84,200 research outputs found
Welding of high chromium steels
A brief description is given of different groups of high chromium steels (rustless iron and stainless steels) according to their composition and more generally accepted names. The welding procedure for a given group will be much the same regardless of the slight variations in chemical composition which may exist within a certain group. Information is given for the tensile properties (yield point and ultimate strength) of metal sheets and welds before and after annealing on coupons one and one-half inches wide. Since welds in rustless iron containing 16 to 18 percent chromium and 7 to 12 percent nickel show the best combination of strength and ductility in the 'as welded' or annealed condition, it is considered the best alloy to use for welded construction
Instrument accurately measures small temperature changes on test surface
Calorimeter apparatus accurately measures very small temperature rises on a test surface subjected to aerodynamic heating. A continuous thin sheet of a sensing material is attached to a base support plate through which a series of holes of known diameter have been drilled for attaching thermocouples to the material
Robust Bayesian inference via coarsening
The standard approach to Bayesian inference is based on the assumption that
the distribution of the data belongs to the chosen model class. However, even a
small violation of this assumption can have a large impact on the outcome of a
Bayesian procedure. We introduce a simple, coherent approach to Bayesian
inference that improves robustness to perturbations from the model: rather than
condition on the data exactly, one conditions on a neighborhood of the
empirical distribution. When using neighborhoods based on relative entropy
estimates, the resulting "coarsened" posterior can be approximated by simply
tempering the likelihood---that is, by raising it to a fractional power---thus,
inference is often easily implemented with standard methods, and one can even
obtain analytical solutions when using conjugate priors. Some theoretical
properties are derived, and we illustrate the approach with real and simulated
data, using mixture models, autoregressive models of unknown order, and
variable selection in linear regression
Heat sensing instrument Patent
Heat sensing instrument, using thermocouple junction connected under heavy conducting materia
The design and development of a solar tracking unit
The solar tracking unit was developed to support the Laser Heterodyne Spectrometer (LHS) airborne instrument, but has application to a general class of airborne solar occultation research instruments. The unit consists of a mirror mounted on two gimbals, one of which is hollow. The mirror reflects a 7.6 cm (3.0 in.) diameter beam of sunlight through the hollow gimbal into the research instrument optical axis. A portion of the reflected sunlight is directed into a tracking telescope which uses a four quadrant silicon detector to produce the servo error signals. The colinearity of the tracker output beam and the research instrument optical axis is maintained to better than + or - 1 arc-minute. The unit is microcomputer controlled and is capable of stand alone operation, including automatic Sun acquisition or operation under the control of the research instrument
Cyclotron resonance propulsion system semiannual report no. 1
Cyclotron resonance plasma accelerator for space propulsion application
Silicon halide-alkali metal flames as a source of solar grade silicon
The feasibility of using alkali metal-silicon halide diffusion flames to produce solar-grade silicon in large quantities and at low cost is demonstrated. Prior work shows that these flames are stable and that relatively high purity silicon can be produced using Na + SiCl4 flames. Silicon of similar purity is obtained from Na + SiF4 flames although yields are lower and product separation and collection are less thermochemically favored. Continuous separation of silicon from the byproduct alkali salt was demonstrated in a heated graphite reactor. The process was scaled up to reduce heat losses and to produce larger samples of silicon. Reagent delivery systems, scaled by a factor of 25, were built and operated at a production rate of 0.5 kg Si/h. Very rapid reactor heating rates are observed with wall temperatures reaching greater than 2000 K. Heat release parameters were measured using a cooled stainless steel reactor tube. A new reactor was designed
Computer simulation of plasma and N-body problems
The following FORTRAN language computer codes are presented: (1) efficient two- and three-dimensional central force potential solvers; (2) a three-dimensional simulator of an isolated galaxy which incorporates the potential solver; (3) a two-dimensional particle-in-cell simulator of the Jeans instability in an infinite self-gravitating compressible gas; and (4) a two-dimensional particle-in-cell simulator of a rotating self-gravitating compressible gaseous system of which rectangular coordinate and superior polar coordinate versions were written
Efficient planetary parking orbits with examples for Mars
Planetary parking orbits with examples for Mar
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