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Showing records 3146 to 3170 of 43292. [First] Page: 1 123 124 125 126 127 128 129 130 131 Last
Isolation, Genomic, and Proteomic Characterization of a Novel Neotropical Strain of Bacillus thuringiensis with Mosquitocidal Activities
Giselly Batista Alves, Marcelo Leite Dias, Eugenio Eduardo de Oliveira, Gil Rodrigues dos Santos, Bergmann Morais Ribeiro, Raimundo Wagner de Souza Aguiar.
June 7, 2023 (v1)
Subject: Biosystems
Keywords: Bacillus thuringiensis, biorational mosquito control, genome sequencing, pesticidal proteins, proteomic.
The combination of genomic and proteomic analyses is a useful tool for the study of novel Bacillus thuringiensis (Bt) strains, as these approaches allow the accurate identification of pesticidal proteins and virulence factors produced. Here, we isolated and evaluated the potential of a novel Neotropical Bt strain (TOD651) for controlling larvae of Aedes aegypti and Culex quinquefasciatus mosquitoes. Aiming for the full comprehension of the TOD651 larvicidal potential, we further evaluated the whole TOD651 genome and conducted the proteomic analysis of the TOD651 spore−crystal mixtures. Our results showed that Bt TOD651 similarly killed both A. aegypti (0.011 µg/mL) and C. quinquefasciatus (0.023 µg/mL) larvae, exhibiting similar potency to the commercial Bt strain. The genome sequence revealed that Bt TOD651 harbors cry11Aa3, cry10Aa4, cry4Aa4, cry4Ba5, cyt1Aa5, cyt1Ca1, cyt2Ba13, mpp60Aa3, and mpp60Ba3. The proteomic analysis revealed no expression of Mpp60Aa3, while all the other pes... [more]
Prediction in Catalytic Cracking Process Based on Swarm Intelligence Algorithm Optimization of LSTM
Juan Hong, Wende Tian.
June 7, 2023 (v1)
Subject: Optimization
Keywords: catalytic cracking process, cuckoo search, long short-term memory network, Particle Swarm Optimization, prediction.
Deep learning can realize the approximation of complex functions by learning deep nonlinear network structures, characterizing the distributed representation of input data, and demonstrating the powerful ability to learn the essential features of data sets from a small number of sample sets. A long short-term memory network (LSTM) is a deep learning neural network often used in research, which can effectively extract the dependency relationship between time series data. The LSTM model has many problems such as excessive reliance on empirical settings for network parameters, as well as low model accuracy and weak generalization ability caused by human parameter settings. Optimizing LSTM through swarm intelligence algorithms (SIA-LSTM) can effectively solve these problems. Group behavior has complex behavioral patterns, which makes swarm intelligence algorithms exhibit strong information exchange capabilities. The particle swarm optimization algorithm (PSO) and cuckoo search (CS) algorit... [more]
Study on Failure Mechanism of Roadway Surrounding Rock and Hierarchical Continuous Support Technology in Unidirectional Fault Area
Zhengzheng Xie, Fengchun Mu, Feng Guo, Nong Zhang, Yongle Li, Ruiji Chen, Qinghua Chen.
June 7, 2023 (v1)
Keywords: bolt-grouting support, fault, hierarchical continuous support, roadway, transboundary.
A fault is a common geological structure in coal mining. Large deformation or even instability and collapse often occur in roadways in fault areas, which restricts the safe and efficient production of mines. With the track roadway of the 5206 working face of Xin’an Coal Mine as the engineering background, this study aims to explore the failure mechanism of surrounding rock under the influence of fault structures. Field investigation and numerical simulation were used comprehensively to analyze the failure characteristics of the surrounding rock under the influence of a unidirectional fault structure. Based on the principle of thick-layer transboundary anchorage, the hierarchical continuous support technology of transboundary anchoring in the fault structure area was proposed. The results show that the stress near the fault area is relatively concentrated, and the rock mass strength is low, which may easily cause the deformation and failure of the surrounding rock under the dynamic stre... [more]
Nonisothermal Crystallization Kinetics by DSC: Practical Overview
Sergey Vyazovkin, Nicolas Sbirrazzuoli.
June 7, 2023 (v1)
Keywords: calorimetry, crystallization, glass, kinetics, melt, nonisothermal.
Providing a minimum of theory, this review focuses on practical aspects of analyzing the kinetics of nonisothermal crystallization as measured with differential scanning calorimetry (DSC). It is noted that kinetic analysis is dominated by approaches based on the Avrami and Arrhenius equations. Crystallization kinetics should not be considered synonymous with the Avrami model, whose nonisothermal applications are subject to very restrictive assumptions. The Arrhenius equation can serve only as a narrow temperature range approximation of the actual bell-shaped temperature dependence of the crystallization rate. Tests of the applicability of both equations are discussed. Most traditional kinetic methods tend to offer very unsophisticated treatments, limited only to either glass or melt crystallization. Differential or flexible integral isoconversional methods are applicable to both glass and melt crystallization because they can accurately approximate the temperature dependence of the cry... [more]
Framework for the Implementation of Smart Manufacturing Systems: A Case in Point
Muhammad Hammad, Md Shamimul Islam, Mohammad Asif Salam, Ali Turab Jafry, Inayat Ali, Wasim Ahmed Khan.
June 7, 2023 (v1)
Keywords: framework, fuzzy DEMATEL, sensitivity analysis, significant attributes, smart manufacturing.
Smart manufacturing has become a vital technique for increasing productivity and efficiency. Firms are following a smart manufacturing implementation system to compete in the market. Therefore, it is mandatory to find the crucial factors that enable the implementation of intelligent manufacturing in enterprises. This study proposes the framework for a new model factory based on the three-dimensional model that extends the product lifecycle layer. It also analyzes the significant attributes and interdependence relationships of causes and effects through the fuzzy DEMATEL approach for the selected small and medium enterprises discussed as a case study. The results show that the factors in Region 1 are significant attributes that need to be focused on for the development and establishment of small and medium enterprises under consideration. These attributes include design documentation (A11), intelligently management of small and medium enterprises (A3), visualization and monitoring of lo... [more]
Predicting Octane Number of Petroleum-Derived Gasoline Fuels from MIR Spectra, GC-MS, and Routine Test Data
Alirio Benavides, Carlos Zapata, Pedro Benjumea, Camilo A. Franco, Farid B. Cortés, Marco A. Ruiz.
June 7, 2023 (v1)
Keywords: API gravity, Gasoline, GC-MS, MIR, octane number.
Petroleum-derived gasoline is still the most widely used liquid automotive fuel for ground vehicles equipped with spark-ignition engines. One of the most important properties of gasoline fuels is their antiknock performance, which is experimentally evaluated via the octane number (ON). It is widely accepted that the standard methods for ON measuring (RON: research octane number and MON: motor octane number) are very expensive due to the costs of the experimental facilities and are generally not suitable for field monitoring or online analysis. To overcome these intrinsic problems, it is convenient that the ON of gasoline fuels is estimated via faster methods than the experimental tests and allows for acceptable results with acceptable reproducibility. Various ON prediction methods have been proposed in the literature. These methods differ in the type of fuels for which they are developed, the input features, and the analytical method used to underlie the link between input features and... [more]
Experimental and Numerical Investigations on the Effect of MWCNT-COOH and Al2O3 Hybrid Nanofillers Dispersed CFRP Laminates Subjected to Projectile Impact
Pritam Ghosh, K. Ramajeyathilagam.
June 7, 2023 (v1)
Keywords: alumina, ballistic limit, CFRP, composite damage, delamination, MWCNT-COOH.
Although carbon fiber-reinforced polymer (CFRP) composites have excellent intrinsic mechanical properties, they are vulnerable to impact loads because of their weak inter-laminar fracture toughness, which results in delamination damage. This study presents a novel hybrid nanofiller combination of multi-walled carbon nanotubes (MWCNT) and alumina nanoparticles (Al2O3) to determine improvements in the impact resistance of CFRP laminate. The projectile impact experimental study is carried out on 140 mm × 140 mm × 1.5 mm CFRP laminate with spherical and conical nose shape projectiles. The numerical study of the test plate consisting of six layers is performed, in which each layer is modeled using a shell element and connected through tiebreak contact. Using the Cowper−Symonds equation to determine the dynamic mechanical properties, the numerical validation is established considering the strain rate effect. The results, such as residual velocity, damage area, ballistic limit velocity and de... [more]
Design and Development of Photocatalytic Systems for Reduction of CO2 into Valuable Chemicals and Fuels
Amra Bratovčić, Vesna Tomašić.
June 7, 2023 (v1)
Keywords: efficiency, methane, Methanol, MOFs, photocatalytic CO2 reduction, selectivity, semiconductor, TiO2, Z-scheme heterojunction.
This review presents the results of research in the field of photocatalytic reduction of carbon dioxide (CO2) to methane and methanol as valuable chemicals and fuels. CO2 reduction is a promising technology, but it is an endothermic process with unfavourable thermodynamics. Other limitations include the inertness of the CO2 molecule, the slow multielectron process, and the lack of understanding of the reaction mechanism, leading to low selectivity and insufficient efficiency. Tailoring reaction parameters such as CO2 adsorption, choice of reducing agent, development of photocatalysts in terms of composition, structural properties and morphology, energy band gap, and the presence of surface functional groups can affect the reaction mechanism and selectivity for the desired product. Therefore, the main challenges in this research area are the development of an active and selective catalyst for the photoreduction of CO2 to useful products with high added value and the optimization and dev... [more]
Hybrid Cooling-Based Thermal Management of Containerised Vanadium Flow Battery Systems in Photovoltaic Applications
Bing Shu, Maria Skyllas-Kazacos, Jie Bao, Ke Meng.
June 7, 2023 (v1)
Keywords: photovoltaic applications, temperature dynamics, thermal management.
The integration of industrial batteries with photovoltaic applications is a common practice to charge the batteries using solar energy. Long-duration flow batteries are useful in dealing with the intermittency of renewable energy sources and offer a great opportunity for total fossil fuel replacement. In this study, the effects of different battery operation time and load profiles on the temperature dynamics of a containerised vanadium flow battery system are modelled and simulated for a range of locations and seasons to identify active cooling or heating requirements that might be needed to maintain safe operating temperatures. This paper explores and analyses the stack, tank, and container temperature dynamics of 6 h and 8 h containerised vanadium flow batteries (VFBs) during periods of higher charge and discharge current using computer simulations that apply insulation with passive or active hybrid cooling thermal management where needed to keep the battery temperature within a safe... [more]
Adsorption Behavior and Adsorption Dynamics of Micrometer-Sized Polymer Microspheres on the Surface of Quartz Sand
Jun Li, Taotao Luo, Wende Yan, Tingting Cheng, Keyang Cheng, Lu Yu, Jiannan Cao, Zhongquan Yang.
June 7, 2023 (v1)
Subject: Environment
Keywords: adsorption kinetic model, adsorption pattern, isothermal adsorption thermodynamic equilibrium model, polymer microspheres, static adsorption.
The adsorption of polymer microspheres in a stratum can directly affect its action mode and performance in the actual application process. Understanding the adsorption pattern of polymer microspheres and their adsorption mechanism can facilitate optimization of the application mode and enhance the use efficiency. Ultraviolet spectrophotometry was employed to measure the static adsorption characteristics of polymer microspheres (PMS) on the surface of quartz sand. The PMS adsorption capacity on the surface of quartz sand increased with increasing concentration. When the concentration was 1000 mg/L, the static equilibrium adsorption capacity was 402 μg/g, and monolayer adsorption was dominant. The effect of the contact time on the adsorption was investigated, and the fitting was performed using the isothermal adsorption thermodynamic equilibrium model and the adsorption kinetic model. The adsorption of 800 mg/L PMS tended to equilibrate after 0.8 h of adsorption on the surface of quartz... [more]
Biosynthesis of Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) from Different 4-Hydroxybutyrate Precursors by New Wild-Type Strain Cupriavidus necator IBP/SFU-1
Natalia O. Zhila, Kristina Yu. Sapozhnikova, Evgeniy G. Kiselev, Ekaterina I. Shishatskaya, Tatiana G. Volova.
June 7, 2023 (v1)
Subject: Biosystems
Keywords: 1,4-butanediol, 1,6-hexanediol, 4-hydroxybutyrate, Cupriavidus necator IBP/SFU-1, polyhydroxyalkanoates, properties, ε-caprolactone.
The study addresses the growth of the new wild-type strain Cupriavidus necator IBP/SFU-1 and the synthesis of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB) on media containing fructose and three different precursors of 4HB (ε-caprolactone 1,4-butanediol and 1,6-hexanediol). It was found that ε-caprolactone is the best precursor for the synthesis of P(3HB-co-4HB) copolymers. By varying the concentration and number of doses of ε-caprolactone added into the bacterial culture, it was possible to find conditions that ensured the synthesis of P(3HB-co-4HB) copolymers with different contents of 4HB (from 3−5 to 22.4 mol.%). The physicochemical properties of the copolymers were investigated depending on the proportions of 4HB monomers. The effect of 4HB monomers was manifested in a certain decrease in the weight-average molecular weight (Mw) (272−353 kDa), number-average molecular weight (Mn) (47−67 kDa) of the samples, and an increase in polydispersity (5.09−6.71) compared with... [more]
Pore Structure and Fractal Characteristics of Marine−Continental Transitional Black Shales: A Case Study of the Permian Shanxi Formation in the Eastern Margin of the Ordos Basin
Daxing Wang, Zhitao Xie, Haiyan Hu, Tao Wang, Ze Deng.
June 7, 2023 (v1)
Subject: Materials
Keywords: fractal characteristics, marine–continental transitional shale, micropore structure, Ordos Basin, Shanxi Formation.
To study the microscopic pore characteristics of marine−continental transitional shale, we studied the Daning−Jixian block of the Shanxi Formation using low-pressure CO2 adsorption (LP-CO2A) and low-temperature N2 adsorption (LT-N2A) methods in conjunction with field emission scanning electron microscopy (FE-SEM), geochemistry, and mineral composition analysis in order to obtain pore structure characteristic parameters. The fractal dimension of the pores was calculated using the Frankel−Halsey−Hill (FHH) model, and the study also discusses the factors that influence the pore structure. The study found that the marine−continental transitional phase shale of the Shanxi Formation has clay mineral contents ranging from 36.24% to 65.21%. The total organic carbon (TOC) contents range from 0.64% to 9.70%. Additionally, the organic matter maturity is high. The FE-SEM and gas adsorption experiments revealed that the transitional shale of the Shanxi Formation possesses a diverse range of pore ty... [more]
OCI-OLSR: An Optimized Control Interval-Optimized Link State Routing-Based Efficient Routing Mechanism for Ad-Hoc Networks
Jaspreet Singh, Gurpreet Singh, Deepali Gupta, Ghulam Muhammad, Ali Nauman.
June 7, 2023 (v1)
Keywords: Enhanced OLSR Routing Protocol, MANETs, Network Infrastructure, OLSR Routing, Optimized Control Interval OLSR.
MANET (Mobile Ad hoc Networks) functionality is determined by routing protocols’ ability to adjust to atypical changes in information and communication technologies, topological systems, and connection status. Due to interference, node migration, the growth of several pathways, security, and propagation loss, MANET network configurations are dynamic. The proactive routing protocol enhances the message flow utilized in the neighborhood discovery process by using the multipoint relays (MPR) approach. In order to increase the protocol’s effectiveness and efficiency while maintaining the OLSR protocol’s reliability, the research presented in this paper proposed an improved OCI-OLSR (Optimized Control Interval-Optimized Link State Routing) that focuses on better control interval management, an advanced MPR selection process, reducing neighbor hold time as well as decreasing flooding. The suggested proposed protocol was examined using the NS3 simulator, and it was compared to the standard OL... [more]
Enhancement of LVRT Ability of DFIG Wind Turbine by an Improved Protection Scheme with a Modified Advanced Nonlinear Control Loop
Azeddine Loulijat, Hamid Chojaa, Mouncef El marghichi, Naoufl Ettalabi, Abdelilah Hilali, Abderrahman Mouradi, Almoataz Y. Abdelaziz, Zakaria M. Salem Elbarbary, Mahmoud A. Mossa.
June 7, 2023 (v1)
Keywords: advanced backstepping with integral action control, crowbar, doubly-fed induction generator, improved protection scheme, network disturbance, network voltage dip.
One of the problems with the doubly-fed induction generator (DFIG) is its high vulnerability to network perturbations, notably voltage dips, because of its stator windings being coupled directly to the network. As the DFIG’s stator and rotor are electromagnetically mated, the stator current peak occurs during a voltage dip causing an inrush current to the critical converter back-to-back and an overload of the DC-link capacitor. For this purpose, a series of researchers have achieved a linear and non-linear controller with a crowbar-based protection scheme. With this type of protection, the Rotor Side Converter (RSC) is disconnected momentarily, and consequently, its control of both the active and reactive output power of the stator is totally lost, leading to incorrect power quality at the point of common coupling (PCC). In this document, a robust nonlinear controller by Advanced Backstepping with Integral Action Control (ABIAC) is initially employed to monitor the rotor and the networ... [more]
Optimization Strategy of the Electric Vehicle Power Battery Based on the Convex Optimization Algorithm
Xuanxuan Wang, Wujun Ji, Yun Gao.
June 7, 2023 (v1)
Keywords: convex optimization algorithm, electric vehicle, energy management strategy, motor model, power battery.
With the development of the electric vehicle industry, electric vehicles have provided more choices for people. However, the performance of electric vehicles needs improvement, which makes most consumers take a wait-and-see attitude. Therefore, finding a method that can effectively improve the performance of electric vehicles is of great significance. To improve the current performance of electric vehicles, a convex optimization algorithm is proposed to optimize the motor model and power battery parameters of electric vehicles, improving the overall performance of electric vehicles. The performance of the proposed convex optimization algorithm, dual loop DP optimization algorithm, and nonlinear optimization algorithm is compared. The results show that the hydrogen consumption of electric vehicles optimized by the convex optimization algorithm is 95.364 g. This consumption is lower than 98.165 g of the DCDP optimization algorithm and 105.236 g of the nonlinear optimization algorithm bef... [more]
Experimental Study on Boiling Vaporization of Liquid Hydrogen in Nonspreading Pool
Zhenhua Xie, Shenyin Yang, Shuangshuang Zhao, Xing Liu, Mingshu Bi, Jingjie Ren.
June 7, 2023 (v1)
Keywords: accidental release, boiling correlation, film boiling, liquid hydrogen, perfect thermal contact.
Research on the boiling vaporization process of liquid hydrogen spilled on solid ground is very important for the safety risk assessment of liquid hydrogen. Since the main source of the heat flux in the vaporization process comes from the ground, the heat flux from the ground into the liquid pool should be studied in-depth. In this paper, the boiling vaporization process of liquid hydrogen on the surface of concrete is studied. The analysis of the boiling process of a liquid pool is conducted by utilizing the boiling curve and historical temperature data collected in close proximity to the surface of the concrete. It was found that the boiling regime of a liquid hydrogen pool on the concrete surface presents non-uniformity, and the film boiling of liquid hydrogen on the concrete surface ended earlier than the results calculated by boiling regime correlations. When the measured temperature in the experiment indicates a transition from film boiling to the transition boiling, the temperat... [more]
Effect of Crude Oil and Nitrogen Gas Flow Rates on the Time Taken for Flow Initiation of Waxy Crude Oil
Haizatul Hafizah Hussain, Shaharin Anwar Sulaiman, Girma Tadesse Chala, Hazlina Husin.
June 7, 2023 (v1)
Keywords: flow initiation, nitrogen gas, wax deposition, waxy crude flow loop.
Transportation of waxy crude oil in a production pipeline often encountered flow assurance issues, such as wax deposition. In a case where pipeline shutdown is needed, wax deposit is likely to form within the pipelines, which leads to operational complexity during the restart phase. Commonly, crude oil restarts to flow after a significantly high restart pressure is pumped longer than is necessary. This is due to the physical hindrance caused by the solid wax, which requires additional pressure to disintegrate it before achieving a steady crude oil flow. This study aims to investigate the effect of crude oil and nitrogen gas flow rates on the time taken for crude oil flow initiation using a flow loop rig, which is connected to a nitrogen gas injection system. The nitrogen gas was injected into the test section pipeline at predetermined flow rates within specified periods. After 45 min of static cooling, the crude oil gear pump is switched on to build sufficient pressure to initiate the... [more]
Analysis of Factors of Single-Use Plastic Avoidance Behavior for Environmental Sustainability in China
Feng Gu, Zhaowei Zhu, Sharafat Ali.
June 7, 2023 (v1)
Subject: Energy Policy
Keywords: behavioral control, behavioral intention, climate change and governance, decision-making processes, plastic avoidance behavior, policy intervention, structural equation modeling, subjective norms.
Governments have been introducing strategies to reduce plastic waste. The reduction in plastic waste can be possible through single-use plastic avoidance. However, this is only possible with the proper understanding of the behavioral factors of single-use plastic avoidance behavior (SPAB). This study explores the factors that influence the decision-making process regarding SPAB in China, a major environmental problem, climate change, and global warming. The authors used a questionnaire survey to collect data from 421 respondents and analyze it using structural equation modeling (SEM). The study examines the effects of attitude, subjective norms (SNs), perceived behavior control (PBC), and policy intervention (PI) on single-use plastic avoidance behavior (SPAB) mediated by plastic avoidance behavioral intentions (PABI) and plastic-related environmental concerns (PREC). The analysis reveals that attitude, PBC, and PI significantly affect PABI, which affects SPAB. Moreover, PREC influence... [more]
Review of Two-Dimensional MXenes (Ti3C2Tx) Materials in Photocatalytic Applications
Haidong Yu, Haibing Jiang, Shuji Zhang, Xin Feng, Song Yin, Wenzhi Zhao.
June 7, 2023 (v1)
Subject: Materials
Keywords: cocatalyst, MXenes material, photocatalysis, preparation method.
MXenes (Ti3C2Tx) have gotten a lot of interest since their discovery in 2011 because of their distinctive two-dimensional layered structure, high conductivity, and rich surface functional groups. According to the findings, MXenes (Ti3C2Tx) may block photogenerated electron-hole recombination in the photocatalytic system and offer many activation reaction sites, enhancing the photocatalytic performance and demonstrating tremendous promise in the field of photocatalysis. This review discusses current Ti3C2Tx-based photocatalyst preparation techniques, such as ultrasonic mixing, electrostatic self-assembly, hydrothermal preparation, and calcination techniques. We also summarised the advancements in photocatalytic CO2 reduction, photocatalytic nitrogen fixation, photocatalytic hydrogen evolution, and Ti3C2Tx-based photocatalysts in photocatalytic degradation of pollutants. Lastly, the challenges and prospects of Ti3C2Tx in photocatalysis are discussed based on the practical application of... [more]
Dissipative Particle Dynamics Simulation and Microscopic Experimental Study of Emulsification Performance of Surfactant/Polymer Flooding
Biao Zhang, Baoshan Guan, Weidong Liu, Baoliang Peng, Sunan Cong.
June 7, 2023 (v1)
Keywords: dissipative particle dynamics, emulsification, interfacial tension, microscopic experimental, solubility parameter.
Polymers can increase the viscosity of water, reduce the relative permeability of the water phase, and enhance the flowability of the oil phase; surfactants can form molecular films at the oil−water interface boundaries, thereby reducing interfacial tension. Surfactant/polymer (S/P) flooding technology for enhancing oil recovery has become a major way to increase crude oil production. This study used dissipative particle dynamics (DPD) technology to simulate the emulsification process of a four-component composite system consisting of oil, water, sodium dodecylbenzene sulfonate (SDBS), and partially hydrolyzed polyacrylamide (HPAM). By changing the concentration of the S/P system, the effect on emulsification behavior was analyzed. Combined with particle distribution diagrams and interfacial tension parameters, the effect of the emulsification behavior on the performance of the S/P binary system was analyzed. On this basis, the effect of different emulsion performances on the recovery... [more]
HPLC-UV Analysis of Chrysophanol in Senna occidentalis Extract Obtained by Using the RSM-Optimized Ultrasonic Extraction Process
Gadah A. Al-Hamoud, Perwez Alam, Omer I. Fantoukh, Mohammed F. Hawwal, Ali Akhtar.
June 7, 2023 (v1)
Keywords: Box–Behnken design (BBD), Caesalpiniaceae, chrysophanol, HPLC-UV, response surface methodology (RSM), S. occidentalis.
In this experiment, chrysophanol analysis in Senna occidentalis (aerial parts) extract obtained by optimizing ultrasound-assisted extraction (UAE) variables (temperature, time, and liquid-to-solid ratio) using response surface methodology (RSM) was performed by employing the HPLC-UV method. For UAE process optimization, a highly significant quadratic model (p < 0.001) was projected to attain maximum chrysophanol yield. The extraction temperature, time, and liquid-to-solid ratio for the best UAE method were determined to be 49.3 °C, 57.7 min, and 18.7 mL/g, respectively. The optimized extract was subjected to a chrysophanol analysis utilizing HPLC-UV (fitted with a Pinnacle C18 column), and a gradient mobile phase composed of 0.5% formic acid (solvent A), acetonitrile (solvent B), methanol (solvent C), at a flow rate of 1.0 mL/min, and an optimum wavelength of 279 nm, respectively. It furnished a compact and intense peak of chrysophanol at Rt = 23.809 min. The experimental value (20.... [more]
Research on a Three-Dimensional Fuzzy Active Disturbance Rejection Controller for the Mechanical Arm of an Iron Roughneck
Kaige Zhang, Yanjun Liu, Hua Jia, Feng Yan, Gang Xue.
June 7, 2023 (v1)
Keywords: mechanical arm of an iron roughneck (MAIR), position control, proportional-valve-controlled single-extension (PVCSE) hydraulic cylinder, three-dimensional fuzzy active disturbance rejection controller (TF-ADRC), trajectory planning.
In the position control of the mechanical arm of an iron roughneck (MAIR), a controller with high responsiveness, high accuracy, and high anti-interference capability is necessary. An MAIR consists of two proportional-valve-controlled single-extension (PVCSE) hydraulic cylinders, and a traditional proportional−integral−derivative (PID) controller cannot easily achieve the accuracy and robustness requirements of the hydraulic cylinders. In this paper, a three-dimensional fuzzy active disturbance rejection controller (TF-ADRC) is proposed for an MAIR, which adds a three-dimensional fuzzy module to a classical active disturbance rejection controller (ADRC) to adjust the controller output according to the tracking of differential deviation, deviation change rate, and deviation change acceleration rate. Firstly, the trajectory planning of the MAIR was carried out using the quintic polynomial interpolation method to improve the smoothness of the target trajectory. Then, the reliability of th... [more]
Effects of Coal Permeability Anisotropy on Gas Extraction Performance
Futian Nian, Feng Ju, Chunshan Zheng, Haifei Wu, Xiaoyu Cheng.
June 7, 2023 (v1)
Subject: Other
Keywords: effective extraction area, gas extraction, gas pressure, mining safety, permeability anisotropy.
To investigate gas flow characteristics in coal seams with strong anisotropy, a coupled anisotropic dual-porosity model was established. Effects of permeability anisotropy on variations in gas pressure, gas extraction volume and effective extraction areas were analyzed. Furthermore, mechanisms of crustal stress, initial gas pressure, ultimate adsorption strain and Langmuir volume constant on permeability anisotropy and extraction amount were studied. Results show that permeability anisotropy could result in an elliptical pressure drop zone around production boreholes. Changes in effective gas extraction areas are divided into three stages: slow growth in an elliptical shape, rapid growth with a superposition effect and steady growth in a funnel shape. Permeability isotropy enables faster reaching of stage III than the anisotropy case. As the vertical stress increases, gas pressure distribution around boreholes gradually changes from an ellipse with horizontal direction as long axis to... [more]
Investigating the Influence of Joint Angles on Rock Mechanical Behavior of Rock Mass Using Two-Dimensional and Three-Dimensional Numerical Models
Yang Zhao, Ye Zhao, Zhe Zhang, Wenhai Wang, Jiaming Shu, Yang Chen, Jianguo Ning, Lishuai Jiang.
June 7, 2023 (v1)
Keywords: jointed rock, mechanical behavior, uniaxial compression, uniaxial tension.
Numerical testing is an ideal testing method in the research on the mechanical behaviors of jointed rock. However, there are few systematic studies focused on the comparison between the two-dimensional (2D) and the three-dimensional (3D) simulation effects on rock mechanical behaviors, particularly those of jointed rock. In this paper, a particle flow model was established by utilizing PFC2D and PFC3D to represent the rock materials, and the rock (especially jointed rock) mechanical behaviors (uniaxial compressive strength UCS, tensile strength TS, crack initiation stress level Kσ, and the pattern of crack initiation) between 2D and 3D models were compared and analyzed. As expected, the result shows that the UCS and TS showed an increasing tendency with the increase in the joint angle (β) for both the 2D and the 3D models, and the strength of the 3D model was less than that of the 2D model under uniaxial compression but was greater than that of the 2D model under uniaxial tension. The... [more]
Study on Flow Characteristics of Flue Gas and Steam Co-Injection for Heavy Oil Recovery
Yanmin Ji, Boliang Li, Zongyuan Han, Jian Wang, Zhaomin Li, Binfei Li.
June 7, 2023 (v1)
Keywords: flow characteristic, flue gas, heavy oil, microscopic experiment, steam.
Flue gas is composed of N2 and CO2, and is often used as an auxiliary agent for oil displacement, with good results and very promising development prospects for co-injection with steam to develop heavy oil. Although research on the oil displacement mechanism of flue gas has been carried out for many years, the flow characteristics of steam under the action of flue gas have rarely been discussed. In this paper, the flow resistance and heat transfer effect of flue gas/flue gas + steam were evaluated by using a one-dimensional sandpack, a flue gas-assisted steam flooding experiment was carried out using a specially customized microscopic visualization model, and the microscopic flow characteristics in the process of the co-injection of flue gas and steam were observed and analyzed. The results showed that flue gas could improve the heat transfer effect of steam whilst accelerating the flow of steam in porous media and reducing the flow resistance of steam. Compared with pure steam, when t... [more]
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