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991.
Indhumathi Kulandhaisamy Dinesh Babu Rajendran Malathi Kanagasabai Gunasekaran Gurusamy Balaji Moorthy Jithila V. George 《Waves in Random and Complex Media》2017,27(1):38-46
In this paper, an analog multiband phase shifter using slotline configuration is proposed. To implement the design, a pair of modified Split Ring Resonator (SRR) is employed. The periodic property of SRR provides multiband characteristics, whether the coupling slot gives the phase variations over the bands. The operation is well explained with an equivalent circuit model and its characteristics have been studied both in simulation and measurement. The prototype operates in 1.77–2.16, 3.5–3.97, 5.08–5.33, 6.43–6.93, and 8.01–8.59 GHz frequency bands which can be utilized for GSM, GPS, WLAN, C-band, and X-band applications, respectively. 相似文献
992.
George A. Klouda James J. Filliben 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):997-1003
The NIST low-level beta counting system is designed to capture digitally and timestamp each event for retrospective analysis. As a result, low and stable backgrounds are achieved and lead to extremely low detection and quantification limits for measuring, e.g., 14C of atmospheric gases and aerosol. The objective here is to explore the variability of the background count rate (counts per day) of several small (1 mL) freshly-assembled gas proportional counters (GPCs). The mean is 14.0 day?1 with 95 % confidence limits 11.2–16.8 day?1. The raw count per day data was non-normal and so a Log transformation was applied to achieve normality and to rigorously compute normal tolerance limits. Back in the original space such (95 % confidence, 95 % coverage) tolerance limits were 2.5–47.8 day?1. These limits are taken as acceptance criteria for any GPCs assembled in the future. 相似文献
993.
Robert L. Coldwell George P. Lasche 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):655-662
Cambio is a software application well-suited for analysis of high-resolution nuclear spectral data in which the critical information resides in well-masked peaks or in which the data are sparse and good statistics cannot be obtained. The statistical uncertainty in the results is reported in terms of standard deviations. In the practical use of any analysis application, it is important to have a good understanding of the accuracy of the reported statistical uncertainties in the results. The authors report the results of an experiment that provides a quantitative measure of the accuracy of the reported uncertainties in analyses using Cambio. Ten calibration sources ranging in activity from 25 to 450 kBq were placed 20.5 m from a bare, 100 % relative-efficient high-purity germanium detector. Peaks in these sources occur from 20 to 2,800 keV. Data were accumulated for 128 h to create a parent spectrum from which 1024 8-hour statistically-equivalent daughter spectra were created by random sampling of the parent spectrum data. The parent spectrum was analyzed by fitting parameters which included an underlying continuum, a background of natural peaks adjusted by detector efficiency and material attenuation, and a foreground of the ten sources adjusted by detector efficiency only. Each of the daughter spectra were then analyzed starting with the parameters of the fit to the parent spectrum and then minimizing Chi-square with respect to changes in these parameters. The standard deviations of the estimated activities of the sources from all 1024 spectra were then calculated and compared to the reported statistical uncertainty in the activities and peak areas of the sources. 相似文献
994.
995.
996.
Soo-Jin Park George G. Chase Kwang-Un Jeong Hak Yong Kim 《Journal of Sol-Gel Science and Technology》2010,54(2):188-194
Flexible mats of titania fibers are prepared by calcination of electrospun polyvinylpyrrolidone fibers containing titanium
isopropoxide precursor. Structural investigation of the calcinated nanofibers by X-ray diffraction (XRD) and electron diffraction
(ED) combined with the morphologies by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show
the titania fibers, with an average diameter of 180 nm, were comprised of anatase and rutile crystals. The mechanical, chemical
and thermal properties of the titania fiber mats are further investigated by the techniques of Instron mechanical tester,
thermogravimetric analyzer (TGA), and Fourier transform infrared spectroscopy (FT-IR). The titania fiber mat prepared in this
method exhibited a significant flexibility with 461 MPa Young’s modulus. 相似文献
997.
998.
George Ellis 《Foundations of Physics》2018,48(10):1226-1245
The present day standard cosmological model is a great theoretical achievement. This chapter surveys the main themes that have arisen and issues that are still oustanding. 相似文献
999.
Minas P. Georgiadis Violetta Constantinou-Kokotou George Kokotos 《Journal of carbohydrate chemistry》2013,32(5):739-748
ABSTRACT 6′-N derivatives of neamine with alanine, phenylalanine and lysine were synthesized either using an active esters method in one step under controlled conditions, or using a mixed anhydride method after blocking every functional group of neamine and leaving the 6′-amino group free to react. Similarly N,N′-diamino acid and monoamino acid derivatives of 2-deoxystreptamine were synthesized. 相似文献
1000.