Grounded capacitor-based new floating inductor simulators and a stability test

In this paper, two new floating inductor simulators (FISs), both using two differential difference current conveyors, are considered. The proposed FISs do not suffer from passive component matching constraints and employ a minimum number of passive elements. They use a grounded capacitor; accordingly, they are suitable for integrated circuit technology. They have good low- and high-frequency performances. Simulations are performed with the SPICE program to verify the claimed theory. Moreover, for the first FIS used in a second-order low-pass filter, a stability test is performed as an example. © TÜBITAK

Using 2-Opt based evolution strategy for travelling salesman problem

Harmony search algorithm that matches the (µ+ 1) evolution strategy, is a heuristic method simulated by the process of music improvisation. In this paper, a harmony search algorithm is directly used for the travelling salesman problem. Instead of conventional selection operators such as roulette wheel, the transformation of real number values of harmony search algorithm to order index of vertex representation and improvement of solutions are obtained by using the 2-Opt local search algorithm. Then, the obtained algorithm is tested on two different parameter groups of TSPLIB. The proposed method is compared with classical 2-Opt which randomly started at each step and best known solutions of test instances from TSPLIB. It is seen that the proposed algorithm offers valuable solutions

Using 2-Opt based evolution strategy for travelling salesman problem

Harmony search algorithm that matches the (µ+1) evolution strategy, is a heuristic method simulated by the process of music improvisation. In this paper, a harmony search algorithm is directly used for the travelling salesman problem. Instead of conventional selection operators such as roulette wheel, the transformation of real number values of harmony search algorithm to order index of vertex representation and improvement of solutions are obtained by using the 2-Opt local search algorithm. Then, the obtained algorithm is tested on two different parameter groups of TSPLIB. The proposed method is compared with classical 2-Opt which randomly started at each step and best known solutions of test instances from TSPLIB. It is seen that the proposed algorithm offers valuable solutions

A new wideband electronically tunable grounded resistor employing only three MOS transistors

In this paper, a new wideband electronically tunable grounded resistor, namely a grounded voltage controlled resistor (GVCR) including only three MOS transistors, is suggested. The proposed GVCR, without requiring any additional bias currents and voltages, has only one control voltage. Linearity analysis for the proposed GVCR is given. A new second-order multifunctional filter using two differential voltage current conveyors is also included as an application example. Some postlayout simulation results with SPICE are included to show the performance, workability, and effectiveness. © 2016 Tübitak

Coordinate transformation based time-varying linear sliding surface

Bu çalışmanın amacı, kayma yüzeyi tasarımı için yeni bir yöntem geliştirmektir. Yeni yaklaşımlar; birisi kayma yüzeyinin kendisi, diğeri ise doğal olarak kayma yüzeyine dik olan bir koordinat ekseninde geliştirilmiştir. Daha sonra, kontrol kuralı Lyapunov kararlılık koşulu uygulanarak düzenlenmiştir. Önerilen yeni kayma yüzeyi bulanık mantık kontrol, yakın komşuluk ve fonksiyon atama yaklaşımları kullanılarak zamanla değişen bir parametre yardımı ile ayarlanmıştır. Elde edilen yöntemlerin analizi parametre belirsizlikleri ile sınır değerli dış bozuculara sahip ikinci derece sistem modeli üzerinde koşturulan benzetimlerle yapılmıştır. Çeşitli başarım ölçütleri kullanılarak önerilen yöntemin ulaşma zamanının azaltılmasının, bozuculara karşı dayanıklılık, yumuşak faz düzlemi yörünge hareketi gibi olumlu iyileştirmeler sağladığı gözlenmiştir.Anahtar Kelimeler: Kayma kipli kontrol, kayma yüzeyi tasarımı.The aim of this study is to propose new approaches for on-line tuning of the linear sliding surface in the sliding mode controllers. The new approaches are developed for a class of second order systems on a new coordinate axes that one of which is the classical sliding surface and the other one is naturally chosen to be orthogonal to it. The control law is then modified accordingly by applying the Lyapunov stability condition. The adjustment of the linear sliding surface defined in the new coordinate axes is achieved by tuning a new parameter using three different methods. First, an adaptive sliding surface with a rotation scheme is constructed by interpreting the classical delta neighborhood approach. Next, the rotation process is achieved by using a fuzzy tuning mechanism that uses the new coordinates as its input variables and generates an incremental change in the new parameter value as an output. Thirdly, a time-varying function is used for defining the new parameter. Numerical simulations are performed on a second order system model with parameter uncertainties and bounded external disturbance. The new approaches are compared with the sliding mode controller having a constant sliding surface and two sliding mode controllers having a continuously time-varying sliding surface. Results have shown improved performances of the proposed approaches in terms of a decrease in the reaching and settling times, robustness to disturbances and smooth phase plane trajectory.Keywords: Sliding mode control, sliding surface design

Sliding mode controlled bioreactor using a time-varying sliding surface

Bioreactor processes based on substrate concentration have both highly non-linear behaviour and parameter uncertainties mostly bounded with physical and biological constraints, which make them a subject area of sliding mode control. This work deals with sliding mode control of a fermentation process in a continuous stirred bioreactor. A new sliding surface is defined using angular information as a function of time that provides adjustable continuous movement of the sliding surface. Computer simulations are presented to show the effectiveness and efficiency of the proposed method and to make a quantitative comparison with the conventional sliding mode controller having a constant sliding surface. The excess amount of substrate concentration in the mixture causes undesired by-product information. Therefore, the substrate concentration should not stay above its desired value for a long time. It is shown in the simulations that the performance of the proposed method, especially in regard to the settling time of the substrate concentration and reaching time, is improved. It is also shown that different system state trajectories could be obtained with the proposed method by adjusting the defined parameters of the angular information. © 2009, The Institute of Measurement and Control. All rights reserved

Coordinate Transformation Based Time-varying Sliding Surface Design Methods

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2003Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2003Bu çalışmanın ana amacı, kayma kipli kontrolörlerde kayma yüzeyinin gerçek zamanlı ayarlanması için yeni yaklaşımlar önermektir. Yeni yaklaşımlar, biri geleneksel kayma yüzeyi diğeri ise doğal olarak buna dik olarak seçilen yeni eksen koordinatlarında bir sınıf ikinci derece sistem için oluşturulmuştur. Daha sonra bu yeni yapıya göre, kayma kipli kontrol kuralına ait kontrol işareti Lyapunov kararlılık koşulu uygulanarak düzenlenmiştir. Yeni koordinat ekseninde tanımlanan kayma yüzeyleri doğrusal ve doğrusal olmayan yapılarda elde edilmiştir. Doğrusal kayma yüzeyi için öncelikle, geleneksel delta komşuluk yaklaşımı yorumlanarak dönme düzenine sahip uyarlamalı bir kayma yüzeyi oluşturulmuştur. İkinci olarak, dönme işlemi giriş değişkenleri olarak yeni koordinat eksenini kullanan ve çıkış olarak yeni parametre değerinin değişimini üreten bulanık bir ayarlama mekanizması kullanılarak gerçeklenmiştir. Son olarak ise aynı koordinat ekseninde tanımlanmış bir fonksiyon kullanan bir mekanizma tanıtılmıştır. Doğrusal olmayan durumda, ayarlama mekanizması için bir fonksiyon tanımlanmıştır. Sayısal benzetimler sınırlı dış bozuculara ve parametre belirsizliklerine sahip ikinci derece doğrusal olmayan sistem modelleri üzerinde koşturulmuştur. Yeni yaklaşımlar literatürde bulunan bazı kayma yüzeyi tasarım yöntemleri ile ve sabit kayma yüzeyine sahip geleneksel kayma kipli kontrolör ile karşılaştırılmıştır. Sonuçlar, önerilen yaklaşımların ulaşma ve yerleşme zamanı ile bozuculara olan gürbüzlük açısından geleneksel kayma kipli kontrolöre göre başarım artışını göstermektedir.The main objective of this study is to propose new approaches for on-line tuning of the sliding surface slope in sliding mode controllers. The new approaches are developed for a class of second order systems on a new coordinate axes that one of which is the classical sliding surface and the other one is naturally chosen to be orthogonal to it. The control input of the sliding mode control law is then modified accordingly by applying the Lyapunov stability condition. The sliding surface defined in the new coordinate axes is obtained in linear and nonliear structures. For the linear sliding surface, first, an adaptive sliding surface with a rotation scheme is constructed by interpreting the classical delta neighbourhood approach. Secondly, the rotation process is achieved by using a fuzzy tuning mechanism that uses the new coordinates as its input variables and generates an incremental change in the new parameter value as an output. At last, a rotation mechanism that uses a function defined on the same new coordinate axes is presented. For the nonlinear case, a function is defined for the adjustment mechanism. Numerical simulations are performed on second order nonlinear system models with parameter uncertainties and bounded external disturbance. The new approaches are compared with sliding surface design methods from the literature and also with the classical sliding mode controller having a constant sliding surface. Results have shown improved performances of the proposed approaches in terms of a decrease in the reaching and settling times, robustness to disturbances as compared with classical sliding mode controller.DoktoraPh