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141.
Banach frames and atomic decompositions are sequences that have basis-like properties but which need not be bases. In particular, they allow elements of a Banach space to be written as linear combinations of the frame or atomic decomposition elements in a stable manner. In this paper we prove several functional — analytic properties of these decompositions, and show how these properties apply to Gabor and wavelet systems. We first prove that frames and atomic decompositions are stable under small perturbations. This is inspired by corresponding classical perturbation results for bases, including the Paley — Wiener basis stability criteria and the perturbation theorem el kato. We introduce new and weaker conditions which ensure the desired stability. We then prove quality properties of atomic decompositions and consider some consequences for Hilbert frames. Finally, we demonstrate how our results apply in the practical case of Gabor systems in weighted L2 spaces. Such systems can form atomic decompositions for L2w(IR), but cannot form Hilbert frames but L2w(IR) unless the weight is trivial. 相似文献
142.
转动系统的相对论性分析力学理论 总被引:20,自引:3,他引:17
本文讨论了转动相对论力学理论,主要是建立转动系统的相对论性分析力学理论·构造转动系统的相对论性广义动能函数Tr=∑ni=1I0iΓi2(1-1-θ·2i/Γi2)和广义加速度能量函数Sr=12∑ni=1Ii(θ·i·θ¨i)2Γi2-θ·2i+θ¨2i,给出其Hamilton原理和三种不同形式的D′Alembert原理;对于完整约束系统,建立了转动系统的相对论性Lagrange方程、Nielsen方程、Appel方程和Hamilton正则方程;对于非完整约束系统,建立了转动系统的相对论性Routh方程、Чаплыгин方程、Nielsen方程和Appel方程;并给出转动系统的相对论性Noether守恒律 相似文献
143.
Rolf Vonhoff 《Mathematische Nachrichten》1998,193(1):199-210
In the paper, a new method of constructing asymptotic solutions of differential equations on manifolds with singularities is presented. This method allows not only to widen essentially the space of asymptotics but also to obtain explicit formulas for asymptotic expansions, in particular, in the case when in a neighborhood of a singular point there exist strata of different dimensions. 相似文献
144.
Uncertainty about the nature and significance of nonlinearities and the manner in which dynamics affect future realizations makes model specification the most difficult aspect of modeling dynamic systems. By interpreting several popular fishery models as subcases of a nesting dynamic Taylor series approximation, we isolate the specification differences between these models in a way that accounts for commonalities. On the argument that the differences due to alternative nonlinear forms are likely to be small compared to more mundane considerations such as delay difference and general dynamic lag specification, we propose an alternative model that uses the terms from the first order approximation common to all models combined with a data-based determination of the appropriate lags using the methods of state space time series analysis. Finally, the success of the alternative models is judged in an application to Pacific halibut data. 相似文献
145.
Solveig Linko 《Accreditation and quality assurance》2002,7(2):55-59
Internal audits inherently effect quality improvement, and concrete results can be expected by careful planning. As audits
should improve the quality system in situ, the development of audits should not be neglected. ISO/IEC 17025 describes the
objectives of internal audits and management reviews in more detail compared to the former standards EN 45001 and ISO/IEC
Guide 25, although the main features are unchanged. This addresses continuous surveillance of the current practice. A brief
questionnaire on vertical audits was distributed to 74 of 120 employees at a Finnish private medical laboratory, Medix Laboratories
Ltd. A positive feed-back was received from the current management of audits. However, the study revealed that continuous
supervision of audits is needed. Many employees were not willing to perform audits if they had no previous experience. Additionally,
audits performed at the workbench were not considered as the best possible for fruitful discussions.
Received: 20 February 2001 Accepted: 30 November 2001 相似文献
146.
主要研究相互粒子系统中概率测度的负相关.我们得到判定概率测度是负相关的一个充分必要条件.最后证明了具有负相关的概率测度的线性组合及乘积测度仍是负相关的. 相似文献
147.
We have studied the vibrational frequencies and atom displacements of one-dimensional systems formed by combinations of Thue-Morse and Rudin-Shapiro quasi-regular stackings with periodic ones. The materials are described by nearest-neighbor force constants and the corresponding atom masses. These systems exhibit differences in the frequency spectrum as compared to the original simple quasi-regular generations and periodic structures. The most important feature is the presence of separate confinement of the atom displacements in one of the parts forming the total composite structure for different frequency ranges, thus acting as a kind of phononic cavity. 相似文献
148.
利用指数二分性理论和泛函分析方法,我们研究了自治奇摄动系统的同,异宿轨道的存在性,给出了高维奇摄动系统从退化系统分支出同异宿轨道的Mel-nikov型函数。 相似文献
149.
M. Reuhl P. Nielaba K. Binder 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(2):225-232
,Static and dynamic properties of the Potts model on the simple cubic lattice with nearest neighbor -interaction are obtained from Monte Carlo simulations in a temperature range where full thermal equilibrium still can be
achieved (). For a lattice size L
= 16, in this range finite size effects are still negligible, but the data for the spin glass susceptibility agree with previous
extrapolations based on finite size scaling of very small lattices. While the static properties are compatible with a zero
temperature transition, they certainly do not prove it. Unlike the Ising spin glass, the decay of the time-dependent order
parameter is compatible with a simple Kohlrausch function, , while a power law prefactor cannot be distinguished. The Kohlrausch exponent y
(
T
) decreases from at [0pt] to at [0pt] however. The relaxation time is compatible with the exponential divergence postulated by McMillan for spin glasses at their lower critical dimension,
but the exponent that can be extracted still differs significantly from the theoretical value, . Thus the present results support the conclusion that the Potts spin glass in d
= 3 dimensions differs qualitatively from the Ising spin glass.
Received: 8 October 1997 / Accepted: 27 November 1997 相似文献
150.
4-Aminophthalimide Derivatives as Environment-Sensitive Probes 总被引:2,自引:0,他引:2
The potential of 4-aminophthalimide (AP) and its derivatives as fluorescence probes for organized media is highlighted. The fluorescence response of AP, as measured from the position of the fluorescence maximum, fluorescence intensity and lifetime, is highly sensitive to the polarity of the medium. The sensitivity of the fluorescence parameters is further enhanced due to the involvement of the emitting intramolecular charge transfer state in hydrogen bonding interaction with the solvent molecules containing hydroxyl groups. It is shown that the microheterogeneous environments of organized media such as cyclodextrins and micelles can be very conveniently monitored using this probe. The results of the investigations carried out employing AP and its derivatives as fluorescence probe molecules in these media clearly suggest that a combination of the hydrophobic interaction with the host media and hydrogen bonding interaction with the solvent molecules determine the location of the fluorophore, which in all cases is found to be the interfacial region separating the nonpolar core of the micelle or the cyclodextrin cavity and the polar aqueous environment. Guidelines for the design of probes of this class of systems for the nonpolar core region of the micelles are provided and possible ways to increase the sensitivity of the fluorescence response of the systems are suggested. 相似文献