排序方式: 共有52条查询结果,搜索用时 187 毫秒
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Ilya Kuselman Elena Kardash Emil Bashkansky Francesca Pennecchi Stephen L. R. Ellison Karen Ginsbury Malka Epstein Aleš Fajgelj Yury Karpov 《Accreditation and quality assurance》2013,18(6):459-467
A new technique for quantification of human errors in chemical analysis using expert judgments is described. This technique is based on the house-of-security approach developed recently in the field of safety and security for prevention of terrorist and criminal attacks against an organization. The following relative quantification parameters (expressed in %) are proposed in the technique: (a) likelihood score of human error in a chemical analytical measurement/testing method, (b) severity score of human error for reliability of the test results, (c) importance score of a component of a laboratory quality system, and (d) effectiveness score of the quality system as a whole in preventing/blocking human error. As an example, 34 scenarios of human error in pH measurement of groundwater are discussed and quantified. 相似文献
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We have measured the coherent optical transition radiation emitted by an electron beam from laser-plasma interaction. The measurement of the spectrum of the radiation reveals fine structures of the electron beam in the range 400-1000 nm. These structures are reproduced using an electron distribution from a 3D particle-in-cell simulation and are attributed to microbunching of the electron bunch due to its interaction with the laser field. When the radiator is placed closer to the interaction point, spectral oscillations have also been recorded, signature of the interference of the radiation produced by two electron bunches delayed by 74 fs. The second electron bunch duration is shown to be ultrashort to match the intensity level of the radiation. Whereas transition radiation was used at longer wavelengths in order to estimate the electron bunch length, this study focuses on the ultrashort structures of the electron beam. 相似文献
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Walton B Najmudin Z Wei MS Marle C Kingham RJ Krushelnick K Dangor AE Clarke RJ Poulter MJ Hernandez-Gomez C Hawkes S Neely D Collier JL Danson CN Fritzler S Malka V 《Optics letters》2002,27(24):2203-2205
A short-pulse laser beat wave scheme for advanced particle accelerator applications is examined. A short, intense (3-ps, >10(18)-W cm(-2)) two-frequency laser pulse is produced by use of a modified chirped-pulse amplification scheme and is shown to produce relativistic plasma waves during interactions with low-density plasmas. The generation of plasma waves was observed by measurement of forward Raman scattering. Resonance was found to occur at an electron density many times that expected, owing to ponderomotive displacement of plasma within the focal region. 相似文献
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Glinec Y Faure J Dain LL Darbon S Hosokai T Santos JJ Lefebvre E Rousseau JP Burgy F Mercier B Malka V 《Physical review letters》2005,94(2):025003
An electron beam from a laser-plasma accelerator is converted into a gamma-ray source using bremsstrahlung radiation in a dense material. The gamma-ray beam has a pointlike source size because it is generated by a high quality electron beam with a small source size and a low divergence. Using this gamma-ray source, the radiography of complex and dense objects with submillimeter resolution is performed. It is the first evidence of a gamma-ray source size of a few hundreds micrometers produced with laser-driven accelerators. This size is consistent with results from Monte Carlo simulations. 相似文献
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Bouquet S Stéhlé C Koenig M Chièze JP Benuzzi-Mounaix A Batani D Leygnac S Fleury X Merdji H Michaut C Thais F Grandjouan N Hall T Henry E Malka V Lafon JP 《Physical review letters》2004,92(22):225001
We present a supercritical radiative shock experiment performed with the LULI nanosecond laser facility. Using targets filled with xenon gas at low pressure, the propagation of a strong shock with a radiative precursor is evidenced. The main measured shock quantities (electronic density and propagation velocity) are shown to be in good agreement with theory and numerical simulations. 相似文献
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Iwona E. Malka Tomasz Czujko Jerzy Bystrzycki Leszek R. Jaroszewicz 《Central European Journal of Chemistry》2011,9(4):701-705
The hydrogenation properties of magnesium hydride mechanically milled with iron fluorides (FeF2 and FeF3), were investigated by Temperature Programmed Desorption (TPD) and volumetric methods using a Sieverts-type apparatus, as
prepared upon dehydrogenation and finally upon subsequent hydrogenation. The activation energy of hydrogen desorption (Ea), calculated from the Kissinger formula using TPD measurements obtained with different heating rates, showed significant
decreases of Ea in comparison to that of milled MgH2 without any dopants. Moreover, the influence of these metal fluorides on the thermodynamics of the decomposition process
was also examined. In the case of the FeF2 dopant, rehydrogenation following desorption caused the complete decomposition of the iron fluoride to BCC iron and the formation
of a predominant MgH2 phase. In contrast to FeF2, the addition of FeF3 led to the formation of β-MgH2 as a major phase coexisting with Mg2FeH6 and MgF2 compounds. The presence of pure Fe in the MgH2+FeF2 composite, as opposed to MgH2+FeF3 containing Mg2FeH6 and MgF2, did not cause any significant influence on the sorption properties of MgH2. Moreover, the original material doped with FeF3 predominantly showed iron in the Mg2FeH6 compound, while the FeF2 dopant iron mostly showed the nearly pure BCC metallic phase
相似文献
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Y. A. Gauduel Y. Glinec J.-P. Rousseau F. Burgy V. Malka 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(1):121-135
The damages triggered by ionizing radiation on chemical and biological targets depend on the survival probability of radicals
produced in clusters of ionization-excitation events. In this paper, we report on femtolysis (FEMTOsecond radioLYSIS) of pure
liquid water using an innovative laser produced high-energy, ultra-short electron bunches in the 2.5-15 MeV range and high
energy radiation femtochemistry (HERF) measurements. The short-time monitoring of a primary reducing radical, hydrated electron
e-aq^{-}_{aq}, has been performed in confined ionization spaces (nascent spurs). The calculated yield of hydrated electrons at early time,
G(e-aq)ETG({\rm e}^{-}_{aq})_{ET}, is estimated to be 6.5 ± 0.5 (number/100 eV) at t ~ 5 ps after the ultrafast energy deposition. This estimated value is high compare to (i) the available data of previous
works that used scavenging techniques; (ii) the predictions of stochastic water radiolysis modelling for which the initial
behaviour of hydrated electron is investigated in the framework of a classical diffusion regime of independent pairs. The
HERF developments give new insights into the early ubiquitous radical escape probability in nascent aqueous spurs and emphasize
the importance of short-lived solvent bridged electron-radical complexes
[H3O+...{\rm H}_{3}{\rm O}^{+...}
eaq-{\rm e}_{aq}^{-} ..OH]nH2O{\rm OH}]_{n{\rm H}_2{\rm O}}
(non-independent pairs). A complete understanding of the
G(e-aq)ET{\rm e}^{-}_{aq})_{ET} value needs to account for quantum aspects of 1s-like trapped electron ground state and neoformed
prototropic radicals that govern ultra-fast recombination processes within these non-independent pair configurations. Femtolysis
data
emphasize that within a time-dependent non-diffusion regime, spatio-temporal correlations between hydrated electron and nearest
neighbours OH radical or hydrated proton (H3O+{\rm H}_{3}{\rm O}^{+}) would assist ultrafast anisotropic 1D recombination within solvent bridged electron-radical complexes. The emerging HERF
domain would provide guidance for understanding of ultrashort-lived sub-structure of tracks and stimulate future semi-quantum
simulations on prethermal radical reactions. 相似文献
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In this paper we present a super-resolved Raman spectroscopy configuration where, due to the proposed resolution improvement, more chemical species can be simultaneously detected. The idea includes usage of the basic property of Raman in which shifting the excitation wavelength will shift the absolute wavelength of the Raman spectral lines. Thus, encoding the spectra prior to analysis by the spectrometer allows obtaining spectral super-resolved sensing via time multiplexing super-resolution concepts applied over the spectral domain. 相似文献