flow. An analytical solution is provided for non-dimensional Boussinesq's equation with cosine harmonic boundary condition representing tidal boundary condition. The analytical solution is obtained by using homotopy perturbation method with a virtual embedding parameter. The present approach does not require pre-specified perturbation parameter and also facilitates secular terms elimination in the perturbation solution. The solutions starting from zeroth-order up to third-order are obtained. The non-dimensional expression, $A/D_{\\infty}$ emerges as an implicit parame...

  20. Non-perturbative solution of free-convective boundary-layer equation by Adomian decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    Kechil, Seripah Awang [Department of Mathematics, Universiti Teknologi MARA, 40450 Shah Alam Selangor (Malaysia); Hashim, Ishak [School of Mathematical Sciences, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia)]. E-mail: ishak_h@ukm.my

    2007-03-19

    A free-convective boundary layer flow modeled by a system of nonlinear ordinary differential equations is considered. The system is solved using the Adomian decomposition method (ADM) which yields an analytic solution in the form of a rapidly convergent infinite series with easily computable terms. The analytical solutions and the pertinent features of the illustrations show the efficiency of the method.

  1. Analytic Solutions of Elastic Tunneling Problems

    OpenAIRE

    Strack, O.E.

    2002-01-01

    The complex variable method for solving two dimensional linearly elastic problems is used to obtain several fundamental analytical solutions of tunneling problems. The method is used to derive the general mathematical representation of problems involving resultant forces on holes in a half-plane. Such problems are encountered in geomechanics during the excavation of tunnels. When tunnels are excavated the removal of the weighted material inside the tunnel causes the ground under the tunnel to...

  2. Exact Solutions of Chemically Reactive Solute Distribution in MHD Boundary Layer Flow over a Shrinking Surface

    International Nuclear Information System (INIS)

    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 mass flux (PMF) as boundary conditions. The study reveals that the concentration over a shrinking sheet is significantly different from that of a stretching surface. It is found that the solute boundary layer thickness is enhanced with the increasing values of the Schmidt number and the power-law index parameter, but decreases with enhanced values 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. (fundamental areas of phenomenology(including applications))

  3. Large deflection of clamped circular plate and accuracy of its approximate analytical solutions

    Science.gov (United States)

    Zhang, Yin

    2016-02-01

    A different set of governing equations on the large deflection of plates are derived by the principle of virtual work (PVW), which also leads to a different set of boundary conditions. Boundary conditions play an important role in determining the computation accuracy of the large deflection of plates. Our boundary conditions are shown to be more appropriate by analyzing their difference with the previous ones. The accuracy of approximate analytical solutions is important to the bulge/blister tests and the application of various sensors with the plate structure. Different approximate analytical solutions are presented and their accuracies are evaluated by comparing them with the numerical results. The error sources are also analyzed. A new approximate analytical solution is proposed and shown to have a better approximation. The approximate analytical solution offers a much simpler and more direct framework to study the plate-membrane transition behavior of deflection as compared with the previous approaches of complex numerical integration.

  4. Approximate Analytic Solutions for the Two-Phase Stefan Problem Using the Adomian Decomposition Method

    Directory of Open Access Journals (Sweden)

    Xiao-Ying Qin

    2014-01-01

    Full Text Available An Adomian decomposition method (ADM is applied to solve a two-phase Stefan problem that describes the pure metal solidification process. In contrast to traditional analytical methods, ADM avoids complex mathematical derivations and does not require coordinate transformation for elimination of the unknown moving boundary. Based on polynomial approximations for some known and unknown boundary functions, approximate analytic solutions for the model with undetermined coefficients are obtained using ADM. Substitution of these expressions into other equations and boundary conditions of the model generates some function identities with the undetermined coefficients. By determining these coefficients, approximate analytic solutions for the model are obtained. A concrete example of the solution shows that this method can easily be implemented in MATLAB and has a fast convergence rate. This is an efficient method for finding approximate analytic solutions for the Stefan and the inverse Stefan problems.

  5. Comparison between analytical and numerical solution of mathematical drying model

    Science.gov (United States)

    Shahari, N.; Rasmani, K.; Jamil, N.

    2016-02-01

    Drying is often related to the food industry as a process of shifting heat and mass inside food, which helps in preserving food. Previous research using a mass transfer equation showed that the results were mostly concerned with the comparison between the simulation model and the experimental data. In this paper, the finite difference method was used to solve a mass equation during drying using different kinds of boundary condition, which are equilibrium and convective boundary conditions. The results of these two models provide a comparison between the analytical and the numerical solution. The result shows a close match between the two solution curves. It is concluded that the two proposed models produce an accurate solution to describe the moisture distribution content during the drying process. This analysis indicates that we have confidence in the behaviour of moisture in the numerical simulation. This result demonstrated that a combined analytical and numerical approach prove that the system is behaving physically. Based on this assumption, the model of mass transfer was extended to include the temperature transfer, and the result shows a similar trend to those presented in the simpler case.

  6. Analytical solutions for anomalous dispersion transport

    Science.gov (United States)

    O'Malley, D.; Vesselinov, V. V.

    2014-06-01

    Groundwater flow and transport often occur in a highly heterogeneous environment (potentially heterogeneous at multiple spatial scales) and is impacted by geochemical reactions, advection, diffusion, and other pore scale processes. All these factors can give rise to large-scale anomalous dispersive behavior that can make complex model representation and prediction of plume concentrations challenging due to difficulties unraveling all the complexities associated with the governing processes, flow medium, and their parameters. An alternative is to use upscaled stochastic models of anomalous dispersion, and this is the approach used here. Within a probabilistic framework, we derive a number of analytical solutions for several anomalous dispersion models. The anomalous dispersion models are allowed to be either non-Gaussian (α-stable Lévy), correlated, or nonstationary from the Lagrangian perspective. A global sensitivity analysis is performed to gain a greater understanding of the extent to which uncertainty in the parameters associated with the anomalous behavior can be narrowed by examining concentration measurements from a network of monitoring wells and to demonstrate the computational speed of the solutions. The developed analytical solutions are encoded and available for use in the open source computational framework MADS (http://mads.lanl.gov).

  7. Application of a two energy group analytical solution to the Yalina experiment SC3A

    International Nuclear Information System (INIS)

    The SC3A experiment in the YALINA-Booster facility is described and investigated. For this investigation the very special configuration of YALINA-Booster is analyzed based on HELIOS calculations. To improve the representation to this special configuration a new analytical solution for two energy groups with two sources (central external and boundary source) has been developed starting form the Green's function solution. Very good agreement has been found for these improved analytical solutions. (author)

  8. Polynomial and Analytic Boundary Feedback Stabilization of Square Plate

    Directory of Open Access Journals (Sweden)

    Salsabil Nouira

    2009-11-01

    Full Text Available We consider a boundary feedback stabilization problem of the plateequation in a square, in the case where the geometric condition of Ammari-Tucsnak [6] is not satisfied. We prove a polynomial decay for regular initial data. Moreover, we prove an exponential stability result for some subspace of the energy space. Finally, we give a precise estimate on the analyticity of reachable functions wherewe have an exponential stability.

  9. Analytical Solutions for Sequentially Reactive Transport with Different Retardation Factors

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y; Buscheck, T A; Mansoor, K; Lu, X

    2001-08-01

    Integral transforms have been widely used for deriving analytical solutions for solute transport systems. Often, analytical solutions can only be written in closed form in frequency domains and numerical inverse-transforms have to be involved to obtain semi-analytical solutions in the time domain. For this reason, previously published closed form solutions are restricted either to a small number of species or to the same retardation assumption. In this paper, we applied the solution scheme proposed by Bauer et al. in the time domain. Using available analytical solutions of a single species transport with first-order decay without coupling with its parent species concentration as fundamental solutions, a daughter species concentration can be expressed as a linear function of those fundamental solutions. The implementation of the solution scheme is straight forward and exact analytical solutions are derived for one- and three-dimensional transport systems.

  10. Analytical Solution to the MHD Flow of Micropolar Fluid Over a Linear Stretching Sheet

    Directory of Open Access Journals (Sweden)

    Siddheshwar P.G.

    2015-05-01

    Full Text Available The flow due to a linear stretching sheet in a fluid with suspended particles, modeled as a micropolar fluid, is considered. All reported works on the problem use numerical methods of solution or a regular perturbation technique. An analytical solution is presented in the paper for the coupled non-linear differential equations with inhomogeneous boundary conditions.

  11. Analytical Solution to the MHD Flow of Micropolar Fluid Over a Linear Stretching Sheet

    OpenAIRE

    Siddheshwar P.G.; Mahabaleshwar U.S.

    2015-01-01

    The flow due to a linear stretching sheet in a fluid with suspended particles, modeled as a micropolar fluid, is considered. All reported works on the problem use numerical methods of solution or a regular perturbation technique. An analytical solution is presented in the paper for the coupled non-linear differential equations with inhomogeneous boundary conditions.

  12. Analytical Solution to the MHD Flow of Micropolar Fluid Over a Linear Stretching Sheet

    Science.gov (United States)

    Siddheshwar, P. G.; Mahabaleshwar, U. S.

    2015-05-01

    The flow due to a linear stretching sheet in a fluid with suspended particles, modeled as a micropolar fluid, is considered. All reported works on the problem use numerical methods of solution or a regular perturbation technique. An analytical solution is presented in the paper for the coupled non-linear differential equations with inhomogeneous boundary conditions.

  13. Analytical Solution of Multicompartment Solute Kinetics for Hemodialysis

    Directory of Open Access Journals (Sweden)

    Przemysław Korohoda

    2013-01-01

    Full Text Available Objective. To provide an exact solution for variable-volume multicompartment kinetic models with linear volume change, and to apply this solution to a 4-compartment diffusion-adjusted regional blood flow model for both urea and creatinine kinetics in hemodialysis. Methods. A matrix-based approach applicable to linear models encompassing any number of compartments is presented. The procedure requires the inversion of a square matrix and the computation of its eigenvalues λ, assuming they are all distinct. This novel approach bypasses the evaluation of the definite integral to solve the inhomogeneous ordinary differential equation. Results. For urea two out of four eigenvalues describing the changes of concentrations in time are about 105 times larger than the other eigenvalues indicating that the 4-compartment model essentially reduces to the 2-compartment regional blood flow model. In case of creatinine, however, the distribution of eigenvalues is more balanced (a factor of 102 between the largest and the smallest eigenvalue indicating that all four compartments contribute to creatinine kinetics in hemodialysis. Interpretation. Apart from providing an exact analytic solution for practical applications such as the identification of relevant model and treatment parameters, the matrix-based approach reveals characteristic details on model symmetry and complexity for different solutes.

  14. ANALYTIC SOLUTIONS OF SYSTEMS OF FUNCTIONAL EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    LiuXinhe

    2003-01-01

    Let r be a given positive number.Denote by D=D the closed disc in the complex plane C whose center is the origin and radius is r.For any subset K of C and any integer m ≥1,write A(Dm,K)={f|f:Dm→Kis a continuous map,and f|(Dm)*is analytic).For H∈A(Dm,C)(m≥2),f∈A(D,D)and z∈D,write ψH(f)(z)=H(z,f(z)……fm=1(x)).Suppose F,G∈A(D2n+1,C),and Hk,Kk∈A(Dk,C),k=2,……,n.In this paper,the system of functional equations {F(z,f(z),f2(ψHz(f)(z))…,fn(ψk2(g)(x))… gn(ψKn(g)(z)))=0 G(z,f(z),f2(ψH2(f)(z))…fn(ψHn(f)(z)),g(z),g2(ψk2(g)(x))…,gn(ψkn(g)(z)))=0(z∈D)is studied and some conditions for the system of equations to have a solution or a unique solution in A(D,D)×A(D,D)are given.

  15. Exact Solutions of Chemically Reactive Solute Distribution in MHD Boundary Layer Flow over a Shrinking Surface

    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

  16. ANALYTICAL SOLUTION OF GROUNDWATER FLUCTUATIONS IN ESTUARINE AQUIFER

    Institute of Scientific and Technical Information of China (English)

    CHEN Jing; ZHOU Zhi-fang; JIA Suo-bao

    2005-01-01

    As a basic factor in the environment of estuary, tidal effects in the coastal aquifer have recently attracted much attention because tidal dynamic also greatly influences the solute transport in the coastal aquifer. Previous studies on tidal dynamic of coastal aquifers have focused on the inland propagation of oceanic tides in the cross-shore direction, a configuration that is essentially one-dimensional. Two-dimensional analytical solutions for groundwater level fluctuation in recent papers are localized in presenting the effect of both oceanic tides and estuarine tides in quadrantal aquifer. A two-dimensional model of groundwater fluctuations in estuarine zone in proposed in this paper. Using complex transform, the two-dimensional flow equation subject to periodic boundary condition is changed into time-independent elliptic problem. Based on Green function method, an analytical solution for groundwater fluctuations in fan-shaped aquifer is derived. The response to of groundwater tidal loading in an estuary and ocean is discussed. The result show that its more extensive application than recent studies.

  17. Transient Solute Drag in Migrating Grain Boundaries

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; Fischer, F. D.; Liendl, M.

    2011-01-01

    Roč. 59, č. 17 (2011), s. 6556-6562. ISSN 1359-6454 R&D Projects: GA MŠk(CZ) OC10029 Institutional research plan: CEZ:AV0Z20410507 Keywords : Grain boundary diffusion * Grain boundary migration * Grain boundary segregation Subject RIV: BJ - Thermodynamics Impact factor: 3.755, year: 2011

  18. Solution of moving boundary problems with implicit boundary condition

    International Nuclear Information System (INIS)

    An algorithm that solves numerically a model for studying one dimensional moving boundary problems, with implicit boundary condition, is described. Landau's transformation is used, in order to work with a fixed number of nodes at each instant. Then, it is necessary to deal with a parabolic partial differential equation, whose diffusive and convective terms have variable coefficients. The partial differential equation is implicitly discretized, using Laasonen's scheme, always stable, instead of employing Crank-Nicholson sheme, as it has been done by Ferris and Hill. Fixed time and space steps (Δt, Δξ) are used, and the iteration is made with variable positions of the interface, i.e. varying δs until a boundary condition is satisfied. The model has the same features of the oxygen diffusion in absorbing tissue. It would be capable of estimating time variant radiation treatments of cancerous tumors. (Author)

  19. Substantive provisions of Numeral-analytical boundary elements method

    Directory of Open Access Journals (Sweden)

    V.F. Orobey

    2011-06-01

    Full Text Available Substantive propositions of the new method of design calculation, that got the name "Numeral-analytical of boundary elements method", offered by authors, are brought. A method consists of development of the fundamental system of decisions (analytically and Green functions (also analytically for every examined task.For the account of certain border terms, or terms of contact between the separate modules (the separate element of the system is so named the small system of linear algebraic equalizations, that must be decided numeral, is made.Discretisation only of border of the area occupied by an object, sharply diminishes the order of the system of resolvent equalizations; there is possibility of decline of regularity of the decided task. A method is strictly reasonable mathematically, as uses the fundamental decisions of differential equalizations, and, means, within the framework of the accepted hypotheses allows to get the exact meaning of parameters of task (efforts, moving, tensions, currents, frequencies of eigentones, critical forces of loss of stability et cetera into an area.Simplicity of logic of algorithm, good convergence of decision, high stability and small accumulation of errors at numeral operations, are marked also.

  20. Analytically-derived sensitivities in one-dimensional models of solute transport in porous media

    Science.gov (United States)

    Knopman, D.S.

    1987-01-01

    Analytically-derived sensitivities are presented for parameters in one-dimensional models of solute transport in porous media. Sensitivities were derived by direct differentiation of closed form solutions for each of the odel, and by a time integral method for two of the models. Models are based on the advection-dispersion equation and include adsorption and first-order chemical decay. Boundary conditions considered are: a constant step input of solute, constant flux input of solute, and exponentially decaying input of solute at the upstream boundary. A zero flux is assumed at the downstream boundary. Initial conditions include a constant and spatially varying distribution of solute. One model simulates the mixing of solute in an observation well from individual layers in a multilayer aquifer system. Computer programs produce output files compatible with graphics software in which sensitivities are plotted as a function of either time or space. (USGS)

  1. Analytic solutions of a class of nonlinearly dynamic systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, M-C [System Engineering Institute of Tianjin University, Tianjin, 300072 (China); Zhao, X-S; Liu, X [Tianjin University of Technology and Education, Tianjin, 300222 (China)], E-mail: mchwang123@163.com.cn, E-mail: xszhao@mail.nwpu.edu.cn, E-mail: liuxinhubei@163.com.cn

    2008-02-15

    In this paper, the homotopy perturbation method (HPM) is applied to solve a coupled system of two nonlinear differential with first-order similar model of Lotka-Volterra and a Bratus equation with a source term. The analytic approximate solutions are derived. Furthermore, the analytic approximate solutions obtained by the HPM with the exact solutions reveals that the present method works efficiently.

  2. Approximate analytic solutions to 3D unconfined groundwater flow within regional 2D models

    Science.gov (United States)

    Luther, K.; Haitjema, H. M.

    2000-04-01

    We present methods for finding approximate analytic solutions to three-dimensional (3D) unconfined steady state groundwater flow near partially penetrating and horizontal wells, and for combining those solutions with regional two-dimensional (2D) models. The 3D solutions use distributed singularities (analytic elements) to enforce boundary conditions on the phreatic surface and seepage faces at vertical wells, and to maintain fixed-head boundary conditions, obtained from the 2D model, at the perimeter of the 3D model. The approximate 3D solutions are analytic (continuous and differentiable) everywhere, including on the phreatic surface itself. While continuity of flow is satisfied exactly in the infinite 3D flow domain, water balance errors can occur across the phreatic surface.

  3. Problem of the Moving Boundary in Continuous Casting Solved by the Analytic-Numerical Method

    Directory of Open Access Journals (Sweden)

    R. Grzymkowski

    2013-01-01

    Full Text Available Mathematical modeling of thermal processes combined with the reversible phase transitions of type: solid phase – liquid phase leads to formulation of the parabolic or elliptic moving boundary problem. Solution of such defined problem requires, most often, to use some sophisticated numerical techniques and far advanced mathematical tools. The paper presents an analytic-numerical method, especially attractive from the engineer’s point of view, applied for finding the approximate solutions of the selected class of problems which can be reduced to the one-phase solidification problem of a plate with the unknown a priori, varying in time boundary of the region in which the solution is sought. Proposed method is based on the known formalism of initial expansion of a sought function, describing the field of temperature, into the power series, some coefficients of which are determined with the aid of boundary conditions, and on the approximation of a function defining the freezing front location with the broken line, parameters of which are determined numerically. The method represents a combination of the analytical and numerical techniques and seems to be an effective and relatively easy in using tool for solving problems of considered kind.

  4. Stable and chaotic solutions of the complex Ginzburg-Landau equation with periodic boundary conditions

    OpenAIRE

    Scheuer, Jacob; Malomed, Boris A.

    2001-01-01

    We study, analytically and numerically, the dynamical behavior of the solutions of the complex Ginzburg-Landau equation with diffraction but without diffusion, which governs the spatial evolution of the field in an active nonlinear laser cavity. Accordingly, the solutions are subject to periodic boundary conditions. The analysis reveals regions of stable stationary solutions in the model’s parameter space, and a wide range of oscillatory and chaotic behaviors. Close to the first bifurca...

  5. Analytical Solution for Stellar Density in Globular Clusters

    Indian Academy of Sciences (India)

    M. A. Sharaf; A. M. Sendi

    2011-09-01

    In this paper, four parameters analytical solution will be established for the stellar density function in globular clusters. The solution could be used for any arbitrary order of outward decrease of the cluster’s density.

  6. Analyticity of solutions for randomly forced two-dimensional Navier-Stokes equations

    International Nuclear Information System (INIS)

    A study is made of randomly forced two-dimensional Navier-Stokes equations with periodic boundary conditions. Under the assumption that the random forcing is analytic in the spatial variables and is a white noise in the time, it is proved that a large class of solutions, which contains all stationary solutions with finite energy, admits analytic continuation to a small complex neighbourhood of the torus. Moreover, a lower bound is obtained for the radius of analyticity in terms of the viscosity ν, and it is shown that the Kolmogorov dissipation scale can be asymptotically estimated below by ν2+δ for any δ>0

  7. Analytical Solution of Flow and Heat Transfer over a Permeable Stretching Wall in a Porous Medium

    OpenAIRE

    M. Dayyan; Seyyedi, S. M.; G. G. Domairry; M. Gorji Bandpy

    2013-01-01

    Boundary layer flow through a porous medium over a stretching porous wall has seen solved with analytical solution. It has been considered two wall boundary conditions which are power-law distribution of either wall temperature or heat flux. These are general enough to cover the isothermal and isoflux cases. In addition to momentum, both first and second laws of thermodynamics analyses of the problem are investigated. The governing equations are transformed into a system of ordinary differen...

  8. Analytical chemistry: Sweet solution to sensing

    Science.gov (United States)

    Sia, Samuel K.; Chin, Curtis D.

    2011-09-01

    Glucose meters allow rapid and quantitative measurement of blood sugar levels for diabetes sufferers worldwide. Now a new method allows this proven technology to be used to quantify a much wider range of analytes.

  9. Atomically ordered solute segregation behaviour in an oxide grain boundary

    Science.gov (United States)

    Feng, Bin; Yokoi, Tatsuya; Kumamoto, Akihito; Yoshiya, Masato; Ikuhara, Yuichi; Shibata, Naoya

    2016-01-01

    Grain boundary segregation is a critical issue in materials science because it determines the properties of individual grain boundaries and thus governs the macroscopic properties of materials. Recent progress in electron microscopy has greatly improved our understanding of grain boundary segregation phenomena down to atomistic dimensions, but solute segregation is still extremely challenging to experimentally identify at the atomic scale. Here, we report direct observations of atomic-scale yttrium solute segregation behaviours in an yttria-stabilized-zirconia grain boundary using atomic-resolution energy-dispersive X-ray spectroscopy analysis. We found that yttrium solute atoms preferentially segregate to specific atomic sites at the core of the grain boundary, forming a unique chemically-ordered structure across the grain boundary. PMID:27004614

  10. Atomically ordered solute segregation behaviour in an oxide grain boundary

    Science.gov (United States)

    Feng, Bin; Yokoi, Tatsuya; Kumamoto, Akihito; Yoshiya, Masato; Ikuhara, Yuichi; Shibata, Naoya

    2016-03-01

    Grain boundary segregation is a critical issue in materials science because it determines the properties of individual grain boundaries and thus governs the macroscopic properties of materials. Recent progress in electron microscopy has greatly improved our understanding of grain boundary segregation phenomena down to atomistic dimensions, but solute segregation is still extremely challenging to experimentally identify at the atomic scale. Here, we report direct observations of atomic-scale yttrium solute segregation behaviours in an yttria-stabilized-zirconia grain boundary using atomic-resolution energy-dispersive X-ray spectroscopy analysis. We found that yttrium solute atoms preferentially segregate to specific atomic sites at the core of the grain boundary, forming a unique chemically-ordered structure across the grain boundary.

  11. Approximate analytical solution of MHD flow of an Oldroyd 8-constant fluid in a porous medium

    Directory of Open Access Journals (Sweden)

    Faisal Salah

    2014-12-01

    Full Text Available The steady flow in an incompressible, magnetohydrodynamic (MHD Oldroyd 8-constant fluid in a porous medium with the motion of an infinite plate is investigated. Using modified Darcy’s law of an Oldroyd 8-constant fluid, the equations governing the flow are modelled. The resulting nonlinear boundary value problem is solved using the homotopy analysis method (HAM. The obtained approximate analytical solutions clearly satisfy the governing nonlinear equations and all the imposed initial and boundary conditions. The convergence of the HAM solutions for different orders of approximation is demonstrated. For the Newtonian case, the approximate analytical solution via HAM is shown to be in close agreement with the exact solution. Finally, the variations of velocity field with respect to the magnetic field, porosity and non-Newtonian fluid parameters are graphically shown and discussed.

  12. Analytical model for intergrain expansion and cleavage: random grain boundaries

    International Nuclear Information System (INIS)

    A description of rigid-body grain boundary relaxation and cleavage in tungsten is performed using a pair-wise Morse interatomic potential in real and reciprocal spaces. Cleavage energies and grain boundary dilatation of random grain boundaries were formulated and computed using atomic layer interaction energies. These values were determined using a model for a relaxed random grain boundary that consists of rigid grains on either side of the boundary plane that are allowed to float to reach the equilibrium position. Expressions are given that describe in real space the energy of interatomic interaction on random grain boundaries with twist orientation. It was shown that grain-boundary expansion and cleavage energies of the most widespread random grain boundaries are mainly determined by grain boundary atomic density

  13. Analytical solution and computer program (FAST) to estimate fluid fluxes from subsurface temperature profiles

    Science.gov (United States)

    Kurylyk, Barret L.; Irvine, Dylan J.

    2016-02-01

    This study details the derivation and application of a new analytical solution to the one-dimensional, transient conduction-advection equation that is applied to trace vertical subsurface fluid fluxes. The solution employs a flexible initial condition that allows for nonlinear temperature-depth profiles, providing a key improvement over most previous solutions. The boundary condition is composed of any number of superimposed step changes in surface temperature, and thus it accommodates intermittent warming and cooling periods due to long-term changes in climate or land cover. The solution is verified using an established numerical model of coupled groundwater flow and heat transport. A new computer program FAST (Flexible Analytical Solution using Temperature) is also presented to facilitate the inversion of this analytical solution to estimate vertical groundwater flow. The program requires surface temperature history (which can be estimated from historic climate data), subsurface thermal properties, a present-day temperature-depth profile, and reasonable initial conditions. FAST is written in the Python computing language and can be run using a free graphical user interface. Herein, we demonstrate the utility of the analytical solution and FAST using measured subsurface temperature and climate data from the Sendia Plain, Japan. Results from these illustrative examples highlight the influence of the chosen initial and boundary conditions on estimated vertical flow rates.

  14. Analytical solutions to dissolved contaminant plume evolution with source depletion during carbon dioxide storage

    Science.gov (United States)

    Yang, Yong; Liu, Yongzhong; Yu, Bo; Ding, Tian

    2016-06-01

    Volatile contaminants may migrate with carbon dioxide (CO2) injection or leakage in subsurface formations, which leads to the risk of the CO2 storage and the ecological environment. This study aims to develop an analytical model that could predict the contaminant migration process induced by CO2 storage. The analytical model with two moving boundaries is obtained through the simplification of the fully coupled model for the CO2-aqueous phase -stagnant phase displacement system. The analytical solutions are confirmed and assessed through the comparison with the numerical simulations of the fully coupled model. Then, some key variables in the analytical solutions, including the critical time, the locations of the dual moving boundaries and the advance velocity, are discussed to present the characteristics of contaminant migration in the multi-phase displacement system. The results show that these key variables are determined by four dimensionless numbers, Pe, RD, Sh and RF, which represent the effects of the convection, the dispersion, the interphase mass transfer and the retention factor of contaminant, respectively. The proposed analytical solutions could be used for tracking the migration of the injected CO2 and the contaminants in subsurface formations, and also provide an analytical tool for other solute transport in multi-phase displacement system.

  15. Series Solution for Unsteady Boundary-Layer Flows Due to Impulsively Stretching Plate

    Institute of Scientific and Technical Information of China (English)

    Seripah Awang Kechil; Ishak Hashim

    2007-01-01

    @@ The third-order nonlinear partial differential equation modelling the unsteady boundary-layer flows caused by an impulsively stretching flat plate is solved by using the Adomian decomposition method (ADM). The ADM yields analytic solution in the form of a rapidly convergent infinite series with easily computable terms. The series solution using the ADM for the unsteady flows is presented for the first time.

  16. Positive Solutions for Boundary Value Problems with Fractional Order

    Directory of Open Access Journals (Sweden)

    Mouffak Benchohra

    2013-02-01

    Full Text Available In this paper we investigate the existence of at least one, two positive solutions by using the Krasnoselskii fixed-point theorem in cones for nonlinear boundary value problem with fractional order.

  17. Positive Solutions for Higher Order Singular -Laplacian Boundary Value Problems

    Indian Academy of Sciences (India)

    Guoliang Shi; Junhong Zhang

    2008-05-01

    This paper investigates $2m-\\mathrm{th}(m≥ 2)$ order singular -Laplacian boundary value problems, and obtains the necessary and sufficient conditions for existence of positive solutions for sublinear 2-th order singular -Laplacian BVPs on closed interval.

  18. Fundamental solutions for transversely isotropic magneto-electro-elastic media and boundary integral formulation

    Institute of Scientific and Technical Information of China (English)

    丁皓江; 江爱民

    2003-01-01

    To obtain the fundamental solutions for computation of magneto-electro-elastic media by the boundary element method, the general solutions in the case of distinct eigenvalues are derived and expressed in five harmonic functions from the governing equations and the strict differential operator theorem. On the basis of these general solutions, the fundamental solution of infinite magneto-electro-elastic solid are obtained with the method of trial-and-error. Finally, the boundary integral formulation is derived and the corresponding boundary element method program is implemented to perform two numerical calculations(a column under uni-axial tension, uniform electric displacement or uniform magnetic induction, an annular plate simply-supported on outer and inner surfaces under axial loads). The numerical results agree well with the analytical ones.

  19. Analytical solutions of coupled-mode equations for microring resonators

    Indian Academy of Sciences (India)

    ZHAO C Y

    2016-06-01

    We present a study on analytical solutions of coupled-mode equations for microring resonators with an emphasis on occurrence of all-optical EIT phenomenon, obtained by using a cofactor. As concrete examples, analytical solutions for a $3 \\times 3$ linearly distributed coupler and a circularly distributed coupler are obtained. The former corresponds to a non-degenerate eigenvalue problem and the latter corresponds to a degenerate eigenvalue problem. For comparison and without loss of generality, analytical solution for a $4 \\times 4$ linearly distributed coupler is also obtained. This paper may be of interest to optical physics and integrated photonics communities.

  20. Approximate analytical solution of two-dimensional multigroup P-3 equations

    International Nuclear Information System (INIS)

    Iterative solution of multigroup spherical harmonics equations reduces, in the P-3 approximation and in two-dimensional geometry, to a problem of solving an inhomogeneous system of eight ordinary first order differential equations. With appropriate boundary conditions, these equations have to be solved for each energy group and in each iteration step. The general solution of the corresponding homogeneous system of equations is known in analytical form. The present paper shows how the right-hand side of the system can be approximated in order to derive a particular solution and thus an approximate analytical expression for the general solution of the inhomogeneous system. This combined analytical-numerical approach was shown to have certain advantages compared to the finite-difference method or the Lie-series expansion method, which have been used to solve similar problems. (orig./RW)

  1. Approximate analytical solution of two-dimensional multigroup P-3 equations

    International Nuclear Information System (INIS)

    Iterative solution of multigroup spherical harmonics equations reduces, in the P-3 approximation and in two-dimensional geometry, to a problem of solving an inhomogeneous system of eight ordinary first order differential equations. With appropriate boundary conditions, these equations have to be solved for each energy group and in each iteration step. The general solution of the corresponding homogeneous system of equations is known in analytical form. The present paper shows how the right-hand side of the system can be approximated in order to derive a particular solution and thus an approximate analytical expression for the general solution of the inhomogeneous system. This combined analytical-numerical approach was shown to have certain advantages compared to the finite-difference method or the Lie-series expansion method, which have been used to solve similar problems. (author)

  2. Analytical Solutions for the Equilibrium states of a Swollen Hydrogel Shell and an Extended Method of Matched Asymptotics

    CERN Document Server

    Dai, Hui-Hui

    2011-01-01

    A polymer network can imbibe water, forming an aggregate called hydrogel, and undergo large and inhomogeneous deformation with external mechanical constraint. Due to the large deformation, nonlinearity plays a crucial role, which also causes the mathematical difficulty for obtaining analytical solutions. Based on an existing model for equilibrium states of a swollen hydrogel with a core-shell structure, this paper seeks analytical solutions of the deformations by perturbation methods for three cases, i.e. free-swelling, nearly free-swelling and general inhomogeneous swelling. Particularly for the general inhomogeneous swelling, we introduce an extended method of matched asymptotics to construct the analytical solution of the governing nonlinear second-order variable-coefficient differential equation. The analytical solution captures the boundary layer behavior of the deformation. Also, analytical formulas for the radial and hoop stretches and stresses are obtained at the two boundary surfaces of the shell, ma...

  3. Analytical solutions of the extended Boussinesq equation

    International Nuclear Information System (INIS)

    The extended Boussinesq equation for the description of the Fermi-Pasta-Ulam problem has been studied and analyzed with the Painleve test. It has been shown that the equation does not pass the Painleve test, but the necessary condition for the existence of meromorphic solutions is satisfied

  4. Analyticity of solutions of the Korteweg-de Vries equation

    OpenAIRE

    Tarama, Shigeo

    2004-01-01

    We consider the analytic smoothing effect for the KdV equation. That is to say, if the initial data given at $t = 0$ decays very rapidly, the solution to the Cauchy problem becomes analytic with respect to the space variable for $t > 0$. In this paper we show this effect by using the inverse scattering method which transforms the KdV equation to a linear dispersive equation whose analytic smoothing effect is shown through the properties of the Airy function.

  5. Analytical r-mode solution with gravitational radiation reaction force

    CERN Document Server

    Dias, O J C; S\\'a, Paulo M.

    2005-01-01

    We present and discuss the analytical r-mode solution to the linearized hydrodynamic equations of a slowly rotating, Newtonian, barotropic, non-magnetized, perfect-fluid star in which the gravitational radiation reaction force is present.

  6. False Vacuum Transitions - Analytical Solutions and Decay Rate Values

    CERN Document Server

    Correa, R A C; da Rocha, Roldao

    2015-01-01

    In this work we show a class of oscillating configurations for the evolution of the domain walls in Euclidean space. The solutions are obtained analytically. We also find the decay rate of the false vacuum.

  7. Series solutions of boundary-layer flows in porous media with lateral mass flux

    Energy Technology Data Exchange (ETDEWEB)

    Awang Kechil, Seripah [Universiti Tekonologi MARA, Department of Mathematics, Shah Alam Selangor (Malaysia); Hashim, Ishak [Universiti Kebangsaan Malaysia, School of Mathematical Sciences, UKM Bangi Selangor (Malaysia)

    2008-08-15

    Approximate analytical solutions for free convection boundary layers on a heated vertical plate with lateral mass flux embedded in a saturated porous medium are presented using the modified Adomian decomposition method and Pade technique. Several values of the wall temperature exponent for illustrating the effects of suction/injection parameter on the flow and heat transfer are considered. This study also includes the influence of the exponent on an impermeable surface. The results obtained are comparable to the exact analytical solutions and elucidate reliability and efficiency of the technique. (orig.)

  8. New software solutions for analytical spectroscopists

    Science.gov (United States)

    Davies, Antony N.

    1999-05-01

    Analytical spectroscopists must be computer literate to effectively carry out the tasks assigned to them. This has often been resisted within organizations with insufficient funds to equip their staff properly, a lack of desire to deliver the essential training and a basic resistance amongst staff to learn the new techniques required for computer assisted analysis. In the past these problems were compounded by seriously flawed software which was being sold for spectroscopic applications. Owing to the limited market for such complex products the analytical spectroscopist often was faced with buying incomplete and unstable tools if the price was to remain reasonable. Long product lead times meant spectrometer manufacturers often ended up offering systems running under outdated and sometimes obscure operating systems. Not only did this mean special staff training for each instrument where the knowledge gained on one system could not be transferred to the neighbouring system but these spectrometers were often only capable of running in a stand-alone mode, cut-off from the rest of the laboratory environment. Fortunately a number of developments in recent years have substantially changed this depressing picture. A true multi-tasking operating system with a simple graphical user interface, Microsoft Windows NT4, has now been widely introduced into the spectroscopic computing environment which has provided a desktop operating system which has proved to be more stable and robust as well as requiring better programming techniques of software vendors. The opening up of the Internet has provided an easy way to access new tools for data handling and has forced a substantial re-think about results delivery (for example Chemical MIME types, IUPAC spectroscopic data exchange standards). Improved computing power and cheaper hardware now allows large spectroscopic data sets to be handled without too many problems. This includes the ability to carry out chemometric operations in

  9. Analytic solutions for marginal deformations in open superstring field theory

    International Nuclear Information System (INIS)

    We extend the calculable analytic approach to marginal deformations recently developed in open bosonic string field theory to open superstring field theory formulated by Berkovits. We construct analytic solutions to all orders in the deformation parameter when operator products made of the marginal operator and the associated superconformal primary field are regular. (orig.)

  10. A hybrid ICT-solution for smart meter data analytics

    DEFF Research Database (Denmark)

    Liu, Xiufeng; Nielsen, Per Sieverts

    2016-01-01

    analytics. The proposed solution offers an information integration pipeline for ingesting data from smart meters, a scalable platform for processing and mining big data sets, and a web portal for visualizing analytics results. The implemented system has a hybrid architecture of using Spark or Hive for big...

  11. Analytical solutions for the Rabi model

    CERN Document Server

    Yu, Lixian; Liang, Qifeng; Chen, Gang; Jia, Suotang

    2012-01-01

    The Rabi model that describes the fundamental interaction between a two-level system with a quantized harmonic oscillator is one of the simplest and most ubiquitous models in modern physics. However, this model has not been solved exactly because it is hard to find a second conserved quantity besides the energy. Here we present a unitary transformation to map this unsolvable Rabi model into a solvable Jaynes-Cummings-like model by choosing a proper variation parameter. As a result, the analytical energy spectrums and wavefunctions including both the ground and the excited states can be obtained easily. Moreover, these explicit results agree well with the direct numerical simulations in a wide range of the experimental parameters. In addition, based on our obtained energy spectrums, the recent experimental observation of Bloch-Siegert in the circuit quantum electrodynamics with the ultrastrong coupling can be explained perfectly. Our results have the potential application in the solid-state quantum information...

  12. Solution of Exterior Acoustic Problems by the Boundary Element Method.

    Science.gov (United States)

    Kirkup, Stephen Martin

    Available from UMI in association with The British Library. The boundary element method is described and investigated, especially in respect of its application to exterior two -dimensional Laplace problems. Both empirical and algebraic analyses (including the effects of approximation of the boundary and boundary functions and the precision of the evaluation of the discrete forms) are developed. Methods for the automatic evaluation of the discrete forms of the Laplace and Helmholtz integral operators are reviewed and extended. Boundary element methods for the solution of exterior Helmholtz problems with general (but most importantly Neumann) boundary conditions are reviewed and some are explicitly stated using a new notation. Boundary element methods based on the boundary integral equations introduced by Brakhage & Werner/ Leis/ Panich/ Kussmaul (indirect) and Burton & Miller (direct) are given prime consideration and implemented for three -dimensional problems. The influence of the choice of weighting parameter on the performance of the methods is explored and further guidance is given. The application of boundary element methods and methods based on the Rayleigh integral to acoustic radiation problems are considered. Methods for speeding up their solution via the boundary element method are developed. Library subroutines for the solution of acoustic radiation problems are described and demonstrated. Computational techniques for the problem of predicting the noise produced by a running engine are reviewed and appraised. The application of the boundary element method to low-noise engine design and in the design of noise shields is considered. The boundary element method is applied to the Ricardo crankcase simulation rig, which is an engine -like structure. A comparison of predicted and measured sound power spectra is given.

  13. Analytical Solution for the Current Distribution in Multistrand Superconducting Cables

    CERN Document Server

    Bottura, L; Fabbri, M G

    2002-01-01

    Current distribution in multistrand superconducting cables can be a major concern for stability in superconducting magnets and for field quality in particle accelerator magnets. In this paper we describe multistrand superconducting cables by means of a distributed parameters circuit model. We derive a system of partial differential equations governing current distribution in the cable and we give the analytical solution of the general system. We then specialize the general solution to the particular case of uniform cable properties. In the particular case of a two-strand cable, we show that the analytical solution presented here is identical to the one already available in the literature. For a cable made of N equal strands we give a closed form solution that to our knowledge was never presented before. We finally validate the analytical solution by comparison to numerical results in the case of a step-like spatial distribution of the magnetic field over a short Rutherford cable, both in transient and steady ...

  14. Analytical solutions to SSC coil end design

    International Nuclear Information System (INIS)

    As part of the SCC magnet effort, Fermilab will build and test a series of one meter model SSC magnets. The coils in these magnets will be constructed with several different end configurations. These end designs must satisfy both mechanical and magnetic criteria. Only the mechanical problem will be addressed. Solutions will attempt to minimize stresses and provide internal support for the cable. Different end designs will be compared in an attempt to determine which is most appropriate for the SSC dipole. The mathematics required to create each end configuration will be described. The computer aided design, programming and machine technology needed to make the parts will be reviewed. 2 refs., 10 figs

  15. On analytic continuability of the missing Cauchy datum for Helmholtz boundary problems

    OpenAIRE

    Karamehmedovic, Mirza

    2015-01-01

    We relate the domains of analytic continuation of Dirichlet and Neumann boundary data for Helmholtz problems in two or more independent variables. The domains are related à priori, locally and explicitly in terms of complex polyrectangular neighbourhoods of planar pieces of the boundary. To this end we identify and characterise a special subspace of the standard pseudodifferential operators with real-analytic symbols. The result is applicable in the estimation of the domain of analytic contin...

  16. Speciation—targets, analytical solutions and markets

    Science.gov (United States)

    Łobiński, Ryszard

    1998-02-01

    An analysis of speciation-relevant issues leads to the conclusion that, despite the rapidly increasing number of reports, the field has reached a level of virtual stagnation in terms of research originality and market perspectives. A breakthrough is in sight but requires an advanced interdisciplinary collaboration of chemists-analysts with clinicians, ecotoxicologists and nutricionists aimed at the definition of metal (metalloid)-dependent problems relevant to human health. The feedback from analytical chemists will be stimulated by a wider availability of efficient HPLC (CZE)-inductively coupled plasma mass spectrometry (ICP MS) interfaces, chromatographic software for ICP AES and MS and sensitive on-line methods for compound identification (electrospray MS/MS). The maturity of purge and trap thermal desorption techniques and capillary GC chromatography is likely to be reflected by an increasing number of commercial dedicated systems for small molecules containing Hg, Pb, Sn and metalloids. The pre-requisite of success for such systems is the integration of a sample preparation step (based on focused low-power microwave technology) into the marketed set-up.

  17. Analytic solution of simplified Cardan's shaft model

    Directory of Open Access Journals (Sweden)

    Zajíček M.

    2014-12-01

    Full Text Available Torsional oscillations and stability assessment of the homokinetic Cardan shaft with a small misalignment angle is described in this paper. The simplified mathematical model of this system leads to the linearized equation of the Mathieu's type. This equation with and without a stationary damping parameter is considered. The solution of the original differential equation is identical with those one of the Fredholm’s integral equation with degenerated kernel assembled by means of a periodic Green's function. The conditions of solvability of such problem enable the identification of the borders between stability and instability regions. These results are presented in the form of stability charts and they are verified using the Floquet theory. The correctness of oscillation results for the system with periodic stiffness is then validated by means of the Runge-Kutta integration method.

  18. Analytical determination of distillation boundaries for ternary azeotropic systems

    OpenAIRE

    Marcilla Gomis, Antonio; Reyes Labarta, Juan Antonio; Velasco, Raúl; Serrano Cayuelas, María Dolores; Olaya López, María del Mar

    2009-01-01

    A new straight forward algorithm to calculate distillation boundaries in ternary azeotropic systems has been developed. The proposed method allows, using cubic splines, the calculation of distillation trajectories and the calculation of that corresponding to the searched distillation boundaries. The algorithm is applied to 4 ternary liquid-vapour systems to test its validity.

  19. Analytical Solution of the Time Fractional Fokker-Planck Equation

    Directory of Open Access Journals (Sweden)

    Sutradhar T.

    2014-05-01

    Full Text Available A nonperturbative approximate analytic solution is derived for the time fractional Fokker-Planck (F-P equation by using Adomian’s Decomposition Method (ADM. The solution is expressed in terms of Mittag- Leffler function. The present method performs extremely well in terms of accuracy, efficiency and simplicity.

  20. AN ANALYTICAL SOLUTION FOR CALCULATING THE INITIATION OF SEDIMENT MOTION

    Institute of Scientific and Technical Information of China (English)

    Thomas LUCKNER; Ulrich ZANKE

    2007-01-01

    This paper presents an analytical solution for calculating the initiation of sediment motion and the risk of river bed movement. It thus deals with a fundamental problem in sediment transport, for which no complete analytical solution has yet been found. The analytical solution presented here is based on forces acting on a single grain in state of initiation of sediment motion. The previous procedures for calculating the initiation of sediment motion are complemented by an innovative combination of optical surface measurement technology for determining geometrical parameters and their statistical derivation as well as a novel approach for determining the turbulence effects of velocity fluctuations. This two aspects and the comparison of the solution functions presented here with the well known data and functions of different authors mainly differ the presented solution model for calculating the initiation of sediment motion from previous approaches. The defined values of required geometrical parameters are based on hydraulically laboratory tests with spheres. With this limitations the derivated solution functions permit the calculation of the effective critical transport parameters of a single grain, the calculation of averaged critical parameters for describing the state of initiation of sediment motion on the river bed, the calculation of the probability density of the effective critical velocity as well as the calculation of the risk of river bed movement. The main advantage of the presented model is the closed analytical solution from the equilibrium of forces on a single grain to the solution functions describing the initiation of sediment motion.

  1. Constructing analytic approximate solutions to the Lane–Emden equation

    International Nuclear Information System (INIS)

    We derive analytic approximations to the solutions of the Lane–Emden equation, a basic equation in Astrophysics that describes the Newtonian equilibrium structure of a self-gravitating polytropic fluid sphere. After recalling some basic results, we focus on the construction of rational approximations, discussing the limitations of previous attempts, and providing new accurate approximate solutions. - Highlights: • We make a critical survey of the literature concerning the Lane–Emden equation. • We discuss problems in the construction of accurate rational approximate solutions. • We derive new analytic approximations of interest for star and cluster dynamics

  2. Periodic solutions to nonlinear equations with oblique boundary conditions

    OpenAIRE

    Allergretto, Walter; Papini, Duccio

    2012-01-01

    We study the existence of positive periodic solutions to nonlinear elliptic and parabolic equations with oblique and dynamical boundary conditions and non-local terms. The results are obtained through fixed point theory, topological degree methods and properties of related linear elliptic problems with natural boundary conditions and possibly non-symmetric principal part. As immediate consequences, we also obtain estimates on the principal eigenvalue for non-symmetric elliptic ...

  3. An analytical solution for improved HIFU SAR estimation

    International Nuclear Information System (INIS)

    Accurate determination of the specific absorption rates (SARs) present during high intensity focused ultrasound (HIFU) experiments and treatments provides a solid physical basis for scientific comparison of results among HIFU studies and is necessary to validate and improve SAR predictive software, which will improve patient treatment planning, control and evaluation. This study develops and tests an analytical solution that significantly improves the accuracy of SAR values obtained from HIFU temperature data. SAR estimates are obtained by fitting the analytical temperature solution for a one-dimensional radial Gaussian heating pattern to the temperature versus time data following a step in applied power and evaluating the initial slope of the analytical solution. The analytical method is evaluated in multiple parametric simulations for which it consistently (except at high perfusions) yields maximum errors of less than 10% at the center of the focal zone compared with errors up to 90% and 55% for the commonly used linear method and an exponential method, respectively. For high perfusion, an extension of the analytical method estimates SAR with less than 10% error. The analytical method is validated experimentally by showing that the temperature elevations predicted using the analytical method's SAR values determined for the entire 3D focal region agree well with the experimental temperature elevations in a HIFU-heated tissue-mimicking phantom. (paper)

  4. Irreversible and reversible reactive chromatography: analytical solutions and moment analysis for rectangular pulse injections.

    Science.gov (United States)

    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. PMID:25670415

  5. Analytical Solution of Smoluchowski Equation in Harmonic Oscillator Potential

    Institute of Scientific and Technical Information of China (English)

    SUN Xiao-Jun; LU Xiao-Xia; YAN Yu-Liang; DUAN Jun-Feng; ZHANG Jing-Shang

    2005-01-01

    Non-equilibrium fission has been described by diffusion model. In order to describe the diffusion process analytically, the analytical solution of Smoluchowski equation in harmonic oscillator potential is obtained. This analytical solution is able to describe the probability distribution and the diffusive current with the variable x and t. The results indicate that the probability distribution and the diffusive current are relevant to the initial distribution shape, initial position, and the nuclear temperature T; the time to reach the quasi-stationary state is proportional to friction coefficient β, but is independent of the initial distribution status and the nuclear temperature T. The prerequisites of negative diffusive current are justified. This method provides an approach to describe the diffusion process for fissile process in complicated potentials analytically.

  6. Analytical solutions of the simplified Mathieu’s equation

    Directory of Open Access Journals (Sweden)

    Nicolae MARCOV

    2016-03-01

    Full Text Available Consider a second order differential linear periodic equation. The periodic coefficient is an approximation of the Mathieu’s coefficient. This equation is recast as a first-order homogeneous system. For this system we obtain analytical solutions in an explicit form. The first solution is a periodic function. The second solution is a sum of two functions, the first is a continuous periodic function, but the second is an oscillating function with monotone linear increasing amplitude. We give a formula to directly compute the slope of this increase, without knowing the second numeric solution. The periodic term of the second solution may be computed directly. The coefficients of fundamental matrix of the system are analytical functions.

  7. Numerical solutions of telegraph equations with the Dirichlet boundary condition

    Science.gov (United States)

    Ashyralyev, Allaberen; Turkcan, Kadriye Tuba; Koksal, Mehmet Emir

    2016-08-01

    In this study, the Cauchy problem for telegraph equations in a Hilbert space is considered. Stability estimates for the solution of this problem are presented. The third order of accuracy difference scheme is constructed for approximate solutions of the problem. Stability estimates for the solution of this difference scheme are established. As a test problem to support theoretical results, one-dimensional telegraph equation with the Dirichlet boundary condition is considered. Numerical solutions of this equation are obtained by first, second and third order of accuracy difference schemes.

  8. An analytical model for radioactive pollutant release simulation in the atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Weymar, Guilherme J.; Vilhena, Marco T.; Bodmann, Bardo E.J., E-mail: guicefetrs@gmail.com, E-mail: mtmbvilhena@gmail.com, E-mail: bejbodmann@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Buske, Daniela; Quadros, Regis, E-mail: danielabuske@gmail.com, E-mail: quadros99@gmail.com [Universidade Federal de Pelotas (UFPel), Capao do Leao, RS (Brazil). Programa de Pos-Graduacao em Modelagem Matematica

    2013-07-01

    Simulations of emission of radioactive substances in the atmosphere from the Brazilian nuclear power plant Angra 1 are a necessary tool for control and elaboration of emergency plans as a preventive action for possible accidents. In the present work we present an analytical solution for radioactive pollutant dispersion in the atmosphere, solving the time-dependent three-dimensional advection-diffusion equation. The experiment here used as a reference in the simulations consisted of the controlled releases of radioactive tritiated water vapor from the meteorological tower close to the power plant at Itaorna Beach. The wind profile was determined using experimental meteorological data and the micrometeorological parameters were calculated from empirical equations obtained in the literature. We report on a novel analytical formulation for the concentration of products of a radioactive chain released in the atmospheric boundary layer and solve the set of coupled equations for each chain radionuclide by the GILTT solution, assuming the decay of all progenitors radionuclide for each equation as source term. Further we report on numerical simulations, as an explicit but fictitious example and consider three radionuclides in the radioactive chain of Uranium 235. (author)

  9. Analytical solution for a coaxial plasma gun: Weak coupling limit

    International Nuclear Information System (INIS)

    The analytical solution of the system of coupled ODE's which describes the time evolution of an ideal (i.e., zero resistance) coaxial plasma gun operating in the snowplow mode is obtained in the weak coupling limit, i.e, when the gun is fully influenced by the driving (RLC) circuit in which it resides but the circuit is negligibly influenced by the gun. Criteria for the validity of this limit are derived and numerical examples are presented. Although others have obtained approximate, asymptotic and numerical solutions of the equations, the present analytical results seem not to have appeared previously in the literature

  10. A Hybrid Analytical-Numerical Solution to the Laminar Flow inside Biconical Ducts

    Directory of Open Access Journals (Sweden)

    Thiago Antonini Alves

    2015-10-01

    Full Text Available In this work was presented a hybrid analytical-numerical solution to hydrodynamic problem of fully developed Newtonian laminar flow inside biconical ducts employing the Generalized Integral Transform Technique (GITT. In order to facilitate the analytical treatment and the application of the boundary conditions, a Conformal Transform was used to change the domain into a more suitable coordinate system. Thereafter, the GITT was applied on the momentum equation to obtain the velocity field. Numerical results were obtained for quantities of practical interest, such as maximum and minimum velocity, Fanning friction factor, Poiseuille number, Hagenbach factor and hydrodynamic entry length.

  11. Positive Solutions for Nonlinear Differential Equations with Periodic Boundary Condition

    Directory of Open Access Journals (Sweden)

    Shengjun Li

    2012-01-01

    Full Text Available We study the existence of positive solutions for second-order nonlinear differential equations with nonseparated boundary conditions. Our nonlinearity may be singular in its dependent variable. The proof of the main result relies on a nonlinear alternative principle of Leray-Schauder. Recent results in the literature are generalized and significantly improved.

  12. Analytical and grid-free solutions to the Lighthill-Whitham-Richards traffic flow model

    KAUST Repository

    Mazaré, Pierre Emmanuel

    2011-12-01

    In this article, we propose a computational method for solving the Lighthill-Whitham-Richards (LWR) partial differential equation (PDE) semi-analytically for arbitrary piecewise-constant initial and boundary conditions, and for arbitrary concave fundamental diagrams. With these assumptions, we show that the solution to the LWR PDE at any location and time can be computed exactly and semi-analytically for a very low computational cost using the cumulative number of vehicles formulation of the problem. We implement the proposed computational method on a representative traffic flow scenario to illustrate the exactness of the analytical solution. We also show that the proposed scheme can handle more complex scenarios including traffic lights or moving bottlenecks. The computational cost of the method is very favorable, and is compared with existing algorithms. A toolbox implementation available for public download is briefly described, and posted at http://traffic.berkeley.edu/project/downloads/lwrsolver. © 2011 Elsevier Ltd.

  13. Comparison of Web Analytics : Hosted Solutions vs Server-side Analytics

    OpenAIRE

    Mutai, Dominic

    2015-01-01

    The ratability of websites allows the aggregation of detailed data about the behavior and characteristics of website visitors. This thesis examines the value of different web metrics based on the analytics tools used and the behavior of website visitors. The objective is to test and identify key metrics and discuss how they compare between hosted solutions and server-side analytics. The value of the web metrics is evaluated by examining the relationships of the metrics to website conversions....

  14. Analytical solution to one-dimensional consolidation in unsaturated soils under sinusoidal cyclic loading

    Institute of Scientific and Technical Information of China (English)

    冯君; 巫锡勇; 朱宝龙; 杨期祥

    2015-01-01

    An analytical solution was presented to the unsaturated soil with a finite thickness under confinement in the lateral direction and sinusoidal cyclic loading in the vertical direction based on Fredlund’s one-dimensional consolidation equation for unsaturated soil. The transfer relationship between the state vectors at the top surface and any depth was gained by applying the Laplace transform and Cayley−Hamilton mathematical methods to the governing equations of water and air, Darcy’s law and Fick’s law. The excess pore-air and pore-water pressures and settlement in the Laplace-transformed domain were obtained by using the Laplace transform with the initial and boundary conditions. The analytical solutions of the excess pore-air and pore-water pressures at any depth and settlement were obtained in the time domain by performing the inverse Laplace transforms. A typical example illustrates the consolidation characteristics of unsaturated soil under sinusoidal loading from analytical results. Finally, comparisons between the analytical solutions and results of the numerical method indicate that the analytical solution is correct.

  15. Analytic solution for the propagation velocity in superconducting composities

    International Nuclear Information System (INIS)

    The propagation velocity of normal zones in composite superconductors has been calculated analytically for the case of constant thermophysical properties, including the effects of current sharing. The solution is compared with that of a more elementary theory in which current sharing is neglected, i.e., in which there is a sharp transition from the superconducting to the normal state. The solution is also compared with experiment. This comparison demonstrates the important influence of transient heat transfer on the propagation velocity

  16. Efficient analytical solutions for heated, pressurized multi-layered cylinders

    OpenAIRE

    2013-01-01

    Two independent sets of analytical solutions, one based on matrix inversion and one based on iteration, are derived for the displacement field and corresponding stress state in multi-layer cylinders subjected to pressure and thermal loading. Solutions are developed for cylinders that are axially free with no friction between layers (plane stress), for cylinders that are fully restrained axially (plane strain) and for axially loaded and spring-mounted cylinders, assuming that the combined two-...

  17. On analytic continuability of the missing Cauchy datum for Helmholtz boundary problems

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza

    2015-01-01

    We relate the domains of analytic continuation of Dirichlet and Neumann boundary data for Helmholtz problems in two or more independent variables. The domains are related à priori, locally and explicitly in terms of complex polyrectangular neighbourhoods of planar pieces of the boundary. To this...

  18. Horses for courses: analytical tools to explore planetary boundaries

    Science.gov (United States)

    van Vuuren, D. P.; Lucas, P. L.; Häyhä, T.; Cornell, S. E.; Stafford-Smith, M.

    2015-09-01

    There is a need for further integrated research on developing a set of sustainable development objectives, based on the proposed framework of planetary boundaries indicators. The relevant research questions are divided in this paper into four key categories, related to the underlying processes and selection of key indicators, understanding the impacts of different exposure levels and influence of connections between different types of impacts, a better understanding of different response strategies and the available options to implement changes. Clearly, different categories of scientific disciplines and associated models exist that can contribute to the necessary analysis, noting that the distinctions between them are fuzzy. In the paper, we both indicate how different models relate to the four categories of questions but also how further insights can be obtained by connecting the different disciplines (without necessarily fully integrating them). Research on integration can support planetary boundary quantification in a credible way, linking human drivers and social and biophysical impacts.

  19. Analytical Loss Factors in Approximation of the Leontovich Boundary Conditions

    CERN Document Server

    Baturin, S S

    2014-01-01

    Recently the new method of the Cherenkov fields and loss factors of a point-like electron bunch passing through longitudinally homogeneous structures lined with arbitrary slowdown layers was proposed. It was shown that the Cherenkov loss factor of the short bunch does not depend on the waveguide system material and is a constant for any given transverse dimensions and cross-section shapes of the waveguides. It was shown that with the proposed approach one can use a relatively simple method for the calculation of the total loss factor using an integral relation based on the cylindrical slowdown waveguide model. With this paper, we demonstrate that the same integral relation that we call relativistic Gauss theorem can be applied in case impedance boundary conditions (IBC) also known as Leontovich boundary conditions.

  20. General analytical shakedown solution for structures with kinematic hardening materials

    Science.gov (United States)

    Guo, Baofeng; Zou, Zongyuan; Jin, Miao

    2016-04-01

    The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems: a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

  1. Analytic Solutions for Tachyon Condensation with General Projectors

    CERN Document Server

    Okawa, Y; Zwiebach, B; Okawa, Yuji; Rastelli, Leonardo; Zwiebach, Barton

    2006-01-01

    The tachyon vacuum solution of Schnabl is based on the wedge states, which close under the star product and interpolate between the identity state and the sliver projector. We use reparameterizations to solve the long-standing problem of finding an analogous family of states for arbitrary projectors and to construct analytic solutions based on them. The solutions simplify for special projectors and allow explicit calculations in the level expansion. We test the solutions in detail for a one-parameter family of special projectors that includes the sliver and the butterfly. Reparameterizations further allow a one-parameter deformation of the solution for a given projector, and in a certain limit the solution takes the form of an operator insertion on the projector. We discuss implications of our work for vacuum string field theory.

  2. Analytic solutions for tachyon condensation with general projectors

    Energy Technology Data Exchange (ETDEWEB)

    Okawa, Y. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Rastelli, L. [C.N. Yang Institute for Theoretical Physics, Stony Brook, NY (United States); Zwiebach, B. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Center for Theoretical Physics

    2006-11-15

    The tachyon vacuum solution of Schnabl is based on the wedge states, which close under the star product and interpolate between the identity state and the sliver projector. We use reparameterizations to solve the long-standing problem of finding an analogous family of states for arbitrary projectors and to construct analytic solutions based on them. The solutions simplify for special projectors and allow explicit calculations in the level expansion. We test the solutions in detail for a one-parameter family of special projectors that includes the sliver and the butterfly. Reparameterizations further allow a one-parameter deformation of the solution for a given projector, and in a certain limit the solution takes the form of an operator insertion on the projector. We discuss implications of our work for vacuum string field theory. (orig.)

  3. Modelling stellar jets with magnetospheres using as initial states analytical MHD solutions

    CERN Document Server

    Todorov, P; Cayatte, V; Sauty, C; Lima, J J G; Tsinganos, K

    2016-01-01

    In this paper we focus on the construction of stellar outflow models emerging from a polar coronal hole-type region surrounded by a magnetosphere in the equatorial regions during phases of quiescent accretion. The models are based on initial analytical solutions. We adopt a meridionally self-similar solution of the time-independent and axisymmetric MHD equations which describes effectively a jet originating from the corona of a star. We modify appropriately this solution in order to incorporate a physically consistent stellar magnetosphere. We find that the closed fieldline region may exhibit different behaviour depending on the associated boundary conditions and the distribution of the heat flux. However, the stellar jet in all final equilibrium states is very similar to the analytical one prescribed in the initial conditions. When the initial net heat flux is maintained, the magnetosphere takes the form of a dynamical helmet streamer with a quasi steady state slow magnetospheric wind. With no heat flux, a s...

  4. MATHEMATIC MODEL AND ANALYTIC SOLUTION FOR CYLINDER SUBJECT TO UNEVEN PRESSURES

    Institute of Scientific and Technical Information of China (English)

    LIU Wen

    2006-01-01

    According to the inverse solution of elasticity mechanics, a stress function is constructed which meets the space biharmonic equation, this stress functions is about cubic function pressure on the inner and outer surfaces of cylinder. When borderline condition that is predigested according to the Saint-Venant's theory is joined, an equation suit is constructed which meets both the biharmonic equations and the boundary conditions. Furthermore, its analytic solution is deduced with Matlab.When this theory is applied to hydraulic bulging rollers, the experimental results inosculate with the theoretic calculation. Simultaneously, the limit along the axis invariable direction is given and the model building of hollow cylinder and for the analytic solution of hollow cylinder with randomly uneven pressure.

  5. On numerical-analytic techniques for boundary value problems

    Czech Academy of Sciences Publication Activity Database

    Rontó, András; Rontó, M.; Shchobak, N.

    2012-01-01

    Roč. 12, č. 3 (2012), s. 5-10. ISSN 1335-8243 Institutional support: RVO:67985840 Keywords : numerical-analytic method * periodic successive approximations * Lyapunov-Schmidt method Subject RIV: BA - General Mathematics http://www.degruyter.com/view/j/aeei.2012.12.issue-3/v10198-012-0035-1/v10198-012-0035-1.xml?format=INT

  6. A three-dimensional analytical solution for radioactive contaminant dispersion in the atmosphere

    International Nuclear Information System (INIS)

    In this work, we report an analytical solution for steady-state three-dimensional advection-diffusion equation for simulation of radioactive pollutant in atmosphere considering a vertically inhomogeneous Planetary Boundary Layer. The main idea relies in solution of the steady-state three-dimensional advection-diffusion equation by the combined ADMM and GILTT techniques. We also report numerical simulation assuming power wind profile and we compare with the ones achieved by the GILTT method with Gaussian in y-direction as well experimental data. (author)

  7. An analytical solution for the electrical properties of a Radio Frequency Quadrupole (RFQ) with simple vanes

    Science.gov (United States)

    Lancaster, H.

    1982-02-01

    Although the SUPERFISH program is used for calculating the design parameters of an radio frequency quadrupole (RFQ) structure with complex vanes, an analytical solution for electrical properties of an RFQ with simple vanes provides insight into the parametric behavior of these more complicated resonators. The fields in an inclined plane wave guide with proper boundary conditions match those in one quadrant of an RFQ. The principle of duality is used to exploit the solutions to a radial transmission line in solving the field equations. Calculated are the frequency equation, frequency sensitivity factors (5), electric field (E), magnetic field (H), stored energy (U), power dissipation (P), and quality factor (Q).

  8. Semi-Analytical Solution of Functionally Graded Circular Short Hollow Cylinder Subject to Transient Thermal Loading

    Directory of Open Access Journals (Sweden)

    Eskandari Jam Jafar

    2014-12-01

    Full Text Available In this paper, by using a semi-analytical solution based on multi-layered approach, the authors present the solutions of temperature, displacements, and transient thermal stresses in functionally graded circular hollow cylinders subjected to transient thermal boundary conditions. The cylinder has finite length and is subjected to axisymmetric thermal loads. It is assumed that the functionally graded circular hollow cylinder is composed of N fictitious layers and the properties of each layer are assumed to be homogeneous and isotropic. Time variations of the temperature, displacements, and stresses are obtained by employing series solving method for ordinary differential equation, Laplace transform techniques and a numerical Laplace inversion.

  9. Mathematical Model of Suspension Filtering and Its Analytical Solution

    Directory of Open Access Journals (Sweden)

    Normahmad Ravshanov

    2013-01-01

    Full Text Available The work develops mathematical model and computing algorithm to analyze, project and identify the basic parameters of filter units operation and their variation range. On their basis, numerical analytic solution of the problem of ionized liquid solutions filtering was obtained. Computing experiments, resulting in graphic format were presented. Analysis of calculation results enables to determine the optimum modes of filter units operation, used in liquid ionized solutions filtration technology, in food preparation, in drug production and for drinking water purification. Selection of the most suitable parameters contributes to the improvement of economic and technologic efficiency of production and filter units operability.

  10. The big bang and inflation united by an analytic solution

    International Nuclear Information System (INIS)

    Exact analytic solutions for a class of scalar-tensor gravity theories with a hyperbolic scalar potential are presented. Using an exact solution we have successfully constructed a model of inflation that produces the spectral index, the running of the spectral index, and the amplitude of scalar perturbations within the constraints given by the WMAP 7 years data. The model simultaneously describes the big bang and inflation connected by a specific time delay between them so that these two events are regarded as dependent on each other. In solving the Friedmann equations, we have utilized an essential Weyl symmetry of our theory in 3+1 dimensions which is a predicted remaining symmetry of 2T-physics field theory in 4+2 dimensions. This led to a new method of obtaining analytic solutions in the 1T field theory which could in principle be used to solve more complicated theories with more scalar fields. Some additional distinguishing properties of the solution includes the fact that there are early periods of time when the slow-roll approximation is not valid. Furthermore, the inflaton does not decrease monotonically with time; rather, it oscillates around the potential minimum while settling down, unlike the slow-roll approximation. While the model we used for illustration purposes is realistic in most respects, it lacks a mechanism for stopping inflation. The technique of obtaining analytic solutions opens a new window for studying inflation, and other applications, more precisely than using approximations.

  11. Exact Analytical Solution of Alfven Waves in Nonuniform Plasmas

    International Nuclear Information System (INIS)

    Full text: The propagation of Alfven waves in non-uniform plasmas is described through linear second-order differential equations, governing the total pressure and radial plasma velocity. In general, these two differential equations only admit numerical solutions, whose behavior is very much complicated especially near resonance surfaces which encompass essential degeneracies. It is well-known that most existing analytical methods, including the famous Wentzel-Karmers-Brillouin (WKB) approximation fail near such singularities. In this paper, a power analytical method, which is recently developed and named the Differential Transfer Matrix Method (DTMM), is applied to find a rigorously exact solution to the problem of interest. We also present an approximate solution based on the Airy functions. (author)

  12. Analytical Determination of the Boundaries of Transition Natural Zones (Ecotones

    Directory of Open Access Journals (Sweden)

    Rulev Aleksandr Sergeevich

    2015-04-01

    Full Text Available The morphological units that are part of the catena, are recognized in accordance with the response to the geomorphological and soil processes. The spatial relationship is the main unit between them. In this regard, the landscape patterns acquire a cascade type, and their main link becomes the zonal catena, which has specific stable features, reflecting the dependence of the complex of natural conditions and processes of latitude. However, clear-cut boundaries do not exist – they have spatial and temporal displacement, associated with the cyclical nature of the global climatic processes. The landscapes in these transition zones (ecotones a priori can be considered unstable. The detection of ecotones boundaries provides the opportunity to divide natural zones to potentially stable and potentially unstable parts for planning measures on preventing the degradation of landscapes localized in them. The latitude of the ecotones localization can be determined through the connection of the radiation heat flux on land (R with the normalized geographical latitude of the subboreal belt (x, which is described by the equation of the energy balance, expressed in the logistic function R = А / [1 + 0,72 exp(4,25 – Bx] + C.

  13. Horses for courses: analytical tools to explore planetary boundaries

    Science.gov (United States)

    van Vuuren, Detlef P.; Lucas, Paul L.; Häyhä, Tiina; Cornell, Sarah E.; Stafford-Smith, Mark

    2016-03-01

    There is a need for more integrated research on sustainable development and global environmental change. In this paper, we focus on the planetary boundaries framework to provide a systematic categorization of key research questions in relation to avoiding severe global environmental degradation. The four categories of key questions are those that relate to (1) the underlying processes and selection of key indicators for planetary boundaries, (2) understanding the impacts of environmental pressure and connections between different types of impacts, (3) better understanding of different response strategies to avoid further degradation, and (4) the available instruments to implement such strategies. Clearly, different categories of scientific disciplines and associated model types exist that can accommodate answering these questions. We identify the strength and weaknesses of different research areas in relation to the question categories, focusing specifically on different types of models. We discuss that more interdisciplinary research is need to increase our understanding by better linking human drivers and social and biophysical impacts. This requires better collaboration between relevant disciplines (associated with the model types), either by exchanging information or by fully linking or integrating them. As fully integrated models can become too complex, the appropriate type of model (the racehorse) should be applied for answering the target research question (the race course).

  14. A semi-analytical solution for slug tests in an unconfined aquifer considering unsaturated flow

    Science.gov (United States)

    Sun, Hongbing

    2016-01-01

    A semi-analytical solution considering the vertical unsaturated flow is developed for groundwater flow in response to a slug test in an unconfined aquifer in Laplace space. The new solution incorporates the effects of partial penetrating, anisotropy, vertical unsaturated flow, and a moving water table boundary. Compared to the Kansas Geological Survey (KGS) model, the new solution can significantly improve the fittings of the modeled to the measured hydraulic heads at the late stage of slug tests in an unconfined aquifer, particularly when the slug well has a partially submerged screen and moisture drainage above the water table is significant. The radial hydraulic conductivities estimated with the new solution are comparable to those from the KGS, Bouwer and Rice, and Hvorslev methods. In addition, the new solution also can be used to examine the vertical conductivity, specific storage, specific yield, and the moisture retention parameters in an unconfined aquifer based on slug test data.

  15. Analytical and Numerical Modeling of Plasma Flow Around a Circular Boundary

    Science.gov (United States)

    Scott, Roger B.

    2016-05-01

    The flow of plasma around a circular boundary is a topic of great importance for solar physics, in which individual flux tubes are often treated as discrete elements that interact with their environment through the forces exerted across their surfaces. This scenario has been suggested by McKenzie (2000) and later refined by Savage et al. (2012) as an explanation for the dark lanes that commonly form in supra-arcade fan structures, i.e. SADs. Here we present a rigorous model in which a retracting flux tube serves as an interior boundary for the surrounding magnetic field, with the associated plasma forced to flow around it. Through a zero-β analytical solution we show that under certain circumstances these flows lead to shocks that can extend far out into the unreconnected field, altering the plasma properties in the affected region. We then employ a numerical simulation that relaxes the low-β assumption and we find that the collimated shocks described in our previous study are recovered for plasma β in the range of 0 energy of the fluid exceeds the internal energy of both the fluid and the magnetic field, thereby leading to the formation of unconfined, fast-mode magnetohydrodynamic shocks, even in the limit of small β.

  16. Analytical Solution of Flow and Heat Transfer over a Permeable Stretching Wall in a Porous Medium

    Directory of Open Access Journals (Sweden)

    M. Dayyan

    2013-01-01

    Full Text Available Boundary layer flow through a porous medium over a stretching porous wall has seen solved with analytical solution. It has been considered two wall boundary conditions which are power-law distribution of either wall temperature or heat flux. These are general enough to cover the isothermal and isoflux cases. In addition to momentum, both first and second laws of thermodynamics analyses of the problem are investigated. The governing equations are transformed into a system of ordinary differential equations. The transformed ordinary equations are solved analytically using homotopy analysis method. A comprehensive parametric study is presented, and it is shown that the rate of heat transfer increases with Reynolds number, Prandtl number, and suction to the surface.

  17. Solution of Boundary-Value Problems using Kantorovich Method

    Science.gov (United States)

    Gusev, A. A.; Hai, L. L.; Chuluunbaatar, O.; Vinitsky, S. I.; Derbov, V. L.

    2016-02-01

    We propose a computational scheme for solving the eigenvalue problem for an elliptic differential equation in a two-dimensional domain with Dirichlet boundary conditions. The solution is sought in the form of Kantorovich expansion over the basis functions of one of the independent variables with the second variable treated as a parameter. The basis functions are calculated as solutions of the parametric eigenvalue problem for an ordinary second-order differential equation. As a result, the initial problem is reduced to a boundary-value problem for a set of self-adjoint second-order differential equations for functions of the second independent variable. The discrete formulation of the problem is implemented using the finite element method with Hermite interpolation polynomials. The effciency of the calculation scheme is shown by benchmark calculations for a square membrane with a degenerate spectrum.

  18. Solution of Boundary-Value Problems using Kantorovich Method

    Directory of Open Access Journals (Sweden)

    Gusev A.A.

    2016-01-01

    Full Text Available We propose a computational scheme for solving the eigenvalue problem for an elliptic differential equation in a two-dimensional domain with Dirichlet boundary conditions. The solution is sought in the form of Kantorovich expansion over the basis functions of one of the independent variables with the second variable treated as a parameter. The basis functions are calculated as solutions of the parametric eigenvalue problem for an ordinary second-order differential equation. As a result, the initial problem is reduced to a boundary-value problem for a set of self-adjoint second-order differential equations for functions of the second independent variable. The discrete formulation of the problem is implemented using the finite element method with Hermite interpolation polynomials. The effciency of the calculation scheme is shown by benchmark calculations for a square membrane with a degenerate spectrum.

  19. Solute interaction in grain boundary segregation and cohesion

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel

    Zurich : Trans Tech Publications, 2014 - (Šandera, P.), s. 389-392 ISBN 978-3-03785-934-6. ISSN 1013-9826. - (Key Engineering Materials. 592-593). [International Conference on Materials Structure and Micromechanics of Fracture /7./. Brno (CZ), 01.07.2013-03.07.2013] R&D Projects: GA ČR GAP108/12/0144 Institutional support: RVO:68378271 Keywords : interfacial segregation * grain boundary embrittlemenmt * solute interaction modeling Subject RIV: BM - Solid Matter Physics ; Magnetism

  20. Mathematic Model and Analytic Solution for a Cylinder Subject to Exponential Function

    Institute of Scientific and Technical Information of China (English)

    LIU Wen; SHAN Rui

    2009-01-01

    Hollow cylinders are widely used in spacecraft, rockets, weapons, metallurgy, materials, and mechanical manufacturing industries, and so on, hydraulic bulging roll cylinder and hydraulic press work all belong to hollow cylinders. However, up till now, the solution of the cylinder subjected to the pressures in the three-dimensional space is still at the stage of the analytical solution to the normal pressure or the approximate solution to the variable pressure by numerical method. The analytical solution to the variable pressure of the cylinder has not yet made any breakthrough in theory and can not meet accurate theoretical analysis and calculation requirements of the cylindrical in Engineering. In view of their importance, the precision calculation and theoretical analysis are required to investigate on engineering. A stress function which meets both the biharmonic equations and boundary conditions is constructed in the three-dimensional space. Furthermore, the analytic solution of a hollow cylinder subjected to exponential function distributed variable pressure on its inner and outer surfaces is deduced. By controlling the pressure subject to exponential function distributed variable pressure in the hydraulic bulging roller without any rolling load, using a static tester to record the strain supported hydraulic bulging roll, and comparing with the theoretical calculation, the experimental test result has a higher degree of agreement with the theoretical calculation. Simultaneously, the famous Lamè solution can be deduced when given the unlimited length of cylinder along the axis. The analytic solution paves the way for the mathematic building and solution of hollow cylinder with randomly uneven pressure.

  1. Analytical solutions for flow of horizontal well in compressible, three-dimensional unconsolidated formations

    International Nuclear Information System (INIS)

    A novel mathematical model for single-phase fluid flow from unconsolidated formations to a horizontal well with the consideration of stress-sensitive permeability is presented. The model assumes the formation permeability is an exponential function of the pore pressure. Using a perturbation technique, the model is solved for either constant pressure or constant flux or infinite lateral boundary conditions with closed top and bottom boundaries. Through Laplace transformation, finite Fourier transformation and numerical inversion methods, the solutions are obtained and the pressure response curves are analyzed. The agreement between the analytical solutions in this paper and the numerical results from commercial software (Saphir) is excellent, which manifests the accuracy of the results derived in this paper. (paper)

  2. Phononic heat transport in the transient regime: An analytic solution

    Science.gov (United States)

    Tuovinen, Riku; Säkkinen, Niko; Karlsson, Daniel; Stefanucci, Gianluca; van Leeuwen, Robert

    2016-06-01

    We investigate the time-resolved quantum transport properties of phonons in arbitrary harmonic systems connected to phonon baths at different temperatures. We obtain a closed analytic expression of the time-dependent one-particle reduced density matrix by explicitly solving the equations of motion for the nonequilibrium Green's function. This is achieved through a well-controlled approximation of the frequency-dependent bath self-energy. Our result allows for exploring transient oscillations and relaxation times of local heat currents, and correctly reduces to an earlier known result in the steady-state limit. We apply the formalism to atomic chains, and benchmark the validity of the approximation against full numerical solutions of the bosonic Kadanoff-Baym equations for the Green's function. We find good agreement between the analytic and numerical solutions for weak contacts and baths with a wide energy dispersion. We further analyze relaxation times from low to high temperature gradients.

  3. Analytical representation of a black hole puncture solution

    International Nuclear Information System (INIS)

    The 'moving-puncture' technique has led to dramatic advancements in the numerical simulations of binary black holes. Hannam et al. have recently demonstrated that, for suitable gauge conditions commonly employed in moving-puncture simulations, the evolution of a single black hole leads to a well-known, time-independent, maximal slicing of Schwarzschild spacetime. They construct the corresponding solution in isotropic coordinates numerically and demonstrate its usefulness, for example, for testing and calibrating numerical codes that employ moving-puncture techniques. In this brief report we point out that this solution can also be constructed analytically, making it even more useful as a test case for numerical codes

  4. Barrierless Electronic Relaxation in Solution: An Analytically Solvable Model

    CERN Document Server

    Chakraborty, Aniruddha

    2013-01-01

    We propose an analytical method for understanding the problem of electronic relaxation in solution, modeled by a particle undergoing diffusive motion under the influence of two potentials. The coupling between the two potentials is assumed to be represented by a Dirac Delta function. The diffusive motion in this paper is described by the Smoluchowskii equation. Our solution requires the knowledge of the Laplace transform of the Green's function for the motion in both the uncoupled potentials. Our model is more general than all the earlier models, because we are the first one to consider the effect of ground state potential energy surface explicitly.

  5. An Analytical Method of Auxiliary Sources Solution for Plane Wave Scattering by Impedance Cylinders

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    Analytical Method of Auxiliary Sources solutions for plane wave scattering by circular impedance cylinders are derived by transformation of the exact eigenfunction series solutions employing the Hankel function wave transformation. The analytical Method of Auxiliary Sources solution thus obtained...

  6. Analytical Analysis and Numerical Solution of Two Flavours Skyrmion

    CERN Document Server

    Hadi, Miftachul; Hermawanto, Denny

    2010-01-01

    Two flavours Skyrmion will be analyzed analytically, in case of static and rotational Skyrme equations. Numerical solution of a nonlinear scalar field equation, i.e. the Skyrme equation, will be worked with finite difference method. This article is a more comprehensive version of \\textit{SU(2) Skyrme Model for Hadron} which have been published at Journal of Theoretical and Computational Studies, Volume \\textbf{3} (2004) 0407.

  7. Analytic solution of certain second-order functional differential equation

    Directory of Open Access Journals (Sweden)

    Theeradach Kaewong

    2006-09-01

    Full Text Available We consider the existence of analytic solutions of a certain class of iterative second-order functional differential equation of the form x″(x[r](z=c0z2+c1(x(z2+(c2x[2](z2+⋯+cm(x[m](z2, m,r≥0.

  8. Semi-analytical solution for soliton propagation in colloidal suspension

    Directory of Open Access Journals (Sweden)

    Senthilkumar Selvaraj

    2013-04-01

    Full Text Available We consider the propagation of soliton in colloidal nano-suspension. We derive the semi analytical solution for soliton propagation in colloidal nano-suspensions for both one and two spatial dimensions using variational method. This Variational method uses both Averaged Lagrangian and suitable trial functions. Finally we analyse about Rayleigh scattering loss in the soliton propagation through the colloidal nano-suspensions.

  9. Approximate analytical solutions of the baby Skyrme model

    OpenAIRE

    Ioannidou, T. A.; Kopeliovich, V. B.; Zakrzewski, W. J.

    2002-01-01

    In present paper we show that many properties of the baby skyrmions, which have been determined numerically, can be understood in terms of an analytic approximation. In particular, we show that this approximation captures properties of the multiskyrmion solutions (derived numerically) such as their stability towards decay into various channels, and that it is more accurate for the "new baby Skyrme model" which describes anisotropic physical systems in terms of multiskyrmion fields with axial ...

  10. Analytical Solutions of the Balance Equation for the Scalar Variance in One-Dimensional Turbulent Flows under Stationary Conditions

    Directory of Open Access Journals (Sweden)

    Andrea Amicarelli

    2015-01-01

    Full Text Available This study presents 1D analytical solutions for the ensemble variance of reactive scalars in one-dimensional turbulent flows, in case of stationary conditions, homogeneous mean scalar gradient and turbulence, Dirichlet boundary conditions, and first order kinetics reactions. Simplified solutions and sensitivity analysis are also discussed. These solutions represent both analytical tools for preliminary estimations of the concentration variance and upwind spatial reconstruction schemes for CFD (Computational Fluid Dynamics—RANS (Reynolds-Averaged Navier-Stokes codes, which estimate the turbulent fluctuations of reactive scalars.

  11. A new analytical solution to axisymmetric Blot's consolidation of a finite soil layer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new analytical method is presented to study the axisymmetric Blot's consolidation of a finite soil layer. Starting from the governing equations of axisymmetric Blot's consolidation, and based on the property of Laplace transform, the relation of basic variables for a point of a finite soil layer is established between the ground surface (z= 0) and the depth z in the Laplace and Hankel transform domains. Combined with the boundary conditions of the finite soil layer, the analytical solution of any point in the transform domain can be obtained. The actual solution in the physical domain can be obtained by inverse Laplace and Hankel transforms. A numerical analysis for the axisymmetric consolidation of a finite soil layer is carried out.

  12. Development of CAD implementing the algorithm of boundary elements’ numerical analytical method

    Directory of Open Access Journals (Sweden)

    Yulia V. Korniyenko

    2015-03-01

    Full Text Available Up to recent days the algorithms for numerical-analytical boundary elements method had been implemented with programs written in MATLAB environment language. Each program had a local character, i.e. used to solve a particular problem: calculation of beam, frame, arch, etc. Constructing matrices in these programs was carried out “manually” therefore being time-consuming. The research was purposed onto a reasoned choice of programming language for new CAD development, allows to implement algorithm of numerical analytical boundary elements method and to create visualization tools for initial objects and calculation results. Research conducted shows that among wide variety of programming languages the most efficient one for CAD development, employing the numerical analytical boundary elements method algorithm, is the Java language. This language provides tools not only for development of calculating CAD part, but also to build the graphic interface for geometrical models construction and calculated results interpretation.

  13. Numerical solutions of multi-dimensional solidification/melting problems by the dual reciprocity boundary element method

    International Nuclear Information System (INIS)

    This paper presents an effective and simple procedure for the simulation of the motion of the solid-liquid interfacial boundary and the transient temperature field during phase change process. To accomplish this purpose, an iterative implicit solution algorithm has been developed by employing the dual reciprocity boundary element method. The dual reciprocity boundary element approach provided in this paper is much simpler than the usual boundary element method applying a reciprocity principle and an available technique for dealing with domain integral of boundary element formulation simultaneously. The effectiveness of the present analysis method have been illustrated through comparisons of the calculation results of an example with its semi-analytical or other numerical solutions where available

  14. Numerical solutions of multi-dimensional solidification/melting problems by the dual reciprocity boundary element method

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Jong Chull; Shin, Won Ky [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of)

    1997-12-31

    This paper presents an effective and simple procedure for the simulation of the motion of the solid-liquid interfacial boundary and the transient temperature field during phase change process. To accomplish this purpose, an iterative implicit solution algorithm has been developed by employing the dual reciprocity boundary element method. The dual reciprocity boundary element approach provided in this paper is much simpler than the usual boundary element method applying a reciprocity principle and an available technique for dealing with domain integral of boundary element formulation simultaneously. The effectiveness of the present analysis method have been illustrated through comparisons of the calculation results of an example with its semi-analytical or other numerical solutions where available. 22 refs., 3 figs. (Author)

  15. Analytical model for temperature distribution of an end diode-pumped laser slab with Robin boundary conditions by Green’s function method

    Science.gov (United States)

    Moghtader Dindarlu, M. H.; Kavosh Tehrani, M.; Saghafifar, H.; Maleki, A.

    2016-05-01

    In this paper, an analytical model is introduced for temperature distribution of an end diode-pumped laser slab by Green’s function method. To solve the heat equation, Robin boundary conditions are considered because four lateral faces of the slab are cooled by water. An analytical model is extracted for single and dual end-pumping configuration. For an example, the 2D and 3D temperature distributions are plotted and our analytical model is validated by numerical solution based on the finite element method (FEM). The results show that our model has very good agreement with numerical solution. Furthermore, dependence of the temperature distribution on absorbed pump power is shown.

  16. Analytical solution for multilayer plates using general layerwise plate theory

    Directory of Open Access Journals (Sweden)

    Vuksanović Đorđe M.

    2005-01-01

    Full Text Available This paper deals with closed-form solution for static analysis of simply supported composite plate, based on generalized laminate plate theory (GLPT. The mathematical model assumes piece-wise linear variation of in-plane displacement components and a constant transverse displacement through the thickness. It also include discrete transverse shear effect into the assumed displacement field, thus providing accurate prediction of transverse shear stresses. Namely, transverse stresses satisfy Hook's law, 3D equilibrium equations and traction free boundary conditions. With assumed displacement field, linear strain-displacement relation, and constitutive equations of the lamina, equilibrium equations are derived using principle of virtual displacements. Navier-type closed form solution of GLPT, is derived for simply supported plate, made of orthotropic laminae, loaded by harmonic and uniform distribution of transverse pressure. Results are compared with 3D elasticity solutions and excellent agreement is found.

  17. Monotone positive solution for three-point boundary value problem

    Institute of Scientific and Technical Information of China (English)

    SUN Yong-ping

    2008-01-01

    In this paper, the existence of monotone positive solution for the following secondorder three-point boundary value problem is studied:x"(t)+f(t,x(t))=0,0solution are obtained and the bounds of solution are given.At last,an example is given to illustrate the result of the paper.

  18. Analyticity of solutions for quasilinear wave equations and other quasilinear systems

    OpenAIRE

    Kuksin, Sergei; Nadirashvili, Nikolai

    2012-01-01

    We prove the persistence of analyticity for classical solution of the Cauchy problem for quasilinear wave equations with analytic data. Our results show that the analyticity of solutions, stated by the Cauchy-Kowalewski and Ovsiannikov-Nirenberg theorems, lasts till a classical solution exists. Moreover, they show that if the equation and the Cauchy data are analytic only in a part of space-variables, then a classical solution also is analytic in these variables. The approach applies to other...

  19. Analytic solution of pseudocolloid migration in fractured rock

    International Nuclear Information System (INIS)

    A form of colloid migration that can enhance or retard the migration of a dissolved contaminant in ground water is the sorption of the contaminant on the moving colloidal particulate to form pseudocolloids. In this paper we develop analytical solutions for the interactive migration of radioactive species dissolved in ground water and sorbed as pseudocolloids. The solute and pseudocolloids are assumed to undergo advection and dispersion in a one-dimensional flow field in planar fractures in porous rock. Interaction between pseudocolloid and dissolved species is described by equilibrium sorption. Sorbed species on the pseudocolloids undergo radioactive decay, and pseudocolloids can sorb on fracture surfaces and sediments. Filtration is neglected. The solute can decay and sorb on pseudocolloids, on the fracture surfaces, and on sediments and can diffuse into the porous rock matrix. 1 fig

  20. Analytical solutions for multidimensional transport of a four-member radionuclide decay chain in ground water

    International Nuclear Information System (INIS)

    Analytical solutions based on the Laplace and Fourier transformation techniques are presented for the two- and three-dimensional space-time-dependent convective-dispersive transport of a four-member radionuclide decay chain in homogeneous porous media. The longitudinal dispersion-free solution is also reported. The computation was executed using the MASCOT model on a VAX/VMS-Version 4.1. The solutions are designed for an unbounded medium flow field assumed to be semi-infinite in the direction normal to the source, and infinite orthogonal to the source, with a variety of boundary conditions (single or multiple finite line source or a Gaussian distributed source in the two-dimensional case; single or multiple patch source or bivariate normally distributed source in the three-dimensional case). Radionuclide release modes of the constant and nuclide-dependent type are taken into account. An optimization of the convergence of the integration required by these solutions is achieved after operating a transformation of the infinite interval into the sum of two finite ones. The efficiency of two quadrature formulas (Gauss-Legendre and a fourth-order Newton-Cotes based on an iterative approach) was investigated. Solution accuracy was verified against available one- and two-dimensional analytical solutions. 15 refs

  1. JOVIAN STRATOSPHERE AS A CHEMICAL TRANSPORT SYSTEM: BENCHMARK ANALYTICAL SOLUTIONS

    International Nuclear Information System (INIS)

    We systematically investigated the solvable analytical benchmark cases in both one- and two-dimensional (1D and 2D) chemical-advective-diffusive systems. We use the stratosphere of Jupiter as an example but the results can be applied to other planetary atmospheres and exoplanetary atmospheres. In the 1D system, we show that CH4 and C2H6 are mainly in diffusive equilibrium, and the C2H2 profile can be approximated by modified Bessel functions. In the 2D system in the meridional plane, analytical solutions for two typical circulation patterns are derived. Simple tracer transport modeling demonstrates that the distribution of a short-lived species (such as C2H2) is dominated by the local chemical sources and sinks, while that of a long-lived species (such as C2H6) is significantly influenced by the circulation pattern. We find that an equator-to-pole circulation could qualitatively explain the Cassini observations, but a pure diffusive transport process could not. For slowly rotating planets like the close-in extrasolar planets, the interaction between the advection by the zonal wind and chemistry might cause a phase lag between the final tracer distribution and the original source distribution. The numerical simulation results from the 2D Caltech/JPL chemistry-transport model agree well with the analytical solutions for various cases.

  2. JOVIAN STRATOSPHERE AS A CHEMICAL TRANSPORT SYSTEM: BENCHMARK ANALYTICAL SOLUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xi; Shia Runlie; Yung, Yuk L., E-mail: xiz@gps.caltech.edu [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)

    2013-04-20

    We systematically investigated the solvable analytical benchmark cases in both one- and two-dimensional (1D and 2D) chemical-advective-diffusive systems. We use the stratosphere of Jupiter as an example but the results can be applied to other planetary atmospheres and exoplanetary atmospheres. In the 1D system, we show that CH{sub 4} and C{sub 2}H{sub 6} are mainly in diffusive equilibrium, and the C{sub 2}H{sub 2} profile can be approximated by modified Bessel functions. In the 2D system in the meridional plane, analytical solutions for two typical circulation patterns are derived. Simple tracer transport modeling demonstrates that the distribution of a short-lived species (such as C{sub 2}H{sub 2}) is dominated by the local chemical sources and sinks, while that of a long-lived species (such as C{sub 2}H{sub 6}) is significantly influenced by the circulation pattern. We find that an equator-to-pole circulation could qualitatively explain the Cassini observations, but a pure diffusive transport process could not. For slowly rotating planets like the close-in extrasolar planets, the interaction between the advection by the zonal wind and chemistry might cause a phase lag between the final tracer distribution and the original source distribution. The numerical simulation results from the 2D Caltech/JPL chemistry-transport model agree well with the analytical solutions for various cases.

  3. Electromagnetic wave theory for boundary-value problems an advanced course on analytical methods

    CERN Document Server

    Eom, Hyo J

    2004-01-01

    Electromagnetic wave theory is based on Maxwell's equations, and electromagnetic boundary-value problems must be solved to understand electromagnetic scattering, propagation, and radiation. Electromagnetic theory finds practical applications in wireless telecommunications and microwave engineering. This book is written as a text for a two-semester graduate course on electromagnetic wave theory. As such, Electromagnetic Wave Theory for Boundary-Value Problems is intended to help students enhance analytic skills by solving pertinent boundary-value problems. In particular, the techniques of Fourier transform, mode matching, and residue calculus are utilized to solve some canonical scattering and radiation problems.

  4. Approximate analytical solutions to the condensation-coagulation equation of aerosols

    DEFF Research Database (Denmark)

    Smith, Naftali R.; Shaviv, Nir J.; Svensmark, Henrik

    2016-01-01

    We present analytical solutions to the steady state nucleation-condensation-coagulation equation of aerosols in the atmosphere. These solutions are appropriate under different limits but more general than previously derived analytical solutions. For example, we provide an analytic solution to the...

  5. Analytical solution to a fracture problem in a tough layered structure

    Science.gov (United States)

    Hamamoto, Yukari; Okumura, Ko

    2008-08-01

    Nacre causes the shining beauty of pearl due to its remarkable layered structure, which is also strong. We reconsider a simplified layered model of nacre proposed previously [Okumura and de Gennes, Eur. Phys. J. E 4, 121 (2001)] and obtain an analytical solution to a fundamental crack problem. The result asserts that the fracture toughness is enhanced due to a large displacement around the crack tip (even if the crack-tip stress is not reduced). The derivation offers ideas for solving a number of boundary problems for partial differential equations important in many fields.

  6. An analytical solution for the magneto-electro-elastic bimorph beam forced vibrations problem

    International Nuclear Information System (INIS)

    Based on the Timoshenko beam theory and on the assumption that the electric and magnetic fields can be treated as steady, since elastic waves propagate very slowly with respect to electromagnetic ones, a general analytical solution for the transient analysis of a magneto-electro-elastic bimorph beam is obtained. General magneto-electric boundary conditions can be applied on the top and bottom surfaces of the beam, allowing us to study the response of the bilayer structure to electromagnetic stimuli. The model reveals that the magneto-electric loads enter the solution as an equivalent external bending moment per unit length and as time-dependent mechanical boundary conditions through the definition of the bending moment. Moreover, the influences of the electro-mechanic, magneto-mechanic and electromagnetic coupling on the stiffness of the bimorph stem from the computation of the beam equivalent stiffness constants. Free and forced vibration analyses of both multiphase and laminated magneto-electro-elastic composite beams are carried out to check the effectiveness and reliability of the proposed analytic solution

  7. An analytical solution for the magneto-electro-elastic bimorph beam forced vibrations problem

    Science.gov (United States)

    Milazzo, A.; Orlando, C.; Alaimo, A.

    2009-08-01

    Based on the Timoshenko beam theory and on the assumption that the electric and magnetic fields can be treated as steady, since elastic waves propagate very slowly with respect to electromagnetic ones, a general analytical solution for the transient analysis of a magneto-electro-elastic bimorph beam is obtained. General magneto-electric boundary conditions can be applied on the top and bottom surfaces of the beam, allowing us to study the response of the bilayer structure to electromagnetic stimuli. The model reveals that the magneto-electric loads enter the solution as an equivalent external bending moment per unit length and as time-dependent mechanical boundary conditions through the definition of the bending moment. Moreover, the influences of the electro-mechanic, magneto-mechanic and electromagnetic coupling on the stiffness of the bimorph stem from the computation of the beam equivalent stiffness constants. Free and forced vibration analyses of both multiphase and laminated magneto-electro-elastic composite beams are carried out to check the effectiveness and reliability of the proposed analytic solution.

  8. Analytical solutions of transport problems in anisotropic media

    International Nuclear Information System (INIS)

    Recently, the problem of neutron transport in anisotropic media has received new attention in connection with safety studies of water reactors and design of gas-cooled systems. In situations presenting large voided regions, as the axial streaming is dominating with respect to the transverse one, the average properties of the homogenized material should physically account for such macroscopic anisotropy. Hence, it is suggested that cell calculations produce anisotropic average cross sections, e.g., axial (σA) and transverse (σT) values. Since material anisotropy is due to leakage, as a first-step approximation, the medium can be considered isotropic with respect to scattering phenomena. Transport codes are currently being adapted to include anisotropic cross sections. An important aspect of code development is the validation of algorithms by analytical benchmarks. For that purpose, the present work is devoted to the fully analytical solution of transport problems in slab geometry

  9. Analytical solutions for finite cylindrical dynamic cavity expansion in compressible elastic-plastic materials

    Institute of Scientific and Technical Information of China (English)

    甄明; 蒋志刚; 宋殿义; 刘飞

    2014-01-01

    Analytical solutions for the dynamic cylindrical cavity expansion in a com-pressible elastic-plastic cylinder with a finite radius are developed by taking into account of the effect of lateral free boundary, which are different from the traditional cavity expan-sion models for targets with infinite dimensions. The finite cylindrical cavity expansion process begins with an elastic-plastic stage followed by a plastic stage. The elastic-plastic stage ends and the plastic stage starts when the plastic wave front reaches the lateral free boundary. Approximate solutions of radial stress on cavity wall are derived by using the Von-Mise yield criterion and Forrestal’s similarity transformation method. The effects of the lateral free boundary and finite radius on the radial stress on the cavity wall are discussed, and comparisons are also conducted with the finite cylindrical cavity expansion in incompressible elastic-plastic materials. Numerical results show that the lateral free boundary has significant influence on the cavity expansion process and the radial stress on the cavity wall of metal cylinder with a finite radius.

  10. Cooling and warming laws: an exact analytical solution

    International Nuclear Information System (INIS)

    This paper deals with temperature variations over time of objects placed in a constant-temperature environment in the presence of thermal radiation. After a historical introduction, the paper discusses cooling and warming laws, by taking into account first solely object-environment energy exchange by thermal radiation, and then adding object-environment heat exchange by convection. These processes are usually evaluated by approximating the law of exchange of thermal radiation by a linear relationship between power exchange and temperature difference. In contrast, in this paper an exact analytical solution considering Stefan's fourth power law is provided, under some general hypotheses, for both cases. A comparison with exponential approximations and with a historical law proposed by Dulong and Petit in 1817 is presented. Data of an experiment are used to test the analytical solution: the test has allowed evaluating the heat transfer coefficient h of the experiment and has shown that our solution provides a better fit with the measured values than any exponential function. The topic is developed in a way which can be suitable both for undergraduate students and for general physicists.

  11. Analytic theory of curvature effects for wave problems with general boundary conditions

    DEFF Research Database (Denmark)

    Willatzen, Morten; Gravesen, Jens; Voon, L. C. Lew Yan

    2010-01-01

    A formalism based on a combination of differential geometry and perturbation theory is used to obtain analytic expressions for confined eigenmode changes due to general curvature effects. In cases of circular-shaped and helix-shaped structures, where alternative analytic solutions can be found, the...

  12. Numerical and analytical solutions for problems relevant for quantum computers

    International Nuclear Information System (INIS)

    Quantum computers are one of the next technological steps in modern computer science. Some of the relevant questions that arise when it comes to the implementation of quantum operations (as building blocks in a quantum algorithm) or the simulation of quantum systems are studied. Numerical results are gathered for variety of systems, e.g. NMR systems, Josephson junctions and others. To study quantum operations (e.g. the quantum fourier transform, swap operations or multiply-controlled NOT operations) on systems containing many qubits, a parallel C++ code was developed and optimised. In addition to performing high quality operations, a closer look was given to the minimal times required to implement certain quantum operations. These times represent an interesting quantity for the experimenter as well as for the mathematician. The former tries to fight dissipative effects with fast implementations, while the latter draws conclusions in the form of analytical solutions. Dissipative effects can even be included in the optimisation. The resulting solutions are relaxation and time optimised. For systems containing 3 linearly coupled spin (1)/(2) qubits, analytical solutions are known for several problems, e.g. indirect Ising couplings and trilinear operations. A further study was made to investigate whether there exists a sufficient set of criteria to identify systems with dynamics which are invertible under local operations. Finally, a full quantum algorithm to distinguish between two knots was implemented on a spin(1)/(2) system. All operations for this experiment were calculated analytically. The experimental results coincide with the theoretical expectations. (orig.)

  13. Analytical Solution of the Bosonic Three-Body Problem

    International Nuclear Information System (INIS)

    We revisit the problem of three identical bosons in free space, which exhibits a universal hierarchy of bound states (Efimov trimers). Modeling a narrow Feshbach resonance within a two-channel description, we map the integral equation for the three-body scattering amplitude to a one-dimensional Schroedinger-type single-particle equation, where an analytical solution of exponential accuracy is obtained. We give exact results for the trimer binding energies, the three-body parameter, the threshold to the three-atom continuum, and the recombination rate

  14. Mathematical Model of Suspension Filtration and Its Analytical Solution

    Directory of Open Access Journals (Sweden)

    Normahmad Ravshanov

    2013-01-01

    Full Text Available The work develops advanced mathematical model and computing algorithm to analyze, predict and identify the basic parameters of filter units and their variation ranges. Numerical analytic solution of liquid ionized mixtures filtration was got on their basis. Computing experiments results are presented in graphics form. Calculation results analysis enables to determine the optimum performance of filter units, used for liquid ionized mixtures filtration, food preparation, drug production and water purification. Selection of the most suitable parameters contributes to the improvement of economic and technological efficiency of production and filter units working efficiency.

  15. Analytical Solution of The Two-Qubit Quantum Rabi Model

    CERN Document Server

    Abo-Kahla, Doaa A M; Abdel-Aty, Mahmoud

    2015-01-01

    In this paper, an analytical solution of the two-qubit Rabi model for the general case is presented. Furthermore, a comparison between the information entropies and the Von Neumann entropy $(\\rho_{A})$ is given for some special values of the qubit-photon coupling constants in case of the detuning parameters. It is demonstrated that oscillations of the occupation probabilities $\\rho_{11}, \\rho_{22}, \\rho_{33}$ and $\\rho_{44}$ are equivalent to the case of the spontaneous emission. The occupation probability $\\rho_{11}$ reaches the case of sudden death, when the detuning parameters $\\Delta_{2}$ equals zero.

  16. Regression techniques and analytical solutions to demonstrate intrinsic bioremediation

    International Nuclear Information System (INIS)

    It is now generally recognized that a major factor responsible for the attenuation and mass reduction of benzene, toluene, ethylbenzene, and xylenes (BTEX) in groundwater plumes is hydrocarbon biodegradation by indigenous microorganisms in aquifer material. Their objective is to apply well-known regression techniques and analytical solutions to estimate the contribution of advection, dispersion, sorption, and biodecay to the overall attenuation of petroleum hydrocarbons. These calculations yield an apparent biodecay rate based on field data. This biodecay rate is a significant portion of the overall attenuation in stable, dissolved hydrocarbon plumes

  17. Approximate analytical solutions of the baby Skyrme model

    CERN Document Server

    Ioannidou, T A; Zakrzewski, W J

    2002-01-01

    In present paper we show that many properties of the baby skyrmions, which have been determined numerically, can be understood in terms of an analytic approximation. In particular, we show that this approximation captures properties of the multiskyrmion solutions (derived numerically) such as their stability towards decay into various channels, and that it is more accurate for the "new baby Skyrme model" which describes anisotropic physical systems in terms of multiskyrmion fields with axial symmetry. Some universal characteristics of configurations of this kind are demonstrated, which do not depend on their topological number.

  18. An analytical model for solute transport in an infiltration tracer test in soil with a shallow groundwater table

    Science.gov (United States)

    Liang, Ching-Ping; Hsu, Shao-Yiu; Chen, Jui-Sheng

    2016-09-01

    It is recommended that an in-situ infiltration tracer test is considered for simultaneously determining the longitudinal and transverse dispersion coefficients in soil. Analytical solutions have been derived for two-dimensional advective-dispersive transport in a radial geometry in the literature which can be used for interpreting the result of such a tracer test. However, these solutions were developed for a transport domain with an unbounded-radial extent and an infinite thickness of vadose zone which might not be realistically manifested in the actual solute transport during a field infiltration tracer test. Especially, the assumption of infinite thickness of vadose zone should be invalid for infiltration tracer tests conducted in soil with a shallow groundwater table. This paper describes an analytical model for interpreting the results of an infiltration tracer test based on improving the transport domain with a bounded-radial extent and a finite thickness of vadose zone. The analytical model is obtained with the successive application of appropriate integral transforms and their corresponding inverse transforms. A comparison of the newly derived analytical solution against the previous analytical solutions in which two distinct sets of radial extent and thickness of vadose zone are considered is conducted to determine the influence of the radial and exit boundary conditions on the solute transport. The results shows that both the radial and exit boundary conditions substantially affect the trailing segment of the breakthrough curves for a soil medium with large dispersion coefficients. Previous solutions derived for a transport domain with an unbounded-radial and an infinite thickness of vadose zone boundary conditions give lower concentration predictions compared with the proposed solution at late times. Moreover, the differences between two solutions are amplified when the observation positions are near the groundwater table. In addition, we compare our

  19. RESEARCH OF INTERACTIONS BETWEEN SHEAR FRACTURES ON THE BASIS OF APPROXIMATE ANALYTICAL ELASTIC SOLUTIONS

    Directory of Open Access Journals (Sweden)

    Anastasia S. Lermontova

    2015-09-01

    Full Text Available The article describes a method yielding approximate analytical solutions under the theory of elasticity for a set of interacting arbitrarily spaced shear fractures. Accurate analytical solutions of this problem are now available only for the simplest individual cases, such as a single fracture or two collinear fractures. A large amount of computation is required to yield a numerical solution for a case considering arbitrary numbers and locations of fractures, while this problem has important practical applications, such as assessment of the state of stress in seismically active regions, forecasts of secondary destruction impacts near systems of large faults, studies of reservoir properties of the territories comprising oil and gas provinces.In this study, an approximate estimation is obtained with the following simplification assumptions: (1 functions showing shear of fractures’ borders are determined similar to the shear function for a single fracture, and (2 boundary conditions for the fractures are specified in the integrated form as mean values along each fracture. Upon simplification, the solution is obtained through the system of linear algebraic equations for unknown values of tangential stress drop. With this approach, the accuracy of approximate solutions is consistent with the accuracy of the available data on real fractures.The reviewed examples of estimations show that the resultant stress field is dependent on the number, size and location of fractures and the sequence of displacements of the fractures’ borders.

  20. Analytical dynamic solution of a flexible cable-suspended manipulator

    Science.gov (United States)

    Bamdad, Mahdi

    2013-12-01

    Cable-suspended manipulators are used in large scale applications with, heavy in weight and long in span cables. It seems impractical to maintain cable assumptions of smaller robots for large scale manipulators. The interactions among the cables, platforms and actuators can fully evaluate the coupled dynamic analysis. The structural flexibility of the cables becomes more pronounced in large manipulators. In this paper, an analytic solution is provided to solve cable vibration. Also, a closed form solution can be adopted to improve the dynamic response to flexibility. The output is provided by the optimal torque generation subject to the actuator limitations in a mechatronic sense. Finally, the performance of the proposed algorithm is examined through simulations.

  1. A general solution for vertical-drain consolidation with impeded drainage boundaries

    Institute of Scientific and Technical Information of China (English)

    付崔伟; 雷国辉

    2016-01-01

    An analytical solution is derived from the generalized governing equations of equal-strain consolidation with vertical drains under multi-ramp surcharge preloading. The hydraulic boundary conditions at both top and bottom of the consolidating soil are modelled as impeded drainage. The impeded drainage is described by using the third type boundary condition with a characteristic factor of drainage efficiency. Fully drained and undrained boundary conditions can also be modelled by applying an infinite and a zero characteristic factor, respectively. Simultaneous radial and vertical flow conditions are considered, together with the effects of drain resistance and smear. An increase in total stress due to multi-ramp loading is reasonably modelled as a function of both time and depth. A solution to calculate excess pore-water pressure at any arbitrary point in soil is derived, and the overall average degree of consolidation is obtained. It shows that the proposed solution can be used to analyze not only vertical-drain consolidation but also one-dimensional consolidation under either one-way or two-way vertical drainage conditions. The characteristic factors of drainage efficiency of top and bottom boundaries have a potentially important influence on consolidation. The boundary may be considered fully drained when the characteristic factor is greater than 100 and fully undrained when the characteristic factor is less than 0.1. The stress distribution along depth induced by the surcharge loading has a limited effect on the overall average degree of consolidation. However, it has a significant effect on the dissipation of excess pore-water pressure.

  2. A Three-Dimensional Analytical Solution for the Study of Air Pollutant Dispersion in a Finite Layer

    Science.gov (United States)

    Marie, Ema'a. Ema'a. Jean; Hubert, Ben-Bolie Germain; Patrice, Ele Abiama; Zarma, Ali; Pierre, Owono Ateba

    2015-05-01

    We present a closed-form analytical solution for the advection-diffusion equation, where the planetary boundary layer is divided into subdomains, where in each subdomain averaged values of eddy diffusivity and wind speed are assumed. The solution procedure combines an appropriate auxiliary eigenvalue problem with mathematical induction. A transcendental equation giving the eigenvalues for any numbers of subdomains is also developed. Convergence of the solution is numerically verified. The solution is used to evaluate the model against the Copenhagen experiment and computed results are in agreement with experimental ones.

  3. A closed-form exact solution for the value of American put and its optimal exercise boundary (Invited Paper)

    Science.gov (United States)

    Zhu, Song-Ping

    2005-05-01

    Searching for a closed-form exact solution for American put options under the Black-Scholes framework has been a long standing problem in the past; many researchers believe that it is impossible to find such a solution. In this paper, a closed-form exact solution, in the form of a Taylor's series expansion, of the well-known Black-Scholes equation is presented for the first time. As a result of this analytic solution, the optimal exercise boundary, which is the main difficulty of the problem, is found as an explicit function of the risk-free interest rate, the volatility and the time to expiration.

  4. Theoretical progress in non-equilibrium grain-boundary segregation(II):Micro-mechanism of grain boundary anelastic relaxation and its analytical formula

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Finding the internal-friction peak of grain boundary anelastic relaxation was one of the important breakthroughs in the study of internal friction in the last century.But the micro-mechanism of grain boundary anelastic relaxations is still obscure.Based on the observations of the grain boundary seg-regation or depletion of solute induced by an applied stress,the following micro-mechanism was suggested:grain-boundaries will work as sources to emit vacancies when a compressive stress is exerted on them and as sinks to absorb vacancies when a tensile stress is exerted,inducing grain-boundary depletion or segregation of solute,respectively.The equations of vacancy and solute con-centrations at grain boundaries were established under the equilibrium of grain-boundary anelastic relaxation.With these the kinetic equations were established for grain boundary segregation and depletion during the grain boundary relaxation progress.

  5. New chemical evolution analytical solutions including environment effects

    CERN Document Server

    Spitoni, E

    2015-01-01

    In the last years, more and more interest has been devoted to analytical solutions, including inflow and outflow, to study the metallicity enrichment in galaxies. In this framework, we assume a star formation rate which follows a linear Schmidt law, and we present new analytical solutions for the evolution of the metallicity (Z) in galaxies. In particular, we take into account environmental effects including primordial and enriched gas infall, outflow, different star formation efficiencies, and galactic fountains. The enriched infall is included to take into account galaxy-galaxy interactions. Our main results can be summarized as: i) when a linear Schmidt law of star formation is assumed, the resulting time evolution of the metallicity Z is the same either for a closed-box model or for an outflow model. ii) The mass-metallicity relation for galaxies which suffer a chemically enriched infall, originating from another evolved galaxy with no pre-enriched gas, is shifted down in parallel at lower Z values, if co...

  6. Analytic solutions of tunneling time through smooth barriers

    Science.gov (United States)

    Xiao, Zhi; Huang, Hai

    2016-03-01

    In the discussion of temporary behaviors of quantum tunneling, people usually like to focus their attention on rectangular barrier with steep edges, or to deal with smooth barrier with semi-classical or even numerical calculations. Very few discussions on analytic solutions of tunneling through smooth barrier appear in the literature. In this paper, we provide two such examples, a semi-infinite long barrier V ( x ) = /A 2 [ 1 + tanh ( x / a ) ] and a finite barrier V(x) = A sech2(x/a). To each barrier, we calculate the associated phase time and dwell time after obtaining the analytic solution. The results show that, different from rectangular barrier, phase time or dwell time does increase with the length parameter a controlling the effective extension of the barrier. More interestingly, for the finite barrier, phase time or dwell time exhibits a peak in k-space. A detailed analysis shows that this interesting behavior can be attributed to the strange tunneling probability Ts(k), i.e., Ts(k) displays a unit step function-like profile Θ(k - k0), especially when a is large, say, a ≫ 1/κ, 1/k. And k 0 ≡ √{ m A } / ħ is exactly where the peak appears in phase or dwell time k-spectrum. Thus only those particles with k in a very narrow interval around k0 are capable to dwell in the central region of the barrier sufficiently long.

  7. Decision exploration lab: a visual analytics solution for decision management.

    Science.gov (United States)

    Broeksema, Bertjan; Baudel, Thomas; Telea, Arthur G; Crisafulli, Paolo

    2013-12-01

    We present a visual analytics solution designed to address prevalent issues in the area of Operational Decision Management (ODM). In ODM, which has its roots in Artificial Intelligence (Expert Systems) and Management Science, it is increasingly important to align business decisions with business goals. In our work, we consider decision models (executable models of the business domain) as ontologies that describe the business domain, and production rules that describe the business logic of decisions to be made over this ontology. Executing a decision model produces an accumulation of decisions made over time for individual cases. We are interested, first, to get insight in the decision logic and the accumulated facts by themselves. Secondly and more importantly, we want to see how the accumulated facts reveal potential divergences between the reality as captured by the decision model, and the reality as captured by the executed decisions. We illustrate the motivation, added value for visual analytics, and our proposed solution and tooling through a business case from the car insurance industry. PMID:24051763

  8. Creation of the CMB blackbody spectrum: precise analytic solutions

    CERN Document Server

    Khatri, Rishi

    2012-01-01

    The blackbody spectrum of CMB was created behind the blackbody surface at redshifts $z\\gtrsim 2\\times 10^6$. At earlier times, the Universe was dense and hot enough that complete thermal equilibrium between baryonic matter (electrons and ions) and photons could be established. Any perturbation away from the blackbody spectrum was suppressed exponentially. New physics, for example annihilation and decay of dark matter, can add energy and photons to CMB at redshifts $z\\gtrsim 10^5$ and result in a non-zero chemical potential ($\\mu$) of CMB. Precise evolution of the CMB spectrum around the critical redshift of $z\\gtrsim 2\\times 10^6$ is required in order to calculate the $\\mu$-type spectral distortion. Although numerical calculation of important processes involved (double Compton process, comptonization and bremsstrahlung) is not difficult, analytic solutions are much faster and easier to calculate and provide valuable physical insights. We provide precise (better than 1%) analytic solutions for the decay of $\\m...

  9. Grain-boundary migration in nonstoichiometric solid solutions of magnesium aluminate spinel 2; Effects of grain-boundary nonstoichiometry

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Y.M. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Dept. of Materials Science and Engineering); Kingery, W.D. (Arizona Univ., Tucson, AZ (USA))

    1990-05-01

    The grain-boundary chemistry of magnesium aluminate spinel solid solutions MgO {center dot} nAl{sub 2}O{sub 3} has been investigated in order to understand the mechanism of grain-boundary migration. It is found that although segregation of impurity Ca and Si is common, much larger deviations in grain-boundary stoichiometry are present. There is an excess of Al and O relative to Mg at grain boundaries in all compositions. Grain-boundary migration appears to be rate-limited by solute drag from intrinsic defects accommodating lattice nonstoichiometry, rather than by extrinsic solutes, consistent with the observed impurity tolerance of grain-boundary mobility. Different rate-limiting defects are proposed for magnesia-rich and alumina-rich spinels.

  10. Analytical Solution of Projectile Motion with Quadratic Resistance and Generalisations

    CERN Document Server

    Ray, Shouryya

    2013-01-01

    The paper considers the motion of a body under the influence of gravity and drag of the surrounding fluid. Depending on the fluid mechanical regime, the drag force can exhibit a linear, quadratic or even more general dependence on the velocity of the body relative to the fluid. The case of quadratic drag is substantially more complex than the linear case, as it nonlinearly couples both components of the momentum equation, and no explicit analytic solution is known for a general trajectory. After a detailed account of the literature, the paper provides such a solution in form of a series expansion. This result is discussed in detail and related to other approaches previously proposed. In particular, it is shown to yield certain approximate solutions proposed in the literature as limiting cases. The solution technique employs a strategy to reduce systems of ordinary differential equations with a triangular dependence of the right-hand side on the vector of unknowns to a single equation in an auxiliary variable....

  11. Bondi-Hoyle-Lyttleton accretion flow revisited: Analytic solution

    Science.gov (United States)

    Matsuda, Takuya; Isaka, Hiromu; Ohsugi, Yukimasa

    2015-11-01

    The time-steady equation for a 1D wind accretion flow, i.e. the Bondi-Hoyle-Lyttleton (BHL) equation, is investigated analytically. The BHL equation is well known to have infinitely many solutions. Traditionally, the accretion radius has been assumed to be 2textit {GM}/v_{infty }2, but its mathematical foundation has not been clarified because of the non-uniqueness of the solution. Here, we assume that the solution curves possess physically nice characteristics, i.e. velocity and line mass-density increase monotonically with radial distance. This condition restricts the accretion radius to the range left (0.71 - 1.0right ) × 2textit {GM}/v_{infty }2. Further assumptions, specifically, that the solution curves for velocity and line mass-density are convex upward, restrict the accretion radius to (0.84 - 0.94) × 2textit {GM}/v_{infty }2, and 0.90 × 2textit {GM}/v_{infty }2, respectively. Therefore, we conclude that the accretion radius is almost uniquely determined to be 0.90 × 2textit {GM}/v_{infty }2.

  12. Exact analytical solution of shear-induced flexural vibration of functionally graded piezoelectric beam

    Science.gov (United States)

    Sharma, Pankaj; Parashar, Sandeep Kumar

    2016-05-01

    The priority of this paper is to obtain the exact analytical solution for free flexural vibration of FGPM beam actuated using the d15 effect. In piezoelectric actuators, the potential use of d15 effect has been of particular interest for engineering applications since shear piezoelectric coefficient d15 is much higher than the other piezoelectric coupling constants d31 and d33. The applications of shear actuators are to induce and control the flexural vibrations of beams and plates. In this study, a modified Timoshenko beam theory is used where electric potential is assumed to vary sinusoidaly along the thickness direction. The material properties are assumed to be graded across the thickness in accordance with power law distribution. Hamilton`s principle is employed to obtain the equations of motion along with the associated boundary conditions for FGPM beams. Exact analytical solution is derived thus obtained equations of motion. Results for clamped-clamped and clamped-free boundary conditions are presented. The presented result and method shell serve as benchmark for comparing the results obtained from the other approximate methods.

  13. Analytic electrostatic solution of an axisymmetric accelerator gap

    International Nuclear Information System (INIS)

    Numerous computer codes calculate beam dynamics of particles traversing an accelerating gap. In order to carry out these calculations the electric field of a gap must be determined. The electric field is obtained from derivatives of the scalar potential which solves Laplace's equation and satisfies the appropriate boundary conditions. An integral approach for the solution of Laplace's equation is used in this work since the objective is to determine the potential and fields without solving on a traditional spatial grid. The motivation is to quickly obtain forces for particle transport, and eliminate the need to keep track of a large number of grid point fields. The problem then becomes one of how to evaluate the appropriate integral. In this work the integral solution has been converted to a finite sum of easily computed functions. Representing the integral solution in this manner provides a readily calculable formulation and avoids a number of difficulties inherent in dealing with an integral that can be weakly convergent in some regimes, and is, in general, highly oscillatory

  14. Exact analytical solution to three-dimensional phase change heat transfer problems in biological tissues subject to freezing

    Institute of Scientific and Technical Information of China (English)

    Fang-fang LI; Jing LIU; Kai YUE

    2009-01-01

    Analytically solving a three-dimensional (3-D) bioheat transfer problem with phase change during a freezing process is extremely difficult but theoretically important. The moving heat source model and the Green function method are introduced to deal with the cryopreservation process of in vitro biomaterials. Exact solutions for the 3-D temper-ature transients of tissues under various boundary conditions, such as totally convective cooling, totally fixed temperature cooling and a hybrid between them on tissue surfaces, are obtained. Furthermore, the cryosurgical process in living tissues subject to freezing by a single or multiple cryoprobes is also analytically solved. A closed-form analytical solution to the bioheat phase change process is derived by considering contributions from blood perfusion heat transfer, metabolic heat generation, and heat sink of a cryoprobe. The present method is expected to have significant value for analytically solving complex bioheat transfer problems with phase change.

  15. A non-grey analytical model for irradiated atmospheres. II: Analytical vs. numerical solutions

    CERN Document Server

    Parmentier, Vivien; Fortney, Jonathan J; Marley, Mark S

    2013-01-01

    The recent discovery and characterization of the diversity of the atmospheres of exoplanets and brown dwarfs calls for the development of fast and accurate analytical models. In this paper we first quantify the accuracy of the analytical solution derived in paper I for an irradiated, non-grey atmosphere by comparing it to a state-of-the-art radiative transfer model. Then, using a grid of numerical models, we calibrate the different coefficients of our analytical model for irradiated solar-composition atmospheres of giant exoplanets and brown dwarfs. We show that the so-called Eddington approximation used to solve the angular dependency of the radiation field leads to relative errors of up to 5% on the temperature profile. For grey or semi-grey atmospheres we show that the presence of a convective zone has a limited effect on the radiative atmosphere above it and leads to modifications of the radiative temperature profile of order 2%. However, for realistic non-grey planetary atmospheres, the presence of a con...

  16. Exact analytical solutions to the master equation of quantum Brownian motion for a general environment

    CERN Document Server

    Fleming, C H; Hu, B L

    2010-01-01

    We revisit the model of a quantum Brownian oscillator linearly coupled to an environment of quantum oscillators at finite temperature. By introducing a compact and particularly well-suited formulation, we give a rather quick and direct derivation of the master equation and its solutions for general spectral functions and arbitrary temperatures. The flexibility of our approach allows for an immediate generalization to cases with an external force and with an arbitrary number of Brownian oscillators. More importantly, we point out an important mathematical subtlety concerning boundary-value problems for integro-differential equations which led to incorrect master equation coefficients and impacts on the description of nonlocal dissipation effects in all earlier derivations. Furthermore, we provide explicit, exact analytical results for the master equation coefficients and its solutions in a wide variety of cases, including ohmic, sub-ohmic and supra-ohmic environments with a finite cut-off.

  17. An analytic solution of steady Stokes flow on a rotating polar cap

    International Nuclear Information System (INIS)

    An analytic solution of two-dimensional, steady, linear, viscous flow on a polar cap-the polar region of a sphere that lies above (or below) a given plane normal to the rotation axis-rotating about its center is obtained. Inflow and outflow on the boundary of the polar cap drive the fluid motion. The solution of the stream function is expressed as the Fourier series in longitudes and the associated Legendre functions of complex degrees in cosines of colatitudes. Fluid particles move almost along lines of constant latitude, some circulate cyclonically and others anticyclonically, in the geostrophic balance everywhere except near the north pole where the flow is relatively slow and the viscous force dominates over the Coriolis force. Our results support the approximation analysis and laboratory experiment studied by Imawaki and Takano (1974 Deep-Sea Res. 21 69-77).

  18. Unified semi-analytical wall boundary conditions applied to 2-D incompressible SPH

    Science.gov (United States)

    Leroy, A.; Violeau, D.; Ferrand, M.; Kassiotis, C.

    2014-03-01

    This work aims at improving the 2-D incompressible SPH model (ISPH) by adapting it to the unified semi-analytical wall boundary conditions proposed by Ferrand et al. [10]. The ISPH algorithm considered is as proposed by Lind et al. [25], based on the projection method with a divergence-free velocity field and using a stabilising procedure based on particle shifting. However, we consider an extension of this model to Reynolds-Averaged Navier-Stokes equations based on the k-ɛ turbulent closure model, as done in [10]. The discrete SPH operators are modified by the new description of the wall boundary conditions. In particular, a boundary term appears in the Laplacian operator, which makes it possible to accurately impose a von Neumann pressure wall boundary condition that corresponds to impermeability. The shifting and free-surface detection algorithms have also been adapted to the new boundary conditions. Moreover, a new way to compute the wall renormalisation factor in the frame of the unified semi-analytical boundary conditions is proposed in order to decrease the computational time. We present several verifications to the present approach, including a lid-driven cavity, a water column collapsing on a wedge and a periodic schematic fish-pass. Our results are compared to Finite Volumes methods, using Volume of Fluids in the case of free-surface flows. We briefly investigate the convergence of the method and prove its ability to model complex free-surface and turbulent flows. The results are generally improved when compared to a weakly compressible SPH model with the same boundary conditions, especially in terms of pressure prediction.

  19. Local existence of solution to free boundary value problem for compressible Navier-Stokes equations

    OpenAIRE

    Liu, Jian

    2015-01-01

    This paper is concerned with the free boundary value problem for multi-dimensional Navier-Stokes equations with density-dependent viscosity where the flow density vanishes continuously across the free boundary. A local (in time) existence of weak solution is established, in particular, the density is positive and the solution is regular away from the free boundary.

  20. Analytic solution of Hubbell's model of local community dynamics

    CERN Document Server

    McKane, A; Sole, R; Kane, Alan Mc; Alonso, David; Sole, Ricard

    2003-01-01

    Recent theoretical approaches to community structure and dynamics reveal that many large-scale features of community structure (such as species-rank distributions and species-area relations) can be explained by a so-called neutral model. Using this approach, species are taken to be equivalent and trophic relations are not taken into account explicitly. Here we provide a general analytic solution to the local community model of Hubbell's neutral theory of biodiversity by recasting it as an urn model i.e.a Markovian description of states and their transitions. Both stationary and time-dependent distributions are analysed. The stationary distribution -- also called the zero-sum multinomial -- is given in closed form. An approximate form for the time-dependence is obtained by using an expansion of the master equation. The temporal evolution of the approximate distribution is shown to be a good representation for the true temporal evolution for a large range of parameter values.

  1. Segregation and clustering of solutes at grain boundaries in Mg–rare earth solid solutions

    International Nuclear Information System (INIS)

    The present study validates the previously reported investigations about segregation of rare-earth (RE) elements at grain boundaries in Mg–RE alloys and ultimately provides a direct visualization of the distribution of the solute atoms in the structure of a Mg–Gd alloy. It is demonstrated that Gd forms a solid solution within the Mg matrix in addition to substantial segregation at high-angle grain boundaries in the form of 1–2 nm clusters, with a postulated face-centered cubic Gd structure. The results suggest significant implications for the texture development during alloy processing and recrystallization, and thus for the mechanical behavior and properties of Mg–RE alloys

  2. Measurement of Actinides in Molybdenum-99 Solution Analytical Procedure

    Energy Technology Data Exchange (ETDEWEB)

    Soderquist, Chuck Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weaver, Jamie L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-11-01

    This document is a companion report to a previous report, PNNL 24519, Measurement of Actinides in Molybdenum-99 Solution, A Brief Review of the Literature, August 2015. In this companion report, we report a fast, accurate, newly developed analytical method for measurement of trace alpha-emitting actinide elements in commercial high-activity molybdenum-99 solution. Molybdenum-99 is widely used to produce 99mTc for medical imaging. Because it is used as a radiopharmaceutical, its purity must be proven to be extremely high, particularly for the alpha emitting actinides. The sample of 99Mo solution is measured into a vessel (such as a polyethylene centrifuge tube) and acidified with dilute nitric acid. A gadolinium carrier is added (50 µg). Tracers and spikes are added as necessary. Then the solution is made strongly basic with ammonium hydroxide, which causes the gadolinium carrier to precipitate as hydrous Gd(OH)3. The precipitate of Gd(OH)3 carries all of the actinide elements. The suspension of gadolinium hydroxide is then passed through a membrane filter to make a counting mount suitable for direct alpha spectrometry. The high-activity 99Mo and 99mTc pass through the membrane filter and are separated from the alpha emitters. The gadolinium hydroxide, carrying any trace actinide elements that might be present in the sample, forms a thin, uniform cake on the surface of the membrane filter. The filter cake is first washed with dilute ammonium hydroxide to push the last traces of molybdate through, then with water. The filter is then mounted on a stainless steel counting disk. Finally, the alpha emitting actinide elements are measured by alpha spectrometry.

  3. Solution of a Problem Linear Plane Elasticity with Mixed Boundary Conditions by the Method of Boundary Integrals

    Directory of Open Access Journals (Sweden)

    Nahed S. Hussein

    2014-01-01

    Full Text Available A numerical boundary integral scheme is proposed for the solution to the system of …eld equations of plane. The stresses are prescribed on one-half of the circle, while the displacements are given. The considered problem with mixed boundary conditions in the circle is replaced by two problems with homogeneous boundary conditions, one of each type, having a common solution. The equations are reduced to a system of boundary integral equations, which is then discretized in the usual way, and the problem at this stage is reduced to the solution to a rectangular linear system of algebraic equations. The unknowns in this system of equations are the boundary values of four harmonic functions which define the full elastic solution and the unknown boundary values of stresses or displacements on proper parts of the boundary. On the basis of the obtained results, it is inferred that a stress component has a singularity at each of the two separation points, thought to be of logarithmic type. The results are discussed and boundary plots are given. We have also calculated the unknown functions in the bulk directly from the given boundary conditions using the boundary collocation method. The obtained results in the bulk are discussed and three-dimensional plots are given. A tentative form for the singular solution is proposed and the corresponding singular stresses and displacements are plotted in the bulk. The form of the singular tangential stress is seen to be compatible with the boundary values obtained earlier. The efficiency of the used numerical schemes is discussed.

  4. Mathematical model of complex technical asymmetric system based on numerical-analytical boundary elements method

    Directory of Open Access Journals (Sweden)

    Dina V. Lazareva

    2015-06-01

    Full Text Available A new mathematical model of asymmetric support structure frame type is built on the basis of numerical-analytical boundary elements method (BEM. To describe the design scheme used is the graph theory. Building the model taken into account is the effect of frame members restrained torsion, which presence is due to the fact that these elements are thin-walled. The built model represents a real object as a two-axle semi-trailer platform. To implement the BEM algorithm obtained are analytical expressions of the fundamental functions and vector load components. The effected calculations are based on the semi-trailer two different models, using finite elements and boundary elements methods. The analysis showed that the error between the results obtained on the basis of two numerical methods and experimental data is about 4%, that indicates the adequacy of the proposed mathematical model.

  5. Investigation of wall bounded flows using SPH and the unified semi-analytical wall boundary conditions

    CERN Document Server

    Mayrhofer, Arno; Violeau, Damien; Ferrand, Martin

    2013-01-01

    The semi-analytical wall boundary conditions present a mathematically rigorous framework to prescribe the influence of solid walls in SPH for fluid flows. In this paper they are investigated with respect to the skew-adjoint property which implies exact energy conservation. It will be shown that this property holds only in the limit of the continuous SPH approximation, whereas in the discrete SPH formulation it is only approximately true, leading to numerical noise. This noise, interpreted as form of "turbulence", is treated using an additional volume diffusion term in the continuity equation which we show is equivalent to an approximate Riemann solver. Subsequently two extensions to the boundary conditions are presented. The first dealing with a variable driving force when imposing a volume flux in a periodic flow and the second showing a generalization of the wall boundary condition to Robin type and arbitrary-order interpolation. Two modifications for free-surface flows are presented for the volume diffusio...

  6. General analytical solutions for DC/AC circuit network analysis

    CERN Document Server

    Rubido, Nicolás; Baptista, Murilo S

    2014-01-01

    In this work, we present novel general analytical solutions for the currents that are developed in the edges of network-like circuits when some nodes of the network act as sources/sinks of DC or AC current. We assume that Ohm's law is valid at every edge and that charge at every node is conserved (with the exception of the source/sink nodes). The resistive, capacitive, and/or inductive properties of the lines in the circuit define a complex network structure with given impedances for each edge. Our solution for the currents at each edge is derived in terms of the eigenvalues and eigenvectors of the Laplacian matrix of the network defined from the impedances. This derivation also allows us to compute the equivalent impedance between any two nodes of the circuit and relate it to currents in a closed circuit which has a single voltage generator instead of many input/output source/sink nodes. Contrary to solving Kirchhoff's equations, our derivation allows to easily calculate the redistribution of currents that o...

  7. A Priori Estimates for Solutions of Boundary Value Problems for Fractional-Order Equations

    CERN Document Server

    Alikhanov, A A

    2011-01-01

    We consider boundary value problems of the first and third kind for the diffusionwave equation. By using the method of energy inequalities, we find a priori estimates for the solutions of these boundary value problems.

  8. LIMIT BEHAVIOUR OF SOLUTIONS TO EQUIVALUED SURFACE BOUNDARY VALUE PROBLEM FOR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    LI Fengquan

    2002-01-01

    In this paper, we discuss the limit behaviour of solutions to equivalued surface boundary value problem for parabolic equations when the equivalued surface boundary shrinks to a point and the space dimension of the domain is two or more.

  9. Analytical solutions of the planar cyclic voltammetry process for two soluble species with equal diffusivities and fast electron transfer using the method of eigenfunction expansions

    OpenAIRE

    Adib Samin; Erik Lahti; Jinsuo Zhang

    2015-01-01

    Cyclic voltammetry is a powerful tool that is used for characterizing electrochemical processes. Models of cyclic voltammetry take into account the mass transport of species and the kinetics at the electrode surface. Analytical solutions of these models are not well-known due to the complexity of the boundary conditions. In this study we present closed form analytical solutions of the planar voltammetry model for two soluble species with fast electron transfer and equal diffusivities using th...

  10. POLYNOMIAL SOLUTIONS TO PIEZOELECTRIC BEAMS(Ⅱ)--ANALYTICAL SOLUTIONS TO TYPICAL PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    DING Hao-jiang; JIANG Ai-min

    2005-01-01

    For the orthotropic piezoelectric plane problem, a series of piezoelectric beams is solved and the corresponding analytical solutions are obtained with the trialand-error method on the basis of the general solution in the case of three distinct eigenvalues, in which all displacements, electrical potential, stresses and electrical displacements are expressed by three displacement functions in terms of harmonic polynomials. These problems are cantilever beam with cross force and point charge at free end, cantilever beam and simply-supported beam subjected to uniform loads on the upper and lower surfaces, and cantilever beam subjected to linear electrical potential.

  11. Concerning an analytical solution of some families of Kepler’s transcendental equation

    Directory of Open Access Journals (Sweden)

    Slavica M. Perovich

    2016-03-01

    Full Text Available The problem of finding an analytical solution of some families of Kepler transcendental equation is studied in some detail, by the Special Trans Functions Theory – STFT. Thus, the STFT mathematical approach in the form of STFT iterative methods with a novel analytical solutions are presented. Structure of the STFT solutions, numerical results and graphical simulations confirm the validity of the basic principle of the STFT. In addition, the obtained analytical results are compared with the calculated values of other analytical methods for alternative proving its significance. Undoubtedly, the proposed novel analytical approach implies qualitative improvement in comparison with conventional numerical and analytical methods.

  12. An approximate analytical solution of free convection problem for vertical isothermal plate via transverse coordinate Taylor expansion

    CERN Document Server

    Leble, Sergey

    2013-01-01

    The model under consideration is based on approximate analytical solution of two dimensional stationary Navier-Stokes and Fourier-Kirchhoff equations. Approximations are based on the typical for natural convection assumptions: the fluid noncompressibility and Bousinesq approximation. We also assume that ortogonal to the plate component (x) of velocity is neglectible small. The solution of the boundary problem is represented as a Taylor Series in $x$ coordinate for velocity and temperature which introduces functions of vertical coordinate (y), as coefficients of the expansion. The correspondent boundary problem formulation depends on parameters specific for the problem: Grashoff number, the plate height (L) and gravity constant. The main result of the paper is the set of equations for the coefficient functions for example choice of expansion terms number. The nonzero velocity at the starting point of a flow appears in such approach as a development of convecntional boundary layer theory formulation.

  13. Food Adulteration: From Vulnerability Assessment to New Analytical Solutions.

    Science.gov (United States)

    Cavin, Christophe; Cottenet, Geoffrey; Blancpain, Carine; Bessaire, Thomas; Frank, Nancy; Zbinden, Pascal

    2016-01-01

    Crises related to the presence of melamine in milk or horse meat in beef have been a wake-up call to the whole food industry showing that adulteration of food raw materials is a complex issue. By analysing the situation, it became clear that the risk-based approach applied to ensure the safety related to chemical contaminants in food is not adequate for food fraud. Therefore, a specific approach has been developed to evaluate adulteration vulnerabilities within the food chain. Vulnerabilities will require the development of new analytical solutions. Fingerprinting methodologies can be very powerful in determining the status of a raw material without knowing the identity of each constituent. Milk adulterated by addition of adulterants with very different chemical properties could be detected rapidly by Fourier-transformed mid-infrared spectroscopy (FT-mid-IR) fingerprinting technology. In parallel, a fast and simple multi-analytes liquid-chromatography tandem mass-spectrometry (LC/MS-MS) method has been developed to detect either high levels of nitrogen-rich compounds resulting from adulteration or low levels due to accidental contamination either in milk or in other sensitive food matrices. To verify meat species authenticity, DNA-based methods are preferred for both raw ingredients and processed food. DNA macro-array, and more specifically the Meat LCD Array have showed efficient and reliable meat identification, allowing the simultaneous detection of 32 meat species. While the Meat LCD Array is still a targeted approach, DNA sequencing is a significant step towards an untargeted one. PMID:27198809

  14. Analytical Solution and Physics of a Propellant Damping Device

    Science.gov (United States)

    Yang, H. Q.; Peugeot, John

    2011-01-01

    NASA design teams have been investigating options for "detuning" Ares I to prevent oscillations originating in the vehicle solid-rocket main stage from synching up with the natural resonance of the rest of the vehicle. An experimental work started at NASA MSFC center in 2008 using a damping device showed great promise in damping the vibration level of an 8 resonant tank. However, the mechanisms of the vibration damping were not well understood and there were many unknowns such as the physics, scalability, technology readiness level (TRL), and applicability for the Ares I vehicle. The objectives of this study are to understand the physics of intriguing slosh damping observed in the experiments, to further validate a Computational Fluid Dynamics (CFD) software in propellant sloshing against experiments with water, and to study the applicability and efficiency of the slosh damper to a full scale propellant tank and to cryogenic fluids. First a 2D fluid-structure interaction model is built to model the system resonance of liquid sloshing and structure vibration. A damper is then added into the above model to simulate experimentally observed system damping phenomena. Qualitative agreement is found. An analytical solution is then derived from the Newtonian dynamics for the thrust oscillation damper frequency, and a slave mass concept is introduced in deriving the damper and tank interaction dynamics. The paper will elucidate the fundamental physics behind the LOX damper success from the derivation of the above analytical equation of the lumped Newtonian dynamics. Discussion of simulation results using high fidelity multi-phase, multi-physics, fully coupled CFD structure interaction model will show why the LOX damper is unique and superior compared to other proposed mitigation techniques.

  15. An analytical study of the instability of a superelastic shape memory alloy cylinder subject to practical boundary conditions

    International Nuclear Information System (INIS)

    In this paper, we study phase transitions in a slender circular cylinder composed of a compressible hyperelastic material with a non-convex strain energy function. We aim to construct asymptotic solutions based on an axisymmetrical three-dimensional setting and use the results to describe the key features observed in the experiments by others. The problem of the solution bifurcations of the governing nonlinear partial differential equations (PDEs) is solved through a novel approach involving coupled series–asymptotic expansions. We derive the normal form equation of the original complicated system of nonlinear PDEs. By writing the normal form equation into a first-order dynamical system and with a phase-plane analysis, we deduce the global bifurcation properties and solve the boundary-value problem analytically. The asymptotic solutions in terms of integrals are obtained. The engineering stress–strain curve plotted from the asymptotic solutions can capture some key features of the curve measured in the experiments. It appears that the asymptotic solutions obtained shed certain light on the instability phenomena associated with phase transitions in a cylinder. Also, an important feature of this work is that we consider the clamped end conditions, which are more practical but rarely used in the literature for phase transition problems

  16. The BV solution of the parabolic equation with degeneracy on the boundary

    Directory of Open Access Journals (Sweden)

    Zhan Huashui

    2016-12-01

    Full Text Available Consider a parabolic equation which is degenerate on the boundary. By the degeneracy, to assure the well-posedness of the solutions, only a partial boundary condition is generally necessary. When 1 ≤ α < p – 1, the existence of the local BV solution is proved. By choosing some kinds of test functions, the stability of the solutions based on a partial boundary condition is established.

  17. Embedded Analytical Solutions Improve Accuracy in Convolution-Based Particle Tracking Models using Python

    Science.gov (United States)

    Starn, J. J.

    2013-12-01

    Particle tracking often is used to generate particle-age distributions that are used as impulse-response functions in convolution. A typical application is to produce groundwater solute breakthrough curves (BTC) at endpoint receptors such as pumping wells or streams. The commonly used semi-analytical particle-tracking algorithm based on the assumption of linear velocity gradients between opposing cell faces is computationally very fast when used in combination with finite-difference models. However, large gradients near pumping wells in regional-scale groundwater-flow models often are not well represented because of cell-size limitations. This leads to inaccurate velocity fields, especially at weak sinks. Accurate analytical solutions for velocity near a pumping well are available, and various boundary conditions can be imposed using image-well theory. Python can be used to embed these solutions into existing semi-analytical particle-tracking codes, thereby maintaining the integrity and quality-assurance of the existing code. Python (and associated scientific computational packages NumPy, SciPy, and Matplotlib) is an effective tool because of its wide ranging capability. Python text processing allows complex and database-like manipulation of model input and output files, including binary and HDF5 files. High-level functions in the language include ODE solvers to solve first-order particle-location ODEs, Gaussian kernel density estimation to compute smooth particle-age distributions, and convolution. The highly vectorized nature of NumPy arrays and functions minimizes the need for computationally expensive loops. A modular Python code base has been developed to compute BTCs using embedded analytical solutions at pumping wells based on an existing well-documented finite-difference groundwater-flow simulation code (MODFLOW) and a semi-analytical particle-tracking code (MODPATH). The Python code base is tested by comparing BTCs with highly discretized synthetic steady

  18. A study on evaluation and analytical methods for groundwater flow with considering sea/fresh-water boundary. 1

    International Nuclear Information System (INIS)

    Sea/fresh-water boundary caused by density and concentration balance of sea-water and fresh-water is an important item for groundwater flow evaluation in deep underground near the coast. Also, in order to evaluate groundwater quality, it is important to understand the characteristics of sea/fresh-water boundary, for example boundary shape, salt distribution. In order to establish the evaluation and analytical methods for groundwater flow with considering sea/fresh-water boundary, we investigated the following items in this study. (1) Literature survey and data collection. (2) Investigation of analytical methods. (3) Planning of further study. (author). 78 refs

  19. A study on evaluation and analytical methods for groundwater flow with considering sea/fresh-water boundary. 1

    Energy Technology Data Exchange (ETDEWEB)

    Anezaki, S. [Taisei Corp., Tokyo (Japan)

    1998-03-01

    Sea/fresh-water boundary caused by density and concentration balance of sea-water and fresh-water is an important item for groundwater flow evaluation in deep underground near the coast. Also, in order to evaluate groundwater quality, it is important to understand the characteristics of sea/fresh-water boundary, for example boundary shape, salt distribution. In order to establish the evaluation and analytical methods for groundwater flow with considering sea/fresh-water boundary, we investigated the following items in this study. (1) Literature survey and data collection. (2) Investigation of analytical methods. (3) Planning of further study. (author). 78 refs.

  20. Grain boundary structure and solute segregation in titanium-doped sapphire bicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Seth T.

    2002-05-17

    Solute segregation to ceramic grain boundaries governs material processing and microstructure evolution, and can strongly influence material properties critical to engineering performance. Understanding the evolution and implications of grain boundary chemistry is a vital component in the greater effort to engineer ceramics with controlled microstructures. This study examines solute segregation to engineered grain boundaries in titanium-doped sapphire (Al2O3) bicrystals, and explores relationships between grain boundary structure and chemistry at the nanometer scale using spectroscopic and imaging techniques in the transmission electron microscope (TEM). Results demonstrate dramatic changes in solute segregation stemming from small fluctuations in grain boundary plane and structure. Titanium and silicon solute species exhibit strong tendencies to segregate to non-basal and basal grain boundary planes, respectively. Evidence suggests that grain boundary faceting occurs in low-angle twis t boundaries to accommodate nonequilibrium solute segregation related to slow specimen cooling rates, while faceting of tilt grain boundaries often occurs to expose special planes of the coincidence site lattice (CSL). Moreover, quantitative analysis of grain boundary chemistry indicates preferential segregation of charged defects to grain boundary dislocations. These results offer direct proof that static dislocations in ionic materials can assume a net charge, and emphasize the importance of interactions between charged point, line, and planar defects in ionic materials. Efforts to understand grain boundary chemistry in terms of space charge theory, elastic misfit and nonequilibrium segregation are discussed for the Al2O3 system.

  1. New analytic solutions for modeling vertical gravity gradient anomalies

    Science.gov (United States)

    Kim, Seung-Sep; Wessel, Paul

    2016-05-01

    Modern processing of satellite altimetry for use in marine gravimetry involves computing the along-track slopes of observed sea-surface heights, projecting them into east-west and north-south deflection of the vertical grids, and using Laplace's equation to algebraically obtain a grid of the vertical gravity gradient (VGG). The VGG grid is then integrated via overlapping, flat Earth Fourier transforms to yield a free-air anomaly grid. Because of this integration and associated edge effects, the VGG grid retains more short-wavelength information (e.g., fracture zone and seamount signatures) that is of particular importance for plate tectonic investigations. While modeling of gravity anomalies over arbitrary bodies has long been a standard undertaking, similar modeling of VGG anomalies over oceanic features is not commonplace yet. Here we derive analytic solutions for VGG anomalies over simple bodies and arbitrary 2-D and 3-D sources. We demonstrate their usability in determining mass excess and deficiency across the Mendocino fracture zone (a 2-D feature) and find the best bulk density estimate for Jasper seamount (a 3-D feature). The methodologies used herein are implemented in the Generic Mapping Tools, available from gmt.soest.hawaii.edu.

  2. Analytical solutions for peak and residual uplift resistance of pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Nixon, J.F. [Nixon Geotech Ltd., Calgary, AB (Canada); Oswell, J.M. [Naviq Consulting Inc., Calgary, AB (Canada)

    2010-07-01

    Frost heave can occur on cold pipelines that traverse unfrozen, non permafrost terrain. The stresses experienced by the pipeline are partly a function of the strength of the soil on the non heaving side of the frozen-unfrozen interface. This paper proposed three analytical solutions to estimate the soil uplift resistance by considering the pipeline and soil to act similar to a strip footing, a punching shear failure, and by considering the formation of horizontal crack emanating from the spring line of the pipe. Peak uplift resistance and residual uplift resistance were discussed. Results for full scale pipe and for laboratory scale model pipes were presented, with particular reference to cover depth, temperature and crack width; and limits to residual uplift resistance. It was concluded that the peak uplift resistance and the residual uplift resistance are generally independent and controlled by different factors. The peak resistance is related directly to pipe diameter, and less strongly dependent on springline depth. It is also strongly dependent on soil temperature. However, the residual uplift resistance is strongly dependent on burial depth, weakly dependent on pipe displacement rate and also on soil temperature. 15 refs., 19 figs.

  3. Approximate analytic solutions to the NPDD: Short exposure approximations

    Science.gov (United States)

    Close, Ciara E.; Sheridan, John T.

    2014-04-01

    There have been many attempts to accurately describe the photochemical processes that take places in photopolymer materials. As the models have become more accurate, solving them has become more numerically intensive and more 'opaque'. Recent models incorporate the major photochemical reactions taking place as well as the diffusion effects resulting from the photo-polymerisation process, and have accurately described these processes in a number of different materials. It is our aim to develop accessible mathematical expressions which provide physical insights and simple quantitative predictions of practical value to material designers and users. In this paper, starting with the Non-Local Photo-Polymerisation Driven Diffusion (NPDD) model coupled integro-differential equations, we first simplify these equations and validate the accuracy of the resulting approximate model. This new set of governing equations are then used to produce accurate analytic solutions (polynomials) describing the evolution of the monomer and polymer concentrations, and the grating refractive index modulation, in the case of short low intensity sinusoidal exposures. The physical significance of the results and their consequences for holographic data storage (HDS) are then discussed.

  4. New possibilities of accurate particle characterisation by applying direct boundary models to analytical centrifugation

    Science.gov (United States)

    Walter, Johannes; Thajudeen, Thaseem; Süß, Sebastian; Segets, Doris; Peukert, Wolfgang

    2015-04-01

    Analytical centrifugation (AC) is a powerful technique for the characterisation of nanoparticles in colloidal systems. As a direct and absolute technique it requires no calibration or measurements of standards. Moreover, it offers simple experimental design and handling, high sample throughput as well as moderate investment costs. However, the full potential of AC for nanoparticle size analysis requires the development of powerful data analysis techniques. In this study we show how the application of direct boundary models to AC data opens up new possibilities in particle characterisation. An accurate analysis method, successfully applied to sedimentation data obtained by analytical ultracentrifugation (AUC) in the past, was used for the first time in analysing AC data. Unlike traditional data evaluation routines for AC using a designated number of radial positions or scans, direct boundary models consider the complete sedimentation boundary, which results in significantly better statistics. We demonstrate that meniscus fitting, as well as the correction of radius and time invariant noise significantly improves the signal-to-noise ratio and prevents the occurrence of false positives due to optical artefacts. Moreover, hydrodynamic non-ideality can be assessed by the residuals obtained from the analysis. The sedimentation coefficient distributions obtained by AC are in excellent agreement with the results from AUC. Brownian dynamics simulations were used to generate numerical sedimentation data to study the influence of diffusion on the obtained distributions. Our approach is further validated using polystyrene and silica nanoparticles. In particular, we demonstrate the strength of AC for analysing multimodal distributions by means of gold nanoparticles.

  5. An analytical solution of non-Fourier Chen-Holmes bioheat transfer equation

    Institute of Scientific and Technical Information of China (English)

    GOU Chenhua; CAI Ruixian

    2005-01-01

    An algebraically explicit analytical solution with heat wave effect is derived for the non-Fourier bioheat transfer Chen-Holmes model. Besides its important theoretical meaning (for example, to expand the understanding of heat wave phenomena in living tissues), this analytical solution is also valuable as the benchmark solution to check the numerical calculation and to develop various numerical computational approaches.

  6. Analytical solutions of heat transfer for laminar flow in rectangular channels

    Directory of Open Access Journals (Sweden)

    Rybiński Witold

    2014-12-01

    Full Text Available The paper presents two analytical solutions namely for Fanning friction factor and for Nusselt number of fully developed laminar fluid flow in straight mini channels with rectangular cross-section. This type of channels is common in mini- and microchannel heat exchangers. Analytical formulae, both for velocity and temperature profiles, were obtained in the explicit form of two terms. The first term is an asymptotic solution of laminar flow between parallel plates. The second one is a rapidly convergent series. This series becomes zero as the cross-section aspect ratio goes to infinity. This clear mathematical form is also inherited by the formulae for friction factor and Nusselt number. As the boundary conditions for velocity and temperature profiles no-slip and peripherally constant temperature with axially constant heat flux were assumed (H1 type. The velocity profile is assumed to be independent of the temperature profile. The assumption of constant temperature at the channel’s perimeter is related to the asymptotic case of channel’s wall thermal resistance: infinite in the axial direction and zero in the peripheral one. It represents typical conditions in a minichannel heat exchanger made of metal.

  7. Semi-analytical solutions for the effect of well shut down on rock stability

    Energy Technology Data Exchange (ETDEWEB)

    Han, G.; Ioannidis, M.; Dusseault, M.B. [Waterloo Univ., ON (Canada)

    2002-06-01

    This paper presents three newly developed models to describe the effect of well shut down (or sharp change of production rate) on rock stress distributions. The methods are particularly useful in poorly consolidated rock around a wellbore which may become unstable after the process of well shut down and restart. Analytical solutions for quasi-static pressure recovery processes in a bounded oil reservoir are combined with a poro-elastic geomechanics model in which pressure fluctuations inside the wellbore provide a boundary condition to the formation outside the wellbore. Analytical solutions explain the direct relationships between fluid properties, rock properties and production parameters. Stress fluctuations are examined in the context of rock stability changes resulting from dynamic loading. Model calculations show that the fluctuations of effective stresses and shear stress could reach several hundred kPa due to pressure waves created by the water hammer effect inside a wellbore. The models can be used to quantify the effects of pressure oscillation, resulting from operation at the surface, on the stability of underground rock. It is noted that more research is needed to obtain accurate information on the dynamic response of unconsolidated sandstones to rapidly oscillating pressures before this method can be widely used. The model can be used to evaluate risks such as rock instability. It can also be used to choose which wells may start sanding if they are shut down or started up abruptly. 13 refs., 1 tab., 7 figs., 1 append.

  8. Boundary Integral Solutions to Three-Dimensional Unconfined Darcy's Flow

    Science.gov (United States)

    Lennon, Gerard P.; Liu, Philip L.-F.; Liggett, James A.

    1980-08-01

    The boundary integral equation method (BIEM) is used to solve three-dimensional potential flow problems in porous media. The problems considered here are time dependent and have a nonlinear boundary condition on the free surface. The entire boundary, including the moving free surface, discretized into linear finite elements for the purpose of evaluating the boundary integrals. The technique allows transient, three-dimensional problems to be solved with reasonable computational costs. Numerical examples include recharge through rectangular and circular areas and seepage flow from a surface pond. The examples are used to illustrate the method and show the nonlinear effects.

  9. Local solution for a class of mixed boundary value problems

    International Nuclear Information System (INIS)

    A local method is developed for solving locally partial differential equations with mixed boundary conditions. The method is based on a heuristic idea, properties of diffusion processes, stopping times and the Ito formula for semimartingales. According to the heuristic idea, the diffusion process used for solving locally a partial differential with mixed boundary conditions is stopped when it reaches a Neumann boundary and then restarted inside the domain of definition of this equation at a point depending on the Neumann conditions. The proposed method is illustrated and its accuracy assessed by two simple numerical examples solving locally mixed boundary value problems in one and two space dimensions

  10. An analytical solution for one-dimensional contaminant diffusion through multi-layered system and its applications

    Science.gov (United States)

    Chen, Yunmin; Xie, Haijian; Ke, Han; Chen, Renpeng

    2009-09-01

    An analytical solution for one-dimensional contaminant diffusion through multi-layered media is derived regarding the change of the concentration of contaminants at the top boundary with time. The model accounts for the arbitrary initial conditions and the conditions of zero concentration and zero mass flux on the bottom boundary. The average degree of diffusion of the layered system is introduced on the basis of the solution. The results obtained by the presented analytical solutions agree well with those obtained by the numerical methods presented in the literature papers. The application of the analytical solution to the problem of landfill liner design is illustrated by considering a composite liner consisting of geomembrane and compacted clay liner. The results show that the 100-year mass flux of benzene at the bottom of the composite liner is 45 times higher than that of acetone for the same composite liner. The half-life of the contaminant has a great influence on the solute flux of benzene diffused into the underlying aquifer. Results also indicates that an additional 2.9-5.0 m of the conventional (untreated) compacted clay liner under the geomembrane is required to achieve the same level of protection as provided by 0.60 m of the Hexadecyltrimethylammonium (HDTMA)-treated compacted clay liners in conjunction with the geomembrane. Applications of the solution are also presented in the context of a contaminated two-layered media to demonstrate that different boundary and initial conditions can greatly affect the decontamination rate of the problem. The method is relatively simple to apply and can be used for performing equivalency analysis of landfill liners, preliminary design of groundwater remediation system, evaluating experimental results, and verifying more complex numerical models.

  11. Asymptotic behavior of solutions to nonlinear parabolic equation with nonlinear boundary conditions

    Directory of Open Access Journals (Sweden)

    Diabate Nabongo

    2008-01-01

    Full Text Available We show that solutions of a nonlinear parabolic equation of second order with nonlinear boundary conditions approach zero as t approaches infinity. Also, under additional assumptions, the solutions behave as a function determined here.

  12. On similarity and pseudo-similarity solutions of Falkner-Skan boundary layers

    CERN Document Server

    Guedda, Mohamed

    2008-01-01

    The present work deals with the two-dimensional incompressible,laminar, steady-state boundary layer equations. First, we determinea family of velocity distributions outside the boundary layer suchthat these problems may have similarity solutions. Then, we examenin detail new exact solutions, called Pseudo--similarity, where the external velocity varies inversely-linear with the distance along the surface $ (U_e(x) = U_\\infty x^{-1}). The present work deals with the two-dimensional incompressible, laminar, steady-state boundary layer equations. First, we determine a family of velocity distributions outside the boundary layer such that these problems may have similarity solutions. Then, we examenin detail new exact solutions. The analysis shows that solutions exist only for a lateral suction. For specified conditions, we establish the existence of an infinite number of solutions, including monotonic solutions and solutions which oscillate an infinite number of times and tend to a certain limit. The properties o...

  13. Approximate analytical solutions to the condensation-coagulation equation of aerosols

    CERN Document Server

    Smith, Naftali; Svensmark, Henrik

    2015-01-01

    We present analytical solutions to the steady state injection-condensation-coagulation equation of aerosols in the atmosphere. These solutions are appropriate under different limits but more general than previously derived analytical solutions. For example, we provide an analytic solution to the coagulation limit plus a condensation correction. Our solutions are then compared with numerical results. We show that the solutions can be used to estimate the sensitivity of the cloud condensation nuclei number density to the nucleation rate of small condensation nuclei and to changes in the formation rate of sulfuric acid.

  14. Solutions to a hyperbolic system of conservation laws on two boundaries

    Institute of Scientific and Technical Information of China (English)

    JIA Zhi; YAO Ai-di

    2009-01-01

    This paper studies the interaction of elementary waves including delta-shock waves on two boundaries for a hyperbolic system of conservation laws. The solutions of the initial-boundary value problem for the system are constructively obtained. In the problem the initial-boundary data are in piecewise constant states.

  15. Solution of Moving Boundary Space-Time Fractional Burger’s Equation

    Directory of Open Access Journals (Sweden)

    E. A.-B. Abdel-Salam

    2014-01-01

    Full Text Available The fractional Riccati expansion method is used to solve fractional differential equations with variable coefficients. To illustrate the effectiveness of the method, the moving boundary space-time fractional Burger’s equation is studied. The obtained solutions include generalized trigonometric and hyperbolic function solutions. Among these solutions, some are found for the first time. The linear and periodic moving boundaries for the kink solution of the Burger’s equation are presented graphically and discussed.

  16. The Solution of A Compound Periodic Boundary Problem

    Institute of Scientific and Technical Information of China (English)

    ZHU Jun-ming; DU Jin-yuan

    2005-01-01

    We have studied the compound periodic boundary problem in the upper half plane above the real axis. Under proper conditions, we obtain a periodic and sectionally holomorphic function in the upper half plane. In addition, we have also solved the compound boundary problem with discontinuities of the first kind of the coefficients in the Hilbert condition.

  17. Analytical solution of a model for complex food webs

    OpenAIRE

    Camacho Castro, Juan; Guimerà, Roger; Amaral, Luís A. Nunes

    2002-01-01

    We investigate numerically and analytically a recently proposed model for food webs [Nature {\\bf 404}, 180 (2000)] in the limit of large web sizes and sparse interaction matrices. We obtain analytical expressions for several quantities with ecological interest, in particular the probability distributions for the number of prey and the number of predators. We find that these distributions have fast-decaying exponential and Gaussian tails, respectively. We also find that our analytical expressi...

  18. An analytical model for dispersion of material in the atmospheric planetary boundary layer in presence of precipitation

    International Nuclear Information System (INIS)

    An analytical model for the dispersion of particulates and finely divided material released into the atmosphere near the ground is presented. The possible precipitation when the particles are dense enough and large enough to have deposition velocity, is taken into consideration. The model is derived analytically in the mixing layer or Ekman boundary layer where the mixing process is a direct consequence of turbulent and convective motions generated in the boundary layer. (author)

  19. Existence of Solutions of Periodic Boundary Value Problems for Impulsive Functional Duffing Equations at Nonresonance Case

    Directory of Open Access Journals (Sweden)

    Liu Yuji

    2008-01-01

    Full Text Available Abstract This paper deals with the existence of solutions of the periodic boundary value problem of the impulsive Duffing equations: . Sufficient conditions are established for the existence of at least one solution of above-mentioned boundary value problem. Our method is based upon Schaeffer's fixed-point theorem. Examples are presented to illustrate the efficiency of the obtained results.

  20. Grain boundary structure and solute segregation in titanium-doped sapphire bicrystals

    OpenAIRE

    Taylor, Seth T.

    2002-01-01

    Solute segregation to ceramic grain boundaries governs material processing and microstructure evolution, and can strongly influence material properties critical to engineering performance. Understanding the evolution and implications of grain boundary chemistry is a vital component in the greater effort to engineer ceramics with controlled microstructures. This study examines solute segregation to engineered grain boundaries in titanium-doped sapphire (Al2O3) bicrystals, and explores re...

  1. Debye potentials, electromagnetic reciprocity and impedance boundary conditions for efficient analytic approximation of coupling impedances in complex heterogeneous accelerator pipes

    Energy Technology Data Exchange (ETDEWEB)

    Petracca, S. [Salerno Univ. (Italy)

    1996-08-01

    Debye potentials, the Lorentz reciprocity theorem, and (extended) Leontovich boundary conditions can be used to obtain simple and accurate analytic estimates of the longitudinal and transverse coupling impedances of (piecewise longitudinally uniform) multi-layered pipes with non simple transverse geometry and/or (spatially inhomogeneous) boundary conditions. (author)

  2. On analytical solutions for the nonlinear diffusion equation

    Directory of Open Access Journals (Sweden)

    Ulrich Olivier Dangui-Mbani

    2014-09-01

    Full Text Available The nonlinear diffusion equation arises in many important areas of nonlinear problems of heat and mass transfer, biological systems and processes involving fluid flow and most of the known exact solutions turn out to be approximate solutions in the form of a series which is the exact solution in the closed form. The approximate results obtained by using Homotopy perturbation transform method (HPTM and have been compared with the exact solutions by using software “mathematica” to show the stability of the solutions of nonlinear equation. The comparisons indicate that there is a very good agreement between the HPTM solutions and exact solutions in terms of accuracy

  3. Analytic Solution for Magnetohydrodynamic Stagnation Point Flow towards a Stretching Sheet

    Institute of Scientific and Technical Information of China (English)

    DING Qi; ZHANG Hong-Qing

    2009-01-01

    A steady two-dimensional magnetohydrodynamic stagnation point flow towards a stretching sheet with variable surface temperature is investigated. The analytic solution is obtained by homotopy analysis method. Theconvergence region is computed and the feature of the solution is discussed.

  4. Positive Solutions of Singular Boundary Value Problem of Negative Exponent Emden–Fowler Equation

    Indian Academy of Sciences (India)

    Yuxia Wang; Xiyu Liu

    2003-05-01

    This paper investigates the existence of positive solutions of a singular boundary value problem with negative exponent similar to standard Emden–Fowler equation. A necessary and sufficient condition for the existence of [0, 1] positive solutions as well as 1[0, 1] positive solutions is given by means of the method of lower and upper solutions with the Schauder fixed point theorem.

  5. On analytic solutions of wave equations in regular coordinate systems on Schwarzschild background

    CERN Document Server

    Philipp, Dennis

    2015-01-01

    The propagation of (massless) scalar, electromagnetic and gravitational waves on fixed Schwarzschild background spacetime is described by the general time-dependent Regge-Wheeler equation. We transform this wave equation to usual Schwarzschild, Eddington-Finkelstein, Painleve-Gullstrand and Kruskal-Szekeres coordinates. In the first three cases, but not in the last one, it is possible to separate a harmonic time-dependence. Then the resulting radial equations belong to the class of confluent Heun equations, i.e., we can identify one irregular and two regular singularities. Using the generalized Riemann scheme we collect properties of all the singular points and construct analytic (local) solutions in terms of the standard confluent Heun function HeunC, Frobenius and asymptotic Thome series. We study the Eddington-Finkelstein case in detail and obtain a solution that is regular at the black hole horizon. This solution satisfies causal boundary conditions, i.e., it describes purely ingoing radiation at $r=2M$. ...

  6. On the Assessment of Acoustic Scattering and Shielding by Time Domain Boundary Integral Equation Solutions

    Science.gov (United States)

    Hu, Fang Q.; Pizzo, Michelle E.; Nark, Douglas M.

    2016-01-01

    Based on the time domain boundary integral equation formulation of the linear convective wave equation, a computational tool dubbed Time Domain Fast Acoustic Scattering Toolkit (TD-FAST) has recently been under development. The time domain approach has a distinct advantage that the solutions at all frequencies are obtained in a single computation. In this paper, the formulation of the integral equation, as well as its stabilization by the Burton-Miller type reformulation, is extended to cases of a constant mean flow in an arbitrary direction. In addition, a "Source Surface" is also introduced in the formulation that can be employed to encapsulate regions of noise sources and to facilitate coupling with CFD simulations. This is particularly useful for applications where the noise sources are not easily described by analytical source terms. Numerical examples are presented to assess the accuracy of the formulation, including a computation of noise shielding by a thin barrier motivated by recent Historical Baseline F31A31 open rotor noise shielding experiments. Furthermore, spatial resolution requirements of the time domain boundary element method are also assessed using point per wavelength metrics. It is found that, using only constant basis functions and high-order quadrature for surface integration, relative errors of less than 2% may be obtained when the surface spatial resolution is 5 points-per-wavelength (PPW) or 25 points-per-wavelength squared (PPW2).

  7. Analytical mechanics solutions to problems in classical physics

    CERN Document Server

    Merches, Ioan

    2014-01-01

    Fundamentals of Analytical Mechanics Constraints Classification Criteria for Constraints The Fundamental Dynamical Problem for a Constrained Particle System of Particles Subject to Constraints Lagrange Equations of the First KindElementary Displacements Generalities Real, Possible and Virtual Displacements Virtual Work and Connected Principles Principle of Virtual WorkPrinciple of Virtual Velocities Torricelli's Principle Principles of Analytical Mechanics D'alembert's Principle Configuration Space Generalized Forces Hamilton's Principle The Simple Pendulum Problem Classical (Newtonian) Formal

  8. Grain-boundary migration in nonstoichiometric solid solutions of magnesium aluminate spinel 2

    International Nuclear Information System (INIS)

    The grain-boundary chemistry of magnesium aluminate spinel solid solutions MgO · nAl2O3 has been investigated in order to understand the mechanism of grain-boundary migration. It is found that although segregation of impurity Ca and Si is common, much larger deviations in grain-boundary stoichiometry are present. There is an excess of Al and O relative to Mg at grain boundaries in all compositions. Grain-boundary migration appears to be rate-limited by solute drag from intrinsic defects accommodating lattice nonstoichiometry, rather than by extrinsic solutes, consistent with the observed impurity tolerance of grain-boundary mobility. Different rate-limiting defects are proposed for magnesia-rich and alumina-rich spinels

  9. Exact analytical solutions for contaminant transport in rivers 1. The equilibrium advection-dispersion equation

    Science.gov (United States)

    Analytical solutions of the advection-dispersion equation and related models are indispensable for predicting or analyzing contaminant transport processes in streams and rivers, as well as in other surface water bodies. Many useful analytical solutions originated in disciplines other than surface-w...

  10. Analytic solution for bending-compression/tension members with different moduli

    International Nuclear Information System (INIS)

    In this paper, based on elastic theory of different tension-compression moduli, formulas for calculation of stress and displacement are obtained for bending-compression/tension members under complex stress and subject to combined loadings. An example is given and the obtained analytical solution is compared with numerical results, showing high accuracy of the obtained analytic solution

  11. Analytical Modeling of the Pseudo-Colloid Migration with the Band release Boundary Condition in the Fractured Porous Media

    International Nuclear Information System (INIS)

    Many papers have already dealt with the problem of the radionuclide transport in various fractured porous systems, but without discussing daughter products. However, natural radionuclides may decay to radioactive daughter muscled, which may travel farther than the the parent nuclides. It is considered the multi-member decay chain of the actinide nuclide with the band release inlet boundary condition in a fractured porous rock. In this paper, it is developed the pseudo-colloid migration with the band release inlet boundary conditions with multi-member decay chains in a fractured porous matrix. It is obtained a semi-analytical solution for the multi-member decay chains as a canonical form. As one can expected, the colloid has significantly important influence to the radionuclide transport in the geologic system and the decay chain also isn't neglecting. The concept of deep geological disposal of high-level radioactive waste has been widely accepted at many countries. The repositories aim mainly to prevent the radionuclides form migrating to the biosphere through any one of many pathways. Fractures can act as main pathways for radionuclide transport because of their relatively high permeabilities

  12. Numerical solution to an electromagnetic model with Neumann boundary conditions, for a microwave-driven plasma reactor

    International Nuclear Information System (INIS)

    This work deals with the two-dimensional electromagnetic modelling of a microwave-driven plasma reactor, operated by an axial injection torch (AIT). The model solves Maxwell's equations, which are discretized using a finite difference scheme within staggered grids, adopting a time-harmonic description at fixed 2.45 GHz excitation frequency. The study focuses upon azimuthal axis-symmetric situations, which can be described by a single second-order Helmholtz-type differential equation for the transverse magnetic field. Perfect-conductor boundary conditions are imposed at metal walls, corresponding to zero derivatives for the magnetic field. In situations where convergence requires a more restrictive framework, these Neumann boundary conditions are better replaced by equivalent Dirichlet conditions, whose boundary values depend on the problem solution. Here, we propose a simple numerical algorithm to manage these situations, by tailoring the Dirichlet boundary values to satisfy the physical Neumann conditions. The algorithm is applied to an air-filled circular wave-guide (as a test system) and to the AIT-reactor device (in the presence of plasma). Solution benchmarking checks its accuracy with respect to the corresponding analytical solution (for the circular wave-guide), and analyses its numerical precision by using different integral expressions to calculate the power transmission coefficient (for the AIT-reactor). Results show a 99% accuracy and precision errors lower than 0.1%, for a mesh with 104 grid points.

  13. Algorithms and analytical solutions for rapidly approximating long-term dispersion from line and area sources

    Science.gov (United States)

    Barrett, Steven R. H.; Britter, Rex E.

    Predicting long-term mean pollutant concentrations in the vicinity of airports, roads and other industrial sources are frequently of concern in regulatory and public health contexts. Many emissions are represented geometrically as ground-level line or area sources. Well developed modelling tools such as AERMOD and ADMS are able to model dispersion from finite (i.e. non-point) sources with considerable accuracy, drawing upon an up-to-date understanding of boundary layer behaviour. Due to mathematical difficulties associated with line and area sources, computationally expensive numerical integration schemes have been developed. For example, some models decompose area sources into a large number of line sources orthogonal to the mean wind direction, for which an analytical (Gaussian) solution exists. Models also employ a time-series approach, which involves computing mean pollutant concentrations for every hour over one or more years of meteorological data. This can give rise to computer runtimes of several days for assessment of a site. While this may be acceptable for assessment of a single industrial complex, airport, etc., this level of computational cost precludes national or international policy assessments at the level of detail available with dispersion modelling. In this paper, we extend previous work [S.R.H. Barrett, R.E. Britter, 2008. Development of algorithms and approximations for rapid operational air quality modelling. Atmospheric Environment 42 (2008) 8105-8111] to line and area sources. We introduce approximations which allow for the development of new analytical solutions for long-term mean dispersion from line and area sources, based on hypergeometric functions. We describe how these solutions can be parameterized from a single point source run from an existing advanced dispersion model, thereby accounting for all processes modelled in the more costly algorithms. The parameterization method combined with the analytical solutions for long-term mean

  14. Simplified analytical solutions and numerical computation of one and two-dimensional circular fins with contact conductance and end cooling

    Science.gov (United States)

    Yovanovich, M. M.; Culham, J. R.; Lemczyk, T. F.

    1986-01-01

    One and two-dimensional solutions are obtained for annular fins of constant cross-section having uniform base, end and side conductances. The solutions are dependent upon one geometric parameter and three fin parameters which relate the internal conductive resistance to the three boundary resistances. The two and one-dimensional solutions are compared by means of the heat flow rate or fin efficiency ratios. Simple polynomials are developed for fast, accurate numerical computation of the modified Bessel functions which appear in the solutions. For annular fins used in typical microelectronic applications the analytical expressions are also reduced to alternate expressions which are shown to be expressible by means of simple polynomials which converge to unity for large values of the arguments. Numerical computations were performed on an IBM-PC and some typical results are reported in graphical form. These plots give the heat loss ratio as a function of the dimensionless geometric and fin parameters.

  15. An analytical solution for quantum size effects on Seebeck coefficient

    Science.gov (United States)

    Karabetoglu, S.; Sisman, A.; Ozturk, Z. F.

    2016-03-01

    There are numerous experimental and numerical studies about quantum size effects on Seebeck coefficient. In contrast, in this study, we obtain analytical expressions for Seebeck coefficient under quantum size effects. Seebeck coefficient of a Fermi gas confined in a rectangular domain is considered. Analytical expressions, which represent the size dependency of Seebeck coefficient explicitly, are derived in terms of confinement parameters. A fundamental form of Seebeck coefficient based on infinite summations is used under relaxation time approximation. To obtain analytical results, summations are calculated using the first two terms of Poisson summation formula. It is shown that they are in good agreement with the exact results based on direct calculation of summations as long as confinement parameters are less than unity. The analytical results are also in good agreement with experimental and numerical ones in literature. Maximum relative errors of analytical expressions are less than 3% and 4% for 2D and 1D cases, respectively. Dimensional transitions of Seebeck coefficient are also examined. Furthermore, a detailed physical explanation for the oscillations in Seebeck coefficient is proposed by considering the relative standard deviation of total variance of particle number in Fermi shell.

  16. Approximate Analytic Solutions of Transient Nonlinear Heat Conduction with Temperature-Dependent Thermal Diffusivity

    Directory of Open Access Journals (Sweden)

    M. T. Mustafa

    2014-01-01

    Full Text Available A new approach for generating approximate analytic solutions of transient nonlinear heat conduction problems is presented. It is based on an effective combination of Lie symmetry method, homotopy perturbation method, finite element method, and simulation based error reduction techniques. Implementation of the proposed approach is demonstrated by applying it to determine approximate analytic solutions of real life problems consisting of transient nonlinear heat conduction in semi-infinite bars made of stainless steel AISI 304 and mild steel. The results from the approximate analytical solutions and the numerical solution are compared indicating good agreement.

  17. Solute segregation on Σ3 and random grain boundaries in type 316L stainless steel

    International Nuclear Information System (INIS)

    Solute segregation and impurity segregation on random and Σ3 grain boundaries in a type 316L stainless steel were investigated by means of atom probe tomography (APT). Segregation of Mo, P, B, and C was observed on random grain boundaries, irrespective of grain boundary misorientation. Two-dimensional concentration maps along the grain boundary plane revealed that the concentrations of all segregated elements were not homogeneous and no co-segregation was observed. In contrast, no segregation was observed on Σ3 grain boundaries

  18. SUPORT, Solution of Linear 2 Point Boundary Value Problems, Runge-Kutta-Fehlberg Method

    International Nuclear Information System (INIS)

    1 - Description of problem or function: SUPORT solves a system of linear two-point boundary-value problems subject to general separated boundary conditions. 2 - Method of solution: The method of solution uses superposition coupled with an ortho-normalization procedure and a variable-step Runge-Kutta-Fehlberg integration scheme. Each time the superposition solutions start to lose their numerical independence, the vectors are re-ortho-normalized before integration proceeds. The underlying principle of the algorithm is then to piece together the intermediate (orthogonalized) solutions, defined on the various subintervals, to obtain the desired solution. 3 - Restrictions on the complexity of the problem: The boundary-value problem must be linear and the boundary conditions must be separated. The number of equations which can be solved is dependent upon the main storage available

  19. Analytical solution of population balance equation involving aggregation and breakage in terms of auxiliary equation method

    Indian Academy of Sciences (India)

    Zehra Pinar; Abhishek Dutta; Guido Bény; Turgut Öziş

    2015-01-01

    This paper presents an effective analytical simulation to solve population balance equation (PBE), involving particulate aggregation and breakage, by making use of appropriate solution(s) of associated complementary equation via auxiliary equation method (AEM). Travelling wave solutions of the complementary equation of a nonlinear PBE with appropriately chosen parameters is taken to be analogous to the description of the dynamic behaviour of the particulate processes. For an initial proof-of-concept, a general case when the number of particles varies with respect to time is chosen. Three cases, i.e. (1) balanced aggregation and breakage, (2) when aggregation can dominate and (3) breakage can dominate, are selected and solved for their corresponding analytical solutions. The results are then compared with the available analytical solution, based on Laplace transform obtained from literature. In this communication, it is shown that the solution approach proposed via AEM is flexible and therefore more efficient than the analytical approach used in the literature.

  20. Analytical Solution of the Hyperbolic Heat Conduction Equation for Moving Semi-Infinite Medium under the Effect of Time-Dependent Laser Heat Source

    Directory of Open Access Journals (Sweden)

    R. T. Al-Khairy

    2009-01-01

    source, whose capacity is given by (,=((1−− while the semi-infinite body has insulated boundary. The solution is obtained by Laplace transforms method, and the discussion of solutions for different time characteristics of heat sources capacity (constant, instantaneous, and exponential is presented. The effect of absorption coefficients on the temperature profiles is examined in detail. It is found that the closed form solution derived from the present study reduces to the previously obtained analytical solution when the medium velocity is set to zero in the closed form solution.

  1. Two analytic methods applied to radiative transfer in the linear-anisotropic scattering medium with graded index and diffuse gray boundaries

    International Nuclear Information System (INIS)

    The curved ray-tracing method is extended to radiative transfer in the graded index medium with diffuse gray boundary conditions instead of black boundary conditions and the pseudo-source adding method is extended to the case of the linear-anisotropic scattering medium with graded index from non-scattering medium. Furthermore, the equivalence of the two methods is verified by formulation derivation. As exact analytical solutions, both the methods have high accuracy and fast computational speed. The predicted temperature distributions and dimensionless radiative heat flux at radiative equilibrium are determined by the proposed methods, and the numerical results are compared with the data in references. The results show that the present methods have a good accuracy. Influences of various combinations of refractive index and boundary emissivities on the temperature distributions and dimensionless radiative heat flux are also investigated.

  2. On analytical solution of the Navier-Stokes equations

    International Nuclear Information System (INIS)

    An analytical method for solving the dissipative, nonlinear and non-stationary Navier-Stokes equations is presented. Velocity and pressure is expanded in power series of cartesian coordinates and time. The method is applied to 2-D incompressible gravitational flow in a bounded, rectangular domain

  3. Analytic solution for a class of turbulence problems

    OpenAIRE

    Vlad, M.; Spineanu, F.; Misguich, J. H.; Balescu, R.

    2001-01-01

    An exact analytical method for determining the Lagrangian velocity correlation and the diffusion coefficient for particles moving in a stochastic velocity field is derived. It applies to divergence-free 2-dimensional Gaussian stochastic fields which are stationary, homogeneous and have factorized Eulerian correlations.

  4. Stability of Solutions to a Free Boundary Problem for Tumor Growth

    OpenAIRE

    Shihe Xu

    2014-01-01

    We study the asymptotic behaviour of quasi-stationary solutions of a free boundary problem which had been discussed by Bueno (2005). Using a simpler method we prove that the quasi-steady solutions of the problem converge uniformly to the unique nontrivial steady solution.

  5. Analytical solution based on stream-aquifer interactions in partially penetrating streams

    Directory of Open Access Journals (Sweden)

    Yong Huang

    2010-09-01

    Full Text Available An analytical solution of drawdown caused by pumping is developed in an aquifer hydraulically connected to a finite-width stream on the condition of two streams. The proposed analytical solution modified Hunt’s analytical solution and not only considers the effect of stream width on drawdown, but also takes the distribution of drawdown on the interaction of two streams into account. Advantages of the solution include its simple structure, consisting of the Theis well function, parameters of aquifer and streambed semipervious material. The calculated results show that the proposed analytical solution agrees well with the previous solution and the errors between the two solutions are equal to zero on the condition of a stream without considering the effect of stream width. Also, deviations between the two analytical solutions increase with the increase of stream width. Furthermore, four cases are studied to discuss the effect of two streams on drawdown. It assumes that some parameters are changeable, and other parameters are constant, such as stream width, the distance between stream and pumping well, stream recharge rate, and the leakance coefficient of streambed semipervious material, etc. The analytical solution may provide estimates for parameters of aquifer and streambed semipervious material using the Type Curve Method through the data of field test.

  6. Numerical solution of 2D flows in atmospheric boundary layer

    Czech Academy of Sciences Publication Activity Database

    Šimonek, J.; Tauer, J.; Kozel, K.; Jaňour, Zbyněk; Příhoda, Jaromír

    Praha : Ústav termomechaniky AV ČR, v. v. i., 2008 - (Jonáš, P.; Uruba, V.), s. 51-52 ISBN 978-80-87012-14-7. [Colloquium FLUID DYNAMICS 2008. Praha (CZ), 22.10.2008-24.10.2008] R&D Projects: GA AV ČR 1ET400760405 Institutional research plan: CEZ:AV0Z20760514 Keywords : numerical simulation * atmospheric boundary layer * stratified flow Subject RIV: BK - Fluid Dynamics

  7. Existence of Positive Solutions for Higher Order Boundary Value Problem on Time Scales

    Institute of Scientific and Technical Information of China (English)

    XIE DA-PENG; LIU YANG; SUN MING-ZHE; Li Yong

    2013-01-01

    In this paper,we investigate the existence of positive solutions of a class higher order boundary value problems on time scales.The class of boundary value problems educes a four-point (or three-point or two-point) boundary value problems,for which some similar results are established.Our approach relies on the Krasnosel'skii fixed point theorem.The result of this paper is new and extends previously known results.

  8. Explicit analytical solutions of the anisotropic Brinkman model for the natural convection in porous media (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    CAI; Ruixian; GOU; Chenhua; ZHANG; Na

    2005-01-01

    Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model―an improved Darcy model―describing the natural convection in porous media. Besides their important theoretical meaning (for example, in analyzing the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions that can promote the development of computational heat and mass transfer. Some solutions considering the anisotropic effect of permeability have been given previously by the authors, and this paper gives solutions including the anisotropic effect of thermal conductivity and the effect of heat sources.

  9. Analytic Solution of Strongly Coupling Schr(o)dinger Equations

    Institute of Scientific and Technical Information of China (English)

    LIAO Jin-Feng; ZHUANG Peng-Fei

    2004-01-01

    A recently developed expansion method for analytically solving the ground states of strongly coupling Schrodinger equations by Friedberg,Lee,and Zhao is extended to excited states and applied to power-law central forces for which scaling properties are proposed.As examples for application of the extended method,the Hydrogen atom problem is resolved and the low-lying states of Yukawa potential are approximately obtained.

  10. Positive solutions and singular discrete boundary value problems

    Czech Academy of Sciences Publication Activity Database

    Cecchi, M.; Došlá, Zuzana; Marini, M.

    2004-01-01

    Roč. 4, - (2004), s. 271-283. ISSN 1085-3375 Institutional research plan: CEZ:AV0Z1019905 Keywords : second - order nonlinear difference equation * singular nonlinearities * decaying solution Subject RIV: BA - General Mathematics

  11. Analytical solutions of the electrostatically actuated curled beam problem

    KAUST Repository

    Younis, Mohammad I.

    2014-07-24

    This works presents analytical expressions of the electrostatically actuated initially deformed cantilever beam problem. The formulation is based on the continuous Euler-Bernoulli beam model combined with a single-mode Galerkin approximation. We derive simple analytical expressions for two commonly observed deformed beams configurations: the curled and tilted configurations. The derived analytical formulas are validated by comparing their results to experimental data and numerical results of a multi-mode reduced order model. The derived expressions do not involve any complicated integrals or complex terms and can be conveniently used by designers for quick, yet accurate, estimations. The formulas are found to yield accurate results for most commonly encountered microbeams of initial tip deflections of few microns. For largely deformed beams, we found that these formulas yield less accurate results due to the limitations of the single-mode approximation. In such cases, multi-mode reduced order models are shown to yield accurate results. © 2014 Springer-Verlag Berlin Heidelberg.

  12. Existence of Solutions for Nonlinear Four-Point -Laplacian Boundary Value Problems on Time Scales

    Directory of Open Access Journals (Sweden)

    Topal SGulsan

    2009-01-01

    Full Text Available We are concerned with proving the existence of positive solutions of a nonlinear second-order four-point boundary value problem with a -Laplacian operator on time scales. The proofs are based on the fixed point theorems concerning cones in a Banach space. Existence result for -Laplacian boundary value problem is also given by the monotone method.

  13. Bethe ansatz solution of the open XX spin chain with non-diagonal boundary terms

    International Nuclear Information System (INIS)

    We consider the integrable open XX quantum spin chain with non-diagonal boundary terms. We derive an exact inversion identity, by which we obtain the eigenvalues of the transfer matrix and the Bethe ansatz equations. For generic values of the boundary parameters, the Bethe ansatz solution is formulated in terms of the Jacobian elliptic functions. (author)

  14. Existence of three positive solutions for boundary value problem with fractional order and infinite delay

    Directory of Open Access Journals (Sweden)

    Benaouda Hedia

    2015-07-01

    Full Text Available In this paper we investigate the existence three positives solutions by using Leggett-Williams fixed point theorem in cones for three boundary value problem with fractional order and infinite delay.

  15. An Overview of the Lower and Upper Solutions Method with Nonlinear Boundary Value Conditions

    Directory of Open Access Journals (Sweden)

    Cabada Alberto

    2011-01-01

    Full Text Available The aim of this paper is to point out recent and classical results related with the existence of solutions of second-order problems coupled with nonlinear boundary value conditions.

  16. A Global Description of the Positive Solutions of Sublinear Second-Order Discrete Boundary Value Problems

    OpenAIRE

    Ma Ruyun; Xu Youji; Gao Chenghua

    2009-01-01

    Let be an integer with , , . We consider boundary value problems of nonlinear second-order difference equations of the form , , , where , and, for , and , , . We investigate the global structure of positive solutions by using the Rabinowitz's global bifurcation theorem.

  17. Electron irradiation induced solute segregation near grain boundaries in austenitic stainless steel

    International Nuclear Information System (INIS)

    Radiation-induced solute segregation near internal defect sinks such as high angle grain boundaries was investigated, through the interaction between point defects and solute atom in austenitic stainless steel and its model alloys. Electron irradiation was performed in a high voltage electron microscope (H V E M) at a dose rate of about 2 multiple 10-3 d p a.S-1 at a temperature range of 350-600 degree C. Solute concentration profile near grain boundaries was measured by E D X in S T E M mode. Strong enrichment and depletion of solutes were observed on grain boundaries during irradiation and segregation rate went through a maximum at 450 degree C. These facts indicate that grain boundaries act as preferential sinks for radiation-induced point defects

  18. Periodic solutions of a non-linear wave equation with homogeneous boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Rudakov, I A [M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2006-02-28

    We prove the existence of time-periodic solutions of a non-linear wave equation with homogeneous boundary conditions. The non-linear term either has polynomial growth or satisfies a 'non-resonance' condition.

  19. Positive solutions for a third-order three-point boundary-value problem

    OpenAIRE

    Torres, Francisco J.

    2013-01-01

    In this article, we study the existence of positive solutions to a nonlinear third-order three point boundary value problem. The main tools are Krasnosel'skii fixed point theorem on cones, and the fixed point index theory.

  20. LIMIT BEHAVIOUR OF SOLUTIONS TO EQUIVALUED SURFACE BOUNDARY VALUE PROBLEM FOR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    LiFengquan

    2002-01-01

    In this paper,we discuss the limit behaviour of solutions to equivalued surface boundayr value problem for parabolic equatiopns when the equivalued surface boundary shriks to a point and the space dimension of the domain is two or more.

  1. Existence and uniqueness of solutions for a Neumann boundary-value problem

    Directory of Open Access Journals (Sweden)

    Safia Benmansour

    2011-09-01

    Full Text Available In this article, we show the existence and uniqueness of positive solutions for perturbed Neumann boundary-value problems of second-order differential equations. We use a fixed point theorem for general $alpha$-concave operators.

  2. Existence of Three Positive Solutions to Some p-Laplacian Boundary Value Problems

    Directory of Open Access Journals (Sweden)

    Moulay Rchid Sidi Ammi

    2013-01-01

    Full Text Available We obtain, by using the Leggett-Williams fixed point theorem, sufficient conditions that ensure the existence of at least three positive solutions to some p-Laplacian boundary value problems on time scales.

  3. Closed form solution to a second order boundary value problem and its application in fluid mechanics

    International Nuclear Information System (INIS)

    The Adomian decomposition method is used by many researchers to investigate several scientific models. In this Letter, the modified Adomian decomposition method is applied to construct a closed form solution for a second order boundary value problem with singularity

  4. Analytical solutions of simply supported magnetoelectroelastic circular plate under uniform loads

    Institute of Scientific and Technical Information of China (English)

    陈江瑛; 丁皓江; 侯鹏飞

    2003-01-01

    In this paper, the axisymmetric general solutions of transversely isotropic magnetoelectroelastic media are expressed with four harmonic displacement functions at first. Then, based on the solutions, the analytical three-dimensional solutions are provided for a simply supported magnetoelectroelastic circular plate subjected to uniform loads. Finally, the example of circular plate is presented.

  5. Analytical Solution of a Tapering Cable Equation for Dendrites and Conformal Symmetry

    Science.gov (United States)

    Romero, Juan M.; Trenado, Carlos

    2015-09-01

    Progress towards detailed characterization of structural and biophysical properties of dendrites emphasizes the importance of finding analytical solutions for more realistic dendrite models with circular cross-section and varying diameter. In this regard, we employ symmetry methods and the passive cable theory to deduce a generalized analytical solution for electric propagation in a family of tapering dendrites. In particular, we study the effect of such tapering geometries on the obtained electric voltage. Simulations using the deduced analytical solution indicate that for a subfamily of tapering profiles neural integration is better than in the stereotypical profile given by a cylinder.

  6. Mathematical apparatus for boundary value problems in gravity field studies and the geometry of the solution domain

    Science.gov (United States)

    Holota, Petr; Nesvadba, Otakar

    2014-05-01

    In geodesy mathematical techniques for gravity field studies that rest on the concept of the so-called classical solution of boundary value problems, have a rather traditional position. Nevertheless, the range of the tools for treating problems in this field is much wider. For instance the concept of the weak solution met with a considerable attention. From this point of view the approach is associated with constructing the respective integral kernels or Green's function in case we consider the classical solution concept or with the choice and constructing basis functions in case we are lucking for the weak solution of the problem. Within the tools considered we discuss also the use of reproducing kernels. In both the cases (classical or weak) the construction of the apparatus above represents and important technical step. It is not elementary, but for a number of fundamental boundary value problems the solution is known, in particular in the case of a spherical solution domain. The sphere, however, is rather far from the real shape of the Earth, which is interpreted here in terms of a functional analytic norm. The distance has a negative effect on any attempt to reach the solution of the boundary value problems considered (and to bridge the departure of the Earth's surface from the sphere) by an iteration procedure based on a successive application of a solution technique developed for the spherical boundary. From this point of view the construction of the integral kernels and basis functions for an oblate ellipsoid of revolution means a step closer towards reality. In this contribution we on the one hand give an overview of the results already achieved and subsequently develop the topic. The summation of series of ellipsoidal harmonics is one of the key problems in this connection. Hypergeometric functions and series are applied too. We also show where the use of Legendre elliptic integrals adds to the solution of the problem. It is interesting that they do not

  7. Explicit construction of solutions to the Burgers equation with discontinuous initial-boundary conditions

    OpenAIRE

    Désilles, Anya; Frankowska, Hélène

    2013-01-01

    International audience Abstract. A solution of the initial-boundary value problem on the strip (0,1) × [0, 1] for scalar conservation laws with strictly convex flux can be obtained by considering gradients of the unique solution V to an associated Hamilton-Jacobi equation (with appropriately defined initial and boundary conditions). It was shown in Frankowska (2010) that V can be expressed as the minimum of three value functions arising in calculus of variations problems that, in turn, can...

  8. Existence of Solutions for p-Laplace Equations Subjected to Neumann Boundary Value Problem

    Institute of Scientific and Technical Information of China (English)

    HU Zhi-gang; RUI Wen-juan; LIU Wen-bing

    2006-01-01

    The existence of solutions for one dimensional p-Laplace equation (φp(u'))'=f(t,u,u') with t∈(0,1) and φp(s)=│s│p-2s,s≠0 subjected to Neumann boundary value problem at u'(0)=0,u'(1)=0. By using the degree theory, the sufficient conditions of the existence of solutions for p-Laplace equation subjected to Neumann boundary value condition are established.

  9. Weak solutions for an initial-boundary Q-Tensor problem related to liquid crystals

    OpenAIRE

    Guillén González, Francisco Manuel; Rodríguez Bellido, María Ángeles

    2015-01-01

    The coupled Navier-Stokes and Q-Tensor system is considered in a bounded three-dimensional domain under homogeneous Dirichlet boundary conditions for the velocity u and either nonhomogeneous Dirichlet or homogeneous Neumann boundary conditions for the tensor Q. The corresponding initial-value problem in the whole space R3 was analyzed in [Paicu & Zarnescu, 2012]. In this paper, three main results concerning weak solutions will be proved; the existence of global in time weak solutions (bounded...

  10. On similarity and pseudo-similarity solutions of Falkner-Skan boundary layers

    OpenAIRE

    Guedda, Mohamed; Hammouch, Zakia

    2006-01-01

    The present work deals with the two-dimensional incompressible,laminar, steady-state boundary layer equations. First, we determinea family of velocity distributions outside the boundary layer suchthat these problems may have similarity solutions. Then, we examenin detail new exact solutions, called Pseudo--similarity, where the external velocity varies inversely-linear with the distance along the surface $ (U_e(x) = U_\\infty x^{-1}). The present work deals with the two-dimensional incompressi...

  11. Global existence and blowup of solutions to a free boundary problem for mutualistic model

    Institute of Scientific and Technical Information of China (English)

    KIM; KwangIk

    2010-01-01

    This article is concerned with a system of semilinear parabolic equations with a free boundary,which arises in a mutualistic ecological model.The local existence and uniqueness of a classical solution are obtained.The asymptotic behavior of the free boundary problem is studied.Our results show that the free problem admits a global slow solution if the inter-specific competitions are strong,while if the inter-specific competitions are weak there exist the blowup solution and global fast solution.

  12. A Semi-Analytical Solution for Elastic Analysis of Rotating Thick Cylindrical Shells with Variable Thickness Using Disk Form Multilayers

    Directory of Open Access Journals (Sweden)

    Mohammad Zamani Nejad

    2014-01-01

    Full Text Available Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT. These equations are in the form of a set of general differential equations. Given that the cylinder is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM is also presented and good agreement was found.

  13. Editorial: Special Issue on Analytical and Approximate Solutions for Numerical Problems

    Directory of Open Access Journals (Sweden)

    Walailak Journal of Science and Technology

    2014-08-01

    Full Text Available Though methods and algorithms in numerical analysis are not new, they have become increasingly popular with the development of high speed computing capabilities. Indeed, the ready availability of high speed modern digital computers and easy-to-employ powerful software packages has had a major impact on science, engineering education and practice in the recent past. Researchers in the past had to depend on analytical skills to solve significant engineering problems but, nowadays, researchers have access to tremendous amount of computation power under their fingertips, and they mostly require understanding the physical nature of the problem and interpreting the results. For some problems, several approximate analytical solutions already exist for simple cases but finding new solution to complex problems by designing and developing novel techniques and algorithms are indeed a great challenging task to give approximate solutions and sufficient accuracy especially for engineering purposes. In particular, it is frequently assumed that deriving an analytical solution for any problem is simpler than obtaining a numerical solution for the same problem. But in most of the cases relationships between numerical and analytical solutions complexities are exactly opposite to each other. In addition, analytical solutions are limited to relatively simple problems while numerical ones can be obtained for complex realistic situations. Indeed, analytical solutions are very useful for testing (benchmarking numerical codes and for understanding principal physical controls of complex processes that are modeled numerically. During the recent past, in order to overcome some numerical difficulties a variety of numerical approaches were introduced, such as the finite difference methods (FDM, the finite element methods (FEM, and other alternative methods. Numerical methods typically include material on such topics as computer precision, root finding techniques, solving

  14. General Analytical Solutions of Scalar Field Cosmology with Arbitrary Potential

    CERN Document Server

    Dimakis, N; Zampeli, Adamantia; Paliathanasis, Andronikos; Christodoulakis, T; Terzis, Petros A

    2016-01-01

    We present the solution space for the case of a minimally coupled scalar field with arbitrary potential in a FLRW metric. This is made possible due to the existence of a nonlocal integral of motion corresponding to the conformal Killing field of the two-dimensional minisuperspace metric. The case for both spatially flat and non flat are studied first in the presence of only the scalar field and subsequently with the addition of non interacting perfect fluids. It is verified that this addition does not change the general form of the solution, but only the particular expressions of the scalar field and the potential. The results are applied in the case of parametric dark energy models where we derive the scalar field equivalence solution for some proposed models in the literature.

  15. Visual analytics : towards intelligent interactive internet and security solutions

    OpenAIRE

    Davey, James; Mansmann, Florian; Kohlhammer, Jörn; Keim, Daniel

    2012-01-01

    In the Future Internet, Big Data can not only be found in the amount of traffic, logs or alerts of the network infrastructure, but also on the content side. While the term Big Data refers to the increase in available data, this implicitly means that we must deal with problems at a larger scale and thus hints at scalability issues in the analysis of such data sets. Visual Analytics is an enabling technology, that offers new ways of extracting information from Big Data through intelligent, inte...

  16. Analytical solution of a system of two coupled Schroedinger equations

    International Nuclear Information System (INIS)

    The problem of solving analytically a system of two coupled Schroedinger equations is examined from the methodological point of view. First, the proof of a theorem on the separability of the equations is given, followed by application to a few examples of interest in physics. Particularly, it will be seen that the exact resonance as well as the constant coupling case are merely special cases of this theorem. When the separation of the equations is not possible, i.e. in the non-resonance case, a new formulation of the problem will be introduced in the frame of a modified resonance distortion approximation

  17. Analytical solution of a stochastic content-based network model

    International Nuclear Information System (INIS)

    We define and completely solve a content-based directed network whose nodes consist of random words and an adjacency rule involving perfect or approximate matches for an alphabet with an arbitrary number of letters. The analytic expression for the out-degree distribution shows a crossover from a leading power law behaviour to a log-periodic regime bounded by a different power law decay. The leading exponents in the two regions have a weak dependence on the mean word length, and an even weaker dependence on the alphabet size. The in-degree distribution, on the other hand, is much narrower and does not show any scaling behaviour

  18. Radiation boundary condition and anisotropy correction for finite difference solutions of the Helmholtz equation

    Science.gov (United States)

    Tam, Christopher K. W.; Webb, Jay C.

    1994-01-01

    In this paper finite-difference solutions of the Helmholtz equation in an open domain are considered. By using a second-order central difference scheme and the Bayliss-Turkel radiation boundary condition, reasonably accurate solutions can be obtained when the number of grid points per acoustic wavelength used is large. However, when a smaller number of grid points per wavelength is used excessive reflections occur which tend to overwhelm the computed solutions. Excessive reflections are due to the incompability between the governing finite difference equation and the Bayliss-Turkel radiation boundary condition. The Bayliss-Turkel radiation boundary condition was developed from the asymptotic solution of the partial differential equation. To obtain compatibility, the radiation boundary condition should be constructed from the asymptotic solution of the finite difference equation instead. Examples are provided using the improved radiation boundary condition based on the asymptotic solution of the governing finite difference equation. The computed results are free of reflections even when only five grid points per wavelength are used. The improved radiation boundary condition has also been tested for problems with complex acoustic sources and sources embedded in a uniform mean flow. The present method of developing a radiation boundary condition is also applicable to higher order finite difference schemes. In all these cases no reflected waves could be detected. The use of finite difference approximation inevita bly introduces anisotropy into the governing field equation. The effect of anisotropy is to distort the directional distribution of the amplitude and phase of the computed solution. It can be quite large when the number of grid points per wavelength used in the computation is small. A way to correct this effect is proposed. The correction factor developed from the asymptotic solutions is source independent and, hence, can be determined once and for all. The

  19. On singular solutions of a magnetohydrodynamic nonlinear boundary layer equation

    Directory of Open Access Journals (Sweden)

    Mohammed Guedda

    2007-05-01

    Full Text Available This paper concerns the singular solutions of the equation $$ f''' +kappa ff''-eta {f'}^2 = 0, $$ where $eta < 0$ and $kappa = 0$ or 1. This equation arises when modelling heat transfer past a vertical flat plate embedded in a saturated porous medium with an applied magnetic field. After suitable normalization, $f'$ represents the velocity parallel to the surface or the non-dimensional fluid temperature. Our interest is in solutions which develop a singularity at some point (the blow-up point. In particular, we shall examine in detail the behavior of $f$ near the blow-up point.

  20. Some Exact Solutions of Boundary Layer Flows along a Vertical Plate with Buoyancy Forces Combined with Lorentz Forces under Uniform Suction

    Directory of Open Access Journals (Sweden)

    Asterios Pantokratoras

    2008-01-01

    Full Text Available Exact analytical solutions of boundary layer flows along a vertical porous plate with uniform suction are derived and presented in this paper. The solutions concern the Blasius, Sakiadis, and Blasius-Sakiadis flows with buoyancy forces combined with either MHD Lorentz or EMHD Lorentz forces. In addition, some exact solutions are presented specifically for water in the temperature range of 0∘C≤≤8∘C, where water density is nearly parabolic. Except for their use as benchmarking means for testing the numerical solution of the Navier-Stokes equations, the presented exact solutions with EMHD forces have use in flow separation control in aeronautics and hydronautics, whereas the MHD results have applications in process metallurgy and fusion technology. These analytical solutions are valid for flows with strong suction.

  1. Solutions of Laplace's equation with simple boundary conditions, and their applications for capacitors with multiple symmetries

    CERN Document Server

    Morales, Mayckol; Herrera, William J

    2015-01-01

    We find solutions of Laplace's equation with specific boundary conditions (in which such solutions take either the value zero or unity in each surface) using a generic curvilinear system of coordinates. Such purely geometrical solutions (that we shall call Basic Harmonic Functions BHF's) are utilized to obtain a more general class of solutions for Laplace's equation, in which the functions take arbitrary constant values on the boundaries. On the other hand, the BHF's are also used to obtain the capacitance of many electrostatic configurations of conductors. This method of finding solutions of Laplace's equation and capacitances with multiple symmetries is particularly simple, owing to the fact that the method of separation of variables becomes much simpler under the boundary conditions that lead to the BHF's. Examples of application in complex symmetries are given. Then, configurations of succesive embedding of conductors are also examined. In addition, expressions for electric fields between two conductors a...

  2. Existence and uniqueness of entropy solution to initial boundary value problem for the inviscid Burgers equation

    CERN Document Server

    Zhu, C

    2003-01-01

    This paper is concerned with the existence and uniqueness of the entropy solution to the initial boundary value problem for the inviscid Burgers equation. To apply the method of vanishing viscosity to study the existence of the entropy solution, we first introduce the initial boundary value problem for the viscous Burgers equation, and as in Evans (1998 Partial Differential Equations (Providence, RI: American Mathematical Society) and Hopf (1950 Commun. Pure Appl. Math. 3 201-30), give the formula of the corresponding viscosity solutions by Hopf-Cole transformation. Secondly, we prove the convergence of the viscosity solution sequences and verify that the limiting function is an entropy solution. Finally, we give an example to show how our main result can be applied to solve the initial boundary value problem for the Burgers equation.

  3. Existence and uniqueness of entropy solution to initial boundary value problem for the inviscid Burgers equation

    International Nuclear Information System (INIS)

    This paper is concerned with the existence and uniqueness of the entropy solution to the initial boundary value problem for the inviscid Burgers equation. To apply the method of vanishing viscosity to study the existence of the entropy solution, we first introduce the initial boundary value problem for the viscous Burgers equation, and as in Evans (1998 Partial Differential Equations (Providence, RI: American Mathematical Society) and Hopf (1950 Commun. Pure Appl. Math. 3 201-30), give the formula of the corresponding viscosity solutions by Hopf-Cole transformation. Secondly, we prove the convergence of the viscosity solution sequences and verify that the limiting function is an entropy solution. Finally, we give an example to show how our main result can be applied to solve the initial boundary value problem for the Burgers equation

  4. Existence and uniqueness of entropy solution to initial boundary value problem for the inviscid Burgers equation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Changjiang; Duan, Renjun [Laboratory of Nonlinear Analysis, Department of Mathematics, Central China Normal University, Wuhan 430079, People' s Republic of China (China)

    2003-02-28

    This paper is concerned with the existence and uniqueness of the entropy solution to the initial boundary value problem for the inviscid Burgers equation. To apply the method of vanishing viscosity to study the existence of the entropy solution, we first introduce the initial boundary value problem for the viscous Burgers equation, and as in Evans (1998 Partial Differential Equations (Providence, RI: American Mathematical Society) and Hopf (1950 Commun. Pure Appl. Math. 3 201-30), give the formula of the corresponding viscosity solutions by Hopf-Cole transformation. Secondly, we prove the convergence of the viscosity solution sequences and verify that the limiting function is an entropy solution. Finally, we give an example to show how our main result can be applied to solve the initial boundary value problem for the Burgers equation.

  5. Second-order boundary estimates for solutions to singular elliptic equations in borderline cases

    Directory of Open Access Journals (Sweden)

    Claudia Anedda

    2011-04-01

    Full Text Available Let $Omegasubset R^N$ be a bounded smooth domain. We investigate the effect of the mean curvature of the boundary $partialOmega$ on the behaviour of the solution to the homogeneous Dirichlet boundary value problem for the equation $Delta u+f(u=0$. Under appropriate growth conditions on $f(t$ as $t$ approaches zero, we find asymptotic expansions up to the second order of the solution in terms of the distance from $x$ to the boundary $partialOmega$.

  6. Analytic solution for relativistic transverse flow at the softest point

    CERN Document Server

    Biro, T S

    2000-01-01

    We obtain an extension of Bjorken's 1+1 dimensional scaling relativistic flow solution to relativistic transverse velocities with cylindrical symmetry in 1+3 dimensions at constant, homogeneous pressure (vanishing sound velocity). This can be the situation during a first order phase transition converting quark matter into hadron matter in relativistic heavy ion collisions.

  7. Development of Analytical Solutions for Quasistationary Electromagnetic Fields for Conducting Spheroids in the Proximity of Current-Carrying Turns

    Science.gov (United States)

    Jayasekara, Nandaka

    Exact analytical solutions for the quasistationary electromagnetic fields in the presence of conducting objects require the field solutions both internal and external to the conductors. Such solutions are limited for certain canonically shaped objects but are useful in testing the accuracy of various approximate models and numerical methods developed to solve complex problems related to real world conducting objects and in calibrating instruments designed to measure various field quantities. Theoretical investigations of quasistationary electromagnetic fields also aid in improving the understanding of the physical phenomena of electromagnetic induction. This thesis presents rigorous analytical expressions derived as benchmark solutions for the quasistationary field quantities both inside and outside, Joule losses and the electromagnetic forces acting upon a conducting spheroid placed in the proximity of a non-uniform field produced by current-carrying turns. These expressions are used to generate numerous numerical results of specified accuracy and selected results are presented in a normalized form for extended ranges of the spheroid axial ratio, the ratio of the depth of penetration to the semi-minor axis and the position of the inducing turns relative to the spheroids. They are intended to constitute reference data to be employed for comprehensive comparisons of results from approximate numerical methods or from boundary impedance models used for real world conductors. Approximate boundary conditions such as the simpler perfect electric conductor model or the Leontovich surface impedance boundary condition model can be used to obtain approximate solutions by only analyzing the field external to the conducting object. The range of validity of these impedance boundary condition models for the analysis of axisymmetric eddy-current problems is thoroughly investigated. While the simpler PEC model can be employed only when the electromagnetic depth of penetration is

  8. RESTRICTED NONLINEAR APPROXIMATION AND SINGULAR SOLUTIONS OF BOUNDARY INTEGRAL EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    Reinhard Hochmuth

    2002-01-01

    This paper studies several problems, which are potentially relevant for the construction of adaptive numerical schemes. First, biorthogonal spline wavelets on [0,1 ] are chosen as a starting point for characterizations of functions in Besov spaces B , (0,1) with 0<σ<∞ and (1+σ)-1<τ<∞. Such function spaces are known to be related to nonlinear approximation. Then so called restricted nonlinear approximation procedures with respect to Sobolev space norms are considered. Besides characterization results Jackson type estimates for various tree-type and tresholding algorithms are investigated. Finally known approximation results for geometry induced singularity functions of boundary integeral equations are combined with the characterization results for restricted nonlinear approximation to show Besov space regularity results.

  9. Analytical solution to stagnation-point flow and heat transfer over a stretching sheet based on homotopy analysis

    Institute of Scientific and Technical Information of China (English)

    Jing ZHU; Lian-cun ZHENG; Xin-xin ZHANG

    2009-01-01

    This paper is concerned with two-dimensional stagnation-point steady flow of an incompressible viscous fluid towards a stretching sheet whose velocity is proportional to the distance from the slit. The governing system of partial differential equations is first transformed into a system of dimensionless ordinary differential equations. Analytical solutions of the velocity distribution and dimensionless temperature profiles are obtained for different ratios of free stream velocity and stretching velocity, Prandtl number, Eckert number and dimensionality index in series forms using homotopy analysis method(HAM).It is shown that a boundary layer is formed when the free stream velocity exceeds the stretching velocity, and an inverted boundary layer is formed when the free stream velocity is less than the stretching velocity. Graphs are presented to show the effects of different parameters.

  10. Analytical solutions for ozone generation by point to plane corona discharge

    International Nuclear Information System (INIS)

    A recent mathematical model developed for ozone production is tackled analytically by asymptotic approximation. The results obtained are compared with existing numerical solutions. The comparison shows good agreement. (author). 3 refs, 1 fig

  11. A Quantum Dot with Spin-Orbit Interaction--Analytical Solution

    Science.gov (United States)

    Basu, B.; Roy, B.

    2009-01-01

    The practical applicability of a semiconductor quantum dot with spin-orbit interaction gives an impetus to study analytical solutions to one- and two-electron quantum dots with or without a magnetic field.

  12. The analyticity of solutions to a class of degenerate elliptic equations

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In the present paper,the analyticity of solutions to a class of degenerate elliptic equations is obtained.A kind of weighted norms are introduced and under such norms some degenerate elliptic operators are of weak coerciveness.

  13. Finding Approximate Analytic Solutions to Differential Equations by Seed Selection Genetic Programming

    Institute of Scientific and Technical Information of China (English)

    侯进军

    2007-01-01

    @@ 1 Seed Selection Genetic Programming In Genetic Programming, each tree in population shows an algebraic or surmounting expression, and each algebraic or surmounting expression shows an approximate analytic solution to differential equations.

  14. Reflecting Solutions of High Order Elliptic Differential Equations in Two Independent Variables Across Analytic Arcs. Ph.D. Thesis

    Science.gov (United States)

    Carleton, O.

    1972-01-01

    Consideration is given specifically to sixth order elliptic partial differential equations in two independent real variables x, y such that the coefficients of the highest order terms are real constants. It is assumed that the differential operator has distinct characteristics and that it can be factored as a product of second order operators. By analytically continuing into the complex domain and using the complex characteristic coordinates of the differential equation, it is shown that its solutions, u, may be reflected across analytic arcs on which u satisfies certain analytic boundary conditions. Moreover, a method is given whereby one can determine a region into which the solution is extensible. It is seen that this region of reflection is dependent on the original domain of difinition of the solution, the arc and the coefficients of the highest order terms of the equation and not on any sufficiently small quantities; i.e., the reflection is global in nature. The method employed may be applied to similar differential equations of order 2n.

  15. Integral solutions to transient nonlinear heat (mass) diffusion with a power-law diffusivity: a semi-infinite medium with fixed boundary conditions

    Science.gov (United States)

    Hristov, Jordan

    2016-03-01

    Closed form approximate solutions to nonlinear heat (mass) diffusion equation with power-law nonlinearity of the thermal (mass) diffusivity have been developed by the integral-balance method avoiding the commonly used linearization by the Kirchhoff transformation. The main improvement of the solution is based on the double-integration technique and a new approach to the space derivative. Solutions to Dirichlet and Neumann boundary condition problems have been developed and benchmarked against exact numerical and approximate analytical solutions available in the literature.

  16. An Analytical Solution for Acoustic Emission Source Location for Known P Wave Velocity System

    Directory of Open Access Journals (Sweden)

    Longjun Dong

    2014-01-01

    Full Text Available This paper presents a three-dimensional analytical solution for acoustic emission source location using time difference of arrival (TDOA measurements from N receivers, N⩾5. The nonlinear location equations for TDOA are simplified to linear equations, and the direct analytical solution is obtained by solving the linear equations. There are not calculations of square roots in solution equations. The method solved the problems of the existence and multiplicity of solutions induced by the calculations of square roots in existed close-form methods. Simulations are included to study the algorithms' performance and compare with the existing technique.

  17. Analytic Solutions of Three-Level Dressed-Atom Model

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-Ling; YIN Jian-Ping

    2004-01-01

    On the basis of the dressed-atom model, the general analytic expressions for the eigenenergies, eigenstates and their optical potentials of the A-configuration three-level atom system are derived and analysed. From the calculation of dipole matrix element of different dressed states, we obtain the spontaneous-emission rates in the dressed-atom picture. We find that our general expressions of optical potentials for the three-level dressed atom can be reduced to the same as ones in previous references under the approximation of a small saturation parameter. We also analyse the dependences of the optical potentials of a three-level 85Rb atom on the laser detuning and the dependences of spontaneous-emission rates on the radial position in the dark hollow beam, and discuss the probability (population) evolutions of dressed-atomic eigenstates in three levels in the hollow beam.

  18. Analytic Asymptotic Solution to Spherical Relativistic Shock Breakout

    CERN Document Server

    Yalinewich, Almog

    2016-01-01

    We investigate the relativistic breakout of a shock wave from the surface of a star. In this process, each fluid shell is endowed with some kinetic and thermal energy by the shock, and then continues to accelerate adiabatically by converting thermal energy into kinetic energy. This problem has been previously studied for a mildly relativistic breakout, where the acceleration ends close to the surface of the star. The current work focuses on the case where the acceleration ends at distances much greater than the radius of the star. We derive an analytic description for the hydrodynamic evolution of the ejecta in this regime, and validate it using a numerical simulation. We also provide predictions for the expected light curves and spectra from such an explosion. The relevance to astrophysical explosions is discussed, and it is shown that such events require more energy than is currently believed to result from astrophysical explosions.

  19. A New Analytical Solution to the Relativistic Polytropic Fluid Spheres

    CERN Document Server

    Nouh, Mohamed

    2014-01-01

    This paper introduces an accelerated power series solution for Tolman-Oppenheimer-Volkoff (TOV) equation, which represents the relativistic polytropic fluid spheres. We constructed a recurrence relation for the series coefficients in the power series expansion of the solution of TOV equation. For the range of the polytropic index 01.5, the series diverges except for some values of sigma. To improve the convergence radii of the series, we used a combination of two techniques Euler-Abel transformation and Pad\\'e approximation. The new transformed series converges everywhere for the range of the polytropic index 0<=n<=3. Comparison between the results obtained by the proposed accelerating scheme presented here and the numerical one, revealed good agreement with maximum relative error is of order 0.001.

  20. New Analytical Solutions of a Modified Black-Scholes Equation with the European Put Option

    OpenAIRE

    Juan Ospina

    2015-01-01

    Using Maple, we compute some analytical solutions of a modified Black-Scholes equation, recently proposed, in the case of the European put option. We show that the modified Black-Scholes equation with the European put option is exactly solvable in terms of associated Laguerre polynomials. We make some numerical experiments with the analytical solutions and we compare our results with the results derived from numerical experiments using the standard Black-Scholes equation.

  1. Analytical solutions for the slow neutron capture process of heavy element nucleosynthesis

    Institute of Scientific and Technical Information of China (English)

    Wu Kai-Su

    2009-01-01

    In this paper,the network equation for the slow neutron capture process (s-process) of heavy element nucleosynthesis is investigated. Dividing the s-process network reaction chains into two standard forms and using the technique of matrix decomposition,a group of analytical solutions for the network equation are obtained. With the analytical solutions,a calculation for heavy element abundance of the solar system is carried out and the results are in good agreement with the astrophysical measurements.

  2. Approximate Analytic Solutions of Transient Nonlinear Heat Conduction with Temperature-Dependent Thermal Diffusivity

    OpenAIRE

    Mustafa, M. T.; Arif, A. F. M.; Khalid Masood

    2014-01-01

    A new approach for generating approximate analytic solutions of transient nonlinear heat conduction problems is presented. It is based on an effective combination of Lie symmetry method, homotopy perturbation method, finite element method, and simulation based error reduction techniques. Implementation of the proposed approach is demonstrated by applying it to determine approximate analytic solutions of real life problems consisting of transient nonlinear heat conduction in semi-infinite bars...

  3. Exact travelling wave solutions of the symmetric regularized long wave (SRLW using analytical methods

    Directory of Open Access Journals (Sweden)

    Jalil Manafian Heris

    2014-02-01

    Full Text Available In this article, we establish exact travelling wave solutions of the symmetric regularized long wave (SRLW by using analytical methods. The analytical methods are: the tanh-coth method and the sech^2 method which used to construct solitary wave solutions of nonlinear evolution equations. With the help of symbolic computation, we show that aforementioned methods provide a straightforward and powerful mathematical tool for solving nonlinear partial differential equations.

  4. AN ANALYTICAL MODEL OF INTERSTELLAR GAS IN THE HELIOSPHERE TAILORED TO INTERSTELLAR BOUNDARY EXPLORER OBSERVATIONS

    International Nuclear Information System (INIS)

    The stationary distribution of interstellar neutral gas in the heliosphere subject to solar gravity, solar radiation pressure, photoionization, and charge exchange is investigated analytically assuming ionization rates and radiation pressure that are proportional to R–2, where R is the heliocentric radius. The collisionless hyperbolic trajectories of the individual atoms including ionization losses are combined with Liouville's Theorem to construct the heliospheric phase-space distribution function of an interstellar gas species in the solar reference frame under the assumption that the distribution is a drifting Maxwellian at large distances from the Sun. The distribution is transformed to the Earth (essentially Interstellar Boundary Explorer (IBEX)) frame as a function of solar longitude. The expression is then tailored to the latitudinal scan of IBEX as a function of longitude using the fact that IBEX detects each atom close to perihelion in its hyperbolic orbit. The distribution is further adapted to IBEX by integrating the differential intensity over the entrance aperture solid angle of the IBEX-Lo collimator, and over energy to predict the IBEX count rate of helium. The major features of the predicted count rate are described, including a peak in longitude, a peak in latitude at each longitude, and the widths of the major peak in both latitude and longitude. Analytical formulae for these features are derived for comparison with IBEX observations in order to determine the temperature and bulk velocity of the gas in interstellar space. Based in part on these formulae, the results for helium are presented in the companion paper by Möbius et al.

  5. An analytic solution to LO coupled DGLAP evolution equations: a new pQCD tool

    CERN Document Server

    Block, Martin M; Ha, Phuoc; McKay, Douglas W

    2010-01-01

    We have analytically solved the LO pQCD singlet DGLAP equations using Laplace transform techniques. Newly-developed highly accurate numerical inverse Laplace transform algorithms allow us to write fully decoupled solutions for the singlet structure function F_s(x,Q^2)and G(x,Q^2) as F_s(x,Q^2)={\\cal F}_s(F_{s0}(x), G_0(x)) and G(x,Q^2)={\\cal G}(F_{s0}(x), G_0(x)). Here {\\cal F}_s and \\cal G are known functions of the initial boundary conditions F_{s0}(x) = F_s(x,Q_0^2) and G_{0}(x) = G(x,Q_0^2), i.e., the chosen starting functions at the virtuality Q_0^2. For both G and F_s, we are able to either devolve or evolve each separately and rapidly, with very high numerical accuracy, a computational fractional precision of O(10^{-9}). Armed with this powerful new tool in the pQCD arsenal, we compare our numerical results from the above equations with the published MSTW2008 and CTEQ6L LO gluon and singlet F_s distributions, starting from their initial values at Q_0^2=1 GeV^2 and 1.69 GeV^2, respectively, using their ...

  6. Positive solutions of a boundary-value problem for second order ordinary differential equations

    Directory of Open Access Journals (Sweden)

    George L. Karakostas

    2000-06-01

    Full Text Available The existence of positive solutions of a two-point boundary value problem for a second order differential equation is investigated. By using indices of convergence of the nonlinearities at zero and at positive infinity, we providea priori upper and lower bounds for the slope of the solutions are also provided.

  7. Numerical solution to inverse elliptic problem with Neumann type overdetermination and mixed boundary conditions

    Directory of Open Access Journals (Sweden)

    Charyyar Ashyralyyev

    2015-07-01

    Full Text Available This article studies the numerical solution of inverse problems for the multidimensional elliptic equation with Dirichlet-Neumann boundary conditions and Neumann type overdetermination. We present first and second order accuracy difference schemes. The stability and almost coercive stability inequalities for the solution are obtained. Numerical examples with explanation on the implementation illustrate the theoretical results.

  8. Solitary-wave solutions in binary mixtures of Bose-Einstein condensates under periodic boundary conditions

    Science.gov (United States)

    Smyrnakis, J.; Magiropoulos, M.; Kavoulakis, G. M.; Jackson, A. D.

    2013-01-01

    We derive solitary-wave solutions within the mean-field approximation in quasi-one-dimensional binary mixtures of Bose-Einstein condensates under periodic boundary conditions, for the case of an effective repulsive interatomic interaction. The particular gray-bright solutions that give the global energy minima are determined. Their characteristics and the associated dispersion relation are derived.

  9. EXISTENCE OF SOLUTIONS TO 2m-ORDER PERIODIC BOUNDARY VALUE PROBLEM

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper, we are concerned with the existence of nontrivial solutions to a 2m-order nonlinear periodic boundary value problem. By the infinite dimensional Morse theory, under some conditions on nonlinear term, we obtain that there exist at least two nontrivial solutions.

  10. Solution of a singularly perturbed nonstationary fourth-order boundary-value problem

    Energy Technology Data Exchange (ETDEWEB)

    Makarov, V.L.; Guminskii, V.V. [Kiev State Univ. (Ukraine)

    1994-06-05

    A difference scheme is constructed by the method of lines for a nonstationary boundary-value problem for a fourth-order equation in the space coordinate. The uniform convergence with respect to a small parameter, of the solution of the linearization scheme to a solution of the original problem is proven. 8 refs.

  11. Positive solutions of second-order singular boundary value problem with a Laplace-like operator

    Directory of Open Access Journals (Sweden)

    Ge Weigao

    2005-01-01

    Full Text Available By use of the concavity of solution for an associate boundary value problem, existence criteria of positive solutions are given for the Dirichlet BVP , , , where is odd and continuous with , , and may change sign and be singular along a curve in .

  12. Analytical solutions of the problem of violent explosions in a plasma of varying density

    International Nuclear Information System (INIS)

    Analytical solutions of the non-linear problem of violent explosions in a plasma of varying density under power law have been obtained. A critical law for a medium of decreasing density from the source of explosion is determined for which the problem admits a very simple solution but beyond this critical line analytical solutions admit another discontinuity automatically occuring inside a blast wave region. It is assumed that a disturbance caused by violent explosion due to sudden release of immense amount of energy is expanding very rapidly and is headed by a strong MHD shock wave. It is found that the discontinuity appearing inside a blast wave region causes a violation of continuum theory in the physical plane and consequently a cavity is formed. Analytical solutions predict that just before a discontinuity appears, the gas pressure falls to zero and the solution breaks down and can not be extended further. (Auth.)

  13. On the physical solutions to the heat equation subjected to nonlinear boundary conditions

    International Nuclear Information System (INIS)

    This work consists of a discussion on the physical solutions to the steady-state heat transfer equation, when it is subjected to nonlinear boundary conditions. It will be presented a functional, whose minimum occurs for the (unique) physical solution to the condidered heat transfer problem, suitable for a large class of typical (nonlinear) boundary conditions (representing the radiative/convective loss from the body to the environment). It will be demonstrated that these problems admit-always one, and only one, physical solution (which represents the absolute temperature). (author)

  14. Analysing an Analytical Solution Model for Simultaneous Mobility

    Directory of Open Access Journals (Sweden)

    Md. Ibrahim Chowdhury

    2013-12-01

    Full Text Available Current mobility models for simultaneous mobility h ave their convolution in designing simultaneous movement where mobile nodes (MNs travel randomly f rom the two adjacent cells at the same time and also have their complexity in the measurement of th e occurrences of simultaneous handover. Simultaneou s mobility problem incurs when two of the MNs start h andover approximately at the same time. As Simultaneous mobility is different for the other mo bility pattern, generally occurs less number of tim es in real time; we analyze that a simplified simultaneou s mobility model can be considered by taking only symmetric positions of MNs with random steps. In ad dition to that, we simulated the model using mSCTP and compare the simulation results in different sce narios with customized cell ranges. The analytical results shows that with the bigger the cell sizes, simultaneous handover with random steps occurrences become lees and for the sequential mobility (where initial positions of MNs is predetermined with ran dom steps, simultaneous handover is more frequent.

  15. Analytic solutions for degenerate Raman-coupled model

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhi-Ming; Yu Ya-Fei

    2008-01-01

    The Raman-coupled interaction between an atom and a single mode of a cavity field is studied. For the cases in which a light field is initially in a coherent state and in a thermal state separately, we have derived the analytic expressions for the time evolutions of atomic population difference W, modulus B of the Bloch vector, and entropy E. We find that the time evolutions of these quantities are periodic with a period of e. The maxima of W and B appear at the scaled interaction time points (τ) = κπ(κ =0, 1, 2,...). At these time points, E = 0, which shows that the atom and the field are not entangled. Between these time points, E ≠ 0, which means that the atom and the field are entangled. When the field is initially in a coherent state, near the maxima, the envelope of W is a Gaussian function with a variance of 1/(4(-n)) ((-n) is the mean number of photons). Under the envelope, W oscillates at a frequency of (-n)/e.When the field is initially in a thermal state, near the maxima, W is a Lorentz function with a width of 1/(-n).

  16. Approximate analytical solutions for excitation and propagation in cardiac tissue

    Science.gov (United States)

    Greene, D'Artagnan; Shiferaw, Yohannes

    2015-04-01

    It is well known that a variety of cardiac arrhythmias are initiated by a focal excitation in heart tissue. At the single cell level these currents are typically induced by intracellular processes such as spontaneous calcium release (SCR). However, it is not understood how the size and morphology of these focal excitations are related to the electrophysiological properties of cardiac cells. In this paper a detailed physiologically based ionic model is analyzed by projecting the excitation dynamics to a reduced one-dimensional parameter space. Based on this analysis we show that the inward current required for an excitation to occur is largely dictated by the voltage dependence of the inward rectifier potassium current (IK 1) , and is insensitive to the detailed properties of the sodium current. We derive an analytical expression relating the size of a stimulus and the critical current required to induce a propagating action potential (AP), and argue that this relationship determines the necessary number of cells that must undergo SCR in order to induce ectopic activity in cardiac tissue. Finally, we show that, once a focal excitation begins to propagate, its propagation characteristics, such as the conduction velocity and the critical radius for propagation, are largely determined by the sodium and gap junction currents with a substantially lesser effect due to repolarizing potassium currents. These results reveal the relationship between ion channel properties and important tissue scale processes such as excitation and propagation.

  17. An Analytical Solution for Cylindrical Concrete Tank on Deformable Soil

    Directory of Open Access Journals (Sweden)

    Shirish Vichare

    2010-07-01

    Full Text Available Cylindrical concrete tanks are commonly used in wastewater treatment plants. These are usually clarifier tanks. Design codes of practice provide methods to calculate design forces in the wall and raft of such tanks. These methods neglect self-weight of tank material and assume extreme, namely ‘fixed’ and ‘hinged’ conditions for the wall bottom. However, when founded on deformable soil, the actual condition at the wall bottom is neither fixed nor hinged. Further, the self-weight of the tank wall does affect the design forces. Thus, it is required to offer better insight of the combined effect of deformable soil and bottom raft stiffness on the design forces induced in such cylindrical concrete tanks. A systematic analytical method based on fundamental equations of shells is presented in this paper. Important observations on variation of design forces across the wall and the raft with different soil conditions are given. Set of commonly used tanks, are analysed using equations developed in the paper and are appended at the end.

  18. Analytical solutions for sensitivity contribution in nuclear imaging

    Science.gov (United States)

    DiPirro, Joseph Christopher

    The use of slit-slat collimation in diagnostic medical nuclear imaging is analyzed for the purpose of finding background sensitivity. A general derivation of sensitivity contribution is expressed for various camera positions outside particular radioactive objects. These objects can represent possible human or animal organs for different clinical imaging tasks. Rectangular, circular, elliptical, and parabolic cross-sections are analyzed for a given set of variables to represent the total background contribution within any particular shape for any given detector location, whether it is a point, line, or area sensitivity contribution. The sensitivity of a point source is calculated for any location inside the slit-slat's field-of-view as a function of the following constraints: (i) object shape, (ii) slit distance, (iii) depth within the object, (iv) acceptance angle, and if necessary (v) attenuation coefficient of the medium, and (vi) lateral displacement of the detector. The analysis is split into parts for all shapes to find the line or area contribution within an object. The sum of the point sources can be performed digitally to find a solution in terms of the provided situation; in some cases, an exact solution was found. The line sensitivity contributions can be applied to slit-slat cameras to reduce noise and fluctuation in imaging system design and analysis.

  19. Analytical solutions for Dirac and Klein-Gordon equations using Backlund transformations

    Energy Technology Data Exchange (ETDEWEB)

    Zabadal, Jorge R.; Borges, Volnei, E-mail: jorge.zabadal@ufrgs.br, E-mail: borges@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Engenharia Mecanica; Ribeiro, Vinicius G., E-mail: vinicius_ribeiro@uniritter.edu.br [Centro Universitario Ritter dos Reis (UNIRITTER), Porto Alegre, RS (Brazil); Santos, Marcio, E-mail: marciophd@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Centro de Estudos Interdisciplinares

    2015-07-01

    This work presents a new analytical method for solving Klein-Gordon type equations via Backlund transformations. The method consists in mapping the Klein-Gordon model into a first order system of partial differential equations, which contains a generalized velocity field instead of the Dirac matrices. This system is a tensor model for quantum field theory whose space solution is wider than the Dirac model in the original form. Thus, after finding analytical expressions for the wave functions, the Maxwell field can be readily obtained from the Dirac equations, furnishing a self-consistent field solution for the Maxwell-Dirac system. Analytical and numerical results are reported. (author)

  20. Analytic solutions and Singularity formation for the Peakon b--Family equations

    OpenAIRE

    Coclite, Giuseppe Maria; Gargano, Francesco; Sciacca, Vincenzo

    2012-01-01

    Using the Abstract Cauchy-Kowalewski Theorem we prove that the $b$-family equation admits, locally in time, a unique analytic solution. Moreover, if the initial data is real analytic and it belongs to $H^s$ with $s > 3/2$, and the momentum density $u_0 - u_{0,{xx}}$ does not change sign, we prove that the solution stays analytic globally in time, for $b\\geq 1$. Using pseudospectral numerical methods, we study, also, the singularity formation for the $b$-family equations with the singularity t...

  1. Analytical solution for laser evaporative heating process: time exponentially decaying pulse case

    International Nuclear Information System (INIS)

    The modelling of the laser heating process gives insight into the laser workpiece interaction and minimizes the experimental cost. In the present study, analytical solution for the laser pulse heating process is considered and the closed form solution for the temperature rise due to time exponentially varying pulse is obtained. In the analysis, evaporation of the surface is taken into account. A Laplace transformation method was used when formulating the closed form solution for the temperature profiles. The effect of pulse parameters on the temperature profiles is examined in detail. It is found that the closed form solution derived from the present study reduces to the previously obtained analytical solution when the surface recession velocity is set to zero in the closed form solution. Moreover, the predictions of numerical simulation and closed form solution are found to be in good agreement. (author)

  2. Comparing (semi-) analytic solutions used to model the impact of deep carbon injection on the displacement and pressurization of the resident brine

    Science.gov (United States)

    Bandilla, K.; Kraemer, S. R.

    2009-12-01

    Injection of carbon dioxide into deep saline formations is seen as one possible technology for mitigating carbon emissions from utilities. The safety of the sequestered carbon dioxide is the focus of many studies with leakage through faults or abandoned wells as some of the main failure mechanisms. The focus of this study is on the displacement of resident brine and the resulting changes in pressure due to the injection of large volumes of super-critical phase carbon dioxide into the subsurface. The movement of brine becomes important if it travels vertically and reaches an existing or potential underground source of drinking water where an increase in salt content may threaten the viability of the drinking water source. Vertical displacement of brine may occur slowly through confining layers, or more rapidly through faults and abandoned wells. This presentation compares several (semi-) analytic solutions to determine their applicability to the problem of brine pressurization and displacement. The goal is to find ranges of formation parameters (e.g., formation seal conductivity, distance to lateral boundary, … ) for which simplifying assumption are justifiable Each simplification in the conceptual model (e.g., neglecting the lateral boundary turns a bounded domain into an infinite one) leads to a simpler (semi-) analytic solution. The process involves a solution hierarchy from the most complex solution down to the basic Theis solution. A software tool-kit implementing several (semi-) analytic solutions was developed for this study to facilitate the comparison of the solutions.

  3. Lempert Theorem for strictly linearly convex domains with real analytic boundaries

    CERN Document Server

    Kosinski, L

    2012-01-01

    The aim of this paper is to present a detailed and slightly modified version of the proof of the Lempert Theorem in the case of non-planar strictly linearly convex domains with real analytic boundaries. The original Lempert's proof is presented only in proceedings of a conference with a very limited access and at some places it was quite sketchy. We were encouraged by some colleagues to prepare an extended version of the proof in which all doubts could be removed and some of details of the proofs could be simplified. We hope to have done it below. Certainly the idea of the proof belongs entirely to Lempert. Additional motivation for presenting the proof is the fact shown recently, that the so-called symmetrized bidisc may be exhausted by strictly linearly convex domains. On the other hand it cannot be exhausted by domains biholomorphic to convex ones. Therefore, the equality of the Lempert function and the Carath\\'eodory distance for strictly linearly convex domains does not follow directly from the convex ca...

  4. Boundary value problems of finite elasticity local theorems on existence, uniqueness, and analytic dependence on data

    CERN Document Server

    Valent, Tullio

    1988-01-01

    In this book I present, in a systematic form, some local theorems on existence, uniqueness, and analytic dependence on the load, which I have recently obtained for some types of boundary value problems of finite elasticity. Actually, these results concern an n-dimensional (n ~ 1) formal generalization of three-dimensional elasticity. Such a generalization, be­ sides being quite spontaneous, allows us to consider a great many inter­ esting mathematical situations, and sometimes allows us to clarify certain aspects of the three-dimensional case. Part of the matter presented is unpublished; other arguments have been only partially published and in lesser generality. Note that I concentrate on simultaneous local existence and uniqueness; thus, I do not deal with the more general theory of exis­ tence. Moreover, I restrict my discussion to compressible elastic bodies and I do not treat unilateral problems. The clever use of the inverse function theorem in finite elasticity made by STOPPELLI [1954, 1957a, 1957b]...

  5. Super stellar clusters with a bimodal hydrodynamic solution: an Approximate Analytic Approach

    CERN Document Server

    Wünsch, R; Palous, J; Tenorio-Tagle, G

    2007-01-01

    We look for a simple analytic model to distinguish between stellar clusters undergoing a bimodal hydrodynamic solution from those able to drive only a stationary wind. Clusters in the bimodal regime undergo strong radiative cooling within their densest inner regions, which results in the accumulation of the matter injected by supernovae and stellar winds and eventually in the formation of further stellar generations, while their outer regions sustain a stationary wind. The analytic formulae are derived from the basic hydrodynamic equations. Our main assumption, that the density at the star cluster surface scales almost linearly with that at the stagnation radius, is based on results from semi-analytic and full numerical calculations. The analytic formulation allows for the determination of the threshold mechanical luminosity that separates clusters evolving in either of the two solutions. It is possible to fix the stagnation radius by simple analytic expressions and thus to determine the fractions of the depo...

  6. Analytical solutions of the planar cyclic voltammetry process for two soluble species with equal diffusivities and fast electron transfer using the method of eigenfunction expansions

    International Nuclear Information System (INIS)

    Cyclic voltammetry is a powerful tool that is used for characterizing electrochemical processes. Models of cyclic voltammetry take into account the mass transport of species and the kinetics at the electrode surface. Analytical solutions of these models are not well-known due to the complexity of the boundary conditions. In this study we present closed form analytical solutions of the planar voltammetry model for two soluble species with fast electron transfer and equal diffusivities using the eigenfunction expansion method. Our solution methodology does not incorporate Laplace transforms and yields good agreement with the numerical solution. This solution method can be extended to cases that are more general and may be useful for benchmarking purposes

  7. Analytical solutions of the planar cyclic voltammetry process for two soluble species with equal diffusivities and fast electron transfer using the method of eigenfunction expansions

    Energy Technology Data Exchange (ETDEWEB)

    Samin, Adib; Lahti, Erik; Zhang, Jinsuo, E-mail: zhang.3558@osu.edu [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19" t" h Avenue, Columbus, Ohio 43210 (United States)

    2015-08-15

    Cyclic voltammetry is a powerful tool that is used for characterizing electrochemical processes. Models of cyclic voltammetry take into account the mass transport of species and the kinetics at the electrode surface. Analytical solutions of these models are not well-known due to the complexity of the boundary conditions. In this study we present closed form analytical solutions of the planar voltammetry model for two soluble species with fast electron transfer and equal diffusivities using the eigenfunction expansion method. Our solution methodology does not incorporate Laplace transforms and yields good agreement with the numerical solution. This solution method can be extended to cases that are more general and may be useful for benchmarking purposes.

  8. Analytical solutions of the planar cyclic voltammetry process for two soluble species with equal diffusivities and fast electron transfer using the method of eigenfunction expansions

    Directory of Open Access Journals (Sweden)

    Adib Samin

    2015-08-01

    Full Text Available Cyclic voltammetry is a powerful tool that is used for characterizing electrochemical processes. Models of cyclic voltammetry take into account the mass transport of species and the kinetics at the electrode surface. Analytical solutions of these models are not well-known due to the complexity of the boundary conditions. In this study we present closed form analytical solutions of the planar voltammetry model for two soluble species with fast electron transfer and equal diffusivities using the eigenfunction expansion method. Our solution methodology does not incorporate Laplace transforms and yields good agreement with the numerical solution. This solution method can be extended to cases that are more general and may be useful for benchmarking purposes.

  9. Analytical solutions of the planar cyclic voltammetry process for two soluble species with equal diffusivities and fast electron transfer using the method of eigenfunction expansions

    Science.gov (United States)

    Samin, Adib; Lahti, Erik; Zhang, Jinsuo

    2015-08-01

    Cyclic voltammetry is a powerful tool that is used for characterizing electrochemical processes. Models of cyclic voltammetry take into account the mass transport of species and the kinetics at the electrode surface. Analytical solutions of these models are not well-known due to the complexity of the boundary conditions. In this study we present closed form analytical solutions of the planar voltammetry model for two soluble species with fast electron transfer and equal diffusivities using the eigenfunction expansion method. Our solution methodology does not incorporate Laplace transforms and yields good agreement with the numerical solution. This solution method can be extended to cases that are more general and may be useful for benchmarking purposes.

  10. Periodic Solutions of the Vlasov-Poisson System with Boundary Conditions

    OpenAIRE

    Bostan, Mihai; Poupaud, Frédéric

    1998-01-01

    We study the Vlasov-Poisson system with time periodic boundary conditions. For small data we prove existence of weak periodic solutions in any space dimension. In the one dimensional case the result is stronger: we obtain existence of mild solution and uniqueness of this solution when the data are smooth. It is necessary to impose a non vanishing condition for the incoming velocities in order to control the life-time of particles in the domain.

  11. Asymptotic behavior of solutions to wave equations with a memory condition at the boundary

    Directory of Open Access Journals (Sweden)

    Mauro de Lima Santos

    2001-11-01

    Full Text Available In this paper, we study the stability of solutions for wave equations whose boundary condition includes a integral that represents the memory effect. We show that the dissipation is strong enough to produce exponential decay of the solution, provided the relaxation function also decays exponentially. When the relaxation function decays polynomially, we show that the solution decays polynomially and with the same rate.

  12. A new method for deriving analytical solutions of partial differential equations-Algebraically explicit analytical solutions of two-buoyancy natural convection in porous media

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Analytical solutions of governing equations of various phenomena have their irre-placeable theoretical meanings. In addition, they can also be the benchmark solu-tions to verify the outcomes and codes of numerical solutions, and even to develop various numerical methods such as their differencing schemes and grid generation skills as well. A hybrid method of separating variables for simultaneous partial differential equation sets is presented. It is proposed that different methods of separating variables for different independent variables in the simultaneous equa-tion set may be used to improve the solution derivation procedure, for example, using the ordinary separating method for some variables and using extraordinary methods of separating variables, such as the separating variables with addition promoted by the first author, for some other variables. In order to prove the ability of the above-mentioned hybrid method, a lot of analytical exact solutions of two-buoyancy convection in porous media are successfully derived with such a method. The physical features of these solutions are given.

  13. A new method for deriving analytical solutions of partial differential equations--Algebraically explicit analytical solutions of two-buoyancy natural convection in porous media

    Institute of Scientific and Technical Information of China (English)

    CAI RuiXian; LIU QiBin

    2008-01-01

    Analytical solutions of governing equations of various phenomena have their irre-placeable theoretical meanings. In addition, they can also be the benchmark solu-tions to verify the outcomes and codes of numerical solutions, and even to develop various numerical methods such as their differencing schemes and grid generation skills as well. A hybrid method of separating variables for simultaneous partial differential equation sets is presented. It is proposed that different methods of separating variables for different independent variables in the simultaneous equa-tion set may be used to improve the solution derivation procedure, for example, using the ordinary separating method for some variables and using extraordinary methods of separating variables, such as the separating variables with addition promoted by the first author, for some other variables. In order to prove the ability of the above-mentioned hybrid method, a lot of analytical exact solutions of two-buoyancy convection in porous media are successfully derived with such a method. The physical features of these solutions are given.

  14. An analytic solution of the non-stationary Navier-Stokes equation in three dimensions

    OpenAIRE

    Thambynayagam, R. K. Michael

    2014-01-01

    In this paper we describe a method to derive classical solutions of the Navier-Stokes equations for non-stationary initial value problems in domain R^n (n = 2, 3 or higher). A new closed-form analytic solution of the incompressible Navier-Stokes equations on the decay of vortices in a viscous fluid in R3 is presented.

  15. Analytical solution of a class of coupled second order differential-difference equations

    Directory of Open Access Journals (Sweden)

    J. A. Martin Alustiza

    1993-06-01

    Full Text Available In this paper coupled systems of second order differential-difference equations are considered. By means of the concept of co-solution of certain algebraic equations associated to the problem, an analytical solution of initial value problems for coupled systems of second order differential-difference equations is constructed.

  16. Analytic solutions and universal properties of sugar loading models in Münch phloem flow

    DEFF Research Database (Denmark)

    Jensen, Kåre Hartvig; Berg-Sørensen, Kirstine; Friis, Søren Michael Mørk;

    2012-01-01

    relied on numerical solutions, which makes it difficult to draw general conclusions. Here, we present analytic solutions to the Münch–Horwitz flow equations when the loading and unloading rates are assumed to be linear functions of the concentration, thus allowing them to depend on the local osmotic...

  17. Analytical Solution of Nonlinear Problems in Classical Dynamics by Means of Lagrange-Ham

    DEFF Research Database (Denmark)

    Kimiaeifar, Amin; Mahdavi, S. H; Rabbani, A.;

    2011-01-01

    equation is solved analytically by Homotopy Analysis Methods. Present solution gives an expression which can be used in wide range of time for all domain of response. Comparisons of the obtained solutions with numerical results show that this method is effective and convenient for solving this problem....

  18. Analytical solutions for whirling groundwater flow in two-dimensional heterogeneous anisotropic aquifers

    NARCIS (Netherlands)

    Hemker, K.; Bakker, M.

    2006-01-01

    Analytical solutions are derived for steady state groundwater flow in a heterogeneous, anisotropic, semiconfined aquifer. The aquifer consists of a number of horizontal layers, while each layer consists of a number of homogeneous cells with different hydraulic conductivity tensors. An exact solution

  19. Method for constructing approximate analytic solutions of differential equations with a polynomial right-hand side

    Science.gov (United States)

    Afanas'ev, A. P.; Dzyuba, S. M.

    2015-10-01

    A method for constructing approximate analytic solutions of systems of ordinary differential equations with a polynomial right-hand side is proposed. The implementation of the method is based on the Picard method of successive approximations and a procedure of continuation of local solutions. As an application, the problem of constructing the minimal sets of the Lorenz system is considered.

  20. Analytic solutions to dynamic equations of plasma armature railguns

    Energy Technology Data Exchange (ETDEWEB)

    Shahinpoor, M.; Hawke, R.S.

    1988-01-01

    General governing nonlinear differential equations pertaining to the dynamic behavior of a plasma armature electromagnetic railgun are first derived. Three different cases are then considered and the corresponding governing equations are then solved exactly by means of a set of nonlinear transformations. These cases correspond to (1) no-ablation, (2) continuous-ablation, and (3) partial-ablation for which an ablation threshold velocity v/sub t/ plays a fundamental role. Corresponding to each case, a nonlinear transformation is employed to reduce the nonlinear differential equations to their equivalent linear ones and subsequently allow solution of the pertinent linear differential equations, which are second order, by means of the transition matrix technique. It is concluded that in order to achieve very high projectile velocities the projectile should be injected into the railgun at velocities higher than the ablation threshold velocity. Thus, the ablation may be completely alleviated and the ensuing turbulent drag may be significantly diminished. It is shown that under these conditions one may typically accelerate projectiles up to 30 km/s or more while without hypervelocity injection, for the same railgun and typical operating conditions, one might severely limit the maximum projectile velocity.

  1. Analytic solutions to dynamic equations of plasma armature railguns

    Energy Technology Data Exchange (ETDEWEB)

    Shahinpoor, M. (New Mexico Univ., Albuquerque, NM (USA). Dept. of Mechanical Engineering); Hawke, R.S. (Lawrence Livermore National Lab., CA (USA))

    1989-01-01

    General governing nonlinear differential equations pertaining to the dynamic behavior of a plasma armature electromagnetic railgun are first derived. Three different cases are then considered and the corresponding governing equations are then solved exactly by means of a set of nonlinear transformations. These cases correspond to (1) no-ablation, (2) continuous-ablation, and (3) partial-ablation for which an ablation threshold velocity {nu}/sub tau/ plays a fundamental role. Corresponding to each case, a nonlinear transformation is employed to reduce the nonlinear differential equations to their equivalent linear ones and subsequently allow solution of the pertinent linear differential equations, which are second order, by means of the transition matrix technique. It is concluded that in order to achieve very high projectile velocities the projectile should be injected into the railgun at velocities higher than the ablation threshold velocity. Thus, the ablation may be completely alleviated and the ensuing turbulent drag may be significantly diminished. It is shown that under these conditions one may typically accelerate projectiles up to 30 km/s or more while without hypervelocity injection, for the same railgun and typical operating conditions, one might severely limit the maximum projectile velocity.

  2. Analytical solutions of cracks emanating from an elliptical hole under shear

    Institute of Scientific and Technical Information of China (English)

    Liu Shuhong; Duan Shijie

    2014-01-01

    Based on the complex variable method, the analytical solutions of stress functions and stress intensity factors (SIFs) are provided for the plane problem of two collinear edge cracks emanating from an elliptical hole in an infinite plate under shear. The stress distribution along the horizontal axis is given in graphical forms, which conforms to Saint-Venant’s principle. The influences of crack length and ellipse shape on the stress intensity factors are evaluated. Comparing the analytical solutions with finite element method (FEM) results shows good coincidence. These numerical examples show that the present solutions are accurate.

  3. An approximate analytical solution for interlaminar stresses in angle-ply laminates

    Science.gov (United States)

    Rose, Cheryl A.; Herakovich, Carl T.

    1991-01-01

    An improved approximate analytical solution for interlaminar stresses in finite width, symmetric, angle-ply laminated coupons subjected to axial loading is presented. The solution is based upon statically admissible stress fields which take into consideration local property mismatch effects and global equilibrium requirements. Unknown constants in the admissible stress states are determined through minimization of the complementary energy. Typical results are presented for through-the-thickness and interlaminar stress distributions for angle-ply laminates. It is shown that the results represent an improved approximate analytical solution for interlaminar stresses.

  4. Nonlinear analytical solution for one-dimensional consolidation of soft soil under cyclic loading

    Institute of Scientific and Technical Information of China (English)

    XIE Kang-he; QI Tian; DONG Ya-qin

    2006-01-01

    This paper presents an analytical solution for one-dimensional consolidation of soft soil under some common types of cyclic loading such as trapezoidal cyclic loading, based on the assumptions proposed by Davis and Raymond (1965) that the decrease in permeability is proportional to the decrease in compressibility during the consolidation process of the soil and that the distribution of initial effective stress is constant with depth. It is verified by the existing analytical solutions in special cases. Using the solution obtained, some diagrams are prepared and the relevant consolidation behavior is investigated.

  5. Structural vibration a uniform accurate solution for laminated beams, plates and shells with general boundary conditions

    CERN Document Server

    Jin, Guoyong; Su, Zhu

    2015-01-01

    This book develops a uniform accurate method which is capable of dealing with vibrations of laminated beams, plates and shells with arbitrary boundary conditions including classical boundaries, elastic supports and their combinations. It also provides numerous solutions for various configurations including various boundary conditions, laminated schemes, geometry and material parameters, which fill certain gaps in this area of reach and may serve as benchmark solutions for the readers. For each case, corresponding fundamental equations in the framework of classical and shear deformation theory are developed. Following the fundamental equations, numerous free vibration results are presented for various configurations including different boundary conditions, laminated sequences and geometry and material properties. The proposed method and corresponding formulations can be readily extended to static analysis.

  6. GLOBAL C1 SOLUTION TO THE INITIAL-BOUNDARY VALUE PROBLEM FOR DIAGONAL HYPERBOLIC SYSTEMS WITH LINEARLY DEGENERATE CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    Li Ta-tsien(李大潜); Peng Yue-Jun

    2003-01-01

    Abstract We prove that the C0 boundedness of solution impliesthe global existence and uniqueness of C1 solution to the initial-boundary value problem for linearly degenerate quasilinear hyperbolic systems of diagonal form with nonlinear boundary conditions. Thus, if the C1 solution to the initial-boundary value problem blows up in a finite time, then the solution itself must tend to the infinity at the starting point of singularity.

  7. On Analytical Solutions of the Fractional Differential Equation with Uncertainty: Application to the Basset Problem

    Directory of Open Access Journals (Sweden)

    Soheil Salahshour

    2015-02-01

    Full Text Available In this paper, we apply the concept of Caputo’s H-differentiability, constructed based on the generalized Hukuhara difference, to solve the fuzzy fractional differential equation (FFDE with uncertainty. This is in contrast to conventional solutions that either require a quantity of fractional derivatives of unknown solution at the initial point (Riemann–Liouville or a solution with increasing length of their support (Hukuhara difference. Then, in order to solve the FFDE analytically, we introduce the fuzzy Laplace transform of the Caputo H-derivative. To the best of our knowledge, there is limited research devoted to the analytical methods to solve the FFDE under the fuzzy Caputo fractional differentiability. An analytical solution is presented to confirm the capability of the proposed method.

  8. Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in a conductor

    Science.gov (United States)

    Grants, Ilmārs; Bojarevičs, Andris; Gerbeth, Gunter

    2016-06-01

    Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-similar function for which we obtain an explicit expression. The validity range of various approximate analytical solutions is evaluated by comparison to the exact solution.

  9. Algebraically explicit analytical solutions for the unsteady non-Newtonian swirling flow in an annular pipe

    Institute of Scientific and Technical Information of China (English)

    CAI; Ruixian; GOU; Chenhua

    2006-01-01

    This paper presents two algebraically explicit analytical solutions for the incompressible unsteady rotational flow of Oldroyd-B type in an annular pipe. The first solution is derived with the common method of separation of variables. The second one is deduced with the method of separation of variables with addition developed in recent years. The first analytical solution is of clear physical meaning and both of them are fairly simple and valuable for the newly developing computational fluid dynamics. They can be used as the benchmark solutions to verify the applicability of the existing numerical computational methods and to inspire new differencing schemes, grid generation ways, etc. Moreover, a steady solution for the generalized second grade rheologic fluid flow is also presented. The correctness of these solutions can be easily proven by substituting them into the original governing equation.

  10. Finite volume approximation of the three-dimensional flow equation in axisymmetric, heterogeneous porous media based on local analytical solution

    KAUST Repository

    Salama, Amgad

    2013-09-01

    In this work the problem of flow in three-dimensional, axisymmetric, heterogeneous porous medium domain is investigated numerically. For this system, it is natural to use cylindrical coordinate system, which is useful in describing phenomena that have some rotational symmetry about the longitudinal axis. This can happen in porous media, for example, in the vicinity of production/injection wells. The basic feature of this system is the fact that the flux component (volume flow rate per unit area) in the radial direction is changing because of the continuous change of the area. In this case, variables change rapidly closer to the axis of symmetry and this requires the mesh to be denser. In this work, we generalize a methodology that allows coarser mesh to be used and yet yields accurate results. This method is based on constructing local analytical solution in each cell in the radial direction and moves the derivatives in the other directions to the source term. A new expression for the harmonic mean of the hydraulic conductivity in the radial direction is developed. Apparently, this approach conforms to the analytical solution for uni-directional flows in radial direction in homogeneous porous media. For the case when the porous medium is heterogeneous or the boundary conditions is more complex, comparing with the mesh-independent solution, this approach requires only coarser mesh to arrive at this solution while the traditional methods require more denser mesh. Comparisons for different hydraulic conductivity scenarios and boundary conditions have also been introduced. © 2013 Elsevier B.V.

  11. LOCAL CLASSICAL SOLUTION OF FREE BOUNDARY PROBLEM FOR A COUPLED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaohua; Yi Fahuai; Yang Zhou

    2005-01-01

    This paper considers a two-phase free boundary problem for coupled system including one parabolic equation and two elliptic equations. The problem comes from the discussion of a growth model of self-maintaining protocell in multidimensional case. The local classical solution of the problem with free boundary Γ:y = g(x, t) between two domains is being seeked. The local existence and uniqueness of the problem will be proved in multidimensional case.

  12. Conforming Discretizations of Boundary Element Solutions of the Electroencephalography Forward Problem

    CERN Document Server

    Rahmouni, Lyes; Cools, Kristof; Andriulli, Francesco P

    2016-01-01

    In this paper we present a new discretization strategy for the boundary element formulation of the Electroencephalography (EEG) forward problem. Boundary integral formulations, classically solved with the Boundary Element Method (BEM), are widely used in high resolution EEG imaging because of their recognized advantages in several real case scenarios. Unfortunately however, it is widely reported that the accuracy of standard BEM schemes is limited, especially when the current source density is dipolar and its location approaches one of the brain boundary surfaces. This is a particularly limiting problem given that during an high-resolution EEG imaging procedure, several EEG forward problem solutions are required for which the source currents are near or on top of a boundary surface. This work will first present an analysis of standardly discretized EEG forward problems, reporting on a theoretical issue of some of the formulations that have been used so far in the community. We report on the fact that several ...

  13. Properties of the exact analytic solution of the growth factor and its applications

    International Nuclear Information System (INIS)

    There have been the approximate analytic solution [V. Silveira and I. Waga, Phys. Rev. D 50, 4890 (1994).] and several approximate analytic forms [W. J. Percival, Astron. Astrophys. 443, 819 (2005).][S. M. Carroll, W. H. Press, and E. L. Turner, Annu. Rev. Astron. Astrophys. 30, 499 (1992).][S. Basilakos, Astrophys. J. 590, 636 (2003).] of the growth factor Dg for the general dark energy models with the constant values of its equation of state ωde after Heath found the exact integral form of the solution of Dg for the Universe including the cosmological constant or the curvature term. Recently, we obtained the exact analytic solutions of the growth factor for both ωde=-1 or -(1/3)[S. Lee and K.-W. Ng, arXiv:0905.1522.] and the general dark energy models with the constant equation of state ωde[S. Lee and K.-W. Ng, Phys. Lett. B 688, 1 (2010).] independently. We compare the exact analytic solution of Dg with the other well known approximate solutions. We also prove that the analytic solutions for ωde=-1 or -(1/3) in [S. Lee and K.-W. Ng, arXiv:0905.1522.] are the specific solutions of the exact solutions of the growth factor for general ωde models in [S. Lee and K.-W. Ng, Phys. Lett. B 688, 1 (2010).] even though they look quite different. Comparison with the numerical solution obtained from the public code is done. We also investigate the possible extensions of the exact solution of Dg to the time-varying ωde for the comparison with observations.

  14. Semi analytical solution of point kinetic equation with source from cold start up to delayed critical

    International Nuclear Information System (INIS)

    Point kinetics equations (P. K. E) are system of differential equations, which is solved simultaneously to get the neutron density as a function of time for a given reactivity input. P. K. E are stiff differential equations, computational solution through the conventional explicit method will give a stable consistent result only for smaller time steps. Analytical solutions are available either with step or ramp reactivity insertion without considering the source power contribution. When a reactor operates at low power, the neutron source gives a considerable contribution to the net reactor power. Similarly, when the reactor is brought to delayed critical with the presence of external source, the sub critical reactor kinetics studies with source power are important to understand the power behavior as a function of reactivity insertion rate with respect to the initial reactivity. In the present work, P.K.E with one group delayed neutron are solved analytically to determine the reactor power as a function of reactivity insertion rate in the presence of neutron source. The analytical solution is a combination of converging two infinite series. Truncated infinite series is the analytical solution of P.K E. A general formulation is made by Combining both the ramp reactivity and step reactivity solution. So that the analytical solution could be useful in analyzing either step and ramp reactivity insertion exclusively or the combination of both. This general formulation could be useful in analyzing many reactor operations, like the air bubble passing through the core, stuck rod conditions, uncontrolled withdrawal of controlled rod, discontinuous lifting of control rod, lowering of rod and etc. Results of analytical solutions are compared against the results of numerical solution which is developed based on Cohen's method. The comparisons are found to be good for all kind of positive and negative ramp reactivity insertions, with or without the combination of step reactivity

  15. An analytical dynamo solution for large-scale magnetic fields of galaxies

    CERN Document Server

    Chamandy, Luke

    2016-01-01

    We present an effectively global analytical asymptotic galactic dynamo solution for the regular magnetic field of an axisymmetric thin disc in the saturated state. This solution is constructed by combining two well-known types of local galactic dynamo solution, parameterized by the disc radius. Namely, the critical (zero growth) solution obtained by treating the dynamo equation as a perturbed diffusion equation is normalized using a non-linear solution that makes use of the `no-$z$' approximation and the dynamical $\\alpha$-quenching non-linearity. This overall solution is found to be reasonably accurate when compared with detailed numerical solutions. It is thus potentially useful as a tool for predicting observational signatures of magnetic fields of galaxies. In particular, such solutions could be painted onto galaxies in cosmological simulations to enable the construction of synthetic polarized synchrotron and Faraday rotation measure (RM) datasets. Further, we explore the properties of our numerical solut...

  16. A moving boundary solution for solidification of lava lake and magma intrusion in the presence of time-varying contact temperature

    Indian Academy of Sciences (India)

    Ajay Manglik

    2005-04-01

    During the solidification of a lava lake heat is released convectively from the top surface as well as conductively into the country rock from the base, leading to non-uniform solidification. The upper solidified layer grows at a faster rate than the lower solidified layer. Similarly, solidification of magma intrusion within the crust is also non-uniform due to the presence of thermal gradient in the crust. Available analytical solution for solidification of a melt layer assumes only symmetric cooling about the centre of the layer. In the present work a moving boundary solution for thermal evolution and non-uniform solidification of a melt layer incorporating time-varying contact temperature conditions at both of its boundaries is developed. The solution is obtained by using the Fourier spectral approach in the space domain and a modified finite difference scheme in the time domain, and is validated with available analytical solutions for simple cases and a semi-analytical solution for the case involving temperature gradient in the country rock. This solution can be used to analyse solidification of lava lakes and magma intrusions experiencing time-dependent temperature variation at their contacts with the country rock.

  17. Analytical Solution for the SU(2) Hedgehog Skyrmion and Static Properties of Nucleons

    CERN Document Server

    Jia, Duojie; Liu, Feng

    2009-01-01

    An analytical solution for symmetric Skyrmion was proposed for the SU(2) Skyrme model, which take the form of the hybrid form of a kink-like solution and that given by the instanton method. The static properties of nucleons was then computed within the framework of collective quantization of the Skyrme model, with a good agreement with that given by the exact numeric solution. The comparisons with the previous results as well as the experimental values are also given.

  18. A Study of Analytics Driven Solutions for Customer Targeting and Sales Force Allocation in Data Mining

    OpenAIRE

    Santosh Soni

    2011-01-01

    OnTARGET and MAP are examples of analytics-based solutions that were designed from the outset to address specific business challenges in the broad area of sales force productivity. Although they address different underlying issues, these solutions implement a common approach that is generally applicable to a broad class of operational challenges. Both solutions rely on rigorously defined data models that integrate all relevant data into a common database. Choices of the data to be included in...

  19. Abrupt PN junctions: Analytical solutions under equilibrium and non-equilibrium

    Science.gov (United States)

    Khorasani, Sina

    2016-08-01

    We present an explicit solution of carrier and field distributions in abrupt PN junctions under equilibrium. An accurate logarithmic numerical method is implemented and results are compared to the analytical solutions. Analysis of results shows reasonable agreement with numerical solution as well as the depletion layer approximation. We discuss extensions to the asymmetric junctions. Approximate relations for differential capacitance C-V and current-voltage I-V characteristics are also found under non-zero external bias.

  20. The anatomy of grain boundaries: Their structure and atomic-level solute distribution

    International Nuclear Information System (INIS)

    The full macroscopic parameters of grain boundaries in a nanostructured ferritic alloy have been experimentally measured. A new atom-probe-tomography-based method determines the five degrees of freedom of the orientation relationship of the adjacent grains, and the local variations in the habit plane and solute excesses for tungsten and chromium across the grain boundary with a spatial resolution of up to 1 nm × 1 nm. The method also distinguishes ultrafine precipitates and ferrite–ferrite regions for a full description of the grain boundary

  1. Solution matching for a three-point boundary-value problem on atime scale

    Directory of Open Access Journals (Sweden)

    Martin Eggensperger

    2004-07-01

    Full Text Available Let $mathbb{T}$ be a time scale such that $t_1, t_2, t_3 in mathbb{T}$. We show the existence of a unique solution for the three-point boundary value problem $$displaylines{ y^{DeltaDeltaDelta}(t = f(t, y(t, y^Delta(t, y^{DeltaDelta}(t, quad t in [t_1, t_3] cap mathbb{T},cr y(t_1 = y_1, quad y(t_2 = y_2, quad y(t_3 = y_3,. }$$ We do this by matching a solution to the first equation satisfying a two-point boundary conditions on $[t_1, t_2] cap mathbb{T}$ with a solution satisfying a two-point boundary conditions on $[t_2, t_3] cap mathbb{T}$.

  2. A fully nonlinear iterative solution method for self-similar potential flows with a free boundary

    CERN Document Server

    Iafrati, Alessandro

    2013-01-01

    An iterative solution method for fully nonlinear boundary value problems governing self-similar flows with a free boundary is presented. Specifically, the method is developed for application to water entry problems, which can be studied under the assumptions of an ideal and incompressible fluid with negligible gravity and surface tension effects. The approach is based on a pseudo time stepping procedure, which uses a boundary integral equation method for the solution of the Laplace problem governing the velocity potential at each iteration. In order to demonstrate the flexibility and the capabilities of the approach, several applications are presented: the classical wedge entry problem, which is also used for a validation of the approach, the block sliding along an inclined sea bed, the vertical water entry of a flat plate and the ditching of an inclined plate. The solution procedure is also applied to cases in which the body surface is either porous or perforated. Comparisons with numerical or experimental d...

  3. Analytical solution of electrohydrodynamic flow and transport in rectangular channels: inclusion of double layer effects

    KAUST Repository

    Joekar-Niasar, V.

    2013-01-25

    Upscaling electroosmosis in porous media is a challenge due to the complexity and scale-dependent nonlinearities of this coupled phenomenon. "Pore-network modeling" for upscaling electroosmosis from pore scale to Darcy scale can be considered as a promising approach. However, this method requires analytical solutions for flow and transport at pore scale. This study concentrates on the development of analytical solutions of flow and transport in a single rectangular channel under combined effects of electrohydrodynamic forces. These relations will be used in future works for pore-network modeling. The analytical solutions are valid for all regimes of overlapping electrical double layers and have the potential to be extended to nonlinear Boltzmann distribution. The innovative aspects of this study are (a) contribution of overlapping of electrical double layers to the Stokes flow as well as Nernst-Planck transport has been carefully included in the analytical solutions. (b) All important transport mechanisms including advection, diffusion, and electromigration have been included in the analytical solutions. (c) Fully algebraic relations developed in this study can be easily employed to upscale electroosmosis to Darcy scale using pore-network modeling. © 2013 Springer Science+Business Media Dordrecht.

  4. Commentary on local and boundary regularity of weak solutions to Navier-Stokes equations

    Directory of Open Access Journals (Sweden)

    Zdenek Skalak

    2004-01-01

    Full Text Available We present results on local and boundary regularity for weak solutions to the Navier-Stokes equations. Beginning with the regularity criterion proved recently in [14] for the Cauchy problem, we show that this criterion holds also locally. This is also the case for some other results: We present two examples concerning the regularity of weak solutions stemming from the regularity of two components of the vorticity ([2] or from the regularity of the pressure ([3]. We conclude by presenting regularity criteria near the boundary based on the results in [10] and [16].

  5. POSITIVE SOLUTIONS OF A NONLINEAR THREE-POINT EIGENVALUE PROBLEM WITH INTEGRAL BOUNDARY CONDITIONS

    Directory of Open Access Journals (Sweden)

    FAOUZI HADDOUCHI

    2015-11-01

    Full Text Available In this paper, we study the existence of positive solutions of a three-point integral boundary value problem (BVP for the following second-order differential equation u''(t + \\lambda a(tf(u(t = 0; 0 0 is a parameter, 0 <\\eta < 1, 0 <\\alpha < 1/{\\eta}. . By using the properties of the Green's function and Krasnoselskii's fixed point theorem on cones, the eigenvalue intervals of the nonlinear boundary value problem are considered, some sufficient conditions for the existence of at least one positive solutions are established.

  6. Analytical solutions for non-linear differential equations with the help of a digital computer

    Science.gov (United States)

    Cromwell, P. C.

    1964-01-01

    A technique was developed with the help of a digital computer for analytic (algebraic) solutions of autonomous and nonautonomous equations. Two operational transform techniques have been programmed for the solution of these equations. Only relatively simple nonlinear differential equations have been considered. In the cases considered it has been possible to assimilate the secular terms into the solutions. For cases where f(t) is not a bounded function, a direct series solution is developed which can be shown to be an analytic function. All solutions have been checked against results obtained by numerical integration for given initial conditions and constants. It is evident that certain nonlinear differential equations can be solved with the help of a digital computer.

  7. Fourier solution of two-dimensional Navier Stokes equation with periodic boundary conditions and incompressible flow

    CERN Document Server

    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.

  8. A comment on the importance of numerical evaluation of analytic solutions involving approximations.

    Science.gov (United States)

    Overall, J E; Starbuck, R R; Doyle, S R

    1994-07-01

    An analytic solution proposed by Senn (1) for removing the effects of covariate imbalance in controlled clinical trials was subjected to Monte Carlo evaluation. For practical applications of his derivation, Senn proposed substitution of sample statistics for parameters of the bivariate normal model. Unfortunately, that substitution produces severe distortion in the size of tests of significance for treatment effects when covariate imbalance is present. Numerical verification of proposed substitutions into analytic models is recommended as a prudent approach. PMID:7951276

  9. An Approximate Analytical Solution of Sloshing Frequencies for a Liquid in Various Shape Aqueducts

    OpenAIRE

    Yuchun Li; Zhuang Wang

    2014-01-01

    An approximate analytical solution of sloshing frequencies for a liquid in the various shape aqueducts is formulated by using the Ritz method. The present approximate method is, respectively, applied to find the sloshing frequencies of the liquid in rectangular, trapezoid, oval, circular, U-shaped tanks (aqueducts), and various shape tuned liquid dampers (TLD). The first three antisymmetric and symmetric frequencies by the present approach are within 5% accuracy compared to the other analytic...

  10. Analytical Solution of the Blast Wave Problem in a Non-Ideal Gas

    International Nuclear Information System (INIS)

    An analytical approach is used to construct the exact solution of the blast wave problem with generalized geometries in a non-ideal medium. It is assumed that the density ahead of the shock front varies according to a power of distance from the source of the blast wave. Also, an analytical expression for the total energy in a non-ideal medium is derived. (fundamental areas of phenomenology(including applications))

  11. An Analytical Solution for Transient Thermal Response of an Insulated Structure

    Science.gov (United States)

    Blosser, Max L.

    2012-01-01

    An analytical solution was derived for the transient response of an insulated aerospace vehicle structure subjected to a simplified heat pulse. This simplified problem approximates the thermal response of a thermal protection system of an atmospheric entry vehicle. The exact analytical solution is solely a function of two non-dimensional parameters. A simpler function of these two parameters was developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Using these techniques, the maximum structural temperature rise was calculated using the analytical solutions and shown to typically agree with finite element simulations within 10 to 20 percent over the relevant range of parameters studied.

  12. Some analytic solutions for stochastic reactor models based on the joint composition PDF

    Science.gov (United States)

    Kraft, Markus; Fey, Harald

    1999-06-01

    The stochastic reactor models, partially stirred reactor (PaSR) and partially stirred plug flow reactor (PaSPFR) have been investigated. These models are based on a simplified joint composition PDF transport equation. Analytic solutions for five different Cauchy problems for the PDF transport equation as given by the stochastic reactor models are presented. In all cases, molecular mixing in the stochastic reactor models is described by the linear mean-square estimation (LMSE) mixing model for turbulent diffusion. The analytic solutions have been found by combining the method of characteristics with a set of ordinary differential equations for the statistical moments to account for the functional dependence of the coefficients in the corresponding PDF transport equation. For each case an example problem is discussed to illustrate the behaviour of the analytic solution.

  13. Analytic Solutions of a Second-Order Iterative Functional Differential Equations

    Science.gov (United States)

    Liu, Lingxia

    In this paper, the existence of analytic solutions of an iterative functional differential equation is studied. We reduce this problem to finding analytic solutions of a functional differential equation without iteration of the unknown function. For technical reasons, in previous work the constant α given in Schröder transformation is required to fulfill that α is off the unit circle or lies on the circle with the Diophantine condition. In this paper, we break the restraint of the Diophantine condition and obtain results of analytic solutions in the case of α at resonance, i.e., at a root of the unity and the case of α near resonance under the Brjuno condition.

  14. An analytical solution for transverse thermal conductivities of unidirectional fibre composites with thermal barrier

    Energy Technology Data Exchange (ETDEWEB)

    Zou Mingqing; Zhang Duanming; Yu Boming [Department of Physics and the State Key Laboratory of Laser, Huazhong University of Science and Technology, Wuhan (China)]. E-mail: yu3838@public.wh.hb.cn

    2002-08-07

    In this paper, an analytical expression for transverse thermal conductivities of unidirectional fibre composites with thermal barrier is derived based on the electrical analogy technique and on the cylindrical filament-square packing array unit cell model (C-S model). The present analytical expressions both with and without thermal barrier between fibre and matrix are presented. The present theoretical predictions without thermal barrier are found to be in excellent agreement with the existing analytical model and nomogram from the finite difference method (FDM), and in good agreement with existing experimental data. Furthermore, the present analytical predictions with thermal barrier can best fit the experimental data and can provide a higher accuracy than the finite element method (FEM). The validity of the present analytical solution is thus verified for transverse thermal conductivities of unidirectional fibre composites with thermal barrier. (author)

  15. An analytical solution for transverse thermal conductivities of unidirectional fibre composites with thermal barrier

    International Nuclear Information System (INIS)

    In this paper, an analytical expression for transverse thermal conductivities of unidirectional fibre composites with thermal barrier is derived based on the electrical analogy technique and on the cylindrical filament-square packing array unit cell model (C-S model). The present analytical expressions both with and without thermal barrier between fibre and matrix are presented. The present theoretical predictions without thermal barrier are found to be in excellent agreement with the existing analytical model and nomogram from the finite difference method (FDM), and in good agreement with existing experimental data. Furthermore, the present analytical predictions with thermal barrier can best fit the experimental data and can provide a higher accuracy than the finite element method (FEM). The validity of the present analytical solution is thus verified for transverse thermal conductivities of unidirectional fibre composites with thermal barrier. (author)

  16. Existence of positive solutions to a Laplace equation with nonlinear boundary condition

    Science.gov (United States)

    Kim, C.-G.; Liang, Z.-P.; Shi, J.-P.

    2015-12-01

    The positive solutions of a Laplace equation with a superlinear nonlinear boundary condition on a bounded domain are studied. For higher-dimensional domains, it is shown that non-constant positive solutions bifurcate from a branch of trivial solutions at a sequence of bifurcation points, and under additional conditions on nonlinearity, the existence of a non-constant positive solution for any sufficiently large parameter value is proved by using variational approach. It is also proved that for one-dimensional domain, there is only one bifurcation point, all non-constant positive solutions lie on the bifurcating curve, and for large parameter values, there exist at least two non-constant positive solutions. For a special case, there are exactly two non-constant positive solutions.

  17. An analytical solution to a simplified EDXRF model for Monte Carlo code verification

    International Nuclear Information System (INIS)

    The objective of this study is to obtain an analytical solution to the scalar photon transport equation that can be used to obtain benchmark results for the verification of energy dispersive X-Ray fluorescence (EDXRF) Monte Carlo simulation codes. The multi-collided flux method (multiple scattering method) is implemented to obtain analytical expressions for the space-, energy-, and angle-dependent scalar photon flux for a one dimensional EDXRF model problem. In order to obtain benchmark results, higher-order multiple scattering terms are included in the multi-collided flux method. The details of the analytical solution and of the proposed EDXRF model problem are presented. Analytical expressions obtained are then used to calculate the energy-dependent current. The analytically-calculated energy-dependent current is compared with Monte Carlo code results. The findings of this study show that analytical solutions to the scalar photon transport equation with the proposed model problem can be used as a verification tool in EDXRF Monte Carlo code development.

  18. On the Analytical Solution of Non-Orthogonal Stagnation Point Flow towards a Stretching Sheet

    DEFF Research Database (Denmark)

    Kimiaeifar, Amin; Bagheri, G. H.; Barari, Amin; Arabsolghar, A. R.; Rahimpour, M.

    2011-01-01

    the literature and are solved analytically by means of the Homotopy Analysis Method (HAM). The comparison of results from this paper and those published in the literature confirms the precise accuracy of the HAM. The resulting analytical equation from HAM is valid for entire physical domain and......An analytical solution for non-orthogonal stagnation point for the steady flow of a viscous and incompressible fluid is presented. The governing nonlinear partial differential equations for the flow field are reduced to ordinary differential equations by using similarity transformations existed in...

  19. Corrected Analytical Solution of the Generalized Woods-Saxon Potential for Arbitrary $\\ell$ States

    CERN Document Server

    Bayrak, O

    2015-01-01

    The bound state solution of the radial Schr\\"{o}dinger equation with the generalized Woods-Saxon potential is carefully examined by using the Pekeris approximation for arbitrary $\\ell$ states. The energy eigenvalues and the corresponding eigenfunctions are analytically obtained for different $n$ and $\\ell$ quantum numbers. The obtained closed forms are applied to calculate the single particle energy levels of neutron orbiting around $^{56}$Fe nucleus in order to check consistency between the analytical and Gamow code results. The analytical results are in good agreement with the results obtained by Gamow code for $\\ell=0$.

  20. Corrected analytical solution of the generalized Woods–Saxon potential for arbitrary ℓ states

    International Nuclear Information System (INIS)

    The bound state solution of the radial Schrödinger equation with the generalized Woods–Saxon potential is carefully examined using the Pekeris approximation for arbitrary ℓ states. The energy eigenvalues and the corresponding eigenfunctions are analytically obtained for different n and ℓ quantum numbers. The closed forms obtained are applied to calculate the single particle energy levels of a neutron orbiting around 56Fe nucleus in order to check the consistency between the analytical and the Gamow code results. The analytical results are in good agreement with the results obtained using Gamow code for ℓ=0. (paper)

  1. Solutions to fourth-order random differential equations with periodic boundary conditions

    Directory of Open Access Journals (Sweden)

    Xiaoling Han

    2012-12-01

    Full Text Available Existence of solutions and of extremal random solutions are proved for periodic boundary-value problems of fourth-order ordinary random differential equations. Our investigation is done in the space of continuous real-valued functions defined on closed and bounded intervals. Also we study the applications of the random version of a nonlinear alternative of Leray-Schauder type and an algebraic random fixed point theorem by Dhage.

  2. Positive solutions for a nonlinear periodic boundary-value problem with a parameter

    Directory of Open Access Journals (Sweden)

    Jingliang Qiu

    2012-08-01

    Full Text Available Using topological degree theory with a partially ordered structure of space, sufficient conditions for the existence and multiplicity of positive solutions for a second-order nonlinear periodic boundary-value problem are established. Inspired by ideas in Guo and Lakshmikantham [6], we study the dependence of positive periodic solutions as a parameter approaches infinity, $$ lim_{lambdao +infty}|x_{lambda}|=+infty,quadhbox{or}quad lim_{lambdao+infty}|x_{lambda}|=0. $$

  3. Analytic solution and pulse area theorem for three-level atoms

    Science.gov (United States)

    Shchedrin, Gavriil; O'Brien, Chris; Rostovtsev, Yuri; Scully, Marlan O.

    2015-12-01

    We report an analytic solution for a three-level atom driven by arbitrary time-dependent electromagnetic pulses. In particular, we consider far-detuned driving pulses and show an excellent match between our analytic result and the numerical simulations. We use our solution to derive a pulse area theorem for three-level V and Λ systems without making the rotating wave approximation. Formulated as an energy conservation law, this pulse area theorem can be used to understand pulse propagation through three-level media.

  4. Domains of analyticity for response solutions in strongly dissipative forced systems

    International Nuclear Information System (INIS)

    We study the ordinary differential equation εx¨+x.+εg(x)=εf(ωt), where g and f are real-analytic functions, with f quasi-periodic in t with frequency vector ω. If c0∈R is such that g(c0) equals the average of f and g′(c0) ≠ 0, under very mild assumptions on ω there exists a quasi-periodic solution close to c0 with frequency vector ω. We show that such a solution depends analytically on ε in a domain of the complex plane tangent more than quadratically to the imaginary axis at the origin

  5. Analytical solutions of nonlinear Schrödinger equation with distributed coefficients

    International Nuclear Information System (INIS)

    We combine the F-expansion method with the homogeneous balance principle to build a strategy to find analytical solitonic and periodic wave solutions to a generalized nonlinear Schrödinger equation with distributed coefficients, linear gain/loss, and nonlinear gain/absorption. In the case of a dimensionless effective Gross–Pitaevskii equation which describes the evolution of the wave function of a quasi-one-dimensional cigar-shaped Bose–Einstein condensate, the building strategy is applied to generate analytical solutions

  6. An exact analytical solution for the interstellar magnetic field in the vicinity of the heliosphere

    CERN Document Server

    Röken, Christian; Fichtner, Horst

    2014-01-01

    An analytical representation of the interstellar magnetic field in the vicinity of the heliosphere is derived. The three-dimensional field structure close to the heliopause is calculated as a solution of the induction equation under the assumption that it is frozen into a prescribed plasma flow resembling the characteristic interaction of the solar wind with the local interstellar medium. The usefulness of this analytical solution as an approximation to self-consistent magnetic field configurations obtained numerically from the full MHD equations is illustrated by quantitative comparisons.

  7. Analytical solutions of steady vibration of free rectangular plate on semi-infinite elastic foundation

    Institute of Scientific and Technical Information of China (English)

    WANG Chun-ling; HUANG Yi; JIA Ji-hong

    2007-01-01

    The method of double Fourier transform was employed in the analysis of the semi-infinite elastic foundation with vertical load. And an integral representations for the displacements of the semi-infinite elastic foundation was presented. The analytical solution of steady vibration of an elastic rectangle plate with four free edges on the semi-infinite elastic foundation was also given by combining the analytical solution of the elastic rectangle plate with the integral representation for displacements of the semiinfinite elastic foundation. Some computational results and the analysis on the influence of parameters were presented.

  8. An Approximate Analytical Solution of Sloshing Frequencies for a Liquid in Various Shape Aqueducts

    Directory of Open Access Journals (Sweden)

    Yuchun Li

    2014-01-01

    Full Text Available An approximate analytical solution of sloshing frequencies for a liquid in the various shape aqueducts is formulated by using the Ritz method. The present approximate method is, respectively, applied to find the sloshing frequencies of the liquid in rectangular, trapezoid, oval, circular, U-shaped tanks (aqueducts, and various shape tuned liquid dampers (TLD. The first three antisymmetric and symmetric frequencies by the present approach are within 5% accuracy compared to the other analytical, numerical, and experimental values. The approximate solutions of this paper for the various shape aqueducts are acceptable to the engineering applications.

  9. Algebraically explicit analytical solutions of unsteady conduction with variable thermal properties in cylindrical coordinate

    Institute of Scientific and Technical Information of China (English)

    CAI Ruixian; ZHANG Na

    2004-01-01

    The analytical solutions of unsteady heat conduction with variable thermal properties(thermal conductivity,density and specific heat are functions of temperature or coordinates)are meaningful in theory.In addition,they are very useful to the computational heat conduction to check the numerical solutions and to develop numerical schemes,grid generation methods and so forth.Such solutions in rectangular coordinates have been derived by the authors.Some other solutions for 1-D and 2-D axisymmetrical heat conduction in cylin drical coordinates are given in this paper to promote the heat conduction theory and to develop the relative computational heat conduction.

  10. A formal derivation for the Blasius similarity solution for flat-plate boundary layer

    Science.gov (United States)

    Lin, Hao

    2015-11-01

    The Blasius solution is a classical solution for a laminar boundary layer attached to a semi-infinite flat plate. The key of the solution strategy is to reduce the boundary layer equations, which are PDEs, to a set of ODEs, using a similarity variable transform. Conceptually, the similarity suggests that the velocity profile in each transverse cross-section appears ``self-similar''. In many classical text books and typical classroom lectures on fluid mechanics, the existence of the similarity solution is argued heuristically. The similarity variable is defined a priori so as to collapse the PDEs. It appears somewhat mystical that the PDEs can be perfectly reduced via such an approach. Here we present a rigorous derivation for the existence of a similarity solution, which naturally arises from the fact that there is no apparent streamwise length scale for a semi-infinite plate. Conversely, a similarity solution cannot exist if the plate size is finite. This derivation can be useful in fluids education, in topics including similarity, scaling arguments, and boundary layer theory.

  11. Multiple Positive Solutions of Boundary Value Problems for Systems of Nonlinear Third-Order Differential Equations

    Institute of Scientific and Technical Information of China (English)

    Yaohong LI; Xiaoyan ZHANG

    2013-01-01

    In this paper,we consider boundary value problems for systems of nonlinear thirdorder differential equations.By applying the fixed point theorems of cone expansion and compression of norm type and Leggett-Williams fixed point theorem,the existence of multiple positive solutions is obtained.As application,we give some examples to demonstrate our results.

  12. Existence of global solutions to free boundary value problems for bipolar Navier-Stokes-Possion systems

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2013-09-01

    Full Text Available In this article, we consider the free boundary value problem for one-dimensional compressible bipolar Navier-Stokes-Possion (BNSP equations with density-dependent viscosities. For general initial data with finite energy and the density connecting with vacuum continuously, we prove the global existence of the weak solution. This extends the previous results for compressible NS [27] to NSP.

  13. Nodal Solutions for a Class of Fourth-Order Two-Point Boundary Value Problems

    OpenAIRE

    Xu Jia; Han XiaoLing

    2010-01-01

    We consider the fourth-order two-point boundary value problem , , , where is a parameter, is given constant, with on any subinterval of , satisfies for all , and , , for some . By using disconjugate operator theory and bifurcation techniques, we establish existence and multiplicity results of nodal solutions for the above problem.

  14. Positive Solutions for a Class of Coupled System of Singular Three-Point Boundary Value Problems

    OpenAIRE

    Naseer Ahmad Asif; Rahmat Ali Khan

    2009-01-01

    Existence of positive solutions for a coupled system of nonlinear three-point boundary value problems of the type , , , , , , , is established. The nonlinearities , are continuous and may be singular at , and/or , while the parameters , satisfy . An example is also included to show the applicability of our result.

  15. Triple fixed-sign solutions in modelling a system with Hermite boundary conditions

    OpenAIRE

    Wong Patricia JY; Soh YC

    2005-01-01

    We consider the following system of differential equations , , together with Hermite boundary conditions , , , , where , for , and . By using different fixed point theorems, we offer criteria for the existence of three solutions of the system which are of "prescribed signs" on the interval .

  16. Existence and uniqueness of solutions for nonlinear hyperbolic fractional differential equation with integral boundary conditions

    Directory of Open Access Journals (Sweden)

    Brahim Tellab

    2016-01-01

    Full Text Available In this paper, we investigate the existence and uniqueness of solutions for second order nonlinear fractional differential equation with integral boundary conditions. Our result is an application of the Banach contraction principle and the Krasnoselskii fixed point theorem.

  17. Periodic solutions of the quasilinear equation of forced beam vibrations with homogeneous boundary conditions

    Science.gov (United States)

    Rudakov, I. A.

    2015-10-01

    We prove the existence of a countable family of time-periodic solutions of the quasilinear equation of beam vibrations with homogeneous boundary conditions and time-periodic right-hand side in the case when the non-linear term has power growth.

  18. On Strong Solutions of Regularized Model of a Viscoelastic Medium with Variable Boundary

    OpenAIRE

    Vladimir Orlov

    2012-01-01

    We consider the initial-value problem for systems of equations describing the evolution of a viscoelastic medium with variable boundary with memory along the trajectories of a velocity field, which generalizes the Navier-Stokes system of equations. Nonlocal existence and uniqueness theorem of strong solutions containing senior square-integrable derivatives in the planar case are established.

  19. L^p-continuity of solutions to parabolic free boundary problems

    Directory of Open Access Journals (Sweden)

    Abdeslem Lyaghfouri

    2015-07-01

    Full Text Available In this article, we consider a class of parabolic free boundary problems. We establish some properties of the solutions, including L^infinity-regularity in time and a monotonicity property, from which we deduce strong L^p-continuity in time.

  20. POSITIVE SOLUTIONS TO A SECOND-ORDER m-POINT BOUNDARY VALUE PROBLEM ON TIME SCALES

    Institute of Scientific and Technical Information of China (English)

    Liu Yang; Chunfang Shen

    2009-01-01

    By a fixed point theorem in a cone,the existence of at least three positive solutions to a class of second-order multi-point boundary value problem for dynamic equation on time scales with the nonlinear term depends on the first order derivative is studied.

  1. Calculating methods of solution of boundary-value problems of mathematical physics

    Energy Technology Data Exchange (ETDEWEB)

    Skopetskii, V.V.; Deineka, V.S.; Sklepovaya, L.I. [Kiev Univ. (Ukraine)] [and others

    1994-11-10

    A new mathematical model is developed for unsteady seepage in a pressure gradient through a compressible foundation of a gravity dam with an antiseepage curtain. High-accuracy discretization algorithms are developed for the corresponding initial boundary-value problem with a discontinuous solution.

  2. Interstitial and substitutional solute segregation at individual grain boundaries of α-iron: data revisited

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel; Hofmann, S.

    2016-01-01

    Roč. 28, č. 6 (2016), s. 064001. ISSN 0953-8984 R&D Projects: GA ČR GAP108/12/0144 Institutional support: RVO:68378271 Keywords : anisotropy * enthalpy-entropy compensation effect * grain boundary * iron solute segregation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.346, year: 2014

  3. assessment of concentration of air pollutants using analytical and numerical solution of the atmospheric diffusion equation

    International Nuclear Information System (INIS)

    The mathematical formulation of numerous physical problems a results in differential equations actually partial or ordinary differential equations.In our study we are interested in solutions of partial differential equations.The aim of this work is to calculate the concentrations of the pollution, by solving the atmospheric diffusion equation(ADE) using different mathematical methods of solution. It is difficult to solve the general form of ADE analytically, so we use some assumptions to get its solution.The solutions of it depend on the eddy diffusivity profiles(k) and the wind speed u. We use some physical assumptions to simplify its formula and solve it. In the present work, we solve the ADE analytically in three dimensions using Green's function method, Laplace transform method, normal mode method and these separation of variables method. Also, we use ADM as a numerical method. Finally, comparisons are made with the results predicted by the previous methods and the observed data.

  4. The Exact General Solution of Painlev\\'e's Sixth Equation (PVI) and The Exact General Solution of the Navier Stokes Equations with Applications to Boundary Layer Problems

    CERN Document Server

    Roman-Miller, Lance Arthur

    2011-01-01

    This paper provides the first known exact general solutions of Painlev\\'e's sixth equation (PVI) and the exact general solutions of the Navier Stokes equations and Prandtl's boundary layer equations.

  5. Axially symmetric static sources: A general framework and some analytical solutions

    OpenAIRE

    Herrera, L.; Di Prisco, A.; J. Ibañez; Ospino, J.

    2013-01-01

    We provide all basic equations and concepts required to carry out a general study on axially symmetric static sources. The Einstein equations and the conservation equations are written down for a general anisotropic static fluid endowed with axial symmetry. The structure scalars are calculated and the inhomogeneity factors are identified. Finally some exact analytical solutions were found. One of these solutions describes an incompressible spheroid with isotropic pressure and becomes the well...

  6. Analytical solution for transient partitioning and reaction of a condensing vapor species in a droplet

    OpenAIRE

    Liu, Albert Tianxiang; Zaveri, Rahul A.; Seinfeld, John H.

    2014-01-01

    We present the exact analytical solution of the transient equation of gas-phase diffusion of a condensing vapor to, and diffusion and reaction in, an aqueous droplet. Droplet-phase reaction is represented by first-order chemistry. The solution facilitates study of the dynamic nature of the vapor uptake process as a function of droplet size, Henry's law coefficient, and first-order reaction rate constant for conversion in the droplet phase.

  7. Analytical solution of point kinetic equations for sub-critical systems

    International Nuclear Information System (INIS)

    This article presents an analytical solution for the set of point kinetic equations for sub-critical reactors. This solution stems from the ordinary, non-homogeneous differential equation that rules the neutron density and that presents the incomplete Gamma function in its functional form. The method used proved advantageous and allowed practical applications such as the linear insertion of reactivity, considering an external constant source or with both varying linearly. (author)

  8. Analytical solution of Stokes flow inside an evaporating sessile drop: Spherical and cylindrical cap shapes

    OpenAIRE

    Masoud, Hassan; James D. Felske

    2008-01-01

    Exact analytical solutions are derived for the Stokes flows within evaporating sessile drops of spherical and cylindrical cap shapes. The results are valid for arbitrary contact angle. Solutions are obtained for arbitrary evaporative flux distributions along the free surface as long as the flux is bounded at the contact line. The field equations, E^4(Psi)=0 and Del^4(Phi)=0, are solved for the spherical and cylindrical cap cases, respectively. Specific results and computations are presented f...

  9. A hybrid approach to the solution of open boundary eddy current problems under TM field excitation

    International Nuclear Information System (INIS)

    This paper extends the modified hybrid integrodifferential finite element (IDFE) Green's function method to the solution of 2D unbounded eddy current problems under transverse magnetic (TM) field excitation. To illustrate this formulation, the magnetic vector potentials (MVP) of a solid and a hollow conducting cylinder under TM field excitations are computed. Current distributions and power losses are obtained. The formulation is validated by comparing calculated results with analytic solutions

  10. A SEMI-ANALYTICAL SOLUTION FOR CHARACTERISTICS OF A DAM-RESERVOIR SYSTEM WITH ABSORPTIVE RESERVOIR BOTTOM

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this study, a semi-analytical formulation based on the Scaled Boundary Finite Element Method (SBFEM) was proposed and used to obtain the solution for the characteristics of a two-dimensional dam-reservoir system with absorptive reservoir bottom in the frequency domain. For simplicity, the dam with arbitrary upstream faces was assumed to be rigid and was subjected to a horizontal ground acceleration, while the reservoir with absorptive bottom was assumed to be semi-infinite. The reservoir was divided into two sub-domains: a near-field sub-domain and a far-field sub-domain. The near-field sub-domain with arbitrary geometry was modelled by the Finite Element Method (FEM), while the effects of the far-field sub-domain which was assumed to be horizontal were described by a semi-analytical formation. The semi-analytical formulation involved the effect of absorptive reservoir bottom, as well as the radiation damping effect of a semi-infinite reservoir. A FEM/SBFEM coupling formulation was presented to solve dam-reservoir coupled problems. The accuracy and efficiency of the coupling formulation were demonstrated by computing some benchmark examples. Highly accurate results are produced even if the near-field sub-domain is very small.

  11. A Semi-Analytical Solution for Large-Scale Injection-Induced PressurePerturbation and Leakage in a Laterally Bounded Aquifer-AquitardSystem

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Quanlin; Birkholzer, Jens T.; Tsang, Chin-Fu

    2008-07-15

    A number of (semi-)analytical solutions are available to drawdown analysis and leakage estimation of shallow aquifer-aquitard systems. These solutions assume that the systems are laterally infinite. When a large-scale pumping from (or injection into) an aquifer-aquitard system of lower specific storativity occurs, induced pressure perturbation (or hydraulic head drawdown/rise) may reach the lateral boundary of the aquifer. We developed semi-analytical solutions to address the induced pressure perturbation and vertical leakage in a 'laterally bounded' system consisting of an aquifer and an overlying/underlying aquitard. A one-dimensional radial flow equation for the aquifer was coupled with a one-dimensional vertical flow equation for the aquitard, with a no-flow condition imposed on the outer radial boundary. Analytical solutions were obtained for (1) the Laplace-transform hydraulic head drawdown/rise in the aquifer and in the aquitard, (2) the Laplace-transform rate and volume of leakage through the aquifer-aquitard interface integrated up to an arbitrary radial distance, (3) the transformed total leakage rate and volume for the entire interface, and (4) the transformed horizontal flux at any radius. The total leakage rate and volume depend only on the hydrogeologic properties and thicknesses of the aquifer and aquitard, as well as the duration of pumping or injection. It was proven that the total leakage rate and volume are independent of the aquifer's radial extent and wellbore radius. The derived analytical solutions for bounded systems are the generalized solutions of infinite systems. Laplace-transform solutions were numerically inverted to obtain the hydraulic head drawdown/rise, leakage rate, leakage volume, and horizontal flux for given hydrogeologic and geometric conditions of the aquifer-aquitard system, as well as injection/pumping scenarios. Application to a large-scale injection-and-storage problem in a bounded system was demonstrated.

  12. Solutions of atmospheric dispersion equation and parameters in the boundary layer

    International Nuclear Information System (INIS)

    There is an increasing interest in studies of atmospheric aerosols in the context of their impact and atmospheric chemistry associated. In this work attention was paid to mathematical relationship to evaluate air dispersion concentrations under different conditions.The material in the present thesis is organized in three chapters in the following way:In chapter (1), we describe as. In section 1-1, General introduction. In section 1-2. Study atmosphere boundary layer, in section 1-3.Study atmospheric diffusion, In section 1-4, defined the concentration, In section 1-5, Defined the dispersion and diffusion .In section 6.Characterization of Turbulent Diffusion.In chapter (2), we derive a simple solution of the steady state, dimensional diffusion equation that describes advection in the direction of the wind and diffusion in the vertical direction using separation method. The separation method has been found to give solution, which agrees well with observed concentration of sulfur dioxide. In section 1, we study the mathematically analogous problem of dispersal pollution over area sources. In section 2-2, we give a description of the analytical method, In section 2-3, we give a description of the numerical method while in section 2-4 and 2-5, we give an application of the method to the calculation of dispersal of sulfur dioxide in a 2-h, steady state period in the atmosphere of Nashville. Tennessee.In chapter (3), we estimated the concentration of PM10 (where it is the portion of particulate matter in the air having an aerodynamic equivalent diameter (AED) less than or equal to 10 μm) and compare horizontal flux calculations presented by (Veranth et al. (2003)) with emissions measured from a dispersion model applied to the same data. The next section is used to study the system of computing Horizontal fluxes. In section 3-2, using the mathematical techniques to derived the parameters such as the expressions and the mean plume velocity (where the mathematical

  13. On the analytical solution of Fornberg–Whitham equation with the new fractional derivative

    Indian Academy of Sciences (India)

    Olaniyi Samuel Iyiola; Gbenga Olayinka Ojo

    2015-10-01

    Motivated by the simplicity, natural and efficient nature of the new fractional derivative introduced by R Khalil et al in J. Comput. Appl. Math. 264, 65 (2014), analytical solution of space-time fractional Fornberg–Whitham equation is obtained in series form using the relatively new method called q-homotopy analysis method (q-HAM). The new fractional derivative makes it possible to introduce fractional order in space to the Fornberg–Whitham equation and be able to obtain its solution. This work displays the elegant nature of the application of q-HAM to solve strongly nonlinear fractional differential equations. The presence of the auxiliary parameter h helps in an effective way to obtain better approximation comparable to exact solutions. The fraction-factor in this method gives it an edge over other existing analytical methods for nonlinear differential equations. Comparisons are made on the existence of exact solutions to these models. The analysis shows that our analytical solutions converge very rapidly to the exact solutions.

  14. Boundary Element Method Solution in the Time Domain For a Moving Time-Dependent Force

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Kirkegaard, Poul Henning; Rasmussen, K. M.

    2001-01-01

    The problem of a moving time dependent concentrated force on the surface of an elastic halfspace is of interest in the analysis of traffic generated noise. The Boundary element method (BEM) is superior to the finite element method (FEM) in solving such problems due to its inherent ability so...... satisfy the radiation conditions exactly. In this paper a model based on the BEM is formulated for the solution of the mentioned problem. A numerical solution is obtained for the 2D plane strain case, and comparison is made with the results obtained from a corresponding FEM solution with an impedance...

  15. Closed-form analytical solutions for assessing the consequences of sea-level rise on unconfined sloping island aquifers

    Science.gov (United States)

    Chesnaux, R.

    2016-04-01

    Closed-form analytical solutions for assessing the consequences of sea-level rise on fresh groundwater oceanic island lenses are provided for the cases of both strip and circular islands. Solutions are proposed for directly calculating the change in the thickness of the lens, the changes in volume and the changes in travel time of fresh groundwater within island aquifers. The solutions apply for homogenous aquifers recharged by surface infiltration and discharged by a down-gradient, fixed-head boundary. They also take into account the inland shift of the ocean due to land surface inundation, this shift being determined by the coastal slope of inland aquifers. The solutions are given for two simple island geometries: circular islands and strip islands. Base case examples are presented to illustrate, on one hand, the amplitude of the change of the fresh groundwater lens thickness and the volume depletion of the lens in oceanic island with sea-level rise, and on the other hand, the shortening of time required for groundwater to discharge into the ocean. These consequences can now be quantified and may help decision-makers to anticipate the effects of sea-level rise on fresh groundwater availability in oceanic island aquifers.

  16. On the asymptotic of solutions of elliptic boundary value problems in domains with edges

    International Nuclear Information System (INIS)

    Solutions of elliptic boundary value problems in three-dimensional domains with edges may exhibit singularities. The usual procedure to study these singularities is by the application of the classical Mellin transformation or continuous Fourier transformation. In this paper, we show how the asymptotic behavior of solutions of elliptic boundary value problems in general three-dimensional domains with straight edges can be investigated by means of discrete Fourier transformation. We apply this approach to time-harmonic Maxwell's equations and prove that the singular solutions can fully be described in terms of Fourier series. The representation here can easily be used to approximate three-dimensional stress intensity factors associated with edge singularities. (author)

  17. On Perturbation Solutions for Axisymmetric Bending Boundary Values of a Deep Thin Spherical Shell

    Directory of Open Access Journals (Sweden)

    Rong Xiao

    2014-01-01

    Full Text Available On the basis of the general theory of elastic thin shells and the Kirchhoff-Love hypothesis, a fundamental equation for a thin shell under the moment theory is established. In this study, the author derives Reissner’s equation with a transverse shear force Q1 and the displacement component w. These basic unknown quantities are derived considering the axisymmetry of the deep, thin spherical shell and manage to constitute a boundary value question of axisymmetric bending of the deep thin spherical shell under boundary conditions. The asymptotic solution is obtained by the composite expansion method. At the end of this paper, to prove the correctness and accuracy of the derivation, an example is given to compare the numerical solution by ANSYS and the perturbation solution. Meanwhile, the effects of material and geometric parameters on the nonlinear response of axisymmetric deep thin spherical shell under uniform external pressure are also analyzed in this paper.

  18. Solution matching for a three-point boundary-value problem on atime scale

    OpenAIRE

    Martin Eggensperger; Kaufmann, Eric R.; Nickolai Kosmatov

    2004-01-01

    Let $mathbb{T}$ be a time scale such that $t_1, t_2, t_3 in mathbb{T}$. We show the existence of a unique solution for the three-point boundary value problem $$displaylines{ y^{DeltaDeltaDelta}(t) = f(t, y(t), y^Delta(t), y^{DeltaDelta}(t)), quad t in [t_1, t_3] cap mathbb{T},cr y(t_1) = y_1, quad y(t_2) = y_2, quad y(t_3) = y_3,. }$$ We do this by matching a solution to the first equation satisfying a two-point boundary conditions on $[t_1, t_2] cap mathbb{T}$ with a solut...

  19. Solution of the advection-diffusion equation for a nonhomogeneous and nonstationary Planetary Boundary Layer by GILTT (Generalized Integral Laplace Transform Technique)

    International Nuclear Information System (INIS)

    In this work is shown the solution of the advection-diffusion equation to simulate a pollutant dispersion in the Planetary Boundary Layer. The solution is obtained through of the GILTT (Generalized Integral Laplace Transform Technique) analytic method and of the numerical inversion Gauss Quadrature. The validity of the solution is proved using concentration obtained from the model with concentration obtained for Copenhagen experiment. In this comparison was utilized potential and logarithmic wind profile and eddy diffusivity derived by Degrazia et al (1997) [17] and (2002) [19]. The best results was using the potential wind profile and the eddy diffusivity derived by Degrazia et al (1997). The vertical velocity influence is shown in the plume behavior of the pollutant concentration. Moreover, the vertical and longitudinal velocity provided by Large Eddy Simulation (LES) was stood in the model to simulate the turbulent boundary layer more realistic, the result was satisfactory when compared with contained in the literature. (author)

  20. Capabilities and limitations of analytical methods used to measure radiation-induced grain boundary segregation

    International Nuclear Information System (INIS)

    The quantitative determination of instrumental effects on the measurement of radiation-induced grain boundary segregation (RIS) in stainless steel have been irradiated with 3.4 MeV protons to 1 dpa at 400 degrees C and the resulting segregation has been measured by Auger electron spectroscopy (AES) and scanning-transmission electron microscopy using energy-dispersive x-ray spectroscopy (STEM-EDS). Depletion of chromium and enrichment of nickel and impurity elements at the grain boundaries have been observed and quantified using both techniques. Determination of true grain boundary compositions, as compared to measured compositions, has been attempted using a variety of techniques Deconvolution of the measured STEM profiles is possible, along with the effects of discrete sampling at finite step spacings render the technique incapable of a reliable determination of the true grain boundary compositions. Convolution of computer simulated segregation profiles with the beam-interaction volume to fit measured profiles provides a better method to estimate the true grain boundary concentration and segregation profile shape. Direct comparisons between the simulated STEM profiles and AES measurements show good agreement and indicate that the simulated profiles provide good estimates of the true grain boundary concentration. Use of computer codes based on the Perks model are shown to seriously overestimate the amount of RIS and the width of the segregation profiles. A calculational model for monolayer-type segregation of impurities combines the STEM and AES measurements to calculate the distribution of the impurity element at the grain boundary

  1. Existence of 2m-1 Positive Solutions for Sturm-Liouville Boundary Value Problems with Linear Functional Boundary Conditions on the Half-Line

    Directory of Open Access Journals (Sweden)

    Yanmei Sun

    2012-01-01

    Full Text Available By using the Leggett-Williams fixed theorem, we establish the existence of multiple positive solutions for second-order nonhomogeneous Sturm-Liouville boundary value problems with linear functional boundary conditions. One explicit example with singularity is presented to demonstrate the application of our main results.

  2. Contribution to analytical solution of neutron slowing down problem in homogeneous and heterogeneous media

    International Nuclear Information System (INIS)

    The objective of this work is to describe the new analytical solution of the neutron slowing down equation for infinite monoatomic media with arbitrary energy dependence of cross section. The solution is obtained by introducing Green slowing down functions instead of starting from slowing down equations directly. The previously used methods for calculation of fission neutron spectra in the reactor cell were numerical. The proposed analytical method was used for calculating the space-energy distribution of fast neutrons and number of neutron reactions in a thermal reactor cell. The role of analytical method in solving the neutron slowing down in reactor physics is to enable understating of the slowing down process and neutron transport. The obtained results could be used as standards for testing the accuracy od approximative and practical methods

  3. Analytic Solution of Charge Density of Single Wall Carbon Nanotube under Conditions of Field Electron Emission

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-Bing; WANG Wei-Liang

    2006-01-01

    We derive the analytic solution of induced electrostatic potential along single wall carbon nanotubes. Under the hypothesis of constant density of states in the charge-neutral level, we are able to obtain the linear density of excess charge in an external Geld parallel to the tube axis.

  4. Analytic solution of charge density of single wall carbon nanotube in conditions of field electron emission

    OpenAIRE

    Li, Zhibing; Wang, Weiliang

    2006-01-01

    We derived the analytic solution of induced electrostatic potential along single wall carbon nanotubes. Under the hypothesis of constant density of states in the charge-neutral level, we are able to obtain the linear density of excess charge in an external field parallel to the tube axis.

  5. Analytical solutions of the Schroedinger equation with the Woods–Saxon potential for arbitrary l state

    International Nuclear Information System (INIS)

    In this work, the analytical solution of the radial Schroedinger equation for the Woods–Saxon potential is presented. In our calculations, we have applied the Nikiforov–Uvarov method by using the Pekeris approximation to the centrifugal potential for arbitrary l states. The bound state energy eigenvalues and corresponding eigenfunctions are obtained for various values of n and l quantum numbers. (author)

  6. Analytical solution for the advection-dispersion transport equation in layered media

    Science.gov (United States)

    The advection-dispersion transport equation with first-order decay was solved analytically for multi-layered media using the classic integral transform technique (CITT). The solution procedure used an associated non-self-adjoint advection-diffusion eigenvalue problem that had the same form and coef...

  7. An exact analytical solution of pool swell dynamics during depressurization by the method of characteristics

    International Nuclear Information System (INIS)

    An exact analytical solution, based on the method of characteristics, has been obtained for the spatial and temporal variation of vapor volumetric (void) fraction in a depressurizing pool. Numerical evaluations have shown that the axial void profile is strongly dependent on the drift velocity formulation, and that wall heat flux plays only a minor role in the pool swell transient. (Auth.)

  8. Analytical closed-form solution of three-phase four-switch PWM rectifier

    Czech Academy of Sciences Publication Activity Database

    Škramlík, Jiří; Valouch, Viktor; Klíma, J.; Pecha, I.

    2010-01-01

    Roč. 55, č. 3 (2010), s. 223-235. ISSN 0001-7043 R&D Projects: GA MPO FT-TA5/123 Institutional research plan: CEZ:AV0Z20570509 Keywords : four-switch PWM rectifier * space vector modulation * closed-form analytical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  9. Approximate Analytic and Numerical Solutions to Lane-Emden Equation via Fuzzy Modeling Method

    Directory of Open Access Journals (Sweden)

    De-Gang Wang

    2012-01-01

    Full Text Available A novel algorithm, called variable weight fuzzy marginal linearization (VWFML method, is proposed. This method can supply approximate analytic and numerical solutions to Lane-Emden equations. And it is easy to be implemented and extended for solving other nonlinear differential equations. Numerical examples are included to demonstrate the validity and applicability of the developed technique.

  10. A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo in Natural Waters

    Science.gov (United States)

    Several numerical and analytical solutions of the radiative transfer equation (RTE) for plane albedo were compared for solar light reflection by sea water. The study incorporated the simplest case, that being a semi-infinite one-dimensional plane-parallel absorbing and scattering...

  11. Real analytic quasi-periodic solutions for the derivative nonlinear Schrödinger equations

    Science.gov (United States)

    Geng, Jiansheng; Wu, Jian

    2012-10-01

    In this paper, we show that one dimension derivative nonlinear Schrödinger equation admits a whitney smooth family of small amplitude, real analytic quasi-periodic solutions with two Diophantine frequencies. The proof is based on a partial Birkhoff normal form reduction and an abstract infinite dimensional Kolmogorov-Arnold-Moser (KAM) theorem.

  12. Analytical solution of the linear transport equation AN approach with plane symmetry

    International Nuclear Information System (INIS)

    This work presents a new derivation of the AN approximation of the one-dimensional linear transport equation. The Kuznetsov transformation and Gaussian Quadrature scheme are employed. An analytical solution of the AN equations are also obtained using the Laplace transform. Numerical simulations are presented. (author). 8 refs, 3 tabs

  13. Application of an analytical method for solution of thermal hydraulic conservation equations

    Energy Technology Data Exchange (ETDEWEB)

    Fakory, M.R. [Simulation, Systems & Services Technologies Company (S3 Technologies), Columbia, MD (United States)

    1995-09-01

    An analytical method has been developed and applied for solution of two-phase flow conservation equations. The test results for application of the model for simulation of BWR transients are presented and compared with the results obtained from application of the explicit method for integration of conservation equations. The test results show that with application of the analytical method for integration of conservation equations, the Courant limitation associated with explicit Euler method of integration was eliminated. The results obtained from application of the analytical method (with large time steps) agreed well with the results obtained from application of explicit method of integration (with time steps smaller than the size imposed by Courant limitation). The results demonstrate that application of the analytical approach significantly improves the numerical stability and computational efficiency.

  14. Quick analytical method for the determination of iodide and iodate ions in aqueous solutions

    International Nuclear Information System (INIS)

    An analytical quick-test method was developed to determine iodide and iodate ions in aqueous solutions using solid phase extraction cartridges for sample preparation. Work was focussed on finding simple, but efficient conditions for quantitative separation of iodate and iodide. Iodine amounts were then determined by standard methods. Ion-exchange absorbers in cartridge form were used. Selectivity and yield of the species separation were studied at pH value of 5-10 and various solution compositions using 131I radioactive tracer. The electrolytes used were diluted alkaline, nitrate and boric acid-borate solutions. Application to nuclear reactor cooling water analysis or environmental investigations and monitoring is proposed. (author)

  15. Analytic perturbation solutions to the Venusian orbiter due to the nonspherical gravitational potential

    Institute of Scientific and Technical Information of China (English)

    刘林; C.K.Shum

    2000-01-01

    The analytic perturbation solutions to the motions of a planetary orbiter given in this paper are effective for0< e< 1, where e is the orbital eccentricity of the orbiter. in the solution, it is as-sumed that the rotation of the central body is slow, and its astronomical background is clear. Examples for such planets in the solar system are Ven黶 and Mercury. The perturbation solution is tested numer-ically on two Venusian orbiters with eccentric orbits, PVO and Magellan, and found to be effective.

  16. Analytic perturbation solutions to the Venusian orbiter due to the nonspherical gravitational potential

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The analytic perturbation solutions to the motions of a planetary orbiter given in this paper are effective for 0<e<1,where e is the orbital eccentricity of the orbiter.In the solution,it is assumed that the rotation of the central body is slow,and its astronomical background is clear.Examples for such planets in the solar system are Venus and Mercury.The perturbation solution is tested numerically on two Venusian orbiters with eccentric orbits,PVO and Magellan,and found to be effective.

  17. On Approximate Analytical Solutions of Nonlinear Vibrations of Inextensible Beams using Parameter-Expansion Method

    DEFF Research Database (Denmark)

    Kimiaeifar, Amin; Lund, Erik; Thomsen, Ole Thybo; Barari, Amin

    2010-01-01

    In this work, an analytical method, which is referred to as Parameter-expansion Method is used to obtain the exact solution for the problem of nonlinear vibrations of an inextensible beam. It is shown that one term in the series expansion is sufficient to obtain a highly accurate solution, which is...... valid for the whole domain of the problem. A comparison of the obtained the numerical solution demonstrates that PEM is effective and convenient for solving such problems. After validation of the obtained results, the system response and stability are also discussed....

  18. A New Homotopy Analysis Method for Approximating the Analytic Solution of KdV Equation

    Directory of Open Access Journals (Sweden)

    Vahid Barati

    2014-01-01

    Full Text Available In this study a new technique of the Homotopy Analysis Method (nHAM is applied to obtain an approximate analytic solution of the well-known Korteweg-de Vries (KdV equation. This method removes the extra terms and decreases the time taken in the original HAM by converting the KdV equation to a system of first order differential equations. The resulted nHAM solution at third order approximation is then compared with that of the exact soliton solution of the KdV equation and found to be in excellent agreement.

  19. A class of blowup and global analytical solutions of the viscoelastic Burgers' equations

    Energy Technology Data Exchange (ETDEWEB)

    An, Hongli, E-mail: hongli.an@connect.polyu.hk [College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Cheung, Ka-Luen, E-mail: kaluen@ied.edu.hk [Department of Mathematics and Information Technology, The Hong Kong Institute of Education, 10 Po Ling Road, Tai Po, New Territories (Hong Kong); Yuen, Manwai, E-mail: nevetsyuen@hotmail.com [Department of Mathematics and Information Technology, The Hong Kong Institute of Education, 10 Po Ling Road, Tai Po, New Territories (Hong Kong)

    2013-11-08

    In this Letter, by employing the perturbational method, we obtain a class of analytical self-similar solutions of the viscoelastic Burgers' equations. These solutions are of polynomial-type whose forms, remarkably, coincide with that given by Yuen for the other physical models, such as the compressible Euler or Navier–Stokes equations and two-component Camassa–Holm equations. Furthermore, we classify the initial conditions into several groups and then discuss the properties on blowup and global existence of the corresponding solutions, which may be readily seen from the phase diagram.

  20. Analytic Approximate Solutions for Unsteady Two-Dimensional and Axisymmetric Squeezing Flows between Parallel Plates

    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.

  1. Trigonometric and hyperbolic functions method for constructing analytic solutions to nonlinear plane magnetohydrodynamics equilibrium equations

    Energy Technology Data Exchange (ETDEWEB)

    Moawad, S. M., E-mail: smmoawad@hotmail.com [Department of Mathematics, Faculty of Science, Beni-Suef University, Beni-Suef (Egypt)

    2015-02-15

    In this paper, we present a solution method for constructing exact analytic solutions to magnetohydrodynamics (MHD) equations. The method is constructed via all the trigonometric and hyperbolic functions. The method is applied to MHD equilibria with mass flow. Applications to a solar system concerned with the properties of coronal mass ejections that affect the heliosphere are presented. Some examples of the constructed solutions which describe magnetic structures of solar eruptions are investigated. Moreover, the constructed method can be applied to a variety classes of elliptic partial differential equations which arise in plasma physics.

  2. Trigonometric and hyperbolic functions method for constructing analytic solutions to nonlinear plane magnetohydrodynamics equilibrium equations

    Science.gov (United States)

    Moawad, S. M.

    2015-02-01

    In this paper, we present a solution method for constructing exact analytic solutions to magnetohydrodynamics (MHD) equations. The method is constructed via all the trigonometric and hyperbolic functions. The method is applied to MHD equilibria with mass flow. Applications to a solar system concerned with the properties of coronal mass ejections that affect the heliosphere are presented. Some examples of the constructed solutions which describe magnetic structures of solar eruptions are investigated. Moreover, the constructed method can be applied to a variety classes of elliptic partial differential equations which arise in plasma physics.

  3. Trigonometric and hyperbolic functions method for constructing analytic solutions to nonlinear plane magnetohydrodynamics equilibrium equations

    International Nuclear Information System (INIS)

    In this paper, we present a solution method for constructing exact analytic solutions to magnetohydrodynamics (MHD) equations. The method is constructed via all the trigonometric and hyperbolic functions. The method is applied to MHD equilibria with mass flow. Applications to a solar system concerned with the properties of coronal mass ejections that affect the heliosphere are presented. Some examples of the constructed solutions which describe magnetic structures of solar eruptions are investigated. Moreover, the constructed method can be applied to a variety classes of elliptic partial differential equations which arise in plasma physics

  4. Approximate analytical solution of diffusion equation with fractional time derivative using optimal homotopy analysis method

    Directory of Open Access Journals (Sweden)

    S. Das

    2013-12-01

    Full Text Available In this article, optimal homotopy-analysis method is used to obtain approximate analytic solution of the time-fractional diffusion equation with a given initial condition. The fractional derivatives are considered in the Caputo sense. Unlike usual Homotopy analysis method, this method contains at the most three convergence control parameters which describe the faster convergence of the solution. Effects of parameters on the convergence of the approximate series solution by minimizing the averaged residual error with the proper choices of parameters are calculated numerically and presented through graphs and tables for different particular cases.

  5. Laplace transform solution for heat transfer in composite walls with periodic boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zedan, M.F.; Mujahid, A.M. (King Saud Univ., Riyadh (Saudi Arabia))

    1993-02-01

    An analytic solution was developed for the heat transfer in a composite wall with periodic ambient temperature on one side and a constant-temperature fluid on the other side. A number of test cases with exact solutions showed that the method is accurate in predicting the transient and the steady periodic parts of the response. Computationally, the method is very efficient in the sense that the solution is only obtained at the points(s) of interest and not at all grid points as in finite difference methods. 5 refs., 3 figs.

  6. An analytical solution for an external source problem with delayed neutrons using the telegraphers equation

    International Nuclear Information System (INIS)

    Different current and planned experiments are designed to study the zero power neutron physical behavior of accelerator driven systems (ADS). However, the analysis of these experiments is mostly based on point kinetics. To improve this situation and to overcome the limitations resulting from the separation of space and time, the paper presents a fully analytical approximation solution for a space-time dependent neutron transport problem in a one dimensional system consisting of a homogenized medium with a central neutron source. The basic solution without delayed neutrons is derived with Green's functions without separation of space and time. The delayed neutron production is later on implemented by means of the multiple scale expansion method. This way of separating the different time scales avoids the stiff problem arising in a closed form solution. Finally, a fully analytic approximation solution is generated for the switch on of a localized external neutron source in the center of the homogenized subcritical system. Space time dependent results based on a cross section set for a light water reactor configuration are presented to demonstrate the potential of the developed analytical approximation solution. The development is the first step towards improving the methods for the analysis of kinetic ADS experiments. It is the final goal to provide an improved tool for on site analysis of kinetics ADS experiments. (authors)

  7. The application of the quasistationary derivatives method for calculating analytical solutions of spatial kinetics problems

    International Nuclear Information System (INIS)

    The quasistationary derivatives method is applied in the paper to improve efficiency of numerical algorithms used for calculating analytical solutions of spatial kinetics problems. A one-dimensional problem (BSS-6) published in the ANL Benchmark Problem Book is considered. According to the approach used by the authors of BSS-6, the system of reactor kinetics equations is presented by a system of ordinary differential equations (ODE) obtained after approximation of the diffusion operator by a finite-difference scheme, thus the analytical solution is calculated on the basis of the solution of the full eigenvalue problem. The difficulty is that the matrix of this stiff system is ill-conditioned, therefore standard subroutines for solving problems of linear algebra appear to be unstable numerically here because of the round-off error. The quasistationary derivatives method is used as a preconditioning procedure to diminish the condition number of the system matrix. (author)

  8. Analytical Solutions of a Fractional Diffusion-advection Equation for Solar Cosmic-Ray Transport

    Science.gov (United States)

    Litvinenko, Yuri E.; Effenberger, Frederic

    2014-12-01

    Motivated by recent applications of superdiffusive transport models to shock-accelerated particle distributions in the heliosphere, we analytically solve a one-dimensional fractional diffusion-advection equation for the particle density. We derive an exact Fourier transform solution, simplify it in a weak diffusion approximation, and compare the new solution with previously available analytical results and with a semi-numerical solution based on a Fourier series expansion. We apply the results to the problem of describing the transport of energetic particles, accelerated at a traveling heliospheric shock. Our analysis shows that significant errors may result from assuming an infinite initial distance between the shock and the observer. We argue that the shock travel time should be a parameter of a realistic superdiffusive transport model.

  9. Analytical solutions of a fractional diffusion-advection equation for solar cosmic-ray transport

    CERN Document Server

    Litvinenko, Yuri E

    2014-01-01

    Motivated by recent applications of superdiffusive transport models to shock-accelerated particle distributions in the heliosphere, we solve analytically a one-dimensional fractional diffusion-advection equation for the particle density. We derive an exact Fourier transform solution, simplify it in a weak diffusion approximation, and compare the new solution with previously available analytical results and with a semi-numerical solution based on a Fourier series expansion. We apply the results to the problem of describing the transport of energetic particles, accelerated at a traveling heliospheric shock. Our analysis shows that significant errors may result from assuming an infinite initial distance between the shock and the observer. We argue that the shock travel time should be a parameter of a realistic superdiffusive transport model.

  10. Collisionless Boltzmann equation with an external periodic traveling force: Analytical solution and application to molecular optics

    International Nuclear Information System (INIS)

    We present an analytical solution to the collisionless Boltzmann equation for describing the distribution function of molecular ensembles subject to an external periodic traveling force of pulsed optical fields. We apply our solution to study a pulsed standing wave mirror for neutral molecules, recently proposed [P. Ryytty et al., Phys. Rev. Lett. 84, 5074 (2000)]. Using our analytical solution we study the effects of the anharmonicity of optical potential on the reflectivity of the molecular mirror and the corresponding optimal pulse duration. We demonstrate that the reflectivity of the molecular mirror can be significantly improved by optimizing the pulse duration of the external optical fields when taking into account the anharmonicity of molecular motion

  11. Analytical steady-state solutions for water-limited cropping systems using saline irrigation water

    Science.gov (United States)

    Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.

    2014-12-01

    Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess advantages over available alternatives, including: (i) the solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.

  12. Analytical Solutions of a Nonlinear Convection-Diffusion Equation With Polynomial Sources

    Directory of Open Access Journals (Sweden)

    N. A. Kudryashov

    2016-01-01

    Full Text Available Nonlinear convection–diffusion equations are widely used for the description of various processes and phenomena in physics, mechanics and biology. In this work we consider a family of nonlinear ordinary differential equations which is a traveling wave reduction of a nonlinear convection–diffusion equation with a polynomial source. We study a question about integrability of this family of nonlinear ordinary differential equations. We consider both stationary and non–stationary cases of this equation with and without convection. In order to construct general analytical solutions of equations from this family we use an approach based on nonlocal transformations which generalize the Sundman transformations. We show that in the stationary case without convection the general analytical solution of the considered family of equations can be constructed without any constraints on its parameters and can be expressed via the Weierstrass elliptic function. Since in the general case this solution has a cumbersome form we find some correlations on the parameters which allow us to construct the general solution in the explicit form. We show that in the non–stationary case both with and without convection we can find a general analytical solution of the considered equation only imposing some correlation on the parameters. To this aim we use criteria for the integrability of the Lienard equation which have recently been obtained. We find explicit expressions in terms of exponential and elliptic functions for the corresponding analytical solutions.

  13. Existence of countably many positive solutions for nth-order m-point boundary-value problems on time scales

    Directory of Open Access Journals (Sweden)

    Zhiyong Wang

    2008-09-01

    Full Text Available In this paper, we study the existence of positive solutions for the nonlinear nth-order with m-point singular boundary-value problem. By using the fixed point index theory and a new fixed point theorem in cones, the existence of countably many positive solutions for a nonlinear singular boundary value problem are obtained.

  14. On the Existence and Uniqueness of Rv-Generalized Solution for Dirichlet Problem with Singularity on All Boundary

    Directory of Open Access Journals (Sweden)

    V. Rukavishnikov

    2014-01-01

    Full Text Available The existence and uniqueness of the Rv-generalized solution for the first boundary value problem and a second order elliptic equation with coordinated and uncoordinated degeneracy of input data and with strong singularity solution on all boundary of a two-dimensional domain are established.

  15. Positive solutions to boundary-value problems of p-Laplacian fractional differential equations with a parameter in the boundary

    Directory of Open Access Journals (Sweden)

    Zhenlai Han

    2012-11-01

    Full Text Available In this article, we consider the following boundary-value problem of nonlinear fractional differential equation with $p$-Laplacian operator $$displaylines{ D_{0+}^eta(phi_p(D_{0+}^alpha u(t+a(tf(u=0, quad 01$, $phi_p^{-1}=phi_q$, $1/p+1/q=1$, $0leqslantgamma<1$, $0leqslantxileqslant1$, $lambda>0$ is a parameter, $a:(0,1o [0,+infty$ and $f:[0,+inftyo[0,+infty$ are continuous. By the properties of Green function and Schauder fixed point theorem, several existence and nonexistence results for positive solutions, in terms of the parameter $lambda$ are obtained. The uniqueness of positive solution on the parameter $lambda$ is also studied. Some examples are presented to illustrate the main results.

  16. A Boundary Element Solution to the Problem of Interacting AC Fields in Parallel Conductors

    Directory of Open Access Journals (Sweden)

    Einar M. Rønquist

    1984-04-01

    Full Text Available The ac fields in electrically insulated conductors will interact through the surrounding electromagnetic fields. The pertinent field equations reduce to the Helmholtz equation inside each conductor (interior problem, and to the Laplace equation outside the conductors (exterior problem. These equations are transformed to integral equations, with the magnetic vector potential and its normal derivative on the boundaries as unknowns. The integral equations are then approximated by sets of algebraic equations. The interior problem involves only unknowns on the boundary of each conductor, while the exterior problem couples unknowns from several conductors. The interior and the exterior problem are coupled through the field continuity conditions. The full set of equations is solved by standard Gaussian elimination. We also show how the total current and the dissipated power within each conductor can be expressed as boundary integrals. Finally, computational results for a sample problem are compared with a finite difference solution.

  17. Entry guidance with real-time planning of reference based on analytical solutions

    Science.gov (United States)

    Yu, Wenbin; Chen, Wanchun

    2015-05-01

    In this paper, first, we develop new analytical solutions to hypersonic gliding problem. In the derivation of these solutions, we propose an innovative method based on spectral decomposition for solving a special type of linear system with variable coefficients, where the system matrix can be expressed as the product of a scale function and a constant matrix. Next, we design an entry guidance based on these analytical solutions. In the guidance, the downrange analytical expression is used to plan the longitudinal reference profile satisfying the downrange requirement in real time. Two bank reversals are needed to eliminate the crossrange error. The first is planned by the crossrange analytical expression such that the second is at a specified point near the end of the flight. After the first bank reversal is performed, the second is slightly corrected using the trajectory simulation. Because the longitudinal reference profile and bank reversals are planned onboard, the entry guidance can handle various urgent tasks and deal well with large dispersions in the initial conditions, aerodynamic model and atmospheric model.

  18. Acid in perchloroethylene scrubber solutions used in HTGR fuel preparation processes. Analytical chemistry studies

    International Nuclear Information System (INIS)

    Acids and corrosion products in used perchloroethylene scrubber solutions collected from HTGR fuel preparation processes have been analyzed by several analytical methods to determine the source and possible remedy of the corrosion caused by these solutions. Hydrochloric acid was found to be concentrated on the carbon particles suspended in perchloroethylene. Filtration of carbon from the scrubber solutions removed the acid corrosion source in the process equipment. Corrosion products chemisorbed on the carbon particles were identified. Filtered perchloroethylene from used scrubber solutions contained practically no acid. It is recommended that carbon particles be separated from the scrubber solutions immediately after the scrubbing process to remove the source of acid and that an inhibitor be used to prevent the hydrolysis of perchloroethylene and the formation of acids

  19. Over-reflection of slow magnetosonic waves by homogeneous shear flow: Analytical solution

    International Nuclear Information System (INIS)

    We have analyzed the amplification of slow magnetosonic (or pseudo-Alfvenic) waves (SMW) in incompressible shear flow. As found here, the amplification depends on the component of the wave-vector perpendicular to the direction of the shear flow. Earlier numerical results are consistent with the general analytic solution for the linearized magnetohydrodynamic equations, derived here for the model case of pure homogeneous shear (without Coriolis force). An asymptotically exact analytical formula for the amplification coefficient is derived for the case when the amplification is sufficiently large.

  20. Analytical solutions of the dielectrophoretic and travelling wave forces generated by interdigitated electrode arrays

    International Nuclear Information System (INIS)

    In AC electrokinetics, the application of an AC electric field to a suspension of particles results in the manipulation and separation of the particles also the movement of the fluid. One application is dielectrophoresis (DEP). The second effect is travelling wave dielectrophoresis (twDEP). This paper presents the analytical solutions of the dielectrophoretic and travelling wave forces for the interdigitated electrode arrays energised with either a two- or four-phase signal, respectively. The torque that rotates the particle in the four-phase travelling wave arrays is also analytically solved.