检索结果-南通市图书馆

铈对Fe-Cr-Ni-Nb-Ti-Al-W合金持久寿命及晶界析出相的影响

在线全文

学校读者我要写书评

暂无评论

钢铁研究学报 2007年第4期19卷 51-53页

作者：周顺兵武汉钢铁(集体)公司技术中心湖北武汉430080

研究了稀土元素铈对铁基合金Fe-Cr-Ni-Nb-Ti-Al-W晶界析出相的数量、形貌、分布的影响及其与持久寿命的关系。结果表明:铈含量较低时,晶界析出相主要是大片状相及少量颗粒相;当铈含量增加时,晶界中颗粒相数量明显增加,片状相减少,且析... 详细信息

研究了稀土元素铈对铁基合金Fe-Cr-Ni-Nb-Ti-Al-W晶界析出相的数量、形貌、分布的影响及其与持久寿命的关系。结果表明:铈含量较低时,晶界析出相主要是大片状相及少量颗粒相;当铈含量增加时,晶界中颗粒相数量明显增加,片状相减少,且析出相分布较均匀,当铈含量过高时,晶界中析出大量片状相及颗粒相,且析出相总量增加。这些析出相的数量、形貌以及分布等特征的变化规律与合金持久寿命的变化规律一致。

关键词：铁基合金铈晶界相持久寿命

Two new species from Sulawesi and Borneo facilitate phylogeny and taxonomic revision of Engelhardia(Juglandaceae)

在线全文

学校读者我要写书评

暂无评论

Plant Diversity 2022年第6期44卷 552-564页

作者： Hong-Hu Meng Can-Yu Zhang Shook Ling Low Lang Li Jian-Yong Shen Nurainas Yu Zhang Pei-Han Huang Shi-shun zhou Yun-Hong Tan Jie Li Plant Phylogenetics and Conservation Group Center for Integrative ConservationXishuangbanna Tropical Botanical GardenChinese Academy of SciencesKunming 650223YunnanChina Yunnan Normal University Kunming 650500YunnanChina Bonn University Botanic Gardens Meckenheimer Allee 171D-53115 BonnGermany The Center for Gardening and Horticulture Xishuangbanna Tropical Botanical GardenChinese Academy of Sciences Mengla 666303YunnanChina Department of Biology Faculty of Math.&Nat.Sci.Andalas UniversityPadang 25163West SumatraIndonesia Southeast Asia Biodiversity Research Institute Chinese Academy of SciencesNay Pyi Taw 05282Myanmar Center of Conservation Biology Core Botanical GardensChinese Academy of SciencesMengla 666303YunnanChina University of Chinese Academy of Science 100049BeijingChina

Engelhardia,a genus of Juglandaceae(the walnut family),is endemic to tropical and subtropical *** rich Cenozoic fossil records and distinctive morphological characters of the living plants have been used to explore the evolutionary history and geographic distribution of ***,the taxonomy of this genus has been suffered from a lack of in-depth investigation and good specimens across its distribution *** delimitation of Engelhardia was defined with seven species in 2020,but detailed information on the circumscription of the species still remains poorly *** this study,two new species are described from Sulawesi and Borneo,Engelhardia anminiana and *** also revised and reconstructed the phylogeny within Engelhardia using morphological,molecular(plastid and ribosomal),and distribution *** sampled 787 individuals in 80 populations,and all the samples were genotyped using plastid regions,trnS-trnG,rps16,trnL-trnF,psbA-trnH,and rpl32-trnL;one ribosomal region,nuclear ribosomal internal transcribed spacer(nrITS).The all datasets were used to reconstruct the phylogenetic ***,the molecular analyses were combined for 738 sheets of specimens with 15 morphological characteristics to further explore the morphological clusters of *** analysis using morphological data confirmed the delimitation of nine Engelhardia ***,phylogenetic analysis based on molecular data(i.e.,plastid and ribosomal)supported the monophyly of Engelhardia and generated phylogenetic trees that included ***,***,***,***,***,***,***,*** and the varieties of ***(i.e.,*** ***,*** ***,*** ***,and *** ***).Our comprehensive taxonomic revision of Engelhardia will provide an insight into understanding the plant diversity in tropical and subtropical Asia.

关键词： Engelhardia Taxonomic notes Morphological clustering Phylogeny Distribution

Towards the meV limit of the effective neutrino mass in neutrinoless double-beta decays

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2020年第3期44卷 1-11页

作者： Jun Cao Guo-yuan Huang Yu-Feng Li Yifang Wang Liang-Jian Wen Zhi-zhong Xing Zhen-hua Zhao shun zhou Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Physics Liaoning Normal UniversityDalian 116029China

We emphasize that it is extremely important for future neutrinoless double-beta(0νββ)decay experiments to reach the sensitivity to the effective neutrino mass|mββ|≈1 *** such a sensitivity,it is highly possible to discover the signals of 0νββ *** no signal is observed at this sensitivity level,then either neutrinos are Dirac particles or stringent constraints can be placed on their Majorana *** this paper,assuming the sensitivity of|mββ|≈1 meV for future 0νββ decay experiments and the precisions on neutrion oscillation parameters after the JUNO experiment,we fully explore the constrained regions of the lightest neutrino mass m1 and two Majorana-type CP-violating phases{ρ,σ}.Several important conclusions in the case of normal neutrino mass ordering can be ***,the lightest neutrino mass is severely constrained to a narrow range m1∈[0.7,8]meV,which together with the precision measurements of neutrino mass-squared differences from oscillation experiments completely determines the neutrino mass spectrum m2∈[8.6,11.7]meV ing phases is limited to ρ∈[130°,230°],which cannot be obtained from any other realistic ***,the sum of three neutrino masses is found to beΣ≡m1+m2+m3∈[59.2,72.6]meV,while the effective neutrino mass for beta decays turns out to be mβ≡(|Ue1|2m1^2+|Ue2|2m2^2+|Ue3|2m3^2)1/2∈[8.9,12.6]*** observations clearly set up the roadmap for future non-oscillation neutrino experiments aiming to solve the fundamental problems in neutrino physics.

关键词： neutrinoless double-beta decays absolute neutrino masses Majorana CP phases

在线全文

学校读者我要写书评

暂无评论

当政治成为美国青年的“精神鸦片”

文化纵横 2024年第6期 112-121,M0004页

作者：周顺上海政法学院政府管理学院

一群二十出头的年轻人挥舞长枪,在人群中高喊:“忏悔吧……下地狱……XX必遭诅咒……XX必胜!”这是在伊朗或阿富汗?不,这是2016年总统大选前夕在美国威斯康星州的某次政治集会上。4年后,2020年美国总统大选,“Z世代”(95后)投票率升至5... 详细信息

一群二十出头的年轻人挥舞长枪,在人群中高喊:“忏悔吧……下地狱……XX必遭诅咒……XX必胜!”这是在伊朗或阿富汗?不,这是2016年总统大选前夕在美国威斯康星州的某次政治集会上。4年后,2020年美国总统大选,“Z世代”(95后)投票率升至53%,成为美国有史以来总统大选投票率最高、政治参与最活跃的青年人群。

关键词：政治宗派主义美国青年

维普期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

砂的静力加卸载试验和应力释放模型研究

岩土力学 2009年第9期30卷 2667-2673,2685页

作者：庄丽周顺华同济大学道路与交通工程教育部重点实验室上海200092

采用室内静力模型试验研究了某种石英砂的加卸载和应力释放特性,对比了在砝码加卸载条件下圆筒玻璃容器和矩形铁箱容器中砂中不同位置处的应力变化,明确了砂的加卸载应力变化规律,并在此基础上提出了针对砂土的摩擦型散粒体材料的应力... 详细信息

采用室内静力模型试验研究了某种石英砂的加卸载和应力释放特性,对比了在砝码加卸载条件下圆筒玻璃容器和矩形铁箱容器中砂中不同位置处的应力变化,明确了砂的加卸载应力变化规律,并在此基础上提出了针对砂土的摩擦型散粒体材料的应力释放模型。研究表明:砂中应力在加载阶段呈线性增加;而在卸载初期时应力无变化或减小量远小于卸去荷载,卸载后期砂中应力先是慢慢释放,之后在某一级卸载时突然快速释放,有较明显的分界点。分析认为,砂中加卸载规律不同的主要原因在于砂中的内摩擦作用,当卸去的荷载"作用"大于砂中内摩擦阻力时,才会产生应力释放。应力释放与否和释放大小不仅与内摩擦阻力大小有关,还与卸载水平和卸载前的应力状态有关。

关键词：砂土摩擦阻力加卸载应力释放

在线全文

学校读者我要写书评

暂无评论

组合畸变对某型发动机稳定性的影响

航空动力学报 2006年第6期21卷 1085-1091页

作者：黄顺洲胡骏南京航空航天大学能源与动力学院南京210016

压力和温度组合畸变对某涡轮风扇发动机稳定性影响的数值研究表明,该发动机的进口临界压力畸变强度和临界温度畸变强度分别为8.82%和8.60%,风扇的压力畸变敏感系数为2.608,高压压气机的温度畸变敏感系数为2.442。压力畸变和温度畸变的... 详细信息

压力和温度组合畸变对某涡轮风扇发动机稳定性影响的数值研究表明,该发动机的进口临界压力畸变强度和临界温度畸变强度分别为8.82%和8.60%,风扇的压力畸变敏感系数为2.608,高压压气机的温度畸变敏感系数为2.442。压力畸变和温度畸变的相对大小,决定了组合畸变对风扇或压气机稳定性影响的严重程度。压力畸变的相对最大强度峰值出现在风扇截面时,风扇首先失稳,反之则高压压气机首先失稳。组合畸变对发动机稳定性的影响,不是压力畸变和温度畸变单独影响的简单相加,而是一种非常复杂的非线性关系。

关键词：航空航天推进系统压力畸变温度畸变组合畸变发动机稳定性

在线全文

学校读者我要写书评

暂无评论

基于经验模态分解的宽带阵列DBF研究

压电与声光 2012年第4期34卷 627-630页

作者：杨明周顺南京电讯技术研究所江苏南京210007

已有研究对宽带阵列信号的子带分解处理中子带划分是固定的,各子带内信号数分布不均衡。该文研究了子带自适应划分的模态域宽带自适应阵列算法,提出将经验模态分解(EMD)融合于线性约束最小方差(LCMV)算法中,EMD把多分量信号自适应地分... 详细信息

已有研究对宽带阵列信号的子带分解处理中子带划分是固定的,各子带内信号数分布不均衡。该文研究了子带自适应划分的模态域宽带自适应阵列算法,提出将经验模态分解(EMD)融合于线性约束最小方差(LCMV)算法中,EMD把多分量信号自适应地分解成多阶内蕴模态函数(IMF),突出了信号的局部瞬间特征,两者结合既满足了LCMV的窄带信号要求又充分发挥了EMD自适应的特点,解决了阵元数目受到严格限制时,宽带阵列处理自由度不足、抗干扰性能下降的问题,在强干扰环境和各信号强度相差较大时也能有效检测出较弱信号。与基于FFT的子带分割相比,无需预先划分模态函数的频段,阵元数目受限时增加了处理自由度。仿真表明3阵元强干扰条件下改善增益11dB。

关键词：模态域线性约束最小方差经验模态分解宽带自适应阵列

Design and performance assessment of a time-varying channel simulator for high-mobility satellite navigation scenarios

在线全文

学校读者我要写书评

暂无评论

Design and performance assessment of a time-varying channel ...

第十四届中国卫星导航年会

作者： shun zhou Shiyun Yu Wei Shi Yongyang Hu The Sixty-Third Research Institute National University of Defense Technology

With the development of high-mobility satellite navigation systems such as LEO satellite navigation enhancement system,the ability of traditional fixed channel models to simulate channel characteristics has been widely *** work focuses on the background theory,time-varying emulator design,and performance assessment application for the necessity of a channel simulator to enable the propagation modeling from LEO satellite to mobile receiver in the high-mobility satellite navigation *** concept of satellite Doppler effect,separation of satellite Doppler shift,and local Doppler shift are discussed in this work,along with the sampling criteria for time-varying channel *** time-varying simulator based on the model of the time-varying satellite navigation channel is provided,and it is used to assess the tracking loop performance of the navigation software *** results show that the rapidly updating time-varying channel will subject the receiver to severe fluctuations and may possibly result in the tracking loop losing *** general,the rapidly timevarying channel scenario is more challenging to track and produce stable output than the general multipath channel scenario.

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

GNSS多径信道模拟的聚类稀疏拟合方案

国防科技大学学报 2023年第5期45卷 87-94页

作者：周顺欧钢唐小妹国防科技大学电子科学学院湖南长沙410073 国防科技大学第六十三研究所江苏南京210007

针对全球导航卫星系统(global navigation satellite system,GNSS)信道模拟计算量大、硬件资源开销大,不利于实时性能评估和实际工程应用的挑战,提出一种GNSS多径信道模拟的聚类稀疏拟合方案。利用基于K中心聚类信道冲击响应(channel im... 详细信息

针对全球导航卫星系统(global navigation satellite system,GNSS)信道模拟计算量大、硬件资源开销大,不利于实时性能评估和实际工程应用的挑战,提出一种GNSS多径信道模拟的聚类稀疏拟合方案。利用基于K中心聚类信道冲击响应(channel impulse response,CIR)参数萃取的稀疏拟合方法,得到等效精简CIR参数,再以稀疏抽头延迟线结构来实现信道模拟。所提方法在保持多径误差条件下,通过较少抽头数量的抽头延迟线结构滤波器拟合原始GNSS多径信道模型,可以大为简化GNSS信道模型仿真复杂度,而无须庞大的硬件资源。仿真结果表明,通过对参考信道模型生成的信道CIR参数进行稀疏拟合,所提出的方案和方法具有良好的效果。

关键词：卫星导航多径信道模拟 K中心聚类抽头延迟线