Due to improved mechanical properties, nano-alumina (NA) addition has been considered as an interesting method to promote the performance of cement composites. To investigate the enhancing effect of NA on the fire resistance of cement-based composites, the physical and mechanical properties of NA-modified cement composites (NAMCCs) were experimentally measured after exposure to high temperatures (up to 800 °C). The variation mechanism of the physical properties of NAMCCs with increasing temperature was explored using X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. Increasing temperature leads to a gradual decrease in density and ultrasonic wave velocity but an overall increase in mass loss. The addition of NA particles effectively improved the mechanical properties of hardened cement pastes after heat treatment at all the temperatures studied. The compressive strength, elastic modulus and flexural strength all gradually decrease with increasing temperature. Comb... [more]

Backstepping-based fixed-time tracking control is proposed for a robotic arm system to solve the problem of trajectory tracking control under system uncertainties, which ensures the robotic arm system can realize stable tracking control within a fixed time independent of the initial state of the system. In addition, to address the uncertainties in the robotic arm system, a control strategy based on disturbance observer compensation is designed, which provides feed-forward compensation through the accurate estimation of the system uncertainties and enhances the system’s robustness. Finally, a two-link robotic arm model is used for simulation experiments, and the comparison results show that the control scheme designed in this article can effectively improve the robotic arm’s tracking accuracy and convergence speed.

A series of theoretical and experimental studies was carried out with the aim of a direct comparison of the thermal and microwave destruction of peat during pyrolysis. Different heating mechanisms in these processes were investigated in the framework of simulations conducted using a commercial 3D software package, CST Studio Suite, to define their specific features. Based on these simulations, identical reactors were constructed exploiting an electric element and a microwave complex as a heat source, and an experimental technique was developed that allows these processes to be correctly compared under similar conditions. Using these reactors based on different heat sources, comparative experiments on peat pyrolysis were performed, and the results of the theoretical analysis were confirmed. As a result, the advantages of microwave exposure were demonstrated to achieve a more uniform and deep fragmentation of peat, increase the reaction rate and reduce the processing time, with high ener... [more]

Due to the growth in the consumption of avocado in recent years, the amount of waste caused by avocado peel and seed has increased. Avocado waste can be transformed into valuable products such as energy, biofuels, and biological products using integrated processes in a biorefinery. This paper considers the detailed modeling, simulation, and optimization of a biorefinery for the production of phenolic compounds, bioethanol, biological xylitol, syngas, and electrical power from avocado seed and peel, using Aspen Plus in equation-oriented mode as a process simulation tool. For a biorefinery in nominal conditions, it is possible to achieve a gross profit of approximately 30×106 USD/year for capital costs of USD 31.4×106, while the combined effect of process optimization and heat integration allows reaching a gross profit of 37×106 USD/year for capital costs of USD 30.7×106. These results of the optimized plant show its potential to take advantage of avocado seed and peel in a profitable an... [more]

Reducing carbon emissions and increasing the integration of new energy sources are key steps towards achieving sustainable development. Virtual power plants (VPPs) play a significant role in enhancing grid security and promoting the transition to clean, low-carbon energy. The core equipment of the VPP, the CHP unit, utilizes a thermal engine or power station to generate electricity and useful heat simultaneously. However, the intermittent and volatile nature of renewable energy sources, as well as the “heat-driven power generation” mode of combined heat and power (CHP) units, presents contradictions that severely affect their peak-shifting capability and lead to high carbon emissions. To address these issues, a novel VPP is established by integrating traditional power plants with carbon capture and hydrogen energy storage. This approach utilizes a “hydrogen energy storage−electric boiler” decoupling method to address the operational mode of CHP, strengthens the coupling relationship be... [more]

Solar photovoltaic (PV) generation will play a crucial role in the global clean energy transition toward carbon neutrality. While the development of solar PV generation has been explored in depth, the development of high-proportion solar PV generation has yet to be discussed. Considering the back force of the constraint of achieving carbon neutrality within the specified timeframe, this paper establishes a unified, multi-dimensional, and achievable framework through which to perform a system analysis for exploring the potential risks and challenges involved in the development process of high-proportion solar PV generation and investigating possible pathways to fostering the development of high-proportion solar PV generation. The results show that the critical risks and challenges include a low conversion efficiency, poorer resource endowment, more limited land resources, a low use of rooftop resources, an increasing complexity of power system scheduling, and low public awareness. These... [more]

Three-compartment septic tanks are a prominently advocated environmentally sustainable sanitation facility in rural China. However, the comprehensive elimination efficacy and underlying mechanisms of pathogenic bacteria within septic tanks remain incompletely understood. In particular, the operational performance in low-temperature conditions has received limited attention in the existing literature. In this work, a simulation of the three-compartment septic tank treatment system was conducted under low-temperature conditions (15 °C). The operational results exemplify the synergistic interplay of volatile fatty acids (VFAs), NH3-N, and bacterial communities, culminating in a partial reduction in Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis, within the three-compartment septic tank. Their respective population abundances were decreased by magnitudes of 2.2, 1.3, 0.03, and 1.46 logarithmic units (copies/mL), respectively. Through the utilizat... [more]

A prevalent metal surface defect is hot-rolled iron oxide; thus, it is critical to regulate the production and growth of oxidized iron during the hot-rolling process. To analyze the influence of Si content on the growth laws of the oxidized layer in carbon steel during heating, three types of carbon steel with significant differences in Si content were selected for research on the growth laws of the oxidized layer at different heating temperatures. The production law and micromorphology of the oxidized layer were analyzed using methods such as scanning electron microscopy and thermodynamic phase diagram calculation, and an oxidation dynamic model was obtained. The predicted control values of the model are highly consistent with the measured values. This study reveals that the heating temperature significantly impacts the thickness of the oxidized layer of carbon steel. At temperatures below 500 °C, the oxidation is not evident, and the layer is thin. Between 500 °C and 900 °C, the stee... [more]

The problems of large deformations, failures, and fractures that agricultural tillage tools may encounter during the cultivation process has long been a concern in the field of agricultural machinery design and manufacturing. It is important to establish a more accurate numerical model to effectively predict tools’ plastic deformation failures and ductile fracture failures. This research develops a numerical model for predicting the plastic deformation failure and ductile fracture failure of agricultural tillage tools using the smoothed particle hydrodynamics (SPH) method and the Johnson−Cook constitutive model. The model uses the Drucker−Prager criterion to describe the elastic−plastic constitutive behavior of the soil, the von Mises criterion to describe the Johnson−Cook constitutive model of the tool, and the coupling condition with the Lennard-Jones repulsive force to describe the interaction between the tool and soil. The numerical results show that the proposed model can effectiv... [more]

The treatment of chabazite (CHA), a natural zeolite, with the alkaline hydrothermal method to improve its ion-exchange capacity is a widely adopted route by environmental scientists for the purpose of better ammonium (NH4+) removal from wastewater. This work addresses a noteworthy trend in environmental science, where researchers, impressed by the increased ion-exchange capacity achieved through alkaline hydrothermal treatment, often bypass the thorough material characterization of treated CHA. The prevalent misconception attributes the improved features solely to the parent zeolitic framework, neglecting the fact that corrosive treatments like this can induce significant alterations in the framework and those must be identified with correct nomenclature. In this work, alkaline-mediated hydrothermally treated CHA has been characterized through X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), solid-state magic-angle spinning nuclear magnetic resonance (MAS... [more]

Currently, the focus of integrated energy system scheduling research is the multi-objective’s optimized operational strategies that take into account the economic benefits, carbon emissions, and new energy consumption rates of such systems. The integration of electric trucks with battery charging and swapping capabilities, along with their corresponding battery swapping stations, into an integrated energy system can not only optimize system operation, but also reduce investment costs associated with building energy storage equipment. This study first constructs an operational model for the electric trucks, as well as an electric truck battery swapping station, of the flexible charging and discharging; then, an optimized scheduling model of an integrated energy system is proposed, including an electric truck battery swapping station and using stepped carbon trading. On the basis of meeting the charging and battery swapping needs of electric trucks and coordinating the system’s electrica... [more]

Alpha particle-emitting radiopharmaceuticals are in high demand for use in targeted alpha therapy. Ac-225 is currently produced using Th-229, but its annual production remains low, approximately 63 GBq. Previously, we produced a large amount of Ac-225 via the (n,2n) reaction in fast reactors; however, it required repetitive irradiation. In this work, we investigated a method to produce Th-229 via the (3n,x) reaction through long-term irradiation using neutrons from Pressurized Water Reactors. As target nuclides, Ra-226, which is commonly used for Ac-225 production, and Th-230, which is not widely used but is abundant, were selected. The evaluation was conducted under mixed conditions of Th-230 and Th-232. Ra-226 and Th-230 produce Th-229 (T1/2 = 7920 years) after long-term neutron irradiation. Th-229, which has a long half-life, the α-decays to produce Ra-225, and the β-decays of Ra-225 to produce Ac-225. These processes are semi-permanent owing to the long half-life of Th-229. Further... [more]

Considering energy conversion efficiency, pollution emissions, and economic benefits, combining biomass with fossil fuels in power generation facilities is a viable approach to address prevailing energy deficits and environmental challenges. This research aimed to investigate the thermodynamic and exergoeconomic performance of a novel power and cooling cogeneration system based on a natural gas−biomass dual fuel gas turbine (DFGT). In this system, a steam Rankine cycle (SRC), a single-effect absorption chiller (SEAC), and an organic Rankine cycle (ORC) are employed as bottoming cycles for the waste heat cascade utilization of the DFGT. The effects of main operating parameters on the performance criteria are examined, and multi-objective optimization is accomplished with a genetic algorithm using exergy efficiency and the sum unit cost of the product (SUCP) as the objective functions. The results demonstrate the higher energy utilization efficiency of the proposed system with the therma... [more]

FeNi films were prepared using the DC magnetron sputtering technique with an oblique deposition arrangement. Multilayers with different orientations of the magnetic anisotropy axes were obtained thanks to a rotary sample holder inside the vacuum chamber. Magnetic properties were studied using magneto−optical Kerr microscopy and a vibrating sample magnetometer. Single-layered FeNi films having thicknesses as high as 10 nm and 40 nm show in-plane uniaxial easy magnetization axes produced by the oblique incidence of incoming components of the beams. Magnetic anisotropy field for four-layered samples with orthogonal uniaxial magnetic anisotropy axes in the adjacent layers and the thickness of individual layers of 10 nm and 40 nm turned out to be less than in single-layered films. The magnetic properties peculiarities of the eight-layered sample FeNi (10 nm) × 8 obtained by rotation of the sample holder by 45° before deposition of each subsequent layer suggest the formation of a helix-like... [more]

The automotive air conditioning (AC) electromagnetic clutch plays a crucial role in accurately controlling power transmission between the engine and the compressor, ensuring the proper operation of the AC system. The aim of this paper is to provide high-quality experimental data for researchers who are interested in simulating the dynamic process of an AC electromagnetic clutch and also to assess the adaptiveness of empirical equations to describe the AC electromagnetic clutch performance that is limited in discussion in existing studies. In this study, an automotive AC electromagnetic clutch characteristic test system was employed along with an infrared (IR) camera to conduct comprehensive experimental analyses. The test system enabled the evaluation of various parameters, including the clutch torque output, compressor exhaust pressure, and temperature of the friction surface. The results revealed that the torque and exhaust pressure were closely associated with the on/off time and ro... [more]

Parallel seam welding (PSW) is the most commonly employed encapsulation technology to ensure hermetic sealing and to safeguard sensitive electronic components. However, the PSW process is complicated by the presence of multiphysical phenomena and nonlinear contact problems, making the analysis of the dynamics of the PSW process highly challenging. This paper proposes a multiphysics simulation model based on direct coupling, enabling the concurrent coupling of the electric field, temperature field, and structural field to facilitate the analysis of the thermal and electrical dynamics within the PSW process. First, this paper conducts an in-depth theoretical analysis of thermal and electrical contact interactions at all contact interfaces within the PSW process, taking into account material properties related to temperature. Second, the acquired data are integrated into a geometric model encompassing electrode wheels and ceramic packaging components, facilitating a strongly coupled multi... [more]

The integration of distributed power generation mainly consisting of photovoltaic and wind power into active distribution networks can lead to safety accidents in grid operation. At the same time, climate change can also cause voltage fluctuations, direct current injection, harmonic pollution, frequency fluctuations, and other issues. To achieve economic and safe operation of the distribution network, an active distribution network-network planning model considering the dynamic configuration of energy storage system energy storage is constructed. This model focuses on energy storage batteries with high ease of use, high modularity, and strong mobility. The route location planning involving different load operating scenarios in spring, summer, autumn, and winter is constructed. The objective function includes the revenue from selling electricity in the distribution network, the expenditure on purchasing electricity in the distribution network, and the cost during the planned constructio... [more]

During the production of soy milk, a by-product is produced, which is typically treated as a waste material. This by-product has significant levels of dietary fibre, proteins, isoflavones and antioxidant capacity. As such, it has been recommended as an effective functional ingredient when milled to a flour after drying at 100 °C. The shelf-life stability of this dried by-product is relatively unknown when stored under different storage conditions (2 °C, 20 °C and 40 °C) and initial moisture content (9%, 12% and 14%), both packaged and exposed to immediate environments. This study investigated the impact of storage over ten weeks on the physical properties, lipid oxidation, antioxidant capacity and stability of isoflavones of this functional ingredient. The results showed that exposure significantly affected the stability of flour, especially on moisture content, water activity, isoflavone concentration and lipid oxidation. Different initial moisture contents significantly affected the... [more]

An overview of the composition of wolframite ores of the Akchatau deposit and the technologies for processing concentrates using NaOH and Na2CO3 by hydro- and pyrometallurgical methods is given, and the disadvantages associated with both the technology and the equipment are noted. To develop a technology for processing Akchatau wolframite concentrates, samples of ore materials were taken, the chemical and mineralogical composition of the samples was studied, and enrichment was carried out to obtain rich concentrates. The kinetics of the sintering of the wolframite concentrate with soda was investigated, the dependences of the degree of transformation of the tungsten minerals into sodium tungstate were obtained, and the rate constants, the order of the reaction, and the values of the apparent activation energy were calculated. The results of sintering an enlarged sample of wolframite concentrate with soda in a muffle furnace are presented. After the subsequent leaching, studies were car... [more]

In the study of borehole instability, the majority of input parameters often rely on the average values that are treated as fixed values. However, in practical engineering scenarios, these input parameters are often accompanied by a high degree of uncertainty. To address this limitation, this paper establishes a borehole stability model considering the uncertainty of input parameters, adopts the Monte Carlo method to calculate the borehole stability reliability at different drilling fluid densities, evaluates the sensitivity of borehole instability to a single parameter, and studies the safe drilling fluid density window at different borehole stability reliability values under multi-parameter uncertainties. The results show that the uncertainty of rock cohesion has a great influence on the fracture pressure of the vertical and horizontal wells. The minimum horizontal stress has the greatest influence on the fracture pressure of the vertical and horizontal wells, followed by pore pressu... [more]

The utilization of auxiliary tools employing ultrasonic high-frequency vibration to enhance rock breaking efficiency holds significant potential for application in underground hard rock excavation engineering. To investigate the failure mechanism of rocks under high frequency ultrasonic vibration load, this study employs particle flow software PFC2D for numerical simulation. By incorporating boundary conditions from actual ultrasonic vibration rock breaking experiments and utilizing a parallel bond model to construct the rock, we analyze the deformation, damage, fracture, and energy evolution process of hard rocks subjected to vibrational loads. The results demonstrate that the maximum displacement in hard rocks increases nearly linearly with vibrations until reaching 5.0199 × 10−3 m, after which it plateaus. Additionally, macroscopic fissures formed during rock failure exhibit an X-shaped pattern. Furthermore, based on our model, we examine the impact of amplitude variation on hard ro... [more]

Knowledge of the chemical changes caused during plasma treatment is essential to enhance food quality. In this work, the influence of two cold plasma technologies, dielectric barrier discharge plasma and glow discharge plasma, on the phenolic profile of araça-boi (Eugenia stipitata) juice was investigated and assessed by gas chromatography coupled to mass spectrometry. Eight phenolic compounds were identified in araça-boi, with cinnamic acid being the major phenolic compound of the fruit juice, followed by protocatechuic acid. The effects of excitation frequency and plasma flow rate were evaluated because these are the main operating conditions that can be set for plasma treatments. The phenolic profile slightly changed due to the reaction of the phenolics with the reactive plasma species produced during the treatment, with the highest increase in phenolic content observed in the dielectric barrier discharge plasma operating at 1000 Hz. Both plasma systems increased the bioavailability... [more]

Solid−liquid flows are encountered in various industrial and natural environments. The internal structure of such flows is highly sensitive to the grading of the solid particles present. In this experimental study, an extended stereometric method is employed to assess the distributions of velocity of particles of different fractions, distinguished by different colors, in vertical and nearly horizontal granular flows. In the vertical flow experiments, mixtures comprising three fractions of lightweight particles, characterized by a very similar density, size, and shape, were tested. The results affirmed the method’s ability to discern particle velocity differences on the order of millimeters per second, establishing its suitability for characterizing nearly horizontal open-channel flows with bimodal mixtures that are stratified and exhibit more complex velocity distributions. Tilting flume experiments, incorporating additional measurements of water velocity distribution, allowed for the... [more]

Hydraulic vibrations in Francis turbines caused by cavitation profoundly impact the overall hydraulic performance and operational stability. Therefore, to investigate the influence of cavitation phenomena under high-load conditions, a three-dimensional unsteady numerical simulation is carried out for a Francis turbine with different head operating conditions, which is combined with the SST k-w turbulence model and two-phase flow cavitation model to capture the evolution of cavitation under high-load conditions. Additionally, utilizing entropy production theory, the hydraulic losses of the Francis turbine during cavitation development are assessed. Contrary to the pressure-drop method, the entropy production theory can quantitatively reflect the characteristics of the local hydraulic loss distribution, with a calculated error coefficient τ not exceeding 2%. The specific findings include: the primary sources of energy loss inside the turbine are the airfoil cavitation and cavitation vort... [more]

This paper studies an improved super-twisting sliding mode controller (IST-SMC) for the permanent magnet synchronous generator (PMSG) voltage loop to improve the anti-disturbance capability of the system. Compared to conventional voltage controllers, the control algorithm provides advantages in terms of system resistance to load disturbances. Conventional voltage controllers have significant voltage fluctuations and long recovery times during sudden load changes. To solve this problem, a voltage loop controller based on a super-twisting sliding mode (ST-SMC) is designed to enhance the immunity of the system. Also, the ST-SMC was improved to further increase the convergence rate of the system and enhance the dynamic performance. The convergence of the system away from the balance point is accelerated by introducing an exponential term, which in turn provides an improvement in the dynamic performance of the system. The effectiveness of the proposed control scheme was verified on a PMSG.