Numberical Solution to Transient Heat Flow Problems
ERIC Educational Resources Information Center
Kobiske, Ronald A.; Hock, Jeffrey L.
1973-01-01
Discusses the reduction of the one- and three-dimensional diffusion equation to the difference equation and its stability, convergence, and heat-flow applications under different boundary conditions. Indicates the usefulness of this presentation for beginning students of physics and engineering as well as college teachers. (CC)
Solution to problems of bacterial impurity of heating systems
NASA Astrophysics Data System (ADS)
Sharapov, V. I.; Zamaleev, M. M.
2015-09-01
The article describes the problems of the operation of open and closed district heating systems related to the bacteriological contamination of heating-system water. It is noted that district heating systems are basically safe in sanitary epidemiological terms. Data on the dangers of sulfide contamination of heating systems are given. It is shown that the main causes of the development of sulfate-reducing and iron bacteria in heating systems are a significant biological contamination of source water to fuel heating systems, which is determined by water oxidizability, and a low velocity of the motion of heating-system water in the heating system elements. A case of sulfide contamination of a part of the outdoor heat-supply system of the city of Ulyanovsk is considered in detail. Measures for cleaning pipelines and heating system equipment from the waste products of sulfate-reducing bacteria and iron bacteria and for improving the quality of heating-system water by organizing the hydraulic and water-chemistry condition that makes it possible to avoid the bacteriological contamination of heating systems are proposed. The positive effect of sodium silicate on the prevention of sulfide contamination of heating systems is shown.
Numerical Solution of an Ill-Posed Problem Arising in Wind Tunnel Heat Transfer Data Reduction,
1981-12-04
Solutions of Ill - Posed Problems , A. H. Winston and Sons, 1977 . 6. Widder, D. V., The Heat Equation, Academic Press. 7. Richtmyer, R. D. and...DEC Al J B BELL. A B WAROLAW UNCLASSI ESWC WC/TR2l3lSBI.ADF5 046NL U" ~ a5 11111.5 N NSWC TR 82-32 cNUMERICAL SOLUTION OF AN ILL - POSED PROBLEM ...is ill - posed . A Tikhonov regularization procedure5 is then used to compute stable approximate solutions to the integral equation. In the
Solution of inverse heat conduction problem using the Tikhonov regularization method
NASA Astrophysics Data System (ADS)
Duda, Piotr
2017-02-01
It is hard to solve ill-posed problems, as calculated temperatures are very sensitive to errors made while calculating "measured" temperatures or performing real-time measurements. The errors can create temperature oscillation, which can be the cause of an unstable solution. In order to overcome such difficulties, a variety of techniques have been proposed in literature, including regularization, future time steps and smoothing digital filters. In this paper, the Tikhonov regularization is applied to stabilize the solution of the inverse heat conduction problem. The impact on the inverse solution stability and accuracy is demonstrated.
ERIC Educational Resources Information Center
Connors, G. Patrick
Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…
ERIC Educational Resources Information Center
Connors, G. Patrick
Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…
Numerical solution of fluid flow and heat tranfer problems with surface radiation
NASA Technical Reports Server (NTRS)
Ahuja, S.; Bhatia, K.
1995-01-01
This paper presents a numerical scheme, based on the finite element method, to solve strongly coupled fluid flow and heat transfer problems. The surface radiation effect for gray, diffuse and isothermal surfaces is considered. A procedure for obtaining the view factors between the radiating surfaces is discussed. The overall solution strategy is verified by comparing the available results with those obtained using this approach. An analysis of a thermosyphon is undertaken and the effect of considering the surface radiation is clearly explained.
Evaluation of a transfinite element numerical solution method for nonlinear heat transfer problems
NASA Technical Reports Server (NTRS)
Cerro, J. A.; Scotti, S. J.
1991-01-01
Laplace transform techniques have been widely used to solve linear, transient field problems. A transform-based algorithm enables calculation of the response at selected times of interest without the need for stepping in time as required by conventional time integration schemes. The elimination of time stepping can substantially reduce computer time when transform techniques are implemented in a numerical finite element program. The coupling of transform techniques with spatial discretization techniques such as the finite element method has resulted in what are known as transfinite element methods. Recently attempts have been made to extend the transfinite element method to solve nonlinear, transient field problems. This paper examines the theoretical basis and numerical implementation of one such algorithm, applied to nonlinear heat transfer problems. The problem is linearized and solved by requiring a numerical iteration at selected times of interest. While shown to be acceptable for weakly nonlinear problems, this algorithm is ineffective as a general nonlinear solution method.
Evaluation of a transfinite element numerical solution method for nonlinear heat transfer problems
NASA Astrophysics Data System (ADS)
Cerro, J. A.; Scotti, S. J.
1991-07-01
Laplace transform techniques have been widely used to solve linear, transient field problems. A transform-based algorithm enables calculation of the response at selected times of interest without the need for stepping in time as required by conventional time integration schemes. The elimination of time stepping can substantially reduce computer time when transform techniques are implemented in a numerical finite element program. The coupling of transform techniques with spatial discretization techniques such as the finite element method has resulted in what are known as transfinite element methods. Recently attempts have been made to extend the transfinite element method to solve nonlinear, transient field problems. This paper examines the theoretical basis and numerical implementation of one such algorithm, applied to nonlinear heat transfer problems. The problem is linearized and solved by requiring a numerical iteration at selected times of interest. While shown to be acceptable for weakly nonlinear problems, this algorithm is ineffective as a general nonlinear solution method.
NASA Astrophysics Data System (ADS)
Mehta, R. C.; Jayachandran, T.
1987-06-01
A numerical solution of the nonlinear inverse heat conduction problem is obtained using an in-line method in conjunction with the measured thermocouple temperature history. The deforming finite elements technique is used to treat initial time delay in temperature response due to thermocouple location. In the absence of elements deformation, the method reduces to the conventional Galerkin formulation. A three-time level implicit scheme, which is unconditionally stable and convergent, is employed for the numerical solution. The temperature-dependent thermophysical properties in the matrices are evaluated at the intermediate level. The complication of solving a set of nonlinear algebraic equations at each step is avoided. Illustration of the technique is made on the one-dimensional problem with a thermal radiation boundary condition. The results demonstrate that the method is remarkable in its ability to predict surface condition without debilitation.
Conduction heat transfer solutions
VanSant, James H.
1980-03-01
This text is a collection of solutions to a variety of heat conduction problems found in numerous publications, such as textbooks, handbooks, journals, reports, etc. Its purpose is to assemble these solutions into one source that can facilitate the search for a particular problem solution. Generally, it is intended to be a handbook on the subject of heat conduction. This material is useful for engineers, scientists, technologists, and designers of all disciplines, particularly those who design thermal systems or estimate temperatures and heat transfer rates in structures. More than 500 problem solutions and relevant data are tabulated for easy retrieval. There are twelve sections of solutions which correspond with the class of problems found in each. Geometry, state, boundary conditions, and other categories are used to classify the problems. A case number is assigned to each problem for cross-referencing, and also for future reference. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. At least one source reference is given so that the user can review the methods used to derive the solutions. Problem solutions are given in the form of equations, graphs, and tables of data, all of which are also identified by problem case numbers and source references.
NASA Astrophysics Data System (ADS)
Yan, Yan; Keyes, David E.
2015-01-01
We study a new optimization scheme that generates smooth and robust solutions for Dirichlet velocity boundary control (DVBC) of conjugate heat transfer (CHT) processes. The solutions to the DVBC of the incompressible Navier-Stokes equations are typically nonsmooth, due to the regularity degradation of the boundary stress in the adjoint Navier-Stokes equations. This nonsmoothness is inherited by the solutions to the DVBC of CHT processes, since the CHT process couples the Navier-Stokes equations of fluid motion with the convection-diffusion equations of fluid-solid thermal interaction. Our objective in the CHT boundary control problem is to select optimally the fluid inflow profile that minimizes an objective function that involves the sum of the mismatch between the temperature distribution in the fluid system and a prescribed temperature profile and the cost of the control. Our strategy to resolve the nonsmoothness of the boundary control solution is based on two features, namely, the objective function with a regularization term on the gradient of the control profile on both the continuous and the discrete levels, and the optimization scheme with either explicit or implicit smoothing effects, such as the smoothed Steepest Descent and the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) methods. Our strategy to achieve the robustness of the solution process is based on combining the smoothed optimization scheme with the numerical continuation technique on the regularization parameters in the objective function. In the section of numerical studies, we present two suites of experiments. In the first one, we demonstrate the feasibility and effectiveness of our numerical schemes in recovering the boundary control profile of the standard case of a Poiseuille flow. In the second one, we illustrate the robustness of our optimization schemes via solving more challenging DVBC problems for both the channel flow and the flow past a square cylinder, which use initial
Conduction heat transfer solutions
VanSant, J.H.
1983-08-01
This text is a collection of solutions to a variety of heat conduction problems found in numerous publications, such as textbooks, handbooks, journals, reports, etc. Its purpose is to assemble these solutions into one source that can facilitate the search for a particular problem solution. Generally, it is intended to be a handbook on the subject of heat conduction. There are twelve sections of solutions which correspond with the class of problems found in each. Geometry, state, boundary conditions, and other categories are used to classify the problems. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. The introduction presents a synopsis on the theory, differential equations, and boundary conditions for conduction heat transfer. Some discussion is given on the use and interpretation of solutions. Supplementary data such as mathematical functions, convection correlations, and thermal properties are included for aiding the user in computing numerical values from the solutions. 155 figs., 92 refs., 9 tabs.
NASA Astrophysics Data System (ADS)
Zmywaczyk, J.; Koniorczyk, P.
2009-08-01
The problem of simultaneous identification of the thermal conductivity Λ(T) and the asymmetry parameter g of the Henyey-Greenstein scattering phase function is under consideration. A one-dimensional configuration in a grey participating medium with respect to silica fibers for which the thermophysical and optical properties are known from the literature is accepted. To find the unknown parameters, it is assumed that the thermal conductivity Λ(T) may be represented in a base of functions {1, T, T 2, . . .,T K } so the inverse problem can be applied to determine a set of coefficients {Λ0, Λ1, . . ., Λ K ; g}. The solution of the inverse problem is based on minimization of the ordinary squared differences between the measured and model temperatures. The measured temperatures are considered known. Temperature responses measured or theoretically generated at several different distances from the heat source along an x axis of the specimen set are known as a result of the numerical solution of the transient coupled heat transfer in a grey participating medium. An implicit finite volume method (FVM) is used for handling the energy equation, while a finite difference method (FDM) is applied to find the sensitivity coefficients with respect to the unknown set of coefficients. There are free parameters in a model, so these parameters are changed during an iteration process used by the fitting procedure. The Levenberg- Marquardt fitting procedure is iteratively searching for best fit of these parameters. The source term in the governing conservation-of-energy equation taking into account absorption, emission, and scattering of radiation is calculated by means of a discrete ordinate method together with an FDM while the scattering phase function approximated by the Henyey-Greenstein function is expanded in a series of Legendre polynomials with coefficients {c l } = (2l + 1)g l . The numerical procedure proposed here also allows consideration of some cases of coupled heat
Exact analytical solution to a transient conjugate heat-transfer problem
NASA Technical Reports Server (NTRS)
Sucec, J.
1973-01-01
An exact analytical solution is found for laminar, constant-property, slug flow over a thin plate which is also convectively cooled from below. The solution is found by means of two successive Laplace transformations when a transient in the plate and the fluid is initiated by a step change in the fluid inlet temperature. The exact solution yields the transient fluid temperature, surface heat flux, and surface temperature distributions. The results of the exact transient solution for the surface heat flux are compared to the quasi-steady values, and a criterion for the validity of the quasi-steady results is found. Also the effect of the plate coupling parameter on the surface heat flux are investigated.
NASA Astrophysics Data System (ADS)
Maciejewska, Beata; Piasecka, Magdalena
This paper shows the results concerning flow boiling heat transfer in an asymmetrically heated vertical minichannel. The heated element for FC-72 Fluorinert flowing in that minichannel was a thin foil. The foil surface temperature was monitored continuously at 18 points by K-type thermocouples from the outer foil surface. Fluid temperature and pressure in the minichannel inlet and outlet, current supplied to the foil and voltage drop were also monitored. Measurements were carried out at 1 s intervals. The objective was to determine the heat transfer coefficient on the heated foil-fluid contact surface in the minichannel. It was obtained from the Robin boundary condition. The foil temperature was the result of solving the nonstationary two-dimensional inverse boundary problem in the heated foil. Using the FEM combined with Trefftz functions as basis functions solved the problem. The unknown temperature values at nodes were calculated by minimising the adequate functional. The values of local heat transfer coefficients were consistent with the results obtained by the authors in their previous studies when steady-state conditions were analysed. This time, however, these values were analysed as time dependent, which facilitated observation of coefficient changes that were impossible to observe under the steady-state conditions.
NASA Astrophysics Data System (ADS)
Denisov, A. M.
2016-10-01
An initial-boundary value problem for the two-dimensional heat equation with a source is considered. The source is the sum of two unknown functions of spatial variables multiplied by exponentially decaying functions of time. The inverse problem is stated of determining two unknown functions of spatial variables from additional information on the solution of the initial-boundary value problem, which is a function of time and one of the spatial variables. It is shown that, in the general case, this inverse problem has an infinite set of solutions. It is proved that the solution of the inverse problem is unique in the class of sufficiently smooth compactly supported functions such that the supports of the unknown functions do not intersect. This result is extended to the case of a source involving an arbitrary finite number of unknown functions of spatial variables multiplied by exponentially decaying functions of time.
NASA Astrophysics Data System (ADS)
Shivanian, Elyas; Hosseini Ghoncheh, S. J.
2017-02-01
In this paper, the nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient is revisited. In this problem, it has been assumed that the heat transfer coefficient is expressed in a power-law form and the thermal conductivity is a linear function of temperature. A method based on the traditional shooting method and the homotopy analysis method is applied, the so-called shooting homotopy analysis method (SHHAM), to the governing nonlinear differential equation. In this technique, more high-order approximate solutions are computable and multiple solutions are easily searched and discovered due to being free of the symbolic variable. It is found that the solution might be empty, unique or dual depending on the values of the parameters of the model. Furthermore, corresponding fin efficiencies with high accuracy are computed. As a consequence, a new branch solution for this nonlinear problem by a new proposed method, based on the traditional shooting method and the homotopy analysis method, is obtained.
Inverse heat conduction problems
NASA Astrophysics Data System (ADS)
Orlande, Helcio Rangel Barreto
We present the solution of the following inverse problems: (1) Inverse Problem of Estimating Interface Conductance Between Periodically Contacting Surfaces; (2) Inverse Problem of Estimating Interface Conductance During Solidification via Conjugate Gradient Method; (3) Determination of the Reaction Function in a Reaction-Diffusion Parabolic Problem; and (4) Simultaneous Estimation of Thermal Diffusivity and Relaxation Time with Hyperbolic Heat Conduction Model. Also, we present the solution of a direct problem entitled: Transient Thermal Constriction Resistance in a Finite Heat Flux Tube. The Conjugate Gradient Method with Adjoint Equation was used in chapters 1-3. The more general function estimation approach was treated in these chapters. In chapter 1, we solve the inverse problem of estimating the timewise variation of the interface conductance between periodically contacting solids, under quasi-steady-state conditions. The present method is found to be more accurate than the B-Spline approach for situations involving small periods, which are the most difficult on which to perform the inverse analysis. In chapter 2, we estimate the timewise variation of the interface conductance between casting and mold during the solidification of aluminum. The experimental apparatus used in this study is described. In chapter 3, we present the estimation of the reaction function in a one dimensional parabolic problem. A comparison of the present function estimation approach with the parameter estimation technique, wing B-Splines to approximate the reaction function, revealed that the use of function estimation reduces the computer time requirements. In chapter 4 we present a finite difference solution for the transient constriction resistance in a cylinder of finite length with a circular contact surface. A numerical grid generation scheme was used to concentrate grid points in the regions of high temperature gradients in order to reduce discretization errors. In chapter 6, we
NASA Astrophysics Data System (ADS)
Bocharov, A. N.; Bityurin, V. A.; Golovin, N. N.; Evstigneev, N. M.; Petrovskiy, V. P.; Ryabkov, O. I.; Teplyakov, I. O.; Shustov, A. A.; Solomonov, Yu S.; Fortov, V. E.
2016-11-01
In this paper, an approach to solve conjugate heat- and mass-transfer problems is considered to be applied to hypersonic vehicle surface of arbitrary shape. The approach under developing should satisfy the following demands. (i) The surface of the body of interest may have arbitrary geometrical shape. (ii) The shape of the body can change during calculation. (iii) The flight characteristics may vary in a wide range, specifically flight altitude, free-stream Mach number, angle-of-attack, etc. (iv) The approach should be realized with using the high-performance-computing (HPC) technologies. The approach is based on coupled solution of 3D unsteady hypersonic flow equations and 3D unsteady heat conductance problem for the thick wall. Iterative process is applied to account for ablation of wall material and, consequently, mass injection from the surface and changes in the surface shape. While iterations, unstructured computational grids both in the flow region and within the wall interior are adapted to the current geometry and flow conditions. The flow computations are done on HPC platform and are most time-consuming part of the whole problem, while heat conductance problem can be solved on many kinds of computers.
NASA Technical Reports Server (NTRS)
Kozdoba, L. A.; Krivoshei, F. A.
1985-01-01
The solution of the inverse problem of nonsteady heat conduction is discussed, based on finding the coefficient of the heat conduction and the coefficient of specific volumetric heat capacity. These findings are included in the equation used for the electrical model of this phenomenon.
NASA Astrophysics Data System (ADS)
Svetushkov, N. N.
2016-11-01
The paper deals with a numerical algorithm to reduce the overall system of integral equations describing the heat transfer process at any geometrically complex area (both twodimensional and three-dimensional), to the iterative solution of a system of independent onedimensional integral equations. This approach has been called "string method" and has been used to solve a number of applications, including the problem of the detonation wave front for the calculation of heat loads in pulse detonation engines. In this approach "the strings" are a set of limited segments parallel to the coordinate axes, into which the whole solving area is divided (similar to the way the strings are arranged in a tennis racket). Unlike other grid methods where often for finding solutions, the values of the desired function in the region located around a specific central point here in each iteration step is determined by the solution throughout the length of the one-dimensional "string", which connects the two end points and set them values and determine the temperature distribution along all the strings in the first step of an iterative procedure.
NASA Astrophysics Data System (ADS)
Mezouar, M.; Garbarino, G.; Svitlik, V.; Dewaele, A.
2016-12-01
The laser-heated diamond anvil cell (DAC) is the only static technique that can create extreme temperatures at extreme pressures (P>200 GPa). Temperatures in excess of 5000K can be achieved for samples under pressure in diamond cells by heating with high-power infrared lasers. Because of their low absorption by the diamond anvils, hard X-rays are ideal for probing micro-samples subjected to such extreme conditions. The array of X-ray techniques that was initially restricted to structural measurements using X-Ray diffraction is now extended to include several others such as inelastic X-ray Scattering, Mossbauer spectroscopy and EXAFS. As a direct consequence, many scientific breakthroughs have been achieved across fields ranging from Earth and planetary sciences to fundamental physics, chemistry and materials science. However, despite these important technical and scientific achievements, this kind of experiments still remains very challenging. The difficulties originate from multiple factors including undesired chemical reactions, inaccurate high P-T metrology, and uncertainty in the relative alignment of X-ray and laser beams. In melting studies using X-rays, additional problems can occur such as the use of an unambiguous melting criterion. In this presentation, these problems will be discussed and possible solutions proposed.
NASA Astrophysics Data System (ADS)
Edwards, C. F.; Hahn, D. W.
Our interest in spray cooling stems from a problem in high-temperature materials synthesis. Specifically, it is the growth of diamond films by flame chemical vapor deposition (CVD). A high velocity jet of premixed C2H2/O2/H2 is formed into a stagnation point flow over the surface of a molybdenum mandrel causing the formation of a highly strained flame immediately adjacent to the surface. The difficulty that arises is that concomitant with the flux of energetic species to the surface is a large flux of heat which must be removed from the mandrel if control of the growth process is to be maintained. The situation is further complicated by the fact that the deposition surface temperature must be held to a tight tolerance somewhere within the optimal diamond growth range (approximately 1200 K) and the heat extraction must be made in a one-dimensional fashion to preserve the uniform boundary condition on the flame. Since the cooling surface temperature is fixed near the saturation condition by the phase change of the droplets, and the heat flux into the mandrel is imposed by the flame, the only way to achieve a desired deposition surface temperature is to vary the thermal resistance of the mandrel itself. Since the cooling surface is isothermal, uniform temperature at the deposition surface will only result if the heat flux through the mandrel is uniform, that is, if the sides of the mandrel are effectively adiabatic and the flame is uniform over the mandrel surface. If either of these conditions is not met, the deposition surface temperature cannot be made uniform using this method. These limitations could be overcome if it were possible to carry out the spray cooling process without being tied to the isothermal boundary condition inherent in phase-cooling. Such a solution exists for spray cooling above the Leidenfrost temperature; that is the subject of this paper -- super-Leidenfrost spray cooling.
ERIC Educational Resources Information Center
NatureScope, 1989
1989-01-01
Examines some of the reasons tropical rain forests are being destroyed and ways people are working to protect these forests. Provides activities on how people can help, reason for saving the forests, individual actions related to forest problems and solutions, and issues and problems. Three copyable pages accompany activities. (Author/RT)
NASA Astrophysics Data System (ADS)
Egidi, Nadaniela; Giacomini, Josephin; Maponi, Pierluigi
2016-06-01
Matter of this paper is the study of the flow and the corresponding heat transfer in a U-shaped heat exchanger. We propose a mathematical model that is formulated as a forced convection problem for incompressible and Newtonian fluids and results in the unsteady Navier-Stokes problem. In order to get a solution, we discretise the equations with both the Finite Elements Method and the Finite Volumes Method. These procedures give rise to a non-symmetric indefinite quadratic system of equations. Thus, three regularisation techniques are proposed to make approximations effective and ideas to compare their results are provided.
Tsai, Y.M.; Crane, R.A. )
1992-05-01
Heat transfer across surfaces in imperfect contact occurs in many practical situations. Since the thermal contact conductance problem has appeared in the literature, substantial efforts have been made to estimate the thermal conductance across the interface. Some of the techniques recently developed of estimating thermal contact conductance are based on experimental temperature data at one or several interior positions of the contacting solids and the calculation of the temperature at these locations for known contact conductance. Consequently, an accurate and efficient method for computing temperature distributions because quite important. FDM and FEM are most widely used. However, for most contact conductance computation methods, only the temperatures at the contacting regions and several other positions near the interface need to be determined, so the general FDM and FEM are not particularly efficient in solving this problem. This paper presents an analytical temperature distribution solution to the one-dimensional symmetric system with heat flux on one outside surface and insulation on the other. This analysis provides a theoretical basis for transient measurement of thermal contact conductance. While it is common practice in steady-state measurements to use a water-cooled heat sink, it is possible to limit the transient solution to time interval prior to any detectable temperature increase at the cold end. This effectively eliminates the need for water cooling and permits the use of an insulated boundary. The analytical solution to the mentioned problem obtained shows that for a symmetric system the temperature distribution solution includes two sets of distinct eigenfunctions.
1988-12-01
direction of heat flow [Ref. 1:p. 4]. 7 3. Rate Equations The three principle modes of heat transfer are conduction , convection , and radiation. The rate of...8217) C READ IN MATRIX SIZE READ (14,*) NODES,NPHI,NLAYER C WRITE HEADERS TO DATA FILE 15 (ERROR) WRITE (15,*) ’EXPLICIT - WITH CONDUCTION , CONVECTION AND... CONDUCTION , CONVECTION AND RADIATION 1’ WRITE (15,*) WRITE (15,*) ’DATA SAVED AS FILE:’ WRITE (15,*) WRITE (15,*) ’CPU TIME:’ WRITE (15,*) WRITE (lI
Fuelwood Problems and Solutions
D. Evan Mercer; John Soussan
1992-01-01
Concern over the "fuelwood crisis" facing the world's poor has been widespread since the late 1970s (Eckholm et al. 1984; Soussan 1988; Agarwal 1986). At first the problem was frequently overstated. In the extreme, analysts (foresters, economists, and others) in many countries made erroneous projections of the rapid total destruction of the biomass...
Yamazaki, K; Mori, T; Tomioka, J; Litwak, P; Antaki, J F; Tagusari, O; Koyanagi, H; Griffith, B P; Kormos, R L
1997-01-01
offers a practical solution to the shaft seal problem and heat related complications, which currently limit the use of implantable rotary blood pumps.
NASA Astrophysics Data System (ADS)
Yankovskii, A. P.
2017-03-01
The nonlinear problem of non-stationary heat conductivity of the layered anisotropic heat-sensitive shells was formulated taking into account the linear dependence of thermal-physical characteristics of the materials of phase compositions on the temperature. The initial-boundary-value problem is formulated in the dimensionless form, and four small parameters are identified: thermal-physical, characterizing the degree of heat sensitivity of the layer material; geometric, characterizing the relative thickness of the thin-walled structure, and two small Biot numbers on the front surfaces of shells. A sequential recursion of dimensionless equations is carried out, at first, using the thermalphysical small parameter, then, small Biot numbers and, finally, geometrical small parameter. The first type of recursion allowed us to linearize the problem of heat conductivity, and on the basis of two latter types of recursion, the outer asymptotic expansion of solution to the problem of non-stationary heat conductivity of the layered anisotropic non-uniform shells and plates under boundary conditions of the II and III kind and small Biot numbers on the facial surfaces was built, taking into account heat sensitivity of the layer materials. The resulting two-dimensional boundary problems were analyzed, and asymptotic properties of solutions to the heat conductivity problem were studied. The physical explanation was given to some aspects of asymptotic temperature decomposition.
Methods and problems in heat and mass transfer
NASA Astrophysics Data System (ADS)
Kotliar, Iakov Mikhailovich; Sovershennyi, Viacheslav Dmitrievich; Strizhenov, Dmitrii Sergeevich
The book focuses on the mathematical methods used in heat and mass transfer problems. The theory, statement, and solution of some problems of practical importance in heat and mass transfer are presented, and methods are proposed for solving algebraic, transcendental, and differential equations. Examples of exact solutions to heat and mass transfer equations are given. The discussion also covers some aspects of the development of a mathematical model of turbulent flows.
Inverse problem solution in ellipsometry
NASA Astrophysics Data System (ADS)
Zabashta, Lubov A.; Zabashta, Oleg I.
1995-11-01
Interactive graphic system 'ELLA' is described which is an integrated program packet for reverse problem solution in ellipsometry. The solutions stable to experimental errors are found by two algorithms: a simplex method under constraints and a regularizing iteration method. A developed graphic procedure kit includes display of graphic surface layers, their optical parameters, and all main results of intermediate calculations. Specialized graphic input functions allow us to change the parameters of a chosen solution method, the basic data, to enter new additional information, etc. On the examples of model structure of GaAs-oxide MAI capabilities in ellipsometry for determination of multilayer structure optical parameters are studied.
New computer program solves wide variety of heat flow problems
NASA Technical Reports Server (NTRS)
Almond, J. C.
1966-01-01
Boeing Engineering Thermal Analyzer /BETA/ computer program uses numerical methods to provide accurate heat transfer solutions to a wide variety of heat flow problems. The program solves steady-state and transient problems in almost any situation that can be represented by a resistance-capacitance network.
Control of heat source in a heat conduction problem
NASA Astrophysics Data System (ADS)
Lyashenko, V.; Kobilskaya, E.
2014-11-01
The mathematical model of thermal processes during the heat treatment of a moving axisymmetric environment, for example wire. is considered. The wire is heated by internal constantly or periodically operating heat source. It is presented in the form of initial-boundary value problem for the unsteady heat equation with internal constantly or periodically operating heat source. The purpose of the work is the definition of control parameter of temperature field of a moving area, which is heated by internal heat source. The control parameters are determined by solving a nonlocal problem for the heat equation. The problem of getting an adequate temperature distribution throughout the heating area is considered. Therefore, a problem of heat source control is solved, in particular, control by electric current. Control of the heat source allows to maintain the necessary, from a technological point of view, temperature in the heating area. In this paper, to find additional information about the source of heat. The integral condition is used in the control problem. Integral condition, which is considered in the work, determines the energy balance of the heating zone and connects the desired temperature distribution in the internal points of area with temperatures at the boundaries. Control quality in an extremum formulation of the problem is assessed using the quadratic functional. In function space, from a physical point of view, proposed functional is the absolute difference between the actual emission of energy and absorbed energy in the heating zone. The absorbed energy is calculated by solving of the boundary value problem. Methods of determining the control parameters of temperature field are proposed. The resulting problem is solved by iterative methods. At different physical conditions, numerical calculations are carried out, control parameters of the heat treatment process are obtained.
NASA Astrophysics Data System (ADS)
Klimeš, Lubomír; Mauder, Tomáš; Charvát, Pavel; Štétina, Josef
2016-09-01
Materials undergoing a phase change have a number of applications in practice and engineering. Computer simulation tools are often used for investigation of such heat transfer problems with phase changes since they are fast and relatively not expensive. However, a crucial issue is the accuracy of these simulation tools. Numerical methods from the interface capturing category are frequently applied. Such approaches, however, allow for only approximate tracking of the interface between the phases. The paper presents an accuracy analysis and comparison of two widely used interface capturing methods—the enthalpy and the effective heat capacity methods—with the front tracking algorithm. A paraffin-based phase change material is assumed in the study. Computational results show that the front tracking algorithm provides a significantly higher accuracy level than the considered interface capturing methods.
Conformally flat solution with heat flux
Banerjee, A.; Dutta Choudhury, S. B.; Bhui, B. K.
1989-07-15
It is shown that the spherically symmetric solution previously given by Maiti is not the most general conformally flat solution for a shear-free and rotation-free fluid with heat flux. We have presented a more general solution for such a distribution and have considered the conditions of fit at the boundary of a simple spherically symmetric model with heat flux across the boundary with the exterior Vaidya metric.
Gelation on heating of supercooled gelatin solutions.
Guigo, Nathanaël; Sbirrazzuoli, Nicolas; Vyazovkin, Sergey
2012-04-23
Diluted (1.0-1.5 wt%) aqueous gelatin solutions have been cooled to -10 °C at a cooling rate 20 °C min(-1) without freezing and detectable gelation. When heated at a constant heating rate (0.5 -2 °C min(-1)), the obtained supercooled solutions demonstrate an atypical process of gelation that has been characterized by regular and stochastically modulated differential scanning calorimetry (DSC) as well as by isoconversional kinetic analysis. The process is detectable as an exothermic peak in the total heat flow of regular DSC and in the nonreversing heat flow of stochastically modulated DSC. Isoconversional kinetic analysis applied to DSC data reveals that the effective activation energy of the process increases from approximately 75 to 200 kJ mol(-1) as a supercooled solution transforms to gel on continuous heating.
Numerical solutions for heat flow in adhesive lap joints
NASA Technical Reports Server (NTRS)
Howell, P. A.; Winfree, William P.
1992-01-01
The present formulation for the modeling of heat transfer in thin, adhesively bonded lap joints precludes difficulties associated with large aspect ratio grids required by standard FEM formulations. This quasi-static formulation also reduces the problem dimensionality (by one), thereby minimizing computational requirements. The solutions obtained are found to be in good agreement with both analytical solutions and solutions from standard FEM programs. The approach is noted to yield a more accurate representation of heat-flux changes between layers due to a disbond.
A flux correction method for the conjugate heat transfer problem
He, M.; Bishop, P.J.; Minardi, A.; Kassab, A.J.
1995-12-31
A computational method, the flux correction method, is proposed to deal with the conjugate heat transfer problem, which uses a coupled FDM/BEM iteration scheme. The convective heat transfer in the fluid is solved using the BEM. The two solutions are coupled by enforcing continuity of temperature and heat flux at the solid-fluid interfaces. The proposed method is tested using available experimental data. For the considered cases of flow in a parallel plate channel subjected to constant heat flux or constant temperature, good agreements are observed.
On the Magnetospheric Heating Problem
NASA Astrophysics Data System (ADS)
Nykyri, K.; Moore, T.; Dimmock, A. P.; Ma, X.; Johnson, J.; Delamere, P. A.
2016-12-01
In the Earth's magnetosphere the specific entropy, increases by approximately two orders of magnitude when transitioning from the magnetosheath into the magnetosphere. However, the origin of this non-adiabatic heating is not well understood. In addition, there exists a dawn-dusk temperature asymmetry in the flanks of the plasma sheet - the cold component ions are hotter by 30-40% at the dawnside plasma sheet compared to the duskside plasma sheet. Our recent statistical study of magnetosheath temperatures using 7 years of THEMIS data indicates that ion magnetosheath temperatures downstream of quasi-parallel (dawn-flank for the Parker-Spiral IMF) bow shock are only 15 percent higher than downstream of the quasi-perpendicular shock. This magnetosheath temperature asymmetry is therefore inadequate to cause the observed level of the plasma sheet temperature asymmetry. In this presentation we address the origin of non-adiabatic heating from the magnetosheath into the plasma sheet by utilizing small Cluster spacecraft separations, 9 years of statistical THEMIS data as well as Hall-MHD and hybrid simulations. We present evidence of a new physical mechanism capable of cross-scale energy transport at the flank magnetopause with strong contributions to the non-adiabatic heating observed between the magnetosheath and plasma sheet. This same heating mechanism may occur and drive asymmetries also in the magnetospheres of gas giants: Jupiter and Saturn, as well as play role elsewhere in the universe where significant flow shears are present such as in the solar corona, and other astrophysical and laboratory plasmas.
Magnetic induced heating of nanoparticle solutions
Murph, S. Hunyadi; Brown, M.; Coopersmith, K.; Fulmer, S.; Sessions, H.; Ali, M.
2016-12-02
Magnetic induced heating of nanoparticles (NP) provides a useful advantage for many energy transfer applications. This study aims to gain an understanding of the key parameters responsible for maximizing the energy transfer leading to nanoparticle heating through the use of simulations and experimental results. It was found that magnetic field strength, NP concentration, NP composition, and coil size can be controlled to generate accurate temperature profiles in NP aqueous solutions.
Solution of Nonlinear Least-Squares Problems.
1987-07-01
Computation Building 460, Room 313 Stanford University Stanford, California 94305-2140 0 87 i4 3 4 SOLUTION OF NONLINEAR LEAST-SQUARES PROBLEMS A...Performance on a Well-Conditioned Zero -Residual Problem ............. 84 4.7 Num erical Results...termination conditions A superscspt o following a problem number indicates a zero -residual problem A superscipt following a problem number denotes a
Contact of boundary-value problems and nonlocal problems in mathematical models of heat transfer
NASA Astrophysics Data System (ADS)
Lyashenko, V.; Kobilskaya, O.
2015-10-01
In this paper the mathematical models in the form of nonlocal problems for the two-dimensional heat equation are considered. Relation of a nonlocal problem and a boundary value problem, which describe the same physical heating process, is investigated. These problems arise in the study of the temperature distribution during annealing of the movable wire and the strip by permanent or periodically operating internal and external heat sources. The first and the second nonlocal problems in the mobile area are considered. Stability and convergence of numerical algorithms for the solution of a nonlocal problem with piecewise monotone functions in the equations and boundary conditions are investigated. Piecewise monotone functions characterize the heat sources and heat transfer conditions at the boundaries of the area that is studied. Numerous experiments are conducted and temperature distributions are plotted under conditions of internal and external heat sources operation. These experiments confirm the effectiveness of attracting non-local terms to describe the thermal processes. Expediency of applying nonlocal problems containing nonlocal conditions - thermal balance conditions - to such models is shown. This allows you to define heat and mass transfer as the parameters of the process control, in particular heat source and concentration of the substance.
Radioactive Waste...The Problem and Some Possible Solutions
ERIC Educational Resources Information Center
Olivier, Jean-Pierre
1977-01-01
Nuclear safety is a highly technical and controversial subject that has caused much heated debate and political concern. This article examines the problems involved in managing radioactive wastes and the techniques now used. Potential solutions are suggested and the need for international cooperation is stressed. (Author/MA)
Radioactive Waste...The Problem and Some Possible Solutions
ERIC Educational Resources Information Center
Olivier, Jean-Pierre
1977-01-01
Nuclear safety is a highly technical and controversial subject that has caused much heated debate and political concern. This article examines the problems involved in managing radioactive wastes and the techniques now used. Potential solutions are suggested and the need for international cooperation is stressed. (Author/MA)
Solution strategies for constant acceleration problems
NASA Astrophysics Data System (ADS)
Wheaton, S. M.; Binder, P.-M.
2017-03-01
We discuss strategies for the general solution of single-step 1D constant acceleration problems. In a slightly restricted form, these problems have five variables (Δx, v 0, v, a and t) and two independent equations, so three variables must be given to solve for the other two, giving 10 cases. Instead of the haphazard solution of individual problems, we advocate teaching a strategy for tackling the entire class of problems. We enumerate the possible strategies, and present in detail one which reveals a number of interesting special cases and also allows the possibility of developing an automatic problem generator and solver.
A Mathematical Solution to the Motorway Problem
ERIC Educational Resources Information Center
Michaelson, Matthew T.
2009-01-01
This article presents a mathematical solution to a motorway problem. The motorway problem is an excellent application in optimisation. As it integrates the concepts of trigonometric functions and differentiation, the motorway problem can be used quite effectively as the basis for an assessment tool in senior secondary mathematics subjects.…
Critical Heat Flux of Butanol Aqueous Solution
NASA Astrophysics Data System (ADS)
Nishiguchi, Shotaro; Shoji, Masahiro
It is known that the addition of small amount of alcohol such as butanol to water enhances the CHF. Such aqueous solution is actively applied to heat transfer devices such as heat pipes and microchannel cooling systems, however, the fundamental characters of boiling have not been fully understood. In the present research, the experiment of boiling heat transfer is performed on a heated wire by employing butanol aqueous solution as a typical test solution and by changing concentration 1-butanol and subcooling in a wide range. Bubbling aspects were observed using high-speed video camera. It is found from the experiment that CHF is 2 to 3 times higher than that of pure water and generating bubbles are tiny even at the saturated condition. The dependence of CHF on subcooling is found to be curious showing that CHF decreases first, takes a minimum, and then increases with increasing subcooling. These results suggest that the butanol aqueous solution is a promising liquid for the application of boiling to a small-scaled cooling device.
Asymptotic solution for heat convection-radiation equation
Mabood, Fazle; Ismail, Ahmad Izani Md; Khan, Waqar A.
2014-07-10
In this paper, we employ a new approximate analytical method called the optimal homotopy asymptotic method (OHAM) to solve steady state heat transfer problem in slabs. The heat transfer problem is modeled using nonlinear two-point boundary value problem. Using OHAM, we obtained the approximate analytical solution for dimensionless temperature with different values of a parameter ε. Further, the OHAM results for dimensionless temperature have been presented graphically and in tabular form. Comparison has been provided with existing results from the use of homotopy perturbation method, perturbation method and numerical method. For numerical results, we used Runge-Kutta Fehlberg fourth-fifth order method. It was found that OHAM produces better approximate analytical solutions than those which are obtained by homotopy perturbation and perturbation methods, in the sense of closer agreement with results obtained from the use of Runge-Kutta Fehlberg fourth-fifth order method.
Optimal solutions of unobservable orbit determination problems
NASA Astrophysics Data System (ADS)
Cicci, David A.; Tapley, Byron D.
1988-12-01
The method of data augmentation, in the form ofa priori covariance information on the reference solution, as a means to overcome the effects of ill-conditioning in orbit determination problems has been investigated. Specifically, for the case when ill-conditioning results from parameter non-observability and an appropriatea priori covariance is unknown, methods by which thea priori covariance is optimally chosen are presented. In problems where an inaccuratea priori covariance is provided, the optimal weighting of this data set is obtained. The feasibility of these ‘ridge-type’ solution methods is demonstrated by their application to a non-observable gravity field recovery simulation. In the simulation, both ‘ridge-type’ and conventional solutions are compared. Substantial improvement in the accuracy of the conventional solution is realized by the use of these ridge-type solution methods. The solution techniques presented in this study are applicable to observable, but ill-conditioned problems as well as the unobservable problems directly addressed. For the case of observable problems, the ridge-type solutions provide an improvement in the accuracy of the ordinary least squares solutions.
A Solution Framework for Environmental Characterization Problems
This paper describes experiences developing a grid-enabled framework for solving environmental inverse problems. The solution approach taken here couples environmental simulation models with global search methods and requires readily available computational resources of the grid ...
A Solution Framework for Environmental Characterization Problems
This paper describes experiences developing a grid-enabled framework for solving environmental inverse problems. The solution approach taken here couples environmental simulation models with global search methods and requires readily available computational resources of the grid ...
Internet Education: Potential Problems and Solutions.
ERIC Educational Resources Information Center
Sharma, Preeti; Maleyeff, John
2003-01-01
Highlights some of the unplanned consequences that might be encountered as the use of the Internet in education increases, categorizing them as potential problems of judgment, distance, and ethics. Suggests course design, pedagogical, and student activity solutions. (EV)
The Pizza Problem: A Solution with Sequences
ERIC Educational Resources Information Center
Shafer, Kathryn G.; Mast, Caleb J.
2008-01-01
This article addresses the issues of coaching and assessing. A preservice middle school teacher's unique solution to the Pizza problem was not what the professor expected. The student's solution strategy, based on sequences and a reinvention of Pascal's triangle, is explained in detail. (Contains 8 figures.)
The Pizza Problem: A Solution with Sequences
ERIC Educational Resources Information Center
Shafer, Kathryn G.; Mast, Caleb J.
2008-01-01
This article addresses the issues of coaching and assessing. A preservice middle school teacher's unique solution to the Pizza problem was not what the professor expected. The student's solution strategy, based on sequences and a reinvention of Pascal's triangle, is explained in detail. (Contains 8 figures.)
Heat Transfer Problems of Mixed Refrigerants
NASA Astrophysics Data System (ADS)
Fujii, Tetsu; Koyama, Shigeru; Goto, Masao; Takamatsu, Hiroshi
From the point of view of the application of non-azeotropic mixed refrigerants to heat pump and refrigeration cycles, literatures on condensation and evaporation are surveyed and future problems to be studied are extracted. All researches on the relevant problems are recently started and still in developing way except for condensation on a single horizontal tube. Particularly, the studies for condensation and evaporation of mixed Freon refrigerant in a horizontal tube, which are the most important in practice, are far backward in comparison with single component refrigerant in every point of heat transfer characteristics, flow pattern and theoretical analysis.
Helping Ourselves: Local Solutions to Global Problems.
ERIC Educational Resources Information Center
Stokes, Bruce
Solutions to global problems such as inflation, tightening energy supplies, and deteriorating environmental quality lie at the local level where the consequences are most obvious, the motivation to get involved is most direct, and the benefits of action are most immediate. Examples of problems regarding energy, the workplace, food production,…
Solution Strategies for Constant Acceleration Problems
ERIC Educational Resources Information Center
Wheaton, S. M.; Binder, P.-M.
2017-01-01
We discuss strategies for the general solution of single-step 1D constant acceleration problems. In a slightly restricted form, these problems have five variables (?"x," "v[subscript 0]," "v," "a" and "t") and two independent equations, so three variables must be given to solve for the other two,…
Algorithmic aspects of transient heat transfer problems in structures
NASA Technical Reports Server (NTRS)
Haftka, R. T.; Kadivar, M. H.
1982-01-01
It is noted that the application of finite element or finite difference techniques to the solution of transient heat transfer problems in structures often results in a stiff system of ordinary differential equations. Such systems are usually handled most efficiently by implicit integration techniques which require the solution of large and sparse systems of algebraic equations. The assembly and solution of these systems using the incomplete Cholesky conjugate gradient algorithm is examined. Several examples are used to demonstrate the advantage of the algorithm over other techniques.
Clustering of solutions in hard satisfiability problems
NASA Astrophysics Data System (ADS)
Ardelius, John; Aurell, Erik; Krishnamurthy, Supriya
2007-10-01
We study numerically the solution space structure of random 3-SAT problems close to the SAT/UNSAT transition. This is done by considering chains of satisfiability problems, where clauses are added sequentially to a problem instance. Using the overlap measure of similarity between different solutions found on the same problem instance, we examine geometrical changes as a function of α. In each chain, the overlap distribution is first smooth, but then develops a tiered structure, indicating that the solutions are found in well separated clusters. On chains of not too large instances, all remaining solutions are eventually observed to be found in only one small cluster before vanishing. This condensation transition point is estimated by finite size scaling to be αc = 4.26 with an apparent critical exponent of about 1.7. The average overlap value is also observed to increase with α up to the transition, indicating a reduction in solutions space size, in accordance with theoretical predictions. The solutions are generated by a local heuristic, ASAT, and compared to those found by the Survey Propagation algorithm up to αc.
NASTRAN solutions of problems described by simultaneous parabolic differential equations
NASA Technical Reports Server (NTRS)
Mason, J. B.; Walston, W. H., Jr.
1975-01-01
NASTRAN solution techniques are shown for a numerical analysis of a class of coupled vector flow processes described by simultaneous parabolic differential equations. To define one physical problem type where equations of this form arise, the differential equations describing the coupled transfers of heat and mass in mechanical equilibrium with negligible mass average velocity are presented and discussed. Also shown are the equations describing seepage when both electrokinetic and hydrodynamic forces occur. Based on a variational statement of the general problem type, the concepts of scalar transfer elements and parallel element systems are introduced. It is shown that adoptation of these concepts allows the direct use of NASTRAN's existing Laplace type elements for uncoupled flow (the heat transfer elements) for treating multicomponent coupled transfer. Sample problems are included which demonstrate the application of these techniques for both steady-state and transient problems.
The numerical solution of thermoporoelastoplasticity problems
NASA Astrophysics Data System (ADS)
Sivtsev, P. V.; Kolesov, A. E.; Sirditov, I. K.; Stepanov, S. P.
2016-10-01
Before constructing buildings in permafrost areas the careful study of stress-strain state of soils and building foundations must be performed in order to estimate their bearing capacity and stability to avoid issues with maintenance. To determine stress-strain state of frozen soils the numerical modeling of thermoporoelastoplasticity problems is used. The mathematical model of considered problems includes the elasto-plasticity equations and equations of heat and mass transfer with phase transition. The computational algorithm is based on the finite element approximation in space and the finite difference approximation in time. As the model problem we consider the deformation of soil under house weight and heating. Special attention is given to thawing of frozen soils, which can cause additional deformations and lead to loss of stability.
Solving nonlinear heat transfer constant area fin problems
NASA Technical Reports Server (NTRS)
1968-01-01
Tables and graphs were compiled for solving nonlinear heat transfer constant area fin problems. The differential equation describing one-dimensional steady-state temperature distribution and heat flow under three modes of heat transfer with heat generation was investigated.
[Heat-related problems in the elderly].
Karg, T; Rendenbach, U
2005-06-30
In particular in the elderly patient, exposure to heat can lead to disturbances of the circulatory system and of the water and electrolyte balance. Provided that certain prophylactic measures are taken, serious problems are unlikely to occur. Food and drink should be matched to the ambient temperature, and permanent medication should be checked. In the case of confused persons, nursing personnel should substitute for any failure to make the necessary acclimatization changes (appropriate clothing). In the case of incontinent patients, it must be remembered that the diapered area is not available for radiating off heat.
After-hours coverage: problems and solutions.
Wagner, Andrew L
2004-05-01
Among the problems facing many radiology groups today is how to cover after-hours studies, because the demand is increasing while the number of available radiologists is still relatively low. There are a number of possible solutions, each of which has its own pros and cons, and no solution is right for every group. Recently, there have been a number of companies whose sole business is providing outside teleradiology coverage of after-hours radiology studies, sometimes referred to as "nighthawk" services. This article describes one group's decision-making process in choosing to hire a nighttime teleradiology provider as well as its subsequent experiences and ideas for future solutions.
Simulators' validation study: Problem solution logic
NASA Technical Reports Server (NTRS)
Schoultz, M. B.
1974-01-01
A study was conducted to validate the ground based simulators used for aircraft environment in ride-quality research. The logic to the approach for solving this problem is developed. The overall problem solution flow chart is presented. The factors which could influence the human response to the environment on board the aircraft are analyzed. The mathematical models used in the study are explained. The steps which were followed in conducting the validation tests are outlined.
Solution of the Classical Stefan Problem: Neumann Condition
NASA Astrophysics Data System (ADS)
Kot, V. A.
2017-07-01
A polynomial solution of the classical one-phase Stefan problem with a Neumann boundary condition is presented. As a result of the multiple integration of the heat-conduction equation, a sequence of identical equalities has been obtained. On the basis of these equalities, solutions were constructed in the form of the second-, third-, fourth-, and fifth-degree polynomials. It is shown by test examples that the approach proposed is highly efficient and that the approximation errors of the solutions in the form of the fourth- and fifth-degree polynomials are negligible small, which allows them to be considered in fact as exact. The polynomial solutions obtained substantially surpass the analogous numerical solutions in the accuracy of determining the position of the moving interphase boundary in a body and are in approximate parity with them in the accuracy of determining the temperature profile in it.
Nonclassical Symmetry Analysis of Heated Two-Dimensional Flow Problems
NASA Astrophysics Data System (ADS)
Naeem, Imran; Naz, Rehana; Khan, Muhammad Danish
2015-12-01
This article analyses the nonclassical symmetries and group invariant solution of boundary layer equations for two-dimensional heated flows. First, we derive the nonclassical symmetry determining equations with the aid of the computer package SADE. We solve these equations directly to obtain nonclassical symmetries. We follow standard procedure of computing nonclassical symmetries and consider two different scenarios, ξ1≠0 and ξ1=0, ξ2≠0. Several nonclassical symmetries are reported for both scenarios. Furthermore, numerous group invariant solutions for nonclassical symmetries are derived. The similarity variables associated with each nonclassical symmetry are computed. The similarity variables reduce the system of partial differential equations (PDEs) to a system of ordinary differential equations (ODEs) in terms of similarity variables. The reduced system of ODEs are solved to obtain group invariant solution for governing boundary layer equations for two-dimensional heated flow problems. We successfully formulate a physical problem of heat transfer analysis for fluid flow over a linearly stretching porous plat and, with suitable boundary conditions, we solve this problem.
It's No Problem to Invent a Solution
ERIC Educational Resources Information Center
Graca, Rose M.
2012-01-01
A kindergarten class learns about inventions, inventors, and how to be an inventor. Engaging students in learning about pencil sharpeners led to researching and developing a lesson plan designed so students could learn how inventions are solutions to problems. Through identifying, researching, and brainstorming new inventions, the students…
Nature, Human Nature, and Solutions to Problems.
ERIC Educational Resources Information Center
Pedrini, D. T.; Pedrini, B. C.
This paper promotes an undergraduate course that would discuss the great ideas of Plato, St. Paul, Karl Marx, Sigmund Freud, Jean Paul Sartre, B. F. Skinner, and Konrad Lorenz. This course would help students understand human values and behaviors while focusing on historical, world, and national problems. Tentative solutions would then be…
The Hubble Space Telescope: Problems and Solutions.
ERIC Educational Resources Information Center
Villard, Ray
1990-01-01
Presented is the best understanding of the flaw discovered in the optics of the Hubble Space Telescope and the possible solutions to the problems. The spherical aberration in the telescope's mirror and its effect on the quality of the telescope's imaging ability is discussed. (CW)
The Hubble Space Telescope: Problems and Solutions.
ERIC Educational Resources Information Center
Villard, Ray
1990-01-01
Presented is the best understanding of the flaw discovered in the optics of the Hubble Space Telescope and the possible solutions to the problems. The spherical aberration in the telescope's mirror and its effect on the quality of the telescope's imaging ability is discussed. (CW)
It's No Problem to Invent a Solution
ERIC Educational Resources Information Center
Graca, Rose M.
2012-01-01
A kindergarten class learns about inventions, inventors, and how to be an inventor. Engaging students in learning about pencil sharpeners led to researching and developing a lesson plan designed so students could learn how inventions are solutions to problems. Through identifying, researching, and brainstorming new inventions, the students…
Nature, Human Nature, and Solutions to Problems.
ERIC Educational Resources Information Center
Pedrini, D. T.; Pedrini, B. C.
This paper promotes an undergraduate course that would discuss the great ideas of Plato, St. Paul, Karl Marx, Sigmund Freud, Jean Paul Sartre, B. F. Skinner, and Konrad Lorenz. This course would help students understand human values and behaviors while focusing on historical, world, and national problems. Tentative solutions would then be…
DNA computing of solutions to knapsack problems.
Henkel, Christiaan V; Bäck, Thomas; Kok, Joost N; Rozenberg, Grzegorz; Spaink, Herman P
2007-03-01
One line of DNA computing research focuses on parallel search algorithms, which can be used to solve many optimization problems. DNA in solution can provide an enormous molecular library, which can be searched by molecular biological techniques. We have implemented such a parallel search for solutions to knapsack problems, which ask for the best way to pack a knapsack of limited volume. Several instances of knapsack problems were solved using DNA. We demonstrate how the computations can be extended by in vivo translation of the DNA library into protein. This combination of DNA and protein allows for multi-criterion optimization. The knapsack computations performed can then be seen as protein optimizations, one of the most complex computations performed by natural systems.
Taming the heat flux problem: Advanced divertors towards fusion power
Kotschenreuther, M.; Mahajan, S.; Valanju, P. M.; Covele, B.; Waelbroeck, F. L.; Canik, John M.; LaBombard, Brian
2015-09-11
The next generation fusion machines are likely to face enormous heat exhaust problems. In addition to summarizing major issues and physical processes connected with these problems, we discuss how advanced divertors, obtained by modifying the local geometry, may yield workable solutions. We also point out that: (1) the initial interpretation of recent experiments show that the advantages, predicted, for instance, for the X-divertor (in particular, being able to run a detached operation at high pedestal pressure) correlate very well with observations, and (2) the X-D geometry could be implemented on ITER (and DEMOS) respecting all the relevant constraints. As a result, a roadmap for future research efforts is proposed.
Perturbation solutions of combustion instability problems
NASA Technical Reports Server (NTRS)
Googerdy, A.; Peddieson, J., Jr.; Ventrice, M.
1979-01-01
A method involving approximate modal analysis using the Galerkin method followed by an approximate solution of the resulting modal-amplitude equations by the two-variable perturbation method (method of multiple scales) is applied to two problems of pressure-sensitive nonlinear combustion instability in liquid-fuel rocket motors. One problem exhibits self-coupled instability while the other exhibits mode-coupled instability. In both cases it is possible to carry out the entire linear stability analysis and significant portions of the nonlinear stability analysis in closed form. In the problem of self-coupled instability the nonlinear stability boundary and approximate forms of the limit-cycle amplitudes and growth and decay rates are determined in closed form while the exact limit-cycle amplitudes and growth and decay rates are found numerically. In the problem of mode-coupled instability the limit-cycle amplitudes are found in closed form while the growth and decay rates are found numerically. The behavior of the solutions found by the perturbation method are in agreement with solutions obtained using complex numerical methods.
Existence of solutions of extremal problems
Rzhevskii, S.V.
1995-09-01
One of the main questions that arise in the investigation of extremal problems is the existence of solutions. The general approach to establishing solvability of extremal problems are typically in the form of sufficient conditions. In some cases, the verification of these conditions is quite complex. In this article, we consider the existence of solutions of the problem f(x) {r_arrow}inf, x {element_of}{Omega} defined by the nonempty closed set {Omega} in the n-dimensional Euclidean space R{sup n} and a continuous function f on {Omega}. We assume that for some set {Omega}{prime} {improper_subset} R{sup n} and some finite-valued continuous function {psi}(x) {le} 0 and the problem f(x){r_arrow}inf x {element_of} {Omega}{prime} has a finite value f{sub *} {equivalent_to} inf/x {element_of} {Omega} and a nonempty solution set X{sub *} {equivalent_to} (x {element_of} {Omega}{prime}{vert_bar}f(x) = f{sub *}{prime}).
Analytical solutions to matrix diffusion problems
Kekäläinen, Pekka
2014-10-06
We report an analytical method to solve in a few cases of practical interest the equations which have traditionally been proposed for the matrix diffusion problem. In matrix diffusion, elements dissolved in ground water can penetrate the porous rock surronuding the advective flow paths. In the context of radioactive waste repositories this phenomenon provides a mechanism by which the area of rock surface in contact with advecting elements is greatly enhanced, and can thus be an important delay mechanism. The cases solved are relevant for laboratory as well for in situ experiments. Solutions are given as integral representations well suited for easy numerical solution.
Application of CFD to aerothermal heating problems
NASA Astrophysics Data System (ADS)
Macaraeg, M. G.
1986-01-01
Numerical solutions of the compressible Navier-Stokes equations by an alternating direction implicit scheme, applied to two experimental investigations are presented. The first is cooling by injection of a gas jet through the nose of an ogive-cone, and the second is the aerothermal environment in the gap formed by the wing and elevon section of a test model of the space shuttle. The simulations demonstrate that accurate pressure calculations are easily obtained on a coarse grid, while convergence is obtained after the residual reduces by four orders of magnitude. Accurate heating rates, however, require a fine grid solution, with convergence requiring at least a reduction of six orders of magnitude in the residual. The effect of artificial dissipation on numerical results is also assessed.
Application of CFD to aerothermal heating problems
NASA Technical Reports Server (NTRS)
Macaraeg, M. G.
1986-01-01
Numerical solutions of the compressible Navier-Stokes equations by an alternating direction implicit scheme, applied to two experimental investigations are presented. The first is cooling by injection of a gas jet through the nose of an ogive-cone, and the second is the aerothermal environment in the gap formed by the wing and elevon section of a test model of the space shuttle. The simulations demonstrate that accurate pressure calculations are easily obtained on a coarse grid, while convergence is obtained after the residual reduces by four orders of magnitude. Accurate heating rates, however, require a fine grid solution, with convergence requiring at least a reduction of six orders of magnitude in the residual. The effect of artificial dissipation on numerical results is also assessed.
Composting of MSW: Needs, problems and solutions
Irwin, T.J.
1996-12-31
This paper is constructed of three complementary sections. The first section discusses the need for composting municipal solid waste (MSW). Too often as scientists and engineers the focus narrows to solve a specific problem within a system or to find the most cost effective solution. One habitually fails to examine concepts holistically due to tight schedules or work backlogs. One understands how things work and gets renumerated by the ability to scale up from the bench or pilot, keep costs down and to troubleshoot cranky processes. Sitting back to understand the reason why something like composting makes sense is a luxury one usually cannot afford. Section two discusses problems specific to MSW composting such as product quality, production stabilization, nuisance odors, and vector attraction. The final segment deals with some solutions to these difficulties.
A Novel Hypercomplex Solution to Kepler's Problem
NASA Astrophysics Data System (ADS)
Condurache, C.; Martinuşi, V.
2007-05-01
By using a Sundman like regularization, we offer a unified solution to Kepler's problem by using hypercomplex numbers. The fundamental role in this paper is played by the Laplace-Runge-Lenz prime integral and by the hypercomplex numbers algebra. The procedure unifies and generalizes the regularizations offered by Levi-Civita and Kustaanheimo-Stiefel. Closed form hypercomplex expressions for the law of motion and velocity are deduced, together with inedite hypercomplex prime integrals.
Travelers' Health: Problems with Heat and Cold
... for temperature swings. Prevention of Heat Disorders Heat Acclimatization Heat acclimatization is a process of physiologic adaptation ... there is no heat exposure. Physical Conditioning and Acclimatization Higher levels of physical fitness improve exercise tolerance ...
Gopinath, A.; Sadhal, S.S.; Jones, P.D.; Seyed-Yagoobi, J.; Woodbury, K.A.
1996-12-31
In the first section on heat transfer in microgravity, the papers cover phase-change phenomena and thermocapillary flows and surface effects. In the second section, several papers cover solution methods for radiative heat transfer while the rest cover heat transfer in low-temperature environments. The last section covers papers containing valuable information for thermal contact conductance of various materials plus papers on inverse problems in heat transfer. Separate abstracts were prepared for most papers in this volume.
Computational Solutions to the Protein Folding Problem,
1994-05-19
A TRIDENT SCHOLAR oN PROJECT REPORT 0 NO. 223 "Computational Solutions to the Protein Folding Problem" L T -’ ’r i SEP 2 7 1994 ýV UNITED STATES...potential energy function (Chapter II), 25 1 2 2 U = X• k( l 1 -lo) 2+ X.ko (8,-8o) 2+X.-[1l + cos (Pip + )] Equation 4.1 xei (C ¶±~12.4 a where ri, is...iterative process, a set of k >_ 2"t+ l distinct local minima are computed. This can be done with rela- tive ease by using an efficient unconstrained
Invasion Biology: Specific Problems and Possible Solutions.
Courchamp, Franck; Fournier, Alice; Bellard, Céline; Bertelsmeier, Cleo; Bonnaud, Elsa; Jeschke, Jonathan M; Russell, James C
2017-01-01
Biological invasions have been unambiguously shown to be one of the major global causes of biodiversity loss. Despite the magnitude of this threat and recent scientific advances, this field remains a regular target of criticism - from outright deniers of the threat to scientists questioning the utility of the discipline. This unique situation, combining internal strife and an unaware society, greatly hinders the progress of invasion biology. It is crucial to identify the specificities of this discipline that lead to such difficulties. We outline here 24 specificities and problems of this discipline and categorize them into four groups: understanding, alerting, supporting, and implementing the issues associated with invasive alien species, and we offer solutions to tackle these problems and push the field forward.
An extended classical solution of the droplet growth problem
NASA Technical Reports Server (NTRS)
Anderson, B. J.; Hallett, J.; Beesley, M.
1981-01-01
Problems of applying the classical kinetic theory to the growth of small droplets from vapor are examined. A solution for the droplet growth equation is derived which is based on the assumption of a diffusive field extending to the drop surface. The method accounts for partial thermal and mass accommodation at the interface and the kinetic limit to the mass and heat fluxes, and it avoids introducing the artifact of a discontinuity in the thermal and vapor field near the droplet. Consideration of the environmental fields in spherical geometry utilizing directional fluxes yields boundary values in terms of known parameters and a new Laplace transform integral.
Basic Health Physics: Problems and Solutions
NASA Astrophysics Data System (ADS)
Bevelacqua, Joseph John
1999-01-01
Radiation litigation, the cleanup and decommissioning of nuclear facilities, radon exposure, nuclear medicine, food irradiation, stricter regulatory climate--these are some of the reasons health physics and radiation protection professionals are increasingly called upon to upgrade their skills. Designed to prepare candidates for the American Board of Health Physics Comprehensive examination (Part I) and other certification examinations, Basic Health Physics: Problems and Solutions introduces professionals in the field to radiation protection principles and their practical application in routine and emergency situations. It features more than 650 worked examples illustrating concepts under discussion along with an in-depth coverage of sources of radiation, standards and regulations, biological effects of ionizing radiation, instrumentation, external and internal dosimetry, counting statistics, monitoring and interpretations, operational health physics, transportation and waste, nuclear emergencies, and more. Reflecting for the first time the true scope of health physics at an introductory level, Basic Health Physics: Problems and Solutions gives readers the tools to properly evaluate challenging situations in all areas of radiation protection, including the medical, university, power reactor, fuel cycle, research reactor, environmental, non-ionizing radiation, and accelerator health physics.
Monotonic solution of heterogeneous anisotropic diffusion problems
NASA Astrophysics Data System (ADS)
Aricò, Costanza; Tucciarelli, Tullio
2013-11-01
Anisotropic problems arise in various areas of science and engineering, for example groundwater transport and petroleum reservoir simulations. The pure diffusive anisotropic time-dependent transport problem is solved on a finite number of nodes, that are selected inside and on the boundary of the given domain, along with possible internal boundaries connecting some of the nodes. An unstructured triangular mesh, that attains the Generalized Anisotropic Delaunay condition for all the triangle sides, is automatically generated by properly connecting all the nodes, starting from an arbitrary initial one. The control volume of each node is the closed polygon given by the union of the midpoint of each side with the “anisotropic” circumcentre of each final triangle. A structure of the flux across the control volume sides similar to the standard Galerkin Finite Element scheme is derived. A special treatment of the flux computation, mainly based on edge swaps of the initial mesh triangles, is proposed in order to obtain a stiffness M-matrix system that guarantees the monotonicity of the solution. The proposed scheme is tested using several literature tests and the results are compared with analytical solutions, as well as with the results of other algorithms, in terms of convergence order. Computational costs are also investigated.
Solution of the Generalized Noah's Ark Problem.
Billionnet, Alain
2013-01-01
The phylogenetic diversity (PD) of a set of species is a measure of the evolutionary distance among the species in the collection, based on a phylogenetic tree. Such a tree is composed of a root, internal nodes, and leaves that correspond to the set of taxa under study. With each edge of the tree is associated a non-negative branch length (evolutionary distance). If a particular survival probability is associated with each taxon, the PD measure becomes the expected PD measure. In the Noah's Ark Problem (NAP) introduced by Weitzman (1998), these survival probabilities can be increased at some cost. The problem is to determine how best to allocate a limited amount of resources to maximize the expected PD of the considered species. It is easy to formulate the NAP as a (difficult) nonlinear 0-1 programming problem. The aim of this article is to show that a general version of the NAP (GNAP) can be solved simply and efficiently with any set of edge weights and any set of survival probabilities by using standard mixed-integer linear programming software. The crucial point to move from a nonlinear program in binary variables to a mixed-integer linear program, is to approximate the logarithmic function by the lower envelope of a set of tangents to the curve. Solving the obtained mixed-integer linear program provides not only a near-optimal solution but also an upper bound on the value of the optimal solution. We also applied this approach to a generalization of the nature reserve problem (GNRP) that consists of selecting a set of regions to be conserved so that the expected PD of the set of species present in these regions is maximized. In this case, the survival probabilities of different taxa are not independent of each other. Computational results are presented to illustrate potentialities of the approach. Near-optimal solutions with hypothetical phylogenetic trees comprising about 4000 taxa are obtained in a few seconds or minutes of computing time for the GNAP, and in
Wireless device connection problems and design solutions
NASA Astrophysics Data System (ADS)
Song, Ji-Won; Norman, Donald; Nam, Tek-Jin; Qin, Shengfeng
2016-09-01
Users, especially the non-expert users, commonly experience problems when connecting multiple devices with interoperability. While studies on multiple device connections are mostly concentrated on spontaneous device association techniques with a focus on security aspects, the research on user interaction for device connection is still limited. More research into understanding people is needed for designers to devise usable techniques. This research applies the Research-through-Design method and studies the non-expert users' interactions in establishing wireless connections between devices. The "Learning from Examples" concept is adopted to develop a study focus line by learning from the expert users' interaction with devices. This focus line is then used for guiding researchers to explore the non-expert users' difficulties at each stage of the focus line. Finally, the Research-through-Design approach is used to understand the users' difficulties, gain insights to design problems and suggest usable solutions. When connecting a device, the user is required to manage not only the device's functionality but also the interaction between devices. Based on learning from failures, an important insight is found that the existing design approach to improve single-device interaction issues, such as improvements to graphical user interfaces or computer guidance, cannot help users to handle problems between multiple devices. This study finally proposes a desirable user-device interaction in which images of two devices function together with a system image to provide the user with feedback on the status of the connection, which allows them to infer any required actions.
Real time solution of parameterised problems via Model Reduction techniques
NASA Astrophysics Data System (ADS)
Zlotnik, Sergio; Signorini, Marianna; Modesto, David
2016-04-01
Parameterised problems, in which the solution depends on space, time and a set of predefined parameters (e.g. material properties, boundary conditions, domain geometry, initial conditions, ...), can be solved with extremely high efficiency with Model Reduction techniques. Among these techniques the Proper Generalized Decomposition (PGD), has some very interesting features that will be investigated and presented in this work. The PGD technique involves two computational phases: first, one "offline" phase that can be computationally expensive but it is executed only once in a lifetime and, second, an "online" phase that is extremely fast and lightweight in computer resources. The possibilities of PGD are shown here via several example problems: i) heat transport parameterised in the material properties, boundary conditions and interface locations, ii) Stokes flow parameterised in the geometry domain, and iii) wave propagation parameterised in boundary conditions, material properties and interface locations. The extremely fast evaluation of PGD-solutions make them ideal to be used within inverse problems where the unknowns are the values of the parameters and the data consist in some partial observation of the solution field.
Landmine research: technology solutions looking for problems
NASA Astrophysics Data System (ADS)
Trevelyan, James P.
2004-09-01
The global landmine problem came to the attention of researchers in the mid 1990's and by 1997 several advanced and expensive sensor research programs had started. Yet, by the end of 2003, there is little sign of a major advance in the technology available to humanitarian demining programs. Given the motivation and dedication of researchers, public goodwill to support such programs, and substantial research resources devoted to the problem, it is worth asking why these programs do not seem to have had an impact on demining costs or casualty rates. Perhaps there are factors that have been overlooked. This paper reviews several research programs to gain a deeper understanding of the problem. A possible explanation is that researchers have accepted mistaken ideas on the nature of the landmine problems that need to be solved. The paper provides several examples where the realities of minefield conditions are quite different to what researchers have been led to believe. Another explanation may lie in the political and economic realities that drive the worldwide effort to eliminate landmines. Most of the resources devoted to landmine clearance programs come from humanitarian aid budgets: landmine affected countries often contribute only a small proportion because they have different priorities based on realistic risk-based assessment of needs and political views of local people. Some aid projects have been driven by the need to find a market for demining technologies rather than by user needs. Finally, there is a common misperception that costs in less developed countries are intrinsically low, reflecting low rates paid for almost all classes of skilled labour. When actual productivity is taken into account, real costs can be higher than industrialized countries. The costs of implementing technological solutions (even using simple technologies) are often significantly under-estimated. Some political decisions may have discouraged thorough investigation of cost
Anomalous solutions to the strong CP problem.
Hook, Anson
2015-04-10
We present a new mechanism for solving the strong CP problem using a Z_{2} discrete symmetry and an anomalous U(1) symmetry. A Z_{2} symmetry is used so that two gauge groups have the same theta angle. An anomalous U(1) symmetry makes the difference between the two theta angles physical and the sum unphysical. Two models are presented where the anomalous symmetry manifests itself in the IR in different ways. In the first model, there are massless bifundamental quarks, a solution reminiscent of the massless up quark solution. In the IR of this model, the η^{'} boson relaxes the QCD theta angle to the difference between the two theta angles-in this case zero. In the second model, the anomalous U(1) symmetry is realized in the IR as a dynamically generated mass term that has exactly the phase needed to cancel the theta angle. Both of these models make the extremely concrete prediction that there exist new colored particles at the TeV scale.
ERIC Educational Resources Information Center
Chow, Alan F.; Van Haneghan, James P.
2016-01-01
This study reports the results of a study examining how easily students are able to transfer frequency solutions to conditional probability problems to novel situations. University students studied either a problem solved using the traditional Bayes formula format or using a natural frequency (tree diagram) format. In addition, the example problem…
ERIC Educational Resources Information Center
Chow, Alan F.; Van Haneghan, James P.
2016-01-01
This study reports the results of a study examining how easily students are able to transfer frequency solutions to conditional probability problems to novel situations. University students studied either a problem solved using the traditional Bayes formula format or using a natural frequency (tree diagram) format. In addition, the example problem…
Nursing: not the problem, but leading solutions.
Smadu, Marlene; Shamian, Judith
2012-01-01
One of the major themes uncovered by Graham and Sibbald in their analysis of the 50-year-old issues of Hospital Administration in Canada (HAC) is the evolution of nursing. However, the HAC approach 50 years ago was that nursing was a problem to be solved, not a resource for health, the health system and the public, and that image would stay with nursing in Canada for many years to come. The recent commissioning by the Canadian Nurses Association of a National Expert Commission to examine sustainability of health and the healthcare system, and the resultant report, The Health of Our Nation, the Future of Our Health System: A Nursing Call to Action, released in June 2012, reflect a significantly different expectation about nurses and the nursing profession - they are not problems to be addressed, but are leading the solutions to better health, better care and better value. And patients are not passive recipients of care decided on by professionals alone, but central team members - "CEOs of their own healthcare" - in an inter-professional patient-/family-focused team that collectively supports people in their health journey. A number of examples of potential articles about and from nursing, based on the findings of the National Expert Commission, are included to illustrate how nursing should be reflected in an issue of HAC in 2012.
A Solution in Search of Problems
NASA Technical Reports Server (NTRS)
1981-01-01
Ferrofluids offered vast-problem solving potential. Under license for the NASA technology, Dr. Ronald Moskowitz and Dr. Ronald Rosensweig formed Ferrofluids Corporation. First problem they found a solution for was related to the manufacture of semiconductor "chips" for use in electronic systems. They developed a magnetic seal composed of ferrofluid and a magnetic circuit. Magnetic field confines the ferrofluid in the regions between the stationary elements and the rotary shaft of the seal. Result is a series of liquid barriers that totally bar passage of contaminants. Seal is virtually wear-proof and has a lifetime measured in billions of shaft revolutions. It has reduced maintenance, minimizes "downtime" of production equipment, and reduces the cost of expensive materials that had previously been lost through seal failures. Products based on ferrofluid are exclusion seals for computer disc drives and inertia dampers for stepper motors. Uses are performance-improving, failure-reducing coolants for hi-fi loudspeakers. Other applications include analytical instrumentation, medical equipment, industrial processes, silicon crystal growing furnaces, plasma processes, fusion research, visual displays, and automated machine tools.
Travelers' Health: Problems with Heat and Cold
... predisposing factor in heat illness. Dehydration also reduces exercise performance, decreases time to exhaustion, and increases internal heat load. Temperature and heart rate increase in direct proportion to the level of ...
ESPs: On- and offshore problems and solutions. Part 4
Lea, J.F.; Wells, M.R.; Bearden, J.L.; Wilson, L.; Shepler, R.; Lannom, R.
1996-03-01
This is the fourth in a multipart series on the usage of electrical submersible pumps. This installment deals with high temperature, design, power consumption, run life, sweep efficiency and miscellaneous problems. The final installment next month will include a complete list of references. The column heating ``ESPs`` refers to the number of ESPs reported installed. Although all of the topics in this series can be considered ways of increasing run life and solving problems, the Run Life table includes several topics that specifically help to increase run life. Two cases were identified where ESPs are used to increase the sweep efficiency of a flood. The Sweep Efficiency table summarizes case histories where fluids were produced without the production losses that normally plague high volume systems. The Miscellaneous-Overall table includes several solutions that were part of an overall plan to increase run life. These strategies included automation, running and pulling procedures and surveillance.
Locating CVBEM collocation points for steady state heat transfer problems
Hromadka, T.V.
1985-01-01
The Complex Variable Boundary Element Method or CVBEM provides a highly accurate means of developing numerical solutions to steady state two-dimensional heat transfer problems. The numerical approach exactly solves the Laplace equation and satisfies the boundary conditions at specified points on the boundary by means of collocation. The accuracy of the approximation depends upon the nodal point distribution specified by the numerical analyst. In order to develop subsequent, refined approximation functions, four techniques for selecting additional collocation points are presented. The techniques are compared as to the governing theory, representation of the error of approximation on the problem boundary, the computational costs, and the ease of use by the numerical analyst. ?? 1985.
Probabilistic Solution of Ill-Posed Problems in Computational Vision.
1987-03-01
SOLUTION OF ILL - POSED PROBLEMS IN 1/t I CAMBRIDGE ARTIFICIAL INTELLIGENCE LAB UNLASIIE...TECHNOLOGY ARTIFICIAL INTELLIGENCE LABORATORY A. I. Memo 897 March 1987 Probabilistic Solution of Ill - Posed Problems in Computational Vision J. Marroquin... solution (a) exists, (b) is unique and (c) depends continuously on the initial data. Ill - posed problems fail to satisfy one or more of these
Real-World Problems: Teachers' Evaluation of Pupils' Solutions
ERIC Educational Resources Information Center
Chacko, Indira
2007-01-01
This article scrutinizes the solutions of real-world problems by pupils and the evaluations of these by their teachers in a semi-rural school in Zimbabwe. Generally, real-world problems are solved as if these are standard problems expecting a solution and a correct answer. In most cases, the solutions of the pupils are considered correct by the…
Optimization of the heating surface shape in the contact melting problem
NASA Technical Reports Server (NTRS)
Fomin, Sergei A.; Cheng, Shangmo
1991-01-01
The theoretical analysis of contact melting by the migrating heat source with an arbitrary shaped isothermal heating surface is presented. After the substantiated simplification, the governing equations are transformed to the convenient equations for engineering calculations relationships. Analytical solutions are used for numerical prediction of optimal shape of the heating surface. The problem is investigated for the constant and for temperature dependent physical properties of the melt.
TOUGH Simulations of the Updegraff's Set of Fluid and Heat Flow Problems
Moridis, G.J.; Pruess , K.
1992-11-01
The TOUGH code [Pruess, 1987] for two-phase flow of water, air, and heat in penneable media has been exercised on a suite of test problems originally selected and simulated by C. D. Updegraff [1989]. These include five 'verification' problems for which analytical or numerical solutions are available, and three 'validation' problems that model laboratory fluid and heat flow experiments. All problems could be run without any code modifications (*). Good and efficient numerical performance, as well as accurate results were obtained throughout. Additional code verification and validation problems from the literature are briefly summarized, and suggestions are given for proper applications of TOUGH and related codes.
Hurricanes as Heat Engines: Two Undergraduate Problems
ERIC Educational Resources Information Center
Pyykko, Pekka
2007-01-01
Hurricanes can be regarded as Carnot heat engines. One reason that they can be so violent is that thermodynamically, they demonstrate large efficiency, [epsilon] = (T[subscript h] - T[subscript c]) / T[subscript h], which is of the order of 0.3. Evaporation of water vapor from the ocean and its subsequent condensation is the main heat transfer…
Hurricanes as Heat Engines: Two Undergraduate Problems
ERIC Educational Resources Information Center
Pyykko, Pekka
2007-01-01
Hurricanes can be regarded as Carnot heat engines. One reason that they can be so violent is that thermodynamically, they demonstrate large efficiency, [epsilon] = (T[subscript h] - T[subscript c]) / T[subscript h], which is of the order of 0.3. Evaporation of water vapor from the ocean and its subsequent condensation is the main heat transfer…
COYOTE: a finite-element computer program for nonlinear heat-conduction problems
Gartling, D.K.
1982-10-01
COYOTE is a finite element computer program designed for the solution of two-dimensional, nonlinear heat conduction problems. The theoretical and mathematical basis used to develop the code is described. Program capabilities and complete user instructions are presented. Several example problems are described in detail to demonstrate the use of the program.
Simulating water, solute, and heat transport in the subsurface with the VS2DI software package
Healy, R.W.
2008-01-01
The software package VS2DI was developed by the U.S. Geological Survey for simulating water, solute, and heat transport in variably saturated porous media. The package consists of a graphical preprocessor to facilitate construction of a simulation, a postprocessor for visualizing simulation results, and two numerical models that solve for flow and solute transport (VS2DT) and flow and heat transport (VS2DH). The finite-difference method is used to solve the Richards equation for flow and the advection-dispersion equation for solute or heat transport. This study presents a brief description of the VS2DI package, an overview of the various types of problems that have been addressed with the package, and an analysis of the advantages and limitations of the package. A review of other models and modeling approaches for studying water, solute, and heat transport also is provided. ?? Soil Science Society of America. All rights reserved.
Hydro-abrasive erosion: Problems and solutions
NASA Astrophysics Data System (ADS)
Winkler, K.
2014-03-01
The number of hydro power plants with hydro-abrasive erosion is increasing worldwide. An overall approach is needed to minimize the impact of this phenomenon. Already at the start of the planning phase an evaluation should be done to quantify the erosion and the impact on the operation. For this, the influencing parameters and their impact on the erosion have to be known. The necessary information for the evaluation comprises among others the future design, the particle parameters of the water, which will pass the turbine, and the power plant owner's framework for the future operation like availability or maximum allowable efficiency loss, before an overhaul needs to be done. Based on this evaluation of the erosion, an optimised solution can then be found, by analysing all measures in relation to investments, energy production and maintenance costs as decision parameters. Often a more erosion-resistant design, instead of choosing the turbine design with the highest efficiency, will lead to higher revenue. The paper will discuss the influencing parameters on hydro-abrasive erosion and the problems to acquire this information. There are different optimisation possibilities, which will be shown in different case studies. One key aspect to reduce the erosion and prolong the operation time of the components is to coat all relevant parts. But it is very important that this decision is taken early in the design stage, as the design has to be adapted to the requirements of the coating process. The quality of coatings and their impact on the operation will be discussed in detail in the paper as due to the non-availability of standards many questions arise in projects.
Asymptotic traveling wave solution for a credit rating migration problem
NASA Astrophysics Data System (ADS)
Liang, Jin; Wu, Yuan; Hu, Bei
2016-07-01
In this paper, an asymptotic traveling wave solution of a free boundary model for pricing a corporate bond with credit rating migration risk is studied. This is the first study to associate the asymptotic traveling wave solution to the credit rating migration problem. The pricing problem with credit rating migration risk is modeled by a free boundary problem. The existence, uniqueness and regularity of the solution are obtained. Under some condition, we proved that the solution of our credit rating problem is convergent to a traveling wave solution, which has an explicit form. Furthermore, numerical examples are presented.
Geometric Series: A New Solution to the Dog Problem
ERIC Educational Resources Information Center
Dion, Peter; Ho, Anthony
2013-01-01
This article describes what is often referred to as the dog, beetle, mice, ant, or turtle problem. Solutions to this problem exist, some being variations of each other, which involve mathematics of a wide range of complexity. Herein, the authors describe the intuitive solution and the calculus solution and then offer a completely new solution…
Ritchie, R.H.; Sakakura, A.Y.
1956-01-01
The formal solutions of problems involving transient heat conduction in infinite internally bounded cylindrical solids may be obtained by the Laplace transform method. Asymptotic series representing the solutions for large values of time are given in terms of functions related to the derivatives of the reciprocal gamma function. The results are applied to the case of the internally bounded infinite cylindrical medium with, (a) the boundary held at constant temperature; (b) with constant heat flow over the boundary; and (c) with the "radiation" boundary condition. A problem in the flow of gas through a porous medium is considered in detail.
The Finite Analytic Method for steady and unsteady heat transfer problems
NASA Technical Reports Server (NTRS)
Chen, C.-J.; Li, P.
1980-01-01
A new numerical method called the Finite Analytical Method for solving partial differential equations is introduced. The basic idea of the finite analytic method is the incorporation of the local analytic solution in obtaining the numerical solution of the problem. The finite analytical method first divides the total region of the problem into small subregions in which local analytic solutions are obtained. Then an algebraic equation is derived from the local analytic solution for each subregion relating an interior nodal value at a point P in the subregion to its neighboring nodal values. The assembly of all the local analytic solutions thus provides the finite-analytic numerical solution of the problem. In this paper the finite analytic method is illustrated in solving steady and unsteady heat transfer problems.
Closed solutions for model problems in generalized thermoelasticity
NASA Astrophysics Data System (ADS)
Lychev, S. A.; Klindukhov, V. V.
2017-01-01
Closed solutions for model problems in non-dissipative thermoelasticity are obtained. The solutions are in the form of spectral expansion over biorthogonal system of eigenfunctions corresponded to mutual conjugate pair of operator pencils.
The residential space heating problem in Lithuania
Kazakevicius, E.; Schipper, L.; Meyers, S.
1996-02-01
This report gives preliminary data on housing in Lithuania. We focus on the actual housing structure now that much of the stock has been privatized-an action that carries with it uncertainty regarding who is responsible for heating energy use, who is responsible for conservation measures and retrofitting, and who benefits from these actions. The paper then discusses some of the measures undertaken by both property owners and by governmental agencies to ameliorate poor heating conditions. The report summarizes results from a number of recent studies of the potential for energy savings in heating Lithuanian multifamily buildings. In closing we recommend actions that should be taken soon to ensure that Lithuanian housing moves along a path to greater energy efficiency. Some signals as to where this path should go can be taken from European countries with similar climatic conditions.
Solution of a Simple Inelastic Scattering Problem
ERIC Educational Resources Information Center
Knudson, Stephen K.
1975-01-01
Provides an analytical solution of a model representing the collision of an atom with a harmonic oscillator, interacting via a repulsive square well potential. Presents results for various energies and strengths of inelastic scattering. (Author/CP)
Nonlinear Transient Problems Using Structure Compatible Heat Transfer Code
NASA Technical Reports Server (NTRS)
Hou, Gene
2000-01-01
The report documents the recent effort to enhance a transient linear heat transfer code so as to solve nonlinear problems. The linear heat transfer code was originally developed by Dr. Kim Bey of NASA Largely and called the Structure-Compatible Heat Transfer (SCHT) code. The report includes four parts. The first part outlines the formulation of the heat transfer problem of concern. The second and the third parts give detailed procedures to construct the nonlinear finite element equations and the required Jacobian matrices for the nonlinear iterative method, Newton-Raphson method. The final part summarizes the results of the numerical experiments on the newly enhanced SCHT code.
Institutional solutions to drinking water problems: Maine case studies
Not Available
1993-03-01
The paper recounts how four Maine communities sought and found institutional solutions to drinking water problems. Each scenario describes the system, outlines the problems, reviews the chronology of events, points out the lessons learned and gives the system's current status.
Turning Muddy Problems into Clear Solutions
ERIC Educational Resources Information Center
Neil, Thomas C.
1975-01-01
Author discusses some aspects of counseling process. Makes suggestions of how to sift through maze of distractions and generalizations counselees present as problems and how to change latter into concrete statements that reflect their true nature and indicate how to resolve them. Finally, author describes strategies that help solve problems. (SE)
Articulation and Transfer: Definitions, Problems, and Solutions.
ERIC Educational Resources Information Center
Wright, M. Irene; And Others
Although the Maricopa County Community College District (MCCCD), in Arizona, maintains an exemplary relationship and numerous transfer agreements with the state's public universities, systematic and operational problems still exist. Systematic problems include the accumulation of excessive college credit hours; changes in applicable transfer…
DNA solution of the maximal clique problem.
Ouyang, Q; Kaplan, P D; Liu, S; Libchaber, A
1997-10-17
The maximal clique problem has been solved by means of molecular biology techniques. A pool of DNA molecules corresponding to the total ensemble of six-vertex cliques was built, followed by a series of selection processes. The algorithm is highly parallel and has satisfactory fidelity. This work represents further evidence for the ability of DNA computing to solve NP-complete search problems.
Teaching Computer Science through Problems, Not Solutions
ERIC Educational Resources Information Center
Fee, Samuel B.; Holland-Minkley, Amanda M.
2010-01-01
Regardless of the course topic, every instructor in a computing field endeavors to engage their students in deep problem-solving and critical thinking. One of the specific learning outcomes throughout our computer science curriculum is the development of independent, capable problem solving--and we believe good pedagogy can bring such about. Our…
Convective Heat Transfer Characteristics of NaHCO3-Ag Nano Compound Material Solution
NASA Astrophysics Data System (ADS)
Kang, Byung Ha; Heo, Juyeong; Kim, Kyung Jae
Convection heat transfer enhancement is an important issue since this problem is of particular interest in the field of energy and environment. Ag nano-solution is expected not only to enhance heat transfer but also to work for deodorization and antifungal effect. An experimental investigation on the convective heat transfer characteristics for NaHCO3-Ag nano-compound material solution in a long and straight heated pipe has been carried out. NaHCO3 compound materials with 400 ppm or 1000 ppm Ag nano-particle solved in pure water are considered to study the effect of Ag nano-particle on the heat transfer enhancement. The concentration of NaHCO3-Ag compound material in the water is varied 0.1 % to 1.0 %. The results indicate that the convective heat transfer coefficient is increased with an increase in the concentration of NaHCO3-Ag compound solution. At a given concentration, heat transfer coefficient is increased as the content of the Ag nano-particle is increased. Heat transfer enhancement ratio correlation using NaHCO3-Ag compound solution is also suggested.
Inverse modeling for heat conduction problem in human abdominal phantom.
Huang, Ming; Chen, Wenxi
2011-01-01
Noninvasive methods for deep body temperature measurement are based on the principle of heat equilibrium between the thermal sensor and the target location theoretically. However, the measurement position is not able to be definitely determined. In this study, a 2-dimensional mathematical model was built based upon some assumptions for the physiological condition of the human abdomen phantom. We evaluated the feasibility in estimating the internal organs temperature distribution from the readings of the temperature sensors arranged on the skin surface. It is a typical inverse heat conduction problem (IHCP), and is usually mathematically ill-posed. In this study, by integrating some physical and physiological a-priori information, we invoked the quasi-linear (QL) method to reconstruct the internal temperature distribution. The solutions of this method were improved by increasing the accuracy of the sensors and adjusting their arrangement on the outer surface, and eventually reached the state of converging at the best state accurately. This study suggests that QL method is able to reconstruct the internal temperature distribution in this phantom and might be worthy of a further study in an anatomical based model.
Equivalence of Two Solutions of Wahba's Problem
NASA Astrophysics Data System (ADS)
Markley, F. Landis
2013-12-01
Many attitude estimation methods are based on an optimization problem posed in 1965 by Grace Wahba. All these methods yield the same optimal estimate, except for inevitable computer roundoff errors. This note shows shows that Shuster's Quaternion Estimator (QUEST) and Mortari's Estimator of the Optimal Quaternion (ESOQ) are essentially identical even in the presence of roundoff errors. It also shows some connections between two other algorithms for solving Wahba's problem: Davenport's q method and the Singular Value Decomposition (SVD) method.
Toward a solution of the coincidence problem
Campo, Sergio del; Herrera, Ramon; Pavon, Diego
2008-07-15
The coincidence problem of late cosmic acceleration constitutes a serious riddle with regard to our understanding of the evolution of the Universe. Here we argue that this problem may someday be solved - or better understood - by expressing the Hubble expansion rate as a function of the ratio of densities (dark matter/dark energy) and observationally determining the said rate in terms of the redshift.
Optimal recovery of the solution of the heat equation from inaccurate data
Magaril-Il'yaev, G G; Osipenko, Konstantin Yu
2009-06-30
The problem of optimal recovery of the solution of the heat equation in the entire space at a fixed instant of time from inaccurate observations of this solution at some other instants of time is investigated. Explicit expressions for an optimal recovery method and its error are given. The solution of a similar problem with a priori information about the temperature distribution at some instants of time is also given. In all cases the optimal method uses information about at most two observations. Bibliography: 22 titles.
Student Health Insurance: Problems and Solutions
ERIC Educational Resources Information Center
Wagner, Robin
2006-01-01
Student health insurance experiences the same inflationary trends as employee benefits, but is rarely viewed as a significant direct cost to an institution, nor is the bill as high as the costs associated with employee health plans. Several long-term solutions and strategies that could help colleges to contain the ever-escalating cost of providing…
Classroom Acoustics: The Problem, Impact, and Solution.
ERIC Educational Resources Information Center
Berg, Frederick S.; And Others
1996-01-01
This article describes aspects of classroom acoustics that interfere with the ability of listeners to understand speech. It considers impacts on students and teachers and offers four possible solutions: noise control, signal control without amplification, individual amplification systems, and sound field amplification systems. (Author/DB)
Student Health Insurance: Problems and Solutions
ERIC Educational Resources Information Center
Wagner, Robin
2006-01-01
Student health insurance experiences the same inflationary trends as employee benefits, but is rarely viewed as a significant direct cost to an institution, nor is the bill as high as the costs associated with employee health plans. Several long-term solutions and strategies that could help colleges to contain the ever-escalating cost of providing…
Alternative Solutions for Optimization Problems in Generalizability Theory.
ERIC Educational Resources Information Center
Sanders, Piet F.
1992-01-01
Presents solutions for the problem of maximizing the generalizability coefficient under a budget constraint. Shows that the Cauchy-Schwarz inequality can be applied to derive optimal continuous solutions for the number of conditions of each facet. Illustrates the formal similarity between optimization problems in survey sampling and…
Alternative Solutions for Optimization Problems in Generalizability Theory.
ERIC Educational Resources Information Center
Sanders, Piet F.
1992-01-01
Presents solutions for the problem of maximizing the generalizability coefficient under a budget constraint. Shows that the Cauchy-Schwarz inequality can be applied to derive optimal continuous solutions for the number of conditions of each facet. Illustrates the formal similarity between optimization problems in survey sampling and…
Inverse problems and optimal experiment design in unsteady heat transfer processes identification
NASA Technical Reports Server (NTRS)
Artyukhin, Eugene A.
1991-01-01
Experimental-computational methods for estimating characteristics of unsteady heat transfer processes are analyzed. The methods are based on the principles of distributed parameter system identification. The theoretical basis of such methods is the numerical solution of nonlinear ill-posed inverse heat transfer problems and optimal experiment design problems. Numerical techniques for solving problems are briefly reviewed. The results of the practical application of identification methods are demonstrated when estimating effective thermophysical characteristics of composite materials and thermal contact resistance in two-layer systems.
Multigrid solution strategies for adaptive meshing problems
NASA Technical Reports Server (NTRS)
Mavriplis, Dimitri J.
1995-01-01
This paper discusses the issues which arise when combining multigrid strategies with adaptive meshing techniques for solving steady-state problems on unstructured meshes. A basic strategy is described, and demonstrated by solving several inviscid and viscous flow cases. Potential inefficiencies in this basic strategy are exposed, and various alternate approaches are discussed, some of which are demonstrated with an example. Although each particular approach exhibits certain advantages, all methods have particular drawbacks, and the formulation of a completely optimal strategy is considered to be an open problem.
The Aral Sea: problems, legends, solutions.
Kamalov, Yu
2003-01-01
A lot of legends have been created around the Aral Sea. Some of them were born during the Soviet time but there are already new ones that have arrived recently. Those legends came to be the barriers to solving the problem. There are also barriers created by the status quo mentality of local authorities. But mutual understanding is the biggest problem among countries sharing water resources. It is suggested to create an Ecological Economics Unit of the Biosphere (EEUB) managed by an executive body not affiliated to any country. Despite the borders the EEUB should unite the economics of neighborhood countries to protect the nature.
Solubility and prediction of the heat of solution of sodium naproxen in aqueous solutions.
Kim, Young-Soo; Méndez del Río, José R; Rousseau, Ronald W
2005-09-01
The solubility of sodium naproxen was determined over a range of temperatures from 15.2 degrees C to 39.7 degrees C by two methods: analyses of samples from equilibrated solutions and a recently developed procedure utilizing a focused-beam reflectance method (FBRM). The results demonstrate the utility of the newer and, in some cases, simpler method. A discontinuity in the solubility was observed at 29.8 degrees C, identifying the temperature as which the dihydrate and anhydrous forms of sodium naproxen trade places as being the more stable of the two forms. The heats of solution for the two pseudopolymorphs were obtained from van't Hoff plots of the solubility data. These results were used to demonstrate how the heat of solution of one form can be estimated using the heat of dehydration obtained from differential scanning calorimetry (DSC) and the heat of solution from another form.
Cosmic strings - A problem or a solution?
NASA Technical Reports Server (NTRS)
Bennett, David P.; Bouchet, Francois R.
1988-01-01
The most fundamental issue in the theory of cosmic strings is addressed by means of Numerical Simulations: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, results are presented which, though still preliminary, offer the best support to date of this scaling hypothesis.
Exact optimal solution for a class of dual control problems
NASA Astrophysics Data System (ADS)
Cao, Suping; Qian, Fucai; Wang, Xiaomei
2016-07-01
This paper considers a discrete-time stochastic optimal control problem for which only measurement equation is partially observed with unknown constant parameters taking value in a finite set of stochastic systems. Because of the fact that the cost-to-go function at each stage contains variance and the non-separability of the variance is so complicated that the dynamic programming cannot be successfully applied, the optimal solution has not been found. In this paper, a new approach to the optimal solution is proposed by embedding the original non-separable problem into a separable auxiliary problem. The theoretical condition on which the optimal solution of the original problem can be attained from a set of solutions of the auxiliary problem is established. In addition, the optimality of the interchanging algorithm is proved and the analytical solution of the optimal control is also obtained. The performance of this controller is illustrated with a simple example.
Solution of a Complex Least Squares Problem with Constrained Phase.
Bydder, Mark
2010-12-30
The least squares solution of a complex linear equation is in general a complex vector with independent real and imaginary parts. In certain applications in magnetic resonance imaging, a solution is desired such that each element has the same phase. A direct method for obtaining the least squares solution to the phase constrained problem is described.
The Effect of Alternative Solutions on Problem Solving Performance
ERIC Educational Resources Information Center
Lee, Shin-Yi
2011-01-01
The purpose of this study was to investigate the effect of instruction in alternative solutions on Taiwanese eighth-grade students' mathematical problem solving performance. This study was exploratory rather than experimental. Alternative-Solution Worksheet (ASW) was developed to encourage students' engagement with alternative solutions to…
Minimal Solutions to the Box Problem
ERIC Educational Resources Information Center
Chuang, Jer-Chin
2009-01-01
The "box problem" from introductory calculus seeks to maximize the volume of a tray formed by folding a strictly rectangular sheet from which identical squares have been cut from each corner. In posing such questions, one would like to choose integral side-lengths for the sheet so that the excised squares have rational or integral side-length.…
Can False Memories Prime Problem Solutions?
ERIC Educational Resources Information Center
Howe, Mark L.; Garner, Sarah R.; Dewhurst, Stephen A.; Ball, Linden J.
2010-01-01
Previous research has suggested that false memories can prime performance on related implicit and explicit memory tasks. The present research examined whether false memories can also be used to prime higher order cognitive processes, namely, insight-based problem solving. Participants were asked to solve a number of compound remote associate task…
Solutions to the Triangular Bicycle Flags Problem
ERIC Educational Resources Information Center
Hartweg, Kim
2005-01-01
Students in a fifth-grade general education class and a second-grade gifted class participated in the Triangular Bicycle Flags problem. The results indicated that providing students with geometric experiences at the correct van Hiele level is necessary for helping students move from one level of understanding to the next.
General Problem Solving: Navy Requirements and Solutions.
1985-03-01
Applied Mathematical Problem Solving, ERIC Clearinghouse for Science, Mathematics and Environmental Education , Columbus, Ohio, 1979. Bourne, Lyle...Mathematics and Environmental Education , Columbus, Ohio, 1979. Lewis, Clayton and Mack, Robert L. "The Role of Abduction in Learning to Use a
Minimal Solutions to the Box Problem
ERIC Educational Resources Information Center
Chuang, Jer-Chin
2009-01-01
The "box problem" from introductory calculus seeks to maximize the volume of a tray formed by folding a strictly rectangular sheet from which identical squares have been cut from each corner. In posing such questions, one would like to choose integral side-lengths for the sheet so that the excised squares have rational or integral side-length.…
Problem Solvers: Solutions--Playing Basketball
ERIC Educational Resources Information Center
Smith, Jeffrey
2014-01-01
In this article, fourth grade Upper Allen Elementary School (Mechanicsburg, Pennsylvania) teacher Jeffrey Smith describes his exploration of the Playing Basketball activity. Herein he describes how he found the problem to be an effective way to review concepts associated with the measurement of elapsed time with his students. Additionally, it…
English Preservice Teaching: Problems and Suggested Solutions
ERIC Educational Resources Information Center
Naeem, Marwa Ahmed Refat
2014-01-01
The present study investigated the problems faced by Egyptian EFL prospective teachers during their first encounter with preservice teaching. The sample for the study included 135 prospective EFL teachers trained in five preparatory (middle) schools in Kafr El-Sheikh city, Egypt. At the end of their first year training course, the prospective…
Real Problems, Virtual Solutions: Engaging Students Online
ERIC Educational Resources Information Center
Pearson, A. Fiona
2010-01-01
In this article, the author explains how she used online blogs with more than 263 students over a period of four semesters in an introductory social problems course. She describes how she uses blogs to enhance student participation, engagement, and skill building. Finally, she provides an overview of students' qualitative assessments of the blog…
Solutions to the Triangular Bicycle Flags Problem
ERIC Educational Resources Information Center
Hartweg, Kim
2005-01-01
Students in a fifth-grade general education class and a second-grade gifted class participated in the Triangular Bicycle Flags problem. The results indicated that providing students with geometric experiences at the correct van Hiele level is necessary for helping students move from one level of understanding to the next.
Viruses in Water: The Problem, Some Solutions
ERIC Educational Resources Information Center
Gerba, Charles P.; And Others
1975-01-01
Increasing population and industrialization places heavy demands on water resources making recycling of wastewaters for domestic consumption inevitable. Eliminating human pathogenic viruses is a major problem of reclaiming wastewater. Present water treatment methods may not be sufficient to remove viruses. (MR)
Problem Solvers: Solutions--The Inaugural Address
ERIC Educational Resources Information Center
Dause, Emily
2014-01-01
Fourth graders in Miss Dause's and Mrs. Hicks's mathematics classes at South Mountain Elementary School in Dillsburg, Pennsylvania, worked with the data from the Inauagural Address problem that was previously published published in the February 2013 issue of "Teaching Children Mathematics". This activity allowed students to showcase…
Can False Memories Prime Problem Solutions?
ERIC Educational Resources Information Center
Howe, Mark L.; Garner, Sarah R.; Dewhurst, Stephen A.; Ball, Linden J.
2010-01-01
Previous research has suggested that false memories can prime performance on related implicit and explicit memory tasks. The present research examined whether false memories can also be used to prime higher order cognitive processes, namely, insight-based problem solving. Participants were asked to solve a number of compound remote associate task…
Viruses in Water: The Problem, Some Solutions
ERIC Educational Resources Information Center
Gerba, Charles P.; And Others
1975-01-01
Increasing population and industrialization places heavy demands on water resources making recycling of wastewaters for domestic consumption inevitable. Eliminating human pathogenic viruses is a major problem of reclaiming wastewater. Present water treatment methods may not be sufficient to remove viruses. (MR)
Problem Solvers: Solutions--The Inaugural Address
ERIC Educational Resources Information Center
Dause, Emily
2014-01-01
Fourth graders in Miss Dause's and Mrs. Hicks's mathematics classes at South Mountain Elementary School in Dillsburg, Pennsylvania, worked with the data from the Inauagural Address problem that was previously published published in the February 2013 issue of "Teaching Children Mathematics". This activity allowed students to showcase…
Problem Solvers: Solutions--Playing Basketball
ERIC Educational Resources Information Center
Smith, Jeffrey
2014-01-01
In this article, fourth grade Upper Allen Elementary School (Mechanicsburg, Pennsylvania) teacher Jeffrey Smith describes his exploration of the Playing Basketball activity. Herein he describes how he found the problem to be an effective way to review concepts associated with the measurement of elapsed time with his students. Additionally, it…
Real Problems, Virtual Solutions: Engaging Students Online
ERIC Educational Resources Information Center
Pearson, A. Fiona
2010-01-01
In this article, the author explains how she used online blogs with more than 263 students over a period of four semesters in an introductory social problems course. She describes how she uses blogs to enhance student participation, engagement, and skill building. Finally, she provides an overview of students' qualitative assessments of the blog…
Analytical Solution for Three-Dimensional, Unsteady Heat Conduction in a Multilayer Sphere
Singh, Suneet; Jain, Prashant K.; Uddin, Rizwan
2016-06-07
An analytical solution has been obtained for the transient problem of three-dimensional multilayer heat conduction in a sphere with layers in the radial direction. The solution procedure can be applied to a hollow sphere or a solid sphere composed of several layers of various materials. In general, the separation of variables applied to 3D spherical coordinates has unique characteristics due to the presence of associated Legendre functions as the eigenfunctions. Moreover, an eigenvalue problem in the azimuthal direction also requires solution; again, its properties are unique owing to periodicity in the azimuthal direction. Therefore, extending existing solutions in 2D sphericalmore » coordinates to 3D spherical coordinates is not straightforward. In a spherical coordinate system, one can solve a 3D transient multilayer heat conduction problem without the presence of imaginary eigenvalues. A 2D cylindrical polar coordinate system is the only other case in which such multidimensional problems can be solved without the use of imaginary eigenvalues. The absence of imaginary eigenvalues renders the solution methodology significantly more useful for practical applications. The methodology described can be used for all three types of boundary conditions in the outer and inner surface of the sphere. Lastly, the solution procedure is demonstrated on an illustrative problem for which results are obtained.« less
Analytical Solution for Three-Dimensional, Unsteady Heat Conduction in a Multilayer Sphere
Singh, Suneet; Jain, Prashant K.; Uddin, Rizwan
2016-06-07
An analytical solution has been obtained for the transient problem of three-dimensional multilayer heat conduction in a sphere with layers in the radial direction. The solution procedure can be applied to a hollow sphere or a solid sphere composed of several layers of various materials. In general, the separation of variables applied to 3D spherical coordinates has unique characteristics due to the presence of associated Legendre functions as the eigenfunctions. Moreover, an eigenvalue problem in the azimuthal direction also requires solution; again, its properties are unique owing to periodicity in the azimuthal direction. Therefore, extending existing solutions in 2D spherical coordinates to 3D spherical coordinates is not straightforward. In a spherical coordinate system, one can solve a 3D transient multilayer heat conduction problem without the presence of imaginary eigenvalues. A 2D cylindrical polar coordinate system is the only other case in which such multidimensional problems can be solved without the use of imaginary eigenvalues. The absence of imaginary eigenvalues renders the solution methodology significantly more useful for practical applications. The methodology described can be used for all three types of boundary conditions in the outer and inner surface of the sphere. Lastly, the solution procedure is demonstrated on an illustrative problem for which results are obtained.
Optimization based inversion method for the inverse heat conduction problems
NASA Astrophysics Data System (ADS)
Mu, Huaiping; Li, Jingtao; Wang, Xueyao; Liu, Shi
2017-05-01
Precise estimation of the thermal physical properties of materials, boundary conditions, heat flux distributions, heat sources and initial conditions is highly desired for real-world applications. The inverse heat conduction problem (IHCP) analysis method provides an alternative approach for acquiring such parameters. The effectiveness of the inversion algorithm plays an important role in practical applications of the IHCP method. Different from traditional inversion models, in this paper a new inversion model that simultaneously highlights the measurement errors and the inaccurate properties of the forward problem is proposed to improve the inversion accuracy and robustness. A generalized cost function is constructed to convert the original IHCP into an optimization problem. An iterative scheme that splits a complicated optimization problem into several simpler sub-problems and integrates the superiorities of the alternative optimization method and the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm is developed for solving the proposed cost function. Numerical experiment results validate the effectiveness of the proposed inversion method.
[Priming effects in picture problems: preliminary solutions].
Wippich, W; Mecklenbräuker, S; Weidmann, K; Reichert, A
1995-01-01
Two experiments explored whether picture puzzles are an adequate instrument to investigate implicit memory for pictorial information. During the testing phase, the subjects had to identify hidden figures in picture puzzles. In a preceding learning phase, the priming conditions were varied systematically. In the first experiment, some subjects had to solve picture puzzles in the learning phase, whereas others made esthetic judgments (global processing) or estimated the number of triangles in the picture puzzles (local processing). In the second experiment, the subjects inspected copies of figures that were hidden at testing, modified versions of these figures, or their names in the learning phase. In the first experiment, the subjects of the different encoding conditions showed comparable priming effects. Picture puzzles that had already been processed or seen during learning were solved more often than new ones. Interview data revealed that subjects in the local or global processing conditions did not identify hidden figures at encoding. Furthermore, these subjects could not discriminate between old and new picture puzzles in a final explicit test of recognition. Thus, nonconscious storage of perceptual information that is not semantically interpreted may be sufficient to evoke priming effects. In the second experiment, the subjects in the different encoding conditions showed reliable priming effects, too. The presentation of the duplicates at encoding produced the greatest amount of priming. Effects of verbal priming, however, indicate that the solution of picture puzzles is not based solely on perceptual information. Depending on the priming conditions at learning, the solution of picture puzzles may be based primarily on data-driven processing or may be guided more heavily by conceptual information. It is concluded that perceptual, lexical, and/or conceptual information can contribute to the solution of picture puzzles.
Formulation and Solution of Economic Equilibrium Problems
1988-04-01
details along the way. Thank you, Charles and Mary Bess, my parents, for always making sure that it was possible for me to spend my years at Harvard...and here at Stanford. Thank you also, I think, for doing whatever it was you did to make me the perfectionist I am today. Maybe now I can give it a...as given exogenously. This important difference has implications for the mathematical properties of the problems which, on the whole, make partial
Recommended Solutions to Fire Fighting Training Problems,
1982-02-01
L. MALOY, Ed-D Training Analysis and Evaluation Group Deputy Chief of Naval Education and Training for Educational Development/ Research , Development...responsibility would ensure coordinated responses to senior commands, prevent duplication and interference of research and development efforts with... research rr t into the instructor communications problem in order to provide instrurte t -i f-re fighting schools with safe, satisfactory equipment. It is
Ergonomics problems and solutions in biotechnology laboratories
Coward, T.W.; Stengel, J.W.; Fellingham-Gilbert, P.
1995-03-01
The multi-functional successful ergonomics program currently implemented at Lawrence Livermore National Laboratory (LLNL) will be presented with special emphasis on recent findings in the Biotechnology laboratory environment. In addition to a discussion of more traditional computer-related repetitive stress injuries and associated statistics, the presentation will cover identification of ergonomic problems in laboratory functions such as pipetting, radiation shielding, and microscope work. Techniques to alleviate symptoms and prevent future injuries will be presented.
Marine geodesy - Problem areas and solution concepts
NASA Technical Reports Server (NTRS)
Saxena, N.
1974-01-01
This paper deals with a conceptional geodetic approach to solve various oceanic problems, such as submersible navigation under iced seas, demarcation/determination of boundaries in open ocean, resolving sea-level slope discrepancy, improving tsunami warning system, ecology, etc., etc. The required instrumentation is not described here. The achieved as well as desired positional accuracy estimates in open ocean for various tasks are also given.
Marine geodesy - Problem areas and solution concepts
NASA Technical Reports Server (NTRS)
Saxena, N.
1974-01-01
This paper deals with a conceptional geodetic approach to solve various oceanic problems, such as submersible navigation under iced seas, demarcation/determination of boundaries in open ocean, resolving sea-level slope discrepancy, improving tsunami warning system, ecology, etc., etc. The required instrumentation is not described here. The achieved as well as desired positional accuracy estimates in open ocean for various tasks are also given.
Computational solution of atmospheric chemistry problems
NASA Technical Reports Server (NTRS)
Jafri, J.; Ake, R. L.
1986-01-01
Extensive studies were performed on problems of interest in atmospheric chemistry. In addition to several minor projects, four major projects were performed and described (theoretical studies of ground and low-lying excited states of ClO2; ground and excited state potential energy surfaces of the methyl peroxy radical; electronic states ot the FO radical; and theoretical studies S02 (H2O) (sub n)).
Cosmic strings: A problem or a solution
Bennett, D.P.; Bouchet, F.R.
1987-10-01
The most fundamental issue in the theory of cosmic strings is addressed by means of Numerical Simulations: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, results are presented which, though still preliminary, offer the best support to date of this scaling hypothesis. 6 refs., 2 figs.
Some Problems of Heat Transfer in Rockets
1946-05-01
Pag« List of symbols ••••• rit Abstract • 1 Part I. INTRODUCTION 1 II. BEAT TRANSFER TO THE -..’ALLS OF THE BURSTER TUBE 3 III. EFFECT...fc. ,V2 2/t 1/8 Laplace operator, (J*0z*) t (daA9ys) t 0’/9z"). Thermal conductivity (cal/cm-sec-°C). Density of gas [ Part IZ] or density of TNT... Part IV] (gm/cm*). ^- (a’oA)D. •- (rj c/*)D. vUi SCME PROBLEMS OF BUT TRANSFER II ROCKETS Abstract Seme of the problem« ooanootod «1th tte
Bounding solutions of geometrically nonlinear viscoelastic problems
NASA Technical Reports Server (NTRS)
Stubstad, J. M.; Simitses, G. J.
1986-01-01
Integral transform techniques, such as the Laplace transform, provide simple and direct methods for solving viscoelastic problems formulated within a context of linear material response and using linear measures for deformation. Application of the transform operator reduces the governing linear integro-differential equations to a set of algebraic relations between the transforms of the unknown functions, the viscoelastic operators, and the initial and boundary conditions. Inversion either directly or through the use of the appropriate convolution theorem, provides the time domain response once the unknown functions have been expressed in terms of sums, products or ratios of known transforms. When exact inversion is not possible approximate techniques may provide accurate results. The overall problem becomes substantially more complex when nonlinear effects must be included. Situations where a linear material constitutive law can still be productively employed but where the magnitude of the resulting time dependent deformations warrants the use of a nonlinear kinematic analysis are considered. The governing equations will be nonlinear integro-differential equations for this class of problems. Thus traditional as well as approximate techniques, such as cited above, cannot be employed since the transform of a nonlinear function is not explicitly expressible.
Bounding solutions of geometrically nonlinear viscoelastic problems
NASA Technical Reports Server (NTRS)
Stubstad, J. M.; Simitses, G. J.
1985-01-01
Integral transform techniques, such as the Laplace transform, provide simple and direct methods for solving viscoelastic problems formulated within a context of linear material response and using linear measures for deformation. Application of the transform operator reduces the governing linear integro-differential equations to a set of algebraic relations between the transforms of the unknown functions, the viscoelastic operators, and the initial and boundary conditions. Inversion either directly or through the use of the appropriate convolution theorem, provides the time domain response once the unknown functions have been expressed in terms of sums, products or ratios of known transforms. When exact inversion is not possible approximate techniques may provide accurate results. The overall problem becomes substantially more complex when nonlinear effects must be included. Situations where a linear material constitutive law can still be productively employed but where the magnitude of the resulting time dependent deformations warrants the use of a nonlinear kinematic analysis are considered. The governing equations will be nonlinear integro-differential equations for this class of problems. Thus traditional as well as approximate techniques, such as cited above, cannot be employed since the transform of a nonlinear function is not explicitly expressible.
Finite-analytic numerical solution of heat transfer in two-dimensional cavity flow
NASA Technical Reports Server (NTRS)
Chen, C.-J.; Naseri-Neshat, H.; Ho, K.-S.
1981-01-01
Heat transfer in cavity flow is numerically analyzed by a new numerical method called the finite-analytic method. The basic idea of the finite-analytic method is the incorporation of local analytic solutions in the numerical solutions of linear or nonlinear partial differential equations. In the present investigation, the local analytic solutions for temperature, stream function, and vorticity distributions are derived. When the local analytic solution is evaluated at a given nodal point, it gives an algebraic relationship between a nodal value in a subregion and its neighboring nodal points. A system of algebraic equations is solved to provide the numerical solution of the problem. The finite-analytic method is used to solve heat transfer in the cavity flow at high Reynolds number (1000) for Prandtl numbers of 0.1, 1, and 10.
Finite Element Methods for Heat Transfer Problems.
1980-04-02
v are-c all positive are (1 +.( v) )6 + h(v1 -v1s)62 + .(lc-vld)63 = l k(c-w6 + (1 + l(v2 Mva +6 hf (v cv~ )63 = k(v3c-v 3 w)6 1 + hk(v 3c-v 3 s...is a three-level, explicit, central difference scheme. It has solutions of the form ’ k = k Xk xo ’ Pk PoX (16) where B4 X2_-1 2hX =0. (17) 2h X 2_
Radiative heat transfer as a Landauer-Büttiker problem
NASA Astrophysics Data System (ADS)
Yap, Han Hoe; Wang, Jian-Sheng
2017-01-01
We study the radiative heat transfer between two semi-infinite half-spaces, bounded by conductive surfaces in contact with vacuum. This setup is interpreted as a four-terminal mesoscopic transport problem. The slabs and interfaces are viewed as bosonic reservoirs, coupled perfectly to a scattering center consisting of the two planes and vacuum. Using Rytov's fluctuational electrodynamics and assuming Kirchhoff's circuital law, we calculate the heat flow in each bath. This allows for explicit evaluation of a conductance matrix, from which one readily verifies Büttiker symmetry. Thus, radiative heat transfer in layered media with conductive interfaces becomes a Landauer-Büttiker transport problem.
Simple Solutions for Space Station Audio Problems
NASA Technical Reports Server (NTRS)
Wood, Eric
2016-01-01
Throughout this summer, a number of different projects were supported relating to various NASA programs, including the International Space Station (ISS) and Orion. The primary project that was worked on was designing and testing an acoustic diverter which could be used on the ISS to increase sound pressure levels in Node 1, a module that does not have any Audio Terminal Units (ATUs) inside it. This acoustic diverter is not intended to be a permanent solution to providing audio to Node 1; it is simply intended to improve conditions while more permanent solutions are under development. One of the most exciting aspects of this project is that the acoustic diverter is designed to be 3D printed on the ISS, using the 3D printer that was set up earlier this year. Because of this, no new hardware needs to be sent up to the station, and no extensive hardware testing needs to be performed on the ground before sending it to the station. Instead, the 3D part file can simply be uploaded to the station's 3D printer, where the diverter will be made.
New high performance algorithmic solution for diagnosis problem
NASA Technical Reports Server (NTRS)
Fijany, Amir; Vatan, Farrokh
2005-01-01
In this paper we address the problem of generating the minimal diagnosis from the conflicts. This problem can be formulated as the well-known Hitting Set Problem. Our approach starts by mapping the Hitting Set problem into the Integer Programming Problem that enables us, for the first time, a priori determination of the lower and upper bounds on the size for the solution. Based on these bounds, we introduce a new concept of solution window for the problem. We also propose a new branch-and-bound technique that not only is faster than the current techniques in terms of number of operations (by exploiting the structure of the problem) but also, using the concept of window, allows a massive reduction (pruning) in the number of branches. Furthermore, as the branch-and-bound proceeds, the solution window is dynamically updated and narrowed to enable further pruning.
Integrated Learning Systems: The Problems with the Solution.
ERIC Educational Resources Information Center
Bentley, Edward
1991-01-01
Discusses problems with integrated learning systems (ILSs) in the schools, noting they are still an unproven solution to problems in education plagued by many serious limitations. The article recommends dealing with the fundamental problems of the educational system before investing time and money in ILS. (SM)
Skill Acquisition: Compilation of Weak-Method Problem Solutions.
ERIC Educational Resources Information Center
Anderson, John R.
According to the ACT theory of skill acquisition, cognitive skills are encoded by a set of productions, which are organized according to a hierarchical goal structure. People solve problems in new domains by applying weak problem-solving procedures to declarative knowledge they have about this domain. From these initial problem solutions,…
School Budgeting: Problems and Solutions. AASA Critical Issues Report.
ERIC Educational Resources Information Center
Hymes, Donald L.
School budget problems are discussed in 13 chapters, and solutions are suggested. Case studies present successful experiences with various problems while brief subsections summarize recommended actions. The first two chapters note that budget problems are worsening and trace the causes to tax revolts, state involvement in education, and the…
Numerical solution of large nonsymmetric eigenvalue problems
NASA Technical Reports Server (NTRS)
Saad, Youcef
1988-01-01
Several methods are discribed for combinations of Krylov subspace techniques, deflation procedures and preconditionings, for computing a small number of eigenvalues and eigenvectors or Schur vectors of large sparse matrices. The most effective techniques for solving realistic problems from applications are those methods based on some form of preconditioning and one of several Krylov subspace techniques, such as Arnoldi's method or Lanczos procedure. Two forms of preconditioning are considered: shift-and-invert and polynomial acceleration. The latter presents some advantages for parallel/vector processing but may be ineffective if eigenvalues inside the spectrum are sought. Some algorithmic details are provided that improve the reliability and effectiveness of these techniques.
High order accurate solutions of viscous problems
NASA Technical Reports Server (NTRS)
Hayder, M. E.; Turkel, Eli
1993-01-01
We consider a fourth order extension to MacCormack's scheme. The original extension was fourth order only for the inviscid terms but was second order for the viscous terms. We show how to modify the viscous terms so that the scheme is uniformly fourth order in the spatial derivatives. Applications are given to some boundary layer flows. In addition, for applications to shear flows the effect of the outflow boundary conditions are very important. We compare the accuracy of several of these different boundary conditions for both boundary layer and shear flows. Stretching at the outflow usually increases the oscillations in the numerical solution but the addition of a filtered sponge layer (with or without stretching) reduces such oscillations. The oscillations are generated by insufficient resolution of the shear layer. When the shear layer is sufficiently resolved then oscillations are not generated and there is less of a need for a nonreflecting boundary condition.
High order accurate solutions of viscous problems
NASA Technical Reports Server (NTRS)
Hayder, M. E.; Turkel, Eli
1993-01-01
We consider a fourth order extension to MacCormack's scheme. The original extension was fourth order only for the inviscid terms but was second order for the viscous terms. We show how to modify the viscous terms so that the scheme is uniformly fourth order in the spatial derivatives. Applications are given to some boundary layer flows. In addition, for applications to shear flows the effect of the outflow boundary conditions are very important. We compare the accuracy of several of these different boundary conditions for both boundary layer and shear flows. Stretching at the outflow usually increases the oscillations in the numerical solution but the addition of a filtered sponge layer (with or without stretching) reduces such oscillations. The oscillations are generated by insufficient resolution of the shear layer. When the shear layer is sufficiently resolved then oscillations are not generated and there is less of a need for a nonreflecting boundary condition.
Food sustainability: problems, perspectives and solutions.
Garnett, Tara
2013-02-01
The global food system makes a significant contribution to climate changing greenhouse gas emissions with all stages in the supply chain, from agricultural production through processing, distribution, retailing, home food preparation and waste, playing a part. It also gives rise to other major environmental impacts, including biodiversity loss and water extraction and pollution. Policy makers are increasingly aware of the need to address these concerns, but at the same time they are faced with a growing burden of food security and nutrition-related problems, and tasked with ensuring that there is enough food to meet the needs of a growing global population. In short, more people need to be fed better, with less environmental impact. How might this be achieved? Broadly, three main 'takes' or perspectives, on the issues and their interactions, appear to be emerging. Depending on one's view point, the problem can be conceptualised as a production challenge, in which case there is a need to change how food is produced by improving the unit efficiency of food production; a consumption challenge, which requires changes to the dietary drivers that determine food production; or a socio-economic challenge, which requires changes in how the food system is governed. This paper considers these perspectives in turn, their implications for nutrition and climate change, and their strengths and weaknesses. Finally, an argument is made for a reorientation of policy thinking which uses the insights provided by all three perspectives, rather than, as is the situation today, privileging one over the other.
The proton storage ring: Problems and solutions
Macek, R.J.
1988-01-01
The Los Alamos Proton Storage Ring (PSR) now operates with 35..mu..A at 20-Hz pulse repetition rate. Beam availability during 1988 suffered because of a number of problems with hardware reliability and from narrow operating margins for beam spill in the extraction line. A strong effort is underway to improve reliability with an eventual goal of obtaining beam availability in excess of 75%. Beam losses and the resulting component activation have limited operating currents to their present values. In detailed studies of the problem, loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two-step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. It is now apparent that the key to reducing losses is in reducing the number of foil traversals. A program of upgrades to reduce losses and improve the operating current is being planned. 8 refs., 17 figs., 2 tabs.
Boundary element solution for periodic acoustic problems
NASA Astrophysics Data System (ADS)
Karimi, M.; Croaker, P.; Kessissoglou, N.
2016-01-01
This work shows when using the boundary element method to solve 3D acoustic scattering problems from periodic structures, the coefficient matrix can be represented as a block Toeplitz matrix. By exploiting the Toeplitz structure, the computational time and storage requirements to construct the coefficient matrix are significantly reduced. To solve the linear system of equations, the original matrix is embedded into a larger and more structured matrix called the block circulant matrix. Discrete Fourier transform is then employed in an iterative algorithm to solve the block Toeplitz system. To demonstrate the effectiveness of the formulation for periodic acoustic problems, two exterior acoustic case studies are considered. The first case study examines a continuous structure to predict the noise generated by a sharp-edged flat plate under quadrupole excitation. Directivity plots obtained using the periodic boundary element method technique are compared with numerical results obtained using a conventional boundary element model. The second case study examines a discrete periodic structure to predict the acoustic performance of a sonic crystal noise barrier. Results for the barrier insertion loss are compared with both finite element results and available data in the literature.
Public problems: Still waiting on the marketplace for solutions
Gover, J.; Carayannis, E.; Huray, P.
1997-10-01
This report addresses the need for government sponsored R and D to address real public problems. The motivation is that a public benefit of the money spent must be demonstrated. The areas identified as not having appropriate attention resulting in unmet public needs include healthcare cost, cost and benefits of regulations, infrastructure problems, defense spending misaligned with foreign policy objectives, the crime problem, energy impact on the environment, the education problem, low productivity growth industry sectors, the income distribution problem, the aging problem, the propagation of disease and policy changes needed to address the solution of these problems.
Numerical solution of an inverse conductive boundary value problem
NASA Astrophysics Data System (ADS)
Yaman, F.
2008-12-01
In this paper, we derive a numerical solution of an inverse obstacle scattering problem with conductive boundary condition. The aim of the direct problem is the computation of the scattered field for a given arbitrarily shaped cylinder with conductive boundary condition on its surface.The inverse problem considered here is the reconstruction of the conductivity function of the scatterer from meausurements of the far field. A potential approach is used to obtain boundary layer integral equations both for the solution of the direct and the inverse problem. The numerical solutions of the integral equations which contain logarithmically singular kernels are evaluated by a Nyström method and Tikhonov regularization is used to solve the first kind of integral equations occuring in the solution of the inverse problem. Finally, numerical simulations are carried out to test the applicability and the effectiveness of the method.
Some Standard model problems and possible solutions
NASA Astrophysics Data System (ADS)
Barranco, J.
2016-10-01
Three problems of the standard model of elementary particles are studied from a phenomenological approach. (i) It is shown that the Dirac or the Majorana nature of the neutrino can be studied by looking for differences in the v-electron scattering if the polarization of the neutrino is considered. (ii) The absolute scale of the neutrino mass can be set if a four zero mass matrix texture is considered for the leptons. It is found that m ν3 ∼⃒ 0.05 eV. (iii) It is shown that it is possible -within a certain class of two Higgs model extensions of the standard model- to have a cancelation of the quadratic divergences to the mass of physical Higgs boson.
[Reprogramming of somatic cells. Problems and solutions].
Schneider, T A; Fishman, V S; Liskovykh, M A; Ponamartsev, S V; Serov, O L; Tomilin, A N; Alenina, N
2014-01-01
An adult mammal is composed of more than 200 different types of specialized somatic cells whose differentiated state remains stable over the life of the organism. For a long time it was believed that the differentiation process is irreversible, and the transition between the two types of specialized cells is impossible. The possibility of direct conversion of one differentiated cell type to another was first shown in the 80s of the last century in experiments on the conversion of fibroblasts into myoblasts by ectopic expression of the transcription factor MyoD. Surprisingly, this technology has remained unclaimed in cell biology for a long time. Interest in it revived after 200 thanks to the research of Novel Prize winner Shinya Yamanaka who has shown that a small set of transcription factors (Oct4, Sox2, Klf4 and c-Myc) is capable of restoring pluripotency in somatic cells which they lost in the process of differentiation. In 2010, using a similar strategy and the tissue-specific transcription factors Vierbuchen and coauthors showed the possibility of direct conversion of fibroblasts into neurons, i. e. the possibility of transdifferentiation of one type of somatic cells in the other. The works of these authoras were a breakthrough in the field of cell biology and gave a powerful impulse to the development of cell technologies for the needs of regenerative medicine. The present review discusses the main historical discoveries that preceded this work, evaluates the status of the problem and the progress in the development of methods for reprogramming at the moment, describes the main approaches to solving the problems of reprogramming of somatic cells into neuronal, and briefly discusses the prospect of application of reprogramming and transdifferentiation of cells for such important application areas as regenerative medicine, cell replacement therapy and drug screening.
Sensitivity Equation Derivation for Transient Heat Transfer Problems
NASA Technical Reports Server (NTRS)
Hou, Gene; Chien, Ta-Cheng; Sheen, Jeenson
2004-01-01
The focus of the paper is on the derivation of sensitivity equations for transient heat transfer problems modeled by different discretization processes. Two examples will be used in this study to facilitate the discussion. The first example is a coupled, transient heat transfer problem that simulates the press molding process in fabrication of composite laminates. These state equations are discretized into standard h-version finite elements and solved by a multiple step, predictor-corrector scheme. The sensitivity analysis results based upon the direct and adjoint variable approaches will be presented. The second example is a nonlinear transient heat transfer problem solved by a p-version time-discontinuous Galerkin's Method. The resulting matrix equation of the state equation is simply in the form of Ax = b, representing a single step, time marching scheme. A direct differentiation approach will be used to compute the thermal sensitivities of a sample 2D problem.
Chemicals in household products: problems with solutions.
Glegg, Gillian A; Richards, Jonathan P
2007-12-01
The success of a regulatory regime in decreasing point-source emissions of some harmful chemicals has highlighted the significance of other sources. A growing number of potentially harmful chemicals have been incorporated into an expanding range of domestic household products and are sold worldwide. Tighter regulation has been proposed, and the European Commission has introduced the Regulation on the Registration, Evaluation, and Authorisation of Chemicals to address this concern. However, it is clear that in addition to the regulation, there is a potential to effect change through retailer and consumer attitudes and behaviours. Interviews were conducted with 7 key stakeholder groups to identify critical issues, which were then explored using a public survey questionnaire (1,008 respondents) and 8 subsequent focus groups. The findings demonstrated that the issue of chemicals in products is of concern to consumers for reasons of personal health rather than environmental protection. Key obstacles to the wider purchase of "green-alternative" products included perceived high cost and poor performance, lack of availability of products, and poor information concerning such products. Although improved regulation was seen as part of the solution, consumers must also play a role. It was clear from this study that consumers are not currently able to make informed choices about the chemicals they use but that they would be receptive to moving toward a more sustainable use of chemicals in the future if empowered to do so.
[Typical problems in pediatric emergencies: Possible solutions].
Heimberg, E; Heinzel, O; Hoffmann, F
2015-06-01
Pediatric emergencies are rare and challenging for health care providers, parents, and patients. The purpose of this article is to highlight typical difficulties in the treatment of pediatric patients and to discuss potential solutions. This article is based on a selective literature search using PubMed and the experience of the authors in the field of simulation and pediatric emergencies. Inexperience with pediatric emergencies, uncertainty in technical skills, in the usage of pediatric equipment and in medication dosage as well as parental presence foster the perception of stress and potentially compromise the success of patient care. Beside implementation of simplified technical skill devices (e.g., intraosseous vascular access system, supraglottic airway devices, and alternative approaches for drug administration), there have been many efforts in recent years to improve patient safety. Tools for estimating body weight and precalculated drug-dosing charts have been implemented as well as standardized courses for guidelines, technical skills, and team-related skills have been established. To improve patient safety, regular training and implementation of a sustainable safety culture are mandatory.
[Solutions to problems in other countries].
Wendehorst, C
2000-12-01
The costs of public health in Germany are permanently increasing due to changes in the age-structure of the population, the development of new and expensive methods of medical treatment, the appearance of new diseases and other causes. There is a vivid discussion about how we could rationalize and/or restructure the public health system. In order to find solutions we should consider the provision of public health in other countries, for example in Sweden, Great Britain, the USA and Italy. Sweden has introduced a primary care system and fostered ambulatory care, with general practitioners and specialists working hand in hand in public health centres. In the USA costs have been reduced through the instruments of "Managed Care": global fees, global budgeting in hospital services, avoidance of hospitalization and efficiency checks. In Great Britain, medical care is centralized in the "National Health Service", which is paid out of the tax revenue. In Italy, there are local primary care centres, and secondary care is provided only on referral by a primary care physician. For drugs, a positive list has been introduced. Some of the instruments referred to could be implemented in Germany and help economize the provision of public health. However, the liberties of doctors and patients would probably be restricted.
A History of Aerospace Problems, Their Solutions, Their Lessons
NASA Technical Reports Server (NTRS)
Ryan, R. S.
1996-01-01
The positive aspect of problem occurrences is the opportunity for learning and a challenge for innovation. The learning aspect is not restricted to the solution period of the problem occurrence, but can become the beacon for problem prevention on future programs. Problems/failures serve as a point of departure for scaling to new designs. To ensure that problems/failures and their solutions guide the future programs, a concerted effort has been expended to study these problems, their solutions, their derived lessons learned, and projections for future programs. This includes identification of technology thrusts, process changes, codes development, etc. However, they must not become an excuse for adding layers upon layers of standards, criteria, and requirements, but must serve as guidelines that assist instead of stifling engineers. This report is an extension of prior efforts to accomplish this task. Although these efforts only scratch the surface, it is a beginning that others must complete.
Numerical solution of control problems governed by nonlinear differential equations
Heinkenschloss, M.
1994-12-31
In this presentation the author investigates an iterative method for the solution of optimal control problems. These problems are formulated as constrained optimization problems with constraints arising from the state equation and in the form of bound constraints on the control. The method for the solution of these problems uses the special structure of the problem arising from the bound constraint and the state equation. It is derived from SQP methods and projected Newton methods and combines the advantages of both methods. The bound constraint is satisfied by all iterates using a projection, the nonlinear state equation is satisfied in the limit. Only a linearized state equation has to be solved in every iteration. The solution of the linearized problems are done using multilevel methods and GMRES.
Problems and agricultural solutions in olive groves
NASA Astrophysics Data System (ADS)
Lozano-García, Beatriz; Parras-Alcántara, Luis
2017-04-01
The most important and extensive crops in the Mediterranean area are olive groves. Within the last 50 years, the surface occupied by olive groves has progressively increased in Spain including more complex topographies, poorer soils and worse climatic conditions. This situation has caused serious problems based on the losses of soil, nutrients and soil quality among others (Lozano-García and Parras-Alcántara, 2014). Therefore, alternative practices that avoid soil erosion and soil degradation must be considered. As a consequence, farmers together with scientist are innovating by the development of different practices in olive groves in order to avoid these problems and to improve soil conditions. There is a huge range of new practices. Some of them are: i. alternative management techniques such as organic farming, no tillage and minimum tillage. These techniques have a positive impact in soils (Parras-Alcántara and Lozano-García, 2014; Fernández-Romero et al., 2016). ii. the addition of different substances on the soil. For example, oil mill by-products that are thus potentially useful as soil amendments since they are effective sources of organic matter and nitrogen, improve soil quality and alleviate the environmental and agronomic limitations of Mediterranean agricultural soils, even those under using conventional tillage (Lozano-García et al., 2011; Lozano-García and Parras-Alcántara, 2013). iii. the use of covers as secondary crops inside the olive grove. These offer secondary benefits derived from alternative crops and soil protection due to fact that in olive groves the main problem is the high quantity of bare surface. With this contribution we want to show the current situation in olive groves and how better results could be obtained when both trustworthy information is available and farmers and scientist work together. REFERENCES Fernández-Romero, M.L., Parras-Alcántara, L., Lozano-García, B., Clark, J.M., Collins, C.D. 2016. Soil quality
Organ shortage crisis: problems and possible solutions.
Abouna, G M
2008-01-01
The demand for organ transplantation has rapidly increased all over the world during the past decade due to the increased incidence of vital organ failure, the rising success and greater improvement in posttransplant outcome. However, the unavailability of adequate organs for transplantation to meet the existing demand has resulted in major organ shortage crises. As a result there has been a major increase in the number of patients on transplant waiting lists as well as in the number of patients dying while on the waiting list. In the United States, for example, the number of patients on the waiting list in the year 2006 had risen to over 95,000, while the number of patient deaths was over 6,300. This organ shortage crisis has deprived thousands of patients of a new and better quality of life and has caused a substantial increase in the cost of alternative medical care such as dialysis. There are several procedures and pathways which have been shown to provide practical and effective solutions to this crisis. These include implementation of appropriate educational programs for the public and hospital staff regarding the need and benefits of organ donation, the appropriate utilization of marginal (extended criteria donors), acceptance of paired organ donation, the acceptance of the concept of "presumed consent," implementation of a system of "rewarded gifting" for the family of the diseased donor and also for the living donor, developing an altruistic system of donation from a living donor to an unknown recipient, and accepting the concept of a controlled system of financial payment for the donor. As is outlined in this presentation, we strongly believe that the implementation of these pathways for obtaining organs from the living and the dead donors, with appropriate consideration of the ethical, religious and social criteria of the society, the organ shortage crisis will be eliminated and many lives will be saved through the process of organ donation and
Solution of the Kirchhoff-Plateau Problem.
Giusteri, Giulio G; Lussardi, Luca; Fried, Eliot
2017-01-01
The Kirchhoff-Plateau problem concerns the equilibrium shapes of a system in which a flexible filament in the form of a closed loop is spanned by a liquid film, with the filament being modeled as a Kirchhoff rod and the action of the spanning surface being solely due to surface tension. We establish the existence of an equilibrium shape that minimizes the total energy of the system under the physical constraint of noninterpenetration of matter, but allowing for points on the surface of the bounding loop to come into contact. In our treatment, the bounding loop retains a finite cross-sectional thickness and a nonvanishing volume, while the liquid film is represented by a set with finite two-dimensional Hausdorff measure. Moreover, the region where the liquid film touches the surface of the bounding loop is not prescribed a priori. Our mathematical results substantiate the physical relevance of the chosen model. Indeed, no matter how strong is the competition between surface tension and the elastic response of the filament, the system is always able to adjust to achieve a configuration that complies with the physical constraints encountered in experiments.
Solution of the Kirchhoff-Plateau Problem
NASA Astrophysics Data System (ADS)
Giusteri, Giulio G.; Lussardi, Luca; Fried, Eliot
2017-06-01
The Kirchhoff-Plateau problem concerns the equilibrium shapes of a system in which a flexible filament in the form of a closed loop is spanned by a liquid film, with the filament being modeled as a Kirchhoff rod and the action of the spanning surface being solely due to surface tension. We establish the existence of an equilibrium shape that minimizes the total energy of the system under the physical constraint of noninterpenetration of matter, but allowing for points on the surface of the bounding loop to come into contact. In our treatment, the bounding loop retains a finite cross-sectional thickness and a nonvanishing volume, while the liquid film is represented by a set with finite two-dimensional Hausdorff measure. Moreover, the region where the liquid film touches the surface of the bounding loop is not prescribed a priori. Our mathematical results substantiate the physical relevance of the chosen model. Indeed, no matter how strong is the competition between surface tension and the elastic response of the filament, the system is always able to adjust to achieve a configuration that complies with the physical constraints encountered in experiments.
Solution to the Cosmic Ray Anisotropy Problem
NASA Astrophysics Data System (ADS)
Mertsch, Philipp; Funk, Stefan
2015-01-01
In the standard diffusive picture for transport of cosmic rays (CRs), a gradient in the CR density induces a typically small, dipolar anisotropy in their arrival directions. This is being widely advertised as a tool for finding nearby sources. However, the predicted dipole amplitude at TeV and PeV energies exceeds the measured one by almost 2 orders of magnitude. Here, we critically examine the validity of this prediction, which is based on averaging over an ensemble of turbulent magnetic fields. We focus on (1) the deviations of the dipole in a particular random realization from the ensemble average, and (2) the possibility of a misalignment between the regular magnetic field and the CR gradient. We find that if the field direction and the gradient direction are close to ˜90 ° , the dipole amplitude is considerably suppressed and can be reconciled with observations, which sheds light on a long-standing problem. Furthermore, we show that the dipole direction in general does not coincide with the gradient direction, thus hampering the search for nearby sources.
Solution of the Kirchhoff-Plateau Problem
NASA Astrophysics Data System (ADS)
Giusteri, Giulio G.; Lussardi, Luca; Fried, Eliot
2017-01-01
The Kirchhoff-Plateau problem concerns the equilibrium shapes of a system in which a flexible filament in the form of a closed loop is spanned by a liquid film, with the filament being modeled as a Kirchhoff rod and the action of the spanning surface being solely due to surface tension. We establish the existence of an equilibrium shape that minimizes the total energy of the system under the physical constraint of noninterpenetration of matter, but allowing for points on the surface of the bounding loop to come into contact. In our treatment, the bounding loop retains a finite cross-sectional thickness and a nonvanishing volume, while the liquid film is represented by a set with finite two-dimensional Hausdorff measure. Moreover, the region where the liquid film touches the surface of the bounding loop is not prescribed a priori. Our mathematical results substantiate the physical relevance of the chosen model. Indeed, no matter how strong is the competition between surface tension and the elastic response of the filament, the system is always able to adjust to achieve a configuration that complies with the physical constraints encountered in experiments.
Can false memories prime alternative solutions to ambiguous problems?
Howe, Mark L; Garner, Sarah R
2017-05-29
Research has demonstrated that false memories are capable of priming and facilitating insight-based problem-solving tasks by increasing solution rates and decreasing solution times. The present research extended this finding by investigating whether false memories could be used to bias ambiguous insight-based problem-solving tasks in a similar manner. Compound remote associate task (CRAT) problems with two possible correct answers, a dominant and a non-dominant solution, were created and normed (Experiment 1). In Experiment 2, participants were asked to solve these CRAT problems after they were given Deese/Roediger-McDermott lists whose critical lures were also the non-dominant solution to half of the corresponding CRATs. As predicted, when false memories served as primes, solution rates were higher and solution times were faster for non-dominant than dominant CRAT solutions. This biasing effect was only found when participants falsely recalled the critical lure, and was not found when participants did not falsely recall the critical lure, or when they were not primed. Results are discussed with regard to spreading activation models of solution competition in problem-solving tasks and current theories of false memory priming effects.
Moving to solution: effects of movement priming on problem solving.
Werner, K; Raab, M
2013-01-01
Embodied cognition theories suggest a link between bodily movements and cognitive functions. Given such a link, it is assumed that movement influences the two main stages of problem solving: creating a problem space and creating solutions. This study explores how specific the link between bodily movements and the problem-solving process is. Seventy-two participants were tested with variations of the two-string problem (Experiment 1) and the water-jar problem (Experiment 2), allowing for two possible solutions. In Experiment 1 participants were primed with arm-swing movements (swing group) and step movements on a chair (step group). In Experiment 2 participants sat in front of three jars with glass marbles and had to sort these marbles from the outer jars to the middle one (plus group) or vice versa (minus group). Results showed more swing-like solutions in the swing group and more step-like solutions in the step group, and more addition solutions in the plus group and more subtraction solutions in the minus group. This specificity of the connection between movement and problem-solving task will allow further experiments to investigate how bodily movements influence the stages of problem solving.
Vajravelu, K.; Kassab, A.; Hadjinicolaou, A.
1996-11-08
The nonlinear partial differential equations for the transient free convective heat transfer in a viscous, electrically conducting, and heat-generating fluid past a vertical porous plate in the presence of free stream oscillations are solved by the boundary element method (BEM). Time-dependent fundamental solutions are employed in a time marching scheme to resolve the field variables. Numerical results are compared with previously reported analytical solutions in order to validate the developed BEM algorithm. These previous studies reported results for simpler versions of the problem, in which the convective effects in the momentum and energy equations were neglected in order to obtain analytical numerical solutions. The BEM results are shown to be in close agreement with the reported data. The effects of convection currents, the temperature-dependent heat sources (or sinks), the magnetic currents, and the viscous dissipation on the flow and heat transfer characteristics are assessed in a parametric study, which considers a variety of the dimensionless parameters Gr, Ec, Pr, M, and {gamma}. It is observed that {gamma} plays an important role in delaying the fluid flow reversal, present in the case of air, and acts to enhance the effect of Gr in augmenting the rate of heat transfer at the wall. The skin friction is observed to be an increasing function of Gr, Ec, and {gamma} and a decreasing function of M and Pr. However, the rate of heat transfer (in an absolute sense) is an increasing function of M, {gamma}, Gr, and Ec and a decreasing function of Pr. Of all the parameters, the Prandtl number has the strongest effect on the flow and heat transfer characteristics.
Group Testing: Four Student Solutions to a Classic Optimization Problem
ERIC Educational Resources Information Center
Teague, Daniel
2006-01-01
This article describes several creative solutions developed by calculus and modeling students to the classic optimization problem of testing in groups to find a small number of individuals who test positive in a large population.
Hamilton's Principle and Approximate Solutions to Problems in Classical Mechanics
ERIC Educational Resources Information Center
Schlitt, D. W.
1977-01-01
Shows how to use the Ritz method for obtaining approximate solutions to problems expressed in variational form directly from the variational equation. Application of this method to classical mechanics is given. (MLH)
Hamilton's Principle and Approximate Solutions to Problems in Classical Mechanics
ERIC Educational Resources Information Center
Schlitt, D. W.
1977-01-01
Shows how to use the Ritz method for obtaining approximate solutions to problems expressed in variational form directly from the variational equation. Application of this method to classical mechanics is given. (MLH)
Models and Solution for On-Demand Data Delivery Problems
1999-01-01
servers. We will describe motivation and format of the basic model, and several enhancements to the model formulation and solution process that are necessary to solve the problem within reasonable time limits.
The Reasons and Solutions for Problems in Rural School Consolidation
ERIC Educational Resources Information Center
Qingyang, Guo
2013-01-01
Based on investigations in six midwestern provinces/autonomous regions, Hubei, Henan, Guangxi, Yunnan, Shaanxi, and Inner Mongolia, this article analyzes the reasons for problems in the process of consolidating rural schools and their solutions.
Algebraic solution of the synthesis problem for coded sequences
Leukhin, Anatolii N
2005-08-31
The algebraic solution of a 'complex' problem of synthesis of phase-coded (PC) sequences with the zero level of side lobes of the cyclic autocorrelation function (ACF) is proposed. It is shown that the solution of the synthesis problem is connected with the existence of difference sets for a given code dimension. The problem of estimating the number of possible code combinations for a given code dimension is solved. It is pointed out that the problem of synthesis of PC sequences is related to the fundamental problems of discrete mathematics and, first of all, to a number of combinatorial problems, which can be solved, as the number factorisation problem, by algebraic methods by using the theory of Galois fields and groups. (fourth seminar to the memory of d.n. klyshko)
Spectral solution of the viscous blunt-body problem
NASA Technical Reports Server (NTRS)
Kopriva, David A.
1993-01-01
The viscous blunt-body problem is solved with a shock-fitted Chebyshev spectral method. No explicit artificial viscosity or filtering is needed to obtain smooth, converged solutions. The method is applied to two problems. First, results for the flow over a right circular cylinder in the Mach number range of 5.5-6.0 are compared with experimental data. Second, a solution for a Mach 25 flow over a hyperbolic cone is compared with a viscous shock-layer calculation.
On three dimensional magnetic inverse problems solution for stellar bodies
NASA Astrophysics Data System (ADS)
Martyshko, Petr S.; Martyshko, Maxim P.
2017-07-01
The new 3D magnetic inverse problem equations for stellar bodies have been derived (of interior and outside fields). We take into account demagnetization factor. Due to choice of special parametric set we have suggested stable algorithm for equations solving. Based on these equations it is possible to use method which does not require trial-and-error forward modeling and allows us to construct inverse problem solutions. Using borehole data we can determine the unique solution.
Parallel decomposition methods for the solution of electromagnetic scattering problems
NASA Technical Reports Server (NTRS)
Cwik, Tom
1992-01-01
This paper contains a overview of the methods used in decomposing solutions to scattering problems onto coarse-grained parallel processors. Initially, a short summary of relevant computer architecture is presented as background to the subsequent discussion. After the introduction of a programming model for problem decomposition, specific decompositions of finite difference time domain, finite element, and integral equation solutions to Maxwell's equations are presented. The paper concludes with an outline of possible software-assisted decomposition methods and a summary.
Inverse heat conduction problem in a phase change memory device
NASA Astrophysics Data System (ADS)
Battaglia, Jean-Luc; De, Indrayush; Sousa, Véronique
2017-01-01
An invers heat conduction problem is solved considering the thermal investigation of a phase change memory device using the scanning thermal microscopy. The heat transfer model rests on system identification for the probe thermal impedance and on a finite element method for the device thermal impedance. Unknown parameters in the model are then identified using a nonlinear least square algorithm that minimizes the quadratic gap between the measured probe temperature and the simulated one.
Approximated analytical solution to an Ebola optimal control problem
NASA Astrophysics Data System (ADS)
Hincapié-Palacio, Doracelly; Ospina, Juan; Torres, Delfim F. M.
2016-11-01
An analytical expression for the optimal control of an Ebola problem is obtained. The analytical solution is found as a first-order approximation to the Pontryagin Maximum Principle via the Euler-Lagrange equation. An implementation of the method is given using the computer algebra system Maple. Our analytical solutions confirm the results recently reported in the literature using numerical methods.
General Solution of the Kenamond HE Problem 3
Kaul, Ann
2015-12-15
A general solution for programmed burn calculations of the light times produced by a singlepoint initiation of a single HE region surrounding an inert region has been developed. In contrast to the original solutions proposed in References 1 and 2, the detonator is no longer restricted to a location on a Cartesian axis and can be located at any point inside the HE region. This general solution has been implemented in the ExactPack suite of exact solvers for verification problems.
Constructing high-pressure thermodynamic models: problems and possible solutions
NASA Astrophysics Data System (ADS)
Brosh, E.
2013-12-01
Conventional thermodynamic databases (e.g. Fabrichnaya et al. 2004, Holland and Powell 1998, 2011) consist of expressions for the Gibbs energy at ambient pressure, extended to higher pressures through the integration of some EOS (Equation Of State). While this is simple and straight-forward, such thermodynamic models are prone to produce manifestly unphysical predictions of negative thermal expansion and even negative heat capacity at high pressure. It has been shown (Brosh et al. 2007) that these errors arise not only from problems the EOS itself but also from incompatibilities between the EOS and the models used for extrapolations of the heat capacity at ambient pressure. One solution is a radical restructuring of thermodynamic databases. Instead of modelling the Gibbs energy, new databases can be based on modelling the Helmholtz energy using Debye-Mie-Grüneisen EOS. This approach is very successful for modelling solid substances (Jacobs 2009, 2010, Dorogokupets et al. 2007, 2012) but the Debye-Mie-Grüneisen equations of state are not easily applicable to liquids. Other difficulties stem from the treatment of the predicted mechanical instability above the normal melting point. However, the most severe difficulty with the utilization of the Debye-Mie-Grüneisen approach is that it is incompatible with the current ambient-pressure thermodynamic databases and one will not be able to use them as a basis for high pressure modelling. Another approach (Brosh et al. 2007) is based on an interpolation of the thermophysical properties between the ambient pressure models given in conventional databases and the Debye-Mie-Grüneisen model at extreme pressures. This avoids most of the spurious anomalies of conventional models. The limitations of the interpolation scheme are the inclusion of several model parameters whose physical essence is not well-defined and an underestimation of the heat capacity at high pressures. In this presentation, the predictions of the
[Vulnerability to environmental heat among persons with mental health problems].
Vida, Stephen
2011-01-01
This review is intended to alert health professionals to the particular vulnerability of persons with mental health problems or taking certain medications to heat-related illness, a threat that is increasing due to climate change. It reviews epidemiology, physiology and clinical features of heat-related illness. For acute medical management, it refers readers to existing guidelines and recommendations. It reviews risk and protective factors. Finally, it presents preventive strategies that may help reduce the impact of heat-related illness in this population.
Doebling, Scott William
2016-10-22
This paper documents the escape of high explosive (HE) products problem. The problem, first presented by Fickett & Rivard, tests the implementation and numerical behavior of a high explosive detonation and energy release model and its interaction with an associated compressible hydrodynamics simulation code. The problem simulates the detonation of a finite-length, one-dimensional piece of HE that is driven by a piston from one end and adjacent to a void at the other end. The HE equation of state is modeled as a polytropic ideal gas. The HE detonation is assumed to be instantaneous with an infinitesimal reaction zone. Via judicious selection of the material specific heat ratio, the problem has an exact solution with linear characteristics, enabling a straightforward calculation of the physical variables as a function of time and space. Lastly, implementation of the exact solution in the Python code ExactPack is discussed, as are verification cases for the exact solution code.
Leak testing of cryogenic components — problems and solutions
NASA Astrophysics Data System (ADS)
Srivastava, S. P.; Pandarkar, S. P.; Unni, T. G.; Sinha, A. K.; Mahajan, K.; Suthar, R. L.
2008-05-01
moderator pot was driving the MSLD out of range. Since it was very difficult to locate the leak by Tracer Probe Method, some other technique was ventured to solve the problem of leak location. Finally, it was possible to locate the leak by observing the change in Helium background reading of MSLD during masking/unmasking of the welded joints. This paper, in general describes the design and leak testing aspects of cryogenic components of Cold Neutron Source and in particular, the problems and solutions for leak testing of transfer lines and moderator pot.
Possible solution of strong CP problem in generalized unimodular gravity
Frampton, P.H.; Ng, Y.J.; Van Dam, H. )
1992-11-01
It was recently pointed out how constrained gravitational dynamics offers a possible solution of the cosmological constant problem at the quantum level. Here we point out that the same theory may be used to solve the strong CP problem without recourse to wormholes or to the introduction of any new particle.
Error estimates of numerical solutions for a cyclic plasticity problem
NASA Astrophysics Data System (ADS)
Han, W.
A cyclic plasticity problem is numerically analyzed in [13], where a sub-optimal order error estimate is shown for a spatially discrete scheme. In this note, we prove an optimal order error estimate for the spatially discrete scheme under the same solution regularity condition. We also derive an error estimate for a fully discrete scheme for solving the plasticity problem.
Fast multigrid solution of the advection problem with closed characteristics
Yavneh, I.; Venner, C.H.; Brandt, A.
1996-12-31
The numerical solution of the advection-diffusion problem in the inviscid limit with closed characteristics is studied as a prelude to an efficient high Reynolds-number flow solver. It is demonstrated by a heuristic analysis and numerical calculations that using upstream discretization with downstream relaxation-ordering and appropriate residual weighting in a simple multigrid V cycle produces an efficient solution process. We also derive upstream finite-difference approximations to the advection operator, whose truncation terms approximate {open_quotes}physical{close_quotes} (Laplacian) viscosity, thus avoiding spurious solutions to the homogeneous problem when the artificial diffusivity dominates the physical viscosity.
Solution of the stochastic control problem in unbounded domains.
NASA Technical Reports Server (NTRS)
Robinson, P.; Moore, J.
1973-01-01
Bellman's dynamic programming equation for the optimal index and control law for stochastic control problems is a parabolic or elliptic partial differential equation frequently defined in an unbounded domain. Existing methods of solution require bounded domain approximations, the application of singular perturbation techniques or Monte Carlo simulation procedures. In this paper, using the fact that Poisson impulse noise tends to a Gaussian process under certain limiting conditions, a method which achieves an arbitrarily good approximate solution to the stochastic control problem is given. The method uses the two iterative techniques of successive approximation and quasi-linearization and is inherently more efficient than existing methods of solution.
Solution of second order quasi-linear boundary value problems by a wavelet method
Zhang, Lei; Zhou, Youhe; Wang, Jizeng
2015-03-10
A wavelet Galerkin method based on expansions of Coiflet-like scaling function bases is applied to solve second order quasi-linear boundary value problems which represent a class of typical nonlinear differential equations. Two types of typical engineering problems are selected as test examples: one is about nonlinear heat conduction and the other is on bending of elastic beams. Numerical results are obtained by the proposed wavelet method. Through comparing to relevant analytical solutions as well as solutions obtained by other methods, we find that the method shows better efficiency and accuracy than several others, and the rate of convergence can even reach orders of 5.8.
Solution of acoustic workshop problems by a spectral multidomain method
NASA Technical Reports Server (NTRS)
Kopriva, Davis A.; Kolias, John H.
1995-01-01
We use a new staggered grid Chebyshev spectral multidomain method to solve three of the Workshop benchmark problems. The method defines solution unknowns at the nodes of the Chebyshev Gauss quadrature, and the fluxes at the nodes of the Chebyshev Gauss-Lobatto quadrature. The Chebyshev spectral method gives exponentially convergent phase and dissipation errors. The multidomain approximation gives the method flexibility. Using the method, we solve problems in Categories 1 and 5 of the benchmark problems.
Cathodic protection of offshore structures - Problems and solutions
Robson, D.N.C.
1985-01-01
The paper outlines the three basic options for cathodically protecting offshore structures; namely impressed current or sacrificial anodes protecting a bare metal structure or sacrificial anodes on a totally painted structure. Some of the problems encountered by these systems are described and some specific examples experienced by Britiol structures are discussed in more detail. Various solutions for overcoming these problems are discussed and comparisons made of their respective costs and ease of implementation. Finally, some solution to CP problems adopted by Britoil are described with emphasis on the difficulties in implementation.
Entrepreneurship--transforming a perioperative problem into a product solution.
Hoftman, M
1999-09-01
No one is more capable of identifying problems related to health care than health care practitioners. Identifying a problem is the first step to every new product or invention. This article provides step-by-step information to help health care practitioners identify problems and possible solutions, look for a creative company to bring the solution to the marketplace, and present the product idea to potential industry partners. The author also discusses the legal aspects of product development and the advantages and disadvantages of licensing a new product or starting a business to develop a product.
Unbounded Periodic Solutions to Serrin's Overdetermined Boundary Value Problem
NASA Astrophysics Data System (ADS)
Fall, Mouhamed Moustapha; Minlend, Ignace Aristide; Weth, Tobias
2017-02-01
We study the existence of nontrivial unbounded domains {Ω} in RN such that the overdetermined problem {-Δ u = 1 quad in Ω}, quad u = 0, quad partial_{ν} u = const quad on partial Ω admits a solution u. By this, we complement Serrin's classification result from 1971, which yields that every bounded domain admitting a solution of the above problem is a ball in RN. The domains we construct are periodic in some variables and radial in the other variables, and they bifurcate from a straight (generalized) cylinder or slab. We also show that these domains are uniquely self Cheeger relative to a period cell for the problem.
One dimensional global and local solution for ICRF heating
Wang, C.Y.; Batchelor, D.B.; Jaeger, E.F.; Carter, M.D.
1995-02-01
A numerical code GLOSI [Global and Local One-dimensional Solution for Ion cyclotron range of frequencies (ICRF) heating] is developed to solve one-dimensional wave equations resulting from the use of radio frequency (RF) waves to heat plasmas. The code uses a finite difference method. Due to its numerical stability, the code can be used to find both global and local solutions when imposed with appropriate boundary conditions. Three types of boundary conditions are introduced to describe wave scattering, antenna wave excitation, and fixed tangential wave magnetic field. The scattering boundary conditions are especially useful for local solutions. The antenna wave excitation boundary conditions can be used to excite fast and slow waves in a plasma. The tangential magnetic field boundary conditions are used to calculate impedance matrices, which describe plasma and antenna coupling and can be used by an antenna code to calculate antenna loading. These three types of boundary conditions can also be combined to describe various physical situations in RF plasma heating. The code also includes plasma thermal effects and calculates collisionless power absorption and kinetic energy flux. The plasma current density is approximated by a second-order Larmor radius expansion, which results in a sixth-order ordinary differential equation.
Heat Transfer Characterization Using Heat and Solute Tracer Tests in a Shallow Alluvial Aquifer
NASA Astrophysics Data System (ADS)
Dassargues, A.
2013-12-01
Very low enthalpy geothermal systems are increasingly considered for heating or cooling using groundwater energy combined with heat pumps. The design and the impact of shallow geothermal systems are often assessed in a semi-empirical way. It is accepted by most of the private partners but not by environmental authorities deploring a lack of rigorous evaluation of the mid- to long-term impact on groundwater. In view of a more rigorous methodology, heat and dye tracers are used for estimating simultaneously heat transfer and solute transport parameters in an alluvial aquifer. The experimental field site, is equipped with 21 piezometers drilled in alluvial deposits composed of a loam layer overlying a sand and gravel layer constituting the alluvial aquifer. The tracing experiment consisted in injecting simultaneously heated water and a dye tracer in a piezometer and monitoring evolution of groundwater temperature and tracer concentration in 3 control panels set perpendicularly to the main groundwater flow. Results showed drastic differences between heat transfer and solute transport due to the main influence of thermal capacity of the saturated porous medium. The tracing experiment was then simulated using a numerical model and the best estimation of heat transfer and solute transport parameters is obtained by calibrating this numerical model using inversion tools. The developed concepts and tests may lead to real projects of various extents that can be now optimized by the use of a rigorous and efficient methodology at the field scale. On the field: view from the injection well in direction of the pumping well through the three monitoring panels Temperature monitoring in the pumping well and in the piezometers of the three panels: heat transfer is faster in the lower part of the aquifer (blue curves) than in the upper part (red curves). Breakthrough curves are also more dispersed in the upper part with longer tailings.
Fuzzy α-minimum spanning tree problem: definition and solutions
NASA Astrophysics Data System (ADS)
Zhou, Jian; Chen, Lu; Wang, Ke; Yang, Fan
2016-04-01
In this paper, the minimum spanning tree problem is investigated on the graph with fuzzy edge weights. The notion of fuzzy ? -minimum spanning tree is presented based on the credibility measure, and then the solutions of the fuzzy ? -minimum spanning tree problem are discussed under different assumptions. First, we respectively, assume that all the edge weights are triangular fuzzy numbers and trapezoidal fuzzy numbers and prove that the fuzzy ? -minimum spanning tree problem can be transformed to a classical problem on a crisp graph in these two cases, which can be solved by classical algorithms such as the Kruskal algorithm and the Prim algorithm in polynomial time. Subsequently, as for the case that the edge weights are general fuzzy numbers, a fuzzy simulation-based genetic algorithm using Prüfer number representation is designed for solving the fuzzy ? -minimum spanning tree problem. Some numerical examples are also provided for illustrating the effectiveness of the proposed solutions.
Solution procedure of dynamical contact problems with friction
NASA Astrophysics Data System (ADS)
Abdelhakim, Lotfi
2017-07-01
Dynamical contact is one of the common research topics because of its wide applications in the engineering field. The main goal of this work is to develop a time-stepping algorithm for dynamic contact problems. We propose a finite element approach for elastodynamics contact problems [1]. Sticking, sliding and frictional contact can be taken into account. Lagrange multipliers are used to enforce non-penetration condition. For the time discretization, we propose a scheme equivalent to the explicit Newmark scheme. Each time step requires solving a nonlinear problem similar to a static friction problem. The nonlinearity of the system of equation needs an iterative solution procedure based on Uzawa's algorithm [2][3]. The applicability of the algorithm is illustrated by selected sample numerical solutions to static and dynamic contact problems. Results obtained with the model have been compared and verified with results from an independent numerical method.
Exact solution for the optimal neuronal layout problem.
Chklovskii, Dmitri B
2004-10-01
Evolution perfected brain design by maximizing its functionality while minimizing costs associated with building and maintaining it. Assumption that brain functionality is specified by neuronal connectivity, implemented by costly biological wiring, leads to the following optimal design problem. For a given neuronal connectivity, find a spatial layout of neurons that minimizes the wiring cost. Unfortunately, this problem is difficult to solve because the number of possible layouts is often astronomically large. We argue that the wiring cost may scale as wire length squared, reducing the optimal layout problem to a constrained minimization of a quadratic form. For biologically plausible constraints, this problem has exact analytical solutions, which give reasonable approximations to actual layouts in the brain. These solutions make the inverse problem of inferring neuronal connectivity from neuronal layout more tractable.
Explicit solutions of a gravity-induced film flow along a convectively heated vertical wall.
Raees, Ammarah; Xu, Hang
2013-01-01
The gravity-driven film flow has been analyzed along a vertical wall subjected to a convective boundary condition. The Boussinesq approximation is applied to simplify the buoyancy term, and similarity transformations are used on the mathematical model of the problem under consideration, to obtain a set of coupled ordinary differential equations. Then the reduced equations are solved explicitly by using homotopy analysis method (HAM). The resulting solutions are investigated for heat transfer effects on velocity and temperature profiles.
Explicit Solutions of a Gravity-Induced Film Flow along a Convectively Heated Vertical Wall
Raees, Ammarah
2013-01-01
The gravity-driven film flow has been analyzed along a vertical wall subjected to a convective boundary condition. The Boussinesq approximation is applied to simplify the buoyancy term, and similarity transformations are used on the mathematical model of the problem under consideration, to obtain a set of coupled ordinary differential equations. Then the reduced equations are solved explicitly by using homotopy analysis method (HAM). The resulting solutions are investigated for heat transfer effects on velocity and temperature profiles. PMID:24453862
Numerical solutions of acoustic wave propagation problems using Euler computations
NASA Technical Reports Server (NTRS)
Hariharan, S. I.
1984-01-01
This paper reports solution procedures for problems arising from the study of engine inlet wave propagation. The first problem is the study of sound waves radiated from cylindrical inlets. The second one is a quasi-one-dimensional problem to study the effect of nonlinearities and the third one is the study of nonlinearities in two dimensions. In all three problems Euler computations are done with a fourth-order explicit scheme. For the first problem results are shown in agreement with experimental data and for the second problem comparisons are made with an existing asymptotic theory. The third problem is part of an ongoing work and preliminary results are presented for this case.
Polynomial Eigenvalue Solutions to Minimal Problems in Computer Vision.
Kukelova, Zuzana; Bujnak, Martin; Pajdla, Tomas
2012-07-01
We present a method for solving systems of polynomial equations appearing in computer vision. This method is based on polynomial eigenvalue solvers and is more straightforward and easier to implement than the state-of-the-art Gröbner basis method since eigenvalue problems are well studied, easy to understand, and efficient and robust algorithms for solving these problems are available. We provide a characterization of problems that can be efficiently solved as polynomial eigenvalue problems (PEPs) and present a resultant-based method for transforming a system of polynomial equations to a polynomial eigenvalue problem. We propose techniques that can be used to reduce the size of the computed polynomial eigenvalue problems. To show the applicability of the proposed polynomial eigenvalue method, we present the polynomial eigenvalue solutions to several important minimal relative pose problems.
THERM3D -- A boundary element computer program for transient heat conduction problems
Ingber, M.S.
1994-02-01
The computer code THERM3D implements the direct boundary element method (BEM) to solve transient heat conduction problems in arbitrary three-dimensional domains. This particular implementation of the BEM avoids performing time-consuming domain integrations by approximating a ``generalized forcing function`` in the interior of the domain with the use of radial basis functions. An approximate particular solution is then constructed, and the original problem is transformed into a sequence of Laplace problems. The code is capable of handling a large variety of boundary conditions including isothermal, specified flux, convection, radiation, and combined convection and radiation conditions. The computer code is benchmarked by comparisons with analytic and finite element results.
Parallel solution of sparse one-dimensional dynamic programming problems
NASA Technical Reports Server (NTRS)
Nicol, David M.
1989-01-01
Parallel computation offers the potential for quickly solving large computational problems. However, it is often a non-trivial task to effectively use parallel computers. Solution methods must sometimes be reformulated to exploit parallelism; the reformulations are often more complex than their slower serial counterparts. We illustrate these points by studying the parallelization of sparse one-dimensional dynamic programming problems, those which do not obviously admit substantial parallelization. We propose a new method for parallelizing such problems, develop analytic models which help us to identify problems which parallelize well, and compare the performance of our algorithm with existing algorithms on a multiprocessor.
Adjoint optimization of natural convection problems: differentially heated cavity
NASA Astrophysics Data System (ADS)
Saglietti, Clio; Schlatter, Philipp; Monokrousos, Antonios; Henningson, Dan S.
2016-06-01
Optimization of natural convection-driven flows may provide significant improvements to the performance of cooling devices, but a theoretical investigation of such flows has been rarely done. The present paper illustrates an efficient gradient-based optimization method for analyzing such systems. We consider numerically the natural convection-driven flow in a differentially heated cavity with three Prandtl numbers (Pr=0.15{-}7 ) at super-critical conditions. All results and implementations were done with the spectral element code Nek5000. The flow is analyzed using linear direct and adjoint computations about a nonlinear base flow, extracting in particular optimal initial conditions using power iteration and the solution of the full adjoint direct eigenproblem. The cost function for both temperature and velocity is based on the kinetic energy and the concept of entransy, which yields a quadratic functional. Results are presented as a function of Prandtl number, time horizons and weights between kinetic energy and entransy. In particular, it is shown that the maximum transient growth is achieved at time horizons on the order of 5 time units for all cases, whereas for larger time horizons the adjoint mode is recovered as optimal initial condition. For smaller time horizons, the influence of the weights leads either to a concentric temperature distribution or to an initial condition pattern that opposes the mean shear and grows according to the Orr mechanism. For specific cases, it could also been shown that the computation of optimal initial conditions leads to a degenerate problem, with a potential loss of symmetry. In these situations, it turns out that any initial condition lying in a specific span of the eigenfunctions will yield exactly the same transient amplification. As a consequence, the power iteration converges very slowly and fails to extract all possible optimal initial conditions. According to the authors' knowledge, this behavior is illustrated here
Analytic solution for heat flow through a general harmonic network.
Freitas, Nahuel; Paz, Juan Pablo
2014-10-01
We present an analytic expression for the heat current through a general harmonic network coupled with Ohmic reservoirs. We use a method that enables us to express the stationary state of the network in terms of the eigenvectors and eigenvalues of a generalized cubic eigenvalue problem. In this way, we obtain exact formulas for the heat current and the local temperature inside the network. Our method does not rely on the usual assumptions of weak coupling to the environments or on the existence of an infinite cutoff in the environmental spectral densities. We use this method to study nonequilibrium processes without the weak coupling and Markovian approximations. As a first application of our method, we revisit the problem of heat conduction in two- and three-dimensional crystals with binary mass disorder. We complement previous results showing that for small systems the scaling of the heat current with the system size greatly depends on the strength of the interaction between system and reservoirs. This somewhat counterintuitive result seems not to have been noticed before.
Analytic solution for heat flow through a general harmonic network
NASA Astrophysics Data System (ADS)
Freitas, Nahuel; Paz, Juan Pablo
2014-10-01
We present an analytic expression for the heat current through a general harmonic network coupled with Ohmic reservoirs. We use a method that enables us to express the stationary state of the network in terms of the eigenvectors and eigenvalues of a generalized cubic eigenvalue problem. In this way, we obtain exact formulas for the heat current and the local temperature inside the network. Our method does not rely on the usual assumptions of weak coupling to the environments or on the existence of an infinite cutoff in the environmental spectral densities. We use this method to study nonequilibrium processes without the weak coupling and Markovian approximations. As a first application of our method, we revisit the problem of heat conduction in two- and three-dimensional crystals with binary mass disorder. We complement previous results showing that for small systems the scaling of the heat current with the system size greatly depends on the strength of the interaction between system and reservoirs. This somewhat counterintuitive result seems not to have been noticed before.
NASA Technical Reports Server (NTRS)
Tamma, Kumar K.; D'Costa, Joseph F.
1991-01-01
This paper describes the evaluation of mixed implicit-explicit finite element formulations for hyperbolic heat conduction problems involving non-Fourier effects. In particular, mixed implicit-explicit formulations employing the alpha method proposed by Hughes et al. (1987, 1990) are described for the numerical simulation of hyperbolic heat conduction models, which involves time-dependent relaxation effects. Existing analytical approaches for modeling/analysis of such models involve complex mathematical formulations for obtaining closed-form solutions, while in certain numerical formulations the difficulties include severe oscillatory solution behavior (which often disguises the true response) in the vicinity of the thermal disturbances, which propagate with finite velocities. In view of these factors, the alpha method is evaluated to assess the control of the amount of numerical dissipation for predicting the transient propagating thermal disturbances. Numerical test models are presented, and pertinent conclusions are drawn for the mixed-time integration simulation of hyperbolic heat conduction models involving non-Fourier effects.
A new solution for maximal clique problem based sticker model.
Darehmiraki, Majid
2009-02-01
In this paper, we use stickers to construct a solution space of DNA for the maximal clique problem (MCP). Simultaneously, we also apply the DNA operation in the sticker-based model to develop a DNA algorithm. The results of the proposed algorithm show that the MCP is resolved with biological operations in the sticker-based model for the solution space of the sticker. Moreover, this work presents clear evidence of the ability of DNA computing to solve the NP-complete problem. The potential of DNA computing for the MCP is promising given the operational time complexity of O(nxk).
Elementary Solution to the Time-Independent Quantum Navigation Problem
NASA Astrophysics Data System (ADS)
Brody, Dorje C.; Meier, David M.
2015-02-01
A quantum navigation problem concerns the identification of a time-optimal Hamiltonian that realizes a required quantum process or task, under the influence of a prevailing ‘background’ Hamiltonian that cannot be manipulated. When the task is to transform one quantum state into another, finding the solution in closed form to the problem is nontrivial even in the case of time-independent Hamiltonians. An elementary solution, based on trigonometric analysis, is found here when the Hilbert space dimension is two. Difficulties arising from generalizations to higher-dimensional systems are discussed.
Application of Genetic Algorithms in Nonlinear Heat Conduction Problems
Khan, Waqar A.
2014-01-01
Genetic algorithms are employed to optimize dimensionless temperature in nonlinear heat conduction problems. Three common geometries are selected for the analysis and the concept of minimum entropy generation is used to determine the optimum temperatures under the same constraints. The thermal conductivity is assumed to vary linearly with temperature while internal heat generation is assumed to be uniform. The dimensionless governing equations are obtained for each selected geometry and the dimensionless temperature distributions are obtained using MATLAB. It is observed that GA gives the minimum dimensionless temperature in each selected geometry. PMID:24695517
Application of genetic algorithms in nonlinear heat conduction problems.
Kadri, Muhammad Bilal; Khan, Waqar A
2014-01-01
Genetic algorithms are employed to optimize dimensionless temperature in nonlinear heat conduction problems. Three common geometries are selected for the analysis and the concept of minimum entropy generation is used to determine the optimum temperatures under the same constraints. The thermal conductivity is assumed to vary linearly with temperature while internal heat generation is assumed to be uniform. The dimensionless governing equations are obtained for each selected geometry and the dimensionless temperature distributions are obtained using MATLAB. It is observed that GA gives the minimum dimensionless temperature in each selected geometry.
Solution of the determinantal assignment problem using the Grassmann matrices
NASA Astrophysics Data System (ADS)
Karcanias, Nicos; Leventides, John
2016-02-01
The paper provides a direct solution to the determinantal assignment problem (DAP) which unifies all frequency assignment problems of the linear control theory. The current approach is based on the solvability of the exterior equation ? where ? is an n -dimensional vector space over ? which is an integral part of the solution of DAP. New criteria for existence of solution and their computation based on the properties of structured matrices are referred to as Grassmann matrices. The solvability of this exterior equation is referred to as decomposability of ?, and it is in turn characterised by the set of quadratic Plücker relations (QPRs) describing the Grassmann variety of the corresponding projective space. Alternative new tests for decomposability of the multi-vector ? are given in terms of the rank properties of the Grassmann matrix, ? of the vector ?, which is constructed by the coordinates of ?. It is shown that the exterior equation is solvable (? is decomposable), if and only if ? where ?; the solution space for a decomposable ?, is the space ?. This provides an alternative linear algebra characterisation of the decomposability problem and of the Grassmann variety to that defined by the QPRs. Further properties of the Grassmann matrices are explored by defining the Hodge-Grassmann matrix as the dual of the Grassmann matrix. The connections of the Hodge-Grassmann matrix to the solution of exterior equations are examined, and an alternative new characterisation of decomposability is given in terms of the dimension of its image space. The framework based on the Grassmann matrices provides the means for the development of a new computational method for the solutions of the exact DAP (when such solutions exist), as well as computing approximate solutions, when exact solutions do not exist.
On computational experiments in some inverse problems of heat and mass transfer
NASA Astrophysics Data System (ADS)
Bilchenko, G. G.; Bilchenko, N. G.
2016-11-01
The results of mathematical modeling of effective heat and mass transfer on hypersonic aircraft permeable surfaces are considered. The physic-chemical processes (the dissociation and the ionization) in laminar boundary layer of compressible gas are appreciated. Some algorithms of control restoration are suggested for the interpolation and approximation statements of heat and mass transfer inverse problems. The differences between the methods applied for the problem solutions search for these statements are discussed. Both the algorithms are realized as programs. Many computational experiments were accomplished with the use of these programs. The parameters of boundary layer obtained by means of the A.A.Dorodnicyn's generalized integral relations method from solving the direct problems have been used to obtain the inverse problems solutions. Two types of blowing laws restoration for the inverse problem in interpolation statement are presented as the examples. The influence of the temperature factor on the blowing restoration is investigated. The different character of sensitivity of controllable parameters (the local heat flow and local tangent friction) respectively to step (discrete) changing of control (the blowing) and the switching point position is studied.
Newton's 1679/80 solution of the constant gravity problem
NASA Astrophysics Data System (ADS)
Erlichson, Herman
1991-08-01
In his letter of 6 January 1679/80 Hooke wrote to Newton ``in truth I agree with You that the Explicating the Curve in which a body Descending to the Center of the Earth, would circumgyrate were a Speculation of noe Use yet'' [The Correspondence of Isaac Newton, edited by H. W. Turnbull (Cambridge U.P., Cambridge, 1960), Vol. 2, p. 309]. In these words, Hooke referred to a hypothetical problem which he was discussing in a correspondence with Newton. The problem was that of determining the orbit of a body moving inside a narrow cut made centrally across the Earth. This was perhaps the very first inverse central force problem to be attacked by Newton. Newton seems to have used his instantaneous impulse technique to provide a drawing of a solution that was almost exact. This paper explores this fascinating early solution of an inverse central force problem.
Expert and novice solutions of genetic pedigree problems
NASA Astrophysics Data System (ADS)
Hackling, Mark W.; Lawrence, Jeanette A.
This study compared the problem-solving performance of university genetics professors and genetics students, and therefore fits the expert versus novice paradigm. The subjects solved three genetic pedigree problems. Data were gathered using standard think-aloud protocol procedures. Although the experts did not differ from the novices in terms of the number of correct solutions obtained, there were significant differences favoring the experts in terms of the completeness and conclusiveness of the solutions. The experts identified more critical cues in the pedigrees which were used to generate and test hypotheses, they tested more hypotheses by assigning genotypes to individuals in the pedigrees, and were more rigorous than the novices in the falsification of alternative hypotheses. The experts varied their problem-solving strategy to suit the particular conditions of problems involving rare or common traits. Novices did nor recognize the need to make such modifications to their strategies.
Heat Capacity Study of Solution Grown Crystals of Isotactic Polystyrene
Xu,H.; Cebe, P.
2005-01-01
We have performed measurements of the specific heat capacity on isotactic polystyrene (iPS) crystals grown from dilute solution. Solution grown crystal (SGC) samples had larger crystal fractions and greatly reduced rigid amorphous fractions compared to their bulk cold-crystallized counterparts. Heat capacity studies were performed from below the glass transition temperature to above the melting temperature by using quasi-isothermal temperature modulated differential scanning calorimetry (TMDSC) and standard DSC. Two or three endotherms are observed, which represent the melting of crystals. The small rigid amorphous fraction relaxes in a wide temperature range from just above the glass transition temperature to just below the first crystal melting endotherm. As in bulk iPS, 1 multiple reversing melting was found in iPS SGCs, supporting the view that double melting in iPS may be due to dual thermal stability distribution existing along one single lamella.2 The impact of reorganization and annealing on the melt endotherms was also investigated. Annealing occurs as a result of the very slow effective heating rate of the quasi-isothermal measurements compared to standard DSC. The improvement of crystal perfection through annealing causes the reversing melting endotherms to occur at a temperature higher than the endotherms seen in the standard DSC scan.
Regularized and generalized solutions of infinite-dimensional stochastic problems
Alshanskiy, Maxim A; Mel'nikova, Irina V
2011-11-30
The paper is concerned with solutions of Cauchy's problem for stochastic differential-operator equations in separable Hilbert spaces. Special emphasis is placed on the case when the operator coefficient of the equation is not a generator of a C{sub 0}-class semigroup, but rather generates some regularized semigroup. Regularized solutions of equations in the Ito form with a Wiener process as an inhomogeneity and generalized solutions of equations with white noise are constructed in various spaces of abstract distributions. Bibliography: 23 titles.
NASA Technical Reports Server (NTRS)
Murio, Diego A.
1991-01-01
An explicit and unconditionally stable finite difference method for the solution of the transient inverse heat conduction problem in a semi-infinite or finite slab mediums subject to nonlinear radiation boundary conditions is presented. After measuring two interior temperature histories, the mollification method is used to determine the surface transient heat source if the energy radiation law is known. Alternatively, if the active surface is heated by a source at a rate proportional to a given function, the nonlinear surface radiation law is then recovered as a function of the interface temperature when the problem is feasible. Two typical examples corresponding to Newton cooling law and Stefan-Boltzmann radiation law respectively are illustrated. In all cases, the method predicts the surface conditions with an accuracy suitable for many practical purposes.
Application of genetics knowledge to the solution of pedigree problems
NASA Astrophysics Data System (ADS)
Hackling, Mark W.
1994-12-01
This paper reports on a study of undergraduate genetics students' conceptual and procedural knowledge and how that knowledge influences students' success in pedigree problem solving. Findings indicate that many students lack the knowledge needed to test hypotheses relating to X-linked modes of inheritance using either patterns of inheritance or genotypes. Case study data illustrate how these knowledge deficiencies acted as an impediment to correct and conclusive solutions of pedigree problems.
Coevolving solutions to the shortest common superstring problem.
Zaritsky, Assaf; Sipper, Moshe
2004-01-01
The shortest common superstring (SCS) problem, known to be NP-Complete, seeks the shortest string that contains all strings from a given set. In this paper we compare four approaches for finding solutions to the SCS problem: a standard genetic algorithm, a novel cooperative-coevolutionary algorithm, a benchmark greedy algorithm, and a parallel coevolutionary-greedy approach. We show the coevolutionary approach produces the best results, and discuss directions for future research.
Algorithm For Solution Of Subset-Regression Problems
NASA Technical Reports Server (NTRS)
Verhaegen, Michel
1991-01-01
Reliable and flexible algorithm for solution of subset-regression problem performs QR decomposition with new column-pivoting strategy, enables selection of subset directly from originally defined regression parameters. This feature, in combination with number of extensions, makes algorithm very flexible for use in analysis of subset-regression problems in which parameters have physical meanings. Also extended to enable joint processing of columns contaminated by noise with those free of noise, without using scaling techniques.
Data Quality Problems in Army Logistics, Classification, Examples, and Solutions.
1996-01-01
state. Measuring deliveries to the supplier, as the EIA tried to do, led to significant misstatements of energy flows. Other examples include the use of...We then briefly describe potential solutions for those problems, deferring discussion of organizational problems with the EIC to Chapter Five...parties as an as- set. The retail level bears and complains about the collection costs, without recognizing the ( deferred ) benefits, while the wholesale
Numerical Solutions for Bayes Sequential Decision Approach to Bioequivalence Problem
1991-03-01
ADA3 707 2T1 -r Numerical Solutions for Bayes Sequential Decision Approach to Bioequivalence Problem Jing-Shiang Hwang Department of Statistics...Decision Approach to Bioequivalence Problem Jing-Shiang Hwang Department of Statistics Harvard University March 20, 1991 Abstract Bioequivalence is an...literatures. We address stop- ping rules for testing bioequivalence from a decision-theoretic point of view. The numerical techniques for Bayes
Preconditioning techniques for the iterative solution of scattering problems
NASA Astrophysics Data System (ADS)
Egidi, Nadaniela; Maponi, Pierluigi
2008-09-01
We consider a time-harmonic electromagnetic scattering problem for an inhomogeneous medium. Some symmetry hypotheses on the refractive index of the medium and on the electromagnetic fields allow to reduce this problem to a two-dimensional scattering problem. This boundary value problem is defined on an unbounded domain, so its numerical solution cannot be obtained by a straightforward application of usual methods, such as for example finite difference methods, and finite element methods. A possible way to overcome this difficulty is given by an equivalent integral formulation of this problem, where the scattered field can be computed from the solution of a Fredholm integral equation of second kind. The numerical approximation of this problem usually produces large dense linear systems. We consider usual iterative methods for the solution of such linear systems, and we study some preconditioning techniques to improve the efficiency of these methods. We show some numerical results obtained with two well known Krylov subspace methods, i.e., Bi-CGSTAB and GMRES.
Three-dimensional fundamental thermo-elastic solutions applied to contact problems
NASA Astrophysics Data System (ADS)
Wang, Z. P.; Wang, T.; Li, P. D.; Li, X. Y.; Chen, W. Q.; Müller, R.
2016-11-01
This paper aims to develop three-dimensional fundamental thermo-elastic solutions for an infinite/half-infinite space of a two-dimensional hexagonal quasi-crystal, which is subjected to a point heat source. Starting from the newly developed general solution in terms of quasi-harmonic potential functions, the corresponding fundamental solutions are derived by means of the trial-and-error technique. Six appropriate potential functions involved in the general solution are observed. The present fundamental solutions are applied to construct boundary integral equations governing the contact problems. Numerical calculations are performed to show the distributions of the thermo-elastic coupling field variables in a half-space subjected to a point thermal source.
Efficient analysis of transient heat transfer problems exhibiting sharp thermal gradients
NASA Astrophysics Data System (ADS)
O'Hara, P.; Duarte, C. A.; Eason, T.; Garzon, J.
2013-05-01
In this paper, heat transfer problems with sharp spatial gradients are analyzed using the Generalized Finite Element Method with global-local enrichment functions ( GFEM gl). With this approach, scale-bridging enrichment functions are generated on the fly, providing specially-tailored enrichment functions for the problem to be analyzed with no a-priori knowledge of the exact solution. In this work, a decomposition of the linear system of equations is formulated for both steady-state and transient heat transfer problems, allowing for a much more computationally efficient analysis of the problems of interest. With this algorithm, only a small portion of the global system of equations, i.e., the hierarchically added enrichments, need to be re-computed for each loading configuration or time-step. Numerical studies confirm that the condensation scheme does not impact the solution quality, while allowing for more computationally efficient simulations when large problems are considered. We also extend the GFEM gl to allow for the use of hexahedral elements in the global domain, while still using tetrahedral elements in the local domain, to allow for automatic localized mesh refinement without the use of constrained approximations. Simulations are run with the use of linear and quadratic hexahedral and tetrahedral elements in the global domain. Convergence studies indicate that the use of a different partition of unity (PoU) in the global (hexahedral elements) and local (tetrahedral elements) domains does not adversely impact the solution quality.
Multiple solutions for resonant semilinear elliptic problems in
NASA Astrophysics Data System (ADS)
López Garza, Gabriel; Rumbos, Adolfo J.
2005-05-01
We prove the existence of multiple nontrivial solutions for the semilinear elliptic problem -[Delta]u=h([lambda]u+g(u)) in , , where h[set membership, variant]L1[intersection]L[alpha] for [alpha]>N/2, N[greater-or-equal, slanted]3, g is a function that has at most linear growth at infinity, g(0)=0, and [lambda] is an eigenvalue of the corresponding linear problem -[Delta]u=[lambda]hu in , . Existence of multiple solutions, for certain values of g'(0), is obtained by imposing a generalized Landesman-Lazer type condition. We use the saddle point theorem of Ambrosetti and Rabinowitz and the mountain pass theorem, as well as a Morse-index result of Ambrosetti [A. Ambrosetti, Differential Equations with Multiple Solutions and Nonlinear Functional Analysis, Equadiff 82, Lecture Notes in Math., vol. 1017, Springer-Verlag, Berlin, 1983] and a Leray-Schauder index theorem for mountain pass type critical points due to Hofer [H. Hofer, A note on the Topological Degree at a critical Point of Mountain Pass Type, Proc. Amer. Math. Soc. 90 (1984) 309-315]. The results of this paper are based upon multiplicity results for resonant problems on bounded domains in [E. Landesman, S. Robinson, A. Rumbos, Multiple solutions of semilinear elliptic problems at resonance, Nonlinear Anal. 24 (1995) 1049-1059] and [S. Robinson, Multiple solutions for semilinear elliptic boundary value problems at resonance, Electron. J. Differential Equations 1995 (1995) 1-14], and complement a previous existence result by the authors in [G. López Garza, A. Rumbos, Resonance and strong resonance for semilinear elliptic equations in , Electron. J. Differential Equations 2003 (2003) 1-22] for resonant problems in in which g was assumed to be bounded.
Hayat, Tasawar; Ali, Shafqat; Farooq, Muhammad Asif; Alsaedi, Ahmad
2015-01-01
In this paper, we have investigated the combined effects of Newtonian heating and internal heat generation/absorption in the two-dimensional flow of Eyring-Powell fluid over a stretching surface. The governing non-linear analysis of partial differential equations is reduced into the ordinary differential equations using similarity transformations. The resulting problems are computed for both series and numerical solutions. Series solution is constructed using homotopy analysis method (HAM) whereas numerical solution is presented by two different techniques namely shooting method and bvp4c. A comparison of homotopy solution with numerical solution is also tabulated. Both solutions are found in an excellent agreement. Dimensionless velocity and temperature profiles are plotted and discussed for various emerging physical parameters. PMID:26402366
Hayat, Tasawar; Ali, Shafqat; Farooq, Muhammad Asif; Alsaedi, Ahmad
2015-01-01
In this paper, we have investigated the combined effects of Newtonian heating and internal heat generation/absorption in the two-dimensional flow of Eyring-Powell fluid over a stretching surface. The governing non-linear analysis of partial differential equations is reduced into the ordinary differential equations using similarity transformations. The resulting problems are computed for both series and numerical solutions. Series solution is constructed using homotopy analysis method (HAM) whereas numerical solution is presented by two different techniques namely shooting method and bvp4c. A comparison of homotopy solution with numerical solution is also tabulated. Both solutions are found in an excellent agreement. Dimensionless velocity and temperature profiles are plotted and discussed for various emerging physical parameters.
NASA Technical Reports Server (NTRS)
Lansing, F. L.
1979-01-01
A computer program which can distinguish between different receiver designs, and predict transient performance under variable solar flux, or ambient temperatures, etc. has a basic structure that fits a general heat transfer problem, but with specific features that are custom-made for solar receivers. The code is written in MBASIC computer language. The methodology followed in solving the heat transfer problem is explained. A program flow chart, an explanation of input and output tables, and an example of the simulation of a cavity-type solar receiver are included.
Image Indexing and Retrieval: Some Problems and Proposed Solutions.
ERIC Educational Resources Information Center
Baxter, Graeme; Anderson, Douglas
1996-01-01
Image processing technology allows libraries to include photographs, paintings, monograph title pages, and maps in their databases. This article examines problems of and solutions to image indexing and retrieval, focusing on thesaurus-based indexing systems, visual thesauri and related hybrid systems, picture description languages, and image…
Solution to the cosmological horizon problem proposed by Zee
Pollock, M.D.
1981-08-15
Applying a theory of gravity with broken symmetry, Zee has suggested a solution to the cosmological horizon problem. His idea has been criticized on two independent grounds by Linde and by Sato. In this paper, we suggest answers to both these criticisms.
[Chinglish in English medical papers: problem and its possible solution].
Wang, Zheng-ai; Song, Jian-wu
2003-08-01
This paper serves as a brief review of the problem of "Chinglish" that is frequent in English medical papers of Chinese authors, and with examples of such linguistic entity and theoretical analysis of its origin, the authors propose its possible solutions.
Image Indexing and Retrieval: Some Problems and Proposed Solutions.
ERIC Educational Resources Information Center
Baxter, Graeme; Anderson, Douglas
1996-01-01
Image processing technology allows libraries to include photographs, paintings, monograph title pages, and maps in their databases. This article examines problems of and solutions to image indexing and retrieval, focusing on thesaurus-based indexing systems, visual thesauri and related hybrid systems, picture description languages, and image…
WATER CONSERVATION: LOCAL SOLUTIONS TO A GLOBAL PROBLEM
Water conservation issues are discussed. Local solutions to a global problem include changing old habits relating to the usage and abuse of water resources. While the suggested behavioral changes may not solve the world's pending water crisis, they may ease the impact of the l...
WATER CONSERVATION: LOCAL SOLUTIONS TO A GLOBAL PROBLEM
Water conservation issues are discussed. Local solutions to a global problem include changing old habits relating to the usage and abuse of water resources. While the suggested behavioral changes may not solve the world's pending water crisis, they may ease the impact of the l...
Generic Problems or Solutions in Rural Special Education.
ERIC Educational Resources Information Center
Marrs, Lawrence W.
While most rural special education leaders agree on the universality of certain problems (funding inadequacies, personnel recruitment/retention, transportation, low-incidence handicapped populations, staff development needs, resistance to change) in rural areas, no agreement exists regarding generalizable solutions which will work in all rural…
Symmetric periodic solutions of the anisotropic Manev problem
NASA Astrophysics Data System (ADS)
Santoprete, Manuele
2002-06-01
We consider the Manev potential in an anisotropic space, i.e., such that the force acts differently in each direction. Using a generalization of the Poincaré continuation method we study the existence of periodic solutions for weak anisotropy. In particular we find that the symmetric periodic orbits of the Manev system are perturbed to periodic orbits in the anisotropic problem.
ERIC Educational Resources Information Center
Ewert, Alan
Outdoor leaders constantly face problems created by water shortage and, to act effectively, must thoroughly understand the body's use of water and the ways to delay dehydration when water shortage occurs. Dehydration begins when there is a negative water balance, or more water lost than ingested, and progresses from the stage of dryness, to the…
Mathematical modeling of heat transfer problems in the permafrost
NASA Astrophysics Data System (ADS)
Gornov, V. F.; Stepanov, S. P.; Vasilyeva, M. V.; Vasilyev, V. I.
2014-11-01
In this work we present results of numerical simulation of three-dimensional temperature fields in soils for various applied problems: the railway line in the conditions of permafrost for different geometries, the horizontal tunnel underground storage and greenhouses of various designs in the Far North. Mathematical model of the process is described by a nonstationary heat equation with phase transitions of pore water. The numerical realization of the problem is based on the finite element method using a library of scientific computing FEniCS. For numerical calculations we use high-performance computing systems.
Unified analytical solutions to two-body problems with drag
NASA Astrophysics Data System (ADS)
Breiter, S.; Jackson, A. A.
1998-08-01
The two-body problem with a generalized Stokes drag is discussed. The drag force is proportional to the product of the velocity vector and the inverse square of the distance. The generalization consists of allowing two different proportionality constants for the radial and the transverse components of the force. Under the `generalized Robertson transformation', the equation of the orbit takes the form of the Lommel equation and admits solutions in terms of Bessel and Lommel functions. The exact, analytical solutions for this type of drag reveal a paradoxical effect of increasing eccentricity for all trajectories. The Poynting-Robertson drag and Poynting-Plummer-Danby problems are discussed as particular cases of the general solution.
Degradation of aqueous DEA solutions in heat transfer tubes
Meisen, A.; Chakma, A.
1985-01-01
Experiments were performed on the degradation of aqueous diethanolamine (DEA) solutions passing through a coiled heat transfer tube (2.0032 mm ID, 3.175 mm OD, 4.8 m long) immersed in a constant temperature bath. The operating conditions were: DEA flow rate 0.011 to 0.0172 L/s, DEA concentration 20 to 40 wt%, DEA temperature 60 to 200/sup 0/C, CO/sub 2/ partial pressure 1.38 to 4.18 MPa. The degradation rate was found to increase with temperature, DEA concentration and CO/sub 2/ partial pressure; it decreased with solution flow rate. The degradation was accompanied by the formation of a fouling deposit. A simple mathematical model is presented for predicting DEA degradation.
Integrated Force Method Solution to Indeterminate Structural Mechanics Problems
NASA Technical Reports Server (NTRS)
Patnaik, Surya N.; Hopkins, Dale A.; Halford, Gary R.
2004-01-01
Strength of materials problems have been classified into determinate and indeterminate problems. Determinate analysis primarily based on the equilibrium concept is well understood. Solutions of indeterminate problems required additional compatibility conditions, and its comprehension was not exclusive. A solution to indeterminate problem is generated by manipulating the equilibrium concept, either by rewriting in the displacement variables or through the cutting and closing gap technique of the redundant force method. Compatibility improvisation has made analysis cumbersome. The authors have researched and understood the compatibility theory. Solutions can be generated with equal emphasis on the equilibrium and compatibility concepts. This technique is called the Integrated Force Method (IFM). Forces are the primary unknowns of IFM. Displacements are back-calculated from forces. IFM equations are manipulated to obtain the Dual Integrated Force Method (IFMD). Displacement is the primary variable of IFMD and force is back-calculated. The subject is introduced through response variables: force, deformation, displacement; and underlying concepts: equilibrium equation, force deformation relation, deformation displacement relation, and compatibility condition. Mechanical load, temperature variation, and support settling are equally emphasized. The basic theory is discussed. A set of examples illustrate the new concepts. IFM and IFMD based finite element methods are introduced for simple problems.
NASA Astrophysics Data System (ADS)
Zamolo, R.; Nobile, E.
2017-01-01
A Least Squares Collocation Meshless Method based on Radial Basis Function (RBF) interpolation is used to solve steady state heat conduction problems on 2D polygonal domains using MATLAB® environment. The point distribution process required by the numerical method can be fully automated, taking account of boundary conditions and geometry of the problem to get higher point distribution density where needed. Several convergence tests have been carried out comparing the numerical results to the corresponding analytical solutions to outline the properties of this numerical approach, considering various combinations of parameters. These tests showed favorable convergence properties in the simple cases considered: along with the geometry flexibility, these features confirm that this peculiar numerical approach can be an effective tool in the numerical simulation of heat conduction problems.
Addition of simultaneous heat and solute transport and variable fluid viscosity to SEAWAT
Thorne, D.; Langevin, C.D.; Sukop, M.C.
2006-01-01
SEAWAT is a finite-difference computer code designed to simulate coupled variable-density ground water flow and solute transport. This paper describes a new version of SEAWAT that adds the ability to simultaneously model energy and solute transport. This is necessary for simulating the transport of heat and salinity in coastal aquifers for example. This work extends the equation of state for fluid density to vary as a function of temperature and/or solute concentration. The program has also been modified to represent the effects of variable fluid viscosity as a function of temperature and/or concentration. The viscosity mechanism is verified against an analytical solution, and a test of temperature-dependent viscosity is provided. Finally, the classic Henry-Hilleke problem is solved with the new code. ?? 2006 Elsevier Ltd. All rights reserved.
Anti-anthropic solutions to the cosmic coincidence problem
Fedrow, Joseph M.; Griest, Kim E-mail: kgriest@ucsd.edu
2014-01-01
A cosmological constant fits all current dark energy data, but requires two extreme fine tunings, both of which are currently explained by anthropic arguments. Here we discuss anti-anthropic solutions to one of these problems: the cosmic coincidence problem- that today the dark energy density is nearly equal to the matter density. We replace the ensemble of Universes used in the anthropic solution with an ensemble of tracking scalar fields that do not require fine-tuning. This not only does away with the coincidence problem, but also allows for a Universe that has a very different future than the one currently predicted by a cosmological constant. These models also allow for transient periods of significant scalar field energy (SSFE) over the history of the Universe that can give very different observational signatures as compared with a cosmological constant, and so can be confirmed or disproved in current and upcoming experiments.
Local-instantaneous filtering in the integral transform solution of nonlinear diffusion problems
NASA Astrophysics Data System (ADS)
Macêdo, E. N.; Cotta, R. M.; Orlande, H. R. B.
A novel filtering strategy is proposed to be utilized in conjunction with the Generalized Integral Transform Technique (GITT), in the solution of nonlinear diffusion problems. The aim is to optimize convergence enhancement, yielding computationally efficient eigenfunction expansions. The proposed filters include space and time dependence, extracted from linearized versions of the original partial differential system. The scheme automatically updates the filter along the time integration march, as the required truncation orders for the user requested accuracy begin to exceed a prescribed maximum system size. A fully nonlinear heat conduction example is selected to illustrate the computational performance of the filtering strategy, against the classical single-filter solution behavior.
Semi-analytical method for solving nonlinear heat diffusion problems in spherical medium
NASA Astrophysics Data System (ADS)
Abd-El-Malek, Mina B.; Helal, Medhat M.
2006-08-01
A semi-analytical methodology, based on the finite integral transform technique, is proposed to solve the heat diffusion problem in a spherical medium subject to nonlinear boundary conditions due to radiation exchange at the interface according to the fourth power law. The method proceeds by treating the nonlinearity term in the boundary condition as a source in the differential equation and keeping other conditions unchanged. The results obtained from this semi-analytical solutions are compared with those obtained from a numerical solution developed using an explicit finite difference method, which showed very good agreement.
Haydock's recursive solution of self-adjoint problems. Discrete spectrum
NASA Astrophysics Data System (ADS)
Moroz, Alexander
2014-12-01
Haydock's recursive solution is shown to underline a number of different concepts such as (i) quasi-exactly solvable models, (ii) exactly solvable models, (iii) three-term recurrence solutions based on Schweber's quantization criterion in Hilbert spaces of entire analytic functions, and (iv) a discrete quantum mechanics of Odake and Sasaki. A recurrent theme of Haydock's recursive solution is that the spectral properties of any self-adjoint problem can be mapped onto a corresponding sequence of polynomials {pn(E) } in energy variable E. The polynomials {pn(E) } are orthonormal with respect to the density of states n0(E) and energy eigenstate | E > is the generating function of {pn(E) } . The generality of Haydock's recursive solution enables one to see the different concepts from a unified perspective and mutually benefiting from each other. Some results obtained within the particular framework of any of (i) to (iv) may have much broader significance.
A More General Solution of the Kenamond HE Problem 2
Kaul, Ann
2015-12-15
A more general solution for programmed burn calculations of the light times produced by an unobstructed line-of-sight, multi-point initiation of a composite HE region has been developed. The equations describing the interfaces between detonation fronts have also been included. In contrast to the original solutions proposed in References 1 and 2, four of the detonators are no longer restricted to specific locations on a Cartesian axis and can be located at any point inside the HE region. For the proposed solution, one detonator must be located at the origin. The more general solution for any locations on the 2D y-axis or 3D z-axis has been implemented in the ExactPack suite of exact solvers for verification problems. It could easily be changed to the most general case outlined above.
Green's function solution to spherical gradiometric boundary-value problems
NASA Astrophysics Data System (ADS)
Martinec, Z.
2003-05-01
Three independent gradiometric boundary-value problems (BVPs) with three types of gradiometric data, {orr}, {or/,or5} and {o//mo55,o/5}, prescribed on a sphere are solved to determine the gravitational potential on and outside the sphere. The existence and uniqueness conditions on the solutions are formulated showing that the zero- and the first-degree spherical harmonics are to be removed from {or/,or5} and {o//mo55,o/5}, respectively. The solutions to the gradiometric BVPs are presented in terms of Green's functions, which are expressed in both spectral and closed spatial forms. The logarithmic singularity of the Green's function at the point `=0 is investigated for the component orr. The other two Green's functions are finite at this point. Comparisons to the paper by van Gelderen and Rummel [Journal of Geodesy (2001) 75: 1-11] show that the presented solution refines the former solution.
Numerical solution-space analysis of satisfiability problems
NASA Astrophysics Data System (ADS)
Mann, Alexander; Hartmann, A. K.
2010-11-01
The solution-space structure of the three-satisfiability problem (3-SAT) is studied as a function of the control parameter α (ratio of the number of clauses to the number of variables) using numerical simulations. For this purpose one has to sample the solution space with uniform weight. It is shown here that standard stochastic local-search (SLS) algorithms like average satisfiability (ASAT) exhibit a sampling bias, as does “Metropolis-coupled Markov chain Monte Carlo” (MCMCMC) (also known as “parallel tempering”) when run for feasible times. Nevertheless, unbiased samples of solutions can be obtained using the “ballistic-networking approach,” which is introduced here. It is a generalization of “ballistic search” methods and yields also a cluster structure of the solution space. As application, solutions of 3-SAT instances are generated using ASAT plus ballistic networking. The numerical results are compatible with a previous analytical prediction of a simple solution-space structure for small values of α and a transition to a clustered phase at αc≈3.86 , where the solution space breaks up into several non-negligible clusters. Furthermore, in the thermodynamic limit there are, even for α=4.25 close to the SAT-UNSAT transition αs≈4.267 , always clusters without any frozen variables. This may explain why some SLS algorithms are able to solve very large 3-SAT instances close to the SAT-UNSAT transition.
Nucleate pool boiling heat transfer in aqueous surfactant solutions
NASA Astrophysics Data System (ADS)
Wasekar, Vivek Mahadeorao
Saturated, nucleate pool boiling in aqueous surfactant solutions is investigated experimentally. Also, the role of Marangoni convection, driven both by temperature and surfactant concentration gradients at the vapor-liquid interface of a nucleating bubble is computationally explored. Experimental measurements of dynamic and equilibrium sigma using the maximum bubble pressure method indicate dynamic sigma to be higher than the corresponding equilibrium value, both at room and elevated temperatures. Also, nonionic surfactants (Triton X-100, Triton X-305) show larger sigma depression than anionic surfactants (SDS, SLES), and a normalized representation of their dynamic adsorption isotherms is shown to be helpful in generalizing the surfactant effectiveness to reduce surface tension. The dynamic sigma has a primary role in the modification of bubble dynamics and associated heat transfer, and is dictated by the adsorption kinetics of the surfactant molecules at boiling temperatures. In general, an enhancement in heat transfer is observed, which is characterized by an early incipience and an optimum boiling performance at or around the critical micelle concentration of the surfactant. The optimum performances, typically in the fully developed boiling regime ( q''w > 100 kW/m2), show a reverse trend with respect to surfactant molecular weights M, i.e., higher molecular weight additives promote lower enhancement. Normalized boiling performance using the respective solution's dynamic sigma correlates heat transfer coefficient by M-0.5 for anionics and M 0 for nonionics. This has been shown to be brought about by the surfactant concentration and its interfacial activity in a concentration sublayer around the growing vapor bubble, which governs the bubble growth behavior through the mechanism of dynamic sigma. The ionic nature of the surfactant influences the thickness and molecular makeup of the enveloping sublayer, thereby affecting the bubble dynamics and boiling heat
On the possibility of control restoration in some inverse problems of heat and mass transfer
NASA Astrophysics Data System (ADS)
Bilchenko, G. G.; Bilchenko, N. G.
2016-11-01
The hypersonic aircraft permeable surfaces effective heat protection problems are considered. The physic-chemical processes (the dissociation and the ionization) in laminar boundary layer of compressible gas are appreciated in mathematical model. The statements of direct problems of heat and mass transfer are given: according to preset given controls it is necessary to compute the boundary layer mathematical model parameters and determinate the local and total heat flows and friction forces and the power of blowing system. The A.A.Dorodnicyn's generalized integral relations method has been used as calculation basis. The optimal control - the blowing into boundary layer (for continuous functions) was constructed as the solution of direct problem in extreme statement with the use of this approach. The statement of inverse problems are given: the control laws ensuring the preset given local heat flow and local tangent friction are restored. The differences between the interpolation and the approximation statements are discussed. The possibility of unique control restoration is established and proved (in the stagnation point). The computational experiments results are presented.
Lessons Learned During Solutions of Multidisciplinary Design Optimization Problems
NASA Technical Reports Server (NTRS)
Patnaik, Suna N.; Coroneos, Rula M.; Hopkins, Dale A.; Lavelle, Thomas M.
2000-01-01
Optimization research at NASA Glenn Research Center has addressed the design of structures, aircraft and airbreathing propulsion engines. During solution of the multidisciplinary problems several issues were encountered. This paper lists four issues and discusses the strategies adapted for their resolution: (1) The optimization process can lead to an inefficient local solution. This deficiency was encountered during design of an engine component. The limitation was overcome through an augmentation of animation into optimization. (2) Optimum solutions obtained were infeasible for aircraft and air-breathing propulsion engine problems. Alleviation of this deficiency required a cascading of multiple algorithms. (3) Profile optimization of a beam produced an irregular shape. Engineering intuition restored the regular shape for the beam. (4) The solution obtained for a cylindrical shell by a subproblem strategy converged to a design that can be difficult to manufacture. Resolution of this issue remains a challenge. The issues and resolutions are illustrated through six problems: (1) design of an engine component, (2) synthesis of a subsonic aircraft, (3) operation optimization of a supersonic engine, (4) design of a wave-rotor-topping device, (5) profile optimization of a cantilever beam, and (6) design of a cvlindrical shell. The combined effort of designers and researchers can bring the optimization method from academia to industry.
Solution Space Coupling in the Random K-Satisfiability Problem
NASA Astrophysics Data System (ADS)
Zeng, Ying; Zhou, Hai-Jun
2013-09-01
The random K-satisfiability (K-SAT) problem is very difficult when the clause density is close to the satisfiability threshold. In this paper we study this problem from the perspective of solution space coupling. We divide a given difficult random K-SAT formula into two easy sub-formulas and let the two corresponding solution spaces to interact with each other through a coupling field x. We investigate the statistical mechanical property of this coupled system by mean field theory and computer simulations. The coupled system has an ergodicity-breaking (clustering) transition at certain critical value xd of the coupling field. At this transition point, the mean overlap value between the solutions of the two solution spaces is very close to 1. The mean energy density of the coupled system at its clustering transition point is less than the mean energy density of the original K-SAT problem at the temperature-induced clustering transition point. The implications of this work for designing new heuristic K-SAT solvers are discussed.
Green's function of a heat problem with a periodic boundary condition
NASA Astrophysics Data System (ADS)
Erzhanov, Nurzhan E.
2016-08-01
In the paper, a nonlocal initial-boundary value problem for a non-homogeneous one-dimensional heat equation is considered. The domain under consideration is a rectangle. The classical initial condition with respect to t is put. A nonlocal periodic boundary condition by a spatial variable x is put. It is well-known that a solution of problem can be constructed in the form of convergent orthonormal series according to eigenfunctions of a spectral problem for an operator of multiple differentiation with periodic boundary conditions. Therefore Green's function can be also written in the form of an infinite series with respect to trigonometric functions (Fourier series). For classical first and second initial-boundary value problems there also exists a second representation of the Green's function by Jacobi function. In this paper we find the representation of the Green's function of the nonlocal initial-boundary value problem with periodic boundary conditions in the form of series according to exponents.
Is comprehension of problem solutions resistant to misleading heuristic cues?
Ackerman, Rakefet; Leiser, David; Shpigelman, Maya
2013-05-01
Previous studies in the domain of metacomprehension judgments have primarily used expository texts. When these texts include illustrations, even uninformative ones, people were found to judge that they understand their content better. The present study aimed to delineate the metacognitive processes involved in understanding problem solutions - a text type often perceived as allowing reliable judgments regarding understanding, and was not previously considered from a metacognitive perspective. Undergraduate students faced difficult problems. They then studied solution explanations with or without uninformative illustrations and provided judgments of comprehension (JCOMPs). Learning was assessed by application to near-transfer problems in an open-book test format. As expected, JCOMPs were polarized - they tended to reflect good or poor understanding. Yet, JCOMPs were higher for the illustrated solutions and even high certainty did not ensure resistance to this effect. Moreover, success in the transfer problems was lower in the presence of illustrations, demonstrating a bias stronger than that found with expository texts. Previous studies have suggested that weak learners are especially prone to being misled by superficial cues. In the present study, matching the difficulty of the task to the ability of the target population revealed that even highly able participants were not immune to misleading cues. The study extends previous findings regarding potential detrimental effects of illustrations and highlights aspects of the metacomprehension process that have not been considered before.
The exact fundamental solution for the Benes tracking problem
NASA Astrophysics Data System (ADS)
Balaji, Bhashyam
2009-05-01
The universal continuous-discrete tracking problem requires the solution of a Fokker-Planck-Kolmogorov forward equation (FPKfe) for an arbitrary initial condition. Using results from quantum mechanics, the exact fundamental solution for the FPKfe is derived for the state model of arbitrary dimension with Benes drift that requires only the computation of elementary transcendental functions and standard linear algebra techniques- no ordinary or partial differential equations need to be solved. The measurement process may be an arbitrary, discrete-time nonlinear stochastic process, and the time step size can be arbitrary. Numerical examples are included, demonstrating its utility in practical implementation.
A Solution Method for Large Deformation Contact Problems.
1984-10-01
number) Contact Problem Algorithm Implicit Solution Technique 20. ANSTNACT’ (rntftae r eves aIi N yaeemy mrd identify by block numnber) P. solution...WITHOUT oL0 H! 0-CONTACT ALGORITHM Z w 00 0 ev 0.8- w kL 0.0 0 U< O0.26 U)_ * z Z OBTINE 0H53 56 59 ANGE,4 Ficure~~~~~ ~*A G RI H 17 Peitdtatoso iesi itrae...41, Division of Applied Sciences, Harvard Univ., March 1983. [20] Rabinowicz , E., Friction and Wear of Materials, J. Wiley and Sons, 1965. [21
Combinatorial optimization problem solution based on improved genetic algorithm
NASA Astrophysics Data System (ADS)
Zhang, Peng
2017-08-01
Traveling salesman problem (TSP) is a classic combinatorial optimization problem. It is a simplified form of many complex problems. In the process of study and research, it is understood that the parameters that affect the performance of genetic algorithm mainly include the quality of initial population, the population size, and crossover probability and mutation probability values. As a result, an improved genetic algorithm for solving TSP problems is put forward. The population is graded according to individual similarity, and different operations are performed to different levels of individuals. In addition, elitist retention strategy is adopted at each level, and the crossover operator and mutation operator are improved. Several experiments are designed to verify the feasibility of the algorithm. Through the experimental results analysis, it is proved that the improved algorithm can improve the accuracy and efficiency of the solution.
Geometric projection filter: an efficient solution to the SLAM problem
NASA Astrophysics Data System (ADS)
Newman, Paul M.; Durrant-Whyte, Hugh F.
2001-10-01
This paper is concerned with the simultaneous localization and map building (SLAM) problem. The SLAM problem asks if it is possible for an autonomous vehicle to start in an unknown location in an unknown environment and then to incrementally build a map of this environment while simultaneously using this map to compute absolute vehicle location. Conventional approaches to this problem are plagued with a prohibitively large increase in computation with the size of the environment. This paper offers a new solution to the SLAM problem that is both consistent and computationally feasible. The proposed algorithm builds a map expressing the relationships between landmarks which is then transformed into landmark locations. Experimental results are presented employing the new algorithm on a subsea vehicle using a scanning sonar sensor.
A coupled model of soil water-heat-solute movement under the mulched drip irrigation condition
NASA Astrophysics Data System (ADS)
Hu, H.; Tian, F.; Gao, L.; Hu, H.
2010-12-01
: The mulched drip irrigation (MDI), first developed in northwestern part of China (Xinjiang Province) in the cotton field in 1996, can obtain higher yield while at the lower cost of water consumption and thus becomes popular rapidly. However, it has the potential risk of salinizing the arable soil. Also, plastic film can alter the energy balance at the ground surface and invoke the regime shifting of soil heat transfer. It is, therefore, necessary to simulate the inter-related movement of water, heat, and dissolvable solute in the soil under the MDI condition for the purpose of sustainable agricultural production as well as of climate change issue. With the different boundary condition and irrigation rate, the transportation and distribution features of water-heat-salt under the MDI condition are significantly different from those under the other irrigation methods. The existing tools such as HYDRUS and VS2DH(T) could not set up the special boundary condition relevant to MDI, e.g., the moving ponded area. A new two-dimensional numerical model of Richard’s equation and Convection-Dispersion equations was developed which coupled soil water, solute, and heat together. For the homogenous and isotropic porous media, the soil water-heat-solute movement under the MDI condition is considered as 2D problem. The Richards and solute convection-diffusive equations are transformed into ordinary differential equations (ODEs) through spatial semi-discretization, and so do the corresponding boundary conditions. The resultant ODEs are solved using a state-of-the-art solver, CVODE developed at the Lawrence Livermore National Laboratory. The model is validated against the numerical examples as well as the field data. The results show the high numerical efficiency, the high simulation accuracy, and the flexibility of the model to mimic changing boundary conditions. Key words: numerical model, Richard’s equation, Convection-Diffusive equation, CVODE
Solution of exterior acoustic problems by the boundary element method
NASA Astrophysics Data System (ADS)
Kirkup, Stephen Martin
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 and Werner/Leis/Panich/Kussmaul (indirect) and Burton and 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.
Solution of Exterior Acoustic Problems by the Boundary Element Method.
NASA Astrophysics Data System (ADS)
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.
Solution of magnetometry problems related to monitoring remote pipeline systems
NASA Astrophysics Data System (ADS)
Sergeev, Andrey V.; Denisov, Alexey Y.; Narkhov, Eugene D.; Sapunov, Vladimir A.
2016-09-01
The purpose of this paper is to solve two fundamental tasks, i.e., to design the pipeline model with sufficient adequacy and reproducibility, and to solve the inverse problem for the transition from the experimental data on the magnetic field in the measurement area directly to the pipeline characteristics, which are necessary for mapping pipes location and finding coordinates of welds. The paper presents a mathematical ideal pipeline model in the geomagnetic field without considering the pipe material. The solution of the direct and inverse problems are described, and the directions of the model development and methods of data interpretation are presented.
Formalization of a synthesis problem and methods for its solution
NASA Astrophysics Data System (ADS)
Dokukin, A. A.
2014-06-01
A formal formulation is proposed for the synthesis problem of finding objects with certain properties described only by a collection of precedents. A key feature of this formalization is that it is closely related to the pattern recognition theory. A general approach to solving the synthesis problem is described, and particular solution methods are presented in two important cases. For this purpose, a new recognition method is proposed that exhibits a high speed as applied to the data of the structure under study. The performance of the methods is demonstrated on actual data.
Multiresolution strategies for the numerical solution of optimal control problems
NASA Astrophysics Data System (ADS)
Jain, Sachin
There exist many numerical techniques for solving optimal control problems but less work has been done in the field of making these algorithms run faster and more robustly. The main motivation of this work is to solve optimal control problems accurately in a fast and efficient way. Optimal control problems are often characterized by discontinuities or switchings in the control variables. One way of accurately capturing the irregularities in the solution is to use a high resolution (dense) uniform grid. This requires a large amount of computational resources both in terms of CPU time and memory. Hence, in order to accurately capture any irregularities in the solution using a few computational resources, one can refine the mesh locally in the region close to an irregularity instead of refining the mesh uniformly over the whole domain. Therefore, a novel multiresolution scheme for data compression has been designed which is shown to outperform similar data compression schemes. Specifically, we have shown that the proposed approach results in fewer grid points in the grid compared to a common multiresolution data compression scheme. The validity of the proposed mesh refinement algorithm has been verified by solving several challenging initial-boundary value problems for evolution equations in 1D. The examples have demonstrated the stability and robustness of the proposed algorithm. The algorithm adapted dynamically to any existing or emerging irregularities in the solution by automatically allocating more grid points to the region where the solution exhibited sharp features and fewer points to the region where the solution was smooth. Thereby, the computational time and memory usage has been reduced significantly, while maintaining an accuracy equivalent to the one obtained using a fine uniform mesh. Next, a direct multiresolution-based approach for solving trajectory optimization problems is developed. The original optimal control problem is transcribed into a
The Crystal-Solution Problem of Sperm Whale Myoglobin
Urnes, Peter
1965-01-01
The central question to be discussed in this paper is whether the structure established for sperm whale myoglobin in the crystalline state is the same as that of the protein in solution. As judged by its ultraviolet optical rotatory dispersion, the helical content of metmyoglobin in solution does not differ from that in the crystal, 77 per cent. Although an uncertainty of about ±5 per cent must attach to this result, it excludes many alternative arrangements of the polypeptide chain. The folding of the chain may be further restricted to the basic form seen in the crystal if the dimensions of the molecule in solution and the interactions of specific chemical groups are taken into account. Since the rotatory dispersion of metmyoglobin is constant with respect to ionic strength, and since the dispersions of reduced and oxymyoglobin reveal no change in helical content upon their formation from metmyoglobin, one may infer that the structure of the protein is largely maintained both as it dissolves and during its reversible combination with oxygen. The crystallographic model of myoglobin thus offers a structural basis for attempting to explain its physiological function in solution. The relevance of this conclusion to the crystal-solution problems presented by other species of protein is then best seen in the light of common factors that govern the equilibrium of all proteins between crystal and solution. PMID:5859928
Baggie: A unique solution to an orbiter icing problem
NASA Technical Reports Server (NTRS)
Walkover, L. J.
1982-01-01
The orbiter icing problem, located in two lower surface mold line cavities, was solved. These two cavities are open during Shuttle ground operations and ascent, and are then closed after orbit insertion. If not protected, these cavities may be coated with ice, which may be detrimental to the adjacent thermal protection system (TPS) tiles if the ice breaks up during ascent, and may hinder the closing of the cavity doors if the ice does not break up. The problem of ice in these cavities was solved by the use of a passive mechanism called baggie, which is purge curtain used to enclose the cavity and is used in conjunction with gaseous nitrogen as the local purge gas. The baggie, the final solution, is unique in its simplicity, but its design and development were not. The final baggie design and its development testing are discussed. Also discussed are the baggie concepts and other solutions not used.
Energy estimate and fundamental solution for degenerate hyperbolic Cauchy problems
NASA Astrophysics Data System (ADS)
Ascanelli, Alessia; Cicognani, Massimo
The aim of this paper is to give an uniform approach to different kinds of degenerate hyperbolic Cauchy problems. We prove that a weakly hyperbolic equation, satisfying an intermediate condition between effective hyperbolicity and the C∞ Levi condition, and a strictly hyperbolic equation with non-regular coefficients with respect to the time variable can be reduced to first-order systems of the same type. For such a kind of systems, we prove an energy estimate in Sobolev spaces (with a loss of derivatives) which gives the well-posedness of the Cauchy problem in C∞. In the strictly hyperbolic case, we also construct the fundamental solution and we describe the propagation of the space singularities of the solution which is influenced by the non-regularity of the coefficients with respect to the time variable.
There are solutions to LWD depth measurement problems
Tait, C.A.; Hamlin, K.H.
1996-03-18
The use of well-calibrated depth control sensors, good bookkeeping practices with the pipe tally, and better operating practices can help eliminate depth measurement errors on logs produced from logging-while-drilling tools. Other factors that help eliminate depth errors include advances in tool technology and mathematical corrections for tensional stretch, ballooning effect, and thermal expansion of the drill pipe. Accurate depth measurements are required to achieve wire line-quality logs with logging-while-drilling (LWD) tools. Without good depth control, pay zone thickness measurements can be in error, correlation between LWD logs and wire line logs can be poor, and subsequent LWD runs may produce data at differing depths. Critical depth control problems include nonlinearities caused by the draw works, heave effects, and drill pipe stretch and compression. An interdisciplinary team investigated the causes and various solutions to these problems and developed solution comprised of improvements in hardware, rig site operating procedures, and calibration techniques.
Computing group cardinality constraint solutions for logistic regression problems.
Zhang, Yong; Kwon, Dongjin; Pohl, Kilian M
2017-01-01
We derive an algorithm to directly solve logistic regression based on cardinality constraint, group sparsity and use it to classify intra-subject MRI sequences (e.g. cine MRIs) of healthy from diseased subjects. Group cardinality constraint models are often applied to medical images in order to avoid overfitting of the classifier to the training data. Solutions within these models are generally determined by relaxing the cardinality constraint to a weighted feature selection scheme. However, these solutions relate to the original sparse problem only under specific assumptions, which generally do not hold for medical image applications. In addition, inferring clinical meaning from features weighted by a classifier is an ongoing topic of discussion. Avoiding weighing features, we propose to directly solve the group cardinality constraint logistic regression problem by generalizing the Penalty Decomposition method. To do so, we assume that an intra-subject series of images represents repeated samples of the same disease patterns. We model this assumption by combining series of measurements created by a feature across time into a single group. Our algorithm then derives a solution within that model by decoupling the minimization of the logistic regression function from enforcing the group sparsity constraint. The minimum to the smooth and convex logistic regression problem is determined via gradient descent while we derive a closed form solution for finding a sparse approximation of that minimum. We apply our method to cine MRI of 38 healthy controls and 44 adult patients that received reconstructive surgery of Tetralogy of Fallot (TOF) during infancy. Our method correctly identifies regions impacted by TOF and generally obtains statistically significant higher classification accuracy than alternative solutions to this model, i.e., ones relaxing group cardinality constraints.
Solution of prey-predator problem by multistage decomposition method
NASA Astrophysics Data System (ADS)
Chowdhury, M. S. H.; Hashim, I.; Mawa, S.
2008-01-01
The prey-predator problem is simulated by an adaptation of the classical Adomian decomposition method (ADM). The classical ADM is converted into a hybrid numeric-analytic method called the multistage ADM (MADM). The decomposition solutions presented by previous authors are corrected. The numerical results obtained from the MADM and the classical fourth-order Rungge-Kutta (RK4) method are in complete agreement.
Spectral solution of acoustic wave-propagation problems
NASA Technical Reports Server (NTRS)
Kopriva, David A.
1990-01-01
The Chebyshev spectral collocation solution of acoustic wave propagation problems is considered. It is shown that the phase errors decay exponentially fast and that the number of points per wavelength is not sufficient to estimate the phase accuracy. Applications include linear propagation of a sinusoidal acoustic wavetrain in two space dimensions, and the interaction of a sound wave with the bow shock formed by placing a cylinder in a uniform Mach 4 supersonic free stream.
Exact Solutions of Relativistic Bound State Problem for Spinless Bosons
NASA Astrophysics Data System (ADS)
Aslanzadeh, M.; Rajabi, A. A.
2017-01-01
We investigated in detail the relativistic bound states of spin-zero bosons under the influence of Coulomb-plus-linear potentials with an arbitrary combination of scalar and vector couplings. Through an exact analytical solution of three-dimensional Klein-Gordon equation, closed form expressions were derived for energy eigenvalues and wave functions and some correlations between potential parameters were found. We also presented the relativistic description of bound states and nonrelativistic limit of the problem in some special cases.
The Solution of Linear Complementarity Problems on an Array Processor.
1981-01-01
WISCONSIN-MADISON MATHEMATICS RESEARCH CENTER THE SOLUTION OF LINEAR COMPLEMENTARITY PROBLEMS ON AN ARRAY PROCESSOR C. W. Cryer* ’ 1 , P. M. Flanders...8217, D. J. Hunt+ , S. F. Reddaway+ , and J. Stansbury**’ 1 Technical Summary Report #2170 January 1981 ABSTRACT The Distributed Array Processor (DAP...manufactured by International Computers Limited is an array of 1 -bit 200-nanosecond processors. The Pilot DAP on which the present work was done is a 32
Doughty, C.; Pruess, K.
1991-06-01
Over the past few years the authors have developed a semianalytical solution for transient two-phase water, air, and heat flow in a porous medium surrounding a constant-strength linear heat source, using a similarity variable {eta} = r/{radical}t. Although the similarity transformation approach requires a simplified geometry, all the complex physical mechanisms involved in coupled two-phase fluid and heat flow can be taken into account in a rigorous way, so that the solution may be applied to a variety of problems of current interest. The work was motivated by adverse to predict the thermohydrological response to the proposed geologic repository for heat-generating high-level nuclear wastes at Yucca Mountain, Nevada, in a partially saturated, highly fractured volcanic formation. The paper describes thermal and hydrologic conditions near the heat source; new features of the model; vapor pressure lowering; and the effective-continuum representation of a fractured/porous medium.
Reflectance of acoustic horns and solution of the inverse problem
Rasetshwane, Daniel M.; Neely, Stephen T.; Allen, Jont B.; Shera, Christopher A.
2012-01-01
A method is described for solving the inverse problem of determining the profile of an acoustic horn when time-domain reflectance (TDR) is known only at the entrance. The method involves recasting Webster’s horn equation in terms of forward and backward propagating wave variables. An essential feature of this method is a requirement that the backward propagating wave be continuous at the wave-front at all locations beyond the entrance. Derivation of the inverse solution raises questions about the meaning of causality in the context of wave propagation in non-uniform tubes. Exact reflectance expressions are presented for infinite exponential, conical and parabolic horns based on exact solutions of the horn equation. Diameter functions obtained with the inverse solution are a good match to all three horn profiles. PMID:22423684
An Improved Differential Evolution Solution for Software Project Scheduling Problem
Biju, A. C.; Victoire, T. Aruldoss Albert; Mohanasundaram, Kumaresan
2015-01-01
This paper proposes a differential evolution (DE) method for the software project scheduling problem (SPSP). The interest on finding a more efficient solution technique for SPSP is always a topic of interest due to the fact of ever growing challenges faced by the software industry. The curse of dimensionality is introduced in the scheduling problem by ever increasing software assignments and the number of staff who handles it. Thus the SPSP is a class of NP-hard problem, which requires a rigorous solution procedure which guarantees a reasonably better solution. Differential evolution is a direct search stochastic optimization technique that is fairly fast and reasonably robust. It is also capable of handling nondifferentiable, nonlinear, and multimodal objective functions like SPSP. This paper proposes a refined DE where a new mutation mechanism is introduced. The superiority of the proposed method is experimented and demonstrated by solving the SPSP on 50 random instances and the results are compared with some of the techniques in the literature. PMID:26495419
Solution of the plane stochastic creep boundary value problem
NASA Astrophysics Data System (ADS)
Kovalenko, L. V.; Popov, N. N.; Radchenko, V. P.
2009-01-01
The solution of the non-linear stochastic boundary-value problem of the creep of a thin plate in a plane stress state when the elastic strains are small and can be neglected is presented. The plate material is stochastically inhomogeneous so that the stress and strain tensors are random functions of the coordinates. The constitutive creep relation, taken as in non-linear viscous flow theory, is formulated in a stochastic form. Using the perturbation method, the non-linear stochastic problem is reduced to a system of three linear partial differential equations in the fluctuations of the stress tensor and, then, changing by implementing the stress function, to a differential equation, the solution of which is represented in the form of the sum of two series. The first series is the solution far from the boundary of the plate, ignoring edge effects, and the second is the solution in the boundary layer, and its terms rapidly decay as the distance from the boundary of the plate increases. The stretching of a stochastically inhomogeneous half-plane in the direction of two mutually orthogonal axes is considered as an example. The stress concentration in the boundary of the half-plane is investigated. It is shown that the spread of the stresses in the surface layer, the width of which depends on the degree of non-linearity of the material, can be much greater than in the deep layers.
Periodic solutions about the collinear Lagrangian solution in the general problem of three bodies
NASA Technical Reports Server (NTRS)
Broucke, R.; Davoust, E.; Anderson, J. D.; Lass, H.; Blitzer, L.
1981-01-01
The article describes the solutions near Lagrange's circular collinear configuration in the planar problem of three bodies with three finite masses. The article begins with a detailed review of the properties of Lagrange's collinear solution. Lagrange's quintic equation is derived and several expressions are given for the angular velocity of the rotating frame. The equations of motion are then linearized near the circular collinear solution, and the characteristic equation is also derived in detail. The different types of roots and their corresponding solutions are discussed. The special case of two equal outer masses receives special attention, as well as the special case of two small outer masses. Finally, the fundamental family of periodic solutions is extended by numerical integration all the way up to and past a binary collision orbit. The stability and the bifurcations of this family are briefly enumerated.
Topological inversion for solution of geodesy-constrained geophysical problems
NASA Astrophysics Data System (ADS)
Saltogianni, Vasso; Stiros, Stathis
2015-04-01
Geodetic data, mostly GPS observations, permit to measure displacements of selected points around activated faults and volcanoes, and on the basis of geophysical models, to model the underlying physical processes. This requires inversion of redundant systems of highly non-linear equations with >3 unknowns; a situation analogous to the adjustment of geodetic networks. However, in geophysical problems inversion cannot be based on conventional least-squares techniques, and is based on numerical inversion techniques (a priori fixing of some variables, optimization in steps with values of two variables each time to be regarded fixed, random search in the vicinity of approximate solutions). Still these techniques lead to solutions trapped in local minima, to correlated estimates and to solutions with poor error control (usually sampling-based approaches). To overcome these problems, a numerical-topological, grid-search based technique in the RN space is proposed (N the number of unknown variables). This technique is in fact a generalization and refinement of techniques used in lighthouse positioning and in some cases of low-accuracy 2-D positioning using Wi-Fi etc. The basic concept is to assume discrete possible ranges of each variable, and from these ranges to define a grid G in the RN space, with some of the gridpoints to approximate the true solutions of the system. Each point of hyper-grid G is then tested whether it satisfies the observations, given their uncertainty level, and successful grid points define a sub-space of G containing the true solutions. The optimal (minimal) space containing one or more solutions is obtained using a trial-and-error approach, and a single optimization factor. From this essentially deterministic identification of the set of gridpoints satisfying the system of equations, at a following step, a stochastic optimal solution is computed corresponding to the center of gravity of this set of gridpoints. This solution corresponds to a
Finite analytic numerical solution of heat transfer and flow past a square channel cavity
NASA Technical Reports Server (NTRS)
Chen, C.-J.; Obasih, K.
1982-01-01
A numerical solution of flow and heat transfer characteristics is obtained by the finite analytic method for a two dimensional laminar channel flow over a two-dimensional square cavity. The finite analytic method utilizes the local analytic solution in a small element of the problem region to form the algebraic equation relating an interior nodal value with its surrounding nodal values. Stable and rapidly converged solutions were obtained for Reynolds numbers ranging to 1000 and Prandtl number to 10. Streamfunction, vorticity and temperature profiles are solved. Local and mean Nusselt number are given. It is found that the separation streamlines between the cavity and channel flow are concave into the cavity at low Reynolds number and convex at high Reynolds number (Re greater than 100) and for square cavity the mean Nusselt number may be approximately correlated with Peclet number as Nu(m) = 0.365 Pe exp 0.2.
A possible solution of the cosmological constant problem
NASA Astrophysics Data System (ADS)
Klinkhamer, Frans R.
A brief introduction to the famous "cosmological constant problem" is given. Then, a particular approach is discussed, which has been developed by Volovik and the present speaker over the last years. The talk will aimed at a non-expert audience, skipping all technicalities. The basic idea is that the standard model of elementary particle physics and the theory of general relativity can be extended by the introduction of a vacuum variable which is responsible for the near vanishing of the present cosmological constant (vacuum energy density). The explicit realization of this vacuum variable can be via a three-form gauge field, an aether-type velocity field, or any other field appropriate for the description of the equilibrium state corresponding to the Lorentz-invariant quantum vacuum. The extended theory has, without fine-tuning, a Minkowski-type solution of the field equa-tions with spacetime-independent fields and, thereby, provides a possible solution of the main cosmological constant problem. Other problems are briefly discussed, in particular, the so-called cosmic coincidence problem.
Evolution of the General Solution of the Restricted Problem Covering Symmetric and Escape Solutions
NASA Astrophysics Data System (ADS)
Goudas, C. L.; Papadakis, K. E.
2006-12-01
The work presented in paper I (Papadakis, K.E., Goudas, C.L.: Astrophys. Space Sci. (2006)) is expanded here to cover the evolution of the approximate general solution of the restricted problem covering symmetric and escape solutions for values of μ in the interval [0, 0.5]. The work is purely numerical, although the available rich theoretical background permits the assertions that most of the theoretical issues related to the numerical treatment of the problem are known. The prime objective of this work is to apply the ‘Last Geometric Theorem of Poincaré’ (Birkhoff, G.D.: Trans. Amer. Math. Soc. 14, 14 (1913); Poincaré, H.: Rend. Cir. Mat. Palermo 33, 375 (1912)) and compute dense sets of axisymmetric periodic family curves covering the initial conditions space of bounded motions for a discrete set of values of the basic parameter μ spread along the entire interval of permissible values. The results obtained for each value of μ, tested for completeness, constitute an approximation of the general solution of the problem related to symmetric motions. The approximate general solution of the same problem related to asymmetric solutions, also computable by application of the same theorem (Poincaré-Birkhoff) is left for a future paper. A secondary objective is identification-computation of the compact space of escape motions of the problem also for selected values of the mass parameter μ. We first present the approximate general solution for the integrable case μ = 0 and then the approximate solution for the nonintegrable case μ = 10-3. We then proceed to presenting the approximate general solutions for the cases μ = 0.1, 0.2, 0.3, 0.4, and 0.5, in all cases building them in four phases, namely, presenting for each value of μ, first all family curves of symmetric periodic solutions that re-enter after 1 oscillation, then adding to it successively, the family curves that re-enter after 2 to 10 oscillations, after 11 to 30 oscillations, after 31 to 50
Satellite power systems for Western Europe - Problems and solution proposals
NASA Astrophysics Data System (ADS)
Ruth, J.; Westphal, W.
1980-08-01
This paper deals with the potential utilization of solar satellite power systems (SPS) as baseload powerplants for Western European countries. There are significant differences compared with the U.S.A. for geographical, political, organizational, orbital, and industrial reasons. These differences have been analyzed and critically examined, but no unsurmountable problems have been found. There exist, however, a lot of challenging problems to be solved prior to a full scale SPS development. In this paper some of the most important problems are presented and some potential solutions are discussed. Finally, a research program is proposed, which could help to answer the following question: Is it possible to develop, construct and operate an SPS system which is (1) economically viable, (2) technically feasible, (3) environmentally compatible, and (4) politically acceptable.
The problem, solution, and the results: holography combating counterfeit
NASA Astrophysics Data System (ADS)
Wood, Peter H. L.
1990-04-01
Counterfeiting is now a major industry estimated to be worth in excess of $100 billion - sales by the legal owners. This situation has been allowed to occur simply as a result of industries reactive/passive approach to the problem. The situation has been further complicated by the: * rapid development, availabilityofsophisticated machinery in the manufacturing technology where products can be replicated easily at a minimal cost * advances in printing technology allowing for undetectable duplication of complex printing systems with photocopy ease and considerable economies. The combination of these two factors has allowed the rapid growth of this illegal activity, creating a substantial income with little or not risk. Legal recourse is generally weak and at best reactive to the existence of the problem after the damage has been done. It would appear that industry has still not found an adequate solution to the problem, with growth in counterfeiting estimated to have increased by 150% in 5 years.
A solution to the decompactification problem in chiral heterotic strings
NASA Astrophysics Data System (ADS)
Florakis, Ioannis; Rizos, John
2017-08-01
We present a solution to the decompactification problem of gauge thresholds in chiral heterotic string theories with two large extra dimensions, where supersymmetry is spontaneously broken by the Scherk-Schwarz mechanism. Whenever the Kaluza-Klein scale that controls supersymmetry breaking is much lower than the string scale, the infinite towers of heavy states contribute non-trivially to the renormalisation of gauge couplings, which typically grow linearly with the large volume of the internal space and invalidate perturbation theory. We trace the origin of the decompactification problem to properties of the six dimensional theory obtained in the infinite volume limit and show that thresholds may instead exhibit logarithmic volume dependence and we provide the conditions for this to occur. We illustrate this mechanism with explicit string constructions where the decompactification problem does not occur.
Improved regularized solution of the inverse problem in turbidimetric measurements.
Mroczka, Janusz; Szczuczyński, Damian
2010-08-20
We present results of simulation research on the constrained regularized least-squares (RLS) solution of the ill-conditioned inverse problem in turbidimetric measurements. The problem is formulated in terms of the discretized Fredholm integral equation of the first kind. The inverse problem in turbidimetric measurements consists in determining particle size distribution (PSD) function of particulate system on the basis of turbidimetric measurements. The desired PSD should satisfy two constraints: nonnegativity of PSD values and normalization of PSD to unity when integrated over the whole range of particle size. Incorporating the constraints into the RLS method leads to the constrained regularized least-squares (CRLS) method, which is realized by means of an active set algorithm of quadratic programming. Results of simulation research prove that the CRLS method performs considerably better with reconstruction of PSD than the RLS method in terms of better fidelity and smaller uncertainty.
NASA Astrophysics Data System (ADS)
Alipova, B. N.; Alexeyeva, L. A.; Dadayeva, A. N.
2017-01-01
Generalized solutions of coupled thermoelastodynamics equations are considered. By use of generalized functions theory, the conditions on jumps of stresses, velocities, temperature gradients and energy density on their fronts are received. The statements of four non-stationary boundary value problems of coupled thermoelasticity are given, for which uniqueness of decisions are proved by influence of shock thermoelastic waves.
NASA Technical Reports Server (NTRS)
Beckett, P. M.
1981-01-01
The proposed method for the treatment of two dimensional solidification problems is based on quasilinearization of the transformed heat conduction equation and latent heat condition at the interface and an iterative sequence in which these are solved simultaneously. Modern algorithms for solving such sparse systems mean that most of the storage advantage of other methods are reduced and the speed of solution can be improved.
NASA Technical Reports Server (NTRS)
Beckett, P. M.
1981-01-01
The proposed method for the treatment of two dimensional solidification problems is based on quasilinearization of the transformed heat conduction equation and latent heat condition at the interface and an iterative sequence in which these are solved simultaneously. Modern algorithms for solving such sparse systems mean that most of the storage advantage of other methods are reduced and the speed of solution can be improved.
NASA Astrophysics Data System (ADS)
Marinca, Vasile; Ene, Remus-Daniel
2017-01-01
In this paper, the Optimal Homotopy Perturbation Method (OHPM) is employed to determine an analytic approximate solution for the nonlinear MHD Jeffery-Hamel flow and heat transfer problem. The Navier-Stokes equations, taking into account Maxwell's electromagnetism and heat transfer, lead to two nonlinear ordinary differential equations. The results obtained by means of OHPM show very good agreement with numerical results and with Homotopy Perturbation Method (HPM) results.
Regular boundary value problems for the heat equation with scalar parameters
NASA Astrophysics Data System (ADS)
Kalmenov, Tynysbek Sh.; Besbaev, Gani; Medetbekova, Ryskul
2017-09-01
This paper belongs to the general theory of well-posed initial-boundary value problems for parabolic equations. The classical construction of a boundary value problem is as follows: an equation and a boundary condition are given. It is necessary to investigate the solvability of this problem and properties of the solution if it exists (in the sense of belonging to some space). Beginning with the papers of J. von Neumann and M.I. Vishik (1951), there exists another more general approach: an equation and a space are given, right-hand parts of the equation and boundary conditions, and a solution must belong to this space. It is necessary to describe all the boundary conditions, for which the problem is correctly solvable in this space. Further development of this theory was given by M. Otelbaev, who constructed a complete theory for ordinary differential operators and for symmetric semibounded operators in a Banach space. In this paper we find regular solution of the regular boundary problem for the heat equation with scalar parameter.
Isothermal heat measurements of TBP-nitric acid solutions
Smith, J.R.; Cavin, W.S.
1994-12-16
Net heats of reaction were measured in an isothermal calorimeter for both single phase (organic) and two phase (organic and aqueous) TBP/HNO{sub 3} reacting solutions at temperatures above 100 C. The oxidation rate constant was determined to be 5.4E-4 min{sup {minus}1} at 110 C for an open ``vented`` system as compared to 1.33 E-3 min{sup {minus}1} in the closed system. The heat released per unit material oxidized was also reduced. The oxidation in both phases was found to be first order in nitric acid and pseudo-zero order in butylnitrate and water. The hydrolysis (esterification) rate constant determined by Nichols` (1.33E-3 min{sup {minus}1}) fit the experimental data from this work well. Forced evaporation of the volatile components by the product gases from oxidation resulted in a cooling mechanism which more than balanced the heat from the oxidation reaction in the two-phased systems. Rate expressions were derived and rate constants determined for both the single and two phase systems. An approximating mathematical model was developed to fit the experimental data and to extrapolate beyond the experimental conditions. This model shows that one foot of ``reacting`` 14.3M HNO{sub 3} aqueous phase solution at 121 C will transport sufficient water to the organic phase to replace evaporative losses, maintaining endothermicity, for organic layers up to 12.2 + 6.0 feet deep. If the pressure in a reacting system is allowed to increase due to insufficient venting the temperature of the organic phase would increase in temperature to reach a new equilibrium. The rate of oxidation would increase not only due to the increase in temperature but also from the increased concentration of dissolved HNO{sub 3} reduction products. Another important factor is that the cooling system described in this work becomes less effective as the total pressure increases. These factors probably contributed to the explosion at Tomsk.
Hydrothermal fluxes of solutes, carbon, and heat to Himalayan rivers
NASA Astrophysics Data System (ADS)
Evans, Matthew Jared
Hot springs flow along the base of the Himalayan front in the Narayani river basin of central Nepal. The springs flow near the Main Central Thrust (MCT), in a zone characterized by active uplift and high incision and erosion rates. Water-rock interaction at depth results in hydrothermal fluids with high solute loads. Himalayan rivers flowing through the zones of geothermal activity are enriched in cations, chloride, radiogenic strontium, and germanium. We use a comprehensive sample set of hot spring and river waters to asses the impact of the springs on the chemistry of the Narayani, and to investigate subsurface processes which control the hydrothermal fluid chemistry. Quantification of the hydrothermal fluxes of solutes, carbon dioxide, and heat to the surface depends on hot spring discharge. A chemical mass balance estimate using the high germanium concentrations in the springs yields hot spring discharge near 0.5% of the river discharge. The chemistry of the springs indicates that 12 to 100% of the total alkalinity in the springs is derived from silicates, and hot springs collectively deliver 20% of the silicate alkalinity in the Narayani. High germanium-silicon ratios in the springs can be modeled as a combination of thermodynamic equilibrium effects and Rayleigh fractionation during quartz precipitation. Active degassing and high dissolved carbon dioxide concentrations indicate that the springs are a source of CO2. High delta 13C values in the springs can be modeled with a metamorphic source and extensive sub-surface degassing. CO2 released during metamorphic decarbonation reactions is entrained in the meteoric water of the hydrothermal system. The CO2 flux from the springs is comparable to the total uptake of CO2 by silicate weathering in the Narayani drainage, which suggests that the Himalayan orogen may be a net source of CO2 to the atmosphere. Hydrothermal heat loss is near 745 +/- 313 megawatts. The high heat flux is the result of tectonic
The Joule heating problem in silver nanowire transparent electrodes.
Khaligh, H H; Xu, L; Khosropour, A; Madeira, A; Romano, M; Pradére, C; Tréguer-Delapierre, M; Servant, L; Pope, M A; Goldthorpe, I A
2017-10-20
Silver nanowire transparent electrodes have shown considerable potential to replace conventional transparent conductive materials. However, in this report we show that Joule heating is a unique and serious problem with these electrodes. When conducting current densities encountered in organic solar cells, the average surface temperature of indium tin oxide (ITO) and silver nanowire electrodes, both with sheet resistances of 60 ohms/square, remains below 35 °C. However, in contrast to ITO, the temperature in the nanowire electrode is very non-uniform, with some localized points reaching temperatures above 250 °C. These hotspots accelerate nanowire degradation, leading to electrode failure after 5 days of continuous current flow. We show that graphene, a commonly used passivation layer for these electrodes, slows nanowire degradation and creates a more uniform surface temperature under current flow. However, the graphene does not prevent Joule heating in the nanowires and local points of high temperature ultimately shift the failure mechanism from nanowire degradation to melting of the underlying plastic substrate. In this paper, surface temperature mapping, lifetime testing under current flow, post-mortem analysis, and modelling illuminate the behaviour and failure mechanisms of nanowires under extended current flow and provide guidelines for managing Joule heating.
The Joule heating problem in silver nanowire transparent electrodes
NASA Astrophysics Data System (ADS)
Khaligh, H. H.; Xu, L.; Khosropour, A.; Madeira, A.; Romano, M.; Pradére, C.; Tréguer-Delapierre, M.; Servant, L.; Pope, M. A.; Goldthorpe, I. A.
2017-10-01
Silver nanowire transparent electrodes have shown considerable potential to replace conventional transparent conductive materials. However, in this report we show that Joule heating is a unique and serious problem with these electrodes. When conducting current densities encountered in organic solar cells, the average surface temperature of indium tin oxide (ITO) and silver nanowire electrodes, both with sheet resistances of 60 ohms/square, remains below 35 °C. However, in contrast to ITO, the temperature in the nanowire electrode is very non-uniform, with some localized points reaching temperatures above 250 °C. These hotspots accelerate nanowire degradation, leading to electrode failure after 5 days of continuous current flow. We show that graphene, a commonly used passivation layer for these electrodes, slows nanowire degradation and creates a more uniform surface temperature under current flow. However, the graphene does not prevent Joule heating in the nanowires and local points of high temperature ultimately shift the failure mechanism from nanowire degradation to melting of the underlying plastic substrate. In this paper, surface temperature mapping, lifetime testing under current flow, post-mortem analysis, and modelling illuminate the behaviour and failure mechanisms of nanowires under extended current flow and provide guidelines for managing Joule heating.
Exact solution of two phase spherical Stefan problem with two free boundaries
NASA Astrophysics Data System (ADS)
Kavokin, Alexey A.; Nauryz, Targyn; Bizhigitova, Nazerke T.
2016-08-01
Solution of the heat equation in a spherical domain with two free boundaries (two-phase Stefan problem) when one of the subdomains degenerates at the initial time is considered. The use of conventional finite-difference methods in these cases is not expedient because of the degenerate domain. The solution is found in the form of combination of Integral Error functions series, [M. Sarsengeldin, and S. Kharin, Filomat, (2016), (in Press)] and then recurrent solvability of nonlinear algebraic equations for determining the coefficients of the series is proved. Such problems are of practical interest for the simulation of laser material processing as well for the modeling of thermal effects of electric arc that ignites during the opening of electric contacts [S. N. Kharin, and M. Sarsengeldin, ï£¡Influence of contact materials on phenomena in a short electrical arcï£¡, in Key Engineering Materials, Trans tech publications, Islamabad, Pakistan, 2012, pp. 321-329].
North Dakota's Centennial Quilt and Problem Solvers: Solutions: The Library Problem
ERIC Educational Resources Information Center
Small, Marian
2010-01-01
Quilt investigations, such as the Barn quilt problem in the December 2008/January 2009 issue of "Teaching Children Mathematics" and its solutions in last month's issue, can spark interdisciplinary pursuits for teachers and exciting connections for the full range of elementary school students. This month, North Dakota's centennial quilt…
Mapping solutions to an early multiplication word problem
NASA Astrophysics Data System (ADS)
Watson, Jane M.; Mulligan, Joanne
1990-06-01
Children's solutions to a variety of multiplication and division word problems were analysed in a cross-sectional pilot study of 34 children from Grades K to 2. Responses indicated a wide range of strategies used and these were further classified into developmental levels of strategy use. Because these data reflected the SOLO Taxonomy developmental model for classifying responses, a SOLO mapping procedure was used for further analysis. In this paper, the mapping procedure is applied to only one multiplication problem strategy, repeated addition, to exemplify the procedure. The mapping device employed in the analysis isolated three components of the problem-solving procedure: the cues given by the problem, the concepts and processes used by the children, and the responses given by the children. Responses to mathematical problems from children in this age group have not previously been used to elucidate the earlier modes of functioning in the SOLO Taxonomy. In particular this paper considers the Ikonic mode and the transition into the concrete Symbolic mode.
Numerical Solution of the k-Eigenvalue Problem
NASA Astrophysics Data System (ADS)
Hamilton, Steven Paul
2011-12-01
Obtaining solutions to the k-eigenvalue form of the radiation transport equation is an important topic in the design and analysis of nuclear reactors. Although this has been an area of active interest in the nuclear engineering community for several decades, to date no truly satisfactory solution strategies exist. In general, existing techniques are either slow to converge for difficult problems or suffer from stability and robustness issues that can cause solvers to diverge for some problems. This work provides a comparison between a variety of methods and introduces a new strategy based on the Davidson method that has been used in other fields for many years but never for this problem. The Davidson method offers an alternative to the nested iteration structure inherent to standard approaches and allows expensive linear solvers to be replaced by a potentially cheap preconditioner. To fill the role of this preconditioner, a strategy based on a multigrid treatment of the energy variable is developed. Numerical experiments using the 2-D NEWT transport package are presented, demonstrating the effectiveness of the proposed strategy.
Novel Problem Solving - The NASA Solution Mechanism Guide
NASA Technical Reports Server (NTRS)
Keeton, Kathryn E.; Richard, Elizabeth E.; Davis, Jeffrey R.
2014-01-01
Over the past five years, the Human Health and Performance (HH&P) Directorate at the NASA Johnson Space Center (JSC) has conducted a number of pilot and ongoing projects in collaboration and open innovation. These projects involved the use of novel open innovation competitions that sought solutions from "the crowd", non-traditional problem solvers. The projects expanded to include virtual collaboration centers such as the NASA Human Health and Performance Center (NHHPC) and more recently a collaborative research project between NASA and the National Science Foundation (NSF). These novel problem-solving tools produced effective results and the HH&P wanted to capture the knowledge from these new tools, to teach the results to the directorate, and to implement new project management tools and coursework. The need to capture and teach the results of these novel problem solving tools, the HH&P decided to create a web-based tool to capture best practices and case studies, to teach novice users how to use new problem solving tools and to change project management training/. This web-based tool was developed with a small, multi-disciplinary group and named the Solution Mechanism Guide (SMG). An alpha version was developed that was tested against several sessions of user groups to get feedback on the SMG and determine a future course for development. The feedback was very positive and the HH&P decided to move to the beta-phase of development. To develop the web-based tool, the HH&P utilized the NASA Tournament Lab (NTL) to develop the software with TopCoder under an existing contract. In this way, the HH&P is using one new tool (the NTL and TopCoder) to develop the next generation tool, the SMG. The beta-phase of the SMG is planed for release in the spring of 2014 and results of the beta-phase testing will be available for the IAC meeting in September. The SMG is intended to disrupt the way problem solvers and project managers approach problem solving and to increase the
MAST solution of advection problems in irrotational flow fields
NASA Astrophysics Data System (ADS)
Aricò, Costanza; Tucciarelli, Tullio
2007-03-01
A new numerical-analytical Eulerian procedure is proposed for the solution of convection-dominated problems in the case of existing scalar potential of the flow field. The methodology is based on the conservation inside each computational elements of the 0th and 1st order effective spatial moments of the advected variable. This leads to a set of small ODE systems solved sequentially, one element after the other over all the computational domain, according to a MArching in Space and Time technique. The proposed procedure shows the following advantages: (1) it guarantees the local and global mass balance; (2) it is unconditionally stable with respect to the Courant number, (3) the solution in each cell needs information only from the upstream cells and does not require wider and wider stencils as in most of the recently proposed higher-order methods; (4) it provides a monotone solution. Several 1D and 2D numerical test have been performed and results have been compared with analytical solutions, as well as with results provided by other recent numerical methods.
Light Pollution: the Problem and the Potential Solutions
NASA Astrophysics Data System (ADS)
Crawford, David L.
Essentially all astronomical observing sites have been adversely affected by light pollution, the increasing sky glow above all cities worldwide. Those sites not now affected will be in time. There is no getting away from it. This sky glow is decreasing the value of our observing facilities, and several observatories have been compromised to the extent that ``dark sky" astronomy is no longer possible. Furthermore, this sky glow is also affecting almost all amateur astronomy and the general public, removing much of the universe from the view of us all. The change in only one generation is remarkable. Something must be done. Fortunately, there are solutions. They have been implemented to some extent in a number of locations, and we know they work. The problem is in building awareness of the issues and of the solutions and then in overcoming the apathy of most people, including astronomers, to do something to help implement the solutions. We are fortunate in that all of these solutions help to improve greatly the quality of our outdoor nighttime lighting, improving visibility, removing glare, saving energy and increasing the ambience of the nighttime environment. We can all win, and we must.
Solution to certain problems in the failure of composite structures
NASA Astrophysics Data System (ADS)
Goodsell, Johnathan
The present work contains the solution of two problems in composite structures. In the first, an approximate elasticity solution for prediction of the displacement, stress and strain fields within the m-layer, symmetric and balanced angle-ply composite laminate of finite-width subjected anticlastic bending deformation is developed. The solution is shown to recover classical laminated plate theory predictions at interior regions of the laminate and thereby illustrates the boundary layer character of this interlaminar phenomenon. The results exhibit the anticipated response in congruence with the solutions for uniform axial extension and uniform temperature change, where divergence of the interlaminar shearing stress is seen to occur at the intersection of the free-edge and planes between lamina of +theta and -theta orientation. The analytical results show excellent agreement with the finite-element predictions for the same boundary-value problem and thereby provide an efficient and compact solution available for parametric studies of the influence of geometry and material properties. The solution is combined with previously developed solutions for uniform axial extension and uniform temperature change of the identical laminate and the combined solution is exercised to compare the relative magnitudes of free-edge phenomenon arising from the different loading conditions, to study very thick laminates and laminates where the laminate width is less than the laminate thickness. Significantly, it was demonstrated that the solution is valid for arbitrary stacking sequence and the solution was exercised to examine antisymmetric and non-symmetric laminates. Finally, the solution was exercised to determine the dimensions of the boundary layer for very large numbers of layers. It was found that the dimension of the boundary layer width in bending is approximately twice that in uniform axial extension and uniform temperature change. In the second, the intrinsic flaw concept is
Technology Solutions Case Study: Foundation Heat Exchanger, Oak Ridge, Tennessee
2014-03-01
The foundation heat exchanger, developed by Oak Ridge National Laboratory, is a new concept for a cost-effective horizontal ground heat exchanger that can be connected to water-to-water or water-to-air heat pump systems for space conditioning as well as domestic water heating.
Problems and Solutions of Popularization of Accounting Computerization
NASA Astrophysics Data System (ADS)
Lu, Kan; Fu, YingLi; Gu, CaiDong; Zhang, Liang
With the integration of China's economy and international markets, accounting computerization, which conducts accounting and accounting control by taking advantage of computer, has become a major component sector of accounting modernization and the main content of accounting reform. The popularization of accounting computerization is beyond question. Only this popularization can meet the requirement of knowledge economy for accounting information. It is the need to deepen accounting reform, to further enhance the level of accounting work and to achieve China's modernization of science and technology as well. This paper discusses problems and relevant solutions in the popularization process of accounting computerization so as to carry out this popularization better.
New discretization and solution techniques for incompressible viscous flow problems
NASA Technical Reports Server (NTRS)
Gunzburger, M. D.; Nicolaides, R. A.; Liu, C. H.
1983-01-01
Several topics arising in the finite element solution of the incompressible Navier-Stokes equations are considered. Specifically, the question of choosing finite element velocity/pressure spaces is addressed, particularly from the viewpoint of achieving stable discretizations leading to convergent pressure approximations. The role of artificial viscosity in viscous flow calculations is studied, emphasizing work by several researchers for the anisotropic case. The last section treats the problem of solving the nonlinear systems of equations which arise from the discretization. Time marching methods and classical iterative techniques, as well as some modifications are mentioned.
Problems and solutions of the IFSMTF power and switch system
Wood, R.J.; Wintenberg, R.E.; Googe, J.M.; Nickels, L.E.
1985-01-01
Solutions have been found for the problems encountered with the coil power and switching systems of the International Fusion Superconducting Magnet Test Facility (IFSMTF). The coil power system provides the filtered dc sources (+- 12 V dc; 25,000 A) for charging and discharging the coils of the IFSMTF experiment. The switching system provides the means of transferring the coil current into a dump resistor when a rapid discharge of a coil is required due to a coil failure (quench) or other system abnormalities.
Building Science and Technology Solutions for National Problems
Bishop, Alan R.
2012-06-05
The nation's investment in Los Alamos has fostered scientific capabilities for national security missions. As the premier national security science laboratory, Los Alamos tackles: (1) Multidisciplinary science, technology, and engineering challenges; (2) Problems demanding unique experimental and computational facilities; and (3) Highly complex national security issues requiring fundamental breakthroughs. Our mission as a DOE national security science laboratory is to develop and apply science, technology, and engineering solutions that: (1) ensure the safety, security, and reliability of the US nuclear deterrent; (2) protect against the nuclear threat; and (3) solve national security challenges.
Multidimensional assessment of criminal recidivism: problems, pitfalls, and proposed solutions.
Vrieze, Scott I; Grove, William M
2010-06-01
All states have statutes in place to civilly commit individuals at high risk for violence. The authors address difficulties in assessing such risk but use as an example the task of predicting sexual violence recidivism; the principles espoused here generalize to predicting all violence. As part of the commitment process, mental health professionals, who are often psychologists, evaluate an individual's risk of sexual recidivism. It is common for professionals conducting these risk assessments to use several actuarial risk prediction instruments (i.e., psychological tests). These tests rarely demonstrate close agreement in the risk figures they provide. Serious epistemological and psychometric problems in the multivariate assessment of recidivism risk are pointed out. Sound psychometric, or in some cases heuristic, solutions to these problems are proffered, in the hope of improving clinical practice. The authors focus on how to make these tests' outputs commensurable and discuss various ways to combine them in coherent, justifiable fashions.
Finite element solution of optimal control problems with inequality constraints
NASA Technical Reports Server (NTRS)
Bless, Robert R.; Hodges, Dewey H.
1990-01-01
A finite-element method based on a weak Hamiltonian form of the necessary conditions is summarized for optimal control problems. Very crude shape functions (so simple that element numerical quadrature is not necessary) can be used to develop an efficient procedure for obtaining candidate solutions (i.e., those which satisfy all the necessary conditions) even for highly nonlinear problems. An extension of the formulation allowing for discontinuities in the states and derivatives of the states is given. A theory that includes control inequality constraints is fully developed. An advanced launch vehicle (ALV) model is presented. The model involves staging and control constraints, thus demonstrating the full power of the weak formulation to date. Numerical results are presented along with total elapsed computer time required to obtain the results. The speed and accuracy in obtaining the results make this method a strong candidate for a real-time guidance algorithm.
Exact solutions for semirelativistic problems with non-local potentials
NASA Astrophysics Data System (ADS)
Hall, Richard L.
2006-01-01
It is shown that exact solutions may be found for the energy eigenvalue problem generated by the class of semirelativistic Hamiltonians of the form H = \\sqrt{m^2+p^2} + \\hat{V} , where \\hat{V} is a non-local potential with a separable kernel of the form {\\cal V}(r,r^{\\prime}) = - \\sum_{i=1}^n v_i f_i(r)g_i(r^{\\prime}) . Explicit examples in one and three dimensions are discussed, including the Yamaguchi and Gauss potentials. The results are used to obtain lower bounds for the energy of the corresponding N-boson problem, with upper bounds provided by the use of a Gaussian trial function.
Finite element solution of optimal control problems with inequality constraints
NASA Technical Reports Server (NTRS)
Bless, Robert R.; Hodges, Dewey H.
1990-01-01
A finite-element method based on a weak Hamiltonian form of the necessary conditions is summarized for optimal control problems. Very crude shape functions (so simple that element numerical quadrature is not necessary) can be used to develop an efficient procedure for obtaining candidate solutions (i.e., those which satisfy all the necessary conditions) even for highly nonlinear problems. An extension of the formulation allowing for discontinuities in the states and derivatives of the states is given. A theory that includes control inequality constraints is fully developed. An advanced launch vehicle (ALV) model is presented. The model involves staging and control constraints, thus demonstrating the full power of the weak formulation to date. Numerical results are presented along with total elapsed computer time required to obtain the results. The speed and accuracy in obtaining the results make this method a strong candidate for a real-time guidance algorithm.
Method of approximation of the weak solution of elasticity problems
NASA Astrophysics Data System (ADS)
Anoufriev, Igor E.; Petukhov, Leonid V.
1999-05-01
Let tT be a bounded 3D domain with Lipschitz boundary (Gamma) , (sigma) equals (pi) R 2 is a prescribed displacement on (Gamma) (volume forces are absent). We denote by A(u,v) equals integral(Omega ) L(epsilon) (u) (DOT) (epsilon) (v) dx bilinear form corresponding to the first elasticity problem where L is a tensor of Hooke's law written in the tensor form (sigma) equals L(epsilon) (isotropic case will be the subject of consideration) and by V a subspace of Sobolev space W21((Omega) ,R3) that is V equals {v equalsV W21((Omega) ,R3) v equals 0 on (Gamma) }. We assume that gi equalsV W21/2((Gamma) ) and A(u,v) is V-elliptic bilinear form. A weak solution of the first elasticity problem is a vector- valued function.
Multidimensional Assessment of Criminal Recidivism: Problems, Pitfalls, and Proposed Solutions
Vrieze, Scott I.; Grove, William M.
2010-01-01
All states have statutes in place to commit civilly individuals at high risk for violence. This note addresses difficulties in assessing such risk, but uses as an example the task of predicting sexual violence recidivism; the principles espoused here generalize to predicting all violence. As part of commitment process, mental health professionals, who are often psychologists, evaluate an individual’s risk of sexual recidivism. It is common for professionals conducting these risk assessments to use several actuarial risk prediction instruments (i.e., psychological tests). These tests rarely agree closely in the risk figures they provide. Serious epistemological and psychometric problems in the multivariate assessment of recidivism risk are pointed out. Sound psychometric, or in some cases heuristic, solutions to these problems are proffered, in hope of improving clinical practice. We focus on how to make these tests’ outputs commensurable, and discuss various ways to combine them in coherent, justifiable, fashions. PMID:20528065
Doebling, Scott William
2016-10-22
This paper documents the escape of high explosive (HE) products problem. The problem, first presented by Fickett & Rivard, tests the implementation and numerical behavior of a high explosive detonation and energy release model and its interaction with an associated compressible hydrodynamics simulation code. The problem simulates the detonation of a finite-length, one-dimensional piece of HE that is driven by a piston from one end and adjacent to a void at the other end. The HE equation of state is modeled as a polytropic ideal gas. The HE detonation is assumed to be instantaneous with an infinitesimal reaction zone. Viamore » judicious selection of the material specific heat ratio, the problem has an exact solution with linear characteristics, enabling a straightforward calculation of the physical variables as a function of time and space. Lastly, implementation of the exact solution in the Python code ExactPack is discussed, as are verification cases for the exact solution code.« less
Skeletal muscle mechanics: questions, problems and possible solutions.
Herzog, Walter
2017-09-16
Skeletal muscle mechanics have been studied ever since people have shown an interest in human movement. However, our understanding of muscle contraction and muscle mechanical properties has changed fundamentally with the discovery of the sliding filament theory in 1954 and associated cross-bridge theory in 1957. Nevertheless, experimental evidence suggests that our knowledge of the mechanisms of contraction is far from complete, and muscle properties and muscle function in human movement remain largely unknown.In this manuscript, I am trying to identify some of the crucial challenges we are faced with in muscle mechanics, offer possible solutions to questions, and identify problems that might be worthwhile exploring in the future. Since it is impossible to tackle all (worthwhile) problems in a single manuscript, I identified three problems that are controversial, important, and close to my heart. They may be identified as follows: (i) mechanisms of muscle contraction, (ii) in vivo whole muscle mechanics and properties, and (iii) force-sharing among synergistic muscles. These topics are fundamental to our understanding of human movement and movement control, and they contain a series of unknowns and challenges to be explored in the future.It is my hope that this paper may serve as an inspiration for some, may challenge current beliefs in selected areas, tackle important problems in the area of muscle mechanics, physiology and movement control, and may guide and focus some of the thinking of future muscle mechanics research.
Intracanal use of heated rinsing solutions: A pilot study.
Sonntag, David; Raab, Wolfgang H-M; Martin, Evelyn; Keppel, Ralf
2017-01-01
The tissue-dissolving and bactericidal activity of sodium hypochlorite (NaOCl) can be increased by warming the NaOCl solution without concurrently increasing its toxicity. The present study was set up to determine if and to what extent a heated liquid reaches the apical region. A temperature sensor was introduced from the apical aspect into a human canine 22 mm in length prepared to size 40.04. At 37°C in the incubator the canal was irrigated with water 10 times each at temperatures of 10°C, 21°C, 45°C, 60°C, and 37°C (control group). The apical temperature curve was recorded with a one-second resolution from the time the irrigation started until at least 2 minutes after its end. None of the measurements yielded the same temperature in the apical region as that of the coronally introduced liquid. At 60°C, a maximum value of 52.2°C ± 1.39°C, and at 10°C, a minimum value of 16.09°C ± 0.39°C, was achieved apically. At 1 minute after the end of active rinse cycle, the temperature at the apical probe differed only 4.8°C to 0.9°C ± 1.41°C from the initial value (about 37°C). Only with the cold 10°C solution was the temperature difference higher, at 7.5°C ± 2.14°C. The benefit of heating irrigants accrues primarily during the period of active rinsing; immediately after the end of the rinsing cycle, body temperature is reached again. A positive aspect to be noted is that an irrigant stored at room temperature is quickly warmed to 37°C in the root canal by the temperature of the body.
Exploiting New Features of COMSOL Version 4 on Conjugate Heat Transfer Problems
Freels, James D; Arimilli, Rao V; Bodey, Isaac T
2010-01-01
Users of COMSOL Multiphysics at version 3.5a and earlier have enjoyed many features that have provided not only a good user experience at the GUI interface, but also the capability to solve many classes of problems in a consistent manner with the physics being simulated. With the new release version 4.0 and later (4+) of COMSOL, the user is provided a dramatic new interface from which to interact, and many new features ``under the hood'' for solving problems more efficiently and with even greater accuracy and consistency than before. This paper will explore several of these new version 4+ features for the conjugate heat transfer class of problems. Our environment is challenging in that we demand high-quality solutions for nuclear-reactor systems and the models tend to become large and difficult to solve. Areas investigated include turbulence modeling, distributed parallel processing, solver scaling, and opengl graphics issues in a Linux computing environment.
Application of program generation technology in solving heat and flow problems
NASA Astrophysics Data System (ADS)
Wan, Shui; Wu, Bangxian; Chen, Ningning
2007-05-01
Based on a new DIY concept for software development, an automatic program-generating technology attached on a software system called as Finite Element Program Generator (FEPG) provides a platform of developing programs, through which a scientific researcher can submit his special physico-mathematical problem to the system in a more direct and convenient way for solution. For solving flow and heat problems by using finite element method, the stabilization technologies and fraction-step methods are adopted to overcome the numerical difficulties caused mainly due to the dominated convection. A couple of benchmark problems are given in this paper as examples to illustrate the usage and the superiority of the automatic program generation technique, including the flow in a lid-driven cavity, the starting flow in a circular pipe, the natural convection in a square cavity, and the flow past a circular cylinder, etc. They are also shown as the verification of the algorithms.
ULTRA-SHARP solution of the Smith-Hutton problem
NASA Technical Reports Server (NTRS)
Leonard, B. P.; Mokhtari, Simin
1992-01-01
Highly convective scalar transport involving near-discontinuities and strong streamline curvature was addressed in a paper by Smith and Hutton in 1982, comparing several different convection schemes applied to a specially devised test problem. First order methods showed significant artificial diffusion, whereas higher order methods gave less smearing but had a tendency to overshoot and oscillate. Perhaps because unphysical oscillations are more obvious than unphysical smearing, the intervening period has seen a rise in popularity of low order artificially diffusive schemes, especially in the numerical heat transfer industry. The present paper describes an alternate strategy of using non-artificially diffusive high order methods, while maintaining strictly monotonic transitions through the use of simple flux limited constraints. Limited third order upwinding is usually found to be the most cost effective basic convection scheme. Tighter resolution of discontinuities can be obtained at little additional cost by using automatic adaptive stencil expansion to higher order in local regions, as needed.
ULTRA-SHARP solution of the Smith-Hutton problem
NASA Astrophysics Data System (ADS)
Leonard, B. P.; Mokhtari, Simin
1992-02-01
Highly convective scalar transport involving near-discontinuities and strong streamline curvature was addressed in a paper by Smith and Hutton in 1982, comparing several different convection schemes applied to a specially devised test problem. First order methods showed significant artificial diffusion, whereas higher order methods gave less smearing but had a tendency to overshoot and oscillate. Perhaps because unphysical oscillations are more obvious than unphysical smearing, the intervening period has seen a rise in popularity of low order artificially diffusive schemes, especially in the numerical heat transfer industry. The present paper describes an alternate strategy of using non-artificially diffusive high order methods, while maintaining strictly monotonic transitions through the use of simple flux limited constraints. Limited third order upwinding is usually found to be the most cost effective basic convection scheme. Tighter resolution of discontinuities can be obtained at little additional cost by using automatic adaptive stencil expansion to higher order in local regions, as needed.
Character analysis in morphological phylogenetics: problems and solutions.
Wiens, J J
2001-01-01
Many aspects of morphological phylogenetics are controversial in the theoretical systematics literature and yet are often poorly explained and justified in empirical studies. In this paper, I argue that most morphological characters describe variation that is fundamentally quantitative, regardless of whether they are coded qualitatively or quantitatively by systematists. Given this view, three fundamental problems in morphological character analysis (definition, delimitation, and ordering of character states) may have a common solution: coding morphological characters as continuous quantitative traits. A new parsimony method (step-matrix gap-weighting, a modification of Thiele's approach) is proposed that allows quantitative traits to be analyzed as continuous variables. The problem of scaling or weighting quantitative characters relative to qualitative characters (and to each other) is reviewed, and three possible solutions are described. The new coding method is applied to data from hoplocercid lizards, and the results show the sensitivity of phylogenetic conclusions to different scaling methods. Although some authors reject the use of continuous, overlapping, quantitative characters in phylogenetic analysis, quantitative data from hoplocercid lizards that are coded using the new approach contain significant phylogenetic structure and exhibit levels of homoplasy similar to those seen in data that are coded qualitatively.
Comet solutions to a stylized BWR benchmark problem
Zhang, D.; Rahnema, F.
2012-07-01
In this paper, a stylized 3-D BWR benchmark problem was used to evaluate the performance of the coarse mesh radiation transport method COMET. The benchmark problem consists of 560 fuel bundles at 3 different burnups and 3 coolant void states. The COMET solution was compared with the corresponding Monte Carlo reference solution using the same 2-group material cross section library for three control blade (rod) configurations, namely, all rods out (ARO), all rods in (ARI) and some rods in (SRJ). The differences in the COMET and MCNP eigenvalues were 43 pcm, 66 pcm and 32 pcm for the ARO, ARI and SRI cases, respectively. These differences are all within 3 standard deviations of the COMET uncertainty. The average relative differences in the bundle averaged fission densities for these three cases were 0.89%, 1.24%, and 1.05%, respectively. The corresponding differences in the fuel pin averaged fission densities were 1.24%, 1.84% and 1.29%, respectively. It was found that COMET is 3,000 times faster than Monte Carlo, while its statistical uncertainty in the fuel pin fission density is much lower than that of Monte Carlo (i.e., {approx}40 times lower). (authors)
Exact and Approximate Stability of Solutions to Traveling Salesman Problems.
Niendorf, Moritz; Girard, Anouck R
2017-01-17
This paper presents the stability analysis of an optimal tour for the symmetric traveling salesman problem (TSP) by obtaining stability regions. The stability region of an optimal tour is the set of all cost changes for which that solution remains optimal and can be understood as the margin of optimality for a solution with respect to perturbations in the problem data. It is known that it is not possible to test in polynomial time whether an optimal tour remains optimal after the cost of an arbitrary set of edges changes. Therefore, this paper develops tractable methods to obtain under and over approximations of stability regions based on neighborhoods and relaxations. The application of the results to the two-neighborhood and the minimum 1 tree (M1T) relaxation are discussed in detail. For Euclidean TSPs, stability regions with respect to vertex location perturbations and the notion of safe radii and location criticalities are introduced. Benefits of this paper include insight into robustness properties of tours, minimum spanning trees, M1Ts, and fast methods to evaluate optimality after perturbations occur. Numerical examples are given to demonstrate the methods and achievable approximation quality.
C. AVILES-RAMOS; C. RUDY
2000-11-01
The transient exact solution of heat conduction in a two-domain composite cylinder is developed using the separation of variables technique. The inner cylinder is isotropic and the outer cylindrical layer is orthotropic. Temperature solutions are obtained for boundary conditions of the first and second kinds at the outer surface of the orthotropic layer. These solutions are applied to heat flow calorimeters modeling assuming that there is heat generation due to nuclear reactions in the inner cylinder. Heat flow calorimeter simulations are carried out assuming that the inner cylinder is filled with plutonium oxide powder. The first objective in these simulations is to predict the onset of thermal equilibrium of the calorimeter with its environment. Two types of boundary conditions at the outer surface of the orthotropic layer are used to predict thermal equilibrium. The procedure developed to carry out these simulations can be used as a guideline for the design of calorimeters. Another important application of these solutions is on the estimation of thermophysical properties of orthotropic cylinders. The thermal conductivities in the vertical, radial and circumferential directions of the orthotropic outer layer can be estimated using this exact solution and experimental data. Simultaneous estimation of the volumetric heat capacity and thermal conductivities is also possible. Furthermore, this solution has potential applications to the solution of the inverse heat conduction problem in this cylindrical geometry. An interesting feature of the construction of this solution is that two different sets of eigenfunctions need to be considered in the eigenfunction expansion. These eigenfunctions sets depend on the relative values of the thermal diffusivity of the inner cylinder and the thermal diffusivity in the vertical direction of the outer cylindrical layer.
Datyner, N B; Cohen, I S
1991-11-01
We provide a theoretical framework for the estimation of the performance of a modular cooling/heating device for tissue baths. The framework can be adapted to other designs using Peltier elements for cooling and heating. The design employs a Peltier as a heat pump and a flat heat pipe to transport heat to or from a 'remote' site. In the cooling mode heat from the hot side of the Peltier is removed by a heat sink cooled by a fan. The small cross section of the heat pipe permits cooling/heating of tissue chambers on microscope stages or in locations where it would be impractical to mount a Peltier element. The faces of the heat pipe can be used to pre-cool/heat solutions using a simple capillary heat exchanger.
Stationary solutions in a model three-body problem
NASA Astrophysics Data System (ADS)
Zlenko, A. A.
2016-12-01
Two visco-elastic bodies (deformable spheres) are considered which interact with each other and move in quasi-circular orbits in the attractive force field of a fixed centre - a heavy point mass. Their axes of rotation are perpendicular to their orbital plane. Stationary solutions of the evolutionary equations of motion are found. In one particular case, they extend solutions of the restricted circular three-body problem corresponding to two collinear libration points. All three bodies are located along a straight line. This implies synchronization of motion of the barycentre of the two visco-elastic bodies relative to the attracting centre with their orbital motion relative to the barycentre in a 1:1 resonance. The rotation of the two bodies relative to their own centres of mass takes place in such a way that the bodies "view" the attracting centre and each other from the same side, i.e., they are synchronized in a 1:1 resonance with their orbital motion. Instability of stationary solutions is analytically proven.
Stability of Solutions to Classes of Traveling Salesman Problems.
Niendorf, Moritz; Kabamba, Pierre T; Girard, Anouck R
2016-04-01
By performing stability analysis on an optimal tour for problems belonging to classes of the traveling salesman problem (TSP), this paper derives margins of optimality for a solution with respect to disturbances in the problem data. Specifically, we consider the asymmetric sequence-dependent TSP, where the sequence dependence is driven by the dynamics of a stack. This is a generalization of the symmetric non sequence-dependent version of the TSP. Furthermore, we also consider the symmetric sequence-dependent variant and the asymmetric non sequence-dependent variant. Amongst others these problems have applications in logistics and unmanned aircraft mission planning. Changing external conditions such as traffic or weather may alter task costs, which can render an initially optimal itinerary suboptimal. Instead of optimizing the itinerary every time task costs change, stability criteria allow for fast evaluation of whether itineraries remain optimal. This paper develops a method to compute stability regions for the best tour in a set of tours for the symmetric TSP and extends the results to the asymmetric problem as well as their sequence-dependent counterparts. As the TSP is NP-hard, heuristic methods are frequently used to solve it. The presented approach is also applicable to analyze stability regions for a tour obtained through application of the k -opt heuristic with respect to the k -neighborhood. A dimensionless criticality metric for edges is proposed, such that a high criticality of an edge indicates that the optimal tour is more susceptible to cost changes in that edge. Multiple examples demonstrate the application of the developed stability computation method as well as the edge criticality measure that facilitates an intuitive assessment of instances of the TSP.
A solution to lithium problem by long-lived stau
NASA Astrophysics Data System (ADS)
Sato, Joe; Shimomura, Takashi; Yamanaka, Masato
We review a nonstandard Big-Bang Nucleosynthesis (BBN) scenario within the minimal supersymmetric standard model, and propose an idea to solve both the 7Li and 6Li problems. Each problem is a discrepancy between the predicted abundance in the standard BBN and observed one. We focus on the stau, a supersymmetric partner of tau lepton, which is a long-lived charged particle when it is the next lightest supersymmetric particle and is degenerate in mass with the lightest supersymmetric particle. The long-lived stau forms a bound state with a nucleus, and provides nonstandard nuclear reactions. One of those, the internal conversion process, accelerates the destruction of 7Be and 7Li, and leads to a solution to the 7Li problem. On the other hand, the bound state of the stau and 4He enhances productions of n, D, T and 6Li. The over-production of 6Li could solve the 6Li problem; while the over-productions of D and T could conflict with observations, and hence the relevant parameter space of the stau is strictly constrained. We therefore need to carefully investigate the stau-4He bound state to find a condition of solving the 6Li problem. The scenario of the long-lived stau simultaneously and successfully fits the abundances of light elements (D, T, 3He, 4He, 6Li and 7Li) and the neutralino dark matter to the observed ones. Consequently, the parameter space both of the stau and the neutralino is determined with excellent accuracy.
NASA Astrophysics Data System (ADS)
Aman, Sidra; Zuki Salleh, Mohd; Ismail, Zulkhibri; Khan, Ilyas
2017-09-01
This article focuses on the flow of Maxwell nanofluids with graphene nanoparticles over a vertical plate (static) with constant wall temperature. Possessing high thermal conductivity, engine oil is useful to be chosen as base fluid with free convection. The problem is modelled in terms of PDE’s with boundary conditions. Some suitable non-dimensional variables are interposed to transform the governing equations into dimensionless form. The generated equations are solved via Laplace transform technique. Exact solutions are evaluated for velocity and temperature. These solutions are significantly controlled by some parameters involved. Temperature rises with elevation in volume fraction while Velocity decreases with increment in volume fraction. A comparison with previous published results are established and discussed. Moreover, a detailed discussion is made for influence of volume fraction on the flow and heat profile.
1980-10-01
THE SOLUTION OF LINEAR COMPLEMENTARITY PROBLEMS ARISING FROM FREE BOUNDARY PROBLEMS Achi Brandt*’ ( 1 ) and Colin W. Cryer’ (2 1.1 INTRODUCTION...University of Wisconsin-Madison, Madison, Madison, WI 53706. ( 1 )Sponsored by the United States Army under Contract No. DAAG29-80-C-0041. (2)Sponsored by...multi- plying (1.3a) by - 1 . For example, if t is the Laplace operator in R 2 , then a possible choice for L would be the classical five-point difference
Dalir, Nemat
2014-01-01
An exact analytical solution is obtained for the problem of three-dimensional transient heat conduction in the multilayered sphere. The sphere has multiple layers in the radial direction and, in each layer, time-dependent and spatially nonuniform volumetric internal heat sources are considered. To obtain the temperature distribution, the eigenfunction expansion method is used. An arbitrary combination of homogenous boundary condition of the first or second kind can be applied in the angular and azimuthal directions. Nevertheless, solution is valid for nonhomogeneous boundary conditions of the third kind (convection) in the radial direction. A case study problem for the three-layer quarter-spherical region is solved and the results are discussed.
Dalir, Nemat
2014-01-01
An exact analytical solution is obtained for the problem of three-dimensional transient heat conduction in the multilayered sphere. The sphere has multiple layers in the radial direction and, in each layer, time-dependent and spatially nonuniform volumetric internal heat sources are considered. To obtain the temperature distribution, the eigenfunction expansion method is used. An arbitrary combination of homogenous boundary condition of the first or second kind can be applied in the angular and azimuthal directions. Nevertheless, solution is valid for nonhomogeneous boundary conditions of the third kind (convection) in the radial direction. A case study problem for the three-layer quarter-spherical region is solved and the results are discussed. PMID:27433511
Improved time-space method for 3-D heat transfer problems including global warming
Saitoh, T.S.; Wakashima, Shinichiro
1999-07-01
In this paper, the Time-Space Method (TSM) which has been proposed for solving general heat transfer and fluid flow problems was improved in order to cover global and urban warming. The TSM is effective in almost all-transient heat transfer and fluid flow problems, and has been already applied to the 2-D melting problems (or moving boundary problems). The computer running time will be reduced to only 1/100th--1/1000th of the existing schemes for 2-D and 3-D problems. However, in order to apply to much larger-scale problems, for example, global warming, urban warming and general ocean circulation, the SOR method (or other iterative methods) in four dimensions is somewhat tedious and provokingly slow. Motivated by the above situation, the authors improved the speed of iteration of the previous TSM by introducing the following ideas: (1) Timewise chopping: Time domain is chopped into small peaches to save memory requirement; (2) Adaptive iteration: Converged region is eliminated for further iteration; (3) Internal selective iteration: Equation with slow iteration speed in iterative procedure is selectively iterated to accelerate entire convergence; and (4) False transient integration: False transient term is added to the Poisson-type equation and the relevant solution is regarded as a parabolic equation. By adopting the above improvements, the higher-order finite different schemes and the hybrid mesh, the computer running time for the TSM is reduced to some 1/4600th of the conventional explicit method for a typical 3-D natural convection problem in a closed cavity. The proposed TSM will be more efficacious for large-scale environmental problems, such as global warming, urban warming and general ocean circulation, in which a tremendous computing time would be required.
Shumaker, D E; Woodward, C S
2005-05-03
In this paper, the authors investigate performance of a fully implicit formulation and solution method of a diffusion-reaction system modeling radiation diffusion with material energy transfer and a fusion fuel source. In certain parameter regimes this system can lead to a rapid conversion of potential energy into material energy. Accuracy in time integration is essential for a good solution since a major fraction of the fuel can be depleted in a very short time. Such systems arise in a number of application areas including evolution of a star and inertial confinement fusion. Previous work has addressed implicit solution of radiation diffusion problems. Recently Shadid and coauthors have looked at implicit and semi-implicit solution of reaction-diffusion systems. In general they have found that fully implicit is the most accurate method for difficult coupled nonlinear equations. In previous work, they have demonstrated that a method of lines approach coupled with a BDF time integrator and a Newton-Krylov nonlinear solver could efficiently and accurately solve a large-scale, implicit radiation diffusion problem. In this paper, they extend that work to include an additional heating term in the material energy equation and an equation to model the evolution of the reactive fuel density. This system now consists of three coupled equations for radiation energy, material energy, and fuel density. The radiation energy equation includes diffusion and energy exchange with material energy. The material energy equation includes reaction heating and exchange with radiation energy, and the fuel density equation includes its depletion due to the fuel consumption.
Singh, Brajesh K.; Srivastava, Vineet K.
2015-01-01
The main goal of this paper is to present a new approximate series solution of the multi-dimensional (heat-like) diffusion equation with time-fractional derivative in Caputo form using a semi-analytical approach: fractional-order reduced differential transform method (FRDTM). The efficiency of FRDTM is confirmed by considering four test problems of the multi-dimensional time fractional-order diffusion equation. FRDTM is a very efficient, effective and powerful mathematical tool which provides exact or very close approximate solutions for a wide range of real-world problems arising in engineering and natural sciences, modelled in terms of differential equations. PMID:26064639
Singh, Brajesh K; Srivastava, Vineet K
2015-04-01
The main goal of this paper is to present a new approximate series solution of the multi-dimensional (heat-like) diffusion equation with time-fractional derivative in Caputo form using a semi-analytical approach: fractional-order reduced differential transform method (FRDTM). The efficiency of FRDTM is confirmed by considering four test problems of the multi-dimensional time fractional-order diffusion equation. FRDTM is a very efficient, effective and powerful mathematical tool which provides exact or very close approximate solutions for a wide range of real-world problems arising in engineering and natural sciences, modelled in terms of differential equations.
NASA Astrophysics Data System (ADS)
Docktor, Jennifer L.; Dornfeld, Jay; Frodermann, Evan; Heller, Kenneth; Hsu, Leonardo; Jackson, Koblar Alan; Mason, Andrew; Ryan, Qing X.; Yang, Jie
2016-06-01
Problem solving is a complex process valuable in everyday life and crucial for learning in the STEM fields. To support the development of problem-solving skills it is important for researchers and curriculum developers to have practical tools that can measure the difference between novice and expert problem-solving performance in authentic classroom work. It is also useful if such tools can be employed by instructors to guide their pedagogy. We describe the design, development, and testing of a simple rubric to assess written solutions to problems given in undergraduate introductory physics courses. In particular, we present evidence for the validity, reliability, and utility of the instrument. The rubric identifies five general problem-solving processes and defines the criteria to attain a score in each: organizing problem information into a Useful Description, selecting appropriate principles (Physics Approach), applying those principles to the specific conditions in the problem (Specific Application of Physics), using Mathematical Procedures appropriately, and displaying evidence of an organized reasoning pattern (Logical Progression).
Multicluster solutions to a multinucleon problem and clustering phenomena
Gnilozub, I. A.; Kurgalin, S. D.; Tchuvil'sky, Yu. M.
2008-07-15
Various concepts of clustering phenomena are discussed. Precise multicluster solutions constructed by the present authors for an A-nucleon problem whose dynamical properties are described by a generalized Elliott Hamiltonian are used as a mathematical formalism of the theory of clustering phenomena in nuclei. It is shown that qualitative features of various clustering phenomena, such as the very fact of the existence of cluster states, their classification, and selectivity of reactions that populate them, are explained within the concept being discussed. The 2{alpha} + bineutron three-cluster states of the {sup 10}Be nucleus are classified, and their spectrum is calculated. It is demonstrated that the results of these calculations are in good agreement with experimental data.
A minimalist legislative solution to the problem of euthanasia.
Komesaroff, Paul A; Charles, Stephen
2015-05-18
Intense debate has continued for many years about whether voluntary euthanasia or assisted suicide should be permitted by law. The community is bitterly divided and there has been vigorous opposition from medical practitioners and the Australian Medical Association. Despite differences of religious and philosophical convictions and ethical values, there is widespread community agreement that people with terminal illnesses are entitled to adequate treatment, and should also be allowed to make basic choices about when and how they die. A problem with the current law is that doctors who follow current best practice cannot be confident that they will be protected from criminal prosecution. We propose simple changes to Commonwealth and state legislation that recognise community concerns and protect doctors acting in accordance with best current practice. This minimalist solution should be widely acceptable to the community, including both the medical profession and those who object to euthanasia for religious reasons. Important areas of disagreement will persist that can be addressed in future debates.
Numerical Solution of Some Types of Fractional Optimal Control Problems
Sweilam, Nasser Hassan; Al-Ajami, Tamer Mostafa; Hoppe, Ronald H. W.
2013-01-01
We present two different approaches for the numerical solution of fractional optimal control problems (FOCPs) based on a spectral method using Chebyshev polynomials. The fractional derivative is described in the Caputo sense. The first approach follows the paradigm “optimize first, then discretize” and relies on the approximation of the necessary optimality conditions in terms of the associated Hamiltonian. In the second approach, the state equation is discretized first using the Clenshaw and Curtis scheme for the numerical integration of nonsingular functions followed by the Rayleigh-Ritz method to evaluate both the state and control variables. Two illustrative examples are included to demonstrate the validity and applicability of the suggested approaches. PMID:24385874
Multicluster solutions to a multinucleon problem and clustering phenomena
NASA Astrophysics Data System (ADS)
Gnilozub, I. A.; Kurgalin, S. D.; Tchuvil'Sky, Yu. M.
2008-07-01
Various concepts of clustering phenomena are discussed. Precise multicluster solutions constructed by the present authors for an A-nucleon problem whose dynamical properties are described by a generalized Elliott Hamiltonian are used as a mathematical formalism of the theory of clustering phenomena in nuclei. It is shown that qualitative features of various clustering phenomena, such as the very fact of the existence of cluster states, their classification, and selectivity of reactions that populate them, are explained within the concept being discussed. The 2 α + bineutron three-cluster states of the 10Be nucleus are classified, and their spectrum is calculated. It is demonstrated that the results of these calculations are in good agreement with experimental data.
SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport
Langevin, Christian D.; Thorne, Daniel T.; Dausman, Alyssa M.; Sukop, Michael C.; Guo, Weixing
2008-01-01
The SEAWAT program is a coupled version of MODFLOW and MT3DMS designed to simulate three-dimensional, variable-density, saturated ground-water flow. Flexible equations were added to the program to allow fluid density to be calculated as a function of one or more MT3DMS species. Fluid density may also be calculated as a function of fluid pressure. The effect of fluid viscosity variations on ground-water flow was included as an option. Fluid viscosity can be calculated as a function of one or more MT3DMS species, and the program includes additional functions for representing the dependence on temperature. Although MT3DMS and SEAWAT are not explicitly designed to simulate heat transport, temperature can be simulated as one of the species by entering appropriate transport coefficients. For example, the process of heat conduction is mathematically analogous to Fickian diffusion. Heat conduction can be represented in SEAWAT by assigning a thermal diffusivity for the temperature species (instead of a molecular diffusion coefficient for a solute species). Heat exchange with the solid matrix can be treated in a similar manner by using the mathematically equivalent process of solute sorption. By combining flexible equations for fluid density and viscosity with multi-species transport, SEAWAT Version 4 represents variable-density ground-water flow coupled with multi-species solute and heat transport. SEAWAT Version 4 is based on MODFLOW-2000 and MT3DMS and retains all of the functionality of SEAWAT-2000. SEAWAT Version 4 also supports new simulation options for coupling flow and transport, and for representing constant-head boundaries. In previous versions of SEAWAT, the flow equation was solved for every transport timestep, regardless of whether or not there was a large change in fluid density. A new option was implemented in SEAWAT Version 4 that allows users to control how often the flow field is updated. New options were also implemented for representing constant
The PMHT: solutions for some of its problems
NASA Astrophysics Data System (ADS)
Wieneke, Monika; Koch, Wolfgang
2007-09-01
Tracking multiple targets in a cluttered environment is a challenging task. Probabilistic Multiple Hypothesis Tracking (PMHT) is an efficient approach for dealing with it. Essentially PMHT is based on the method of Expectation-Maximization for handling with association conflicts. Linearity in the number of targets and measurements is the main motivation for a further development and extension of this methodology. Unfortunately, compared with the Probabilistic Data Association Filter (PDAF), PMHT has not yet shown its superiority in terms of track-lost statistics. Furthermore, the problem of track extraction and deletion is apparently not yet satisfactorily solved within this framework. Four properties of PMHT are responsible for its problems in track maintenance: Non-Adaptivity, Hospitality, Narcissism and Local Maxima. 1, 2 In this work we present a solution for each of them and derive an improved PMHT by integrating the solutions into the PMHT formalism. The new PMHT is evaluated by Monte-Carlo simulations. A sequential Likelihood-Ratio (LR) test for track extraction has been developed and already integrated into the framework of traditional Bayesian Multiple Hypothesis Tracking. 3 As a multi-scan approach, also the PMHT methodology has the potential for track extraction. In this paper an analogous integration of a sequential LR test into the PMHT framework is proposed. We present an LR formula for track extraction and deletion using the PMHT update formulae. As PMHT provides all required ingredients for a sequential LR calculation, the LR is thus a by-product of the PMHT iteration process. Therefore the resulting update formula for the sequential LR test affords the development of Track-Before-Detect algorithms for PMHT. The approach is illustrated by a simple example.
Testable solution of the cosmological constant and coincidence problems
Shaw, Douglas J.; Barrow, John D.
2011-02-15
We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, {Lambda}, is linked to other observable properties of the Universe. This is achieved by promoting the CC from a parameter that must be specified, to a field that can take many possible values. The observed value of {Lambda}{approx_equal}(9.3 Gyrs){sup -2}[{approx_equal}10{sup -120} in Planck units] is determined by a new constraint equation which follows from the application of a causally restricted variation principle. When applied to our visible Universe, the model makes a testable prediction for the dimensionless spatial curvature of {Omega}{sub k0}=-0.0056({zeta}{sub b}/0.5), where {zeta}{sub b}{approx}1/2 is a QCD parameter. Requiring that a classical history exist, our model determines the probability of observing a given {Lambda}. The observed CC value, which we successfully predict, is typical within our model even before the effects of anthropic selection are included. When anthropic selection effects are accounted for, we find that the observed coincidence between t{sub {Lambda}={Lambda}}{sup -1/2} and the age of the Universe, t{sub U}, is a typical occurrence in our model. In contrast to multiverse explanations of the CC problems, our solution is independent of the choice of a prior weighting of different {Lambda} values and does not rely on anthropic selection effects. Our model includes no unnatural small parameters and does not require the introduction of new dynamical scalar fields or modifications to general relativity, and it can be tested by astronomical observations in the near future.
Solution of open region electromagnetic scattering problems on hypercube multiprocessors
Gedney, S.D.
1991-01-01
This thesis focuses on development of parallel algorithms that exploit hypercube multiprocessor computers for the solution of the scattering of electromagnetic fields by bodies situated in an unbounded space. Initially, algorithms based on the method of moments are investigated for coarse-grained MIMD hypercubes as well as finite-grained MIMD and SIMD hypercubes. It is shown that by exploiting the architecture of each hypercube, supercomputer performance can be obtained using the JPL Mark III hypercube and the Thinking Machine's CM2. Second, the use of the finite-element method for solution of the scattering by bodies of composite materials is presented. For finite bodies situated in an unbounded space, use of an absorbing boundary condition is investigated. A method known as the mixed-{chi} formulation is presented, which reduces the mesh density in the regions away from the scatterer, enhancing the use of an absorbing boundary condition. The scattering by troughs or slots is also investigated using a combined FEM/MoM formulation. This method is extended to the problem of the diffraction of electromagnetic waves by thick conducting and/or dielectric gratings. Finally, the adaptation of the FEM method onto a coarse-grained hypercube is presented.
Factors Influencing the Activity of Sterile Filtered and Heat-Sterilized Trypsin Solutions
Cook, R. A.; Poole, G. M.
1974-01-01
The mode of sterilization (filtration or heat) was found to significantly affect the activity of trypsin solutions. Trypsin activity was substantially reduced in the initial fractions of filtrate passed through asbestos filter pads; heat-sterilized trypsin was satisfactory for transfer of cell cultures grown on glass. Heat-sterilized trypsin may be useful when elimination of filterable organisms is required. PMID:4844278
An optical solution to the LGS spot elongation problem
NASA Astrophysics Data System (ADS)
Schreiber, Laura; Lombini, Matteo; Foppiani, Italo; Diolaiti, Emiliano; Conan, Jean-Marc; Marchetti, Enrico
2008-07-01
In the last years an increasing consideration has been given to the study of Laser Guide Stars (LGS) for the measurement of the disturbance introduced by the atmosphere. Due to the finite distance of the artificial reference source and its vertical extension (the Sodium layer occurs at approximately 90 km, with a vertical thickness of about 10 km), the source itself looks elongated, when observed from the edge of a large aperture. On a 40 m class telescope, for instance, the maximum elongation varies between 4 and 6 arcseconds, depending on the Sodium layer properties and on the launching position. This spot elongation strongly limits the performance of the most common wavefront sensors. A straightforward solution for a Shack-Hartmann wavefront sensor is to increase the laser power, in order to balance the loss of centroiding accuracy due to the elongation. This solution, although appealing in principle, presents drawbacks related, for instance, to the availability of very powerful lasers. We propose in this paper a wavefront sensor concept that provides an optical solution to the perspective elongation problem. It is based on an array of bi-prisms placed in the focal plane of a lenslet array; each bi-prism is aligned to the elongated spot produced by the corresponding lenslet; the spot is split into two beams, that are re-imaged into two micro-images of the sub-aperture itself; the difference in the integrated intensity of these two micro-images is proportional to the local wavefront slope. This method is sensitive only to the slope information in the direction locally orthogonal to the bi-prisms (and to the elongation) and the full information has to be recovered by combining the signals coming from different LGSs launched from different positions at the telescope edge. The pros and cons of this technique, in terms of hardware requirements and photon budget, are discussed in this paper.
The covariance matrix for the solution vector of an equality-constrained least-squares problem
NASA Technical Reports Server (NTRS)
Lawson, C. L.
1976-01-01
Methods are given for computing the covariance matrix for the solution vector of an equality-constrained least squares problem. The methods are matched to the solution algorithms given in the book, 'Solving Least Squares Problems.'
NASA Astrophysics Data System (ADS)
Al-Zanaidi, M. A.; Grossmann, C.; Noack, A.
2006-04-01
As a rule, parabolic problems with nonsmooth data show rapid changes of its solution or even possess solutions of reduced smoothness. While for smooth data various time integration methods, e.g. the trapezoidal rule or the Euler backwards scheme, work efficiently, but in case of jumps effects of high-frequency oscillations are observable over a long time horizon or steep changes are smeared out. Implicit Taylor methods (ITM), which are mostly applied in specific applications, like interval methods, but not commonly used for general cases, combine high accuracy with strong damping of unwanted oscillations. These properties make them a good choice in case of nonsmooth data. In the present paper ITM are investigated in detail for semi-discrete linear parabolic problems. In ITM at each time level a large-scale linear system has to be solved and preconditioned conjugate gradient methods (PCG) can efficiently be applied. Here adapted preconditioners are constructed, and tight spectral bounds are derived which are independent of the discretization parameters of the parabolic problem. As an important application ITM are considered in case of boundary heat control. Occurring control constraints are involved by means of penalty functions. To solve the completely discretized problem gradient-based numerical algorithms are used where the gradient of the objective is partially evaluated via discrete adjoints and partially by explicitly available terms corresponding to the penalties. Some test examples illustrate the efficiency of the considered algorithms.
NASA Astrophysics Data System (ADS)
Tatsii, R. M.; Pazen, O. Yu.
2016-03-01
A constructive scheme for the construction of a solution of a mixed problem for the heat conduction equation with piecewise-continuous coefficients coordinate-dependent in the final interval is suggested and validated in the present work. The boundary conditions are assumed to be most general. The scheme is based on: the reduction method, the concept of quasi-derivatives, the currently accepted theory of the systems of linear differential equations, the Fourier method, and the modified method of eigenfunctions. The method based on this scheme should be related to direct exact methods of solving mixed problems that do not employ the procedures of constructing Green's functions or integral transformations. Here the theorem of eigenfunction expansion is adapted for the case of coefficients that have discontinuity points of the 1st kind. The results obtained can be used, for example, in investigating the process of heat transfer in a multilayer slab under conditions of ideal thermal contact between the layers. A particular case of piecewise-continuous coefficients is considered. A numerical example of calculation of a temperature field in a real four-layer building slab under boundary conditions of the 3rd kind (conditions of convective heat transfer) that model the phenomenon of fire near one of the external surfaces is given.
NASA Technical Reports Server (NTRS)
Jhaveri, B. S.; Rosenberger, F.
1982-01-01
Definite triple integrals encountered in applying the Galerkin method to the problem of heat and mass transfer across rectangular enclosures are discussed. Rather than evaluating them numerically, the technique described by Reid and Harris (1958) was extended to obtain the exact solution of the integrals. In the process, four linear simultaneous equations with triple integrals as unknowns were obtained. These equations were then solved exactly to obtain the closed form solution. Since closed form representations of this type have been shown to be useful in solving nonlinear hydrodynamic problems by series expansion, the integrals are presented here in general form.
Characteristic of Absorption Heat Transfer using LiBr+LiI Solution
NASA Astrophysics Data System (ADS)
Tsujimori, Atsushi; Ozaki, Eiichi; Nakao, Kazushige
LiBr-H20 absorption chiller is widely used in Japan, and many research have been made for absorption characteristic in terms of enhancing heat transfer. Another study have been performed for widening working range with higher crystallization limits, and it was reported that adding LiI salt to LiBr-H20 working fluid provide about 5 [mass%] higher crystallization limit under the condition of absorption pressure range. It is necessary to reveal absorption heat transfer performance to utilize this working fluid pair for absorption chiller. In this study absorption heat transfer characteristic was investigated for horizontal and vertical tube. As a result, it was found that heat transfer coefficient increased as mass flow rate of solution increased and mass concentration of solution decrease and that these characteristic were almost the same as LiBr solution, though this solution gave slightly less heat transfer coefficient than LiBr solution.
Finite element method formulation in polar coordinates for transient heat conduction problems
NASA Astrophysics Data System (ADS)
Duda, Piotr
2016-04-01
The aim of this paper is the formulation of the finite element method in polar coordinates to solve transient heat conduction problems. It is hard to find in the literature a formulation of the finite element method (FEM) in polar or cylindrical coordinates for the solution of heat transfer problems. This document shows how to apply the most often used boundary conditions. The global equation system is solved by the Crank-Nicolson method. The proposed algorithm is verified in three numerical tests. In the first example, the obtained transient temperature distribution is compared with the temperature obtained from the presented analytical solution. In the second numerical example, the variable boundary condition is assumed. In the last numerical example the component with the shape different than cylindrical is used. All examples show that the introduction of the polar coordinate system gives better results than in the Cartesian coordinate system. The finite element method formulation in polar coordinates is valuable since it provides a higher accuracy of the calculations without compacting the mesh in cylindrical or similar to tubular components. The proposed method can be applied for circular elements such as boiler drums, outlet headers, flux tubes. This algorithm can be useful during the solution of inverse problems, which do not allow for high density grid. This method can calculate the temperature distribution in the bodies of different properties in the circumferential and the radial direction. The presented algorithm can be developed for other coordinate systems. The examples demonstrate a good accuracy and stability of the proposed method.
Solution to the galactic foreground problem for LISA
NASA Astrophysics Data System (ADS)
Crowder, Jeff; Cornish, Neil J.
2007-02-01
Low frequency gravitational wave detectors, such as the Laser Interferometer Space Antenna (LISA), will have to contend with large foregrounds produced by millions of compact galactic binaries in our galaxy. While these galactic signals are interesting in their own right, the unresolved component can obscure other sources. The science yield for the LISA mission can be improved if the brighter and more isolated foreground sources can be identified and regressed from the data. Since the signals overlap with one another, we are faced with a “cocktail party” problem of picking out individual conversations in a crowded room. Here we present and implement an end-to-end solution to the galactic foreground problem that is able to resolve tens of thousands of sources from across the LISA band. Our algorithm employs a variant of the Markov chain Monte Carlo (MCMC) method, which we call the blocked annealed Metropolis-Hastings (BAM) algorithm. Following a description of the algorithm and its implementation, we give several examples ranging from searches for a single source to searches for hundreds of overlapping sources. Our examples include data sets from the first round of mock LISA data challenges.
Large matrix solution techniques applied to an electromagnetic scattering problem
NASA Astrophysics Data System (ADS)
Woodworth, Margaret B.
1988-11-01
There are many numerical applications where one must solve a large system of linear equations. In order to do this, two issues must be addressed: Storage of the large matrices and finding an efficient technique to solve this large system of equations. This report looks at these issues as they apply to a given electromagnetic scattering problem. Surface integral equations are solved to find the surface currents and the far-field scattering from a three-dimensional conducting cube. This three-dimensional scattering problem is solved by Magnetic-Field Integral Equations (MFIE), Augmented Magnetic-Field Integral Equations (AMFIE), or, the recently developed, dual-surface magnetic-field integral equations. Various methods are reported for dealing with the shortage of memory - Unified Extended Memory (UEM), virtual memory, mass storage, and direct access fields. These methods can be used to increase the size of available matrix memory, without vastly increasing the CPU time beyond the time that would be required with central memory alone. Three techniques of matrix solution are discussed: Gaussian elimination, the conjugate gradient, and the biconjugate gradient methods. The computations reported here were done on three representative scientific computers: A Cyber 860 with NOS 2.5 operating system, a VAX 8650 and a Vax 11/780. Both Vaxes have Vax/VMS version 4.7 operating system.
NASA Astrophysics Data System (ADS)
Garashchenko, A. N.; Rudzinsky, V. P.; Garashchenko, N. A.
2016-02-01
Results of solving problems of simulating temperature fields in domains with movable boundaries of characteristic zones of intensive physical-chemical and thermomechanical transformations to be realized in materials upon high-temperature heating have been presented. Intumescent fire-protective coatings based on organic and mineral materials are the object of study. Features of numerical realization of input equation systems taking into account, in particular, a dynamics of considerable increase and subsequent decrease of the intumescent layer thickness have been considered. Example calculations for structures of metal and wood protected with various coatings are given. Results of calculating two-dimensional temperature fields in polymer composite square-shaped structures with internal cruciform load-bearing elements have been presented. The intumescent coating is arranged on the external surface of a structure. The solution of the above-listed problems is of important significance to provide fire protection of different-purpose structures and products.
A BARYONIC SOLUTION TO THE MISSING SATELLITES PROBLEM
Brooks, Alyson M.; Kuhlen, Michael; Zolotov, Adi; Hooper, Dan E-mail: mqk@astro.berkeley.edu E-mail: dhooper@fnal.gov
2013-03-01
It has been demonstrated that the inclusion of baryonic physics can alter the dark matter densities in the centers of low-mass galaxies, making the central dark matter slope more shallow than predicted in pure cold dark matter simulations. This flattening of the dark matter profile can occur in the most luminous subhalos around Milky Way mass galaxies. Zolotov et al. have suggested a correction to be applied to the central masses of dark matter-only satellites in order to mimic the affect of (1) the flattening of the dark matter cusp due to supernova feedback in luminous satellites and (2) enhanced tidal stripping due to the presence of a baryonic disk. In this paper, we apply this correction to the z = 0 subhalo masses from the high resolution, dark matter-only Via Lactea II (VL2) simulation, and find that the number of massive subhalos is dramatically reduced. After adopting a stellar mass to halo mass relationship for the VL2 halos, and identifying subhalos that are (1) likely to be destroyed by stripping and (2) likely to have star formation suppressed by photo-heating, we find that the number of massive, luminous satellites around a Milky Way mass galaxy is in agreement with the number of observed satellites around the Milky Way or M31. We conclude that baryonic processes have the potential to solve the missing satellites problem.
A Baryonic Solution to the Missing Satellites Problem
Brooks, Alyson M.; Kuhlen, Michael; Zolotov, Adi; Hooper, Dan
2013-03-01
It has been demonstrated that the inclusion of baryonic physics can alter the dark matter densities in the centers of low-mass galaxies, making the central dark matter slope more shallow than predicted in pure cold dark matter simulations. This flattening of the dark matter profile can occur in the most luminous subhalos around Milky Way mass galaxies. Zolotov et al. have suggested a correction to be applied to the central masses of dark matter-only satellites in order to mimic the affect of (1) the flattening of the dark matter cusp due to supernova feedback in luminous satellites and (2) enhanced tidal stripping due to the presence of a baryonic disk. In this paper, we apply this correction to the z = 0 subhalo masses from the high resolution, dark matter-only Via Lactea II (VL2) simulation, and find that the number of massive subhalos is dramatically reduced. After adopting a stellar mass to halo mass relationship for the VL2 halos, and identifying subhalos that are (1) likely to be destroyed by stripping and (2) likely to have star formation suppressed by photo-heating, we find that the number of massive, luminous satellites around a Milky Way mass galaxy is in agreement with the number of observed satellites around the Milky Way or M31. We conclude that baryonic processes have the potential to solve the missing satellites problem
Classical heat transport in anharmonic molecular junctions: exact solutions.
Liu, Sha; Agarwalla, Bijay Kumar; Wang, Jian-Sheng; Li, Baowen
2013-02-01
We study full counting statistics for classical heat transport through anharmonic or nonlinear molecular junctions formed by interacting oscillators. An analytical result of the steady-state heat flux for an overdamped anharmonic junction with arbitrary temperature bias is obtained. It is found that the thermal conductance can be expressed in terms of a temperature-dependent effective force constant. The role of anharmonicity is identified. We also give the general formula for the second cumulant of heat in steady state, as well as the average geometric heat flux when two system parameters are modulated adiabatically. We present an anharmonic example for which all cumulants for heat can be obtained exactly. For a bounded single oscillator model with mass we found that the cumulants are independent of the nonlinear potential.
Three embedded techniques for finite element heat flow problem with embedded discontinuities
NASA Astrophysics Data System (ADS)
Davari, M.; Rossi, R.; Dadvand, P.
2017-06-01
The present paper explores the solution of a heat conduction problem considering discontinuities embedded within the mesh and aligned at arbitrary angles with respect to the mesh edges. Three alternative approaches are proposed as solutions to the problem. The difference between these approaches compared to alternatives, such as the eXtended Finite Element Method (X-FEM), is that the current proposal attempts to preserve the global matrix graph in order to improve performance. The first two alternatives comprise an enrichment of the Finite Element (FE) space obtained through the addition of some new local degrees of freedom to allow capturing discontinuities within the element. The new degrees of freedom are statically condensed prior to assembly, so that the graph of the final system is not changed. The third approach is based on the use of modified FE-shape functions that substitute the standard ones on the cut elements. The imposition of both Neumann and Dirichlet boundary conditions is considered at the embedded interface. The results of all the proposed methods are then compared with a reference solution obtained using the standard FE on a mesh containing the actual discontinuity.
On the Solar wind Origin Problem and its Evolutionary Solution
NASA Astrophysics Data System (ADS)
Veselovsky, I.
2008-09-01
We demonstrate that the solar wind origin problem can have only one evolutionary solution. It is not known when and how the solar wind started to blow, but there are evidences that it existed on the geological time scale and will continue to exist even during crossing of dense galactic arms by the Sun in future. The Hayashi phase or the ignition of the thermonuclear burning could be an evolutionary benchmark in this respect, but details are not elaborated. It is also often assumed as plausible (but not proven) in available macroscopic and kinetic plasma theories that the solar wind exists because of the hot and dense corona with high pressure of gas and magnetic fields from one side near the Sun and rarefied low density, low temperature and low magnetic fields in the interstellar medium surrounding the Sun from the other side. Nevertheless, all these conditions are compatible both with inflow (accretion) and outflow (breeze and wind) branches of the same quasi steady politropic model solution of the Bernoulli equation without jumps considered by Bondi (1952) and Parker (1957). The solution of the quadratic equation is twice eroded and can only depict, but not predict the situation, which is totally prescribed by initial and boundary conditions at the star and in the interstellar medium around it. The definitive answers to the posed questions can be found only based on time dependent theories and observations. The magnetic, thermal and gravitational pumping of the material in the atmosphere of the star can proceed (and observed indeed) in both directions - away from the star and towards the star along finite (convective) or infinite (outflow/inflow) trajectories in kinetic or fluid approximations. Microphysical, macro-physical and global processes on the Sun and sun-like stars are non-locally and non-linearly coupled in a complicated way described by dimensionless scaling based on dissipative MHD and plasma kinetic equations with radiation. The question about
Metal cladding envelope problems, retrofit solutions, and quality control investigations
NASA Astrophysics Data System (ADS)
Colantonio, Antonio
1992-04-01
This paper deals with a case study of a building envelope retrofit of an insulated sheet steel and corrugated metal clad building. The building in discussion is a satellite testing facility which requires specific clean room conditions with controlled interior temperature (22 degree(s)C +/- 1 degree(s)C) and high relative humidity conditions (45% +/- 3%) to facilitate satellite testing programs. Preliminary mechanical system inspections indicated substantial increase in air intake to make up for air leakage losses. An infrared inspection along with an approximate air leakage test of the building envelope was requested by the client to determine the magnitude of the building envelope problem. This investigation concluded that significant air leakage was present throughout the building envelope and that existing mechanical systems did not have sufficient capacity to pressurize the building and negate wind and stack effect. Exfiltration particularly through openings on the top sections of the building were causing interior moisture to saturate wall insulation and render it ineffective. Concern for rusting of metal components was indicated. The subsequent envelope analysis discovered a number of typical metal building details that led to poor air tightness and wall insulation ineffectiveness. These were correlated to infrared investigation data. The retrofit solutions produced for this building not only apply to this building but to other similar building types. Further investigations indicated that air leakage and mechanical system performance were significant problems with buildings using metal cladding systems comparable to this building. Quality control before, during and after construction was identified as an important function of the architectural commissioning of the retrofit work and infrared investigations were used to verify locations of air leakage and insulation effectiveness.
Shadid, J.N.; Tuminaro, R.S.; Walker, H.F.
1997-02-01
The solution of the governing steady transport equations for momentum, heat and mass transfer in flowing fluids can be very difficult. These difficulties arise from the nonlinear, coupled, nonsymmetric nature of the system of algebraic equations that results from spatial discretization of the PDEs. In this manuscript the authors focus on evaluating a proposed nonlinear solution method based on an inexact Newton method with backtracking. In this context they use a particular spatial discretization based on a pressure stabilized Petrov-Galerkin finite element formulation of the low Mach number Navier-Stokes equations with heat and mass transport. The discussion considers computational efficiency, robustness and some implementation issues related to the proposed nonlinear solution scheme. Computational results are presented for several challenging CFD benchmark problems as well as two large scale 3D flow simulations.
New approaches for efficient solution of hitting set problem
NASA Technical Reports Server (NTRS)
Fijany, Amir; Vatan, Farrokh
2004-01-01
A new method for solving the hitting set problem is proposed. This method is based on the mapping of the problem onto an integer programming optimization problem. this new approach provides an algorithm with much better performance compare to the algorithms for the hitting set problem that currently are used for solving the diagnosis problem.
Technology Solutions Case Study: Heat Pump Water Heater Retrofit
none,
2012-08-01
In this project, Pacific Northwest National Laboratory studied heat pump water heaters, an efficient, cost-effective alternative to traditional electric resistance water heaters that can improve energy efficiency by up to 62%.
Work force problems in nuclear medicine and possible solutions.
Lull, R J; Littlefield, J L
1993-01-01
medicine) FTE work load. Work force shortage of nuclear medicine technologists remains a chronic problem in spite of extensive study: however, recent predictions suggest some improvement in the future. Solutions to work force problems facing nuclear medicine will require ongoing data surveys, aggressive recruitment of trainees, expansion of training positions, and socioeconomic initiatives that promote desirable future practice models.
[Decentralization: part of the health system problem or the solution?].
López-Casasnovas, G; Rico, A
2003-01-01
The greatest change experienced by the Spanish health system in the last two decades has probably been the devolution of power to the autonomous communities composing the Spanish state. This may generate tensions in the status quo and poses questions of whether decentralization of the health system is compatible with a cohesive national health system and whether this devolution of power is part of the problem of the health system or part of its solution. Generalized devolution occurring as rapidly as that produced in Spain (negotiated in slightly less than 6 months, with minimal financial agreements, without explicit legal frameworks in the areas of coordination and development of basic norms, and with a new agreement of general financing of the autonomous communities which possibly contains lacunae, etc.) presents an uncertain panorama. The possible misuse of the wide powers recently transferred to the autonomous communities could easily be used by those who would like to see a restoration of pre-democratic centralism to sow fear of the collapse of the health service as the cornerstone of the welfare state among the general public. The present article briefly addresses these questions.
Coding external causes of injuries: problems and solutions.
McKenzie, Kirsten; Enraght-Moony, Emma; Harding, Leith; Walker, Sue; Waller, Garry; Chen, Linping
2008-03-01
Complete and accurate information about hospitalised injuries is essential for injury risk and outcome research, though the accuracy and reliability of hospital data for injury surveillance are often questioned. To ascertain clinical coders' views of the reasons for a lack of specificity in external cause code usage and ways to improve external cause coding, a nationwide survey of coders was conducted in Australia in 2006. Four hundred and two coders participated in the questionnaire. The results of this study show that discharge summaries and doctors' notes were the poorest source of information regarding external causes, place of injury occurrence, and activity at the time of injury. Coders viewed missing external cause information and missing documentation as having the greatest impact on the quality of external cause coding. A large majority of coders suggested that improving clinical documentation in the emergency department and introducing a centralised structured form for external cause information would improve the quality of external cause coding. Clinical coders are a valuable source of information regarding problems with, and solutions to the collection of high quality data and this research has highlighted several areas where improvements can be made and further research is needed.
NASA Astrophysics Data System (ADS)
Ocłoń, Paweł; Łopata, Stanisław; Nowak, Marzena
2013-09-01
The finite element method (FEM) is one of the most frequently used numerical methods for finding the approximate discrete point solution of partial differential equations (PDE). In this method, linear or nonlinear systems of equations, comprised after numerical discretization, are solved to obtain the numerical solution of PDE. The conjugate gradient algorithms are efficient iterative solvers for the large sparse linear systems. In this paper the performance of different conjugate gradient algorithms: conjugate gradient algorithm (CG), biconjugate gradient algorithm (BICG), biconjugate gradient stabilized algorithm (BICGSTAB), conjugate gradient squared algorithm (CGS) and biconjugate gradient stabilized algorithm with l GMRES restarts (BICGSTAB(l)) is compared when solving the steady-state axisymmetric heat conduction problem. Different values of l parameter are studied. The engineering problem for which this comparison is made is the two-dimensional, axisymmetric heat conduction in a finned circular tube.
Numerical Solution of Ill Posed Problems in Partial Differential Equations
1988-06-30
periodic solutions of semilinear wave equations in exterior domains (breathers). Necessary and sufficient conditions for the existence of such solutions...numerically, that radial, global , positive solutions of the equation div grad u + uq u = 0 (X > 0, q > 1). ((1+1grad ul ) / exist for all X sufficiently... equation with a semilinear boundary condition , to appear in SIAM J. Math. Anal. 17] Levine, H.A. and Protter, M.H., The breakdown of solutions of
Inverse boundary value problem for anisotropic heat operators
NASA Astrophysics Data System (ADS)
Kim, Kyoungsun; Nakamura, Gen
2011-04-01
As a mathematical model of thermography, a reconstruction scheme called the dynamical probe method is given for identifying unknown separated inclusions inside a known anisotropic heat conductor. The heat conductivities of inclusions can be also anisotropic. The measured data is the so called Neumann to Dirichlet map which is a mathematical idealization of many measurements consisting of injecting heat flux and measuring the corresponding heat distribution on the part of the boundary of the known heat conductor by infrared camera for any fixed time interval. This idealization becomes relevant if we have for instance the cooling boundary condition on the other part of the boundary. This is due to the exponential decay of temperature in time which enables to conduct many measurements in a short time.
Kurtosis Approach to Solution of a Nonlinear ICA Problem
NASA Technical Reports Server (NTRS)
Duong, Vu; Stubberud, Allen
2009-01-01
An algorithm for solving a particular nonlinear independent-component-analysis (ICA) problem, that differs from prior algorithms for solving the same problem, has been devised. The problem in question of a type known in the art as a post nonlinear mixing problem is a useful approximation of the problem posed by the mixing and subsequent nonlinear distortion of sensory signals that occur in diverse scientific and engineering instrumentation systems.
NASA Astrophysics Data System (ADS)
Kogoj, Alessia E.
2017-02-01
We show how to apply harmonic spaces potential theory in the study of the Dirichlet problem for a general class of evolution hypoelliptic partial differential equations of second order. We construct Perron-Wiener solution and we provide a sufficient condition for the regularity of the boundary points. Our criterion extends and generalizes the classical parabolic-cone criterion for the Heat equation due to Effros and Kazdan.
NASA Astrophysics Data System (ADS)
Hong, Hakho; Wang, Teng
2017-08-01
In this paper, we investigate the one-dimensional motion of compressible viscous and heat-conductive fluid on the half line \\renewcommand{\\b}β \\renewcommand{\\i}∞ {\\boldsymbol R}_+=(0, +∞) . The large-time behavior of the superposition of the transonic (or degenerate) boundary layer solution, 1-rarefaction wave, 2-viscous contact wave and 3-rarefaction wave is established for the inflow problem of full compressible Navier-Stokes system under a large initial perturbation for any adiabatic exponent \
Solution of the inverse problem of magnetic induction tomography (MIT).
Merwa, Robert; Hollaus, Karl; Brunner, Patricia; Scharfetter, Hermann
2005-04-01
Magnetic induction tomography (MIT) of biological tissue is used to reconstruct the changes in the complex conductivity distribution inside an object under investigation. The measurement principle is based on determining the perturbation DeltaB of a primary alternating magnetic field B0, which is coupled from an array of excitation coils to the object under investigation. The corresponding voltages DeltaV and V0 induced in a receiver coil carry the information about the passive electrical properties (i.e. conductivity, permittivity and permeability). The reconstruction of the conductivity distribution requires the solution of a 3D inverse eddy current problem. As in EIT the inverse problem is ill-posed and on this account some regularization scheme has to be applied. We developed an inverse solver based on the Gauss-Newton-one-step method for differential imaging, and we implemented and tested four different regularization schemes: the first and second approaches employ a classical smoothness criterion using the unit matrix and a differential matrix of first order as the regularization matrix. The third method is based on variance uniformization, and the fourth method is based on the truncated singular value decomposition. Reconstructions were carried out with synthetic measurement data generated with a spherical perturbation at different locations within a conducting cylinder. Data were generated on a different mesh and 1% random noise was added. The model contained 16 excitation coils and 32 receiver coils which could be combined pairwise to give 16 planar gradiometers. With 32 receiver coils all regularization methods yield fairly good 3D-images of the modelled changes of the conductivity distribution, and prove the feasibility of difference imaging with MIT. The reconstructed perturbations appear at the right location, and their size is in the expected range. With 16 planar gradiometers an additional spurious feature appears mirrored with respect to the median
Heats of immersion of titania powders in primer solutions
NASA Technical Reports Server (NTRS)
Siriwardane, R.; Wightman, J. P.
1983-01-01
The oxide layer present on titanium alloys can play an important role in determining the strength and durability of adhesive bonds. Here, three titania powders in different crystalline phases, rutile-R1, anatase-A1, and anatase-A2, are characterized by several techniques. These include microelectrophoresis, X-ray diffractometry, surface area pore volume analysis, X-ray photoelectron spectroscopy, and measurements of the heats of immersion. Of the three powders, R1 has the highest heat of immersion in water, while the interaction between water and A1 powder is low. Experimental data also suggest a specific preferential interaction of polyphenylquinoxaline with anatase.
Lunar Dust on Heat Rejection System Surfaces: Problems and Prospects
NASA Technical Reports Server (NTRS)
Gaier, James R.; Jaworske, Donald A.
2007-01-01
Heat rejection from power systems will be necessary for human and robotic activity on the lunar surface. Functional operation of such heat rejection systems is at risk of degradation as a consequence of dust accumulation. The Apollo astronauts encountered marked degradation of performance in heat rejection systems for the lunar roving vehicle, science packages, and other components. Although ground testing of dust mitigation concepts in support of the Apollo mission identified mitigation tools, the brush concept adopted by the Apollo astronauts proved essentially ineffective. A better understanding of the issues associated with the impact of lunar dust on the functional performance of heat rejection systems and its removal is needed as planning gets underway for human and robotic missions to the Moon. Renewed emphasis must also be placed on ground testing of pristine and dust-covered heat rejection system surfaces to quantify degradation and address mitigation concepts. This paper presents a review of the degradation in performance of heat rejection systems encountered on the lunar surface to-date, and will discuss current activities underway to evaluate the durability of candidate heat rejection system surfaces and current dust mitigation concepts.
Lunar Dust on Heat Rejection System Surfaces: Problems and Prospects
NASA Astrophysics Data System (ADS)
Gaier, James R.; Jaworske, Donald A.
2007-01-01
Heat rejection from power systems will be necessary for human and robotic activity on the lunar surface. Functional operation of such heat rejection systems is at risk of degradation as a consequence of dust accumulation. The Apollo astronauts encountered marked degradation of performance in heat rejection systems for the lunar roving vehicle, science packages, and other components. Although ground testing of dust mitigation concepts in support of the Apollo mission identified candidate mitigation tools, the brush concept adopted by the Apollo astronauts proved essentially ineffective. A better understanding of the issues associated with the impact of lunar dust on the functional performance of heat rejection systems and its removal is needed as planning gets underway for human and robotic missions to the Moon. Renewed emphasis must also be placed on ground testing of pristine and dust-covered heat rejection system surfaces to quantify degradation and address mitigation concepts. This paper presents a review of the degradation of heat rejection systems encountered on the lunar surface to-date, and discusses current activities underway to evaluate the durability of candidate heat rejection system surfaces and current dust mitigation concepts.
The nature of the sunspot phenomenon. I - Solutions of the heat transport equation
NASA Technical Reports Server (NTRS)
Parker, E. N.
1974-01-01
It is pointed out that sunspots represent a disruption in the uniform flow of heat through the convective zone. The basic sunspot structure is, therefore, determined by the energy transport equation. The solutions of this equation for the case of stochastic heat transport are examined. It is concluded that a sunspot is basically a region of enhanced, rather than inhibited, energy transport and emissivity. The heat flow equations are discussed and attention is given to the shallow depth of the sunspot phenomenon. The sunspot is seen as a heat engine of high efficiency which converts most of the heat flux into hydromagnetic waves.
River Restoration Within Water Supply Areas - Problems and Solution Approaches
NASA Astrophysics Data System (ADS)
Regli, C.; Huggenberger, P.; Guldenfels, L.
2004-05-01
The demand of river restoration in many areas of Europe and North America clarifies the existing problems of a sustainable use of water resources. River restoration generally intensifies the exchange between surface- and groundwater and related dissolved compounds or particles. Recommendations concerning ecological measures of river restoration within water supply areas should allow differentiated solutions, which take into account groundwater and flood protection. Model scenarios play an important role in decision-making processes. An application of this approach is given for the groundwater production system of the city of Basel, Switzerland: The former channelized river Wiese should be restored to more natural conditions to re-establish the biological connectivity and to increase the recreational value of this area. These initiatives might conflict with the requirements of groundwater protection, especially during flood events. Therefore, processes of river-groundwater interaction have been characterized by analyses of physical, chemical, and microbiological data sampled in several well clusters between the river and production wells. The well clusters allow sampling of groundwater in different depths of the aquifer. These data together with data from tracer experiments are used for modeling the river-groundwater interaction. The large- and medium-scaled, transient groundwater models are used to evaluate the well capture zones in the different river restoration scenarios. Well capture zones have to satisfy the safety requirements of groundwater protection. A further step includes optimizations of water supply operation such as artificial recharge and pumping. At the small scale, uncertainty estimations concerning delineation of well capture zones are made by stochastic approaches including geological and geophysical data of the aquifer. The methods presented can be used to define and evaluate groundwater protection zones in heterogeneous aquifers associated with
Enhancement of Pool Boiling Heat Transfer to Lithium Bromide Aqueous Solution
NASA Astrophysics Data System (ADS)
Furukawa, Masahiro; Kaji, Masuo; Suyama, Takayuki; Sekoguchi, Kotohiko
An experimental study on enhancement of nucleate pool boiling heat tranfer by placing a sponge metal close to a plain heated surface was conducted in order to improve the heat transfer performance of the high temperature generator of absorption chiller/heater. The sponge metal has three dimensional porous mesh framework like sponge. Boiling curves of water under the atmospheric pressure were compared with those of lithium bromide aqueous solution of mass concentration 55 to 58%. Heat transfer characteristics were improved by 2 to3 times both for water and lithium bromide aqueous solution when the sponge metal was placed on the heated surface with and without cleareance. Three kinds of sponge metals were used for lithium bromide aqueous solution under the reduced pressure (24 kPa). At lower heat fluxes,#6 sponge metal which has the finest mesh and the lowest porosity shows excellent results. At high heat fluxes, however,it causes deterioration of heat transfer. Over the wide range of heat fluxes,# 4 sponge metal was found to be most suitable and the optimal clearence was determined as 0.5 mm. The sponge metal is of good practical use as a device to enhance the boiling, since no special manufacturing is required for placing it on the heated surface.
Enhancement of pool boiling heat transfer to lithium bromide aqueous solution
NASA Astrophysics Data System (ADS)
Kaji, Masuo; Furukawa, Masahiro; Suyama, Takayuki; Sekoguchi, Kotohiko
1995-04-01
An experimental study on enhancement of nucleate pool boiling heat transfer by placing a sponge metal, which had a three-dimensional mesh structure like sponge, close to a plain smooth heat transfer surface was conducted to improve the heat transfer performance of the high temperature generator of absorption chiller/heaters. Boiling curves of water and lithium bromide aqueous solution of mass concentration of 55 to 58% at the atmospheric pressure were presented. Heat transfer characteristics were improved by two to three times both for water and lithium bromide aqueous solution when the sponge metal was attached with an appropriate clearance. Three kinds of sponge metals were tested for lithium bromide aqueous solution under a reduced pressure (24 kPa). The sponge metal #6, which had the finest mesh among the three sponge metals, brought about excellent results at lower heat fluxes, but it caused deterioration of heat transfer at higher heat fluxes. For the wide range of heat flux (5 x 10(exp 4) approximately 2 x 10(exp 5) W/m(exp 2), it was found that the sponge metal #4 with the middle fineness was the most suitable and the optimal clearance was in the range of 0.1 approximately 0.5 mm. The employment of sponge metals for enhancing boiling heat transfer is practically excellent, since no special manufacturing is required to mount them on the heated surface.
A Heat Vulnerability Index and Adaptation Solutions for Pittsburgh, Pennsylvania.
Bradford, Kathryn; Abrahams, Leslie; Hegglin, Miriam; Klima, Kelly
2015-10-06
With increasing evidence of global warming, many cities have focused attention on response plans to address their populations' vulnerabilities. Despite expected increased frequency and intensity of heat waves, the health impacts of such events in urban areas can be minimized with careful policy and economic investments. We focus on Pittsburgh, Pennsylvania and ask two questions. First, what are the top factors contributing to heat vulnerability and how do these characteristics manifest geospatially throughout Pittsburgh? Second, assuming the City wishes to deploy additional cooling centers, what placement will optimally address the vulnerability of the at risk populations? We use national census data, ArcGIS geospatial modeling, and statistical analysis to determine a range of heat vulnerability indices and optimal cooling center placement. We find that while different studies use different data and statistical calculations, all methods tested locate additional cooling centers at the confluence of the three rivers (Downtown), the northeast side of Pittsburgh (Shadyside/Highland Park), and the southeast side of Pittsburgh (Squirrel Hill). This suggests that for Pittsburgh, a researcher could apply the same factor analysis procedure to compare data sets for different locations and times; factor analyses for heat vulnerability are more robust than previously thought.
Genetic solutions to infertility caused by heat stress
USDA-ARS?s Scientific Manuscript database
Reproductive function in mammals is very susceptible to disruption by heat stress. In lactating dairy cows, for example, pregnancy rates per insemination can be as low as 10-15% in the summer vs. 25-40% in cool weather. Reduced fertility in females is caused by a combination of 1) the negative cons...
A Heat Vulnerability Index and Adaptation Solutions for Pittsburgh, Pennsylvania
NASA Astrophysics Data System (ADS)
Klima, K.; Abrahams, L.; Bradford, K.; Hegglin, M.
2015-12-01
With increasing evidence of global warming, many cities have focused attention on response plans to address their populations' vulnerabilities. Despite expected increased frequency and intensity of heat waves, the health impacts of such events in urban areas can be minimized with careful policy and economic investments. We focus on Pittsburgh, Pennsylvania and ask two questions. First, what are the top factors contributing to heat vulnerability and how do these characteristics manifest geospatially throughout Pittsburgh? Second, assuming the City wishes to deploy additional cooling centers, what placement will optimally address the vulnerability of the at risk populations? We use national census data, ArcGIS geospatial modeling, and statistical analysis to determine a range of heat vulnerability indices and optimal cooling center placement. We find that while different studies use different data and statistical calculations, all methods tested locate additional cooling centers at the confluence of the three rivers (Downtown), the northeast side of Pittsburgh (Shadyside/ Highland Park), and the southeast side of Pittsburgh (Squirrel Hill). This suggests that for Pittsburgh, a researcher could apply the same factor analysis procedure to compare datasets for different locations and times; factor analyses for heat vulnerability are more robust than previously thought.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-06-16
... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration Trueheat, Inc., a Subsidiary of Global Heating Solutions, Inc., Currently Known as Truheat, a Division of Three Heat LLC, Allegan, MI; Electro-Heat, Inc., a Subsidiary of Global Heating Solutions, Inc., Currently Known...
ERIC Educational Resources Information Center
Chronicle, Edward P.; MacGregor, James N.; Ormerod, Thomas C.
2004-01-01
Four experiments investigated transformation problems with insight characteristics. In Experiment 1, performance on a version of the 6-coin problem that had a concrete and visualizable solution followed a hill-climbing heuristic. Experiment 2 demonstrated that the difficulty of a version of the problem that potentially required insight for…
Fundamental solution of the problem of linear programming and method of its determination
NASA Technical Reports Server (NTRS)
Petrunin, S. V.
1978-01-01
The idea of a fundamental solution to a problem in linear programming is introduced. A method of determining the fundamental solution and of applying this method to the solution of a problem in linear programming is proposed. Numerical examples are cited.
Impact of heat treatment on miscibility of proteins and disaccharides in frozen solutions.
Izutsu, Ken-ichi; Yomota, Chikako; Okuda, Haruhiro; Kawanishi, Toru; Randolph, Theodore W; Carpenter, John F
2013-10-01
The purpose of this study was to elucidate the effect of heat treatment (annealing) on the miscibility of concentrated protein and disaccharide mixtures in the freezing segment of lyophilization. Frozen solutions containing a protein (e.g., recombinant human albumin, chicken egg lysozyme, bovine plasma immunoglobulin G, or a humanized IgG1k monoclonal antibody) and a non-reducing disaccharide (e.g., sucrose or trehalose) showed single thermal transitions of the solute mixtures (glass transition temperature of maximally freeze-concentrated solutes: T(g)(')) in their first heating scans. Heat treatment (e.g., -5 °C, 30 min) of some disaccharide-rich mixture frozen solutions at temperatures far above their T(g)(') induced two-step T(g)(') transitions in the subsequent scans, suggesting the separation of the solutes into concentrated protein-disaccharide mixture phase and disaccharide phase. Other frozen solutions showed a single transition of the concentrated solute mixture both before and after heat treatment. The apparent effects of the heat treatment temperature and time on the changes in thermal properties suggest molecular reordering of the concentrated solutes from a kinetically fixed mixture state to a more thermodynamically favorable state as a result of increased mobility. The implications of these phenomena on the quality of protein formulations are discussed. Copyright © 2013 Elsevier B.V. All rights reserved.
The solution of large multi-dimensional Poisson problems
NASA Technical Reports Server (NTRS)
Stone, H. S.
1974-01-01
The Buneman algorithm for solving Poisson problems can be adapted to solve large Poisson problems on computers with a rotating drum memory so that the computation is done with very little time lost due to rotational latency of the drum.
On Problems with Solutions Attainable in More Than One Way.
ERIC Educational Resources Information Center
Pedersen, Jean; Polya, George
1984-01-01
Presents three sample problems related to arithmetic and algebra, geometry, and calculus, indicating, in each case, similar problems that could be posed. Includes a discussion of positive benefits which result by asking students "Can you derive the result differently?" (JN)
Solvation thermodynamics and heat capacity of polar and charged solutes in water
Sedlmeier, Felix; Netz, Roland R.
2013-03-21
The solvation thermodynamics and in particular the solvation heat capacity of polar and charged solutes in water is studied using atomistic molecular dynamics simulations. As ionic solutes we consider a F{sup -} and a Na{sup +} ion, as an example for a polar molecule with vanishing net charge we take a SPC/E water molecule. The partial charges of all three solutes are varied in a wide range by a scaling factor. Using a recently introduced method for the accurate determination of the solvation free energy of polar solutes, we determine the free energy, entropy, enthalpy, and heat capacity of the three different solutes as a function of temperature and partial solute charge. We find that the sum of the solvation heat capacities of the Na{sup +} and F{sup -} ions is negative, in agreement with experimental observations, but our results uncover a pronounced difference in the heat capacity between positively and negatively charged groups. While the solvation heat capacity {Delta}C{sub p} stays positive and even increases slightly upon charging the Na{sup +} ion, it decreases upon charging the F{sup -} ion and becomes negative beyond an ion charge of q=-0.3e. On the other hand, the heat capacity of the overall charge-neutral polar solute derived from a SPC/E water molecule is positive for all charge scaling factors considered by us. This means that the heat capacity of a wide class of polar solutes with vanishing net charge is positive. The common ascription of negative heat capacities to polar chemical groups might arise from the neglect of non-additive interaction effects between polar and apolar groups. The reason behind this non-additivity is suggested to be related to the second solvation shell that significantly affects the solvation thermodynamics and due to its large spatial extent induces quite long-ranged interactions between solvated molecular parts and groups.
Solvation thermodynamics and heat capacity of polar and charged solutes in water.
Sedlmeier, Felix; Netz, Roland R
2013-03-21
The solvation thermodynamics and in particular the solvation heat capacity of polar and charged solutes in water is studied using atomistic molecular dynamics simulations. As ionic solutes we consider a F(-) and a Na(+) ion, as an example for a polar molecule with vanishing net charge we take a SPC/E water molecule. The partial charges of all three solutes are varied in a wide range by a scaling factor. Using a recently introduced method for the accurate determination of the solvation free energy of polar solutes, we determine the free energy, entropy, enthalpy, and heat capacity of the three different solutes as a function of temperature and partial solute charge. We find that the sum of the solvation heat capacities of the Na(+) and F(-) ions is negative, in agreement with experimental observations, but our results uncover a pronounced difference in the heat capacity between positively and negatively charged groups. While the solvation heat capacity ΔC(p) stays positive and even increases slightly upon charging the Na(+) ion, it decreases upon charging the F(-) ion and becomes negative beyond an ion charge of q = -0.3e. On the other hand, the heat capacity of the overall charge-neutral polar solute derived from a SPC/E water molecule is positive for all charge scaling factors considered by us. This means that the heat capacity of a wide class of polar solutes with vanishing net charge is positive. The common ascription of negative heat capacities to polar chemical groups might arise from the neglect of non-additive interaction effects between polar and apolar groups. The reason behind this non-additivity is suggested to be related to the second solvation shell that significantly affects the solvation thermodynamics and due to its large spatial extent induces quite long-ranged interactions between solvated molecular parts and groups.
Hardware problems encountered in solar heating and cooling systems
NASA Technical Reports Server (NTRS)
Cash, M.
1978-01-01
Numerous problems in the design, production, installation, and operation of solar energy systems are discussed. Described are hardware problems, which range from simple to obscure and complex, and their resolution.
A computational approach to calculate the heat of transport of aqueous solutions
NASA Astrophysics Data System (ADS)
di Lecce, Silvia; Albrecht, Tim; Bresme, Fernando
2017-03-01
Thermal gradients induce concentration gradients in alkali halide solutions, and the salt migrates towards hot or cold regions depending on the average temperature of the solution. This effect has been interpreted using the heat of transport, which provides a route to rationalize thermophoretic phenomena. Early theories provide estimates of the heat of transport at infinite dilution. These values are used to interpret thermodiffusion (Soret) and thermoelectric (Seebeck) effects. However, accessing heats of transport of individual ions at finite concentration remains an outstanding question both theoretically and experimentally. Here we discuss a computational approach to calculate heats of transport of aqueous solutions at finite concentrations, and apply our method to study lithium chloride solutions at concentrations >0.5 M. The heats of transport are significantly different for Li+ and Cl‑ ions, unlike what is expected at infinite dilution. We find theoretical evidence for the existence of minima in the Soret coefficient of LiCl, where the magnitude of the heat of transport is maximized. The Seebeck coefficient obtained from the ionic heats of transport varies significantly with temperature and concentration. We identify thermodynamic conditions leading to a maximization of the thermoelectric response of aqueous solutions.
A computational approach to calculate the heat of transport of aqueous solutions
Di Lecce, Silvia; Albrecht, Tim; Bresme, Fernando
2017-01-01
Thermal gradients induce concentration gradients in alkali halide solutions, and the salt migrates towards hot or cold regions depending on the average temperature of the solution. This effect has been interpreted using the heat of transport, which provides a route to rationalize thermophoretic phenomena. Early theories provide estimates of the heat of transport at infinite dilution. These values are used to interpret thermodiffusion (Soret) and thermoelectric (Seebeck) effects. However, accessing heats of transport of individual ions at finite concentration remains an outstanding question both theoretically and experimentally. Here we discuss a computational approach to calculate heats of transport of aqueous solutions at finite concentrations, and apply our method to study lithium chloride solutions at concentrations >0.5 M. The heats of transport are significantly different for Li+ and Cl− ions, unlike what is expected at infinite dilution. We find theoretical evidence for the existence of minima in the Soret coefficient of LiCl, where the magnitude of the heat of transport is maximized. The Seebeck coefficient obtained from the ionic heats of transport varies significantly with temperature and concentration. We identify thermodynamic conditions leading to a maximization of the thermoelectric response of aqueous solutions. PMID:28322266
Using Diagrams as Tools for the Solution of Non-Routine Mathematical Problems
ERIC Educational Resources Information Center
Pantziara, Marilena; Gagatsis, Athanasios; Elia, Iliada
2009-01-01
The Mathematics education community has long recognized the importance of diagrams in the solution of mathematical problems. Particularly, it is stated that diagrams facilitate the solution of mathematical problems because they represent problems' structure and information (Novick & Hurley, 2001; Diezmann, 2005). Novick and Hurley were the first…
Using Diagrams as Tools for the Solution of Non-Routine Mathematical Problems
ERIC Educational Resources Information Center
Pantziara, Marilena; Gagatsis, Athanasios; Elia, Iliada
2009-01-01
The Mathematics education community has long recognized the importance of diagrams in the solution of mathematical problems. Particularly, it is stated that diagrams facilitate the solution of mathematical problems because they represent problems' structure and information (Novick & Hurley, 2001; Diezmann, 2005). Novick and Hurley were the first…
Twin solution calorimeter determines heats of formation of alloys at high temperatures
NASA Technical Reports Server (NTRS)
Darby, J. B., Jr.; Kleb, R.; Kleppa, O. J.
1968-01-01
Calvert-type, twin liquid metal solution calorimeter determines the heats of formation of transition metal alloys at high temperatures. The twin differential calorimeter measures the small heat effects generated over extended periods of time, has maximum operating temperature of 1073 degrees K and an automatic data recording system.
NASA Astrophysics Data System (ADS)
Dimova, Stefka; Mihaylova, Yonita
2016-02-01
The numerical solution of nonlinear degenerate reaction-diffusion problems often meets two kinds of difculties: singularities in space - finite speed of propagation of compact supports' initial perturbations and possible sharp moving fronts, where the solution has low regularity, and singularities in time - blow-up or quenching in finite time. We propose and implement a combination of the sixth-order WENO scheme of Liu, Shu and Zhang [SIAM J.Sci.Comput. 33, 939-965 (2011)] with an adaptive procedure to deal with these singularities. Numerical results on the mathematical model of heat structures are shown.
Heat and mass transfer at adiabatic evaporation of binary zeotropic solutions
NASA Astrophysics Data System (ADS)
Makarov, M. S.; Makarova, S. N.
2016-01-01
Results of numerical simulation of heat and mass transfer in a laminar flow of three-component gas at adiabatic evaporation of binary solutions from a flat plate are presented. The studies were carried out for the perfect solution of ethanol/methanol and zeotrope solutions of water/acetone, benzene/acetone, and ethanol/acetone. The liquid-vapor equilibrium is described by the Raoult law for the ideal solution and Carlson-Colburn model for real solutions. The effect of gas temperature and liquid composition on the heat and diffusion flows, and temperature of vapor-gas mixture at the interface is analyzed. The formula for calculating the temperature of the evaporation surface for the binary liquid mixtures using the similarity of heat and mass transfer was proposed. Data of numerical simulations are in a good agreement with the results of calculations based on the proposed dependence for all examined liquid mixtures in the considered range of temperatures and pressures.
NASA Astrophysics Data System (ADS)
Hu, Zhang-Mao; Tian, Hong; Li, Ben-Wen; Zhang, Wei; Yin, Yan-Shan; Ruan, Min; Chen, Dong-Lin
2017-10-01
The ray-effect is a major discretization error in the approximate solution method for the radiative transfer equation (RTE). To overcome this problem, the incident energy transfer equation (IETE) is proposed. The incident energy, instead of radiation intensity, is obtained by directly solving this new equation. Good numerical properties are found for the incident energy transfer equation. To show the properties of numerical solution, the collocation spectral method (CSM) is employed to solve the incident energy transfer equation. Three test cases are taken into account to verify the performance of the incident energy transfer equation. The result shows that the radiative heat flux obtained based on IETE is much more accurate than that based on RTE, which means that the IETE is very effective in eliminating the impacts of ray-effect on the heat flux. However, on the contrary, the radiative intensity obtained based on IETE is less accurate than that based on RTE due to the ray-effect. So, this equation is more suitable for those radiative heat transfer problems, in which the radiation heat flux and incident energy are needed rather than the radiation intensity.
NASA Astrophysics Data System (ADS)
Amosov, A. A.
2016-07-01
A nonstationary initial boundary value problem describing the radiative-conductive heat exchange in a system of semitransparent bodies is considered. The radiation transfer equation with boundary conditions of mirror reflection and refraction according to the Fresnel laws is used to describe the propagation of radiation. The dependence of the radiation intensity and the optical properties of bodies on the radiation frequency is taken into account. The existence and uniqueness of a weak solution are proved. A comparison theorem is proved. Some a priori estimates for the weak solution are derived and its regularity is proved.
Steady Detonation Wave Solutions Under the Reaction Heat Effect
NASA Astrophysics Data System (ADS)
Carvalho, Filipe; Soares, Ana Jacinta
2010-04-01
The dynamics of the steady detonation wave is studied in the frame of the kinetic theory for a binary reacting mixture undergoing a chemical reaction of type A + A ⇌ B + B. The influence of the reaction heat on the detonation wave structure is investigated for the first time. Some numerical results are provided for a generic symmetric chemical reaction of exothermic and endothermic type.
Singular solutions of contact problems and block elements
NASA Astrophysics Data System (ADS)
Babeshko, V. A.; Evdokimova, O. V.; Babeshko, O. M.
2017-07-01
In this work, we consider mixed problems of elasticity theory, in particular, contact problems for cases that are nontraditional. They include mixed problems with discontinuous boundary conditions in which the singularities in the behavior of contact stresses are not studied or the energy of the singularities is unbounded. An example of such mixed problems is contact problems for two rigid stamps approaching each other by rectilinear boundaries up to contact but not merging into one stamp. It has been shown that such problems, which appear in seismology, failure theory, and civil engineering, have singular components with unbounded energy and can be solved by topological methods with pointwise convergence, in particular, by the block element method. Numerical methods that are based on using the energy integral are not applicable to such problems in view of its divergence.
Parents' Aggressive Influences and Children's Aggressive Problem Solutions with Peers
ERIC Educational Resources Information Center
Duman, Sarah; Margolin, Gayla
2007-01-01
This study examined children's aggressive and assertive solutions to hypothetical peer scenarios in relation to parents' responses to similar hypothetical social scenarios and parents' actual marital aggression. The study included 118 children ages 9 to 10 years old and their mothers and fathers. Children's aggressive solutions correlated with…
Finding Similarities and Differences in the Solutions of Word Problems
ERIC Educational Resources Information Center
Reed, Stephen K.; Stebick, Sara; Comey, Brittany; Carroll, Donja
2012-01-01
This study extends the Rittle-Johnson and Star (2009) research agenda of identifying when solution comparisons are effective by combining their quantitative approach with the qualitative descriptive approach advocated by Lobato (2008). In Experiment 1 university students described similarities and differences between detailed solutions of…
Finding Similarities and Differences in the Solutions of Word Problems
ERIC Educational Resources Information Center
Reed, Stephen K.; Stebick, Sara; Comey, Brittany; Carroll, Donja
2012-01-01
This study extends the Rittle-Johnson and Star (2009) research agenda of identifying when solution comparisons are effective by combining their quantitative approach with the qualitative descriptive approach advocated by Lobato (2008). In Experiment 1 university students described similarities and differences between detailed solutions of…
Parents' Aggressive Influences and Children's Aggressive Problem Solutions with Peers
ERIC Educational Resources Information Center
Duman, Sarah; Margolin, Gayla
2007-01-01
This study examined children's aggressive and assertive solutions to hypothetical peer scenarios in relation to parents' responses to similar hypothetical social scenarios and parents' actual marital aggression. The study included 118 children ages 9 to 10 years old and their mothers and fathers. Children's aggressive solutions correlated with…
Multichannel Coherent Lightwave Systems: Practical Problems and Possible Solutions
NASA Astrophysics Data System (ADS)
Tanrikulu, Mustafa Okan
1995-01-01
An extensive field deployment of optical fiber has already undergone, and it is expected to replace the copper within the next twenty years. The ultimate goal in communications and computing industry is to make all optical networks possible in the near future. In this context, certain important practical problems that exist in multichannel coherent lightwave systems are studied, and possible solutions are provided in this dissertation. It is shown that the capacity of dual-filter FSK heterodyne lightwave systems can be enhanced by exploiting the interrelationship between the frequency separation and the amount of laser phase noise. Optimum choice of intermediate frequency filter bandwidth also improves the system capacity. The effect of finite intermediate frequency on the performance of ASK heterodyne lightwave systems is also studied. The results obtained show that certain finite choices of intermediate frequency allows ideal envelope detection. Thus, one can design a multichannel ASK heterodyne lightwave system with relatively small optical domain channel spacings as long as optimum values of intermediate frequency is used. Otherwise, either the channel spacings should be increased, which, in turn, reduces the system capacity, or an extra sensitivity penalty should be tolerated which translates into an increase in the system cost. It is also shown that the effect of finite intermediate frequency is more significant in negligible linewidth systems. On the other hand, non-negligible linewidth systems are more immune to the effects of finite intermediate frequency. However, the amount of channel spacing in a multichannel system significantly increases in the case of non-negligible linewidth systems due to spectral broadening of information bearing signal. The effect of crosstalk in multi-channel ASK heterodyne lightwave systems with polarization control is also studied, and the results obtained show that choice of intermediate frequency filter bandwidth, in
Baumeister, P
2000-05-01
Two problems were proposed at the 1998 Conference on Optical Interference Coatings: dual-band antireflection coatings and bandpass filters. In excess of 40 solutions were submitted. An evaluation of those solutions is presented.
NASA Astrophysics Data System (ADS)
Nath, G.; Vishwakarma, J. P.
2014-05-01
The propagation of a spherical (or cylindrical) shock wave in a non-ideal gas with heat conduction and radiation heat-flux, in the presence of a spacially decreasing azimuthal magnetic field, driven out by a moving piston is investigated. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature and density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. The shock wave moves with variable velocity and the total energy of the wave is non-constant. Similarity solutions are obtained for the flow-field behind the shock and the effects of variation of the heat transfer parameters, the parameter of the non-idealness of the gas, both, decreases the compressibility of the gas and hence there is a decrease in the shock strength. Further, it is investigated that with an increase in the parameters of radiative and conductive heat transfer the tendency of formation of maxima in the distributions of heat flux, density and isothermal speed of sound decreases. The pressure and density vanish at the inner surface (piston) and hence a vacuum is form at the center of symmetry. The shock waves in conducting non-ideal gas with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, nuclear explosion, chemical detonation, rupture of a pressurized vessels, in the analysis of data from exploding wire experiments, and cylindrically symmetric hypersonic flow problems associated with meteors or reentry vehicles, etc. The findings of the present works provided a clear picture of whether and how the non-idealness parameter, conductive and radiative heat transfer parameters and the magnetic field affect the flow behind the shock
On optimal solutions of the constrained ℓ 0 regularization and its penalty problem
NASA Astrophysics Data System (ADS)
Zhang, Na; Li, Qia
2017-02-01
The constrained {{\\ell}0} regularization plays an important role in sparse reconstruction. A widely used approach for solving this problem is the penalty method, of which the least square penalty problem is a special case. However, the connections between global minimizers of the constrained {{\\ell}0} problem and its penalty problem have never been studied in a systematic way. This work provides a comprehensive investigation on optimal solutions of these two problems and their connections. We give detailed descriptions of optimal solutions of the two problems, including existence, stability with respect to the parameter, cardinality and strictness. In particular, we find that the optimal solution set of the penalty problem is piecewise constant with respect to the penalty parameter. Then we analyze in-depth the relationship between optimal solutions of the two problems. It is shown that, in the noisy case the least square penalty problem probably has no common optimal solutions with the constrained {{\\ell}0} problem for any penalty parameter. Under a mild condition on the penalty function, we establish that the penalty problem has the same optimal solution set as the constrained {{\\ell}0} problem when the penalty parameter is sufficiently large. Based on the conditions, we further propose exact penalty problems for the constrained {{\\ell}0} problem. Finally, we present a numerical example to illustrate our main theoretical results.
Heat-transfer tests of aqueous ethylene glycol solutions in an electrically heated tube
NASA Technical Reports Server (NTRS)
Bernardo, Everett; Eian, Carroll S
1945-01-01
As part of an investigation of the cooling characteristics of liquid-cooled engines, tests were conducted with an electrically heated single-tube heat exchanger to determine the heat-transfer characteristics of an-e-2 ethylene glycol and other ethylene glycol-water mixtures. Similar tests were conducted with water and commercial butanol (n-butyl alcohol) for check purposes. The results of tests conducted at an approximately constant liquid-flow rate of 0.67 pound per second (Reynolds number, 14,500 to 112,500) indicate that at an average liquid temperature 200 degrees f, the heat-transfer coefficients obtained using water, nominal (by volume) 30 percent-70 percent and 70 percent-30 percent glycol-water mixtures are approximately 3.8, 2.8, and 1.4 times higher, respectively, than the heat-transfer coefficients obtained using an-e-2 ethylene glycol.
The Lunar Internal Structure Model: Problems and Solutions
NASA Astrophysics Data System (ADS)
Nefedyev, Yuri; Gusev, Alexander; Petrova, Natalia; Varaksina, Natalia
decomposition of gravitational field of the Moon of members up to 165th order with a high degree of accuracy. Judging from the given data, the distinctive feature of the Moon’s gravitational field is that harmonics of the third and even the fourth order are comparable with harmonics of the second order, except for member J2. General conclusion: according to recent data, the true figure of the Moon is much more complex than a three-axis ellipsoid. Gravitational field and dynamic figure of the multilayered Moon: One of the main goals of selenodesy is the study of a dynamic figure of the Moon which determines distribution of the mass within the Moon’s body. A dynamic figure is shaped by the inertia ellipsoid set by values of resultant moments of inertia of the Moon A, B, C and their orientation in space. Selenoid satellites (SS) open new and most perspective opportunities in the study of gravitational field and the Moon’s figure. SSs “Moon 10”, “Apollo”, “Clementine”, “Lunar Prospector” trajectory tracking data processing has allowed for identification of coefficients in decomposition of gravitational field of the Moon of members up to 165th order with a high degree of accuracy. Judging from the given data, the distinctive feature of the Moon’s gravitational field is that harmonics of the third and even the fourth order are comparable with harmonics of the second order. Difference from zero of c-coefficients proves asymmetry of gravitational fields on the visible and invisible sides of the Moon. As a first attempt at solving the problem, the report presents the survey of internal structure of the Moon, tabulated values of geophysical parameters and geophysical profile of the Moon, including liquid lunar core, analytical solution of Clairaut’s equation for the two-layer model of the Moon; mathematical and bifurcational analysis of solution based on physically justified task options; original debugged software in VBA programming language for computer
Finite element solution of optimal control problems with state-control inequality constraints
NASA Technical Reports Server (NTRS)
Bless, Robert R.; Hodges, Dewey H.
1992-01-01
It is demonstrated that the weak Hamiltonian finite-element formulation is amenable to the solution of optimal control problems with inequality constraints which are functions of both state and control variables. Difficult problems can be treated on account of the ease with which algebraic equations can be generated before having to specify the problem. These equations yield very accurate solutions. Owing to the sparse structure of the resulting Jacobian, computer solutions can be obtained quickly when the sparsity is exploited.
Finite element solution of optimal control problems with state-control inequality constraints
NASA Technical Reports Server (NTRS)
Bless, Robert R.; Hodges, Dewey H.
1992-01-01
It is demonstrated that the weak Hamiltonian finite-element formulation is amenable to the solution of optimal control problems with inequality constraints which are functions of both state and control variables. Difficult problems can be treated on account of the ease with which algebraic equations can be generated before having to specify the problem. These equations yield very accurate solutions. Owing to the sparse structure of the resulting Jacobian, computer solutions can be obtained quickly when the sparsity is exploited.
Asymptotic solution of the problem for a thin axisymmetric cavern
NASA Technical Reports Server (NTRS)
Serebriakov, V. V.
1973-01-01
The boundary value problem which describes the axisymmetric separation of the flow around a body by a stationary infinite stream is considered. It is understood that the cavitation number varies over the length of the cavern. Using the asymptotic expansions for the potential of a thin body, the orders of magnitude of terms in the equations of the problem are estimated. Neglecting small quantities, a simplified boundary value problem is obtained.
NASA Astrophysics Data System (ADS)
Chang, Hung-Chieh; Lin, Pei-Chun
2014-02-01
Economic dispatch is the short-term determination of the optimal output from a number of electricity generation facilities to meet the system load while providing power. As such, it represents one of the main optimization problems in the operation of electrical power systems. This article presents techniques to substantially improve the efficiency of the canonical coordinates method (CCM) algorithm when applied to nonlinear combined heat and power economic dispatch (CHPED) problems. The improvement is to eliminate the need to solve a system of nonlinear differential equations, which appears in the line search process in the CCM algorithm. The modified algorithm was tested and the analytical solution was verified using nonlinear CHPED optimization problems, thereby demonstrating the effectiveness of the algorithm. The CCM methods proved numerically stable and, in the case of nonlinear programs, produced solutions with unprecedented accuracy within a reasonable time.
Solution of the minimum time-to-climb problem by matched asymptotic expansions
NASA Technical Reports Server (NTRS)
Ardema, M. D.
1976-01-01
Application of singular perturbation techniques to trajectory optimization problems of flight mechanics is discussed. The method of matched asymptotic expansions is used to obtain an approximate solution to the aircraft minimum time-to-climb problem. Outer, boundary-layer, and composite solutions are obtained to zeroth and first orders. A stability criterion is derived for the zeroth-order boundary-layer solutions (the theory requires a form of boundary-layer stability). A numerical example is considered for which it is shown that the stability criterion is satisfied and a useful numerical solution is obtained. The zeroth-order solution proves to be a poor approximation, but the first-order solution gives a good approximation for both the trajectory and the minimum time-to-climb. The computational cost of the singular perturbation solution is considerably less than that of a steepest descent solution. Thus singular perturbation methods appear to be promising for the solution of optimal control problems.
Verification of high-order mixed FEM solution of transient Magnetic diffusion problems
Rieben, R; White, D A
2005-05-12
We develop and present high order mixed finite element discretizations of the time dependent electromagnetic diffusion equations for solving eddy current problems on 3D unstructured grids. The discretizations are based on high order H(grad), H(curl) and H(div) conforming finite element spaces combined with an implicit and unconditionally stable generalized Crank-Nicholson time differencing method. We develop three separate electromagnetic diffusion formulations, namely the E (electric field), H (magnetic field) and the A-{phi} (potential) formulations. For each formulation, we also provide a consistent procedure for computing the secondary variables F (current flux density) and B (magnetic flux density), as these fields are required for the computation of electromagnetic force and heating terms. We verify the error convergence properties of each formulation via a series of numerical experiments on canonical problems with known analytic solutions. The key result is that the different formulations are equally accurate, even for the secondary variables J and B, and hence the choice of which formulation to use depends mostly upon relevance of the Natural and Essential boundary conditions to the problem of interest. In addition, we highlight issues with numerical verification of finite element methods which can lead to false conclusions on the accuracy of the methods.
Pavlenko, V N; Potapov, D K
2015-09-30
This paper is concerned with the existence of semiregular solutions to the Dirichlet problem for an equation of elliptic type with discontinuous nonlinearity and when the differential operator is not assumed to be formally self-adjoint. Theorems on the existence of semiregular (positive and negative) solutions for the problem under consideration are given, and a principle of upper and lower solutions giving the existence of semiregular solutions is established. For positive values of the spectral parameter, elliptic spectral problems with discontinuous nonlinearities are shown to have nontrivial semiregular (positive and negative) solutions. Bibliography: 32 titles.
Numerical Solution of Optimal Control Problem under SPDE Constraints
2011-10-14
equations, Advances in Com- putational Mathematics. Vol. 33, 215–230, (2010). [3] Feng Bao, Yanzhao Cao and Weidong Zhao, Numerical solutions for forward...Visiting Scholar, Zhongshan University, China 4 Publications 1 Feng Bao, Yanzhao Cao and Weidong Zhao, Numerical solutions for forward backward doubly...Li Yin , Spectral method for nonlinear stochastic partial differ- ential equations of elliptic type, accepted by Numer. Math. Theo. Meth. App., Vol. 4
NASA Astrophysics Data System (ADS)
Inaba, Hideo; Morita, Shin-Ichi
The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.
Transdisciplinary Variation in Engineering Curricula. Problems and Means for Solutions
ERIC Educational Resources Information Center
Jakobsen, Arne; Bucciarelli, Louis L.
2007-01-01
An essential difficulty in solving practical problems that are not like the ones a student has solved before is discerning the core of the problem. It is claimed that discernment has to be trained by variation--by varying the context of the assignments in which students have to identify and grasp their "underlying form". A decisive…
Problems and Solutions Related to College Students' Belief
ERIC Educational Resources Information Center
Zhang, Jinming
2008-01-01
With China staying in its social transition period, its changes in economy, politics and culture have influenced college students' thought to a large extent. Currently, in spite of the healthy and upward mainstream thought among college students, there are also some problems. This article elaborates on the problems and manifestations in college…
Auditing Management Practices in Schools: Recurring Communication Problems and Solutions
ERIC Educational Resources Information Center
Zwijze-Koning, Karen H.; de Jong, Menno D. T.
2009-01-01
Purpose: Over the past ten years, most Dutch high schools have been confronted with mergers, curriculum reforms, and managerial changes. As a result, the pressure on the schools' communication systems has increased and several problems have emerged. This paper aims to examine recurring clusters of communication problems in high schools.…
Transdisciplinary Variation in Engineering Curricula. Problems and Means for Solutions
ERIC Educational Resources Information Center
Jakobsen, Arne; Bucciarelli, Louis L.
2007-01-01
An essential difficulty in solving practical problems that are not like the ones a student has solved before is discerning the core of the problem. It is claimed that discernment has to be trained by variation--by varying the context of the assignments in which students have to identify and grasp their "underlying form". A decisive…
Solutions of inverse problems for biodegradation of xenobiotic polymers
NASA Astrophysics Data System (ADS)
Watanabe, Masaji; Kawai, Fusako
2016-02-01
Mathematical techniques are applied to a microbial depolymerization process. A mathematical model for the transition of the weight distribution and the microbial population is described. Inverse problems for a molecular factor and a time factor of a degradation rate are derived. Numerical techniques to solve the inverse problems are illustrated, and numerical results are presented.
Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region
NASA Astrophysics Data System (ADS)
Kaji, Masao; Furukawa, Masahiro; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko
A theoretical prediction model of the boiling heat transfer coefficient in the subcooled region for water and lithium bromide aqueous solution flowing in a rectangular channel is proposed. In the present heat transfer model, a heat flux is assumed to consist of both the forced convective and the boiling effect components. The forced convective component is evaluated from the empirical correlation of convective heat transfer coefficient for single-phase flow considering the effect of increase of liquid velocity due to net vapor generation. Empirical correlations for determining the heat flux due to the boiling effect and the quality at the onset point of net vapor generation are obtained from the data presented in the first report1). Agreement between the present theoretical prediction and the experimental data is satisfactorily good both for water and lithium bromide aqueous solution.
Solar-powered saline sorbent-solution heat pump/storage system
NASA Astrophysics Data System (ADS)
Robison, H.; Houston, S.
Coastal Energy Laboratory Chemical Heat Pump (CEL-CHEAP) is a redesigned open-cycle liquid desiccant air conditioner. Heat is discharged to shallow-well water by dehumidification-humidification for cooling and extracted by humidification-dehumidification for heating. Direct solar radiation concentrates the desiccant. For continuous operation, a small uninsulated tank stores concentrated solution. This chemical heat pump needs no mechanical compressor, condenser, vacuum system, or pressure system. The collector-regenerators are inexpensive. The refrigerant is water and the desiccant is calcium chloride. First cost and operating expenses are very low.
Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region
NASA Astrophysics Data System (ADS)
Furukawa, Masahiro; Kaji, Masao; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko
To improve the thermal performance of high temperature generator of absorption chiller/heater, heat transfer characteristics of flow boiling of lithium bromide aqueous solution in the subcooled region were experimentally investigated. Experiments were made for water and lithium bromide aqueous solution flowing in a rectangular channel (5 mm × 20 mm cross section) with one side wall heated. Boiling onset quality of lithium bromide aqueous solution is greater than that of water. The heat transfer coefficient of lithium bromide aqueous solution is about a half of that of water under the same experimental conditions of inlet velocity and heat flux. The experimental data of heat transfer coefficient for water are compared with the empirical correlation of Thom et al.11) and a fairly good agreement is obtained. The predictive calculations by the method of Sekoguchi et al.12) are compared with the data for water and lithium bromide aqueous solution. Agreement between them is good for water, while the results for lithium bromide aqueous solution are not satisfactory.
Existence and non-uniqueness of similarity solutions of a boundary layer problem
NASA Technical Reports Server (NTRS)
Hussaini, M. Y.; Lakin, W. D.
1984-01-01
A Blasius boundary value problem with inhomogeneous lower boundary conditions f(0) = 0 and f'(0) = - lambda with lambda strictly positive was considered. The Crocco variable formulation of this problem has a key term which changes sign in the interval of interest. It is shown that solutions of the boundary value problem do not exist for values of lambda larger than a positive critical value lambda. The existence of solutions is proven for 0 lambda lambda by considering an equivalent initial value problem. It is found however that for 0 lambda lambda, solutions of the boundary value problem are nonunique. Physically, this nonuniqueness is related to multiple values of the skin friction.
Existence and non-uniqueness of similarity solutions of a boundary-layer problem
NASA Technical Reports Server (NTRS)
Hussaini, M. Y.; Lakin, W. D.
1986-01-01
A Blasius boundary value problem with inhomogeneous lower boundary conditions f(0) = 0 and f'(0) = - lambda with lambda strictly positive was considered. The Crocco variable formulation of this problem has a key term which changes sign in the interval of interest. It is shown that solutions of the boundary value problem do not exist for values of lambda larger than a positive critical value lambda. The existence of solutions is proven for 0 lambda lambda by considering an equivalent initial value problem. It is found however that for 0 lambda lambda, solutions of the boundary value problem are nonunique. Physically, this nonuniqueness is related to multiple values of the skin friction.
NASA Astrophysics Data System (ADS)
Lambert, A. J. D.; Gupta, Surendra M.
2005-11-01
This paper deals with disassembly sequencing problems subjected to sequence dependent disassembly costs. We present a heuristic and an iterative method based on partial branch and bound concept to solve such problems. Since heuristic methods intrinsically generate suboptimum solutions, we compared the heuristically obtained solutions with the exact solutions to see if they are reasonably good or not. This process, however, is limited to small or perhaps medium sized problems only as the required CPU time for exact methods tends to increase exponentially with the problem size. For the problems tested, we observed that the methods described in this paper generate surprisingly good results using almost negligible amount of CPU time.
Glass, Micheal W.; Hogan, Roy E., Jr.; Gartling, David K.
2010-03-01
The need for the engineering analysis of systems in which the transport of thermal energy occurs primarily through a conduction process is a common situation. For all but the simplest geometries and boundary conditions, analytic solutions to heat conduction problems are unavailable, thus forcing the analyst to call upon some type of approximate numerical procedure. A wide variety of numerical packages currently exist for such applications, ranging in sophistication from the large, general purpose, commercial codes, such as COMSOL, COSMOSWorks, ABAQUS and TSS to codes written by individuals for specific problem applications. The original purpose for developing the finite element code described here, COYOTE, was to bridge the gap between the complex commercial codes and the more simplistic, individual application programs. COYOTE was designed to treat most of the standard conduction problems of interest with a user-oriented input structure and format that was easily learned and remembered. Because of its architecture, the code has also proved useful for research in numerical algorithms and development of thermal analysis capabilities. This general philosophy has been retained in the current version of the program, COYOTE, Version 5.0, though the capabilities of the code have been significantly expanded. A major change in the code is its availability on parallel computer architectures and the increase in problem complexity and size that this implies. The present document describes the theoretical and numerical background for the COYOTE program. This volume is intended as a background document for the user's manual. Potential users of COYOTE are encouraged to become familiar with the present report and the simple example analyses reported in before using the program. The theoretical and numerical background for the finite element computer program, COYOTE, is presented in detail. COYOTE is designed for the multi-dimensional analysis of nonlinear heat conduction problems
The concentration effect at nonisothermal nucleation under conditions of solid-solution heating
NASA Astrophysics Data System (ADS)
Ashkalunin, A. L.; Valov, P. M.; Derkacheva, O. Yu.; Leiman, V. I.; Maksimov, V. M.
2017-06-01
The influence of the heating rate of a solid solution up to the temperature of isothermal annealing on the distribution of CuCl particles by radii has been studied using the example of a solid solution of CuCl in glass. The study of changes in the distribution of particle radii in the CuCl phase has been performed using exciton-thermal analysis. It has been found that, with slow (60 min) heating of the sample to 650°C, the concentration of nucleates in the CuCl phase first increases rapidly and, then, the concentration decreases. The decrease in concentration is explained by the rapid growth of the critical radius with temperature and depletion of the solution. As follows from numerical simulation, the nucleation in a solution of CuCl in glass under conditions of slow heating is in good agreement with the experimental data.
An exact closed form solution for constant area compressible flow with friction and heat transfer
NASA Technical Reports Server (NTRS)
Sturas, J. I.
1971-01-01
The well-known differential equation for the one-dimensional flow of a compressible fluid with heat transfer and wall friction has no known solution in closed form for the general case. This report presents a closed form solution for the special case of constant heat flux per unit length and constant specific heat. The solution was obtained by choosing the square of a dimensionless flow parameter as one of the independent variables to describe the flow. From this exact solution, an approximate simplified form is derived that is applicable for predicting subsonic flow performance characteristics for many types of constant area passages in internal flow. The data included in this report are considered sufficiently accurate for use as a guide in analyzing and designing internal gas flow systems.
ERIC Educational Resources Information Center
Rebello, Carina M.
2012-01-01
This study explored the effects of alternative forms of argumentation on undergraduates' physics solutions in introductory calculus-based physics. A two-phase concurrent mixed methods design was employed to investigate relationships between undergraduates' written argumentation abilities, conceptual quality of problem solutions, as well…
Innovative Divertor Development to Solve the Plasma Heat-Flux Problem
Rognlien, T; Ryutov, D; Makowski, M; Soukhanovskii, V; Umansky, M; Cohen, R; HIll, D; Joseph, I
2009-02-26
Large, localized plasma heat exhaust continues to be one of the critical problems for the development of tokamak fusion reactors. Excessive heat flux erodes and possibly melts plasma-facing materials, thereby dramatically shortening their lifetime and increasing the impurity contamination of the core plasma. A detailed assessment by the ITER team for their divertor has revealed substantial limitations on the operational space imposed by the divertor performance. For a fusion reactor, the problem becomes worse in that the divertor must accommodate 20% of the total fusion power (less any broadly radiated loss), while not allowing excess buildup of tritium in the walls nor excessive impurity production. This is an extremely challenging set of problems that must be solved for fusion to succeed as a power source; it deserves a substantial research investment. Material heat-flux constraints: Results from present-day tokamaks show that there are two major limitations of peak plasma heat exhaust. The first is the continuous flow of power to the divertor plates and nearby surfaces that, for present technology, is limited to 10-20 MW/m{sup 2}. The second is the transient peak heat-flux that can be tolerated in a short time, {tau}{sub m}, before substantial ablation and melting of the surface occurs; such common large transient events are Edge Localized Mode (ELMs) and disruptions. The material limits imposed by these events give a peak energy/{tau}{sub m}{sup 1/2} parameter of {approx} 40 MJ/m{sup 2}s{sup 1/2} [1]. Both the continuous and transient limits can be approached by input powers in the largest present-day devices, and future devices are expected to substantially exceed the limits unless a solution can be found. Since the early 90's LLNL has developed the analytic and computational foundation for analyzing divertor plasmas, and also suggested and studied a number of solid and liquid material concepts for improving divertor/wall performance, with the most recent
New numerical methods for open-loop and feedback solutions to dynamic optimization problems
NASA Astrophysics Data System (ADS)
Ghosh, Pradipto
The topic of the first part of this research is trajectory optimization of dynamical systems via computational swarm intelligence. Particle swarm optimization is a nature-inspired heuristic search method that relies on a group of potential solutions to explore the fitness landscape. Conceptually, each particle in the swarm uses its own memory as well as the knowledge accumulated by the entire swarm to iteratively converge on an optimal or near-optimal solution. It is relatively straightforward to implement and unlike gradient-based solvers, does not require an initial guess or continuity in the problem definition. Although particle swarm optimization has been successfully employed in solving static optimization problems, its application in dynamic optimization, as posed in optimal control theory, is still relatively new. In the first half of this thesis particle swarm optimization is used to generate near-optimal solutions to several nontrivial trajectory optimization problems including thrust programming for minimum fuel, multi-burn spacecraft orbit transfer, and computing minimum-time rest-to-rest trajectories for a robotic manipulator. A distinct feature of the particle swarm optimization implementation in this work is the runtime selection of the optimal solution structure. Optimal trajectories are generated by solving instances of constrained nonlinear mixed-integer programming problems with the swarming technique. For each solved optimal programming problem, the particle swarm optimization result is compared with a nearly exact solution found via a direct method using nonlinear programming. Numerical experiments indicate that swarm search can locate solutions to very great accuracy. The second half of this research develops a new extremal-field approach for synthesizing nearly optimal feedback controllers for optimal control and two-player pursuit-evasion games described by general nonlinear differential equations. A notable revelation from this development
Offshore asphaltene and wax deposition: Problems/solutions
Leontaritis, K.J. |
1996-05-01
Many production facilities around the world suffer from either asphaltene or wax deposition. Such problems seriously threaten economic production from many offshore reservoirs due to the high cost of remedial measures. Offshore facilities are especially susceptible to such deposition for a number of reasons. This article presents ideas and methodologies on how to predict, diagnose, prevent, or mitigate problems caused by organic deposition in offshore production facilities. In one facility where these ideas were put to use, despite the debilitating magnitude of the problems, the field has been produced for more than 14 years with minimum environmental impact. Principal conclusions developed are discussed in this paper.
NASA Technical Reports Server (NTRS)
Bauld, N. R., Jr.; Goree, J. G.
1983-01-01
The accuracy of the finite difference method in the solution of linear elasticity problems that involve either a stress discontinuity or a stress singularity is considered. Solutions to three elasticity problems are discussed in detail: a semi-infinite plane subjected to a uniform load over a portion of its boundary; a bimetallic plate under uniform tensile stress; and a long, midplane symmetric, fiber reinforced laminate subjected to uniform axial strain. Finite difference solutions to the three problems are compared with finite element solutions to corresponding problems. For the first problem a comparison with the exact solution is also made. The finite difference formulations for the three problems are based on second order finite difference formulas that provide for variable spacings in two perpendicular directions. Forward and backward difference formulas are used near boundaries where their use eliminates the need for fictitious grid points.
NASA Astrophysics Data System (ADS)
Inaba, Hideo; Aly, Wael I. A.; Haruki, Naoto; Horibe, Akihiko
2005-08-01
The reduction characteristic of turbulent drag and heat transfer of drag reduction surfactant solution flowing in a helically coiled pipe were experimentally investigated. The drag reduction surfactant used in the present study was the amine oxide type nonionic surfactant of oleyldihydroxyethylamineoxide (ODEAO, C22H45NO3=371). The zwitterion surfactant of cetyldimethylaminoaciticacidbetaine (CDMB, C20H41NO2=327) was added by 10% to the ODEAO solution in order to avoid the chemical degradation of ODEAO by ionic impurities in a test tape water. The experiments of flow drag and heat transfer reduction were carried out in the helically coiled pipe of coil to pipe diameter ratio of 37.5 and the helically coiled pipe length to pipe diameter of 1180.5 (pipe diameter of 14.4 mm) at various concentrations, temperatures and flow velocities of the ODEAO surfactant solution. The ODEAO solution showed a non-Newtonian behavior at high concentration of the ODEAO. From the experimental results, it was observed that the friction factor of the ODEAO surfactant solution flowing through the coiled pipe was decreased to a great extent in comparison with water as a Newtonian fluid in the turbulent flow region. Heat transfer measurements for water and the ODEAO solution were performed in both laminar and turbulent flow regions under the uniform heat flux boundary condition. The heat transfer coefficients for the ODEAO solution flow were the same as water flow in the laminar region. On the other hand, heat transfer reduction of the ODEAO solution flow was remarkedly reduced as compared with that of the water flow in the turbulent flow region.
Exact solution to the averaging problem in cosmology.
Wiltshire, David L
2007-12-21
The exact solution of a two-scale Buchert average of the Einstein equations is derived for an inhomogeneous universe that represents a close approximation to the observed universe. The two scales represent voids, and the bubble walls surrounding them within which clusters of galaxies are located. As described elsewhere [New J. Phys. 9, 377 (2007)10.1088/1367-2630/9/10/377], apparent cosmic acceleration can be recognized as a consequence of quasilocal gravitational energy gradients between observers in bound systems and the volume-average position in freely expanding space. With this interpretation, the new solution presented here replaces the Friedmann solutions, in representing the average evolution of a matter-dominated universe without exotic dark energy, while being observationally viable.
Percutaneous devices: a review of applications, problems and possible solutions.
Affeld, Klaus; Grosshauser, Johannes; Goubergrits, Leonid; Kertzscher, Ulrich
2012-07-01
Percutaneous devices enable the transfer of mass, energy and forces through the skin. There is a wide clinical need for this, which is not likely to decrease or disappear. The emerging new artificial organs, such as wearable kidneys or lungs, will be in increased demand in the future. Any application lasting longer than days or weeks is endangered by infections entering the body via the exit site. The only carefree solution that has been found is for an exit site placed on the skull, where it can be securely immobilized. For the majority of the locations on the abdomen or chest, no solution for an infection-free device has been found. A solution may be possible with a better understanding of the physiology of keratinocytes as a barrier for microbes.
Inverse transient heat conduction problems and identification of thermal parameters
NASA Astrophysics Data System (ADS)
Atchonouglo, K.; Banna, M.; Vallée, C.; Dupré, J.-C.
2008-04-01
This work deals with the estimation of polymers properties. An inverse analysis based on finite element method is applied to identify simultaneously the constants thermal conductivity and heat capacity per unit volume. The inverse method algorithm constructed is validated from simulated transient temperature recording taken at several locations on the surface of the solid. Transient temperature measures taped with infrared camera on polymers were used for identifying the thermal properties. The results show an excellent agreement between manufacturer and identified values.
Interpersonal problems and personality: using three factor solutions.
McDonald, Michelle J; Linden, Paul D
2003-10-01
Attempting to bridge the gap between psychotherapy research on interpersonal discord and personality research on factors of normal and abnormal personality, the present study uses personality factors to predict interpersonal problems. Eysenck's P-E-N (Psychoticism-Extraversion-Neuroticism) model of personality and its correspondent index, the Eysenck Personality Questionnaire-Revised is used as a schema from which to conceptualize and measure personality. Horowitz's Inventory of Interpersonal Problems, which includes six problems commonly reported by psychotherapy patients at intake (hard to be assertive, hard to be submissive, hard to be intimate, hard to be sociable, too controlling, and too responsible), was used as an index of interpersonal distress. Hierarchical multiple regression, in which the most significant predictor was entered into the equation first, indicate significant prediction of various problems by the personality factors considered here. Results are discussed in the context of interpersonal theory.
The Highest Battlefield of the World : Medical Problems and Solutions.
Jindal, A K
2009-04-01
The Indian Armed Forces Medical Services has been engaged in providing medical to the soldiers serving on Siachen Glacier for the last 25 years. This paper attempts to highlight the medical problems faced by troops on the world's highest battlefield as perceived by a medical officer located on the forward most medical echelon on Siachen Glacier. The medical problems on the glacier include high altitude pulmonary oedema, acute mountain sickness, frost bite chilblains, hypothermia, snow blindness, injury non enemy action due to avalanches, crevasses and fires, carbon monoxide poisoning and problems in disposal of nightsoil. A large number of problems are taken care of by following a well documented acclimatisation drill. However under such conditions providing medical support is a difficult task and requires innovations and improvisations entailing a high degree of mental mobility on the part of medical commanders and the Regimental Medical Officers located on the forward posts.
Hiding quiet solutions in random constraint satisfaction problems
Zdeborova, Lenka; Krzakala, Florent
2008-01-01
We study constraint satisfaction problems on the so-called planted random ensemble. We show that for a certain class of problems, e.g., graph coloring, many of the properties of the usual random ensemble are quantitatively identical in the planted random ensemble. We study the structural phase transitions and the easy-hard-easy pattern in the average computational complexity. We also discuss the finite temperature phase diagram, finding a close connection with the liquid-glass-solid phenomenology.
Workplace problems and solutions for employees with chronic diseases.
Varekamp, I; van Dijk, F J H
2010-06-01
While many employees who have a chronic disease manage their jobs well, others are hampered in work performance, experience work-related problems and are at risk for job loss. To identify the practical and psychosocial barriers recognized by employees with chronic disease who experience work-related problems and to examine preferred work accommodations. A questionnaire was sent by mail and completed by current workers who have a chronic disease and experience serious problems at work. One hundred and twenty-two employees participated in this study. On average, they had been ill for 10 years and 44% had more than one disease. The most outstanding work-related problems were psychosocial, including work-home interference and a lack of acceptance of the chronic disease. Performing and finishing work tasks and social relationships with supervisors or colleagues were also felt to be slightly problematic. The most preferred work accommodations included fewer work hours, working from home, a slower work pace and more autonomy in planning work tasks. Almost three-quarters of the respondents were so fatigued that they were at risk of sickness absence or work disability. A chronic physical disease may lead to both practical and psychosocial problems and serious fatigue. Managing psychosocial problems may decrease fatigue.
Solution Approaches for Network Flow Problems with Multiple Criteria,
1979-12-01
34 Journal of Mathematical Analysis and Applications , 69, 2 (1979) 283-303. 12. R. Steuer and A. Schuler, "An Interactive Multiple-Objective Linear...Solutions in Linear Cases and a Multicriteria Siuplex Method," Journal of Mathematical Analysis and Applications , 49, 2 (1975) 430-468. 16. M. Zeleny, Linear
Hiring and Recruitment Practices in Academic Libraries: Problems and Solutions.
ERIC Educational Resources Information Center
Raschke, Gregory K.
2003-01-01
Academic libraries need to change their recruiting and hiring procedures to stay competitive in today's changing marketplace. To be more competitive and effective in their recruitment and hiring processes, academic libraries must foster manageable internal solutions, look to other professions for effective hiring techniques and models, and employ…
PDS Work at a Small University: Solutions to Common Problems
ERIC Educational Resources Information Center
Mills, Lynne
2010-01-01
Small universities deal with two primary issues when beginning to use the Professional Development School model: Adequate Funding and Faculty Support. Possible solutions are discussed, including ways to provide adequate funding through grants, enrichment/tutoring programs, reallocation of existing funds, and university priority money, as well as…
New-Age Solutions to Old Age Problems?
ERIC Educational Resources Information Center
World of Work, 2002
2002-01-01
As people live longer, produce fewer children, and retire earlier, the ratio of older people to working people is growing. This creates an imbalance in the replenishment of pension funds. Solutions include promoting training and flexibility for older workers, ending discrimination, and changing attitudes thorough education and information. (JOW)
Hiring and Recruitment Practices in Academic Libraries: Problems and Solutions.
ERIC Educational Resources Information Center
Raschke, Gregory K.
2003-01-01
Academic libraries need to change their recruiting and hiring procedures to stay competitive in today's changing marketplace. To be more competitive and effective in their recruitment and hiring processes, academic libraries must foster manageable internal solutions, look to other professions for effective hiring techniques and models, and employ…