DIYALA JOURNAL OF ENGINEERING SCIENCES

An experimental study has been conducted on steady-state natural convection heat transfer from helical coil tubes. Water was used as a bath liquid without any mixing and air was used as a coolant fluid. A straight copper tube of 13 mm ID, 14 mm OD and 3 m length were bend to fabricate the helical coil. Two coils are used in this experiment has a curvature ratio of 0.1101 and 0.0942. The data were correlated using tube diameter as the characteristic length. The results show that the overall heat transfer coefficient and pressure drop are increased when the flow rate of coolant and curvature ratio increase. Two correlations are presented to calculate the average Nusselt number inside and outside of coil.

This paper deals with the evaluation of the elastic deflections and bending
moments for orthotopically reinforced concrete rectangular slabs supported on three variously
restrained edges with the fourth edge free and subjected to triangular load covering the slab
full area. Six cases are considered for such slabs to cover all possible restraining conditions at
the three supported edges. Based on the finite difference approach, equations are derived to
calculate the maximum values of the positive and negative bending moments as well as the
maximum deflection in any of these six slab cases caused by the applied triangular load

Electron swarm motion across a uniform electric field is calculated and analyzed by a Monte Carlo simulation (MCS) method in the presence of elastic excitation, ionization and attachment collisions cross-section with the electronegative gas. The calculation is carried out for a wide range of E/N values from 71 to 1000Td. It is shown that in the case of a steady –state experiment. The motion has been analyzed to give swarm parameters for (drift velocity, number density, mean energy, and effective ionization coefficient). The first aim of the present paper is to calculate the swarm characteristic at 71 Td by MCS and to discuss the difficulty of calculation al low E/N. The second aim is to calculate the swarm parameter for experimental conditions, i.e., the steady state Townsend (SST). The present results are in excellent an agreement with those deduced by the Boltzmann equation analysis for steady- state and pulse Townsend experiments

CPU scheduling is the basis of multiprogrammed operating system. By switching the CPU among processes, the operating system can make the computer more productive. The objective of multiprogramming is to have some process running at all times, in order to maximize CPU utilization. This paper presents a simulator that uses graphical representation to convey the concepts of various scheduling algorithms for a single CPU. It allows the user to test and increase his understanding of the concepts studied by making his own scheduling decisions, through the very easy graphical user interface of the simulator. It graphically depicts each process in terms of what the process is currently doing against time. Using this representation, it becomes much easier to understand what is going on inside the system and why different set of processes are candidate for allocation of the CPU at different time.In this paper, we introduce the basic scheduling concepts and present several different CPU – scheduling algorithms in visual way.

This research is an experimental investigation on the hydraulic performance of the combined hydraulic jump and plunge pool stilling basin operating under high head for Makhool Dam. Two series of tests are carried out; the first series are on the model as it is designed, while the second series are on a modified model by adding two rows of chute blocks. (81) Experiments are performed on both models. The results indicated that for the first model the stilling basin length can be reduced and there is negative pressure at the beginning of the jump on the sloping apron with high turbulence and unstable water surface. After adding the chute blocks, the tests of the second model indicated that the stilling basin length can be reduced and all pressures are positive with reasonably stable water surface as well as lower turbulence. Therefore, chute blocks are recommended to be added.

Semi conducting Znx Se1-x thin films were prepared at 480nm thickness on glass substrates at room temperature using vacuum evaporation technique. The electrical properties of Znx Se1-x thin films have been investigated, such as dc conductivity and Hall effect. The investigation showed that the composition range 0≤x≤0.3 has an influence on the electrical properties of the Znx Se1-x thin films. The dc conductivity experiment in the range of temperature 293-423 ok gave two activation energies Ea1& Ea2 which represented two types of conduction mechanisms. Ea1 & Ea2 have values 0.6 & 0.1eV respectively for x=0, while 1.01 &0.107 eV for x=0.3. Also, the study showed that the dc conductivity σ=5.19x10-7 (Ω. cm)-1 for x=0, and decreases with increasing zinc to 3.2x 10-7 (Ω. cm)-1 at x=0.3. Hall effect study appeared that the type of the carriers is p-type, their concentration is 1.6x108cm -3 and increases with increasing the fraction of composition x to 2.6x1010 cm-3. Also, the mobility of the carriers has good relation with zinc content x.

Numerical analyses are performed using the ANSYS finite element program to simulate reinforced concrete beams strengthened by carbon fiber reinforced polymer applied at the bottom of these beams. Nonlinear material behavior, as it relates to steel reinforcing bars and plain concrete, and linear behavior for carbon fiber reinforced polymer is simulated using appropriate constitutive models. The results showed that the general behavior of the finite element models represented by the load-deflection curves at midspan show good agreement with the test data from the previous researches. Also, the crack patterns at the failure loads from the finite element models correspond well with the observed failure modes of the experimental beams. The Finite element models represented by this research can be used to work parametric study for the strengthening of beams with CFRP.

Thriving of the society in Zhengzhou city and development of its economy needs scientific and practical solutions of two main problems; natural water shortage and pollution. It is essential to assess the groundwater quality in order to confirm public safety in Zhengzhou and to reduce contamination in there. Fuzzy Synthetic evaluation was applied to delineate the extent of groundwater contamination in Zhengzhou. Assessment of shallow groundwater results concluded that the first three grades of Chinese water quality standards are 91%, whereas the fourth and fifth grades constitute 9% of it. For the deep-water quality, the first two grades are 94% and 6%. It is deduced that part of the shallow groundwater quality is effectively contaminated. Contamination disappears going downward into the deep water. Cluster analysis show exactly same deduction. Fuzzy synthetic evaluation results (using Geographic Information System) were employed to assess the groundwater flow direction around the surveyed wells. It is concluded that infiltration of upstream industrial groundwater is probable into the deep confined groundwater.

This paper focuses on the strengthening of reinforced concrete beams deficient in shear using external bonded Carbon Fiber Reinforced Polymer CFRP laminations. The CFRP laminations can be used to enhance the shear capacity of beams and to change the mode of failure from shear to flexure. The investigation is made in order to estimate the contribution of CFRP reinforcement to the shear capacity of strengthening reinforced concrete beams. The finite element method presented by ANSYS software used for modeling the reinforced concrete beam with CFRP strengthened. The model makes use of the ANSYS software abilities to evaluate the effects of number of parameters (CFRP strap height and thickness, carbon fiber direction with respect to beam longitudinal axis, concrete compressive strength, CFRP strip width and spacing) that are important in the response of the strengthened beam in shear. The numerical results are presented and discussed and conclusions drawn.

The present work deals with the possibility to neglect the assistance gear box. Also, some technological variation is done on the rear and front axle and the garden shaft in order to transfer the motion to the rear axle directly for the landcrouser Vehicle with model “FJ55-LV-KO Japan”. For supposing the number of output cycles from gear box which arrived to low gear box. Counting of decrease cycles, which transfer to the rear wheels with prepearing low gear, and a counting of decrease cycles without low gear. Counting of a cycle torque inside the gear box and a counting of a cycle torque inside the low gear. There is observing for decrease in torque with neglecting the low gear. Happening an increasing with a number of the round, which translated to the back wheels. Happening a decreasing with a torque of the round, which translated to the back wheels.

Asphaltic concrete is considered as a basic support in the construction process generally, and projects of construction and maintenance roads particularly. There is no aspect plants of producing asphaltic concrete depend on realization its own on reduction the costs as possible as they can, the selection of the plant location has great effect in the project success or failure throughout the direct effect on the costs. The plant that has the optimum selections in the location is the one that it can obtain more than others, the different production elements at possible cost lest. Because of the signification of asphaltic concrete plant selection in achievement the plant goals, this demand research on the best methods which help in evaluation these sites, and the Analytic Hierarchy Process is considers one of these methods. The research expresses preparing qualitative and quantitative factors that affect, directly or indirectly, on the selection of the optimum site for asphaltic concrete plants. These factors have been used as a basis to apply the Analytic Hierarchy Process in evaluation the asphaltic concrete plant sites in Diyala governorate to determine the optimum from this aspect. To attain the aim of the research, data have been collected from the literature that deal with the subject of Analytic Hierarchy and the factors effecting selection asphaltic concrete plants, then from the personal interviews with the specialists of designers, constructors and operators for these projects .The results analysis of samples show that the criterions production process input, production process output, production process requirements and qualitative factors have obtained a great portion of relative importance comparatively another criterions between projects . The criterions of production process input and production process output are more important from other criterions in this type of projects. The project Al- Wajhea asphaltic plant had obtained a great portion of relative importance compared with other projects. Finally, a set of conclusions and recommendations have been deduced for different aspects of this subject, such as, the weakness of using the scientific manners to solving the complex problems in great systems management in institutions including AHP method and particularly in the aspect of optimum site selection of projects generally and asphaltic concrete plants particularly.

The results as shown in electrical discharge drilling that surface roughness and metal removal rate increase when current value increases, as well as the results indicated clearly, that the drilling depth of electrical discharge was found to be efficient for deviation of hole dimension between upper and lower surface. Also, the results as showed that the increase in the laser pulse energy over the used level has raised the hole diameter, depth and increased the hole taper. In addition to that the hole taper was affected by the laser energy, the focusing position and focal length of the lens used. However, in hot machining, the tool wear decreases with increasing cutting speeds. The surface of the machined steels was found to improve with in piece work temperature. Also, the results indicate that in hot machining, the tool wear increases in feed rate. It is possible too at any temperature the surface finish deteriorates with increase feed and depth of cutting. The results or this research also shows that the tool wear and surface roughness decrease with increasing piece work Temperature especially when it is compared with the machining at room temperature.