Journal of King Saud University, Engineering Sciences最新文献

City traffic conditions contain frequent starts and stops. Thus, Single-Stage Continuously Variable Transmissions are subject to high loads when operating at high gear ratios, leading to excessive friction that cause slipping and heating of friction elements. This study proposes a microprofile with undulation on the surface of the pulley. A mathematical dependence on the technological quality assurance of the surface layer of the V-belt transmission parts formed during turning is proposed, enabling the prediction of height parameters of undulation depending on the change in the spindle speed, feed, and cutting speed. Estimating the error in the field experiment data and calculating values of the proposed methodology showed that the height parameters of the undulation of pulleys have a relative error of 6.3%.

For optimal equipment procurement in Taiwan, first, the specifications and prices of a product are evaluated. Based on these evaluations, procurement decisions are made. Ensuring accurate evaluation criteria for procurement is a multicriteria decision making (MCDM) problem. Printed circuit board (PCB) manufacturers have not grasped the decision-making factors of the new equipment specification, and they continue to use the previous generation specifications as the decision-making criteria for new equipment; this results in inappropriate evaluation criteria. When new equipment with different specifications is launched, purchasers may still use the specifications of older equipment as a basis for their purchase decisions. For example, thermal power generation specifications are often used to evaluate equipment for nuclear power generation. The difference in criteria renders it difficult to make decisions for new equipment. We proposed the use of a scientific method to establish a set of criteria decision-making models for equipment procurement to help PCB factories accurately evaluate contemporary specifications. This research established criteria for new technologies to help decision makers select the most appropriate method. We used the Delphi method and the analytic hierarchy process (AHP) to provide insights into technological and commercial requirements, and a model was further developed for optimal equipment procurement.

Studies have been widely carried out on drying techniques and equipment. The behavior of clays subjected to drying stages requires further research. This study aims to evaluate the behavior of the clay ceramic body during the different stages of the drying cycle and match the characteristics of the raw materials with the final quality of the pieces. In this work, the behavior of three different clays in terms of drying performance was studied. The clays were selected, and their chemical, mineralogical, and particle size characteristics were measured. The mixture design (DoE) developed 10 formulations and was processed through vacuum extrusion. The samples were subjected to forced drying cycles of 180 min by varying the temperature from 30 to 90 °C and air speed from 1.5 to 4.0 m/s. At the end of the cycle, the retraction was a determining factor for the crack probability indicator, where formulations that obtained ∼10% retraction in the dry zone showed losses >25%. On the other hand, it is could be stated that claystone assists the drying process of the ceramic piece, minimizing losses. The drying sensitivity coefficient (k-factor) presented values that reproduce the number of losses during drying, proving to be a valid tool to relate clay properties, drying conditions, and losses in this process. In this case, drying process losses >25% were observed when the k-factor was from 1.6.

The use of natural fibers instead of synthetic fibers has become a hot topic in the reinforced composite manufacturing industry. However, there are considerable differences in the mechanical properties of natural fibers cited in the literature. These differences could be due to the prevalent use of monothetic analysis. In this paper, the use of a simplified Taguchi technique in novel Dioscorea alata stems fiber processing is proposed to allow for simultaneous evaluation of control parameters such as treatment type, harvest condition, gauge length and chemical treatment temperature to determine the optimal conditions for fiber tensile properties. These fibers were extracted from the stem by means of water retting method before chemical treatment. The tensile properties were determined as per ASTM D3822/D3822M-14. Non-destructive examinations were employed to look into the chemical make-up, thermal, crystalline and morphological characteristics of the fibers. The test results showed an optimum tensile strength of 151 MPa and tensile modulus of 5709.5 MPa. Density was 0.4 g/cm³ while cellulose, lignin, moisture, hemicellulose and ash contents were 13.1 %, 10.3 %, 9.7 %, 5.0 % and 8.2 % respectively. The treated fibers were thermally stable till 320 °C. The properties of Dioscorea alata stem fiber (DASF) were found to be promising when compared to existing natural fibers, making it a viable candidate for composite material reinforcement.

In the present paper, the research of the processes of mixture formation is carried out using the method of transportation of light petroleum products — sequential pumping by direct contact. Modeling of the processes of mixture formation is carried out taking into account the influence of parametric factors. This paper is based on a previously published work on non-isothermal pumping of petroleum products in a pipeline. It is also worth noting that in this work, a mathematical model has been finalized to consider the increase in accuracy, namely, accounting in a telescopic pipeline. To perform numerical simulation, a software package was developed that is capable of not only modeling and calculating the parameters of the petroleum product pipeline operation in real time, followed by graphical visualization, but also comparing the obtained data with the real data processed by operators at industrial facilities.

A one-dimensional homogeneous reactor model was developed to simulate the dynamic behavior of a fixed-bed reactor for a catalytic coupling reactor of carbon monoxide and ethyl nitrite to diethyl oxalate. Reactor modeling was performed using a comprehensive numerical model that was simulated using Simulink. The power law kinetic model was applied for simulating the catalytic coupling reaction considering the main and side reactions. The heat of reaction was calculated with respect to the reacted moles of ethyl nitrite for each reaction. When the simulated model reached a steady state, the predicted results were in agreement with the actual data that was collected from an already established pilot plant fixed bed reactor. The startup dynamic behavior of hypothetical industrial-scale production of diethyl oxalate at 78,000 tons per year was simulated. The system reached steady-state within 14–16 min at a space velocity of 1400 h⁻¹.

This paper explains the construction of a novel augmented hunger games search algorithm using a logarithmic spiral opposition-based learning technique. The proposed algorithm (LsOBL-HGS) is used as an efficient tool for both function optimization and controller design. To assess the performance of the algorithm for function optimization, benchmark functions from the CEC2017 test suite were employed and comparisons were made with available and good performing algorithms. In terms of controller design, the proposed LsOBL-HGS algorithm was utilized to design a FOPID controlled magnetic ball suspension system. Comparative assessments were also performed for FOPID controller design, as well using other state-of-the-art methods reported for the magnetic ball suspension system. The results showed that the proposed LsOBL-HGS algorithm has good capability for FOPID controller design employed in a magnetic ball suspension system as it provided an improvement of more than $13\%$ in terms of the transient response-related parameters and more than $34\%$ in terms of bandwidth compared to the best-reported approach used for comparisons.

The present work aims to evaluate the performance of a novel three-phase reactor Belt Conveyor Reactor BCR (with rotating sieve trays patent GB2567340B) as a photobioreactor compared with a traditional Airlift Bubble Column ALR, both influenced by the flow of the gas. Chlorella vulgaris was cultivated in these two photobioreactors using ambient air has a CO₂ concentration of 0.038% with different aeration flowrates 0.145, 0.195, 0.24, and 0.29 vvm (gas volume per minute/liquid volume in the reactor).

The maximum growth rate achieved on the 14th day of culture was 2.120 and 1.420 g/L for BCR, ALR respectively, with initial biomass concentrations of 0.2 g/L and aeration flow of 0.29 vvm. Moreover, the removal efficiency of carbon dioxide sequestration by the two photobioreactors is 40% for BCR and 25% for ALR. The innovative design succeeded in operational quality of agitation with high gas holdup inside the sieve trays to increase the biomass growth up to 50% higher than in the ALR. The maximum CO₂ fixation for ALR was at about 18% at a specific aeration rate of 0.145 vvm in the bubbly regime. Whereas in the BCR can be reached about 38% with wide range operation condition of airflow rate 0.145–0.24 vvm due to well-distributed liquid due to rotating trays, and good gas–liquid mass transfer surface area.

The primary purpose of the pursued research presented in this article was to propose a new technique to create the actual three-dimensional geometry of knots and related fibre deviations and eliminate the inconsistency between modelling the knots as openings or solids. The geometrical and mechanical characteristics of knots and related local disturbed fibre patterns were numerically modelled. The numerical models were experimentally validated by four-point bending tests performed on six timber beams made of Nordic spruce (Picea abies). Tested specimens were sliced up into several strips parallel to the grains in the vicinity of the knot to numerically generate the actual geometrical model of the knots and related fibre deviations for creating the three-dimensional fibre paradigm. The validated numerical models can also be used based on visual inspections. The user needs only to define the position and size of the knot within the timber element required for the 3D finite element model. Moreover, the model allows defining different fibre patterns in the knot vicinity. Results proved that openings can represent knots when found in the tension zone with careful adjustment of the related three-dimensional fibre deviations. Moreover, the results emphasize the need for accurate modelling for the fibre deviations rather than the knot itself.

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.