AL-Rafidain Engineering Journal (AREJ)

This research contains a study of the effect of connecting square steel pieces (10mm) thick with dimensions (20×20,25×25,30×30mm) by welding with the ends of reinforced steel bars with diameters (10,12,16mm) embedded in fibrous concrete with a percentage volume of steel fibers (0.0,0.4,0.8,1.2%) over the development length required to reach steel reinforcement to yield strength ( )in case of straight reinforcement steel bars with the same diameters without steel headed.

The present investigation examines experimentally the behavior and ultimate shear strength of reinforced high-strength concrete corbels subjected to vertical load. The experimental investigation consist of casting and testing fourteen reinforced high-strength concrete corbels, the main variables studied were concrete compressive strength (40 to 62 MPa), main reinforcement ratio (0.517 %, 0.776 % and 1.034 %), shear reinforcement stress (ρhfyh=1.535, 2.305 and 3.071 MPa), and the ratio of outside depth to the total depth of the corbel (k/h= 0.24 to 1.00). The results indicate that high-strength concrete corbels (fc'= 40 to 62 MPa) behaved similarly to those made with normal strength concrete, the increase in compressive strength of concrete leads to increase in ultimate shear strength with ductile failure. By increasing fc' from 40 to 62 MPa for ρh.fyh equal to 1.535 MPa and 2.305 MPa, the ultimate shear strength increased by about 20.8% and 27.5% respectively. An increase in ρw by about 100% caused an increase in load carrying capacity by about 27.7%. Also by increasing ρh.fyh by about 100%, the ultimate shear strength increased by about 14.7% and 11.1% for corbels with fc' equal to 40 and 49 MPa respectively, while for corbels with fc' equal to 62 MPa, an increase in horizontal shear reinforcement stress (ρh.fyh) by about 50% caused an increase in ultimate shear strength by about 12.3%, and this indicate that the contribution of horizontal stirrups in increasing ultimate shear strength was more efficient for corbels having compressive strength equal to 62 MPa. As (k/h) increased from 0.24 to 1.00, the ultimate shear strength increased by 11.5%.

This study has been done due to the raising importance of aluminum in drinking water from health point of view. Survey of Al+3 concentrations has been done in Tigris river, in the water purification plants and water supply network. These plants are the larger ones in the city ( unified right side plant, Al-Qubba plant, the old left side plant ( Al-Arabi restrict) and Al-Danadan complex project). Results revealed that the Al+3 concentration on the river (through Mosul city) ranged from 7-37μg/L. The plants have increased this concentration in raining times (turbidity increasing times) to about 25-50 μg/L (ppb), because of adding alum in its work. Water distribution network does not affect the residual Al+3 in this study. There was a correlation between Al+3 and temperature. Finally, it can be said that Al+3 concentration in drinking water is in the safe side according to several international health organizations if the plants do not add alum.

Failure of earth dams can be caused also by seepage problems, foundation instability, deformation, surface sliding, and earthquakes. The most critical conditions that may cause failure of the embankment are: differential settlement, development of shearing within the embankment and foundation, and development of seepage through the embankment and foundation. The stability and factor of safety against Mosul dam embankment sliding are determined considering a possible rapid drawdown and earthquake conditions and using three methods. Unsaturated condition was considered assuming the shear strength parameter (b) to be (0, 0.5, ). GEO-SLOPE OFFICE was used as the analytical tool to simulate both seepage, slope stability, and earthquake. Seepage through dam was analyzed for three period rapid drawdown of water level (30,21,8 day) with the associated saturated-unsaturated transient seepage. The main results indicated that the minimum slope stability factors of safety were reached using Bishop method and was achieved during 8 day water drawdown and within the second day which indicates the most critical case.

The shocks became an important issue in operating wastewater treatment plant, because it may lead to biological unit damage in a short time. This study had been done to experience two separated ways in toxic shock happening prediction. Two glass basin (10L volume) used to conduct the study. The work was with completely mixed activated sludge. The studied ways of prediction were 1-the specific oxygen uptake rate (SOUR) of biomass in aeration tank , and 2-microscopic images monitoring. Two types of toxic material were used , the first was phenol (organic) and cyanide (inorganic inhibitors) with 40mg/l concentration in each of the basin separately. The results revealed that the two ways were useful in shock prediction. SOUR has raised with phenol shock in a short time , and has sharp dropped with cyanide shock (about 15 min.). the microscopic images revealed that filamentous growth happened in the bioflocs after short time of phenol shock. While a dispersed growth and pinpoint flocculation has appeared after short time of cyanide shock (leading to the biomass damage).

Recently huge amount of various by-product materials have been produced from industrials. These materials have detrimental effects on the environment. Hence, the re-use of such materials for different purposes as for construction work or other activities is essential goal of this study. Because some of geotechnical problems are associated with the gypseous soils as a foundation, hence the waste lime as one of the by–product material has been added to improve their properties. In addition, the combined additives of waste lime plus cement have been examined and compared with those treated either with waste lime or cement. Soil with 23% gypsum content has been treated with waste lime up to 8% and combined additives of waste lime plus cement by percentages of (4%+8%, 6%+8% and 8%+8%). These mixtures have been compared with the soil stabilized with cement up to 16%. The results indicated the efficiency of the combined additives of waste lime and cement in the improvement of compressive and tensile strengths of gypseous soil. The treated soil becomes more durable against the cycles of wetting and drying. Samples treated with cement or combined additives gain more durable ability, while those treated with waste lime alone fail under durability circumstances (wetting and drying cycles). The combined additive of waste lime plus cement (4%+8% and 6%+8%) is approximately equivalent to the 16% cement from strengths view point. Accordingly, this would reduce the amount of cement required for stabilization about 50% by using waste lime.

Operational Research had its origins during the Second Word War as the result of the cooperation of scientists with senior officers of the Royal Air Force , to look into several military problems . " In 1947, G . Dantzig developed an efficient method called , the simplex method, which can be used with the aid of the computer to solve linear programming problems even with thousands of constraints and thousands of variables in order to find their optimal solutions " [2] . This research is aiming to revise comprehensively the procedure of Simplex method and to use the computer programme WINQSB in order to obtain the optimal decision to minimize the production cost for three different jackets models in Najaf Factory for Men Clothes

Scanners are used to convert analogue photography into digital format. High quality and precision photogrammetric scanners are not easily reachable due to their high cost. This paper investigates a new strategy to test a sample low cost desktop scanner to estimate the achievable precision of the product. The digitization quality of the test pattern is investigated at different warm up times and different positions in the scanning area. Notes are given on the performance of the scanner in geometric and radiometric aspects that are essential for photogrammetric applications.

In this paper we introduction a new design programming to graphic user interface (GUI) in MATLAB v.6.5. this program gives to the user ability of using it in the design of the Erbium Doped Fiber Amplifier (EDFA) through the easiness, flexibility, and clear figures with multi options to help the user to choose and design the amplifier through the best gain and noise figure

The paper reports preliminary data on the characteristics of a new electronic switching device based on CdS/CdTe hetero–junction. The device is polar and is switched from OFF to ON (WRITE) or ON to OFF (ERASE) by voltage opposite signs. The threshold voltage for WRITE operation is (3-4 V), depending on the device, and for ERASE is about (-2V). The OFF and ON resistance are typically 40MΩ, and 1.5kΩ respectively. Particularly notable features of the new memory device are its transition times (100µsec for both the WRITE or ERASE operations).

Providing electrical power in developing countries is something hard to do for many reasons that could be financial, technical and even the lack of raw materials. Therefore, the need for new technique for fairly power distribution is more attractive. From this an idea comes to make new sophisticated distributed network system which controls power consumption for the given inhibited area. The system should give a certain amount of power for each consumer .When the consumer reaches his limit the system will take an action to increase the limit if power is available or disconnect the overloaded consumer for a specified time. the present work is devoted to design a system which has an ability of controlling the power consumption by using network processor. the designed overall system is fulfilled through four distinct stages; each stage has a predefined job. The four stages communicate with each other using TCP/IP protocols suit. Therefore, a TCP/IP stack should be available at each stage.

This paper describes a new proposed architecture for tolerating faults in hypercube multiprocessor DSP system. The architecture considered employs the TMS320C40 DSP processors as processing node. The system has a single spare DSP processor assigned to each cluster ( a group of four nodes ). Each pair of clusters share one FPGA unit connected to every node in the two clusters plus the two spare processors. The FPGA units in the system are devoted for data routing, data distributing (in real time processing), diagnosis, system reconfiguration and expanding. Every 3D hypercube has additional spare processors connected to FPGA device of that cube. The spare nodes are used in two stages to tolerate more than one faulty node in each cluster with a low overhead and minimum performance degradation. The system makes use 50% hardware redundancy in the form of spare nodes to achieve fault tolerance. The effectiveness of interprocessor communications and the mechanism of fault detection( for one and two fault ) has been successively simulated using (Xilinx Foundation F2.1i) simulator

The current work focused on the influence of cooling rate on the microstructure, mechanical and tribological properties of cast in-situ composite. It was observed that the size of intermetallic phase Mn(Al1-xFex)6 and the dendrite arm spacing (DAS) increases considerably with decreasing cooling rate of the cast ingot. Microstructural examination of these different cast in-situ composites shows that there is no significant difference in the size of the in-situ formed alumina particle. Superior mechanical properties, as indicated by ultimate tensile stress, yield stress, percentage elongation and hardness, are obtained when the in-situ composites are processed by cooling the cast ingot in water, resulting in refined microstructure. Higher hardness due to refined microstructure and superior mechanical properties result in decreased wear rate in cast in-situ composites cooled in water after casting, compared to the wear rates observed in cast ingots cooled either in air or inside furnace. Cast in-situ composite cooled in water after casting, shows higher coefficient of friction compared to those cooled in air or inside furnace.

The increased role of advanced materials in mechanical design optimization has purred the development of new material types and combinations previously unavailable to the designer. These new materials give the designer the ability to design higher density systems by matching the material characteristics of all parts within the system. Certain metal matrix composites now allow the designer to select needed material properties over a fairly large range for example (thermal expansion, conductivity and material strength).The current work has been made for the evaluation of coefficient of thermal expansions (CTE) of Aluminum based cast composites reinforced with mixture of (Al2O3 ) and (SiC) particles with different volume fraction. The cast composites have been prepared by liquid metallurgical route. The results show that (CTE) significantly increased with increasing temperature up to 400 C. But it has been observed that (CTE) decreases with increasing volume fraction of reinforcing particles. The (CTE) values were found to be comparable with theoretical results. Turner model showed good agreement with the current experimental results

This work is focused on the numerical study of steady, laminar natural convection heat transfer in square enclosure with perfectly conducting thin fins. The fins are attached to both vertical surfaces, the two vertical surfaces are at different temperatures while the other two horizontal surfaces are insulated. In the formulation of governing differential equations, mass, momentum and energy equations are applied to the enclosure. To solve the governing differential equations a finite difference method is used. Three cases were studied in this work depending on the number of fins attached to vertical surface, (i) single fin (ii) two fins and (iii) three fins. The results presented for various Rayleigh number and dimensionless fins length ( in the range of 0.15, 0.25, 0.35, 0.45), in a form of streamlines, isotherm lines, as well as Nusselt number. It was observed that the increasing in Rayleigh number resulting in increase inNusselt number and in the temperature gradient. Due to increasing in the in the dimensionless length and number of fins, it was observed that a decrease in temperature gradient and in the Nusselt number were occurred.