Table of content

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: 2015 volume:18 issue:2

Article
The Effect of Cylinder Head Face Cutting on The Diesel Engine Performance &Exhaust Emission
دراسة تأثير قطع وجه رأس الاسطوانات على أداء وانبعاثات محرك ديزل رباعي الاشواط

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Abstract

The aim of this study is to know the effect of remove layer from head cylinder thickness on engine performance and exhaust emission. In this experiment used four stroke four cylinder diesel engine connect to the hydraulic dynameters , The experiment was conducted at a fixed engine speed of 1500 RPM and variety load with two type of cylinder head M0(original head cylinder thickness and for this type the Compression ratio equal 18) and M1 (remove 1mm from head cylinder thickness and the Compression ratio will be increase and become Cr=19) and.brake specific fuel consumption , brake thermal efficiency and brake power were examined , M1 produce better engine output such as: brake thermal efficiency increase by 0.87%,Bp increase by 0.50%, CO2 increased by 18% while the NOx increased around 1.37% in the other hand found brake specific fuel consumption decrease by 0.75% and monoxide carbon decrease by 33% when compared with cylinder head type M0.

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Article
The function and formal dynamic of the typical stories in high buildings
الوظيفة و الدينامية الشكلية للطوابق المتكررة في الابنية العالية

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Abstract

Sees that the essence of the formation and the high building production based to the function, which in turn affected and changed levels by change the shape of building at any moment of the vertical and horizontal extending, and most of this, the high buildings has seen formative developments, especially in multi floors, structure, capacity of spaces, and functions for those floors that recognized by the first beginnings of high buildings forms. These developments mostly been grader to produce sculptural forms make them different from traditional high buildings, that this formality change effect in the level of function and their types or at the level of the comparison between the building floors itself and extended over to the building performance and their urban integration. Thus crystallize the research problem in the lack of studies which dealt the efficiency of high buildings formation, which in turn formed the intercalation phenomena on the cities, without any common features between them and the fabric of the city, and with the horizontal towers. The create dynamic formalities creates rearrange the four varieties function (usability - structural - Environmental - Iconic), thus creating a functional dynamic that rearranges the levels of dominance function on those changing floors , so the search was divided into three sections are: 1 - Function and their types. 2 - Performing and dynamic formal and urban integration. 3 - practical study of a global project (Norman Foster), and three proposed architectural projects for architecture students /AL-Nahrain University / 2013. Thus the research adopted on two hypotheses, the first: that the four function are mainly in the form of high buildings production, and the second: that the formal change of the building floors involves a functional change, according to the previous classifications. Research benefit lies in: - Strengthening go towards the high buildings that have strong function and form, thought full in terms of mutual changes. - Evaluation the projects for proposed high buildings. - Call to raise the performing efficiency and urban integration.

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Article
A modified Suction-controlled Triaxial Equipment
جهاز مطور لفحص القص الثلاثي المحاور باستخدام تقنية ضغط الامتصاص

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The paper presents a modified equipment for triaxial testing of soil samples under unsaturated as well as saturated conditions. The equipment is capable of performing various types of hydro-mechanical loading including wetting and drying stress paths under constant or varying net stresses. The suction is controlled/ measured by using axis translation technique. Initial investigation on the performance of the testing system after appropriate calibrations had been conducted indicated good level of accuracy in measuring various soil properties.


Article
Irrigation Scheduling as a Tool to Improve the Water Use Efficiency for Cherries Plants
جدولة الري أداة لتحسين كفاءة المياه المستخدمة لنباتات الكرز

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Abstract

Methods for scheduling irrigation are important aspects of good crop and plant management. Irrigation scheduling process is concerned with quantity and date of irrigation. In this paper Time Domain Reflectometer (TDR) is used as a soil moisture tool to measure the trend of the soil moisture in the root zone of Cherries in Michigan State/ United State of America for three years of measurements. The study analyzes the effect of irrigation process by using trickle system on the variation and trends of the soil moisture. Furthermore, the study compares the quantities of the applied water with the soil water content to get the soil water depletion and the actual crop evapotranspiration. The results show that there is no fixed and clear irrigation schedule within the years of the study (2009, 2010 and 2011). Over irrigation in some months the soil becomes in saturated conditions. On other hands, in some months and during the years of study, the soil moisture deficit be more than the allowable depletion and sometimes close to limit of permanent wilting point, and this is due to apply a deficit irrigation, knowing that the root depth of this study is 1.22 meter only, which means that the crop may be extract the water by roots that are deeper than 1.22 meter. Knowing that the saving water and energy is very important and also system evaluation and its maintenance are required.


Article
A GIs Based Weight of Evidence for Prediction Urban Growth of Baghdad City by Using Remote Sensing Data
تنبؤ النمو الحضري لمدينة بغداد بأستخدام بيانات الآستشعار عن بعد مسندا بطريقة أوزان الاثبات

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The rapid growth of Baghdad city has an adverse effect on the environment; therefore, it is crucial to have a well-concerted plan for urban expansion. This paper presents the problem of urban growth in Baghdad city; hence, it is develop a methodology that combines remote sensing data and GIS with Weight of evidence to estimate the occurrence spatial distribution of urban extent. Accordingly, the required data for the proposed model building were identified by using satellite imagery of Landsat MSS/TM/ETM for years, 1976, 1990 and 2000 respectively. The satellite imagery is utilized for geometric correction, supervised and unsupervised classification, accuracy assessment, derivation of change detection and urban growth modeling. Three factors were considered in model building of urban growth in weight of evidence: environmental, social and economical factors. Geodatabase was digitized in ArcGIS and combined to develop statistical models relating land use to population density, distance from the center of the city, distance from highway, river and slope of study area. The work emphasizes spatial relationships between various geographic, land-use, and demographic variables to predict future urban extent. Based on the urban growth model in GIS, results show: the urban area in Baghdad is increased rapidly; the result of the work shows a rapid growth in built-up land between 1976 and 1990 from 100 km2 to 380 km2 and from 452 km2 in 2000 to 610 km2 in 2015. Finally, the case study demonstrated that GIS based weight of evidence is recognized to be used as a useful tool for prediction of urban growth by considering saving of money, time and effort.


Article
Sand Dunes Stabilization Using Silica Gel and Cement kiln Dust

Authors: Majeed Mattar Rammal --- Ahmed Ameen Jubair
Pages: 179-191
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Abstract

This research includes the study of adding some available cheap and Local materials to Sand Dunes (SD) such as, Silica Gel (SG) and Cement kiln Dust (CKD) which are used as stabilizers and sand improvement . The Laboratory tests out on (June 2013 to November 2013). Some Physical and chemical characteristics of(SD),(SG) and (CKD) were obtained, also Grain Size Distribution(GSD) and chemical composition were obtained. The program was divided into two stages the first one includes preparing four mixtures three of them Silica gel were added to tape water to make solution (2.5%,5% and 7.5%) , then adding to the sand dunes, which is denoted by (m1, m2 and m3) respectively , the fourth mixture represent reference( sand dunes) ,these mixtures aging for (7, 14 and 28 ) days. Pure sand dunes and these three mixtures were tested to determine the wind velocity effects on drifting sand, shear strength force, cohesion and penetration .The second stage includes determining the best results of three previous mixtures, which called typical mixture, and (2.5%,5% and 7.5%) of CKD were added to the typical mixture, which is denoted by (m41, m42 and m43) respectively , these mixtures aging- curing period- for (7, 14 and 28 ) days. Generally, this study showed significant improvement in the performance of sand dunes by using Silica Gel and Cement Kiln Dust, which means that, they can be used as stabilizer and soil improvement as economic and available materials.


Article
Laboratory Study of the Effect of Reinforcement Strips (Cfrp) on the Ductility and Confinement of Reinforced Concrete Columns
دراسة مختبريه لتأثير صفائح الكربون البوليمر المسلحة على ليونة والحجز الأعمدة الخرسانية المسلحة

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Abstract

The issue of repairand reinforcement of structures is one of the major branches of civil engineering. In this direction, the reinforcement of the pressure members, especially the reinforced concrete columns by reinforced polymer sheetsis considered as one of the conventional methods in reinforcing these members. By confining the pressure member and preventing lateral expansion resulting from the Poisson’s effect,the FRP sheetbrings about an increase in compression strength and ductility. In this laboratory research, the effects of different methods of reinforcing concrete columns by CFRP sheets including the effect of the width of reinforcing sheets on ductility and stress-strain behavior of the concrete columns in the presence of internal reinforcement of the column were studied. The steel reinforcement of column includes evaluation of the effect of longitudinal and transverse steel bars, number of transverse bar, and also development bar of longitudinal reinforcement on the rate of confinement. The results of this research show that by suitable arrangement of CFRP reinforcing sheets, the confinement in the reinforced concrete columns can be created appropriately.


Article
Modeling of Continuous Stirred Tank Reactor based on Artificial Neural Network
نموذج لخزان مفاعل مستمر الإثارة مبني على أساس الشبكة العصبية الذكية

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This paper presents the dynamic model identification algorithm of the continuous stirred tank reactor (CSTR) using a multi-layer perceptron (MLP) neural network topology. The neural network approach for (CSTR) dynamic modeling is trained by using a particle swarm optimization (PSO) technique as a simple and fast training unsupervised algorithm. Polywog wavelet activation function is used in the structure of MLP neural network. The identification algorithm given in this paper has been proved to be reasonable and precise via Matlab simulation results in terms of fast, stable and minimum number of fitness evaluation for the CSTR modeling.


Article
Sliding Mode Controller for Electromechanical System with Chattering Attenuation
مسيطر ذو شكل إنزلاقي للأنظمة الكهروميكانيكية مع تخفيف للإرتجاج

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Abstract

Electromechanical systems (EMS) may be considered as devices transforming electrical into mechanical energy. Every system that belongs to the electromechanical class can be decomposed in an electrical (ES) and a mechanical subsystem (MS). The motion control systems can be quite complicated because many different factors have to be considered in the design of electromechanical systems. These factors can be summarized as the nonlinearity, non-smoothness in its model, the uncertainty in system model parameters and non-satisfying matching condition. In this paper a new sliding mode control design approach for the EMS is proposed without neglecting the inductance in the electrical part or approximating the non-smooth perturbation. The first step in the proposed controller design consists of transforming the ES to a low pass filter (LPF) and then (the second step) designing a sliding mode controller (SMC) to the MS that will reject system model uncertainty and the effect of non-smooth disturbances. With a suitable selected LPF time constant, the SMC which controls the MS is nearly the equivalent control and as a result the chattering is attenuated greater than that in the case of classical SMC which designed by ignoring the electrical subsystem and also with a smaller control effort. The simulation results, of applying the proposed sliding mode control to an electromechanical system, show its superiority compared with classical SMC designed in two effective SMC features beside forcing the state to follow the desired position where chattering amplitude is greatly reduced with a significant reduction in control action value (approximately equal to third the required input voltage with the classical SMC).


Article
Chaotic Multiple Access System Based on Orthogonal Chaotic Vector of Lorenz System
نظام الوصول المتعدد الفوضوي المستند على متجه فوضوي متعامد نوع لورينز

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Chaos phenomenon is capable of generating chaotic sequences with low cross-correlation, which can be useful for spreading the direct sequence code division multiple access (DS-CDMA) system. In this paper, a chaotic multiple access communication system based on Orthogonal Chaotic Vector (OCV) generated from Lorenz system has been proposed. The simulation results show that the performance of the proposed system is almost the same regardless of the number of users in Additive White Gaussian noise AWGN channel. The results also show that at bit-error-rate of 10-3, the proposed system has achieved gains of 6 dB and 11 dB in signal-to-noise ratio over traditional DS-CDMA based on Walsh-Hadamard sequence in AWGN and Rayleigh fading channels, respectively.


Article
Control of Hydraulic Transients in the Water Piping System in Badra – Pumping Station No. 5
التحكم بتأثيرات المطرقة المائية في منظومة أنابيب الماء لمحطة ضخ بدرة رقم 5

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In this paper, the surge tank utilization method was used to prevent the water hammer. The study was conducted on a practical problem at pipelines and pumping station of Badra – pumping station No. 5, which is possessed to Iraqi General Company for Execution and Irrigation. For this purpose, Surge2012 transient analysis software was used to achieve the best design and checking parameters. The study recommends installing 2x14m3 closed surge tanks near to lifting station. The outlet/inlet nozzle has to be of 300 mm diameter. The initial air volume must be 5 m3 for each one. All these parameters must be achieved to maintain a positive and negative pressure waves in pipe network system within accepted values.


Article
Application of Response Surface Methodology for Modelling and Optimization of Hot Corrosion Rate of Nimonic 75 Coated by Ce-doped Aluminizing-Titanizing
تطبيق منهجية سطح الإستجابة لنمذجة و تحديد العوامل المثلى لمعدل التآكل الساخن في سبيكة نيمونك 75 المطلية بطريقة الألمنة-تيتنة المحورة بالسيريوم

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Abstract

Response surface methodology (RSM) was used to determine the optimum conditions (wt.% of Na2SO4, %wt. of V2O5, and Temperature ) that give the minimum hot corrosion rate (Kp) (g2 cm-4 s-1) for Nimonic75 coated by Ce-doped Aluminizing- titanizing . Experiments were designed according to central composite design in response surface methodology with these three factors using MINITAB 16 and MATLAB 2014a Software. The variation of hot corrosion rate (Kp) with hot corrosion parameters was mathematically modeled using response surface methodology. The optimum conditions obtained were 40 wt.% of Na2SO4, 40 %wt. of V2O5, and 900oC . This resulted in ( Kp=1.430987×10-10 g2 cm-4 s-1 ) as obtained from the predicted model , which fitted well with the laboratory verification result ( Kp=1.4311×10-10 g2 cm-4 s-1 ) . This was supported by the high value of coefficient of determination (R2=99.81%) of the Predicted model . The high correlation coefficient (R2= 98.991%) between the model and the experimental data show that the model was able to predict the hot corrosion rate from hot corrosion conditions.


Article
Heat Treatment Effect on Anodizing Corrosion Resistance of Low Carbon Steel
تأثير المعاملات الحرارية على مقاومة التآكل للصلب الكاربوني المنخفض المؤنود

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This work involves studying heat treatment effect on anodized low carbon steel using electrochemical measurements. Heat treatments of low carbon steel before anodizing were applied by anodizing at different temperatures of 650, 900, and1000°C for one hour. Anodizing process was used for non-annealed and annealed low carbon steel at the above temperatures in KOH solution. The electrochemical behavior of low carbon steel, anodized low carbon steel, and anodized annealing low carbon steel at the above temperatures in 3.5 wt% NaCl solution using potentiostat device. Corrosion rates for the above conditions were measured. The corrosion rates measured results indicate an improvement in corrosion resistance of anodized annealing low carbon steel. Surface characterization of anodic film on low carbon steel was examined anodic film on low carbon steel using Atomic force microscopy (AFM) and optical microscopy used to examine the specimens before and after corrosion test. the practical results indicate the best conditions to obtain higher corrosion resistance are for anodized low carbon steel annealed the steel before anodizing at 1000 °C.


Article
Heat Transfer Enhancement of Flat Plate Solar Collectors for Water Heating in Iraq Climatic Conditions
تحسين انتقال الحرارة في خلية طاقة شمسية مسطحة لتسخين المياه في الظروف المناخية في العراق

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This work presents an experimental and numerical study to investigate the heat transfer enhancement of flat plat collector (FPC) using three types of twisted tapes (single twisted tape (ST), double twisted tape (DT) and mixed twisted tape (SDT)) which are compared with plain tube with twist ratios (TR=2). The study are considered under fully developed turbulent flow with solar radiation heat gain are changing with time. The designed FPC consists of four pipes with 1.25cm in diameter and 1mm thick are placed above the plate to act as a heat removal fluid passage ways. The system consists of two collectors, each one has (40cm x 160cm x 15cm) and connected to two tanks, each one is 20 liters. The amount of heat gain from solar radiation depends on many effective parameters are used; type of twisted tape are using, type of collectors plate metal (aluminum or copper), value of Reynolds number, amount of sun rays available at the site, number of glass covers and orientation of the collectors with respect to the south direction. From the experimental results was obtained which are demonstrate that the DT are more efficient than ST and SDT, since the heat transfer enhancement which increases the output temperature of the working fluid. The experimental study also show that the temperature of outlet water from mixed twisted tape collector is higher than the other type of plain tube collector by 10°C. The outlet water temperature of collector made from cupper is more than the collector made of aluminum about 6°C. The outlet water temperature from collector which has Reynolds number of 5000 less than 5°C for copper collector and less than 4°C for aluminum collector from the other with Re number is 10000. Increasing of the temperature of the outlet water in the collector which has two glass cover is about 4°C from one glass cover. The numerical analysis was based on finite volume numerical techniques to solve the governing partial differential equations in three dimensions, using ANSYS FLUENT commercial CFD software, to study the effect of Reynolds number and twisted tape types on the heat transfer enhancement and friction factor. The comparison between the experimental and numerical results shows a high agreement, and the maximum error was 8.3% occurred with mixed twisted tape.

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Article
Spray pyrolysis of Low Carbon Steel by Polymer Matrix Composite
الرش بالانحلال الحراري للفولاذ المنخفض الكربون بواسطة مادة مركبة ذات اساس بوليمر طلاء

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In this research study the effect of spray pyrolysis that coating low carbon steel with epoxy reduced corrosion rate by (89.4%), while coated low carbon steel with epoxy composite reinforcement at 2%wt of (Al,TiO2, and Zn) was result the corrosion rate of coated specimens with epoxy composites reinforcement (Al, TiO2, and Zn) are lower than coated specimens with epoxy by (73.42%,91.75%,97.9%) respectively. The weight loss of low carbon steel coated with epoxy at90ºand 300 impingement angles are lower than those of uncoated specimens of low carbon steel by (51.06%,43.2%) respectively ,while the weight loss at90ºand 30º of coated specimens with epoxy composites reinforcement (Al,TiO2) lower than coated specimens with epoxy by (34.78%,17.39%)and (47.61%,23.80%) respectively. The weight loss of erosion characteristics at90ºand 300 of coated specimens with epoxy composites reinforced (Zn) are higher than coated specimens with epoxy by (34.78 %, 28.57%) respectively. The wettability determine by measuring the contact angle that are small than 70º signifies hydrophilic surfaces have high surface energies and good wettability. The adhesive strength of coated specimens with epoxy composite has low adhesive strength than that in coated specimens with. The used (AFM) to showed surface morphology and surface roughness of coated specimens with epoxy and epoxy composites .The Pore Size measurement of specimens surfaces coating by (SEM), signifies each type of coated specimens with epoxy composites decreased than with epoxy.


Article
Natural Frequencies of Multi-Irregular Span Beams under Elastic Supports by Modal Analysis Method
الترددات الطبيعية للعتبات الغير منتظمة الفضوة المتعدده تحت اسناد مرن باستخدام التحليل الشكلي

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Evaluating the natural frequencies of multi- span beams with elastic supports play a major role in vibration designing and optimizing of many structures such as bridges, railways ,pipes and so on The continuity of the boundary conditions ,state space and numerical methods are normally used to investigate the vibration characteristics of such structures .Unfortunately ,such methods lead to high size matrix in dealing with the boundary value problem as the number of spans increase. In the present work, the problem is solved analytically by using Modal Analysis techniques in which the continuous system is discreteized to finite degree of freedoms in terms of the generalized coordinates A proper shape function are employed for describing the system dynamical behavior and satisfying the boundary conditions .In the present method the size of the resulting Eigen matrix depends on the number of mode chosen regardless of the number of spans. With this method wide variety of support configurations can be treated. The validly and convergence of the present method for calculating the natural frequencies is carefully checked by comparing with the exact values for two-span beams with different boundary conditions . It is found that using only (5) modes for the assumed solution gives only 2% error for two span simply supported and free ends beam , however for clamped ends the error is 8% .The present method is further checked by comparing with the Finite Element method the results show good agreements where the error is not increases 1% .The results of the natural frequencies of up to (10) equal and unequal spans beams under different boundary conditions and support stiffness are presented .The results showed that the natural frequencies can be highly controlled by proper choosing of the structure parameters and support stiffness.


Article
Study on Control of CSTR Using Intelligent Strategies
دراسه سيطرة المفاعل الكيمياوي المستمر CSTR بأستخدام أستراتيجيات ذكيه

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A non linearity, interaction and complexity in modeling lead to a great difficulties in CSTR control system, this paper interested in CSTR control using PID, fuzzy logic and intelligent control strategies. Water flow rate and ethyl acetate were selected as manipulated variables while sodium acetate and reactor temperature as controlled variables. Firstly the system identification was conducted and the results show that the multi input multi output system can be represented by the following matrix The compare among the strategies show preference of fuzzy control.


Article
Study the Effect of Electrospinning Device Room Temperature on Electro-spun PVA Nano-fibers
دراسة تأثير درجة حرارة حجرة جهاز الغزل الكهربائي على ألياف بولي ﭭينيل الكحول المغزولة كهربائياً

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This research focuses on studying the effect of electrospinning device room temperature on PVA nano-fibers diameter made by electrospinning device depositing on rotating drum. In this research, the preparation of nano-non woven fabrics by electro-spun polymer solution of poly vinyl alcohol using distilled water as solvent in temperature range [15-35]C° was achieved. The relative humidity 40%, polymer solution concentration 14% wt., voltage 22KV, tip-to-collector distance 10 Cm. The results of the five scanned samples by scanning electron microscope (SEM) indicated that: by increasing room temperature the diameter of nano-fibers decreased. Also it is important to mention that the range of room temperature shouldn't be exceeded in order not to close the orifice of the needle because of the evaporation of the droplet solvent changing into solid polymer.


Article
Fabrication and Investigation of Nanostructured Monolayer Porous Silicon (PSi) Based for Silicon Solar Cell Applications
التحقق من الخصائص الكهروضوئية للسلكون المسامي

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Fabrication of PSi is generated successfully depending upon photo-electrochemical etching process. The purpose is to differentiate the characterization of the PSi monolayer based on c-silicon solar cell compared to the bulk silicon alone. The surface of ordinary p-n solar cell has been reconstructed on the n-type region of (100) orientation in order to enhance the conversion efficiency. The process relied on varying the etching time with fixed current density. The other process conditions were kept constant, for instance, HF concentration, current density, temperature,etc. The role of different laser types and powers illuminated the n-region has been realized. In particular, the blue laser (473nm of two powers 50 and 100mW) appears to be the most operative wavelength to obtain the optimum efficiency and pore sizes as well as the etching rate. The samples were tested and characterized by the (I-V). Measurement and analyzed by SEM, PL and AFM tests. The obtained solar cell efficiency was in the range of 11% compared to the typical solar cell efficiency which was (3.34%).


Article
Antibacterial Silver Nanoparticles produced by Nd:YAG Laser
دقائق الفضة النانوية المضادة للبكتريا المحضرة بليزر Nd: YAG

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Q-switched Nd-YAG laser of wavelengths (1060, 532 and 322 nm) with energy in the range 200 to 1000 mJ and 1 Hz repetition rate was employed to synthesis silver nanoparticles using pulse laser ablation in liquid. Effect of laser wavelength has been studied for the fundamental, second and third harmonic generation. The experimental UV-Vis absorbance data were fitted with theoretical Mie-Gans model. It is found that the smaller silver nanoparticle of 12 nm capable to terminate both Staphylococcus and Streptococcus bacteria.


Article
Photoacoustic Application for Gas Detection
التقنية الضوئية الصوتية للكشف عن الغازات

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Laser photo acoustic spectroscopy is a technique to detect and measure trace gas using infrared laser radiation. This technology is based on the generation of acoustic wave in a gas excited by a modulated laser beam at a wavelength corresponding to the absorption line of the gas species at the resonance frequency of the acoustic resonator, and detecting this sound wave using a sensitive microphone. This work presents the experimental procedure of laser photoacoustic gas detection at different levels of concentration using Freon-12 as the sample gas. The experimental work has been accomplished by fabricating a photoacoustic cell which consists of an acoustic resonator of 50mm length and 4mm diameter. The resonator is terminated by two gas buffers and partial transmission windows for laser wavelength of 10.6µm. A sensitive microphone has been fixed in midpoint between the mirrors. A CO2 laser of effective power levels 0.7-2W has been used to induce the acoustic wave. The analysis of experimental data has been accomplished using matlab software.


Article
Process Optimization of Biosorption Hg(II), Cu(II) and Ni(II) Ions onto Dead Anaerobic Biomass using a Two-Level Full Factorial Design and Response Surface Methodology, Batch Systems
عملية تحسين الامتزازا الحيوي لايونات الزئبق ،النحاس والنيكل باستخدام الكتلة اللاهوائية الميتة باستخدام اثنين من مستوى كامل المضروب وتصميم ومنهجية الاستجابة السطحية، نظام الدفعة

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Dead anaerobic biomass prepared from drying bed wastewater treatment plant were used as adsorbents for the biosorption studies of mercury, copper and nickel ions from synthetic wastewater. The main and interactive effects on uptake of Hg(II), Cu(II) and Ni(II) in this study are investigated through the model equations designed by a two-level full factorial design. Experiments designed by central composite design were carried out and the process response was modeled. Heavy metals removal efficiency and uptake have sequence order Hg(II) > Cu(II) > Ni(II) under tested conditions, Hg(II) offers the strongest component that able to displace Cu(II) and Ni(II) from their sites, while Ni(II) ions was the weakest adsorbed component. Best removal efficiencies were 96.2, 90.3 and 82.4 when temperature 400C, pH 6, initial metal ion concentration 10 mg/l, biomass loading 6 g/l, contact time 180 min, and 200 rpm for Hg(II), Cu(II) and Ni(II) respectively. The results predicted using factorial regression model showed high values of regression coefficients (R2) 0.945 indicating good agreement with experimental data. The main biosorption mechanisms were complexation and physical adsorption onto natural active functional groups. It is observed that biosorption of these metals was a surface process.


Article
Dynamic Analysis of the Gait Cycle for Normal and Abnormal Subjects
التحليل الحركي خلال دورة المشي للاشخاص السليمين والمرضى

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Identification of pathological gait is the most direct application of gait analysis. The purpose of the study is to investigate the dynamics of human walking over a complete gait cycle. Level-walking experiments were performed by two-dimensional (2D) motion analysis using a digital video camera (Sony, 25 Hz) and two force plates. Kinematic data were obtained from the trajectories of 7 reflective markers using SkillSpector software (ver. 1.2.4). MATLAB software (ver. 8.1) has been adopted in this work to obtain Pedotti diagram and for inverse dynamics computations. Digital low pass Butterworth filter with zero phase-shift and cut-off frequency of 4.5 Hz was used. Joints' angular displacement, forces, and moments were obtained during gait cycle. The study was made on fourteen healthy volunteers (10 males and 4 females); a male with cerebral palsy, and an old female underwent unilateral knee arthroplasty. These data can be used as standard measures in pathology studies, as input to theoretical joint models, and as input to mechanical joint simulators.

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