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Sparse time-frequency representation of nonlinear and nonstationary data Dedicated to Professor shi Zhong-Ci on the Occasion of his 80th Birthday

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Science China Mathematics 2013年第12期56卷 2489-2506页

作者： HOU Thomas Yizhao shi ZuoQiang Department of Computing and Mathematical Sciences California Institute of Technology Mathematical Sciences Center Tsinghua University

Adaptive data analysis provides an important tool in extracting hidden physical information from multiscale data that arise from various applications. In this paper, we review two data-driven time-frequency analysis methods that we introduced recently to study trend and instantaneous frequency of nonlinear and nonstationary data. These methods are inspired by the empirical mode decomposition method （EMD） and the recently developed compressed （compressive） sensing theory. The main idea is to look for the sparsest representation of multiscale data within the largest possible dictionary consisting of intrinsic mode functions of the form {a（t） cos（0（t））}, where a is assumed to be less oscillatory than cos（θ（t）） and θ ＇≥ 0. This problem can be formulated as a nonlinear ι0 optimization problem. We have proposed two methods to solve this nonlinear optimization problem. The first one is based on nonlinear basis pursuit and the second one is based on nonlinear matching pursuit. Convergence analysis has been carried out for the nonlinear matching pursuit method. Some numerical experiments are given to demonstrate the effectiveness of the proposed methods.

关键词： sparse representation time-frequency analysis data-driven

农业减排固碳对黄河流域农业经济高质量发展影响的空间效应

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西北农林科技大学学报（社会科学版） 2025年第1期25卷 128-139页

作者：石建文杨秀云西安交通大学经济与金融学院西安710049

运用IPCC方法测算2000-2020年黄河流域农牧业减排固碳水平,构建指标体系测算农业经济高质量发展水平,应用空间杜宾模型探讨农业减排固碳对黄河流域农业经济高质量发展的影响。结果显示:(1)农业减排固碳水平整体呈现“先下降后保持平稳... 详细信息

运用IPCC方法测算2000-2020年黄河流域农牧业减排固碳水平,构建指标体系测算农业经济高质量发展水平,应用空间杜宾模型探讨农业减排固碳对黄河流域农业经济高质量发展的影响。结果显示:(1)农业减排固碳水平整体呈现“先下降后保持平稳再上升”的变化趋势,区域整体减排固碳能力较好;(2)2000-2020年,黄河流域农业经济高质量发展水平呈现波动上升态势,各地级市农业经济高质量发展水平的内部差异较大;(3)整体而言,减排固碳和经济增长水平对正面促进农业经济高质量发展的影响主要源于区域间的经济关联,农业技术创新、外商直接投资正面促进农业经济高质量发展的影响主要源于区域间的地理位置,环境规制、人口规模对农业经济高质量发展的负向影响主要受到地区间的经济关联,城镇化水平负向抑制农业经济高质量发展的影响主要源于区域间的地理位置;(4)分地区而言,减排固碳对黄河流域农业经济高质量发展的作用效果及程度均存在异质性。

关键词：减排固碳农业经济高质量发展空间杜宾模型黄河流域

Double [5]carbohelicene: facile synthesis, chiroptical properties,isomerization study, and lasing application

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Science China Chemistry 2025年第1期 233-240页

作者： Peipei Liu Yantong Li Meng-Xiang Wu Hao Kang Xiao-Li Zhao Lin Xu Linlin Liu Xiaodong Li Junfeng Fang Zhiwei Fang Ya Cheng Hai-Bo Yang Huakang Yu Xueliang shi State Key Laboratory of Petroleum Molecular & Process Engineering Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesSchool of Chemistry and Molecular Engineering East China Normal University School of Physics and Optoelectronics South China University of Technology Institute of Polymer Optoelectronic Materials & Devices State Key Laboratory of Luminescent Materials & Devices South China University of Technology School of Physics and Electronic Science Engineering Research Center of Nanophotonics & Advanced Instrument Ministry of EducationEast China Normal University State Key Laboratory of Precision Spectroscopy School of Physics and Electronic Science East China Normal University

Double carbohelicenes have attracted considerable attention due to their aesthetic structures, distinct π-conjugation extension, inherent chirality, and intriguing optical and electronic properties. Herein, the concise de novo synthesis of a new double[5]carbohelicene 1 together with its chiroptical properties, isomerization process and lasing application is presented. 1 was synthesized by a simple protocol involving the formation of a 6,6′-bipentacene as the key intermediate. It is worth noting that1 existed as two diastereomers 1-PP/MM and 1-PM, which were successfully isolated and unambiguously confirmed by Xray crystallography. The optical resolution of the racemic 1-PP/MM was successfully achieved by chiral-phase highperformance liquid chromatography（HPLC）, and 1-PP and 1-MM were characterized by circular dichroism. Interestingly, it was found that 1-PP/MM could be completely isomerized to 1-PM upon heating, and the detailed thermodynamics and kinetics of the isomerization process were systematically investigated. 1-PM exhibited deep-red luminescence with emission maximum at 723 nm and fluorescence quantum yield as high as 32.95%. Consequently, we can showcase the lasing application of 1-PM by doping with epoxy resin to assemble a bottle microlaser spontaneously, which the lasing wavelength is 796.6 nm at a threshold of 0.8 m J cm-2. We believe that our studies, including the facile synthesis methodology, detailed isomerization studies, and lasing application, will shed some light on the design and synthesis of novel carbohelical systems with more functions.

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基于区块链的车联网跨域数据安全传输系统设计

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现代电子技术 2025年第1期48卷 71-79页

作者：陈晨王斓凯施佺南通大学信息化中心江苏南通226019 南通大学交通与土木工程学院江苏南通226019

为有效应对车联网系统在数据传输过程中的安全问题,提出一种基于区块链的车联网跨域数据安全传输系统。该系统将车联网安全数据传输过程划分为注册、安全通信与数据共享三个关键环节。在注册阶段,车辆和路边单元需要通过可信机构完成注... 详细信息

为有效应对车联网系统在数据传输过程中的安全问题,提出一种基于区块链的车联网跨域数据安全传输系统。该系统将车联网安全数据传输过程划分为注册、安全通信与数据共享三个关键环节。在注册阶段,车辆和路边单元需要通过可信机构完成注册,以确保其的身份合法性;在通信阶段,为了减少路边单元与车辆频繁认证,设计了跨域认证的方法,保障数据传输的可靠性和完整性,并引入假名来保护用户隐私;在共享阶段,文中设计了基于多线程遍历共享广播森林的事务广播算法,利用广度优先搜索思想建立广播森林,并使用多线程遍历进行数据事务广播传输。实验仿真结果显示,文中方案的签名计算成本减少70%,验证计算成本减少41%;其次,在ER模型下,相比使用Gossip协议进行事务数据传输,该方案中交通数据事务总时间降低了93%;在BA模型下降低了87%。

关键词：区块链车联网身份认证密钥协商广播森林数据安全传输系统

miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells

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Neural Regeneration Research 2025年第1期20卷 277-290页

作者： Meng Cong Jing-Jing Hu Yan Yu Xiao-Li Li Xiao-Ting Sun Li-Ting Wang Xia Wu Ling-Jie Zhu Xiao-Jia Yang Qian-Ru He Fei Ding Hai-Yan shi School of Medicine Nantong UniversityNantongJiangsu ProvinceChina Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education and Coinnovation Center of Neuroregeneration Nantong UniversityNantongJiangsu ProvinceChina Department of Physiology Jiangsu Health Vocational CollegeNanjingJiangsu ProvinceChina Department of Pathology Affiliated Hospital of Nantong UniversityNantongJiangsu ProvinceChina Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair Affiliated Hospital of Nantong UniversityNantongJiangsu ProvinceChina

Our previous study found that rat bone marrow–derived neural crest cells(acting as Schwann cell progenitors)have the potential to promote long-distance nerve ***-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular ***,the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain *** investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves,we collected conditioned culture medium from hypoxia-pretreated neural crest cells,and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose *** mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest *** performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest ***,to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons,we used a microfluidic axonal dissociation model of sensory neurons in vitro,and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons,which was greatly dependent on loaded ***,we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb,as well as muscle tissue morphology of the hind limbs,were obviously *** findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in ***-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell *** helps to explain the mechanism of action of the secretome and e

关键词： axotomy cell-free therapy conditioned medium extracellular vesicles hypoxic preconditioning microRNA oxygen-glucose deprivation peripheral nerve injury Schwann cell precursors

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基于热压处理的聚芳醚介电损耗降低

大连理工大学学报 2025年第1期65卷 10-16页

作者：石龙威王锦艳蹇锡高大连理工大学化工学院辽宁大连116024

限制极性分子的运动是降低聚合物介电损耗的有效手段.合成了含杂萘联苯结构的聚芳醚,随后进行热压处理以降低其自由体积,限制分子链段运动,从而降低材料的介电损耗.实验结果表明,系列聚芳醚薄膜在热压处理后的介电损耗明显降低,降低率... 详细信息

限制极性分子的运动是降低聚合物介电损耗的有效手段.合成了含杂萘联苯结构的聚芳醚,随后进行热压处理以降低其自由体积,限制分子链段运动,从而降低材料的介电损耗.实验结果表明,系列聚芳醚薄膜在热压处理后的介电损耗明显降低,降低率最大为10.27%;材料自由体积的降低也使其玻璃化转变温度提高,提高率最大为13.0%.采用XRD测试并计算材料的分子链间距以反映材料自由体积的变化,应用Materials Studio软件模拟聚芳醚于热压前后的自由体积分数的变化,二者均与材料的介电损耗、玻璃化转变温度变化规律相符,证明通过热压处理降低材料自由体积以提升其性能是一种可行手段.

关键词：聚芳醚介电损耗热压分子模拟

Exit options sustain altruistic punishment and decrease the second-order free-riders, but it is not a panacea

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Science China(Information Sciences) 2025年第1期 278-291页

作者： Chen SHEN Zhao SONG Lei shi Jun TANIMOTO Zhen WANG Faculty of Engineering Sciences Kyushu University School of Statistics and Mathematics Yunnan University of Finance and Economics School of Computing Engineering and Digital Technologies Teesside University School of Artificial Intelligence OPtics and Electro Nics (iOPEN) Northwestern Polytechnical University

Why do humans punish free riders at their own expense? This behavior represents an evolutionary puzzle in human societies. This study explores the role of exit strategies in fostering altruistic punishment within evolutionary game theory. We extend the traditional prisoner's dilemma model by incorporating exiters, players who opt out for a small payoff while nullifying their opponent's payoff, and altruistic punishers who cooperate and punish non-cooperators. Our findings indicate that in well-mixed populations, exiters destabilize defection but do not promote altruistic punishment. In social networks, however,exiters enable altruistic punishment via cyclic dominance among altruistic punishers, defectors, and exiters. Notably, this cyclic dominance is sensitive to exit payoffs; adjustments can lead to cyclic dominance of non-punishing cooperators, defectors, and exiters, or to a bi-stable state between these two types of cyclic dominance. These results highlight the nuanced impact of exiters on altruistic punishment, emphasizing the need for careful incentivization of exit behavior. While exiters can support altruistic punishment in networked populations, their effectiveness is not a panacea and is highly sensitive to exit payoffs, indicating limits to the voluntary participation mechanism.

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Deep Synchronization Control of Grid-Forming Converters:A Reinforcement Learning Approach

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 273-275页

作者： Zhuorui Wu Meng Zhang Bo Fan Yang shi Xiaohong Guan the School of Cyber Science and Engineering Xi'an Jiaotong University the Department of Mechanical Engineering University of Victoria

Dear Editor,This letter proposes a deep synchronization control(DSC) method to synchronize grid-forming converters with power grids. The method involves constructing a novel controller for grid-forming converters based on the stable deep dynamics model. To enhance the performance of the controller, the dynamics model is optimized within the deep reinforcement learning(DRL) framework. Simulation results verify that the proposed method can reduce frequency deviation and improve active power responses.

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Scattering Function and Spinodal Transition of Linear and Nonlinear Block Copolymers Based on a Unified Molecular Model

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Chinese Journal of Polymer Science 2021年第6期39卷 779-788,I0009页

作者： Weichao shi Key Laboratory of Functional Polymer Materials of Ministry of Education Institute of Polymer ChemistryCollege of ChemistryNankai UniversityTianjin 300071China

This work uses a block copolymer architecture[(A′B)nA2]m to unify the scattering function and spinodal transition of typical AB-type block *** key roles of block number,junction points and asymmetry ratios of block length are(1)to determine the form factor of each block copolymer at the molecular scale;(2)to affect the entropy loss across the spinodal transition and may result in deflection of spinodal *** common features are validated in typical linear and nonlinear block copolymers,including AB diblock,asymmetric A′BA triblock,miktoarm stars of ABn,AnBn,(AB)n,(A′B)nA,A′BAm,and multi-graft combs of(BnA2)m and[(A′B)nA2]*** explicit scattering functions and form factors of various block copolymers can be directly applied in radiation experiments(*** or X-ray scattering)to unravel the effect of molecular architecture in solution and microphase separation in disordered *** molecular model used in this study is also helpful to guide the chemical synthesis to explore more potentially interesting block copolymers.

关键词： Scattering function Form factor Spinodal transition Molecular structure Block copolymer