DIYALA JOURNAL OF ENGINEERING SCIENCES

The shear failure of reinforced concrete beams considered as a very complex fracture phenomenon for which a purely mathematical approach is not possible at present. However, detailed modeling of the fracture mechanism is not necessary for establishing the general form of the size effect. This paper reports the details of the finite element analysis using "ANSYS" program for eight large-size reinforced concrete beams. The beams were analyzed without web reinforcements to evaluate the nominal shear strength provided by the concrete. The main variables included in the study are the a/d, concrete compressive strength
, and the type (conventional or high-strength steel) and amount of the longitudinal steel reinforcement. The finite element models are developed using a smeared cracking approach for reinforced concrete. The concrete is modeled using "SOLID65"eight node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The steel reinforcement has been modeled discreetly using "LINK8" 3D spar element and it has two nodes. A comparison between the finite element analysis results, namely, loads, deflections and cracking behavior and the available experimental results were made and good agreement was obtained. Results show that the use of high strength steel as a longitudinal reinforcement improves the shear strength and post cracking tensile stiffness of the concrete.

A design of rubber components against fatigue failure is one of the critical issues to prevent the failures during the operation. Therefore; fatigue life prediction was the key technologies to assure the safety reliability of mechanical rubber. In present study, mechanical properties of natural rubber and fatigue life (constant amplitude stresses) were carried out experimentally at room temperature and 40 oC. The mechanical properties and constant fatigue life were compared with previous study. Tensile and Fatigue life tests were performed using Dumb-bell specimens. The experimental mechanical properties and fatigue life of natural rubber component agreed fairly with the published data of previous study above. While the mechanical properties and fatigue lives at 40 oC were decreased with about 33% of tensile properties at 0.2 strain and about 99% fatigue properties at 5x106 cycles compared with room temperature.

Hypereutectic Al-Si casting alloys are attractive candidates for connecting rod applications in compressors. Several hypo- and hypereutectic Al-Si alloys were produced by pressure die casting and thixoforming in this search. Hypereutectic Al—Si alloys were less than the near-eutectic and hypoeutectic alloys under the sever were conditions encountered in compressors, confirming the impact of Si on were resistance. Cu also improves were properties. The thixoformed alloys were at comparable rates with pressure die cast alloys at lower Si levels, implying that the lower Si content of the former is compensated for by the thixoforming processing route. Hypereutectic composition, uniform dispersion of fine Si particles and thixoforming as the production route are all good for a superior wear performance, However, does not translate into a sizable improvement in wear resistance of the thixoformed alloys.

Emulsion breaking is one of complex process used in many practical applications such as the petroleum industry, painting and waste-water treatment in environmental technology. Chemical demulsification is the most widely resolved method of treating water-in-crude oil emulsions and involves the addition of chemical reagents to destroy the protective action of emulsifying agents and allow accelerating the emulsion breaking process. Our experimental results showed that, the addition of glycols chemicals as a cosolvents like ethylene glycol methyl ether (EGME), monoethylene glycol (MEG), polyethylene glycol (PEG-1500), in combination with commercial demulsifier RP-6000 will enhancing the process of emulsion demulsification. The demulsification experiments were carried out at controlled temperature 65oC and screened by bottle test using about 100 ppm demulsifier doses. The maximum amount of water separated after 120 min found to be 87.7% for (75/25) (RP6000/PEG1500). Where, the water separations for (75/25) (RP6000/MEG) and (75/25) (RP6000/EGME) for demulsifier were 71% and 65.2% respectively.

The performance and reliability of the Internet depend in large part on the operation of the underlying routing protocols. Today\'s IP routing protocols compute paths based on the network topology and configuration parameters, without regard to the current traffic load on the routers and links. This paper discusses routing optimization using Genetic Algorithm Then we study and analyze the problems of routing optimization in large networks. We will propose a detailed genetic algorithm in order to optimize routing tables and to enhance the performance of the routers.

Secured wireless computer networks are more important because signals are available through air and it’s easier to attacks from passive eavesdropping and active interfering. Now it was suffered from more problems, one from these problems is attach from the users and hackers. Therefore, wireless computer networks security is very important to solve or decrease this attach, a lot of researches were worked improved wireless security in this field but in different ways and different methods. This project had been represented how to prevent hackers’ accessing to the server, by using encryption to media access control “MAC address” from the two ends (server and user), using RSA public-key cryptosystem.

Large development that happens in computers technology leads to the use of modern programs and pollutant about different forming processes from through design and analysis for geometric forms by using Finite Element Method F.E.M, which gives accurate results which approaches experimental results. This study depends on local coordinates system by using rotation of local coordinates for nodes on region contact length between metal and die. This is to calculate relative extrusion pressure and study the effect of relative die length on the relative extrusion pressure for reduction of area (20%, 40%, 60%, 80%) with friction factor (0.1) by using software ANSYS program. The contours for distribution of stresses and plastic strains were obtained, to obtain perfect die length that is needed to less extrusion pressure. The results of this study are compared with experimental result and upper bound theory and have shown a good agreement with a minimum discrepancy.

A complete model of liquid-phase dispersion was used to simultaneously characterize axial and radial mixing in bubble column of 0.15 m inside diameter and plastic plate distributor with holes of 2 mm diameter. Axial and radial dispersion coefficients and mixing times were determined in tap water for superficial gas velocities in the range 0.6-5.36 cm/s. The experiments were carried out using a transient method (the tracer response method). The dispersion coefficient was obtained by adjusting the experimental profiles of tracer concentration with the predictions of the model. The measured axial dispersion coefficients (Dax,L) were generally consistent with the predictions of the well established correlations, thus validating the complete dispersion model used in the analysis. The Dax,L values ranged from 110 to 200 cm2/s. There was evidence that the existing literature data on Dax,L in bubble columns are slightly underestimated, as consistent underestimation was found to be a characteristic of the widely used dispersion model that disregards radial dispersion. The value of the radial dispersion coefficient was typically about 1 to 2% of the Dax,L value under any given condition. The mixing time data were generally consistent with the existing literature. The results of this study are compared with experimental result and upper bound theory and have shown a good agreement with a minimum discrepancy.

A complete model of liquid-phase dispersion was used to simultaneously characterize axial and radial mixing in bubble column of 0.15 m inside diameter and plastic plate distributor with holes of 2 mm diameter. Axial and radial dispersion coefficients and mixing times were determined in tap water for superficial gas velocities in the range 0.6-5.36 cm/s. The experiments were carried out using a transient method (the tracer response method). The dispersion coefficient was obtained by adjusting the experimental profiles of tracer concentration with the predictions of the model. The measured axial dispersion coefficients (Dax,L) were generally consistent with the predictions of the well established correlations, thus validating the complete dispersion model used in the analysis. The Dax,L values ranged from 110 to 200 cm2/s. There was evidence that the existing literature data on Dax,L in bubble columns are slightly underestimated, as consistent underestimation was found to be a characteristic of the widely used dispersion model that disregards radial dispersion. The value of the radial dispersion coefficient was typically about 1 to 2% of the Dax,L value under any given condition. The mixing time data were generally consistent with the existing literature. The results of this study are compared with experimental result and upper bound theory and have shown a good agreement with a minimum discrepancy.

In this research, new easy and fast correlations derived from practical data for the design single phase squirrel cage induction motor that enable us to select its main dimensions with depending on the required power, also making empirical correlations connecting between the motor power and its dimensions for multi-ranges. Data of these correlations were got practically and formulated mathematically by using Mathematical Matrix Model is called Pseudo Inverse.

This paper studies the effect of methanol on catalytic conversion for
Yemeni gasoline distillate. In this investigation, a modified zeolite catalyst carried by
aluminum-silicate is used for increasing of reaction area and decreasing of operation
temperature. Operation conditions are 500 & 540 C 0 and atmospheric pressure. In
presence of methanol, it is noted that the conversion percentage increases up to higher level
(from 47 % to 86 %). This positive effect leads to increase the yield of aromatic (from 22 %
to 34 % wt.) and olefins (from 20 % to 40.1 % wt.). Besides that, it is found that the addition
of methanol allows decreasing the temperature of process from 540 C 0 to 500 C 0 with the
conservative of the same conversion point and required productions at catalytic conversion
for individual gasoline