Optical bistability for two-level atoms in a standing-wave cavity

Observations of optical bistability are reported for a system composed of multiple atomic beams passing through a high-finesse optical cavity. Both the transmitted power and the intracavity fluorescent intensity have been recorded as functions of incident laser power for zero cavity and atomic detunings. A quantitative study has been made of the evolution of the steady-state switching intensities from well below the critical onset of bistability to well above this point. The results show reasonable agreement with a Gaussian-beam theory of optical bistability, but systematic departures are noted

The gradational history of southern Ismenius Lacus

Two epochs of accelerated gradation affected the geomorphic evolution of southern Ismenius Lacus. These periods of enhanced gradational activity were likely related to periods of more clement climate induced by release of either recycled exogenic or juvenile endogenic atmospheric volatiles. Variations in the intensity and duration of gradation during the second epoch are indicated by the variability in the timing of cessation and degree of air fall deposit removal across the study area. Overall intensity of gradation decreased through successive epochs based on: (1) the decreasing diameter at which cumulative statistics from the respective surfaces cease to follow the expected production function; and (2) the decrease in size/increase in density of preserved valley networks incised into surfaces of differing age. A comparable decrease in valley density with time has been noted in the Isidis region

Thin film temperature sensor

Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed

Characteristics of ejecta and alluvial deposits at Meteor Crater, Arizona and Odessa Craters, Texas: Results from ground penetrating radar

Previous ground penetrating radar (GRP) studies around 50,000 year old Meteor Crater revealed the potential for rapid, inexpensive, and non-destructive sub-surface investigations for deep reflectors (generally greater than 10 m). New GRP results are summarized focusing the shallow sub-surfaces (1-2 m) around Meteor Crater and the main crater at Odessa. The following subject areas are covered: (1) the thickness, distribution, and nature of the contact between surrounding alluvial deposits and distal ejecta; and (2) stratigraphic relationships between both the ejecta and alluvium derived from both pre and post crater drainages. These results support previous conclusions indicating limited vertical lowering (less than 1 m) of the distal ejecta at Meteor Crater and allow initial assessment of the gradational state if the Odessa craters

Circular 35

Revised April 1991 by Grant E.M. Matheke, Patricia J. Wagner, and Patricia S. Holloway; Reprinted by Cooperative Extension Service, University of Alaska Fairbanks, and U.S.D.A. Cooperating. Publication 300C-00235A technique for growing high-yielding, everbearing strawberries with clear polyethylene (plastic) mulch and row covers has been developed at the Agricultural and Forestry Experiment Station at Fairbanks. This technique eliminates the long delay from planting to fruiting that occurs with other culture systems and it has created an interest in commercial production and an increased home-garden effort in Alaska. The production system involves planting nursery plants each season as early as possible through clear polyethylene mulch, using row covers for the early part o f the season. Using this technique, harvest begins about July 15 and extends until freeze-up, com pared to a production season from about July 10 to July 28 for hardy types o f strawberries such as Toklat or Pioneer. This system produces clean fruit, easy to pick and relatively free from fruit rot. The harvest season can be extended in the fall by again using the row covers for frost protection

Turbine Blade Temperature Measurements Using Thin Film Temperature Sensors

The development of thin film temperature sensors is discussed. The technology for sputtering 2 micron thin film platinum versus platinum 10 percent rhodium thermocouples on alumina forming coatings was improved and extended to applications on actual turbine blades. Good adherence was found to depend upon achieving a proper morphology of the alumina surface. Problems of adapting fabrication procedures to turbine blades were uncovered, and improvements were recommended. Testing at 1250 K at one atmosphere pressure was then extended to a higher Mach No. (0.5) in combustor flow for 60 hours and 71 thermal cycles. The mean time to failure was 47 hours accumulated during 1 hour exposures in the combustor. Calibration drift was about 0.1 percent per hour, attributable to oxidation of the rhodium in the thin films. An increase in film thickness and application of a protective overcoat are recommended to reduce drift in actual engine testing

Dispersion strenghthening of metals Progress report, Sep. 1965 - Feb. 1966

Apparatus constructed for controlled oxidation of iron-beryllium alloy powder

Significance of solutions of the inverse Biot-Savart problem in thick superconductors

The evaluation of current distributions in thick superconductors from field profiles near the sample surface is investigated theoretically. A simple model of a cylindrical sample, in which only circular currents are flowing, reduces the inversion to a linear least squares problem, which is analyzed by singular value decomposition. Without additional assumptions about the current distribution (e.g. constant current over the sample thickness), the condition of the problem is very bad, leading to unrealistic results. However, any additional assumption strongly influences the solution and thus renders the solutions again questionable. These difficulties are unfortunately inherent to the inverse Biot-Savart problem in thick superconductors and cannot be avoided by any models or algorithms