Mathematical and Computational Applications

4920 KiB

Open AccessArticle

Some Renovations in Transient Analysis of Transmission Lines by State-Space Techniques

by M. Salih. Mamiş and Muhammet Köksal

Math. Comput. Appl. 1996, 1(1), 181-190; https://doi.org/10.3390/mca1010181 - 01 Jun 1996

Cited by 1 | Viewed by 1436

A method for transient analysis of single phase transmission lines based on state-space technique is presented. Transmission lines are considered as the interconnection of many lumped parameter sections. By this approach state equations are formulated for the system by choosing the capacitor voltages [...] Read more.

A method for transient analysis of single phase transmission lines based on state-space technique is presented. Transmission lines are considered as the interconnection of many lumped parameter sections. By this approach state equations are formulated for the system by choosing the capacitor voltages and inductor currents as the state variables. These equations are solved by state space techniques to compute steady-state and transient responses of transmission lines for various source and load connections. A computer program called LPTLAP (Lumped Parameter Transmission Line Transient Analysis Program) has been prepared for both formulation and solution steps. Full article

3030 KiB

Open AccessArticle

Examination of Temperature Distribution as a Result of Hard-Brazing of Two Different Materials by Finite Elements Method

by Salim Şahin and Mustafa Toparlı

Math. Comput. Appl. 1996, 1(1), 172-180; https://doi.org/10.3390/mca1010172 - 01 Jun 1996

Viewed by 1123

Abstract

Knowing the temperature effect on machine construction is the first step at material selection and planing machine parts exposed to temperature effect above normal conditions. Since joining processes such as welding and hard-brazing were done at high temperatures, abrupt variations in temperature distributions [...] Read more.

Knowing the temperature effect on machine construction is the first step at material selection and planing machine parts exposed to temperature effect above normal conditions. Since joining processes such as welding and hard-brazing were done at high temperatures, abrupt variations in temperature distributions take place. Because of these temperature variations inner structure and shape changes occur in material. If two different materials are joint, these problem becomes more important due to mismatch of physical properties of materials joint. Because of this reason, temperature distribution must be known at these kind of joinings.

In this study only the temperature distribution calculations around the joining zone were carried out. In the future step the thermal stress and residual stress distributions during and after joining process will be calculated. For this purpose steel-brass material couple were chosen and the materials as thin plates were hard-brazed. The joining parts of this material couple were heated upto hard- brazing temperature and then cooled in air. In this numeric study finite elements method was used and the programming language was chosen Fortran77. In modelling two dimensionel four nodes rectangular elements were selected. Full article

3737 KiB

Open AccessArticle

Comparing Artificial Neural Networks (ANN) Image Compression Technique with Different Image Compression Techniques

by Bekir Karlık, Serkan Aydın and İlker Kılıç

Math. Comput. Appl. 1996, 1(1), 165-171; https://doi.org/10.3390/mca1010165 - 01 Jun 1996

Viewed by 1309

Abstract

In this paper it is presented that, 256 × 256 16 gray level images can be compressed fast and efficiently by using neural networks . Compression results were compared with the other methods according to mean square error (MSE) and visual of the [...] Read more.

In this paper it is presented that, 256 × 256 16 gray level images can be compressed fast and efficiently by using neural networks . Compression results were compared with the other methods according to mean square error (MSE) and visual of the image and it is seen that by further works on ANN the images can be compressed better. Full article

2658 KiB

Open AccessArticle

An Artificial Neural Network Based Preestimation Fitler for Bad Data Defection, Identification and Elimination in State Estimation

by Mehmet Uzunoğlu, Celal Kocatepe and Recep Yumurtaca

Math. Comput. Appl. 1996, 1(1), 159-164; https://doi.org/10.3390/mca1010159 - 01 Jun 1996

Viewed by 1189

Abstract

State estimators are vitally important in energy control centers. The measurements that come from control system are generally analysed by a state estimator. Since there can always be bad measurements in the system, estimated value and the true value of the state estimator [...] Read more.

State estimators are vitally important in energy control centers. The measurements that come from control system are generally analysed by a state estimator. Since there can always be bad measurements in the system, estimated value and the true value of the state estimator can be far from each other. In this paper, by using an artificial neural network (ANN), a bad data detection, identification and then elimination preestimation filter is outlined. Full article

1744 KiB

Open AccessArticle

E2/M1 Multipole Mixing Ratios of 162Dy Nucleus in Rotation Vibration Model

by Mehmet Baylan, İhsan Uluer, Atalay Küçükbursa and İsmail Maraş

Math. Comput. Appl. 1996, 1(1), 154-158; https://doi.org/10.3390/mca1010154 - 01 Jun 1996

Viewed by 1150

Abstract

The extended rotation-vibration model containing different deformations for protons and neutrons is applied to ¹⁶²Dy nucleus. The mixing ratios we obtained for the E2/Ml transitions are in reasanably good agreement with previous experimental and theoretical values. Full article

3550 KiB

Open AccessArticle

Vibration Control Methods by Mode Localization: A Comparative Study

by Ahmet S. Yiğit and Mohammad Khalid

Math. Comput. Appl. 1996, 1(1), 147-153; https://doi.org/10.3390/mca1010147 - 01 Jun 1996

Viewed by 1198

Abstract

This study is an attempt to generalize different active mode localization strategies. It is demonstrated that similar results can be obtained by either a passive design which exhibits normal mode localization or by an active controller which is obtained by employing some of [...] Read more.

This study is an attempt to generalize different active mode localization strategies. It is demonstrated that similar results can be obtained by either a passive design which exhibits normal mode localization or by an active controller which is obtained by employing some of the recently proposed design methods of active control methods. Different active control methods proposed for achieving mode localization are com-pared. It is shown that all active control methods proposed for mode localization can be considered as special cases of a general control method called "Space Domain Control". Full article

2740 KiB

Open AccessArticle

Free Vibrations of Rotating Adhesively Bonded Orthotropic Plates

by A. Kadir Yavuz and Temel Kotil

Math. Comput. Appl. 1996, 1(1), 140-146; https://doi.org/10.3390/mca1010140 - 01 Jun 1996

Cited by 3 | Viewed by 1233

Abstract

In this study, free vibration analysis of rotating adhesively bonded specially orthotropic plates is investigated. A first-order shear-deformation plate theory including geometric nonlinearities in the form of the von Karman strains and the effects ofrotatory inertia and Coriolis is used to predict the [...] Read more.

In this study, free vibration analysis of rotating adhesively bonded specially orthotropic plates is investigated. A first-order shear-deformation plate theory including geometric nonlinearities in the form of the von Karman strains and the effects ofrotatory inertia and Coriolis is used to predict the free vibration frequencies and mode shapes of the system under consideration. In the analytical model, the thin interlaminar adhesive layer is taken into account in the form of mechanical springs. The governing non-linear equations of motion and the appropriate boundary conditions are derived by means of the variational method in conjunction with Hamilton's Principle. Full article

1924 KiB

Open AccessArticle

Determination of Mathematical Model of Electric Power System Using Linear Graph

by Adem Ünal

Math. Comput. Appl. 1996, 1(1), 134-139; https://doi.org/10.3390/mca1010134 - 01 Jun 1996

Viewed by 1183

Abstract

The transformation of a physical system to mathematical base is very important due to analysis of the systems behaviour. In this study an electric power system is considered, and this system is characterized with first-order differantial eqautions therefore stateequations which define behaviour of [...] Read more.

The transformation of a physical system to mathematical base is very important due to analysis of the systems behaviour. In this study an electric power system is considered, and this system is characterized with first-order differantial eqautions therefore stateequations which define behaviour of the system for any instant "t" are obtained. Full article

3228 KiB

Open AccessArticle

Nonlinear Structural Response of Laminated Composite Panels Subjected to Blast Loadings

by Halit S. Türkmen, Zahit Mecitoğlu and Oğuz Borat

Math. Comput. Appl. 1996, 1(1), 126-133; https://doi.org/10.3390/mca1010126 - 01 Jun 1996

Cited by 1 | Viewed by 1414

Abstract

'This paper presents a theoretical analysis and correlation with numerical results of the displacement time histories of laminated composite panels exposed to normal blast shock waves. Nonlinear dynamic equations of the cylindrically curved laminated panels are derived by the use of the Lagrange [...] Read more.

'This paper presents a theoretical analysis and correlation with numerical results of the displacement time histories of laminated composite panels exposed to normal blast shock waves. Nonlinear dynamic equations of the cylindrically curved laminated panels are derived by the use of the Lagrange equations in the frame of Love's theory of thin shells. The governing equations of the laminated curved panel are solved by Runge-Kutta method. In addition, ANSYS finite element software is used to obtain displacement time history numerically. The effect ofloading conditions and geometrical properties is examined on the dynamic behavior. Full article

2738 KiB

Open AccessArticle

Conbustion Modelling in Dedicated Naturel Gas Engines

by Hakan Serhad Soyhan and Cern Soruşbay

Math. Comput. Appl. 1996, 1(1), 119-125; https://doi.org/10.3390/mca1010119 - 01 Jun 1996

Viewed by 1220

Abstract

Combustion characteristics of a spark ignition engine utilizing natural gas as a fuel has been investigated by a mathematical model employing a global kinetic reaction mechanism for the oxidation of methane. In-cylinder flow mechanism is calculated by applying the Conchas algorithm in order [...] Read more.

Combustion characteristics of a spark ignition engine utilizing natural gas as a fuel has been investigated by a mathematical model employing a global kinetic reaction mechanism for the oxidation of methane. In-cylinder flow mechanism is calculated by applying the Conchas algorithm in order to obtain the effects of various operational characteristics and design parameters concerning the combustion chamber. The results obtained from the model provided an optimization tool for engine modifications. Full article

3474 KiB

Open AccessArticle

Neural Network Approach for the Characterisation of the Active Microwave Devices

by Hamid Torpi, Filiz Güneş and Fikret Gürgen

Math. Comput. Appl. 1996, 1(1), 113-118; https://doi.org/10.3390/mca1010113 - 01 Jun 1996

Viewed by 1214

Abstract

Small-signal and noise behaviour of an active microwave device is modeled through the neural network approach for multiple bias/configurations.Here ,the device is modelled by a black box whose small signal and noise parameters are evaluated through a neural network,based upon the fitting of [...] Read more.

Small-signal and noise behaviour of an active microwave device is modeled through the neural network approach for multiple bias/configurations.Here ,the device is modelled by a black box whose small signal and noise parameters are evaluated through a neural network,based upon the fitting of both of these parameters for the multiple
bias or configuration. The concurrent modelling procedure does not require to solve device pbysics equations repeatedly during optimization. Compared to the existing device modelling techniques, the proposed approach has the capability to make bighdimensional models for higbly nonlinear devices. Full article

3127 KiB

Open AccessArticle

Active and Reactive Power Adjustment of a Synchronous Generator Connected to Infinite Bus System by Fuzzy Logic Controller

by Muğdeşem Tanrıöven, Erdin Gökalp and Celal Kocatepe

Math. Comput. Appl. 1996, 1(1), 105-112; https://doi.org/10.3390/mca1010105 - 01 Jun 1996

Viewed by 1280

Abstract

The fuzzy logic controller based on the fuzzy set theory provides a useful tool for converting the linguistic control from the expert knowledge into automatic control rules [1]. By using fuzzy automatic rules from the heuristic or mathematical strategies, complex processes can be [...] Read more.

The fuzzy logic controller based on the fuzzy set theory provides a useful tool for converting the linguistic control from the expert knowledge into automatic control rules [1]. By using fuzzy automatic rules from the heuristic or mathematical strategies, complex processes can be controlled effectively in many situations. But the most important and difficult point is how to obtain the proper control rules for a given system. In this study, active and reactive power control of a generator connected to infinite bus system was fulfilled effectively by the fuzzy logic controller. And the software of the system's simulation results were given. Full article

3389 KiB

Open AccessArticle

Computer Aided Constrained Optimisation of Cutting Conditions in Drilling Operations on a CNC Lathe by Using Geometric Programming

by A. İhsan Sönmez, Adil Baykasoğlu and İ. Hüseyin Filiz

Math. Comput. Appl. 1996, 1(1), 97-104; https://doi.org/10.3390/mca1010097 - 01 Jun 1996

Cited by 4 | Viewed by 1304

Abstract

This paper discusses the use of the geometric programming method to determine the optimum values of cutting speed and feed rate which yield minimum cost in a drilling operation that is performed on a CNC lathe, During the formulation of the problem a [...] Read more.

This paper discusses the use of the geometric programming method to determine the optimum values of cutting speed and feed rate which yield minimum cost in a drilling operation that is performed on a CNC lathe, During the formulation of the problem a number of constraints are considered. Full article

5451 KiB

Open AccessArticle

Dynamic Response of Composite Cylindrical Shells to Shock Loading

by Ömer Soykasap, Zahit Mecitoğlu and Oğuz Borat

Math. Comput. Appl. 1996, 1(1), 85-96; https://doi.org/10.3390/mca1010085 - 01 Jun 1996

Cited by 2 | Viewed by 1490

Abstract

In this paper, dynamic response of composite cylindrical shells subjected to shock loading is studied analytically. The equations of motion are based on Sanders theory of thin shell. The effects of transverse shear deformation and rotatory inertia are taken into account. The circular [...] Read more.

In this paper, dynamic response of composite cylindrical shells subjected to shock loading is studied analytically. The equations of motion are based on Sanders theory of thin shell. The effects of transverse shear deformation and rotatory inertia are taken into account. The circular cylindrical thin shell with simply supported ends is subjected to a shock load, represented by an axially symmetric moving load at a constant speed along the longitudinal direction. The governing equations are solved analytically using the Assumed-Modes Method. The influences of geometrical parameters and composite material properties of circular cylindrical shells on the dynamic response are studied. Full article

4857 KiB

Open AccessArticle

Dynamic Behavior of a Stiffened Laminated Conical Shell under Hygrothermal Loads

by Zahit Mecitoğlu and Hasan Örenel

Math. Comput. Appl. 1996, 1(1), 73-84; https://doi.org/10.3390/mca1010073 - 01 Jun 1996

Viewed by 1274

Abstract

The dynamic behavior of a stiffened composite laminated conical thin shell under hygrothermal loads is studied numerically. The governing equations of truncated conical shell are based on the Donnell-Mushtari theory of thin shells including the transverse shear deformation and rotary inertia. The extension-bending [...] Read more.

The dynamic behavior of a stiffened composite laminated conical thin shell under hygrothermal loads is studied numerically. The governing equations of truncated conical shell are based on the Donnell-Mushtari theory of thin shells including the transverse shear deformation and rotary inertia. The extension-bending coupling is taken into account in the equations. The composite laminated conical shell is also reinforced at uniform intervals by elastic rings andlor stringers. The stiffening elements are relatively closely spaced, and therefore the stiffeners are "smeared out" along the conical shell. The inhomogeneity of material properties because of moisture and temperature is taken into account in the constitutive equations. The equations of laminated composite conical shell are solved by the use of finite difference method The effect of moisture is examined on the dynanlic behavior. The accuracy of results is tested by certain earlier results and an agreement is found. Full article

3532 KiB

Open AccessArticle

Power Factor Correction of Synchronous Motor Using Fuzzy Logic

by Arş. Gör. E. Kılıç and I. H. Altaş

Math. Comput. Appl. 1996, 1(1), 66-72; https://doi.org/10.3390/mca1010066 - 01 Jun 1996

Cited by 1 | Viewed by 1441

Abstract

Application of fuzzy logic theory in power factor correction of a synchronous motor is investigated in this paper. The power factor measured at the input terminals of a synchronous motor is adjusted to a required value using a fuzzy logic controller (FLC). If [...] Read more.

Application of fuzzy logic theory in power factor correction of a synchronous motor is investigated in this paper. The power factor measured at the input terminals of a synchronous motor is adjusted to a required value using a fuzzy logic controller (FLC). If the measured power factor is different than the required reference value an error signal is generated. This error signal is evaluated by FLC to obtain a control signal for the synchronous motor excitation circuit since the power factor of a synchronous motor can be controlled and held at a desired value by adjusting the excitation current. Therefore it seem, to be more economic than other methods for some special applications. Full article

2724 KiB

Open AccessArticle

Satisfaction of Boundary Conditions on Complex Channel Walls with Quadratic Minimizaion Method

by E. Fuad Kent

Math. Comput. Appl. 1996, 1(1), 60-65; https://doi.org/10.3390/mca1010060 - 01 Jun 1996

Viewed by 1093

Abstract

Numerical analysis of cellular two-dimensional Stokes flow induced by rotation of a circular cylinder in a V-shaped channel bounded by a cylindrical surface has been made. In the numerical calculations, series in terms of polar coordinates are used to represent the stream function [...] Read more.

Numerical analysis of cellular two-dimensional Stokes flow induced by rotation of a circular cylinder in a V-shaped channel bounded by a cylindrical surface has been made. In the numerical calculations, series in terms of polar coordinates are used to represent the stream function and quadratic minimization method is employed to satisfy the outer boundary conditions on the channel walls. Numerical results are presented in the form of streamline patterns. Full article

4688 KiB

Open AccessArticle

Algebraic Approach to Transformations on Hypercube System

by Ş. Ş. Kahramanlı and N. M. Allahverdi

Math. Comput. Appl. 1996, 1(1), 50-59; https://doi.org/10.3390/mca1010050 - 01 Jun 1996

Cited by 1 | Viewed by 1361

Abstract

In this study some algebraic transformations on hypercube system are proposed. The presented transformations of forbidden subcubes provide defining set of all maximal and nonfaulty subcubes, and subset of minimal and nonfaulty subcubes included certain given vertices. It provides formal and simple findings [...] Read more.

In this study some algebraic transformations on hypercube system are proposed. The presented transformations of forbidden subcubes provide defining set of all maximal and nonfaulty subcubes, and subset of minimal and nonfaulty subcubes included certain given vertices. It provides formal and simple findings of all the current sources and targets of information, and also the pathways between them. The correctness of all these transformations is proved by the aid of three theorems. In the proposed transformations there were three special operations of cube algebra applied, as subtraction, product and intersection on coordinates. Full article

2917 KiB

Open AccessArticle

The Decision of Intrauerine Growth Retardation from Ultrasonographic Examinations with Neural Networks

by Fikret Gürgen, Emrah Önal and Füsun G. Varol

Math. Comput. Appl. 1996, 1(1), 44-49; https://doi.org/10.3390/mca1010044 - 01 Jun 1996

Viewed by 1228

Abstract

Our putpose is to make decision of intrauterine growth retardation (IUGR) through single and multiple ultrasonographic fetal growth assessments using a neural network (NN). This study was undertaken to show if a feedforward NN can learn nominal growth curves of head circumference (HC), [...] Read more.

Our putpose is to make decision of intrauterine growth retardation (IUGR) through single and multiple ultrasonographic fetal growth assessments using a neural network (NN). This study was undertaken to show if a feedforward NN can learn nominal growth curves of head circumference (HC), abdominal circumference (AC), and HC/AC ratio versus gestational age and can help doctors in diagnosis ofIUGR Weekly (from 1 to 4 weeks) ultrasonographic examinations are taken as input to NN. A feedforward NN is used as a function approximator. Back propagation (BP) algorithm is used to optimize connection weights using samples from nominal curves. It was observed that a NN can improve the accuracy of the decision of IUGR by the multiple weekly examinations which mean monitoring the dynamic process of a change in size over time. It was concluded that the applicability of NNs to determination of IUGR is possible and it is a fruitfui line of inquiry for further work. Full article

3650 KiB

Open AccessArticle

The Effects of Addendum Modification Coefficient on Tooth Stresses of Spur Gear

by Durmuş Günay, Halil Özer and Alpay Aydemir

Math. Comput. Appl. 1996, 1(1), 36-43; https://doi.org/10.3390/mca1010036 - 01 Jun 1996

Cited by 2 | Viewed by 1658

Abstract

The effects of addendum modification coefficient on the root stresses of spur gear are investigated. By considering positive and negative addendum modificated gears, distributions of root stresses are determined by the finite element method. The root stresses of addendum modificated gears are compared [...] Read more.

The effects of addendum modification coefficient on the root stresses of spur gear are investigated. By considering positive and negative addendum modificated gears, distributions of root stresses are determined by the finite element method. The root stresses of addendum modificated gears are compared with those of standard gears. The problem is analyzed as one in the plane stress and, also the plane strain. Full article

2735 KiB

Open AccessArticle

Torsional Stresses in the Transverse Fillet Weld Tubular Joints

by Durmuş Günay, Alpay Aydemir and Halil Özer

Math. Comput. Appl. 1996, 1(1), 29-35; https://doi.org/10.3390/mca1010029 - 01 Jun 1996

Viewed by 1260

Abstract

Torsional stresses, τ_rθ and τ_θz, in the transverse fillet tubular weld joint subjected to torsional load have been analyzed by the finite element method using triangular and quadrilateral izoparametric axisymmetric fourier type torus finite elements. There is an axisymmetry with [...] Read more.

Torsional stresses, τ_rθ and τ_θz, in the transverse fillet tubular weld joint subjected to torsional load have been analyzed by the finite element method using triangular and quadrilateral izoparametric axisymmetric fourier type torus finite elements. There is an axisymmetry with respect to geometry and material properties but no axisymmetry with respect to the loading. With respect to material properties, two kinds of joints are considered in the study. One consists of steel tubes and steel weld material, the other steel tubes and brass weld material. All of the materials used are assumed linear-elastic. Changing the torsional stresses, along the weld legs and the weld throat, are plotted in dimensionless coordinates. Full article

3483 KiB

Open AccessArticle

The Lifts of Langrange and Hamilton Equations to the Extended Vecor Bundles

by Şevket Civalek

Math. Comput. Appl. 1996, 1(1), 21-28; https://doi.org/10.3390/mca1010021 - 01 Jun 1996

Viewed by 1113

Abstract

In this study, the vertical and complete lifts of Lagrange and Hamilton equations on the extended vector bundle have been given. Furthermore, some results on higher order mechanical systems on the extended vector bundles have been obtained. Full article

2723 KiB

Open AccessArticle

Lie Symmetries of Differential Equations by Computer Algebra

by Mehmet Can

Math. Comput. Appl. 1996, 1(1), 15-20; https://doi.org/10.3390/mca1010015 - 01 Jun 1996

Cited by 1 | Viewed by 1313

Abstract

In this paper we restrict ourselves to Lie point symmetries an applications to the fourth order generalized Burgers equation GBE4. Using computer programs under the computer algebra package MATHEMATICA we find a three dimensional solvable Lie algebra of point symmetries of the GBE4 [...] Read more.

In this paper we restrict ourselves to Lie point symmetries an applications to the fourth order generalized Burgers equation GBE4. Using computer programs under the computer algebra package MATHEMATICA we find a three dimensional solvable Lie algebra of point symmetries of the GBE4 equation. The similarity reductions due to these symmetries have also been obtained. Full article

3303 KiB

Open AccessArticle

Procedures for Aircraft Gate Assigment

by Ahmet Bolat and Khaled As-Saifan

Math. Comput. Appl. 1996, 1(1), 9-14; https://doi.org/10.3390/mca1010009 - 01 Jun 1996

Cited by 4 | Viewed by 1392

Abstract

The task of assigning arriving flights to the available gates at an airport can have a major impact on the efficiency with which the flight schedules are maintained and on the level of passenger satisfaction. In this paper, optimum and heuristic procedures are [...] Read more.

The task of assigning arriving flights to the available gates at an airport can have a major impact on the efficiency with which the flight schedules are maintained and on the level of passenger satisfaction. In this paper, optimum and heuristic procedures are developed to assign flights in such a way that the idle periods, during which gates are not utilized,. are distributed as uniformly as possible. Emprical study indicates that up to 60% improvements can be achieved over the current practice. Full article

2643 KiB

Open AccessArticle

Quality Function Deployment Approach to Satisfying Customers Demands and an Implementation at Shoes Company

by Hayri Baraçlı, Bahadir Gülsün and Ali Fuat Güneri

Math. Comput. Appl. 1996, 1(1), 1-8; https://doi.org/10.3390/mca1010001 - 01 Jun 1996

Viewed by 1277

Abstract

In our developing world, to produce high quality product and deliver these products to the customers are carried on. From this point of view, producing quality products is very important for the continuity of business companies. In manufacturing systems, considering customer demands means [...] Read more.

In our developing world, to produce high quality product and deliver these products to the customers are carried on. From this point of view, producing quality products is very important for the continuity of business companies. In manufacturing systems, considering customer demands means broadening marketshore. Customer demands are valid from designing product to the services. If the business enterprise completes these processes it will be called successful. To reflect the customer demands to the product, we use a technique called Quality Function Deployment. In this study, some basic definitions of the Quality Function Deployment are given and initial data for the implementation will be expressed. Full article

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Math. Comput. Appl., Volume 1, Issue 1 (June 1996) – 25 articles , Pages 1-190

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