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A Novel Hybrid Optimization Approach for Fault Detection in Photovoltaic Arrays and Inverters Using AI and Statistical Learning Techniques: A Focus on Sustainable Environment
Ahmad Abubakar, Mahmud M. Jibril, Carlos F. M. Almeida, Matheus Gemignani, Mukhtar N. Yahya, Sani I. Abba
November 30, 2023 (v1)
Keywords: Artificial Intelligence, boosted tree algorithms, Elman neural network, Fault Detection, Gaussian processes regression, multi-layer perceptron, sustainable development
Fault detection in PV arrays and inverters is critical for ensuring maximum efficiency and performance. Artificial intelligence (AI) learning can be used to quickly identify issues, resulting in a sustainable environment with reduced downtime and maintenance costs. As the use of solar energy systems continues to grow, the need for reliable and efficient fault detection and diagnosis techniques becomes more critical. This paper presents a novel approach for fault detection in photovoltaic (PV) arrays and inverters, combining AI techniques. It integrates Elman neural network (ENN), boosted tree algorithms (BTA), multi-layer perceptron (MLP), and Gaussian processes regression (GPR) for enhanced accuracy and reliability in fault diagnosis. It leverages its strengths for the accuracy and reliability of fault diagnosis. Feature engineering-based sensitivity analysis was utilized for feature extraction. The fault detection and diagnosis were assessed using several statistical criteria includi... [more]
Finite Element Modelling and Experimental Validation of the Graphite Cutting Process
Dayong Yang, Furui Wei, Wei Wang, Yuchen Zhang, Lingxin Zeng
November 30, 2023 (v1)
Subject: Materials
Keywords: chip morphology, crack initiation and growth, finite element modelling, graphite, machined surface morphology
Graphite is extensively used in the engineering field due to its unique properties, and the study of its cutting mechanism has become particularly important. However, the brittle fracture mechanism of graphite makes it rather easy for cracks with a unique pattern of initiation and growth to develop when processing. Herein, the ABAQUS was selected to establish a finite element model (FEM) of the graphite cutting process. The internal crystal structure of graphite was modelled by a Voronoi structure, and a cohesion unit was globally embedded into the solid unit to simulate crack initiation and growth. In addition, the complete process of chip formation and removal was demonstrated. The analysis of the simulation results showed that the graphite material underwent three periodic cycles of material removal during the cutting process, i.e., large, tiny, and small removal stages. Meanwhile, the simulation results indicated that when ac was large enough, the crack gradually grew inside the gr... [more]
Numeric Investigation on the Stability of a Preformed Roadway under Backfill Body Subjected to Blasting Load
Hongwei Deng, Fei Wu, Renze Ou
November 30, 2023 (v1)
Keywords: backfill body, blasting-induced damage, dynamic response, mine pillar recovery, preformed roadway
Tungsten, essential in the industrial, military, and civilian domains and deemed a strategic resource by various nations, necessitates careful consideration in room and pillar mines due to the potential instability and safety hazards posed by untouched mine pillars, making tungsten recovery crucial for worker safety and economic gain. This research aims to provide guidance for recovering tungsten from mine pillars and making mining operations safer for workers in the Xianglushan mine. Numerical simulations are conducted to study the mechanical response of a preformed roadway in a backfill body subjected to static and dynamic loads with various explosive distances and positions. Blasting vibration velocity and blasting-induced damage in the backfill body are extracted to evaluate the mechanical response of the backfill body. The numerical results indicate that the steel frame and preformed roadway remain stable under the influence of both gravity and the impact from blasting, using a ch... [more]
A Simple Strategy for the Simultaneous Determination of Dopamine, Uric Acid, L-Tryptophan and Theophylline Based on a Carbon Nano-Onions Modified Electrode
Rui An, Wenzhu Kuang, Zijian Li, Tiancheng Mu, Hongxia Luo
November 30, 2023 (v1)
Subject: Materials
Keywords: carbon nano-onions, dopamine, electrochemical sensing, glassy carbon electrode, L-tryptophan, theophylline, uric acid
In this work, carbon nano-onions (CNOs) with particle sizes of 5−10 nm were prepared by the multi-potential step method. High-resolution transmission electron microscopy, infrared spectroscopy and Raman spectroscopy characterize the effective synthesis of CNOs. CNOs/GCEs were prepared by depositing the prepared CNOs onto glassy carbon electrodes (GCEs) by a drop-coating method. Examination of the electrocatalytic activity of the CNOs/GCE sensor by simultaneously detecting dopamine (DA), uric acid (UA), L-tryptophan (Trp) and theophylline (TP) using a differential pulse voltammetry technique. The results showed that the linear ranges of DA, UA, Trp and TP were DA 0.01−38.16 μM, UA 0.06−68.16 μM, Trp 1.00−108.25 μM, and TP 8.16−108.25 μM, and the detection limits (S/N = 3) were 0.0039 μM, 0.0087 μM, 0.18 μM and 0.35 μM, respectively. The CNOS/GCE sensor had good stability and could be used for the detection of actual samples.
Multi-Sized Granular Suspension Transport Modeling for the Control of Lost Circulation and Formation Damage in Fractured Oil and Gas Reservoirs
Jinhua Liu, Yayun Zhang, Dujie Zhang, Fan Li, Hexiang Zhou, Chengyuan Xu, Weiji Wang
November 30, 2023 (v1)
Keywords: fractured reservoir, gas and geothermal resources, multi-sized granule retention, oil, permeability damage, production enhancement, suspended granule transport
Transport and retention of multi-sized suspended granules are common phenomena in fracture media of oil, gas and geothermal reservoirs. It can lead to severe permeability damage and productivity decline, which has a significant impact on the efficient development of underground resources. However, the granule transport and retention behaviors remain not well understood and quantified. The novel stochastic model is proposed for the multi-sized suspended granule transport in naturally fractured reservoirs accounting for granule retention and fracture clogging kinetics. A percolation fracture network is proposed considering fracture connectivity evolution during suspended granule transport. Granule retention and fracture clogging dynamics equations are proposed to account for incomplete fracture clogging by retained granules. The microscale stochastic model is allowed for upscaling to predict the multi-sized granule transport behavior in naturally fractured reservoirs. The model solution... [more]
Numerical Study on the Separation Performance of Hydrocyclones with Different Secondary Cylindrical Section Diameters
Duanxu Hou, Peikun Liu, Qiang Zhao, Lanyue Jiang, Baoyu Cui, Dezhou Wei
November 30, 2023 (v1)
Keywords: hydrocyclone, particle circulation flow, secondary-cylindrical section, separation performance
The particle motion behavior in hydrocyclones has received increasing attention, but the particle circulation flow has received relatively limited attention. In this paper, the particle circulation flow is regulated by changing the secondary-cylindrical section diameter to optimize the separation effect. The effects of secondary-cylindrical section diameters on flow field characteristics and separation performance are explored using the two-fluid model (TFM). The findings demonstrate that particle circulation flows are ubiquitous in the secondary-cylindrical hydrocyclone and are induced by the axial velocity wave zone. The increase in the secondary-cylindrical section diameter intensifies the coarse particle circulation and aggrandizes the coarse particle’s aggregation degree and aggregation region, leading to an increment in cut size. The circulation flow component can be regulated by adjusting the secondary-cylindrical section, thus improving the classification effect. An appropriate... [more]
A Fault Warning Approach Using an Enhanced Sand Cat Swarm Optimization Algorithm and a Generalized Neural Network
Youchun Pi, Yun Tan, Amir-Mohammad Golmohammadi, Yujing Guo, Yanfeng Xiao, Yan Chen
November 30, 2023 (v1)
Keywords: Fault Detection, generalized neural network, industrial systems, Machine Learning, sand cat swarm optimization
With the continuous development and complexity of industrial systems, various types of industrial equipment and systems face increasing risks of failure during operation. Important to these systems is fault warning technology, which can timely detect anomalies before failures and take corresponding preventive measures, thereby reducing production interruptions and maintenance costs, improving production efficiency, and enhancing equipment reliability. Machine learning techniques have proven highly effective for fault detection in modern production processes. Among numerous machine learning algorithms, the generalized neural network stands out due to its simplicity, effectiveness, and applicability to various fault warning scenarios. However, the increasing complexity of systems and equipment presents significant challenges to the generalized neural network. In real-world scenarios, it suffers from drawbacks such as difficulties in determining parameters and getting trapped in local opt... [more]
Pneumatic Noise Study of Multi-Stage Sleeve Control Valve
Jianbo Jia, Yan Shi, Xianyu Meng, Bo Zhang, Dameng Li
November 30, 2023 (v1)
Keywords: aerodynamic noise, computational fluid dynamics (CFD), control valve, flow field, sound field
This study considers the practical issue of severe noise observed in a multi-stage sleeve control valve within an engineering project. Employing computational fluid dynamics (CFD) methodology, we initially performed numerical simulations to analyze the steady-state flow field within the control valve. Subsequently, we identified the underlying factors contributing to the noise issue within the valve. To assess the aerodynamic noise of the control valve, we applied the FW-H acoustic analogy theory and determined the intensity and distribution characteristics of the aerodynamic noise. Finally, we validated the numerical simulation results of the aerodynamic noise against theoretical calculations. Our findings indicate that the steam medium experiences high-speed flow due to disturbances caused by various components within the valve, resulting in significant turbulence intensity. This intense turbulence leads to pressure fluctuations in the steam, serving as the main catalyst for noise ge... [more]
Molecular Modeling of Supercritical Processes and the Lattice—Gas Model
Yuri Konstantinovich Tovbin
November 30, 2023 (v1)
Keywords: lattice gas model, non-ideal reaction systems, supercritical conditions, theory of the absolute rate of a reaction
The existing possibilities for modeling the kinetics of supercritical processes at the molecular level are considered from the point of view that the Second Law of thermodynamics must be fulfilled. The only approach that ensures the fulfillment of the Second Law of thermodynamics is the molecular theory based on the discrete−continuous lattice gas model. Expressions for the rates of the elementary stage on its basis give a self-consistent description of the equilibrium states of the mixtures under consideration. The common usage today of ideal kinetic models in SC processes in modeling industrial chemistry contradicts the non-ideal equation of states. The used molecular theory is the theory of absolute reaction rates for non-ideal reaction systems, which takes into account intermolecular interactions that change the effective activation energies of elementary stages. This allows the theory to describe the rates of elementary stages of chemical transformations and molecular transport at... [more]
An Improved Fault Diagnosis Approach for Pumps Based on Neural Networks with Improved Adaptive Activation Function
Fangfang Zhang, Yebin Li, Dongri Shan, Yuanhong Liu, Fengying Ma
November 30, 2023 (v1)
Keywords: adaptive activation function, deep learning, fault diagnosis, pumping unit
Due to the complex underground environment, pumping machines are prone to producing numerous failures. The indicator diagrams of faults are similar to a certain degree, which produces indistinguishable samples. As the samples increase, manual diagnosis becomes difficult, which decreases the accuracy of fault diagnosis. To accurately and quickly judge the fault type, we propose an improved adaptive activation function and apply it to five types of neural networks. The adaptive activation function improves the negative semi-axis slope of the Rectifying linear unit activation function by combining the gated channel conversion unit to improve the performance of the deep learning model. The proposed adaptive activation function is compared to the traditional activation function through the fault diagnosis data set and the public data set. The results show that the activation function has better nonlinearity and can improve the generalization performance of the deep learning model and the ac... [more]
A Method for Defining Sedimentary Characteristics and Distributions and Its Application in Qinnan Depression, Bohai Bay Basin
Zehua Zhang, Chunqiang Xu, Chenjie Wang, Hong Li, Wensen Zhu, Hongliang Wang, Kaixuan Liang, Yong Su
November 30, 2023 (v1)
Keywords: geological model, paleogeomorphology, Qinnan depression, seismic facies, seismic forward modeling, stratigraphic pattern
A new method incorporating geophysical analysis and geological analysis is proposed to define the sedimentary characteristics and distributions in basins with few drilling wells to promote the exploration of reservoirs. This method is applied to a study, through which its principles, closed-loop workflow and technologies are introduced in detail and the sedimentary characteristics and distributions of the study area are accurately defined. During the application process of the method, a compatible geological model is established, based on which the seismic data are interpreted and the results derived from the interpretation are further verified via seismic forward modeling. The study results exhibit a successive sand-rich deposition from the retrogradational gully-filling gravity flow deposition including near-shore fans, slope fans and basin-floor fans delimited by different slope break belts in transgressive sequences to the progradational delta deposition in a retrogressive sequence... [more]
Bioavailability, Sources, and Transfer Behavior of Heavy Metals in Soil−Crop Systems from a High Geological Background Area Impacted by Artisanal Zn Smelting in Guizhou Province, Southwest China
Honghong Ma, Chen Zhao, Li Zhang, Zhizhuo Liu, Fugui Zhang, Huiyan Wang, Fei Guo, Shiqi Tang, Zheng Yang, Min Peng
November 30, 2023 (v1)
Subject: Environment
Keywords: bioavailability, farmland soil, heavy metals, soil contamination, soil–plant transfer factor
The environmental risk posed by heavy metals in agricultural soil is primarily influenced by their sources, bioavailability, and geochemical transfer behavior. This study focused on Weining County, a region in Guizhou province, Southwest China, with a high geological background and long-term impact from artisanal Zn smelting. Vertical soil profiles, crop, and rhizospheric soil samples were collected and analyzed for heavy metal concentration (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, and Zn) including the total concentration and chemical fraction. The results revealed elevated concentrations of Cd (range: 0.7−6.9 mg·kg−1), Co (range: 19.3−120.0 mg·kg−1), Cu (range: 71.6−386.0 mg·kg−1), Ni (range: 51.0−121.0 mg·kg−1), and V (range: 310.0−721.0 mg·kg−1) in all soil samples compared to the background values of Guizhou Province. Chemical fractionation analysis indicated that Cr, Ni, As, Cu, and Zn were predominantly present in the residual fraction, while Hg and Pb were predominantly found in the... [more]
Review of Recent Advances in the Drive Method of Hydraulic Control Valve
Yanchao Li, Ruichuan Li, Junru Yang, Xiaodong Yu, Jikang Xu
November 30, 2023 (v1)
Keywords: displacement accuracy, drive performance, hydraulic control valve, response speed, spool drive
Hydraulic control valves are widely used in industrial production, agricultural equipment, construction machinery, and other large power equipment for controlling the pressure and flow of fluids in hydraulic systems. The driving method has a significant impact on the response and control accuracy of hydraulic valves. This paper reviews the driving methods of spools from five aspects: solenoid drive, material expansion drive, motor drive, hydraulic valve drive, and another drive. It summarizes the various schemes currently available for spool drive and analyzes each of them. After optimizing the driving method of the valve core, the control accuracy can reach 3%, and the minimum response time is 7 ms. According to the characteristics of the different drive methods, the differences between them are compared, the advantages and disadvantages of each drive method are analyzed, and the application scenarios for each drive method are identified. Solutions to the drawbacks of the existing dri... [more]
Non-Catalytic and Catalytic Conversion of Fruit Waste to Synthetic Liquid Fuel via Pyrolysis
Eylem Pehlivan
November 30, 2023 (v1)
Keywords: bio-oil, catalytic pyrolysis, clinoptilolite, plum stone, TGA, zeolite
Plum stone stands out as an alternative biomass source in terms of obtaining fuel and chemicals with or without catalysts under different conditions. Under variable heating rates (10, 50, and 100 °C min−1) and pyrolysis temperatures (400, 450, 500, 550, and 600 °C), plum stone was pyrolyzed at a constant rate in a constant sweep gas flow (100 cm3 min−1) in a tubular fixed-bed reactor. According to the results, an oil yield reaching a maximum of 45% was obtained at a heating rate of 100 °C min−1 and pyrolysis temperature of 550 °C in the non-catalytic procedure. The catalytic pyrolysis was carried out with two selected commercial catalysts, namely ZSM-5 and PURMOL-CTX and clinoptilolite (natural zeolite, NZ) under optimum conditions with a catalyst ratio of 10% of the raw material. With the addition of catalyst, the quantity and quality of bio-oil increased, including calorific capacity, the removal of oxygenated groups, and hydrocarbon distribution. In the presence of catalysts, an inc... [more]
Dynamic Characteristics Analysis of Metallurgical Waste Heat Radiative Drying of Thin Layers of Sewage Sludge
Hongyan Guo, Zhiwei Tan, Haiying Li, Yue Long, Aimin Ji, Liangxu Liu
November 30, 2023 (v1)
Keywords: activation energy, dry model, effective diffusion coefficient, metallurgical waste heat, municipal sludge
The utilization of metallurgical waste heat for urban sludge drying and dewatering not only affects the subsequent cost of sludge treatment but also provides a pathway for the rational utilization of metallurgical waste heat. The influence of different experimental conditions on sludge drying characteristics, such as drying temperature and thickness, was analyzed based on metallurgical waste heat. Based on the analysis and evaluation of the drying kinetics parameters of commonly used drying mathematical models, a modified Midilli drying kinetic model is proposed. The kinetic parameters and effective diffusivity of sludge drying were analyzed in three stages of sludge drying: rising rate, constant rate, and falling rate. By utilizing the Arrhenius equation, the relationship between the effective diffusion coefficient and thermodynamic temperature is established, revealing the apparent activation energies for the three stages of urban sludge drying as 29.772 kJ·mol−1, 37.129 kJ·mol−1, an... [more]
Research on the Positioning Accuracy of the Cutting Head of a Tunneling Machine Based on Ultra-Wideband Positioning Technology
Haiyan Ma, Hongkai Zhang, Kunlin Yang, Yingjie Hu, Zeyu Yang, Nianjie Ma
November 30, 2023 (v1)
Keywords: cutting head of roadheader, distance measurement, positioning accuracy, ultra-wideband positioning
Directed at the problems of low positioning accuracy and irregular section forming of cutting heads of road header in coal mine production sites, a new cutting head positioning system based on ultra-wideband positioning technology is proposed based on the cutting head motion model and the working principle of ultra-wideband positioning technology, which verifies the anti-interference and the accuracy of its positioning. Combined with the simulation experiment under on-site working conditions, the influence degree of three typical influencing factors on positioning accuracy was obtained, and the accuracy optimization of the ultra-wideband positioning system was guided. Through the dynamic solution experiment, the positioning accuracy of the system is measured, and the results are verified based on the positioning system solution accuracy evaluation standard.
Homogeneous Field Measurement and Simulation Study of Injector Nozzle Internal Flow and Near-Field Spray
Ping Chen, Rongwu Xu, Zhenming Liu, Jingbin Liu, Xusheng Zhang
November 30, 2023 (v1)
Keywords: Computational Fluid Dynamics, diesel fuel injector, internal flow, near-field spray, X-ray phase contrast imaging
The homogeneous field measurement of internal flow and spray of internal combustion engine injector nozzles under high pressure has always been one of the difficulties in experimental research. In this paper, an actual-size aluminum alloy nozzle is designed, and the simultaneous measurement of internal flow and near-field spray is successfully realized with the help of synchrotron radiation X-ray phase contrast imaging technology under an injection pressure of 30~90 MPa. For a 0.25 mm aperture nozzle, different radii of the inlet corner can induce different cavitation layer thicknesses, and the measured flow section shrinkage ratio is 0.70. The flow characteristics in the nozzle are entirely connected to the jet characteristics, indicating a tight correlation between internal flow and jet morphology. Finally, the internal cavitation of the nozzle was studied by the CFD simulation, and the simulation results are in good agreement with the experiment.
Three-Dimensional Printing of Synthetic Core Plugs as an Alternative to Natural Core Plugs: Experimental and Numerical Study
Juan Antonio Cruz-Maya, José Luis Mendoza-de la Cruz, Luis Carlos Martínez-Mendoza, Florencio Sánchez-Silva, José Alfredo Rosas-Flores, Janet Jan-Roblero
November 30, 2023 (v1)
Subject: Other
Keywords: core flooding test, digital rock physics, three-dimensional (3D) additive manufacturing
This paper proposes three-dimensional (3D) additive fabrication of synthetic core plugs for core flooding experiments from spheres and grains of Berea Sandstone using a digital particle packing approach. Samples were generated by systematically combining the main textural parameters of the rock reservoir to design synthetic core plugs Numerical flow simulation was per-formed using the lattice Boltzmann method (LBM) to verify the flow distribution and permeability for comparison with the experimentally measured permeability and to that obtained from correlations in the literature. The digital porosity of the sample was compared to the porosity measured using an HEP-P helium porosimeter. The numerical and experimental results for permeability and porosity differed by a maximum of 18%.
Innovative Method for Determining Young’s Modulus of Elasticity in Products with Irregular Shapes: Application on Peanuts
Joelle Nader, Jean Claude Assaf, Espérance Debs, Nicolas Louka
November 30, 2023 (v1)
Keywords: Hooke’s theory, peanuts, response surface methodology, stress-strain, Young’s modulus of elasticity
Accurate determination of Young’s modulus of elasticity in irregularly shaped products is quite challenging. This study introduces a novel method that can measure the elasticity in non-uniform products, such as peanuts. Variations of the contact surface between the peanut and a crosshead were precisely calculated using this technique based on kernels blueprints remaining on graph paper after compression. The elastic modulus was assessed by stress-strain tests using Hooke’s theory. The significance of the effects of water content and loading rate on the elastic modulus of peanuts was studied using the Response Surface Methodology (RSM). Results showed that the elasticity was mostly influenced by the kernel’s water content. It decreased from 3.75 to 0.10 MPa when the initial water content increased from 7 to 18% (dry basis). Water content had a significant effect on Young’s modulus (p < 0.05) at 95% confidence level with a correlation coefficient (R2) of 95.52%. Conversely, the effect... [more]
The Law of Gas−Liquid Shear Mixing under the Synergistic Effect of Jet Stirring
Wei Zhou, Hui Wang, Lingling Wang, Liang Li, Chuanchuan Cai, Jinbo Zhu
November 30, 2023 (v1)
Subject: Materials
Keywords: interaction impact, multiphase mixing, synergy
At present, there is a common problem that the mixing mode is single and it is difficult to overcome the inherent bottleneck of multiphase mixing. A mixing device combining the advantages of jet entrainment and mixing dispersion was designed and built. In an effort to determine the mixing degree of two phases, the mixing coefficient of gas−liquid charging was measured using the cylinder method with the optimal working parameters. To explore the optimization of the mixing conditions and control mechanism of multiphase materials, the law of gas−liquid shear mixing in the process of multi-force field synergistic change was revealed. Based on the testing of the gas injection capacity under different working conditions and the calculation of the gas−liquid two-phase mixing coefficient, it was concluded that the flow rate was the direct key factor affecting the gas injection capacity. The working speed also had a certain impact on the gas injection capacity. When working at a high speed and... [more]
Molecular Insight into the Occurrence Characteristics of Deep Oil with Associated Gas Methane and the Displacement Resistance in Water Flooding in Nano-Pore Throat
Lixia Zhou, Weiming Wang, Youguo Yan, Chengen Zhao, Jiahao Zhong, Yuqi Liu
November 30, 2023 (v1)
Keywords: molecular dynamic simulation, oil with associated gas, the occurrence characteristics, water displacement oil and gas process
In deep oil reservoirs, the existence of associated gas generally has a crucial impact on crude oil properties and flow performance. In this work, adopting molecular dynamic simulation, we studied the occurrence characteristics of oil with associate gas methane (the molar ratio of methane to oil rm/o were 1/4, 2/3, 3/2, and 4/1) in nano-pore throat and the displacement behavior of oil and methane in the water flooding process. Simulation results indicated: (1) an increasing replacement of the adsorption-status oil by methane as the methane content increased; (2) the oil and methane displacement efficiency was enhanced as the methane content increased in the water displacement oil and gas process; (3) the threshold displacement pressure gradually decreases as the methane content increases. The microscopic characteristics of the occurrence features and displacement performance of crude oil with associated methane in nano-pore throat were discussed in detail, and the underlying mechanism... [more]
Effect of LiCl Electrolyte Concentration on Energy Storage of Supercapacitor with Multilayered Ti3C2Tx MXene Electrodes Synthesized by Hydrothermal Etching
Alexey Tsyganov, Alexander Shindrov, Maria Vikulova, Denis Zheleznov, Alexander Gorokhovsky, Nikolay Gorshkov
November 30, 2023 (v1)
Keywords: capacity, Energy Storage, hydrothermal etching, molten salt, MXene, supercapacitor
The development of new electrode materials for electrochemical systems for various purposes is a significant and in-demand task of scientific research. Layered transition metal carbides and nitrides, known as MXenes, show great potential for use as electrodes in electrochemical energy storage devices operating in aqueous electrolytes. In this work, a multilayer Ti3C2Tx MXene was obtained from a Ti3AlC2 precursor and studied as the electrode material of a symmetrical supercapacitor with an aqueous LiCl electrolyte. The formation of the MXene structure was confirmed by the data from X-ray phase analysis and scanning electron microscopy. The X-ray diffraction pattern showed the disappearance of the main reflections related to the Ti3AlC2 phase and the shift of the reflection peak (002) from 9.4° to 6.7°, which indicated successful etching of the Al layers from the Ti3AlC2 precursor. At electrolyte concentrations of 1, 5, 10, and 20 M, the supercapacitors demonstrated high specific capacit... [more]
The Displacement Behaviors of Different Pore-Scales during CO2 Flooding and Huff-n-Puff Processes in Tight Oil Reservoirs Using Nuclear Magnetic Resonance (NMR)
Mingyang Yang, Shijun Huang, Kuiqian Ma, Fenglan Zhao, Haoyue Sun, Xinyang Chen
November 30, 2023 (v1)
Keywords: Carbon Dioxide, EOR, NMR, pore-scales, tight oil reservoir
Injecting CO2 into tight oil reservoirs is a potential approach for enhanced oil recovery (EOR) and CO2 sequestration. However, the effects of different pore-scales on EOR are poorly understood, and this has a significant impact on recovery. In this paper, a pore size correction model based on X-ray computerized tomography (CT) and nuclear magnetic resonance (NMR) was developed in order to establish the relationship between the pore radius and the transverse relaxation time. Different pore-scales are divided according to the cumulative distribution characteristics of the transverse relaxation time (T2). CO2 flooding and huff-n-puff experiments were conducted to investigate the dynamic displacement behaviors in different pore-scales. The results indicate that there are three pore-scales: micropores (T2 < 0.3 ms), intermediate pores (0.3 ms < T2 < 100 ms), and macropores (100 ms < T2). However, there are also pseudo-sweep pores (PPs), equilibrium pores (EPs), and sweep pores... [more]
Multi-Objective Optimization of a Novel Ribbed Honeycomb Heat Sink for an Electro-Hydrostatic Actuator
Yanpeng Li, Huijun Han, Mingzhong Li, Jinhu Zhang, Youwang Xing, Sheng Lei, Xiang Yu
November 30, 2023 (v1)
Subject: Optimization
Keywords: electro-hydrostatic actuator, heat sink, multi-objective particle swarm optimization
The electro-hydrostatic actuator (EHA) is a new type of power-by-wire (PBW) actuation system, which is utilized to realize a more electric aircraft. However, EHA suffers from serious thermal problems, due to its high integration and high power density. Therefore, a reasonable heat dissipation structure is an essential method for solving this problem. In this paper, a novel ribbed honeycomb heat sink (RHCS) developed by combining a ribbed heat sink (RHS) with a honeycomb heat sink (HCS) is proposed. Moreover, the optimization of heat sink parameters was achieved by using a multi-objective particle swarm optimization algorithm (MOPSO). Initially, the thermal resistance and mass models of the HCS were constructed, based on which the optimal structural parameters of the honeycomb cell were obtained. In addition, the thermal resistance model of RHCS was constructed using the response surface method, and parameters such as rib spacing, height and width were obtained based on MOPSO. Finally,... [more]
Energy Variation Features during the Isothermal Adsorption of Coal under High-Temperature and High-Pressure Conditions
Tongling Jing, Chuanqi Tao, Yanbin Wang, Huan Miao, Mingyu Xi, Xingchen Zhao, Haiyang Fu
November 30, 2023 (v1)
Keywords: high-temperature and high-pressure, isothermal adsorption, methane adsorption, surface free energy
This paper aims to describe methane adsorption in coal under the conditions of high temperature and high pressure, as well as quantitatively decipher the change rule of energy in the isothermal adsorption process. The isothermal adsorption test was carried out with four groups of middle-rank coals from the Linxing area with different degrees of metamorphism. The impacts of the degree of deterioration of coal, temperature, and pressure on adsorption were analyzed with regard to the adsorption amount, adsorption potential, and adsorption space. Additionally, the energy change during the adsorption of methane by the coal was considered. The results show that the coal adsorption capacity hinges on the degree of deterioration of the coal, as well as the pressure and temperature. Additionally, the impact of temperature upon coal methane adsorption under depth conditions is highlighted. Like the adsorption space, the adsorption potential is an important parameter used to quantitatively charac... [more]
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