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Showing records 1 to 25 of 1034. [First] Page: 1 2 3 4 5 Last
Adsorption of Pesticides on Activated Carbons from Peach Stones
Souha Harabi, Sami Guiza, Ariadna Álvarez-Montero, Almudena Gómez-Avilés, Mohamed Bagané, Carolina Belver, Jorge Bedia
June 21, 2024 (v1)
Subject: Materials
Keywords: 2,4-dichlorophenoxyacetic acid, activated carbon, Adsorption, carbofuran, isotherms, kinetics, pesticides
This study analyzes the adsorption of two model pesticides, namely, 2,4-dichlorophenoxyacetic acid (2,4-D) and carbofuran on activated carbons obtained by chemical activation with phosphoric acid of peach stones. The effect of the synthesis conditions on the surface area development was analyzed. The highest surface area was obtained with an impregnation time of 5 h, an impregnation ratio equal to 3.5, an activation temperature of 400 °C, and 4.5 h of activation time. Under these conditions, the maximum specific surface area was equal to 1182 m2·g−1 which confirms the high porosity of the activated carbon, predominantly in the form of micropores. The surface chemistry of this activated carbon was also characterized using pH at point of zero charge, scanning electron microscopy, and Fourier transform infrared spectroscopy. Both kinetics and equilibrium adsorption tests were performed. Adsorption kinetics confirmed that 2,4-D adsorption follows a pseudo first-order adsorption kinetic mod... [more]
The Contribution of Cornelian Cherry (Cornus mas L.) Alcoholic Beverages on the Sensory, Nutritional and Anti-Nutritional Characteristics—In Vitro and In Silico Approaches
Oskar Szczepaniak, Barbara Stachowiak, Henryk Jeleń, Kinga Stuper-Szablewska, Katarzyna Szambelan, Joanna Kobus-Cisowska
June 21, 2024 (v1)
Keywords: alcoholic beverages, amygdalin, antiradical capacity, Cornus mas, DFT, volatile compounds
Food producers have focused on novel and attractive raw materials with functional properties. Cornelian cherry (Cornus mas L.) fruits contain numerous compounds that may be beneficial for health. Objective: This study aimed to compare and assess the physicochemical properties and amygdalin levels in brandy and liquor prepared from frozen cornelian cherry fruits. Density functional theory-based B3LYP functionals were used to analyze the spectral and optical properties of amygdalin. The contents of the compounds and volatile products of amygdalin decay were found in two spirituose beverages of Cornus mas, using HPLC and GC-MS. Significant differences in their physicochemical properties were detected between the samples. Alcoholic beverages based on cornelian cherry fruits were rich in a wide range of functional ingredients with a low concentration of amygdalin. In silico analysis showed that orbital density diffusion has a major effect on the physical properties of amygdalin, while diffe... [more]
Investigating the Influencing Factors of Imbibition of Fracturing Fluids in Tight Reservoirs
Jian Liu, Xuefeng Qu, Jiwei Wang, Qiang Liu, Lei Zhang, Tao Huang, Haiyang Yu
June 21, 2024 (v1)
Subject: Materials
Keywords: fracturing fluids, matrix permeability, pressure, temperature, tight reservoir
Tight reservoirs are the focus of unconventional oil and gas resource development, but most tight reservoirs exhibit complex pore structures, strong non-homogeneity, and limited water drive development. Fracturing fluid imbibition is a critically important way to improve the recovery of tight reservoirs. In this paper, an NMR experimental device was used to conduct imbibition experiments in tight reservoirs, and the relationship between temperature, pressure, matrix permeability, and imbibition recovery was investigated. Based on the fracturing fluid imbibition recovery curve, the imbibition process is divided into the fast imbibition stage, slow imbibition stage, and imbibition equilibrium. In addition, based on the pore structure division, the recovery changes of each pore under different experimental conditions were quantitatively analyzed. The results indicate that the highest imbibition recovery is achieved at an experimental pressure of 5 MPa within the range of 0 MPa to 15 MPa.... [more]
Study on the Effectiveness of the Integral Emergency Response System for Coal Mine Water Hazard Accidents Based on Combination Weighting
Yu Hao, Huanhuan Yang, Lijun Zhang, Chaolun Sun
June 21, 2024 (v1)
Keywords: coal mine safety, effectiveness measurement, emergency response, water hazard accidents
Improving the emergency response effectiveness of coal mines in response to water hazard accidents not only plays a vital part in minimizing the resultant losses, but also functions as an important index for evaluating the emergency response capability of coal mines. Therefore, it is of great necessity to test the emergency response capability of coal mines. In this study, an effectiveness measurement index system for the emergency response system that comprises two primary indexes (i.e., response capability and service capability) and six secondary indexes (i.e., accident information transmission, emergency command and control, emergency rescue and mitigation, emergency management, personnel team, and prevention and preparation) was constructed. Additionally, a technique for order preference by similarity to ideal solution (TOPSIS) model for evaluating the effectiveness of the integral emergency response system for coal mine water hazard accidents, based on combination weighting, was... [more]
Recent Advances in Reservoir Stimulation and Enhanced Oil Recovery Technology in Unconventional Reservoirs
Lufeng Zhang, Linhua Pan, Yushi Zou, Jie Wang, Minghui Li, Wei Feng
June 21, 2024 (v1)
In the past decade, significant advances in reservoir stimulation and enhanced oil recovery technologies have resulted in rapid production growth in unconventional reservoirs [...]
Leveraging Dion−Jacobson Interface Hierarchies for Defect Alleviation in High-Efficiency and Durable Perovskite Solar Cells
Jianxiao Bian, Yuncong Zhang, Yang Liu, Xiaonan Pan
June 21, 2024 (v1)
Keywords: 2D/3D structure, 4-(Aminomethyl)piperidine, Dion–Jacobson phase, perovskite solar cells, two-dimensional perovskites
The noteworthy stability of Dion−Jacobson (DJ) phase two-dimensional perovskites marks them as potential contenders for use in optoelectronic applications. Nonetheless, their proliferation is considerably stymied by the constrained charge transport properties inherent to them. This bottleneck is adeptly navigated by deploying 2D-DJ perovskite top layers, seamlessly integrated on 3D perovskite films. We unveil a novel organic cation salt, 4-(Aminomethyl)piperidine (4AMP), as a potent facilitator for treating perovskite photovoltaic films. By employing the annealing technique, we facilitated the in situ creation of a hybrid 2D/3D architecture. Contrasted with conventional 3D architectures, the delineated perovskite heterojunctions with a 2D/3D structure exhibit superior enhanced charge separation, and mitigate photovoltaic losses by proficiently passivating intrinsic defects. The size-graded perovskite 2D/3D structure engineered herein significantly elevates the charge transfer performan... [more]
Low Energy Cost Synchronization Strategy for Markovian Switching Complex Systems/Networks: Multiple Perspectives Comparative Analysis
Qian Xie, Haolan Xu, Jian Dang, Zhe Wang
June 21, 2024 (v1)
Keywords: complex systems/networks, event-triggered control strategy, Markovian switching, pinning control strategy
In this paper, the low energy cost synchronization control strategy of Markovian switching complex systems/networks is mainly studied and analyzed through multiple perspectives. Firstly, in order to achieve synchronization of Markovian switching complex networks with low energy cost, a control scheme based on the optimal node selection strategy that does not depend on the network coupling strength is improved, and a finite-time controller with a simpler structure is constructed. Secondly, based on the event-triggered control strategy an effective trigger event is designed to achieve the low energy cost synchronization of Markovian switching complex networks on the basis of reducing the information transmission and interaction between networks. Finally, the two control strategies mentioned in this paper are compared and analyzed from multiple perspectives through numerical simulations to better guide practical engineering.
The Nutritional Value of Plant Drink against Bovine Milk—Analysis of the Total Concentrations and the Bio-Accessible Fraction of Elements in Cow Milk and Plant-Based Beverages
Maja Welna, Anna Szymczycha-Madeja, Anna Lesniewicz, Pawel Pohl
June 21, 2024 (v1)
Keywords: bio-accessibility, cow milk, inductively coupled plasma optical emission spectrometry, multi-element analysis, nutritional value, plant-based drink
Four types of non-dairy (plant) drinks—almond, oat, rice, and soy—as well as cow milk with varying fat contents (1.5%, 2.0%, and 3.2%), were examined and compared in terms of the total concentrations of Al, As, B, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Na, Mn, Ni, P, Pb, Sb, Se, Sr, and Zn using inductively coupled optical emission spectrometry (ICP OES). Additionally, in vitro gastrointestinal digestion was used to determine the bio-accessible fraction of selected elements, evaluating the nutritional value and risk assessment involved with the consumption of these beverages. A significant difference in the mineral profile was observed depending on the type of plant drink, with the highest content of elements noted in the soy drink and the lowest in the rice drink. Except for Ca and P, the soy drink appears to be a much better source of essential nutrients, including Cu, Fe, and Mn, than cow’s milk. A similar Ca content in plant beverages can be obtained only by adding calcium salt at the stag... [more]
In Silico and In Vitro Analyses of Multiple Terpenes Predict Cryptotanshinone as a Potent Inhibitor of the Omicron Variant of SARS-CoV-2
Asmita Shrestha, Siddha Raj Upadhyaya, Bimal K. Raut, Salyan Bhattarai, Khaga Raj Sharma, Niranjan Parajuli, Jae Kyung Sohng, Bishnu P. Regmi
June 21, 2024 (v1)
Subject: Biosystems
Keywords: COVID-19, Omicron variant, spike protein, terpenes
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant (B.1.1.529) underwent a substantial number of alterations, and the accompanying structural mutations in the spike protein prompted questions about the virus’s propensity to evade the antibody neutralization produced by prior infection or vaccination. New mutations in SARS-CoV-2 have raised serious concerns regarding the effectiveness of drugs and vaccines against the virus; thus, identifying and developing potent antiviral medications is crucial to combat viral infections. In the present study, we conducted a detailed in silico investigation that involves molecular docking, density functional (DFT) analysis, molecular dynamics (MD) simulations, and pharmacological analysis followed by an in vitro study with the spike protein. Among fifty terpenes screened, cryptotanshinone and saikosaponin B2 were found to be potent S1-RBD spike protein inhibitors, displaying considerable hydrogen bond interactions with ke... [more]
Improving the Feedforward Component for Recent Variants of Predictive Functional Control
John Anthony Rossiter, Muhammad Abdullah, Muhammad Saleheen Aftab
June 21, 2024 (v1)
Keywords: coincidence horizon, feed-forward control, pre-stabilisation, predictive functional control, preview control
A recent study demonstrated that the use of feedforward information with conventional Predictive Functional Control (PFC) leads to unexpected inconsistencies, with subsequent negative impacts on tuning and behaviour. A proposal was made to define the coincident point differently and shown to reduce the lag in the closed-loop PFC responses and applied to some systems with benign dynamics. Other recent work has looked at parameterisations of the future input to deal with challenging open-loop dynamics and significantly extended the range of problems for which PFC can be effective. This paper combines the two concepts, and thus proposes an algorithm that has both more effective and simple tuning than original PFC as well as being applicable to a range of challenging dynamics.
Experimental Study on Chrome Tanned Leather Shavings Modification—Properties and Prospective for Future Application
Dorota Gendaszewska, Paulina Pipiak, Dorota Wieczorek, Katarzyna Sieczyńska
June 21, 2024 (v1)
Subject: Materials
Keywords: chrome tanned leather shavings, FTIR analysis, heavy metal, phytotests
Chrome tanned leather shavings (CTLS) are considered one of the more difficult wastes to manage in the tanning industry. At the same time, this waste is an important source of good quality collagen. The few methods described in the literature for the valorization of these wastes usually require pre-treatment or activation. In this study, an attempt was made to see if raw chrome tanned leather shavings (CTLS) could be modified to obtain secondary raw materials with new physical properties. Glutaraldehyde, glycerol, EDCs, pectin, and tannins were selected for modification of the CTLS. The effectiveness of the processes carried out was confirmed by FTIR analysis of the materials obtained. Changes in the intensity of the characteristic collagen peak (amide I, amide II, and amide III) and changes in the position of the bands in the 1200−1000 cm−1 region were observed in the recorded spectra. The modifications introduced confirmed changes in the physical properties of samples M1−M5, includin... [more]
Heat and Mass Transfer Characteristics of Oily Sludge Thermal Desorption
Kai Li, Ao Cai, Yijun Tang, Xianyong Zhang
June 21, 2024 (v1)
Keywords: energy distribution, heat transfer, liquid evaporation, process simulation
Oily sludge is a loose material containing solid and multiple liquid components. Thermal desorption is an efficient method of disposing of liquids from oily sludge. Most existing studies have mainly discussed the effect of some external process parameters on thermal desorption, with little discussion on the heat transfer characteristics and the variation in the wet component mass of oily sludge under heating. Small-scale experiments have been performed to measure the rise in temperature and liquid phase content change of the sludge during heating. The temperature rise rate increases with material density and increases faster during the initial heating stage, while it slows down as the liquid phase evaporates. The adhesive shear stress is determined by measuring the pulling force of the test rod, which decreases with decreasing water content and increases significantly with decreasing oil phase content. Heat transfer and energy distribution models have been developed to calculate the ri... [more]
Research on the Application of Structural Topology Optimisation in the High-Precision Design of a Press Machine Frame
Zeqi Tong, Cheng Shen, Jie Fang, Mingming Ding, Huimin Tao
June 21, 2024 (v1)
Keywords: finite element analysis, press frame design, response surface method, stereo lithography appearance, topology optimisation
This article aims to optimise the structure of a press machine to enhance its stability and accuracy, as well as reduce the frame deformation during processing. The outer supporting frame of the JH31-250 press machine (Zhejiang Weili Forging Machinery Co., Ltd, Shaoxing, China) is used as a typical sample for exploring optimisation. Commercial software is utilised to conduct a finite element analysis on the three-dimensional model of the press machine frame. A topological optimisation algorithm using the solid isotropic microstructures with penalisation (SIMP) method is then applied to improve the structure of the press frame. The size of the topological structure is further refined with the response surface method and particle swarm optimisation method to ensure it is more relevant to engineering application. The analysis results indicate that the initial frame’s deformation under the static conditions is 0.4229 mm, and after optimisation, the deformed structural displacement is 0.254... [more]
Nonlinear Predictive Control of Diesel Engine DOC Outlet Temperature
Xuan Yu, Yuhua Wang, Guiyong Wang, Qianqiao Shen, Boshun Zeng, Shuchao He
June 21, 2024 (v1)
Keywords: Diesel DOC, gradient descent method, LSTM neural network, Model Predictive Control, outlet temperature, regeneration mode temperature
In the regeneration mode, precise control of the Diesel Oxidation Catalyst (DOC) outlet temperature is crucial for the complete combustion of carbon Particulate Matter (PM) in the subsequent Diesel Particulate Filter (DPF) and the effective conversion of Nitrogen Oxides (NOx) in the Selective Catalytic Reduction (SCR). The temperature elevation process of the DOC involves a series of intricate physicochemical reactions characterized by high nonlinearity, substantial time delays, and uncertainties. These factors render effective and stable control of the DOC outlet temperature challenging. To address these issues, this study proposes an approach based on Long Short-Term Memory (LSTM) neural networks for Model Predictive Control (MPC), emphasizing precise control of the Diesel Oxidation Catalyst’s outlet temperature during the regeneration mode. To tackle the system’s nonlinear characteristics, LSTM is employed to construct a predictive model for the outlet temperature of the Diesel Oxid... [more]
Preparation of Crust Type Dust Suppression Gel Based on Plant Extraction Technology for Ginkgo biloba Leaves: Characterization, Properties, and Function Mechanism
Bo Ren, Gang Zhou, Mingkun Song, Bingyou Jiang, Yuannan Zheng, Tao Fan, Shuailong Li, Jing Zhao, Haoyang Li, Hongrui Qu
June 21, 2024 (v1)
Subject: Materials
Keywords: crust type, dust suppression materials, Ginkgo biloba leaves, molecular dynamics simulation, waste utilization
The coal industry plays an essential role in China’s economic development, and issues such as occupational health and environmental pollution caused by coal dust have attracted a great deal of attention. In accordance with the principles of environmental protection and waste management, this study used carboxymethyl ginkgo cellulose (CL) extracted and modified from Ginkgo biloba leaves as a matrix, and a graft copolymerized with sodium 3-allyloxy-1-hydroxy-1-propanesulfonate (AHPS) and N-isopropylacrylamide (NIPAM) monomers to prepare low-cost, environmentally friendly, and high-performance coal dust suppression (C-A-N). By optimizing fitting experimental data through three factors and two response surface analyses, the optimal dust suppression efficiency ratio was determined to be 4:8:5, and its swelling and water retention properties were analyzed. The microstructure, chemical reaction process, combustion performance and crusting property of the dust suppression gel were analyzed usi... [more]
Research on Inbound Jobs’ Scheduling in Four-Way-Shuttle-Based Storage System
Zhaoyun Wu, Yingxu Zhang, Li Li, Zhongwei Zhang, Binbin Zhao, Yehao Zhang, Xuewu He
June 21, 2024 (v1)
Keywords: elevator, FFSP problem, four-way shuttle, improved genetic algorithm, job scheduling
The four-way-shuttle-based storage and retrieval system is a recent innovative intelligent vertical warehousing system that has been widely applied in manufacturing and e-commerce environments due to its high flexibility and density. As a complex multi-device cooperative operational system, this system features the parallel operation of multiple elevators and four-way shuttles. During large-scale-batch inbound operations, the quality of scheduling solutions for inbound-operation equipment significantly impacts the system’s efficiency and performance. In this paper, a detailed analysis of the inbound-operation process in the system is conducted, taking into consideration the motion characteristics of both the elevators and four-way shuttles. Furthermore, we establish operational time constraints that account for equipment acceleration and deceleration characteristics and introduce a flexible flow-shop-scheduling model to address the scheduling problem in the system. Additionally, we pro... [more]
Numerical Study of a Heat Exchanger with a Rotating Tube Using Nanofluids under Transitional Flow
Mohamed A. El-Magid Mohamed, Andrés Meana-Fernández, Juan M. González-Caballín, Anthony Bowman, Antonio José Gutiérrez-Trashorras
June 21, 2024 (v1)
Subject: Materials
Keywords: concentric tube, heat transfer, hybrid nanofluids, NTU, single-phase flow
Improvements in heat exchanger thermal efficiency are crucial for achieving energy use and cost reductions. The use of nanofluids and the rotation of the exchanger inner tube may enhance heat transfer and exchanger efficiency. In this work, after having performed experiments on such a heat exchanger, a three dimensional numerical model was developed to simulate the transitional forced convection flow of a horizontal double-tube heat exchanger, with the aim of obtaining insight into the effects of the inner tube rotation, fluid flow rate and type of nanofluid employed. It was found that an increase in the nanoparticle concentration up to 3% increased the exchanger efficiency. Al2O3, Al2O3-Cu and Cu-water nanofluids were studied, with the Cu-water being the fluid with the best performance (19.33% improvement). Heat transfer was enhanced with inner tube rotation up to 500 rpm (41.2%). Nevertheless, pressure drop and friction values were increased due to both phenomena, leading to higher p... [more]
Effect of Choice of Drilling Kinematic System on Cylindricity Deviation, Roundness Deviation, Diameter Error and Surface Roughness of Holes in Brass Alloy
Mateusz Bronis, Bartlomiej Krawczyk, Stanislaw Legutko
June 21, 2024 (v1)
Subject: Materials
Keywords: ANOVA, brass alloy, drilling, Grey Relational Analysis, hole quality, kinematic system, surface texture
This article presents the results of an experimental study on the effect of the selection of kinematic system for the drilling process on the cylindricity deviation, roundness deviation, diameter error and surface roughness of holes in brass alloy. Three different kinematic systems based on the dependence of the direction of rotation of the workpiece and the drill bit were used. The drill bit was mounted in an axially driven holder that allowed it to be put into motion. Cutting tests were conducted at three different spindle speeds and three different feed rates per revolution (27 tests in total). A static ANOVA analysis was used to evaluate the effect of each input parameter on each output parameter. The results of this work have practical applications in machining. The following input parameters of the drilling process should be used to obtain the smallest values of each output parameter: for CYL, n = 4775 rpm, fn = 0.14 mm/rev and KIN III; for RON, n = 4775 rpm, fn = 0.1 or 0.12 mm/... [more]
Enhancing LightGBM for Industrial Fault Warning: An Innovative Hybrid Algorithm
Shuai Li, Nan Jin, Azadeh Dogani, Yang Yang, Ming Zhang, Xiangyun Gu
June 21, 2024 (v1)
Subject: Optimization
Keywords: Arithmetic Optimization Algorithm, fault warning, hybrid algorithm, hyperparameter optimization, LightGBM
The reliable operation of industrial equipment is imperative for ensuring both safety and enhanced production efficiency. Machine learning technology, particularly the Light Gradient Boosting Machine (LightGBM), has emerged as a valuable tool for achieving effective fault warning in industrial settings. Despite its success, the practical application of LightGBM encounters challenges in diverse scenarios, primarily stemming from the multitude of parameters that are intricate and challenging to ascertain, thus constraining computational efficiency and accuracy. In response to these challenges, we propose a novel innovative hybrid algorithm that integrates an Arithmetic Optimization Algorithm (AOA), Simulated Annealing (SA), and new search strategies. This amalgamation is designed to optimize LightGBM hyperparameters more effectively. Subsequently, we seamlessly integrate this hybrid algorithm with LightGBM to formulate a sophisticated fault warning system. Validation through industrial c... [more]
Effects of the PMMA Molecular Weight on the Thermal and Thermo-Oxidative Decomposition as the First Chemical Stage of Flaming Ignition
Antonio Galgano, Colomba Di Blasi
June 21, 2024 (v1)
Keywords: decomposition kinetics, Modelling, molecular weight, piloted ignition, PMMA, spontaneous ignition
The piloted and the spontaneous ignition of low and high molecular weight (LMW and HMW) polymethyl methacrylate are simulated using a one-dimensional condensed-gas phase model for constant heat fluxes in the range of 25−150 kW/m2. Purely thermal (nitrogen) and thermo-oxidative (air) decomposition is considered, described by a single and four-step kinetics for the low and high molecular weight polymer, respectively. Different optical properties are also examined. The same trends of the ignition time and other ignition parameters are always observed. Due to a more significant role of the chemical kinetics, the effects of the sample molecular weight and reaction atmosphere are higher at low heat fluxes. Times are shorter for the black HMW samples and thermo-oxidative kinetics. For piloted ignition, factors are around 2.8−1.6, whereas for thermal decomposition, they are 1.3−1.2. The corresponding figures are 1.8−1.3 and 1.3−1.1, in the same order, for the spontaneous ignition. Overall, the... [more]
Optimization Strategy for Shared Energy Storage Operators-Multiple Microgrids with Hybrid Game-Theoretic Energy Trading
Yi Chen, Shan He, Weiqing Wang, Zhi Yuan, Jing Cheng, Zhijiang Cheng, Xiaochao Fan
June 21, 2024 (v1)
Keywords: electric vehicle clusters, hybrid game theory, KKT conditions, multiple microgrids, shared energy storage operators, strong duality theory
To address the issue of low utilization rates, constrained operational modes, and the underutilization of flexible energy storage resources at the end-user level, this research paper introduces a collaborative operational approach for shared energy storage operators in a multiple microgrids (ESO-MGs) system. This approach takes into account the relation of electricity generated by MGs and the integration of diverse energy storage resources managed by ESO. A hybrid game-theoretic energy trading strategy is employed to address the challenges associated with energy trading and revenue distribution in this joint operational mode. Firstly, a multi-objective master−slave game optimization model is developed with the objective of maximizing the revenue earned by shared energy storage operators while simultaneously minimizing the operational costs of multiple microgrids. Secondly, acknowledging the peer-to-peer (P2P) energy sharing dynamics inherent in the multiple microgrid system, a non-co-o... [more]
Autonomous Hydrodistillation with a Digital Twin for Efficient and Climate Neutral Manufacturing of Phytochemicals
Alexander Uhl, Larissa Knierim, Theresa Höß, Marcel Flemming, Axel Schmidt, Jochen Strube
June 21, 2024 (v1)
Keywords: autonomous operation, climate neutrality, digital twin, green technology, hydrodistillation, natural products, phytochemicals, process analytical technology, Renewable and Sustainable Energy
Hydrodistillation is traditionally a green technology for the manufacturing of natural products that are volatile. As well as acknowledged process intensification methods such as microwave support for energy efficiency to move towards climate neutral operation, digital twins combined with process analytical technology for advanced process control enables reliable operation of an optimal operation point regarding lowest cost of goods, as well as lowest global warming potential equivalent. A novel process control enabled by digital twin technology has shown to reduce the ecological footprint of the extraction by up to 46.5%, while reducing the cost of extraction by 22.4%. Additionally, skilled operator time is reduced, and the sustainable plant material is utilized most efficiently. The approach is ready to apply, but broad industrialization seems to be held back by unclear business cases and lack of comprehension of decision makers. This is in drastic contrast to the political demand fo... [more]
Numerical Reservoir Simulation of Supercritical Multi-Source and Multi-Component Steam Injection for Offshore Heavy Oil Development
Qiang Fu, Zhouyuan Zhu, Junjian Li, Hongmei Jiao, Shuoliang Wang, Huiyun Wen, Yongfei Liu
June 21, 2024 (v1)
Keywords: mineral dissolution, offshore heavy oil development, pyrolysis reaction, supercritical multi-source and multi-component steam, thermal reservoir simulation
We present the workflow for numerical reservoir simulation of supercritical multi-source and multi-component steam injection for offshore heavy oil development. We have developed unique techniques in a commercial reservoir simulator to implement the thermal properties of supercritical multi-source and multi-component steam, the pyrolysis chemical reactions, the temperature-dependent relative permeability, and the process of partially dissolving the sandstone rock to enhance the matrix permeability in a commercial reservoir simulator. Simulations are conducted on the type pattern reservoir model, which represents one of the heavy oil fields in CNOOC’s Bohai Bay oil field. Simulation input parameters are calibrated based on laboratory experiments conducted for supercritical multi-source and multi-component steam injection. Simulation results have shown clear improvements in injecting supercritical multi-source and multi-component steam in offshore heavy oil reservoirs compared to the nor... [more]
The Influence of Wettability Effect and Adsorption Thickness on Nanoconfined Methane Phase Behavior: Vapor-Liquid Co-Existence Curves and Phase Diagrams
Guodai Wu, Chunlin Zeng, Lijun Cheng, Jinhua Luan, Ruigang Zhang, Ziwei Chen, Yu Pang, Zheng Sun
June 21, 2024 (v1)
Keywords: Adsorption, methane phase behavior, nanopores, vapor-liquid co-existence, wettability
Research interest in the behavior of methane inside nanopores has been growing, driven by the substantial geological reserves of shale gas and coalbed methane. The phase diagram of methane in nanopores differs significantly from its bulk state, influencing its existing form and pertinent physical properties—such as density and viscosity—at specific pressures and temperatures. Currently, there is a lack of effort to understand the nanoconfinement effect on the methane phase diagram; this is a crucial issue that needs urgent attention before delving into other aspects of nanoconfined methane behavior. In this study, we establish a fully coupled model to predict the methane phase diagram across various scales. The model is based on vapor-liquid fugacity equilibrium, considering the shift in critical pressure and temperature induced by pore size shrinkage and adsorption-phase thickness. Notably, our proposed model incorporates the often-overlooked factor of capillary pressure, which is gre... [more]
Transition Metal Complexes with Amino Acids, Peptides and Carbohydrates in Catalytic Asymmetric Synthesis: A Short Review
Yuliya Titova
June 21, 2024 (v1)
Subject: Biosystems
Keywords: amino acid, asymmetric synthesis, carbohydrate, Catalysis, ligand, modified, organic catalytic synthesis, transition metal complex
The present review is devoted to the application of transition metal complexes with such ligands as amino acids, peptides and carbohydrates in catalysis. The literature published over the past 20 years is surveyed. Among the distinctive features of these ligands are their versatility, optical activity, stability and availability. Furthermore, depending on the specific synthetic task to be solved, these ligands open up almost infinite opportunity for modification. Largely thanks to their multifaceted reactivity, transition metal complexes with amino acids, peptides and carbohydrates can catalyze most of the known chemical reactions affording optically pure compounds. In this review, the emphasis is placed upon C(sp3)−H activation, cross-coupling and hydrogenation (including traditional hydrogenation in the presence of hydrogen gas and hydrogenation with hydrogen transfer) reactions. The choice is not accidental, since these reactions on the one hand display the catalytic versatility of... [more]
Showing records 1 to 25 of 1034. [First] Page: 1 2 3 4 5 Last