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Records added in 2023
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Showing records 51 to 75 of 36338. [First] Page: 1 2 3 4 5 6 7 Last
Anti-Inflammatory and Antinociceptive Activity of Herbal Lipospheres of Pentaclethra macrophylla (Fabaceae) Stem Bark Extract
Petra Obioma Nnamani, Edith Obioma Diovu, Ikechukwu Emmanuel Peter, Akachukwu Marytheresa Onwuka, Chiamaka Victory Ogbuanwu, Obiora Emmanuel Abonyi, Brigitta Loretz, Claus-Michael Lehr
November 30, 2023 (v1)
Subject: Materials
Keywords: anti-inflammatory activity, antinociception, herbal liposphere, Pentaclethramacrophylla, solidified reverse micellar solutions (SRMS), stem bark extract
Purpose: Inflammation of various degrees is common among humans. There are associated side effects with orthodox delivery systems and anti-inflammatory agents; hence, the study investigated the characteristics of herbal lipospheres and the anti-inflammatory potency of the lipospheres formulated from Pentaclethra macrophylla with the view to having a drug with a better delivery system and lesser side effects. Methods: Herbal lipospheres were formulated using solidified reverse micellar solutions (SRMS) of P90H and goat fat and characterized for particle size and morphology, pH time dependent analysis, encapsulation efficiency (EE%), and Fourier Transform infrared spectroscopy. The in vitro antinociceptive and anti-inflammatory studies were carried out using membrane stabilization by hypotonicity-induced hemolysis and the determination of anti-platelet aggregatory activity models. The in vivo antinociceptive and anti-inflammatory studies on egg albumin- and formaldehyde-induced arthritis... [more]
Investigating the Mechanism of Continuous−Discrete Coupled Destabilization of Roadway-Surrounding Rocks in Weakly Cemented Strata under Varying Levels of Moisture Content
Lihui Sun, Zhixin Jiang, Yaxin Long, Qingfeng He, Haiyang Zhang
November 30, 2023 (v1)
Keywords: anchorage failure mechanism, continuous–discrete, destabilization mechanism, moisture content, weakly cemented rock
This study examines frequent disasters, including large-scale deformation and collapse, caused by underground mining in weakly cemented strata in Western China. The weakly cemented rock’s unique characteristics, including low strength and easy disintegration, demonstrate a different damage pattern than that traditionally seen in the central and eastern regions. Using Fast Lagrangian Analysis of Continua-Particle Flow Code (FLAC2D-PFC2D) coupling, we model the strata, focusing on the 3-1 coal seam roadway at Hongqinghe mine. This study investigates the damage−rupture−destabilization progression in the peripheral rock under varying levels of moisture content. Our findings indicate that a water content of ω = 5.5% is the threshold for roadway damage, and moisture content 5.5% abruptly increases cracks and shifts the rock’s force chain, causing significant deformation and affecting the ceiling the most. Moreover, higher levels of moisture content weaken the anchor solid’s performance, with... [more]
Discrete-Element-Method-Based Determination of Particle-Level Inputs for the Continuum Theory of Flows with Moderately Cohesive Particles
Kevin M. Kellogg, Peiyuan Liu, Christine M. Hrenya
November 30, 2023 (v1)
Keywords: cohesion, continuum theory, discrete element method, particle flows
In this work, the cohesion-specific inputs for a recent continuum theory for cohesive particles are estimated for moderately cohesive particles that form larger agglomerates via discrete element method (DEM) simulations of an oscillating shear flow. In prior work, these inputs (critical velocities of agglomeration and breakage and collision cylinder diameters) were determined for lightly cohesive particles via the DEM of simple shear flow—i.e., a system dominated by singlets and doublets. Here, the DEM is again used to extract the continuum theory inputs, as experimental measurements are infeasible (i.e., collisions between particles of a diameter of <100 μm). However, simulations of simple shear flow are no longer feasible since the rate of agglomeration grows uncontrollably at higher cohesion levels. Instead, oscillating shear flow DEM simulations are used here to circumvent this issue, allowing for the continuum theory inputs of larger agglomerate sizes to be determined efficient... [more]
Numerical Analysis of Viscous Polymer Resin Mixing Processes in High-Speed Blade-Free Planetary Blender Using Smoothed Particle Hydrodynamics
Kwon Joong Son
November 30, 2023 (v1)
Keywords: mixing processes, mixing simulation, planetary mixer, smoothed particle hydrodynamics, viscous fluid blending
High-speed planetary mixers can rapidly and efficiently combine rheological liquids, such as polymer resins and paste materials, because of the large centrifugal forces generated by the planetary motion of the mixing vessel. Only a few attempts have been made to computationally model and analyze the intricate mixing patterns of highly viscous substances. This paper presents meshless flow simulations of the planetary mixing of polymeric fluids. This research utilized the smoothed particle hydrodynamics (SPH) approach for numerical calculations. This method has advantages over the finite-volume method, which is a grid-based computational technique, when it comes to modeling interfacial and free surface flow problems. Newtonian rheology and interfacial surface force models were used to calculate the dissipative forces in the partial differential momentum equation of fluid motion. Simulations of the flow of an uncured polyurethane resin were carried out while it was mixed in a planetary mi... [more]
Structural Design and Preparation Process Research of Stacked MEMS Gas Sensors for Volatile Organic Compound Gases
Guizhou Wu, Junfeng Wu, Juan Dong, Xinyu Zhang
November 30, 2023 (v1)
Keywords: gas sensitivity characteristics, MEMS gas sensor, porphyrin zinc, volatile organic compounds
To design gas sensors with fast response speed and high sensitivity for the detection of volatile organic compounds, a stacked MEMS sensor was designed in this study. It utilizes porphyrin-sensitive materials and carbon nanotubes to form composite materials, improve the thermal stability of sensitive materials, and conduct sensor gas sensitivity testing. The results show that the design of the thermal insulation structure makes the sensor obtain lower power consumption and more uniform temperature distribution, and the maximum deformation variable is 3.7 × 10−2 μM. Doping carbon nanotubes in porphyrin-sensitive materials can effectively improve their thermal stability, and the sensor is in a safe state at temperatures below 358 °C. The sensor with higher response recovery characteristics at a low concentration of 80 ppm aniline has better response recovery characteristics, with a response time of 33 s and a recovery time of 23 s, respectively; its response recovery characteristics to 1... [more]
Numerical Simulation and Experiment on Pill Coating of Red Clover Seeds under the Action of Vibrating Force Field
Mengjun Guo, Xuyang Cai, Xuejie Ma, Zhanfeng Hou, Xin Tong, Haiyang Liu
November 30, 2023 (v1)
Keywords: EDEM, red clover seeds, rotational speed, seed coating, vibration
In order to solve the problem of the low qualification rate of the pilling and coating of small-grain forage seeds, a vibration force field is introduced to the traditional vertical disk coating machine to promote the mixing of materials and improve the qualification rate of the pilling. Using the typical small-grain forage seed red clover as an example, we used the vibration force field after adding seed powder particles to a coating pot for the theoretical analysis of the force situation, using the discrete element software EDEM to construct a red clover seed simulation model with the coefficient of discretization as the evaluation index. We studied the effects of the rotational speed of the coating pot, the vibration frequency of the pot, the amplitude of the vibration of the pot, and the other operating parameters of the pot on the uniformity of the seed powder mixing, with the pelletization of the pass rate as the physical evaluation standard, using a one-way test to study the eff... [more]
Decentralized Control Strategy for Participation of Electric Vehicles in Distribution Voltage Control
Xin Fang, Juan Li, Yubo Yuan, Xiaodong Yuan
November 30, 2023 (v1)
Keywords: decentralized voltage control, electric vehicle, electric vehicle charging station, rolling optimization
With the accelerating transportation electrification, increasing numbers of electric vehicles (EVs) are connected to distribution networks via electric vehicle charging stations (EVCSs). Due to the uncertain charging behaviors of EV users, concentrated high-power EV charging during peak hours can result in significant undervoltage issues, affecting the regular operation of distribution networks and having detrimental effects on regular EV charging. Conventional EV charging scheduling methods are conducted in a centralized way, requiring extensive investment in communication infrastructure and intensive computing power. Accordingly, this paper proposes a novel decentralized voltage control scheme with the participation of EVs and EVCSs. The proposed control scheme first divides the distribution network into clusters based on a modified modularity index. Then, it applies the rolling optimization-based control of the EVs and EVCSs within each cluster to solve the regional voltage problems... [more]
An Amended Crow Search Algorithm for Hybrid Active Power Filter Design
Shoyab Ali, Annapurna Bhargava, Akash Saxena, Abdulaziz S. Almazyad, Karam M. Sallam, Ali Wagdy Mohamed
November 30, 2023 (v1)
Subject: Optimization
Keywords: crow search algorithm, design, filter, numerical optimization, power quality, swarm intelligence
Hybrid Active Power Filter (HAPF) imbibes the advantages of both passive and active power filters. These filters are considered one of the important technologies for mitigating harmonic pollution in electrical systems. Accurate estimation of filter parameters is a key component to reduce harmonic pollution effectively. In recent years, several optimization approaches have been reported to solve this estimation problem; still, this area is worthy of further investigation. This paper is a proposal for an estimator that can estimate the parameter of HAPF configuration accurately. For evolving this estimator, first, an objective function that mathematically embeds filter parameters and harmonic pollution is presented. For handling the optimization process, an Amended Crow Search Algorithm (ACSA) is proposed. ACSA employs a local search algorithm (in the form of a pattern search) for obtaining optimal results. The analysis of the estimation process is carried out on two HAPF configurations.... [more]
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.
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