Showing papers in "Mathematical & Computational Applications in 2003"

Boolean Functions Simplification Algorithm of O(n) Complexity

Abstract: The minimization of Boolean functions allows designers to make use of fewer components, thus reducing the cost of particular system. All procedures for reducing either two-level or multilevel Boolean networks into prime and irredundant form have O(2n) complexity. Prime Implicants identification step can be computational impractical as n increases. Thus it is possible to get method in order to find the minimal set of Prime Implicants of O(n) complexity instead of O(2n).

Sliding Mode Speed Control for DC Drive Systems

Abstract: In this study, the Sliding Mode Control theory of the Variable Structure System has been applied to the speed control of a de motor. The dynamic performance of the sliding mode speed control system has been studied against system parameter variations and external load disturbance and the simulation results are given. The application of the sliding mode control theory to controller design for DC drive control system shows a robust system performance.

A Dynamic Load Balancing Model for a Distributed System

Abstract: A communication protocol designed for fault tolerance in distributed real time systems is implemented and a dynamic load balancing model is designed and implemented over this protocol. The protocol consists of cluster based, hierarchical rings which use synchronous communication. The rings are synchronous. At the lowest level in the hierarchy, there are clusters that consist of computing processors, called nodes. The higher level consists of the cluster representatives that manage the clusters of the lower level. There can be two or more levels in the hierarchy. Ring protocols in each cluster can work in parallel. Also, a fault tolerance mechanism is integrated to the protocol. The dynamic distributed load balancing module designed over the protocol aims to maximize the overall performance of the whole system by distributing the load submitted to the system efficiently and transparently among the nodes. While performing operations to achieve this goal, the module also considers the real-time constraints of the system

A Neural Network Image Recognition for Control of Manufacturing Plant

Abstract: The aim of this work is to interpret the image for vision-based logic control of manufacturing plant. The images. which had been taken by an overhead fixed camera, were transformed with feature value by image preprocessing. A multi-layered neural network was used to recognize randomly selected images of metallic pegs and plastic rings. Images, which are not recognized by the neural network, will be rejected and consequently the actuator will allow the objects to pass through. On the other hand, if the images are recognized by the neural network then the logic controller generates different type of action and the actuator pushes the object down.

A Windows-Based Digital Filter Design

Abstract: This study aims to describe a general digital filter, practically for Windows’ users. For this purpose. an I/O interfacing circuits base on PIC16F877 was designed to receive analog signal into the PC and return filtered signals. This I/O module was then communicated with PC using parallel port protocol with EPP mode, and a digital filter program was introduced using C++. Various filters; such as LPF, HPF, BPF, and BSF were designed using the method of frequency transformation on normalized Butterworth and Chebyshev analog filters. The grades of the designed filters range from n=1 to n=8. Using this application the proposed windows-based digital filter design worked better and faster.

Cutting Tool Condition Monitoring Using Surface Texture via Neural Network

Abstract: For defining surface finish and monitoring tool wear is essential for optimisation of machining parameters and performing automated manufacturing systems. There is very close relationship between tool wear and surface finish parameters as surface roughness (Ra,) and maximum depth of profile (Rt). The machined surface reflects the rate of tool wear and the plot of surface pmvides reliable information about tool condition. In this paper an approach for estimating Ra,and Rt in milling process using the artificial neural networks is proposed. Feed-forward multi-layered neural networks, trained by the back-propagation algorithm are used. In training phase seven input parameters (v, f, d, Fx, Fy, Fz and Vb) and two output parameters are used and the network architecture is as 7x6x6x6x2. It was found that the ANN results are very close to the experimental resuks. The developed model can be used to define the quality of surface finish in tool condition monitoring systems.

A Different Method Determining Dielectric Constant of Soil and Its FDTD Simulation

Abstract: In this study, a different method determining the dielectric constant of soil via probes is presented. The method is based on the principle of measuring pulse delay in a given matter. The experimental study, which was carried out basically using an HP8753A vector network analyser, was repeated for various soil mixtures having different values of wetness. The results obtained from the measurements have clearly shown that the dielectric constant of the soil was increasing almost proportionally with that of the moisture content in the soil. The suitability of the measuring method was also checked with a number of simulation results obtained directly using the finite difference time domain method (FDTD).

Invariant Solutions and Conservation Laws of the Black-Scholes Equation

Abstract: As the Black-Scholes equation can be transformed into the one-dimensional linear heat equation via two sets of transformations, an optimal system of one-dimensional subalgebras for the one-dimensional heat equation is exploited to obtain two classes of optimal systems of one-dimensional subalgebras for the well-known Black-Scholes equation of the mathematics of finance. Two methods for the derivation of the two classes of optimal systems of group-invariant solutions for this model are available. We present the simpler approach

Determination of Complex Dielectric Permittivity of Loss Materials at Microwave Frequencies

Abstract: The method of determination of complex dielectric permIttIvIty of loss materials at microwave frequencies (X-band) using measured amplitudes of reflection and transmission coefficients and numerical calculations is developed. Different numerical methods namely graphical, bisection (halving), newton, and secant, are applied in order to determine the permittivity of cement-based materials. Simulation time and errors of these methods are compared. It is shown that the fastest and most accurate method is the bisection (halving) method because it is a global method.

Potential Symmetry Generators of Some Perturbed Nonlinear Evolution Related Equations

Abstract: Some recent results on approximate Lie group methods and previously developed concepts on potential symmetries are extended and applied to nonlinear systems perturbed to some order by a small parameter. The potential (or auxiliary) form of the perturbed . system necessarily requires knowledge of an "approximate" conservation law of the system. We make an analysis on a perturbed Burgers equation and discuss other nonlinear equations where the results are applicable.

Vibrations of a Simply Supported Beam with a Non–Ideal Support at an Intermediate Point

Abstract: A simply supported Euler-Bernoulli beam with an intermediate support is considered. The concept of non-ideal boundary conditions is applied to the beam problem. In accordance, the intermediate support is assumed to allow small deflections. Approximate analytical solution of the problem is found using the Method of Multiple Scales, a perturbation techniques. Ideal and non-ideal frequency response curves are contrasted.

A Comparison on the Commutative Neutrix Products of Distributions

Abstract: In this work, we define a new commutative neutrix product of distribution and than we make a comparison with present commutative product of distributions by providing a counterexample that two commutative neutrix products of the distributions differ.

On Some Sequence Spaces and Lacunary σ-Statistical Convergence

Abstract: In this note, we define and study two concepts which arise from the notion of lacunary strong convergence, and invariant means, namely lacunary strong σ- convergence with respect to an Orlizi function and lacunary a-statistical convergence and established the relationship between these two concepts.

Fuzzy Inference System Based on Neural Network for Technological Process Control

Abstract: The implementation of a fuzzy system for technological process control based on parallel architecture and learning capabilities of neural networks is considered. The algorithms of fuzzy inference system on neural network (neuro-fuzzy system) are described. To train unknown coefficients of the system, the supervised learning algorithm is used. As a result of learning, the rules of neuro-fuzzy system are generated. The neuro-fuzzy system is applied to control a dynamic plant. Using desired time response characteristics of the system the synthesis of neuro-fuzzy controller for technological process control is carried out. The simulation result of the neuro-fuzzy control system is compared with the simulation results of control systems based on PID- and neural controller. It is found that the neuro-fuzzy control system has better control performance than the others.

Prediction of Ratio of Mineral Substitution in the Production of Low-Clinker Factored Cement by Artificial Neural Network

Abstract: Artificial Neural Networks (ANN) has been widely used to solve some of the problems in science and engineering, which requires experimental analysis. Use of ANN in civil engineering applications started in late eighties. One of the important features of the ANN is its ability to learn from experience and examples and then to adapt with changing situations. Engineers often deal with incomplete and noisy data, which is one of the areas where ANN can easily be applied. Dealing with incomplete and noisy data is the conceptual stage of the design process. This paper shows practical guidelines for designing ANN for civil engineering applications. ANN is in cement industry: in the production of low-clinker factored cement, and in the derivation of composition of natural and artificial puzzolans in the production of high performance cement and concrete. By using ANN, a study to find out the optimum ratio of substitution and compression strengths was carried out.

The Resonance Analysis Caused by Harmonics in Power Systems Including Thyristor Controlled Reactor

Abstract: The static VAR compensators having fixed capacitor thyristor controlled reactor (FC-TCR) used to improve voltage stability in power systems are nonlinear elements. The fixed capacitor group will produce reactive power while the thyristor controlled reactor will consume reactive power in compensators having FC-TCR. Changing the firing angles of TCR provides the reactive power variation of the system since the reactive power production of capacitors is fixed at a determined voltage level. In some cases, the variation of these firing angles will cause the harmonics in the system. In this study, TCR's are discussed to be harmonic sources and the resonance case caused by harmonics has been investigated with Fourier Matrix Model and MATLAB Software.

On the Buckling Analysis of Plates Reinforced with Stiff Ribs

Abstract: This paper deals with analytical buckling analysis of the rectangular orthotropic simply supported plates reinforced with longitudinal stiff ribs. It was considered that the ribs with rectangular and circular cross-sections were parallel and equivalent to each other. It was further assumed that the ribs were rigidly fastened to the plate and that their cross sections were perpendicular to the undeformed middle surface of the plate. These reinforced plates were subjected to the uniaxial uniform distributed compressive loads. In the study, the effect of the numbers and the cross-sections of the ribs on the buckling load were investigated. The results are striking in that how the ribs effect the isotropic plates with low strength.

The Monitoring Simulation of a Lathe

Abstract: The study of machine-tool dynamic is realised here as “monitoring”, meaning checking and improving the functioning of the machine. The state of processing is followed with certain sensors which signs are processed inside the computer, then it takes the decision of monitoring, meaning the identification of a class from the set of classes (process conditions). For monitoring in turning, it is shown the classes (tool conditions). The vibrograms that represent: - the components variations of the cutting force; - the relative displacement between tool and piece, on the repelling direction; - the power furnished by the electric engine, are realised with the functions RANDN and RAND (from MATLAB). Based on them it is calculating 11 monitoring indices. The class resulted at the experiment (simulate) i, which corresponds to the monitoring indices, we establish with the function REM. The ANN with 11 inputs (the number of monitoring indices) and 8 outputs (the number of classes) is realised with 3 layers. The network is made with the function newff, trained with the function train and simulated with the function sim.

Adaptive GIS Image Compression and Restoration Using Neural Networks

Abstract: This study aims to describe research into the field of GIS image compression, decompression and restoration. Geographical Information System (GIS) data comprises huge size into memory. For this purpose, it needs compression, which has high compression rate. But high compression rate cause of some distortion and losses. Restoration is a process by which an image suffering some form of distortion or degradation can be recovered to its original form. The proposed windows-based image compression and restoration was implemented using Delphi.

Application of FFT and Arma Spectral Analysis to Arterial Doppler Signals

Abstract: In this study, Doppler signals recorded from arteries of 105 subjects were processed by PC-computer using fast Fourier transform, and least squares modified Yule-Walker autoregressive moving average methods. By using these spectrum analysis techniques, the variations in the shape of the Doppler spectrums as a function of time were presented in the form of sonograms in order to obtain medical information. These sonograms were then used to compare the applied methods in terms of their frequency resolution and the effects in determination of stenosis and occlusion in arteries. Reliable information on hemodynamic alterations in arteries can be obtained by evaluation of these sonograms.

Evaluation of Control Methods on a Structural System

Abstract: In this study, PID, LQR and sliding mode controllers are designed as active seismic isolation devices on a multi degrees of freedom structure. At first PID control is applied as a conventional method. Since this control method can be applied easily and well known widely, it has an important role in control applications. Secondly, a LQR is designed to suppress the vibrations of the structural system. But these methods are not insensitive to parameter changes. Since the model might have uncertainties and/or parameter changes. sliding mode control has been introduced because of its well-known robust character and superior performance. Additionally, this control method can easily be applied to non-linear systems. The simulated system has four stories. A disturbance input representing earthquake is applied to the base. At the end of the study, the Lime history of the storey displacements, control voltage and frequency responsc of the both uncontrolled, PID, LQR and sliding mode controlled structures have been presented and results have been compared.

Goursat Problem for the Factorizable Hyperbolic Equation in Two Independent Variables

Abstract: For the scalar linear hyperbolic partial differential equations (PDEs) in two independent variables to be factorizable, the Laplace invariants h or k must be zero. In this paper, we find the Riemann function for the Goursat problem using the Lie group theoretical method where the hyperbolic . equation involved is factorized. What emerges is that the ordinary differential equation (ODE) whose solution gives the Riemann function for the Goursat problem is factorizable. Finally, an example is given as application of the methods

Stress Intensity Factors for a Ring-Shaped Crack in a Transversely Isotropic Thick Layer

Abstract: The problem of a ring-shaped crack in an infinitely long thick layer was considered in this study. The problem was formulated for a transversely isotropic material by using integral transform technique under uniform load. Due to the geometry of the configuration, Hankel integral transform technique was chosen and the problem was reduced to a singular integral equation. This integral equation was solved numerically by using Gaussian Quadrature Formulae and the values were evaluated for discrete points. Stress intensity factors were obtained by using these values. They were tabulated for various ring−haped crack sizes and transversely isotropic materials.

Modelling Tractive Performance for Drive Wheel

Abstract: A model was developed by regression analysis to predict the tractive performance of 700-18 radial ply tire for agricultural tractors Different parameters that affect the cone index of soil and wheel slip were considered for the analysis To obtain experiments values belonging to tractive performance of tire, a study was conducted in the soil bin by using a single wheel agricultural tire test machine Performance of this model was compared with model developed by Wismer and Luth (1974) to predicted tractive performance Mathematical and statistical methods were used to fitting and analysing of models Results showed that M1 model outputs were closer to experimental values than M2 model outputs for prediction of traction performance

On Complexity of a Global Optimization Problem

Abstract: The Solution of the Subproblem of the Cutting Angle Method of Global Optimization for problems of minimizing increasing Positively Homogeneous of degree one functions is proved to be NP-Complete. For the proof of this fact we formulate another problem which we call "Dominating Subset with Minimal Weight". The solution of this problem is also NP-Complete.

Prediction of Magnetic Properties of Strip Wound Toroidal Cores up to 2 Khz Using Artificial Neural Network

Abstract: Although magnetic wound cores have simple geometries, their magnetic properties vary in a complex manner depending on core geometry and dimensions etc. These parameters have a strong influence on magnetic performance of wound toroidal cores made from electrical steels or similar strip products. Through theoretical evaluation and experimental measurements carried out over a few years, magnetic performance of a range of strip wound cores have been quantified at low and high frequency. Using this information a neural network model has been developed for prediction core magnetic field strength, power loss and permeability a wide range of flux density and frequency. Input parameters include variables such as core geometry; dimensions strip width and thickness, induction frequency and flux density. The developed network provides flexibility in the choice of training parameters. transfer functions and training algorithm thereby enhancing accuracy.

Recovering Images from Traveltime Data

Abstract: We study here a mathematical problem of retrieving slowness (reciprocal of velocity) distribution of a medium from a set of the measured first arrivals traveltimes data between source?sand receivers within the medium.

Asymptotic Evaluation of the Edge Diffraction in Cylindric Paraboloidal Reflector Antennas

Abstract: Diffraction fields on the edge of a cylindrical parabolic reflector antenna are examined. Firstly canonical problem is defined for the edge of the antenna and study is reduced to a half plane scattering problem. Coordinate system is defined as the origin being the edge of the reflector, so the feed became offset. Space is divided into two parts according to p and edge diffracted fields are calculated for the region where ρ ≤ ρ0. Obtained poorly divergent series are changed into complex integrals for k→∞ and these integrals are solved in the same conditions. Uniform expression of edge diffracted field is calculated by using Fresnel integrals.

Neural Network Using Genetic Algorithm for Magnetic Performance Prediction of Toroidal Wound Cores at 50 Hz

Abstract: Geometrical and building parameters have a strong influence on magnetic performance of toroidal wound cores made from grain oriented 3% SiFe electrical steel. From a sample of 40 cores with dimensions ranging from 35 to 160 mm outer diameter, 25 to 100 mm inner diameter and JO to 70 mm strip width and a flux density range of 0.1 to 1.7 T have been obtained and used as training data to a generalised feedforward neural network.

Rule- based fuzzy classification using query processing

Abstract: This paper describes the derivation of fuzzy classification rules based on c-means fuzzy clustering algorithm as results that are induced of fuzzy clusters. Each fuzzy cluster is associated with a fuzzy classification rule in which fuzzy sets are obtained by projecting the cluster to one-dimensional domains. In order to provide a unique assignment of data to a defined class it is suggested to use the fuzzy query processing executed on the base of induced linguistic fuzzy classification rules. This approach has been applied to fuzzy classification of population where fast and efficient assignment as well as the rank of a data in the same class is supplied.