Traveling wave front solutions in lateral-excitatory neuronal networks
Directory of Open Access Journals (Sweden)
Sittipong Ruktamatakul
2008-05-01
Full Text Available In this paper, we discuss the shape of traveling wave front solutions to a neuronal model with the connection function to be of lateral excitation type. This means that close connecting cells have an inhibitory influence, while cells that aremore distant have an excitatory influence. We give results on the shape of the wave fronts solutions, which exhibit different shapes depend ing on the size of a threshold parameter.
Travelling fronts in stochastic Stokes’ drifts
Blanchet, Adrien
2008-10-01
By analytical methods we study the large time properties of the solution of a simple one-dimensional model of stochastic Stokes\\' drift. Semi-explicit formulae allow us to characterize the behaviour of the solutions and compute global quantities such as the asymptotic speed of the center of mass or the effective diffusion coefficient. Using an equivalent tilted ratchet model, we observe that the speed of the center of mass converges exponentially to its limiting value. A diffuse, oscillating front attached to the center of mass appears. The description of the front is given using an asymptotic expansion. The asymptotic solution attracts all solutions at an algebraic rate which is determined by the effective diffusion coefficient. The proof relies on an entropy estimate based on homogenized logarithmic Sobolev inequalities. In the travelling frame, the macroscopic profile obeys to an isotropic diffusion. Compared with the original diffusion, diffusion is enhanced or reduced, depending on the regime. At least in the limit cases, the rate of convergence to the effective profile is always decreased. All these considerations allow us to define a notion of efficiency for coherent transport, characterized by a dimensionless number, which is illustrated on two simple examples of travelling potentials with a sinusoidal shape in the first case, and a sawtooth shape in the second case. © 2008 Elsevier B.V. All rights reserved.
Traveling wave fronts and the transition to saturation
International Nuclear Information System (INIS)
Munier, S.; Peschanski, R.
2004-01-01
We propose a general method to study the solutions to nonlinear QCD evolution equations, based on a deep analogy with the physics of traveling waves. In particular, we show that the transition to the saturation regime of high energy QCD is identical to the formation of the front of a traveling wave. Within this physical picture, we provide the expressions for the saturation scale and the gluon density profile as a function of the total rapidity and the transverse momentum. The application to the Balitskii-Kovchegov equation for both fixed and running coupling constants confirms the effectiveness of this method
Travelling fronts in stochastic Stokes’ drifts
Blanchet, Adrien; Dolbeault, Jean; Kowalczyk, Michał
2008-01-01
By analytical methods we study the large time properties of the solution of a simple one-dimensional model of stochastic Stokes' drift. Semi-explicit formulae allow us to characterize the behaviour of the solutions and compute global quantities
Pole solutions for flame front propagation
Kupervasser, Oleg
2015-01-01
This book deals with solving mathematically the unsteady flame propagation equations. New original mathematical methods for solving complex non-linear equations and investigating their properties are presented. Pole solutions for flame front propagation are developed. Premixed flames and filtration combustion have remarkable properties: the complex nonlinear integro-differential equations for these problems have exact analytical solutions described by the motion of poles in a complex plane. Instead of complex equations, a finite set of ordinary differential equations is applied. These solutions help to investigate analytically and numerically properties of the flame front propagation equations.
On the sharp front-type solution of the Nagumo equation with ...
Indian Academy of Sciences (India)
One of the methods is to solve the travelling wave equations and compute an exact solution which describes the sharp travelling wavefront. The second method is to solve numer- ically an initial-moving boundary-value problem for the partial differential equation and obtain an approximation for this sharp front-type solution.
Travelling wave solutions in delayed cooperative systems
International Nuclear Information System (INIS)
Li, Bingtuan; Zhang, Liang
2011-01-01
We establish the existence of travelling wave solutions for delayed cooperative recursions that are allowed to have more than two equilibria. We define an important extended real number that is used to determine the speeds of travelling wave solutions. The results can be applied to a large class of delayed cooperative reaction–diffusion models. We show that for a delayed Lotka–Volterra reaction–diffusion competition model, there exists a finite positive number c * + that can be characterized as the slowest speed of travelling wave solutions connecting two mono-culture equilibria or connecting a mono-culture with the coexistence equilibrium
A geometric classification of traveling front propagation in the Nagumo equation with cut-off
International Nuclear Information System (INIS)
Popovic, N
2011-01-01
An important category of solutions to reaction-diffusion systems of partial differential equations is given by traveling fronts, which provide a monotonic connection between rest states and maintain a fixed profile when considered in a co-moving frame. Reaction-diffusion equations are frequently employed in the mean-field (continuum) approximation of discrete (many-particle) models; however, the quality of this approximation deteriorates when the number of particles is not sufficiently large. The (stochastic) effects of this discreteness have been modeled via the introduction of (deterministic) 'cut-offs' that effectively deactivate the reaction terms at points where the particle concentration is below a certain threshold. In this article, we present an overview of the effects of such a cut-off on the front propagation dynamics in a prototypical reaction-diffusion system, the classical Nagumo equation. Our analysis is based on the method of geometric desingularization ('blow-up'), in combination with dynamical systems techniques such as invariant manifolds and normal forms. Using these techniques, we categorize front propagation in the cut-off Nagumo equation in dependence of a control parameter, and we classify the corresponding propagation regimes ('pulled,' 'pushed,' and 'bistable') in terms of the bifurcation structure of a projectivized system of equations that is obtained from the original traveling front problem, after blow-up. In particular, our approach allows us to determine rigorously the asymptotics (in the cut-off parameter) of the correction to the front propagation speed in the Nagumo equation that is due to a cut-off. Moreover, it explains the structure of that asymptotics (logarithmic, superlinear, or sublinear) in dependence of the front propagation regime. Finally, it enables us to calculate the corresponding leading-order coefficients in the resulting expansions in closed form.
EXACT TRAVELLING WAVE SOLUTIONS TO BBM EQUATION
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Abundant new travelling wave solutions to the BBM (Benjamin-Bona-Mahoni) equation are obtained by the generalized Jacobian elliptic function method. This method can be applied to other nonlinear evolution equations.
Traveling wave solution of the Reggeon field theory
International Nuclear Information System (INIS)
Peschanski, Robi
2009-01-01
We identify the nonlinear evolution equation in impact-parameter space for the 'Supercritical Pomeron' in Reggeon field theory as a two-dimensional stochastic Fisher-Kolmogorov-Petrovski-Piscounov equation. It exactly preserves unitarity and leads in its radial form to a high-energy traveling wave solution corresponding to a 'universal' behavior of the impact-parameter front profile of the elastic amplitude; its rapidity dependence and form depend only on one parameter, the noise strength, independently of the initial conditions and of the nonlinear terms restoring unitarity. Theoretical predictions are presented for the three typical distinct regimes corresponding to zero, weak, and strong noise.
International Nuclear Information System (INIS)
Wu Shiliang; Li Wantong
2009-01-01
This paper deals with the global asymptotic stability and uniqueness (up to translation) of bistable traveling fronts in a class of reaction-diffusion systems. The known results do not apply in solving these problems because the reaction terms do not satisfy the required monotone condition. To overcome the difficulty, a weak monotone condition is proposed for the reaction terms, which is called interval monotone condition. Under such a weak monotone condition, the existence and comparison theorem of solutions is first established for reaction-diffusion systems on R by appealing to the theory of abstract differential equations. The global asymptotic stability and uniqueness (up to translation) of bistable traveling fronts are then proved by the elementary super- and sub-solution comparison and squeezing methods for nonlinear evolution equations. Finally, these abstract results are applied to a two species competition-diffusion model and a system modeling man-environment-man epidemics.
Traveling wavefront solutions to nonlinear reaction-diffusion-convection equations
International Nuclear Information System (INIS)
Indekeu, Joseph O; Smets, Ruben
2017-01-01
Physically motivated modified Fisher equations are studied in which nonlinear convection and nonlinear diffusion is allowed for besides the usual growth and spread of a population. It is pointed out that in a large variety of cases separable functions in the form of exponentially decaying sharp wavefronts solve the differential equation exactly provided a co-moving point source or sink is active at the wavefront. The velocity dispersion and front steepness may differ from those of some previously studied exact smooth traveling wave solutions. For an extension of the reaction-diffusion-convection equation, featuring a memory effect in the form of a maturity delay for growth and spread, also smooth exact wavefront solutions are obtained. The stability of the solutions is verified analytically and numerically. (paper)
Traveling wavefront solutions to nonlinear reaction-diffusion-convection equations
Indekeu, Joseph O.; Smets, Ruben
2017-08-01
Physically motivated modified Fisher equations are studied in which nonlinear convection and nonlinear diffusion is allowed for besides the usual growth and spread of a population. It is pointed out that in a large variety of cases separable functions in the form of exponentially decaying sharp wavefronts solve the differential equation exactly provided a co-moving point source or sink is active at the wavefront. The velocity dispersion and front steepness may differ from those of some previously studied exact smooth traveling wave solutions. For an extension of the reaction-diffusion-convection equation, featuring a memory effect in the form of a maturity delay for growth and spread, also smooth exact wavefront solutions are obtained. The stability of the solutions is verified analytically and numerically.
New travelling wave solutions for nonlinear stochastic evolution ...
Indian Academy of Sciences (India)
expansion method to look for travelling wave solutions of nonlinear partial differential equations. It is interesting to mention that, in this method the sign of the parameters can be used to judge the numbers and types of travelling wave solutions.
Exact solutions to some nonlinear PDEs, travelling profiles method
Directory of Open Access Journals (Sweden)
Noureddine Benhamidouche
2008-04-01
\\end{equation*} by a new method that we call the travelling profiles method. This method allows us to find several forms of exact solutions including the classical forms such as travelling-wave and self-similar solutions.
New exact travelling wave solutions of nonlinear physical models
International Nuclear Information System (INIS)
Bekir, Ahmet; Cevikel, Adem C.
2009-01-01
In this work, we established abundant travelling wave solutions for some nonlinear evolution equations. This method was used to construct travelling wave solutions of nonlinear evolution equations. The travelling wave solutions are expressed by the hyperbolic functions, the trigonometric functions and the rational functions. The ((G ' )/G )-expansion method presents a wider applicability for handling nonlinear wave equations.
Traveling interface modulations and anisotropic front propagation in ammonia oxidation over Rh(110)
Energy Technology Data Exchange (ETDEWEB)
Rafti, Matías [Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Fac. Cs. Exactas, Universidad Nacional de La Plata, 64 y Diag. 113 (1900), La Plata (Argentina); Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstr. 3-3a, D-30167 Hannover (Germany); Borkenhagen, Benjamin; Lilienkamp, Gerhard [Institut für Energieforschung und Physikalische Technologien, Technische Universität Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld (Germany); Lovis, Florian; Smolinsky, Tim; Imbihl, Ronald, E-mail: imbihl@pci.uni-hannvover.de [Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstr. 3-3a, D-30167 Hannover (Germany)
2015-11-14
The bistable NH{sub 3} + O{sub 2} reaction over a Rh(110) surface was explored in the pressure range 10{sup −6}–10{sup −3} mbar and in the temperature range 300–900 K using photoemission electron microscopy and low energy electron microscopy as spatially resolving methods. We observed a history dependent anisotropy in front propagation, traveling interface modulations, transitions with secondary reaction fronts, and stationary island structures.
The classification of the single travelling wave solutions to the ...
Indian Academy of Sciences (India)
The discrimination system for the polynomial method is applied to variant Boussinesq equations to classify single travelling wave solutions. In particular, we construct corresponding solutions to the concrete parameters to show that each solution in the classification can be realized.
Traveling and Pinned Fronts in Bistable Reaction-Diffusion Systems on Networks
Kouvaris, Nikos E.; Kori, Hiroshi; Mikhailov, Alexander S.
2012-01-01
Traveling fronts and stationary localized patterns in bistable reaction-diffusion systems have been broadly studied for classical continuous media and regular lattices. Analogs of such non-equilibrium patterns are also possible in networks. Here, we consider traveling and stationary patterns in bistable one-component systems on random Erdös-Rényi, scale-free and hierarchical tree networks. As revealed through numerical simulations, traveling fronts exist in network-organized systems. They represent waves of transition from one stable state into another, spreading over the entire network. The fronts can furthermore be pinned, thus forming stationary structures. While pinning of fronts has previously been considered for chains of diffusively coupled bistable elements, the network architecture brings about significant differences. An important role is played by the degree (the number of connections) of a node. For regular trees with a fixed branching factor, the pinning conditions are analytically determined. For large Erdös-Rényi and scale-free networks, the mean-field theory for stationary patterns is constructed. PMID:23028746
Bifurcations and new exact travelling wave solutions for the ...
Indian Academy of Sciences (India)
By using the method of dynamical system, the bidirectional wave equations are considered. Based on this method, all kinds of phase portraits of the reduced travelling wave system in the parametric space are given. All possible bounded travelling wave solutions such as dark soliton solutions, bright soliton solutions and ...
Rippled shock front solutions for testing hydrodynamic stability simulations
International Nuclear Information System (INIS)
Munro, D.H.
1989-01-01
The response of a shock front to arbitrary small perturbations can be calculated analytically. Such rippled shock front solutions are useful for determining the accuracy of hydrodynamic simulation codes such as LASNEX [Comments Plasma Phys. Controlled Fusion 2, 51 (1977)], which are used to compute perturbation growth in inertial fusion targets. The LASNEX fractional errors are of order κ 2 L 2 , where κ is the transverse wavenumber of the perturbation, and L is the largest zone dimension. Numerical errors are about 25% for a calculation using 26 zones per transverse wavelength
expansion method and travelling wave solutions for the perturbed ...
Indian Academy of Sciences (India)
Abstract. In this paper, we construct the travelling wave solutions to the perturbed nonlinear. Schrödinger's equation (NLSE) with Kerr law non-linearity by the extended (G /G)-expansion method. Based on this method, we obtain abundant exact travelling wave solutions of NLSE with. Kerr law nonlinearity with arbitrary ...
Bifurcations and new exact travelling wave solutions for the ...
Indian Academy of Sciences (India)
2016-10-17
Oct 17, 2016 ... Abstract. By using the method of dynamical system, the bidirectional wave equations are considered. Based on this method, all kinds of phase portraits of the reduced travelling wave system in the parametric space are given. All possible bounded travelling wave solutions such as dark soliton solutions, ...
Bifurcation analysis and the travelling wave solutions of the Klein
Indian Academy of Sciences (India)
In this paper, we investigate the bifurcations and dynamic behaviour of travelling wave solutions of the Klein–Gordon–Zakharov equations given in Shang et al, Comput. Math. Appl. 56, 1441 (2008). Under different parameter conditions, we obtain some exact explicit parametric representations of travelling wave solutions by ...
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
Bifurcations of traveling wave solutions for an integrable equation
International Nuclear Information System (INIS)
Li Jibin; Qiao Zhijun
2010-01-01
This paper deals with the following equation m t =(1/2)(1/m k ) xxx -(1/2)(1/m k ) x , which is proposed by Z. J. Qiao [J. Math. Phys. 48, 082701 (2007)] and Qiao and Liu [Chaos, Solitons Fractals 41, 587 (2009)]. By adopting the phase analysis method of planar dynamical systems and the theory of the singular traveling wave systems to the traveling wave solutions of the equation, it is shown that for different k, the equation may have infinitely many solitary wave solutions, periodic wave solutions, kink/antikink wave solutions, cusped solitary wave solutions, and breaking loop solutions. We discuss in a detail the cases of k=-2,-(1/2),(1/2),2, and parametric representations of all possible bounded traveling wave solutions are given in the different (c,g)-parameter regions.
Traveling wave solutions for reaction-diffusion systems
DEFF Research Database (Denmark)
Lin, Zhigui; Pedersen, Michael; Tian, Canrong
2010-01-01
This paper is concerned with traveling waves of reaction–diffusion systems. The definition of coupled quasi-upper and quasi-lower solutions is introduced for systems with mixed quasimonotone functions, and the definition of ordered quasi-upper and quasi-lower solutions is also given for systems...... with quasimonotone nondecreasing functions. By the monotone iteration method, it is shown that if the system has a pair of coupled quasi-upper and quasi-lower solutions, then there exists at least a traveling wave solution. Moreover, if the system has a pair of ordered quasi-upper and quasi-lower solutions...
New exact travelling wave solutions of bidirectional wave equations
Indian Academy of Sciences (India)
Department of Mathematics, Sungkyunkwan University, Suwon 440-746, Republic of Korea. ∗ ... exact travelling wave solutions of system (1) using the modified tanh–coth function method ... The ordinary differential equation is then integrated.
A generic travelling wave solution in dissipative laser cavity
Indian Academy of Sciences (India)
2016-09-09
Sep 9, 2016 ... Abstract. A large family of cosh-Gaussian travelling wave solution of a complex Ginzburg–Landau equation ... pling, wherein the real part represents diffusive coupling ... knowledge, this is the first time that cosh-Gaussian pro-.
Symbolic computation and abundant travelling wave solutions to ...
Indian Academy of Sciences (India)
The method is reliable and useful, and gives more general exact travelling wave solutions than the existing methods. The solutions obtained are in the form of hyperbolic, trigonometricand rational functions including solitary, singular and periodic solutions which have many potential applications in physical science and ...
International Nuclear Information System (INIS)
Tang Xiaoyan; Shukla, Padma Kant
2008-01-01
Exact solutions, including the periodic travelling and non-travelling wave solutions, are presented for the nonlinear Klein-Gordon equation with imaginary mass. Some arbitrary functions are permitted in the periodic non-travelling wave solutions, which contribute to various high dimensional nonlinear structures
Travelling wave solutions to nonlinear physical models by means
Indian Academy of Sciences (India)
This paper presents the ﬁrst integral method to carry out the integration of nonlinear partial differential equations in terms of travelling wave solutions. For illustration, three important equations of mathematical physics are analytically investigated. Through the established ﬁrst integrals, exact solutions are successfully ...
Travelling wave solutions to the perturbed Π4 equation
International Nuclear Information System (INIS)
Geicke, J.
1985-01-01
Exact travelling wave solutions to the Π 4 equation, perturbed by a dissipative force and a constant external field η, are presented. For |η| 3 -λ 2 and λ 2 -λ 1 where λ 1 2 3 are the real roots of λ 3 -λ+η=O. The class with |v/ 3 -λ 1 . The stability of the solutions is discussed. (author) [pt
Travelling Wave Solutions to Stretched Beam's Equation: Phase Portraits Survey
International Nuclear Information System (INIS)
Betchewe, Gambo; Victor, Kuetche Kamgang; Thomas, Bouetou Bouetou; Kofane, Timoleon Crepin
2011-01-01
In this paper, following the phase portraits analysis, we investigate the integrability of a system which physically describes the transverse oscillation of an elastic beam under end-thrust. As a result, we find that this system actually comprises two families of travelling waves: the sub- and super-sonic periodic waves of positive- and negative-definite velocities, respectively, and the localized sub-sonic loop-shaped waves of positive-definite velocity. Expressing the energy-like of this system while depicting its phase portrait dynamics, we show that these multivalued localized travelling waves appear as the boundary solutions to which the periodic travelling waves tend asymptotically. (general)
The classification of single travelling wave solutions to the Camassa ...
Indian Academy of Sciences (India)
Introduction. Classifications of single travelling wave solutions to some nonlinear differential equations have been obtained extensively by the complete discrimination system for polynomial method proposed by Liu [1–7]. Furthermore, Wang and Li [8] used Liu's method and factorization method proposed by Cornejo-Pérez ...
The classification of the single travelling wave solutions to the ...
Indian Academy of Sciences (India)
a large number of methods for finding exact solutions have been established and devel ... Painleve method [1] and transformed rational function method for finding ... travelling wave transformation and integrating it, the nonlinear differential ...... The project is supported by Scientific Research Fund of Education Department of.
The classification of the single travelling wave solutions to the ...
Indian Academy of Sciences (India)
2016-09-21
Sep 21, 2016 ... For example,. Fan used Liu's method [11,12] to invest the generalized equal width equation and Pochhammer–Chree equa- tion, and she obtained all the possible travelling wave solutions including elliptic functions and hyperelliptic functions. In this paper, we consider the variant Boussinesq equations [13].
Exact travelling wave solutions for some important nonlinear
Indian Academy of Sciences (India)
The two-dimensional nonlinear physical models and coupled nonlinear systems such as Maccari equations, Higgs equations and Schrödinger–KdV equations have been widely applied in many branches of physics. So, finding exact travelling wave solutions of such equations are very helpful in the theories and numerical ...
On The Travelling Wave Solution For An SEIR Epidemic Disease ...
African Journals Online (AJOL)
We present the travelling wave solution for a Susceptible, Exposed, Infective and Removed (SEIR) epidemic disease model. For this SEIR model, the disease is driven by both the latent and infective class (the diffusion term is included in both classes). The population is closed. Keywords: Epidemic model, spatial spread, ...
New travelling wave solutions for nonlinear stochastic evolution
Indian Academy of Sciences (India)
The nonlinear stochastic evolution equations have a wide range of applications in physics, chemistry, biology, economics and finance from various points of view. In this paper, the (′/)-expansion method is implemented for obtaining new travelling wave solutions of the nonlinear (2 + 1)-dimensional stochastic ...
Symbolic computation and abundant travelling wave solutions to ...
Indian Academy of Sciences (India)
2016-12-09
Dec 9, 2016 ... Abstract. In this article, the novel (G /G)-expansion method is successfully applied to construct the abundant travelling wave solutions to the KdV–mKdV equation with the aid of symbolic computation. This equation is one of the most popular equation in soliton physics and appear in many practical scenarios ...
Investigating The Travelling Wave Solution For an SIR Endemic ...
African Journals Online (AJOL)
This paper presents the travelling wave solution for an SIR endemic disease model with no disease related death when the spatial spread of the susceptible is not negligible. In this case the disease is driven by both the susceptible and the infective classes. The population is open since the disease is habitually prevalent in ...
Travelling wave solutions to the Kuramoto-Sivashinsky equation
International Nuclear Information System (INIS)
Nickel, J.
2007-01-01
Combining the approaches given by Baldwin [Baldwin D et al. Symbolic computation of exact solutions expressible in hyperbolic and elliptic functions for nonlinear PDEs. J Symbol Comput 2004;37:669-705], Peng [Peng YZ. A polynomial expansion method and new general solitary wave solutions to KS equation. Comm Theor Phys 2003;39:641-2] and by Schuermann [Schuermann HW, Serov VS. Weierstrass' solutions to certain nonlinear wave and evolution equations. Proc progress electromagnetics research symposium, 28-31 March 2004, Pisa. p. 651-4; Schuermann HW. Traveling-wave solutions to the cubic-quintic nonlinear Schroedinger equation. Phys Rev E 1996;54:4312-20] leads to a method for finding exact travelling wave solutions of nonlinear wave and evolution equations (NLWEE). The first idea is to generalize ansaetze given by Baldwin and Peng to find elliptic solutions of NLWEEs. Secondly, conditions used by Schuermann to find physical (real and bounded) solutions and to discriminate between periodic and solitary wave solutions are used. The method is shown in detail by evaluating new solutions of the Kuramoto-Sivashinsky equation
Traveling waves in a spatially-distributed Wilson-Cowan model of cortex: From fronts to pulses
Harris, Jeremy D.; Ermentrout, Bard
2018-04-01
Wave propagation in excitable media has been studied in various biological, chemical, and physical systems. Waves are among the most common evoked and spontaneous organized activity seen in cortical networks. In this paper, we study traveling fronts and pulses in a spatially-extended version of the Wilson-Cowan equations, a neural firing rate model of sensory cortex having two population types: Excitatory and inhibitory. We are primarily interested in the case when the local or space-clamped dynamics has three fixed points: (1) a stable down state; (2) a saddle point with stable manifold that acts as a threshold for firing; (3) an up state having stability that depends on the time scale of the inhibition. In the case when the up state is stable, we look for wave fronts, which transition the media from a down to up state, and when the up state is unstable, we are interested in pulses, a transient increase in firing that returns to the down state. We explore the behavior of these waves as the time and space scales of the inhibitory population vary. Some interesting findings include bistability between a traveling front and pulse, fronts that join the down state to an oscillation or spatiotemporal pattern, and pulses which go through an oscillatory instability.
Travelling Wave Solutions in Multigroup Age-Structured Epidemic Models
Ducrot, Arnaut; Magal, Pierre; Ruan, Shigui
2010-01-01
Age-structured epidemic models have been used to describe either the age of individuals or the age of infection of certain diseases and to determine how these characteristics affect the outcomes and consequences of epidemiological processes. Most results on age-structured epidemic models focus on the existence, uniqueness, and convergence to disease equilibria of solutions. In this paper we investigate the existence of travelling wave solutions in a deterministic age-structured model describing the circulation of a disease within a population of multigroups. Individuals of each group are able to move with a random walk which is modelled by the classical Fickian diffusion and are classified into two subclasses, susceptible and infective. A susceptible individual in a given group can be crisscross infected by direct contact with infective individuals of possibly any group. This process of transmission can depend upon the age of the disease of infected individuals. The goal of this paper is to provide sufficient conditions that ensure the existence of travelling wave solutions for the age-structured epidemic model. The case of two population groups is numerically investigated which applies to the crisscross transmission of feline immunodeficiency virus (FIV) and some sexual transmission diseases.
TRAVELING WAVE SOLUTIONS OF SOME FRACTIONAL DIFFERENTIAL EQUATIONS
Directory of Open Access Journals (Sweden)
SERIFE MUGE EGE
2016-07-01
Full Text Available The modified Kudryashov method is powerful, efficient and can be used as an alternative to establish new solutions of different type of fractional differential equations applied in mathematical physics. In this article, we’ve constructed new traveling wave solutions including symmetrical Fibonacci function solutions, hyperbolic function solutions and rational solutions of the space-time fractional Cahn Hillihard equation D_t^α u − γD_x^α u − 6u(D_x^α u^2 − (3u^2 − 1D_x^α (D_x^α u + D_x^α(D_x^α(D_x^α(D_x^α u = 0 and the space-time fractional symmetric regularized long wave (SRLW equation D_t^α(D_t^α u + D_x^α(D_x^α u + uD_t^α(D_x^α u + D_x^α u D_t^α u + D_t^α(D_t^α(D_x^α(D_x^α u = 0 via modified Kudryashov method. In addition, some of the solutions are described in the figures with the help of Mathematica.
Interferometric measurements of a dendritic growth front solutal diffusion layer
Hopkins, John A.; Mccay, T. D.; Mccay, Mary H.
1991-01-01
An experimental study was undertaken to measure solutal distributions in the diffusion layer produced during the vertical directional solidification (VDS) of an ammonium chloride - water (NH4Cl-H2O) solution. Interferometry was used to obtain concentration measurements in the 1-2 millimeter region defining the diffusion layer. These measurements were fitted to an exponential form to extract the characteristic diffusion parameter for various times after the start of solidification. The diffusion parameters are within the limits predicted by steady state theory and suggest that the effective solutal diffusivity is increasing as solidification progresses.
Travelling-wave amplitudes as solutions of the phase-field crystal equation
Nizovtseva, I. G.; Galenko, P. K.
2018-01-01
The dynamics of the diffuse interface between liquid and solid states is analysed. The diffuse interface is considered as an envelope of atomic density amplitudes as predicted by the phase-field crystal model (Elder et al. 2004 Phys. Rev. E 70, 051605 (doi:10.1103/PhysRevE.70.051605); Elder et al. 2007 Phys. Rev. B 75, 064107 (doi:10.1103/PhysRevB.75.064107)). The propagation of crystalline amplitudes into metastable liquid is described by the hyperbolic equation of an extended Allen-Cahn type (Galenko & Jou 2005 Phys. Rev. E 71, 046125 (doi:10.1103/PhysRevE.71.046125)) for which the complete set of analytical travelling-wave solutions is obtained by the method (Malfliet & Hereman 1996 Phys. Scr. 15, 563-568 (doi:10.1088/0031-8949/54/6/003); Wazwaz 2004 Appl. Math. Comput. 154, 713-723 (doi:10.1016/S0096-3003(03)00745-8)). The general solution of travelling waves is based on the function of hyperbolic tangent. Together with its set of particular solutions, the general solution is analysed within an example of specific task about the crystal front invading metastable liquid (Galenko et al. 2015 Phys. D 308, 1-10 (doi:10.1016/j.physd.2015.06.002)). The influence of the driving force on the phase-field profile, amplitude velocity and correlation length is investigated for various relaxation times of the gradient flow. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.
International Nuclear Information System (INIS)
Yang Zonghang
2007-01-01
We find new exact travelling wave solutions for two potential KdV equations which are presented by Foursov [Foursov MV. J Math Phys 2000;41:6173-85]. Compared with the extended tanh-function method, the algorithm used in our paper can obtain some new kinds of exact travelling wave solutions. With the aid of symbolic computation, some novel exact travelling wave solutions of the potential KdV equations are constructed
Absolute instabilities of travelling wave solutions in a Keller-Segel model
Davis, P. N.; van Heijster, P.; Marangell, R.
2016-01-01
We investigate the spectral stability of travelling wave solutions in a Keller-Segel model of bacterial chemotaxis with a logarithmic chemosensitivity function and a constant, sublinear, and linear consumption rate. Linearising around the travelling wave solutions, we locate the essential and absolute spectrum of the associated linear operators and find that all travelling wave solutions have essential spectrum in the right half plane. However, we show that in the case of constant or sublinea...
Space-time adaptive hp-FEM for problems with traveling sharp fronts
Czech Academy of Sciences Publication Activity Database
Šolín, Pavel; Korous, L.
2013-01-01
Roč. 95, č. 1 (2013), S709-S722 ISSN 0010-485X Institutional support: RVO:61388998 Keywords : adaptive hp-FEM * transient problems * sharp fronts Subject RIV: BA - General Mathematics Impact factor: 1.055, year: 2013
Islam, Md Hamidul; Khan, Kamruzzaman; Akbar, M Ali; Salam, Md Abdus
2014-01-01
Mathematical modeling of many physical systems leads to nonlinear evolution equations because most physical systems are inherently nonlinear in nature. The investigation of traveling wave solutions of nonlinear partial differential equations (NPDEs) plays a significant role in the study of nonlinear physical phenomena. In this article, we construct the traveling wave solutions of modified KDV-ZK equation and viscous Burgers equation by using an enhanced (G '/G) -expansion method. A number of traveling wave solutions in terms of unknown parameters are obtained. Derived traveling wave solutions exhibit solitary waves when special values are given to its unknown parameters. 35C07; 35C08; 35P99.
Evaluation of Front Morphological Development of Reactive Solute Transport Using Behavior Diagrams
Directory of Open Access Journals (Sweden)
Jui-Sheng Chen
2009-01-01
Full Text Available While flowing through porous medium, ground water flow dissolves minerals thereby in creasing medium porosity and ultimately permeability. Reactive fluid flows preferentially into highly permeable zones, which are therefore dissolved most rapidly, producing a further preferential permeability enhancement. Accordingly, slight non-uniformities present in porous medium can be amplified and lead to fingering reaction fronts. The objective of this study is to investigate dissolution-induced porosity changes on reaction front morphology in homogeneous porous medium with two non-uniformities. Four controlling parameters, including up stream pressure gradient, reaction rate constant, non-uniformities spacing and non-uniformity strength ratio are comprehensively considered. By using a modified version of the numerical code, NSPCRT, to conduct a series of numerical simulations, front behavior diagrams are constructed to illustrate the morphologies of reaction fronts under various combinations of these four factors. Simulation results indicate that the two non-uniformities are inhibited into a planar front under low up stream pressure gradient, merge into a single-fingering front under inter mediate up stream pressure gradient, or grow into a double-fingers front under high up stream pressure gradient. More over, the two non-uniformities tend to develop intoadouble-fingering front as the non-uniformity strength ratio in creases from 0.2 to 1.0, and merge into a single-fingering front while the non-uniformity strength ratio in creases from 1.0 to 1.8. When the reaction rate constant is small, the two non-uniformities merge into a single front. Reaction rate constant significantly affects front advancing velocity. The front advancing velocity decreases with the reaction rate constant. Based on these results, front behavior diagrams which de fine the morphologies of the reaction fronts for these four parameters are constructed. Moreover, non
Directory of Open Access Journals (Sweden)
M. Arshad
Full Text Available In this manuscript, we constructed different form of new exact solutions of generalized coupled Zakharov–Kuznetsov and dispersive long wave equations by utilizing the modified extended direct algebraic method. New exact traveling wave solutions for both equations are obtained in the form of soliton, periodic, bright, and dark solitary wave solutions. There are many applications of the present traveling wave solutions in physics and furthermore, a wide class of coupled nonlinear evolution equations can be solved by this method. Keywords: Traveling wave solutions, Elliptic solutions, Generalized coupled Zakharov–Kuznetsov equation, Dispersive long wave equation, Modified extended direct algebraic method
International Nuclear Information System (INIS)
Abdou, M.A.
2008-01-01
The generalized F-expansion method with a computerized symbolic computation is used for constructing a new exact travelling wave solutions for the generalized nonlinear Schrodinger equation with a source. As a result, many exact travelling wave solutions are obtained which include new periodic wave solution, trigonometric function solutions and rational solutions. The method is straightforward and concise, and it can also be applied to other nonlinear evolution equations in physics
Caglayan, Sibel
2017-01-01
The objective of this Thesis was to dive into the world of mobile travel booking in order to find out which kinds of mobile technologies travel booking applications might adopt in the future. Furthermore, to find out whether or not there are mobile solutions coming up that might challenge the existence of apps. Travel booking is a versatile industry with many different aspects to it, especially in mobile booking solutions. The research was conducted by using primary and secondary research met...
Traveling Wave Solutions of ZK-BBM Equation Sine-Cosine Method
Directory of Open Access Journals (Sweden)
Sadaf Bibi
2014-03-01
Full Text Available Travelling wave solutions are obtained by using a relatively new technique which is called sine-cosine method for ZK-BBM equations. Solution procedure and obtained results re-confirm the efficiency of the proposed scheme.
Travelling Solitary Wave Solutions for Generalized Time-delayed Burgers-Fisher Equation
International Nuclear Information System (INIS)
Deng Xijun; Han Libo; Li Xi
2009-01-01
In this paper, travelling wave solutions for the generalized time-delayed Burgers-Fisher equation are studied. By using the first-integral method, which is based on the ring theory of commutative algebra, we obtain a class of travelling solitary wave solutions for the generalized time-delayed Burgers-Fisher equation. A minor error in the previous article is clarified. (general)
Bifurcations of Exact Traveling Wave Solutions for (2+1)-Dimensional HNLS Equation
International Nuclear Information System (INIS)
Xu Yuanfen
2012-01-01
For the (2+1)-Dimensional HNLS equation, what are the dynamical behavior of its traveling wave solutions and how do they depend on the parameters of the systems? This paper will answer these questions by using the methods of dynamical systems. Ten exact explicit parametric representations of the traveling wave solutions are given. (general)
Travelling wave solutions of the generalized Benjamin-Bona-Mahony equation
International Nuclear Information System (INIS)
Estevez, P.G.; Kuru, S.; Negro, J.; Nieto, L.M.
2009-01-01
A class of particular travelling wave solutions of the generalized Benjamin-Bona-Mahony equation is studied systematically using the factorization technique. Then, the general travelling wave solutions of Benjamin-Bona-Mahony equation, and of its modified version, are also recovered.
Exact travelling wave solutions of the (3+1)-dimensional mKdV-ZK ...
Indian Academy of Sciences (India)
In this paper, the new generalized (′/)-expansion method is executed to find the travelling wave solutions of the (3+1)-dimensional mKdV-ZK equation and the (1+1)-dimensional compound KdVB equation. The efficiency of this method for finding exact and travelling wave solutions has been demonstrated. It is shown ...
Numerical study of traveling-wave solutions for the Camassa-Holm equation
International Nuclear Information System (INIS)
Kalisch, Henrik; Lenells, Jonatan
2005-01-01
We explore numerically different aspects of periodic traveling-wave solutions of the Camassa-Holm equation. In particular, the time evolution of some recently found new traveling-wave solutions and the interaction of peaked and cusped waves is studied
New Exact Travelling Wave and Periodic Solutions of Discrete Nonlinear Schroedinger Equation
International Nuclear Information System (INIS)
Yang Qin; Dai Chaoqing; Zhang Jiefang
2005-01-01
Some new exact travelling wave and period solutions of discrete nonlinear Schroedinger equation are found by using a hyperbolic tangent function approach, which was usually presented to find exact travelling wave solutions of certain nonlinear partial differential models. Now we can further extend the new algorithm to other nonlinear differential-different models.
A. Bouter (Anton); K. Pirpinia (Kleopatra); T. Alderliesten (Tanja); P.A.N. Bosman (Peter)
2017-01-01
textabstractA multi-objective optimization approach is o.en followed by an a posteriori decision-making process, during which the most appropriate solution of the Pareto set is selected by a professional in the .eld. Conventional visualization methods do not correct for Pareto fronts with
Online Learning Solutions for Freeway Travel Time Prediction
Van Lint, J.W.C.
2008-01-01
Providing travel time information to travelers on available route alternatives in traffic networks is widely believed to yield positive effects on individual drive behavior and (route/departure time) choice behavior, as well as on collective traffic operations in terms of, for example, overall time
Algebraic Traveling Wave Solutions of a Non-local Hydrodynamic-type Model
International Nuclear Information System (INIS)
Chen, Aiyong; Zhu, Wenjing; Qiao, Zhijun; Huang, Wentao
2014-01-01
In this paper we consider the algebraic traveling wave solutions of a non-local hydrodynamic-type model. It is shown that algebraic traveling wave solutions exist if and only if an associated first order ordinary differential system has invariant algebraic curve. The dynamical behavior of the associated ordinary differential system is analyzed. Phase portraits of the associated ordinary differential system is provided under various parameter conditions. Moreover, we classify algebraic traveling wave solutions of the model. Some explicit formulas of smooth solitary wave and cuspon solutions are obtained
The (′/-Expansion Method for Abundant Traveling Wave Solutions of Caudrey-Dodd-Gibbon Equation
Directory of Open Access Journals (Sweden)
Hasibun Naher
2011-01-01
Full Text Available We construct the traveling wave solutions of the fifth-order Caudrey-Dodd-Gibbon (CDG equation by the (/-expansion method. Abundant traveling wave solutions with arbitrary parameters are successfully obtained by this method and the wave solutions are expressed in terms of the hyperbolic, the trigonometric, and the rational functions. It is shown that the (/-expansion method is a powerful and concise mathematical tool for solving nonlinear partial differential equations.
Abundant families of new traveling wave solutions for the coupled Drinfel'd-Sokolov-Wilson equation
International Nuclear Information System (INIS)
Yao Yuqin
2005-01-01
The generalized Jacobi elliptic function method is further improved by introducing an elliptic function φ(ξ) as a new independent variable and it is easy to calculate the over-determined equations. Abundant new traveling wave solutions of the coupled Drinfel'd-Sokolov-Wilson equation are obtained. The solutions obtained include the kink-shaped solutions, bell-shaped solutions, singular solutions and periodic solutions
International Nuclear Information System (INIS)
Zhang Zaiyun; Liu Zhenhai; Miao Xiujin; Chen Yuezhong
2011-01-01
In this Letter, we investigate the perturbed nonlinear Schroedinger's equation (NLSE) with Kerr law nonlinearity. All explicit expressions of the bounded traveling wave solutions for the equation are obtained by using the bifurcation method and qualitative theory of dynamical systems. These solutions contain bell-shaped solitary wave solutions, kink-shaped solitary wave solutions and Jacobi elliptic function periodic solutions. Moreover, we point out the region which these periodic wave solutions lie in. We present the relation between the bounded traveling wave solution and the energy level h. We find that these periodic wave solutions tend to the corresponding solitary wave solutions as h increases or decreases. Finally, for some special selections of the energy level h, it is shown that the exact periodic solutions evolute into solitary wave solution.
New traveling wave solutions to AKNS and SKdV equations
International Nuclear Information System (INIS)
Ozer, Teoman
2009-01-01
We analyze the traveling wave solutions of Ablowitz-Kaup-Newell-Segur (AKNS) and Schwarz-Korteweg-de Vries (SKdV) equations. As the solution method for differential equations we consider the improved tanh approach. This approach provides to transform the partial differential equation into the ordinary differential equation and then obtain the new families of exact solutions based on the solutions of the Riccati equation. The different values of the coefficients of the Riccati equation allow us to obtain new type of traveling wave solutions to AKNS and SKdV equations.
Absolute instabilities of travelling wave solutions in a Keller-Segel model
Davis, P. N.; van Heijster, P.; Marangell, R.
2017-11-01
We investigate the spectral stability of travelling wave solutions in a Keller-Segel model of bacterial chemotaxis with a logarithmic chemosensitivity function and a constant, sublinear, and linear consumption rate. Linearising around the travelling wave solutions, we locate the essential and absolute spectrum of the associated linear operators and find that all travelling wave solutions have parts of the essential spectrum in the right half plane. However, we show that in the case of constant or sublinear consumption there exists a range of parameters such that the absolute spectrum is contained in the open left half plane and the essential spectrum can thus be weighted into the open left half plane. For the constant and sublinear consumption rate models we also determine critical parameter values for which the absolute spectrum crosses into the right half plane, indicating the onset of an absolute instability of the travelling wave solution. We observe that this crossing always occurs off of the real axis.
Exact Travelling Solutions of Discrete sine-Gordon Equation via Extended Tanh-Function Approach
International Nuclear Information System (INIS)
Dai Chaoqing; Zhang Jiefang
2006-01-01
In this paper, we generalize the extended tanh-function approach, which was used to find new exact travelling wave solutions of nonlinear partial differential equations or coupled nonlinear partial differential equations, to nonlinear differential-difference equations. As illustration, two series of exact travelling wave solutions of the discrete sine-Gordon equation are obtained by means of the extended tanh-function approach.
A new auxiliary equation and exact travelling wave solutions of nonlinear equations
International Nuclear Information System (INIS)
Sirendaoreji
2006-01-01
A new auxiliary ordinary differential equation and its solutions are used for constructing exact travelling wave solutions of nonlinear partial differential equations in a unified way. The main idea of this method is to take full advantage of the auxiliary equation which has more new exact solutions. More new exact travelling wave solutions are obtained for the quadratic nonlinear Klein-Gordon equation, the combined KdV and mKdV equation, the sine-Gordon equation and the Whitham-Broer-Kaup equations
Travelling wave solutions for some time-delayed equations through factorizations
International Nuclear Information System (INIS)
Fahmy, E.S.
2008-01-01
In this work, we use factorization method to find explicit particular travelling wave solutions for the following important nonlinear second-order partial differential equations: The generalized time-delayed Burgers-Huxley, time-delayed convective Fishers, and the generalized time-delayed Burgers-Fisher. Using the particular solutions for these equations we find the general solutions, two-parameter solution, as special cases
New exact travelling wave solutions for the Ostrovsky equation
International Nuclear Information System (INIS)
Kangalgil, Figen; Ayaz, Fatma
2008-01-01
In this Letter, auxiliary equation method is proposed for constructing more general exact solutions of nonlinear partial differential equation with the aid of symbolic computation. In order to illustrate the validity and the advantages of the method we choose the Ostrovsky equation. As a result, many new and more general exact solutions have been obtained for the equation
Dynamical behaviours and exact travelling wave solutions of ...
Indian Academy of Sciences (India)
2016-12-13
Dec 13, 2016 ... different types of solitons such as loops, humps and cusps. Meanwhile, Morrison ... solutions to the. mGVE using the auxiliary equation method [10] and a. 1 ... it is very important to do the qualitative analysis of the solutions. Here we ...... This research is supported by National Natural Sci- ence Foundation of ...
New binary travelling-wave periodic solutions for the modified KdV equation
International Nuclear Information System (INIS)
Yan Zhenya
2008-01-01
In this Letter, the modified Korteweg-de Vries (mKdV) equations with the focusing (+) and defocusing (-) branches are investigated, respectively. Many new types of binary travelling-wave periodic solutions are obtained for the mKdV equation in terms of Jacobi elliptic functions such as sn(ξ,m)cn(ξ,m)dn(ξ,m) and their extensions. Moreover, we analyze asymptotic properties of some solutions. In addition, with the aid of the Miura transformation, we also give the corresponding binary travelling-wave periodic solutions of KdV equation
Exact explicit travelling wave solutions for (n + 1)-dimensional Klein-Gordon-Zakharov equations
International Nuclear Information System (INIS)
Li Jibin
2007-01-01
Using the methods of dynamical systems for the (n + 1)-dimensional KGS nonlinear wave equations, five classes of exact explicit parametric representations of the bounded travelling solutions are obtained. To guarantee the existence of the above solutions, all parameter conditions are given
Exact Solutions to the Double Travelling Salesman Problem with Multiple Stacks
DEFF Research Database (Denmark)
Petersen, Hanne L.; Archetti, Claudia; Speranza, M. Grazia
2010-01-01
In this paper we present mathematical programming formulations and solution approaches for the optimal solution of the Double Travelling Salesman Problem with Multiple Stacks (DTSPMS). A set of orders is given, each one requiring transportation of one item from a customer in a pickup region...
Mean field effects for counterpropagating traveling wave solutions of reaction-diffusion systems
International Nuclear Information System (INIS)
Bernoff, A.J.; Kuske, R.; Matkowsky, B.J.; Volpert, V.
1995-01-01
In many problems, one observes traveling waves that propagate with constant velocity and shape in the χ direction, say, are independent of y, and z and describe transitions between two equilibrium states. As parameters of the system are varied, these traveling waves can become unstable and give rise to waves having additional structure, such as traveling waves in the y and z directions, which can themselves be subject to instabilities as parameters are further varied. To investigate this scenario the authors consider a system of reaction-diffusion equations with a traveling wave solution as a basic state. They determine solutions bifurcating from the basic state that describe counterpropagating traveling wave in directions orthogonal to the direction of propagation of the basic state and determine their stability. Specifically, they derive long wave modulation equations for the amplitudes of the counterpropagating traveling waves that are coupled to an equation for a mean field, generated by the translation of the basic state in the direction of its propagation. The modulation equations are then employed to determine stability boundaries to long wave perturbations for both unidirectional and counterpropagating traveling waves. The stability analysis is delicate because the results depend on the order in which transverse and longitudinal perturbation wavenumbers are taken to zero. For the unidirectional wave they demonstrate that it is sufficient to consider the cases of (1) purely transverse perturbations, (2) purely longitudinal perturbations, and (3) longitudinal perturbations with a small transverse component. These yield Eckhaus type, zigzag type, and skew type instabilities, respectively
Exact travelling wave solutions for some important nonlinear ...
Indian Academy of Sciences (India)
The study of nonlinear partial differential equations is an active area of research in applied mathematics, theoretical physics and engineering fields. In particular ... In [16–18], the author applied this method to construct the exact solutions of.
Classification of All Single Travelling Wave Solutions to Calogero-Degasperis-Focas Equation
International Nuclear Information System (INIS)
Liu Chengshi
2007-01-01
Under the travelling wave transformation, Calogero-Degasperis-Focas equation is reduced to an ordinary differential equation. Using a symmetry group of one parameter, this ODE is reduced to a second-order linear inhomogeneous ODE. Furthermore, we apply the change of the variable and complete discrimination system for polynomial to solve the corresponding integrals and obtained the classification of all single travelling wave solutions to Calogero-Degasperis-Focas equation.
Exact traveling wave solutions of the bbm and kdv equations using (G'/G)-expansion method
International Nuclear Information System (INIS)
Saddique, I.; Nazar, K.
2009-01-01
In this paper, we construct the traveling wave solutions involving parameters of the Benjamin Bona-Mahony (BBM) and KdV equations in terms of the hyperbolic, trigonometric and rational functions by using the (G'/G)-expansion method, where G = G(zeta) satisfies a second order linear ordinary differential equation. When the parameters are taken special values, the Solitary was are derived from the traveling waves. (author)
African Journals Online (AJOL)
homes very soon becomes a misplaced sentiment. However well planned a journey may be and how- ever important and tiring the attendances at meet- ings are, at some stage of every day the traveller finds himself in an hotel room and loneliness starts closing in from all four walls. No matter how luxu- rious the hotel may ...
Representations and Classification of Traveling Wave Solutions to sinh-Goerdon Equation
International Nuclear Information System (INIS)
Liu Chengshi
2008-01-01
Two concepts named atom solution and combinatory solution are defined. The classification of all single traveling wave atom solutions to sinh-Goerdon equation is obtained, and qualitative properties of solutions are discussed. In particular, we point out that some qualitative properties derived intuitively from dynamic system method are not true. Finally, we prove that our solutions to sinh-Goerdon equation include all solutions obtained in the paper [Z.T. Fu, et al., Commun. Theor. Phys. (Beijing, China) 45 (2006) 55]. Through an example, we show how to give some new identities on Jacobian elliptic functions.
Directory of Open Access Journals (Sweden)
Letlhogonolo Daddy Moleleki
2014-01-01
Full Text Available We analyze the (3+1-dimensional Boussinesq equation, which has applications in fluid mechanics. We find exact solutions of the (3+1-dimensional Boussinesq equation by utilizing the Lie symmetry method along with the simplest equation method. The solutions obtained are traveling wave solutions. Moreover, we construct the conservation laws of the (3+1-dimensional Boussinesq equation using the new conservation theorem, which is due to Ibragimov.
Analytical travelling wave solutions and parameter analysis for the ...
Indian Academy of Sciences (India)
done in the past few decades to improve this equation. Especially, in ... For exam- ple, the solutions of DS equation could describe the interaction between a ... In this paper, we consider the following (2+1)-dimensional Davey–Stewartson-type.
Travelling wave solutions to nonlinear physical models by means of ...
Indian Academy of Sciences (India)
Abstract. This paper presents the first integral method to carry out the integration of nonlinear ... NPDEs is an important and attractive research area. Not all ... cial types of analytic solutions to understand biological, physical and chemical phenomena ... Thus, based on the qualitative theory of ordinary differential equations.
Travelling wave solutions in a class of generalized Korteweg-de Vries equation
International Nuclear Information System (INIS)
Shen Jianwei; Xu Wei
2007-01-01
In this paper, we consider a new generalization of KdV equation u t = u x u l-2 + α[2u xxx u p + 4pu p-1 u x u xx + p(p - 1)u p-2 (u x ) 3 ] and investigate its bifurcation of travelling wave solutions. From the above analysis, we know that there exists compacton and cusp waves in the system. We explain the reason that these non-smooth travelling wave solution arise by using the bifurcation theory
International Nuclear Information System (INIS)
Zhang Huiqun
2009-01-01
By using a new coupled Riccati equations, a direct algebraic method, which was applied to obtain exact travelling wave solutions of some complex nonlinear equations, is improved. And the exact travelling wave solutions of the complex KdV equation, Boussinesq equation and Klein-Gordon equation are investigated using the improved method. The method presented in this paper can also be applied to construct exact travelling wave solutions for other nonlinear complex equations.
International Nuclear Information System (INIS)
Chen Yong; Wang Qi; Li Biao
2005-01-01
Based on a new general ansatz and a general subepuation, a new general algebraic method named elliptic equation rational expansion method is devised for constructing multiple travelling wave solutions in terms of rational special function for nonlinear evolution equations (NEEs). We apply the proposed method to solve Whitham-Broer-Kaup equation and explicitly construct a series of exact solutions which include rational form solitary wave solution, rational form triangular periodic wave solutions and rational wave solutions as special cases. In addition, the links among our proposed method with the method by Fan [Chaos, Solitons and Fractals 2004;20:609], are also clarified generally
Multiple travelling wave solutions of nonlinear evolution equations using a unified algebraic method
International Nuclear Information System (INIS)
Fan Engui
2002-01-01
A new direct and unified algebraic method for constructing multiple travelling wave solutions of general nonlinear evolution equations is presented and implemented in a computer algebraic system. Compared with most of the existing tanh methods, the Jacobi elliptic function method or other sophisticated methods, the proposed method not only gives new and more general solutions, but also provides a guideline to classify the various types of the travelling wave solutions according to the values of some parameters. The solutions obtained in this paper include (a) kink-shaped and bell-shaped soliton solutions, (b) rational solutions, (c) triangular periodic solutions and (d) Jacobi and Weierstrass doubly periodic wave solutions. Among them, the Jacobi elliptic periodic wave solutions exactly degenerate to the soliton solutions at a certain limit condition. The efficiency of the method can be demonstrated on a large variety of nonlinear evolution equations such as those considered in this paper, KdV-MKdV, Ito's fifth MKdV, Hirota, Nizhnik-Novikov-Veselov, Broer-Kaup, generalized coupled Hirota-Satsuma, coupled Schroedinger-KdV, (2+1)-dimensional dispersive long wave, (2+1)-dimensional Davey-Stewartson equations. In addition, as an illustrative sample, the properties of the soliton solutions and Jacobi doubly periodic solutions for the Hirota equation are shown by some figures. The links among our proposed method, the tanh method, extended tanh method and the Jacobi elliptic function method are clarified generally. (author)
International Nuclear Information System (INIS)
Feng Zhaosheng
2003-01-01
In this paper, we study the two-dimensional Burgers-Korteweg-de Vries (2D-BKdV) equation by analysing an equivalent two-dimensional autonomous system, which indicates that under some particular conditions, the 2D-BKdV equation has a unique bounded travelling wave solution. Then by using a direct method, a travelling solitary wave solution to the 2D-BKdV equation is expressed explicitly, which appears to be more efficient than the existing methods proposed in the literature. At the end of the paper, the asymptotic behaviour of the proper solutions of the 2D-BKdV equation is established by applying the qualitative theory of differential equations
Exact traveling wave solutions for a new nonlinear heat transfer equation
Directory of Open Access Journals (Sweden)
Gao Feng
2017-01-01
Full Text Available In this paper, we propose a new non-linear partial differential equation to de-scribe the heat transfer problems at the extreme excess temperatures. Its exact traveling wave solutions are obtained by using Cornejo-Perez and Rosu method.
DEFF Research Database (Denmark)
Petersen, Hanne Løhmann; Madsen, Oli B.G.
2009-01-01
This paper introduces the double travelling salesman problem with multiple stacks and presents four different metaheuristic approaches to its solution. The double TSP with multiple stacks is concerned with determining the shortest route performing pickups and deliveries in two separated networks...
Travelling wave solutions for a singularly perturbed Burgers–KdV ...
Indian Academy of Sciences (India)
This paper concerns with the existence problem of travelling wave solutions to a singularly perturbed Burgers–KdV equation. For this, we use the dynamical systems approach, specifically, the geometric singular perturbation theory and centre manifold theory. We also numerically show approximations, in particular, for ...
Exact traveling wave solution of nonlinear variants of the RLW and the PHI-four equations
Energy Technology Data Exchange (ETDEWEB)
Soliman, A.A. [Department of Mathematics, Faculty of Education (AL-Arish), Suez Canal University, AL-Arish 45111 (Egypt); Department of Mathematics, Teacher' s College, Bisha, P.O. Box 551 (Saudi Arabia)], E-mail: asoliman_99@yahoo.com
2007-08-27
By means of the modified extended tanh-function (METF) method the multiple traveling wave solutions of some different kinds of nonlinear partial differential equations are presented and implemented in a computer algebraic system. The solutions for the nonlinear equations such as variants of the RLW and variant of the PHI-four equations are exactly obtained and so the efficiency of the method can be demonstrated.
International Nuclear Information System (INIS)
Jun-Mao, Wang; Miao, Zhang; Wen-Liang, Zhang; Rui, Zhang; Jia-Hua, Han
2008-01-01
We present a new method to find the exact travelling wave solutions of nonlinear evolution equations, with the aid of the symbolic computation. Based on this method, we successfully solve the modified Benjamin–Bona–Mahoney equation, and obtain some new solutions which can be expressed by trigonometric functions and hyperbolic functions. It is shown that the proposed method is direct, effective and can be used for many other nonlinear evolution equations in mathematical physics. (general)
Exact travelling wave solutions of the Whitham-Broer-Kaup and Broer-Kaup-Kupershmidt equations
International Nuclear Information System (INIS)
Xu Guiqiong; Li Zhibin
2005-01-01
In this paper, an interesting fact is found that the auxiliary equation method is also applicable to a coupled system of two different equations involving both even-order and odd-order partial derivative terms. Furthermore, singular travelling wave solutions can also be obtained by considering other types of exact solutions of auxiliary equation. The Whitham-Broer-Kaup and the (2 + 1)-dimensional Broer-Kaup-Kupershmidt equations are chosen as examples to illustrate the effectiveness of the auxiliary equation method
Stability of a family of travelling wave solutions in a feedforward chain of phase oscillators
International Nuclear Information System (INIS)
Lanford, O E III; Mintchev, S M
2015-01-01
Travelling waves are an important class of signal propagation phenomena in extended systems with a preferred direction of information flow. We study the generation of travelling waves in unidirectional chains of coupled oscillators communicating via a phase-dependent pulse-response interaction borrowed from mathematical neuroscience. Within the context of such systems, we develop a widely applicable, jointly numerical and analytical methodology for deducing existence and stability of periodic travelling waves. We provide careful numerical studies that support the existence of a periodic travelling wave solution as well as the asymptotic relaxation of a single oscillator to the wave when it is forced with the wave profile. Using this evidence as an assumption, we analytically prove global stability of waves in the infinite chain, with respect to initial perturbations of downstream sites. This rigorous stability result suggests that asymptotic relaxation to the travelling wave occurs even when the forcing is perturbed from the wave profile, a property of the motivating system that is supported by previous work as well as the convergence of the more sophisticated numerical algorithm that we propose in order to compute a high-precision approximation to the solution. We provide additional numerical studies that show that the wave is part of a one-parameter family, and we illustrate the structural robustness of this family with respect to changes in the coupling strength. (paper)
On "new travelling wave solutions" of the KdV and the KdV-Burgers equations
Kudryashov, Nikolai A.
The Korteweg-de Vries and the Korteweg-de Vries-Burgers equations are considered. Using the travelling wave the general solutions of these equations are presented. "New travelling wave solutions" of the KdV and the KdV-Burgers equations by Wazzan [Wazzan L Commun Nonlinear Sci Numer Simulat
Travelling wave solutions of the Schamel–Korteweg–de Vries and the Schamel equations
Directory of Open Access Journals (Sweden)
Figen Kangalgil
2016-10-01
Full Text Available In this paper, the extended (G′/G-expansion method has been suggested for constructing travelling wave solutions of the Schamel–Korteweg–de Vries (s-KdV and the Schamel equations with aid of computer systems like Maple or Mathematica. The hyperbolic function solutions and the trigonometric function solutions with free parameters of these equations have been obtained. Moreover, it has been shown that the suggested method is elementary, effective and has been used to solve nonlinear evolution equations in applied mathematics, engineering and mathematical physics.
Traveling wave solutions for two nonlinear evolution equations with nonlinear terms of any order
International Nuclear Information System (INIS)
Feng Qing-Hua; Zhang Yao-Ming; Meng Fan-Wei
2011-01-01
In this paper, based on the known first integral method and the Riccati sub-ordinary differential equation (ODE) method, we try to seek the exact solutions of the general Gardner equation and the general Benjamin—Bona—Mahoney equation. As a result, some traveling wave solutions for the two nonlinear equations are established successfully. Also we make a comparison between the two methods. It turns out that the Riccati sub-ODE method is more effective than the first integral method in handling the proposed problems, and more general solutions are constructed by the Riccati sub-ODE method. (general)
Deltons, peakons and other traveling-wave solutions of a Camassa-Holm hierarchy
International Nuclear Information System (INIS)
Peng Xiaochun; Dai Huihui
2009-01-01
In this letter, we study an integrable Camassa-Holm hierarchy whose high-frequency limit is the Camassa-Holm equation. Phase plane analysis is employed to investigate bounded traveling wave solutions. An important feature is that there exists a singular line on the phase plane. By considering the properties of the equilibrium points and the relative position of the singular line, we find that there are in total three types of phase planes. Those paths in phase planes which represented bounded solutions are discussed one-by-one. Besides solitary, peaked and periodic waves, the equations are shown to admit a new type of traveling waves, which concentrate all their energy in one point, and we name them deltons as they can be expressed as some constant multiplied by a delta function. There also exists a type of traveling waves we name periodic deltons, which concentrate their energy in periodic points. The explicit expressions for them and all the other traveling waves are given.
Some Further Results on Traveling Wave Solutions for the ZK-BBM( Equations
Directory of Open Access Journals (Sweden)
Shaoyong Li
2013-01-01
Full Text Available We investigate the traveling wave solutions for the ZK-BBM( equations by using bifurcation method of dynamical systems. Firstly, for ZK-BBM(2, 2 equation, we obtain peakon wave, periodic peakon wave, and smooth periodic wave solutions and point out that the peakon wave is the limit form of the periodic peakon wave. Secondly, for ZK-BBM(3, 2 equation, we obtain some elliptic function solutions which include periodic blow-up and periodic wave. Furthermore, from the limit forms of the elliptic function solutions, we obtain some trigonometric and hyperbolic function solutions which include periodic blow-up, blow-up, and smooth solitary wave. We also show that our work extends some previous results.
Travelling wave solutions of the homogeneous one-dimensional FREFLO model
Huang, B.; Hong, J. Y.; Jing, G. Q.; Niu, W.; Fang, L.
2018-01-01
Presently there is quite few analytical studies in traffic flows due to the non-linearity of the governing equations. In the present paper we introduce travelling wave solutions for the homogeneous one-dimensional FREFLO model, which are expressed in the form of series and describe the procedure that vehicles/pedestrians move with a negative velocity and decelerate until rest, then accelerate inversely to positive velocities. This method is expect to be extended to more complex situations in the future.
Travelling wave solutions for a surface wave equation in fluid mechanics
Directory of Open Access Journals (Sweden)
Tian Yi
2016-01-01
Full Text Available This paper considers a non-linear wave equation arising in fluid mechanics. The exact traveling wave solutions of this equation are given by using G'/G-expansion method. This process can be reduced to solve a system of determining equations, which is large and difficult. To reduce this process, we used Wu elimination method. Example shows that this method is effective.
Conservation Laws and Traveling Wave Solutions of a Generalized Nonlinear ZK-BBM Equation
Directory of Open Access Journals (Sweden)
Khadijo Rashid Adem
2014-01-01
Full Text Available We study a generalized two-dimensional nonlinear Zakharov-Kuznetsov-Benjamin-Bona-Mahony (ZK-BBM equation, which is in fact Benjamin-Bona-Mahony equation formulated in the ZK sense. Conservation laws for this equation are constructed by using the new conservation theorem due to Ibragimov and the multiplier method. Furthermore, traveling wave solutions are obtained by employing the (G'/G-expansion method.
Traveling Wave Solutions of Reaction-Diffusion Equations Arising in Atherosclerosis Models
Directory of Open Access Journals (Sweden)
Narcisa Apreutesei
2014-05-01
Full Text Available In this short review article, two atherosclerosis models are presented, one as a scalar equation and the other one as a system of two equations. They are given in terms of reaction-diffusion equations in an infinite strip with nonlinear boundary conditions. The existence of traveling wave solutions is studied for these models. The monostable and bistable cases are introduced and analyzed.
Smooth and non-smooth traveling wave solutions of a class of nonlinear dispersive equation
International Nuclear Information System (INIS)
Zhao Xiaoshan; Wu Aidi; He Wenzhang
2009-01-01
There is the widespread existence of wave phenomena in physics, mechanics. This clearly necessitates a study of traveling waves in depth and of the modeling and analysis involved. In this paper, we study a nonlinear dispersive K(n,-n,2n) equation, which can be regarded as a generalized K(n,n) equation. Applying the bifurcation theory and the method of phase portraits analysis, we obtain the dynamical behavior and special exact solutions of the K(n,-n,2n) equation. As a result, the conditions under which peakon and compacton solutions appear are also given and the analytic expressions of peakon solutions, compacton and periodic cusp wave solutions are obtained.
Solute travel time in the vadose zone under RWMC at INEL
International Nuclear Information System (INIS)
Liou, J.C.P.; Tian, J.
1995-01-01
Solute transport in the vadose zone under the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering Laboratory (INEL) is considered. The objective is to assess the relative importance of variables involved in modeling the travel time of a conservative solute from ground surface to water table. The vadose zone under RWMC is composed of several layers of basalt flows interceded with sediment layers. The thickness of the layers varies with location. The hydraulic properties also vary. The extents of the variations are large, with standard deviations exceed mean in some instances. The vadose zone is idealized as composed of horizontal layers. Solute transport starts at the ground surface and moves vertically downwards to the water table. The perceived process is one-dimensional. This study used VS2DT, a computer code developed by the US Geological Survey, for simulating solute transport in variably saturated porous media
Travelling wave solutions for an infection-age structured epidemic model with external supplies
International Nuclear Information System (INIS)
Ducrot, Arnaud; Magal, Pierre
2011-01-01
The aim of this paper is to investigate the spatial invasion of some infectious disease. The contamination process is described by the age since infection. Compared with the classical Kermack and McKendrick's model, the vital dynamic is not omitted, and we allow some constant input flux into the population. This problem is rather natural in the context of epidemic problems and it has not been studied. Here we prove an existence and non-existence result for travelling wave solutions. We also describe the minimal wave speed. We are able to construct a suitable Lyapunov like functional decreasing along the travelling wave allowing to derive some qualitative properties, namely their convergence towards equilibrium points at x = ±∞
International Nuclear Information System (INIS)
Totović, A R; Crnjanski, J V; Krstić, M M; Gvozdić, D M
2014-01-01
In this paper, we analyze two semiconductor optical amplifier (SOA) structures, traveling-wave and reflective, with the active region made of the bulk material. The model is based on the stationary traveling-wave equations for forward and backward propagating photon densities of the signal and the amplified spontaneous emission, along with the stationary carrier rate equation. We start by introducing linear approximation of the carrier density spatial distribution, which enables us to find solutions for the photon densities in a closed analytical form. An analytical approach ensures a low computational resource occupation and an easy analysis of the parameters influencing the SOA’s response. The comparison of the analytical and numerical results shows high agreement for a wide range of the input optical powers and bias currents. (paper)
Yatim, Y. M.; Duffy, B. R.; Wilson, S. K.
2013-01-01
A novel family of three-dimensional travelling-wave similarity solutions describing a steadily translating slender dry patch in an infinitely wide thin fluid film on an inclined planar substrate when surface-tension effects are negligible
International Nuclear Information System (INIS)
Zhou Yubin; Li Chao
2009-01-01
A modified G'/G-expansion method is presented to derive traveling wave solutions for a class of nonlinear partial differential equations called Whitham-Broer-Kaup-Like equations. As a result, the hyperbolic function solutions, trigonometric function solutions, and rational solutions with parameters to the equations are obtained. When the parameters are taken as special values the solitary wave solutions can be obtained. (general)
Lu, Dianchen; Seadawy, Aly R.; Ali, Asghar
2018-06-01
In this current work, we employ novel methods to find the exact travelling wave solutions of Modified Liouville equation and the Symmetric Regularized Long Wave equation, which are called extended simple equation and exp(-Ψ(ξ))-expansion methods. By assigning the different values to the parameters, different types of the solitary wave solutions are derived from the exact traveling wave solutions, which shows the efficiency and precision of our methods. Some solutions have been represented by graphical. The obtained results have several applications in physical science.
Hierarchical Solution of the Traveling Salesman Problem with Random Dyadic Tilings
Kalmár-Nagy, Tamás; Bak, Bendegúz Dezső
We propose a hierarchical heuristic approach for solving the Traveling Salesman Problem (TSP) in the unit square. The points are partitioned with a random dyadic tiling and clusters are formed by the points located in the same tile. Each cluster is represented by its geometrical barycenter and a “coarse” TSP solution is calculated for these barycenters. Midpoints are placed at the middle of each edge in the coarse solution. Near-optimal (or optimal) minimum tours are computed for each cluster. The tours are concatenated using the midpoints yielding a solution for the original TSP. The method is tested on random TSPs (independent, identically distributed points in the unit square) up to 10,000 points as well as on a popular benchmark problem (att532 — coordinates of 532 American cities). Our solutions are 8-13% longer than the optimal ones. We also present an optimization algorithm for the partitioning to improve our solutions. This algorithm further reduces the solution errors (by several percent using 1000 iteration steps). The numerical experiments demonstrate the viability of the approach.
Time of travel of solutes in Buffalo Bayou and selected tributaries, Houston, Texas, August 1999
East, Jeffery W.; Schaer, Jasper D.
2000-01-01
The U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency, conducted a time-of-travel study in the Buffalo Bayou watershed during low flow in August 1999. The study was done as part of the U.S. Environmental Protection Agency Environmental Monitoring for Public Access and Community Tracking (EMPACT) program. The EMPACT program was designed for the U.S. Environmental Protection Agency to work with communities to “make timely, accurate, and understandable environmental information available to millions of people in the largest metropolitan areas across the country.” (U.S. Environmental Protection Agency, 2000). Buffalo Bayou, located in Houston, Texas, was chosen as a pilot project because it is a frequently used recreational water source, it has many water-treatment facilities located along its stream segments, and it has a history of water-quality problems (Houston-Galveston Area Council, 2000). One component of the pilot project is to develop a water-quality simulation model that can be used to assess the effects of noncompliance events on Buffalo Bayou. Because accurate estimates of time of travel during low flow are required to develop the model, the time of travel of solutes in Buffalo Bayou and selected tributaries was determined using dye tracing methods. The study was conducted during low flow in a 38.7-mile reach of Buffalo Bayou, a 9.6-mile reach of Whiteoak Bayou, a 5.9-mile reach of Mason Creek, and a 6.6-mile reach of Bear Creek. Efforts to determine the time of travel in a 7.5-mile reach of Horsepen Creek were unsuccessful. This report explains the approach used to conduct the study and presents the results of the study
Traveling waves in twisted nematic liquid crystal cells
International Nuclear Information System (INIS)
Zakharov, A.V.; Vakulenko, A.A.
2007-01-01
We have described a novel reorientation mechanism in the form of the traveling waves, under influence of an external electric field, directed parallel to both glass plates, which occur in the twisted nematic cell (TNC). It is found that the slowest velocity of the traveling front is proportional to the field strength, and, approximately, in three times higher than the front velocity corresponding to the non-traveling solution. The value of the critical electric field E cr which may excite the traveling waves in the TNC in π times less than the value of the threshold electric field E th corresponding to the untwisted geometry
Walterscheid, R. L.; Hecht, J. H.; Hickey, M. P.; Gelinas, L. J.; Vincent, R. A.; Reid, I. M.; Woithe, J.
2010-12-01
The Aerospace Corporation’s Nightglow Imager observed a large step-function change in airglow in the form of a traveling front in the OH and O2 airglow emissions over Alice Springs Australia on February 2, 2003. The front exhibited a stepwise increase of nearly a factor two in the OH brightness and a stepwise decrease in the O2 brightness. The change in brightness in each layer was associated with a strong leading disturbance followed by a train of weak barely visible waves. The OH airglow brightness behind the front was the brightness night for 02 at Alice Springs that we have measured in seven years of observations. The OH brightness was among the five brightest. The event was associated with a strong phase-locked two-day wave (TDW).We have analyzed the stability conditions for the upper mesosphere and lower thermosphere and found that the airglow layers were found in a region of strong ducting. The thermal structure was obtained from combining data from the SABER instrument on the TIMED satellite and the NRLMSISE-00 model. The wind profile was obtained by combining the HWM07 model and MF radar winds from Buckland Park Australia. We found that the TDW-disturbed profile was significantly more effective in supporting a high degree of ducting than a profile based only on HWM07 winds. Dramatic wall events have been interpreted as manifestations of undular bores (e.g., Smith et al. [2003]). Undular bores are nonlinear high Froude number events that must generate an ever increasing train of waves to carry the excess energy away from the bore front. Only a very weak wave train behind the initial disturbance was seen for the Alice Springs event. The form of the amplitude ordering was not typical of a nonlinear wave train. Therefore a bore interpretation requires another means of energy dissipation, namely turbulent dissipation. We suggest that a reasonable interpretation of the observed event is a turbulent bore. We are unaware of any previous event having
Directory of Open Access Journals (Sweden)
Rahmatullah
2018-03-01
Full Text Available We have computed new exact traveling wave solutions, including complex solutions of fractional order Boussinesq-Like equations, occurring in physical sciences and engineering, by applying Exp-function method. The method is blended with fractional complex transformation and modified Riemann-Liouville fractional order operator. Our obtained solutions are verified by substituting back into their corresponding equations. To the best of our knowledge, no other technique has been reported to cope with the said fractional order nonlinear problems combined with variety of exact solutions. Graphically, fractional order solution curves are shown to be strongly related to each other and most importantly, tend to fixate on their integer order solution curve. Our solutions comprise high frequencies and very small amplitude of the wave responses. Keywords: Exp-function method, New exact traveling wave solutions, Modified Riemann-Liouville derivative, Fractional complex transformation, Fractional order Boussinesq-like equations, Symbolic computation
Pištěková, Petra
2014-01-01
The thesis "Travel expenses" is dedicated to the travel expenses according to Czech legislation. The aim is to describe the travel reimbursement and to analyze the providing of compensation travel expenses on example of the elementary art school Zruč nad Sázavou. The purpose of this analysis is primarily to find an optimal solution to the problem of determining the place of regular workplace for the travel expenses. The theoretical part focuses on the identification and definition of all prin...
Approximate solutions for radial travel time and capture zone in unconfined aquifers.
Zhou, Yangxiao; Haitjema, Henk
2012-01-01
Radial time-of-travel (TOT) capture zones have been evaluated for unconfined aquifers with and without recharge. The solutions of travel time for unconfined aquifers are rather complex and have been replaced with much simpler approximate solutions without significant loss of accuracy in most practical cases. The current "volumetric method" for calculating the radius of a TOT capture zone assumes no recharge and a constant aquifer thickness. It was found that for unconfined aquifers without recharge, the volumetric method leads to a smaller and less protective wellhead protection zone when ignoring drawdowns. However, if the saturated thickness near the well is used in the volumetric method a larger more protective TOT capture zone is obtained. The same is true when the volumetric method is used in the presence of recharge. However, for that case it leads to unreasonableness over the prediction of a TOT capture zone of 5 years or more. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.
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Sachin Kumar
2012-10-01
Full Text Available Exact travelling wave solutions have been established for generalised sinh-Gordon andgeneralised (2+1 dimensional ZK-BBM equations by using GG expansion method whereG G( satisfies a second-order linear ordinary differential equation. The travelling wave solutionsare expressed by hyperbolic, trigonometric and rational functions.
Solution for a bipartite Euclidean traveling-salesman problem in one dimension
Caracciolo, Sergio; Di Gioacchino, Andrea; Gherardi, Marco; Malatesta, Enrico M.
2018-05-01
The traveling-salesman problem is one of the most studied combinatorial optimization problems, because of the simplicity in its statement and the difficulty in its solution. We characterize the optimal cycle for every convex and increasing cost function when the points are thrown independently and with an identical probability distribution in a compact interval. We compute the average optimal cost for every number of points when the distance function is the square of the Euclidean distance. We also show that the average optimal cost is not a self-averaging quantity by explicitly computing the variance of its distribution in the thermodynamic limit. Moreover, we prove that the cost of the optimal cycle is not smaller than twice the cost of the optimal assignment of the same set of points. Interestingly, this bound is saturated in the thermodynamic limit.
International Nuclear Information System (INIS)
Sandefur, R.L.; Grant, D.C.
1976-01-01
Studies of a roll-front uranium deposit in Shirley Basin Wyoming indicate that preliminary evaluation of the reserve potential of an ore body is possible with less drilling than currently practiced in industry. Estimating ore reserves from sparse drilling is difficult because most reserve calculation techniques do not give the accuracy of the estimate. A study of several deposits with a variety of drilling densities shows that geostatistics consistently provides a method of assessing the accuracy of an ore reserve estimate. Geostatistics provides the geologist with an additional descriptive technique - one which is valuable in the economic assessment of a uranium deposit. Closely spaced drilling on past properties provides both geological and geometric insight into the occurrence of uranium in roll-front type deposits. Just as the geological insight assists in locating new ore bodies and siting preferential drill locations, the geometric insight can be applied mathematically to evaluate the accuracy of a new ore reserve estimate. By expressing the geometry in numerical terms, geostatistics extracts important geological characteristics and uses this information to aid in describing the unknown characteristics of a property. (author)
Directory of Open Access Journals (Sweden)
Hasibun Naher
2012-01-01
Full Text Available We construct new analytical solutions of the (3+1-dimensional modified KdV-Zakharov-Kuznetsev equation by the Exp-function method. Plentiful exact traveling wave solutions with arbitrary parameters are effectively obtained by the method. The obtained results show that the Exp-function method is effective and straightforward mathematical tool for searching analytical solutions with arbitrary parameters of higher-dimensional nonlinear partial differential equation.
Schilde, M; Doerner, K F; Hartl, R F
2014-10-01
In urban areas, logistic transportation operations often run into problems because travel speeds change, depending on the current traffic situation. If not accounted for, time-dependent and stochastic travel speeds frequently lead to missed time windows and thus poorer service. Especially in the case of passenger transportation, it often leads to excessive passenger ride times as well. Therefore, time-dependent and stochastic influences on travel speeds are relevant for finding feasible and reliable solutions. This study considers the effect of exploiting statistical information available about historical accidents, using stochastic solution approaches for the dynamic dial-a-ride problem (dynamic DARP). The authors propose two pairs of metaheuristic solution approaches, each consisting of a deterministic method (average time-dependent travel speeds for planning) and its corresponding stochastic version (exploiting stochastic information while planning). The results, using test instances with up to 762 requests based on a real-world road network, show that in certain conditions, exploiting stochastic information about travel speeds leads to significant improvements over deterministic approaches.
Existence and exponential stability of traveling waves for delayed reaction-diffusion systems
Hsu, Cheng-Hsiung; Yang, Tzi-Sheng; Yu, Zhixian
2018-03-01
The purpose of this work is to investigate the existence and exponential stability of traveling wave solutions for general delayed multi-component reaction-diffusion systems. Following the monotone iteration scheme via an explicit construction of a pair of upper and lower solutions, we first obtain the existence of monostable traveling wave solutions connecting two different equilibria. Then, applying the techniques of weighted energy method and comparison principle, we show that all solutions of the Cauchy problem for the considered systems converge exponentially to traveling wave solutions provided that the initial perturbations around the traveling wave fronts belong to a suitable weighted Sobolev space.
Alam, Md Nur; Akbar, M Ali; Roshid, Harun-Or-
2014-01-01
Exact solutions of nonlinear evolution equations (NLEEs) play a vital role to reveal the internal mechanism of complex physical phenomena. In this work, the exact traveling wave solutions of the Boussinesq equation is studied by using the new generalized (G'/G)-expansion method. Abundant traveling wave solutions with arbitrary parameters are successfully obtained by this method and the wave solutions are expressed in terms of the hyperbolic, trigonometric, and rational functions. It is shown that the new approach of generalized (G'/G)-expansion method is a powerful and concise mathematical tool for solving nonlinear partial differential equations in mathematical physics and engineering. 05.45.Yv, 02.30.Jr, 02.30.Ik.
Directory of Open Access Journals (Sweden)
Shahnam Javadi
2013-07-01
Full Text Available In this paper, the $(G'/G$-expansion method is applied to solve a biological reaction-convection-diffusion model arising in mathematical biology. Exact traveling wave solutions are obtained by this method. This scheme can be applied to a wide class of nonlinear partial differential equations.
Solution of transient problems with steep gradients: novel front-tracking strategy
DEFF Research Database (Denmark)
Kiil, Søren; Bhatia, Suresh K.; Dam-Johansen, Kim
1995-01-01
and tested for the case of a gas-solid noncatalytic reaction in a porous solid at high Thiele modulus. Accurate and convergent steep profiles are obtained here for Thiele modulus larger than 50 for the case of slab as well as spherical geometry and found to match the analytical solution when it exists (such...
Directory of Open Access Journals (Sweden)
Katarzyna NOSAL
2015-06-01
Full Text Available Car traffic in cities causes a decrease in travel speed, irregularity of public transport operation and, as a consequence for travellers, significant time losses. Because of congestion the accessibility to the destination points, especially those that are located in the city centre, is threatened. Other difficulties concern: road safety, increasing air pollution, traffic noise and global warming. Construction of new roads and transport facilities requires large financial resources and covers large areas. City authorities implement many solutions to reduce these negative effects of car transport, including strategies which aim towards change in travel patterns. Inhabitants are encouraged to travel by more sustainable transport modes, including bikes. The concept is called travel demand management and in Poland is still a new approach to the passenger transport. This paper presents examples of instruments that are most commonly used abroad to encourage bike travels and an overview of the activities carried out to promote bike usage in Cracow. The paper also identifies Best Practices implemented in the area of Cracow and significant deficiencies in the basic issues and actions necessary to be undertaken in the future.
Energy Technology Data Exchange (ETDEWEB)
Ambrose, David M.; Wilkening, Jon
2008-12-11
We classify all bifurcations from traveling waves to non-trivial time-periodic solutions of the Benjamin-Ono equation that are predicted by linearization. We use a spectrally accurate numerical continuation method to study several paths of non-trivial solutions beyond the realm of linear theory. These paths are found to either re-connect with a different traveling wave or to blow up. In the latter case, as the bifurcation parameter approaches a critical value, the amplitude of the initial condition grows without bound and the period approaches zero. We propose a conjecture that gives the mapping from one bifurcation to its counterpart on the other side of the path of non-trivial solutions. By experimentation with data fitting, we identify the form of the exact solutions on the path connecting two traveling waves, which represents the Fourier coefficients of the solution as power sums of a finite number of particle positions whose elementary symmetric functions execute simple orbits in the complex plane (circles or epicycles). We then solve a system of algebraic equations to express the unknown constants in the new representation in terms of the mean, a spatial phase, a temporal phase, four integers (enumerating the bifurcation at each end of the path) and one additional bifurcation parameter. We also find examples of interior bifurcations from these paths of already non-trivial solutions, but we do not attempt to analyze their algebraic structure.
Directory of Open Access Journals (Sweden)
THEODOR VALENTIN PURCAREA
2010-06-01
Full Text Available Hospitality industry is probably the fastest growing one in the world. The tourism company should endeavour to shape the overall perception of value in this industry. What matters is the provision of experiences, but not services. To meet international standards the Romanian tourism should consider challenges, opportunities and solutions to cope with the specific requirements in this field.
Rahmatullah; Ellahi, Rahmat; Mohyud-Din, Syed Tauseef; Khan, Umar
2018-03-01
We have computed new exact traveling wave solutions, including complex solutions of fractional order Boussinesq-Like equations, occurring in physical sciences and engineering, by applying Exp-function method. The method is blended with fractional complex transformation and modified Riemann-Liouville fractional order operator. Our obtained solutions are verified by substituting back into their corresponding equations. To the best of our knowledge, no other technique has been reported to cope with the said fractional order nonlinear problems combined with variety of exact solutions. Graphically, fractional order solution curves are shown to be strongly related to each other and most importantly, tend to fixate on their integer order solution curve. Our solutions comprise high frequencies and very small amplitude of the wave responses.
METHOD OF ESTIMATING THE TRAVEL TIME OF NONINTERACTING SOLUTES THROUGH COMPACTED SOIL MATERIAL
The pollutant travel time through compacted soil material (i.e., when a pollutant introduced at the top first appears at the bottom) cannot be accurately predicted from the permeability (saturated hydraulic conductivity) alone. The travel time is also dependent on the effective p...
National Research Council Canada - National Science Library
Sanders, John W
2005-01-01
To evaluate the relationship between medical knowledge and clinical practice, a survey on travelers' diarrhea was administered to military health care providers attending a professional development...
Alam, Md Nur; Akbar, M Ali
2013-01-01
The new approach of the generalized (G'/G)-expansion method is an effective and powerful mathematical tool in finding exact traveling wave solutions of nonlinear evolution equations (NLEEs) in science, engineering and mathematical physics. In this article, the new approach of the generalized (G'/G)-expansion method is applied to construct traveling wave solutions of the Kadomtsev-Petviashvili-Benjamin-Bona-Mahony (KP-BBM) equation. The solutions are expressed in terms of the hyperbolic functions, the trigonometric functions and the rational functions. By means of this scheme, we found some new traveling wave solutions of the above mentioned equation.
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.
International Nuclear Information System (INIS)
Estevez, P G; Kuru, S; Negro, J; Nieto, L M
2006-01-01
The travelling wave solutions of the two-dimensional Korteweg-de Vries-Burgers and Kadomtsev-Petviashvili equations are studied from two complementary points of view. The first one is an adaptation of the factorization technique that provides particular as well as general solutions. The second one applies the Painleve analysis to both equations, throwing light on some aspects of the first method and giving an explanation to some restriction on the coefficients, as well as the relation between factorizations and integrals of motion
Geometric scaling as traveling waves
International Nuclear Information System (INIS)
Munier, S.; Peschanski, R.
2003-01-01
We show the relevance of the nonlinear Fisher and Kolmogorov-Petrovsky-Piscounov (KPP) equation to the problem of high energy evolution of the QCD amplitudes. We explain how the traveling wave solutions of this equation are related to geometric scaling, a phenomenon observed in deep-inelastic scattering experiments. Geometric scaling is for the first time shown to result from an exact solution of nonlinear QCD evolution equations. Using general results on the KPP equation, we compute the velocity of the wave front, which gives the full high energy dependence of the saturation scale
Dynamics and bifurcations of travelling wave solutions of R (m, n ...
Indian Academy of Sciences (India)
The qualitative change in the physical structures of these waves is shown to depend on the systemic parameters. Under different regions of parametric spaces, various sufficient conditions to guarantee the existence of the above waves are given. Moreover, some explicit exact parametric representations of travelling wave ...
Khater, Mostafa M. A.; Seadawy, Aly R.; Lu, Dianchen
2018-03-01
In this research, we investigate one of the most popular model in nature and also industrial which is the pressure equation of bubbly liquids with examination for viscosity and heat transfer which has many application in nature and engineering. Understanding the physical meaning of exact and solitary traveling wave solutions for this equation gives the researchers in this field a great clear vision of the pressure waves in a mixture liquid and gas bubbles taking into consideration the viscosity of liquid and the heat transfer and also dynamics of contrast agents in the blood flow at ultrasonic researches. To achieve our goal, we apply three different methods which are extended tanh-function method, extended simple equation method and a new auxiliary equation method on this equation. We obtained exact and solitary traveling wave solutions and we also discuss the similarity and difference between these three method and make a comparison between results that we obtained with another results that obtained with the different researchers using different methods. All of these results and discussion explained the fact that our new auxiliary equation method is considered to be the most general, powerful and the most result-oriented. These kinds of solutions and discussion allow for the understanding of the phenomenon and its intrinsic properties as well as the ease of way of application and its applicability to other phenomena.
Traveling-wave solutions in continuous chains of unidirectionally coupled oscillators
Glyzin, S. D.; Kolesov, A. Yu; Rozov, N. Kh
2017-12-01
Proposed is a mathematical model of a continuous annular chain of unidirectionally coupled generators given by certain nonlinear advection-type hyperbolic boundary value problem. Such problems are constructed by a limit transition from annular chains of unidirectionally coupled ordinary differential equations with an unbounded increase in the number of links. It is shown that any preassigned finite number of stable periodic motions of the traveling-wave type can coexist in the model.
Directory of Open Access Journals (Sweden)
Yair Zarmi
Full Text Available The (1+1-dimensional Sine-Gordon equation passes integrability tests commonly applied to nonlinear evolution equations. Its kink solutions (one-dimensional fronts are obtained by a Hirota algorithm. In higher space-dimensions, the equation does not pass these tests. Although it has been derived over the years for quite a few physical systems that have nothing to do with Special Relativity, the Sine-Gordon equation emerges as a non-linear relativistic wave equation. This opens the way for exploiting the tools of the Theory of Special Relativity. Using no more than the relativistic kinematics of tachyonic momentum vectors, from which the solutions are constructed through the Hirota algorithm, the existence and classification of N-moving-front solutions of the (1+2- and (1+3-dimensional equations for all N ≥ 1 are presented. In (1+2 dimensions, each multi-front solution propagates rigidly at one velocity. The solutions are divided into two subsets: Solutions whose velocities are lower than a limiting speed, c = 1, or are greater than or equal to c. To connect with concepts of the Theory of Special Relativity, c will be called "the speed of light." In (1+3-dimensions, multi-front solutions are characterized by spatial structure and by velocity composition. The spatial structure is either planar (rotated (1+2-dimensional solutions, or genuinely three-dimensional--branes. Planar solutions, propagate rigidly at one velocity, which is lower than, equal to, or higher than c. Branes must contain clusters of fronts whose speed exceeds c = 1. Some branes are "hybrids": different clusters of fronts propagate at different velocities. Some velocities may be lower than c but some must be equal to, or exceed, c. Finally, the speed of light cannot be approached from within the subset of slower-than-light solutions in both (1+2 and (1+3 dimensions.
Technology in rural transportation. Simple solution #6, traveler information on the internet
1997-01-01
This application was identified as a promising rural Intelligent Transportation Systems (ITS) solution under a project sponsored by the Federal Highway Administration (FHWA) and the ENTERPRISE program. This summary describes the solution as well as o...
Rigorous asymptotics of traveling-wave solutions to the thin-film equation and Tanner’s law
Giacomelli, Lorenzo; Gnann, Manuel V.; Otto, Felix
2016-09-01
We are interested in traveling-wave solutions to the thin-film equation with zero microscopic contact angle (in the sense of complete wetting without precursor) and inhomogeneous mobility {{h}3}+{λ3-n}{{h}n} , where h, λ, and n\\in ≤ft(\\frac{3}{2},\\frac{7}{3}\\right) denote film height, slip parameter, and mobility exponent, respectively. Existence and uniqueness of these solutions have been established by Maria Chiricotto and the first of the authors in previous work under the assumption of sub-quadratic growth as h\\to ∞ . In the present work we investigate the asymptotics of solutions as h\\searrow 0 (the contact-line region) and h\\to ∞ . As h\\searrow 0 we observe, to leading order, the same asymptotics as for traveling waves or source-type self-similar solutions to the thin-film equation with homogeneous mobility h n and we additionally characterize corrections to this law. Moreover, as h\\to ∞ we identify, to leading order, the logarithmic Tanner profile, i.e. the solution to the corresponding unperturbed problem with λ =0 that determines the apparent macroscopic contact angle. Besides higher-order terms, corrections turn out to affect the asymptotic law as h\\to ∞ only by setting the length scale in the logarithmic Tanner profile. Moreover, we prove that both the correction and the length scale depend smoothly on n. Hence, in line with the common philosophy, the precise modeling of liquid-solid interactions (within our model, the mobility exponent) does not affect the qualitative macroscopic properties of the film.
Orbital stability of periodic traveling-wave solutions for the log-KdV equation
Natali, Fábio; Pastor, Ademir; Cristófani, Fabrício
2017-09-01
In this paper we establish the orbital stability of periodic waves related to the logarithmic Korteweg-de Vries equation. Our motivation is inspired in the recent work [3], in which the authors established the well-posedness and the linear stability of Gaussian solitary waves. By using the approach put forward recently in [20] to construct a smooth branch of periodic waves as well as to get the spectral properties of the associated linearized operator, we apply the abstract theories in [13] and [25] to deduce the orbital stability of the periodic traveling waves in the energy space.
International Nuclear Information System (INIS)
Witte, N.S.
1997-01-01
The exact solution to the problem of reflection and diffraction of atomic de Broglie waves by a travelling evanescent wave is found starting with a bare-state formulation. The solution for the wavefunctions, the tunnelling losses and the non-adiabatic losses are given exactly in terms of hyper-Bessel functions, and are valid for all detuning and Rabi frequencies, thus generalizing previous approximate methods. Furthermore we give the limiting cases of all amplitudes in the uniform semiclassical limit, which is valid in all regions including near the classical turning points, and in the large and weak coupling cases. Exact results for the zero detuning case are obtained in terms of Bessel functions. We find our uniform semiclassical limit to be closer to the exact result over the full range of parameter values than the previously reported calculations. The current knowledge of hyper-Bessel function properties is reviewed in order to apply this to the physical problems imposed
Directory of Open Access Journals (Sweden)
Tarikul Islam
2018-03-01
Full Text Available In this article, the analytical solutions to the space-time fractional foam drainage equation and the space-time fractional symmetric regularized long wave (SRLW equation are successfully examined by the recently established rational (G′/G-expansion method. The suggested equations are reduced into the nonlinear ordinary differential equations with the aid of the fractional complex transform. Consequently, the theories of the ordinary differential equations are implemented effectively. Three types closed form traveling wave solutions, such as hyperbolic function, trigonometric function and rational, are constructed by using the suggested method in the sense of conformable fractional derivative. The obtained solutions might be significant to analyze the depth and spacing of parallel subsurface drain and small-amplitude long wave on the surface of the water in a channel. It is observed that the performance of the rational (G′/G-expansion method is reliable and will be used to establish new general closed form solutions for any other NPDEs of fractional order.
Dunlap, Lucas
2016-11-01
I argue that Deutsch's model for the behavior of systems traveling around closed timelike curves (CTCs) relies implicitly on a substantive metaphysical assumption. Deutsch is employing a version of quantum theory with a significantly supplemented ontology of parallel existent worlds, which differ in kind from the many worlds of the Everett interpretation. Standard Everett does not support the existence of multiple identical copies of the world, which the D-CTC model requires. This has been obscured because he often refers to the branching structure of Everett as a "multiverse", and describes quantum interference by reference to parallel interacting definite worlds. But he admits that this is only an approximation to Everett. The D-CTC model, however, relies crucially on the existence of a multiverse of parallel interacting worlds. Since his model is supplemented by structures that go significantly beyond quantum theory, and play an ineliminable role in its predictions and explanations, it does not represent a quantum solution to the paradoxes of time travel.
Traveling solitary wave solutions to evolution equations with nonlinear terms of any order
International Nuclear Information System (INIS)
Feng Zhaosheng
2003-01-01
Many physical phenomena in one- or higher-dimensional space can be described by nonlinear evolution equations, which can be reduced to ordinary differential equations such as the Lienard equation. Thus, to study those ordinary differential equations is of significance not only in mathematics itself, but also in physics. In this paper, a kind of explicit exact solutions to the Lienard equation is obtained. The applications of the solutions to the nonlinear RR-equation and the compound KdV-type equation are presented, which extend the results obtained in the previous literature
The General Traveling Wave Solutions of the Fisher Equation with Degree Three
Directory of Open Access Journals (Sweden)
Wenjun Yuan
2013-01-01
degree three and the general meromorphic solutions of the integrable Fisher equations with degree three, which improves the corresponding results obtained by Feng and Li (2006, Guo and Chen (1991, and Ağırseven and Öziş (2010. Moreover, all wg,1(z are new general meromorphic solutions of the Fisher equations with degree three for c=±3/2. Our results show that the complex method provides a powerful mathematical tool for solving a large number of nonlinear partial differential equations in mathematical physics.
Bakar, Sumarni Abu; Ibrahim, Milbah
2017-08-01
The shortest path problem is a popular problem in graph theory. It is about finding a path with minimum length between a specified pair of vertices. In any network the weight of each edge is usually represented in a form of crisp real number and subsequently the weight is used in the calculation of shortest path problem using deterministic algorithms. However, due to failure, uncertainty is always encountered in practice whereby the weight of edge of the network is uncertain and imprecise. In this paper, a modified algorithm which utilized heuristic shortest path method and fuzzy approach is proposed for solving a network with imprecise arc length. Here, interval number and triangular fuzzy number in representing arc length of the network are considered. The modified algorithm is then applied to a specific example of the Travelling Salesman Problem (TSP). Total shortest distance obtained from this algorithm is then compared with the total distance obtained from traditional nearest neighbour heuristic algorithm. The result shows that the modified algorithm can provide not only on the sequence of visited cities which shown to be similar with traditional approach but it also provides a good measurement of total shortest distance which is lesser as compared to the total shortest distance calculated using traditional approach. Hence, this research could contribute to the enrichment of methods used in solving TSP.
Photoionization effects in ionization fronts
International Nuclear Information System (INIS)
Arrayas, Manuel; Fontelos, Marco A; Trueba, Jose L
2006-01-01
In this paper we study the effects of photoionization processes on the propagation of both negative and positive ionization fronts in streamer discharge. We show that negative fronts accelerate in the presence of photoionization events. The appearance and propagation of positive ionization fronts travelling with constant velocity is explained as the result of the combined effects of photoionization and electron diffusion. The photoionization range plays an important role in the selection of the velocity of the ionization front as we show in this work
Photoionization effects in ionization fronts
Energy Technology Data Exchange (ETDEWEB)
Arrayas, Manuel [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain); Fontelos, Marco A [Departamento de Matematicas, Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones CientIficas, C/Serrano 123, 28006 Madrid (Spain); Trueba, Jose L [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)
2006-12-21
In this paper we study the effects of photoionization processes on the propagation of both negative and positive ionization fronts in streamer discharge. We show that negative fronts accelerate in the presence of photoionization events. The appearance and propagation of positive ionization fronts travelling with constant velocity is explained as the result of the combined effects of photoionization and electron diffusion. The photoionization range plays an important role in the selection of the velocity of the ionization front as we show in this work.
Yan, S.; Lin, H. C.; Jiang, X. Y.
2012-04-01
In this study the authors employ network flow techniques to construct a systematic model that helps ready mixed concrete carriers effectively plan production and truck dispatching schedules under stochastic travel times. The model is formulated as a mixed integer network flow problem with side constraints. Problem decomposition and relaxation techniques, coupled with the CPLEX mathematical programming solver, are employed to develop an algorithm that is capable of efficiently solving the problems. A simulation-based evaluation method is also proposed to evaluate the model, coupled with a deterministic model, and the method currently used in actual operations. Finally, a case study is performed using real operating data from a Taiwan RMC firm. The test results show that the system operating cost obtained using the stochastic model is a significant improvement over that obtained using the deterministic model or the manual approach. Consequently, the model and the solution algorithm could be useful for actual operations.
Yatim, Y. M.
2013-01-01
A novel family of three-dimensional travelling-wave similarity solutions describing a steadily translating slender dry patch in an infinitely wide thin fluid film on an inclined planar substrate when surface-tension effects are negligible is obtained, the flow being driven by gravity and/or a prescribed constant shear stress on the free surface of the film. For both driving mechanisms, the dry patch has a parabolic shape (which may be concave up or concave down the substrate), and the film thickness increases monotonically away from the contact lines to its uniform far-field value. The two most practically important cases of purely gravity-driven flow and of purely surface-shear-stress-driven flow are analysed separately. © 2013 AIP Publishing LLC.
Exact Travelling Wave Solutions for Isothermal Magnetostatic Atmospheres by Fan Subequation Method
Directory of Open Access Journals (Sweden)
Hossein Jafari
2012-01-01
ignorable coordinate corresponding to a uniform gravitational field in a plane geometry is carried out. These equations transform to a single nonlinear elliptic equation for the magnetic vector potential . This equation depends on an arbitrary function of that must be specified. With choices of the different arbitrary functions, we obtain analytical solutions of elliptic equation using the Fan subequation method.
Ericsson, Charles D
2003-02-01
Risk of travellers' diarrhoea is about 7% in developed countries and 20-50% in the developing world. Options for prevention include education and chemoprophylaxis. Vaccination is a promising but incomplete option. Achieving behaviour modification of food and water choices among tourists is difficult. Bismuth subsalicylate (BSS)-containing compounds are about 62% effective in the prevention of travellers' diarrhoea. Antibiotics are about 84% effective in preventing travellers' diarrhoea. Routine prophylaxis of travellers' diarrhoea, especially with antibiotics, should be discouraged. Oral rehydration is generally important in the treatment of diarrhoea, but travellers' diarrhoea is only infrequently dehydrating in adults. The addition of oral rehydration solutions confers no additional benefit to loperamide in the treatment of travellers' diarrhoea in adults. Presently, the most active of the antibiotics routinely available for treatment are members of the fluoroquinolone group. Antibiotics that are not absorbed such as aztreonam and a rifampicin-like agent, rifaximin, are both effective. The latter might become a therapy of choice once it is routinely available, due to predictably less adverse reactions with a non-absorbed antibiotic. Preliminary results with azithromycin look very promising. Less severe disease can be treated with a variety of non-antibiotic agents (e.g. BSS-containing compounds, loperamide and a calmodulin inhibitor, zaldaride). The combination of an antibiotic and loperamide is superior to treatment with either agent alone in a several studies and is arguably the treatment of choice for distressing travellers' diarrhoea.
US Agency for International Development — E2 Solutions is a web based end-to-end travel management tool that includes paperless travel authorization and voucher document submissions, document approval...
Directory of Open Access Journals (Sweden)
Rashida Hussain
2017-04-01
Full Text Available In this paper, Novel (Gʹ/G-expansion method is used to find new generalized exact travelling wave solutions of fractional order coupled Burger’s equations in terms of trigonometric functions, rational functions and hyperbolic functions with arbitrary parameters. For the conversion of the partial differential equation to the ordinary differential equation, complex transformation method is used. Novel (Gʹ/G-expansion method is very effective and provides a powerful mathematical tool to solve nonlinear equations. Moreover, for the representation of these exact solutions we have plotted graphs for different values of parameters which were in travelling waveform.
Parity-breaking front bifurcation in bistable media: link between discrete and continuous versions
International Nuclear Information System (INIS)
Pazo, Diego; Deza, Roberto R.; Perez-Munuzuri, Vicente
2005-01-01
The effect of space-discretization in the onset of traveling fronts in symmetrically bistable media is studied. For the FitzHugh-Nagumo model stable standing and propagating front solutions coexist. In the continuum limit this region of coexistence shrinks to a (double-zero eigenvalue) point. The unfolding of this point severely restricts the possible scenarios for the transition from standing to propagating fronts, such that the route described here and the one reported in [Phys. Rev. E 64 (2001) 065203(R)] are the most typical scenarios
International Nuclear Information System (INIS)
Chapman, N.; McKinley, I.; Shea, M.; Smellie, J.
1993-01-01
This article describes the investigations of redox fronts performed at the Osamu Utsumi mine. Results obtained by modelling groups on the rate of movement of the redox fronts and on the chemical reactions involved are discussed. Some of the most important rockwater interactions which occur at redox fronts can be modelled reasonably well but the complex redox chemistry of elements like sulphur is poorly simulated. The observed enrichment of many trace elements close to the redox fronts could be of significance for high-level waste repositories, but cannot be quantified by existing models. (author) 6 figs., 1 tab
Multiple travelling-wave solutions in a minimal model for cell motility
Kimpton, L. S.
2012-07-11
Two-phase flow models have been used previously to model cell motility. In order to reduce the complexity inherent with describing the many physical processes, we formulate a minimal model. Here we demonstrate that even the simplest 1D, two-phase, poroviscous, reactive flow model displays various types of behaviour relevant to cell crawling. We present stability analyses that show that an asymmetric perturbation is required to cause a spatially uniform, stationary strip of cytoplasm to move, which is relevant to cell polarization. Our numerical simulations identify qualitatively distinct families of travellingwave solutions that coexist at certain parameter values. Within each family, the crawling speed of the strip has a bell-shaped dependence on the adhesion strength. The model captures the experimentally observed behaviour that cells crawl quickest at intermediate adhesion strengths, when the substrate is neither too sticky nor too slippy. © The Author 2012. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.
Kyprianou, A.E.
2000-01-01
Recently Harris using probabilistic methods alone has given new proofs for the known existence asymptotics and unique ness of travelling wave solutions to the KPP equation Following in this vein we outline alternative probabilistic proofs for wave speeds exceeding the critical minimal wave speed
Directory of Open Access Journals (Sweden)
A. Kazakov
2016-12-01
Full Text Available The paper discusses a nonlinear parabolic equation describing the process of heat conduction for the case of the power dependence of the heat conductivity factor on temperature. Besides heat distribution in space, it describes filtration of a polytropic gas in a porous medium, whereupon, in the English-language literature, this equation is generally referred to as the porous medium equation. A distinctive feature of this equation is the degeneration of its parabolic type when the required function becomes zero, whereupon the equation acquires some properties typical of first-order equations. Particularly, in some cases, it proves possible to substantiate theorems of the existence and uniqueness of heat-wave (filtration-wave type solutions for it. This paper proves a theorem of the existence and uniqueness of the solution to the problem of the motion of a heat wave with a specified front in the instance of two independent variables. At that, since the front has the form of a closed plane curve, a transition t o the polar coordinate system is performed. The solution is constructed in the form of a series, a constructible recurrent procedure for calculating its coefficients being proposed. The series convergence is proved by the majorant method. A boundary-element-based computation algorithm in the form of a computer program has been developed and implemented to solve the problem under study. Test examples are considered, the calculations made by a program designed by the authors being compared with the truncated series. A good agreement of the obtained results has been established.
Travelling waves in models of neural tissue: from localised structures to periodic waves
Meijer, Hil Gaétan Ellart; Coombes, Stephen
2014-01-01
We consider travelling waves (fronts, pulses and periodics) in spatially extended one dimensional neural field models. We demonstrate for an excitatory field with linear adaptation that, in addition to an expected stable pulse solution, a stable anti-pulse can exist. Varying the adaptation strength
International Nuclear Information System (INIS)
Xu Rui; Chaplain, M.A.J.; Davidson, F.A.
2006-01-01
In this paper, we first investigate a stage-structured competitive model with time delays, harvesting, and nonlocal spatial effect. By using an iterative technique recently developed by Wu and Zou (Wu J, Zou X. Travelling wave fronts of reaction-diffusion systems with delay. J Dynam Differen Equat 2001;13:651-87), sufficient conditions are established for the existence of travelling front solution connecting the two boundary equilibria in the case when there is no positive equilibrium. The travelling wave front corresponds to an invasion by a stronger species which drives the weaker species to extinction. Secondly, we consider a stage-structured competitive model with time delays and nonlocal spatial effect when the domain is finite. We prove the global stability of each of the nonnegative equilibria and demonstrate that the more complex model studied here admits three possible long term behaviors: coexistence, bistability and dominance as is the case for the standard Lotka-Voltera competitive model
International Nuclear Information System (INIS)
Kumar, Vikas; Gupta, R. K.; Jiwari, Ram
2014-01-01
In this paper, the variable-coefficient diffusion—advection (DA) equation, which arises in modeling various physical phenomena, is studied by the Lie symmetry approach. The similarity reductions are derived by determining the complete sets of point symmetries of this equation, and then exact and numerical solutions are reported for the reduced second-order nonlinear ordinary differential equations. Further, an extended (G'/G)-expansion method is applied to the DA equation to construct some new non-traveling wave solutions
Directory of Open Access Journals (Sweden)
Rubén Iván Bolaños
2015-06-01
Full Text Available This paper considers a multi-objective version of the Multiple Traveling Salesman Problem (MOmTSP. In particular, two objectives are considered: the minimization of the total traveled distance and the balance of the working times of the traveling salesmen. The problem is formulated as an integer multi-objective optimization model. A non-dominated sorting genetic algorithm (NSGA-II is proposed to solve the MOmTSP. The solution scheme allows one to find a set of ordered solutions in Pareto fronts by considering the concept of dominance. Tests on real world instances and instances adapted from the literature show the effectiveness of the proposed algorithm.
Directory of Open Access Journals (Sweden)
M.G. Hafez
2016-06-01
Full Text Available In this paper, the novel (G′/G-expansion method is applied to construct exact travelling wave solutions of the cubic nonlinear Schrodinger equation. This technique is straightforward and simple to use, and gives more new general solutions than the other existing methods. Various types of solitary and periodic wave solutions of this equation are derived. The obtained results may be helpful to describe the wave propagation in soliton physics, such as soliton propagation in optical fibers, modulus instability in plasma physics, etc. and provided us the firm mathematical foundation in soliton physics or any varied instances. Furthermore, three-dimensional modules plot of the solutions are also given to visualize the dynamics of the equation.
Front propagation in flipping processes
International Nuclear Information System (INIS)
Antal, T; Ben-Avraham, D; Ben-Naim, E; Krapivsky, P L
2008-01-01
We study a directed flipping process that underlies the performance of the random edge simplex algorithm. In this stochastic process, which takes place on a one-dimensional lattice whose sites may be either occupied or vacant, occupied sites become vacant at a constant rate and simultaneously cause all sites to the right to change their state. This random process exhibits rich phenomenology. First, there is a front, defined by the position of the leftmost occupied site, that propagates at a nontrivial velocity. Second, the front involves a depletion zone with an excess of vacant sites. The total excess Δ k increases logarithmically, Δ k ≅ ln k, with the distance k from the front. Third, the front exhibits ageing-young fronts are vigorous but old fronts are sluggish. We investigate these phenomena using a quasi-static approximation, direct solutions of small systems and numerical simulations
International Nuclear Information System (INIS)
Ibrahim, R. S.; El-Kalaawy, O. H.
2006-01-01
The relativistic nonlinear self-consistent equations for a collisionless cold plasma with stationary ions [R. S. Ibrahim, IMA J. Appl. Math. 68, 523 (2003)] are extended to 3 and 3+1 dimensions. The resulting system of equations is reduced to the sine-Poisson equation. The truncated Painleve expansion and reduction of the partial differential equation to a quadrature problem (RQ method) are described and applied to obtain the traveling wave solutions of the sine-Poisson equation for stationary and nonstationary equations in 3 and 3+1 dimensions describing the charge-density equilibrium configuration model
Lu, Dianchen; Seadawy, Aly R.; Ali, Asghar
2018-06-01
The Equal-Width and Modified Equal-Width equations are used as a model in partial differential equations for the simulation of one-dimensional wave transmission in nonlinear media with dispersion processes. In this article we have employed extend simple equation method and the exp(-varphi(ξ)) expansion method to construct the exact traveling wave solutions of equal width and modified equal width equations. The obtained results are novel and have numerous applications in current areas of research in mathematical physics. It is exposed that our method, with the help of symbolic computation, provides a effective and powerful mathematical tool for solving different kind nonlinear wave problems.
Directory of Open Access Journals (Sweden)
Hüseyin Eldem
2017-08-01
Full Text Available Traveling Salesman Problem (TSP is a problem in combinatorial optimization that should be solved by a salesperson who has to travel all cities at the minimum cost (minimum route and return to the starting city (node. Todays, to resolve the minimum cost of this problem, many optimization algorithms have been used. The major ones are these metaheuristic algorithms. In this study, one of the metaheuristic methods, Ant Colony Optimization (ACO method (Max-Min Ant System – MMAS, was used to solve the Non-Euclidean TSP, which consisted of sets of different count points coincidentally located on the surface of a sphere. In this study seven point sets were used which have different point count. The performance of the MMAS method solving Non-Euclidean TSP problem was demonstrated by different experiments. Also, the results produced by ACO are compared with Discrete Cuckoo Search Algorithm (DCS and Genetic Algorithm (GA that are in the literature. The experiments for TSP on a sphere, show that ACO’s average results were better than the GA’s average results and also best results of ACO successful than the DCS.
Exact solutions of the one-dimensional generalized modified complex Ginzburg-Landau equation
International Nuclear Information System (INIS)
Yomba, Emmanuel; Kofane, Timoleon Crepin
2003-01-01
The one-dimensional (1D) generalized modified complex Ginzburg-Landau (MCGL) equation for the traveling wave systems is analytically studied. Exact solutions of this equation are obtained using a method which combines the Painleve test for integrability in the formalism of Weiss-Tabor-Carnevale and Hirota technique of bilinearization. We show that pulses, fronts, periodic unbounded waves, sources, sinks and solution as collision between two fronts are the important coherent structures that organize much of the dynamical properties of these traveling wave systems. The degeneracies of the 1D generalized MCGL equation are examined as well as several of their solutions. These degeneracies include two important equations: the 1D generalized modified Schroedinger equation and the 1D generalized real modified Ginzburg-Landau equation. We obtain that the one parameter family of traveling localized source solutions called 'Nozaki-Bekki holes' become a subfamily of the dark soliton solutions in the 1D generalized modified Schroedinger limit
Aw, Brian; Boraston, Suni; Botten, David; Cherniwchan, Darin; Fazal, Hyder; Kelton, Timothy; Libman, Michael; Saldanha, Colin; Scappatura, Philip; Stowe, Brian
2014-01-01
Abstract Objective To define the practice of travel medicine, provide the basics of a comprehensive pretravel consultation for international travelers, and assist in identifying patients who might require referral to travel medicine professionals. Sources of information Guidelines and recommendations on travel medicine and travel-related illnesses by national and international travel health authorities were reviewed. MEDLINE and EMBASE searches for related literature were also performed. Main message Travel medicine is a highly dynamic specialty that focuses on pretravel preventive care. A comprehensive risk assessment for each individual traveler is essential in order to accurately evaluate traveler-, itinerary-, and destination-specific risks, and to advise on the most appropriate risk management interventions to promote health and prevent adverse health outcomes during travel. Vaccinations might also be required and should be personalized according to the individual traveler’s immunization history, travel itinerary, and the amount of time available before departure. Conclusion A traveler’s health and safety depends on a practitioner’s level of expertise in providing pretravel counseling and vaccinations, if required. Those who advise travelers are encouraged to be aware of the extent of this responsibility and to refer all high-risk travelers to travel medicine professionals whenever possible. PMID:25500599
Energy Technology Data Exchange (ETDEWEB)
2016-06-01
The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.
International Nuclear Information System (INIS)
Ibrahim, R.S.
2003-01-01
The equations of magnetohydrodynamic (MHD) equilibria for a plasma in gravitational field are investigated. For equilibria with one ignorable spatial coordinate, the MHD equations are reduced to a single nonlinear elliptic equation for the magnetic potential u-tilde, known as the Grad-Shafranov equation. Specifying the arbitrary functions in this equation, the Bullough-Dodd equation can be obtained. The truncated Painleve expansion and reduction of the partial differential equation to a quadrature problem (RQ method) are described and applied to obtain the travelling wave solutions of the Bullough-Dodd equation for the case of isothermal magnetostatic atmosphere, in which the current density J is proportional to the exponentially of the magnetic flux and moreover falls off exponentially with distance vertical to the base, with an 'e-folding' distance equal to the gravitational scale height
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)
The homotopic method of travelling wave solution for El Niño tropic sea–air coupled oscillator
International Nuclear Information System (INIS)
Mo Jiaqi; Lin Wantao
2008-01-01
The EI Niño and Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific sea–air interactions. In this paper, an asymptotic method of solving nonlinear equations for the ENSO model is proposed. And based on a class of oscillator of the ENSO model and by employing the method of homotopic mapping, the approximate solution of equations for the corresponding ENSO model is studied. It is proved from the results that homotopic method can be used for analysing the sea surface temperature anomaly in the equatorial Pacific of the sea–air oscillator for the ENSO model
Travelling waves in expanding spatially homogeneous space–times
International Nuclear Information System (INIS)
Alekseev, George
2015-01-01
Some classes of the so-called ‘travelling wave’ solutions of Einstein and Einstein–Maxwell equations in general relativity and of dynamical equations for massless bosonic fields in string gravity in four and higher dimensions are presented. Similarly to the well known plane-fronted waves with parallel rays (pp-waves), these travelling wave solutions may depend on arbitrary functions of a null coordinate which determine the arbitrary profiles and polarizations of the waves. However, in contrast with pp-waves, these waves do not admit the null Killing vector fields and can exist in some curved (expanding and spatially homogeneous) background space–times, where these waves propagate in certain directions without any scattering. Mathematically, some of these classes of solutions arise as the fixed points of Kramer–Neugebauer transformations for hyperbolic integrable reductions of the above mentioned field equations or, in other cases, after imposing the ansatz that these waves do not change the part of the spatial metric transverse to the direction of wave propagation. It is worth noting that the strikingly simple forms of all the solutions presented prospectively make possible the consideration of the nonlinear interaction of these waves with the background curvature and singularities, as well as the collision of such wave pulses with solitons or with each other in the backgrounds where such travelling waves may exist. (paper)
Carlson Wagonlit Travel
2005-01-01
Dear customers, On 3 January we informed you that the airlines had decided to cease paying commission to travel agencies in Switzerland. This measure has since been progressively introduced, with rare exceptions. Consequently, in agreement with CERN, we are obliged to apply new transaction fees for private travel, with immediate effect. Carlson Wagonlit Travel (CWT) offers: A personalized, professional and competent consultancy service To seek the most economical and best solution adapted to your needs Neutrality in comparing prices and benefits Additional information concerning e.g. visa regulations, insurance, vaccinations, etc. Support in the event of problems We draw your attention to the fact that, in spite of the increase, these prices remain very competitive on today's market. Thank you for your trust and understanding. Yours truly, Carlson Wagonlit Travel CERN agency
Characteristic wave fronts in magnetohydrodynamics
International Nuclear Information System (INIS)
Menon, V.V.; Sharma, V.D.
1981-01-01
The influence of magnetic field on the process of steepening or flattening of the characteristic wave fronts in a plane and cylindrically symmetric motion of an ideal plasma is investigated. This aspect of the problem has not been considered until now. Remarkable differences between plane, cylindrical diverging, and cylindrical converging waves are discovered. The discontinuity in the velocity gradient at the wave front is shown to satisfy a Bernoulli-type equation. The discussion of the solutions of such equations reported in the literature is shown to be incomplete, and three general theorems are established. 18 refs
Stability of post-fertilization traveling waves
Flores, Gilberto; Plaza, Ramón G.
This paper studies the stability of a family of traveling wave solutions to the system proposed by Lane et al. [D.C. Lane, J.D. Murray, V.S. Manoranjan, Analysis of wave phenomena in a morphogenetic mechanochemical model and an application to post-fertilization waves on eggs, IMA J. Math. Appl. Med. Biol. 4 (4) (1987) 309-331], to model a pair of mechanochemical phenomena known as post-fertilization waves on eggs. The waves consist of an elastic deformation pulse on the egg's surface, and a free calcium concentration front. The family is indexed by a coupling parameter measuring contraction stress effects on the calcium concentration. This work establishes the spectral, linear and nonlinear orbital stability of these post-fertilization waves for small values of the coupling parameter. The usual methods for the spectral and evolution equations cannot be applied because of the presence of mixed partial derivatives in the elastic equation. Nonetheless, exponential decay of the directly constructed semigroup on the complement of the zero eigenspace is established. We show that small perturbations of the waves yield solutions to the nonlinear equations decaying exponentially to a phase-modulated traveling wave.
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Simonsen, Karen-Margrethe
2013-01-01
Review of "Travelling Concepts, Metaphors, and Narratives: Literary and Cultural Studies in an Age of Interdisciplinary Research" ed. by Sibylle Baumgarten, Beatrice Michaelis and Ansagar Nünning, Trier; Wissenschaftlicher Verlag Trier, 2012......Review of "Travelling Concepts, Metaphors, and Narratives: Literary and Cultural Studies in an Age of Interdisciplinary Research" ed. by Sibylle Baumgarten, Beatrice Michaelis and Ansagar Nünning, Trier; Wissenschaftlicher Verlag Trier, 2012...
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Barrett-Connor, E
1973-03-01
On the average, one-fourth of North Americans visiting developing countries experience a self-limited diarrheal illness that interferes with holiday or business activities. Recent work suggests that these episodes are caused by a small inoculum of enteropathogenic Escherichia coli which are common in the country visited and rare in the country of origin. Neither antimicrobial treatment nor anti-diarrheal agents have proven benefit once the illness has begun. Despite its frequent use, iodochlorhydroxyquin has not been shown in double blind studies to be effective as a preventive agent, and may be dangerous. The status of furazolidone for prevention of tourist diarrhea is questionable. Both neomycin sulfate and phythalylsulfathiazole have demonstrated efficacy as chemoprophylactics in Mexico. However, their use should be restricted to limited types of travel and travelers. General admonitions concerning avoidance of certain ingestibles are recommended; despite questionable value in preventing travelers' diarrhea such precautions may prevent more serious gastrointestinal illness.
Human travel and traveling bedbugs.
Delaunay, Pascal
2012-12-01
A dramatic increase of reported bedbug (Cimex lectularius and Cimex hemipterus) infestations has been observed worldwide over the past decade. Bedbug infestations have also been detected across a wide range of travel accommodations, regardless of their comfort and hygiene levels. Travelers are increasingly exposed to the risks of bedbug bites, infestation of personal belongings, and subsequent contamination of newly visited accommodations and their homes. We searched Medline publications via the PubMed database. National bedbug recommendations, textbooks, newspapers, and Centers for Disease Control websites were also searched manually. To detect infested sites, avoid or limit bedbug bites, and reduce the risk of contaminating one's belongings and home, bedbug biology and ecology must be understood. A detailed search of their most classic hiding niches is a key to finding adult bedbugs, nymphs, eggs, and feces or traces of blood from crushed bedbugs. Locally, bedbugs move by active displacement to feed (bite) during the night. Bed, mattress, sofa, and/or curtains are the most frequently infested places. If you find bedbugs, change your room or, even better, the hotel. Otherwise, travelers should follow recommendations for avoiding bedbugs and their bites during the night and apply certain simple rules to avoid infesting other sites or their home. Travelers exposed to bedbugs can minimize the risks of bites and infestation of their belongings, and must also do their civic duty to avoid contributing to the subsequent contamination of other hotels and, finally, home. © 2012 International Society of Travel Medicine.
DEFF Research Database (Denmark)
Rasmussen, Anders Rønne; Sørensen, Mads Peter; Gaididei, Yuri Borisovich
2011-01-01
A wave equation including nonlinear terms up to the second order for a thermoviscous Newtonian fluid is proposed. In the lossless case this equation results from an expansion to third order of the Lagrangian for the fundamental non-dissipative fluid dynamical equations. Thus it preserves the Hami...... is proposed. The dynamics of the rarefaction wave is approximated by a collective coordinate approach in the energy balance equation. © 2010 Springer Science+Business Media B.V.......A wave equation including nonlinear terms up to the second order for a thermoviscous Newtonian fluid is proposed. In the lossless case this equation results from an expansion to third order of the Lagrangian for the fundamental non-dissipative fluid dynamical equations. Thus it preserves...... the Hamiltonian structure, in contrast to the Kuznetsov equation, a model often used in nonlinear acoustics. An exact traveling wave front solution is derived from a generalized traveling wave assumption for the velocity potential. Numerical studies of the evolution of a number of arbitrary initial conditions...
DEFF Research Database (Denmark)
Hoeyer, Klaus
2016-01-01
In this paper, I argue that uncertainty and nonknowledge, and not just research results, can be important vehicles of translation through which genetic research participation comes to affect the lives of research participants. Based on interviews with participants in a genetic research project, I....... Research questions, and not just results, may serve as a generative form of knowledge that can travel as fast as any answer....
... other people who get dehydrated easily should drink rehydration solutions. Rehydration solutions help replace the fluid you lose while you are sick. You can buy packets of rehydration salts (to be mixed with safe water) at ...
International Nuclear Information System (INIS)
Igor Kaganovich
2000-01-01
Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas
Richardson, Leslie; Huber, Christopher; Loomis, John
2017-01-01
Remote and unique destinations present difficulties when attempting to construct traditional travel cost models to value recreation demand. The biggest limitation comes from the lack of variation in the dependent variable, defined as the number of trips taken over a set time frame. There are various approaches that can be used for overcoming limitations of the traditional travel cost model in the context of remote destinations. This study applies an adaptation of the standard model to estimate recreation benefits of bear viewing at Katmai National Park and Preserve in Alaska, which represents a once-in-a-lifetime experience for many visitors. Results demonstrate that visitors to this park’s Brooks Camp area are willing to pay an average of US$287 per day of bear viewing. Implications of these findings for valuing recreation at other remote destinations are discussed.
Multiple pulse traveling wave excitation of neon-like germanium
International Nuclear Information System (INIS)
Moreno, J. C.; Nilsen, J.; Silva, L. B. da
1995-01-01
Traveling wave excitation has been shown to significantly increase the output intensity of the neon-like germanium x-ray laser. The driving laser pulse consisted of three 100 ps Gaussian laser pulses separated by 400 ps. Traveling wave excitation was employed by tilting the wave front of the driving laser by 45 degrees to match the propagation speed of the x-ray laser photons along the length of the target. We show results of experiments with the traveling wave, with no traveling wave, and against the traveling wave and comparisons to a numerical model. Gain was inferred from line intensity measurements at two lengths
Traveling-wave synchronous coil gun
International Nuclear Information System (INIS)
Elliott, D.G.
1991-01-01
This paper reports on a traveling-wave synchronous coil gun which permits independent adjustment of the magnetic field and armature current for high velocity at low armature mass fraction. Magnetic field energy is transferred from the rear of the wave to the front without passing through the power supply. Elaborate switching is required
Energy Technology Data Exchange (ETDEWEB)
Richter, M.; Reinhardt, H.J.; Roschka, E.
1998-01-31
The catalytic conversion of a HC/CHC mixture in a travelling reaction front was investigated in order to apply the circulation reactor principle to the catalytic afterburning of CHC-burdened off-gas. The sub-project `circulating reaction zones` comprised a model-supported analysis and synthesis for establishing process control concepts using the methods of nonlinear dynamics. The experiment showed that the circulation reactor adjusts to different states of operation autonomously. The region of stable oscillation shifts as a result of (reversible) deactivation of the catalyst. With suitable process control measures, the position-dependent maximum temperature of the circulating reaction front can be kept within the catalyst-specific limiting values for total oxidation resp. catalyst damage. On the basis fo the investigations, a technically mature concept for use of the circulation reactor for decomposition of hard-to-crack pollutants was obtained provided that a suitable catalyst is available. The main field of application is the catalytic afterburning of varying pollutant volumes in low-volume off-gas streams in order to make use of the autonomous adaptation of the reactor to a new operating state in case of changing reaction conditions. [Deutsch] Im Rahmen dieses Teilprojektes wurde die katalytische Zersetzung eines Kohlenwasserstoff-Chlorkohlenwasserstoff-Gemischs in wandernder Reaktionsfront untersucht, um das Prinzip des Zirkulationsreaktors auf die katalytische Nachverbrennung von CKW-haltigen Abgasen anzuwenden. Im Teilprojekt `Zirkulierende Reaktionszonen` erfolgte die modellgestuetzte Analyse und Synthese zur Ableitung von Prozessfuehrungskonzepten mit den Methoden der nichtlinearen Dynamik. Bei den Versuchen konnte ein autonomes Einschwingen des Zirkulationsreaktors auf verschiedene Betriebszustaende experimentell nachgewiesen werden. Der Bereich stabiler Oszillation verschiebt sich infolge (reversibler) Desaktivierung des Katalysators. Mit geeigneten
Energy Technology Data Exchange (ETDEWEB)
Brodsky, S.
2004-11-30
In these lectures, I survey a number of applications of light-front methods to hadron and nuclear physics phenomenology and dynamics, including light-front statistical physics. Light-front Fock-state wavefunctions provide a frame-independent representation of hadrons in terms of their fundamental quark and gluon degrees of freedom. Nonperturbative methods for computing LFWFs in QCD are discussed, including string/gauge duality which predicts the power-law fall-off at high momentum transfer of light-front Fock-state hadronic wavefunctions with an arbitrary number of constituents and orbital angular momentum. The AdS/CFT correspondence has important implications for hadron phenomenology in the conformal limit, including an all-orders derivation of counting rules for exclusive processes. One can also compute the hadronic spectrum of near-conformal QCD assuming a truncated AdS/CFT space. Given the LFWFs, one can compute form factors, heavy hadron decay amplitudes, hadron distribution amplitudes, and the generalized parton distributions underlying deeply virtual Compton scattering. The quantum fluctuations represented by the light-front Fock expansion leads to novel QCD phenomena such as color transparency, intrinsic heavy quark distributions, diffractive dissociation, and hidden-color components of nuclear wavefunctions. A new test of hidden color in deuteron photodisintegration is proposed. The origin of leading-twist phenomena such as the diffractive component of deep inelastic scattering, single-spin asymmetries, nuclear shadowing and antishadowing is also discussed; these phenomena cannot be described by light-front wavefunctions of the target computed in isolation. Part of the anomalous NuTeV results for the weak mixing angle {theta}{sub W} could be due to the non-universality of nuclear antishadowing for charged and neutral currents.
International Nuclear Information System (INIS)
Reiser, M.
1982-01-01
An intense relativistic electron beam cannot propagate in a metal drift tube when the current exceeds the space charge limit. Very high charge density and electric field gradients (10 2 to 10 3 MV/m) develop at the beam front and the electrons are reflected. When a neutral gas or a plasma is present, collective acceleration of positive ions occur, and the resulting charge neutralization enables the beam to propagate. Experimental results, theoretical understanding, and schemes to achieve high ion energies by external control of the beam front velocity will be reviewed
Update on traveler's diarrhea.
Strum, W B
1988-07-01
Traveler's diarrhea affects a substantial number of travelers to high-risk areas of the world. The key to controlling this troublesome disease is prevention. The most important preventive measures depend on educating patients to consume only safe foods and pure water. Physicians cannot overemphasize the importance of avoiding high-risk foods and of boiling water if a safe water supply is not available. Prophylactic medications are a secondary consideration and should be prescribed with discretion. In most cases, diarrhea is mild and self-limited, requiring only fluid and electrolyte replacement and perhaps an antidiarrheal agent. In moderate to severe cases, the addition of an antimicrobial agent may be of benefit. Until an efficacious polyvalent vaccine is developed, caution and common sense, together with discretionary dietary and hygienic practices, are the best defenses against traveler's diarrhea. The ultimate solution is greatly improved sanitation and personal hygiene, especially in high-risk countries. However, only dreamers will consider waiting for this transformation to occur.
Travelers' Health: HIV Infection
... Last-Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ... for purposes of medical treatment (see Chapter 2, Medical Tourism ), the blood and blood products used in the ...
International travel and vaccinations.
Rizvon, M K; Qazi, S; Ward, L A
1999-01-01
With the increase in global travel, no disease is beyond the reach of any population. Traveling patients should be advised to follow food and water precautions and encouraged to receive the recommended immunizations. Travel medicine plays a vital role not only in limiting the morbidity of travel-related illnesses but also in limiting the spread of diseases. This article addresses the common issues related to travel, reviews the care of the immunocompromised traveler, and updates the available...
Parametric form of QCD travelling waves
Peschanski, R.
2005-01-01
We derive parametric travelling-wave solutions of non-linear QCD equations. They describe the evolution towards saturation in the geometric scaling region. The method, based on an expansion in the inverse of the wave velocity, leads to a solvable hierarchy of differential equations. A universal parametric form of travelling waves emerges from the first two orders of the expansion.
Energy Technology Data Exchange (ETDEWEB)
2016-12-21
The JMP Add-In TopN-PFS provides an automated tool for finding layered Pareto front to identify the top N solutions from an enumerated list of candidates subject to optimizing multiple criteria. The approach constructs the N layers of Pareto fronts, and then provides a suite of graphical tools to explore the alternatives based on different prioritizations of the criteria. The tool is designed to provide a set of alternatives from which the decision-maker can select the best option for their study goals.
Discretionary Power on the Front-line
DEFF Research Database (Denmark)
Sanden, Guro Refsum; Lønsmann, Dorte
This article investigates the communication practices used by front-line employees to cross language boundaries in the context of English language policies implemented by the management of three multinational corporations (MNCs) headquartered in Scandinavia. Based on an analysis of interview...... and document data, our findings show that employees face a number of different language boundaries in their everyday work, and that ad hoc and informal solutions in many cases are vital for successful cross-language communication. We introduce the concept of ‘discretionary power’ to explain how and why front...
DEFF Research Database (Denmark)
Sanden, Guro Refsum; Lønsmann, Dorte
language boundaries in their everyday work. Despite official English language policies in the three companies, our findings show that employees face a number of different language boundaries, and that ad hoc and informal solutions in many cases are vital for successful cross-language communication. Drawing......This article investigates how front-line employees respond to English language policies implemented by the management of three multinational corporations (MNCs) headquartered in Scandinavia. Based on interview and document data the article examines the ways in which front-line employees cross...
Discretionary power on the front-line
DEFF Research Database (Denmark)
Sanden, Guro Refsum; Lønsmann, Dorte
2018-01-01
This article investigates the communication practices used by front-line employees to cross language boundaries in the context of English language policies implemented by the management of three multinational corporations headquartered in Scandinavia. Based on an analysis of interview and document...... data, our findings show that employees face a number of different language boundaries in their everyday work, and that ad hoc and informal solutions in many cases are vital for successful cross-language communication. We introduce the concept of discretionary power to explain how and why front...
Discretionary Power on the Front Line
DEFF Research Database (Denmark)
Sanden, Guro Refsum; Lønsmann, Dorte
2018-01-01
This paper investigates the communication practices used by front-line employees to cross language boundaries in the context of English language policies implemented by the management of three multinational corporations (MNCs) headquartered in Scandinavia. Based on an analysis of interview...... and document data, our findings show that employees face a number of different language boundaries in their everyday work, and that ad hoc and informal solutions in many cases are vital for successful cross-language communication. We introduce the concept of 'discretionary power' to explain how and why front...
Energy Technology Data Exchange (ETDEWEB)
Young, Stanley
2017-04-24
The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing energy efficient travel behavior.
International Nuclear Information System (INIS)
Wendroff, B.
1988-01-01
The cooling of hot surfaces can be modeled in certain simples cases by a nonlinear eigenvalue problem describing the motion of a steady traveling cooling wave. Earlier work on the mathematical theory, the numerical analysis, and the asymptotics of this problem are reviewed
Friction forces on phase transition fronts
International Nuclear Information System (INIS)
Mégevand, Ariel
2013-01-01
In cosmological first-order phase transitions, the microscopic interaction of the phase transition fronts with non-equilibrium plasma particles manifests itself macroscopically as friction forces. In general, it is a nontrivial problem to compute these forces, and only two limits have been studied, namely, that of very slow walls and, more recently, ultra-relativistic walls which run away. In this paper we consider ultra-relativistic velocities and show that stationary solutions still exist when the parameters allow the existence of runaway walls. Hence, we discuss the necessary and sufficient conditions for the fronts to actually run away. We also propose a phenomenological model for the friction, which interpolates between the non-relativistic and ultra-relativistic values. Thus, the friction depends on two friction coefficients which can be calculated for specific models. We then study the velocity of phase transition fronts as a function of the friction parameters, the thermodynamic parameters, and the amount of supercooling
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J.; de Teramond, Guy F.; /SLAC /Southern Denmark U., CP3-Origins /Costa Rica U.
2011-01-10
AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. The hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. Higher Fock states with extra quark-anti quark pairs also arise. The soft-wall model also predicts the form of the nonperturbative effective coupling and its {beta}-function. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method to systematically include QCD interaction terms. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.
International Nuclear Information System (INIS)
Brodsky, Stanley J.; de Teramond, Guy F.
2011-01-01
AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate ζ which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. The hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. Higher Fock states with extra quark-anti quark pairs also arise. The soft-wall model also predicts the form of the nonperturbative effective coupling and its β-function. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method to systematically include QCD interaction terms. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.
Pelce, Pierre
1989-01-01
In recent years, much progress has been made in the understanding of interface dynamics of various systems: hydrodynamics, crystal growth, chemical reactions, and combustion. Dynamics of Curved Fronts is an important contribution to this field and will be an indispensable reference work for researchers and graduate students in physics, applied mathematics, and chemical engineering. The book consist of a 100 page introduction by the editor and 33 seminal articles from various disciplines.
Radiative thermal conduction fronts
International Nuclear Information System (INIS)
Borkowski, K.J.; Balbus, S.A.; Fristrom, C.C.
1990-01-01
The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence
Herrmann, Tim; Mallow, Johannes; Plaumann, Markus; Luchtmann, Michael; Stadler, Jörg; Mylius, Judith; Brosch, Michael; Bernarding, Johannes
2015-01-01
Neuroimaging of macaques at ultra-high field (UHF) is usually conducted by combining a volume coil for transmit (Tx) and a phased array coil for receive (Rx) tightly enclosing the monkey's head. Good results have been achieved using vertical or horizontal magnets with implanted or near-surface coils. An alternative and less costly approach, the travelling-wave (TW) excitation concept, may offer more flexible experimental setups on human whole-body UHF magnetic resonance imaging (MRI) systems, which are now more widely available. Goal of the study was developing and validating the TW concept for in vivo primate MRI. The TW Primate System (TWPS) uses the radio frequency shield of the gradient system of a human whole-body 7 T MRI system as a waveguide to propagate a circularly polarized B1 field represented by the TE11 mode. This mode is excited by a specifically designed 2-port patch antenna. For receive, a customized neuroimaging monkey head receive-only coil was designed. Field simulation was used for development and evaluation. Signal-to-noise ratio (SNR) was compared with data acquired with a conventional monkey volume head coil consisting of a homogeneous transmit coil and a 12-element receive coil. The TWPS offered good image homogeneity in the volume-of-interest Turbo spin echo images exhibited a high contrast, allowing a clear depiction of the cerebral anatomy. As a prerequisite for functional MRI, whole brain ultrafast echo planar images were successfully acquired. The TWPS presents a promising new approach to fMRI of macaques for research groups with access to a horizontal UHF MRI system.
Directory of Open Access Journals (Sweden)
Tim Herrmann
Full Text Available Neuroimaging of macaques at ultra-high field (UHF is usually conducted by combining a volume coil for transmit (Tx and a phased array coil for receive (Rx tightly enclosing the monkey's head. Good results have been achieved using vertical or horizontal magnets with implanted or near-surface coils. An alternative and less costly approach, the travelling-wave (TW excitation concept, may offer more flexible experimental setups on human whole-body UHF magnetic resonance imaging (MRI systems, which are now more widely available. Goal of the study was developing and validating the TW concept for in vivo primate MRI.The TW Primate System (TWPS uses the radio frequency shield of the gradient system of a human whole-body 7 T MRI system as a waveguide to propagate a circularly polarized B1 field represented by the TE11 mode. This mode is excited by a specifically designed 2-port patch antenna. For receive, a customized neuroimaging monkey head receive-only coil was designed. Field simulation was used for development and evaluation. Signal-to-noise ratio (SNR was compared with data acquired with a conventional monkey volume head coil consisting of a homogeneous transmit coil and a 12-element receive coil.The TWPS offered good image homogeneity in the volume-of-interest Turbo spin echo images exhibited a high contrast, allowing a clear depiction of the cerebral anatomy. As a prerequisite for functional MRI, whole brain ultrafast echo planar images were successfully acquired.The TWPS presents a promising new approach to fMRI of macaques for research groups with access to a horizontal UHF MRI system.
Spatiotemporal chaos in the dynamics of buoyantly and diffusively unstable chemical fronts
Baroni, M. P. M. A.; Guéron, E.; De Wit, A.
2012-03-01
Nonlinear dynamics resulting from the interplay between diffusive and buoyancy-driven Rayleigh-Taylor (RT) instabilities of autocatalytic traveling fronts are analyzed numerically for various values of the relevant parameters. These are the Rayleigh numbers of the reactant A and autocatalytic product B solutions as well as the ratio D =DB/DA between the diffusion coefficients of the two key chemical species. The interplay between the coarsening dynamics characteristic of the RT instability and the constant short wavelength modulation of the diffusive instability can lead in some regimes to complex dynamics dominated by irregular succession of birth and death of fingers. By using spectral entropy measurements, we characterize the transition between order and spatial disorder in this system. The analysis of the power spectrum and autocorrelation function, moreover, identifies similarities between the various spatial patterns. The contribution of the diffusive instability to the complex dynamics is discussed.
Curved fronts in the Belousov-Zhabotinskii reaction-diffusion systems in R2
Niu, Hong-Tao; Wang, Zhi-Cheng; Bu, Zhen-Hui
2018-05-01
In this paper we consider a diffusion system with the Belousov-Zhabotinskii (BZ for short) chemical reaction. Following Brazhnik and Tyson [4] and Pérez-Muñuzuri et al. [45], who predicted V-shaped fronts theoretically and discovered V-shaped fronts by experiments respectively, we give a rigorous mathematical proof of their results. We establish the existence of V-shaped traveling fronts in R2 by constructing a proper supersolution and a subsolution. Furthermore, we establish the stability of the V-shaped front in R2.
Directory of Open Access Journals (Sweden)
Reinhold Steinacker
2016-12-01
Full Text Available In 1906, the Austrian scientist Max Margules published a paper on temperature stratification in resting and non-accelerated moving air. The paper derives conditions for stationary slopes of air mass boundaries and was an important forerunner of frontal theories. Its formulation of relations between changes in density and geostrophic wind across the front is basically a discrete version of the thermal wind balance equation. The paper was highly influential and is still being cited to the present day. This paper accompanies an English translation of Margules’ seminal paper. We conclude here our “Classic Papers” series of the Meteorologische Zeitschrift.
Puttkamer, J. V.
1973-01-01
An analysis has been conducted to find out whether the management techniques developed in connection with the Apollo project could be used for dealing with such urgent problems of modern society as the crisis of the cities, the increasing environmental pollution, and the steadily growing traffic. Basic concepts and definitions of program and system management are discussed together with details regarding the employment of these concepts in connection with the solution of the problems of the Apollo program. Principles and significance of a systems approach are considered, giving attention to planning, system analysis, system integration, and project management. An application of the methods of project management to the problems of the civil sector is possible if the special characteristics of each particular case are taken into account.
Zuckerman, Jane N; Leggat, Peter
2015-01-01
This 1st edition of Essential Travel Medicine provides an excellent concise introduction to the specialty of Travel Medicine. This core text will enable health care practitioners particularly those new to the clinical practice of Travel Medicine, to gain a fundamental understanding of the diverse and complex issues which can potentially affect the health of the many millions of people who undertake international travel. Jane N Zuckerman is joined by Gary W Brunette from CDC and Peter A Leggat from Australia as Editors. Leading international specialists in their fields have contributed authoritative chapters reflecting current knowledge to facilitate best clinical practice in the different aspects of travel medicine. The aim of Essential Travel Medicine is to provide a comprehensive guide to Travel Medicine as well as a fundamental knowledge base to support international undergraduate and postgraduate specialty training programmes in the discipline of Travel Medicine. The 1st edition of Essential Travel ...
Stability of cosmological detonation fronts
Mégevand, Ariel; Membiela, Federico Agustín
2014-05-01
The steady-state propagation of a phase-transition front is classified, according to hydrodynamics, as a deflagration or a detonation, depending on its velocity with respect to the fluid. These propagation modes are further divided into three types, namely, weak, Jouguet, and strong solutions, according to their disturbance of the fluid. However, some of these hydrodynamic modes will not be realized in a phase transition. One particular cause is the presence of instabilities. In this work we study the linear stability of weak detonations, which are generally believed to be stable. After discussing in detail the weak detonation solution, we consider small perturbations of the interface and the fluid configuration. When the balance between the driving and friction forces is taken into account, it turns out that there are actually two different kinds of weak detonations, which behave very differently as functions of the parameters. We show that the branch of stronger weak detonations are unstable, except very close to the Jouguet point, where our approach breaks down.
Traveling waves in a spring-block chain sliding down a slope
Morales, J. E.; James, G.; Tonnelier, A.
2017-07-01
Traveling waves are studied in a spring slider-block model. We explicitly construct front waves (kinks) for a piecewise-linear spinodal friction force. Pulse waves are obtained as the matching of two traveling fronts with identical speeds. Explicit formulas are obtained for the wavespeed and the wave form in the anticontinuum limit. The link with localized waves in a Burridge-Knopoff model of an earthquake fault is briefly discussed.
Travelling waves in heterogeneous media
Boden, Adam
2013-01-01
In this thesis we study the existence of travelling wave type solutions for a reaction diffusion equation in R2 with a nonlinearity which depends periodically on the spatial variable. Specifically we will consider a particular class of nonlinearities where we treat the coefficient of the linear term as a parameter. For this class of nonlinearities we formulate the problem as a spatial dynamical system and use a centre manifold reduction to find conditions on the parameter and nonlinearity for...
DEFF Research Database (Denmark)
Nielsen, Ulla S; Jensen-Fangel, Søren; Pedersen, Gitte
2014-01-01
BACKGROUND: We aimed to describe travel patterns, extent of professional pre-travel advice and health problems encountered during travel among HIV-infected individuals. METHODS: During a six-month period a questionnaire was handed out to 2821 adult HIV-infected individuals attending any...... of the eight Danish medical HIV care centers. RESULTS: A total of 763 individuals responded. During the previous two years 49% had travelled outside Europe; 18% had travelled less and 30% were more cautious when choosing travel destination than before the HIV diagnosis. Pre-travel advice was sought by only 38......%, and travel insurance was taken out by 86%. However, 29%/74% did not inform the advisor/the insurance company about their HIV status. Nearly all patients on highly active antiretroviral therapy (HAART) were adherent, but 58% worried about carrying HIV-medicine and 19% tried to hide it. Only 19% experienced...
... on traveling and dining out at restaurants with food allergies. Travel Tips for the U.S. and Other Countries Get information about medications and food labeling practices in select countries. Spam Control Text: ...
Schuhwerk, M A; Richens, J; Zuckerman, Jane N
2006-01-01
There is a high demand for travel among HIV-positive individual. This demand arises partly from those who have benefited from advances in antiretroviral therapy as well as those with disease progression. The key to a successful and uneventful holiday lies in careful pre-trip planning, yet many patients fail to obtain advice before travelling. Travel advice for HIV patients is becoming increasingly specialized. In addition to advice on common travel-related infectious diseases, HIV-positive travellers are strongly advised to carry information with them and they need specific advice regarding country entry restrictions, HIV inclusive travel insurance, safety of travel vaccinations and highly active antiretroviral therapy-related issues. A wide range of relevant issues for the HIV-positive traveller are discussed in this review and useful websites can be found at the end.
Traveling Safely with Medicines
... Medications Safely My Medicine List How to Administer Traveling Safely with Medicines Planes, trains, cars – even boats ... your trip, ask your pharmacist about how to travel safely with your medicines. Make sure that you ...
Travelers' Health: Leishmaniasis, Visceral
... such as the United States reflects travel and immigration patterns. VL is uncommon in US travelers and ... whqlibdoc.who.int/trs/WHO_TRS_949_eng.pdf . Chapter 3 - Leishmaniasis, Cutaneous Chapter 3 - Leptospirosis File ...
... Videos for Educators Search English Español Traveling and Asthma KidsHealth / For Kids / Traveling and Asthma Print en ... pack it, too. How Can I Avoid My Asthma Triggers? Staying at a hotel Ask for a ...
International Nuclear Information System (INIS)
Gregg, D.W.; Kidder, R.E.; Biehl, A.T.
1975-01-01
A method is described for generating a traveling wave laser pulse of almost unlimited energy content wherein a gain medium is pumped into a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)
Travel, infection and immunity
Soonawala, Darius
2016-01-01
Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use immunosuppressants or who have chronic diseases. The clinic is closely connected to the department of Infectious Diseases at LUMC. The setting of a travel clinic within an academic medical hospital, provides unique...
Travel, infection and immunity
Soonawala, Darius
2016-01-01
Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use
British Columbia Dept. of Education, Victoria.
Written for college entry-level travel agent training courses, this course outline can also be used for inservice training programs offered by travel agencies. The outline provides information on the work of a travel agent and gives clear statements on what learners must be able to do by the end of their training. Material is divided into eight…
Zheng, F.
2011-01-01
Urban travel times are intrinsically uncertain due to a lot of stochastic characteristics of traffic, especially at signalized intersections. A single travel time does not have much meaning and is not informative to drivers or traffic managers. The range of travel times is large such that certain
The extended (G/G)-expansion method and travelling wave ...
Indian Academy of Sciences (India)
In this paper, we construct the travelling wave solutions to the perturbed nonlinear Schrödinger's equation (NLSE) with Kerr law non-linearity by the extended (′/)-expansion method. Based on this method, we obtain abundant exact travelling wave solutions of NLSE with Kerr law nonlinearity with arbitrary parameters.
Travel personae of American pleasure travelers
DEFF Research Database (Denmark)
Park, S.; Tussyadiah, Iis; Mazanec, J.A.
2010-01-01
Travel style has been shown to be a useful concept for understanding travelers. In this study it is argued that the portfolio of trips (specifically, the portfolio of various trip styles) one takes can be used to describe his/her overall travel persona. Network analysis was used to examine...... personae which, in turn, are related to their choices of places visited and their response to advertising materials. It was concluded that the framework provided by these findings along with new tools on the Internet offer the potential to develop highly personalized communications with existing...
Multimodal Network Equilibrium with Stochastic Travel Times
Directory of Open Access Journals (Sweden)
M. Meng
2014-01-01
Full Text Available The private car, unlike public traffic modes (e.g., subway, trolley running along dedicated track-ways, is invariably subject to various uncertainties resulting in travel time variation. A multimodal network equilibrium model is formulated that explicitly considers stochastic link capacity variability in the road network. The travel time of combined-mode trips is accumulated based on the concept of the mean excess travel time (METT which is a summation of estimated buffer time and tardy time. The problem is characterized by an equivalent VI (variational inequality formulation where the mode choice is expressed in a hierarchical logit structure. Specifically, the supernetwork theory and expansion technique are used herein to represent the multimodal transportation network, which completely represents the combined-mode trips as constituting multiple modes within a trip. The method of successive weighted average is adopted for problem solutions. The model and solution method are further applied to study the trip distribution and METT variations caused by the different levels of the road conditions. Results of numerical examples show that travelers prefer to choose the combined travel mode as road capacity decreases. Travelers with different attitudes towards risk are shown to exhibit significant differences when making travel choice decisions.
International Nuclear Information System (INIS)
Gregg, D.W.; Kidder, R.E.; Biehl, A.T.
1975-01-01
The invention broadly involves a method and means for generating a traveling wave laser pulse and is basically analogous to a single pass light amplifier system. However, the invention provides a traveling wave laser pulse of almost unlimited energy content, wherein a gain medium is pumped in a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)
Stability of cosmological deflagration fronts
Mégevand, Ariel; Membiela, Federico Agustín
2014-05-01
In a cosmological first-order phase transition, bubbles of the stable phase nucleate and expand in the supercooled metastable phase. In many cases, the growth of bubbles reaches a stationary state, with bubble walls propagating as detonations or deflagrations. However, these hydrodynamical solutions may be unstable under corrugation of the interface. Such instability may drastically alter some of the cosmological consequences of the phase transition. Here, we study the hydrodynamical stability of deflagration fronts. We improve upon previous studies by making a more careful and detailed analysis. In particular, we take into account the fact that the equation of motion for the phase interface depends separately on the temperature and fluid velocity on each side of the wall. Fluid variables on each side of the wall are similar for weakly first-order phase transitions, but differ significantly for stronger phase transitions. As a consequence, we find that, for large enough supercooling, any subsonic wall velocity becomes unstable. Moreover, as the velocity approaches the speed of sound, perturbations become unstable on all wavelengths. For smaller supercooling and small wall velocities, our results agree with those of previous works. Essentially, perturbations on large wavelengths are unstable, unless the wall velocity is higher than a critical value. We also find a previously unobserved range of marginally unstable wavelengths. We analyze the dynamical relevance of the instabilities, and we estimate the characteristic time and length scales associated with their growth. We discuss the implications for the electroweak phase transition and its cosmological consequences.
Internal waves and temperature fronts on slopes
Directory of Open Access Journals (Sweden)
S. A. Thorpe
Full Text Available Time series measurements from an array of temperature miniloggers in a line at constant depth along the sloping boundary of a lake are used to describe the `internal surf zone' where internal waves interact with the sloping boundary. More small positive temperature time derivatives are recorded than negative, but there are more large negative values than positive, giving the overall distribution of temperature time derivatives a small negative skewness. This is consistent with the internal wave dynamics; fronts form during the up-slope phase of the motion, bringing cold water up the slope, and the return flow may become unstable, leading to small advecting billows and weak warm fronts. The data are analysed to detect `events', periods in which the temperature derivatives exceed a set threshold. The speed and distance travelled by `events' are described. The motion along the slope may be a consequence of (a instabilities advected by the flow (b internal waves propagating along-slope or (c internal waves approaching the slope from oblique directions. The propagation of several of the observed 'events' can only be explained by (c, evidence that the internal surf zone has some, but possibly not all, the characteristics of the conventional 'surface wave' surf zone, with waves steepening as they approach the slope at oblique angles.
Key words. Oceanography: general (benthic boundary layers; limnology, Oceanography: physical (internal and inertial waves
Travelers' Health: Water Disinfection for Travelers
... Safety Road Safety - 8 Steps MERS Health Advisory poster MERS Pictogram CDC Guide for Healthy Travel Website ... compressed carbon, or large-pore hollow-fiber filter elements are sufficient to remove bacteria and protozoan cysts ...
Greenhouse Earth: A Traveling Exhibition
International Nuclear Information System (INIS)
Booth, W.H.; Caesar, S.
1992-09-01
The Franklin Institute Science Museum provided an exhibit entitled the Greenhouse Earth: A Traveling Exhibition. This 3500 square-foot exhibit on global climate change was developed in collaboration with the Association of Science-Technology Centers. The exhibit opened at The Franklin Institute on February 14, 1992, welcoming 291,000 visitors over its three-month stay. During its three-year tour, Greenhouse Earth will travel to ten US cities, reaching two million visitors. Greenhouse Earth aims to deepen public understanding of the scientific issues of global warming and the conservation measures that can be taken to slow its effects. The exhibit features hands-on exhibitry, interactive computer programs and videos, a theater production, a ''demonstration cart,'' guided tours, and lectures. supplemental educational programs at the Institute included a teachers preview, a symposium on climate change, and a ''satellite field trip.'' The development of Greenhouse Earth included front-end and formative evaluation procedures. Evaluation includes interviews with visitors, prototypes, and summative surveys for participating museums. During its stay in Philadelphia, Greenhouse Earth was covered by the local and national press, with reviews in print and broadcast media. Greenhouse Earth is the first large-scale museum exhibit to address global climate change
Managing Controversies in the Fuzzy Front End
DEFF Research Database (Denmark)
Christiansen, John K.; Gasparin, Marta
2016-01-01
. The analysis investigates the microprocesses around the controversies that emerge during the fuzzy front end of four products. Five different types of controversies are identified: profit, production, design, brand and customers/market. Each controversy represents a threat, but also an opportunity to search...... for new solutions in the unpredictable non-linear processes. The study uses an ethnographic approach using qualitative data from interviews, company documents, external communication and marketing material, minutes of meetings, informal conversations and observations. The analysis of four FFE processes...... demonstrates how the fuzzy front requires managers to deal with controversies that emerge from many different places and involve both human and non-human actors. Closing the controversies requires managers to take account of the situation, identify the problem that needs to be addressed, and initiate a search...
QCD and Light-Front Holography
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.
2010-10-27
The soft-wall AdS/QCD model, modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics. The model predicts a zero-mass pion for zero-mass quarks and a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number N. Light-Front Holography maps the amplitudes which are functions of the fifth dimension variable z of anti-de Sitter space to a corresponding hadron theory quantized on the light front. The resulting Lorentz-invariant relativistic light-front wave equations are functions of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. The result is to a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryon light-quark bound states, which in turn predict the behavior of the pion and nucleon form factors. The theory implements chiral symmetry in a novel way: the effects of chiral symmetry breaking increase as one goes toward large interquark separation, consistent with spectroscopic data, and the the hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. The soft-wall model also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function which agrees with the effective coupling {alpha}{sub g1} extracted from the Bjorken sum rule. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms. A new perspective on quark and gluon condensates is also reviewed.
Topic Map for Authentic Travel
Wandsvik, Atle; Zare, Mehdi
2007-01-01
E-business is a new trend in Internet use. Authentic travel is an approach to travel and travel business which helps the traveler experience what is authentic in the travel destination. But how can the traveler find those small authentic spots and organize them together to compose a vacation? E-business techniques, combined withTopic Maps, can help.
Lee, Vernon J; Wilder-Smith, Annelies
2006-10-01
Singapore has a fast-growing travel industry, but few studies have been done on travel characteristics and travel health practices. This study describes the profile and healthseeking behaviour of travellers attending a travel health clinic in Singapore. A cross-sectional survey was conducted on travellers attending the Traveller's Health and Vaccination Centre (THVC) between September and November 2002 using a standardised questionnaire. Information obtained included individual demographic and medical information, travel patterns, vaccination status and travel health practices. Four hundred and ninetyfive (74%) eligible travellers seen at THVC responded to the questionnaire. Their mean age was 36 years; 77% were professionals, managers, executives, and businessmen, students, and white collar workers. Asia was the main travel destination, and most travelled for leisure and resided in hotels or hostels. The median duration of travel was 16 days. Although >90% had previously travelled overseas, only 20% had previously sought pre-travel advice. Malays were significantly underrepresented (P travel advice compared with Chinese, Indians and Malays. Factors associated with seeking pre-travel advice included travel outside of Asia, especially Africa and South America. Singaporean travellers travel more often to cities rather than rural areas, compared with non-Asian travellers. Asia is the preferred destination, and travel outside of Asia is perceived as more risky and is associated with seeking pre-travel advice and vaccinations. Travel patterns and behaviours need to be taken into account when developing evidence-based travel medicine in Asia.
Bertuzzo, E.; Maritan, A.; Gatto, M.; Rodriguez-Iturbe, I.; Rinaldo, A.
2007-04-01
Moving from a recent quantitative model of the US colonization in the 19th century that relies on analytical and numerical results of reactive-diffusive transport on fractal river networks, this paper considers its generalization to include an embedded flow direction which biases transport. We explore the properties of biased reaction-dispersal models, in which the reaction rates are described by a logistic equation. The relevance of the work is related to the prediction of the role of hydrologic controls on invasion processes (of species, populations, propagules, or infective agents, depending on the specifics of reaction and transport) occurring in river basins. Exact solutions are obtained along with general numerical solutions, which are applied to fractal constructs like Peano basins and real rivers. We also explore similarities and departures from different one-dimensional invasion models where a bias is added to both the diffusion and the telegraph equations, considering their respective ecological insight. We find that the geometrical constraints imposed by the fractal networks imply strong corrections on the speed of traveling fronts that can be enhanced or smoothed by the bias. Applications to real river networks show that the chief morphological parameters affecting the front speed are those characterizing the node-to-node distances measured along the network structure. The spatial density and number of reactive sites thus prove to be a vital hydrologic control on invasions. We argue that our solutions, currently tied to the validity of the logistic growth, might be relevant to the general study of species' spreading along ecological corridors defined by the river network structure.
Active learning of Pareto fronts.
Campigotto, Paolo; Passerini, Andrea; Battiti, Roberto
2014-03-01
This paper introduces the active learning of Pareto fronts (ALP) algorithm, a novel approach to recover the Pareto front of a multiobjective optimization problem. ALP casts the identification of the Pareto front into a supervised machine learning task. This approach enables an analytical model of the Pareto front to be built. The computational effort in generating the supervised information is reduced by an active learning strategy. In particular, the model is learned from a set of informative training objective vectors. The training objective vectors are approximated Pareto-optimal vectors obtained by solving different scalarized problem instances. The experimental results show that ALP achieves an accurate Pareto front approximation with a lower computational effort than state-of-the-art estimation of distribution algorithms and widely known genetic techniques.
Geochemistry of Natural Redox Fronts
International Nuclear Information System (INIS)
Hofmann, B.A.
1999-05-01
Redox fronts are important geochemical boundaries which need to be considered in safety assessment of deep repositories for radioactive waste. In most cases, selected host-rock formations will be reducing due to the presence of ferrous minerals, sulphides, etc. During construction and operation of the repository, air will be introduced into the formation. After repository closure, oxidising conditions may persist locally until all oxygen is consumed. In the case of high-level waste, radiolysis of water may provide an additional source of oxidants. Oxidising conditions within a repository are thus possible and potentially have a strong influence on the mobility of many elements. The rate of movement of redox fronts, the boundary between oxidising and reducing environments, and their influence on migrating radionuclides are thus important factors influencing repository performance. The present report is a review of elemental behaviour at natural redox fronts, based on published information and work of the author. Redox fronts are geochemically and geometrically variable manifestations of a global interface between generally oxidising geochemical milieux in contact with the atmosphere and generally reducing milieux in contact with rocks containing ferrous iron, sulphide and/or organic carbon. A classification of redox fronts based on a subdivision into continental near-surface, marine near-surface, and deep environments is proposed. The global redox interface is often located close to the surface of rocks and sediments and, sometimes, within bodies of water. Temperature conditions are close to ambient. A deeper penetration of the global redox front to depths of several kilometres is found in basins containing oxidised sediments (red beds) and in some hydrothermal circulation systems. Temperatures at such deep redox fronts may reach 200 o C. Both near-surface and deep redox fronts are sites of formation of economic deposits of redox-sensitive elements, particularly of
Travelling Waves in Hyperbolic Chemotaxis Equations
Xue, Chuan; Hwang, Hyung Ju; Painter, Kevin J.; Erban, Radek
2010-01-01
Mathematical models of bacterial populations are often written as systems of partial differential equations for the densities of bacteria and concentrations of extracellular (signal) chemicals. This approach has been employed since the seminal work of Keller and Segel in the 1970s (Keller and Segel, J. Theor. Biol. 30:235-248, 1971). The system has been shown to permit travelling wave solutions which correspond to travelling band formation in bacterial colonies, yet only under specific criteria, such as a singularity in the chemotactic sensitivity function as the signal approaches zero. Such a singularity generates infinite macroscopic velocities which are biologically unrealistic. In this paper, we formulate a model that takes into consideration relevant details of the intracellular processes while avoiding the singularity in the chemotactic sensitivity. We prove the global existence of solutions and then show the existence of travelling wave solutions both numerically and analytically. © 2010 Society for Mathematical Biology.
Travelling Waves in Hyperbolic Chemotaxis Equations
Xue, Chuan
2010-10-16
Mathematical models of bacterial populations are often written as systems of partial differential equations for the densities of bacteria and concentrations of extracellular (signal) chemicals. This approach has been employed since the seminal work of Keller and Segel in the 1970s (Keller and Segel, J. Theor. Biol. 30:235-248, 1971). The system has been shown to permit travelling wave solutions which correspond to travelling band formation in bacterial colonies, yet only under specific criteria, such as a singularity in the chemotactic sensitivity function as the signal approaches zero. Such a singularity generates infinite macroscopic velocities which are biologically unrealistic. In this paper, we formulate a model that takes into consideration relevant details of the intracellular processes while avoiding the singularity in the chemotactic sensitivity. We prove the global existence of solutions and then show the existence of travelling wave solutions both numerically and analytically. © 2010 Society for Mathematical Biology.
Human Resources Division
2002-01-01
Administrative procedures for : Travel to the home station and home leave (hl) Additional travel to the home station (at) Travel to the home station and home leave for family reasons (hlf) As part of the process of simplifying administrative procedures, HR and AS Divisions have devised a new, virtually automatic procedure for payment of travel expenses to the home station. The changes are aimed at rationalising administrative procedures and not at reducing benefits. The conditions of eligibility are unchanged. The new procedure, which will be operational with effect from 1st June 2002, will greatly simplify the administrative processing of claims for travel expenses and the recording of home leaves. Currently, requests for payment are introduced manually into the Advances and Claims system (AVCL) by divisional secretariats. All travel to the home station starting prior to 1st June 2002 will be processed according to the existing system whereas that starting on 1st June and after will be processed accordi...
Moisã Claudia Olimpia; Moisã Claudia Olimpia
2011-01-01
Taking into account the suite of motivation that youth has when practicing tourism, it can be said that the youth travel takes highly diverse forms. These forms are educational tourism, volunteer programs and “work and travel”, cultural exchanges or sports tourism and adventure travel. In this article, we identified and analyzed in detail the main forms of youth travel both internationally and in Romania. We also illustrated for each form of tourism the specific tourism products targeting you...
DEFF Research Database (Denmark)
Helles, Rasmus; Lai, Signe Sophus
2017-01-01
-12) travelling to multiple countries on several continents. The article shows that there are systematic differences in terms of formal characteristics, themes, and characters’ communicative style between the series that travel and the series that do not. Especially, the analysis finds that the presence of strong...... female lead characters is systematically linked to the positive travel patterns of the series, and that this cuts across different genres of series. The analysis also finds that series, which have explicitly low production values and simple narrative structure, systematically travels poorer....
QCD traveling waves beyond leading logarithms
International Nuclear Information System (INIS)
Peschanski, R.; Sapeta, S.
2006-01-01
We derive the asymptotic traveling-wave solutions of the nonlinear 1-dimensional Balitsky-Kovchegov QCD equation for rapidity evolution in momentum space, with 1-loop running coupling constant and equipped with the Balitsky-Kovchegov-Kuraev-Lipatov kernel at next-to-leading logarithmic accuracy, conveniently regularized by different resummation schemes. Traveling waves allow us to define ''universality classes'' of asymptotic solutions, i.e. independent of initial conditions and of the nonlinear damping. A dependence on the resummation scheme remains, which is analyzed in terms of geometric scaling properties
Pre-Travel Medical Preparation of Business and Occupational Travelers
Khan, Nomana M.; Jentes, Emily S.; Brown, Clive; Han, Pauline; Rao, Sowmya R.; Kozarsky, Phyllis; Hagmann, Stefan H.F.; LaRocque, Regina C.; Ryan, Edward T.
2016-01-01
Objectives: The aim of the study was to understand more about pre-travel preparations and itineraries of business and occupational travelers. Methods: De-identified data from 18 Global TravEpiNet clinics from January 2009 to December 2012 were analyzed. Results: Of 23,534 travelers, 61% were non-occupational and 39% occupational. Business travelers were more likely to be men, had short times to departure and shorter trip durations, and commonly refused influenza, meningococcal, and hepatitis B vaccines. Most business travelers indicated that employers suggested the pre-travel health consultation, whereas non-occupational travelers sought consultations because of travel health concerns. Conclusions: Sub-groups of occupational travelers have characteristic profiles, with business travelers being particularly distinct. Employers play a role in encouraging business travelers to seek pre-travel consultations. Such consultations, even if scheduled immediately before travel, can identify vaccination gaps and increase coverage. PMID:26479857
Carlson Wagonlit Travel
2005-01-01
Chères clientes, chers clients, Le 3 janvier dernier, nous vous avons informé de la décision des compagnies aériennes de supprimer les commissions versées aux agences de voyages suisses. Cette mesure a été introduite progressivement pour être appliquées maintenant par toutes les compagnies, à quelques rares exceptions près. En conséquence, en accord avec le CERN, nous serons dans l'obligation d'appliquer une nouvelle liste de prix de nos transactions pour les voyages privés. Elle sera applicable dès le lundi 25 juillet 2005. Carlson Wagonlit Travel (CWT) vous propose : Son service de conseil personnalisé, professionnel et compétent Sa recherche de la solution la plus économique et la mieux adaptée à vos besoins Sa neutralité dans les comparaisons de prix et prestations Des informations com...
Overtopping of Rubble Mound Breakwaters with Front Reservoir
DEFF Research Database (Denmark)
Burcharth, Hans F.; Andersen, Thomas Lykke
2007-01-01
The design and performance of breakwaters with front reservoir are discussed on the basis of physical 2-D model tests with a number of cross sections, in which vertopping discharge and spatial distribution, wave forces on inner parapet walls, and stability of reservoir armour were studied....... The sensitivity of these quantities to the width of the reservoir is discussed. It is demonstrated that front reservoir solutions are more economical than conventional cross section solutions, such as bermed structures and mild slope structures, in cases where low crests and small overtopping discharges...
"Front" hotshet izvinitsja / Aleksandr Ikonnikov
Ikonnikov, Aleksandr
2003-01-01
Põhiliselt vene rahvusest noori ühendava liikumise "Front" esindajad kavatsevad kohtuda USA suursaadikuga Eestis ja vabandada kevadel suursaatkonna ees vägivallatsemisega lõppenud meeleavalduse pärast
Energy conversion at dipolarization fronts
Khotyaintsev, Yu. V.; Divin, A.; Vaivads, A.; André, M.; Markidis, S.
2017-02-01
We use multispacecraft observations by Cluster in the Earth's magnetotail and 3-D particle-in-cell simulations to investigate conversion of electromagnetic energy at the front of a fast plasma jet. We find that the major energy conversion is happening in the Earth (laboratory) frame, where the electromagnetic energy is being transferred from the electromagnetic field to particles. This process operates in a region with size of the order several ion inertial lengths across the jet front, and the primary contribution to E·j is coming from the motional electric field and the ion current. In the frame of the front we find fluctuating energy conversion with localized loads and generators at sub-ion scales which are primarily related to the lower hybrid drift instability excited at the front; however, these provide relatively small net energy conversion.
Advanced Traveler Information Systems (ATIS) 2.0 Precursor System: Final Report
2018-03-01
Advanced Traveler Information Systems (ATIS) have experienced significant growth since their initial inception in the 1990s. Technologies have continued to evolve at a rapid pace, enabling the integration of advanced solutions for traveler informatio...
2006-01-01
CARLSON WAGONLIT TRAVEL informs you that our agency will be closed from 22 December 2006 at 16:30 until 8 January 2007 at 8:30. For all URGENT MATTERS you can contact our CARLSON WAGONLIT TRAVEL branch at W.H.O. (Mr Pierre Plumettaz), phone: 022 791 55 95. We wish you already a Merry Christmas and a Happy New Year!
CARLSON WAGONLIT TRAVEL
2004-01-01
CARLSON WAGONLIT TRAVEL informs you that our agency will be closed from 17 December 2004 at 16:30 until 3 January 2005 at 8:30. For all URGENT MATTERS you can contact our CARLSON WAGONLIT TRAVEL branch at WHO (Mr Pierre Plumettaz), phone: 022 788 10 65 We wish you already a Merry Christmas and a Happy New Year!
2016-08-01
Knowingly or not, people generally place economic value on their time. Wage workers are paid a rate per hour, and service providers may charge per hour of their time. In the transportation realm, travelers place a value on their travel time and have ...
Korzeniewski, Krzysztof
All around the world there has been a rapid growth in the number of international travels. According to the World Tourism Organisation the number of international tourist arrivals reached 1,235 billion in 2016 and continues to grow at a high rate. This has been much due to the development of air transport (including low-cost airlines), increasingly common economic migration, a growing number of travellers visiting friends and relatives, and an increase in medical tourism. With tropical destinations becoming increasingly popular among travellers, doctors have seen a rising number of patients who seek medical advice on health risks prevalent in hot countries and health prevention measures to be taken in tropical destinations, especially where sanitation is poor. The risk for developing a medical condition while staying abroad depends on a variety of factors, including the traveller's general health condition, health prevention measures taken before or during travel (vaccinations, antimalarial chemoprophylaxis, health precautions during air, road and sea travel, proper acclimatisation, prevention of heat injuries, protection against local flora and fauna, personal hygiene, water, food and feeding hygiene), as well as the prevalence of health risk factors in a given location. Health prevention is a precondition for safe travel and maintaining good physical health; in the era of a rapid growth in international tourism it has become of key importance for all travellers.
DEFF Research Database (Denmark)
Bill, Jan; Roesdahl, Else
2007-01-01
On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport; on the related technologies and their developments......On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport; on the related technologies and their developments...
Travel/Travelers and Parasitic Diseases
... of the world and specific country. Many infectious diseases transmitted in food and water can also be acquired directly through the fecal-oral route. Parasitic Illnesses That Can Be Acquired During Travel* From Contaminated Food and Water More ... filariasis African sleeping sickness Onchoceriasis *This list ...
Travel Software using GPU Hardware
Szalwinski, Chris M; Dimov, Veliko Atanasov; CERN. Geneva. ATS Department
2015-01-01
Travel is the main multi-particle tracking code being used at CERN for the beam dynamics calculations through hadron and ion linear accelerators. It uses two routines for the calculation of space charge forces, namely, rings of charges and point-to-point. This report presents the studies to improve the performance of Travel using GPU hardware. The studies showed that the performance of Travel with the point-to-point simulations of space-charge effects can be speeded up at least 72 times using current GPU hardware. Simple recompilation of the source code using an Intel compiler can improve performance at least 4 times without GPU support. The limited memory of the GPU is the bottleneck. Two algorithms were investigated on this point: repeated computation and tiling. The repeating computation algorithm is simpler and is the currently recommended solution. The tiling algorithm was more complicated and degraded performance. Both build and test instructions for the parallelized version of the software are inclu...
NADIM-Travel: A Multiagent Platform for Travel Services Aggregation
Ben Ameur, Houssein; Bédard, François; Vaucher, Stéphane; Kropf, Peter; Chaib-draaa, Brahim; Gérin-Lajoie, Robert
2010-01-01
With the Internet as a growing channel for travel services distribution, sophisticated travel services aggregators are increasingly in demand. A travel services aggregation platform should be able to manage the heterogeneous characteristics of the many existing travel services. It should also be as scalable, robust, and flexible as possible. Using multiagent technology, we designed and implemented a multiagent platform for travel services aggregation called NADIM-Travel. In this platform, a p...
Travel time data collection handbook
1998-03-01
This Travel Time Data Collection Handbook provides guidance to transportation : professionals and practitioners for the collection, reduction, and presentation : of travel time data. The handbook should be a useful reference for designing : travel ti...
On the propagation of a coupled saturation and pressure front
Energy Technology Data Exchange (ETDEWEB)
Vasco, D. W.
2010-12-01
Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The propagation of the two-phase front is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a pressure-dominated disturbance that travels through the saturated layer. This is followed, much later, by a coupled mode with a large saturation change. These two modes are also observed in a simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.
Intercity Travel Demand Analysis Model
Ming Lu; Hai Zhu; Xia Luo; Lei Lei
2014-01-01
It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model...
Travelers' Health: Motion Sickness
... sickness, especially when pregnant, menstruating, or on hormones. Race/ethnicity—Asians may be more susceptible to motion ... it, sitting in the front seat of a car or bus, sitting over the wing of an ...
Zero modes in discretized light-front quantization
International Nuclear Information System (INIS)
Martinovic, E.
1997-01-01
The current understanding of the role of bosonic zero modes in field-theoretical models quantized at the equal light-front time is reviewed. After a brief discussion of the main features of the light-front field theories - in particular the simplicity of the physical vacuum - the light-front canonical formalism for the quantum electrodynamics and the Yukawa model is sketched. The zero mode of Maskawa and Yamawaki is reviewed. Reasons for the appearance of the constrained and/or dynamical zero modes are explained along with the subtleties of the gauge fixing in presence of boundary conditions. Perturbative treatment of the corresponding constraint equations in the Yukawa model and quantum electrodynamics (3+1) is outlined. The next topic is the manifestation of the symmetry breaking in the light-front field theory. A pattern of multiple solutions to the zero-mode constraint equations replacing physical picture of multiple vacua of the conventionally quantized field theories is illustrated on an example of 2-dimensional theory. The importance of a (regularized) constrained zero mode of the pion field for the consistency of the Nambu-Goldstone phase of the discretized light-front linear a/model is demonstrated. Finally, a non-trivial physical vacuum based on the dynamical zero mode is constructed for the two-dimensional light-front quantum electrodynamics. (authors)
Optimal Design of HGV Front Structure for Pedestrian Safety
Ramli, Faiz Redza; Yamazaki, Koetsu
This paper addresses a pedestrian safety design of front structure of Heavy Goods Vehicle (HGV) by two concepts; firstly by equipping a lower bumper stiffener structure under the front bumper and secondly by putting an airbag in front of the HGV front panel. In this study, HGV-pedestrian collision accident was simulated by the crash analysis solver MADYMO environment, where the HGV model with the speed of 20 km/h was collided with an adult male and with an adult female pedestrian, respectively. The bumper and lower bumper stiffener were varied their positions, while the airbag was adjusted the vent hole size and the position of airbag in front of front panel vertically. The pedestrian injuries that can be sustained during the simulation impact were limited at the critical body parts of head, chest, upper leg; an injury criteria of Head Injury Criterion (HIC), Thorax Cumulative 3ms Acceleration (C3ms) and peak loads of femur, respectively. Because of various parameters and constraints of initial conditions and injury thresholds, a multi-objective optimization design problem considered these main injury criterion is solved in order to achieve the best solution for this study. The results of optimized design parameters for each cases and conditions were obtained and the possibilities of the proposed concept were discussed.
Travelers' Health: Meningococcal Disease
... Zika Travel Information World Map of Zika Country Classification Technical Guidance Risk of Zika Virus at Your ... Meningococcal meningitis is characterized by sudden onset of headache, fever, and stiffness of the neck, sometimes accompanied ...
... 36 weeks of pregnancy. Some domestic airlines restrict travel completely or require a medical certificate during the last month of pregnancy. For international flights, the cutoff point often is earlier, sometimes as early as 28 ...
Avoid bringing bed bugs home by taking precautions when traveling such as inspecting bedding and luggage racks in hotel rooms, and upon returning home unpacking directly into a washing machine and dry at high temperatures.
When traveling by land: You should be on the road no more than 5 to 6 hours a day. Always wear your seatbelt. ... of fluids. Women with health problems may need extra oxygen when flying. Talk to your provider before ...
Caregiving and travel patterns.
2013-06-01
This study explored the impact of caregiving for older adults on mobility and travel : patterns. Specifically, the focus was on how caregivers managed trips on behalf of : another who receives care. Caregiving is becoming increasingly common as the :...
Centers for Disease Control (CDC) Podcasts
Malaria is a serious mosquito-borne disease that can lead to death. This podcast discusses malaria risk when traveling to tropical areas, as well as how to protect yourself and your family from malaria infection.
Hietala, V.M.; Vawter, G.A.
1993-12-14
The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size. 4 figures.
... Providers, Emergency Consultations, and General Public. Contact Us Malaria and Travelers for U.S. Residents Recommend on Facebook ... may be at risk for infection. Determine if malaria transmission occurs at the destinations Obtain a detailed ...
... Books, Journals, Articles & Websites Resources for the Travel Industry Yellow Book Contents Chapter 3 (83) Scabies more ... have crusted scabies. Contact with items such as clothing and bed linens that have been used by ...
Illinois travel statistics, 2008
2009-01-01
The 2008 Illinois Travel Statistics publication is assembled to provide detailed traffic : information to the different users of traffic data. While most users of traffic data at this level : of detail are within the Illinois Department of Transporta...
Illinois travel statistics, 2009
2010-01-01
The 2009 Illinois Travel Statistics publication is assembled to provide detailed traffic : information to the different users of traffic data. While most users of traffic data at this level : of detail are within the Illinois Department of Transporta...
Illinois travel statistics, 2010
2011-01-01
The 2010 Illinois Travel Statistics publication is assembled to provide detailed traffic : information to the different users of traffic data. While most users of traffic data at this level : of detail are within the Illinois Department of Transporta...
Travelling with football teams
African Journals Online (AJOL)
ultimately on the performance of the teams on the playing field and not so much ... However, travelling with a football team presents the team physician .... physician to determine the nutritional ..... diarrhoea in elite athletes: an audit of one team.
Travelers' Health: Cryptosporidiosis
... associated diarrhea; cryptosporidiosis was associated with travel to Asia, particularly India, and Latin America. Another study found ... immunochromatographic cartridge assays, and microscopy with modified acid-fast staining. ... and water precautions (see Chapter 2, Food & Water ...
Business travel and sustainability
AGUILERA, Anne
2013-01-01
Although it contributes significantly to the demand for transport, in particular air transport, business travel has been relatively neglected in thinking about the strategies needed to promote more sustainable mobility practices. This paper provides a two-stage approach to this subject. We begin by showing how the sustainability of business travel is relevant not only in environmental terms, but also from an economic and social perspective. In the second stage, we consider the strategies that...
Travel Market Switzerland 2007
Laesser, Christian; Bieger, Thomas
2008-01-01
Technical Report and Results - In 2007, for the seventeenth time since 1972, a survey on the travel behaviour of the Swiss population was conducted. The database resulting from this project (Travel Market Switzerland 2007) is still the most extensive on private trips by the Swiss resident population. Private trips are defined/ delimited as all journeys by private persons with at least one overnight stay outside their home and their normal life and work environment. They include all types of l...
Barrett-Connor, Elizabeth
1975-01-01
Travelers, particularly those whose tastes or occupations lead to deviation from the usual tourist routes, are at a small but significant risk of acquiring certain diseases they would be unlikely to encounter had they remained in the continental United States. Many of these infections can be rendered unlikely even for the most adventuresome traveler through the appropriate use of immunization and chemoprophylaxis. Other infections are currently unpreventable and the physician's responsibility lies in their premorbid detection. PMID:1154779
The New England travel market: changes in generational travel patterns
Rodney B. Warnick
1995-01-01
The purpose of this study was to examine and explore the New England domestic travel market trends, from 1979 through 1991 within the context of generations. The existing travel markets, who travel to New England, are changing by age cohorts and specifically within different generations. The New England changes in generational travel patterns do not reflect national...
Front lighted optical tooling method and apparatus
International Nuclear Information System (INIS)
Stone, W. J.
1985-01-01
An optical tooling method and apparatus uses a front lighted shadowgraphic technique to enhance visual contrast of reflected light. The apparatus includes an optical assembly including a fiducial mark, such as cross hairs, reflecting polarized light with a first polarization, a polarizing element backing the fiducial mark and a reflective surface backing the polarizing element for reflecting polarized light bypassing the fiducial mark and traveling through the polarizing element. The light reflected by the reflecting surface is directed through a second pass of the polarizing element toward the frontal direction with a polarization differing from the polarization of the light reflected by the fiducial mark. When used as a tooling target, the optical assembly may be mounted directly to a reference surface or may be secured in a mounting, such as a magnetic mounting. The optical assembly may also be mounted in a plane defining structure and used as a spherometer in conjunction with an optical depth measuring instrument. A method of measuring a radius of curvature of an unknown surface includes positioning the spherometer on a surface between the surface and a depth measuring optical instrument. As the spherometer is frontally illuminated, the distance from the depth measuring instrument to the fiducial mark and the underlying surface are alternately measured and the difference in these measurements is used as the sagittal height to calculate a radius of curvature
Travels in Architectural History
Directory of Open Access Journals (Sweden)
Davide Deriu
2016-11-01
Full Text Available Travel is a powerful force in shaping the perception of the modern world and plays an ever-growing role within architectural and urban cultures. Inextricably linked to political and ideological issues, travel redefines places and landscapes through new transport infrastructures and buildings. Architecture, in turn, is reconstructed through visual and textual narratives produced by scores of modern travellers — including writers and artists along with architects themselves. In the age of the camera, travel is bound up with new kinds of imaginaries; private records and recollections often mingle with official, stereotyped views, as the value of architectural heritage increasingly rests on the mechanical reproduction of its images. Whilst students often learn about architectural history through image collections, the place of the journey in the formation of the architect itself shifts. No longer a lone and passionate antiquarian or an itinerant designer, the modern architect eagerly hops on buses, trains, and planes in pursuit of personal as well as professional interests. Increasingly built on a presumption of mobility, architectural culture integrates travel into cultural debates and design experiments. By addressing such issues from a variety of perspectives, this collection, a special 'Architectural Histories' issue on travel, prompts us to rethink the mobile conditions in which architecture has historically been produced and received.
Simşekoğlu, Ozlem; Lajunen, Timo
2008-01-01
Low seat belt use rate among car occupants is one of the main problems contributing to low driver and passenger safety in Turkey, where injury and fatality rates of car occupants are very high in traffic crashes. The present article consists of two observation studies, which were conducted in Ankara. The first study aimed at investigating environmental factors and occupant characteristics affecting seat belt use among front-seat occupants, and the objective of the second study was to investigate the relationship between driver and front-seat passenger seat belt use. In the first study, 4, 227 front-seat occupants (drivers or front seat passengers) were observed on four different road sides and, in the second study 1, 398 front seat occupants were observed in car parks of five different shopping centers in Ankara. In both observations, front-seat occupants' seat bet use (yes, no), sex (male, female), and age ( 50 years) were recorded. The data were analyzed using chi-square statistics and binary logistic regression techniques. Results of the first study showed that seat belt use proportion among observed front seat occupants was very low (25%). Being female and traveling on intercity roads were two main factors positively related to use a seat belt among front-seat occupants. High correlations between seat belt use of the drivers and front-seat passengers were found in the second study. Overall, low seat belt use rate (25%) among the front-seat occupants should be increased urgently for an improved driver and passenger safety in Turkey. Seat belt campaigns especially tailored for male front-seat occupants and for the front-seat occupants traveling on city roads are needed to increase seat belt use rates among them. Also, both drivers and passengers may have an important role in enforcing seat belt use among themselves.
Multiple stable isotope fronts during non-isothermal fluid flow
Fekete, Szandra; Weis, Philipp; Scott, Samuel; Driesner, Thomas
2018-02-01
develop in kinetically limited systems, which propagates with the advection speed of the incoming fluid and is, therefore, traveling fastest. The results show that oxygen isotope signatures at thermal fronts recorded in rocks and veins that experienced isotope exchange with fluids can easily be misinterpreted, namely if bulk analytical techniques are applied. However, stable isotope microanalysis on precipitated minerals may - if later isotope exchange is kinetically limited - provide a valuable archive of the transient thermal and hydrological evolution of a system.
Perry, Jim
1995-01-01
Discussion of management styles and front-end analysis focuses on a review of Douglas McGregor's theories. Topics include Theories X, Y, and Z; leadership skills; motivational needs of employees; intrinsic and extrinsic rewards; and faulty implementation of instructional systems design processes. (LRW)
Virtual Travel Agencies - Tourist Value through Travel Information Systems
Anckar, Bill
1999-01-01
Anckar, B. (1999), ?Virtual Travel Agencies - Tourist Value through Travel Information Systems?. IAMSR Research Report 5/99. Institute for Advanced Management Systems Research, ?bo Akademi University. As electronic commerce enables the tourist service providers to sell their products directly to the consumer, travel agencies are faced with the imminent threat of being by-passed in the travel industry chain in the information age. This paper suggests that virtual travel agencies can compete su...
Hepatitis B vaccination in travelers
Sonder, Gerard J. B.
2008-01-01
An increasing number of travelers travel to hepatitis B-endemic countries. In travel medicine, vaccinations should be advised according to risks. The actual incidence of hepatitis B infection in short-term tourists is very low and probably not higher than it is for people who do not travel. There is
Travel health attitudes among Turkish business travellers to African countries.
Selcuk, Engin Burak; Kayabas, Uner; Binbasioglu, Hulisi; Otlu, Baris; Bayindir, Yasar; Bozdogan, Bulent; Karatas, Mehmet
The number of international travellers is increasing worldwide. Although health risks related to international travel are important and generally well-understood, the perception of these risks was unclear among Turkish travellers. We aimed to evaluate the attitudes and health risk awareness of Turkish travellers travelling to African countries. A survey was performed of Turkish travellers bound for Africa from Istanbul International Ataturk Airport in July 2013. A total of 124 travellers were enrolled in the study. Among them, 62.9% had information about their destination but only 11.3% had looked for information on health problems related to travel and their destination. Of all travellers, 53.2% had at least one vaccination before travelling. The most commonly administered vaccine was for typhoid. Among the travellers, 69.3% and 80.6% had "no idea" about yellow fever vaccination and malaria prophylaxis, respectively. A positive correlation was found between a higher level of travellers' education and receiving the recommended vaccination for the destination. Our study revealed significant gaps in the vaccination and chemoprophylaxis uptake of Turkish travellers departing to Africa. An awareness and training program should be developed for travellers, as well as public health workers, to address health risks related to travel. Copyright © 2016 Elsevier Ltd. All rights reserved.
Leggat, Peter A; Zwar, Nicholas; Hudson, Bernie
2012-09-01
The Travel Health Advisory Group (THAG), established in 1997, is a joint initiative between the travel industry and travel health professionals in Australia that aims to promote healthy travel. THAG seeks to promote cooperation in improving the health of travellers between the travel industry and travel medicine professionals and to raise public awareness of the importance of travel health. From 2011, THAG has been a Special Interest Group of The Australasian College of Tropical Medicine and its membership has been active in several areas, including web-based travel health information, travel health promotion, media releases, research and education in Australia. Information is given on the objectives, membership and an overview of the various activities of the group. Copyright © 2012 Elsevier Ltd. All rights reserved.
Existence, uniqueness, monotonicity and asymptotic behaviour of travelling waves for epidemic models
International Nuclear Information System (INIS)
Hsu, Cheng-Hsiung; Yang, Tzi-Sheng
2013-01-01
The purpose of this work is to investigate the existence, uniqueness, monotonicity and asymptotic behaviour of travelling wave solutions for a general epidemic model arising from the spread of an epidemic by oral–faecal transmission. First, we apply Schauder's fixed point theorem combining with a supersolution and subsolution pair to derive the existence of positive monotone monostable travelling wave solutions. Then, applying the Ikehara's theorem, we determine the exponential rates of travelling wave solutions which converge to two different equilibria as the moving coordinate tends to positive infinity and negative infinity, respectively. Finally, using the sliding method, we prove the uniqueness result provided the travelling wave solutions satisfy some boundedness conditions. (paper)
Travelers' Health: Trypanosomiasis, American (Chagas Disease)
... Stamaril clinics Disease Directory Resources Resources for Travelers Adventure Travel Animal Safety Blood Clots Bug Bites Evite ... Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ...
Persistence of travelling waves in a generalized Fisher equation
International Nuclear Information System (INIS)
Kyrychko, Yuliya N.; Blyuss, Konstantin B.
2009-01-01
Travelling waves of the Fisher equation with arbitrary power of nonlinearity are studied in the presence of long-range diffusion. Using analogy between travelling waves and heteroclinic solutions of corresponding ODEs, we employ the geometric singular perturbation theory to prove the persistence of these waves when the influence of long-range effects is small. When the long-range diffusion coefficient becomes larger, the behaviour of travelling waves can only be studied numerically. In this case we find that starting with some values, solutions of the model lose monotonicity and become oscillatory
Travel Time Reliability in Indiana
Martchouk, Maria; Mannering, Fred L.; Singh, Lakhwinder
2010-01-01
Travel time and travel time reliability are important performance measures for assessing traffic condition and extent of congestion on a roadway. This study first uses a floating car technique to assess travel time and travel time reliability on a number of Indiana highways. Then the study goes on to describe the use of Bluetooth technology to collect real travel time data on a freeway and applies it to obtain two weeks of data on Interstate 69 in Indianapolis. An autoregressive model, estima...
Nefedov, Nikolay
2017-02-01
This is an extended variant of the paper presented at MURPHYS-HSFS 2016 conference in Barcelona. We discuss further development of the asymptotic method of differential inequalities to investigate existence and stability of sharp internal layers (fronts) for nonlinear singularly perturbed periodic parabolic problems and initial boundary value problems with blow-up of fronts for reaction-diffusion-advection equations. In particular, we consider periodic solutions with internal layer in the case of balanced reaction. For the initial boundary value problems we prove the existence of fronts and give their asymptotic approximation including the new case of blowing-up fronts. This case we illustrate by the generalised Burgers equation.
Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.
2012-02-16
momentum distributions. The effective confining potential also creates quark-antiquark pairs from the amplitude q {yields} q{bar q}q. Thus in holographic QCD higher Fock states can have any number of extra q{bar q} pairs. We discuss the relevance of higher Fock-states for describing the detailed structure of space and time-like form factors. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms. A new perspective on quark and gluon condensates is also obtained.
Travel-related health problems in Japanese travelers.
Mizuno, Yasutaka; Kudo, Koichiro
2009-09-01
Although the number of Japanese individuals traveling abroad has increased steadily, reaching approximately 17.3 million in 2007, the incidence of various travel-related health problems in Japan remains unknown. The travel-related health problems of Japanese travelers returning to Japan from abroad are analyzed by assessing the records. Data were collected retrospectively on returning travelers who visited the authors' travel clinic during the period from January 2005 through to December 2006 with any health problem acquired overseas. A total of 345 patients were included in this study (200 male, 145 female; average age, 34+/-12.3 years). Reasons for travel included leisure (45.8%); business (39.1%); visiting friends and relatives or accompanying other travelers (8.7%); volunteering (3.8%); and long stays in order to study or live (2.6%). The most visited destination was Asia (n=260), followed by Africa (n=105). The most commonly reported health problems were gastro-intestinal infections (39.1%), followed by respiratory tract infections (16.2%), animal bites (8.1%), and skin problems (5.8%). Together, malaria and dengue accounted for 10% of diagnoses in 125 febrile patients (36.2%). Although the profile of travel-related health problems in Japanese travelers is similar to that of Western travelers, the characteristics of travel were quite different. Therefore Japanese travel advice should be tailored to suit the Japanese traveler.
Methods for enhancing mapping of thermal fronts in oil recovery
Lee, D.O.; Montoya, P.C.; Wayland, J.R. Jr.
1984-03-30
A method for enhancing the resistivity contrasts of a thermal front in an oil recovery production field as measured by the controlled source audio frequency magnetotelluric (CSAMT) technique is disclosed. This method includes the steps of: (1) preparing a CSAMT-determined topological resistivity map of the production field; (2) introducing a solution of a dopant material into the production field at a concentration effective to alter the resistivity associated with the thermal front; said dopant material having a high cation exchange capacity which might be selected from the group consisting of montmorillonite, illite, and chlorite clays; said material being soluble in the conate water of the production field; (3) preparing a CSAMT-determined topological resistivity map of the production field while said dopant material is moving therethrough; and (4) mathematically comparing the maps from step (1) and step (3) to determine the location of the thermal front. This method is effective with the steam flood, fire flood and water flood techniques.
Schistosomiasis and international travel.
Corachan, Manuel
2002-08-15
Infection with Schistosoma species is acquired by exposure to fresh water that harbors cercariae released by infected snails. Although the route of infection is clear, clinical presentation of the established infection in the nonimmune tourist typically differs from that in the local population of areas of endemicity. For the health care practitioner, the traveler's syndrome presents distinctive management problems: water-transmitted bacterial and viral infections may coexist, and identification of the stage of disease at presentation, along with identification of the causative species, will maximize treatment options. Travel medicine clinics serve as epidemiological antennae, helping to identify the dynamics of species transmission in geographically distinct areas. Education of persons traveling to areas of endemicity and the development of mechanical protection against exposure are needed.
[Viral hepatitis in travellers].
Abreu, Cândida
2007-01-01
Considering the geographical asymmetric distribution of viral hepatitis A, B and E, having a much higher prevalence in the less developed world, travellers from developed countries are exposed to a considerable and often underestimated risk of hepatitis infection. In fact a significant percentage of viral hepatitis occurring in developed countries is travel related. This results from globalization and increased mobility from tourism, international work, humanitarian and religious missions or other travel related activities. Several studies published in Europe and North America shown that more than 50% of reported cases of hepatitis A are travel related. On the other hand frequent outbreaks of hepatitis A and E in specific geographic areas raise the risk of infection in these restricted zones and that should be clearly identified. Selected aspects related with the distribution of hepatitis A, B and E are reviewed, particularly the situation in Portugal according to the published studies, as well as relevant clinical manifestations and differential diagnosis of viral hepatitis. Basic prevention rules considering enteric transmitted hepatitis (hepatitis A and hepatitis E) and parenteral transmitted (hepatitis B) are reviewed as well as hepatitis A and B immunoprophylaxis. Common clinical situations and daily practice "pre travel" advice issues are discussed according to WHO/CDC recommendations and the Portuguese National Vaccination Program. Implications from near future availability of a hepatitis E vaccine, a currently in phase 2 trial, are highlighted. Potential indications for travellers to endemic countries like India, Nepal and some regions of China, where up to 30% of sporadic cases of acute viral hepatitis are caused by hepatitis E virus, are considered. Continued epidemiological surveillance for viral hepatitis is essential to recognize and control possible outbreaks, but also to identify new viral hepatitis agents that may emerge as important global health
2008-01-01
We would like to inform you that our agency will be closed from 21st December 2008 at 16:30 until 5th January 2009 at 8:30. For all URGENT MATTERS you can contact our CARLSON WAGONLIT TRAVEL at Rue du Nant in Geneva (Team 3), phone: 058 322 26 20. The agency will be open on 22nd, 23rd, 29th and 30th December. We wish you a Merry Christmas and a Happy New Year! CARLSON WAGONLIT TRAVEL CERN Agency
Koski, Olivia; Rosin, Mark; Guerilla Science Team
2014-03-01
The Intergalactic Travel Bureau is an interactive theater outreach experience that engages the public in the incredible possibilities of space tourism. The Bureau is staffed by professional actors, who play the role of space travel agents, and professional astrophysicists, who play the role of resident scientists. Members of the public of all ages were invited to visit with bureau staff to plan the vacation of their dreams-to space. We describe the project's successful nine day run in New York in August 2013. Funded by the American Physical Society Public Outreach and Informing the Public Grants.
DEFF Research Database (Denmark)
Kroløkke, Charlotte
2015-01-01
Feminist scholars have critically questioned the practices and ethics of reproductive mobility. While the reproductive mobility of fertility patients has been foregrounded, little is known of egg donor mobility including the experiences of travelling internationally to donate eggs. Based on written...... stories and photographic material provided by forty-two egg donors, this article uses feminist cluster analysis and the concept of eggpreneurship to illustrate how global egg donors negotiate reproductive agency and choice when they travel internationally to donate their eggs. In their stories, global egg...
Adaptive two-regime method: Application to front propagation
Energy Technology Data Exchange (ETDEWEB)
Robinson, Martin, E-mail: martin.robinson@maths.ox.ac.uk; Erban, Radek, E-mail: erban@maths.ox.ac.uk [Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford OX2 6GG (United Kingdom); Flegg, Mark, E-mail: mark.flegg@monash.edu [School of Mathematical Sciences, Faculty of Science, Monash University Wellington Road, Clayton, Victoria 3800 (Australia)
2014-03-28
The Adaptive Two-Regime Method (ATRM) is developed for hybrid (multiscale) stochastic simulation of reaction-diffusion problems. It efficiently couples detailed Brownian dynamics simulations with coarser lattice-based models. The ATRM is a generalization of the previously developed Two-Regime Method [Flegg et al., J. R. Soc., Interface 9, 859 (2012)] to multiscale problems which require a dynamic selection of regions where detailed Brownian dynamics simulation is used. Typical applications include a front propagation or spatio-temporal oscillations. In this paper, the ATRM is used for an in-depth study of front propagation in a stochastic reaction-diffusion system which has its mean-field model given in terms of the Fisher equation [R. Fisher, Ann. Eugen. 7, 355 (1937)]. It exhibits a travelling reaction front which is sensitive to stochastic fluctuations at the leading edge of the wavefront. Previous studies into stochastic effects on the Fisher wave propagation speed have focused on lattice-based models, but there has been limited progress using off-lattice (Brownian dynamics) models, which suffer due to their high computational cost, particularly at the high molecular numbers that are necessary to approach the Fisher mean-field model. By modelling only the wavefront itself with the off-lattice model, it is shown that the ATRM leads to the same Fisher wave results as purely off-lattice models, but at a fraction of the computational cost. The error analysis of the ATRM is also presented for a morphogen gradient model.
Light front quantum chromodynamics: Towards phenomenology
Indian Academy of Sciences (India)
Light front dynamics; quantum chromodynamics; deep inelastic scattering. PACS Nos 11.10. ... What makes light front dynamics appealing from high energy phenomenology point of view? .... given in terms of Poincarй generators by. MВ = W P ...
Front Propagation in Stochastic Neural Fields
Bressloff, Paul C.; Webber, Matthew A.
2012-01-01
We analyze the effects of extrinsic multiplicative noise on front propagation in a scalar neural field with excitatory connections. Using a separation of time scales, we represent the fluctuating front in terms of a diffusive-like displacement
Traveling waves of the regularized short pulse equation
International Nuclear Information System (INIS)
Shen, Y; Horikis, T P; Kevrekidis, P G; Frantzeskakis, D J
2014-01-01
The properties of the so-called regularized short pulse equation (RSPE) are explored with a particular focus on the traveling wave solutions of this model. We theoretically analyze and numerically evolve two sets of such solutions. First, using a fixed point iteration scheme, we numerically integrate the equation to find solitary waves. It is found that these solutions are well approximated by a finite sum of hyperbolic secants powers. The dependence of the soliton's parameters (height, width, etc) to the parameters of the equation is also investigated. Second, by developing a multiple scale reduction of the RSPE to the nonlinear Schrödinger equation, we are able to construct (both standing and traveling) envelope wave breather type solutions of the former, based on the solitary wave structures of the latter. Both the regular and the breathing traveling wave solutions identified are found to be robust and should thus be amenable to observations in the form of few optical cycle pulses. (paper)
Seabirds and fronts: a brief overview
Schneider, David C.
1990-01-01
Oceanographic fronts are the sites of enhanced physical and biological activity, including locally concentrated feeding by marine birds. Two general hypotheses relating marine birds to fronts have been developed. The first is that enhanced primary production at fronts increases prey supply through increased animal growth, reproduction, or immigration. The second is that prey patches develop at fronts either through behavioural responses of prey to thermal or salinity gradients, or through int...
Fluctuation charge effects in ionization fronts
International Nuclear Information System (INIS)
Arrayas, Manuel; Trueba, Jose L; Baltanas, J P
2008-01-01
In this paper, we study the effects of charge fluctuations on the propagation of both negative and positive ionization fronts in streamer discharges. We show that fronts accelerate when random charge creation events are present. This effect might play a similar role to photoionization in order to make the front move faster
Fluctuation charge effects in ionization fronts
Energy Technology Data Exchange (ETDEWEB)
Arrayas, Manuel; Trueba, Jose L [Area de Electromagnetismo, Universidad Rey Juan Carlos, Camino del Molino s/n, 28943 Fuenlabrada, Madrid (Spain); Baltanas, J P [Departamento de Fisica Aplicada II, Universidad de Sevilla, Av. Reina Mercedes 2, 41012 Sevilla (Spain)
2008-05-21
In this paper, we study the effects of charge fluctuations on the propagation of both negative and positive ionization fronts in streamer discharges. We show that fronts accelerate when random charge creation events are present. This effect might play a similar role to photoionization in order to make the front move faster.
Centers for Disease Control (CDC) Podcasts
2010-12-13
This podcast explains the ways people can stay healthy and avoid the flu when traveling this winter. Created: 12/13/2010 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID). Date Released: 12/13/2010.
Travel time reliability modeling.
2011-07-01
This report includes three papers as follows: : 1. Guo F., Rakha H., and Park S. (2010), "A Multi-state Travel Time Reliability Model," : Transportation Research Record: Journal of the Transportation Research Board, n 2188, : pp. 46-54. : 2. Park S.,...
[Pre-travel advice and patient education of Hungarian travellers].
Lengyel, Ingrid; Felkai, Péter
2018-03-01
According to international surveys, over half of the travellers face some kind of health issue when travelling. The overwhelming majority of travel-related illnesses can be prevented with pre-travel medical consultations, but the syllabus and content of the consultation have to match the travel habits and culture of the given society. This publication explores the specificities and travel habits of Hungarian travellers. One hundred participants of a travel exhibition completed a survey about their international travel. As the survey was not representative, the data could only be processed through simple statistical methods. However, since the exhibition was presumably attended by those wishing to travel, the conclusions drawn from the results are worth publishing, since no similar survey in Hungary has been published before. Based on the suitable classification of age groups in travel medicine, 11% of the participants were adolescents / young adults (aged 15-24), 81% adults (25-59) and 8% elderly (60-74). Twenty-eight percent of the participants travel multiple times a year, 40% yearly and 32% of them less frequently; 16% of the adults, 8% of the adolescents and 4% of the elderly age group travel multiple times a year. The travel destinations of Hungarian travellers have remained practically unchanged since a study was conducted 13 years ago: the vast majority (95%) travelled within Europe, 2% to the United States, and 11% of them elsewhere. Since Hungarians do not travel to endemic areas, only 5% consulted their general practitioners (GPs) prior to travelling, and 29% did when they had to be vaccinated. Forty-two percent of those wishing to travel never consult their GPs, even though 29% of them are aware of some chronic illness. Instead, 51% gather their health information from the internet and only 6% from their doctors. By the contradiction between the poor health status of the majority of Hungarian travellers and the negligence of seeking pre-travel advice
Do British travel agents provide adequate health advice for travellers?
Lawlor, D A; Burke, J; Bouskill, E; Conn, G; Edwards, P; Gillespie, D
2000-01-01
Travel-related illness is a burden for primary care, with more than two million travellers consulting a general practitioner each year. The annual cost of travel-related illness in the United Kingdom is 11 million Pounds. Travel agents are in a unique position to influence this burden as the most common and most serious problems are preventable with simple advice and/or immunisation. This study, using covert researchers, suggests this potential is not being fully utilised. PMID:10954940
The Tourist Itinerary Travel Loop: historical and contemporary travel characteristics
Lundgren, Jan O.
2012-01-01
In today’s tourist travel, the travel loop represents a very popular itinerary design, although the circumstances under which it is applied, as well as its geographic scale, often differ from the grandiose loop designs of centuries past. During the past couple of decades, a popular kind of new travel has emerged, the cruise-ship travel phenomenon, which often is arranged as quite an extensive itinerary loop. . However, the cruises can also be transoceanic, even global, with the tourist flying...
Malaria: prevention in travellers.
Croft, Ashley M
2010-07-12
Malaria transmission occurs most frequently in environments with humidity greater than 60% and ambient temperature of 25 °C to 30 °C. Risks increase with longer visits and depend on activity. Infection can follow a single mosquito bite. Incubation is usually 10 to 14 days but can be up to 18 months depending on the strain of parasite. We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of non-drug preventive interventions in non-pregnant adult travellers? What are the effects of drug prophylaxis in non-pregnant adult travellers? What are the effects of antimalaria vaccines in adult and child travellers? What are the effects of antimalaria interventions in child travellers, pregnant travellers, and in airline pilots? We searched: Medline, Embase, The Cochrane Library, and other important databases up to November 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 79 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: aerosol insecticides, amodiaquine, air conditioning and electric fans, atovaquone-proguanil, biological control measures, chloroquine (alone or with proguanil), diethyltoluamide (DEET), dietary supplementation, doxycycline, electronic mosquito repellents, full-length and light-coloured clothing, insecticide-treated clothing/nets, mefloquine, mosquito coils and vapourising mats, primaquine, pyrimethamine-dapsone, pyrimethamine-sulfadoxine, smoke, topical (skin-applied) insect repellents, and vaccines.
Validation of a multimodal travel simulator with travel information provision
Chorus, C.G.; Molin, E.J.E.; Arentze, T.A.; Hoogendoorn, S.P.; Timmermans, H.J.P.; Wee, van G.P.
2007-01-01
This paper presents a computer based travel simulator for collecting data concerning the use of next-generation ATIS and their effects on traveler decision making in a multimodal travel environment. The tool distinguishes itself by presenting a completely abstract multimodal transport network, where
Valuation of Travel Time and TravelIer Information
Rietveld, Piet
2003-01-01
The value of travel time plays an important role in cost benefit analysis of infrastructureprojects. However, the issue of uncertainty on travel times and the implications this has forestimations of travel time values has received much less attention in the literature. In thispaper we compare
Writing Travel in the Anthropocene
DEFF Research Database (Denmark)
Graulund, Rune
2016-01-01
the Anthropocene - which is to say an age in which nowhere, not the furthest reachest of the stratosphere nor the lowest point in the marine abyss, are untouched by the activities and detritus of humankind. The essay will give a short overview of the manner in which the notion of 'travel' has been contested......Travel writing critics have proclaimed the end of travel since at least the beginning of the 20th Century. Yet the global age of the 21st century presents us with a range a problems that challenge the notion of travel in manners that neither travellers, travel writers, nor travel writing critics...... could have imagined just a century ago. Globalisation and increased mobility, whether it is that of the privileged few who can travel on holiday on jet airplanes, or that of the immigrant labourer seeking employment by crossing borders on foot, have meant millions (if not indeed billions) are constantly...
Knowledge Representation in Travelling Texts
DEFF Research Database (Denmark)
Mousten, Birthe; Locmele, Gunta
2014-01-01
Today, information travels fast. Texts travel, too. In a corporate context, the question is how to manage which knowledge elements should travel to a new language area or market and in which form? The decision to let knowledge elements travel or not travel highly depends on the limitation...... and the purpose of the text in a new context as well as on predefined parameters for text travel. For texts used in marketing and in technology, the question is whether culture-bound knowledge representation should be domesticated or kept as foreign elements, or should be mirrored or moulded—or should not travel...... at all! When should semantic and pragmatic elements in a text be replaced and by which other elements? The empirical basis of our work is marketing and technical texts in English, which travel into the Latvian and Danish markets, respectively....
Travel opinion leaders and seekers
DEFF Research Database (Denmark)
Yoo, Kyung-Hyan; Gretzel, Ulrike; Zach, Florian
2011-01-01
While opinion leadership has been recognized as important in tourism, there has been very little empirical research investigating the phenomenon. Given new developments in social media technologies, it is especially important to understand whether travel opinion leadership and seeking are drivers...... of specific social media perceptions and behaviours. Based on an online survey of US online travellers, this paper seeks to identify travel opinion leaders and seekers and their characteristics. Further, the research conducted investigated linkages between travel opinion leadership/seeking and travel social...... media use. The findings suggest that travel opinion leadership and seeking are distinct but connected. Both opinion leaders and seekers are technology savvy, young, educated, involved in travel planning and engaged in social media use for travel. What distinguishes opinion leaders is their greater...
Hydrodynamic instabilities in an ablation front
International Nuclear Information System (INIS)
Piriz, A R; Portugues, R F
2004-01-01
The hydrodynamic stability of an ablation front is studied for situations in which the wavelength of the perturbations is larger than the distance to the critical surface where the driving radiation is absorbed. An analytical model is presented, and it shows that under conditions in which the thermal flux is limited within the supercritical region of the ablative corona, the front may behave like a flame or like an ablation front, depending on the perturbation wavelength. For relatively long wavelengths the critical and ablation surfaces practically lump together into a unique surface and the front behaves like a flame, whereas for the shortest wavelengths the ablation front substructure is resolved
Hydrodynamic instabilities in an ablation front
Energy Technology Data Exchange (ETDEWEB)
Piriz, A R; Portugues, R F [E.T.S.I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)
2004-06-01
The hydrodynamic stability of an ablation front is studied for situations in which the wavelength of the perturbations is larger than the distance to the critical surface where the driving radiation is absorbed. An analytical model is presented, and it shows that under conditions in which the thermal flux is limited within the supercritical region of the ablative corona, the front may behave like a flame or like an ablation front, depending on the perturbation wavelength. For relatively long wavelengths the critical and ablation surfaces practically lump together into a unique surface and the front behaves like a flame, whereas for the shortest wavelengths the ablation front substructure is resolved.
International business travel: impact on families and travellers.
Espino, C M; Sundstrom, S M; Frick, H L; Jacobs, M; Peters, M
2002-05-01
Spouses and staff of the World Bank Group (WBG) were questioned about the impact of international business travel on families and travellers. Dependent variables were self reported stress, concern about the health of the traveller, and negative impact on the family. We hypothesised that several travel factors (independent variables) would be associated with these impacts. These travel factors had to do with the frequency, duration, and predictability of travel and its interference with family activities. Survey forms were developed and distributed to all spouses of travelling staff as well as a small sample of operational staff. Kendall's tau b correlation coefficients of response frequencies were computed with the data from scaled items. Written responses to open ended questions were categorised. Response rates for spouses and staff were 24% and 36%, respectively. Half the spouse sample (n=533) and almost 75% of the staff sample (n=102) reported high or very high stress due to business travel. Self reported spouse stress was associated with six out of eight travel factors. Female spouses, those with children, and younger spouses reported greater stress. Self reported staff stress was significantly associated with four out of nine travel factors. Further insight into how business travel affects families and staff (including children's behavioural changes) and how families cope was gained through responses to written questions. The findings support the notion that lengthy and frequent travel and frequent changes in travel dates which affect family plans, all characteristic of WBG missions, negatively affects many spouses and children (particularly young children) and that the strain on families contributes significantly to the stress staff feel about their travel. Policies or management practices that take into consideration family activities and give staff greater leeway in controlling and refusing travel may help relieve stress.
Controlling front-end electronics boards using commercial solutions
Beneyton, R; Jost, B; Schmeling, S
2002-01-01
LHCb is a dedicated B-physics experiment under construction at CERN's large hadron collider (LHC) accelerator. This paper will describe the novel approach LHCb is taking toward controlling and monitoring of electronics boards. Instead of using the bus in a crate to exercise control over the boards, we use credit-card sized personal computers (CCPCs) connected via Ethernet to cheap control PCs. The CCPCs will provide a simple parallel, I2C, and JTAG buses toward the electronics board. Each board will be equipped with a CCPC and, hence, will be completely independently controlled. The advantages of this scheme versus the traditional bus-based scheme will be described. Also, the integration of the controls of the electronics boards into a commercial supervisory control and data acquisition (SCADA) system will be shown. (5 refs).
Light-front wave function of composite system with spin
International Nuclear Information System (INIS)
Karmanov, V.A.
1979-01-01
The method to construct the relativistic wave function with spin on the light front is developed. The spin structure of the deuteron wave function in relativistic range is found. The calculation methods are illustrated by the calculation of elastic pd-scattering cross section. The consideration carried out is equivalent to the solution of the problem of taking into account the spins and angular momenta in the parton wave functions in the infinite momentum frame
Dipolarization Fronts from Reconnection Onset
Sitnov, M. I.; Swisdak, M. M.; Merkin, V. G.; Buzulukova, N.; Moore, T. E.
2012-12-01
Dipolarization fronts observed in the magnetotail are often viewed as signatures of bursty magnetic reconnection. However, until recently spontaneous reconnection was considered to be fully prohibited in the magnetotail geometry because of the linear stability of the ion tearing mode. Recent theoretical studies showed that spontaneous reconnection could be possible in the magnetotail geometries with the accumulation of magnetic flux at the tailward end of the thin current sheet, a distinctive feature of the magnetotail prior to substorm onset. That result was confirmed by open-boundary full-particle simulations of 2D current sheet equilibria, where two magnetotails were separated by an equilibrium X-line and weak external electric field was imposed to nudge the system toward the instability threshold. To investigate the roles of the equilibrium X-line, driving electric field and other parameters in the reconnection onset process we performed a set of 2D PIC runs with different initial settings. The investigated parameter space includes the critical current sheet thickness, flux tube volume per unit magnetic flux and the north-south component of the magnetic field. Such an investigation is critically important for the implementation of kinetic reconnection onset criteria into global MHD codes. The results are compared with Geotail visualization of the magnetotail during substorms, as well as Cluster and THEMIS observations of dipolarization fronts.
CARLSON WAGONLIT TRAVEL
2004-01-01
CARLSON WAGONLIT TRAVEL would like to remind you of the entry formalities applicable to those travelling to the United States. Nationals of Switzerland and of the following countries : Andorra, Australia, Austria, Belgium, Brunei, Denmark, Finland, France, Germany, Iceland, Ireland, Italy, Japan, Liechtenstein, Luxemburg, Monaco, Netherlands, New Zealand, Norway, Portugal, San Marino, Singapore, Slovenia, Spain, Sweden and the United Kingdom, entering the United States under the Visa Waiver Program (no visa requirement), must be in possession of an machine-readable passport that is valid for at least six months after the date of the return trip. Children, including infants, must have their own passport. An entry in the parents' passport is not sufficient. For entry into the United States, an e-ticket (fax or e-mail confirmation or passenger receipt) or a return ticket to the departure point or a ticket to a subsequent onward destination (valid for 90 days) must be presented together with the green ...
Grauer, Albert D.
2014-11-01
Travelers In The Night is an engaging and informative series of two minute radio programs about asteroids, comets, spacecraft, and other objects in space. The pieces are evergreen in that they are current but not dated. They are published on the Public Radio Exchange and carried by a number of radio stations. For teachers, students, and kids of all ages, the script for each piece and the start of a path for further inquiry can be found on the website travelersinthenight.org . The Travelers InThe Night Pieces are written and produced by an observing member of the Catalina Sky Survey Team at the University of Arizona. DPS members are encouraged to submit program ideas which can be developed to feature their research efforts.
María José Caride; Eduardo L. Giménez
2003-01-01
It is commonly recognized the relevance of transportation costs for studying recre- ational demand. However, these costs are related with travel and modal choice deci- sions. This paper o ers a theoretical explanation of the new generation of the demand for recreational goods at destiny after the introduction of a new transportation mode that is not the cheapest nor the fastest among the available modes. The main feature of the model deals with the transportation mode-dependent preferences. T...
Choice, changeover, and travel
Baum, William M.
1982-01-01
Since foraging in nature can be viewed as instrumental behavior, choice between sources of food, known as “patches,” can be viewed as choice between instrumental response alternatives. Whereas the travel required to change alternatives deters changeover in nature, the changeover delay (COD) usually deters changeover in the laboratory. In this experiment, pigeons were exposed to laboratory choice situations, concurrent variable-interval schedules, that were standard except for the introduction...
DEFF Research Database (Denmark)
Lund, Rebecca; Meriläinen, Susan; Tienari, Janne
2013-01-01
In this chapter we offer insights into the social construction of diversity in Finnish organizations and society. In Finnish organizations, gender is highlighted while other markers of diversity are blotted out. 'Non-Finns' become subject to cultural assimilation. The US-based concept of Diversit...... Management becomes adopted and adapted in particular ways. Standardized concepts of diversity and its management do not travel, rather they become translated locally. In organizational practice, globalization is slow and laborious....
Centers for Disease Control (CDC) Podcasts
2008-05-15
Malaria is a serious mosquito-borne disease that can lead to death. This podcast discusses malaria risk when traveling to tropical areas, as well as how to protect yourself and your family from malaria infection. Created: 5/15/2008 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED). Date Released: 5/29/2008.
Travelling water waves with compactly supported vorticity
International Nuclear Information System (INIS)
Shatah, Jalal; Walsh, Samuel; Zeng, Chongchun
2013-01-01
In this paper, we prove the existence of two-dimensional, travelling, capillary-gravity, water waves with compactly supported vorticity. Specifically, we consider the cases where the vorticity is a δ-function (a point vortex), or has small compact support (a vortex patch). Using a global bifurcation theoretic argument, we construct a continuum of finite-amplitude, finite-vorticity solutions for the periodic point vortex problem. For the non-periodic case, with either a vortex point or patch, we prove the existence of a continuum of small-amplitude, small-vorticity solutions. (paper)
Pickover, Clifford A.
1999-09-01
"Bucky Fuller thought big," Wired magazine recently noted, "Arthur C. Clarke thinks big, but Cliff Pickover outdoes them both." In his newest book, Cliff Pickover outdoes even himself, probing a mystery that has baffled mystics, philosophers, and scientists throughout history--What is the nature of time?In Time: A Traveler's Guide , Pickover takes readers to the forefront of science as he illuminates the most mysterious phenomenon in the universe--time itself. Is time travel possible? Is time real? Does it flow in one direction only? Does it have a beginning and an end? What is eternity? Pickover's book offers a stimulating blend of Chopin, philosophy, Einstein, and modern physics, spiced with diverting side-trips to such topics as the history of clocks, the nature of free will, and the reason gold glitters. Numerous diagrams ensure readers will have no trouble following along.By the time we finish this book, we understand a wide variety of scientific concepts pertaining to time. And most important, we will understand that time travel is, indeed, possible.
CERN Bulletin
2010-01-01
For the first time the new CERN travelling exhibition has gone abroad. The venue is Torino, in Italy, where it is being shown at the Museum of Natural Science in the framework of the activities of the EuroScience Open Forum (ESOF 2010). Soon after the event, the exhibition will fly to Copenhagen. The CERN traveling exhibition was inaugurated in 2009. The new ‘Accelerating Science’ exhibition was inaugurated in 2009 as part of the celebrations to mark the 450th anniversary of the University of Geneva. “CERN’s travelling exhibition is an important tool for outreach in our Member states as it carries the main messages that constitute the backbone of the Laboratory’s education and communication policy”, explains Rolf Landua, head of the Education Group, which manages the exhibition. “The 2010 European Science Open Forum in Torino will gather a lot of experts and visitors from the general public who will be able to experience in an ...
2006-01-01
Carlson Wagonlit Travel wishes to remind you of the following conditions concerning travel to the USA. Passport conditions Since 26 October 2004, nationals of the countries covered by the US Visa Waiver Programme have been required to present a valid machine-readable passport when entering the United States. Failing this, they require a valid US non-immigrant visa in addition to their passport. Passports issued after 25 October 2005 must also bear a digital photograph. Passports issued after 25 October 2006 must contain biometric data to allow visa-free entry to the US. Advanced Passenger Information System (APIS) form Since 4 October 2005, all non-US citizens travelling to the USA have been required to complete the APIS form before departure and present it when they check in. This new procedure will certainly increase the time it takes to check in. We therefore advise passengers to present themselves at the respective check-in desk in good time. The APIS form can be downloaded from our homepage: w...
Vaschetto, Emilio
2014-01-01
This article explores the notion of "wandering" through the use of some phenomena enrolled at the dawn of modernity such as the Rousseau dromomanie's philosopher and writer, the origin of the first mad traveler (Albert Dadas), epidemics of mad travelers Europe and romantic tourism (with renewed acquires significance in the "beat generation" of the twentieth century). These historical facts are "mounting" as play contemporary manifestations such as loss, disorientation, to lose one's way, and wandering without reducing them only to clinical psychosis. Readings of classic psychiatrists such as Régis, Foville, Sérieux and Capgras, Tissié, go hand in hand with the current readings of the philosopher Ian Hacking and critics of pop culture as S. Reynolds and D. Diederichsen, illustrating how the travel's phenomenon can make different subjective configurations depending on historical times. In conclusion it is noted that not only psychosis exposes the wandering soul of suffering but there are also subject positions (as will be exemplified in a clinical case) and go no further nesting wandering into human existence.
Traveling wave behavior for a generalized fisher equation
International Nuclear Information System (INIS)
Feng Zhaosheng
2008-01-01
There is the widespread existence of wave phenomena in physics, chemistry and biology. This clearly necessitates a study of traveling waves in depth and of the modeling and analysis involved. In the present paper, we study a nonlinear reaction-diffusion equation, which can be regarded as a generalized Fisher equation. Applying the Cole-Hopf transformation and the first integral method, we obtain a class of traveling solitary wave solutions for this generalized Fisher equation
Front Propagation in Stochastic Neural Fields
Bressloff, Paul C.
2012-01-01
We analyze the effects of extrinsic multiplicative noise on front propagation in a scalar neural field with excitatory connections. Using a separation of time scales, we represent the fluctuating front in terms of a diffusive-like displacement (wandering) of the front from its uniformly translating position at long time scales, and fluctuations in the front profile around its instantaneous position at short time scales. One major result of our analysis is a comparison between freely propagating fronts and fronts locked to an externally moving stimulus. We show that the latter are much more robust to noise, since the stochastic wandering of the mean front profile is described by an Ornstein-Uhlenbeck process rather than a Wiener process, so that the variance in front position saturates in the long time limit rather than increasing linearly with time. Finally, we consider a stochastic neural field that supports a pulled front in the deterministic limit, and show that the wandering of such a front is now subdiffusive. © 2012 Society for Industrial and Applied Mathematics.
On the Travel Emissions of Sustainability Science Research
Directory of Open Access Journals (Sweden)
Timothy Waring
2014-05-01
Full Text Available This paper presents data on carbon emissions generated by travel undertaken for a major sustainability science research effort. Previous research has estimated CO2 emissions generated by individual scientists, by entire academic institutions, or by international climate conferences. Here, we sought to investigate the size, distribution and factors affecting the carbon emissions of travel for sustainability research in particular. Reported airline and automobile travel of participants in Maine’s Sustainability Solutions Initiative were used to calculate the carbon dioxide emissions attributable to research-related travel over a three-year period. Carbon emissions varied substantially by researcher and by purpose of travel. Travel for the purpose of dissemination created the largest carbon footprint. This result suggests that alternative networking and dissemination models are needed to replace the high carbon costs of annual society meetings. This research adds to literature that questions whether the cultural demands of contemporary academic careers are compatible with climate stabilization. We argue that precise record keeping and routine analysis of travel data are necessary to track and reduce the climate impacts of sustainability research. We summarize the barriers to behavioral change at individual and organizational levels and conclude with suggestions for reducing climate impacts of travel undertaken for sustainability research.
Stickel, L.F.; King, John A.
1968-01-01
The concept of home range was expressed by Seton (1909) in the term 'home region,' which Burr (1940, 1943) clarified with a definition of home range and exemplified in a definitive study of Peromyscus in the field. Burt pointed out the ever-changing characteristics of home-range area and the consequent absence of boundaries in the usual sense--a finding verified by investigators thereafter. In the studies summarized in this paper, sizes of home ranges of Peromyscus varied within two magnitudes, approximately from 0.1 acre to ten acres, in 34 studies conducted in a variety of habitats from the seaside dunes of Florida to the Alaskan forests. Variation in sizes of home ranges was correlated with both environmental and physiological factors; with habitat it was conspicuous, both in the same and different regions. Food supply also was related to size of home range, both seasonally and in relation to habitat. Home ranges generally were smallest in winter and largest in spring, at the onset of the breeding season. Activity and size also were affected by changes in weather. Activity was least when temperatures were low and nights were bright. Effects of rainfall were variable. Sizes varied according to sex and age; young mice remained in the parents' range until they approached maturity, when they began to travel more widely. Adult males commonly had larger home ranges than females, although there were a number of exceptions. An inverse relationship between population density and size of home range was shown in several studies and probably is the usual relationship. A basic need for activity and exploration also appeared to influence size of home range. Behavior within the home range was discussed in terms of travel patterns, travels in relation to home sites and refuges, territory, and stability of size of home range. Travels within the home range consisted of repeated use of well-worn trails to sites of food, shelter, and refuge, plus more random exploratory travels
The upgraded Tevatron front end
International Nuclear Information System (INIS)
Glass, M.; Zagel, J.; Smith, P.; Marsh, W.; Smolucha, J.
1990-01-01
We are replacing the computers which support the CAMAC crates in the Fermilab accelerator control system. We want a significant performance increase, but we still want to be able to service scores of different varieties of CAMAC cards in a manner essentially transparent to console applications software. Our new architecture is based on symmetric multiprocessing. Several processors on the same bus, each running identical software, work simultaneously at satisfying different pieces of a console's request for data. We dynamically adjust the load between the processors. We can obtain more processing power by simply plugging in more processor cards and rebooting. We describe in this paper what we believe to be the interesting architectural features of the new front-end computers. We also note how we use some of the advanced features of the Multibus TM II bus and the Intel 80386 processor design to achieve reliability and expandability of both hardware and software. (orig.)
Directory of Open Access Journals (Sweden)
Étienne Poncelet
2011-06-01
Full Text Available De la porte d’eau de la Basse Deûle jusqu’au fort Saint-Sauveur, le front oriental de Lille, fortifié à l’époque espagnole, glisse ses courtines dans les entrelacs du périphérique et des gares. L’enjeu urbain actuel consiste à s’appuyer sur ces murs historiques pour « passer malgré tout » à travers cet écheveau urbain et retisser les fils de la continuité des promenades au cœur de la ville. Moins connus que le front occidental de la reine des citadelles, ces anciens espaces militaires sont une chance pour l’urbanisme de demain dont les opérations en cours de la Porte de Gand et de la Basse Deûle témoignent déjà.The east wall, at Lille, fortified during the period of Spanish occupation, extends from the Porte d'Eau de la Basse-Deûle to the Saint-Sauveur fort. Its curtain walls emerge today in a landscape of ring roads and railway territories. The issue today is to profit from these historic walls in order to make some sense of the urban chaos and to reinstate some urban continuity in the city-centre walkways. Although they are not as well known as the western wall of this major fortified city, these former military properties are an exciting opportunity for tomorrow's town-planners, as the operations already underway at the Porte de Gand et de la Basse Deûle suggest.
Sistem Informasi Hotel Modul Front Office Berbasis Web
Directory of Open Access Journals (Sweden)
James Kawilarang
2015-04-01
Full Text Available Hotel merupakan fasilitas yang sudah menjadi kebutuhan yang sangat penting bagi masyarakat meliputi kebutuhan traveling antar kota dalam urusan bisnis maupun wisata. Teknologi informasi dalam pengolahan informasi sangatlah diperlukan dalam pengolahan data instansi hotel agar data dapat dikelola dengan baik sehingga membantu pengelola dalam melakukan pengambilan keputusan. Berdasarkan kebutuhan yang mendasar dalam pengolahan data manajerial sebuah hotel yang merupakan pusat bisnis pariwisata Bali, maka terciptalah suatu ide untuk membuat sebuah sistem berbasis web dan terintegrasi dengan perangkat Android. Sistem yang berbasis web dan terintergrasi dengan perangkat Android merupakan sebuah solusi yang tepat untuk mengatasi permasalahan kebutuhan pengolahan data manajerial hotel yang berisfat dinamis dimana sistem informasi berbasis web mudah dikelola serta dapat dirancang dengan antarmuka yang fleksibel. Perkembangan teknologi mobile Android yang kini digunakan hampir oleh semua khalayak pengguna handphone juga merupakan sebuah nilai tambah tersendiri terhadap sistem pengolahan data tesebut, sehingga sistem mampu memberikan mobilitas yang lebih terhadap pengguna. Kata kunci : Teknologi, Sistem Informasi, Hotel, Front Office
Muon front end for the neutrino factory
Directory of Open Access Journals (Sweden)
C. T. Rogers
2013-04-01
Full Text Available In the neutrino factory, muons are produced by firing high-energy protons onto a target to produce pions. The pions decay to muons and pass through a capture channel known as the muon front end, before acceleration to 12.6 GeV. The muon front end comprises a variable frequency rf system for longitudinal capture and an ionization cooling channel. In this paper we detail recent improvements in the design of the muon front end.
Muon front end for the neutrino factory
Rogers, C T; Prior, G; Gilardoni, S; Neuffer, D; Snopok, P; Alekou, A; Pasternak, J
2013-01-01
In the neutrino factory, muons are produced by firing high-energy protons onto a target to produce pions. The pions decay to muons and pass through a capture channel known as the muon front end, before acceleration to 12.6 GeV. The muon front end comprises a variable frequency rf system for longitudinal capture and an ionization cooling channel. In this paper we detail recent improvements in the design of the muon front end.
Fellow travellers: Working memory and mental time travel in rodents.
Dere, Ekrem; Dere, Dorothea; de Souza Silva, Maria Angelica; Huston, Joseph P; Zlomuzica, Armin
2017-03-19
The impairment of mental time travel is a severe cognitive symptom in patients with brain lesions and a number of neuropsychiatric disorders. Whether animals are also able to mentally travel in time both forward and backward is still a matter of debate. In this regard, we have proposed a continuum of mental time travel abilities across different animal species, with humans being the species with the ability to perform most sophisticated forms of mental time travel. In this review and perspective article, we delineate a novel approach to understand the evolution, characteristics and function of human and animal mental time travel. Furthermore, we propose a novel approach to measure mental time travel in rodents in a comprehensive manner using a test battery composed of well-validated and easy applicable tests. Copyright © 2017. Published by Elsevier B.V.
Coronal mass ejection shock fronts containing the two types of intermediate shocks
International Nuclear Information System (INIS)
Steinolfson, R.S.; Hundhausen, A.J.
1990-01-01
Numerical solutions of the time-dependent, magnetohydrodynamic (MHD) equations in two dimensions are used to demonstrate the formation of both types of intermediate shocks in a single shock front for physical conditions that are an idealization of those expected to occur in some observed coronal mass ejections. The key to producing such a shock configuration in the simulations is the use of an initial atmosphere containing a magnetic field representative of that in a coronal streamer with open field lines overlying a region of closed field lines. Previous attempts using just open field lines (perpendicular to the surface) produced shock configurations containing just one of the two intermediate shock types. A schematic of such a shock front containing both intermediate shock types has been constructed previously based solely on the known properties of MHD shocks from the Rankine-Hugoniot equations and specific requirements placed on the shock solution at points along the front where the shock normal and upstream magnetic field are aligned. The shock front also contains, at various locations along the front, a hydrodynamic (nonmagnetic) shock, a switch-on shock, and a fast shock in addition to the intermediate shocks. This particular configuration occurs when the shock front speed exceeds the upstream (preshock) intermediate wave speed but is less than a critical speed defined in the paper (equation 1) along at least some portion of the shock front. A distinctive feature of the front is that it is concave upward (away from the surface) near the region where the field in the preshock plasma is normal to the front of near the central portion of the shock front
Health hazards of international travel.
Cossar, J H; Reid, D
1989-01-01
The growth of travel and the increasing numbers of those affected by travel-related illnesses, some of a serious nature, will cause this subject to demand the attention of the medical profession, the travel trade, travellers themselves and the health authorities of countries receiving tourists. Provision of appropriate advice for the traveller is a shared responsibility, best channelled mainly through travel agencies; it can moreover be shown to be cost-beneficial. Continued monitoring of illness in travellers and provision of information systems geared to this problem and its prevention are fully justified. They should be based on traditional channels of communication and currently-available modern technology, and be readily accessible to medical and related workers. Increased collaboration between medical workers, health educators and those involved in the travel trade would be a positive and useful contribution towards the reduction of illness and discomfort among travellers and the associated expense incurred by the various national health services concerned. There are clearly economic benefits from the development of international tourism, but these have to be balanced in countries accepting tourists by attention to the prevention of illnesses associated with travel.
Aerodynamics of a cycling team in a time trial: does the cyclist at the front benefit?
International Nuclear Information System (INIS)
Iniguez-de-la Torre, A; Iniguez, J
2009-01-01
When seasonal journeys take place in nature, birds and fishes migrate in groups. This provides them not only with security but also a considerable saving of energy. The power they need to travel requires overcoming aerodynamic or hydrodynamic drag forces, which can be substantially reduced when the group travels in an optimal arrangement. Also in this area, humans imitate nature, which is especially evident in the practice of outdoor sports and motor competitions. Cycle races, in which speeds of up to 15 m s -1 are frequent, offer great opportunities to appreciate the advantage of travelling in a group. Here we present a brief analysis of the aerodynamics of a cycling team in a time-trial challenge, showing how each rider is favoured according to his position in the group. We conclude that the artificial tail wind created by the team also benefits the cyclist at the front by about 5%.
Aerodynamics of a cycling team in a time trial: does the cyclist at the front benefit?
Íñiguez-de-la Torre, A.; Íñiguez, J.
2009-11-01
When seasonal journeys take place in nature, birds and fishes migrate in groups. This provides them not only with security but also a considerable saving of energy. The power they need to travel requires overcoming aerodynamic or hydrodynamic drag forces, which can be substantially reduced when the group travels in an optimal arrangement. Also in this area, humans imitate nature, which is especially evident in the practice of outdoor sports and motor competitions. Cycle races, in which speeds of up to 15 m s-1 are frequent, offer great opportunities to appreciate the advantage of travelling in a group. Here we present a brief analysis of the aerodynamics of a cycling team in a time-trial challenge, showing how each rider is favoured according to his position in the group. We conclude that the artificial tail wind created by the team also benefits the cyclist at the front by about 5%.
Traveling waves in lattice differential equations with distributed maturation delay
Directory of Open Access Journals (Sweden)
Hui-Ling Niu
2013-07-01
Full Text Available In this paper we derive a lattice model with infinite distributed delay to describe the growth of a single-species population in a 2D patchy environment with infinite number of patches connected locally by diffusion and global interaction. We consider the existence of traveling wave solutions when the birth rate is large enough that each patch can sustain a positive equilibrium. When the birth function is monotone, we prove that there exists a traveling wave solution connecting two equilibria with wave speed $c>c^*(\\theta$ by using the monotone iterative method and super and subsolution technique, where $\\theta\\in [0,2\\pi]$ is any fixed direction of propagation. When the birth function is non-monotone, we prove the existence of non-trivial traveling wave solutions by constructing two auxiliary systems satisfying quasi-monotonicity.
Traveling solitons in Lorentz and CPT breaking systems
International Nuclear Information System (INIS)
Souza Dutra, A. de; Correa, R. A. C.
2011-01-01
In this work we present a class of traveling solitons in Lorentz and CPT breaking systems. In the case of Lorentz violating scenarios, as far as we know, only static solitonic configurations were analyzed up to now in the literature. Here it is shown that it is possible to construct some traveling solitons which cannot be mapped into static configurations by means of Lorentz boosts due to explicit breaking. In fact, the traveling solutions cannot be reached from the static ones by using something similar to a Lorentz boost in those cases. Furthermore, in the model studied, a complete set of exact solutions is obtained. The solutions present a critical behavior controlled by the choice of an arbitrary integration constant.
Effective Hamiltonian for travelling discrete breathers
MacKay, Robert S.; Sepulchre, Jacques-Alexandre
2002-05-01
Hamiltonian chains of oscillators in general probably do not sustain exact travelling discrete breathers. However solutions which look like moving discrete breathers for some time are not difficult to observe in numerics. In this paper we propose an abstract framework for the description of approximate travelling discrete breathers in Hamiltonian chains of oscillators. The method is based on the construction of an effective Hamiltonian enabling one to describe the dynamics of the translation degree of freedom of moving breathers. Error estimate on the approximate dynamics is also studied. The concept of the Peierls-Nabarro barrier can be made clear in this framework. We illustrate the method with two simple examples, namely the Salerno model which interpolates between the Ablowitz-Ladik lattice and the discrete nonlinear Schrödinger system, and the Fermi-Pasta-Ulam chain.
Hu, Xiao-Bing; Wang, Ming; Di Paolo, Ezequiel
2013-06-01
Searching the Pareto front for multiobjective optimization problems usually involves the use of a population-based search algorithm or of a deterministic method with a set of different single aggregate objective functions. The results are, in fact, only approximations of the real Pareto front. In this paper, we propose a new deterministic approach capable of fully determining the real Pareto front for those discrete problems for which it is possible to construct optimization algorithms to find the k best solutions to each of the single-objective problems. To this end, two theoretical conditions are given to guarantee the finding of the actual Pareto front rather than its approximation. Then, a general methodology for designing a deterministic search procedure is proposed. A case study is conducted, where by following the general methodology, a ripple-spreading algorithm is designed to calculate the complete exact Pareto front for multiobjective route optimization. When compared with traditional Pareto front search methods, the obvious advantage of the proposed approach is its unique capability of finding the complete Pareto front. This is illustrated by the simulation results in terms of both solution quality and computational efficiency.
Front tracking for hyperbolic conservation laws
Holden, Helge
2015-01-01
This is the second edition of a well-received book providing the fundamentals of the theory hyperbolic conservation laws. Several chapters have been rewritten, new material has been added, in particular, a chapter on space dependent flux functions, and the detailed solution of the Riemann problem for the Euler equations. Hyperbolic conservation laws are central in the theory of nonlinear partial differential equations and in science and technology. The reader is given a self-contained presentation using front tracking, which is also a numerical method. The multidimensional scalar case and the case of systems on the line are treated in detail. A chapter on finite differences is included. From the reviews of the first edition: "It is already one of the few best digests on this topic. The present book is an excellent compromise between theory and practice. Students will appreciate the lively and accurate style." D. Serre, MathSciNet "I have read the book with great pleasure, and I can recommend it to experts ...
Approaches to groundwater travel time
International Nuclear Information System (INIS)
Kaplan, P.; Klavetter, E.; Peters, R.
1989-01-01
One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations, Title 10 CFR 60.113 (a). The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss the ambiguities associated with the regulatory specification of groundwater travel time, two different interpretations of groundwater travel time, and the effect of the two interpretations on estimates of the groundwater travel time
Approaches to groundwater travel time
International Nuclear Information System (INIS)
Kaplan, P.; Klavetter, E.; Peters, R.
1989-01-01
One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations. The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time, as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss (1) the ambiguities associated with the regulatory specification of groundwater travel time, (2) two different interpretations of groundwater travel time, and (3) the effect of the two interpretations on estimates of the groundwater travel time. 3 refs., 2 figs., 2 tabs
Gleick, James
2016-01-01
From the acclaimed author of The Information and Chaos, here is a mind-bending exploration of time travel: its subversive origins, its evolution in literature and science, and its influence on our understanding of time itself. The story begins at the turn of the previous century, with the young H. G. Wells writing and rewriting the fantastic tale that became his first book and an international sensation: The Time Machine. It was an era when a host of forces was converging to transmute the human understanding of time, some philosophical and some technological: the electric telegraph, the steam railroad, the discovery of buried civilizations, and the perfection of clocks. James Gleick tracks the evolution of time travel as an idea that becomes part of contemporary culture—from Marcel Proust to Doctor Who, from Jorge Luis Borges to Woody Allen. He investigates the inevitable looping paradoxes and examines the porous boundary between pulp fiction and modern physics. Finally, he delves into a temporal shift that...
A study on the front-end VME system of BEPC II
International Nuclear Information System (INIS)
Wang Chunhong
2004-01-01
The front-end VME system is not only the heart of the control system, but also a real-time system. This paper describes the component of the front-end VME (Versa Module Eurocard) system including control computer and some related I/O modules. Particularly, the authors present a best solution for the problems about Vx-Works kernel and BSP running on MVME5100. This is a fundamental setup of the BEPC II control system. (author)
Anthropological Invariants in Travel Behavior
Marchetti, C.
1994-01-01
Personal travel appears to be much more under the control of basic instinct than of economic drive. This may be the reason for the systematic mismatch between the results of cost benefit analysis and the actual behavior of travelers. In this paper a list of the basic instincts that drive and contain travelers' behavior has been put together, showing how they mesh with technological progress and economic constraints.
Counting states of black strings with traveling waves
International Nuclear Information System (INIS)
Horowitz, G.T.; Marolf, D.
1997-01-01
We consider a family of solutions to string theory which depend on arbitrary functions and contain regular event horizons. They describe six-dimensional extremal black strings with traveling waves and have an inhomogeneous distribution of momentum along the string. The structure of these solutions near the horizon is studied and the horizon area computed. We also count the number of BPS string states at weak coupling whose macroscopic momentum distribution agrees with that of the black string. It is shown that the number of such states is given by the Bekenstein-Hawking entropy of the black string with traveling waves. copyright 1997 The American Physical Society
International Nuclear Information System (INIS)
Grey, C.A.
1994-01-01
A picture is drawn of the current supply side of the front-end fuel cycle production capacities in the CIS. Uranium production has been steadily declining, as in the West. Market realities have been reflected in local costs of production since the break-up of the former Soviet Union and some uneconomic mines have been closed. In terms of actual production, Kazakhstan, Russia and Uzbekistan, remain among the top five uranium producers in the world. Western government action has been taken to restrict the market access for natural uranium from the CIS. Reactors in the CIS continue to be supplied with fabricated fuel solely by Russian, though Western fuel fabricators have reduced Russian supplies to Eastern Europe. Russia's current dominance in conversion and enrichment services in both the CIS and Eastern Europe is likely to continue as long as the present surplus low enriched uranium stocks last and surplus production capacity exists. Market penetration in the West has been limited by government action but Russia in 1993 still held about 20% of the world's conversion market and nearly 19% of the enrichment market. (6 figures, 2 tables, 4 references) (UK)
Application of up-front licensing
International Nuclear Information System (INIS)
Grant, S.D.; Snell, V.G.
1995-01-01
AECL has been pioneering 'up-front' licensing of new reactor designs. The CANDU 3 design has been formally reviewed by AECB staff for a number of years. The CANDU 9 design has just started the up-front licensing process. The process gives designers, regulators and potential customers early confidence in the licensability of future plants. (author). 4 refs., 2 tabs
Application of up-front licensing
Energy Technology Data Exchange (ETDEWEB)
Grant, S D [Atomic Energy of Canada Ltd., Saskatoon, SK (Canada); Snell, V G [Atomic Energy of Canada Ltd., Mississauga, ON (Canada)
1996-12-31
AECL has been pioneering `up-front` licensing of new reactor designs. The CANDU 3 design has been formally reviewed by AECB staff for a number of years. The CANDU 9 design has just started the up-front licensing process. The process gives designers, regulators and potential customers early confidence in the licensability of future plants. (author). 4 refs., 2 tabs.
RPC performance vs. front-end electronics
International Nuclear Information System (INIS)
Cardarelli, R.; Aielli, G.; Camarri, P.; Di Ciaccio, A.; Di Stante, L.; Liberti, B.; Pastori, E.; Santonico, R.; Zerbini, A.
2012-01-01
Moving the amplification from the gas to the front-end electronics was a milestone in the development of Resistive Plate Chambers. Here we discuss the historical evolution of RPCs and we show the results obtained with newly developed front-end electronics with threshold in the fC range.
Through the EU's Back and Front Doors
DEFF Research Database (Denmark)
Adler-Nissen, Rebecca
2015-01-01
Through the EU's front- and backdoors: The selective Danish and Norwegian approaches in the Area of Freedom, Security and Justice Rebecca Adler-Nissen......Through the EU's front- and backdoors: The selective Danish and Norwegian approaches in the Area of Freedom, Security and Justice Rebecca Adler-Nissen...
International Nuclear Information System (INIS)
Akaoka, K.; Wakaida, I.
1996-01-01
We controlled the laser wave front through a laser beam simulation experiment propagating through medium. Thus, we confirmed that the RMS, defined as the quadratic mean of the laser beam wave front, dropped to the 1/3 - 1/6 of the pre-control value
Nuclear Physics on the Light Front
Miller, Gerald A.
1999-01-01
High energy scattering experiments involving nuclei are typically analyzed in terms of light front variables. The desire to provide realistic, relativistic wave functions expressed in terms of these variables led me to try to use light front dynamics to compute nuclear wave functions. The progress is summarized here.
Wave fronts of electromagnetic cyclotron harmonic waves
International Nuclear Information System (INIS)
Ohnuma, T.; Watanabe, T.
1982-01-01
In an inhomogeneous high-density magnetized plasma, the spatial properties of the wave fronts and ray trajectories of electromagnetic ordinary and extraordinary cyclotron harmonic waves are investigated. Those waves which are radiated from a local source are found to have wave fronts which are almost parallel to the magnetic field. Also, the reflective properties of the electromagnetic cyclotron harmonic waves are confirmed
End-Users, Front Ends and Librarians.
Bourne, Donna E.
1989-01-01
The increase in end-user searching, the advantages and limitations of front ends, and the role of the librarian in end-user searching are discussed. It is argued that librarians need to recognize that front ends can be of benefit to themselves and patrons, and to assume the role of advisors and educators for end-users. (37 references) (CLB)
Polarization of concave domains by traveling wave pinning.
Directory of Open Access Journals (Sweden)
Slawomir Bialecki
Full Text Available Pattern formation is one of the most fundamental yet puzzling phenomena in physics and biology. We propose that traveling front pinning into concave portions of the boundary of 3-dimensional domains can serve as a generic gradient-maintaining mechanism. Such a mechanism of domain polarization arises even for scalar bistable reaction-diffusion equations, and, depending on geometry, a number of stationary fronts may be formed leading to complex spatial patterns. The main advantage of the pinning mechanism, with respect to the Turing bifurcation, is that it allows for maintaining gradients in the specific regions of the domain. By linking the instant domain shape with the spatial pattern, the mechanism can be responsible for cellular polarization and differentiation.
Travelling gradient thermocouple calibration
International Nuclear Information System (INIS)
Broomfield, G.H.
1975-01-01
A short discussion of the origins of the thermocouple EMF is used to re-introduce the idea that the Peltier and Thompson effects are indistinguishable from one another. Thermocouples may be viewed as devices which generate an EMF at junctions or as integrators of EMF's developed in thermal gradients. The thermal gradient view is considered the more appropriate, because of its better accord with theory and behaviour, the correct approach to calibration, and investigation of service effects is immediately obvious. Inhomogeneities arise in thermocouples during manufacture and in service. The results of travelling gradient measurements are used to show that such effects are revealed with a resolution which depends on the length of the gradient although they may be masked during simple immersion calibration. Proposed tests on thermocouples irradiated in a nuclear reactor are discussed
Directory of Open Access Journals (Sweden)
Novita Lavi N
2013-05-01
Full Text Available The sun exposure brings negative effects on the skin such like early aging, spots and skin cancer as the most terrible effect. To reduce the adverse effects of the sun, it is not enough just to behavioral therapy, but also had no protection from the outside. Especially for travellers that exposed by the sun excessively. There is sunscreen, product specially formulated to absorb or deflect ultraviolet rays. A sunscreen preparation contains chemical compounds that can absorb, scatter or reflect sunlight on the skin. This writing contains about effect of ultraviolet, skin protection from ultraviolet from behavioral aspect, variaty and contents of sunscreen and sunscreen application for travellers. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}
International Travelers' Sociodemographic, Health, and Travel Characteristics: An Italian Study.
Troiano, Gianmarco; Mercone, Astrid; Bagnoli, Alessandra; Nante, Nicola
Approximately the 8% of travelers requires medical care, with the diagnosis of a vaccine-preventable disease. The aim of our study was to analyze the socio-demographic, health and travel characteristics of the Italian international travelers. We conducted a cross sectional study from January 2015 to June 2016, at the Travel Medicine Clinic of Siena, asking the doctor to interview patients who attended the Clinic, recording socio-demographic and travel information, malaria prophylaxis, vaccinations. The data were organized in a database and processed by software Stata®. We collected 419 questionnaires. Patients chose 71 countries for their travels; the favorite destinations were: India (6.31%), Thailand (6.31%), and Brazil (5.10%). The mean length of stay was 36.17 days. Italians, students, and freelancers tended to stay abroad for a longer time (mean: 36.4 days, 59.87 days and 64.16 days respectively). 33.17% of our sample used drugs for malaria chemoprophylaxis: 71.9% of them used Atovaquone/Proguanil (Malarone®), 26.6% used Mefloquine (Lariam®), 1.5% other drugs. The vaccinations that travelers mostly got in our study were to prevent hepatitis A (n = 264), the typhoid fever (n = 187), the Tetanus + Diphtheria + Pertussis (n = 165), the Yellow fever (n = 118) and the cholera (n = 78). Twenty-eight (6.68%) refused some recommended vaccinations. The vaccines mostly refused were for Typhoid fever (n = 20), hepatitis a (n = 9), and cholera (n = 9). Our results demonstrated that Italian international travelers are at-risk because of their poor vaccinations adherence. This implies that pre-travel counseling is fundamental to increase the knowledge of the risks and the compliance of future travelers. Copyright © 2016 Icahn School of Medicine at Mount Sinai. Published by Elsevier Inc. All rights reserved.
A slow pushed front in a Lotka–Volterra competition model
International Nuclear Information System (INIS)
Holzer, Matt; Scheel, Arnd
2012-01-01
We study invasion speeds in the Lotka–Volterra competition model when the rate of diffusion of one species is small. Our main result is the construction of the selected front and a rigorous asymptotic approximation of its propagation speed, valid to second order. We use techniques from geometric singular perturbation theory and geometric desingularization. The main challenge arises from the slow passage through a saddle-node bifurcation. From a perspective of linear versus nonlinear speed selection, this front provides an interesting example as the propagation speed is slower than the linear spreading speed. However, our front shares many characteristics with pushed fronts that arise when the influence of nonlinearity leads to faster than linear speeds of propagation. We show that this is a result of the linear spreading speed arising as a simple pole of the resolvent instead of as a branch pole. Using the pointwise Green's function, we show that this pole poses no a priori obstacle to marginal stability of the nonlinear travelling front, thus explaining how nonlinear systems can exhibit slower spreading that their linearization in a robust fashion
Modeling traveling-wave Thomson scattering using PIConGPU
Energy Technology Data Exchange (ETDEWEB)
Debus, Alexander; Schramm, Ulrich; Cowan, Thomas; Bussmann, Michael [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Steiniger, Klaus; Pausch, Richard; Huebl, Axel [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden (Germany)
2016-07-01
Traveling-wave Thomson scattering (TWTS) laser pulses are pulse-front tilted and dispersion corrected beams that enable all-optical free-electron lasers (OFELs) up to the hard X-ray range. Electrons in such a side-scattering geometry experience the TWTS laser field as a continuous plane wave over centimeter to meter interaction lengths. After briefly discussing which OFEL scenarios are currently numerically accessible, we detail implementation and tests of TWTS beams within PIConGPU (3D-PIC code) and show how numerical dispersion and boundary effects are kept under control.
Pre-travel advice seeking from GPs by travellers with chronic illness seen at a travel clinic.
Gagneux-Brunon, Amandine; Andrillat, Carole; Fouilloux, Pascale; Daoud, Fatiha; Defontaine, Christiane; Charles, Rodolphe; Lucht, Frédéric; Botelho-Nevers, Elisabeth
2016-03-01
Travellers are ageing and frequently report chronic illness. Pre-travel health advice is crucial, particularly in this subgroup, and general practitioners (GPs) are first in line for treatment adjustment before departure. Our aim is to evaluate pre-travel health advice seeking from GPs by travellers with chronic illness seen at a travel clinic. A cross-sectional observational survey using a questionnaire was conducted between August 2013 and July 2014 in travellers attending the travel medicine clinic of a tertiary university hospital in France. During the study, 2019 travellers were included. Mean age was 39.4 years (±18.8). Three hundred and ninety-one (19.4%) travellers reported a history of a chronic illness. Arterial hypertension and diabetes mellitus were the most frequently reported illnesses, affecting, respectively, 168 (8.3%) travellers and 102 (5.1%). Hajj pilgrims were more likely to report a history of chronic illness than other travellers. Only 810 (40.1%) travellers sought pre-travel advice from their GP. Six hundred and fifty-two (40.1%) healthy travellers and 158 (40.5%) travellers reporting chronic illness sought pre-travel advice from their GP (P = 0.96). Travellers with a history of chronic illness do not seek pre-travel health advice from their GP more frequently than healthy travellers. Travel health specialists are generally not the best practitioners to manage the care of underlying medical conditions presenting risks during travel. However, GPs offer continuity and disease management expertise to improve the specificity of pre-travel planning. Thus, ongoing collaboration between the traveller, GP and travel health specialist is likely to yield the best outcomes. © International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.
Carlson Wagonlit Travel is moving
2013-01-01
The renovation of the Main Building continues! Because of this, Carlson Wagonlit Travel will move from building 62 to building 510 on 4 October and the agency will be closed in the afternoon. An emergency service will be organised for official travels only. Phone: 022 799 75 73 & 022 799 75 78 / e-mail: cern@carlsonwagonlit.ch
2003-11-01
The Thanksgiving and Christmas/New Years holiday periods are among the busiest long-distance travel periods of the year. During the 6-day Thanksgiving travel period, the number of long-distance trips (to and from a destination 50 miles or more awa...
Centers for Disease Control (CDC) Podcasts
Each year over 55,000 people die because of rabies, mostly from being bitten by rabid dogs. Over half of all rabies infections occur in children under the age of 15 who live in developing countries, but travelers are not immune. This podcast discusses some of the activities that put travelers at risk for rabies and describes ways to prevent infection.
Travel and Adult Transformative Learning
Lindstrom, Steven K.
2011-01-01
This phenomenological research study examines the lived experience of individual adult transformation in the context of travel. Adults throughout history have experienced profound personal and perception changes as a result of significant travel events. Transformative learning occurs through experience, crisis, and reflection, all of which are…
2003-10-01
Americans make more than 405 million long-distance business trips per year, : accounting for 16% of all long-distance travel, according to a : preliminary analysis of the National Household Travel Survey (NHTS). : Conducted from 2001 to 2002, the NHT...
49 CFR 229.55 - Piston travel.
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 229.55 Section 229.55... Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance when... piston travel may not exceed 11/2 inches less than the total possible piston travel. The total possible...
Travel time variability and rational inattention
DEFF Research Database (Denmark)
Fosgerau, Mogens; Jiang, Gege
2017-01-01
This paper sets up a rational inattention model for the choice of departure time for a traveler facing random travel time. The traveler chooses how much information to acquire about the travel time out-come before choosing departure time. This reduces the cost of travel time variability compared...
Monitoring Travel Time Reliability on Freeways
Tu, Huizhao
2008-01-01
Travel time and travel time reliability are important attributes of a trip. The current measures of reliability have in common that in general they all relate to the variability of travel times. However, travel time reliability does not only rely on variability but also on the stability of travel
Blocking-resistant communication through domain fronting
Directory of Open Access Journals (Sweden)
Fifield David
2015-06-01
Full Text Available We describe “domain fronting,” a versatile censorship circumvention technique that hides the remote endpoint of a communication. Domain fronting works at the application layer, using HTTPS, to communicate with a forbidden host while appearing to communicate with some other host, permitted by the censor. The key idea is the use of different domain names at different layers of communication. One domain appears on the “outside” of an HTTPS request—in the DNS request and TLS Server Name Indication—while another domain appears on the “inside”—in the HTTP Host header, invisible to the censor under HTTPS encryption. A censor, unable to distinguish fronted and nonfronted traffic to a domain, must choose between allowing circumvention traffic and blocking the domain entirely, which results in expensive collateral damage. Domain fronting is easy to deploy and use and does not require special cooperation by network intermediaries. We identify a number of hard-to-block web services, such as content delivery networks, that support domain-fronted connections and are useful for censorship circumvention. Domain fronting, in various forms, is now a circumvention workhorse. We describe several months of deployment experience in the Tor, Lantern, and Psiphon circumvention systems, whose domain-fronting transports now connect thousands of users daily and transfer many terabytes per month.
Level Diagrams analysis of Pareto Front for multiobjective system redundancy allocation
International Nuclear Information System (INIS)
Zio, E.; Bazzo, R.
2011-01-01
Reliability-based and risk-informed design, operation, maintenance and regulation lead to multiobjective (multicriteria) optimization problems. In this context, the Pareto Front and Set found in a multiobjective optimality search provide a family of solutions among which the decision maker has to look for the best choice according to his or her preferences. Efficient visualization techniques for Pareto Front and Set analyses are needed for helping decision makers in the selection task. In this paper, we consider the multiobjective optimization of system redundancy allocation and use the recently introduced Level Diagrams technique for graphically representing the resulting Pareto Front and Set. Each objective and decision variable is represented on separate diagrams where the points of the Pareto Front and Set are positioned according to their proximity to ideally optimal points, as measured by a metric of normalized objective values. All diagrams are synchronized across all objectives and decision variables. On the basis of the analysis of the Level Diagrams, we introduce a procedure for reducing the number of solutions in the Pareto Front; from the reduced set of solutions, the decision maker can more easily identify his or her preferred solution.
Travelling Waves in Hybrid Chemotaxis Models
Franz, Benjamin
2013-12-18
Hybrid models of chemotaxis combine agent-based models of cells with partial differential equation models of extracellular chemical signals. In this paper, travelling wave properties of hybrid models of bacterial chemotaxis are investigated. Bacteria are modelled using an agent-based (individual-based) approach with internal dynamics describing signal transduction. In addition to the chemotactic behaviour of the bacteria, the individual-based model also includes cell proliferation and death. Cells consume the extracellular nutrient field (chemoattractant), which is modelled using a partial differential equation. Mesoscopic and macroscopic equations representing the behaviour of the hybrid model are derived and the existence of travelling wave solutions for these models is established. It is shown that cell proliferation is necessary for the existence of non-transient (stationary) travelling waves in hybrid models. Additionally, a numerical comparison between the wave speeds of the continuum models and the hybrid models shows good agreement in the case of weak chemotaxis and qualitative agreement for the strong chemotaxis case. In the case of slow cell adaptation, we detect oscillating behaviour of the wave, which cannot be explained by mean-field approximations. © 2013 Society for Mathematical Biology.
Characterizing Ion Flows Across a Dipolarization Front
Arnold, H.; Drake, J. F.; Swisdak, M.
2017-12-01
In light of the Magnetospheric Multiscale Mission (MMS) moving to study predominately symmetric magnetic reconnection in the Earth's magnetotail, it is of interest to investigate various methods for determining the relative location of the satellites with respect to the x line or a dipolarization front. We use a 2.5 dimensional PIC simulation to explore the dependence of various characteristics of a front, or flux bundle, on the width of the front in the dawn-dusk direction. In particular, we characterize the ion flow in the x-GSM direction across the front. We find a linear relationship between the width of a front, w, and the maximum velocity of the ion flow in the x-GSM direction, Vxi, for small widths: Vxi/VA=w/di*1/2*(mVA2)/Ti*Bz/Bxwhere m, VA, di, Ti, Bz, and Bx are the ion mass, upstream Alfven speed, ion inertial length, ion temperature, and magnetic fields in the z-GSM and x-GSM directions respectively. However, once the width reaches around 5 di, the relationship gradually approaches the well-known theoretical limit for ion flows, the upstream Alfven speed. Furthermore, we note that there is a reversal in the Hall magnetic field near the current sheet on the positive y-GSM side of the front. This reversal is most likely due to conservation of momentum in the y-GSM direction as the ions accelerate towards the x-GSM direction. This indicates that while the ions are primarily energized in the x-GSM direction by the front, they transfer energy to the electromagnetic fields in the y-GSM direction. The former energy transfer is greater than the latter, but the reversal of the Hall magnetic field drags the frozen-in electrons along with it outside of the front. These simulations should better able researchers to determine the relative location of a satellite crossing a dipolarization front.
Managing Controversies in the Fuzzy Front End
DEFF Research Database (Denmark)
Christiansen, John K.; Gasparin, Marta
2016-01-01
This research investigates the controversies that emerge in the fuzzy front end (FFE) and how they are closed so the innovation process can move on. The fuzzy front has been characterized in the literature as a very critical phase, but controversies in the FFE have not been studied before....... The analysis investigates the microprocesses around the controversies that emerge during the fuzzy front end of four products. Five different types of controversies are identified: profit, production, design, brand and customers/market. Each controversy represents a threat, but also an opportunity to search...
Vacillations induced by interference of stationary and traveling planetary waves
Salby, Murry L.; Garcia, Rolando R.
1987-01-01
The interference pattern produced when a traveling planetary wave propagates over a stationary forced wave is explored, examining the interference signature in a variety of diagnostics. The wave field is first restricted to a diatomic spectrum consisting of two components: a single stationary wave and a single monochromatic traveling wave. A simple barotropic normal mode propagating over a simple stationary plane wave is considered, and closed form solutions are obtained. The wave fields are then restricted spatially, providing more realistic structures without sacrificing the advantages of an analytical solution. Both stationary and traveling wave fields are calculated numerically with the linearized Primitive Equations in a realistic basic state. The mean flow reaction to the fluctuating eddy forcing which results from interference is derived. Synoptic geopotential behavior corresponding to the combined wave and mean flow fields is presented, and the synoptic signature in potential vorticity on isentropic surfaces is examined.
SPD very front end electronics
International Nuclear Information System (INIS)
Luengo, S.; Gascon, D.; Comerma, A.; Garrido, L.; Riera, J.; Tortella, S.; Vilasis, X.
2006-01-01
The Scintillator Pad Detector (SPD) is part of the LHCb calorimetry system [D. Breton, The front-end electronics for LHCb calorimeters, Tenth International Conference on Calorimetry in Particle Physics, CALOR, Pasadena, 2002] that provides high-energy hadron, electron and photon candidates for the first level trigger. The SPD is designed to distinguish electrons from photons. It consists of a plastic scintillator layer, divided into about 6000 cells of different size to obtain better granularity near the beam [S. Amato, et al., LHCb technical design report, CERN/LHCC/2000-0036, 2000]. Charged particles will produce, and photons will not, ionization in the scintillator. This ionization generates a light pulse that is collected by a WaveLength Shifting (WLS) fiber that is coiled inside the scintillator cell. The light is transmitted through a clear fiber to the readout system that is placed at the periphery of the detector. Due to space constraints, and in order to reduce costs, these 6000 cells are divided in groups using a MAPMT [Z. Ajaltouni, et al., Nucl. Instr. and Meth. A 504 (2003) 9] of 64 channels that provides information to the VFE readout electronics. The SPD signal has rather large statistical fluctuations because of the low number (20-30) of photoelectrons per MIP. Therefore the signal is integrated over the whole bunch crossing length of 25 ns in order to have the maximum value. Since in average about 85% of the SPD signal is within 25 ns, 15% of a sample is subtracted from the following one using an operational amplifier. The SPD VFE readout system that will be presented consists of the following components. A specific ASIC [D. Gascon, et al., Discriminator ASIC for the VFE SPD of the LHCb Calorimeter, LHCB Technical Note, LHCB 2004-xx] integrates the signal, makes the signal-tail subtraction, and compares the level obtained to a programmable threshold (to distinguish electrons from photons). A FPGA programmes the ASIC threshold and the value for
Propagation of transition fronts in nonlinear chains with non-degenerate on-site potentials
Shiroky, I. B.; Gendelman, O. V.
2018-02-01
We address the problem of transition front propagation in chains with a bi-stable nondegenerate on-site potential and a nonlinear gradient coupling. For generic nonlinear coupling, one encounters a special regime of transitions, characterized by extremely narrow fronts, far supersonic velocities of the front propagation, and long waves in the oscillatory tail. This regime can be qualitatively associated with a shock wave. The front propagation can be described with the help of a simple reduced-order model; the latter delivers a kinetic law, which is almost not sensitive to the fine details of the on-site potential. Besides, it is possible to predict all main characteristics of the transition front, including its velocity, as well as the frequency and the amplitude of the oscillatory tail. Numerical results are in good agreement with the analytical predictions. The suggested approach allows one to consider the effects of an external pre-load, the next-nearest-neighbor coupling and the on-site damping. When the damping is moderate, it is possible to consider the shock propagation in the damped chain as a perturbation of the undamped dynamics. This approach yields reasonable predictions. When the damping is high, the transition front enters a completely different asymptotic regime of a subsonic kink. The gradient nonlinearity generically turns negligible, and the propagating front converges to the regime described by a simple exact solution for a continuous model with linear coupling.
International Development Research Centre Governor Travel Policy
International Development Research Centre (IDRC) Digital Library (Canada)
André Lavoie
business. Governors are required to travel to conduct IDRC business, attend ... of Governors, liaise with Centre management, and perform specific representational functions on ..... Travel between Points of Origin and Destination - Air Travel.
Improving Polyp Detection Algorithms for CT Colonography: Pareto Front Approach.
Huang, Adam; Li, Jiang; Summers, Ronald M; Petrick, Nicholas; Hara, Amy K
2010-03-21
We investigated a Pareto front approach to improving polyp detection algorithms for CT colonography (CTC). A dataset of 56 CTC colon surfaces with 87 proven positive detections of 53 polyps sized 4 to 60 mm was used to evaluate the performance of a one-step and a two-step curvature-based region growing algorithm. The algorithmic performance was statistically evaluated and compared based on the Pareto optimal solutions from 20 experiments by evolutionary algorithms. The false positive rate was lower (pPareto optimization process can effectively help in fine-tuning and redesigning polyp detection algorithms.
Eskew, Matthew W.; Harrison, Jason; Simoyi, Reuben H.
2016-11-01
Oxidation reactions of thiourea by chlorite in a Hele-Shaw cell are excitable, autocatalytic, exothermic, and generate a lateral instability upon being triggered by the autocatalyst. Reagent concentrations used to develop convective instabilities delivered a temperature jump at the wave front of 2.1 K. The reaction zone was 2 mm and due to normal cooling after the wave front, this generated a spike rather than the standard well-studied front propagation. The reaction front has solutal and thermal contributions to density changes that act in opposite directions due to the existence of a positive isothermal density change in the reaction. The competition between these effects generates thermal plumes. The fascinating feature of this system is the coexistence of plumes and fingering in the same solution which alternate in frequency as the front propagates, generating hot and cold spots within the Hele-Shaw cell, and subsequently spatiotemporal inhomogeneities. The small ΔT at the wave front generated thermocapillary convection which competed effectively with thermogravitational forces at low Eötvös Numbers. A simplified reaction-diffusion-convection model was derived for the system. Plume formation is heavily dependent on boundary effects from the cell dimensions. This work was supported by Grant No. CHE-1056366 from the NSF and a Research Professor Grant from the University of KwaZulu-Natal.
On the infiltration of a liquid front in an unsaturated, fractured porous medium
International Nuclear Information System (INIS)
Nitao, J.; Buscheck, T.
1989-08-01
The unsaturated zone at Yucca Mountain, Nevada, is currently under scientific investigation as a proposed site for the permanent storage of high-level nuclear waste. A deeper understanding of fracture-matrix interaction needed for the prediction of water movement around an in the repository. We show that the liquid front movement can be classified into physically interpretable, distinctive flow regimes. Asymptotic solutions for the front movement are given for each flow period and comparisons with numerical solutions are made. In addition to applications in nuclear waste storage, the results of our study is relevant to hazardous waste disposal, petroleum recovery, and flow in soil macropores. 17 refs., 13 figs., 6 tabs
On the movement of a liquid front in an unsaturated, fractured porous medium, Part 1
International Nuclear Information System (INIS)
Nitao, J.J.; Buscheck, T.A.
1989-06-01
The primary aim of this paper is to present approximate analytical solutions of the fracture flow which gives the position of the liquid fracture front as a function of time. These solutions demonstrate that the liquid movement in the fracture can be classified into distinctive time periods, or flow regimes. It is also shown that when plotted versus time using a log-log scale, the liquid fracture front position asymptotically approaches a series of line segments. Two-dimensional numerical simulations were run utilizing input data applicable to the densely welded, fractured tuff found at Yucca Mountain in order to confirm these observations. 19 refs., 15 figs., 8 tabs
Calculation of groundwater travel time
International Nuclear Information System (INIS)
Arnett, R.C.; Sagar, B.; Baca, R.G.
1984-12-01
Pre-waste-emplacement groundwater travel time is one indicator of the isolation capability of the geologic system surrounding a repository. Two distinct modeling approaches exist for prediction of groundwater flow paths and travel times from the repository location to the designated accessible environment boundary. These two approaches are: (1) the deterministic approach which calculates a single value prediction of groundwater travel time based on average values for input parameters and (2) the stochastic approach which yields a distribution of possible groundwater travel times as a function of the nature and magnitude of uncertainties in the model inputs. The purposes of this report are to (1) document the theoretical (i.e., mathematical) basis used to calculate groundwater pathlines and travel times in a basalt system, (2) outline limitations and ranges of applicability of the deterministic modeling approach, and (3) explain the motivation for the use of the stochastic modeling approach currently being used to predict groundwater pathlines and travel times for the Hanford Site. Example calculations of groundwater travel times are presented to highlight and compare the differences between the deterministic and stochastic modeling approaches. 28 refs
On Traveling Waves in Lattices: The Case of Riccati Lattices
Dimitrova, Zlatinka
2012-09-01
The method of simplest equation is applied for analysis of a class of lattices described by differential-difference equations that admit traveling-wave solutions constructed on the basis of the solution of the Riccati equation. We denote such lattices as Riccati lattices. We search for Riccati lattices within two classes of lattices: generalized Lotka-Volterra lattices and generalized Holling lattices. We show that from the class of generalized Lotka-Volterra lattices only the Wadati lattice belongs to the class of Riccati lattices. Opposite to this many lattices from the Holling class are Riccati lattices. We construct exact traveling wave solutions on the basis of the solution of Riccati equation for three members of the class of generalized Holling lattices.
Experienced travel time prediction for congested freeways
Yildirimoglu, Mehmet; Geroliminis, Nikolaos
2013-01-01
Travel time is an important performance measure for transportation systems, and dissemination of travel time information can help travelers make reliable travel decisions such as route choice or departure time. Since the traffic data collected in real time reflects the past or current conditions on the roadway, a predictive travel time methodology should be used to obtain the information to be disseminated. However, an important part of the literature either uses instantaneous travel time ass...
Instability of traveling waves of the convective-diffusive Cahn-Hilliard equation
International Nuclear Information System (INIS)
Gao Hongjun; Liu Changchun
2004-01-01
In this paper we study the instability of the traveling waves of the convective-diffusive Cahn-Hilliard equation. We prove that it is nonlinearly unstable under H 2 perturbations, for some traveling wave solution that is asymptotic to a constant as x→∞
On Front Slope Stability of Berm Breakwaters
DEFF Research Database (Denmark)
Burcharth, Hans F.
2013-01-01
The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison...... with the reshaping of a large Norwegian breakwater exposed to the North Sea waves. As a motivation for applying the Van der Meer formula a discussion of design parameters related to berm breakwater stability formulae is given. Comparisons of front erosion predicted by the use of the Van der Meer formula with model...... test results including tests presented in Sigurdarson and Van der Meer (2011) are discussed. A proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope, relative berm height...
The extended (G/G)-expansion method and travelling wave ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 6. The extended (′/)-expansion method and travelling wave solutions for the perturbed nonlinear Schrödinger's equation with Kerr law nonlinearity. Zaiyun Zhang Jianhua Huang Juan Zhong Sha-Sha Dou Jiao Liu Dan Peng Ting Gao. Research Articles ...
Topological horseshoes in travelling waves of discretized nonlinear wave equations
International Nuclear Information System (INIS)
Chen, Yi-Chiuan; Chen, Shyan-Shiou; Yuan, Juan-Ming
2014-01-01
Applying the concept of anti-integrable limit to coupled map lattices originated from space-time discretized nonlinear wave equations, we show that there exist topological horseshoes in the phase space formed by the initial states of travelling wave solutions. In particular, the coupled map lattices display spatio-temporal chaos on the horseshoes
Topological horseshoes in travelling waves of discretized nonlinear wave equations
Energy Technology Data Exchange (ETDEWEB)
Chen, Yi-Chiuan, E-mail: YCChen@math.sinica.edu.tw [Institute of Mathematics, Academia Sinica, Taipei 10617, Taiwan (China); Chen, Shyan-Shiou, E-mail: sschen@ntnu.edu.tw [Department of Mathematics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Yuan, Juan-Ming, E-mail: jmyuan@pu.edu.tw [Department of Financial and Computational Mathematics, Providence University, Shalu, Taichung 43301, Taiwan (China)
2014-04-15
Applying the concept of anti-integrable limit to coupled map lattices originated from space-time discretized nonlinear wave equations, we show that there exist topological horseshoes in the phase space formed by the initial states of travelling wave solutions. In particular, the coupled map lattices display spatio-temporal chaos on the horseshoes.
Development of the PEBLebl Traveling Salesman Problem Computerized Testbed
Mueller, Shane T.; Perelman, Brandon S.; Tan, Yin Yin; Thanasuan, Kejkaew
2015-01-01
The traveling salesman problem (TSP) is a combinatorial optimization problem that requires finding the shortest path through a set of points ("cities") that returns to the starting point. Because humans provide heuristic near-optimal solutions to Euclidean versions of the problem, it has sometimes been used to investigate human visual…
Fast and Efficient Discrimination of Traveling Salesperson Problem Stimulus Difficulty
Dry, Matthew J.; Fontaine, Elizabeth L.
2014-01-01
The Traveling Salesperson Problem (TSP) is a computationally difficult combinatorial optimization problem. In spite of its relative difficulty, human solvers are able to generate close-to-optimal solutions in a close-to-linear time frame, and it has been suggested that this is due to the visual system's inherent sensitivity to certain geometric…
A parallel 2-opt algorithm for the traveling salesman problem
Verhoeven, M.G.A.; Aarts, E.H.L.; Swinkels, P.C.J.
1995-01-01
We present a scalable parallel local search algorithm based on data parallelism. The concept of distributed neighborhood structures is introduced, and applied to the Traveling Salesman Problem (TSP). Our parallel local search algorithm finds the same quality solutions as the classical 2-opt
Travelling solitons in the parametrically driven nonlinear Schroedinger equation
International Nuclear Information System (INIS)
Barashenkov, I.V.; Zemlyanaya, E.V.; Baer, M.
2000-01-01
We show that the parametrically driven nonlinear Schroedinger equation has wide classes of travelling soliton solutions, some of which are stable. For small driving strengths stable nonpropagating and moving solitons co-exist while strongly forced solitons can only be stable when moving sufficiently fast
Front end designs for the 7-GeV advanced photon source
International Nuclear Information System (INIS)
Shu, D.; Barraza, J.; Sanchez, T.; Nielsen, R.W.; Collins, J.T.; Kuzay, T.M.
1992-01-01
The conceptual designs for the insertion device (ID) and bending magnet (BM) front ends have been completed for the 7-GeV Advanced Photon Source (APS) under construction at Argonne National Laboratory. These designs satisfy the generic front end functions. However, the high power and high heat fluxes imposed by the X-ray sources of the 7-GeV APS have presented various design engineering challenges for the front end. Consideration of such challenges and their solutions have led to novel and advanced features including modularized systems, enhanced heat transfer concepts in the fixed mask and the photon shutter designs, a radiation safety philosophy based on multiple photon shutters for a fail-safe operation, a sub-micron resolution beam position monitor for beam monitoring and ring feedback information, and minimal beam filtering concepts to deliver maximized beam power and spectra to the experimenters. The criteria and special features of the front end design are discussed in this paper
PTRACK: A particle tracking program for evaluation travel path/travel time uncertainties
International Nuclear Information System (INIS)
Thompson, B.M.; Campbell, J.E.; Longsine, D.E.
1987-12-01
PTRACK is a model which tracks the path of a radionuclide particle released from a nuclear waste repository into a ground-water flow system in a two-dimensional representation of stratified geologic medium. The code calculates the time required for the particle to travel from the release point (the edge of the disturbed zone) to the specified horizontal or vertical boundary (the accessible environment). The physical properties of the geologic setting and the ground-water flow system can be treated as fixed values or as random variables sampled from their respective probability distributions. In the latter case, PTRACK assigns a sampled value for each parameter and tracks a particle for this trial (realization) of the system. Repeated realizations allow the effects of parameter uncertainty on travel paths/travel times to be quantified. The code can also calculate partial correlation coefficients between dependent variables and independent variables, which are useful in identifying important independent variables. This documentation describes the mathematical basis for the model, the algorithms and solution techniques used, and the computer code design. It also contains a detailed user's manual. The implementation of PTRACK is verified with several systems for which solutions have been calculated by hand. The integration of PTRACK with a Latin hypercube sampling (LHS) code is also discussed, although other sampling methods can be employed in place of LHS. 11 refs., 14 figs., 22 tabs
Hern, W M
1993-01-01
honor those who advanced the cause of women's rights. They honored the physician who had to shout over hecklers to make his remarks heard. After a year of operation, the physician encountered differences with the Board of Directors of the clinic. Soon after that, he resigned and opened his own clinic with a bank loan of $7000. Within 4 years, his clinic had expanded, and he purchased its building. The harassment from antiabortion protesters continued, with broken windows, pickets, and, in February 1988, bullets fired through the front windows of the waiting room. This necessitated the installation of bullet-proof glass and a security system which cost $17,000. As of March 1, 1993, there had been 1285 acts of violence towards abortion clinics, which led to the destruction of more than 100. On March 10 of that year, a physician who performed abortions in Florida was gunned down by an anti-abortion protestor. People who provide abortions hope for legal protection and respect for their civil liberties, but they will continue to provide this service even if conditions do not improve.
GH Travel & Mission Support System
US Agency for International Development — HTRAMS is a travel data collection system for GH that collects information on both the basic details of an employee's trips (destination, length, purpose, etc.) and...
PPL Travel & Mission Support System
US Agency for International Development — PTRAMS is a travel data collection system for PPL that collects information on both the basic details of an employee's trips (destination, length, purpose, etc.) and...
Traveler's Health: Avoid Bug Bites
... Safety Road Safety - 8 Steps MERS Health Advisory poster MERS Pictogram CDC Guide for Healthy Travel Website ... other accommodations that are air conditioned or have good window and door screens so bugs can’t ...
Travelers' Health: Injuries and Safety
... Safety Road Safety - 8 Steps MERS Health Advisory poster MERS Pictogram CDC Guide for Healthy Travel Website ... possible, fly on larger planes (>30 seats), in good weather, during the daylight hours, and with experienced ...
DCHA Travel & Mission Support System
US Agency for International Development — DTRAMS is a travel data collection system for DCHA that collects information on both the basic details of an employee's trips (destination, length, purpose, etc.)...
Transmedia storytelling on travel stories
Directory of Open Access Journals (Sweden)
Adolfo Baltar Moreno
2016-01-01
Full Text Available Travel stories form part of a great tradition inside Western Culture which has served historically to describe, to understand and to imagine other cul - tures and communities, far or near, being constituted into a real narra - tive genre. This type of story has been and is a reflection of the perception of the world based on the imaginary worlds created by the travelling narrators. How do modern authors of travel stories take advantage of the opportunities offered by transmedia storytelling? The present article explores the potential of these types of stories as a privileged object of study for transmedia storytelling studies, from the analysis of a sample of 80 narrative productions based on experiences of travel and presented in diverse editions of the Festival Le Grand Bivouac (France. It also shows the existence of a new contemporary trend inside this narrative form that transcends its literary nature.
Bacterial infec tions in travellers
African Journals Online (AJOL)
namely bacterial causes of travellers' diarrhoea and skin infections, as well as .... Vaccination: protective efficacy against typhoid may be overcome by ingesting a high bacterial load. Vaccine ..... preparation such as cream sauce. Only after ...
Travel time estimation using Bluetooth.
2015-06-01
The objective of this study was to investigate the feasibility of using a Bluetooth Probe Detection System (BPDS) to : estimate travel time in an urban area. Specifically, the study investigated the possibility of measuring overall congestion, the : ...
Travel reliability inventory for Chicago.
2013-04-01
The overarching goal of this research project is to enable state DOTs to document and monitor the reliability performance : of their highway networks. To this end, a computer tool, TRIC, was developed to produce travel reliability inventories from : ...
Radiation hazard when we travel?
International Nuclear Information System (INIS)
Muhamat Omar
2003-01-01
It is apparent that we are all exposed to natural radiation while travelling from one place to another. Air and sea travelers receive the highest and the lowest radiation dose respectively. The doses received by on-land travelers are generally low although some places near the mineral and slag heaps show high radiation levels. With proper management and enforcement, the contribution from these heaps on the roadsides can be easily removed. The other important radiation source is the tunnels built through granite rocks. However, this is more concern to the construction workers rather than to travelers. Thus, the authors are of the opinion that it is worth to look into the radiation exposures to the tunnel construction workers
DEFF Research Database (Denmark)
Christensen, Linda
2014-01-01
This paper presents an overview of the Dane’s long distance travel. It is a part of the Drivers and Limits project about long distance travel. Long distance travel is in the project defined as infrequent travel with overnight stay. Danes 15-85 years-old travel in average 5.5 long distance travel...... per year og which a third is for international destinations, a third is for domestic second homes and a third are other domestic trips. However, 87% of the kilometres are for international destinations and only 4% are for domestic second homes. Travel activity is very uneven distributed with only half...... of the population having had a journey during the last three month. At the other hand 60% have travelled internationally during the last year and only 2% have never travelled abroad. The paper presents among other things how the travel activity is distributed on travel purpose and mode and how the mode choice...
International Nuclear Information System (INIS)
Bentley, H.; Grisak, G.
1985-01-01
The Containment and Isolation Working Group considered issues related to the postclosure behavior of repositories in crystalline rock. This working group was further divided into subgroups to consider the progress since the 1978 GAIN Symposium and identify research needs in the individual areas of regional ground-water flow, ground-water travel time, fractional release, and cumulative release. The analysis and findings of the Ground-Water Travel Time Subgroup are presented
International Nuclear Information System (INIS)
Pfarr, J.
1981-01-01
An analysis is presented of the motion of test particles in Goedel's universe. Both geodesical and nongeodesical motions are considered; the accelerations for nongeodesical motions are given. Examples for closed timelike world lines are shown and the dynamical conditions for time travel in Goedel's space-time are discussed. It is shown that these conditions alone do not suffice to exclude time travel in Goedel's space-time. (author)
Sequentially pulsed traveling wave accelerator
Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA
2009-08-18
A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.
Ma, Xiao Wei; Pell, Lisa G; Akseer, Nadia; Khan, Sarah; Lam, Ray E; Louch, Debra; Science, Michelle; Morris, Shaun K
2016-01-01
International travelers are susceptible to a wide spectrum of travel related morbidities. Despite rising number of international travelers in Canada, the demographics, risk profiles, and preventative strategies of high-risk traveler groups, including pediatric travelers visiting friends and relatives (VFRs) are not well described. A descriptive analysis was conducted on pre-travel consultations completed between January 2013 and August 2014 at a large pediatric tertiary care center in Toronto, Canada. Data on demographics, travel characteristics, and pre-travel interventions were extracted from 370 pre-travel consultations. Results were compared between all VFR and non-VFR travelers, as well as between children traveling to visit friends and relatives, for vacation, and for education and/or volunteer purposes. Forty-eight percent of consultations were for children travel to visit friends and/or relatives than for other purposes (29% vs 9%, p travel for >28 days than children traveling for vacation (43% vs 1%, p traveling for education/volunteer purposes (43% vs 21%, p = 0.03). Around half of cVFRs traveled to destinations in Asia (51%). The majority stayed with locals, friends and/or relatives (85%), and nearly all traveled to urban destinations (98%). The most prescribed interventions for children were azithromycin (84%), Dukoral (66%), and the hepatitis A vaccine (60%). Atovaquone/proguanil was the most commonly prescribed antimalarial for children. Children that travel to visit friends and relatives represent a unique travel group and may require specific considerations during pre-travel preparations. Our findings can help develop targeted pre-travel strategies for children VFRs. Copyright © 2015 Elsevier Ltd. All rights reserved.
Coghlan, A; Hoad, V C; Seed, C R; Flower, R Lp; Harley, R J; Herbert, D; Faddy, H M
2018-01-01
International travel assists spread of infectious pathogens. Australians regularly travel to South-eastern Asia and the isles of the South Pacific, where they may become infected with infectious agents, such as dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) viruses that pose a potential risk to transfusion safety. In Australia, donors are temporarily restricted from donating for fresh component manufacture following travel to many countries, including those in this study. We aimed to estimate the unmitigated transfusion-transmission (TT) risk from donors travelling internationally to areas affected by emerging infectious diseases. We used the European Up-Front Risk Assessment Tool, with travel and notification data, to estimate the TT risk from donors travelling to areas affected by disease outbreaks: Fiji (DENV), Bali (DENV), Phuket (DENV), Indonesia (CHIKV) and French Polynesia (ZIKV). We predict minimal risk from travel, with the annual unmitigated risk of an infected component being released varying from 1 in 1·43 million to disease outbreak areas to source plasma collection provides a simple and effective risk management approach. © 2017 International Society of Blood Transfusion.
Intercity Travel Demand Analysis Model
Directory of Open Access Journals (Sweden)
Ming Lu
2014-01-01
Full Text Available It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model of main mode choice and access mode choice. At last, an integrated multilevel nested logit model structure system was built. The model system includes trip generation, destination choice, and mode-route choice based on multinomial logit model, and it achieved linkage and feedback of each part through logsum variable. This model was applied in Shenzhen intercity railway passenger demand forecast in 2010 as a case study. As a result, the forecast results were consistent with the actuality. The model's correctness and feasibility were verified.
Infectious Risks of Traveling Abroad.
Chen, Lin H; Blair, Barbra M
2015-08-01
A popular leisure activity, international travel can be associated with some infections. The most common travel-related illnesses appear to be gastrointestinal, dermatologic, respiratory, and systemic febrile syndromes. The pretravel medical consultation includes immunizations, malaria chemoprophylaxis, self-treatment for traveler's diarrhea, and advice on the prevention of a myriad of other infectious causes including dengue, chikungunya, rickettsiosis, leptospirosis, schistosomiasis, and strongyloidiasis. Travel to locations experiencing outbreaks such as Ebola virus disease, Middle East respiratory syndrome, avian influenza, and chikungunya call for specific alerts on preventive strategies. After travel, evaluation of an ill traveler must explore details of exposure, including destinations visited; activities; ingestion of contaminated food or drinks; contact with vectors, animals, fresh water, or blood and body fluids; and other potential exposures. Knowledge of the geographic distribution of infectious diseases is important in generating the differential diagnoses and testing accordingly. Empiric treatment is sometimes necessary when suspicion of a certain diagnosis is strong and confirmatory tests are delayed or lacking, particularly for infections that are rapidly progressive (for example, malaria) or for which timing of testing is prolonged (such as leptospirosis).
Pareto fronts in clinical practice for pinnacle.
Janssen, Tomas; van Kesteren, Zdenko; Franssen, Gijs; Damen, Eugène; van Vliet, Corine
2013-03-01
Our aim was to develop a framework to objectively perform treatment planning studies using Pareto fronts. The Pareto front represents all optimal possible tradeoffs among several conflicting criteria and is an ideal tool with which to study the possibilities of a given treatment technique. The framework should require minimal user interaction and should resemble and be applicable to daily clinical practice. To generate the Pareto fronts, we used the native scripting language of Pinnacle(3) (Philips Healthcare, Andover, MA). The framework generates thousands of plans automatically from which the Pareto front is generated. As an example, the framework is applied to compare intensity modulated radiation therapy (IMRT) with volumetric modulated arc therapy (VMAT) for prostate cancer patients. For each patient and each technique, 3000 plans are generated, resulting in a total of 60,000 plans. The comparison is based on 5-dimensional Pareto fronts. Generating 3000 plans for 10 patients in parallel requires on average 96 h for IMRT and 483 hours for VMAT. Using VMAT, compared to IMRT, the maximum dose of the boost PTV was reduced by 0.4 Gy (P=.074), the mean dose in the anal sphincter by 1.6 Gy (P=.055), the conformity index of the 95% isodose (CI(95%)) by 0.02 (P=.005), and the rectal wall V(65 Gy) by 1.1% (P=.008). We showed the feasibility of automatically generating Pareto fronts with Pinnacle(3). Pareto fronts provide a valuable tool for performing objective comparative treatment planning studies. We compared VMAT with IMRT in prostate patients and found VMAT had a dosimetric advantage over IMRT. Copyright © 2013 Elsevier Inc. All rights reserved.
Pareto Fronts in Clinical Practice for Pinnacle
International Nuclear Information System (INIS)
Janssen, Tomas; Kesteren, Zdenko van; Franssen, Gijs; Damen, Eugène; Vliet, Corine van
2013-01-01
Purpose: Our aim was to develop a framework to objectively perform treatment planning studies using Pareto fronts. The Pareto front represents all optimal possible tradeoffs among several conflicting criteria and is an ideal tool with which to study the possibilities of a given treatment technique. The framework should require minimal user interaction and should resemble and be applicable to daily clinical practice. Methods and Materials: To generate the Pareto fronts, we used the native scripting language of Pinnacle 3 (Philips Healthcare, Andover, MA). The framework generates thousands of plans automatically from which the Pareto front is generated. As an example, the framework is applied to compare intensity modulated radiation therapy (IMRT) with volumetric modulated arc therapy (VMAT) for prostate cancer patients. For each patient and each technique, 3000 plans are generated, resulting in a total of 60,000 plans. The comparison is based on 5-dimensional Pareto fronts. Results: Generating 3000 plans for 10 patients in parallel requires on average 96 h for IMRT and 483 hours for VMAT. Using VMAT, compared to IMRT, the maximum dose of the boost PTV was reduced by 0.4 Gy (P=.074), the mean dose in the anal sphincter by 1.6 Gy (P=.055), the conformity index of the 95% isodose (CI 95% ) by 0.02 (P=.005), and the rectal wall V 65 Gy by 1.1% (P=.008). Conclusions: We showed the feasibility of automatically generating Pareto fronts with Pinnacle 3 . Pareto fronts provide a valuable tool for performing objective comparative treatment planning studies. We compared VMAT with IMRT in prostate patients and found VMAT had a dosimetric advantage over IMRT
Inter-temporal variation in the travel time and travel cost parameters of transport models
Börjesson, Maria
2012-01-01
The parameters for travel time and travel cost are central in travel demand forecasting models. Since valuation of infrastructure investments requires prediction of travel demand for future evaluation years, inter-temporal variation of the travel time and travel cost parameters is a key issue in forecasting. Using two identical stated choice experiments conducted among Swedish drivers with an interval of 13 years, 1994 and 2007, this paper estimates the inter-temporal variation in travel time...
Precursor of transition to turbulence: spatiotemporal wave front.
Bhaumik, S; Sengupta, T K
2014-04-01
To understand transition to turbulence via 3D disturbance growth, we report here results obtained from the solution of Navier-Stokes equation (NSE) to reproduce experimental results obtained by minimizing background disturbances and imposing deterministic excitation inside the shear layer. A similar approach was adopted in Sengupta and Bhaumik [Phys. Rev. Lett. 107, 154501 (2011)], where a route of transition from receptivity to fully developed turbulent stage was explained for 2D flow in terms of the spatio-temporal wave-front (STWF). The STWF was identified as the unit process of 2D turbulence creation for low amplitude wall excitation. Theoretical prediction of STWF for boundary layer was established earlier in Sengupta, Rao, and Venkatasubbaiah [Phys. Rev. Lett. 96, 224504 (2006)] from the Orr-Sommerfeld equation as due to spatiotemporal instability. Here, the same unit process of the STWF during transition is shown to be present for 3D disturbance field from the solution of governing NSE.
Stress intensity factors and weight functions for cracks in front of notches
International Nuclear Information System (INIS)
Fett, T.
1993-12-01
The knowledge of stress intensity factors for cracks at notch roots is important for the fracture mechanical treatment of real components. Stress intensity factor solutions are available only for special notches and externally applied loads. For the treatment of more complex loadings as thermal stresses near the notch root the weight function is needed in addition. In the first part of this report weight functions for cracks in front of internal notches are derived from stress intensity factor solutions under external loading available in the literature. The second part deals with cracks in front of edge notches. Limit cases of stress intensity factors are derived which allow to estimate stress intensity factors for cracks in front of internal elliptical notches with arbitrary aspect ratio of the ellipse and for external notches. (orig.) [de
International Nuclear Information System (INIS)
Wendroff, B.
1992-01-01
An analysis of the equations of chromatography from the point of view of hyperbolic conservation laws has been reviewed in recent literature. Serre was able to prove that the Lax-Friedrichs difference scheme, Godunov's method, and the viscosity method, have a subsequence converging to a weak solution of the chromatography equations, with no restriction on the size of the initial data. The purpose of this note is to announce that two versions of front tracking can be added to this list. After a brief description of the properties of the chromatography system and a definition of front tracking we give the basic steps of the proof. An example showing the quality of a front tracking solution is given. The equations of idealized electrophoresis and multiphase incompressible flow are very similar to the chromatography equations, but the former have linearly degenerate characteristic field, creating contact discontinuities. In the final section we briefly indicate how our result for chromatography carries over to this case
The effect of a stationary precipitation front on nuclide dissolution and transport
International Nuclear Information System (INIS)
Light, W.B.; Chambre, P.L.; Lee, W.W.L.; Pigford, T.H.
1988-01-01
Waste material in a geologic repository will dissolve and migrate away. For many waste components, this process will be limited by the solubility of the waste matrix and species involved. In this paper the authors deal with a single contaminant species and analyze the effect of a precipitation front caused by a discontinuity in the solubility of the contaminant at some distance from the waste package. The precipitation front may be due to local geochemical changes such as changes in temperature, pH or redox potential, caused by nearby geologic features or the waste itself. The authors provide analytic solutions to the problem of precipitation at a stationary front. Numerical illustrations of these solutions are also presented
DEFF Research Database (Denmark)
Knudsen, Mette Aagaard
2014-01-01
, this is problematic. The average travel distance has steadily increased during the latest decades together with the increasing motorisation of daily travel and international aviation. Previously most focus has been on domestic daily travel activities, but globalisation has, together with changes in price structures......), the TU overnight survey, and the Danish Tourism Statistics from the Business and Holiday Survey (HBS). This has enabled focus on infrequent travel activities segmented relative to travel purpose, distance threshold, or travelling with overnight stays. At an overall level the thesis has three main.......g. socio-economic variables. The analysis of Danish travel activities described in the three different travel surveys has outlined detailed information on Danish travel behaviour at an aggregated level during the past two decades. It has above all revealed the significant role of leisure travel. Private...
Light-Front Holography and the Light-Front Schrodinger Equation
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J.; de Teramond, Guy
2012-08-15
One of the most important nonperturbative methods for solving QCD is quantization at fixed light-front time {tau} = t+z=c - Dirac's 'Front Form'. The eigenvalues of the light-front QCD Hamiltonian predict the hadron spectrum and the eigensolutions provide the light-front wavefunctions which describe hadron structure. More generally, we show that the valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a single-variable relativistic equation of motion, analogous to the nonrelativistic radial Schrodinger equation, with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. We outline a method for computing the required potential from first principles in QCD. The holographic mapping of gravity in AdS space to QCD, quantized at fixed light-front time, yields the same light front Schrodinger equation; in fact, the soft-wall AdS/QCD approach provides a model for the light-front potential which is color-confining and reproduces well the light-hadron spectrum. One also derives via light-front holography a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. The elastic and transition form factors of the pion and the nucleons are found to be well described in this framework. The light-front AdS/QCD holographic approach thus gives a frame-independent first approximation of the color-confining dynamics, spectroscopy, and excitation spectra of relativistic light-quark bound states in QCD.
A note on poroacoustic traveling waves under Forchheimer's law
International Nuclear Information System (INIS)
Jordan, P.M.
2013-01-01
Acoustic traveling waves in a gas that saturates a rigid porous medium is investigated under the assumption that the drag experienced by the gas is modeled by Forchheimer's law. Exact traveling wave solutions (TWS)s, as well as approximate and asymptotic expressions, are obtained; decay rates are determined; and acceleration wave results are presented. In addition, special cases are considered, critical values of the wave variable and parameters are derived, and comparisons with predictions based on Darcy's law are performed. It is shown that, with respect to the Darcy case, most of the metrics that characterize such waveforms exhibit an increase in magnitude under Forchheimer's law
A NEW HEURISTIC ALGORITHM FOR MULTIPLE TRAVELING SALESMAN PROBLEM
Directory of Open Access Journals (Sweden)
F. NURIYEVA
2017-06-01
Full Text Available The Multiple Traveling Salesman Problem (mTSP is a combinatorial optimization problem in NP-hard class. The mTSP aims to acquire the minimum cost for traveling a given set of cities by assigning each of them to a different salesman in order to create m number of tours. This paper presents a new heuristic algorithm based on the shortest path algorithm to find a solution for the mTSP. The proposed method has been programmed in C language and its performance analysis has been carried out on the library instances. The computational results show the efficiency of this method.
Morbidity among Israeli paediatric travellers.
Rabinowicz, Shira; Schwartz, Eli
2017-09-01
International travel, particularly to developing countries, is becoming increasingly common among the Israeli population, including an increase in the number of travelling children. Since children are a distinct travellers' population, data about their post-travel morbidity are needed. A retrospective study which examined all children (0-19 years old) who presented to our centre after international travel from 1999 to 2015. About 314 children were seen. The mean age was 10 years (SD ± 5.8). Most of the patients (80.6%) were tourists, and the rest were expatriates. The main destinations visited were South-Asia (46.5%), Sub-Saharan Africa (33.4%), Latin-America (7%) and Europe (6.4%). Overall, the most common diagnoses were gastrointestinal (GI) (mainly chronic) disorders (30.6%), followed by febrile diseases (26.4%), among which 18.1% of patients were diagnosed with dengue fever and 12% with malaria. Dermatologic conditions accounted for 25.2%. Additional diagnoses were schistosomiasis (6.4%) and neuropsychiatric symptoms (2.2%). A substantial part, 10.8%, had eosinophilia, either symptomatic or asymptomatic. Travellers to Asia, compared to travellers to Africa, presented more commonly with GI illness (OR 2.02, 95% confidence interval 1.13-3.61), and dermatologic conditions (OR 1.94, 95% confidence interval 1.05-3.61). Morbidity was associated with a variety of transmission modes, such as food-borne illnesses (30.9%), bite and sting wounds (10.2%), mosquito-borne infections (8%), freshwater contact (6.7%) and tick-borne infections (2.2%). The main conditions seen in paediatric returning travellers were GI, febrile and dermatologic illnesses, some may be rare in their country of origin. Targeting care for the suspected pathogens based on updated knowledge of epidemiology and thorough travel history is essential. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com
Knudsen, Mette Aagaard; Rich, Jeppe; Nielsen, Otto Anker
2014-01-01
Historically there has been a lack of knowledge with respect to long distance travel. Due to the considerable contribution of long distance travel to total travelled kilometres and the related energy consumption from the transport sector and derived impacts on greenhouse emissions, this is problematic. The average travel distance has steadily increased during the latest decades together with the increasing motorisation of daily travel and international aviation. Previously most focus has been...
Propagating gene expression fronts in a one-dimensional coupled system of artificial cells
Tayar, Alexandra M.; Karzbrun, Eyal; Noireaux, Vincent; Bar-Ziv, Roy H.
2015-12-01
Living systems employ front propagation and spatiotemporal patterns encoded in biochemical reactions for communication, self-organization and computation. Emulating such dynamics in minimal systems is important for understanding physical principles in living cells and in vitro. Here, we report a one-dimensional array of DNA compartments in a silicon chip as a coupled system of artificial cells, offering the means to implement reaction-diffusion dynamics by integrated genetic circuits and chip geometry. Using a bistable circuit we programmed a front of protein synthesis propagating in the array as a cascade of signal amplification and short-range diffusion. The front velocity is maximal at a saddle-node bifurcation from a bistable regime with travelling fronts to a monostable regime that is spatially homogeneous. Near the bifurcation the system exhibits large variability between compartments, providing a possible mechanism for population diversity. This demonstrates that on-chip integrated gene circuits are dynamical systems driving spatiotemporal patterns, cellular variability and symmetry breaking.
Does laser-driven heat front propagation depend on material microstructure?
Colvin, J. D.; Matsukuma, H.; Fournier, K. B.; Yoga, A.; Kemp, G. E.; Tanaka, N.; Zhang, Z.; Kota, K.; Tosaki, S.; Ikenouchi, T.; Nishimura, H.
2016-10-01
We showed earlier that the laser-driven heat front propagation velocity in low-density Ti-silica aerogel and TiO2 foam targets was slower than that simulated with a 2D radiation-hydrodynamics code incorporating an atomic kinetics model in non-LTE and assuming initially homogeneous material. Some theoretical models suggest that the heat front is slowed over what it would be in a homogeneous medium by the microstructure of the foam. In order to test this hypothesis we designed and conducted a comparison experiment on the GEKKO laser to measure heat front propagation velocity in two targets, one an Ar/CO2 gas mixture and the other a TiO2 foam, that had identical initial densities and average ionization states. We found that the heat front traveled about ten times faster in the gas than in the foam. We present the details of the experiment design and a comparison of the data with the simulations. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract No. DE-AC52-07NA27344, and the joint research project of ILE Osaka U. (contract Nos. 2014A1-04 and 2015A1-02).
Light-Front Quantization of Gauge Theories
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J.
2003-03-25
Light-front wavefunctions provide a frame-independent representation of hadrons in terms of their physical quark and gluon degrees of freedom. The light-front Hamiltonian formalism provides new nonperturbative methods for obtaining the QCD spectrum and eigensolutions, including resolvant methods, variational techniques, and discretized light-front quantization. A new method for quantizing gauge theories in light-cone gauge using Dirac brackets to implement constraints is presented. In the case of the electroweak theory, this method of light-front quantization leads to a unitary and renormalizable theory of massive gauge particles, automatically incorporating the Lorentz and 't Hooft conditions as well as the Goldstone boson equivalence theorem. Spontaneous symmetry breaking is represented by the appearance of zero modes of the Higgs field leaving the light-front vacuum equal to the perturbative vacuum. I also discuss an ''event amplitude generator'' for automatically computing renormalized amplitudes in perturbation theory. The importance of final-state interactions for the interpretation of diffraction, shadowing, and single-spin asymmetries in inclusive reactions such as deep inelastic lepton-hadron scattering is emphasized.
Light-Front Quantization of Gauge Theories
Energy Technology Data Exchange (ETDEWEB)
Brodskey, Stanley
2002-12-01
Light-front wavefunctions provide a frame-independent representation of hadrons in terms of their physical quark and gluon degrees of freedom. The light-front Hamiltonian formalism provides new nonperturbative methods for obtaining the QCD spectrum and eigensolutions, including resolvant methods, variational techniques, and discretized light-front quantization. A new method for quantizing gauge theories in light-cone gauge using Dirac brackets to implement constraints is presented. In the case of the electroweak theory, this method of light-front quantization leads to a unitary and renormalizable theory of massive gauge particles, automatically incorporating the Lorentz and 't Hooft conditions as well as the Goldstone boson equivalence theorem. Spontaneous symmetry breaking is represented by the appearance of zero modes of the Higgs field leaving the light-front vacuum equal to the perturbative vacuum. I also discuss an ''event amplitude generator'' for automatically computing renormalized amplitudes in perturbation theory. The importance of final-state interactions for the interpretation of diffraction, shadowing, and single-spin asymmetries in inclusive reactions such as deep inelastic lepton-hadron scattering is emphasized.
Statistical Physics and Light-Front Quantization
Energy Technology Data Exchange (ETDEWEB)
Raufeisen, J
2004-08-12
Light-front quantization has important advantages for describing relativistic statistical systems, particularly systems for which boost invariance is essential, such as the fireball created in a heavy ion collisions. In this paper the authors develop light-front field theory at finite temperature and density with special attention to quantum chromodynamics. They construct the most general form of the statistical operator allowed by the Poincare algebra and show that there are no zero-mode related problems when describing phase transitions. They then demonstrate a direct connection between densities in light-front thermal field theory and the parton distributions measured in hard scattering experiments. The approach thus generalizes the concept of a parton distribution to finite temperature. In light-front quantization, the gauge-invariant Green's functions of a quark in a medium can be defined in terms of just 2-component spinors and have a much simpler spinor structure than the equal-time fermion propagator. From the Green's function, the authors introduce the new concept of a light-front density matrix, whose matrix elements are related to forward and to off-diagonal parton distributions. Furthermore, they explain how thermodynamic quantities can be calculated in discretized light-cone quantization, which is applicable at high chemical potential and is not plagued by the fermion-doubling problems.
Sharp fronts within geochemical transport problems
International Nuclear Information System (INIS)
Grindrod, P.
1995-01-01
The authors consider some reactive geochemical transport problems in groundwater systems. When incoming fluid is in disequilibrium with the mineralogy sharp transition fronts may develop. They show that this is a generic property for a class of systems where the timescales associated with reaction and diffusion phenomena are much shorter than those associated with advective transport. Such multiple timescale problems are relevant to a variety of processes in natural systems: mathematically methods of singular perturbation theory reduce the dimension of the problems to be solved locally. Furthermore, they consider how spatial heterogeneous mineralogy can impact upon the propagation of sharp geochemical fronts. The authors developed an asymptotic approach in which they solve equations for the evolving geometry of the front and indicate how the non-smooth perturbations due to natural heterogeneity of the mineralogy on underlying ground water flow field are balanced against the smoothing effect of diffusion/dispersive processes. Fronts are curvature damped, and the results here indicate the generic nature of separate front propagation within both model (idealized) and natural (heterogeneous) geochemical systems
Towards More Responsible Business Travel : Green Travel Guide for Business Travellers
Aila, Anu
2010-01-01
The purpose of this research type thesis is to find ways how to develop sustainability in business travel. The target is increase the level of understanding and knowledge to respect natural environment and local cultures and find the right channels and ways to raise the knowledge. The study has been done to raise the awareness how business travel can be more sustainable. This thesis analyzes sustainable tourism based on the economic, environmental, and socio-cultural considerations. Green...
8 CFR 1244.15 - Travel abroad.
2010-01-01
... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Travel abroad. 1244.15 Section 1244.15... REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.15 Travel abroad. (a) After... Status shall not constitute permission to travel abroad. Permission to travel may be granted by the...
49 CFR 230.76 - Piston travel.
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 230.76 Section 230.76... Tenders Brake and Signal Equipment § 230.76 Piston travel. (a) Minimum piston travel. The minimum piston travel shall be sufficient to provide proper brake shoe clearance when the brakes are released. (b...
2010-01-01
... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Travel abroad. 244.15 Section 244.15 Aliens... NATIONALS OF DESIGNATED STATES § 244.15 Travel abroad. (a) After the grant of Temporary Protected Status... to travel abroad. Permission to travel may be granted by the director pursuant to the Service's...
A relational approach to analysing leisure travel
Ettema, D.F.; Schwanen, T.
2012-01-01
Leisure travel makes up a very significant part of daily travel and therefore needs to be considered in any travel demand management or general land use and transportation policy. Yet, research into leisure mobility has tended to ignore important aspects of leisure travel, such as its joint
Systematic front distortion and presence of consecutive fronts in a precipitation system
Volford, A.; Izsak, F.; Ripszam, M.; Lagzi, I.
2006-01-01
A new simple reaction-diffusion system is presented focusing on pattern formation phenomena as consecutive precipitation fronts and distortion of the precipitation front.The chemical system investigated here is based on the amphoteric property of aluminum hydroxide and exhibits two unique phenomena.
Employment of a metal microgrid as a front electrode in a sandwich-structured photodetector.
Zhang, Junying; Cai, Chao; Pan, Feng; Hao, Weichang; Zhang, Weiwei; Wang, Tianmin
2009-07-01
A highly UV-transparent metal microgrid was prepared and employed as the front electrode in a sandwich-structured ultraviolet (UV) photodetector using TiO(2) thin film as the semiconductor layer. The photo-generated charger carriers travel a shorter distance before reaching the electrodes in comparison with a photodetector using large-spaced interdigitated metal electrodes (where distance between fingers is several to tens of micrometers) on the surface of the semiconductor film. This photodetector responds to UV light irradiation, and the photocurrent intensity increases linearly with the irradiation intensity below 0.2 mW/cm(2).
The value of travel time variance
DEFF Research Database (Denmark)
Fosgerau, Mogens; Engelson, Leonid
2011-01-01
This paper considers the value of travel time variability under scheduling preferences that are defined in terms of linearly time varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability...... that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can freely choose departure time and to travellers who use a scheduled service with fixed headway. Depending...... on parameters, travellers may be risk averse or risk seeking and the value of travel time may increase or decrease in the mean travel time....
Exploring the Positive Utility of Travel and Mode Choice
2017-08-01
Why do people travel? Underlying most travel behavior research is the derived-demand paradigm of travel analysis, which assumes that travel demand is derived from the demand for spatially separated activities, traveling is a means to an end (reaching...
Traveling waves in a diffusive predator-prey model with holling type-III functional response
International Nuclear Information System (INIS)
Li Wantong; Wu Shiliang
2008-01-01
We establish the existence of traveling wave solutions and small amplitude traveling wave train solutions for a reaction-diffusion system based on a predator-prey model with Holling type-III functional response. The analysis is in the three-dimensional phase space of the nonlinear ordinary differential equation system given by the diffusive predator-prey system in the traveling wave variable. The methods used to prove the results are the shooting argument, invariant manifold theory and the Hopf bifurcation theorem
Optical Module Front-End for a Neutrino Underwater Telescope PMT interface
Lo Presti, D; Caponetto, L
2007-01-01
A proposal for a new system to capture signals in the Optical Module (OM) of an Underwater Neutrino Telescope is described. It concentrates on the problem of power consumption in relation to precision. In particular, a solution for the interface between the photomultiplier (PMT) and the front-end electronics is presented.
Czech Academy of Sciences Publication Activity Database
Adamovič, Jiří; Mikuláš, Radek; Navrátil, Tomáš
2015-01-01
Roč. 59, Supplement 1 (2015), s. 123-149 ISSN 0372-8854 R&D Projects: GA AV ČR IAA300130806; GA ČR GA13-28040S Institutional support: RVO:67985831 Keywords : symmetrical cavities * solutional landforms * cavernous weathering * tafoni * sandstone * concretions * carbonate dissolution front Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.103, year: 2015
Optimal back-to-front airplane boarding
Bachmat, Eitan; Khachaturov, Vassilii; Kuperman, Ran
2013-06-01
The problem of finding an optimal back-to-front airplane boarding policy is explored, using a mathematical model that is related to the 1+1 polynuclear growth model with concave boundary conditions and to causal sets in gravity. We study all airplane configurations and boarding group sizes. Optimal boarding policies for various airplane configurations are presented. Detailed calculations are provided along with simulations that support the main conclusions of the theory. We show that the effectiveness of back-to-front policies undergoes a phase transition when passing from lightly congested airplanes to heavily congested airplanes. The phase transition also affects the nature of the optimal or near-optimal policies. Under what we consider to be realistic conditions, optimal back-to-front policies lead to a modest 8-12% improvement in boarding time over random (no policy) boarding, using two boarding groups. Having more than two groups is not effective.
Optimal back-to-front airplane boarding.
Bachmat, Eitan; Khachaturov, Vassilii; Kuperman, Ran
2013-06-01
The problem of finding an optimal back-to-front airplane boarding policy is explored, using a mathematical model that is related to the 1+1 polynuclear growth model with concave boundary conditions and to causal sets in gravity. We study all airplane configurations and boarding group sizes. Optimal boarding policies for various airplane configurations are presented. Detailed calculations are provided along with simulations that support the main conclusions of the theory. We show that the effectiveness of back-to-front policies undergoes a phase transition when passing from lightly congested airplanes to heavily congested airplanes. The phase transition also affects the nature of the optimal or near-optimal policies. Under what we consider to be realistic conditions, optimal back-to-front policies lead to a modest 8-12% improvement in boarding time over random (no policy) boarding, using two boarding groups. Having more than two groups is not effective.
Front propagation in a regular vortex lattice: Dependence on the vortex structure.
Beauvier, E; Bodea, S; Pocheau, A
2017-11-01
We investigate the dependence on the vortex structure of the propagation of fronts in stirred flows. For this, we consider a regular set of vortices whose structure is changed by varying both their boundary conditions and their aspect ratios. These configurations are investigated experimentally in autocatalytic solutions stirred by electroconvective flows and numerically from kinematic simulations based on the determination of the dominant Fourier mode of the vortex stream function in each of them. For free lateral boundary conditions, i.e., in an extended vortex lattice, it is found that both the flow structure and the front propagation negligibly depend on vortex aspect ratios. For rigid lateral boundary conditions, i.e., in a vortex chain, vortices involve a slight dependence on their aspect ratios which surprisingly yields a noticeable decrease of the enhancement of front velocity by flow advection. These different behaviors reveal a sensitivity of the mean front velocity on the flow subscales. It emphasizes the intrinsic multiscale nature of front propagation in stirred flows and the need to take into account not only the intensity of vortex flows but also their inner structure to determine front propagation at a large scale. Differences between experiments and simulations suggest the occurrence of secondary flows in vortex chains at large velocity and large aspect ratios.
Diversity comparison of Pareto front approximations in many-objective optimization.
Li, Miqing; Yang, Shengxiang; Liu, Xiaohui
2014-12-01
Diversity assessment of Pareto front approximations is an important issue in the stochastic multiobjective optimization community. Most of the diversity indicators in the literature were designed to work for any number of objectives of Pareto front approximations in principle, but in practice many of these indicators are infeasible or not workable when the number of objectives is large. In this paper, we propose a diversity comparison indicator (DCI) to assess the diversity of Pareto front approximations in many-objective optimization. DCI evaluates relative quality of different Pareto front approximations rather than provides an absolute measure of distribution for a single approximation. In DCI, all the concerned approximations are put into a grid environment so that there are some hyperboxes containing one or more solutions. The proposed indicator only considers the contribution of different approximations to nonempty hyperboxes. Therefore, the computational cost does not increase exponentially with the number of objectives. In fact, the implementation of DCI is of quadratic time complexity, which is fully independent of the number of divisions used in grid. Systematic experiments are conducted using three groups of artificial Pareto front approximations and seven groups of real Pareto front approximations with different numbers of objectives to verify the effectiveness of DCI. Moreover, a comparison with two diversity indicators used widely in many-objective optimization is made analytically and empirically. Finally, a parametric investigation reveals interesting insights of the division number in grid and also offers some suggested settings to the users with different preferences.
PIV tracer behavior on propagating shock fronts
International Nuclear Information System (INIS)
Glazyrin, Fyodor N; Mursenkova, Irina V; Znamenskaya, Irina A
2016-01-01
The present work was aimed at the quantitative particle image velocimetry (PIV) measurement of a velocity field near the front of a propagating shock wave and the study of the dynamics of liquid tracers crossing the shock front. For this goal, a shock tube with a rectangular cross-section (48 × 24 mm) was used. The flat shock wave with Mach numbers M = 1.4–2.0 propagating inside the tube channel was studied as well as an expanding shock wave propagating outside the channel with M = 1.2–1.8 at its main axis. The PIV imaging of the shock fronts was carried out with an aerosol of dioctyl sebacate (DEHS) as tracer particles. The pressures of the gas in front of the shock waves studied ranged from 0.013 Mpa to 0.1 MPa in the series of experiments. The processed PIV data, compared to the 1D normal shock theory, yielded consistent values of wake velocity immediately behind the plain shock wave. Special attention was paid to the blurring of the velocity jump on the shock front due to the inertial particle lag and peculiarities of the PIV technique. A numerical algorithm was developed for analysis and correction of the PIV data on the shock fronts, based on equations of particle-flow interaction. By application of this algorithm, the effective particle diameter of the DEHS aerosol tracers was estimated as 1.03 ± 0.12 μm. A number of different formulations for particle drag were tested with this algorithm, with varying success. The results show consistency with previously reported experimental data obtained for cases of stationary shock waves. (paper)
Guerrero-Lillo, Lisette; Medrano-Díaz, Jorge; Pérez, Carmen; Chacón, Rodrigo; Silva-Urra, Juan; Rodriguez-Morales, Alfonso J
2009-01-01
Because information about travel medicine in Chile is lacking, a knowledge, attitudes, and practices evaluation in international travelers and medical students was done. The travelers and medical students did not know the travel medicine and sanitary conditions of their destinations, although they perceived travel-associated health risks, but <10% had any vaccination and 5% got sick during international trips.
2011-07-20
...; Sequence 5] Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public... public meeting. SUMMARY: The General Services Administration (GSA) is revising the Federal Travel Regulation (FTR) in an effort to streamline travel policies, increase travel efficiency and effectiveness...
2011-08-02
...; Sequence 5] Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public... and the general public in an effort to streamline travel policies, incorporated travel efficiency and.... Flynn, Deputy Director, Office of Travel, Transportation & Asset Management. [FR Doc. 2011-19482 Filed 8...
Ettema, D.F.; Timmermans, H.J.P.
2006-01-01
A negative effect of congestion that tends to be overlooked is travel time uncertainty. Travel time uncertainty causes scheduling costs due to early or late arrival. The negative effects of travel time uncertainty can be reduced by providing travellers with travel time information, which improves
Observational Study of Travelers' Diarrhea.
Meuris
1995-03-01
Background: European air travelers returning from Algeria, Egypt, Mexico, Morocco, and Tunisia were interviewed about their experience of travelers' diseases upon arrival in Brussels. Diarrhea was mentioned by 37% of the adults and 27% of the children. These subjects were questioned about the types of measures taken, type and duration of drug treatment (if any), and about duration of diarrhea and side effects experienced. Methods: Final analysis was performed based on 2160 interviews. The largest proportion of diarrhea was reported in the age group 15-24 years (46%). Results: The majority of the 2160 subjects had opted for drug treatment (81%): 927 subjects for loperamide alone, 235 for loperamide in combination with nifuroxazide, and 178 for nifuroxazide alone. Other drugs had been used less frequently. The median time to recovery was 2.4 days with loperamide compared to 3.2 days with nifuroxazide and to 3.4 days for the no-treatment group. Conclusions: A stratification of the results by severity of the diarrhea suggests a rank of antidiarrheal potency as follows: loperamide > nifuroxazide > no-drug treatment. The side effect with the highest incidence was constipation (2.4% with loperamide). (J Travel Med 2:11-15, 1995) Travelers' diarrhea is usually defined as the passage of at least three unformed stools per day or any number of such stools when accompanied by fever, abdominal cramping, or vomiting. The definition may be broadened to include more trivial bowel disturbance.1,2 The duration of this self-limited disease generally is 3 to 5 days. Medical intervention aims at shortening the duration of disease, thus allowing the sufferer to resume his or her usual activities at an early stage. A shortened period of recovery to physical well-being has obvious favorable economic implications if the traveler is on business and may help the maintenance of a desired level of quality of life while a traveler is on holiday. An observational study of various medical
Exact solutions to the Lienard equation and its applications
International Nuclear Information System (INIS)
Feng Zhaosheng
2004-01-01
In this paper, a kind of explicit exact solutions to the Lienard equation is obtained, and the applications of the result in seeking traveling solitary wave solution of the nonlinear Schroedinger equation are presented
RF front-end world class designs
Love, Janine
2009-01-01
All the design and development inspiration and direction a harware engineer needs in one blockbuster book! Janine Love site editor for RF Design Line,columnist, and author has selected the very best RF design material from the Newnes portfolio and has compiled it into this volume. The result is a book covering the gamut of RF front end design from antenna and filter design fundamentals to optimized layout techniques with a strong pragmatic emphasis. In addition to specific design techniques and practices, this book also discusses various approaches to solving RF front end design problems and h
THREE PERSPECTIVES ON MANAGING FRONT END INNOVATION
DEFF Research Database (Denmark)
Jensen, Anna Rose Vagn; Clausen, Christian; Gish, Liv
2018-01-01
as a complementary perspective. The paper combines a literature review with an empirical examination of the application of these multiple perspectives across three cases of front end of innovation (FEI) management in mature product developing companies. While the process models represent the dominant, albeit rather...... to represent an emergent approach in managing FEI where process models, knowledge strategies and objects become integrated elements in more advanced navigational strategies for key players.......This paper presents three complementary perspectives on the management of front end innovation: A process model perspective, a knowledge perspective and a translational perspective. While the first two perspectives are well established in literature, we offer the translation perspective...
Light-front nuclear shell-model
International Nuclear Information System (INIS)
Johnson, M.B.
1990-01-01
I examine the effects of nuclear structure on high-energy, high-momentum transfer processes, specifically the EMC effect. For pedagogical reasons, a fictitious but simple two-body system consisting of two equal-mass particles interacting in a harmonic oscillator potential has been chosen. For this toy nucleus, I utilize a widely-used link between instant-form and light-front dynamics, formulating nuclear structure and deep-inelastic scattering consistently in the laboratory system. Binding effects are compared within conventional instant-form and light-front dynamical frameworks, with appreciable differences being found in the two cases. 20 refs
Extremal inversion of lunar travel time data. [seismic velocity structure
Burkhard, N.; Jackson, D. D.
1975-01-01
The tau method, developed by Bessonova et al. (1974), of inversion of travel times is applied to lunar P-wave travel time data to find limits on the velocity structure of the moon. Tau is the singular solution to the Clairaut equation. Models with low-velocity zones, with low-velocity zones at differing depths, and without low-velocity zones, were found to be consistent with data and within the determined limits. Models with and without a discontinuity at about 25-km depth have been found which agree with all travel time data to within two standard deviations. In other words, the existence of the discontinuity and its size and location have not been uniquely resolved. Models with low-velocity channels are also possible.
Health, sustainability and student travel.
Green, Gill; Morris, Jenny; Wade, Margaret
2012-01-01
A survey of 246 pre-registration nursing students in a University in the South West of England was carried out to explore the impact of course related travel on the student experience. Results from the survey indicated that students' main mode of transport to practice placements was by car which reflects the rural nature of the South West and the relative paucity of public transport. Long distances that many students travel to their study centre and to placements, and the concurrent financial strain that this creates, impacted negatively on the student experience. Students recognised the need to travel to a place of study and clinical placements and suggestions of minimising the negative impact of travel were offered. These included the increased use of electronic delivery of lectures, attendance at local university premises, the provision of shared transport to placements and placements closer to the student's home. Few students, however, considered the environmental impact of travel. Higher Education Institutions need to address issues of sustainability through promoting student wellbeing and taking steps to reduce greenhouse gas emissions. It is therefore important that student awareness of sustainability related issues is increased as well as focusing on reducing the environmental impact through organisational change. Copyright © 2011 Elsevier Ltd. All rights reserved.
Future Trends in Business Travel Decision Making
Mason, Keith J.
2002-01-01
This research surveys twenty large companies and their travellers to identify and evaluate the effects of pressures on the business travel market in the future. The influence of the following areas on the decision making process are addressed: (1) Corporate travel policies and increasing professionalism in corporate purchasing; (2) The development of global strategic airline alliances; (3) The emergence of low cost airlines on short haul markets; and (4) The development of internet based booking tools and travel agency IT. The survey shows differences in views between travel managers, and travellers with regard to corporate travel policies. While travel managers see policy rules, travellers interpret these as guidelines, indicating travel managers will need to take further actions to exercise true control of travel budgets. The data shows that companies are more likely to prescribe a class of airline ticket, than the choice of airline itself. Corporate hierarchical bias in travel policies is still common both for short and particularly long haul flying. Other findings show that while travel managers believe that their companies are likely to sign global deals with strategic airline groups within a five year period in a bid to consolidating spending, they also believe that nearly a third of short haul flying will be taken with low cost carriers, indicating further penetration in this business travel market by these carriers. The paper also provides other predictions about the business travel market, based on the survey findings.