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Chunsheng Lu Robert Danzer Franz Dieter Fischer 《Journal of the American Ceramic Society》2002,85(6):1640-1642
The influence of threshold stress on the estimation of the Weibull statistics is discussed in terms of the Akaike information criterion. Numerical simulations show that, if sample data are limited in number and threshold stress is not too large, the two-parameter Weibull distribution is still a preferred choice. For example, the fit of strength data of glass and ceramics to the two- and three-parameter Weibull distributions is compared. 相似文献
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The k-nearest-neighbour (kNN) algorithm is widely applied for the estimation of forest attributes using remote sensing data. It requires a large amount of reference data to achieve satisfactory results. Usually, the number of available reference plots for the kNN-prediction is limited by the size of the area covered by a terrestrial reference inventory and remotely sensed imagery collected from one overflight. The applicability of kNN could be enhanced if adjacent images of different acquisition dates could be used in the same estimation procedure. Relative radiometric calibration is a prerequisite for this. This study focuses on two empirical calibration methods. They are tested on adjacent LANDSAT TM scenes in Austria. The first, quite conventional one is based on radiometric control points in the overlap area of two images and on the determination of transformation parameters by linear regression. The other, recently developed method exploits the kNN-cross-validation procedure. Performance and applicability of both methods as well as the impact of phenology are discussed. 相似文献
25.
Galen R. Hatfield Beili Li Willis B. Hammond Franz Reidinger John Yamanis 《Journal of Materials Science》1990,25(9):4032-4035
Lanthanum silicon nitride (LaSi3N5) powder has been prepared under the relatively mild conditions of 1400 ° C and 1 atm nitrogen. Chemical, X-ray diffraction, solid state nuclear magnetic resonance spectra and morphological information on this powder is presented. The X-ray diffraction data and previously published information have been used to develop a more complete specification of the unit cell dimensions.29Si magic-angle spinning nuclear magnetic resonance spectra of LaSi3N5 show two chemical shifts at –64.5 and –56.5 p.p.m. These shifts reflect two electronically different types of silicon which have been attributed to the effects of quadrupolar139La nuclei and their spatial arrangements around silicon atoms. 相似文献
26.
U. Schfißler Franz Ledl 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1989,189(2):138-140
Summary The title compound has been synthesized by a novel route fromN
-trifluoroacetyl lysine methyl ester and 2,9-dimethyldeca-2,8-diene-4,7-dione. Transformation of the pyrrole substituents and easy cleavage of protecting groups yields the compound in samples of high purity.
Synthese der 2-Amino-6-(2-formyl-5-hydroxymethyl-l-pyrrolyl)-hexansäure
Zusammenfassung Die Titelverbindung wird auf einem neuen Weg ausN -Trifluoracetyllysinmethylester und 2,9-Dimethyldeca-2,8-dien-4,7-dion synthetisiert. Nach Umwandlung der Pyrrolsubstituenten und Abspaltung der Schutzgruppen unter milden Bedingungen erhält man die Titelverbindung in hoher Reinheit.相似文献
27.
Water vapour is soluted in liquid CaO-Al2O3-slags as OH?-ion. To determine the diffusion coefficient a capillary technique is used. Roughly 5 cm long platinum capillaries filled with liquid slag are equilibrated at 1500 and 1600 °C and bar different times and then are quenched in liquid D2O. By dividing these capillaries into roughly 3 mm long segments enough sample substance is won to obtain FT-IR spectra of the OH-band. From measurement of the integral extinction of the OH-band and OH?-concentration profile through the capillary is obtained. FT-IR-spectroscopy is very suitable for this capillary technique because it needs only very little sample substance. 相似文献
28.
Hans Michael Egon Pabst Franz Ledl und Hans-Dieter Belitz 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1985,181(5):386-390
Summary In addition to the mono- and dipyrrolidinohexosereductones described recently (Z Lebensm Unters Forsch (1984) 178:356) two further bittertasting compounds were isolated from heated mixtures of proline and sucrose (molar ratio 3: 1, 190 °C, 30 min) and also synthesized, namely 2,3-bis-(1-pyrrolidinyl)2-cyclopenten-l-one and 2,3-bis(1-pyrrolidinyl)-5methyliden-2-cyclopenten-l-one. The recognition thresholds (mmol/1) are 0.15–0.25 and 0.06–0.12 respectively. Both compounds have a burning bitter taste character. From a maltose-proline reaction mixture 2--glucosyl-5-hydroxy-5-methyl-4-piperidinyl-2-cyclopenten-1-one was isolated. When the dihydroxypyranone VI was heated with proline, 2,5-dihydroxy-5-methyl-4-prohnyl-2-cyclopenten-1-one and the cyclopent(b)azepinones XI and XII were among the compounds formed. These compounds also have a bitter taste character.Zusammenfassung Zusätzlich zu den kürzlich beschriebenen Mono- and Dipyrrolidinohexosereduktionen (Z Lebensm Unters Forsch (1984) 178:356) wurden zwei weitere bittere Verbindungen aus erhitzten Mischungen von Prolin and Saccharose (Molverhältnis 3:1, 190 °C, 30 min) isoliert and synthetisiert. Es handelt sich um 2,3-Bis-(1-Pyrrolidinyl)-2-cyclopenten-1-on und 2,3-Bis-(1-Pyrrolidinyl)-5-methyliden-2-cyclopenten-1-on. Die Erkennungsschwellenwerte (mmol/1) sind 0,15-0,25 and 0,06-0,12. Beide Verbindungen haben einen brennend-bitteren Geschmack. Aus einem Maltose-Prolin-Umsetzungsgemisch gelang die Isolierung des 2--Glucosyl-5-hydroxy-5-methyl-4-piperidinyl-2-cyclopenten-1-ons. Bei der Reaktion des Dihydropyranons VI mit Prolin wurden u. a. das 2,5-Dihydroxy-5-methyl-4-prolinyl2-cyclopenten-1-on sowie die Cyclopent(b)azepinone XI and XII gebildet. Diese Verbindungen sind ebenfalls mehr oder weniger stark bitter. 相似文献
29.
Methods are described for solving a system of linear equations with error bounds. Rectangular and spherical intervals ofR n are used combined. The objective is to get guaranteed accuracy with a minimal effort of computing time. 相似文献