Based on the solid−liquid two-phase flow model, SST k-ω model, and Lagrangian equation model of particle motion, numerical simulations of the sediment−water flow in the injector of a large Pelton turbine were conducted. The distribution rules of pressure, velocity, erosion rate, and erosion location of the injector were obtained by analyzing the sediment−water flow characteristics and sediment erosion distribution characteristics of the injector. The results revealed that the velocity distribution trend of the water inside the cylindrical jet exhibited a nonlinear distribution, and the phenomenon of “velocity deficit” occurred at the end of the needle guide and needle tip, resulting in a decrease in the jet quality of the injector. The sediment particle diameter affected the erosion rate of the needle and erosion location of the needle and nozzle port ring. This study provided guidance for sediment erosion analysis and the prediction of the utility of large Pelton turbines.

This study proposes a new isolated intelligent adjustable buck-boost (IIABB) converter with an intelligent control strategy that is suitable for regenerative energy systems with unsteady output voltages. It also serves as a reliable voltage source for loads such as battery systems, microgrids, etc. In addition, the hill climbing (HC) maximum power point tracking (MPPT) algorithm can be utilized with this innovative IIABB converter to capture the MPP and then enhance system performance. In this converter, five inductors (LA, LB, LC, LD, and LE) and four power MOSFETs (SA, SB, SC, and SD) are used in the proposed novel isolated intelligent adjustable buck-boost (IIABB) converter to adjust the applied voltage across the load side. It also has a constant, stable output voltage. The new IIABB converter is simulated and verified using MATLAB R2021b, and the performances of the proposed IIABB converter and conventional SEPIC converter are compared. The solar photovoltaic module output voltage... [more]

Sulfamethoxazole [SMX] and metronidazole [MNZ] are emergent pollutants commonly found in surface water and wastewater, which can cause public health and environmental issues even at trace levels. An efficient alternative for their removal is the application of adsorption technology. The present work evaluated single and binary adsorption processes using granular activated carbon (CAG F400) for SMX and MNZ in an aqueous solution. The binary adsorption process was studied using a Box−Behnken experimental design (RSD), and the results were statistically tested using an analysis of variance. Density functional theory (DFT) modeling was employed to characterize the interactions between the antibiotics and the CAG F400 surface. For the individual adsorption process, adsorption capacities (qe) of 1.61 mmol g−1 for SMX and 1.10 mmol g−1 for MNZ were obtained. The adsorption isotherm model that best fit experimental data was the Radke−Prausnitz isotherm model. The adsorption mechanism occurs th... [more]

Limestone with a particle size of less than 5 mm was rapidly calcined in a high-temperature resistance furnace at 1623 K to simulate the conditions of rapid calcination of limestone at ultra-high temperature in a converter. In this study, the decomposition mechanism and calcination characteristics of small-sized limestone at steelmaking temperature were investigated. The study shows that the shrinking sphere or cylinder models with phase boundary reaction were found to be the best representation of limestone kinetic data, and the mechanism function equation is G(α) = 1 − (1 − α)n, n = 1/2 or 1/3. Limestone particles with a size of 0.18−1.0 mm can be quickly calcined to obtain a typical active lime microstructure and a high activity of more than 350 mL, which is the preferred limestone particle size range in the steelmaking process in which limestone powder is injected into the converter.

Exploring the relationship between formation pressure and shale pore evolution is helpful for the enrichment and development of marine shale gas accumulation theory. The thermal evolution experiment was carried out on the Xiamaling Formation (Pr3x) lowly matured marine shale, which has a similar sedimentary environment to the Longmaxi Formation (S1l) highly matured marine shale. Comparative experiments of open and semi-closed pyrolysis and multiple pore structure characterization techniques, including CO2 and N2 physisorption, mercury intrusion porosimetry, and field emission scanning electron microscopy, were conducted. The marine shale pore evolutionary model under formation pressure is proposed by characterizing pore evolution, and hydrocarbon expulsion and retention for shales under and without formation fluid pressures. The results show that the existence of formation pressure increases the percentage of quartz and reduces the content of clay minerals. The change in formation pres... [more]

High-potential nanomaterials were derived from rice straw using the integrated biobased processes of enzymatic hydrolysis with green organic acid hydrolysis assisted with ultrasonication pretreatment. The optimization condition of nanocellulose preparation by enzymatic hydrolysis via central composite design (CCD) achieved a maximum nanocellulose content of 32.37 ± 0.47% using a cellulase concentration of 107.06 U/mL and 0.13% (w/w) of rice straw cellulose. The ultrasonication-assisted pretreatment prior to enzymatic hydrolysis improved nanocellulose preparation to 52.28 ± 1.55%. Integration with oxalic acid hydrolysis increased the nanocellulose content to 64.99 ± 0.16%. Granular nanocellulose was obtained and consisted of a 105−825 nm nanosize with a zeta potential value of −34.5 mV, and nanocellulose suspension showed high stability without aggregation. In addition, the remaining rice straw cellulose after oxalic acid was microcrystalline nanocellulose. All prepared nanocellulose re... [more]

Microorganisms (Acidithiobacillus ferrooxidanns) are effective in oxidizing ferrous ions that can be used to oxidize pyrite and produce sulfuric acid. Many coal waste resources contain significant concentrations of rare earth elements (REE) and critical materials (CM) that can be extracted using sulfuric acid. These coal waste resources often contain significant concentrations of pyrite, which if not utilized or removed present a future environmental liability for potential acid mine drainage. Thus, the combination of pyrite and REE/CM in coal waste provides a significant resource opportunity for sulfuric acid generation that can be utilized using biooxidation. In addition, the pyrite concentrate used for acid generation also contains REE/CM content that is released during biooxidation of the pyrite concentrate that augments the REE/CM release from the main ore being leached with the acid generated from the pyrite. Thus, this approach provides a very significant environmental advantage... [more]

KIT-6 silica with well-ordered three−dimensional (3D) mesopores has been synthesized as a support for nickel-based catalysts. Transmission Electron Microscopy (TEM) and low-angle X-ray Diffraction (XRD) analysis are used to ensure that the ordered 3D mesostructure is stable after NiO incorporation. In this study, the catalytic activities of the NiO/KIT-6 samples are investigated. Additionally, the results show that a 10 wt% NiO/KIT-6 catalyst exhibits high catalytic performance in methane combustion, with T10, T50 and T90 being only 386 °C, 456 °C and 507 °C, respectively. Hydrogen Temperature Programmed Reduction (H2-TPR) studies have shown that the interaction between NiO and KIT-6 in the 10 wt% NiO/KIT-6 catalyst is weak. Methane Temperature programmed Surface Reaction (CH4-TPSR) results show that the surface oxygen of the NiO/KIT-6 catalyst allows it to exhibit a high catalytic performance. NiO/KIT-6 catalysts exhibit superior activities to SBA-15, MCF and SiO2 support catalysts be... [more]

Skin lesions affect millions of people worldwide. They can be easily recognized based on their typically abnormal texture and color but are difficult to diagnose due to similar symptoms among certain types of lesions. The motivation for this study is to collate and analyze machine learning (ML) applications in skin lesion research, with the goal of encouraging the development of automated systems for skin disease diagnosis. To assist dermatologists in their clinical diagnosis, several skin image datasets have been developed and published online. Such efforts have motivated researchers and medical staff to develop automatic skin diagnosis systems using image segmentation and classification processes. This paper summarizes the fundamental steps in skin lesion diagnosis based on papers mainly published since 2013. The applications of ML methods (including traditional ML and deep learning (DL)) in skin disease recognition are reviewed based on their contributions, methods, and achieved res... [more]

This work first transformed hazardous aluminum waste into low-cost MgAl−layered double hydroxide@ANA zeolite (LDHs@ANA) composite for dye wastewater adsorption, which was meaningful for waste recovery and pollution control. Based on this strategy, the Al(OH)3 extracted from secondary aluminum dross (a hazardous waste in the aluminum industry) was used as an aluminum source to synthesize LDHs@ANA composite, which had more excellent adsorption capacity to methylene blue than MgAl−LDHs and ANA alone. The composite consisted of spherical ANA particles uniformly covered with LDH nanosheets, which effectively avoided a large amount of aggregation between nanosheets and increased specific surface areas and pore volumes. The kinetic results indicated that the adsorption process conformed to the pseudo-second-order kinetic model, and the adsorption site was the main factor affecting the adsorption process. The equilibrium studies showed the adsorption process was exothermic, and the Langmuir mo... [more]

Renewable energy power prediction plays a crucial role in the development of renewable energy generation, and it also faces a challenging issue because of the uncertainty and complex fluctuation caused by environmental and climatic factors. In recent years, deep learning has been increasingly applied in the time series prediction of new energy, where Deep Belief Networks (DBN) can perform outstandingly for learning of nonlinear features. In this paper, we employed the DBN as the prediction model to forecast wind power and PV power. A novel metaheuristic optimization algorithm, called swarm spider optimization (SSO), was utilized to optimize the parameters of the DBN so as to improve its performance. The SSO is a novel swarm spider behavior based optimization algorithm, and it can be employed for addressing complex optimization and engineering problems. Considering that the prediction performance of the DBN is affected by the number of the nodes in the hidden layer, the SSO is used to o... [more]

In this study, Zn(NO3)2·6H2O was selected as the metal source, and ZIF-7-modified magnetic graphene-based matrix materials (MRGO@ZIF-7) were prepared by in situ growth. ZIF-7 modified magnetic graphene-based molecular imprinting complexes (MRGO@ZIF7-MIP) were successfully synthesized by a surface molecular imprinting technique using bisphenol A (BPA) as the template molecule. The obtained experimental materials were characterized by X-ray diffraction (XRD), Brunner−Emmet−Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS). The proper adsorption and selective recognition ability of the MRGO@ZIF7-MIP were studied by an equilibrium adsorption method. The obtained MRGO@ZIF7-MIP showed significant molecular recognition of bisphenol A (BPA) and good selectivity and reproducibility for BPA in different aqueous environments such as drinking water, river water, and lake... [more]

The low thermal conductivity of gypsum-based composites containing phase change materials (PCMs) has limited their application in construction materials. In this study, the mechanical and thermal properties and microstructures of paraffin (PA)/gypsum composites containing iron powder, copper powder, and expanded graphite were characterized by a universal testing machine, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy. The PA/gypsum composites had optimal mechanical properties when the PA content was 20 wt.%. The compressive and flexural strengths were 9.46 MPa and 3.57 MPa, respectively. When the copper powder content increased, the densities and porosities of the PA/gypsum composites containing the copper powder did not largely change. The average density and porosity of the composites were 1.17 g/cm3 and 46%, respectively. The compressive and flexural strengths of the PA/gypsum composite containing 8 wt.% copper powder were optimal. A phase chan... [more]

In order to explore the evolution of physical and mechanical properties and acoustic emission (AE) characteristics of aluminum foam under fatigue and quasi-static compression from a microscopic point of view, the AE monitoring technology was used to analyze the deformation, hardening, and energy absorption characteristics of open-cell aluminum foam under quasi-static compression at different rates (2, 10 and 50 mm/min) and fatigue loading tests with different peak stress ratios k (k = maximum stress/yield stress) by means of MTS fatigue testing machine and CCD camera. The results indicated that under different compression rates, the AE ring down count had the same trend as the engineering stress−strain response of the specimens, the AE ring down count rate at the plastic deformation stage showed the same performance as the work hardening rate, and the AE energy absorption efficiency corresponded well to the experimental results. The specimen entered the densification stage with the sta... [more]

Fixed-bed pyrolysis of torrefied spruce wood, for a heating temperature of 800 K, results in char yields between about 27−57 wt% (versus 23 wt% for untreated wood), depending on both pre-treatment temperatures (533−583 K) and holding times (8−25 min). In this study char oxidation behavior and kinetics are investigated by means of thermogravimetric analysis. The differential thermogravimetric curves always showed a low-temperature zone of slow rates (oxidative devolatilization), followed by a high-rate zone with a well-defined peak (oxidation). As the torrefaction severity increases, the temperature range of the oxidative devolatilization enlarges. Moreover, the oxidation rates become slower (both burning and burnout temperatures tend to increase). As already found for untreated wood chars, the two stages are well described by a linear and a power-law rate reaction, respectively. Volatiles released from the devolatilizations are approximately around 20 wt%, but torrefaction causes lower... [more]

The residual stresses state that a mechanical part obtained after machining is a crucial factor that impacts its in-service performance. This stress state is influenced by the thermomechanical loads exerted on the parts during the machining process, which are, in turn, determined by the tool parameters, process, and machining conditions. The aim of the present research was to anticipate how the cutting tool’s edge radius, rake angle, and clearance angle would affect the forces, temperature, and residual stresses induced while orthogonally cutting aluminum AA6061-T6. To achieve this, two-dimensional DEFORM™ software was utilized to develop a finite element model. The residual stresses trend results obtained demonstrated that rake angles of 0° and 17.5−20° values with a small edge radius (5 to 10 µm) and clearance angles of 7 and 17.5° values gave higher compressive stresses. The obtained simulated results were in good agreement with the experiments. The cutting forces, the temperature,... [more]

Composites of sawdust and crushed polyethylene were obtained by pressing at 5−10 atm. The resulting pellets with a size of about 10−20 mm were then burned in airflow in a muffle furnace at a temperature of 800 °C. The combustion process was recorded, and obtained video data were analyzed. The data obtained made it possible to estimate the change in particle size at different stages of combustion. An increase in linear dimensions during conversion was achieved of up to 2 times. Particle swelling led to a decrease in mechanical strength and destruction of particles before complete burnout.

Brake-by-wire (BBW) technology is crucial in driverless cars. The BBW technology, which has a faster reaction time and greater stability, can improve passenger safety in driverless cars. BBW technology refers to the removal of some complicated mechanical and hydraulic components from the traditional braking system in favor of using wires to transmit braking signals, which improves braking performance. Firstly, this paper summarized BBW’s development history as well as its structure, classification, and operating principles. Subsequently, various control strategies of the BBW system were analyzed, and the development trend and research status of the motor brake-control strategy and wheel-cylinder pressure-control strategy in the braking force-distribution strategy were analyzed respectively, and the brake fault-tolerance technology and regenerative-braking technology were also analyzed and summarized. Finally, this paper summarized the various technologies of BBW, taking the electromech... [more]

The experimental lipophilicity of fumaric acid (FA) and maleic acid (MA) using the traditional shake-flask method in an n-octanol−water system using reversed-phase thin-layer chromatography (RP-TLC) was determined. Experimental partition coefficients (logPexp) were equal to −0.65 and 0.63 for MA and FA, respectively. The chromatographic lipophilicity (RMW) of the FA and MA was evaluated using reversed-phase thin-layer chromatography on RP8F254s, RP18WF254, and CNF254s plates with a mixture of an organic solvent (methanol or dioxane) and water as the mobile phase. All applied chromatographic conditions were appropriate to determine the lipophilicity of the tested MA and FA. Topological indices derived from distance matrices allowed for the development of a new method for the evaluation of the lipophilicity of MA and FA. All methods applied in this work indicate that MA is less lipophilic than FA. The methods used in this work to determine lipophilicity are of particular importance in th... [more]

Jordan’s energy situation is in a critical state of dependency, with the country relying heavily on imports to satisfy its ever-increasing energy requirements. Renewable energy is a more competitive and consistent source of energy that can supply a large proportion of a country’s energy demand. It is environmentally friendly and minimizes atmospheric pollutant emissions. Thus, bioenergy has the potential to be a crucial alternative energy source in Jordan. Biomass is the principal source of bioenergy; it accounts for approximately 13% of the primary energy demand and is anticipated to supply half of the total primary energy demand by 2050. Nanotechnology has emerged as an important scientific research area with numerous applications, including biofuels. This review summarizes the application of nanoparticles to improve the properties and processes of biofuels. It presents the availability and viability of nanotechnology-supported bioenergy production in Jordan. Jordan generates up to 5... [more]

Orange essential oil (OEO) is mainly composed of D-Limonene and other oxygenated compounds that contribute to the orange flavor and aroma. However, D-Limonene is unstable in the presence of heat, light, and water, affecting the quality of the OEO. Therefore, the objective of this study was to fractionate OEO by distillation, both molecular and fractionated (hybrid), producing a D-Limonene-rich fraction. The OEO was characterized by physicochemical tests and gas chromatography combined with mass spectrometry (GC−MS). The fractionation of the OEO was carried out by molecular distillation and fractional distillation following, in both cases, a factorial design (23) with central points, considering the D-Limonene percentage in the distillate and the residue as a response variable. According to the physicochemical characterization, the predominant optical isomer was dextrorotatory, where D-Limonene is the main component of OEO (92.584%). For molecular distillation, the D-Limonene content wa... [more]

As one of the core pieces of equipment of the thermal power generation system, the economic and environmental performance of a boiler determines the energy efficiency of the thermal power generation unit. The oxygen content in boiler flue gas is an important parameter reflecting the combustion status of the furnace, and accurate prediction of flue gas oxygen content is of great significance for online boiler optimization. In order to solve the online prediction problem of the oxygen content in boiler flue gas, a CNN is applied to build a time series prediction model, which takes the time series samples within a fixed time window as the input of the model and uses several feature extraction modules containing convolutional, activation, and pooling layers for feature extraction and compression, and the model output is the oxygen content in boiler flue gas. Since the oxygen content in boiler flue gas is not only correlated with other variables but also influenced by its own historical tre... [more]

During the operation of a high-speed shear wet granulator, the rotation of the granulation components leads to the emergence of the phenomenon of particle breakage, which results in changes in particle size. To simulate the breakage process of pharmaceutical powder particle agglomerates in a granulator, a Hertz−Mindlin with bonding contact model was designed in this study. The effects of impeller speed, chopper speed, and granulation time on particle breakage were then studied. The results show that the agglomerates formed by the powder particles are not only sheared and collided by the chopper at high speed but also squeezed by the impeller, which causes the powder particles to break. In this paper, 20 sets of case simulations were conducted, and it was found that the impeller significantly affected the fragmentation rate of particles. Increasing the speed of the impeller increases the particle breakage rate and reduces the mean particle size.

Recent work has presented a numerical model of a longwall ventilated by a U-system, considering the real shape of an adjacent goaf in addition to parameters characterizing the distribution of porosity and permeability. Analogous distributions are used in the two-dimensional model implemented in VentZroby software. A comparison of the results of the three-dimensional flow calculations with the two-dimensional calculations can be used to verify the simpler description and evaluate the impact of simplifications on the simulation results. Air flow calculations were carried out using the selected turbulence model. The obtained results present the possibility of conducting extensive numerical calculations for flow problems in underground mines, considering more precise descriptions and the interpretation of the calculation results carried out using a simpler description.

The mechanism and kinetic parameters of the interaction of the FLiNaK−CeF3 melt with water vapors and oxygen in the air atmosphere were determined using Raman and IR spectroscopy, XRD analysis, and thermodynamic modeling of processes. The presence of the 4CeF3(solution) + 6H2O (gas) + O2(gas) = 4CeO2(solid) + 12HF(gas) reaction, which disturbs the fluoride melt homogeneity, was verified in situ by Raman spectroscopy adopted for high-temperature, chemically aggressive fluoride systems. Based on the obtained spectral data, the type of the kinetic equation, order, and rate constant of the chemical reaction were determined. The concentration of cerium dioxide was found to increase linearly in time and a zero reaction order with respect to CeO2 was detected. The change in the concentration of CeO2 over time at T = 510 °C is described by the equation C = 0.085t; the reaction rate constant is 0.085 mol. %∙min−1. The obtained kinetic parameters may be used to model emergencies related with the... [more]