1,463 research outputs found
Thermal protection system and related methods
A thermal protection system and a method of manufacturing are disclosed. The thermal protection system may be configured to protect a movable joint, for example, a flexible bearing of a rocket motor nozzle. The thermal protection system includes a series of annular shims separated by a plurality of discrete spacers. Each shim of the series of annular shims may have a larger diameter than the previous shim, and the shims may nest. The shims may comprise a thermally stable material, and the discrete spacers may comprise an elastomer. Optionally, an annular bearing protector may separate the annular shims from the flexible bearing
Two Remarks on Graph Norms
For a graph H, its homomorphism density in graphs naturally extends to the space of two-variable symmetric functions W in Lp, pâ„e(H), denoted by t(H, W). One may then define corresponding functionals â„Wâ„H:=|t(H,W)|1/e(H) and â„Wâ„r(H):=t(H,|W|)1/e(H), and say that H is (semi-)norming if â„â
â„H is a (semi-)norm and that H is weakly norming if â„â
â„r(H) is a norm. We obtain two results that contribute to the theory of (weakly) norming graphs. Firstly, answering a question of Hatami, who estimated the modulus of convexity and smoothness of â„â
â„H, we prove that â„â
â„r(H) is neither uniformly convex nor uniformly smooth, provided that H is weakly norming. Secondly, we prove that every graph H without isolated vertices is (weakly) norming if and only if each component is an isomorphic copy of a (weakly) norming graph. This strong factorisation result allows us to assume connectivity of H when studying graph norms. In particular, we correct a negligence in the original statement of the aforementioned theorem by Hatami
Matching the termination of radiating non-uniform transmission-lines
In this contribution a concept of matching the termination of radiating non-uniform transmission-lines is proposed. Using Transmission-Line Super Theory, position and frequency dependent line parameters can be obtained. Therefore, a characteristic impedance can be determined which is also position and frequency dependent. For a single wire transmission-line it could be shown that the maximum value of that characteristic impedance is an optimal termination in the sense of minimizing the variation of the current on the line. This indicates that matching is not a local effect at the position of the concentrated load but a cooperative process including the whole non-uniform transmission-line. In addition this choice of termination minimizes the variation of the radiated power over frequency
A Unified Interface Model for Dissipative Transport of Bosons and Fermions
We study the directed transport of bosons along a one dimensional lattice in
a dissipative setting, where the hopping is only facilitated by coupling to a
Markovian reservoir. By combining numerical simulations with a field-theoretic
analysis, we investigate the current fluctuations for this process and
determine its asymptotic behavior. These findings demonstrate that dissipative
bosonic transport belongs to the KPZ universality class and therefore, in spite
of the drastic difference in the underlying particle statistics, it features
the same coarse grained behavior as the corresponding asymmetric simple
exclusion process (ASEP) for fermions. However, crucial differences between the
two processes emerge when focusing on the full counting statistics of current
fluctuations. By mapping both models to the physics of fluctuating interfaces,
we find that dissipative transport of bosons and fermions can be understood as
surface growth and erosion processes, respectively. Within this unified
description, both the similarities and discrepancies between the full counting
statistics of the transport are reconciled. Beyond purely theoretical interest,
these findings are relevant for experiments with cold atoms or long-lived
quasi-particles in nanophotonic lattices, where such transport scenarios can be
realized.Comment: comments welcom
Analyzing the footprints of near-surface aqueous turbulence: An image processing-based approach
In this contribution, a detailed investigation of surface thermal patterns on the water surface is presented, with wind speeds ranging from 1 to 7âmâs âââ1 and various surface conditions. Distinct structures can be observed on the surfaceâsmall-scale short-lived structures termed fish scales and larger-scale cold streaks that are consistent with the footprints of Langmuir circulations. The structure of the surface heat pattern depends strongly on wind-induced stress. Consistent behavior regarding the spacing of cold streaks can be observed in a range of laboratory facilities when expressed as a function of water-sided friction velocity, uâ*â. This behavior systematically decreased until a point of saturation at uâ*ââ=â0.7âcm/s. We present a new image processing-based approach to the analysis of the spacing of cold streaks based on a machine learning approach to classify the thermal footprints of near-surface turbulence. Comparison is made with studies of Langmuir circulation and the following key points are found. Results suggest a saturation in the tangential stress, anticipating that similar behavior will be observed in the open ocean. A relation to Langmuir numbers shows that thermal footprints in infrared images are consistent with Langmuir circulations and depend strongly on wind wave conditions
Microstructure and texture analysis of ÎŽ-hydride precipitation in Zircaloy-4 materials by electron microscopy and neutron diffraction
This work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated ÎŽ-ZrH1.66 generally follows the ÎŽ (111) //α (0001) and ÎŽ[]//α[] orientation relationship with the α-Zr matrix. The ÎŽ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and ÎŽ-hydride. Neutron diffraction line profile analysis and high-resolution transmission electron microscopy observations reveal a significant number of dislocations present in the ÎŽ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α-Zr matrix. The present observations provide an insight into the behaviour of ÎŽ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides.Fil: Wang, Zhiyang. University of Wollongong; Australia. Australian Nuclear Science and Technology Organisation; AustraliaFil: Garbe, Ulf. Australian Nuclear Science and Technology Organisation; AustraliaFil: Li, Huijun. University of Wollongong; AustraliaFil: Wang, Yanbo. University of Sydney; AustraliaFil: Studer, Andrew J.. Australian Nuclear Science and Technology Organisation; AustraliaFil: Sun, Guangai. Institute of Nuclear Physics and Chemistry, CAEP; ChinaFil: Harrison, Robert P.. Australian Nuclear Science and Technology Organisation, Institute of Materials Engineering; AustraliaFil: Liao, Xiaozhou. University of Sydney; AustraliaFil: Vicente Alvarez, Miguel Angel. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de EnergĂa Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Santisteban, Javier Roberto. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de EnergĂa Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Kong, Charlie. University of New South Wales; Australi
High-Resolution Imaging of Texture and Microstructure by the Moving Detector Method
In order to describe texture and microstructure of a polycrystalline material completely, crystal orientation g={?1F?2} must be known in all points x={x1?x2?x3} of the material. This can be achieved by locationresolved diffraction of high-energy, i.e. short-wave, X-rays from synchrotron sources. Highest resolution in the orientation- as well as the location-coordinates can be achieved by three variants of a detector sweeping technique in which an area detector is continuously moved during exposure. This technique results in two-dimensionally continuous images which are sections and projections of the six-dimensional orientation location space. Further evaluation of these images depends on whether individual grains are resolved in them or not. Because of the high penetration depth of high-energy synchrotron radiation in matter, this technique is also, and particularly, suitable for the investigation of the interior of big samples.researc
Quality assurance in immunoassay performance â carbamazepine immunoassay format evaluation and application on surface and waste water
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugĂ€nglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Carbamazepine (CBZ) is one of the most frequently detected pharmaceuticals in water samples. For the determination of this anthropogenic marker, various immunoassay formats were tested and evaluated in order to identify the most suitable one. For these direct competitive assays, the analyte was labelled with the enzyme horseradish peroxidase (HRP) or alkaline phosphatase (AP), and seven substrates with specific detection properties were used. The quality criteria for the standard curves were fulfilled by all HRP assays and the chemiluminescence AP format. Furthermore, intra- and inter-plate coefficients of variation as a measure of the achievable precision were determined for the samples. The application of the AP assays to surface water was unfeasible due to CBZ concentrations below the quantifiable concentration range. Surface as well as waste water samples could be analyzed with the HRP assays. Here, the HRP assay employing the chromogenic substrate 3,3âČ,5,5âČ-tetramethylbenzidine yielded the best results
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