Print ISSN: 1814-6120

Online ISSN: 2311-8385

Volume 5, Issue 1

Volume 5, Issue 1, Autumn 2005, Page 1-120


OPTIMAL DESIGN OF REINFORCED CONCRETE T-BEAM FLOORS

Zainab Abdulelah; Alaa Chaseb Galeb; Naseer Abdulsalam Ibrahim; Nabeel Ahduulrazzaq Jasim

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 1-16

Mathematical programming techniques have been used to minimize the cost of reinforced concrete T- bearn floor, The floor system consists of one way continuous slab and simply supported T- beams. The study presents a formulation based on elastic analysis followed by the ultimate strength method of design with the consideration of serviceability constraints as per ACI Code, The formulation ol optimization problem has been made by utilizing the interior penalty function method as an optimization method with the purpose of minimizing the objective function representing the Cost of one-meter length of the floor system. The cost includes cost of concrete. reinforcement, and formwork. The design variables considered in this study are the dimensions and the amounts of reinforcement for the slab and beams, in addition to the spacing of the beams. Many examples are solved to show the effect of these design variables on the optimum solution of the floor system. The effect on the optimum design of the compressive strength of concrete, yield strength of steel, concrete cost ratios, and formwork cost ratios has also been studied.

Dynamic Analysis of Offshore Structures with the Effect of Soil-Structure Interaction

Samoel M. Saleh; Mohamed j.K.Essa; Anis A. Mohamed Ali

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 42-54

In the present study, the dynamic analysis of jacket type offshore structures under the action of sea waves is carried out. The finite element method is adopted for the solution of the problem. The effect of soil-structure interaction on the dynamic behavior of the offshore structure is taken into account due to the deformations of the soil caused by the motion of the structure, which in turn modify the response of the structure. The supporting elastic foundation is represented by Win kier type model having normal and tangential moduli of sub grade reaction. These moduli may be constant or varying linearly or nonlinearly along the embedded length of the piles that support the offshore structure. The pile tip conditions are also considered A time domain solution is recommended. The generalized Morison ‘s equation is used to calculate the wave forces and Airy ‘s linear theory to describe the flow characteristics, Both free and forced vibration analyses are studied. The dynamic response has been obtained by modal analysis in conjunction with Wilson- method. As an example, a modified model of an actual jacket type offshore platform is analyzed under the action of wave forces.

SOFT SWJTCHING PWM AC/DC CONVERTER

M.M. Ibrahim; R.S.Fyath; A.S.Alsheraidah

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 55-69

This paper presents a PWM AC/DC buck converter circuit incorporating a frontend rectifier followed by a DC/DC converter. Two transistors are used as a main and auxiliary switches. The proposed circuit provides zero-current (ZC) turn ON and zero-current/zero-voltage (ZCZV) turn OFF to the two transistors, besides zero-voltage turn ON to two diodes. Numerical methods are used to analyse and determine the performance of the converter system. A feedforward technique is employed to improve the performance of the converter over a range of output power.

Neural Networks based PID Controller

Turki Y. Abdalla

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 70-76

This paper considers the neural network based PID controller. The learning and generalization properties of neural network are utilized in improving the performance of a conventional PID controller. Two different schemes arc introduced. Both schemes are studied and their performances are comparatively evaluated on an example for uncertain system.

Performance of First-order Loops Incorporating Time Delay

Gaida A.AL-Suheal

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 77-86

The influence of time delay on the statistical behavior of the first-order phase-locked-loop is investigated in VHF and UHF synchronous communication systems. The Fokker-Plank equation has been proposed to estimate the probability density function (pdf) of phase fluctuations as well as the average time to Loss lock in the presence of noise. The result reveal that the degradation in the loop performance occurs under various conditions of detuning when the inherent time delay is present.

Performance Prediction for Fiber-Fed Microcellular Radio Network

A.A.W.Al-Saffer; R.S.Fyath; M.Sh.Abed

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 87-99

- The use of fiber-optic links as the connecting media in wireless microcellular networks can be provide uniform radio Coverage to spatially distributed mobile users in cost effective manner. This paper investigates theoretically the performance of fiber distribution system for mobile phone networks that uses a single high power Nd:YAG laser in the base station and shared by many rnicrocells. Analytical expressions are derived for the bit-error-rate (BER) floor characteristics and optimum operating conditions. The results indicate clearly that the laser power can be reduced significantly when the modulation index is optimized.

CHARACTERISTIC OF FLOW OVER SEMICIRICULAR SUBMERGED WEIR

G.H.Hayawi

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 100-109

The main objects of this investigation are to obtain convenient expressions for the estimation of discharge coefficient for submerge flow over concave and convex semicircle shape crested weirs. Sixteen weir models were constructed and tested. these, models were classified into four groups. The first and second groups were of single cycles having concave and convex shapes, respectively, with curvature radius of I 5cm.The third and forth groups were of double cycles having concave and convex shapes, respectively, with curvature radius of 7.5cm.Ln each group the weir height, p was varied four times 10cm, 7.5cm, 5cm and 2.5cm Based on results of this study it was found that for constant weir radius, R, the discharge coefficient, Cd, increases with the increase in the relative upstream head, hip, while, for constant upstream head, weirs of small heights give higher discharge coefficient than those of large height .Two general expressions were obtained for the estimation of Cd as function of, relative upstream head ,h/p, and relative radius, R/P, one expression for single and double cycle concave submerged weirs and the other for convex submerged weirs.

Soil Stabilization With Palm Fibers

Lamia Abdul Jaleel; Rawdan J.Rawdan; Vegain Simon Marcar

Basrah Journal for Engineering Science, Volume 5, Issue 1, Pages 110-120

This study concerns with the improvement of soils in Basrah area. Two types of soil have been selected; the first from Garmatt Au place and the second type from Abu Al-Khasseeb place. Natural (palm) fibers are used in stabilization of these soils. These fibers were added by different percentages (0, 1,2, and 3%) by weight of dry soil so as to improve soil properties.
The selected soil are subjected to different tests such as liquid and plastic limit, specific gravity, unconfined compressive strength, compaction test.
It was found that the addition of fibers to the soil affects compaction characteristics by decreasing maximum thy density and increasing optimum moisture content for both types of soils. The unconfined compressive strength increased with more addition of fibers .The affect of fibers content on swelling ,the swelling percent reduced especially during first days of the test.