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1.
Cloud Makasu 《Sequential Analysis》2013,32(4):498-501
Abstract This article concerns a characterization of a vector-valued optimal stopping problem with only two reward functions. Under certain conditions, we give an explicit characterization of the Pareto stopping times for the present problem via a scalar-valued double optimal stopping problem. The latter problem is a natural extension of the classical McDonald-Siegel optimal stopping problem with one stopping rule. 相似文献
2.
The substrate temperature achieved during physical vapor deposition significantly affects the properties and phases of thin films. An Isoflux ICM-10 Dual Target Inverted Cylindrical Magnetron Sputtering system is used to deposit low temperature alpha-phase alumina, for which an experimentally determined substrate temperature is desired. Constraints inherent to the Isoflux system limit the use of a thermocouple. Instead, a pressure vessel containing numerous samples of temperature indicating liquids is placed in the chamber during operation. These indicator paints are observed upon completion of the deposition process to record the substrate temperature. Measurements indicate a temperature range of 343 °C to 399 °C for our alpha-phase alumina films deposited at a pressure of 0.27 Pa (2 mTorr), a substrate bias of − 35 V, and a power of 5 kW. Theoretical heat transfer calculations support the experimental measurements. A parametric investigation showed that the removal of the − 35 V substrate bias decreases the substrate temperatures by approximately 35 °C and that the substrate temperature increases about 50 °C for each additional kilowatt of power in the range of 1 kW to 6 kW. 相似文献
3.
Drachman B. Cloud M. Nyquist D.P. 《Antennas and Propagation, IEEE Transactions on》1989,37(3):403-406
It is shown that the fast Fourier transform (FFT) combines naturally with Simpson's rule for Sommerfeld-type integral computation. The principal advantage of using the FFT is that a single subroutine call yields a set of sample values of an integral (i.e. the integral for various values of an integrand parameter). Such samples could be useful in themselves. In other applications Sommerfeld integrals represent Green's functions nested within other spatial integrals, so samples from the FFT might be useful in approximating the outernested integral. Several examples are provided to illustrate the process 相似文献
4.
A mixed potential formulation is given for electrical fields in layered environments. Contributions to the field from charges are identified explicitly through a scalar Green's function for layered media. The outcome is a computationally expedient Sommerfeld integral representation 相似文献
5.
The increase in the popularity of breast feeding and utilization of child care arrangements are having a major effect on the epidemiology of cytomegalovirus infections. The impact is greater for women of upper socioeconomic background who send their toddlers to day-care centers and for day-care workers. If primary cytomegalovirus infections occur during pregnancy it is logical to anticipate more cases of severe congenital infections. 相似文献
6.
Appelbaum A. Cloud P. Daly E. Parad L. 《Antennas and Propagation, IEEE Transactions on》1972,20(5):582-588
A recently developed phased-array feed configuration offering significant advantages over the conventional space, corporate, and series feed techniques is described. This technique, referred to as the "flat feed," allows power division for monopulse sum and difference pattern illumination functions in a feed depth of less than a half-wavelength with low loss. The technique used to extract energy from the power divider, which consists in part of a radial transmission line, results, in its simplest configuration, in a circular grid of antenna elements. Relations governing the circular grid array geometry design are derived which relate the angular locations of attenuated grating lobes to the spacing between the rings of radiating elements. ExperimentalS -band hardware, built to prove the feed technique, is described. It includes a multimode launcher with measured coupling between circular wavegulde sum (TM_{01} ) and difference (TE_{11} ) modes of less than -37 dB; a seven-ring 1:195 radial power divider measured across a 10-percent band to have insertion loss of 0.1 dB and rms phase and amplitude deviations of less than3.5deg and 0.47 dB; a 144-element array whose measured sum and difference beam radiation patterns are compared with calculated patterns for scan angles out to60deg and whose sum port VSWR, measured across a 10-percent band, was under 1.8:1 with the array steered to broadside, and under 1.5:1 for other scan angles out to60deg . 相似文献
7.
A pipe whip restraint utilizing the dissipative capacity of a plastically deforming element has been developed. The transient dynamic behavior of the pipe and the restraint is studied using a discrete mathematical model consisting of nonlinear spring, mass, and damper elements. The forcing function is a fluid dynamic transient resulting from a break in a main steam line which is part of a Westinghouse pressurized water reactor (PWR) nuclear plant. An extensive parametric study shows the relative influence of gap, restraint support rigidity, the elastic and plastic behavior of pipe, break opening time, and finally the change in restraint mass on the behavior of the pipe restraint system. 相似文献
8.
ABSTRACT A modified system for pneumatic injection in graphite furnace is proposed. The pneumatic injection yield (volume of really injected liquid/aspirated volume) for a commercial nebuliser is lower than 10%; the proposed modifications make it quantitative allowing a spectacular lowering of sample consumption. 相似文献
9.
An energy-based method is utilized for calculating elastic-plastic strains and stresses near fatigue crack tip in specimens of Merlon polycarbonate. The stress redistribution caused by the plastic yielding around the crack tip is taken into account so that theoretical crack tip strain is improved. The estimated values of crack tip strain based on an energy density approach are compared with experimental results obtained from an embedded grid moire technique and embedded strain gages. Large-scale yielding seems to dominate near the crack tip. In fact, the measured strain is in agreement with the elastic solution, which means, in reality, only small-scale yielding takes place near the crack tip. The strain in the mid-plane (plane strain) is found to be higher than in the surface plane (plane stress). The experimental and theoretical results are in good agreement. 相似文献
10.
Carew Tania Giovannetti; Lamar Melissa; Cloud Blaine S.; Grossman Murray; Libon David J. 《Canadian Metallurgical Quarterly》1997,11(3):400
The underlying mechanisms for impaired output on letter (F, A, and S) and category (e.g., animal) word list generation (WLG) tasks in subcortical ischemic vascular dementia (IVD) were investigated. Normal control (NC) and Alzheimer's disease (AD) participants were also studied. IVD and NC participants performed better on category than letter WLG tasks, whereas the opposite was observed among AD participants. IVD participants produced fewer responses than AD participants on letter WLG tasks, but there was no difference between AD and IVD participants on the "animal" WLG task. AD participants scored lower than IVD and NC participants on animal WLG indexes measuring semantic knowledge. There were few differences between IVD and NC participants. The reduced output on the animal WLG task for IVD participants is consistent with search-retrieval deficits. The reduced output of AD participants may be caused by degraded semantic knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献