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基于介质碳化通道电阻与温度映射关系的光伏直流汇集系统早期故障判别

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电网技术 2024年第4期48卷 1645-1653,I0075,I0077,I0078页

作者：张旸贾科张恬昕施志明毕天姝新能源电力系统国家重点实验室(华北电力大学) 北京市昌平区102206 新能源与储能运行控制国家重点实验室(中国电力科学研究院有限公司) 北京市海淀区100192

光伏中压直流汇集系统中,极间短路故障过流很可能迫使换流器在几毫秒内闭锁,保护来不及动作,引发整个系统停运。该问题可通过提前识别并隔离直流线路中的早期故障来解决。然而在直流线路上,早期故障与绝缘缺陷尚缺乏明确的边界,故障检... 详细信息

光伏中压直流汇集系统中,极间短路故障过流很可能迫使换流器在几毫秒内闭锁,保护来不及动作,引发整个系统停运。该问题可通过提前识别并隔离直流线路中的早期故障来解决。然而在直流线路上,早期故障与绝缘缺陷尚缺乏明确的边界,故障检测判据的阈值难以给定。为此,该文提出了基于碳化通道电阻与温度映射关系的早期故障边界给定原则。基于早期故障发展机理,建立了电缆早期故障实验拟合模型,选取介质碳化通道电阻为故障特征量。在计及系统电压控制约束条件下,解析电缆层间温差与碳化通道电阻的映射关系,进而确定早期故障边界。在此基础上提出了基于故障介质碳化通道电阻值的早期故障判据。仿真结果证明了早期故障边界的合理性以及早期故障判据的有效性,能够为光伏中压直流汇集系统的持续安全运行提供保障。

关键词：直流汇集系统早期故障故障边界故障判别

基于动态谱线插值的新能源场站同步基准信号检测方法

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电网技术 2024年第1期48卷 229-237页

作者：施志明董玮张军军吴福保新能源与储能运行控制国家重点实验室(中国电力科学研究院有限公司) 北京市海淀区100192 合肥工业大学电气与自动化工程学院安徽省合肥市230009

在含高比例新能源的低惯量电力系统中,系统频率呈现基频偏移严重、频率变化快等特征,导致新能源场站在进行并网测试及支撑性能评估时,同步基准信号检测误差增大,进而可能威胁到系统的安全稳定运行。对此,提出基于动态双离散傅里叶变换类... 详细信息

在含高比例新能源的低惯量电力系统中,系统频率呈现基频偏移严重、频率变化快等特征,导致新能源场站在进行并网测试及支撑性能评估时,同步基准信号检测误差增大,进而可能威胁到系统的安全稳定运行。对此,提出基于动态双离散傅里叶变换类(discrete Fourier transformation,DFT)谱线插值的同步基准信号检测算法。通过分析低惯量电力系统受功率扰动后的频率动态响应,揭示系统中基频静动态特征,并在此基础上建立静动态电网信号分析模型。进而量化基频偏移场景下的传统DFT谐波检测算法误差,并说明谱线插值类DFT算法在动态基频场景下的失效机理。继而利用希尔波特黄变换(Hibert-Huang transform,HHT)算法识别动态基频,并结合双DFT谱线插值法修正基频及谐波信号幅值,提高检测精度。又为改善检测效率,增设算法选择判据。试验测试结果表明:所提的检测算法能够准确的测量出强动态电网信号中的基准量,提高对新能源场站同步支撑、电能质量等并网性能的评估精度,为新能源高占比电力系统的同步基准信号检测提供新的可选方案。

关键词：基频偏移频率变化率基准信号检测低惯量电力系统新能源场站并网测试

习近平文化思想的逻辑体系、时代特征及现实价值

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河南师范大学学报（哲学社会科学版） 2024年第1期51卷 1-7,F0002页

作者：汪荣有史志明江西师范大学马克思主义学院江西南昌330022

习近平文化思想围绕建设具有强大凝聚力与引领力的意识形态这一战略定位,明确了建设中华民族现代文明的文化新使命,坚持以培育与践行社会主义核心价值观为价值引领,创新“两个结合”的文化实践方略,以党对宣传思想文化工作的全面领导为... 详细信息

习近平文化思想围绕建设具有强大凝聚力与引领力的意识形态这一战略定位,明确了建设中华民族现代文明的文化新使命,坚持以培育与践行社会主义核心价值观为价值引领,创新“两个结合”的文化实践方略,以党对宣传思想文化工作的全面领导为根本保障,稳步推进社会主义文化建设,构成了逻辑严密的理论体系,体现了鲜明的真理性、科学性、实践性的时代特征,进一步深化了社会主义文化的发展规律。习近平文化思想为实现中国式现代化、建设中华民族现代文明、推进人类文明新发展提供了理论遵循与实践指引。

关键词：习近平文化思想中华民族现代文明逻辑体系价值

Suppressed formation of CO_2 and H_2O in the oxidative coupling of methane over La_2O_3/MgO catalyst by surface modification

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Journal of Natural Gas Chemistry 2010年第2期19卷 173-178页

作者： zhiming Gao Yingxiao shi Department of Chemistry School of Science Beijing Institute of Technology Beijing 100081 China

Oxidative coupling of methane （OCM） is a promising way to convert methane into C2 ***,CO2 and H2O are by-products of the *** utilize the higher activity of lanthanum oxide and save its usage,MgO supported La2O3 catalyst was *** modification of the catalyst with nitric acid was made to suppress the formation of the *** results indicated that the addition of nitric acid increased the surface oxygen species with binding energy of ca.531.7 eV and at the same time reduced the pore volume of the *** effects of nitric acid finally led to the increase of C2 selectivity and the decrease of the by-products *** selectivity was found about 14%-18% over the catalysts adopted in this work.

关键词： methane oxidative coupling catalyst design XPS magnesium oxide

Network video quality assessment based on fuzzy inference system

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The Journal of China Universities of Posts and Telecommunications 2018年第1期25卷 70-77页

作者： shi zhiming Huang Chengti College of Engineering Huaqiao University Quanzhou 362021 China Fujian Provincial Academic Engineering Research Centre in Industrial Intellectual Techniques and Systems Quanzhou 362021 China

The objective assessment method of network video quality is a challenge, because the video quality will be distorted by various factors, including transmission and compression. In order to improve the objective method, an objective assessment method based on fuzzy inference system of Mamdani is proposed. Firstly, six quality parameters are introduced. All the quality parameters are inputted to fuzzy logic controller system. Secondly, the outputs are used as next inputs and inferred by another fuzzy logic controller system to obtain the objective quality of network video. Lastly, the performance of proposed method is validated on four videos with different network environment. Meanwhile this method is compared with other methods. The experimental results show that the proposed method can improve the similarity between subjective and objective assessment.

关键词： network video quality parameter fuzzy inference system objective assessment

Quality of experience models for network video quality

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The Journal of China Universities of Posts and Telecommunications 2019年第4期26卷 80-88页

作者： shi zhiming Huang Chengti College of Engineering Huaqiao UniversityQuanzhou 362021China Fujian Provincial Academic Engineering Research Centre in Industrial Intellectual Techniques and Systems Huaqiao UniversityQuanzhou 362021China

Nowadays,the service of network video is increasing *** the quality of experience(QoE)model of network video quality is not *** video quality may be impaired by many *** paper proposes QoE models for network video *** consists of two components:1)the perceptual video quality model considering the impair factors related to video content as well as distortion caused by content and *** the model is built through a decision tree using a set of measured features form the network *** proposed model can qualitatively give the grade of video quality and improve the accuracy of prediction.2)Based on the above model,another model is proposed to give the concrete objective score of video *** also considers original impair factors and predicts the video quality using fuzzy decision *** two models have their own *** first model has a good computational complexity;the second model is more *** the models are simulated by actual *** can improve the accuracy of objective *** detail results are shown.

关键词： perceptual video quality QoE objective model fuzzy decision tree accuracy

钇对高强高导Cu-Cr-Zr合金组织与性能的影响

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中国稀土学报 2024年第2期42卷 294-303,I0004页

作者：张成功乔振兴史志铭新巴雅尔峰山刘慧敏敖敏内蒙古工业大学材料科学与工程学院多功能铜材料内蒙古自治区工程研究中心内蒙古呼和浩特010051

采用非真空熔炼和近液相线铸造相结合的方法制备Cu-Cr-Zr-Y合金,并对其进行固溶、室温轧制与时效处理,研究Y对Cu-Cr-Zr合金组织与性能的影响。结果表明,Cu-0.6Cr-0.14Zr-0.15Y合金的铸态组织为均匀细小的等轴晶,平均晶粒尺寸约为11μm。... 详细信息

采用非真空熔炼和近液相线铸造相结合的方法制备Cu-Cr-Zr-Y合金,并对其进行固溶、室温轧制与时效处理,研究Y对Cu-Cr-Zr合金组织与性能的影响。结果表明,Cu-0.6Cr-0.14Zr-0.15Y合金的铸态组织为均匀细小的等轴晶,平均晶粒尺寸约为11μm。Y的加入抑制时效过程中Cr元素的析出。Cu-0.6Cr-0.14Zr-0.15Y合金中出现纳米级Cr,Cu_(5)Zr,CuY析出相和纳米孪晶,平均尺寸分别为5~20nm和15nm。Cu-0.6Cr-0.14Zr-0.15Y合金经固溶-室温轧制-时效后,抗拉强度达到550MPa,相对电导率达到85%IACS,较相同后处理条件下的Cu-0.6Cr-0.14Zr合金抗拉强度提高了27.3%、相对电导率下降了3.4%。

关键词：稀土Y Cu-Cr-Zr合金微观组织抗拉强度相对电导率

Anodic hydrogen evolution on Mg

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Journal of Magnesium and Alloys 2021年第6期9卷 2049-2062页

作者： Yang Li zhiming shi Xingrui Chen Andrej Atrens School of Mechanical and Mining Engineering Centre for Advanced Materials and ProcessingThe University of QueenslandSt LuciaQLD 4072Australia

We measured the anodic hydrogen evolution rates for various applied anodic current densities and estimated the corresponding cathodic hydrogen evolution *** estimated cathodic hydrogen evolution rates were less than the measured anodic hydrogen evolution rates,contradicting the enhanced catalytic activity mechanism of Mg *** addition,this model was contradicted by the measured apparent Mg valence of 1.2±*** contrast,the uni-positive Mg^(+)mechanism of Mg corrosion was supported by(i)the apparent Mg valence of 1.2±0.1,and(ii)the fact that the measured anodic hydrogen evolution rate increased with increasing weight loss rate.

关键词： A magnesium B Galvanostatic Potentiostatic Weight loss Hydrogen evolution C Negative difference effect

Effect of Shot Peening on Surface Damage Evolution Behavior of Cu-19Ni Alloy

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Journal of Wuhan University of Technology(Materials Science) 2023年第1期38卷 212-221页

作者：朱旭军李磊 shi zhiming WEI Liangyu TIAN Fuzheng College of Sciences Inner Mongolia University of TechnologyHohhot 010051China School of Materials Science and Engineering Inner Mongolia University of TechnologyHohhot 010051China

Shot peening is a surface modification technology with the metal surface nano machine(SNC),which can modify the surface microstructure and extend the fatigue life of Cu-19Ni *** hardness,damage evolution and mechanical properties were investigated and characterized by scanning electron microscope(SEM),laser confocal microscope(LSM)and material surface performance tester(CFT).The results showed that the surface roughness and friction coefficient of Cu-19Ni alloy decreased with the increase of shot peening duration and diameter,while the microhardness and strength ***,with the increase in shot peening duration and diameter,SEM observation showed that the fracture dimples became smaller,meanwhile,with the increase of small cleavage planes,shear tearing ridges and the thickness of the surface nano layer,the fracture mode gradually evolved from plastic to brittle *** uniaxial tensile test of shot peened Cu-19Ni alloy was carried out by MTS testing machine combined with digital image correlation technology(DIC).The evolution of Cu-19Ni surface damage was analyzed,and the evolution equations describing the damage of large deformation zone and small deformation zone were *** effect of shot peening on the damage evolution behavior of Cu-19Ni alloy was revealed.

关键词： Cu-19Ni alloy shot peening damage evolution mechanical properties digital image correlation