Aerospace & Aviation

Space chamber emittance measurements

Spectral reflectance by an integrating sphere reflectometer

Cavitation erosion on turbine blades - oscillator

Void fraction measurements in a cavitating venturi

Separation and heat transfer and pressure distribution on cone-cylinder-flare configurations

Convergent and divergent illumination with plane gratings

Preliminary reverse impulse of storms - analysis of atmospheric current functions

Concepts from statistical filter theory are applied to the problem of in-flight determination of the position and velocity of a space vehicle for the purposes of midcourse guidance. The source of information is assumed to be an arbitrary sequence of measurements of any desired set of "observables" (e.g., space angles), the measurements being corrupted by additive errors so that the position and velocity are never known perfectly. A state transition approach is employed which leads naturally to a computational scheme that is readily implemented by a digital computer. The scheme can be regarded as a dynamical time-varying filter which weights the incoming observations in an optimal sense for use in producing an up-to-date optimal estimate of position and velocity. The advantages of the scheme are (1) it provides the best possible estimate (minimum error) based upon ensemble statistics of injection conditions and measurement errors; (2) it is extremely versatile, not requiring adherence to a predetermined observation schedule or reference trajectory; and (3) the computations are sufficiently simple to be practical in an on-board computer. A digital computer simulation of the proposed system is employed to demonstrate the feasibility of an all on-board system and to illustrate the performance attainable in a hypothetical physical situation.

Relative efficiency of photosynthesis in the course of chlorella cell development

Feedback control system

Spectrum of lightning in the venus atmosphere. problems of selenodetic photogrammetry. drawings of lunar limb areas. topocentric librations.

Microparticle hypervelocity impact of cosmic dust from ranger i

Hypervelocity impact craters in rock

Detection of extraterrestrial life - optical rotary dispersion

Closed-form solutions of the one-dimensional heat-conduction equations for the flow of heat into a plate with a laminar boundary layer have been obtained for a configuration entering a planetary atmosphere with constant velocity and negative entry angle. The atmospheric density was assumed to obey an exponential law and the temperature was assumed constant initially. The solution is in the form of a Fourier series expansion which, for most practical applications, can be approximated by retaining only one term of the expression. The solution applies to the initial part of the entry before the maximum heating conditions are encountered.