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Journal of Integrative Plant Biology 2007年第3期49卷 401-407页

作者： weixin cheng Feike A. Dijkstra Environmental Studies University of California Santa Cruz CA 95064 USA

Continuous Isotope labeling and tracing is often needed to study the transformation, movement, and allocation of carbon in plant-soil systems. However, existing labeling methods have numerous limitations. The present study Introduces a new continuous labeling method using naturally ^13C-depleted CO2. We theoretically proved that a stable level of ^13C-CO2 abundance in a labeling chamber can be maintained by controlling the rate of CO2-free air Injection and the rate of ambient airflow with coupling of automatic control of CO2 concentration using a CO2 analyzer. The theoretical results were tested and confirmed in a 54 day experiment in a plant growth chamber. This new continuous labeling method avoids the use of radioactive ^14C or expensive ^13C-enrlched CO2 required by existing methods and therefore eliminates issues of radiation safety or unaffordable isotope cost, as well as creating new opportunities for short- or long-term labeling experiments under a controlled environment.

关键词： carbon flux CO2 isotope rhizosphere tracers

基于形态学构建尺度空间与谱峭度的轴承故障诊断方法

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轴承 2025年第1期 95-101页

作者：杨旭刘鹏飞程伟欣许增兵刘泽潮石家庄铁道大学机械工程学院石家庄050043 石家庄铁道大学省部共建交通工程力学行为与系统安全国家重点实验室石家庄050043

针对高速列车轴箱轴承服役环境恶劣,故障特征难以提取的问题,提出了基于形态学构建尺度空间表征的经验小波变换(EWT)故障诊断方法。首先,提出基于形态学的尺度空间表征方法,实现共振频带边界的自适应识别;其次,将基于形态学构建的尺度... 详细信息

针对高速列车轴箱轴承服役环境恶劣,故障特征难以提取的问题,提出了基于形态学构建尺度空间表征的经验小波变换(EWT)故障诊断方法。首先,提出基于形态学的尺度空间表征方法,实现共振频带边界的自适应识别;其次,将基于形态学构建的尺度空间表征与谱峭度相结合,识别出共振频带;然后,根据所识别的频带边界构造滤波器组,对信号进行自适应分解;最后,对分解信号进行包络谱分析,识别故障特征频率,实现轴承故障的诊断。高速列车轴箱轴承振动试验结果表明,该方法能够有效提高频带划分的准确性以及计算效率,准确诊断轴承故障。

关键词：滚动轴承故障诊断小波变换形态学尺度空间峭度

Priming effect and its regulating factors for fast and slow soil organic carbon pools: A meta-analysis

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Pedosphere 2022年第1期32卷 140-148页

作者： Changfu HUO Junyi LIANG Weidong ZHANG Peng WANG weixin cheng Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China Department of Grassland Resources and Ecology College of Grassland Science and TechnologyChina Agricultural UniversityBeijing 100083China Environmental Studies Department University of CaliforniaSanta Cruz CA 95064USA

The priming effect (PE) plays a critical role in the control of soil carbon (C) cycling and influences the alteration of soil organic C (SOC) decomposition by fresh C ***,drivers of PE for the fast and slow SOC pools remain unclear because of the varying results from individual *** meta-analysis in combination with boosted regression tree (BRT) analysis,we evaluated the relative contribution of multiple drivers of PE with substrate and their patterns across each driver *** results showed that the variability of PE was larger for the fast SOC pool than for the slow SOC *** on the BRT analysis,67%and 34%of the variation in PE were explained for the fast and slow SOC pools,*** were seven determinants of PE for the fast SOC pool,with soil total nitrogen (N) content being the most important,followed by,in a descending order,substrate C:N ratio,soil moisture,soil clay content,soil pH,substrate addition rate,and SOC *** directions of PE were negative when soil total N content and substrate C:N ratio were below 2 g kg~(-1)and 20,respectively,but the directions changed from negative to positive with increasing levels of this two *** with optimal water content (50%–70%of the water-holding capacity) or moderately low pH (5–6) were prone to producing a greater *** the slow SOC pool,soil p H and soil total N content substantially explained the variation in *** magnitude of PE was likely to decrease with increasing soil pH for the slow SOC *** addition,the magnitude of PE slightly fluctuated with soil N content for the slow SOC ***,this meta-analysis provided new insights into the distinctive PEs for different SOC pools and indicated knowledge gaps between PE and its regulating factors for the slow SOC pool.

关键词： boosted regression tree fresh C input recalcitrant carbon soil carbon cycling soil carbon mineralization soil moisture soil nitrogen content soil organic carbon

Drying-rewetting rather than sieving stimulates soil respiration

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Pedosphere 2022年第2期32卷 359-363页

作者： Junjie LIN weixin cheng Shuai ZHANG Biao ZHU Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir Chongqing Three Gorges UniversityChongqing 404100China Department of Environmental Studies University of CaliforniaSanta Cruz CA 95064USA Institute of Ecology College of Urban and Environmental SciencesKey Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China

Dear Editor,Soils contain the largest carbon(C) pool in terrestrial *** a small change in soil C pool may significantly influence atmospheric carbon dioxide(CO_(2)) ***,it is critical to accurately assess the response of soil C pool to global *** incubation is a frequently used method to assess soil C decomposition rate because it allows environmental variables to be under control(Unger et al.,2010;Shi and Marschner,2014).However,pre-treatments during soil sampling and processing,such as sieving and drying-rewetting,inevitably bring physical disturbances which may affect soil respiration rate(Franzluebbers,1999;Thomson et al.,2010;Curtin et al.,2014).

关键词： soil dioxide Thomson

Natural^(15)N abundance in soils and plants in relation to N cycling in a rangeland in Inner Mongolia

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Journal of Plant Ecology 2010年第3期3卷 201-207页

作者： Yuqing Xu Jicheng He weixin cheng Xuerong Xing Linghao Li National Climate Center China Meteorological Administration46 South Zhongguancun Avenue HaidianBeijing 100081China State Key Laboratory of Vegetation and Environmental Change Institute of Botanythe Chinese Academy of Sciences20 NanxincunXiangshanBeijing 100093China Energy Saving Environmental Protection and Occupational Safety and Health Research InstituteChina Academy of Railway Sciences2 DaliushuluBeijing 100081China Department of Environmental Studies University of California1156 High StreetSanta CruzCA 95064USA

Aims Natural 15N abundance provides integrated information about nitrogen(N)input,transformation and output,indirectly reflecting N cycling traits within terrestrial ***,relationships between natural 15N abundance and N cycling processes are poorly understood in ***,our primary objectives were to(i)examine the effects of grazing at varying levels of intensity on d15N of soils and plants in a semi-arid grassland;(ii)detect the relationships between d15N of soils and four major N cycling processes(***,nitrification,denitrification and ammonia volatilization);and(iii)determine whether d15N of soils can be used as an indicator of N cycling in this semi-arid *** The field experiment was conducted within the long-term(17-year)grazing enclosures in a semi-arid grassland in Inner *** grazing intensities(0.00,1.33,2.67,4.00 and 5.33 sheep ha1)were designed.d15N values of topsoils(0–10 cm),surface soils(0–2 cm)and plants were measured in *** in d15N of soils and plants between the five grazing intensities were *** of four soil N cycling processes were measured periodically during the 2005 and 2006 growing *** d15N values of topsoils were linked to the four N cycling processes to investigate their *** Findings The d15N values of topsoils(5.20–5.96&)were substantially higher than the d15N values of plants(2.51–2.93&)and surface soils(1.44–2.92&)regardless of grazing *** 15N-depleted N losses during microbial decomposition of organic matter in concert with the downward movement of residual substrate over time are the possible causes of higher d15N values in topsoils than in surface *** addition,the d15N values of topsoils were positively correlated with the d15N values of both plants and surface ***,especially the high-intensity grazing(5.33 sheep ha1),resulted in a significant decrease in d15N of surface ***,no statistically sig

关键词： d15N NH3 volatilization mineralization nitrification denitrification grazing intensity grassland

热等静压TiC/H13钢基复合材料的力学性能与合理初始粒径比

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粉末冶金材料科学与工程 2016年第2期21卷 243-248页

作者：成伟欣江勇田云中南大学深圳研究院深圳518057 中南大学材料科学与工程学院长沙410083 中南大学教育部有色金属材料重点实验室长沙410083

以H13钢粉和TiC粉末为原料,采用热等静压法制备H13钢和TiC/H13钢基复合材料,重点考察TiC粉末与H13钢粉末的初始粒径比（r/R）对复合材料的致密度、宏观硬度、微观组织及拉伸性能的影响。结果表明：直接用市售的H13钢粉和TiC粉制备的TiC/... 详细信息

以H13钢粉和TiC粉末为原料,采用热等静压法制备H13钢和TiC/H13钢基复合材料,重点考察TiC粉末与H13钢粉末的初始粒径比（r/R）对复合材料的致密度、宏观硬度、微观组织及拉伸性能的影响。结果表明：直接用市售的H13钢粉和TiC粉制备的TiC/H13钢基复合材料,其致密度和抗拉强度均比H13钢的低,分别为88.2%和544.5 MPa,硬度HRC为62.5,比H13钢的略高。通过构建简单几何关系模型及分析,推导出增强相TiC颗粒与H13钢粉的初始粒径比r/R的合理判据,

关键词：钢基复合材料 H13钢 TiC 热等静压初始粒径比

原位制备Fe(TiC)_p复合材料中增强相颗粒的组织遗传性及调控技术

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粉末冶金材料科学与工程 2016年第6期21卷 892-898页

作者：田云江勇贺涔成伟欣中南大学深圳研究院深圳518057 中南大学材料科学与工程学院长沙410083 中南大学教育部有色金属材料重点实验室长沙410083

以羰基Fe粉、Ti粉及C粉为原料,采用真空原位反应烧结法制备颗粒增强型Fe(TiC)_p复合材料。对微观组织的观察和元素分析发现,原料Ti粉对TiC增强颗粒的形貌和粒径具有较明显的遗传性。对这一组织遗传性,从反应热力学和扩散动力学方面给出... 详细信息

以羰基Fe粉、Ti粉及C粉为原料,采用真空原位反应烧结法制备颗粒增强型Fe(TiC)_p复合材料。对微观组织的观察和元素分析发现,原料Ti粉对TiC增强颗粒的形貌和粒径具有较明显的遗传性。对这一组织遗传性,从反应热力学和扩散动力学方面给出解释,并基于此认识,设计原料Ti粉的球磨细化预处理工序。经预处理后原位反应烧结材料的致密度明显提升,并能够在铁基体中形成分散度更高、尺度更细小、且近球形的TiC增强颗粒,从而使复合材料的硬度从HV99.4提高到HV152.3,抗弯强度从550 MPa提高到935 MPa。

关键词： Fe(TiC)p复合材料原位反应增强相颗粒组织遗传性预处理

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人脸识别中边缘检测器的改进

西安电子科技大学学报 1998年第2期25卷 146-151页

作者：魏立梅张永瑞谢维信程相君西安电子科技大学电子工程学院

分析了现有的人脸识别边缘检测器存在的缺陷，提出了改进的边缘检测器：高斯微分算子快速算法使计算速度提高１０倍以上；图像二值化的“或与法”大大提高了二值图像的质量．实验证明该文的边缘检测器性能优良，是复杂图像二值化的好方法．

关键词：边缘检测边缘增强图像二值化人脸识别

基于K-Means聚类算法的井下电缆双端在线局放定位方法

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电工技术 2024年第5期 88-90,93页

作者：程维新窑街煤电集团有限公司金河煤矿甘肃兰州730000

常规的电缆局放定位方法以反射信号识别与定位为主,时间同步偏差相对较大,影响最终的局放定位精准度,因此设计了基于K-Means聚类算法的井下电缆双端在线局放定位方法。该方法通过提取井下电缆双端行波模量特征,将井下电缆局放信号进行... 详细信息

常规的电缆局放定位方法以反射信号识别与定位为主,时间同步偏差相对较大,影响最终的局放定位精准度,因此设计了基于K-Means聚类算法的井下电缆双端在线局放定位方法。该方法通过提取井下电缆双端行波模量特征,将井下电缆局放信号进行相模变换,分析相应电荷气隙平衡条件,获取更加准确的双端局放位置。基于K-Means算法构造电缆在线局放定位聚类中心,将空间距离相似的电缆进行局放判断,排除异常定位数据对聚类结果的影响,从而减小定位误差。采用对比实验验证了该方法的定位精准度高,能应用于实际生活中。

关键词： K-Means聚类算法井下电缆双端在线局放定位方法

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人脸识别中基准点的选取与特征点定位

西安电子科技大学学报 1998年第1期25卷 102-106页

作者：魏立梅张永瑞谢维信程相君西安电子科技大学电子工程学院

提出了一种基准点选取的新方法，为实现不同性别人脸图像的识别开辟了一条可行之路，还提出了去除眼镜对眼域定位影响的“峰定位法”，为解决戴眼镜人脸图像的识别问题提供了一个行之有效的方法．实验表明，文中方法对特征点定位准确，... 详细信息

提出了一种基准点选取的新方法，为实现不同性别人脸图像的识别开辟了一条可行之路，还提出了去除眼镜对眼域定位影响的“峰定位法”，为解决戴眼镜人脸图像的识别问题提供了一个行之有效的方法．实验表明，文中方法对特征点定位准确，速度快．

关键词：基准点特征点人脸图像识别