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Sample records for population balance equation

  1. Analytical solution of population balance equation involving ...

    Indian Academy of Sciences (India)

    This paper presents an effective analytical simulation to solve population balance equation (PBE), involving particulate aggregation and breakage, by making use ... The domain part of the email address of all email addresses used by the office of Indian Academy of Sciences, including those of the staff, the journals, various ...

  2. Stochastic solution of population balance equations for reactor networks

    International Nuclear Information System (INIS)

    Menz, William J.; Akroyd, Jethro; Kraft, Markus

    2014-01-01

    This work presents a sequential modular approach to solve a generic network of reactors with a population balance model using a stochastic numerical method. Full-coupling to the gas-phase is achieved through operator-splitting. The convergence of the stochastic particle algorithm in test networks is evaluated as a function of network size, recycle fraction and numerical parameters. These test cases are used to identify methods through which systematic and statistical error may be reduced, including by use of stochastic weighted algorithms. The optimal algorithm was subsequently used to solve a one-dimensional example of silicon nanoparticle synthesis using a multivariate particle model. This example demonstrated the power of stochastic methods in resolving particle structure by investigating the transient and spatial evolution of primary polydispersity, degree of sintering and TEM-style images. Highlights: •An algorithm is presented to solve reactor networks with a population balance model. •A stochastic method is used to solve the population balance equations. •The convergence and efficiency of the reported algorithms are evaluated. •The algorithm is applied to simulate silicon nanoparticle synthesis in a 1D reactor. •Particle structure is reported as a function of reactor length and time

  3. An improved particle population balance equation in the continuum-slip regime

    Directory of Open Access Journals (Sweden)

    Xie Mingliang

    2016-01-01

    Full Text Available An improved moment model is proposed to solve the population balance equation for Brownian coagulation in the continuum-slip regime, and it reduces to a known one in open literature when the non-linear terms in the slip correction factor are ignored. The present model shows same asymptotic behavior as that in the continuum regime.

  4. Stochastic weighted particle methods for population balance equations with coagulation, fragmentation and spatial inhomogeneity

    International Nuclear Information System (INIS)

    Lee, Kok Foong; Patterson, Robert I.A.; Wagner, Wolfgang; Kraft, Markus

    2015-01-01

    Graphical abstract: -- Highlights: •Problems concerning multi-compartment population balance equations are studied. •A class of fragmentation weight transfer functions is presented. •Three stochastic weighted algorithms are compared against the direct simulation algorithm. •The numerical errors of the stochastic solutions are assessed as a function of fragmentation rate. •The algorithms are applied to a multi-dimensional granulation model. -- Abstract: This paper introduces stochastic weighted particle algorithms for the solution of multi-compartment population balance equations. In particular, it presents a class of fragmentation weight transfer functions which are constructed such that the number of computational particles stays constant during fragmentation events. The weight transfer functions are constructed based on systems of weighted computational particles and each of it leads to a stochastic particle algorithm for the numerical treatment of population balance equations. Besides fragmentation, the algorithms also consider physical processes such as coagulation and the exchange of mass with the surroundings. The numerical properties of the algorithms are compared to the direct simulation algorithm and an existing method for the fragmentation of weighted particles. It is found that the new algorithms show better numerical performance over the two existing methods especially for systems with significant amount of large particles and high fragmentation rates.

  5. Stochastic weighted particle methods for population balance equations with coagulation, fragmentation and spatial inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kok Foong [Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Patterson, Robert I.A.; Wagner, Wolfgang [Weierstrass Institute for Applied Analysis and Stochastics, Mohrenstraße 39, 10117 Berlin (Germany); Kraft, Markus, E-mail: mk306@cam.ac.uk [Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA (United Kingdom); School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459 (Singapore)

    2015-12-15

    Graphical abstract: -- Highlights: •Problems concerning multi-compartment population balance equations are studied. •A class of fragmentation weight transfer functions is presented. •Three stochastic weighted algorithms are compared against the direct simulation algorithm. •The numerical errors of the stochastic solutions are assessed as a function of fragmentation rate. •The algorithms are applied to a multi-dimensional granulation model. -- Abstract: This paper introduces stochastic weighted particle algorithms for the solution of multi-compartment population balance equations. In particular, it presents a class of fragmentation weight transfer functions which are constructed such that the number of computational particles stays constant during fragmentation events. The weight transfer functions are constructed based on systems of weighted computational particles and each of it leads to a stochastic particle algorithm for the numerical treatment of population balance equations. Besides fragmentation, the algorithms also consider physical processes such as coagulation and the exchange of mass with the surroundings. The numerical properties of the algorithms are compared to the direct simulation algorithm and an existing method for the fragmentation of weighted particles. It is found that the new algorithms show better numerical performance over the two existing methods especially for systems with significant amount of large particles and high fragmentation rates.

  6. Chemical Equation Balancing.

    Science.gov (United States)

    Blakley, G. R.

    1982-01-01

    Reviews mathematical techniques for solving systems of homogeneous linear equations and demonstrates that the algebraic method of balancing chemical equations is a matter of solving a system of homogeneous linear equations. FORTRAN programs using this matrix method to chemical equation balancing are available from the author. (JN)

  7. Exact solutions of the population balance equation including particle transport, using group analysis

    Science.gov (United States)

    Lin, Fubiao; Meleshko, Sergey V.; Flood, Adrian E.

    2018-06-01

    The population balance equation (PBE) has received an unprecedented amount of attention in recent years from both academics and industrial practitioners because of its long history, widespread use in engineering, and applicability to a wide variety of particulate and discrete-phase processes. However it is typically impossible to obtain analytical solutions, although in almost every case a numerical solution of the PBEs can be obtained. In this article, the symmetries of PBEs with homogeneous coagulation kernels involving aggregation, breakage and growth processes and particle transport in one dimension are found by direct solving the determining equations. Using the optimal system of one and two-dimensional subalgebras, all invariant solutions and reduced equations are obtained. In particular, an explicit analytical physical solution is also presented.

  8. State-dependent neutral delay equations from population dynamics.

    Science.gov (United States)

    Barbarossa, M V; Hadeler, K P; Kuttler, C

    2014-10-01

    A novel class of state-dependent delay equations is derived from the balance laws of age-structured population dynamics, assuming that birth rates and death rates, as functions of age, are piece-wise constant and that the length of the juvenile phase depends on the total adult population size. The resulting class of equations includes also neutral delay equations. All these equations are very different from the standard delay equations with state-dependent delay since the balance laws require non-linear correction factors. These equations can be written as systems for two variables consisting of an ordinary differential equation (ODE) and a generalized shift, a form suitable for numerical calculations. It is shown that the neutral equation (and the corresponding ODE--shift system) is a limiting case of a system of two standard delay equations.

  9. Stochastic weighted particle methods for population balance equations

    International Nuclear Information System (INIS)

    Patterson, Robert I.A.; Wagner, Wolfgang; Kraft, Markus

    2011-01-01

    Highlights: → Weight transfer functions for Monte Carlo simulation of coagulation. → Efficient support for single-particle growth processes. → Comparisons to analytic solutions and soot formation problems. → Better numerical accuracy for less common particles. - Abstract: A class of coagulation weight transfer functions is constructed, each member of which leads to a stochastic particle algorithm for the numerical treatment of population balance equations. These algorithms are based on systems of weighted computational particles and the weight transfer functions are constructed such that the number of computational particles does not change during coagulation events. The algorithms also facilitate the simulation of physical processes that change single particles, such as growth, or other surface reactions. Four members of the algorithm family have been numerically validated by comparison to analytic solutions to simple problems. Numerical experiments have been performed for complex laminar premixed flame systems in which members of the class of stochastic weighted particle methods were compared to each other and to a direct simulation algorithm. Two of the weighted algorithms have been shown to offer performance advantages over the direct simulation algorithm in situations where interest is focused on the larger particles in a system. The extent of this advantage depends on the particular system and on the quantities of interest.

  10. Systematic tools for chemical equation balancing

    International Nuclear Information System (INIS)

    Filby, E.E.; Idaho National Engineering Lab., Idaho Falls, ID; Idaho Univ., Idaho Falls, ID

    1989-01-01

    One of the most important skills that chemists and chemical engineers must develop is the ability to balance chemical equations. The normal first method taught is ''balancing by inspection'', which is sometimes explained as simply ''mental algebra.'' Every textbook surveyed for this paper presents equation balancing first as a matter of trial and error; this includes four very recently published books. Very little further guidance is provided until oxidation-reduction reactions must be balanced. The most commonly taught approaches for balancing, redox equations have been the oxidation state change and ion-electron methods. Unfortunately, redox reactions are usually treated as a new topic, and what the student has teamed about ''ordinary'' equations is of little or no help. All too often, these contradictions simply confuse and frustrate students, and equation balancing is relegated to the status of a black art. This is ironic because such,confusion and frustration is not necessary: Chemical equations can, in fact, be balanced by explicitly definable mathematical methods. The purpose of this paper is to outline the algebraic methods involved

  11. How Should Equation Balancing Be Taught?

    Science.gov (United States)

    Porter, Spencer K.

    1985-01-01

    Matrix methods and oxidation-number methods are currently advocated and used for balancing equations. This article shows how balancing equations can be introduced by a third method which is related to a fundamental principle, is easy to learn, and is powerful in its application. (JN)

  12. Student Understanding of Chemical Equation Balancing.

    Science.gov (United States)

    Yarroch, W. L.

    1985-01-01

    Results of interviews with high school chemistry students (N=14) during equation-solving sessions indicate that those who were able to construct diagrams consistent with notation of their balanced equation possessed good concepts of subscript and the balancing rule. Implications for chemistry teaching are discussed. (DH)

  13. Balance equations for a relativistic plasma. Pt. 1

    International Nuclear Information System (INIS)

    Hebenstreit, H.

    1983-01-01

    Relativistic power moments of the four-momentum are decomposed according to a macroscopic four-velocity. The thus obtained quantities are identified as relativistic generalization of the nonrelativistic orthogonal moments, e.g. diffusion flow, heat flow, pressure, etc. From the relativistic Boltzmann equation we then derive balance equations for these quantities. Explicit expressions for the relativistic mass conservation, energy balance, pressure balance, heat flow balance are presented. The weak relativistic limit is discussed. The derivation of higher order balance equations is sketched. (orig.)

  14. Balancing Chemical Equations.

    Science.gov (United States)

    Savoy, L. G.

    1988-01-01

    Describes a study of students' ability to balance equations. Answers to a test on this topic were analyzed to determine the level of understanding and processes used by the students. Presented is a method to teach this skill to high school chemistry students. (CW)

  15. Improved population balance model for straining-dominant deep bed filtration using network calculations

    DEFF Research Database (Denmark)

    Yuan, Hao; You, Zhenjiang; Shapiro, Alexander

    2013-01-01

    Colloidal-suspension flow in porous media is modelled simultaneously by the large scale population balance equations and by the microscale network model. The phenomenological parameter of the correlation length in the population balance model is determined from the network modelling. It is found...... out that the correlation length in the population balance model depends on the particle size. This dependency calculated by two-dimensional network has the same tendency as that obtained from the laboratory tests in engineered porous media....

  16. Insights: A New Method to Balance Chemical Equations.

    Science.gov (United States)

    Garcia, Arcesio

    1987-01-01

    Describes a method designed to balance oxidation-reduction chemical equations. Outlines a method which is based on changes in the oxidation number that can be applied to both molecular reactions and ionic reactions. Provides examples and delineates the steps to follow for each type of equation balancing. (TW)

  17. Macroscopic balance equations for two-phase flow models

    International Nuclear Information System (INIS)

    Hughes, E.D.

    1979-01-01

    The macroscopic, or overall, balance equations of mass, momentum, and energy are derived for a two-fluid model of two-phase flows in complex geometries. These equations provide a base for investigating methods of incorporating improved analysis methods into computer programs, such as RETRAN, which are used for transient and steady-state thermal-hydraulic analyses of nuclear steam supply systems. The equations are derived in a very general manner so that three-dimensional, compressible flows can be analysed. The equations obtained supplement the various partial differential equation two-fluid models of two-phase flow which have recently appeared in the literature. The primary objective of the investigation is the macroscopic balance equations. (Auth.)

  18. Seismic fatigue life evaluation of mechanical structures using energy balance equation

    International Nuclear Information System (INIS)

    Minagawa, Keisuke; Fujita, Satoshi; Kitamura, Seiji; Okamura, Shigeki

    2009-01-01

    Evaluation of seismic resistant performance for severe earthquakes is required, because of occurrence of earthquakes which exceed the design criteria. Additionally, quantitative evaluation of cumulative damage by earthquake is also required. In this study, the energy balance equation is applied to the evaluation. The energy balance equation expresses integral information of response, so that the energy balance equation is adequate for the evaluation of the influence of cumulative load such as seismic response. At first, vibration experiment that leads experimental model to fatigue failure by continuous vibration disturbance is conducted. As a result of the experiment, relation between fatigue failure and energy balance equation is confirmed. Then the relation is proved from the viewpoint of hysteresis energy, and consistency between energy balance equation and hysteresis energy is confirmed. Finally, we adopted cumulative damage rule to energy balance equation in order to expect the fatigue life under random waves that have various input acceleration. (author)

  19. BALANCER: A Computer Program for Balancing Chemical Equations.

    Science.gov (United States)

    Jones, R. David; Schwab, A. Paul

    1989-01-01

    Describes the theory and operation of a computer program which was written to balance chemical equations. Software consists of a compiled file of 46K for use under MS-DOS 2.0 or later on IBM PC or compatible computers. Additional specifications of courseware and availability information are included. (Author/RT)

  20. Automatic computation and solution of generalized harmonic balance equations

    Science.gov (United States)

    Peyton Jones, J. C.; Yaser, K. S. A.; Stevenson, J.

    2018-02-01

    Generalized methods are presented for generating and solving the harmonic balance equations for a broad class of nonlinear differential or difference equations and for a general set of harmonics chosen by the user. In particular, a new algorithm for automatically generating the Jacobian of the balance equations enables efficient solution of these equations using continuation methods. Efficient numeric validation techniques are also presented, and the combined algorithm is applied to the analysis of dc, fundamental, second and third harmonic response of a nonlinear automotive damper.

  1. Maximum Entropy Closure of Balance Equations for Miniband Semiconductor Superlattices

    Directory of Open Access Journals (Sweden)

    Luis L. Bonilla

    2016-07-01

    Full Text Available Charge transport in nanosized electronic systems is described by semiclassical or quantum kinetic equations that are often costly to solve numerically and difficult to reduce systematically to macroscopic balance equations for densities, currents, temperatures and other moments of macroscopic variables. The maximum entropy principle can be used to close the system of equations for the moments but its accuracy or range of validity are not always clear. In this paper, we compare numerical solutions of balance equations for nonlinear electron transport in semiconductor superlattices. The equations have been obtained from Boltzmann–Poisson kinetic equations very far from equilibrium for strong fields, either by the maximum entropy principle or by a systematic Chapman–Enskog perturbation procedure. Both approaches produce the same current-voltage characteristic curve for uniform fields. When the superlattices are DC voltage biased in a region where there are stable time periodic solutions corresponding to recycling and motion of electric field pulses, the differences between the numerical solutions produced by numerically solving both types of balance equations are smaller than the expansion parameter used in the perturbation procedure. These results and possible new research venues are discussed.

  2. A New Pseudoinverse Matrix Method For Balancing Chemical Equations And Their Stability

    International Nuclear Information System (INIS)

    Risteski, Ice B.

    2008-01-01

    In this work is given a new pseudoniverse matrix method for balancing chemical equations. Here offered method is founded on virtue of the solution of a Diophantine matrix equation by using of a Moore-Penrose pseudoinverse matrix. The method has been tested on several typical chemical equations and found to be very successful for the all equations in our extensive balancing research. This method, which works successfully without any limitations, also has the capability to determine the feasibility of a new chemical reaction, and if it is feasible, then it will balance the equation. Chemical equations treated here possess atoms with fractional oxidation numbers. Also, in the present work are introduced necessary and sufficient criteria for stability of chemical equations over stability of their extended matrices

  3. Teaching Population Balances for Chemical Engineering Students: Application to Granulation Processes

    Science.gov (United States)

    Bucala, Veronica; Pina, Juliana

    2007-01-01

    The population balance equation (PBE) is a useful tool to predict particle size distributions in granulation processes. When PBE is taught to advanced chemical engineering students, the internal coordinates (particle properties) are particularly hard to understand. In this paper, the flow of particles along different coordinates is carefully…

  4. Application of Gaussian cubature to model two-dimensional population balances

    Directory of Open Access Journals (Sweden)

    Bałdyga Jerzy

    2017-09-01

    Full Text Available In many systems of engineering interest the moment transformation of population balance is applied. One of the methods to solve the transformed population balance equations is the quadrature method of moments. It is based on the approximation of the density function in the source term by the Gaussian quadrature so that it preserves the moments of the original distribution. In this work we propose another method to be applied to the multivariate population problem in chemical engineering, namely a Gaussian cubature (GC technique that applies linear programming for the approximation of the multivariate distribution. Examples of the application of the Gaussian cubature (GC are presented for four processes typical for chemical engineering applications. The first and second ones are devoted to crystallization modeling with direction-dependent two-dimensional and three-dimensional growth rates, the third one represents drop dispersion accompanied by mass transfer in liquid-liquid dispersions and finally the fourth case regards the aggregation and sintering of particle populations.

  5. Balancing Chemical Equations: The Role of Developmental Level and Mental Capacity.

    Science.gov (United States)

    Niaz, Mansoor; Lawson, Anton E.

    1985-01-01

    Tested two hypotheses: (1) formal reasoning is required to balance simple one-step equations; and (2) formal reasoning plus sufficient mental capacity are required to balance many-step equations. Independent variables included intellectual development, mental capacity, and degree of field dependence/independence. With 25 subjects, significance was…

  6. Computer Applications in Balancing Chemical Equations.

    Science.gov (United States)

    Kumar, David D.

    2001-01-01

    Discusses computer-based approaches to balancing chemical equations. Surveys 13 methods, 6 based on matrix, 2 interactive programs, 1 stand-alone system, 1 developed in algorithm in Basic, 1 based on design engineering, 1 written in HyperCard, and 1 prepared for the World Wide Web. (Contains 17 references.) (Author/YDS)

  7. Efficient simulation of gas-liquid pipe flows using a generalized population balance equation coupled with the algebraic slip model

    KAUST Repository

    Icardi, Matteo; Ronco, Gianni; Marchisio, Daniele Luca; Labois, Mathieu

    2014-01-01

    The inhomogeneous generalized population balance equation, which is discretized with the direct quadrature method of moment (DQMOM), is solved to predict the bubble size distribution (BSD) in a vertical pipe flow. The proposed model is compared with a more classical approach where bubbles are characterized with a constant mean size. The turbulent two-phase flow field, which is modeled using a Reynolds-Averaged Navier-Stokes equation approach, is assumed to be in local equilibrium, thus the relative gas and liquid (slip) velocities can be calculated with the algebraic slip model, thereby accounting for the drag, lift, and lubrication forces. The complex relationship between the bubble size distribution and the resulting forces is described accurately by the DQMOM. Each quadrature node and weight represents a class of bubbles with characteristic size and number density, which change dynamically in time and space to preserve the first moments of the BSD. The predictions obtained are validated against previously published experimental data, thereby demonstrating the advantages of this approach for large-scale systems as well as suggesting future extensions to long piping systems and more complex geometries. © 2014 Elsevier Inc.

  8. Efficient simulation of gas-liquid pipe flows using a generalized population balance equation coupled with the algebraic slip model

    KAUST Repository

    Icardi, Matteo

    2014-09-01

    The inhomogeneous generalized population balance equation, which is discretized with the direct quadrature method of moment (DQMOM), is solved to predict the bubble size distribution (BSD) in a vertical pipe flow. The proposed model is compared with a more classical approach where bubbles are characterized with a constant mean size. The turbulent two-phase flow field, which is modeled using a Reynolds-Averaged Navier-Stokes equation approach, is assumed to be in local equilibrium, thus the relative gas and liquid (slip) velocities can be calculated with the algebraic slip model, thereby accounting for the drag, lift, and lubrication forces. The complex relationship between the bubble size distribution and the resulting forces is described accurately by the DQMOM. Each quadrature node and weight represents a class of bubbles with characteristic size and number density, which change dynamically in time and space to preserve the first moments of the BSD. The predictions obtained are validated against previously published experimental data, thereby demonstrating the advantages of this approach for large-scale systems as well as suggesting future extensions to long piping systems and more complex geometries. © 2014 Elsevier Inc.

  9. Modified harmonic balance method for the solution of nonlinear jerk equations

    Science.gov (United States)

    Rahman, M. Saifur; Hasan, A. S. M. Z.

    2018-03-01

    In this paper, a second approximate solution of nonlinear jerk equations (third order differential equation) can be obtained by using modified harmonic balance method. The method is simpler and easier to carry out the solution of nonlinear differential equations due to less number of nonlinear equations are required to solve than the classical harmonic balance method. The results obtained from this method are compared with those obtained from the other existing analytical methods that are available in the literature and the numerical method. The solution shows a good agreement with the numerical solution as well as the analytical methods of the available literature.

  10. Coupled force-balance and particle-occupation rate equations for high-field electron transport

    International Nuclear Information System (INIS)

    Lei, X. L.

    2008-01-01

    It is pointed out that in the framework of balance-equation approach, the coupled force-balance and particle-occupation rate equations can be used as a complete set of equations to determine the high-field transport of semiconductors in both strong and weak electron-electron interaction limits. We call to attention that the occupation rate equation conserves the total particle number and maintains the energy balance of the relative electron system, and there is no need to introduce any other term in it. The addition of an energy-drift term in the particle-occupation rate equation [Phys. Rev. B 71, 195205 (2005)] is physically inadequate for the violation of the total particle-number conservation and the energy balance. It may lead to a substantial unphysical increase of the total particle number by the application of a dc electric field

  11. A population balance equation model of aggregation dynamics in Taxus suspension cell cultures.

    Science.gov (United States)

    Kolewe, Martin E; Roberts, Susan C; Henson, Michael A

    2012-02-01

    The nature of plant cells to grow as multicellular aggregates in suspension culture has profound effects on bioprocess performance. Recent advances in the measurement of plant cell aggregate size allow for routine process monitoring of this property. We have exploited this capability to develop a conceptual model to describe changes in the aggregate size distribution that are observed over the course of a Taxus cell suspension batch culture. We utilized the population balance equation framework to describe plant cell aggregates as a particulate system, accounting for the relevant phenomenological processes underlying aggregation, such as growth and breakage. We compared model predictions to experimental data to select appropriate kernel functions, and found that larger aggregates had a higher breakage rate, biomass was partitioned asymmetrically following a breakage event, and aggregates grew exponentially. Our model was then validated against several datasets with different initial aggregate size distributions and was able to quantitatively predict changes in total biomass and mean aggregate size, as well as actual size distributions. We proposed a breakage mechanism where a fraction of biomass was lost upon each breakage event, and demonstrated that even though smaller aggregates have been shown to produce more paclitaxel, an optimum breakage rate was predicted for maximum paclitaxel accumulation. We believe this is the first model to use a segregated, corpuscular approach to describe changes in the size distribution of plant cell aggregates, and represents an important first step in the design of rational strategies to control aggregation and optimize process performance. Copyright © 2011 Wiley Periodicals, Inc.

  12. Quantum Mechanical Balance Equation Approach to Semiconductor Device Simulation

    National Research Council Canada - National Science Library

    Cui, Long

    1997-01-01

    This research project was focused on the development of a quantum mechanical balance equation based device simulator that can model advanced, compound, submicron devices, under all transport conditions...

  13. Best-fitting prediction equations for basal metabolic rate: informing obesity interventions in diverse populations.

    Science.gov (United States)

    Sabounchi, N S; Rahmandad, H; Ammerman, A

    2013-10-01

    Basal metabolic rate (BMR) represents the largest component of total energy expenditure and is a major contributor to energy balance. Therefore, accurately estimating BMR is critical for developing rigorous obesity prevention and control strategies. Over the past several decades, numerous BMR formulas have been developed targeted to different population groups. A comprehensive literature search revealed 248 BMR estimation equations developed using diverse ranges of age, gender, race, fat-free mass, fat mass, height, waist-to-hip ratio, body mass index and weight. A subset of 47 studies included enough detail to allow for development of meta-regression equations. Utilizing these studies, meta-equations were developed targeted to 20 specific population groups. This review provides a comprehensive summary of available BMR equations and an estimate of their accuracy. An accompanying online BMR prediction tool (available at http://www.sdl.ise.vt.edu/tutorials.html) was developed to automatically estimate BMR based on the most appropriate equation after user-entry of individual age, race, gender and weight.

  14. Balance equations for a viscous fluid from a Hamilton type variational principle

    International Nuclear Information System (INIS)

    Fierros Palacios, A.

    1992-01-01

    The partial differential field equations for any viscous fluid are obtained from the Lagrangian formalism as in classical field theory. An action functional is introduced as a space-time integral over a region of three-dimensional Euclidean space, of a Lagrangian density function of certain field variables. A Hamilton type extremum action principle is postulated with adequate boundary conditions, and a set of differential field equations is derived. With an appropriate Lagrangian density of the T-V type, the equation of motion for any viscous fluid is reproduced. A theorem referring to the invariance of the action under time variations lead to the generalized energy balance equation for the viscous fluid and to the energy balance equation proper. The same theoretical approach can be used to solve the problem of potential flow. (Author)

  15. A linear multiple balance method for discrete ordinates neutron transport equations

    International Nuclear Information System (INIS)

    Park, Chang Je; Cho, Nam Zin

    2000-01-01

    A linear multiple balance method (LMB) is developed to provide more accurate and positive solutions for the discrete ordinates neutron transport equations. In this multiple balance approach, one mesh cell is divided into two subcells with quadratic approximation of angular flux distribution. Four multiple balance equations are used to relate center angular flux with average angular flux by Simpson's rule. From the analysis of spatial truncation error, the accuracy of the linear multiple balance scheme is ο(Δ 4 ) whereas that of diamond differencing is ο(Δ 2 ). To accelerate the linear multiple balance method, we also describe a simplified additive angular dependent rebalance factor scheme which combines a modified boundary projection acceleration scheme and the angular dependent rebalance factor acceleration schme. It is demonstrated, via fourier analysis of a simple model problem as well as numerical calculations, that the additive angular dependent rebalance factor acceleration scheme is unconditionally stable with spectral radius < 0.2069c (c being the scattering ration). The numerical results tested so far on slab-geometry discrete ordinates transport problems show that the solution method of linear multiple balance is effective and sufficiently efficient

  16. The prediction of the cavitation phenomena including population balance modeling

    Science.gov (United States)

    Bannari, Rachid; Hliwa, Ghizlane Zineb; Bannari, Abdelfettah; Belghiti, Mly Taib

    2017-07-01

    Cavitation is the principal reason behind the behavior's modification of the hydraulic turbines. However, the experimental observations can not be appropriate to all cases due to the limitations in the measurement techniques. The mathematical models which have been implemented, use the mixture multiphase frame. As well as, most of the published work is limited by considering a constant bubble size distribution. However, this assumption is not realist. The aim of this article is the implementation and the use of a non-homogeneous multiphase model which solve two phases transport equation. The evolution of bubble size is considered by the population balance equation. This study is based on the eulerian-eulerian model, associated to the cavitation model. All the inter-phase forces such as drag, lift and virtual mass are used.

  17. A well-balanced scheme for Ten-Moment Gaussian closure equations with source term

    Science.gov (United States)

    Meena, Asha Kumari; Kumar, Harish

    2018-02-01

    In this article, we consider the Ten-Moment equations with source term, which occurs in many applications related to plasma flows. We present a well-balanced second-order finite volume scheme. The scheme is well-balanced for general equation of state, provided we can write the hydrostatic solution as a function of the space variables. This is achieved by combining hydrostatic reconstruction with contact preserving, consistent numerical flux, and appropriate source discretization. Several numerical experiments are presented to demonstrate the well-balanced property and resulting accuracy of the proposed scheme.

  18. Improved harmonic balance approach to periodic solutions of non-linear jerk equations

    International Nuclear Information System (INIS)

    Wu, B.S.; Lim, C.W.; Sun, W.P.

    2006-01-01

    An analytical approximate approach for determining periodic solutions of non-linear jerk equations involving third-order time-derivative is presented. This approach incorporates salient features of both Newton's method and the method of harmonic balance. By appropriately imposing the method of harmonic balance to the linearized equation, the approach requires only one or two iterations to predict very accurate analytical approximate solutions for a large range of initial velocity amplitude. One typical example is used to verify and illustrate the usefulness and effectiveness of the proposed approach

  19. Some Matrix Iterations for Computing Generalized Inverses and Balancing Chemical Equations

    Directory of Open Access Journals (Sweden)

    Farahnaz Soleimani

    2015-11-01

    Full Text Available An application of iterative methods for computing the Moore–Penrose inverse in balancing chemical equations is considered. With the aim to illustrate proposed algorithms, an improved high order hyper-power matrix iterative method for computing generalized inverses is introduced and applied. The improvements of the hyper-power iterative scheme are based on its proper factorization, as well as on the possibility to accelerate the iterations in the initial phase of the convergence. Although the effectiveness of our approach is confirmed on the basis of the theoretical point of view, some numerical comparisons in balancing chemical equations, as well as on randomly-generated matrices are furnished.

  20. Multigrid preconditioning of the generator two-phase mixture balance equations in the Genepi software

    International Nuclear Information System (INIS)

    Belliard, M.; Grandotto, M.

    2003-01-01

    In the framework of the two-phase fluid simulations of the steam generators of pressurized water nuclear reactors, we present in this paper a geometric version of a pseudo-Full MultiGrid (pseudo- FMG) Full Approximation Storage (FAS) preconditioning of balance equations in the GENEPI code. In our application, the 3D steady state flow is reached by a transient computation using a semi-implicit fractional step algorithm for the averaged two-phase mixture balance equations (mass, momentum and energy for the secondary flow). Our application, running on workstation clusters, is based on a CEA code-linker and the PVM package. The difficulties to apply the geometric FAS multigrid method to the momentum and mass balance equations are addressed. The use of a sequential pseudo-FMG FAS twogrid method for both energy and mass/momentum balance equations, using dynamic multigrid cycles, leads to perceptibly improvements in the computation convergences. An original parallel red-black pseudo-FMG FAS three-grid algorithm is presented too. The numerical tests (steam generator mockup simulations) underline the sizable increase in speed of convergence of the computations, essentially for the ones involving a large number of freedom degrees (about 100 thousand cells). The two-phase mixture balance equation residuals are quickly reduced: the reached speed-up stands between 2 and 3 following the number of grids. The effects on the convergence behavior of the numerical parameters are investigated

  1. Coupled energy-drift and force-balance equations for high-field hot-carrier transport

    International Nuclear Information System (INIS)

    Huang, Danhong; Alsing, P.M.; Apostolova, T.; Cardimona, D.A.

    2005-01-01

    Coupled energy-drift and force-balance equations that contain a frictional force for the center-of-mass motion of electrons are derived for hot-electron transport under a strong dc electric field. The frictional force is found to be related to the net rate of phonon emission, which takes away the momentum of a phonon from an electron during each phonon-emission event. The net rate of phonon emission is determined by the Boltzmann scattering equation, which depends on the distribution of electrons interacting with phonons. The work done by the frictional force is included into the energy-drift equation for the electron-relative scattering motion and is found to increase the thermal energy of the electrons. The importance of the hot-electron effect in the energy-drift term under a strong dc field is demonstrated in reducing the field-dependent drift velocity and mobility. The Doppler shift in the energy conservation of scattering electrons interacting with impurities and phonons is found to lead to an anisotropic distribution of electrons in the momentum space along the field direction. The importance of this anisotropic distribution is demonstrated through a comparison with the isotropic energy-balance equation, from which we find that defining a state-independent electron temperature becomes impossible. To the leading order, the energy-drift equation is linearized with a distribution function by expanding it into a Fokker-Planck-type equation, along with the expansions of both the force-balance equation and the Boltzmann scattering equation for hot phonons

  2. Balance of liquid-phase turbulence kinetic energy equation for bubble-train flow

    International Nuclear Information System (INIS)

    Ilic, Milica; Woerner, Martin; Cacuci, Dan Gabriel

    2004-01-01

    In this paper the investigation of bubble-induced turbulence using direct numerical simulation (DNS) of bubbly two-phase flow is reported. DNS computations are performed for a bubble-driven liquid motion induced by a regular train of ellipsoidal bubbles rising through an initially stagnant liquid within a plane vertical channel. DNS data are used to evaluate balance terms in the balance equation for the liquid phase turbulence kinetic energy. The evaluation comprises single-phase-like terms (diffusion, dissipation and production) as well as the interfacial term. Special emphasis is placed on the procedure for evaluation of interfacial quantities. Quantitative analysis of the balance equation for the liquid phase turbulence kinetic energy shows the importance of the interfacial term which is the only source term. The DNS results are further used to validate closure assumptions employed in modelling of the liquid phase turbulence kinetic energy transport in gas-liquid bubbly flows. In this context, the performance of respective closure relations in the transport equation for liquid turbulence kinetic energy within the two-phase k-ε and the two-phase k-l model is evaluated. (author)

  3. Plasma balance equations based on orbit theory

    International Nuclear Information System (INIS)

    Lehnert, B.

    1982-01-01

    A set of plasma balance equations is proposed which is based on orbit theory and the particle distribution function, to provide means for theoretical analysis of a number of finite Larmor radius (FLR) phenomena without use of the Vlasov equation. Several important FLR effects originate from the inhomogeneity of an electric field in the plasma. The exact solution of a simple case shows that this inhomogeneity introduces fundamental changes in the physics of the particle motion. Thus, the periodic Larmor motion (gyration) is shifted in frequency and becomes elliptically polarized. Further, the non-periodic guiding-centre drift obtains additional components, part of which are accelerated such as to make the drift orbits intersect the equipotential surfaces of a static electric field. An attempt is finally made to classify the FLR effects, also with the purpose of identifying phenomena which have so far not been investigated. (author)

  4. The Approach to Equilibrium: Detailed Balance and the Master Equation

    Science.gov (United States)

    Alexander, Millard H.; Hall, Gregory E.; Dagdigian, Paul J.

    2011-01-01

    The approach to the equilibrium (Boltzmann) distribution of populations of internal states of a molecule is governed by inelastic collisions in the gas phase and with surfaces. The set of differential equations governing the time evolution of the internal state populations is commonly called the master equation. An analytic solution to the master…

  5. Analytical solution of population balance equation involving ...

    Indian Academy of Sciences (India)

    This paper presents an effective analytical simulation to solve population .... considering spatial dependence and growth, based on the so-called LPA formulation as .... But the particle size distribution is defined so that n(v,t) dx is the number of ..... that was made beforehand in the construction of the analytical solutions ...

  6. A moment projection method for population balance dynamics with a shrinkage term

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Shaohua [Department of Mechanical Engineering, National University of Singapore, Engineering Block EA, Engineering Drive 1, 117576 (Singapore); Yapp, Edward K.Y.; Akroyd, Jethro; Mosbach, Sebastian [Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge, CB2 3RA (United Kingdom); Xu, Rong [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 (Singapore); Yang, Wenming [Department of Mechanical Engineering, National University of Singapore, Engineering Block EA, Engineering Drive 1, 117576 (Singapore); Kraft, Markus, E-mail: mk306@cam.ac.uk [Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge, CB2 3RA (United Kingdom); School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 (Singapore)

    2017-02-01

    A new method of moments for solving the population balance equation is developed and presented. The moment projection method (MPM) is numerically simple and easy to implement and attempts to address the challenge of particle shrinkage due to processes such as oxidation, evaporation or dissolution. It directly solves the moment transport equation for the moments and tracks the number of the smallest particles using the algorithm by Blumstein and Wheeler (1973) . The performance of the new method is measured against the method of moments (MOM) and the hybrid method of moments (HMOM). The results suggest that MPM performs much better than MOM and HMOM where shrinkage is dominant. The new method predicts mean quantities which are almost as accurate as a high-precision stochastic method calculated using the established direct simulation algorithm (DSA).

  7. Development and linearization of generalized material balance equation for coal bed methane reservoirs

    International Nuclear Information System (INIS)

    Penuela, G; Ordonez R, A; Bejarano, A

    1998-01-01

    A generalized material balance equation was presented at the Escuela de Petroleos de la Universidad Industrial de Santander for coal seam gas reservoirs based on Walsh's method, who worked in an analogous approach for oil and gas conventional reservoirs (Walsh, 1995). Our equation was based on twelve similar assumptions itemized by Walsh for his generalized expression for conventional reservoirs it was started from the same volume balance consideration and was finally reorganized like Walsh (1994) did. Because it is not expressed in terms of traditional (P/Z) plots, as proposed by King (1990), it allows to perform a lot of quantitative and qualitative analyses. It was also demonstrated that the existent equations are only particular cases of the generalized expression evaluated under certain restrictions. This equation is applicable to coal seam gas reservoirs in saturated, equilibrium and under saturated conditions, and to any type of coal beds without restriction on especial values of the constant diffusion

  8. Well-balanced schemes for the Euler equations with gravitation: Conservative formulation using global fluxes

    Science.gov (United States)

    Chertock, Alina; Cui, Shumo; Kurganov, Alexander; Özcan, Şeyma Nur; Tadmor, Eitan

    2018-04-01

    We develop a second-order well-balanced central-upwind scheme for the compressible Euler equations with gravitational source term. Here, we advocate a new paradigm based on a purely conservative reformulation of the equations using global fluxes. The proposed scheme is capable of exactly preserving steady-state solutions expressed in terms of a nonlocal equilibrium variable. A crucial step in the construction of the second-order scheme is a well-balanced piecewise linear reconstruction of equilibrium variables combined with a well-balanced central-upwind evolution in time, which is adapted to reduce the amount of numerical viscosity when the flow is at (near) steady-state regime. We show the performance of our newly developed central-upwind scheme and demonstrate importance of perfect balance between the fluxes and gravitational forces in a series of one- and two-dimensional examples.

  9. On the balance equations for a dilute binary mixture in special relativity

    International Nuclear Information System (INIS)

    Moratto, Valdemar; Garcia-Perciante, A. L.; Garcia-Colin, L. S.

    2010-01-01

    In this work we study the properties of a relativistic mixture of two non-reacting species in thermal local equilibrium. We use the full Boltzmann equation (BE) to find the general balance equations. Following conventional ideas in kinetic theory, we use the concept of chaotic velocity. This is a novel approach to the problem. The resulting equations will be the starting point of the calculation exhibiting the correct thermodynamic forces and the corresponding fluxes; these results will be published elsewhere.

  10. Detailed balance principle and finite-difference stochastic equation in a field theory

    International Nuclear Information System (INIS)

    Kozhamkulov, T.A.

    1986-01-01

    A finite-difference equation, which is a generalization of the Langevin equation in field theory, has been obtained basing upon the principle of detailed balance for the Markov chain. Advantages of the present approach as compared with the conventional Parisi-Wu method are shown for examples of an exactly solvable problem of zero-dimensional quantum theory and a simple numerical simulation

  11. Balanced Central Schemes for the Shallow Water Equations on Unstructured Grids

    Science.gov (United States)

    Bryson, Steve; Levy, Doron

    2004-01-01

    We present a two-dimensional, well-balanced, central-upwind scheme for approximating solutions of the shallow water equations in the presence of a stationary bottom topography on triangular meshes. Our starting point is the recent central scheme of Kurganov and Petrova (KP) for approximating solutions of conservation laws on triangular meshes. In order to extend this scheme from systems of conservation laws to systems of balance laws one has to find an appropriate discretization of the source terms. We first show that for general triangulations there is no discretization of the source terms that corresponds to a well-balanced form of the KP scheme. We then derive a new variant of a central scheme that can be balanced on triangular meshes. We note in passing that it is straightforward to extend the KP scheme to general unstructured conformal meshes. This extension allows us to recover our previous well-balanced scheme on Cartesian grids. We conclude with several simulations, verifying the second-order accuracy of our scheme as well as its well-balanced properties.

  12. Principle of detailed balance and the finite-difference stochastic equation in field theory

    International Nuclear Information System (INIS)

    Kozhamkulov, T.A.

    1986-01-01

    The principle of detailed balance for the Markov chain is used to obtain a finite-difference equation which generalizes the Langevin equation in field theory. The advantages of using this approach compared to the conventional Parisi-Wu method are demonstrated for the examples of an exactly solvable problem in zero-dimensional quantum theory and a simple numerical simulation

  13. On the relation between the fundamental equation of thermodynamics and the energy balance equation in the context of closed and open systems

    NARCIS (Netherlands)

    Knuiman, J.T.; Barneveld, P.A.

    2012-01-01

    In this paper, we elaborate on the connection between the fundamental equation of thermodynamics, which is essentially the combination of the First and Second Laws of thermodynamics, and the energy balance equation in the context of closed and open systems. We point out some misinterpretations in

  14. Discrete population balance models of random agglomeration and cleavage in polymer pyrolysis

    Directory of Open Access Journals (Sweden)

    John E. J. Staggs

    2017-05-01

    Full Text Available The processes of random agglomeration and cleavage (both of which are important for the development of new models of polymer combustion, but are also applicable in a wide range of fields including atmospheric physics, radiation modelling and astrophysics are analysed using population balance methods. The evolution of a discrete distribution of particles is considered within this framework, resulting in a set of ordinary differential equations for the individual particle concentrations. Exact solutions for these equations are derived, together with moment generating functions. Application of the discrete Laplace transform (analogous to the Z-transform is found to be effective in these problems, providing both exact solutions for particle concentrations and moment generating functions. The combined agglomeration-cleavage problem is also considered. Unfortunately, it has been impossible to find an exact solution for the full problem, but a stable steady state has been identified and computed.

  15. Transport methods: general. 3. An Additive Angular-Dependent Re-balance Acceleration Method for Neutron Transport Equations

    International Nuclear Information System (INIS)

    Cho, Nam Zin; Park, Chang Je

    2001-01-01

    An additive angular-dependent re-balance (AADR) factor acceleration method is described to accelerate the source iteration of discrete ordinates transport calculation. The formulation of the AADR method follows that of the angular-dependent re-balance (ADR) method in that the re-balance factor is defined only on the cell interface and in that the low-order equation is derived by integrating the transport equation (high-order equation) over angular subspaces. But, the re-balance factor is applied additively. While the AADR method is similar to the boundary projection acceleration and the alpha-weighted linear acceleration, it is more general and does have distinct features. The method is easily extendible to DP N and low-order S N re-balancing, and it does not require consistent discretizations between the high- and low-order equations as in diffusion synthetic acceleration. We find by Fourier analysis and numerical results that the AADR method with a chosen form of weighting functions is unconditionally stable and very effective. There also exists an optimal weighting parameter that leads to the smallest spectral radius. The AADR acceleration method described in this paper is simple to implement, unconditionally stable, and very effective. It uses a physically based weighting function with an optimal parameter, leading to the best spectral radius of ρ<0.1865, compared to ρ<0.2247 of DSA. The application of the AADR acceleration method with the LMB scheme on a test problem shows encouraging results

  16. Reduction of a single granule drying model: An essential step in preparation of a population balance model with a continuous growth term

    DEFF Research Database (Denmark)

    Mortier, Séverine Thérèse F.C.; Daele, Timothy, Van; Gernaey, Krist V.

    2013-01-01

    in the reduced model. Simulations of the complex drying model were, in a next phase, used to develop the reduced model, which describes the decrease of the moisture content in function of the gas temperature. The developed reduced model was then included in a Population Balance Equation (PBE) to describe......The development of a Population Balance Model (PBM) for a pharmaceutical granule drying process requires a continuous growth term; the latter actually represents the drying process as the moisture content is the internal coordinate of the PBM. To establish such a PBM, a complex drying model...

  17. Force-balance and differential equation for the ground-state electron density in atoms and molecules

    International Nuclear Information System (INIS)

    Amovilli, C.; March, N.H.; Gal, T.; Nagy, A.

    2000-01-01

    Holas and March (1995) established a force-balance equation from the many-electron Schroedinger equation. Here, the authors propose this as a basis for the construction of a (usually approximate) differential equation for the ground-state electron density. By way of example they present the simple case of two-electron systems with different external potentials but with weak electron-electron Coulomb repulsion λe 2 /r 12 . In this case first-order Rayleigh-Schroedinger (RS) perturbation theory of the ground-state wave function is known to lead to a compact expression for the first-order density matrix γ(r,rprime) in terms of its diagonal density ρ(r) and the density corresponding to λ = 0. This result allows the force-balance equation to be written as a third-order linear, differential homogeneous equation for the ground-state electron density ρ(r). The example of the two-electron Hookean atom is treated: For this case one can also transcend the first-order RS perturbation theory and get exact results for discrete choices of force constants (external potential)

  18. Linear representation of algebras with non-associative operations which are satisfy in the balanced functional equations

    International Nuclear Information System (INIS)

    Ehsani, Amir

    2015-01-01

    Algebras with a pair of non-associative binary operations (f, g) which are satisfy in the balanced quadratic functional equations with four object variables considered. First, we obtain a linear representation for the operations, of this kind of binary algebras (A,f,g), over an abelian group (A, +) and then we generalize the linear representation of operations, to an algebra (A,F) with non-associative binary operations which are satisfy in the balanced quadratic functional equations with four object variables. (paper)

  19. Balancing redox equations: reaction of Cr(III) and chlorate in basic solution.

    OpenAIRE

    Milla González, Miguel

    2011-01-01

    This file is an interactive exercise on balancing of redox reactions. The redox system consists of the Cr(III) oxidation by means of the action of chlorate anion in basic solution. In these circumstances, Cr(III) exists as the Cr(OH)3 green precipitate. After finding out the oxidation states of the species involved, the user must write the equations of the half-reactions for both processes. A counter of atoms and charges makes this task easy and four possible ways of balancing are possible...

  20. The use of material balanced equation to determine the oil water ...

    African Journals Online (AJOL)

    The oil water contact of an oil reservoir can be determined using some geophysical well logs. However, some of the methods might not be accurate. Therefore the material balanced equation which is an accurate means of formation evaluation is critically analysed in this study and then used to determine the oil water contact ...

  1. Hyperbolic partial differential equations populations, reactors, tides and waves theory and applications

    CERN Document Server

    Witten, Matthew

    1983-01-01

    Hyperbolic Partial Differential Equations, Volume 1: Population, Reactors, Tides and Waves: Theory and Applications covers three general areas of hyperbolic partial differential equation applications. These areas include problems related to the McKendrick/Von Foerster population equations, other hyperbolic form equations, and the numerical solution.This text is composed of 15 chapters and begins with surveys of age specific population interactions, populations models of diffusion, nonlinear age dependent population growth with harvesting, local and global stability for the nonlinear renewal eq

  2. Students' Understanding of Conservation of Matter, Stoichiometry and Balancing Equations in Indonesia

    Science.gov (United States)

    Agung, Salamah; Schwartz, Marc S.

    2007-01-01

    This study examines Indonesian students' understanding of conservation of matter, balancing of equations and stoichiometry. Eight hundred and sixty-seven Grade 12 students from 22 schools across four different cities in two developed provinces in Indonesia participated in the study. Nineteen teachers also participated in order to validate the…

  3. Numerical study of a stochastic particle algorithm solving a multidimensional population balance model for high shear granulation

    International Nuclear Information System (INIS)

    Braumann, Andreas; Kraft, Markus; Wagner, Wolfgang

    2010-01-01

    This paper is concerned with computational aspects of a multidimensional population balance model of a wet granulation process. Wet granulation is a manufacturing method to form composite particles, granules, from small particles and binders. A detailed numerical study of a stochastic particle algorithm for the solution of a five-dimensional population balance model for wet granulation is presented. Each particle consists of two types of solids (containing pores) and of external and internal liquid (located in the pores). Several transformations of particles are considered, including coalescence, compaction and breakage. A convergence study is performed with respect to the parameter that determines the number of numerical particles. Averaged properties of the system are computed. In addition, the ensemble is subdivided into practically relevant size classes and analysed with respect to the amount of mass and the particle porosity in each class. These results illustrate the importance of the multidimensional approach. Finally, the kinetic equation corresponding to the stochastic model is discussed.

  4. A STRUCTURAL EQUATION MODEL-II FOR WORK-LIFE BALANCE OF IT PROFESSIONALS IN CHENNAI

    OpenAIRE

    Rashida A. Banu

    2016-01-01

    The study developed and tested a model of work life balance of IT professionals employing structural equation modeling (SEM) to analyze the relationship between work place support (WPS) and work interference with personal life (WIPL), personal life interference with work (PLIW), satisfaction with work-life balance (SWLB) and improved effectiveness at work (IEW). The model fit the data well and hypotheses are generally supported. WPS and SWLB are negatively related to WIPL and P...

  5. Constitutive equations for energy balance evaluation in metals under inelastic deformation

    Science.gov (United States)

    Kostina, A.; Plekhov, O.; Venkatraman, B.

    2017-12-01

    The work is devoted to the development of constitutive equations for energy balance evaluation in plastically deformed metals. The evolution of the defect system is described by a previously obtained model based on the Boltzmann-Gibbs statistics. In the framework of this model, a collective behavior of mesodefect ensembles is taken into account by the introduction of an internal variable representing additional structural strain. This parameter enables the partition of plastic work into dissipated heat and stored energy. The proposed model is applied to energy balance calculation in a Ti-1Al-1Mn specimen subjected to cyclic loading. Simulation results have shown that the model is able to describe an upward trend in the stored energy value with the increase in the load ratio.

  6. Reduction of structured population models to threshold-type delay equations and functional differential equations: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Smith, H.L. (Arizona State Univ., Tempe (United States))

    1993-01-01

    It is shown by way of a simple example that certain structured population models lead naturally to differential delay equations of the threshold type and that these equations can be transformed in a natural way to functional differential equations. The model examined can be viewed as a model of competition between adults and juveniles of a single population. The results indicate the possibility that this competition leads to instability. 28 refs., 2 figs.

  7. T-Stability of the Heun Method and Balanced Method for Solving Stochastic Differential Delay Equations

    Directory of Open Access Journals (Sweden)

    Xiaolin Zhu

    2014-01-01

    Full Text Available This paper studies the T-stability of the Heun method and balanced method for solving stochastic differential delay equations (SDDEs. Two T-stable conditions of the Heun method are obtained for two kinds of linear SDDEs. Moreover, two conditions under which the balanced method is T-stable are obtained for two kinds of linear SDDEs. Some numerical examples verify the theoretical results proposed.

  8. Some Matrix Iterations for Computing Generalized Inverses and Balancing Chemical Equations

    OpenAIRE

    Soleimani, Farahnaz; Stanimirovi´c, Predrag; Soleymani, Fazlollah

    2015-01-01

    An application of iterative methods for computing the Moore–Penrose inverse in balancing chemical equations is considered. With the aim to illustrate proposed algorithms, an improved high order hyper-power matrix iterative method for computing generalized inverses is introduced and applied. The improvements of the hyper-power iterative scheme are based on its proper factorization, as well as on the possibility to accelerate the iterations in the initial phase of the convergence. Although the ...

  9. A STRUCTURAL EQUATION MODEL-II FOR WORK-LIFE BALANCE OF IT PROFESSIONALS IN CHENNAI

    Directory of Open Access Journals (Sweden)

    Rashida A. Banu

    2016-05-01

    Full Text Available The study developed and tested a model of work life balance of IT professionals employing structural equation modeling (SEM to analyze the relationship between work place support (WPS and work interference with personal life (WIPL, personal life interference with work (PLIW, satisfaction with work-life balance (SWLB and improved effectiveness at work (IEW. The model fit the data well and hypotheses are generally supported. WPS and SWLB are negatively related to WIPL and PLIW. However, there is a positive relationship between SWLB and IEW.

  10. Structural Observability and Sensor Node Selection for Complex Networks Governed by Nonlinear Balance Equations

    NARCIS (Netherlands)

    Kawano, Yu; Cao, Ming

    2017-01-01

    We define and then study the structural observability for a class of complex networks whose dynamics are governed by the nonlinear balance equations. Although related notions of observability of such complex networks have been studied before and in particular, necessary conditions have been reported

  11. Can we close the long term mass balance equation for pollutants in highway ponds?

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2007-01-01

    The paper discusses the prospects of finding the long term mass balance on basis of short term simulations. A step in this process is to see to which degree the mass balance equation can be closed by measurements. Accordingly the total accumulation of heavy metals and PAH's in 8 Danish detention...... ponds only receiving runoff from highways have been measured. The result shows that the incoming mass of heavy metals from short term runoff events is accumulated. This is not observable in the same magnitude for the toxic organic compounds. The results also show that the accumulation rates...

  12. Analysis of single hyphal growth and fragmentation in submerged cultures using a population model

    DEFF Research Database (Denmark)

    Krabben, Preben; Nielsen, Søren; Michelsen, Michael Locht

    1997-01-01

    Descriptions of population dynamics in submerged cultures are important when studying the mechanisms of growth and fragmentation of filamentous microorganisms. Population models are traditionally formulated as population balance equations. Population models of filamentous morphology are difficult...... to solve because of random fragmentation, which introduces an integral term into the population balance equations. Balances for the systemic properties, e.g. concentration of hyphal elements, substrate concentration, average total hyphal length, and average number of growing tips, are set up. Based...... on these balances one can solve the inverse problem, i.e. determination of kinetic parameters directly from measurements of the hyphal morphology. Both a Monte Carlo method and a discretization method have been used to calculate the steady-state population distribution. The two methods are compared and the Monte...

  13. Particle and parallel momentum balance equations with inclusion of drifts, for modelling strong- to weakly-collisional edge plasmas

    International Nuclear Information System (INIS)

    Chankin, A. V.; Stangeby, P. C.

    2006-01-01

    A system of plasma particle and parallel momentum balance equations is derived appropriate for understanding the role of drifts in the edge and for edge modelling, particularly in the scrape-off layer (SOL) of tokamaks, stellarators and other magnetic confinement devices. The formulation allows for strong collisionality-but also covers the case of weak collisionality and strong drifts, a combination often encountered in the SOL. The most important terms are identified by assessing the magnitude of characteristic velocities and fluxes for the plasma edge region. Explanations of the physical nature of each term are provided. A number of terms that are sometimes not included in edge modelling has been included in the parallel momentum balance equation after detailed analysis of the parallel component of the gradient of the total pressure-stress tensor. This includes terms related to curvature and divergence of the field lines, as well as further contributions coming from viscous forces related mainly to the ion centrifugal drift. All these terms are shown to be roughly of the same order of magnitude as convective momentum fluxes related to drifts and therefore should be included in the momentum balance equation

  14. Generalised and Fractional Langevin Equations-Implications for Energy Balance Models

    Science.gov (United States)

    Watkins, N. W.; Chapman, S. C.; Chechkin, A.; Ford, I.; Klages, R.; Stainforth, D. A.

    2017-12-01

    Energy Balance Models (EBMs) have a long heritage in climate science, including their use in modelling anomalies in global mean temperature. Many types of EBM have now been studied, and this presentation concerns the stochastic EBMs, which allow direct treatment of climate fluctuations and noise. Some recent stochastic EBMs (e.g. [1]) map on to Langevin's original form of his equation, with temperature anomaly replacing velocity, and other corresponding replacements being made. Considerable sophistication has now been reached in the application of multivariate stochastic Langevin modelling in many areas of climate. Our work is complementary in intent and investigates the Mori-Kubo "Generalised Langevin Equation" (GLE) which incorporates non-Markovian noise and response in a univariate framework, as a tool for modelling GMT [2]. We show how, if it is present, long memory simplifies the GLE to a fractional Langevin equation (FLE). Evidence for long range memory in global temperature, and the success of fractional Gaussian noise in its prediction [5] has already motivated investigation of a power law response model [3,4,5]. We go beyond this work to ask whether an EBM of FLE-type exists, and what its solutions would be. [l] Padilla et al, J. Climate (2011); [2] Watkins, GRL (2013); [3] Rypdal, JGR (2012); [4] Rypdal and Rypdal, J. Climate (2014); [5] Lovejoy et al, ESDD (2015).

  15. Lineage dynamics and mutation-selection balance in non-adapting asexual populations

    Science.gov (United States)

    Pénisson, Sophie; Sniegowski, Paul D.; Colato, Alexandre; Gerrish, Philip J.

    2013-02-01

    In classical population genetics, mutation-selection balance refers to the equilibrium frequency of a deleterious allele established and maintained under two opposing forces: recurrent mutation, which tends to increase the frequency of the allele; and selection, which tends to decrease its frequency. In a haploid population, if μ denotes the per capita rate of production of the deleterious allele by mutation and s denotes the selective disadvantage of carrying the allele, then the classical mutation-selection balance frequency of the allele is approximated by μ/s. This calculation assumes that lineages carrying the mutant allele in question—the ‘focal allele’—do not accumulate deleterious mutations linked to the focal allele. In principle, indirect selection against the focal allele caused by such additional mutations can decrease the frequency of the focal allele below the classical mutation-selection balance. This effect of indirect selection will be strongest in an asexual population, in which the entire genome is in linkage. Here, we use an approach based on a multitype branching process to investigate this effect, analyzing lineage dynamics under mutation, direct selection, and indirect selection in a non-adapting asexual population. We find that the equilibrium balance between recurrent mutation to the focal allele and the forces of direct and indirect selection against the focal allele is closely approximated by γμ/(s + U) (s = 0 if the focal allele is neutral), where γ ≈ eθθ-(ω+θ)(ω + θ)(Γ(ω + θ) - Γ(ω + θ,θ)), \\theta =U/\\tilde {s}, and \\omega =s/\\tilde {s}; U denotes the genomic deleterious mutation rate and \\tilde {s} denotes the geometric mean selective disadvantage of deleterious mutations elsewhere on the genome. This mutation-selection balance for asexual populations can remain surprisingly invariant over wide ranges of the mutation rate.

  16. Understanding the interrelationship between the synthesis of urea and gluconeogenesis by formulating an overall balanced equation.

    Science.gov (United States)

    Ipata, Piero L; Pesi, Rossana

    2017-06-01

    It is well known that a strong metabolic interrelationship exists between ureagenesis and gluconeogenesis. In this paper, we present a detailed, overall equation, describing a possible metabolic link between ureagenesis and gluconeogenesis. We adopted a guided approach in which we strongly suggest that students, when faced with the problem of obtaining the overall equation of a metabolic pathway, carefully account for all atoms and charges of the single reactions, as well as the cellular localizations of the substrates, and the related transport systems. If this suggestion is always taken into account, a balanced, overall equation of a metabolic pathway will be obtained, which strongly facilitates the discussion of its physiological role. Unfortunately, textbooks often report unbalanced overall equations of metabolic pathways, including ureagenesis and gluconeogenesis. Most likely the reason is that metabolism and enzymology have been neglected for about three decades, owing to the remarkable advances of molecular biology and molecular genetics. In this paper, we strongly suggest that students, when faced with the problem of obtaining the overall reaction of a metabolic pathway, carefully control if the single reactions are properly balanced for atoms and charges. Following this suggestion, we were able to obtain an overall equation describing the metabolic interrelationship between ureagenesis and gluconeogenesis, in which urea and glucose are the final products. The aim is to better rationalize this topic and to convince students and teachers that metabolism is an important and rewarding chapter of human physiology. Copyright © 2017 the American Physiological Society.

  17. Prediction equation of resting energy expenditure in an adult Spanish population of obese adult population.

    Science.gov (United States)

    de Luis, D A; Aller, R; Izaola, O; Romero, E

    2006-01-01

    The aim of our study was to evaluate the accuracy of the equations to estimate REE in obese patents and develop a new equation in our obese population. A population of 200 obesity outpatients was analyzed in a prospective way. The following variables were specifically recorded: age, weight, body mass index (BMI), waist circumference, and waist-to-hip ratio. Basal glucose, insulin, and TSH (thyroid-stimulating hormone) were measured. An indirect calorimetry and a tetrapolar electrical bioimpedance were performed. REE measured by indirect calorimetry was compared with REE obtained by prediction equations to obese or nonobese patients. The mean age was 44.8 +/- 16.81 years and the mean BMI 34.4 +/- 5.3. Indirect calorimetry showed that, as compared to women, men had higher resting energy expenditure (REE) (1,998.1 +/- 432 vs. 1,663.9 +/- 349 kcal/day; p consumption (284.6 +/- 67.7 vs. 238.6 +/- 54.3 ml/min; p predicted by prediction equations showed the next data; Berstein's equation (r = 0.65; p prediction equation was REE = 58.6 + (6.1 x weight (kg)) + (1,023.7 x height (m)) - (9.5 x age). The female model was REE = 1,272.5 + (9.8 x weight (kg)) - (61.6 x height (m)) - (8.2 x age). Our prediction equations showed a nonsignificant difference with REE measured (-3.7 kcal/day) with a significant correlation coefficient (r = 0.67; p prediction equations overestimated and underestimated REE measured. WHO equation developed in normal weight individuals provided the closest values. The two new equations (male and female equations) developed in our study had a good accuracy. Copyright 2006 S. Karger AG, Basel.

  18. Spirometry reference equations for central European populations from school age to old age.

    Science.gov (United States)

    Rochat, Mascha K; Laubender, Ruediger P; Kuster, Daniela; Braendli, Otto; Moeller, Alexander; Mansmann, Ulrich; von Mutius, Erika; Wildhaber, Johannes

    2013-01-01

    Spirometry reference values are important for the interpretation of spirometry results. Reference values should be updated regularly, derived from a population as similar to the population for which they are to be used and span across all ages. Such spirometry reference equations are currently lacking for central European populations. To develop spirometry reference equations for central European populations between 8 and 90 years of age. We used data collected between January 1993 and December 2010 from a central European population. The data was modelled using "Generalized Additive Models for Location, Scale and Shape" (GAMLSS). The spirometry reference equations were derived from 118'891 individuals consisting of 60'624 (51%) females and 58'267 (49%) males. Altogether, there were 18'211 (15.3%) children under the age of 18 years. We developed spirometry reference equations for a central European population between 8 and 90 years of age that can be implemented in a wide range of clinical settings.

  19. Spirometry reference equations for central European populations from school age to old age.

    Directory of Open Access Journals (Sweden)

    Mascha K Rochat

    Full Text Available BACKGROUND: Spirometry reference values are important for the interpretation of spirometry results. Reference values should be updated regularly, derived from a population as similar to the population for which they are to be used and span across all ages. Such spirometry reference equations are currently lacking for central European populations. OBJECTIVE: To develop spirometry reference equations for central European populations between 8 and 90 years of age. MATERIALS: We used data collected between January 1993 and December 2010 from a central European population. The data was modelled using "Generalized Additive Models for Location, Scale and Shape" (GAMLSS. RESULTS: The spirometry reference equations were derived from 118'891 individuals consisting of 60'624 (51% females and 58'267 (49% males. Altogether, there were 18'211 (15.3% children under the age of 18 years. CONCLUSION: We developed spirometry reference equations for a central European population between 8 and 90 years of age that can be implemented in a wide range of clinical settings.

  20. Work-life balance culture, work-home interaction, and emotional exhaustion: a structural equation modeling approach.

    Science.gov (United States)

    Nitzsche, Anika; Pfaff, Holger; Jung, Julia; Driller, Elke

    2013-01-01

    To examine the relationships among employees' emotional exhaustion, positive and negative work-home interaction, and perceived work-life balance culture in companies. Data for this study were collected through online surveys of employees from companies in the micro- and nanotechnology sectors (N = 509). A structural equation modeling analysis was performed. A company culture perceived by employees as supportive of their work-life balance was found to have both a direct negative effect on emotional exhaustion and an indirect negative effect meditated by negative work-home interaction. In addition, whereas negative work-home interaction associated positively with emotional exhaustion, positive work-home interaction had no significant effect. The direct and indirect relationship between work-life balance culture and emotional exhaustion has practical implications for health promotion in companies.

  1. Energy balance in tearing modes

    International Nuclear Information System (INIS)

    Wesson, J.A.

    1993-01-01

    The energy balance in tearing modes is described in terms of exact separate energy balance equations. Each of these equations describes identified physical processes, and their sum gives the conservation of total energy. One of the energy balance equations corresponds to Furth's description. (Author)

  2. Steady state solution of the Fokker-Planck equation combined with unidirectional quasilinear diffusion under detailed balance conditions

    International Nuclear Information System (INIS)

    Hizanidis, K.

    1984-04-01

    The relativistic collisional Fokker-Planck equation combined with an externally imposed unidirectional quasilinear (rf) diffusion is solved for arbitrary values of rf diffusion coefficient under conditions of detailed balance of the staionary joint distribution involved. The detailed balance condition imposes a restriction on the functional form of the quasilinear diffusion coefficient which might be associated with the existence of a saturated spectrum of fluctuation in a quasilinearly rf-driven plasma

  3. Modeling real-time balancing power demands in wind power systems using stochastic differential equations

    International Nuclear Information System (INIS)

    Olsson, Magnus; Perninge, Magnus; Soeder, Lennart

    2010-01-01

    The inclusion of wind power into power systems has a significant impact on the demand for real-time balancing power due to the stochastic nature of wind power production. The overall aim of this paper is to present probabilistic models of the impact of large-scale integration of wind power on the continuous demand in MW for real-time balancing power. This is important not only for system operators, but also for producers and consumers since they in most systems through various market solutions provide balancing power. Since there can occur situations where the wind power variations cancel out other types of deviations in the system, models on an hourly basis are not sufficient. Therefore the developed model is in continuous time and is based on stochastic differential equations (SDE). The model can be used within an analytical framework or in Monte Carlo simulations. (author)

  4. Bioelectrical impedance analysis (BIA) equations validation against hydrodensitometry in a Colombian population

    International Nuclear Information System (INIS)

    Caicedo-Eraso, J C; Gonzalez-Correa, C A; Gonzalez-Correa, C H

    2013-01-01

    Several studies have shown that the accuracy of BIA results depends of ethnicity, age, gender, hormonal and genetic variations and, so far, there are not specific equations for Colombian population. The purpose was to evaluate reported BIA equations to determine their usefulness in body composition assessment in young females from Colombia using hydrodensitometry as the reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, multi-frequency BIA, residual lung volume (RV) and underwater weight (UWW) were measured. Five BIA equations met the inclusion criteria of this study. Three equations overestimated and two equations underestimated body fat (BF). Paired Student t-test and Bland and Altman analysis (p<0.05) showed significant differences in four BIA equations. However, all standard error of estimate (SEE) to BF was greater than 2.7 kg. This study showed that the five selected BIA equations are not valid for estimation of body composition in young females from Colombia. It is recommended to develop BIA equations to improve BF fat assessment in our population.

  5. A new complex vector method for balancing chemical equations: Nova kompleksna metoda za uravnoteženje kemičnih enačb:

    OpenAIRE

    Risteski, Ice B.

    2010-01-01

    In this article, the author discovers a paradox of balancing chemical equations. The many counterexamples illustrate that the considered procedure of balancing chemical equations given in the paper1 is inconsistent. A new complex vector method for paradox resolution is given too. V članku avtor opisuje paradoks pri uravnoteženju kemijskih reakcij. Več primerov dokazuje, da je procedura uravnoteženja kemijskih reakcij v viru1 inkonsistentna. Predstavljena je nova kompleksna vektorska metoda...

  6. New diffusion-sythetic acceleration methods for the SN equations with corner balance spatial differencing

    International Nuclear Information System (INIS)

    Wareing, T.A.

    1993-01-01

    New methods are presented for diffusion-synthetic accelerating the S N equations in slab and x-y geometries with the corner balance spatial differencing scheme. With the standard diffusion-synthetic acceleration method, the discretized diffusion problem is derived from the discretized S N problem to insure stability through consistent differencing. The major difference between our new methods and standard diffusion-synthetic acceleration is that the discretized diffusion problem is derived from a discretization of the P 1 equations, independently of the discretized S N problem. We present theoretical and numerical results to show that these new methods are unconditionally efficient in slab and x-y geometries with rectangular spatial meshes and isotropic scattering. (orig.)

  7. A performance measurement using balanced scorecard and structural equation modeling

    Directory of Open Access Journals (Sweden)

    Rosha Makvandi

    2014-02-01

    Full Text Available During the past few years, balanced scorecard (BSC has been widely used as a promising method for performance measurement. BSC studies organizations in terms of four perspectives including customer, internal processes, learning and growth and financial figures. This paper presents a hybrid of BSC and structural equation modeling (SEM to measure the performance of an Iranian university in province of Alborz, Iran. The proposed study of this paper uses this conceptual method, designs a questionnaire and distributes it among some university students and professors. Using SEM technique, the survey analyzes the data and the results indicate that the university did poorly in terms of all four perspectives. The survey extracts necessary target improvement by presenting necessary attributes for performance improvement.

  8. Particular cases of materials balance equation generalized for gas deposits associated to the coal

    International Nuclear Information System (INIS)

    Penuela, G; Ordonez, A; Bejarano, A

    1997-01-01

    One of the fundamental principles used in the work, developed in engineering is the law of the matter conservation. The application of this principle to the hydrocarbons fields, with the purpose of to quantify and to be predicted expresses by means of materials balance method. While the equation construction of conventional materials balance and the calculations that come with their application are not a difficult task, the approach of selection of the solution that better it represents the deposit it is one of the problems that the petroleum engineer should face. The materials balance is a useful analysis method of the deposit operation, reserves estimate of raw and gas, and prediction of the future behavior of the deposit. The coal, beds, devonian shales and geo pressurized-aquifer are some examples of natural gas sources and to possess production mechanisms and behaviors significantly different to the traditional than have been considered as non conventional deposits

  9. Mass-Inertial Characteristics and Dimensionless Equations of Two-bearing Rotor Motion with Auto-balancer in Terms of Compensating Body Mass

    Directory of Open Access Journals (Sweden)

    A. N. Gorbenko

    2015-01-01

    Full Text Available Modern rotary machines use auto-balancing devices of passive type to provide automatic balancing of rotors and reduce vibration. Most available researches on the rotor auto-balancing dynamics and stability are based on the assumption that the compensating bodies of the autobalancer, as well as the rotor imbalance, are infinitesimal values. The literature review has shown that the problems concerning the automatic balancing of rotor with its three-dimensional motion are solved approximately and require an in-depth analysis taking into consideration the final mass of the compensating bodies.The paper analyses the effect of an auto-balancer mass on the mass-inertial properties of the three-dimensional rotor motion. It gives the autonomous equations of the system motion. The work shows that attaching the point masses of compensating auto-balancer bodies and imbalance to the rotor causes an increase, however non-identical, in all components of the total inertia tensor of the mechanical system. This leads to a qualitative change in mass-inertial characteristics of the system.The composite rotor becomes an inertia anisotropic body in which the inertia moments about the two transverse own axes are not equal to each other. The rotor anisotropy results in complicated dynamic behavior of the gyroscopic rotor. In this case, the additional critical rotor speeds and the zones of instability of motion may occur.It is shown that in the case of using multi-body auto-balancer the inertial parameters of the rotor system grow into the interval values, i.e. their values are not uniquely determined and may be equal to a variety values from a certain range. Thus, the degree of inertial anisotropy and other auto-balancing parameters are the interval values as well in this case.The system of dimensionless equations of rotary machine motion, which contains the minimum required number of dimensionless parameters, has been obtained. The specific ranges of the dimensionless

  10. BREIT code: Analytical solution of the balance rate equations for charge-state evolutions of heavy-ion beams in matter

    Energy Technology Data Exchange (ETDEWEB)

    Winckler, N., E-mail: n.winckler@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Rybalchenko, A. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Shevelko, V.P. [P.N. Lebedev Physical Institute, 119991 Moscow (Russian Federation); Al-Turany, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); CERN, European Organization for Nuclear Research, 1211 Geneve 23 (Switzerland); Kollegger, T. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Stöhlker, Th. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Helmholtz-Institute Jena, D-07743 Jena (Germany); Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, D-07743 Jena (Germany)

    2017-02-01

    A detailed description of a recently developed BREIT computer code (Balance Rate Equations of Ion Transportation) for calculating charge-state fractions of ion beams passing through matter is presented. The code is based on the analytical solutions of the differential balance equations for the charge-state fractions as a function of the target thickness and can be used for calculating the ion evolutions in gaseous, solid and plasma targets. The BREIT code is available on-line and requires the charge-changing cross sections and initial conditions in the input file. The eigenvalue decomposition method, applied to obtain the analytical solutions of the rate equations, is described in the paper. Calculations of non-equilibrium and equilibrium charge-state fractions, performed by the BREIT code, are compared with experimental data and results of other codes for ion beams in gaseous and solid targets. Ability and limitations of the BREIT code are discussed in detail.

  11. A Modified Homogeneous Balance Method and Its Applications

    International Nuclear Information System (INIS)

    Liu Chunping

    2011-01-01

    A modified homogeneous balance method is proposed by improving some key steps in the homogeneous balance method. Bilinear equations of some nonlinear evolution equations are derived by using the modified homogeneous balance method. Generalized Boussinesq equation, KP equation, and mKdV equation are chosen as examples to illustrate our method. This approach is also applicable to a large variety of nonlinear evolution equations. (general)

  12. Population density equations for stochastic processes with memory kernels

    Science.gov (United States)

    Lai, Yi Ming; de Kamps, Marc

    2017-06-01

    We present a method for solving population density equations (PDEs)-a mean-field technique describing homogeneous populations of uncoupled neurons—where the populations can be subject to non-Markov noise for arbitrary distributions of jump sizes. The method combines recent developments in two different disciplines that traditionally have had limited interaction: computational neuroscience and the theory of random networks. The method uses a geometric binning scheme, based on the method of characteristics, to capture the deterministic neurodynamics of the population, separating the deterministic and stochastic process cleanly. We can independently vary the choice of the deterministic model and the model for the stochastic process, leading to a highly modular numerical solution strategy. We demonstrate this by replacing the master equation implicit in many formulations of the PDE formalism by a generalization called the generalized Montroll-Weiss equation—a recent result from random network theory—describing a random walker subject to transitions realized by a non-Markovian process. We demonstrate the method for leaky- and quadratic-integrate and fire neurons subject to spike trains with Poisson and gamma-distributed interspike intervals. We are able to model jump responses for both models accurately to both excitatory and inhibitory input under the assumption that all inputs are generated by one renewal process.

  13. On the Riemann solutions of the balance equations for steam and water flow in a porous medium

    NARCIS (Netherlands)

    Lambert, W.; Marchesin, D.; Bruining, J.

    2005-01-01

    Conservation laws have been used to model a variety of physical phenomena and therefore the theory for this class of equations is well developed. However, in many problems, such as transport of hot fluids and gases undergoing mass transfer, balance laws are required to describe the flow. As an

  14. submitter BREIT code: Analytical solution of the balance rate equations for charge-state evolutions of heavy-ion beams in matter

    CERN Document Server

    Winckler, N; Shevelko, V P; Al-Turany, M; Kollegger, T; Stöhlker, Th

    2017-01-01

    A detailed description of a recently developed BREIT computer code (Balance Rate Equations of Ion Transportation) for calculating charge-state fractions of ion beams passing through matter is presented. The code is based on the analytical solutions of the differential balance equations for the charge-state fractions as a function of the target thickness and can be used for calculating the ion evolutions in gaseous, solid and plasma targets. The BREIT code is available on-line and requires the charge-changing cross sections and initial conditions in the input file. The eigenvalue decomposition method, applied to obtain the analytical solutions of the rate equations, is described in the paper. Calculations of non-equilibrium and equilibrium charge-state fractions, performed by the BREIT code, are compared with experimental data and results of other codes for ion beams in gaseous and solid targets. Ability and limitations of the BREIT code are discussed in detail.

  15. Equation of material balance for systems of double porosity with layer of initial gas

    International Nuclear Information System (INIS)

    Niz, Eider; Hidrobo, Eduardo A; Penuela, Gherson; Ordonez, Anibal; Calderon, Zuly H

    2004-01-01

    The physical complexity associated to naturally fractured reservoirs calls for the use of more robust formulations of the Material-Balance Equation (MBE) for determining the initial hydrocarbon in place and predicting reservoir performance. In this paper, we present an improved version of the dual-porosity MBE for naturally fractured reservoirs, published by Penuela et al. (2001), including the existence of an initial gas phase in the reservoir. Considering that a fractured reservoir may be modeled either using different properties for each porous medium or with average values for the total system, two solution techniques based on each of these assumptions are proposed. Convenient arrangements of the equation allow us to estimate not only the original oil and gas volumes but also the relative storage capacity of the porous media (fractures and matrix) and the compressibility for the fractured and total systems. The new equation can be applied to a broader range of reservoirs due to its more general character. The consistency of the expression proposed has been tested with a set of synthetic models exhibiting different storage capacity in the fractures

  16. Critical Domain Problem for the Reaction–Telegraph Equation Model of Population Dynamics

    Directory of Open Access Journals (Sweden)

    Weam Alharbi

    2018-04-01

    Full Text Available A telegraph equation is believed to be an appropriate model of population dynamics as it accounts for the directional persistence of individual animal movement. Being motivated by the problem of habitat fragmentation, which is known to be a major threat to biodiversity that causes species extinction worldwide, we consider the reaction–telegraph equation (i.e., telegraph equation combined with the population growth on a bounded domain with the goal to establish the conditions of species survival. We first show analytically that, in the case of linear growth, the expression for the domain’s critical size coincides with the critical size of the corresponding reaction–diffusion model. We then consider two biologically relevant cases of nonlinear growth, i.e., the logistic growth and the growth with a strong Allee effect. Using extensive numerical simulations, we show that in both cases the critical domain size of the reaction–telegraph equation is larger than the critical domain size of the reaction–diffusion equation. Finally, we discuss possible modifications of the model in order to enhance the positivity of its solutions.

  17. An Innovative Approach to Balancing Chemical-Reaction Equations: A Simplified Matrix-Inversion Technique for Determining The Matrix Null Space

    OpenAIRE

    Thorne, Lawrence R.

    2011-01-01

    I propose a novel approach to balancing equations that is applicable to all chemical-reaction equations; it is readily accessible to students via scientific calculators and basic computer spreadsheets that have a matrix-inversion application. The new approach utilizes the familiar matrix-inversion operation in an unfamiliar and innovative way; its purpose is not to identify undetermined coefficients as usual, but, instead, to compute a matrix null space (or matrix kernel). The null space then...

  18. High-field transport of electrons and radiative effects using coupled force-balance and Fokker-Planck equations beyond the relaxation-time approximation

    International Nuclear Information System (INIS)

    Huang, Danhong; Apostolova, T.; Alsing, P.M.; Cardimona, D.A.

    2004-01-01

    The dynamics of a many-electron system under both dc and infrared fields is separated into a center-of-mass and a relative motion. The first-order force-balance equation is employed for the slow center-of-mass motion of electrons, and the Fokker-Planck equation is used for the ultrafast relative scattering motion of degenerate electrons. This approach allows us to include the anisotropic energy-relaxation process which has been neglected in the energy-balance equation in the past. It also leads us to include the anisotropic coupling to the incident infrared field with different polarizations. Based on this model, the transport of electrons is explored under strong dc and infrared fields by going beyond the relaxation-time approximation. The anisotropic dependence of the electron distribution function on the parallel and perpendicular kinetic energies of electrons is displayed with respect to the dc field direction, and the effect of anisotropic coupling to an incident infrared field with polarizations parallel and perpendicular to the applied dc electric field is shown. The heating of electrons is more accurately described beyond the energy-balance equation with the inclusion of an anisotropic coupling to the infrared field. The drift velocity of electrons is found to increase with the amplitude of the infrared field due to a suppressed momentum-relaxation process (or frictional force) under parallel polarization but decreases with the amplitude due to an enhanced momentum-relaxation process under perpendicular polarization

  19. Discrete bivariate population balance modelling of heteroaggregation processes.

    Science.gov (United States)

    Rollié, Sascha; Briesen, Heiko; Sundmacher, Kai

    2009-08-15

    Heteroaggregation in binary particle mixtures was simulated with a discrete population balance model in terms of two internal coordinates describing the particle properties. The considered particle species are of different size and zeta-potential. Property space is reduced with a semi-heuristic approach to enable an efficient solution. Aggregation rates are based on deterministic models for Brownian motion and stability, under consideration of DLVO interaction potentials. A charge-balance kernel is presented, relating the electrostatic surface potential to the property space by a simple charge balance. Parameter sensitivity with respect to the fractal dimension, aggregate size, hydrodynamic correction, ionic strength and absolute particle concentration was assessed. Results were compared to simulations with the literature kernel based on geometric coverage effects for clusters with heterogeneous surface properties. In both cases electrostatic phenomena, which dominate the aggregation process, show identical trends: impeded cluster-cluster aggregation at low particle mixing ratio (1:1), restabilisation at high mixing ratios (100:1) and formation of complex clusters for intermediate ratios (10:1). The particle mixing ratio controls the surface coverage extent of the larger particle species. Simulation results are compared to experimental flow cytometric data and show very satisfactory agreement.

  20. Global Existence Analysis of Cross-Diffusion Population Systems for Multiple Species

    Science.gov (United States)

    Chen, Xiuqing; Daus, Esther S.; Jüngel, Ansgar

    2018-02-01

    The existence of global-in-time weak solutions to reaction-cross-diffusion systems for an arbitrary number of competing population species is proved. The equations can be derived from an on-lattice random-walk model with general transition rates. In the case of linear transition rates, it extends the two-species population model of Shigesada, Kawasaki, and Teramoto. The equations are considered in a bounded domain with homogeneous Neumann boundary conditions. The existence proof is based on a refined entropy method and a new approximation scheme. Global existence follows under a detailed balance or weak cross-diffusion condition. The detailed balance condition is related to the symmetry of the mobility matrix, which mirrors Onsager's principle in thermodynamics. Under detailed balance (and without reaction) the entropy is nonincreasing in time, but counter-examples show that the entropy may increase initially if detailed balance does not hold.

  1. Parameter Estimates in Differential Equation Models for Population Growth

    Science.gov (United States)

    Winkel, Brian J.

    2011-01-01

    We estimate the parameters present in several differential equation models of population growth, specifically logistic growth models and two-species competition models. We discuss student-evolved strategies and offer "Mathematica" code for a gradient search approach. We use historical (1930s) data from microbial studies of the Russian biologist,…

  2. Well-Balanced Second-Order Approximation of the Shallow Water Equations With Friction via Continuous Galerkin Finite Elements

    Science.gov (United States)

    Quezada de Luna, M.; Farthing, M.; Guermond, J. L.; Kees, C. E.; Popov, B.

    2017-12-01

    The Shallow Water Equations (SWEs) are popular for modeling non-dispersive incompressible water waves where the horizontal wavelength is much larger than the vertical scales. They can be derived from the incompressible Navier-Stokes equations assuming a constant vertical velocity. The SWEs are important in Geophysical Fluid Dynamics for modeling surface gravity waves in shallow regimes; e.g., in the deep ocean. Some common geophysical applications are the evolution of tsunamis, river flooding and dam breaks, storm surge simulations, atmospheric flows and others. This work is concerned with the approximation of the time-dependent Shallow Water Equations with friction using explicit time stepping and continuous finite elements. The objective is to construct a method that is at least second-order accurate in space and third or higher-order accurate in time, positivity preserving, well-balanced with respect to rest states, well-balanced with respect to steady sliding solutions on inclined planes and robust with respect to dry states. Methods fulfilling the desired goals are common within the finite volume literature. However, to the best of our knowledge, schemes with the above properties are not well developed in the context of continuous finite elements. We start this work based on a finite element method that is second-order accurate in space, positivity preserving and well-balanced with respect to rest states. We extend it by: modifying the artificial viscosity (via the entropy viscosity method) to deal with issues of loss of accuracy around local extrema, considering a singular Manning friction term handled via an explicit discretization under the usual CFL condition, considering a water height regularization that depends on the mesh size and is consistent with the polynomial approximation, reducing dispersive errors introduced by lumping the mass matrix and others. After presenting the details of the method we show numerical tests that demonstrate the well-balanced

  3. Busy yet socially engaged: volunteering, work-life balance, and health in the working population.

    OpenAIRE

    Ramos Romualdo; Brauchli Rebecca; Bauer Georg; Wehner Theo; Hämmig Oliver

    2015-01-01

    OBJECTIVE To understand the relationship between volunteering and health in the overlooked yet highly engaged working population, adopting a contextualizing balance approach. We hypothesize that volunteering may function as a psychosocial resource, contributing to work-life balance and, ultimately, health. METHODS A total of 746 Swiss workers participated in an online survey; 35% (N = 264) were additionally volunteers in a nonprofit organization. We assessed volunteering, work-life balance...

  4. Population equations for degree-heterogenous neural networks

    Science.gov (United States)

    Kähne, M.; Sokolov, I. M.; Rüdiger, S.

    2017-11-01

    We develop a statistical framework for studying recurrent networks with broad distributions of the number of synaptic links per neuron. We treat each group of neurons with equal input degree as one population and derive a system of equations determining the population-averaged firing rates. The derivation rests on an assumption of a large number of neurons and, additionally, an assumption of a large number of synapses per neuron. For the case of binary neurons, analytical solutions can be constructed, which correspond to steps in the activity versus degree space. We apply this theory to networks with degree-correlated topology and show that complex, multi-stable regimes can result for increasing correlations. Our work is motivated by the recent finding of subnetworks of highly active neurons and the fact that these neurons tend to be connected to each other with higher probability.

  5. An age-structured population balance model for microbial dynamics

    Directory of Open Access Journals (Sweden)

    Duarte M.V.E.

    2003-01-01

    Full Text Available This work presents an age-structured population balance model (ASPBM for a bioprocess in a continuous stirred-tank fermentor. It relates the macroscopic properties and dynamic behavior of biomass to the operational parameters and microscopic properties of cells. Population dynamics is governed by two time- and age-dependent density functions for living and dead cells, accounting for the influence of substrate and dissolved oxygen concentrations on cell division, aging and death processes. The ASPBM described biomass and substrate oscillations in aerobic continuous cultures as experimentally observed. It is noteworthy that a small data set consisting of nonsegregated measurements was sufficient to adjust a complex segregated mathematical model.

  6. Nonequilibrium steady state in open quantum systems: Influence action, stochastic equation and power balance

    International Nuclear Information System (INIS)

    Hsiang, J.-T.; Hu, B.L.

    2015-01-01

    The existence and uniqueness of a steady state for nonequilibrium systems (NESS) is a fundamental subject and a main theme of research in statistical mechanics for decades. For Gaussian systems, such as a chain of classical harmonic oscillators connected at each end to a heat bath, and for classical anharmonic oscillators under specified conditions, definitive answers exist in the form of proven theorems. Answering this question for quantum many-body systems poses a challenge for the present. In this work we address this issue by deriving the stochastic equations for the reduced system with self-consistent backaction from the two baths, calculating the energy flow from one bath to the chain to the other bath, and exhibiting a power balance relation in the total (chain + baths) system which testifies to the existence of a NESS in this system at late times. Its insensitivity to the initial conditions of the chain corroborates to its uniqueness. The functional method we adopt here entails the use of the influence functional, the coarse-grained and stochastic effective actions, from which one can derive the stochastic equations and calculate the average values of physical variables in open quantum systems. This involves both taking the expectation values of quantum operators of the system and the distributional averages of stochastic variables stemming from the coarse-grained environment. This method though formal in appearance is compact and complete. It can also easily accommodate perturbative techniques and diagrammatic methods from field theory. Taken all together it provides a solid platform for carrying out systematic investigations into the nonequilibrium dynamics of open quantum systems and quantum thermodynamics. -- Highlights: •Nonequilibrium steady state (NESS) for interacting quantum many-body systems. •Derivation of stochastic equations for quantum oscillator chain with two heat baths. •Explicit calculation of the energy flow from one bath to the

  7. Stochastic population dynamic models as probability networks

    Science.gov (United States)

    M.E. and D.C. Lee. Borsuk

    2009-01-01

    The dynamics of a population and its response to environmental change depend on the balance of birth, death and age-at-maturity, and there have been many attempts to mathematically model populations based on these characteristics. Historically, most of these models were deterministic, meaning that the results were strictly determined by the equations of the model and...

  8. General particle transport equation. Final report

    International Nuclear Information System (INIS)

    Lafi, A.Y.; Reyes, J.N. Jr.

    1994-12-01

    The general objectives of this research are as follows: (1) To develop fundamental models for fluid particle coalescence and breakage rates for incorporation into statistically based (Population Balance Approach or Monte Carlo Approach) two-phase thermal hydraulics codes. (2) To develop fundamental models for flow structure transitions based on stability theory and fluid particle interaction rates. This report details the derivation of the mass, momentum and energy conservation equations for a distribution of spherical, chemically non-reacting fluid particles of variable size and velocity. To study the effects of fluid particle interactions on interfacial transfer and flow structure requires detailed particulate flow conservation equations. The equations are derived using a particle continuity equation analogous to Boltzmann's transport equation. When coupled with the appropriate closure equations, the conservation equations can be used to model nonequilibrium, two-phase, dispersed, fluid flow behavior. Unlike the Eulerian volume and time averaged conservation equations, the statistically averaged conservation equations contain additional terms that take into account the change due to fluid particle interfacial acceleration and fluid particle dynamics. Two types of particle dynamics are considered; coalescence and breakage. Therefore, the rate of change due to particle dynamics will consider the gain and loss involved in these processes and implement phenomenological models for fluid particle breakage and coalescence

  9. The water balance questionnaire: design, reliability and validity of a questionnaire to evaluate water balance in the general population.

    Science.gov (United States)

    Malisova, Olga; Bountziouka, Vassiliki; Panagiotakos, Demosthenes B; Zampelas, Antonis; Kapsokefalou, Maria

    2012-03-01

    There is a need to develop a questionnaire as a research tool for the evaluation of water balance in the general population. The water balance questionnaire (WBQ) was designed to evaluate water intake from fluid and solid foods and drinking water, and water loss from urine, faeces and sweat at sedentary conditions and physical activity. For validation purposes, the WBQ was administrated in 40 apparently healthy participants aged 22-57 years (37.5% males). Hydration indices in urine (24 h volume, osmolality, specific gravity, pH, colour) were measured through established procedures. Furthermore, the questionnaire was administered twice to 175 subjects to evaluate its reliability. Kendall's τ-b and the Bland and Altman method were used to assess the questionnaire's validity and reliability. The proposed WBQ to assess water balance in healthy individuals was found to be valid and reliable, and it could thus be a useful tool in future projects that aim to evaluate water balance.

  10. Exact traveling wave solutions of the Boussinesq equation

    International Nuclear Information System (INIS)

    Ding Shuangshuang; Zhao Xiqiang

    2006-01-01

    The repeated homogeneous balance method is used to construct exact traveling wave solutions of the Boussinesq equation, in which the homogeneous balance method is applied to solve the Riccati equation and the reduced nonlinear ordinary differential equation, respectively. Many new exact traveling wave solutions of the Boussinesq equation are successfully obtained

  11. Solving the radiation diffusion and energy balance equations using pseudo-transient continuation

    International Nuclear Information System (INIS)

    Shestakov, A.I.; Greenough, J.A.; Howell, L.H.

    2005-01-01

    We develop a scheme for the system coupling the radiation diffusion and matter energy balance equations. The method is based on fully implicit, first-order, backward Euler differencing; Picard-Newton iterations solve the nonlinear system. We show that iterating on the radiation energy density and the emission source is more robust. Since the Picard-Newton scheme may not converge for all initial conditions and time steps, pseudo-transient continuation (Ψtc) is introduced. The combined Ψtc-Picard-Newton scheme is analyzed. We derive conditions on the Ψtc parameter that guarantee physically meaningful iterates, e.g., positive energies. Successive Ψtc iterates are bounded and the radiation energy density and emission source tend to equilibrate. The scheme is incorporated into a multiply dimensioned, massively parallel, Eulerian, radiation-hydrodynamic computer program with automatic mesh refinement (AMR). Three examples are presented that exemplify the scheme's performance. (1) The Pomraning test problem that models radiation flow into cold matter. (2) A similar, but more realistic problem simulating the propagation of an ionization front into tenuous hydrogen gas with a Saha model for the equation-of-state. (3) A 2D axisymmetric (R,Z) simulation with real materials featuring jetting, radiatively driven, interacting shocks

  12. Greenland Ice Sheet Mass Balance

    Science.gov (United States)

    Reeh, N.

    1984-01-01

    Mass balance equation for glaciers; areal distribution and ice volumes; estimates of actual mass balance; loss by calving of icebergs; hydrological budget for Greenland; and temporal variations of Greenland mass balance are examined.

  13. Mathematical modeling and the two-phase constitutive equations

    International Nuclear Information System (INIS)

    Boure, J.A.

    1975-01-01

    The problems raised by the mathematical modeling of two-phase flows are summarized. The models include several kinds of equations, which cannot be discussed independently, such as the balance equations and the constitutive equations. A review of the various two-phase one-dimensional models proposed to date, and of the constitutive equations they imply, is made. These models are either mixture models or two-fluid models. Due to their potentialities, the two-fluid models are discussed in more detail. To avoid contradictions, the form of the constitutive equations involved in two-fluid models must be sufficiently general. A special form of the two-fluid models, which has particular advantages, is proposed. It involves three mixture balance equations, three balance equations for slip and thermal non-equilibriums, and the necessary constitutive equations [fr

  14. Galerkin method for unsplit 3-D Dirac equation using atomically/kinetically balanced B-spline basis

    International Nuclear Information System (INIS)

    Fillion-Gourdeau, F.; Lorin, E.; Bandrauk, A.D.

    2016-01-01

    A Galerkin method is developed to solve the time-dependent Dirac equation in prolate spheroidal coordinates for an electron–molecular two-center system. The initial state is evaluated from a variational principle using a kinetic/atomic balanced basis, which allows for an efficient and accurate determination of the Dirac spectrum and eigenfunctions. B-spline basis functions are used to obtain high accuracy. This numerical method is used to compute the energy spectrum of the two-center problem and then the evolution of eigenstate wavefunctions in an external electromagnetic field.

  15. The effects of a multi-axis balance board intervention program in an elderly population.

    Science.gov (United States)

    Dougherty, John; Kancel, Anne; Ramar, Cassandra; Meacham, Crystal; Derrington, Stephen

    2011-01-01

    Balance is a major issue facing the geriatric population. Nine participants from a local community center for seniors completed a five-week study to assess improvement in balance. Measures of balance, performance times, and scores on the Berg Balance Scale (BBS) and the Wii Fit Age (WFA) were recorded before and after the entire intervention. An analysis of variance (ANOVA) with repeated measures was used to assess change in BBS and WFA scores. An analysis of covariance with repeated measures was used to asses the impact of possible contributing factors of age, gender, BMI and total balance board training time over the five-week period. The analysis indicated that use of the Indo Balance Board three times a week for ten minutes can significantly improve balance and potentially decrease the risk of falls, as measured by the BBS. Age was the only factor that significantly influenced balance (p = .006). These improvements are postulated to be due to an increase in subjects' core and lower extremity muscle strength and improved proprioception; a result of balance board usage.

  16. Synthesis of Dynamically Balanced Mechanisms by Using Counter-Rotary Countermass Balanced Double Pendula

    NARCIS (Netherlands)

    van der Wijk, V.; Herder, Justus Laurens

    2009-01-01

    Complete dynamic balancing principles still cannot avoid a substantial increase in mass and inertia. In addition, the conditions for dynamic balance and inertia equations can be complicated to derive. This article shows how a double pendulum, which is fully dynamically balanced using counter-rotary

  17. Population balance models: a useful complementary modelling framework for future WWTP modelling

    DEFF Research Database (Denmark)

    Nopens, Ingmar; Torfs, Elena; Ducoste, Joel

    2015-01-01

    Population balance models (PBMs) represent a powerful modelling framework for the description of the dynamics of properties that are characterised by distributions. This distribution of properties under transient conditions has been demonstrated in many chemical engineering applications. Modelling...

  18. Population Balance Models: A useful complementary modelling framework for future WWTP modelling

    DEFF Research Database (Denmark)

    Nopens, Ingmar; Torfs, Elena; Ducoste, Joel

    2014-01-01

    Population Balance Models (PBMs) represent a powerful modelling framework for the description of the dynamics of properties that are characterised by statistical distributions. This has been demonstrated in many chemical engineering applications. Modelling efforts of several current and future unit...

  19. Nets solution of flow for gases, using the Balance Pattern of Nodes and the method of linealization of equations

    International Nuclear Information System (INIS)

    Narvaez, Paulo Cesar

    1999-01-01

    The dimension of nets of distribution of gases is a complex problem, so much for the diversity of the phenomena that they are presented, like for the variation of the properties of the fluids, especially, the density for effect of the changes in the pressure along the net. This work presents a model for its simulation starting from the deduction of the general equation of flow in stable and isothermal state, its inclusion in the pattern of balance of nodes and the solution of this for the method of linealization of equations. Additionally, a summary of the empiric equations more used is made for the calculation of the fall of pressure for gases flowing in pipes and an example that it illustrates the application of the pattern and the developed method

  20. The Relationship Between Pedometer-Determined Ambulatory Activity and Balance Variables Within an Older Adult Population

    OpenAIRE

    Campbell, Candice; Kress, Jeff; Schroeder, Jan; Donlin, Ayla; Rozenek, Ralph

    2016-01-01

    The purpose of this investigation was to determine the differences between gender, physical activity level, and balance in an older adult population. A secondary purpose was to examine the relationship between pedometer-determined ambulatory activity and balance. Forty-six older adults aged 73.7 ± 6.2 years participated in the study. Participants completed the Fullerton Advanced Balance (FAB) Scale and completed a 2-week daily step recording to determine average steps taken per day. Low-level...

  1. Range expansion of heterogeneous populations.

    Science.gov (United States)

    Reiter, Matthias; Rulands, Steffen; Frey, Erwin

    2014-04-11

    Risk spreading in bacterial populations is generally regarded as a strategy to maximize survival. Here, we study its role during range expansion of a genetically diverse population where growth and motility are two alternative traits. We find that during the initial expansion phase fast-growing cells do have a selective advantage. By contrast, asymptotically, generalists balancing motility and reproduction are evolutionarily most successful. These findings are rationalized by a set of coupled Fisher equations complemented by stochastic simulations.

  2. Busy yet socially engaged: volunteering, work-life balance, and health in the working population.

    Science.gov (United States)

    Ramos, Romualdo; Brauchli, Rebecca; Bauer, Georg; Wehner, Theo; Hämmig, Oliver

    2015-02-01

    To understand the relationship between volunteering and health in the overlooked yet highly engaged working population, adopting a contextualizing balance approach. We hypothesize that volunteering may function as a psychosocial resource, contributing to work-life balance and, ultimately, health. A total of 746 Swiss workers participated in an online survey; 35% (N = 264) were additionally volunteers in a nonprofit organization. We assessed volunteering, work-life balance perceptions, paid job demands, and resources and health outcomes. After controlling for job characteristics, volunteering was associated with less work-life conflict, burnout and stress, and better positive mental health. Results further revealed that balance perceptions partly explained the relationship between volunteering and health. Volunteering, albeit energy and time-consuming, may contribute to a greater sense of balance for people in the workforce, which might, in turn, positively influence health.

  3. Simultaneous Balancing and Model Reduction of Switched Linear Systems

    OpenAIRE

    Monshizadeh, Nima; Trentelman, Hendrikus; Camlibel, M.K.

    2011-01-01

    In this paper, first, balanced truncation of linear systems is revisited. Then, simultaneous balancing of multiple linear systems is investigated. Necessary and sufficient conditions are introduced to identify the case where simultaneous balancing is possible. The validity of these conditions is not limited to a certain type of balancing, and they are applicable for different types of balancing corresponding to different equations, like Lyapunov or Riccati equations. The results obtained are ...

  4. Non-Abelian plasmons and their kinetics equation

    International Nuclear Information System (INIS)

    Zheng Xiaoping; Li Jiarong

    1998-01-01

    After the fluctuated modes in QGP are treated as plasmons, the kinetics equation for the plasmons in linear approximation is established starting from Yang-Mills fields equation. The kinetics equation can be considered as the balance equation for the number of plasmons, which indicates the balance of the number variation (growth or damping) in space and time because of their motion with velocities that equal to the wave's group velocity and the emission or absorption of plasmons by plasma particles

  5. Ordinary differential equations

    CERN Document Server

    Greenberg, Michael D

    2014-01-01

    Features a balance between theory, proofs, and examples and provides applications across diverse fields of study Ordinary Differential Equations presents a thorough discussion of first-order differential equations and progresses to equations of higher order. The book transitions smoothly from first-order to higher-order equations, allowing readers to develop a complete understanding of the related theory. Featuring diverse and interesting applications from engineering, bioengineering, ecology, and biology, the book anticipates potential difficulties in understanding the various solution steps

  6. The effect of visual biofeedback on balance in elderly population: a systematic review

    Directory of Open Access Journals (Sweden)

    Alhasan H

    2017-03-01

    Full Text Available Hammad Alhasan,1 Victoria Hood,2 Frederick Mainwaring2 1Physiotherapy Department, Faculty of Applied Medical Science, Umm al-Qura University, Mecca, Kingdom of Saudi Arabia; 2School of Health Science, University of Nottingham, Nottingham, Nottinghamshire, UK Background: Balance is commonly affected by multiple factors, especially among the elderly population. Visual biofeedback (VBF is an intervention tool that can be used in balance rehabilitation.Aim: This study aimed to systematically review randomized controlled trials that examine whether VBF training is effective in improving balance in an elderly population.Data sources: Three databases were searched: CIAHL, EMBASE, and MEDLINE. The searches were limited to the period from 2010 to 2016.Eligibility criteria: Healthy adults, aged ≥65 years, with no specific disorders were included. Interventions were any VBF intervention with the aim of improving balance and were compared to no intervention, traditional exercises, placebo, or standard care. The outcome measures were balance as measured by any validated outcome measure.Studies appraisal method: The Physiotherapy Evidence Database quality assessment tool and The Cochrane Collaboration tool for assessing risk of bias were used by two independent authors (HA and FM in order to appraise the included studies.Results: The database search resulted in 879 articles, of which five papers were included. VBF was compared to no intervention, a placebo, and traditional exercise. The total number of participants in all the five included studies was 181, with a mean age of 74.3 years (standard deviation 6.7. Two studies were rated as high-quality studies, and three were rated as fair quality.Conclusion: Engaging elderly people living in the community in VBF training was found to be effective and could improve their balance ability. However, the variation between studies in methodology, intervention protocol, and outcomes utilized made it difficult to

  7. Evaluation of seasonality on total water intake, water loss and water balance in the general population in Greece.

    Science.gov (United States)

    Malisova, O; Bountziouka, V; Panagiotakos, D Β; Zampelas, A; Kapsokefalou, M

    2013-07-01

    Water balance is achieved when water intake from solid and fluid foods and drinking water meets water losses, mainly in sweat, urine and faeces. Seasonality, particularly in Mediterranean countries that have a hot summer, may affect water loss and consequently water balance. Water balance has not been estimated before on a population level and the effect of seasonality has not been evaluated. The present study aimed to compare water balance, intake and loss in summer and winter in a sample of the general population in Greece. The Water Balance Questionnaire (WBQ) was used to evaluate water balance, estimating water intake and loss in summer (n = 480) and in winter (n = 412) on a stratified sample of the general population in Athens, Greece. In winter, mean (SD) water balance was -63 (1478) mL/day(-1) , mean (SD)water intake was 2892 (987) mL/day(-1) and mean (quartile range) water loss was 2637 (1810-3922) mL/day(-1) . In summer, mean (SD) water balance was -58 (2150) mL/day(-1) , mean (SD) water intake was 3875 (1373) mL/day(-1) and mean (quartile range) water loss was 3635 (2365-5258) mL/day(-1) . Water balance did not differ between summer and winter (P = 0.96); however, the data distribution was different; in summer, approximately 8% more participants were falling in the low and high water balance categories. Differences in water intake from different sources were identified (P balance in summer and winter was not different. However, water intake and loss were approximately 40% higher in summer than in winter. More people were falling in the low and high water balance categories in summer when comparing the distribution on water balance in winter. © 2013 The Authors Journal of Human Nutrition and Dietetics © 2013 The British Dietetic Association Ltd.

  8. Adjusting the general growth balance method for migration

    OpenAIRE

    Hill, Kenneth; Queiroz, Bernardo

    2010-01-01

    Death distribution methods proposed for death registration coverage by comparison with census age distributions assume no net migration. This assumption makes it problematic to apply these methods to sub-national and national populations affected by substantial net migration. In this paper, we propose and explore a two-step process in which the Growth Balance Equation is first used to estimate net migration rates, using a model of age-specific migration, and then it is used to compare the obs...

  9. Geochemical mole-balance modeling with uncertain data

    Science.gov (United States)

    Parkhurst, David L.

    1997-01-01

    Geochemical mole-balance models are sets of chemical reactions that quantitatively account for changes in the chemical and isotopic composition of water along a flow path. A revised mole-balance formulation that includes an uncertainty term for each chemical and isotopic datum is derived. The revised formulation is comprised of mole-balance equations for each element or element redox state, alkalinity, electrons, solvent water, and each isotope; a charge-balance equation and an equation that relates the uncertainty terms for pH, alkalinity, and total dissolved inorganic carbon for each aqueous solution; inequality constraints on the size of the uncertainty terms; and inequality constraints on the sign of the mole transfer of reactants. The equations and inequality constraints are solved by a modification of the simplex algorithm combined with an exhaustive search for unique combinations of aqueous solutions and reactants for which the equations and inequality constraints can be solved and the uncertainty terms minimized. Additional algorithms find only the simplest mole-balance models and determine the ranges of mixing fractions for each solution and mole transfers for each reactant that are consistent with specified limits on the uncertainty terms. The revised formulation produces simpler and more robust mole-balance models and allows the significance of mixing fractions and mole transfers to be evaluated. In an example from the central Oklahoma aquifer, inclusion of up to 5% uncertainty in the chemical data can reduce the number of reactants in mole-balance models from seven or more to as few as three, these being cation exchange, dolomite dissolution, and silica precipitation. In another example from the Madison aquifer, inclusion of the charge-balance constraint requires significant increases in the mole transfers of calcite, dolomite, and organic matter, which reduce the estimated maximum carbon 14 age of the sample by about 10,000 years, from 22,700 years to

  10. Application of the heat-balance and refined integral methods to the Korteweg-de Vries equation

    Directory of Open Access Journals (Sweden)

    Myers Timothy G.

    2009-01-01

    Full Text Available In this paper we consider approximate travelling wave solutions to the Korteweg-de Vries equation. The heat-balance integral method is first applied to the problem, using two different quartic approximating functions, and then the refined integral method is investigated. We examine two types of solution, chosen by matching the wave speed to that of the exact solution and by imposing the same area. The first set of solutions is generally better with an error that is fixed in time. The second set of solutions has an error that grows with time. This is shown to be due to slight discrepancies in the wave speed.

  11. Periodic solutions of first-order functional differential equations in population dynamics

    CERN Document Server

    Padhi, Seshadev; Srinivasu, P D N

    2014-01-01

    This book provides cutting-edge results on the existence of multiple positive periodic solutions of first-order functional differential equations. It demonstrates how the Leggett-Williams fixed-point theorem can be applied to study the existence of two or three positive periodic solutions of functional differential equations with real-world applications, particularly with regard to the Lasota-Wazewska model, the Hematopoiesis model, the Nicholsons Blowflies model, and some models with Allee effects. Many interesting sufficient conditions are given for the dynamics that include nonlinear characteristics exhibited by population models. The last chapter provides results related to the global appeal of solutions to the models considered in the earlier chapters. The techniques used in this book can be easily understood by anyone with a basic knowledge of analysis. This book offers a valuable reference guide for students and researchers in the field of differential equations with applications to biology, ecology, a...

  12. Dynamic Analysis of a Pendulum Dynamic Automatic Balancer

    Directory of Open Access Journals (Sweden)

    Jin-Seung Sohn

    2007-01-01

    Full Text Available The automatic dynamic balancer is a device to reduce the vibration from unbalanced mass of rotors. Instead of considering prevailing ball automatic dynamic balancer, pendulum automatic dynamic balancer is analyzed. For the analysis of dynamic stability and behavior, the nonlinear equations of motion for a system are derived with respect to polar coordinates by the Lagrange's equations. The perturbation method is applied to investigate the dynamic behavior of the system around the equilibrium position. Based on the linearized equations, the dynamic stability of the system around the equilibrium positions is investigated by the eigenvalue analysis.

  13. Utility rate equations of group population dynamics in biological and social systems.

    Directory of Open Access Journals (Sweden)

    Vyacheslav I Yukalov

    Full Text Available We present a novel system of equations to describe the evolution of self-organized structured societies (biological or human composed of several trait groups. The suggested approach is based on the combination of ideas employed in the theory of biological populations, system theory, and utility theory. The evolution equations are defined as utility rate equations, whose parameters are characterized by the utility of each group with respect to the society as a whole and by the mutual utilities of groups with respect to each other. We analyze in detail the cases of two groups (cooperators and defectors and of three groups (cooperators, defectors, and regulators and find that, in a self-organized society, neither defectors nor regulators can overpass the maximal fractions of about [Formula: see text] each. This is in agreement with the data for bee and ant colonies. The classification of societies by their distance from equilibrium is proposed. We apply the formalism to rank the countries according to the introduced metric quantifying their relative stability, which depends on the cost of defectors and regulators as well as their respective population fractions. We find a remarkable concordance with more standard economic ranking based, for instance, on GDP per capita.

  14. Utility Rate Equations of Group Population Dynamics in Biological and Social Systems

    Science.gov (United States)

    Yukalov, Vyacheslav I.; Yukalova, Elizaveta P.; Sornette, Didier

    2013-01-01

    We present a novel system of equations to describe the evolution of self-organized structured societies (biological or human) composed of several trait groups. The suggested approach is based on the combination of ideas employed in the theory of biological populations, system theory, and utility theory. The evolution equations are defined as utility rate equations, whose parameters are characterized by the utility of each group with respect to the society as a whole and by the mutual utilities of groups with respect to each other. We analyze in detail the cases of two groups (cooperators and defectors) and of three groups (cooperators, defectors, and regulators) and find that, in a self-organized society, neither defectors nor regulators can overpass the maximal fractions of about each. This is in agreement with the data for bee and ant colonies. The classification of societies by their distance from equilibrium is proposed. We apply the formalism to rank the countries according to the introduced metric quantifying their relative stability, which depends on the cost of defectors and regulators as well as their respective population fractions. We find a remarkable concordance with more standard economic ranking based, for instance, on GDP per capita. PMID:24386163

  15. Solving Nonlinear Coupled Differential Equations

    Science.gov (United States)

    Mitchell, L.; David, J.

    1986-01-01

    Harmonic balance method developed to obtain approximate steady-state solutions for nonlinear coupled ordinary differential equations. Method usable with transfer matrices commonly used to analyze shaft systems. Solution to nonlinear equation, with periodic forcing function represented as sum of series similar to Fourier series but with form of terms suggested by equation itself.

  16. Energy intake underreporting of adults in a household survey: the impact of using a population specific basal metabolic rate equation

    Directory of Open Access Journals (Sweden)

    Danielle Ribeiro de Souza

    2015-04-01

    Full Text Available The purpose of the present study was to identify energy intake (EI underreporting and to estimate the impact of using a population specific equation for the basal metabolic rate (BMR in a probability sample of adults from Niterói, Rio de Janeiro State, Brazil. A sample of 1,726 subjects participated in the study. EI was assessed by a 24-hour dietary recall and EI/BMR was computed with BMR estimated using internationally recommended equations as well as specific equations developed for the adult population of Niterói. Mean EI was 1,570.9 and 2,188.8kcal.day-1 for women and men, respectively. EI decreased with increasing age in both men and women. BMR estimated by the Brazilian equation was significantly lower than the values estimated by the international equation for all age, sex and nutritional status groups. In general, EI underreporting was found in at least 50% of the population, higher in women, and increased with increasing age and body mass index (BMI. The results of the present study confirm that EI is underreported, even when BMR is estimated using population-specific equations.

  17. A mathematical model of a crocodilian population using delay-differential equations.

    Science.gov (United States)

    Gallegos, Angela; Plummer, Tenecia; Uminsky, David; Vega, Cinthia; Wickman, Clare; Zawoiski, Michael

    2008-11-01

    The crocodilia have multiple interesting characteristics that affect their population dynamics. They are among several reptile species which exhibit temperature-dependent sex determination (TSD) in which the temperature of egg incubation determines the sex of the hatchlings. Their life parameters, specifically birth and death rates, exhibit strong age-dependence. We develop delay-differential equation (DDE) models describing the evolution of a crocodilian population. In using the delay formulation, we are able to account for both the TSD and the age-dependence of the life parameters while maintaining some analytical tractability. In our single-delay model we also find an equilibrium point and prove its local asymptotic stability. We numerically solve the different models and investigate the effects of multiple delays on the age structure of the population as well as the sex ratio of the population. For all models we obtain very strong agreement with the age structure of crocodilian population data as reported in Smith and Webb (Aust. Wild. Res. 12, 541-554, 1985). We also obtain reasonable values for the sex ratio of the simulated population.

  18. Equating error in observed-score equating

    NARCIS (Netherlands)

    van der Linden, Willem J.

    2006-01-01

    Traditionally, error in equating observed scores on two versions of a test is defined as the difference between the transformations that equate the quantiles of their distributions in the sample and population of test takers. But it is argued that if the goal of equating is to adjust the scores of

  19. A Novel Approach to Population Balance Modeling of Reactive Polymer Modification Leading to Branching

    NARCIS (Netherlands)

    Kryven, I.; Iedema, P.D.

    2013-01-01

    The mathematical treatment of polymer modification systems, described by population balances containing convolution is discussed. The two-dimensional case (molecular weight vs. number of branch points) was considered by utilizing approximations of distributions, expanding them in terms of Gaussian

  20. Diffusion approximations to the chemical master equation only have a consistent stochastic thermodynamics at chemical equilibrium.

    Science.gov (United States)

    Horowitz, Jordan M

    2015-07-28

    The stochastic thermodynamics of a dilute, well-stirred mixture of chemically reacting species is built on the stochastic trajectories of reaction events obtained from the chemical master equation. However, when the molecular populations are large, the discrete chemical master equation can be approximated with a continuous diffusion process, like the chemical Langevin equation or low noise approximation. In this paper, we investigate to what extent these diffusion approximations inherit the stochastic thermodynamics of the chemical master equation. We find that a stochastic-thermodynamic description is only valid at a detailed-balanced, equilibrium steady state. Away from equilibrium, where there is no consistent stochastic thermodynamics, we show that one can still use the diffusive solutions to approximate the underlying thermodynamics of the chemical master equation.

  1. Fluctuation and thermal energy balance for drift-wave turbulence

    International Nuclear Information System (INIS)

    Kim, Chang-Bae; Horton, W.

    1990-05-01

    Energy conservation for the drift-wave system is shown to be separated into the wave-energy power balance equation and an ambient thermal-energy transport equation containing the anomalous transport fluxes produced by the fluctuations. The wave energy equation relates the wave energy density and wave energy flux to the anomalous transport flux and the dissipation of the fluctuations. The thermal balance equation determines the evolution of the temperature profiles from the divergence of the anomalous heat flux, the collisional heating and cooling mechanisms and the toroidal pumping effect. 16 refs., 1 tab

  2. Fluctuation and thermal energy balance for drift-wave turbulence

    International Nuclear Information System (INIS)

    Changbae Kim; Horton, W.

    1991-01-01

    Energy conservation for the drift-wave system is shown to be separated into the wave-energy power balance equation and an ambient thermal-energy transport equation containing the anomalous transport fluxes produced by the fluctuations. The wave energy equation relates the wave energy density and wave energy flux to the anomalous transport flux and the dissipation of the fluctuations. The thermal balance equation determines the evolution of the temperature profiles from the divergence of the anomalous heat flux, the collisional heating and cooling mechanisms and the toroidal pumping effect. (author)

  3. Identifying footprints of directional and balancing selection in marine and freshwater three-spined stickleback (Gasterosteus aculeatus) populations.

    Science.gov (United States)

    Mäkinen, H S; Cano, J M; Merilä, J

    2008-08-01

    Natural selection is expected to leave an imprint on the neutral polymorphisms at the adjacent genomic regions of a selected gene. While directional selection tends to reduce within-population genetic diversity and increase among-population differentiation, the reverse is expected under balancing selection. To identify targets of natural selection in the three-spined stickleback (Gasterosteus aculeatus) genome, 103 microsatellite and two indel markers including expressed sequence tags (EST) and quantitative trait loci (QTL)-associated loci, were genotyped in four freshwater and three marine populations. The results indicated that a high proportion of loci (14.7%) might be affected by balancing selection and a lower proportion (2.8%) by directional selection. The strongest signatures of directional selection were detected in a microsatellite locus and two indel markers located in the intronic regions of the Eda-gene coding for the number of lateral plates. Yet, other microsatellite loci previously found to be informative in QTL-mapping studies revealed no signatures of selection. Two novel microsatellite loci (Stn12 and Stn90) located in chromosomes I and VIII, respectively, showed signals of directional selection and might be linked to genomic regions containing gene(s) important for adaptive divergence. Although the coverage of the total genomic content was relatively low, the predominance of balancing selection signals is in agreement with the contention that balancing, rather than directional selection is the predominant mode of selection in the wild.

  4. Nutrition, Balance and Fear of Falling as Predictors of Risk for Falls among Filipino Elderly in Nursing Homes: A Structural Equation Model (SEM)

    Science.gov (United States)

    de Guzman, Allan B.; Ines, Joanna Louise C.; Inofinada, Nina Josefa A.; Ituralde, Nielson Louie J.; Janolo, John Robert E.; Jerezo, Jnyv L.; Jhun, Hyae Suk J.

    2013-01-01

    While a number of empirical studies have been conducted regarding risk for falls among the elderly, there is still a paucity of similar studies in a developing country like the Philippines. This study purports to test through Structural Equation Modeling (SEM) a model that shows the interaction between and among nutrition, balance, fear of…

  5. A Carleman estimate and the balancing principle in the quasi-reversibility method for solving the Cauchy problem for the Laplace equation

    International Nuclear Information System (INIS)

    Cao Hui; Pereverzev, Sergei V; Klibanov, Michael V

    2009-01-01

    The quasi-reversibility method of solving the Cauchy problem for the Laplace equation in a bounded domain Ω is considered. With the help of the Carleman estimation technique improved error and stability bounds in a subdomain Ω σ is a subset of Ω are obtained. This paves the way for the use of the balancing principle for an a posteriori choice of the regularization parameter ε in the quasi-reversibility method. As an adaptive regularization parameter choice strategy, the balancing principle does not require a priori knowledge of either the solution smoothness or a constant K appearing in the stability bound estimation. Nevertheless, this principle allows an a posteriori parameter choice that up to a controllable constant achieves the best accuracy guaranteed by the Carleman estimate

  6. Development of the balance equations model for calculation of ion charge-state distribution in ECR ion sources

    International Nuclear Information System (INIS)

    Filippov, A.V.; Shirkov, G.D.; Consoli, F.; Gammino, S.; Ciavola, G.; Celona, L.; Barbarino, S.

    2008-01-01

    The investigation of the widespread model for the calculation of ion charge-state distributions (CSD) in electron cyclotron-resonance ion source based on the set of balance equations is given. The modification of this model that allows one to describe the confinement and accumulation processes of highly charged ions in ECR plasma for gas mixing case more precisely is discussed. The new approach for the time confinement calculation (ions and electrons) based on the theory of Pastukhov is offered, viz. - calculation of confinement times during two step minimization of special type functionals. The results obtained by this approach have been compared with available experimental data

  7. Exact solutions of generalized Zakharov and Ginzburg-Landau equations

    International Nuclear Information System (INIS)

    Zhang Jinliang; Wang Mingliang; Gao Kequan

    2007-01-01

    By using the homogeneous balance principle, the exact solutions of the generalized Zakharov equations and generalized Ginzburg-Landau equation are obtained with the aid of a set of subsidiary higher-order ordinary differential equations (sub-equations for short)

  8. The Influence of Cognitive Reasoning Level, Cognitive Restructuring Ability, Disembedding Ability, Working Memory Capacity, and Prior Knowledge On Students' Performance On Balancing Equations by Inspection.

    Science.gov (United States)

    Staver, John R.; Jacks, Tom

    1988-01-01

    Investigates the influence of five cognitive variables on high school students' performance on balancing chemical equations by inspection. Reports that reasoning, restructuring, and disembedding variables could be a single variable, and that working memory capacity does not influence overall performance. Results of hierarchical regression analysis…

  9. The Effectiveness of a Computer-Assisted Instruction Package in Supplementing Teaching of Selected Concepts in High School Chemistry: Writing Formulas and Balancing Chemical Equations.

    Science.gov (United States)

    Wainwright, Camille L.

    Four classes of high school chemistry students (N=108) were randomly assigned to experimental and control groups to investigate the effectiveness of a computer assisted instruction (CAI) package during a unit on writing/naming of chemical formulas and balancing equations. Students in the experimental group received drill, review, and reinforcement…

  10. Application Of A Balanced Adder-Subtractor In The Solution Of ...

    African Journals Online (AJOL)

    A balanced adder-subtractor employing operational amplifier is used to solve simultaneous linear equations. A pair of simultaneous linear equation with two unknowns have been considered for the design of the balanced adder-subtractor operated from a 6- volts d.c power source. A general purpose operational amplifier, ...

  11. Multiphase flow analysis using population balance modeling bubbles, drops and particles

    CERN Document Server

    Yeoh, Guan Heng; Tu, Jiyuan

    2013-01-01

    Written by leading multiphase flow and CFD experts, this book enables engineers and researchers to understand the use of PBM and CFD frameworks. Population balance approaches can now be used in conjunction with CFD, effectively driving more efficient and effective multiphase flow processes. Engineers familiar with standard CFD software, including ANSYS-CFX and ANSYS-Fluent, will be able to use the tools and approaches presented in this book in the effective research, modeling and control of multiphase flow problems. Builds a complete understanding of the theory behind the

  12. Bridging the Knowledge Gaps between Richards' Equation and Budyko Equation

    Science.gov (United States)

    Wang, D.

    2017-12-01

    The empirical Budyko equation represents the partitioning of mean annual precipitation into evaporation and runoff. Richards' equation, based on Darcy's law, represents the movement of water in unsaturated soils. The linkage between Richards' equation and Budyko equation is presented by invoking the empirical Soil Conservation Service curve number (SCS-CN) model for computing surface runoff at the event-scale. The basis of the SCS-CN method is the proportionality relationship, i.e., the ratio of continuing abstraction to its potential is equal to the ratio of surface runoff to its potential value. The proportionality relationship can be derived from the Richards' equation for computing infiltration excess and saturation excess models at the catchment scale. Meanwhile, the generalized proportionality relationship is demonstrated as the common basis of SCS-CN method, monthly "abcd" model, and Budyko equation. Therefore, the linkage between Darcy's law and the emergent pattern of mean annual water balance at the catchment scale is presented through the proportionality relationship.

  13. Harmonic and power balance tools for tapping-mode atomic force microscope

    International Nuclear Information System (INIS)

    Sebastian, A.; Salapaka, M. V.; Chen, D. J.; Cleveland, J. P.

    2001-01-01

    The atomic force microscope (AFM) is a powerful tool for investigating surfaces at atomic scales. Harmonic balance and power balance techniques are introduced to analyze the tapping-mode dynamics of the atomic force microscope. The harmonic balance perspective explains observations hitherto unexplained in the AFM literature. A nonconservative model for the cantilever - sample interaction is developed. The energy dissipation in the sample is studied and the resulting power balance equations combined with the harmonic balance equations are used to estimate the model parameters. Experimental results confirm that the harmonic and power balance tools can be used effectively to predict the behavior of the tapping cantilever. [copyright] 2001 American Institute of Physics

  14. Saturation and linear transport equation

    International Nuclear Information System (INIS)

    Kutak, K.

    2009-03-01

    We show that the GBW saturation model provides an exact solution to the one dimensional linear transport equation. We also show that it is motivated by the BK equation considered in the saturated regime when the diffusion and the splitting term in the diffusive approximation are balanced by the nonlinear term. (orig.)

  15. Structural redundancy of data from wastewater treatment systems. Determination of individual balance equations.

    Science.gov (United States)

    Spindler, A

    2014-06-15

    Although data reconciliation is intensely applied in process engineering, almost none of its powerful methods are employed for validation of operational data from wastewater treatment plants. This is partly due to some prerequisites that are difficult to meet including steady state, known variances of process variables and absence of gross errors. However, an algorithm can be derived from the classical approaches to data reconciliation that allows to find a comprehensive set of equations describing redundancy in the data when measured and unmeasured variables (flows and concentrations) are defined. This is a precondition for methods of data validation based on individual mass balances such as CUSUM charts. The procedure can also be applied to verify the necessity of existing or additional measurements with respect to the improvement of the data's redundancy. Results are given for a large wastewater treatment plant. The introduction aims at establishing a link between methods known from data reconciliation in process engineering and their application in wastewater treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Extended rate equations

    International Nuclear Information System (INIS)

    Shore, B.W.

    1981-01-01

    The equations of motion are discussed which describe time dependent population flows in an N-level system, reviewing the relationship between incoherent (rate) equations, coherent (Schrodinger) equations, and more general partially coherent (Bloch) equations. Approximations are discussed which replace the elaborate Bloch equations by simpler rate equations whose coefficients incorporate long-time consequences of coherence

  17. Computer-Simulation of Balance Handling

    NARCIS (Netherlands)

    Massen, C.H.; Swüste, C.H.W.; Robens, E.; Poulis, J.A.

    1999-01-01

    Several decades ago, when working in the field of magnetism, we had to use a balance the sensitivity of which was limited only by Brownian motion. This balance was a very slow one and to calculate the moment of force measured by it we used its equation of motion, T=Ja+ka+Ca, where we measured the

  18. A structural equation model of the relationship between muscle strength, balance performance, walking endurance and community integration in stroke survivors.

    Directory of Open Access Journals (Sweden)

    P W H Kwong

    Full Text Available To use structural equation modelling (SEM to determine (1 the direct and indirect associations of strength of paretic lower limb muscles with the level of community integration, and (2 the direct association of walking endurance and balance performance with the level of community integration in community-dwelling stroke survivors.In this cross-sectional study of 105 stroke survivors, the Subjective Index of Physical and Social Outcome (SIPSO was used to measure the level of community integration. Lower-limb strength measures included isometric paretic ankle strength and isokinetic paretic knee peak torque. The Berg Balance Scale (BBS and the 6-minute walk test (6MWT were used to evaluate balance performance and walking endurance, respectively.SEM revealed that the distance walked on the 6MWT had the strongest direct association with the SIPSO score (β = 0.41, p <0.001. An increase of one standard deviation in the 6MWT distance resulted in an increase of 0.41 standard deviations in the SIPSO score. Moreover, dorsiflexion strength (β = 0.18, p = 0.044 and the BBS score (β = 0.21, p = 0.021 had direct associations with the SIPSO score.The results of the proposed model suggest that rehabilitation training of community-dwelling stroke survivors could focus on walking endurance, balance performance and dorsiflexor muscle strengthening if the aim is to augment the level of community integration.

  19. A question of balance: Kinetic balance for electrons and positrons

    International Nuclear Information System (INIS)

    Dyall, Kenneth G.

    2012-01-01

    Graphical abstract: Kinetic balance for both electrons and positrons is achieved by applying the correct relation for positive and negative energy states separately and then using the electron and positron eigensolutions from the separate diagonalizations of the Hamiltonian as a dual basis. Highlights: ► Kinetic balance for electrons and positrons is achieved in a dual atomic basis. ► Dual atomic balance alleviates, but does not eliminate, energy prolapse. ► Positron affinities converge quicker with basis set size with dual atomic balance. - Abstract: The kinetic balance criterion used in current relativistic basis set codes is satisfied by the electron solutions of the Dirac equation, but not the positron solutions. A proposal for applying kinetic balance to both sets of solutions is presented. The method is applied along with “normal” kinetic balance to one-electron systems, to investigate its possible relation to prolapse, and to the positron affinity of F − , to investigate the kinetic energy deficiency for positron solutions. The new method reduces but does not eliminate prolapse for energy-optimized basis sets, and provides faster and smoother convergence with basis set size for the positron affinity.

  20. A January angular momentum balance in the OSU two-level atmospheric general circulation model

    Science.gov (United States)

    Kim, J.-W.; Grady, W.

    1982-01-01

    The present investigation is concerned with an analysis of the atmospheric angular momentum balance, based on the simulation data of the Oregon State University two-level atmospheric general circulation model (AGCM). An attempt is also made to gain an understanding of the involved processes. Preliminary results on the angular momentum and mass balance in the AGCM are shown. The basic equations are examined, and questions of turbulent momentum transfer are investigated. The methods of analysis are discussed, taking into account time-averaged balance equations, time and longitude-averaged balance equations, mean meridional circulation, the mean meridional balance of relative angular momentum, and standing and transient components of motion.

  1. The Relationship Between Pedometer-Determined Ambulatory Activity and Balance Variables Within an Older Adult Population.

    Science.gov (United States)

    Campbell, Candice; Kress, Jeff; Schroeder, Jan; Donlin, Ayla; Rozenek, Ralph

    2016-01-01

    The purpose of this investigation was to determine the differences between gender, physical activity level, and balance in an older adult population. A secondary purpose was to examine the relationship between pedometer-determined ambulatory activity and balance. Forty-six older adults aged 73.7 ± 6.2 years participated in the study. Participants completed the Fullerton Advanced Balance (FAB) Scale and completed a 2-week daily step recording to determine average steps taken per day. Low-level activity participants (7,500 steps/day) in weight, age, and the number of medications reported. Males performed better than females on the two-footed jump test and reactive postural test FAB assessments. High-level activity participants performed significantly better than low-level activity participants on all FAB assessments except stand with feet together and eyes closed, reach forward to object, and walk with head turns.

  2. Towards a theory of cortical columns: From spiking neurons to interacting neural populations of finite size.

    Science.gov (United States)

    Schwalger, Tilo; Deger, Moritz; Gerstner, Wulfram

    2017-04-01

    Neural population equations such as neural mass or field models are widely used to study brain activity on a large scale. However, the relation of these models to the properties of single neurons is unclear. Here we derive an equation for several interacting populations at the mesoscopic scale starting from a microscopic model of randomly connected generalized integrate-and-fire neuron models. Each population consists of 50-2000 neurons of the same type but different populations account for different neuron types. The stochastic population equations that we find reveal how spike-history effects in single-neuron dynamics such as refractoriness and adaptation interact with finite-size fluctuations on the population level. Efficient integration of the stochastic mesoscopic equations reproduces the statistical behavior of the population activities obtained from microscopic simulations of a full spiking neural network model. The theory describes nonlinear emergent dynamics such as finite-size-induced stochastic transitions in multistable networks and synchronization in balanced networks of excitatory and inhibitory neurons. The mesoscopic equations are employed to rapidly integrate a model of a cortical microcircuit consisting of eight neuron types, which allows us to predict spontaneous population activities as well as evoked responses to thalamic input. Our theory establishes a general framework for modeling finite-size neural population dynamics based on single cell and synapse parameters and offers an efficient approach to analyzing cortical circuits and computations.

  3. Application of heat-balance integral method to conjugate thermal explosion

    Directory of Open Access Journals (Sweden)

    Novozhilov Vasily

    2009-01-01

    Full Text Available Conjugate thermal explosion is an extension of the classical theory, proposed and studied recently by the author. The paper reports application of heat-balance integral method for developing phase portraits for systems undergoing conjugate thermal explosion. The heat-balance integral method is used as an averaging method reducing partical differential equation problem to the set of first-order ordinary differential equations. The latter reduced problem allows natural interpretation in appropriately chosen phase space. It is shown that, with the help of heat-balance integral technique, conjugate thermal explosion problem can be described with a good accuracy by the set of non-linear first-order differential equations involving complex error function. Phase trajectories are presented for typical regimes emerging in conjugate thermal explosion. Use of heat-balance integral as a spatial averaging method allows efficient description of system evolution to be developed.

  4. Accuracy of an equation for estimating age from mandibular third molar development in a Thai population

    Energy Technology Data Exchange (ETDEWEB)

    Verochana, Karune; Prapayasatok, Sangsom; Janhom, Apirum; Mahasantipiya, Phattaranant May; Korwanich, Narumanas [Faculty of Dentistry, Chiang Mai University, Chiang Mai (Thailand)

    2016-03-15

    This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

  5. Accuracy of an equation for estimating age from mandibular third molar development in a Thai population

    International Nuclear Information System (INIS)

    Verochana, Karune; Prapayasatok, Sangsom; Janhom, Apirum; Mahasantipiya, Phattaranant May; Korwanich, Narumanas

    2016-01-01

    This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age

  6. Accuracy of an equation for estimating age from mandibular third molar development in a Thai population.

    Science.gov (United States)

    Verochana, Karune; Prapayasatok, Sangsom; Janhom, Apirum; Mahasantipiya, Phattaranant May; Korwanich, Narumanas

    2016-03-01

    This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

  7. Eulerian Multiphase Population Balance Model of Atomizing, Swirling Flows

    Directory of Open Access Journals (Sweden)

    Narayana P. Rayapati

    2011-06-01

    Full Text Available An Eulerian/Eulerian multiphase flow model coupled with a population balance model is used as the basis for numerical simulation of atomization in swirling flows. The objective of this exercise is to develop a methodology capable of predicting the local point-wise drop size distribution in a spray, such as would be measured by the Phase Doppler Particle Analyzer (PDA. Model predictions are compared to experimental measurements of particle size distributions in an air-blast atomizer spray to demonstrate good qualitative and quantitative agreement. It is observed that the dependence of velocity on drop size inherent in a multiphase description of the drop cloud appears necessary to capture some features of the experimental data. Using this model, we demonstrate the relative contributions of secondary atomization and transport to the variation observed in the downstream spray drop size distribution.

  8. The Relationship Between Pedometer-Determined Ambulatory Activity and Balance Variables Within an Older Adult Population

    Directory of Open Access Journals (Sweden)

    Candice Campbell MS

    2016-12-01

    Full Text Available The purpose of this investigation was to determine the differences between gender, physical activity level, and balance in an older adult population. A secondary purpose was to examine the relationship between pedometer-determined ambulatory activity and balance. Forty-six older adults aged 73.7 ± 6.2 years participated in the study. Participants completed the Fullerton Advanced Balance (FAB Scale and completed a 2-week daily step recording to determine average steps taken per day. Low-level activity participants (7,500 steps/day in weight, age, and the number of medications reported. Males performed better than females on the two-footed jump test and reactive postural test FAB assessments. High-level activity participants performed significantly better than low-level activity participants on all FAB assessments except stand with feet together and eyes closed, reach forward to object, and walk with head turns.

  9. A Markov model for the temporal dynamics of balanced random networks of finite size

    Science.gov (United States)

    Lagzi, Fereshteh; Rotter, Stefan

    2014-01-01

    The balanced state of recurrent networks of excitatory and inhibitory spiking neurons is characterized by fluctuations of population activity about an attractive fixed point. Numerical simulations show that these dynamics are essentially nonlinear, and the intrinsic noise (self-generated fluctuations) in networks of finite size is state-dependent. Therefore, stochastic differential equations with additive noise of fixed amplitude cannot provide an adequate description of the stochastic dynamics. The noise model should, rather, result from a self-consistent description of the network dynamics. Here, we consider a two-state Markovian neuron model, where spikes correspond to transitions from the active state to the refractory state. Excitatory and inhibitory input to this neuron affects the transition rates between the two states. The corresponding nonlinear dependencies can be identified directly from numerical simulations of networks of leaky integrate-and-fire neurons, discretized at a time resolution in the sub-millisecond range. Deterministic mean-field equations, and a noise component that depends on the dynamic state of the network, are obtained from this model. The resulting stochastic model reflects the behavior observed in numerical simulations quite well, irrespective of the size of the network. In particular, a strong temporal correlation between the two populations, a hallmark of the balanced state in random recurrent networks, are well represented by our model. Numerical simulations of such networks show that a log-normal distribution of short-term spike counts is a property of balanced random networks with fixed in-degree that has not been considered before, and our model shares this statistical property. Furthermore, the reconstruction of the flow from simulated time series suggests that the mean-field dynamics of finite-size networks are essentially of Wilson-Cowan type. We expect that this novel nonlinear stochastic model of the interaction between

  10. Cognitive Load in Algebra: Element Interactivity in Solving Equations

    Science.gov (United States)

    Ngu, Bing Hiong; Chung, Siu Fung; Yeung, Alexander Seeshing

    2015-01-01

    Central to equation solving is the maintenance of equivalence on both sides of the equation. However, when the process involves an interaction of multiple elements, solving an equation can impose a high cognitive load. The balance method requires operations on both sides of the equation, whereas the inverse method involves operations on one side…

  11. The effect of hitch-hiking on genes linked to a balanced polymorphism in a subdivided population

    DEFF Research Database (Denmark)

    Schierup, M H; Charlesworth, D; Vekemans, X

    2000-01-01

    types of subdivision are present: (1) into demes (connected by migration), and (2) into classes defined by different functional alleles at the selected locus (connected by recombination). Previous theoretical studies of each type of subdivision separately have shown that each increases diversity...... to detect balancing selection by its effects on linked variation, using tests such as Tajima's D, is reduced when genes in a subdivided population are sampled from the total population, rather than within demes. Udgivelsesdato: 2000-Aug...

  12. Equations governing the liquid-film flow over a plane with heat flux and interfacial phase change

    International Nuclear Information System (INIS)

    Spindler, B.

    1983-01-01

    The purpose of the study is to find a system of equations which can be used to study the linear stability of a liquid film flow over a plane exhibiting wall heat flux and interfacial phase change. The flow of such a film is governed by four groups of equations: the equations for mass balance, momentum and energy in the liquid; equations for the balance in the steam; equations for the balance at the liquid-steam interface; and the boundary conditions. Two flow patterns are considered - flow with upstream film and film condensation. Stability is studied by perturbation methods

  13. Equations governing the liquid-film flow over a plane with heat flux and interfacial phase change

    Science.gov (United States)

    Spindler, B.

    1983-08-01

    The purpose of the study is to find a system of equations which can be used to study the linear stability of a liquid film flow over a plane exhibiting wall heat flux and interfacial phase change. The flow of such a film is governed by four groups of equations: the equations for mass balance, momentum and energy in the liquid; equations for the balance in the steam; equations for the balance at the liquid-steam interface; and the boundary conditions. Two flow patterns are considered - flow with upstream film and film condensation. Stability is studied by perturbation methods.

  14. Solutions manual to accompany Ordinary differential equations

    CERN Document Server

    Greenberg, Michael D

    2014-01-01

    Features a balance between theory, proofs, and examples and provides applications across diverse fields of study Ordinary Differential Equations presents a thorough discussion of first-order differential equations and progresses to equations of higher order. The book transitions smoothly from first-order to higher-order equations, allowing readers to develop a complete understanding of the related theory. Featuring diverse and interesting applications from engineering, bioengineering, ecology, and biology, the book anticipates potential difficulties in understanding the various solution steps

  15. Using fundamental equations to describe basic phenomena

    DEFF Research Database (Denmark)

    Jakobsen, Arne; Rasmussen, Bjarne D.

    1999-01-01

    When the fundamental thermodynamic balance equations (mass, energy, and momentum) are used to describe the processes in a simple refrigeration system, then one finds that the resulting equation system will have a degree of freedom equal to one. Further investigations reveal that it is the equatio...

  16. Fractional hydrodynamic equations for fractal media

    International Nuclear Information System (INIS)

    Tarasov, Vasily E.

    2005-01-01

    We use the fractional integrals in order to describe dynamical processes in the fractal medium. We consider the 'fractional' continuous medium model for the fractal media and derive the fractional generalization of the equations of balance of mass density, momentum density, and internal energy. The fractional generalization of Navier-Stokes and Euler equations are considered. We derive the equilibrium equation for fractal media. The sound waves in the continuous medium model for fractional media are considered

  17. Validation of predictive equations for glomerular filtration rate in the Saudi population

    Directory of Open Access Journals (Sweden)

    Al Wakeel Jamal

    2009-01-01

    Full Text Available Predictive equations provide a rapid method of assessing glomerular filtration rate (GFR. To compare the various predictive equations for the measurement of this parameter in the Saudi population, we measured GFR by the Modification of Diet in Renal Disease (MDRD and Cockcroft-Gault formulas, cystatin C, reciprocal of cystatin C, creatinine clearance, reciprocal of creatinine, and inulin clearance in 32 Saudi subjects with different stages of renal disease. We com-pared GFR measured by inulin clearance and the estimated GFR by the equations. The study included 19 males (59.4% and 13 (40.6% females with a mean age of 42.3 ± 15.2 years and weight of 68.6 ± 17.7 kg. The mean serum creatinine was 199 ± 161 μmol/L. The GFR measured by inulin clearance was 50.9 ± 33.5 mL/min, and the estimated by Cockcroft-Gault and by MDRD equations was 56.3 ± 33.3 and 52.8 ± 32.0 mL/min, respectively. The GFR estimated by MDRD revealed the strongest correlation with the measured inulin clearance (r= 0.976, P= 0.0000 followed by the GFR estimated by Cockcroft-Gault, serum cystatin C, and serum creatinine (r= 0.953, P= 0.0000 (r= 0.787, P= 0.0001 (r= -0.678, P= 0.001, respectively. The reciprocal of cystatin C and serum creatinine revealed a correlation coefficient of 0.826 and 0.93, respectively. Cockroft-Gault for-mula overestimated the GFR by 5.40 ± 10.3 mL/min in comparison to the MDRD formula, which exhibited the best correlation with inulin clearance in different genders, age groups, body mass index, renal transplant recipients, chronic kidney disease stages when compared to other GFR predictive equations.

  18. Towards a theory of cortical columns: From spiking neurons to interacting neural populations of finite size

    Science.gov (United States)

    Gerstner, Wulfram

    2017-01-01

    Neural population equations such as neural mass or field models are widely used to study brain activity on a large scale. However, the relation of these models to the properties of single neurons is unclear. Here we derive an equation for several interacting populations at the mesoscopic scale starting from a microscopic model of randomly connected generalized integrate-and-fire neuron models. Each population consists of 50–2000 neurons of the same type but different populations account for different neuron types. The stochastic population equations that we find reveal how spike-history effects in single-neuron dynamics such as refractoriness and adaptation interact with finite-size fluctuations on the population level. Efficient integration of the stochastic mesoscopic equations reproduces the statistical behavior of the population activities obtained from microscopic simulations of a full spiking neural network model. The theory describes nonlinear emergent dynamics such as finite-size-induced stochastic transitions in multistable networks and synchronization in balanced networks of excitatory and inhibitory neurons. The mesoscopic equations are employed to rapidly integrate a model of a cortical microcircuit consisting of eight neuron types, which allows us to predict spontaneous population activities as well as evoked responses to thalamic input. Our theory establishes a general framework for modeling finite-size neural population dynamics based on single cell and synapse parameters and offers an efficient approach to analyzing cortical circuits and computations. PMID:28422957

  19. Extension of the method of moments for population balances involving fractional moments and application to a typical agglomeration problem.

    Science.gov (United States)

    Alexiadis, Alessio; Vanni, Marco; Gardin, Pascal

    2004-08-01

    The method of moment (MOM) is a powerful tool for solving population balance. Nevertheless it cannot be used in every circumstance. Sometimes, in fact, it is not possible to write the governing equations in closed form. Higher moments, for instance, could appear in the evolution of the lower ones. This obstacle has often been resolved by prescribing some functional form for the particle size distribution. Another example is the occurrence of fractional moment, usually connected with the presence of fractal aggregates. For this case we propose a procedure that does not need any assumption on the form of the distribution but it is based on the "moments generating function" (that is the Laplace transform of the distribution). An important result of probability theory is that the kth derivative of the moments generating function represents the kth moment of the original distribution. This result concerns integer moments but, taking in account the Weyl fractional derivative, could be extended to fractional orders. Approximating fractional derivative makes it possible to express the fractional moments in terms of the integer ones and so to use regularly the method of moments.

  20. Exact solutions to two higher order nonlinear Schroedinger equations

    International Nuclear Information System (INIS)

    Xu Liping; Zhang Jinliang

    2007-01-01

    Using the homogeneous balance principle and F-expansion method, the exact solutions to two higher order nonlinear Schroedinger equations which describe the propagation of femtosecond pulses in nonlinear fibres are obtained with the aid of a set of subsidiary higher order ordinary differential equations (sub-equations for short)

  1. Balancing selection and heterogeneity across the classical human leukocyte antigen loci: a meta-analytic review of 497 population studies.

    Science.gov (United States)

    Solberg, Owen D; Mack, Steven J; Lancaster, Alex K; Single, Richard M; Tsai, Yingssu; Sanchez-Mazas, Alicia; Thomson, Glenys

    2008-07-01

    This paper presents a meta-analysis of high-resolution human leukocyte antigen (HLA) allele frequency data describing 497 population samples. Most of the datasets were compiled from studies published in eight journals from 1990 to 2007; additional datasets came from the International Histocompatibility Workshops and from the AlleleFrequencies.net database. In all, these data represent approximately 66,800 individuals from throughout the world, providing an opportunity to observe trends that may not have been evident at the time the data were originally analyzed, especially with regard to the relative importance of balancing selection among the HLA loci. Population genetic measures of allele frequency distributions were summarized across populations by locus and geographic region. A role for balancing selection maintaining much of HLA variation was confirmed. Further, the breadth of this meta-analysis allowed the ranking of the HLA loci, with DQA1 and HLA-C showing the strongest balancing selection and DPB1 being compatible with neutrality. Comparisons of the allelic spectra reported by studies since 1990 indicate that most of the HLA alleles identified since 2000 are very-low-frequency alleles. The literature-based allele-count data, as well as maps summarizing the geographic distributions for each allele, are available online.

  2. dimensional nonlinear evolution equations

    Indian Academy of Sciences (India)

    in real-life situations, it is important to find their exact solutions. Further, in ... But only little work is done on the high-dimensional equations. .... Similarly, to determine the values of d and q, we balance the linear term of the lowest order in eq.

  3. A sensitivity analysis of the mass balance equation terms in subcooled flow boiling

    International Nuclear Information System (INIS)

    Braz Filho, Francisco A.; Caldeira, Alexandre D.; Borges, Eduardo M.

    2013-01-01

    In a heated vertical channel, the subcooled flow boiling occurs when the fluid temperature reaches the saturation point, actually a small overheating, near the channel wall while the bulk fluid temperature is below this point. In this case, vapor bubbles are generated along the channel resulting in a significant increase in the heat flux between the wall and the fluid. This study is particularly important to the thermal-hydraulics analysis of Pressurized Water Reactors (PWRs). The computational fluid dynamics software FLUENT uses the Eulerian multiphase model to analyze the subcooled flow boiling. In a previous paper, the comparison of the FLUENT results with experimental data for the void fraction presented a good agreement, both at the beginning of boiling as in nucleate boiling at the end of the channel. In the region between these two points the comparison with experimental data was not so good. Thus, a sensitivity analysis of the mass balance equation terms, steam production and condensation, was performed. Factors applied to the terms mentioned above can improve the agreement of the FLUENT results to the experimental data. Void fraction calculations show satisfactory results in relation to the experimental data in pressures values of 15, 30 and 45 bars. (author)

  4. Extended irreversible thermodynamics and the Jeffreys type constitutive equations

    International Nuclear Information System (INIS)

    Serdyukov, S.I.

    2003-01-01

    A postulate of extended irreversible thermodynamics is considered, according to which the entropy density is a function of the internal energy, the specific volume, and their material time derivatives. On the basis of this postulate, entropy balance equations and phenomenological equations are obtained, which directly lead to the Jeffreys type constitutive equations

  5. The nuclear flow and the mass number dependence of the balance point

    International Nuclear Information System (INIS)

    Sebille, F.; de la Mota, V.; Remaud, B.; Schuck, P.

    1990-01-01

    The nuclear flow is studied theoretically with the Landau Vlasov equation in the E/A = 50 to 150 MeV energy domain using the finite range Gogny force. For comparison also other equations of states based on velocity independent mean fields are used. In this paper the mass number dependence of the balance point is investigated. A sensitivity of the flow on the equation of state as a function of mass and energies around and above the balance point can tentatively be advanced

  6. Diagnostic and correction of chronic-biological mis-balances of population at radiation injuries in regions with increased radiation

    International Nuclear Information System (INIS)

    Goncharova, T.G.; Vasil'eva, G.S.

    2003-01-01

    It was shown the possibility of bio-indication of population irradiation and its rehabilitation by estimation of chronic biological mis-balances and correction realization. Investigation were accomplished on people contingent living at the former Semipalatinsk test site

  7. Frequency interval balanced truncation of discrete-time bilinear systems

    DEFF Research Database (Denmark)

    Jazlan, Ahmad; Sreeram, Victor; Shaker, Hamid Reza

    2016-01-01

    This paper presents the development of a new model reduction method for discrete-time bilinear systems based on the balanced truncation framework. In many model reduction applications, it is advantageous to analyze the characteristics of the system with emphasis on particular frequency intervals...... are the solution to a pair of new generalized Lyapunov equations. The conditions for solvability of these new generalized Lyapunov equations are derived and a numerical solution method for solving these generalized Lyapunov equations is presented. Numerical examples which illustrate the usage of the new...... generalized frequency interval controllability and observability gramians as part of the balanced truncation framework are provided to demonstrate the performance of the proposed method....

  8. Equations of motion for a (non-linear) scalar field model as derived from the field equations

    International Nuclear Information System (INIS)

    Kaniel, S.; Itin, Y.

    2006-01-01

    The problem of derivation of the equations of motion from the field equations is considered. Einstein's field equations have a specific analytical form: They are linear in the second order derivatives and quadratic in the first order derivatives of the field variables. We utilize this particular form and propose a novel algorithm for the derivation of the equations of motion from the field equations. It is based on the condition of the balance between the singular terms of the field equation. We apply the algorithm to a non-linear Lorentz invariant scalar field model. We show that it results in the Newton law of attraction between the singularities of the field moved on approximately geodesic curves. The algorithm is applicable to the N-body problem of the Lorentz invariant field equations. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  9. Algebraic quantity equations before Fisher and Pigou

    OpenAIRE

    Thomas M. Humphrey

    1984-01-01

    Readers of this Review are doubtlessly familiar with the famous equation of exchange, MV=PQ, frequently employed to analyze the price level effects of monetary shocks. One might think the algebraic formulation of the equation is an outgrowth of the 20th century tendency toward mathematical modeling and statistical testing. Indeed, textbooks typically associate the transaction velocity version of the equation with Irving Fisher and the alternative Cambridge cash balance version with A. C. Pigo...

  10. Changes of the calculation equation for σMUF

    International Nuclear Information System (INIS)

    Yoshida, Hideki; Niiyama, Toshitaka; Sonobe, Kentaro

    2002-01-01

    The error variance (σ MUF 2 ) of the material accountancy for the material balance is used for evaluating the MUF of the conventional material accountancy and the near real time material accountancy (NRTA). The σ MUF 2 calculated by the error propagation using the material accounting data and the measurement error. The error propagation equation of σ MUF 2 written on the text of 'The statistical concepts and technique for IAEA safeguards (IAEA/SG/SCT5)'. There are some assumptions in order to simplify the equation. These assumptions are available in the assessment of the facility design. However when the σ MUF 2 of the actual MUF is calculated, it is necessary to drop some assumptions and modify the adapted equation. Furthermore, because the material balance is more frequently taken for NRTA, the inventory of all times cannot be always re-measured at each time. To be solved the matter, the error propagation equation has to be modified. For a reprocessing plant which has material in solution, the equation has been improved to obtain more exact equation. In this paper we present the changes of the error propagation for σ MUF 2 and explain the features. (author)

  11. Numerical Analysis of Partial Differential Equations

    CERN Document Server

    Lui, S H

    2011-01-01

    A balanced guide to the essential techniques for solving elliptic partial differential equations Numerical Analysis of Partial Differential Equations provides a comprehensive, self-contained treatment of the quantitative methods used to solve elliptic partial differential equations (PDEs), with a focus on the efficiency as well as the error of the presented methods. The author utilizes coverage of theoretical PDEs, along with the nu merical solution of linear systems and various examples and exercises, to supply readers with an introduction to the essential concepts in the numerical analysis

  12. Evolutionary game theory for physical and biological scientists. I. Training and validating population dynamics equations.

    Science.gov (United States)

    Liao, David; Tlsty, Thea D

    2014-08-06

    Failure to understand evolutionary dynamics has been hypothesized as limiting our ability to control biological systems. An increasing awareness of similarities between macroscopic ecosystems and cellular tissues has inspired optimism that game theory will provide insights into the progression and control of cancer. To realize this potential, the ability to compare game theoretic models and experimental measurements of population dynamics should be broadly disseminated. In this tutorial, we present an analysis method that can be used to train parameters in game theoretic dynamics equations, used to validate the resulting equations, and used to make predictions to challenge these equations and to design treatment strategies. The data analysis techniques in this tutorial are adapted from the analysis of reaction kinetics using the method of initial rates taught in undergraduate general chemistry courses. Reliance on computer programming is avoided to encourage the adoption of these methods as routine bench activities.

  13. The population and decay evolution of a qubit under the time-convolutionless master equation

    International Nuclear Information System (INIS)

    Huang Jiang; Fang Mao-Fa; Liu Xiang

    2012-01-01

    We consider the population and decay of a qubit under the electromagnetic environment. Employing the time-convolutionless master equation, we investigate the Markovian and non-Markovian behaviour of the corresponding perturbation expansion. The Jaynes-Cummings model on resonance is investigated. Some figures clearly show the different evolution behaviours. The reasons are interpreted in the paper. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  14. Balance Systems and the Variational Bicomplex

    Directory of Open Access Journals (Sweden)

    Serge Preston

    2011-07-01

    Full Text Available In this work we show that the systems of balance equations (balance systems of continuum thermodynamics occupy a natural place in the variational bicomplex formalism. We apply the vertical homotopy decomposition to get a local splitting (in a convenient domain of a general balance system as the sum of a Lagrangian part and a complemental ''pure non-Lagrangian'' balance system. In the case when derivatives of the dynamical fields do not enter the constitutive relations of the balance system, the ''pure non-Lagrangian'' systems coincide with the systems introduced by S. Godunov [Soviet Math. Dokl. 2 (1961, 947-948] and, later, asserted as the canonical hyperbolic form of balance systems in [Müller I., Ruggeri T., Rational extended thermodynamics, 2nd ed., Springer Tracts in Natural Philosophy, Vol. 37, Springer-Verlag, New York, 1998].

  15. Exact solutions to a class of nonlinear Schrödinger-type equations

    Indian Academy of Sciences (India)

    A class of nonlinear Schrödinger-type equations, including the Rangwala–Rao equation, the Gerdjikov–Ivanov equation, the Chen–Lee–Lin equation and the Ablowitz–Ramani–Segur equation are investigated, and the exact solutions are derived with the aid of the homogeneous balance principle, and a set of subsidiary ...

  16. Balanced Hermitian metrics from SU(2)-structures

    International Nuclear Information System (INIS)

    Fernandez, M.; Tomassini, A.; Ugarte, L.; Villacampa, R.

    2009-01-01

    We study the intrinsic geometrical structure of hypersurfaces in six-manifolds carrying a balanced Hermitian SU(3)-structure, which we call balanced SU(2)-structure. We provide sufficient conditions, in terms of suitable evolution equations, which imply that a five-manifold with such structure can be isometrically embedded as a hypersurface in a balanced Hermitian SU(3)-manifold. Any five-dimensional compact nilmanifold has an invariant balanced SU(2)-structure, and we show how some of them can be evolved to give new explicit examples of balanced Hermitian SU(3)-structures. Moreover, for n=3,4, we present examples of compact solvmanifolds endowed with a balanced SU(n)-structure such that the corresponding Bismut connection has holonomy equal to SU(n)

  17. Validity of a population-specific BMR predictive equation for adults from an urban tropical setting.

    Science.gov (United States)

    Wahrlich, Vivian; Teixeira, Tatiana Miliante; Anjos, Luiz Antonio Dos

    2018-02-01

    Basal metabolic rate (BMR) is an important physiologic measure in nutrition research. In many instances it is not measured but estimated by predictive equations. The purpose of this study was to compare measured BMR (BMRm) with estimated BMR (BMRe) obtained by different equations. A convenient sample of 148 (89 women) 20-60 year-old subjects from the metropolitan area of Rio de Janeiro, Brazil participated in the study. BMRm values were measured by an indirect calorimeter and predicted by different equations (Schofield, Henry and Rees, Mifflin-St. Jeor and Anjos. All subjects had their body composition and anthropometric variables also measured. Accuracy of the estimations was established by the percentage of BMRe falling within ±10% of BMRm and bias when the 95% CI of the difference of BMRe and BMRm means did not include zero. Mean BMRm values were 4833.5 (SD 583.3) and 6278.8 (SD 724.0) kJ*day -1 for women and men, respectively. BMRe values were both biased and inaccurate except for values predicted by the Anjos equation. BMR overestimation was approximately 20% for the Schofield equation which was higher comparatively to the Henry and Rees (14.5% and 9.6% for women and men, respectively) and the Mifflin-St. Jeor (approximately 14.0%) equations. BMR estimated by the Anjos equation was unbiased (95% CI = -78.1; 96.3 kJ day -1 for women and -282.6; 30.7 kJ*day -1 for men). Population-specific BMR predictive equations yield unbiased and accurate BMR values in adults from an urban tropical setting. Copyright © 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  18. Diagnosis of balanced and unbalanced motions in a synoptic-scale baroclinic wave life cycle

    International Nuclear Information System (INIS)

    Bush, A.B.G.; Peltier, W.R.; McWilliams, J.C.

    1994-01-01

    For numerical simulations of large scale dynamics, balanced models are attractive because their governing equations preclude gravity waves and one is thereby free to use a larger time step than is possible with a model governed by the primitive equations. Recent comparative studies have proven the so-called balance equations to be the most accurate of the intermediate models. In this particular study, a new set of balance equations is derived for a three-dimensional anelastic primitive equation simulation of a synoptic-scale baroclinic wave. Results indicate that both forms of imbalance. slow higher-order corrections and fast gravity wave motions, arise in the simulation. Investigations into the origin of these gravity waves reveal that the frontal slope near the time of occlusion decreases in the lower 2 kilometers to a value beyond compatability with the vertical and horizontal resolution employed, and we conclude that the waves are numerically generated

  19. Balance Assessment Practices and Use of Standardized Balance Measures Among Ontario Physical Therapists

    Science.gov (United States)

    Sibley, Kathryn M.; Straus, Sharon E.; Inness, Elizabeth L.; Salbach, Nancy M.

    2011-01-01

    Background Balance impairment is a significant problem for older adults, as it can influence daily functioning. Treating balance impairment in this population is a major focus of physical therapist practice. Objective The purpose of this study was to document current practices in clinical balance assessment and compare components of balance assessed and measures used across practice areas among physical therapists. Design This was a cross-sectional study. Methods A survey questionnaire was mailed to 1,000 practicing physical therapists in Ontario, Canada. Results Three hundred sixty-nine individuals completed the survey questionnaire. More than 80% of respondents reported that they regularly (more than 60% of the time) assessed postural alignment, static and dynamic stability, functional balance, and underlying motor systems. Underlying sensory systems, cognitive contributions to balance, and reactive control were regularly assessed by 59.6%, 55.0%, and 41.2% of the respondents, respectively. The standardized measures regularly used by the most respondents were the single-leg stance test (79.1%), the Berg Balance Scale (45.0%), and the Timed “Up & Go” Test (27.6%). There was considerable variation in the components of balance assessed and measures used by respondents treating individuals in the orthopedic, neurologic, geriatric, and general rehabilitation populations. Limitations The survey provides quantitative data about what is done to assess balance, but does not explain the factors influencing current practice. Conclusions Many important components of balance and standardized measures are regularly used by physical therapists to assess balance. Further research, however, is needed to understand the factors contributing to the relatively lower rates of assessing reactive control, the component of balance most directly responsible for avoiding a fall. PMID:21868613

  20. Reference population equations using peak expiratory flow meters ...

    African Journals Online (AJOL)

    Many formulae for predicting lung function values for Nigerians have been produced by a lot of investigators. The same principle but different statistical methods were adopted by different authors in generating these equations, hence the variability observed among these formulae. Most equations in current use are based on ...

  1. The physics behind Van der Burgh's empirical equation, providing a new predictive equation for salinity intrusion in estuaries

    Science.gov (United States)

    Zhang, Zhilin; Savenije, Hubert H. G.

    2017-07-01

    The practical value of the surprisingly simple Van der Burgh equation in predicting saline water intrusion in alluvial estuaries is well documented, but the physical foundation of the equation is still weak. In this paper we provide a connection between the empirical equation and the theoretical literature, leading to a theoretical range of Van der Burgh's coefficient of 1/2 residual circulation. This type of mixing is relevant in the wider part of alluvial estuaries where preferential ebb and flood channels appear. Subsequently, this dispersion equation is combined with the salt balance equation to obtain a new predictive analytical equation for the longitudinal salinity distribution. Finally, the new equation was tested and applied to a large database of observations in alluvial estuaries, whereby the calibrated K values appeared to correspond well to the theoretical range.

  2. Integrodifference equations in patchy landscapes : II: population level consequences.

    Science.gov (United States)

    Musgrave, Jeffrey; Lutscher, Frithjof

    2014-09-01

    We analyze integrodifference equations (IDEs) in patchy landscapes. Movement is described by a dispersal kernel that arises from a random walk model with patch dependent diffusion, settling, and mortality rates, and it incorporates individual behavior at an interface between two patch types. Growth follows a simple Beverton-Holt growth or linear decay. We obtain explicit formulae for the critical domain-size problem, and we illustrate how different individual behavior at the boundary between two patch types affects this quantity. We also study persistence conditions on an infinite, periodic, patchy landscape. We observe that if the population can persist on the landscape, the spatial profile of the invasion evolves into a discontinuous traveling periodic wave that moves with constant speed. Assuming linear determinacy, we calculate the dispersion relation and illustrate how movement behavior affects invasion speed. Numerical simulations justify our approach by showing a close correspondence between the spread rate obtained from the dispersion relation and from numerical simulations.

  3. Generalized large-scale semigeostrophic approximations for the f-plane primitive equations

    Science.gov (United States)

    Oliver, Marcel; Vasylkevych, Sergiy

    2016-05-01

    We derive a family of balance models for rotating stratified flow in the primitive equation (PE) setting. By construction, the models possess conservation laws for energy and potential vorticity and are formally of the same order of accuracy as Hoskins’ semigeostrophic equations. Our construction is based on choosing a new coordinate frame for the PE variational principle in such a way that the consistently truncated Lagrangian degenerates. We show that the balance relations so obtained are elliptic when the fluid is stably stratified and certain smallness assumptions are satisfied. Moreover, the potential temperature can be recovered from the potential vorticity via inversion of a non-standard Monge-Ampère problem which is subject to the same ellipticity condition. While the present work is entirely formal, we conjecture, based on a careful rewriting of the equations of motion and a straightforward derivative count, that the Cauchy problem for the balance models is well posed subject to conditions on the initial data. Our family of models includes, in particular, the stratified analog of the L 1 balance model of Salmon.

  4. Generalized large-scale semigeostrophic approximations for the f-plane primitive equations

    International Nuclear Information System (INIS)

    Oliver, Marcel; Vasylkevych, Sergiy

    2016-01-01

    We derive a family of balance models for rotating stratified flow in the primitive equation (PE) setting. By construction, the models possess conservation laws for energy and potential vorticity and are formally of the same order of accuracy as Hoskins’ semigeostrophic equations. Our construction is based on choosing a new coordinate frame for the PE variational principle in such a way that the consistently truncated Lagrangian degenerates. We show that the balance relations so obtained are elliptic when the fluid is stably stratified and certain smallness assumptions are satisfied. Moreover, the potential temperature can be recovered from the potential vorticity via inversion of a non-standard Monge–Ampère problem which is subject to the same ellipticity condition. While the present work is entirely formal, we conjecture, based on a careful rewriting of the equations of motion and a straightforward derivative count, that the Cauchy problem for the balance models is well posed subject to conditions on the initial data. Our family of models includes, in particular, the stratified analog of the L 1 balance model of Salmon. (paper)

  5. On the evolution of perturbations to solutions of the Kadomtsev-Petviashvilli equation using the Benney-Luke equation

    International Nuclear Information System (INIS)

    Ablowitz, Mark J; Curtis, Christopher W

    2011-01-01

    The Benney-Luke equation, which arises as a long wave asymptotic approximation of water waves, contains the Kadomtsev-Petviashvilli (KP) equation as a leading-order maximal balanced approximation. The question analyzed is how the Benney-Luke equation modifies the so-called web solutions of the KP equation. It is found that the Benney-Luke equation introduces dispersive radiation which breaks each of the symmetric soliton-like humps well away from the interaction region of the KP web solution into a tail of multi-peaked oscillating profiles behind the main solitary hump. Computation indicates that the wave structure is modified near the center of the interaction region. Both analytical and numerical techniques are employed for working with non-periodic, non-decaying solutions on unbounded domains.

  6. On the evolution of perturbations to solutions of the Kadomtsev-Petviashvilli equation using the Benney-Luke equation

    Science.gov (United States)

    Ablowitz, Mark J.; Curtis, Christopher W.

    2011-05-01

    The Benney-Luke equation, which arises as a long wave asymptotic approximation of water waves, contains the Kadomtsev-Petviashvilli (KP) equation as a leading-order maximal balanced approximation. The question analyzed is how the Benney-Luke equation modifies the so-called web solutions of the KP equation. It is found that the Benney-Luke equation introduces dispersive radiation which breaks each of the symmetric soliton-like humps well away from the interaction region of the KP web solution into a tail of multi-peaked oscillating profiles behind the main solitary hump. Computation indicates that the wave structure is modified near the center of the interaction region. Both analytical and numerical techniques are employed for working with non-periodic, non-decaying solutions on unbounded domains.

  7. Laminate mechanics for balanced woven fabrics

    NARCIS (Netherlands)

    Akkerman, Remko

    2006-01-01

    Laminate mechanics equations are presented for composites with balanced woven fabric reinforcements. It is shown that mimicking these textile composites with equivalent transversely isotropic (‘unidirectional’) layers requires disputable manipulations. Various micromechanics predictions of textile

  8. Effects of dynamic posturographic balance training versus conventional balance training on mobility and balance in elderly

    International Nuclear Information System (INIS)

    Saddiqi, F.A.; Masood, T.

    2017-01-01

    To determine the effects of dynamic posturographic balance training versus conventional balance training in improving mobility and balance in elderly. Methodology: Forty subjects between 50 to 80 years of age were selected via non-probability convenience sampling technique, for this randomized controlled trial. Both females and males with no major co-morbid conditions and cognitive impairments were recruited and randomized via coin toss method into two equal groups: Dynamic Posturographic balance training (DPG) group and Conventional balance training (CBT) group. The DPG training was provided via Biodex Balance System (Static and Dynamic). Both groups received interventions 3 times (35 to 45min each day) a week for 8 weeks, after which terminal assessment was done. Data were collected on demographic profile, balance via berg balance score and mobility by using Timed Up and Go Test. Independent samples t test was used to check difference between CBT group and DPG Group and repeated measures Analysis of Variance (ANOVA) was used for within-group analysis. Results: Baseline analysis of Berg balance scale and timed up and go test between two groups showed no significant difference with (p 0.805 and 0.251, respectively). After 8 weeks of intervention, there was significant difference between the groups in both variables (p 0.019 and 0.001, respectively). Conclusion: Dynamic posturographic balance training was more effective in improving dynamic balance and mobility in elderly population in comparison to conventional balance training. (author)

  9. Reliable Quantification of the Potential for Equations Based on Spot Urine Samples to Estimate Population Salt Intake

    DEFF Research Database (Denmark)

    Huang, Liping; Crino, Michelle; Wu, Jason Hy

    2016-01-01

    to a standard format. Individual participant records will be compiled and a series of analyses will be completed to: (1) compare existing equations for estimating 24-hour salt intake from spot urine samples with 24-hour urine samples, and assess the degree of bias according to key demographic and clinical......BACKGROUND: Methods based on spot urine samples (a single sample at one time-point) have been identified as a possible alternative approach to 24-hour urine samples for determining mean population salt intake. OBJECTIVE: The aim of this study is to identify a reliable method for estimating mean...... population salt intake from spot urine samples. This will be done by comparing the performance of existing equations against one other and against estimates derived from 24-hour urine samples. The effects of factors such as ethnicity, sex, age, body mass index, antihypertensive drug use, health status...

  10. Myths and methodologies: Making sense of exercise mass and water balance.

    Science.gov (United States)

    Cheuvront, Samuel N; Montain, Scott J

    2017-09-01

    What is the topic of this review? There is a need to revisit the basic principles of exercise mass and water balance, the use of common equations and the practice of interpreting outcomes. What advances does it highlight? We propose use of the following equation as a way of simplifying exercise mass and water balance calculations in conditions where food is not consumed and waste is not excreted: ∆body mass - 0.20 g/kcal -1  = ∆body water. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass - 0.20 g kcal -1 )/starting body mass] × 100. Changes in body mass occur because of flux in liquids, solids and gases. This knowledge is crucial for understanding metabolism, health and human water needs. In exercise science, corrections to observed changes in body mass to estimate water balance are inconsistently applied and often misinterpreted, particularly after prolonged exercise. Although acute body mass losses in response to exercise can represent a close surrogate for body water losses, the discordance between mass and water balance equivalence becomes increasingly inaccurate as more and more energy is expended. The purpose of this paper is briefly to clarify the roles that respiratory water loss, gas exchange and metabolic water production play in the correction of body mass changes for fluid balance determinations during prolonged exercise. Computations do not include waters of association with glycogen because any movement of water among body water compartments contributes nothing to water or mass flux from the body. Estimates of sweat loss from changes in body mass should adjust for non-sweat losses when possible. We propose use of the following equation as a way of simplifying the study of exercise mass and water balance: ∆body mass - 0.20 g kcal -1  = ∆body water. This equation directly controls for the influence of energy expenditure on body mass

  11. A Surface Temperature Initiated Closure (STIC) for surface energy balance fluxes

    DEFF Research Database (Denmark)

    Mallick, Kaniska; Jarvis, Andrew J.; Boegh, Eva

    2014-01-01

    The use of Penman–Monteith (PM) equation in thermal remote sensing based surface energy balance modeling is not prevalent due to the unavailability of any direct method to integrate thermal data into the PM equation and due to the lack of physical models expressing the surface (or stomatal......) and boundary layer conductances (gS and gB) as a function of surface temperature. Here we demonstrate a new method that physically integrates the radiometric surface temperature (TS) into the PM equation for estimating the terrestrial surface energy balance fluxes (sensible heat, H and latent heat, λ......E). The method combines satellite TS data with standard energy balance closure models in order to derive a hybrid closure that does not require the specification of surface to atmosphere conductance terms. We call this the Surface Temperature Initiated Closure (STIC), which is formed by the simultaneous solution...

  12. Resummed memory kernels in generalized system-bath master equations

    International Nuclear Information System (INIS)

    Mavros, Michael G.; Van Voorhis, Troy

    2014-01-01

    Generalized master equations provide a concise formalism for studying reduced population dynamics. Usually, these master equations require a perturbative expansion of the memory kernels governing the dynamics; in order to prevent divergences, these expansions must be resummed. Resummation techniques of perturbation series are ubiquitous in physics, but they have not been readily studied for the time-dependent memory kernels used in generalized master equations. In this paper, we present a comparison of different resummation techniques for such memory kernels up to fourth order. We study specifically the spin-boson Hamiltonian as a model system bath Hamiltonian, treating the diabatic coupling between the two states as a perturbation. A novel derivation of the fourth-order memory kernel for the spin-boson problem is presented; then, the second- and fourth-order kernels are evaluated numerically for a variety of spin-boson parameter regimes. We find that resumming the kernels through fourth order using a Padé approximant results in divergent populations in the strong electronic coupling regime due to a singularity introduced by the nature of the resummation, and thus recommend a non-divergent exponential resummation (the “Landau-Zener resummation” of previous work). The inclusion of fourth-order effects in a Landau-Zener-resummed kernel is shown to improve both the dephasing rate and the obedience of detailed balance over simpler prescriptions like the non-interacting blip approximation, showing a relatively quick convergence on the exact answer. The results suggest that including higher-order contributions to the memory kernel of a generalized master equation and performing an appropriate resummation can provide a numerically-exact solution to system-bath dynamics for a general spectral density, opening the way to a new class of methods for treating system-bath dynamics

  13. The energy balance within a bubble column evaporator

    Science.gov (United States)

    Fan, Chao; Shahid, Muhammad; Pashley, Richard M.

    2018-05-01

    Bubble column evaporator (BCE) systems have been studied and developed for many applications, such as thermal desalination, sterilization, evaporative cooling and controlled precipitation. The heat supplied from warm/hot dry bubbles is to vaporize the water in various salt solutions until the solution temperature reaches steady state, which was derived into the energy balance of the BCE. The energy balance and utilization involved in each BCE process form the fundamental theory of these applications. More importantly, it opened a new field for the thermodynamics study in the form of heat and vapor transfer in the bubbles. In this paper, the originally derived energy balance was reviewed on the basis of its physics in the BCE process and compared with new proposed energy balance equations in terms of obtained the enthalpy of vaporization (Δ H vap) values of salt solutions from BCE experiments. Based on the analysis of derivation and Δ H vap values comparison, it is demonstrated that the original balance equation has high accuracy and precision, within 2% over 19-55 °C using improved systems. Also, the experimental and theoretical techniques used for determining Δ H vap values of salt solutions were reviewed for the operation conditions and their accuracies compared to the literature data. The BCE method, as one of the most simple and accurate techniques, offers a novel way to determine Δ H vap values of salt solutions based on its energy balance equation, which had error less than 3%. The thermal energy required to heat the inlet gas, the energy used for water evaporation in the BCE and the energy conserved from water vapor condensation were estimated in an overall energy balance analysis. The good agreement observed between input and potential vapor condensation energy illustrates the efficiency of the BCE system. Typical energy consumption levels for thermal desalination for producing pure water using the BCE process was also analyzed for different inlet air

  14. A cross-national study on the antecedents of work–life balance from the fit and balance perspective

    OpenAIRE

    Haar, Jarrod M.; Suñé Torrents, Albert; Russo, Marcello; Ollier-Malaterre, Ariane

    2018-01-01

    Drawing on the perceived work–family fit and balance perspective, this study investigates demands and resources as antecedents of work–life balance (WLB) across four countries (New Zealand, France, Italy and Spain), so as to provide empirical cross-national evidence. Using structural equation modelling analysis on a sample of 870 full time employees, we found that work demands, hours worked and family demands were negatively related to WLB, while job autonomy and supervisor support were posit...

  15. Population Thinking, Price’s Equation and the Analysis of Economic Evolution

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    2004-01-01

    applicable to economic evolution due to the development of what may be called a general evometrics. Central to this evometrics is a method for partitioning evolutionary change developed by George Price into the selection effect and what may be called the innovation effect. This method serves surprisingly...... well as a means of accounting for evolution and as a starting point for the explanation of evolution. The applications of Price’s equation cover the partitioning and analysis of relatively short-term evolutionary change within individual industries as well as the study of more complexly structured...... populations of firms. By extrapolating these applications of Price’s evometrics, the paper suggests that his approach may play a central role in the emerging evolutionary econometrics....

  16. Detailed Balance of Thermalization Dynamics in Rydberg-Atom Quantum Simulators.

    Science.gov (United States)

    Kim, Hyosub; Park, YeJe; Kim, Kyungtae; Sim, H-S; Ahn, Jaewook

    2018-05-04

    Dynamics of large complex systems, such as relaxation towards equilibrium in classical statistical mechanics, often obeys a master equation that captures essential information from the complexities. Here, we find that thermalization of an isolated many-body quantum state can be described by a master equation. We observe sudden quench dynamics of quantum Ising-like models implemented in our quantum simulator, defect-free single-atom tweezers in conjunction with Rydberg-atom interaction. Saturation of their local observables, a thermalization signature, obeys a master equation experimentally constructed by monitoring the occupation probabilities of prequench states and imposing the principle of the detailed balance. Our experiment agrees with theories and demonstrates the detailed balance in a thermalization dynamics that does not require coupling to baths or postulated randomness.

  17. Detailed Balance of Thermalization Dynamics in Rydberg-Atom Quantum Simulators

    Science.gov (United States)

    Kim, Hyosub; Park, YeJe; Kim, Kyungtae; Sim, H.-S.; Ahn, Jaewook

    2018-05-01

    Dynamics of large complex systems, such as relaxation towards equilibrium in classical statistical mechanics, often obeys a master equation that captures essential information from the complexities. Here, we find that thermalization of an isolated many-body quantum state can be described by a master equation. We observe sudden quench dynamics of quantum Ising-like models implemented in our quantum simulator, defect-free single-atom tweezers in conjunction with Rydberg-atom interaction. Saturation of their local observables, a thermalization signature, obeys a master equation experimentally constructed by monitoring the occupation probabilities of prequench states and imposing the principle of the detailed balance. Our experiment agrees with theories and demonstrates the detailed balance in a thermalization dynamics that does not require coupling to baths or postulated randomness.

  18. Gait and balance in the aging population: Fall prevention using innovation and technology.

    Science.gov (United States)

    Khanuja, Kavisha; Joki, Jaclyn; Bachmann, Gloria; Cuccurullo, Sara

    2018-04-01

    On a global basis, adults 65 years of age and older experience falls more frequently than younger individuals, and these often result in severe injuries as well as increased healthcare costs. Gait and balance disorders in this population are among the most common causes of falls and negatively influence quality of life and survivorship. Although falls are a major public health problem and guidelines/recommendations are available to physicians, many are fully aware of different assessments, tools, and resources available for intervention. Given the risk for potentially devastating outcomes if severe injuries occur secondary to a fall, fall prevention strategies in clinical offices is a timely consideration in today's health care landscape. This paper presents a three-tier model, comprising assessment, prevention, and intervention, to highlight methods, proactive programs, and innovative tools and technology that have been developed for fall prevention. Awareness of these resources will enhance the clinician's ability to accurately assess balance and gait, which can improve physical function, and decrease the risk of falls for both average-risk and high-risk older adults. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Balancing the Readiness Equation in Early Childhood Education Reform

    Science.gov (United States)

    Brown, Christopher P.

    2010-01-01

    As policy-makers continue to implement early childhood education reforms that frame the field as a mechanism that is to ready children for elementary school success, questions arise as to how the multiple variables in the readiness equation, such as the child, family, and program, are affected by these policies. The instrumental case study…

  20. Water balance at a low-level radioactive-waste disposal site

    Science.gov (United States)

    Healy, R.W.; Gray, J.R.; De Vries, G. M.; Mills, P.C.

    1989-01-01

    The water balance at a low-level radioactive-waste disposal site in northwestern Illinois was studied from July 1982 through June 1984. Continuous data collection allowed estimates to be made for each component of the water-balance equation independent of other components. The average annual precipitation was 948 millimeters. Average annual evapotranspiration was estimated at 637 millimeters, runoff was 160 millimeters, change in water storage in a waste-trench cover was 24 millimeters, and deep percolation was 208 millimeters. The magnitude of the difference between precipitation and all other components (81 millimeters per year) indicates that, in a similar environment, the water-budget method would be useful in estimating evapotranspiration, but questionable for estimation of other components. Precipitation depth and temporal distribution had a very strong effect on all other components of the water-balance equation. Due to the variability of precipitation from year to year, it appears that two years of data are inadequate for characterization of the long-term average water balance at the site.

  1. Water balance at a low-level radioactive-waste disposal site

    International Nuclear Information System (INIS)

    Healy, R.W.; Gray, J.R.; de Vries, M.P.; Mills, P.C.

    1989-01-01

    The water balance at a low-level radioactive-waste disposal site in northwestern Illinois was studied from July 1982 through June 1984. Continuous data collection allowed estimates to be made for each component of the water-balance equation independent of other components. The average annual precipitation was 948 millimeters. Average annual evapotranspiration was estimated at 637 millimeters, runoff was 160 millimeters, change in water storage in a waste-trench cover was 24 millimeters, and deep percolation was 208 millimeters. The magnitude of the difference between precipitation and all other components indicates that, in a similar environment, the water-budget method would be useful in estimating evapotranspiration, but questionable for estimation of other components. Precipitation depth and temporal distribution had a very strong effect on all other components of the water-balance equation. Due to the variability of precipitation from year to year, it appears that two years of data are inadequate for characterization of the long-term average water balance at the site

  2. Numerical simulation of flood inundation using a well-balanced kinetic scheme for the shallow water equations with bulk recharge and discharge

    Science.gov (United States)

    Ersoy, Mehmet; Lakkis, Omar; Townsend, Philip

    2016-04-01

    The flow of water in rivers and oceans can, under general assumptions, be efficiently modelled using Saint-Venant's shallow water system of equations (SWE). SWE is a hyperbolic system of conservation laws (HSCL) which can be derived from a starting point of incompressible Navier-Stokes. A common difficulty in the numerical simulation of HSCLs is the conservation of physical entropy. Work by Audusse, Bristeau, Perthame (2000) and Perthame, Simeoni (2001), proposed numerical SWE solvers known as kinetic schemes (KSs), which can be shown to have desirable entropy-consistent properties, and are thus called well-balanced schemes. A KS is derived from kinetic equations that can be integrated into the SWE. In flood risk assessment models the SWE must be coupled with other equations describing interacting meteorological and hydrogeological phenomena such as rain and groundwater flows. The SWE must therefore be appropriately modified to accommodate source and sink terms, so kinetic schemes are no longer valid. While modifications of SWE in this direction have been recently proposed, e.g., Delestre (2010), we depart from the extant literature by proposing a novel model that is "entropy-consistent" and naturally extends the SWE by respecting its kinetic formulation connections. This allows us to derive a system of partial differential equations modelling flow of a one-dimensional river with both a precipitation term and a groundwater flow model to account for potential infiltration and recharge. We exhibit numerical simulations of the corresponding kinetic schemes. These simulations can be applied to both real world flood prediction and the tackling of wider issues on how climate and societal change are affecting flood risk.

  3. Signature of balancing selection at the MC1R gene in Kunming dog populations.

    Directory of Open Access Journals (Sweden)

    Guo-dong Wang

    Full Text Available Coat color in dog breeds is an excellent character for revealing the power of artificial selection, as it is extremely diverse and likely the result of recent domestication. Coat color is generated by melanocytes, which synthesize pheomelanin (a red or yellow pigment or eumelanin (a black or brown pigment through the pigment type-switching pathway, and is regulated by three genes in dogs: MC1R (melanocortin receptor 1, CBD103 (β-defensin 103, and ASIP (agouti-signaling protein precursor. The genotypes of these three gene loci in dog breeds are associated with coat color pattern. Here, we resequenced these three gene loci in two Kunming dog populations and analyzed these sequences using population genetic approaches to identify evolutionary patterns that have occurred at these loci during the recent domestication and breeding of the Kunming dog. The analysis showed that MC1R undergoes balancing selection in both Kunming dog populations, and that the Fst value for MC1R indicates significant genetic differentiation across the two populations. In contrast, similar results were not observed for CBD103 or ASIP. These results suggest that high heterozygosity and allelic differences at the MC1R locus may explain both the mixed color coat, of yellow and black, and the difference in coat colors in both Kunming dog populations.

  4. The Accelerating And Constraining Factors Of The Coordinated And Balanced Development Of Regions

    Directory of Open Access Journals (Sweden)

    Vladimir Stepanovich Bochko

    2015-03-01

    Full Text Available In the article, the hypothesis that the modern industrial-technological process causes complication of socio-economic space and conducts to amplification its integrity, which, in turn, causes the need for the coordinated and balanced development, is proved. The process of complication of economic space is revealed as a result of number growth of communications caused by creation of the enterprises and organizations, by the change of structure of manufacture and increase of an educational level of the population. The characteristics of a new quality of economic space are given. The factors of the coordinated and balanced development of territories are allocated. The contents «a commercial combination» is shown. The necessity of transition to the system innovation thinking in conditions of becoming complicated economic space is proved. The idea of use «rebalancing of the economy « as a new vision of equation in conditions of crisis situations is offered. The conclusion is made that the result of theoretical and practical searches should become formation vital stability of development of territories, which is provided with intelligence — technological and moral — ethical level of the population, living on it

  5. The application of the pore population balance method to the calculation of the radiolytic weight loss and gas transport property changes of nuclear graphites

    International Nuclear Information System (INIS)

    Johnson, P.A.V.

    1982-01-01

    A pore population balance equation, previously used to describe the physical property changes of porous carbons during thermal oxidation in carbon dioxide, has been modified to treat the radiolytic oxidation of graphite in CO 2 /CO/CH 4 gas mixtures. Good agreement has been obtained between theory and experiment for the variation in the gas transport coefficients B, K and lambda of gilsonite graphite with absorbed radiation dose. Calculations indicate that the addition of blind pores to the transport porosity, and an allowance for the opening of closed pores with burn-off, do not account for the experimental fractional weight loss curve. An excellent fit is obtained, however, if a small volume of cylindrical pores of a mean radius approximately equal to the diffusion length of oxidising species in the coolant are present in the pore size spectrum. Gilsonite graphite therefore behaves as if the pore size distribution function is trimodal, with mean radii at about 0.5μm, 2.48μm and greater than or equal to 10.57μm. (author)

  6. Balance ability of 7 and 10 year old children in the population: results from a large UK birth cohort study.

    Science.gov (United States)

    Humphriss, Rachel; Hall, Amanda; May, Margaret; Macleod, John

    2011-01-01

    The literature contains many reports of balance function in children, but these are often on atypical samples taken from hospital-based clinics and may not be generalisable to the population as a whole. The purpose of the present study is to describe balance test results from a large UK-based birth cohort study. Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) were analysed. A total of 5402 children completed the heel-to-toe walking test at age 7 years. At age 10 years, 6915 children underwent clinical tests of balance including beam-walking, standing heel-to-toe on a beam and standing on one leg. A proportion of the children returned to the clinic for retesting within 3 months allowing test-retest agreement to be measured. Frequency distributions for each of the balance tests are given. Correlations between measures of dynamic balance at ages 7 and 10 years were weak. The static balance of 10 year old children was found to be poorer with eyes closed than with eyes open, and poorer in boys than in girls for all measures. Balance on one leg was poorer than heel-to-toe balance on a beam. A significant learning effect was found when first and second attempts of the tests were compared. Measures of static and dynamic balance appeared independent. Consistent with previous reports in the literature, test-retest reliability was found to be low. This study provides information about the balance ability of children aged 7 and 10 years and provides clinicians with reference data for balance tests commonly used in the paediatric clinic. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  7. Terms of trade instability and balance of payments adjustment in ...

    African Journals Online (AJOL)

    Terms of trade instability and balance of payments adjustment in Nigeria: A simultaneous equation modelling. ... International Journal of Development and Management Review ... This implies that for any 1percent instability (shock) in terms of trade, balance of payment will be adversely affected by about 1.8 percent. Hence ...

  8. Mechanical Balance Laws for Boussinesq Models of Surface Water Waves

    Science.gov (United States)

    Ali, Alfatih; Kalisch, Henrik

    2012-06-01

    Depth-integrated long-wave models, such as the shallow-water and Boussinesq equations, are standard fare in the study of small amplitude surface waves in shallow water. While the shallow-water theory features conservation of mass, momentum and energy for smooth solutions, mechanical balance equations are not widely used in Boussinesq scaling, and it appears that the expressions for many of these quantities are not known. This work presents a systematic derivation of mass, momentum and energy densities and fluxes associated with a general family of Boussinesq systems. The derivation is based on a reconstruction of the velocity field and the pressure in the fluid column below the free surface, and the derivation of differential balance equations which are of the same asymptotic validity as the evolution equations. It is shown that all these mechanical quantities can be expressed in terms of the principal dependent variables of the Boussinesq system: the surface excursion η and the horizontal velocity w at a given level in the fluid.

  9. Task oriented training improves the balance outcome & reducing fall risk in diabetic population.

    Science.gov (United States)

    Ghazal, Javeria; Malik, Arshad Nawaz; Amjad, Imran

    2016-01-01

    The objective was to determine the balance impairments and to compare task oriented versus traditional balance training in fall reduction among diabetic patients. The randomized control trial with descriptive survey and 196 diabetic patients were recruited to assess balance impairments through purposive sampling technique. Eighteen patients were randomly allocated into two groups; task oriented balance training group TOB (n=8) and traditional balance training group TBT (n=10). The inclusion criteria were 30-50 years age bracket and diagnosed cases of Diabetes Mellitus with neuropathy. The demographics were taken through standardized & valid assessment tools include Berg Balance Scale and Functional Reach Test. The measurements were obtained at baseline, after 04 and 08 weeks of training. The mean age of the participants was 49 ±6.79. The result shows that 165(84%) were at moderate risk of fall and 31(15%) were at mild risk of fall among total 196 diabetic patients. There was significant improvement (p balance training group for dynamic balance, anticipatory balance and reactive balance after 8 weeks of training as compare to traditional balance training. Task oriented balance training is effective in improving the dynamic, anticipator and reactive balance. The task oriented training reduces the risk of falling through enhancing balance outcome.

  10. Multi-scale kinetic description of granular clusters: invariance, balance, and temperature

    Science.gov (United States)

    Capriz, Gianfranco; Mariano, Paolo Maria

    2017-12-01

    We discuss a multi-scale continuum representation of bodies made of several mass particles flowing independently each other. From an invariance procedure and a nonstandard balance of inertial actions, we derive the balance equations introduced in earlier work directly in pointwise form, essentially on the basis of physical plausibility. In this way, we analyze their foundations. Then, we propose a Boltzmann-type equation for the distribution of kinetic energies within control volumes in space and indicate how such a distribution allows us to propose a definition of (granular) temperature along processes far from equilibrium.

  11. The Enskog Equation for Confined Elastic Hard Spheres

    Science.gov (United States)

    Maynar, P.; García de Soria, M. I.; Brey, J. Javier

    2018-03-01

    A kinetic equation for a system of elastic hard spheres or disks confined by a hard wall of arbitrary shape is derived. It is a generalization of the modified Enskog equation in which the effects of the confinement are taken into account and it is supposed to be valid up to moderate densities. From the equation, balance equations for the hydrodynamic fields are derived, identifying the collisional transfer contributions to the pressure tensor and heat flux. A Lyapunov functional, H[f], is identified. For any solution of the kinetic equation, H decays monotonically in time until the system reaches the inhomogeneous equilibrium distribution, that is a Maxwellian distribution with a density field consistent with equilibrium statistical mechanics.

  12. Solution of hydraulic nets, by means of the application of the pattern of balance of nodes and the method of linealization of equations

    International Nuclear Information System (INIS)

    Narvaez Rincon, Paulo Cesar; Granados Jorge Armando, Barrera Hector

    1999-01-01

    The dimension of nets of fluids distribution is a common problem to different areas of the engineering, as the chemistry and the civil, present in the design of aqueducts, distribution systems of domiciliary gas, nets against fire and plants of chemical transformation. This work presents a model for its simulation, by means of the application of the balance of nodes and the theory of linealization of equations, it allows to know a complex net, in which they can be present, accessories, bombs, control valves, aspersion mouthpieces and process equipment. It is applicable to open, closed nets or combinations of two

  13. Dynamic power balance analysis in JET

    International Nuclear Information System (INIS)

    Matthews, G F; Silburn, S A; Challis, C D; Iglesias, D; King, D; Eich, T; Sieglin, B; Contributors, JET

    2017-01-01

    The full scale realisation of nuclear fusion as an energy source requires a detailed understanding of power and energy balance in current experimental devices. In this we explore whether a global power balance model in which some of the calibration factors applied to the source or sink terms are fitted to the data can provide insight into possible causes of any discrepancies in power and energy balance seen in the JET tokamak. We show that the dynamics in the power balance can only be properly reproduced by including the changes in the thermal stored energy which therefore provides an additional opportunity to cross calibrate other terms in the power balance equation. Although the results are inconclusive with respect to the original goal of identifying the source of the discrepancies in the energy balance, we do find that with optimised parameters an extremely good prediction of the total power measured at the outer divertor target can be obtained over a wide range of pulses with time resolution up to ∼25 ms. (paper)

  14. Population stochastic modelling (PSM)--an R package for mixed-effects models based on stochastic differential equations.

    Science.gov (United States)

    Klim, Søren; Mortensen, Stig Bousgaard; Kristensen, Niels Rode; Overgaard, Rune Viig; Madsen, Henrik

    2009-06-01

    The extension from ordinary to stochastic differential equations (SDEs) in pharmacokinetic and pharmacodynamic (PK/PD) modelling is an emerging field and has been motivated in a number of articles [N.R. Kristensen, H. Madsen, S.H. Ingwersen, Using stochastic differential equations for PK/PD model development, J. Pharmacokinet. Pharmacodyn. 32 (February(1)) (2005) 109-141; C.W. Tornøe, R.V. Overgaard, H. Agersø, H.A. Nielsen, H. Madsen, E.N. Jonsson, Stochastic differential equations in NONMEM: implementation, application, and comparison with ordinary differential equations, Pharm. Res. 22 (August(8)) (2005) 1247-1258; R.V. Overgaard, N. Jonsson, C.W. Tornøe, H. Madsen, Non-linear mixed-effects models with stochastic differential equations: implementation of an estimation algorithm, J. Pharmacokinet. Pharmacodyn. 32 (February(1)) (2005) 85-107; U. Picchini, S. Ditlevsen, A. De Gaetano, Maximum likelihood estimation of a time-inhomogeneous stochastic differential model of glucose dynamics, Math. Med. Biol. 25 (June(2)) (2008) 141-155]. PK/PD models are traditionally based ordinary differential equations (ODEs) with an observation link that incorporates noise. This state-space formulation only allows for observation noise and not for system noise. Extending to SDEs allows for a Wiener noise component in the system equations. This additional noise component enables handling of autocorrelated residuals originating from natural variation or systematic model error. Autocorrelated residuals are often partly ignored in PK/PD modelling although violating the hypothesis for many standard statistical tests. This article presents a package for the statistical program R that is able to handle SDEs in a mixed-effects setting. The estimation method implemented is the FOCE(1) approximation to the population likelihood which is generated from the individual likelihoods that are approximated using the Extended Kalman Filter's one-step predictions.

  15. Linear quadratic Gaussian balancing for discrete-time infinite-dimensional linear systems

    NARCIS (Netherlands)

    Opmeer, MR; Curtain, RF

    2004-01-01

    In this paper, we study the existence of linear quadratic Gaussian (LQG)-balanced realizations for discrete-time infinite-dimensional systems. LQG-balanced realizations are those for which the smallest nonnegative self-adjoint solutions of the control and filter Riccati equations are equal. We show

  16. Energy balance in turbulent weakly ionized ionospheric plasma

    International Nuclear Information System (INIS)

    Dyatko, N.A.; Mishin, E.V.; Telegin, V.A.

    1994-01-01

    On the base of numerical solution of the Boltzmann equation are determined the electron distribution function and energy balance in the case if the longitudinal current exceeds the critical one and the resistance becames anomalously high one. In the equation are accounted for both electron scattering by plasma density fluctuations and electron elastic and inelastic collisions with atoms and molecules and electron-electron collisions

  17. The social balance sheet 2004

    OpenAIRE

    Ph. Delhez; P. Heuse

    2005-01-01

    Each year, in the 4th quarter’s Economic Review, the National Bank examines the provisional results of the social balance sheets. As all the social balance sheets are not yet available for 2004, the study is based on a limited population of enterprises, compiled according to the principle of a constant sample. This population is made up of 38,530 enterprises employing around 1,331,000 workers in 2004. The main results of the analysis, in terms of employment, working hours, labour cost and tra...

  18. Interchangeability of the Wii Balance Board for Bipedal Balance Assessment.

    Science.gov (United States)

    Bonnechère, Bruno; Jansen, Bart; Omelina, Lubos; Rooze, Marcel; Van Sint Jan, Serge

    2015-08-27

    Since 2010, an increasing interest in more portable and flexible hardware for balance and posture assessment led to previously published studies determining whether or not the Wii Balance Board could be used to assess balance and posture, both scientifically and clinically. However, no previous studies aimed at comparing results from different Wii Balance Boards for clinical balance evaluation exist. The objective of this crossover study is to assess the interchangeability of the Wii Balance Board. A total of 6 subjects participated in the study and their balance was assessed using 4 different Wii Balance Boards. Trials were recorded simultaneously with Wii Balance Boards and with a laboratory force plate. Nine relevant clinical parameters were derived from center of pressure displacement data obtained from Wii Balance Board and force plate systems. Intraclass correlation coefficients (ICC), F tests, and Friedman tests were computed to assess the agreement between trials and to compare the Wii Balance Board and force plate results. Excellent correlations were found between the Wii Balance Board and force plate (mean ρ =.83). With the exception of 2 parameters, strong to excellent agreements were found for the 7 remaining parameters (ICC=.96). No significant differences were found between trials recorded with different Wii Balance Boards. Our results indicate that for most of the parameters analyzed, balance and posture assessed with one Wii Balance Board were statistically similar to results obtained from another. Furthermore, the good correlation between the Wii Balance Board and force plate results shows that Wii Balance Boards can be reliably used for scientific assessment using most of the parameters analyzed in this study. These results also suggest that the Wii Balance Board could be used in multicenter studies and therefore, would allow for the creation of larger populations for clinical studies. Ethical Committee of the Erasme Hospital (CCB B406201215142

  19. A study on the force balance of an unbalanced globe valve

    International Nuclear Information System (INIS)

    Yang, Sang Min; Cho, Taik Dong; Ko, Sung Ho; Lee, Ho Young

    2007-01-01

    A pneumatic control valve is a piping element that controls the volumetric flow rate and pressure of a fluid: it is necessary to analyze the characteristics of the forces with respect to the opening of the valve in order to evaluate its operating performance. The forces occurring during operation are: resisting force and actuator force, where the load resistance is mostly affected by the fluid pressure difference of the valve. In this study, a force balance equation derived from the equilibrium relationship between the resisting force and the actuator force of an unbalanced globe valve is proposed, and the force balance equations are used to model the dynamic equations of a pneumatic unbalanced globe valve installed in nuclear power plants. A CFD analysis is also carried out to evaluate the pressure distribution and forces acting on the top and bottom planes of the valve plug. The results of this analysis have been verified through experimentation. This study has shown that the fluid pressure difference between the inlet and outlet of the valve, measured from the force balance equation of an unbalanced valve, should actually be examined with the fluid-pressure difference between the top and bottom side of the valve plug

  20. Well-balanced Arbitrary-Lagrangian-Eulerian finite volume schemes on moving nonconforming meshes for the Euler equations of gas dynamics with gravity

    Science.gov (United States)

    Gaburro, Elena; Castro, Manuel J.; Dumbser, Michael

    2018-06-01

    In this work, we present a novel second-order accurate well-balanced arbitrary Lagrangian-Eulerian (ALE) finite volume scheme on moving nonconforming meshes for the Euler equations of compressible gas dynamics with gravity in cylindrical coordinates. The main feature of the proposed algorithm is the capability of preserving many of the physical properties of the system exactly also on the discrete level: besides being conservative for mass, momentum and total energy, also any known steady equilibrium between pressure gradient, centrifugal force, and gravity force can be exactly maintained up to machine precision. Perturbations around such equilibrium solutions are resolved with high accuracy and with minimal dissipation on moving contact discontinuities even for very long computational times. This is achieved by the novel combination of well-balanced path-conservative finite volume schemes, which are expressly designed to deal with source terms written via non-conservative products, with ALE schemes on moving grids, which exhibit only very little numerical dissipation on moving contact waves. In particular, we have formulated a new HLL-type and a novel Osher-type flux that are both able to guarantee the well balancing in a gas cloud rotating around a central object. Moreover, to maintain a high level of quality of the moving mesh, we have adopted a nonconforming treatment of the sliding interfaces that appear due to the differential rotation. A large set of numerical tests has been carried out in order to check the accuracy of the method close and far away from the equilibrium, both, in one- and two-space dimensions.

  1. Predictive coding of dynamical variables in balanced spiking networks.

    Science.gov (United States)

    Boerlin, Martin; Machens, Christian K; Denève, Sophie

    2013-01-01

    Two observations about the cortex have puzzled neuroscientists for a long time. First, neural responses are highly variable. Second, the level of excitation and inhibition received by each neuron is tightly balanced at all times. Here, we demonstrate that both properties are necessary consequences of neural networks that represent information efficiently in their spikes. We illustrate this insight with spiking networks that represent dynamical variables. Our approach is based on two assumptions: We assume that information about dynamical variables can be read out linearly from neural spike trains, and we assume that neurons only fire a spike if that improves the representation of the dynamical variables. Based on these assumptions, we derive a network of leaky integrate-and-fire neurons that is able to implement arbitrary linear dynamical systems. We show that the membrane voltage of the neurons is equivalent to a prediction error about a common population-level signal. Among other things, our approach allows us to construct an integrator network of spiking neurons that is robust against many perturbations. Most importantly, neural variability in our networks cannot be equated to noise. Despite exhibiting the same single unit properties as widely used population code models (e.g. tuning curves, Poisson distributed spike trains), balanced networks are orders of magnitudes more reliable. Our approach suggests that spikes do matter when considering how the brain computes, and that the reliability of cortical representations could have been strongly underestimated.

  2. Inviscid limit of stochastic damped 2D Navier–Stokes equations

    International Nuclear Information System (INIS)

    Bessaih, Hakima; Ferrario, Benedetta

    2014-01-01

    We consider the inviscid limit of the stochastic damped 2D Navier–Stokes equations. We prove that, when the viscosity vanishes, the stationary solution of the stochastic damped Navier–Stokes equations converges to a stationary solution of the stochastic damped Euler equation and that the rate of dissipation of enstrophy converges to zero. In particular, this limit obeys an enstrophy balance. The rates are computed with respect to a limit measure of the unique invariant measure of the stochastic damped Navier–Stokes equations. (paper)

  3. Vortex dynamics equation in type-II superconductors in a temperature gradient

    International Nuclear Information System (INIS)

    Vega Monroy, R.; Sarmiento Castillo, J.; Puerta Torres, D.

    2010-01-01

    In this work we determined a vortex dynamics equation in a temperature gradient in the frame of the time dependent Ginzburg-Landau equation. In this sense, we derived a local solvability condition, which governs the vortex dynamics. Also, we calculated the explicit form for the force coefficients, which are the keys for the understanding of the balance equation due to vortex interactions with the environment. (author)

  4. Vortex dynamics equation in type-II superconductors in a temperature gradient

    Energy Technology Data Exchange (ETDEWEB)

    Vega Monroy, R.; Sarmiento Castillo, J. [Universidad del Atlantico, Barranquilla (Colombia). Facultad de Ciencias Basicas; Puerta Torres, D. [Universidad de Cartagena (Colombia). Facultad de Ciencias Exactas

    2010-12-15

    In this work we determined a vortex dynamics equation in a temperature gradient in the frame of the time dependent Ginzburg-Landau equation. In this sense, we derived a local solvability condition, which governs the vortex dynamics. Also, we calculated the explicit form for the force coefficients, which are the keys for the understanding of the balance equation due to vortex interactions with the environment. (author)

  5. On the parallel momentum balance in low pressure plasmas with an inhomogeneous magnetic field

    International Nuclear Information System (INIS)

    Smolyakov, A.I.; Garbet, X.; Bourdelle, C.

    2009-01-01

    This paper describes the structure of the parallel momentum balance in low pressure plasmas with an inhomogeneous magnetic field. The parallel momentum balance equation is derived from magnetohydrodynamic equations by an expansion in the inverse magnetic field 1/B as a small parameter. Contributions of the gyroviscosity and inertia terms are clarified. It is shown that magnetic field curvature leads to important coupling of parallel flow with fluctuations of the electric field and plasma pressure.

  6. Dose concept of oncological hyperthermia: Heat-equation considering the cell destruction

    Directory of Open Access Journals (Sweden)

    Szasz A

    2006-01-01

    Full Text Available We shall assume, of course, that the objective of hyperthermia is to destroy the malignant cells. Destruction definitely needs energy. Description and quality assurance of hyperthermia use the Pennes heat equation to describe the processes. However the energy balance of the Pennes-equation does not contain the hyperthermic cell-destruction energy, which is a mandatory factor of the process. We propose a generalization of the Pennes-equation, inducing the entire energy balance. The new paradigm could be a theoretical basis of the till now empirical dose-construction for oncological hyperthermia. The cell destruction is a non-equilibrium thermodynamical process, described by the equations of chemical reactions. The dynamic behavior (time dependence has to be considered in this approach. We are going to define also a dose concept that can be objectively compared with other oncological methods. We show how such empirical dose as CEM43oC could be based theoretically as well.

  7. Dynamic balancing of planar mechanisms using toric geometry

    OpenAIRE

    Moore, Brian; Schicho, Josef; Gosselin, Clement M.

    2007-01-01

    In this paper, a new method to determine the complete set of dynamically balanced planar four-bar mechanims is presented. Using complex variables to model the kinematics of the mechanism, the dynamic balancing constraints are written as algebraic equations over complex variables and joint angular velocities. After elimination of the joint angular velocity variables, the problem is formulated as a problem of factorization of Laurent polynomials. Using toric polynomial division, necessary and s...

  8. Work-Family Balance and Psychosocial Adjustment of Married International Students

    OpenAIRE

    Gökçe Bulgan; Ayşe Çiftçi

    2018-01-01

    The authors investigated how work-family balance mediated the relationship between personality traits, gender roles, social support, and psychosocial adjustment. Data were collected from 243 married international graduate students (MIGSs) studying in the United States. Results of structural equation modeling indicated that personality traits influence the psychosocial adjustment process. In addition, being extraverted, agreeable, and conscientious contributed to balanc...

  9. Linking dissolution to disintegration in immediate release tablets using image analysis and a population balance modelling approach.

    Science.gov (United States)

    Wilson, David; Wren, Stephen; Reynolds, Gavin

    2012-01-01

    In order to achieve an improved understanding of disintegration and dissolution phenomena for an immediate release tablet formulation, a technique to monitor the number and size of particles entrained within the dissolution media was developed in combination with a population balancing model. Tablets were first characterized for crushing force, disintegration time and dissolution performance using standard USP methodologies. The performance of the tablets was then assessed using a new measurement system which links a "QicPic" particle imaging device to a USP dissolution vessel. This system enables us to measure the number and size of particles generated during tablet dissolution. The population balance mathematical model allowed a tablet erosion rate to be manipulated to fit the experimental data. Results showed that tablets with differing crushing forces showed different dissolution behaviors that could be explained by differing rates of particle release into the dissolution media. These behaviors were then successfully modeled to provide a description of the dissolution and disintegration behavior of the tablets in terms of a tablet erosion rate. A new approach was developed that allowed the description of the dissolution behaviors of the tablets in terms of the rate that they release particles into solution. This was then successfully modeled in terms of a tablet erosion rate.

  10. Task oriented training improves the balance outcome & reducing fall risk in diabetic population

    OpenAIRE

    Ghazal, Javeria; Malik, Arshad Nawaz; Amjad, Imran

    2016-01-01

    Objectives: The objective was to determine the balance impairments and to compare task oriented versus traditional balance training in fall reduction among diabetic patients. Methods: The randomized control trial with descriptive survey and 196 diabetic patients were recruited to assess balance impairments through purposive sampling technique. Eighteen patients were randomly allocated into two groups; task oriented balance training group TOB (n=8) and traditional balance training group TBT (n...

  11. Power balance equation in electron beam evaporation process

    International Nuclear Information System (INIS)

    Blumenfeld, L.; Soubbaramayer.

    1994-01-01

    The aim of the paper is to solve the equation giving the total power of the gun, used in the electron beam evaporation process, in terms of the power used to generated the vapor stream and the three main power losses due to three parasite phenomena: turbulent thermal convection in the molten pool, electron back scattering and heat radiation from the vapor emitting surface. Scaling laws are first reviewed and results are given with the example of the evaporation of aluminium with a 5 kW axisymmetric gun working in steady state mode. The influence of an applied magnetic field on the evaporation rate is also examined. 5 refs., 3 figs., 1 tab

  12. Pressure correction schemes for compressible flows: application to baro-tropic Navier-Stokes equations and to drift-flux model; Methodes de correction de pression pour les ecoulements compressibles: application aux equations de Navier-Stokes barotropes et au modele de derive

    Energy Technology Data Exchange (ETDEWEB)

    Gastaldo, L

    2007-11-15

    We develop in this PhD thesis a simulation tool for bubbly flows encountered in some late phases of a core-melt accident in pressurized water reactors, when the flow of molten core and vessel structures comes to chemically interact with the concrete of the containment floor. The physical modelling is based on the so-called drift-flux model, consisting of mass balance and momentum balance equations for the mixture (Navier-Stokes equations) and a mass balance equation for the gaseous phase. First, we propose a pressure correction scheme for the compressible Navier-Stokes equations based on mixed non-conforming finite elements. An ad hoc discretization of the advection operator, by a finite volume technique based on a dual mesh, ensures the stability of the velocity prediction step. A priori estimates for the velocity and the pressure yields the existence of the solution. We prove that this scheme is stable, in the sense that the discrete entropy is decreasing. For the conservation equation of the gaseous phase, we build a finite volume discretization which satisfies a discrete maximum principle. From this last property, we deduce the existence and the uniqueness of the discrete solution. Finally, on the basis of these works, a conservative and monotone scheme which is stable in the low Mach number limit, is build for the drift-flux model. This scheme enjoys, moreover, the following property: the algorithm preserves a constant pressure and velocity through moving interfaces between phases (i.e. contact discontinuities of the underlying hyperbolic system). In order to satisfy this property at the discrete level, we build an original pressure correction step which couples the mass balance equation with the transport terms of the gas mass balance equation, the remaining terms of the gas mass balance being taken into account with a splitting method. We prove the existence of a discrete solution for the pressure correction step. Numerical results are presented; they

  13. New exact solutions of sixth-order thin-film equation

    Directory of Open Access Journals (Sweden)

    Wafaa M. Taha

    2014-01-01

    Full Text Available TheG′G-expansion method is used for the first time to find traveling-wave solutions for the sixth-order thin-film equation, where related balance numbers are not the usual positive integers. New types of exact traveling-wave solutions, such as – solitary wave solutions, are obtained the sixth-order thin-film equation, when parameters are taken at special values.

  14. Liquefaction of Saturated Soil and the Diffusion Equation

    Science.gov (United States)

    Sawicki, Andrzej; Sławińska, Justyna

    2015-06-01

    The paper deals with the diffusion equation for pore water pressures with the source term, which is widely promoted in the marine engineering literature. It is shown that such an equation cannot be derived in a consistent way from the mass balance and the Darcy law. The shortcomings of the artificial source term are pointed out, including inconsistencies with experimental data. It is concluded that liquefaction and the preceding process of pore pressure generation and the weakening of the soil skeleton should be described by constitutive equations within the well-known framework of applied mechanics. Relevant references are provided

  15. An introduction to differential equations using MATLAB

    CERN Document Server

    Butt, Rizwan

    2016-01-01

    An Introduction to Differential Equations using MATLAB exploits the symbolic, numerical, and graphical capabilitiesof MATLAB to develop a thorough understanding of differential equations algorithms. This book provides the readerwith numerous applications, m-files, and practical examples to problems. Balancing theoretical concepts withcomputational speed and accuracy, the book includes numerous short programs in MATLAB that can be used to solveproblems involving first-and higher-order differential equations, Laplace transforms, linear systems of differentialequations, numerical solutions of differential equations, computer graphics, and more. The author emphasizes thebasic ideas of analytical and numerical techniques and the uses of modern mathematical software (MATLAB) ratherthan relying only on complex mathematical derivations to engineers, mathematician, computer scientists, andphysicists or for use as a textbook in applied or computational courses.A CD-ROM with all the figures, codes, solutions, appendices...

  16. Selectivity and sparseness in randomly connected balanced networks.

    Directory of Open Access Journals (Sweden)

    Cengiz Pehlevan

    Full Text Available Neurons in sensory cortex show stimulus selectivity and sparse population response, even in cases where no strong functionally specific structure in connectivity can be detected. This raises the question whether selectivity and sparseness can be generated and maintained in randomly connected networks. We consider a recurrent network of excitatory and inhibitory spiking neurons with random connectivity, driven by random projections from an input layer of stimulus selective neurons. In this architecture, the stimulus-to-stimulus and neuron-to-neuron modulation of total synaptic input is weak compared to the mean input. Surprisingly, we show that in the balanced state the network can still support high stimulus selectivity and sparse population response. In the balanced state, strong synapses amplify the variation in synaptic input and recurrent inhibition cancels the mean. Functional specificity in connectivity emerges due to the inhomogeneity caused by the generative statistical rule used to build the network. We further elucidate the mechanism behind and evaluate the effects of model parameters on population sparseness and stimulus selectivity. Network response to mixtures of stimuli is investigated. It is shown that a balanced state with unselective inhibition can be achieved with densely connected input to inhibitory population. Balanced networks exhibit the "paradoxical" effect: an increase in excitatory drive to inhibition leads to decreased inhibitory population firing rate. We compare and contrast selectivity and sparseness generated by the balanced network to randomly connected unbalanced networks. Finally, we discuss our results in light of experiments.

  17. Evidences for balancing selection from PAH-BglII and PAH-EcoRI polymorphisms in Isfahan population

    Directory of Open Access Journals (Sweden)

    Zahra Fazeli Attar

    2010-01-01

    Full Text Available Two polymorphic markers including BglII and EcoRI, were identified at intron 1 and intron 5 of PAH gene. In order to test whether these polymorphisms are behaving as neutral alleles or are being subjected to selective pressures in Isfahan population, 110 individuals were genotyped by PCR-RFLP. The Arlequin input file was prepared by use of phase-known haplotype data and Neutrality tests (Tajima D test and Fu’s Fs test were done using Arlequin program. 42 individuals were found heterozygous for both polymorphisms whose haplotype phase remained unknown. The BglII-EcoRI haplotype phase was known only at 68 individuals who were used for preparation of input file. Tajima's D value and Fs value at Isfahan population were 1.7 and 1.02, respectively. Positive values of Fs and D>0 indicated that these polymorphisms are under selection pressure at Isfahan population. Although these polymorphisms were in the non-coding region of PAH gene, but these were not neutral alleles and positive values of these tests provided evidence for balancing selection of these polymorphisms at Isfahan population. The results of this study could improve our understanding of evolutionary history and structure of Isfahan population.

  18. Cash flow in the context of economic equation of continuity

    Directory of Open Access Journals (Sweden)

    Fernando Gómez Villarraga

    2006-07-01

    Full Text Available The mathematic scheme, known as economic equation of continuity, is established for the balance of economic resources. In order to apply this equation it is necessary to determine an economic volume of control. The patrimonial equation is also proposed as a speed equationfor this volurne. The integral equation of economic continuity is applied to the «cash» system along with the integral patrimonial equation and so it gets expressions that correspond to model to elaborate cashflow statement with the particularities of the direct and indirect method. This model generales a useful definition for the calculation of this basic financial statement classified by operating, investing and financing activities.

  19. Legged locomotion : Balance, control and tools - from equation to action

    OpenAIRE

    Ridderström, Christian

    2003-01-01

    This thesis is about control and balance stability of leggedlocomotion. It also presents a combination of tools that makesit easier to design controllers for large and complicated robotsystems. The thesis is divided into four parts. The first part studies and analyzes how walking machines arecontrolled, examining the literature of over twenty machinesbriefly, and six machines in detail. The goal is to understandhow the controllers work on a level below task and pathplanning, but above actuato...

  20. Computational fluid dynamics and population balance modelling of nucleate boiling of cryogenic liquids: Theoretical developments

    Directory of Open Access Journals (Sweden)

    Guan Heng Yeoh

    2016-12-01

    interfacial mass, momentum and energy exchange terms that appear in the transport equations generally require the determination of the Sauter mean diameter or interfacial area concentration, which strongly governs the fluid flow and heat transfer in the bulk liquid. In order to accommodate the dynamically changing bubble sizes that are prevalent in the bulk liquid, the mechanistic approach based on the population balance model allows the appropriate prediction of local distributions of Sauter mean diameter or interfacial area concentration, which in turn can improve the predictions of the interfacial mass, momentum and energy exchanges that occur across the interface between the phases. Need for further developments are discussed.

  1. Balance Treatment Ameliorates Anxiety and Increases Self-Esteem in Children with Comorbid Anxiety and Balance Disorder

    Science.gov (United States)

    Bart, Orit; Bar-Haim, Yair; Weizman, Einat; Levin, Moran; Sadeh, Avi; Mintz, Matti

    2009-01-01

    Comorbidity between balance and anxiety disorders in adult population is a well-studied clinical entity. Children might be particularly prone to develop balance-anxiety comorbidity, but surprisingly they are practically neglected in this field of research. The consequence is that children are treated for what seems to be the primary disorder…

  2. Computations of Torque-Balanced Coaxial Rotor Flows

    Science.gov (United States)

    Yoon, Seokkwan; Chan, William M.; Pulliam, Thomas H.

    2017-01-01

    Interactional aerodynamics has been studied for counter-rotating coaxial rotors in hover. The effects of torque balancing on the performance of coaxial-rotor systems have been investigated. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, and a hybrid turbulence model. Computational results for an experimental model are compared to available data. The results for a coaxial quadcopter vehicle with and without torque balancing are discussed. Understanding interactions in coaxial-rotor flows would help improve the design of next-generation autonomous drones.

  3. Pressure correction schemes for compressible flows: application to baro-tropic Navier-Stokes equations and to drift-flux model

    International Nuclear Information System (INIS)

    Gastaldo, L.

    2007-11-01

    We develop in this PhD thesis a simulation tool for bubbly flows encountered in some late phases of a core-melt accident in pressurized water reactors, when the flow of molten core and vessel structures comes to chemically interact with the concrete of the containment floor. The physical modelling is based on the so-called drift-flux model, consisting of mass balance and momentum balance equations for the mixture (Navier-Stokes equations) and a mass balance equation for the gaseous phase. First, we propose a pressure correction scheme for the compressible Navier-Stokes equations based on mixed non-conforming finite elements. An ad hoc discretization of the advection operator, by a finite volume technique based on a dual mesh, ensures the stability of the velocity prediction step. A priori estimates for the velocity and the pressure yields the existence of the solution. We prove that this scheme is stable, in the sense that the discrete entropy is decreasing. For the conservation equation of the gaseous phase, we build a finite volume discretization which satisfies a discrete maximum principle. From this last property, we deduce the existence and the uniqueness of the discrete solution. Finally, on the basis of these works, a conservative and monotone scheme which is stable in the low Mach number limit, is build for the drift-flux model. This scheme enjoys, moreover, the following property: the algorithm preserves a constant pressure and velocity through moving interfaces between phases (i.e. contact discontinuities of the underlying hyperbolic system). In order to satisfy this property at the discrete level, we build an original pressure correction step which couples the mass balance equation with the transport terms of the gas mass balance equation, the remaining terms of the gas mass balance being taken into account with a splitting method. We prove the existence of a discrete solution for the pressure correction step. Numerical results are presented; they

  4. QCD evolution equations for high energy partons in nuclear matter

    CERN Document Server

    Kinder-Geiger, Klaus; Geiger, Klaus; Mueller, Berndt

    1994-01-01

    We derive a generalized form of Altarelli-Parisi equations to decribe the time evolution of parton distributions in a nuclear medium. In the framework of the leading logarithmic approximation, we obtain a set of coupled integro- differential equations for the parton distribution functions and equations for the virtuality (``age'') distribution of partons. In addition to parton branching processes, we take into account fusion and scattering processes that are specific to QCD in medium. Detailed balance between gain and loss terms in the resulting evolution equations correctly accounts for both real and virtual contributions which yields a natural cancellation of infrared divergences.

  5. Consistent three-equation model for thin films

    Science.gov (United States)

    Richard, Gael; Gisclon, Marguerite; Ruyer-Quil, Christian; Vila, Jean-Paul

    2017-11-01

    Numerical simulations of thin films of newtonian fluids down an inclined plane use reduced models for computational cost reasons. These models are usually derived by averaging over the fluid depth the physical equations of fluid mechanics with an asymptotic method in the long-wave limit. Two-equation models are based on the mass conservation equation and either on the momentum balance equation or on the work-energy theorem. We show that there is no two-equation model that is both consistent and theoretically coherent and that a third variable and a three-equation model are required to solve all theoretical contradictions. The linear and nonlinear properties of two and three-equation models are tested on various practical problems. We present a new consistent three-equation model with a simple mathematical structure which allows an easy and reliable numerical resolution. The numerical calculations agree fairly well with experimental measurements or with direct numerical resolutions for neutral stability curves, speed of kinematic waves and of solitary waves and depth profiles of wavy films. The model can also predict the flow reversal at the first capillary trough ahead of the main wave hump.

  6. Development of a Population Balance Model of a pharmaceutical drying process and testing of solution methods

    DEFF Research Database (Denmark)

    Mortier, Séverine Thérèse F.C.; Gernaey, Krist; De Beer, Thomas

    2013-01-01

    Drying is frequently used in the production of pharmaceutical tablets. Simulation-based control strategy development for such a drying process requires a detailed model. First, the drying of wet granules is modelled using a Population Balance Model. A growth term based on a reduced model was used......, which describes the decrease of the moisture content, to follow the moisture content distribution for a batch of granules. Secondly, different solution methods for solving the PBM are compared. The effect of grid size (discretization methods) is analyzed in terms of accuracy and calculation time. All...

  7. How many stakes are required to measure the mass balance of a glacier?

    Science.gov (United States)

    Fountain, A.G.; Vecchia, A.

    1999-01-01

    Glacier mass balance is estimated for South Cascade Glacier and Maclure Glacier using a one-dimensional regression of mass balance with altitude as an alternative to the traditional approach of contouring mass balance values. One attractive feature of regression is that it can be applied to sparse data sets where contouring is not possible and can provide an objective error of the resulting estimate. Regression methods yielded mass balance values equivalent to contouring methods. The effect of the number of mass balance measurements on the final value for the glacier showed that sample sizes as small as five stakes provided reasonable estimates, although the error estimates were greater than for larger sample sizes. Different spatial patterns of measurement locations showed no appreciable influence on the final value as long as different surface altitudes were intermittently sampled over the altitude range of the glacier. Two different regression equations were examined, a quadratic, and a piecewise linear spline, and comparison of results showed little sensitivity to the type of equation. These results point to the dominant effect of the gradient of mass balance with altitude of alpine glaciers compared to transverse variations. The number of mass balance measurements required to determine the glacier balance appears to be scale invariant for small glaciers and five to ten stakes are sufficient.

  8. The verification of the Taylor-expansion moment method in solving aerosol breakage

    Directory of Open Access Journals (Sweden)

    Yu Ming-Zhou

    2012-01-01

    Full Text Available The combination of the method of moment, characterizing the particle population balance, and the computational fluid dynamics has been an emerging research issue in the studies on the aerosol science and on the multiphase flow science. The difficulty of solving the moment equation arises mainly from the closure of some fractal moment variables which appears in the transform from the non-linear integral-differential population balance equation to the moment equations. Within the Taylor-expansion moment method, the breakage-dominated Taylor-expansion moment equation is first derived here when the symmetric fragmentation mechanism is involved. Due to the high efficiency and the high precision, this proposed moment model is expected to become an important tool for solving population balance equations.

  9. Water balance in the complex mountainous terrain of Bhutan and linkages to land use

    Directory of Open Access Journals (Sweden)

    Ugyen Dorji

    2016-09-01

    Study Focus: Located in the Himalayas with elevation ranging 100–7550 m and with an area equivalent to Switzerland, Bhutan has great biodiversity despite its small area. A monsoon-dominated climate causes generally wet summer and dry winter. Bhutan is highly dependent of climatic conditions for its developmental activities. Using multiple regression analysis we have established models to predict the evapotranspiration (ETo and water balance and test the linkage to vegetation and land cover using meteorological data from 70 weather stations across Bhutan. Temperature-based ETo equations were evaluated in reference to the Penman-Monteith (PM method and a calibrated Hargreaves (H equation was used for computing the ETo. New Hydrological Insights for the Region. The calibrated Hargreaves equation gave good estimates of average daily ETo comparable to the PM ETo. The spatial variation in PM ETo is linked to variation in sunshine hours in summer and temperature in other seasons. Seasonal and annual ETo was mainly affected by elevation and latitude, which is linked to temperature and sunshine duration. Precipitation and water balance correlated positively with the Southern Oscillation Index (SOI while ETo correlated negatively. Our models for predicting ETo and water balances performed clearly better than the global CRU gridded data for Bhutan. A positive water balance is found in broadleaf forest areas and small or negative water balance for coniferous forests.

  10. Development and linealization of materials balance equation generalized for gas deposits associated to the coal

    International Nuclear Information System (INIS)

    Penuela, G; Ordonez, A; Bejarano, A

    1997-01-01

    This equation, was based in 12 similar suppositions to those made by Walsh in its widespread expression for conventional deposits, he parts of the same volumetric consideration and finally the equation is reorganized; the author develops the equation and he gives a series of conclusions with regard to the same one

  11. Baicklund transformation and multiple soliton solutions for the (3+1)-dimensional Jimbo-Miwa equation

    Institute of Scientific and Technical Information of China (English)

    张解放; 吴锋民

    2002-01-01

    We study an approach to constructing multiple soliton solutions of the (3+1)-dimensional nonlinear evolution equation. We take the (3+1)-dimensional Jimbo-Miwa (JM) equation as an example. Using the extended homogeneous balance method, one can find a Backlund transformation to decompose the (3+1)-dimensional JM equation into a linear partial differential equation and two bilinear partial differential equations. Starting from these linear and bilinear partial differential equations, some multiple soliton solutions for the (3+1)-dimensional JM equation are obtained by introducing a class of formal solutions.

  12. Approximate reduction of linear population models governed by stochastic differential equations: application to multiregional models.

    Science.gov (United States)

    Sanz, Luis; Alonso, Juan Antonio

    2017-12-01

    In this work we develop approximate aggregation techniques in the context of slow-fast linear population models governed by stochastic differential equations and apply the results to the treatment of populations with spatial heterogeneity. Approximate aggregation techniques allow one to transform a complex system involving many coupled variables and in which there are processes with different time scales, by a simpler reduced model with a fewer number of 'global' variables, in such a way that the dynamics of the former can be approximated by that of the latter. In our model we contemplate a linear fast deterministic process together with a linear slow process in which the parameters are affected by additive noise, and give conditions for the solutions corresponding to positive initial conditions to remain positive for all times. By letting the fast process reach equilibrium we build a reduced system with a lesser number of variables, and provide results relating the asymptotic behaviour of the first- and second-order moments of the population vector for the original and the reduced system. The general technique is illustrated by analysing a multiregional stochastic system in which dispersal is deterministic and the rate growth of the populations in each patch is affected by additive noise.

  13. Balancing selection and recombination as evolutionary forces caused population genetic variations in golden pheasant MHC class I genes.

    Science.gov (United States)

    Zeng, Qian-Qian; He, Ke; Sun, Dan-Dan; Ma, Mei-Ying; Ge, Yun-Fa; Fang, Sheng-Guo; Wan, Qiu-Hong

    2016-02-18

    pattern indicate that interlocus recombination accounts for much of the allelic variation in IA2. Analysis of the population differentiation implied that homogenous balancing selection plays an important part in maintaining an even distribution of MHC variations. The natural barrier of the Yangtze River and heterogeneous balancing selection might help shape the NYR-SYR genetic structure in golden pheasants.

  14. Inverse Free Iterative Methods for Nonlinear Ill-Posed Operator Equations

    Directory of Open Access Journals (Sweden)

    Ioannis K. Argyros

    2014-01-01

    ill-posed operator equation F(x=y. The proposed method is a modified form of Tikhonov gradient (TIGRA method considered by Ramlau (2003. The regularization parameter is chosen according to the balancing principle considered by Pereverzev and Schock (2005. The error estimate is derived under a general source condition and is of optimal order. Some numerical examples involving integral equations are also given in this paper.

  15. Balanced metrics for vector bundles and polarised manifolds

    DEFF Research Database (Denmark)

    Garcia Fernandez, Mario; Ross, Julius

    2012-01-01

    leads to a Hermitian-Einstein metric on E and a constant scalar curvature Kähler metric in c_1(L). For special values of α, limits of balanced metrics are solutions of a system of coupled equations relating a Hermitian-Einstein metric on E and a Kähler metric in c1(L). For this, we compute the top two......We consider a notion of balanced metrics for triples (X, L, E) which depend on a parameter α, where X is smooth complex manifold with an ample line bundle L and E is a holomorphic vector bundle over X. For generic choice of α, we prove that the limit of a convergent sequence of balanced metrics...

  16. Positive integer solutions of certain diophantine equations

    Indian Academy of Sciences (India)

    BIJAN KUMAR PATEL

    2018-03-19

    Mar 19, 2018 ... integer solutions. They also found all the positive integer solutions of the given equations in terms of Fibonacci and Lucas numbers. Another interesting number sequence which is closely related to the sequence of. Fibonacci numbers is the sequence of balancing numbers. In 1999, Behera et al. [1] intro-.

  17. Linear Discontinuous Expansion Method using the Subcell Balances for Unstructured Geometry SN Transport

    International Nuclear Information System (INIS)

    Hong, Ser Gi; Kim, Jong Woon; Lee, Young Ouk; Kim, Kyo Youn

    2010-01-01

    The subcell balance methods have been developed for one- and two-dimensional SN transport calculations. In this paper, a linear discontinuous expansion method using sub-cell balances (LDEM-SCB) is developed for neutral particle S N transport calculations in 3D unstructured geometrical problems. At present, this method is applied to the tetrahedral meshes. As the name means, this method assumes the linear distribution of the particle flux in each tetrahedral mesh and uses the balance equations for four sub-cells of each tetrahedral mesh to obtain the equations for the four sub-cell average fluxes which are unknowns. This method was implemented in the computer code MUST (Multi-group Unstructured geometry S N Transport). The numerical tests show that this method gives more robust solution than DFEM (Discontinuous Finite Element Method)

  18. The slice balance approach (SBA): a characteristic-based, multiple balance SN approach on unstructured polyhedral meshes

    International Nuclear Information System (INIS)

    Grove, R.E.

    2005-01-01

    The Slice Balance Approach (SBA) is an approach for solving geometrically-complex, neutral-particle transport problems within a multi-group discrete ordinates (S N ) framework. The salient feature is an angle-dependent spatial decomposition. We approximate general surfaces with arbitrary polygonal faces and mesh the geometry with arbitrarily-shaped polyhedral cells. A cell-local spatial decomposition divides cells into angle-dependent slices for each S N direction. This subdivision follows from a characteristic-based view of the transport problem. Most balance-based characteristic methods use it implicitly; we use it explicitly and exploit its properties. Our mathematical approach is a multiple balance approach using exact spatial moments balance equations on cells and slices along with auxiliary relations on slices. We call this the slice balance approach; it is a characteristic-based multiple balance approach. The SBA is intentionally general and can extend differencing schemes to arbitrary 2-D and 3-D meshes. This work contributes to development of general-geometry deterministic transport capability to complement Monte Carlo capability for large, geometrically-complex transport problems. The purpose of this paper is to describe the SBA. We describe the spatial decomposition and mathematical framework and highlight a few interesting properties. We sketch the derivation of two solution schemes, a step characteristic scheme and a diamond-difference-like scheme, to illustrate the approach and we present interesting results for a 2-D problem. (author)

  19. Energy balance in TM-1-MH Tokamak (ohmical heating)

    Science.gov (United States)

    Stoeckel, J.; Koerbel, S.; Kryska, L.; Kopecky, V.; Dadalec, V.; Datlov, J.; Jakubka, K.; Magula, P.; Zacek, F.; Pereverzev, G. V.

    1981-10-01

    Plasma in the TM-1-MH Tokamak was experimentally studied in the parameter range: tor. mg. field B = 1,3 T, plasma current I sub p = 14 kA, electron density N sub E 3.10 to the 19th power cubic meters. The two numerical codes are available for the comparison with experimental data. TOKATA-code solves simplified energy balance equations for electron and ion components. TOKSAS-code solves the detailed energy balance of the ion component.

  20. Changes in Burnout and Satisfaction With Work-Life Balance in Physicians and the General US Working Population Between 2011 and 2014.

    Science.gov (United States)

    Shanafelt, Tait D; Hasan, Omar; Dyrbye, Lotte N; Sinsky, Christine; Satele, Daniel; Sloan, Jeff; West, Colin P

    2015-12-01

    To evaluate the prevalence of burnout and satisfaction with work-life balance in physicians and US workers in 2014 relative to 2011. From August 28, 2014, to October 6, 2014, we surveyed both US physicians and a probability-based sample of the general US population using the methods and measures used in our 2011 study. Burnout was measured using validated metrics, and satisfaction with work-life balance was assessed using standard tools. Of the 35,922 physicians who received an invitation to participate, 6880 (19.2%) completed surveys. When assessed using the Maslach Burnout Inventory, 54.4% (n=3680) of the physicians reported at least 1 symptom of burnout in 2014 compared with 45.5% (n=3310) in 2011 (Pbalance also declined in physicians between 2011 and 2014 (48.5% vs 40.9%; Pbalance were observed by specialty. In contrast to the trends in physicians, minimal changes in burnout or satisfaction with work-life balance were observed between 2011 and 2014 in probability-based samples of working US adults, resulting in an increasing disparity in burnout and satisfaction with work-life balance in physicians relative to the general US working population. After pooled multivariate analysis adjusting for age, sex, relationship status, and hours worked per week, physicians remained at an increased risk of burnout (odds ratio, 1.97; 95% CI, 1.80-2.16; Pbalance (odds ratio, 0.68; 95% CI, 0.62-0.75; Pbalance in US physicians worsened from 2011 to 2014. More than half of US physicians are now experiencing professional burnout. Copyright © 2015 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

  1. Individualism in plant populations: using stochastic differential equations to model individual neighbourhood-dependent plant growth.

    Science.gov (United States)

    Lv, Qiming; Schneider, Manuel K; Pitchford, Jonathan W

    2008-08-01

    We study individual plant growth and size hierarchy formation in an experimental population of Arabidopsis thaliana, within an integrated analysis that explicitly accounts for size-dependent growth, size- and space-dependent competition, and environmental stochasticity. It is shown that a Gompertz-type stochastic differential equation (SDE) model, involving asymmetric competition kernels and a stochastic term which decreases with the logarithm of plant weight, efficiently describes individual plant growth, competition, and variability in the studied population. The model is evaluated within a Bayesian framework and compared to its deterministic counterpart, and to several simplified stochastic models, using distributional validation. We show that stochasticity is an important determinant of size hierarchy and that SDE models outperform the deterministic model if and only if structural components of competition (asymmetry; size- and space-dependence) are accounted for. Implications of these results are discussed in the context of plant ecology and in more general modelling situations.

  2. SUPPORTING STUDENTS’ UNDERSTANDING OF LINEAR EQUATIONS WITH ONE VARIABLE USING ALGEBRA TILES

    Directory of Open Access Journals (Sweden)

    Sari Saraswati

    2016-01-01

    Full Text Available This research aimed to describe how algebra tiles can support students’ understanding of linear equations with one variable. This article is a part of a larger research on learning design of linear equations with one variable using algebra tiles combined with balancing method. Therefore, it will merely discuss one activity focused on how students use the algebra tiles to find a method to solve linear equations with one variable. Design research was used as an approach in this study. It consists of three phases, namely preliminary design, teaching experiment and retrospective analysis. Video registrations, students’ written works, pre-test, post-test, field notes, and interview are technic to collect data. The data were analyzed by comparing the hypothetical learning trajectory (HLT and the actual learning process. The result shows that algebra tiles could supports students’ understanding to find the formal solution of linear equation with one variable.Keywords: linear equation with one variable, algebra tiles, design research, balancing method, HLT DOI: http://dx.doi.org/10.22342/jme.7.1.2814.19-30

  3. Dynamic Response of Inextensible Beams by Improved Energy Balance Method

    DEFF Research Database (Denmark)

    Sfahani, M. G.; Barari, Amin; Omidvar, M.

    2011-01-01

    An improved He's energy balance method (EBM) for solving non-linear oscillatory differential equation using a new trial function is presented. The problem considered represents the governing equations of the non-linear, large-amplitude free vibrations of a slender cantilever beam...... with a rotationally flexible root and carrying a lumped mass at an intermediate position along its span. Based on the simple EBM, the variational integral of the non-linear conservative system is established, and the Fourier series expansion is employed to address the governing algebraic equations. An alternate...

  4. A new balance-of-plant model for the SASSYS-1 LMR systems analysis code

    International Nuclear Information System (INIS)

    Briggs, L.L.

    1991-01-01

    In this paper, a balance-of-plant model is developed for the SASSYS code. This model represents the balance of plant as a network of components. It interfaces with the existing SASSYS code through the water side of the steam generator. The network representation provides a discretization of the mass, momentum, and energy equations and the equation of state and allows a simultaneous solution for the changes in pressure, flow, and enthalpy throughout the waterside system. The model has been tested for several types of transients and been found to perform both accurately and efficiently

  5. Comparison of the performance of the updated Schwartz, combined Schwartz and the Grubb glomerular filtration rate equations in a general pediatric population

    Directory of Open Access Journals (Sweden)

    Alaleh Gheissari

    2014-01-01

    Full Text Available To determine the performance of the updated Schwartz, combined Schwartz and Grubb glomerular filtration rate (GFR equations in a relatively large number of healthy children with no known renal disease, we studied 712 students aged between seven and 18 years from the Isfahan province of Iran by random cluster sampling between 2009 and 2010. Blood investigations included blood urea nitrogen, creatinine and cystatin C. For each participant, GFR was calculated based on the three equations. We used Bland-Altman plots and weighted kappa statistics to compare the performance of the study equations. The mean age of the children was 12.2 ± 2.4 years. A high concordance in estimating GFR (mean difference: 0 ± 12.7 mL/min/1.73 m 2 and a very good agreement in defining chronic kidney disease (CKD and non-CKD individuals (weighted kappa: 0.85; 95% confidence intervals: 0.69-1 were observed between the updated Schwartz and the combined Schwartz equations. Poor agreement was observed between the Grubb equation and two Schwartz equations in estimating GFR and defining CKD. There was no systematic deviation between the updated Schwartz and the combined Schwartz equations in children with normal renal function. The Grubb equation was highly inconsistent with both Schwartz equations in this population. We conclude that the updated Schwartz equation is simpler and more accessible than the combined Schwartz equation in daily clinical practice and CKD screening programs.

  6. Generalized heat-transport equations: parabolic and hyperbolic models

    Science.gov (United States)

    Rogolino, Patrizia; Kovács, Robert; Ván, Peter; Cimmelli, Vito Antonio

    2018-03-01

    We derive two different generalized heat-transport equations: the most general one, of the first order in time and second order in space, encompasses some well-known heat equations and describes the hyperbolic regime in the absence of nonlocal effects. Another, less general, of the second order in time and fourth order in space, is able to describe hyperbolic heat conduction also in the presence of nonlocal effects. We investigate the thermodynamic compatibility of both models by applying some generalizations of the classical Liu and Coleman-Noll procedures. In both cases, constitutive equations for the entropy and for the entropy flux are obtained. For the second model, we consider a heat-transport equation which includes nonlocal terms and study the resulting set of balance laws, proving that the corresponding thermal perturbations propagate with finite speed.

  7. EFFECT OF SPECIFIC BALANCE STRATEGY TRAINING PROGRAMME ON BALANCE IN INSTITUTIONALIZED ELDERLY POPULATION

    OpenAIRE

    Muzaffar Mairaj; Hamdani Nusrat; Walia Shefali

    2015-01-01

    Background: Balance emerges from the interaction of multiple systems that are organized to meet functional task goals and that are constrained by environmental context, but is often compromised with advancing age. At least 30% of older people experience decline in physical activity after entry into residential care. Participation in activity is more difficult for older people because of fear, lack of motivation, depression and poor understanding of the long term benefits of physical activity....

  8. Coupling Algorithms for Calculating Sensitivities of Population Balances

    International Nuclear Information System (INIS)

    Man, P. L. W.; Kraft, M.; Norris, J. R.

    2008-01-01

    We introduce a new class of stochastic algorithms for calculating parametric derivatives of the solution of the space-homogeneous Smoluchowski's coagulation equation. Currently, it is very difficult to produce low variance estimates of these derivatives in reasonable amounts of computational time through the use of stochastic methods. These new algorithms consider a central difference estimator of the parametric derivative which is calculated by evaluating the coagulation equation at two different parameter values simultaneously, and causing variance reduction by maximising the covariance between these. The two different coupling strategies ('Single' and 'Double') have been compared to the case when there is no coupling ('Independent'). Both coupling algorithms converge and the Double coupling is the most 'efficient' algorithm. For the numerical example chosen we obtain a factor of about 100 in efficiency in the best case (small system evolution time and small parameter perturbation).

  9. Seismic performance evaluation of high natural frequency mechanical structure from the viewpoint of energy balance

    International Nuclear Information System (INIS)

    Minagawa, Keisuke; Fujita, Satoshi; Endo, Rokuro; Amemiya, Mitsuhiko

    2009-01-01

    In this study, vibration characteristics of mechanical structure having high natural frequency are investigated from the viewpoint of energy balance. Mechanical structures having high natural frequency in a nuclear power plant are generally designed statically and elastically. However it has been reported that fracture of ordinary piping is produced not by momentary large load but by cumulative fatigue damage. Therefore it is very important to grasp seismic performance dynamically by considering cyclic load. This paper deals with an investigation regarding seismic performance evaluation of high natural frequency mechanical structure. The energy balance equation that is one of valid methods for structural calculation is applied through the investigation. The main feature of the energy balance equation is that it explains accumulated information of motion. Therefore the energy balance equation is adequate for the investigation of the influence of cumulative load such as seismic response. In this paper, vibration experiment and simulation using sinusoidal waves and artificial seismic waves were examined in order to investigate relationship between natural frequency of structure and energy. As a result, we found that input energy decreases with an increase in the natural frequency. (author)

  10. Central-Upwind Schemes for Two-Layer Shallow Water Equations

    KAUST Repository

    Kurganov, Alexander; Petrova, Guergana

    2009-01-01

    We derive a second-order semidiscrete central-upwind scheme for one- and two-dimensional systems of two-layer shallow water equations. We prove that the presented scheme is well-balanced in the sense that stationary steady-state solutions

  11. Partial differential equations mathematical techniques for engineers

    CERN Document Server

    Epstein, Marcelo

    2017-01-01

    This monograph presents a graduate-level treatment of partial differential equations (PDEs) for engineers. The book begins with a review of the geometrical interpretation of systems of ODEs, the appearance of PDEs in engineering is motivated by the general form of balance laws in continuum physics. Four chapters are devoted to a detailed treatment of the single first-order PDE, including shock waves and genuinely non-linear models, with applications to traffic design and gas dynamics. The rest of the book deals with second-order equations. In the treatment of hyperbolic equations, geometric arguments are used whenever possible and the analogy with discrete vibrating systems is emphasized. The diffusion and potential equations afford the opportunity of dealing with questions of uniqueness and continuous dependence on the data, the Fourier integral, generalized functions (distributions), Duhamel's principle, Green's functions and Dirichlet and Neumann problems. The target audience primarily comprises graduate s...

  12. A Balanced Comparison of Object Invariances in Monkey IT Neurons.

    Science.gov (United States)

    Ratan Murty, N Apurva; Arun, Sripati P

    2017-01-01

    Our ability to recognize objects across variations in size, position, or rotation is based on invariant object representations in higher visual cortex. However, we know little about how these invariances are related. Are some invariances harder than others? Do some invariances arise faster than others? These comparisons can be made only upon equating image changes across transformations. Here, we targeted invariant neural representations in the monkey inferotemporal (IT) cortex using object images with balanced changes in size, position, and rotation. Across the recorded population, IT neurons generalized across size and position both stronger and faster than to rotations in the image plane as well as in depth. We obtained a similar ordering of invariances in deep neural networks but not in low-level visual representations. Thus, invariant neural representations dynamically evolve in a temporal order reflective of their underlying computational complexity.

  13. Supporting Students' Understanding of Linear Equations with One Variable Using Algebra Tiles

    Science.gov (United States)

    Saraswati, Sari; Putri, Ratu Ilma Indra; Somakim

    2016-01-01

    This research aimed to describe how algebra tiles can support students' understanding of linear equations with one variable. This article is a part of a larger research on learning design of linear equations with one variable using algebra tiles combined with balancing method. Therefore, it will merely discuss one activity focused on how students…

  14. A Balanced Portfolio Model For Improving Health: Concept And Vermont's Experience.

    Science.gov (United States)

    Hester, James

    2018-04-01

    A successful strategy for improving population health requires acting in several sectors by implementing a portfolio of interventions. The mix of interventions should be both tailored to meet the community's needs and balanced in several dimensions-for example, time frame, level of risk, and target population. One obstacle is finding sustainable financing for both the interventions and the community infrastructure needed. This article first summarizes Vermont's experience as a laboratory for health reform. It then presents a conceptual model for a community-based population health strategy, using a balanced portfolio and diversified funding approaches. The article then reviews Vermont's population health initiative, including an example of a balanced portfolio and lessons learned from the state's experience.

  15. Derivation of integral energy balance for the manotea facility

    Energy Technology Data Exchange (ETDEWEB)

    Pollman, Anthony, E-mail: pollman@nps.edu [Mechanical and Aeronautical Engineering Department, United States Naval Postgraduate School, Monterey, CA 93943 (United States); Marzo, Marino di [Fire Protection Engineering Department, University of Maryland, College Park, MD 20742 (United States)

    2013-12-15

    Highlights: • An integral energy balance was derived for the MANOTEA facility. • A second equation was derived which frames transients in terms of inventory alone. • Both equations were implemented and showed good agreement with experimental data. • The equations capture the physical mechanisms behind MANOTEA transients. • Physical understanding is required in order to properly model these transients with TRACE. - Abstract: Rapid-condensation-induced fluid motion occurs in several nuclear reactor accident sequences, as well as during normal operation. Modeling these events is central to our ability to regulate and ensure safe reactor operations. The UMD-USNA Near One-dimensional Transient Experimental Apparatus (MANOTEA) was constructed in order to create a rapid-condensation dataset for subsequent comparison to TRACE output. This paper outlines a derivation of the energy balance for the facility. A path integral based on mass and energy, rather than fluid mechanical, considerations is derived in order to characterize the physical mechanisms governing MANOTEA transients. This equation is further simplified to obtain an expression that frames transients in term of liquid inventory alone. Using data obtained from an actual transient, the path integral is implemented using three variables (change in liquid inventory, liquid inventory as a function of time, and change in metal temperature) to predict the outcome of a fourth independently measured variable (condenser pressure as a function of time). The implementation yields a very good approximation of the actual data. The inventory equation is also implemented and shows reasonable agreement. These equations, and the physical intuition that they yield, are key to properly characterizing MANOTEA transients and any subsequent modeling efforts.

  16. Rates and time scales of clay-mineral formation by weathering in saprolitic regoliths of the southern Appalachians from geochemical mass balance

    Science.gov (United States)

    Jason R. Price; Michael A. Velbel; Lina C. Patino

    2005-01-01

    Rates of clay formation in three watersheds located at the Coweeta Hydrologic Laboratory, western North Carolina, have been determined from solute flux-based mass balance methods. A system of mass balance equations with enough equations and unknowns to allow calculation of secondary mineral formation rates as well as the more commonly determined primary-...

  17. Harmonic balance approach to the periodic solutions of the (an)harmonic relativistic oscillator

    International Nuclear Information System (INIS)

    Belendez, Augusto; Pascual, Carolina

    2007-01-01

    The first-order harmonic balance method via the first Fourier coefficient is used to construct two approximate frequency-amplitude relations for the relativistic oscillator for which the nonlinearity (anharmonicity) is a relativistic effect due to the time line dilation along the world line. Making a change of variable, a new nonlinear differential equation is obtained and two procedures are used to approximately solve this differential equation. In the first the differential equation is rewritten in a form that does not contain a square-root expression, while in the second the differential equation is solved directly. The approximate frequency obtained using the second procedure is more accurate than the frequency obtained with the first due to the fact that, in the second procedure, application of the harmonic balance method produces an infinite set of harmonics, while in the first procedure only two harmonics are produced. Both approximate frequencies are valid for the complete range of oscillation amplitudes, and excellent agreement of the approximate frequencies with the exact one are demonstrated and discussed. The discrepancy between the first-order approximate frequency obtained by means of the second procedure and the exact frequency never exceeds 1.6%. We also obtained the approximate frequency by applying the second-order harmonic balance method and in this case the relative error is as low 0.31% for all the range of values of amplitude of oscillation A

  18. A comparison of entropy balance and probability weighting methods to generalize observational cohorts to a population: a simulation and empirical example.

    Science.gov (United States)

    Harvey, Raymond A; Hayden, Jennifer D; Kamble, Pravin S; Bouchard, Jonathan R; Huang, Joanna C

    2017-04-01

    We compared methods to control bias and confounding in observational studies including inverse probability weighting (IPW) and stabilized IPW (sIPW). These methods often require iteration and post-calibration to achieve covariate balance. In comparison, entropy balance (EB) optimizes covariate balance a priori by calibrating weights using the target's moments as constraints. We measured covariate balance empirically and by simulation by using absolute standardized mean difference (ASMD), absolute bias (AB), and root mean square error (RMSE), investigating two scenarios: the size of the observed (exposed) cohort exceeds the target (unexposed) cohort and vice versa. The empirical application weighted a commercial health plan cohort to a nationally representative National Health and Nutrition Examination Survey target on the same covariates and compared average total health care cost estimates across methods. Entropy balance alone achieved balance (ASMD ≤ 0.10) on all covariates in simulation and empirically. In simulation scenario I, EB achieved the lowest AB and RMSE (13.64, 31.19) compared with IPW (263.05, 263.99) and sIPW (319.91, 320.71). In scenario II, EB outperformed IPW and sIPW with smaller AB and RMSE. In scenarios I and II, EB achieved the lowest mean estimate difference from the simulated population outcome ($490.05, $487.62) compared with IPW and sIPW, respectively. Empirically, only EB differed from the unweighted mean cost indicating IPW, and sIPW weighting was ineffective. Entropy balance demonstrated the bias-variance tradeoff achieving higher estimate accuracy, yet lower estimate precision, compared with IPW methods. EB weighting required no post-processing and effectively mitigated observed bias and confounding. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Numerical solutions of diffusive logistic equation

    International Nuclear Information System (INIS)

    Afrouzi, G.A.; Khademloo, S.

    2007-01-01

    In this paper we investigate numerically positive solutions of a superlinear Elliptic equation on bounded domains. The study of Diffusive logistic equation continues to be an active field of research. The subject has important applications to population migration as well as many other branches of science and engineering. In this paper the 'finite difference scheme' will be developed and compared for solving the one- and three-dimensional Diffusive logistic equation. The basis of the analysis of the finite difference equations considered here is the modified equivalent partial differential equation approach, developed from many authors these years

  20. Development and application of a unified balancing approach with multiple constraints

    Science.gov (United States)

    Zorzi, E. S.; Lee, C. C.; Giordano, J. C.

    1985-01-01

    The development of a general analytic approach to constrained balancing that is consistent with past influence coefficient methods is described. The approach uses Lagrange multipliers to impose orbit and/or weight constraints; these constraints are combined with the least squares minimization process to provide a set of coupled equations that result in a single solution form for determining correction weights. Proper selection of constraints results in the capability to: (1) balance higher speeds without disturbing previously balanced modes, thru the use of modal trial weight sets; (2) balance off-critical speeds; and (3) balance decoupled modes by use of a single balance plane. If no constraints are imposed, this solution form reduces to the general weighted least squares influence coefficient method. A test facility used to examine the use of the general constrained balancing procedure and application of modal trial weight ratios is also described.

  1. Data-driven discovery of partial differential equations.

    Science.gov (United States)

    Rudy, Samuel H; Brunton, Steven L; Proctor, Joshua L; Kutz, J Nathan

    2017-04-01

    We propose a sparse regression method capable of discovering the governing partial differential equation(s) of a given system by time series measurements in the spatial domain. The regression framework relies on sparsity-promoting techniques to select the nonlinear and partial derivative terms of the governing equations that most accurately represent the data, bypassing a combinatorially large search through all possible candidate models. The method balances model complexity and regression accuracy by selecting a parsimonious model via Pareto analysis. Time series measurements can be made in an Eulerian framework, where the sensors are fixed spatially, or in a Lagrangian framework, where the sensors move with the dynamics. The method is computationally efficient, robust, and demonstrated to work on a variety of canonical problems spanning a number of scientific domains including Navier-Stokes, the quantum harmonic oscillator, and the diffusion equation. Moreover, the method is capable of disambiguating between potentially nonunique dynamical terms by using multiple time series taken with different initial data. Thus, for a traveling wave, the method can distinguish between a linear wave equation and the Korteweg-de Vries equation, for instance. The method provides a promising new technique for discovering governing equations and physical laws in parameterized spatiotemporal systems, where first-principles derivations are intractable.

  2. A New Auto-Baecklund Transformation and Two-Soliton Solution for (3+1)-Dimensional Jimbo-Miwa Equation

    International Nuclear Information System (INIS)

    Liu Chunping; Zhou Ling

    2011-01-01

    By improving the extended homogeneous balance method, a general method is suggested to derive a new auto-Baecklund transformation (BT) for (3+1)-Dimensional Jimbo-Miwa (JM) equation. The auto-BT obtained by using our method only involves one quadratic homogeneity equation written as a bilinear equation. Based on the auto-BT, two-soliton solution of the (3+1)-Dimensional JM equation is obtained. (general)

  3. Modeling of Two-Wheeled Self-Balancing Robot Driven by DC Gearmotors

    Science.gov (United States)

    Frankovský, P.; Dominik, L.; Gmiterko, A.; Virgala, I.; Kurylo, P.; Perminova, O.

    2017-08-01

    This paper is aimed at modelling a two-wheeled self-balancing robot driven by the geared DC motors. A mathematical model consists of two main parts, the model of robot's mechanical structure and the model of the actuator. Linearized equations of motion are derived and the overall model of the two-wheeled self-balancing robot is represented in state-space realization for the purpose of state feedback controller design.

  4. A Well-Balanced and Fully Coupled Noncapacity Model for Dam-Break Flooding

    Directory of Open Access Journals (Sweden)

    Zhiyuan Yue

    2015-01-01

    Full Text Available The last two decades have seen great progress in mathematical modeling of fluvial processes and flooding in terms of either approximation of the physical processes or dealing with the numerical difficulties. Yet attention to simultaneously taking advancements of both aspects is rarely paid. Here a well-balanced and fully coupled noncapacity model is presented of dam-break flooding over erodible beds. The governing equations are based on the complete mass and momentum conservation laws, implying fully coupled interactions between the dam-break flow and sediment transport. A well-balanced Godunov-type finite volume method is used to solve the governing equations, facilitating satisfactory representation of the complex flow phenomena. The well-balanced property is attained by using the divergence form of matrix related to the static force for the bottom slope source term. Existing classical tests, including idealized dam-break flooding over irregular topography and experimental dam-break flooding with/without sediment transport, are numerically simulated, showing a satisfactory quantitative performance of this model.

  5. Reformulation and solution of the master equation for multiple-well chemical reactions.

    Science.gov (United States)

    Georgievskii, Yuri; Miller, James A; Burke, Michael P; Klippenstein, Stephen J

    2013-11-21

    We consider an alternative formulation of the master equation for complex-forming chemical reactions with multiple wells and bimolecular products. Within this formulation the dynamical phase space consists of only the microscopic populations of the various isomers making up the reactive complex, while the bimolecular reactants and products are treated equally as sources and sinks. This reformulation yields compact expressions for the phenomenological rate coefficients describing all chemical processes, i.e., internal isomerization reactions, bimolecular-to-bimolecular reactions, isomer-to-bimolecular reactions, and bimolecular-to-isomer reactions. The applicability of the detailed balance condition is discussed and confirmed. We also consider the situation where some of the chemical eigenvalues approach the energy relaxation time scale and show how to modify the phenomenological rate coefficients so that they retain their validity.

  6. Balance point characterization of interstitial fluid volume regulation.

    Science.gov (United States)

    Dongaonkar, R M; Laine, G A; Stewart, R H; Quick, C M

    2009-07-01

    The individual processes involved in interstitial fluid volume and protein regulation (microvascular filtration, lymphatic return, and interstitial storage) are relatively simple, yet their interaction is exceedingly complex. There is a notable lack of a first-order, algebraic formula that relates interstitial fluid pressure and protein to critical parameters commonly used to characterize the movement of interstitial fluid and protein. Therefore, the purpose of the present study is to develop a simple, transparent, and general algebraic approach that predicts interstitial fluid pressure (P(i)) and protein concentrations (C(i)) that takes into consideration all three processes. Eight standard equations characterizing fluid and protein flux were solved simultaneously to yield algebraic equations for P(i) and C(i) as functions of parameters characterizing microvascular, interstitial, and lymphatic function. Equilibrium values of P(i) and C(i) arise as balance points from the graphical intersection of transmicrovascular and lymph flows (analogous to Guyton's classical cardiac output-venous return curves). This approach goes beyond describing interstitial fluid balance in terms of conservation of mass by introducing the concept of inflow and outflow resistances. Algebraic solutions demonstrate that P(i) and C(i) result from a ratio of the microvascular filtration coefficient (1/inflow resistance) and effective lymphatic resistance (outflow resistance), and P(i) is unaffected by interstitial compliance. These simple algebraic solutions predict P(i) and C(i) that are consistent with reported measurements. The present work therefore presents a simple, transparent, and general balance point characterization of interstitial fluid balance resulting from the interaction of microvascular, interstitial, and lymphatic function.

  7. A comparative study of energy balance among housewives of Ludhiana city.

    Science.gov (United States)

    Kaur, N; Mann, S K; Sidhu, P; Sangha, J K

    1997-01-01

    Energy gap is the main nutritional factor which affects work efficiency in all age groups. The low intake of food results in impaired working efficiency and a low level of vitality. Energy balance was evaluated among 30 healthy, nonpregnant, nonlactating housewives aged 29-40 years drawn from the campus of Punjab Agricultural University and its surrounding areas. The women's mean overall energy intake was 1777 +or- 31 kcal/day, 87% of the ICMR (1990) recommended allowances. Total energy expenditure was measured using a computer-based Nutriguide program of Song et al., Caltrac, FAO/WHO/UNU (1985) equations based upon body weight, and an ICMR (1990) prediction equation also based upon body weight. Statistical analysis identified a significant difference in the energy expenditure measured by all 4 methods except between the FAO/WHO/UNU and ICMR prediction equations. The overall energy balance was maximum and positive according to Caltrac at 4.5 kcal/day. The energy expenditure measured by the Nutriguide, FAO/WHO/UNU, and ICMR methods was significantly correlated to weight. Energy intake was significantly and highly correlated to energy balance in all of the 4 methods. While the subjects were overweight when compared with Life Insurance Corporation of India (1965) Standards, the women's body mass index of 23.11 kg/sq.m was within the normal range.

  8. SASSYS-1 balance-of-plant component models for an integrated plant response

    International Nuclear Information System (INIS)

    Ku, J.-Y.

    1989-01-01

    Models of power plant heat transfer components and rotating machinery have been added to the balance-of-plant model in the SASSYS-1 liquid metal reactor systems analysis code. This work is part of a continuing effort in plant network simulation based on the general mathematical models developed. The models described in this paper extend the scope of the balance-of-plant model to handle non-adiabatic conditions along flow paths. While the mass and momentum equations remain the same, the energy equation now contains a heat source term due to energy transfer across the flow boundary or to work done through a shaft. The heat source term is treated fully explicitly. In addition, the equation of state is rewritten in terms of the quality and separate parameters for each phase. The models are simple enough to run quickly, yet include sufficient detail of dominant plant component characteristics to provide accurate results. 5 refs., 16 figs., 2 tabs

  9. Analytical and numerical treatment of the heat conduction equation obtained via time-fractional distributed-order heat conduction law

    Science.gov (United States)

    Želi, Velibor; Zorica, Dušan

    2018-02-01

    Generalization of the heat conduction equation is obtained by considering the system of equations consisting of the energy balance equation and fractional-order constitutive heat conduction law, assumed in the form of the distributed-order Cattaneo type. The Cauchy problem for system of energy balance equation and constitutive heat conduction law is treated analytically through Fourier and Laplace integral transform methods, as well as numerically by the method of finite differences through Adams-Bashforth and Grünwald-Letnikov schemes for approximation derivatives in temporal domain and leap frog scheme for spatial derivatives. Numerical examples, showing time evolution of temperature and heat flux spatial profiles, demonstrate applicability and good agreement of both methods in cases of multi-term and power-type distributed-order heat conduction laws.

  10. Artificial bee colony algorithm with dynamic multi-population

    Science.gov (United States)

    Zhang, Ming; Ji, Zhicheng; Wang, Yan

    2017-07-01

    To improve the convergence rate and make a balance between the global search and local turning abilities, this paper proposes a decentralized form of artificial bee colony (ABC) algorithm with dynamic multi-populations by means of fuzzy C-means (FCM) clustering. Each subpopulation periodically enlarges with the same size during the search process, and the overlapping individuals among different subareas work for delivering information acting as exploring the search space with diffusion of solutions. Moreover, a Gaussian-based search equation with redefined local attractor is proposed to further accelerate the diffusion of the best solution and guide the search towards potential areas. Experimental results on a set of benchmarks demonstrate the competitive performance of our proposed approach.

  11. Components of Standing Postural Control Evaluated in Pediatric Balance Measures: A Scoping Review.

    Science.gov (United States)

    Sibley, Kathryn M; Beauchamp, Marla K; Van Ooteghem, Karen; Paterson, Marie; Wittmeier, Kristy D

    2017-10-01

    To identify measures of standing balance validated in pediatric populations, and to determine the components of postural control captured in each tool. Electronic searches of MEDLINE, Embase, and CINAHL databases using key word combinations of postural balance/equilibrium, psychometrics/reproducibility of results/predictive value of tests, and child/pediatrics; gray literature; and hand searches. Inclusion criteria were measures with a stated objective to assess balance, with pediatric (≤18y) populations, with at least 1 psychometric evaluation, with at least 1 standing task, with a standardized protocol and evaluation criteria, and published in English. Two reviewers independently identified studies for inclusion. There were 21 measures included. Two reviewers extracted descriptive characteristics, and 2 investigators independently coded components of balance in each measure using a systems perspective for postural control, an established framework for balance in pediatric populations. Components of balance evaluated in measures were underlying motor systems (100% of measures), anticipatory postural control (72%), static stability (62%), sensory integration (52%), dynamic stability (48%), functional stability limits (24%), cognitive influences (24%), verticality (9%), and reactive postural control (0%). Assessing children's balance with valid and comprehensive measures is important for ensuring development of safe mobility and independence with functional tasks. Balance measures validated in pediatric populations to date do not comprehensively assess standing postural control and omit some key components for safe mobility and independence. Existing balance measures, that have been validated in adult populations and address some of the existing gaps in pediatric measures, warrant consideration for validation in children. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  12. Combined solitary-wave solution for coupled higher-order nonlinear Schroedinger equations

    International Nuclear Information System (INIS)

    Tian Jinping; Tian Huiping; Li Zhonghao; Zhou Guosheng

    2004-01-01

    Coupled nonlinear Schroedinger equations model several interesting physical phenomena. We used a trigonometric function transform method based on a homogeneous balance to solve the coupled higher-order nonlinear Schroedinger equations. We obtained four pairs of exact solitary-wave solutions including a dark and a bright-soliton pair, a bright- and a dark-soliton pair, a bright- and a bright-soliton pair, and the last pair, a combined bright-dark-soliton pair

  13. Frequency-Weighted Balancing Related Controller Reduction

    OpenAIRE

    Varga, Andras; Anderson, Brian D.O.

    2002-01-01

    The efficient solution of a class of controller approximation problems by using frequency-weighted balancing related model reduction approaches is considered. It is shown that for certain standard performance and stability enforcing frequency-weights, the computation of the frequency-weighted controllability and observability grammians can be done by solving reduced order Lyapunov equations regardless the controller itself is stable or unstable. The new approach can be used in conjunction wit...

  14. On Pell, Pell-Lucas, and balancing numbers.

    Science.gov (United States)

    Karadeniz Gözeri, Gül

    2018-01-01

    In this paper, we derive some identities on Pell, Pell-Lucas, and balancing numbers and the relationships between them. We also deduce some formulas on the sums, divisibility properties, perfect squares, Pythagorean triples involving these numbers. Moreover, we obtain the set of positive integer solutions of some specific Pell equations in terms of the integer sequences mentioned in the text.

  15. A comparison of deflation and the balancing Neumann-Neumann preconditioner

    NARCIS (Netherlands)

    Nabben, R.; Vuik, C.

    2004-01-01

    In this paper we compare various preconditioners for the numerical solution of partial differential equations. We compare the well-known balancing Neumann Neumann preconditioner used in domain decomposition methods with a so-called deflation preconditioner. We prove that the effective condition

  16. Modeling of Two-Wheeled Self-Balancing Robot Driven by DC Gearmotors

    Directory of Open Access Journals (Sweden)

    Frankovský P.

    2017-08-01

    Full Text Available This paper is aimed at modelling a two-wheeled self-balancing robot driven by the geared DC motors. A mathematical model consists of two main parts, the model of robot’s mechanical structure and the model of the actuator. Linearized equations of motion are derived and the overall model of the two-wheeled self-balancing robot is represented in state-space realization for the purpose of state feedback controller design.

  17. The local quantum-mechanical momentum balance and its consequencies

    International Nuclear Information System (INIS)

    Zieche, P.; Diener, G.; Graafenstejn, J.; Kaschner, R.; Nielsen, O.H.

    1988-01-01

    Many-electron systems are considered within Born-Oppenheimer approximation. The balance equation is derived; its first application concerns force sum rules, involving alternative possibilities for the calculation of relaxation forces. An extended crystal with force-free bulk atoms but under a non-vanishing stress is considered

  18. Kin Selection - Mutation Balance

    DEFF Research Database (Denmark)

    Dyken, J. David Van; Linksvayer, Timothy Arnold; Wade, Michael J.

    2011-01-01

    selection-mutation balance, which provides an evolutionary null hypothesis for the statics and dynamics of cheating. When social interactions have linear fitness effects and Hamilton´s rule is satisfied, selection is never strong enough to eliminate recurrent cheater mutants from a population, but cheater...

  19. Does an exercise programme integrating the Nintendo Wii-Fit Balance Board improve balance in ambulatory children with cerebral palsy?

    OpenAIRE

    Cooper, T.; Williams, Jonathan M.

    2017-01-01

    Background: Cerebral palsy is a common childhood movement disorder with balance impairment a common complaint. Active video games such as the Nintendo Wii-Fit have been found to be a valuable therapeutic tool, enjoyed by a variety of populations including children with CP, but a synthesis of the research investigating its specific use for balance in children with CP has yet to be conducted.\\ud \\ud Objectives: To determine the effectiveness of a Nintendo Wii-Fit Balance board programme in impr...

  20. Calcium Balance in Chronic Kidney Disease.

    Science.gov (United States)

    Hill Gallant, Kathleen M; Spiegel, David M

    2017-06-01

    The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

  1. Harmonic balancing approach to nonlinear oscillations of a punctual charge in the electric field of charged ring

    International Nuclear Information System (INIS)

    Belendez, A.; Fernandez, E.; Rodes, J.J.; Fuentes, R.; Pascual, I.

    2009-01-01

    The harmonic balance method is used to construct approximate frequency-amplitude relations and periodic solutions to an oscillating charge in the electric field of a ring. By combining linearization of the governing equation with the harmonic balance method, we construct analytical approximations to the oscillation frequencies and periodic solutions for the oscillator. To solve the nonlinear differential equation, firstly we make a change of variable and secondly the differential equation is rewritten in a form that does not contain the square-root expression. The approximate frequencies obtained are valid for the complete range of oscillation amplitudes and excellent agreement of the approximate frequencies and periodic solutions with the exact ones are demonstrated and discussed

  2. Equation-free modeling unravels the behavior of complex ecological systems

    Science.gov (United States)

    DeAngelis, Donald L.; Yurek, Simeon

    2015-01-01

    Ye et al. (1) address a critical problem confronting the management of natural ecosystems: How can we make forecasts of possible future changes in populations to help guide management actions? This problem is especially acute for marine and anadromous fisheries, where the large interannual fluctuations of populations, arising from complex nonlinear interactions among species and with varying environmental factors, have defied prediction over even short time scales. The empirical dynamic modeling (EDM) described in Ye et al.’s report, the latest in a series of papers by Sugihara and his colleagues, offers a promising quantitative approach to building models using time series to successfully project dynamics into the future. With the term “equation-free” in the article title, Ye et al. (1) are suggesting broader implications of their approach, considering the centrality of equations in modern science. From the 1700s on, nature has been increasingly described by mathematical equations, with differential or difference equations forming the basic framework for describing dynamics. The use of mathematical equations for ecological systems came much later, pioneered by Lotka and Volterra, who showed that population cycles might be described in terms of simple coupled nonlinear differential equations. It took decades for Lotka–Volterra-type models to become established, but the development of appropriate differential equations is now routine in modeling ecological dynamics. There is no question that the injection of mathematical equations, by forcing “clarity and precision into conjecture” (2), has led to increased understanding of population and community dynamics. As in science in general, in ecology equations are a key method of communication and of framing hypotheses. These equations serve as compact representations of an enormous amount of empirical data and can be analyzed by the powerful methods of mathematics.

  3. The village/commune safety policy and HIV prevention efforts among key affected populations in Cambodia: finding a balance

    Directory of Open Access Journals (Sweden)

    Thomson Nick

    2012-07-01

    Full Text Available Abstract The Village/Commune Safety Policy was launched by the Ministry of Interior of the Kingdom of Cambodia in 2010 and, due to a priority focus on “cleaning the streets”, has created difficulties for HIV prevention programs attempting to implement programs that work with key affected populations including female sex workers and people who inject drugs. The implementation of the policy has forced HIV program implementers, the UN and various government counterparts to explore and develop collaborative ways of delivering HIV prevention services within this difficult environment. The following case study explores some of these efforts and highlights the promising development of a Police Community Partnership Initiative that it is hoped will find a meaningful balance between the Village/Commune Safety Policy and HIV prevention efforts with key affected populations in Cambodia.

  4. 16 reference population equations using peak expiratory flow meters

    African Journals Online (AJOL)

    DR. AMINU

    equations in current use are based on linear statistical models which are subject to change and they did not ... assess risks of surgery and to assist in evaluations performed ... identify and quantify pulmonary involvement incases of asthma.

  5. DNA Dynamics Studied Using the Homogeneous Balance Method

    International Nuclear Information System (INIS)

    Zayed, E. M. E.; Arnous, A. H.

    2012-01-01

    We employ the homogeneous balance method to construct the traveling waves of the nonlinear vibrational dynamics modeling of DNA. Some new explicit forms of traveling waves are given. It is shown that this method provides us with a powerful mathematical tool for solving nonlinear evolution equations in mathematical physics. Strengths and weaknesses of the proposed method are discussed. (general)

  6. VMOMS: a computer code for finding moment solutions to the Grad-Shafranov equation

    International Nuclear Information System (INIS)

    Lao, L.L.; Wieland, R.M.; Houlberg, W.A.; Hirshman, S.P.

    1982-02-01

    A code VMOMS is described which finds approximate solutions to the Grad-Shafranov equation describing scalar pressure-balance equilibria for axisymmetric tokamak plasmas. A Fourier series expansion of the flux surface coordinates (R,Z) is made in terms of two new coordinates (rho, theta), and the resulting equation is conveniently reduced to a system of ordinary differential equations (ODE's) using a variational principle. The solution of these simple equations with pressure and current as driving functions, yields, in principle, a complete description of the equilibrium. Complete axisymmetry is assumed, as well as up-down symmetry about the toroidal midplane

  7. Estimation of air-water gas exchange coefficient in a shallow lagoon based on 222Rn mass balance.

    Science.gov (United States)

    Cockenpot, S; Claude, C; Radakovitch, O

    2015-05-01

    The radon-222 mass balance is now commonly used to quantify water fluxes due to Submarine Groundwater Discharge (SGD) in coastal areas. One of the main loss terms of this mass balance, the radon evasion to the atmosphere, is based on empirical equations. This term is generally estimated using one among the many empirical equations describing the gas transfer velocity as a function of wind speed that have been proposed in the literature. These equations were, however, mainly obtained from areas of deep water and may be less appropriate for shallow areas. Here, we calculate the radon mass balance for a windy shallow coastal lagoon (mean depth of 6m and surface area of 1.55*10(8) m(2)) and use these data to estimate the radon loss to the atmosphere and the corresponding gas transfer velocity. We present new equations, adapted to our shallow water body, to express the gas transfer velocity as a function of wind speed at 10 m height (wind range from 2 to 12.5 m/s). When compared with those from the literature, these equations fit particularly well with the one of Kremer et al. (2003). Finally, we emphasize that some gas transfer exchange may always occur, even for conditions without wind. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Delay effects in the human sensory system during balancing.

    Science.gov (United States)

    Stepan, Gabor

    2009-03-28

    Mechanical models of human self-balancing often use the Newtonian equations of inverted pendula. While these mathematical models are precise enough on the mechanical side, the ways humans balance themselves are still quite unexplored on the control side. Time delays in the sensory and motoric neural pathways give essential limitations to the stabilization of the human body as a multiple inverted pendulum. The sensory systems supporting each other provide the necessary signals for these control tasks; but the more complicated the system is, the larger delay is introduced. Human ageing as well as our actual physical and mental state affects the time delays in the neural system, and the mechanical structure of the human body also changes in a large range during our lives. The human balancing organ, the labyrinth, and the vision system essentially adapted to these relatively large time delays and parameter regions occurring during balancing. The analytical study of the simplified large-scale time-delayed models of balancing provides a Newtonian insight into the functioning of these organs that may also serve as a basis to support theories and hypotheses on balancing and vision.

  9. Virtual reality balance training for elderly: Similar skiing games elicit different challenges in balance training.

    Science.gov (United States)

    de Vries, Aijse W; Faber, Gert; Jonkers, Ilse; Van Dieen, Jaap H; Verschueren, Sabine M P

    2018-01-01

    Virtual Reality (VR) balance training may have advantages over regular exercise training in older adults. However, results so far are conflicting potentially due to the lack of challenge imposed by the movements in those games. Therefore, the aim of this study was to assess to which extent two similar skiing games challenge balance, as reflected in center of mass (COM) movements relative to their Functional Limits of Stability (FLOS). Thirty young and elderly participants performed two skiing games, one on the Wii Balance board (Wiiski), which uses a force plate, and one with the Kinect sensor (Kinski), which performs motion tracking. During gameplay, kinematics were captured using seven opto-electronical cameras. FLOS were obtained for eight directions. The influence of games and trials on COM displacement in each of the eight directions, and maximal COM speed, were tested with Generalized Estimated Equations. In all directions with anterior and medio-lateral, but not with a posterior component, subjects showed significantly larger maximal %FLOS displacements during the Kinski game than during the Wiiski game. Furthermore, maximal COM displacement, and COM speed in Kinski remained similar or increased over trials, whereas for Wiiski it decreased. Our results show the importance of assessing the movement challenge in games used for balance training. Similar games impose different challenges, with the control sensors and their gain settings playing an important role. Furthermore, adaptations led to a decrease in challenge in Wiiski, which might limit the effectiveness of the game as a balance-training tool. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. The modified simple equation method for solving some fractional ...

    Indian Academy of Sciences (India)

    ... and processes in various areas of natural science. Thus, many effective and powerful methods have been established and improved. In this study, we establish exact solutions of the time fractional biological population model equation and nonlinearfractional Klein–Gordon equation by using the modified simple equation ...

  11. A nondissipative simulation method for the drift kinetic equation

    International Nuclear Information System (INIS)

    Watanabe, Tomo-Hiko; Sugama, Hideo; Sato, Tetsuya

    2001-07-01

    With the aim to study the ion temperature gradient (ITG) driven turbulence, a nondissipative kinetic simulation scheme is developed and comprehensively benchmarked. The new simulation method preserving the time-reversibility of basic kinetic equations can successfully reproduce the analytical solutions of asymmetric three-mode ITG equations which are extended to provide a more general reference for benchmarking than the previous work [T.-H. Watanabe, H. Sugama, and T. Sato: Phys. Plasmas 7 (2000) 984]. It is also applied to a dissipative three-mode system, and shows a good agreement with the analytical solution. The nondissipative simulation result of the ITG turbulence accurately satisfies the entropy balance equation. Usefulness of the nondissipative method for the drift kinetic simulations is confirmed in comparisons with other dissipative schemes. (author)

  12. Biofeedback for training balance and mobility tasks in older populations : a systematic review

    NARCIS (Netherlands)

    Zijlstra, Agnes; Mancini, Martina; Chiari, Lorenzo; Zijlstra, Wiebren

    2010-01-01

    Context: An effective application of biofeedback for interventions in older adults with balance and mobility disorders may be compromised due to co-morbidity. Objective: To evaluate the feasibility and the effectiveness of biofeedback-based training of balance and/or mobility in older adults. Data

  13. Nonlinear wave equation in frequency domain: accurate modeling of ultrafast interaction in anisotropic nonlinear media

    DEFF Research Database (Denmark)

    Guo, Hairun; Zeng, Xianglong; Zhou, Binbin

    2013-01-01

    We interpret the purely spectral forward Maxwell equation with up to third-order induced polarizations for pulse propagation and interactions in quadratic nonlinear crystals. The interpreted equation, also named the nonlinear wave equation in the frequency domain, includes quadratic and cubic...... nonlinearities, delayed Raman effects, and anisotropic nonlinearities. The full potential of this wave equation is demonstrated by investigating simulations of solitons generated in the process of ultrafast cascaded second-harmonic generation. We show that a balance in the soliton delay can be achieved due...

  14. Modeling and Prediction Using Stochastic Differential Equations

    DEFF Research Database (Denmark)

    Juhl, Rune; Møller, Jan Kloppenborg; Jørgensen, John Bagterp

    2016-01-01

    Pharmacokinetic/pharmakodynamic (PK/PD) modeling for a single subject is most often performed using nonlinear models based on deterministic ordinary differential equations (ODEs), and the variation between subjects in a population of subjects is described using a population (mixed effects) setup...... deterministic and can predict the future perfectly. A more realistic approach would be to allow for randomness in the model due to e.g., the model be too simple or errors in input. We describe a modeling and prediction setup which better reflects reality and suggests stochastic differential equations (SDEs...

  15. Balance control in elderly people with osteoporosis

    Directory of Open Access Journals (Sweden)

    Wei-Li Hsu

    2014-06-01

    Full Text Available Osteoporosis is a prevalent health concern among older adults and is associated with an increased risk of falls that incur fracture, injury, or mortality. Identifying the risk factors of falls within this population is essential for the development of effective regimes for fall prevention. Studies have shown that muscle quality and good posture alignments are critical for balance control in elderly individuals. People with osteoporosis often have muscle weakness and increased spine kyphosis leading to vertebral fractures and poor balance control, or even falls. Therefore, improving muscle quality, strengthening weak muscles, and correcting postural alignment are essential elements for the prevention of falls and fractures in older adults with osteoporosis. This review reports the necessary information regarding the critical factors of balance control in older adults with osteoporosis, as well as testing the clinical innovations of exercise training to improve the long-term prognosis of osteoporosis in this vulnerable population.

  16. A Derivation of Source-based Kinetics Equation with Time Dependent Fission Kernel for Reactor Transient Analyses

    International Nuclear Information System (INIS)

    Kim, Song Hyun; Woo, Myeong Hyun; Shin, Chang Ho; Pyeon, Cheol Ho

    2015-01-01

    In this study, a new balance equation to overcome the problems generated by the previous methods is proposed using source-based balance equation. And then, a simple problem is analyzed with the proposed method. In this study, a source-based balance equation with the time dependent fission kernel was derived to simplify the kinetics equation. To analyze the partial variations of reactor characteristics, two representative methods were introduced in previous studies; (1) quasi-statics method and (2) multipoint technique. The main idea of quasistatics method is to use a low-order approximation for large integration times. To realize the quasi-statics method, first, time dependent flux is separated into the shape and amplitude functions, and shape function is calculated. It is noted that the method has a good accuracy; however, it can be expensive as a calculation cost aspect because the shape function should be fully recalculated to obtain accurate results. To improve the calculation efficiency, multipoint method was proposed. The multipoint method is based on the classic kinetics equation with using Green's function to analyze the flight probability from region r' to r. Those previous methods have been used to analyze the reactor kinetics analysis; however, the previous methods can have some limitations. First, three group variables (r g , E g , t g ) should be considered to solve the time dependent balance equation. This leads a big limitation to apply large system problem with good accuracy. Second, the energy group neutrons should be used to analyze reactor kinetics problems. In time dependent problem, neutron energy distribution can be changed at different time. It can affect the change of the group cross section; therefore, it can lead the accuracy problem. Third, the neutrons in a space-time region continually affect the other space-time regions; however, it is not properly considered in the previous method. Using birth history of the neutron sources

  17. Remarks on the chemical Fokker-Planck and Langevin equations: Nonphysical currents at equilibrium.

    Science.gov (United States)

    Ceccato, Alessandro; Frezzato, Diego

    2018-02-14

    The chemical Langevin equation and the associated chemical Fokker-Planck equation are well-known continuous approximations of the discrete stochastic evolution of reaction networks. In this work, we show that these approximations suffer from a physical inconsistency, namely, the presence of nonphysical probability currents at the thermal equilibrium even for closed and fully detailed-balanced kinetic schemes. An illustration is given for a model case.

  18. MICB gene diversity and balancing selection on its promoter region in Yao population in southern China.

    Science.gov (United States)

    Chen, Xiang; Liu, Xuexiang; Wei, Xiaomou; Meng, Yuming; Liu, Limin; Qin, Shini; Liu, Yanyu; Dai, Shengming

    2016-12-01

    To comprehensively examine the MICB gene polymorphism and identify its differences in Chinese Yao population from other ethnic groups, we investigated the polymorphism in the 5'-upstream regulation region (5'-URR), coding region (exons 2-4), and the 3'-untranslated region (3'-UTR) of MICB gene by using PCR-SBT method in 125 healthy unrelated Yao individuals in Guangxi Zhuang Autonomous Region. Higher polymorphism was observed in the 5'-URR, nine single nucleotide polymorphisms (SNPs) and a two base pairs deletion at position -139/-138 were found in our study. Only five different variation sites, however, were detected in exons 2-4 and three were observed in the 3'-UTR. The minor allele frequencies of all variants were greater than 5%, except for rs3828916, rs3131639, rs45627734, rs113620316, rs779737471, and the variation at position +11803 in the 3'-UTR. The first nine SNPs of 5'-URR and rs1065075, rs1051788 of the coding region showed significant linkage disequilibrium with each other. Ten different MICB extended haplotypes (EH) encompassing the 5'-URR, exons 2-4, and 3'-UTR were found in this population, and the most frequent was EH1 (23.2%). We provided several evidences for balancing selection effect on the 5'-URR of MICB gene in Yao population. Copyright © 2016 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

  19. Validity of the Nintendo Wii® balance board for the assessment of standing balance in Parkinson's disease.

    Science.gov (United States)

    Holmes, Jeffrey D; Jenkins, Mary E; Johnson, Andrew M; Hunt, Michael A; Clark, Ross A

    2013-04-01

    Impaired postural stability places individuals with Parkinson's at an increased risk for falls. Given the high incidence of fall-related injuries within this population, ongoing assessment of postural stability is important. To evaluate the validity of the Nintendo Wii(®) balance board as a measurement tool for the assessment of postural stability in individuals with Parkinson's. Twenty individuals with Parkinson's participated. Subjects completed testing on two balance tasks with eyes open and closed on a Wii(®) balance board and biomechanical force platform. Bland-Altman plots and a two-way, random-effects, single measure intraclass correlation coefficient model were used to assess concurrent validity of centre-of-pressure data. Concurrent validity was demonstrated to be excellent across balance tasks (intraclass correlation coefficients = 0.96, 0.98, 0.92, 0.94). This study suggests that the Wii(®) balance board is a valid tool for the quantification of postural stability among individuals with Parkinson's.

  20. Top 10 Research Questions Related to Energy Balance

    Science.gov (United States)

    Shook, Robin P.; Hand, Gregory A.; Blair, Steven N.

    2014-01-01

    Obesity is the result of a mismatch between the amount of calories consumed and the amount of calories expended during an extended period of time. This relationship is described by the energy balance equation, which states the rate of change in energy storage depots in the body are equal to the rate of energy intake minus the rate of energy…

  1. Master equations for degenerate systems: electron radiative cascade in a Coulomb potential

    International Nuclear Information System (INIS)

    Uskov, D B; Pratt, R H

    2004-01-01

    We examine the effects of degeneracy and its lifting for the problem of electron radiative cascade, described by master equations of the Lindblad form (quantum optical master equations). A weak external field approximation is used to study the resulting gradual transformation of cascade dynamics between degenerate and non-degenerate forms. Exploiting the spherical symmetry properties of the system we demonstrate significant difference between perturbations commuting with angular momentum and perturbations breaking the spherical symmetry, such as a homogeneous external field. We discuss the possibility and the general approach for reduction of the Lindblad master equations in the case of spectral degeneracy to the Pauli balance equations. This determines the appropriate choice of basis as, for example, spherical or parabolic

  2. Regression Analysis and Calibration Recommendations for the Characterization of Balance Temperature Effects

    Science.gov (United States)

    Ulbrich, N.; Volden, T.

    2018-01-01

    Analysis and use of temperature-dependent wind tunnel strain-gage balance calibration data are discussed in the paper. First, three different methods are presented and compared that may be used to process temperature-dependent strain-gage balance data. The first method uses an extended set of independent variables in order to process the data and predict balance loads. The second method applies an extended load iteration equation during the analysis of balance calibration data. The third method uses temperature-dependent sensitivities for the data analysis. Physical interpretations of the most important temperature-dependent regression model terms are provided that relate temperature compensation imperfections and the temperature-dependent nature of the gage factor to sets of regression model terms. Finally, balance calibration recommendations are listed so that temperature-dependent calibration data can be obtained and successfully processed using the reviewed analysis methods.

  3. Periodic Solutions, Eigenvalue Curves, and Degeneracy of the Fractional Mathieu Equation

    International Nuclear Information System (INIS)

    Parra-Hinojosa, A; Gutiérrez-Vega, J C

    2016-01-01

    We investigate the eigenvalue curves, the behavior of the periodic solutions, and the orthogonality properties of the Mathieu equation with an additional fractional derivative term using the method of harmonic balance. The addition of the fractional derivative term breaks the hermiticity of the equation in such a way that its eigenvalues need not be real nor its eigenfunctions orthogonal. We show that for a certain choice of parameters the eigenvalue curves reveal the appearance of degenerate eigenvalues. We offer a detailed discussion of the matrix representation of the differential operator corresponding to the fractional Mathieu equation, as well as some numerical examples of its periodic solutions. (paper)

  4. Regular and chaotic behaviors of plasma oscillations modeled by a modified Duffing equation

    International Nuclear Information System (INIS)

    Enjieu Kadji, H.G.; Chabi Orou, J.B.; Woafo, P.; Abdus Salam International Centre for Theoretical Physics, Trieste

    2005-07-01

    The regular and chaotic behavior of plasma oscillations governed by a modified Duffing equation is studied. The plasma oscillations are described by a nonlinear differential equation of the form x + w 0 2 x + βx 2 + αx 3 = 0 which is similar to a Duffing equation. By focusing on the quadratic term, which is mainly the term modifying the Duffing equation, the harmonic balance method and the fourth order Runge-Kutta algorithm are used to derive regular and chaotic motions respectively. A strong chaotic behavior exhibited by the system in that event when the system is subjected to an external periodic forcing oscillation is reported as β varies. (author)

  5. Climate Modeling in the Calculus and Differential Equations Classroom

    Science.gov (United States)

    Kose, Emek; Kunze, Jennifer

    2013-01-01

    Students in college-level mathematics classes can build the differential equations of an energy balance model of the Earth's climate themselves, from a basic understanding of the background science. Here we use variable albedo and qualitative analysis to find stable and unstable equilibria of such a model, providing a problem or perhaps a…

  6. Formal derivation of a 6 equation macro scale model for two-phase flows - link with the 4 equation macro scale model implemented in Flica 4; Etablissement formel d'un modele diphasique macroscopique a 6 equations - lien avec le modele macroscopique a 4 equations flica 4

    Energy Technology Data Exchange (ETDEWEB)

    Gregoire, O

    2008-07-01

    In order to simulate nuclear reactor cores, we presently use the 4 equation model implemented within FLICA4 code. This model is complemented with 2 algebraic closures for thermal disequilibrium and relative velocity between phases. Using such closures, means an 'a priori' knowledge of flows calculated in order to ensure that modelling assumptions apply. In order to improve the degree of universality to our macroscopic modelling, we propose in the report to derive a more general 6 equation model (balance equations for mass, momentum and enthalpy for each phase) for 2-phase flows. We apply the up-scaling procedure (Whitaker, 1999) classically used in porous media analysis to the statistically averaged equations (Aniel-Buchheit et al., 2003). By doing this, we apply the double-averaging procedure (Pedras and De Lemos, 2001 and Pinson et al. 2006): statistical and spatial averages. Then, using weighted averages (analogous to Favre's average) we extend the spatial averaging concept to variable density and 2-phase flows. This approach allows the global recovering of the structure of the systems of equations implemented in industrial codes. Supplementary contributions, such as dispersion, are also highlighted. Mechanical and thermal exchanges between solids and fluid are formally derived. Then, thanks to realistic simplifying assumptions, we show how it is possible to derive the original 4 equation model from the full 6 equation model. (author)

  7. Local and global particle and power balance in large area capacitive discharges

    International Nuclear Information System (INIS)

    Cho, Suwon; Lieberman, M A

    2003-01-01

    Large area radio frequency (rf) capacitive discharges have attracted recent interest for materials etching and deposition on large area substrates. A distinguishing feature is that the radial distribution of the absorbed rf power in these discharges depends on the rf voltage across the plates, independent of the radial variation of the plasma density n(r). A reduced set of steady-state fluid equations has been used to investigate the radial variation of n and electron temperature T e . The derived equations are shown to be invariant with respect to pL and pR, where p is the pressure, L is the plate separation and R is the discharge radius, and can be further reduced to the equations of the usual global balance model when R ε , the energy relaxation length. In this limit, the ionization frequency and T e are essentially independent of radius and n can be approximately described by the usual radial profile of a zeroth-order Bessel function. When R≥λ ε , n and T e are predominantly determined by local particle and power balance, and the n and T e radial profiles are flat over most of the volume except near the radial boundary, where n falls and T e rises to account for the increased losses at the boundary. The scale length of the edge density variation in the local balance regime is shown to be proportional to the energy relaxation length

  8. Coarse-grained forms for equations describing the microscopic motion of particles in a fluid.

    Science.gov (United States)

    Das, Shankar P; Yoshimori, Akira

    2013-10-01

    Exact equations of motion for the microscopically defined collective density ρ(x,t) and the momentum density ĝ(x,t) of a fluid have been obtained in the past starting from the corresponding Langevin equations representing the dynamics of the fluid particles. In the present work we average these exact equations of microscopic dynamics over the local equilibrium distribution to obtain stochastic partial differential equations for the coarse-grained densities with smooth spatial and temporal dependence. In particular, we consider Dean's exact balance equation for the microscopic density of a system of interacting Brownian particles to obtain the basic equation of the dynamic density functional theory with noise. Our analysis demonstrates that on thermal averaging the dependence of the exact equations on the bare interaction potential is converted to dependence on the corresponding thermodynamic direct correlation functions in the coarse-grained equations.

  9. Targets of balancing selection in the human genome

    DEFF Research Database (Denmark)

    Andrés, Aida M; Hubisz, Melissa J; Indap, Amit

    2009-01-01

    Balancing selection is potentially an important biological force for maintaining advantageous genetic diversity in populations, including variation that is responsible for long-term adaptation to the environment. By serving as a means to maintain genetic variation, it may be particularly relevant...... to maintaining phenotypic variation in natural populations. Nevertheless, its prevalence and specific targets in the human genome remain largely unknown. We have analyzed the patterns of diversity and divergence of 13,400 genes in two human populations using an unbiased single-nucleotide polymorphism data set......, a genome-wide approach, and a method that incorporates demography in neutrality tests. We identified an unbiased catalog of genes with signatures of long-term balancing selection, which includes immunity genes as well as genes encoding keratins and membrane channels; the catalog also shows enrichment...

  10. Moment equation approach to neoclassical transport theory

    International Nuclear Information System (INIS)

    Hirshman, S.P.

    1978-01-01

    The neoclassical cross-field fluxes for a toroidally confined, axisymmetric plasma are calculated in terms of the thermodynamic forces from the fluid continuity and momentum balance equations. This macroscopic formulation of neoclassical transport theory unifies the numerous complex expressions for the transport coefficients, previously obtained by solving the Fokker--Planck equation, and elucidates their physical basis. In the large aspect ratio limit, the continuous transition in the scaling of the diffusion coefficient throughout various collisionality regimes is shown to depend on the ratio of parallel viscosity coefficients of the plasma species. Comparison of the present results with the kinetic theory expressions for the neoclassical fluxes determines the parallel viscosity coefficients for a multispecies plasma in the long-mean-free-path regime

  11. A well-balanced meshless tsunami propagation and inundation model

    Science.gov (United States)

    Brecht, Rüdiger; Bihlo, Alexander; MacLachlan, Scott; Behrens, Jörn

    2018-05-01

    We present a novel meshless tsunami propagation and inundation model. We discretize the nonlinear shallow-water equations using a well-balanced scheme relying on radial basis function based finite differences. For the inundation model, radial basis functions are used to extrapolate the dry region from nearby wet points. Numerical results against standard one- and two-dimensional benchmarks are presented.

  12. Properties of quantum Markovian master equations

    International Nuclear Information System (INIS)

    Gorini, V.; Frigerio, A.; Verri, M.; Kossakowski, A.; Sudarshan, E.C.G.

    1976-11-01

    An essentially self-contained account is given of some general structural properties of the dynamics of quantum open Markovian systems. Some recent results regarding the problem of the classification of quantum Markovian master equations and the limiting conditions under which the dynamical evolution of a quantum open system obeys an exact semigroup law (weak coupling limit and singular coupling limit are reviewed). A general form of quantum detailed balance and its relation to thermal relaxation and to microreversibility is discussed

  13. Global evapotranspiration over the past three decades: estimation based on the water balance equation combined with empirical models

    International Nuclear Information System (INIS)

    Zeng Zhenzhong; Piao Shilong; Yin Guodong; Peng Shushi; Lin Xin; Ciais, Philippe; Myneni, Ranga B

    2012-01-01

    We applied a land water mass balance equation over 59 major river basins during 2003–9 to estimate evapotranspiration (ET), using as input terrestrial water storage anomaly (TWSA) data from the GRACE satellites, precipitation and in situ runoff measurements. We found that the terrestrial water storage change cannot be neglected in the estimation of ET on an annual time step, especially in areas with relatively low ET values. We developed a spatial regression model of ET by integrating precipitation, temperature and satellite-derived normalized difference vegetation index (NDVI) data, and used this model to extrapolate the spatio-temporal patterns of changes in ET from 1982 to 2009. We found that the globally averaged land ET is about 604 mm yr −1 with a range of 558–650 mm yr −1 . From 1982 to 2009, global land ET was found to increase at a rate of 1.10 mm yr −2 , with the Amazon regions and Southeast Asia showing the highest ET increasing trend. Further analyses, however, show that the increase in global land ET mainly occurred between the 1980s and the 1990s. The trend over the 2000s, its magnitude or even the sign of change substantially depended on the choice of the beginning year. This suggests a non-significant trend in global land ET over the last decade. (letter)

  14. Extended Thermodynamics: a Theory of Symmetric Hyperbolic Field Equations

    Science.gov (United States)

    Müller, Ingo

    2008-12-01

    Extended thermodynamics is based on a set of equations of balance which are supplemented by local and instantaneous constitutive equations so that the field equations are quasi-linear first order differential equations. If the constitutive functions are subject to the requirements of the entropy principle, one may write them in symmetric hyperbolic form by a suitable choice of fields. The kinetic theory of gases, or the moment theories based on the Boltzmann equation provide an explicit example for extended thermodynamics. The theory proves its usefulness and practicality in the successful treatment of light scattering in rarefied gases. This presentation is based upon the book [1] of which the author of this paper is a co-author. For more details about the motivation and exploitation of the basic principles the interested reader is referred to that reference. It would seem that extended thermodynamics is worthy of the attention of mathematicians. It may offer them a non-trivial field of study concerning hyperbolic equations, if ever they get tired of the Burgers equation. Physicists may prefer to appreciate the success of extended thermodynamics in light scattering and to work on the open problems concerning the modification of the Navier-Stokes-Fourier theory in rarefied gases as predicted by extended thermodynamics of 13, 14, and more moments.

  15. A transformed rational function method and exact solutions to the 3+1 dimensional Jimbo-Miwa equation

    International Nuclear Information System (INIS)

    Ma Wenxiu; Lee, J.-H.

    2009-01-01

    A direct approach to exact solutions of nonlinear partial differential equations is proposed, by using rational function transformations. The new method provides a more systematical and convenient handling of the solution process of nonlinear equations, unifying the tanh-function type methods, the homogeneous balance method, the exp-function method, the mapping method, and the F-expansion type methods. Its key point is to search for rational solutions to variable-coefficient ordinary differential equations transformed from given partial differential equations. As an application, the construction problem of exact solutions to the 3+1 dimensional Jimbo-Miwa equation is treated, together with a Baecklund transformation.

  16. 16 reference population equations using peak expiratory flow meters

    African Journals Online (AJOL)

    DR. AMINU

    Many formulae for predicting lung function values for Nigerians have been produced by a lot of investigators. The same principle ... equations in current use are based on linear statistical models which are subject to change and they did not express the .... that present lower limits of normal or present information from which ...

  17. Chemical Equilibrium as Balance of the Thermodynamic Forces

    OpenAIRE

    Zilbergleyt, B.

    2004-01-01

    The article sets forth comprehensive basics of thermodynamics of chemical equilibrium as balance of the thermodynamic forces. Based on the linear equations of irreversible thermodynamics, De Donder definition of the thermodynamic force, and Le Chatelier's principle, new thermodynamics of chemical equilibrium offers an explicit account for multiple chemical interactions within the system. Basic relations between energetic characteristics of chemical transformations and reaction extents are bas...

  18. Stochastic differential equation model to Prendiville processes

    International Nuclear Information System (INIS)

    Granita; Bahar, Arifah

    2015-01-01

    The Prendiville process is another variation of the logistic model which assumes linearly decreasing population growth rate. It is a continuous time Markov chain (CTMC) taking integer values in the finite interval. The continuous time Markov chain can be approximated by stochastic differential equation (SDE). This paper discusses the stochastic differential equation of Prendiville process. The work started with the forward Kolmogorov equation in continuous time Markov chain of Prendiville process. Then it was formulated in the form of a central-difference approximation. The approximation was then used in Fokker-Planck equation in relation to the stochastic differential equation of the Prendiville process. The explicit solution of the Prendiville process was obtained from the stochastic differential equation. Therefore, the mean and variance function of the Prendiville process could be easily found from the explicit solution

  19. Stochastic differential equation model to Prendiville processes

    Energy Technology Data Exchange (ETDEWEB)

    Granita, E-mail: granitafc@gmail.com [Dept. of Mathematical Science, Universiti Teknologi Malaysia, 81310, Johor Malaysia (Malaysia); Bahar, Arifah [Dept. of Mathematical Science, Universiti Teknologi Malaysia, 81310, Johor Malaysia (Malaysia); UTM Center for Industrial & Applied Mathematics (UTM-CIAM) (Malaysia)

    2015-10-22

    The Prendiville process is another variation of the logistic model which assumes linearly decreasing population growth rate. It is a continuous time Markov chain (CTMC) taking integer values in the finite interval. The continuous time Markov chain can be approximated by stochastic differential equation (SDE). This paper discusses the stochastic differential equation of Prendiville process. The work started with the forward Kolmogorov equation in continuous time Markov chain of Prendiville process. Then it was formulated in the form of a central-difference approximation. The approximation was then used in Fokker-Planck equation in relation to the stochastic differential equation of the Prendiville process. The explicit solution of the Prendiville process was obtained from the stochastic differential equation. Therefore, the mean and variance function of the Prendiville process could be easily found from the explicit solution.

  20. Population genomic scan for candidate signatures of balancing selection to guide antigen characterization in malaria parasites.

    Science.gov (United States)

    Amambua-Ngwa, Alfred; Tetteh, Kevin K A; Manske, Magnus; Gomez-Escobar, Natalia; Stewart, Lindsay B; Deerhake, M Elizabeth; Cheeseman, Ian H; Newbold, Christopher I; Holder, Anthony A; Knuepfer, Ellen; Janha, Omar; Jallow, Muminatou; Campino, Susana; Macinnis, Bronwyn; Kwiatkowski, Dominic P; Conway, David J

    2012-01-01

    Acquired immunity in vertebrates maintains polymorphisms in endemic pathogens, leading to identifiable signatures of balancing selection. To comprehensively survey for genes under such selection in the human malaria parasite Plasmodium falciparum, we generated paired-end short-read sequences of parasites in clinical isolates from an endemic Gambian population, which were mapped to the 3D7 strain reference genome to yield high-quality genome-wide coding sequence data for 65 isolates. A minority of genes did not map reliably, including the hypervariable var, rifin, and stevor families, but 5,056 genes (90.9% of all in the genome) had >70% sequence coverage with minimum read depth of 5 for at least 50 isolates, of which 2,853 genes contained 3 or more single nucleotide polymorphisms (SNPs) for analysis of polymorphic site frequency spectra. Against an overall background of negatively skewed frequencies, as expected from historical population expansion combined with purifying selection, the outlying minority of genes with signatures indicating exceptionally intermediate frequencies were identified. Comparing genes with different stage-specificity, such signatures were most common in those with peak expression at the merozoite stage that invades erythrocytes. Members of clag, PfMC-2TM, surfin, and msp3-like gene families were highly represented, the strongest signature being in the msp3-like gene PF10_0355. Analysis of msp3-like transcripts in 45 clinical and 11 laboratory adapted isolates grown to merozoite-containing schizont stages revealed surprisingly low expression of PF10_0355. In diverse clonal parasite lines the protein product was expressed in a minority of mature schizonts (<1% in most lines and ∼10% in clone HB3), and eight sub-clones of HB3 cultured separately had an intermediate spectrum of positive frequencies (0.9 to 7.5%), indicating phase variable expression of this polymorphic antigen. This and other identified targets of balancing selection are now

  1. Population genomic scan for candidate signatures of balancing selection to guide antigen characterization in malaria parasites.

    Directory of Open Access Journals (Sweden)

    Alfred Amambua-Ngwa

    Full Text Available Acquired immunity in vertebrates maintains polymorphisms in endemic pathogens, leading to identifiable signatures of balancing selection. To comprehensively survey for genes under such selection in the human malaria parasite Plasmodium falciparum, we generated paired-end short-read sequences of parasites in clinical isolates from an endemic Gambian population, which were mapped to the 3D7 strain reference genome to yield high-quality genome-wide coding sequence data for 65 isolates. A minority of genes did not map reliably, including the hypervariable var, rifin, and stevor families, but 5,056 genes (90.9% of all in the genome had >70% sequence coverage with minimum read depth of 5 for at least 50 isolates, of which 2,853 genes contained 3 or more single nucleotide polymorphisms (SNPs for analysis of polymorphic site frequency spectra. Against an overall background of negatively skewed frequencies, as expected from historical population expansion combined with purifying selection, the outlying minority of genes with signatures indicating exceptionally intermediate frequencies were identified. Comparing genes with different stage-specificity, such signatures were most common in those with peak expression at the merozoite stage that invades erythrocytes. Members of clag, PfMC-2TM, surfin, and msp3-like gene families were highly represented, the strongest signature being in the msp3-like gene PF10_0355. Analysis of msp3-like transcripts in 45 clinical and 11 laboratory adapted isolates grown to merozoite-containing schizont stages revealed surprisingly low expression of PF10_0355. In diverse clonal parasite lines the protein product was expressed in a minority of mature schizonts (<1% in most lines and ∼10% in clone HB3, and eight sub-clones of HB3 cultured separately had an intermediate spectrum of positive frequencies (0.9 to 7.5%, indicating phase variable expression of this polymorphic antigen. This and other identified targets of balancing

  2. Population decay time and distribution of exciton states analyzed by rate equations based on theoretical phononic and electron-collisional rate coefficients

    Science.gov (United States)

    Oki, Kensuke; Ma, Bei; Ishitani, Yoshihiro

    2017-11-01

    Population distributions and transition fluxes of the A exciton in bulk GaN are theoretically analyzed using rate equations of states of the principal quantum number n up to 5 and the continuum. These rate equations consist of the terms of radiative, electron-collisional, and phononic processes. The dependence of the rate coefficients on temperature is revealed on the basis of the collisional-radiative model of hydrogen plasma for the electron-collisional processes and theoretical formulation using Fermi's "golden rule" for the phononic processes. The respective effects of the variations in electron, exciton, and lattice temperatures are exhibited. This analysis is a base of the discussion on nonthermal equilibrium states of carrier-exciton-phonon dynamics. It is found that the exciton dissociation is enhanced even below 150 K mainly by the increase in the lattice temperature. When the thermal-equilibrium temperature increases, the population fluxes between the states of n >1 and the continuum become more dominant. Below 20 K, the severe deviation from the Saha-Boltzmann distribution occurs owing to the interband excitation flux being higher than the excitation flux from the 1 S state. The population decay time of the 1 S state at 300 K is more than ten times longer than the recombination lifetime of excitons with kinetic energy but without the upper levels (n >1 and the continuum). This phenomenon is caused by a shift of population distribution to the upper levels. This phonon-exciton-radiation model gives insights into the limitations of conventional analyses such as the ABC model, the Arrhenius plot, the two-level model (n =1 and the continuum), and the neglect of the upper levels.

  3. Linear constraint relations in biochemical reaction systems: I. Classification of the calculability and the balanceability of conversion rates.

    Science.gov (United States)

    van der Heijden, R T; Heijnen, J J; Hellinga, C; Romein, B; Luyben, K C

    1994-01-05

    Measurements provide the basis for process monitoring and control as well as for model development and validation. Systematic approaches to increase the accuracy and credibility of the empirical data set are therefore of great value. In (bio)chemical conversions, linear conservation relations such as the balance equations for charge, enthalpy, and/or chemical elements, can be employed to relate conversion rates. In a pactical situation, some of these rates will be measured (in effect, be calculated directly from primary measurements of, e.g., concentrations and flow rates), as others can or cannot be calculated from the measured ones. When certain measured rates can also be calculated from other measured rates, the set of equations, the accuracy and credibility of the measured rates can indeed be improved by, respectively, balancing and gross error diagnosis. The balanced conversion rates are more accurate, and form a consistent set of data, which is more suitable for further application (e.g., to calculate nonmeasured rates) than the raw measurements. Such an approach has drawn attention in previous studies. The current study deals mainly with the problem of mathematically classifying the conversion rates into balanceable and calculable rates, given the subset of measured rates. The significance of this problem is illustrated with some examples. It is shown that a simple matrix equation can be derived that contains the vector of measured conversion rates and the redundancy matrix R. Matrix R plays a predominant role in the classification problem. In supplementary articles, significance of the redundancy matrix R for an improved gross error diagnosis approach will be shown. In addition, efficient equations have been derived to calculate the balanceable and/or calculable rates. The method is completely based on matrix algebra (principally different from the graph-theoretical approach), and it is easily implemented into a computer program. (c) 1994 John Wiley & Sons

  4. Use of Nintendo Wii Balance Board for posturographic analysis of Multiple Sclerosis patients with minimal balance impairment.

    Science.gov (United States)

    Severini, Giacomo; Straudi, Sofia; Pavarelli, Claudia; Da Roit, Marco; Martinuzzi, Carlotta; Di Marco Pizzongolo, Laura; Basaglia, Nino

    2017-03-11

    The Wii Balance Board (WBB) has been proposed as an inexpensive alternative to laboratory-grade Force Plates (FP) for the instrumented assessment of balance. Previous studies have reported a good validity and reliability of the WBB for estimating the path length of the Center of Pressure. Here we extend this analysis to 18 balance related features extracted from healthy subjects (HS) and individuals affected by Multiple Sclerosis (MS) with minimal balance impairment. Eighteen MS patients with minimal balance impairment (Berg Balance Scale 53.3 ± 3.1) and 18 age-matched HS were recruited in this study. All subjects underwent instrumented balance tests on the FP and WBB consisting of quiet standing with the eyes open and closed. Linear correlation analysis and Bland-Altman plots were used to assess relations between path lengths estimated using the WBB and the FP. 18 features were extracted from the instrumented balance tests. Statistical analysis was used to assess significant differences between the features estimated using the WBB and the FP and between HS and MS. The Spearman correlation coefficient was used to evaluate the validity and the Intraclass Correlation Coefficient was used to assess the reliability of WBB measures with respect to the FP. Classifiers based on Support Vector Machines trained on the FP and WBB features were used to assess the ability of both devices to discriminate between HS and MS. We found a significant linear relation between the path lengths calculated from the WBB and the FP indicating an overestimation of these parameters in the WBB. We observed significant differences in the path lengths between FP and WBB in most conditions. However, significant differences were not found for the majority of the other features. We observed the same significant differences between the HS and MS populations across the two measurement systems. Validity and reliability were moderate-to-high for all the analyzed features. Both the FP and WBB

  5. Theory and computation of general force balance in non-axisymmetric tokamak equilibria

    Science.gov (United States)

    Park, Jong-Kyu; Logan, Nikolas; Wang, Zhirui; Kim, Kimin; Boozer, Allen; Liu, Yueqiang; Menard, Jonathan

    2014-10-01

    Non-axisymmetric equilibria in tokamaks can be effectively described by linearized force balance. In addition to the conventional isotropic pressure force, there are three important components that can strongly contribute to the force balance; rotational, anisotropic tensor pressure, and externally given forces, i.e. ∇ --> p + ρv-> . ∇ --> v-> + ∇ --> . Π + f-> = j-> × B-> , especially in, but not limited to, high β and rotating plasmas. Within the assumption of nested flux surfaces, Maxwell equations and energy minimization lead to the modified-generalized Newcomb equation for radial displacements with simple algebraic relations for perpendicular and parallel displacements, including an inhomogeneous term if any of the forces are not explicitly dependent on displacements. The general perturbed equilibrium code (GPEC) solves this force balance consistent with energy and torque given by external perturbations. Local and global behaviors of solutions will be discussed when ∇ --> . Π is solved by the semi-analytic code PENT and will be compared with MARS-K. Any first-principle transport code calculating ∇ --> . Π or f-> , e.g. POCA, can also be incorporated without demanding iterations. This work was supported by DOE Contract DE-AC02-09CH11466.

  6. The Association of Flexibility, Balance, and Lumbar Strength with Balance Ability: Risk of Falls in Older Adults

    Directory of Open Access Journals (Sweden)

    Emilio J. Martínez-López Emilio

    2014-06-01

    Full Text Available The purpose of the present study was to determine the effects of a proprioceptive training program on older adults, as well as to analyze the association between flexibility, balance and lumbar strength (physical fitness test with balance ability and fall risk (functional balance tests. This study was a controlled, longitudinal trial with a 12-week follow-up period. Subjects from a population of older adults were allocated to the intervention group (n = 28 or to the usual care (control group (n = 26. Subjects performed proprioceptive training twice weekly (6 specific exercises with Swiss ball and BOSU. Each session included 50 minutes (10 minutes of warm-up with slow walk, 10 minutes of mobility and stretching exercises, 30 minutes of proprioceptive exercises. The outcome variables were physical fitness (lower-body flexibility, hip-joint mobility, dynamic balance, static balance, and lumbar strength and functional balance (Berg scale and Tinetti test. The experimental group obtained significantly higher values than the control group in lower-body flexibility, dynamic balance, and lumbar strength (p = 0.019, p < 0.001, and p = 0.034 respectively. Hip-joint mobility, dynamic balance, and lumbar strength were positively associated with balance ability (p < 0.001, p < 0.001, and p = 0.014, respectively and the prevention of falls (p = 0.001, p < 0.001, and p = 0.017 respectively. These findings suggest that a 12-week proprioception program intervention (twice a week significantly improves flexibility, balance, and lumbar strength in older adults. Hip-joint mobility, dynamic balance and lumbar strength are positively associated to balance ability and the risk of falls in older adults. This proprioceptive training does not show a significant improvement in hip-joint mobility or static balance.

  7. Balancing Energy Processes in Turbine Engines

    Directory of Open Access Journals (Sweden)

    Balicki Włodzimierz

    2015-01-01

    Full Text Available The article discusses the issue of balancing energy processes in turbine engines in operation in aeronautic and marine propulsion systems with the aim to analyse and evaluate basic operating parameters. The first part presents the problem of enormous amounts of energy needed for driving fans and compressors of the largest contemporary turbofan engines commonly used in long-distance aviation. The amounts of the transmitted power and the effect of flow parameters and constructional properties of the engines on their performance and real efficiency are evaluated. The second part of the article, devoted to marine applications of turbine engines, presents the energy balance of the kinetic system of torque transmission from main engine turbines to screw propellers in the combined system of COGAG type. The physical model of energy conversion processes executed in this system is presented, along with the physical model of gasodynamic processes taking place in a separate driving turbine of a reversing engine. These models have made the basis for formulating balance equations, which then were used for analysing static and dynamic properties of the analysed type of propulsion, in particular in the aspect of mechanical loss evaluation in its kinematic system.

  8. An iterative algorithm for solving the multidimensional neutron diffusion nodal method equations on parallel computers

    International Nuclear Information System (INIS)

    Kirk, B.L.; Azmy, Y.Y.

    1992-01-01

    In this paper the one-group, steady-state neutron diffusion equation in two-dimensional Cartesian geometry is solved using the nodal integral method. The discrete variable equations comprise loosely coupled sets of equations representing the nodal balance of neutrons, as well as neutron current continuity along rows or columns of computational cells. An iterative algorithm that is more suitable for solving large problems concurrently is derived based on the decomposition of the spatial domain and is accelerated using successive overrelaxation. This algorithm is very well suited for parallel computers, especially since the spatial domain decomposition occurs naturally, so that the number of iterations required for convergence does not depend on the number of processors participating in the calculation. Implementation of the authors' algorithm on the Intel iPSC/2 hypercube and Sequent Balance 8000 parallel computer is presented, and measured speedup and efficiency for test problems are reported. The results suggest that the efficiency of the hypercube quickly deteriorates when many processors are used, while the Sequent Balance retains very high efficiency for a comparable number of participating processors. This leads to the conjecture that message-passing parallel computers are not as well suited for this algorithm as shared-memory machines

  9. Power balancing of multibeam laser fusion lasers

    International Nuclear Information System (INIS)

    Seka, W.; Morse, S.; Letzring, S.; Kremens, R.; Kessler, T.J.; Jaanimagi, P.; Keck, R.; Verdon, C.; Brown, D.

    1989-01-01

    The success of laser fusion depends to a good degree on the ability to compress the target to very high densities of ≥1000 times liquid DT. To achieve such compressions require that the irradiation nonuniformity must not exceed ∼1% rms over the whole time of the compression, particularly during the early phases of irradiation. The stringent requirements for the irradiation uniformity for laser fusion have been known for quite some time but until recently the energy balance was mistakenly equated to power balance. The authors describe their effort on energy balance and irradiation patterns on the target. They significantly improved the laser performance with respect to overall intensity distributions on target including the implementation of distributed (random) phase plates in each high power beam. However, the slightly varying performance of the third harmonic conversion crystals in the twenty-four beams of their laser system was generally compensated for by appropriately adjusted 1.054μm input laser energy. Computational analysis of the results of the recent high density campaign are shown

  10. bathymetric survey and estimation of the water balance of lake

    African Journals Online (AJOL)

    Preferred Customer

    The average annual open water evaporation, estimated from Colorado Class-A Pan records and Penman modified method is 23.49 million cubic .... Therefore, the ∆S term in equation 2 can be replaced by the net unmeasured ground .... appears that the steady-state water balance is reasonable. Because, the residual value ...

  11. The Energy Balance of Plasma in a Coaxial Plasma Opening Switch

    International Nuclear Information System (INIS)

    Xu Xiang; Wang Younian

    2006-01-01

    The two-dimensional energy balance in a coaxial plasma opening switch (POS) is studied based on the single-fluid magnetohydrodynamic (MHD) equations coupled with the generalized Ohm's law. The energy transfers between the plasma and the magnetic field are considered during the penetration of the magnetic field as the Ohmic heating is included in the energy-balance equation. The focus is on the energy partition between the magnetic-field energy and the dissipated magnetic-field energy in a high-density POS with different rise-in-time electric currents at the generator boundary. The simulation code is tested in two cases: the constant-in-time current case and the linear rise-in-time current case. For the sinusoidally rise-in-time current similar to that of the experiments, it is shown that at the end of the conduction phase the dissipated magnetic-field energy is 36.5% of the input electromagnetic energy, which is consistent with the experimental results

  12. Metabolite-balancing techniques vs. 13C tracer experiments to determine metabolic fluxes in hybridoma cells.

    Science.gov (United States)

    Bonarius, H P; Timmerarends, B; de Gooijer, C D; Tramper, J

    The estimation of intracellular fluxes of mammalian cells using only mass balances of the relevant metabolites is not possible because the set of linear equations defined by these mass balances is underdetermined. In order to quantify fluxes in cyclic pathways the mass balance equations can be complemented with several constraints: (1) the mass balances of co-metabolites, such as ATP or NAD(P)H, (2) linear objective functions, (3) flux data obtained by isotopic-tracer experiments. Here, these three methods are compared for the analysis of fluxes in the primary metabolism of continuously cultured hybridoma cells. The significance of different theoretical constraints and different objective functions is discussed after comparing their resulting flux distributions to the fluxes determined using 13CO2 and 13C-lactate measurements of 1 - 13C-glucose-fed hybridoma cells. Metabolic fluxes estimated using the objective functions "maximize ATP" and "maximize NADH" are relatively similar to the experimentally determined fluxes. This is consistent with the observation that cancer cells, such as hybridomas, are metabolically hyperactive, and produce ATP and NADH regardless of the need for these cofactors. Copyright 1998 John Wiley & Sons, Inc.

  13. Ultrafast dynamics of laser-pulse excited semiconductors: non-Markovian quantum kinetic equations with nonequilibrium correlations

    Directory of Open Access Journals (Sweden)

    V.V.Ignatyuk

    2004-01-01

    Full Text Available Non-Markovian kinetic equations in the second Born approximation are derived for a two-zone semiconductor excited by a short laser pulse. Both collision dynamics and running nonequilibrium correlations are taken into consideration. The energy balance and relaxation of the system to equilibrium are discussed. Results of numerical solution of the kinetic equations for carriers and phonons are presented.

  14. A balance principle approach for modeling phase transformation kinetics

    International Nuclear Information System (INIS)

    Lusk, M.; Krauss, G.; Jou, H.J.

    1995-01-01

    A balance principle is offered to model volume fraction kinetics of phase transformation kinetics at a continuum level. This microbalance provides a differential equation for transformation kinetics which is coupled to the differential equations governing the mechanical and thermal aspects of the process. Application here is restricted to diffusive transformations for the sake of clarity, although the principle is discussed for martensitic phase transitions as well. Avrami-type kinetics are shown to result from a special class of energy functions. An illustrative example using a 0.5% C Chromium steel demonstrates how TTT and CCT curves can be generated using a particularly simple effective energy function. (orig.)

  15. Existing creatinine-based equations overestimate glomerular filtration rate in Indians.

    Science.gov (United States)

    Kumar, Vivek; Yadav, Ashok Kumar; Yasuda, Yoshinari; Horio, Masaru; Kumar, Vinod; Sahni, Nancy; Gupta, Krishan L; Matsuo, Seiichi; Kohli, Harbir Singh; Jha, Vivekanand

    2018-02-01

    Accurate estimation of glomerular filtration rate (GFR) is important for diagnosis and risk stratification in chronic kidney disease and for selection of living donors. Ethnic differences have required correction factors in the originally developed creatinine-based GFR estimation equations for populations around the world. Existing equations have not been validated in the vegetarian Indian population. We examined the performance of creatinine and cystatin-based GFR estimating equations in Indians. GFR was measured by urinary clearance of inulin. Serum creatinine was measured using IDMS-traceable Jaffe's and enzymatic assays, and cystatin C by colloidal gold immunoassay. Dietary protein intake was calculated by measuring urinary nitrogen appearance. Bias, precision and accuracy were calculated for the eGFR equations. A total of 130 participants (63 healthy kidney donors and 67 with CKD) were studied. About 50% were vegetarians, and the remainder ate meat 3.8 times every month. The average creatinine excretion were 14.7 mg/kg/day (95% CI: 13.5 to 15.9 mg/kg/day) and 12.4 mg/kg/day (95% CI: 11.2 to 13.6 mg/kg/day) in males and females, respectively. The average daily protein intake was 46.1 g/day (95% CI: 43.2 to 48.8 g/day). The mean mGFR in the study population was 51.66 ± 31.68 ml/min/1.73m 2 . All creatinine-based eGFR equations overestimated GFR (p < 0.01 for each creatinine based eGFR equation). However, eGFR by CKD-EPI Cys was not significantly different from mGFR (p = 0.38). The CKD-EPI Cys exhibited lowest bias [mean bias: -3.53 ± 14.70 ml/min/1.73m 2 (95% CI: -0.608 to -0.98)] and highest accuracy (P 30 : 74.6%). The GFR in the healthy population was 79.44 ± 20.19 (range: 41.90-134.50) ml/min/1.73m 2 . Existing creatinine-based GFR estimating equations overestimate GFR in Indians. An appropriately powered study is needed to develop either a correction factor or a new equation for accurate assessment of kidney function in the

  16. Periodic Solutions of the Duffing Harmonic Oscillator by He's Energy Balance Method

    Directory of Open Access Journals (Sweden)

    A. M. El-Naggar

    2015-11-01

    Full Text Available Duffing harmonic oscillator is a common model for nonlinear phenomena in science and engineering. This paper presents He´s Energy Balance Method (EBM for solving nonlinear differential equations. Two strong nonlinear cases have been studied analytically. Analytical results of the EBM are compared with the solutions obtained by using He´s Frequency Amplitude Formulation (FAF and numerical solutions using Runge-Kutta method. The results show the presented method is potentially to solve high nonlinear oscillator equations.

  17. A Derivation of Source-based Kinetics Equation with Time Dependent Fission Kernel for Reactor Transient Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Song Hyun; Woo, Myeong Hyun; Shin, Chang Ho [Hanyang University, Seoul (Korea, Republic of); Pyeon, Cheol Ho [Kyoto University, Osaka (Japan)

    2015-10-15

    In this study, a new balance equation to overcome the problems generated by the previous methods is proposed using source-based balance equation. And then, a simple problem is analyzed with the proposed method. In this study, a source-based balance equation with the time dependent fission kernel was derived to simplify the kinetics equation. To analyze the partial variations of reactor characteristics, two representative methods were introduced in previous studies; (1) quasi-statics method and (2) multipoint technique. The main idea of quasistatics method is to use a low-order approximation for large integration times. To realize the quasi-statics method, first, time dependent flux is separated into the shape and amplitude functions, and shape function is calculated. It is noted that the method has a good accuracy; however, it can be expensive as a calculation cost aspect because the shape function should be fully recalculated to obtain accurate results. To improve the calculation efficiency, multipoint method was proposed. The multipoint method is based on the classic kinetics equation with using Green's function to analyze the flight probability from region r' to r. Those previous methods have been used to analyze the reactor kinetics analysis; however, the previous methods can have some limitations. First, three group variables (r{sub g}, E{sub g}, t{sub g}) should be considered to solve the time dependent balance equation. This leads a big limitation to apply large system problem with good accuracy. Second, the energy group neutrons should be used to analyze reactor kinetics problems. In time dependent problem, neutron energy distribution can be changed at different time. It can affect the change of the group cross section; therefore, it can lead the accuracy problem. Third, the neutrons in a space-time region continually affect the other space-time regions; however, it is not properly considered in the previous method. Using birth history of the

  18. Effects of balance training using a virtual-reality system in older fallers

    Science.gov (United States)

    Duque, Gustavo; Boersma, Derek; Loza-Diaz, Griselda; Hassan, Sanobar; Suarez, Hamlet; Geisinger, Dario; Suriyaarachchi, Pushpa; Sharma, Anita; Demontiero, Oddom

    2013-01-01

    Poor balance is considered a challenging risk factor for falls in older adults. Therefore, innovative interventions for balance improvement in this population are greatly needed. The aim of this study was to evaluate the effect of a new virtual-reality system (the Balance Rehabilitation Unit [BRU]) on balance, falls, and fear of falling in a population of community-dwelling older subjects with a known history of falls. In this study, 60 community-dwelling older subjects were recruited after being diagnosed with poor balance at the Falls and Fractures Clinic, Nepean Hospital (Penrith, NSW, Australia). Subjects were randomly assigned to either the BRU-training or control groups. Both groups received the usual falls prevention care. The BRU-training group attended balance training (two sessions/week for 6 weeks) using an established protocol. Change in balance parameters was assessed in the BRU-training group at the end of their 6-week training program. Both groups were assessed 9 months after their initial assessment (month 0). Adherence to the BRU-training program was 97%. Balance parameters were significantly improved in the BRU-training group (P falls and lower levels of fear of falling (P balance that were improved by BRU training showed a decline after 9 months post-training. In conclusion, BRU training is an effective and well-accepted intervention to improve balance, increase confidence, and prevent falls in the elderly. PMID:23467506

  19. Spousal Support and Work--Family Balance in Launching a Family Business

    Science.gov (United States)

    Gudmunson, Clinton G.; Danes, Sharon M.; Werbel, James D.; Loy, Johnben Teik-Cheok

    2009-01-01

    This study examines whether emotional spousal support contributes to business owners' perceived work-family balance while launching a family business. Hobfoll's Conservation of Resources theory of stress is applied to 109 family business owners and their spouses. Results from structural equation models support several hypotheses. First, reports of…

  20. Comparison of the MDRD Study and CKD-EPI Equations for the Estimation of the Glomerular Filtration Rate in the Korean General Population: The Fifth Korea National Health and Nutrition Examination Survey (KNHANES V-1, 2010

    Directory of Open Access Journals (Sweden)

    Tae-Dong Jeong

    2013-10-01

    Full Text Available Background: We compared the accuracy of the Modification of Diet in Renal Disease (MDRD study and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI equations in Korean patients and evaluated the difference in CKD prevalence determined using the two equations in the Korean general population. Methods: The accuracy of the two equations was evaluated in 607 patients who underwent a chromium-51-ethylenediaminetetraacetic acid GFR measurement. Additionally, we compared the difference in CKD prevalence determined by the two equations among 5,822 participants in the fifth Korea National Health and Nutrition Examination Survey, 2010. Results: Among the 607 subjects, the median bias of the CKD-EPI equation was significantly lower than that of the MDRD study equation (0.9 vs. 2.2, p=0.020. The accuracy of the two equations was not significantly different in patients with mGFR 2; however, the accuracy of the CKD-EPI equation was significantly higher than that of the MDRD study equation in patients with GFR ≥60 mL/min/1.73m2. The prevalences of the CKD stages 1, 2 and 3 in the Korean general population were 47.56, 49.23, and 3.07%, respectively, for the MDRD study equation; and were 68.48, 28.89, and 2.49%, respectively, for the CKD-EPI equation. Conclusions: These data suggest that the CKD-EPI equation might be more useful in clinical practice than the MDRD study equation in Koreans.

  1. Balance ability measured with the Berg balance scale: a determinant of fall history in community-dwelling adults with leg amputation.

    Science.gov (United States)

    Wong, Christopher Kevin; Chen, Christine C; Blackwell, Wren M; Rahal, Rana T; Benoy, Stephany A

    2015-01-01

    Falls are common among adults with leg amputations and associated with balance confidence. But subjective confidence is not equivalent with physical ability. This multivariate analyses of community-dwelling adults with leg amputations examined relationships among individual characteristics, falls, balance ability and balance confidence. Cross-sectional study. Community-dwelling adults with leg amputations recruited from a support group and prosthetic clinic. Subjects provided self-reported medical/fall history, prosthetic functional use, and Activities-specific Balance Confidence (ABC) questionnaire data. Balance ability was assessed with the Berg Balance Scale (BBS). Fall incidence was categorized as any fall (one or more) and recurrent falls (more than one). Multivariate logistic regression analyzed relationships within the two fall categories. Cross tabulations and ANOVA analyzed differences among subcategories. Fifty-four subjects (mean age 56.8) with various etiologies, amputation levels, and balance abilities participated. 53.7% had any fall; 25.9% had recurrent falls. Models for both fall categories correctly classified fall history in > 70% of subjects with combinations of the variables ABC, BBS, body-mass-index, and amputation level. Falls occurred regardless of clinical characteristics. Total BBS and select item scores were independent determinants of fall history. Unlike other balance-impaired populations, adults with leg amputation and better balance ability had greater odds of falling.

  2. On derivation and interpretation of Kuo-Eliassen equation

    Directory of Open Access Journals (Sweden)

    Jun-Ichi Yano

    2011-05-01

    Full Text Available The Kuo–Eliassen equation provides a balance condition for both tropical–cyclone like vortex systems as well as zonally–symmetric meridional circulations. This condition is examined with the former application more in mind. The condition is derived more ped- agogically based on the bounded derivative method. Some physical interpretations as well as basic mathematical remarks on this condition are provided. Analogy with quasi–geostrophic system is also remarked.

  3. Game Utilization as a Media to Train the Balance of Left and Right Brain

    Directory of Open Access Journals (Sweden)

    Evan Wijaya

    2017-10-01

    Full Text Available Human have two brain hemispheres, left hemisphere and right hemisphere. Left hemisphere is used for processing language, words, numbers, equations, etc. Right hemisphere is used for processing creativity, imagination, music, color, etc. Every human should have balance between left and right hemisphere. One method that could be used for balancing brain hemispheres is to use left and right hands for using tools, writing, or typing. “Typing Rhythm” is a game for PC platform, the purpose of this game is for brain balancing exercise by typing lyric of a song while the song is played.

  4. China's Energy Equation: A Strategic Opportunity

    National Research Council Canada - National Science Library

    Burke, James

    2001-01-01

    .... Continued economic growth, which is the key to China's future, is constrained by a skewed energy equation in which domestic and foreign energy supplies are far removed from China's burgeoning population...

  5. Well balanced finite volume methods for nearly hydrostatic flows

    International Nuclear Information System (INIS)

    Botta, N.; Klein, R.; Langenberg, S.; Luetzenkirchen, S.

    2004-01-01

    In numerical approximations of nearly hydrostatic flows, a proper representation of the dominant hydrostatic balance is of crucial importance: unbalanced truncation errors can induce unacceptable spurious motions, e.g., in dynamical cores of models for numerical weather prediction (NWP) in particular near steep topography. In this paper we develop a new strategy for the construction of discretizations that are 'well-balanced' with respect to dominant hydrostatics. The classical idea of formulating the momentum balance in terms of deviations of pressure from a balanced background distribution is realized here through local, time dependent hydrostatic reconstructions. Balanced discretizations of the pressure gradient and of the gravitation source term are achieved through a 'discrete Archimedes' buoyancy principle'. This strategy is applied to extend an explicit standard finite volume Godunov-type scheme for compressible flows with minimal modifications. The resulting method has the following features: (i) It inherits its conservation properties from the underlying base scheme. (ii) It is exactly balanced, even on curvilinear grids, for a large class of near-hydrostatic flows. (iii) It solves the full compressible flow equations without reference to a background state that is defined for an entire vertical column of air. (iv) It is robust with respect to details of the implementation, such as the choice of slope limiting functions, or the particularities of boundary condition discretizations

  6. Kinetic Model of Growth of Arthropoda Populations

    Science.gov (United States)

    Ershov, Yu. A.; Kuznetsov, M. A.

    2018-05-01

    Kinetic equations were derived for calculating the growth of crustacean populations ( Crustacea) based on the biological growth model suggested earlier using shrimp ( Caridea) populations as an example. The development cycle of successive stages for populations can be represented in the form of quasi-chemical equations. The kinetic equations that describe the development cycle of crustaceans allow quantitative prediction of the development of populations depending on conditions. In contrast to extrapolation-simulation models, in the developed kinetic model of biological growth the kinetic parameters are the experimental characteristics of population growth. Verification and parametric identification of the developed model on the basis of the experimental data showed agreement with experiment within the error of the measurement technique.

  7. Harmonic Balance Computations of Fan Aeroelastic Stability

    Science.gov (United States)

    Bakhle, Milind A.; Reddy, T. S. R.

    2010-01-01

    A harmonic balance (HB) aeroelastic analysis, which has been recently developed, was used to determine the aeroelastic stability (flutter) characteristics of an experimental fan. To assess the numerical accuracy of this HB aeroelastic analysis, a time-domain aeroelastic analysis was also used to determine the aeroelastic stability characteristics of the same fan. Both of these three-dimensional analysis codes model the unsteady flowfield due to blade vibrations using the Reynolds-averaged Navier-Stokes (RANS) equations. In the HB analysis, the unsteady flow equations are converted to a HB form and solved using a pseudo-time marching method. In the time-domain analysis, the unsteady flow equations are solved using an implicit time-marching approach. Steady and unsteady computations for two vibration modes were carried out at two rotational speeds: 100 percent (design) and 70 percent (part-speed). The steady and unsteady results obtained from the two analysis methods compare well, thus verifying the recently developed HB aeroelastic analysis. Based on the results, the experimental fan was found to have no aeroelastic instability (flutter) at the conditions examined in this study.

  8. Nonlocal constitutive equations of elasto-visco-plasticity coupled with damage and temperature

    Directory of Open Access Journals (Sweden)

    Liu Weijie

    2016-01-01

    Full Text Available In this paper, the nonlocal anisothermal elasto-visco-plastic constitutive equations strongly coupled with ductile isotropic damage, nonlinear isotropic hardening and kinematic hardening are developed to model the material behaviour under finite strain. The new micromorphic variable of damage is introduced into the principle of virtual power and new additional balance equations are obtained. Thermodynamically-consistent nonlocal constitutive equations are then deduced. The evolution equations are deduced from the generalized normality rule for the Norton-Hoff visco-plastic potential. This model is used to simulate various material responses under different velocities at high temperature. The micromorphic parameters of damage: micromorphic density and H moduli are studied to examine the effects of micromorphic damage. Biaxial tension is performed to make a comparison between the local damage model and the micromorphic damage model.

  9. Speed ot travelling waves in reaction-diffusion equations

    International Nuclear Information System (INIS)

    Benguria, R.D.; Depassier, M.C.; Mendez, V.

    2002-01-01

    Reaction diffusion equations arise in several problems of population dynamics, flame propagation and others. In one dimensional cases the systems may evolve into travelling fronts. Here we concentrate on a reaction diffusion equation which arises as a simple model for chemotaxis and present results for the speed of the travelling fronts. (Author)

  10. Applied analysis and differential equations

    CERN Document Server

    Cârj, Ovidiu

    2007-01-01

    This volume contains refereed research articles written by experts in the field of applied analysis, differential equations and related topics. Well-known leading mathematicians worldwide and prominent young scientists cover a diverse range of topics, including the most exciting recent developments. A broad range of topics of recent interest are treated: existence, uniqueness, viability, asymptotic stability, viscosity solutions, controllability and numerical analysis for ODE, PDE and stochastic equations. The scope of the book is wide, ranging from pure mathematics to various applied fields such as classical mechanics, biomedicine, and population dynamics.

  11. Non-Equilibrium Turbulence and Two-Equation Modeling

    Science.gov (United States)

    Rubinstein, Robert

    2011-01-01

    Two-equation turbulence models are analyzed from the perspective of spectral closure theories. Kolmogorov theory provides useful information for models, but it is limited to equilibrium conditions in which the energy spectrum has relaxed to a steady state consistent with the forcing at large scales; it does not describe transient evolution between such states. Transient evolution is necessarily through nonequilibrium states, which can only be found from a theory of turbulence evolution, such as one provided by a spectral closure. When the departure from equilibrium is small, perturbation theory can be used to approximate the evolution by a two-equation model. The perturbation theory also gives explicit conditions under which this model can be valid, and when it will fail. Implications of the non-equilibrium corrections for the classic Tennekes-Lumley balance in the dissipation rate equation are drawn: it is possible to establish both the cancellation of the leading order Re1/2 divergent contributions to vortex stretching and enstrophy destruction, and the existence of a nonzero difference which is finite in the limit of infinite Reynolds number.

  12. The impact of population growth on environment: the debate heats up.

    Science.gov (United States)

    Shaw, R P

    1992-02-01

    A proposed framework, which was introduced at the 1989 meetings of the American Association for the Advancement of Science, included political constraints as well as population growth as a proximate cause with potentially important impacts on the environment in Paul and Ann Ehrlich's well-known PAT equation. PAT limitations are identified as the 1.2 billion people caught in the debt-poverty trap, less developed countries' balance of payments deficits, and "distortionary factors" that undermined economic incentives and contributed to mismanagement of resources. Such factors could be keeping farm prices low and have an impact on deterring use of environmentally sound traditional agricultural practices. Mismanagement of public lands occurs when large commercial enterprises or large scale mechanization displace population onto marginal or less productive lands. Intergroup warfare is a new form impacting on the environment. In Burma loggers are authorized to clear cut large tracts of teak forests in order to ferret out Karen guerrillas. Over 15 million refugees were thus displaced and forced to live in encampments that require trees for shelter, firewood for survival, and overgrazing of livestock. Social and economic environments are also undermined by "dependency" factors such as trade protectionism, brain drain, and limited foreign aid. The Group of 77 Non-Aligned Developing Countries proposed that discussions of the links between population and the environment be omitted from the agenda of the 1994 UN Conference on Population and Development. Basic clarifications are needed to distinguish ultimate versus proximate factors and current versus future concerns. The debate ignores distribution patterns, migration, or changing age structures. The debate blames unjustifiably rapid population growth as the ultimate cause of global environmental degradation and links population growth to a host of other social problems such as famine and refugees, while ignoring civil unrest

  13. Equations of motion for two-phase flow in a pin bundle of a nuclear reactor

    International Nuclear Information System (INIS)

    Chawla, T.C.; Ishii, M.

    1978-01-01

    By performing Eulerian area averaging over a channel area of the local continuity, momentum, and energy equations for single phase turbulent flow and assuming each phase in two-phase flows to be continuum but coupled by the appropriate 'jump' conditions at the interface, the corresponding axial macroscopic balances for two-fluid model in a pin bundle are obtained. To determine the crossflow, a momentum equation in transverse (to the gap between the pins) direction is obtained for each phase by carrying out Eulerian segment averaging of the local momentum equation, where the segment is taken parallel to the gap. By considering the mixture as a whole, a diffusion model based on drift-flux velocity is formulated. In the axial direction it is expressed in terms of three mixture conservation equations of mass, momentum, and energy with one additional continuity equation for the vapor phase. For the determination of crossflow, transverse momentum equation for a mixture is obtained. It is considered that the previous formulation of the two-phase flow based on the 'slip' flow model and the integral subchannel balances using finite control volumes is inadequate in that the model is heuristic and, a priori, assumes the order of magnitude of the terms, also the model is incomplete and incorrect when applied to two-phase mixtures in thermal non-equilibrium such as during accidental depressurization of a water cooled reactor. The governing equations presented are shown to be a very formal and sound physical basis and are indispensable for physically correct methods of analyzing two-phase flows in a pin bundle. (author)

  14. Iterative Strain-Gage Balance Calibration Data Analysis for Extended Independent Variable Sets

    Science.gov (United States)

    Ulbrich, Norbert Manfred

    2011-01-01

    A new method was developed that makes it possible to use an extended set of independent calibration variables for an iterative analysis of wind tunnel strain gage balance calibration data. The new method permits the application of the iterative analysis method whenever the total number of balance loads and other independent calibration variables is greater than the total number of measured strain gage outputs. Iteration equations used by the iterative analysis method have the limitation that the number of independent and dependent variables must match. The new method circumvents this limitation. It simply adds a missing dependent variable to the original data set by using an additional independent variable also as an additional dependent variable. Then, the desired solution of the regression analysis problem can be obtained that fits each gage output as a function of both the original and additional independent calibration variables. The final regression coefficients can be converted to data reduction matrix coefficients because the missing dependent variables were added to the data set without changing the regression analysis result for each gage output. Therefore, the new method still supports the application of the two load iteration equation choices that the iterative method traditionally uses for the prediction of balance loads during a wind tunnel test. An example is discussed in the paper that illustrates the application of the new method to a realistic simulation of temperature dependent calibration data set of a six component balance.

  15. Hamiltonian formulation of systems with balanced loss-gain and exactly solvable models

    Science.gov (United States)

    Ghosh, Pijush K.; Sinha, Debdeep

    2018-01-01

    A Hamiltonian formulation of generic many-body systems with balanced loss and gain is presented. It is shown that a Hamiltonian formulation is possible only if the balancing of loss and gain terms occurs in a pairwise fashion. It is also shown that with the choice of a suitable co-ordinate, the Hamiltonian can always be reformulated in the background of a pseudo-Euclidean metric. If the equations of motion of some of the well-known many-body systems like Calogero models are generalized to include balanced loss and gain, it appears that the same may not be amenable to a Hamiltonian formulation. A few exactly solvable systems with balanced loss and gain, along with a set of integrals of motion are constructed. The examples include a coupled chain of nonlinear oscillators and a many-particle Calogero-type model with four-body inverse square plus two-body pair-wise harmonic interactions. For the case of nonlinear oscillators, stable solution exists even if the loss and gain parameter has unbounded upper range. Further, the range of the parameter for which the stable solutions are obtained is independent of the total number of the oscillators. The set of coupled nonlinear equations are solved exactly for the case when the values of all the constants of motions except the Hamiltonian are equal to zero. Exact, analytical classical solutions are presented for all the examples considered.

  16. Examining the nomological network of satisfaction with work-life balance.

    Science.gov (United States)

    Grawitch, Matthew J; Maloney, Patrick W; Barber, Larissa K; Mooshegian, Stephanie E

    2013-07-01

    This study expands on past work-life research by examining the nomological network of satisfaction with work-life balance-the overall appraisal or global assessment of how one manages time and energy across work and nonwork domains. Analyses using 456 employees at a midsized organization indicated expected relationships with bidirectional conflict, bidirectional facilitation, and satisfaction with work and nonwork life. Structural equation modeling supported the utility of satisfaction with balance as a unique component of work-life interface perceptions. Results also indicated that satisfaction with balance mediated the relationship between some conflict/facilitation and life satisfaction outcomes, though conflict and facilitation maintained unique predictive validity on domain specific outcomes (i.e., work-to-life conflict and facilitation with work life satisfaction; life-to-work conflict and facilitation with nonwork life satisfaction). PsycINFO Database Record (c) 2013 APA, all rights reserved.

  17. Study of a Model Equation in Detonation Theory

    KAUST Repository

    Faria, Luiz

    2014-04-24

    Here we analyze properties of an equation that we previously proposed to model the dynamics of unstable detonation waves [A. R. Kasimov, L. M. Faria, and R. R. Rosales, Model for shock wave chaos, Phys. Rev. Lett., 110 (2013), 104104]. The equation is ut+ 1/2 (u2-uu (0-, t))x=f (x, u (0-, t)), x > 0, t < 0. It describes a detonation shock at x = 0 with the reaction zone in x > 0. We investigate the nature of the steady-state solutions of this nonlocal hyperbolic balance law, the linear stability of these solutions, and the nonlinear dynamics. We establish the existence of instability followed by a cascade of period-doubling bifurcations leading to chaos. © 2014 Society for Industrial and Applied Mathematics.

  18. Notes on Well-Posed, Ensemble Averaged Conservation Equations for Multiphase, Multi-Component, and Multi-Material Flows

    International Nuclear Information System (INIS)

    Ray A. Berry

    2005-01-01

    At the INL researchers and engineers routinely encounter multiphase, multi-component, and/or multi-material flows. Some examples include: Reactor coolant flows Molten corium flows Dynamic compaction of metal powders Spray forming and thermal plasma spraying Plasma quench reactor Subsurface flows, particularly in the vadose zone Internal flows within fuel cells Black liquor atomization and combustion Wheat-chaff classification in combine harvesters Generation IV pebble bed, high temperature gas reactor The complexity of these flows dictates that they be examined in an averaged sense. Typically one would begin with known (or at least postulated) microscopic flow relations that hold on the ''small'' scale. These include continuum level conservation of mass, balance of species mass and momentum, conservation of energy, and a statement of the second law of thermodynamics often in the form of an entropy inequality (such as the Clausius-Duhem inequality). The averaged or macroscopic conservation equations and entropy inequalities are then obtained from the microscopic equations through suitable averaging procedures. At this stage a stronger form of the second law may also be postulated for the mixture of phases or materials. To render the evolutionary material flow balance system unique, constitutive equations and phase or material interaction relations are introduced from experimental observation, or by postulation, through strict enforcement of the constraints or restrictions resulting from the averaged entropy inequalities. These averaged equations form the governing equation system for the dynamic evolution of these mixture flows. Most commonly, the averaging technique utilized is either volume or time averaging or a combination of the two. The flow restrictions required for volume and time averaging to be valid can be severe, and violations of these restrictions are often found. A more general, less restrictive (and far less commonly used) type of averaging known as

  19. Effects of collisions on level populations and dielectronic recombination rates of multiply charged ions

    International Nuclear Information System (INIS)

    Jacobs, V.L.; Davis, J.

    1978-01-01

    A generalization of previously reported statistical theories is developed for determining the excited-level populations and the ionization-recombination balance of multiply charged atomic ions in an optically thin high-temperature plasma. Account is taken of the most important collisional and radiative processes involving bound and autoionizing levels in three consecutive ionization stages. We obtain a set of rate equations for the population densities of the low-lying levels which contains effective excitation, ionization, and recombination rates describing indirect transitions through the more highly excited bound and autoionizing levels. The familiar corona-model equations for the ground-state populations are recovered by making the assumption that all excited states decay by only spontaneous radiative or autoionization processes. When collisional processes become efficient in depopulating the highly excited levels important in dielectronic recombination, the effective rate of recombination must be described by a collisional-dielectronic recombination coefficient. Results of calculations are presented for the collisional-dielectronic recombination rate coefficients for recombination of Fe +8 --Fe +13 ions. At an electron density of 10 16 cm -3 , dielectronic recombination is still the dominant recombination process. However, the collisional-dielectronic recombination rate coefficients are found to be reduced by about an order of magnitude from their corona-model values due to the effects of multiple-collisional excitations on the populations of the highly excited bound levels of the recombined ion. The dielectronic recombination rates into these highly excited levels are found to be enhanced by the effects of collisionally induced angular momentum redistribution on the populations of the autoionizing levels

  20. Wii-habilitation as balance therapy for children with acquired brain injury.

    Science.gov (United States)

    Tatla, Sandy K; Radomski, Anna; Cheung, Jessica; Maron, Melissa; Jarus, Tal

    2014-02-01

    To evaluate the effectiveness of the Nintendo Wii compared to traditional balance therapy in improving balance, motivation, and functional ability in children undergoing acute rehabilitation after brain injury. A non-concurrent, randomized multiple baseline single-subject research design was used with three participants. Data were analyzed by visual inspection of trend lines. Daily Wii balance training was equally motivating to traditional balance therapy for two participants and more motivating for one participant. While improvements in dynamic balance were observed, the results for static balance remain inconclusive. All participants demonstrated improvements in functional ability. Wii balance therapy is a safe, feasible, and motivating intervention for children undergoing acute rehabilitation after an acquired brain injury. Further research to examine the effectiveness of Wii balance therapy in this population is warranted.

  1. General existence principles for Stieltjes differential equations with applications to mathematical biology

    Science.gov (United States)

    López Pouso, Rodrigo; Márquez Albés, Ignacio

    2018-04-01

    Stieltjes differential equations, which contain equations with impulses and equations on time scales as particular cases, simply consist on replacing usual derivatives by derivatives with respect to a nondecreasing function. In this paper we prove new existence results for functional and discontinuous Stieltjes differential equations and we show that such general results have real world applications. Specifically, we show that Stieltjes differential equations are specially suitable to study populations which exhibit dormant states and/or very short (impulsive) periods of reproduction. In particular, we construct two mathematical models for the evolution of a silkworm population. Our first model can be explicitly solved, as it consists on a linear Stieltjes equation. Our second model, more realistic, is nonlinear, discontinuous and functional, and we deduce the existence of solutions by means of a result proven in this paper.

  2. Validation of the Ejike-Ijeh equations for the estimation of body fat ...

    African Journals Online (AJOL)

    The Ejike-Ijeh equations for the estimation of body fat percentage makes it possible for the body fat content of individuals and populations to be determined without the use of costly equipment. However, because the equations were derived using data from a young-adult (18-29 years old) Nigerian population, it is important ...

  3. The groundwater balance in alluvial plain aquifer at Dehgolan, Kurdistan, Iran

    Science.gov (United States)

    Amini, Ata; Homayounfar, Vafa

    2017-10-01

    In this research, groundwater balance in Dehgolan plain, Kurdistan, Iran was carried out to assess changes in the level and volume of groundwater and water resources management. For this purpose, water resources supplies and consumption data, amount of charging and discharge and water level data recorded from wells and piezometers from 2010 to 2011 water year were gathered and analyzed. Rainfall and water losses of the study area were determined and required maps, including Iso-maps of the temperature, the evaporation, the groundwater level and the aquifer conductivity, were drawn by GIS software. Using the information and drawn maps and the equality of inputs and outputs data, the aquifer water balance was calculated. The results of balance equations showed that the balance is negative indicated a notably decline of groundwater equal to 15.029 million cubic meter (MCM). Such rate of decline is due to the large number of agricultural wells in the region, without considering the hydrological potential of the aquifer.

  4. Effect of peristalsis in balance of intestinal microbial ecosystem

    Science.gov (United States)

    Mirbagheri, Seyed Amir; Fu, Henry C.

    2017-11-01

    A balance of microbiota density in gastrointestinal tracts is necessary for health of the host. Although peristaltic flow made by intestinal muscles is constantly evacuating the lumen, bacterial density stay balanced. Some of bacteria colonize in the secreted mucus where there is no flow, but the rest resist the peristaltic flow in lumen and maintain their population. Using a coupled two-dimensional model of flow induced by large amplitude peristaltic waves, bacterial motility, reproduction, and diffusion, we address how bacterial growth and motility combined with peristaltic flow affect the balance of the intestinal microbial ecosystem.

  5. Multiscale Analysis of Effects of Additive and Multiplicative Noise on Delay Differential Equations near a Bifurcation Point

    International Nuclear Information System (INIS)

    Klosek, M.M.

    2004-01-01

    We study effects of noisy and deterministic perturbations on oscillatory solutions to delay differential equations. We develop the multiscale technique and derive amplitude equations for noisy oscillations near a critical delay. We investigate effects of additive and multiplicative noise. We show that if the magnitudes of noise and deterministic perturbations are balanced, then the oscillatory behavior persists for long times being sustained by the noise. We illustrate the technique and its results on linear and logistic delay equations. (author)

  6. Regression equations to predict 6-minute walk distance in Chinese adults aged 55–85 years

    OpenAIRE

    Shirley P.C. Ngai, PhD; Alice Y.M. Jones, PhD; Sue C. Jenkins, PhD

    2014-01-01

    The 6-minute walk distance (6MWD) is used as a measure of functional exercise capacity in clinical populations and research. Reference equations to predict 6MWD in different populations have been established, however, available equations for Chinese population are scarce. This study aimed to develop regression equations to predict the 6MWD for a Hong Kong Chinese population. Fifty-three healthy individuals (25 men, 28 women; mean age = 69.3 ± 6.5 years) participated in this cross-sectional st...

  7. Opacity calculations and Saha's equation for high Z elements

    International Nuclear Information System (INIS)

    Godwal, B.K.; Sikka, S.K.

    1977-01-01

    Opacity calculations are needed for energy transport by radiation for high Z element plasmas as these have been suggested as temper materials in laser, electron beam and heavy ion fusion schemes. The pressure ionised modified form of Saha's ionisation equation has been used to obtain the free electron density, populations of various ionic species and the populations of various energy states for a given ion. Results are presented for two typical elements; tungsten and uranium. The ionisation potential have been evaluated using the Bohr's formula with suitable effective screened charges for ions. The results show that for uranium, even at a temperature of 10 kev, the K shell is intact. The reliability of the Saha's equation solution has been checked by comparing the equation of state (total pressure vs total energy curve) with that given by the Thomas-Fermi-Dirac equation of state. The agreement between the two is good from temperature upwards of 0.2 kev. (author)

  8. Non-instantaneous impulses in differential equations

    CERN Document Server

    Agarwal, Ravi; O'Regan, Donal

    2017-01-01

    This monograph is the first published book devoted to the theory of differential equations with non-instantaneous impulses. It aims to equip the reader with mathematical models and theory behind real life processes in physics, biology, population dynamics, ecology and pharmacokinetics. The authors examine a wide scope of differential equations with non-instantaneous impulses through three comprehensive chapters, providing an all-rounded and unique presentation on the topic, including: - Ordinary differential equations with non-instantaneous impulses (scalar and n-dimensional case) - Fractional differential equa tions with non-instantaneous impulses (with Caputo fractional derivatives of order q ϵ (0, 1)) - Ordinary differential equations with non-instantaneous impulses occurring at random moments (with exponential, Erlang, or Gamma distribution) Each chapter focuses on theory, proofs and examples, and contains numerous graphs to enrich the reader’s understanding. Additionally, a carefully selected bibliogr...

  9. The Whole Earth Happens As You Do. The Balance of Lifekind.

    Science.gov (United States)

    Archbald, David; McInnis, Noel

    This booklet presents a unified perspective of natural and human systems. The problems of contemporary civilization are analyzed in terms of the interrelationships among energy, food, evolution, population, community, interactions, and balance. The authors' philosophy emphasizes that all life depends on the balance between natural systems and…

  10. Comparative analysis of solution methods of the punctual kinetic equations

    International Nuclear Information System (INIS)

    Hernandez S, A.

    2003-01-01

    The following one written it presents a comparative analysis among different analytical solutions for the punctual kinetics equation, which present two variables of interest: a) the temporary behavior of the neutronic population, and b) The temporary behavior of the different groups of precursors of delayed neutrons. The first solution is based on a method that solves the transfer function of the differential equation for the neutronic population, in which intends to obtain the different poles that give the stability of this transfer function. In this section it is demonstrated that the temporary variation of the reactivity of the system can be managed as it is required, since the integration time for this method doesn't affect the result. However, the second solution is based on an iterative method like that of Runge-Kutta or the Euler method where the algorithm was only used to solve first order differential equations giving this way solution to each differential equation that conforms the equations of punctual kinetics. In this section it is demonstrated that only it can obtain a correct temporary behavior of the neutronic population when it is integrated on an interval of very short time, forcing to the temporary variation of the reactivity to change very quick way without one has some control about the time. In both methods the same change is used so much in the reactivity of the system like in the integration times, giving validity to the results graph the one the temporary behavior of the neutronic population vs. time. (Author)

  11. Algorithms For Integrating Nonlinear Differential Equations

    Science.gov (United States)

    Freed, A. D.; Walker, K. P.

    1994-01-01

    Improved algorithms developed for use in numerical integration of systems of nonhomogenous, nonlinear, first-order, ordinary differential equations. In comparison with integration algorithms, these algorithms offer greater stability and accuracy. Several asymptotically correct, thereby enabling retention of stability and accuracy when large increments of independent variable used. Accuracies attainable demonstrated by applying them to systems of nonlinear, first-order, differential equations that arise in study of viscoplastic behavior, spread of acquired immune-deficiency syndrome (AIDS) virus and predator/prey populations.

  12. Prediction equations for spirometry in adults from northern India.

    Science.gov (United States)

    Chhabra, S K; Kumar, R; Gupta, U; Rahman, M; Dash, D J

    2014-01-01

    Most of the Indian studies on prediction equations for spirometry in adults are several decades old and may have lost their utility as these were carried out with equipment and standardisation protocols that have since changed. Their validity is further questionable as the lung health of the population is likely to have changed over time. To develop prediction equations for spirometry in adults of north Indian origin using the 2005 American Thoracic Society/European Respiratory Society (ATS/ERS) recommendations on standardisation. Normal healthy non-smoker subjects, both males and females, aged 18 years and above underwent spirometry using a non-heated Fleisch Pneumotach spirometer calibrated daily. The dataset was randomly divided into training (70%) and test (30%) sets and the former was used to develop the equations. These were validated on the test data set. Prediction equations were developed separately for males and females for forced vital capacity (FVC), forced expiratory volume in first second (FEV1), FEV1/FVC ratio, and instantaneous expiratory flow rates using multiple linear regression procedure with different transformations of dependent and/or independent variables to achieve the best-fitting models for the data. The equations were compared with the previous ones developed in the same population in the 1960s. In all, 685 (489 males, 196 females) subjects performed spirometry that was technically acceptable and repeatable. All the spirometry parameters were significantly higher among males except the FEV1/FVC ratio that was significantly higher in females. Overall, age had a negative relationship with the spirometry parameters while height was positively correlated with each, except for the FEV1/FVC ratio that was related only to age. Weight was included in the models for FVC, forced expiratory flow (FEF75) and FEV1/FVC ratio in males, but its contribution was very small. Standard errors of estimate were provided to enable calculation of the lower

  13. Establishing Normative Values for the Barnett Balance Assessment Tool: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Monica L. Cercone MSOTS

    2014-04-01

    Full Text Available The purpose of this study was to establish normative data for the Barnett Balance Assessment (BBA for individuals ages 18-70+ years. The BBA is a newly developed assessment tool that may address limitations present in other assessments currently used to detect balance deficits. The BBA was administered to 141 participants who had no history of medical issues that could impact balance. A review of the normative data collected indicated little variation in total assessment scores in the age categories of 18-29, 30-39, and 40-49, due to the presence of a ceiling effect. Variations existed in scores among participants in the remaining age categories (50-59, 60-69, and 70+. These findings may imply that the BBA has its greatest discriminative power in assessing individuals with impaired balance, and/or that the BBA is not sensitive enough to detect differences in individuals with mild balance impairments. The researchers suggest future studies be conducted with the BBA to establish norms with populations with known orthopedic or neurological conditions that may impair balance. Results of these studies could then be compared with the baseline data gathered in this study to determine the BBA’s usefulness in detecting balance impairments with clinical populations.

  14. A Wii Bit of Fun: A Novel Platform to Deliver Effective Balance Training to Older Adults.

    Science.gov (United States)

    Whyatt, Caroline; Merriman, Niamh A; Young, William R; Newell, Fiona N; Craig, Cathy

    2015-12-01

    Falls and fall-related injuries are symptomatic of an aging population. This study aimed to design, develop, and deliver a novel method of balance training, using an interactive game-based system to promote engagement, with the inclusion of older adults at both high and low risk of experiencing a fall. Eighty-two older adults (65 years of age and older) were recruited from sheltered accommodation and local activity groups. Forty volunteers were randomly selected and received 5 weeks of balance game training (5 males, 35 females; mean, 77.18 ± 6.59 years), whereas the remaining control participants recorded levels of physical activity (20 males, 22 females; mean, 76.62 ± 7.28 years). The effect of balance game training was measured on levels of functional balance and balance confidence in individuals with and without quantifiable balance impairments. Balance game training had a significant effect on levels of functional balance and balance confidence (P Commercial hardware can be modified to deliver engaging methods of effective balance assessment and training for the older population.

  15. Modelling and computing the peaks of carbon emission with balanced growth

    International Nuclear Information System (INIS)

    Chang, Shuhua; Wang, Xinyu; Wang, Zheng

    2016-01-01

    Highlights: • We use a more practical utility function to quantify the society’s welfare. • A so-called discontinuous Galerkin method is proposed to solve the ordinary differential equation satisfied by the consumption. • The theoretical results of the discontinuous Galerkin method are obtained. • We establish a Markov model to forecast the energy mix and the industrial structure. - Abstract: In this paper, we assume that under the balanced and optimal economic growth path, the economic growth rate is equal to the consumption growth rate, from which we can obtain the ordinary differential equation governing the consumption level by solving an optimal control problem. Then, a novel numerical method, namely a so-called discontinuous Galerkin method, is applied to solve the ordinary differential equation. The error estimation and the superconvergence estimation of this method are also performed. The model’s mechanism, which makes our assumption coherent, is that once the energy intensity is given, the economic growth is determined, followed by the GDP, the energy demand and the emissions. By applying this model to China, we obtain the conclusion that under the balanced and optimal economic growth path the CO_2 emission will reach its peak in 2030 in China, which is consistent with the U.S.-China Joint Announcement on Climate Change and with other previous scientific results.

  16. Heider balance, asymmetric ties, and gender segregation

    Science.gov (United States)

    Krawczyk, Małgorzata J.; del Castillo-Mussot, Marcelo; Hernández-Ramírez, Eric; Naumis, Gerardo G.; Kułakowski, Krzysztof

    2015-12-01

    To remove a cognitive dissonance in interpersonal relations, people tend to divide their acquaintances into friendly and hostile parts, both groups internally friendly and mutually hostile. This process is modeled as an evolution toward the Heider balance. A set of differential equations have been proposed and validated (Kułakowski et al., 2005) to model the Heider dynamics of this social and psychological process. Here we generalize the model by including the initial asymmetry of the interpersonal relations and the direct reciprocity effect which removes this asymmetry. Our model is applied to the data on enmity and friendship in 37 school classes and 4 groups of teachers in México. For each class, a stable balanced partition is obtained into two groups. The gender structure of the groups reveals stronger gender segregation in younger classes, i.e. of age below 12 years, a fact consistent with other general empirical results.

  17. Detailed balance of the Feynman micromotor

    Science.gov (United States)

    Abbott, Derek; Davis, Bruce R.; Parrondo, Juan M. R.

    1999-09-01

    One existing implication of micromotors is that they can be powered by rectifying non-equilibrium thermal fluctuations or mechanical vibrations via the so-called Feynman- micromotor. An example of mechanical rectification is found in the batteryless wristwatch. The original concept was described in as early as 1912 by Smoluchowski and was later revisited in 1963 by Feynman, in the context of rectifying thermal fluctuations to obtain useful motion. It has been shown that, although rectification is impossible at equilibrium, it is possible for the Feynman-micromotor to perform work under non-equilibrium conditions. These concepts can now be realized by MEMS technology and may have exciting implications in biomedicine - where the Feynman- micromotor can be used to power a smart pill, for example. Previously, Feynman's analysis of the motor's efficiency has been shown to be flawed by Parrondo and Espanol. We now show there are further problems in Feynman's treatment of detailed balance. In order to design and understand this device correctly, the equations of detailed balance must be found. Feynman's approach was to use probabilities based on energies and we show that this is problematic. In this paper, we demonstrate corrected equations using level crossing probabilities instead. A potential application of the Feynman-micromotor is a batteryless nanopump that consists of a small MEMS chip that adheres to the skin of a patient and dispense nanoliter quantities of medication. Either mechanical or thermal rectification via a Feynman- micromotor, as the power source, is open for possible investigation.

  18. Feasibility and outcomes of the Berg Balance Scale in older adults with intellectual disabilities

    NARCIS (Netherlands)

    Oppewal, Alyt; Hilgenkamp, Thessa I. M.; van Wijck, Ruud; Evenhuis, Heleen M.

    High incidence of falls and increased risk of fall-related injuries are seen in individuals with intellectual disabilities (ID). The Berg Balance Scale (BBS) is a reliable instrument for balance assessment in the population of (older) adults with ID. The aims of this study were to assess the balance

  19. Numerical bifurcation analysis of a class of nonlinear renewal equations

    NARCIS (Netherlands)

    Breda, Dimitri; Diekmann, Odo; Liessi, Davide; Scarabel, Francesca

    2016-01-01

    We show, by way of an example, that numerical bifurcation tools for ODE yield reliable bifurcation diagrams when applied to the pseudospectral approximation of a one-parameter family of nonlinear renewal equations. The example resembles logistic-and Ricker-type population equations and exhibits

  20. Calculating the water and heat balances of the Eastern Mediterranean Basin using ocean modelling and available meteorological, hydrological and ocean data

    Directory of Open Access Journals (Sweden)

    Anders Omstedt

    2012-04-01

    Full Text Available Eastern Mediterranean water and heat balances wereanalysed over 52 years. The modelling uses a process-orientedapproach resolving the one-dimensional equations of momentum,heat and salt conservation; turbulence is modelled using a two-equation model. The results indicate that calculated temperature and salinity follow the reanalysed data well. The water balance in the Eastern Mediterranean basin was controlled by the difference between inflows and outflows through the Sicily Channel and by net precipitation. The freshwater component displayed a negative trend over the study period, indicating increasing salinity in the basin.The heat balance was controlled by heat loss from the water surface, solar radiation into the sea and heat flow through the Sicily Channel. Both solar radiation and net heat loss displayed increasing trends, probably due to decreased total cloud cover. In addition, the heat balance indicated a net import of approximately 9 W m-2 of heat to the Eastern Mediterranean Basin from the Western Basin.

  1. Searching fundamental information in ordinary differential equations. Nondimensionalization technique.

    Science.gov (United States)

    Sánchez Pérez, J F; Conesa, M; Alhama, I; Alhama, F; Cánovas, M

    2017-01-01

    Classical dimensional analysis and nondimensionalization are assumed to be two similar approaches in the search for dimensionless groups. Both techniques, simplify the study of many problems. The first approach does not need to know the mathematical model, being sufficient a deep understanding of the physical phenomenon involved, while the second one begins with the governing equations and reduces them to their dimensionless form by simple mathematical manipulations. In this work, a formal protocol is proposed for applying the nondimensionalization process to ordinary differential equations, linear or not, leading to dimensionless normalized equations from which the resulting dimensionless groups have two inherent properties: In one hand, they are physically interpreted as balances between counteracting quantities in the problem, and on the other hand, they are of the order of magnitude unity. The solutions provided by nondimensionalization are more precise in every case than those from dimensional analysis, as it is illustrated by the applications studied in this work.

  2. Analysis of spectral methods for the homogeneous Boltzmann equation

    KAUST Repository

    Filbet, Francis; Mouhot, Clé ment

    2011-01-01

    The development of accurate and fast algorithms for the Boltzmann collision integral and their analysis represent a challenging problem in scientific computing and numerical analysis. Recently, several works were devoted to the derivation of spectrally accurate schemes for the Boltzmann equation, but very few of them were concerned with the stability analysis of the method. In particular there was no result of stability except when the method was modified in order to enforce the positivity preservation, which destroys the spectral accuracy. In this paper we propose a new method to study the stability of homogeneous Boltzmann equations perturbed by smoothed balanced operators which do not preserve positivity of the distribution. This method takes advantage of the "spreading" property of the collision, together with estimates on regularity and entropy production. As an application we prove stability and convergence of spectral methods for the Boltzmann equation, when the discretization parameter is large enough (with explicit bound). © 2010 American Mathematical Society.

  3. Analysis of spectral methods for the homogeneous Boltzmann equation

    KAUST Repository

    Filbet, Francis

    2011-04-01

    The development of accurate and fast algorithms for the Boltzmann collision integral and their analysis represent a challenging problem in scientific computing and numerical analysis. Recently, several works were devoted to the derivation of spectrally accurate schemes for the Boltzmann equation, but very few of them were concerned with the stability analysis of the method. In particular there was no result of stability except when the method was modified in order to enforce the positivity preservation, which destroys the spectral accuracy. In this paper we propose a new method to study the stability of homogeneous Boltzmann equations perturbed by smoothed balanced operators which do not preserve positivity of the distribution. This method takes advantage of the "spreading" property of the collision, together with estimates on regularity and entropy production. As an application we prove stability and convergence of spectral methods for the Boltzmann equation, when the discretization parameter is large enough (with explicit bound). © 2010 American Mathematical Society.

  4. Generating a Multiphase Equation of State with Swarm Intelligence

    Science.gov (United States)

    Cox, Geoffrey

    2017-06-01

    Hydrocode calculations require knowledge of the variation of pressure of a material with density and temperature, which is given by the equation of state. An accurate model needs to account for discontinuities in energy, density and properties of a material across a phase boundary. When generating a multiphase equation of state the modeller attempts to balance the agreement between the available data for compression, expansion and phase boundary location. However, this can prove difficult because minor adjustments in the equation of state for a single phase can have a large impact on the overall phase diagram. Recently, Cox and Christie described a method for combining statistical-mechanics-based condensed matter physics models with a stochastic analysis technique called particle swarm optimisation. The models produced show good agreement with experiment over a wide range of pressure-temperature space. This talk details the general implementation of this technique, shows example results, and describes the types of analysis that can be performed with this method.

  5. A contribution to the validation of the Wii Balance Board for the assessment of standing balance.

    Science.gov (United States)

    Pavan, Piero; Cardaioli, Matteo; Ferri, Ilaria; Gobbi, Erica; Carraro, Attilio

    2015-01-01

    Valid and reliable accessible measures of balance are required in a health-related fitness test battery, both in the general population and in groups with special needs. For this purpose, the capability of the Wii Balance Board (WBB) in evaluating standing balance was analysed and compared with a laboratory-graded force platform (FP). A 30-s double limb standing test with open and closed eyes was performed by 28 individuals (12 male and 16 female, mean age = 23.8, SD = ±2.7 years). A simple method of acquisition of the centre of pressure (CoP) over time was applied to compare WBB and FP simultaneously on the same signal. User-defined software was developed to obtain the CoP from WBB over time and the resulting related measures and graphical representations. The comparison of measures, such as sway path and maximum oscillations along the anterior-posterior and medial-lateral direction, obtained with the FP and the WBB shows that the latter, in conjunction with the user-defined developed software, can be appropriate, considering prescribed limits, and an easy-to-use tool for evaluating standing balance.

  6. WENO schemes for balance laws with spatially varying flux

    International Nuclear Information System (INIS)

    Vukovic, Senka; Crnjaric-Zic, Nelida; Sopta, Luka

    2004-01-01

    In this paper we construct numerical schemes of high order of accuracy for hyperbolic balance law systems with spatially variable flux function and a source term of the geometrical type. We start with the original finite difference characteristicwise weighted essentially nonoscillatory (WENO) schemes and then we create new schemes by modifying the flux formulations (locally Lax-Friedrichs and Roe with entropy fix) in order to account for the spatially variable flux, and by decomposing the source term in order to obtain balance between numerical approximations of the flux gradient and of the source term. We apply so extended WENO schemes to the one-dimensional open channel flow equations and to the one-dimensional elastic wave equations. In particular, we prove that in these applications the new schemes are exactly consistent with steady-state solutions from an appropriately chosen subset. Experimentally obtained orders of accuracy of the extended and original WENO schemes are almost identical on a convergence test. Other presented test problems illustrate the improvement of the proposed schemes relative to the original WENO schemes combined with the pointwise source term evaluation. As expected, the increase in the formal order of accuracy of applied WENO reconstructions in all the tests causes visible increase in the high resolution properties of the schemes

  7. Stochastic dynamics and logistic population growth

    Science.gov (United States)

    Méndez, Vicenç; Assaf, Michael; Campos, Daniel; Horsthemke, Werner

    2015-06-01

    The Verhulst model is probably the best known macroscopic rate equation in population ecology. It depends on two parameters, the intrinsic growth rate and the carrying capacity. These parameters can be estimated for different populations and are related to the reproductive fitness and the competition for limited resources, respectively. We investigate analytically and numerically the simplest possible microscopic scenarios that give rise to the logistic equation in the deterministic mean-field limit. We provide a definition of the two parameters of the Verhulst equation in terms of microscopic parameters. In addition, we derive the conditions for extinction or persistence of the population by employing either the momentum-space spectral theory or the real-space Wentzel-Kramers-Brillouin approximation to determine the probability distribution function and the mean time to extinction of the population. Our analytical results agree well with numerical simulations.

  8. A Simplification for Exp-Function Method When the Balanced Nonlinear Term Is a Certain Product

    Directory of Open Access Journals (Sweden)

    Hong-Zhun Liu

    2013-01-01

    Full Text Available The Exp-function method plays an important role in searching for analytic solutions of many nonlinear differential equations. In this paper, we prove that the balancing procedure in the method is unnecessary when the balanced nonlinear term is a product of the dependent variable under consideration and its derivatives. And in this case, the ansatz of the method can be simplified to be with less parameters so as to be easy to calculate.

  9. Large Scale Simulation of Hydrogen Dispersion by a Stabilized Balancing Domain Decomposition Method

    Directory of Open Access Journals (Sweden)

    Qing-He Yao

    2014-01-01

    Full Text Available The dispersion behaviour of leaking hydrogen in a partially open space is simulated by a balancing domain decomposition method in this work. An analogy of the Boussinesq approximation is employed to describe the connection between the flow field and the concentration field. The linear systems of Navier-Stokes equations and the convection diffusion equation are symmetrized by a pressure stabilized Lagrange-Galerkin method, and thus a balancing domain decomposition method is enabled to solve the interface problem of the domain decomposition system. Numerical results are validated by comparing with the experimental data and available numerical results. The dilution effect of ventilation is investigated, especially at the doors, where flow pattern is complicated and oscillations appear in the past research reported by other researchers. The transient behaviour of hydrogen and the process of accumulation in the partially open space are discussed, and more details are revealed by large scale computation.

  10. Nonlinear Fokker-Planck Equations Fundamentals and Applications

    CERN Document Server

    Frank, Till Daniel

    2005-01-01

    Providing an introduction to the theory of nonlinear Fokker-Planck equations, this book discusses fundamental properties of transient and stationary solutions, emphasizing the stability analysis of stationary solutions by means of self-consistency equations, linear stability analysis, and Lyapunov's direct method. Also treated are Langevin equations and correlation functions. Nonlinear Fokker-Planck Equations addresses various phenomena such as phase transitions, multistability of systems, synchronization, anomalous diffusion, cut-off solutions, travelling-wave solutions and the emergence of power law solutions. A nonlinear Fokker-Planck perspective to quantum statistics, generalized thermodynamics, and linear nonequilibrium thermodynamics is given. Theoretical concepts are illustrated where possible by simple examples. The book also reviews several applications in the fields of condensed matter physics, the physics of porous media and liquid crystals, accelerator physics, neurophysics, social sciences, popul...

  11. Three-dimensional wave-induced current model equations and radiation stresses

    Science.gov (United States)

    Xia, Hua-yong

    2017-08-01

    After the approach by Mellor (2003, 2008), the present paper reports on a repeated effort to derive the equations for three-dimensional wave-induced current. Via the vertical momentum equation and a proper coordinate transformation, the phase-averaged wave dynamic pressure is well treated, and a continuous and depth-dependent radiation stress tensor, rather than the controversial delta Dirac function at the surface shown in Mellor (2008), is provided. Besides, a phase-averaged vertical momentum flux over a sloping bottom is introduced. All the inconsistencies in Mellor (2003, 2008), pointed out by Ardhuin et al. (2008) and Bennis and Ardhuin (2011), are overcome in the presently revised equations. In a test case with a sloping sea bed, as shown in Ardhuin et al. (2008), the wave-driving forces derived in the present equations are in good balance, and no spurious vertical circulation occurs outside the surf zone, indicating that Airy's wave theory and the approach of Mellor (2003, 2008) are applicable for the derivation of the wave-induced current model.

  12. CORRECTION OF FORECASTS OF INTERRELATED CURRENCY PAIRS IN TERMS OF SYSTEMS OF BALANCE RATIOS

    OpenAIRE

    Gertsekovich D. A.

    2015-01-01

    In this paper the problem of exchange rates forecast is logically considered a) traditionally as a task of forecast on the base of «stand-alone» equations of autoregression for each currency pair and b) as a result of forecast correction of autoregression equations system on the base of boundary conditions of balance ratios systems. As a criterion for quality of forecast constructed with empirical models we take the sum of deficiency quadrates of forecasts estimated for deductive currency pai...

  13. SUPPORTING STUDENTS’ UNDERSTANDING OF LINEAR EQUATIONS WITH ONE VARIABLE USING ALGEBRA TILES

    Directory of Open Access Journals (Sweden)

    Sari Saraswati

    2016-01-01

    Full Text Available This research aimed to describe how algebra tiles can support students’ understanding of linear equations with one variable. This article is a part of a larger research on learning design of linear equations with one variable using algebra tiles combined with balancing method. Therefore, it will merely discuss one activity focused on how students use the algebra tiles to find a method to solve linear equations with one variable. Design research was used as an approach in this study. It consists of three phases, namely preliminary design, teaching experiment and retrospective analysis. Video registrations, students’ written works, pre-test, post-test, field notes, and interview are technic to collect data. The data were analyzed by comparing the hypothetical learning trajectory (HLT and the actual learning process. The result shows that algebra tiles could supports students’ understanding to find the formal solution of linear equation with one variable.

  14. The Effects of a Postural Balance Training Program on Balance, Gait and Health-Related Quality of Life in Patients with Essential Tremor

    Directory of Open Access Journals (Sweden)

    Bilge Kara

    2018-03-01

    Full Text Available Objective: Although the effectiveness of postural balance training on balance and gait impairment has been proven as an effective treatment approach in several patient and healthy populations, its effectiveness in patients with essential tremor (ET is yet unknown. The aim was to examine the effects of postural balance training program on balance and gait performance, and health-related quality of life in patients with ET. Materials and Methods: This uncontrolled clinical study included patients with ET. The outcome measures were the Postural Stability Test, Limits of Stability Test, Fall Risk Test, Activities-Specific Balance Confidence scale, Dynamic Gait Index, and Short Form-36. The assessments were performed before and after the training program. The participants underwent an 8-week balance training designed to improve their ability to integrate multisensory inputs and postural control using a computerized balance assessment and training device. Results: In total, 24 patients with ET participated in the study. The compliance rate was 87.5%. There were significant improvements in all outcome measures of balance and gait performance, balance confidence, fall risk, and health-related quality of life (except the mental component, p>0.05 between baseline and 8 weeks (p<0.05. Conclusion: Our results suggest that the balance training program is a feasible method that may have positive effects on balance performance and confidence, gait performance, and health-related quality of life in patients with ET

  15. A Population of Assessment Tasks

    Science.gov (United States)

    Daro, Phil; Burkhardt, Hugh

    2012-01-01

    We propose the development of a "population" of high-quality assessment tasks that cover the performance goals set out in the "Common Core State Standards for Mathematics." The population will be published. Tests are drawn from this population as a structured random sample guided by a "balancing algorithm."

  16. BALANCE

    Science.gov (United States)

    Carmichael, H.

    1953-01-01

    A torsional-type analytical balance designed to arrive at its equilibrium point more quickly than previous balances is described. In order to prevent external heat sources creating air currents inside the balance casing that would reiard the attainment of equilibrium conditions, a relatively thick casing shaped as an inverted U is placed over the load support arms and the balance beam. This casing is of a metal of good thernnal conductivity characteristics, such as copper or aluminum, in order that heat applied to one portion of the balance is quickly conducted to all other sensitive areas, thus effectively preventing the fornnation of air currents caused by unequal heating of the balance.

  17. Differential Equations Compatible with KZ Equations

    International Nuclear Information System (INIS)

    Felder, G.; Markov, Y.; Tarasov, V.; Varchenko, A.

    2000-01-01

    We define a system of 'dynamical' differential equations compatible with the KZ differential equations. The KZ differential equations are associated to a complex simple Lie algebra g. These are equations on a function of n complex variables z i taking values in the tensor product of n finite dimensional g-modules. The KZ equations depend on the 'dual' variable in the Cartan subalgebra of g. The dynamical differential equations are differential equations with respect to the dual variable. We prove that the standard hypergeometric solutions of the KZ equations also satisfy the dynamical equations. As an application we give a new determinant formula for the coordinates of a basis of hypergeometric solutions

  18. Clinical measures of balance in people with type two diabetes: A systematic literature review.

    Science.gov (United States)

    Dixon, C J; Knight, T; Binns, E; Ihaka, B; O'Brien, D

    2017-10-01

    Approximately 422 million people have diabetes mellitus worldwide, with the majority diagnosed with type 2 diabetes mellitus (T2DM). The complications of diabetes mellitus include diabetic peripheral neuropathy (DPN) and retinopathy, both of which can lead to balance impairments. Balance assessment is therefore an integral component of the clinical assessment of a person with T2DM. Although there are a variety of balance measures available, it is uncertain which measures are the most appropriate for this population. Therefore, the aim of this study was to conduct a systematic review on clinical balance measures used with people with T2DM and DPN. Databases searched included: CINAHL plus, MEDLINE, SPORTDiscus, Dentistry and Oral Sciences source, and SCOPUS. Key terms, inclusion and exclusion criteria were used to identify appropriate studies. Identified studies were critiqued using the Downs and Black appraisal tool. Eight studies were included, these studies incorporated a total of ten different clinical balance measures. The balance measures identified included the Dynamic Balance Test, balance walk, tandem and unipedal stance, Functional Reach Test, Clinical Test of Sensory Interaction and Balance, Berg Balance Scale, Tinetti Performance-Oriented Mobility Assessment, Activity-Specific Balance Confidence Scale, Timed Up and Go test, and the Dynamic Gait Index. Numerous clinical balance measures were used for people with T2DM. However, the identified balance measures did not assess all of the systems of balance, and most had not been validated in a T2DM population. Therefore, future research is needed to identify the validity of a balance measure that assesses these systems in people with T2DM. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  19. Continental-scale footprint of balancing and positive selection in a small rodent (Microtus arvalis.

    Directory of Open Access Journals (Sweden)

    Martin C Fischer

    Full Text Available Genetic adaptation to different environmental conditions is expected to lead to large differences between populations at selected loci, thus providing a signature of positive selection. Whereas balancing selection can maintain polymorphisms over long evolutionary periods and even geographic scale, thus leads to low levels of divergence between populations at selected loci. However, little is known about the relative importance of these two selective forces in shaping genomic diversity, partly due to difficulties in recognizing balancing selection in species showing low levels of differentiation. Here we address this problem by studying genomic diversity in the European common vole (Microtus arvalis presenting high levels of differentiation between populations (average F ST = 0.31. We studied 3,839 Amplified Fragment Length Polymorphism (AFLP markers genotyped in 444 individuals from 21 populations distributed across the European continent and hence over different environmental conditions. Our statistical approach to detect markers under selection is based on a Bayesian method specifically developed for AFLP markers, which treats AFLPs as a nearly codominant marker system, and therefore has increased power to detect selection. The high number of screened populations allowed us to detect the signature of balancing selection across a large geographic area. We detected 33 markers potentially under balancing selection, hence strong evidence of stabilizing selection in 21 populations across Europe. However, our analyses identified four-times more markers (138 being under positive selection, and geographical patterns suggest that some of these markers are probably associated with alpine regions, which seem to have environmental conditions that favour adaptation. We conclude that despite favourable conditions in this study for the detection of balancing selection, this evolutionary force seems to play a relatively minor role in shaping the genomic

  20. Approximate solution to the Kolmogorov equation for a fission chain-reacting system

    International Nuclear Information System (INIS)

    Ruby, L.; McSwine, T.L.

    1986-01-01

    An approximate solution has been obtained for the Kolmogorov equation describing a fission chain-reacting system. The method considers the population of neutrons, delayed-neutron precursors, and detector counts. The effect of the detector is separated from the statistics of the chain reaction by a weak coupling assumption that predicts that the detector responds to the average rather than to the instantaneous neutron population. An approximate solution to the remaining equation, involving the populations of neutrons and precursors, predicts a negative-binomial behaviour for the neutron probability distribution

  1. Testing the transferability of regression equations derived from small sub-catchments to a large area in central Sweden

    Directory of Open Access Journals (Sweden)

    C. Xu

    2003-01-01

    Full Text Available There is an ever increasing need to apply hydrological models to catchments where streamflow data are unavailable or to large geographical regions where calibration is not feasible. Estimation of model parameters from spatial physical data is the key issue in the development and application of hydrological models at various scales. To investigate the suitability of transferring the regression equations relating model parameters to physical characteristics developed from small sub-catchments to a large region for estimating model parameters, a conceptual snow and water balance model was optimised on all the sub-catchments in the region. A multiple regression analysis related model parameters to physical data for the catchments and the regression equations derived from the small sub-catchments were used to calculate regional parameter values for the large basin using spatially aggregated physical data. For the model tested, the results support the suitability of transferring the regression equations to the larger region. Keywords: water balance modelling,large scale, multiple regression, regionalisation

  2. Energy balance for a dissipative quantum system

    International Nuclear Information System (INIS)

    Kumar, Jishad

    2014-01-01

    The role of random force in maintaining equilibrium in a dissipative quantum system is studied here. We compute the instantaneous power supplied by the fluctuating (random) force, which provides information about the work done by the random force on the quantum subsystem of interest. The quantum Langevin equation formalism is used here to verify that, at equilibrium, the work done by the fluctuating force balances the energy lost by the quantum subsystem to the heat bath. The quantum subsystem we choose to couple to the heat bath is the charged oscillator in a magnetic field. We perform the calculations using the Drude regularized spectral density of bath oscillators instead of using a strict ohmic spectral density that gives memoryless damping. We also discuss the energy balance for our dissipative quantum system and in this regard it is to be understood that the physical system is the charged magneto-oscillator coupled to the heat bath, not the uncoupled charged magneto-oscillator. (paper)

  3. Electronic Health Record Effects on Work-Life Balance and Burnout Within the I3 Population Collaborative.

    Science.gov (United States)

    Robertson, Sandy L; Robinson, Mark D; Reid, Alfred

    2017-08-01

    Physician burnout is a problem that often is attributed to the use of the electronic health record (EHR). To estimate the prevalence of burnout and work-life balance satisfaction in primary care residents and teaching physicians, and to examine the relationship between these outcomes, EHR use, and other practice and individual factors. Residents and faculty in 19 primary care programs were anonymously surveyed about burnout, work-life balance satisfaction, and EHR use. Additional items included practice size, specialty, EHR characteristics, and demographics. A logistic regression model identified independent factors associated with burnout and work-life balance satisfaction. In total, 585 of 866 surveys (68%) were completed, and 216 (37%) respondents indicated 1 or more symptoms of burnout, with 162 (75%) attributing burnout to the EHR. A total of 310 of 585 (53%) reported dissatisfaction with work-life balance, and 497 (85%) indicated that use of the EHR affected their work-life balance. Respondents who spent more than 6 hours weekly after hours in EHR work were 2.9 times (95% confidence interval [CI] 1.9-4.4) more likely to report burnout and 3.9 times (95% CI 1.9-8.2) more likely to attribute burnout to the EHR. They were 0.33 times (95% CI 0.22-0.49) as likely to report work-life balance satisfaction, and 3.7 times (95% CI 2.1-6.7) more likely to attribute their work-life balance satisfaction to the EHR. More after-hours time spent on the EHR was associated with burnout and less work-life satisfaction in primary care residents and faculty.

  4. Sustaining a world in balance.

    Science.gov (United States)

    1992-04-01

    The world balance of population and resources is the internationally accepted goal for the 20th century. There is agreement that the requirements are elimination of absolute poverty, the legitimate satisfaction of the majority population, reduction in the environmental cost of development, fairer distribution of the benefits of development, slower population growth, and more balanced distribution within and between countries. A profile is given for 15 development and population measures for the Philippines. In the Philippines over 50% of the population lives in poverty, and the numbers are increasing. Unemployment is high at 10.6% in 1991, and underemployment is estimated to be 31.6%. Limited employment opportunities are push factors for international labor migration, which has swelled to over 600,000 workers. The Philippines is losing forest at the rate of about 119,000 hectares per year, which would result in a total loss of forests in 12 years. The loss of biodiversity is apparent. Marine resources are being depleted, and average farm size per rural person is 0.38 hectares. The average family of 6 persons must produce food on only 2.28 hectares. The annual population growth rate is 2.3%, and the rate of food production is only 1%. Metro Manila is now the 18th largest urban area in the world. Air pollution is very high, and the water supply is polluted with salt. 14% of children under 6 years old are severely underweight. Iron deficiency anemia affects 60% of children 1-6 years old and 40% of children 7-12 years old. 3.5 million children are working, and 20,000 are child prostitutes. 85,000 street children live in 17 cities. Maternal mortality is estimated at 1600 women each year, and 24% of deaths in 78 hospitals were due to induced abortion. About 2.7 million women have unmet need for family planning, and 1.8 million desire family planning but are not using any method.

  5. Discovering governing equations from data by sparse identification of nonlinear dynamics

    Science.gov (United States)

    Brunton, Steven

    The ability to discover physical laws and governing equations from data is one of humankind's greatest intellectual achievements. A quantitative understanding of dynamic constraints and balances in nature has facilitated rapid development of knowledge and enabled advanced technology, including aircraft, combustion engines, satellites, and electrical power. There are many more critical data-driven problems, such as understanding cognition from neural recordings, inferring patterns in climate, determining stability of financial markets, predicting and suppressing the spread of disease, and controlling turbulence for greener transportation and energy. With abundant data and elusive laws, data-driven discovery of dynamics will continue to play an increasingly important role in these efforts. This work develops a general framework to discover the governing equations underlying a dynamical system simply from data measurements, leveraging advances in sparsity-promoting techniques and machine learning. The resulting models are parsimonious, balancing model complexity with descriptive ability while avoiding overfitting. The only assumption about the structure of the model is that there are only a few important terms that govern the dynamics, so that the equations are sparse in the space of possible functions. This perspective, combining dynamical systems with machine learning and sparse sensing, is explored with the overarching goal of real-time closed-loop feedback control of complex systems. This is joint work with Joshua L. Proctor and J. Nathan Kutz. Video Abstract: https://www.youtube.com/watch?v=gSCa78TIldg

  6. Population activity structure of excitatory and inhibitory neurons.

    Science.gov (United States)

    Bittner, Sean R; Williamson, Ryan C; Snyder, Adam C; Litwin-Kumar, Ashok; Doiron, Brent; Chase, Steven M; Smith, Matthew A; Yu, Byron M

    2017-01-01

    Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure.

  7. Population activity structure of excitatory and inhibitory neurons.

    Directory of Open Access Journals (Sweden)

    Sean R Bittner

    Full Text Available Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure.

  8. Population activity structure of excitatory and inhibitory neurons

    Science.gov (United States)

    Doiron, Brent

    2017-01-01

    Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure. PMID:28817581

  9. Maintaining balance in elderly fallers: novel aspects of postural balance measures in elderly

    OpenAIRE

    Swanenburg, Jaap

    2009-01-01

    At first in this thesis, an intervention programme was tested for the effect on the risk of falling in a population of elderly. The aim of the study was to investigate if exercise, combined with protein intake and calcium/vitamin D supplementation would have a larger effect on the risk of falling and postural balance outcomes than calcium/vitamin D supplementation only. An observational performance test (risk of falling) and performance measurements (force platform) were used as outcome measu...

  10. Evaluation of a mass-balance approach to determine consumptive water use in northeastern Illinois

    Science.gov (United States)

    Mills, Patrick C.; Duncker, James J.; Over, Thomas M.; Marian Domanski,; ,; Engel, Frank

    2014-01-01

    A principal component of evaluating and managing water use is consumptive use. This is the portion of water withdrawn for a particular use, such as residential, which is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. The amount of consumptive use may be estimated by a water (mass)-balance approach; however, because of the difficulty of obtaining necessary data, its application typically is restricted to the facility scale. The general governing mass-balance equation is: Consumptive use = Water supplied - Return flows.

  11. Prospective identification of malaria parasite genes under balancing selection.

    Directory of Open Access Journals (Sweden)

    Kevin K A Tetteh

    Full Text Available Endemic human pathogens are subject to strong immune selection, and interrogation of pathogen genome variation for signatures of balancing selection can identify important target antigens. Several major antigen genes in the malaria parasite Plasmodium falciparum have shown such signatures in polymorphism-versus-divergence indices (comparing with the chimpanzee parasite P. reichenowi, and in allele frequency based indices.To compare methods for prospective identification of genes under balancing selection, 26 additional genes known or predicted to encode surface-exposed proteins of the invasive blood stage merozoite were first sequenced from a panel of 14 independent P. falciparum cultured lines and P. reichenowi. Six genes at the positive extremes of one or both of the Hudson-Kreitman-Aguade (HKA and McDonald-Kreitman (MK indices were identified. Allele frequency based analysis was then performed on a Gambian P. falciparum population sample for these six genes and three others as controls. Tajima's D (TjD index was most highly positive for the msp3/6-like PF10_0348 (TjD = 1.96 as well as the positive control ama1 antigen gene (TjD = 1.22. Across the genes there was a strong correlation between population TjD values and the relative HKA indices (whether derived from the population or the panel of cultured laboratory isolates, but no correlation with the MK indices.Although few individual parasite genes show significant evidence of balancing selection, analysis of population genomic and comparative sequence data with the HKA and TjD indices should discriminate those that do, and thereby identify likely targets of immunity.

  12. Balanced and Unbalanced Circulations in a Primitive Equation Simulation of a Midlatitude MCC. Part I: The Numerical Simulation.

    Science.gov (United States)

    Olsson, Peter Q.; Cotton, William R.

    1997-02-01

    banded vorticity structure at midtropospheric levels. These bands were found to be due to the apparent vertical transport of zonal momentum by the descending rear-to-front circulation, or rear-inflow jet. An equivalent alternative viewpoint of this process, deformation of horizontal vorticity filaments by the convective updrafts and rear-inflow jet, is discussed.Part II of this work presents a complementary approach to the analysis presented here, demonstrating that the circulations seen in this MCC simulation are, to a large degree, contained within the nonlinear balance approximation, the related balanced omega equation, and the PV as analyzed from the PE model results.

  13. The Energy Balance Study: The Design and Baseline Results for a Longitudinal Study of Energy Balance

    Science.gov (United States)

    Hand, Gregory A.; Shook, Robin P.; Paluch, Amanda E.; Baruth, Meghan; Crowley, E. Patrick; Jaggers, Jason R.; Prasad, Vivek K.; Hurley, Thomas G.; Hebert, James R.; O'Connor, Daniel P.; Archer, Edward; Burgess, Stephanie; Blair, Steven N.

    2013-01-01

    Purpose: The Energy Balance Study (EBS) was a comprehensive study designed to determine over a period of 12 months the associations of caloric intake and energy expenditure on changes in body weight and composition in a population of healthy men and women. Method: EBS recruited men and women aged 21 to 35 years with a body mass index between 20…

  14. Resolution of the time dependent P{sub n} equations by a Godunov type scheme having the diffusion limit; Resolution des equations P{sub n} instationnaires par un schema de type Godunov, ayant la limite diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Cargo, P.; Samba, G

    2007-07-01

    We consider the P{sub n} model to approximate the transport equation in one dimension of space. In a diffusive regime, the solution of this system is solution of a diffusion equation. We are looking for a numerical scheme having the diffusion limit property: in a diffusive regime, it gives the solution of the limiting diffusion equation on a mesh at the diffusion scale. The numerical scheme proposed is an extension of the Godunov type scheme proposed by L. Gosse to solve the P{sub 1} model without absorption term. Moreover, it has the well-balanced property: it preserves the steady solutions of the system. (authors)

  15. Controlling Population with Pollution

    Science.gov (United States)

    Browne, Joseph

    2010-01-01

    Population models are often discussed in algebra, calculus, and differential equations courses. In this article we will use the human population of the world as our application. After quick looks at two common models we'll investigate more deeply a model which incorporates the negative effect that accumulated pollution may have on population.

  16. Wave equations for pulse propagation

    International Nuclear Information System (INIS)

    Shore, B.W.

    1987-01-01

    Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity. The memo discusses various ways of characterizing the polarization characteristics of plane waves, that is, of parameterizing a transverse unit vector, such as the Jones vector, the Stokes vector, and the Poincare sphere. It discusses the connection between macroscopically defined quantities, such as the intensity or, more generally, the Stokes parameters, and microscopic field amplitudes. The material presented here is a portion of a more extensive treatment of propagation to be presented separately. The equations presented here have been described in various books and articles. They are collected here as a summary and review of theory needed when treating pulse propagation

  17. Autobalancing of a rigid rotor in viscoelastic orthotropic supports considering eccentricity of the automatic ball balancer

    Science.gov (United States)

    Bykov, V. G.; Kovachev, A. S.

    2018-05-01

    A statically unbalanced rotor in viscoelastic orthotropic supports equipped with an automatic ball balancer (ABB), the axis of symmetry of which does not coincide with the symmetry axis of the rotor, is considered. Based on an analysis of the equations describing the stationary modes of motion of the system, the principal impossibility of complete balancing of the rotor is shown. The possibility of the existence of two types of stationary modes is established, one of which has a constant average amplitude of residual vibration equal to the eccentricity of the ABB. The solution corresponding to this almost balanced mode is constructed analytically. A study is made of its asymptotic stability.

  18. Development of standard weight equations for Caribbean and Gulf of Mexico amphidromous fishes

    Science.gov (United States)

    Cooney, Patrick B.; Kwak, Thomas J.

    2010-01-01

    We collected and compiled length and weight information from four countries and one commonwealth to develop standard weight (Ws) equations for three amphidromous fish species native to the Caribbean and Gulf of Mexico regions: mountain mullet Agonostomus monticola (N = 9,768 individuals, 52 populations), river goby Awaous banana (N = 1,847 individuals, 62 populations), and bigmouth sleeper Gobiomorus dormitor (N = 2,983 individuals, 53 populations). Linear and quadratic Ws equations for three quartiles (25%, median, 75%) are presented for these three species. The length-weight relationship from eight lentic bigmouth sleeper populations was significantly different from that of lotic populations, reflecting higher weights of juvenile fish (sport fisheries and allow ecological assessment based on fish condition.

  19. Estimating glomerular filtration rate in a population-based study

    Directory of Open Access Journals (Sweden)

    Anoop Shankar

    2010-07-01

    Full Text Available Anoop Shankar1, Kristine E Lee2, Barbara EK Klein2, Paul Muntner3, Peter C Brazy4, Karen J Cruickshanks2,5, F Javier Nieto5, Lorraine G Danforth2, Carla R Schubert2,5, Michael Y Tsai6, Ronald Klein21Department of Community Medicine, West Virginia University School of Medicine, Morgantown, WV, USA; 2Department of Ophthalmology and Visual Sciences, 4Department of Medicine, 5Department of Population Health Sciences, University of Wisconsin, School of Medicine and Public Health, Madison, WI, USA; 3Department of Community Medicine, Mount Sinai School of Medicine, NY, USA; 6Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USABackground: Glomerular filtration rate (GFR-estimating equations are used to determine the prevalence of chronic kidney disease (CKD in population-based studies. However, it has been suggested that since the commonly used GFR equations were originally developed from samples of patients with CKD, they underestimate GFR in healthy populations. Few studies have made side-by-side comparisons of the effect of various estimating equations on the prevalence estimates of CKD in a general population sample.Patients and methods: We examined a population-based sample comprising adults from Wisconsin (age, 43–86 years; 56% women. We compared the prevalence of CKD, defined as a GFR of <60 mL/min per 1.73 m2 estimated from serum creatinine, by applying various commonly used equations including the modification of diet in renal disease (MDRD equation, Cockcroft–Gault (CG equation, and the Mayo equation. We compared the performance of these equations against the CKD definition of cystatin C >1.23 mg/L.Results: We found that the prevalence of CKD varied widely among different GFR equations. Although the prevalence of CKD was 17.2% with the MDRD equation and 16.5% with the CG equation, it was only 4.8% with the Mayo equation. Only 24% of those identified to have GFR in the range of 50–59 mL/min per 1

  20. The Shifting Global Power Balance Equations and the Emerging Real ‘New World Order’

    OpenAIRE

    Ovie-D’Leone, Alex Igho

    2010-01-01

    Expansion in globalization arising from increased interconnectivity and interdependence across the worldis causing a shift both in the focus of what now could determine the principal international powervariables and the criteria for power balancing calculus. One direct challenge to the status quo is theemergence on one hand of new state actors which are becoming more assertive, as well as some other newkey non-state actors now matching states seemingly one-on-one on the world stage in many sp...

  1. Evaluation of water balance in a population of older adults. A case control study.

    Science.gov (United States)

    Malisova, Olga; Poulia, Kalliopi-Anna; Kolyzoi, Kleoniki; Lysandropoulos, Athanasios; Sfendouraki, Kalliopi; Kapsokefalou, Maria

    2018-04-01

    Older adults are at risk for dehydration and its' potentially life-threatening consequences. Unrecognized dehydration can complicate chronic medical problems and increase morbidity. The objective of the study was to estimate water balance, intake and loss in elderly people living in Greece using the Water Balance Questionnaire (WBQ). WBQ was administered in winter to 108 independents (65-81yrs) (Group A), 94 independents (82-92yrs) (Group B) and 51 hospitalized (65-92yrs) (Group C). A database from previous study of 335 adults (18-65yrs) (Control Group) used for comparison. Mean estimates of water balance, intake and loss were, respectively, for Group A -749 ± 1386 mL/day, 2571 ± 739 mL/day and 3320 ± 1216 mL/day, for Group B -38 ± 933 mL/day, 2571 ± 739 mL/day and 3320 ± 1216 mL/day, for Group C 64 ± 1399 mL/day, 2586 ± 1071 mL/day and 2522 ± 1048 mL/day and for Control Group -253 ± 1495 mL/day, 2912 ± 1025 mL/day and 3492 ± 2099 mL/day. Significant differences were detected in water balance, intake and loss (p < 0.01). Water balance and water intake in Group A was the lowest. For Groups A, B, C and Control, contribution of solid foods to water intake was 36%, 29%, 32%, 25%, of drinking water was 32%, 48%, 45%, 47%, of beverages was 32%, 23%, 23% and 28% respectively. Significant differences observed in the contribution of drinking water and beverages (p < 0.01). Group A had lower water balance and water intake. Groups B and C had lower water intake from beverages. Copyright © 2018 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

  2. Sex in an uncertain world: environmental stochasticity helps restore competitive balance between sexually and asexually reproducing populations.

    Science.gov (United States)

    Park, A W; Vandekerkhove, J; Michalakis, Y

    2014-08-01

    Like many organisms, individuals of the freshwater ostracod species Eucypris virens exhibit either obligate sexual or asexual reproductive modes. Both types of individual routinely co-occur, including in the same temporary freshwater pond (their natural habitat in which they undergo seasonal diapause). Given the well-known two-fold cost of sex, this begs the question of how sexually reproducing individuals are able to coexist with their asexual counterparts in spite of such overwhelming costs. Environmental stochasticity in the form of 'false dawn' inundations (where the first hydration is ephemeral and causes loss of early hatching individuals) may provide an advantage to the sexual subpopulation, which shows greater variation in hatching times following inundation. We explore the potential role of environmental stochasticity in this system using life-history data analysis, climate data, and matrix projection models. In the absence of environmental stochasticity, the population growth rate is significantly lower in sexual subpopulations. Climate data reveal that 'false dawn' inundations are common. Using matrix projection modelling with and without environmental stochasticity, we demonstrate that this phenomenon can restore appreciable balance to the system, in terms of population growth rates. This provides support for the role of environmental stochasticity in helping to explain the maintenance of sex and the occurrence of geographical parthenogenesis. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  3. Scale-invariance underlying the logistic equation and its social applications

    Energy Technology Data Exchange (ETDEWEB)

    Hernando, A., E-mail: alberto.hernando@irsamc.ups-tlse.fr [Laboratoire Collisions, Agrégats, Réactivité, IRSAMC, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 09 (France); Plastino, A., E-mail: plastino@fisica.unlp.edu.ar [National University La Plata, IFLP-CCT-CONICET, C.C. 727, 1900 La Plata (Argentina); Universitat de les Illes Balears and IFISC-CSIC, 07122 Palma de Mallorca (Spain)

    2013-01-03

    On the basis of dynamical principles we i) advance a derivation of the Logistic Equation (LE), widely employed (among multiple applications) in the simulation of population growth, and ii) demonstrate that scale-invariance and a mean-value constraint are sufficient and necessary conditions for obtaining it. We also generalize the LE to multi-component systems and show that the above dynamical mechanisms underlie a large number of scale-free processes. Examples are presented regarding city-populations, diffusion in complex networks, and popularity of technological products, all of them obeying the multi-component logistic equation in an either stochastic or deterministic way.

  4. Scale-invariance underlying the logistic equation and its social applications

    International Nuclear Information System (INIS)

    Hernando, A.; Plastino, A.

    2013-01-01

    On the basis of dynamical principles we i) advance a derivation of the Logistic Equation (LE), widely employed (among multiple applications) in the simulation of population growth, and ii) demonstrate that scale-invariance and a mean-value constraint are sufficient and necessary conditions for obtaining it. We also generalize the LE to multi-component systems and show that the above dynamical mechanisms underlie a large number of scale-free processes. Examples are presented regarding city-populations, diffusion in complex networks, and popularity of technological products, all of them obeying the multi-component logistic equation in an either stochastic or deterministic way.

  5. Dynamic Balance of Excitation and Inhibition in Human and Monkey Neocortex

    Science.gov (United States)

    Dehghani, Nima; Peyrache, Adrien; Telenczuk, Bartosz; Le van Quyen, Michel; Halgren, Eric; Cash, Sydney S.; Hatsopoulos, Nicholas G.; Destexhe, Alain

    2016-03-01

    Balance of excitation and inhibition is a fundamental feature of in vivo network activity and is important for its computations. However, its presence in the neocortex of higher mammals is not well established. We investigated the dynamics of excitation and inhibition using dense multielectrode recordings in humans and monkeys. We found that in all states of the wake-sleep cycle, excitatory and inhibitory ensembles are well balanced, and co-fluctuate with slight instantaneous deviations from perfect balance, mostly in slow-wave sleep. Remarkably, these correlated fluctuations are seen for many different temporal scales. The similarity of these computational features with a network model of self-generated balanced states suggests that such balanced activity is essentially generated by recurrent activity in the local network and is not due to external inputs. Finally, we find that this balance breaks down during seizures, where the temporal correlation of excitatory and inhibitory populations is disrupted. These results show that balanced activity is a feature of normal brain activity, and break down of the balance could be an important factor to define pathological states.

  6. Burnout and satisfaction with work-life balance among US physicians relative to the general US population.

    Science.gov (United States)

    Shanafelt, Tait D; Boone, Sonja; Tan, Litjen; Dyrbye, Lotte N; Sotile, Wayne; Satele, Daniel; West, Colin P; Sloan, Jeff; Oreskovich, Michael R

    2012-10-08

    Despite extensive data about physician burnout, to our knowledge, no national study has evaluated rates of burnout among US physicians, explored differences by specialty, or compared physicians with US workers in other fields. We conducted a national study of burnout in a large sample of US physicians from all specialty disciplines using the American Medical Association Physician Masterfile and surveyed a probability-based sample of the general US population for comparison. Burnout was measured using validated instruments. Satisfaction with work-life balance was explored. Of 27 276 physicians who received an invitation to participate, 7288 (26.7%) completed surveys. When assessed using the Maslach Burnout Inventory, 45.8% of physicians reported at least 1 symptom of burnout. Substantial differences in burnout were observed by specialty, with the highest rates among physicians at the front line of care access (family medicine, general internal medicine, and emergency medicine). Compared with a probability-based sample of 3442 working US adults, physicians were more likely to have symptoms of burnout (37.9% vs 27.8%) and to be dissatisfied with work-life balance (40.2% vs 23.2%) (P < .001 for both). Highest level of education completed also related to burnout in a pooled multivariate analysis adjusted for age, sex, relationship status, and hours worked per week. Compared with high school graduates, individuals with an MD or DO degree were at increased risk for burnout (odds ratio [OR], 1.36; P < .001), whereas individuals with a bachelor's degree (OR, 0.80; P = .048), master's degree (OR, 0.71; P = .01), or professional or doctoral degree other than an MD or DO degree (OR, 0.64; P = .04) were at lower risk for burnout. Burnout is more common among physicians than among other US workers. Physicians in specialties at the front line of care access seem to be at greatest risk.

  7. A balancing domain decomposition method by constraints for advection-diffusion problems

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Xuemin; Li, Jing

    2008-12-10

    The balancing domain decomposition methods by constraints are extended to solving nonsymmetric, positive definite linear systems resulting from the finite element discretization of advection-diffusion equations. A pre-conditioned GMRES iteration is used to solve a Schur complement system of equations for the subdomain interface variables. In the preconditioning step of each iteration, a partially sub-assembled finite element problem is solved. A convergence rate estimate for the GMRES iteration is established, under the condition that the diameters of subdomains are small enough. It is independent of the number of subdomains and grows only slowly with the subdomain problem size. Numerical experiments for several two-dimensional advection-diffusion problems illustrate the fast convergence of the proposed algorithm.

  8. High order well-balanced finite volume WENO schemes and discontinuous Galerkin methods for a class of hyperbolic systems with source terms

    International Nuclear Information System (INIS)

    Xing Yulong; Shu Chiwang

    2006-01-01

    Hyperbolic balance laws have steady state solutions in which the flux gradients are nonzero but are exactly balanced by the source term. In our earlier work [J. Comput. Phys. 208 (2005) 206-227; J. Sci. Comput., accepted], we designed a well-balanced finite difference weighted essentially non-oscillatory (WENO) scheme, which at the same time maintains genuine high order accuracy for general solutions, to a class of hyperbolic systems with separable source terms including the shallow water equations, the elastic wave equation, the hyperbolic model for a chemosensitive movement, the nozzle flow and a two phase flow model. In this paper, we generalize high order finite volume WENO schemes and Runge-Kutta discontinuous Galerkin (RKDG) finite element methods to the same class of hyperbolic systems to maintain a well-balanced property. Finite volume and discontinuous Galerkin finite element schemes are more flexible than finite difference schemes to treat complicated geometry and adaptivity. However, because of a different computational framework, the maintenance of the well-balanced property requires different technical approaches. After the description of our well-balanced high order finite volume WENO and RKDG schemes, we perform extensive one and two dimensional simulations to verify the properties of these schemes such as the exact preservation of the balance laws for certain steady state solutions, the non-oscillatory property for general solutions with discontinuities, and the genuine high order accuracy in smooth regions

  9. Methods of mathematical modelling continuous systems and differential equations

    CERN Document Server

    Witelski, Thomas

    2015-01-01

    This book presents mathematical modelling and the integrated process of formulating sets of equations to describe real-world problems. It describes methods for obtaining solutions of challenging differential equations stemming from problems in areas such as chemical reactions, population dynamics, mechanical systems, and fluid mechanics. Chapters 1 to 4 cover essential topics in ordinary differential equations, transport equations and the calculus of variations that are important for formulating models. Chapters 5 to 11 then develop more advanced techniques including similarity solutions, matched asymptotic expansions, multiple scale analysis, long-wave models, and fast/slow dynamical systems. Methods of Mathematical Modelling will be useful for advanced undergraduate or beginning graduate students in applied mathematics, engineering and other applied sciences.

  10. Electron-acoustic Instability Simulated By Modified Zakharov Equations

    Science.gov (United States)

    Jásenský, V.; Fiala, V.; Vána, O.; Trávnícek, P.; Hellinger, P.

    We present non-linear equations describing processes in plasma when electron - acoustic waves are excited. These waves are present for instance in the vicinity of Earth's bow shock and in the polar ionosphere. Frequently they are excited by an elec- tron beam in a plasma with two electron populations, a cold and hot one. We derive modified Zakharov equations from kinetic theory for such a case together with numer- ical method for solving of this type of equations. Bispectral analysis is used to show which non-linear wave processes are of importance in course of the instability. Finally, we compare these results with similar simulations using Vlasov approach.

  11. Nonlinear ordinary differential equations analytical approximation and numerical methods

    CERN Document Server

    Hermann, Martin

    2016-01-01

    The book discusses the solutions to nonlinear ordinary differential equations (ODEs) using analytical and numerical approximation methods. Recently, analytical approximation methods have been largely used in solving linear and nonlinear lower-order ODEs. It also discusses using these methods to solve some strong nonlinear ODEs. There are two chapters devoted to solving nonlinear ODEs using numerical methods, as in practice high-dimensional systems of nonlinear ODEs that cannot be solved by analytical approximate methods are common. Moreover, it studies analytical and numerical techniques for the treatment of parameter-depending ODEs. The book explains various methods for solving nonlinear-oscillator and structural-system problems, including the energy balance method, harmonic balance method, amplitude frequency formulation, variational iteration method, homotopy perturbation method, iteration perturbation method, homotopy analysis method, simple and multiple shooting method, and the nonlinear stabilized march...

  12. Mobility impairment, social engagement, and life satisfaction among the older population in China: a structural equation modeling analysis.

    Science.gov (United States)

    Li, Linna; Loo, Becky P Y

    2017-05-01

    Revealing the relationship between mobility impairment and life satisfaction can help to propose effective interventions to secure mobility and life satisfaction. However, the relationship remains unclear and lacks quantitative evidence in China. This study therefore assesses the association of mobility impairment, social engagement, and life satisfaction among the older population in China. Based on the sample of China Health and Retirement Longitudinal Survey database in 2013, a structural equation modeling is established. The sample size is 4245 with 55.9% with mobility impairment. The model shows that the length of suffering from disability is significantly related to mobility impairment (β = 0.058, p life satisfaction (β = -0.311, p life satisfaction (β = 0.211, p life satisfaction partly because they usually participate less in social activities. Different strategies are suggested to be adopted to improve the life satisfaction of the older population from the aspects of promoting mobility and social engagement, including improving the design of transport facilitates, providing assistive facilities for the seniors with severe mobility impairment, promoting the accessibility of community leisure and healthcare services, and constructing more community senior activity centers.

  13. HESS Opinions: Linking Darcy's equation to the linear reservoir

    Science.gov (United States)

    Savenije, Hubert H. G.

    2018-03-01

    In groundwater hydrology, two simple linear equations exist describing the relation between groundwater flow and the gradient driving it: Darcy's equation and the linear reservoir. Both equations are empirical and straightforward, but work at different scales: Darcy's equation at the laboratory scale and the linear reservoir at the watershed scale. Although at first sight they appear similar, it is not trivial to upscale Darcy's equation to the watershed scale without detailed knowledge of the structure or shape of the underlying aquifers. This paper shows that these two equations, combined by the water balance, are indeed identical provided there is equal resistance in space for water entering the subsurface network. This implies that groundwater systems make use of an efficient drainage network, a mostly invisible pattern that has evolved over geological timescales. This drainage network provides equally distributed resistance for water to access the system, connecting the active groundwater body to the stream, much like a leaf is organized to provide all stomata access to moisture at equal resistance. As a result, the timescale of the linear reservoir appears to be inversely proportional to Darcy's conductance, the proportionality being the product of the porosity and the resistance to entering the drainage network. The main question remaining is which physical law lies behind pattern formation in groundwater systems, evolving in a way that resistance to drainage is constant in space. But that is a fundamental question that is equally relevant for understanding the hydraulic properties of leaf veins in plants or of blood veins in animals.

  14. Balance Training Enhances Motor Coordination During a Perturbed Sidestep Cutting Task.

    Science.gov (United States)

    Oliveira, Anderson Souza; Silva, Priscila Brito; Lund, Morten Enemark; Farina, Dario; Kersting, Uwe Gustav

    2017-11-01

    Study Design Controlled laboratory study. Background Balance training may improve motor coordination. However, little is known about the changes in motor coordination during unexpected perturbations to postural control following balance training. Objectives To study the effects of balance training on motor coordination and knee mechanics during perturbed sidestep cutting maneuvers in healthy adults. Methods Twenty-six healthy men were randomly assigned to a training group or a control group. Before balance training, subjects performed unperturbed, 90° sidestep cutting maneuvers and 1 unexpected perturbed cut (10-cm translation of a movable platform). Participants in the training group participated in a 6-week balance training program, while those in the control group followed their regular activity schedule. Both groups were retested after a 6-week period. Surface electromyography was recorded from 16 muscles of the supporting limb and trunk, as well as kinematics and ground reaction forces. Motor modules were extracted from electromyography by nonnegative matrix factorization. External knee abduction moments were calculated using inverse dynamics equations. Results Balance training reduced the external knee abduction moment (33% ± 25%, PBalance training also increased burst duration for the motor module related to landing early in the perturbation phase (23% ± 11%, PBalance training resulted in altered motor coordination and a reduction in knee abduction moment during an unexpected perturbation. The previously reported reduction in injury incidence following balance training may be linked to changes in dynamic postural stability and modular neuromuscular control. J Orthop Sports Phys Ther 2017;47(11):853-862. Epub 23 Sep 2017. doi:10.2519/jospt.2017.6980.

  15. Effects of balance training using a virtual-reality system in older fallers

    Directory of Open Access Journals (Sweden)

    Duque G

    2013-02-01

    Full Text Available Gustavo Duque,1,2 Derek Boersma,1 Griselda Loza-Diaz,2 Sanobar Hassan,1 Hamlet Suarez,3 Dario Geisinger,3 Pushpa Suriyaarachchi,1 Anita Sharma,1 Oddom Demontiero1,21Falls and Fractures Clinic, Department of Geriatric Medicine, Nepean Hospital, Penrith, NSW, Australia; 2Ageing Bone Research Program, Division of Geriatric Medicine, Sydney Medical School Nepean, The University of Sydney, Penrith, NSW, Australia; 3British Hospital, CLAEH School of Medicine, Montevideo, UruguayAbstract: Poor balance is considered a challenging risk factor for falls in older adults. Therefore, innovative interventions for balance improvement in this population are greatly needed. The aim of this study was to evaluate the effect of a new virtual-reality system (the Balance Rehabilitation Unit [BRU] on balance, falls, and fear of falling in a population of community-dwelling older subjects with a known history of falls. In this study, 60 community-dwelling older subjects were recruited after being diagnosed with poor balance at the Falls and Fractures Clinic, Nepean Hospital (Penrith, NSW, Australia. Subjects were randomly assigned to either the BRU-training or control groups. Both groups received the usual falls prevention care. The BRU-training group attended balance training (two sessions/week for 6 weeks using an established protocol. Change in balance parameters was assessed in the BRU-training group at the end of their 6-week training program. Both groups were assessed 9 months after their initial assessment (month 0. Adherence to the BRU-training program was 97%. Balance parameters were significantly improved in the BRU-training group (P < 0.01. This effect was also associated with a significant reduction in falls and lower levels of fear of falling (P < 0.01. Some components of balance that were improved by BRU training showed a decline after 9 months post-training. In conclusion, BRU training is an effective and well-accepted intervention to improve balance

  16. The effect of subdivision on variation at multi-allelic loci under balancing selection

    DEFF Research Database (Denmark)

    Schierup, M H; Vekemans, X; Charlesworth, D

    2000-01-01

    Simulations are used to investigate the expected pattern of variation at loci under different forms of multi-allelic balancing selection in a finite island model of a subdivided population. The objective is to evaluate the effect of restricted migration among demes on the distribution of polymorp......Simulations are used to investigate the expected pattern of variation at loci under different forms of multi-allelic balancing selection in a finite island model of a subdivided population. The objective is to evaluate the effect of restricted migration among demes on the distribution...

  17. Balancing the dynamic Stark shift in a driven Jaynes-Cummings system

    International Nuclear Information System (INIS)

    Mogilevtsev, D; Kilin, S

    2004-01-01

    In this work we discuss the possibility of balancing a dynamic Shark shift in a Jaynes-Cummings system by simultaneously driving the cavity and the atom with classical fields, of the same frequency. For a lossless Jaynes-Cummings system this can lead to unusual atomic population dynamics. For a lossy Jaynes-Cummings system such balancing can lead to complete suppression of resonance fluorescence even for leaky cavities

  18. Development and sensitivity analysis of impact assessment equations based on stock-recruitment theory

    International Nuclear Information System (INIS)

    Savidge, I.R.; Gladden, J.B.; Campbell, K.P.; Ziesenis, J.S.

    1988-01-01

    A central and unresolved problem in assessing the impact of power plant operations on Hudson River fish populations was the prediction of long-term population changes resulting from impingement and entrainment mortality. A series of equations was developed from the Ricker and Beverton-Holt stock-recruitment models to address this issue. It was assumed that compensation occurs during a brief period early in the life cycle rather than throughout the life cycle. Equations were developed for the added power plant-induced mortality occurring before or after compensation in each model. Mortality added after compensation resulted in larger estimates of population reduction than mortality added before compensation. The simple deterministic and more complex age-structured models provided identical predictions of long-term changes in population size in most cases. Similarly, the simple models predicted population changes that were nearly identical to the average age-structured model with variable survival except when levels of variation were quite high and the population modeled was semelparous. Advantages of the equations developed herein are their simplicity, generality, and minimal data requirements. The predictions of long-term population changes resulting from impingement and entrainment mortality were not attained. The magnitude and form of the compensatory responses of Hudson River fish populations remained undetermined, so that an agreement on this critical component of prediction models could not be reached. 33 refs., 4 figs., 2 tabs

  19. Modified method of simplest equation: Powerful tool for obtaining exact and approximate traveling-wave solutions of nonlinear PDEs

    Science.gov (United States)

    Vitanov, Nikolay K.

    2011-03-01

    We discuss the class of equations ∑i,j=0mAij(u){∂iu}/{∂ti}∂+∑k,l=0nBkl(u){∂ku}/{∂xk}∂=C(u) where Aij( u), Bkl( u) and C( u) are functions of u( x, t) as follows: (i) Aij, Bkl and C are polynomials of u; or (ii) Aij, Bkl and C can be reduced to polynomials of u by means of Taylor series for small values of u. For these two cases the above-mentioned class of equations consists of nonlinear PDEs with polynomial nonlinearities. We show that the modified method of simplest equation is powerful tool for obtaining exact traveling-wave solution of this class of equations. The balance equations for the sub-class of traveling-wave solutions of the investigated class of equations are obtained. We illustrate the method by obtaining exact traveling-wave solutions (i) of the Swift-Hohenberg equation and (ii) of the generalized Rayleigh equation for the cases when the extended tanh-equation or the equations of Bernoulli and Riccati are used as simplest equations.

  20. Dirac Mass Dynamics in Multidimensional Nonlocal Parabolic Equations

    KAUST Repository

    Lorz, Alexander

    2011-01-17

    Nonlocal Lotka-Volterra models have the property that solutions concentrate as Dirac masses in the limit of small diffusion. Is it possible to describe the dynamics of the limiting concentration points and of the weights of the Dirac masses? What is the long time asymptotics of these Dirac masses? Can several Dirac masses coexist? We will explain how these questions relate to the so-called "constrained Hamilton-Jacobi equation" and how a form of canonical equation can be established. This equation has been established assuming smoothness. Here we build a framework where smooth solutions exist and thus the full theory can be developed rigorously. We also show that our form of canonical equation comes with a kind of Lyapunov functional. Numerical simulations show that the trajectories can exhibit unexpected dynamics well explained by this equation. Our motivation comes from population adaptive evolution a branch of mathematical ecology which models Darwinian evolution. © Taylor & Francis Group, LLC.

  1. Mean field theory for a balanced hypercolumn model of orientation selectivity in primary visual cortex

    DEFF Research Database (Denmark)

    Lerchner, Alexander; Sterner, G.; Hertz, J.

    2006-01-01

    We present a complete mean field theory for a balanced state of a simple model of an orientation hypercolumn, with a numerical procedure for solving the mean-field equations quantitatively. With our treatment, one can determine self-consistently both the firing rates and the firing correlations...

  2. A systematic review of balance and fall risk assessments with mobile phone technology.

    Science.gov (United States)

    Roeing, Kathleen L; Hsieh, Katherine L; Sosnoff, Jacob J

    2017-11-01

    Falls are a major health concern for older adults. Preventative measures can help reduce the incidence and severity of falls. Methods for assessing balance and fall risk factors are necessary to effectively implement preventative measures. Research groups are currently developing mobile applications to enable seniors, caregivers, and clinicians to monitor balance and fall risk. The following systematic review assesses the current state of mobile health apps for testing balance as a fall risk factor. Thirteen studies were identified and included in the review and analyzed based on study design, population, sample size, measures of balance, main outcome measures, and evaluation of validity and reliability. All studies successfully tested their applications, but only 38% evaluated the validity, and 23% evaluated the reliability of their applications. Of those, all applications were found to accurately and reliably measure balance on select variables. Four of the 13 studies included special populations groups. Out of the 13 studies, 12 reported clinicians as their intended user and seven reported seniors as their intended user. Further research should examine the validity of mobile health applications as well as report on the application's usability. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Influence of birthweight on childhood balance: Evidence from two British birth cohorts.

    Science.gov (United States)

    Okuda, Paola Matiko Martins; Swardfager, Walter; Ploubidis, George B; Pangelinan, Melissa; Cogo-Moreira, Hugo

    2018-01-26

    Birthweight is an important predictor of various fundamental aspects of childhood health and development. To examine the impact of birthweight on childhood balance performance classification and verify if this is replicable and consistent in different populations. Prospective birth cohort study. To describe heterogeneity in balance skills, latent class analyses were conducted separately with data from the 1958 National Child Development Study - NCDS (n = 12,778), and the 1970 British Cohort Study - BCS (n = 12,115). Four balance tasks for NCDS and five balance tasks for BCS. Birthweight was assessed as a predictor of balance skills. In both cohorts, two latent classes (good and poor balance skills) were identified. In both cohorts, higher birthweight was associated with a higher likelihood of having good balance skills. Boys were less likely to have good balance compared to girls. The results establish the reproducibility and consistency of the effect of birthweight on balance skills and point to early intervention for individuals with lower birthweight to mitigate the impact of motor impairment. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. 3-D Force-balanced Magnetospheric Configurations

    International Nuclear Information System (INIS)

    Sorin Zaharia; Cheng, C.Z.; Maezawa, K.

    2003-01-01

    The knowledge of plasma pressure is essential for many physics applications in the magnetosphere, such as computing magnetospheric currents and deriving magnetosphere-ionosphere coupling. A thorough knowledge of the 3-D pressure distribution has however eluded the community, as most in-situ pressure observations are either in the ionosphere or the equatorial region of the magnetosphere. With the assumption of pressure isotropy there have been attempts to obtain the pressure at different locations by either (a) mapping observed data (e.g., in the ionosphere) along the field lines of an empirical magnetospheric field model or (b) computing a pressure profile in the equatorial plane (in 2-D) or along the Sun-Earth axis (in 1-D) that is in force balance with the magnetic stresses of an empirical model. However, the pressure distributions obtained through these methods are not in force balance with the empirical magnetic field at all locations. In order to find a global 3-D plasma pressure distribution in force balance with the magnetospheric magnetic field, we have developed the MAG-3D code, that solves the 3-D force balance equation J x B = (upside-down delta) P computationally. Our calculation is performed in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials as B = (upside-down delta) psi x (upside-down delta) alpha. The pressure distribution, P = P(psi,alpha), is prescribed in the equatorial plane and is based on satellite measurements. In addition, computational boundary conditions for y surfaces are imposed using empirical field models. Our results provide 3-D distributions of magnetic field and plasma pressure as well as parallel and transverse currents for both quiet-time and disturbed magnetospheric conditions

  5. Comprehensive, blinded assessment of balance in orthostatic tremor.

    Science.gov (United States)

    Bhatti, Danish; Thompson, Rebecca; Xia, Yiwen; Hellman, Amy; Schmaderer, Lorene; Suing, Katie; McKune, Jennifer; Penke, Cynthia; Iske, Regan; Roeder, Bobbi Jo; Siu, Ka-Chun; Bertoni, John M; Torres-Russotto, Diego

    2018-02-01

    Orthostatic Tremor (OT) is a movement disorder characterized by a sensation of unsteadiness and tremors in the 13-18 Hz range present upon standing. The pathophysiology of OT is not well understood but there is a relationship between the sensation of instability and leg tremors. Despite the sensation of unsteadiness, OT patients do not fall often and balance in OT has not been formally assessed. We present a prospective blinded study comparing balance assessment in patients with OT versus healthy controls. We prospectively enrolled 34 surface Electromyography (EMG)-confirmed primary OT subjects and 21 healthy controls. Participants underwent evaluations of balance by blinded physical therapists (PT) with standardized, validated, commonly used balance scales and tasks. OT subjects were mostly female (30/34, 88%) and controls were majority males (13/20, 65%). The average age of OT subjects was 68.5 years (range 54-87) and for controls was 69.4 (range 32-86). The average duration of OT symptoms was 18 years. OT subjects did significantly worse on all the balance scales and on most balance tasks including Berg Balance Scale, Functional Gait Assessment, Dynamic Gait Index, Unipedal Stance Test, Functional Reach Test and pull test. Gait speed and five times sit to stand were normal in OT. Common validated balance scales are significantly abnormal in primary OT. Despite the objective finding of impaired balance, OT patients do not commonly have falls. The reported sensation of unsteadiness in this patient population seems to be out of proportion to the number of actual falls. Further studies are needed to determine which components of commonly used balance scales are affected by a sensation of unsteadiness and fear of falling. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. A Wii Bit of Fun: A Novel Platform to Deliver Effective Balance Training to Older Adults

    Science.gov (United States)

    Merriman, Niamh A.; Young, William R.; Newell, Fiona N.; Craig, Cathy

    2015-01-01

    Abstract Background: Falls and fall-related injuries are symptomatic of an aging population. This study aimed to design, develop, and deliver a novel method of balance training, using an interactive game-based system to promote engagement, with the inclusion of older adults at both high and low risk of experiencing a fall. Study Design: Eighty-two older adults (65 years of age and older) were recruited from sheltered accommodation and local activity groups. Forty volunteers were randomly selected and received 5 weeks of balance game training (5 males, 35 females; mean, 77.18 ± 6.59 years), whereas the remaining control participants recorded levels of physical activity (20 males, 22 females; mean, 76.62 ± 7.28 years). The effect of balance game training was measured on levels of functional balance and balance confidence in individuals with and without quantifiable balance impairments. Results: Balance game training had a significant effect on levels of functional balance and balance confidence (P risk of falls. The overall pattern of results suggests the training program is effective and suitable for individuals at all levels of ability and may therefore play a role in reducing the risk of falls. Conclusions: Commercial hardware can be modified to deliver engaging methods of effective balance assessment and training for the older population. PMID:26469308

  7. Population, internal migration, and economic growth: an empirical analysis.

    Science.gov (United States)

    Moreland, R S

    1982-01-01

    The role of population growth in the development process has received increasing attention during the last 15 years, as manifested in the literature in 3 broad categories. In the 1st category, the effects of rapid population growth on the growth of income have been studied with the use of simulation models, which sometimes include endogenous population growth. The 2nd category of the literature is concerned with theoretical and empirical studies of the economic determinants of various demographic rates--most usually fertility. Internal migration and dualism is the 3rd population development category to recieve attention. An attempt is made to synthesize developments in these 3 categories by estimating from a consistent set of data a 2 sector economic demographic model in which the major demographic rates are endogenous. Due to the fact that the interactions between economic and demographic variables are nonlinear and complex, the indirect effects of changes in a particular variable may depend upon the balance of numerical coefficients. For this reason it was felt that the model should be empirically grounded. A brief overview of the model is provided, and the model is compared to some similar existing models. Estimation of the model's 9 behavior equations is discussed, followed by a "base run" simulation of a developing country "stereotype" and a report of a number of policy experiments. The relatively new field of economic determinants of demographic variables was drawn upon in estimating equations to endogenize demographic phenomena that are frequently left exogenous in simulation models. The fertility and labor force participation rate functions are fairly standard, but a step beyong existing literature was taken in the life expectancy and intersectorial migration equations. On the economic side, sectoral savings functions were estimated, and it was found that the marginal propensity to save is lower in agriculture than in nonagriculture. Testing to see the

  8. Origin, evolution, and population genetics of the selfish Segregation Distorter gene duplication in European and African populations of Drosophila melanogaster.

    Science.gov (United States)

    Brand, Cara L; Larracuente, Amanda M; Presgraves, Daven C

    2015-05-01

    Meiotic drive elements are a special class of evolutionarily "selfish genes" that subvert Mendelian segregation to gain preferential transmission at the expense of homologous loci. Many drive elements appear to be maintained in populations as stable polymorphisms, their equilibrium frequencies determined by the balance between drive (increasing frequency) and selection (decreasing frequency). Here we show that a classic, seemingly balanced, drive system is instead characterized by frequent evolutionary turnover giving rise to dynamic, rather than stable, equilibrium frequencies. The autosomal Segregation Distorter (SD) system of the fruit fly Drosophila melanogaster is a selfish coadapted meiotic drive gene complex in which the major driver corresponds to a partial duplication of the gene Ran-GTPase activating protein (RanGAP). SD chromosomes segregate at similar, low frequencies of 1-5% in natural populations worldwide, consistent with a balanced polymorphism. Surprisingly, our population genetic analyses reveal evidence for parallel, independent selective sweeps of different SD chromosomes in populations on different continents. These findings suggest that, rather than persisting at a single stable equilibrium, SD chromosomes turn over frequently within populations. © 2015 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  9. Typical balance exercises or exergames for balance improvement?

    Science.gov (United States)

    Gioftsidou, Asimenia; Vernadakis, Nikolaos; Malliou, Paraskevi; Batzios, Stavros; Sofokleous, Polina; Antoniou, Panagiotis; Kouli, Olga; Tsapralis, Kyriakos; Godolias, George

    2013-01-01

    Balance training is an effective intervention to improve static postural sway and balance. The purpose of the present study was to investigate the effectiveness of the Nintendo Wii Fit Plus exercises for improving balance ability in healthy collegiate students in comparison with a typical balance training program. Forty students were randomly divided into two groups, a traditional (T group) and a Nintendo Wii group (W group) performed an 8 week balance program. The "W group" used the interactive games as a training method, while the "T group" used an exercise program with mini trampoline and inflatable discs (BOSU). Pre and Post-training participants completed balance assessments. Two-way repeated measures analyses of variance (ANOVAs) were conducted to determine the effect of training program. Analysis of the data illustrated that both training program groups demonstrated an improvement in Total, Anterior-posterior and Medial Lateral Stability Index scores for both limbs. Only at the test performed in the balance board with anterior-posterior motion, the improvement in balance ability was greater in the "T group" than the "W group", when the assessment was performed post-training (p=0.023). Findings support the effectiveness of using the Nintendo Wii gaming console as a balance training intervention tool.

  10. Comparison of dynamic balance ability in healthy university students according to foot shape.

    Science.gov (United States)

    Hyong, In Hyouk; Kang, Jong Ho

    2016-01-01

    [Purpose] This study aimed to compare dynamic balance ability according to foot shape, defined as normal, pronated, or supinated on the basis of the height of the medial arch. [Subjects] In this study, 14 subjects for the pronated foot group, 14 for the supinated foot group, and 14 for the normal foot group were selected from among 162 healthy university students by using the navicular drop test proposed by Brody. To measure dynamic balance ability, a star excursion balance test (SEBT) was conducted for each group, in which a cross-shaped line and lines at 45° in eight directions were drawn on the floor. In this study, only three directions were used, namely anterior, posterolateral, and posteromedial. The mean of the SEBT was calculated by measuring three times for each group, and the values were standardized using the following equation: measured value/leg length × 100. [Results] No significant differences in dynamic balance ability were found between the normal, pronated, and supinated foot groups. [Conclusion] No significant differences in dynamic balance ability according to the foot shape were found among the healthy university students with normal, pronated, and supinated feet.

  11. Dirac Mass Dynamics in Multidimensional Nonlocal Parabolic Equations

    KAUST Repository

    Lorz, Alexander; Mirrahimi, Sepideh; Perthame, Benoî t

    2011-01-01

    simulations show that the trajectories can exhibit unexpected dynamics well explained by this equation. Our motivation comes from population adaptive evolution a branch of mathematical ecology which models Darwinian evolution. © Taylor & Francis Group, LLC.

  12. Restricted magnetically balanced basis applied for relativistic calculations of indirect nuclear spin-spin coupling tensors in the matrix Dirac-Kohn-Sham framework

    International Nuclear Information System (INIS)

    Repisky, Michal; Komorovsky, Stanislav; Malkina, Olga L.; Malkin, Vladimir G.

    2009-01-01

    The relativistic four-component density functional approach based on the use of restricted magnetically balanced basis (mDKS-RMB), applied recently for calculations of NMR shielding, was extended for calculations of NMR indirect nuclear spin-spin coupling constants. The unperturbed equations are solved with the use of a restricted kinetically balanced basis set for the small component while to solve the second-order coupled perturbed DKS equations a restricted magnetically balanced basis set for the small component was applied. Benchmark relativistic calculations have been carried out for the X-H and H-H spin-spin coupling constants in the XH 4 series (X = C, Si, Ge, Sn and Pb). The method provides an attractive alternative to existing approximate two-component methods with transformed Hamiltonians for relativistic calculations of spin-spin coupling constants of heavy-atom systems. In particular, no picture-change effects arise in our method for property calculations

  13. A Review of Balance and Gait Capacities in Relation to Falls in Persons with Intellectual Disability

    Science.gov (United States)

    Enkelaar, Lotte; Smulders, Ellen; van Schrojenstein Lantman-de Valk, Henny; Geurts, Alexander C. H.; Weerdesteyn, Vivian

    2012-01-01

    Limitations in mobility are common in persons with intellectual disabilities (ID). As balance and gait capacities are key aspects of mobility, the prevalence of balance and gait problems is also expected to be high in this population. The objective of this study was to critically review the available literature on balance and gait characteristics…

  14. Balancing dual roles in end-of-life research.

    Science.gov (United States)

    Martin, Wanda; Grey, Meredith; Webber, Terry; Robinson, Linnea; Hartt, Nancy; Cairns, Moira; Stajduhar, Kelli

    2007-01-01

    Ethical and practical issues are sure to arise from the majority of research studies done with palliative populations. Whether it is feeling opportunistic, being emotionally available, or struggling with witnessing a gap in service and needs of the participants receiving care, nurses involved in research find a way to balance both roles to meet the needs of the participants as well as the study (McIlfatrick, Sullivan, & McKenna, 2006). This paper highlights some of the practical and ethical issues that arise when frontline nurses also take on the role of research assistant for studies with palliative populations. Specifically, the authors highlight their personal experiences based on their research assistant work on a study examining family caregiver coping in end-of-life cancer care. The authors discuss the "balancing act" of taking on these dual roles and offer recommendations on how to be with and approach people when doing research at the end of life using a framework based on Swanson's Theory of Caring (1991).

  15. Balancing of a rigid rotor using artificial neural network to predict the correction masses - DOI: 10.4025/actascitechnol.v31i2.3912

    Directory of Open Access Journals (Sweden)

    Fábio Lúcio Santos

    2009-06-01

    Full Text Available This paper deals with an analytical model of a rigid rotor supported by hydrodynamic journal bearings where the plane separation technique together with the Artificial Neural Network (ANN is used to predict the location and magnitude of the correction masses for balancing the rotor bearing system. The rotating system is modeled by applying the rigid shaft Stodola-Green model, in which the shaft gyroscopic moments and rotatory inertia are accounted for, in conjunction with the hydrodynamic cylindrical journal bearing model based on the classical Reynolds equation. A linearized perturbation procedure is employed to render the lubrication equations from the Reynolds equation, which allows predicting the eight linear force coefficients associated with the bearing direct and cross-coupled stiffness and damping coefficients. The results show that the methodology presented is efficient for balancing rotor systems. This paper gives a step further in the monitoring process, since Artificial Neural Network is normally used to predict, not to correct the mass unbalance. The procedure presented can be used in turbo machinery industry to balance rotating machinery that require continuous inspections. Some simulated results will be used in order to clarify the methodology presented.

  16. Horizon thermodynamics and gravitational field equations in Horava-Lifshitz gravity

    International Nuclear Information System (INIS)

    Cai Ronggen; Ohta, Nobuyoshi

    2010-01-01

    We explore the relationship between the first law of thermodynamics and gravitational field equation at a static, spherically symmetric black hole horizon in Horava-Lifshitz theory with/without detailed balance. It turns out that as in the cases of Einstein gravity and Lovelock gravity, the gravitational field equation can be cast to a form of the first law of thermodynamics at the black hole horizon. This way we obtain the expressions for entropy and mass in terms of black hole horizon, consistent with those from other approaches. We also define a generalized Misner-Sharp energy for static, spherically symmetric spacetimes in Horava-Lifshitz theory. The generalized Misner-Sharp energy is conserved in the case without matter field, and its variation gives the first law of black hole thermodynamics at the black hole horizon.

  17. Balance Problems

    Science.gov (United States)

    ... fully trust your sense of balance. Loss of balance also raises the risk of falls. This is a serious and even life-threatening ... 65. Balance disorders are serious because of the risk of falls. But occasionally balance problems may warn of another health condition, such ...

  18. Tests of stepping as indicators of mobility, balance, and fall risk in balance-impaired older adults.

    Science.gov (United States)

    Cho, Be-long; Scarpace, Diane; Alexander, Neil B

    2004-07-01

    To determine the relationships between two tests of stepping ability (the maximal step length (MSL) and rapid step test (RST)) and standard tests of standing balance, gait, mobility, and functional impairment in a group of at-risk older adults. Cross-sectional study. University-based laboratory. One hundred sixty-seven mildly balance-impaired older adults recruited for a balance-training and fall-reduction program (mean age 78, range 65-90). Measures of stepping maximally (MSL, the ability to maximally step out and return to the initial position) and rapidly (RST, the time taken to step out and return in multiple directions as fast as possible); standard measures of balance, gait, and mobility including timed tandem stance (TS), tandem walk (TW, both timing and errors), timed unipedal stance (US), timed up and go (TUG), performance oriented mobility assessment (POMA), and 6-minute walk (SMW); measures of leg strength (peak knee and ankle torque and power at slow and fast speeds); self-report measures of frequent falls (>2 per 12 months), disability (Established Population for Epidemiologic Studies of the Elderly (EPESE) physical function), and confidence to avoid falls (Activity-specific Balance Confidence (ABC) Scale). Spearman and Pearson correlation, intraclass correlation coefficient, logistic regression, and linear regression were used for data analysis. MSL consistently predicted a number of self-report and performance measures at least as well as other standard balance measures. MSL correlations with EPESE physical function, ABC, TUG, and POMA scores; SMW; and peak maximum knee and ankle torque and power were at least as high as those correlations seen with TS, TW, or US. MSL score was associated with the risk of being a frequent faller. In addition, the six MSL directions were highly correlated (up to 0.96), and any one of the leg directions yielded similar relationships with functional measures and a history of falls. Relationships between RST and these

  19. Attenuation compensation in least-squares reverse time migration using the visco-acoustic wave equation

    KAUST Repository

    Dutta, Gaurav

    2013-08-20

    Attenuation leads to distortion of amplitude and phase of seismic waves propagating inside the earth. Conventional acoustic and least-squares reverse time migration do not account for this distortion which leads to defocusing of migration images in highly attenuative geological environments. To account for this distortion, we propose to use the visco-acoustic wave equation for least-squares reverse time migration. Numerical tests on synthetic data show that least-squares reverse time migration with the visco-acoustic wave equation corrects for this distortion and produces images with better balanced amplitudes compared to the conventional approach. © 2013 SEG.

  20. FLRW Cosmology with Horava-Lifshitz Gravity: Impacts of Equations of State

    Science.gov (United States)

    Tawfik, A.; Abou El Dahab, E.

    2017-07-01

    Inspired by Lifshitz theory for quantum critical phenomena in condensed matter, Horava proposed a theory for quantum gravity with an anisotropic scaling in ultraviolet. In Horava-Lifshitz gravity (HLG), we have studied the impacts of six types of equations of state on the evolution of various cosmological parameters such as Hubble parameters and scale factor. From the comparison of the general relativity gravity with the HLG with detailed and without with non-detailed balance conditions, remarkable differences are found. Also, a noticeable dependence of singular and non-singular Big Bang on the equations of state is observed. We conclude that HLG explains various epochs in the early universe and might be able to reproduce the entire cosmic history with and without singular Big Bang.