Viking and STP P78-2 electrostatic charging designs and testing

The design provisions of the Viking and the P78-2 (SCATHA) vehicles and a mathematical analysis of the effect of arcing on typical interface circuits are given. Results of verification testing of the analysis are presented as well as vehicle testing for tolerance to arcing

Mariner Mars absorptivity standard

Mariner 4 space probe absorptivity standard used to measure solar absorptance of temperature control surface

Measuring wheel/rail contact stresses using ultrasound

The investigation of contact area and pressure distribution in a wheel/rail contact is essential information required in fatigue and wear calculations to determine design life, regrinding requirements, and maintenance schedules. The aim of this work was to use ultrasound to non-destructively determine wheel/rail contact pressures. Three different contacts were investigated those resulting from; un-used, sand damaged, and worn wheel/rail specimens. A wheel/rail interface behaves like a spring. If the pressure is high the interface is very stiff, with few air gaps, and allows the transmission of an ultrasonic sound wave. If the pressure is low, interfacial stiffness is low and almost all the ultrasound is reflected. A spring model was used to determine maps of contact stiffness from wheel/rail ultrasonic reflection data. Pressure was then determined using a calibration experiment. Separate calibrations were performed for each of the three sets of wheel/rail specimens investigated. Measured contact pressure distributions are compared to those determined using analytical and computer bases numerical techniques

Atmospheric predictability of the martian atmosphere: from low-dimensional dynamics to operational forecasting?

Not available

Mission F, LM descent/phasing summary document

Lunar module descent/phasing summary for mission

Towards a generalized theory of low-frequency sound source localization

Low-frequency sound source localization generates considerable amount of disagreement between audio/acoustics researchers, with some arguing that below a certain frequency humans cannot localize a source with others insisting that in certain cases localization is possible, even down to the lowest audible of frequencies. Nearly all previous work in this area depends on subjective evaluations to formulate theorems for low-frequency localization. This, of course, opens the argument of data reliability, a critical factor that may go some way to explain the reported ambiguities with regard to low-frequency localization. The resulting proposal stipulates that low-frequency source localization is highly dependent on room dimensions, source/listener location and absorptive properties. In some cases, a source can be accurately localized down to the lowest audible of frequencies, while in other situations it cannot. This is relevant as the standard procedure in live sound reinforcement, cinema sound and home-theater surround sound is to have a single mono channel for the low-frequency content, based on the assumption that human’s cannot determine direction in this band. This work takes the first steps towards showing that this may not be a universally valid simplification and that certain sound reproduction systems may actually benefit from directional low-frequency content

A theory of linear estimation

Theory of linear estimation and applicability to problems of smoothing, filtering, extrapolation, and nonlinear estimatio