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61.
A. V. Räisänen W. R. McGrath D. G. Crete P. L. Richards 《Journal of Infrared, Millimeter and Terahertz Waves》1985,6(12):1169-1189
Several scaled models have been used to determine the contributions of various waveguide mount parameters to the embedding impedance of a mm-wave SIS mixer. Measured effects of waveguide height, substrate orientation and width, junction location, lead inductance and RF-filter impedance are presented and discussed. 相似文献
62.
Summary ESCA is used to characterize ion beam irradiated P(p-ClPhMA)-samples. The results show a chlorine abstraction. The experimental
findings are in accordance with a recently proposed model for a crosslinking mechanism of halogenated aromatic polymers. 相似文献
63.
64.
Prof. Dr.-Ing. M. Michel Dr.-Ing. Th. Schütze 《Electrical Engineering (Archiv fur Elektrotechnik)》1991,74(6):419-426
Übersicht Mit Hinblick auf die zunehmend Verbreitung findende Pulsmusterberechnung in Echtzeit werden in dem Aufsatz Gesichtspunkte diskutiert, die sich aus den Eigenschaften des leistungselektronischen Stellgliedes, des Pulswechselrichters, ergeben. Die bei Abtastregelungen für die Dauer einer Abtastperiode konstante Stellgröße muß bei ihm durch Pulsweitenmodulation in ein Pulsmuster mit konstanter Amplitude und Pulsen variabler Breite umgesetzt werden. Durch ein neues Verfahren mit versetzter Abtastung haben dabei Rechentotzeiten bis zur Dauer einer halben Abtastperiode keinen Einfluß mehr auf das Pulsmuster.
Herrn Prof. Dr.-Ing. Klemens Heumann zum 60. Geburtstag gewidmet 相似文献
Algorithms for pulswidth modulation of inverters with online calculated pulse patterns
Contents Online calculation of pulse patterns will be employed more intensively in the future. Aspects concerning the powereleotronic circuit, the pulsewidth-modulated inverter, are to be discussed. The set value being constant for the duration of a sampling interval, has to be converted by a modulation algorithm into a pulse pattern with constant amplitude and pulses of variable width. Calculation dead-times up to half of sampling interval have no influence on the pulse pattern when using a new algorthm with shifted sampling instants.
Herrn Prof. Dr.-Ing. Klemens Heumann zum 60. Geburtstag gewidmet 相似文献
65.
66.
Daniel Röhnert Fritz Phillipp Helfried Reuther Till Weber Egbert Wessel Michael Schütze 《Oxidation of Metals》2007,68(5-6):271-293
The initial stages of the metal-dusting process on Alloy 800 at 620 °C were investigated by light optical microscopy, RAMAN
spectroscopy, atomic-force microscopy, Auger electron spectroscopy, transmission-electron microscopy and electron back-scatter
diffraction. As it turned out the incubation period for metal-dusting is characterized by simultaneous formation of a heterogeneously
growing oxide scale and deposition of carbon. The material surface shows different tarnish colors depending on the substrate-grain
orientation with different susceptibility to the beginning of metal-dusting attack. “Low-index” grains were not attacked within
the times investigated while the other grain orientations showed pitting. Carbon is evidently incorporated into the oxide
scale from the very beginning of exposure with different intensities depending on the underlying substrate-grain orientation
leading to differences in the tarnish colors. As a consequence carbides are formed even underneath “dense” oxide layers. Evidently
metal-dusting attack starts at positions of the oxide scale where “higher carbon concentrations” are present. 相似文献
67.
The next generation of video tapes will use evaporated thin films with their superior properties such as recording density, output level, frequency characteristics and signal-to-noise ratio. This paper describes the metal layer formation by a simple model for the growth of microcolumns at oblique incidence deposition. The most relevant process parameters are discussed. The layout of a production coater is described. 相似文献
68.
W Matthiessen N Sch?nfeld H Mauch U Wahn A Grassot 《Canadian Metallurgical Quarterly》1993,118(5):139-144
The chest radiograph of a 35-year-old man with fatigue, exertional dyspnoea and haemoptyses revealed a cavity in the left upper lobe and a shrunken left lung with radiolucency greater than that on the right. Acid-fast rods in sputum were identified as Mycobacterium kansasii on culture. Scintigraphy showed a 9% residual perfusion on the left and abnormal ventilation, compatible with Swyer-James syndrome. This had favoured the development of a mycobacterial infection. There was also a decrease in ciliary function (rate of 4-7 Hz, normal: 10-11). Treatment, begun when tuberculosis had been suspected, was after sensitivity tests changed to a combination of rifampicin (600 mg), ethambutol (1600 mg) and protionamide (500 mg) daily. There was marked regression of the findings within 4 weeks, but treatment was prematurely stopped after 11 months. Two years later there was a recurrence which again responded well to the same drug regimen with additional sulphamethoxazole (1600 mg/d). 相似文献
69.
D. Y. C. Lie A. Vantomme F. Eisen T. Vreeland M. -A. Nicolet T. K. Carns K. L. Wang B. Holländer 《Journal of Electronic Materials》1994,23(4):369-373
We compare both the strain and damage that 100 keV Si irradiation at room temperature introduces in pseudomorphic and relaxed
GexSi1−x films grown on Si(100) substrates. The ion range is such that the Si/GexSi1−x interface is not significantly damaged. The amount of damage produced in pseudomorphic and relaxed GexSi1−x layers of similar x for irradiation doses up to 2.5 × 1014 Si/cm2 is the same, which proves that a pre-existing uniform strain does not noticeably affect the irradiation-induced damage. However,
the irradiation-induced strain does depend on the pre-existing strain of the samples. Possible interpretations are discussed.
On leave from Inst. voor Kern en Stralingsfysika, Catholic University of Leuven, Belgium. 相似文献
70.
If the previous restorative therapy or dental caries has resulted in substantial loss of tooth structure, the abutment teeth for fixed prosthodontic restorations require a core reconstruction or a post and core. Small dentin defects can be restored with bonded cores; more extensive dentin defects that are often accompanied by previous endodontic treatment generally require additional support for the core material. A direct procedure with a bonded post is a viable treatment method. The decision to use either light-conducting all-ceramic zirconium or titanium as a post material depends on the aesthetic requirements present. The indications for a cast post and core as an indirect procedure for prosthodontic reconstructions appear to be decreasing. The learning objective of this article is to review the past and current post and core materials and techniques. Indications for core reconstruction with vital teeth and posts and cores for pulpless teeth are discussed. 相似文献