in this paper, weak defining hyperplanes and the anchor points in dea, as an important subset of the set of extreme efficient points of the production possibility set (pps), are used to construct unobserved dmus and in the long run to improve the envelopment of all observed dmus. there has been a surge of articles on improving envelopment in recent years. what has been done first is in constant...

Extreme events occur in many spatially extended dynamical systems, often devastatingly affecting human life, which makes their reliable prediction and efficient prevention highly desirable. We study the prediction and prevention of extreme events in a spatially extended system, a system of coupled FitzHugh-Nagumo units, in which extreme events occur in a spatially and temporally irregular way. ...

In spite of precautions to avoid the harmful effects of extreme events, we experience recurrently phenomena that overcome the preventive barriers. These barriers usually increase drastically right after the occurrence of such extreme events, but steadily decay in their absence. In this paper we consider a simple model that mimics the evolution of the protection barriers to study the efficiency ...

The range of a payoff function in an n-player finite strategic game is investigated using a novel approach, the notion of extreme points of a nonconvex set. A basic structural characteristic of a noncooperative payoff region is that any subregion must be non-strictly convex if it contains a relative neighborhood of a boundary point of the noncooperative payoff region. This can be proved efficie...

Double robust extreme ranked set sampling (DRERSS) and its properties for estimating the population median are suggested. The performance of DRERSS with respect to simple random sampling (SRS), ranked set sampling (RSS) and extreme ranked set sampling (ERSS) schemes is considered. Real data set that consist of heights of 346 students are used to evaluate the DRERSS method. It is found that when...

Climate is the most important factor which control desertification .In order to detect climate changes in desert zones, time trend analysis is applied to extreme indices in Kashan station using extreme climate index software (ECIS). Results show significant trends in extreme indices during the past decade 1995-2004 and the pronounced warming is associated with a negative trend in cold extremes....