Journal of King Saud University, Engineering Sciences最新文献

One of the most challenging robotic manipulator designs is finding an appropriate balance between the shaking force and shaking moment because this reduces vibrations. Several approaches have been introduced in the last decades; nevertheless, some assumptions must be established to make such a balance. In this paper, a dynamic balancing approach is proposed. The main novelty is the no dependence on specific trajectories to be executed by the manipulator, which allows finding a design with a similar tradeoff in the balancing under robot configuration changes. Also, the proposal incorporates mass distribution and link shape in a single design procedure. The proposal is stated as a constrained nonlinear optimization problem and applied to a hybrid serial-parallel robotic manipulator. The use of different bio-inspired algorithms and one gradient one in the solution of the balancing problem reveals that differential evolution finds the most suitable design. Besides, comparative simulation results of the obtained design with other design approaches show that the obtained design presents the most suitable tradeoff between the shaking force and the shaking moment when the manipulator executes tasks with different operating velocities.

Electric vehicles (EVs) have assumed prominence due to their enhanced performance, efficiency, and zero carbon emission. This paper proposes an efficient adaptive neuro-fuzzy inference system (ANFIS) based fractional order PID (FOPID) controller for an EV speed tracking control driven by a DC motor. The optimal controller parameters of the FOPID controller are found via an Ant Colony Optimization (ACO) method. The ANFIS controllers are well trained, tested, and validated using the data set sextracted from the fuzzy-based controllers. The performance and accuracy of the ANFIS model are evaluated using statistical parameters such as mean square error (MSE), coefficient of correlation (R), and root mean square error (RMSE). The controller performance, energy consumption, and robustness are tested using the new European drive cycle (NEDC) test. The efficacy of the ANFIS-based controller is demonstrated by comparing its performance with properly tuned fuzzy-based controllers. The proposed controller shows robustness towards external disturbances and offers promising EV speed regulation control. The comparative results illustrate the superior performance of ANFIS-based FOPID controller with high prediction and low error rates. MATLAB- Simulink platform is used for system modeling, controller design, and numerical simulation.

This study offers an investigation into the degree of importance of indicators affecting the sustainable maintenance management of the oil and gas industry. Four dimensions and 12 strategic indicators for sustainable performance are identified, based on literature review and expert opinion on sustainable offshore production. The survey was conducted as a pioneer attempt to evaluate the significance of each indicator, particularly for the Malaysian and Turkmenistan oil and gas industry. In this study, the spherical fuzzy sets modified-Delphi Method was implemented to address the uncertainty and subjectivity in expert judgment. Then, the spherical fuzzy technique in order of preference by similarity to ideal solution integrated approach was proposed to prioritize strategic indicators for assistance in administrating sustainable practices within two developing countries. The study culminated with a set of conceptual indicators intended to promote the implementation of performance benchmarking of sustainable operations in the oil and gas industry offshore.

Rice husk ash (RHA) is a promising pozzolanic alternative material for partial replacement of ordinary Portland cement to increase the durability and strength of concrete and, at the same time, to decrease the corrosion effect caused by the harsh environment conditions. In this study, the impact of adding RHA in different ratios (0%, 7%, and 14%) as a replacement of ordinary Portland cement with different water–cement ratios (0.3, 0.5, and 0.7) and cured in water for different periods (10, 20, and 30 days) both on the durability and strength of the concrete and on its corrosion was investigated. The prepared specimens were tested by flexural, compressive, and tensile strength tests, slump test, and Rapid Chloride Ion Penetration test to determine the suitability of the partial replacement of ordinary Portland cement by RHA in concrete. The most important findings of this work, which is considered novel in this field, are that adding fine (instead of more extensive) RHA particles enhances the flexural, compressive, and tensile strength values and limits the chloride ion penetration with time. An adverse impact was found to increase the water–cement ratio, which is assigned to the effect of water on RHA and as a result on the porosity of the concrete.

The production of hydrogen via photocatalytic water splitting is one of the most promising technologies for obtaining chemical energy from direct solar energy while maintaining the least possible waste and pollutants. In this paper, we obtain the kinetic parameters necessary for the design of a photoreactor for photolysis and photocatalysis of ammonium sulfite solution. For the case of photolysis, we obtain the kinetics for the effect of changing the pH on the produced amount of hydrogen. For the case of photocatalysis, the intrinsic kinetic parameters of photocatalysis of water splitting reaction of ammonium sulfite and water in the presence of cadmium sulfide as a catalyst under solar radiation was inspected by developing MATLAB codes that can predict the kinetics based on the results of experimental work done. The resulted kinetics are compared to experimental work already done. These obtained kinetic parameters provide guidance for the design or scale-up of a solar photoreactor.

An essential requirement during the design of structures is a rational assessment of the ultimate bearing capacity of the footing resting on rock mass (q_u). The q_u is influenced by several parameters, and the simultaneous consideration of all such factors during the assessment of ultimate bearing capacity is a cumbersome process. Considering that the available literature lacks in providing the influence of various parameters of the rock mass on q_u, an attempt has been made in this study to evaluate q_u of a strip footing resting on a rock mass, which was presumed to follow the latest form of Hoek-Brown failure criterion using finite element modeling. The results obtained in this study were validated with the previous findings of the bearing capacity factors (N_σ0) for a footing resting on weightless rock mass. A comprehensive study has been performed to get an insight into the factors affecting the q_u of a footing resting over the rock mass by varying the Geological Strength Index (GSI) ranging from 10 to 100, as well as the disturbance factor (D) at 0 and 1, together with the embedment depth of the footing (D_f). The q_u is determined by the load-settlement response obtained from numerical simulations and the observed potential failure planes from the simulations are analyzed and discussed. The results showed that the q_u was greatly influenced by the GSI of the rock mass and the effect of D reduces with higher values of GSI. The study recommends that the q_u of a poor mass can be increased by placing the footing at a deeper depth (D_f).

This paper studies the fresh and mechanical properties of high-strength concrete (HSC) by incorporating recycled concrete aggregates (RCA) of varying sizes and concentrations. The recycled aggregate concrete (RAC) was prepared by partially replacing RCA with natural coarse aggregate (NCA) at 0%, 15%, 30%, and 45%, with aggregate sizes ranging from 5 to 12 and 12–20-mm. Fresh concrete properties, such as slump, Kelly ball, compacting factor, K-slump, and fresh density, were tested to determine the influence of RCA size and concentration. In addition, the mechanical properties were studied through the execution of compressive, split-tensile, and stress-strain tests. The test results revealed that increasing the RCA concentration declines the fresh and hardened properties of HSC. In the fresh concrete experimentation, the 12–20 mm aggregate size RAC mixes exhibited greater workability than the 5–12 mm aggregate mixes. On the contrary, 5–12 mm aggregate mixes RAC had higher compressive and split-tensile strength and a higher modulus of elasticity than 12–20 mm aggregate mixes concrete. When it comes to sustainability, the study found that the smaller size range of RAC produces inferior embodied CO₂ (eCO₂) and provides a cost-effective and sustainable solution for the construction industry.

The advancement in the tensile strength and ductility of plain concrete can minimize the quantity of materials required per unit strength to build eco-friendly structures. This paper compares the compressive and flexural behavior of different strength classes (C20, C30, and C45) of concrete with the varying volume fractions of hooked steel fiber (HSF) considering the application of concrete road. The performance of each strength class was evaluated and compared based on the compressive and tensile testing results. Using the mechanical properties of concrete mixtures; the design thickness, cost, and global warming potential of concrete pavement were calculated and compared between different mixes under the same traffic loadings. The results showed that the maximum utilization of HSF was observed in the high-strength C45, whereas HSF showed comparatively low efficiency in low-strength C20. At 0.25% volume of HSF, low strength C20 concrete showed higher residual strength and flexural toughness than that of the plain high strength C45 concrete. The analysis of design thickness of pavements revealed that low-strength C20 at 0.25–0.5% HSF can provide cost-effective and eco-friendly pavements compared to a plain high strength C45 for the same design loadings. The results of this study provide useful insights on the selection of strength class and concentration of steel fiber for pavement application.

Due to its environmental, economic, and durability advantages, sustainable concrete has considerably increased the potential of research in recent years. This paper investigates how rubber waste affects the mechanical properties, durability, and microstructure of the concrete matrix. Industrial rubber such as ground latex gloves (LG) and silicone catheters (SC), are substituted for coarse aggregate in concrete mixes. Workability, density, compressive strength, water absorption, ultrasonic pulse velocity, and scanning electron microscope (SEM) tests are applied to examine the performance and properties of the modified concrete. The impact of high temperatures on concrete containing industrial rubber is also examined. To achieve this objective, the samples are tested at normal and high temperatures (room temperature, 200 °C, and 400 °C, respectively) and four substitution levels are used (2.5%, 5%, 7.5%, and 10%) by weight. The results illustrate that the inclusion of different percentages of the LG and SC significantly improves the water absorption of the concrete samples. In addition, the density of concrete containing recycled rubber decreases by 34%. Compressive strength decreased by 86% and 59% at a replacement level of 10% for LG and SC, respectively. High-temperature level has shown a significant effect on the properties of rubberized concrete. This study establishes the possibility of incorporating LG and SC at limited replacement levels in concrete; thereby, proving that these materials are applicable in industrial use.