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Investigations of Water Flow Behaviors Induced by Local Temperature Variations through a Single Rough Fracture for the Enhanced Geothermal Systems

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Journal of Thermal Science 2024年第3期33卷 1055-1064页

作者： li jiawei YE lin Department of Energy and Power Engineering Tsinghua UniversityBeijing100084China School of Power and Energy Northwestern Polytechnical UniversityXi’an710072China

In recent years,Enhanced Geothermal System(EGS)technologies have been applied to the geothermal resources production in the Hot Dry Rock(HDR).The core of EGS technologies is to adopt hydraulic fracturing in the reservoir to create a connected network of discrete fractures with the consideration of water as a working fluid for hydraulic fracturing and heat production.This paper investigates the characteristics of water flow behaviors through a single rough fracture under different temperature and pressure conditions.A single fracture model with rough fracture surfaces is constructed and then characterized,and influences of the anisotropic factor on the average tortuosity and frictional resistance coefficient of water flow through a single fracture with rough surfaces have been compared and analyzed.With consideration of other impacting factors(temperature,pressure,fracture roughness),the impact of mass flow rate has also been presented.Numerical simulation results present that changes of average tortuosity for water flow through a single rough facture are mainly affected by temperature.It can be observed that higher temperature leads to larger average tortuosity but the frictional resistance coefficient shows an opposite trend.As for pressure conditions,it is found that effects of pressure on average tortuosity and frictional resistance coefficient is very small,which can be neglected under high pressure conditions.Furthermore,the average tortuosity shows a progressively linear relationship with the mass flow rate.On the contrary,the frictional resistance coefficient has a negative relationship with the mass flow rate.It is revealed that when the mass flow rate reaches a critical point,the influences of temperature on the frictional resistance coefficient will be negligible.Comparisons of single rough fractures with different anisotropic factors show that values of average tortuosity and frictional resistance coefficient have positive relationships with the increase of anisotropic factors.

关键词： single rough fracture tortuosity frictional resistance enhanced geothermal system

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VOC emitted by biopharmaceutical industries:Source profiles,health risks,and secondary pollution

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Journal of Environmental Sciences 2024年第1期135卷 570-584页

作者： jiawei Ma lin li State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China National Engineering Laboratory for VOCs Pollution Control Material&Technology University of Chinese Academy of SciencesBeijing 101408China

The biopharmaceutical industry contributes substantially to volatile organic compounds(VOCs)emissions,causing growing concerns and social developmental conflicts.This study conducted an on-site investigation of the process-based emission of VOCs from three biopharmaceutical enterprises.In the workshops of the three enterprises,26 VOCs were detected,which could be sorted into 4 classes:hydrocarbons,aromatic hydrocarbons,oxygen-containing compounds,and nitrogen-containing compounds.Ketones were the main components of waste gases,accounting for 44.13%-77.85%of the overall VOCs.Process-based source profiles were compiled for each process unit,with the fermentation and extraction units of tiamulin fumarate being the main source of VOC emissions.Dimethyl heptanone,vinyl acetate,diethylamine,propylene glycol methyl ether(PGME),and benzene were screened as priority pollutants through a fuzzy comprehensive evaluation system.Ground level concentration simulation results of the Gauss plume diffusion model demonstrated that the diffusivity of VOCs in the atmosphere was relatively high,indicating potential non-carcinogenic and carcinogenic risks 1.5-2 km downwind.Furthermore,the process-based formation potentials of ozone and secondary organic aerosols(SOAs)were determined and indicated that N-methyl-2-pyrrolidone,dimethyl heptanone,and PGME should be preferentially controlled to reduce the ozone formation potential,whereas the control of benzene and chlorobenzene should be prioritized to reduce the generation of SOAs.Our results provide a basis for understanding the characteristics of VOC emission by biopharmaceutical industries and their diffusion,potentially allowing the development of measures to reduce health risks and secondary pollution.

关键词： Biopharmaceutical Volatile organic compound Priority pollutant Exposure risk Secondary pollution

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Theoretical Analysis of Cooperative Driving at Idealized Unsignalized Intersections

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Tsinghua Science and Technology 2024年第1期29卷 257-270页

作者： Shen li jiawei Zhang Zhenwu Chen li li Department of Civil Engineering Tsinghua UniversityBeijing 100084China Department of Automation Tsinghua UniversityBeijing 100084China Shenzhen Urban Transport Planning Center Co. Ltd.Shenzhen 518000China

Cooperative driving is widely viewed as a promising method to better utilize limited road resources and alleviate traffic congestion.In recent years,several cooperative driving approaches for idealized traffic scenarios(i.e.,uniform vehicle arrivals,lengths,and speeds)have been proposed.However,theoretical analyses and comparisons of these approaches are lacking.In this study,we propose a unified group-by-group zipper-style movement model to describe different approaches synthetically and evaluate their performance.We derive the maximum throughput for cooperative driving plans of idealized unsignalized intersections and discuss how to minimize the delay of vehicles.The obtained conclusions shed light on future cooperative driving studies.

关键词： cooperative driving connected and automated vehicles unsignalized intersection

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Sludge composition and characteristics shaped microbial community and further determined process performance: A study on full-scale thermal hydrolysis-anaerobic digestion processes

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Journal of Environmental Sciences 2024年第3期137卷 96-107页

作者： Wei liu Chenxiang Sun Wei li Tianle li Zhan Chen jiawei Wang Zhengran Ren Xianghua Wen School of Environment Tsinghua UniversityBeijing 100084China Jinneng Holding Group DatongShanxi 037000China Research and Development Center Beijing Drainage Group Co.Ltd.Beijing 100124China Beijing Dabeinong Science and Technology Group Co. Ltd.Beijing 100080China

Anaerobic digestion (AD) with thermal hydrolysis (TH) pretreatment is a promising process for excess sludge treatment,while there lacks of the knowledge from full-scale process about the impact of sludge composition and characteristics on microbial community and performance.The sludge physiochemical indices,microbial community and performance data of four full-scale TH-AD plants were characterized,and their relationships was elucidated.The four plants were operated under almost similar total organic loading rate (OLR)but their methanogenesis performance differentiate into two groups,namely superior group(SupG) and the inferior group (Inf G).In both groups,TH effectively solubilized particulate organic compounds,meanwhile raised the ammonia nitrogen (NH_(4)^(+)-N) and volatile fatty acid (VFA) concentration.Compared with the Sup G,thermal hydrolyzed sludge of Inf G had higher level of VFAs,NH_(4)^(+)-N and total chemical oxygen demand (t COD),which showed higher inhibition effect on microbes,leading to a community with lower diversity,lower abundance of carbohydrate degrading functional guild,higher protein degrading one,and methanogens that adapted to limited substrates,and further declined the methane production rate.Thus,it was recommended that OLR alone was not sufficient for controlling the system in design and operation,the concentration of VFAs,NH_(4)^(+)-N and t COD should be equally considered.Their higher concentration,together with the higher abundance of Defluviitoga and Proteiniphilum were recommended as indicators for inferior running condition.Our results proposed that microbial communities played a role of bridge between environmental factors and performance,provided implications for engineering ecology and operational regulation for full-scale sludge TH-AD process.

关键词： Thermal hydrolysis Anaerobic digestion Microbial community Full-scale

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Present-day Upper-crustal Strain Rate Field in Southeastern Tibet and its Geodynamic Implications:Constraints from GPS Measurements with ABIC Method

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 265-275页

作者： YANG Shaohua PAN jiawei li Haibing SHI Yaolin Key Laboratory of Continental Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Jiangsu Donghai Continental Deep Hole Crustal Activity National Observation and Research Station DonghaiJiangsu 222300China Key Laboratory of Computational Geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China

The Earth’s surface kinematics and deformation are fundamental to understanding crustal evolution.An effective research approach is to estimate regional motion field and deformation fields based on modern geodetic networks.If the discrete observed velocity field is obtained,the velocity related fields,such as dilatation rate and maximum shear strain rate,can be estimated by applying varied mathematical approaches.This study applied Akaike's Bayesian Information Criterion(ABIC)method to calculate strain rate fields constrained by GPS observations in the southeast Tibetan Plateau.Comparison with results derived from other three methods revealed that our ABIC-derived strain rate fields were more precise.The maximum shear strain rate highlighted the Xianshuihe–Xiaojiang fault system as the main boundary for the outward migration of material in southeastern Tibet,indicating rotation of eastern Tibet material around the eastern Himalaya rather than whole extrusion along a fixed channel.Additionally,distinct dilatation rate patterns in the northeast and southwest regions of the fault system were observed.The northeast region,represented by the Longmenshan area,exhibited negative dilatational anomalies;while the southwest region,represented by the Jinsha River area north of 29°N,displayed positive dilatational anomalies.This indicates compression in the former and extension in the latter.Combined with deep geophysical observations,we believe that the upper and lower crusts of the Jinsha River area north of 29°N are in an entire expanding state,probably caused by the escape-drag effect of material.The presence of a large,low-viscosity region south of 29°N may not enable the entire escape of the crust,but instead result in a differential escape of the lower crust faster than the upper crust.

关键词： strain rate differential escape ABIC GPS southeastern Tibet

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High corrosion and wear resistant electroless Ni–P gradient coatings on aviation aluminum alloy parts

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 155-164页

作者： Bo Wang jiawei li Zhihui Xie Gengjie Wang Gang Yu College of Chemistry and Chemical Engineering Hunan UniversityChangsha 410012China Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province/College of Chemistry and Chemical Engineering China West Normal UniversityNanchong 637002China Zhongchuan Machinery Ltd.Co. Aero Engine Corporation of ChinaChangsha 410200China

A Ni–P alloy gradient coating consisting of multiple electroless Ni–P layers with various phosphorus contents was prepared on the aviation aluminum alloy. Several characterization and electrochemical techniques were used to characterize the different Ni–P coatings’ morphologies, phase structures, elemental compositions, and corrosion protection. The gradient coating showed good adhesion and high corrosion and wear resistance, enabling the application of aluminum alloy in harsh environments. The results showed that the double zinc immersion was vital in obtaining excellent adhesion (81.2 N). The optimal coating was not peeled and shredded even after bending tests with angles higher than 90°and was not corroded visually after 500 h of neutral salt spray test at 35℃. The high corrosion resistance was attributed to the misaligning of these micro defects in the three different nickel alloy layers and the amorphous structure of the high P content in the outer layer. These findings guide the exploration of functional gradient coatings that meet the high application requirement of aluminum alloy parts in complicated and harsh aviation environments.

关键词： aluminum alloy electroless nickel coating corrosion adhesion

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Bioactive citrate-based polyurethane tissue adhesive for fast sealing and promoted wound healing

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Regenerative Biomaterials 2024年第1期3卷 69-81页

作者： Yan li jiawei liu Chenxi lian He Yang Mingjiang Zhang Youfa Wang Honglian Dai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Biomedical Materials and Engineering Research Center of Hubei ProvinceWuhan University of TechnologyWuhan 430070China Chaozhou Branch of Chemistry and Chemical Engineering Guangdong Laboratory Chaozhou 521000China Shenzhen Research Institute of Wuhan University of Technology Shenzhen 518000China

As a superior alternative to sutures,tissue adhesives have been developed significantly in recent years.However,existing tissue adhesives struggle to form fast and stable adhesion between tissue interfaces,bond weakly in wet environments and lack bioactivity.In this study,a degradable and bioactive citrate-based polyurethane adhesive is constructed to achieve rapid and strong tissue adhesion.The hydrophobic layer was created with polycaprolactone to overcome the bonding failure between tissue and adhesion layer in wet environments,which can effectively improve the wet bonding strength.This citrate-based polyurethane adhesive provides rapid,non-invasive,liquid-tight and seamless closure of skin incisions,overcoming the limitations of sutures and commercial tissue adhesives.In addition,it exhibits biocompatibility,biodegradability and hemostatic properties.The degradation product citrate could promote the process of angiogenesis and accelerate wound healing.This study provides a novel approach to the development of a fast-adhering wet tissue adhesive and provides a valuable contribution to the development of polyurethane-based tissue adhesives.

关键词： tissue adhesive polyurethane citrate wet adhesion

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Experimental Investigation and X-Ray Computed Microtomography Simulation on Thermal Physical Properties of Foundation Materials after Molten Salt Leakage in the Storage Tank

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Journal of Thermal Science 2024年第2期33卷 591-601页

作者： WANG Zhaowen ZHOU Hao LUO jiawei li Yawei FANG Hao liU Tianxiao State Key Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringZhejiang UniversityHangzhou310027China

This paper studied the thermal physical properties of foundation materials in the molten salt tank of thermal energy storage system after molten salt leakage by Transient plane source experiment and X-ray computed microtomography simulation methods.The microstructure,thermal properties and pressure resistance with different particle diameters were addressed.The measured heat conductivities from Transient plane source experiment for three cases are 0.49 W/(m·K),0.48 W/(m·K),and 0.51 W/(m·K),and the porosity is 30.1%,30.7%,and 31.2% respectively.The heat conductivity simulating results of three cases are 0.471 W/(m·K),0.482W/(m·K),and 0.513 W/(m·K).The ratio of difference between the results of simulation and Transient plane source measurement is as low as 1.2%,verifying the reliability of experimental and simulation results to a certain degree.Compared with the heat conductivity of 0.097-0.129 W/(m·K) and porosity of 71.6%-78.9% without leaking salt,the porosity is reduced by more than 50% while the heat conductivity increased by 4 to 5 times after molten salt leakage.This significant increase in heat conductivity has a great impact on security operation,structure design,and modeling of the tank foundation for solar power plants.

关键词： heat conductivity X-ray computed microtomography foundation materials three-phase threshold algorithm molten salt leakage

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A Multi-AGV Routing Planning Method Based on Deep Reinforcement Learning and Recurrent Neural Network

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1720-1722页

作者： Yishuai lin Gang Hu liang Wang Qingshan li jiawei Zhu the School of Computer Science and Technology Xidian UniversityXi’an 710000China Suzhou Mingyi Intelligence Warehousing Information Technology Co. Ltd.Kunshan 215300China the School of Information Engineering Chang’an UniversityXi’an 710000China

Dear Editor,This letter presents a multi-automated guided vehicles(AGV) routing planning method based on deep reinforcement learning(DRL)and recurrent neural network(RNN), specifically utilizing proximal policy optimi... 详细信息

关键词： network AGV Deep

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Dynamic Equivalent Modeling for Black-box Microgrids Under Multi-operating-point by Using LSTM

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 639-648页

作者： Yunlu li Josep M.Guerrero Junyou Yang Yajuan Guan Guiqing Ma jiawei Feng School of Electrical Engineering Shenyang University of TechnologyShenyang 110819China Department of Energy Technology Center for Research on Microgrids(CROM)Aalborg University9220 Aalborg EastDenmark

Since the high penetration of distributed energy sources complicates the dynamics of electrical power systems,accurate dynamic models are indispensable for study on the transient behavior of the microgrid(MG).In some practices,the lack of full detailed information results in failure of dif-ferential equation based dynamic modeling,which leads to a demand for a black-box MG modeling method.It is a critical challenge to maintain the effectiveness of the black-box model under a wide operating range and various fault conditions.In this paper,inspired by the mathematical equivalence between the recurrent neural network(RNN)and differential-algebraic equations(DAEs),a dynamic equivalent modeling method,using long short-term memory(LSTM),is presented to tackle this challenge.At first,the modeling equivalence and advantages of our basic idea are explained.Then,modeling procedures,including data preparation and design guidelines,are presented.Finally,the proposed method is applied to a multi-microgrid testing system for performance evaluation.The results,under various scenarios,reveal that the proposed modeling method has an adequate capability for representing the dynamic behaviors of a black-box MG under grid fault and operating point changing conditions.Index Terms-Deep learning,dynamic behavior,dynamic equivalent model,microgrid,neural network.

关键词： Deep learning dynamic behavior dynamic equivalent model microgrid neural network

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