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ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES

مجلة النهرين للعلوم الهندسية

ISSN: 25219154 / eISSN 25219162
Publisher: Al-Nahrain University
Faculty: Engineering
Language: Arabic and English

This journal is Open Access

About

AlNhrain Journal for Engineering Sciences is a refereed scientific engineering journal published by the College of Engineering, Nahrain University two times per year. The journal publishes the scientific output of researchers from Iraq and abroad in the fields of architectural, chemical, civil, computer, electrical, information technology, laser and optoelectronics, mechanical and medical engineering as well as in related fields. Papers written in Arabic and English are accepted and they are subjected to proper evaluation and accordingly classified as follows:
• Original research papers and papers on novel design, analysis or construction methods of great value to the engineers which include basic and practical results.
• Short communications or short discussions on papers which have already appeared in the journal provided that whose text should not exceed 800 words.

The material of the paper should not violate any intellectual property right of any person or entity and should not contain any subject matter that contravenes any laws and should meet ethical standards applicable to the research discipline.

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Contact info

Editor-in-Chief
College of Engineering Journal
Al-Nahrain University
P.O. Box 64040 , Al-Jadyriah
Baghdad-Iraq.
e-mail: journal.engineering@nahrain-eng.org
jourengnah@gmail.com
Phone: +964 (0) 7817 202 662

Table of content: 2007 volume:10 issue:1

Article
Design and Hardware Implementation of a Speech Cipher System
تصميم و تنفيذ الكيان المادي لمنظومة تشفير الكلام

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Abstract

Digital ciphering of speech signals based on one of modern cryptography algorithms, called the Rijndael algorithm, is studied and presented in this paper. The algorithm meets most of the requirements of security level in recent applications. A system to encrypt speech files recorded with Sound Blaster Card of a personal computer was proposed and simulated successfully using MATLAB® language. Subjective measure and objective measure using segmental spectral signal-to-noise ratio, were used to test the proposed system performance. In these tests residual intelligibility of the encrypted speech and quality of the recovered speech were calculated and assessed. Finally, a hardware implementation of the above cipher system has been proposed using the TMS320-C30. The real time requirements from the speech cipher system have been computed in terms of execution time together with factors affecting such implementation. The results show the capability of the cipher system to be implemented using the DSP device suggested. Furthermore, the results of hardware implementation also show the security of the system is very close to that of the simulated version.


Article
A Suggested Analytical Solution For Laminated Closed Cylindrical Shells Using General Third Shell Theory (G.T.T.)
حل تحليلي مقترح للاسطوانات الطباقية المغلقة باستخدام نظرية الرقائق العامة الثالثة

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Abstract

Transient solutions will be developed for laminated simply supported closed cylindrical shells subjected to a uniform dynamic pressure at the outer surface of the cylinder. These solutions are obtained by using General Third Shell Theory (G.T.T.). Rectangular pulse, triangular pulse, sinusoidal pulse and (ramp-constant) load-time varying functions are studied and the required equilibrium equations are developed. The central deformation and principle stresses are investigated for different cross-ply laminates.

Keywords

Laminate --- Cylindrical --- Shells


Article
The Micro-Slip Damper Stiffness Effect on the Steady-State Characteristics of Turbine Blade
تأثير جساءة الانزلاق الماكروي على خصائص الحالة المستقرة للريش التوربينية

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Abstract

In this paper, a comprehensive study of friction damper stiffness effects on the response characteristics of a typical turbine blade executing steady-state motion, is explored. The damper is modeled as a one-bar microslip type assembled in the intermediate platform attachment of the blade leaving the other attachment of a shroud mass at the blade tip to be free. A discrete lumped mass approach, previously theorized in another paper, is employed to predict the response amplitudes as well as the slip length parameter at any state of the forced frequency including the resonance condition. The analysis covers a practical range of damper stiffness values adapted from relevant studies in this field. The present main outputs show that a magnificent rising of the response occurs with the increase in the stiffness, the characteristic behavior varies appreciably and the resonant amplitudes tend to increase linearly at high levels of damper stiffness, whereas the corresponding frequency and slip length show almost uniform trend. The results can serve very well for design and control purposes in the pre-manufacture stages of the given blade-damper system.

Keywords

Blade --- stiffness


Article
Effect of Rare Earth Oxides (Y2O3, Nd2O3) on Oxidation Kinetics of Al-Li base alloy
تأثير اكاسيد العناصر النادرة ( Nd2O3 و Y2O3 ) على السلوك الكيناتيكي للتأكسد لسبيكة المنيوم –ليثيوم

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Abstract

The oxidation of Al-Li base alloy containing small amounts of rare earth (RE) oxides such as Y2O3 and Nd2O3 particles has been studied at temperatures between 300°Cand 550°C. The lithium is selectively oxidized in Al-Li alloys and the parabolic rate constants for the growth of the resulting oxides layer Li2O, LiAl5O8, Li2CO3 and Li5AlO4 are about an order of magnitude higher than those for growth of oxides on alloy (Al-Li) with RE oxides. Alloys used in this study were prepared by melting and casting in a permanent steel mould under controlled atmosphere. It was found that 0.2%Y2O3 containing alloys possess the lowest oxidation rate and show great improvements in oxidation resistance compared to the base alloy. Oxides found on base alloy are subjected to cracking and spalling during thermal shock at high temperature i.e. 500°Cand 550°C. Identification of oxidation kinetics was carried out by using weight gain measurements while scanning electron microscopy (SEM) and x-ray diffraction analysis were used for microstructural morphologies and phase identification of the oxide scales. The weight gain measurement results suggest that the oxidation kinetic of all studied alloys follows the parabolic law in most experimental tests under the different temperatures except at 300°C oxidation kinetic follows almost a logarithmic rate law.

Keywords

Material --- metal


Article
Turbulent Prandtl Number and its Use in Prediction of Heat Transfer Coefficient for Liquids
استخدام عدد براندتل الاضطرابي لحساب معامل انتقال الحرارة للسوائل

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Abstract

A theoretical study is performed to determine the turbulent Prandtl number (Prt ) for liquids of wide range of molecular Prandtl number (Pr=1 to 600) under turbulent flow conditions of Reynolds number range 10000- 100000 by analysis of experimental momentum and heat transfer data of other authors. A semi empirical correlation for Prt is obtained and employed to predict the heat transfer coefficient for the investigated range of Re and molecular Prandtl number (Pr). Also an expression for momentum eddy diffusivity is developed. The results revealed that the Prt is less than 0.7 and is function of both Re and Pr according to the following relation: Prt=6.374Re-0.238 Pr-0.161 The capability of many previously proposed models of Prt in predicting the heat transfer coefficient is examined. Cebeci [1973] model is found to give good accuracy when used with the momentum eddy diffusivity developed in the present analysis. The thickness of thermal sublayer decreases with Reynolds number and molecular Prandtl number.


Article
Vibration Measurement and Analysis Using Heterodyne Laser Detection
قياس وتحليل الاهتزاز باستخدام طريقة الكشف الهترودايني لليزر

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Abstract

An experimental Michelson interferometer arrangement has been implemented utilizing the principle of laser Doppler vibrometry. He-Ne laser has been used as a coherent light source. The circuit for heterodyne detection has been built to detect and record Doppler signals. Two types of materials have been used as vibrating panel, which are excited by acoustic waves applied from a loudspeaker connected to a function generator. The applied waves were in frequency range of 10- 100Hz. The recorded results of the experimental work demonstrate that the vibration frequency of the panel conforms to the applied frequency when the ratio between the applied and natural frequencies is greater than two (or less than one half).


Article
The Effect Of Increasing Dialysate Flow Rate In Hemodialysis
تأثير زيادة معدل جريان سائل التحليل في عملية الغسل الكلوي الدموي (الديلزة)

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Abstract

Hemodialysis is a technique of removing, or clearing , solutes from the blood and removal of extra fluid from the body, by using dialyzing machine and a dialyzer which is also known as (artificial kidney). The principle of hemodialysis is, primarily, the diffusion of solutes across a semipermeable membrane and ultrafiltration for removal of extra fluid. The purpose of this study is to demonstrate the effect of increasing nominal dialysate flow rate from 500 ml/min to 800 ml/min on the amount of the small solutes (urea) removed from the blood and examine its effect on the amount of dialysis delivered. In this study the in vivo effects of increase in dialysate flow rate on the delivered dose of dialysis studied on 28 maintenance hemodialysis patients. Hemodialysis was performed at dialysate flow rates 500 and 800 ml/min. The patients treated two times per week for 3 hours. The results show increase in urea clearance and dialysis adequacy, and a significant increase in the urea difference between pre- and post-blood urea concentration by increasing dialysate flow rate from 500 to 800 ml/min. It can be concluded that hemodialysis with dialysate flow rate 800 ml/min should be considered in selected patients not achieving adequacy despite extended treatment times and optimized blood flow rate. And increasing nominal dialysate flow rate from 500 ml/min to 800 ml/min alters the mass transfer characteristics of hollow fiber hemodialyzer and results in a larger increase in urea clearance.

Keywords

Biomechanics --- Hemodialysis --- kidney --- dialysate

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