KUFA JOURNAL OF ENGINEERING

In the present study, the microstructure, mechanical and wear characteristics of commercial Cu-30Zn brass alloy were developed by an equal channel-angular process (ECAP) using a particular die in constant dimensions. The ECAP process was experimentally conducted at room temperature using (1-4) passes in route C with lubricating conditions. Also, the post-annealing treatment at 350 oC has been done for some brass samples, which were deformed with four passes. Findings revealed that by conducting the ECAP, a significant reduction in the grain size of the deformed brass samples is achieved compared to the as-received alloy. The grain refinement increased with the increasing number of ECAP passes. However, the post-annealing treatment increased the grain size of the deformed brass alloy, but still it was lower than the as-received alloy. Moreover, the mechanical performance, i.e. micro-hardness and strength, was significantly enhanced after the ECAP. The samples processed with three passes presented the highest hardness value (237 HV) and mechanical strength (UTS= 692 MPa, and YS= 542 MPa) due to the homogeneous strain hardening and substantial grain refinement throughout the ECAP process. However, the micro-hardness and mechanical strength of brass alloy decreased after post-annealing treatment compared to those of the ECAP deformed samples. The elongation to failure also decreased greatly with increasing the number of passes of ECAP. Additionally, the wear resistance of the investigated samples increased significantly after increasing the number of ECAP passes compared to the as-received alloy. The highest wear resistance has been achieved for samples deformed by three and four passes of ECAP due to the considerable grain size refinement and higher hardness. However, a slight increase in the wear rate occurred after post-annealing treatment on a brass alloy sample processed with four passes due to the increase in grain size.

QCA technology presented as a new paradigm to replace CMOS technology in the nanoscale. QCA technology represents binary information by cell polarization, not as a voltage level. The basic blocks in QCA technology are the majority gate and inverter. Efficient building blocks are important to get whole efficient circuits. This article aims to present novel configurations for the inverter block that offer advantages in terms of temperature tolerance, cell count, and area efficiency. Moreover, a Repeater gate with high efficiency is proposed to demonstrate their versatility. The proposed inverter has efficient improvements by 2%, 4.4%, 11%, and 17.5% over the best-reported inverter block at 10 K, 100 K, 150 K, and 200 K, respectively. The circuits presented in this study were designed and validated using QCADesigner software v 2.0.3, and the energy consumption of the proposed designs was assessed using QCAPro tools.

The objective of this research is to experimentally study the flexural behavior of hybrid reinforced concrete beams. Three test beams, each with dimensions of (2200 X 150 X 240) mm, were fabricated for this purpose. The first beam was constructed using ordinary concrete, while the second beam consisted of two layers of high-strength concrete in the compression zone and normal concrete in the tension zone. The third beam was entirely cast using high-strength concrete. In terms of reinforcement, all beams were equipped with 2φ12 steel bars in the tension zone and 2φ12 steel bars in the compression zone. Additionally, φ12 steel bars were employed to resist shear forces, distributed along the length of the beams with a spacing of 125 mm c/c. Two-point loading was applied to all beams until failure occurred. The results obtained from the experimental tests reveal that the use of hybrid concrete beams enhances the ultimate load capacity by approximately 20.93%. On the other hand, beams constructed entirely from high-strength concrete exhibited an increase in failure load capacity by approximately 28.68%.

Due to their unique heat transfer features, graphite foams are used in the current analysis to form heat sinks effective enough to dissipate extreme heat generated within high-performance electronics. The heat sinks proposed are formed from foamed-baffles arranged either in parallel or perpendicular to the coolant paths through the staggered slots in between to alleviate the penalty of pressure drop while maintaining high heat dissipation capability. Two different sorts of dielectric coolants namely, air and the FC-3283 electronic liquid developed by 3MTM, have been utilized to directly dissipate the heat generated. The feasibility of the currently proposed heat sinks has been examined numerically based on the volume averaging concept of porous media employing the local thermal non-equilibrium model to account for interstitial heat exchange between the foam solid matrix and the fluid particles flowing across. A wide range of design parameters has been tested including the heat sink configuration along with structural characteristics of the graphite foam used. It has been found that foam baffles oriented perpendicular to the path of coolant flow can dissipate heat by about 50% better than those parallel to it, but with higher pressure losses. It has also been found that heat dissipation capability, for a certain orientation of baffles, can be improved by up to 100% when the foam pore size is doubled with outstanding saving in pressure losses by up to 300%. The impact of operating conditions, including the coolant flowrate and the heat flux applied, has also been inspected. The currently proposed heat sinks have been found efficient to meet the thermal demands of high-performance electronics and sweep away the extreme heat generated there with reasonable cost of pressure drop, where the proper selection of design parameters in light of the operating conditions applied can prevent the emergence of hot spots entirely. Extreme operating conditions, i.e. with heat density of up to 10W/cm2 for air-cooled heat sinks and 100W/cm2 for those cooled with FC-3283, can be well managed when a heat sink is configured from baffles that are oriented perpendicularly to the coolant flow path and formed of graphite foam having low porosity (∅=0.8) and larger pore size

This study investigated the physical, mechanical and thermal characteristics of insulating refractory bricks produced from Nigerian clay blended with melon seed husk. The aim is to reduce the cost of production which arises from importation. This is due to lack of high-quality domestic insulating refractory bricks in most high temperature industries in Nigeria. The test samples were produced by mixing clay and melon seed husk having grain sizes of 212 - 300 μm. The samples were oven dried and fired at temperatures 950℃ to 1150℃ at 50℃ intervals. Physical, mechanical, thermal tests, chemical compositions, Mineralogical and Microstructural analysis were conducted. The results showed that, clay with 25 and 30 wt.% melon seed husks possessed the required refractory properties with cold crushing strength above the recommended ASTM Standard of 1000 kN/m2.

The recent reports of road traffic accident statistics in Iraq have disclosed a rise in the number of crash injuries resulted from the use of mobile phone while driving. This paper aims to explore the factors contributing to the occurrence and prevalence of such crashes and near crashes in Al-Najaf governorate, Iraq. A representative sample of 417 drivers were interviewed as part of a questionnaire driving survey. Several frequency and modelling analyses were conducted using the IBM SPSS software. The frequency analysis revealed a high use of mobile phones for calling and texting activities while driving. Almost 20% and 55% of the interviewed drivers reported their involvement in a crash or in a near crash because of such use, respectively. Regarding the developed logistic models, the crash involvement sequential regression analysis revealed that factors such gender, education, handheld phoning, calling-answering frequency, and inadequate driving can affect the likelihood of crash occurrence. In contrast, the ordinal logistic near miss models revealed that age, gender, high phone use rate, and improper driving due to such use are influential factors in rising the likelihood of being in multiple near crashes. The analysis results confirm the influence of using phones in distracting the attention of drivers and hence threating their lives; as a result, these findings would be enlightening for agencies and policy makers interested in highway safety.

The indiscriminate disposal of waste into various dumpsites with noncompliance to the existing environmental laws and the inadequate provision for leachate containments had resulted in the degradation of environmental resources over the years. The research investigated the practicability of enhanced termite mound-bentonite mixture as an alternate landfill bottom liner. The percentage weight ratio of mound soil and bentonite used for the experimental study were (100:0), (95:5), (90:10) and (85:15) respectively. The study was conducted on a pilot scale artificial landfill (800 x 800 x 400 mm) with four sections AX, AY, BX and BY. Bottom liner was exposed to wastewater for 26 weeks retention period. The pilot scale experimental study revealed that liner mixtures in sections AX, AY and BX failed during the 6, 11 and 17th week retention periods respectively with a corresponding seepage amounting to , and mm3 respectively. However, no seepage was recorded for liner mixture in section BY which connotes that wastewater leakage was prevented throughout the experimental framework. Conclusively, the application of termite mound soil enhanced with 15% bentonite is recommended as a bottom liner in a waste containment system.

Titanium (Ti) and its alloys are frequently employed in the biomedical industry because they have a high corrosion resistance in addition to being lightweight, non-toxic, and having excellent biocompatibility. In this work, the microstructure and some required properties were evaluated for binary Ti-15Zr alloy produced by powder metallurgy (PM) for biomedical applications; the obtained results were also compared to that of commercially pure Ti (CP-Ti). The major goal of this paper is to study the impact of Zr addition on the microstructure, micro-hardness, and corrosion resistance of Ti alloy.

The discharge of effluent polluted with heavy metals have become a growing concern for researchers around the world. This study evaluated the removal efficiency of commercial activated carbon and rice husk activated carbon as adsorbents for the removal of copper ion in water. A nominal size of 1 mm was obtained after sieving the Rice Husk, washed with distilled water, dried in an oven t at 80 ℃ for 12 hours, and pyrolyzed in a furnace at 550 ℃ for 30 minutes. The chars produced were later air-dried and then activated with lemon juice. The Rice Husk Activated Carbon (RHAC) and Commercial Activated Carbon (CAC) purchased from the market were both subjected to the following analyses: bulk density, X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) in order to characterise the adsorbents and to understand their suitability for the removal of copper ion in water. One of the properties of an adsorbent is large pores which is exhibited by the activated carbons as revealed by the SEM analysis. Likewise, the XRF and EDX analyses confirmed that the adsorbents had larger proportion of Silica (50.1 – 50.25%), Carbon (60.06 – 84.87 wt .%) and Oxygen (15.13 – 21.60 wt. %) which is a property of a good adsorbent. BET analysis showed that the surface areas of the rice husk activated carbon and the commercial activated carbon were 998.35 and 1208.25 m2/g, respectively. The bulk densities of the rice husk activated carbon and the commercial activated carbon were 0.3325 and 0.2812 g/cm3, respectively. The maximum removal efficiency using RHAC was observed at 60 ℃ and 120 minutes at 83.96 and 89.21 %, respectively while for CAC the maximum removal efficiency was observed at 60 ℃ at 84.61 % and 30 minutes at 83.3 %. Initial concentration of 20 mg/l was observed to have the highest removal efficiency for the two activated carbon specimens. The modelled effect of initial concentration, temperature and contact time on removal efficiency yielded R2 values of 1, 0.918; 1,1 and 1,1 respectively for the CAC and RHAC.