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Network-Constrained Unit Commitment with Flexible Temporal Resolution

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arXiv

arXiv 2024年

作者： Yu, Zekuan Zhong, Haiwang Ruan, Guangchun Yan, Xinfei The State Key Laboratory of Power System Operation and Control Dept. of Electrical Engineering Tsinghua University Beijing China The Sichuan Energy Internet Research Institute Tsinghua University China The Lab for Information & Decision Systems Massachusetts Institute of Technology Massachusetts United States

Modern network-constrained unit commitment (NCUC) bears a heavy computational burden due to the ever-growing model scale. This situation becomes more challenging when detailed operational characteristics, complicated constraints, and multiple objectives are considered. We propose a novel simplification method to determine the flexible temporal resolution for acceleration and near-optimal solutions. The flexible temporal resolution is determined by analyzing the impact on generators in each adaptive time period with awareness of congestion effects. Additionally, multiple improvements are employed on the existing NCUC model compatible with flexible temporal resolution to reduce the number of integer variables while preserving the original features. A case study using the IEEE 118-bus and the Polish 2736-bus systems verifies that the proposed method achieves substantial acceleration with low cost variation and high accuracy. Copyright © 2024, The Authors. All rights reserved.

关键词： Energy management

Modulating Surface Electron Strucuture of Lamno3 Nanocatalysts for Peroxymonosulfate Activation by Quenching-Induced Near-Surface Modification

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SSRN 2023年

作者： Xu, Aihua Chen, Runshi Zhao, Wenpei Lin, Jiajin Hu, Rongrong Khan, Aimal Li, Xiaoxia Zhao, Shuaiqi Qiu, Yongcai School of Chemistry and Chemical Engineering Wuhan Textile University Wuhan430200 China Hubei Key Laboratory of Biomass Fibers and Eco-Dyeing & Finishing Wuhan Textile University Wuhan430200 China School of Environment and Energy State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control South China University of Technology Guangdong Guangzhou510000 China

Modifying the surface structure of catalysts is critical for facilitating peroxymonosulfate (PMS) activation. Here, we present a quenching approach to effectively modify the surface chemistry of LaMnO3 nanocatalysts, in which the optimal catalyst obtained by quenching displays higher catalytic degradation performance for levofloxacin (LEVO). The comprehensive characterization demonstrates that the increased intrinsic catalytic activity is directly connected to the quenching-induced exposed facets transition and synergistic effect of Cu/Co ions. Meanwhile, density functional theory calculations (DFT) further reveal the aforementioned modifications to surface structure result in an upward shift of d-band centre, which optimizes the adsorption of PMS and makes it easier for the transfer of electron between Mn sites and PMS, thereby facilitating the reduction of Mn4+ and enhancing catalytic activity for PMS activation and LEVO degradation. This study presents new ideas for controlling surface structure of perovskite metal oxide catalysts and broadens applicability of quenching chemistry in heterogeneous catalysis. © 2023, The Authors. All rights reserved.

关键词： Lanthanum compounds

Rapid modeling of transient processes in hydrogen-blended natural gas pipelines featuring injection and withdrawal points

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International Journal of Hydrogen Energy 2025年

作者： Gong, Junhua Zhou, Chaoqun Wang, Yanxin Deng, Yajun Chen, Yujie Wang, Peng Yu, Bo Chen, Bin Yu, Zhipeng Wang, Bohong School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing102617 China Changqing Oil and Gas Transportation Branch of Northwest Company of PipeChina Xingqing District Ningxia Yinchuan City750004 China PipeChina Engineering Technology Innovation Co.Ltd Tianjin300450 China School of Petroleum Engineering Yangtze University Wuhan430100 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National & Local Joint Engineering Research Center of Harbor Oil & Gas Storage and Transportation Technology/Zhejiang Key Laboratory of Pollution Control for Port-Petrochemical Industry Zhejiang Ocean University Zhoushan316022 China

Blending hydrogen into natural gas pipelines enables the large-scale delivery and application of hydrogen, contributing to carbon emission reduction and promoting the transition to cleaner energy sources. Accurate and efficient predictions of transient processes in such pipelines are critical for effective management and operation. This study proposes a Fourier Neural Operator (FNO)-based model for the rapid prediction of transient processes in hydrogen-blended pipelines with injection and withdrawal points. The model is trained using numerical simulation data of pressure and flow dynamics, with initial conditions, boundary conditions, and the hydrogen blending ratio as inputs to predict hydraulic parameters along the pipeline over time. By optimizing data preprocessing and neural network hyperparameters, the model achieves high accuracy and efficiency in predicting hydraulic states. The FNO model achieves average Root Mean Squared Errors (RMSEs) of 1.06 × 10−3, 1.64 × 10−3, and 7.40 × 10−4 for pressure, flow rate, and density, respectively, with the Coefficient of Determination (R2) exceeding 0.99 for all three variables. Furthermore, the model demonstrates strong generalization capabilities, accurately predicting hydraulic states for pipeline topologies and scenarios beyond the training data. In these cases, the RMSE remains in the order of 10−3 or smaller. For a 100 km pipeline, the computational efficiency of the FNO model is at least 969 times higher than that of traditional numerical methods, with the maximum efficiency improvement reaching 5168 times as the number of pipeline cases simultaneously predicted increases. These results highlight the potential of the FNO model for real-time applications in hydrogen-blended natural gas pipeline management. © 2025 Hydrogen Energy Publications LLC

关键词： Mean square error

Health Risk Evaluation and Value Loss Analysis of Pm2.5 and Ozone in China

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SSRN 2024年

作者： Wang, Bingbing Ji, Yaqin Yang, Xiawei Shi, Jingwen Xu, Wenju Ma, Jiaofan Shen, Ruixing Wang, Baoqing Zhang, Jing Feng, Yinchang College of Environmental Science and Engineering Nankai University Tianjin300350 China State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control Tianjin300350 China Tianjin Eco-Environmental Monitoring Center Tianjin300191 China

In recent years, increasing concern has been observed in China regarding PM2.5 and ozone as major atmospheric pollutants, which pose significant risks to air quality and public health. The aim of this study was to analyze the spatial and temporal distribution patterns of PM2.5 and O3 across 31 provinces in China during 2022. Furthermore, the study assessed the population’s exposure risks and estimated the loss of health value. The findings indicated that (1) The PM2.5 concentration followed a monthly "U" pattern, while the O3 concentration exhibited an inverted "U" trend. The simultaneous presence of PM2.5 and O3 was primarily noted in spring. In contrast, PM2.5-dominated and ozone-dominated pollution were more prevalent in winter and summer, respectively. (2) The risk of public exposure to them displayed a spatially parallel distribution, with higher risks generally found east of the Heihe-Tengchong Line compared to the west. (3) An estimated 31.99 × 104 individuals were projected to suffer premature mortality, with 22.58 × 104 and 9.41 × 104 linked to PM2.5 and ozone, respectively. The economic costs associated with premature deaths due to them were 214.31 billion and 94.53 billion yuan, respectively, representing 7.53% of GDP. These results underscored the significant impact of PM2.5 and ozone pollution on public health and the loss of health value in China. Therefore, the urgent implementation of targeted pollution control and prevention strategies for air pollution across different provinces is necessary. © 2024, The Authors. All rights reserved.

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Editorial: Characterization and application of magneto-sensitive soft materials

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Frontiers in Materials 2023年 10卷

作者： Zhang, Zhili Li, Decai Yu, Miao Niu, Xiaodong Li, Weihua Institute of Magnetic Fluids School of Mechanical Electronic and Control Engineering Beijing Jiaotong University Beijing China State Key Laboratory of Tribology Tsinghua University Beijing China Key Laboratory for Optoelectronic Technology and Systems Ministry of Education College of Optoelectronic Engineering Chongqing University Chongqing China Department of Mechanical Engineering College of Engineering Shantou University Shantou China School of Mechanical Materials Mechatronic and Biomedical Engineering University of Wollongong WollongongNSW Australia

Magnetic fluids are nanocolloids made up of nanometer-sized ferromagnetic particles dispersing in a carrier liquid (typically comprises three parts: base carrier liquid, surfactant, and ferromagnetic particles). Since the particles are easier to agglomerate, ferromagnetic particles are typically coated with surfactants to prevent agglomeration. Magnetic nanoparticles are uniformly disseminated in the carrier liquid with the assistance of surfactants, which play a crucial role in the magnetic fluid composition. Li et al. systematically studied the coating state and colloidal stability of oleic acid (OA) and 3-(N,N-Dimethylmyristylammonio) propanesulfonate (DP) coated magnetite nanoparticles in the polar and apolar carrier liquid. The total Gibbs interfacial energy was analyzed based on Van Oss-Chaudhry-Good and DLVO theory to describe the behaviors of coated particles in solvents. Zang et al. studied the effect of different fatty acids as surfactants on the rheological properties of magnetic fluids. The results showed that the mixed fatty acids showed greater viscosity growth and a greater slope of the viscosity growth curve than the magnetic fluids dispersed with a single acid. This indicates that the mixed fatty acids have more stable rheological properties. The viscousity-temperature performance of kerosene-base magnetic fluids at low temperatures can be improved by adjusting the ratio of mixed fatty acids. The most typical application of magnetic liquids is sealing, which has the outstanding advantages of zero leakage, long life and low resistance. Magnetic fluid seals as a class of non-contact sealing technology have been a research focus. In order to solve the problem of the pole shoes in the ferrofluid seal are easily damaged under the situation of the large radial beating of the main shaft. Liu et al. proposed a new structure of the ferrofluid seal that use a redial-changed ring magnet as the magnetic source. Considering that the ring magnets have problems o

关键词： magnetic fluids (MF) magnetorheological fluids (MRF) magneto-sensitive soft materials non-contact sealing torsional vibration damper intelligent material energy absorber

Experimental Study on Mass Loss Mechanism and Cooling Effect of Compressed Air Foam on Fuel Surface at Different Temperatures

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SSRN 2023年

作者： Tian, Fengyuan Fang, Jun Fang, Lulu Shah, Hassan Raza Lang, Xuqing Tian, Zhijian Tang, Fei State Key Laboratory of Fire Science University of Science and Technology of China Anhui Hefei230026 China State Key Laboratory of Safety and Control for Chemicals SINOPEC Research Institute of Safety Engineering Co. Ltd. Shandong Qingdao266100 China XCMG Fire-Fighting Safety Equipment Co. Ltd. Jiangsu Xuzhou221100 China

Compressed air foam (CAF) has been widely used as a high-performance extinguishing agent for liquid fuel fire. In this work, the effects of initial fuel surface temperatures (50-80°C) on the drainage and evaporation of CAF were studied experimentally. It was found that as time goes on, the drain rate first increases with the increase of initial fuel surface temperature, and then decreases with the increase of the temperature. But at the same foam mass, the drain rate of the foam is positively correlated to the initial fuel surface temperature. Furthermore, the drainage and evaporation of the foam with ER =5.5 is less affected by the fuel surface temperature than ER =10. Then the cooling effect of the foam was studied. The fuel layer temperature variation could be roughly divided into three stages: rapid decline, relatively stable and gradual rise, which may be related to the foam drainage. But in the rapid decline state, the decrease in fuel temperature is mainly related to the heat transfer between the fuel and foam, rather than drainage. In addition, for the foam with ER =10, the rising stage starts earlier. This work improves the understanding of mass loss and suppression mechanisms of fire-extinguishing foams. © 2023, The Authors. All rights reserved.

关键词： Evaporation

Microstructure and mechanical properties of friction stir welded powder metallurgy AA2024 alloy

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Journal of Central South University 2022年第3期29卷 871-882页

作者： HAN Wei-hao LI Pei LIU Nan CHEN Cun-guang DONG Shi-peng GUO Zhi-meng YANG Fang SUI Yan-li VOLINSKYAlex A Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Beijing Engineering Research Center of High Purity Metal Sputtering Target Beijing 102200China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Innovation Group of Marine Engineering Materials and Corrosion Control Southern Marine Science and EngineeringGuangdong Laboratory(Zhuhai)Zhuhai 519082China Department of Mechanical Engineering University of South FloridaTampaFlorida 33620USA

The extruded plate of powder metallurgy AA2024 aluminum alloy was successfully solid-state joined by friction stir welding(FSW) to demonstrate potential applications in the aerospace and automotive industries. For determining the optimal processing parameters of FSW, the microstructure, mechanical properties, and fracture behavior of FSW joints were evaluated. When the processing parameters were optimized with 2000 r/min rotation speed and100 mm/min traverse speed, high quality welds were achieved. The ultimate tensile strength yield strength and elongation of the joint can reach 415 MPa(85% of the base metal strength), 282 MPa, and 9.5%, respectively. The hardness of the joint gradually decreased from the alloy matrix to the heat-affected zone. The lowest strength and hardness appeared near the heat-affected zone because of the over-aging caused by heat flow from repeated stirring during FSW. The average grain size of the stir zone(2.15 μm) was smaller than that of the base metal(4.43 μm) and the heat-affected zone(5.03 μm), whose grains had <110> preferred orientation.

关键词： high-strength aluminum alloy powder metallurgy AA2024 alloy friction stir welding mechanical properties

Numerical and Experimental Research on Electromagnetic-Thermal and Leakage Defects Characteristics of the High Voltage Cable Terminal

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SSRN 2023年

作者： Liu, Xingmou Gu, Yan Li, Lei Yang, Yongming Cheng, Peng Jadoon, Ammad Chongqing Key Laboratory of Complex Systems and Bionic Control Chongqing University of Posts and Telecommunications Chongqing400065 China State Key Laboratory of Power Transmission Equipment & System Security and New Technology School of Electrical Engineering Chongqing University Chongqing400044 China State Grid Sichuan Electric Power Company Chengdu Power Supply Company Chengdu610000 China NFC-Institute of Engineering &Technology Multan Pakistan

Thermal and insulation performance of the High Voltage Cable Terminal (HVCT) could effectively improve the reliability and economy of power energy transmission. In this paper, a numerical model of the electromagnetic heat flow field was proposed to analyze the heat transfer and temperature characteristics of HVCT under oil leakage defects. This model was the first validated using operation data from the actual equipment and the relative error was less than 1.51%. The effects of oil leakage fault on the global and local temperature distribution of the HVCT were then investigated under different load currents. In addition, the local temperature rise effect of different ambient temperatures on the HVCT oil leakage defect was also considered. Finally, combined with reference indicators such as oil level, temperature, and temperature gradient, a qualitative and quantitative evaluation of the oil leakage fault of HVCT was performed. The results showed that the temperature of the core, surface, and their maximum temperature gradient were linearly related to the ambient temperature. However, the temperature of the core at the oil leak exceeded the normal temperature by up to 7.2 °C with 1000A load current, and the temperature gradient change reaches 681.3 °C/m, which indicated that the convection heat dissipation effect of the oil-deficient part was poor, and the heat accumulates near the cable core. Therefore, the numerical model and analytical results presented in this paper provided an important method for online temperature monitoring and fault analysis of HVCTs. © 2023, The Authors. All rights reserved.

关键词： Thermal gradients

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中国碳收支:1980~2021年

Science Bulletin 2024年第1期69卷 114-124页

作者：夏晓圣任培阳王旭辉刘丹陈修治丹利何斌何洪林居为民梁敏琪陆星劼彭静覃章才夏江周郑博魏静乐旭于贵瑞朴世龙袁文平 School of Atmospheric Sciences Guangdong Province Data Center of Terrestrial and Marine Ecosystems Carbon CycleSun Yat-sen UniversityZhuhai 510245China Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking UniversityBeijing 100091China State Key Laboratory of Tibetan Plateau Earth System Resources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Earth Surface Processes and Resource Ecology College of Global Change and Earth System ScienceBeijing Normal UniversityBeijing 100875China Synthesis Research Center of China’s Ecosystem Research Network Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China International Institute for Earth System Science Nanjing UniversityNanjing 210023China Tianjin Key Laboratory of Water Resources and Environment Tianjin Normal UniversityTianjin 300387China Institute of Environment and Ecology Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China

As one of the world's largest emitters of greenhouse gases,China has set itself the ambitious goal of achieving carbon peaking and carbon ***,it is crucial to quantify the magnitude and trend of sources and sinks of atmospheric carbon dioxide(CO_(2)),and to monitor China's progress toward these *** state-of-the-art datasets and models,this study comprehensively estimated the anthropogenic CO_(2)emissions from energy,industrial processes and product use,and waste along with natural sources and sinks of CO_(2)for all of China during *** recognize the differences among various methods of estimating greenhouse emissions,the estimates are compared with China's National Greenhouse Gas Inventories(NGHGIs)for 1994,2005,2010,2012,and *** CO_(2)emissions in China have increased by 7.39 times from 1980 to 12.77 Gt CO_(2)a^(-1)in *** benefiting from ecological projects(e.g.,Three Norths Shelter Forest System Project),the land carbon sink in China has reached 1.65 Gt CO_(2)a^(-1)averaged through 2010-2021,which is almost 15.81 times that of the carbon sink in the *** average,China's terrestrial ecosystems offset 14.69%±2.49%of anthropogenic CO_(2)emissions through *** provincial-level administrative regions of China,Xizang and Qinghai,have achieved carbon neutrality according to our estimates,but nearly half of the administrative regions of China have terrestrial carbon sink offsets of less than 10%of anthropogenic CO_(2)*** study indicated a high level of consistency between NGHGIs and various datasets used for estimating fossil CO_(2)emissions,but found notable differences for land carbon *** estimates of the terrestrial carbon sinks of NGHGIs urgently need to be verified with process-based models which integrate the comprehensive carbon cycle processes.

关键词： CO_(2)emission Land carbon sink China Carbon neutrality Carbon budget