Journal of Engineering and Sustainable Development (JEASD)

The effects of loss tangent, dielectric substrate permittivity and thickness on the electrical properties of circular microstrip antenna (CMSA) excited by a coaxial-feed have been investigated using cavity model. Accuracy of the present results of resonance frequency, input resistance, bandwidth, efficiency, gain, and directivity are compared with previous work which has been done theoretically and experimentally.

This study is concerned with the behavior of beams on elastic foundation using finite element methods. The nonlinear behavior for reinforced concrete was taken into account addition to the nonlinear contact behavior of elastic foundation. As known, the elastic foundation cannot carry the tensile contact pressure, this pressure will be ignored when it occurs and then substituting zero value for the spring constant. It was found that the nonlinear behavior of materials would have low effect on deflection when compared with linear behavior. In contrast, the nonlinear contact behavior of elastic foundation would give deflection values greater than the linear behavior. A computer program (written by the researcher) is used for this purpose, where the cross-section properties can be changed such as different thicknesses and reliable results are obtained. Moreover, in the case of exiting tensile contact pressure between the surfaces and using the linear material behavior, the deflection with load will be nonlinear.

The topological design of networks in this work consists of finding a topology (directed and undirected links flow) that improve both the reliability index and increase the available shortest paths in the network without overloading the routing table or network with more links. This paper proposes a procedure for generating a topology between ring and full-mesh topology which is the partial-mesh. This optimization work was done using the principle of Social Network Analysis (SNA) by focusing on the network betweenness centralization to improve the reliability. The implementation of this work has been subjected to node/link failures before the optimization to find the important (critical) nodes links and after the design in order to test the validity of the improved network.

The aim of this work is to study the effect of variation of air temperature on the performance parameters and on volumetric efficiency of diesel engine. The experimental measurement were carried out on this engine at different air temperature 25-85oC and at different engine speed from 1000-2000rpm. The results of experimental measurement show that a decrease (8-15%) in the volumetric efficiency when sucked air temperature change from 25-85oC. It is also found that the engine output and torque decrease at increasing the sucked air temperature while specific fuel consumption, exhaust temperature and exhaust emission are increased. The results of the experimental work were compared with result of a mathematical model and a good agreement was found.

This paper gives the design and implementation of iterative and non-iterative decoders of serially concatenated block and convolutional coding schemes. The maximum likelihood (ML) decoder is implemented by applying Viterbi algorithm to trellis of the code. The performance of non-iterative decoder has been improved by using soft input soft output (SISO) ML-decoder as inner decoder and soft decision decoder as output decoder. Iterative SISO ML decoding of product codes is implemented using Pyndiah’s iterative decoder. The log-maximum a posteriori (Log-MAP) decoder is used in iterative decoding of serially concatenated codes (SCCs). To assess the performance of iterative and non-iterative decoders, simulation results for serially concatenated codes transmitted over AWGN channel, with low SNRs (power limited channel like deep space communication channel), are presented. The simulation process includes studying the bit error rate (BER) performances of serially concatenated codes with different parameters like, code dimension, minimum Hamming distance of the outer code, number of trellis sections (for block codes), number of memories, free distance, and encoder type (for convolutional codes). The influence of these parameters on interleaving gain and bit error rate of iterative and non-iterative decoders is discussed.

The research aimed at determining the optimal control device in order to decrease seepage under hydraulic structures. The finite-element method is used to analyze seepage through porous media below hydraulic structures with blanket, cut-off, or filter trench as seepage control devices. The effect of length and location of the control devices is investigated.
The formulated optimization model is applied to a hypothetical case study. The optimization problem is solved by the Lagrange-multiplier method to find the minimum costs of control devices with safe exit gradient and uplift pressure.
For a hydraulic structure with different control devices, the minimum total cost has been achieved when using a filter trench, while the maximum total cost was when a downstream cut-off is used.

Face recognition is an important and fundamental problem in computer vision, and there have been many attempts to address it. Correlation and high information redundancy in face images result in inefficiencies when such images are used directly for recognition. In this paper, an efficient hybrid approach to face recognition is presented, which combines image compression and neural network (NN) techniques together. The compression is achieved by applying fast discrete cosine transforms (DCTs) to reduce image information redundancy because only a subset of the transform coefficients are necessary to preserve the most important facial features such as hair outline, eyes and mouth. The compressed transform coefficients are used for back propagation NN classification. A high recognition rate can be achieved by using a very small proportion of transform coefficients. This makes DCT-based face recognition much faster than other approaches. The proposed system is implemented and tested using gray-scale images contains 40
distinct persons, each person having 10 different images and it gives good performance at high speed.

Numerical and experimental study was carried out on heat transfer enhancement using a slender delta wing vortex generator to generate longitudinal vortices in a rectangular duct. Numerically, laminar with constant wall temperature was considered. Effect of angle of attack of the wing (from 0.0 to 56.5 degree) on the Spain-wise average Nusselt number and the span wise average skin friction coefficient were investigated. Numerical results demonstrate similar behavior to the published results of other investigators. Experimentally, effect of angle of attack (from 0.0 to 56.5 degree) of the vortex generator, wing aspect ratio of the vortex generator (from 0.5 to 2.0) and wing width to duct width (from 0.25 to 0.5) on the heat transfer process for laminar flow (Re = 750 to 2700)
and turbulent flow (Re = 4100 to 7950) were investigated. Both numerical and experimental results show the enhancement of heat transfer but experimental results show higher values of Nusselt number compared with the numerical results.

This paper introduces the design of a digital circuit, which employs a non-linear analog-to-digital converter technique useful to measure the compressive strength of concrete. The output is in binary coded decimal suitable for readout purposes and related to the velocity of the ultrasonic pulse transmitted through the material.

This paper is intended to compare the design requirements of the structural building codes from safety and economical point of view. Three different famous structural building codes have been adopted. These are the ACI 318M-02, BS8110:1985, and Euro Code2:1992. These codes have been compared to the strength design requirements of structural elements. The comparison includes safety provisions, flexural design, shear design, and column design. Throughout this study elaborated design models and criteria of the considered codes have been exhibited. Although the principles contained in these codes are basically the same, they differ in detail. The comparison between results has shown that EC2 is more liberal in partial safety factors and strength design than ACI Code. After following this study, design engineers will discover easily that the transition among codes is not a difficult process.

A comparison between nonparametric Wilcoxon tests with time-frequency coded signal in detecting a train of narrow-band signal pulses on a background of Gaussian distribution clutter is made. The detection performance is derived, and shows a gain in Signal-to-Noise.Ratio about (5-10) dB for the same probability of detection , and a given probability of false alarm , using the number of return pulses M as a parameter.

Building works are the most important action in the construction field for the economic sector and quality control is considered as the master key to execute the actions according to the required specification. In building works, constructional locations lack the application the quality control and assurance quality, and there is misunderstanding and weakness in the applications of quality control for the employees in this field. In order to achieve the objective of the study, literatures and researches concerning the quality control, specification and inspection have been dealt with. From the information obtained, an expert system has been designed which contains base information to control the main items for building works. In order to get benefit of computer and to achieve the best usage of the system, a computer program is designed to show the necessary information for the items implementation.