Isotropic thin-walled pressure vessel experiment

The objectives are: (1) to investigate the stress and strain distributions on the surface of a thin walled cylinder subject to internal pressure and/or axial load; and (2) to relate stress and strain distributions to material properties and cylinder geometry. The experiment, supplies, and procedure are presented

The role of fracture mechanics in the design of fuel tanks in space vehicles

With special reference to design of fuel tanks in space vehicles, the principles of fracture mechanics are reviewed. An approximate but extremely simple relationship is derived among the operating stress level, the length of crack, and the number of cycles of failure. Any one of the variables can be computed approximately from the knowledge of the other two, if the loading schedule (mission of the tank) is not greatly altered. Two sample examples illustrating the procedures of determining the allowable safe operating stress corresponding to a set of assumed loading schedule are included. The selection of sample examples is limited by the relatively meager available data on the candidate material for various stress ratios in the cycling

Third Conference on Artificial Intelligence for Space Applications, part 2

Topics relative to the application of artificial intelligence to space operations are discussed. New technologies for space station automation, design data capture, computer vision, neural nets, automatic programming, and real time applications are discussed

Thermochemical stability of low-iron, manganese-enriched olivine in astrophysical environments

Low-iron, manganese-enriched (LIME) olivine grains are found in cometary samples returned by the Stardust mission from comet 81P/Wild 2. Similar grains are found in primitive meteoritic clasts and unequilibrated meteorite matrix. LIME olivine is thermodynamically stable in a vapor of solar composition at high temperature at total pressures of a millibar to a microbar, but enrichment of solar composition vapor in a dust of chondritic composition causes the FeO/MnO ratio of olivine to increase. The compositions of LIME olivines in primitive materials indicate oxygen fugacities close to those of a very reducing vapor of solar composition. The compositional zoning of LIME olivines in amoeboid olivine aggregates is consistent with equilibration with nebular vapor in the stability field of olivine, without re-equilibration at lower temperatures. A similar history is likely for LIME olivines found in comet samples and in interplanetary dust particles. LIME olivine is not likely to persist in nebular conditions in which silicate liquids are stable

Fourth Conference on Artificial Intelligence for Space Applications

Proceedings of a conference held in Huntsville, Alabama, on November 15-16, 1988. The Fourth Conference on Artificial Intelligence for Space Applications brings together diverse technical and scientific work in order to help those who employ AI methods in space applications to identify common goals and to address issues of general interest in the AI community. Topics include the following: space applications of expert systems in fault diagnostics, in telemetry monitoring and data collection, in design and systems integration; and in planning and scheduling; knowledge representation, capture, verification, and management; robotics and vision; adaptive learning; and automatic programming

Condensation of Rocky Material in Astrophysical Environments

Volatility-dependent fractionation of the rock-forming elements at high temperatures is an early, widespread process during formation of the earliest solids in protoplanetary disks. Equilibrium condensation calculations allow prediction of the identities and compositions of mineral and liquid phases coexisting with gas under presumed bulk chemical, pressure and temperature conditions. A graphical survey of such results is presented for systems of solar and non-solar bulk composition. Chemical equilibrium was approached to varying degrees in the local regions where meteoritic chondrules, Ca-Al-rich inclusions, matrix and other components formed. Early, repeated vapor-solid cycling and homogenization, followed by hierarchical accretion in dust-rich regions, is hypothesized for meteoritic inclusions. Disequilibrium chemical effects appear to have been common at all temperatures, but increasingly so in less refractory meteoritic components. Work is needed to better model high-temperature solid solutions, indicators of these processes.Comment: 43 pages, 4 color plates, 2 figure

Condensation Calculations in Planetary Science and Cosmochemistry

Cool a piece of the Sun to 1000 K at one millibar pressure to yield a mineral assemblage consistent with those found in the most primitive meteorites. This is an equilibrium or fractional condensation experiment simulated by calculations using equations of state for hundreds of gaseous molecules, condensed mineral solids, and silicate liquids, the products of a century of experimental measurements and theoretical studies. Such calculations have revolutionized our understanding of the chemistry of the cosmos. The mid-20th Century realization that meteorites are fossil records of the early Solar System made chemistry central to understanding planetary origins. Thus "condensation", the distribution of elements and isotopes between vapor and condensed solids and/or liquids at or approaching chemical equilibrium, deeply informs discussion of how meteor/comet compositions bear on planets. Condensation calculations have been applied to disks around young stars, to the mineral "rain" of mineral grains expected to form in cool dwarf star atmospheres, to the expanding envelopes of giant stars, to the vapor plumes that form in planetary impacts, and to the chemically and isotopically distinct "shells" computed and observed to exist in supernovae. As with all sophisticated calculations, there are inherent caveats, subtleties, and computational difficulties. Local chemistry has yet to be consistently integrated into dynamical astrophysical simulations so that effects like the blocking of radiation by grains, absorption and reemission of light by grains, and buffering of heat by grain evaporation/condensation feed back into the physics at each node of a gridded calculation over time. A deeper integration of thermochemistry with physical models makes the prospect of a general protoplanetary disk model as hopeful now as a general circulation model for global climate was in the early 1970's.Comment: Review for Oxford Encyclopedi

The effect of font type on sight word reading performance of 4th and 5th grade students with reading disabilities

Reading interventions are a crucial component to combat barriers associated with reading difficulties. Within the education realm, nearly 50% of students who receive special education supports have a Specific Learning Disability (Gargiulo, 2006). As a result, the development and implementation of effective and targeted interventions is critical. Christian Boer developed a font called Dyslexie to help remediate reading difficulties of individuals with Dyslexia (Boer, 2011). However, studies by de Leeuw (2010) and Pjipker (2013) provide inconsistent supportive evidence, regarding the effectiveness of Dyslexie. The current study sought to examine the effectiveness of Dyslexie as compared to Arial on sight word recognition tasks. A total of 36 fourth and fifth grade students with a Specific Learning Disability read two real word lists and one pseudoword lists in either font. Results do not suggest a significant difference between either font on sight word recognition tasks. Results, future directions, and implications for School Psychologists are discussed