Current Issue : July - September Volume : 2012 Issue Number : 3 Articles : 5 Articles
Turkish Sugar Inc., a public enterprise including 25 factories, is the first corporation of Turkish\r\nindustry. According to the government policy, public sugar factories PSFs will be privatized\r\nas geography-based 6 portfolio groups in two years. As performance measures of PSF affect\r\ngovernment, sugar producers, and several unions in privatizing process, a systematic approach\r\nis necessary to measure efficiencies and grouping factories. This paper uses a new DEA- Data\r\nEnvelopment Analysis- based clustering approach for measuring efficiency scores of PSF and\r\ngrouping them instead of geography- based portfolio groups. This new approach can help decision\r\nmakers in privatizing process. At the same time, target values obtained by dual model can be used\r\nto eliminate inefficiencies of some PSFs....
We extend the application of Legendre-Galerkin algorithms for sixth-order elliptic problems with\r\nconstant coefficients to sixth-order elliptic equations with variable polynomial coefficients. The\r\ncomplexities of the algorithm are O(N) operations for a one-dimensional domain with N - 5\r\nunknowns. An efficient and accurate direct solution for algorithms based on the Legendre-\r\nGalerkin approximations developed for the two-dimensional sixth-order elliptic equations with\r\nvariable coefficients relies upon a tensor product process. The proposed Legendre-Galerkin\r\nmethod for solving variable coefficients problem is more efficient than pseudospectral method.\r\nNumerical examples are considered aiming to demonstrate the validity and applicability of the\r\nproposed techniques....
A fractional-order control strategy for pneumatic position servosystem is presented in this paper.\r\nThe idea of the fractional calculus application to control theory was introduced in many works, and\r\nits advantages were proved. However, the realization of fractional-order controllers for pneumatic\r\nposition servosystems has not been investigated. Based on the relationship between the pressure\r\nin cylinder and the rate of mass flow into the cylinder, the dynamic model of pneumatic position\r\nservo system is established. The fractional-order controller for pneumatic position servo and\r\nits implementation in industrial computer is designed. The experiments with fractional-order\r\ncontroller are carried out under various conditions, which include sine position signal with\r\ndifferent frequency and amplitude, step position signal, and variety inertial load. The results show\r\nthe effectiveness of the proposed scheme and verify their fine control performance for pneumatic\r\nposition servo system....
Nowadays bootstrap techniques are used for data analysis in many other fields like engineering,\r\nphysics, meteorology, medicine, biology, and chemistry. In this paper, the robustness ofWu 1986\r\nand Liu 1988�s Wild Bootstrap techniques is examined. The empirical evidences indicate that\r\nthese techniques yield efficient estimates in the presence of heteroscedasticity problem. However,\r\nin the presence of outliers, these estimates are no longer efficient. To remedy this problem, we\r\npropose a Robust Wild Bootstrap for stabilizing the variance of the regression estimates where\r\nheteroscedasticity and outliers occur at the same time. The proposed method is based on the\r\nweighted residuals which incorporate the MM estimator, robust location and scale, and the\r\nbootstrap sampling scheme of Wu 1986 and Liu 1988. The results of this study show that the\r\nproposed method outperforms the existing ones in every respect....
The aim of this paper is to introduce two approaches to near sets by using a special neighbourhood.\r\nSome fundamental properties and characterizations are given. We obtain a comparison between\r\nthese new set approximations as well as set approximations introduced by Peters 2011, 2009, 2007, 2006....
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