Results 31 to 40 of about 8,458 (116)

无定河黄土区降水和产沙的相关性及其时空变异

open access: yesShuitu Baochi Xuebao, 2020
通过泰森多边形加权变差系数法研究了黄河中游无定河流域黄土区降水和侵蚀产沙的空间变异规律,并用线性回归分析探究两者空间变异性的相关性。以黄河主要泥沙来源区之-的无定河流域为例,分析了该流域黄土区1959—2015年水土保持措施综合治理前后降水和侵蚀产沙的时空变异规律,所选用的降水特征为汛期降水(Pflood)和汛期降雨侵蚀力(Rflood),用产沙模数(SSY)表示该流域产沙量的多少。结果表明:(1)在水土流失治理前(1959—1970年),该地区降水特征与产沙模数在时间上的增减变化趋势-致 ...
张萍, 郑明国, 蔡强国, 马小晴
doaj  

Microstructure Engineering Toward High Cost‐Effective Nd–Fe–B Sintered Magnets: A Review

open access: yesRare Metals, Volume 45, Issue 7, July 2026.
ABSTRACT Nd–Fe–B sintered magnets, critical for enhancing electromechanical conversion efficiency and operational stability in wind turbines and electric vehicle drives, are prized for their outstanding coercivity, high remanence, and superior maximum energy product.
Dongmin Zhang   +5 more
wiley   +1 more source

科尔沁沙地沙质草场土壤水分对干旱和降雨响应的空间变异性

open access: yesShuitu Baochi Xuebao, 2005
采用地统计学的方法,研究了科尔沁沙地沙质草场土壤含水量对干旱和降雨响应的空间变异规律。结果表明,干旱时沙质草场表层(0~20cm)、亚表层(20~40cm)土壤含水量可很好地拟合成球状模型和指数模型,在1~2.26m,1~6.63m的中等尺度范围内表现出很高的空间自相关性,空间自相关度分别为0.92,0.87.分维数均表现出较弱的空间依赖性.分别为1.99,1.94,两层土壤含水量变异特征差异小,土壤水分的空间变异性强,破碎化程度高。降雨后沙质草场土壤表层 ...
左小安 赵学勇 赵哈林 李玉霖 移小勇 黄刚
doaj   +2 more sources

In Situ Investigation on the Roles of Microstructural Characteristics in Fatigue Anisotropy and Crack Propagation of LPBF–IN718 Alloy

open access: yesRare Metals, Volume 45, Issue 7, July 2026.
ABSTRACT Laser powder bed fusion (LPBF) of Inconel 718 alloy inevitably introduces pronounced microstructural anisotropy, typified by columnar grains and robust crystallographic texture. This results in direction‐dependent fatigue behavior, raising critical reliability concerns for high‐stakes aerospace applications.
Zhifang Shi   +9 more
wiley   +1 more source

Spatial distribution of duration of possible sunshine based on DEM in mountain area(基于DEM的山地可照时间的空间分布)

open access: yesZhejiang Daxue xuebao. Lixue ban, 2007
以山区高空间分辨率的DEM数据为主要数据源,在提取纬度、坡度、坡向等相应的地形要素栅格数据的基础上,利用GIS技术对山区可照时间的空间分布进行了模拟,实现了山区可照时间空间分布规律的可视化表达,分析了山区可照时间的空间分布特征,对于山区的农业、林业和生态环境等方面的研究具有重要意义.
LIJun(李军), HUANGJing-feng(黄敬峰)
doaj   +1 more source

Heterointerfaces and Sulfur Vacancies in MXene/MoS2@C for Boosted Ultra‐Broadband Electromagnetic Wave Absorption and Infrared Stealth Response

open access: yesRare Metals, Volume 45, Issue 7, July 2026.
ABSTRACT Ti3C2Tx MXene shows significant potential in the field of electromagnetic wave absorption; however, the wave absorption performance was hindered due to the impedance mismatch, which was caused by its inherent high dielectric constant. In this work, Ti3C2Tx MXene co‐assembled with molybdenum disulfide nanosheets and carbon coating layers (MXene/
Hualong Yu   +11 more
wiley   +1 more source

Influence of Alkaline Earth Barium on the Microstructure, Corrosion Behavior, and Cytocompatibility of Biodegradable Zinc

open access: yesRare Metals, Volume 45, Issue 7, July 2026.
ABSTRACT Biodegradable Zn‐based alloys are promising candidates for temporary implants, yet excessive Zn2+ release during degradation may induce cytotoxicity and adverse tissue responses. In this study, Zn‐xBa alloys (x = 0.1 wt%, 0.5 wt%, 1.0 wt% and 3.0 wt%) were developed to achieve controlled corrosion behaviors with improved biocompatibility.
Liu‐Dang Fang   +9 more
wiley   +1 more source

典型SF6气体绝缘缺陷局部放电脉冲的Gabor特征识别

open access: yesGaoya dianqi, 2015
局部放电脉冲具有非平稳特性,采用联合时频域分析比常规的单域分析更能诊断放电的特征。因此,针对现场GIS可能存在的缺陷类型,设计了针板、悬浮和空穴的缺陷模型,提取其在工频电压下局部放电脉冲的Gabor分布特征,并采用BP人工神经网络对特征参数进行训练和测试;同时通过现场110 kV GIS的缺陷的局部放电实测,对放电脉冲Gabor特征分析的有效性进行了研究。结果表明,放电脉冲的时频特征图谱能够得到有效提取,为放电评估提供参考,特征参数的训练识别率和测试识别率较高,利于放电类型的识别。
任重
doaj  

土壤侵蚀时空变异及其与环境因子的时空关系

open access: yesShuitu Baochi Xuebao, 2002
土壤侵蚀的时空变异是指在一定的景观内 ,不同时间、不同地点的土地侵蚀特征存在明显的差异性和多样性。土壤侵蚀的时空变异是多重尺度上的植被、土地利用、气象 (降雨 )、地形和土壤等多因子综合作用的结果 ,但是就某一具体地区而言存在重点尺度和主控因子 ,土壤侵蚀的重点尺度与主控因子的时空关系因时间、空间和尺度而异 ...
邱扬 傅伯杰 王勇
doaj   +2 more sources

基于空间电场特征的复合绝缘子运行状态识别方法研究

open access: yesDianci bileiqi
恶劣气象条件地区的污闪事故仍时有发生,因此在对复合绝缘子污闪发展过程空间电场信号进行了测量的基础上,提出基于空间电场信号的污秽绝缘子运行状态识别方法。研究结果表明:污秽闪络整个放电过程可分为干燥区、湿润区、局部放电区三个区段;空间电场波形特征不因盐密的改变而变化,且空间电场时域波形的区段特征明显。最后提出基于空间电场的峰值、有效值和标准差,并结合温度、相对湿度组成五个特征量作为运行状态分类的特征量;案例结果表明本研究提出的空间电场特征的识别方法对污秽绝缘子运行状态可以进行可靠的分类,正确率为95 ...
韩学春, 宋恒东, 陈轩, 冯欣欣
doaj  

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