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

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

A new method for generating initial solutions of capacitated vehicle routing problems

In vehicle routing problems, the initial solutions of the routes are important for improving the quality and solution time of the algorithm. For a better route construction algorithm, the obtained initial solutions must be basic, fast, and flexible with reasonable accuracy. In this study, initial solutions improvement for CVRP is introduced based on a method that is introduced in the literature. Using a different formula for addressing the gravitational forces, a new method is introduced and compared with the previous physics inspired algorithm. By using the initial solutions of the proposed method and using them as RTR and SA initial routes, it is seen that better results are obtained when compared with various algorithms from the literature. Also, in order to fairly compare the algorithms executed on different machines, a new comparison scale for the solution quality of vehicle routing problems is proposed that depends on the solution time and the deviation from the best known solution. The obtained initial solutions are then input to Record-to-Record and Simulated Annealing algorithms to obtain final solutions. Various test instances and CVRP solutions from the literature are used for comparison. The comparisons with the proposed method have shown promising results

Physics-inspired optimization algorithm for obtaining initial routes of capacitated vehicle routing problem

Capacitated vehicle routing problem (CVRP) is NP-Hard and computing exact solutions in real life situations is mostly infeasible. Therefore, heuristic methods are used as an alternative. In heuristic methods the quality of the final solution is directly related with the initial solution space. In this study, artificial physics based optimization algorithm is applied to CVRP in order to obtain the initial population pool of a heuristic method. The A, B and P group 74 test instances of Augerat et al are considered. The group average deviations of the initial solutions from best known solutions is calculated as 37.95%, 32.10% and 31.45% for A, B and P groups respectively. Then, a conventional genetic algorithm (GA) with one point crossover and one point mutation is chosen as a heuristic search algorithm and the initial solutions obtained are used for the first generation of the GA. The GA is executed 1000 generations with crossover and mutation rates as 0.9 and 0.1, respectively. For each problem, GA is executed 10 times and best output is recorded. As a result, 7.15%, 4.37% and 6.33% group average deviations are obtained after heuristic search

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

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

Sliding mode control of a coupled tank system with a state varying sliding surface parameter

In general, sliding mode controllers with moving sliding surfaces are achieved by using time-dependent expressions. In this situation, the parameters of the sliding surface have to be rearranged if the initial conditions of the error phase plane are changed. This paper presents a special purpose approach with a state dependent moving algorithm for the control of the coupled tank system where the state variables are defined as the liquid levels of the tanks. Instead of using a time-dependent parameter, sliding surface parameter is adjusted by directly using the state variables of the tank system. The comparisons with a conventional sliding mode controller for different desired liquid levels are presented via simulations. The simulation results show that sliding mode controller with a state varying sliding surface parameter has a better performance with respect to conventional sliding mode controller even when the system initial conditions of the error phase plane are varied. ©2008 IEEE

Using polynomial functions for a time varying sliding surface with angular information

Sliding surface translation that has been defined using angular information as a linear function of time provides an equally spaced rotation of the sliding surface and a smoother control under predefined error state constraints. In this study, second order single-input non-autonomous dynamic open-loop systems will be considered and a higher order polynomial will be used to define the time-varying structure of the angular information. Then, it will be shown via simulations that different phase plane trajectories could be obtained with the proposed method. For the simulations, the trajectory tracking problem will be considered. Then, the same phase plane characteristics obtained using a continuously time-varying linear sliding surface design method selected from the literature will be directly obtained by assigning the polynomial coefficients of the angular sliding surface. © 2015 IEEE

Statistical and computational intelligence tools for the analyses of warp tension in different back-rest oscillations

In this paper, experimental, computational intelligence based and statistical investigations of warp tensions in different back-rest oscillations are presented. Firstly, in the experimental stage, springs having different stiffnesses are used to obtain different back-rest oscillations. For each spring, fabrics are woven in different weft densities and the warp tensions are measured and saved during weaving process. Secondly, in the statistical investigation, the experimental data are analyzed by using linear multiple and quadratic multiple-regression models. Later, in the computational intelligence based investigation, the data obtained from the experimental study are analyzed by using artificial neural networks that are universal approximators which provide a massively parallel processing and decentralized computing. Specialty, radial basis function neural network structure is chosen. In this structure, cross-validation technique is used in order to determine the number of radial basis functions. Finally, the results of regression analysis, the computational intelligence based analysis and experimental measurements are compared by using the coefficient of determination. From the results, it is shown that the computational intelligence based analysis indicates a better agreement with the experimental measurement than the statistical analysis