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排序方式: 共有213条查询结果,搜索用时 31 毫秒
21.
Thomas H. Büttgenbach Todd D. Groesbeck Brain N. Ellison 《International Journal of Infrared and Millimeter Waves》1990,11(1):1-20
We report results from measurements of a scale mixer model, built to investigate the embedding impedance presented to a superconductor-insulator-superconductor (SIS) tunnel junction detector in a full height waveguide with two tuning elements. The embedding impedance is measured as a function of junction position across the waveguide channel. The results are compared to i) computer simulations of the embedding impedance using waveguide theory, ii) a lumped element circuit derived from the theory, iii) an SIS receiver operating between 200 and 280 GHz. 相似文献
22.
Desimoni and Brunetti raise some questions about the use of Eurachem/CITAC guide, because the Eurachem/CITAC guide does not
discuss an ISO recommendation before performing a test, it should be decided whether it is to be a test for conformity or
a test for non-conformity. In response, it is pointed out that although this recommendation is not discussed explicitly, it
is of necessity covered by the decision rule that describes how the measurement uncertainty will be taken into consideration
with regard to accepting or rejecting a product according to its specification and the result of a measurement. In addition,
they propose the introduction of an ‘inconclusive’ zone. We do not think that this is necessary, since the Eurachem/CITAC
guide takes the view that action on rejection should be covered by the ‘decision rule’ and this can make equivalent provision
for confirmation or interpretation. 相似文献
23.
Standard uncertainties obtained by the GUM approach for a range of analytical methods are compared directly and indirectly
with estimates of reproducibility standard deviation for the same methods. Results were obtained from both routine analysis
and international key comparisons. A general tendency for the uncertainty to be substantially less than the reproducibility
standard deviation was found. 相似文献
24.
Dawud H. Tan Chunfeng Zhou Christopher J. Ellison Satish Kumar Christopher W. Macosko Frank S. Bates 《ournal of non Newtonian Fluid Mechanics》2010,165(15-16):892-900
Both melt viscosity (ηo) and elasticity (correlated here with the longest melt relaxation time λ1) were found to control the diameter distribution of meltblown fibers. Fibers were formed by melt blowing binary polystyrene (PS) blends containing widely differing component molecular weights using a custom-built laboratory apparatus. Varying the concentration and molecular weight of a high molecular weight PS provided independent control over ηo and λ1. These rheological parameters influence the average diameter (dav) and the distribution of diameters (coefficient of variation, CV) of meltblown fibers in different ways. Increasing ηo leads to an increase in dav but has little impact on CV. On the other hand, increasing λ1 beyond a threshold value reduces CV while simultaneously increasing dav. A one-dimensional slender-jet theoretical model with both upper convected Maxwell and Phan–Thien and Tanner constitutive equations was developed to investigate the influence of viscoelasticity and processing parameters on the properties of meltblown fibers. This model predicts a strong dependence of fiber diameter on the air shear stress and variations in fiber diameter with viscoelasticity that are in qualitative agreement with the experimental results. We believe these results suggest that carefully controlling the viscoelastic profile of polymers used in melt blowing is a viable approach for producing nanofibers with narrow fiber diameter distributions using current commercial equipment. 相似文献
25.
Ben Ellison Jonathan Fleischmann Dan McGinn Wim Ruitenburg 《Mathematical Logic Quarterly》2007,53(3):311-320
We define two notions for intuitionistic predicate logic: that of a submodel of a Kripke model, and that of a universal sentence. We then prove a corresponding preservation theorem. If a Kripke model is viewed as a functor from a small category to the category of all classical models with (homo)morphisms between them, then we define a submodel of a Kripke model to be a restriction of the original Kripke model to a subcategory of its domain, where every node in the subcategory is mapped to a classical submodel of the corresponding classical model in the range of the original Kripke model. We call a sentence universal if it is built inductively from atoms (including ? and ⊥) using ∧, ∨, ?, and →, with the restriction that antecedents of → must be atomic. We prove that an intuitionistic theory is axiomatized by universal sentences if and only if it is preserved under Kripke submodels. We also prove the following analogue of a classical model‐consistency theorem: The universal fragment of a theory Γ is contained in the universal fragment of a theory Δ if and only if every rooted Kripke model of Δ is strongly equivalent to a submodel of a rooted Kripke model of Γ. Our notions of Kripke submodel and universal sentence are natural in the sense that in the presence of the rule of excluded middle, they collapse to the classical notions of submodel and universal sentence. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
26.
Barwick Vicki Ellison Stephen L. R. Gjengedal Elin Magnusson Bertil Molinier Olivier Patriarca Marina Sibbesen Lorens Vanlaethem Nicole Vercruysse Isabelle 《Accreditation and quality assurance》2017,22(5):253-263
Accreditation and Quality Assurance - Eurachem held a workshop on method validation in analytical sciences in Gent, Belgium, on 9–10 May 2016. A summary of the working group discussions is... 相似文献
27.
Bates CM Strahan JR Santos LJ Mueller BK Bamgbade BO Lee JA Katzenstein JM Ellison CJ Willson CG 《Langmuir : the ACS journal of surfaces and colloids》2011,27(5):2000-2006
The orientation of cylinder-forming poly(styrene-block-methyl methacrylate) [P(S-b-MMA)] was investigated on two sets of polymeric surface treatments: 10 para-substituted polystyrene derivatives with <10 mol % poly(4-vinylbenzyl azide) and a series of poly(styrene-random-4-vinylbenzyl azide) [P(S-r-VBzAz)] copolymers with 5-100 mol % poly(4-vinylbenzyl azide). The copolymers were spin-coated to form thin films and then cross-linked by heating. The resulting films exhibited a range of surface tensions from 21 to 45 dyn/cm. Perpendicular orientation of P(S-b-MMA) cylinders was achieved with poly(p-bromostyrene) and all the [P(S-r-VBzAz)] copolymer surface treatments, most notably the homopolymer of poly(4-vinylbenzyl azide). Films made from these simple copolymers are as effective as random terpolymer alignment layers commonly made from both block monomers and a cross-linkable monomer. 相似文献
28.
Osteryoung square-wave voltammetric analysis is a rapid technique that can be used to determine nicarbazin residues in chicken tissue. The method is reproducible and can be applied to samples containing as little as 1-10 mug/g nicarbazin. This level of sensitivity is more than adequate for meeting governmental regulations. Osteryoung square-wave voltammetry is significantly faster than classical differential pulse polarography. 相似文献
29.
Photodetachment cross sections of trapped electrons are expressed analytically by a one-parameter model with an initial 1s bound state and a final plane-wave state. The theoretical cross-section curve, location of the peak maximum, and band width are discussed. Calculated photoabsorption profiles compare fairly well with experimental data. Comment is made concerning the ω?8/3 photon-energy dependence for the bound-continuum band shape previously proposed in resolution of the absorption spectrum of trapped electrons into bound-bound and bound-continuum bands. 相似文献
30.
Z. B. Marii L. P. Ellison B. G. Gowland G. A. Gledhill 《International Journal of Infrared and Millimeter Waves》1994,15(1):247-261
The mini-computer and control electronics of a Bruker 113v Fourier Transform Spectrometer (FTS), capable of 0.03 cm–1 resolution for frequencies up to 4000cm–1, have been replaced by an inexpensive IBM-PC 486-based system. The original performance is exceeded. JCAMP-DX standard is used for data exchange. The system can be adapted to any FTS or similar instrument which requires time domain data acquisition. 相似文献