Citrus production has a great importance and position in Iran. The growth and sustainability of the agriculture sector is impossible without appropriate and effective risk identification and management. In this study, the main risks of citrus gardens were identified based on the Delphi method through questionnaires completed by 16 experts. Then, using the TOPSIS technique, the risks involved in...

The volatilities and correlations of the returns on a set of assets, risk factors or interest rates are summarized in a covariance matrix. This matrix lies at the heart of risk and return analysis. It contains all the information necessary to estimate the volatility of a portfolio, to simulate correlated values for its risk factors, to diversify investments and to obtain efficient portfolios th...

‎the global fom and gmres algorithms are among the effective‎ ‎methods to solve sylvester matrix equations‎. ‎in this paper‎, ‎we‎ ‎study these algorithms in the case that the coefficient matrices‎ ‎are real symmetric (real symmetric positive definite) and extract‎ ‎two cg-type algorithms for solving generalized sylvester matrix‎ ‎equations‎. ‎the proposed methods are iterative projection metho...

Introduction: Measuring and managing risk has been of greater concern to investors and fund managers especially after the financial crisis 2007. Many mathematical and statistical methods have been developed and improved to aim at providing a more accurate and better control over risk and efficient asset allocation. While financial professionals refer to risk as standard deviation of securities,...

 Background: A cross-sectional analytic method was used to assess health and safety risks that really matter in restaurants of universities and hospitals in the Gaza strip, Palestine.  Materials and methods: A 40-item questionnaire was completed by workers in all university and governmental hospital restaurants in the Gaza strip. Another 30-item questionnaire was completed by unive...

let and be a sequence with non-negative entries. if , denote by the infimum of those satisfying the following inequality: whenever . the purpose of this paper is to give an upper bound for the norm of operator t on weighted sequence spaces d(w,p) and lp(w) and also e(w,?). we considered this problem for certain matrix operators such as norlund, weighted mean, ceasaro and copson matrices. th...