Causal Interfaces

The interaction of two binary variables, assumed to be empirical observations, has three degrees of freedom when expressed as a matrix of frequencies. Usually, the size of causal influence of one variable on the other is calculated as a single value, as increase in recovery rate for a medical treatment, for example. We examine what is lost in this simplification, and propose using two interface constants to represent positive and negative implications separately. Given certain assumptions about non-causal outcomes, the set of resulting epistemologies is a continuum. We derive a variety of particular measures and contrast them with the one-dimensional index.Comment: 20 pages, 3 figure

Stress Interference in Axisymmetric Torsion of a Transeversely Isotropic Body

An unbounded transversely isotropic body of revolution containing two spheroidal cavities is subjected to torsion about its axis of elastic symmetry, which coincides with its axis of revolution. At large' distances from the cavities the elastic field approaches the Saint-Venant solution for the torsion of a circular cylinder. The elasticity solution is obtained in series form and numerical results presented for the case of two spherical cavities. Of primary interest is the degree of stress interference between the. two perturbations, as a function of the spacing of the cavities and the values of the elastic constants.Air Force Office of Scientific Research Grant No. AFOSR 82-004

The development of a complementary expendable launch vehicle interface for an STS deployable payload

The development is described of an interface, the Titan Payload Adapter (TPA), between a Space Transportation System (STS) deployable payload and an expendable launch vehicle (ELV). Separate ascent and separation constraint systems allow a payload with integral trunnions to retain its originally designed, boost-phase load structure, yet also allow the expendable booster vehicle to separate from the payload via retro-rockets. Design requirements as well as development problems and their solutions are discussed

Foamed in place ceramic refractory insulating material Patent

Characteristics of foamed-in-place ceramic refractory insulating material and method of fabricatio

Noise limitations of multiplier phototubes in the radiation environment of space

The contributions of Cerenkov emission, luminescence, secondary electron emission, and bremsstrahlung to radiation-induced data current and noise of multiplier phototubes were analyzed quantitatively. Fluorescence and Cerenkov emission in the tube window are the major contributors and can quantitatively account for dark count levels observed in orbit. Radiation-induced noise can be minimized by shielding, tube selection, and mode of operation. Optical decoupling of windows and cathode (side-window tubes) leads to further reduction of radiation-induced dark counts, as does reducing the window thickness and effective cathode area, and selection of window/cathode combinations of low fluorescence efficiency. In trapped radiation-free regions of near-earth orbits and in free space, Cerenkov emission by relativistic particles contributes predominantly to the photoelectron yield per event. Operating multiplier phototubes in the photon (pulse) counting mode will discriminate against these large pulses and substantially reduce the dark count and noise to levels determined by fluorescence

Effects of simulated space radiation on selected optical materials

The effect of simulated Nimbus spacecraft orbital (1100 km, circular, and polar) radiation on wide bandpass glass filters, narrow bandpass thin film interference filters, and several fused silicas was determined by transmittance measurements over the 200 to 3400 nanom wavelength region. No changes were observed in the filters, which were shielded with fused silica during irradiation, after exposure to a 1-year equivalent orbital dose of electrons, nor in the fused silicas after the same electron exposure plus a 1-year equivalent dose of protons. Exposure to a 1/2-year equivalent dose of solar ultraviolet radiation caused a significant degradation in the transmittance of two ultraviolet-transmitting interference filters but had no effect on two colored glass filters that transmitted in the visible and near infrared regions. As a result of the ultraviolet exposure the fused silicas exhibited losses of several percent over the 200- to 300 nanom wavelength region