Tikrit Journal of Engineering Sciences

Electric discharge machining (EDM) is considered one of the most energy-efficient production methods for the highly accurate processing of any electrically conductive materials, regardless of mechanical characteristics. EDM is a non-contact method used in a diverse range of industries, including aerospace, industrial, instruments, molds and dies, and medical tools, particularly for hard materials with simple or intricate geometries and shapes. This review investigated EDM research in process, material, operational parameter selection, the influence on outputs, numerous process varieties, and innovative strategies to improve performance. The present study presented an overview of the EDM process with different angled electrode geometry, optimization, and modeling of method parameters, and the effect of parameters such as material removal rate (MRR), pulse shape, and surface roughness. This review (1) organized the published literature in a specific way, with an emphasis on both theoretical and experimental findings investigations to enhance the process performance, such as the rate of material removal and quality of surface, among others, and tool wear; (2) investigated assessment methods and procedures used to evaluate process circumstances; and (3) examined the EDM improvements and predicted future trends study. The article's conclusion section extracts specific points and gaps in each part. As a result, the article is straightforward to comprehend and incredibly beneficial to the scientific community.

For environmental and economic purposes, it is necessary to search for methods that reduce gas emission by flare from the oil refineries. It causes environmental pollution and warmup. All laboratory tests have been completed at Koya University, with the contribution of the Institute of Technology in Koya, to check some readings and verify their accuracy. Increasing the absorptivity of the gases by heavy oil will have expected to improve oil burning characteristics. This research aims to determine the best operating conditions that leads for higher absorption. In this research the diesel oil is considered as a heavy cut and LPG as a light gas. A lab scale unit was installed for that purpose. The amount of changes in oil weight before and after atomizing was determines as well as, the properties of the diesel oil like flash point, cetane number, and diesel index. The effect of a wide range of atomizing time (10, 20, 30, 40, 50, 60, and 90) minutes at different temperatures (0, 10, 20, 30, 40, and 50) °C was considered. The data is discussed and graphically analyzed. The optimum operating conditions is achieved by, 9 liters/minute gas Atomizing flowrate of LPG for one liter of diesel oil, atomizing Temperature is 30 ᵒC, atomizing Time is 30 minutes’ minimum till 60 minutes’ maximum. The produced Diesel Flash Point is 55 ᵒC, and the amount of gas absorption is 24 gm per 850 gm of diesel oil which represent 2.8 % of diesel weight and 5% of LPG gas flowrate.

The present work studies the effect of adding woven E-glass fibers [0°/90°], 16 layers with 50% weight fraction to pure epoxy (matrix) on fatigue behavior under constant and variable loadings. The CNC water jet cutting machine was used to cut the composite samples with five fiber direction angles, such as (0°, 5°, 15°, 30°, and 45°). The tensile test was used to determine the composite material’s mechanical properties. The results showed that the composite material with 5° of fiber direction had the highest ultimate tensile stress, i.e., 353 MPa, and the highest Young's Modulus, i.e., 11940 MPa, compared to other samples with angles of (0°, 15°, 30°, 45°) of fiber direction. The sample with 5° angle was adopted in constant and variable fatigue loading tests. The fatigue test results under constant loading showed a 24.8 times fatigue strength improvement for composite material at 107 cycles compared to pure epoxy. The fatigue test under variable loading was conducted with two types of sequence loading program tests at a constant number of cycles at each stress level: high-low sequence loading with stress of 170-130 MPa with 10,000 and 20,000 cycles for each stress level and low-high sequence loading with stress 130-170 MPa with 10,000 and 20,000 cycle for each stress level loading and so on to failure. The results showed that the fatigue life under high-low sequence loading for both 10,000 and 20,000 cycles was less than that of the low-high sequence loading. Also, the results showed that Miner's rules were safe to calculate the damage of composite material used in this work where the damage was above one (D > 1).

A coupled artificial neural network model with a genetic algorithm optimization model is developed for a practical case of a single cutoff. The proposed cutoff is of a soil-embedded vertical part with an inclined extension. The model successfully found the optimum dimensions of the vertical and inclined parts, the optimum angle of inclination, and the optimum length of protection downstream of the cutoff for a factor of safety of 3 against piping. Two thousand one hundred cases are modeled first using Geo-studio software to find the required length of downstream protection against piping for different lengths of the vertical, inclined lengths of the cutoff, its angle of inclination, soil layer depth, and degree of anisotropy. Then the created data set was used to develop an Artificial Neural Network (ANN) model for finding the length of protection required. The ANN model showed high performance with a determination coefficient of (0.922). The genetic algorithm model needs a minimum number of randomly generated populations of 100000 and three crossover iterations to produce a stable optimum solution. Running the model for different practical cases showed that the optimum angle variation was low and fluctuated around 30o. This low angle variation was due to its lower effect on the downstream soil protection length compared to the other decision variables. At the same time, the other dimensions varied with input variables, such as the depth of the soil layer, the seepage driving head, and the degree of isotropy. For a degree of anisotropy (ratio of vertical to horizontal hydraulic gradient) less than 0.5, the results showed no need for protection against piping; hence it is recommended to use minimum dimensions for such a case. The coupled model can easily obtain the optimum dimensions for any given input. Importance analysis showed that the optimum length of the downstream protection was highly affected by the vertical and inclined length of the cutoff, while it was less affected by the angle of inclination. Correlation analysis supported the importance analysis.

Embankment dams are widely constructed due to their suitability with different types of foundation, and it is constructed from the available material at the site. A zoned earth dam consists of a clay core at the center to control seepage supported by a shell. This paper investigated the impacts of side slopes, top width, and shape on upstream and downstream slope stability during different cases. Slide 6.0 software was used to evaluate the factor of safety of side slopes of an earth dam, and its result was validated. Different side slopes range from 0H:1V to 2 H:1V, and crest widths from 3m to 10 m were examined. In addition, for the slanting core case, several cases with varying angles of inclination were provided. The results indicated that by increasing the side slopes of the core, the factor of safety was reduced, especially in the steady state and rapid drawdown conditions. Increasing the top width also reduced the safety factor in the steady state condition. This reduction was because the core material had lower shear strength than the shell material. In addition, in a steady state and rapid drawdown conditions, the cohesion of core material sharply reduced. Compared with the vertical case, increasing the slanting core slopes influenced the slope stability insignificantly during the steady state. The slanting core had benefits in the steady state when the reservoir was full since, in this case, increasing core side slopes affected the slope stability insignificantly. The maximum core side slope in the earth dam and maximum top width, which insignificantly affected the dam’s slope stability, were 0.8:1 and 5 m, respectively.

The naphtha catalytic reforming process is evaluated by designing new composite nano-catalysts. Three catalysts were prepared for this process. The first catalyst was molybdenum carbide composite with platinum over HY zeolite (Mo2C.Pt/HY zeolite), the second catalyst was molybdenum carbide composite with platinum over modified zeolite by cerium nitrate (Mo2C.Pt/CeY zeolite), and the last catalyst was bimetallic titanium and platinum with a titanium content of 1% and platinum content of 0.11% over HY zeolite (Pt.Ti/HY zeolite). All catalysts were tested with several tests, mainly X-Ray Diffraction (XRD), BET surface area, and pore volume. All these substances were applied as catalysts for the reforming process of Iraqi heavy naphtha at the following operating conditions: reaction temperature (480, 500, and 520 ), reaction pressure (10, 12.5, and 15 bar), liquid hourly space velocity (LHSV) at 2 hr-1, and constant hydrogen to hydrocarbon ratio (H2/ HC) of 4. All the reforming reactions occurred in a packed bed pilot plant reactor to investigate its stability and activity during the reforming process. All the developed catalyst samples showed sensational stability even at operating under difficult circumstances. The best catalyst was Pt.Ti/HY zeolite based on the results obtained with respect to the octane number (86.2) at 520 and 15 bar. Also, a mathematical model to describe the reforming process with high accuracy was built and simulated using gPROMS software. The results were very satisfying since the most significant error with the wt% of reformate was 4.9% (the experimental aromatics content was 23.94 wt.%, while the predicted result was 21.67 wt.%), while Research Octane Number (RON) error was 4.7% (the experimental RON was 81, whereas the predicted value of RON was 85) among all the results meaning that the simulating was valid to describe the process.

The common use of an artificial neural network model has been in water resources management and planning. The length, width, and discharge of a basin were measured in this study utilizing field data from 160 Dashti Hawler existing projects. Multilayer Perceptron (MLP) and Radial Basic Function (RBF) networks were employed in the basin irrigation assessment. Input factors included the soil type, the conveyance system effectiveness, and the root zone depth. 130 projects were used for calibration, while the remaining 30 were used for validation. When developing the basin irrigation system, the models’ aforementioned indicators’ performance was evaluated using the coefficient of determination (R2), mean absolute error (MAE), relative error (RE), and Nash Sutcliff efficiency (NSE). For the basin's length, width, and discharge, the (R2) values for the MLP model were determined to be 0.97, 0.97, and 0.96, respectively, whereas the corresponding values for the RBF model were 0.88, 0.89, and 0.89. Compared to the RBF model, the values of (MAE) for basin length, width, and discharge for the MLP model were determined to be 8.99, 8.52, and 42.58, respectively. However, the (NSE) values for the models mentioned above were 0.95, 0.96, and 0.94, as well as 0.65, 0.66, and 0.66 for the basin’s length, width, and discharge, respectively. When it comes to building the irrigation system for the basin, the MLP is more precise than RBF depending on the values of (R2), (MAE), and (NSE). Finally, the ANN approach uses additional design options quickly examine which model is computationally efficient.

The Momentum and Aron & White evaluating methods have been adopted to estimate the Nash Instantaneous Hydrograph parameters (IUH), while the two methods of excess rainfall (Ф-index and Natural Resources Conservation Service (NRCS) were applied in a model using a developed computer program in MATLAB to predict the direct runoff hydrograph for Goizha-Dabashan watershed located in the northeast of Iraq. In the verification stage, both Nash IUH optimal parameters of the storms and the average optimal values of the same parameters estimated in the calibration stage were applied and compared. The statistical tests showed a preference for the NRCS method with the momentum method in estimating direct runoff hydrograph (the average Nash-Sutcliffe Efficiency (NSE) was equal to 0.815 and 0.77 using optimal parameters verification storms and the average calibrated IUH parameters values, respectively). Also, satisfactory results (NSE was equal to 0.77 and 0.76 using storm parameters and the average calibrated IUH parameters values, respectively) were obtained by applying Aron & White with the NRCS methods, which indicated the ability of both methods for estimating direct runoff hydrograph.

The limited availability of the recorded rainfall-runoff data for many watersheds restricts the development and management of different activities of water resources. To overcome this limitation, the Natural Resources Conservation Service (NRCS) for estimating storm excess rainfall and momentum and optimization methods were combined in a mathematical model to estimate the optimal parameters of Nash Instantaneous unit hydrograph (IUH) and resulting direct runoff hydrograph (DRH), using a developed computer program in MATLAB. The available recorded data of 14 storms (out of 18) of four watersheds in northern Iraq have been applied in the calibration stage. An empirical relationship was developed between the average of each IUH optimal parameter (obtained by optimization as an optimal method according to the applied tests) and the effective watershed topographical characteristics. The developed empirical relations were used in the verification stage to estimate the IUH parameters and DRH for the verification storms and compare with that resulted from Haan’s empirical relations and optimization method. The statistical tests showed that the developed empirical relations efficiency was better than that of Haan’s method and close to that of the recorded storm by optimization method, where the average value of the Nash-Sutcliffe Efficiency for the four watersheds resulted from applying the optimization method, Haan’s method and the developed empirical relations were 0.925, 0.587, 0.883 respectively. The results indicated the developed model’s ability to estimate the IUH and direct runoff hydrograph for ungauged watersheds in northern Iraq.

Many oil and gas projects have been subjected to significant cost overruns and schedule delays, which is a major concern for the decision-makers in the oil industry. This paper aims to develop three mathematical models to estimate earned value indicators, the Schedule Performance Index (SPI), Cost Performance Index (CPI), and To-Complete Cost Performance Indicator (TCPI), to reduce the cost and time estimation error in Iraqi oil projects. The research methodology adopted artificial intelligence techniques using Multiple Linear Regression technology (MLR) to predict Earned Value (EV) Indexes to get standard local equations to measure the performance of Iraqi oil projects. The data is based on (83) monthly reports from 26 June 2015 to 25 August 2022 collected from the Karbala Refinery Project, selected as a case study. It is one of the Oil Projects Company (SCOP)- the Iraqi Ministry of Oil’s massive and modern projects, and it combines several projects into one project. The results showed numerous significant points, such as the average accuracy (AA%) for the CPI, SPI, and TCPI was 95.194%, 92.195%, and 83.706%, respectively, while the correlation coefficients (R) were 92.4%, 98.4%, and 93.7%. It was shown that there were relatively few differences between the theoretical and actual results. Therefore, the MLR technique was utilized in this paper to derive the prediction models for its more correct earned value predictions.

This article covers the latest fault-tolerant control system (FTCS) developments and applications. FTCSs aim to maintain stability, minimize performance degradation, and compensate for system component faults. These systems benefit from and mission-critical applications where service continuity is crucial. This article describes several sensor and actuator errors. Fault Tolerant Control (FTC) includes active, passive, and hybrid approaches and the latest design techniques. Finally, FTCS stability and reliability analysis and research gaps were reviewed. This study provides current and future FTCS researchers with the latest trends and applications. This study's contribution. System component failures and instability are two major causes of control performance decline. Fault-tolerant control, or FTC, was developed in recent decades to improve control system resiliency. Active and passive FTC techniques exist. This paper examines control system faults, failure causes, and the latest resilience solutions. Fault detection and isolation (FDI) and active fault tolerance control (FTC) advances were examined. Encouraging FTC and FDI research, a comprehensive comparison of several aspects is performed to understand the pros and cons of various FTC techniques.

Seepage is a dangerous phenomenon under hydraulic structures and the main cause of failure and damage to dams when neglected and not processed. This study evaluates the numerical effects of the sheet piles' quantity, depth, and spacing beneath a concrete dam with isotropic and homogenous foundations on the seepage rate, pressure head, and exit gradient. The solutions were obtained using SEEP/W code in GeoStudio software 2018 for three configurations using single, double, and triple sheet piles. In addition, SLIDE software 6.02 was examined using single and double sheet piles. Dimensional analysis was applied to draw the dimensionless variables that affect the seepage rate and exit gradient, and all tests were repeated for three different sheet pile depths and distances from the heel of the dam. The findings showed that the seepage rate in all studied configurations reduced when sheet pile depth increased. The position of the sheet pile from the dam's toe significantly decreased the seepage rate in cases using single and double sheet piles, while in cases using three-sheet piles, the position of the middle sheet pile insignificant decreased seepage. It was recognized that when using a single sheet pile, the drop in pressure head increased with depths when the sheet pile was located at the heel and middle of the dam. In addition, in the case of a single sheet pile at the toe or using two and three-sheet piles, the pressure drop decreased as the depths increased. Also, the results showed that the middle sheet pile location in the case of three sheet piles slightly affected pressure reduction. Furthermore, the results showed that using two and three-sheet piles was more effective than using a single one in reducing the exit gradient, while the position of the middle one in the case of using three-sheet piles was insignificant. A nonlinear empirical equation was developed using SPSS 22 program, and the comparison of the seepage rate measured by SEEP/W and SLIDE software versus its quantity calculated from empirical equations showed a good agreement as the determinations (R2) coefficients were equal to 0.9779 and 0.9928, respectively.

This paper aims to study the dynamic behaviors of particular sandwich panels manufactured using three specifications of aluminum honeycomb core with fiberglass or aluminum face-sheet materials. Three groups of panels were designed and manufactured, each including three different sorts of samples, all fabricated with the same thickness. A cantilever fatigue test was conducted on specimens, and the results were collected and presented in curves to detect the factors that affect the panel's endurance. The finding showed that the specimens with aluminum skin had more probability of face-sheet/core delamination. Samples of fiberglass covers showed face-sheets cracks or cores cracks more than delamination failure, while samples of epoxy-filled cores experienced the specimen’s global crack. Generally, specimens with aluminum covers and epoxy-filled cores resisted fatigue load more than other specimens. The larger honeycomb cell-size specimens showed more probability to face-sheet/core delamination failures than samples with smaller cell-size cores.

Sulfur compound content in fuels is one of the most undesirable pollutions regarding standard environmental regulations that demand to reduce sulfur concentration limit to 5-10% in fuels. Hence, kerosene’s oxidative desulfurization (ODS) as a model fuel (sulfur content 1158ppm) with air as an oxidant is studied. The goal of the study is to use two different synthesized nanosilica-supported catalysts, CuO/SiO2 (CAT-1) and CuO/TiO2-SiO2 (CAT-2), for the ODS of kerosene. Thirty-two experimental runs were designed via Central Composite Design (CCD) to select the experiments that will be utilized most efficiently. The analysis of variance (ANOVA) was used for statistical analysis to determine the models’ significance. The Response surface methodology (RSM) was used to determine the optimum conditions and parameters significantly affecting the response. Temperature and time are two variables studied due to their impact on oxidative desulfurization. The actual results of sulfur conversion in kerosene from lab experiments were 87% with a sulfur content of 153.3ppm and 99.22% with a sulfur content of 8.9ppm by CAT-1 and CAT-2, respectively, at conditions of 140°C and 100min. The predicted results from experimental design were 86.66% and 99.8% by CAT-1 and CAT-2 at conditions of 140°C and 100min, showing errors less than 3.1% and 1.2% for CAT-1 and CAT-2, respectively, from ANOVA. The optimal parameters of ODS were determined through the sulfur conversion maximization by numerical optimization via ANOVA. The results showed that the maximum conversion by CAT-1 was 99.5% at 140 min and 180°C, and by CAT-2 was 99.7% at 100.1 min and 140.1°C. Also, the rate data were fitted with an empirical kinetic model. The results showed that CAT-1 and CAT-2 activation energies were Ea= 28.2 kJ/mol and Ea= 38.7 kJ/mol, respectively.

Robotic systems play an important role in the development and modernization processes of production, facilitation of labor, and human life. The robotic manipulators are outstanding among such systems. Such robots can be used for various spheres of their application. In this case, there is the manipulator’s effective control problem in the working area, of which there may be various obstacles. Therefore, a procedure is required to find the optimal path for moving the robotic arm. To develop such a procedure, the literature was reviewed, and the structural diagram of the control system of such a robot and its components was summarized. It proposed a mathematical formalization of the search for the optimal path to move the robot arm, an algorithm based on a modified method of navigation graphs, to realize the more natural movement of the robot arm. Experimental studies were conducted with different numbers of objects on the path of robot arm movement, which were combined into groups. The temporal results of this process are presented in a diagram.