Al-Khwarizmi Engineering Journal

This paper presents the motion programming and control of omni-directional mobile robot through the process of building and programming a small robotic platform with secondary design criteria of modularity and simplified control. This is accomplished by combining the positive aspects of several different robotics platform ideas. The platform is shaped like an equilateral triangle with a servo motor, sensors, and omni-wheel, controlled by a PIC microcontroller.
In this work the kinematics, inverse kinematics and dynamic module for the platform is derived. Two search algorithms (the wall-following search and the “most-open-area” search) is designed, tested, and analyzed experimentally

An experimental study was carried out to improve the surface roughness quality of the stainless steel 420 using magnetic abrasive finishing method (MAF). Four independent operation parameters were studied (working gap, coil current, feed rate, and table stroke), and their effects on the MAF process were introduced. A rotating coil electromagnet was designed and implemented to use with plane surfaces. The magnetic abrasive powder used was formed from 33%Fe and 67% Quartz of (250µm mesh size). The lubricant type SAE 20W was used as a binder for the powder contents. Taguchi method was used for designing the experiments and the optimal values of the selected parameters were found. An empirical equation representing the relation between surface roughness with operation parameters have been achieved.

Equilibrium and rate of mixing of free flowing solid materials are found using gas fluidized bed. The solid materials were sand (size 0.7 mm), sugar (size0.7 mm) and 15% cast iron used as a tracer. The fluidizing gas was air with velocity ranged from 0.45-0.65 m/s while the mixing time was up to 10 minutes. The mixing index for each experiment was calculated by averaging the results of 10 samples taken from different radial and axial positions in fluidized QVF column 150 mm ID and 900 mm height.
The experimental results were used in solving a mathematical model of mixing rate and mixing index at an equilibrium proposed by Rose. The results show that mixing index increases with increasing air velocity and mixing time until it reaches an optimum value then decrease to an equilibrium value. The results also show the dependency of the mixing index on the particle size of the tracer component.
The statistical analysis of the obtained theoretical mixing index versus the experimental mixing index shows that the standard error is 0.92 % (about 1 %) with the correlation coefficient of 0.9857 and the total residual of 0.002 for the ninth observation of the mixing index (theoretical versus experimental) over 95% confidence level.

The ability of Cr (VI) removal from aqueous solution using date palm fibers (leef) was investigated .The effects of pH, contact time, sorbets concentration and initial metal ions concentration on the biosorption were investigated.
The residual concentration of Cr (VI) in solution was determined colorimetrically using spectrophotometer at wave length 540 nm .The biosorption was pH-dependent, the optimum pH was 7 and adsorption isotherms obtained fitted well with Langmuir isotherms .The Langmuir equation obtained was Ce/Cs = 79.99 Ce-77.39, the correlation factor was 0.908.These results indicate that date palm fibers (leef) has a potential effect for the uptake of Cr (VI) from industrial waste water.

Computer models are used in the study of electrocardiography to provide insight into physiological phenomena that are difficult to measure in the lab or in a clinical environment.
The electrocardiogram is an important tool for the clinician in that it changes characteristically in a number of pathological conditions. Many illnesses can be detected by this measurement. By simulating the electrical activity of the heart one obtains a quantitative relationship between the electrocardiogram and different anomalies.
Because of the inhomogeneous fibrous structure of the heart and the irregular geometries of the body, finite element method is used for studying the electrical properties of the heart.
This work describes the implementation of the Conjugate Gradient iterative method for the solution of large linear equation systems resulting from the finite element method. A diagonal Jacobi preconditioner is used in order to accelerate the convergence. Gaussian elimination is also implemented and compared with the Precondition Conjugate Gradient (PCG) method and with the iterative method. Different types of matrix storage schemes are implemented such as the Compressed Sparse Row (CSR) to achieve better performance. In order to demonstrate the validity of the finite element analysis, the technique is adopted to solve Laplace's equation that describes the electrical activity of the human body with Dirichlet and Neumann boundary conditions. An automatic mesh generator is built using C++ programming language. Initially a complete finite element program is built to solve Laplace's equation. The same accuracy is obtained using these methods. The results show that the CSR format reduces computation time compared to the order format. The PCG method is better for the solution of large linear system (sparse matrices) than the Gaussian Elimination and back substitution method, while Gaussian elimination is better than iterative method.

In developing countries, individual students and researchers are not able to afford the high price of the subscription to the international publishers, like JSTOR, ELSEVIER,…; therefore the governments and/or universities of those countries aim to purchase one global subscription to the international publishers to provide their educational resources at a cheaper price, or even freely, to all students and researchers of those institutions. For realizing this concept, we must build a system that sits between the publishers and the users (students or researchers) and act as a gatekeeper and a director of information: this system must register its users and must have an adequate security to ensure that only the affiliated students are able to access its services. It also needs to have security and trust mechanisms built-in for commercial partners to accept their connections. This paper describes the work done on the design and implementation of the IVL (Iraqi Virtual Library).

The problem in the design of a cam is the analyzing of the mechanisms and dynamic forces that effect on the family of parametric polynomials for describing the motion curve. In present method, two ways have been taken for optimization of the cam size, first the high dynamic loading (such that impact and elastic stress waves propagation) from marine machine tool which translate by the roller follower to the cam surface and varies with time causes large contact loads and second it must include the factors of kinematics features including the acceleration, velocity, boundary condition and the unsymmetrical curvature of the cam profile for the motion curve.
In the theoretical solution the unidirectional impact stress waves with the Mushkelishvilis inverse of the singular integral equation for contact stress have been used for analytical solution and a numerical solution have bean solved using F.E.M (ANSYS 10) for stress analysis in a cam surface at condition of rise-dwell-return (R-D-R) motion of the follower, also to compare the analytical and numerical results that have been used different pressure angles in the rise and return of the motion curves in unsymmetrical cam profile for optimum design.

A series of experiments have been taken out to test the validity of the effect of Aluminum hydrate on its interaction with Aluminum during sintering of aluminum metal matrix. The approach has been shown to be valid and several compositions have been fabricated. The alumina hydrate particle size and the amount of alumina hydrate in the composites are also shown to have an influence on the extent of densification.
The densities for all sintered specimens were measured. It was found that density increases as compaction pressure increases, the density decreases as particles size increases. At 400 MPa there is an optimum particles size which is (90-125) µm to reach maximum density and the density decreases as volume fraction increases from 2% to 20%.
The microstructure enhances as compaction pressure increases, agglomeration of alumina hydrate particles increases with increasing of volume fraction and cavities increases especially at low compaction pressure more than at high compaction pressure.
The mechanical properties (compression test and Vickers hardness) of sintered specimens compacted at 100 MPa accomplished for three volume fractions 2%, 10% and 20% and three particles size (45-90) µm, (90-125) µm and (125-150) µm. Young's modulus in compression decreases as volume fraction increases. Also it decreases as particles size increases and Vickers hardness decreases as volume fraction increases. Also decreases as particles size increases.