Tikrit Journal of Engineering Sciences

Heat transfer process involved in the autoclave curing of fiber-reinforced thermosetting composites is investigated numerically. A model for the prediction of the temperature and the extent of the reaction across the laminate thickness during curing process in the autoclave of unsaturated polyester based composite has been developed. The governing equation for one dimensional heat transfer, and accounting for the heat generation due to the exothermic cure reaction in the composites had been used. It was found that the temperature at the central of the laminate increases up to the external imposed temperature, because of the thermal conductivity of the resin and fiber. The heat generated by the exothermic reaction of the resin is not adequately removed; the increase in the temperature at the center increases the resins rate reaction, which in turn generates more heat.

The present paper examines and tests an alternative method to control and redirect electric power flow through certain paths (transmission lines). The control and redirecting of power flow is achieved through the use of phase shift transformers PSTs. An algorithm is presented which searches for a proper phase shift angle introduced by a PST at any given location. The proposed method is based on modelling the PST and the power system employing Newton-Raphson load flow approach. Finally, the installation of series of PSTs on the interconnected power systems aims at mitigating uncontrolled parallel flows and unbalanced sharing of power among transmission lines. The obtained results showed the effectiveness of the proposed method in sharing and controlling the electrical power flow among different interties of the 5-bus network on which the study applied.

This paper investigates the saturable transformer from modeling and control point of view. After implementing the Simulink model of the three phase transformer simulation of a three phase, two-winding transformer is used to examine the transformer under two operating conditions. The first is the secondary terminal short circuited and the second is the secondary terminals connected to a non-unity power factor load to verify the results obtained with those predicted from any analysis using the equivalent circuit. The graphical user interface is used for modeling transformer parameters, obtaining the results, check the stability of the control system, the settling time, the Bode plot, Nyquist and Nicols chart finally recording all currents, voltages and phase shift between them in the steady state condition, initial values of states variables for the nonlinear circuit parameters.

In order to characterize ground water quality in Zaweta district / Dohuk governorate, eight wells are selected to represent their water quality. Monthly samples are collected from the wells for the period from October 2005 to April 2006. The samples are tested for conductivity, total dissolved solids, pH, total hardness, chloride, alkalinity and nitrate according to the standard methods. The results of statistical analysis showed significant difference among the wells water quality in the measured parameters. Ground water quality of Zaweta district has high dissolved ions due to the nature of studied area rocks. Total dissolved solids of more than 1000 mg/l made the wells Gre-Qassroka, Kora and Swaratoka need to be treated to make taste palatable. Additionally high electrical conductivity and TDS made Zaweta ground water have a slight to moderate restriction to crop growth. The high alkalinity of Zaweta ground water indicated stabilized pH. The water quality of all the wells is found excessively hard. The nitrate concentration of Zaweta ground water ranged between 0.19-42.4 mg/l below the guidelines for WHO and the maximum nitrate concentration is recorded in Kora well.

In this research, a bench-scale filter is designed and constructed in order to compare the performance of different media namely, sand, crushed marble stone and crushed red brick. The filters are operated under various operating conditions such as filter depth, raw water turbidity, pretreatment, effective size and uniformity coefficient. These filters are operated under conventional and direct filtration modes with different doses of alum. Statistical methods had been used to determine the best media using Duncan multiple range test. The result showed the superiority of crushed red brick media in the removal of turbidity and total bacteria. The results also indicated that filters operated under direct filtration mode show better performance than that operated under conventional filtration mode. The pH of treated water show slight increase for the two modes of filtration.

In electric motors, electrical energy is transformed to mechanical energy or vice versa. Electrical energy has to be transformed from a stationary component into moving one, which is done by copper commentator in sliding contact with graphite brushes. This study includes a technical method to prepare metal – graphite composite brushes. The prepared brushes are tested and found to have mechanical and electrical properties agree with standards.

Water is the most important natural resource in this century. Irrigation is the largest consumptive use of water, so we must increase the efficiency of irrigation and estimated agricultural water requirements accurately. In this research, a computer model using Visual Basic v.6.0 is formulated. The model simulates the complicated on-farm “ crop-soil-climate” phenomena to estimate the reference crop evapotranspiration, adjustment for daily, every ten days and monthly. Estimating Single and dual crop coefficient is made to plan the agricultural water requirements with different cropping patterns for Irrigation Associations. The model is setup and operated by using data from Iraq and other countries. Results analysis show that the model can effectively and efficiently estimate the agricultural water requirements.

This paper investigates a power swing effect on a distance protection relay performance installed on (HV/EHV) transmission line as well as power system stability. A conventional distance relay can’t properly operate under transient stability conditions; therefore, it cause mol-operation, and it will adversely impact on its trip signals. To overcome this problem, the Out Of Step (OOS) relay has modeled and simulated to joint with distance relay to supervise and control on its trip signals response. The setting characteristics technique of the OOS based on concentric polygons scheme method to detect power swing under transient stability situation. This study ia a modeling and simulating using (Maltab\ Simulink) software. A Two relays had been performed and tested with two equivalents network connected to ends. The results of this study showed an activity and reliability of this way to control the distance relay response under a transient stability conditions and it indicated the possibility to find out faults which may occur at period of power swing.

The Sequencing Batch Reactor (SBR) method is used for treating samples of waste water taken from hospitals in Mosul. Many run periods are used (6-24) hours for 6 months. It is found that the organics and suspended solids removal increase with increasing the period of run, it is in the range ( 96-82 )% and ( 100-95 )% respectively, while the pH values are nearly neutral (7.05 to 7.5). BOD5 and SS concentrations of the effluent are within the limits of Iraqi standards, 40:30 mg/l respectively. Hence, SBR method could be used for treating hospitals, small factories and some residential sectors waste waters.

An experimental study on natural convection heat transfer from two parallel horizontal cylinders in horizontal cylindrical enclosure was carried out under condition of constant surfaces temperature for two cylinders and cylindrical enclosure. The study included the effect of Rayleigh number, rotation angle that represent the confined angle between the passing horizontal plane in cylindrical enclosure center and passing line in two cylinders centers, and the spaces between two cylinders on their heat loss ability. An experimental set-up was used for this purpose which consist water container, test section which is formed of plastic cylinder that represent the cylindrical enclosure, and two heating elements which are formed of two copper cylinders with (19 mm) in diameters heated internally by electrical sources that represents transfer and heat loss elements through this set-up. The experiments were done at the range of Rayleigh number between (), cylinders rotation angle at (), and spacing ratio at (). The study showed that the ability of heat loss from two cylinders is a function of Rayleigh number, cylinders rotation angle, and the spaces between them. This ability is increased by increasing of Rayleigh number and it was showed that this ability reaches maximum value at the first cylinder () and minimum value at the second cylinder () at spacing ratio (S/D=3) and rotation angle () for the first and () for the second cylinder respectively. The effective variables on natural convection heat transfer from the above two cylinders are related by two correlating equations, each one explains dimensionless relation of heat transfer from each cylinder that represented by Nusselt number against Rayleigh number, rotation angle, and the spacing ratio between two cylinders.