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排序方式: 共有89条查询结果,搜索用时 140 毫秒
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In general correlated models, in addition to the usual adiabatic component with a spectral index n(ad1) there is another adiabatic component with a spectral index n(ad2) generated by entropy perturbation during inflation. We extend the analysis of a correlated mixture of adiabatic and isocurvature cosmic microwave background fluctuations of the Wilkinson Microwave Anisotropy Probe (WMAP) group, who set the two adiabatic spectral indices equal. Allowing n(ad1) and n(ad2) to vary independently we find that the WMAP data favor models where the two adiabatic components have opposite spectral tilts. Using the WMAP data only, the 2sigma upper bound for the isocurvature fraction f(iso) of the initial power spectrum at k(0)=0.05 Mpc(-1) increases somewhat, e.g., from 0.76 of n(ad2)=n(ad1) models to 0.84 with a prior n(iso)<1.84 for the isocurvature spectral index. 相似文献
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Marco?BarchiesiEmail author Vesa?Julin 《Calculus of Variations and Partial Differential Equations》2017,56(3):80
We provide a sharp quantitative version of the Gaussian concentration inequality: for every \(r>0\), the difference between the measure of the r-enlargement of a given set and the r-enlargement of a half-space controls the square of the measure of the symmetric difference between the set and a suitable half-space. We also prove a similar estimate in the Euclidean setting for the enlargement with a general convex set. This is equivalent to the stability of the Brunn–Minkowski inequality for the Minkowski sum between a convex set and a generic one. 相似文献
55.
Lehtonen HM Penttinen H Rauhala J Välimäki V 《The Journal of the Acoustical Society of America》2007,122(3):1787
This paper describes the main features of the sustain-pedal effect in the piano through signal analysis and presents an algorithm for simulating the effect. The sustain pedal is found to increase the decay time of partials in the middle range of the keyboard, but this effect is not observed in the case of the bass and treble tones. The amplitude beating characteristics of piano tones are measured with and without the sustain pedal engaged, and amplitude envelopes of partial overtone decay are estimated and displayed. It is found that the usage of the sustain pedal introduces interesting distortions of the two-stage decay. The string register response was investigated by removing partials from recorded tones; it was observed that as the string register is free to vibrate, the amount of sympathetic vibrations is increased. The synthesis algorithm, which simulates the string register, is based on 12 string models that correspond to the lowest tones of the piano. The algorithm has been tested with recorded piano tones without the sustain pedal. The objective and subjective results show that the algorithm is able to approximately reproduce the main features of the sustain-pedal effect. 相似文献
56.
Arja Sarpola Heikki Hellman Vesa Hietapelto Jorma Jalonen Jukka Jokela Jaakko Rämö Jaakko Saukkoriipi 《Polyhedron》2007
Hydrolysis and speciation of aluminium sulfate octadecahydrate Al2(SO4)3·18H2O was studied by electrospray time of flight mass spectrometry (ESI TOF MS). Several novel polymeric species were determined. Highly charged polymers, characterized by other methods, such as the Keggin cation [Al13O4(OH)24(H2O)12]7+ and the octameric aluminium hydroxide cluster [Al8(OH)14(H2O)18](SO4)5 16H2O, were found using ESI-MS as the anions [Al13O4(OH)25(SO4)4]2− and [Al8O(OH)14(SO4)5(H2O)4]2−. All the main species identified contained sulfate or hydrogen sulfate. The compositions of the determined ions mimicked those of several stable mineral forms. 相似文献
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Hänninen V Korpinen M Ren Q Hinde R Halonen L 《The journal of physical chemistry. A》2011,115(11):2332-2339
We employ ab initio calculations of van der Waals complexes to study the potential energy parameters (C(6) coefficients) of van der Waals interactions for modeling of the adsorption of silver clusters on the graphite surface. Electronic structure calculations of the (Ag(2))(2), Ag(2)-H(2), and Ag(2)-C(6)H(6) complexes are performed using a coupled-cluster approach that includes single, double, and perturbative triple excitations (CCSD(T)), M?ller-Plesset second-order perturbation theory (MP2), and spin-component-scaled MP2 (SCS-MP2) methods. Using the atom pair approximation, the C(6) coefficients for silver-silver, silver-hydrogen, and silver-carbon atom systems are obtained after subtracting the energies of quadrupole-quadrupole interactions from the total electronic energy. 相似文献
58.
Hellman H Laitinen RS Kaila L Jalonen J Hietapelto V Jokela J Sarpola A Rämö J 《Journal of mass spectrometry : JMS》2006,41(11):1421-1429
The hydrolysis reactions of FeCl3 in 0.1 mM aqueous solutions were monitored by electrospray ionisation time-of-flight mass spectrometry (ESI-ToF-MS). In contrast to the other ionisation techniques, electrospray ionisation provides information on the composition of the elemental cores even in water and salt cluster ions. Therefore, the technique facilitates detection of the bonding of the chloride ions in the oxo-hydroxo-iron cores. A variety of mononuclear and polynuclear iron-oxohydroxo-chloride complexes were characterised from the cationic and anionic mass spectra of iron(III) solutions. Oxidation and reduction reactions of iron, as well as competition between OH- and Cl- ions within one iron core, were also observed. 相似文献
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Scott N. Armstrong Michael G. Crandall Vesa Julin Charles K. Smart 《Archive for Rational Mechanics and Analysis》2011,200(2):405-443
We show that an absolutely minimizing function with respect to a convex Hamiltonian \({H : \mathbb{R}^{n} \rightarrow \mathbb{R}}\) is uniquely determined by its boundary values under minimal assumptions on H. Along the way, we extend the known equivalences between comparison with cones, convexity criteria, and absolutely minimizing properties, to this generality. These results perfect a long development in the uniqueness/existence theory of the archetypal problem of the calculus of variations in L∞. 相似文献