Tikrit Journal of Engineering Sciences

Surface roughness of machined parts has significant effect on the final part quality which can affect its tolerance and performance. In this work the effect of turning machining operation on surface roughness of AISI 1045 steel using TiN coated carbide insert was investigated. Two different machining parameters with nine variable samples, including different spindle speeds and feed rates, were selected to study the resultant surface finish of the steel samples. The results showed that the lowest Ra value of 4.14 was obtained by using a feed rate of 50 mm/min with a spindle speed of 355 rpm, while the highest surface roughness value of 7.9 was obtained by using a feed rate of 160 mm/min at a spindle speed of 710 rpm. In general, it could be observed that higher spindle speeds resulted in higher Ra, while lower speeds results in lower Ra. The current study provides a good understanding of the effect of turning operation on surface roughness which can be used as a basis to develop a regression model to generate the optimum cutting parameters for turning operations.

The present work is especially concerned with the Iraqi bauxite ore that includes 4.1% of titanium element (Ti). The goal of this study is to investigate the effect of various parameters (concentration of acid, ratio of solid: liquid, stirring speed, contact time, and temperature) in order to determine the best conditions for the leaching and extraction of titanium element. All tests of leaching were conducted with different acids (HNO3, H2SO4, and H3PO4) with a ratio of solid: liquid from (1: 100) to (1: 8), the temperature of reaction from (25°C) to (50°C), period of time from (30 min) to (120 min), and speed of stirring from (400 rpm) to (1200 rpm). The best conditions were determined at (1: 100) solid: liquid ratio, (50°C) temperature, (4 M) HNO3 concentration, and (900 rpm) stirring speed. While, the titanium extraction was from leached solution by (trioctylphosphine oxide) (TOPO), tri-n-butyl phosphate (TBP), and di-2- ethylhexyl phosphoric acid (D2EHPA) dissolved in kerosene) with an organic/aqueous ratio of (1/1, 1/2, 1/3, 2/1, and 3/1); temperature of reaction and period of time are correspondingly from (25°C) to (55°C) and from (8 min) to (15 min), and speed of stirring (400 rpm). The best conditions were obtained when using (55°C) temperature, (50%) TOPO concentration, (15 min) contact time, (400 rpm) speed of stirring and (1/3) O/A ratio.

Gypseous soil, as is well known, includes a specific quantity of gypsum. Gypsum is a water-soluble salt with a solubility of (2.2-2.6) gram/liter in distilled - water. As a result, the presence of gypsum poses a challenge when building structures on this soil, since gypsum dissolves when exposed to water, producing gaps between soil particles and so causing soil collapse. This study examines the behavior of a shallow foundation rested on gypseous soil. Three types of gypseous soil with gypsum contents of (61%, 45.3%, and 27.9%, respectively) are used, and treated with ceramic wastes, which is a waste product of construction. The Soil samples were collected from the site of Tikrit University's campus. The study consists of six test cases, two for each type of soil, one dry and the other wet, where the first test for each case was used as a baseline for comparison, which was the soil test without the addition of ceramic wastes, and the rest was added in three proportions (3%, 6%, and 9%) and three mixing depths for each ratio (B/2, B, 3B/2).The percentage 9% ceramic wastes gives best results of improving, the bearing capacity of the soil improved by 233%, 256 %, and 289% for high gypseous soil, and by 78%, 94%, and 111% for medium gypseous soil, with a percentage of 60%, 87%, and 113% for low gypseous soils. Adding ceramic wastes to wet gypseous soil improves the bearing strength of the soil, lowers settlement to some extent, and reduces the influence of water on it.

Acid rain is any precipitation with a very low pH, whereas normal rain water is slightly acidic with a pH range of 5-6, but the pH level of rain water falls below this range, becoming acid rain. It happens as a result of wet and dry deposition from the atmosphere of chemical pollutants emitted by various human activities. Dry deposition is more frequent and effective than wet deposition. It was found that the leading cause of acid rain is the emission of gaseous oxides of sulfur, nitrogen and carbon. These environmental pollutants come from various human activities such as the burning of fossil fuels, combustible waste, vehicle exhausts, thermal power projects, the combustion of vegetation and wastes of wars. These chemical pollutants interact with different precipitation such as; rain, cloud, fog and snow water, which is formed in the case of sulfuric, nitric and carbonic acids, then shows its impact on the lithosphere, water and atmosphere, in addition to its impact on other ecosystems such as; Forests, agricultural crops, soil, buildings and aquatic organisms, as well as human health. The risk of acid rain is controlled by reducing the emissions of gases to neutralize acidity which requires enacting laws and do enforce efforts to reduce pollution and control acid rain on all production projects. Our current study aims to assess the acidity of the rainwater, and it has been proven that the relative pH of the rainwater in the city of Mosul has decreased in the past two years (2020/2021-2021/2022) from (6.5 to 5.8), which requires knowing its causes, effects, and methods to limiting its consequences.

The fiber-reinforced polymer (FRP) wrapping is widely used in concrete column strengthening, as it can enhance concrete strength and ductility. This study aims to develop finite element numerical model that can capture the behavior of the short cylinder column confined with CFRP. After validating the proposed finite element models with previous experimental works, a series of parametric studies have been conducted, including, CFRP number of layers, concrete grade, confinement configuration, and size of samples are investigated in terms of stress-strain curves, ductility, and volumetric strain. The results indicate a significant improvement in concrete strength after fully CFRP wrapping. However, the partial confinement records less improvement in concrete strength but considerable ductility. By increasing the specimen’s size and maintaining the same confinement ratio, the strength enhancement was decreased. Based on this observation; it can be concluded that; by increasing the samples sizes, it should be escorted with more confining ratio than that of the small size. Moreover, it was concluded that as the number of layers increases the ductility increases whether it was full or partial confinement configuration. The CFRP confinement can control the specimen’s dilation during the axial compression test thus presenting less volumetric strain. The proposed formula by (Lam & Teng, 2003) that can predict the stress-strain response of FRP full confined concrete cylinder was compared with the corresponding values. The results indicated that; a good matching was noticed only for the samples located in the same area that was studied by (Lam & Teng, 2003).

As the number of smartphone users grows, the smartphone's function in healthcare has evolved from a device that is used to arrange doctor appointments via the internet rather than the traditional approach. Mobile apps are a convenient way to track and collect data in order to combat the spread of COVID-19. To ensure that the right to privacy and civil liberties are maintained, we report on our investigation of 50 COVID -19- related apps, including their access to and use of personally identifiable information. Reservations are made at the doctor over the Internet, and an appointment is arranged for the visit and medical examination at a certain time, resulting in a reduction in the spread of the virus, especially in pandemic conditions such as Covid-19. Additionally, this provides a service for saving data and health files in the cloud on the Internet to retrieve information when needed, and not wasting these files and health papers while providing protection for them in terms of patient privacy. Designing an application (App) functioning on IOS and Android systems which works in mobile devices easily to provide the ability to book a doctor appointment from App. The App is a link between the patient and the doctor to reduce the patient’s presence in health centers and medical facilities which are good centers for transmission of infection, especially in COVID-19. During the design of app, we have considered the low speed of data throughput especially for IRAQ.

Heat transfer augmentation for Taylor-Couette flows between concentric cylinders have been investigated experimentally. Due to its importance and widespread in wide industrial applications such as heat exchangers, reactors, well dinning, packed beds, compressors and gas turbines, chemical industries, etc. Different variables are investigated in the present work as follow, Rayleigh number (2×106 ≤ Ra ≤ 2×107), Taylors number (0 ≤ Ta ≤ 2.4×1010), Richardson Number (0.004 ≤ Ri ≤ 0.4) and nanoparticles volume fractions(φ) of Al2O3 with water base (0 % ≤ φ ≤ 0.225 %) in which prepared in two step method. The enhancement in heat transfer was 16.5% to 24% due to rising the concentration of Nano fluids of Al2O3-pure water from 0% to 0.225%. Also, the Nusselt number increases with increasing Rayleigh and Richardson numbers. Finally, a correlation was deduced to describe the experimental work and linked the studied parameters with difference less than 13.5 %. The comparison between experimental work and previous works found a good agreement between them.

Proper dam management should be ensured regularly to avoid breaches and failure. In this study, the finite element method was used to analyse the stability of the Shirin earthen dam under various conditions. The necessary laboratory tests for soils used in the construction of the dam were carried out in the laboratories of the College of the Engineering /University of Tikrit, and these data were employed in the GEO-STUDIO program to analyse the seepage and stability of the dam. The seepage was analysed at three levels of the water lake reservoir including the highest, middle and lowest water levels. In addition, factors such as the permeability of the shell layer, the presence and thickness of the dam’s core layer, the placement of filters at the back of the dam and the exit gradient have been considered. The results have shown that by increasing the permeability of the shell layer, the exit gradient is decreased while the seepage through the dam body is increased. The presence of the dam’s core layer has a significant effect on reducing the amount of seepage through the dam’s body as the amount of seepage is reduced by (99%). Moreover, it was found that the minimum safety factor is 1.95 and it occurs after (4 days) of the rapid emptying of the reservoir, and this indicates that the upstream slope of the dams is safe during water emptying.

The goal of this research was to determine the impact of a pooled and flat stepped spillway on energy losses. FLOW3D, which is a computational fluid dynamics (CFD) program, with mesh size of 0.015 mm was used for this purpose. First, the code was tested against an available experimental model data for both water flow depth and inception point position. The outcome precisely shows agreement with the available laboratory work. Second, the energy dissipation and residual head of two different types of stepped spillways, flat and pool was computationally compared. The results show that in a pooled stepped spillway, energy dissipation is larger than in a flat step. In addition, the residual head reduces for pooled stepped chutes.