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71.
72.
We describe the operational principle of and experimentally demonstrate a narrowband, wavelength-tunable polarization monitor based on a fiber acousto-optic tunable filter. Two orthogonally vibrating acoustic waves are used to create a variable polarizer that can be used to measure the state of polarization of an incident narrowband light source. The accuracy of the polarization monitor is measured at two different wavelengths in reference to a commercial polarimeter and is shown to be within 5%. 相似文献
73.
The problem of minimising the dynamic response of an anisotropic rectangular plate with minimum possible expenditure of force is presented for various cases of boundary conditions. The plate has a principal direction of anisotropy rotated at an arbitrary angle relative to the coordinate axes. This orientation angle has been taken as an optimisation design parameter. The control problem is formulated as an optimisation problem by using a performance index, which comprises a weight sum of the control objective and penalty function of the control force. The explicit solutions for the closed-loop distributed control function is obtained by means of Liapunov-Bellman theory. To assess the present solution, numerical results are presented to illustrate the effect of anisotropy ratio, orientation angle, aspect ratio and boundary conditions on the control process. 相似文献
74.
In this article, we consider the drift parameter estimation problem for the nonergodic Ornstein-Uhlenbeck process defined as d X_t= θX_tdt + dG_t, t ≥ 0 with an unknown parameter θ 0, where G is a Gaussian process. We assume that the process {X_t, t ≥ 0} is observed at discrete time instants t_1 = ?_n, ···, t_n= n?_n, and we construct two least squares type estimators ■ and ■ for θ on the basis of the discrete observations {X_(t_i), i = 1, ···, n}as n →∞. Then, we provide sufficient conditions, based on properties of G, which ensure that ■ and ■ are strongly consistent and the sequences n?n~(1/2)(■-θ) and n?n~(1/2)(■-θ)are tight. Our approach offers an elementary proof of [11], which studied the case when G is a fractional Brownian motion with Hurst parameter H ∈(1/2, 1). As such, our results extend the recent findings by [11] to the case of general Hurst parameter H ∈(0, 1). We also apply our approach to study subfractional Ornstein-Uhlenbeck and bifractional Ornstein-Uhlenbeck processes. 相似文献
75.
76.
Rajendra Merla Arjuna Naseem Muhammad Joy Muthipeedika Nibin Sunil K. Sajith Ayyiliath Meleveetil Howari Fares Nazzal Yousef Xavier Cijo Alshammari Mohammed B. Haridas Karickal Raman 《Molecular diversity》2022,26(3):1761-1767
Molecular Diversity - We herein report a modified methodology for the synthesis of some oxadiazoles linked to amides under mild conditions. The developed protocol using NMI-TfCl has been found to... 相似文献
77.
Rawhi Al‐Far Basem Fares Ali 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(4):m137-m139
In the title compound, (C7H9Br2N2)2[SnBr6], the cations and centrosymmetric anions are stacked in alternating layers that show no significant intermolecular interactions within each stack. Extensive cation⋯[SnBr6]2− interactions are found, represented by short Br⋯Br interactions, along with different Br⋯HN (pyridine and amine) and weaker Br⋯HCH2 hydrogen‐bonding motifs. 相似文献
78.
Kazuki Fukushima Daniel J. Coady Gavin O. Jones Hamid A. Almegren Abdullah M. Alabdulrahman Fares D. Alsewailem Hans W. Horn Julia E. Rice James L. Hedrick 《Journal of polymer science. Part A, Polymer chemistry》2013,51(7):1606-1611
This article describes studies on the catalytic activity of several nitrogen‐based organic catalysts for the depolymerization of poly(ethylene terephthalate) (PET), in which a few cyclic amidines work more effectively than a potent, bifunctional guanidine‐based catalyst 1,5,7‐triazabicyclo‐[4,4,0]‐dec‐5‐ene (TBD) in the presence of short chain diols that play a role in activation of carbonyl groups through hydrogen bonding. Further studies prove that the catalytic efficiency at the above specific conditions depends only on the extent of activation of a hydroxyl group rather than simply the pKa of the bases. For glycolysis with excess short‐chain alkanediols, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene is the best catalyst. In contrast, TBD shows outstanding catalytic activity in depolymerizations of PET with mono‐alcohols and longer‐chain diols. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
79.
We generalize notions and results obtained by Amice for regular compact subsets S of a local field K and extended by Bhargava to general compact subsets of K. Considering any ultrametric valued field K and subsets S that are regular in a generalized sense (but not necessarily compact), we show that they still have strong properties such as having v-orderings ${\{a_n\}_{n\geq0}}$ which satisfy a generalized Legendre formula, which are very well ordered and well distributed sequences in the sense of Helsmoortel and which remain v-orderings when a finite number of the initial terms of the sequence are deleted. 相似文献
80.
Saadi Berri Djamel Maouche Fares Zerarga Youcef Medkour 《Physica B: Condensed Matter》2012,407(17):3328-3334
We preformed first-principle calculations for the structural, electronic, elastic and magnetic properties of Cu2GdIn, Ag2GdIn and Au2GdIn using the full-potential linearized augmented plane wave (FP-LAPW) scheme within the generalized gradient approximation by Wu and Cohen (GGA-WC), GGA+U, the local spin density approximation (LSDA) and LSDA+U. The lattice parameters, the bulk modulus and its pressure derivative and the elastic constants were determined. Also, we present the band structures and the densities of states. The electronic structures of the ferromagnetic configuration for Heusler compounds (X2GdIn) have a metallic character. The magnetic moments were mostly contributed by the rare-earth Gd 4f ion. 相似文献