32,118 research outputs found
The NACA Three Component Accelerometer
A new instrument known as the NACA three component accelerometer is described in this note. This instrument was designed by the technical staff of the NACA for recording accelerations along three mutually perpendicular axes, and is of the same type as the NACA single component accelerometer with the addition of two springs and a few minor improvements such as a pump for filling the dash-pots and a convenient method for aligning the springs. This note includes a few records as well as photographs of the instrument itself
The N.A.C.A. Recording Tachometer and Angle of Attack Recorder
This note contains photos and descriptions of airplane flight apparatus for use in conjunction with a recording galvanometer. In measuring the angle of attack a variable resistance is used, being controlled by a vane in the airstream. Thus it is only necessary to measure the change of resistance
An Altitude Chamber for the Study and Calibration of Aeronautical Instruments
The design and construction of an altitude chamber, in which both pressure and temperature can be varied independently, was carried out by the NACA at the Langley Memorial Aeronautical Laboratory for the purpose of studying the effects of temperature and pressure on aeronautical research instruments. Temperatures from +20c to -50c are obtained by the expansion of CO2from standard containers. The chamber can be used for the calibration of research instruments under altitude conditions simulating those up to 45,000 feet. Results obtained with this chamber have a direct application in the design and calibration of instruments used in free flight research
Conical scan tracking system employing a large antenna
A conical scan tracking system for tracking spacecraft and distant radio sources is described. The system detects small sinusoidal modulation in received power from a source that is off target with a frequency equal to a very low scan rate, an amplitude proportional to angular deviation of the source from the target, and a phase directly related to the direction the source is off target. The sinusoid is digitally correlated with inphase and out-of-phase scan sinusoids to obtain azimuth/elevation and hour angle/declination signals which are digitally integrated over exactly one scan period to obtain correction signals for an antenna pointing subsystem
Conical-scan tracking with the 64-m-diameter antenna at goldstone
The theory and experimental work which demonstrated the feasibility of conical-scan tracking with a 64 m diameter paraboloid antenna is documented. The purpose of this scheme is to actively track spacecraft and radio sources continuously with an accuracy superior to that obtained by manual correction of the computer driven pointing. The conical-scan implementation gives increased tracking accuracy with X-band spacecraft signals, as demonstrated in the Mariner Venus/Mercury 1973 mission. Also, the high accuracy and ease of measurement with conical-scan tracking allow evaluation of systematic and random antenna tracking errors
A direct helicopter EM sea ice thickness inversion, assessed with synthetic and field data
Accuracy and precision of helicopter electromagneticHEM sounding are the essential parameters for HEM seaicethickness profiling. For sea-ice thickness research, thequality of HEM ice thickness estimates must be better than10 cm to detect potential climatologic thickness changes.Weintroduce and assess a direct, 1D HEM data inversion algorithmfor estimating sea-ice thickness. For synthetic qualityassessment, an analytically determined HEM sea-ice thicknesssensitivity is used to derive precision and accuracy. Precisionis related directly to random, instrumental noise, althoughaccuracy is defined by systematic bias arising fromthe data processing algorithm. For the in-phase component ofthe HEM response, sensitivity increases with frequency andcoil spacing, but decreases with flying height. For small-scaleHEM instruments used in sea-ice thickness surveys, instrumentalnoise must not exceed 5 ppm to reach ice thicknessprecision of 10 cm at 15-m nominal flying height. Comparableprecision is yielded at 30-m height for conventional explorationHEM systems with bigger coil spacings. Accuracylosses caused by approximations made for the direct inversionare negligible for brackish water and remain better than10 cm for saline water. Synthetic precision and accuracy estimatesare verified with drill-hole validated field data fromEast Antarctica, where HEM-derived level-ice thicknessagrees with drilling results to within 4%, or 2 cm
Dynamic precession damper for spin stabilized vehicles Patent
Dynamic precession damping of spin-stabilized vehicles by using rate gyroscope and angular acceleromete
Attitude orientation of spin-stabilized space vehicles Patent
Attitude orientation control of spin stabilized final stage space vehicles, using horizon scanner
Criteria for generalized macroscopic and mesoscopic quantum coherence
We consider macroscopic, mesoscopic and "S-scopic" quantum superpositions of
eigenstates of an observable, and develop some signatures for their existence.
We define the extent, or size of a superposition, with respect to an
observable \hat{x}, as being the range of outcomes of \hat{x} predicted by that
superposition. Such superpositions are referred to as generalized -scopic
superpositions to distinguish them from the extreme superpositions that
superpose only the two states that have a difference in their prediction
for the observable. We also consider generalized -scopic superpositions of
coherent states. We explore the constraints that are placed on the statistics
if we suppose a system to be described by mixtures of superpositions that are
restricted in size. In this way we arrive at experimental criteria that are
sufficient to deduce the existence of a generalized -scopic superposition.
The signatures developed are useful where one is able to demonstrate a degree
of squeezing. We also discuss how the signatures enable a new type of
Einstein-Podolsky-Rosen gedanken experiment.Comment: 15 pages, accepted for publication in Phys. Rev.
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