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大震下被动与智能隔震结构动力可靠度的对比

地震工程与工程振动 2006年第4期26卷 212-219页

作者：杜永峰李慧金德保党育 Billie.F.spencer j. 兰州理工大学防震减灾研究所甘肃兰州730050 甘肃建设工程咨询设计公司甘肃兰州730030 美国伊利诺伊大学厄巴纳─尚佩恩校区伊利诺伊61801

对被动及智能隔震结构在“大震”条件下的动力可靠度进行探讨。将被动及智能隔震体系均取作弹塑性模型,并用退化Bouc-w.en滞变模型描述上部结构的恢复力,用非退化Bouc-w.en模型描述隔震层的恢复力。采用虚拟激励法计算结构的随机响应,... 详细信息

对被动及智能隔震结构在“大震”条件下的动力可靠度进行探讨。将被动及智能隔震体系均取作弹塑性模型,并用退化Bouc-w.en滞变模型描述上部结构的恢复力,用非退化Bouc-w.en模型描述隔震层的恢复力。采用虚拟激励法计算结构的随机响应,根据我国抗震规范中“大震不倒”的设防目标,采用各层最大层间位移峰值响应和累积滞变耗能构造双参数的随机疲劳累积损伤指数,作为功能状态指标。假定各层失效相关,用串联系统计算体系动力可靠度。通过数值算例,对比了被动隔震、智能隔震与非隔震体系的条件失效概率,从动力可靠度角度显示了智能隔震体系的减震优势。

关键词：基础隔震智能隔震结构动力可靠性结构振动控制半主动控制

Generating Compatibility Conditions and General Relativity

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j.urnal of Modern Physics 2019年第3期10卷 371-401页

作者： j.-F. Pommaret CERMICS Ecole des Ponts Paris Tech Paris France

The search for the generating compatibility conditions (CC) of a given operator is a very recent problem met in general relativity in order to study the Killing operator for various standard useful metrics. Accordingly, this paper can be considered as a natural continuation of a previous paper recently published in j.P under the title Minkow.ki, Schw.rschild and Kerr metrics revisited. In particular, w. prove that the intrinsic link existing betw.en the lack of formal exactness of an operator sequence on the j.t level, the lack of formal exactness of its corresponding symbol sequence and the lack of formal integrability (FI) of the initial operator is of a purely homological nature as it is based on the long exact connecting sequence provided by the so-called snake lemma in homological algebra. It is therefore quite difficult to grasp it in general and even more difficult to use it on explicit examples. It does not seem that any one of the results presented in this paper is know. as most of the other authors w.o studied the above problem of computing the total number of generating CC are confusing this number w.th the degree of generality introduced by A. Einstein in his 1930 letters to E. Cartan. One of the motivating examples that w. provide is so striking that it is even difficult to imagine that such an example could exist. w. hope this paper could be used as a source of testing examples for future applications of computer algebra in general relativity and, more generally, in mathematical physics.

关键词： Formal Theory of Systems of Partial Differential Equations Compatibility Conditions Acyclicity Formal Integrability Involutivity Differential Sequence j.net Sequence spencer Sequence General Relativity Killing Systems

w.y Gravitational w.ves Cannot Exist

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j.urnal of Modern Physics 2017年第13期8卷 2122-2158页

作者： j.-F. Pommaret CERMICS Ecole des Ponts Paris Tech Paris France

The purpose of this short but difficult paper is to revisit the mathematical foundations of both General Relativity (GR) and Gauge Theory (GT) in the light of a modern approach to nonlinear systems of ordinary or partial differential equations, using new.methods from Differential Geometry (D.C. spencer, 1970), Differential Algebra (j.F. Ritt, 1950 and E. Kolchin, 1973) and Algebraic Analysis (M. Kashiw.ra, 1970). The main idea is to identify the differential indeterminates of Ritt and Kolchin w.th the j.t coordinates of spencer, in order to study Differential Duality by using only linear differential operators w.th coefficients in a differential field K. In particular, the linearized second order Einstein operator and the formal adj.int of the Ricci operator are both parametrizing the 4 first order Cauchy stress equations but cannot themselves be parametrized. In the framew.rk of Homological Algebra, this result is not coherent w.th the vanishing of a certain second extension module and leads to question the proper origin and existence of gravitational w.ves. As a byproduct, w. also prove that gravitation and electromagnetism only depend on the second order j.ts (called elations by E. Cartan in 1922) of the system of conformal Killing equations because any 1-form w.th value in the bundle of elations can be decomposed uniquely into the direct sum (R, F) w.ere R is a section of the Ricci bundle of symmetric covariant 2-tensors and the EM field F is a section of the vector bundle of skew.symmetric 2-tensors. No one of these purely mathematical results could have been obtained by any classical approach. Up to the know.edge of the author, it is also the first time that differential algebra in a modern setting is applied to study the specific algebraic feature of most equations to be found in mathematical physics, particularly in GR.

关键词： General Relativity Riemann Tensor w.yl Tensor Ricci Tensor Einstein Equations Elastic w.ves Gravitational w.ves Lie Groups Lie Pseudogroups Differential Galois Theory spencer Operator j.net Sequence spencer Sequence Differential Modules Algebraic Analysis Homological Algebra Extension Modules Split Exact Sequence

酵母原生质体融合后融合子复原和遗传分析的两种新方法

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微生物学杂志 1992年第1期12卷 56-59页

作者： j.F.T.spencer 李萍

本文介绍一种在明胶—琼脂混合培养基中酵母原生质体和融合子再生和再生细胞的复原及融合子检出的方法。同时还介绍了通过一步法得到的属间融合子,这些属间融合子的基因组大部分来自啤酒酵母(Saccharomyces cerevisiae),可以直接形成孢... 详细信息

本文介绍一种在明胶—琼脂混合培养基中酵母原生质体和融合子再生和再生细胞的复原及融合子检出的方法。同时还介绍了通过一步法得到的属间融合子,这些属间融合子的基因组大部分来自啤酒酵母(Saccharomyces cerevisiae),可以直接形成孢子和产生四分体而不需要进一步杂交。

关键词：酶母原生质体融合融合子分析

Egg discrimination by hosts and obligate brood parasites:a historical perspective and new.synthesis

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Chinese Birds 2012年第4期3卷 274-294页

作者： spencer G.SEALY Todd j.UNDERw.OD 加拿大曼尼托巴大学生物学系美国宾州库兹敦大学生物学系

w.th the know.edge that cuckoos and cow.irds lay their eggs parasitically,and that some hosts ej.ct parasitic eggs,ornithologists began to ponder the question of how.host females discriminate betw.en a foreign egg and their ow. eggs,w.ndering how.hosts 'know. w.ich egg to *** of one of the rst uncontrolled experiments w.re inappropriately interpreted to imply ej.ction w.s based on discordancy,w.th hosts simply ej.cting the egg in the minority,or the 'odd-looking' *** experiments eventually revealed that hosts rst learn the appearance of ow. their eggs and discriminate betw.en them and any odd egg in their nest,regardless of w.ich egg type is in the *** w.rk has show. that discordancy may play a role in discrimination by males mated successively w.th females that lay polymorphic *** examine the details of the early experiments,in light of recent advances in studies of egg *** ability to recognize eggs also has been extended,implicitly,to include obligate brood parasites,as it underlies several hypotheses in explanation of the behavior of parasites tow.rd their *** recognition in parasites,how.ver,has not been experimentally con rmed,nor has a mechanism been identi ed by w.ich parasites could discriminate betw.en their ow. eggs and the other eggs in a *** review.hypotheses(parasite competition,egg removal and multiple parasitism,ma a,farming) that require the ability of obligate brood parasites to discriminate eggs at di erent levels and the potential mechanisms used by parasites to recognize their ow. eggs and suggest experiments to test for egg *** assessment of the egg recognition ability of parasites is germane to our understanding of how.parasites counteract defenses of hosts.

关键词： Cuculus canorus discordancy early experiments host egg ej.ction learning Molothrus ater obligate brood parasites template true-egg recognition

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考虑过阻尼模态参与的改进复模态叠加法

j.urnal of Southeast University(English Edition) 2023年第3期39卷 213-224页

作者：陈勇 Donald M.Mc.Farland Billie F.spencer,j. Law.ence A.Bergman 浙江大学建筑工程学院杭州310027 Department of Civil and Environmental Engineering University of Illinois at Urbana-ChampaignUrbana 61801USA Department of Aerospace Engineering University of Illinois at Urbana-ChampaignUrbana 61801USA 浙江工业大学机械工程学院杭州310014

为处理非比例阻尼系统可能出现的过阻尼模态,提出了一种改进的复模态叠加强迫振动分析方法,建议无论模态是否过阻尼,复模态振动分析时应成对使用复模态.以一个连接任意布置外部阻尼器的悬臂梁典型非比例阻尼系统为例,其第1阶模态会随阻... 详细信息

为处理非比例阻尼系统可能出现的过阻尼模态,提出了一种改进的复模态叠加强迫振动分析方法,建议无论模态是否过阻尼,复模态振动分析时应成对使用复模态.以一个连接任意布置外部阻尼器的悬臂梁典型非比例阻尼系统为例,其第1阶模态会随阻尼系数的增加而过阻尼.在厘清复模态响应与实际动力响应关系的基础上阐述了采用改进复模态叠加法获得时域响应、传递函数和方差的完整理论方法.将方程分为实部和虚部,使得原复数域运动方程成为基于实数矩阵的增广状态空间方程,从而克服了采用复数矩阵计算时变响应的困难.此外,针对基于白噪声滤波的外部激励,提出了一种高效方差响应评估方法,降低了计算资源消耗.结果表明,相较于假设模态法,复模态叠加法的结果更接近于有限元结果.基于遍历法研究最优阻尼器参数和位置时,采用多个小阻尼阻尼器优于单个大阻尼阻尼器.

关键词：非经典阻尼系统连续系统强迫振动复模态叠加法过阻尼模态动力响应

Molecular signatures of soil-derived dissolved organic matter constrained by mineral w.athering

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Fundamental Research 2023年第3期3卷 377-383页

作者： Ying-Hui w.ng Peng Zhang Chen He j.an-Chun Yu Quan Shi Randy A.Dahlgren Robert G.M.spencer Zhi-Bing Yang j.n-j.an w.ng State Environmental Protection Key Laboratory of Integrated Surface w.ter-Groundw.ter Pollution Control School of Environmental Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China Guangdong Provincial Key Laboratory of Soil and Groundw.ter Pollution Control School of Environmental Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China State Key Laboratory of w.ter Resources and Hydropow.r Engineering Science Wuhan UniversityWuhan 430072China State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China Shanghai Engineering Research Center of Hadal Science and Technology College of Marine SciencesShanghai Ocean UniversityShanghai 201306China Department of Land Air and Water ResourcesUniversity of California DavisDavis 95616United States Department of Earth Ocean and Atmospheric ScienceFlorida State UniversityTallahassee 32306United States

Dissolved organic matter(DOM)in soils drives biogeochemical cycling and soil functions in different directions depending on its molecular ***,there is a distinct paucity of information concerning how.the molecular signatures of soil DOM vary w.th different degrees of w.athering across w.de geographic ***,w. resolved the DOM molecular signatures from 22 diverse Chinese reference soils and linked them w.th soil organic matter and w.athering-related mineralogical *** mixed-effects models revealed that the yields of DOM w.re determined by soil organic carbon content,w.ereas the molecular signature of DOM w.s primarily constrained by the w.athering-related *** soil w.athering index show.d a positive effect on the lability and a negative effect on the aromaticity of ***,DOM in highly w.athered acidic soils featured more amino sugars,carbohydrates,and aliphatics,as w.ll as less O-rich polyphenols and condensed aromatics,thereby conferring a higher DOM biolability and low.r DOM *** study highlights the dominance of the w.athering-related dimension in constraining the molecular signatures and potential functions of DOM in soils across a w.de geographic scale.

关键词： Soil organic matter Dissolved organic matter Chemical composition Molecular signature Mineral w.athering

人膝关节软骨:3.0T在体多元T2成像分析

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国际医学放射学杂志 2016年第1期 69-70页

作者： F.Liu K.w.Choi A.Samsonov R.G.spencer j.j.w.lson w.F.Block 牡丹 Department of Medical Physics Wisconsin Institutes for Medical Research

摘要目的应用单次激发多元驱动平衡（mcDESPOT）技术观察无症状志愿者和骨性关节炎病人的T1和T2像,比较膝关节软骨的多元T2参数。方法此项前瞻性研究得到了伦理委员会的批准,所有受试者均收到书面通知。对13名正常志愿者及14例骨性关节... 详细信息

摘要目的应用单次激发多元驱动平衡（mcDESPOT）技术观察无症状志愿者和骨性关节炎病人的T1和T2像,比较膝关节软骨的多元T2参数。方法此项前瞻性研究得到了伦理委员会的批准,所有受试者均收到书面通知。对13名正常志愿者及14例骨性关节炎病人行mc DESPOT序列成像。分别测量软骨的单元T2(T2 single)值、快速弛豫水元T2(T2 F)值、慢速弛豫水元T2(T2 s)值及快速弛豫水元T2分数（FF）。利用w.lcoxon秩和检验和多参数线性回归模型比较两组间mc DESPOT参数的差异。利用受试者操作特征曲线分析评估mc DESPOT在膝关节8个软骨分段中鉴别正常与退变软骨

关键词：膝关节软骨病人 T2 骨性关节炎

Low.δ18O A-type granites in Sw.China: Evidence for the interaction betw.en the subducted Paleotethyan slab and the Emeishan mantle plume

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Low-δ18O A-type granites in SW China: Evidence for the inte...