University of Thi-Qar Journal for Engineering Sciences

The axial heat conduction in parallel flow microchannel heat exchanger with rectangular ducts was numerically investigated, for laminar, 3-D, incompressible, and steady state flow of water. The governing equations, continuity, Navier-Stokes equations (momentum equations), and the energy equations for the hot and cold fluids were solved by using SIMPLE algorithm with finite volume method and FORTRAN code to obtain the temperature distribution for the two fluids and the separating wall between them. The results play an important role of the axial heat conduction on the effectiveness in parallel flow microchannel heat exchanger and the factors affecting the axial heat conduction are; Reynolds number Re, thermal conductivity ratio, aspect ratio ? and channel volume. Increasing of Re, , ? and channel volume each separately leads to increase the axial heat conduction and vice versa.

The study is focused on the estimation of rate of soil erosion, using the Universal Soil Loss Equation(USLE), for the embankment of Al-Garma Bridge in Basrah, Iraq. The soil erosion is estimated for the zone of average slope in the study area. The factors considered are rainfall, intensity of rainfall, type of soil, slope length, slope steepness, land use classification, and the existing of soil conservation practices. Detailed analysis of soil samples were done to asses the texture, structure, permeability and organic matter content of the soil samples of the embankment of the Al-Garma Bridge. The average annual erosivity index is obtained as (124.99(MJ. mm/(ha.h))) and the annual average soil erosion rate is estimated as (61.5 t/ha/year).

This paper examines the effects of fusion zone size on failure modes, quasi tension -shear test and energy absorption of resistance spot welds (RSW) of dual phase (DP600) steels. Optical microscopy was used for microstructure investigation. The results showed that some samples failed in pullout failure mode and other samples failed in interfacial failure mode and the failure was located at the base metal. The conventional weld size guidance of 4t0.5 and 5t0.5is not sufficient to produce nugget pullout failure mode for DP600 resistance spot welds.

Mixed convection heat transfer for laminar air flow inside a vented square enclosure with rotation inner cylinder is studied numerically The bottom wall is heated at constant temperature (Th ) while the other walls and the surfaces of the inner cylinder are adiabatic. An external flow enters the square cavity through an opening located down the left vertical wall and exits from an opening located in the upper right wall. The conservation governing equations (continuity, momentum and energy are solved by finite element method using Flex PDE software package. Results of velocity curves, isotherms and average Nusselt number show the effect of the variables: Richardson number (Ri = 0,6,10), Reynolds number (Re = 20, 50, 100 ), Prandtl number (Pr = 0.7), the dimensionless angular velocity (? = 0 –3) and dimensionless radius of rotating cylinder (R= 0 - 0.3) on heat transfer and flow filed. The results show that, the average Nusselt number increases with increasing Ri, Re, R and decreases with increasing ?. The results are compared with other authors in the literature and give a good agreement.

Voice is used in this proposed for the authentication and display information of registered person and find whom is authorized to be access or not. The reason for choosing voice of human because is considered part of biometric system method and is easily being reproduced by human. Besides that, usage of voice gives control system that be effective and convenient to be used. This proposed involve a simple system that consists of voice recognition software and AT89S52 microcontroller with LCD to build up the system. This work is able to recognize the command trained by the user and successfully gives the correct output.

Lightweight foamed concrete exhibits many advantages and excellent features comprising more efficient strength-to-weight ratio in structural elements, high strength, reduced dead load, decrease foundation loads, energy saving, waste consuming, temperature conservation, and noise insulation. This work was prepared to investigate the effect of glass fibers on mechanical properties of structural lightweight foamed concrete (SLFC), Foam agent (organic material) was used to produce SLFC using different mix proportions to obtain structural compressive strength and high workability with slightest fresh density. Five mixes of SLFC with Superplasticizer is experimentally studied, also five mixes without Superplasticizer were tested. The compressive strength, flexural strength, ultrasonic pulse velocity (UPV), workability (flowability) and density were measured. Superplasticizer used in some mixes was 1% by weight of cement. Glass fibers were added in different volume fraction for SLFC and SLFC with superplasticizer. The volume fractions of the glass fibers used are: 0.06, 0.2, 0.4, and 0.6 % total volume. The results of SLFC mixes showed that the increase of glass fibers content can produce foam concrete with enhanced mechanical properties. For all percentages of glass fibers in the mixes it increases in compressive strength and flexural strength. But the increase in compressive strength was 51% for 0.6% glass fibers. Also the flexural strength increased 19.2% for 0.6% glass fibers. The compressive and flexural strength increased with the increase of glass fibers with acceptable range of workability.

A quarter car suspension linear and nonlinear models are considered for the investigation of active vibration control using PID (Proportional-Integral-Derivative) and Fuzzy logic controllers. Simulation of the models using matlab-simulink have been built in this work for passive and active vibration control. The Fuzzy rules and memberships were taken from the literature based on practical experience. A comparison between the linear and nonlinear models using different type of control methods have been carried out. Results shows that the Fuzzy-PID control method is the best among other methods, and the nonlinear model gives better results than the linear model for active control.