AL-Rafidain Engineering Journal (AREJ)

The current research is a result of the study in fractal dimension of antenna application, but it becomes in out of line. The objective of study was to full-fill the space of near field region by a cumulative electromagnetic pixel at focal point; as a result the space was full-fill by multi-pixels known as coherent focuses. Coherently between the rays reaching focal point leads to focusing. One of the studied results “Focusing Feasibility in Fractal Array Antennas”; is the relation between the quadratic distances between the elements of focused array and the appearance of coherent focal points. The simulation, analysis, and proven include a deal with the essential mathematical relations which leads to conclude a number of new forms likes, definite focal region, definite coherent focal region, predicate of co-herent focal positions.

This research studied the effect of liquids on the Engineering properties of the Limestone rocks. The liquids used were: crude oil from Ain Zala, crude oil from Kirkuk, natural ground Water. The Limestone used was brought from Eski Mosul situated at 45 Km north west of Mosul. Both the compressive and tensile tests were conducted on the Limestone rock specimens in the dry and saturated case using;Uniaxial, Triaxial Compression and Bending tests. The tests showed that saturation with any one of the liquids lead to a decrease of both compressive and tensile strength. The greatest decrease occurred when ground water was used to saturate the specimens, and it was also noted that the effect of saturation gave greater percentage of decrease on the compressive than the tensile strength. The study also showed that liquids lead to decrease in cohesion ( c ) and the Friction angle (Φ) obtained from triaxial test. The liquids used for saturation didn't have clear effect on the type and mode of failure on all specimens tested .

This paper is intended to study the influence of the grain boundaries on the electronic and optoelectronic behavior of Au/P-Si Schottky diode. These diodes were fabricated by evaporation of gold layers onto polycrystalline silicon wafers using vacuum evaporation technique. The current-voltage characteristics at different grains boundary and temperatures, spectral response were investigated. It is found that the Schottky barrier height for Au/P-Si diode obtained form I-V and spectral response characteristics are depends mainly on the surface grain boundary density and state density.

This study aimed to treat the wastewater of several hospitals (Jamhory Hospital , Ibn-Sina Hospital , Batool Hospital , Hazem Al-Hafez Hospital) in Mosul city, by using the method of coagulation and flocculation and by using the Jar_Test as a laboratory scale. Alum and Lime were used as coagulants in wastewater treatment. The efficiency had been calculated by the following characteristics :- ( Chemical Oxygen Demand (COD), Total Solids Matter (T.S), Nitrate (NO3) , Phosphate (PO4) , (pH) , Electrical Conductivity (Ec) , Chloride , Turbidity ) . At the optimum dose of alum (80) mg/l removal efficiencies were (66%) for (COD), (73%) for (T.S) and (87%) for Turbidity . the Nitrate removal efficiency was (65%) at the optimum dose (60) mg/l .The optimum dose of Lime was (400) mg/l for removal (COD) , (T.S) and Nitrate , the removal efficiency of (COD) was ( 58%) , (67%) for (T.S) and (50%) for Nitrate . The Alum was better than Lime in removal efficiencies of pollutants from hospitals wastewater. The heavy metals removal efficiency at the optimum doses were ranged from ( 89.28-97.8)%

This research is intended to improve the performance of ZnO/n-Si solar cells. The structures were fabricated using thermal evaporation techniques. The indium dopant at suitable heat treatment is used to enhance the electrical characteristics of ZnO layer resulting in reducing atmospheric condition to change the stiochiometry of ZnO layer. The electric properties of the fabricated samples are dependent on many parameters such as annealing temperature, ZnO layer thickness, Indium layer thickness and temperature. The indium layer were deposited at different thickness (10-30) nm during the fabrication of the ZnO/n-Si solar cells. The resultant samples has been studied and the results obtained show an improvement in the efficiency of 0.4% compared with the standard ZnO/n-Si solar cell

Plain-carbon steels are considered to be the most widely used materials in engineering and industrial applications. In this study wide range of carbon steels are used in the most common corrosion environments which are salt water and drinking water. The weight loss method is used, then corrosion rate is found to correlate with carbon percentage of steels. The results indicate good correlation which are related to the microstructure where higher pearlite show higher corrosion rate and pearlitic steel represents the maximum corrosion rate. This is found in both environments used where higher corrosion rate is the characteristic of salt water. It is also found that the longer exposure time the lower corrosion rate while weight loss is still continuing.

In recent years, the scale of power systems has been expanding, and with that expansion smooth power operation is becoming increasingly important. One of the solutions is to realize a practical high speed, highly reliable exciter system that is suitable for stable operation of a power system. In this work, a model of a static excitation system of an alternator connected to a network via a transformer have been built using MATLAB-SIMULINK PSB. The parameters of the machine has been obtained from Mosul dam power station taking into account saturation effects. A PI controller is used to control the output reactive power of the synchronous generator for both pure DC excitation and static excitation systems. A method based on step response has been proposed and verified for tuning the parameters of the controller. In order to validate the simulated results of the system with AVR, the results have been compared with practical results of Mosul dam and a good agreement has been realized. However, in large generating units, undesirable oscillations in the active power and speed result as a side effect of the AVR control or due to outside disturbances.

Many Architectural studies deals with concept of adaptation in architecture with different ways various according to the trend of each study, this show’s the importance of studying the concept of adaptation in the architectural field in general. This research tray to focus on the concept of the adaptation of type in architecture because it’s important in the generation of the new architectural models and the reiteration of the typological chain. Reviewing previous studies focusing on this concept show’s the absent of a theoretical frame witch separate a specific items of the process of adaptation of the architectural types through different natural and cultural effects. Thus, the problem her was the absence of a specific imagination of the procedures and mechanisms for achieving adaptation of the architectural types through different natural and cultural effects. To solve this problem, the researcher adopted the approach of building a theoretical framework for the adaptation of type in architecture, Witch includes the items: The target of adaptation, the kind of effect which cues adaptation, the procedures and mechanisms to achieve adaptation. The achievement of these items depended on the help of the previous studies

This paper deals with the design and simulation of an optical gigabit Ethernet using OPTSIM 3.6 packet software. The main aim of the proposed design is to build a MAN optical network using one-gigabit Ethernet technique, and what are the necessary requirements to build these networks. As a case study, all states center are connected as Star – Bus topology using layer2 and layer3 optical switches. In addition, in this paper one-gigabit optical transmitter and receiver are designed to work as a node in the network topology. Further more, the benefits of using L- Band wavelength for transmission take in consider the linear and non-linear effects on fiber optic is presented.

The current research tackles the study of analogy depended on in designing products of students of academic architectural study as it is one of the important designing strategies in the process of architectural designing because it is closely related with the stage of synthesis and the derivations of architectural concepts within the designing process. The research discusses the importance of this concept in order to explore the particular problem represented by the unclarity of analogy role in the designing products of students of academic architectural study over their different grades. Therefore the problem of the research was crystallized and its objective and methodology were identified by studying analogy by two axes, included the analogy and the designer, the analogy and designing process, reaching the determination the theoretical framework, that involved four main items, which are; the item of analogy cause, analogy sources, the paradigm of dealing with the analogy source and the nature of the designing element relevant to analogy, firstly. And then applying the theoretical framework on selected projects of students of academic architectural study in the second, third and fourth grades in Mosul University, secondly, in order to explore the change of analogy application paradigms adopted by the students in those grades, thirdly. The results showed that the differences in students’ trends throughout different academic grades led to the emergence of similar differences in the nature of practicing analogy in those grades.

Automatic segmentation of audio streams according to speaker identities, environmental and channel conditions has become an important preprocessing step for speech processing, speaker recognition and audio mining. This paper presents an automatic speech segmentation system where the performance of the probabilistic neural network (PNN)(which is the main part of the system) is examined and then enhanced in the area of segmentation of conversational speech. The results show that a percentage false segmentation (PFS) of 18% can be achieved. PFS is dropped to 6.1% enhancing the system. The experiments were carried out on a dataset created by concatenating speakers from the TIMIT database.

In this paper,we introduce a new model, of long-period fiber grating, by taking the value of ambient refractive index greater than the refractive cladding index, where the difference between them must equal(≈0.2).The results show the change in power attenuation coefficient, where it increases with the increase in refractive ambient index. The power attenuation coefficient shift shows a dramatic change of a sharp increase from 0.00 dB to 0.03788 dB

In this paper, path planning for cylindrical manipulator of 4-DOF is studied. Another view point is presented for using so called ‘artificial potential fields’ which is used as the base of searching for new and safe points in the manipulator’s workspace among static obstacles. Three vectors are used for safe manipulator navigation. The first vector is determined between the end-effector and the goal points and it is used to attract the end-effector to the goal point. While the second and third vectors are computed from points defined on the obstacle and the end-effector. These two vectors are used to repel the end-effector and the arm from the boundaries of the obstacles. In this work, the obstacles are suggested to have a cylindrical shape with different sizes. Displacement detections between the manipulator (its end-effector and arm) and the obstacles are used as sensors for collisions impending. A random movement is suggested for joint two to avoid contacting between the arm and obstacles. At the off – line path mode, all path points are determined by the presented method and some of them are updated, if an arm collision is detected, then joint variables are calculated at each point. In real mode, these joint variables are fed to a simple real control system to make the manipulator tracks the found path. The method gives a safe path for undertaken manipulator. An experimental work is also presented

Among the important proposed water-dependent crop production function is that of Jensen's. The application of this model requires knowledge of power parameters that reflect the sensitivity of each growth stage to water deficit. However, the values of these parameters are available only for a limited number of crops. Among the production models to which sensitivity parameters are quite available is that of Doorenbos and Al-Kassam. The objective of this study is to relate these two models. The results of the analysis showed that the yield response parameters for maize crop in Jensen model were found to be (0.1, 0.22, 2.5, 0.3, 0.1) respectively. Also, a polynomial equation is developed to relate predicted yield response parameters in Jensen model to yield response factors, valid for all growth stages, in Doorenbos and Al-Kassam model. A comparison was made between the predicted parameters with those obtained from previous works indicating acceptable agreement.

An experimental test rig was designed and manufactured to investigate the performance of a heat pipe(HP). The heat pipe consists of a stainless steel pipe lined with a three-layer stainless steel mesh wick. The evaporator section of the heat pipe was surrounded by three heaters representing the heat source. The condenser was jacketed with galvanized cylinder to accommodate the cooling water flow. The entire HP was insulated. Different affecting parameters were investigated experimentally in this study including the power input the filling charge of the working fluid(water) represented by a volumetric ratio with respect to evaporator volume and the inclination angle with a horizontal line. All tests were carried out at a pressure around the atmospheric pressure during steady state conditions. The experimental results showed that the conductivity was about (2060) times that of the solid piece of the stainless steel (the material of the HP).A comparison between the present work results with empirical and theoretical correlations of other researchers showed a good agreement