Reflexion von Clusterstrahlen an einem Echelettegitter / Reflection of Cluster Beams on an Echelette Grating

1973 ◽  
Vol 28 (10) ◽  
pp. 1733-1734
Author(s):  
H. Mayer
Keyword(s):  
Surface Structure ◽  
Flux Distribution ◽  
The Mean ◽  
Cluster Beams ◽  
Reflection Characteristics ◽  
Echelette Grating

Nitrogen cluster beams are reflected from an Echelette grating to investigate the influence of the surface structure on the reflection characteristics. If the mean cluster diameter is greater than the effective grating constant the same flux distribution is found as for a polished reflector. However, the flux distribution clearly spreads out in the plane of incidence if the cluster diameter becomes almost equal to the effective grating constant.

Sunshape and Its Influence on the Flux Distribution in Imaging Solar Concentrators

1992 ◽  
Vol 114 (4) ◽  
pp. 260-266 ◽  
Author(s):  
M. Schubnell
Keyword(s):  
Concentration Ratio ◽  
Flux Distribution ◽  
Measurement Techniques ◽  
Solar Limb ◽  
Solar Furnace ◽  
Optical Systems ◽  
Solar Concentrators ◽  
Parabolic Dish ◽  
The Mean ◽  
Mean Concentration

Imaging solar concentrators, such as a parabolic dish, image the sun to their focal plane. Thus, the flux distribution is basically an image of the angular distribution of the direct incident solar radiation. This distribution, referred to as sunshape, is determined by solar limb darkening and by small angle scattering in the atmosphere. In this paper we present measurements of the sunshape and investigate its influence on the flux distribution in the solar furnace at Paul Scherrer Institute (PSI) and in parabolic concentrators, both experimentally and by a ray tracing procedure. Analyzing the influence of the spectral dependence of the sunshape we find that the characteristic width of the focal spot increases with longer wavelengths. In contrary, the mean concentration ratio is higher at shorter wavelengths. Although these effects are rather small, they can be important in radiometric measurement techniques to determine the emissivity and the temperature distribution of an irradiated sample as well as in designing solar pumped lasers. Comparing various sunshapes with the corresponding flux distributions in the two-stage solar furnace at PSI, we show that the influence of the circumsolar radiation on the flux distribution is usually negligible as compared to the distortion due to astigmatism. However, in more accurate optical systems, such as highly concentrating parabolic dishes, the flux distribution is a fairly accurate image of the sunshape. We find, that due to sunshape, the mean concentration ratio in a parabolic dish is decreased by about ten percent. As an example we subsequently estimate the mean annual conversion efficiency of an ideal solar converter operated in the Swiss mountains.

Kinetics Of The Growth Of Copper Clusters On The Alumina (0001) Surface : Influence Of Surface Structure

1998 ◽  
Vol 524 ◽  
Author(s):  
M. Gautier-Soyek ◽  
S. Gota ◽  
L. Douillard ◽  
P. Le Fevre ◽  
H. Magnan ◽  
...  
Keyword(s):  
Surface Structure ◽  
Room Temperature ◽  
Deposition Time ◽  
Cluster Radius ◽  
Copper Clusters ◽  
The Mean ◽  
Reconstructed Surface ◽  
Kinetics Of ◽  
Diffusion Properties

ABSTRACTThe kinetics of the growth of copper clusters on the alumina (0001) surface was studied as a function of surface structure, using EXAFS at the Cu K edge. Equivalent Cu coverages ranging from 0.5 to 4 equivalent monolayers were deposited in situ, at room temperature, on alumina (0001) surfaces exhibiting the (1×1) or the reconstructed structure. The evolution of mean cluster size with deposition time was followed from the mean Cu coordination number in the clusters deduced from the EXAFS data. The increase of the mean cluster radius with deposition time is characteristic of a coalescence mechanism on both surfaces. The growth is quicker on the reconstructed surface, likely due to different surface diffusion properties of both surfaces.

scholarly journals Continuous statistics of the Ly  forest at 0

2007 ◽  
Vol 376 (3) ◽  
pp. 1227-1237 ◽  
Author(s):  
D. Kirkman ◽  
D. Tytler ◽  
D. Lubin ◽  
J. Charlton
Keyword(s):  
Flux Distribution ◽  
The Mean

Tessellation of SoHO Magnetograms

2000 ◽  
Vol 179 ◽  
pp. 265-268
Author(s):  
R. Srikant ◽  
Jagdev Singh
Keyword(s):  
Magnetic Flux ◽  
Large Scale ◽  
Flux Distribution ◽  
Opposite Polarity ◽  
Size Distributions ◽  
Heliospheric Observatory ◽  
Surface Filling ◽  
Gradient Based ◽  
The Mean ◽  
Exponential Fit

AbstractA gradient based algorithm which divides arbitrary images into non-overlapping surface filling tiles of opposite polarity is used to study the flux and size distributions of large scale magnetic flux concentrations in solar and heliospheric observatory (SoHO) magnetograms. The mean absolute flux and size of the concentrations at the considered scale is found to be about 1.7 × 1018Mx and 5.2 Mm for both polarities. The form of the flux distribution is characterized by a skewness ofα3= 4.9 and a kurtosis ofα4= 42.8. The fall in the distribution in the range 6.5 × 1017Mx to 5 × 1018Mx is described by an exponential fit, in agreement with a model for the sustenance of quiet region flux.

Advance in the diagnosis of esophageal carcinoma

1998 ◽  
Vol 39 (1) ◽  
pp. 47-51 ◽  
Author(s):  
T. Ueyama ◽  
K. Kawamoto ◽  
Y. Yamada ◽  
H. Yoshikawa ◽  
K. Masuda
Keyword(s):  
Image Quality ◽  
Esophageal Carcinoma ◽  
Surface Structure ◽  
Clinical Utility ◽  
Double Contrast ◽  
Radiographic Images ◽  
Optimal Values ◽  
The Mean ◽  
Esophageal Carcinomas

Purpose: to assess the clinical utility of computed radiographic images processed with adaptive spatial filtering (ASF) in the diagnosis of esophageal carcinoma Material and Methods: After determining the optimal values for ASF image parameters in double-contrast barium studies, we used ASF to process the esophagograms of 35 patients with 37 esophageal carcinomas (superficial 20, advanced 17). the image quality of each lesion was evaluated independently by four radiologists on the basis of detectability, extent, and surface structure. the scoring was: 1 when the ASF image was superior to the original; — 1 when the converse was true; and 0 when quality of images was equal Results: in superficial carcinoma, the mean scores for image quality with regard to detectability, extent, and surface structure were 0.19, 0.48, and 0.31 respectively. in advanced carcinoma, the scores were 0.00, 0.76, and 0.25 respectively Conclusion: ASF offers an improved image quality which is valuable in the evaluation of esophageal carcinoma, particularly in the detection of superficial carcinomas and in the identification of intraepithelial extension

scholarly journals Mapping Structure and Morphology of Soler Glacier, in Northern Patagonia, Chile, Using Near-Vertical, Aerial Photographs, Taken with a Non-Metric, 6 X 6 CM-Format Camera

1986 ◽  
Vol 8 ◽  
pp. 8-10 ◽  
Author(s):  
Masuma Aniya ◽  
Renji Naruse
Keyword(s):  
Surface Structure ◽  
Flow Rate ◽  
Surface Flow ◽  
Aerial Photographs ◽  
Middle Reach ◽  
Outlet Glacier ◽  
Structure And Morphology ◽  
Northern Patagonia ◽  
Eastern Side ◽  
The Mean

The surface structure and morphpology of the Soler Glacier, an outlet glacier located on the eastern side of the Patagonia Northern Icefield, were mapped and analysed, using near-vertical, aerial photographs, taken with a hand-held, 6x6 cm-format camera, in January, 1984. The major findings, which could hardly be obtained in the field, included identification of the five ice bodies and four sets of ogive patterns. The pattern and distribution of crevasses were also analysed. From the number and spacings of the ogives, the mean, annual, surface-flow rate was deduced to be about 100 m and 350 m, at points 1.4 km and 6.6 km from the snout, respectively, with an average of 160 m for the middle reach.

SIMULATION OF ION FLUX DISTRIBUTION IN CONDUCTIVE AND NONCONDUCTIVE NANOTIP PATTERNS

2006 ◽  
Vol 05 (04n05) ◽  
pp. 621-626
Author(s):  
I. LEVCHENKO ◽  
K. OSTRIKOV
Keyword(s):  
Monte Carlo ◽  
Current Distribution ◽  
Current Density ◽  
Flux Distribution ◽  
Ion Current ◽  
Substrate Bias ◽  
Nanoparticle Arrays ◽  
The Mean ◽  
Simulation Results ◽  
Negative Substrate Bias

The distribution of flux of carbon-bearing cations over nanopatterned surfaces with conductive nanotips and nonconductive nanoislands is simulated using the Monte-Carlo technique. It is shown that the ion current is focused to nanotip surfaces when the negative substrate bias is low and only slightly perturbed at higher substrate biases. In the low-bias case, the mean horizontal ion displacement caused by the nanotip electric field exceeds 10 nm. However, at higher substrate biases, this value reduces down to 2 nm. In the nonconductive nanopattern case, the ion current distribution is highly nonuniform, with distinctive zones of depleted current density around the nanoislands. The simulation results suggest the efficient means to control ion fluxes in plasma-aided nanofabrication of ordered nanopatterns, such as nanotip microemitter structures and quantum dot or nanoparticle arrays.

scholarly journals Mapping Structure and Morphology of Soler Glacier, in Northern Patagonia, Chile, Using Near-Vertical, Aerial Photographs, Taken with a Non-Metric, 6 X 6 CM-Format Camera

1986 ◽  
Vol 8 ◽  
pp. 8-10
Author(s):  
Masuma Aniya ◽  
Renji Naruse
Keyword(s):  
Surface Structure ◽  
Flow Rate ◽  
Surface Flow ◽  
Aerial Photographs ◽  
Middle Reach ◽  
Outlet Glacier ◽  
Structure And Morphology ◽  
Northern Patagonia ◽  
Eastern Side ◽  
The Mean

The surface structure and morphpology of the Soler Glacier, an outlet glacier located on the eastern side of the Patagonia Northern Icefield, were mapped and analysed, using near-vertical, aerial photographs, taken with a hand-held, 6x6 cm-format camera, in January, 1984. The major findings, which could hardly be obtained in the field, included identification of the five ice bodies and four sets of ogive patterns. The pattern and distribution of crevasses were also analysed. From the number and spacings of the ogives, the mean, annual, surface-flow rate was deduced to be about 100 m and 350 m, at points 1.4 km and 6.6 km from the snout, respectively, with an average of 160 m for the middle reach.

Photo-electric Hβ and uvby photometry

1966 ◽  
Vol 24 ◽  
pp. 170-180
Author(s):  
D. L. Crawford
Keyword(s):  
Narrow Band ◽  
Line Strength ◽  
Interference Filter ◽  
B Stars ◽  
Relative Line ◽  
The Mean ◽  
F Stars ◽  
Two Parameters ◽  
Filter Photometry ◽  
The Continuum

Early in the 1950's Strömgren (1, 2, 3, 4, 5) introduced medium to narrow-band interference filter photometry at the McDonald Observatory. He used six interference filters to obtain two parameters of astrophysical interest. These parameters he calledlandc, for line and continuum hydrogen absorption. The first measured empirically the absorption line strength of Hβby means of a filter of half width 35Å centered on Hβand compared to the mean of two filters situated in the continuum near Hβ. The second index measured empirically the Balmer discontinuity by means of a filter situated below the Balmer discontinuity and two above it. He showed that these two indices could accurately predict the spectral type and luminosity of both B stars and A and F stars. He later derived (6) an indexmfrom the same filters. This index was a measure of the relative line blanketing near 4100Å compared to two filters above 4500Å. These three indices confirmed earlier work by many people, including Lindblad and Becker. References to this earlier work and to the systems discussed today can be found in Strömgren's article inBasic Astronomical Data(7).

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

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