scholarly journals Immersion Factor of In-Water Radiance Sensors: Assessment for a Class of Radiometers

2006 ◽  
Vol 23 (2) ◽  
pp. 302-313 ◽  
Author(s):  
Giuseppe Zibordi
Keyword(s):  
Seawater Temperature ◽  
Fused Silica ◽  
Field Of View ◽  
Refractive Indices ◽  
Specific Class ◽  
Optical Components ◽  
Optical Window ◽  
Sensor Model ◽  
Half Angle ◽  
The Relationship

Abstract The spectral immersion factor of in-water radiance sensors If quantifies the effects of changes in the sensor's response when operated in water versus in air. The values of If are currently computed with a relationship derived from a basic sensor model, which only requires knowledge of the refractive indices of the water and the material constituting the sensor's optical window in contact herewith. Uncertainties in the computation of If are investigated in the 400–700-nm spectral range for a specific class of widely used multispectral radiometers. The analysis is made by comparing If values from the theoretical relationship currently in use with (i) If from a new relationship based on an extended sensor model accounting for the actual solid-angle field of view and the reflectance and transmittance of the external and internal optical components, and (ii) experimental If determined with sample radiometers having diverse optical windows made of materials with different refractive indices. Results highlight that the relationship derived from the basic sensor model introduces a 0.4% negative bias when applied to the considered class of radiometers having a fused silica optical window, a 13° in-air half-angle field of view, and an estimated detector reflectance of 0.15. Reference values of If for the specific class of radiometers, determined with the newly proposed relationship, are presented, and their dependence on seawater temperature and salinity is discussed.

scholarly journals The Moderating Effects of Group Work on the Relationship Between Motivation and Cognitive Load

2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Jamie Costley ◽  
Christopher Lange
Keyword(s):  
University Students ◽  
Cognitive Load ◽  
Group Work ◽  
Formal Learning ◽  
Specific Class ◽  
Moderating Effects ◽  
Formal Groups ◽  
Learning Groups ◽  
The Relationship ◽  
Cyber University

<p class="3">Semi-formal learning is used to describe learning that is directed towards the goals of a formal learning institution but outside of the learning structure of a specific class. Students studying online may form semi-formal groups to increase their knowledge of the content by interacting with other learners taking the same class. This study of cyber university students (n = 2042) involved looking at the relationship between semi-formal learning groups and levels of germane load.  Furthermore, this study sought to understand what role group work plays in moderating the relationship between motivation and germane load. This study found that highly motivated students had higher levels of germane load, and that group work negatively moderated that relationship. In other words, while all students benefited from group work, students with lower levels of motivation benefited more than students with high levels of motivation. This research fills an important gap by showing the value this type of group work can have for all learners, particularly those who may otherwise struggle.</p>

Laser damage performance of fused silica optical components measured on the beamlet laser at 351 nm

1999 ◽  
Author(s):  
Mark R. Kozlowski ◽  
Ron P. Mouser ◽  
Stephen M. Maricle ◽  
Paul J. Wegner ◽  
Timothy L. Weiland
Keyword(s):  
Fused Silica ◽  
Laser Damage ◽  
Optical Components

A Registration Method for Three-Dimensional Analysis of Bone Mineral Density in the Proximal Tibia

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Hugo Babel ◽  
Loïc Wägeli ◽  
Berke Sonmez ◽  
Jean-Philippe Thiran ◽  
Patrick Omoumi ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Bone Mineral ◽  
Proximal Tibia ◽  
Three Dimensional ◽  
Field Of View ◽  
3D Analysis ◽  
Mineral Density ◽  
Comprehensive Description ◽  
Registration Method ◽  
The Relationship

Abstract Although alterations in bone mineral density (BMD) at the proximal tibia have been suggested to play a role in various musculoskeletal conditions, their pathophysiological implications and their value as markers for diagnosis remain unclear. Improving our understanding of proximal tibial BMD requires novel tools for three-dimensional (3D) analysis of BMD distribution. Three-dimensional imaging is possible with computed tomography (CT), but computational anatomy algorithms are missing to standardize the quantification of 3D proximal tibial BMD, preventing distribution analyses. The objectives of this study were to develop and assess a registration method, suitable with routine knee CT scans, to allow the standardized quantification of 3D BMD distribution in the proximal tibia. Second, as an example of application, the study aimed to characterize the distribution of BMD below the tibial cartilages in healthy knees. A method was proposed to register both the surface (vertices) and the content (voxels) of proximal tibias. The method combines rigid transformations to account for differences in bone size and position in the scanner's field of view and to address inconsistencies in the portion of the tibial shaft included in routine CT scan, with a nonrigid transformation locally matching the proximal tibias. The method proved to be highly reproducible and provided a comprehensive description of the relationship between bone depth and BMD. Specifically it reported significantly higher BMD in the first 6 mm of bone than deeper in the proximal tibia. In conclusion, the proposed method offers promising possibilities to analyze BMD and other properties of the tibia in 3D.

scholarly journals XXXVI. On the influence of temperature on the refraction of light

1858 ◽  
Vol 148 ◽  
pp. 887-894 ◽  
Keyword(s):  
Field Of View ◽  
Refractive Indices ◽  
Narrow Slit ◽  
Joint Research ◽  
Influence Of Temperature ◽  
Fine Wire ◽  
Different Temperatures ◽  
Influence Of Temperature On ◽  
The Many ◽  
Cobalt Blue

Fraunhofer, in his original measurements of the fixed lines of the spectrum, noted the thermometer, and those who since his time have occupied themselves with the determi­nation of refractive indices, must have frequently noticed that changes of temperature affect the amount of refraction; yet of the many observations now on record, few have affixed to them the temperature at which they were made. Baden Powell has drawn out some refractive indices of the same substance taken at different temperatures, but remarks that the whole subject, both as to the facts of the case and as to their bear­ing on the theoretical formulæ, remains to be investigated. Among his beautiful researches on light, M. Jamin has recently published one or two experiments on refrac­tion, heat, and density; but, with this exception, he has left untouched the great question of the influence of temperature. Some years ago Baden Powell kindly lent his instrument to one of us for the pur­pose of investigating this question. It is described and figured in the Report of the British Association for 1839. It consists essentially of a small telescope moving on a circle graduated so finely, that by means of a vernier and magnifying glass it may be read to 10"; to ensure accuracy, there is a vernier at each end of the moveable arm: in front of the telescope are appliances for fixing any solid prism, or a hollow prism capable of containing liquids, in such a position that there may be seen through it a ray of light proceeding from a distant slit. The telescope may be moved till a fine wire fastened in the field of view is brought to coincide with any of Fraunhofer’s lines the prismatic spectrum thus obtained, and the angle indicated by the position of the telescope on the graduated circle may he read off. In our recent joint research, as we desired measure the positions of the extreme lines A and H, it was necessary to work with the full light of the sun; its mirrored image, therefore, was kept behind the narrow slit by a heliostat, and the eye was protected from the glare of the yellow ray by means of a cobalt-blue glass.

A Study of Some of the Meteorological Effects on Radio Propagation at 96.3 Mc between Richmond, Va. and Washington, D. C.

1954 ◽  
Vol 35 (2) ◽  
pp. 56-59 ◽  
Author(s):  
D. L. Randall
Keyword(s):  
Refractive Index ◽  
Field Strength ◽  
Meteorological Data ◽  
Radio Propagation ◽  
Refractive Indices ◽  
Wind Speeds ◽  
Meteorological Observations ◽  
Relationship Of ◽  
The Relationship ◽  
Meteorological Effects

This study was made to investigate the relationship of surface meteorological data and corresponding surface refractive indices to radio field strengths in the FM frequency band. For meteorological observations during which the wind speeds were equal to or greater than 10 mph, and when fronts, low overcast clouds (less than 5000 ft), rain, thunderstorms and fogs were excluded, a 0.70 correlation coefficient was found between hourly surface refractive index and hourly median field strength over a Washington-Richmond path at a frequency of 96.3 Mc.

Sensing Refractive Indices of Fluids by Wavelength-Tunable Laser and Novel Multi-stage Directional Couplers

2017 ◽  
Vol 38 (2) ◽  
Author(s):  
Ruei-Chang Lu ◽  
Keh-Yi Lee
Keyword(s):  
Refractive Index ◽  
Optical Power ◽  
Tunable Laser ◽  
Liquid Solution ◽  
Refractive Indices ◽  
Directional Couplers ◽  
Wavelength Tunable ◽  
Multi Stage ◽  
Maximal Output ◽  
The Relationship

AbstractIn this work, the authors propose a modified type of multi-stage directional couplers and combine it with a wavelength-tunable laser to measure the refractive index of an undetermined biochemical liquid/solution. Tuning the wavelength of the laser incident on the modified multi-stage directional couplers, the relationship between the wavelength corresponding to the maximal output optical power and the refractive index of the unknown fluid has been obtained.

Investigation on the Reaction of Refractories with 16MnRE Steel

2013 ◽  
Vol 575-576 ◽  
pp. 423-426
Author(s):  
Dong Wang ◽  
Ye Feng Guan
Keyword(s):  
Rare Earth ◽  
Fused Silica ◽  
High Alumina ◽  
Zircon Nozzle ◽  
Nozzle Blockage ◽  
Al Addition ◽  
The Relationship

When teeming rare earth treated steels the nozzle blockage occurred so frequently that seriously interferes the application of RE in steels. In this study we tried to investigate the relationship between the wettablility of 16MnRE steel and nozzle materials. The results showed that the weakest wettability of steel liquid was observed on fused silica among the six nozzle materials. Next came zircon and high-alumina nozzle. It has no obvious difference between the 16MnRE steels when final deoxidized containing and not containing Al addition. The wettability of 10Ti steel was weaker than 16MnRE steels on zircon nozzle. The clay nozzle was corroded by the precipitate from steel liquid.

Iron-bearing smectites: a revised relationship between structural Fe, b cell edge lengths and refractive indices

Clay Minerals ◽  
2013 ◽  
Vol 48 (1) ◽  
pp. 97-103 ◽  
Author(s):  
M. Heuser ◽  
P. Andrieux ◽  
S. Petit ◽  
H. Stanjek
Keyword(s):  
Refractive Index ◽  
B Cell ◽  
Edge Length ◽  
Refractive Indices ◽  
Cell Edge ◽  
Turbidity Method ◽  
Structural Iron ◽  
First Time ◽  
The Relationship ◽  
Iron Bearing

AbstractStructural iron in smectites correlates with the cell edge length b and increases the refractive index. The cell edge length b is usually obtained from the position of the (060) reflection, but in this work we show that such b values differ from the values obtained from Rietveld fits because contributions from (hkl) reflections shift the position of the (060) reflection. The correlation between Fe and cell edge length b was significant (r2 > 0.99); the relationship is b [Å] = 8.9977(0.0035) + 0.1117(0.0032) × Fetot. Furthermore, we present for the first time measurements of the refractive index n of Fe-bearing smectites, applying a recently published turbidity method (Weidler & Friedrich, 2007). The refractive index correlates both with structural iron (r2 = 0.64) and with b (r2 = 0.94).

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