Effects of three transmission models in the rotational water-vapor band on radiance calculations and constituent inferences

Transmission model effects on water vapor mixing ratios and radiance calculations for infrared horizon scanner

A Vibratory Acoustic Gyroscope

No abstract availabl

Seismic Design of Earth Retaining Structures

Recent experiments, field observations and theoretical numerical studies are summarized: Where the simple conditions assumed by the Mononobe-Okabe theory are reproduced. ln tests, predictions and observations agree well. However, a retaining structure and surrounding soil are a complex dynamic system and behavior is far from simple. Emphasis has shifted somewhat away from dynamic stresses toward evaluation of residual displacements. With a good understanding of actual behavior, traditional methods may still be used except for large and unusual structures. The largest unknowns concern the behavior of cohesive soils and moderately dense to dense saturated sands

Application of Spectral Solution and Neural Network Techniques in Plasma Modeling for Electric Propulsion

A solver for Poisson\u27s equation was developed using the Radix-2 FFT method first invented by Carl Friedrich Gauss. Its performance was characterized using simulated data and identical boundary conditions to those found in a Hall Effect Thruster. The characterization showed errors below machine-zero with noise-free data, and above 20% noise-to-signal strength, the error increased linearly with the noise. This solver can be implemented into AFRL\u27s plasma simulator, the Thermophysics Universal Research Framework (TURF) and used to quickly and accurately compute the electric field based on charge distributions. The validity of a machine learning approach and data-based complex system modeling approach was demonstrated. To this end, several multilayer perceptrons were created and validated against AFRL-provided Hall Thruster test data, with two networks showing mean error below 1% and standard deviations below 10%. These results, while not ready for implementation as a replacement for lookup tables, strongly suggest paths for future work and the development of networks that would be acceptable in such a role, saving both RAM space and time in plasma simulations

Mechanization of and experience with a triplex fly-by-wire backup control system

A redundant three-axis analog control system was designed and developed to back up a digital fly-by-wire control system for an F-8C airplane. Forty-two flights, involving 58 hours of flight time, were flown by six pilots. The mechanization and operational experience with the backup control system, the problems involved in synchronizing it with the primary system, and the reliability of the system are discussed. The backup control system was dissimilar to the primary system, and it provided satisfactory handling through the flight envelope evaluated. Limited flight tests of a variety of control tasks showed that control was also satisfactory when the backup control system was controlled by a minimum-displacement (force) side stick. The operational reliability of the F-8 digital fly-by-wire control system was satisfactory, with no unintentional downmodes to the backup control system in flight. The ground and flight reliability of the system's components is discussed

Mechanization of and experience with a triplex fly-by-wire backup control system

A redundant three axis analog control system was designed and developed to back up a digital fly by wire control system for an F-8C airplane. The mechanization and operational experience with the backup control system, the problems involved in synchronizing it with the primary system, and the reliability of the system are discussed. The backup control system was dissimilar to the primary system, and it provided satisfactory handling through the flight envelope evaluated. Limited flight tests of a variety of control tasks showed that control was also satisfactory when the backup control system was controlled by a minimum displacement (force) side stick. The operational reliability of the F-8 digital fly by wire control system was satisfactory, with no unintentional downmodes to the backup control system in flight. The ground and flight reliability of the system's components is discussed

Effect of sampling rate and record length on the determination of stability and control derivatives

Flight data from five aircraft were used to assess the effects of sampling rate and record length reductions on estimates of stability and control derivatives produced by a maximum likelihood estimation method. Derivatives could be extracted from flight data with the maximum likelihood estimation method even if there were considerable reductions in sampling rate and/or record length. Small amplitude pulse maneuvers showed greater degradation of the derivative maneuvers than large amplitude pulse maneuvers when these reductions were made. Reducing the sampling rate was found to be more desirable than reducing the record length as a method of lessening the total computation time required without greatly degrading the quantity of the estimates

A technique to infer atmospheric water-vapor mixing ratio from measured horizon radiance profiles

Computer program used to infer atmospheric water-vapor mixing ratio from measured horizon radiance profile

The new HiVIS spectropolarimeter and spectropolarimetric calibration of the AEOS telescope

We designed, built, and calibrated a new spectropolarimeter for the HiVIS spectrograph (R 12000-49000) on the AEOS telescope. We also did a polarization calibration of the telescope and instrument. We will introduce the design and use of the spectropolarimeter as well as a new data reduction package we have developed, then discuss the polarization calibration of the spectropolarimeter and the AEOS telescope. We used observations of unpolarized standard stars at many pointings to measure the telescope induced polarization and compare it with a Zemax model. The telescope induces polarization of 1-6% with a strong variation with wavelength and pointing, consistent with the altitude and azimuth variation expected. We then used scattered sunlight as a linearly polarized source to measure the telescopes spectropolarimetric response to linearly polarized light. We then made an all-sky map of the telescope's polarization response to calibrate future spectropolarimetry.Comment: PASP 118, June 200

Can Associations Have Priority over Fannie or Freddie?

An association’s six-month lien priority is sometimes termed a “superlien,” but there is nothing particularly “super” about it; the statute simply provides that an association has a lien with priority over the first mortgage, much like the lien of property taxes in nearly all states. An association’s total lien is effectively split into two components: a lien before the first mortgage for six months of assessments and a lien junior to the first mortgage for any delinquent assessment amount over six months’ worth. In this way, section 3-116 was intended to strike “an equitable balance between the need to enforce collection of unpaid assessments and the obvious necessity for protecting the priority of the security interests of lenders.” This careful balance is in jeopardy, however, as the result of challenges from the Federal Housing Finance Authority (FHFA), claiming that associations cannot foreclose on assessment liens without the FHFA’s consent if the property is subject to mortgages held by Fannie Mae or Freddie Mac. After explaining the basis for the FHFA’s novel defense, this article gives several reasons why courts should reject the defense