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181.
An electronic gas-flow controller system called Advanced Flow Control (AFC), which controls not only carrier gas pressure at the column inlet but also the total gas flow including the split flow, was designed and evaluated. BASIC programming of repetitive analyses of standard mixtures under varied split ratios and pressure programs allowed automated optimization of those conditions for the desired column loading and resolution between adjacent peaks. 相似文献
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K. Zimmer R. Böhme A. Braun B. Rauschenbach F. Bigl 《Applied Physics A: Materials Science & Processing》2002,74(4):453-456
Phase grating projection using a Schwarzschild objective is presented in conjunction with a process that allows laser-induced
etching of transparent materials at the interface of liquids, in order to generate periodical surface relief structures with
sub-micron resolution in fused silica. The achieved sinusoidal gratings exhibit a period of 780 nm and a depth of up to 180 nm,
having a roughness lower than 5 nm r.m.s. The depth and roughness of the gratings are related to the applied laser fluence
and pulse number. In addition to the grating formation, an overall removal of material at higher laser fluences was found.
Received: 3 December 2001 / Accepted: 5 December 2001 / Published online: 11 February 2002 相似文献
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Einsatz von DMS- und Piezomeßtechnik zur direkten Schubspannungsermittlung in der Kapillarrheometrie
P. Braun 《Rheologica Acta》1990,29(3):243-251
Zusammenfassung Der Stand der Kapillarheometrie mit den Vor- und Nachteilen der einzelnen Systeme und Meßverfahren wird dargestellt. Ausgehend von diesem Stand werden zwei alternative Meßverfahren, nämlich Piezo-Einzelkraftund DMS-Meßverfahren, zur direkten Schubspannungsermittlung besprochen und eine nach diesem Prinzip konzipierte Versuchsdüse vorgestellt. Die mit dieser Düse erhaltenen Meßergebnisse zeigen im Vergleich zu konventionell, d. h. unter Anwendung des Bagley-Verfahrens, ermittelten Fließkurven im Falle der Einzelkraftmessung gute Übereinstimmung. Das Problem der Einlaufdruckkorrektur ist bei diesem Konzept von vornherein nicht vorhanden, und der ununterbrochene Fließkanal erlaubt, bei entsprechender Erweiterung auf zwei Kraftaufnehmer, einen unproblematischen Einsatz im On-line- oder sogar im In-line-Betrieb in der Polymerverarbeitung.Schlüsselwörter Rheometrie; Kapillarrheometrie; Schubspannungsermittlung; Piezokraftmessung; DMS-Anwendung; Kunststoffschmelzen; On-line-Rheometrie
The state-of-the-art of capillary rheometry, especially the advantages and disadvantages of different systems, is presented. Two measuring methods, a piezo single-force transducer, and a strain-gauge device combined in a testing die are compared. The strain gauges are fixed at the outside of a small capillary to detect the resulting wall shear stress between inner surface of the die and polymer flow by measuring the axial strain in the wall of the die. The single force method uses an elastic section of the die which uncouples the die from the supporting structure without changing the cross-section of the flow. The uncoupled part of the die is supported by a stiff, piezo-force transducer that detects the integral effect of wall shear stress. The resulting flow curves compare well with those using the Bagley method. With the novel die no entrance pressure-loss correction is needed. In principle, it also could be used as an on-line device for polymer processing.
Vortrag, gehalten auf der Jahrestagung der Deutschen Rheologischen Gesellschaft, TH Darmstadt, 19.–21. April 1989. 相似文献
188.
Igor Rodin Timur Baygildiev Andrey Stavrianidi Arcady Braun Igor Rybalchenko Oleg Shpigun 《Chromatographia》2015,78(7-8):585-591
189.
Roofs of buildings in the vicinity of airports can be damaged by trailing vortices of aircraft during take-off and landing. Preliminary experimental investigations have been conducted in a water towing tank in order to examine a discrepancy between damage probability assumptions and actual roof damage frequency. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
190.
Micro- and Nanoscale Deformation Measurement of Surface and Internal Planes via Digital Image Correlation 总被引:1,自引:0,他引:1
T. A. Berfield J. K. Patel R. G. Shimmin P. V. Braun J. Lambros N. R. Sottos 《Experimental Mechanics》2007,47(1):51-62
The digital image correlation (DIC) technique is successfully applied across multiple length scales through the generation
of a suitable speckle pattern at each size scale. For microscale measurements, a random speckle pattern of paint is created
with a fine point airbrush. Nanoscale displacement resolution is achieved with a speckle pattern formed by solution deposition
of fluorescent silica nanoparticles. When excited, the particles fluoresce and form a speckle pattern that can be imaged with
an optical microscope. Displacements are measured on the surface and on an interior plane of transparent polymer samples with
the different speckle patterns. Rigid body translation calibrations and uniaxial tension experiments establish a surface displacement
resolution of 1 μm over a 5×6 mm scale field of view for the airbrushed samples and 17 nm over a 100×100 μm scale field of
view for samples with the fluorescent nanoparticle speckle. To demonstrate the capabilities of the method, we characterize
the internal deformation fields generated around silica microspheres embedded in an elastomer under tensile loading. The DIC
technique enables measurement of complex deformation fields with nanoscale precision over relatively large areas, making it
of particular relevance to materials that possess multiple length scales. 相似文献