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A Complex Mode Method for Wind-Induced Responses of 6-Parameter Practical Viscoelastic Damping Energy Dissipation Structures Based on the Davenport Wind Speed Spectrum北大核心CSCD 下载免费PDF全文
针对六参数实用黏弹性阻尼耗能结构,基于Davenport风速谱系列响应问题进行了系统的研究.首先,利用六参数黏弹性阻尼器的微分型本构关系,建立了耗能结构基于Davenport风速谱激励下的运动方程;然后,运用复模态法将耗能结构的运动方程由二阶微分方程转化为一阶方程,获得了耗能结构系统对风振激励响应的频域解和功率谱密度函数表达式;最后,利用数学恒等式,基于随机振动理论获得了耗能结构系统在Davenport风速谱激励下的响应和阻尼器受力的解析解.该文方法不仅考虑了结构系统在风振激励作用下全振型展开的结果,表达式较现有结果更为简便,效率及精度更高,且适用于非经典阻尼结构. 相似文献
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F. Beukers 《Journal of Number Theory》2010,130(3):660-679
In this article we discuss how close different powers of integers can be to each other. In addition we study pairs of powers of polynomials with rational coefficients which have differences of small positive degree. 相似文献
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FRIED Michael D. 《中国科学 数学(英文版)》2012,55(1):1-72
Davenport’s Problem asks:What can we expect of two polynomials,over Z,with the same ranges on almost all residue class fields? This stood out among many separated variable problems posed by Davenport,Lewis and Schinzel.By bounding the degrees,but expanding the maps and variables in Davenport’s Problem,Galois stratification enhanced the separated variable theme,solving an Ax and Kochen problem from their Artin Conjecture work.Denef and Loeser applied this to add Chow motive coefficients to previously introduced zeta functions on a diophantine statement.By restricting the variables,but leaving the degrees unbounded,we found the striking distinction between Davenport’s problem over Q,solved by applying the Branch Cycle Lemma,and its generalization over any number field,solved by using the simple group classification.This encouraged Thompson to formulate the genus 0 problem on rational function monodromy groups.Guralnick and Thompson led its solution in stages.We look at two developments since the solution of Davenport’s problem.Stemming from MacCluer’s 1967 thesis,identifying a general class of problems,including Davenport’s,as monodromy precise.R(iemann)E(xistence)T(heorem)’s role as a converse to problems generalizing Davenport’s,and Schinzel’s (on reducibility).We use these to consider:Going beyond the simple group classification to handle imprimitive groups,and what is the role of covers and correspondences in going from algebraic equations to zeta functions with Chow motive coefficients. 相似文献
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《Discrete Mathematics》2020,343(7):111888
For any sequence , the extremal function is the maximum possible length of a -sparse sequence with distinct letters that avoids . We prove that if is an alternating sequence of length , then for all and , answering a question of Wellman and Pettie (2018) and extending the result of Roselle and Stanton that for any alternation of length (Roselle and Stanton, 1971).Wellman and Pettie also asked how large must be for there to exist -block sequences of length . We answer this question by showing that the maximum possible length of an -block sequence is if and only if . We also show related results for extremal functions of forbidden 0–1 matrices with any constant number of rows and extremal functions of forbidden sequences with any constant number of distinct letters. 相似文献
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Michael Freeze 《Discrete Mathematics》2010,310(23):3373-3389
A generalization of the Davenport constant is investigated. For a finite abelian group G and a positive integer k, let denote the smallest ? such that each sequence over G of length at least ? has k disjoint non-empty zero-sum subsequences. For general G, expanding on known results, upper and lower bounds on these invariants are investigated and it is proved that the sequence is eventually an arithmetic progression with difference exp(G), and several questions arising from this fact are investigated. For elementary 2-groups, is investigated in detail; in particular, the exact values are determined for groups of rank four and five (for rank at most three they were already known). 相似文献
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Let G be a finite commutative semigroup. The Davenport constant of G is the smallest integer d such that, every sequence S of d elements in G contains a subsequence T (≠S) with the same product of S. Let
. Among other results, we determine D(R
×)−D(U(R)), where R
× is the multiplicative semigroup of R and U(R) is the group of units of R. 相似文献
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We use the Euler, Jacobi, Poincaré, and Brun matrix algorithms as well as two new algorithms to evaluate the continued fraction
expansions of two vectorsL related to two Davenport cubic formsg
1 andg
2. The Klein polyhedra ofg
1 andg
2 were calculated in another paper. Here the integer convergentsP
k
given by the cited algorithms are considered with respect to the Klein polyhedra. We also study the periods of these expansions.
It turns out that only the Jacobi and Bryuno algorithms can be regarded as satisfactory.
Translated fromMatematicheskie Zametki, Vol. 61, No. 3, pp. 339–348, March, 1997.
Translated by V. E. Nazaikinskii 相似文献
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An order-Davenport–Schinzel sequence over an -letter alphabet is one avoiding immediate repetitions and alternating subsequences with length . The main problem is to determine the maximum length of such a sequence, as a function of and . When is fixed this problem has been settled (see Agarwal, Sharir, and Shor, 1989, Nivasch, 2010 and Pettie, 2015) but when is a function of , very little is known about the extremal function of such sequences.In this paper we give a new recursive construction of Davenport–Schinzel sequences that is based on dense 0–1matrices avoiding large all-1 submatrices (aka Zarankiewicz’s Problem ). In particular, we give a simple construction of matrices containing 1s that avoid all-1 submatrices. (This result seems to be absent from the literature on Zarankiewicz’s problem, but it may be considered folklore among experts in this area [Z. Füredi, personal communication, 2017].)Our lower bounds on exhibit three qualitatively different behaviors depending on the size of relative to . When we show that grows exponentially with . When we show grows faster than any polynomial in . Finally, when , matches the trivial upper bound asymptotically, whenever is constant. 相似文献