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Showing records 1737 to 1761 of 43292. [First] Page: 1 67 68 69 70 71 72 73 74 75 Last
Synthesis, Characterization and Power Factor Estimation of SnSe Thin Film for Energy Harvesting Applications
Kaleem Ahmad, Zeyad Almutairi, Syed Mansoor Ali, Redhwan Almuzaiqer, Chunlei Wan, Abdul Sayeed
June 5, 2024 (v1)
Subject: Materials
Keywords: energy harvesting, power factor, SILAR, SnSe thin film, thermoelectric
In this work, a simple, cost-effective successive ionic layer adsorption and reaction (SILAR) deposition technique has been used to deposit a high-quality tin selenide (SnSe) thin film onto a glass substrate. Structural, morphologic, and thermoelectric properties have been characterized for the prepared thin film. X-ray diffraction (XRD) results of the SnSe thin film reveal an orthorhombic structure phase. The morphological properties of the prepared thin films have been studied using field emission scanning electron microscopy (FESEM). The stoichiometric composition of the deposited thin film and the elemental binding energies of the Sn and Se elements have been investigated with energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The Fourier transformation infrared (FTIR) spectrum of the SnSe thin film displays vibrational modes of chalcogenides bonds. These results suggest that the developed thin film is crystalline, uniform, and without impurities and i... [more]
A New Empirical Correlation for Pore Pressure Prediction Based on Artificial Neural Networks Applied to a Real Case Study
Ahmed Abdulhamid Mahmoud, Bassam Mohsen Alzayer, George Panagopoulos, Paschalia Kiomourtzi, Panagiotis Kirmizakis, Salaheldin Elkatatny, Pantelis Soupios
June 5, 2024 (v1)
Keywords: artificial neural network, Epsilon oil field, pore pressure, well log data
Pore pressure prediction is a critical parameter in petroleum engineering and is essential for safe drilling operations and wellbore stability. However, traditional methods for pore pressure prediction, such as empirical correlations, require selecting appropriate input parameters and may not capture the complex relationships between these parameters and the pore pressure. In contrast, artificial neural networks (ANNs) can learn complex relationships between inputs and outputs from data. This paper presents a new empirical correlation for predicting pore pressure using ANNs. The proposed method uses 42 datasets of well log data, including temperature, porosity, and water saturation, to train ANNs for pore pressure prediction. The trained model, with the Bayesian regularization backpropagation function, predicts the pore pressure with an average absolute percentage error (AAPE) and correlation coefficient (R) of 4.22% and 0.875, respectively. The trained ANN is then used to develop a ne... [more]
The TPRF: A Novel Soft Sensing Method of Alumina−Silica Ratio in Red Mud Based on TPE and Random Forest Algorithm
Fanguang Meng, Zhiguo Shi, Yongxing Song
June 5, 2024 (v1)
Keywords: alumina–silica ratio, random forest algorithm, soft sensor, TPE algorithm
The online measurement of the aluminum−silicon ratio of red mud in the dissolution stage of the Bayer alumina production process is difficult to achieve. The offline assay method has a high cost and strong time delay. Soft sensors are an effective and economical method to solve such problems. In this paper, a hybrid model (TPRF model) based on a tree-structured Parzen estimator (TPE) optimized random forest (RF) algorithm is proposed to measure the Al−Si ratio of red mud. The probability distribution of the hyperparameters of the random forest model is estimated by combining the TPE optimization algorithm with the random forest algorithm. According to this probability distribution, the hyperparameters of the random forest algorithm are adjusted in the parameter search space to obtain the best combination of hyperparameters. We established a TPRF soft sensing model based on the optimal combination of hyperparameters. The results show that the best performance of the TPRF model is a mean... [more]
Sodium Alginate−Soy Protein Isolate−Chitosan−Capsaicin−Nanosilver Multifunctional Antibacterial Composite Gel
Zhichao Zhang, Meizi Huang, Kejian Shen, Yucai He, Youyan Liu
June 5, 2024 (v1)
Subject: Biosystems
Keywords: antibacterial ability, dye adsorption, microbial pollution, milk preservation, nanosilver antibacterial composite
We constructed a sodium alginate/soy protein isolate/chitosan gel system and incorporated silver nanoparticles reduced by capsaicin into the system, forming a sodium alginate−soy protein isolate−chitosan−capsaicin−silver nanoparticle composite gel (SA/SPI/CTS/CAP/Ag). In tests, the SA/SPI/CTS/CAP/Ag gel exhibited excellent antimicrobial properties. Using the agar diffusion method, the inhibition zone diameter for Staphylococcus aureus was determined to be 29.5 mm. Soy protein isolate (SPI), containing a large number of hydrophobic amino acid residues, effectively enhanced the moisture retention capability of the gel and improved its stability to a certain extent at an appropriate addition concentration. In a milk preservation experiment, the SA/SPI/CTS/CAP/Ag gel significantly extended the shelf-life of the milk. In dye adsorption experiments, the adsorption curve of the SA/SPI/CTS/CAP/Ag gel well fitted a pseudo-second-order kinetic model. It showed a degree of adsorption capacity for... [more]
Production Capacity Prediction and Optimization in the Glycerin Purification Process: A Simulation-Assisted Few-Shot Learning Approach
Tawesin Jitchaiyapoom, Chanin Panjapornpon, Santi Bardeeniz, Mohd Azlan Hussain
June 5, 2024 (v1)
Keywords: few-shot learning, glycerin purification, production optimization, simulation-assisted
Chemical process control relies on a tightly controlled, narrow range of margins for critical variables, ensuring process stability and safeguarding equipment from potential accidents. The availability of historical process data is limited to a specific setpoint of operation. This challenge raises issues for process monitoring in predicting and adjusting to deviations outside of the range of operational parameters. Therefore, this paper proposes simulation-assisted deep transfer learning for predicting and optimizing the final purity and production capacity of the glycerin purification process. The proposed network is trained by the simulation domain to generate a base feature extractor, which is then fine-tuned using few-shot learning techniques on the target learner to extend the working domain of the model beyond historical practice. The result shows that the proposed model improved prediction performance by 24.22% in predicting water content and 79.72% in glycerin prediction over t... [more]
Experimental Investigation into the Process of Hydraulic Fracture Propagation and the Response of Acoustic Emissions in Fracture−Cavity Carbonate Reservoirs
Hanzhi Yang, Lei Wang, Zhenhui Bi, Yintong Guo, Junchuan Gui, Guokai Zhao, Yuting He, Wuhao Guo, Guozhou Qiu
June 5, 2024 (v1)
Keywords: acoustic emission monitoring, cavity cluster distribution, fracture propagation, fracture–cavity carbonate, interaction behavior
Fracture−cavity carbonate reservoirs account for a considerable proportion of oil and gas resources. Because of the complicated relationships between cavities, fractures and pores in these reservoirs, which are defined as cavity clusters, fracturing technology is employed to enhance their hydrocarbon productivity. However, almost all previous studies have just considered the effect of a single natural cavity or fracture on the propagation of a hydraulic fracture; therefore, the mechanism by which a hydraulic fracture interacts with a cavity cluster needs to be clarified. In this study, cavity clusters with different distributions were accurately prefabricated in synthetically made samples, and large-scale simulation equipment was employed to systematically perform fracturing experiments considering different horizontal differential stress levels. Meanwhile, the hydraulic fracture propagation behaviors were comprehensively analyzed through fracture morphology, fracturing curves, the com... [more]
Antioxidant Activity of Carob Tree (Ceratonia siliqua L.) Leaf Extracts Obtained by Advanced Extraction Techniques
Ena Cegledi, Erika Dobroslavić, Zoran Zorić, Maja Repajić, Ivona Elez Garofulić
June 5, 2024 (v1)
Keywords: antioxidant activity, carob leaves, green extraction, microwave-assisted extraction, polyphenols, pressurized liquid extraction, ultrasound-assisted extraction
Carob (Ceratonia siliqua L.) is a widely spread Mediterranean evergreen tree whose plant parts are rich in bioactive compounds with potential for application in functional food production. Carob leaves are the least explored part of the plant, and the main compounds of interest are polyphenols. Advanced extraction techniques, such as pressurized liquid (PLE), microwave-assisted (MAE) and ultrasound-assisted (UAE) extraction have not been sufficiently explored for their potential in extracting these compounds. Therefore, the aim of this paper was to optimize the parameters (temperature and time) of PLE, MAE and UAE of carob leaf polyphenols, characterize the individual compounds by ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS2) and determine the antioxidant activity of the extracts. The optimal temperature and time were 160 °C/5 min for PLE, resulting in a total phenolic content of 68.21 mg of gallic acid equivalents (GAE) g−1. For MAE and UAE, the opti... [more]
Characteristic Analysis and Coating Application of the Innovative HVOF System Based on the Digital Model
Mingxia Yan, Xiaojing Yuan, Qingdong Su, Zhensheng Sun, Guan Zhao, Bailin Zha
June 5, 2024 (v1)
Keywords: AMESim, digital model, dynamic characteristics, HVOF, spray parameter design
In view of the poor working conditions, high cost and time-consuming parameter design of the traditional spray process, an innovative HVOF thermal spray system based on the digital model has been established by this study to improve coating performance and optimize scheme design rapidly. In particular, the digital model of the oxygen/kerosene HVOF spray system is designed on the AMESim multidisciplinary simulation platform for the first time, and the engineering prototype has been successfully developed. Thus, an efficient design method based on the digital model was proposed, according to which the spray control parameters such as oxygen and kerosene flow are obtained conveniently under a combustion chamber pressure of 1.0 MPa and 2.0 MPa, respectively. The error between the simulation and experiment results was generally less than 5%, and the dynamic characteristics of the key components in the actual spray system were well predicted, suggesting that the dynamic response time of the... [more]
The Influence of Coal Body Structure on Coal Fines’ Output Characteristics in the Southern Qinshui Basin
Junshan Ren, Zhou Zhang, Liru Xing, Pengxiang Wang, Wanying Yu, Piao Long
June 5, 2024 (v1)
Keywords: coal body structure, coal fines’ output characteristics, coalbed methane, control mechanism, Qinshui Basin
Large amounts of coal fines are discharged from coalbed methane wellheads in the Qinshui Basin, obstructing the continuity of drainage; their extraction poses significant hazards. This paper recognized the coal body structure of 30 coalbed methane wells in the study region, using the integrated identification method of logging curve and tectonic curvature. The research found that the primary structural coal output of coal fines concentration averaged 0.237 g/L, the average content of particle size 10−100 μm was 58.88%, the average range of particle size 1−10 μm was 22.91%, and the main form was irregular columns and lumps. The average concentration of fractured structural coal fines was 1.169 g/L, the average content of particle size 10−100 μm was 41.73%, the average range of particle size 1−10 μm was 31.77%, and the main form was balls and lumps. The average concentration of granulated-mylonitic structured coal fines was 3.156 g/L, the average content of particle size 10−100 μm was 25... [more]
Mitigation of Renewable Energy Source Production Variability in Residential Stock through Small-Scale Gas−Liquid Energy Storage Technology Application
Andrea Vallati, Miriam Di Matteo, Laura Pompei, Fabio Nardecchia, Costanza Vittoria Fiorini
June 5, 2024 (v1)
Keywords: building energy, CAES, Energy Efficiency, Energy Storage, experimental campaign, Power-to-Power, prototype, Renewable and Sustainable Energy, self-consumption, thermodynamic model
Despite renewable energy source integration being a well-established requirement in international policies, energy systems still face some unresolved issues, including the intermittence of production. To tackle this problem, a viable solution could comprise the off-peak storage of electricity production excess, to be consumed later during peak-load hours. The transition from the diffuse pattern of centralized generation to the distributed model, involving energy communities, suggests an additional aspect to manage: the spatial constraints of systems for domestic applications. Compressed-air energy storage represents a promising Power-to-Power technology for small-scale energy integration. This study proposes the application of a gas−liquid energy storage system (GLES) in a residential building, using renewable energy excess from a photovoltaic (PV) array. The performance of the proposed system, whose operation involves the compression of the gaseous mass through a piston operated by mi... [more]
Fluorine-Free and Transparent Superhydrophobic Coating with Enhanced Anti-Icing and Anti-Frosting Performance by Using D26 and KH560 as Coupling Agents
Ting Xiao, Yudian Wang, Xia Lang, Siyu Chen, Lihua Jiang, Fujun Tao, Yequan Xiao, Xinyi Li, Xinyu Tan
June 5, 2024 (v1)
Subject: Materials
Keywords: anti-frosting, anti-icing, coupling agents, D26, KH560
Superhydrophobic surfaces with non-wetting characteristics have been considered to be potential candidates for ice/frost prevention. In this study, a transparent superhydrophobic coating was created by using a simple method that employed (3-glycidoxypropyl) trimethoxysilane (KH560) and 1,2-Bis (trimethoxysilyl) ethane (D26) as coupling agents and epoxy resin (E51) as an adhesive. The synergy between KH560 and D26 significantly improves the long-term outdoor durability, anti-icing, and anti-frosting performance of the superhydrophobic coating. The coating also has good acid and alkali resistance, UV resistance, and durability. The obtained SiO2@E51@KH560@D26 can delay the freezing time of water by 1974 s, much longer than bare glass (345 s) and also longer than the coatings with only D26 (932 s) or with only KH560 (1087 s). Moreover, the SiO2@E51@KH560@D26 showed an improved anti-frosting capability compared with the other three samples and better maintained its superhydrophobic propert... [more]
Analyzing the Effect of Extraction Parameters on Phenolic Composition and Selected Compounds in Clove Buds Using Choline Chloride and Lactic Acid as Extraction Agents
Petra Strižincová, Igor Šurina, Michal Jablonský, Veronika Majová, Aleš Ház, Katarína Hroboňová, Andrea Špačková
June 5, 2024 (v1)
Subject: Biosystems
Keywords: choline chloride, clove buds, design of experiment, eugenol, Extraction, lactic acid
Utilizing a deep eutectic solvent-like mixture such as choline chloride and lactic acid in a 1:2 molar ratio, clove buds underwent extraction. Furthermore, the determination of the primary components in the clove extracts, namely eugenol, eugenol acetate, and β-caryophyllene, was conducted using the HPLC-DAD method. The total phenolic content (TPC) was also established. Extraction conditions using choline chloride and lactic acid encompassed variables such as extraction temperature (within the range of 40 to 80 °C), water addition (ranging from 5.6 to 40%), and extraction time (ranging from 30 to 90 min). Optimal operational conditions for TPC were pinpointed at 77 °C, 30 min, and a water addition of 40%. The findings showed that clove extracts obtained at 60 °C, 22.8%, and 30 min had the highest amount of eugenol (307.26 ± 8.44 mg/g dry raw material).
Algorithm for Correlation Diagnosis in Multivariate Process Quality Based on the Optimal Typical Correlated Component Pair Group
Qing Niu, Shujie Cheng, Zeyang Qiu
June 5, 2024 (v1)
Keywords: correlation decomposition, correlation diagnosis, quality component pairs, T2 control chart
Correlation diagnosis in multivariate process quality management is an important and challenging issue. In this paper, a new approach based on the optimal typical correlated component pair group (OTCCPG) is proposed. Firstly, the theorem of correlation decomposition is proved to decompose the correlation of all the quality components as serial correlations of component pairs, and then according to the transitivity of correlations of component pairs, the decomposition result is represented by a correlation set of typical correlated component pairs. Finally, an algorithm for OTCCPG based on the maximum correlation spanning tree (MCST) is proposed, and T2 control charts to monitor the correlations of component pairs in OTCCPG are established to form the correlation diagnostic system. Theoretical analysis and practice prove that the proposed method could reduce the space complexity of the diagnostic system greatly.
Effect of Acid-Injection Mode on Conductivity for Acid-Fracturing Stimulation in Ultra-Deep Tight Carbonate Reservoirs
Jiangyu Liu, Dengfeng Ren, Shaobo Feng, Ju Liu, Shiyong Qin, Xin Qiao, Bo Gou
June 5, 2024 (v1)
Subject: Other
Keywords: acid-fracture morphology, acid-injection mode, conductivity, field application, multi-stages alternating acid fracturing, ultra-deep carbonate reservoirs
The conductivity of acid-etched fractures and the subsequent production response are influenced by the injection mode of the fracturing fluid and acid fluid during acid fracturing in a carbonate reservoir. However, there has been a lack of comprehensive and systematic experimental research on the impact of commonly used injection modes in oilfields on conductivity, which directly affects the optimal selection of acid-fracturing injection modes. To address this gap, the present study focuses on underground rock samples, acid systems, and fracturing fluid obtained from ultra-deep carbonate reservoirs in the Fuman Oilfield. Experimental investigations were conducted to examine the conductivity of hydraulic fractures etched by various types of acid fluids under five different injection modes: fracturing fluid + self-generating acid or cross-linked acid; fracturing fluid + self-generating acid + cross-linked acid. The findings demonstrate that the implementation of multi-stage alternating a... [more]
The Influence of Slim Tube Length on the Minimum Miscibility Pressure of CO2 Gas−Crude Oil
Yanchun Su, Renfeng Yang, Lijun Zhang, Xiaofeng Tian, Xugang Yang, Xiaohan Shu, Qinyuan Guo, Fajun Zhao
June 5, 2024 (v1)
Keywords: CO2 flooding, formation oil, MMP, slim tube length
This study focuses on the Bozhong 25-1 oilfield formation oil as the experimental subject, systematically investigating the influence of different slim tube lengths (1 m, 12.5 m, 20 m, and 25 m) on the minimum miscibility pressure (MMP) of the CO2 and formation oil mixture system. Through slim tube experiments, the interaction process of CO2 with formation oil in slim tubes of different lengths was simulated, with a particular focus on analyzing how changes in slim tube length affect the MMP. The experiments revealed an important phenomenon: as the slim tube length gradually increased from shorter dimensions, the MMP showed a decreasing trend; when the slim tube length reached 12.5 m, this trend stabilized, meaning that further increasing the slim tube length no longer led to significant changes in the MMP, with its stable value determined to be 27.86 MPa. This phenomenon can be explained within the theoretical framework of fluid dynamics and interfacial science, where several key fact... [more]
Low-Carbon-Oriented Capacity Optimization Method for Electric−Thermal Integrated Energy System Considering Construction Time Sequence and Uncertainty
Yubo Wang, Xingang Zhao, Yujing Huang
June 5, 2024 (v1)
Keywords: carbon emissions, economic optimization, ladder carbon trading, multi-stage planning, renewable energy utilization
The interdependence of various energy forms and flexible cooperative operation between different units in an integrated energy system (IES) are essential for carbon emission reduction. To address the planning problem of an electric−thermal integrated energy system under low-carbon conditions and to fully consider the low carbon and construction sequence of the integrated energy system, a low-carbon-oriented capacity optimization method for the electric−thermal integrated energy system that considers construction time sequence (CTS) and uncertainty is proposed. A calculation model for the carbon transaction cost under the ladder carbon trading mechanism was constructed, and a multi-stage planning model of the integrated energy system was established with the minimum life cycle cost, considering carbon transaction cost as the objective function, to make the optimal decision on equipment configuration in each planning stage. Finally, a case study was considered to verify the advantages of... [more]
Research on the Process of Laser Cladding Ni60 Coating on High-Nickel Cast Iron Surfaces
Shunhu Chen, Aixin Feng, Chunlun Chen, Xiangyu Song
June 5, 2024 (v1)
Subject: Materials
Keywords: high nickel cast iron, laser cladding, microstructure, Ni60, process parameters, temperature field
In order to achieve high-performance coatings on the surface of electric submersible pump impellers, it is crucial to optimize the laser cladding process parameters. Using Ansys 2021 R1 commercial software, a numerical simulation of laser cladding Ni60 powder on high nickel cast iron was conducted. The simulation utilized a 3D Gaussian heat source, parametric language, and life−death unit technology to replicate the characteristics of synchronous powder delivery laser cladding. The study focused on analyzing the temperature field cloud map and molten pool size under different laser power and scanning speeds, narrowing down the process parameter window, selecting optimized laser power and scanning speed, and assessing the changes in surface morphology, melting height and width, dilution rate, microhardness, and microstructure of the laser cladding coating. Results indicate that the coating width and thickness increase with higher laser power and lower scanning speeds. The microstructure... [more]
Modeling and Switched Control of Modular Reconfigurable Flight Array for Faulty Redundancy
Bin Ren, Chunxi Yang, Xiufeng Zhang, Wenyuan Mao
June 5, 2024 (v1)
Keywords: average dwell time, modular reconfigurable flight array, segmented Lyapunov function, switched system
The modular reconfigurable flight array (MRFA) is composed of multiple identical flight unit modules, which has several advantages such as structural variability, strong versatility, and low cost. Due to the redundant properties of MRFA, it keeps stable by adopting a suitable control law when it suffers actuator fault or actively stops some actuators. To address the attitude stability issue of the modular flight array when actuators actively stop or encounter failures during the flight process, a modeling method based on a switched system is proposed at first, and an arbitrary switched controller design method based on the segmented Lyapunov functions and the average dwell time is also given. By introducing the actuator efficiency matrix, the dynamic switched model of the modular flight array is described. Then, a group of arbitrary switched linear feedback gains is designed to ensure the exponential stability of the flight array if the switched process satisfies the constraint of the... [more]
Coupled Oxygen-Enriched Combustion in Cement Industry CO2 Capture System: Process Modeling and Exergy Analysis
Leichao Wang, Bin Shi
June 5, 2024 (v1)
Keywords: CCUS, exergy analysis, oxygen-enriched combustion, sensitivity analysis
The cement industry is regarded as one of the primary producers of world carbon emissions; hence, lowering its carbon emissions is vital for fostering the development of a low-carbon economy. Carbon capture, utilization, and storage (CCUS) technologies play significant roles in sectors dominated by fossil energy. This study aimed to address issues such as high exhaust gas volume, low CO2 concentration, high pollutant content, and difficulty in carbon capture during cement production by combining traditional cement production processes with cryogenic air separation technology and CO2 purification and compression technology. Aspen Plus® was used to create the production model in its entirety, and a sensitivity analysis was conducted on pertinent production parameters. The findings demonstrate that linking the oxygen-enriched combustion process with the cement manufacturing process may decrease the exhaust gas flow by 54.62%, raise the CO2 mass fraction to 94.83%, cut coal usage by 30%, a... [more]
Integrated Design and Control of a Sustainable Stormwater Treatment System
Ricardo Balcazar, José de Jesús Rubio, Mario Alberto Hernandez, Jaime Pacheco, Rogel Retes-Mantilla, Francisco Javier Rosas, Alejandro Zacarías, María Teresa Torres-Mancera, Eduardo Orozco, Gabriela Saavedra González, Israel Zermeño Caballero
June 5, 2024 (v1)
Keywords: automatic control, automation, Industry 4.0, rainwater treatment
In this work, issues of water separation and purification are addressed, where, in order to achieve the desired results, it is necessary to use several disciplines such as classical physics, biotechnology, automatic control, automation, and applications of industry 4.0. Further, the need for comprehensive and automated solutions for rainwater treatment in the agricultural sector is addressed. This research focuses on designing and implementing a system adapted to these needs using Siemens technologies. The methodology ranges from the design of the Piping and Instrumentation Diagram (P&ID) to the implementation of the interface, incorporating Siemens technologies for data acquisition, electrical connections, treatment programming, and PID controller design. The results show significant advances in the development of the system, highlighting the effectiveness of automation and the HMI-PLC human−machine interface in process monitoring and control. These findings support the viability of a... [more]
Sensitive and Cost-Effective TLC-Densitometric Method for Determination of Metronidazole and Tinidazole in Tablets
Alina Pyka-Pająk
June 5, 2024 (v1)
Subject: Materials
Keywords: densitometry, metronidazole, pharmaceutical preparation, tinidazole, TLC
A sensitive, easy-to-use, fast, and cost-effective TLC-densitometric method was developed for the separation of metronidazole, secnidazole, ornidazole, tinidazole, and 2-methyl-5-nitroimidazole and for the determination of metronidazole and tinidazole in Metronidazole Polpharma and Tinidazolum Polpharma tablets. Analyses were performed on chromatographic plates precoated with silica gel 60F254 using chloroform + methanol + diethylamine in a volume ratio of 9:1:1 as the optimal mobile phase. The method has been validated. The intraday and interday precision values for the three different concentrations ranged from 0.99% to 1.48% and 0.89% to 1.76%, and the precision values ranged from 1.13% to 2.48% and 0.95% to 2.49% for metronidazole and tinidazole, respectively. The limit of quantification (LOQ) was 0.036 and 0.066 µg/spot for metronidazole and tinidazole, respectively. The mean recovery was 103.1% and 100.6% for metronidazole and tinidazole, respectively. The content of metronidazol... [more]
Enhancing Accuracy in Numerical Simulations for High-Speed Flows: Integrating High-Order Corrections with Weighted Essentially Non-Oscillatory Flux
Yonghua Yan, Yong Yang, Shiming Yuan, Caixia Chen
June 5, 2024 (v1)
Keywords: MWCS, numerical scheme, WENO
This study introduces a novel method to enhance numerical simulation accuracy for high-speed flows by refining the weighted essentially non-oscillatory (WENO) flux with higher-order corrections like the modified weighted compact scheme (MWCS). Numerical experiments demonstrate improved sharpness in capturing shock waves and stability in complex conditions like two interacting blast waves. Key highlights include simultaneous capture of small-scale smooth fluctuations and shock waves with precision surpassing the original WENO and MWCS methods. Despite the significantly improved accuracy, the extra computational cost brought by the new method is only marginally increased compared to the original WENO, and it outperforms MWCS in both accuracy and efficiency. Overall, this method enhances simulation fidelity and effectively balances accuracy and computational efficiency across various problems.
Biosand Reactors for Municipal and Industrial Wastewater Treatment: Status Quo, Challenges and Opportunities
Pamela Jean Welz
June 5, 2024 (v1)
Subject: Environment
Keywords: biodegradation, hydraulic, organic loading, passive, slow sand filter
Biosand reactors (BSRs), alternatively known as slow or biological sand filters, are passive systems that are used to remove contaminants from domestic wastewater, industrial wastewater and drinking water. This review focuses specifically on their application for remediation of industrial effluent and sewage-containing municipal and household effluent. The relationships between the physicochemical characteristics of the sand grains (size, size distribution, shape, chemical composition) and the hydraulic conductivity of the sand employed in BSFs are critically discussed in relationship to the achievable loading rates and hydraulic retention times. The modes of operation and influence of the functional microbial biomass as well as biodegradable and recalcitrant particulates on these parameters is comprehensively reviewed. Finally, the bioremediation of sewage-based and industrial wastewater is examined. This includes an account of the biotic and abiotic removal mechanisms and the limitat... [more]
Dynamic Reserve Calculation Method of Fractured-Vuggy Reservoir Based on Modified Comprehensive Compression Coefficient
Shiwei He, Bo Chen, Feiyu Yuan, Xingyu Wang, Tengfei Wang
June 5, 2024 (v1)
Subject: Materials
Keywords: comprehensive compression coefficient, dynamic reserves, fracture-vuggy reservoir, material balance method, Tahe Oilfield
The low comprehensive compressibility coefficient characteristic of fracture-vuggy reservoirs often leads to imprecise dynamic reserve calculations. This study introduces a novel method for estimating dynamic reserves, which incorporates a modified comprehensive compressibility coefficient to enhance accuracy. This methodology has been applied to 23 wells in the Tahe Oilfield, resulting in error rates substantially lower than those associated with traditional techniques, thereby markedly enhancing the accuracy of dynamic reserve estimations. Specifically, for karst cave and fracture-vuggy reservoirs, the error rate in dynamic reserve calculations is reduced to under 10%, surpassing conventional methods by more than fivefold. In the case of fractured reservoirs, despite minor fluctuations in error rates due to stress sensitivity, diversion capacity, and channel variations, the proposed method still demonstrates a significant reduction in error rates compared to standard practices.
Thermodynamically Efficient, Low-Emission Gas-to-Wire for Carbon Dioxide-Rich Natural Gas: Exhaust Gas Recycle and Rankine Cycle Intensifications
Israel Bernardo S. Poblete, José Luiz de Medeiros, Ofélia de Queiroz F. Araújo
June 5, 2024 (v1)
Keywords: carbon dioxide monetization, CCS, exhaust gas recycle, gas-to-wire, multi-criteria analysis, Natural Gas, post-combustion carbon capture, Process Intensification, thermodynamic analysis
Onshore gas-to-wire is considered for 6.5 MMSm3/d of natural gas, with 44% mol carbon dioxide coming from offshore deep-water oil and gas fields. Base-case GTW-CONV is a conventional natural gas combined cycle, with a single-pressure Rankine cycle and 100% carbon dioxide emissions. The second variant, GTW-CCS, results from GTW-CONV with the addition of post-combustion aqueous monoethanolamine carbon capture, coupled to carbon dioxide dispatch to enhance oil recovery. Despite investment and power penalties, GTW-CCS generates both environmental and economic benefits due to carbon dioxide’s monetization for enhanced oil production. The third variant, GTW-CCS-EGR, adds two intensification layers over GTW-CCS, as follows: exhaust gas recycle and a triple-pressure Rankine cycle. Exhaust gas recycle is a beneficial intensification for carbon capture, bringing a 60% flue gas reduction (reduces column’s diameters) and a more than 100% increase in flue gas carbon dioxide content (increases drivi... [more]
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