Journal of Engineering

The dispersion of pollutants in the Diyala River was studied using a one-dimensional Finite difference technique (implicit method) to solve the simplified dispersion equation. The model begins at Diyala barrage and extends to the confluence of the Tigris-Diyala rivers, covering a length of 203 km. The results were verified by comparison with the analytical solution for different time increments. The model was calibrated on 31/11/1998 using measured data (discharge, velocity, cross-sectional area, total dissolved solids (TDS), chloride (Cl⁻), and sulfate (SO₄²⁻)) concentrations on the same day, and the results indicated a good agreement between the computed and measured data. The model was verified on 13/12/98, 27/12/98, 10/1/99, 25/1/99, indicating the accuracy of the applied model to simulate conservative salts (TDS, Cl⁻, SO₄²⁻) in the river.

In most of the group technology approaches the formulation and simplification of data entry has been ignored. This has lead to difficulties and complexity for the end-user of the group technology, especially in the cases where the number of machines and components are large and complex. The way the data are inputted are in the form of a 0-1 matrix, which is quite difficult, troublesome, and error creation is possible in their entry, even with double-checking in their input. Also for output results, as it is given in the form of the 0-1 matrix and left to the end-user to interpret instead of giving the result in a such a way that it could be used by the end-user directly. In this paper, a systematic formulation of data input and output is introduced so as to make easier for the users to enter their data as simple as possible and with minimum error occurrence, especially in the cases where there are considerable number of machines and components to be dealt with. And also use the results directly without any further interpretation. The proposed system for data entry and output interpretation has been applied and then implemented in two different companies with easiness and appreciation of end-user in terms of data input, minimum corrections, simple and direct usage of outputs without further interpretation.

This paper discusses the purpose of determining the standard parameters for overlap spot welding tests based on thickness and overlap distances. It is noted that the overlap joint is the most convenient method for spot and riveting joints. The analysis of riveted and welded connections involves many indeterminate factors, making an exact solution impossible. However, by making certain simplifying assumptions, the study aims to explain the behavior of the junction to the applied load and the rotational angle, which depends on the yield strength of the base metal and the maximum load of the welded joint. Classical fracture theory, Misses, and bending beam theory were used. The failure of the test sample is defined as "fracture initiation," corresponding to the peak load. Two theories with simple assumptions were applied to reach the final formula suitable for lap welded joints, and the mechanism of fracture and initiation of crack were examined.

In this study a proposed design for reinforced concrete barriers in industrial units is presented. The barriers are deemed to mitigate the hazards of internal explosions to protect the surroundings. The Technical Manual (TM5-1300) for fortified structures recommends the use of lacing reinforcement barrier walls when the plastic rotation exceeds a specified limit. Such reinforcement is essential in shear design but it needs special skill and additional cost. To avoid using lacing reinforcement, walls of grillage system is proposed in this study to reduce the plastic rotation of panels. The panels are designed to respond plastically, while the grillage members respond elastically. This is advantageous from recruiting point of view since only the blast-damaged panels may be repaired.

Results have shown that the (SDOF) analysis method as recommended by the (TM5-1300) (D.C., 1992) gives an upper bound solution as compared with the (F.E) method. Cubicles of ribbed walls show higher blast resistance and exhibit smaller plastic support rotation of panels than that of flat-sided walls. The minimum thickness required to avoid using lacing reinforcement have been obtained for different cases of grillage arrangements and charge weights.

This paper discusses the purpose of determining the standard parameters for overlap spot welding tests based on thickness and overlap distances. It is noted that the overlap joint is the most convenient method for spot and riveting joints. The analysis of riveted and welded connections involves many indeterminate factors, making an exact solution impossible. However, by making certain simplifying assumptions, the study aims to explain the behavior of the junction to the applied load and the rotational angle, which depends on the yield strength of the base metal and the maximum load of the welded joint. Classical fracture theory, Misses, and bending beam theory were used. The failure of the test sample is defined as "fracture initiation," corresponding to the peak load. Two theories with simple assumptions were applied to reach the final formula suitable for lap welded joints, and the mechanism of fracture and initiation of crack were examined.

Nowadays, large and small manufacturing companies own several numerically controlled (NC) lathe machines. They are finding that NC/CNC machines can make dramatic savings possible. Certain aspects of NC/CNC shop operations require a higher skilled operator level than conventional methods, so the need to develop a computerized technology to support the adoption of these machines and get the maximum benefits is highly recommended. The present work aims to develop such a system that stands over the most modern available technologies to support this task. The system database is used to organize the factory data. The database holds factory lathe machines definition at the current state, tooling, and the available tools and materials with the recommended machining parameters for each machine-tool-material combination. The developed system is interactive, supported with a powerful graphics package (AutoCAD), which gives the system user the ability to describe the part manufacturing process through direct manipulation of the part and stock in-process drawing with the aid of a user-friendly machining process dialog box. The system offers different types of product documentation files as output. These are the process plan sheet, the computer-aided plan description model, and a DXF (Drawing Exchange File) format, which may be used to exchange product information between the CAD/CAM systems. Finally, the system postprocessor is used to generate NC/CNC Code (G-Code) files necessary to operate the predefined machines to produce the part.

The effect of fiber orientation angle of composite materials on the gear tooth root stresses is investigated analytically to select the required orientation of the fibers inside the gear tooth. This leads to improved gear tooth strength. The study also examines the effect of geometrical parameters (loaded or unloaded pressure angles, number of teeth, radius of fillet, and profile correction) and types of fibers (glass, graphite, and boron). A stress analysis using the finite element method is performed for a reinforced gear subject to bending loads. The results indicate that fiber orientation affects the root stresses of the gear tooth and that there is a direct proportionality between improving the gear strength and geometrical parameters.

This paper introduces an efficient and easy method to superimpose or merge an available digitized aerial photo on the common wireframe digital terrain model (D.T.M.) for a specific region. The goal is to produce what is called a photorealistic digital terrain model (P.D.T.M.) with the aid of Matlab programming language.

This paper presents a summary of the rapid advances in mobile communication systems, specifically the Global System for Mobile Communications (GSM). The research focuses on the development of various techniques such as design, simulation, controlling mechanisms, management protocols, and performance analysis. Several software simulator systems have been designed and implemented to simulate real GSM cellular networks, including calling mechanisms and mobility management. The simulators include models for the GSM Cellular Network, Mobile Station, Base Transceiver Station, Base Station Controller, and Mobile Switching Center. Additionally, Graphical User Interfaces (GUIs) have been developed to analyze and evaluate the performance of the designed cellular network systems under different operating conditions. The study also investigates mathematical approaches for calculating call blocking probability, handoff dropping probability, and optimizing network performance using the guard channel principle.

This study analyzes Baghdad Tower for communications when subjected to earthquake excitation using an elasto-viscoplastic material modeling and a three-dimensional finite element method. The algorithm used in this research deals with nonlinear structural analysis. Newmark's method is employed to study the displacement response under El-Centro earthquake type of excitation.

This study analyzes supersonic gas jets in a confined liquid metal atomizing nozzle using nitrogen at an operation (stagnation) pressure of 1.65 MPa. The study investigates three different ambient pressures (1.25, 1.52, and 1.75 bar) and finds that the nozzle is over-expanded in all cases. The Mach number at the nozzle exit for all cases is 2.64. The study examines the pressure and Mach number of the atomizing gas at various points downstream of the nozzle exit and the effect of heat transfer from the liquid metal (aluminum) on gas flow behavior. The results indicate that the temperature rise of nitrogen due to heat transfer from aluminum is negligible, allowing the flow to be considered adiabatic. The study also finds that the pressure of the atomizing gas adjusts to higher ambient pressure through a weak oblique "lip" shock followed by a reflected weak oblique "edge" shock. As ambient pressure increases, the jet boundary curvature increases, shortening the jet length. To avoid the shock, the difference between ambient and nozzle exit pressures must be decreased, which can be achieved by increasing the operation pressure or decreasing the ambient pressure.

This paper presents a summary of the rapid advances in mobile communication systems, specifically the Global System for Mobile Communications (GSM). The research focuses on the development of various techniques such as design, simulation, controlling mechanisms, management protocols, and performance analysis. Several software simulator systems have been designed and implemented to simulate real GSM cellular networks, including calling mechanisms and mobility management. The simulators include models for the GSM Cellular Network, Mobile Station, Base Transceiver Station, Base Station Controller, and Mobile Switching Center. Additionally, Graphical User Interfaces (GUIs) have been developed to analyze and evaluate the performance of the designed cellular network systems under different operating conditions. The study also investigates mathematical approaches for calculating call blocking probability, handoff dropping probability, and optimizing network performance using the guard channel principle.

A general method using the theory of thin-walled structures is given for determining the natural frequencies and mode shapes for box-girders of varying depth with closed sections, subjected to torsion and bending using a grillage method and finite element method (plate/shell, MSC, NASTRAN). Consistent mass matrices related to torsion and bi-moment effects have been derived using shape functions corresponding to an assumed polynomial deflection configuration, also stiffness and consistent mass matrices for flexural behavior including the effect of shear deformation and rotary inertia in bending. The stiffness matrix for beam elements under non-uniform torsion is presented using the differential equation of equilibrium.

A special computer program is written to perform free vibration analysis starting from the element stiffness and consistent mass matrices. The results have been compared with those obtained from the MSC/NASTRAN package. Numerical examples are presented to show the effect of cell number and the variation of the span/width ratio.

An experimental investigation was conducted to study the effect of operating parameters on the permeable conductivity and product rate for a reverse osmosis process. The parameters studied include the conductivity of feed water in the range of 1000-1500 µS/cm, pH in the range of 4-10, and operating pressure in the range of 3-6 bar. The best operating conditions, which lead to good quantity and quality for water product, are: 1000 µS/cm conductivity of feed water, 7 pH, and 6 bar operating pressure. At these conditions, the permeable conductivity is 52.905 µS/cm, and the product rate is 328.143 l/hr.

This paper discusses the planning of the optimum path for a mobile robot or the optimum trajectory for link movements of a stationary robot to increase efficiency. The objective of the paper is to identify the steps and processes needed for constructing an off-line path planning system using a genetic algorithm, referred to as GPPS. In off-line path planning, the robot is given a map with the location of all obstacles in a given world. The goal is to construct the shortest possible path between a pre-defined start and goal position without running into obstacles. A new operator, called the repair operator, is proposed to eliminate infeasible path segments and remove path points near obstacles. However, the shortest possible path resulting from applying genetic operators and the repair operator may contain overlapping and redundant segments. To address these drawbacks, an enhancement operator is proposed. Eighty experiments are tested on GPPS with different cases, considering the number and distribution of obstacles, the size of obstacles, and the number of experiments per workspace. All experiments aim to provide an acceptable feasible path.