Non-classical solutions of a continuum model for rock descriptions

The strain-gradient and non-Euclidean continuum theories are employed for construction of nonclassical solutions of continuum models.The linear approximation of both models’results in identical structures in terms of their kinematic and stress characteristics.The solutions obtained in this study exhibit a critical behaviour with respect to the external loading parameter.The conclusions are obtained based on an investigation of the solution for the scalar curvature in the non-Euclidean continuum theory.The proposed analysis enables us to use different theoretical approaches for description of rock critical behaviour under different loading conditions.

Assessment of the Elastic-Wave Well Treatment in Oil-Bearing Clastic and Carbonate Reservoirs

A set of techniques for well treatment aimed to enhance oil recovery are considered in the present study.These are based on the application of elastic waves of various types(dilation-wave,vibro-wave,or other acoustically induced effects).In such a context,a new technique is proposed to predict the effectiveness of the elastic-wave well treatment using the rank distribution according to Zipf’s law.It is revealed that,when the results of elastic wave well treatments are analyzed,groups of wells exploiting various geological deposits can differ in terms of their slope coefficients and free members.As the slope coefficient increases,the average increase in the well oil production rate(after the well treatment)becomes larger.An equation is obtained accordingly for estimating the slope coefficient in the Zipf’s equation from the frequency of the elastic wave.The obtained results demonstrate the applicability of the Zipf’s law in the analysis of the technological efficiency of elastic-wave well treatment methods.

Effective use of FibroTest to generate decision trees in hepatitis C

AIM:To assess the usefulness of FibroTest to forecast scores by constructing decision trees in patients with chronic hepatitis C.METHODS:We used the C4.5 classification algorithm to construct decision trees with data from 261 patients with chronic hepatitis C without a liver biopsy.The FibroTest attributes of age,gender,bilirubin,apolipoprotein,haptoglobin,α2 macroglobulin,and γ-glutamyl transpeptidase were used as predictors,and the FibroTest score as the target.For testing,a 10-fold cross validation was used.RESULTS:The overall classification error was 14.9%(accuracy 85.1%).FibroTest's cases with true scores of F0 and F4 were classified with very high accuracy(18/20 for F0,9/9 for F0-1 and 92/96 for F4) and the largest confusion centered on F3.The algorithm produced a set of compound rules out of the ten classification trees and was used to classify the 261 patients.The rules for the classification of patients in F0 and F4 were effective in more than 75% of the cases in which they were tested.CONCLUSION:The recognition of clinical subgroups should help to enhance our ability to assess differences in fibrosis scores in clinical studies and improve our understanding of fibrosis progression.

Robust estimation of time-dependent precision matrix with application to the cryptocurrency market

Most financial signals show time dependency that,combined with noisy and extreme events,poses serious problems in the parameter estimations of statistical models.Moreover,when addressing asset pricing,portfolio selection,and investment strategies,accurate estimates of the relationship among assets are as necessary as are delicate in a time-dependent context.In this regard,fundamental tools that increasingly attract research interests are precision matrix and graphical models,which are able to obtain insights into the joint evolution of financial quantities.In this paper,we present a robust divergence estimator for a time-varying precision matrix that can manage both the extreme events and time-dependency that affect financial time series.Furthermore,we provide an algorithm to handle parameter estimations that uses the“maximization–minimization”approach.We apply the methodology to synthetic data to test its performances.Then,we consider the cryptocurrency market as a real data application,given its remarkable suitability for the proposed method because of its volatile and unregulated nature.

On the Solution of One-Dimensional Ising Models

In this paper it is shown that the thermodynamic limit of the partition function of the statistical models under consideration on a one-dimensional lattice with an arbitrary finite number of interacting neighbors is expressed in terms of the principal eigenvalue of a matrix of finite size. The high sparseness of these matrices for any number of interactions makes it possible to perform an effective numerical analysis of the macro characteristics of these models.

Ergodicity and Invariance of Flows in Queuing Systems

In this paper, we investigate the flow of customers through queuing systems with randomly varying intensities. The analysis of the Kolmogorov-Chapman system of stationary equations for this model showed that it is not possible to construct a convenient symbolic solution. In this paper an attempt is made to circumvent this requirement by referring to the ergodicity theorems, which gives the conditions for the existence of the limit distribution in the service processes, but do not require knowledge of them.

ELECTROHYDRODYNAMIC DISPERSION OF DEFORMABLE AEROSOLS IN THE PRESENCE OF AN ELECTRIC FIELD AND CHEMICAL REACTION USING TAYLOR DISPERSION MODEL

Under the effects of electric field and chemical reaction, the problem of dispersion of aerosols in a poorly conducting fluid in a channel is solved analytically using the mixture theory together with a regular perturbation technique. It is shown that the aerosols are dispersed relative to a plane moving with the mean speed of atmospheric fluid as well as the mean speed of agglomeration of aerosol with a relative diffusion coefficient, called the Taylor dispersion coefficient. This coefficient is numerically computed and the results reveal that it increases with an increase in the electric number, but decreases with increasing porous parameter. The physical explanations for the phenomena are given in this article.

Existence of strong solutions in critical spaces for barotropic viscous fluids in larger spaces

This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N 2.We address the question of well-posedness for large data having critical Besov regularity.Our result improves the analysis of Danchin and of the author inasmuch as we may take initial density in B N p p,1 with 1 p < +∞.Our result relies on a new a priori estimate for the velocity,where we introduce a new unknown called effective velocity to weaken one of the couplings between the density and the velocity.In particular,our result is the first in which we obtain uniqueness without imposing hypothesis on the gradient of the density.

Identification of the Exchange Coefficient from Indirect Data for a Coupled Continuum Pipe-Flow Model

Calibration and identification of the exchange effect between the karst aquifers and the underlying conduit network are important issues in order to gain a better understanding of these hydraulic systems. Based on a coupled continuum pipe-flow(CCPF for short) model describing flows in karst aquifers, this paper is devoted to the identification of an exchange rate function, which models the hydraulic interaction between the fissured volume(matrix) and the conduit, from the Neumann boundary data, i.e., matrix/conduit seepage velocity. The authors formulate this parameter identification problem as a nonlinear operator equation and prove the compactness of the forward mapping. The stable approximate solution is obtained by two classic iterative regularization methods, namely,the Landweber iteration and Levenberg-Marquardt method. Numerical examples on noisefree and noisy data shed light on the appropriateness of the proposed approaches.

Between Algorithm and Model:Different Molecular Surface Definitions for the Poisson-Boltzmann Based Electrostatic Characterization of Biomolecules in Solution

The definition of a molecular surface which is physically sound and computationally efficient is a very interesting and long standing problem in the implicit solvent continuum modeling of biomolecular systems as well as in the molecular graphics field.In this work,two molecular surfaces are evaluated with respect to their suitability for electrostatic computation as alternatives to the widely used Connolly-Richards surface:the blobby surface,an implicit Gaussian atom centered surface,and the skin surface.As figures of merit,we considered surface differentiability and surface area continuity with respect to atom positions,and the agreement with explicit solvent simulations.Geometric analysis seems to privilege the skin to the blobby surface,and points to an unexpected relationship between the non connectedness of the surface,caused by interstices in the solute volume,and the surface area dependence on atomic centers.In order to assess the ability to reproduce explicit solvent results,specific software tools have been developed to enable the use of the skin surface in PoissonBoltzmann calculations with the DelPhi solver.The results indicate that the skin and Connolly surfaces have a comparable performance from this last point of view.

Categorical computation

In quantum computing, the computation is achieved by linear operators in or between Hilbert spaces. In this work, we explore a new computation scheme, in which the linear operators in quantum computing are replaced by (higher) functors between two (higher) categories. If from Turing computing to quantum computing is the first quantization of computation, then this new scheme can be viewed as the second quantization of computation. The fundamental problem in realizing this idea is how to realize a (higher) functor physically. We provide a theoretical idea of realizing (higher) functors physically based on the physics of topological orders.

Control and Nash Games with Mean Field Effect

Mean field theory has raised a lot of interest in the recent years (see in particular the results of Lasry-Lions in 2006 and 2007,of Gueant-Lasry-Lions in 2011,of HuangCaines-Malham in 2007 and many others).There are a lot of applications.In general,the applications concern approximating an infinite number of players with common behavior by a representative agent.This agent has to solve a control problem perturbed by a field equation,representing in some way the behavior of the average infinite number of agents.This approach does not lead easily to the problems of Nash equilibrium for a finite number of players,perturbed by field equations,unless one considers averaging within different groups,which has not been done in the literature,and seems quite challenging.In this paper,the authors approach similar problems with a different motivation which makes sense for control and also for differential games.Thus the systems of nonlinear partial differential equations with mean field terms,which have not been addressed in the literature so far,are considered here.

A new insight into the nature of seasonal variations in coordinate time series of GPS sites located near active faults

这研究在在他们的建模的活跃差错和方法附近定位的 GPS 地点的并列时间系列提供新卓见进季节的变化的性质。每月平均的并列时间系列为在活跃差错交叉区域附近位于的几个并置的 GPS 地点被分析，在到 Amurian 板和圣 Andreas 差错地区的附近的北边界的中央部分的靠近的最近。观察季节的变化被是著名 sine-Gordon 方程的答案之一的 breather 功能最好描述，这被结束。获得的结果建议在这种情况中，季节的变化的来源可以被独居的种类波浪的外观在差错交叉系统引起，它可以是当作承受地质的媒介的压缩扩展的波浪的品质上。基于统计测试，建议模型的适用性的限制被建立了。

Bellman Systems with Mean Field Dependent Dynamics

The authors deal with nonlinear elliptic and parabolic systems that are the Bellman like systems associated to stochastic differential games with mean field dependent dynamics. The key novelty of the paper is that they allow heavily mean field dependent dynamics. This in particular leads to a system of PDE's with critical growth,for which it is rare to have an existence and/or regularity result. In the paper,they introduce a structural assumptions that cover many cases in stochastic differential games with mean field dependent dynamics for which they are able to establish the existence of a weak solution. In addition,the authors present here a completely new method for obtaining the maximum/minimum principles for systems with critical growths,which is a starting point for further existence and also qualitative analysis.

Maximal Coupling of Euclidean Brownian Motions

We prove that the mirror coupling is the unique maximal Markovian coupling of two Euclidean Brownian motions starting from single points and discuss the connection between the uniqueness of maximalMarkovian coupling of Brownian motions and certain mass transportation problems.

PARAMETRIC OPTIMIZING ANALYSIS OF UNSTEADY STRUCTURES AND VISUALIZATION OF MULTIDIMENSIONAL DATA

The paper presents an approach to fast approximate estimation of conditions for spacetime structures appearing in the flows.The approach is based on combination of optimization problem computation with methods of data visual presentation.The visual presentation methods are applied for analysis of multidimensional array containing discrete result data.Optimization problem solution is implemented by parallel computation in a multitask form.For some cases,the approach allows to obtain for control parameter of considered problem the sought-for approximate dependence on characteristic parameters in a quasi-analytical form.