Tikrit Journal of Engineering Sciences

This work is concerned with magnetic and torque analysis of BLDCM and with development of a method of designing BLDCM that have symmetric winding on the rotor .make significant contribution to the rotor inductance position difficult. It is also show that the prediction detent torque can be extremely sensitive to the permanent magnet by altering magnet arc width. Finally, simple lumped models that allow one to predict motor performance and characteristics as a function of main dimension, magnet residual flux density and phase current are developed. These models are used as a basis for an approach to designing BLDCM.

Absorption of carbon dioxide into carbonate solution (Na2CO3) with PAM (non-Newtonian fluid) has been performed in a countercurrent packed column (0.075m i.d. ×1.25 m height) packed with glass Raschig rings (1×1cm) to a depth of 1m. The influence of liquid flow rate, gas flow rate, liquid temperature, and polyacrylamind (PAM) concentration on the absorption rate, overall mass transfer coefficient and the reaction kinetics regime are studied at constant carbonate concentration and atmospheric pressure. The results show that the absorption rate and overall mass transfer coefficient increases with increasing liquid flow rate and temperature. The mass transfer coefficient decreases with increasing gas flow rate while the absorption rate of carbon dioxide is virtually independent of gas flow rate. This indicates that carbon dioxide absorption is liquid film controlled. Increasing PAM concentration results of reduction of absorption rate and overall mass transfer coefficient. The reaction kinetics between carbon dioxide and carbonate solution with PAM was obtained as a pseudo first order reaction (Hatta number, Ha >>1).

The tendons arrangement effects on the response of reinforced concrete frame experiencing blast loads is investigated in this paper. The structure is modeled using nonlinear finite elements employing a bilinear hysteretic model. So that elements are used so that yielding of the structures could be accurately modeled and captured. The frame is analyzed using a non-linear, elastic-plastic finite element program written in code MATLAB. Six tendon architectures were investigated. A single tendon was placed between different floors and its effects investigated. From the obtained results, the ideal case which causes a reduction in the maximum displacement and the amount of permanent deflection without increase in the maximum structural shear forces greatly is obtained.

In optimal design concept, the geometric dimensions of a channel cross-section are determined in a manner to minimize the total construction costs. The Direct search optimization method by using MATALAB is used to solve the resulting channel optimization models for a specified flow rate, roughness coefficient and longitudinal slope. The developed optimization models are applied to design the round bottomed triangle channel and trapezoidal channels to convey a given design flow considering various design scenarios However, it also can be extended to other shapes of channels. This method optimizes the total construction cost by minimizing the cross-sectional area and wetted perimeter per unit length of the channel. In the present study, it is shown that for all values of side slope, the total construction cost in the round bottomed triangle cross-section are less than those of trapezoidal cross-section for the same values of discharge. This indicates that less excavation and a lining are involved and therefore implies that the round bottomed triangle cross-section is more economical than trapezoidal cross-section.

This paper studies simulation and evaluation of Ethernet Passive Optical Network (EPON) system, IEEE802.3ah based OPTISM 3.6 simulation program. The simulation program is used in this paper to build a typical ethernet passive optical network, and to evaluate the network performance when using the (1580, 1625) nm wavelength instead of (1310, 1490) nm that used in Optical Line Terminal (OLT) and Optical Network Units (ONU’s) in system architecture of Ethernet passive optical network at different bit rate and different fiber optic length. The results showed enhancement in network performance by increase the number of nodes (subscribers) connected to the network, increase the transmission distance, reduces the received power and reduces the Bit Error Rate (BER).

A theoretical approach is used to analyze single pile and pile in group under lateral loading using two programs. The first one used the finite element method for single pile depending on plain strain condition while the second one used the characteristic load method for pile in group. Horizontal displacement for pile in group is measured while both horizontal displacement and shear stress for single pile are measured. A comparison between the results of horizontal displacement for both single pile and pile in group with the actual practical values are produced and shows a good agreement.

Aerodynamic modeling of ballistic missile in pitch plane is performed and the open-loop transfer function related to the jet deflector angle as input and pitch rate, normal acceleration as output has been derived with certain acceptable assumptions. For typical values of ballistic missile parameters such as mass, velocity, altitude, moment of inertia, thrust, moment and lift coefficient show that, the step time response and frequency response of the missile is unstable. The steady state gain, damping ratio and undraped natural frequency depend on the missile parameters. To stabilize the missile a lead compensator must be added to the forward loop.

Basra crude oil was hydro treated in trickle–bed reactor using cobalt – molybdenum alumina as a Catalyst. The reaction range temperatures was598 – 648 k, while LHSV was 0.7 – 2 hr-1. The pressure and H2/Oil for all experiments keep constant at 3Mpa and 300 L/L respectively. Desulphurization and demutualization kinetics were studied and found that the kinetics of sculpture removal is of first – order, and the kinetic of vanadium and nickel removal is of second – order. Activation energy were calculated and their value are 24.03, 745.86, 63.90 KJ / mole, respectively for sculpture, vanadium, and nickel.

This research included the study of the effect of reinforced glass fibers on fatigue properties for composite materials. Polyester resin is used as connective material(matrix) in two types of glass fibers for reinforced. The first type is regular glass fibers (woven roving) with the directional(0-90), the second is glass fibers with the random direction. The first type is the panels with regular reinforced (0-90), and with number of layer (1,2). The second type is the panels with random reinforced and with number of layers (1,2). The results and the laboratory examinations for the samples reinforce with fibers have manifested (0-90) that there is a decrease in the number of cycles to the fatigue limit when the number of reinforce layers have increased . And an elasticity of this type of samples are decreased by increasing the number of reinforced layers with fiber .We find the random reinforced number of fatigue cycles for the samples with two layers of random reinforced are decreased more than the samples with one layer of random reinforced .

The aim of the present study is to analyze the thermal performance of a building which is of 600 m3 size. The building is built in three different models. In the first model, walls are built with brick. In the second model, a layer of foam (Polystyrene) of 4 cm thickness has been used as an insulation layer inside walls and on the roof. In the third model, walls are constructed from two parts separated by air gap of 8 cm wide; moreover a secondary roof is added to this model. A Qbasic program is prepared to simulate the required mathematical equations in finite difference method and the weather conditions data of Baghdad city at January, 1994. The results of the simulation showed that the ratio of the saved energy by the second and third models with respect to the first model are 29.96%, and 35.40% respectively.