排序方式: 共有11条查询结果,搜索用时 15 毫秒
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B. Burghardt S. Büttgenbach N. Glaeser R. Harzer G. Meisel B. Roski F. Träber 《Zeitschrift für Physik A Hadrons and Nuclei》1982,307(3):193-200
The hyperfine structure constants and the electronic g J factor of the state 4f 11 6s 2 4 I 11/2 belonging to the holmium ground multiplet have been measured using the atomic beam magnetic resonance technique combined with a state-selective laser-induced detection of the resonant atoms. By the same method the g J factor of the level 4f 116s 24 I 9/2 was determined, while the hyperfine structures of this metastable state and of two high-lying even parity states have been investigated by high resolution laser spectroscopy. The results for the experimentalA andB factors of all four members of the ground multiplet allow a least-squares evaluation of the three magnetic dipole and the three electric quadrupole effective radial parameters for the configuration 4f 11 6s 2 of holmium, yielding an accurate value for the spectroscopic nuclear electric quadrupole moment:Q hfs(165Ho)=2.716(9)b (uncorrected for quadrupole shielding). From a comparison to the quadrupole moments measured in mesic holmium atoms the shielding factor could be estimated. 相似文献
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Andreas M. Glaeser 《Interface Science》2001,9(1-2):65-82
The energetic and kinetic properties of surfaces play a critical role in defining the microstructural changes that occur during sintering and high-temperature use of ceramics. Characterization of surface diffusion in ceramics is particularly difficult, and significant variations in reported values of surface diffusivities arise even in well-studied systems. Effects of impurities, surface energy anisotropy, and the onset of surface attachment limited kinetics (SALK) are believed to contribute to this variability. An overview of the use of Rayleigh instabilities as a means of characterizing surface diffusivities is presented. The development of models of morphological evolution that account for effects of surface energy anisotropy is reviewed, and the potential interplay between impurities and surface energy anisotropy is addressed. The status of experimental studies of Rayleigh instabilities in sapphire utilizing lithographically introduced pore channels of controlled geometry and crystallography is summarized. Results of model studies indicate that impurities can significantly influence both the spatial and temporal characteristics of Rayleigh instabilities; this is attributed at least in part to impurity effects on the surface energy anisotropy. Related model experiments indicate that the onset of SALK may also contribute significantly to apparent variations in surface diffusion coefficients. 相似文献
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Compliance with legal requirements: definition of limits, sampling and measurement uncertainty 总被引:1,自引:0,他引:1
Hermann Glaeser 《Accreditation and quality assurance》2002,7(10):388-391
In many cases compositional requirements for foodstuffs (e.g. limits for the fat, protein, dry matter, or water content) are
established by legislation. Adequate compliance testing is possible only if limits are clearly defined, taking measurement
and sampling uncertainty into consideration. Furthermore, decisions on compliance must be based on samples which reflect the
composition of the quantity to be evaluated. The resulting sample sizes are normally regarded by food inspection authorities
as being much larger than acceptable. Consequently, an alternative strategy should be developed. Autocontrol data (i.e. inspection
results obtained by the factory) in principle provide an adequate data basis for decisions on compliance. However, they must
be reliable and the food inspection authority must have access to these data on request. Using these data and on condition
that they show an approximate normal distribution, an inspection strategy based on arithmetic mean and standard deviation
can be developed. Reliable and transparent decisions on compliance can thus be made. In many cases an adequate verification
of food authenticity requires a comparison of raw material and product composition. Maximum acceptable differences, taking
the relevant sources of variation into consideration, have to be defined and should be used instead of limits.
Received: 17 April 2002 Accepted: 23 June 2002 相似文献
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Hermann Glaeser 《Accreditation and quality assurance》2004,9(4-5):205-208
Foodstuffs shall not contain pathogenic micro-organisms in concentrations which may cause a risk for consumer health. The relevant legislation therefore normally contains the requirement that these organisms are absent in a certain product quantity (e.g. 25 g). It is not at all easy to prove the absence. Reference materials are important tools for checking the performance of qualitative methods. These materials should contain the target organism in low numbers (close to 1 cell/capsule). Furthermore, the most important interfering micro-organisms should be taken into consideration, when testing the performance of detection methods using reference materials. When developing reference materials with the described characteristics, detection methods are needed which give a positive result with one or a few cell(s) of the target organism. While these requirements appear to be fairly obvious, precise statements on method performance are rarely available. Strategies to obtain this information are discussed. Further important aspects are practical considerations when using such reference materials for method evaluation. Statistical procedures can help to obtain the relevant information with a minimum of effort.Presented at BERM-9—Ninth International Symposium on Biological and Environmental Reference Materials, June 15–19, 2003, Berlin, Germany. Views expressed in this paper represent the personal opinion of the author. 相似文献
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Grain Boundary Migration in Ceramics 总被引:2,自引:0,他引:2
During ceramic fabrication, densification processes compete with coarsening processes to determine the path of microstructural evolution. Grain growth is a key coarsening process. This paper examines grain boundary migration in ceramics, and discusses the effects of solutes, pores, and liquid phases on grain boundary migration rates. An effort is made to highlight work in the past decade that has contributed to and advanced our understanding of solute drag effects, pore-boundary interactions, and the role of liquid phases in grain growth and microstructural evolution. Anisotropy of the grain boundary mobility, and its role in the development of anisotropic (anisometric) microstructures is discussed as it is a central issue in recent efforts to produce ceramic materials with new combinations of properties and functionality. 相似文献
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Xu Q Sharp ID Yuan CW Yi DO Liao CY Glaeser AM Minor AM Beeman JW Ridgway MC Kluth P Ager JW Chrzan DC Haller EE 《Physical review letters》2006,97(15):155701
The melting behavior of Ge nanocrystals embedded within SiO2 is evaluated using in situ transmission electron microscopy. The observed melting-point hysteresis is large (+/-17%) and nearly symmetric about the bulk melting point. This hysteresis is modeled successfully using classical nucleation theory without the need to invoke epitaxy. 相似文献
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利用简单的电阻器限制LED串中的电流看似最为经济和简便,那么为何还要费尽心思地使用线性驱动器IC? 相似文献
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Joachim Glaeser Hakan Yilmazer 《世界电子元器件》2007,(12):69-70
利用简单的电阻器限制LED串中的电流看似最为经济和简便,那么为何还要费尽心思地使用线性驱动器IC? 相似文献
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S. Büttgenbach N. Glaeser B. Roski F. Träber 《Zeitschrift für Physik A Hadrons and Nuclei》1984,317(3):237-240
The magnetic dipole hyperfine interaction constantsA of the atomic ground state3 D 3 and of the first excited state3 D 3 in195Pt have been measured by atomic beam magnetic resonance. The electronicg J factors of these states were determined from the Zeeman splitting in194Pt. Using intermediate coupling wave functions derived for the configurations (5d+6s)10 effective hyperfine radial integrals are evaluated. 相似文献