Journal of Engineering Research最新文献

Background

Chaotic oscillations within the power system give rise to instability. While these oscillations may not have an immediate impact on the synchrony of the machine, they stimulate one of the oscillation modes, ultimately leading to voltage collapse and a loss of synchronism.

Objective

This paper introduces a modified Whale Optimization Algorithm (WOA)-based Battery-STATCOM (Static Synchronous Compensator) as a solution to mitigate chaotic oscillations within a Single Machine Infinite Bus (SMIB) system.

Methodology

An adaptable controller is implemented to manage the gate signal within the Battery-STATCOM. The AC-DC currents of this controller are optimally governed by two distinct WOA-tuned Proportional-Integral (PI) controllers. The battery storage unit serves as a robust voltage source, with the intelligent controller maintaining the DC-link voltage at the desired level.

Test Cases

Additional disturbances, such as gradual variations in reference voltage and electromagnetic torque, are introduced to exacerbate chaotic oscillations. This is done to assess the controller's real-world performance under adverse conditions.

Results and Conclusion

Under zero damping conditions, rotor parameters, including rise time, settling time, peak time, and overshoot, initially remain undefined due to uncontrolled oscillations. However, once the Battery-STATCOM is applied, these parameters are defined and achieve values (in seconds) of 0.90, 6.21, 1.71, and 21.10, respectively. After further optimization through the proposed modified WOA optimizer, the parameters reach values of 0.25, 1.01, 0.89, and 1.78, respectively. These results underscore the effectiveness of the proposed metaheuristic controller in suppressing overall chaotic oscillations within the power system.

During the construction of earth−rock dams in cold regions, the freezing−thawing of impervious soil causes significant changes in its physical and mechanical properties, which affects the quality and operation safety of the project. To enhance the impervious soil anti−freezing capacity, the hollow polycarbonate panel heating method (HPPHM) was innovatively proposed. Based on the mechanism and in−situ tests, the heating mechanism and effect of HPPHM on impervious soil were investigated. The test results indicated that HPPHM can primarily heat the soil through solar radiation, raising the soil temperature. Furthermore, the air layer inside the panel serves as thermal insulation, effectively preventing the soil internal heat from dissipating. The in−situ test results showed that soil freezing was not observed under HPPHM, and the soil surface temperature was approximately 6 °C higher compared to the control site. The heating influence depth of HPPHM on the impervious soil was approximately 175 cm. Additionally, the soil heat under HPPHM experienced a significant increase of 12537.1 kJ. This study provides a scientific method for improving construction efficiency and quality in cold regions.

Cancer therapies are currently limited to surgery, radiation, and chemotherapy. All three methods risk damage to normal tissues or incomplete eradication of the cancer. Nanotechnology offers the means to target chemotherapies directly and selectively to cancerous cells and neoplasms, guide in surgical resection of tumors, and enhance the therapeutic efficacy of radiation-based and other current treatment modalities. All of this can add up to a decreased risk to the patient and an increased probability of survival. In the recent research, the properties of green formulation of silver nanoparticles by Malva sylvestris on human renal cell carcinoma cells were checked. The NPs characterization was run by the techniques of FT-IR, TEM, FE-SEM, and UV-Vis. The MTT assay was used to measure anti-renal cell carcinoma (against RCC-JW (KTCTL-195), RCC-GH, CaKi-2, and HEK293 cell lines) and cytotoxicity (against HUVEC cell line) activity of silver NPs. Interestingly, the nano-drug could resist significantly against those cell lines in a time and concentration-dependent manner, assessed by MTT method. The corresponding IC₅₀ values of the nanoparticles were 118, 135, 66, and 147 µg/ml respectively against the RCC-JW (KTCTL-195), RCC-GH, CaKi-2, and HEK293 renal cell carcinoma cells, respectively. After doing the clinical trial studies, the recent silver nanoparticles may be used for the treatment of renal cell carcinoma in humans.

This paper proposes that the light intensities of adjacent interior spaces should be concurrently evaluated to reduce the risk of glare when evacuees transition between spaces to reach the final exit. The prevention of glare during daytime evacuation has the potential to smoothen the evacuation process from a building. As all legislative, regulatory, and assessment tool recommendations currently used in Malaysia measure illuminance (in lux), this paper similarly evaluates illuminance instead of luminance for ease of initial adoption in the country. Illuminance recommendations in MS1525:2019, LEED, DOSH Guidelines, UBBL, GBI, GreenRE, Melaka Green Seal, and MyCREST were compared to determine the contrast ratio. The illuminance contrast is greatest at the final exit points, such as from parking structures, lobbies, and staircases, which are benchmarked against the Malaysian sky illuminance that can reach 100,000 lux. A contrast ratio as high as 2000:1 may occur if Malaysian offices were designed to only achieve the minimum illuminance requirements. Of the three assessed final exit spaces, naturally-lit fire escape staircases were selected for modelled simulation of illuminance performance using VELUX Daylight Visualiser 2. The findings ascertained that most typical staircase layouts are able to exceed the minimum illuminance requirements at noon, when the sun is potentially the most intense, although the contrast ratio may still reach 1480:1. While the contrast between intermediate spaces are acceptable, those between the final exit transitions and the outdoors are high, suggesting a risk of glare. Further studies are required to determine strategies to facilitate visual adaptation for Malaysians, such as the identification of an ideal acceptable illuminance contrast ratio, temporal adaptation period, or distance-based parameters.

The present study focuses on the influence of the strengthening grinding process (SGP) on the corrosion resistance of CSS-42 L alloy. To this end, the surface and cross-sectional characteristics of samples before and after SGP treatment were examined. In this regard, the surface morphology, roughness, microstructure, and phase content were analyzed. The results demonstrate a dense surface layer and a high surface roughness in SGP-treated samples. Through electrochemical and salt spray tests, it is confirmed that SGP treatment for 3 and 6 min improves the corrosion resistance of samples. It was found that the highest corrosion resistance can be achieved after SGP treatment for 6 min. The enhanced corrosion resistance of the SGP-treated samples originates from the synergistic effects of various factors, including surface roughness, dislocation density, the presence of compressive residual stress, the precipitation of Cr-phases, and the deformation of a dense surface layer.

Public and private sector organizations continually seek to optimize strategies for sustained competitiveness by reallocating resources efficiently among various institutions. This research introduces a non-radial resource reallocation model employing network data envelopment analysis to address this need. The study introduces an approach to redistributing resources in a dynamic network setting over multiple periods. It takes into account indicators of both negative outcomes, aiming to improve the overall effectiveness and efficiency of companies within a holding structure. The research outlines a methodology, including data collection, modeling assumptions, decision variables, and constraints for implementing this reallocation model. By focusing on resource allocation in network systems over periods, this study provides a solid foundation for enhancing resource allocation efficiency in organizations. Additionally, it addresses the complexities associated with resource allocation compared to settings. The proposed dynamic network DEA model considers both temporal aspects in evaluations. Demonstrates its potential for resource allocation in multi-stage processes through applications within the banking industry. One key finding is the importance of recognizing shared constraints among Decision Making Units (DMUs). Considering the impact of restrictions, like government regulations, on decision-making processes and overall efficiency. The created dynamic network DEA model introduces an inventive method to redistribute resources in intricate organizational setups. It offers perspectives for decision-making procedures. Moreover, it sets the stage for further exploration into different indicators and the impact of diverse government interventions on resource allocation effectiveness.

The accurate design of the shell-and-tube heat exchanger (STHE) model is crucially important for industries such as process industries, oil refining, thermic devices, and power plants. However, determining its parameters is a challenging task due to the multimodality and nonlinearity of the cost function. Due to such nature, performing algorithms face the challenges of sluggish convergence speed and the proneness to local optima, making it difficult to reach satisfactory solutions. In line with the above challenges, this paper aims to contribute by developing an improved optimization algorithm that can effectively deal with such optimization issues. The proposed algorithm, named Levy-Opposition- Equilibrium Optimizer (LOEO), combines the Equilibrium Optimizer (EO) and the strategies of opposition learning (OL) and Levy flight learning (LFL) to overcome the dilemma of early convergence and getting trapped in local optima. It does this by employing the OL and LFL strategies after performing the EO phase to explore the search space in opposite directions and exploit the search space by means of the Levy distribution pattern, respectively. The proposed LOEO approach aims to enhance the algorithm's ability (provides enhanced exploration capability, effective search space exploitation, and enhanced convergence speed) and reach higher quality solutions to optimization problems. To assess the performance of the suggested LOEO, three stages of analysis are carried out. In the first stage, the performance of the proposed algorithm is investigated on some benchmark problems, including CEC 2005 and CEC 2020, using statistical verifications, convergence behavior, and the boxplot paradigm. The second stage involves the non-parametric Friedman test to assess the significance of results, where the results indicate that the LOEO outperforms the best existing one (equilibrium whale optimization algorithm (EWOA)) by an average rank of the Friedman test greater than 28% for CEC 2005 benchmark functions while outperforming enhanced EO (EEO) by 24% for CEC 2020. Finally, the LOEO's applicability is realized through determining the optimal design structure of the STHE model. The reported results indicate that the LOEO algorithm offers accurate performance compared to competing algorithms as it saves the cost of the device by 39.81% compared to the best existing results, and thus, it is commended to adopt for new applications.

Mechanical and microstructure properties of weld joint between mild steel plates before and after heat treatment process have been studied. In this study, electric arc welding was used as a welding method as it is the most common welding method. Then heat treatment of the samples were done in the furnace. Firstly, in the heat treatment process, stress annealing was done as stress generated at different places in the welding zone and after that full annealing was done using furnace cooling for cooling purpose. Tensile strength was measured using ASTM A370 standard specimen and Brinell hardness test was done at different surfaces of the welding zone. The microstructures were observed by cutting the specimen in a certain shape, and mirror surfaces were generated to observe in electron microscope. From the results, it was observed that PWHT causes a 4.1 % increase in tensile strength, a 13.84 % gain in yield strength, and a 4.96 % rise in percentage elongation. However, the value of hardness decreased 19.19 % after heat treatment as heat treatment increased the ductility of the specimen. At the place of the Electric Arc Welding joint, a smaller grain size, a lower gap between the grains, and comparatively few voids were identified.

Ensuring the availability of a cost-effective method to predict soil behavior is imperative for newly developed construction sites. This research aims to create a model that can estimate the spatial distribution of soil properties and compaction characteristics using the Inverse Distance Weighting (IDW) and Geographic Weighted Regression (GWR) methods within the study area, specifically in Koya city, situated in Erbil, Iraq. To determine these soil parameters, 27 soil samples were collected from the fields based on stratified random sampling, and then tested and analyzed in the laboratory. The IDW spatial interpolation technique and GWR method were then used to create a spatial distribution map of soil properties and compaction characteristics. In the GWR model, the calculated soil properties and compaction characteristics served as the dependent variable, while the Modified Normalized Difference Water Index (MNDWI) derived from the Landsat8 satellite image was the independent variable. This process resulted in a spatial distribution map showing the soil properties and compaction characteristics. The results indicated a strong correlation between the MNDWI water indexes and various soil parameters, including water content, liquid limit, plastic limit, optimum moisture content, and maximum dry density, with respective coefficient of determination (R²) values of 0.91, 0.97, 0.98, 0.95, and 0.96. Additionally, the assessment of the precision in this correlation indicates that the results maintain a satisfactory level of accuracy, as demonstrated by the Root Mean Square Error (RMSE) values, which are 2.86 for water content, 5.4 for liquid limit, and 3.85 for plastic limit, 2.9 for optimum moisture, and 13.86 for maximum dry density. By integrating satellite-derived MNDWI water indexes with soil parameters, a fast, accurate, and cost-effective method for estimating soil parameters and modeling their spatial distribution in the study area can be developed. Additionally, the findings suggest that the IDW method, implemented using spatial analyst tools, performed exceptionally well for mapping the study area. In conclusion, the results of this research can be utilized by land use planners, municipalities, policymakers, and engineers to develop practical and effective plans.

Osteoporosis means a decrease in bone density, as a result of which bone strength decreases and becomes brittle, which increases the probability of fracture. Osteoporosis usually develops gradually and does not show any symptoms until a fracture occurs. Osteoporosis can occur in any bone of the body, but it is usually seen in the spine, pelvis, wrists, and ribs. Both men and women at any age may be affected by this disease, but according to statistics, the percentage of women suffering from osteoporosis is higher than men, and the probability of this disease increases with age. Recently, the metallic nanoparticles containing plant extracts have been used for the treatment of bone disorders such as osteoporosis. The obtained nanoparticle (Gold nanoparticles green-formulated by Glycine max L seed extract) was characterized by advanced chemical and physical techniques like TEM, FTIR, and SEM. The cytotoxicity effects of gold nanoparticles against normal cell line i.e. HUVEC were assessed. Administration of gold nanoparticles ‎following methyl prednisolone sodium succinate induced osteoporosis in Wistar rats indicated a raise in the bone mineral content markers serum levels and a reduction in bone resorption markers urinary and serum levels. An incline in tibia and femur strength was observed particularly with 5 µg/kg of gold nanoparticles‎. Calcium homeostasis maintenance, collagen formation and free radicals scavenging can plausibly be the gold nanoparticles action mode ‎thereby combating osteoporosis induced by glucocorticoids.