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Free radicals trigger the closure of open pores in lignin-derived hard carbons toward improved sodium-storage capacity

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Journal of Energy Chemistry 2024年第7期94卷 551-559页

作者： Wen-Jun Ji Zong-Lin Yi Ming-Xin Song Xiao-Qian Guo Yi-Lin Wang Yi-Xuan Mao Fang-Yuan su Jing-Peng Chen Xian-Xian Wei Li-Jing Xie cheng-Meng Chen CAS Key Laboratory of Carbon Materials Institute of Coal ChemistryChinese Academy of SciencesTaiyuan 030001ShanxiChina University of Chinese Academy of Sciences Beijing 100049China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China School of Environment and Safety Taiyuan University of Science and TechnologyTaiyuan 030001ShanxiChina

The chemical activation of various precursors is effective for creating additional closed pores in hard carbons for sodium storage.However,the formation mechanism of closed pores under the influence of pore-forming agents is not well understood.Herein,an effective chemical activation followed by a high-temperature self-healing strategy is employed to generate interconnected closed pores in lignin-derived hard carbon(HCs).By systematic experimental design combined with electron paramagnetic res-onance spectroscopy,it can be found that the content of free radicals in the carbon matrix influences the closure of open pores at high temperatures.Excessively high activation temperature(>700 C)leads to a low free radical concentration,making it difficult to achieve self-healing of open pores at high tempera-tures.By activation at 700°C,a balance between pore making and self-healing is achieved in the final hard carbon.A large number of free radicals triggers rapid growth and aggregation of carbon microcrys-tals,blocking pre-formed open micropores and creating additional interconnected closed pores in as-obtained hard carbons.As a result,the optimized carbon anode(LK-700-1300)delivers a high reversible capacity of 330.8 mA h g^(-1) at 0.03 A g^(-1),which is an increase of 86 mA h g^(-1) compared to the pristine lignin-derived carbon anode(L-700-1300),and exhibits a good rate performance(202.1 mA h g^(-1) at 1 A g^(-1)).This work provides a universal and effective guidance for tuning closed pores of hard carbons from otherprecursors.

关键词： Hard carbon Chemical activation Free radical Self-healing Closed pores Sodium ion batteries

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Mechanisms of fracture propagation from multi-cluster using a phase field based HMD coupling model in fractured reservoir

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Petroleum Science 2024年第3期21卷 1829-1851页

作者： Yun-Jin Wang Bo Wang Hang su Tu Chang Ren-cheng Dong Li-Zhe Li Wei-Yu Tang Ting-Xue Jiang Fu-Jian Zhou State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum-Beijing China University of Petroleum-Beijing at Karamay China National Oil and Gas Exploration and Development Corporation Ltd. University of Texas at Austin SINOPEC Research Institute of Petroleum Engineering

Natural fractures(NFs) are common in shale and tight reservoirs, where staged multi-cluster fracturing of horizontal wells is a prevalent technique for reservoir stimulation. While NFs and stress interference are recognized as significant factors affecting hydraulic fracture(HF) propagation, the combined influence of these factors remains poorly understood. To address this knowledge gap, a novel coupled hydromechanical-damage(HMD) model based on the phase field method is developed to investigate the propagation of multi-cluster HFs in fractured reservoirs. The comprehensive energy functional and control functions are established, while incorporating dynamic fluid distribution between multiple perforation clusters and refined changes in rock mechanical parameters during hydraulic fracturing. The HMD coupled multi-cluster HF propagation model investigates various scenarios, including single HF and single NF, reservoir heterogeneity, single HF and NF clusters, and multi-cluster HFs with NF clusters. The results show that the HMD coupling model can accurately capture the impact of approach angle(θ),stress difference and cementation strength on the interaction of HF and NF. The criterion of the open and cross zones is not fixed. The NF angle(a) is not a decisive parameter to discriminate the interaction.According to the relationship between approach angle(θ) and NF angle(a), the contact relationship of HF can be divided into three categories(θ = a, θ a). The connected NF can increase the complexity of HF by inducing it to form branch fracture, resulting in a fractal dimension of HF as high as2.1280 at angles of ±45°. Inter-fracture interference from the heel to the toe of HF shows the phenomenon of no, strong and weak interference. Interestingly, under the influence of NFs, distant HFs from the injection can become dominant fractures. However, as a gradually increases, inter-fracture stress interference becomes the primary factor influencing HF propagation, gradually superseding the dominance of NF induce

关键词： HMD coupling Phase field Natural fracture Flow distribution Hydraulic fracturing Inter-fracture interference

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创新政策能否提升能源效率?——来自国家创新型城市试点的经验证据

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产业经济研究 2024年第1期 1-15页

作者：赵城苏婧复旦大学经济学院上海200433 武汉大学经济与管理学院湖北武汉430072

我国已经迈入创新型国家行列,加快技术创新引领能源转型是实现“双碳”目标,继而促进经济高质量发展的迫切要求。在构建理论模型来阐述创新政策影响能源效率机理的基础上,以国家创新型城市试点为准实验,并利用多时点DID方法考察了创新... 详细信息

我国已经迈入创新型国家行列,加快技术创新引领能源转型是实现“双碳”目标,继而促进经济高质量发展的迫切要求。在构建理论模型来阐述创新政策影响能源效率机理的基础上,以国家创新型城市试点为准实验,并利用多时点DID方法考察了创新政策对城市能源效率的因果效应和作用机制。研究发现,创新政策显著提高了城市能源效率,这一结论在考虑了内生性问题和异质性处理效应后依然成立。异质性分析发现,创新政策对能源效率的促进作用仅存在于创新环境优良、产业专业化程度高、能源消耗量大以及环境规制严格的城市。机制检验发现,创新政策通过推动城市绿色技术创新、产业结构升级、人力资本集聚以及资源优化配置对能源效率产生积极的影响。研究结论对中国通过深入实施创新驱动发展战略来实现“双碳”目标和全面推进中国式现代化进程具有重要的参考价值和现实意义。

关键词：创新政策能源效率国家创新型城市多时点双重差分法异质性处理效应

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深圳市2015~2021年雨源型河流水质时空变化及其对降雨的响应

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环境科学 2024年第2期45卷 780-791页

作者：韦必颖成建梅苏晓煜程天舜中国地质大学(武汉)环境学院武汉430078 广东省深圳生态环境监测中心站深圳518049 广东省深圳市水务规划设计院深圳518001

雨源型城市河流水容量偏小,缺乏动态补充水源,易受污染.基于深圳市2015~2021年全市(不含深汕)9大流域的21个水质指标数据和逐日降雨数据,利用单因子指数评价、综合污染指数、层次聚类分析和Pearson相关分析等方法,研究深圳市河流水质时... 详细信息

雨源型城市河流水容量偏小,缺乏动态补充水源,易受污染.基于深圳市2015~2021年全市(不含深汕)9大流域的21个水质指标数据和逐日降雨数据,利用单因子指数评价、综合污染指数、层次聚类分析和Pearson相关分析等方法,研究深圳市河流水质时空分布特征及特征污染物对降雨的响应关系.结果表明:①2015年全区大部分断面水质都是劣Ⅴ类水,2018年10月后河流水质总体得到大幅度改善,与2018年深圳市开展治水专项活动背景一致,到2021年约62%的断面水质达Ⅰ~Ⅲ类水标准;②深圳市(不含深汕)西部人口稠密地区的水质污染较东部更严重,河口和支流下游水质污染较上游更严重;③深圳市坪山河、龙岗河、茅洲河和深圳河的水质受降雨的影响显著;④深圳市河流的主要特征污染指标是DO、COD、BOD5、NH_(4)^(+)-N、TP、高锰酸盐指数、石油类和阴离子表面活性剂;对于坪山河和龙岗河,降雨使TP和NH_(4)^(+)-N指标浓度升高;对于茅洲河,降雨使TP和COD指标浓度升高;对于深圳河,降雨使COD、TP和NH_(4)^(+)-N指标浓度升高.以上结果能够揭示深圳市雨源型河流水质时空变化情况及其对降雨事件引发的非点源污染的响应关系,为深圳市打造更高品质水环境提供科学参考.

关键词：水质评价雨源型河流降雨时空分布深圳市

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Geological context and vents morphology in the ultramafic-hosted Tianxiu field, Carlsberg Ridge

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Acta Oceanologica Sinica 2023年第9期42卷 62-70页

作者： Jin Liang Chunhui Tao Xiangxin Wang cheng su Wei Gao Yadong Zhou Weikun Xu Xiaohe Liu Zhongjun Ding Key Laboratory of submarine Geosciences Ministry of Natural ResourcesHangzhou 310012China Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China National Deep Sea Center Qingdao 266237China School of Earth Sciences Zhejiang UniversityHangzhou 310027China Ocean College Zhejiang UniversityZhoushan 316021China

The Tianxiu hydrothermal field(TXHF) located on Carlsberg Ridge is one of the few active ultramafic-hosted venting systems known in the Indian Ocean. Despite numerous investigations, there is limited understanding of its sulfide structure morphology, and the factors controlling the formation of TXHF are poorly understood. In this study, we conducted detailed seafloor mapping using visual data obtained by dives using the human-occupied vehicle(HOV) Jiaolong. The TXHF is found to be an active, off-axis, ultramafic-hosted, high-temperature hydrothermal area in which serpentine peridotite is exposed. Two main hydrothermal sites were identified, i.e., P and Y, both of which feature a complex of chimneys and beehive diffusers constituting a “chimney jungle” and isolated large steep-sided structures developed on flat-lying sulfide mounds. In addition, some sporadic inactive chimneys and outcrops of hydrothermal deposits were noted. The chimneys are rich in Fe and Zn sulfide, and lack the central fluid channel formed by focused high-temperature fluid flow. Hydrothermal venting at TXHF is likely related to low-angle detachment faults that focus and transport hydrothermal fluids away from a heat source along the valley wall. Our results complement and expand upon previous works concerning sulfide chimney morphology and their corresponding mineral paragenesis in ultramafic-hosted hydrothermal systems in the Indian Ocean and further our understanding of modern seafloor hydrothermal systems.

关键词： hydrothermal activity sulfide accumulation morphology ultramafic-hosted Carlsberg Ridge

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Understanding adversarial attacks on observations in deep reinforcement learning

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Science China(Information Sciences) 2024年第5期67卷 69-83页

作者： You QIAOBEN chengyang YING Xinning ZHOU Hang su Jun ZHU Bo ZHANG Department of Computer Science and Technology Beijing National Research Center for Information Science and Technology Tsinghua-Bosch Joint Center for Machine Learning Institute for Artificial Intelligence Tsinghua University Peng cheng Laboratory

Deep reinforcement learning models are vulnerable to adversarial attacks that can decrease the cumulative expected reward of a victim by manipulating its observations. Despite the efficiency of previous optimization-based methods for generating adversarial noise in supervised learning, such methods might not achieve the lowest cumulative reward since they do not generally explore the environmental dynamics.Herein, a framework is provided to better understand the existing methods by reformulating the problem of adversarial attacks on reinforcement learning in the function space. The reformulation approach adopted herein generates an optimal adversary in the function space of targeted attacks, repelling them via a generic two-stage framework. In the first stage, a deceptive policy is trained by hacking the environment and discovering a set of trajectories routing to the lowest reward or the worst-case performance. Next, the adversary misleads the victim to imitate the deceptive policy by perturbing the observations. Compared to existing approaches, it is theoretically shown that our adversary is strong under an appropriate noise level. Extensive experiments demonstrate the superiority of the proposed method in terms of efficiency and effectiveness, achieving state-of-the-art performance in both Atari and MuJoCo environments.

关键词： deep learning reinforcement learning adversarial robustness adversarial attack

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Design and prototyping of the readout electronics for the transition radiation detector in the high energy cosmic radiation detection facility

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Nuclear Science and Techniques 2024年第4期35卷 189-199页

作者： Jie-Yu Zhu Yang-Zhou su Hai-Bo Yang Fen-Hua Lu Yan Yang Xi-Wen Liu Ping Wei Shu-Cai Wan Hao-Qing Xie Xian-Qin Li Cong Dai Hui-Jun Hu Hong-Bang Liu Shu-Wen Tang cheng-Xin Zhao Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China

The high energy cosmic-radiation detection(HERD)facility is planned to launch in 2027 and scheduled to be installed on the China Space Station.It serves as a dark matter particle detector,a cosmic ray instrument,and an observatory for high-energy gamma rays.A transition radiation detector placed on one of its lateral sides serves dual purpose,(ⅰ)calibrating HERD's electromagnetic calorimeter in the TeV energy range,and(ⅱ)serving as an independent detector for high-energy gamma rays.In this paper,the prototype readout electronics design of the transition radiation detector is demonstrated,which aims to accurately measure the charge of the anodes using the SAMPA application specific integrated circuit chip.The electronic performance of the prototype system is evaluated in terms of noise,linearity,and resolution.Through the presented design,each electronic channel can achieve a dynamic range of 0–100 fC,the RMS noise level not exceeding 0.15 fC,and the integral nonlinearity wassults show that the prototype system can satisfy the requirements of the detector's scientific goals.

关键词： HERD Dark matter particle detection TRD Readout electronics SAMPA Data acquisition Performance test

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Epidemiological Study of Outpatients in Rabies Post-Exposure Prophylaxis Clinics—Tianjin Municipality,China,2020

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China CDC weekly 2021年第39期3卷 822-824页

作者： Yifang Liu Lin Li Jie Lyu cheng su Tianjin Centers for Disease Control and Prevention TianjinChina.

summary What is already known on this topic?Rabies remains a serious public health problem in China.The only way to prevent the fatal disease was through timely and adequate post-exposure prophylaxis(PEP).What is added by this report?Among all the 126,133 cases visited Tianjin PEP clinics during 2020,more than 90%of the patients were injured by domestic dogs or cats,and about 70%of the animals received vaccination.Most outpatients have knowledge of rabies and show high compatibility with PEP.

关键词： Tianjin compatibility Rabies

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面向煤矿巡检机器人的高能效路径规划方法

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煤矿安全 2024年第6期55卷 211-216页

作者：陈骋苏成杰中煤科工集团沈阳研究院有限公司煤矿安全技术国家重点实验室

针对现有矿用机器人路径路规划方法存在的效率低、收敛速度慢、易陷入局部最优等不足，提出了一种基于Actor-Critic算法的路径规划方法。首先根据巡检目标和障碍物的实时位置信息，计算巡检机器人的转向角，确定行进方向，可显著提高路... 详细信息

针对现有矿用机器人路径路规划方法存在的效率低、收敛速度慢、易陷入局部最优等不足，提出了一种基于Actor-Critic算法的路径规划方法。首先根据巡检目标和障碍物的实时位置信息，计算巡检机器人的转向角，确定行进方向，可显著提高路径规划的效率；以能量消耗最小化和避免碰撞为目标，巡检机器人根据动态随机变化的矿山环境，学习巡检的目标顺序和行进速度；因为矿山环境动态连续变化，导致较高的状态维度，因此采用深度学习网络估计连续状态产生的动作和奖赏；为了提高学习效率，采用策略网络和价值网络2个网络，实现实时更新策略和价值。仿真结果表明：采用所提方法，巡检机器人可以在动态环境中规划出安全合理的巡检路线，能够以98%的成功概率和更低的能量消耗完成巡检作业。

关键词：巡检机器人路径规划深度强化学习避障能量消耗

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迁地保护应当具有明确的灵活性

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生物多样性 2024年第2期32卷 8-11页

作者：刘夙杜诚胡永红上海辰山植物园上海201602

早期的新闻报道中提到国家植物园体系“逐步实现中国85%以上野生本土植物、全部重点保护野生植物种类得到迁地保护”的建设目标引发了质疑。实际上,《中国植物园体系布局方案》明确了更为实际的目标,包括到2025年设立5个左右国家植物园... 详细信息

早期的新闻报道中提到国家植物园体系“逐步实现中国85%以上野生本土植物、全部重点保护野生植物种类得到迁地保护”的建设目标引发了质疑。实际上,《中国植物园体系布局方案》明确了更为实际的目标,包括到2025年设立5个左右国家植物园,实现70%以上的国家重点保护野生植物得到迁地保护;到2035年设立10个左右国家植物园,实现80%以上的国家重点保护野生植物得到有效迁地保护。植物园体系应当建立明确的迁地保护分级标准,即使在迁地栽培无法达到最高级别的保护标准时,仍可视为某种较低级别的迁地保护。迁地保护工作应与中国植物园体系有机结合,包括国家植物园、地区优秀植物园和地方植物园。通过全国植物引种数据联网共享的可能性,区域性和基层植物园可参与到迁地保护工作中,共同承担任务份额。迁地保护与就地保护、引种驯化并非对立的关系。就地保护优于迁地保护,但二者是相辅相成的关系。迁地保护和引种驯化并非绝对对立,可实现既保护又开发的目标。总体而言,未来迁地保护工作的一个重要方向是建立清晰的分级标准和数据网络,以明确迁地保护与其他保护形式的关系,实现明确的灵活性。

关键词：国家植物园体系迁地保护灵活性

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