Table of content

Journal of Engineering

مجلة الهندسة

ISSN: 17264073
Publisher: Baghdad University
Faculty: Engineering
Language: Arabic and English

This journal is Open Access

About

The Journal Engineering was issued in 1986. It was Stopped from 1990 – 1997 because of the economic blockade. It restarted publication after the fourth scientific engineering conference for it published the papers that were accepted in the conference.
It is a scientific engineering journal refereed by specialized and qualified professors in most of the engineering fields and those Specialists in the issued by the college of Engineering university of Baghdad .It was serenely publibued , but from 2011 it has issued of monthly for the numerous papers submitted to the journal to publish their papers in this scientific journal in addition to some of the Arabs professors because the journal is considered one of the valued journals in the Arabic homelan .
Many professions were the head editor of the journal from its first issue. The first one was prof.dr. Laith Ismail Namiq then prof.dr. Mohammed A.Alawis ,prof.dr.Ali A Al – kilidar prof.dr. Abdul-Ilah Younis and currently Prof.dr.Qais S. Ismail.

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Jadriyah, Baghdad
Iraq
Mobile:
Email: joengbag@uobaghdad.edu.iq

Table of content: 2008 volume:14 issue:3

Article
بعض بدائل الاسكان المفضل في مدينة بغداد

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Abstract

Housing planning is one of the most important subjects in the housing sector studies. It is wide and has many branches.Housing planning according to the cost and social benefit is the solution to prevent the escalating rise in Housing shortage. This fact is combined with which is estimated at more than three million housing unit . And big a reduction in housing construction rate , which lead to increase the housing problem in the country. This matter needs a clear policy from the authorities to accelerate the planning process and to adopt that strategy to solve the housing problem in Iraq. This strategy should adopt the principal of constructing low – cost housing complexes through the construction of multi-stories unit (3-4 stories) , the economic results will be decrease in case of increase the stories to more than (4) stories because of the buildings required to the lift and other services, as a result the cost of the execution and maintenance will be increase, especially when the technical cadres and the technology of the building and the administration were unimproved , in addition to other psychological elements resulting from the highly buildings , there is no domain to talk about it . and of the efficient characteristics which these units have suitable residential densities , active and economic land use and reducing the housing cost to face the big shortage and increased housing demand. The research has conducted a field study of three housing complexes (3-5) stories for the purpose of evaluating this type of housing and the extent if serves the social benefit and complain to design and planning criteria proposed in the General housing plan for Iraq. The research employ (cost & Benefit Analysis) to choose the best alternative from three housing complexes (hay Alsalam , Ziyona , Alsaidia) which serves low cost and best benefit. The research concludes to the importance of depending housing complexes (3-4) stories , and using light weight concrete is emphasized which one of the alternative for traditional building materials as bricks which has many specifications , saving in cost and labor , and reduction in time of construction , and solve of environment cases ,and choose the best alternative from three housing complexes (hay Alsalam , Ziyona , Alsaidia) which serves low cost and best benefit .

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Article
The Concept of Technique Systems in the Notion of Smart Buildings Architecture
مفهوم المنظومات التقنية لفكر عمارة الأبنية الذكية

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Abstract

The magical brilliance between the information abilities and the abilities of controlling the environment and consuming power, which distinguishes the smart buildings. It becomes unavoidable and common things in different fields of architecture like governmental, public, service and productive. Even on the level of planning the city center and urban. That might be attributed in first rank to the vital role of the computer in all aspects of life until the conditioned buildings that are able to fulfill necessary needs of the consumer. It also becomes necessary to provide the conditions of comfort, kindness and entertainment, as regard smart buildings depends in basically in design and the work of the internal, utilitarian and service structure on service systems. They are developed technological techniques that depend in their work on high development and keeping pace with the changes and developments of the information revolution in order to give the fruit of perfect and interactive buildings that offers to the resident comfort environment in order to able to perform their tasks highly.

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Article
Sustainable Environmental Planning & Designing as an Energy Conservation Basics
التخطيط والتصميم البيئي المستدام كأساس للحفاظ على الطاقة

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Abstract

Solar radiation is one of the renewable energy resource that can be used in different fields such as heating, cooling & lighting to employ the double use of passive and active systems' that integrate with the ideal mass grouping, direction, layout & design of building form and its envelope correctly, by the integration of these tools and trends with each others in away that insures energy conservation and lessen the use of fossil fuel in buildings to achieve environmental balancing. In order to explain the point of view for the process of environmental design & sustainable building that include (planning & mass grouping) to work as integrated system to design efficient energy buildings where the site and setting, planning external form, and internal organization as well as storage mechanism, cooling heating and lighting to get best result in order to conclude the relationship between mass grouping, set and layout of the site including all processes that act as bases of environmental design and its relation with thermal comfort and controlling solar (loss & gain) as a goal for internal thermally comfortable environment, visually & biologically, by using renewable energies in residential complexes in hot dry condition.


Article
TREATMENT OF COLLAPSIBILITY OF GYPSEOUS SOIL
معالجة انهيارية التربة الجبسية

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A series of double odometer tests are conducted to study the compressibility and collapse of gypseous soil taken from west of Baghdad governorate. The gypsum content of the soil used is nearly 25%. Four different types of additives are selected to reduce the collapse strain of this soil. These additives are cement, bentonite, calicium chloride and silicagel. An adequate reducing in the compressibility and collapsibility was obtained especially when the cement is used.

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Article
تقويم الجريان غير المشبع للبزل الحر تحت الظروف الحقلية لتربة مزيجة طينية غرينية::ألتنبأ عن الأيصالية المائية غير المشبعة ومقدات المحتوى المائي

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Abstract

Since no in situ studies exist for determining unsaturated hydraulic characteristics of Iraqi soils during internal drainage under no evaporation conditions, a field study was conducted on a silty clay loam soil to determine unsaturated hydraulic conductivity using the Instantaneous Profile Method(IPM) and to solve the one dimensional flow equation under gravity flow theory for obtaining easier method to predicting unsaturated hydraulic conductivity and water content profiles. An 8m * 8m field plot was flooded for forty days and then covered to prevent evaporation from soil surface. Gravimetric samples were augured during 90 days of drainage following flooding as a function of depth. Soil water potentials was estimated from fitting a functional relation to laboratory measured water content and matric potential relations for the studied soil horizons. Unsaturated hydraulic conductivity was calculated according to Darcian flow theory. Unit gradient theory was used to obtain an analytical solutions for the general flow equation according to Lax-Sisson method by utilizing three explicit K(θ) functions. Unsaturated conductivity values for the studied layers ranged from 1.0964 to15.2389 cm.d-1 and from 0.00001 to 0.0004 cm.d-1 after 0.025d and 88.75 d of drainage respectively. A 1:1 relationship between measured and predicted conductivities reveled highly significant r-squared values of 0.918, 0.933, and 0.927 for the three functions respectively. Predicted conductivity values were higher by factors 1.378, 1.418, and 1.296 for the three equations respectively. Same amount of water was drained from studied depths during drainage cycle which resulted in parallel water content profiles. Except at the early drainage time, predicted water contents profile with Lax-Sisson's method matched satisfactorily measured water content profiles. Also 1:1 relationship of zero-intercept between measured and predicted water content values during drainage period produced high r-squared values of 0.960, 0.935, and 0.918 for the three functions respectively. Predicted water content values were higher by a factor 1.008, 1.011, and 1.043 than measured values for the three functions respectively. Results of this study showed that the Lax-Sisson's method was accurate in predicting unsaturated hydraulic conductivity and water content profiles under theory Of gravity drainage flow.

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Article
دراسة ملوثات غازات العادم المنبعثة من سيارات الكازولين في الطرق العراقية

Authors: كريم خلف علي
Pages: 480-502
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Abstract

The work aims to calculate pollutants gases concentration that are emitted from gasoline engine Vehicles exhaust .These concentration are compared with emission limits in other countries. These gases are carbon monoxide (CO), unburned or partially burned hydrocarbons (HC), nitrogen oxides (NOx), lead oxides, particulate matter and soot. The research is carried out on a new and old cars .which are widely used in Iraqi roads .these cars are different in product year , distance travelled and in Exhaust- gas treatment techniques which used. The analysis of exhaust gases carried out by using the electronic exhaust gas analysis system (T156D). Which is maunfactured in Italy and operate with windows system. The results show decrease in concentration of the (CO, HC, NOx, SOOT) emitted from Exhaust gases cars which have low travel distance (new cars model ) these cars use electronic systems to controll on injection , ignition and use exhaust gas pollutant control systems such as early fuel evaporation ( EFE) , exhaust gas recirculation ( EGR) ,catalytic converter , positive crankcase ventilation (PCV ). the results show that there are increases in pollutants concentration emitted from old model which have long work time and not have controller systems on the mixing and ignition systems as well as have lowe maintinance. the results show that ratio of cars which use exhaust gas treatment techniques and satisfy the emits limits is 32% only .but the larger ratio approximately 40% don't satisfy the emits limits.

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Article
استخدام المدخل ألابتكاري في تحليل وحل مشكلات أسلوب الإحالة في مناقصات المشاريع الإنشائية

Authors: صدقي اسماعيل رزوقي
Pages: 503-525
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Abstract

Iraqi Construction Industry faces large challenges especially now adays: these challenges cause many problems in the quality, cost and duration of the projects. One of these challenges is the problems of choosing the appropriate offer, because the lowest one is chosen in spite of the fact that this offer is not the best one. The researcher made a field study for the case of incorrect pricing of contracts through direct interviews with many expertise's. Through the application of innovative approach & brainstorming techniques, a proposed criterion for choosing the suitable offer was suggested depending on many factors as a base for evaluation and tendering of offers. This criterion also evaluated by many senior engineers and assured its suitability

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Article
Porcelanite Rocks as A Dual Filter Media in Water Treatment Plants

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Abstract

Porcelanite rocks were selected to be the dual media with sand in this study to improve the performance of the filtration process in water treatment plants. The work required installing a pilot filtration unit in the location of the filters in one of the water treatment plants, so the experimental work was performed on the same influent water of the filters in the plant (the effluent from the sedimentation tank. The pilot filtration consists of three plastic column filters, working parallel and simultaneously. The first contains 70 cm sand (the same type used in the filters of the plant), the second and third were dual filters (porcelanite with sand) of different depths and sizes using different filtration rates (5, 10, and 15 m/hr). The results showed that the dual filters had better performance than sand filters in turbidity and bacterial removal, less initial head losses and less total head losses at different filtration rates.


Article
Water Quality Indices For Tigris River In Baghdad City

Authors: NAWAR O.A. NASSER --- RAFA H. SH. AL Suhaili
Pages: 2656-2668
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Abstract

Due to the deterioration of water quality within the last few years because of the increase of water consumption and the waste water production and disposal into the river The water quality in both surface and ground water resources was negatively affected .The concept of water quality index is used as a tool for water quality classification in Tigris River within Baghdad City .Twenty two parameters of pollution were selected to measure the water quality indices of Tigris river within Baghdad city .Those parameters were measured during (2000-2004)as average monthly values ,three water treatment plants were selected out of the eight water treatment plants that exist along the river.Al Kharkh water treatment plant to reflect the water quality north of Baghdad ,Al Wathba water treatment plant to reflect water quality at the center and Al Rasheed water treatment plant located south of Baghdad to reflect the water quality at this area .The estimated water quality indices indicated that the river quality deteriorate south of Baghdad and the geological and hydrological conditions played the prime role relative to the agricultural and industrial activities within the catchments on the quality of Tigris river .Furthermore ,due to the continuous decrease of flow and the simultaneous increase in agricultural and industrial development with time ,the river showed a general deterioration in quality while the worst years were 2002,2003 due to the significant decrease in the amount of flow .


Article
Adaptive Video Conference System on A Low Bit Rate Network

Authors: Hamid M. Ali --- Kais Said Ismail --- Fedaa Fahmi Hermez
Pages: 2670 -2682
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Abstract

This paper studies video conference system over low bit rate network. As a result of this study, some ideas are employed to transfer video and audio information through the dial up network with minimum jerky views, discontinuous voice and with a reasonable number of users. A video conference standard, which contains video standard and audio standard, is chosen to build a developed Video Conference System that takes into consideration the monitoring of the network load, by using a special designed sensor, called Network Load Sensor. The NLS is built to sense the network load. Based on the test results, the video resolution and audio compression ratio vary continuously. The system is implemented using visual C++, with using of sockets programming as the interface between clients and the conference server and the use of the Windows Multimedia Platform SDK, which support some audiovisual functions.


Article
Design of Space Time Trellis Coded OFDM

Authors: Ismael Shenan Dshar --- S. M. Abbas
Pages: 2684 -2698
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Abstract

Space Time Trellis Code (STTC) is a technique that can be used to improve the performance of the Orthogonal Frequency Division Multiplexing (OFDM) system over wireless channels by providing both coding gain and diversity gain. STTC is combined from two codes, Trellis Code Modulation (TCM) as an inner code and Space Time Block Code (STBC) as an outer code. TCM which combines the choice of a modulation scheme with that of a convolutional code provides the coding gain, and the other code provides the diversity gain. Simulation is done over flat fading and frequency selective Rayleigh fading channel for Eight Phase Shift Keying (8-PSK) TCM. It found that the best results are obtained for the case of two transmitters and three receivers which have a gain of about 18dB over that without STBC.


Article
INCREASING THE ADSORPTION SURFACE AREA OF ACTIVATED CARBON

Authors: Shahlaa E. Ebrahim --- Abbas H. Sulaymon
Pages: 2700-2717
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Abstract

Experiments were carried out to study the effect of various activated carbon-glass beads weight ratios, influent phenol concentrations, flow rate and bed depth on the performance of fixed bed adsorption column. The equilibrium data and interparticle diffusion coefficients obtained from separate experiments in a batch adsorber were fitted with theoretical model. The effect of adding different weight ratios of an inert solid material to the adsorbent bed in the adsorption process of phenol onto activated carbon was carried out. Adding 5 wt % glass beads to the activated carbon bed reduces the amount of activated carbon by 5% and increases the operating time by 80%.. Increasing the glass beads from 10 wt % and above makes the adsorption process inefficient compared with 0 wt % glass beads. A mathematical model was achieved to describe the mass transfer kinetics in a fixed bed column. The results show that the mathematical model includes external mass transfer and pore diffusion using nonlinear isotherms, provides a good description of the adsorption process for phenol in fixed bed adsorber.


Article
Geotextile and Geomembrane Usage in an Iraqi Sandy Geoenvironment

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The work in this research presents an experimental and a theoretical study to obtain the effect of using a low permeability geosynthetic material on the longitudinal and lateral coefficients of dispersion. This would have its effect on the contaminants migration through an isotropic, homogenous and saturated soil. The first stage of this research involves the study of the geosynthetic material and in calculating the longitudinal and lateral coefficients of dispersion for an Iraqi sandy soil by using an experimental set-up to simulate the processes. To investigate the effect of using a geosynethtic material on the dispersion coefficients, the test was conducted for each velocity that was used in the experimental work and as follows: • without using the geosynethtic material first, and • by using the geosynthetic material as a base and a cover for the soil sample. The second stage of this research is interested in developing a numerical model able to simulate the contaminants dispersion phenomenon. To solve the two-dimensional advection-dispersion equation, a numerical model was derived using the finite element method. This numerical model was verified by comparing it with the analytical solution of one-dimensional dispersion. To study the effect of using a geosynethtic material on the contaminants dispersion through soil, a proposed field problem is tested.

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Article
Sles Surfactant as DraG Reducing Agent within Gasoil Flowing Through Pipelines

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Abstract

Sodium Lauryl Ether Sulfate (SLES) with five different concentrations (from 50 to 100 ppm) were used as drag reducer. This surfactant was studied using gasoil with seven different fluid flow rates (from 1.9 to 4.5 m3/h) and a testing section length of 4 m. Percentage drag reduction (%Dr) was found to increase by increasing the surfactant concentration and Reynolds number. Maximum drag reduction (45.5%) was acheved by using 300 ppm of SLES dissolved in gas oil for flow rate equals to 4.5 m3/h. Friction factor was calculated from the experimental data. For pure solvent; friction factor values lies near or at Blasuis asymptote. While, by producing the surfactants into the flow, the friction factor values were positioned below Blasius asymptote towards Virk maximum drag reduction asymptote. Correlation equation was suggested for surfactant solutions. This correlation shows the friction factor as a function of Reynolds number (Re) and surfactant concentration (C). The results showed good agreement between the observed friction factor values and the predicted ones from the correlation equation.

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Article
A Galvanostatic Polarization Investigation of Steel Corrosion in Alkaline Solutions

Authors: Aprael S. Yaro
Pages: 2752 -2761
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Abstract

The electrochemical behavior of iron and steel in alkaline media is complex,not well understood.It is difficult to determine corrosion rates of steel in high pH solutions by extrapolation of Tafel curves.Polarization resistance (Rp) must be determined in some other way.In this study an attempt was made to find (Rp) values of steel corroding in saturated Ca(OH)2 by anodic currents impressed galvanostatically to the steel from a counter electrode placed together with a reference electrode(I.e. impressed anodic current densities were (10,20,40,and 100µA/Cm2 and duration time was about 25 minutes). It was found that this rapid and non destructive polarization technique yields accepted and reasonable information on corrosion behavior.


Article
Application of Mathematical Drilling Model on Southern Iraqi Oil Fields

Authors: Ali A. Ismael --- Sameera M. Hamad-Allah
Pages: 2763-2784
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Abstract

Minimum-cost well drilling demands the best use of controllable drilling variables for each formation to be drilled. To reach this aim, this study was divided into two main parts: The first part deals with applying a mathematical drilling model to field data of forty wells drilled at three major oil fields (RU, R, and Z). Bourgoyne & Young (1974) drilling model has been modified to take into consideration the combined effect of weight on bit, rotary speed, bit type, bit size, flow rate, drilling fluid density, drilling fluid viscosity, oil content, bit-nozzle size, formation drillability, formation abrasiveness, bit bearing constant, formation hardness, formation compressive strength, differential pressure between mud column pressure and formation pressure, and bit dullness on drilling rate at these fields. The measurements of formation compressive strength have been achieved using 34 core plugs. These plugs were cut and prepared for soft, medium, and hard formations under study. The drilling model was fitted to Field data by using multiple regression analysis technique. The results of analysis gave low standard deviation, high correlation coefficient, and good matching between measured and calculated drilling rate. The validity of modeling process has been verified by applying the proposed drilling model on other wells that have not been included in the main analysis. The second part deals with using the drilling model together with non-linear optimization technique to determine the optimum values of the controllable drilling variables. These variables are: weight on bit, rotary speed, flow rate, drilling fluid density, drilling fluid viscosity, oil content, bit-nozzle size. Using the proposed mathematical drilling model together with the Constrained Rosenbrock optimization technique achieved a marked reduction in drilling cost about 60%, 75%, 80% in soft, medium, and hard formations respectively. The results of optimization were used to construct optimum bit record for the next wells to be drilled. For comparison purpose, this optimum bit record has been used to reduce the drilling cost for well RU263 and saved about 295000 $ in the total cost of this well which is equal to 394176 $.

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Article
Laminar Natural Convection Heat Transfer Between Ducted Parallel Plates

Authors: Hazim S.Hamad --- Yasin K. Salman
Pages: 2786-2803
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Laminar natural convection heat transfer to air flow in a ducted two parallel plates subjected to same constant heat flux has been studied experimentally. In this study a test rig has been designed and constructed to allow studying the effect of plate spacing and plates angle of inclination on the heat transfer process. The study covers three plate spacing 15 mm, 35mm and 60 mm that makes plate aspect ratio (AR) 24, 10.285 and 6, The heat flux implemented in all test runs varies between 55 W/m2 – 340 W/m2 that makes the modified Rayleigh number (Ra) varies from 105 -108 . Experimental results presented as plate temperature distribution, variation of local heat transfer coefficient and the relation between Nu and Ra, reveal for the range of parameters mentioned above, an improvement in heat transfer process as the AR values change from 6 to 24 and the improvement rates is higher for the lower heat flux test (lower Ra). A correlation of the results were made in the form of Nuvr (Gr/AR) in which the effect of duct aspect ratio (AR) has been introduced.

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Article
A Full Missile Homing System Design Based on Proportional Navigation Guidance Law and Electro-Optical Tracking System

Authors: Waleed Kh. Al-Ashtari
Pages: 2806 -2824
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Generally, the homing systems are majorly constructing from three components: the guidance law, the target tracking system, and the missile flight control system. Therefore, in this paper, we construct our homing system from the following components: the proportional navigation guidance law which is considered as the guidance scheme for most homing missile systems, the electro-optical tracking system, and a tail controlled missile. And subsequently complete mathematical derivations and the demand transfer function formulations of all these three components have been introduced. The proposed homing system is capable to pursuit and hit any target just by specifying the required missile flight time. A SIMULINK software program has been built mainly from four subsystems to simulate the operation of this homing system, and the simulation results show clearly the efficient performance of the proposed homing system under any probable disturbance.


Article
Numerical Study of Natural Convection in A Cavity with Wavy Vertical Walls

Authors: SATTAR J. HABEEB
Pages: 2826 -2846
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This paper describes a numerical study of natural convection heat transfer and fluid flow characteristics inside a cavity with wavy vertical walls. The bottom wall is heated by spatially varying temperature and other three walls are kept at cooled temperature. Governing equation was discretized using the finite volume-method with staggered variables arrangement in curvilinear coordinates. Two geometrical configurations were used in this study for symmetrical and unsymmetrical wavy vertical walls (total of 132 cases) for range of Ra=100 to 106 and fixed Prandtl number (0.71). The effects of the wave geometry, wave amplitude, number of undulation, and Rayliegh number on flow behavior, thermal field, local Nusselt number and Nusselt number ratio (NNR) factor have been studied. Streamline, velocity vector, and isothermal contour are used to present the corresponding flow and thermal field inside the cavity. The Results show that the enhanced of heat transfer rate seems to depend on geometrical configuration.


Article
Prediction of Erosion Effect due to Cavitation on AL-Mosul Power plant Turbine

Authors: Laith W. Ismail --- Jafar M. Hassan
Pages: 2848 -2861
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In the field of hydraulic power plant, the cavitation is responsible of sever erosion which requires periodic unit shutdowns for inspection and repairs. Al-Mosul hydroelectric power plant is chosen as model in this study. Computer programs are developed by using the velocity gradient method to analyze the flow in the runner blades of the turbine (Francis Turbine) to calculate the available cavitation and compared with the critical cavitation. The erosion of the runner material (erosion rate, weight of lost material and mean depth of erosion) is also calculated to limit the operation hours of the power plant. The presented work shows that the cavitation appears on the underside of the turbine (Francis Turbine) blades in the trailing edge at distance of 82% from the leading edge due to decrease in pressure, flow separation and interference zone. This causes erosion depth of about 4 mm for the first four years of operation which represents about 17% of the blade thickness of the trailing edge. It is found that the operation hours of Al-Mosul power plant should not exceed 24000 operation hour. A good agreement is found between the prototype data obtained from the computer program analysis and experimental visualization shown in the literature and theoretical solution.

Keywords

Erosion --- Cavitation --- Turbine.


Article
Behaviour of Cross - Ply Laminated Hybrid Composite Plates with an Inclined Crack Subjected to A uniform Temperature Rise

Authors: Majid H. Faidh-Allah
Pages: 2863-2872
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Thermal buckling analysis of symmetric and antisymmetric cross-ply laminated hybrid composite plates with an inclined crack sub¬jected to a uniform temperature rise are presented in this paper. The first-order shear deformation theory in conjunction with variational energy method is employed in the mathematical formulation. The eight-node Lagrangian finite element technique is used for obtaining the thermal buckling temperatures of hybrid composite laminates. The effects of crack size and lay-up sequences on the thermal buckling temperatures for symmetric and a antisymmetric plates are investigated. The results are shown in graphical form for various boundary conditions. Finally , from this paper, the following main results have been found from which the buckling temperature is affected the larger crack length more than the small crack length, together with other result that the buckling temperature of the plate for every perforation angle is to increase while crack length is increasing


Article
The Harmonic Currents Generated by 6-Pulse , AC|DC Converter With The Use Of AC Voltage Regulator

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In this paper , a theoretical and experimental analysis of harmonic currents generated by 6-pulse , ac|dc converter with the use of ac voltage regulator is presented. The theoretical analysis is simulated using Fourier series analysis and Fast Fourier Transform ( FFT ) algorithm . The simulated analysis is validated with experimental results from 3-phase , 6-pulse , bridge converter rated at 4.2 Kw and connected to the 400 V , 50 Hz , ac power supply through a 3-phase , ac voltage regulator . The influence of dc load inductance on the ac harmonic current amplitudes is also evaluated.


Article
A Fuzzy Recognition Model For Arabic Handwritten Alphabet

Authors: Sami Kadhim Hasan Ar-Ramahi
Pages: 2891-2900
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A fuzzy recognition model for some handwritten Arabic alphabet is designed. This fuzzy model could be envisaged as an algorithm which is structured over two concepts. First; the handwritten character variation is modeled by the fuzziness of the feature vector's elements. Second; the notion of entropy is fuzzily modified to extract the amount of information in the elements within the feature vector so as to speed up the recognition process. Consequently, a fuzzy recognition graph of the optimum paths decision tree is designed for the handwritten Arabic alphabet character's recognition.


Article
Influence of Temperature Fluctuation on Thermophilic Anaerobic Digestion of Municipal Organic Waste

Authors: Mohanad Jasim Mohammed
Pages: 2901-2911
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A laboratory-scale experiment was carried out to estimate the influence of temperature fluctuation on thermophilic anaerobic digestion of municipal organic waste (MOW). Heating failure was simulated by decreasing temperature gradually from 55 °C to 20 °C gradually 2 h time need for temperature decrease and recovery. Under conditions of 8.0 g/ (L•d) and 15 d respectively for MOW load and retention time. Following results were found: (1) biogas production almost stopped and VFA (Volatile Fatty Acid) accumulated rapidly when accompanied by pH decrease. (2) With low temperature (20°C) duration of 1, 5, 12 and 24 h, the thermophilic anaerobic digestion system reproduce methane after temperature fluctuation of 3, 11, 56 and 72 h. (3) The bacteria was influenced by the temperature fluctuation where it decayed, hydrolysis, acidification was high as the low temperature interval lasted. (4) The thermophilic microorganisms were highly flexible to temperature fluctuation.


Article
Mathematical Simulation of Unsteady Flow through Hollow Fiber Membrane

Authors: Raghad Samir Mahmood --- Riyadh Zuhair Al Zubaidy
Pages: 2912 -2928
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Water flowing through hollow fiber membrane comprises two types of flow each having its own hydraulic characteristics. The first is the flow inside the fiber channel, and the second is the flow through the fiber porous wall. Water flow through hollow fiber membrane, HFM, is unsteady nonuniform flow due to the accumulation of rejected material on the fiber surface causing a change in the hydraulic resistance along the fiber length with time. Under these conditions, a mathematical model was developed to simulate water flow through hollow fiber membrane based upon the equations governing the flow inside the fiber channel and through the fiber wall, equations governing conditions imposed by flow boundaries, and implicit finite difference technique for solving partial differential equations. The model was verified by using published laboratory experimental data. A very good agreement was obtained between the measured and predicted flowrate values under the same conditions. The mathematical model was applied to three types of commercially available fiber modules to investigate variation of flux, the transmembrane pressure, the thickness of the rejected materials along the fiber length, the flowrate, and the effect of the pot length on the fiber hydraulic performance. It was found there is considerable variation in the hydraulic performance of the three types of fiber. Therefore, the mathematical model provides a tool to work on finding the optimal design of the hollow fiber membrane.

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