Search results for "STATISTICS"
showing 10 items of 7671 documents
Convergence of Markovian Stochastic Approximation with discontinuous dynamics
2016
This paper is devoted to the convergence analysis of stochastic approximation algorithms of the form $\theta_{n+1} = \theta_n + \gamma_{n+1} H_{\theta_n}({X_{n+1}})$, where ${\left\{ {\theta}_n, n \in {\mathbb{N}} \right\}}$ is an ${\mathbb{R}}^d$-valued sequence, ${\left\{ {\gamma}_n, n \in {\mathbb{N}} \right\}}$ is a deterministic stepsize sequence, and ${\left\{ {X}_n, n \in {\mathbb{N}} \right\}}$ is a controlled Markov chain. We study the convergence under weak assumptions on smoothness-in-$\theta$ of the function $\theta \mapsto H_{\theta}({x})$. It is usually assumed that this function is continuous for any $x$; in this work, we relax this condition. Our results are illustrated by c…
Probabilistic interpretation of the Calderón problem
2017
In this paper, we use the theory of symmetric Dirichlet forms to give a probabilistic interpretation of Calderon's inverse conductivity problem in terms of reflecting diffusion processes and their corresponding boundary trace processes. This probabilistic interpretation comes in three equivalent formulations which open up novel perspectives on the classical question of unique determinability of conductivities from boundary data. We aim to make this work accessible to both readers with a background in stochastic process theory as well as researchers working on deterministic methods in inverse problems.
Coordination and profit rate maximization
1995
We study the effects over the coordination between firms of the choice of another objectivefunction for the firm: the profit rate maximization which seems to be closer to business practice than the classical pure profit maximization. After recalling the effect of the new objective function over the optimum (the optimal production is lower), two cases are considered : perfect competition (the price signal disappear), and duopoly-oligopoly (the functions of reactions may vanish). (FR) Nous étudions les effets sur la coordination inter-firmes du choix d'une autre fonction objectif pour la firme: la maximisation du taux de profit qui semble être plus proche de la pratique des affaires que la cl…
Guaranteed tuning of PID controllers for parametric uncertain systems
2004
This paper presents a methodology for tuning the controller of a parametric uncertain plant in order to guarantee the satisfaction of specifications. These specifications are defined by means of an interval reference model that represents the set of satisfactory time or frequency behaviors. The controller synthesis is then formulated as a set-inclusion problem in the frequency domain. Interval techniques for the solution of constraint satisfaction problems are applied to design fixed-structure controllers in a guaranteed manner. In particular, PID controllers are considered since they are widely used in industry.
Precise vs General Feedback in Reducing Field-Dependence
1980
Summary.-To investigate the effect of feedback on performance of the Rod-and-frame Test the standard test procedure mas altered. The result of the alteration was a procedure which was called the Rod-and-frame Test as a Learning Task. On this task the subiect has to adjust the rod to the vertical twice in succession from each tilting position, whereby he is permitred a maximum of 10 trials in each tilting position and a range of tolerance of elo. After each trial the subject is given feedback about his performance. An experiment was conducted with 30 male and 30 female students to investigate whether a precise feedback giving both the direction and the degree of the rod's deviation from the …
Modelisation of the labor demand on a sample of Tunisian industrial firms
1993
The purpose of this paper is a modelisation of the demand labor in Tunisian industrial firms. The determination of labor input is deduced from a classical decisional problem of profit maximisation under technical constraints and constraints reported from the markets in relation with the labor market. Different specifications of the labor demand model were formulated and estimated on a sample of Tunisian industrial firms (on panel data)
The HOTELLING model : contributions and limits (application to the case where strategic variables are localizations and prices)
1991
Ix modèle de H O T E L L I N G a fait l'objet de nombreuses discussions. O n sait en particulier que lorsque le domaine des paramètres de localisation s'élargit et pour des coûts de transport linéaires, le prix d'équilibre en stratégie pure n'existe plus. I æ coût de transport linéaire et les discontinuités desfonctions sont responsables de l'absence d'équilibre. L'objet, de cette étude est de démontrer l'existence d'un équilibre à partir d'un jeu séquentiel. Toutd'abord les firmes choisisent leur localisation en anticipant des prix d'équilibre. Après avoir vérifié que, dans la pratique des affaires, les coûts de transport peuvent être soit de forme concave, soit de forme convexe, on introd…
Configuration optimale des aires de marché et coûts de transport
1991
La théorie des Places Centrales étudiée par LÖSCH (4) et CHRISTALLER (5) a pour objet l'examen et la construction d'un paysage hiérarchisé. Celui-ci est basé sur un système d'aires de marché qui possèdent des configurations précises (hexagonales et carrées principalement). En fait raire de marché correspond à la zone d'influence d'un offreur. LÖSCH (4, p 130) a supposé que la libre entrée de firmes indépendantes localisées sur une plaine où sont situés des demandeurs équidistants entraine une transformation des aires circulaires en aires hexagonales et ainsi une maximisation du nombre de firmes par unité d'aire. HARTWICK (2) examine analytiquement le théorème de LÖSCH concernant les aires d…
Controllable Solid Rocket Motor Nozzle Operations in Conditions of Limited-Amplitude Fluctuations
2009
A nonlinear multi scale analysis of a controllable solid rocket motor operating in conditions ranging from high-amplitude fluctuations in combustion chamber to conditions lying in limit cycle is presented and the motor behavior subsequent to some relevant nozzle operations is investigated. Effects of acoustic-vorticity-entropy wave coupling, wave steepening, rotational/viscous flow losses, steep-fronted wave losses are taken into account and oscillatory energy losses in pintle-nozzle, unsteady combustion and chamber geometry changes resulting from grain regression are included. The analysis provides evidence that the unsteady energy balance and the motor wave amplitude evolution are influen…
EXPERIMENTAL VALIDATION OF A FINITE DIFFERENCES TROMBE WALL MODEL
1983
ABSTRACT The paper describes a finite differences Trombe wall model validation, based on experimental data recorded at a passive systems test station in Central Italy. The computer code has been checked step by step, due to the different reliability of the data and to the various algorithms used in the code. Thus, cloudy and clear nights with no thermocirculation were simulated and compared with experimental data, then evening hours with thermocirculation, but no sun and, finally, a full day was simulated and compared. Some inaccuracy has been found in the simulation of wind effect on outer glass convective heat transfer coefficient. The code, however, has been found to provide data in reas…