Engineering and Technology Journal

In this research an experimental study was carried out to investigate the effect of adding marble and porcelain waste as replacement of sand by certain percentages on mechanical properties of concrete containing (100%) recycled coarse aggregate and compare its properties with concrete mixture containing natural coarse and fine aggregate. Four mixes were prepared the first one is the control mix having natural coarse and fine aggregate, second mix containing (100%) recycled aggregate and natural fine aggregate, third mix containing (100%) recycled aggregate and (5%) marble waste as replacement of sand and last mix containing recycled aggregate(100%) and (10%) porcelain waste as replacement of sand.The ratios of Added Materials (marble, porcelain waste) depended on the results obtained from tested cement mortar cubes having different proportions of the two materials, the selected ratios were the ones giving the highest compression strength. The results of tests showed that using of recycled coarse aggregate as alternative to natural coarse aggregate gives good quality concrete and a compressive strength higher than the compressive strength of original concrete by (5.1%) and it helps increasing modulus of rupture by (19.5%) compared to the original concrete. The results show that using recycle aggregate lead to reducing tensile strength by (35%) compared to the original concrete. Using of marble waste as replacement of sand lead to significant increase in compressive strength by (5.1%), while using porcelain waste gives same compressive strength of reference mix. Using marble and porcelain waste lead to significant increase in tensile strength reach to (35%) and (17.6%) respectively. The results show there is an increase in modulus of rupture when using marble and porcelain waste reach to(24%) and (19.5%) respectively, but it reduced workability of concrete mixtures.

This study describes an experimental work that was made to evaluate the effect of wetting and drying cycles on the behavior of concrete specimens externally strengthened with CFRP laminates. The experimental work included testing of twenty-three concrete specimens externally strengthened with CFRP laminates in different positions, with two compressive strength levels. The experimental variables considered in the test program include, compression strength of concrete, number of carbon fiber reinforced polymer (CFRP) strip layers, using CFRP strips throughout the total length of the specimen or within the middle third, and the number of wetting and drying cycles. The testing program included compression strength test, four-point flexural test, direct tension test, single and double face shear tests. The experimental results show that the increasing time of exposure to wetting and drying cycles lead to a significant increase in compressive strength, increasing the cracking loads which reached up to 22%., and decreasing the ultimate load carrying capacity.

This study involved studying fatigue crack propagation in elastic-plastic and linear elastic fracture mechanics LEFM fracture mechanics EPFM for each bovine and cadaveric human cortical bone. The results of the fatigue crack propagation showed that the fatigue crack propagation in elastic-plastic fracture mechanics is better than fatigue crack propagation in linear elastic fracture mechanics for comparison of the bone at small frequencies. Therefore, fatigue crack growth rate in cadaveric human bone is larger than bovine cortical bone. In addition, the cutting of the bone by hand saw is the better method than any an electric cutting machine.

Electrical discharge machining (EDM) is one of non-traditional methods employed to produce complicated forms of electrical conductive materials. This process can be applied to materials difficult to machine with traditional methods. Thus, the study and analysis of EDM variables play an important role to improve the yield, and safety of a surface. This research aims at study and analyze influence of pulse current (Ip) (10, 16, 22) Amp, pulse on time (Ton) (50, 100,150) μs and pulse off time (Toff) (25, 50, 75) μs, (keeping other parameters fixed) on a Recast Layer Thickness (RLT) for machining (AISI 1018 mild carbon steel) using Response Surface Methodology (RSM) within “Minitab 17” for designing of experiments. Optical microscopy and scanning electron microscopy (SEM) was used. Experiments proved that minimum RLT was 5.2 μm at Ip, Ton and Toff at 10Amp, 50 μs and75 μs, respectively. The results also indicated that RLT increased with the increased (Ip and Ton) and decreased in Toff.

Biometric technique includes uniquely identifying person based on their physical or behavioral characteristics. It is mainly used for authentication. Iris scanning is one of the most secure techniques among all biometrics because of its uniqueness and stability (i.e., no two persons in the world can have same iris). For authentication, the feature template in the database and the user template should be the same method for extracting iris template in this proposed system. Also storing the template in the database securely is not a secure approach, because it can be stolen or tampered. To deal with this security issue, the proposed system is securely storing the template in the database by firstly using randomness to scramble the bits of template based on chaos system. Secondly, a hiding technique is utilized to hide the scrambled templates in host images randomly. Finally, a secret sharing based on linear system is implemented on the iris template in database to protect it and adding extra layer of iris authentication system. The proposed secret sharing system has been generated a meaningful shares which overcomes the problem in traditional methods. Also in proposed system, two approaches of iris extraction have been presented.

The effect of flow velocity and chemical composition of Arab gulf sea water on the corrosion behavior of three different types of steel (DNV/EH40, AB/FH32 and ABS DQ47) used in building of marine ship hull structures investigated by using electrochemical Potentiostatic test method was. The results indicate that the general corrosion rate under flow condition is larger than that obtained under static case. Increasing the velocity of sea water leads to increase the corrosion rates for certain limit and then began to decrease. NV/EH40 steel exhibited a significantly lower values of corrosion rate, ABS DQ47 steel has larger values and AB/FH32 marine steel plates has moderate values.

Presently used modern techniques to control instead of the traditional control techniques for many industrial applications virtually or theoretically. In this research, a Fuzzy logic has been applied to control the important variables of steam generator in AL Dura station in Baghdad that generate (160 MW). These controlled variables are pressure, temperature ,air fuel ratio ,lower water level, flame and gas . Fuzzy requires a data, which obtained from actual power plant. This work explains the control on two stages during operation boiler and after operation boiler in order to make a right decision if any faults occurred during these stages at limit conditions based on fuzzy system. It was used simulation of Fuzzy system in MATLAB program. The results showed that the adoption of control technique that based on Fuzzy logic have a high response to indicate the control signals and thus can be depended as an active control system for selecting a right decisions compared with traditional systems. The adoption of fuzzy logic in control system gave the ability to take on decision for control signals with a high stability compared with traditional methods. The fuzzy system contributed in giving prophesies for station case to tell the operator what to do therefore enhancement the performance of station through to take a right decision to avoid stopping. The adoption of mfs in term (trapezoidal) showed a big corresponds with the proposed system and that is through a rapid response. The enhancement of efficiency was 10% when using fuzzy system. The accuracy of fuzzy in control was 0.99 that gave the ability to take on decision for control signals with a high stability compared with traditional methods.

This research includes the evaluation of economic feasibilities based on the Iraqi’s market cost by using three different types of central heating systems in a residential villa located in Duhok city / Iraq. It also compares between modern and conventional central heating systems. A life cycle cost analysis based on detailed heating and operation load profiles considered in this work. Initial, running and maintenance costs for three central heating systems examined for fifteen years as a working period. The used systems in this study were; modern central heating system (heat pump water heater system) and conventional central heating system (fuel oil hot water boiler system and electric hot water boiler system). Transfer function method with hourly analysis program platform (HAP4.9) used for estimation the heating loads within each zone of the project. The proposed technique of modern central heating system found to be more efficient for thermal and economic efficiencies and it uses an environmentally friendly refrigerant such as (R410A). It also works efficiently in severe cold climate with low temperature of (-20°C) in winter season. The results shows that the heat pump water heater central heating system is most efficient system, this system has provided an energy saving range up to 57.5% compared with electric hot water boiler system and 70.6% compared with fuel oil hot water boiler system.

In this study laminate composites were prepared, one was reinforced with three layers of kevlar fibers at (Vf = 17.89%) and the second was reinforced with hybrid laminate with sequence of layers (Kevlar-Glass-kevlar (KGK)) at (Vf = 15.3%), samples were tested before and after silica addition at volume fraction (3%). Tests were (tensile, flexural, impact, hardness, and optical microscope), hand lay-up technique used to prepare samples. Matrix was unsaturated polyester resin. Results showed that mechanical properties (tensile strength, flexural strength, and fracture toughness) decreased after silica addition from (190 MPa, 610 MPa, 35.6 MPa.m1/2 ) to (100.5 MPa, 212MPa, 27.7 MPa.m1/2 ) respectively for composite reinforced with three layers of Kevlar fibers at (Vf = 17.89%) and from (175.5 MPa, 387 MPa, 32.36 MPa.m1/2 ) to (67.6 MPa, 210 MPa, 23 MPa.m1/2 ) respectively for laminate composite with layers (Kevlar-Glass-Kevlar (KGK)) at (Vf = 15.3%). Hardness increased after addition of silica from (79.25 to 81.2) for composite with three layers of Kevlar fibers at (Vf = 17.89%) and from (80 to 82.3) for composite with layers (Kevlar-Glass-Kevlar (KGK)). Optical microscope showed that layers were distributed in matrix and addition of silica leads to delamination of composite after using flexural test.

This paper investigate some mechanical properties of no-fines concrete produced by using demolished concrete as coarse aggregate after crushing to different sizes. Different no-fine mixes were considered using Portland cement type I with two types of coarse aggregates, crushed natural gravel and crushed demolished concrete were used with two ratios by weight (1:5 and 1:7) cement/aggregate. Single size and graded aggregate were used with a maximum size of 20 mm. W /C ratio was kept as 0.4 for all mixes and supper plasticizer was used to keep the same flow and compaction factor value for all mixes . Using demolished concrete as coarse aggregate in no fine concrete led to decrease in the workability. As a comparison with natural coarse aggregate mixes, the average percentages of decreases for the flow, compaction factor and the fresh density were 2%, 2.3% and 6.4%, respectively. As well as the test results indicated that the compressive strength, splitting tensile strength, flexural strength and oven dry density for no fine made with crushed demolished concrete at age 28 days were decreased by about 29%, 22 %, 21% and 4% respectively as compared with no fine made by natural crushed aggregate.

In the current paper, an experimental analysis on Al-sheet (AA 1050) with thickness 0.9 mm to reveal the effect of relevant forming factors on the formed thickness in two-point incremental forming (TPIF) process has been conducted. The formed thickness of pyramid-like shapes was analyzed by studying seven variables: die geometry, tool diameter, tool path, stepover, tool shape, lubricant and slope angle. The proposed analysis utilizes Box-Behnken design of experiment (BBD), main effects plot (MEP) and analysis of variance (ANOVA) for sake of studying the influences of the seven forming factors on the resulted thickness. The results of these analyses have indicated that the most significant factor affecting the formed thickness is the die geometry followed by tool shape, lubricant and stepover respectively for both slope angles of the pyramid. In addition, it has been found that the other variables have also significant effects on the formed thickness at both slopes of the pyramids produced.

In this paper, a demonstration for an experimental study to measure mean fluid velocity in minichannels is presented. Fluid flow velocity was estimated by applying cross correlation technique on measured thermal fluctuation using two ultra-small thermistors in every channel. These experiments were conducted on two flow field plates (single serpentine and parallel Z-type arrangement) with dimensions (L*W*H= 75*70*3

The main goal of this work is to understanding the requirements to realize the synthesis of MAX phases in bulk form at high temperature. The phase stability of three different MAX phase systems Ti-Al-C,Cr-Al-C and V-Al-C has been investigated along this line. High purity powders were used as raw materials. They were mixed and then compacted under the pressure of 20 MPa. The compacted mixture was heated in an Ar atmosphere at a temperature range of (1000-1400) °C for (2-4) h. Finally, the sample was cooled down to room temperature. X-ray diffraction indicates that systems show a direct formation of MAX phase under these conditions. The SEM and optical microscopy results were used to confirm the structural features of the ternary phases and the less segregation or agglomeration. The results of sintering temperatures versus final density were discussed in terms of physical properties evaluation and hardness for indicate the mechanical properties. Finally, the differential scanning calorimetric results over the range of 25 to 650 ºC show that the reactions in all systems related directly to the Al melting point. It is obvious that the reactions in all these systems started at ~600 ºC that may support this attitude. It is expected to contribute towards a better basic understanding of this fascinating class of solids. Furthermore, we try to evaluate the here-proposed novel low temperature synthesis for other Mn+1AXn systems. This may release a new synthesis route for the mass production of materials with rather unique properties.

In this work, magnesium oxide micro/nano particles were prepared using laser ablation in deionized water. This is technique very simple, cheap and a single step method. In the present work, at which ablation of pure Mg metal target in deionized water was accomplished using 9nsec Q-switched Nd:YAG laser at 1064 nm laser wavelength, the effect of laser energy on particle size material and the effect of number of laser pulses on optical properties and surface morphology have been studied. UV-visible measurement showed that a red shift in the absorption spectra of MgO NPs is obtained with increasing number of laser pulses. X-ray Florence's (XRF) investigation showed the Mg metal powder percentage purities. Particle size analysis (PZA) investigation showed the particle size distribution of magnesium in deionized water after laser ablation. Atomic force microscope (AFM) investigation showed that magnesium oxide nanoparticles have root mean square of surface roughness 0.954 nm and particle size distribution of magnesium was (15-155)nm after laser ablation.

A considerable amount of research work has been performed on the effects of vibrating of fresh concrete on the reduction of shrinkage and creep, the improvement bond stress between reinforcing bar and concrete, reduction the concrete permeability and improvement of the mechanical properties of concrete (tension and compression). Series of tests on reinforced concrete circular column, cubes and cylinders were carried out to study the effect of re-vibration duration on axial strength of column, compression strength of concrete cubes, and tensile strength of cylinders. Different compressive strengths of concrete and different size of aggregate were considered in this investigation. The test results show that, the re-vibration operation improves the tensile and compressive strength of concrete. The stiffness of columns increased with increasing the re-vibration duration up to1.5 times the initial vibration duration. Size of aggregate has significant effect on the improvement properties of concrete due to re-vibration. Increase the time duration of re-vibration delay the appearance of first crack.