Journal of Engineering

The influence of adding metal foam fins on the heat transfer characteristics of an air-to-water double pipe heat exchanger is numerically investigated. The hot fluid is water which flows in the inner cylinder whereas the cold fluid is air which circulates in the annular gap in parallel flow with water. Ten fins of metal foam (Porosity = 0.93) are added in the gap between the two cylinders and distributed periodically with the axial distance. The finite volume method is used to solve the governing equations in porous and non-porous regions. The numerical investigations cover three values for Reynolds number (1000, 1500, 2000) and Darcy number (1 x10^-1, 1 x10^-2, 1x10^-3). The comparison between the two cases with and without insertion of the metal foam fins is examined in this study. Results show that the temperature of the inner pipe wall is affected by the Reynolds number, water inlet temperature, and Darcy number variation. The resulting values and the behavior of the local and average coefficient of heat transfer are presented. The improvement in the mean coefficient of heat transfer (h_m) is found to be 129% with the use of the metal foam fins.

This research presents a study for precipitating phosphorus (as phosphate ion) from simulated wastewater (5ppm initial concentration of phosphorus) using calcium hydroxide Ca(OH)₂ solution. The removal of phosphorus by Ca(OH)₂ solution is expected to be very effective since the chemical reaction is of acid-base type but Ca(OH)₂ forms a complex compound with phosphate ions called hydroxyapatite Ca₅(PO₄)₃OH, which is slightly soluble in water. The study investigates the kinetics of the dissolution reaction of hydroxyapatite to find the best factors for recovering phosphorus. The effect of Ca(OH)₂ concentration (180-380 ppm) on phosphorus precipitation, residual phosphorus concentration, percentage removal, and precipitate weight was studied. The best Ca(OH)₂ concentration was found to be 230 ppm at a fixed mixing speed of 400 rpm and a temperature of 20°C. The study also applied the best concentration to real wastewater from a detergent factory, achieving a 30.69% removal rate. Oxalic acid was chosen to dissolve hydroxyapatite due to its lower hazard and cost compared to mineral acids. The kinetics of the dissolution reaction of hydroxyapatite in 160 ppm oxalic acid under ambient conditions (20°C, 1 atm, 200 rpm) was studied, revealing a reaction order of 0.4296 and a rate constant of 0.0743 (L/mg)^-0.5704 min^-1.

A 3D geological model was constructed for Al-Sadi reservoir in the Halfaya Oil Field, discovered in 1976 and located 35 km from Amara city, southern Iraq, near the Iraqi/Iranian borders. Petrel 2014 software was used to build the geological model based on available information such as 2D seismic maps, top and bottom of wells, geological data, and well log analysis (CPI). The reservoir was subdivided into 132x117x80 grid cells in the X, Y, and Z directions to represent the entire Al-Sadi reservoir accurately. Well log interpretation (CPI) and core data from six wells were used to create the petrophysical model (porosity, water saturation, and permeability), which was then distributed across all grid cells and upscaled.

A new technique in cultivation by installing a membrane sheet below the crop’s root zone was used to save irrigation water in the root zone, reduce farm losses, and increase field water use efficiency and water productivity. This research was conducted in a private field in Babil governorate at Sadat Al Hindiya Township, 72 km from Baghdad, during the summer growing season of 2017. A surface trickle irrigation system was used for the irrigation process. Two treatment plots were used: treatment plot T1 with a membrane sheet and treatment plot T2 without a membrane sheet. The applied irrigation water, time of irrigation, and soil moisture contents before irrigation were calculated and recorded daily for both treatment plots. The results indicated that field water use efficiency for plots T1 and T2 were 6.04 and 4.64 kg/m³, respectively. The increase in field water use efficiency (FWUE) of plot T1 compared to plot T2 was 30.2%. Additionally, the economic water productivity of zucchini for plots T1 and T2 was 20514.1 and 15031.7 ID/m³, respectively. The increase in economic water productivity (EWP) of plot T1 compared to plot T2 was 36.5%. The water saving in plot T1 was 16.7%, and the reduction in irrigation frequency at T1 was 12%.

Drastic threat to the natural system is caused by the uncontrolled release of synthetic pollutants, including azo dyes. This study centered on the decolorization and biodegradation of water-soluble azo dye reactive blue (RB) in a batch mode sequential anaerobic-aerobic processes. A local sewage treatment plant was the source where activated sludge was collected to be used as non-adapted mixed culture with both free and the alginate immobilized cells for RB biodegradation. Under anaerobic conditions, the free and immobilized mixed cells were proved to completely decolorize 10 mg/L of RB within 20 and 30 hours, respectively. Alginate-immobilized mixed cells resulted in 88%, 87%, and 87% maximum COD removals with samples containing RB at initial concentrations of 10, 20, and 40 mg/L, respectively. UV-vis spectra showed the biological cleavage of the azo bond in the anaerobic phase. Estimation of the phytotoxicity of the degraded metabolites suggested that the non-adapted immobilized mixed bacterial cells successfully detoxified RB azo dye.

With the wide applications of wireless sensor networks (WSN), securing its data becomes a requirement. This can be accomplished by encrypting sensor node data. In this paper, a new and efficient symmetric cryptographic algorithm is presented. This algorithm is called the Wireless Sensor Network Wavelet Curve Ciphering System (WSN-WCCS). The algorithm is based on discrete wavelet transformation to generate keys for each node in WSN. It is implemented on hierarchical clustering WSN using the LEACH protocol. Python programming language version 2.7 was used to create the simulator of the WSN framework and implement the WSN-WCCS algorithm. The simulation results of the proposed WSN-WCCS with other symmetric algorithms have shown that its execution time is faster than AES, 3DES, and DES by 15%, 55%, and 17%, respectively.

In general, the path-planning problem is one of the most important tasks in the field of robotics. This paper describes the path-planning problem of mobile robots based on various metaheuristic algorithms. The suitable collision-free path of a robot must satisfy certain optimization criteria such as feasibility, minimum path length, safety, and smoothness. In this research, three approaches, namely PSO, Firefly, and the proposed hybrid FFCPSO, are applied in a static, known environment to solve the global path-planning problem in three cases. The first case used a single mobile robot, the second case used three independent mobile robots, and the third case applied three follow-up mobile robots. Simulation results, carried out using MATLAB 2014 environment, show the validity of the kinematic model for Nonholonomic mobile robots and demonstrate that the proposed algorithm performs better than the original PSO and FF algorithms under the same environmental constraints by providing smooth velocity and the shortest path for each mobile robot.

Implementation of Warm Mix Asphalt concrete (WMA) is gaining global acceptance due to environmental restrictions and the need to reduce fuel consumption. In this investigation, two WMA mixtures were prepared in the laboratory using medium curing cutback (MC-30) and Cationic emulsion asphalt. Hot Mix Asphalt (HMA) was also prepared for comparison. Cylinder specimens (63.5mm in height and 101.6mm in diameter) were constructed from the mixtures and subjected to indirect tensile strength tests to determine the Tensile Strength Ratio (TSR). Additional cylinder specimens (101.6mm in height and 101.6mm in diameter) were constructed and subjected to static compressive strength tests to determine the Index of Retained Strength (IRS). The study concluded that WMA is more prone to moisture damage than HMA. The TSR values for emulsion and cutback WMA were 92% and 86%, respectively, both lower than HMA by 2.13% and 8.51%, respectively. As asphalt content increases, TSR also increases, reaching a peak value at Optimum Asphalt Content (OAC) before decreasing. WMA has a lower IRS than HMA, with IRS values of 70% for WMA-emulsified asphalt and 78% for HMA.

Despite the long history of Baghdad, most contemporary buildings in the city have been shaped during the era of modernity. These buildings, which represent the identity of Baghdad, should be preserved through renewal and preservation policies. However, after 2003, new finishing materials unrelated to the notion of modernity have been used to cover their exterior facades. This research highlights this phenomenon and analyzes the effects of using these materials, specifically aluminum plates, on the facades of buildings constructed between the 1950s and 1960s. The study aims to identify the reasons for using such materials and suggest recommendations to address their negative impacts.