DIYALA JOURNAL OF ENGINEERING SCIENCES

Switched Reluctance Generators (SRGs) have become quite popular lately because they offer some big advantages compared to regular generator technologies. This comprehensive review paper is dedicated to illuminating the latest developments in the realm of SRGs, offering a deep dive into their operational intricacies, diverse types, design principles, control strategies, versatile applications, and the formidable challenges that lay ahead. The paper begins by explaining in simple terms how Switched Reluctance Generators (SRGs) work and uncovering the main ideas that make them special and different from other generators. It then proceeds to categorize SRGs into various types, providing an insight into the diverse design features that distinguish them. This foundational understanding sets the stage for a more profound exploration of SRGs. The review focuses significantly on studying the complex control methods that manage SRGs, exploring the advanced techniques used to make them work better and more efficiently. As SRGs continue to evolve, their applicability spans a broad spectrum, ranging from clean energy generation to enhancing transportation systems and powering industrial machinery. This review carefully explains how SRGs can help change many different industries for the better. It shows how they have a lot of potential to make big improvements. Nevertheless, SRGs do not come without their share of challenges, encompassing issues related to efficiency, reliability, and the complexities inherent in control strategies. This review serves as an informative exploration of SRGs, highlighting their potential across various industries. It acknowledges their development and urges them to keep exploring their promising abilities. As switched reluctance generators become more popular, this discussion provides a detailed guide for those interested in understanding how they work and navigating their complex features.

Inverted and upright shell foundations, are increasingly utilized in engineering projects as structural elements beneath buildings, towers, curved dams, and other structures. They serve as economical alternatives to shallow foundations when encountering high loads transmitted through weak soil. The purpose of this research is to use the numerical modeling program Midas GTS NX to better understand the load-settlement behavior of inverted shell footings subjected to vertically applied loads. The study involved variables related to the properties of shell cross-sections, embedment depth of footing, and angle of side slope of footing. Also, the shell efficiency factor and the non-dimensional settlement factor for the shell footing are studied. The results show that inverted shell footings exhibit higher load-carrying capacity compared to traditional flat footings. Furthermore, it was found that inverted shell footings within the range of side slope angles of 15°–30° have a higher load-carrying capacity than traditional flat footings. Additionally, an increase in embedment depth was shown to be effective in enhancing the load-carrying capacity of inverted shell footings. From the obtained results, it was also concluded that the shell efficiency factor (η) of inverted shell footings is high. In particular, the inverted pyramid shell footing with an angle of 15°–30° exhibited higher efficiency compared to other footings, by 48.3% and 39.8%, respectively. The settlement improvement factor (Fa) of inverted shell footings was found to be low with the inverted pyramid shell footing at an angle of 15°–30° having a lower value compared to others by 5x10-4 and 507x10-4, respectively.

The study presents a comprehensive thermal performance analysis of a U-pipe Evacuated Tube Solar Collector (U-ETSC) system, integrated with Phase Change Material (PCM), for satisfying water demand in domestic applications. The innovative approach of incorporating PCM aims to enhance the system's efficiency during night or off-sunny hours, addressing a common limitation in solar heater systems. The research primarily focuses on the impact of varying mass flow rates of the heat transfer fluid (HTF) on the thermal dynamics of the system. Experimental results reveal that as the mass flow rates of HTF increase from 0.5 to 1 and then to 1.5 liters per minute, there is a notable change in the phase transition times of the PCM. Specifically, the melting time of the PCM is increased by 13% and 16% for the respective flow rates, suggesting a delayed response in energy absorption. Conversely, the solidification time of the PCM is reduced by 16% and 18% respectively, indicating a faster release of stored thermal energy. This behavior underscores the PCM's significant role in stabilizing the system's thermal output during varying solar intensities. The findings of this study highlight the potential of integrating PCM in U-ETSC systems to achieve a more consistent and reliable supply of hot water for domestic purposes, especially during periods when solar irradiance is low or absent.

Shape memory polymer (SMP) signify a new category of responsive polymers characterized by their capability to undergo significant shape changes and then revert to their initial shape when exposed to specific stimuli. They are known by their low mechanical properties; however, when integrated into fiber-reinforced composites a considerable characteristics enhancement is achieved. Modeling the thermomechanical behaviour of these materials is crucial task to understand their shape fixity and recovery. However, the available models in the literature are sophisticated and not easy to implement. In this study a simplified mathematical model is presented, based on the stimulus temperature-time relation, to determine the shape recovery action in a woven glass fiber (GF) reinforced styrene based SMP. The model is validated using experimental investigations done with DMA Q800 analyser and a specially designed bending recovery tool where a slight deviation of (8%-16%) was achieved. The model findings showed significant reduction in recovery time of 25% and 41% when the fiber content increased from 20% to 25% and 30%, respectively. This makes the proposed model a valuable tool for engineers to assess the shape memory behavior. Experimental findings indicated that fiber reinforcement led to a significant enhancement in thermomechanical properties represented by 5oC increase in glass transition temperature and five orders of increase in storage modulus. Also, a remarkable improvement in shape recovery rate of up to 80% is obtained, however there is a slight reduction of (8% - 16%) in the shape fixity property.

Electric demand in the last few years has widely increased, especially in Iraq, where there is a significant difference between the generation and the load in almost all months of the year, particularly in the summer season. One of the important aspects where the operational engineers must take appropriate action in case of an unforeseen catastrophe is power system security. Consequently, the security of the power system depends on the contingency analysis. In order to investigate the impact of wind power on the contingency analysis, three wind farms (WFs) are selected based on the wind's speed availability in Iraq, which are Shaikh Saad, Al-Dujaili, and Al-Fajar. In addition, the wind speeds for these locations are analysed using the Weibull and Rayleigh probability density functions. In this regard, this paper studied and analysed the impact of integrating wind power on the operation of the 132 kV Iraqi grid systems (zone 18). The results show that when line outage contingencies occur (single- and double-line outages), the risk of power flow violations based on the MVA rating will be reduced when integrating wind energy with a 100% integration rate with the Iraqi grid system. Matlab, a programming language, and the Power System Simulator for Engineering (PSS/E) software (Version 32) are used to simulate the proposed approach of integrating wind power into the grid.

Earthquakes are sudden and unpredictable natural activity that causes severe damage. As a result of the increasing seismic activity in Iraq, it has become necessary to conduct a study on the impact of earthquakes and methods of damping them. Since traditional seismic damping methods for construction are very expensive, alternative solutions are necessary. Therefore, this research proposes a new damping method that depends on surrounding the piles with rubber crumbs, as the rubber works to dampen the seismic force before it reaches the piles before moving to the structure. This method is considered a type of sustainability. The study included a set of variables, including (the thickness of the rubber that surrounds the piles, and the position of placing the rubber that sleeved the piles). The tests were carried out using the shaking table device. The results showed that surrounding the piles with rubber gave distinct results in damping the seismic force and it is considered an easy damping method due to its ease of implementation, as well as its economic feasibility. The results showed for the models that surround the rubber in the upper part of the pile, an increase in the values of the acceleration of the structure and a decrease in the values of the movement speed of the structure, the values of the lateral displacement of the structure. The models in which the rubber surrounds the middle and bottom part of the pile, the results were close to the reference model.

A reinforced concrete beam with shape memory alloy rebar (SMA) is a novel form of smart beam used in smart seismic structural systems to reduce the effects of earthquakes while keeping nearly the same load-carrying capability as conventional concrete beams. The experimental research investigation is carried out to study beams' flexural behavior by replacing some steel rebars with shape memory alloy rebars (SMAs) in the longitudinal reinforcement zone. The experimental program included testing three beams to investigate the effects of the replacement of longitudinal steel rebar by shape memory alloy rebar on the flexure behaviour of beams. The beams were tested by the repeated load. The study was focused on determining ultimate load, maximum deflection, and load-deflection behaviour. Experimentally, the flexure behaviour beams are significantly affected by changing the number of reinforcing bars with shape memory alloys (SMA) longitudinal direction. However, for using one rebar of shape memory alloy as a longitudinal reinforcement, the replacement of one bar and two bars of shape memory alloy SMA beams have less yield load than the control beam by about (12.5%) and (37.5%) respectively. The replacement of one bar and two bars of shape memory alloy SMA beams having less ultimate load compared with reference beam by about (9.82%) and (21.94%) respectively. Because of its superelasticity quality, the introduction of superelastic SMA bars to the beam shows excellent recentering ability.

Ocean energy represented by waves is considered as a one of the renewable energy sources. This study aims to evaluate the methods that enhancing the ocean wave energy convertor performance. The mechanism of wave energy convertor is by converting mechanical energy to an electricity energy using DC generator and running by the pulling of wire due to ocean wave movement. Moreover, the test and analyze of converting the wave energy to electricity are conducted. Firstly, the role of numerical modeling lies in fabricating the tested rig in addition to study and analyze the buoyancy and stability in fluid mechanics as results of converting the kinetic energy derived from sea waves into rotational energy. The experimental tests were achieved locally at the Arabic gulf-South of Iraq/Basra (Khor Alzubayr). the tests were performed in two cases named: after happening the tidal (tested in one direction) and at the increasing of the sea water (tested in bidirectional). The results of local tests (at the sea) show that the maximum power of test was recorded value about 68 W in case of happening the tidal with an increase percentage of 92.6% over the case of bidirectional. These findings encouraging for more investigation in the methods that could increase energy harvesting from ocean waves since it is an enormous amount of energy.

Gypseous soil is well-known for its numerous engineering problems. When this soil is exposed to water, the gypsum in the soil dissolves, causing the buildings built on it to collapse; so, treating gypseous soil is important for improving its engineering characteristics. The present paper focuses on studying the effect of adding geopolymer on mechanical characteristics of gypseous soil. This study presents the results obtained from a series of experimental tests, including direct shear, consolidation, and collapsibility tests. Tests were conducted on samples of gypseous soil taken from depth 1.5 meters below ground level with gypsum content of 41%. The geopolymer was used in three different molarities for the collapse test (10M, 12M, and 14M) and a 14 molarity only for the shear and consolidation tests, where equal proportions of fly ash were combined with an alkaline activator that was composed of sodium hydroxide and sodium silicate. The binder (fly ash + alkaline) to the soil was added to the treated samples during mixing at a rate of 20% by weight. The findings showed that treating the soil with geopolymer leads to a notable enhancement in the angle of internal friction of the soil particles from (37 to 42) degrees. as well as a reduction in the soil compressibility and a reduction in the susceptibility of the soil to collapse, with an improvement degree of 64% when using a geopolymer with a molarity of 14 M. This improvement was achieved by using a geopolymer with a higher concentration of NaOH. The best results were achieved when a geopolymer with a molarity of 14 was used, which is the ideal ratio.

This article includes an experimental investigation into the behavior of a vibratory force-exposed sheet pile set in sand. The study goal is to provide a parametric study. Regarding how vibrations affect the sheet pile's movement and rotation after layering the soil in a steel container with internal dimensions of 900 mm length, 400 mm wide and 400 mm high, a steel sheet pile with the dimensions of 350 mm length, 20 mm width and 0.5 mm thickness was inserted into the soil. The results showed that the speed, acceleration, and displacement increased with increasing the frequency of the vibration source when the source of vibration was situated at a distance of (D distance = H height of the sheet pile) and exposed to varied frequencies (5, 10, 15) Hz. As frequency is a type of energy, increased frequency will thus eventually cause more disturbance. The disturbance and its consequences on the soil will eventually increase as the frequency rises.

The main objective of this study is to experimentally determine the fatigue life of the aluminum alloys AA2014 and AA7075-T651 by measuring the lengths of short and long cracks practically under bending stress with constant amplitude loading and stress ratio (R = -1) at room temperature (RT) 25 C0 by employing Basquin's equation. To determine the fatigue life curve for both alloys at five different levels of constant amplitude stresses, the average failure cycles of three specimens at each stress level were recorded. The surface of specimen was replicated with cellulose paper and liquid acetone. This piece was examined using an optical microscope to record the length of the crack and the number of cycles corresponding to it at a constant stress level. The lengths of the cracks were then measured using the replication approach. A unique mathematical model was created to describe the relationship between crack speed (da/dN) and the length of short and long cracks in order to predict the overall fatigue life of each alloy. When the model's result was contrasted with actual outcomes, the conclusions were reliable and productive

The construction process is fraught with risks and uncertainties, which grow in proportion to the size and complexity of the project. The project is considered successful if it is completed within the specified time and cost and with the required quality standards. The time and cost overrun of building projects and highways is a critical issue because of the great risks that result from it, which affect the project completion process and sometimes put it to a halt. In this paper, an attempt was made to predict the final cost rate and final time rate of such projects before starting work, using the technique of reverse elimination regression analysis. The study covers a group of highway projects in Diyala Governorate, where the records of (25) projects that were completed during (2012-2021) were used to develop and validate the regression model. Based on the experts' convictions, there are nine factors that are considered the most influential on the final cost and final time. Hence they are used as input parameters for the form. These factors are; bid cost, bid duration, change order cost, change order duration, final cost, and final duration, no. of change order, start time and final time. It was found that the developed regression model has the ability to predict the final cost rate (FCR) and final duration rate (FDR) for highway projects as outputs with very high goodness of fit and coefficient determination ( ) of (98%) and (96%) for FCR and FDR respective.