Journal of Engineering

Solar photovoltaic (PV) systems have emerged as one of the most promising technologies to generate clean energy. This work studies the performance of monocrystalline silicon photovoltaic modules by observing the effect of necessary parameters: solar irradiation and ambient temperature. The single diode model with series resistors is selected to find the characterization of current-voltage (I-V) and power-voltage (P-V) curves by determining the values of five parameters. This model shows high accuracy in modeling the solar PV module under various weather conditions. The modeling is simulated using MATLAB/Simulink software. The performance of the selected solar PV module is tested experimentally for different weather data (solar irradiance and ambient temperature) gathered from October 2017 to April 2018 in the city of Baghdad. The collected data is recorded for the entire months during the time limited between 8:00 AM and 1:00 PM. This work demonstrates that the change in cell temperature is directly proportional to the PV module current, while it is inversely proportional to the PV module voltage. Additionally, the output power of a PV module increases with decreasing the solar module temperature. Furthermore, the Simulink block diagram is used to evaluate the influence of weather factors on the PV module temperature by connecting to the MATLAB code. The best value from the results of this work was in March when the solar irradiance was equal to 1000 W/m² and the results were: Isc,exp = 3.015, Isc,mod = 3.25, RE = 7.79 and Voc,exp = 19.67, Voc,mod = 19.9, RE = 1.1.

In developing countries, conventional physico-chemical methods are commonly used for removing contaminants. These methods are not efficient and very costly. However, a new in-site strategy with high treatment efficiency and low operation cost named constructed wetland (CW) has been set. In this study, Phragmites australis was used with a free surface batch system to estimate its ability to remediate total petroleum hydrocarbons (TPH) and chemical oxygen demand (COD) from Al-Daura refinery wastewater. The system operated in semi-batch mode, with new wastewater added weekly to the plant for 42 days. The results showed high removal percentages of 98% for TPH and 62.3% for COD. Additionally, Phragmites australis biomass increased significantly during the experiment period, with a 60% increase in wet weight. These results proved the ability of Phragmites australis to tolerate a contaminant environment and enhance the biodegradation of TPH. Two kinetic models were used, and the pseudo-second-order model was fitted to the data with an R² of 0.999.

The efficient removal of dissolved organic compounds (DOC) from wastewater has become a major environmental concern due to their high toxicity even at low concentrations. This study investigates the use of ion exchange technology (IE) with Amberlite TM IR120 Na, Amberlite TM IR96RF, and Amberlite TM IR402 to reduce these pollutants. The process of adsorption was examined using an anion and mixed bed system, considering variables such as bed height in the column (8, 10, and 14 cm) and different DOC concentrations at a constant flow rate. The study also explored the use of a continuous ion exchanger unit with three columns (cation, anion, and mixed bed) and the effects of temperature changes (23, 30, and 40°C) and flow rate variations (2, 4, 6 L/min). The results showed that adsorption capacity decreased with increasing flow rate. The Langmuir model was found to be the most consistent with the adsorption results, having the highest adsorption capacity and correlation value (R² = 0.97). The ion exchange column dynamics were studied using models such as the Thomas model, and the experimental results were well correlated with the model equations. The removal rate of pollutants was up to 90% for organic compounds.

Large quantities of contaminated carwash wastewater are produced per day from carwash places. Extensively it contains large quantities of chemicals from detergents, oil, grease, heavy metals, suspended solids, types of hydrocarbons, and biological contents. A novel electrocoagulation treatment by foil electrodes was conducted to remove COD, turbidity, Total Dissolved Solids (TDS) from contaminated carwash wastewater and decrease its Electrical Conductivity (EC). A thin layer of aluminum foil is used as an electrode in this treatment process. The effects of different voltage and treatment times were studied. The best result was found at a voltage of 30 volts and treatment time 90 minutes where the removal efficiency of COD, turbidity, TDS, and EC were 97.94%, 99.90%, 25.31%, and 15.57% respectively.

Sewer systems play an essential role in urban cities by protecting public health and the environment. The operation, maintenance, and rehabilitation of these networks must be sustainable and scientifically sound. This paper employs serviceability and performance indicator (PI) principles to propose a methodology comprising two enhanced PI curves that can be used to evaluate individual sewers based on operational factors such as flowing velocity and wastewater level in the sewers. A case study of Al-Rusafa in Baghdad city is presented, where two combined trunk sewers (Zeblin and ET-trunks) are analyzed. Hydraulic analysis for two scenarios (average and peak dry weather flows) is performed, and performance evaluation shows a sub-index ranging from 0.5 (minimum level of performance) to 1 (excellent performance). This indicates that these two trunks, if well maintained, will provide sufficient service to the catchment. By applying the serviceability and PI principles, a prioritizing tool is provided to help decision-makers better manage the sewerage system.

The assessment of river water quality is an essential procedure for monitoring programs and is used to collect basic environmental data. The management of integrated water resources in a sustainable method is also necessary to allow future generations to meet their water needs. The main objective of this research is to assess the effect of the Diyala River on Tigris River water quality using Geographic Information System (GIS) technique. Water samples have been collected monthly from November 2017 to April 2018 from four selected locations in Tigris and Diyala Rivers using the grab sampling method. Fourteen parameters were studied, including Turbidity, pH, Dissolved Oxygen, Biological Oxygen Demand, Electrical Conductivity, Total Dissolved Solids, Total Hardness, Calcium, Magnesium, Chloride, Sulphate, Phosphate, Sodium, and Total Alkalinity. The results of GIS maps showed that the water quality of the Tigris River was nearly affected by the water quality of the Diyala River within the selected locations. The maps also revealed that in March and April 2018, the quality of surface water experienced a sudden peak compared with other months, due to the increase in both Turbidity and Total Dissolved Solids.

Nowadays, the use of recycled waste construction materials instead of aggregates is becoming popular in construction owing to its environmental benefits. This paper presents an experimental and analytical campaign to study the behavior of axially loaded columns constructed from recycled aggregates. The latter was used instead of natural aggregates, and they were collected from the waste of previous concrete constructions. Different concrete mixtures made from varying amounts of recycled aggregates ranged from 0 to 50% of the total coarse aggregate were conducted to achieve 28 MPa. The effect of steel fibers is another investigated variable with volumes ranged from 0 to 2% concerning concrete’s mixture. The experimental results showed that the concrete strength is dependent on the amount of recycled aggregates. When the recycled aggregates were less than 30% of the total aggregates, they had a negligible effect on concrete strength and the load carrying capacity of the column models were improved. Also, the presence of steel fibers enhanced the load carrying capacity of the columns constructed from concrete with recycled aggregates of more than 30%. Finite element analysis (using ANSYS 16.1 software program) was conducted to simulate the experimental investigations, and they achieved good agreements with the test results

In recent years, the Global Navigation Satellite Services (GNSS) technology has been frequently employed for monitoring the Earth crust deformation and movement. Such applications necessitate high positional accuracy that can be achieved through processing GPS/GNSS data with scientific software such as BERENSE, GAMIT, and GIPSY-OSIS. Nevertheless, these scientific softwares are sophisticated and have not been published as free open source software. Therefore, this study has been conducted to evaluate an alternative solution, GNSS online processing services, which may obtain this privilege freely. In this study, eight years of GNSS raw data for TEHN station, which located in Iran, have been downloaded from UNAVCO website on a daily basis. Furthermore, TEHN GNSS observations are processed with CSRS-PPP, which is based on Precise Point Positioning (PPP) algorithm, and OPUS, which is based on double difference (DD) algorithm, to compare between these two techniques in terms of station velocity estimation and Earth deformation. On the other hand, TEHN station solutions that produce via scientific software, GIPSY-OSIS, are obtained from Nevada Geodetic Laboratory (NGL) website for data validation. Eventually, the results show that both GNSS online processing services (CSRS-PPP and OPUS) are credibly efficient to estimate station velocities, while CSRS-PPP trustworthy service for monitoring the Earth deformation.

The regression analysis process is used to study and predict the surface response by using the design of experiment (DOE) as well as roughness calculation through developing a mathematical model. In this study, response surface methodology and the particular solution technique are used. Design of experiment used a series of the structured statistical analytic approach to investigate the relationship between some parameters and their responses. Surface roughness is one of the important parameters which play an important role. Also, it was found that the cutting speed can result in small effects on surface roughness. This work focuses on all considerations to make interaction between the parameters (position of influence) because laser power directly depends on cutting speed with high gas pressure and vice versa to obtain a less surface roughness. Data analysis showed that the lower value for roughness was 0.68 μm and the high roughness was 8.56 μm. The model values for considered fit are suggested to be as R² = 51.76%. The selected coefficient is referred to the amount of model variation in the response. The adjusted value of R² = 8.34% will calculate the number of forecasting model and is normally useful for comparing models with different numbers of predictions. The F test is used to determine whether interaction and major effects are significant. The p-value is the probability of obtaining a statistic test which is considered as the extreme of actual calculated values if the null hypothesis is true. A commonly cut-off value that used for the p-value is 0.05. This value is used to be the active contribution to investigate the correlation between laser machining parameter with the surface roughness. Also, the goal of this research highlights the experimental control parameters of mild steel laser processing with their responses.

This study investigates the effect of lacing reinforcement on the performance of reinforced concrete beams under static and fatigue loads. Twelve reinforced concrete beams, including two control beams with vertical shear reinforcement, were tested under four-point bending loading with displacement control. Six laced reinforced concrete beams were exposed to high-frequency fatigue loading (10 Hz) by fixing the fatigue load in each cycle. The parameters studied included lacing bar diameter (4mm, 6mm, and 8mm), lacing bar inclination angle to horizontal (30°, 45°, and 60°), and lacing steel ratio depending on the number of lacing bars in each longitudinal face of the beam and lacing bar diameter. The experimental results revealed that the ultimate loads of laced reinforced concrete beams were higher than those of conventional reinforced concrete beams due to the increased lacing bar diameter, angle of inclination, and lacing steel ratio, while the deflection was reduced. The laced reinforced concrete beams demonstrated improved performance under both static and fatigue loading conditions.

In this study, the generation of elliptical gears with different teeth profiles of crowned involute, double circular arc (DCA), and combined (crowned involute with DCA) has been developed. The resulting mathematical equations have been computerized and fed to a CNC end mill machine to manufacture elliptical gear models with different profiles. These models are investigated in a plane polariscope to show the resulting stresses under certain loads. Comparison of photo-elastic stress results shows that combined elliptical gears with DCA side as a loaded side have a minimum resulting contact stress with a reduction percentage of 40% compared with contact stresses in counterpart elliptical gear of involute profile (which is commonly used in several applications). In this case, bending tooth stress reduction is 47.05% compared with involute elliptical gear. While the reduction in bending stresses of combined elliptical gear becomes higher (52.94% lower than involute gear) when crowned involute side is the loaded side, but the contact stress reduction in this case becomes lower (20% relative to involute gear). Maximum reduction in bending stress can be obtained when a single profile of DCA type is used with a reduction of 64.7% relative to involute gear. Therefore, when the application requires high contact stress resistance, combined profile can be used with DCA side as a loaded side. While in the applications that require high bending stress resistance, DCA profile can be used.