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41.
42.
Auditory masking in three pinnipeds: aerial critical ratios and direct critical bandwidth measurements 总被引:1,自引:0,他引:1
Southall BL Schusterman RJ Kastak D 《The Journal of the Acoustical Society of America》2003,114(3):1660-1666
This study expands the limited understanding of pinniped aerial auditory masking and includes measurements at some of the relatively low frequencies predominant in many pinniped vocalizations. Behavioral techniques were used to obtain aerial critical ratios (CRs) within a hemianechoic chamber for a northern elephant seal (Mirounga angustirostris), a harbor seal (Phoca vitulina), and a California sea lion (Zalophus californianus). Simultaneous, octave-band noise maskers centered at seven test frequencies (0.2-8.0 kHz) were used to determine aerial CRs. Narrower and variable bandwidth masking noise was also used in order to obtain direct critical bandwidths (CBWs). The aerial CRs are very similar in magnitude and in frequency-specific differences (increasing gradually with test frequency) to underwater CRs for these subjects, demonstrating that pinniped cochlear processes are similar both in air and water. While, like most mammals, these pinniped subjects apparently lack specialization for enhanced detection of specific frequencies over masking noise, they consistently detect signals across a wide range of frequencies at relatively low signal-to-noise ratios. Direct CBWs are 3.2 to 14.2 times wider than estimated based on aerial CRs. The combined masking data are significant in terms of assessing aerial anthropogenic noise impacts, effective aerial communicative ranges, and amphibious aspects of pinniped cochlear mechanics. 相似文献
43.
Aldehydes react with ketenes generated from photolysis of Fischer chromium carbene complexes to generate either beta-lactones or enol ethers resulting from decarboxylation of beta-lactones. The reaction is catalyzed by tertiary amines and can occur with diastereoselectivity greater than 20:1 with DMAP as the catalyst. 相似文献
44.
Brandon J. O'Neill David H. K. Jackson Dr. Anthony J. Crisci Carrie A. Farberow Fengyuan Shi Dr. Ana C. Alba‐Rubio Dr. Junling Lu Dr. Paul J. Dietrich Dr. Xiangkui Gu Dr. Christopher L. Marshall Prof. Peter C. Stair Dr. Jeffrey W. Elam Dr. Jeffrey T. Miller Prof. Fabio H. Ribeiro Prof. Paul M. Voyles Prof. Jeffrey Greeley Prof. Manos Mavrikakis Prof. Susannah L. Scott Prof. Thomas F. Kuech Prof. James A. Dumesic 《Angewandte Chemie (International ed. in English)》2013,52(51):13824-13824
45.
46.
Brandon Carter 《General Relativity and Gravitation》2009,41(12):2873-2938
This is a reprinting of Part 1 of Brandon Carter’s lectures given at the 1972 Les Houches school on black holes, first published
in a book of proceedings of that school in 1973. The paper has been selected by the Editors of General Relativity and Gravitation
for re-publication in the Golden Oldies series of the journal. The main value of this article is a comprehensive discussion
of global properties of the Kerr solution, its maximal extension, its derivation from the separability of the Klein-Gordon
equation and, most notably, its generalisation to nonzero cosmological constant. Numerous typos of the original text are corrected
in this reprinting. The reprinted article is accompanied by an editorial note written by Niky Kamran and Andrzej Krasiński,
and by B. Carter’s brief autobiography. 相似文献
47.
Yihao Tang Malik Hassanaly Venkat Raman Brandon A. Sforzo Jerry Seitzman 《Proceedings of the Combustion Institute》2021,38(2):2589-2596
Fast and reliable high altitude re-ignition is a critical requirement for the development of alternative jet fuels (AJFs). To achieve stable combustion, a spark kernel needs to transit in a partially or fully extinguished flow to develop a flame front. Understanding the relight characteristics of the AJFs is complicated by the chaoticity of the turbulent flow and variations in the spark properties. The focus of this study is the prediction of such characteristics by high-fidelity simulations, with a specific focus on fuel composition effect on the ignition process. For this purpose, a previously developed computational framework is applied, which utilizes high-fidelity LES simulations, a hybrid tabulation approach for modeling forced ignition and detailed quantification of uncertainty resulting from initial and boundary conditions to predict ignition probability. The method is applied to two alternative fuels (named C1 and C5) and Jet-A fuel (named A2) under gaseous conditions. Results show that the mixing of kernel and fuel–air mixture is not affected by the ignition process, but chemistry effects strongly dominate ignition probability. In particular, C1 exhibits much lower ignition probability than the other two fuels, especially at lean operating conditions. More importantly, this behavior is contradictory to ignition delay experiments which predict longer delay times for C5 compared to C1. Comparisons with experiments show that the comprehensive modeling approach captures the ignition trends. Analysis of kernel trajectories in composition space shows that the variations are caused by the relative effects of kernel mixing, response to strain, and ignition properties of the fuel. 相似文献
48.
Fard A Yang JY Buckley B Wang J Chitgarha MR Zhang L Willner AE Jalali B 《Optics letters》2011,36(19):3804-3806
Optical performance monitoring of high-capacity networks is one of the enabling technologies of future reconfigurable optical switch networks. In such networks, rapid performance evaluation of data streams becomes challenging due to the use of advanced modulation formats and high data rates. The time-stretch enhanced recording oscilloscope offers a potential solution to monitoring high-rate data in a practical time scale. Here we demonstrate an architecture with a differential detection front end for simultaneous I/Q data monitoring of a 100 gigabits/s return-to-zero differential quadrature phase-shift keying signal. This demonstration shows the potential of this technology for rapid performance monitoring of high-rate optical data streams that employ advanced modulation formats. 相似文献
49.
John J. Ambrosiano Scott T. Brandon Rainald Lhner C. Richard DeVore 《Journal of computational physics》1994,110(2)
Traditional techniques for computing electromagnetic solutions in the time domain rely on finite differences. These so-called FDTD (finite-difference time-domain) methods are usually defined only on regular lattices of points and can be too restrictive for geometrically demanding problems. Great geometric flexibility can be achieved by abandoning the regular latticework of sample points and adopting an unstructured grid. An unstructured grid allows one to place the grid points anywhere one chooses, so that curved boundaries can be fit with ease and local regions in which the field gradients are steep can be selectively resolved with a fine mesh. In this paper we present a technique for solving Maxwell's equations on an unstructured grid based on the Taylor-Galerkin finite-element method. We present several numerical examples which reveal the fundamental accuracy and adaptability of the method. Although our examples are in two dimensions, the techniques and results generalize readily to 3D. 相似文献
50.
This paper presents a method for the analytical prediction of sliding motions along discontinuous boundaries in non-smooth
dynamical systems. The methodology is demonstrated through investigation of a periodically forced linear oscillator with dry
friction. The switching conditions for sliding motions in non-smooth dynamical systems are given. The generic mappings for
the friction-induced oscillator are introduced. From the generic mappings, the corresponding criteria for the sliding motions
are presented through the force product conditions. The analytical prediction of the onset and vanishing of the sliding motions
is illustrated. Finally, numerical simulations of sliding motions are carried out to verify the analytical prediction. This
analytical prediction provides an accurate prediction of sliding motions in non-smooth dynamical systems. The switching conditions
developed in this paper are expressed by the total force of the oscillator, and the nonlinearity and linearity of the spring
and viscous damping forces in the oscillator cannot change such switching conditions. Therefore, the achieved force criteria
can be applied to the other dynamical systems with nonlinear friction forces processing a C
0-discontinuity. 相似文献