KUFA JOURNAL OF ENGINEERING

In this study, the Performance Based Design PBD method, which has been used only in seismic design by several codes, has been expanded to be applied to structures exposed to blast loads. The plastic hinge models used in PBD, which currently available for earthquake loads do not represent real behavior under the blast load. An analytical approach was proposed to represent the plastic behavior of flexural response under blast loads. The proposed model considers the following essential phenomena: concrete cover crushing, concrete core crushing, bar buckling in compression reinforcement, strain hardening in tensile reinforcement and softening in reinforcement bar. The proposed analytical approach has been validated with two experimental results of columns applied to blast loads and reasonable results has been seen

This research investigates the influence of recycled mixture modified with styrene-butadiene-styrene (SBS) polymer on rutting resistance. The reclaimed asphalt pavement (RAP) mixture percentages were used 10, 20 and 30% by weight of original mixture and one percentage of SBS polymer which was 5% by weight of asphalt cement. The moisture susceptibility and rutting were taken into consideration in this study. The results indicated that the recycled asphalt mixture containing on SBS polymer gives better moisture susceptibility and better rutting resistance. It is noted that indirect tensile strength ratio (ITSR) increases when adding SBS with 5% percentage polymer and reaching its maximum ratio 94.5% for 20% RAP and the rut depth decreases by 66.7% when adding SBS with 30% RAP content.

The aim of the current research is to investigate the structural behavior of steel-concrete-steel sandwich beams with a new suggested shear connectors. The shear connector was manufactured from deformed rebar in the form of stirrups. Four push out specimens were tested to obtain direct shear strength for the new type of shear connectors. Also four full size steel-concrete-steel sandwich beams were tested under three points loading. All beams were simply supported. The experimental results showed three failure modes as follow: (1) flexural failure; (2) shearing of shear connectors; and (3) buckling in compression plate. The use of proposed shear connectors from deformed steel bars produces a good connection between steel plates and concrete core, where the load capacity of steel-concrete-steel beam with long leg stirrups (L. connector) is larger than other beams. The ultimate load of beam B1 (steel-concrete-steel sandwich beam with L. connector) is 0.125 greater than the ultimate load of beam B2 (steel-concrete-steel sandwich beam with J-hook connectors).

As key elements in plenty of rotating machinery, the elastohydrodynamic performance of journal bearings should be carefully checked in light of the design and operating parameters considered. This first part of the current study aims to numerically analyse the operation of journal bearings under alignment conditions. In the fluid-solid interaction analysis conducted, the lubricant flow field is solved using the finite volume method. Based on finite elements strategy, a structural analysis is then implemented to the solid bearing using the pressure distribution computed earlier on its inner surface. A wide range of operating conditions has been considered including the eccentricity ratio (0.1≤ε≤0.9), bearing length-diameter ratio (0.8≤L/D≤2), and rotation speed (4,000≤N≤10,000 rpm). Three principal categories of operational quantities have inspected, namely; the lubricant pressure distribution, overall performance parameters, and structural aftereffects. Among all the parameters examined, the eccentricity ratio is the most influential one on the performance of journal bearings. As it increases with applying heavier loads, a significant rise occurs in each of the friction force, power loss, stress levels, and deformation on the inner surface of the bearing. The bearing length and rotation speed, on the other hand, affect the bearing performance as well, but to a less extent.

This paper investigates the ability of utilizing the artificial neural network (ANN) in calculating the forced convection characteristics coefficients from internal flow of air inside a pipe subjected to constant heat flux. The heat transfer characteristics such as Nusselt number (Nu), Stanton number (St) and friction factor (f) which are calculated using the empirical correlations have high deviation from that obtained from the experiments. So, the ANN method is proposed for predicting these characteristics coefficients more close to the experimental results. The training and testing data for optimizing the ANN structure are based on the experimental data obtained from the experiments performed on a forced convection apparatus. Three training algorithms for the training of the ANN were used and the presented ANN is implemented by using such MATLAB program. For the preferable ANN structure acquired in the current work, an acceptable mean square error was achieved for the training and test data, using the Trainlm algorithm. The results reveal that the estimated results are very close to the experimental data. Also, a new Graphical User Interface (GUI) is implemented for the application of ANN in the calculation of the attempted heat transfer parameters.

Crude oil ash is the residue that is produced during oil combustion for instance fly ash, bottom ash or boiler slag which was primarily produced from the combustion of coal. With growth in oil burning power station, huge amount of fly ash considered as organic materials which are normally disposed in an on-site disposal system without any commercialization purpose. Previous researchers have studied the extraction of silica from agricultural wastes such as palm ash and rice husk ash (RHA) and FA (fly ash) by using leaching treatment method. In this study, the weaker acid, citric acid solution was used to replace the strong acid in leaching treatment to process. Result showed that the loss on ignition materials can be decrease to 12%. Meanwhile the silica can be extracted up to 54.4% from FA using citric acid leaching treatment under the optimum reaction time of 60 minutes with solution temperature of 60°C and concentration of citric acid 5% receded by gradual combustion at 900°C for 3 hours.

This paper deals with Matlab simulation of Long Term Evolution system (Lte) to show data rate of the uplink layer from user equipment toward the tower with respect to the size of Desecrate Fourier Transform process (DFT) which will be increased from 2 to the size of Inverse Desecrate Fourier Transform process (IDFT). Also it shows the way of using Cyclic Prefix technique (CP) in Lte system and its types which effect on the data rate for uplink layer. Finally the results will show the value of Lte system data rate for different types of modulation and Cyclic Prefix which will be for many types of system bandwidth individually, and it will show the minimum and maximum values of (DFT) process size with the midpoint which is the best one.

The heat lost from gas turbine power plants with exhaust gases represents the most important source for lowering its thermal efficiency. Also, the thermal efficiency of gas turbine can be affected significantly by the ambient surrounding temperature. In Basrah, a lot of gas turbine units have been installed during the last period. In this study, the thermal-economic impact of the heat lost from gas turbine power plant (GTPP) to the atmosphere for different ambient temperature is studied. Heat recovery system is used, the heat recovery system is an absorption refrigeration system used for cooling the air inlet to the gas turbine cycle. For combined system gas turbine-refrigeration cycle, the performance and economic analysis are performed. The results shows that as, the output power and thermal efficiency are decreased by 0.97 MW and 0.0726% respectively for each unit temperature rise of the ambient temperature. The used of the absorption chiller would increase the output power by 23.3%. Also, the thermal efficiency increased by 23.35%.

Utilisation of particles of coconut shell and cow bone as reinforcing materials for the production of low density hybrid polyethylene matrix composites by stir casting method was carried out. 50 µm coconut shell and 50 µm cow bone particulates in different proportions (5 – 25 wt. %) were mixed with polyethylene and the microstructural, physical and mechanical characterisations were determined using standardised methods. The hybrid composite exhibited desirable properties in terms of water absorption (0.3 %) indicating reduced pores/voids. It also exhibited ultimate tensile strength (1.78 MPa) and hardness (12.78 HBN) at 15 wt. % filler addition. The uniform dispersion of the reinforcing particles as observed in the SEM microstructure and the strong adhesion of the particles and polyethylene matrix contributed to the enhancement of the tensile strength and hardness of the composites. Increasing the filler concentration beyond 15 wt. % caused a decrease in the average inter-particle distance/spacing thereby increasing the amount of interparticle stress concentration overlap. This led to higher levels of debonding when tensile stress was applied. This ultimately impaired the tensile strength of the composites. The strain energy stored in the matrix which could be equal to the adhesion/bonding of the particles and polyethylene matrix caused the particle-matrix interface to debond and reduced or impaired the modulus of elasticity of the composites. Generally, the hybrid composites were better than the mono-reinforced composites and unreinforced polyethylene thus showing the efficacy of added particulates. Hence, the development of this biocomposites will reduce environmental pollution and also has the potential for application in areas where low strength composites are required.

The PID controller still remains a widely used and very effective means of achieving stability in control systems. Generally, the performance of the controller is determined by the proportional, integral and derivative gains of the controller. The classical techniques: Ziegler-Nichols (ZN) open loop method; ZN closed loop method; Chien-Hrones-Reswick (C-H-R) load rejection method; and meta-heuristic technique: the fuzzy logic algorithm, are used to determine the tuning parameters of the PID controller in this study. The performance comparison of these controllers is done for automatic generation control (AGC) of a multi-source single-area hydro-thermal-gas power system. In such power systems, each source has a participation factor that determines its contribution to total power generation. The root mean square error (RMSE) is deployed to determine the proportionate balance of each generator’s output with its corresponding participation factor. The performance comparison of the controllers using Simulink/MATLAB shows that the fuzzy-PID controller achieved the most proportionate generation balance.