Records Added in August 2023
Records added in August 2023
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Showing records 1 to 25 of 177. [First] Page: 1 2 3 4 5 Last
Application and Comparison of Machine Learning Methods for Mud Shale Petrographic Identification
Ruhao Liu, Lei Zhang, Xinrui Wang, Xuejuan Zhang, Xingzhou Liu, Xin He, Xiaoming Zhao, Dianshi Xiao, Zheng Cao
August 3, 2023 (v1)
Keywords: lithofacies classification, Machine Learning, shale
Machine learning is the main technical means for lithofacies logging identification. As the main target of shale oil spatial distribution prediction, mud shale petrography is subjected to the constraints of stratigraphic inhomogeneity and logging information redundancy. Therefore, choosing the most applicable machine learning method for different geological characteristics and data situations is one of the key aspects of high-precision lithofacies identification. However, only a few studies have been conducted on the applicability of machine learning methods for mud shale petrography. This paper aims to identify lithofacies using commonly used machine learning methods. The study employs five supervised learning algorithms, namely Random Forest Algorithm (RF), BP Neural Network Algorithm (BPANN), Gradient Boosting Decision Tree Method (GBDT), Nearest Neighbor Method (KNN), and Vector Machine Method (SVM), as well as four unsupervised learning algorithms, namely K-means, DBSCAN, SOM, and... [more]
Energy Dissipation and Fracture Mechanism of Layered Sandstones under Coupled Hydro-Mechanical Unloading
Zhixiang Song, Junwen Zhang, Shaokang Wu
August 3, 2023 (v1)
Keywords: “Energy Flow” chain, coupled hydro-mechanical unloading, energy evolution, facture mechanism, rock burst
Rock burst is easy to occur in the water-rich roadway of coal mines, which is closely related to the energy dissipation and fracture mechanism of rocks under coupled hydro-mechanical (H-M) unloading. Therefore, in combination with the triaxial loading and unloading process and H-M coupling effect, the mechanical test of layered sandstones under coupled hydro-mechanical unloading (TLUTP) was conducted. The energy dissipation and fracture mechanism were revealed. The results show that: (1) The influence of layered angles on the peak volumetric strain is more sensitive than that of confining pressure under conventional triaxial loading with H-M coupling (CTLTP). On the contrary, the influence of confining pressure on the peak volumetric strain is more sensitive than that of layered angles under TLUTP. (2) With increasing layered angles, the peak elastic energy density under CTLTP shows the “W” shaped evolution characteristic, while that of under TLUTP shows the “N” shaped evolution charac... [more]
Intelligent Analysis of Vibration Faults in Hydroelectric Generating Units Based on Empirical Mode Decomposition
Hong Tian, Lijing Yang, Peng Ji
August 3, 2023 (v1)
Keywords: BPNN, EMD, noise reduction, signal, vibration fault
Implementing intelligent identification of faults in hydroelectric units helps in the timely detection of faults and taking measures to minimize economic losses. Therefore, improving the accuracy of fault signal recognition has always been a research focus. This study is based on the improved empirical mode decomposition (EMD) theory to study the denoising and feature extraction of vibration signals of hydroelectric units and uses the backpropagation neural network (BPNN) to establish corresponding connections between signal features and vibration fault states. The improved EMD in this study can improve the performance of noise reduction processing and contribute to the accurate identification of vibration faults. The vibration fault identification criteria can adopt three dimensionless feature parameters: peak skewness coefficient, valley skewness coefficient, and kurtosis coefficient of the second- and third-order components of the signal, with recognition rates and accuracy reaching... [more]
Fracture Patterns of Rocks Observed under Cryogenic Conditions Using Cryo-Scanning Electron Microscopy
Qi An, Chunyang Hong, Haitao Wen
August 3, 2023 (v1)
Subject: Materials
Keywords: cryo-scanning electron microscopy, cryogenic fracturing, fracture morphology, reservoir stimulation, thermal shock, unconventional reservoirs
Cryogenic fracturing, which uses liquid nitrogen (LN2) as a fracturing fluid, is a waterless fracturing method. However, previous attempts to investigate the fracture morphology of rocks after LN2 quenching have been mainly based on standard scanning electron microscopy (SEM) analysis at room temperature. This can be problematic since thermally-induced fractures created by temperature difference tend to close as a sample warms and thermal stress relaxes. To address this issue, we established a novel approach employing Cryo-scanning electron microscopy (Cryo-SEM) to investigate the fracture patterns induced by liquid nitrogen quenching under cryogenic conditions. This method can achieve in-situ visualization of fractures and pores with a nano-scale resolution at −190 °C. X-ray computed tomography (CT) is also employed to illustrate the fracture distribution inside samples. Cryo-SEM and standard SEM are compared, and statistical assessments are conducted to quantify fracture aperture siz... [more]
A CFD-Based Methodology for Impact Assessment of Industrial Emissions and Evaluation of Mitigation Measures for Regulatory Purposes
Elena Antuña-Yudego, Víctor Manuel Fernández-Pacheco, Eduardo Álvarez-Álvarez, Juan Luis Carús-Candás, María José Suárez-López
August 3, 2023 (v1)
Keywords: complex terrain scenario, computational fluid dynamics (CFD), industrial emissions plume behaviour, pollutant dispersion
In a context where air quality has become a global concern, modelling techniques are becoming very popular for analysing pollutant dispersion conditions. While models based on empirical formulations are most widely used for industrial scenarios, singular cases involving complex terrain or large obstacles in the vicinity of emission sources require a more robust approach to evaluate the dispersion conditions. In this research, a computational fluid dynamics (CFD) model is developed to analyse the dispersion of pollutants from an industrial facility whose location and characteristics suggest the occurrence of complex flow features that affect the dispersion patterns. In addition, the variation of the gas exit temperatures of waste heat recovery systems is proposed as a measure to mitigate the impact of the plume. The simulation results show unexpected deviations in the plume path affecting vulnerable areas in a nearby mountainside, but increasing the gas exit temperature is useful to pre... [more]
A Fast Density Peak Clustering Method for Power Data Security Detection Based on Local Outlier Factors
Zhuo Lv, Li Di, Cen Chen, Bo Zhang, Nuannuan Li
August 3, 2023 (v1)
Keywords: anomaly detection, density, distance, local outlier factors, power data, principal component analysis
The basic work of power data research is anomaly detection. It is necessary to find a method suitable for processing current power system data. Research proposes an algorithm of fast density peak clustering with Local Outlier Factor (LOF). The algorithm has poor performance in processing datasets with irregular shapes and significant local density changes, and has the disadvantage of strong dependence on truncation distance. This study provides the decision rules for outliers incorporating the idea of LOF. The improved algorithm can fully consider the characteristics of power data and reduce the dependence on truncation distance. In anomaly detection based on the simulation of real power data, the classification accuracy of the improved CFSFDP algorithm is 4.87% higher than that of the traditional algorithm, and the accuracy rate is 97.41%. The missed and false detection rates of the LOF-CFSFDP algorithm are decreased by 2.23% and 2.64%, respectively, compared to the traditional algori... [more]
Biodiesel Production from Waste Cooking Oil Using Different Types of Catalysts
Ayse Hilal Ulukardesler
August 3, 2023 (v1)
Keywords: biodiesel, catalysts, Renewable and Sustainable Energy, transesterification, waste cooking oil
The global energy demand is increasing day by day. Fossil fuels such as crude oil, coal and gas are the main source of energy worldwide. However, fossil fuels, which cause acid rain, the greenhouse effect and other such environmental problems, will eventually be depleted, and renewable energy seems to be the most reasonable solution in this regard. Renewable biofuels have significant potential and can meet the world’s current energy demand. One of the important biofuels is biodiesel, and in the future it can replace petroleum. Waste cooking oil was used as a raw material in biodiesel production in order to reduce the production cost of the offered additive. In this study, the aim was to optimize the process parameters for biodiesel production within the acceptable limit values in the literature. Therefore, the molar ratio of methanol to waste cooking oil (9:1−15:1), catalyst concentration (1−5% by weight) and reaction time (60−120 min) were studied for two catalyst types, potassium hyd... [more]
Special Issue on “Extraction and Purification of Bioactive Compounds”
Qianqian Xu, Zongbi Bao
August 3, 2023 (v1)
Subject: Biosystems
Bioactive compounds, which are abundant in flora, fauna, and microorganisms, can potentially be used by various industries, including pharmaceuticals, functional foods, dietary supplements, and cosmetics [...]
An Efficient Method to Fabricate the Mold Cavity for a Helical Cylindrical Pinion
Bo Wu, Likuan Zhu, Zhiwen Zhou, Cheng Guo, Tao Cheng, Xiaoyu Wu
August 3, 2023 (v1)
Keywords: helical cylindrical pinion, injection mold, LS-WEDM, plastic torsion forming
An efficient method was proposed to fabricate the mold cavity for a helical cylindrical pinion based on a plastic torsion forming concept. The structure of the spur gear cavity with the same profile as the end face of the target helical gear cavity was first fabricated by low-speed wire electrical discharge machining (LS-WEDM). Then, the structure of the helical gear cavity could be obtained by twisting the spur gear cavity plastically around the central axis. In this way, the fabrication process of a helical cylindrical gear cavity could be greatly simplified, compared to the fabrication of a multi-stage helical gear core electrode and the highly difficult and complex spiral EDM process in the current gear manufacturing method. Moreover, several experiments were conducted to verify this novel processing concept, and a theoretical model was established to show the relationship between the machine torsion angle and the helical angle of a helical gear. Based on this theoretical model, th... [more]
Numerical Simulation of Multi-Fracture Propagation Based on the Extended Finite Element Method
Qiquan Ran, Xin Zhou, Jiaxin Dong, Mengya Xu, Dianxing Ren, Ruibo Li
August 3, 2023 (v1)
Keywords: fracture interference, hydraulic fracturing, stress shadow, XFEM
Multi-stage, multi-cluster fracturing in horizontal wells is widely used as one of the most effective methods for unconventional reservoir transformation. This study is based on the extended finite element method and establishes a multi-hydraulic fracturing propagation model that couples rock damage, stress, and fluid flow, and the influence of horizontal stress difference and cluster spacing on fracture propagation is quantitatively analyzed. The simulation results show that changes in horizontal stress differences and inter-cluster spacing have a significant impact on the final propagation morphology of hydraulic fractures, and the change of the fracture initiation sequence forms different stress shadow areas, which in turn affects the propagation morphology of the fractures. When two fractures simultaneously propagate, they will eventually form a “repulsive” deviation, and a smaller stress difference and a decrease in inter-cluster spacing will lead to a more significant deviation o... [more]
Plasma Agricultural Nitrogen Fixation Using Clean Energies: New Attempt of Promoting PV Absorption in Rural Areas
Qiyu Zheng, Liying Li, Zhihua Xue, Yanbin Liu, Dehua Zang, Zifeng Wang, Haowei Qu, Jiaxuan Yin, Lidi Wang
August 3, 2023 (v1)
Keywords: agricultural nitrogen fixation, discharge characteristics, gliding arc discharge, plasma, remote rural areas, solar energy
In recent years, a large number of countries have connected and distributed photovoltaics in remote rural areas, aiming to promote the use of clean energy in rural areas. The solar energy that is not used in time needs to be discarded, resulting in a large amount of wasted energy. Rural areas are closely related to agricultural production, and solar energy can be used for agricultural nitrogen fixation to supplement the nitrogen needed by crops and effectively use the upcoming waste of solar energy. A photovoltaic-driven plasma reactor for nitrogen fixation in agriculture was designed in this study. The air inlet and outlet holes are arranged above and below the reactor to facilitate air entry and directly interact with the gliding arc generated at the bottom of the electrode to achieve atmospheric nitrogen fixation in agriculture. The characteristics of gliding arc development in the process of nitrogen fixation in agriculture were studied experimentally. There are two discharge modes... [more]
Desiccant Technologies for Improving Air Quality: An Overview of the Brazilian Scenario and Comparison of Available Design Software for Manufactured Desiccant Wheels
York Castillo Santiago, Bruno Gomes Nunes, Geovani Souza Fontana, Daiane Busanello, Alexandre Fernandes Santos, Samuel Moreira Duarte Santos, Estefania Neiva de Mello, Leandro A. Sphaier
August 3, 2023 (v1)
Keywords: air conditioning systems, air quality, dehumidification, desiccant wheels
A review of desiccant dehumidification technologies for improving air quality is presented, mainly focusing on alternatives for air conditioning systems for minimizing Sick Building Syndrome. The principles and types of desiccant wheels, as well as the existing selection software for these types of equipment, were reviewed and comparatively evaluated. The study focused on the Brazilian context; thus, information about this country’s air conditioning systems and laws were evaluated. Possible applications of desiccant wheels, such as their integration into cooling cycles and the sensible heat wheel, were also analyzed. Finally, several examples of commercial desiccant wheel selection software that are useful in many situations were evaluated. Nevertheless, it was evidenced that the available software could not perform an operation analysis for only a specific period. Therefore, creating computational tools to select desiccant wheels is essential when considering the data from the differe... [more]
Study on Stimulation Mechanism and Parameter Optimization of Radial Water Jet Drilling Technique in Low Physical Property Sections of Petroleum Reservoirs
Guangsheng Cao, Xi Yi, Ning Zhang, Dan Li, Peidong Xing, Ying Liu, Shengbo Zhai
August 3, 2023 (v1)
Subject: Materials
Keywords: hydraulic fracturing electrical simulation, low materiality section, perforation parameters, radial water jet
Radial drilling-fracturing is an innovative fracturing technology that achieves superior stimulation effects. In order to study the permeability-increasing effect and main influencing factors of radial water jet drilling in the low physical section, this paper uses a fracking electrical simulation experiment, based on the principle of hydropower similarity, to simulate the reservoir conditions and well pattern in the low physical section and, at the same time, establishes the radial fracturing model of the low physical section reservoir, simulates the saturation field, pressure field, and production-change law under different drilling parameters, and studies different influencing factors. The experimental results show that when the number of drilling holes exceeds two, the effect of increasing production gradually becomes less significant as the number of drilling holes increases; Within the range of the angle between the two boreholes, the forward distance of the oil−water displacemen... [more]
Cryogenic Fracture Proliferation from Boreholes under Stresses
Minsu Cha, Naif B. Alqahtani, Lei Wang
August 3, 2023 (v1)
Keywords: cryogenic fracturing, enhanced geothermal system, fracture propagation, hot dry rock, hydraulic fracturing, liquid nitrogen, thermal fracture, thermal shock, thermal stress, unconventional reservoir, well stimulation
Cryogenic fracturing has been explored in recent years as a waterless fracturing method for well stimulation to avoid issues encountered in water-based hydraulic fracturing. Cryogenic stimulation using liquid nitrogen applies large thermal gradients on reservoir rocks to induce fractures. This study investigates the initiation and proliferation of cryogenic fractures from boreholes under external stress on specimens. We flowed liquid nitrogen through boreholes drilled through the center of transparent PMMA cylinders under uniaxial stress and monitored fracture proliferation, temperatures, and borehole pressures. Our results show that the effect of stress resembles that of hydraulic fractures such that fractures propagate more in the direction of the stress. Under loading perpendicular to the borehole axis, a cloud of annular and longitudinal fractures extends more in the direction of loading. Under loading parallel to the borehole axis, longitudinal fractures dominate, and annular frac... [more]
Cluster Optimization for Integrated Energy Systems Considering Multi-Energy Sharing and Asymmetric Profit Allocation: A Case Study of China
Shiting Cui, Peng Wang, Yao Gao, Ruijin Zhu
August 3, 2023 (v1)
Subject: Optimization
Keywords: asymmetric profit allocation, electricity, heat and oxygen coupling, IES cluster optimization, multi-energy sharing, Nash game
This study proposes a novel integrated energy system (IES) cluster optimization structure that uses multi-energy sharing, multi-Nash games, and asymmetric profit allocation according to the energy supply demand and energy development planning for Tibet. First, it integrates clean energy units such as concentrated solar power, power to hydrogen to power, and vacuum pressure swing adsorption to build a novel IES including electricity, heat, and oxygen. Second, multiple novel IESs are combined to form an IES cluster and the IES cluster is divided into three stages of optimization: the first stage is to achieve optimal multi-energy sharing under cluster optimization, the second stage is to conduct multi-Nash games to achieve optimal sharing cost, and the third stage is to conduct asymmetric profit allocation. Finally, the case study is conducted and the results show that the multi-Nash games and asymmetric profit allocation can effectively improve the renewable energy consumption of the IE... [more]
Artificial Neural Networks (ANNs) for Vapour-Liquid-Liquid Equilibrium (VLLE) Predictions in N-Octane/Water Blends
Esteban Lopez-Ramirez, Sandra Lopez-Zamora, Salvador Escobedo, Hugo de Lasa
August 3, 2023 (v1)
Keywords: Artificial Neural Networks, hydrocarbon/water blends, Machine Learning, vapour-liquid-liquid equilibrium
Blends of bitumen, clay, and quartz in water are obtained from the surface mining of the Athabasca Oil Sands. To facilitate its transportation through pipelines, this mixture is usually diluted with locally produced naphtha. As a result of this, naphtha has to be recovered later, in a naphtha recovery unit (NRU). The NRU process is a complex one and requires the knowledge of Vapour-Liquid-Liquid Equilibrium (VLLE) thermodynamics. The present study uses experimental data, obtained in a CREC-VL-Cell, and Artificial Intelligence (AI) for vapour-liquid-liquid equilibrium (VLLE) calculations. The proposed Artificial Neural Networks (ANNs) do not require prior knowledge of the number of vapour-liquid phases. These ANNs involve hyperparameters that are used to obtain the best ANN model architecture. To accomplish this, this study considers (a) R2 Coefficients of Determination and (b) ANN training requirements to avoid data underfitting and overfitting. Results demonstrate that temperature has... [more]
Influence of Gas Inlet Slit Width on Gas-Assisted Plastic Micro-Tube Extrusion
Shuiquan Chen, Xingyuan Huang, Bin Liu, Xiaohui Zhang
August 3, 2023 (v1)
Keywords: extrusion deformation, gas-assisted extrusion, gas–liquid two-phase model, numerical simulation
In the process of the double-layer gas-assisted extrusion of plastic micro-tubes, the external size and surface quality of the micro-tubes are greatly affected by the size of the assisting gas inlet slit inside the mold. Therefore, in this experiment, a two-phase flow model was established based on a compressible gas and a non-compressible melt. The Polyflow finite element solution software module was used to solve the velocity field, temperature field, pressure field, and section size of the melt under the condition of double-layer gas-assisted extrusion in a mold under different gas inlet slit widths. The results show that, with an increase in the width of the gas inlet slit, the melt outlet velocity increases, the surface temperature increases, wall thickness shrinkage increases, and interior diameter expansion increases. In the process of gas-assisted extrusion, the thickness of the air cushion is affected by adjusting the size of the gas inlet slit, and, hence, changes the shape a... [more]
Microwave-Assisted Extraction of Condensed Tannins from Branches of Prunus spinosa L.: Response Surface Modeling and Optimization
Oana Teodora Ciuperca (Apreutesei), Elena Ionescu, Marius Sebastian Secula, Irina Volf
August 3, 2023 (v1)
Keywords: condensed tannins, microwave-assisted extraction, process optimization, Prunus spinosa, response surface modeling, two-level factorial design
The present study was conducted in order to investigate the parameters influencing the extraction of condensed tannins from branches of Prunus spinosa L. as a source of biomass, using a two-level factorial design. The extraction of condensed tannins was performed using microwave assisted-extraction (MAE)—a green technique to produce concentrated and pure extracts. Experimental tests were run to establish the effects of independent variables on the extraction of condensed tannins (expressed as catechin and epicatechin), which were quantified using high-performance thin-layer chromatography−densitometry. Four process variables were evaluated: ethanolic solvent concentration (% v/v) (30, 70), liquid-to-solid ratio (mL/g) (6:1, 10:1), extraction time (min) (2, 5) and microwave power (W) (400, 600). The significant influencing parameters were liquid-to-solid ratio and solvent concentration. The maximum content of condensed tannins (3.4 mg g−1 catechin and 3.45 mg g−1 epicatechin) was obtain... [more]
A Thermal Analysis of LASER Beam Welding Using Statistical Approaches
Ariel Flores Monteiro de Oliveira, Elisan dos S. Magalhães, Luiz E. dos S. Paes, Milton Pereira, Leonardo R. R. da Silva
August 3, 2023 (v1)
Keywords: Compute Unified Device Architecture (CUDA-C), heat transfer simulation, LASER welding, parallel computing, parameter optimization, Taguchi’s design
Implementing input parameters that match the experimental weld shape is challenging in LASER beam welding (LBW) simulation because the computed heat input and spot for temperature acquisition strongly affect the outcomes. Therefore, this study focuses on investigating the autogenous LBW of AISI 1020 using a three-dimensional heat transfer model that assumes a modified Gaussian heat flux distribution depending on LASER power (Qw), radius (R), and penetration (hp). The influence of such variables on the simulated weld bead was assessed through analysis of variance (ANOVA). The ANOVA returns reliable results as long as the data is normally distributed. The input radius exerts the most prominent influence. Taguchi’s design defined the studied data reducing about 65% of the simulations compared to a full factorial design. The optimum values to match the computed outcomes to lab-controlled experiments were 2400 W for power (80% efficiency), 0.50 mm for radius, and 1.64 mm for penetration. Mo... [more]
Evaluating the Efficiency of the Process Safety Management System through Analysis of Major Industrial Accidents in South Korea
Byung-Tae Yoo, Woo Sub Shim
August 3, 2023 (v1)
Keywords: major industrial accidents, process safety management (PSM), process safety report, safety operation plan
The process safety management (PSM) system was introduced in South Korea in 1996, wherein a company voluntarily organizes and manages a chemical accident prevention system, which contributes to reducing chemical accidents. However, large- and small-scale chemical accidents occur frequently. This trend necessitates analysis and improvement of the PSM systems. This study aimed to analyze the correlation between major industrial accidents, their main causes, the status of accidents by company size and industry, and the PSM evaluation grade through an analysis of 130 accidents that occurred in the past 17 years (2005−2021). The results showed that small- and medium-sized enterprises (SMEs) with fewer than 100 employees accounted for 36% of all accidents, indicating a higher occurrence rate than large companies. Additionally, the proportion of companies with inadequate PSM levels, rated as M-grade (M+, and M−), were 67.0%, suggesting a high probability of major industrial accidents. The res... [more]
Efficient Multi-Objective Optimization on Dynamic Flexible Job Shop Scheduling Using Deep Reinforcement Learning Approach
Zufa Wu, Hongbo Fan, Yimeng Sun, Manyu Peng
August 3, 2023 (v1)
Keywords: deep reinforcement learning, delay time sum, dual layer deep Q-network, dynamic flexible job shop scheduling, global optimum, makespan, multi-objective optimization
Previous research focuses on approaches of deep reinforcement learning (DRL) to optimize diverse types of the single-objective dynamic flexible job shop scheduling problem (DFJSP), e.g., energy consumption, earliness and tardiness penalty and machine utilization rate, which gain many improvements in terms of objective metrics in comparison with metaheuristic algorithms such as GA (genetic algorithm) and dispatching rules such as MRT (most remaining time first). However, single-objective optimization in the job shop floor cannot satisfy the requirements of modern smart manufacturing systems, and the multiple-objective DFJSP has become mainstream and the core of intelligent workshops. A complex production environment in a real-world factory causes scheduling entities to have sophisticated characteristics, e.g., a job’s non-uniform processing time, uncertainty of the operation number and restraint of the due time, avoidance of the single machine’s prolonged slack time as well as overweigh... [more]
Extraction of Vanadium from the Spent Residuum Hydroprocessing Catalysts by Fenton-like Reaction Followed with Alkaline Leaching
Yuefen Lv, Ge Zhao, Cailong Shen, Yanzhen Chen, Yiqun Fan, Guangji Zhang, Chao Yang
August 3, 2023 (v1)
Subject: Environment
Keywords: alkali leaching, Fenton-like reaction, oil removal, spent residuum hydroprocessing catalyst, vanadium
Spent residuum hydroprocessing (RHDP) catalysts are hazardous waste bearing high-content vanadium and large amounts of oily pollutants. In this paper, a process featuring a Fenton-like reaction and alkaline leaching was proposed to recover vanadium from spent RHDP catalysts. In the first step, a Fenton-like reaction using peroxide was conducted to degrade the oily pollutants and make the surface of the spent catalyst becomes hydrophilic. In the second step, the vanadium-containing deposit on the catalyst was leached with 0.5 M Na2S2O8 at 70 °C for transforming vanadium sulfide to oxide in 5 h. In the last step, alkaline leaching was employed to dissolve vanadium from the oxidizing residue at 80 °C for 1 h. It was found that the accumulated leaching efficiency of vanadium can reach up to 90.92%, and only a small part of aluminum and sulfur was dissolved. These results indicated that this combined process can extract vanadium selectively from spent residuum hydroprocessing catalysts unde... [more]
Nonlinear Adaptive Back-Stepping Optimization Control of the Hydraulic Active Suspension Actuator
Lizhe Wu, Dingxuan Zhao, Xiaolong Zhao, Yalu Qin
August 3, 2023 (v1)
Keywords: controller parameter optimization, crazy particles, hydraulic active suspension actuator, nonlinear adaptive back-stepping control, performance indicator function, time-varying acceleration coefficients
The displacement tracking performance of the electro-hydraulic servo actuator is critical for hydraulic active suspension control. To tackle the problem of slow time-varying parameters in the existing actuator dynamics model, a nonlinear adaptive back-stepping control (ABC) approach is adopted. Simultaneously, the parameters of the nonlinear ABC are difficult to configure, resulting in a poor control effect. An enhanced particle swarm optimization (PSO) approach integrating crazy particles (CP) and time-varying acceleration coefficients (TVAC) is suggested to optimize the controller settings. Furthermore, in order to obtain satisfactory dynamic characteristics of the transition process, the absolute value of the error time integral performance index is used as the minimum performance index function of parameter selection, and the square term of the control input is added to the performance index function to prevent excessive controller energy. Finally, it can be observed from the simul... [more]
Investigation of the Interface Effects and Frosting Mechanism of Nanoporous Alumina Sheets
Song He, Heyun Liu, Yuan Zhang, Haili Liu, Wang Chen
August 3, 2023 (v1)
Subject: Environment
Keywords: frosting, interface effect, mechanism, nanoporous alumina sheet
Nanoporous alumina sheets can inhibit the growth of the frost layer in a low-temperature environment, which has been widely used in air-conditioning heat exchangers. In this study, nanoporous alumina sheets with pore diameters of 30 nm, 100 nm, 200 nm, 300 nm, and 400 nm were prepared by using the anodic oxidation method with the conventional polished aluminum sheet as the reference. A comprehensive and in-depth analysis of the frosting mechanism has been proposed based on the contact angle, specific surface area, and fractal dimension. It was found that compared with the polished aluminum sheet, the nanoporous alumina sheets had good anti-frost properties. Due to its special interface effects, the porous alumina sheet with a 100 nm pore diameter had strong anti-frost performance under low temperatures and high humidity. In an environment with low surface temperature and high relative humidity, it is recommended to use hydrophilic aluminum fins with large specific areas and small fract... [more]
Application of the Hybrid Chemical-Biocatalytic Approach for Conversion of Nitrocellulose-Containing Sewage Sludge
Sergey Gaydamaka, Marina Gladchenko, Olga Maslova, Olga Senko, Alla Kornilova, Igor’ Kornilov
August 3, 2023 (v1)
Subject: Materials
Keywords: anaerobic processes, biogas, denitrification, hybrid catalysis, nitrocellulose, waste
Waste containing explosive chemicals are hazardous to the environment. We suggested and implemented a hybrid approach for the destruction of nitrocellulose-containing sewage sludge (NCS) from a real chemical industrial complex. Combining chemical alkaline hydrolysis and mesophilic anaerobic digestion in a up-flow anaerobic sludge blanket (UASB) reactor allowed us to successfully achieve the balance between the environmental safety and economic efficiency of the stages of the treatment. After the alkaline treatment of waste at 50 °C with 1.5 M KOH, the solid residue contained mostly just sand and no nitrocellulose (NC). The liquid phase accumulated 2869 ± 24 mg N-NO2−/L and 1698 ± 51 mg N-NO3−/L. Bioconversion of the liquid phase neutralized with acetic acid and diluted with water by a factor of 50 in a 1 L UASB reactor ensured 99% efficiency of extracting N(NO2− + NO3−) and chemical oxygen demand (COD). Further, biogas with high methane content (>70%) was obtained. The establishment of... [more]
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