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Infrared Radiation From Explosions in a Spark-Ignition Engine

Description: This report presents the results of an investigation to determine the variations in intensity and spectral distribution of the radiant energy emitted by the flames during normal and knocking explosions in an engine. Radiation extending into the infrared was transmitted by a window of fluorite, placed either near the spark plug or over the detonation zone at opposite ends of the combustion chamber. Concave, surface-silvered mirrors focused the beam, first at the slit of a stroboscope which opened for about 2 degrees of crank angle at any desired point in the engine cycle, and then upon the target of a sensitive thermocouple for measuring radiation intensity.
Date: February 27, 1934
Creator: Marvin, Charles F., Jr.; Caldwell, Frank R. & Steele, Sydney
Partner: UNT Libraries Government Documents Department

Application of Thermal Imagery and Aerial Photography to Hydrologic Studies of Karst Terrane in Missouri

Description: From abstract: Planning waste-disposal facilities and impoundments is complicated by karst carbonate terrane in the Ozarks. Thermal imagery (8-13 micrometer wavelength) and color infrared photography aid in identifying losing streams, sinkholes and hydrologic conditions encouraging collapse. Imagery and photography were acquired in Greene and Reynold Counties, Mo., in March 1972 and June 1973. Differences in thermal levels correlating with losing and gaining reaches of Logan Creek valley, Reynolds County, were not visually apparent in predawn March imagery but statistical analysis of predawn magnetic-tape data indicated greater variance in emitted energy from the losing reach than from the gaining reach.
Date: September 1977
Creator: Harvey, E. J.; Williams, J. H. & Dinkel, T. R.
Partner: UNT Libraries Government Documents Department


Description: Normal-coordinate calculations for the S/sub 8/ molecule were revised by use of new far-infrared spectral data and a more elaborate potential function. Representation of the observed frequencies required that the basic Urey--Bradley field be supplemented with an extra quadratic cross-term between adjacent S--S bonds. (auth)
Date: January 1, 1962
Creator: Kruse, F. H.; Scott, D. W. & McCullough, J. P.
Partner: UNT Libraries Government Documents Department

Long wavelength infrared camera (LWIRC): a 10 micron camera for the Keck Telescope

Description: The Long Wavelength Infrared Camera (LWIRC) is a facility instrument for the Keck Observatory designed to operate at the f/25 forward Cassegrain focus of the Keck I telescope. The camera operates over the wavelength band 7-13 {micro}m using ZnSe transmissive optics. A set of filters, a circular variable filter (CVF), and a mid-infrared polarizer are available, as are three plate scales: 0.05``, 0.10``, 0.21`` per pixel. The camera focal plane array and optics are cooled using liquid helium. The system has been refurbished with a 128 x 128 pixel Si:As detector array. The electronics readout system used to clock the array is compatible with both the hardware and software of the other Keck infrared instruments NIRC and LWS. A new pre-amplifier/A-D converter has been designed and constructed which decreases greatly the system susceptibility to noise.
Date: May 1, 1998
Creator: Wishnow, E.H.; Danchi, W.C.; Tuthill, P.; Wurtz, R.; Jernigan, J.G. & Arens, J.F.
Partner: UNT Libraries Government Documents Department

Optimization of Blazed Quantum Grid Infrared Photodetectors

Description: In a quantum grid infrared photodetector (QGIP), the active multiple quantum well material is patterned into a grid structure. The purposes of the grid are on the one hand to create additional lateral electron confinement and on the other to convert part of the incident light into parallel propagation. With these two unique functions, a QGIP allows intersubband transition to occur in all directions. In this work, we focused on improving the effectiveness of a QGIP in redirecting the propagation of light using a blazed structure. The optimization of the grid parameters in terms of the blaze angle and the periodicity was performed by numerical simulation using the modal transmission-line theory and verified by experiment. With a blazed structure, the sensitivity of a QGIP can be improved by a factor of 1.8 compared with a regular QGIP with rectangular profiles.
Date: July 7, 1999
Creator: Chen, C.J.; Choi, K.K.; Jiang, M.; Rokhinson, L.P.; Tamir, T.; Tsui, D.C. et al.
Partner: UNT Libraries Government Documents Department

Monsters and babies from the first/IRAS survey

Description: Radio continuum emission at cm wavelengths is relatively little affected by extinction. When combined with far-infrared (FIR) surveys this provides for a convenient and unbiased method to select (radio-loud) AGN and starbursts deeply embedded in gas and dust-rich galaxies. Such radio-selected FIR samples are useful for detailed investigations of the complex relationships between (radio) galaxy and starburst activity, and to determine whether ULIRGs are powered by hidden quasars (monsters) or young stars (babies). We present the results of a large program to obtain identifications and spectra of radio-sleected, optically faint IRAS/FSC objects using the FIRST/VLA 20 cm survey (Becker, White and Helfand 1995). These objects are all radio-'quiet' in the sense that their radio power/FIR luminosities follow the well-known radio/FIR relationship for star forming galaxies. We compare these results to a previous study by our group of a sample of radio-'loud' IRAS/FSC ULIRGs selected from the Texas 365 MHz survey (Douglas et al. 1996). Many of these objects also show evidence for dominant, A-type stellar populations, as well as high ionization lines usually associated with AGN. These radio-loud ULIRGs have properties intermediate between those of starbursts and quasars, suggesting a possibile evolutionary connection. Deep Keck spectroscopic observations of three ULIRGs from these samples are presented, including high signal-to-noise spectropolarimetry. The polarimetry observations failed to show evidence of a hidden quasar in polarized (scattered) light in the two systems in which the stellar light was dominated by A-type stars. Although observations of a larger sample would be needed to allow a general conclusion, our current data suggest that a large fraction of ULIRGs may be powered by luminous starbursts, not by hidden, luminous AGN (quasars). While we used radio-selected FIR sources to search for evidence of a causal AGN/starburst connection, we conclude our presentation with a dramatic example of an AGN/starburst ...
Date: February 16, 1999
Creator: Van Bruegel, W J M
Partner: UNT Libraries Government Documents Department


Description: During the period, March 1997 – February 2006, the Principal Investigator and his research team co-authored 47 peer-reviewed papers and presented, at least, 138 papers at conferences, meetings, and workshops that were supported either in whole or in part by this agreement. We developed a state-of-the-art satellite cloud processing system that generates cloud properties over the Atmospheric Radiation (ARM) surface sites and surrounding domains in near-real time and outputs the results on the world wide web in image and digital formats. When the products are quality controlled, they are sent to the ARM archive for further dissemination. These products and raw satellite images can be accessed at http://cloudsgate2.larc.nasa.gov/cgi-bin/site/showdoc?docid=4&cmd=field-experiment-homepage&exp=ARM and are used by many in the ARM science community. The algorithms used in this system to generate cloud properties were validated and improved by the research conducted under this agreement. The team supported, at least, 11 ARM-related or supported field experiments by providing near-real time satellite imagery, cloud products, model results, and interactive analyses for mission planning, execution, and post-experiment scientific analyses. Comparisons of cloud properties derived from satellite, aircraft, and surface measurements were used to evaluate uncertainties in the cloud properties. Multiple-angle satellite retrievals were used to determine the influence of cloud structural and microphysical properties on the exiting radiation field.
Date: June 28, 2013
Creator: Minnis, Patrick
Partner: UNT Libraries Government Documents Department

Characterizing the emissivity of materials under dynamic compression (final report for LDRD project 79877).

Description: Temperature measurements are crucial to equation of state development, but difficult to perform reliably. In the case of infrared pyrometry, a large uncertainty comes from the fact that sample emissivity (the deviation from a blackbody) is unknown. In this project, a method for characterizing the emissivity of shocked materials was developed. By coupling infrared radiation from the National Synchrotron Light Source to a gas gun system, broad spectrum emissivity changes were studied to a peak stress of 8 GPa. Emissivity measurements were performed on standard metals (Al, Cr, Cu, and Pt) as well as a high emissivity coating developed at Sandia.
Date: October 1, 2007
Creator: Dolan, Daniel H.
Partner: UNT Libraries Government Documents Department

Degenerate four-wave mixing and phase conjugation in a collisional plasma

Description: Although degenerate four-wave mixing (DFWM) has many practical applications in the visible regime, no successful attempt has been made to study or demonstrate DFWM for wavelengths longer than 10..mu..m. Recently, Steel and Lam established plasma as a viable DFWM and phase conjugation (PC) medium for infrared, far-infrared, and microwaves. However, their analysis is incomplete since collisional effects were not included. Using a fluid description, our results demonstrate that when collisional absorption is small and the collisional mean-free path is shorter than the nonlinear density grating scale length, collisional heating generates a thermal force which substantially enhances the phase conjugate reflectivity. When the collisional attenuation length becomes comparable to the length of the plasma, the dominant effect is collisional absorption of the pump waves. Numerical estimates of the phase conjugate reflectivity indicate that for modest power levels, gains greater than or equal to1 are possible in the submillimeter to centimeter wavelength range. This suggests that a plasma is a viable PC medium at those long wavelengths. In addition, doubly DFWM is discussed.
Date: June 1, 1986
Creator: Federici, J.F. & Mansfield, D.K.
Partner: UNT Libraries Government Documents Department

Germanium blocked impurity band far infrared detectors

Description: The infrared portion of the electromagnetic spectrum has been of interest to scientist since the eighteenth century when Sir William Herschel discovered the infrared as he measured temperatures in the sun's spectrum and found that there was energy beyond the red. In the late nineteenth century, Thomas Edison established himself as the first infrared astronomer to look beyond the solar system when he observed the star Arcturus in the infrared. Significant advances in infrared technology and physics, long since Edison's time, have resulted in many scientific developments, such as the Infrared Astronomy Satellite (IRAS) which was launched in 1983, semiconductor infrared detectors for materials characterization, military equipment such as night-vision goggles and infrared surveillance equipment. It is now planned that cooled semiconductor infrared detectors will play a major role in the ''Star Wars'' nuclear defense scheme proposed by the Reagan administration.
Date: April 1, 1988
Creator: Rossington, C.S.
Partner: UNT Libraries Government Documents Department

Far infrared chemical lasers. Technical progress report No. 3, August 1, 1976--July 31, 1977. [HCN]

Description: Laser oscillation at 337 and 311 ..mu..m has been obtained from HCN molecules prepared in vibrationally excited states by the reaction between cyanogen radicals and hydrogen molecules. It has likewise been observed in HCN raised to an electronically excited state by flash photolysis. The characteristics of the pulsed output are quite different in the two cases and beginnings have been made on experiments to probe the pumping and energy transfer kinetics. The rate determining step is not the reaction rate, but rather some relaxation process that eventually channels the excitation into the upper lasing state of one quantum each of CN stretch and bend. Detailed studies of the relative intensities of pure rotational lasing in OH and OD have been made. The rotational inversions are produced by rare gas-aided, adiabatic energy conversion from vibrational to rotational excitation. The process is rapid in comparison to rotational collisional relaxation. Using transfer parameters from the ''information theoretic'' analysis (R. D. Levine) computations have been made which reproduce the results in detail, providing support for the pumping mechanism proposed, and the applicability of the theory. Preliminary work on NH (from the HN/sub 3/ photolysis) has opened up extremely interesting questions concerning the electronic states of the nascent molecules and the subsequently lasing molecules. Pure rotational laser action in at least two states (one singlet and one triplet) has been measured.
Date: August 1, 1977
Creator: Robinson, D. W.
Partner: UNT Libraries Government Documents Department

Synthesis and properties of Chitosan-silica hybrid aerogels

Description: Chitosan, a polymer that is soluble in dilute aqueous acid, is derived from chitin, a natural polyglucosamide. Aquagels where the solid phase consists of both chitosan and silica can be easily prepared by using an acidic solution of chitosan to catalyze the hydrolysis and condensation of tetraethylorthosilicate. Gels with chitosan/TEOS mass ratios of 0.1-1.1 have been prepared by this method. Standard drying processes using CO{sub 2} give the corresponding aerogels. The amount of chitosan in the gel plays a role in the shrinkage of the aerogel during drying. Gels with the lowest chitosan/silica ratios show the most linear shrinkage, up to 24%, while those with the highest ratios show only a 7% linear shrinkage. Pyrolysis at 700 C under nitrogen produces a darkened aerogel due to the thermal decomposition of the chitosan, however, the aerogel retains its monolithic form. The pyrolyzed aerogels absorb slightly more infrared radiation in the 2-5 {micro}m region than the original aerogels. B.E.T. surface areas of these aerogels range from 470-750 m{sup 2}/g. Biocompatibility screening of this material shows a very high value for hemolysis, but a low value for cytotoxicity.
Date: June 1, 2001
Creator: Ayers, Michael R. & Hunt, Arlon J.
Partner: UNT Libraries Government Documents Department

Imagery from Infrared Scanning of the East and Southwest Rift Zones of Kilauea and the Lower Portion of the Southwest Rift Zone of Mauna Loa, Island of Hawaii

Description: From July 31 through August 4, 1973 night time flights for obtaining infrared imagery along the east and southwest rift zones of Kilauea and the southwest rift zone of Mauna Loa were undertaken on the island of Hawaii. Flights were also made on Hualalai and Kohala volcanoes but because of inconclusive results, they are not included in this report. Ground control stations had been established during daylight hours several days prior to starting the flight program. Students stationed at the ground central points guided the aircraft on predetermined flight paths by the use of directional lights which were visible to the plane's navigator. Results of the infrared scanning program are considered to be very successful. Events leading up to the final imagery on 8 x 10 color prints are discussed. The sum of $23,900 was designated by the NSF to be expended on aerial photogeologic work on the Hawaii Geothermal Project. Infrared scanning was the only aerial technique employed in this phase.
Date: January 1, 1974
Creator: Abbott, A. T.
Partner: UNT Libraries Government Documents Department

An Evaluation of the Nonlinearity Correction Applied to Atmospheric Emitted Radiance Interferometer (AERI) Data Collected by the Atmospheric Radiation Measurement Program

Description: Mercury Cadmium Telluride (MCT) detectors provide excellent sensitivity to infrared radiation and are used in passive infrared remote sensors such as the Atmospheric Emitted Radiance Interferometer (AERI). However, MCT detectors have a nonlinear response and thus this nonlinearity must be characterized and corrected to provide accurate infrared radiance observations. This paper discusses the significance of the nonlinearity correction applied to AERI data and its impacts on the parameters retrieved from the AERI spectra. It also evaluates the accuracy of the scheme used to determine the nonlinearity of the MCT detectors used in the Atmospheric Radiation Measurement (ARM) Program’s AERIs.
Date: September 1, 2004
Creator: Turner, D. D.; Revercomb, H. E.; Knuteson, R. O.; Dedecker, R. G. & Feltz, W. F.
Partner: UNT Libraries Government Documents Department

Solar and Infrared Radiation Station (SIRS) Handbook

Description: The Solar Infrared Radiation Station (SIRS) provides continuous measurements of broadband shortwave (solar) and longwave (atmospheric or infrared) irradiances for downwelling and upwelling components. The following six irradiance measurements are collected from a network of stations to help determine the total radiative flux exchange within the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility: • Direct normal shortwave (solar beam) • Diffuse horizontal shortwave (sky) • Global horizontal shortwave (total hemispheric) • Upwelling shortwave (reflected) • Downwelling longwave (atmospheric infrared) • Upwelling longwave (surface infrared)
Date: July 1, 2005
Creator: Stoffel, T
Partner: UNT Libraries Government Documents Department

Proof-Of-Principle Experiment for Laser-Driven Acceleration of Relativistic Electrons in a Semi-Infinite Vacuum

Description: We recently achieved the first experimental observation of laser-driven particle acceleration of relativistic electrons from a single Gaussian near-infrared laser beam in a semi-infinite vacuum. This article presents an in-depth account of key aspects of the experiment. An analysis of the transverse and longitudinal forces acting on the electron beam is included. A comparison of the observed data to the acceleration viewed as an inverse transition radiation process is presented. This is followed by a detailed description of the components of the experiment and a discussion of future measurements.
Date: March 1, 2006
Creator: Plettner, T.; Byer, R.L.; /Stanford U., Phys. Dept.; Colby, E.; Cowan, B.; Sears, C.M.S. et al.
Partner: UNT Libraries Government Documents Department