Systematic co-occurrence of tail correlation functions among max-stable processes

The tail correlation function (TCF) is one of the most popular bivariate extremal dependence measures that has entered the literature under various names. We study to what extent the TCF can distinguish between different classes of well-known max-stable processes and identify essentially different processes sharing the same TCF.Comment: 31 pages, 4 Tables, 5 Figure

Experimental Analysis of Algorithms for Coflow Scheduling

Modern data centers face new scheduling challenges in optimizing job-level performance objectives, where a significant challenge is the scheduling of highly parallel data flows with a common performance goal (e.g., the shuffle operations in MapReduce applications). Chowdhury and Stoica introduced the coflow abstraction to capture these parallel communication patterns, and Chowdhury et al. proposed effective heuristics to schedule coflows efficiently. In our previous paper, we considered the strongly NP-hard problem of minimizing the total weighted completion time of coflows with release dates, and developed the first polynomial-time scheduling algorithms with O(1)-approximation ratios. In this paper, we carry out a comprehensive experimental analysis on a Facebook trace and extensive simulated instances to evaluate the practical performance of several algorithms for coflow scheduling, including the approximation algorithms developed in our previous paper. Our experiments suggest that simple algorithms provide effective approximations of the optimal, and that the performance of our approximation algorithms is relatively robust, near optimal, and always among the best compared with the other algorithms, in both the offline and online settings.Comment: 29 pages, 8 figures, 11 table

Numerical solution of exterior Maxwell problems by Galerkin BEM and Runge-Kutta convolution quadrature

In this paper we consider time-dependent electromagnetic scattering problems from conducting objects. We discretize the time-domain electric field integral equation using Runge-Kutta convolution quadrature in time and a Galerkin method in space. We analyze the involved operators in the Laplace domain and obtain convergence results for the fully discrete scheme. Numerical experiments indicate the sharpness of the theoretical estimate

Low rank approximation of multidimensional data

In the last decades, numerical simulation has experienced tremendous improvements driven by massive growth of computing power. Exascale computing has been achieved this year and will allow solving ever more complex problems. But such large systems produce colossal amounts of data which leads to its own difficulties. Moreover, many engineering problems such as multiphysics or optimisation and control, require far more power that any computer architecture could achieve within the current scientific computing paradigm. In this chapter, we propose to shift the paradigm in order to break the curse of dimensionality by introducing decomposition to reduced data. We present an extended review of data reduction techniques and intends to bridge between applied mathematics community and the computational mechanics one. The chapter is organized into two parts. In the first one bivariate separation is studied, including discussions on the equivalence of proper orthogonal decomposition (POD, continuous framework) and singular value decomposition (SVD, discrete matrices). Then, in the second part, a wide review of tensor formats and their approximation is proposed. Such work has already been provided in the literature but either on separate papers or into a pure applied mathematics framework. Here, we offer to the data enthusiast scientist a description of Canonical, Tucker, Hierarchical and Tensor train formats including their approximation algorithms. When it is possible, a careful analysis of the link between continuous and discrete methods will be performed.IV Research and Transfer Plan of the University of SevillaInstitut CarnotJunta de AndalucíaIDEX program of the University of Bordeau

Comparison of some Reduced Representation Approximations

In the field of numerical approximation, specialists considering highly complex problems have recently proposed various ways to simplify their underlying problems. In this field, depending on the problem they were tackling and the community that are at work, different approaches have been developed with some success and have even gained some maturity, the applications can now be applied to information analysis or for numerical simulation of PDE's. At this point, a crossed analysis and effort for understanding the similarities and the differences between these approaches that found their starting points in different backgrounds is of interest. It is the purpose of this paper to contribute to this effort by comparing some constructive reduced representations of complex functions. We present here in full details the Adaptive Cross Approximation (ACA) and the Empirical Interpolation Method (EIM) together with other approaches that enter in the same category

Random Marked Sets

We aim to link random fields and marked point processes and therefore introduce a new class of stochastic processes which are defined on a random set in R^d. Unlike for random fields, the mark covariance function of a marked random set is in general not positive definite. This implies that in many situations the use of simple geostatistical methods appears to be questionable. Surprisingly, for a special class of processes based on Gaussian random fields, we do have positive definiteness for the corresponding mark covariance function and mark correlation function

Beiträge zur Theorie und Anwendung von Keim-Korn-Modellen mit konvexen Körnern

Gegenstand der Arbeit sind zufällige Mengen $Xi$ aus dem erweiterten Konvexring und zugehörige markierte Punktprozesse $Psi$ in $mathbb{R}^d$ mit Marken aus dem System der konvexen Körper. Es wird gezeigt, unter welchen Voraussetzungen an $Psi$ die zweite Produktdichte $varrho_S^{(2)}$ des durch $Xi$ induzierten zufälligen Oberflächenmaßes $S_{Xi}$ existiert und eine klassische Beziehung zwischen der Intensitätsfunktion von $S_{Xi}$ und der Ableitung der sphärischen Kontaktverteilungsfunktion von $Xi$ bei Null auf entsprechende Größen zweiter Ordnung übertragen werden kann. Mit Hilfe des so erhaltenen Zugangs wird $varrho_S^{(2)}$ für einige Beispiele bestimmt. Desweiteren werden spezielle markierte Punktprozesse $Psi$ betrachtet, die durch Verdünnung gemäß einer Methode nach Matérn aus einem markierten Poisson-Prozess hervorgehen. Als praktische Anwendung wird für zwei Proben eines Feuerbetons mit kugelförmigen Einschlüssen untersucht, welche Modelle für zufällige Systeme harter Kugeln zur Beschreibung geeignet sind

Link and Match Strategy Management in Building Graduate Competitiveness

This research aims to examine strategic management (Fred R David) link and match (Prosser & Quigley) in growing the competitiveness of graduates through strategy formulation, implementation, evaluation and control. A qualitative approach with a case study method was used in this research. Data collection was carried out through interviews, observation and documentation. Data analysis was conducted using the Miles and Huberman model and then tested through triangulation credibility, transferability, dependability and confirmability. The research results show that Vision and mission, external environmental analysis, future goals, implementation plans, and policies are part of the strategy formation process. The formulation of the link and match strategy involves all interested parties. Implement the link-and-match strategy by optimizing the formation of noble morals and character, increasing competence, optimizing cooperation, and forming entrepreneurship. Strategy evaluation and control are done through review, performance measurement and revision. The implications of this research provide new solutions for educational institutions, especially in increasing the competency of more competitive graduates