Apparatus for study of plasmas at elevated temperatures

Microwave discharge plasmas take place within heated zone. Changes in weight of specimens in plasma as well as temperature of sample and plasma can be obtained, facilitating determinations of reaction rates and recombination coefficients

Semipermanent sealing of leaks in high vacuum systems

Silicone-rubber adhesive is applied externally to seal hair-line cracks in sections of high vacuum system while system is partially evacuated. No pretreatment of surface is required since adhesive will be drawn into crack while diffusion or ion pump is off

The effect of heat treatment and test parameters on the aqueous stress corrosion cracking of D6AC steel

The crack growth behavior of D6AC steel as a function of stress intensity, stress and corrosion history and test technique, under sustained load in natural seawater, 3.3 percent NaCl solution, distilled water, and high humidity air was investigated. Reported investigations of D6AC were considered with emphasis on thermal treatment, specimen configuration, fracture toughness, crack-growth rates, initiation period, threshold, and the extension of corrosion fatigue data to sustained load conditions. Stress history effects were found to be most important in that they controlled incubation period, initial crack growth rates, and apparent threshold

Introductory assessment of orbiting reflections for terrestrial power generation

The use of orbiting mirrors for providing energy to ground conversion stations to produce electrical power is shown to be a viable, cost effective and environmentally sound alternative to satellite solar power stations and conventional power sources. This is accomplished with the use of very light weight metal coated polymeric films as mirrors which, after deployment at 800 km, are placed in operational orbit and controlled by solar radiation pressure. Relations are developed showing the influence of a number of parameters (mirror altitude, orbit inclination, period, mirror size and number, and atmospheric effects) on the reflected insolation that may be received by a ground spot as a function of location. Some attractive alternative uses of the reflection are briefly discussed as a beneficial adjuncts to the system

Electrical conductivity cell and method for fabricating the same

A flask having a threaded neck and a cap adapted for threaded engagement on the neck are used. A laminated disc between the cap and the neck forms a gas tight seal and the cap has a central opening that exposes a medial region of the disc. Piercing the disc through the opening are two electrodes, the inner ends of which contact the sample within the flask and the outer ends of which can be connected to test equipment. Cylindric glass tubes are fitted over the external portion of the electrodes to provide physical support and silicone rubber or a similar material serves to retain the glass cylinders in place and form a gas tight seal between the cylinders and the electrodes. Shrinkable tubing is shrunk over the glass tubes to afford further mechanical support and sealing. A final relatively large diameter shrinkable tube is shrunk over both electrodes and their associated glass cylinders. The support and sealing means for the electrodes is confined to a limited portion of the medial region of the disc so that the remainder of such region can be punctured by a hollow needle to introduce a test sample within the flask

Space Resources and Space Settlements

The technical papers from the five tasks groups that took part in the 1977 Ames Summer Study on Space Settlements and Industrialization Using Nonterrestrial Materials are presented. The papers are presented under the following general topics: (1) research needs for regenerative life-support systems; (2) habitat design; (3) dynamics and design of electromagnetic mass drivers; (4) asteroids as resources for space manufacturing; and (5) processing of nonterrestrial materials

Advanced Automation for Space Missions

The feasibility of using machine intelligence, including automation and robotics, in future space missions was studied

Turbulence Time Series Data Hole Filling using Karhunen-Loeve and ARIMA methods

Measurements of optical turbulence time series data using unattended instruments over long time intervals inevitably lead to data drop-outs or degraded signals. We present a comparison of methods using both Principal Component Analysis, which is also known as the Karhunen--Loeve decomposition, and ARIMA that seek to correct for these event-induced and mechanically-induced signal drop-outs and degradations. We report on the quality of the correction by examining the Intrinsic Mode Functions generated by Empirical Mode Decomposition. The data studied are optical turbulence parameter time series from a commercial long path length optical anemometer/scintillometer, measured over several hundred metres in outdoor environments.Comment: 8 pages, 9 figures, submitted to ICOLAD 2007, City University, London, U

Properties of the H-alpha-emitting Circumstellar Regions of Be Stars

Long-baseline interferometric observations obtained with the Navy Prototype Optical Interferometer of the H-alpha-emitting envelopes of the Be stars eta Tauri and beta Canis Minoris are presented. For compatibility with the previously published interferometric results in the literature of other Be stars, circularly symmetric and elliptical Gaussian models were fitted to the calibrated H-alpha observations. The models are sufficient in characterizing the angular distribution of the H-alpha-emitting circumstellar material associated with these Be stars. To study the correlations between the various model parameters and the stellar properties, the model parameters for eta Tau and beta CMi were combined with data for other Be stars from the literature. After accounting for the different distances to the sources and stellar continuum flux levels, it was possible to study the relationship between the net H-alpha emission and the physical extent of the H-alpha-emitting circumstellar region. A clear dependence of the net H-alpha emission on the linear size of the emitting region is demonstrated and these results are consistent with an optically thick line emission that is directly proportional to the effective area of the emitting disk. Within the small sample of stars considered in this analysis, no clear dependence on the spectral type or stellar rotation is found, although the results do suggest that hotter stars might have more extended H-alpha-emitting regions.Comment: 24 pages, 16 figures, accepted for publication in Ap

Plant use of the Maasai of Sekenani Valley, Maasai Mara, Kenya

Traditional plant use is of tremendous importance in many societies, including most rural African communities. This knowledge is however, rapidly dwindling due to changes towards a more Western lifestyle, and the influence of modern tourism. In case of the Sekenani Maasai, the recent change from a nomadic to a more sedentary lifestyle has not, thus far lead to a dramatic loss of traditional plant knowledge, when compared to other Maasai communities. However, in Sekenani, plants are used much less frequently for manufacturing tools, and for veterinary purposes, than in more remote areas. While the knowledge is still present, overgrazing and over-exploitation of plant resources have already led to a decline of the plant material available. This paper examines the plant use of the Maasai in the Sekenani Valley, North of the Masaai Mara National Reserve. The Maasai pastoralists of Kenya and Tanzania use a large part of the plants in their environment for many uses in daily life. The plant use and knowledge of the Sekenani Maasai is of particular interest, as their clan, the "Il-Purko", was moved from Central Kenya to this region by the British Colonial Administration in 1904. The results of this study indicate that despite their relocation 100 years ago, the local population has an extensive knowledge of the plants in their surroundings, and they ascribe uses to a large percentage of the plants found. One-hundred-fifty-five plant species were collected, identified and their Maa names and traditional uses recorded. Although fifty-one species were reported as of "no use", only eighteen of these had no Maasai name. Thirty-three were recognized by a distinctive Maa name. Thirty-nine species had a medicinal use, and 30 species served as fodder for livestock. Six species could not be identified. Of these plants five were addressed by the Maasai with distinct names. This exemplifies the Sekenani Maasai's in-depth knowledge of the plant resources. Traditionally, the Maasai attribute most illnesses to the effect of pollutants that block or inhibit digestion. These pollutants can include "polluted" food, contact with sick people and witchcraft. In most cases the treatment of illness involves herbal purgatives to cleanse the patient. There are alsofrequent indications of plant use for common problems like wounds, parasites, body aches and burns