Journal of Engineering

This research concerns the study of crack growth in the wall of pipes made of low carbon steel under impact load and the effect of moisture (rate of moisture 50%). The environmental conditions were controlled using high accuracy digital control with sensors. The pipe already had a crack. The test was performed on two types of specimens, one with a length of 100 cm and the other with a length of 50 cm. The results showed that when humidity was applied to the pipe, the crack growth was enhanced (i.e., the number of cycles needed to grow the crack was reduced). Additionally, when the test was performed on the specimens of length 50 cm, the number of cycles needed to grow the crack increased due to the effect of bending stress on the pipes.

This paper presents an experimental and theoretical analysis to investigate the two-phase flow boiling heat transfer coefficient and pressure drop of the refrigerant R-134a in the evaporator test section of the refrigeration system under different operating conditions. The test conditions considered are for heat flux (13.7-36.6) kW/m², mass flux (52-105) kg/m².s, vapor quality (0.2-1), and saturation temperature (-15 to -3.7) ˚C. Experiments were carried out using a test rig for a 310W capacity refrigeration system, which is designed and constructed in the current work. Investigating the experimental results has revealed that the enhancement in local heat transfer coefficient for relatively higher heat flux 36.6 kW/m² was about 38% compared to 13.7 kW/m² at constant operating conditions. The enhancement in heat transfer coefficient was about 57% when the mass flux increased from 52 kg/m².s to 105 kg/m².s at constant test conditions. The enhancement in the heat transfer coefficient was about 64% when the saturation temperature increased from -8 to -3.7 at fixed refrigerant mass velocity and heat flux. The effect of mass velocity on pressure drop was relatively higher by about 27% than that for heat flux at specified test conditions. The comparison between the experimental and theoretical results has shown an acceptable agreement with an average deviation of 21%.

Aluminum Metal Matrix Composites (ALMMCs) were prepared using the stir casting technique for AA 7075 aluminum alloy as a matrix reinforced with SiC particles at various percentages (3, 6, 9, and 12 wt.%) and 75µm in grain size. The prepared composite material can be used for many applications such as aerospace, automobiles, and many industrial sectors. Abrasive wear tests were carried out in two stages: the first stage involved changing the emery papers at various grit sizes (180, 320, 500, and 1000µm) with a constant applied load of 15N. The second stage involved changing the applied loads (5, 10, 15, 20, and 25N) with a constant emery paper grit size of 320µm. Microstructure examination, hardness tests, and roughness tests were performed before and after the abrasive wear test. The results showed that increasing the weight percentage of the reinforcement material led to increased hardness, roughness, and improved abrasive wear resistance.

This study investigates the synthesis and characterization of titanium dioxide (TiO₂) nanoparticles under different pH conditions. Ethanol was used as a solvent, titanium isopropoxide (TTIP) as a precursor, and hydrochloric acid or ammonium hydroxide as stabilizers. The study examined the influence of pH on the morphology of the synthesized TiO₂ nanoparticles. X-ray diffraction (XRD) showed that rutile structures are more favorable at low temperatures and acidic conditions, while anatase phase is more pronounced at low and average temperatures with basic conditions. Scanning electron microscopy (SEM) was used to observe the crystalline form and confirm the crystallite size growth. Atomic force microscopy (AFM) confirmed the relationship between roughness and thickness with pH levels

Furfural is a toxic aromatic aldehyde that can cause severe environmental problems, especially in wastewater from petroleum refinery units. In this study, sawdust, a by-product from the local furniture manufacturing industry, was used as raw material for the preparation of activated carbon, which was chemically activated with phosphoric acid. The effect of various adsorption variables, including initial pH of the solution (2-9), agitation speed (50-250 rpm), agitation time (15-120 min), initial concentration of furfural (50-250 ppm), and amount of adsorbent material (0.5-2.5 g), were investigated in a batch process to achieve maximum furfural removal from wastewater. The results showed that the percentage removal of furfural increased with increasing pH and agitation speed until a maximum value, after which it decreased. The removal also increased with the amount of adsorbent material and agitation time until reaching a constant value, and decreased with increasing furfural concentration. The maximum removal percentage of furfural was 97.8%, 94.4%, and 55.9% for prepared activated carbon, commercial activated carbon, and raw sawdust, respectively, under optimal conditions

This paper presents a cognition path planning with control algorithm design for a nonholonomic wheeled mobile robot based on Particle Swarm Optimization (PSO) algorithm. The aim of this work is to propose the circular roadmap (CRM) method to plan and generate optimal path with free navigation as well as to propose a nonlinear MIMO-PID-MENN controller in order to track the wheeled mobile robot on the reference path. The PSO is used to find an online tune the control parameters of the proposed controller to get the best torques actions for the wheeled mobile robot. The numerical simulation results based on the Matlab package show that the proposed structure has a precise and highly accurate distance of the generated reference path as well as it has obtained a perfect torque control action without spikes and no saturation torque state that leads to minimize the tracking error for the wheeled mobile robot.

Porcelain is one of the most important ceramic materials with a wide range of traditional and technical applications. Since most mixtures of porcelain have a high sintering temperature, bentonite has been added in this research to improve the characteristics of sintering and burning. The porcelain mixture consisted of the following Iraqi raw materials: 30% wt kaolin, 30 wt% non-plastic clay (grog), 10% wt sodium feldspar, 10 wt% potassium feldspar and 20 wt% flint. After the mechanical mixing process and transfer the powder mixture to the slurry by adding distilled water, then different weight percentage of the sodium bentonite (0, 2.5, 5, 7.5 and 10) wt% was added. The specimens were prepared by using the solid casting method, and after the drying process, the specimens were burned at 1100°C. The results of x-ray diffraction showed that bentonite reduced the crystallization of the main ceramic phases (mullite, quartz), which stimulates the appearance of amorphous glass phases. Also, the loss of mass on ignition increased when the addition of bentonite from 5.66% to 8.2%. There was also a great convergence between the granules of porcelain when adding bentonite and thus increase the shrinkage of the dimensions from 9.33% to 12.37%. This led to increasing the bulk density from 1.97 g/cm³ to 2.67 g/cm³ at firing temperature 1100°C, and the porosity was decreased from 17.1% to 1.44%. Diametrical strength and flexural strength (bending) increased with bentonite (14.88 to 34.46 MPa), (6.2 to 8.65 MPa), respectively.

This paper explores the concept of knowledge-based urban development (KBUD) and its impact on the growth of contemporary cities. KBUD is a strategic approach that integrates knowledge, innovation, and technology into urban planning and development to create sustainable and competitive cities. The study examines various case studies and theoretical frameworks to understand how KBUD can drive economic growth, improve quality of life, and enhance environmental sustainability in urban areas. The findings suggest that cities adopting KBUD strategies can achieve significant advancements in infrastructure, education, and social services, leading to overall urban prosperity.