Engineering and Technology Journal

This research studied the effect of adding fly ash and boron carbide (B4C) particulates reinforcement on the mechanical properties and wear resistance of Al- 4.5% Cu- 1.18% Mg matrix alloy. Stir casting method has been used to fabricate the alloy and hybrid composite samples containing 2wt% of B4C and 5, 10, 15،20 wt % fly ash. The x-ray inspection revealed the dispersion of intermetallic compounds (Al2Cu,MgO and SiO2) Also, the mechanical properties have been evaluated, the results showed an increase in the tensile and yield properties with the increase of weight percentage of fly ash content up to 15 wt%, but the elongation decreased, while the hardness increased. Wear rate examination has been concluded by using pin on disc apparatus under different loads of (5, 10, 15) N, sliding velocities (1.413, 2.827, 4.241) mm/sec, and different times of (5, 10, 15) min. The results showed decrease in wear rate at 20% fly ash composite sample when compared with other composites samples and base alloy.

A comparison was made on the mechanical characteristics of binary blends polymethylmethacrylate/ high density polyethylene (PMMA-%HDPE) and vice versa. Analysis of morphology by SEM has been also accomplished. Preparation of polymer blends was performed using melt mixing method by an extruder. Tensile results showed that binary polymer blends (PMMA-%HDPE) indicated an increment in ultimate tensile strength, elastic modulus and shore D hardness compared to (HDPE-%PMMA). The blend of 95%PMMA- 5%HDPE shows superior mechanical properties. SEM results indicated that the prepared blends are not fully compatible with some separated phases of the second polymer dispersed in the matrix

Haptic interfaces for medial simulation prove to be especially useful for training in minimally invasive procedures. In this research, a framework that consists of relevant representation of operator and environment dynamic of a tele-manipulated haptic system is implemented. The uncertainty model of the operator and environment models is considered as well to study the influence on the aspects of stability and performance. The framework of H∞ loop shaping robust controller design is applied, then the stability and performance analysis is investigated. Parametric robust control design method is used as well for comparison. The v-gap metric is considered to develop an accurate measurement of uncertainty. Based on the obtained value of the v-gap an efficient procedure of robust control design is applied. The obtained values of v- gap were 0.1112 for the master and 9.755*10-4 for the slave parts of the haptic system, which indicate improved robustness of stability and performance as compared with the obtained values from parametric robust controller design

The present work studies the mechanical properties of composite materials, experimentally and analytically, that are fabricated by stacking 4-layers of fiberglass reinforced with polyester resin. This plies are tested under dynamic load (fatigue test) in fully reversible tension-compression (R=-1) to estimate the fatigue life of the composite where fatigue performance of fiberglass reinforced composed is an increasingly important consideration especially when designing wind turbine blades. In order to predict fatigue life (Number of cycles to failure), conventional analytical techniques are used in the present work. In addition, Artificial Neural Network (ANN) is a reliable and accurate technique that is used for predicting fatigue life. The used networks are; Feed Forward Neural Network (FFNN), Generalized Regression Neural Network (GRNN) and Radial Bases Function Neural Network (RBFNN). Based on the comparison of the results, it is found that the ANN techniques are better than conventional methods for prediction. The results shows that (RBNN2), where stress load and angle of orientation are input to the network and number of cycles to failure as output, is an efficient tool for prediction and optimization the fatigue life of fiberglass reinforced composite.

Electro spinning is regarded as an active technique for producing biomimetic scaffolds used in tissue engineering applications from synthetic and natural polymers. The technique used in this research gives the ability to produce bio-polymeric materials for fabricating engineered scaffold tissues by preparing (PVA) solution. Ambient temperature at (25, 30, 35, 40, 45 and 50 °C) and needle tip to collector distance with (4, 8, 12, 15, 20 and 22 cm) were studied to optimize the electrospun fibers (size and shape). The electrospun fibers topography were studied by scanning electron microscopy (SEM). Measurements were done for each (SEM) images and lead to determine the mean diameters size of the obtained fibers. Results showed that the average fiber diameter of the (PVA) electrospun decreased to the range (220–500 nm) without creation of any beads, fibers diameter decreased as ambient temperature increase to certain temperature at (45 °C) and retrain to increase at (50 °C) temperature, while increasing the distance of the needle tip to collector decrease the mean nanofiber diameter from (875 nm) at (4 cm) to (600 nm) at (22 cm).

This research involves nano-materials addition and interaction with cement mortar behavior for many mortar samples under variable curing time with constant water to cement ratio (W/C = 0.5). Some mechanical properties such as (compressive and flexural strength tests), durability (by water absorption test) were studied. The effect on the (Al-Mass cement) Ordinary Portland Cement (OPC) type (I) by additives with small amounts of nano-particles (SiO2) and (Al2O3) were investigated in this research. The nano materials additives were added on the mixture of mortar with the percentages (1, 2, 3, 4 and 5%) for both nano materials with constant (W/C) ratio and also the amount of the fine aggregate used three times the amount of cement. The results shows that, the strength of the mortar consist both nano materials give better properties than mortar without nano materials in all tests. But nano silica additive gives good properties up to (3%) than mortar with nano alumina additive which give proprietress up to (2%).

This work aims to model and simulate an absorption cooling system using solar flat- plate receiver with water lithium bromide (li.Br-H2O) mixture as a working fluid, and to select the optimum type for absorption cooling system, which have suitable application in Iraq. Weather conditions for Erbil city have been selected. Coefficient of performance (COP) for a single, double (series and parallel), half and triple effect of an absorption cooling system are calculated and optimized. COP Prediction, hot water temperature, and the rate of heat transfer have been simulated and represented by using TRNSYS and EES programs. Active area of the solar flat-plate receiver is calculated and optimized for five suggested areas of (140, 150, 160, 170, and 180 m 2). Average heating load, average daily - radiation and cooling load for summer months (June, July, August, and September) have been calculated. The results indicated that, the superior type of the four absorption-cooling systems is a single effect, which has COP 80% at generator temperature of (81 °C). Also the results indicated that the optimum area of solar flat-plate receiver was 160 m2 which has achieved the maximum capacity of cooling power and consumed capacity in the generator (50, and 62.5) kW respectively. I think, according to the previous studies , the current work is the first in Iraq because it approved that, single effect type is an efficient and more relevant type for good working under Iraqi climate by using solar flat–plate receiver and suitable to apply it experimentally in a wide range.

Synthetic biomaterials for bone repair and substitute must be yield to critical criteria , one of them, their mechanical properties should not be very less than that for natural bone to prevent fast failure, nor much higher to prevent stress shielding effect which led to fast implant collapse. Other important issue, it should not cause inflammation in implantation region. According to these criteria, many researchers investigated several biomaterials. Titanium dioxide (TiO2) reinforced polyetheretherketone (PEEK) biocomposite is considered a promising biomaterials, because of their superior properties and good biocompatibility with host tissue. Alumina (Al2O3), considered a bio inert ceramic used in this work to modify mechanical properties. Hot pressing technique adopted in this work with pressing pressure of 50 MPa at 370,380,390, and400 C° compounding temperatures to produce different compositions implants. Animal model used to study inflammation behaviour for implants as a comparison with control group. X-Ray radiological test were carried out for both, implants and control regions. Mechanical testing shows good values, similar to natural bone. No inflammation observed in injury area

This search aims to study the effects of (SSSC)”static synchronous series compensator– one of the FACTS devices” – on reducing the power losses and improving voltage profile of Iraqi national grid system. Proposed particle swarm optimization (“PSO”) to determine the optimum location of “SSSC” devices based objective function that depends on the power and voltage as fitness. The proposed algorithm is checked on the IEEE- 9bus. Then is applied on the Iraqi national grid. The results show the ability of the proposed method to determine the optimum location of static synchronous series compensator (SSSc) that reduced losses of active power and improve the bus “voltage profile”. The proposed algorithms are implemented by using MATLAB package version 7.10

Surface roughness and dimensional deviation are critical quality dimensions of machined products and several machining parameters including tool insert dimensional tolerance affect them. Machining performance studies involving dimensional tolerance of the insert during machining, particularly hard face milling do not have considerable attention of the researchers. Therefore, the aim of the present work is to investigate the effect of the dimensional tolerance of the insert along with other machining parameters such as spindle speed, feed per tooth, and depth of cut on the roughness and dimensional deviation simultaneously. Experiments were conducted as per standard L18 mixed orthogonal array on a CNC vertical milling machine. Significance of machining parameters with respect to roughness and dimensional deviation was determined using Analysis of variance (ANOVA). Results revealed that among several machining parameters, feed per tooth greatly affects surface roughness and dimensional deviation. Optimum machining parameters that give minimum values of surface roughness and dimensional deviation simultaneously was obtained using Genetic Algorithm (GA).

This work was carried out to investigate effect of glass fiber (GF) and carbon fiber (CF) on kaolin-clay firebrick properties. GF and CF are considered inorganic fibers with application of high temperatures. Kaolin clay is mixed with short GF and CF separately by different percentages (0, 0.5, 1, 1.5 and 2) wt%. Kaolin-GF and kaolin-CF mixtures were compacted by using the semi-dry pressing method. The compacted specimens were fired at different temperatures (1100, 1200 and 1300)°C. Properties which include bulk density, apparent porosity, water absorption, thermal conductivity and fracture strength were obtained from the firebrick specimens. The results show that the addition of GF has beneficial in lowering of firing temperature, and consequently accelerating the densification via enhanced grain boundary diffusivity. Increasing GF content in the firebrick mixture enhances the fracture strength due to increase amount of glassy and mullite phases. Incorporation of CF has inversely affected than GF on the firebrick properties. As the percentage of CF increased

Pomegranate shells were investigated as green inhibitors for steel 44-2 in 0.1M HCl at various temperatures (30, 40, 50, and 60) °C using electrochemical technique. Five concentrations of inhibitor were added 4, 8, 12, and 16 ppm. Corrosion tests were performed by Potentiostat at 5 mV.sec-1 scan rate and the data measured by Tafel extrapolation method such as Tafel slopes, corrosion current density and corrosion potential. Inhibition efficiencies were calculated and indicated that 8 ppm was the best concentration for inhibition especially at 60oC, where was 96.47%. Pomegranate Shells behaves as anodic inhibitor type and obeys Langmuir adsorption isotherm. The equilibrium constant of the adsorption-desorption process and the apparent free energy of adsorption confirm the physicsorption of Pomegranate shells. FTIR spectroscopy was used to test film formed on steel surface compared with FTIR spectrum of Pomegranate Shells. These spectra confirm the formation of Fe2+Pomegranate shells complex.

A new design approach has been used to achieve a dual band response from a multi-band resonance. The design approach is wholly depending on current distribution analysis on the surface of a multi-band antenna. The proposed multi-band antenna consists of a slotted ground plane with a simple 50-ohm microstrip feed line on the other side of an FR4 substrate having 4.4 relative dielectric constant and 1.6 mm thickness. The geometry of the first iteration Sierpinski curve fractal has been employed to the slotted ground plane antenna structure. Two small squares have been inserted to both internal upper corners of the slotted ground plane as a technique to control the path of electrical current on the surface of the multi-band antenna. With this technique, the resulted antenna can offer two resonating bands with respect to -10 dB S11. The first band (2.28-2.6) GHz, while the second band (5-5.58) GHz. The proposed antennas have been modeled and simulated using two softwares (CST Microwave Studio and High-Frequency Structure Simulation HFSS) to verify the results of both antennas and the other antenna parameters have been studied by using CST only.

This study displays experimental investigation to find out the effect of the external sulfate attack on crack propagation in cement mortar cubes exposed to two sulfate solutions. For this purpose, five mixes of mortar are designed to cast 90 cubes (18 cubes of each mix) and two sulfate solutions (magnesium sulfate MgSO4 and sodium sulfate Na2SO4), each of 34000 p.p.m SO4-2 concentration are prepared. The cubes are evenly distributed in each of the solutions and in tap water as well. The testing technique is carried out compressive strength and Ultrasonic Pulse Velocity (UPV) tests simultaneously to specify the stress/strength ratio at which cracks propagate. The tests are carried out after 56 and 150 days of exposing to sulfate solutions. The results show that crack propagation takes place in specimens exposed to sulfate solutions at stress/strength ratios higher than those which are kept in tap water. The main conclusion, according to this study results, is that sulfate particles delay the propagation of cracks in cement mortar cubes

The stability of tunnels and other underground structures under the influence of dynamic load is one of the important issues that should be studied carefully. The objective of the present paper is to study the effect of the geogrid reinforcement in transfer of the dynamic load to the underground structure. The underground structure was simulated as a plastic pipe within the soil. The investigation focuses on the influence of parameters such as load amplitude, depth of geogrid layer and width of geogrid layer using the finite element method by QUAKE/W computer program for the analysis. It was concluded that when the geogrid reinforcement width equals (1B), the total stress on the crown of pipe decreases by about (17%) compared with unreinforced soil, but this percentage decreases to (10%) when the geogrid width equals to (2B). The percent vertical settlement on the pipe crown decreases by about (35%) when using reinforcement of width equals (2B) compared with test results unreinforced soil, while when the width equals (1B), the percent vertical settlement decreases to about (15%), this indicates that when the width of reinforced soil increases, the vertical settlement decreases.