Mathematical and Computational Applications

298 KiB

Open AccessArticle

The Evaluation of Thermal Stresses in Thermoplastic Laminated Composites with Different Square Holes

by Faruk Sen, Mustafa Toparlı and N. Sinan Köksal

Math. Comput. Appl. 2007, 12(1), 59-68; https://doi.org/10.3390/mca12010059 - 01 Apr 2007

Cited by 3 | Viewed by 998

In this study, a thermal stress analysis was evaluated on symmetric angle-ply laminated thermoplastic composite plates that were having different square hole dimensions. The temperature loading was selected uniformly. Besides, it was applied with various values that were chosen as 50, 60, 70, [...] Read more.

In this study, a thermal stress analysis was evaluated on symmetric angle-ply laminated thermoplastic composite plates that were having different square hole dimensions. The temperature loading was selected uniformly. Besides, it was applied with various values that were chosen as 50, 60, 70, 80, 90, 100 °C, because of the fact that the effect of increasing uniform temperature on thermal stresses was examined. The width plate-to-the width square hole, a/b, ratios were changed as 2, and 4. Thermoplastic laminated composite plates were assumed to be simple supported. Laminated plates were composed of four orthotropic layers oriented with angle-ply in symmetric manner. The solution was carried out by using ANSYS finite element program. The results were showed in figures depending on applied temperatures, orientations and dimensions of square hole. Full article

138 KiB

Open AccessArticle

On the Stability of Delay Integro-Differential Equations

by Ali Fuat Yeniçerioğlu and Salih Yalçınbaş

Math. Comput. Appl. 2007, 12(1), 51-58; https://doi.org/10.3390/mca12010051 - 01 Apr 2007

Cited by 2 | Viewed by 1067

Abstract

Some new stability results are given for a delay integro-differential equation. A basis theorem on the behavior of solutions of delay integro-differential equations is established. As a consequence of this theorem, a stability criterion is obtained. Full article

136 KiB

Open AccessArticle

An Approximate Method for Free Vibration Analysis of Multi-Bay Coupled Shear Walls

by Kanat Burak Bozdogan and Duygu Öztürk

Math. Comput. Appl. 2007, 12(1), 41-50; https://doi.org/10.3390/mca12010041 - 01 Apr 2007

Cited by 3 | Viewed by 1348

Abstract

In this study, an approximate method based on the continuum approach and transfer matrix method for free vibration analysis of multi bay coupled shear walls is presented. In this method the whole structure is idealized as sandwich beam. Initially the differential equation of [...] Read more.

In this study, an approximate method based on the continuum approach and transfer matrix method for free vibration analysis of multi bay coupled shear walls is presented. In this method the whole structure is idealized as sandwich beam. Initially the differential equation of this equivalent sandwich beam is written then shape function for each storey can be obtained by the solution of differential equations. By using boundary conditions and storey transfer matrices which are obtained by these shape functions, system modes and periods can be calculated. Reliability of the study is shown with a few examples. A computer program has been prepared in MATLAB computer algebra system and numerical samples have been solved for demonstration of the reliability of the method. The results of the samples display the convergence of the present method to the other methods used in literature. Full article

158 KiB

Open AccessArticle

A New Method for Extracting 3D Solid Models of Objects Using 2D Technical Drawings

by İbrahim Çayıroglu, Abdullah Çavusoglu and Veli Çelik

Math. Comput. Appl. 2007, 12(1), 31-39; https://doi.org/10.3390/mca12010031 - 01 Apr 2007

Cited by 1 | Viewed by 1124

Abstract

In this study, a new method called “3D-Space” have been developed to obtain 3D models of prismatic machine parts using 2D technical drawings. The algorithm basicaly works in the following manner: 3 basic views (i.e. top, front, left side) of an object are [...] Read more.

In this study, a new method called “3D-Space” have been developed to obtain 3D models of prismatic machine parts using 2D technical drawings. The algorithm basicaly works in the following manner: 3 basic views (i.e. top, front, left side) of an object are supplied as inputs while the output is a 3D solid view of corresponding object. To start with a raw bounding box spatially big enough to contain the complete final object is taken. Following the operations executed on it, the result is the 3D solid view of the 2D drawings. The basic views of the object are used to determine the nature of the operation to be applied on the raw entity. A feedback mechanism is also incorporated into the system to check the correctness of the final product. The results show that in most of the cases the algorithm works as expected. However there are some restrictions which are given in the text. Full article

166 KiB

Open AccessArticle

A Generalized KBM Method for Strongly Nonlinear Oscillators with Slowly Varying Parameters

by Jianping Cai

Math. Comput. Appl. 2007, 12(1), 21-30; https://doi.org/10.3390/mca12010021 - 01 Apr 2007

Cited by 3 | Viewed by 1242

Abstract

A generalized Krylov-Bogoliubov-Mitropolsky (KBM) method is extended for the study of strongly nonlinear oscillators with slowly varying parameters. The asymptotic amplitude and phase are derived and then the asymptotic solutions of arbitrary order are obtained theoretically. Cubic nonlinear oscillators with polynomial damping are [...] Read more.

A generalized Krylov-Bogoliubov-Mitropolsky (KBM) method is extended for the study of strongly nonlinear oscillators with slowly varying parameters. The asymptotic amplitude and phase are derived and then the asymptotic solutions of arbitrary order are obtained theoretically. Cubic nonlinear oscillators with polynomial damping are studied in detail. Three examples are considered: a generalized Van der Pol oscillator, a Rayleigh equation and a pendulum with variable length. Comparisons are also made with numerical solutions to show the efficiency and accuracy of the present method. Full article

187 KiB

Open AccessArticle

An Analytical Model of Mountain Wave for Wind with Shear

by Naresh Kumar

Math. Comput. Appl. 2007, 12(1), 11-19; https://doi.org/10.3390/mca12010011 - 01 Apr 2007

Cited by 2 | Viewed by 1024

Abstract

A 2-D analytical mesoscale hydrostatic model of a stably stratified orographic barrier has been considered. Expressions for surface pressure perturbation, mountain drag and energy flux across Pirpanjal mountains of Kashmir valley for variable wind have been derived. These are further evaluated for realistic [...] Read more.

A 2-D analytical mesoscale hydrostatic model of a stably stratified orographic barrier has been considered. Expressions for surface pressure perturbation, mountain drag and energy flux across Pirpanjal mountains of Kashmir valley for variable wind have been derived. These are further evaluated for realistic vertical profile of wind and temperature. Also study has been extended to obtain all these parameters for different vertical wind profile. Full article

159 KiB

Open AccessArticle

Multichannel Blind Deconvolution Using a Generalized Gaussian Source Model

by A. S. Abu-Taleb, E. M. E. Zayed, W. M. El-Sayed, A. M. Badawy and O. A. Mohammed

Math. Comput. Appl. 2007, 12(1), 1-9; https://doi.org/10.3390/mca12010001 - 01 Apr 2007

Viewed by 1158

Abstract

In this paper, we present an algorithm for the problem of multi-channel blind deconvolution which can adapt to un-known sources with both sub-Gaussian and super-Gaussian probability density distributions using a generalized gaussian source model.
We use a state space representation to model the [...] Read more.

In this paper, we present an algorithm for the problem of multi-channel blind deconvolution which can adapt to un-known sources with both sub-Gaussian and super-Gaussian probability density distributions using a generalized gaussian source model.
We use a state space representation to model the mixer and demixer respectively, and show how the parameters of the demixer can be adapted using a gradient descent algorithm incorporating the natural gradient extension. We also present a learning method for the unknown parameters of the generalized Gaussian source model. The
performance of the proposed generalized Gaussian source model on a typical example is compared with those of other algorithm, viz the switching nonlinearity algorithm
proposed by Lee et al. [8]. Full article

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Math. Comput. Appl., Volume 12, Issue 1 (April 2007) – 7 articles , Pages 1-68

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