Assessment of MODIS scan mirror reflectance changes on-orbit

2008 ◽  
Author(s):  
X. Xiong ◽  
A. Wu ◽  
A. Angal
Keyword(s):  
Mirror Reflectance

The Interrelation between Recurrent and Capital Costs in a Solar Thermal Process Heat System

1981 ◽  
Vol 103 (3) ◽  
pp. 241-243
Author(s):  
L. L. Lukens ◽  
W. P. Schimmel
Keyword(s):  
Energy Cost ◽  
Solar Collector ◽  
Alternative Energy ◽  
Market Penetration ◽  
Heat Temperature ◽  
Capital Costs ◽  
Heat System ◽  
Process Heat ◽  
Cleaning Cost ◽  
Mirror Reflectance

The effect of operation and maintenance (O&M) costs on energy produced by solar collector systems is crucial to the market penetration of solar process heat as an alternative energy source. In the present paper, a particular O&M operation, regular collector cleaning, is considered in order to determine its effect upon annualized life cycle energy cost. A first-order model of mirror reflectance degradation as a function of time is constructed from experimental data taken at Albuquerque, N.M. This is used as input to a systems optimization model of a line-focus solar collector process heat installation. The energy cost variation is considered as a function of cleaning cost per unit of collector aperture and cleaning interval. Results are presented for a process heat temperature of 177°C.

Heliostat Operation at the Central Receiver Test Facility, 1978–1980

1982 ◽  
Vol 104 (3) ◽  
pp. 133-138 ◽  
Author(s):  
J. T. Holmes
Keyword(s):  
Test Facility ◽  
Total Power ◽  
Peak Intensity ◽  
Central Receiver ◽  
Operations And Maintenance ◽  
Solar Noon ◽  
Mirror Reflectance ◽  
Targeting Accuracy

The operations and maintenance data and conclusions presented in this report are for the 222 heliostats that have been in use at the Central Receiver Test Facility (CRTF) from 1978 through 1980. The CRTF beam produces a total power of 5.5 MWth and a peak intensity of 2250 kW/m2 near solar noon. Improvements in the targeting accuracy have been made. The mirror reflectance is maintained near 80 percent by cleaning with rain or snow. The CRTF heliostats logged almost 300,000 operating hrs by the end of 1980.

scholarly journals Resonance-enhanced spectral funneling in Fabry–Perot resonators with a temporal boundary mirror

Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Kanghee Lee ◽  
Junho Park ◽  
Seojoo Lee ◽  
Soojeong Baek ◽  
Jagang Park ◽  
...  
Keyword(s):  
Continuous Time ◽  
Boundary Effect ◽  
Energy Conversion Efficiency ◽  
Translational Symmetry ◽  
Specific Time ◽  
Abrupt Increase ◽  
Spectral Content ◽  
Fabry Perot ◽  
Temporal Boundary ◽  
Mirror Reflectance

Abstract A temporal boundary refers to a specific time at which the properties of an optical medium are abruptly changed. When light interacts with the temporal boundary, its spectral content can be redistributed due to the breaking of continuous time-translational symmetry of the medium where light resides. In this work, we use this principle to demonstrate, at terahertz (THz) frequencies, the resonance-enhanced spectral funneling of light coupled to a Fabry–Perot resonator with a temporal boundary mirror. To produce a temporal boundary effect, we abruptly increase the reflectance of a mirror constituting the Fabry–Perot resonator and, correspondingly, its quality factor in a step-like manner. The abrupt increase in the mirror reflectance leads to a trimming of the coupled THz pulse that causes the pulse to broaden in the spectral domain. Through this dynamic resonant process, the spectral contents of the input THz pulse are redistributed into the modal frequencies of the high-Q Fabry–Perot resonator formed after the temporal boundary. An energy conversion efficiency of up to 33% was recorded for funneling into the fundamental mode with a Fabry–Perot resonator exhibiting a sudden Q-factor change from 4.8 to 48. We anticipate that the proposed resonance-enhanced spectral funneling technique could be further utilized in the development of efficient mechanically tunable narrowband terahertz sources for diverse applications.

Bragg Mirror Reflectance in a VCSEL Scanning Optical Microscope

1997 ◽  
pp. 807-812
Author(s):  
R. R. Burton ◽  
M. S. Stern ◽  
P. C. Kendall ◽  
P. N. Robson ◽  
T. M. Benson
Keyword(s):  
Optical Microscope ◽  
Bragg Mirror ◽  
Mirror Reflectance

Mirror Reflectance Spectrum Modeling of Smooth Samples

2013 ◽  
Vol 33 (6) ◽  
pp. 0612008
Author(s):  
邹喜仁 Zou Xiren ◽  
白璐 Bai Lu ◽  
吴振森 Wu Zhensen
Keyword(s):  
Reflectance Spectrum ◽  
Spectrum Modeling ◽  
Mirror Reflectance

scholarly journals Revolutionizing Spaceflight: A Study on Electric Propulsion and Air-Breathing MPDs

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Ian McKinney ◽  
John Murnan
Keyword(s):  
Experimental Study ◽  
Electric Propulsion ◽  
Liquid Fuel ◽  
Specific Impulse ◽  
Atmospheric Conditions ◽  
Air Breathing ◽  
Rocket Propulsion ◽  
Hall Effect Thrusters ◽  
Quasi Experimental ◽  
Mirror Reflectance

Modern liquid-fuel rocket propulsion harbors a number of great limitations. Among those is the weight of fuel, which makes up more than 90% of the mass of the SpaceX Falcon 9 (NASA, 2018). Electric propulsion has been used for decades as an alternative to liquid-fuel rockets due to low propellant requirements and high specific impulse. Although electric thrusters have strictly been used in non-atmospheric conditions, recent innovations attempt to expand its use to airspace. This quasi-experimental study focuses on the creation of an air-breathing magnetoplasmadynamic (MPD) thruster, with attempts being made to maximize the efficiency of the engine. Immense safety concerns prevented testing from occurring after the engine was built. However, the estimated performance of the built MPD is compared to a multitude of existing forms of electric propulsion, from Hall-effect thrusters to electrodynamic tethers. The concluding evidence suggests that air-breathing MPDs are not currently viable, high-power photon thrusters being of greater use in atmospheric conditions. Further research focusing on decreasing atmospheric breakdown voltage and increasing mirror reflectance of photon thrusters is suggested.

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