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Boehmeria nivea var. strigosa (Urticaceae), a new variety from Southwest China
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作者 ZHAO Ying Richard I.MILNE +2 位作者 LI Zhipeng Amos KIPKOECH WU Zengyuan 《广西植物》 CAS CSCD 北大核心 2024年第9期1617-1624,I0001-I0006,共14页
Boehmeria nivea var.strigosa Zeng Y.Wu&Y.Zhao,a new variety of B.nivea(Urticaceae)from Southwest China,is here described based on evidence from morphology and molecular phylogeny.This new variety is mainly charact... Boehmeria nivea var.strigosa Zeng Y.Wu&Y.Zhao,a new variety of B.nivea(Urticaceae)from Southwest China,is here described based on evidence from morphology and molecular phylogeny.This new variety is mainly characterized by its green abaxial leaf blade,partly connate stipules,and densely patent strigose hairs on stems and potioles.The phylogenetic analysis based on rbc L,nrDNA and rbc L+nrDNA datasets,revealed that all individuals of B.nivea var.strigosa formed a monophyletic group.The conservation status of B.nivea var.strigosa is assessed as“Near Threatened”(NT)according to IUCN evaluation criteria.The discovery of this new variety is not only crucial for the taxonomy of ramie,but also provides reference for the exploration and utilization of ramie. 展开更多
关键词 Boehmeria nivea MORPHOLOGY molecular phylogeny new variety Southwest China YUNNAN
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Higher-order mode analysis for SOLEIL-type superconducting cavity
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作者 Xiyuan Chai Qin Li +3 位作者 Yunpeng Xu Yungai Tang Mingsheng Tan Cong-Feng Wu 《中国科学技术大学学报》 CAS CSCD 北大核心 2024年第7期56-65,55,I0003,共12页
A 499.8 MHz SOLEIL-type superconducting cavity was simulated and designed for the first time in this paper.The higher-order mode(HOM)properties of the cavity were investigated.Two kinds of coaxial HOM couplers were de... A 499.8 MHz SOLEIL-type superconducting cavity was simulated and designed for the first time in this paper.The higher-order mode(HOM)properties of the cavity were investigated.Two kinds of coaxial HOM couplers were designed.Using 4 L-type and 4 T-type HOM couplers,the longitudinal impedance and the transverse impedances were suppressed to below 3 kΩand 30 kΩ/m,respectivly.The HOM damping requirements of Hefei Advanced Light Facility(HALF)were satisfied.This paper conducted an in-depth study on the radio frequency(RF)design,multipacting optimization,and thermal analysis of these coaxial couplers.Simulation results indicated that under operating acceleration voltage,the optimized couplers does not exhibit multiplicating or thermal breakdown phenomena.The cavity has the potential to reach a higher acceleration gradient. 展开更多
关键词 HOM coupler superconducting cavity RF system multipacting thermal simulation
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人与情境交互作用理论述评 被引量:25
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作者 曾守锤 桑标 《心理科学》 CSSCI CSCD 北大核心 2005年第5期1256-1258,共3页
人与情境交互作用理论认为,人-情境系统是一个整合、复杂和动态的整体,个体是其中一个积极和有目的的部分。该理论对情境在个体功能和发展中的作用、人-情境系统发挥自身功能的原则,以及人和情境子系统的结构和过程作了详尽的分析。这... 人与情境交互作用理论认为,人-情境系统是一个整合、复杂和动态的整体,个体是其中一个积极和有目的的部分。该理论对情境在个体功能和发展中的作用、人-情境系统发挥自身功能的原则,以及人和情境子系统的结构和过程作了详尽的分析。这些理论主张对当前心理学的理论、方法和研究策略具有深远的启示意义,但也存在难以操作化的缺点。 展开更多
关键词 情境 ()系统 整体交互作用论 理论 交互作用 理论述评 个体功能 系统 理论主张
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Mitochondrial DNA Sequences Imply Anhui Musk Deer a Valid Species in Genus Moschus 被引量:13
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作者 宿兵 王应祥 王岐山 《Zoological Research》 CAS CSCD 北大核心 2001年第3期169-173,共5页
Anhui musk deer [ Moschus ( moschiferus/berezovskii ) anhuiensis ] has been a taxonomic mystery since its discovery in early 80's.In this paper,with museum samples,we sequenced the complete cytochrome b ge... Anhui musk deer [ Moschus ( moschiferus/berezovskii ) anhuiensis ] has been a taxonomic mystery since its discovery in early 80's.In this paper,with museum samples,we sequenced the complete cytochrome b gene of five Anhui musk deer.When compared with other species in Genus Moschus ,Anhui musk deer showed a rather level of sequence divergence from all the other species in this genus.The phylogenetic trees constructed by multiple methods supported the same topology,in which the monophyly of Anhui musk deer was clearly demonstrated.Therefore,our molecular data suggest a full species status for Anhui musk deer ( Moschus anhuiensis ),rather than a subspecies of either M moschiferus or M berezovskii previously suggested by morphological studies. 展开更多
关键词 Musk deer Genus Moschus Anhui musk deer Cytochrome b gene Molecular phylogeny
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Phylogenetic Relationships of the Pentatomomorpha (Hemiptera: Heteroptera) Inferred from Nuclear 18S rDNA Sequences 被引量:9
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作者 李红梅 邓日强 王珣章 《Zoological Research》 CAS CSCD 北大核心 2006年第3期307-316,共10页
Sequences from a region of the nuclear ribosomal 18S rDNA gene of approximately 1 912 base pairs (bp) were used to generate a molecular phylogeny for the Pentatomomorpha based on 53 species representing 21 putative ... Sequences from a region of the nuclear ribosomal 18S rDNA gene of approximately 1 912 base pairs (bp) were used to generate a molecular phylogeny for the Pentatomomorpha based on 53 species representing 21 putative families. Phylogenetic analyses using the most parsimony method (MP), maximum likelihood method (ML), and neighbor joining method (NJ) showed strong support that the Pentatomomorpha lineage is a monophyly and the superfamily Aradoidea is a sister group to the remainder of the Pentatomomorpha (Trichophora). The Trichophora could be divided into two clades : one clade consisted of the monophyletic superfamilies Pentatomoidea and Pyrrhocoroidea; the other was mainly the polyphyletic superfamilies Lygaeoidea, Coreoidea and Idiostoloidea. The superfamilies Lygaeoidea and Coreoidea were both polyphyletic. Within Lygaeoidea, Piesmatidae was sister to Berytidae. They formed a clade locating at the basal of the Trichophora and distantly related to the other two families Lygaeidae and Rhyparochromidae. This research suggested that 18S rDNA was a proper marker to reconstruct the phylogeny of Pentatomomorpha that was accordant to morphological studies and the research of Li et al (2005). The Pyrrhocoroidea was further divided from the Coreoidea (s./at ). It was suggested that the Piesmatidae might be assigned as a superfamily of Pentatomomorpha rather than a family in Lygaeoidea. 展开更多
关键词 Molecular phylogeny Pentatomomorpha 18 S rDNA Trichophora
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Phylogeny of Apaturinae Butterflies (Lepidoptera: Nymphalidae) Based on Mitochondrial Cytochrome OxidaseⅠ Gene 被引量:4
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作者 张敏 曹天文 +3 位作者 张睿 郭亚平 段毅豪 马恩波 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第9期812-823,共12页
The phylogenetic relationships of genera in the subfamily Apaturinae were examined using mtDNA sequence data from 1,471 bp of cytochrome oxidase subunit Ⅰ (COI). The mitochondrial COI gene from a total of 16 specie... The phylogenetic relationships of genera in the subfamily Apaturinae were examined using mtDNA sequence data from 1,471 bp of cytochrome oxidase subunit Ⅰ (COI). The mitochondrial COI gene from a total of 16 species in 11 genera were sequenced to obtain mtDNA data, along with those of 4 species obtained from GenBank, to construct the MP and the NJ trees using Athyma jina, Penthema adelma, Polyura nepenthes, and Charaxes bernardus as outgroups. The transitions at the third codon positions of the COI data set were found saturated, but they were retained for analysis, because they contain the majority of the phylogenetic information. The impacts of equal weight assumptions for all characters in the parsimonious analysis were assessed by potential alternations in clades in response to different transition/transversion weighting schemes. The results indicated four distinct major groups in Apaturinae. Moreover, several well supported and stable clades were found in the Apaturinae. The study also identified undetermined taxon groups whose positions were weakly supported and were subject to changes under different weighting schemes. Within the Apaturinae, the clustering results are approximately identical to the classical morphological classification. The mtDNA data suggest the genus Mimathyma as a monophyletic group. Lelecella limenitoides and Dilipa fenestra have close relationship with very strong support in all phylogenetic trees. It also supports the taxonomic revision of removing several species from Apatura to other genera, namely Mimathyma schrenckii, M. chevana, M. nycteis, Chitoria subcaerulea, C. fasciola, C. pallas, and Helcyra subalba. 展开更多
关键词 NYMPHALIDAE apaturinae MTDNA molecular phylogeny cytochrome oxidase gene
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Molecular Phylogeny of Bisexual Artemia Based on 16S rDNA 被引量:5
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作者 印红 关妮 付育婷 《Agricultural Science & Technology》 CAS 2011年第5期659-662,共4页
[Objective] The research aimed at investigating the taxonomic position and phylogenetic relationship of bisexual brine shrimps.[Method] 16S rDNA of three species of bisexual Artemia from China was determined;the homol... [Objective] The research aimed at investigating the taxonomic position and phylogenetic relationship of bisexual brine shrimps.[Method] 16S rDNA of three species of bisexual Artemia from China was determined;the homologous sequences between them and 11 relative species of Artemia from GenBank were compared;the molecular phylogenetic tree was constructed by Mega Microsoft using Artemiopsis stefanssoni as outgroup.[Result] Artemia persimilis was the primal group in genus Artemia;Artemia franciscana and Artemia monica were the evolved groups;Artemia urmiana,Artemia sinica and other Artemia species from China shared a close genetic relationship.[Conclusion] Based on the 16S rDNA sequence of them,the phylogenetic relationships of these bisexual Artemia species were A.persimilis→A.urmiana,A.sinica and A.tibetiana→A.tunisiana→A.monica→A.Franciscan. 展开更多
关键词 Bisexual Artemia 16S rDNA Molecular phylogeny
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Alloy gene Gibbs energy partition function and equilibrium holographic network phase diagrams of Au_3Cu-type sublattice system 被引量:3
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作者 谢佑卿 聂耀庄 +2 位作者 李小波 彭红建 刘心笔 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第1期211-240,共30页
Taking Au3Cu-type sublattice system as an example, three discoveries have been presented. First, the fourth barrier to hinder the progress of metal materials science is that today’s researchers do not understand that... Taking Au3Cu-type sublattice system as an example, three discoveries have been presented. First, the fourth barrier to hinder the progress of metal materials science is that today’s researchers do not understand that the Gibbs energy function of an alloy phase should be derived from Gibbs energy partition function constructed of alloy gene sequence and their Gibbs energy sequence. Second, the six rules for establishing alloy gene Gibbs energy partition function have been discovered, and it has been specially proved that the probabilities of structure units occupied at the Gibbs energy levels in the degeneracy factor for calculating configuration entropy should be degenerated as ones of component atoms occupied at the lattice points. Third, the main characteristics unexpected by today’s researchers are as follows. There exists a single-phase boundary curve without two-phase region coexisting by the ordered and disordered phases. The composition and temperature of the top point on the phase-boundary curve are far away from those of the critical point of the Au3Cu compound; At 0 K, the composition of the lowest point on the composition-dependent Gibbs energy curve is notably deviated from that of the Au3Cu compounds. The theoretical limit composition range of long range ordered Au3Cu-type alloys is determined by the first jumping order degree. 展开更多
关键词 Au3Cu compound Au3Cu-type sublattice system alloy gene Gibbs energy partition function equilibrium holographic network phase diagrams systematic metal materials science
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Alloy gene Gibbs energy partition function and equilibrium holographic network phase diagrams of AuCu_3-type sublattice system 被引量:3
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作者 谢佑卿 李小波 +2 位作者 刘心笔 聂耀庄 彭红建 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第11期3585-3610,共26页
Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing exp... Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing experimental phenomena of alloy phase transitions during extremely slow variation in temperature by equilibrium thinking mode and then taking erroneous knowledge of experimental phenomena as selected information for establishing Gibbs energy function and so-called equilibrium phase diagram. Second, the equilibrium holographic network phase diagrams of AuCu3-type sublattice system may be used to describe systematic correlativity of the composition?temperature-dependent alloy gene arranging structures and complete thermodynamic properties, and to be a standard for studying experimental subequilibrium order-disorder transition. Third, the equilibrium transition of each alloy is a homogeneous single-phase rather than a heterogeneous two-phase, and there exists a single-phase boundary curve without two-phase region of the ordered and disordered phases; the composition and temperature of the top point on the phase-boundary curve are far away from the ones of the critical point of the AuCu3 compound. 展开更多
关键词 AuCu3 compound AuCu3-type sublattice system alloy gene Gibbs energy partition function equilibrium holographic network phase diagram systematic metal materials science
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Phylogenetic Relationships among 12 Species of Tetrigidae (Orthoptera:Tetrigoidea) Based on Partial Sequences of 12S and 16S Ribosomal RNA 被引量:11
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作者 陈爱辉 蒋国芳 《Zoological Research》 CAS CSCD 北大核心 2004年第6期510-514,共5页
Mitochondrial 12S and 16S ribosomal RNA genes sequences were sequenced using dye-labeled terminator on an ABI 377 automated sequencer in 11 individuals and 1 species' sequences were gained from GenBank,representin... Mitochondrial 12S and 16S ribosomal RNA genes sequences were sequenced using dye-labeled terminator on an ABI 377 automated sequencer in 11 individuals and 1 species' sequences were gained from GenBank,representing 6 genera of family Tetrigidae.The collated sequences were aligned using Clustal X version 1.81 and then,the sequence variability and heredity distances based on Kimura 2-parameter model were calculated using Mega 2.1.In obtained sequences (736 bp),the average A+T content is 73.9%,ranging from 71.2% to 77.5%;the overall G+C content is 26.1%,ranging from 22.5% to 28.8%.Based on alignment of the combined sequences,185 parsimony-informative sites were revealed in 755 available base pairs.Phylogenetic trees were reconstructed using NJ,MP and ML methods with Cylindraustralia kochii as outgroup.The results indicated that the monophyletic nature of Tetrix is questioned and suggest that T.tubercarina may be given tribal rank.Our results also show that Coptltettix huanjiangensis and C.gongshanensis are the same species,i.e.Coptltettix gongshanensis Zheng,and C.huanjiangensis is the synonyms of C.gongshanensis. 展开更多
关键词 TETRIGIDAE Phylogeny 12S rRNA gene 16S rRNA gene
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Molecular Phylogeny of the Lardizabalaceae Based on TrnL-F Sequences and Combined Chloroplast Data 被引量:5
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作者 王峰 李德铢 杨俊波 《Acta Botanica Sinica》 CSCD 2002年第8期971-977,共7页
The molecular phylogeny of the Lardizabalaceae is reconstructed based on chloroplast trn L_F sequences alone and combined trn L_F and rbc L sequences. The phylogenetic topologies agree well with Qin's and... The molecular phylogeny of the Lardizabalaceae is reconstructed based on chloroplast trn L_F sequences alone and combined trn L_F and rbc L sequences. The phylogenetic topologies agree well with Qin's and Takhtajan's tribal classification in both analyses. Decaisneae and Sinofranchetieae are basal clades in the phylogenetic trees and external to all other taxa in the family. Lardizabaleae consisting of Boquila and Lardizabala are well supported in both trn L_F (100%) analysis and trn L_F and rbc L combined analysis (99%). Tribe Akebieae are strongly supported by a bootstrap value of 100% in both trn L_F analysis and trn L_F and rbc L combined analysis. However, the new genus Archakebia is nested within the genus Akebia in the trn L_F trees. In the combined trees, Archakebia is sister to Akebia with high bootstrap support. The inter_relationships among three closely related genera Parvatia , Holboellia and Stauntonia are still problematic. P. brunoniana ssp. elliptica is sister to H. latifolia in both analyses with low bootstrap support. H. parviflora is nested within the Stauntonia and sister to S. cavalerieana . Therefore, these three genera of tribe Akebieae may not be monophylytic and their generic boundary and delimitation need to be further studied, by exploring more molecular data, together with more morphological characters. 展开更多
关键词 LARDIZABALACEAE molecular phylogeny trn L_F sequences rbc L sequences
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DC—20GHz RF MEMS Switch 被引量:10
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作者 朱健 林金庭 林立强 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2001年第6期706-709,共4页
The design and fabrication of a RF MEMS switch is reported for the first time in China.The switching element consists of a thin metallic membrane,which has the metal-isolator-metal contact and a capacitive shunt switc... The design and fabrication of a RF MEMS switch is reported for the first time in China.The switching element consists of a thin metallic membrane,which has the metal-isolator-metal contact and a capacitive shunt switch as single-pole single-throw.When an electrostatic potential is applied to the membrane and the bottom electrode,the attractive electrostatic force pulls the metal membrane down onto the bottom dielectric.The switch characteristics,such as insertion loss and isolation,depend on the off and on-capacitance.The test results are as follows:the pulldown voltage is about 20V;the insertion loss is less than 0 69dB from DC to 20GHz in the up-state;the isolation is more than 13dB from 14 to 18GHz and 16dB from 18 to 20GHz in the down-state. 展开更多
关键词 MEMS RF switch WIDEBAND
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Reanalysis of the phylogenetic relationships of the Pentatomomorpha(Hemiptera: Heteroptera) based on ribosomal, Hox and mitochondrial genes 被引量:1
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作者 李敏 王艳会 +4 位作者 谢强 田晓轩 李腾 张虎芳 卜文俊 《Entomotaxonomia》 CSCD 2016年第2期81-91,共11页
Pentatomomorpha is one of the most biodiverse infraorders among the true bugs(Hemiptera: Heteroptera). Phylogenetic relationships among the superfamilies within this infraorder have been uncertain, especially for t... Pentatomomorpha is one of the most biodiverse infraorders among the true bugs(Hemiptera: Heteroptera). Phylogenetic relationships among the superfamilies within this infraorder have been uncertain, especially for the Eutrichophora. The previous studies were based on morphological characters, or just mitochondrial or nuclear genes, or only partial 18 S rDNA and COI. In this study, we used maximum likelihood(ML) and Bayesian inference(BI) based on massive molecular datasets(18S rDNA, 28 S rDNA, Hox and mitochondrial genes totaling 21 loci and 12,538 characters) to infer a robust phylogeny for this terrestrial group. Results strongly support the monophyly of all superfamilies; the superfamily status of Aradoidea and the following relationships:(Aradoidea +(Pentatomoidea +(Coreoidea +(Lygaeoidea + Pyrrhocoroidea)))) in Pentatomomorpha, and(Coreoidea +(Lygaeoidea + Pyrrhocoroidea)) in Eutrichophora. Our results suggest that sampling greater numbers of genes is an effective tool for resolving phylogenetic problems. 展开更多
关键词 taxonomy Eutrichophora molecular phylogenetics molecular datasets
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REDUCING VIBRATION WITH FRICTION-DAMPING IN HIGH-SPEED ROTOR SYSTEM 被引量:1
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作者 王黎钦 李文忠 +1 位作者 古乐 郑德志 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2007年第1期48-53,共6页
To reduce the excessive vibration of a high-speed rotor system at the critical speed, a friction damper with a flexible support structure is introduced. The mechanism of vibration reduction and support characteristics... To reduce the excessive vibration of a high-speed rotor system at the critical speed, a friction damper with a flexible support structure is introduced. The mechanism of vibration reduction and support characteristics are analyzed and a friction damper is designed. The effect on an unbalanced response is studied. Results show that the stiffness factor and the friction-damping factor of the damper are related to the cone angle and the friction factor of the inner-ring when adopting a proper structure. By changing these parameters and the Z-directional stiffness of the outer-ring, the stiffness and the damping characteristic of the damper can be varied. Introducing a friction damper into the support can reduce the stiffness and increase the damping of the support, thus decreasing the critical speed to avoid the operating speed, suppress the resonant response of a rotor system, and attenuate vibration forces to the outside. 展开更多
关键词 high-speed rotor system rolling-element bearing friction-damping vibration reduction critical speed
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PROGRESS OF GREY SYSTEM MODELS 被引量:14
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作者 刘思峰 胡明礼 +1 位作者 Forrest Jeffrey 杨英杰 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2012年第2期103-111,共9页
The progress of grey system models is reviewed, and the general grey numbers, the grey sequence op- erators and several most commonly used grey system models are introduced, such as the absolute degree of grey inciden... The progress of grey system models is reviewed, and the general grey numbers, the grey sequence op- erators and several most commonly used grey system models are introduced, such as the absolute degree of grey incidence model, the grey cluster model based on endpoint triangular whitenization functions, the grey cluster model based on center-point triangular whitenization functions, the grey prediction model of the model GM ( 1,1), and the weighted multi-attribute grey target decision model. 展开更多
关键词 grey system theory general grey numbers grey sequence operators grey system models
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Estimation of the Forces on Rubbing Rotor-Bearing System 被引量:2
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作者 黄葆华 杨建刚 高伟 《Journal of Southeast University(English Edition)》 EI CAS 1998年第2期51-55,共5页
It*ss very important to identify the load on rotor bearing system. Based on load identification in time domain, a new method combined with transfer matrix method is applied in rubbing rotor bearing system to estimat... It*ss very important to identify the load on rotor bearing system. Based on load identification in time domain, a new method combined with transfer matrix method is applied in rubbing rotor bearing system to estimate the force on rubbing rotor for the first time. Avoiding calculating the modal parameters, the outside excitation force on multi point and the distribute of internal forces on rubbing rotor bearing system can be identified by this way at the same time. Finally, the simulation is made on partial lateral rubbing rotor bearing system. For the faulty of rotor/stator rub, the point where rubbing occurs and the change of impact forces can be detected by this method in order to improve the accuracy of rotor/stator rub faulty diagnosis. 展开更多
关键词 rotor bearing system RUBBING diagnosis transfer matrix method
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COUPLED DYNAMIC CHARACTERISTICS AND CONTROL OF ROTOR-CONICAL MAGNETIC BEARING SYSTEM 被引量:1
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作者 杨静 虞烈 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2004年第3期189-194,共6页
The coupled dynamic characteristics of the conical electromagnetic bearing are presented and their definitions are given. On the basis of the analyses of the characteristics, the dynamic model of five degrees of freed... The coupled dynamic characteristics of the conical electromagnetic bearing are presented and their definitions are given. On the basis of the analyses of the characteristics, the dynamic model of five degrees of freedom (five-DOF) rotor-conical electromagnetic bearing system is made, and the influence of the coupled characteristics on the system optimal controller is analyzed. 展开更多
关键词 conical electromagnetic bearing current coupling geometry coupling optimal controller
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Applying Double Electric Fields to Avoid Deteriorating Movable Sensitive Parts in MEMS During Anodic Bonding 被引量:1
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作者 杨道虹 徐晨 沈光地 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第10期1249-1252,共4页
Anodic bonding between silicon and glass with dou bl e electric fields is presented.By this means,the damage caused by the electric f ield to the movable part during bonding can be avoided and the experiment result s ... Anodic bonding between silicon and glass with dou bl e electric fields is presented.By this means,the damage caused by the electric f ield to the movable part during bonding can be avoided and the experiment result s show that. 展开更多
关键词 micro-electronic machine system anodic bondin g double electric fields
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Modified embedded-atom interatomic potential for Co-W and Al-W systems 被引量:1
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作者 董卫平 陈铮 Byeong-Joo LEE 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第3期907-914,共8页
A semi-empirical interatomic potential formalism,the second-nearest-neighbor modified embedded-atom method(2NN MEAM),has been applied to obtaining interatomic potentials for the Co-W and Al-W binary system using previ... A semi-empirical interatomic potential formalism,the second-nearest-neighbor modified embedded-atom method(2NN MEAM),has been applied to obtaining interatomic potentials for the Co-W and Al-W binary system using previously developed MEAM potentials of Co,Al and W.The potential parameters were determined by fitting the experimental data on the enthalpy of formation,lattice parameter,melting point and elastic constants.The present potentials generally reproduce the fundamental physical properties of the Co-W and Al-W systems accurately.The lattice parameters,the enthalpy of formation,the thermal stability and the elastic constants match well with experiment and the first-principles results.The enthalpy of mixing and the enthalpy of formation and mixing of liquid are in good agreement with CALPHAD calculations.The potentials can be easily combined with already-developed MEAM potentials for binary cobalt systems and can be used to describe Co-Al-W-based multicomponent alloys,especially for interfacial properties. 展开更多
关键词 modified embedded-atom method Co-W system Al-W system atomistic simulation
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Male Reproductive System and Spermatogenesis in Homoptera(Insecta:Hemiptera) 被引量:7
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作者 田润刚 袁锋 张雅林 《Entomotaxonomia》 CSCD 北大核心 2006年第4期241-253,共13页
Morphology of the male reproductive system, chromosome behaviors during meiosis and spem tail structures in Homoptera and Heteroptera are compared in this paper. The sheathed testis is found in Fulgoroidea and Heterop... Morphology of the male reproductive system, chromosome behaviors during meiosis and spem tail structures in Homoptera and Heteroptera are compared in this paper. The sheathed testis is found in Fulgoroidea and Heteroptera, and unsheathed testis occurs in Cicadoidea, Cicadelloidea, Cercopoidea, Membracoidea, Psyloidea, Aphidoidea, Aleyrodoidea and Coccoidea. The testis also can be divide into three types by the shape of testicular follicles. The sphere-shaped type is found in Cicadoidea, Cicadelloidea, Cercopoidea, Membracoidea, Aphidoidea and Aleyrodoidea, the tube-shaped type observed in Fulgoroidea, Psyloidea and Coccoidea, and the lamella-shaped type represented by Heteroptera. It is suggested the unsheathed testis may be the primitive type in Homoptera. Meiosis can be divided into 6 type at least, i.e. 1) Cicadoid type; 2) Fulgoroid type; 3) Psyloid type; 4) Aphidoid type; 5) Aleyrodoid type; and 6) Coccoid type. At least four groups exhibit a diffuse stage during meiosis prophase l, they are Psyloidea, Fulgoroidea, Coccoidea and Heteroptera. Sperm tail structures are similar to those reported from other insects with a typical 9+9+2 axoneme except that in Aleyrodoidea and Coccoidea whose sperm tail is degenerated. 展开更多
关键词 HEMIPTERA HOMOPTERA reproductive system SPERMATOGENESIS MEIOSIS sperm structure
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