Vol. 22 No. 1 (2014)
Articles
Abstract: The design optimization of deep drawing process in manufacturing is proposed to control the final shape of the work piece after elastic spring back. The manufacturing process design problem is formulated to minimize the difference between the shape of the desired work piece geometry and the final analysis. This paper aims to predict the wrinkling and thinning (necking) failure and to study the effect of using draw bead on the thickness distribution along the cup. In this paper to analysis the deep drawing process with draw beads the FEM code (ANSYS) version 12.1 packages is used, which is able to simulate various metal forming processes such as deep drawing. The best results and the low variation between the maximum thickness and minimum thickness is found at the half circle shapes of Draw Bead and itَ s about 10.4% thinning and 26.5% thickening
Abstract: The present research aims to study the feasibility of using a Stochastic Dynamic Programming model "SDP" to calculate the optimal operating policy for a single reservoir system. The study required to write two computer codes; one is for Deterministic Dynamic Programming "DDP" and the other is for Stochastic Dynamic Programming "SDP" using MATLAB platform. A comparison study has been conducted between the optimal operating policies obtained from the two models. The results revealed that the SDP outputs were more realistic than those obtained by DDP, as the first gives the reservoir operator more flexibility to deal with the variation of the inflow to the reservoir, while the second is not. Additionally, a simple nomographhas been introduced to assist the operator of the reservoir to manage a wide variety of inflow scenarios.
Abstract: In this study, the multilayer composite plates consist from aluminum, brass, and steel with unsaturated polyester Resin (UPE) as a core material. The plates having a central circular, elliptical holes. The buckling parameters such as aspect ratios and different hole orientation angles have been analyzed numerically.These parameters have been applied at different layers of materials both metallic and non metallic. Analyses were carried out using finite element method (FEM) through the application of special numerical program written in APDL by ANSYS software. Result shows that the buckling load were highly dependent on the type of composite material, and the buckling load increased by increasing elliptical hole orientation angle. Increasing of major and minor diameters of elliptical holes with plate b/w ratios were decrease the buckling load for the multilayer composite plate
Abstract: In this research the rainfall intensity data in mm/hr for the period ( 1982-1990 ) of nine years are collected for duration 3 to 13 hour from a station at Hamam - Al Alil ( Small town 25 km from Mosul ). Data generation for long period is generated from the historical records by using uniform and normal distribution. Physical and Statistical tests for comparing the historical and generated data will indicate that Markov process of 1st degree is better than 2nd degree for two distribution.
Abstract: Main landing gear is important part in aircraft, its help the aircraft to takeoff ,landing, and taxing in the ground .This part subject to high stress at landing due to impact, there are two important force act on landing gear during touch, Normal force and a spin-up back force .Normal Force is a great force that act on landing gear and its generate due to Normal impact and its cause to bend landing gear to up , this force can be calculated form Newton second law, and the spin-up back force generated at touch when the tire not rotate causing the landing gear leg to bend to backward the value of this value can be assumed equals to 0.5 from the normal force. In this study this forces type are considered to make stress analysis of the landing gear for Cessna 152 during touchdown time, after that three model are considered to reduce value of stress on this landing gear by keeping the dimension and material as on original model and making positive curves on the landing gear leg, and shown that when making the positive curve this will reduce the value of the stress and deflection on the landing gear depending on the principle of bending moment in the beams.
Abstract: Data of monthly volumes of discharges reaching Mosul Dam reservoir for a period of (15) years, multiplied by (12) month and thus get a time series consisting of (180) value for monthly volumes of discharges are organized and collected for years ( 1985 – 1999 ). A synthetic time series were obtained by applying multiplicative decomposition of a time series method. Where normal method (which depends on the values of the two components (trend and seasonal) only) was applied on the historical data after conversion to the normal distribution , and the standard error (MAPE) of this method was (39%). For the purpose of improving the results were an amendment in this research on this method by using the modified method in this research which adopting the values of components other than the series (cycles and random) and enter them in the calculation the values of synthetic time series by multiplying their approximate values in the results of the values of synthetic time series extracted by the normal method above , in terms of improved the error measure value (MAPE) of the modified method to (32%). The results showed the effectiveness of the modified method used in this research in the prediction of incoming water volumes for years ( 2000 – 2004 ), where tests showed conformity (average, standard deviation, autocorrelation coefficient, density analysis) and there is a match between the predicted values with historical values.
Abstract: Eccentricity problem is considered as one of the most important and common repeated problems in rotary shafts in all machines. This will lead to generation of vibration and extra loads on bearings. Also a non-uniformity can occur in distribution of applied load on all the surface of the bearing which being concentrated on one or two sides of the bearing surface. The purpose of this research is to investigate the effect of the unbalance on the values of stresses and deflections for a flexible rotor supported by oil film bearings. Various rotational speeds and unbalance effects has been taken in to consideration. A dynamical model of the system has been built. The parameters of journal bearing have been determined using MATLAB/ simulink software. ANSYS program has been used for the analysis of the stresses produced during rotation. Keywords: Unbalance, Eccentricity, Simulation, Rotor Shaft.
Abstract: The architectural cultural heritage of any nation is one of the most important basic components that reflect the authenticity and depth civilization of that nations. Architecture as a mirror that reflects all aspects of life (social, economic, technical, environmental, political) of the nation in any age of the ages. many studies focused on research in the local historical properties of the nation to define the architectural privacy (planning, design) to those of the nation. Many of the studies that analysis of Islamic buildings in Arab city are indicated that courtyard is one of the most important elements in both religious, civil architecture and often is used in the hot regions despite differing effects of social, cultural and religious aspects indicator a success architect solution for the different functional needs. The idea of courtyard is dominated the design ideas in a different buildings where it was restrict the design process as it a restriction to the different functional needs and reflected to the traditional architectural composition. Islamic palaces buildings are represented various aspects of life, there are a reflection of social and economic life and political across of different time periods that have passed the nation , and the nature of the climatic conditions . From the previous studies that focused on the courtyard in architectural environment specially in Islamic palaces buildings appears that of the Intelligibility of the Special System of these buildings is insufficiency and unclearness in this studies. this paper has taken this as a research case , and will aims to be determined by Analysis a select group of various and different functional type of Islamic palaces
Abstract: The effect of modified Rayleigh number, positions and lengths of two perpendicular heated surfaces on natural convection heat transfer was studied numerically, where the two surfaces are embedded in square cavity filled with saturated porous medium. All walls of the cavity are kept at constant temperature. Indirect numerical method was used to solve the governing equations, which are: the nondimensional Darcy flow equation as well as the non-dimensional energy equation, which were solved numerically by finite difference method using Gauss-Seidel iteration coupled with (Successive Under Relaxation) technique. This study covered a wide range of modified Rayleigh number range (100-1000), nine positions and the ratios of length of vertical surface to the horizontal (0.5,1, 2). It was found that the positions of two heated surfaces have small effect on the heat transfer rate, but any increase in the length of two surfaces leads to an increase in average Nusselt number, but an increase in the length of vertical surface leads to more increase in the average Nusselt number
Abstract: In the last decade, the value of freehand drawing as a design tool in both education and practice is open to debate as a result of the accessibility of digitised drawing tools such as CAD systems and the relative ease with which a design can be presented and realised using computerised techniques such as parametric modelling and rapid prototyping. The conceptual design stage is the most critical in the design process. Despite the fact that most of the widespread computer aided design systems (such as AutoCAD and 3DSMax) are primarily directed towards the more detailed stage of design process. Even so, there are architects today who have abandoned the use of a pencil and paper, turning to the computer during the creation of their design concepts. The paper investigates the limitations of Computer Aided Drawing (CAD) systems which make them unable to satisfy what freehand drawings are doing for the initial design phase. To achieve this aim, the first section of this paper puts forward a framework for the main roles of freehand drawings through the conceptual design process. The second section investigates the capabilities of computer aided drawing tools to achieve these roles by depending on the theory and practice of the use of CAD tools at the initial design stage. The third section concludes the weakness and strength of computer aided drawing systems in the conceptual design phase. The paper ends with recommendations.
Abstract: This paper study the effect of radiation on a steady mixed convection flow of a viscous incompressible electrically conducting and radiating fluid over an isothermal vertical wedge embedded in a porous medium. The governing nonlinear partial differential equations and their boundary conditions are transformed into a nonsimilar form by using a suitable dimensionless variables. The system of nonsimilar equations is solved numerically using a finite difference method. The present results of local Nusselt number are compared with previously published work for the case of Darcy solution. The comparison is found to be in excellent agreement. The present results showed that as the wedge angle parameter increases the local Nusselt number increases. Increasing in the value of the square of the Hartmann number leads to decreasing the value of the local Nusselt number. Increasing in the value of the radiation parameter leads to an increase in the value of the local Nusselt number. Increasing in the value of the heat generation parameter leads to decreasing the value of the local Nusselt number. Increasing in the value of the radiation parameter in the presence of the square of the Hartmann number and the heat generation parameter has a similar effect on the local Nusselt number presented above but with less values.
Abstract: Corrosion of five steel bodies of passenger cars of models 1985, 1990, 1995, 2000, & 2005 that are used in Mosul city were studied under atmospheric and aqueous during 2009-2010. Atmospheric corrosion rates were below 1.7 mpy, which is classified as low corrosion, this is due to dry weather conditions during the study period , and the quality of steels of the car bodies. Aqueous corrosion rates were also low, below 4.57mpy, and this is due to good water quality of Mosul , low Langelier saturation index, ideal corrosion index, and the quality of steel body cars. Key Words: Mosul city, Atmospheric Corrosion, Car Body Steels, 2010.
Abstract: Multiple access interferences are the major limiting factors for the performance of multihop WiMAX based Mesh Network (WMN). The routing algorithms play an important role in reducing such interferences among the nodes of the WMN. In this paper a new Routing Tree Construction Algorithm (RTCA) which is based on Balancing the data and Parallelizing the routes of the data from nodes to BS is proposed and called Balanced- Paralleled RTCA (Bala-Para-RTCA). This algorithm has a new Down-Node Group Testing (DNGT) feature. This feature increases the conversion of primary into secondary interferences which (in conjunction with directivity) can be avoided significantly by the Modified Fair Relay Centralized Scheduling (MFRCS) algorithm, as a result concurrent transmissions over a certain slot will be increased. So system performance is enhanced in terms of scheduling length, links concurrency ratio (LCR) and average transmission delay (ATD). Without directivity and relative to the standard Breadth First Tree (BFT) RTCA, the simulation results of the proposed RTCA show concurrency ratio enhancement of 15.38% and 19.4% without and with DNGT respectively
Abstract: Many researchers have sought to use different methods to reduce harmonics in the input current wave of the rectifier, In this study the method of passive filter connections are used, which is the most commonly used method. The filters that have been used in this study are connected in parallel (shunt) with the rectifier. Where the idea of these filters to provide a path with a very low impedance to the harmonics of the current. These filters must be capable of withstanding rated voltage of the system. In this study two types of passive filters are explained and used (Single tuned filter and Second order high-pass filters). Also mathematical analysis of these types of filters and waves are given. Filters were designed at several values of the firing angles of the rectifier.
Abstract: In this research, five experimental plants have been established and operated using synthetic domestic wastewater in order to study the effect of some operational parameters on the removal efficiency of organic and nutrients pollutants in Bardenpho Process. The results of the research proved that the removal efficiency of organic, nitrogen, and phosphorus materials were higher in the reactors that work by Bardenpho process comparing to the ordinary activated sludge system. Also the biological sludge resulted from Bardenpho reactors has better settling characteristics. Likewise, the pH values in the plants work by Bardenpho process were lower than those in the plant that work by ordinary activated sludge system. The results of the study also shown that the removal efficiency of organic materials in the Bardenpho reactors increases by the reduction of volumetric ratio of the anaerobic to aerobic zone, in contrast, the concentrations of Nitrate, Ammonia, and Phosphate decrease by the reduction this ratio, in addition, the value of SVI decreases by increasing the size of anaerobic zone. On the other hand, The results also proved that increasing the hydraulic detention time (HRT) lead to increase the efficiency of removing organic, nitrogen, and phosphorus materials of the biological reactors that work by Bardenpho process. Moreover, increasing the HRT leads to increase value of the sludge volume index (SVI) at all of the Bardenpho and ordinary activated sludge reactors. In contrast, the value of pH drops by the increasing of hydraulic detention time.
Abstract: Resistive switching random access memory is one of the novel nonvolatile memory technologies that, has a promising future for replacing the conventional FLASH memory. In this work a detailed study made about the types of operations and understanding the mechanisms of the resistance changing in the device. SnO2 thin films are deposited by using Thermal Vacuum Evaporation deposition method at room temperature on Al/glass substrate to produce Al/SnO2/Al/glass device structure. Optical properties are taken to measure the optical band gap of SnO2. Resistive switching is observed by taking current voltage readings at room temperature. RRAM cell showed unipolar resistive switching behavior with no overlapping between reset and set voltage (1.5V, 2.5V respectively) ,also between high and low resistance states (7.7KΩ,106Ω). Good retention and endurance are obtained and the ratio between HRS to LRS has been found to be at least (41) within 21 cycles
Abstract: The aim of this study is finding the optimum cost design of reinforced concrete columns with all loading conditions (axially, uniaxially and biaxially loaded) using the Genetic Algorithms GAs. Many design constraints were used to cover all the reliable design results, such as limiting the cross sectional dimensions, limiting the reinforcement ratio and even the behavior of the optimally designed sections. Each of the designed columns was handled by the GAs solver according to its loading condition specifications. The load contour method was used to design the biaxial sections with the adjustment of the plastic centroid. A long column constraint was introduced to limit the design procedure with the short columns only. The optimum results were compared with other published works, and a reduction in design cost of the biaxially loaded columns of about 26 % was achieved using the GAs design method while a small percent in the cost reduction ( 1 – 3 % ) was achieved for the uniaxially designed sections, while 50% was the cost savings in the axially loaded columns. It was proved that the genetic algorithm is capable for designing optimum columns sections despite the complex constraints that control the designing procedure
Abstract: In this paper, the parameters of the LTE system in DL are investigated. These parameters include the effect of the Hybrid Adaptive Repeat and Request henceforth (HARQ) on the Signal to Noise Ratio (SNR), Block Error Rate (BLER), and throughput. The paper deals with three cases of Channel Quality Indicator (CQI): 3,7 and 15.The results showed that the HARQ procedure can improve the BLER and the throughput when the retransmission between the evolved base station (eNodeB) and a User Equipment (UE) increased