Determination of Condition for Fastest Negative Group Velocities of Lamb‐Type Waves under each Density Ratio of Solid and Liquid Layers

2008 ◽  
Vol 123 (5) ◽  
pp. 3516-3516 ◽  
Author(s):  
Kojiro Nishimiya ◽  
Koichi Mizutani ◽  
Naoto Wakatsuki ◽  
Ken Yamamoto
Keyword(s):  
Density Ratio ◽  
Negative Group ◽  
Group Velocities

Impossibility of negative group velocities in a periodic layer structure with or without loss

2005 ◽  
Vol 250 (4-6) ◽  
pp. 258-265 ◽  
Author(s):  
Louis Poirier ◽  
Robert I. Thompson ◽  
Alain Haché
Keyword(s):  
Layer Structure ◽  
Negative Group ◽  
Periodic Layer ◽  
Group Velocities

Film Cooling of the Gas Turbine Endwall by Discrete-Hole Injection

1996 ◽  
Vol 118 (2) ◽  
pp. 278-284 ◽  
Author(s):  
M. Y. Jabbari ◽  
K. C. Marston ◽  
E. R. G. Eckert ◽  
R. J. Goldstein
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Reynolds Numbers ◽  
Hole Injection ◽  
Qualitative Information ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Density Ratios

Film cooling performance for injection through discrete holes in the endwall of a turbine blade is investigated. The effectiveness is measured at 60 locations in the region covered by injection. Three nominal blowing rates, two density ratios, and two approaching flow Reynolds numbers are examined. Analysis of the data reveals that even 60 locations are insufficient for the determination of the field of film cooling effectiveness with its strong local variations. Visualization of the traces of the coolant jets on the endwall surface, using ammonium-diazo-paper, provides useful qualitative information for the interpretation of the measurements, revealing the paths and interaction of the jets, which change with blowing rate and density ratio.

Negative Group Velocities in Continuous Structures

1957 ◽  
Vol 24 (4) ◽  
pp. 622-623
Author(s):  
S. H. Crandall
Keyword(s):  
Negative Group ◽  
Group Velocities

Film Cooling of the Gas Turbine Endwall by Discrete-Hole Injection

1994 ◽  
Author(s):  
M. Y. Jabbari ◽  
K. C. Marston ◽  
E. R. G. Eckert ◽  
R. J. Goldstein
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Reynolds Numbers ◽  
Hole Injection ◽  
Qualitative Information ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Density Ratios

Film cooling performance for injection through discrete holes in the endwall of a turbine blade is investigated. The effectiveness is measured at sixty locations in the region covered by injection. Three nominal blowing rates, two density ratios, and two approaching flow Reynolds numbers are examined. Analysis of the data reveals that even sixty locations are insufficient for the determination of the field of film cooling effectiveness with its strong local variations. Visualization of the traces of the coolant jets on the endwall surface, using ammonium-diazo-paper, provides useful qualitative information for the interpretation of the measurements, revealing the paths and interaction of the jets which change with blowing rate and density ratio.

scholarly journals The Mid-Infrared luminosity function of galaxies using the AKARI mid-infrared All-Sky Survey Catalogue

2011 ◽  
Vol 7 (S284) ◽  
pp. 228-230
Author(s):  
Y. Toba ◽  
S. Oyabu ◽  
H. Matsuhara ◽  
D. Ishihara ◽  
M. Malkan ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Density Ratio ◽  
Number Density ◽  
Limited Sample ◽  
Local Universe ◽  
Mid Infrared ◽  
Star Forming ◽  
Sky Survey

AbstractWe present the first determination of the 18 μm luminosity function (LF) of galaxies at 0.006 < z < 0.7 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected a 18 μm flux-limited sample of 243 galaxies from the catalogue in the SDSS spectroscopic region. We then classified the sample into four types; Seyfert 1 galaxies (including QSOs), Seyfert 2 galaxies, LINERs and Star-Forming galaxies using mainly [OIII]/Hβ vs. [NII]/Hα line ratios obtained from the SDSS.As a result of constructing Seyfert 1 and Seyfert 2 LFs, we found the following results; (i) the number density ratio of Seyfert 2s to Seyfert 1s is 3.98 ± 0.41 obtained from Sy1 and Sy2 LFs; this value is larger than the results obtained from optical LFs. (ii) the fraction of Sy2s in the entire AGNs may be anti-correlated with 18 μm luminosity. These results suggest that the torus structure probably depends on the mid-infrared luminosity of AGNs and most of the AGNs in the local Universe are obscured by dust.

scholarly journals Quantitative determination of the lowest density domain in major fault zones via medical X-ray computed tomography

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Akiyuki Iwamori ◽  
Hideo Takagi ◽  
Nobutaka Asahi ◽  
Tatsuji Sugimori ◽  
Eiji Nakata ◽  
...  
Keyword(s):  
Fault Zone ◽  
Atomic Number ◽  
Density Ratio ◽  
Effective Atomic Number ◽  
Fault Zones ◽  
Ct Number ◽  
Fault Rock ◽  
Major Fault ◽  
X Ray Computed

AbstractDetermination of the youngest active domains in fault zones that are not overlain by Quaternary sedimentary cover is critical for evaluating recent fault activity, determining the current local stress field, and mitigating the impacts of future earthquakes. Considering the exhumation of a fault zone, the youngest active domain in a fault zone is supposed to correspond to the activity at the minimum fault depth of a buried fault, such that the most vulnerable area, which possesses the lowest rock/protolith density ratio, is assumed to be indicative of this recent fault activity. However, it is difficult to measure the density of fault rocks and map the rock/protolith density ratio across a given fault zone. Here, we utilize medical X-ray computed tomography (CT), a non-destructive technique for observing and analyzing materials, to investigate the fault characteristics of several fault zones and their surrounding regions in Japan, and attempt to determine the lowest density domain of a given fault zone based on its CT numbers, which are a function of the density and effective atomic number of the fault rock and protolith. We first investigate the density, void ratio, and effective atomic number of active and inactive fault rocks, and their respective protoliths. We then calculate the CT numbers after reducing the beam-hardening effects on the rock samples and study the relationships among the CT number, density, and effective atomic number. We demonstrate that the density, effective atomic number, and CT number of the fault rock decrease as the youngest active zone, identified by outcrop observation, are approached, such that the region with the lowest CT number and rock/protolith density ratio defines the lowest density domain of a given fault zone. We also discuss the relationship between the lowest density domain and the youngest active domain in major fault zones and investigate the points to be considered when the youngest active domain is identified from the lowest density domain determined by the CT number.

Measurement of percent oxyhemoglobin in the microvasculature

1975 ◽  
Vol 38 (2) ◽  
pp. 321-327 ◽  
Author(s):  
R. N. Pittman ◽  
B. R. Duling
Keyword(s):  
Optical Density ◽  
Density Ratio ◽  
Optical Path Length ◽  
Optical Path ◽  
Cheek Pouch ◽  
Theoretical Treatment ◽  
Hamster Cheek Pouch ◽  
Particulate Suspensions ◽  
Optical Density Ratio

A new method is applied to the determination of percent oxyhemoglobin (percent saturation) in whole blood. The method is based on a theoretical treatment of light absorption and scattering by particulate suspensions and requires the measurement of optical densities (D) of blood at three closely spaced wavelengths. The optical density of red blood cell (RBC) suspensions was measured with a video microdensitometer and a linear relationship was found between percent saturation and the corrected optical density ratio, (D555 B)/(D546 B). For a given saturation, this ratio was independent of optical path length (12 mum-2 mm), hematocrit (3–50%), and RBC velocity (1.5–17 mm/s). The applicability to microvascular measurements has been assessed through the use of TV microdensitometry on micropipettes with flowing RBCs and on microvessels in the hamster cheek pouch.

scholarly journals Pulsed light beams in vacuum with superluminal and negative group velocities

2003 ◽  
Vol 67 (6) ◽  
Author(s):  
Miguel A. Porras ◽  
Isabel Gonzalo ◽  
Alessia Mondello
Keyword(s):  
Negative Group ◽  
Pulsed Light ◽  
Light Beams ◽  
Group Velocities
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