Engineering and Technology Journal

As the reactive powder concrete (RPC) represents one of the ultra-high performance concrete types that recently used in public works and in the presence of several attempts that aims to examine the behavior of RPC, this work aims to theoretically study the bond stress between RPC and steel bars and the corresponding slip for large reactive powder concrete beams by using finite element models done by ANSYS 16.1 software. Where, these numerical models were verified through several comparisons between their results, and the experimental one from previous work, in which good agreement were achieved. The effects of several parameters on the bond stress were studied, the parameters include concrete compressive strength, and steel fibers content, bar diameter, length of the developed bar and concrete cover thickness.

This paper investigates experimentally the torsional behaviour of hybrid reinforced concrete beams composed of reactive powder concrete (RPC) at the outer edges of the cross-section and conventional concrete (CC) at the inner parts of the cross-section. Hybrid reinforced concrete members are used extensively to deal with the members strength requirements related to flexural, shear and torsion in structural systems. The torsion failure is undesirable because of its brittle nature, it is obligatory to avoid this kind of failure in the earthquake areas. Seven reinforced concrete beams, with dimensions (100X200X1500 mm), the interior dimensions of hybrid beams of the cross-sectional area (20mm width and 120mm height) with 1500 mm length were cast and tested to failure using two opposite cantilevers steel arms that contribute to transferring the torque to the centre of the beam. The first beam was RPC, the second beam was CC and the other five beams were all poured as hybrid ones. Experimental data of the ultimate capacity, cracking torsional loads, the failure pattern and twisting angle for each beam were gained. Experimental results showed higher value of ultimate torsional strength of hybrid beams than CC ones by about (50) % and lower than reactive powder concrete specimen by about (16.67) % for both varying steel fibre and spacing of stirrups.

Dynamic behavior of a copper pipe conveying fluid at different fluid temperatures is investigated experimentally. Three types of supports are used, which are simply support - simply support, fixed – fixed support and fixed – free support. The effect of the support's types on the frequency and the amplitude of vibration for the pipe conveying the fluid are studied for various flow temperature. These vibration characteristics were tested at temperatures 50, 65 and 80 ºC

The damage caused by large earthquakes is not only due to structures but also due to the soil failure, where the dynamic response varies considerably from the fixed base state because of the interaction between the ground and the structure. The main objective of this paper is to study the effect of the infinitely extended soil on the dynamic response of the structure. A three-dimensional dynamic analysis of reinforced concrete building
considering the effect of soil-structure interaction is performed. Building with a different number of stories rest on soil with various characteristics have been taken into consideration. For simulation of wave propagation due to far-field effects, coupled finite-infinite elements is presented for modeling the soil. The infinite boundary provides a powerful tool for dealing with wave propagation problems. The analysis is performed through a finite element method which is implemented in ABAQUS program. An earthquake load is applied in the horizontal direction with various boundary conditions such as; free, and infinite boundary. The effect of boundary on the dynamic response of structure are investigated. The significant difference in dynamic response is observed when infinite boundaries are used, especially in the case of soft soil, where the existence of infinite elements leads to absorption of energy and thus greatly reduce the lateral displacement of the structure

This research had been done to investigate the effect of adding natural powder of Pistachio Shell to PMMA, which popularly used in denture applications. The powder added in different weights fraction (3%, 6%, 9%, and 12%), and different average particle size (53μm, 106 μm, 150 μm, and 212μm %), and studying Compression Strength, Surface Hardness, and Density properties. Hand Lay-Up represented the method used to prepare the specimens in this research. The results were statistically analyzed by SPSS (one-way ANOVA) to determine the mean value and showed a significant difference for each particle size. The highest value of compression strength and surface hardness of PMMA composite specimens happened at (9%wt.) of the filler particles. Also the results represented that the density values for the composite specimens are increased with increasing the weight fraction of the filler particles.

The main objective of this study is to study the synergic effect of fly ash (FA) and high reactivity Attapulgite (HRA) when using them together in ternary blended cement of (OPC+FA+HRA) and evaluate the efficiency factor of FA and HRA in binary blended cement and (FA+HRA) in ternary blended cement. To achieve this objective compressive strength of binary blended cement mixes of (OPC+FA) with FA replacement percentages of (20 %, 30% and 40%), (OPC+HRA) with HRA replacement percentages of (5 and 10%) by weight of cement and ternary blended cement mixes of (OPC+FA+5% and/or 10%HRA) were tested and compared with that of reference mix at ages of (7, 28, 56 and 90) days to assess the synergic effect of FA and HRA in ternary blended cement. The results showed that using ternary blended cement of (OPC+FA+5% and/or 10%HRA) led to increase compressive strength relative to binary blended cement mixes of (OPC+FA) at the same replacement percentages by weight of cement. More significant increments in compressive strength were noticed at age of 7 days. The results showed also that the efficiency factors calculated according to modified bolmoy΄s equation for ternary blended cement were always higher than their corresponding binary blended cement of (OPC+.FA). .

The cement mortar used in rendering external walls, in Iraqi hot weather summer, suffers from appearance of many cracks on surface during and after its setting. So, this research aims to study the effect of different factors that can affect those cracks. The studied variables include mix proportions of mortar, grading of the used sand, method of curing, and environmental temperature (rendering during winter or summer). The rendering was laid on two types of walls build from clay bricks or concrete blocks. Tests were carried out on the mortar mixes of the different variables including flow test and drying shrinkage. Results indicate that the suitable flow of cement mortar for rendering should be 190±10%, which means the water content should be higher than that required for standard flow of 110±5% by 10%. Also, found that the amount of cement and water content and fineness of sand have an important role in the appearance of cracks on the cement rendering. Those cracks can be reduced to large extent by a continuous water spraying twice daily for seven days

The aim of this paper is to design and study a powerful second-order sliding mode controller for electrical servo drive systems. The suggested controller can successfully overcome the chattering problem that was usually facing such systems during operation. The first (1-SMC) and second (2-SMC) sliding mode controllers are nonlinear controllers’ techniques capable of stabilizing the output of a plant, even though a disturbance and parameter uncertainty is present. The asymptotically stable is the significant property of 1-SMC as well as 2-SMC. Despite the robustness of the 1- SMC, in real-time but it suffers from a large settling time and a chattering (undesirable rapid oscillations) of system trajectory close to the sliding surface. The chattering must be reduced because of its negative impact on system stability. The chattering can be reduced by replacing the sign function, used in classical sliding mode, by a saturation function. In the current study, the Second Order Sliding Mode Controller (2-SMC) is used to overcome the drawbacks of 1- SMC by reducing both the chattering and the settling time of the control action. The Electrical Servo drive system was adopted in this paper for testing; both, the 1-SMC as well as the 2-SMC. The comparison of results between the two controllers indicated smaller chattering and settling time in the 2-SMC than that in the 1-SMC. The simulation results of this work were obtained by using the Matlab programming.

Turbo codes are widely used in digital communication systems. Their ability to reach the Shannon channel capacity made it the choice for most of the communication systems. Due to the huge amount of the transmitted data, there is a need to increase the processing speed of the encoders. The researchers used the state space technique to enhance the throughput of the turbo encoder. They apply it to increase the turbo encoder throughput from one bit per cycle up to 8 bit per cycle. The researchers applied the state space method to a three-flip flop, eight state Recursive Systematic Convolution Code circuit to achieve their goal. In this paper, we explored the state space technique and applied it to a four flip-flop Recursive Systematic Convolution Code circuit so that we can achieve a throughput of 16 bit per cycle. The circuit was designed and tested using MATLAB then implemented using FPGA to verif

This work aims to a development of mechanical properties of PMMA that is utilized in denture material, by using two types of polymers; blends (PMMA:2%NR) and (PMMA:2%SR) as a matrix materials strengthen with natural nanoparticles from the pomegranate peel powder (PPP) that were added at different weight fractions (0.0, 0.1%, 0.3%, 0.5% and 0.7%). Two groups of bio nanocomposites specimens were prepared, using (Hand Lay-Up) method. Experimental tests were carried out on surface roughness, hardness and wear rate as well as analyzing of FTIR test. The minimum values of surface roughness and wear rate were reached 1.51 nm and 0.317×10-8 g/cm respectively for polymer blend nanocomposite ((PMMA:2%NR): 0.7% PPP). Whereas, the maximum value of Shore D hardness reached 90 for the same sample of nanocomposites. According to these results, it can be a concluded that the addition of Nano pomegranate powder and natural rubber can develop the mechanical properties of PMMA material used in medical applications.

The present work is aimed to improve the surface cracks density of electrical discharge machining (EDM) by Electrical Discharge Machining (EDM)/Electrochemical Machining (ECM) EDM/ECM hybrid process. A hybrid method of EDM-ECM combined processing involve EDM shaping as well as electrochemical machining (ECM) finishing, also, they are conducted in sequence one same machine tool, same electrode, yet on the different dielectric. In this study, the used workpiece material is the A2-Tool Steel material, while the electrode material is copper. The influence of controllable parameters could be identified via response surface methodology (RSM), these controllable effects include: pulse current, pulse on time, pulse off time, gap, voltage, and electrolyte concentration on surface cracks density (SCD). It has been noticed that model has been developed by RSM adequacy is acceptable because the coefficient of determination is closest to one for SCD, whereas the optimal solution achieved by Desirability Function Analysis (DFA) are (current =42 A, pulse-on time =100 , and pulse-off time =50 )in addition to that, the generated surface doesn’t have any crack which has been generated via EDM are removed entirely through ECM finishing..

This paper introduces a nonlinear (Proportional-Integral-Derivative Neural Network) (PID NN) controller for a differential wheeled mobile robot trajectory tracking problem. This neural controller is built based on the principles of neural network (NN) and the equation of conventional structure of PID controller and is applied on kinematic model of the mobile robot. The particle swarm optimization algorithm (PSO) is utilized to find the best values of three PID NN parameters and connection weights that minimize the error between the reference path and the actual path. The results illustrate that the PID NN controller has a satisfied ability to make the mobile robot tracking any path with good performance, high accuracy and acceptable robustness