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The Analysis and Rapid Non-Destructive Evaluation of Yongchuan Xiuya Quality Based on NIRS Combined with Machine Learning Methods
Ying Zang, Jie Wang, Xiuhong Wu, Rui Chang, Yi Wang, Hongyu Luo, Yingfu Zhong, Quan Wu, Zhengming Chen, Min Deng
February 19, 2024 (v1)
Subject: Materials
Keywords: artificial neural network, near infrared spectroscopy, principal component analysis, quality evaluation, Yongchuan Xiuya
This paper attempts to analyze and assess Yongchuan Xiuya tea quality quickly, accurately, and digitally. The sensory evaluation method was first used to assess Yongchuan Xiuya tea quality, and then near infrared spectroscopy (NIRS) was obtained, and standard methods were applied to the testing of the chemical components. Next, principal component analysis (PCA) and the correlation coefficient method were used to comprehensively screen out the representative components. Finally, NIRS combined with partial least squares regression (PLSR) and back propagation artificial neural network (BP-ANN) methods were applied to build quality evaluation models for Yongchuan Xiuya tea, respectively, and external samples were employed to examine the practical application results of the best model. The cumulative variance contribution rate of the first three principal components of the ingredients in tea was 97.73%. Seven components closely related to tea quality were screened out, namely, amino acids,... [more]
Experimental Study on Methane Diffusion Characteristics of Different Metamorphic Deformed Coals Based on the Counter Diffusion Method
Jiangang Ren, Liang Gao, Zhihui Wen, Hongbo Weng, Jianbao Liu, Runsheng Lv, Yanwei Qu, Zhimin Song, Yongwang Zhang, Bing Li
February 19, 2024 (v1)
Keywords: confining pressure, counter diffusion method, diffusion coefficient, gas pressure, temperature
The diffusion coefficient (D) is a key parameter that characterizes the gas transport occurring in coal seams. Typically, D is calculated using the desorption curve of particle coal. However, this method cannot accurately reflect the diffusion characteristics under the stress constraint conditions of in situ coal seams. In this study, different metamorphic deformed coals of medium and high coal rank were considered based on Fick’s law of counter diffusion. The change laws of D under different confining pressures, gas pressures, and temperature conditions were tested and analyzed, and the influencing mechanisms on D are discussed. The results showed that D of different metamorphic deformed coals exponentially decreased with an increase in confining pressures, and exponentially increased with increases in gas pressures and temperature. There is a limit diffusion coefficient. The influence of the confining pressure on D can essentially be determined by changes in the effective stress, and... [more]
Selection and Optimization Design of PDC Bits Based on FEM Analysis for Drilling Long Horizontal Sections of Shale Formations
Lulin Kong, Zhaowei Wang, Haige Wang, Mingyue Cui, Chong Liang, Xiangwen Kong, Ping Wang
February 19, 2024 (v1)
Keywords: bit selection, Duvernay area, FEM modeling, long horizontal section, optimization design of PDC bits, shale gas
Well structures with ultra-long sections have become one of the most applied technologies in the field of shale gas development. While there have been many technical challenges, enhancing the breaking efficiency and stability of polycrystalline diamond compact (PDC) bits has become an essential issue of focus. Since 2013, the well structure in the Duvernay area has been optimized multiple times, and the rate of penetration (ROP) of the entire wellbore has nearly doubled. However, there are significant differences in terms of the performances of different PDC bits, and there is still room for improvement to optimize these drill bits. For this reason, a confined compressive strength test was conducted to obtain the rock mechanical parameters from shale cores extracted from the long horizontal section. Using these data, a finite element model (FEM) was developed with a corresponding scale. A calibration of the elastic-plastic damage constitutive models was then performed using the FEM. Th... [more]
Machine Learning Aided Prediction of Glass-Forming Ability of Metallic Glass
Chengcheng Liu, Xuandong Wang, Weidong Cai, Yazhou He, Hang Su
February 19, 2024 (v1)
Keywords: glass-forming ability, Machine Learning, metallic glass, optimal design
The prediction of the glass-forming ability (GFA) of metallic glasses (MGs) can accelerate the efficiency of their development. In this paper, a dataset was constructed using experimental data collected from the literature and books, and a machine learning-based predictive model was established to predict the GFA. Firstly, a classification model based on the size of the critical diameter (Dmax) was established to determine whether an alloy system could form a glass state, with an accuracy rating of 0.98. Then, regression models were established to predict the crystallization temperature (Tx), glass transition temperature (Tg), and liquidus temperature (Tl) of MGs. The R2 of the prediction model obtained in the test set was greater than 0.89, which showed that the model had good prediction accuracy. The key features used by the regression models were analyzed using variance, correlation, embedding, recursive, and exhaustive methods to select the most important features. Furthermore, to... [more]
Study on the Influence of the Joint Angle between Blast Holes on Explosion Crack Propagation and Stress Variation
Xiangyang Wang, Xiantang Zhang, Jingshuang Zhang, Hongmin Zhou, Peng Zhang, Dan Li
February 19, 2024 (v1)
Keywords: crack propagation, effective stress, joint angle, numerical simulation, stress wave
The joints and fissures in a natural rock mass can affect the mechanical properties of the rock mass, the propagation of a blasting stress wave, and the blasting effect of the smooth surface of roadways. In the process of roadway drilling and blasting, there will inevitably be some joints between the two blast holes. Taking the joint angle as the starting point, this paper studies the rule of rock explosion crack propagation and stress variation when there are joints with different angles between two blast holes and analyzes the influence of joints on rock mechanical properties and blasting effects. The numerical simulation method and the software ANSYS/LS-DYNA are used to establish 7 rock mass models with various joint angles. When there is no joint between two holes and joints of 15°, 30°, 45°, 60°, 75°, and 90°, the propagation of explosive cracks and stress variations in the rock mass are discussed. The results show that the joints at different angles have obvious guiding and block... [more]
Special Issue on “Secondary Metabolites: Extraction, Optimization, Identification and Applications in Food, Nutraceutical, and Pharmaceutical Industries”
Ibrahim M. Abu-Reidah
February 19, 2024 (v1)
Subject: Biosystems
There is a growing interest in utilizing natural plant extracts in the food and beverage industries [...]
Enhancing the Photocatalytic Performance of BiVO4 for Micropollutant Degradation by Fe and Ag Photomodification
Marin Popović, Tayebeh Sharifi, Marijana Kraljić Roković, Boštjan Genorio, Boštjan Žener, Igor Peternel, Urška Lavrenčič Štangar, Hrvoje Kušić, Ana Lončarić Božić, Marin Kovačić
February 19, 2024 (v1)
Subject: Environment
Keywords: BiVO4, ciprofloxacin, design of experiments, iron, isotype homojunction, modification, photomodification, silver, vacancy
Wider application of BiVO4 (BVO) for photocatalytic water treatment is primarily limited by its modest photocatalytic effectiveness, despite its appropriately narrow band gap for low-cost, sunlight-facilitated water treatment processes. In this study, we have photomodified an isotype BVO, consisting of a tetragonal zircon and monoclinic scheelite phase, with Fe (Fe@BVO) and Ag (Ag@BVO) ionic precursors under UV illumination in an aqueous ethanol solution in order to assess their effect on the opto-electronic properties and effectiveness for the removal of ciprofloxacin (CIP). Fe@BVO failed to demonstrate enhanced effectiveness over pristine BVO, whereas all Ag@BVO achieved improved CIP degradation, especially 1% Ag@BVO. At pH 4 and 6, 1% Ag@BVO demonstrated nearly 24% greater removal of CIP than BVO alone. Photomodification with Fe created surface oxygen vacancies, as confirmed by XPS and Mott−Schottky analysis, which facilitated improved electron mobility, although no distinct Fe-cont... [more]
Semantic Hybrid Signal Temporal Logic Learning-Based Data-Driven Anomaly Detection in the Textile Process
Xu Huo, Kuangrong Hao
February 19, 2024 (v1)
Keywords: anomaly detection, temporal logic, textile process, time-series data
The development of sensor networks allows for easier time series data acquisition in industrial production. Due to the redundancy and rapidity of industrial time series data, accurate anomaly detection is a complex and important problem for the efficient production of the textile process. This paper proposed a semantic inference method for anomaly detection by constructing the formal specifications of anomaly data, which can effectively detect exceptions in process industrial operations. Furthermore, our method provides a semantic interpretation of exception data. Hybrid signal temporal logic (HSTL) was proposed to improve the insufficient expressive ability of signal temporal logic (STL) systems. The epistemic formal specifications of fault offline were determined, and a data-driven semantic anomaly detector (SeAD) was constructed, which can be used for online anomaly detection, helping people understand the causes and effects of anomalies. Our proposed method was applied to time-seri... [more]
Special Issue: Synthesis, Application, and Biological Evaluation of Chemical Organic Compounds
Stanimir Manolov, Iliyan Ivanov
February 19, 2024 (v1)
Subject: Materials
This Special Issue of Processes, entitled “Synthesis, Application, and Biological Evaluation of Chemical Organic Compounds”, gathers the most recent work of leading researchers in a single forum [...]
Microseismic Monitoring of the Fracture Nucleation Mechanism and Early Warning for Cavern Rock Masses
Jin-Shuai Zhao, Yue-Mao Zhao, Peng-Xiang Li, Chong-Feng Chen, Jian-Cong Zhang, Jiang-Hao Chen
February 19, 2024 (v1)
Keywords: early warning, fracture nucleation, microseismic monitoring, stability analysis, underground cavern
The rock mass is susceptible to instability and damage during cavern construction. The blast-induced cracking process of the rock mass contains a wealth of information about the precursors of instability, and the identification of fracture nucleation signals is a prerequisite for effective hazard warning. A laboratory mechanical test and microseismic (MS) monitoring were carried out in the Baihetan Cavern to investigate the fracture nucleation process in the rock mass. MS monitoring shows that pre-existing microcracks were closed or new cracks were generated under the action of high stress, which caused the migration of microcracks. As the crack density increases, the fracture interaction gradually increases. The study of the rock fracture nucleation mechanism helps to reveal the MS sequences during the rock fracture process, and the fore-main shock was found in the MS sequence during access tunnel excavation. This study can effectively provide guidance for the early warning of rock ma... [more]
Temporary Plugging Agent Evaluation Technology and Its Applications in Shale Reservoirs in the Sichuan Basin
Liang Wang, Jian Yang, Junliang Peng, Huifen Han, Yang Wang, Zefei Lv
February 19, 2024 (v1)
Subject: Other
Keywords: particle-size optimization, shale oil, Sichuan Basin, temporary blocking and turning in fracturing, temporary plugging agent
Shale oil reservoirs in the Daanzhai section of central Sichuan are mainly developed in the Daer subsection, with a rich resource base and great exploration and development potential. However, the shale oil reservoir is characterized by shale and limestone interactions, poor physical properties, undeveloped fractures, and large differences in the fracture pressure of interactive reservoirs. Therefore, it is necessary to use temporary plugging and diverting fracturing technology to improve the complexity of fractures in reservoir reconstruction. To this end, an experimental device was innovatively established that takes into account the morphology of fractures and the permeability of reservoirs, and it can evaluate the temporary blocks and turns within third-level fractures in a reservoir. It can simulate third-level turning fractures under conditions involving 3−15 mm crack openings and different roughness values. Using this device and method, the combination and particle-size optimiza... [more]
Improving the Energy Efficiency of the Production of Pipes Welded with High-Frequency Induction
Zbigniew Techmański, Jacek Stępień, Tomasz Garstka, Paweł Wieczorek, Grzegorz Golański, Jan Supernak
February 19, 2024 (v1)
Keywords: electric power, heat-affected zone, high-frequency induction, inductor, squeeze
This article presents the technical aspects that may reduce electric power consumption during the welding of pipes with the high-frequency induction (HFI) method. Experiments were carried out at Huta Łabędy S.A. Steelworks, during the test production of 323.9 × 5.6 mm pipes of P235GH steel grade. Two sets of HFI heating system settings were studied: with a variable squeeze force of the heated edges and a variable position of the inductor in relation to the welding point. It was proven that the temperature at the welding point increased due to the stronger squeeze of the heated edges, which reduced the electric power consumption. Reducing the distance of the inductor relative to the welding point had the same effect. By optimizing the squeeze force and the position of the inductor, energy consumption was reduced by about 5.5%. Microstructural studies of the welds did not show any adverse effects of the optimization.
Systematic Evaluation of Research Progress in the Textile Field over the Past 10 Years: Bibliometric Study on Smart Textiles and Clothing
Ting Wang, Changqing Liu, Jun Zhang, Aosi Wang
February 19, 2024 (v1)
Subject: Materials
Keywords: bibliometrics, CiteSpace, intellectual structure, knowledge mapping, smart fibers, smart textiles and clothing
Intelligent textile clothing is one of the most popular topics in the field. In recent decades, rapid advances have been made in the area of intelligent textile clothing research, and the intellectual structure pertaining to this domain has significantly evolved. We used CiteSpace 6.2.R4, VOSviewer 1.6.19, to evaluate and visualize the results, analyzing articles, countries, regions, institutions, authors, journals, citations, and keywords. Both a macroscopic sketch and a microscopic characterization of the entire knowledge domain were realized. The aim of this paper is to utilize bibliometric and knowledge mapping theories to identify relevant research papers on the subject of smart textiles and clothing that have been published by the China Knowledge Network Web of Science (WOS) within the last decade. It is concluded that the main topics of smart textile and garment research can be divided into nine categories: wearable electronics, smart textiles, flexible antennas, energy storage,... [more]
Advances in Triboelectric Nanogenerators for Sustainable and Renewable Energy: Working Mechanism, Tribo-Surface Structure, Energy Storage-Collection System, and Applications
Van-Long Trinh, Chen-Kuei Chung
February 19, 2024 (v1)
Keywords: energy applications, energy collecting system, Energy Storage, renewable and sustainable, triboelectric nanogenerator
Triboelectric nanogenerators (TENGs) are emerging as a form of sustainable and renewable technology for harvesting wasted mechanical energy in nature, such as motion, waves, wind, and vibrations. TENG devices generate electricity through the cyclic working principle of contact and separation of tribo-material couples. This technology is used in outstanding applications in energy generation, human care, medicinal, biomedical, and industrial applications. TENG devices can be applied in many practical applications, such as portable power, self-powered sensors, electronics, and electric consumption devices. With TENG energy technologies, significant energy issues can be reduced or even solved in the near future, such as reducing gas emissions, increasing environmental protection, and improving human health. The performance of TENGs can be enhanced by utilizing materials with a significant contrast in their triboelectrical characteristics or by implementing advanced structural designs. This... [more]
Performance Improvement Overview of the Supercritical Carbon Dioxide Brayton Cycle
Xurong Wang, Longwei Zhang, Zhenhua Zhu, Mingjiang Hu, Jing Wang, Xiaowei Fan
February 19, 2024 (v1)
Keywords: binary mixture, combined cycle, performance improvement, review, supercritical carbon dioxide cycle
Efficiency and compactness are core strengths of the supercritical carbon dioxide (sCO2) Brayton cycle, which is considered an alternative to the steam Rankine cycle for moderate-temperature heat sources (350−800 °C). Numerical investigations on system design and analysis have received considerable attention, with the aim of improving the sCO2 cycle from the viewpoint of thermodynamics. This paper reviews and compares previous studies in the literature to survey different cycle layouts, operating parameters, and working fluids of the sCO2 cycle. Performance enhancement approaches are categorized into three classes according to characteristics: conventional methods, CO2 mixtures, and combined cycles. The strengths, weaknesses, and limitations of each categorized method are discussed. This research is expected to provide a roadmap for performance improvement that meets the interests of researchers.
A Full-State Reliability Analysis Method for Remanufactured Machine Tools Based on Meta Action and a Markov Chain Using an Exercise Machine (EM) as an Example
Yueping Luo, Yongmao Xiao
February 19, 2024 (v1)
Keywords: EM, full state, MA unit (MAU), Markov chain, reliability analysis, RMT
The reliability of an RMT can be regarded as an important indicator customers can use to recognize its quality; however, it is difficult to implement a full-state reliability analysis of an RMT due to its complicated structural functions. Therefore, a full-state reliability analysis model is proposed herein based on meta action (MA) and a Markov chain for remanufactured exercise machine tools (REMTs). First, an analysis was carried out on individual levels by integrating the MAU decomposition method, and an MAU fault tree model was established layer by layer for the REMT. Second, full-state modeling was performed in view of the MAU characteristics of the REMT, whose operation processes are divided into MAU normal and failure states. A Markov decision-making process was introduced to integrate MAU states and establish our model, which was solved by means of an analytical method for the evaluation of reliability. Finally, an example of a remanufactured machine tool spindle is given to ve... [more]
New Alternatives in the Fight against Tuberculosis: Possible Targets for Resistant Mycobacteria
Eduardo Rodríguez-Bustamante, Saúl Gómez-Manzo, Alvaro De Obeso Fernández del Valle, Roberto Arreguín-Espinosa, Clara Espitia-Pinzón, Eden Rodríguez-Flores
February 19, 2024 (v1)
Subject: Biosystems
Keywords: diarylquinolines, drug resistant TB strains, Mycobacterium tuberculosis, natural products, novel vaccine generation, repurposing drugs, treatment
Tuberculosis (TB) is a bacterial disease that remains a global health threat due to the millions of deaths attributed to it each year. The emergence of drug resistance has exacerbated and further increased the challenges in the fight against this illness. Despite the preventive measures using the application of the Bacillus Calmette-Guérin vaccine, the desired immunization outcome is not as high as expected. Conventional TB treatments exhibit serious limitations, such as adverse effects and prolonged duration, leading to a pressing need for alternative and more effective treatment options. Despite significant efforts, it took nearly four decades for diarylquinoline to become the most recently approved medicine for this disease. In addition, various possibilities, such as the usage of medications used for many other conditions (repurposed drugs), have been explored in order to speed up the process of achieving faster outcomes. Natural compounds derived from various sources (microorganis... [more]
Antimicrobial Resistance of Heterotrophic Bacteria and Enterobacteriaceae Inhabiting an Anthropogenic-Affected River Stretch in Bulgaria
Zvezdimira Tsvetanova, Hristo Najdenski
February 19, 2024 (v1)
Subject: Biosystems
Keywords: antibiotics, antimicrobial resistance, E. coli, Enterobacteriaceae, heterotrophic bacteria, surface water, waste water
The increasing antimicrobial resistance (AMR) of pathogens is a significant threat to human and animal health, but it is also an environmental challenge for water resources. The present study aimed to quantify heterotrophic bacteria resistant to five groups of antibiotics (ABs) in a selected Yantra River stretch (including its tributary, the Belitsa River); to assess AMR prevalence among Enterobacteriaceae; and to assess the impact of urban effluents or rural runoff on AMR prevalence along the river course at eight sampling points. Culture-dependent methods were used in a population-based study of total AMR and for AB susceptibility testing of Enterobacteriaceae isolates. The data reveal significant differences in AMR dissemination and a lower (up to 10%) proportion of different types of antibiotic-resistant bacteria (ARB) in the Yantra River water compared to the Belitsa River (up to 20%). The incidence of resistant Enterobacteriaceae isolates was in the range of 1% to gentamicin to 3... [more]
Reservoir Space Characterization of Ordovician Wulalike Formation in Northwestern Ordos Basin, China
Yuman Wang, Shangwen Zhou, Feng Liang, Zhengliang Huang, Weiling Li, Wei Yan, Wei Guo
February 19, 2024 (v1)
Subject: Materials
Keywords: foreland basin, fracture, Ordos Basin, Ordovician, reservoir characterization, reservoir space, siliceous shale, Wulalike Formation
The Ordovician Wulalike Formation in the northwestern Ordos Basin is a new prospect for exploring marine shale gas in China, facing prominent problems such as unclear reservoir conditions and the distribution of enrichment areas. The types of reservoir space, fracture development, porosity composition, and physical properties of the lower Wulalike Formation are discussed through the multi-method identification and quantitative evaluation of reservoir space for appraisal wells. The Wulalike Formation in the study area contained fractured shale reservoirs with matrix pores (mainly inorganic pores) and permeable fractures. The fracture system of the lower Wulalike Formation is dominated by open bed-parallel fractures that are intermittent or continuous individually, with a width of 0.1−0.2 mm and spacing of 0.5−14.0 cm. The fracture-developed intervals generally exhibit bimodal or multimodal features on NMR T2 spectra and have a dual-track feature with a positive amplitude difference in d... [more]
Computational Fluid Dynamics Simulation of Combustion and Selective Non-Catalytic Reduction in a 750 t/d Waste Incinerator
Hai Cao, Yan Jin, Xiangnan Song, Ziming Wang, Baoxuan Liu, Yuxin Wu
February 10, 2024 (v1)
Keywords: gas-solid two-phase combustion coupling, grate furnace, numerical simulation, SNCR
In this study, a Computational Fluid Dynamics (CFD) approach using Ansys Fluent 15.0 and FLIC software was employed to simulate the combustion process of a 750 t/d grate-type waste incinerator. The objective was to assess the performance of Selective Non-Catalytic Reduction (SNCR) technology in reducing nitrogen oxide (NOx) emissions. Two-stage simulations were conducted, predicting waste combustion on the bed and volatile matter combustion in the furnace. The results effectively depicted the temperature and gas concentration distributions on the bed surface, along with the temperature, velocity, and composition distributions in the furnace. Comparison with field data validated the numerical model. The findings serve as a reference for optimizing large-scale incinerator operation and parameter design through CFD simulation.
Study on Performance Optimization of Water-Rich Grouting Materials Based on Response Surface Methodology
Xiaoping Li, Guoping Han, Yong Wang, Jie Xu, Jie Du, Bo Yang, Min Zhang, Tao Li, Bo Li
February 10, 2024 (v1)
Subject: Materials
Keywords: gas extraction, orthogonal experiment methodology, response surface methodology, scanning electron microscope, water-rich grouting materials
The quality of borehole sealing is a key factor affecting the efficiency of gas production. A new water-rich grouting material (RW) with composite coagulant and other additives was prepared in this study to overcome the disadvantages of long setting time and low stone rate of traditional cement materials. When the coagulants A is 4 g and coagulants B is 2 g, the setting time of RW material was reduced by 60.85% and 50.62%, which significantly shortened the setting time of the RW material, respectively. Based on the orthogonal method, 29 groups of comparative experiments were designed to investigate the interaction mechanism between different additives on the performance index of RW, including setting time, water secretion rate, and compressive strength. Quadratic regression equations were fitted using the response surface method. All the correlation coefficients R2 of each response model were greater than 0.97, R2 and R2adj were less than 0.2 through variance analysis, indicating a hig... [more]
Research Regarding the Dimensional Precision of Electrical Steel Strips Machined by Waterjet Cutting in Multilayer Packages
Daniel Nasulea, Alexandru Catalin Filip, Silvia Zisu, Gheorghe Oancea
February 10, 2024 (v1)
Keywords: dimensional accuracy, electrical motor, electrical steel strip, multilayer package, waterjet machining
Manufacturing parts made of thin steel in small batches is a challenging task in terms of reaching the proper balance between the productivity, the cost, and the dimensional precision. This paper presents the results of experimental research about manufacturing electrical steel thin parts using abrasive waterjet cutting. For a certain increase of productivity and a more efficient process, the parts were cut using multilayer packages of steel strips. The main objective was to analyze the influence of the number of layers on the dimensional precision of parts. Preliminary tests were performed, followed by a full factorial experiment using two independent parameters, the number of layers and the traverse speed. The parts were measured on a noncontact vision measurement machine and mathematical models were determined to predict the parts deviations depending on the independent parameters used. A practical validation of the models was performed. The main conclusion is that the number of lay... [more]
Low-Carbon Economic Dispatch of Electricity and Cooling Energy System
Yubo Wang, Ling Hao, Libin Zheng, Lei Chen, Fei Xu, Qun Chen, Yong Min
February 10, 2024 (v1)
Subject: Optimization
Keywords: building thermal inertia, carbon trading mechanism, elastic thermal comfort, electric-cooling dispatch, pipeline thermal characteristics
In response to the issue of the hydropower consumption of run-of-river hydropower stations in Southwest China, the district cooling system can provide regulation capacity for hydropower utilization and suppress fluctuations caused by the uncertainty of hydropower. The innovative method is to utilize the thermal characteristics of pipelines and buildings, as well as the thermal comfort elasticity to shift the cooling and electricity loads, which helps to consume the surplus hydroelectric power generation. Taking the minimum total cost of coal consumption in thermal power units, hydropower abandonment penalty, and the carbon trading cost as the objective function, models were established for power supply balance constraints, heat transport constraints, and unit output constraints. The hybrid integer linear programming algorithm was used to achieve the low-carbon economic dispatch of the electric-cooling system. The calculation examples indicate that compared to the traditional real-time... [more]
Integral Effects of Porosity, Permeability, and Wettability on Oil−Water Displacement in Low-Permeability Sandstone Reservoirs—Insights from X-ray CT-Monitored Core Flooding Experiments
Zhongnan Wang, Keyu Liu, Chaoqian Zhang, Haijun Yan, Jing Yu, Biao Yu, Jianliang Liu, Tailiang Jiang, Weidong Dan, Caizhi Hu
February 10, 2024 (v1)
Subject: Materials
Keywords: low-permeability reservoir, permeability, porosity, waterflooding, wettability, X-ray CT
Porosity, permeability, and wettability are crucial factors that affect the oil−water displacement process in reservoirs. Under subsurface conditions, the integral effects of these factors are extremely difficult to document. In this paper, waterflooding experiments were carried out using a core flooding system monitored with X-ray dual-energy CT. The mesoscale, three-dimensional characteristics of water displacing oil were obtained in real time. The integral effects of porosity, permeability, and wettability on the waterflooding in the low-permeability sandstone reservoirs were investigated. It was found that if the reservoir rock is water-wet, then the residual oil saturation decreases gradually with increasing porosity and permeability, showing an increasing waterflooding efficiency. On the contrary, if the reservoir rock is oil-wet, the residual oil saturation gradually increases with improving porosity and permeability, showing a decreasing waterflooding efficiency. The porosity,... [more]
Improved Time-Varying BLF-Based Tracking Control of a Position-Constrained Robot
Tan Zhang, Jinzhong Zhang
February 10, 2024 (v1)
Keywords: adaptive control, barrier Lyapunov function, constraint control, robot, tracking control
In this work, one improved symmetric time-variant logarithmic barrier, Lyapunov function (BLF), is developed for the first time to handle the state constraint problem of nonlinear systems. It is universal in the sense that the improved barrier function is a general one that can be used not only in systems with constrained requirements but also in systems without constrained requirements, without altering the designed controller. First of all, the n-link robotic system is transformed into a kind of multi-input and multi-output (MIMO) system. Then, a trajectory tracking control scheme is designed by combining the improved time-variant logarithmic BLF with the disturbance observer to solve the problems of model uncertainty and position constraint for the robotic system. We give that under the proposed controller, all the robotic system’s error vectors can trend to the equilibrium point asymptotically while the constraint conditions on the position are always met. Finally, the effectivenes... [more]
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