Privatisation of public enterprises in Turkey: the case of PETKİM

Ankara : The Department of Management and the Graduate School of Business Administration of Bilkent Univ., 1990.Thesis (Master's) -- Bilkent University, 1990.Includes bibliographical references leaves 31-32.This research analyzes the concept of privatisation of Turkish state economic enterprises (SEE’s) throiçh the specific case of PETKIM, a public petrochemical monopoly. It consists of four parts. In the first part. a<Iescription of public enterprises is given. The extent of the public sector in the -world, the origins of industrialisation by SEE’s in developing countries are discussed. This part ends with the description of the common problems of SEE’s such as insufficient financial performance or inefficient management. The second part starts with the definition of privatisation. Then, the objectives of privatisation in Turkey and its implementation are described. The third part of this research tries to investigate the problems that PETKIM faces at the stage of privatisation. The lack of economies of scale and outdated technology of some of its plants are the major ones. Then, several methods of privatisation for PETKIM are evaluated. In the lost part, the Implications of privatisation are analyzed and in each case some recommendations are made. The mein issues are the use of the proceeds from privatisation and the impacts of privatisation on productive, allocative and managerial efficienciesÖzbay, Mehmet SM.S

Stable H∞ controller design for time-delay systems

This paper investigates stable suboptimal [image omitted] controllers for a class of single-input single-output time-delay systems. For a given plant and weighting functions, the optimal controller minimizing the mixed sensitivity (and the central suboptimal controller) may be unstable with finitely or infinitely many poles in +. For each of these cases, search algorithms are proposed to find stable suboptimal [image omitted] controllers. These design methods are illustrated with examples

Design of a switched robust control scheme for drug delivery in blood pressure regulation

A control algorithm based on switching robust controllers is presented for a Linear Parameter Varying (LPV) time-delay system modeling automatic infusion of vasodilator drug to regulate postsurgical hypertension. The system is scheduled along a measurable signal trajectory. The prospective controllers are robustly designed at various operating points forming a finite set of robust controllers and then a hysteresis switching is performed between neighboring robust controllers for a larger operating range of the LPV system. The stability of the switching LPV system for the entire operating range is ensured by providing a sufficient condition in terms of bound on the scheduling signal variation using the concept of dwell time. Simulation results are provided to verify the performance of the designed control scheme. © 201

Sensitivity minimization by strongly stabilizing controllers for a class of unstable time-delay systems

Weighted sensitivity minimization is studied within the framework of strongly stabilizing (stable) Hinfin controller design for a class of infinite dimensional systems. This problem has been solved by Ganesh and Pearson, for finite dimensional plants using Nevanlinna-Pick interpolation. We extend their technique to a class of unstable time delay systems. Moreover, we illustrate suboptimal solutions, and their robust implementation. © 2009 IEEE

Sensitivity minimization by stable controllers for a class of unstable time-delay systems

In this paper sensitivity minimization problem is considered for a class of unstable time delay systems. Our goal is to find a stable controller stabilizing the feedback system and giving rise to smallest H∞ norm for the sensitivity function. This problem has been solved by Ganesh and Pearson (1986) for finite dimensional plants using Nevanlinna-Pick interpolation. We extend their technique to include possibly unstable time delay systems. Moreover, we illustrate suboptimal solutions, and their robust implementation. © 2006 IEEE

Remarks on H ∞ controller design for SISO plants with time delays

The skew Toeplitz approach is one of the well developed methods to design H ∞ controllers for infinite dimensional systems. In order to be able to use this method the plant needs to be factorized in some special manner. This paper investigates the largest class of SISO time delay systems for which the special factorizations required by the skew Toeplitz approach can be done. Reliable implementation of the optimal controller is also discussed. It is shown that the finite impulse response (FIR) block structure appears in these controllers not only for plants with I/O delays, but also for general time-delay plants

Sensitivity minimization by stable controllers: An interpolation approach for suboptimal solutions

Weighted sensitivity minimization is studied within the framework of strongly stabilizing (stable)H∞controller design for a class of infinite dimensional systems. This problem has been solved by Ganesh and Pearson, [8], for finite dimensional plants using Nevanlinna-Pick interpolation. We extend their technique to a class of unstable time delay systems. Moreover, we illustrate suboptimal solutions, and their robust implementation. © 2007 IEEE

On the mixed sensitivity minimization for systems with infinitely many unstable modes

In this note we consider a class of linear time invariant systems with infinitely many unstable modes. By using the parameterization of all stabilizing controllers and a data transformation, we show that ℋ ∞ controllers for such systems can be computed using the techniques developed earlier for infinite dimensional plants with finitely many unstable modes. © 2004 Elsevier B.V. All rights reserved

H∞ filter design for vehicle tracking under delayed and noisy measurements

In many intelligent vehicles applications tracking plays an important role. This paper considers tracking of a vehicle under delayed and noisy measurements. For this purpose we design an H∞ optimal filter for linear systems with time delays in the state and output variables. By using the duality between filtering and control, the problem at hand is transformed to a robust controller design for systems with time delays. The skew Toeplitz method developed earlier for the robust control of infinite dimensional systems is used to solve the H∞ filtering problem. The results are illustrated with simulations and effects of the time delay on the tracking performance are demonstrated. ©2007 IEEE

Distribution of mast cells in lung tissues of rats exposed to biomass smoke

This study was designed to evaluate the distribution of mast cells in the lung tissues of rats exposed to biomass  smoke. Fifty six female Wistar albino adult rats were used. They were divided into two experimental groups  (control and biomass smoke-treated), each containing 28 animals. Control rats were not exposed to the  biomass smoke at any time during the experiment. Rats in the treatment group were exposed daily (one hour)  to biomass smoke for 3, 6 or 9 months. Lung tissues samples were obtained under deep anesthesia from the  randomly selected 7 animals in both groups. Lung tissues were fixed in Mota’s fixative (BLA) for 24 h and  embedded in paraffin. Sections of 6 μm thickness were cut and stained with 0.5% toluidine blue in 0.5 N  hydrochloric acid at pH 0.5 for 30 min. The numbers of mast cell in lung tissues of the animals exposed to  the biomass for 6 or 9 months were significantly (P&lt;0.05) higher than controls. This study showed that long  term exposure to biomass smoke was associated with the increased number of mast cells in the lung.