Journal of Engineering

This paper presents an experimental study on the thermal performance of an aluminum foil coated with polyester in a direct evaporative cooling system. The study investigates the effect of using this new cooling medium on the wet-bulb temperature (WBT), dry-bulb temperature (DBT), relative humidity (RH), and air flow rate. The experimental setup included varying the air flow rate (300-600 CFM) and water flow rate (1.75, 2.5, 4.5 LPM). The results showed a decrease in WBT and DBT, with the WBT of the air entering the pad at 26.5°C and the WBT of the outside air at 23°C. The DBT of the air entering the pad was 45°C, while the DBT of the outside air reached 29°C. The relative humidity of the air supplied from the pad was 57%RH, which is lower compared to conventional pads, indicating better moisture-carrying capacity.

This paper presents experimental measurements for characterizing the current-voltage (I-V) and power-voltage (P-V) curves of two types of photovoltaic (PV) solar modules: monocrystalline silicon (mc-Si) and copper indium gallium di-selenide (CIGS). The conversion efficiency of these modules depends on factors such as irradiation and temperature. The assembling process often causes variations in electrical boundaries, even among cells of the same type. Additionally, losses due to cell connections in a module make it difficult to find two identical photovoltaic modules. Therefore, only the I-V and P-V curves' experimental measurements allow for accurate determination of the electrical parameters of a photovoltaic device. This information is crucial for the design, installation, and maintenance of PV systems. Three methods—simplified explicit, slope, and iterative—are used to compute the parameters of two solar models using MATLAB code. The percentage maximum power errors at 600 and 1000 W/m² for both current-voltage and power-voltage values with the corresponding measured ones using the slope method are 0.5% and 3% for mc-Si and CIGS, respectively. The iterative method shows errors of 5% and 10%, while the simplified explicit method shows errors of 8% and 9%, respectively. The slope method provides results closest to the measured values for both PV solar modules, making it less influenced by meteorological conditions.

his paper addresses the twin crises of fossil fuel depletion and environmental degradation by exploring biodiesel production from renewable feedstocks such as Jatropha seed oil through transesterification. The study involved extracting and analyzing Jatropha curcas seed oil to determine its free fatty acid and fatty acid composition1. The oil was then transesterified with methanol at a molar ratio of 8:1, using a 1% sodium hydroxide catalyst, at temperatures ranging from 32°C to 65°C, at atmospheric pressure. The reaction kinetics were studied, revealing that the disappearance of triglycerides followed a pseudo-first-order reaction at the chosen temperatures and a first-order reaction at 32°C1. The rate constants for the consecutive reaction steps at 65°C were found to be 0.422 min⁻¹, 0.117 min⁻¹, and 0.037 min⁻¹ for triglyceride to diglyceride, diglyceride to monoglyceride, and monoglyceride to glycerol, respectively. The corresponding activation energies were 22.165 J/mol, 3.136 J/mol, and 19.770 J/mol, respectively1.

This paper investigates the water distribution in surface drip irrigation systems considering root water uptake using different soil hydraulic models. The study utilized HYDRUS-2D software (version 2.04) to simulate the wetting pattern in unsaturated soils for two soil types (sandy loam and clay loam) and three plant types (corn, tomato, and sweet sorghum). The soil wetting pattern was analyzed every 30 minutes for three hours of irrigation time and three initial soil moisture content levels. Equations for wetted radius and wetted depth were predicted and evaluated using statistical parameters such as Model Efficiency (EF) and Root Mean Squares Error (RMSE). The results showed that the RMSE values did not exceed 0.40 cm, and EF was greater than 0.96 for all soil types, indicating good agreement between the HYDRUS-2D results and the evolved formulas. The relative error for different hydraulic soil models was calculated and compared with Brooks and Corey's model (1964), showing good agreement with an RMSE of 0.23 cm and relative error within -1% to 1% for EF.

This paper explores the diffusion of innovation into architectural movements. The complexity of the architectural field compared to other fields presents a challenge in explaining how innovations in architecture spread as ideas and actions within a specific context of practice. The research aims to build an intellectual model that explains how personal thoughts, represented by unique models introduced by creative and innovative designers, diffuse in a certain pattern and elaborate these models into a prevailing thought resembling a movement in architecture. The study applies its model to a comprehensive architectural movement, defining the roles of innovators over time. With continuity, the innovative models developed into styles and currents within a major thought, elaborating into a "movement" leading architectural practice, framing its aesthetic and spatial preferences.

This study analyzes the effluent quality parameters of the new Maaymyrh sewage treatment plant in Hilla city using statistical methods such as Principal Component Analysis (PCA) and Cluster Analysis (CA). The plant serves a population of 500,000 and operates on a biological treatment method (Activated Sludge Process) with an average wastewater inflow of 107,000 m³/day. Data were collected daily from November 2019 to June 2020 for parameters including BOD5, COD, TSS, TP, and TN. The results showed removal efficiencies of 88%, 75%, 94%, 57%, and 77%, respectively. PCA extracted two influencing factors, while CA formed clusters in four stages, ultimately resulting in two groups. The final effluent quality met stringent Iraqi regulations over an average of eight consecutive months.

This paper investigates the behavior of defective cast-in-place piles through experimental work. The study evaluates the general behavior of defective piles by examining two parameters: defect location and defect type for floating and end-bearing piles. The results indicate that the critical case for floating piles occurs when the defect is 5% at the first third of the pile length, resulting in a 21% decrease in bearing capacity. For defects at the middle and lower third of the pile length, the decrease in bearing capacity is 14% and 10%, respectively. For floating piles, the decrease in bearing capacity is 31% for void defects and 21% for neck defects. For end-bearing piles, the decrease in bearing capacity is 43% for void defects and 52% for neck defects.