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Showing records 151 to 175 of 1817. [First] Page: 3 4 5 6 7 8 9 10 11 Last
Catalytic Biomass Transformation to Hydrocarbons under Supercritical Conditions over Nickel Supported on Schungite
Elena O. Schipanskaya, Antonina A. Stepacheva, Mariia E. Markova, Alexey V. Bykov, Alexander I. Sidorov, Valentina G. Matveeva, Mikhail G. Sulman, Lioubov Kiwi-Minsker
August 23, 2024 (v1)
Keywords: deoxygenation, green diesel, Ni-catalyst, schungite support, stearic acid
Liquid fuel production from biomass-derived molecules has received great attention due to the diminished fossil fuel reserves, growing energy demand, and the necessity of CO2 emission reduction. The deoxygenation of oils and fatty acids is a promising process to obtain “green” diesel. Herein, we report the results of the study of the deoxygenation of stearic acid to alkanes as a model reaction. Series of Ni-supported on schungite were obtained by precipitation in subcritical water (hydrothermal deposition) and for comparison via wetness impregnation followed, in both cases, by calcination at 500 °C and a reduction in H2 at 300 °C. The catalyst obtained via hydrothermal synthesis showed a three-fold higher specific surface area with a four-fold higher active phase dispersion compared to the catalysts synthesized via conventional impregnation. The catalysts were tested in stearic acid deoxygenation in supercritical n-hexane as the solvent. Under optimized process conditions (temperature... [more]
Development and Characterization of a Novel Microwave Plasma Source for Enhanced Healing in Wound Treatment
Todor Bogdanov, Maria Simeonova, Lubomir Traikov, Todor Hikov, Andrey Petrov, Dimitar Peychinov, Dimitar Bakalov, Zafer Sabit, Radka Tafradjiiska-Hadjiolova, Rene Mileva
August 23, 2024 (v1)
Subject: Biosystems
Keywords: argon plasma, cold atmospheric plasma, microwave plasma, microwave plasma, plasma device, tissue regeneration, wound care, wound healing, wound regeneration
Our study explores the potential of a novel microwave plasma source for enhancing wound healing in BALB-C mouse models. Chronic wounds, particularly in diabetic individuals, present significant challenges due to impaired regenerative capacity. Cold Atmospheric Plasma (CAP) has emerged as a promising approach, offering diverse therapeutic benefits. However, its specific efficacy in the context of diabetic wounds remains underexplored. We developed and characterized a microwave plasma source optimized for wound treatment, inducing acute wounds and treating them with CAP in a controlled experimental setup. The treated group exhibited accelerated wound closure compared to controls, suggesting CAP’s potential to enhance the healing process. Our findings underscore CAP’s multifaceted impact on the wound healing cascade, highlighting its ability to promote angiogenesis, modulate inflammatory responses, and exhibit antimicrobial properties. These results position CAP as a promising interventio... [more]
Application of Principal Component Analysis for the Elucidation of Operational Features for Pervaporation Desalination Performance of PVA-Based TFC Membrane
Hamdi Chaouk, Emil Obeid, Jalal Halwani, Jack Arayro, Rabih Mezher, Semaan Amine, Eddie Gazo Hanna, Omar Mouhtady, Khaled Younes
August 23, 2024 (v1)
Keywords: operational features, pervaporation desalination, principal component analysis, PVA-based TFC membrane
Principal Component Analysis (PCA) serves as a valuable tool for analyzing membrane processes, offering insights into complex datasets, identifying crucial factors influencing membrane performance, aiding in design and optimization, and facilitating monitoring and fault diagnosis. In this study, PCA is applied to understand operational features affecting pervaporation desalination performance of PVA-based TFC membranes. PCA-biplot representation reveals that the first two principal components (PCs) accounted for 62.34% of the total variance, with normalized permeation with selective layer thickness (Pnorm), water permeation flux (P), and operational temperature (T) contributing significantly to PC1, while salt rejection dominates PC2. Membrane clustering indicates distinct influences, with membranes grouped based on correlation with operational factors. Excluding outliers increases total variance to 74.15%, showing altered membrane arrangements. Interestingly, the adopted strategy show... [more]
Effect of Nozzle Quantity on the Flow Field Characteristics and Grinding Efficiency in a Steam Jet Mill
Shenglong Huang, Yulu Zhang, Xixi Yin, Mingxing Zhang, Hong Li, Zhe Wang, Haiyan Chen, Huan Wang
August 23, 2024 (v1)
Keywords: fly ash, grinding efficiency, nozzle quantity, numerical simulation, steam jet mill
A steam jet mill (SJM), which employs industrial waste heat steam as a gas source, is a widely utilized apparatus for the pulverization of fly ash. To achieve elevated single-machine grinding capacity, efficiency improvement research based on structural optimization should be conducted. In this study, numerical simulations and industrial experiments are carried out on SJMs equipped with three and six nozzles (hereinafter referred to as N3 and N6, respectively) to study the influence of nozzle quantity on the flow field and grinding efficiency. The numerical simulation results indicate that, under the N3 structure, particles can achieve a higher impact velocity in the comminution area and improve the kinetic energy of a single impact. In the conveying area, the airflow diffusion is better, resulting in an upward flow field that is more uniform. The classification area shows an increase in the uniformity of the flow field and a significant reduction in the local vortex structure, which i... [more]
Productivity Model Study of Water-Bearing Tight Gas Reservoirs Considering Micro- to Nano-Scale Effects
Feifei Chen, Yonggang Duan, Kun Wang
August 23, 2024 (v1)
Keywords: fractal theory, micro- and nano-effects, productivity, relative gas–water permeability, tight sandstone
Tight sandstone is rich in micron- and nano-scale pores, making the two-phase flow of gas and water complex. Establishing reliable relative permeability and productivity models is an urgent issue. In this study, we first used a slip model to correct the gas phase’s no-slip Hagen−Poiseuille equation for nano- and micropores. Then, combined with the fractal theory of porous media and the tortuous capillary bundle model, we established two-phase relative permeability models for nanopores and micropores. These relative permeability models comprehensively consider the gas slippage effect, the initiation pressure gradient, the pores’ fractal characteristics, and water film mechanisms. Based on these models, we developed a three-region coupling productivity model for water-bearing tight gas reservoirs with multi-stage fractured horizontal wells. This productivity model considered the micro- and nano-scale effects and the heterogeneity of fracture networks. Then, the model was solved and valid... [more]
Morphological and Structural Characterization of Encapsulated Arginine Systems for Dietary Inclusion in Ruminants
Germán Contreras-López, Simón Morales-Rodríguez, Alfredo R. Vilchis-Néstor, Ana L. Rentería-Monterrubio, Agustín Corral-Luna, Ivan A. García-Galicia, Luis M. Carrillo-López
August 23, 2024 (v1)
Subject: Materials
Keywords: arginine, carnauba wax, encapsulation, Eudragit®, in vitro degradability, microcapsules, microcrystals, rumen
This research evaluated two methods of arginine encapsulation, melt emulsification and nanoprecipitation, using a lipid matrix of carnauba wax and commercial polymers (Eudragit®) as a protective material. The ratios of wax−arginine were 1:1, 2:1, 3:1, and 4:1, while those of Eudragit® RS:RL were 30:70 and 40:60 in proportions of 1:0.5 and 1:1 Eudragit®−arginine. The microcapsules were morphostructurally characterized by scanning electron microscopy, and a microelement analysis was performed via energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Additionally, in vitro digestibility was used to determine the protection efficiency. Both encapsulated systems presented regular (crystals) and spherical (microcapsules) polyhedral morphologies. Qualitative nitrogen decreased significantly as the wax ratio increased in the wax−arginine formulations. The formulations with a 1:1 Eudragit:−arginine ratio (1000 mg arginine) produced a higher nitrogen content in the en... [more]
Special Issue: Biochemical Processes for Sustainability
Francisco J. Hernández-Fernández, Antonia Pérez de los Ríos
August 23, 2024 (v1)
Currently, we are faced with the need to develop solution that are sustainable in terms of the energy and material resources used, which implies environmental sustainability [...]
Key Takeaways on the Cost-Effective Production of Cellulosic Sugars at Large Scale
Richa Arora, Cristiano E. Rodrigues Reis, Anuj K. Chandel
August 23, 2024 (v1)
Subject: Materials
Keywords: biorefinery, cellulosic sugar, enzymatic hydrolysis, lignocellulosic biomass, pretreatment
The production of cellulosic sugars in lignocellulose biorefinery presents significant economic and environmental challenges due to the recalcitrant nature of biomass. The economic and facile production of renewable sugars with high yield and productivity is pivotal for the success of biorefinery. The cellulosic sugars are valorized either by biochemical routes or chemical routes or by hybrid (biological and chemical) routes into renewable chemicals, fuels, and materials. This manuscript focuses on the critical parameters affecting the economic viability of cellulosic sugar production at large scale, including biomass-specific pretreatment strategies and enzyme cost efficiency. High pretreatment costs, carbohydrate loss, and inhibitors production during pretreatment are identified as major contributors to overall production costs. To address these issues, we highlight the importance of developing cost-effective and efficient pretreatment methods tailored to specific biomass types and s... [more]
Study of Low-Temperature Energy Consumption Optimization of Battery Electric Vehicle Air Conditioning Systems Considering Blower Efficiency
Dezheng Zhang, Jimin Ni, Xiuyong Shi
August 23, 2024 (v1)
Keywords: air conditioning system, battery electric vehicle, blower, low-temperature energy consumption, PTC heater, total power consumption
Battery electric vehicle (BEV) air conditioning systems often use positive temperature coefficient (PTC) heaters to heat the passenger compartment. The heating process consumes a lot of energy in low-temperature environments, which seriously affects the driving range and user experience. This study aims to reduce the low-temperature energy consumption of the air conditioning system and improve energy efficiency through an innovative optimization method. In this study, the energy consumption composition of the air conditioning system was analyzed, and the goal of minimizing the sum of the total power consumption of the PTC heater and the blower was determined, while the efficiency characteristic of the blower was considered at the same time. The relationship between the average temperature of the passenger compartment measurement points and the PTC power and airflow rate was studied by combining experiments and numerical simulations, and the alternative operating conditions that met the... [more]
Numerical Simulation of Fishtail Biomimetic Groove for Dry Gas Seals
Bowen Cui, Xuexing Ding, Shipeng Wang, Lanxia Zhang, Boyou Chen, Baoyi Wu, Bo Wang
August 23, 2024 (v1)
Keywords: biomimetic design, carp-tail groove, dry gas seal, numerical simulation, seal performance
In recent years, the use of dry gas seal technology in high-end industrial applications has become increasingly widespread. Existing research has primarily focused on unidirectional grooves. This study introduces an innovative approach by incorporating bidirectional grooves inspired by the biomimetic design of a carp tail, aiming to enhance sealing performance. The analysis of flow-field characteristics was conducted using Fluent software to evaluate the effect of different groove designs on sealing efficacy. The results indicate that curved grooves are more effective in directing gas flow and reducing fluid dynamic losses, thus improving the overall sealing efficiency. In particular, the outer-curved carp-tail groove exhibited superior dynamic pressure effects and reduced pressure drops across various operating conditions. The optimal radial dam-to-groove width ratio ranged from 3.8 to 4.1, and the optimal groove depth ranged from 6.5 to 9.6 μm. This investigation focused on the desig... [more]
Research on Intelligent Scheduling Strategy for Electric Heavy Trucks Considering Photovoltaic Outputs
Jiaheng Jing, Meiheriayi Mutailipu, Qi Wang, Qiang Xiong, Mingyao Huang, Jiuming Zhang
August 23, 2024 (v1)
Keywords: electric heavy trucks, intelligent scheduling strategy, photovoltaic output, photovoltaic storage charging station, sensitivity analysis
Due to the extensive use of fossil fuels, energy conservation and sustainable transportation have become hot topics. Electric vehicles (EVs), renowned for their clean and eco-friendly attributes, have garnered considerable global attention and are progressively being embraced worldwide. However, disorganized EV charging not only reduces charging station efficiency but also threatens power grid stability. In this low-carbon era, photovoltaic storage charging stations offer a solution that accommodates future EV growth. However, due to the significant instability in both the charging load and photovoltaic power generation within charging stations, it is critical to maximize local photovoltaic power consumption and minimize the impact of disorganized EV charging on the power grid. This paper formulates an intelligent scheduling strategy for electric heavy trucks within charging stations based on typical photovoltaic output data. The study focuses on a photovoltaic storage charging station... [more]
Double-Closed-Loop Model Predictive Control Based on a Linear Induction Motor
Shuhang Ma, Jinghong Zhao, Yiyong Xiong, Guangpu Ran, Xing Yao
August 23, 2024 (v1)
Keywords: linear induction motor, model predictive current control, model predictive speed control
The conventional PI control, which has been extensively employed in the high-performance control of linear induction motors, has the benefit of a straightforward concept, quick dynamic response, and simple control. Nevertheless, the linear induction motor is more susceptible to outside disturbances and mismatched parameters since it is a highly linked, high-order, nonlinear, time-varying, complex system. Because of this, this paper proposes a double-closed-loop control of the linear induction motor, whose speed and current loops are the model-predictive speed controller and the model-predictive current controller, respectively, to solve the problems of speed overshoot and oscillation when the linear induction motor is operated under PI control. The findings demonstrate the benefits of the suggested control strategy, which significantly enhances the linear induction motor’s speed control performance. These benefits include improved dynamic performance, limited overshooting, and robust r... [more]
Three-Dimensional Physical Test Study on the Overburden Breaking Behavior of Non-Penetrating Pre-Splitting in Small-Coal-Pillar Roadway Roofs
Shixing Cheng, Zhanguo Ma, Wenhui He, Xiao Zhang, Shiye Li, Chao Yang, Pengfei Liang
August 23, 2024 (v1)
Keywords: apparent resistivity change rate, electromagnetic wave propagation, non-penetrating pre-splitting, small coal pillar, three-dimensional physical test
In longwall coal mining, significant deformation of small-pillar roadways presents challenges for the safe and efficient retreat of mining panels. Non-penetrating directional pre-splitting alters the roof structure of these roadways and effectively manages their stability under high stress during mining operations. In this study, a three-dimensional experimental model for the non-penetrating pre-splitting of small-coal-pillar roadway roofs was established, the apparent resistivity change in the rock layer during mining of the working face was determined, the propagation law of high-frequency electromagnetic waves in the overlying rock was studied, and the stress distribution law of the surrounding rock was investigated. After non-penetrating pre-splitting in the roof, the apparent resistivity change rate of the overlying rock increased and the electromagnetic waveform exhibited scattering and diffraction, forming a short cantilever beam. After mining, the stress in the adjacent mining... [more]
A Promising Biocontrol Agent of Bacillus velezensis VC3 against Magnaporthe oryzae and Colletotrichum gloeosporioides in Plants
Kui Li, Xin Zhang, Yue Chen, Tong Zhang, Qianlong Sun, Hongtao Wu, Zhen Chen, Yan Sun, Dehua Liu, Xinqiu Tan
August 23, 2024 (v1)
Subject: Biosystems
Keywords: antifungal activity, Bacillus velezensis, biocontrol, phytopathogenic fungi, secondary metabolites
Fungal diseases of plants are one of the key factors causing global crop losses. In this study, we isolated a Bacillus velezensis strain VC3, which was found to have a broad-spectrum inhibitory effect on a variety of phytopathogenic fungi through in vitro and in planta experiments, especially on Magnaporthe oryzae and Colletotrichum gloeosporioides. Further genomic and transcriptomic analyses revealed that the B. velezensis VC3 has multiple functional gene clusters encoding for the synthesis of a variety of antifungal secondary metabolites, including antimicrobial peptides (AMPs) and lipopeptides (LPs). In addition, AMPs and LPs were isolated and purified from B. velezensis VC3 fermentation broth and their antifungal activities were verified in this study. AMPs and LPs significantly inhibited spore germination, appressorium formation, and disease development, and AMPs have a better potential for controlling M. oryzae and C. gloeosporioides than LPs. These findings open new avenues for... [more]
A Review of the Utilization of CO2 as a Cushion Gas in Underground Natural Gas Storage
Siyu Du, Mingxing Bai, Yukai Shi, Yuan Zha, Deng Yan
August 23, 2024 (v1)
Keywords: cushion gas, influencing factor, mixing degree, underground natural gas storage
A cushion gas is an indispensable and the most expensive part of underground natural gas storage. Using CO2 injection to provide a cushion gas, not only can the investment in natural gas storage construction be reduced but the greenhouse effect can also be reduced. Currently, the related research about the mechanism and laws of CO2 as a cushion gas in gas storage is not sufficient. Consequently, the difference in the physical properties of CO2 and CH4, and the mixing factors between CO2 and natural gas, including the geological conditions and injection−production parameters, are comprehensively discussed. Additionally, the impact of CO2 as a cushion gas on the reservoir stability and gas storage capacity is also analyzed by comparing the current research findings. The difference in the viscosity, density, and compressibility factor between CO2 and CH4 ensures a low degree of mixing between CO2 and natural gas underground, thereby improving the recovery of CH4 in the operation process o... [more]
The Research on Microwave Drying Characteristics of Polyethylene Terephthalate Materials Based on Frequency and Power Tuning Technology
Chongwei Liao, Zhongqi He, Rong Tang, Weixin Zhang, Changjun Liu, Chuanlong Wang
August 23, 2024 (v1)
Subject: Materials
Keywords: COVT, frequency and power tuning, heating uniformity, logistic model, microwave heating effect, MR, permittivity, PET, R-square
Polyethylene Terephthalate (PET), renowned for its exceptional physical and chemical properties, finds widespread use in our daily lives. However, conventional PET drying methods are time consuming and energy intensive. Leveraging microwave heating effects, we investigated drying characteristics concerning both microwave parameters and PET permittivity. The PET permittivity variation during heating is related to the microwave reflection at the incident port. Our innovative approach involves frequency and power tuning based on reflection. This method not only significantly improved heating uniformity and reduced temperature covariance (COVT) but also led to a more uniformly distributed temperature profile and a drastic reduction in energy consumption. Integrating precise and rapid frequency tuning, we compared our method’s efficiency with traditional approaches, revealing an impressive time savings of 2 h and an energy consumption limited to approximately less than 3 kWh/kg. Notably, ou... [more]
Decoding the Effect of Synthesis Factors on Morphology of Nanomaterials: A Case Study to Identify and Optimize Experimental Conditions for Silver Nanowires
Aryan Najjari, Mary Namisnak, Massimo McCormick, Dongping Du, Yuncheng Du
August 23, 2024 (v1)
Subject: Materials
Keywords: automated image analysis, silver nanowires, successive nanomaterial synthesis, ultralong nanowires
Silver nanowires (AgNWs) are one kind of nanomaterials for various applications such as solar panel cells and biosensors. However, the morphology of AgNWs, particularly their length and diameter, plays a critical role in determining the efficiency of energy storage systems and the transmittance of biosensors. Thus, it is imperative to study synthesis strategy for morphology control. This study focuses on synthesizing AgNWs through the solvothermal approach and aims to understand the individual and combined effects of three nucleants, NaCl, Fe(NO3)3 and NaBr, on the morphology of AgNWs. Using a modified successive multistep growth (SMG) approach and fine-tuning the nucleant concentrations, this study synthesized AgNWs with controllable aspect ratios, while minimizing the presence of undesirable byproducts like nanoparticles. Our results demonstrated the successful synthesis of AgNWs with favorable morphologies, including lengths of approximately 180 µm and diameters of 40 nm, thus resul... [more]
Analytical Solution for Contaminant Transport through a Soil−Bentonite (SB)/Geosynthetic Clay Liner (GCL)/Soil−Bentonite (SB) Composite Cutoff Wall and an Aquifer
Ming-Qing Peng, Zhi-Chao Qiu, Zhang-Long Chen, Hui Xu, Si-Liang Shen, Jia-Jie Zhou
August 23, 2024 (v1)
Subject: Optimization
Keywords: advection, analytical solution, composite cutoff wall (CCW), contaminant transport, GCL
This study develops a one-dimensional analytical solution for contaminant advection, diffusion and adsorption through a soil−bentonite (SB)/geosynthetic clay liner (GCL)/SB−aquifer composite cutoff wall (CCW) system. The solution agrees well with an existing double-layer model. Adopting toluene as a representative contaminant, using the present solution, the analysis systematically investigates the impact of hydraulic gradient (i) and the hydraulic conductivities of GCL (kgcl) and SB (ksb). The results show the following: (1) Increasing i from 0.1 to 1 reduces the concentration breakthrough time (tcb) from 20 to 11 years and mass flux breakthrough time (tfb) from infinite to 11 years, indicating lower i significantly extend both tcb and tfb, which is crucial for optimizing CCW barrier performance; (2) lowering kgcl from 5.0 × 10−11 m/s to 1 × 10−12 m/s and reducing ksb from 1.0 × 10−9 m/s to 1.0 × 10−11 m/s, would increase the tcb by 36% and 100%, respectively. It demonstrates that red... [more]
Towards Sustainable Lithium-Ion Battery Recycling: Advancements in Circular Hydrometallurgy
Maria del Mar Cerrillo-Gonzalez, Maria Villen-Guzman, Carlos Vereda-Alonso, Jose Miguel Rodriguez-Maroto, Juan Manuel Paz-Garcia
August 23, 2024 (v1)
Subject: Environment
Keywords: circular economy, circular hydrometallurgy, Li-ion battery recycling, metal separation
The growing demand for lithium-ion batteries (LIBs) has led to significant environmental and resource challenges, such as the toxicity of LIBs’ waste, which pose severe environmental and health risks, and the criticality of some of their components. Efficient recycling processes are essential to mitigate these issues, promoting the recovery of valuable materials and reducing environmental pollution. This review explores the application of electrodialysis in the process of recycling LIBs to contribute to the principles of circular hydrometallurgy. The article is structured to provide a comprehensive understanding of the topic, starting with an overview of the environmental and resource challenges associated with manufacturing LIBs. Then the current recycling processes are presented, focusing on hydrometallurgical methods. The concept of circular hydrometallurgy is introduced, emphasizing sustainable resource recovery. The electrodialysis technique is described in this context, highlight... [more]
Fault Diagnosis Method of Bearings Based on SCSSA-VMD-MCKD
Qing Lv, Kang Zhang, Xiancong Wu, Qiang Li
August 23, 2024 (v1)
Keywords: fault diagnosis, Maximum Correlated Kurtosis Deconvolution, rolling bearings, Sparrow Search Algorithm, Variational Mode Decomposition
To tackle the issue of detecting early, subtle faults in rolling bearings in the presence of noise interference, the SCSSA-VMD-MCKD method is suggested. This method optimizes the Variational Mode Decomposition (VMD) and Maximum Correlated Kurtosis Deconvolution (MCKD) by integrating the sine-cosine and Cauchy Mutation Sparrow Search Algorithm (SCSSA). The approach aims to effectively diagnose faults in rolling bearings by leveraging the strengths of VMD and MCKD in noise reduction and highlighting fault frequencies. The method utilizes the SCSSA algorithm to autonomously search for parameters in both VMD and MCKD, using the EnvelopeCrest Factor Ec as a fitness function. Firstly, SCSSA is employed to optimize the decomposition mode number K and penalty factor α in the VMD algorithm. Secondly, the parameters in the MCKD algorithm are optimized, and MCKD is used for deconvolution to enhance the impulsive characteristics of the best modal component. Finally, the signal is further analyzed... [more]
Research on an Adaptive Active Suspension Leveling Control Method for Special Vehicles
Pan Zhang, Huijun Yue, Pengchao Zhang, Jie Gu, Hongjun Yu
August 23, 2024 (v1)
Keywords: active suspension, automatic leveling, gyroscope, hydraulic cylinders, Kalman filtering, PID
Adaptive active suspension systems, integral to specialized vehicles, hold significance for their stability and safety. This study introduces a novel adaptive active suspension system featuring four independently controlled wheels employing wheel-hub motors, hydraulic cylinders, pump motor power, controllers, and sensors. A rapid and, within a certain range, leveling and height adjustment control strategy is proposed for this system, utilizing the Kalman filter algorithm. Additionally, the paper examines the front-wheel Ackermann steering model and four-wheel reverse Ackermann transition model to enhance the suspension’s stability. Subsequently, experiments on leveling and height adjustment are conducted, demonstrating the system’s capability to swiftly and accurately rectify the vehicle’s deviation angle within the specified threshold. Following adjustments made by the leveling and height control algorithm, the vehicle body promptly returns to the preset level state and designated hei... [more]
3D Printer Nozzle Structure Form Optimal Structural Analysis
Yun Yu, Gen Zhang, Qiming Xiao, Anping Ji, Yueqiang Feng, Guangyao Zhu, Lang Zhou
August 23, 2024 (v1)
Subject: Materials
Keywords: 3D printing, COMSOL simulation, FDM technology, nozzle structure, orthogonal test
The most representative technology of 3D printing is fused deposition modeling (FDM). To improve the printing accuracy of FDM technology, this paper first takes the outlet diameter, angle of convergence, and rectifier section length of the nozzle as the influencing factors. It takes the melt outlet speed stability, viscosity, and outlet pressure as the indexes to design the orthogonal test. Then, COMSOL Multiphysics fluid−solid coupling simulation was used to simulate and analyze the structural characteristics of the 3D printer nozzle, and the range analysis method was used to analyze the data. Finally, the two-phase flow combination was used to simulate the morphological characteristics of the melt flowing out of the nozzle. The results show that the simulation results of the two materials are similar. As the nozzle diameter decreases, the melt pressure decreases, the velocity increases, and the viscosity decreases. For PLA wire rods, the optimal structure of the nozzle is that the ou... [more]
Sustainable Sludge Management in China: Quantifying GHG Emissions and Exploring Its Reduction Strategies
Dongming Hu, Peng Jiang, Yipei Chen, Fuyan Gao, Shuai Liu
August 23, 2024 (v1)
Subject: Environment
Keywords: emission reduction, greenhouse gas emission, life-cycle assessment, Renewable and Sustainable Energy, sludge management
This study aims to evaluate the emissions of greenhouse gases (GHGs) stemming from the sludge treatment sector in China and to investigate the feasibility of novel technologies in curtailing these emissions, with the aim of fostering sustainable sludge management methodologies. Employing a life-cycle assessment (LCA) methodology, the research computed the comprehensive GHG emissions resulting from sludge treatment, taking into consideration diverse elements such as treatment techniques (e.g., landfills, incineration, and land application) and the geographical variations among China’s 660 municipalities. Findings indicate that the total amount of GHG emissions from sludge treatment amounted to 18.54 Mt CO2-eq in 2017, with incineration registering the highest emissions (10,011.53 kg CO2-eq/t dry sludge (DS)), followed by landfills (717.51 kg CO2-eq/t DS) and land application (276.41 kg CO2-eq/t DS). The geographical dispersion of emissions characteristics reveal notable regional dispari... [more]
Impacts of CO2-CH4 Mixed Gas on Property of Formation Oil from the Bohai Oilfield
Renfeng Yang, Lijun Zhang, Xianhong Tan, Xiaofeng Tian, Xugang Yang, Xiaohan Shu, Guodong Zou, Erlong Yang, Changdong Jiang, Shaobin Hu
August 23, 2024 (v1)
Keywords: CH4 reinjection, experimental study, mixed gas, oil flooding by CO2, property of formation oil
Mechanism analysis and technical scheme optimization on CO2 displacement and CO2 storage are based on the high-pressure physical properties of CO2-added formation oil. Oil and natural gas samples from the BZ25-1 block in the Bohai oilfield were used to conduct high-pressure physical property experiments to explore the impacts of CO2-CH4 mixed gas on the properties of formation oil. After injecting different amounts of mixed gas, the saturated pressure was measured by constant mass expansion test, the viscosity was measured by falling ball method, the expansion coefficient was measured by gas injection expansion test, and the gas−oil ratio and volume coefficient were obtained by single degassing test. The results show that with gas injection, the saturation pressure and dissolved gas−oil ratio of formation oil increase, the volume coefficient and expansion factor go up, while the oil viscosity reduces. With the increase in gas addition, the properties of formation oil continue to improv... [more]
Wavelet Cross-Correlation Signal Processing for Two-Phase Flow Control System in Oil Well Production
Dmitry Arseniev, Galina Malykhina, Dmitry Kratirov
August 23, 2024 (v1)
Keywords: cross-correlation, oil production process, radioisotope measuring transducer, wavelet transform
An algorithm based on continuous measurement of multiphase flows of oil well production has been designed to improve the efficiency of the technical control of oil production processes in the field. Separation-free, non-contact measurement of multiphase flows of oil well products allows increasing the efficiency of managing oil production processes in the field. Monitoring the current density using radioisotope measuring transducers (RMTs) allows obtaining information about the structure of the flow in the form of the distribution of gas inclusions and the speed of movement of liquid and gas in a two-phase flow. Fluid velocity measurement is based on digital processing of RMT signals, applying a continuous or discrete undecimated wavelet transform to them, and assessing the cross-correlation of wavelet coefficients in individual subspaces of the wavelet decomposition. The cross-correlation coefficients of two RMT signals located at a base distance, calculated in the subspaces of the wa... [more]
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