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Model reduction of fractional impedance spectra for time–frequency analysis of batteries, fuel cells, and supercapacitors

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Carbon Energy 2024年第1期6卷 108-141页

作者： Weiheng Li Qiu-An Huang yuxuan bai Jia Wang Linlin Wang Yuyu Liu Yufeng Zhao Xifei Li Jiujun Zhang Institute for Sustainable Energy/College of Sciences Shanghai UniversityShanghaiChina Shanxi Key Laboratory of Nanomaterials and Nanotechnology School of Mechanical and Electrical EngineeringXi'an University of Architecture and TechnologyXi'anShaanxiChina Xi'an Key Laboratory of New Energy Materials and Devices School of Materials Science and EngineeringInstitute of Advanced Electrochemical EnergyXi'an University of TechnologyXi'anShaanxiChina

Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and *** increase the reliability of time–frequency analysis,a theoretical correlation between frequency-domain stationary analysis and time-domain transient analysis is urgently *** present work formularizes a thorough model reduction of fractional impedance spectra for electrochemical energy devices involving not only the model reduction from fractional-order models to integer-order models and from high-to low-order RC circuits but also insight into the evolution of the characteristic time constants during the whole reduction *** following work has been carried out:(i)the model-reduction theory is addressed for typical Warburg elements and RC circuits based on the continued fraction expansion theory and the response error minimization technique,respectively;(ii)the order effect on the model reduction of typical Warburg elements is quantitatively evaluated by time–frequency analysis;(iii)the results of time–frequency analysis are confirmed to be useful to determine the reduction order in terms of the kinetic information needed to be captured;and(iv)the results of time–frequency analysis are validated for the model reduction of fractional impedance spectra for lithium-ion batteries,supercapacitors,and solid oxide fuel *** turn,the numerical validation has demonstrated the powerful function of the joint time–frequency *** thorough model reduction of fractional impedance spectra addressed in the present work not only clarifies the relationship between time-domain transient analysis and frequency-domain stationary analysis but also enhances the reliability of the joint time–frequency analysis for electrochemical energy devices.

关键词： battery,fuel cell,supercapacitor fractional impedance spectroscopy model reduction time-frequency analysis

Permafrost carbon cycle and its dynamics on the Tibetan Plateau

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Science China Life Sciences 2024年第9期67卷 1833-1848页

作者： Leiyi Chen Guibiao Yang yuxuan bai Jinfeng Chang Shuqi Qin Futing Liu Mei He Yutong Song Fan Zhang Josep Pe?uelas Biao Zhu Guoying Zhou Yuanhe Yang Key Laboratory of Tibetan Medicine Research Chinese Academy of Sciences State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences China National Botanical Garden College of Environmental and Resource Sciences Zhejiang University Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration Ecology and Nature Conservation Institute Chinese Academy of Forestry University of Chinese Academy of Sciences Consejo Superior de Investigaciones Científicas (CSIC) Global Ecology Unit CREAF-CSIC-UAB (Universitat Autònoma de Barcelona) Centre for Ecological Research and Forestry (CREAF) Institute of Ecology College of Urban and Environmental Sciences and Key Laboratory for Earth Surface Processes of the Ministry of Education Peking University Northwest Institute of Plateau Biology Chinese Academy of Sciences

Our knowledge on permafrost carbon(C) cycle is crucial for understanding its feedback to climate warming and developing nature-based solutions for mitigating climate change. To understand the characteristics of permafrost C cycle on the Tibetan Plateau, the largest alpine permafrost region around the world, we summarized recent advances including the stocks and fluxes of permafrost C and their responses to thawing, and depicted permafrost C dynamics within this century. We find that this alpine permafrost region stores approximately 14.1 Pg(1 Pg=1015g) of soil organic C(SOC) in the top 3 m. Both substantial gaseous emissions and lateral C transport occur across this permafrost region. Moreover, the mobilization of frozen C is expedited by permafrost thaw, especially by the formation of thermokarst landscapes,which could release significant amounts of C into the atmosphere and surrounding water bodies. This alpine permafrost region nevertheless remains an important C sink, and its capacity to sequester C will continue to increase by 2100. For future perspectives, we would suggest developing long-term in situ observation networks of C stocks and fluxes with improved temporal and spatial coverage, and exploring the mechanisms underlying the response of ecosystem C cycle to permafrost thaw. In addition, it is essential to improve the projection of permafrost C dynamics through in-depth model-data fusion on the Tibetan Plateau.

关键词： permafrost carbon climate change carbon release carbon sink permafrost thaw thermokarst formation

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2001—2022年西藏地区旱柳物候期变化及其影响因素

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生态学杂志 2024年第6期43卷 1587-1595页

作者：杜军黄志诚索朗塔杰白宇轩王挺西藏高原大气环境科学研究所/西藏高原大气环境开放实验室西藏拉萨850001 中国气象局墨脱大气水分循环综合观测野外科学试验基地/墨脱国家气候观象台西藏墨脱860700 西藏自治区气象信息网络中心拉萨850001 西藏林芝市气象局西藏林芝860000

为了揭示西藏高原温带植物旱柳的物候对气候变化响应的时空格局,利用2001—2022年泽当、日喀则和林芝3个观测站旱柳物候期数据(叶芽膨大期(LED)、展叶始期(LUD)、开花始期(FFD)、叶变色末期(LCD)和落叶末期(LFD)),以及逐日平均气温(T_(... 详细信息

为了揭示西藏高原温带植物旱柳的物候对气候变化响应的时空格局,利用2001—2022年泽当、日喀则和林芝3个观测站旱柳物候期数据(叶芽膨大期(LED)、展叶始期(LUD)、开花始期(FFD)、叶变色末期(LCD)和落叶末期(LFD)),以及逐日平均气温(T_(m))、最高气温(T_(max))、最低气温(T_(min))、气温日较差(TDR)、相对湿度(RH)、降水量(P_(r))、日照时数(S)和≥0℃积温(∑T_(0))等资料,采用线性回归、Pearson相关系数和逐步回归等方法进行了分析。结果表明:(1)空间上,西藏地区旱柳春季物候期(LED、LUD、FFD)林芝最早、日喀则最迟,秋季物候期(LCD、LFD)相反;生长季长度(LOS)为238~268 d,以林芝最大、日喀则最小。(2)时间尺度上,2001—2022年泽当、日喀则旱柳各物候期均呈推迟趋势,林芝旱柳秋季物候期趋于推迟;林芝和日喀则旱柳LOS显著延长,分别为11.90和6.12 d·10 a^(-1),泽当旱柳LOS缩短(-4.50 d·10 a^(-1))。(3)旱柳生长季内T_(m)呈上升趋势,T_(max)、T_(min)趋势各不相同;泽当和日喀则TDR变大、P_(r)减少、S增加,林芝正好相反;林芝和日喀则∑T0显著增加,泽当∑T0明显减少。(4)对春季物候期影响最大的气象因子以气温为主,降水仅对泽当、林芝旱柳LCD以及泽当LFD的影响最大;季风指数(MI)只与泽当站旱柳LED、FFD呈显著相关,其他2站物候期相关性不显著;7月MI与T_(m)、P_(r)、S均存在显著的相关性,8月MI与S也有显著的负相关关系,这些气象因子虽不是影响物候期的主要因子,也会起到间接作用。

关键词：旱柳物候变化气象因子季风西藏

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联合时频分析:以单孔中电荷穿透深度和电流空间分布为例

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电化学（中英文） 2024年第2期30卷 1-22页

作者：王南黄秋安李伟恒白玉轩张久俊上海大学理学院/可持续能源研究院上海200444

近年来,联合时频分析再次成为研究热点。超级电容器功率密度高和寿命长,但为了优化平衡功率密度和能量密度,需考虑两个关键因素:(1)多孔基质的比表面积;(2)孔内空间电解质可抵达性。本文采用联合时频分析方法,研究孔内电荷穿透深度及电... 详细信息

近年来,联合时频分析再次成为研究热点。超级电容器功率密度高和寿命长,但为了优化平衡功率密度和能量密度,需考虑两个关键因素:(1)多孔基质的比表面积;(2)孔内空间电解质可抵达性。本文采用联合时频分析方法,研究孔内电荷穿透深度及电流空间分布。具体开展了如下工作:(i)在复正弦电流激励下,推导单孔的时域响应和频域响应解析解,由此定义了描述电荷扩散行为的时频特征。(ii)采用联合时频方法,分析了内部参数和外部参数对孔内电荷穿透率的影响,揭示了孔内电荷有限扩散和无限扩散之间的演变规律。(iii)基于穿透率临界值,定义了孔内部参数的临界值,由此判断孔内电荷半无限扩散和有限扩散。本文提出联合时频分析方法,实现了多孔电极中复杂物理化学过程的信息融合,联合时频分析最终殊途同归,并提高诊断可靠性。

关键词：联合时频分析单孔电荷穿透深度电流空间分布半无限扩散有限长度扩散

Simple construction of the α-MnO2@ZIF-8 nanomaterial with highly enhanced U(Ⅵ) adsorption performance and assessed removal mechanism

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Progress in Natural Science:Materials International 2023年第4期33卷 508-517页

作者： Siyi Wang yuxuan bai Zhixiong Zhang Chengde Xie Wenhui Song Chen Wang Zhuoyu Ji Jianjun Wang North China Electric Power University MOE Key Laboratory of Resources and Environmental Systems Optimization College of Environmental Science and Engineering

In this study, the one-dimensional nanomaterial α-MnO2@ZIF-8 was satisfactorily fabricated using a simple hydrothermal method by modifying ZIF-8 on α-MnO2nanowires for high-performance extraction of U(Ⅵ) out of water solution. The experimental data indicated that the adsorption of U(Ⅵ) on α-MnO2@ZIF-8 was intensely dependent on solution pH but not on ionic strength. The maximum adsorption of U(Ⅵ) on α-MnO2@ZIF-8 at pH= 5.0 and T = 298 K was 802.36 mg/g, substantially higher than the adsorption on α-MnO2(22.32 mg/g) or ZIF-8(551.31 mg/g) under the same conditions, indicating that the performance of the modified α-MnO2was greatly enhanced. Attaining adsorption equilibrium within 45 min, the analytical kinetic process of α-MnO2@ZIF-8 indicated that its adsorption on U(Ⅵ) was monolayer chemisorption. The adsorption experiments and XPS analyzed the possible adsorption mechanism of U(Ⅵ) in the reaction with α-MnO2@ZIF-8 during the adsorption process, namely intra-sphere surface complexation, chemisorption and electrostatic interaction. The simple preparation and high removal efficiency of α-MnO2@ZIF-8 indicated that this adsorbent had good prospects for application in wastewater.

关键词： α-MnO_2@ZIF-8 Adsorption Uranium Mechanism

Time-frequency analysis of Li solid-phase diffusion in spherical active particles under typical discharge modes

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Journal of Energy Chemistry 2022年第4期31卷 209-224页

作者： Qiu-An Huang yuxuan bai Liang Wang Juan Wang Fangzhou Zhang Linlin Wang Xifei Li Jiujun Zhang Institute for Sustainable Energy/College of Science Shanghai UniversityShanghai 201800China Shaanxi Key Laboratory of Nanomaterials and Nanotechnology School of Mechanical and Electrical EngineeringXi’an University of Architecture and TechnologyXi’an 710055ShaanxiChina Institute of Materials/School of Materials Science and Engineering Shanghai UniversityShanghai 200072China Xi’an Key Laboratory of New Energy Materials and Devices Institute of Advanced Electrochemical Energy&School of Materials Science and EngineeringXi’an University of TechnologyXi’anShaanxi 710048China

Li transient concentration distribution in spherical active material particles can affect the maximum power density and the safe operating regime of the electric vehicles(EVs). On one hand, the quasiexact/exact solution obtained in the time/frequency domain is time-consuming and just as a reference value for approximate solutions;on the other hand, calculation errors and application range of approximate solutions not only rely on approximate algorithms but also on discharge modes. For the purpose to track the transient dynamics for Li solid-phase diffusion in spherical active particles with a tolerable error range and for a wide applicable range, it is necessary to choose optimal approximate algorithms in terms of discharge modes and the nature of active material particles. In this study, approximation methods,such as diffusion length method, polynomial profile approximation method, Padé approximation method,pseudo steady state method, eigenfunction-based Galerkin collocation method, and separation of variables method for solving Li solid-phase diffusion in spherical active particles are compared from calculation fundamentals to algorithm implementation. Furthermore, these approximate solutions are quantitatively compared to the quasi-exact/exact solution in the time/frequency domain under typical discharge modes, i.e., start-up, slow-down, and speed-up. The results obtained from the viewpoint of time-frequency analysis offer a theoretical foundation on how to track Li transient concentration profile in spherical active particles with a high precision and for a wide application range. In turn, optimal solutions of Li solid diffusion equations for spherical active particles can improve the reliability in predicting safe operating regime and estimating maximum power for automotive batteries.

关键词： Li solid-phase diffusion Discharge mode Approximate algorithm Quasi-exact/exact solution Time-frequency analysis

Capacitive energy storage from single pore to porous electrode identified by frequency response analysis

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Journal of Energy Chemistry 2023年第2期77卷 384-405,I0010页

作者： Weiheng Li Qiu-An Huang Yu Li yuxuan bai Nan Wang Jia Wang Yongming Hu Yufeng Zhao Xifei Li Jiujun Zhang Institute for Sustainable Energy/College of Sciences Shanghai UniversityShanghai 200444China Hubei Key Laboratory of Ferro-&Piezoelectric Materials and Devices Faculty of Physics and Electronic ScienceHubei UniversityWuhan 430062HubeiChina Shaanxi Key Laboratory of Nanomaterials and Nanotechnology School of Mechanical and Electrical EngineeringXi’an University of Architecture and TechnologyXi’an 710055ShaanxiChina Xi’an Key Laboratory of New Energy Materials and Devices Institute of Advanced Electrochemical Energy&School of Materials Science and EngineeringXi’an University of TechnologyXi’an 710048ShaanxiChina

Rate capability,peak power,and energy density are of vital importance for the capacitive energy storage(CES)of electrochemical energy *** frequency response analysis(FRA)is regarded as an efficient tool in studying the *** the present work,a bi-scale impedance transmission line model(TLM)is firstly developed for a single pore to a porous *** only the TLM of the single pore is reparameterized but also the particle packing compactness is defined in the ***,the CES properties are identified by FRA,focused on rate capability *** frequency,peak power *** series resistance,and energy density *** frequency limiting capacitance for a single pore to a porous *** on these relationships,the CES properties are numerically simulated and theoretically predicted for a single pore to a porous electrode in terms of intra-particle pore length,intra-particle pore diameter,inter-particle pore diameter,electrolyte conductivity,interfacial capacitance&exponent factor,electrode thickness,electrode apparent surface area,and particle packing ***,the experimental diagnosis of four supercapacitors(SCs)with different electrode thicknesses is conducted for validating the bi-scale TLM and gaining an insight into the CES properties for a porous electrode to a single *** calculating results suggest,to some extent,the inter-particle pore plays a more critical role than the intra-particle pore in the CES properties such as the rate capability and the peak power density for a single pore to a porous ***,in order to design a better porous electrode,more attention should be given to the inter-particle pore.

关键词： Porous electrode Intra-particle pore Inter-particle pore Capacitive energy storage Electrochemical impedance spectroscopy Frequency response analysis

AP/CAP系列核电站冷态性能试验电源需求分析与措施

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电工技术 2024年第10期 25-27页

作者：张德亮段琰璞张振强白宇轩国核示范电站有限责任公司山东荣成264300

对比分析了AP/CAP系列与M310冷态性能试验差异性。基于AP/CAP系列冷态性能试验特点,从工艺系统、仪控系统电源需求出发,对电源稳定性进行了风险分析,提出了220 kV辅助电源供电下的AP/CAP系列核电厂冷态性能试验电源配置方案,以期为后续... 详细信息

对比分析了AP/CAP系列与M310冷态性能试验差异性。基于AP/CAP系列冷态性能试验特点,从工艺系统、仪控系统电源需求出发,对电源稳定性进行了风险分析,提出了220 kV辅助电源供电下的AP/CAP系列核电厂冷态性能试验电源配置方案,以期为后续相关工作提供参考与借鉴。

关键词： AP/CAP系列核电站冷态性能试验电源需求分析辅助电源

医学技术类本科生专业分流选择成因的质性研究——以天津医科大学为例

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医学教育管理 2024年第2期10卷 215-221页

作者：杜汋祁祺白宇璇陈晋妍徐雅萱汤娜李欣怡贾子婧王怡斐白琳茹天津医科大学公共卫生学院天津300070 天津医科大学眼视光学院天津300070 天津医科大学教学信息中心天津300070 天津医科大学护理学院天津300070 天津医科大学药学院天津300070 天津医科大学基础医学院天津300070 天津市第二医院科技教育处天津300141

目的明晰独立医学院校医学技术类专业本科生大类招生专业分流的选择成因,以期为高校医学技术类专业分流政策提供建议。方法选取当前就读于天津医科大学医学技术学院并参与过专业分流的本科生20名进行半结构化访谈,采用Colaizzi七步分析... 详细信息

目的明晰独立医学院校医学技术类专业本科生大类招生专业分流的选择成因,以期为高校医学技术类专业分流政策提供建议。方法选取当前就读于天津医科大学医学技术学院并参与过专业分流的本科生20名进行半结构化访谈,采用Colaizzi七步分析法,探究其在专业分流时选择专业的原因。结果参与访谈的本科生选择现就读专业的因素包括个人因素、学科因素、就业因素、他人因素。结论专业分流对学生的个人发展、素质提升和能力培养方面起到了重要作用,现行专业分流政策存在学生在专业分流时具有一定盲目性、分流前职业规划课程内容不足、专业分流缺乏灵活性、招生比例不合理等问题。针对此类问题,学校应当为参与专业分流的学生丰富职业规划课程;专业分流后学校也可以给予学生二次选择专业的机会;学校还需要对医学技术类专业的学院规模与招生比例等方面进行统筹规划。

关键词：独立医学院校医学技术大类招生专业分流质性研究