Journal of King Saud University, Engineering Sciences最新文献

Improving the quality of syngas from fine coal waste using the sorption-enhanced gasification process is a novel technology in the production of H₂. The effect of CaO on CO₂ absorption and H₂ increase in the steam fine coal gasification process was determined in a fixed bed gasifier. The steam gasification process took place at 650 °C using bentonite and CaO as catalysts and absorbents. Steam increased the H₂ concentration in the syngas to 58 vol%. In-situ CO₂ absorption is more effective with the addition of CaO. The maximum percentage of CO₂ was absorbed when the Ca/C ratio 2 was 78.33 %. The H₂ content in the syngas after the CO₂ was absorbed increased rapidly to 75.80 vol% at a Ca-to-carbon-mole ratio (Ca/C) of 1.5 and a steam-to-feedstock ratio (S/F) of 1.5. CaO did not produce significant results for low heating value (LHV) or cold gas efficiency (CGE), with results of 12 MJ/Nm³ and 44.53 %. The dominant water gas shift reaction due to the influence of steam and CaO increased H₂/CO up to 9.11, which made the syngas from this work suitable for Fischer–Tropsch synthesis.

Among the practical applications of Quantum Physics, photoluminescence has stood out in different contexts in Engineering and Architecture. Due to the photoelectric effect, certain substances emit photons after being exposed to solar energy. In research in Mexico and Europe, these substances were applied to obtain a photoluminescent effect on bicycle paths. The objective of the research is to investigate the behavior of polymeric residues with the luminescent effect of rare-earth materials in the production of concrete artifacts to illuminate pedestrian and cyclist paths. The concrete blocks were produced with the addition of polymeric recycling waste and luminescent materials, exposed to solar radiation, and tested for mechanical strength. The results of the experiments showed that the polymer residue in concrete significantly increases photon emission, especially when it is processed by extrusion. Although the mixture of photoluminescent materials and polymers reduces the strength of concrete, it still met research objectives for a product meant to illuminate pedestrian and cyclist paths.

The Pigeon-Inspired optimization (PIO) algorithm is a novel intelligent optimization algorithm inspired by birds’ behavior as their travel. This; behavior modeled to be used for solving many optimization problems in different fields. However; it always suffers from unstable behavior when used with nonlinear; time-varying systems. In; this paper, this algorithm is adapted to calculate the optimum controller gains for roll and pitch channels in a guided tactical missile. The; vehicle model is presented in a nonlinear; form and then shown in a linearized form for the sake of an autopilot design. The PIO; algorithm is supported and accompanied by an adaptive algorithm to determine the initial states and constraints for the PIO algorithm to enhance the behavior of the optimization algorithm to speed up the convergence rate to reach an optimum and feasible solution. Also; an estimation function is incorporated to estimate model parameters variation such as dynamic pressure, stability derivatives, and mass properties. Meanwhile; a comparative analysis is carried out with original PIO and particle swarm optimization algorithms, utilizing a non-linear; model with the presence of noise source and disturbance to ensure the ability of the algorithm to make the autopilot robust and stable against several sources of uncertainties.

The yttrium aluminium garnet (YAG) and sapphire materials are commonly used in laser and optical devices. Producing an ultra-precise surface quality is necessary for the application in optical devices. However, YAG and sapphire materials belong to difficult-to-machine materials with high brittleness and hardness. Therefore, ensuring the main criterion of producing a quality surface in the nanometre form with the ability to remove the material when finishing this material is challenging. Eliminating machining residues using chemical–mechanical slurry (CMS) is essential in creating ultra-precise components in optical devices. Based on this feature, this work investigates the efficiency of the CMS polishing process by comparing the surface reaction modes with the ionic and solid reaction modes when polishing YAG and sapphire materials. The study procedures aim to clarify the polishing performance corresponding to these two reaction types. Experimental analyses show the balance between CMS polishing technology’s mechanical and chemical effects with the ionic reaction model that can be generated. Results also show that the ionic surface reaction modes give more uniform material removal than the solid reaction on YAG and sapphire crystal surfaces. Therefore, when polished by CMS technology with ionic surface reaction modes, the surface quality is better than solid reaction. In the CMS polishing with ionic responses, adding more Na₂SiO₃–5H₂O content to the CMS is necessary if the chemical reaction is weak. This process will facilitate the –Si–OH components to be more distributed on the workpiece’s surface, thereby improving reaction speed and correcting the balance between mechanical and chemical in polishing by CMS. This balance action results in an ultra-smooth YAG crystal surface without scratches, with a roughness obtained in the nanometre form (Ra = 1.031 nm) after polishing by CMS-2.

Evaporative losses from the water surface are substantial. Continuous floating covers strikingly suppress evaporation, but adversely affect the water environment. However, modular floating “elements” covers might overcome this issue, but with less evaporation suppression efficiency. We hypothesized that modifying the continuous floating covers by decreasing the coverage fraction (CF) could merge the advantages of both types. Two experiments were conducted to evaluate and compare the influence of modular and continuous floating covers on evaporation losses with emphasizing their impacts on the water environment by determining microalga growth as a bio-indicator. The effect of three modular floating covers, i.e., partially water-filled plastic potable bottles (W-PB), air-filled plastic potable bottles (A-PB), and styrofoam (STF)-disks on the evaporation rate was evaluated. In the second experiment, we investigated the influence of white spheres on evaporation rate in comparison to three continuous floating covers, i.e., styrofoam sheet (STF-sheet), white plastic sheet (WPS), and black plastic sheet (BPS), using three CF, i.e., 0.9, 0.95 and 1.0. The results revealed that modular floating covers decreased evaporation rate for the two months by 53.3, 44.6, 43.0% for STF-disks, W-PB, and A-PB, respectively. In the second experiment, the lowest evaporation rate was obtained using continuous floating covers at CF=1, in which all covers were acting equally, signifying the importance of CF over cover color. However, at CF=0.9, white spheres showed similar evaporation suppression efficiency to white continues floating covers, i.e., STF-sheet and WPS, but higher than the BPS, signifying the role of cover color over cover type when CF<1. Microalgae growth was positively affected by STF-disks and white spheres, and negatively by plastic potable bottles treatments. All continues floating covers at CF=1, inhibited microalgae growth, while at CF<1 continues floating covers boosted microalgae growth, except the BPS. In conclusion, the highest evaporation suppression (~95%) was obtained using continuous floating covers at CF=1, but with potential adverse impacts on the water environment. Modifying the continuous floating covers by decreasing the CF, increased water-saving, and enriched water ecology, relative to modular floating covers.

Geometric modeling techniques presented in this study target the important problem of improving the quality of milling processes through simulation-assisted research and development. Geometric modeling capabilities include generating the tool swept volumes for each tool motion, subtracting these from a dynamically changing in-process workpiece model, and calculating the instantaneous cutter engagements. In this study, the workpiece has been represented with a series of evenly distributed vectors oriented in three directions of the Cartesian coordinate system. Thus, sampling in multiple directions, called the triple-ray rap-based method, overcomes the problems associated with z-Map-based techniques, in which sampling only along one direction misses surface portions such as sharp edges and vertical walls. In addition, since the tool-swept volumes are regarded as envelope surfaces in the vector model-based techniques, the intersection calculations have been reduced to line/surface intersections. In the tool engagement extractions, the tool removal volumes represented by the vectors have been utilized instead of the in-process workpiece to reduce memory usage and the program runtime. Later, these removal volumes were voxelized at the predetermined resolutions for performing the arc and voxel intersections. In this research, the milling tools have been modeled as the surface of revolutions. Thereby, the method has been broadened to use more than just the APT type cutters, and it can be generalized for other types of cutting tools.

Seat belts and child restraint systems (CRS) are important in-car safety components capable of preventing serious injuries and death in the event of a car crash. Low rates of seat belt and CRS use persist globally, particularly in the Kingdom of Saudi Arabia (KSA). In an effort to better understand and subsequently improve seat belt and CRS use rates, this study analyzed the factors influencing seat belt and CRS use behavior in the Eastern Province (EP) of KSA, including the connection between seat belt and CRS use and road traffic crash experience.

This cross-sectional study was based on a survey of 3,421 male and female participants regarding their seat belt and CRS use behavior. Respondents were classified into four CRS use categories: cautious, helplessly negligent, ignorantly negligent, and deliberately negligent. Chi-squared tests were used to determine significant associations among seat belt use, seat belt belief, prior crash experience, CRS use, and demographic variables. Multinomial nominal logistic regression was used to estimate the odds ratios for classification in one of the three negligent vs. cautious CRS use categories as a function of demographic variables, prior road traffic crash experience, and belief in and use of seat belts.

Results of this study indicated a modest improvement in the rate of seat belt use in KSA’s EP, however, a significant proportion of respondents reported only sometimes or never using their seat belt. A significant proportion of respondents were also classified in one of the three negligent CRS use categories. Respondents who reported using a seat belt sometimes or never were 2.67, 2.60, and 3.48 times more likely to be categorized as deliberately negligent, ignorantly negligent, or helplessly negligent in their CRS use, respectively, than respondents who reported always using their seat belts. Respondents who reported being previously involved in a car crash or a near crash were also more likely to be classified in one of the three negligent CRS use categories than respondents who reported no prior road traffic crash experience. Previous involvement in a car crash was also found to be associated with lower seat belt and CRS use rates.

These findings suggest a need for increased seat belt law enforcement by the KSA’s Traffic Police Department, as well as additional seat belt and CRS use awareness campaigns targeting individuals with prior road traffic crash experience by the KSA’s Ministry of Communications through the Road Transport Department. This study can serve as a reference for future studies that aim to understand the factors and implications related to seat belt use and belief, CRS use, and road traffic crash experience.

Understanding the phase behavior and volumetric changes of reservoir fluids throughout the extent of reservoir lifetime are crucially required for effective-commercial oil recoveries. Ideally, reservoir fluid properties are experimentally measured by laboratory experiments known as PVT tests nonetheless, these tests are prohibitive, time-consuming, and required to restrict sampling and transporting procedures. For these discernible reasons, several modeling approaches have been developed. By reviewing the literature, one crucial obstacle that encounters field applicability of most extant models is the selection of input variables. Moreover, a great percentage of extant models employ the results of lengthy experimental tests such as differential gas solubility or even the sample’s chemical composition. Replicability of models’ results using different datasets is also one of the main challenges when employing AI models. Frequently, inadequate descriptions for AI models have been provided in many studies which limits their utility. The inadequate description includes the analysis of ANN model weights and biases besides, the final mathematical model. In this study, a rigorous ANN model with its mathematical model has been implemented to predict oil formation volume factors based on 600 compiled datasets from Egyptian oilfields.

A detailed comparison between widely used empirical correlations and the proposed new ANN model is provided in this study. Statistical and graphical analysis depicted the outstanding performance of the new model with R² = 0.974, ARE = −0.0017%, and AARE = 2.13%. The ANN model provides remarkable sustainable performance compared to local Egyptian empirical correlations and all the other global models.

Considering the superior control characteristics and increased tuning flexibility of the Fractional-Order Proportional Integral Derivative (FOPID) controller than the conventional PID regulator, this article attempts to explore its application in the optimal design of the Automatic Voltage Regulator (AVR). Since FOPID has two additional tuning parameters (µ and ʎ) than its mentioned conventional counterpart, its tuning process is comparatively difficult. To overcome the stated issue, a self-regulated off-line optimal tuning method based on the Gradient-Based Optimization (GBO) algorithm is adopted in the current study. The optimal FOPID gains are obtained by minimizing the selected Fitness Function (FF) that is chosen as Integral Time Absolute Error (ITAE) in the current study. The simulations are performed using MATLAB/SIMULINK 2018a to test and compare the performance of the proposed GBO-based optimal AVR design based on the dynamic response, stability, and robustness evaluation metrics with some of the recently published metaheuristic optimization algorithm based optimal AVR designs in the literature. The results show that the proposed AVR design provides the most optimal dynamic response and enhanced stability among the considered AVR designs, thus proves its efficacy and essence.

Due to the increase in human population, there is an ever-increasing demand for energy in different sectors which leads to environmental problems like climate change, rise in temperature, and global catastrophes. Cooling systems have become a very essential element in recent decades for mankind. The present system focuses on the design and fabrication of a counter-flow humidification setup which uses biomass-based charcoal as the packing material. Air velocity and water flow rate have been varied along with the density of charcoal. Output parameters such as a change in pressure (ΔP), Coefficient of performance (COP), evaporation rate (ER), humidification efficiency (HE), specific cooling capacity (SCC), and energy consumption (EC) are evaluated. Performance parameters obtained for charcoal are compared with that of standard Celdek Packing. Through experiments, it is found that humidification efficiencies for Celdek and charcoal packing are 77.45% and 57.40% respectively. The overall coefficient of performance obtained is 1.41 for charcoal and 3.17 for Celdek packing. Among the three densities which were considered, charcoal packing with a density of 400 kg/m³ exhibited higher performance with respect to COP, HE, ER, and SCC. Similarly, a water flow rate of 0.4 lpm gave a maximum performance and 0.7 lpm gave the least. It is concluded that charcoal can be considered one of the highly efficient biomass-based materials contributing to sustainable energy related to cooling applications.