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Fault Diagnosis with Wavelet Packet Transform and Principal Component Analysis for Multi-terminal Hybrid HVDC Network

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Journal of Modern Power Systems and Clean energy 2021年第6期9卷 1312-1326页

作者： tao li Yongli li Xiaolong Chen IEEE School of Electrical Automation and Information engineering Tianjin University

In view of the fact that the wavelet packet transform(WPT) can only weakly detect the occurrence of fault, this paper applies a fault diagnosis algorithm including wavelet packet transform and principal component analysis(PCA) to the inverter-side fault diagnosis of multi-terminal hybrid highvoltage direct current(HVDC) network, which can significantly improve the speed and accuracy of fault diagnosis. Firstly, current amplitude and current slope are used to sample the data,and the WPT is used to extract the energy spectrum of the signal. Secondly, an energy matrix is constructed, and the PCA method is used to calculate whether the squared prediction error(SPE) statistics of various signals that can reflect the degree of deviation of the measured value from the principal component model at a certain time exceed the limit to judge the occurrence of the fault. Further, its maximum value is compared to determine the fault types. Finally, based on a large number of MATLAB/Simulink simulation results, it is shown that the PCA method using the current slope as the sampled data can detect the occurrence of a ground fault with small transition resistance within 2 ms, and identify the fault types within 10 ms,without being affected by the sampling frequency.

关键词： Fault diagnosis hybrid high-voltage direct current(HVDC) wavelet packet transform(WPT) principal component analysis(PCA)

Deterministic measurement-device-independent quantum secret sharing

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Science China(Physics,Mechanics & Astronomy) 2020年第12期63卷 72-79页

作者： ZiKai Gao tao li ZhenHua li School of Science Nanjing University of Science and TechnologyNanjing 210094China

Multiparty quantum communication ensures information-theoretic security for transmitting private information among multiuser *** principle,measurement-device-independent(MDI)techniques can close all detection loopholes while usually utilizing large amounts of quantum resources in basis *** propose a three-party MDI quantum secret sharing(QSS)protocol that is secure against all detection attacks and does not require any basis reconciliation,avoiding the corresponding waste arising from *** proposed protocol allows a sender to divide a private message into two parts and send those parts to different receivers in a deterministic *** message can only be read through cooperation between the two ***,we discuss the generalized extension of a multiparty QSS protocol.

关键词： quantum information quantum communication quantum entanglement

Unconventional Hamilton-type variational principles for analytical mechanics

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Science China(Physics,Mechanics & Astronomy) 2007年第2期50卷 152-162页

作者： LUO en liANG liFu li WeiHua Department of Applied Mechanics and engineering Sun Yat-sen UniversityGuangzhou 510275China Department of Aerospace engineering Harbin Engineering UniversityHarbin 150001China

According to the basic idea of classical yin-yang complementarity and modern dual-complementarity, in a simple and unified new way proposed by Luo, the un-conventional Hamilton-type variational principles of holonomic conservative system in analytical mechanics can be established systematically. This unconventional Hamilton-type variational principle can fully characterize the initial-value problem of analytical mechanics, so that it is an important innovation for the Hamilton-type variational principle. In this paper, an important integral relation is given, which can be considered as the expression of the generalized principle of virtual work for analytical mechanics in mechanics. Based on this relation, it is possible not only to obtain the principle of virtual work of holonomic conservative system in analytical mechanics, but also to derive systematically the complementary functionals for three-field and two-field unconventional variational principles, and the functional for the one-field one by the generalized Legendre transformation given in this paper. Further, with this new approach, the intrinsic relationship among various principles can be explained clearly. Meanwhile, the unconventional Hamilton-type variational principles of nonholonomic conservative system in analytical mechanics can also be established systematically in this paper.

关键词： analytical mechanics holonomic and nonholonomic systems unconventional Hamilton-type variational principle dual-complementarity initial-value problem restricted variation

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我国未来学习中心建设现状与路径探索

大学图书情报学刊 2025年第1期43卷 37-42,65页

作者：李小涛解玲南京航空航天大学图书馆 210016 南京航空航天大学经济与管理学院 210016

建设未来学习中心,是推进高等教育数字化转型和高校图书馆服务升级的有效途径。调研未来学习中心建设现状及存在问题,可为我国高等院校未来学习中心建设实践提供参考借鉴。文章运用文献调研和网络调查的方法,从顶层设计、建设理念、空... 详细信息

建设未来学习中心,是推进高等教育数字化转型和高校图书馆服务升级的有效途径。调研未来学习中心建设现状及存在问题,可为我国高等院校未来学习中心建设实践提供参考借鉴。文章运用文献调研和网络调查的方法,从顶层设计、建设理念、空间建设、资源建设、服务创新5个维度对全国高等院校未来学习中心建设实践进行调查,并对调查结果进行归类、统计和分析。研究发现,我国未来学习中心建设正处于起步探索期,在具体实践中存在着顶层设计不足、技术应用与教学模式融合不深等问题。针对这些问题,文章提出了相应的建设路径。

关键词：未来学习中心高校图书馆建设现状网络调研

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高压脉冲电场处理对中国对虾抗氧化活性和蛋白质特性的影响

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食品与发酵工业 2025年第1期51卷 199-207页

作者：杨晨宇王肖园邓云陶宁萍李立邱伟强李峰金银哲上海海洋大学食品学院上海201306 食品热加工工程中心上海201306 上海交通大学农业与生物学院上海200240 上海电力大学电气工程学院上海200090

该研究目的是探讨不同高压脉冲电场处理对中国对虾抗氧化活性和蛋白质特性的影响。通过对脉冲电场处理(10~20 kV/cm,5~15 min)样品前后的总抗氧化能力、总还原能力、DPPH自由基清除能力、亚铁离子螯合能力以及虾青素含量的综合测定,衡... 详细信息

该研究目的是探讨不同高压脉冲电场处理对中国对虾抗氧化活性和蛋白质特性的影响。通过对脉冲电场处理(10~20 kV/cm,5~15 min)样品前后的总抗氧化能力、总还原能力、DPPH自由基清除能力、亚铁离子螯合能力以及虾青素含量的综合测定,衡量样品的抗氧化性强弱;对氨基酸含量、可溶性蛋白质含量和介电特性(1~10 GHz)的分析来探讨其对中国对虾蛋白质特性的影响。结果表明,高压脉冲电场处理能够提高虾肉的抗氧化能力,20 kV/cm条件下处理15 min时虾肉的总抗氧化活性、总还原能力、DPPH自由基清除能力以及亚铁离子螯合能力分别提升了15.88%、36.51%、62.14%和43.52%。在15 kV/cm和20 kV/cm电场强度下,虾青素含量和游离氨基酸含量随处理时间的增加逐渐上升(P<0.05),且虾青素含量最高增加了1.61倍,其含量变化与虾肉抗氧化活性变化显著相关(P<0.05)。此外,与未处理组相比,脉冲电场处理后虾肉中必需氨基酸与非必需氨基酸含量比值均显著提高(P<0.05);且介电常数随可溶性蛋白质含量的降低逐渐增加(P<0.05)。高压脉冲电场处理能够增强虾肉的抗氧化活性,提高蛋白质品质和氨基酸利用率,为中国对虾的加工方式和生物活性增强提供了新思路。

关键词：高压脉冲电场中国对虾抗氧化活性蛋白质特性虾青素氨基酸

Spindle liFePO_4 particles as cathode of lithium-ion batteries synthesized by solvothermal method with glucose as auxiliary reductant

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Rare Metals 2015年第10期34卷 731-737页

作者： li Ren Xing-en li Fang-Fang Wang Yang Han Polymer Research Institute College of Chemical EngineeringHebei University of Technology

The well-distribution spindle li Fe PO4(LFP)nanoparticles as cathode of lithium secondary batteries were synthesized by a solvothermal reaction route at low temperature(180 °C) in which the ascorbic acid was used as reducing agent. In order to guarantee that the p H values of thermal systems were not affected too much and the reducibility of the system was enhanced at the same time,glucose was chosen as an auxiliary reductant in this reaction. The obtained powders were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM),and laser particle analyzer. The results show that the carbon-coated uniform spindle olivine li Fe PO4/C-glucose particles(glucose as auxiliary reductant, LFP/C-G) are prepared with the size 500–600 nm and without any impurity phases. Their electrochemical properties were evaluated by electrochemical impedance spectroscopy,cyclic voltammetry, and galvanostatic charge/discharge tests. LFP/C-G has a higher conductivity and better reversible capability than carbon-coated LFP(LFP/C). The highest discharge capacity of LFP/C-G is 161.3 mAh·g-1at0.1C and 108.6 mAh·g-1at 5.0C, respectively. The results imply that the neat crystal nanostructure of LFP/C-G has excellent capacity retention and cycling *** adding of glucose is the key factor for the welldistribution and neat crystal structure of nanoparticles,thus the electrochemical performances of materials are improved.

关键词： lithium-ion battery liFePO4 Spindle Solvothermal G

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运动对大学生肠道菌群影响的系统综述

中国组织工程研究 2025年第11期29卷 2394-2401页

作者：刘昭志黄丽田浩冬李岚陈晓陶云飞彭莉西南大学体育学院重庆市400715 西南大学体育学院国家体育总局体质评价与运动机能监控重点实验室重庆市400715 山东中医药大学健康学院山东省济南市250000

背景:运动对肠道菌群的调节与人体健康密切相关,但肠道菌群涉及多方面因素影响,国内外研究尚缺乏有关运动对大学生肠道菌群影响的较为一致的证据。目的:探讨运动对大学生肠道菌群多样性和物种组成的影响。方法:通过系统检索PubMed、Web ... 详细信息

背景:运动对肠道菌群的调节与人体健康密切相关,但肠道菌群涉及多方面因素影响,国内外研究尚缺乏有关运动对大学生肠道菌群影响的较为一致的证据。目的:探讨运动对大学生肠道菌群多样性和物种组成的影响。方法:通过系统检索PubMed、Web of Science、Embase、Medline、Cochrane library、中国知网、万方、维普数据库,筛选后纳入8篇实证研究,对其采用半定量的方法进行分析。结果与结论:①在运动改变大学生肠道菌群物种多样性方面,高强度间歇训练和太极拳运动均能显著提升大学生肠道菌群的物种多样性,而有氧运动对大学生肠道菌群多样性的提升效果不显著;②在运动影响肠道菌群物种组成方面,3种运动方式均能显著改变大学生肠道中菌群的组成结构,可以提高瘤胃球菌、普氏粪杆菌、布劳提亚菌等有益菌的丰度,降低埃希氏菌属等有害菌的丰度;相较于高强度间歇训练,有氧运动和太极拳运动引起了更多有益菌丰度的提升;③除肠道菌群特征的变化外,运动还可以改善大学生体成分、心肺功能以及执行功能等,这些健康效益与运动引起的菌群变化密切相关,这些菌群可通过代谢调节、屏障功能以及神经调节对机体产生健康效益;④虽然目前已有研究证实了运动与肠道菌群存在关联,但运动影响肠道菌群的机制尚未明确,同时定位与宿主健康相关的菌群是未来以肠道菌群为治疗靶点的关键,这些均值得学者进一步关注和探究。

关键词：运动干预大学生肠道菌群菌群多样性物种组成

The Nonexistence of Expansive Z^d Actions on Graphs

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Acta Mathematica Sinica,english Series 2005年第6期21卷 1509-1514页

作者： en Hui SHI li Zhen ZHOU Department of Mathematics University of Science and Technology of China Hefei 230026 P. R. China Department of Mathematics Suzhou University Suzhou 215006 P. R. China

It is well known that if X is an arc or a circle, then there is no expansive homeomorphism on X. In this paper we prove that there is no expansive Z^d action on X, which answers the two questions raised by us before, In 1979, Mané proved that there is no expansive homeomorphism on infinite dimensional spaces. Contrary to this result, we construct an expansive Z^2 action on an infinite dimensional space. We also construct an expansive Z^2 action on a zero dimensional space but no element in Z^2 is expansive.

关键词： Expansive homeomorphism Arc Circle Group action

Down-regulation of transforming growth factor β1/activin receptor-like kinase 1 pathway gene expression by herbal compound 861 is related to deactivation of LX-2 cells

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World Journal of Gastroenterology 2008年第18期14卷 2894-2899页

作者： li li Xin-Yan Zhao Bao-en Wang liver Research Center Beijing Friendship Hospital Capital Medical University Beijing 100050 China

AIM: To investigate the effect of herbal compound 861 (Cpd861) on the transforming growth factor-β1 (TGFβ1)/ activin receptor-like kinase 1 (ALK1, type Ⅰ receptor) signaling-pathway-related gene expression in the LX-2 cell line, and the inhibitory mechanism of Cpd861 on the activation of LX-2 cells. METHODS: LX-2 cells were treated with TGFβ1 (5 ng/mL) Cpd861 (0.1 mg/mL), TGFβ1 (5 ng/mL) plus Cpd861 (5 ng/mL) for 24 h to investigate the effect of Cpd861 on the TGFβ1/ALK1 pathway. Real-time PCR was performed to examine the expression of α-SMA (α-smooth muscle actin), ALK1, Id1 (inhibitor of differentiation 1). Western blotting was carried out to measure the levels of α-SMA and phosphorylated Smad1, and immunocytochemical analysis for the expression of α-SMA. RESULTS: In LX-2 cells, TGFβ1/ALK1-pathway-related gene expression could be stimulated by TGFβ1, which led to excessive activation of the cells. Cpd861 decreased the activation of LX-2 cells by reducing the expression of α-SMA mRNA and protein expression. This effect was related to inhibition of the above TGFβ1/ALK1-pathway- related expression of genes such as Id1 and ALK1, and phosphorylation of Smad1 in LX-2 cells, even with TGFβ1 co-treatment for 24 h. CONCLUSION: Cpd861 can restrain the activation of LX-2 cells by inhibiting the TGFβ1/ALK1/Smad1 pathway.

关键词： Herbal compound 861 LX-2 cell Activin receptor-like kinase 1 Inhibitor of differentiation 1 Smad1