20,028 research outputs found
Microbiological aspects of sterilization development laboratories
Report deals with an investigation of vertical laminar flow clean rooms for use in spacecraft assembly. A reduction of particulate and microbial contamination occurs in the application
A brushless dc spin motor for momentum exchange altitude control
Brushless dc spin motor is designed to use Hall effect probes as means of revolving rotor position and controlling motor winding currents. This results in 3 to 1 reduction in watt-hours required for wheel acceleration, a 2 to 1 reduction in power to run wheel, and a 10 to 1 reduction in the electronics size and weight
The microbiological aspects of sterilization assembly development laboratories, EASL and SADL
Microbiological aspects of operations in two sterilization development laboratories for spacecraft assembl
2-Segal objects and algebras in spans
We define a category parameterizing Calabi-Yau algebra objects in an infinity category of spans. Using this category, we prove that there are equivalences of infinity categories relating, firstly: 2-Segal simplicial objects in C to algebra objects in Span(C); and secondly: 2-Segal cyclic objects in C to Calabi-Yau algebra objects in Span(C)
A method for determining an optimum shape of a class of thin shells of revolution
Optimum shape of convex thin shell of revolution with respect to volume, weight and length - mathematical functio
Using Satellites to Probe Extrasolar Planet Formation
Planetary satellites are an integral part of the heirarchy of planetary
systems. Here we make two predictions concerning their formation. First,
primordial satellites, which have an array of distinguishing characteristics,
form only around giant planets. If true, the size and duration of a planetary
system's protostellar nebula, as well as the location of its snow line, can be
constrained by knowing which of its planets possess primordial satellites and
which do not. Second, all satellites around terrestrial planets form by
impacts. If true, this greatly enhances the constraints that can be placed on
the history of terrestrial planets by their satellites' compositions, sizes,
and dynamics
Extreme 18O-enrichment in majorite constrains a crustal origin of transition zone diamonds
The fate of subducted oceanic lithosphere and its role in the planet-scale geochemical cycle is a key problem in solid Earth studies. Asthenospheric and transition zone minerals included in diamond have been interpreted as representing subducted oceanic crust based on inclusion REE patterns and strong 13C depletion of their host diamond (δ13C as low as -23 ‰). This view/explanation, however, has been challenged by alternative interpretations that variable carbon isotopic compositions either result from high temperature fractionation involving carbides, or reflect primordial, unhomogenised mantle reservoirs. Here, we present the first oxygen isotope analyses of inclusions in such ultradeep diamonds – majoritic garnets in diamond from Jagersfontein (South Africa). The oxygen isotope compositions provide unambiguous evidence for derivation of the inclusions from subducted crustal materials. The δ18OVSMOW values of the majorites range from +8.6 ‰ to +10.0 ‰, well outside that of ambient mantle (+5.5 ±0.4 ‰) and indicate that the protoliths were very heavily weathered at relatively low temperatures. When this information is combined with the broadly eclogitic composition of the majoritic garnets, a derivation from subducted sea-floor basalts is implied. Based on the association between the heavy oxygen and light carbon, the light carbon isotope composition cannot relate to deep mantle processes and is also ultimately derived from the crust
Determination of Mica Cell Parameters by X-Ray Powder Diffractometry — A Case Study
Possibilities and restrictions of least-square methods for mica cell refinement are briefly described. If diffractometric raw data are precise and accurate, and if geometrical errors are properly corrected, a cell refinement (determination of ao, bo, cO, β) can be carried out rapidly, but the reliability of obtained data has to be evaluated carefull
A preliminary quarantine analysis of a possible Mariner Venus 1972 mission
Spacecraft contamination preliminary quarantine analysis for possible 1972 Mariner Venus prob
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