Generation and monitoring of a discrete stable random process
Hopcraft, K I; Matthews, J O
2002-01-01
A discrete stochastic process with stationary power law distribution is obtained from a death-multiple immigration population model. Emigrations from the population form a random series of events which are monitored by a counting process with finite-dynamic range and response time. It is shown that the power law behaviour of the population is manifested in the intermittent behaviour of the series of events. (letter to the editor)
International Nuclear Information System (INIS)
Matthews, J O; Hopcraft, K I; Jakeman, E
2003-01-01
Some properties of classical population processes that comprise births, deaths and multiple immigrations are investigated. The rates at which the immigrants arrive can be tailored to produce a population whose steady state fluctuations are described by a pre-selected distribution. Attention is focused on the class of distributions with a discrete stable law, which have power-law tails and whose moments and autocorrelation function do not exist. The separate problem of monitoring and characterizing the fluctuations is studied, analysing the statistics of individuals that leave the population. The fluctuations in the size of the population are transferred to the times between emigrants that form an intermittent time series of events. The emigrants are counted with a detector of finite dynamic range and response time. This is modelled through clipping the time series or saturating it at an arbitrary but finite level, whereupon its moments and correlation properties become finite. Distributions for the time to the first counted event and for the time between events exhibit power-law regimes that are characteristic of the fluctuations in population size. The processes provide analytical models with which properties of complex discrete random phenomena can be explored, and in addition provide generic means by which random time series encompassing a wide range of intermittent and other discrete random behaviour may be generated
On the Fractional Poisson Process and the Discretized Stable Subordinator
Directory of Open Access Journals (Sweden)
Rudolf Gorenflo
2015-08-01
Full Text Available We consider the renewal counting number process N = N(t as a forward march over the non-negative integers with independent identically distributed waiting times. We embed the values of the counting numbers N in a “pseudo-spatial” non-negative half-line x ≥ 0 and observe that for physical time likewise we have t ≥ 0. Thus we apply the Laplace transform with respect to both variables x and t. Applying then a modification of the Montroll-Weiss-Cox formalism of continuous time random walk we obtain the essential characteristics of a renewal process in the transform domain and, if we are lucky, also in the physical domain. The process t = t(N of accumulation of waiting times is inverse to the counting number process, in honour of the Danish mathematician and telecommunication engineer A.K. Erlang we call it the Erlang process. It yields the probability of exactly n renewal events in the interval (0; t]. We apply our Laplace-Laplace formalism to the fractional Poisson process whose waiting times are of Mittag-Leffler type and to a renewal process whose waiting times are of Wright type. The process of Mittag-Leffler type includes as a limiting case the classical Poisson process, the process of Wright type represents the discretized stable subordinator and a re-scaled version of it was used in our method of parametric subordination of time-space fractional diffusion processes. Properly rescaling the counting number process N(t and the Erlang process t(N yields as diffusion limits the inverse stable and the stable subordinator, respectively.
An Efficient Approach for Identifying Stable Lobes with Discretization Method
Directory of Open Access Journals (Sweden)
Baohai Wu
2013-01-01
Full Text Available This paper presents a new approach for quick identification of chatter stability lobes with discretization method. Firstly, three different kinds of stability regions are defined: absolute stable region, valid region, and invalid region. Secondly, while identifying the chatter stability lobes, three different regions within the chatter stability lobes are identified with relatively large time intervals. Thirdly, stability boundary within the valid regions is finely calculated to get exact chatter stability lobes. The proposed method only needs to test a small portion of spindle speed and cutting depth set; about 89% computation time is savedcompared with full discretization method. It spends only about10 minutes to get exact chatter stability lobes. Since, based on discretization method, the proposed method can be used for different immersion cutting including low immersion cutting process, the proposed method can be directly implemented in the workshop to promote machining parameters selection efficiency.
Characterization of Stochastic Dominance for Discrete Random Variable
Courtault, Jean-Michel; Crettez, Bertrand; Hayek, Naïla
2006-01-01
Working paper; Available characterizations of the various notions of stochastic dominance concern continuous random variables. Yet, discrete random variables are often used either in pedagogical presentations of stochastic dominance or in experimental tests of this notion. This note provides complete characterizations of the various notions of stochastic dominance for discrete random variables.
On order statistics from nonidentical discrete random variables
Directory of Open Access Journals (Sweden)
Yüzbaşı Bahadır
2016-01-01
Full Text Available In this study, pf and df of single order statistic of nonidentical discrete random variables are obtained. These functions are also expressed in integral form. Finally, pf and df of extreme of order statistics of random variables for the nonidentical discrete case are given.
General discrete random walk with variable absorbing probabilities
van Uem, Theo
2009-01-01
We obtain expected number of arrivals, probability of arrival, absorption probabilities and expected time before absorption for a general discrete random walk with variable absorbing probabilities on a finite interval using Fibonacci numbers
International Nuclear Information System (INIS)
Kang, Li; Tang, Sanyi
2016-01-01
Highlights: • The discrete single species and multiple species models with random perturbation are proposed. • The complex dynamics and interesting bifurcation behavior have been investigated. • The reverse effects of random perturbation on discrete systems have been discussed and revealed. • The main results can be applied for pest control and resources management. - Abstract: The natural species are likely to present several interesting and complex phenomena under random perturbations, which have been confirmed by simple mathematical models. The important questions are: how the random perturbations influence the dynamics of the discrete population models with multiple steady states or multiple species interactions? and is there any different effects for single species and multiple species models with random perturbation? To address those interesting questions, we have proposed the discrete single species model with two stable equilibria and the host-parasitoid model with Holling type functional response functions to address how the random perturbation affects the dynamics. The main results indicate that the random perturbation does not change the number of blurred orbits of the single species model with two stable steady states compared with results for the classical Ricker model with same random perturbation, but it can strength the stability. However, extensive numerical investigations depict that the random perturbation does not influence the complexities of the host-parasitoid models compared with the results for the models without perturbation, while it does increase the period of periodic orbits doubly. All those confirm that the random perturbation has a reverse effect on the dynamics of the discrete single and multiple population models, which could be applied in reality including pest control and resources management.
A discrete random walk on the hypercube
Zhang, Jingyuan; Xiang, Yonghong; Sun, Weigang
2018-03-01
In this paper, we study the scaling for mean first-passage time (MFPT) of random walks on the hypercube and obtain a closed-form formula for the MFPT over all node pairs. We also determine the exponent of scaling efficiency characterizing the random walks and compare it with those of the existing networks. Finally we study the random walks on the hypercube with a located trap and provide a solution of the Kirchhoff index of the hypercube.
Discrete random signal processing and filtering primer with Matlab
Poularikas, Alexander D
2013-01-01
Engineers in all fields will appreciate a practical guide that combines several new effective MATLAB® problem-solving approaches and the very latest in discrete random signal processing and filtering.Numerous Useful Examples, Problems, and Solutions - An Extensive and Powerful ReviewWritten for practicing engineers seeking to strengthen their practical grasp of random signal processing, Discrete Random Signal Processing and Filtering Primer with MATLAB provides the opportunity to doubly enhance their skills. The author, a leading expert in the field of electrical and computer engineering, offe
Random discrete Morse theory and a new library of triangulations
DEFF Research Database (Denmark)
Benedetti, Bruno; Lutz, Frank Hagen
2014-01-01
We introduce random discrete Morse theory as a computational scheme to measure the complexity of a triangulation. The idea is to try to quantify the frequency of discrete Morse matchings with few critical cells. Our measure will depend on the topology of the space, but also on how nicely the space...... is triangulated. The scheme we propose looks for optimal discrete Morse functions with an elementary random heuristic. Despite its naiveté, this approach turns out to be very successful even in the case of huge inputs. In our view, the existing libraries of examples in computational topology are “too easy......” for testing algorithms based on discrete Morse theory. We propose a new library containing more complicated (and thus more meaningful) test examples....
Mishchenko, Michael I.; Dlugach, Janna M.; Yurkin, Maxim A.; Bi, Lei; Cairns, Brian; Liu, Li; Panetta, R. Lee; Travis, Larry D.; Yang, Ping; Zakharova, Nadezhda T.
2016-01-01
A discrete random medium is an object in the form of a finite volume of a vacuum or a homogeneous material medium filled with quasi-randomly and quasi-uniformly distributed discrete macroscopic impurities called small particles. Such objects are ubiquitous in natural and artificial environments. They are often characterized by analyzing theoretically the results of laboratory, in situ, or remote-sensing measurements of the scattering of light and other electromagnetic radiation. Electromagnetic scattering and absorption by particles can also affect the energy budget of a discrete random medium and hence various ambient physical and chemical processes. In either case electromagnetic scattering must be modeled in terms of appropriate optical observables, i.e., quadratic or bilinear forms in the field that quantify the reading of a relevant optical instrument or the electromagnetic energy budget. It is generally believed that time-harmonic Maxwell's equations can accurately describe elastic electromagnetic scattering by macroscopic particulate media that change in time much more slowly than the incident electromagnetic field. However, direct solutions of these equations for discrete random media had been impracticable until quite recently. This has led to a widespread use of various phenomenological approaches in situations when their very applicability can be questioned. Recently, however, a new branch of physical optics has emerged wherein electromagnetic scattering by discrete and discretely heterogeneous random media is modeled directly by using analytical or numerically exact computer solutions of the Maxwell equations. Therefore, the main objective of this Report is to formulate the general theoretical framework of electromagnetic scattering by discrete random media rooted in the Maxwell- Lorentz electromagnetics and discuss its immediate analytical and numerical consequences. Starting from the microscopic Maxwell-Lorentz equations, we trace the development of
International Nuclear Information System (INIS)
Mishchenko, Michael I.; Dlugach, Janna M.; Yurkin, Maxim A.; Bi, Lei; Cairns, Brian; Liu, Li; Panetta, R. Lee; Travis, Larry D.; Yang, Ping; Zakharova, Nadezhda T.
2016-01-01
A discrete random medium is an object in the form of a finite volume of a vacuum or a homogeneous material medium filled with quasi-randomly and quasi-uniformly distributed discrete macroscopic impurities called small particles. Such objects are ubiquitous in natural and artificial environments. They are often characterized by analyzing theoretically the results of laboratory, in situ, or remote-sensing measurements of the scattering of light and other electromagnetic radiation. Electromagnetic scattering and absorption by particles can also affect the energy budget of a discrete random medium and hence various ambient physical and chemical processes. In either case electromagnetic scattering must be modeled in terms of appropriate optical observables, i.e., quadratic or bilinear forms in the field that quantify the reading of a relevant optical instrument or the electromagnetic energy budget. It is generally believed that time-harmonic Maxwell’s equations can accurately describe elastic electromagnetic scattering by macroscopic particulate media that change in time much more slowly than the incident electromagnetic field. However, direct solutions of these equations for discrete random media had been impracticable until quite recently. This has led to a widespread use of various phenomenological approaches in situations when their very applicability can be questioned. Recently, however, a new branch of physical optics has emerged wherein electromagnetic scattering by discrete and discretely heterogeneous random media is modeled directly by using analytical or numerically exact computer solutions of the Maxwell equations. Therefore, the main objective of this Report is to formulate the general theoretical framework of electromagnetic scattering by discrete random media rooted in the Maxwell–Lorentz electromagnetics and discuss its immediate analytical and numerical consequences. Starting from the microscopic Maxwell–Lorentz equations, we trace the development
Mishchenko, Michael I.; Dlugach, Janna M.; Yurkin, Maxim A.; Bi, Lei; Cairns, Brian; Liu, Li; Panetta, R. Lee; Travis, Larry D.; Yang, Ping; Zakharova, Nadezhda T.
2018-01-01
A discrete random medium is an object in the form of a finite volume of a vacuum or a homogeneous material medium filled with quasi-randomly and quasi-uniformly distributed discrete macroscopic impurities called small particles. Such objects are ubiquitous in natural and artificial environments. They are often characterized by analyzing theoretically the results of laboratory, in situ, or remote-sensing measurements of the scattering of light and other electromagnetic radiation. Electromagnetic scattering and absorption by particles can also affect the energy budget of a discrete random medium and hence various ambient physical and chemical processes. In either case electromagnetic scattering must be modeled in terms of appropriate optical observables, i.e., quadratic or bilinear forms in the field that quantify the reading of a relevant optical instrument or the electromagnetic energy budget. It is generally believed that time-harmonic Maxwell’s equations can accurately describe elastic electromagnetic scattering by macroscopic particulate media that change in time much more slowly than the incident electromagnetic field. However, direct solutions of these equations for discrete random media had been impracticable until quite recently. This has led to a widespread use of various phenomenological approaches in situations when their very applicability can be questioned. Recently, however, a new branch of physical optics has emerged wherein electromagnetic scattering by discrete and discretely heterogeneous random media is modeled directly by using analytical or numerically exact computer solutions of the Maxwell equations. Therefore, the main objective of this Report is to formulate the general theoretical framework of electromagnetic scattering by discrete random media rooted in the Maxwell–Lorentz electromagnetics and discuss its immediate analytical and numerical consequences. Starting from the microscopic Maxwell–Lorentz equations, we trace the development
Entropy-stable summation-by-parts discretization of the Euler equations on general curved elements
Crean, Jared; Hicken, Jason E.; Del Rey Fernández, David C.; Zingg, David W.; Carpenter, Mark H.
2018-03-01
We present and analyze an entropy-stable semi-discretization of the Euler equations based on high-order summation-by-parts (SBP) operators. In particular, we consider general multidimensional SBP elements, building on and generalizing previous work with tensor-product discretizations. In the absence of dissipation, we prove that the semi-discrete scheme conserves entropy; significantly, this proof of nonlinear L2 stability does not rely on integral exactness. Furthermore, interior penalties can be incorporated into the discretization to ensure that the total (mathematical) entropy decreases monotonically, producing an entropy-stable scheme. SBP discretizations with curved elements remain accurate, conservative, and entropy stable provided the mapping Jacobian satisfies the discrete metric invariants; polynomial mappings at most one degree higher than the SBP operators automatically satisfy the metric invariants in two dimensions. In three-dimensions, we describe an elementwise optimization that leads to suitable Jacobians in the case of polynomial mappings. The properties of the semi-discrete scheme are verified and investigated using numerical experiments.
Inferring Team Strengths Using a Discrete Markov Random Field
Zech, John; Wood, Frank
2013-01-01
We propose an original model for inferring team strengths using a Markov Random Field, which can be used to generate historical estimates of the offensive and defensive strengths of a team over time. This model was designed to be applied to sports such as soccer or hockey, in which contest outcomes take value in a limited discrete space. We perform inference using a combination of Expectation Maximization and Loopy Belief Propagation. The challenges of working with a non-convex optimization p...
Discrete-Time Stable Generalized Self-Learning Optimal Control With Approximation Errors.
Wei, Qinglai; Li, Benkai; Song, Ruizhuo
2018-04-01
In this paper, a generalized policy iteration (GPI) algorithm with approximation errors is developed for solving infinite horizon optimal control problems for nonlinear systems. The developed stable GPI algorithm provides a general structure of discrete-time iterative adaptive dynamic programming algorithms, by which most of the discrete-time reinforcement learning algorithms can be described using the GPI structure. It is for the first time that approximation errors are explicitly considered in the GPI algorithm. The properties of the stable GPI algorithm with approximation errors are analyzed. The admissibility of the approximate iterative control law can be guaranteed if the approximation errors satisfy the admissibility criteria. The convergence of the developed algorithm is established, which shows that the iterative value function is convergent to a finite neighborhood of the optimal performance index function, if the approximate errors satisfy the convergence criterion. Finally, numerical examples and comparisons are presented.
Barth, Timothy; Charrier, Pierre; Mansour, Nagi N. (Technical Monitor)
2001-01-01
We consider the discontinuous Galerkin (DG) finite element discretization of first order systems of conservation laws derivable as moments of the kinetic Boltzmann equation. This includes well known conservation law systems such as the Euler For the class of first order nonlinear conservation laws equipped with an entropy extension, an energy analysis of the DG method for the Cauchy initial value problem is developed. Using this DG energy analysis, several new variants of existing numerical flux functions are derived and shown to be energy stable.
Migliorati, G.
2013-05-30
In this work we consider the random discrete L^2 projection on polynomial spaces (hereafter RDP) for the approximation of scalar quantities of interest (QOIs) related to the solution of a partial differential equation model with random input parameters. In the RDP technique the QOI is first computed for independent samples of the random input parameters, as in a standard Monte Carlo approach, and then the QOI is approximated by a multivariate polynomial function of the input parameters using a discrete least squares approach. We consider several examples including the Darcy equations with random permeability, the linear elasticity equations with random elastic coefficient, and the Navier--Stokes equations in random geometries and with random fluid viscosity. We show that the RDP technique is well suited to QOIs that depend smoothly on a moderate number of random parameters. Our numerical tests confirm the theoretical findings in [G. Migliorati, F. Nobile, E. von Schwerin, and R. Tempone, Analysis of the Discrete $L^2$ Projection on Polynomial Spaces with Random Evaluations, MOX report 46-2011, Politecnico di Milano, Milano, Italy, submitted], which have shown that, in the case of a single uniformly distributed random parameter, the RDP technique is stable and optimally convergent if the number of sampling points is proportional to the square of the dimension of the polynomial space. Here optimality means that the weighted $L^2$ norm of the RDP error is bounded from above by the best $L^\\\\infty$ error achievable in the given polynomial space, up to logarithmic factors. In the case of several random input parameters, the numerical evidence indicates that the condition on quadratic growth of the number of sampling points could be relaxed to a linear growth and still achieve stable and optimal convergence. This makes the RDP technique very promising for moderately high dimensional uncertainty quantification.
Nobile, Fabio
2015-01-07
We consider a general problem F(u, y) = 0 where u is the unknown solution, possibly Hilbert space valued, and y a set of uncertain parameters. We specifically address the situation in which the parameterto-solution map u(y) is smooth, however y could be very high (or even infinite) dimensional. In particular, we are interested in cases in which F is a differential operator, u a Hilbert space valued function and y a distributed, space and/or time varying, random field. We aim at reconstructing the parameter-to-solution map u(y) from random noise-free or noisy observations in random points by discrete least squares on polynomial spaces. The noise-free case is relevant whenever the technique is used to construct metamodels, based on polynomial expansions, for the output of computer experiments. In the case of PDEs with random parameters, the metamodel is then used to approximate statistics of the output quantity. We discuss the stability of discrete least squares on random points show convergence estimates both in expectation and probability. We also present possible strategies to select, either a-priori or by adaptive algorithms, sequences of approximating polynomial spaces that allow to reduce, and in some cases break, the curse of dimensionality
Exponential H∞ filtering for discrete-time switched neural networks with random delays.
Mathiyalagan, Kalidass; Su, Hongye; Shi, Peng; Sakthivel, Rathinasamy
2015-04-01
This paper addresses the exponential H∞ filtering problem for a class of discrete-time switched neural networks with random time-varying delays. The involved delays are assumed to be randomly time-varying which are characterized by introducing a Bernoulli stochastic variable. Effects of both variation range and distribution probability of the time delays are considered. The nonlinear activation functions are assumed to satisfy the sector conditions. Our aim is to estimate the state by designing a full order filter such that the filter error system is globally exponentially stable with an expected decay rate and a H∞ performance attenuation level. The filter is designed by using a piecewise Lyapunov-Krasovskii functional together with linear matrix inequality (LMI) approach and average dwell time method. First, a set of sufficient LMI conditions are established to guarantee the exponential mean-square stability of the augmented system and then the parameters of full-order filter are expressed in terms of solutions to a set of LMI conditions. The proposed LMI conditions can be easily solved by using standard software packages. Finally, numerical examples by means of practical problems are provided to illustrate the effectiveness of the proposed filter design.
On the joint statistics of stable random processes
International Nuclear Information System (INIS)
Hopcraft, K I; Jakeman, E
2011-01-01
A utilitarian continuous bi-variate random process whose first-order probability density function is a stable random variable is constructed. Results paralleling some of those familiar from the theory of Gaussian noise are derived. In addition to the joint-probability density for the process, these include fractional moments and structure functions. Although the correlation functions for stable processes other than Gaussian do not exist, we show that there is coherence between values adopted by the process at different times, which identifies a characteristic evolution with time. The distribution of the derivative of the process, and the joint-density function of the value of the process and its derivative measured at the same time are evaluated. These enable properties to be calculated analytically such as level crossing statistics and those related to the random telegraph wave. When the stable process is fractal, the proportion of time it spends at zero is finite and some properties of this quantity are evaluated, an optical interpretation for which is provided. (paper)
An approximate method for Bayesian entropy estimation for a discrete random variable.
Yokota, Yasunari
2004-01-01
This article proposes an approximated Bayesian entropy estimator for a discrete random variable. An entropy estimator that achieves least square error is obtained through Bayesian estimation of the occurrence probabilities of each value taken by the discrete random variable. This Bayesian entropy estimator requires large amount of calculation cost if the random variable takes numerous sorts of values. Therefore, the present article proposes a practical method for calculating an Bayesian entropy estimate; the proposed method utilizes approximation of the entropy function by a truncated Taylor series. Numerical experiments demonstrate that the proposed entropy estimation method improves estimation precision of entropy remarkably in comparison to the conventional entropy estimation method.
Directory of Open Access Journals (Sweden)
Hideki Katagiri
2017-10-01
Full Text Available This paper considers linear programming problems (LPPs where the objective functions involve discrete fuzzy random variables (fuzzy set-valued discrete random variables. New decision making models, which are useful in fuzzy stochastic environments, are proposed based on both possibility theory and probability theory. In multi-objective cases, Pareto optimal solutions of the proposed models are newly defined. Computational algorithms for obtaining the Pareto optimal solutions of the proposed models are provided. It is shown that problems involving discrete fuzzy random variables can be transformed into deterministic nonlinear mathematical programming problems which can be solved through a conventional mathematical programming solver under practically reasonable assumptions. A numerical example of agriculture production problems is given to demonstrate the applicability of the proposed models to real-world problems in fuzzy stochastic environments.
Globally asymptotically stable analysis in a discrete time eco-epidemiological system
International Nuclear Information System (INIS)
Hu, Zengyun; Teng, Zhidong; Zhang, Tailei; Zhou, Qiming; Chen, Xi
2017-01-01
Highlights: • Dynamical behaviors of a discrete time eco-epidemiological system are discussed. • Global asymptotical stability of this system is obtained by an iteration scheme which can be expended to general dimensional discrete system. • More complex dynamical behaviors are obtained by numerical simulations. - Abstract: In this study, the dynamical behaviors of a discrete time eco-epidemiological system are discussed. The local stability, bifurcation and chaos are obtained. Moreover, the global asymptotical stability of this system is explored by an iteration scheme. The numerical simulations illustrate the theoretical results and exhibit the complex dynamical behaviors such as flip bifurcation, Hopf bifurcation and chaotic dynamical behaviors. Our main results provide an efficient method to analyze the global asymptotical stability for general three dimensional discrete systems.
Generation of Random Particle Packings for Discrete Element Models
Abe, S.; Weatherley, D.; Ayton, T.
2012-04-01
An important step in the setup process of Discrete Element Model (DEM) simulations is the generation of a suitable particle packing. There are quite a number of properties such a granular material specimen should ideally have, such as high coordination number, isotropy, the ability to fill arbitrary bounding volumes and the absence of locked-in stresses. An algorithm which is able to produce specimens fulfilling these requirements is the insertion based sphere packing algorithm originally proposed by Place and Mora, 2001 [2] and extended in this work. The algorithm works in two stages. First a number of "seed" spheres are inserted into the bounding volume. In the second stage the gaps between the "seed" spheres are filled by inserting new spheres in a way so they have D+1 (i.e. 3 in 2D, 4 in 3D) touching contacts with either other spheres or the boundaries of the enclosing volume. Here we present an implementation of the algorithm and a systematic statistical analysis of the generated sphere packings. The analysis of the particle radius distribution shows that they follow a power-law with an exponent ≈ D (i.e. ≈3 for a 3D packing and ≈2 for 2D). Although the algorithm intrinsically guarantees coordination numbers of at least 4 in 3D and 3 in 2D, the coordination numbers realized in the generated packings can be significantly higher, reaching beyond 50 if the range of particle radii is sufficiently large. Even for relatively small ranges of particle sizes (e.g. Rmin = 0.5Rmax) the maximum coordination number may exceed 10. The degree of isotropy of the generated sphere packing is also analysed in both 2D and 3D, by measuring the distribution of orientations of vectors joining the centres of adjacent particles. If the range of particle sizes is small, the packing algorithm yields moderate anisotropy approaching that expected for a face-centred cubic packing of equal-sized particles. However, once Rmin Python[3] scripting language and provides the capacity to
Lin, Chao; Shen, Xueju; Li, Zengyan
2013-07-01
The key space of phase encryption algorithm using discrete random phase mask is investigated by numerical simulation in this paper. Random phase mask with finite and discrete phase levels is considered as the core component in most practical optical encryption architectures. The key space analysis is based on the design criteria of discrete random phase mask. The role of random amplitude mask and random phase mask in optical encryption system is identified from the perspective of confusion and diffusion. The properties of discrete random phase mask in a practical double random phase encoding scheme working in both amplitude encoding (AE) and phase encoding (PE) modes are comparably analyzed. The key space of random phase encryption algorithm is evaluated considering both the encryption quality and the brute-force attack resistibility. A method for enlarging the key space of phase encryption algorithm is also proposed to enhance the security of optical phase encryption techniques.
Czech Academy of Sciences Publication Activity Database
Axelsson, Owe; Blaheta, Radim; Byczanski, Petr
2012-01-01
Roč. 15, č. 4 (2012), s. 191-207 ISSN 1432-9360 R&D Projects: GA MŠk ED1.1.00/02.0070 Institutional support: RVO:68145535 Keywords : poroelasticity * saddle point matrices * preconditioning * stability of discretization Subject RIV: BA - General Mathematics http://link.springer.com/article/10.1007/s00791-013-0209-0
On the Discrete-Time Geo/G/1 Queue with Vacations in Random Environment
Directory of Open Access Journals (Sweden)
Jianjun Li
2016-01-01
Full Text Available A discrete-time Geo/G/1 queue with vacations in random environment is analyzed. Using the method of supplementary variable, we give the probability generating function (PGF of the stationary queue length distribution at arbitrary epoch. The PGF of the stationary sojourn time distribution is also derived. And we present the various performance measures such as mean number of customers in the system, mean length of the type-i cycle, and mean time that the system resides in phase 0. In addition, we show that the M/G/1 queue with vacations in random environment can be approximated by its discrete-time counterpart. Finally, we present some special cases of the model and numerical examples.
Anderson localization for 2D discrete Schrödinger operator with random vector potential
Klopp, F
2002-01-01
We prove the Anderson localization near the bottom of the spectrum for two dimensional discrete Schr{\\"o}dinger operators with a class of random vector potentials and no scalar potentials. Main lemmas are the Lifshitz tail and the Wegner estimate on the integrated density of states. Then, the Anderson localization, i.e., the pure point spectrum with exponentially decreasing eigenfunctions, is proved by the standard multiscale argument.
A new approach of stochastic dominance for ranking transformations on the discrete random variable
Gao, Jianwei; Zhao, Feng
2016-01-01
This paper develops some new stochastic dominance (SD) rules for ranking transformations on a random variable, which is the first time to study ranking approach for transformations on the discrete framework. By using the expected utility theory, the authors first present a sufficient condition for general transformations by first degree SD (FSD), and further develop it into the necessary and sufficient condition for the monotonic transformations. For the second degree SD (SSD) case, the autho...
Localization estimates for a random discrete wave equation at high frequency
International Nuclear Information System (INIS)
Faris, W.G.
1987-01-01
It is shown that at high frequencies matrix elements of the Green's function of a random discrete wave equation decay exponentially at long distances. This is the input to the proof of dense point spectrum with localized eigenfunctions in this frequency range. The proof uses techniques of Froehlich and Spencer. A sequence of renormalization transformations shows that large regions where wave propagation is easily maintained become increasingly sparse as resonance is approached
Chen, Z.; To, C. W. S.
2005-10-01
The extended stochastic central difference (ESCD) method is proposed as a viable alternative for computing linear responses of discretized multi-degrees-of-freedom (mdof) systems under narrow band stationary and nonstationary random disturbances. The method provides a means of controlling the center frequencies and bandwidths of narrow band stationary and nonstationary random excitation processes. It is suitable for larger-scale random response analysis of complicated structures idealized by the finite element method. Its additional important feature is that application of normal mode or complex normal mode analysis or direct numerical integration algorithms such as the fourth-order Runge-Kutta scheme is not required. Examples, including one of flow-induced vibration of a pipe containing a moving fluid are included to demonstrate: (1) the capability of the proposed method and difference between responses of discretized systems under narrow band and wide band random excitations, and (2) its accuracy and efficiency by way of comparison to the Monte Carlo simulation data. Generalization of the ESCD method for computation of responses of nonlinear mdof systems is presented in a companion paper.
Directory of Open Access Journals (Sweden)
Dongyan Chen
2015-01-01
Full Text Available This paper is concerned with the optimal Kalman filtering problem for a class of discrete stochastic systems with multiplicative noises and random two-step sensor delays. Three Bernoulli distributed random variables with known conditional probabilities are introduced to characterize the phenomena of the random two-step sensor delays which may happen during the data transmission. By using the state augmentation approach and innovation analysis technique, an optimal Kalman filter is constructed for the augmented system in the sense of the minimum mean square error (MMSE. Subsequently, the optimal Kalman filtering is derived for corresponding augmented system in initial instants. Finally, a simulation example is provided to demonstrate the feasibility and effectiveness of the proposed filtering method.
Discrete Moments of Zeta-Functions with respect to random and ergodic transformations
Srichan, Teerapat
2015-01-01
In the thesis discrete moments of the Riemann zeta-function and allied Dirichlet series are studied. In the first part the asymptotic value-distribution of zeta-functions is studied where the samples are taken from a Cauchy random walk on a vertical line inside the critical strip. Building on techniques by Lifshits and Weber analogous results for the Hurwitz zeta-function are derived. Using Atkinson’s dissection this is even generalized to Dirichlet L-functions associated with a primitiv...
A comparison of methods for representing random taste heterogeneity in discrete choice models
DEFF Research Database (Denmark)
Fosgerau, Mogens; Hess, Stephane
2009-01-01
This paper reports the findings of a systematic study using Monte Carlo experiments and a real dataset aimed at comparing the performance of various ways of specifying random taste heterogeneity in a discrete choice model. Specifically, the analysis compares the performance of two recent advanced...... distributions. Both approaches allow the researcher to increase the number of parameters as desired. The paper provides a range of evidence on the ability of the various approaches to recover various distributions from data. The two advanced approaches are comparable in terms of the likelihoods achieved...
Nonlinear Estimation of Discrete-Time Signals Under Random Observation Delay
International Nuclear Information System (INIS)
Caballero-Aguila, R.; Jimenez-Lopez, J. D.; Hermoso-Carazo, A.; Linares-Perez, J.; Nakamori, S.
2008-01-01
This paper presents an approximation to the nonlinear least-squares estimation problem of discrete-time stochastic signals using nonlinear observations with additive white noise which can be randomly delayed by one sampling time. The observation delay is modelled by a sequence of independent Bernoulli random variables whose values, zero or one, indicate that the real observation arrives on time or it is delayed and, hence, the available measurement to estimate the signal is not up-to-date. Assuming that the state-space model generating the signal is unknown and only the covariance functions of the processes involved in the observation equation are ready for use, a filtering algorithm based on linear approximations of the real observations is proposed.
Analysis of Discrete L2 Projection on Polynomial Spaces with Random Evaluations
Migliorati, Giovanni
2014-03-05
We analyze the problem of approximating a multivariate function by discrete least-squares projection on a polynomial space starting from random, noise-free observations. An area of possible application of such technique is uncertainty quantification for computational models. We prove an optimal convergence estimate, up to a logarithmic factor, in the univariate case, when the observation points are sampled in a bounded domain from a probability density function bounded away from zero and bounded from above, provided the number of samples scales quadratically with the dimension of the polynomial space. Optimality is meant in the sense that the weighted L2 norm of the error committed by the random discrete projection is bounded with high probability from above by the best L∞ error achievable in the given polynomial space, up to logarithmic factors. Several numerical tests are presented in both the univariate and multivariate cases, confirming our theoretical estimates. The numerical tests also clarify how the convergence rate depends on the number of sampling points, on the polynomial degree, and on the smoothness of the target function. © 2014 SFoCM.
Discrete gravity on random tensor network and holographic Rényi entropy
Han, Muxin; Huang, Shilin
2017-11-01
In this paper we apply the discrete gravity and Regge calculus to tensor networks and Anti-de Sitter/conformal field theory (AdS/CFT) correspondence. We construct the boundary many-body quantum state |Ψ〉 using random tensor networks as the holographic mapping, applied to the Wheeler-deWitt wave function of bulk Euclidean discrete gravity in 3 dimensions. The entanglement Rényi entropy of |Ψ〉 is shown to holographically relate to the on-shell action of Einstein gravity on a branch cover bulk manifold. The resulting Rényi entropy S n of |Ψ〉 approximates with high precision the Rényi entropy of ground state in 2-dimensional conformal field theory (CFT). In particular it reproduces the correct n dependence. Our results develop the framework of realizing the AdS3/CFT2 correspondence on random tensor networks, and provide a new proposal to approximate the CFT ground state.
Stable limits for sums of dependent infinite variance random variables
DEFF Research Database (Denmark)
Bartkiewicz, Katarzyna; Jakubowski, Adam; Mikosch, Thomas
2011-01-01
of these results are qualitative in the sense that the parameters of the limit distribution are expressed in terms of some limiting point process. In this paper we will be able to determine the parameters of the limiting stable distribution in terms of some tail characteristics of the underlying stationary...
The one-sample K-S test: TI-59 programs for discrete and continuous random variables
Brown, Douglas Warren; Barr, Donald R.
1981-01-01
Approved for public release, distribution unlimited The Kolmogorov-Smirnov (K-S) goodness-of-fi t test is a nonparametric test if the random variable is continuous. If the random variable is discrete the K-S test is not nonparametric. http://archive.org/details/onesamplekstestt00brow Lieutenant, Supply Corps, United States Navy
B.M. Craig (Benjamin); J.J. van Busschbach (Jan)
2009-01-01
textabstractABSTRACT: BACKGROUND: To present an episodic random utility model that unifies time trade-off and discrete choice approaches in health state valuation. METHODS: First, we introduce two alternative random utility models (RUMs) for health preferences: the episodic RUM and the more common
Migliorati, Giovanni
2015-08-28
We study the accuracy of the discrete least-squares approximation on a finite dimensional space of a real-valued target function from noisy pointwise evaluations at independent random points distributed according to a given sampling probability measure. The convergence estimates are given in mean-square sense with respect to the sampling measure. The noise may be correlated with the location of the evaluation and may have nonzero mean (offset). We consider both cases of bounded or square-integrable noise / offset. We prove conditions between the number of sampling points and the dimension of the underlying approximation space that ensure a stable and accurate approximation. Particular focus is on deriving estimates in probability within a given confidence level. We analyze how the best approximation error and the noise terms affect the convergence rate and the overall confidence level achieved by the convergence estimate. The proofs of our convergence estimates in probability use arguments from the theory of large deviations to bound the noise term. Finally we address the particular case of multivariate polynomial approximation spaces with any density in the beta family, including uniform and Chebyshev.
Directory of Open Access Journals (Sweden)
Ric A. Romero
2013-09-01
Full Text Available In certain applications, signal transmit power is adjusted in discrete levels. Moreover, interference powers themselves can be discretely random. For electronic intelligence applications, the authors refer to the signal to be collected as signal of interest (SoI. Thus, for a passive receiver, the resulting instantaneous SoI-to-interference power ratio (SIR in multiple interferences is a discrete random variable. This means signal detection or collection is not guaranteed. They proposed collection probability (CP as a metric when the SIR is random. In this study, the authors evaluate CP probabilistically and show CP against SIR threshold degradation and/or improvement as a function of increasing number of interferences, increasing signal power range and increasing distribution gain.
Discrete Choice Models with Random Parameters in R: The Rchoice Package
Directory of Open Access Journals (Sweden)
Mauricio Sarrias
2016-10-01
Full Text Available Rchoice is a package in R for estimating models with individual heterogeneity for both cross-sectional and panel (longitudinal data. In particular, the package allows binary, ordinal and count response, as well as continuous and discrete covariates. Individual heterogeneity is modeled by allowing the parameter associated with each observed variable (e.g., its coefficient to vary randomly across individuals according to some pre-specified distribution. Simulated maximum likelihood method is implemented for the estimation of the moments of the distributions. In addition, functions for plotting the conditional individual-specific coefficients and their confidence interval are provided. This article is a general description of Rchoice and all functionalities are illustrated using real databases.
Directory of Open Access Journals (Sweden)
Guitao Zhang
2014-01-01
Full Text Available The advertisement can increase the consumers demand; therefore it is one of the most important marketing strategies in the operations management of enterprises. This paper aims to analyze the impact of advertising investment on a discrete dynamic supply chain network which consists of suppliers, manufactures, retailers, and demand markets associated at different tiers under random demand. The impact of advertising investment will last several planning periods besides the current period due to delay effect. Based on noncooperative game theory, variational inequality, and Lagrange dual theory, the optimal economic behaviors of the suppliers, the manufactures, the retailers, and the consumers in the demand markets are modeled. In turn, the supply chain network equilibrium model is proposed and computed by modified project contraction algorithm with fixed step. The effectiveness of the model is illustrated by numerical examples, and managerial insights are obtained through the analysis of advertising investment in multiple periods and advertising delay effect among different periods.
Zhu, Guangpu
2018-01-26
In this paper, a fully discrete scheme which considers temporal and spatial discretizations is presented for the coupled Cahn-Hilliard equation in conserved form with the dynamic contact line condition and the Navier-Stokes equation with the generalized Navier boundary condition. Variable densities and viscosities are incorporated in this model. A rigorous proof of energy stability is provided for the fully discrete scheme based on a semi-implicit temporal discretization and a finite difference method on the staggered grids for the spatial discretization. A splitting method based on the pressure stabilization is implemented to solve the Navier-Stokes equation, while the stabilization approach is also used for the Cahn-Hilliard equation. Numerical results in both 2-D and 3-D demonstrate the accuracy, efficiency and decaying property of discrete energy of the proposed scheme.
Discrete random distribution of source dopants in nanowire tunnel transistors (TFETs)
Sylvia, Somaia; Abul Khayer, M.; Alam, Khairul; Park, Hong-Hyun; Klimeck, Gerhard; Lake, Roger
2013-03-01
InAs and InSb nanowire (NW) tunnel field effect transistors (TFETs) require highly degenerate source doping to support the high electric fields in the tunnel region. For a target on-current of 1 μA , the doping requirement may be as high as 1 . 5 ×1020cm-3 in a NW with diameter as low as 4 nm. The small size of these devices demand that the dopants near tunneling region be treated discretely. Therefore, the effects resulting from the random distribution of dopant atoms in the source of a TFET are studied for 30 test devices. Comparing with the transfer characteristics of the same device simulated with a continuum doping model, our results show (1) a spread of I - V toward the positive gate voltage axis, (2) the same average threshold voltage, (3) an average 62% reduction in the on current, and (4) a slight degradation of the subthreshold slope. Random fluctuations in both the number and placement of dopants will be discussed. Also, as the channel length is scaled down, direct tunneling through the channel starts limiting the device performance. Therefore, a comparison of materials is also performed, showing their ability to block direct tunneling for sub-10 nm channel FETs and TFETs. This work was supported in part by the Center on Functional Engineered Nano Architectonics and the Materials, Structures and Devices Focus Center, under the Focus Center Research Program, and by the National Science Foundation under Grant OCI-0749140
Stable Parameter Estimation for Autoregressive Equations with Random Coefficients
Directory of Open Access Journals (Sweden)
V. B. Goryainov
2014-01-01
Full Text Available In recent yearsthere has been a growing interest in non-linear time series models. They are more flexible than traditional linear models and allow more adequate description of real data. Among these models a autoregressive model with random coefficients plays an important role. It is widely used in various fields of science and technology, for example, in physics, biology, economics and finance. The model parameters are the mean values of autoregressive coefficients. Their evaluation is the main task of model identification. The basic method of estimation is still the least squares method, which gives good results for Gaussian time series, but it is quite sensitive to even small disturbancesin the assumption of Gaussian observations. In this paper we propose estimates, which generalize the least squares estimate in the sense that the quadratic objective function is replaced by an arbitrary convex and even function. Reasonable choice of objective function allows you to keep the benefits of the least squares estimate and eliminate its shortcomings. In particular, you can make it so that they will be almost as effective as the least squares estimate in the Gaussian case, but almost never loose in accuracy with small deviations of the probability distribution of the observations from the Gaussian distribution.The main result is the proof of consistency and asymptotic normality of the proposed estimates in the particular case of the one-parameter model describing the stationary process with finite variance. Another important result is the finding of the asymptotic relative efficiency of the proposed estimates in relation to the least squares estimate. This allows you to compare the two estimates, depending on the probability distribution of innovation process and of autoregressive coefficients. The results can be used to identify an autoregressive process, especially with nonGaussian nature, and/or of autoregressive processes observed with gross
Ostashev, Vladimir E; Wilson, D Keith; Muhlestein, Michael B; Attenborough, Keith
2018-02-01
Although sound propagation in a forest is important in several applications, there are currently no rigorous yet computationally tractable prediction methods. Due to the complexity of sound scattering in a forest, it is natural to formulate the problem stochastically. In this paper, it is demonstrated that the equations for the statistical moments of the sound field propagating in a forest have the same form as those for sound propagation in a turbulent atmosphere if the scattering properties of the two media are expressed in terms of the differential scattering and total cross sections. Using the existing theories for sound propagation in a turbulent atmosphere, this analogy enables the derivation of several results for predicting forest acoustics. In particular, the second-moment parabolic equation is formulated for the spatial correlation function of the sound field propagating above an impedance ground in a forest with micrometeorology. Effective numerical techniques for solving this equation have been developed in atmospheric acoustics. In another example, formulas are obtained that describe the effect of a forest on the interference between the direct and ground-reflected waves. The formulated correspondence between wave propagation in discrete and continuous random media can also be used in other fields of physics.
Calibration of Discrete Random Walk (DRW) Model via G.I Taylor's Dispersion Theory
Javaherchi, Teymour; Aliseda, Alberto
2012-11-01
Prediction of particle dispersion in turbulent flows is still an important challenge with many applications to environmental, as well as industrial, fluid mechanics. Several models of dispersion have been developed to predict particle trajectories and their relative velocities, in combination with a RANS-based simulation of the background flow. The interaction of the particles with the velocity fluctuations at different turbulent scales represents a significant difficulty in generalizing the models to the wide range of flows where they are used. We focus our attention on the Discrete Random Walk (DRW) model applied to flow in a channel, particularly to the selection of eddies lifetimes as realizations of a Poisson distribution with a mean value proportional to κ / ɛ . We present a general method to determine the constant of this proportionality by matching the DRW model dispersion predictions for fluid element and particle dispersion to G.I Taylor's classical dispersion theory. This model parameter is critical to the magnitude of predicted dispersion. A case study of its influence on sedimentation of suspended particles in a tidal channel with an array of Marine Hydrokinetic (MHK) turbines highlights the dependency of results on this time scale parameter. Support from US DOE through the Northwest National Marine Renewable Energy Center, a UW-OSU partnership.
Bao, Haibo; Cao, Jinde
2011-01-01
This paper is concerned with the state estimation problem for a class of discrete-time stochastic neural networks (DSNNs) with random delays. The effect of both variation range and distribution probability of the time delay are taken into account in the proposed approach. The stochastic disturbances are described in terms of a Brownian motion and the time-varying delay is characterized by introducing a Bernoulli stochastic variable. By employing a Lyapunov-Krasovskii functional, sufficient delay-distribution-dependent conditions are established in terms of linear matrix inequalities (LMIs) that guarantee the existence of the state estimator which can be checked readily by the Matlab toolbox. The main feature of the results obtained in this paper is that they are dependent on not only the bound but also the distribution probability of the time delay, and we obtain a larger allowance variation range of the delay, hence our results are less conservative than the traditional delay-independent ones. One example is given to illustrate the effectiveness of the proposed result. Copyright © 2010 Elsevier Ltd. All rights reserved.
Certain theories of multiple scattering in random media of discrete scatterers
International Nuclear Information System (INIS)
Olsen, R.L.; Kharadly, M.M.Z.; Corr, D.G.
1976-01-01
New information is presented on the accuracy of the heuristic approximations in two important theories of multiple scattering in random media of discrete scatterers: Twersky's ''free-space'' and ''two-space scatterer'' formalisms. Two complementary approaches, based primarily on a one-dimensional model and the one-dimensional forms of the theories, are used. For scatterer distributions of low average density, the ''heuristic'' asymptotic forms for the coherent field and the incoherent intensity are compared with asymptotic forms derived from a systematic analysis of the multiple scattering processes. For distributions of higher density, both in the average number of scatterers per wavelength and in the degree of packing of finite-size scatterers, the analysis is carried out ''experimentally'' by means of a Monte Carlo computer simulation. Approximate series expressions based on the systematic approach are numerically evaluated along with the heuristic expressions. The comparison (for both forward- and back-scattered field moments) is made for the worst-case conditions of strong multiple scattering for which the theories have not previously been evaluated. Several significant conclusions are drawn which have certain practical implications: in application of the theories to describe some of the scattering phenomena which occur in the troposphere, and in the further evaluation of the theories using experiments on physical models
Random regret-based discrete-choice modelling: an application to healthcare.
de Bekker-Grob, Esther W; Chorus, Caspar G
2013-07-01
A new modelling approach for analysing data from discrete-choice experiments (DCEs) has been recently developed in transport economics based on the notion of regret minimization-driven choice behaviour. This so-called Random Regret Minimization (RRM) approach forms an alternative to the dominant Random Utility Maximization (RUM) approach. The RRM approach is able to model semi-compensatory choice behaviour and compromise effects, while being as parsimonious and formally tractable as the RUM approach. Our objectives were to introduce the RRM modelling approach to healthcare-related decisions, and to investigate its usefulness in this domain. Using data from DCEs aimed at determining valuations of attributes of osteoporosis drug treatments and human papillomavirus (HPV) vaccinations, we empirically compared RRM models, RUM models and Hybrid RUM-RRM models in terms of goodness of fit, parameter ratios and predicted choice probabilities. In terms of model fit, the RRM model did not outperform the RUM model significantly in the case of the osteoporosis DCE data (p = 0.21), whereas in the case of the HPV DCE data, the Hybrid RUM-RRM model outperformed the RUM model (p implied by the two models can vary substantially. Differences in model fit between RUM, RRM and Hybrid RUM-RRM were found to be small. Although our study did not show significant differences in parameter ratios, the RRM and Hybrid RUM-RRM models did feature considerable differences in terms of the trade-offs implied by these ratios. In combination, our results suggest that RRM and Hybrid RUM-RRM modelling approach hold the potential of offering new and policy-relevant insights for health researchers and policy makers.
Thomas, D.L.; Johnson, D.; Griffith, B.
2006-01-01
Modeling the probability of use of land units characterized by discrete and continuous measures, we present a Bayesian random-effects model to assess resource selection. This model provides simultaneous estimation of both individual- and population-level selection. Deviance information criterion (DIC), a Bayesian alternative to AIC that is sample-size specific, is used for model selection. Aerial radiolocation data from 76 adult female caribou (Rangifer tarandus) and calf pairs during 1 year on an Arctic coastal plain calving ground were used to illustrate models and assess population-level selection of landscape attributes, as well as individual heterogeneity of selection. Landscape attributes included elevation, NDVI (a measure of forage greenness), and land cover-type classification. Results from the first of a 2-stage model-selection procedure indicated that there is substantial heterogeneity among cow-calf pairs with respect to selection of the landscape attributes. In the second stage, selection of models with heterogeneity included indicated that at the population-level, NDVI and land cover class were significant attributes for selection of different landscapes by pairs on the calving ground. Population-level selection coefficients indicate that the pairs generally select landscapes with higher levels of NDVI, but the relationship is quadratic. The highest rate of selection occurs at values of NDVI less than the maximum observed. Results for land cover-class selections coefficients indicate that wet sedge, moist sedge, herbaceous tussock tundra, and shrub tussock tundra are selected at approximately the same rate, while alpine and sparsely vegetated landscapes are selected at a lower rate. Furthermore, the variability in selection by individual caribou for moist sedge and sparsely vegetated landscapes is large relative to the variability in selection of other land cover types. The example analysis illustrates that, while sometimes computationally intense, a
Shared Care in Monitoring Stable Glaucoma Patients: A Randomized Controlled Trial
Holtzer-Goor, Kim M.; van Vliet, Ellen J.; van Sprundel, Esther; Plochg, Thomas; Koopmanschap, Marc A.; Klazinga, Niek S.; Lemij, Hans G.
2016-01-01
Comparing the quality of care provided by a hospital-based shared care glaucoma follow-up unit with care as usual. This randomized controlled trial included stable glaucoma patients and patients at risk for developing glaucoma. Patients in the Usual Care group (n=410) were seen by glaucoma
Fan, Xiaozheng; Wang, Yan; Hu, Manfeng
2016-01-01
In this paper, the fuzzy [Formula: see text] output-feedback control problem is investigated for a class of discrete-time T-S fuzzy systems with channel fadings, sector nonlinearities, randomly occurring interval delays (ROIDs) and randomly occurring nonlinearities (RONs). A series of variables of the randomly occurring phenomena obeying the Bernoulli distribution is used to govern ROIDs and RONs. Meanwhile, the measurement outputs are subject to the sector nonlinearities ( i.e. the sensor saturations) and we assume the system output is [Formula: see text], [Formula: see text]. The L th-order Rice model is utilized to describe the phenomenon of channel fadings by setting different values of the channel coefficients. The aim of this work is to deal with the problem of designing a full-order dynamic fuzzy [Formula: see text] output-feedback controller such that the fuzzy closed-loop system is exponentially mean-square stable and the [Formula: see text] performance constraint is satisfied, by means of a combination of Lyapunov stability theory and stochastic analysis along with LMI methods. The proposed fuzzy controller parameters are derived by solving a convex optimization problem via the semidefinite programming technique. Finally, a numerical simulation is given to illustrate the feasibility and effectiveness of the proposed design technique.
Numerically Stable Evaluation of Moments of Random Gram Matrices With Applications
Elkhalil, Khalil
2017-07-31
This paper focuses on the computation of the positive moments of one-side correlated random Gram matrices. Closed-form expressions for the moments can be obtained easily, but numerical evaluation thereof is prone to numerical stability, especially in high-dimensional settings. This letter provides a numerically stable method that efficiently computes the positive moments in closed-form. The developed expressions are more accurate and can lead to higher accuracy levels when fed to moment based-approaches. As an application, we show how the obtained moments can be used to approximate the marginal distribution of the eigenvalues of random Gram matrices.
International Nuclear Information System (INIS)
Vanderbei, Robert J.; Pınar, Mustafa Ç.; Bozkaya, Efe B.
2013-01-01
An American option (or, warrant) is the right, but not the obligation, to purchase or sell an underlying equity at any time up to a predetermined expiration date for a predetermined amount. A perpetual American option differs from a plain American option in that it does not expire. In this study, we solve the optimal stopping problem of a perpetual American option (both call and put) in discrete time using linear programming duality. Under the assumption that the underlying stock price follows a discrete time and discrete state Markov process, namely a geometric random walk, we formulate the pricing problem as an infinite dimensional linear programming (LP) problem using the excessive-majorant property of the value function. This formulation allows us to solve complementary slackness conditions in closed-form, revealing an optimal stopping strategy which highlights the set of stock-prices where the option should be exercised. The analysis for the call option reveals that such a critical value exists only in some cases, depending on a combination of state-transition probabilities and the economic discount factor (i.e., the prevailing interest rate) whereas it ceases to be an issue for the put.
Energy Technology Data Exchange (ETDEWEB)
Vanderbei, Robert J., E-mail: rvdb@princeton.edu [Princeton University, Department of Operations Research and Financial Engineering (United States); P Latin-Small-Letter-Dotless-I nar, Mustafa C., E-mail: mustafap@bilkent.edu.tr [Bilkent University, Department of Industrial Engineering (Turkey); Bozkaya, Efe B. [Sabanc Latin-Small-Letter-Dotless-I University, Faculty of Administrative Sciences (Turkey)
2013-02-15
An American option (or, warrant) is the right, but not the obligation, to purchase or sell an underlying equity at any time up to a predetermined expiration date for a predetermined amount. A perpetual American option differs from a plain American option in that it does not expire. In this study, we solve the optimal stopping problem of a perpetual American option (both call and put) in discrete time using linear programming duality. Under the assumption that the underlying stock price follows a discrete time and discrete state Markov process, namely a geometric random walk, we formulate the pricing problem as an infinite dimensional linear programming (LP) problem using the excessive-majorant property of the value function. This formulation allows us to solve complementary slackness conditions in closed-form, revealing an optimal stopping strategy which highlights the set of stock-prices where the option should be exercised. The analysis for the call option reveals that such a critical value exists only in some cases, depending on a combination of state-transition probabilities and the economic discount factor (i.e., the prevailing interest rate) whereas it ceases to be an issue for the put.
DEFF Research Database (Denmark)
Egstrup, K
1988-01-01
In a randomized double-blind study, treatment with either metoprolol, nifedipine, or their combination was compared for effects on ischemic variables and heart rate obtained during ambulatory monitoring in 42 patients with chronic stable angina. All patients had severe chronic stable angina...... of at least 6 months' duration despite medical treatment, and exhibited coronary artery stenosis of 75% in one or more coronary arteries. Metoprolol reduced the frequency of total (p less than 0.01) and asymptomatic ischemic episodes (p less than 0.05), the duration of ischemia (p less than 0.......05), and the ischemic burden (p less than 0.05), which contrasted to the lack of any similar significant effect during nifedipine monotherapy. During combination therapy, there was a tendency to further improvement, which did not reach statistical significance compared with metoprolol monotherapy. Heart rate...
Directory of Open Access Journals (Sweden)
Maurice R. Kibler
2010-07-01
Full Text Available We propose a group-theoretical approach to the generalized oscillator algebra Aκ recently investigated in J. Phys. A: Math. Theor. 2010, 43, 115303. The case κ ≥ 0 corresponds to the noncompact group SU(1,1 (as for the harmonic oscillator and the Pöschl-Teller systems while the case κ < 0 is described by the compact group SU(2 (as for the Morse system. We construct the phase operators and the corresponding temporally stable phase eigenstates for Aκ in this group-theoretical context. The SU(2 case is exploited for deriving families of mutually unbiased bases used in quantum information. Along this vein, we examine some characteristics of a quadratic discrete Fourier transform in connection with generalized quadratic Gauss sums and generalized Hadamard matrices.
THE COVARIATION FUNCTION FOR SYMMETRIC &ALPHA;-STABLE RANDOM VARIABLES WITH FINITE FIRST MOMENTS
Directory of Open Access Journals (Sweden)
Dedi Rosadi
2012-05-01
Full Text Available In this paper, we discuss a generalized dependence measure which is designed to measure dependence of two symmetric α-stable random variables with finite mean(1<α<=2 and contains the covariance function as the special case (when α=2. Weshortly discuss some basic properties of the function and consider several methods to estimate the function and further investigate the numerical properties of the estimatorusing the simulated data. We show how to apply this function to measure dependence of some stock returns on the composite index LQ45 in Indonesia Stock Exchange.
Random First-Order Linear Discrete Models and Their Probabilistic Solution: A Comprehensive Study
Directory of Open Access Journals (Sweden)
M.-C. Casabán
2016-01-01
Full Text Available This paper presents a complete stochastic solution represented by the first probability density function for random first-order linear difference equations. The study is based on Random Variable Transformation method. The obtained results are given in terms of the probability density functions of the data, namely, initial condition, forcing term, and diffusion coefficient. To conduct the study, all possible cases regarding statistical dependence of the random input parameters are considered. A complete collection of illustrative examples covering all the possible scenarios is provided.
Analysis and Adaptive Control of a Discrete-Time Single-Server Network with Random Routing
National Research Council Canada - National Science Library
Makowski, Armand M; Shwartz, Adam
1989-01-01
.... Customers arrive in i.i.d batches and are served according to a server allocation policy. Upon completing service, customers either leave the system or are routed instantaneously to another queue according to some random mechnism...
Analysis and Adaptive Control of a Discrete-Time Single-Server Network with Random Routing
National Research Council Canada - National Science Library
Makowski, Armand M; Shwartz, Adam
1989-01-01
.... Customers arrive in i.i,d batches and are served according to a server allocation policy. Upon completing service, customers either leave the system or are routed instantaneously to another queue according to some random mechanism...
International Nuclear Information System (INIS)
Lee, T.D.
1985-01-01
This paper reviews the role of time throughout all phases of mechanics: classical mechanics, non-relativistic quantum mechanics, and relativistic quantum theory. As an example of the relativistic quantum field theory, the case of a massless scalar field interacting with an arbitrary external current is discussed. The comparison between the new discrete theory and the usual continuum formalism is presented. An example is given of a two-dimensional random lattice and its duel. The author notes that there is no evidence that the discrete mechanics is more appropriate than the usual continuum mechanics
Non-uniform approximations for sums of discrete m-dependent random variables
Vellaisamy, P.; Cekanavicius, V.
2013-01-01
Non-uniform estimates are obtained for Poisson, compound Poisson, translated Poisson, negative binomial and binomial approximations to sums of of m-dependent integer-valued random variables. Estimates for Wasserstein metric also follow easily from our results. The results are then exemplified by the approximation of Poisson binomial distribution, 2-runs and $m$-dependent $(k_1,k_2)$-events.
Abid, Najmul; Mirkhalaf, Mohammad; Barthelat, Francois
2018-03-01
Natural materials such as nacre, collagen, and spider silk are composed of staggered stiff and strong inclusions in a softer matrix. This type of hybrid microstructure results in remarkable combinations of stiffness, strength, and toughness and it now inspires novel classes of high-performance composites. However, the analytical and numerical approaches used to predict and optimize the mechanics of staggered composites often neglect statistical variations and inhomogeneities, which may have significant impacts on modulus, strength, and toughness. Here we present an analysis of localization using small representative volume elements (RVEs) and large scale statistical volume elements (SVEs) based on the discrete element method (DEM). DEM is an efficient numerical method which enabled the evaluation of more than 10,000 microstructures in this study, each including about 5,000 inclusions. The models explore the combined effects of statistics, inclusion arrangement, and interface properties. We find that statistical variations have a negative effect on all properties, in particular on the ductility and energy absorption because randomness precipitates the localization of deformations. However, the results also show that the negative effects of random microstructures can be offset by interfaces with large strain at failure accompanied by strain hardening. More specifically, this quantitative study reveals an optimal range of interface properties where the interfaces are the most effective at delaying localization. These findings show how carefully designed interfaces in bioinspired staggered composites can offset the negative effects of microstructural randomness, which is inherent to most current fabrication methods.
Wang, Qingzhu; Chen, Xiaoming; Zhu, Yihai
2017-09-01
Existing image compression and encryption methods have several shortcomings: they have low reconstruction accuracy and are unsuitable for three-dimensional (3D) images. To overcome these limitations, this paper proposes a tensor-based approach adopting tensor compressive sensing and tensor discrete fractional random transform (TDFRT). The source video images are measured by three key-controlled sensing matrices. Subsequently, the resulting tensor image is further encrypted using 3D cat map and the proposed TDFRT, which is based on higher-order singular value decomposition. A multiway projection algorithm is designed to reconstruct the video images. The proposed algorithm can greatly reduce the data volume and improve the efficiency of the data transmission and key distribution. The simulation results validate the good compression performance, efficiency, and security of the proposed algorithm.
Calcipotriol versus coal tar: a prospective randomized study in stable plaque psoriasis
Energy Technology Data Exchange (ETDEWEB)
Sharma, V.; Kaur, I.; Kumar, B. [Postgraduate Institute of Medicinal Education & Research, Chandigarh (India)
2003-10-01
Topical therapies are the first line of treatment for patients with stable plaque psoriasis (SPP) affecting a limited body surface area. Very few trials comparing newer agents, such as 0.005% topical calcipotriol, with conventional modes of therapy, such as coal tar ointment, have been reported. A prospective, right-left randomized, investigator-blinded study with a 12-week treatment period and an 8-week follow-up period was performed. It was found that 0.005% calcipotriol ointment produced a faster initial response and had better cosmetic acceptability in patients, although after a long period of treatment, i.e. 12 weeks, 5% coal tar ointment had comparable efficacy. There was no statistically significant difference in the relapse rates between the two modalities.
Random Graphs Associated to Some Discrete and Continuous Time Preferential Attachment Models
Pachon, Angelica; Polito, Federico; Sacerdote, Laura
2016-03-01
We give a common description of Simon, Barabási-Albert, II-PA and Price growth models, by introducing suitable random graph processes with preferential attachment mechanisms. Through the II-PA model, we prove the conditions for which the asymptotic degree distribution of the Barabási-Albert model coincides with the asymptotic in-degree distribution of the Simon model. Furthermore, we show that when the number of vertices in the Simon model (with parameter α ) goes to infinity, a portion of them behave as a Yule model with parameters (λ ,β ) = (1-α ,1), and through this relation we explain why asymptotic properties of a random vertex in Simon model, coincide with the asymptotic properties of a random genus in Yule model. As a by-product of our analysis, we prove the explicit expression of the in-degree distribution for the II-PA model, given without proof in Newman (Contemp Phys 46:323-351, 2005). References to traditional and recent applications of the these models are also discussed.
Very early feeding in stable small for gestational age preterm infants: a randomized clinical trial.
Arnon, Shmuel; Sulam, Daniella; Konikoff, Fred; Regev, Rivka H; Litmanovitz, Ita; Naftali, Timna
2013-01-01
To examine the effect of initiating very early feeding on time-to-reach full feeding in stable, small for gestational age (SGA) preterm infants. Preterm infants with gestational age below 37 weeks and birth weight below the 10(th) percentile were randomly allocated to a very early (within 24 hours of birth) feeding regimen or delayed (after 24 hours of birth) feeding. All infants had in utero evidence of absent or reverse diastolic flow. Infants unable to start early feeding were excluded. Time-to-reach full feeding, feeding progression, and related morbidity were compared. Electrogastrography (EGG) was used to measure pre- and postprandial gastric motility on the second and seventh day after feeding initiation. Sixty infants were included in the study, 30 in each group. Infants included in the very early feeding regimen achieved full enteral feeding sooner than controls (98±80-157 vs. 172±123-261 hours of age, respectively; p= 0.004) and were discharged home earlier (p=0.04). No necrotizing enterocolitis (NEC) was documented in both study groups. Gastric motility was improved at day seven after feeding initiation in both study groups, with no difference between groups. Stable SGA preterm infants on a very early feeding regimen achieved full enteral feeding and were discharged home significantly earlier than those on a delayed regimen, with no excess morbidity. Copyright © 2013 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.
Tribby, Calvin P; Miller, Harvey J; Brown, Barbara B; Werner, Carol M; Smith, Ken R
2017-11-01
Walking is a form of active transportation with numerous benefits, including better health outcomes, lower environmental impacts and stronger communities. Understanding built environmental associations with walking behavior is a key step towards identifying design features that support walking. Human mobility data available through GPS receivers and cell phones, combined with high resolution walkability data, provide a rich source of georeferenced data for analyzing environmental associations with walking behavior. However, traditional techniques such as route choice models have difficulty with highly dimensioned data. This paper develops a novel combination of a data-driven technique with route choice modeling for leveraging walkability audits. Using data from a study in Salt Lake City, Utah, USA, we apply the data-driven technique of random forests to select variables for use in walking route choice models. We estimate data-driven route choice models and theory-driven models based on predefined walkability dimensions. Results indicate that the random forest technique selects variables that dramatically improve goodness of fit of walking route choice models relative to models based on predefined walkability dimensions. We compare the theory-driven and data-driven walking route choice models based on interpretability and policy relevance.
van Zon, Alice; Smulders, Yvette E; Stegeman, Inge; Ramakers, Geerte G J; Kraaijenga, Veronique J C; Koenraads, Simone P C; Zanten, Gijsbert A Van; Rinia, Albert B; Stokroos, Robert J; Free, Rolien H; Frijns, Johan H M; Huinck, Wendy J; Mylanus, Emmanuel A M; Tange, Rinze A; Smit, Adriana L; Thomeer, Hans G X M; Topsakal, Vedat; Grolman, Wilko
2017-05-01
To investigate hearing capabilities and self-reported benefits of simultaneous bilateral cochlear implantation (BiCI) compared with unilateral cochlear implantation (UCI) after a 2-year follow-up and to evaluate the learning effect of cochlear implantees over time. Multicenter randomized controlled trial. Thirty-eight postlingually deafened adults were included in this study and randomly allocated to either UCI or simultaneous BiCI. Our primary outcome was speech intelligibility in noise, with speech and noise coming from straight ahead (Utrecht-Sentence Test with Adaptive Randomized Roving levels). Secondary outcomes were speech intelligibility in noise with spatially separated sources, speech intelligibility in silence (Dutch phoneme test), localization capabilities and self-reported benefits assessed with different quality of hearing and quality of life (QoL) questionnaires. This article describes the results after 2 years of follow-up. We found comparable results for the UCI and simultaneous BiCI group, when speech and noise were both presented from straight ahead. Patients in the BiCI group performed significantly better than patients in the UCI group, when speech and noise came from different directions (P = .01). Furthermore, their localization capabilities were significantly better. These results were consistent with patients' self-reported hearing capabilities, but not with the questionnaires regarding QoL. We found no significant differences on any of the subjective and objective reported outcomes between the 1-year and 2-year follow-up. This study demonstrates important benefits of simultaneous BiCI compared with UCI that remain stable over time. Bilaterally implanted patients benefit significantly in difficult everyday listening situations such as when speech and noise come from different directions. Furthermore, bilaterally implanted patients are able to localize sounds, which is impossible for unilaterally implanted patients. 1b Laryngoscope, 127
Reliable H∞ control of discrete-time systems against random intermittent faults
Tao, Yuan; Shen, Dong; Fang, Mengqi; Wang, Youqing
2016-07-01
A passive fault-tolerant control strategy is proposed for systems subject to a novel kind of intermittent fault, which is described by a Bernoulli distributed random variable. Three cases of fault location are considered, namely, sensor fault, actuator fault, and both sensor and actuator faults. The dynamic feedback controllers are designed not only to stabilise the fault-free system, but also to guarantee an acceptable performance of the faulty system. The robust H∞ performance index is used to evaluate the effectiveness of the proposed control scheme. In terms of linear matrix inequality, the sufficient conditions of the existence of controllers are given. An illustrative example indicates the effectiveness of the proposed fault-tolerant control method.
A randomized controlled trial of acupuncture in stable ischemic heart disease patients.
Mehta, Puja K; Polk, Donna M; Zhang, Xiao; Li, Ning; Painovich, Jeannette; Kothawade, Kamlesh; Kirschner, Joan; Qiao, Yi; Ma, Xiuling; Chen, Yii-Der Ida; Brantman, Anna; Shufelt, Chrisandra; Minissian, Margo; Merz, C Noel Bairey
2014-09-20
Heart rate variability (HRV) is reduced in stable ischemic heart disease (SIHD) patients and is associated with sudden cardiac death (SCD). We evaluated the impact of traditional acupuncture (TA) on cardiac autonomic function measured by HRV in SIHD patients. We conducted a randomized controlled study of TA, sham acupuncture (SA), and waiting control (WC) in 151 SIHD subjects. The TA group received needle insertion at acupuncture sites, the SA group received a sham at non-acupuncture sites, while the WC group received nothing. The TA and SA groups received 3 treatments/week for 12 weeks. 24-Hour, mental arithmetic stress, and cold pressor (COP) HRV was collected at entry and exit, along with BP, lipids, insulin resistance, hs-CRP, salivary cortisol, peripheral endothelial function by tonometry (PAT), and psychosocial variables. Mean age was 63 ± 10; 50% had prior myocardial infarction. Comparison of WC and SA groups demonstrated differences consistent with the unblinded WC status; therefore by design, the control groups were not merged. Exit mental stress HRV was higher in TA vs. SA for markers of parasympathetic tone (p ≤ 0.025), including a 17% higher vagal activity (p=0.008). There were no differences in exit 24-hour or COP HRV, BP, lipids, insulin resistance, hs-CRP, salivary cortisol, PAT, or psychosocial variables. TA results in intermediate effects on autonomic function in SIHD patients. TA effect on HRV may be clinically relevant and should be explored further. These data document feasibility and provide sample size estimation for a clinical trial of TA in SIHD patients for the prevention of SCD. We conducted a randomized, single-blind trial of traditional acupuncture (TA) vs. sham acupuncture (SA) vs waiting control (WC) in stable ischemic heart disease (SIHD) patients to evaluate cardiac autonomic function measured by heart rate variability (HRV). Exit mental stress HRV was higher in the TA compared to SA group for time and frequency domain markers of
Chkifa, Abdellah
2015-04-08
Motivated by the numerical treatment of parametric and stochastic PDEs, we analyze the least-squares method for polynomial approximation of multivariate functions based on random sampling according to a given probability measure. Recent work has shown that in the univariate case, the least-squares method is quasi-optimal in expectation in [A. Cohen, M A. Davenport and D. Leviatan. Found. Comput. Math. 13 (2013) 819–834] and in probability in [G. Migliorati, F. Nobile, E. von Schwerin, R. Tempone, Found. Comput. Math. 14 (2014) 419–456], under suitable conditions that relate the number of samples with respect to the dimension of the polynomial space. Here “quasi-optimal” means that the accuracy of the least-squares approximation is comparable with that of the best approximation in the given polynomial space. In this paper, we discuss the quasi-optimality of the polynomial least-squares method in arbitrary dimension. Our analysis applies to any arbitrary multivariate polynomial space (including tensor product, total degree or hyperbolic crosses), under the minimal requirement that its associated index set is downward closed. The optimality criterion only involves the relation between the number of samples and the dimension of the polynomial space, independently of the anisotropic shape and of the number of variables. We extend our results to the approximation of Hilbert space-valued functions in order to apply them to the approximation of parametric and stochastic elliptic PDEs. As a particular case, we discuss “inclusion type” elliptic PDE models, and derive an exponential convergence estimate for the least-squares method. Numerical results confirm our estimate, yet pointing out a gap between the condition necessary to achieve optimality in the theory, and the condition that in practice yields the optimal convergence rate.
Basiri-Moghadam, Mahdi; Basiri-Moghadam, Kokab; Kianmehr, Mojtaba; Jani, Somaye
2015-06-01
To evaluate the effects of massage therapy on transcutaneous bilirubin of stable preterm infants. The controlled clinical trial was conducted in 2014 at Shahid Hasheminejhad Hospital, Iran, and comprised preterm neonatal children in the neonatal intensive care unit. The newborns were divided into two groups of massage and control via random allocation. The children in the control group received the routine therapy whereas those in the massage group underwent the same four days of routine plus 20 minutes of massage twice a day. The transcutaneous bilirubin and the number of excretions of the newborns were noted from the first to the fourth day of the intervention and results were compared between the two groups. There were 40 newborns in the study l 20(50%) each in the two groups. There was a significant difference in the number of times of defecation (p=0.002) and in the level of bilirubin (p=0.003) between the groups with those in the massage group having a higher number of defecations as well as a lower level of transcutaneous bilirubin. Through massage therapy the bilirubin level in preterm newborns can be controlled and a need for phototherapy can also be delayed.
Directory of Open Access Journals (Sweden)
Debesh Jha
2017-01-01
Full Text Available Accurate diagnosis of pathological brain images is important for patient care, particularly in the early phase of the disease. Although numerous studies have used machine-learning techniques for the computer-aided diagnosis (CAD of pathological brain, previous methods encountered challenges in terms of the diagnostic efficiency owing to deficiencies in the choice of proper filtering techniques, neuroimaging biomarkers, and limited learning models. Magnetic resonance imaging (MRI is capable of providing enhanced information regarding the soft tissues, and therefore MR images are included in the proposed approach. In this study, we propose a new model that includes Wiener filtering for noise reduction, 2D-discrete wavelet transform (2D-DWT for feature extraction, probabilistic principal component analysis (PPCA for dimensionality reduction, and a random subspace ensemble (RSE classifier along with the K-nearest neighbors (KNN algorithm as a base classifier to classify brain images as pathological or normal ones. The proposed methods provide a significant improvement in classification results when compared to other studies. Based on 5×5 cross-validation (CV, the proposed method outperforms 21 state-of-the-art algorithms in terms of classification accuracy, sensitivity, and specificity for all four datasets used in the study.
Parashar, R.; Pickman, L. H.; Reeves, M. D.
2015-12-01
The Continuous Time Random Walk (CTRW) method provides a framework for modeling non-Fickian transport behavior through heterogeneous media by employing probability distributions to generate particle jump lengths and residence times spanning multiple orders of magnitude. In this work, we seek to formulate and parameterize a 2D CTRW directly from attributes of fracture networks with complex geometry. A Discrete Fracture Network (DFN) model is used to produce data on plume evolution over multiple spatial scales by synthetically generating a fracture network based on known fracture characteristics and conducting flow and particle tracking simulations under steady-state boundary conditions and flux-weighted particle migration. DFN Fracture segments, defined as the linear distance between two fracture intersections, are analyzed to define the distribution of jump lengths. The time for particles to migrate along these segments is recorded by the DFN model and is used to define a distribution of waiting times. These distributions provide a basis on which to formulate a CTRW to predict the migration of inert particles on a continuum of scales. The performance of the CTRW in simulating transport at multiple spatial scales is obtained by comparing spatial moments of the DFN plumes with CTRW solutions.
Pettersson, Per; Nordström, Jan; Doostan, Alireza
2016-02-01
We present a well-posed stochastic Galerkin formulation of the incompressible Navier-Stokes equations with uncertainty in model parameters or the initial and boundary conditions. The stochastic Galerkin method involves representation of the solution through generalized polynomial chaos expansion and projection of the governing equations onto stochastic basis functions, resulting in an extended system of equations. A relatively low-order generalized polynomial chaos expansion is sufficient to capture the stochastic solution for the problem considered. We derive boundary conditions for the continuous form of the stochastic Galerkin formulation of the velocity and pressure equations. The resulting problem formulation leads to an energy estimate for the divergence. With suitable boundary data on the pressure and velocity, the energy estimate implies zero divergence of the velocity field. Based on the analysis of the continuous equations, we present a semi-discretized system where the spatial derivatives are approximated using finite difference operators with a summation-by-parts property. With a suitable choice of dissipative boundary conditions imposed weakly through penalty terms, the semi-discrete scheme is shown to be stable. Numerical experiments in the laminar flow regime corroborate the theoretical results and we obtain high-order accurate results for the solution variables and the velocity divergence converges to zero as the mesh is refined.
Zhang, Hua; Zhang, Hong; Yang, Chao; Dai, Jiangyun; Yin, Jiajia; Xue, Hongyan; Feng, Guoying; Zhou, Shouhuan
2018-02-01
Construction of ultra-photo-stable coherent random laser based on liquid waveguide gain channels doped with boehmite nanosheets has been demonstrated. An Al plate uniformly coated with boehmite nanosheets was prepared by an alkali-treatment method and used as a scattering surface for the coherent random laser. Microcavity may be formed between these boehmite nanosheets owing to the strong optical feedback induced by the multiple light scattering. Many sharp peaks are observed in the emission spectra, and their laser thresholds are different, which confirms the feedback mechanism is coherent. The linewidth of the main peak at 571.74 nm is 0.28 nm, and the threshold of the main peak is about 4.96 mJ/cm2. Due to the fluidity of liquid waveguide gain medium, the photostability of this coherent random laser is better than the conventional solid state dye random lasers. The emission direction is well constrained by the waveguide effect within a certain angular range (±30°). This kind of coherent random laser can be applied in optical fluid lasers and photonic devices.
Prezel, Elea; Elie, Auréliane; Delaroche, Julie; Stoppin-Mellet, Virginie; Bosc, Christophe; Serre, Laurence; Fourest-Lieuvin, Anne; Andrieux, Annie; Vantard, Marylin; Arnal, Isabelle
2018-01-15
In neurons, microtubule networks alternate between single filaments and bundled arrays under the influence of effectors controlling their dynamics and organization. Tau is a microtubule bundler that stabilizes microtubules by stimulating growth and inhibiting shrinkage. The mechanisms by which tau organizes microtubule networks remain poorly understood. Here, we studied the self-organization of microtubules growing in the presence of tau isoforms and mutants. The results show that tau's ability to induce stable microtubule bundles requires two hexapeptides located in its microtubule-binding domain and is modulated by its projection domain. Site-specific pseudophosphorylation of tau promotes distinct microtubule organizations: stable single microtubules, stable bundles, or dynamic bundles. Disease-related tau mutations increase the formation of highly dynamic bundles. Finally, cryo-electron microscopy experiments indicate that tau and its variants similarly change the microtubule lattice structure by increasing both the protofilament number and lattice defects. Overall, our results uncover novel phosphodependent mechanisms governing tau's ability to trigger microtubule organization and reveal that disease-related modifications of tau promote specific microtubule organizations that may have a deleterious impact during neurodegeneration. © 2018 Prezel, Elie, et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).
Directory of Open Access Journals (Sweden)
Yurong Liu
2013-01-01
Full Text Available This paper is concerned with the leader-following consensus problem in mean-square for a class of discrete-time multiagent systems. The multiagent systems under consideration are the directed and contain arbitrary discrete time-delays. The communication links are assumed to be time-varying and stochastic. It is also assumed that some agents in the network are well informed and act as leaders, and the others are followers. By introducing novel Lyapunov functionals and employing some new analytical techniques, sufficient conditions are derived to guarantee the leader-following consensus in mean-square for the concerned multiagent systems, so that all the agents are steered to an anticipated state target. A numerical example is presented to illustrate the main results.
Solute dispersion for stable density-driven flow in randomly heterogeneous porous media
Dell'Oca, Aronne; Riva, Monica; Carrera, Jesus; Guadagnini, Alberto
2018-01-01
We present a theoretical investigation on the processes underpinning the reduced longitudinal spreading documented in stable variable density flows, as opposed to constant density settings, within heterogeneous porous media. We do so by decomposing velocity and pressure in terms of stationary and dynamic components. The former corresponds to the solution of the constant density flow problem, while the latter accounts for the effects induced by density variability. We focus on a stable flow configuration and analyze the longitudinal spread of saltwater injected from the bottom of a column formed by a heterogeneous porous medium initially fully saturated by freshwater. We adopt a perturbation expansion approach and derive the equations satisfied by section-averaged concentrations and their ensemble mean values. These formulations are respectively characterized by a single realization and an ensemble dispersive flux, which we determine through appropriate closure equations. The latter are solved via semi-analytical and numerical approaches. Our formulations and associated results enable us to discriminate the relative impact on the density-driven solute displacement of (a) covariance of the permeability of the porous medium, (b) cross-covariance between permeability and concentration, which is in turn linked to the coupling of flow and transport problems, and (c) cross-covariance between the dynamic and stationary velocities.
DEFF Research Database (Denmark)
Sørensen, John Aasted
2011-01-01
The objectives of Discrete Mathematics (IDISM2) are: The introduction of the mathematics needed for analysis, design and verification of discrete systems, including the application within programming languages for computer systems. Having passed the IDISM2 course, the student will be able...... to accomplish the following: -Understand and apply formal representations in discrete mathematics. -Understand and apply formal representations in problems within discrete mathematics. -Understand methods for solving problems in discrete mathematics. -Apply methods for solving problems in discrete mathematics......; construct a finite state machine for a given application. Apply these concepts to new problems. The teaching in Discrete Mathematics is a combination of sessions with lectures and students solving problems, either manually or by using Matlab. Furthermore a selection of projects must be solved and handed...
Stable switching of resistive random access memory on the nanotip array electrodes
Tsai, Kun-Tong
2016-09-13
The formation/rupture of conducting filaments (CFs) in resistive random access memory (ReRAM) materials tune the electrical conductivities non-volatilely and are largely affected by its material composition [1], internal configurations [2] and external environments [3,4]. Therefore, controlling repetitive formation/rupture of CF as well as the spatial uniformity of formed CF are fundamentally important for improving the resistive switching (RS) performance. In this context, we have shown that by adding a field initiator, typically a textured electrode, both performance and switching uniformity of ReRAMs can be improved dramatically [5]. In addition, despite its promising characteristics, the scalable fabrication and structural homogeneity of such nanostructured electrodes are still lacking or unattainable, making miniaturization of ReRAM devices an exceeding challenge. Here, we employ nanostructured electrode (nanotip arrays, extremely uniform) formed spontaneously via a self-organized process to improve the ZnO ReRAM switching characteristics.
Blattner, Clarissa Netto; Santos, Rafael Saldanha Dos; Dias, Fernando Suparregui; Dias, Alexandre Simões; Mestriner, Régis Gemerasca; Vieira, Silvia Regina Rios
2017-01-01
To evaluate the effects of bag-valve breathing maneuvers combined with standard manual chest compression techniques on safety, hemodynamics and oxygenation in stable septic shock patients. A parallel, assessor-blinded, randomized trial of two groups. A computer-generated list of random numbers was prepared by an independent researcher to allocate treatments. The Intensive Care Unit at Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul. Fifty-two subjects were assessed for eligibility, and 32 were included. All included subjects (n = 32) received the allocated intervention (n = 19 for the Experimental Group and n = 13 for the Control Group). Twenty minutes of bag-valve breathing maneuvers combined with manual chest compression techniques (Experimental Group) or chest compression, as routinely used at our intensive care unit (Control Group). Follow-up was performed immediately after and at 30 minutes after the intervention. Mean artery pressure. All included subjects completed the trial (N = 32). We found no relevant effects on mean artery pressure (p = 0.17), heart rate (p = 0.50) or mean pulmonary artery pressure (p = 0.89) after adjusting for subject age and weight. Both groups were identical regarding oxygen consumption after the data adjustment (p = 0.84). Peripheral oxygen saturation tended to increase over time in both groups (p = 0.05), and there was no significant association between cardiac output and venous oxygen saturation (p = 0.813). No clinical deterioration was observed. A single session of bag-valve breathing maneuvers combined with manual chest compression is hemodynamically safe for stable septic-shocked subjects over the short-term.
Rice, Anne M; Mahling, Ryan; Fealey, Michael E; Rannikko, Anika; Dunleavy, Katie; Hendrickson, Troy; Lohese, K Jean; Kruggel, Spencer; Heiling, Hillary; Harren, Daniel; Sutton, R Bryan; Pastor, John; Hinderliter, Anne
2014-09-01
Eukaryotic lipids in a bilayer are dominated by weak cooperative interactions. These interactions impart highly dynamic and pliable properties to the membrane. C2 domain-containing proteins in the membrane also interact weakly and cooperatively giving rise to a high degree of conformational plasticity. We propose that this feature of weak energetics and plasticity shared by lipids and C2 domain-containing proteins enhance a cell's ability to transduce information across the membrane. We explored this hypothesis using information theory to assess the information storage capacity of model and mast cell membranes, as well as differential scanning calorimetry, carboxyfluorescein release assays, and tryptophan fluorescence to assess protein and membrane stability. The distribution of lipids in mast cell membranes encoded 5.6-5.8bits of information. More information resided in the acyl chains than the head groups and in the inner leaflet of the plasma membrane than the outer leaflet. When the lipid composition and information content of model membranes were varied, the associated C2 domains underwent large changes in stability and denaturation profile. The C2 domain-containing proteins are therefore acutely sensitive to the composition and information content of their associated lipids. Together, these findings suggest that the maximum flow of signaling information through the membrane and into the cell is optimized by the cooperation of near-random distributions of membrane lipids and proteins. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova. Copyright © 2014 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Busch, Peter Andre; Zinner Henriksen, Helle
2018-01-01
discretion is suggested to reduce this footprint by influencing or replacing their discretionary practices using ICT. What is less researched is whether digital discretion can cause changes in public policy outcomes, and under what conditions such changes can occur. Using the concept of public service values......This study reviews 44 peer-reviewed articles on digital discretion published in the period from 1998 to January 2017. Street-level bureaucrats have traditionally had a wide ability to exercise discretion stirring debate since they can add their personal footprint on public policies. Digital......, we suggest that digital discretion can strengthen ethical and democratic values but weaken professional and relational values. Furthermore, we conclude that contextual factors such as considerations made by policy makers on the macro-level and the degree of professionalization of street...
Brémaud, Pierre
2017-01-01
The emphasis in this book is placed on general models (Markov chains, random fields, random graphs), universal methods (the probabilistic method, the coupling method, the Stein-Chen method, martingale methods, the method of types) and versatile tools (Chernoff's bound, Hoeffding's inequality, Holley's inequality) whose domain of application extends far beyond the present text. Although the examples treated in the book relate to the possible applications, in the communication and computing sciences, in operations research and in physics, this book is in the first instance concerned with theory. The level of the book is that of a beginning graduate course. It is self-contained, the prerequisites consisting merely of basic calculus (series) and basic linear algebra (matrices). The reader is not assumed to be trained in probability since the first chapters give in considerable detail the background necessary to understand the rest of the book. .
Giuliano, Rita; Szewczak, Zbigniew S.
2013-01-01
In the present paper we obtain a new correlation inequality and use it for the purpose of extending the theory of the Almost Sure Local Limit Theorem to the case of lattice random sequences in the domain of attraction of a stable law. In particular, we prove ASLLT in the case of the normal domain of attraction of $\\alpha$--stable law, $\\alpha\\in(1,2)$.
Stable and efficient retrospective 4D-MRI using non-uniformly distributed quasi-random numbers
Breuer, Kathrin; Meyer, Cord B.; Breuer, Felix A.; Richter, Anne; Exner, Florian; Weng, Andreas M.; Ströhle, Serge; Polat, Bülent; Jakob, Peter M.; Sauer, Otto A.; Flentje, Michael; Weick, Stefan
2018-04-01
The purpose of this work is the development of a robust and reliable three-dimensional (3D) Cartesian imaging technique for fast and flexible retrospective 4D abdominal MRI during free breathing. To this end, a non-uniform quasi random (NU-QR) reordering of the phase encoding (k y –k z ) lines was incorporated into 3D Cartesian acquisition. The proposed sampling scheme allocates more phase encoding points near the k-space origin while reducing the sampling density in the outer part of the k-space. Respiratory self-gating in combination with SPIRiT-reconstruction is used for the reconstruction of abdominal data sets in different respiratory phases (4D-MRI). Six volunteers and three patients were examined at 1.5 T during free breathing. Additionally, data sets with conventional two-dimensional (2D) linear and 2D quasi random phase encoding order were acquired for the volunteers for comparison. A quantitative evaluation of image quality versus scan times (from 70 s to 626 s) for the given sampling schemes was obtained by calculating the normalized mutual information (NMI) for all volunteers. Motion estimation was accomplished by calculating the maximum derivative of a signal intensity profile of a transition (e.g. tumor or diaphragm). The 2D non-uniform quasi-random distribution of phase encoding lines in Cartesian 3D MRI yields more efficient undersampling patterns for parallel imaging compared to conventional uniform quasi-random and linear sampling. Median NMI values of NU-QR sampling are the highest for all scan times. Therefore, within the same scan time 4D imaging could be performed with improved image quality. The proposed method allows for the reconstruction of motion artifact reduced 4D data sets with isotropic spatial resolution of 2.1 × 2.1 × 2.1 mm3 in a short scan time, e.g. 10 respiratory phases in only 3 min. Cranio-caudal tumor displacements between 23 and 46 mm could be observed. NU-QR sampling enables for stable 4D
Rights, Jason D; Sterba, Sonya K
2016-11-01
Multilevel data structures are common in the social sciences. Often, such nested data are analysed with multilevel models (MLMs) in which heterogeneity between clusters is modelled by continuously distributed random intercepts and/or slopes. Alternatively, the non-parametric multilevel regression mixture model (NPMM) can accommodate the same nested data structures through discrete latent class variation. The purpose of this article is to delineate analytic relationships between NPMM and MLM parameters that are useful for understanding the indirect interpretation of the NPMM as a non-parametric approximation of the MLM, with relaxed distributional assumptions. We define how seven standard and non-standard MLM specifications can be indirectly approximated by particular NPMM specifications. We provide formulas showing how the NPMM can serve as an approximation of the MLM in terms of intraclass correlation, random coefficient means and (co)variances, heteroscedasticity of residuals at level 1, and heteroscedasticity of residuals at level 2. Further, we discuss how these relationships can be useful in practice. The specific relationships are illustrated with simulated graphical demonstrations, and direct and indirect interpretations of NPMM classes are contrasted. We provide an R function to aid in implementing and visualizing an indirect interpretation of NPMM classes. An empirical example is presented and future directions are discussed. © 2016 The British Psychological Society.
Akkoç, Betül; Arslan, Ahmet; Kök, Hatice
2017-05-01
One of the first stages in the identification of an individual is gender determination. Through gender determination, the search spectrum can be reduced. In disasters such as accidents or fires, which can render identification somewhat difficult, durable teeth are an important source for identification. This study proposes a smart system that can automatically determine gender using 3D digital maxillary tooth plaster models. The study group was composed of 40 Turkish individuals (20 female, 20 male) between the ages of 21 and 24. Using the iterative closest point (ICP) algorithm, tooth models were aligned, and after the segmentation process, models were transformed into depth images. The local discrete cosine transform (DCT) was used in the process of feature extraction, and the random forest (RF) algorithm was used for the process of classification. Classification was performed using 30 different seeds for random generator values and 10-fold cross-validation. A value of 85.166% was obtained for average classification accuracy (CA) and a value of 91.75% for the area under the ROC curve (AUC). A multi-disciplinary study is performed here that includes computer sciences, medicine and dentistry. A smart system is proposed for the determination of gender from 3D digital models of maxillary tooth plaster models. This study has the capacity to extend the field of gender determination from teeth. Copyright © 2017 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Sørensen, John Aasted
2010-01-01
The introduction of the mathematics needed for analysis, design and verification of discrete systems, including applications within programming languages for computer systems. Course sessions and project work. Semester: Spring 2010 Ectent: 5 ects Class size: 18......The introduction of the mathematics needed for analysis, design and verification of discrete systems, including applications within programming languages for computer systems. Course sessions and project work. Semester: Spring 2010 Ectent: 5 ects Class size: 18...
DEFF Research Database (Denmark)
Sørensen, John Aasted
2010-01-01
The introduction of the mathematics needed for analysis, design and verification of discrete systems, including applications within programming languages for computer systems. Course sessions and project work. Semester: Autumn 2010 Ectent: 5 ects Class size: 15......The introduction of the mathematics needed for analysis, design and verification of discrete systems, including applications within programming languages for computer systems. Course sessions and project work. Semester: Autumn 2010 Ectent: 5 ects Class size: 15...
Vijayakumar, Maniyal; Vasudevan, D M; Sundaram, K R; Krishnan, Sajitha; Vaidyanathan, Kannan; Nandakumar, Sandya; Chandrasekhar, Rajiv; Mathew, Navin
2016-01-01
Coronary artery disease (CAD) and its pathological atherosclerotic process are closely related to lipids. Lipids levels are in turn influenced by dietary oils and fats. Saturated fatty acids increase the risk for atherosclerosis by increasing the cholesterol level. This study was conducted to investigate the impact of cooking oil media (coconut oil and sunflower oil) on lipid profile, antioxidant mechanism, and endothelial function in patients with established CAD. In a single center randomized study in India, patients with stable CAD on standard medical care were assigned to receive coconut oil (Group I) or sunflower oil (Group II) as cooking media for 2 years. Anthropometric measurements, serum, lipids, Lipoprotein a, apo B/A-1 ratio, antioxidants, flow-mediated vasodilation, and cardiovascular events were assessed at 3 months, 6 months, 1 year, and 2 years. Hundred patients in each arm completed 2 years with 98% follow-up. There was no statistically significant difference in the anthropometric, biochemical, vascular function, and in cardiovascular events after 2 years. Coconut oil even though rich in saturated fatty acids in comparison to sunflower oil when used as cooking oil media over a period of 2 years did not change the lipid-related cardiovascular risk factors and events in those receiving standard medical care. Copyright © 2015 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Augusto Hernández Vidal
2011-12-01
Full Text Available In order to strengthen the concept of municipal autonomy, this essay proposes an extensive interpretation of administrative discretion. Discretion is the exercise of free judgment given by law to authorities for performing official acts. This legislative technique seems to be suitable whenever the legislative is intended to legislate over the essential core of municipal autonomy. This way, an eventual abuse of that autonomy could be avoided, for the disproportional restriction of the local faculty to oversee the local issues. This alternative is presented as a tool to provide with dynamism the performing of administrative activities as well, aiming to assimilate public administration new practices.
DEFF Research Database (Denmark)
Sørensen, John Aasted
2011-01-01
The objectives of Discrete Mathematics (IDISM2) are: The introduction of the mathematics needed for analysis, design and verification of discrete systems, including the application within programming languages for computer systems. Having passed the IDISM2 course, the student will be able....... Having completed this the student is able to carry out the following: Expressions and sets: Define a set; define a logic expression; negate a logic expression; combine logic expressions; construct a truth table for a logic expression; apply reduction rules for logic expressions. Apply these concepts...
Caltagirone, Jean-Paul
2014-01-01
This book presents the fundamental principles of mechanics to re-establish the equations of Discrete Mechanics. It introduces physics and thermodynamics associated to the physical modeling. The development and the complementarity of sciences lead to review today the old concepts that were the basis for the development of continuum mechanics. The differential geometry is used to review the conservation laws of mechanics. For instance, this formalism requires a different location of vector and scalar quantities in space. The equations of Discrete Mechanics form a system of equations where the H
Granacher, Urs; Schellbach, Jörg; Klein, Katja; Prieske, Olaf; Baeyens, Jean-Pierre; Muehlbauer, Thomas
2014-01-01
It has been demonstrated that core strength training is an effective means to enhance trunk muscle strength (TMS) and proxies of physical fitness in youth. Of note, cross-sectional studies revealed that the inclusion of unstable elements in core strengthening exercises produced increases in trunk muscle activity and thus provide potential extra training stimuli for performance enhancement. Thus, utilizing unstable surfaces during core strength training may even produce larger performance gains. However, the effects of core strength training using unstable surfaces are unresolved in youth. This randomized controlled study specifically investigated the effects of core strength training performed on stable surfaces (CSTS) compared to unstable surfaces (CSTU) on physical fitness in school-aged children. Twenty-seven (14 girls, 13 boys) healthy subjects (mean age: 14 ± 1 years, age range: 13-15 years) were randomly assigned to a CSTS (n = 13) or a CSTU (n = 14) group. Both training programs lasted 6 weeks (2 sessions/week) and included frontal, dorsal, and lateral core exercises. During CSTU, these exercises were conducted on unstable surfaces (e.g., TOGU© DYNAIR CUSSIONS, THERA-BAND© STABILITY TRAINER). Significant main effects of Time (pre vs. post) were observed for the TMS tests (8-22%, f = 0.47-0.76), the jumping sideways test (4-5%, f = 1.07), and the Y balance test (2-3%, f = 0.46-0.49). Trends towards significance were found for the standing long jump test (1-3%, f = 0.39) and the stand-and-reach test (0-2%, f = 0.39). We could not detect any significant main effects of Group. Significant Time x Group interactions were detected for the stand-and-reach test in favour of the CSTU group (2%, f = 0.54). Core strength training resulted in significant increases in proxies of physical fitness in adolescents. However, CSTU as compared to CSTS had only limited additional effects (i.e., stand-and-reach test). Consequently, if the
Directory of Open Access Journals (Sweden)
Yuexiu Wu
2017-01-01
Full Text Available It is essential to study nuclide transport with underground water in fractured rock masses in order to evaluate potential radionuclide leakage in nuclear waste disposal. A time-domain random-walk (TDRW method was firstly implemented into a discrete element method (DEM, that is, UDEC, in this paper to address the pressing challenges of modelling the nuclide transport in fractured rock masses such as massive fractures and coupled hydromechanical effect. The implementation was then validated against analytical solutions for nuclide transport in a single fracture and a simple fracture network. After that, the proposed implementation was applied to model the nuclide transport in a complex fracture network investigated in the DECOVALEX 2011 project to analyze the effect of matrix diffusion and stress on the nuclide transport in the fractured rock masses. It was concluded that the implementation of the TDRW method into UDEC provided a valuable tool to study the nuclide transport in the fractured rock masses. Moreover, it was found that the total travel time of the nuclide particles in the fractured rock masses with the matrix diffusion and external stress modelled was much longer than that without the matrix diffusion and external stress modelled.
International Nuclear Information System (INIS)
Sharpe, Eric
2003-01-01
In this article we explain discrete torsion. Put simply, discrete torsion is the choice of orbifold group action on the B field. We derive the classification H 2 (Γ,U(1)), the twisted sector phases appearing in string loop partition functions, Douglas's description of discrete torsion for D-branes in terms of a projective representation of the orbifold group, and outline how the results of Vafa and Witten fit into this framework. In addition, we observe that additional degrees of freedom (known as shift orbifolds) appear in describing orbifold group actions on B fields, in addition to those classified by H 2 (Γ,U(1)), and explain how these degrees of freedom appear in terms of twisted sector contributions to partition functions and in terms of orbifold actions on D-brane worldvolumes. This paper represents a technically simplified version of prior papers by the author on discrete torsion. We repeat here technically simplified versions of results from those papers, and have included some new material
DEFF Research Database (Denmark)
Roager, Henrik Munch; Licht, Tine Rask; Poulsen, Sanne
2014-01-01
It has been suggested that the human gut microbiota can be divided into enterotypes based on the abundance of specific bacterial groups; however, the biological significance and stability of these enterotypes remain unresolved. Here, we demonstrated that subjects (n = 62) 18 to 65 years old...... with central obesity and components of metabolic syndrome could be grouped into two discrete groups simply by their relative abundance of Prevotella spp. divided by Bacteroides spp. (P/B ratio) obtained by quantitative PCR analysis. Furthermore, we showed that these groups remained stable during a 6-month......, controlled dietary intervention, where the effect of consuming a diet in accord with the new Nordic diet (NND) recommendations as opposed to consuming the average Danish diet (ADD) on the gut microbiota was investigated. In this study, subjects (with and without stratification according to P/B ratio) did...
SOME LIMIT THEORY FOR THE SELF-NORMALIZED PERIODOGRAM OF STABLE PROCESSES
KLUPPELBERG, C; MIKOSCH, T
1994-01-01
Let X(t) = Sigma(j)(infinity) = (-infinity) psi(j)Z(t-j) be a discrete moving average process based on i.i.d. random variables (Z(t),)(t epsilon Z) with common distribution function from the domain of normal attraction of a p-stable law (0
Parker, R Gary
1988-01-01
This book treats the fundamental issues and algorithmic strategies emerging as the core of the discipline of discrete optimization in a comprehensive and rigorous fashion. Following an introductory chapter on computational complexity, the basic algorithmic results for the two major models of polynomial algorithms are introduced--models using matroids and linear programming. Further chapters treat the major non-polynomial algorithms: branch-and-bound and cutting planes. The text concludes with a chapter on heuristic algorithms.Several appendixes are included which review the fundamental ideas o
Vonkeman, Harald Erwin; Moghadam, M.G.; van de Laar, Mart A F J; ten Klooster, Peter M.; Jansen, T.; van Riel, P.
2014-01-01
Background/Purpose: The effectiveness of TNF-inhibitors (TNFi) in the treatment of rheumatoid arthritis has already been demonstrated in many studies. However, little is known on stopping TNFi in patients with stable low disease activity and the subsequent likelihood of exacerbation of rheumatoid
Nachman, SA; Stanley, K; Yogev, R; Pelton, S; Wiznia, A; Lee, S; Mofenson, L; Fiscus, S; Rathore, M; Jimenez, E; Borkowsky, W; Pitt, J; Smith, ME; Wells, B; McIntosh, K
2000-01-01
Context Although protease inhibitors are used routinely in adults with human immunodeficiency virus (HIV) infection, the role of these drugs in the treatment of clinically stable HIV-infected children is not clear. Objective To evaluate the safety, tolerance, and virologic response produced by a
Liu, Miao; Zheng, Fengjie; Ni, Lei; Sun, Yan; Wu, Ruohan; Zhang, Tianyu; Zhang, Jinchao; Zhong, Xianggen; Li, Yuhang
2016-08-01
To evaluate the efficacy and safety of sugarcane bagasse dietary fiber as an adjuvant therapy for improving quality of life in patients with stable chronic obstructive pulmonary disease (COPD). This was a multicenter, randomized, double-blind, placebo-controlled trial. A total of 196 participants were randomized into a trial group (treated with 6 g/day sugarcane bagasse plus conventional treatment, n = 98) and a control group (treated with placebo plus conventional treatment, n = 98). All efficacy analyses were performed according to the intention-to-treat (ITT) principle. A per-protocol analysis set (PPS) was used to analyze the cases that completed the clinical trial with good compliance. The trial period was 30 days, with a 6-month follow-up. Pre- and post-treatment pulmonary symptom scores (cough, sputum, wheezing, and dyspnea) were recorded for both groups. The St. George's Respiratory Questionnaire (SGRQ) and the modified Medical Research Council (mMRC) dyspnea scale were assessed before treatment and at the end of the 6-month follow- up. The ITT population was 178 and the PPS population was 166. Post-treatment pulmonary clinical symptoms and severity of dyspnea (mMRC and SGRQ evaluation) were significantly improved in both the trial group and the control group (ITT and PPS: P Sugarcane bagasse combined with conventional treatment improved quality of life in patients with stable COPD. Sugarcane bagasse appears to be a safe herbal medicine with potential for treating patients with stable COPD when taken orally as an adjuvant therapy.
Firth, Jean M
1992-01-01
The analysis of signals and systems using transform methods is a very important aspect of the examination of processes and problems in an increasingly wide range of applications. Whereas the initial impetus in the development of methods appropriate for handling discrete sets of data occurred mainly in an electrical engineering context (for example in the design of digital filters), the same techniques are in use in such disciplines as cardiology, optics, speech analysis and management, as well as in other branches of science and engineering. This text is aimed at a readership whose mathematical background includes some acquaintance with complex numbers, linear differen tial equations, matrix algebra, and series. Specifically, a familiarity with Fourier series (in trigonometric and exponential forms) is assumed, and an exposure to the concept of a continuous integral transform is desirable. Such a background can be expected, for example, on completion of the first year of a science or engineering degree cour...
Discrete dynamics of complex systems
Directory of Open Access Journals (Sweden)
Hermann Haken
1997-01-01
Full Text Available This article extends the slaving principle of synergetics to processes with discrete time steps. Starting point is a set of nonlinear difference equations which contain multiplicative noise and which refer to multidimensional state vectors. The system depends on a control parameter. When its value is changed beyond a critical value, an instability of the solution occurs. The stability analysis allows us to divide the system into stable and unstable modes. The original equations can be transformed to a set of difference equations for the unstable and stable modes. The extension of the slaving principle to the time-discrete case then states that all the stable modes can be explicitly expressed by the unstable modes or so-called order-parameters.
Wuensche, Andrew
DDLab is interactive graphics software for creating, visualizing, and analyzing many aspects of Cellular Automata, Random Boolean Networks, and Discrete Dynamical Networks in general and studying their behavior, both from the time-series perspective — space-time patterns, and from the state-space perspective — attractor basins. DDLab is relevant to research, applications, and education in the fields of complexity, self-organization, emergent phenomena, chaos, collision-based computing, neural networks, content addressable memory, genetic regulatory networks, dynamical encryption, generative art and music, and the study of the abstract mathematical/physical/dynamical phenomena in their own right.
Schwarz, Konstantin; Singh, Satnam; Parasuraman, Satish Kumar; Bruce, Maggie; Shepstone, Lee; Feelisch, Martin; Minnion, Magdalena; Ahmad, Shakil; Horowitz, John; Dawson, Dana K; Frenneaux, Michael P
2016-11-01
In an aging western population, a significant number of patients continue to suffer from angina once all revascularization and optimal medical treatment options are exhausted. Under experimental conditions, oral supplementation with inorganic nitrate was shown to exhibit a blood pressure-lowering effect, and has also been shown to promote angiogenesis, improve endothelial dysfunction and mitochondrial efficiency in skeletal muscle. It is unknown whether similar changes occur in cardiac muscle. In the current study, we investigate whether oral sodium nitrate treatment will improve myocardial ischemia in patients with stable angina.
Dimension Reduction and Discretization in Stochastic Problems by Regression Method
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager
1996-01-01
The chapter mainly deals with dimension reduction and field discretizations based directly on the concept of linear regression. Several examples of interesting applications in stochastic mechanics are also given.Keywords: Random fields discretization, Linear regression, Stochastic interpolation...
Discrete Choice and Rational Inattention
DEFF Research Database (Denmark)
Fosgerau, Mogens; Melo, Emerson; de Palma, André
2017-01-01
This paper establishes a general equivalence between discrete choice and rational inattention models. Matejka and McKay (2015, AER) showed that when information costs are modelled using the Shannon entropy, the result- ing choice probabilities in the rational inattention model take the multinomial...... logit form. We show that when information costs are modelled using a class of generalized entropies, then the choice probabilities in any rational inattention model are observationally equivalent to some additive random utility discrete choice model and vice versa. This equivalence arises from convex......- analytic properties of the random utility model. Thus any additive random utility model can be given an interpretation in terms of boundedly rational behavior. We provide examples of this equivalence utilizing the nested logit model, an empirically relevant random utility model allowing for flexible...
Directory of Open Access Journals (Sweden)
Przemyslaw Kardas
2007-05-01
Full Text Available Przemyslaw KardasThe First Department of Family Medicine, Medical University of LodzBackground: A randomized, controlled trial was conducted in an outpatient setting to examine the effect of beta-blocker dosing frequency on patient compliance, clinical outcome, and health-related quality of life in patients with stable angina pectoris.Methods: One hundred and twelve beta-blockers-naive outpatients with stable angina pectoris were randomized to receive betaxolol, 20 mg once daily or metoprolol tartrate, 50 mg twice daily for 8 weeks. The principal outcome measure was overall compliance measured electronically, whereas secondary outcome measures were drug effectiveness and health-related quality of life.Results: The overall compliance was 86.5 ± 21.3% in the betaxolol group versus 76.1 ± 26.3% in the metoprolol group (p < 0.01, and the correct number of doses was taken on 84.4 ± 21.6% and 64.0 ± 31.7% of treatment days, respectively (p < 0.0001. The percentage of missed doses was 14.5 ± 21.5% in the once-daily group and 24.8 ± 26.4% in the twice-daily group (p < 0.01. The percentage of doses taken in the correct time window (58.6% vs 42.0%, p = 0.01, correct interdose intervals (77.4% v 53.1%, p < 0.0001, and therapeutic coverage (85.6% vs 73.7%, p < 0.001 were significantly higher in the once-daily group. Both studied drugs had similar antianginal effectiveness. Health-related quality of life improved in both groups, but this increase was more pronounced in the betaxolol arm in some dimensions.Conclusions: The study demonstrates that patient compliance with once-daily betaxolol is significantly better than with twice daily metoprolol. Similarly, this treatment provides better quality of life. These results demonstrate possible therapeutic advantages of once-daily over twice-daily beta-blockers in the treatment of stable angina pectoris.Keywords: patient compliance, quality of life, stable angina pectoris, randomized controlled trial
The remarkable discreteness of being
Indian Academy of Sciences (India)
2014-03-15
Mar 15, 2014 ... atomistic theory and give a simple, elegant explanation to all these laws. Around 1900 AD, Planck, ... In none of the cases reviewed here is it claimed that a simple discrete theory will explain all the phenomena. ..... of migration a decreasing function of the distance; (iii) due to random sampling from one ...
The remarkable discreteness of being
Indian Academy of Sciences (India)
Life is a discrete, stochastic phenomenon: for a biological organism, the time of the two most important events of its life (reproduction and death) is random and these events change the number of individuals of the species by single units. These facts can have surprising, counterintuitive consequences. I review here three ...
Low-lying dipole response in the stable 40,48Ca nuclei within the second random-phase approximation
International Nuclear Information System (INIS)
Gambacurta, D.; Grasso, M.; Catara, F.
2012-01-01
The low-lying dipole strength distributions of 40 CaCa and 48 Ca, in the energy region between 5 and 10 MeV, are studied within the second random phase approximation (RPA) with Skyrme interaction. Standard RPA models do not usually predict any presence of strength in this energy region, while experimentally a significant amount of strength is found. The inclusion of the 2 particle −2 hole configurations allows to obtain a description in a rather good agreement with the experimental data. The properties of the most collective state are analyzed in terms of its 1 particle −1 hole nature and its transition densities.
Low-lying dipole response in the stable 40,48Ca nuclei within the second random-phase approximation
Gambacurta, D.; Grasso, M.; Catara, F.
2012-10-01
The low-lying dipole strength distributions of 40CaCa and 48Ca, in the energy region between 5 and 10 MeV, are studied within the second random phase approximation (RPA) with Skyrme interaction. Standard RPA models do not usually predict any presence of strength in this energy region, while experimentally a significant amount of strength is found. The inclusion of the 2 particle -2 hole configurations allows to obtain a description in a rather good agreement with the experimental data. The properties of the most collective state are analyzed in terms of its 1 particle -1 hole nature and its transition densities.
Liu, Xin; Zhang, Hui; Feng, Hua; Hong, Lei; Wang, Xue-Song; Song, Guan-Yang
2017-04-01
A special type of meniscal lesion involving the peripheral attachment of the posterior horn of the medial meniscus (PHMM), termed a "ramp lesion," is commonly associated with an anterior cruciate ligament (ACL) injury. However, its treatment is still controversial. Recently, stable ramp lesions treated with abrasion and trephination alone have been shown to have good clinical outcomes after ACL reconstruction. Stable ramp lesions treated with abrasion and trephination alone during ACL reconstruction will result in similar clinical outcomes compared with those treated with surgical repair. Randomized controlled trial; Level of evidence, 2. A prospective randomized controlled study was performed in 91 consecutive patients who had complete ACL injuries and concomitant stable ramp lesions of the medial meniscus. All patients were randomly allocated to 1 of 2 groups based on whether the stable ramp lesions were surgically repaired (study group; n = 50) or only abraded and trephined (control group; n = 41) during ACL reconstruction. All surgical procedures were performed by a single surgeon who was blinded to the functional assessment findings of the patients. The Lysholm score, subjective International Knee Documentation Committee (IKDC) score, and stability assessments (pivot-shift test, Lachman test, KT-1000 arthrometer side-to-side difference, and KT-1000 arthrometer differences of 5 mm) were evaluated preoperatively and at the last follow-up. Moreover, magnetic resonance imaging (MRI) was used to evaluate the healing status of the ramp lesions. All consecutive patients who were screened for eligibility from August 2008 to April 2012 were enrolled and observed clinically. There were 40 patients in the study group and 33 patients in the control group who were observed for at least 2 years. At the final follow-up, there were no significant differences between the study group and the control group in terms of the mean Lysholm score (88.7 ± 4.8 vs 90.4 ± 5
Discrete Curvatures and Discrete Minimal Surfaces
Sun, Xiang
2012-06-01
This thesis presents an overview of some approaches to compute Gaussian and mean curvature on discrete surfaces and discusses discrete minimal surfaces. The variety of applications of differential geometry in visualization and shape design leads to great interest in studying discrete surfaces. With the rich smooth surface theory in hand, one would hope that this elegant theory can still be applied to the discrete counter part. Such a generalization, however, is not always successful. While discrete surfaces have the advantage of being finite dimensional, thus easier to treat, their geometric properties such as curvatures are not well defined in the classical sense. Furthermore, the powerful calculus tool can hardly be applied. The methods in this thesis, including angular defect formula, cotangent formula, parallel meshes, relative geometry etc. are approaches based on offset meshes or generalized offset meshes. As an important application, we discuss discrete minimal surfaces and discrete Koenigs meshes.
Directory of Open Access Journals (Sweden)
Nevio Taglieri
Full Text Available Stroke is a rare but serious adverse event associated with percutaneous coronary intervention (PCI. However, the relative risk of stroke between stable patients undergoing a direct PCI strategy and those undergoing an initial optimal medical therapy (OMT strategy has not been established yet. This study sought to investigate if, in patients with stable coronary artery disease (SCAD, an initial strategy PCI is associated with a higher risk of stroke than a strategy based on OMT alone.We performed a meta-analysis of 6 contemporary randomized control trials in which 5673 patients with SCAD were randomized to initial PCI or OMT. Only trials with stent utilization more than 50% were included. Study endpoint was the rate of stroke during follow up.Mean age of patients ranged from 60 to 65 years and stent utilization ranged from 72% to 100%. Rate of stroke was 2.0% at a weighted mean follow up of 55.3 months. On pooled analysis, the risk of stroke was similar between patients undergoing a PCI plus OMT and those receiving only OMT (2.2% vs. 1.8%, OR on fixed effect = 1.24 95%CI: 0.85-1.79. There was no heterogeneity among the studies (I2 = 0.0%, P = 0.15. On sensitivity analysis after removing each individual study the pooled effect estimate remains unchanged.In patients with SCAD an initial strategy based on a direct PCI is not associated with an increased risk of stroke during long-term follow up compared to an initial strategy based on OMT alone.
Xu, Yuan-hong; Wang, Jun-hua; Li, Hai-feng; Zhu, Xiao-hu; Wang, Gang
2010-05-01
Chronic obstructive pulmonary disease (COPD) is an important clinical disease, and its global prevalence and mortality rates are high. It is meaningful to investigate the efficacy of integrative respiratory rehabilitation training in quality of life and respiratory physiology of COPD patients in stable phase. To observe the efficacy of integrative respiratory rehabilitation training in exercise ability and quality of life of COPD patients in stable phase. Eighty outpatients and inpatients with COPD from Department of Respiratory Medicine, Taihe Hospital, Yunyang Medical College were randomly divided into 4 groups, with 20 patients in each group. The patients in group A only received drug therapy, the patients in group B received traditional qigong training, the patients in group C received modern rehabilitation training, and the patients in group D received integrative respiratory rehabilitation training. Chronic respiratory questionnaire (CRQ), 6-minute walking distance and Borg score in each group were examined before and after one-, three-, and six-month and one-year treatment. The 6-minute walking distance, Borg score and CRQ score in group A had no significant changes after treatment (P>0.05). After one-month treatment, there were no significant differences in 6-minute walking distance and Borg score in groups B, C and D as compared with those before treatment (Pexercise ability of COPD patients, and integrative respiratory rehabilitation training program is better than modern rehabilitation training and traditional qigong training programs. The efficacy of respiratory rehabilitation training is time-dependent, and need long-time adherence to the therapy.
Widmer, Mariana; Piaggio, Gilda; Abdel-Aleem, Hany; Carroli, Guillermo; Chong, Yap-Seng; Coomarasamy, Arri; Fawole, Bukola; Goudar, Shivaprasad; Hofmeyr, G Justus; Lumbiganon, Pisake; Mugerwa, Kidza; Nguyen, Thi My Huong; Qureshi, Zahida; Souza, Joao Paulo; Gülmezoglu, A Metin
2016-03-17
Postpartum haemorrhage (PPH) is the leading cause of maternal mortality in low-income countries and contributes to nearly a quarter of maternal deaths globally. The current available interventions for prevention of postpartum haemorrhage, oxytocin and carbetocin, are limited by their need for refrigeration to maintain potency, as the ability to maintain a cold chain across the drug distribution and storage network is inconsistent, thus restricting their use in countries with the highest burden of maternal mortality. We describe a randomized, double-blind non-inferiority trial comparing a newly developed room temperature stable formulation of carbetocin to the standard intervention (oxytocin) for the prevention of PPH after vaginal birth. Approximately 30,000 women delivering vaginally will be recruited across 22 centres in 10 countries. The primary objectives are to evaluate the non-inferiority of room temperature stable carbetocin (100 μg intramuscular) versus oxytocin (10 IU intramuscular) in the prevention of PPH and severe PPH after vaginal birth. The primary endpoints are blood loss ≥500 mL or the use of additional uterotonics (composite endpoint required by drug regulatory authorities) and blood loss ≥1,000 mL (WHO requirement). Non-inferiority will be assessed using a two-sided 95 % confidence interval for the relative risk of the above endpoints for room temperature stable carbetocin versus oxytocin. The upper limit of the two-sided 95 % confidence interval for the relative risk for the composite endpoint of blood loss ≥500 mL or the use of additional uterotonics, and for the endpoint of blood loss ≥1,000 mL, will be compared to a non-inferiority margin of 1.16 and 1.23, respectively. If the upper limit is below the corresponding margin, non-inferiority will have been demonstrated. The safety analysis will include all women receiving treatment. Safety and tolerability will be assessed by a review of adverse events, by conducting inferential testing
Groupoids, Discrete Mechanics, and Discrete Variation
International Nuclear Information System (INIS)
Guo Jiafeng; Jia Xiaoyu; Wu Ke; Zhao Weizhong
2008-01-01
After introducing some of the basic definitions and results from the theory of groupoid and Lie algebroid, we investigate the discrete Lagrangian mechanics from the viewpoint of groupoid theory and give the connection between groupoids variation and the methods of the first and second discrete variational principles
Meirovitch, H; Koerber, S C; Rivier, J E; Hagler, A T
1994-07-01
The Helmholtz free energy F (rather than the energy) is the correct criterion for stability; therefore, calculation of F is important for peptides and proteins that can populate a large number of metastable states. The local states (LS) method proposed by H. Meirovitch [(1977) Chemical Physics Letters, Vol. 45, p. 389] enables one to obtain upper and lower bounds of the conformational free energy, FB (b,l) and FA (b,l), respectively, from molecular dynamics (MD) or Monte Carlo samples. The correlation parameter b is the number of consecutive dihedral or valence angles along the chain that are taken into account explicitly. The continuum angles are approximated by a discretization parameter l; the larger are b and l, the better the approximations; while FA can be estimated efficiently, it is more difficult to estimate FB. The method is further developed here by applying it to MD trajectories of a relatively large molecule (188 atoms), the potent "Asp4-Dpr10" antagonist [cyclo(4/10)-(Ac-delta 3Pro1-D-pFPhe2-D-Trp3-Asp4-Tyr5-D-Nal6-Leu7-Arg8 -Pro9- Dpr10-NH2)] of gonadotropin releasing hormone (GnRH). The molecule was simulated in vacuo at T = 300 K in two conformational states, previously investigated [J. Rizo et al. Journal of the American Chemical Society, (1992) Vol. 114, p. 2860], which differ by the orientation of the N-terminal tail, above (tail up, TU) and below (tail down, TD) the cyclic heptapeptide ring. As in previous applications of the LS method, we have found the following: (1) While FA is a crude approximation for the correct F, results for the difference, delta FA = FA (TD)-FA (TU) converge rapidly to 5.6 (1) kcal/mole as the approximation is improved (i.e., as b and l are increased), which suggests that this is the correct value for delta F; therefore TD is more stable than TU. (The corresponding difference in entropy, T delta SA = 1.3(2) kcal/mole, is equal to the value obtained by the harmonic approximation.) (2) The lowest approximation, which has
Projected discrete ordinates methods for numerical transport problems
Energy Technology Data Exchange (ETDEWEB)
Larsen, E.W.
1985-01-01
A class of Projected Discrete-Ordinates (PDO) methods is described for obtaining iterative solutions of discrete-ordinates problems with convergence rates comparable to those observed using Diffusion Synthetic Acceleration (DSA). The spatially discretized PDO solutions are generally not equal to the DSA solutions, but unlike DSA, which requires great care in the use of spatial discretizations to preserve stability, the PDO solutions remain stable and rapidly convergent with essentially arbitrary spatial discretizations. Numerical results are presented which illustrate the rapid convergence and the accuracy of solutions obtained using PDO methods with commonplace differencing methods.
Leong, Paul; Basham, Jane E; Yong, Theresa; Chazan, Adrian; Finlay, Paul; Barnes, Sara; Bardin, Phillip G; Campbell, Donald
2015-05-02
Dietary nitrate supplementation has been shown to decrease the oxygen cost of exercise and prolong exercise tolerance, as measured by sub-maximal exercise endurance distance and time at 85% V̇O2max, in both elite athletes and normal healthy subjects. Patients with chronic obstructive pulmonary disease (COPD) have reduced quality of life and ability to perform activities of daily living attributable to diminished exercise tolerance, and dietary nitrate may be able to ameliorate this. We performed a double-blind, computer-randomized placebo control crossover trial at a tertiary Australian hospital to investigate whether dietary nitrate supplementation as beetroot juice (BR) would augment submaximal exercise endurance in individuals with spirometrically confirmed stable moderate COPD. Volunteers underwent an incremental shuttle walk test to determine V̇O2max followed by a test dose of BR to establish safety in the study population. Participants performed an endurance shuttle walk test (ESWT) at 85% V̇O2max after randomization to either a 3 day wash-in of BR (4.8 mmol twice a day) or placebo (nitrate deplete BR), with a final dose on the morning of testing. They then crossed over after 4 day washout. Repeated measures two sided paired t-tests were employed. 35 participants were recruited with 19 completing the trial. In the initial safety phase, we measured systolic blood pressure over four hours post first dose of BR, and found a mean 10 mmHg decrement maximal at 1 hour. One individual developed symptomatic postural hypotension and was excluded. The primary outcomes of ESWT distance and time to fatigue improved by 11% and 6% respectively; however these differences did not achieve statistical significance (p = 0.494 and 0.693 respectively). Our study does not support a role for routine dietary nitrate supplementation for enhancement of exercise endurance in COPD. Australia and New Zealand Clinical Trial Register: ACTRN12611001088932.
Shaw, Leslee J; Weintraub, William S; Maron, David J; Hartigan, Pamela M; Hachamovitch, Rory; Min, James K; Dada, Marcin; Mancini, G B John; Hayes, Sean W; O'Rourke, Robert A; Spertus, John A; Kostuk, William; Gosselin, Gilbert; Chaitman, Bernard R; Knudtson, Merill; Friedman, John; Slomka, Piotr; Germano, Guido; Bates, Eric R; Teo, Koon K; Boden, William E; Berman, Daniel S
2012-08-01
The COURAGE trial reported similar clinical outcomes for patients with stable ischemic heart disease (SIHD) receiving optimal medical therapy (OMT) with or without percutaneous coronary intervention (PCI). The current post hoc substudy analysis examined the relationship between baseline stress myocardial ischemia and clinical outcomes based on randomized treatment assignment. A total of 1,381 randomized patients (OMT n = 699, PCI + OMT n = 682) underwent baseline stress myocardial perfusion single-photon emission computed tomographic imaging. Site investigators interpreted the extent of ischemia by the number of ischemic segments using a 6-segment myocardial model. Patients were divided into those with no to mild (ischemic segments) and moderate to severe ischemia (≥ 3 ischemic segments). Cox proportional hazards models were calculated to assess time to the primary end point of death or myocardial infarction. At baseline, moderate to severe ischemia occurred in more than one-quarter of patients (n = 468), and the incidence was comparable in both treatment groups (P = .36). The primary end point, death or myocardial infarction, was similar in the OMT and PCI + OMT treatment groups for no to mild (18% and 19%, P = .92) and moderate to severe ischemia (19% and 22%, P = .53, interaction P value = .65). There was no gradient increase in events for the overall cohort with the extent of ischemia. From the COURAGE trial post hoc substudy, the extent of site-defined ischemia did not predict adverse events and did not alter treatment effectiveness. Currently, evidence supports equipoise as to whether the extent and severity of ischemia impact on therapeutic effectiveness. Copyright © 2012 Mosby, Inc. All rights reserved.
Tiwari, Vijay K; Rawat, Nidhi; Neelam, Kumari; Kumar, Sundip; Randhawa, Gursharn S; Dhaliwal, Harcharan S
2010-12-01
Synthetic amphiploids are the immortal sources for studies on crop evolution, genome dissection, and introgression of useful variability from related species. Cytological analysis of synthetic decaploid wheat (Triticum aestivum L.) - Aegilops kotschyi Boiss. amphiploids (AABBDDUkUkSkSk) showed some univalents from the C1 generation onward followed by chromosome elimination. Most of the univalents came to metaphase I plate after the reductional division of paired chromosomes and underwent equational division leading to their elimination through laggards and micronuclei. Substantial variation in the chromosome number of pollen mother cells from different tillers, spikelets, and anthers of some plants also indicated somatic chromosome elimination. Genomic in situ hybridization, fluorescence in situ hybridization, and simple sequence repeat markers analysis of two amphiploids with reduced chromosomes indicated random chromosome elimination of various genomes with higher sensitivity of D followed by the Sk and Uk genomes to elimination, whereas 1D chromosome was preferentially eliminated in both the amphiploids investigated. One of the partial amphiploids, C4 T. aestivum 'Chinese Spring' - Ae. kotschyi 396 (2n = 58), with 34 T. aestivum, 14 Uk, and 10 Sk had stable meiosis and high fertility. The partial amphiploids with white glumes, bold seeds, and tough rachis with high grain macro- and micronutrients and resistance to powdery mildew could be used for T. aestivum biofortification and transfer of powdery mildew resistance.
ON DISTRIBUTIONS OF ORDER STATISTICS FROM NONIDENTICAL DISCRETE VARIABLES
Directory of Open Access Journals (Sweden)
Mehmet GÜNGÖR
2011-04-01
Full Text Available In this study, the distributions of X_r:n order statistic of innid discrete random variables are obtained.In addition, the distributions are also expressed in the form of an integral. Then, the results related to pf and dfof minimum and maximum order statistics of innid discrete random variables are given.
Application of an efficient Bayesian discretization method to biomedical data
Directory of Open Access Journals (Sweden)
Gopalakrishnan Vanathi
2011-07-01
Full Text Available Abstract Background Several data mining methods require data that are discrete, and other methods often perform better with discrete data. We introduce an efficient Bayesian discretization (EBD method for optimal discretization of variables that runs efficiently on high-dimensional biomedical datasets. The EBD method consists of two components, namely, a Bayesian score to evaluate discretizations and a dynamic programming search procedure to efficiently search the space of possible discretizations. We compared the performance of EBD to Fayyad and Irani's (FI discretization method, which is commonly used for discretization. Results On 24 biomedical datasets obtained from high-throughput transcriptomic and proteomic studies, the classification performances of the C4.5 classifier and the naïve Bayes classifier were statistically significantly better when the predictor variables were discretized using EBD over FI. EBD was statistically significantly more stable to the variability of the datasets than FI. However, EBD was less robust, though not statistically significantly so, than FI and produced slightly more complex discretizations than FI. Conclusions On a range of biomedical datasets, a Bayesian discretization method (EBD yielded better classification performance and stability but was less robust than the widely used FI discretization method. The EBD discretization method is easy to implement, permits the incorporation of prior knowledge and belief, and is sufficiently fast for application to high-dimensional data.
Siri, Benoît; Berry, Hugues; Cessac, Bruno; Delord, Bruno; Quoy, Mathias
2008-12-01
We present a mathematical analysis of the effects of Hebbian learning in random recurrent neural networks, with a generic Hebbian learning rule, including passive forgetting and different timescales, for neuronal activity and learning dynamics. Previous numerical work has reported that Hebbian learning drives the system from chaos to a steady state through a sequence of bifurcations. Here, we interpret these results mathematically and show that these effects, involving a complex coupling between neuronal dynamics and synaptic graph structure, can be analyzed using Jacobian matrices, which introduce both a structural and a dynamical point of view on neural network evolution. Furthermore, we show that sensitivity to a learned pattern is maximal when the largest Lyapunov exponent is close to 0. We discuss how neural networks may take advantage of this regime of high functional interest.
Finite Mathematics and Discrete Mathematics: Is There a Difference?
Johnson, Marvin L.
Discrete mathematics and finite mathematics differ in a number of ways. First, finite mathematics has a longer history and is therefore more stable in terms of course content. Finite mathematics courses emphasize certain particular mathematical tools which are useful in solving the problems of business and the social sciences. Discrete mathematics…
International Nuclear Information System (INIS)
Liang, C.S.; Coplin, B.; Wellington, K.
1985-01-01
Using a double-blind, crossover design, the comparative efficacy and safety of nifedipine and isosorbide dinitrate in the treatment of stable angina were studied in 34 patients. The study included a 2-week placebo washout period and two 6-week periods during which patients were randomized to either nifedipine or isosorbide dinitrate. The doses were titrated for each patient, and mean doses of the 2 drugs were comparable. A time-limited thallium treadmill test was performed at the end of each phase. Ischemic zone count rates were normalized to those of the nonischemic zone, and the change in this ratio with redistribution was calculated as reversible thallium defect. Two patients were discontinued from the study within 1 week after initiation of isosorbide dinitrate because of severe, intolerable headache. Two patients were withdrawn while receiving nifedipine: one had new congestive heart failure and the other had increasing angina. Of the remaining 30 patients who tolerated both drugs for at least 1 week, 4 patients from the isosorbide dinitrate group were either prematurely crossed over or discontinued from the study because of headache. One patient suffered headache from both drugs and was discontinued from the study. In the 30 patients, only nifedipine significantly reduced resting arterial pressure compared with baseline. Further, only nifedipine therapy resulted in significant decreases in the rate-pressure product and systolic pressure at a given workload. However, significant decreases in angina frequency, nitroglycerin consumption and exercise-induced maximum ST-segment depression and reversible thallium perfusion defect were produced by both nifedipine and isosorbide dinitrate
Deep Discrete Supervised Hashing
Jiang, Qing-Yuan; Cui, Xue; Li, Wu-Jun
2017-01-01
Hashing has been widely used for large-scale search due to its low storage cost and fast query speed. By using supervised information, supervised hashing can significantly outperform unsupervised hashing. Recently, discrete supervised hashing and deep hashing are two representative progresses in supervised hashing. On one hand, hashing is essentially a discrete optimization problem. Hence, utilizing supervised information to directly guide discrete (binary) coding procedure can avoid sub-opti...
Random eigenvalue problems revisited
Indian Academy of Sciences (India)
a stochastic reduced basis approximation which can be applied to discrete or discretized continuous dynamic systems. ... methods are proposed to obtain joint distributions of the natural frequencies of discrete linear systems. In § 2, some ... variables are Gaussian. When the basic random variables are non-Gaussian, a new.
International Nuclear Information System (INIS)
Evans, D.K.
1986-01-01
Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)
Okuyama, Yoshifumi
2014-01-01
Discrete Control Systems establishes a basis for the analysis and design of discretized/quantized control systemsfor continuous physical systems. Beginning with the necessary mathematical foundations and system-model descriptions, the text moves on to derive a robust stability condition. To keep a practical perspective on the uncertain physical systems considered, most of the methods treated are carried out in the frequency domain. As part of the design procedure, modified Nyquist–Hall and Nichols diagrams are presented and discretized proportional–integral–derivative control schemes are reconsidered. Schemes for model-reference feedback and discrete-type observers are proposed. Although single-loop feedback systems form the core of the text, some consideration is given to multiple loops and nonlinearities. The robust control performance and stability of interval systems (with multiple uncertainties) are outlined. Finally, the monograph describes the relationship between feedback-control and discrete ev...
Dynamical attraction to stable processes
Fisher, Albert M.; Talet, Marina
2012-01-01
We apply dynamical ideas within probability theory, proving an almost-sure invariance principle in log density for stable processes. The familiar scaling property (self-similarity) of the stable process has a stronger expression, that the scaling flow on Skorokhod path space is a Bernoulli flow. We prove that typical paths of a random walk with i.i.d. increments in the domain of attraction of a stable law can be paired with paths of a stable process so that, after applying a non-random regula...
Zhang, Jing; Song, Yuan-Lin; Bai, Chun-Xue
2013-01-01
Chronic obstructive pulmonary disease (COPD) is a common disease that leads to huge economic and social burden. Efficient and effective management of stable COPD is essential to improve quality of life and reduce medical expenditure. The Internet of Things (IoT), a recent breakthrough in communication technology, seems promising in improving health care delivery, but its potential strengths in COPD management remain poorly understood. We have developed a mobile phone-based IoT (mIoT) platform and initiated a randomized, multicenter, controlled trial entitled the 'MIOTIC study' to investigate the influence of mIoT among stable COPD patients. In the MIOTIC study, at least 600 patients with stable GOLD group C or D COPD and with a history of at least two moderate-to-severe exacerbations within the previous year will be randomly allocated to the control group, which receives routine follow-up, or the intervention group, which receives mIoT management. Endpoints of the study include (1) frequency and severity of acute exacerbation; (2) symptomatic evaluation; (3) pre- and post-bronchodilator forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FVC) measurement; (4) exercise capacity; and (5) direct medical cost per year. Results from this study should provide direct evidence for the suitability of mIoT in stable COPD patient management.
Electroless plating apparatus for discrete microsized particles
International Nuclear Information System (INIS)
Mayer, A.
1978-01-01
Method and apparatus are disclosed for producing very uniform coatings of a desired material on discrete microsized particles by electroless techniques. Agglomeration or bridging of the particles during the deposition process is prevented by imparting a sufficiently random motion to the particles that they are not in contact with each other for a time sufficient for such to occur
Seok, Junhee; Seon Kang, Yeong
2015-06-05
Mutual information, a general measure of the relatedness between two random variables, has been actively used in the analysis of biomedical data. The mutual information between two discrete variables is conventionally calculated by their joint probabilities estimated from the frequency of observed samples in each combination of variable categories. However, this conventional approach is no longer efficient for discrete variables with many categories, which can be easily found in large-scale biomedical data such as diagnosis codes, drug compounds, and genotypes. Here, we propose a method to provide stable estimations for the mutual information between discrete variables with many categories. Simulation studies showed that the proposed method reduced the estimation errors by 45 folds and improved the correlation coefficients with true values by 99 folds, compared with the conventional calculation of mutual information. The proposed method was also demonstrated through a case study for diagnostic data in electronic health records. This method is expected to be useful in the analysis of various biomedical data with discrete variables.
International Nuclear Information System (INIS)
Williams, Ruth M
2006-01-01
A review is given of a number of approaches to discrete quantum gravity, with a restriction to those likely to be relevant in four dimensions. This paper is dedicated to Rafael Sorkin on the occasion of his sixtieth birthday
Finite Discrete Gabor Analysis
DEFF Research Database (Denmark)
Søndergaard, Peter Lempel
2007-01-01
on the real line to be well approximated by finite and discrete Gabor frames. This method of approximation is especially attractive because efficient numerical methods exists for doing computations with finite, discrete Gabor systems. This thesis presents new algorithms for the efficient computation of finite......, discrete Gabor coefficients. Reconstruction of a signal from its Gabor coefficients is done by the use of a so-called dual window. This thesis presents a number of iterative algorithms to compute dual and self-dual windows. The Linear Time Frequency Toolbox is a Matlab/Octave/C toolbox for doing basic...... discrete time/frequency and Gabor analysis. It is intended to be both an educational and a computational tool. The toolbox was developed as part of this Ph.D. project to provide a solid foundation for the field of computational Gabor analysis....
Goodrich, Christopher
2015-01-01
This text provides the first comprehensive treatment of the discrete fractional calculus. Experienced researchers will find the text useful as a reference for discrete fractional calculus and topics of current interest. Students who are interested in learning about discrete fractional calculus will find this text to provide a useful starting point. Several exercises are offered at the end of each chapter and select answers have been provided at the end of the book. The presentation of the content is designed to give ample flexibility for potential use in a myriad of courses and for independent study. The novel approach taken by the authors includes a simultaneous treatment of the fractional- and integer-order difference calculus (on a variety of time scales, including both the usual forward and backwards difference operators). The reader will acquire a solid foundation in the classical topics of the discrete calculus while being introduced to exciting recent developments, bringing them to the frontiers of the...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 1. Discrete Event Simulation. Matthew Jacob ... Keywords. Simulation; modelling; computer programming. Author Affiliations. Matthew Jacob1. Department of Computer Science and Automation, Indian Institute of Science, Bangalore 560 012.
The Discrete Wavelet Transform
1991-06-01
B-1 ,.iii FIGURES 1.1 A wavelet filter bank structure ..................................... 2 2.1 Diagram illustrating the dialation and...abstract decompositions of discrete time series. Their wide sweeping significance, however, lies in their interpretation as wavelet transforms. In a general...parameter transform wn in the scale- time plane. Following terminology to be intro- duced, wi is the (decimated) discrete wavelet transform. become the
Indian Academy of Sciences (India)
\\;j t E ~. On the other hand, if the signal is defined only at discrete instants of time and not elsewhere i.e., t takes on only the discrete values t = kT for some range of integer values of k, the signal ... is applied to an electronic switch that is closed for a mo- ment every ... ture (T = 1 hour), banking transactions (T = ~ year), census.
Discrete computational structures
Korfhage, Robert R
1974-01-01
Discrete Computational Structures describes discrete mathematical concepts that are important to computing, covering necessary mathematical fundamentals, computer representation of sets, graph theory, storage minimization, and bandwidth. The book also explains conceptual framework (Gorn trees, searching, subroutines) and directed graphs (flowcharts, critical paths, information network). The text discusses algebra particularly as it applies to concentrates on semigroups, groups, lattices, propositional calculus, including a new tabular method of Boolean function minimization. The text emphasize
Kloppenburg, Wybe; Stegeman, CA; Kremer Hovinga, T; Vastenburg, G; Vos, P; de Jong, PE; Huisman, RM
Background. Protein requirements in stable, adequately dialysed haemodialysis patients are not known and recommendations vary. It is not known whether increasing the dialysis dose above the accepted adequate level has a favourable effect on nutrition. The aim of this study was to determine whether
Coverage Probability of Random Intervals
Chen, Xinjia
2007-01-01
In this paper, we develop a general theory on the coverage probability of random intervals defined in terms of discrete random variables with continuous parameter spaces. The theory shows that the minimum coverage probabilities of random intervals with respect to corresponding parameters are achieved at discrete finite sets and that the coverage probabilities are continuous and unimodal when parameters are varying in between interval endpoints. The theory applies to common important discrete ...
Hopf Bifurcation Analysis for a Stochastic Discrete-Time Hyperchaotic System
Directory of Open Access Journals (Sweden)
Jie Ran
2015-01-01
Full Text Available The dynamics of a discrete-time hyperchaotic system and the amplitude control of Hopf bifurcation for a stochastic discrete-time hyperchaotic system are investigated in this paper. Numerical simulations are presented to exhibit the complex dynamical behaviors in the discrete-time hyperchaotic system. Furthermore, the stochastic discrete-time hyperchaotic system with random parameters is transformed into its equivalent deterministic system with the orthogonal polynomial theory of discrete random function. In addition, the dynamical features of the discrete-time hyperchaotic system with random disturbances are obtained through its equivalent deterministic system. By using the Hopf bifurcation conditions of the deterministic discrete-time system, the specific conditions for the existence of Hopf bifurcation in the equivalent deterministic system are derived. And the amplitude control with random intensity is discussed in detail. Finally, the feasibility of the control method is demonstrated by numerical simulations.
DEFF Research Database (Denmark)
Gluud, Christian; Als-Nielsen, Bodil; Damgaard, Morten
2008-01-01
Objectives: We have reported increased 2.6-year mortality in clarithromycin- versus placebo-exposed stable coronary heart disease patients, but meta-analysis of randomized trials in coronary heart disease patients showed no significant effect of antibiotics on mortality. Here we report the 6-year......,372 patients with stable coronary heart disease to clarithromycin 500 mg (n = 2,172) or placebo (n = 2,200) once daily for 2 weeks. Mortality was followed through public register. Nine hundred and twenty-three patients (21.1%) died. Six-year mortality was significantly higher in the clarithromycin group...... disease versus placebo/no intervention (17 trials, 25,271 patients, 1,877 deaths) showed a significantly increased relative risk of death from antibiotics of 1.10 (1.01-1.20) without heterogeneity. Conclusions: Our results stress the necessity to consider carefully the strength of the indication before...
Discrete systems and integrability
Hietarinta, J; Nijhoff, F W
2016-01-01
This first introductory text to discrete integrable systems introduces key notions of integrability from the vantage point of discrete systems, also making connections with the continuous theory where relevant. While treating the material at an elementary level, the book also highlights many recent developments. Topics include: Darboux and Bäcklund transformations; difference equations and special functions; multidimensional consistency of integrable lattice equations; associated linear problems (Lax pairs); connections with Padé approximants and convergence algorithms; singularities and geometry; Hirota's bilinear formalism for lattices; intriguing properties of discrete Painlevé equations; and the novel theory of Lagrangian multiforms. The book builds the material in an organic way, emphasizing interconnections between the various approaches, while the exposition is mostly done through explicit computations on key examples. Written by respected experts in the field, the numerous exercises and the thoroug...
Directory of Open Access Journals (Sweden)
Prateek Sharma
2015-04-01
Full Text Available Abstract Simulation can be regarded as the emulation of the behavior of a real-world system over an interval of time. The process of simulation relies upon the generation of the history of a system and then analyzing that history to predict the outcome and improve the working of real systems. Simulations can be of various kinds but the topic of interest here is one of the most important kind of simulation which is Discrete-Event Simulation which models the system as a discrete sequence of events in time. So this paper aims at introducing about Discrete-Event Simulation and analyzing how it is beneficial to the real world systems.
Introductory discrete mathematics
Balakrishnan, V K
2010-01-01
This concise text offers an introduction to discrete mathematics for undergraduate students in computer science and mathematics. Mathematics educators consider it vital that their students be exposed to a course in discrete methods that introduces them to combinatorial mathematics and to algebraic and logical structures focusing on the interplay between computer science and mathematics. The present volume emphasizes combinatorics, graph theory with applications to some stand network optimization problems, and algorithms to solve these problems.Chapters 0-3 cover fundamental operations involv
International Nuclear Information System (INIS)
Samios, N.P.
1994-01-01
I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets, with a few more additions - with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers - exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the foree of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc. (orig.)
International Nuclear Information System (INIS)
Samios, N.P.
1993-01-01
I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc
A discrete stress-strength interference model based on universal generating function
International Nuclear Information System (INIS)
An Zongwen; Huang Hongzhong; Liu Yu
2008-01-01
Continuous stress-strength interference (SSI) model regards stress and strength as continuous random variables with known probability density function. This, to some extent, results in a limitation of its application. In this paper, stress and strength are treated as discrete random variables, and a discrete SSI model is presented by using the universal generating function (UGF) method. Finally, case studies demonstrate the validity of the discrete model in a variety of circumstances, in which stress and strength can be represented by continuous random variables, discrete random variables, or two groups of experimental data
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 2. Discrete-Time Systems - Why do We Celebrate Birthdays Once a Year? A Ramakalyan P Kavitha S Harini Vijayalakshmi. General Article Volume 5 Issue 2 February 2000 pp 39-49 ...
Directory of Open Access Journals (Sweden)
Pravesh Kumar Bundhun
Full Text Available New research in interventional cardiology has shown the demand for percutaneous coronary interventions (PCI to have increased tremendously. Effective treatment with a lower hospital cost has been the aim of several PCI capable centers. This study aimed to compare the adverse clinical outcomes associated with same day discharge versus overnight stay in the hospital following PCI in a population of randomized patients with stable coronary artery disease (CAD.The National Library of Medicine (MEDLINE/PubMed, the Cochrane Registry of Randomized Controlled Trials and EMBASE databases were searched (from March to June 2016 for randomized trials comparing same-day discharge versus overnight stay in the hospital following PCI. Main endpoints in this analysis included adverse cardiovascular outcomes observed during a 30-day period. Statistical analysis was carried out by the RevMan 5.3 software whereby odds ratios (OR and 95% confidence intervals (CIs were calculated with respect to a fixed or a random effects model.Eight randomized trials with a total number of 3081 patients (1598 patients who were discharged on the same day and 1483 patients who stayed overnight in the hospital were included. Results of this analysis showed that mortality, myocardial infarction (MI and major adverse cardiac events (MACEs were not significantly different between same day discharge versus overnight stay following PCI with OR: 0.22, 95% CI: 0.04-1.35; P = 0.10, OR: 0.68, 95% CI: 0.33-1.41; P = 0.30 and OR: 0.45, 95% CI: 0.20-1.02; P = 0.06 respectively. Blood transfusion and re-hospitalization were also not significantly different between these two groups with OR: 0.64, 95% CI: 0.13-3.21; P = 0.59 and OR: 1.53, 95% CI: 0.88-2.65; P = 0.13 respectively. Similarly, any adverse event, major bleeding and repeated revascularization were also not significantly different between these two groups of patients with stable CAD, with OR: 0.42, 95% CI: 0.05-3.97; P = 0.45, OR: 0
2015-01-01
Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure. I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...
Directory of Open Access Journals (Sweden)
Verbeek Paul A
2012-02-01
Full Text Available Abstract Background The optimal surgical management of dislocated three- and four-part fractures of the proximal humerus in elderly patients remains unclear. Most used techniques are hemiarthroplasty and angle-stable locking compression plate osteosynthesis. In the current literature there is no evidence available presenting superior results between hemiarthroplasty and angle-stable locking compression plate osteosynthesis in terms of speed of recovery, pain, patient satisfaction, functional outcome, quality of life or complications. Methods/Design A randomized controlled multicenter trial will be conducted. Patients older than 60 years of age with a dislocated three- or four-part fracture of the proximal humerus as diagnosed by X-rays and CT-scans will be included. Exclusion criteria are a fracture older than 14 days, multiple comorbidity, multitrauma, a pathological fracture, previous surgery on the injured shoulder, severely deranged function caused by a previous disease, "head-split" proximal humerus fracture and unwillingness or inability to follow instructions. Participants will be randomized between surgical treatment with hemiarthroplasty and angle-stable locking compression plate osteosynthesis. Measurements will take place preoperatively and 3 months, 6 months, 9 months, 12 months and 24 months postoperatively. Primary outcome measure is speed of recovery of functional capacity of the affected upper limb using the Disabilities of Arm, Shoulder and Hand score (DASH. Secondary outcome measures are pain, patient satisfaction, shoulder function, quality of life, radiological evaluation and complications. Data will be analyzed on an intention-to-treat basis, using univariate and multivariate analyses. Discussion Both hemiarthroplasty and angle-stable locking compression plate osteosynthesis are used in the current treatment of dislocated three-and four-part fractures of the proximal humerus. There is a lack of level-1 studies comparing
Exponential-modified discrete Lindley distribution.
Yilmaz, Mehmet; Hameldarbandi, Monireh; Acik Kemaloglu, Sibel
2016-01-01
In this study, we have considered a series system composed of stochastically independent M-component where M is a random variable having the zero truncated modified discrete Lindley distribution. This distribution is newly introduced by transforming on original parameter. The properties of the distribution of the lifetime of above system have been examined under the given circumstances and also parameters of this new lifetime distribution are estimated by using moments, maximum likelihood and EM-algorithm.
Discrete mathematics with applications
Koshy, Thomas
2003-01-01
This approachable text studies discrete objects and the relationsips that bind them. It helps students understand and apply the power of discrete math to digital computer systems and other modern applications. It provides excellent preparation for courses in linear algebra, number theory, and modern/abstract algebra and for computer science courses in data structures, algorithms, programming languages, compilers, databases, and computation.* Covers all recommended topics in a self-contained, comprehensive, and understandable format for students and new professionals * Emphasizes problem-solving techniques, pattern recognition, conjecturing, induction, applications of varying nature, proof techniques, algorithm development and correctness, and numeric computations* Weaves numerous applications into the text* Helps students learn by doing with a wealth of examples and exercises: - 560 examples worked out in detail - More than 3,700 exercises - More than 150 computer assignments - More than 600 writing projects*...
2002-01-01
Discrete geometry investigates combinatorial properties of configurations of geometric objects. To a working mathematician or computer scientist, it offers sophisticated results and techniques of great diversity and it is a foundation for fields such as computational geometry or combinatorial optimization. This book is primarily a textbook introduction to various areas of discrete geometry. In each area, it explains several key results and methods, in an accessible and concrete manner. It also contains more advanced material in separate sections and thus it can serve as a collection of surveys in several narrower subfields. The main topics include: basics on convex sets, convex polytopes, and hyperplane arrangements; combinatorial complexity of geometric configurations; intersection patterns and transversals of convex sets; geometric Ramsey-type results; polyhedral combinatorics and high-dimensional convexity; and lastly, embeddings of finite metric spaces into normed spaces. Jiri Matousek is Professor of Com...
Salinelli, Ernesto
2014-01-01
This book provides an introduction to the analysis of discrete dynamical systems. The content is presented by an unitary approach that blends the perspective of mathematical modeling together with the ones of several discipline as Mathematical Analysis, Linear Algebra, Numerical Analysis, Systems Theory and Probability. After a preliminary discussion of several models, the main tools for the study of linear and non-linear scalar dynamical systems are presented, paying particular attention to the stability analysis. Linear difference equations are studied in detail and an elementary introduction of Z and Discrete Fourier Transform is presented. A whole chapter is devoted to the study of bifurcations and chaotic dynamics. One-step vector-valued dynamical systems are the subject of three chapters, where the reader can find the applications to positive systems, Markov chains, networks and search engines. The book is addressed mainly to students in Mathematics, Engineering, Physics, Chemistry, Biology and Economic...
Time Discretization Techniques
Gottlieb, S.
2016-10-12
The time discretization of hyperbolic partial differential equations is typically the evolution of a system of ordinary differential equations obtained by spatial discretization of the original problem. Methods for this time evolution include multistep, multistage, or multiderivative methods, as well as a combination of these approaches. The time step constraint is mainly a result of the absolute stability requirement, as well as additional conditions that mimic physical properties of the solution, such as positivity or total variation stability. These conditions may be required for stability when the solution develops shocks or sharp gradients. This chapter contains a review of some of the methods historically used for the evolution of hyperbolic PDEs, as well as cutting edge methods that are now commonly used.
Energy Technology Data Exchange (ETDEWEB)
Gambacurta, D.; Grasso, M.; Catara, F. [GANIL,CEA/DSM-CNRS/IN2P3, Caen (France); Institut de Physique Nucleaire, Universite Paris-Sud, IN2P3-CNRS, F-91406 Orsay Cedex (France); Dipartimento di Fisica e Astronomia dell' Universita di and INFN Catania (Italy)
2012-10-20
The low-lying dipole strength distributions of {sup 40}CaCa and {sup 48}Ca, in the energy region between 5 and 10 MeV, are studied within the second random phase approximation (RPA) with Skyrme interaction. Standard RPA models do not usually predict any presence of strength in this energy region, while experimentally a significant amount of strength is found. The inclusion of the 2 particle -2 hole configurations allows to obtain a description in a rather good agreement with the experimental data. The properties of the most collective state are analyzed in terms of its 1 particle -1 hole nature and its transition densities.
Indian Academy of Sciences (India)
the birth rate, d is the death rate and u(k) is the number of net immigrants entering the country in year k. We leave it to the reader to model the vacillating mathe- matician problem [3] as a discrete-time system. General Forms of Difference Equations. An nth order difference equation may be written, typically, either as y(k + n) + ...
International Nuclear Information System (INIS)
Jalnapurkar, Sameer M; Leok, Melvin; Marsden, Jerrold E; West, Matthew
2006-01-01
This paper develops the theory of Abelian Routh reduction for discrete mechanical systems and applies it to the variational integration of mechanical systems with Abelian symmetry. The reduction of variational Runge-Kutta discretizations is considered, as well as the extent to which symmetry reduction and discretization commute. These reduced methods allow the direct simulation of dynamical features such as relative equilibria and relative periodic orbits that can be obscured or difficult to identify in the unreduced dynamics. The methods are demonstrated for the dynamics of an Earth orbiting satellite with a non-spherical J 2 correction, as well as the double spherical pendulum. The J 2 problem is interesting because in the unreduced picture, geometric phases inherent in the model and those due to numerical discretization can be hard to distinguish, but this issue does not appear in the reduced algorithm, where one can directly observe interesting dynamical structures in the reduced phase space (the cotangent bundle of shape space), in which the geometric phases have been removed. The main feature of the double spherical pendulum example is that it has a non-trivial magnetic term in its reduced symplectic form. Our method is still efficient as it can directly handle the essential non-canonical nature of the symplectic structure. In contrast, a traditional symplectic method for canonical systems could require repeated coordinate changes if one is evoking Darboux' theorem to transform the symplectic structure into canonical form, thereby incurring additional computational cost. Our method allows one to design reduced symplectic integrators in a natural way, despite the non-canonical nature of the symplectic structure
Discrete variational Hamiltonian mechanics
International Nuclear Information System (INIS)
Lall, S; West, M
2006-01-01
The main contribution of this paper is to present a canonical choice of a Hamiltonian theory corresponding to the theory of discrete Lagrangian mechanics. We make use of Lagrange duality and follow a path parallel to that used for construction of the Pontryagin principle in optimal control theory. We use duality results regarding sensitivity and separability to show the relationship between generating functions and symplectic integrators. We also discuss connections to optimal control theory and numerical algorithms
Czech Academy of Sciences Publication Activity Database
Mesiar, Radko; Li, J.; Pap, E.
2013-01-01
Roč. 54, č. 3 (2013), s. 357-364 ISSN 0888-613X R&D Projects: GA ČR GAP402/11/0378 Institutional support: RVO:67985556 Keywords : concave integral * pseudo-addition * pseudo- multiplication Subject RIV: BA - General Mathematics Impact factor: 1.977, year: 2013 http://library.utia.cas.cz/separaty/2013/E/mesiar-discrete pseudo-integrals. pdf
Hamiltonian Mechanics on Discrete Manifolds
Talasila, V.; Clemente Gallardo, J.; Schaft, A.J. van der
2004-01-01
The mathematical/geometric structure of discrete models of systems, whether these models are obtained after discretization of a smooth system or as a direct result of modeling at the discrete level, have not been studied much. Mostly one is concerned regarding the nature of the solutions, but not
Directory of Open Access Journals (Sweden)
Wai Kuan Yip
2007-01-01
Full Text Available We introduce a novel method for secure computation of biometric hash on dynamic hand signatures using BioPhasor mixing and discretization. The use of BioPhasor as the mixing process provides a one-way transformation that precludes exact recovery of the biometric vector from compromised hashes and stolen tokens. In addition, our user-specific discretization acts both as an error correction step as well as a real-to-binary space converter. We also propose a new method of extracting compressed representation of dynamic hand signatures using discrete wavelet transform (DWT and discrete fourier transform (DFT. Without the conventional use of dynamic time warping, the proposed method avoids storage of user's hand signature template. This is an important consideration for protecting the privacy of the biometric owner. Our results show that the proposed method could produce stable and distinguishable bit strings with equal error rates (EERs of and for random and skilled forgeries for stolen token (worst case scenario, and for both forgeries in the genuine token (optimal scenario.
Chen, Huangxin
2017-09-01
In this paper we consider the energy stability estimates for some fully discrete schemes which both consider time and spatial discretizations for the incompressible Navier–Stokes equations. We focus on three kinds of fully discrete schemes, i.e., the linear implicit scheme for time discretization with the finite difference method (FDM) on staggered grids for spatial discretization, pressure-correction schemes for time discretization with the FDM on staggered grids for the solutions of the decoupled velocity and pressure equations, and pressure-stabilization schemes for time discretization with the FDM on staggered grids for the solutions of the decoupled velocity and pressure equations. The energy stability estimates are obtained for the above each fully discrete scheme. The upwind scheme is used in the discretization of the convection term which plays an important role in the design of unconditionally stable discrete schemes. Numerical results are given to verify the theoretical analysis.
Fatti, Geoffrey; Ngorima-Mabhena, Nicoletta; Chirowa, Frank; Chirwa, Benson; Takarinda, Kudakwashe; Tafuma, Taurayi A; Mahachi, Nyikadzino; Chikodzore, Rudo; Nyadundu, Simon; Ajayi, Charles A; Mutasa-Apollo, Tsitsi; Mugurungi, Owen; Mothibi, Eula; Hoffman, Risa M; Grimwood, Ashraf
2018-01-29
Sub-Saharan Africa is the world region with the greatest number of people eligible to receive antiretroviral treatment (ART). Less frequent dispensing of ART and community-based ART-delivery models are potential strategies to reduce the load on overburdened healthcare facilities and reduce the barriers for patients to access treatment. However, no large-scale trials have been conducted investigating patient outcomes or evaluating the cost-effectiveness of extended ART-dispensing intervals within community ART-delivery models. This trial will assess the clinical effectiveness, cost-effectiveness and acceptability of providing ART refills on a 3 vs. a 6-monthly basis within community ART-refill groups (CARGs) for stable patients in Zimbabwe. In this pragmatic, three-arm, parallel, unblinded, cluster-randomized non-inferiority trial, 30 clusters (healthcare facilities and associated CARGs) are allocated using stratified randomization in a 1:1:1 ratio to either (1) ART refills supplied 3-monthly from the health facility (control arm), (2) ART refills supplied 3-monthly within CARGs, or (3) ART refills supplied 6-monthly within CARGs. A CARG consists of 6-12 stable patients who meet in the community to receive ART refills and who provide support to one another. Stable adult ART patients with a baseline viral load alive and retained in care 12 months after enrollment. Secondary outcomes (measured at 12 and 24 months) are the proportions achieving virological suppression, average provider cost per participant, provider cost per participant retained, cost per participant retained with virological suppression, and average patient-level costs to access treatment. Qualitative research will assess the acceptability of extended ART-dispensing intervals within CARGs to both providers and patients, and indicators of potential facility-level decongestion due to the interventions will be assessed. Cost-effective health system models that sustain high levels of patient retention
Dynamics of breathers in discrete nonlinear Schrodinger models
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Johansson, Magnus; Aubry, Serge
1998-01-01
We review some recent results concerning the existence and stability of spatially localized and temporally quasiperiodic (non-stationary) excitations in discrete nonlinear Schrodinger (DNLS) models. In two dimensions, we show the existence of linearly stable, stationary and non-stationary localiz...... equation where bistability occurs, a controlled switching between stable states is possible by exciting an internal breathing mode above a threshold value. (C) 1998 Elsevier Science B.V....
Brauer, Fred; Feng, Zhilan; Castillo-Chavez, Carlos
2010-01-01
The mathematical theory of single outbreak epidemic models really began with the work of Kermack and Mackendrick about decades ago. This gave a simple answer to the long-standing question of why epidemics woould appear suddenly and then disappear just as suddenly without having infected an entire population. Therefore it seemed natural to expect that theoreticians would immediately proceed to expand this mathematical framework both because the need to handle recurrent single infectious disease outbreaks has always been a priority for public health officials and because theoreticians often try to push the limits of exiting theories. However, the expansion of the theory via the inclusion of refined epidemiological classifications or through the incorporation of categories that are essential for the evaluation of intervention strategies, in the context of ongoing epidemic outbreaks, did not materialize. It was the global threat posed by SARS in that caused theoreticians to expand the Kermack-McKendrick single-outbreak framework. Most recently, efforts to connect theoretical work to data have exploded as attempts to deal with the threat of emergent and re-emergent diseases including the most recent H1N1 influenza pandemic, have marched to the forefront of our global priorities. Since data are collected and/or reported over discrete units of time, developing single outbreak models that fit collected data naturally is relevant. In this note, we introduce a discrete-epidemic framework and highlight, through our analyses, the similarities between single-outbreak comparable classical continuous-time epidemic models and the discrete-time models introduced in this note. The emphasis is on comparisons driven by expressions for the final epidemic size.
Kim, Joo Hyung; Kang, Tae Sung; Yang, Jung Yup; Hong, Jin Pyo
2015-01-01
One long-standing goal in the emerging field of flexible and transparent electronic devices is to meet the demand of key markets, such as enhanced output performance for metal oxide semiconductor thin film transistors (TFTs) prepared by a solution process. While solution-based fabrication techniques are cost-effective and ensure large-area coverage at low temperature, their utilization has the disadvantage of introducing large trap states into TFTs. Such states, the formation of which is induced by intrinsic defects initially produced during preparation, have a significant impact on electrical performance. Therefore, the ability to enhance the electrical characteristics of solution-processed TFTs, along with attaining a firm understanding of their physical nature, remains a key step towards extending their use. In this study, measurements of low-frequency noise and random telegraph signal noise are employed as generic alternative tools to examine the origins of enhanced output performance for solution-processed ZnO TFTs through the control of defect sites by Al evaporation. PMID:26525284
Discrete mechanics Based on Finite Element Methods
Chen, Jing-bo; Guo, Han-Ying; Wu, Ke
2002-01-01
Discrete Mechanics based on finite element methods is presented in this paper. We also explore the relationship between this discrete mechanics and Veselov discrete mechanics. High order discretizations are constructed in terms of high order interpolations.
Robust discrete-time nonlinear sliding mode controller with plant ...
African Journals Online (AJOL)
This paper addresses the new control algorithm, by designing the asymptotically stable nonlinear sliding surface with investigation of the states. This proposed algorithm leads to solve the problem of unstable systems, by proving the asymptotic stability of a class of uncertain discrete-time systems. A particular linear ...
International Nuclear Information System (INIS)
Souza, Manoelito M. de
1997-01-01
We discuss the physical meaning and the geometric interpretation of implementation in classical field theories. The origin of infinities and other inconsistencies in field theories is traced to fields defined with support on the light cone; a finite and consistent field theory requires a light-cone generator as the field support. Then, we introduce a classical field theory with support on the light cone generators. It results on a description of discrete (point-like) interactions in terms of localized particle-like fields. We find the propagators of these particle-like fields and discuss their physical meaning, properties and consequences. They are conformally invariant, singularity-free, and describing a manifestly covariant (1 + 1)-dimensional dynamics in a (3 = 1) spacetime. Remarkably this conformal symmetry remains even for the propagation of a massive field in four spacetime dimensions. We apply this formalism to Classical electrodynamics and to the General Relativity Theory. The standard formalism with its distributed fields is retrieved in terms of spacetime average of the discrete field. Singularities are the by-products of the averaging process. This new formalism enlighten the meaning and the problem of field theory, and may allow a softer transition to a quantum theory. (author)
Discretization of time series data.
Dimitrova, Elena S; Licona, M Paola Vera; McGee, John; Laubenbacher, Reinhard
2010-06-01
An increasing number of algorithms for biochemical network inference from experimental data require discrete data as input. For example, dynamic Bayesian network methods and methods that use the framework of finite dynamical systems, such as Boolean networks, all take discrete input. Experimental data, however, are typically continuous and represented by computer floating point numbers. The translation from continuous to discrete data is crucial in preserving the variable dependencies and thus has a significant impact on the performance of the network inference algorithms. We compare the performance of two such algorithms that use discrete data using several different discretization algorithms. One of the inference methods uses a dynamic Bayesian network framework, the other-a time-and state-discrete dynamical system framework. The discretization algorithms are quantile, interval discretization, and a new algorithm introduced in this article, SSD. SSD is especially designed for short time series data and is capable of determining the optimal number of discretization states. The experiments show that both inference methods perform better with SSD than with the other methods. In addition, SSD is demonstrated to preserve the dynamic features of the time series, as well as to be robust to noise in the experimental data. A C++ implementation of SSD is available from the authors at http://polymath.vbi.vt.edu/discretization .
Galerkin v. discrete-optimal projection in nonlinear model reduction
Energy Technology Data Exchange (ETDEWEB)
Carlberg, Kevin Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barone, Matthew Franklin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Antil, Harbir [George Mason Univ., Fairfax, VA (United States)
2015-04-01
Discrete-optimal model-reduction techniques such as the Gauss{Newton with Approximated Tensors (GNAT) method have shown promise, as they have generated stable, accurate solutions for large-scale turbulent, compressible ow problems where standard Galerkin techniques have failed. However, there has been limited comparative analysis of the two approaches. This is due in part to difficulties arising from the fact that Galerkin techniques perform projection at the time-continuous level, while discrete-optimal techniques do so at the time-discrete level. This work provides a detailed theoretical and experimental comparison of the two techniques for two common classes of time integrators: linear multistep schemes and Runge{Kutta schemes. We present a number of new ndings, including conditions under which the discrete-optimal ROM has a time-continuous representation, conditions under which the two techniques are equivalent, and time-discrete error bounds for the two approaches. Perhaps most surprisingly, we demonstrate both theoretically and experimentally that decreasing the time step does not necessarily decrease the error for the discrete-optimal ROM; instead, the time step should be `matched' to the spectral content of the reduced basis. In numerical experiments carried out on a turbulent compressible- ow problem with over one million unknowns, we show that increasing the time step to an intermediate value decreases both the error and the simulation time of the discrete-optimal reduced-order model by an order of magnitude.
Geleijnse, Johanna M; Giltay, Erik J; Kromhout, Daan
2012-07-01
Epidemiological studies suggest a protective effect of n-3 fatty acids derived from fish (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) against cognitive decline. For α-linolenic acid (ALA) obtained from vegetable sources, the effect on cognitive decline is unknown. We examined the effect of n-3 fatty acid supplementation on cognitive decline in coronary heart disease patients. The analysis included 2911 coronary patients (78% men) aged 60 to 80 years who participated in a double-blind placebo-controlled trial of n-3 fatty acids and cardiovascular diseases (Alpha Omega Trial). By using a 2 × 2 factorial design, patients were randomly assigned to margarines that provided 400 mg/d of EPA-DHA, 2 g/d of ALA, both EPA-DHA and ALA, or placebo for 40 months. Cognitive function was assessed by the Mini-Mental State Examination (MMSE) at baseline and after 40 months. The effect of n-3 fatty acids on change in MMSE score was assessed using analysis of variance. Logistic regression analysis was used to examine the effects on risk of cognitive decline, defined as a decrease of 3 or more points in MMSE score or incidence of dementia. Patients in the active treatment groups had an additional intake of 384 mg of EPA-DHA, 1.9 g of ALA, or both. The overall MMSE score in this cohort was 28.3 ± 1.6 points, which decreased by 0.67 ± 2.25 points during follow-up. Changes in MMSE score during intervention did not differ significantly between EPA-DHA and placebo (-0.65 vs -0.69 points, P = .44) or between ALA and placebo (-0.60 vs -0.74 points, P = .12). The risk of cognitive decline was 1.03 (95% confidence interval: 0.84-1.26, P = .80) for EPA-DHA (vs placebo) and 0.90 (0.74-1.10, P = .31) for ALA (vs placebo). This large intervention study showed no effect of dietary doses of n-3 fatty acids on global cognitive decline in coronary heart disease patients. Copyright © 2012 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.
Pedersen, Lene Rørholm; Olsen, Rasmus Huan; Anholm, Christian; Walzem, Rosemary L; Fenger, Mogens; Eugen-Olsen, Jesper; Haugaard, Steen Bendix; Prescott, Eva
2016-03-01
Dyslipidemia and low-grade inflammation are integral in the pathogenesis of atherosclerosis. We aim to compare the effects of a considerable weight loss and intensive exercise training on lipid atherogenicity and low-grade inflammation in a high-risk population with coronary artery disease (CAD). Seventy non-diabetic participants with CAD, BMI 28-40 kg/m(2), age 45-75 years were randomized to 12 weeks' aerobic interval training (AIT) at 85-90% of peak heart rate three times/week or a low energy diet (LED, 800-1000 kcal/day) for 8-10 weeks followed by 2-4 weeks' weight maintenance diet. Lipid profile atherogenicity was described using lipoprotein particle size and density profiling. Low-grade inflammation was evaluated by tumor necrosis factor alpha (TNFα), C-reactive protein, interleukin 6 and soluble urokinase plasminogen activator receptor. Twenty-six (74%) AIT and 29 (83%) LED participants completed intervention per protocol. AIT and LED decreased total (AIT: -518 {-906;-129},P = 0.011, LED: -767 {-1128:-406},P < 0.001) and low-density lipoprotein (LDL, AIT: -186 {-306;-65},P = 0.004, LED: -277 {-433;-122},P < 0.001) assessed as the area under the density profile curve. LED was superior to AIT in decreasing atherogenicity reflected by increased LDL (between-group: 1.0 Å {0.4; 1.7},P = 0.003) and high-density lipoprotein (between-group: 1.2 Å {0.2; 2.4},P = 0.026) particle size and a decreased proportion of total lipoprotein constituted by the small, dense LDL5 subfraction (between-group: -5.0% {-8.4;-1.7},P = 0.004). LED decreased TNFα (9.5% {-15.8;-2.6},P = 0.009). No changes were seen following AIT. LED and AIT decreased total and LDL lipoprotein. LED was superior in decreasing atherogenicity assessed by a shift in density profile and increased particle size. Effect on low-grade inflammation was limited. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Discrete Exterior Calculus Discretization of Incompressible Navier-Stokes Equations
Mohamed, Mamdouh S.
2017-05-23
A conservative discretization of incompressible Navier-Stokes equations over surface simplicial meshes is developed using discrete exterior calculus (DEC). Numerical experiments for flows over surfaces reveal a second order accuracy for the developed scheme when using structured-triangular meshes, and first order accuracy otherwise. The mimetic character of many of the DEC operators provides exact conservation of both mass and vorticity, in addition to superior kinetic energy conservation. The employment of barycentric Hodge star allows the discretization to admit arbitrary simplicial meshes. The discretization scheme is presented along with various numerical test cases demonstrating its main characteristics.
Linearity stabilizes discrete breathers
Indian Academy of Sciences (India)
rable strength) in eq. (2). When α = 0,β = 1, such a perturbation results in both a stable propagating compression pulse (solitary wave), and an identical and opposite .... with its three branches, is missing in this situation where α is comparable in strength with β. ... 300 time units at the end of the computational exercise.
Geometric theory of discrete nonautonomous dynamical systems
Pötzsche, Christian
2010-01-01
Nonautonomous dynamical systems provide a mathematical framework for temporally changing phenomena, where the law of evolution varies in time due to seasonal, modulation, controlling or even random effects. Our goal is to provide an approach to the corresponding geometric theory of nonautonomous discrete dynamical systems in infinite-dimensional spaces by virtue of 2-parameter semigroups (processes). These dynamical systems are generated by implicit difference equations, which explicitly depend on time. Compactness and dissipativity conditions are provided for such problems in order to have attractors using the natural concept of pullback convergence. Concerning a necessary linear theory, our hyperbolicity concept is based on exponential dichotomies and splittings. This concept is in turn used to construct nonautonomous invariant manifolds, so-called fiber bundles, and deduce linearization theorems. The results are illustrated using temporal and full discretizations of evolutionary differential equations.
Poisson hierarchy of discrete strings
Energy Technology Data Exchange (ETDEWEB)
Ioannidou, Theodora, E-mail: ti3@auth.gr [Faculty of Civil Engineering, School of Engineering, Aristotle University of Thessaloniki, 54249, Thessaloniki (Greece); Niemi, Antti J., E-mail: Antti.Niemi@physics.uu.se [Department of Physics and Astronomy, Uppsala University, P.O. Box 803, S-75108, Uppsala (Sweden); Laboratoire de Mathematiques et Physique Theorique CNRS UMR 6083, Fédération Denis Poisson, Université de Tours, Parc de Grandmont, F37200, Tours (France); Department of Physics, Beijing Institute of Technology, Haidian District, Beijing 100081 (China)
2016-01-28
The Poisson geometry of a discrete string in three dimensional Euclidean space is investigated. For this the Frenet frames are converted into a spinorial representation, the discrete spinor Frenet equation is interpreted in terms of a transfer matrix formalism, and Poisson brackets are introduced in terms of the spinor components. The construction is then generalised, in a self-similar manner, into an infinite hierarchy of Poisson algebras. As an example, the classical Virasoro (Witt) algebra that determines reparametrisation diffeomorphism along a continuous string, is identified as a particular sub-algebra, in the hierarchy of the discrete string Poisson algebra. - Highlights: • Witt (classical Virasoro) algebra is derived in the case of discrete string. • Infinite dimensional hierarchy of Poisson bracket algebras is constructed for discrete strings. • Spinor representation of discrete Frenet equations is developed.
Poisson hierarchy of discrete strings
International Nuclear Information System (INIS)
Ioannidou, Theodora; Niemi, Antti J.
2016-01-01
The Poisson geometry of a discrete string in three dimensional Euclidean space is investigated. For this the Frenet frames are converted into a spinorial representation, the discrete spinor Frenet equation is interpreted in terms of a transfer matrix formalism, and Poisson brackets are introduced in terms of the spinor components. The construction is then generalised, in a self-similar manner, into an infinite hierarchy of Poisson algebras. As an example, the classical Virasoro (Witt) algebra that determines reparametrisation diffeomorphism along a continuous string, is identified as a particular sub-algebra, in the hierarchy of the discrete string Poisson algebra. - Highlights: • Witt (classical Virasoro) algebra is derived in the case of discrete string. • Infinite dimensional hierarchy of Poisson bracket algebras is constructed for discrete strings. • Spinor representation of discrete Frenet equations is developed.
Advances in discrete differential geometry
2016-01-01
This is one of the first books on a newly emerging field of discrete differential geometry and an excellent way to access this exciting area. It surveys the fascinating connections between discrete models in differential geometry and complex analysis, integrable systems and applications in computer graphics. The authors take a closer look at discrete models in differential geometry and dynamical systems. Their curves are polygonal, surfaces are made from triangles and quadrilaterals, and time is discrete. Nevertheless, the difference between the corresponding smooth curves, surfaces and classical dynamical systems with continuous time can hardly be seen. This is the paradigm of structure-preserving discretizations. Current advances in this field are stimulated to a large extent by its relevance for computer graphics and mathematical physics. This book is written by specialists working together on a common research project. It is about differential geometry and dynamical systems, smooth and discrete theories, ...
DISCRETE-TIME VARIABLE STRUCTURE CONTROLLER FOR AIRCRAFT FLIGHT ANGLE TRACKING
Iskrenovic-Momcilovic, Olivera
2014-01-01
The paper presents the longitudinal, short-period aircraft dynamics and its application on the climb angle tracking. For the aircraft flight angle tracking the stable system centre technique is developed for controlling the output in a discrete-time non-minimum phase causal system using the sliding mode control. The developed discrete-time stable system centre technique transforms the output tracking problem to a corresponding state variable tracking problem by asymptotically identifying the ...
Dark discrete gauge symmetries
International Nuclear Information System (INIS)
Batell, Brian
2011-01-01
We investigate scenarios in which dark matter is stabilized by an Abelian Z N discrete gauge symmetry. Models are surveyed according to symmetries and matter content. Multicomponent dark matter arises when N is not prime and Z N contains one or more subgroups. The dark sector interacts with the visible sector through the renormalizable kinetic mixing and Higgs portal operators, and we highlight the basic phenomenology in these scenarios. In particular, multiple species of dark matter can lead to an unconventional nuclear recoil spectrum in direct detection experiments, while the presence of new light states in the dark sector can dramatically affect the decays of the Higgs at the Tevatron and LHC, thus providing a window into the gauge origin of the stability of dark matter.
Immigration and Prosecutorial Discretion.
Apollonio, Dorie; Lochner, Todd; Heddens, Myriah
Immigration has become an increasingly salient national issue in the US, and the Department of Justice recently increased federal efforts to prosecute immigration offenses. This shift, however, relies on the cooperation of US attorneys and their assistants. Traditionally federal prosecutors have enjoyed enormous discretion and have been responsive to local concerns. To consider how the centralized goal of immigration enforcement may have influenced federal prosecutors in regional offices, we review their prosecution of immigration offenses in California using over a decade's worth of data. Our findings suggest that although centralizing forces influence immigration prosecutions, individual US attorneys' offices retain distinct characteristics. Local factors influence federal prosecutors' behavior in different ways depending on the office. Contrary to expectations, unemployment rates did not affect prosecutors' willingness to pursue immigration offenses, nor did local popular opinion about illegal immigration.
Discrete Minimal Surface Algebras
Directory of Open Access Journals (Sweden)
Joakim Arnlind
2010-05-01
Full Text Available We consider discrete minimal surface algebras (DMSA as generalized noncommutative analogues of minimal surfaces in higher dimensional spheres. These algebras appear naturally in membrane theory, where sequences of their representations are used as a regularization. After showing that the defining relations of the algebra are consistent, and that one can compute a basis of the enveloping algebra, we give several explicit examples of DMSAs in terms of subsets of sl_n (any semi-simple Lie algebra providing a trivial example by itself. A special class of DMSAs are Yang-Mills algebras. The representation graph is introduced to study representations of DMSAs of dimension d ≤ 4, and properties of representations are related to properties of graphs. The representation graph of a tensor product is (generically the Cartesian product of the corresponding graphs. We provide explicit examples of irreducible representations and, for coinciding eigenvalues, classify all the unitary representations of the corresponding algebras.
Discrete Pearson distributions
Energy Technology Data Exchange (ETDEWEB)
Bowman, K.O. [Oak Ridge National Lab., TN (United States); Shenton, L.R. [Georgia Univ., Athens, GA (United States); Kastenbaum, M.A. [Kastenbaum (M.A.), Basye, VA (United States)
1991-11-01
These distributions are generated by a first order recursive scheme which equates the ratio of successive probabilities to the ratio of two corresponding quadratics. The use of a linearized form of this model will produce equations in the unknowns matched by an appropriate set of moments (assumed to exist). Given the moments we may find valid solutions. These are two cases; (1) distributions defined on the non-negative integers (finite or infinite) and (2) distributions defined on negative integers as well. For (1), given the first four moments, it is possible to set this up as equations of finite or infinite degree in the probability of a zero occurrence, the sth component being a product of s ratios of linear forms in this probability in general. For (2) the equation for the zero probability is purely linear but may involve slowly converging series; here a particular case is the discrete normal. Regions of validity are being studied. 11 refs.
Principles of discrete time mechanics
Jaroszkiewicz, George
2014-01-01
Could time be discrete on some unimaginably small scale? Exploring the idea in depth, this unique introduction to discrete time mechanics systematically builds the theory up from scratch, beginning with the historical, physical and mathematical background to the chronon hypothesis. Covering classical and quantum discrete time mechanics, this book presents all the tools needed to formulate and develop applications of discrete time mechanics in a number of areas, including spreadsheet mechanics, classical and quantum register mechanics, and classical and quantum mechanics and field theories. A consistent emphasis on contextuality and the observer-system relationship is maintained throughout.
Liu, Hongjian; Wang, Zidong; Shen, Bo; Huang, Tingwen; Alsaadi, Fuad E
2018-06-01
This paper is concerned with the globally exponential stability problem for a class of discrete-time stochastic memristive neural networks (DSMNNs) with both leakage delays as well as probabilistic time-varying delays. For the probabilistic delays, a sequence of Bernoulli distributed random variables is utilized to determine within which intervals the time-varying delays fall at certain time instant. The sector-bounded activation function is considered in the addressed DSMNN. By taking into account the state-dependent characteristics of the network parameters and choosing an appropriate Lyapunov-Krasovskii functional, some sufficient conditions are established under which the underlying DSMNN is globally exponentially stable in the mean square. The derived conditions are made dependent on both the leakage and the probabilistic delays, and are therefore less conservative than the traditional delay-independent criteria. A simulation example is given to show the effectiveness of the proposed stability criterion. Copyright © 2018 Elsevier Ltd. All rights reserved.
Dynamical Localization for Discrete Anderson Dirac Operators
Prado, Roberto A.; de Oliveira, César R.; Carvalho, Silas L.
2017-04-01
We establish dynamical localization for random Dirac operators on the d-dimensional lattice, with d\\in { 1, 2, 3} , in the three usual regimes: large disorder, band edge and 1D. These operators are discrete versions of the continuous Dirac operators and consist in the sum of a discrete free Dirac operator with a random potential. The potential is a diagonal matrix formed by different scalar potentials, which are sequences of independent and identically distributed random variables according to an absolutely continuous probability measure with bounded density and of compact support. We prove the exponential decay of fractional moments of the Green function for such models in each of the above regimes, i.e., (j) throughout the spectrum at larger disorder, (jj) for energies near the band edges at arbitrary disorder and (jjj) in dimension one, for all energies in the spectrum and arbitrary disorder. Dynamical localization in theses regimes follows from the fractional moments method. The result in the one-dimensional regime contrast with one that was previously obtained for 1D Dirac model with Bernoulli potential.
Jung, Segun; Bi, Yingtao; Davuluri, Ramana V
2015-01-01
Many supervised learning algorithms have been applied in deriving gene signatures for patient stratification from gene expression data. However, transferring the multi-gene signatures from one analytical platform to another without loss of classification accuracy is a major challenge. Here, we compared three unsupervised data discretization methods--Equal-width binning, Equal-frequency binning, and k-means clustering--in accurately classifying the four known subtypes of glioblastoma multiforme (GBM) when the classification algorithms were trained on the isoform-level gene expression profiles from exon-array platform and tested on the corresponding profiles from RNA-seq data. We applied an integrated machine learning framework that involves three sequential steps; feature selection, data discretization, and classification. For models trained and tested on exon-array data, the addition of data discretization step led to robust and accurate predictive models with fewer number of variables in the final models. For models trained on exon-array data and tested on RNA-seq data, the addition of data discretization step dramatically improved the classification accuracies with Equal-frequency binning showing the highest improvement with more than 90% accuracies for all the models with features chosen by Random Forest based feature selection. Overall, SVM classifier coupled with Equal-frequency binning achieved the best accuracy (> 95%). Without data discretization, however, only 73.6% accuracy was achieved at most. The classification algorithms, trained and tested on data from the same platform, yielded similar accuracies in predicting the four GBM subgroups. However, when dealing with cross-platform data, from exon-array to RNA-seq, the classifiers yielded stable models with highest classification accuracies on data transformed by Equal frequency binning. The approach presented here is generally applicable to other cancer types for classification and identification of
Finite strain discrete dislocation plasticity
Deshpande, VS; Needleman, A; Van der Giessen, E
2003-01-01
A framework for carrying out finite deformation discrete dislocation plasticity calculations is presented. The discrete dislocations are presumed to be adequately represented by the singular linear elastic fields so that the large deformations near dislocation cores are not modeled. The finite
Multiscale expansions in discrete world
Indian Academy of Sciences (India)
... multiscale expansions discretely. The power of this manageable method is confirmed by applying it to two selected nonlinear Schrödinger evolution equations. This approach can also be applied to other nonlinear discrete evolution equations. All the computations have been made with Maple computer packet program.
Multiscale expansions in discrete world
Indian Academy of Sciences (India)
This approach can also be applied to other nonlinear discrete evolution equations. All the computations have been made with Maple computer packet program. Keywords. Multiscale expansion; discrete evolution equation; modified nonlinear Schrödinger equation; third-order nonlinear Schrödinger equation; KdV equation.
Discrete Mathematics and Its Applications
Oxley, Alan
2010-01-01
The article gives ideas that lecturers of undergraduate Discrete Mathematics courses can use in order to make the subject more interesting for students and encourage them to undertake further studies in the subject. It is possible to teach Discrete Mathematics with little or no reference to computing. However, students are more likely to be…
Modern approaches to discrete curvature
Romon, Pascal
2017-01-01
This book provides a valuable glimpse into discrete curvature, a rich new field of research which blends discrete mathematics, differential geometry, probability and computer graphics. It includes a vast collection of ideas and tools which will offer something new to all interested readers. Discrete geometry has arisen as much as a theoretical development as in response to unforeseen challenges coming from applications. Discrete and continuous geometries have turned out to be intimately connected. Discrete curvature is the key concept connecting them through many bridges in numerous fields: metric spaces, Riemannian and Euclidean geometries, geometric measure theory, topology, partial differential equations, calculus of variations, gradient flows, asymptotic analysis, probability, harmonic analysis, graph theory, etc. In spite of its crucial importance both in theoretical mathematics and in applications, up to now, almost no books have provided a coherent outlook on this emerging field.
Discrete-time variable structure system synthesis for plants with nonminimum phase zeros
Directory of Open Access Journals (Sweden)
Iskrenović-Momčilović Olivera I.
2014-01-01
Full Text Available This paper analyzes a discrete variable structure system for control n-th order plants with nonminimum phase zeros in the input-output transfer function. The problem is solved by using the technique of stable system center. The first is a discrete mathematical model of the system in the normal canonical form for a given system. Then the synthesis of state generator and discrete 'time controller using the center of a stable system. The theoretical results are demonstrated in a numerical example.
Image Retrieval Algorithm Based on Discrete Fractional Transforms
Jindal, Neeru; Singh, Kulbir
2013-06-01
The discrete fractional transforms is a signal processing tool which suggests computational algorithms and solutions to various sophisticated applications. In this paper, a new technique to retrieve the encrypted and scrambled image based on discrete fractional transforms has been proposed. Two-dimensional image was encrypted using discrete fractional transforms with three fractional orders and two random phase masks placed in the two intermediate planes. The significant feature of discrete fractional transforms benefits from its extra degree of freedom that is provided by its fractional orders. Security strength was enhanced (1024!)4 times by scrambling the encrypted image. In decryption process, image retrieval is sensitive for both correct fractional order keys and scrambling algorithm. The proposed approach make the brute force attack infeasible. Mean square error and relative error are the recital parameters to verify validity of proposed method.
Zacharias, Konstantinos; Ahmed, Asrar; Shah, Benoy N; Gurunathan, Sothinathan; Young, Grace; Acosta, Dionisio; Senior, Roxy
2017-02-01
Exercise electrocardiography (ExECG) is widely used in suspected stable angina (SA) as the initial test for the evaluation of coronary artery disease (CAD). We hypothesized that exercise stress echo (ESE) would be efficacious with cost advantage over ExECG when utilized as the initial test. Consecutive patients with suspected SA, without known CAD were randomized into ExECG or ESE. Patients with positive tests were offered coronary angiography (CA) and with inconclusive tests were referred for further investigations. All patients were followed-up for cardiac events (death, myocardial infarction, and unplanned revascularization). Cost to diagnosis of CAD was calculated by adding the cost of all investigations, up to and including CA. In the 194 and 191 patients in the ExECG vs. ESE groups, respectively, pre-test probability of CAD was similar (34 ± 23 vs. 35 ± 25%, P = 0.6). Results of ExECG were: 108 (55.7%) negative, 14 (7.2%) positive, 72 (37.1%) inconclusive and of ESE were 181 (94.8%) negative, 9 (4.7%) positive, 1 (0.5%) inconclusive, respectively. Patients with obstructive CAD following positive ESE vs. Ex ECG were 9/9 vs. 9/14, respectively (P = 0.04). Cost to diagnosis of CAD was £266 for ESE vs. £327 for ExECG (P = 0.005). Over a mean follow-up period of 21 ± 5 months, event rates were similar between the two groups. In this first randomized study, ESE was more efficacious and demonstrated superior cost-saving, compared with ExECG when used as the initial investigation for the evaluation of CAD in patients with new-onset suspected SA without known CAD. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.
Discrete dynamics versus analytic dynamics
DEFF Research Database (Denmark)
Toxværd, Søren
2014-01-01
For discrete classical Molecular dynamics obtained by the “Verlet” algorithm (VA) with the time increment h there exists a shadow Hamiltonian H˜ with energy E˜(h) , for which the discrete particle positions lie on the analytic trajectories for H˜ . Here, we proof that there, independent of such a......For discrete classical Molecular dynamics obtained by the “Verlet” algorithm (VA) with the time increment h there exists a shadow Hamiltonian H˜ with energy E˜(h) , for which the discrete particle positions lie on the analytic trajectories for H˜ . Here, we proof that there, independent...... of such an analytic analogy, exists an exact hidden energy invariance E * for VA dynamics. The fact that the discrete VA dynamics has the same invariances as Newtonian dynamics raises the question, which of the formulations that are correct, or alternatively, the most appropriate formulation of classical dynamics....... In this context the relation between the discrete VA dynamics and the (general) discrete dynamics investigated by Lee [Phys. Lett. B122, 217 (1983)] is presented and discussed....
National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...
Rumor Processes on and Discrete Renewal Processes
Gallo, Sandro; Garcia, Nancy L.; Junior, Valdivino Vargas; Rodríguez, Pablo M.
2014-05-01
We study two rumor processes on , the dynamics of which are related to an SI epidemic model with long range transmission. Both models start with one spreader at site and ignorants at all the other sites of , but differ by the transmission mechanism. In one model, the spreaders transmit the information within a random distance on their right, and in the other the ignorants take the information from a spreader within a random distance on their left. We obtain the probability of survival, information on the distribution of the range of the rumor and limit theorems for the proportion of spreaders. The key step of our proofs is to show that, in each model, the position of the spreaders on can be related to a suitably chosen discrete renewal process.
Batch arrival discrete time queue with gated vacation system ...
African Journals Online (AJOL)
A class of single server vacation queues, which have batch arrivals and single server, is considered in discrete time. Here the server goes on vacation of random length as soon as the system becomes empty. On return from vacation, if he finds any customers waiting in the queue, the server starts serving the customers one ...
Interventional tool tracking using discrete optimization.
Heibel, Hauke; Glocker, Ben; Groher, Martin; Pfister, Marcus; Navab, Nassir
2013-03-01
This work presents a novel scheme for tracking of motion and deformation of interventional tools such as guide-wires and catheters in fluoroscopic X-ray sequences. Being able to track and thus to estimate the correct positions of these tools is crucial in order to offer guidance enhancement during interventions. The task of estimating the apparent motion is particularly challenging due to the low signal-to-noise ratio (SNR) of fluoroscopic images and due to combined motion components originating from patient breathing and tool interactions performed by the physician. The presented approach is based on modeling interventional tools with B-splines whose optimal configuration of control points is determined through efficient discrete optimization. Each control point corresponds to a discrete random variable in a Markov random field (MRF) formulation where a set of labels represents the deformation space. In this context, the optimal curve corresponds to the maximum a posteriori (MAP) estimate of the MRF energy. The main motivation for employing a discrete approach is the possibility to incorporate a multi-directional search space which is robust to local minima. This is of particular interest for curve tracking under large deformation. This work analyzes feasibility of employing efficient first-order MRFs for tracking. In particular it shows how to achieve a good compromise between energy approximations and computational efficiency. Experimental results suggest to define both the external and internal energy in terms of pairwise potential functions. The method was successfully applied to the tracking of guide-wires in fluoroscopic X-ray sequences of several hundred frames which requires extremely robust techniques. Comparisons with state-of-the-art guide-wire tracking algorithms confirm the effectiveness of the proposed method.
Multigrid and Krylov Subspace Methods for the Discrete Stokes Equations
Elman, Howard C.
1996-01-01
Discretization of the Stokes equations produces a symmetric indefinite system of linear equations. For stable discretizations, a variety of numerical methods have been proposed that have rates of convergence independent of the mesh size used in the discretization. In this paper, we compare the performance of four such methods: variants of the Uzawa, preconditioned conjugate gradient, preconditioned conjugate residual, and multigrid methods, for solving several two-dimensional model problems. The results indicate that where it is applicable, multigrid with smoothing based on incomplete factorization is more efficient than the other methods, but typically by no more than a factor of two. The conjugate residual method has the advantage of being both independent of iteration parameters and widely applicable.
Exact analysis of discrete data
Hirji, Karim F
2005-01-01
Researchers in fields ranging from biology and medicine to the social sciences, law, and economics regularly encounter variables that are discrete or categorical in nature. While there is no dearth of books on the analysis and interpretation of such data, these generally focus on large sample methods. When sample sizes are not large or the data are otherwise sparse, exact methods--methods not based on asymptotic theory--are more accurate and therefore preferable.This book introduces the statistical theory, analysis methods, and computation techniques for exact analysis of discrete data. After reviewing the relevant discrete distributions, the author develops the exact methods from the ground up in a conceptually integrated manner. The topics covered range from univariate discrete data analysis, a single and several 2 x 2 tables, a single and several 2 x K tables, incidence density and inverse sampling designs, unmatched and matched case -control studies, paired binary and trinomial response models, and Markov...
Causal Dynamics of Discrete Surfaces
Directory of Open Access Journals (Sweden)
Pablo Arrighi
2014-03-01
Full Text Available We formalize the intuitive idea of a labelled discrete surface which evolves in time, subject to two natural constraints: the evolution does not propagate information too fast; and it acts everywhere the same.
Analysis of stochastic effects in Kaldor-type business cycle discrete model
Bashkirtseva, Irina; Ryashko, Lev; Sysolyatina, Anna
2016-07-01
We study nonlinear stochastic phenomena in the discrete Kaldor model of business cycles. A numerical parametric analysis of stochastically forced attractors (equilibria, closed invariant curves, discrete cycles) of this model is performed using the stochastic sensitivity functions technique. A spatial arrangement of random states in stochastic attractors is modeled by confidence domains. The phenomenon of noise-induced transitions ;chaos-order; is discussed.
Alfa, Attahiru S
2016-01-01
This book introduces the theoretical fundamentals for modeling queues in discrete-time, and the basic procedures for developing queuing models in discrete-time. There is a focus on applications in modern telecommunication systems. It presents how most queueing models in discrete-time can be set up as discrete-time Markov chains. Techniques such as matrix-analytic methods (MAM) that can used to analyze the resulting Markov chains are included. This book covers single node systems, tandem system and queueing networks. It shows how queues with time-varying parameters can be analyzed, and illustrates numerical issues associated with computations for the discrete-time queueing systems. Optimal control of queues is also covered. Applied Discrete-Time Queues targets researchers, advanced-level students and analysts in the field of telecommunication networks. It is suitable as a reference book and can also be used as a secondary text book in computer engineering and computer science. Examples and exercises are includ...
On the discretization and control of an SEIR epidemic model with a periodic impulsive vaccination
Alonso-Quesada, S.; De la Sen, M.; Ibeas, A.
2017-01-01
This paper deals with the discretization and control of an SEIR epidemic model. Such a model describes the transmission of an infectious disease among a time-varying host population. The model assumes mortality from causes related to the disease. Our study proposes a discretization method including a free-design parameter to be adjusted for guaranteeing the positivity of the resulting discrete-time model. Such a method provides a discrete-time model close to the continuous-time one without the need for the sampling period to be as small as other commonly used discretization methods require. This fact makes possible the design of impulsive vaccination control strategies with less burden of measurements and related computations if one uses the proposed instead of other discretization methods. The proposed discretization method and the impulsive vaccination strategy designed on the resulting discretized model are the main novelties of the paper. The paper includes (i) the analysis of the positivity of the obtained discrete-time SEIR model, (ii) the study of stability of the disease-free equilibrium point of a normalized version of such a discrete-time model and (iii) the existence and the attractivity of a globally asymptotically stable disease-free periodic solution under a periodic impulsive vaccination. Concretely, the exposed and infectious subpopulations asymptotically converge to zero as time tends to infinity while the normalized subpopulations of susceptible and recovered by immunization individuals oscillate in the context of such a solution. Finally, a numerical example illustrates the theoretic results.
Bissonnette, Robert; Luchi, Monica; Fidelus-Gort, Rosanne; Jackson, Shawnta; Zhang, Haifeng; Flores, Robert; Newton, Robert; Scherle, Peggy; Yeleswaram, Swamy; Chen, Xuejun; Menter, Alan
2016-08-01
Chronic plaque psoriasis is partially mediated by elevation of proinflammatory cytokines, including several within the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. To evaluate the safety and efficacy of the oral selective JAK1 inhibitor INCB039110 in stable, chronic plaque psoriasis. This was a phase 2, randomized, double-blind, placebo-controlled, dose-escalation study of INCB039110 (100 mg once daily, 200 mg once daily, 200 mg twice daily and 600 mg once daily) for 28 days. The primary endpoint was mean percent change from baseline in the static Physician Global Assessment (sPGA) at day 28. The protocol was institutional review board approved. Of 50 patients, 48 completed the study. At day 28, mean percent reduction from baseline in sPGA was 22.2% for INCB039110 100 mg once daily (p = 0.270 vs. placebo), 29.4% for 200 mg once daily (p = 0.118), 35.2% for 200 mg twice daily (p = 0.053), 42.4% for 600 mg once daily (p = 0.003) and 12.5% for placebo. Across groups, 11.1% to 45.5% achieved an sPGA score of 1 versus 0% for placebo. INCB039110 was generally well tolerated; the most common treatment-emergent adverse event was nasopharyngitis (18.4%). INCB039110 produced significant improvements in sPGA, demonstrating proof of concept in chronic plaque psoriasis.
Discrete Curvature Theories and Applications
Sun, Xiang
2016-08-25
Discrete Di erential Geometry (DDG) concerns discrete counterparts of notions and methods in di erential geometry. This thesis deals with a core subject in DDG, discrete curvature theories on various types of polyhedral surfaces that are practically important for free-form architecture, sunlight-redirecting shading systems, and face recognition. Modeled as polyhedral surfaces, the shapes of free-form structures may have to satisfy di erent geometric or physical constraints. We study a combination of geometry and physics { the discrete surfaces that can stand on their own, as well as having proper shapes for the manufacture. These proper shapes, known as circular and conical meshes, are closely related to discrete principal curvatures. We study curvature theories that make such surfaces possible. Shading systems of freeform building skins are new types of energy-saving structures that can re-direct the sunlight. From these systems, discrete line congruences across polyhedral surfaces can be abstracted. We develop a new curvature theory for polyhedral surfaces equipped with normal congruences { a particular type of congruences de ned by linear interpolation of vertex normals. The main results are a discussion of various de nitions of normality, a detailed study of the geometry of such congruences, and a concept of curvatures and shape operators associated with the faces of a triangle mesh. These curvatures are compatible with both normal congruences and the Steiner formula. In addition to architecture, we consider the role of discrete curvatures in face recognition. We use geometric measure theory to introduce the notion of asymptotic cones associated with a singular subspace of a Riemannian manifold, which is an extension of the classical notion of asymptotic directions. We get a simple expression of these cones for polyhedral surfaces, as well as convergence and approximation theorems. We use the asymptotic cones as facial descriptors and demonstrate the
Stable convergence and stable limit theorems
Häusler, Erich
2015-01-01
The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...
Foundations of the probabilistic mechanics of discrete media
Axelrad, D R
1984-01-01
This latest volume in the Foundations & Philosophy of Science & Technology series provides an account of probabilistic functional analysis and shows its applicability in the formulation of the behaviour of discrete media with the inclusion of microstructural effects. Although quantum mechanics have long been recognized as a stochastic theory, the introduction of probabilistic concepts and principles to classical mechanics has in general not been attempted. In this study the author takes the view that the significant field quantities of a discrete medium are random variables or functions of s
Comparing Fr\\'echet and positive stable laws
Simon, Thomas
2013-01-01
Let ${\\bf L}$ be the unit exponential random variable and ${\\bf Z}_\\alpha$ the standard positive $\\alpha$-stable random variable. We prove that $\\{(1-\\alpha) \\alpha^{\\gamma_\\alpha} {\\bf Z}_\\alpha^{-\\gamma_\\alpha}, 0< \\alpha
Analysis of Discrete Mittag - Leffler Functions
Directory of Open Access Journals (Sweden)
N. Shobanadevi
2015-03-01
Full Text Available Discrete Mittag - Leffler functions play a major role in the development of the theory of discrete fractional calculus. In the present article, we analyze qualitative properties of discrete Mittag - Leffler functions and establish sufficient conditions for convergence, oscillation and summability of the infinite series associated with discrete Mittag - Leffler functions.
Chaos in discrete fractional difference equations
Indian Academy of Sciences (India)
2016-09-07
Sep 7, 2016 ... logistics map and discrete sine map [14,15]. In this paper, we analyse numerically the chaotic behaviour of three maps viz., discrete tent map, discrete 2x(mod1) map and discrete Gauss map. Study of these maps is important as they are standard one-dimensional maps, well known to show characteristic ...
Foundations of a discrete physics
International Nuclear Information System (INIS)
McGoveran, D.; Noyes, P.
1988-01-01
Starting from the principles of finiteness, discreteness, finite computability and absolute nonuniqueness, we develop the ordering operator calculus, a strictly constructive mathematical system having the empirical properties required by quantum mechanical and special relativistic phenomena. We show how to construct discrete distance functions, and both rectangular and spherical coordinate systems(with a discrete version of ''π''). The richest discrete space constructible without a preferred axis and preserving translational and rotational invariance is shown to be a discrete 3-space with the usual symmetries. We introduce a local ordering parameter with local (proper) time-like properties and universal ordering parameters with global (cosmological) time-like properties. Constructed ''attribute velocities'' connect ensembles with attributes that are invariant as the appropriate time-like parameter increases. For each such attribute, we show how to construct attribute velocities which must satisfy the '' relativistic Doppler shift'' and the ''relativistic velocity composition law,'' as well as the Lorentz transformations. By construction, these velocities have finite maximum and minimum values. In the space of all attributes, the minimum of these maximum velocities will predominate in all multiple attribute computations, and hence can be identified as a fundamental limiting velocity, General commutation relations are constructed which under the physical interpretation are shown to reduce to the usual quantum mechanical commutation relations. 50 refs., 18 figs
Degree distribution in discrete case
International Nuclear Information System (INIS)
Wang, Li-Na; Chen, Bin; Yan, Zai-Zai
2011-01-01
Vertex degree of many network models and real-life networks is limited to non-negative integer. By means of measure and integral, the relation of the degree distribution and the cumulative degree distribution in discrete case is analyzed. The degree distribution, obtained by the differential of its cumulative, is only suitable for continuous case or discrete case with constant degree change. When degree change is not a constant but proportional to degree itself, power-law degree distribution and its cumulative have the same exponent and the mean value is finite for power-law exponent greater than 1. -- Highlights: → Degree change is the crux for using the cumulative degree distribution method. → It suits for discrete case with constant degree change. → If degree change is proportional to degree, power-law degree distribution and its cumulative have the same exponent. → In addition, the mean value is finite for power-law exponent greater than 1.
Geometry of discrete quantum computing
Hanson, Andrew J.; Ortiz, Gerardo; Sabry, Amr; Tai, Yu-Tsung
2013-05-01
Conventional quantum computing entails a geometry based on the description of an n-qubit state using 2n infinite precision complex numbers denoting a vector in a Hilbert space. Such numbers are in general uncomputable using any real-world resources, and, if we have the idea of physical law as some kind of computational algorithm of the universe, we would be compelled to alter our descriptions of physics to be consistent with computable numbers. Our purpose here is to examine the geometric implications of using finite fields Fp and finite complexified fields \\mathbf {F}_{p^2} (based on primes p congruent to 3 (mod4)) as the basis for computations in a theory of discrete quantum computing, which would therefore become a computable theory. Because the states of a discrete n-qubit system are in principle enumerable, we are able to determine the proportions of entangled and unentangled states. In particular, we extend the Hopf fibration that defines the irreducible state space of conventional continuous n-qubit theories (which is the complex projective space \\mathbf {CP}^{2^{n}-1}) to an analogous discrete geometry in which the Hopf circle for any n is found to be a discrete set of p + 1 points. The tally of unit-length n-qubit states is given, and reduced via the generalized Hopf fibration to \\mathbf {DCP}^{2^{n}-1}, the discrete analogue of the complex projective space, which has p^{2^{n}-1} (p-1)\\,\\prod _{k=1}^{n-1} ( p^{2^{k}}+1) irreducible states. Using a measure of entanglement, the purity, we explore the entanglement features of discrete quantum states and find that the n-qubit states based on the complexified field \\mathbf {F}_{p^2} have pn(p - 1)n unentangled states (the product of the tally for a single qubit) with purity 1, and they have pn + 1(p - 1)(p + 1)n - 1 maximally entangled states with purity zero.
Heuristic Optimization for the Discrete Virtual Power Plant Dispatch Problem
DEFF Research Database (Denmark)
Petersen, Mette Kirschmeyer; Hansen, Lars Henrik; Bendtsen, Jan Dimon
2014-01-01
We consider a Virtual Power Plant, which is given the task of dispatching a fluctuating power supply to a portfolio of flexible consumers. The flexible consumers are modeled as discrete batch processes, and the associated optimization problem is denoted the Discrete Virtual Power Plant Dispatch...... Problem. First NP-completeness of the Discrete Virtual Power Plant Dispatch Problem is proved formally. We then proceed to develop tailored versions of the meta-heuristic algorithms Hill Climber and Greedy Randomized Adaptive Search Procedure (GRASP). The algorithms are tuned and tested on portfolios...... of varying sizes. We find that all the tailored algorithms perform satisfactorily in the sense that they are able to find sub-optimal, but usable, solutions to very large problems (on the order of 10 5 units) at computation times on the scale of just 10 seconds, which is far beyond the capabilities...
National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...
Choice certainty in Discrete Choice Experiments
DEFF Research Database (Denmark)
Uggeldahl, Kennet Christian; Jacobsen, Catrine; Lundhede, Thomas
2016-01-01
In this study, we conduct a Discrete Choice Experiment (DCE) using eye tracking technology to investigate if eye movements during the completion of choice sets reveal information about respondents’ choice certainty. We hypothesise that the number of times that respondents shift their visual...... attention between the alternatives in a choice set reflects their stated choice certainty. Based on one of the largest samples of eye tracking data in a DCE to date, we find evidence in favor of our hypothesis. We also link eye tracking observations to model-based choice certainty through parameterization...... of the scale function in a random parameters logit model. We find that choices characterized by more frequent gaze shifting do indeed exhibit a higher degree of error variance, however, this effects is insignificant once response time is controlled for. Overall, findings suggest that eye tracking can provide...
Plante, Jean-Sébastien; Devita, Lauren M.; Dubowsky, Steven
2007-04-01
Fundamental studies of Dielectric Elastomer Actuators (DEAs) using viscoelastic materials such as VHB 4905/4910 from 3M showed significant advantages at high stretch rates. The film's viscous forces increase actuator life and the short power-on times minimize energy losses through current leakage. This paper presents a design paradigm that exploits these fundamental properties of DEAs called discrete actuation. Discrete actuation uses DEAs at high stretch rates to change the states of robotic or mechatronic systems in discrete steps. Each state of the system is stable and can be maintained without actuator power. Discrete actuation can be used in robotic and mechatronic applications such as manipulation and locomotion. The resolution of such systems increases with the number of discrete states, 10 to 100 being sufficient for many applications. An MRI-guided needle positioning device for cancer treatments and a space exploration robot using hopping for locomotion are presented as examples of this concept.
Path integrals as discrete sums
Bitar, Khalil; Khuri, N. N.; Ren, H. C.
1991-08-01
We present a new formulation of Feynman's path integral, based on Voronin's theorems on the universality of the Riemann zeta function. The result is a discrete sum over ``paths,'' each given by a zeta function. A new measure which leads to the correct quantum mechanics is explicitly given.
Multiscale expansions in discrete world
Indian Academy of Sciences (India)
Multiscale expansions in discrete world. ÖMER ÜNSAL, FILIZ TASCAN. ∗ and MEHMET NACI ÖZER. Eskisehir Osmangazi University, Art-Science Faculty, Department of Mathematics and Computer. Sciences, Eskisehir-Türkiye. ∗. Corresponding author. E-mail: ftascan@ogu.edu.tr. MS received 12 April 2013; accepted 16 ...
The remarkable discreteness of being
Indian Academy of Sciences (India)
2014-03-15
Mar 15, 2014 ... ... examples where these facts play, or could play, important roles: the spatial distribution of species, the structuring of biodiversity and the. (Darwinian) evolution of altruistic behaviour. [Houchmandzadeh B 2014 The remarkable discreteness of being. J. Biosci. 39 249–258] DOI 10.1007/s12038-013-9350-7.
Discrete tomography in neutron radiography
International Nuclear Information System (INIS)
Kuba, Attila; Rodek, Lajos; Kiss, Zoltan; Rusko, Laszlo; Nagy, Antal; Balasko, Marton
2005-01-01
Discrete tomography (DT) is an imaging technique for reconstructing discrete images from their projections using the knowledge that the object to be reconstructed contains only a few homogeneous materials characterized by known discrete absorption values. One of the main reasons for applying DT is that we will hopefully require relatively few projections. Using discreteness and some a priori information (such as an approximate shape of the object) we can apply two DT methods in neutron imaging by reducing the problem to an optimization task. The first method is a special one because it is only suitable if the object is composed of cylinders and sphere shapes. The second method is a general one in the sense that it can be used for reconstructing objects of any shape. Software was developed and physical experiments performed in order to investigate the effects of several reconstruction parameters: the number of projections, noise levels, and complexity of the object to be reconstructed. We give a summary of the experimental results and make a comparison of the results obtained using a classical reconstruction technique (FBP). The programs we developed are available in our DT reconstruction program package DIRECT
Intelligent discrete particle swarm optimization for multiprocessor task scheduling problem
Directory of Open Access Journals (Sweden)
S Sarathambekai
2017-03-01
Full Text Available Discrete particle swarm optimization is one of the most recently developed population-based meta-heuristic optimization algorithm in swarm intelligence that can be used in any discrete optimization problems. This article presents a discrete particle swarm optimization algorithm to efficiently schedule the tasks in the heterogeneous multiprocessor systems. All the optimization algorithms share a common algorithmic step, namely population initialization. It plays a significant role because it can affect the convergence speed and also the quality of the final solution. The random initialization is the most commonly used method in majority of the evolutionary algorithms to generate solutions in the initial population. The initial good quality solutions can facilitate the algorithm to locate the optimal solution or else it may prevent the algorithm from finding the optimal solution. Intelligence should be incorporated to generate the initial population in order to avoid the premature convergence. This article presents a discrete particle swarm optimization algorithm, which incorporates opposition-based technique to generate initial population and greedy algorithm to balance the load of the processors. Make span, flow time, and reliability cost are three different measures used to evaluate the efficiency of the proposed discrete particle swarm optimization algorithm for scheduling independent tasks in distributed systems. Computational simulations are done based on a set of benchmark instances to assess the performance of the proposed algorithm.
Time-Discrete Higher-Order ALE Formulations: Stability
Bonito, Andrea
2013-01-01
Arbitrary Lagrangian Eulerian (ALE) formulations deal with PDEs on deformable domains upon extending the domain velocity from the boundary into the bulk with the purpose of keeping mesh regularity. This arbitrary extension has no effect on the stability of the PDE but may influence that of a discrete scheme. We examine this critical issue for higher-order time stepping without space discretization. We propose time-discrete discontinuous Galerkin (dG) numerical schemes of any order for a time-dependent advection-diffusion-model problem in moving domains, and study their stability properties. The analysis hinges on the validity of the Reynold\\'s identity for dG. Exploiting the variational structure and assuming exact integration, we prove that our conservative and nonconservative dG schemes are equivalent and unconditionally stable. The same results remain true for piecewise polynomial ALE maps of any degree and suitable quadrature that guarantees the validity of the Reynold\\'s identity. This approach generalizes the so-called geometric conservation law to higher-order methods. We also prove that simpler Runge-Kutta-Radau methods of any order are conditionally stable, that is, subject to a mild ALE constraint on the time steps. Numerical experiments corroborate and complement our theoretical results. © 2013 Society for Industrial and Applied Mathematics.
Discrete compactons: some exact results
International Nuclear Information System (INIS)
Kevrekidis, P G; Konotop, V V; Bishop, A R; Takeno, S
2002-01-01
In this letter, we use the method of constructing exact solutions on lattices proposed by Kinnersley and described in Schmidt (1979 Phys. Rev. B 20 4397), to obtain exact compacton solutions in discrete models. We examine the linear stability of such solutions, both for the bright compacton and for the dark compacton cases. We focus on a 'quantization condition' that the width of the profile should satisfy. We also use this quantization condition to examine the possibility of compact coherent structures travelling in discrete settings. Our results are obtained for sinusoidal profiles and then generalized to elliptic functions of arbitrary modulus. The possibility of multi-compacton solutions is considered. (letter to the editor)
Discrete mathematics using a computer
Hall, Cordelia
2000-01-01
Several areas of mathematics find application throughout computer science, and all students of computer science need a practical working understanding of them. These core subjects are centred on logic, sets, recursion, induction, relations and functions. The material is often called discrete mathematics, to distinguish it from the traditional topics of continuous mathematics such as integration and differential equations. The central theme of this book is the connection between computing and discrete mathematics. This connection is useful in both directions: • Mathematics is used in many branches of computer science, in applica tions including program specification, datastructures,design and analysis of algorithms, database systems, hardware design, reasoning about the correctness of implementations, and much more; • Computers can help to make the mathematics easier to learn and use, by making mathematical terms executable, making abstract concepts more concrete, and through the use of software tools su...
Quantum chaos on discrete graphs
Energy Technology Data Exchange (ETDEWEB)
Smilansky, Uzy [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, Cambridge CB3 0EH (United Kingdom)
2007-07-06
Adapting a method developed for the study of quantum chaos on quantum (metric) graphs (Kottos and Smilansky 1997 Phys. Rev. Lett. 79 4794, Kottos and Smilansky 1999 Ann. Phys., NY 274 76), spectral {zeta} functions and trace formulae for discrete Laplacians on graphs are derived. This is achieved by expressing the spectral secular equation in terms of the periodic orbits of the graph and obtaining functions which belong to the class of {zeta} functions proposed originally by Ihara (1966 J. Mat. Soc. Japan 18 219) and expanded by subsequent authors (Stark and Terras 1996 Adv. Math. 121 124, Kotani and Sunada 2000 J. Math. Sci. Univ. Tokyo 7 7). Finally, a model of 'classical dynamics' on the discrete graph is proposed. It is analogous to the corresponding classical dynamics derived for quantum graphs (Kottos and Smilansky 1997 Phys. Rev. Lett. 79 4794, Kottos and Smilansky 1999 Ann. Phys., NY 274 76). (fast track communication)
Discrete symmetries in the MSSM
Energy Technology Data Exchange (ETDEWEB)
Schieren, Roland
2010-12-02
The use of discrete symmetries, especially abelian ones, in physics beyond the standard model of particle physics is discussed. A method is developed how a general, abelian, discrete symmetry can be obtained via spontaneous symmetry breaking. In addition, anomalies are treated in the path integral approach with special attention to anomaly cancellation via the Green-Schwarz mechanism. All this is applied to the minimal supersymmetric standard model. A unique Z{sup R}{sub 4} symmetry is discovered which solves the {mu}-problem as well as problems with proton decay and allows to embed the standard model gauge group into a simple group, i.e. the Z{sup R}{sub 4} is compatible with grand unification. Also the flavor problem in the context of minimal flavor violation is addressed. Finally, a string theory model is presented which exhibits the mentioned Z{sup R}{sub 4} symmetry and other desirable features. (orig.)
Applied geometry and discrete mathematics
Sturm; Gritzmann, Peter; Sturmfels, Bernd
1991-01-01
This volume, published jointly with the Association for Computing Machinery, comprises a collection of research articles celebrating the occasion of Victor Klee's sixty-fifth birthday in September 1990. During his long career, Klee has made contributions to a wide variety of areas, such as discrete and computational geometry, convexity, combinatorics, graph theory, functional analysis, mathematical programming and optimization, and theoretical computer science. In addition, Klee made important contributions to mathematics education, mathematical methods in economics and the decision sciences, applications of discrete mathematics in the biological and social sciences, and the transfer of knowledge from applied mathematics to industry. In honor of Klee's achievements, this volume presents more than forty papers on topics related to Klee's research. While the majority of the papers are research articles, a number of survey articles are also included. Mirroring the breadth of Klee's mathematical contributions, th...
Dark energy from discrete spacetime.
Trout, Aaron D
2013-01-01
Dark energy accounts for most of the matter-energy content of our universe, yet current theories of its origin rely on radical physical assumptions such as the holographic principle or controversial anthropic arguments. We give a better motivated explanation for dark energy, claiming that it arises from a small negative scalar-curvature present even in empty spacetime. The vacuum has this curvature because spacetime is fundamentally discrete and there are more ways for a discrete geometry to have negative curvature than positive. We explicitly compute this effect using a variant of the well known dynamical-triangulations (DT) model for quantum gravity. Our model predicts a time-varying non-zero cosmological constant with a current value, [Formula: see text] in natural units, in agreement with observation. This calculation is made possible by a novel characterization of the possible DT action values combined with numerical evidence concerning their degeneracies.
Duality for discrete integrable systems
International Nuclear Information System (INIS)
Quispel, G R W; Capel, H W; Roberts, J A G
2005-01-01
A new class of discrete dynamical systems is introduced via a duality relation for discrete dynamical systems with a number of explicitly known integrals. The dual equation can be defined via the difference of an arbitrary linear combination of integrals and its upshifted version. We give an example of an integrable mapping with two parameters and four integrals leading to a (four-dimensional) dual mapping with four parameters and two integrals. We also consider a more general class of higher-dimensional mappings arising via a travelling-wave reduction from the (integrable) MKdV partial-difference equation. By differencing the trace of the monodromy matrix we obtain a class of novel dual mappings which is shown to be integrable as level-set-dependent versions of the original ones
Disease Extinction Versus Persistence in Discrete-Time Epidemic Models.
van den Driessche, P; Yakubu, Abdul-Aziz
2018-04-12
We focus on discrete-time infectious disease models in populations that are governed by constant, geometric, Beverton-Holt or Ricker demographic equations, and give a method for computing the basic reproduction number, [Formula: see text]. When [Formula: see text] and the demographic population dynamics are asymptotically constant or under geometric growth (non-oscillatory), we prove global asymptotic stability of the disease-free equilibrium of the disease models. Under the same demographic assumption, when [Formula: see text], we prove uniform persistence of the disease. We apply our theoretical results to specific discrete-time epidemic models that are formulated for SEIR infections, cholera in humans and anthrax in animals. Our simulations show that a unique endemic equilibrium of each of the three specific disease models is asymptotically stable whenever [Formula: see text].
Direct output feedback control of discrete-time systems
International Nuclear Information System (INIS)
Lin, C.C.; Chung, L.L.; Lu, K.H.
1993-01-01
An optimal direct output feedback control algorithm is developed for discrete-time systems with the consideration of time delay in control force action. Optimal constant output feedback gains are obtained through variational process such that certain prescribed quadratic performance index is minimized. Discrete-time control forces are then calculated from the multiplication of output measurements by these pre-calculated feedback gains. According to the proposed algorithm, structural system is assured to remain stable even in the presence of time delay. The number of sensors and controllers may be very small as compared with the dimension of states. Numerical results show that direct velocity feedback control is more sensitive to time delay than state feedback but, is still quite effective in reducing the dynamic responses under earthquake excitation. (author)
Students' Misconceptions about Random Variables
Kachapova, Farida; Kachapov, Ilias
2012-01-01
This article describes some misconceptions about random variables and related counter-examples, and makes suggestions about teaching initial topics on random variables in general form instead of doing it separately for discrete and continuous cases. The focus is on post-calculus probability courses. (Contains 2 figures.)
Discrete fractional solutions of a Legendre equation
Yılmazer, Resat
2018-01-01
One of the most popular research interests of science and engineering is the fractional calculus theory in recent times. Discrete fractional calculus has also an important position in fractional calculus. In this work, we acquire new discrete fractional solutions of the homogeneous and non homogeneous Legendre differential equation by using discrete fractional nabla operator.
High-Order Entropy Stable Formulations for Computational Fluid Dynamics
Carpenter, Mark H.; Fisher, Travis C.
2013-01-01
A systematic approach is presented for developing entropy stable (SS) formulations of any order for the Navier-Stokes equations. These SS formulations discretely conserve mass, momentum, energy and satisfy a mathematical entropy inequality. They are valid for smooth as well as discontinuous flows provided sufficient dissipation is added at shocks and discontinuities. Entropy stable formulations exist for all diagonal norm, summation-by-parts (SBP) operators, including all centered finite-difference operators, Legendre collocation finite-element operators, and certain finite-volume operators. Examples are presented using various entropy stable formulations that demonstrate the current state-of-the-art of these schemes.
On equivalence of discrete-discrete and continuum-discrete design sensitivity analysis
Choi, Kyung K.; Twu, Sung-Ling
1989-01-01
Developments in design sensitivity analysis (DSA) method have been made using two fundamentally different approaches as shown. In the first approach, a discretized structural finite element model is used to carry out DSA. There are three different methods in the discrete DSA approach: finite difference, semi-analytical, and analytical methods. The finite difference method is a popular one due to its simplicity, but a serious shortcoming of the method is the uncertainty in the choice of a perturbation step size of design variables. In the semi-analytical method, the derivatives of stiffness matrix is computed by finite differences, whereas in the analytical method, the derivatives are obtained analytically. For the shape design variable, computation of analytical derivative of stiffness matrix is quite costly. Because of this, the semi-analytical method is a popular choice in discrete shape DSA approach. However, recently, Barthelemy and Haftka presented that the semi-analytical method can have serious accuracy problems for shape design variables in structures modeled by beam, plate, truss, frame, and solid elements. They found that accuracy problems occur even for a simple cantilever beam. In the second approach, a continuum model of the structure is used to carry out DSA.
Stable isotopes labelled compounds
International Nuclear Information System (INIS)
1982-09-01
The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme
Steeneveld, G.J.
2012-01-01
Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The
Indian Academy of Sciences (India)
IAS Admin
After Maynard-Smith and Price [1] mathematically derived why a given behaviour or strategy was adopted by a certain proportion of the population at a given time, it was shown that a strategy which is currently stable in a population need not be stable in evolutionary time (across generations). Additionally it was sug-.
On The Roman Domination Stable Graphs
Directory of Open Access Journals (Sweden)
Hajian Majid
2017-11-01
Full Text Available A Roman dominating function (or just RDF on a graph G = (V,E is a function f : V → {0, 1, 2} satisfying the condition that every vertex u for which f(u = 0 is adjacent to at least one vertex v for which f(v = 2. The weight of an RDF f is the value f(V (G = Pu2V (G f(u. The Roman domination number of a graph G, denoted by R(G, is the minimum weight of a Roman dominating function on G. A graph G is Roman domination stable if the Roman domination number of G remains unchanged under removal of any vertex. In this paper we present upper bounds for the Roman domination number in the class of Roman domination stable graphs, improving bounds posed in [V. Samodivkin, Roman domination in graphs: the class RUV R, Discrete Math. Algorithms Appl. 8 (2016 1650049].
OCT Amplitude and Speckle Statistics of Discrete Random Media
Almasian, Mitra; van Leeuwen, Ton G.; Faber, Dirk J.
2017-01-01
Speckle, amplitude fluctuations in optical coherence tomography (OCT) images, contains information on sub-resolution structural properties of the imaged sample. Speckle statistics could therefore be utilized in the characterization of biological tissues. However, a rigorous theoretical framework
Probability Distributions of Minkowski Distances between Discrete Random Variables.
Schroger, Erich; And Others
1993-01-01
Minkowski distances are used to indicate similarity of two vectors in an N-dimensional space. How to compute the probability function, the expectation, and the variance for Minkowski distances and the special cases City-block distance and Euclidean distance. Critical values for tests of significance are presented in tables. (SLD)
Multiple Scattering of Waves in Discrete Random Media.
1987-12-31
between the current-volt- and oceanographic engineering from the Univer- age characteristic of a semiconductor heterojunction and the variation in sity...jk - <uj>j <uk>kJ drjdrk Sno I <! u 2>J drj. (19) The second term in the above equation, which is proportional to no , is the ordinary single
Discrete geometric structures for architecture
Pottmann, Helmut
2010-06-13
The emergence of freeform structures in contemporary architecture raises numerous challenging research problems, most of which are related to the actual fabrication and are a rich source of research topics in geometry and geometric computing. The talk will provide an overview of recent progress in this field, with a particular focus on discrete geometric structures. Most of these result from practical requirements on segmenting a freeform shape into planar panels and on the physical realization of supporting beams and nodes. A study of quadrilateral meshes with planar faces reveals beautiful relations to discrete differential geometry. In particular, we discuss meshes which discretize the network of principal curvature lines. Conical meshes are among these meshes; they possess conical offset meshes at a constant face/face distance, which in turn leads to a supporting beam layout with so-called torsion free nodes. This work can be generalized to a variety of multilayer structures and laid the ground for an adapted curvature theory for these meshes. There are also efforts on segmenting surfaces into planar hexagonal panels. Though these are less constrained than planar quadrilateral panels, this problem is still waiting for an elegant solution. Inspired by freeform designs in architecture which involve circles and spheres, we present a new kind of triangle mesh whose faces\\' in-circles form a packing, i.e., the in-circles of two triangles with a common edge have the same contact point on that edge. These "circle packing (CP) meshes" exhibit an aesthetic balance of shape and size of their faces. They are closely tied to sphere packings on surfaces and to various remarkable structures and patterns which are of interest in art, architecture, and design. CP meshes constitute a new link between architectural freeform design and computational conformal geometry. Recently, certain timber structures motivated us to study discrete patterns of geodesics on surfaces. This
Radiative transfer on discrete spaces
Preisendorfer, Rudolph W; Stark, M; Ulam, S
1965-01-01
Pure and Applied Mathematics, Volume 74: Radiative Transfer on Discrete Spaces presents the geometrical structure of natural light fields. This book describes in detail with mathematical precision the radiometric interactions of light-scattering media in terms of a few well established principles.Organized into four parts encompassing 15 chapters, this volume begins with an overview of the derivations of the practical formulas and the arrangement of formulas leading to numerical solution procedures of radiative transfer problems in plane-parallel media. This text then constructs radiative tran
Normal modified stable processes
DEFF Research Database (Denmark)
Barndorff-Nielsen, Ole Eiler; Shephard, N.
2002-01-01
This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...... Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process...
Applications of stable isotopes
International Nuclear Information System (INIS)
Letolle, R.; Mariotti, A.; Bariac, T.
1991-06-01
This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe
Zhang, Meirong; Saberi, Ali; Stoorvogel, Antonie Arij
2015-01-01
This paper studies the synchronization problem for a network of identical discrete-time agents with unknown, nonuniform constant input delays. The agents are at most critically stable and non-introspective (i.e. the agents have no access to their own states or outputs). There exists full state
On discrete cosine transform | Zhou | Nigerian Journal of ...
African Journals Online (AJOL)
A new type of discrete cosine transform is proposed and its orthogonality is proved. Finally, we propose a generalized discrete W transform with three parameters, and prove its orthogonality for some new cases. Keywords: Discrete Fourier transform, discrete sine transform, discrete cosine transform, discrete W transform
National Research Council Canada - National Science Library
Adler, Robert
1997-01-01
We describe how to take a stable, ARMA, time series through the various stages of model identification, parameter estimation, and diagnostic checking, and accompany the discussion with a goodly number...
Statistics of primordial density perturbations from discrete seed masses
Scherrer, Robert J.; Bertschinger, Edmund
1991-01-01
The statistics of density perturbations for general distributions of seed masses with arbitrary matter accretion is examined. Formal expressions for the power spectrum, the N-point correlation functions, and the density distribution function are derived. These results are applied to the case of uncorrelated seed masses, and power spectra are derived for accretion of both hot and cold dark matter plus baryons. The reduced moments (cumulants) of the density distribution are computed and used to obtain a series expansion for the density distribution function. Analytic results are obtained for the density distribution function in the case of a distribution of seed masses with a spherical top-hat accretion pattern. More generally, the formalism makes it possible to give a complete characterization of the statistical properties of any random field generated from a discrete linear superposition of kernels. In particular, the results can be applied to density fields derived by smoothing a discrete set of points with a window function.
Filtser, Omrit; Katz, Matthew J.
2015-01-01
We introduce the discrete Fr\\'echet gap and its variants as an alternative measure of similarity between polygonal curves. We believe that for some applications the new measure (and its variants) may better reflect our intuitive notion of similarity than the discrete Fr\\'echet distance (and its variants), since the latter measure is indifferent to (matched) pairs of points that are relatively close to each other. Referring to the frogs analogy by which the discrete Fr\\'echet distance is often...
Discrete calculus methods for counting
Mariconda, Carlo
2016-01-01
This book provides an introduction to combinatorics, finite calculus, formal series, recurrences, and approximations of sums. Readers will find not only coverage of the basic elements of the subjects but also deep insights into a range of less common topics rarely considered within a single book, such as counting with occupancy constraints, a clear distinction between algebraic and analytical properties of formal power series, an introduction to discrete dynamical systems with a thorough description of Sarkovskii’s theorem, symbolic calculus, and a complete description of the Euler-Maclaurin formulas and their applications. Although several books touch on one or more of these aspects, precious few cover all of them. The authors, both pure mathematicians, have attempted to develop methods that will allow the student to formulate a given problem in a precise mathematical framework. The aim is to equip readers with a sound strategy for classifying and solving problems by pursuing a mathematically rigorous yet ...
Quantum evolution by discrete measurements
International Nuclear Information System (INIS)
Roa, L; Guevara, M L Ladron de; Delgado, A; Olivares-RenterIa, G; Klimov, A B
2007-01-01
In this article we review two ways of driving a quantum system to a known pure state via a sequence discrete of von Neumann measurements. The first of them assumes that the initial state of the system is unknown, and the evolution is attained only with the help of two non-commuting observables. For this method, the overall success probability is maximized when the eigentstates of the involved observables constitute mutually unbiased bases. The second method assumes the initial state is known and it uses N observables which are consecutively measured to make the state of the system approach the target state. The probability of success of this procedure converges to 1 as the number of observables increases
Quantum evolution by discrete measurements
Energy Technology Data Exchange (ETDEWEB)
Roa, L [Center for Quantum Optics and Quantum Information, Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Guevara, M L Ladron de [Departamento de Fisica, Universidad Catolica del Norte, Casilla 1280, Antofagasta (Chile); Delgado, A [Center for Quantum Optics and Quantum Information, Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Olivares-RenterIa, G [Center for Quantum Optics and Quantum Information, Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Klimov, A B [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, 44420 Guadalajara, Jalisco (Mexico)
2007-10-15
In this article we review two ways of driving a quantum system to a known pure state via a sequence discrete of von Neumann measurements. The first of them assumes that the initial state of the system is unknown, and the evolution is attained only with the help of two non-commuting observables. For this method, the overall success probability is maximized when the eigentstates of the involved observables constitute mutually unbiased bases. The second method assumes the initial state is known and it uses N observables which are consecutively measured to make the state of the system approach the target state. The probability of success of this procedure converges to 1 as the number of observables increases.
Modeling discrete competitive facility location
Karakitsiou, Athanasia
2015-01-01
This book presents an up-to-date review of modeling and optimization approaches for location problems along with a new bi-level programming methodology which captures the effect of competition of both producers and customers on facility location decisions. While many optimization approaches simplify location problems by assuming decision making in isolation, this monograph focuses on models which take into account the competitive environment in which such decisions are made. New insights in modeling, algorithmic and theoretical possibilities are opened by this approach and new applications are possible. Competition on equal term plus competition between market leader and followers are considered in this study, consequently bi-level optimization methodology is emphasized and further developed. This book provides insights regarding modeling complexity and algorithmic approaches to discrete competitive location problems. In traditional location modeling, assignment of customer demands to supply sources are made ...
Multigrid methods for isogeometric discretization.
Gahalaut, K P S; Kraus, J K; Tomar, S K
2013-01-01
We present (geometric) multigrid methods for isogeometric discretization of scalar second order elliptic problems. The smoothing property of the relaxation method, and the approximation property of the intergrid transfer operators are analyzed. These properties, when used in the framework of classical multigrid theory, imply uniform convergence of two-grid and multigrid methods. Supporting numerical results are provided for the smoothing property, the approximation property, convergence factor and iterations count for V -, W - and F -cycles, and the linear dependence of V -cycle convergence on the smoothing steps. For two dimensions, numerical results include the problems with variable coefficients, simple multi-patch geometry, a quarter annulus, and the dependence of convergence behavior on refinement levels [Formula: see text], whereas for three dimensions, only the constant coefficient problem in a unit cube is considered. The numerical results are complete up to polynomial order [Formula: see text], and for [Formula: see text] and [Formula: see text] smoothness.
Discrete modelling of drapery systems
Thoeni, Klaus; Giacomini, Anna
2016-04-01
Drapery systems are an efficient and cost-effective measure in preventing and controlling rockfall hazards on rock slopes. The simplest form consists of a row of ground anchors along the top of the slope connected to a horizontal support cable from which a wire mesh is suspended down the face of the slope. Such systems are generally referred to as simple or unsecured draperies (Badger and Duffy 2012). Variations such as secured draperies, where a pattern of ground anchors is incorporated within the field of the mesh, and hybrid systems, where the upper part of an unsecured drapery is elevated to intercept rockfalls originating upslope of the installation, are becoming more and more popular. This work presents a discrete element framework for simulation of unsecured drapery systems and its variations. The numerical model is based on the classical discrete element method (DEM) and implemented into the open-source framework YADE (Šmilauer et al., 2010). The model takes all relevant interactions between block, drapery and slope into account (Thoeni et al., 2014) and was calibrated and validated based on full-scale experiments (Giacomini et al., 2012).The block is modelled as a rigid clump made of spherical particles which allows any shape to be approximated. The drapery is represented by a set of spherical particle with remote interactions. The behaviour of the remote interactions is governed by the constitutive behaviour of the wire and generally corresponds to a piecewise linear stress-strain relation (Thoeni et al., 2013). The same concept is used to model wire ropes. The rock slope is represented by rigid triangular elements where material properties (e.g., normal coefficient of restitution, friction angle) are assigned to each triangle. The capabilities of the developed model to simulate drapery systems and estimate the residual hazard involved with such systems is shown. References Badger, T.C., Duffy, J.D. (2012) Drapery systems. In: Turner, A.K., Schuster R
Discrete stochastic processes and applications
Collet, Jean-François
2018-01-01
This unique text for beginning graduate students gives a self-contained introduction to the mathematical properties of stochastics and presents their applications to Markov processes, coding theory, population dynamics, and search engine design. The book is ideal for a newly designed course in an introduction to probability and information theory. Prerequisites include working knowledge of linear algebra, calculus, and probability theory. The first part of the text focuses on the rigorous theory of Markov processes on countable spaces (Markov chains) and provides the basis to developing solid probabilistic intuition without the need for a course in measure theory. The approach taken is gradual beginning with the case of discrete time and moving on to that of continuous time. The second part of this text is more applied; its core introduces various uses of convexity in probability and presents a nice treatment of entropy.
Localized solutions for a nonlocal discrete NLS equation
Energy Technology Data Exchange (ETDEWEB)
Ben, Roberto I. [Instituto de Desarrollo Humano, Universidad Nacional de General Sarmiento, J.M. Gutiérrez 1150, 1613 Los Polvorines (Argentina); Cisneros Ake, Luís [Department of Mathematics, ESFM, Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos Edificio 9, 07738 México D.F. (Mexico); Minzoni, A.A. [Depto. Matemáticas y Mecánica, I.I.M.A.S.-U.N.A.M., Apdo. Postal 20-726, 01000 México D.F. (Mexico); Panayotaros, Panayotis, E-mail: panos@mym.iimas.unam.mx [Depto. Matemáticas y Mecánica, I.I.M.A.S.-U.N.A.M., Apdo. Postal 20-726, 01000 México D.F. (Mexico)
2015-09-04
We study spatially localized time-periodic solutions of breather type for a cubic discrete NLS equation with a nonlocal nonlinearity that models light propagation in a liquid crystal waveguide array. We show the existence of breather solutions in the limit where both linear and nonlinear intersite couplings vanish, and in the limit where the linear coupling vanishes with arbitrary nonlinear intersite coupling. Breathers of this nonlocal regime exhibit some interesting features that depart from what is seen in the NLS breathers with power nonlinearity. One property we see theoretically is the presence of higher amplitude at interfaces between sites with zero and nonzero amplitude in the vanishing linear coupling limit. A numerical study also suggests the presence of internal modes of orbitally stable localized modes. - Highlights: • Show existence of spatially localized solutions in nonlocal discrete NLS model. • Study spatial properties of localized solutions for arbitrary nonlinear nonlocal coupling. • Present numerical evidence that nonlocality leads to internal modes around stable breathers. • Present theoretical and numerical evidence for amplitude maxima at interfaces.
Stable particle motion in a linear accelerator with solenoid focusing
International Nuclear Information System (INIS)
Wadlinger, E.A.
1979-01-01
The equation governing stable particle motion in a linear ion accelerator containing discrete rf and either discrete or continuous solenoid focusing was derived. It was found for discrete solenoid focusing that: cos μ = (1 + dΔ) cos theta/2 + (lΔ/theta - dtheta/2l - thetaΔd 2 /4l) sin theta/2, Δ = 1/f and l + 2d = βlambda, where μ, theta, f, l, and d are the phase advance per cell, precession angle in the solenoid, focal length of the rf lens, length of the solenoid in one cell, and the drift distance between the center of the rf gap and the effective edge of the solenoid. The relation for a continuous solenoid is found by setting d equal to zero. The boundaries of the stability region for theta vs Δ with fixed l and d are obtained when cos μ =+-1
Calcium stable isotope geochemistry
Energy Technology Data Exchange (ETDEWEB)
Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark
2016-08-01
This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.
Modeling biological tissue growth: discrete to continuum representations.
Hywood, Jack D; Hackett-Jones, Emily J; Landman, Kerry A
2013-09-01
There is much interest in building deterministic continuum models from discrete agent-based models governed by local stochastic rules where an agent represents a biological cell. In developmental biology, cells are able to move and undergo cell division on and within growing tissues. A growing tissue is itself made up of cells which undergo cell division, thereby providing a significant transport mechanism for other cells within it. We develop a discrete agent-based model where domain agents represent tissue cells. Each agent has the ability to undergo a proliferation event whereby an additional domain agent is incorporated into the lattice. If a probability distribution describes the waiting times between proliferation events for an individual agent, then the total length of the domain is a random variable. The average behavior of these stochastically proliferating agents defining the growing lattice is determined in terms of a Fokker-Planck equation, with an advection and diffusion term. The diffusion term differs from the one obtained Landman and Binder [J. Theor. Biol. 259, 541 (2009)] when the rate of growth of the domain is specified, but the choice of agents is random. This discrepancy is reconciled by determining a discrete-time master equation for this process and an associated asymmetric nonexclusion random walk, together with consideration of synchronous and asynchronous updating schemes. All theoretical results are confirmed with numerical simulations. This study furthers our understanding of the relationship between agent-based rules, their implementation, and their associated partial differential equations. Since tissue growth is a significant cellular transport mechanism during embryonic growth, it is important to use the correct partial differential equation description when combining with other cellular functions.
DISCRETE ELEMENT MODELLING OF THE COMPRESSIVE ...
African Journals Online (AJOL)
Discrete element modelling is a numerical method capable of tracking the movement of individual objects within a bulk system and compute the resulting force and deformation as well as other parameters. The Discrete Element Method (DEM) has been used in this study to investigate the deformation of individual particles ...
Geometry and Hamiltonian mechanics on discrete spaces
Talasila, V.; Clemente-Gallardo, J.; Schaft, A.J. van der
2004-01-01
Numerical simulation is often crucial for analysing the behaviour of many complex systems which do not admit analytic solutions. To this end, one either converts a ‘smooth’ model into a discrete (in space and time) model, or models systems directly at a discrete level. The goal of this paper is to
Discrete/PWM Ballast-Resistor Controller
King, Roger J.
1994-01-01
Circuit offers low switching loss and automatic compensation for failure of ballast resistor. Discrete/PWM ballast-resistor controller improved shunt voltage-regulator circuit designed to supply power from high-resistance source to low-impedance bus. Provides both coarse discrete voltage levels (by switching of ballast resistors) and continuous fine control of voltage via pulse-width modulation.
Discrete Fourier analysis of multigrid algorithms
van der Vegt, Jacobus J.W.; Rhebergen, Sander
2011-01-01
The main topic of this report is a detailed discussion of the discrete Fourier multilevel analysis of multigrid algorithms. First, a brief overview of multigrid methods is given for discretizations of both linear and nonlinear partial differential equations. Special attention is given to the
Discretization vs. Rounding Error in Euler's Method
Borges, Carlos F.
2011-01-01
Euler's method for solving initial value problems is an excellent vehicle for observing the relationship between discretization error and rounding error in numerical computation. Reductions in stepsize, in order to decrease discretization error, necessarily increase the number of steps and so introduce additional rounding error. The problem is…
Geometry and Hamiltonian mechanics on discrete spaces
International Nuclear Information System (INIS)
Talasila, V; Clemente-Gallardo, J; Schaft, A J van der
2004-01-01
Numerical simulation is often crucial for analysing the behaviour of many complex systems which do not admit analytic solutions. To this end, one either converts a 'smooth' model into a discrete (in space and time) model, or models systems directly at a discrete level. The goal of this paper is to provide a discrete analogue of differential geometry, and to define on these discrete models a formal discrete Hamiltonian structure-in doing so we try to bring together various fundamental concepts from numerical analysis, differential geometry, algebraic geometry, simplicial homology and classical Hamiltonian mechanics. For example, the concept of a twisted derivation is borrowed from algebraic geometry for developing a discrete calculus. The theory is applied to a nonlinear pendulum and we compare the dynamics obtained through a discrete modelling approach with the dynamics obtained via the usual discretization procedures. Also an example of an energy-conserving algorithm on a simple harmonic oscillator is presented, and its effect on the Poisson structure is discussed
Discrete Riccati equation solutions: Distributed algorithms
Directory of Open Access Journals (Sweden)
D. G. Lainiotis
1996-01-01
Full Text Available In this paper new distributed algorithms for the solution of the discrete Riccati equation are introduced. The algorithms are used to provide robust and computational efficient solutions to the discrete Riccati equation. The proposed distributed algorithms are theoretically interesting and computationally attractive.
Cuspidal discrete series for semisimple symmetric spaces
DEFF Research Database (Denmark)
Andersen, Nils Byrial; Flensted-Jensen, Mogens; Schlichtkrull, Henrik
2012-01-01
We propose a notion of cusp forms on semisimple symmetric spaces. We then study the real hyperbolic spaces in detail, and show that there exists both cuspidal and non-cuspidal discrete series. In particular, we show that all the spherical discrete series are non-cuspidal. (C) 2012 Elsevier Inc. All...
Current Density and Continuity in Discretized Models
Boykin, Timothy B.; Luisier, Mathieu; Klimeck, Gerhard
2010-01-01
Discrete approaches have long been used in numerical modelling of physical systems in both research and teaching. Discrete versions of the Schrodinger equation employing either one or several basis functions per mesh point are often used by senior undergraduates and beginning graduate students in computational physics projects. In studying…
Variance Swap Replication: Discrete or Continuous?
Directory of Open Access Journals (Sweden)
Fabien Le Floc’h
2018-02-01
Full Text Available The popular replication formula to price variance swaps assumes continuity of traded option strikes. In practice, however, there is only a discrete set of option strikes traded on the market. We present here different discrete replication strategies and explain why the continuous replication price is more relevant.
Geometry and Hamiltonian mechanics on discrete spaces
Talasila, V.; Clemente Gallardo, J.J.; Clemente-Gallardo, J.; van der Schaft, Arjan
2004-01-01
Numerical simulation is often crucial for analysing the behaviour of many complex systems which do not admit analytic solutions. To this end, one either converts a 'smooth' model into a discrete (in space and time) model, or models systems directly at a discrete level. The goal of this paper is to
Wegner Estimate for Discrete Alloy-type Models
Veselić, Ivan
2010-10-01
We study discrete alloy-type random Schr\\"odinger operators on $\\ell^2(\\mathbb{Z}^d)$. Wegner estimates are bounds on the average number of eigenvalues in an energy interval of finite box restrictions of these types of operators. If the single site potential is compactly supported and the distribution of the coupling constant is of bounded variation a Wegner estimate holds. The bound is polynomial in the volume of the box and thus applicable as an ingredient for a localisation proof via multiscale analysis.
Multiple Discrete Endogenous Variables in Weakly-Separable Triangular Models
Directory of Open Access Journals (Sweden)
Sung Jae Jun
2016-02-01
Full Text Available We consider a model in which an outcome depends on two discrete treatment variables, where one treatment is given before the other. We formulate a three-equation triangular system with weak separability conditions. Without assuming assignment is random, we establish the identification of an average structural function using two-step matching. We also consider decomposing the effect of the first treatment into direct and indirect effects, which are shown to be identified by the proposed methodology. We allow for both of the treatment variables to be non-binary and do not appeal to an identification-at-infinity argument.
Handbook on modelling for discrete optimization
Pitsoulis, Leonidas; Williams, H
2006-01-01
The primary objective underlying the Handbook on Modelling for Discrete Optimization is to demonstrate and detail the pervasive nature of Discrete Optimization. While its applications cut across an incredibly wide range of activities, many of the applications are only known to specialists. It is the aim of this handbook to correct this. It has long been recognized that "modelling" is a critically important mathematical activity in designing algorithms for solving these discrete optimization problems. Nevertheless solving the resultant models is also often far from straightforward. In recent years it has become possible to solve many large-scale discrete optimization problems. However, some problems remain a challenge, even though advances in mathematical methods, hardware, and software technology have pushed the frontiers forward. This handbook couples the difficult, critical-thinking aspects of mathematical modeling with the hot area of discrete optimization. It will be done in an academic handbook treatment...
Indian Academy of Sciences (India)
2016-08-26
Aug 26, 2016 ... Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 9. Evolutionary Stable Strategy: Application of Nash Equilibrium in Biology. General ... Using some examples of classical games, we show how evolutionary game theory can help understand behavioural decisions of animals.
Kearney, M. Kate
2013-01-01
The concordance genus of a knot is the least genus of any knot in its concordance class. Although difficult to compute, it is a useful invariant that highlights the distinction between the three-genus and four-genus. In this paper we define and discuss the stable concordance genus of a knot, which describes the behavior of the concordance genus under connected sum.
Manifolds admitting stable forms
Czech Academy of Sciences Publication Activity Database
Le, Hong-Van; Panák, Martin; Vanžura, Jiří
2008-01-01
Roč. 49, č. 1 (2008), s. 101-11 ISSN 0010-2628 R&D Projects: GA ČR(CZ) GP201/05/P088 Institutional research plan: CEZ:AV0Z10190503 Keywords : stable forms * automorphism groups Subject RIV: BA - General Mathematics
International Nuclear Information System (INIS)
Ishida, T.
1992-01-01
The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs
Interactive Stable Ray Tracing
DEFF Research Database (Denmark)
Dal Corso, Alessandro; Salvi, Marco; Kolb, Craig
2017-01-01
Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-pr...
Directory of Open Access Journals (Sweden)
Behnaz Tolue
2018-07-01
Full Text Available In this paper we introduce stable subgroup graph associated to the group $G$. It is a graph with vertex set all subgroups of $G$ and two distinct subgroups $H_1$ and $H_2$ are adjacent if $St_{G}(H_1\\cap H_2\
Construction of energy-stable Galerkin reduced order models.
Energy Technology Data Exchange (ETDEWEB)
Kalashnikova, Irina; Barone, Matthew Franklin; Arunajatesan, Srinivasan; van Bloemen Waanders, Bart Gustaaf
2013-05-01
This report aims to unify several approaches for building stable projection-based reduced order models (ROMs). Attention is focused on linear time-invariant (LTI) systems. The model reduction procedure consists of two steps: the computation of a reduced basis, and the projection of the governing partial differential equations (PDEs) onto this reduced basis. Two kinds of reduced bases are considered: the proper orthogonal decomposition (POD) basis and the balanced truncation basis. The projection step of the model reduction can be done in two ways: via continuous projection or via discrete projection. First, an approach for building energy-stable Galerkin ROMs for linear hyperbolic or incompletely parabolic systems of PDEs using continuous projection is proposed. The idea is to apply to the set of PDEs a transformation induced by the Lyapunov function for the system, and to build the ROM in the transformed variables. The resulting ROM will be energy-stable for any choice of reduced basis. It is shown that, for many PDE systems, the desired transformation is induced by a special weighted L2 inner product, termed the %E2%80%9Csymmetry inner product%E2%80%9D. Attention is then turned to building energy-stable ROMs via discrete projection. A discrete counterpart of the continuous symmetry inner product, a weighted L2 inner product termed the %E2%80%9CLyapunov inner product%E2%80%9D, is derived. The weighting matrix that defines the Lyapunov inner product can be computed in a black-box fashion for a stable LTI system arising from the discretization of a system of PDEs in space. It is shown that a ROM constructed via discrete projection using the Lyapunov inner product will be energy-stable for any choice of reduced basis. Connections between the Lyapunov inner product and the inner product induced by the balanced truncation algorithm are made. Comparisons are also made between the symmetry inner product and the Lyapunov inner product. The performance of ROMs constructed
Random walks, random fields, and disordered systems
Černý, Jiří; Kotecký, Roman
2015-01-01
Focusing on the mathematics that lies at the intersection of probability theory, statistical physics, combinatorics and computer science, this volume collects together lecture notes on recent developments in the area. The common ground of these subjects is perhaps best described by the three terms in the title: Random Walks, Random Fields and Disordered Systems. The specific topics covered include a study of Branching Brownian Motion from the perspective of disordered (spin-glass) systems, a detailed analysis of weakly self-avoiding random walks in four spatial dimensions via methods of field theory and the renormalization group, a study of phase transitions in disordered discrete structures using a rigorous version of the cavity method, a survey of recent work on interacting polymers in the ballisticity regime and, finally, a treatise on two-dimensional loop-soup models and their connection to conformally invariant systems and the Gaussian Free Field. The notes are aimed at early graduate students with a mod...
Discrete frequency slice wavelet transform
Yan, Zhonghong; Tao, Ting; Jiang, Zhongwei; Wang, Haibin
2017-11-01
This paper introduces a new kind of Time-Frequency Representation (TFR) method called Discrete Frequency Slice Wavelet Transform (DFSWT). It is an improved version of Frequency Slice Wavelet Transform (FSWT). The previous researches on FSWT show that it is a new efficient TFR in an easy way without strict limitation as traditional wavelet theory. DFSWT as well as FSWT are defined directly in frequency domain, and still keep its properties in time-frequency domain as FSWT decomposition, reconstruction and filter design, etc. However, the original signal is decomposed and reconstructed on a Chosen Frequency Domains (CFD) as need of application. CFD means that the decomposition and reconstruction are not completed on all frequency components. At first, it is important to discuss the necessary condition of CFD to reconstruct the original signal. And then based on norm l2, an optimization algorithm is introduced to reconstruct the original signal even accurately. Finally, for a test example, the TFR analysis of a real life signal is shown. Some conclusions are drawn that the concept of CFD is very useful to application, and the DFSWT can become a simple and easy tool of TFR method, and also provide a new idea of low speed sampling of high frequency signal in applications.
Succinct Sampling from Discrete Distributions
DEFF Research Database (Denmark)
Bringmann, Karl; Larsen, Kasper Green
2013-01-01
We revisit the classic problem of sampling from a discrete distribution: Given n non-negative w-bit integers x_1,...,x_n, the task is to build a data structure that allows sampling i with probability proportional to x_i. The classic solution is Walker's alias method that takes, when implemented...... on a Word RAM, O(n) preprocessing time, O(1) expected query time for one sample, and n(w+2 lg n+o(1)) bits of space. Using the terminology of succinct data structures, this solution has redundancy 2n lg n+o(n) bits, i.e., it uses 2n lg n+o(n) bits in addition to the information theoretic minimum required...... requirement of the classic solution for a fundamental sampling problem, on the other hand, they provide the strongest known separation between the systematic and non-systematic case for any data structure problem. Finally, we also believe our upper bounds are practically efficient and simpler than Walker...
Asymptotic behavior of dynamical and control systems under perturbation and discretization
Grüne, Lars
2002-01-01
This book provides an approach to the study of perturbation and discretization effects on the long-time behavior of dynamical and control systems. It analyzes the impact of time and space discretizations on asymptotically stable attracting sets, attractors, asumptotically controllable sets and their respective domains of attractions and reachable sets. Combining robust stability concepts from nonlinear control theory, techniques from optimal control and differential games and methods from nonsmooth analysis, both qualitative and quantitative results are obtained and new algorithms are developed, analyzed and illustrated by examples.
Adaptive control of discrete-time chaotic systems: a fuzzy control approach
International Nuclear Information System (INIS)
Feng Gang; Chen Guanrong
2005-01-01
This paper discusses adaptive control of a class of discrete-time chaotic systems from a fuzzy control approach. Using the T-S model of discrete-time chaotic systems, an adaptive control algorithm is developed based on some conventional adaptive control techniques. The resulting adaptively controlled chaotic system is shown to be globally stable, and its robustness is discussed. A simulation example of the chaotic Henon map control is finally presented, to illustrate an application and the performance of the proposed control algorithm
2018-01-12
tV e −u/γ ] = ( 1 + te−u/γ )−1 and ∫ J(u, t)du = γ log ( eu/γ + t ) . Using the antiderivative to evaluate the integrals in the formula for BK... Journal of Statistics, 26(2):283–297, 1998. J. F. C. Kingman. Completely random measures. Pacific Journal of Mathematics, 21(1):59–78, 1967. T S Ferguson...Random discrete distributions. Journal of the Royal Statistical Society B, 37(1): 1–22, 1975. Anders Brix. Generalized gamma measures and shot-noise cox
Compatible Spatial Discretizations for Partial Differential Equations
Energy Technology Data Exchange (ETDEWEB)
Arnold, Douglas, N, ed.
2004-11-25
From May 11--15, 2004, the Institute for Mathematics and its Applications held a hot topics workshop on Compatible Spatial Discretizations for Partial Differential Equations. The numerical solution of partial differential equations (PDE) is a fundamental task in science and engineering. The goal of the workshop was to bring together a spectrum of scientists at the forefront of the research in the numerical solution of PDEs to discuss compatible spatial discretizations. We define compatible spatial discretizations as those that inherit or mimic fundamental properties of the PDE such as topology, conservation, symmetries, and positivity structures and maximum principles. A wide variety of discretization methods applied across a wide range of scientific and engineering applications have been designed to or found to inherit or mimic intrinsic spatial structure and reproduce fundamental properties of the solution of the continuous PDE model at the finite dimensional level. A profusion of such methods and concepts relevant to understanding them have been developed and explored: mixed finite element methods, mimetic finite differences, support operator methods, control volume methods, discrete differential forms, Whitney forms, conservative differencing, discrete Hodge operators, discrete Helmholtz decomposition, finite integration techniques, staggered grid and dual grid methods, etc. This workshop seeks to foster communication among the diverse groups of researchers designing, applying, and studying such methods as well as researchers involved in practical solution of large scale problems that may benefit from advancements in such discretizations; to help elucidate the relations between the different methods and concepts; and to generally advance our understanding in the area of compatible spatial discretization methods for PDE. Particular points of emphasis included: + Identification of intrinsic properties of PDE models that are critical for the fidelity of numerical
On the definition of discrete hydrodynamic variables
Español, Pep; Zúñiga, Ignacio
2009-10-01
The Green-Kubo formula for discrete hydrodynamic variables involves information about not only the fluid transport coefficients but also about discrete versions of the differential operators that govern the evolution of the discrete variables. This gives an intimate connection between discretization procedures in fluid dynamics and coarse-graining procedures used to obtain hydrodynamic behavior of molecular fluids. We observed that a natural definition of discrete hydrodynamic variables in terms of Voronoi cells leads to a Green-Kubo formula which is divergent, rendering the full coarse-graining strategy useless. In order to understand this subtle issue, in the present paper we consider the coarse graining of noninteracting Brownian particles. The discrete hydrodynamic variable for this problem is the number of particles within Voronoi cells. Thanks to the simplicity of the model we spot the origin of the singular behavior of the correlation functions. We offer an alternative definition, based on the concept of a Delaunay cell that behaves properly, suggesting the use of the Delaunay construction for the coarse graining of molecular fluids at the discrete hydrodynamic level.
A belief-based evolutionarily stable strategy
Deng, Xinyang; Wang, Zhen; Liu, Qi; Deng, Yong; Mahadevan, Sankaran
2014-01-01
As an equilibrium refinement of the Nash equilibrium, evolutionarily stable strategy (ESS) is a key concept in evolutionary game theory and has attracted growing interest. An ESS can be either a pure strategy or a mixed strategy. Even though the randomness is allowed in mixed strategy, the selection probability of pure strategy in a mixed strategy may fluctuate due to the impact of many factors. The fluctuation can lead to more uncertainty. In this paper, such uncertainty involved in mixed st...
Higher dimensional discrete Cheeger inequalities
Directory of Open Access Journals (Sweden)
Anna Gundert
2015-01-01
Full Text Available For graphs there exists a strong connection between spectral and combinatorial expansion properties. This is expressed, e.g., by the discrete Cheeger inequality, the lower bound of which states that $\\lambda(G \\leq h(G$, where $\\lambda(G$ is the second smallest eigenvalue of the Laplacian of a graph $G$ and $h(G$ is the Cheeger constant measuring the edge expansion of $G$. We are interested in generalizations of expansion properties to finite simplicial complexes of higher dimension (or uniform hypergraphs. Whereas higher dimensional Laplacians were introduced already in 1945 by Eckmann, the generalization of edge expansion to simplicial complexes is not straightforward. Recently, a topologically motivated notion analogous to edge expansion that is based on $\\mathbb{Z}_2$-cohomology was introduced by Gromov and independently by Linial, Meshulam and Wallach. It is known that for this generalization there is no direct higher dimensional analogue of the lower bound of the Cheeger inequality. A different, combinatorially motivated generalization of the Cheeger constant, denoted by $h(X$, was studied by Parzanchevski, Rosenthal and Tessler. They showed that indeed $\\lambda(X \\leq h(X$, where $\\lambda(X$ is the smallest non-trivial eigenvalue of the ($(k-1$-dimensional upper Laplacian, for the case of $k$-dimensional simplicial complexes $X$ with complete $(k-1$-skeleton. Whether this inequality also holds for $k$-dimensional complexes with non-com\\-plete$(k-1$-skeleton has been an open question.We give two proofs of the inequality for arbitrary complexes. The proofs differ strongly in the methods and structures employed,and each allows for a different kind of additional strengthening of the original result.
International Nuclear Information System (INIS)
Tibari, Elghali; Taous, Fouad; Marah, Hamid
2014-01-01
This report presents results related to stable isotopes analysis carried out at the CNESTEN DASTE in Rabat (Morocco), on behalf of Senegal. These analyzes cover 127 samples. These results demonstrate that Oxygen-18 and Deuterium in water analysis were performed by infrared Laser spectroscopy using a LGR / DLT-100 with Autosampler. Also, the results are expressed in δ values (‰) relative to V-SMOW to ± 0.3 ‰ for oxygen-18 and ± 1 ‰ for deuterium.
Forensic Stable Isotope Biogeochemistry
Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.
2016-06-01
Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.
Comparing Fréchet and positive stable laws
Simon, Thomas
2014-01-01
To appear in Electronic Journal of Probability; Let ${\\bf L}$ be the unit exponential random variable and ${\\bf Z}_\\alpha$ the standard positive $\\alpha$-stable random variable. We prove that $\\{(1-\\alpha) \\alpha^{\\gamma_\\alpha} {\\bf Z}_\\alpha^{-\\gamma_\\alpha}, 0< \\alpha
Thermodynamics of discrete-charge quantum circuits
Energy Technology Data Exchange (ETDEWEB)
Utreras-Díaz, C.A., E-mail: cutreras@uach.cl [Instituto de Ciencias Físicas y Matemáticas, Facultad de Ciencias, Universidad Austral de Chile, Campus Isla Teja s/n, Casilla 567, Valdivia (Chile); Laroze, D., E-mail: dlarozen@uta.cl [Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica (Chile); SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)
2015-11-01
We study a dilute gas made of quantum circuits with discrete charge, interacting with a thermal reservoir at absolute temperature T, using Boltzmann statistics. This system is described by a quantum Hamiltonian that explicitly includes the effect of the discrete nature of the electric charge within a circuit approach. The eigenfunctions can be expressed as solutions of the Mathieu equation, and the energy spectrum is related to its characteristic values. We also make a comparative numerical study of the thermal properties, between the quantum case with discrete charge, and the so-called semiclassical approximation.
Discrete Flavour Symmetries from the Heisenberg Group
Floratos, E.G.
2016-01-01
Non-abelian discrete symmetries are of particular importance in model building. They are mainly invoked to explain the various fermion mass hierarchies and forbid dangerous superpotential terms. In string models they are usually associated to the geometry of the compactification manifold and more particularly to the magnetised branes in toroidal compactifications. Motivated by these facts, in this note we propose a unified framework to construct representations of finite discrete family groups based on the automorphisms of the discrete and finite Heisenberg group. We focus in particular in the $PSL_2(p)$ groups which contain the phenomenologically interesting cases.
Discrete-Time Biomedical Signal Encryption
Directory of Open Access Journals (Sweden)
Victor Grigoraş
2017-12-01
Full Text Available Chaotic modulation is a strong method of improving communication security. Analog and discrete chaotic systems are presented in actual literature. Due to the expansion of digital communication, discrete-time systems become more efficient and closer to actual technology. The present contribution offers an in-depth analysis of the effects chaos encryption produce on 1D and 2D biomedical signals. The performed simulations show that modulating signals are precisely recovered by the synchronizing receiver if discrete systems are digitally implemented and the coefficients precisely correspond. Channel noise is also applied and its effects on biomedical signal demodulation are highlighted.
Ensemble simulations with discrete classical dynamics
DEFF Research Database (Denmark)
Toxværd, Søren
2013-01-01
{E}(h)$ is employed to determine the relation with the corresponding energy, $E$ for the analytic dynamics with $h=0$ and the zero-order estimate $E_0(h)$ of the energy for discrete dynamics, appearing in the literature for MD with VA. We derive a corresponding time reversible VA algorithm for canonical dynamics......For discrete classical Molecular dynamics (MD) obtained by the "Verlet" algorithm (VA) with the time increment $h$ there exist a shadow Hamiltonian $\\tilde{H}$ with energy $\\tilde{E}(h)$, for which the discrete particle positions lie on the analytic trajectories for $\\tilde{H}$. $\\tilde...
Discrete Tomography and Imaging of Polycrystalline Structures
DEFF Research Database (Denmark)
Alpers, Andreas
Laboratory for Sustainable Energy), for instance, we study polycrystalline materials via synchrotron X-ray diffraction. Several reconstruction problems arise, most of them exhibit inherently discrete aspects. In this talk I want to give a concise mathematical introduction to some of these reconstruction...... problems. Special focus is on their relationship to classical discrete tomography. Several open mathematical questions will be mentioned along the way.......High resolution transmission electron microscopy is commonly considered as the standard application for discrete tomography. While this has yet to be technically realized, new applications with a similar flavor have emerged in materials science. In our group at Ris� DTU (Denmark's National...
Hairs of discrete symmetries and gravity
Directory of Open Access Journals (Sweden)
Kang Sin Choi
2017-06-01
Full Text Available Gauge symmetries are known to be respected by gravity because gauge charges carry flux lines, but global charges do not carry flux lines and are not conserved by gravitational interaction. For discrete symmetries, they are spontaneously broken in the Universe, forming domain walls. Since the realization of discrete symmetries in the Universe must involve the vacuum expectation values of Higgs fields, a string-like configuration (hair at the intersection of domain walls in the Higgs vacua can be realized. Therefore, we argue that discrete charges are also respected by gravity.
Hairs of discrete symmetries and gravity
Energy Technology Data Exchange (ETDEWEB)
Choi, Kang Sin [Scranton Honors Program, Ewha Womans University, Seodaemun-Gu, Seoul 03760 (Korea, Republic of); Center for Fields, Gravity and Strings, CTPU, Institute for Basic Sciences, Yuseong-Gu, Daejeon 34047 (Korea, Republic of); Kim, Jihn E., E-mail: jihnekim@gmail.com [Department of Physics, Kyung Hee University, 26 Gyungheedaero, Dongdaemun-Gu, Seoul 02447 (Korea, Republic of); Center for Axion and Precision Physics Research (IBS), 291 Daehakro, Yuseong-Gu, Daejeon 34141 (Korea, Republic of); Kyae, Bumseok [Department of Physics, Pusan National University, 2 Busandaehakro-63-Gil, Geumjeong-Gu, Busan 46241 (Korea, Republic of); Nam, Soonkeon [Department of Physics, Kyung Hee University, 26 Gyungheedaero, Dongdaemun-Gu, Seoul 02447 (Korea, Republic of)
2017-06-10
Gauge symmetries are known to be respected by gravity because gauge charges carry flux lines, but global charges do not carry flux lines and are not conserved by gravitational interaction. For discrete symmetries, they are spontaneously broken in the Universe, forming domain walls. Since the realization of discrete symmetries in the Universe must involve the vacuum expectation values of Higgs fields, a string-like configuration (hair) at the intersection of domain walls in the Higgs vacua can be realized. Therefore, we argue that discrete charges are also respected by gravity.
Discrete element modeling approach to porosimetry for durability risk estimation of concrete
Stroeven, P.; Le, N.L.B.; Stroeven, M.; Sluys, L.J.
2011-01-01
The paper introduces a novel approach to porosimetry in virtual concrete, denoted as random node structuring (RNS). The fresh state of this particulate material is produced by the DEM system HADES. Hydration simulation is a hybrid approach making use of wellknown discretization and vector methods.
Persistence of a continuous stochastic process with discrete-time sampling: non-Markov processes.
Ehrhardt, George C M A; Bray, Alan J; Majumdar, Satya N
2002-04-01
We consider the problem of "discrete-time persistence," which deals with the zero crossings of a continuous stochastic process X(T) measured at discrete times T=nDeltaT. For a Gaussian stationary process the persistence (no crossing) probability decays as exp(-theta(D)T)=[rho(a)](n) for large n, where a=exp(-DeltaT/2) and the discrete persistence exponent theta(D) is given by theta(D)=(ln rho)/(2 ln a). Using the "independent interval approximation," we show how theta(D) varies with DeltaT for small DeltaT and conclude that experimental measurements of persistence for smooth processes, such as diffusion, are less sensitive to the effects of discrete sampling than measurements of a randomly accelerated particle or random walker. We extend the matrix method developed by us previously [Phys. Rev. E 64, 015101(R) (2001)] to determine rho(a) for a two-dimensional random walk and the one-dimensional random-acceleration problem. We also consider "alternating persistence," which corresponds to a<0, and calculate rho(a) for this case.
A practical test for the choice of mixing distribution in discrete choice models
DEFF Research Database (Denmark)
Fosgerau, Mogens; Bierlaire, Michel
2007-01-01
The choice of a specific distribution for random parameters of discrete choice models is a critical issue in transportation analysis. Indeed, various pieces of research have demonstrated that an inappropriate choice of the distribution may lead to serious bias in model forecast and in the estimated...
Two-player nonZero-sum stopping games in discrete time
Shmaya, Eran; Solan, Eilon
2004-01-01
We prove that every two-player nonzero-sum stopping game in discrete time admits an \\epsilon-equilibrium in randomized strategies for every \\epsilon >0. We use a stochastic variation of Ramsey's theorem, which enables us to reduce the problem to that of studying properties of \\epsilon-equilibria in a simple class of stochastic games with finite state space.
Wang, Shenquan; Feng, Jian; Jiang, Yulian
2016-05-01
The fault detection (FD) problem for discrete-time fuzzy networked systems with time-varying delay and multiple packet losses is investigated in this paper. The communication links between the plant and the FD filter (FDF) are assumed to be imperfect, and the missing probability is governed by an individual random variable satisfying a certain probabilistic distribution over the interval [0 1]. The discrete-time delayed fuzzy networked system is first transformed into the form of interconnect ion of two subsystems by applying an input-output method and a two-term approximation approach, which are employed to approximate the time-varying delay. Our attention is focused on the design of fuzzy FDF (FFDF) such that, for all data missing conditions, the overall FD dynamics are input-output stable in mean square and preserves a guaranteed performance. Sufficient conditions are first established via H∞ performance analysis for the existence of the desired FFDF; meanwhile, the corresponding solvability conditions for the desired FFDF gains are characterised in terms of the feasibility of a convex optimisation problem. Moreover, we show that the obtained criteria based on the input-output approach can also be established by applying the direct Lyapunov method to the original time-delay systems. Finally, simulation examples are provided to demonstrate the effectiveness of the proposed approaches.
Migliorati, Giovanni
2016-01-05
We review the main results achieved in the analysis of the stability and accuracy of the discrete leastsquares approximation on multivariate polynomial spaces, with noiseless evaluations at random points, noiseless evaluations at low-discrepancy point sets, and noisy evaluations at random points.
Di Pietro, Daniele A.; Marche, Fabien
2018-02-01
In this paper, we further investigate the use of a fully discontinuous Finite Element discrete formulation for the study of shallow water free surface flows in the fully nonlinear and weakly dispersive flow regime. We consider a decoupling strategy in which we approximate the solutions of the classical shallow water equations supplemented with a source term globally accounting for the non-hydrostatic effects. This source term can be computed through the resolution of elliptic second-order linear sub-problems, which only involve second order partial derivatives in space. We then introduce an associated Symmetric Weighted Internal Penalty discrete bilinear form, allowing to deal with the discontinuous nature of the elliptic problem's coefficients in a stable and consistent way. Similar discrete formulations are also introduced for several recent optimized fully nonlinear and weakly dispersive models. These formulations are validated again several benchmarks involving h-convergence, p-convergence and comparisons with experimental data, showing optimal convergence properties.
Directory of Open Access Journals (Sweden)
Chellaboina Vijaysekhar
2005-01-01
Full Text Available We develop thermodynamic models for discrete-time large-scale dynamical systems. Specifically, using compartmental dynamical system theory, we develop energy flow models possessing energy conservation, energy equipartition, temperature equipartition, and entropy nonconservation principles for discrete-time, large-scale dynamical systems. Furthermore, we introduce a new and dual notion to entropy; namely, ectropy, as a measure of the tendency of a dynamical system to do useful work and grow more organized, and show that conservation of energy in an isolated thermodynamic system necessarily leads to nonconservation of ectropy and entropy. In addition, using the system ectropy as a Lyapunov function candidate, we show that our discrete-time, large-scale thermodynamic energy flow model has convergent trajectories to Lyapunov stable equilibria determined by the system initial subsystem energies.
Comparing the Discrete and Continuous Logistic Models
Gordon, Sheldon P.
2008-01-01
The solutions of the discrete logistic growth model based on a difference equation and the continuous logistic growth model based on a differential equation are compared and contrasted. The investigation is conducted using a dynamic interactive spreadsheet. (Contains 5 figures.)
Can time be a discrete dynamical variable
International Nuclear Information System (INIS)
Lee, T.D.
1983-01-01
The possibility that time can be regarded as a discrete dynamical variable is examined through all phases of mechanics: from classical mechanics to nonrelativistic quantum mechanics, and to relativistic quantum field theories. (orig.)
Breatherlike impurity modes in discrete nonlinear lattices
DEFF Research Database (Denmark)
Hennig, D.; Rasmussen, Kim; Tsironis, G. P.
1995-01-01
We investigate the properties of a disordered generalized discrete nonlinear Schrodinger equation, containing both diagonal and nondiagonal nonlinear terms. The equation models a Linear host lattice doped with nonlinear impurities. We find different types of impurity states that form itinerant...
Confining and Structuring Discretion: Discretionary Justice
Davis, Kenneth Culp
1971-01-01
Locate the injustice in our entire government and legal system in order to best improve the quality of justice to individuals where decisions are made by discretion and not by rule or principles. (Editor/IR)
Running Parallel Discrete Event Simulators on Sierra
Energy Technology Data Exchange (ETDEWEB)
Barnes, P. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jefferson, D. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-12-03
In this proposal we consider porting the ROSS/Charm++ simulator and the discrete event models that run under its control so that they run on the Sierra architecture and make efficient use of the Volta GPUs.
Quotient of manifolds by discrete groups
International Nuclear Information System (INIS)
Ardalan, F.; Arfaei, H.
1985-09-01
Quotient of manifolds by discrete subgroups of their isometry group are considered. In particular, symmetry breaking due to the quotient structure, topological properties and harmonic analysis of the resultant manifolds are discussed and illustrated by two dimensional examples. (author)
Memorized discrete systems and time-delay
Luo, Albert C J
2017-01-01
This book examines discrete dynamical systems with memory—nonlinear systems that exist extensively in biological organisms and financial and economic organizations, and time-delay systems that can be discretized into the memorized, discrete dynamical systems. It book further discusses stability and bifurcations of time-delay dynamical systems that can be investigated through memorized dynamical systems as well as bifurcations of memorized nonlinear dynamical systems, discretization methods of time-delay systems, and periodic motions to chaos in nonlinear time-delay systems. The book helps readers find analytical solutions of MDS, change traditional perturbation analysis in time-delay systems, detect motion complexity and singularity in MDS; and determine stability, bifurcation, and chaos in any time-delay system.
On organizing principles of discrete differential geometry. Geometry of spheres
International Nuclear Information System (INIS)
Bobenko, Alexander I; Suris, Yury B
2007-01-01
Discrete differential geometry aims to develop discrete equivalents of the geometric notions and methods of classical differential geometry. This survey contains a discussion of the following two fundamental discretization principles: the transformation group principle (smooth geometric objects and their discretizations are invariant with respect to the same transformation group) and the consistency principle (discretizations of smooth parametrized geometries can be extended to multidimensional consistent nets). The main concrete geometric problem treated here is discretization of curvature-line parametrized surfaces in Lie geometry. Systematic use of the discretization principles leads to a discretization of curvature-line parametrization which unifies circular and conical nets.
Definable maximal discrete sets in forcing extensions
DEFF Research Database (Denmark)
Törnquist, Asger Dag; Schrittesser, David
2018-01-01
Let be a Σ11 binary relation, and recall that a set A is -discrete if no two elements of A are related by . We show that in the Sacks and Miller forcing extensions of L there is a Δ12 maximal -discrete set. We use this to answer in the negative the main question posed in [5] by showing...
Nonlinear integrodifferential equations as discrete systems
Tamizhmani, K. M.; Satsuma, J.; Grammaticos, B.; Ramani, A.
1999-06-01
We analyse a class of integrodifferential equations of the `intermediate long wave' (ILW) type. We show that these equations can be formally interpreted as discrete, differential-difference systems. This allows us to link equations of this type with previous results of ours involving differential-delay equations and, on the basis of this, propose new integrable equations of ILW type. Finally, we extend this approach to pure difference equations and propose ILW forms for the discrete lattice KdV equation.
't Hooft anomaly matching for discrete symmetries
International Nuclear Information System (INIS)
Csaki, C.; Murayama, Hitoshi; Lawrence Berkeley National Lab., CA
1998-05-01
The authors show how to extend the 't Hooft anomaly matching conditions to discrete symmetries. They check these discrete anomally matching conditions on several proposed low-energy spectra of certain strongly interacting gauge theories. The excluded examples include the proposed chirally symmetric vacuum of pure N = 1 supersymmetric yang-Mills theories, certain non-supersymmetric confining theories and some self-dual N = 1 supersymmetric theories based on exceptional groups
Quadratic Term Structure Models in Discrete Time
Marco Realdon
2006-01-01
This paper extends the results on quadratic term structure models in continuos time to the discrete time setting. The continuos time setting can be seen as a special case of the discrete time one. Recursive closed form solutions for zero coupon bonds are provided even in the presence of multiple correlated underlying factors. Pricing bond options requires simple integration. Model parameters may well be time dependent without scuppering such tractability. Model estimation does not require a r...
Discrete symmetries and solar neutrino mixing
Energy Technology Data Exchange (ETDEWEB)
Kapetanakis, D.; Mayr, P.; Nilles, H.P. (Physik Dept., Technische Univ. Muenchen, Garching (Germany) Max-Planck-Inst. fuer Physik, Werner-Heisenberg-Inst., Muenchen (Germany))
1992-05-21
We study the question of resonant solar neutrino mixing in the framework of the supersymmetric extension of the standard model. Discrete symmetries that are consistent with solar neutrino mixing and proton stability are classified. In the minimal model they are shown to lead to two distinct patterns of allowed dimension-four operators. Imposing anomaly freedom, only three different discrete Z{sub N}-symmetries (with N=2, 3, 6) are found to be phenomenologically acceptable. (orig.).
Discrete symmetries and solar neutrino mixing
International Nuclear Information System (INIS)
Kapetanakis, D.; Mayr, P.; Nilles, H.P.
1992-01-01
We study the question of resonant solar neutrino mixing in the framework of the supersymmetric extension of the standard model. Discrete symmetries that are consistent with solar neutrino mixing and proton stability are classified. In the minimal model they are shown to lead to two distinct patterns of allowed dimension-four operators. Imposing anomaly freedom, only three different discrete Z N -symmetries (with N=2, 3, 6) are found to be phenomenologically acceptable. (orig.)
Discrete symmetries and coset space dimensional reduction
International Nuclear Information System (INIS)
Kapetanakis, D.; Zoupanos, G.
1989-01-01
We consider the discrete symmetries of all the six-dimensional coset spaces and we apply them in gauge theories defined in ten dimensions which are dimensionally reduced over these homogeneous spaces. Particular emphasis is given in the consequences of the discrete symmetries on the particle content as well as on the symmetry breaking a la Hosotani of the resulting four-dimensional theory. (orig.)
On discrete models of space-time
International Nuclear Information System (INIS)
Horzela, A.; Kempczynski, J.; Kapuscik, E.; Georgia Univ., Athens, GA; Uzes, Ch.
1992-02-01
Analyzing the Einstein radiolocation method we come to the conclusion that results of any measurement of space-time coordinates should be expressed in terms of rational numbers. We show that this property is Lorentz invariant and may be used in the construction of discrete models of space-time different from the models of the lattice type constructed in the process of discretization of continuous models. (author)
Application of multivariate splines to discrete mathematics
Xu, Zhiqiang
2005-01-01
Using methods developed in multivariate splines, we present an explicit formula for discrete truncated powers, which are defined as the number of non-negative integer solutions of linear Diophantine equations. We further use the formula to study some classical problems in discrete mathematics as follows. First, we extend the partition function of integers in number theory. Second, we exploit the relation between the relative volume of convex polytopes and multivariate truncated powers and giv...
Infinite Random Graphs as Statistical Mechanical Models
DEFF Research Database (Denmark)
Durhuus, Bergfinnur Jøgvan; Napolitano, George Maria
2011-01-01
We discuss two examples of infinite random graphs obtained as limits of finite statistical mechanical systems: a model of two-dimensional dis-cretized quantum gravity defined in terms of causal triangulated surfaces, and the Ising model on generic random trees. For the former model we describe...
Mohamed, Mamdouh S.
2016-02-11
A conservative discretization of incompressible Navier–Stokes equations is developed based on discrete exterior calculus (DEC). A distinguishing feature of our method is the use of an algebraic discretization of the interior product operator and a combinatorial discretization of the wedge product. The governing equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. The discretization is then carried out by substituting with the corresponding discrete operators based on the DEC framework. Numerical experiments for flows over surfaces reveal a second order accuracy for the developed scheme when using structured-triangular meshes, and first order accuracy for otherwise unstructured meshes. By construction, the method is conservative in that both mass and vorticity are conserved up to machine precision. The relative error in kinetic energy for inviscid flow test cases converges in a second order fashion with both the mesh size and the time step.
Theoretical Basics of Teaching Discrete Mathematics
Directory of Open Access Journals (Sweden)
Y. A. Perminov
2012-01-01
Full Text Available The paper deals with the research findings concerning the process of mastering the theoretical basics of discrete mathematics by the students of vocational pedagogic profile. The methodological analysis is based on the subject and functions of the modern discrete mathematics and its role in mathematical modeling and computing. The modern discrete mathematics (i.e. mathematics of the finite type structures plays the important role in modernization of vocational training. It is especially rele- vant to training students for vocational pedagogic qualifications, as in the future they will be responsible for training the middle and the senior level specialists in engineer- ing and technical spheres. Nowadays in different industries, there arise the problems which require for their solving both continual – based on the classical mathematical methods – and discrete modeling. The teaching course of discrete mathematics for the future vocational teachers should be relevant to the target qualification and aimed at mastering the mathematical modeling, systems of computer mathematics and computer technologies. The author emphasizes the fundamental role of mastering the language of algebraic and serial structures, as well as the logical, algorithmic, combinatory schemes dominating in dis- crete mathematics. The guidelines for selecting the content of the course in discrete mathematics are specified. The theoretical findings of the research can be put into practice whilst developing curricula and working programs for bachelors and masters’ training.
Recent developments in discrete ordinates electron transport
International Nuclear Information System (INIS)
Morel, J.E.; Lorence, L.J. Jr.
1986-01-01
The discrete ordinates method is a deterministic method for numerically solving the Boltzmann equation. It was originally developed for neutron transport calculations, but is routinely used for photon and coupled neutron-photon transport calculations as well. The computational state of the art for coupled electron-photon transport (CEPT) calculations is not as developed as that for neutron transport calculations. The only production codes currently available for CEPT calculations are condensed-history Monte Carlo codes such as the ETRAN and ITS codes. A deterministic capability for production calculations is clearly needed. In response to this need, we have begun the development of a production discrete ordinates code for CEPT calculations. The purpose of this paper is to describe the basic approach we are taking, discuss the current status of the project, and present some new computational results. Although further characterization of the coupled electron-photon discrete ordinates method remains to be done, the results to date indicate that the discrete ordinates method can be just as accurate and from 10 to 100 times faster than the Monte Carlo method for a wide variety of problems. We stress that these results are obtained with standard discrete ordinates codes such as ONETRAN. It is clear that even greater efficiency can be obtained by developing a new generation of production discrete ordinates codes specifically designed to solve the Boltzmann-Fokker-Planck equation. However, the prospects for such development in the near future appear to be remote
Discrete modeling considerations in multiphase fluid dynamics
International Nuclear Information System (INIS)
Ransom, V.H.; Ramshaw, J.D.
1988-01-01
The modeling of multiphase flows play a fundamental role in light water reactor safety. The main ingredients in our discrete modeling Weltanschauung are the following considerations: (1) Any physical model must be cast into discrete form for a digital computer. (2) The usual approach of formulating models in differential form and then discretizing them is potentially hazardous. It may be preferable to formulate the model in discrete terms from the outset. (3) Computer time and storage constraints limit the resolution that can be employed in practical calculations. These limits effectively define the physical phenomena, length scales, and time scales which cannot be directly represented in the calculation and therefore must be modeled. This information should be injected into the model formulation process at an early stage. (4) Practical resolution limits are generally so coarse that traditional convergence and truncation-error analyses become irrelevant. (5) A discrete model constitutes a reduced description of a physical system, from which fine-scale details are eliminated. This elimination creates a statistical closure problem. Methods from statistical physics may therefore be useful in the formulation of discrete models. In the present paper we elaborate on these themes and illustrate them with simple examples. 48 refs
Discrete symmetries and their stringy origin
International Nuclear Information System (INIS)
Mayorga Pena, Damian Kaloni
2014-05-01
Discrete symmetries have proven to be very useful in controlling the phenomenology of theories beyond the standard model. In this work we explore how these symmetries emerge from string compactifications. Our approach is twofold: On the one hand, we consider the heterotic string on orbifold backgrounds. In this case the discrete symmetries can be derived from the orbifold conformal field theory, and it can be shown that they are in close relation with the orbifold geometry. We devote special attention to R-symmetries, which arise from discrete remnants of the Lorentz group in compact space. Further we discuss the physical implications of these symmetries both in the heterotic mini-landscape and in newly constructed models based on the Z 2 x Z 4 orbifold. In both cases we observe that the discrete symmetries favor particular locations in the orbifold where the particles of standard model should live. On the other hand we consider a class of F-theory models exhibiting an SU(5) gauge group, times additional U(1) symmetries. In this case, the smooth compactification background does not permit us to track the discrete symmetries as transparently as in orbifold models. Hence, we follow a different approach and search for discrete subgroups emerging after the U(1)s are broken. We observe that in this approach it is possible to obtain the standard Z 2 matter parity of the MSSM.
On stochastic differential equations with random delay
International Nuclear Information System (INIS)
Krapivsky, P L; Luck, J M; Mallick, K
2011-01-01
We consider stochastic dynamical systems defined by differential equations with a uniform random time delay. The latter equations are shown to be equivalent to deterministic higher-order differential equations: for an nth-order equation with random delay, the corresponding deterministic equation has order n + 1. We analyze various examples of dynamical systems of this kind, and find a number of unusual behaviors. For instance, for the harmonic oscillator with random delay, the energy grows as exp((3/2) t 2/3 ) in reduced units. We then investigate the effect of introducing a discrete time step ε. At variance with the continuous situation, the discrete random recursion relations thus obtained have intrinsic fluctuations. The crossover between the fluctuating discrete problem and the deterministic continuous one as ε goes to zero is studied in detail on the example of a first-order linear differential equation
Efficient water table evolution discretization using domain transformation
DEFF Research Database (Denmark)
Boon, W. M.; Balbarini, Nicola; Binning, Philip John
2017-01-01
Domain transformation methods are useful techniques for solving problems on non-stationary domains. In this work, we consider the evolution of the water table in an unconfined aquifer. This nonlinear, time-dependent problem is greatly simplified by using a mapping from the physical domain to a re...... to a reference domain and is then further reduced to a single, (nonlinear) partial differential equation. We show well-posedness of the approach and propose a stable and convergent discretization scheme. Numerical results are presented supporting the theory.......Domain transformation methods are useful techniques for solving problems on non-stationary domains. In this work, we consider the evolution of the water table in an unconfined aquifer. This nonlinear, time-dependent problem is greatly simplified by using a mapping from the physical domain...
Orthogonal functions, discrete variable representation, and generalized gauss quadratures
DEFF Research Database (Denmark)
Schneider, B. I.; Nygaard, Nicolai
2002-01-01
in the original representation. This has been exploited in bound-state, scattering, and time-dependent problems using the so-called, discrete variable representation (DVR). At the core of this approach is the mathematical three-term recursion relationship satisfied by the classical orthogonal functions......, the distinction between spectral and grid approaches becomes blurred. In fact, the two approaches can be related by a similarity transformation. By the exploitation of this idea, calculations can be considerably simplified by removing the need to compute difficult matrix elements of the Hamiltonian...... functions, this is not the case. However, they may be computed in a stable numerical fashion, via the recursion. In essence, this is an application of the well-known Lanczos recursion approach. Once the recursion coefficients are known, it is possible to compute the points and weights of quadratures on...
Discretizations in isogeometric analysis of Navier-Stokes flow
DEFF Research Database (Denmark)
Nielsen, Peter Nørtoft; Gersborg, Allan Roulund; Gravesen, Jens
2011-01-01
This paper deals with isogeometric analysis of 2-dimensional, steady state, incompressible Navier-Stokes flow subjected to Dirichlet boundary conditions. We present a detailed description of the numerical method used to solve the boundary value problem. Numerical inf-sup stability tests for the s......This paper deals with isogeometric analysis of 2-dimensional, steady state, incompressible Navier-Stokes flow subjected to Dirichlet boundary conditions. We present a detailed description of the numerical method used to solve the boundary value problem. Numerical inf-sup stability tests...... for the simplified Stokes problem confirm the existence of many stable discretizations of the velocity and pressure spaces, and in particular show that stability may be achieved by means of knot refinement of the velocity space. Error convergence studies for the full Navier-Stokes problem show optimal convergence...
Development of a Discrete Mass Inflow Boundary Condition for MFIX
Directory of Open Access Journals (Sweden)
Jordan Musser
2011-02-01
Full Text Available MFIX (Multiphase Flow with Interphase eXchanges is an open source software package developed by the National Energy Technology Laboratory (NETL used for modeling the chemical reactions, heat transfer, and hydrodynamics of fluid-solid systems. Currently, the stable publically available release of MFIX does not include a discrete mass inflow boundary condition (DMIBC for its discrete element method (DEM package. Inflow boundary conditions are useful for simulating systems where particles are consumed through chemical reactions and an incoming feed is necessary to sustain the reaction. To implement the DMIBC an inlet staging area is designated outside the computational domain and particles are passed through the wall region associated with the inlet. Forces incurred on entering particles, generated from collisions with particles already in the system, are ignored whereas, particles already in the system respond to contact forces and react accordingly, moving away from the inlet. This approach prevents any unphysical overlap between new and existing particles. It also ensures that particles entering the system will enter the computational domain regardless of opposing forces. Once an incoming particle is fully within the domain, it reacts appropriately to any and all contact force. This approach for a DMIBC has been implemented and is available within the current development version of MFIX.
Discrete Particle Method for Simulating Hypervelocity Impact Phenomena
Directory of Open Access Journals (Sweden)
Erkai Watson
2017-04-01
Full Text Available In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI phenomena which is based on the Discrete Element Method (DEM. Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 kms-1. We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact. We model a typical HVI experiment configuration where a sphere strikes a thin plate and investigate the properties of the resulting debris cloud. We provide a quantitative computational analysis of the resulting debris cloud caused by impact and a comprehensive parameter study by varying key parameters of our model. We compare our findings from the simulations with recent HVI experiments performed at our institute. Our findings are that the DEM method leads to very stable, energy–conserving simulations of HVI scenarios that map the experimental setup where a sphere strikes a thin plate at hypervelocity speed. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength.
Lyapunov Schmidt reduction algorithm for three-dimensional discrete vortices
Lukas, Mike; Pelinovsky, Dmitry; Kevrekidis, P. G.
2008-03-01
We address the persistence and stability of three-dimensional vortex configurations in the discrete nonlinear Schrödinger equation and develop a symbolic package based on Wolfram’s MATHEMATICA for computations of the Lyapunov-Schmidt reduction method. The Lyapunov-Schmidt reduction method is a theoretical tool which enables us to study continuations and terminations of the discrete vortices for small coupling between lattice nodes as well as the spectral stability of the persistent configurations. The method was developed earlier in the context of the two-dimensional lattice and applied to the onsite and offsite configurations (called the vortex cross and the vortex cell) by using semianalytical computations [D.E. Pelinovsky, P.G. Kevrekidis, D. Frantzeskakis, Physica D 212 (2005) 20-53; P.G. Kevrekidis, D.E. Pelinovsky, Proc. R. Soc. A 462 (2006) 2671-2694]. The present treatment develops a full symbolic computational package which takes a desired waveform at the anticontinuum limit of uncoupled sites, performs a required number of Lyapunov-Schmidt reductions and outputs the predictions on whether the configuration persists, for finite coupling, in the three-dimensional lattice and whether it is stable or unstable. It also provides approximations for the eigenvalues of the linearized stability problem. We report a number of applications of the algorithm to important multisite three-dimensional configurations, such as the simple cube, the double cross and the diamond. For each configuration, we identify exactly one solution, which is stable for small coupling between lattice nodes.
Li, Nan; Wang, Junzheng
2016-03-01
A highly efficient Synchronous Dynamic Random Access Memory (SDRAM) controller supporting variable-length burst access and batch process for discrete reads is proposed in this paper. Based on the Principle of Locality, command First In First Out (FIFO) and address range detector are designed within this controller to accelerate its responses to discrete read requests, which dramatically improves the average Effective Bus Utilization Ratio (EBUR) of SDRAM. Our controller is finally verified by driving the Micron 256-Mb SDRAM MT48LC16M16A2. Successful simulation and verification results show that our controller exhibits much higher EBUR than do most existing designs in case of discrete reads.
New high-Q discrete-time LC bandpass filter design with center frequency broadband tuning
El Oualkadi, Ahmed; Paillot, Jean-Marie; Allam, Rachid
2006-01-01
International audience; Discrete-time switched-capacitor filters have been in wide-spread used for a few years, for the realization of stable, accurate and high quality filters. This paper describes the design of a new 8-path pseudo switched capacitor LC bandpass filter and its command circuit made up by a ring voltage controlled oscillator (VCO) with 'XOR' gates. The proposed architecture presents the possibility of tuning over a frequency broadband allowing to sweep different channels with ...
Wu, Guo-Cheng; Baleanu, Dumitru; Zeng, Sheng-Da
2018-04-01
This study investigates finite-time stability of Caputo delta fractional difference equations. A generalized Gronwall inequality is given on a finite time domain. A finite-time stability criterion is proposed for fractional differential equations. Then the idea is extended to the discrete fractional case. A linear fractional difference equation with constant delays is considered and finite-time stable conditions are provided. One example is numerically illustrated to support the theoretical result.
Kylling, A.
1991-01-01
The transfer equations for normal waves in finite, inhomogeneous and plane-parallel magnetoactive media are solved using the discrete ordinate method. The physical process of absorption, emission, and multiple scattering are accounted for, and the medium may be forced both at the top and bottom boundary by anisotropic radiation as well as by internal anisotropic sources. The computational procedure is numerically stable for arbitrarily large optical depths, and the computer time is independent of optical thickness.
Marginally Stable Nuclear Burning
Strohmayer, Tod E.; Altamirano, D.
2012-01-01
Thermonuclear X-ray bursts result from unstable nuclear burning of the material accreted on neutron stars in some low mass X-ray binaries (LMXBs). Theory predicts that close to the boundary of stability oscillatory burning can occur. This marginally stable regime has so far been identified in only a small number of sources. We present Rossi X-ray Timing Explorer (RXTE) observations of the bursting, high- inclination LMXB 4U 1323-619 that reveal for the first time in this source the signature of marginally stable burning. The source was observed during two successive RXTE orbits for approximately 5 ksec beginning at 10:14:01 UTC on March 28, 2011. Significant mHz quasi- periodic oscillations (QPO) at a frequency of 8.1 mHz are detected for approximately 1600 s from the beginning of the observation until the occurrence of a thermonuclear X-ray burst at 10:42:22 UTC. The mHz oscillations are not detected following the X-ray burst. The average fractional rms amplitude of the mHz QPOs is 6.4% (3 - 20 keV), and the amplitude increases to about 8% below 10 keV.This phenomenology is strikingly similar to that seen in the LMXB 4U 1636-53. Indeed, the frequency of the mHz QPOs in 4U 1323-619 prior to the X-ray burst is very similar to the transition frequency between mHz QPO and bursts found in 4U 1636-53 by Altamirano et al. (2008). These results strongly suggest that the observed QPOs in 4U 1323-619 are, like those in 4U 1636-53, due to marginally stable nuclear burning. We also explore the dependence of the energy spectrum on the oscillation phase, and we place the present observations within the context of the spectral evolution of the accretion-powered flux from the source.
Vertical discretization with finite elements for a global hydrostatic model on the cubed sphere
Yi, Tae-Hyeong; Park, Ja-Rin
2017-06-01
A formulation of Galerkin finite element with basis-spline functions on a hybrid sigma-pressure coordinate is presented to discretize the vertical terms of global Eulerian hydrostatic equations employed in a numerical weather prediction system, which is horizontally discretized with high-order spectral elements on a cubed sphere grid. This replaces the vertical discretization of conventional central finite difference that is first-order accurate in non-uniform grids and causes numerical instability in advection-dominant flows. Therefore, a model remains in the framework of Galerkin finite elements for both the horizontal and vertical spatial terms. The basis-spline functions, obtained from the de-Boor algorithm, are employed to derive both the vertical derivative and integral operators, since Eulerian advection terms are involved. These operators are used to discretize the vertical terms of the prognostic and diagnostic equations. To verify the vertical discretization schemes and compare their performance, various two- and three-dimensional idealized cases and a hindcast case with full physics are performed in terms of accuracy and stability. It was shown that the vertical finite element with the cubic basis-spline function is more accurate and stable than that of the vertical finite difference, as indicated by faster residual convergence, fewer statistical errors, and reduction in computational mode. This leads to the general conclusion that the overall performance of a global hydrostatic model might be significantly improved with the vertical finite element.
Osada, Hirofumi; Osada, Shota
2018-01-01
We prove tail triviality of determinantal point processes μ on continuous spaces. Tail triviality has been proved for such processes only on discrete spaces, and hence we have generalized the result to continuous spaces. To do this, we construct tree representations, that is, discrete approximations of determinantal point processes enjoying a determinantal structure. There are many interesting examples of determinantal point processes on continuous spaces such as zero points of the hyperbolic Gaussian analytic function with Bergman kernel, and the thermodynamic limit of eigenvalues of Gaussian random matrices for Sine_2 , Airy_2 , Bessel_2 , and Ginibre point processes. Our main theorem proves all these point processes are tail trivial.
Discrete Feature Model (DFM) User Documentation
International Nuclear Information System (INIS)
Geier, Joel
2008-06-01
This manual describes the Discrete-Feature Model (DFM) software package for modelling groundwater flow and solute transport in networks of discrete features. A discrete-feature conceptual model represents fractures and other water-conducting features around a repository as discrete conductors surrounded by a rock matrix which is usually treated as impermeable. This approximation may be valid for crystalline rocks such as granite or basalt, which have very low permeability if macroscopic fractures are excluded. A discrete feature is any entity that can conduct water and permit solute transport through bedrock, and can be reasonably represented as a piecewise-planar conductor. Examples of such entities may include individual natural fractures (joints or faults), fracture zones, and disturbed-zone features around tunnels (e.g. blasting-induced fractures or stress-concentration induced 'onion skin' fractures around underground openings). In a more abstract sense, the effectively discontinuous nature of pathways through fractured crystalline bedrock may be idealized as discrete, equivalent transmissive features that reproduce large-scale observations, even if the details of connective paths (and unconnected domains) are not precisely known. A discrete-feature model explicitly represents the fundamentally discontinuous and irregularly connected nature of systems of such systems, by constraining flow and transport to occur only within such features and their intersections. Pathways for flow and solute transport in this conceptualization are a consequence not just of the boundary conditions and hydrologic properties (as with continuum models), but also the irregularity of connections between conductive/transmissive features. The DFM software package described here is an extensible code for investigating problems of flow and transport in geological (natural or human-altered) systems that can be characterized effectively in terms of discrete features. With this software, the
Discrete Feature Model (DFM) User Documentation
Energy Technology Data Exchange (ETDEWEB)
Geier, Joel (Clearwater Hardrock Consulting, Corvallis, OR (United States))
2008-06-15
This manual describes the Discrete-Feature Model (DFM) software package for modelling groundwater flow and solute transport in networks of discrete features. A discrete-feature conceptual model represents fractures and other water-conducting features around a repository as discrete conductors surrounded by a rock matrix which is usually treated as impermeable. This approximation may be valid for crystalline rocks such as granite or basalt, which have very low permeability if macroscopic fractures are excluded. A discrete feature is any entity that can conduct water and permit solute transport through bedrock, and can be reasonably represented as a piecewise-planar conductor. Examples of such entities may include individual natural fractures (joints or faults), fracture zones, and disturbed-zone features around tunnels (e.g. blasting-induced fractures or stress-concentration induced 'onion skin' fractures around underground openings). In a more abstract sense, the effectively discontinuous nature of pathways through fractured crystalline bedrock may be idealized as discrete, equivalent transmissive features that reproduce large-scale observations, even if the details of connective paths (and unconnected domains) are not precisely known. A discrete-feature model explicitly represents the fundamentally discontinuous and irregularly connected nature of systems of such systems, by constraining flow and transport to occur only within such features and their intersections. Pathways for flow and solute transport in this conceptualization are a consequence not just of the boundary conditions and hydrologic properties (as with continuum models), but also the irregularity of connections between conductive/transmissive features. The DFM software package described here is an extensible code for investigating problems of flow and transport in geological (natural or human-altered) systems that can be characterized effectively in terms of discrete features. With this
Convergence of posteriors for discretized log Gaussian Cox processes
DEFF Research Database (Denmark)
Waagepetersen, Rasmus Plenge
2004-01-01
In Markov chain Monte Carlo posterior computation for log Gaussian Cox processes (LGCPs) a discretization of the continuously indexed Gaussian field is required. It is demonstrated that approximate posterior expectations computed from discretized LGCPs converge to the exact posterior expectations...... when the cell sizes of the discretization tends to zero. The effect of discretization is studied in a data example....
Continuum limit of discrete Sommerfeld problems on square lattice
Indian Academy of Sciences (India)
A low-frequency approximation of the discrete Sommerfeld diffraction problems, involving the scattering of a time harmonic lattice wave incident on square lattice by a discrete Dirichlet or a discrete Neumann half-plane, is investigated. It is established that the exact solution of the discrete model converges to the solution of ...
Positivity for Convective Semi-discretizations
Fekete, Imre
2017-04-19
We propose a technique for investigating stability properties like positivity and forward invariance of an interval for method-of-lines discretizations, and apply the technique to study positivity preservation for a class of TVD semi-discretizations of 1D scalar hyperbolic conservation laws. This technique is a generalization of the approach suggested in Khalsaraei (J Comput Appl Math 235(1): 137–143, 2010). We give more relaxed conditions on the time-step for positivity preservation for slope-limited semi-discretizations integrated in time with explicit Runge–Kutta methods. We show that the step-size restrictions derived are sharp in a certain sense, and that many higher-order explicit Runge–Kutta methods, including the classical 4th-order method and all non-confluent methods with a negative Butcher coefficient, cannot generally maintain positivity for these semi-discretizations under any positive step size. We also apply the proposed technique to centered finite difference discretizations of scalar hyperbolic and parabolic problems.
Discrete Localized States and Localization Dynamics in Discrete Nonlinear Schrödinger Equations
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Gaididei, Yu.B.; Mezentsev, V.K.
1996-01-01
Dynamics of two-dimensional discrete structures is studied in the framework of the generalized two-dimensional discrete nonlinear Schrodinger equation. The nonlinear coupling in the form of the Ablowitz-Ladik nonlinearity is taken into account. Stability properties of the stationary solutions...
Modeling discrete time-to-event data
Tutz, Gerhard
2016-01-01
This book focuses on statistical methods for the analysis of discrete failure times. Failure time analysis is one of the most important fields in statistical research, with applications affecting a wide range of disciplines, in particular, demography, econometrics, epidemiology and clinical research. Although there are a large variety of statistical methods for failure time analysis, many techniques are designed for failure times that are measured on a continuous scale. In empirical studies, however, failure times are often discrete, either because they have been measured in intervals (e.g., quarterly or yearly) or because they have been rounded or grouped. The book covers well-established methods like life-table analysis and discrete hazard regression models, but also introduces state-of-the art techniques for model evaluation, nonparametric estimation and variable selection. Throughout, the methods are illustrated by real life applications, and relationships to survival analysis in continuous time are expla...
Designing perturbative metamaterials from discrete models.
Matlack, Kathryn H; Serra-Garcia, Marc; Palermo, Antonio; Huber, Sebastian D; Daraio, Chiara
2018-04-01
Identifying material geometries that lead to metamaterials with desired functionalities presents a challenge for the field. Discrete, or reduced-order, models provide a concise description of complex phenomena, such as negative refraction, or topological surface states; therefore, the combination of geometric building blocks to replicate discrete models presenting the desired features represents a promising approach. However, there is no reliable way to solve such an inverse problem. Here, we introduce 'perturbative metamaterials', a class of metamaterials consisting of weakly interacting unit cells. The weak interaction allows us to associate each element of the discrete model with individual geometric features of the metamaterial, thereby enabling a systematic design process. We demonstrate our approach by designing two-dimensional elastic metamaterials that realize Veselago lenses, zero-dispersion bands and topological surface phonons. While our selected examples are within the mechanical domain, the same design principle can be applied to acoustic, thermal and photonic metamaterials composed of weakly interacting unit cells.
Symmetric, discrete fractional splines and Gabor systems
DEFF Research Database (Denmark)
Søndergaard, Peter Lempel
2006-01-01
In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing the continu......In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing...... the continuous splines, and one is a truly finite, discrete construction. We discuss the properties of these splines and their usefulness as windows for Gabor frames and Wilson bases....
The ultimatum game: Discrete vs. continuous offers
Dishon-Berkovits, Miriam; Berkovits, Richard
2014-09-01
In many experimental setups in social-sciences, psychology and economy the subjects are requested to accept or dispense monetary compensation which is usually given in discrete units. Using computer and mathematical modeling we show that in the framework of studying the dynamics of acceptance of proposals in the ultimatum game, the long time dynamics of acceptance of offers in the game are completely different for discrete vs. continuous offers. For discrete values the dynamics follow an exponential behavior. However, for continuous offers the dynamics are described by a power-law. This is shown using an agent based computer simulation as well as by utilizing an analytical solution of a mean-field equation describing the model. These findings have implications to the design and interpretation of socio-economical experiments beyond the ultimatum game.
Is Fitts' law continuous in discrete aiming?
Directory of Open Access Journals (Sweden)
Rita Sleimen-Malkoun
Full Text Available The lawful continuous linear relation between movement time and task difficulty (i.e., index of difficulty; ID in a goal-directed rapid aiming task (Fitts' law has been recently challenged in reciprocal performance. Specifically, a discontinuity was observed at critical ID and was attributed to a transition between two distinct dynamic regimes that occurs with increasing difficulty. In the present paper, we show that such a discontinuity is also present in discrete aiming when ID is manipulated via target width (experiment 1 but not via target distance (experiment 2. Fitts' law's discontinuity appears, therefore, to be a suitable indicator of the underlying functional adaptations of the neuro-muscular-skeletal system to task properties/requirements, independently of reciprocal or discrete nature of the task. These findings open new perspectives to the study of dynamic regimes involved in discrete aiming and sensori-motor mechanisms underlying the speed-accuracy trade-off.
Euler-Poincare reduction for discrete field theories
International Nuclear Information System (INIS)
Vankerschaver, Joris
2007-01-01
In this note, we develop a theory of Euler-Poincare reduction for discrete Lagrangian field theories. We introduce the concept of Euler-Poincare equations for discrete field theories, as well as a natural extension of the Moser-Veselov scheme, and show that both are equivalent. The resulting discrete field equations are interpreted in terms of discrete differential geometry. An application to the theory of discrete harmonic mappings is also briefly discussed
Thinning, photonic beamsplitting, and a general discrete entropy power inequality
Guha, Saikat; Shapiro, Jeffrey H.; Sanchez, Raul Garcia-Patron
2016-01-01
Many partially-successful attempts have been made to find the most natural discrete-variable version of Shannon's entropy power inequality (EPI). We develop an axiomatic framework from which we deduce the natural form of a discrete-variable EPI and an associated entropic monotonicity in a discrete-variable central limit theorem. In this discrete EPI, the geometric distribution, which has the maximum entropy among all discrete distributions with a given mean, assumes a role analogous to the Ga...
Cortical Neural Computation by Discrete Results Hypothesis.
Castejon, Carlos; Nuñez, Angel
2016-01-01
One of the most challenging problems we face in neuroscience is to understand how the cortex performs computations. There is increasing evidence that the power of the cortical processing is produced by populations of neurons forming dynamic neuronal ensembles. Theoretical proposals and multineuronal experimental studies have revealed that ensembles of neurons can form emergent functional units. However, how these ensembles are implicated in cortical computations is still a mystery. Although cell ensembles have been associated with brain rhythms, the functional interaction remains largely unclear. It is still unknown how spatially distributed neuronal activity can be temporally integrated to contribute to cortical computations. A theoretical explanation integrating spatial and temporal aspects of cortical processing is still lacking. In this Hypothesis and Theory article, we propose a new functional theoretical framework to explain the computational roles of these ensembles in cortical processing. We suggest that complex neural computations underlying cortical processing could be temporally discrete and that sensory information would need to be quantized to be computed by the cerebral cortex. Accordingly, we propose that cortical processing is produced by the computation of discrete spatio-temporal functional units that we have called "Discrete Results" (Discrete Results Hypothesis). This hypothesis represents a novel functional mechanism by which information processing is computed in the cortex. Furthermore, we propose that precise dynamic sequences of "Discrete Results" is the mechanism used by the cortex to extract, code, memorize and transmit neural information. The novel "Discrete Results" concept has the ability to match the spatial and temporal aspects of cortical processing. We discuss the possible neural underpinnings of these functional computational units and describe the empirical evidence supporting our hypothesis. We propose that fast-spiking (FS
Discrete quantum geometries and their effective dimension
International Nuclear Information System (INIS)
Thuerigen, Johannes
2015-01-01
In several approaches towards a quantum theory of gravity, such as group field theory and loop quantum gravity, quantum states and histories of the geometric degrees of freedom turn out to be based on discrete spacetime. The most pressing issue is then how the smooth geometries of general relativity, expressed in terms of suitable geometric observables, arise from such discrete quantum geometries in some semiclassical and continuum limit. In this thesis I tackle the question of suitable observables focusing on the effective dimension of discrete quantum geometries. For this purpose I give a purely combinatorial description of the discrete structures which these geometries have support on. As a side topic, this allows to present an extension of group field theory to cover the combinatorially larger kinematical state space of loop quantum gravity. Moreover, I introduce a discrete calculus for fields on such fundamentally discrete geometries with a particular focus on the Laplacian. This permits to define the effective-dimension observables for quantum geometries. Analysing various classes of quantum geometries, I find as a general result that the spectral dimension is more sensitive to the underlying combinatorial structure than to the details of the additional geometric data thereon. Semiclassical states in loop quantum gravity approximate the classical geometries they are peaking on rather well and there are no indications for stronger quantum effects. On the other hand, in the context of a more general model of states which are superposition over a large number of complexes, based on analytic solutions, there is a flow of the spectral dimension from the topological dimension d on low energy scales to a real number between 0 and d on high energy scales. In the particular case of 1 these results allow to understand the quantum geometry as effectively fractal.
A parallel approach to the stable marriage problem
DEFF Research Database (Denmark)
Larsen, Jesper
1997-01-01
This paper describes two parallel algorithms for the stable marriage problem implemented on a MIMD parallel computer. The algorithms are tested against sequential algorithms on randomly generated and worst-case instances. The results clearly show that the combination fo a very simple problem...... and a commercial MIMD system results in parallel algorithms which are not competitive with sequential algorithms wrt. practical performance. 1 Introduction In 1962 the Stable Marriage Problem was....
Digital and discrete geometry theory and algorithms
Chen, Li
2014-01-01
This book provides comprehensive coverage of the modern methods for geometric problems in the computing sciences. It also covers concurrent topics in data sciences including geometric processing, manifold learning, Google search, cloud data, and R-tree for wireless networks and BigData.The author investigates digital geometry and its related constructive methods in discrete geometry, offering detailed methods and algorithms. The book is divided into five sections: basic geometry; digital curves, surfaces and manifolds; discretely represented objects; geometric computation and processing; and a
Hybrid Discrete-Continuous Markov Decision Processes
Feng, Zhengzhu; Dearden, Richard; Meuleau, Nicholas; Washington, Rich
2003-01-01
This paper proposes a Markov decision process (MDP) model that features both discrete and continuous state variables. We extend previous work by Boyan and Littman on the mono-dimensional time-dependent MDP to multiple dimensions. We present the principle of lazy discretization, and piecewise constant and linear approximations of the model. Having to deal with several continuous dimensions raises several new problems that require new solutions. In the (piecewise) linear case, we use techniques from partially- observable MDPs (POMDPS) to represent value functions as sets of linear functions attached to different partitions of the state space.
Logic and discrete mathematics a concise introduction
Conradie, Willem
2015-01-01
A concise yet rigorous introduction to logic and discrete mathematics. This book features a unique combination of comprehensive coverage of logic with a solid exposition of the most important fields of discrete mathematics, presenting material that has been tested and refined by the authors in university courses taught over more than a decade. The chapters on logic - propositional and first-order - provide a robust toolkit for logical reasoning, emphasizing the conceptual understanding of the language and the semantics of classical logic as well as practical applications through the easy
Synchronization Of Parallel Discrete Event Simulations
Steinman, Jeffrey S.
1992-01-01
Adaptive, parallel, discrete-event-simulation-synchronization algorithm, Breathing Time Buckets, developed in Synchronous Parallel Environment for Emulation and Discrete Event Simulation (SPEEDES) operating system. Algorithm allows parallel simulations to process events optimistically in fluctuating time cycles that naturally adapt while simulation in progress. Combines best of optimistic and conservative synchronization strategies while avoiding major disadvantages. Algorithm processes events optimistically in time cycles adapting while simulation in progress. Well suited for modeling communication networks, for large-scale war games, for simulated flights of aircraft, for simulations of computer equipment, for mathematical modeling, for interactive engineering simulations, and for depictions of flows of information.
Efficient discrete Gabor functions for robot vision
Weiman, Carl F. R.
1994-03-01
A new discrete Gabor function provides subpixel resolution of phase while overcoming many of the computational burdens of current approaches to Gabor function implementation. Applications include hyperacuity measurement of binocular disparity and optic flow for stereo vision. Convolution is avoided by exploiting band-pass to subsample the image plane. A general purpose front end processor for robot vision, based on a wavelet interpretation of this discrete Gabor function, can be constructed by tessellating and pyramiding the elementary filter. Computational efficiency opens the door to real-time implementation which mimics many properties of the simple and complex cells in the visual cortex.
Modeling and simulation of discrete event systems
Choi, Byoung Kyu
2013-01-01
Computer modeling and simulation (M&S) allows engineers to study and analyze complex systems. Discrete-event system (DES)-M&S is used in modern management, industrial engineering, computer science, and the military. As computer speeds and memory capacity increase, so DES-M&S tools become more powerful and more widely used in solving real-life problems. Based on over 20 years of evolution within a classroom environment, as well as on decades-long experience in developing simulation-based solutions for high-tech industries, Modeling and Simulation of Discrete-Event Systems is the only book on
DEFF Research Database (Denmark)
Iskhakov, Fedor; Jørgensen, Thomas H.; Rust, John
2017-01-01
We present a fast and accurate computational method for solving and estimating a class of dynamic programming models with discrete and continuous choice variables. The solution method we develop for structural estimation extends the endogenous grid-point method (EGM) to discrete-continuous (DC...... taste shocks that are typically interpreted as “unobserved state variables” in structural econometric applications, or serve as “random noise” to smooth out kinks in the value functions in numerical applications. We present Monte Carlo experiments that demonstrate the reliability and efficiency......) problems. Discrete choices can lead to kinks in the value functions and discontinuities in the optimal policy rules, greatly complicating the solution of the model. We show how these problems are ameliorated in the presence of additive choice-specific independent and identically distributed extreme value...
Identifying the most likely contributors to a Y-STR mixture using the discrete Laplace method
DEFF Research Database (Denmark)
Andersen, Mikkel Meyer; Eriksen, Poul Svante; Mogensen, Helle Smidt
2015-01-01
demonstrate how the discrete Laplace method can be used to separate a two person Y-STR mixture, where the Y-STR profiles of the true contributors are not present in the reference dataset, which is often the case for Y-STR profiles in real case work. We also briefly discuss how to calculate the weight...... of the number of loci. For each of these datasets, an out of sample simulation study was performed: A total of 550 mixtures were composed by randomly sampling two haplotypes, h1 and h2, from the dataset. We then used the discrete Laplace method on the remaining data (excluding h1 and h2) to rank the contributor...... or less depending on the dataset and how the discrete Laplace model was chosen. Y-STR mixtures with many loci are difficult to separate, but even haplotypes with 21 Y-STR loci can be separated....
Discrete shear-transformation-zone plasticity modeling of notched bars
Kondori, Babak; Amine Benzerga, A.; Needleman, Alan
2018-02-01
Plane strain tension analyses of un-notched and notched bars are carried out using discrete shear transformation zone plasticity. In this framework, the carriers of plastic deformation are shear transformation zones (STZs) which are modeled as Eshelby inclusions. Superposition is used to represent a boundary value problem solution in terms of discretely modeled Eshelby inclusions, given analytically for an infinite elastic medium, and an image solution that enforces the prescribed boundary conditions. The image problem is a standard linear elastic boundary value problem that is solved by the finite element method. Potential STZ activation sites are randomly distributed in the bars and constitutive relations are specified for their evolution. Results are presented for un-notched bars, for bars with blunt notches and for bars with sharp notches. The computed stress-strain curves are serrated with the magnitude of the associated stress-drops depending on bar size, notch acuity and STZ evolution. Cooperative deformation bands (shear bands) emerge upon straining and, in some cases, high stress levels occur within the bands. Effects of specimen geometry and size on the stress-strain curves are explored. Depending on STZ kinetics, notch strengthening, notch insensitivity or notch weakening are obtained. The analyses provide a rationale for some conflicting findings regarding notch effects on the mechanical response of metallic glasses.
Directory of Open Access Journals (Sweden)
Yury Gutsalenko
2010-06-01
Full Text Available The paper generalizes on the one hand theory of kinematic-geometrical simulation of grinding processes by means of tools with working part as binding matrix with abrasive grains located in it in random manner, for example diamond grains, and on the other hand practical performance of combined grinding process, based on introduction of additional energy as electric discharges and called by the organization-developer (Kharkov Polytechnic Institute «diamond-spark grinding» as applied to processing by means of diamond wheel. Implementation of diamond-spark grinding technologies on the basis of developed generalized theoretical approach allows to use the tool with prescribed tool-life, moreover to make the most efficient use of it up to full exhausting of tool-life, determined by diamond-bearing thickness. Development is directed forward computer-aided manufacturing.
Hybrid discrete choice models: Gained insights versus increasing effort
International Nuclear Information System (INIS)
Mariel, Petr; Meyerhoff, Jürgen
2016-01-01
Hybrid choice models expand the standard models in discrete choice modelling by incorporating psychological factors as latent variables. They could therefore provide further insights into choice processes and underlying taste heterogeneity but the costs of estimating these models often significantly increase. This paper aims at comparing the results from a hybrid choice model and a classical random parameter logit. Point of departure for this analysis is whether researchers and practitioners should add hybrid choice models to their suite of models routinely estimated. Our comparison reveals, in line with the few prior studies, that hybrid models gain in efficiency by the inclusion of additional information. The use of one of the two proposed approaches, however, depends on the objective of the analysis. If disentangling preference heterogeneity is most important, hybrid model seems to be preferable. If the focus is on predictive power, a standard random parameter logit model might be the better choice. Finally, we give recommendations for an adequate use of hybrid choice models based on known principles of elementary scientific inference. - Highlights: • The paper compares performance of a Hybrid Choice Model (HCM) and a classical Random Parameter Logit (RPL) model. • The HCM indeed provides insights regarding preference heterogeneity not gained from the RPL. • The RPL has similar predictive power as the HCM in our data. • The costs of estimating HCM seem to be justified when learning more on taste heterogeneity is a major study objective.
Hybrid discrete choice models: Gained insights versus increasing effort
Energy Technology Data Exchange (ETDEWEB)
Mariel, Petr, E-mail: petr.mariel@ehu.es [UPV/EHU, Economía Aplicada III, Avda. Lehendakari Aguire, 83, 48015 Bilbao (Spain); Meyerhoff, Jürgen [Institute for Landscape Architecture and Environmental Planning, Technical University of Berlin, D-10623 Berlin, Germany and The Kiel Institute for the World Economy, Duesternbrooker Weg 120, 24105 Kiel (Germany)
2016-10-15
Hybrid choice models expand the standard models in discrete choice modelling by incorporating psychological factors as latent variables. They could therefore provide further insights into choice processes and underlying taste heterogeneity but the costs of estimating these models often significantly increase. This paper aims at comparing the results from a hybrid choice model and a classical random parameter logit. Point of departure for this analysis is whether researchers and practitioners should add hybrid choice models to their suite of models routinely estimated. Our comparison reveals, in line with the few prior studies, that hybrid models gain in efficiency by the inclusion of additional information. The use of one of the two proposed approaches, however, depends on the objective of the analysis. If disentangling preference heterogeneity is most important, hybrid model seems to be preferable. If the focus is on predictive power, a standard random parameter logit model might be the better choice. Finally, we give recommendations for an adequate use of hybrid choice models based on known principles of elementary scientific inference. - Highlights: • The paper compares performance of a Hybrid Choice Model (HCM) and a classical Random Parameter Logit (RPL) model. • The HCM indeed provides insights regarding preference heterogeneity not gained from the RPL. • The RPL has similar predictive power as the HCM in our data. • The costs of estimating HCM seem to be justified when learning more on taste heterogeneity is a major study objective.
Stochastic effects in a discretized kinetic model of economic exchange
Bertotti, M. L.; Chattopadhyay, A. K.; Modanese, G.
2017-04-01
Linear stochastic models and discretized kinetic theory are two complementary analytical techniques used for the investigation of complex systems of economic interactions. The former employ Langevin equations, with an emphasis on stock trade; the latter is based on systems of ordinary differential equations and is better suited for the description of binary interactions, taxation and welfare redistribution. We propose a new framework which establishes a connection between the two approaches by introducing random fluctuations into the kinetic model based on Langevin and Fokker-Planck formalisms. Numerical simulations of the resulting model indicate positive correlations between the Gini index and the total wealth, that suggest a growing inequality with increasing income. Further analysis shows, in the presence of a conserved total wealth, a simultaneous decrease in inequality as social mobility increases, in conformity with economic data.
Pseudo-random number generator based on asymptotic deterministic randomness
International Nuclear Information System (INIS)
Wang Kai; Pei Wenjiang; Xia Haishan; Cheung Yiuming
2008-01-01
A novel approach to generate the pseudorandom-bit sequence from the asymptotic deterministic randomness system is proposed in this Letter. We study the characteristic of multi-value correspondence of the asymptotic deterministic randomness constructed by the piecewise linear map and the noninvertible nonlinearity transform, and then give the discretized systems in the finite digitized state space. The statistic characteristics of the asymptotic deterministic randomness are investigated numerically, such as stationary probability density function and random-like behavior. Furthermore, we analyze the dynamics of the symbolic sequence. Both theoretical and experimental results show that the symbolic sequence of the asymptotic deterministic randomness possesses very good cryptographic properties, which improve the security of chaos based PRBGs and increase the resistance against entropy attacks and symbolic dynamics attacks
Pseudo-random number generator based on asymptotic deterministic randomness
Wang, Kai; Pei, Wenjiang; Xia, Haishan; Cheung, Yiu-ming
2008-06-01
A novel approach to generate the pseudorandom-bit sequence from the asymptotic deterministic randomness system is proposed in this Letter. We study the characteristic of multi-value correspondence of the asymptotic deterministic randomness constructed by the piecewise linear map and the noninvertible nonlinearity transform, and then give the discretized systems in the finite digitized state space. The statistic characteristics of the asymptotic deterministic randomness are investigated numerically, such as stationary probability density function and random-like behavior. Furthermore, we analyze the dynamics of the symbolic sequence. Both theoretical and experimental results show that the symbolic sequence of the asymptotic deterministic randomness possesses very good cryptographic properties, which improve the security of chaos based PRBGs and increase the resistance against entropy attacks and symbolic dynamics attacks.
Radiation forces in the discrete dipole approximation
Hoekstra, A.G.; Frijlink, M.O.; Waters, L.B.F.M.; Sloot, P.M.A.
2001-01-01
The theory of the discrete-dipole approximation (DDA) for light scattering is extended to allow for the calculation of radiation forces on each dipole in the DDA model. Starting with the theory of Draine and Weingartner [Astrophys. J. 470, 551 (1996)] we derive an expression for the radiation force
Discrete objects, splitting closure and connectedness | Castellini ...
African Journals Online (AJOL)
Notions of discrete and indiscrete classes with respect to a closure operator are introduced and studied. These notions are strongly related to splitting and cosplitting closure operators. By linking the above concepts, two Galois connections arise whose composition provides a third Galois connection that can be used as a ...
DISCRETE ELEMENT MODELLING OF THE COMPRESSIVE ...
African Journals Online (AJOL)
Having developed and validated a code based on the Discrete Element Method principle with physical experiments the code was used to study and predict the behaviour (parametric changes) during compression of four bulk systems of particulates with the properties of canola seed, palm kernel and soyabean. The porosity ...
Discrete elements in structural concrete design
Blaauwendraad, J.; Hoogenboom, P.C.J.
1997-01-01
In the sixties Prof. J. Witteveen introduced a discrete model for the elastic analysis of slabs (Heron 1966). This article presents a similar approach for the design of reinforced concrete walls and deep beams, with holes or otherwise. The model – which is called stringer-panel model – combines the
Discretization Based on Entropy and Multiple Scanning
Directory of Open Access Journals (Sweden)
Jerzy W. Grzymala-Busse
2013-04-01
Full Text Available In this paper we present entropy driven methodology for discretization. Recently, the original entropy based discretization was enhanced by including two options of selecting the best numerical attribute. In one option, Dominant Attribute, an attribute with the smallest conditional entropy of the concept given the attribute is selected for discretization and then the best cut point is determined. In the second option, Multiple Scanning, all attributes are scanned a number of times, and at the same time the best cut points are selected for all attributes. The results of experiments on 17 benchmark data sets, including large data sets, with 175 attributes or 25,931 cases, are presented. For comparison, the results of experiments on the same data sets using the global versions of well-known discretization methods of Equal Interval Width and Equal Frequency per Interval are also included. The entropy driven technique enhanced both of these methods by converting them into globalized methods. Results of our experiments show that the Multiple Scanning methodology is significantly better than both: Dominant Attribute and the better results of Globalized Equal Interval Width and Equal Frequency per Interval methods (using two-tailed test and 0.01 level of significance.
Discrete-Time Systems -RE-SONANCEI
Indian Academy of Sciences (India)
systems, robots, space applications, farming, biotech- nology and even medicine. The disciplines of continuous-time and discrete-time sig- nals and systems have become increasingly entwined. Without any doubt, it is advantageous to process conti- nuous-time signals by sampling them. The computer control system for a ...
Discrete structures in F-theory compactifications
Energy Technology Data Exchange (ETDEWEB)
Till, Oskar
2016-05-04
In this thesis we study global properties of F-theory compactifications on elliptically and genus-one fibered Calabi-Yau varieties. This is motivated by phenomenological considerations as well as by the need for a deeper understanding of the set of consistent F-theory vacua. The global geometric features arise from discrete and arithmetic structures in the torus fiber and can be studied in detail for fibrations over generic bases. In the case of elliptic fibrations we study the role of the torsion subgroup of the Mordell-Weil group of sections in four dimensional compactifications. We show how the existence of a torsional section restricts the admissible matter representations in the theory. This is shown to be equivalent to inducing a non-trivial fundamental group of the gauge group. Compactifying F-theory on genus-one fibrations with multisections gives rise to discrete selection rules. In field theory the discrete symmetry is a broken U(1) symmetry. In the geometry the higgsing corresponds to a conifold transition. We explain in detail the origin of the discrete symmetry from two different M-theory phases and put the result into the context of torsion homology. Finally we systematically construct consistent gauge fluxes on genus-one fibrations and show that these induce an anomaly free chiral spectrum.
Discrete control of resonant wave energy devices.
Clément, A H; Babarit, A
2012-01-28
Aiming at amplifying the energy productive motion of wave energy converters (WECs) in response to irregular sea waves, the strategies of discrete control presented here feature some major advantages over continuous control, which is known to require, for optimal operation, a bidirectional power take-off able to re-inject energy into the WEC system during parts of the oscillation cycles. Three different discrete control strategies are described: latching control, declutching control and the combination of both, which we term latched-operating-declutched control. It is shown that any of these methods can be applied with great benefit, not only to mono-resonant WEC oscillators, but also to bi-resonant and multi-resonant systems. For some of these applications, it is shown how these three discrete control strategies can be optimally defined, either by analytical solution for regular waves, or numerically, by applying the optimal command theory in irregular waves. Applied to a model of a seven degree-of-freedom system (the SEAREV WEC) to estimate its annual production on several production sites, the most efficient of these discrete control strategies was shown to double the energy production, regardless of the resource level of the site, which may be considered as a real breakthrough, rather than a marginal improvement.
About Multi-Heston SDE Discretization
Directory of Open Access Journals (Sweden)
Tiberiu Socaciu
2013-07-01
Full Text Available Abstract: in this paper we show how can estimate a financial derivative based on a support if assume for the support a Multi-Heston model.Keywords: Euler Maruyama discretization method, Monte Carlo simulation, Heston model, Double-Heston model, Multi-Heston model.
Conservation of wave action under multisymplectic discretizations
J.E. Frank (Jason)
2006-01-01
textabstractIn this paper we discuss the conservation of wave action under numerical discretization by variational and multisymplectic methods. Both the general wave action conservation defined with respect to a smooth, periodic, one-parameter ensemble of flow realizations and the specific wave
Neutrino mass and mixing with discrete symmetry
King, Stephen F.; Luhn, Christoph
2013-05-01
This is a review paper about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing matrix and the latest global fits following the Daya Bay and RENO experiments which measure the reactor angle. We then describe the simple bimaximal, tri-bimaximal and golden ratio patterns of lepton mixing and the deviations required for a non-zero reactor angle, with solar or atmospheric mixing sum rules resulting from charged lepton corrections or residual trimaximal mixing. The different types of see-saw mechanism are then reviewed as well as the sequential dominance mechanism. We then give a mini-review of finite group theory, which may be used as a discrete family symmetry broken by flavons either completely, or with different subgroups preserved in the neutrino and charged lepton sectors. These two approaches are then reviewed in detail in separate chapters including mechanisms for flavon vacuum alignment and different model building strategies that have been proposed to generate the reactor angle. We then briefly review grand unified theories (GUTs) and how they may be combined with discrete family symmetry to describe all quark and lepton masses and mixing. Finally, we discuss three model examples which combine an SU(5) GUT with the discrete family symmetries A4, S4 and Δ(96).
Enriched vibrational resonance in certain discrete systems
Indian Academy of Sciences (India)
We wish to report the occurrence of vibrational resonance in certain discrete systems like sine square map and sine circle map, in a unique fashion, comprising of multiple resonant peaks which pave the way for enrichment. As the systems of our choice are capable of exhibiting vibrational resonance behaviour unlike the ...
Discrete-time rewards model-checked
Larsen, K.G.; Andova, S.; Niebert, Peter; Hermanns, H.; Katoen, Joost P.
2003-01-01
This paper presents a model-checking approach for analyzing discrete-time Markov reward models. For this purpose, the temporal logic probabilistic CTL is extended with reward constraints. This allows to formulate complex measures – involving expected as well as accumulated rewards – in a precise and
Discrete dispersion models and their Tweedie asymptotics
DEFF Research Database (Denmark)
Jørgensen, Bent; Kokonendji, Célestin C.
2016-01-01
The paper introduce a class of two-parameter discrete dispersion models, obtained by combining convolution with a factorial tilting operation, similar to exponential dispersion models which combine convolution and exponential tilting. The equidispersed Poisson model has a special place in this ap......The paper introduce a class of two-parameter discrete dispersion models, obtained by combining convolution with a factorial tilting operation, similar to exponential dispersion models which combine convolution and exponential tilting. The equidispersed Poisson model has a special place...... in this approach, whereas several overdispersed discrete distributions, such as the Neyman Type A, Pólya-Aeppli, negative binomial and Poisson-inverse Gaussian, turn out to be Poisson-Tweedie factorial dispersion models with power dispersion functions, analogous to ordinary Tweedie exponential dispersion models...... with power variance functions. Using the factorial cumulant generating function as tool, we introduce a dilation operation as a discrete analogue of scaling, generalizing binomial thinning. The Poisson-Tweedie factorial dispersion models are closed under dilation, which in turn leads to a Poisson...
Geometric phases in discrete dynamical systems
Energy Technology Data Exchange (ETDEWEB)
Cartwright, Julyan H.E., E-mail: julyan.cartwright@csic.es [Instituto Andaluz de Ciencias de la Tierra, CSIC–Universidad de Granada, E-18100 Armilla, Granada (Spain); Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, E-18071 Granada (Spain); Piro, Nicolas, E-mail: nicolas.piro@epfl.ch [École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Piro, Oreste, E-mail: piro@imedea.uib-csic.es [Departamento de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Tuval, Idan, E-mail: ituval@imedea.uib-csic.es [Mediterranean Institute for Advanced Studies, CSIC–Universitat de les Illes Balears, E-07190 Mallorca (Spain)
2016-10-14
In order to study the behaviour of discrete dynamical systems under adiabatic cyclic variations of their parameters, we consider discrete versions of adiabatically-rotated rotators. Parallelling the studies in continuous systems, we generalize the concept of geometric phase to discrete dynamics and investigate its presence in these rotators. For the rotated sine circle map, we demonstrate an analytical relationship between the geometric phase and the rotation number of the system. For the discrete version of the rotated rotator considered by Berry, the rotated standard map, we further explore this connection as well as the role of the geometric phase at the onset of chaos. Further into the chaotic regime, we show that the geometric phase is also related to the diffusive behaviour of the dynamical variables and the Lyapunov exponent. - Highlights: • We extend the concept of geometric phase to maps. • For the rotated sine circle map, we demonstrate an analytical relationship between the geometric phase and the rotation number. • For the rotated standard map, we explore the role of the geometric phase at the onset of chaos. • We show that the geometric phase is related to the diffusive behaviour of the dynamical variables and the Lyapunov exponent.
A Note on Discrete Mathematics and Calculus.
O'Reilly, Thomas J.
1987-01-01
Much of the current literature on the topic of discrete mathematics and calculus during the first two years of an undergraduate mathematics curriculum is cited. A relationship between the recursive integration formulas and recursively defined polynomials is described. A Pascal program is included. (Author/RH)
Applied Behavior Analysis: Beyond Discrete Trial Teaching
Steege, Mark W.; Mace, F. Charles; Perry, Lora; Longenecker, Harold
2007-01-01
We discuss the problem of autism-specific special education programs representing themselves as Applied Behavior Analysis (ABA) programs when the only ABA intervention employed is Discrete Trial Teaching (DTT), and often for limited portions of the school day. Although DTT has many advantages to recommend its use, it is not well suited to teach…
Chaos in discrete fractional difference equations
Indian Academy of Sciences (India)
2016-09-07
Sep 7, 2016 ... tions in the mathematical modelling of real-world phenomena with memory effects. In the present paper, the chaotic behaviour of ... tives allow us to deal comfortably with memory effects in dynamical systems [2]. Discrete ..... House, Reading, Connecticut, USA, 2006). [6] F Mainardi, Fractional calculus and ...
Discrete groups, Mumford curves and Theta functions
Put, Marius van der
1992-01-01
A discrete group Γ given over some complete non archimedean valued field defines a curve X. The theta functions for Γ provide an analytic construction for the Jacobian variety of X. A theory of theta functions is developed with the help of currents on trees and graphs and the cohomology for Γ. In
Fair value accounting and managerial discretion
Byrne, A.; Clacher, I.; Hillier, D.; Hodgson, A.
2008-01-01
We analyse the extent to which managers exercise discretion under fair value accounting and the value relevance of these disclosures. Utilising a sample of firms that apply the UK fair value pension accounting standard, (FRS-17), we examine the main determinants of the assumptions managers use to
Discrete variable representation for singular Hamiltonians
DEFF Research Database (Denmark)
Schneider, B. I.; Nygaard, Nicolai
2004-01-01
We discuss the application of the discrete variable representation (DVR) to Schrodinger problems which involve singular Hamiltonians. Unlike recent authors who invoke transformations to rid the eigenvalue equation of singularities at the cost of added complexity, we show that an approach based...
Constructing an automorphism with discrete spectrum | Isere ...
African Journals Online (AJOL)
This work is a desire to construct an automorphism with discrete spectrum using a numerical example. We briefly discuss how some of the definitions and theorems about its behaviour can be implemented and verified numerically. While it is not intended as a complete introduction to measure theory, only the definitions ...
Discrete Mathematics Course Supported by CAS MATHEMATICA
Ivanov, O. A.; Ivanova, V. V.; Saltan, A. A.
2017-01-01
In this paper, we discuss examples of assignments for a course in discrete mathematics for undergraduate students majoring in business informatics. We consider several problems with computer-based solutions and discuss general strategies for using computers in teaching mathematics and its applications. In order to evaluate the effectiveness of our…
Cuspidal discrete series for projective hyperbolic spaces
DEFF Research Database (Denmark)
Andersen, Nils Byrial; Flensted-Jensen, Mogens
2013-01-01
Abstract. We have in [1] proposed a definition of cusp forms on semisimple symmetric spaces G/H, involving the notion of a Radon transform and a related Abel transform. For the real non-Riemannian hyperbolic spaces, we showed that there exists an infinite number of cuspidal discrete series, and a...
A dynamic discretization method for reliability inference in Dynamic Bayesian Networks
International Nuclear Information System (INIS)
Zhu, Jiandao; Collette, Matthew
2015-01-01
The material and modeling parameters that drive structural reliability analysis for marine structures are subject to a significant uncertainty. This is especially true when time-dependent degradation mechanisms such as structural fatigue cracking are considered. Through inspection and monitoring, information such as crack location and size can be obtained to improve these parameters and the corresponding reliability estimates. Dynamic Bayesian Networks (DBNs) are a powerful and flexible tool to model dynamic system behavior and update reliability and uncertainty analysis with life cycle data for problems such as fatigue cracking. However, a central challenge in using DBNs is the need to discretize certain types of continuous random variables to perform network inference while still accurately tracking low-probability failure events. Most existing discretization methods focus on getting the overall shape of the distribution correct, with less emphasis on the tail region. Therefore, a novel scheme is presented specifically to estimate the likelihood of low-probability failure events. The scheme is an iterative algorithm which dynamically partitions the discretization intervals at each iteration. Through applications to two stochastic crack-growth example problems, the algorithm is shown to be robust and accurate. Comparisons are presented between the proposed approach and existing methods for the discretization problem. - Highlights: • A dynamic discretization method is developed for low-probability events in DBNs. • The method is compared to existing approaches on two crack growth problems. • The method is shown to improve on existing methods for low-probability events
The Pairing Matrix in Discrete Electromagnetism On the Geometry of Discrete de Rham Currents
Auchmann, B
2007-01-01
We introduce pairing matrices on simplicial cell complexes in discrete electromagnetism as a means to avoid the explicit construction of a topologically dual complex. Interestingly, the Finite Element Method with first-order Whitney elements â when it is looked upon from a cell-method perspective â features pairing matrices and thus an implicitly defined dual mesh. We show that the pairing matrix can be used to construct discrete energy products. In this exercise we find that different formalisms lead to equivalent matrix representations. Discrete de Rham currents are an elegant way to subsume these geometrically equivalent but formally distinct ways of defining energy-products.
International Nuclear Information System (INIS)
Feng Baofeng; Maruno, Ken-ichi; Inoguchi, Jun-ichi; Kajiwara, Kenji; Ohta, Yasuhiro
2011-01-01
We consider integrable discretizations of some soliton equations associated with the motions of plane curves: the Wadati-Konno-Ichikawa elastic beam equation, the complex Dym equation and the short pulse equation. They are related to the modified KdV or the sine-Gordon equations by the hodograph transformations. Based on the observation that the hodograph transformations are regarded as the Euler-Lagrange transformations of the curve motions, we construct the discrete analogues of the hodograph transformations, which yield integrable discretizations of those soliton equations. (paper)
Yee, H. C.; Sweby, P. K.
1995-01-01
The global asymptotic nonlinear behavior of 1 1 explicit and implicit time discretizations for four 2 x 2 systems of first-order autonomous nonlinear ordinary differential equations (ODES) is analyzed. The objectives are to gain a basic understanding of the difference in the dynamics of numerics between the scalars and systems of nonlinear autonomous ODEs and to set a baseline global asymptotic solution behavior of these schemes for practical computations in computational fluid dynamics. We show how 'numerical' basins of attraction can complement the bifurcation diagrams in gaining more detailed global asymptotic behavior of time discretizations for nonlinear differential equations (DEs). We show how in the presence of spurious asymptotes the basins of the true stable steady states can be segmented by the basins of the spurious stable and unstable asymptotes. One major consequence of this phenomenon which is not commonly known is that this spurious behavior can result in a dramatic distortion and, in most cases, a dramatic shrinkage and segmentation of the basin of attraction of the true solution for finite time steps. Such distortion, shrinkage and segmentation of the numerical basins of attraction will occur regardless of the stability of the spurious asymptotes, and will occur for unconditionally stable implicit linear multistep methods. In other words, for the same (common) steady-state solution the associated basin of attraction of the DE might be very different from the discretized counterparts and the numerical basin of attraction can be very different from numerical method to numerical method. The results can be used as an explanation for possible causes of error, and slow convergence and nonconvergence of steady-state numerical solutions when using the time-dependent approach for nonlinear hyperbolic or parabolic PDES.
Stable Blind Deconvolution over the Reals from Additional Autocorrelations
Walk, Philipp
2017-10-22
Recently the one-dimensional time-discrete blind deconvolution problem was shown to be solvable uniquely, up to a global phase, by a semi-definite program for almost any signal, provided its autocorrelation is known. We will show in this work that under a sufficient zero separation of the corresponding signal in the $z-$domain, a stable reconstruction against additive noise is possible. Moreover, the stability constant depends on the signal dimension and on the signals magnitude of the first and last coefficients. We give an analytical expression for this constant by using spectral bounds of Vandermonde matrices.
Edgington, Eugene
2007-01-01
Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani
Infant differential behavioral responding to discrete emotions.
Walle, Eric A; Reschke, Peter J; Camras, Linda A; Campos, Joseph J
2017-10-01
Emotional communication regulates the behaviors of social partners. Research on individuals' responding to others' emotions typically compares responses to a single negative emotion compared with responses to a neutral or positive emotion. Furthermore, coding of such responses routinely measure surface level features of the behavior (e.g., approach vs. avoidance) rather than its underlying function (e.g., the goal of the approach or avoidant behavior). This investigation examined infants' responding to others' emotional displays across 5 discrete emotions: joy, sadness, fear, anger, and disgust. Specifically, 16-, 19-, and 24-month-old infants observed an adult communicate a discrete emotion toward a stimulus during a naturalistic interaction. Infants' responses were coded to capture the function of their behaviors (e.g., exploration, prosocial behavior, and security seeking). The results revealed a number of instances indicating that infants use different functional behaviors in response to discrete emotions. Differences in behaviors across emotions were clearest in the 24-month-old infants, though younger infants also demonstrated some differential use of behaviors in response to discrete emotions. This is the first comprehensive study to identify differences in how infants respond with goal-directed behaviors to discrete emotions. Additionally, the inclusion of a function-based coding scheme and interpersonal paradigms may be informative for future emotion research with children and adults. Possible developmental accounts for the observed behaviors and the benefits of coding techniques emphasizing the function of social behavior over their form are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
WORKSHOP: Stable particle motion
International Nuclear Information System (INIS)
Ruggiero, Alessandro G.
1993-01-01
Full text: Particle beam stability is crucial to any accelerator or collider, particularly big ones, such as Brookhaven's RHIC heavy ion collider and the larger SSC and LHC proton collider schemes. A workshop on the Stability of Particle Motion in Storage Rings held at Brookhaven in October dealt with the important issue of determining the short- and long-term stability of single particle motion in hadron storage rings and colliders, and explored new methods for ensuring it. In the quest for realistic environments, the imperfections of superconducting magnets and the effects of field modulation and noise were taken into account. The workshop was divided into three study groups: Short-Term Stability in storage rings, including chromatic and geometric effects and correction strategies; Long-Term Stability, including modulation and random noise effects and slow varying effects; and Methods for determining the stability of particle motion. The first two were run in parallel, but the third was attended by everyone. Each group considered analytical, computational and experimental methods, reviewing work done so far, comparing results and approaches and underlining outstanding issues. By resolving conflicts, it was possible to identify problems of common interest. The workshop reaffirmed the validity of methods proposed several years ago. Major breakthroughs have been in the rapid improvement of computer capacity and speed, in the development of more sophisticated mathematical packages, and in the introduction of more powerful analytic approaches. In a typical storage ring, a particle may be required to circulate for about a billion revolutions. While ten years ago it was only possible to predict accurately stability over about a thousand revolutions, it is now possible to predict over as many as one million turns. If this trend continues, in ten years it could become feasible to predict particle stability over the entire storage period. About ninety participants
Directory of Open Access Journals (Sweden)
Maode Yan
2008-01-01
Full Text Available This paper considers the problem of robust discrete-time sliding-mode control (DT-SMC design for a class of uncertain linear systems with time-varying delays. By applying a descriptor model transformation and Moon's inequality for bounding cross terms, a delay-dependent sufficient condition for the existence of stable sliding surface is given in terms of linear matrix inequalities (LMIs. Based on this existence condition, the synthesized sliding mode controller can guarantee the sliding-mode reaching condition of the specified discrete-time sliding surface for all admissible uncertainties and time-varying delays. An illustrative example verifies the effectiveness of the proposed method.
Directory of Open Access Journals (Sweden)
Roman Senkerik
2016-01-01
Full Text Available In this paper, evolutionary technique Differential Evolution (DE is used for the evolutionary tuning of controller parameters for the stabilization of selected discrete chaotic system, which is the two-dimensional Lozi map. The novelty of the approach is that the selected controlled discrete dissipative chaotic system is used within Chaos enhanced heuristic concept as the chaotic pseudo-random number generator to drive the mutation and crossover process in the DE. The idea was to utilize the hidden chaotic dynamics in pseudo-random sequences given by chaotic map to help Differential evolution algorithm in searching for the best controller settings for the same chaotic system. The optimizations were performed for three different required final behavior of the chaotic system, and two types of developed cost function. To confirm the robustness of presented approach, comparisons with canonical DE strategy and PSO algorithm have been performed.
Hu, Shuangwei; Lundgren, Martin; Niemi, Antti J.
2011-06-01
We develop a transfer matrix formalism to visualize the framing of discrete piecewise linear curves in three-dimensional space. Our approach is based on the concept of an intrinsically discrete curve. This enables us to more effectively describe curves that in the limit where the length of line segments vanishes approach fractal structures in lieu of continuous curves. We verify that in the case of differentiable curves the continuum limit of our discrete equation reproduces the generalized Frenet equation. In particular, we draw attention to the conceptual similarity between inflection points where the curvature vanishes and topologically stable solitons. As an application we consider folded proteins, their Hausdorff dimension is known to be fractal. We explain how to employ the orientation of Cβ carbons of amino acids along a protein backbone to introduce a preferred framing along the backbone. By analyzing the experimentally resolved fold geometries in the Protein Data Bank we observe that this Cβ framing relates intimately to the discrete Frenet framing. We also explain how inflection points (a.k.a. soliton centers) can be located in the loops and clarify their distinctive rôle in determining the loop structure of folded proteins.
Adaptive NN controller design for a class of nonlinear MIMO discrete-time systems.
Liu, Yan-Jun; Tang, Li; Tong, Shaocheng; Chen, C L Philip
2015-05-01
An adaptive neural network tracking control is studied for a class of multiple-input multiple-output (MIMO) nonlinear systems. The studied systems are in discrete-time form and the discretized dead-zone inputs are considered. In addition, the studied MIMO systems are composed of N subsystems, and each subsystem contains unknown functions and external disturbance. Due to the complicated framework of the discrete-time systems, the existence of the dead zone and the noncausal problem in discrete-time, it brings about difficulties for controlling such a class of systems. To overcome the noncausal problem, by defining the coordinate transformations, the studied systems are transformed into a special form, which is suitable for the backstepping design. The radial basis functions NNs are utilized to approximate the unknown functions of the systems. The adaptation laws and the controllers are designed based on the transformed systems. By using the Lyapunov method, it is proved that the closed-loop system is stable in the sense that the semiglobally uniformly ultimately bounded of all the signals and the tracking errors converge to a bounded compact set. The simulation examples and the comparisons with previous approaches are provided to illustrate the effectiveness of the proposed control algorithm.
Discrete symmetries in Heterotic/F-theory duality and mirror symmetry
Cvetič, Mirjam; Grassi, Antonella; Poretschkin, Maximilian
2017-06-01
We study aspects of Heterotic/F-theory duality for compactifications with Abelian discrete gauge symmetries. We consider F-theory compactifications on genus-one fibered Calabi-Yau manifolds with n-sections, associated with the Tate-Shafarevich group Z_n. Such models are obtained by studying first a specific toric set-up whose associated Heterotic vector bundle has structure group Z_n. By employing a conjectured Heterotic/F-theory mirror symmetry we construct dual geometries of these original toric models, where in the stable degeneration limit we obtain a discrete gauge symmetry of order two and three, for compactifications to six dimensions. We provide explicit constructions of mirror-pairs for symmetric examples with Z_2 and Z_3, in six dimensions. The Heterotic models with symmetric discrete symmetries are related in field theory to a Higgsing of Heterotic models with two symmetric abelian U(1) gauge factors, where due to the Stückelberg mechanism only a diagonal U(1) factor remains massless, and thus after Higgsing only a diagonal discrete symmetry of order n is present in the Heterotic models and detected via Heterotic/F-theory duality. These constructions also provide further evidence for the conjectured mirror symmetry in Heterotic/F-theory at the level of fibrations with torsional sections and those with multi-sections.
Random packing of colloids and granular matter
Wouterse, A.
2008-01-01
This thesis deals with the random packing of colloids and granular matter. A random packing is a stable disordered collection of touching particles, without long-range positional and orientational order. Experimental random packings of particles with the same shape but made of different materials
Unconditionally stable diffusion-acceleration of the transport equation
International Nuclear Information System (INIS)
Larson, E.W.
1982-01-01
The standard iterative procedure for solving fixed-source discrete-ordinates problems converges very slowly for problems in optically thick regions with scattering ratios c near unity. The diffusion-synthetic acceleration method has been proposed to make use of the fact that for this class of problems, the diffusion equation is often an accurate approximation to the transport equation. However, stability difficulties have historically hampered the implementation of this method for general transport differencing schemes. In this article we discuss a recently developed procedure for obtaining unconditionally stable diffusion-synthetic acceleration methods for various transport differencing schemes. We motivate the analysis by first discussing the exact transport equation; then we illustrate the procedure by deriving a new stable acceleration method for the linear discontinuous transport differencing scheme. We also provide some numerical results
Funaki, Tadahisa
2016-01-01
Interfaces are created to separate two distinct phases in a situation in which phase coexistence occurs. This book discusses randomly fluctuating interfaces in several different settings and from several points of view: discrete/continuum, microscopic/macroscopic, and static/dynamic theories. The following four topics in particular are dealt with in the book. Assuming that the interface is represented as a height function measured from a fixed-reference discretized hyperplane, the system is governed by the Hamiltonian of gradient of the height functions. This is a kind of effective interface model called ∇φ-interface model. The scaling limits are studied for Gaussian (or non-Gaussian) random fields with a pinning effect under a situation in which the rate functional of the corresponding large deviation principle has non-unique minimizers. Young diagrams determine decreasing interfaces, and their dynamics are introduced. The large-scale behavior of such dynamics is studied from the points of view of the hyd...
Varughese, Melvin M
2009-12-01
The traditional Kolmogorov equations treat the size of a population as a discrete random variable. A model is introduced that extends these equations to incorporate environmental variability. Difficulties with this discrete model motivate approximating the population size as a continuous random variable through the use of diffusion processes. The set of cumulants for both the population size and the environmental factors affecting the population size characterize the population-environmental system. The evolution of this set, as predicted by the diffusion approximation, closely matches the corresponding predictions for the discrete model. It is also noted that the simulation estimates of the cumulants against which the predictions of the diffusion model are checked can vary considerably between simulations - despite averaging over a large number of simulation runs. The precision of the simulation estimates-both over time and with differing cumulant order-is discussed.
Breatherlike excitations in discrete lattices with noise and nonlinear damping
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Gaididei, Yuri B.; Johansson, Magnus
1997-01-01
We discuss the stability of highly localized, ''breatherlike,'' excitations in discrete nonlinear lattices under the influence of thermal fluctuations. The particular model considered is the discrete nonlinear Schrodinger equation in the regime of high nonlinearity, where temperature effects...
Nonlinear Control and Discrete Event Systems
Meyer, George; Null, Cynthia H. (Technical Monitor)
1995-01-01
As the operation of large systems becomes ever more dependent on extensive automation, the need for an effective solution to the problem of design and validation of the underlying software becomes more critical. Large systems possesses much detailed structure, typically hierarchical, and they are hybrid. Information processing at the top of the hierarchy is by means of formal logic and sentences; on the bottom it is by means of simple scalar differential equations and functions of time; and in the middle it is by an interacting mix of nonlinear multi-axis differential equations and automata, and functions of time and discrete events. The lecture will address the overall problem as it relates to flight vehicle management, describe the middle level, and offer a design approach that is based on Differential Geometry and Discrete Event Dynamic Systems Theory.
Discrete and continuous simulation theory and practice
Bandyopadhyay, Susmita
2014-01-01
When it comes to discovering glitches inherent in complex systems-be it a railway or banking, chemical production, medical, manufacturing, or inventory control system-developing a simulation of a system can identify problems with less time, effort, and disruption than it would take to employ the original. Advantageous to both academic and industrial practitioners, Discrete and Continuous Simulation: Theory and Practice offers a detailed view of simulation that is useful in several fields of study.This text concentrates on the simulation of complex systems, covering the basics in detail and exploring the diverse aspects, including continuous event simulation and optimization with simulation. It explores the connections between discrete and continuous simulation, and applies a specific focus to simulation in the supply chain and manufacturing field. It discusses the Monte Carlo simulation, which is the basic and traditional form of simulation. It addresses future trends and technologies for simulation, with par...
Integral and discrete inequalities and their applications
Qin, Yuming
2016-01-01
This book focuses on one- and multi-dimensional linear integral and discrete Gronwall-Bellman type inequalities. It provides a useful collection and systematic presentation of known and new results, as well as many applications to differential (ODE and PDE), difference, and integral equations. With this work the author fills a gap in the literature on inequalities, offering an ideal source for researchers in these topics. The present volume is part 1 of the author’s two-volume work on inequalities. Integral and discrete inequalities are a very important tool in classical analysis and play a crucial role in establishing the well-posedness of the related equations, i.e., differential, difference and integral equations.
Discrete Spectrum Reconstruction Using Integral Approximation Algorithm.
Sizikov, Valery; Sidorov, Denis
2017-07-01
An inverse problem in spectroscopy is considered. The objective is to restore the discrete spectrum from observed spectrum data, taking into account the spectrometer's line spread function. The problem is reduced to solution of a system of linear-nonlinear equations (SLNE) with respect to intensities and frequencies of the discrete spectral lines. The SLNE is linear with respect to lines' intensities and nonlinear with respect to the lines' frequencies. The integral approximation algorithm is proposed for the solution of this SLNE. The algorithm combines solution of linear integral equations with solution of a system of linear algebraic equations and avoids nonlinear equations. Numerical examples of the application of the technique, both to synthetic and experimental spectra, demonstrate the efficacy of the proposed approach in enabling an effective enhancement of the spectrometer's resolution.
Probabilistic Discrete Mixtures Colour Texture Models
Czech Academy of Sciences Publication Activity Database
Haindl, Michal; Havlíček, Vojtěch; Grim, Jiří
2008-01-01
Roč. 2008, č. 5197 (2008), s. 675-682 ISSN 0302-9743. [Iberoamerican Congress on Pattern Recognition /13./. Havana, 09.092008-12.09.2008] R&D Projects: GA AV ČR 1ET400750407; GA MŠk 1M0572; GA ČR GA102/07/1594; GA ČR GA102/08/0593 Grant - others:GA MŠk(CZ) 2C06019 Institutional research plan: CEZ:AV0Z10750506 Keywords : Discrete distribution mixtures * EM algorithm * texture modeling Subject RIV: BD - Theory of Information http://library.utia.cas.cz/separaty/2008/RO/haindl-havlicek-grim-probabilistic%20discrete%20mixtures%20colour%20texture%20models.pdf
Discrete event systems diagnosis and diagnosability
Sayed-Mouchaweh, Moamar
2014-01-01
Discrete Event Systems: Diagnosis and Diagnosability addresses the problem of fault diagnosis of Discrete Event Systems (DES). This book provides the basic techniques and approaches necessary for the design of an efficient fault diagnosis system for a wide range of modern engineering applications. The different techniques and approaches are classified according to several criteria such as: modeling tools (Automata, Petri nets) that is used to construct the model; the information (qualitative based on events occurrences and/or states outputs, quantitative based on signal processing and data analysis) that is needed to analyze and achieve the diagnosis; the decision structure (centralized, decentralized) that is required to achieve the diagnosis. The goal of this classification is to select the efficient method to achieve the fault diagnosis according to the application constraints. This book focuses on the centralized and decentralized event based diagnosis approaches using formal language and automata as mode...
Gauged discrete symmetries and proton stability
International Nuclear Information System (INIS)
Mohapatra, Rabindra N.; Ratz, Michael
2007-01-01
We discuss the results of a search for anomaly-free Abelian Z N discrete symmetries that lead to automatic R-parity conservation and prevent dangerous higher-dimensional proton decay operators in simple extensions of minimal supersymmetric extension of the standard model based on the left-right symmetric group, the Pati-Salam group and SO(10). We require that the superpotential for the models have enough structures to be able to give correct symmetry breaking to minimal supersymmetric extension of the standard model and potentially realistic fermion masses. We find viable models in each of the extensions, and for all the cases, anomaly freedom of the discrete symmetry restricts the number of generations
Finite Volumes Discretization of Topology Optimization Problems
DEFF Research Database (Denmark)
Evgrafov, Anton; Gregersen, Misha Marie; Sørensen, Mads Peter
, FVMs represent a standard method of discretization within engineering communities dealing with computational uid dy- namics, transport, and convection-reaction problems. Among various avours of FVMs, cell based approaches, where all variables are associated only with cell centers, are particularly...... computations is done using nite element methods (FEMs). Despite some limited recent eorts [1, 2], we have only started to develop our understanding of the interplay between the control in the coecients and FVMs. Recent advances in discrete functional analysis allow us to analyze convergence of FVM...... of the induced parametrization of the design space that allows optimization algorithms to eciently explore it, and the ease of integration with existing computational codes in a variety of application areas, the simplicity and eciency of sensitivity analyses|all stemming from the use of the same grid throughout...
Testing Preference Axioms in Discrete Choice experiments
DEFF Research Database (Denmark)
Hougaard, Jens Leth; Østerdal, Lars Peter; Tjur, Tue
Recent studies have tested the preference axioms of completeness and transitivity, and have detected other preference phenomena such as unstability, learning- and tiredness effects, ordering effects and dominance, in stated preference discrete choice experiments. However, it has not been explicitly...... addressed in these studies which preference models are actually being tested, and the connection between the statistical tests performed and the relevant underlying models of respondent behavior has not been explored further. This paper tries to fill that gap. We specifically analyze the meaning and role...... of the preference axioms and other preference phenomena in the context of stated preference discrete choice experiments, and examine whether or how these can be subject to meaningful (statistical) tests...
PHASE CHAOS IN THE DISCRETE KURAMOTO MODEL
DEFF Research Database (Denmark)
Maistrenko, V.; Vasylenko, A.; Maistrenko, Y.
2010-01-01
The paper describes the appearance of a novel, high-dimensional chaotic regime, called phase chaos, in a time-discrete Kuramoto model of globally coupled phase oscillators. This type of chaos is observed at small and intermediate values of the coupling strength. It arises from the nonlinear...... interaction among the oscillators, while the individual oscillators behave periodically when left uncoupled. For the four-dimensional time-discrete Kuramoto model, we outline the region of phase chaos in the parameter plane and determine the regions where phase chaos coexists with different periodic...... attractors. We also study the subcritical frequency-splitting bifurcation at the onset of desynchronization and demonstrate that the transition to phase chaos takes place via a torus destruction process....
Discrete approach to complex planar geometries
International Nuclear Information System (INIS)
Cupini, E.; De Matteis, A.
1974-01-01
Planar regions in Monte Carlo transport problems have been represented by a finite set of points with a corresponding region index for each. The simulation of particle free-flight reduces then to the simple operations necessary for scanning appropriate grid points to determine whether a region other than the starting one is encountered. When the complexity of the geometry is restricted to only some regions of the assembly examined, a mixed discrete-continuous philosophy may be adopted. By this approach, the lattice of a thermal reactor has been treated, discretizing only the central regions of the cell containing the fuel rods. Excellent agreement with experimental results has been obtained in the computation of cell parameters in the energy range from fission to thermalization through the 238 U resonance region. (U.S.)
Juxtaposed color halftoning relying on discrete lines.
Babaei, Vahid; Hersch, Roger D
2013-02-01
Most halftoning techniques allow screen dots to overlap. They rely on the assumption that the inks are transparent, i.e., the inks do not scatter a significant portion of the light back to the air. However, many special effect inks, such as metallic inks, iridescent inks, or pigmented inks, are not transparent. In order to create halftone images, halftone dots formed by such inks should be juxtaposed, i.e., printed side by side. We propose an efficient juxtaposed color halftoning technique for placing any desired number of colorant layers side by side without overlapping. The method uses a monochrome library of screen elements made of discrete lines with rational thicknesses. Discrete line juxtaposed color halftoning is performed efficiently by multiple accesses to the screen element library.
Hydraulically controlled discrete sampling from open boreholes
Harte, Philip T.
2013-01-01
Groundwater sampling from open boreholes in fractured-rock aquifers is particularly challenging because of mixing and dilution of fluid within the borehole from multiple fractures. This note presents an alternative to traditional sampling in open boreholes with packer assemblies. The alternative system called ZONFLO (zonal flow) is based on hydraulic control of borehole flow conditions. Fluid from discrete fractures zones are hydraulically isolated allowing for the collection of representative samples. In rough-faced open boreholes and formations with less competent rock, hydraulic containment may offer an attractive alternative to physical containment with packers. Preliminary test results indicate a discrete zone can be effectively hydraulically isolated from other zones within a borehole for the purpose of groundwater sampling using this new method.
Discrete PID Tuning Using Artificial Intelligence Techniques
Directory of Open Access Journals (Sweden)
Petr DOLEŽEL
2009-06-01
Full Text Available PID controllers are widely used in industry these days due to their useful properties such as simple tuning or robustness. While they are applicable to many control problems, they can perform poorly in some applications. Highly nonlinear system control with constrained manipulated variable can be mentioned as an example. The point of the paper is to string together convenient qualities of conventional PID control and progressive techniques based on Artificial Intelligence. Proposed control method should deal with even highly nonlinear systems. To be more specific, there is described new method of discrete PID controller tuning in this paper. This method tunes discrete PID controller parameters online through the use of genetic algorithm and neural model of controlled system in order to control successfully even highly nonlinear systems. After method description and some discussion, there is performed control simulation and comparison to one chosen conventional control method.
Data bases and discrete event simulation
Boubetra, Abdelhak; Belouadah, Hocine; Mouhoub, Nassreddine
2007-01-01
This paper is an attempt to define how a specific data structure might be used to store, in a persistent manner, temporal information during a computer simulation. In particular, it considers the sort of temporal information generated during a discrete event simulation of a system to which a relational data base exists and considers the demands this data makes on data base design. Facultad de Informática
Discrete time analysis of a repairable machine
Alfa, Attahiru Sule; Castro, I. T.
2002-01-01
We consider, in discrete time, a single machine system that operates for a period of time represented by a general distribution. This machine is subject to failures during operations and the occurrence of these failures depends on how many times the machine has previously failed. Some failures are repairable and the repair times may or may not depend on the number of times the machine was previously repaired. Repair times also have a general distribution. The operating times...
Texture modelling by discrete distribution mixtures
Czech Academy of Sciences Publication Activity Database
Grim, Jiří; Haindl, Michal
2003-01-01
Roč. 41, 3-4 (2003), s. 603-615 ISSN 0167-9473 R&D Projects: GA ČR GA102/00/0030; GA AV ČR KSK1019101 Institutional research plan: CEZ:AV0Z1075907 Keywords : discrete distribution mixtures * EM algorithm * texture modelling Subject RIV: JC - Computer Hardware ; Software Impact factor: 0.711, year: 2003
Discrete Alfven waves in the TORTUS tokamak
International Nuclear Information System (INIS)
Amagishi, Y.; Ballico, M.J.; Cross, R.C.; Donnely, I.J.
1989-01-01
Discrete Alfven Waves (DAWs) have been observed as antenna resistance peaks and as enhanced edge fields in the TORTUS tokamak during Alfven wave heating experiments. A kinetic theory code has been used to calculate the antenna loading and the structure of the DAW fields for a range of plasma current and density profiles. There is fair agreement between the measured and predicted amplitude of the DAW fields in the plasma edge when both are normalized to the same antenna power
Quantifying Discretization Effects on Brain Trauma Simulations
2016-01-01
toward equilibrium from the inflection point (displaced 15.7° from equilibrium). One immediately visible result is that the pressure, stress , and strain...are 10.1° from equilibrium, 0.9° back toward equilibrium from the inflection point (displaced 59.1° from equilibrium), and 44.3° back toward...equilibrium from the inflection point (displaced 15.7° from equilibrium). ...........................................10 Fig. 8 Effect of discretization
Discrete Tolerance Allocation for Product Families
2011-01-01
Abstract This paper extends earlier research on the discrete tolerance allocation problem in order to optimize an entire product family simultaneously. This methodology enables top-down tolerancing approach where requirements on assembly level on products within a family are allocated to single part requirements. The proposed solution has been implemented as an interface with an optimization algorithm coupled with a variation simulation software. The paper also consists of an exten...
A variational synthesis nodal discrete ordinates method
International Nuclear Information System (INIS)
Favorite, J.A.; Stacey, W.M.
1999-01-01
A self-consistent nodal approximation method for computing discrete ordinates neutron flux distributions has been developed from a variational functional for neutron transport theory. The advantage of the new nodal method formulation is that it is self-consistent in its definition of the homogenized nodal parameters, the construction of the global nodal equations, and the reconstruction of the detailed flux distribution. The efficacy of the method is demonstrated by two-dimensional test problems
Bounded solutions and wavefronts for discrete dynamics
Czech Academy of Sciences Publication Activity Database
Malaguti, L.; Řehák, Pavel; Taddei, V.
2004-01-01
Roč. 47, - (2004), s. 1079-1094 ISSN 0898-1221 R&D Projects: GA ČR GA201/01/0079; GA ČR GP201/01/P041 Institutional research plan: CEZ:AV0Z1019905 Keywords : nonlinear difference equation * bounded solution * discrete travelling waves Subject RIV: BA - General Mathematics Impact factor: 0.431, year: 2004
Hyponormal differential operators with discrete spectrum
Directory of Open Access Journals (Sweden)
Zameddin I. Ismailov
2010-01-01
Full Text Available In this work, we first describe all the maximal hyponormal extensions of a minimal operator generated by a linear differential-operator expression of the first-order in the Hilbert space of vector-functions in a finite interval. Next, we investigate the discreteness of the spectrum and the asymptotical behavior of the modules of the eigenvalues for these maximal hyponormal extensions.
Subordinated diffusion and continuous time random walk asymptotics.
Dybiec, Bartłomiej; Gudowska-Nowak, Ewa
2010-12-01
Anomalous transport is usually described either by models of continuous time random walks (CTRWs) or, otherwise, by fractional Fokker-Planck equations (FFPEs). The asymptotic relation between properly scaled CTRW and fractional diffusion process has been worked out via various approaches widely discussed in literature. Here, we focus on a correspondence between CTRWs and time and space fractional diffusion equation stemming from two different methods aimed to accurately approximate anomalous diffusion processes. One of them is the Monte Carlo simulation of uncoupled CTRW with a Lévy α-stable distribution of jumps in space and a one-parameter Mittag-Leffler distribution of waiting times. The other is based on a discretized form of a subordinated Langevin equation in which the physical time defined via the number of subsequent steps of motion is itself a random variable. Both approaches are tested for their numerical performance and verified with known analytical solutions for the Green function of a space-time fractional diffusion equation. The comparison demonstrates a trade off between precision of constructed solutions and computational costs. The method based on the subordinated Langevin equation leads to a higher accuracy of results, while the CTRW framework with a Mittag-Leffler distribution of waiting times provides efficiently an approximate fundamental solution to the FFPE and converges to the probability density function of the subordinated process in a long-time limit. © 2010 American Institute of Physics.
Rivaroxaban with or without Aspirin in Stable Cardiovascular Disease
Eikelboom, John W.; Connolly, Stuart J.; Bosch, Jackie; Dagenais, Gilles R.; Hart, Robert G.; Shestakovska, Olga; Diaz, Rafael; Alings, Marco; Lonn, Eva M.; Anand, Sonia S.; Widimsky, Petr; Hori, Masatsugu; Avezum, Alvaro; Piegas, Leopoldo S.; Branch, Kelley R. H.; Probstfield, Jeffrey; Bhatt, Deepak L.; Zhu, Jun; Liang, Yan; Maggioni, Aldo P.; Lopez-Jaramillo, Patricio; O'Donnell, Martin; Kakkar, Ajay K.; Fox, Keith A. A.; Parkhomenko, Alexander N.; Ertl, Georg; Störk, Stefan; Keltai, Matyas; Ryden, Lars; Pogosova, Nana; Dans, Antonio L.; Lanas, Fernando; Commerford, Patrick J.; Torp-Pedersen, Christian; Guzik, Tomek J.; Verhamme, Peter B.; Vinereanu, Dragos; Kim, Jae-Hyung; Tonkin, Andrew M.; Lewis, Basil S.; Felix, Camilo; Yusoff, Khalid; Steg, P. Gabriel; Metsarinne, Kaj P.; Cook Bruns, Nancy; Misselwitz, Frank; Chen, Edmond; Leong, Darryl; Yusuf, Salim; Aboyans, V.; Ha, J.; Keltai, K.; Lamy, A.; Liu, L.; Moayyedi, P.; Sharma, M.; Stoerk, S.; Varigos, J.; Bhagirath, V.; Bogaty, P.; Botto, F.; Catanese, L.; Donato Magno, J.; Fabbri, G.; Gabizon, I.; Gosselin, G.; Halon, D.; Heldmann, M.; Lamelas, P.; Lauw, M.; Leong, Y.; Liang, D.; Lutay, Y.; Maly, M.; Mikulik, R.; Nayar, S.; Ng, K.; Perera, K.; Pirvu, O.; Ronner, E.; Sato, S.; Smyth, A.; Sokolova, E.; Wiendl, M.; Winkelmann, B.; Yang, X.; Yufereva, Y.; Cairns, J.; Sleight, P.; deMets, D.; Momomura, S. I.; Prins, M. [=Martin H.; Ramsay, T.; Goto, S.; Rouleau, J. L.; Schumi, J.; Thabane, L.; Casanova, A.; Bangdiwala, S.; Deng, E.; Dyal, L.; Khatun, R.; Marsden, T.; Pogue, J.; Tang, C.; Wong, G.; Yuan, F.; Aman, S.; Ariz, A.; Ashton, H.; Belanger, J.; Belanger, M.; Brettell, K.; Chandra, J.; Choppick, C.; Cisternino, D.; Cuncins-Hearn, A.; Di Marino, M.; Diao, L.; Dwomoh, S.; Dykstra, A.; Galatsis, E.; Gasic, T.; Gutierrez, J.; Hamilton, L.; Irwin, L.; Lapensee, C.; Li, A.; Lu, X.; MacRae, L.; Malik, S.; Malvestiti, A.; Mastrangelo, J.; Maystrenko, A.; O'Donnell, L.; Reeh, K.; Szymkow, P.; Thomas, S.; Thrasher, D.; Tyrwhitt, J.; White, L.; Bastone, R.; Berkowitz, S.; Dias, A.; Ho, K.; Keller, L.; Lanius, V.; Lister, K.; Merten, C.; Muehlhofer, E.; Schmidt, K.; Tasto, C.; Tsihlias, E.; Woroniecka-Osio, A.; Orlandini, A.; Niemann, G.; Pascual, A.; Toscanelli, S.; Cabezón, M.; Debaveye, B.; Meeusen, K.; Luys, C.; Broos, K.; Vandenberghe, K.; Luyten, A.; Oliveira, G. B. F.; Vila Nova, D. C.; Konishi, M. Y. N.; Lonn, A.; Turbide, G.; Cayer, M.; Rovito, C.; Standen, D.; Li, J.; Lopez Pico, M.; Dusek, R.; Buzalka, V.; Larsen, J.; Paucar, M. J.; Saarinen, M.; Simon, T.; Bezault, M.; Le Lay, M.; Epstein, L.; Fajardo-Moser, M.; Röser, C.; Putz-Todd, G.; Scheidemantel, F.; Poehler, D.; Renner, J.; Hargitai, A.; Doherty, A. O.; Duffy, N.; Roarty, C.; Nolan, A.; Power, A.; Yuval, R.; Ben Ari, M.; Greenblatt, S.; Marmor, Y.; Lucci, D.; Ceseri, M.; Baldini, E.; Cipressa, L.; Miccoli, M.; Goto, M.; Yamasowa, H.; Kajiwara, M.; Takase, D.; Ikeguchi, K.; Matsumoto, M.; Ishii, M.; Asai, J.; Nozaki, D.; Akatsuka, T.; Yoshida, T.; Shahadan, S.; Md Nasir, N.; Schut, Astrid; Vinck, Leonie; van Leeuwen, Marjelle; Sanchez, J.; Aquino, M. R.; Mararac, T.; Benedyk, K.; Iordache, A.; Ciobanu, A.; Rimbas, R.; Dragoi Galrinho, R.; Magda, S.; Mihaila, S.; Mincu, R.; Suran, B.; Cotoban, A.; Matei, L.; Kursakov, A.; Rusnak, P.; Zakharova, A.; Demidova, E.; Commerford, A.; Lee, S.; Ju, I.; Gunolf, M.; Lorimer, A.; Parkhomenko, L.; Johnson, J.; Anderson, J.; Norby-Slycord., C.; Sala, J.; Sicer, M.; Rasmussen, M.; Luciani, C.; Cartasegna, L.; Beltrano, C.; Medek, G.; Vico, M.; Lanchiotti, P.; Martella, C.; Hominal, M.; Castoldi, M.; Casali, W.; Raimondi, S.; Hasbani, E.; Prado, A.; Paterlini, G.; Waisman, F.; Leonard, M.; Caccavo, A.; Alarcon, V.; Zaidman, C.; Guerlloy, F.; Vogel, D.; Imposti, H.; Dominguez, A.; Hrabar, A.; Fernandez, A.; Schygiel, P.; Sokn, F.; Cuneo, C.; Gutierrez Carrillo, N.; Martinez, G.; Luquez, H.; Costantino, M.; Ruiz, M.; Beccetti, N.; Mackinnon, I.; Cluigt, N.; Ahuad Guerrero, R.; Fanuele, M.; Campisi, V.; Costabel, J.; Romanelli, M.; Bartolacci, I.; Echeverria, M.; Pedrotti, M.; Montaña, O.; Camino, A.; Crespo, C.; Barbieri, M.; Lopez Santi, R.; Tonin, H.; Heffes, R.; Gomez Vilamajo, O.; Vanesio, F.; Allegrini, E.; Garcia Duran, R.; Garcia, C.; Garcia Duran, L.; Schiavi, L.; Mana, M.; Bordonava, A.; Rodriguez, M.; Gutierrez, M.; Garrido, M.; Rodriguez, C.; Ingaramo, A.; Costamagna, O.; Almagro, S.; Gerbaudo, C.; Pelagagge, M.; Bustamante Labarta, M.; Novaretto, L.; Maldini, A.; Lopez, L.; Albisu Di Gennero, J.; Ibanez Saggia, L.; Garcia Vilkas, A.; Alvarez, M.; Stoermann, W.; Vita, N.; Vottero, E.; Macin, S.; Cocco, M.; Onocko, M.; Dran, R.; Gimenez, C.; Cardona, M.; Guzman, L.; Guzman, P.; Martinez, D.; Sarjanovich, R.; Huerta, C.; Scaro, G.; Cuadrado, J.; Rodriguez, G.; Nani, S.; Guardiani, F.; Litvak Bruno, M.; Ceconi, G.; Chacon, C.; Casado, M.; Fernandez Moutin, M.; Maffei, L.; Sassone, S.; Yantorno, M.; Grinfeld, D.; Vensentini, N.; Rolandi, F.; Fallabrino, L.; Majul, C.; Paez, O.; Visser, M.; Luciardi, H.; Mansilla, V.; Gonzalez Colaso, P.; Ferre Pacora, F.; Jure, H.; Parody, M.; Espeche, E.; Whelan, A.; Boyle, A.; Collins, N.; Roberts-Thomson, P.; Rogers, J.; Caroll, P.; Colquhoun, D.; Williams, L.; Shaw, J.; Blombery, P.; Amerena, J.; Lee, C.; Hii, C.; Royse, A.; Royse, C.; Singh, B.; Selvanayagam, J.; Jansen, S.; Thompson, P.; Lo, W.; Hammett, C.; Poulter, R.; Graves, S.; Narasimhan, S.; van den Heuvel, P.; Wollaert, B.; Sinnaeve, P.; Fourneau, I.; Meuris, B.; Vanassche, T.; Ector, B.; Janssens, L.; Debonnaire, P.; Vandekerckhove, Y.; van de Borne, P.; Wautrecht, J.; Motte, S.; Leroy, J.; Schroë, H.; Vrolix, M.; Ferdinande, B.; Vranckx, P.; Benit, E.; Elegeert, I.; Lerut, P.; Wallaert, P.; Hoffer, E.; Borgoens, P.; Dujardin, K.; Brasil, C. K. O. I.; del Monaco, M. I.; Uint, L.; Pavanello, R.; Precoma, D. B.; Vianna, H. S.; Abrantes, J.; Morelli, J.; Manenti, E.; Jaeger, C.; Reis, G.; Giorgeto, F. E.; França, C. C. B.; Quadros, T. F. S.; Saraiva, J.; Costa, M.; de Camargo, O.; Marson Lopes, M.; Silva, J.; Maia, L. N.; Nakazone, M. A.; Mouco, O. M. C. C.; Lemos, M. A. B. T.; Hernandes, M. E.; Pântano, G. S.; de Castro, J. C. M.; Rossi, P. R. F.; Guedes, A. A. M.; Dos Santos, L. B.; dos Santos, F. R.; Vidotti, M. H.; Zimmermann, S. L.; Rech, R.; Nunes, C.; Abib, E.; Oliveira, K. L. C.; Leaes, P. E.; Botelho, R. V.; Navarro, A. L. C.; Silva, R. A.; Arantes, F. B. B.; Dutra, O.; Vaz, R.; Souza, W. K. S. B.; Souza, A. S. B.; Queiroz, W. C. B.; Braile, M.; Ferreira, V.; Izukawa, N. M.; Prakasan, A. K.; Nicolau, J. C.; Dalçóquio, T. F.; Tanajura, L. F. L.; Serrano, C. V.; Hueb, W. A.; Minelli, C.; Borsetti Neto, F. A.; Nasi, L. A.; Martins, S. C. O.; Oliveira, L. F. A.; Silva, M. A. V.; Ferreira, J. O.; de Carvalho Cantarelli, M. J.; Tytus, R.; Pasyk, E.; Pandey, A. S.; Rowe, A.; Cha, J.; Vizel, S.; Babapulle, M.; Semelhago, L.; Saunders, K.; Haligowski, D.; Berlingieri, J.; Nisker, W.; Kiaii, B.; Romsa, J.; Chu, M.; Nagpal, D.; Guo, R.; Mckenzie, N.; Quantz, M.; Bhargava, R.; Bhargava, M.; Mehta, P.; Hill, L.; Heslop, W.; Fell, D.; Hess, A.; Zadra, R.; Zeman, P.; Srivamadevan, M.; Lam, A.; Tai, S.; Al-Qoofi, F.; Spence, F.; Anderson, T.; Kieser, T.; Kidd, W.; Fedak, P.; Smith, E.; Har, B.; Brown, C.; Forgie, R.; Hassan, A.; Pelletier, M.; Searles, G.; Marr, D.; Bessoudo, R.; Douglas, G.; Legare, J.; Petrella, R.; Pavlosky, W.; Ricci, J.; Galiwango, P.; Janmohamed, A.; Kassam, S.; Mukherjee, A.; Vijayaraghavan, R.; Burstein, J.; D'Mello, N.; Glanz, A.; Noiseux, N.; Stevens, L. M.; Basile, F.; Prieto, I.; Normandin, L.; Helou, J.; Do, Q. B.; Bainey, K.; Tymchak, W.; Welsh, R.; Merali, F.; Pandith, V.; Heffernan, M.; Orfi, J.; Mcconachie, D.; Jedrzkiewicz, S.; Della Siega, A.; Robinson, S.; Nadra, I.; Poirier, P.; Dagenais, F.; Voisine, P.; Mohammadi, S.; Doyle, D.; Baillot, R.; Charbonneau, E.; Dumont, E.; Kalavrouziotis, D.; Perron, J.; Jacques, F.; Laflamme, M.; Brulotte, S.; Crete, M.; Degrâce, M.; Delage, F.; Grondin, F.; Lemieux, A.; Michaud, N.; Saulnier, D.; Ross, M. K.; Nguyen, M.; Harvey, R.; Daneault, B.; Hartleib, M.; Guzman, R.; Nguyen, T.; Singal, R.; Bourgeois, R.; Landry, D.; Kamel, S.; Rupka, D.; Kuritzky, R.; Khaykin, Y.; Phaneuf, D. C.; Desjardins, V.; Coll, X.; Huynh, T.; Pilon, C.; Mansour, S.; Lemire, F.; Kokis, A.; Potvin, J.; Campeau, J.; Audet, M.; Boulianne, M.; Dupuis, R.; Lauzon, C.; Pruneau, G.; Senay, B.; Pichette, F.; Cieza, T.; Breton, R.; Belisle, P.; Barabas, M.; Diaz, A.; Costa, R.; Absi, F.; Garand, M.; Rheault, A.; Lemay, C.; Gisbert, A.; Raymond, A.; Barrero, M.; Gagne, C. E.; Rheault, P.; Pepin-Dubois, Y.; Johnston, J.; Mundi, A.; Cohen, G.; Shukle, P.; Baskett, R.; Hirsch, G.; Ali, I.; Stewart, K.; Fenton, J.; Pudupakkam, S.; Willoughby, R.; Czarnecki, W.; Roy, A.; Montigny, M.; Descarries, L.; Mayrand, H.; Comtois, H.; Essiambre, R.; Ringuette, G.; Boutros, G.; Gendreau, R.; Pham, L.; Nguyen, V.; Nguyen-Thanh, H. K.; Ben-Yedder, N.; Nawaz, S.; Fremes, S.; Moussa, F.; Shukla, D.; Labonte., R.; Jano, G.; Bobadilla, B.; Saavedra, J.; Bahamondes, J.; Cobos, J.; Grunberg, E.; Corbalan, R.; Verdejo, H.; Medina, M.; Vega, M.; Nahuelpan, L.; Castañia, F.; Raffo, C.; Vargas, A.; Reyes, T.; Vargas, D.; Perez, L.; Arriagada, G.; Potthoff, S.; Godoy, J.; Stockins, B.; Larenas, G.; Quiñinao, F.; Sepulveda, P.; Trucco, V.; Pincetti, C.; Saavedra, S.; Silva, P.; Vejar, M.; Rodríguez, T.; Rodriguez, J.; Tian, H.; Zhang, J.; Meng, Y.; Wu, X.; Wu, Q.; Wang, Q.; Mu, Y.; Yang, J.; Wang, F.; Zhang, W.; Ke, Y.; Jiang, H.; Yin, P.; Jia, K.; Chen, C.; Wang, Z.; Qi, B.; Yu, L.; Feng, G.; Li, L.; Jiang, L.; Wu, S.; Yu, H.; Wu, Z.; Ding, R.; Liu, S.; Xu, H.; Cao, H.; Bai, X.; Zheng, Y.; Liu, Z.; Sun, H.; Yang, P.; Li, B.; Feng, Z.; Yang, Y.; Xu, Z.; Wu, W.; Meng, Q.; Ge, J.; Dai, Y.; Yang, H.; Chen, X.; Tian, X.; Shi, Y.; Hu, T.; Zhang, R.; Zhao, Q.; Quan, W.; Zhu, Y.; Zheng, Z.; Zhang, S.; Zhao, Y.; Zhao, C.; Wang, R.; Tao, L.; Hu, D.; Wang, Y.; Fan, F.; Huang, W.; Xia, X.; Fu, G.; Jiang, D.; Wang, M.; Li, C.; Xu, K.; Dong, Y.; Chen, Y.; Wu, D.; Wang, C.; Sun, X.; Lu, S.; Zhou, X.; Kong, Y.; Zhang, B.; Sotomayor, A.; Suarez, M.; Ripoll, D.; Herrera, O.; Accini Mendoza, J.; Saad Cure, C.; Reyes, M.; Vidal, T.; Donado Beltran, P.; Hernandez Jaimes, E.; Castillo, H.; Rocha, C.; Forero, L.; Zarate Bernal, D.; Vanstrrahle Gonzalez, L.; Urina Triana, M.; Quintero, A.; Ramirez, N.; Balaguera Mendoza, J.; Aroca Martinez, G.; Cotes, C.; Mercado, A.; Lastra Percy, X.; Perez Mayorga, M.; Rodriguez, N.; Molina de Salazar, D.; Perez Agudelo, J.; Lopez Villegas, L.; Agudelo Ramos, L.; Melo Polo, M.; Esparza Albornoz, A.; Forero Gomez, J.; Sanchez Vallejo, G.; Aristizabal, J.; Gallego, A.; Contreras, C.; Yepez, J.; Angel Escobar, J.; Manzur J, F.; Cohen, L.; Boneu, D.; Garcia Lozada, H.; Barrios, L.; Celemin, C.; Diego, M.; Garcia Ortiz, L.; Montoya, C.; Ramirez, E.; Arcos Palma, E.; Ceron, J.; Acosta, G.; Gomez Mesa, J.; Velasquez, J.; Barreto, D.; Trujillo Dada, F.; Trujillo Accini, F.; Cano, R.; Corredor de La Cruz, K.; Maria, V.; Palmera, J.; Vesga, B.; Hernandez, H.; Moreno Silgado, G.; Aruachan Vesga, S.; Burgos Martinez, E.; Quintero Villareal, G.; Solano Ayazo, F.; Porto Valiente, J.; Zidkova, E.; Krupicka, P.; Bultas, J.; Mandysova, E.; Lubanda, J.; Horak, J.; Belohlavek, J.; Kovarnik, T.; Gorican, K.; Rucka, D.; Smid, O.; Dostalova, G.; Skalicka, H.; Karetova, D.; Pavlinak, V.; Kuchynkova, S.; Marek, J.; Rob, D.; Ravlykova, K.; Prochazka, P.; Siranec, M.; Urbanec, T.; Vareka, T.; Nesvadbova, P.; Kaletova, M.; Indrakova, J.; Kryza, R.; Heczko, M.; Hanak, P.; Jancar, R.; Kocurkova, L.; Marcinek, G.; Cermak, O.; Drasnar, T.; Richter, M.; Kaspar, J.; Spinar, J.; Parenica, J.; Parenicova, I.; Schildberger, J.; Toman, O.; Ludka, O.; Poloczek, M.; Musil, V.; Miklik, R.; Labrova, R.; Lokaj, P.; Felsoci, M.; Bocek, O.; Kanovsky, J.; Zatocil, T.; Jerabek, P.; Matuska, J.; Jankovic, M.; Jankovicova, H.; Tesak, M.; Sulc, D.; Svacinova, H.; Radvan, M.; Bednar, J.; Motovska, Z.; Petr, R.; Fischerova, M.; Branny, M.; Vodzinska, A.; Cerny, J.; Indrak, J.; Sknouril, L.; Maly, J.; Vacek, T.; Prazak, O.; Broulikova, K.; Hajsl, M.; Jarkovsky, P.; Kamenik, L.; Kotik, I.; Krcova, E.; Sedlon, P.; Skvaril, J.; Cernohous, M.; Kohoutek, J.; Levcik, M.; Holek, M.; Hajdusek, P.; Foltynova Caisova, L.; Novak, V.; Kladivkova, M.; Slaby, J.; Houra, M.; Vojtisek, P.; Novotny, V.; Lazarak, T.; Pliva, M.; Pirk, J.; Barciakova, L.; Jandova, R.; Adamkova, V.; Galovcova, M.; Peterkova, L.; Turek, D.; Prochazka, J.; Belohoubek, J.; Spinarova, L.; Panovsky, R.; Novotny, P.; Krejci, J.; Hude, P.; Ozabalova, E.; Godava, J.; Honek, T.; Kincl, V.; Benesova, M.; Buckova, J.; Canadyova, J.; Mokracek, A.; Homza, M.; Stverka, P.; Florian, J.; Lukac, B.; Polasek, R.; Kucera, P.; Seiner, J.; Karasek, J.; Coufal, Z.; Stastny, J.; Cernicek, V.; Skalnikova, V.; Jiresova, E.; Brat, R.; Sieja, J.; Gloger, J.; Berger, P.; Prochazkova, I.; Samlik, J.; Brtko, M.; Tuna, M.; Polansky, P.; Omran, N.; Myjavec, A.; Hrdinova, M.; Jansky, P.; Kratochvilova, R.; Burkert, J.; Koubek, F.; Fiala, R.; Paulasova Schwabova, J.; Lindner, J.; Hlubocky, J.; Spacek, M.; Marcian, P.; Hanak, V.; Pozdisek, Z.; Lonsky, V.; Santavy, P.; Troubil, M.; Straka, Z.; Budera, P.; Fojt, R.; Talavera, D.; Tretina, M.; Nemec, P.; Orban, M.; Bedanova, H.; Wiggers, H.; Tougaard, R.; Larsen, A.; Nielsen, H.; Mattsson, N.; Gunnar, G.; Bruun, N.; Folke, F.; Soendergaard, K.; Koeber, L.; Frydland, M.; Fuchs, A.; Bang, L.; Houlind, K.; Olsen, M.; Soerensen, V.; Overgaard Andersen, U.; Dixen, U.; Refsgaard, J.; Moeller, D.; Zeuthen, E.; Lund, J.; Soegaard, P.; Jensen, S.; Duarte, Y.; Duarte, W.; Cáceres, S.; Pow Chon Long, F.; Peñaherrera, C.; Anzules, N.; Sánchez, M.; Zuleta, I.; López, J.; Villota, M.; Sánchez, H.; Perugachi, C.; Gómez, S.; Morejón, P.; Mármol, R.; Guamán, S.; Trujillo, F.; Escobar, M.; Carrera, F.; Ponce, F.; Terán, P.; Carrasco, S.; Tuomilehto, J.; Humaloja, K.; Lindberg, L.; Tuomilehto, H.; Tuominen, M.-L.; Kantola, I.; Juliard, J.; Feldman, L.; Ducrocq, G.; Boulogne, C.; Petitalot, V.; Leclercq, F.; Roubille, F.; Agullo, A.; Ferrari, E.; Chiche, O.; Moceri, P.; Boccara, F.; Charbonnier, M.; Azeddine, B.; Ederhy, S.; Soulat Dufour, L.; Cohen, A.; Etienney, A.; Messas, E.; Calvalido, A.; Galloula, A.; Zarka, S.; Courtois, M.-C.; Mismetti, P.; Accassat, S.; Buchmuller, A.; Moulin, N.; Bertoletti, L.; Seffert, B.; Sevestre, M.; Samy Modeliar Remond, S.; Dupas, S.; Mardyla, J.; Le Gloan, S.; Cayla, G.; Cornillet, L.; Schmutz, L.; Motreff, P.; Souteyrand, G.; Amonchot, A.; Barber-Charmoux, N.; Combaret, N.; Malcles, G.; Brenner, S.; Christa, M.; Duengen, H.; Krackhardt, F.; Bobenko, A.; Hashemi, D.; Stellbrink, C.; Stellbrink, E.; Köster, C.; Guerocak, O.; Bourhaial, H.; Oumbe Tiam, S.; Kemala, E.; Froemke, J.; Kadel, C.; Moellinger, H.; Friedrich, K.; Rafoud, K.; Braun-Dullaeus, R.; Herold, J.; Ganzer, M.; Jeserich, M.; Kimmel, S.; Haggenmiller, S.; Schoengart, H.; Voehringer, H.; Opitz, C.; Appel, K.; Appel, S.; Utech, A.; Finger, C.; Duersch, M.; Dorsel, T.; Wistorf, N.; Grude, M.; Nikol, S.; Ueberschaer, D.; Kast, P.; Darius, H.; Sommer, S.; Girke, F.; Oeztuerk, C.; Ranft, J.; Mikalo, A.; Schellong, S.; Voigts, B.; Mueller, C.; Jungmair, W.; Davierwala, P.; Misfeld, M.; Bomke, K.; Akhavuz, O.; Haensig, M.; Vorpahl, M.; Blem, A.; Langer, G.; Nover, I.; Koehler, T.; Bajnok, L.; Marton, Z.; Laszlo, Z.; Noori, E.; Veress, G.; Fogarassy, G.; Aradi, D.; Kelemen, B.; Vertes, A.; Davidovits, Z.; Zsary, A.; Kis, E.; Hepp, T.; Koranyi, L.; Peterfai, E.; Bezzegh, K.; Bakai, J.; Agardi, I.; Boda, Z.; Razso, K.; Poor, F.; Varallyay, Z.; Jarai, Z.; Sallai, L.; Dudas, M.; Barton, J.; Mahmood, K.; Makki, H.; McAdam, B.; Salim, T.; Murphy, A.; Crean, P.; Liddy, A. M.; Mahon, N.; Khan, I.; Hassan, S.; Curtin, R.; McFadden, E.; MacNeill, B.; Kyvelou, S.; Canavan, M.; Veerasingam, D.; Dinneen, S.; Halabi, M.; Rosenfeld, I.; Levinas, T.; Goldberg, A.; Khateeb, A.; Zimlichman, R.; Ben-Aharon, J.; Beniashvili, A.; Betsalel, A.; Zeltser, D.; Rogowski, O.; Mardi, T.; Rozenbaum, Z.; Turgeman, Y.; Or, T.; Rabkin, Y.; Klainman, E.; Halabi, S.; Halon, D. A.; Katz, A.; Plaev, T.; Drogenikov, T.; Atar, S.; Kilimnik, M.; Wishniak, A.; Merei, M.; Zvi, Y.; Nikolsky, E.; Zukermann, R.; Petcherski, S.; Bosi, S.; Gaitani, S.; Naldi, M.; Barbieri, A.; Faggiano, P.; Guidetti, F.; Adamo, M.; D’Aloia, A.; Magatelli, M.; Robba, D.; Mos, L.; Vriz, O.; Sinagra, G.; Maras, P.; Doimo, S.; Cosmi, F.; D'Orazio, S.; Oltrona Visconti, L.; Leonardi, S.; Vullo, E.; Sbaffi, A.; Azzara, G.; Mauri, S.; Gianni, U.; de Matteis, C.; Campidonico, U.; Di Pasquale, G.; Di Niro, M.; Riva, L.; Filippini, E.; Di Biase, M.; Ieva, R.; Martone, A.; Mandorla, S.; Regni, O.; Capponi, E. 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Yuba, K.; Miyajima, H.; Tobetto, Y.; Yoneda, K.; Ogura, R.; Kobayashi, H.; Takamura, T.; Enkou, K.; Ochi, Y.; Yamada, D.; Kuramochi, T.; Misumi, K.; Iiduka, D.; Hirose, M.; Tone, K.; Taniguchi, Y.; Ebihara, T.; Makino, M.; Yokota, M.; Nitta, M.; Udo, A.; Shimizu, S.; Fujii, K.; Iwakura, K.; Okamura, A.; Inoue, K.; Nagai, H.; Hirao, Y.; Tanaka, K.; Tanaka, N.; Yamasaki, T.; Oka, T.; Iwamoto, M.; Tanaka, T.; Nakamaru, R.; Okada, M.; Takayasu, K.; Sumiyoshi, A.; Inoue, H.; Kitagaki, R.; Ninomiya, Y.; Mizutomi, K.; Koizumi, I.; Funada, A.; Tagawa, S.; Kamide, S.; Saku, K.; Ideishi, M.; Ogawa, M.; Uehara, Y.; Iwata, A.; Nishikawa, H.; Ike, A.; Sugihara, M.; Imaizumi, S.; Fujimi, K.; Kawamura, A.; Sako, H.; Morito, N.; Morii, J.; Fukuda, Y.; Yahiro, E.; Matsunaga, A.; Matsumoto, N.; Noda, K.; Shiga, Y.; Nagata, Y.; Kimura, K.; Ebina, T.; Hibi, K.; Iwahashi, N.; Maejima, N.; Konishi, M.; Matsushita, K.; Minamimoto, Y.; Kawashima, C.; Nakahashi, H.; Kimura, Y.; Takahashi, H.; Matsuzawa, Y.; Kirigaya, J.; Sato, R.; Kikuchi, S.; Ogino, Y.; Kirigaya, H.; Kashiwase, K.; Hirata, A.; Takeda, Y.; Amiya, R.; Higuchi, Y.; Sakaguchi, T.; Nakano, T.; Matsusaki, N.; Suzuki, S.; Hayashi, T.; Nakatani, S.; Koide, M.; Kobayashi, T.; Hamanaka, Y.; Makino, N.; Sotomi, Y.; Abe, M.; Fujieda, H.; Hashimoto, K.; Teratani, Y.; Abe, Y.; Yokoyama, Y.; Higashino, H.; Okuda, H.; Yamazato, M.; Noda, T.; Arai, M.; Ono, K.; Hirose, T.; Iwama, M.; Warita, S.; Goto, Y.; Abe, S.; Kojima, T.; Yoshizane, T.; Tanihata, S.; Fujii, T.; Yagasaki, H.; Miwa, H.; Ishiguro, M.; Kato, T.; Watanabe, R.; Horio, S.; Mita, T.; Hirayama, A.; Watanabe, I.; Hiro, T.; Nakai, T.; Takayama, T.; Yoda, S.; Yajima, Y.; Okubo, K.; Okumura, Y.; Kato, M.; Fukamachi, D.; Aizawa, Y.; Sonoda, K.; Iida, K.; Sasaki, N.; Iso, K.; Takahashi, K.; Kougo, T.; Haruta, H.; Kurokawa, S.; Mano, H.; Nagashima, K.; Onaka, H.; Doi, H.; Hirano, N.; Okamoto, F.; Mori, K.; Ri, G.; Zushi, R.; Otsuka, K.; Inoko, M.; Haruna, T.; Nakane, E.; Miyamoto, S.; Izumi, T.; Honjo, S.; Ikeda, H.; Wada, Y.; Funasako, M.; Hayashi, H.; Hamasaki, A.; Sasaki, K.; Seko, Y.; Nakasone, K.; Hanyu, M.; Iwasaki, Y.; Iwasaki, K.; Ayano, S.; Hirokami, M.; Omoto, Y.; Sasaki, H.; Sato, H.; Yuda, S.; Okubo, M.; Matsuo, H.; Tsuchiya, K.; Kawase, Y.; Miyake, T.; Kondo, H.; Hattori, A.; Kikuchi, J.; Okamoto, S.; Hirata, T.; Kawamura, I.; Ota, H.; Omori, H.; Tanigaki, T.; Kamiya, H.; Sobue, Y.; Komoda, T.; Akatsuka, Y.; Yamamoto, M.; Isegawa, K.; Takanezawa, M.; Kataoka, C.; Imamaki, M.; Shibata, Y.; Yasuda, K.; Shimano, M.; Ozaki, R.; Morishita, Y.; Okabe, K.; Kondo, K.; Miura, A.; Manita, M.; Tabata, K.; Asahi, T.; Mashidori, T.; Higa, N.; Nakata, M.; Himi, T.; Matsudo, Y.; Sekine, T.; Hou, K.; Tonoike, N.; Hama, Y.; Tanaka, S.; Ge, B.; Takahara, M.; Ishimura, M.; Shikada, T.; Ueno, H.; Amemiya, H.; Hisamatsu, Y.; Sada, K.; Sato, T.; Harada, K.; Nakamura, T.; Ako, J.; Tojo, T.; Shimohama, T.; Kishihara, J.; Ishii, S.; Fukaya, H.; Meguro, K.; Nishino, Y.; Inoue, M.; Matsui, Y.; Omura, Y.; Kawakami, H.; Matsuoka, H.; Oshita, A.; Seike, F.; Kondo, N.; Miyoshi, T.; Yamada, Y.; Uchiya, T.; Kikuchi, Y.; Koretsune, Y.; Abe, H.; Shinouchi, K.; Nishida, H.; Yasumura, K.; Date, M.; Ueda, Y.; Iida, Y.; Idemoto, A.; Toriyama, C.; Yokoi, K.; Mishima, T.; Yamada, T.; Fukunami, M.; Morita, T.; Furukawa, Y.; Kawasaki, M.; Kikuchi, A.; Tamaki, S.; Seo, M.; Shirakawa, Y.; Ikeda, I.; Fukuhara, E.; Kawai, T.; Kayama, K.; Kawahira, M.; Tanabe, K.; Nakamura, J.; Shimomura, H.; Kudo, T.; Morisaki, S.; Ogura, Y.; Chazono, N.; Onoue, Y.; Matsumuro, Y.; Shirakawa, T.; Nishi, M.; Kinoshita, N.; Nakamura, R.; Miyai, N.; Ohta, K.; Sawanishi, T.; Takahashi, A.; Hada, T.; Nakajima, S.; Taniguchi, N.; Mizuguchi, Y.; Takahashi, Y.; Hashimoto, S.; Machida, M.; Hirabayashi, K.; Morimoto, S.; Higashino, Y.; Otsuji, S.; Takiuchi, S.; Yabuki, M.; Hasegawa, K.; Shishikura, D.; Ibuki, M.; Ishibuchi, K.; Nagayama, S.; Ishii, R.; Tamaru, H.; Yamamoto, W.; Utsu, N.; Miyakoshi, K.; Nakashima, D.; Tsukuda, K.; Ueda, K.; Nakano, A.; Fukuda, T.; Ikeda, S.; Tsuchiya, H.; Toshima, S.; Tateno, R.; Ishikubo, T.; Suguta, M.; Nakamura, S.; Funatsu, A.; Mizobuchi, M.; Tanaka, M.; Nagai, T.; Hirano, S.; Hashimoto, T.; Doi, T.; Shirasaka, A.; Takeda, S.; Sasaki, Y.; Ohya, H.; Hosokawa, A.; Nishina, N.; Koki, B.; Ando, K.; Hiramori, S.; Soga, Y.; Tomoi, Y.; Tohoku, S.; Shirai, S.; Hyodo, M.; Isotani, A.; Domei, T.; Kuramitsu, S.; Morinaga, T.; Hayashi, M.; Hiromasa, T.; Nagae, A.; Yamaji, Y.; Nakao, K.; Sakamoto, T.; Taguchi, E.; Tsurugi, T.; Tanaka, Y.; Suzuyama, H.; Koyama, J.; Nagano, M.; Okamatsu, H.; Kodama, K.; Nakamura, M.; Horibata, Y.; Sone, M.; Tsunemori, M.; Bando, M.; Nakayama, T.; Tanigaito, Y.; Nomoto, M.; Sawamura, T.; Unoki, T.; Lim, C. W.; Zainal Rashid, R.; Najme Khir, R.; Ibrahim, K. S.; Wan Azman, W. A.; Sridhar, G. S.; Watson, T.; Abu Kassim, Z.; Mahmood Zuhdi, A. S.; Abdul Hafidz, M. I.; Abu Hassan, M. R.; Wan Rahimi Shah, W. F.; Karthikesan, D.; Mohd Suan, M. A.; Md Ali, S. M.; Kasim, S.; Mohd Arshad, M. K.; Ismail, J. R.; Ibrahim, Z. O.; Chua, N. Y. L.; Abdul Rahim, A. A.; Rusani, B. I.; Yap, L. B.; Zamrin, D. M.; Amir, M. A.; Ismail, N. I.; Mohammad Razi, A. A.; Prins, F.; Bendermacher, P.; Burg, M.; Lok, D.; van der Sluis, A.; Martens, F.; Badings, E.; Milhous, J.; van Rossum, P.; Viergever, E.; van Hessen, M.; Willems, F.; Tjon Joe Gin, R.; Swart, H.; Oomen, A.; Kromhout, S.; Lauwerijssen, I.; Daalmans, M.; Breedveld, R.; de Vries, K.; Feenema Aardema, M.; Hofma, S.; van der Borgh, R.; van Nes, E.; Göbel, E.; Oei, F.; Dorman, H.; Bos, R.; Zoet-Nugteren, S.; Emans, M.; Kragten, H.; Lenderink, T.; Feld, R.; Herrman, J.; van Bergen, P.; Gosselink, M.; Elvan, A.; Hoekstra, E.; The, S.; de Vries, R.; Zegers, E.; Oude Ophuis, T.; Remmen, J.; Bech, J.; Kooistra, J.; den Hartog, F.; Oosterhof, T.; Bartels, G.; Posma, J.; Nierop, P.; Liem, A.; van der Zwaan, C.; Asselman, M.; van Eck, J.; Gevers, R.; van Gorselen, E.; van Hal, J.; Terpstra, W.; Groenemeijer, B.; Jerzewski, A.; Hoogslag, P.; Geertman, J.; de Groot, M.; Dijkstra, B.; Loyola, A.; Sulit, D.; Mercado, M. J.; Rey, N.; Evangelista, L.; Abola, M.; Padua, L.; Morales, D.; Palomares, E.; Abat, M.; Santos, R.; Rogelio, G.; Chua, P.; Baello, R.; del Pilar, J.; Alianza, M.; Alcaraz, J.; Alcaraz, L.; Ebo, G.; Guido-Saliot, I.; Tirador, L.; Estoce, E.; Ygpuara, M.; Cruz, J.; Anonuevo, J.; Pitargue, A.; Janion, M.; Drewniak, Z.; Guzik, B.; Nowak, M.; Nosal, M.; Niewiara, Ł; Gajos, G.; Bury, K.; Czubek, U.; Misztal, M.; Grzybczak, R.; Zalewski, J.; Kruszelnicka-Kwiatkowska, O.; Żabówka, M.; Rynkiewicz, A.; Grzybowski, A.; Szałkowski, P.; Broncel, M.; Gorzelak, P.; Możdżan, M.; Olszewska Banaszczyk, M.; Szuba, A.; Tabin, M.; Chachaj, A.; Czarnecka, D.; Terlecki, M.; Klocek, M.; Maga, P.; Coman, I.; Tarlea, M.; Ghionea, M.; Gavrila, C.; Dimulescu, D.; Popescu, A.; Stoicescu, C.; Vintila, V.; Florescu, M.; Baghilovici Cretu, D.; Suran, M.; Mihalcea, D.; Lungeanu Juravle, L.; Cinteza, M.; Calin, I.; Bicescu, G.; Vasile Toma, N.; Udroiu, C.; Gherghinescu, C.; Darabont, R.; Patrascu, N.; Constantinescu, C.; Popescu, I.; Sinescu, C.; Andrei, C.; Axente, L.; Arsenescu, C.; Statescu, C.; Ardeleanu, I.; Anghel, L.; Benedek, I.; Benedek, T.; Kinga, P.; Banga, D. K.; Bobescu, E.; Doka, B.; Dobreanu, D.; Sirbu, V.; Rudzik, R.; Kantor, K.; Sus, I.; Gaita, D.; Maximov, D.; Brie, D.; Mosteoru, S.; Olariu, I.; Iancu, A.; Marc, M.; Hagiu, R.; Manole, V.; Molnar, A.; Dregoesc, I.; Iliesiu, A.; Armean, P.; Parvu, I.; Deleanu, A.; Lighezan, D.; Buzas, R.; Petrescu, L.; Nicola, R.; Dan, R.; Crisan, S.; Trasca, L.; Teodorescu, I.; Zara, O.; Tiron, T.; Tesloianu, D.; Spiridon, M.; Vintila, M.; Baluta, M.; Chioncel, O.; Stoica, E.; Kulcsar, I.; Antohi, L.; Strazhesko, I.; Tkacheva, O.; Sharashkina, N.; Pykhtina, V.; Vasyuk, Y.; Shkolnik, E.; Khadzegova, A.; Sadulaeva, I.; Ivanova, S.; Nesterova, E.; Nesvetov, V.; Shupenina, E.; Shcherbak, M.; Sizova, Z.; Beloborodova, A.; Pozdnyakov, Y.; Tarasov, A.; Shvedov, I.; Zabashta, S.; Ryzhikova, I.; Barbarash, O.; Pecherina, T.; Vatutin, M.; Inozemceva, A.; Kazachek, Y.; Mineeva, E.; Kupriyanova, T.; Voevoda, M.; Gafarov, V.; Gromova, E.; Panov, D.; Voevoda, E.; Kovalkova, N.; Ragino, Y.; Poponina, T.; Poponina, Y.; Garganeeva, N.; Repin, A.; Vershinina, E.; Borodina, E.; Kalashnikova, T.; Safyanova, O.; Osipova, I.; Antropova, O.; Pyrikova, N.; Polyakova, I.; Efremushkina, A.; Guryanova, N.; Kiseleva, E.; Lomteva, E.; Shtyrova, T.; Novikova, N.; Parfenov, D.; Volovchenko, A.; Averkov, O.; Pavlikova, E.; Vaulina, L.; Pletnikova, I.; Mishchenko, L.; Saranin, S.; Tsupko, I.; Kuznetsova, N.; Zateyshchikov, D.; Dankovtseva, E.; Vlazneva, Y.; Tolokonnikova, N.; Zhurina, M.; Zubova, E.; Aseycheva, O.; Sigalovich, E.; Vertkin, A.; Rodiukova, I.; Komissarov, S.; Sokolova, R.; Ausheva, A.; Salbieva, A.; Yusubova, A.; Isakova, S.; Hranai, M.; Obona, P.; Cisar, P.; Semetko, J.; Vanova, P.; Ferencikova, Z.; Vykoukalova, T.; Gaspar, L.; Caprnda, M.; Bendzala, M.; Pella, D.; Fedacko, J.; Hatalova, K.; Drozdakova, E.; Peter, O.; Ntsekhe, M.; de Andrade, M.; Seedat, S.; Gani, M.; van Zyl, L.; Naude, M.; Cronje, T.; van Zyl, F.; Engelbrecht, J.; Jansen, J.; Roos, J.; Makotoko, E.; Pretorius, C.; Mirna, S.; Nell, H.; Pretorius, M.; Basson, M.; Njovane, X.; Mohamed, Z.; Pillay, T.; Dawood, S.; Horak, A.; Lloyd, E.; Hitzeroth, J.; Mabin, T.; Abelson, M.; Klug, E.; Gebka, M.; Hellig, F.; Alison, M.; Bae, J.; Kim, C.; Kim, D.; Joo, S.; Park, C.; Kim, Y.; Jarnert, C.; Rydén, L.; Mooe, T.; Binsell-Gerdin, E.; Dellborg, M.; Torstensson, I.; Albertsson, P.; Hiller, M.; Perers, E.; Johansson, L.; Jansson, J. H.; Al-Khalili, F.; Almroth, H.; Andersson, T.; Eriksson Östman, M.; Pantev, E.; Utter, F.; Tengmark, B. O.; Olsson, Å; Liu, B.; Rasmanis, G.; Wahlgren, C. M.; Thott, O.; Moccetti, T.; Rossi, M. 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M.; Tremblay, H.; Bergeron, A.; Dumont, J.; Keilani, S.; Landry, P.; Deneufbourg, I.; Breton, C.; Bilodeau, N.; Côté, M.; Dumont, F.; Dufort, L.; Marcoux, D.; David, M.; Otis, R.; Parks, J.; Cepidoza, C.; Janz, W.; Weighell, W.; Yaworski, S.; Boyd, K.; Lambert, J.; Shea-Landry, G.; Reid, K.; Thiessen, S.; Nemtean, D.; Futers, S.; Drouin, K.; Masson, C.; Arseneault, M. C.; Lachance, N.; Bergeron, C.; Boudreault, C.; Perkins, L.; Barnett, A.; Fortin, J.; Duclos, R.; Vallières, C.; Bouchard-Pilote, C.; Ouimet, F.; Roberge, B.; Couture, M. L.; Deshaies, D.; Bastien, A.; Chartrand, M. J.; Gagné, N. L.; Desbiens, K.; Alarie, P.; Cassan, J.; Ducharme, Y.; Roy D Tapps, I.; Bolduc, H.; Laliberté, J.; Hickey, L.; Spero, M.; Bernstein, M.; Clement, J.; Pawluch, A.; Ricci-Bonzey, M.; Richer, J.; Vaillancourt, J.; Ward, B.; Mostafai Rad, P.; Oleski, L.; Karkhanis, R.; Hartleib, V.; Poirier, R.; Hidalgo, J.; Hernandez, C.; Obreque, C.; Quilapi, D.; Villa, F.; Iturriaga, C.; Ferrada, M.; Navarrete, S.; Becerra, E.; Vargas, C.; Roque, C.; Alarcon, J.; Diaz, D.; Sepulveda, M.; Villan, C.; Garcia, N.; Lara, C.; Lezana, B.; Basso, N.; Torres, G.; Pasmino, C.; Gonzalez, S.; Medina, D.; Rodriguez, T.; Guo, T.; Chen, S.; Han, W.; Shi, D.; Zhang, Q.; Li, W.; Cui, L.; Huang, Z.; Gong, X.; Liu, D.; Tan, S.; Caicedo, L.; Rodriguez, A.; Mejia, I.; Escalante Ruiz, J.; Camera Ochoa, C.; Conrrado Ortega, Y.; Accini Diaz, A.; Rodriguez, B.; Lopez-Lopez, J.; Di Stefano, K.; Florez, L.; Manco, T.; Rodriguez, D.; Urina, A.; de La Hoz, L.; Almendrales, L.; Bello, O.; Urrea Valencia, H.; Correa Rivera, P.; Perdomo, I.; Alzate, J.; Rivera, E.; Jimenez, N. 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L.; Savoldi, D.; Fiorini, M.; Ramani, F.; Mariottoni, B.; Rizzotti, D.; Di Matteo, C.; Musio, S.; Pieroni Minciaroli, S.; Serani, S.; Aloisi, A.; Attanasio, C.; Tricoli, M.; Giordano, V.; Andrioli, V.; Biundo, V.; Tullio, L.; Schiff, D.; Trovarelli, P.; Chiodi, R.; Sampaolesi, S.; Cina, M. T.; Abatello, M.; de Tora, M.; Pietrucci, F.; Pezzetta, S.; Chiminelli, E.; Dall’Asta, A.; Bennati, M.; Elia, A.; Bizzoco, M.; Iaquaniello, A.; Spigarelli, R.; Cremonesi, C.; Gagliardi, M.; Torricelli, L.; Ijichi, N.; Shiraiwa, K.; Murakami, M.; Takeshita, K.; Sato, M.; Shiratori, A.; Kinjo, K.; Tomita, K.; Mizuno, M.; Kurihara, F.; Tachibana, M.; Nitta, Y.; Unno, K.; Hiramatsu, H.; Sano, A.; Nanatsumura, M.; Tanikawa, I.; Uesugi, K.; Banno, S.; Miyata, T.; Kujuji, A.; Kawai, K.; Maegawa, A.; Koseki, T.; Watanabe, Y.; Aoki, S.; Maesawa, M.; Suzuki, A.; Itose, Y.; Konishi, K.; Fujieda, K.; Nakade, S.; Minami, M.; Yoneda, J.; Akiyama, R.; Sakai, S.; Nakatani, K.; Yamazaki, A.; Funama, M.; Kaneko, E.; Morii, S.; Onishi, M.; Sone, A.; Sagawa, N.; Iwai, F.; Kawahara, A.; Hasimoto, C.; Ueki, M.; Kamiji, M.; Ando, M.; Yokoo, M.; Okada, Y.; Yamada, H.; Matsushige, N.; Nagato, A.; Matsumoto, R.; Nishikawa, M.; Oka, I.; Kitou, S.; Tachiuchi, M.; Nakagawa, M.; Yoneda, S.; Iwasa, K.; Matsuda, J.; Oda, A.; Tokudome, S.; Kaneyuki, Y.; Higaki, M.; Yoneda, H.; Kajita, C.; Suwa, K.; Sato, E.; Nagata, T.; Kubo, Y.; Umesu, A.; Ohashi, K.; Takeuchi, M.; Tanaka, I.; Nobehara, T.; Yamano, R.; Yumiba, A.; Hamada, M.; Nishihata, T.; Ohashi, Y.; Morita, M.; Endo, M.; Matsugi, M.; Tateishi, H.; Nakamori, R.; Yamashita, Y.; Okabe, M.; Matsuo, M.; Ono, T.; Shigeyama, Y.; Ichiyanagi, M.; Sugimori, K.; Ohmura, C.; Igarashi, M.; Aotsuka, S.; Komoda, N.; Watanabe, M.; Enomoto, Y.; Suzuki, Y.; Kawaguchi, A.; Kasahara, A.; Koide, A.; Sakatani, T.; Kurihara, T.; Yokota, S.; Futagi, R.; Amemiya, Y.; Ono, E.; Maeda, A.; Kadono, K.; Ishiguchi, Y.; Kikuchi, R.; Kuramatsu, M.; Nakamura, E.; Chiba, S.; Higa, A.; Kitahashi, M.; Tanaka, H.; Ito, T.; Oba, M.; Tsubouchi, M.; Toshima, M.; Morishita, M.; Miyano, A.; Kondo, M.; Watanabe, K.; Shibata, R.; Tosaki, Y.; Ito, Y.; Saoda, M.; Yamasaki, E.; Kadosaki, S.; Motooka, S.; Akiyoshi, H.; Morio, S.; Nemoto, H.; Yoshizawa, S.; Okabe, N.; Semba, K.; Yoshida, A.; Lee, Y.; Yoshida, M.; Iwashita, Y.; Takeda, A.; Maezato, M.; Kawahira, K.; Yoshikawa, M.; Okamoto, N.; Nishimura, M.; Matsuura, K.; Fukunaga, M.; Fukai, K.; Osakabe, Y.; Yamamura, K.; Koike, M.; Shibuya, S.; Shiramata, M.; Ono, Y.; Tsujimoto, Y.; Tadokoro, T.; Morishita, N.; Matsuo, Y.; Yumoto, I.; Sakazaki, S.; Atarashi, A.; Nabata, Y.; Okuda, N.; Fujita, A.; Matsuo, A.; Ishizawa, Y.; Shibata, H.; Ootsuka, M.; Taimatsu, R.; Takeuchi, A.; Sumi, Y.; Yamamoto, F.; Araki, Y.; Tanaka, A.; Kuroda, S.; Sakata, R.; Okada, N.; Sawada, Y.; Miyata, M.; Asayama, H.; Koga, N.; Miki, T.; Yamaguchi, N.; Hashimoto, A.; Fukuike, C.; Kubo, A.; Yamasaki, M.; Mori, Y.; Nakayama, S.; Kobayashi, Y.; Takenaka, S.; Mashima, M.; Katsuta, H.; Matsumura, T.; Yanagida, S.; Watanabe, N.; Kodama, S.; Kusano, M.; Yamamoto, N.; Kamada, R.; Suzuki, K.; Itami, K.; Hasebe, Y.; Fujita, N.; Kubota, S.; Usuki, A.; Okamoto, M.; Uno, S.; Chikuma, A.; Kishikawa, H.; Yano K Nakano, C.; Otaguro, M.; Kayashima, Y.; Shinoda, M.; Jaafar, S. M.; Baharuddin, S.; Gembor, J.; Ahmad, H.; Syed Mansor, S. M.; Abdullah, W. M.; Shafie, Z.; Muhamad Yunus, S.; Alwi, S. M.; Hussin, N.; Basri, N. A.; Ling Ling, L.; Naem, N. S.; Rutten, R.; Rademaker, H.; van Buijsen, M.; Scholten, M.; Stuij, S.; van Zeijst, M.; van Houwelingen, K.; Engelen, W.; Kramer, H.; Maassen, E.; Verhoeven, P.; Awater, J.; Terwisscha van Scheltinga, C.; Meijlis, P.; Blom, L.; Bos, M.; van der Wal, M.; van Laerhoven, G.; Jacobs, T.; Tan-Urgert, B.; van de Gaag, J.; den Boer, P.; Verlek, E.; Lardinois, R.; Coenjaerds, C.; Hendrick, R.; Schoep, J.; Froma, E.; van Nes, C.; Beuving, D.; Krikken, J.; Drent, I.; Geerlings, F.; Buvelot, S.; Wissenburg, A.; Dijkshoorn, A.; van Setten van der Meer, L.; Singerling, M.; van Wijk, D.; Bor, A.; Aukema-Wouda, Z.; Hendriks-van Woerden, M.; Kort, I.; Danse, I.; van der Knaap, M.; de Jong, C.; Temminck, M.; Schaefer, T.; van der Ven, N.; Drost, I.; Mulder, R.; de Vos, A.; de Hoop, M.; Post, G.; Wielandt, D.; Edorot, N.; de Castro, K.; Flotildes, M.; Mulingtapang, T.; Vasquez, S.; Facundo, S.; Peralta, M.; Jose, M.; Bandiez, J.; Sulit, P.; Joaquin, F.; Arbis, M. G.; Silva, C.; Delgado, D.; de Leon, R.; Maglasang, P.; Sian, A.; Alagban, C.; Alcorano, J.; Marcelo, M. J.; Dela Pena, C.; Hyra, I.; Malkiewicz, B.; Mosakowska, K.; Cana, I.; Dobrin, I.; Lautaru, A.; Manescu, G.; Samoila, N.; Lacatus, M.; Apostoie, A.; Prunoiu, M.; Tilinca, M.; Budeanu, A.; Nedelcu, C.; Dumitrache, N.; Boeru, L.; Zhuravleva, E.; Gundova, M.; Hoffmannova, J.; Svitkova, M.; Pekarova, T.; Ujacka, K.; Zsoriova, T.; Kubincova, K.; Jankovicova, Z.; Talliard, C.; Tyumbu, N.; Mngoma, N.; Kannemeyer, M.; Mostert, J.; Page, A.; Krahenbuhl, C.; Tredoux, C.; Hendricks, L.; Oliver, S.; Le Grange, M.; Naidoo, V.; Bae, Y.; Kim, H.; Lee, J.; Yu, N.; An, S.; Kim, E.; Yang, K.; Woo, J.; Kim, S.; Rasck, J.; Smetana, S.; Ajax, K.; Bylander, L.; Lindberg, A.; Dellborg, H.; Hultsberg-Olsson, G.; Harsmar, K.; Knutsson, A.; Håkansson, L.; Kåveryd-Holmström, M.; Lundmark, L. M.; Norrfors, B.; Löf, P.; Skoglund, K.; Torgersruud, M.; Johansson, K.; Mattsson, A.; Quist, M.; Haglund, P.; Lundell, L.; Gunvasdotter, S.; Rangman, B.; Liu, R.; Shi, J.; Förstedt, G.; Nylund, L.; Welin-Berger, B.; Nilsson, O.; Garcia-Värlid, A.; Forlenza, R.; Kaminska, K.; Nagorna, T.; Cottam, V.; Harper, R.; Gilchrist, M.; Musanhu, R.; Mackin, A.; Turner, A.; Willetts, S.; Cadd, A.; Evans, J.; Young, G.; Sevillano, A.; Brodie, K.; Eccles, A.; Kelly, S.; Doughty, A.; Gray, J.; Gibson, M.; Finlayson, M.; Domingo, D.; Brazee, L.; Renaud, K.; Doman, A.; Meyer, R.; Beatty, J.; Morgan, T.; Rodas, E.; Campbell, D.; Mcquarrie, M.; Battistelli, E.; Eisenbraun, P.; Farley, R.; Park, H.; Dwyer, J.; Adams, K.; Schneider, W.; Barbour, C.; Whyne, E.; Budzinski, S.; Craig, M.; Gilley Elmore, J.; Scott, D.; Bellini, S.; Pepper, M.; Gunderson, K.; Stipek, I.; Schwarz, L.; Watkins, K.; Moore, V.; Palao, A.; Keane-Richmond, P.; Franklin, L.; Ward, L.; Kostedt, G.; Bailey, S.; Hollenweger, L.; Solomon, A.; Johnson, D.; Gloer, K.; Meyer, M.; Boleyn, M.; Nieters, D.; Humphrey, K.; Bohn, A.; Mueller, G.; Mckenzie, H.; Edwards, T.; Velky, J.; Cole, C.; Diederick, M.; Burg, S.; Coulson, T.; Karunaratne, K.; Gunasekera, R.; Cook, S.; Fisher, S.; Garrison, K.; Passey, L.; Kuykendall, K.; Luck, K.; Ramia, L.; Joan, H.; Reynoso, F.; Farley, M.; Shuman, S.; Santana-Fernandes, E.; Ventimiglia, A.; Steele, V.; Gers, L.; Brown, P.; Wilson, J.; Freebersyser, J.; Reno, M.; Buettner, N.; McGovern, M.; Hubbard, T.; Elmore, H.; Payne, D.; Mccann, M.; Decker, S.; Sharp, A.; Forgey, E.; Broussard, E.; Juett, U.; Siddiqui, A.
2017-01-01
We evaluated whether rivaroxaban alone or in combination with aspirin would be more effective than aspirin alone for secondary cardiovascular prevention. In this double-blind trial, we randomly assigned 27,395 participants with stable atherosclerotic vascular disease to receive rivaroxaban (2.5 mg
Inferring gene networks from discrete expression data
Zhang, L.
2013-07-18
The modeling of gene networks from transcriptional expression data is an important tool in biomedical research to reveal signaling pathways and to identify treatment targets. Current gene network modeling is primarily based on the use of Gaussian graphical models applied to continuous data, which give a closedformmarginal likelihood. In this paper,we extend network modeling to discrete data, specifically data from serial analysis of gene expression, and RNA-sequencing experiments, both of which generate counts of mRNAtranscripts in cell samples.We propose a generalized linear model to fit the discrete gene expression data and assume that the log ratios of the mean expression levels follow a Gaussian distribution.We restrict the gene network structures to decomposable graphs and derive the graphs by selecting the covariance matrix of the Gaussian distribution with the hyper-inverse Wishart priors. Furthermore, we incorporate prior network models based on gene ontology information, which avails existing biological information on the genes of interest. We conduct simulation studies to examine the performance of our discrete graphical model and apply the method to two real datasets for gene network inference. © The Author 2013. Published by Oxford University Press. All rights reserved.
An essay on discrete foundations for physics
International Nuclear Information System (INIS)
Noyes, H.P.; McGoveran, D.O.
1988-01-01
We base our theory of physics and cosmology on the five principles of finiteness, discreteness, finite computability, absolute non- uniqueness, and strict construction. Our modeling methodology starts from the current practice of physics, constructs a self-consistent representation based on the ordering operator calculus and provides rules of correspondence that allow us to test the theory by experiment. We use program universe to construct a growing collection of bit strings whose initial portions (labels) provide the quantum numbers that are conserved in the events defined by the construction. The labels are followed by content strings which are used to construct event-based finite and discrete coordinates. On general grounds such a theory has a limiting velocity, and positions and velocities do not commute. We therefore reconcile quantum mechanics with relativity at an appropriately fundamental stage in the construction. We show that events in different coordinate systems are connected by the appropriate finite and discrete version of the Lorentz transformation, that 3-momentum is conserved in events, and that this conservation law is the same as the requirement that different paths can ''interfere'' only when they differ by an integral number of deBroglie wavelengths. 38 refs., 12 figs., 3 tabs
Police investigations: discretion denied yet undeniably exercised
Belur, J.; Tilley, N.; Osrin, D.; Daruwalla, N.; Kumar, M.; Tiwari, V.
2014-01-01
Police investigations involve determining whether a crime has been committed, and if so what type of crime, who has committed it and whether there is the evidence to charge the perpetrators. Drawing on fieldwork in Delhi and Mumbai, this paper explores how police investigations unfolded in the specific context of women’s deaths by burning in India. In particular, it focuses on the use of discretion despite its denial by those exercising it. In India, there are distinctive statutes relating to women’s suspicious deaths, reflecting the widespread expectation that the bride’s family will pay a dowry to the groom’s family and the tensions to which this may on occasion give rise in the early years of a marriage. Often, there are conflicting claims influencing how the woman’s death is classified. These in turn affect police investigation. The nature and direction of police discretion in investigating women’s deaths by burning reflect in part the unique nature of the legislation and the particular sensitivities in relation to these types of death. They also highlight processes that are liable to be at work in any crime investigation. It was found that police officers exercised unacknowledged discretion at seven specific points in the investigative process, with potentially significant consequences for the achievement of just outcomes: first response, recording the victim’s ‘dying declaration’, inquest, registering of the ‘First Information Report’, collecting evidence, arrest and framing of the charges. PMID:26376482
Meshes optimized for discrete exterior calculus (DEC).
Energy Technology Data Exchange (ETDEWEB)
Mousley, Sarah C. [Univ. of Illinois, Urbana-Champaign, IL (United States); Deakin, Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knupp, Patrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, Scott A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-12-01
We study the optimization of an energy function used by the meshing community to measure and improve mesh quality. This energy is non-traditional because it is dependent on both the primal triangulation and its dual Voronoi (power) diagram. The energy is a measure of the mesh's quality for usage in Discrete Exterior Calculus (DEC), a method for numerically solving PDEs. In DEC, the PDE domain is triangulated and this mesh is used to obtain discrete approximations of the continuous operators in the PDE. The energy of a mesh gives an upper bound on the error of the discrete diagonal approximation of the Hodge star operator. In practice, one begins with an initial mesh and then makes adjustments to produce a mesh of lower energy. However, we have discovered several shortcomings in directly optimizing this energy, e.g. its non-convexity, and we show that the search for an optimized mesh may lead to mesh inversion (malformed triangles). We propose a new energy function to address some of these issues.
Quantum cosmology based on discrete Feynman paths
International Nuclear Information System (INIS)
Chew, Geoffrey F.
2002-01-01
Although the rules for interpreting local quantum theory imply discretization of process, Lorentz covariance is usually regarded as precluding time quantization. Nevertheless a time-discretized quantum representation of redshifting spatially-homogeneous universe may be based on discrete-step Feynman paths carrying causal Lorentz-invariant action--paths that not only propagate the wave function but provide a phenomenologically-promising elementary-particle Hilbert-space basis. In a model under development, local path steps are at Planck scale while, at a much larger ''wave-function scale'', global steps separate successive wave-functions. Wave-function spacetime is but a tiny fraction of path spacetime. Electromagnetic and gravitational actions are ''at a distance'' in Wheeler-Feynman sense while strong (color) and weak (isospin) actions, as well as action of particle motion, are ''local'' in a sense paralleling the action of local field theory. ''Nonmaterial'' path segments and ''trivial events'' collaborate to define energy and gravity. Photons coupled to conserved electric charge enjoy privileged model status among elementary fermions and vector bosons. Although real path parameters provide no immediate meaning for ''measurement'', the phase of the complex wave function allows significance for ''information'' accumulated through ''gentle'' electromagnetic events involving charged matter and ''soft'' photons. Through its soft-photon content the wave function is an ''information reservoir''
An essay on discrete foundations for physics
International Nuclear Information System (INIS)
Noyes, H.P.; McGoveran, D.O.
1988-07-01
We base our theory of physics and cosmology on the five principles of finiteness, discreteness, finite computability, absolute non-uniqueness, and strict construction. Our modeling methodology starts from the current practice of physics, constructs a self-consistent representation based on the ordering operator calculus and provides rules of correspondence that allow us to test the theory by experiment. We use program universe to construct a growing collection of bit strings whose initial portions (labels) provide the quantum numbers that are conserved in the events defined by the construction. The labels are followed by content strings which are used to construct event-based finite and discrete coordinates. On general grounds such a theory has a limiting velocity, and positions and velocities do not commute. We therefore reconcile quantum mechanics with relativity at an appropriately fundamental stage in the construction. We show that events in different coordinate systems are connected by the appropriate finite and discrete version of the Lorentz transformation, that 3-momentum is conserved in events, and that this conservation law is the same as the requirement that different paths can ''interfere'' only when they differ by an integral number of deBroglie wavelengths. 38 refs., 12 figs., 3 tabs
An essay on discrete foundations for physics
Energy Technology Data Exchange (ETDEWEB)
Noyes, H.P.; McGoveran, D.O.
1988-07-01
We base our theory of physics and cosmology on the five principles of finiteness, discreteness, finite computability, absolute non-uniqueness, and strict construction. Our modeling methodology starts from the current practice of physics, constructs a self-consistent representation based on the ordering operator calculus and provides rules of correspondence that allow us to test the theory by experiment. We use program universe to construct a growing collection of bit strings whose initial portions (labels) provide the quantum numbers that are conserved in the events defined by the construction. The labels are followed by content strings which are used to construct event-based finite and discrete coordinates. On general grounds such a theory has a limiting velocity, and positions and velocities do not commute. We therefore reconcile quantum mechanics with relativity at an appropriately fundamental stage in the construction. We show that events in different coordinate systems are connected by the appropriate finite and discrete version of the Lorentz transformation, that 3-momentum is conserved in events, and that this conservation law is the same as the requirement that different paths can ''interfere'' only when they differ by an integral number of deBroglie wavelengths. 38 refs., 12 figs., 3 tabs.
An essay on discrete foundations for physics
Energy Technology Data Exchange (ETDEWEB)
Noyes, H.P.; McGoveran, D.O.
1988-10-05
We base our theory of physics and cosmology on the five principles of finiteness, discreteness, finite computability, absolute non- uniqueness, and strict construction. Our modeling methodology starts from the current practice of physics, constructs a self-consistent representation based on the ordering operator calculus and provides rules of correspondence that allow us to test the theory by experiment. We use program universe to construct a growing collection of bit strings whose initial portions (labels) provide the quantum numbers that are conserved in the events defined by the construction. The labels are followed by content strings which are used to construct event-based finite and discrete coordinates. On general grounds such a theory has a limiting velocity, and positions and velocities do not commute. We therefore reconcile quantum mechanics with relativity at an appropriately fundamental stage in the construction. We show that events in different coordinate systems are connected by the appropriate finite and discrete version of the Lorentz transformation, that 3-momentum is conserved in events, and that this conservation law is the same as the requirement that different paths can ''interfere'' only when they differ by an integral number of deBroglie wavelengths. 38 refs., 12 figs., 3 tabs.
Physical models on discrete space and time
International Nuclear Information System (INIS)
Lorente, M.
1986-01-01
The idea of space and time quantum operators with a discrete spectrum has been proposed frequently since the discovery that some physical quantities exhibit measured values that are multiples of fundamental units. This paper first reviews a number of these physical models. They are: the method of finite elements proposed by Bender et al; the quantum field theory model on discrete space-time proposed by Yamamoto; the finite dimensional quantum mechanics approach proposed by Santhanam et al; the idea of space-time as lattices of n-simplices proposed by Kaplunovsky et al; and the theory of elementary processes proposed by Weizsaecker and his colleagues. The paper then presents a model proposed by the authors and based on the (n+1)-dimensional space-time lattice where fundamental entities interact among themselves 1 to 2n in order to build up a n-dimensional cubic lattice as a ground field where the physical interactions take place. The space-time coordinates are nothing more than the labelling of the ground field and take only discrete values. 11 references
Discrete dynamic modeling of cellular signaling networks.
Albert, Réka; Wang, Rui-Sheng
2009-01-01
Understanding signal transduction in cellular systems is a central issue in systems biology. Numerous experiments from different laboratories generate an abundance of individual components and causal interactions mediating environmental and developmental signals. However, for many signal transduction systems there is insufficient information on the overall structure and the molecular mechanisms involved in the signaling network. Moreover, lack of kinetic and temporal information makes it difficult to construct quantitative models of signal transduction pathways. Discrete dynamic modeling, combined with network analysis, provides an effective way to integrate fragmentary knowledge of regulatory interactions into a predictive mathematical model which is able to describe the time evolution of the system without the requirement for kinetic parameters. This chapter introduces the fundamental concepts of discrete dynamic modeling, particularly focusing on Boolean dynamic models. We describe this method step-by-step in the context of cellular signaling networks. Several variants of Boolean dynamic models including threshold Boolean networks and piecewise linear systems are also covered, followed by two examples of successful application of discrete dynamic modeling in cell biology.
Discrete phase space based on finite fields
International Nuclear Information System (INIS)
Gibbons, Kathleen S.; Hoffman, Matthew J.; Wootters, William K.
2004-01-01
The original Wigner function provides a way of representing in phase space the quantum states of systems with continuous degrees of freedom. Wigner functions have also been developed for discrete quantum systems, one popular version being defined on a 2Nx2N discrete phase space for a system with N orthogonal states. Here we investigate an alternative class of discrete Wigner functions, in which the field of real numbers that labels the axes of continuous phase space is replaced by a finite field having N elements. There exists such a field if and only if N is a power of a prime; so our formulation can be applied directly only to systems for which the state-space dimension takes such a value. Though this condition may seem limiting, we note that any quantum computer based on qubits meets the condition and can thus be accommodated within our scheme. The geometry of our NxN phase space also leads naturally to a method of constructing a complete set of N+1 mutually unbiased bases for the state space
Hybrid discrete choice models: Gained insights versus increasing effort.
Mariel, Petr; Meyerhoff, Jürgen
2016-10-15
Hybrid choice models expand the standard models in discrete choice modelling by incorporating psychological factors as latent variables. They could therefore provide further insights into choice processes and underlying taste heterogeneity but the costs of estimating these models often significantly increase. This paper aims at comparing the results from a hybrid choice model and a classical random parameter logit. Point of departure for this analysis is whether researchers and practitioners should add hybrid choice models to their suite of models routinely estimated. Our comparison reveals, in line with the few prior studies, that hybrid models gain in efficiency by the inclusion of additional information. The use of one of the two proposed approaches, however, depends on the objective of the analysis. If disentangling preference heterogeneity is most important, hybrid model seems to be preferable. If the focus is on predictive power, a standard random parameter logit model might be the better choice. Finally, we give recommendations for an adequate use of hybrid choice models based on known principles of elementary scientific inference. Copyright © 2016 Elsevier B.V. All rights reserved.
Frequency Weighted Model Order Reduction Technique and Error Bounds for Discrete Time Systems
Directory of Open Access Journals (Sweden)
Muhammad Imran
2014-01-01
for whole frequency range. However, certain applications (like controller reduction require frequency weighted approximation, which introduce the concept of using frequency weights in model reduction techniques. Limitations of some existing frequency weighted model reduction techniques include lack of stability of reduced order models (for two sided weighting case and frequency response error bounds. A new frequency weighted technique for balanced model reduction for discrete time systems is proposed. The proposed technique guarantees stable reduced order models even for the case when two sided weightings are present. Efficient technique for frequency weighted Gramians is also proposed. Results are compared with other existing frequency weighted model reduction techniques for discrete time systems. Moreover, the proposed technique yields frequency response error bounds.
Adaptive Neural Tracking Control for Discrete-Time Switched Nonlinear Systems with Dead Zone Inputs
Directory of Open Access Journals (Sweden)
Jidong Wang
2017-01-01
Full Text Available In this paper, the adaptive neural controllers of subsystems are proposed for a class of discrete-time switched nonlinear systems with dead zone inputs under arbitrary switching signals. Due to the complicated framework of the discrete-time switched nonlinear systems and the existence of the dead zone, it brings about difficulties for controlling such a class of systems. In addition, the radial basis function neural networks are employed to approximate the unknown terms of each subsystem. Switched update laws are designed while the parameter estimation is invariable until its corresponding subsystem is active. Then, the closed-loop system is stable and all the signals are bounded. Finally, to illustrate the effectiveness of the proposed method, an example is employed.
A Lax pair of the discrete Euler top
International Nuclear Information System (INIS)
Kimura, Kinji
2017-01-01
We proposed the discrete Euler top in 2000. In that paper, exact solutions and conserved quantities are described. However, a Lax pair of our proposed discrete Euler top is not contained. Moreover, the Lax pair is still unknown. In this paper, from a generalized eigenvalue problem, we obtain the Lax pair of the discrete Euler top. (paper)
A Variational Approach to Perturbed Discrete Anisotropic Equations
Directory of Open Access Journals (Sweden)
Amjad Salari
2016-01-01
Full Text Available We continue the study of discrete anisotropic equations and we will provide new multiplicity results of the solutions for a discrete anisotropic equation. We investigate the existence of infinitely many solutions for a perturbed discrete anisotropic boundary value problem. The approach is based on variational methods and critical point theory.
A Baecklund transformation between two integrable discrete hungry systems
International Nuclear Information System (INIS)
Fukuda, Akiko; Yamamoto, Yusaku; Iwasaki, Masashi; Ishiwata, Emiko; Nakamura, Yoshimasa
2011-01-01
The discrete hungry Toda (dhToda) equation and the discrete hungry Lotka-Volterra (dhLV) system are known as integrable discrete hungry systems. In this Letter, through finding the LR transformations associated with the dhToda equation and the dhLV system, we present a Baecklund transformation between these integrable systems.
Finite-dimensional reductions of the discrete Toda chain
Kazakova, T. G.
2004-08-01
The problem of construction of integrable boundary conditions for the discrete Toda chain is considered. The restricted chains for properly chosen closure conditions are reduced to the well-known discrete Painlevé equations dPIII, dPV, dPVI. Lax representations for these discrete Painlevé equations are found.
Discrete frequency identification using the HP 5451B Fourier analyser
International Nuclear Information System (INIS)
Holland, L.; Barry, P.
1977-01-01
The frequency analysis by the HP5451B discrete frequency Fourier analyser is studied. The advantages of cross correlation analysis to identify discrete frequencies in a background noise are discussed in conjuction with the elimination of aliasing and wraparound error. Discrete frequency identification is illustrated by a series of graphs giving the results of analysing 'electrical' and 'acoustical' white noise and sinusoidal signals [pt
Mittag-Leffler function for discrete fractional modelling
Directory of Open Access Journals (Sweden)
Guo-Cheng Wu
2016-01-01
Full Text Available From the difference equations on discrete time scales, this paper numerically investigates one discrete fractional difference equation in the Caputo delta’s sense which has an explicit solution in form of the discrete Mittag-Leffler function. The exact numerical values of the solutions are given in comparison with the truncated Mittag-Leffler function.
Process algebra with timing: Real time and discrete time
Baeten, J.C.M.; Middelburg, C.A.
1999-01-01
We present real time and discrete time versions of ACP with absolute timing and relative timing. The startingpoint is a new real time version with absolute timing, called ACPsat , featuring urgent actions and a delay operator. The discrete time versions are conservative extensions of the discrete
DEFF Research Database (Denmark)
Mahmoudi, Zeinab; Boiroux, Dimitri; Hagdrup, Morten
2016-01-01
was modelled by a Gaussian random walk. We used a continuous-discrete extended Kalman filter for the fault detection, based on the statistical tests of the filter innovation and the 90-min prediction residuals of the sensor measurements. The spike detection had a sensitivity of 93% and a specificity of 100...
Dissecting the circle, at random*
Directory of Open Access Journals (Sweden)
Curien Nicolas
2014-01-01
Full Text Available Random laminations of the disk are the continuous limits of random non-crossing configurations of regular polygons. We provide an expository account on this subject. Initiated by the work of Aldous on the Brownian triangulation, this field now possesses many characters such as the random recursive triangulation, the stable laminations and the Markovian hyperbolic triangulation of the disk. We will review the properties and constructions of these objects as well as the close relationships they enjoy with the theory of continuous random trees. Some open questions are scattered along the text.
Schunert, Sebastian; Wang, Yaqi; Gleicher, Frederick; Ortensi, Javier; Baker, Benjamin; Laboure, Vincent; Wang, Congjian; DeHart, Mark; Martineau, Richard
2017-06-01
This work presents a flexible nonlinear diffusion acceleration (NDA) method that discretizes both the SN transport equation and the diffusion equation using the discontinuous finite element method (DFEM). The method is flexible in that the diffusion equation can be discretized on a coarser mesh with the only restriction that it is nested within the transport mesh and the FEM shape function orders of the two equations can be different. The consistency of the transport and diffusion solutions at convergence is defined by using a projection operator mapping the transport into the diffusion FEM space. The diffusion weak form is based on the modified incomplete interior penalty (MIP) diffusion DFEM discretization that is extended by volumetric drift, interior face, and boundary closure terms. In contrast to commonly used coarse mesh finite difference (CMFD) methods, the presented NDA method uses a full FEM discretized diffusion equation for acceleration. Suitable projection and prolongation operators arise naturally from the FEM framework. Via Fourier analysis and numerical experiments for a one-group, fixed source problem the following properties of the NDA method are established for structured quadrilateral meshes: (1) the presented method is unconditionally stable and effective in the presence of mild material heterogeneities if the same mesh and identical shape functions either of the bilinear or biquadratic type are used, (2) the NDA method remains unconditionally stable in the presence of strong heterogeneities, (3) the NDA method with bilinear elements extends the range of effectiveness and stability by a factor of two when compared to CMFD if a coarser diffusion mesh is selected. In addition, the method is tested for solving the C5G7 multigroup, eigenvalue problem using coarse and fine mesh acceleration. While NDA does not offer an advantage over CMFD for fine mesh acceleration, it reduces the iteration count required for convergence by almost a factor of two in
Acceptance tail method for generating unimodal random variables
Shmerling, Efraim
2016-10-01
A universal method for generating continuous random variables with unbounded range and infinite-valued discrete random variables is presented. It is shown how the method can be implemented for generating univariate unimodal continuous random variables. Efficiency of the presented method for generating gamma random variables in terms of generation time is compared with the efficiency of all widely utilized algorithms developed to date, and the superior efficiency of the presented method is proved.
Rational solutions of the discrete time Toda lattice and the alternate discrete Painleve II equation
International Nuclear Information System (INIS)
Common, Alan K; Hone, Andrew N W
2008-01-01
The Yablonskii-Vorob'ev polynomials y n (t), which are defined by a second-order bilinear differential-difference equation, provide rational solutions of the Toda lattice. They are also polynomial tau-functions for the rational solutions of the second Painleve equation (P II ). Here we define two-variable polynomials Y n (t, h) on a lattice with spacing h, by considering rational solutions of the discrete time Toda lattice as introduced by Suris. These polynomials are shown to have many properties that are analogous to those of the Yablonskii-Vorob'ev polynomials, to which they reduce when h = 0. They also provide rational solutions for a particular discretization of P II , namely the so-called alternate discrete P II , and this connection leads to an expression in terms of the Umemura polynomials for the third Painleve equation (P III ). It is shown that the Baecklund transformation for the alternate discrete Painleve equation is a symplectic map, and the shift in time is also symplectic. Finally we present a Lax pair for the alternate discrete P II , which recovers Jimbo and Miwa's Lax pair for P II in the continuum limit h → 0
Discrete Sine Transform-Based Interpolation Filter for Video Compression
Directory of Open Access Journals (Sweden)
MyungJun Kim
2017-11-01
Full Text Available Fractional pixel motion compensation in high-efficiency video coding (HEVC uses an 8-point filter and a 7-point filter, which are based on the discrete cosine transform (DCT, for the 1/2-pixel and 1/4-pixel interpolations, respectively. In this paper, discrete sine transform (DST-based interpolation filters (DST-IFs are proposed for fractional pixel motion compensation in terms of coding efficiency improvement. Firstly, a performance of the DST-based interpolation filters (DST-IFs using 8-point and 7-point filters for the 1/2-pixel and 1/4-pixel interpolations is compared with that of the DCT-based IFs (DCT-IFs using 8-point and 7-point filters for the 1/2-pixel and 1/4-pixel interpolations, respectively, for fractional pixel motion compensation. Finally, the DST-IFs using 12-point and 11-point filters for the 1/2-pixel and 1/4-pixel interpolations, respectively, are proposed only for bi-directional motion compensation in terms of the coding efficiency. The 8-point and 7-point DST-IF methods showed average Bjøntegaard Delta (BD-rate reductions of 0.7% and 0.3% in the random access (RA and low delay B (LDB configurations, respectively, in HEVC. The 12-point and 11-point DST-IF methods showed average BD-rate reductions of 1.4% and 1.2% in the RA and LDB configurations for the Luma component, respectively, in HEVC.
Full-frame compression of discrete wavelet and cosine transforms
Lo, Shih-Chung B.; Li, Huai; Krasner, Brian; Freedman, Matthew T.; Mun, Seong K.
1995-04-01
At the foreground of computerized radiology and the filmless hospital are the possibilities for easy image retrieval, efficient storage, and rapid image communication. This paper represents the authors' continuous efforts in compression research on full-frame discrete wavelet (FFDWT) and full-frame discrete cosine transforms (FFDCT) for medical image compression. Prior to the coding, it is important to evaluate the global entropy in the decomposed space. It is because of the minimum entropy, that a maximum compression efficiency can be achieved. In this study, each image was split into the top three most significant bit (MSB) and the remaining remapped least significant bit (RLSB) images. The 3MSB image was compressed by an error-free contour coding and received an average of 0.1 bit/pixel. The RLSB image was either transformed to a multi-channel wavelet or the cosine transform domain for entropy evaluation. Ten x-ray chest radiographs and ten mammograms were randomly selected from our clinical database and were used for the study. Our results indicated that the coding scheme in the FFDCT domain performed better than in FFDWT domain for high-resolution digital chest radiographs and mammograms. From this study, we found that decomposition efficiency in the DCT domain for relatively smooth images is higher than that in the DWT. However, both schemes worked just as well for low resolution digital images. We also found that the image characteristics of the `Lena' image commonly used in the compression literature are very different from those of radiological images. The compression outcome of the radiological images can not be extrapolated from the compression result based on the `Lena.'
... is an MRE? Is an MRE shelf stable? What foods are packaged in retort packages? What is aseptic ... type of package is used for aseptic processing? What foods are packaged in aseptic packages? Can I microwave ...
Liu, Nan; Wen, Xiao-Yong
2018-03-01
Under consideration in this paper is the Kaup-Newell (KN) lattice equation which is an integrable discretization of the KN equation. Infinitely, many conservation laws and discrete N-fold Darboux transformation (DT) for this system are constructed and established based on its Lax representation. Via the resulting N-fold DT, the discrete multi-dark soliton solutions in terms of determinants are derived from non-vanishing background. Propagation and elastic interaction structures of such solitons are shown graphically. Overtaking interaction phenomena between/among the two, three and four solitons are discussed. Numerical simulations are used to explore their dynamical behaviors of such multi-dark solitons. Numerical results show that their evolutions are stable against a small noise. Results in this paper might be helpful for understanding the propagation of nonlinear Alfvén waves in plasmas.
Pharmaceuticals labelled with stable isotopes
International Nuclear Information System (INIS)
Krumbiegel, P.
1986-11-01
The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13 C, 15 N, and 2 H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2 H, 13 C, and 15 N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)