Tikrit Journal of Engineering Sciences

Massive Multiple-Input Multiple-Output (Massive MIMO) is widely regarded as a highly promising technology for the forthcoming generation of wireless systems. The massive MIMO implementation involves the integration of a substantial number of antenna elements into base stations (BSs) to enhance spectral efficiency (SE) and energy efficiency (EE). The energy efficiency (EE) of base stations (BSs) has become an increasingly important issue for telecommunications network operators due to the need to take care of profitability while simultaneously minimizing their detrimental effects on the environment and addressing economic challenges faced by wireless communication operators. In this paper, the EE of massive MIMO networks and the relationship between EE, SE, and other parameters like bandwidth (B), number of antennas (M), circuit power, and number of users’ equipment (K) are discussed and investigated. For a fixed circuit power (PFIX), simulation results showed that the EE could be increased by about 1.12 as the number of antennas was doubled. The findings in this work also indicated an almost linear relationship between maximum EE and optimal SE, with a massive increase in the number of antennas when the power consumed by each antenna (PBS) was included in circuit power. In addition, when considering the power consumed per user’s equipment (PUE) impact, the SE increased with the ratio (M/K), in which SE showed a cubic relationship against M/K. On the other hand, the EE increased with M/K ratio until M/K reached a specific value. The maximum EE (and hence optimum SE) was achieved by massive MIMO, where the number of antennas was three times the number of users. However, EE started degrading after this value, as the number of antennas was considered larger than the users’ and consumed more energy, resulting in EE degradation.

People need artificial limbs for many reasons, such as illness, injury, or a gene problem. However, these limbs must be changed often because the human body changes as it gains or loses weight. This study examines whether plant fibers could be used instead of metal to make sockets for lower limb prosthetics using a vacuum bagging process. The laminates were formed using woven ramie fiber, bamboo fiber, carbon fiber, glass fiber, Kevlar fiber, and ultra-high molecular weight polyethylene UHMWPE fiber. Several mechanical tests, such as impact, maximum shear stress, and flexural tests, were done to investigate the effect of different ways of stacking the fibers on certain mechanical and physical properties. The goal was to find out how changing the orientation and distribution of the fibers affected the composite's properties and how it worked. The outcomes of the tests were evaluated and analyzed to identify the optimal stacking pattern that would yield the desired properties for the composite material. The present investigation demonstrated that the incorporation of diverse reinforcing agents into composite materials exerted a significant influence on their mechanical strength. The composite's properties, such as flexibility, stress tolerance, and toughness upon fracture, improved proportionally with the increasing addition of these materials. The sample with the lamination of (2 perlon + 2 ramie + 2 carbon + 2 ramie + 2 perlon) fiber layers has shown a good impact strength of 81 KJ/m2, a maximum shear stress of 6.07 MPa, and a fracture strength of 174.1 MPa. Novel findings regarding the effect of altering the orientation and distribution of these fibers on the composite's properties could develop more effective prosthetic materials.

The present study implemented energy and exergy analyses on a 750MW combined cycle power plant (CCPP). The research utilized a simulation process using a computer model developed in MATLAB. The model was based on the natural gas combustion concept, energy balances, enthalpy balances, entropy changes, and the CCPPs heat transfer. The model was validated with the case study of the CCPP at Tuanku Ja’afar Power Station, Port Dickson. The results showed that the CCPP’s energy and exergy efficiencies were 56% and 51%, respectively. Furthermore, applying exergy analysis revealed that the combustion chamber had a significant source of exergy destruction rate, i.e., 224.58 MW, which corresponded to 67.48% of the total exergy destruction in the CCPP, followed by the air compressor 7.53%, and the steam turbine 7.07%. Meanwhile, increasing the turbine inlet temperature (TIT) reduced the exergy destruction rate of the combustion chamber of the gas turbine cycle. The optimum performance obtained at TIT was higher than 1262 °C, where the exergy destruction decreased in the CCPP. Moreover, In CCPP, the combustion chamber was the highest exergy destruction rate, i.e., 225MW, among the main components of the power system. It can be grasped that the current adaptive model of natural gas combustion is a powerful tool for predicting the overall performance of the CCPPs based on exergy analysis.

Utilizing thermal storage integrated into a solar air heater SAH is a promising solution to enhance the thermal performance of solar air heaters. The present work experimentally investigated the thermal impact of an absorber-finned heat exchanger-thermal storage unit integrated inside a solar air heater. The experiments were conducted under the conditions of Tikrit-Iraq in December 2021 and January 2022. RT42 and RT50 were used as PCMs in two separate solar air heaters. Each PCM filled the thermal storage of SAH. A finned heat exchanger, in which air was forced through, was immersed in the thermal storage. Two arrangements were tested. In the first arrangement, the two SAHs were separated from each other. In the second arrangement, the two SAHs were connected in series, first the RT42 SAH and then the RT50 SAH. The results showed that the highest recorded temperature was for RT50, i.e., 59 °C, in the separation arrangement. Also, the solar air heater with RT50 in the series arrangement continued to heat the forced air until 5 AM the next day.

The relationship between the rainfall intensity, duration, and frequency (IDF) is widely used in water resources engineering in designing hydraulic structures, such as culverts and sewage systems, and for reducing and controlling floods. In this study, the curves of (IDF) were found for five rain stations registered in different regions in northern Iraq, i.e., Mosul, Tal-Afar, Sinjar, Rabia, and Tal-Abta, and for different periods extending from 1990 to 2019. The Indian Meteorological Department (IMD) empirical equation was utilized to obtain data during short periods, i.e., 10, 20, 30, 60, 120, 180, 360, 720, and 1440 minutes. Also, three probability distributions were used: the Gumble Distribution, the Log Pearson Type III Distribution, and the Log-Normal Distribution, for various return periods (2, 5, 10, 25, 50, and 100) years. Easy fit 5.6 software includes the tests (Kolmogorov-Smirnov, Anderson -Darling (AD), Chi-Squared (χ2)) was used to determine the most suitable distribution for the observed data among the three used distributions. The results demonstrated an insignificant difference between the three applied distributions and the statistics values that fell within the significance level, with priority to the Log Pearson-III distribution.

External strengthening of reinforced-concrete beams is challenging because of the building system complexity or the beam geometry. The major challenge is choosing an appropriate strengthening method to overcome its low torsion strength. Therefore, the main objective of this research is to ascertain how likely it is to suggest or adopt a particular internal in-plane approach to increase the torsional strength. In the present paper, the concept (technique) of adding internal concrete cross-rods (CR) in a transverse direction is adopted. Five concrete beam specimens with 200-, 200-, and 1500-mm dimensions for width, depth, and length, respectively, were poured and tested. One was a reference beam(B-R) without enhancement, while the other four (B-3CR, B-5CR, B-7CR, and B-9CR) were enhanced with three, five, seven, and nine internal cross-rod, respectively. The compressive strength of the concrete was (35MPa) at (28) days (normal strength concrete). This research intends to show how internal cross-rods (CR) and their number affect torsional capability. The experimental findings revealed significant improvements in the ultimate torsion strength capability by about 11.65%, 18.95%, 21.24%, and 27.77%, respectively, compared to the reference beam. The ultimate twisting angle and reinforced beams’ toughness increased by (4.25%-28.36%) and (24.12%-94.48%), respectively, due to the increase in the number of internal cross-rods compared to the reference beam. It was concluded that interior cross-rods would enhance the torsional strength capacity of the reinforced concrete beams. The extent of enhancement depended mainly on the number of internal cross-rods (CR) deployed.

Fluid flow applications to improve water resource management towards sustainable irrigation are one of the main targets of engineers nowadays, especially with global climate change. The performance assessment of the irrigation system is an important area of research to improve water resource management. Through drip irrigation systems, this review evaluated the application uniformity of water and nutrients to sustain agricultural production and protect the environment’s natural resources. To achieve these goals, the adequate use of nutrients and water must be emphasized by utilizing sufficient water and nutrient management approaches, including a drip irrigation system that supplies the inputs immediately to the crop’s root zone. The process operating pressure and the drip line length are the two most crucial aspects that affect the uniformity of the water and nutrient distribution in fields. Inconsistent or inadequate applications of fertilizers and water in the fields contribute to the incorrect supply of useful water and nutrients in the soil profile along the drip line length resulting in a significant decrease in crop yields and poor product quality. The main cause behind the operating pressures in a “micro-irrigation system” is the inadequate distribution of fertilizers and water in the fields. Therefore, the effects of such non-uniform distribution must be carefully quantified and studied to understand the reasons behind soil degradation and groundwater contamination, which occurs due to excess nutrient leaching from the crop’s root zone. Data on the distribution and movement of water and nutrients in the soil is essential for designing efficient fertilization systems. Drip irrigation can reduce water exposure and input costs, making agribusiness more resilient, profitable, and successful. This paper discusses the uniformity of the nutrients and water application for crops grown in various agro-climatic regions. In addition, an effort was made to compare the findings’ quality of various commonly used methods of water and nutrient application under different climatic conditions.

This research examined the effects of micro-straight steel fiber percentage and column form on the punching shear of SFRC slabs. Fibers made of micro steel with a diameter of 0.2 mm and a length of 13mm with an aspect ratio equal to 65 were used. The fiber content varied between 0.5%, 1%, and 1.5% by volume. Four different types of concrete mixes were adopted and tested. Experimental results showed that when the percentage of steel fibers in SFRC increased, its compressive strength, flexural strength, splitting tensile strength, and direct tensile strength improved. This investigation applied a monotonic load to eight cast slabs (two each of conventional concrete of square and circular column sections of the equivalent area while the other six slabs were made with steel fiber concrete. The dimensions of each slab were (920 x 920 x 80 ) mm. Each slab specimen had essential, edge-based support with square and round column sections. It has been demonstrated that slabs with square column sections endured a relatively higher ultimate load than slabs with circular column segments when the steel fiber dosage was 0.5% or 1.0%. Still, at a steel fiber dosage of 1.5%, circular column segment slabs approached the ultimate load of square column segment slabs. The heterogeneous behavior in concrete can be attributed to the random and unequal distribution of steel fibers throughout the material. There were only flexural fractures visible on the tensile face of the slab. New fractures emerged in the center of the slab as the load increased.

Corrosion in steel bars has the biggest effect on the concrete strength as well as its durability. Problems, such as increasing the crack widths, deflections, increasing stresses and decreasing concrete strength, are some subsequences of steel corrosion. Therefore, preventing these undesirable consequences, needs to address by researchers. Some additive materials which can be used in concrete might be the most effective cheap solution. In this research, Styrene Butadiene Rubber (SBR) was utilized in the concrete mixture to reduce water permeability in concrete. In order to test the effect of SBR on steel corrosion in structural members, seven reinforced concrete columns of circular cross section were casted with different contents of SBR, from one percent to six percent of water content. Using accelerated corrosion cells, major tests were done after twenty days. Results show that SBR improved the compressive strength of the concrete up to thirty – one percent with using one percent of SBR. Moreover, the compression strength of the reinforced concrete columns increased about thirty – two percent with using six percent of SBR. Not only the concrete strength improved with adding SBR, but also the steel corrosion resistance increased and steel weight losing decreased.

The dyes make water harmful to humans, animals, and plants and cannot be used until treated. To treat the dyes, non-conventional methods are required, one of which is adsorption with activated carbon. This study aims to produce activated carbon from Cordia myxa fruit (CM) as a low-cost adsorbent to remove methylene blue dye (MB) from aqueous solutions. The characterization of the fabricated-activated carbon was carried out by Brunauer-Emmett-Teller (BET), Fourier-transformed infrared (FTIR), scanning electron microscope (SEM), and X-ray diffraction (XRD) analyses. Different parameters, such as pH (3-9), biochar dose (0.5-5)g/L, initial dye concentration (2-25 mg/L), temperature (25°C), and contact time (0-100 minutes), were examined in batch adsorption experiments. The results showed that the MB dye had a maximum removal efficiency of 68% at a pH of 8, a biochar dosage of 2 g/L, a dye concentration of 30 mg/L, and an 80-minute contact time. The experimental data were analyzed using the Freundlich and Langmuir isotherm models, and their compatibility with the Langmuir isotherm model (R2=0.9989) was excellent. The study of adsorption kinetics used pseudo-first-order, pseudo-second-order, and Elovich models. The results indicated that the pseudo-second-order was the best model to describe adsorption, with R2 and K2 values of 0.99 and 0.0397 g/mg. min, respectively. The negative change in Gibbs free energy (G°) showed spontaneous interaction.

The relationship between rainfall and runoff is complex and directly related to human life, plants, and animals and their whereabouts. Modeling this process requires a suitable hydrologic model to determine accurate results, such as volume and peak discharge of runoff, that can be adopted in the planning and management of water resources. Many factors affect the quantities of surface runoff that can be saved, including climate change and drought. In this study, HEC-HMS was used and calibrated to estimate the runoff volumes and peak discharge for (1986–2018). The initial and constant methods were considered and used to account for the precipitation loss. Snyder's unit hydrograph (UH) was the transform method. Drought characteristics can be analyzed by calculating the severity and duration of drought using the Modified Chinese Z Index (MCZI). The results showed the possibility of applying a rainwater harvesting system to achieve an abundance of water that compensates for the water scarcity in the study area. The seasonal surface runoff ranged from 1361.3-19706.8 (×103 m3) during the study period (1986–2018). Regarding the drought intensity, the region experienced its most severe period in 2007–2008, with a rate of 4.63, followed by 1998–1999 at a rate of 2.48. Both are classified as extreme drought. The study revealed that certain years had a higher intensity of drought and resulted in better water collection than other years when the area was affected by drought.

Clean fuel oil is crucial for a healthy environment and modern life. Therefore, removing sulfur-containing compounds is an effective issue using various techniques for desulfurization. In this study, the oxidation desulfurization (ODS) process was utilized with respect to the prepared new activated carbon (AC) made from apricot shells (AS) loaded by two combined active metals (Nickel-Cobalt-Manganese (NCM) and Nickel-Cobalt-Manganese-Molybdenum (NCMM)). Several characteristics related to the catalysts prepared (mainly SBET, pore volume, FTIR, TGA, SEM, EDX and XRD) have been investigated to analyze the produced nanocatalysts. The new nanocatalysts (NCM/AC and NCMM/AC) were generated by using the impregnation wetness incipient (IWI) method and evaluated for their ability to remove sulfur compounds from whole-cut fuel (from 29-345 °C) based on the air as an oxidant within batch reactor under the following conditions: air flow rate = 2 lit/min, reaction temperature = 90 °C, and reaction time of 60 min for both catalysts. It was found that Nano catalyst NCMM/AC performed better overall in removing sulfur components (57.29 %) than Nano catalyst NCM/AC (44.75 %), and excellent properties have been observed.

Some reinforced concrete slabs may require rehabilitation or strengthening due to load increment caused by a change in the function for which they were built or unintentional errors during design or execution. There are numerous techniques for such problems. The rehabilitation or strengthening of structural members using fiber-reinforced polymer (FRP) is one of the most recent techniques. This technique is widely spread due to its high tensile strength and lightweight; also, the thickness of the strengthened structural member decreases when these materials are used. This paper provides a comprehensive review of several strengthening techniques in terms of their results, advantages, and the extent of their effect on the flexural behavior of voided concrete slabs. Research has shown that this type of strengthening contributes to improving the slabs’ performance, as it contributes to increasing the first crack load and the ultimate load, and it contributes to decreasing the value of the deflection corresponding to the ultimate load and improves the ductility and toughness of these slabs. Also, the flexural strength of these slabs increases with the number of strengthening layers used. CFRP is one of the best types of FRP. It was found that the presence of voids caused a decrease in the flexural strength and an increase in the deflection value; however, the process of strengthening with polymer fibers for this type of slab recovers and compensates for losses from the presence of voids.

Motor imagery (MI) electroencephalography (EEG) technology is acquiring great attention from researchers due to its remarkable real-world applications. EEG signals inherit a high degree of non-stationarity, making their analysis not modest. Hence, choosing an appropriate signal processing approach becomes crucial. This comparative paper aims to identify a suitable signal processing method among famous approaches, namely short-time Fourier transform (STFT), continuous wavelet transform (CWT), and two variations of discrete wavelet transform maximal overlap DWT (MODWT) and MODWT multiresolution analysis (MODWTMRA). Different mother wavelet basis filters experimented with wavelet methods: Morse, Amor, Bump, Symlets, Daubechies, Coiflets, and Fejér-Korovkin. The different methods were tested on the classification of the right-hand and left-hand motor imagery tasks using the brain-computer interface (BCI) competition IV 2b dataset. A shallow convolutional neural network containing a single convolution layer was first trained and then used for classification. The experimental outcomes verified that MI EEG signals can be better analyzed and recognized using the maximal overlap-based signal processing methods. The classification accuracy proved that MODWT and MODWTMRA with the Symlets wavelet outperformed the other methods.

This research is concentrated on the practical design of a portable Induction Heating Furnace (IHF) composed of a Current-Fed Parallel Resonance Inverter (CFPRI) as a power supply of an Induction Coil (IC) and its specimen. The design is intended to reduce the losses in both the switches of the inverter and those due to non-sinusoidal currents in the conductors connecting the power supply components. The IC was connected in parallel to a suitable capacitor to form a tank load in this furnace. Detailed design steps for each implemented part are represented in this research. The implemented power supply tested practically on certain load. The practical results were compared with that obtained from the simulation for this system using the (Plecs) computer package. The practical results agreed with the simulation.

The optimal design of various irrigation systems requires knowledge and a deep understanding of various soil properties. Water infiltration in the soil is among the most prominent of these characteristics. Ten laboratory experiments were conducted to study the effect of the bulk density of stratified soils (two-layered soils), Where sandy loam soil, and clay soil were used. Three bulk density values were adopted for each soil, and experiments were conducted in different sequences. New empirical relationships were derived to calculate the cumulative infiltration depth and the depth of the wetting front in terms of time and the basic infiltration rate of the soil. The results revealed a high agreement between the values measured in the laboratory and those estimated from the proposed empirical equations for infiltration and wetting front depths with a coefficient of determination of 0.96 and 0.98, respectively. The results showed that the infiltration and wetting front depths increased with the cumulative infiltration time and the soil bulk density reduction, regardless of the soil location in the upper or lower layer within the stratified soil. It was also found that the infiltration rate was affected by the density of the upper stratum more than its influence by the change in the density of the lower stratum.

One of the most popular techniques in image steganography is the Least Significant Bit (LSB) operation, which involves inserting secret data into the cover image's pixels' least significant bit. However, the amount of secret data that can be concealed in the cover image depends on the number of bits used for embedding. In this paper, a novel hybrid steganographic system based on Discrete Wavelet Transform (DWT) and Least Significant Bit (LSB) for image steganography is proposed. The proposed scheme aims to optimize data security by utilizing LSB and DWT techniques to embed secret data into an image robustly and efficiently. The present paper focuses on evaluating the algorithm performance by comparing the encrypted image quality using metrics such as PSNR, RMSE, and SSIM. The experimental results showed that the suggested method outperforms the existing LSB-based in terms of security performance. These results indicated that the proposed method consistently outperforms the conventional LSB-based method across all bit depths tested, with an overall improvement of 14.12% in PSNR, 41.87% in RMSE, and 4.02% in SSIM over the traditional LSB. The proposed method enhanced the PSNR values, reduced the RMSE values, and increased the SSIM values for all bit depths tested, indicating higher image fidelity, less distortion, and better preservation of structural similarity of the original image.