LSS 2018: A double-lined spectroscopic binary central star with an extremely large reflection effect

LSS 2018, the central star of the planetry nebulae DS1, was found to be a double-lined spectroscopic binary with a period of 8.571 hours. Light variations with the same period were observed in U, B, and V; in the wavelength regions defined by the two IUE cameras; and in the strength of the CIII 4647 emission line. The light variations can be accurately predicted by a simple reflection effect, and an analysis of the light curves yields the angular diameter and effective temperature of the primary, the radii of the two stars in terms of their separation, and the inclination of the system. Analysis of the radial velocities then yields the masses of the two stars, their separation, the distance of the system, the absolute magnitude of the primary, and the size of the nebula

The LSS 4300: A hot counterpart of Upsilon Sgr and KS Per?

A number of observations indicate that the star LSS 4300 is a high temperature analog of the hydrogen-deficient binaries upsilon Sgr and KS Per. A preliminary model-atmosphere analysis based on high-dispersion spectra obtained at Kitt Peak and Cerro Tololo yields T(eff) = 14,400 K, log(g) = 1.4, n(H)/n(He) = 0.003, and n(N)/n(C) = 20 (the corresponding values for upsilon Sgr are T(eff) = 10,000 K, log(g) = 1, n(H)/n(He) = 0.0005, and n(N)/n(C) = 20). The optical emission-line spectrum of LSS 4300 is nearly identical to that of upsilon Sgr, including strong, broad H alpha, FeII and Ca II emission. The ultraviolet spectrum of LSS 4300 was observed with IUE, and can be attributed almost entirely to the visible star. The JHKL photometry of LSS 4300 obtained at Cerro Tololo reveals an infrared excess nearly identical to that of upsilon Sgr. It is suggested that LSS 4300, like upsilon Sgr and KS Per, is a close binary system consisting of a helium supergiant of about one solar mass, and a secondary which is overluminous for its mass due to the accretion of matter from the primary, which is undergoing its second mass exchange

Effective temperatures and luminosities of very hot o-type subdwarfs

Twelve very hot O-type subdwarfs were observed with the IUE-satellite in the low dispersion mode. Temperatures were derived from the slopes of the UV continua and distances were estimated from the color excesses. Most of them are hotter than 60,000 K, i.e., they are the hottest known subdwarfs. From their spectral appearance and location in a H.R.-diagram they form a rather inhomogeneous group. Three of them turned out to be central stars or nearly central stars, and four are definitely near the white dwarf stage. The surface helium to hydrogen ratio varies from about normal to the extreme case. Most of them appear to be post EHB objectives of 0.5 solar mass with a helium burning shell as their energy source, and their peculiar helium-to-hydrogen ratios are most likely the result of diffusion and convective mixing in surface layers

Conceptual design of a noncontacting power transfer device for the ASPS Vernier system

The conceptual of electrical power transfer across a magnetically controlled gap as discussed for several years. The design represents the culmination of the first serious attempt to design a very low force, noncontracting power transfer mechanism. The electromagnetic device advanced herein is an ironless, translatable secondary transformer in which one of the two coils is fixed to the entire magnetic core. The second coil is free to move within the core over the full range of motions required. The specific application considered for this design was the Vernier subsystem of the Annular Suspension and Pointing System (ASPS). The development of and rationale for the electromagnetics design is presented. Similar documentation is provided for the Electronics Design. The Appendices detail the results of small scale model tests, disturbance force calculations, the baseline transformer fabrication drawings, the AVS Converter Parts List, and model schematic diagrams

Abundance analysis of cool extreme helium star: LSS 3378

Abundance analysis of the cool extreme helium (EHe) star LSS 3378 is presented. The abundance analysis is done using LTE line formation and LTE model atmospheres constructed for EHe stars. The atmosphere of LSS 3378 shows evidence of H-burning, He-burning, and s-process nucleosynthesis. The derived abundances of iron-peak and alpha-elements indicate absence of selective fractionation or any other processes that can distort chemical composition of these elements. Hence, the Fe abundance (log epsilon(Fe) = 6.1) is adopted as an initial metallicity indicator. The measured abundances of LSS 3378 are compared with those of R Coronae Borealis (RCB) stars and with rest of the EHe stars as a group.Comment: 7 pages, 4 figures, 3 tables, MNRAS format, accepted for publication in MNRA

Wood wasp inspired space and earth drill

In this chapter, we explain why the low gravity encountered on Mars or on the Moon and the low mass of the probes, landers and rovers that carry drilling devices limit classical drilling techniques. Novel boring solutions optimised in mass and power consumption are thus needed for space applications. Biologists have identified the wood wasp, an insect that is capable of "drilling" into wood to lay its eggs. A low mass and low power system, like an insect, capable of drilling into wood is of the highest interest for planetary drilling and terrestrial drilling alike. The general working principle of the wood wasp drill ("dual reciprocating drilling") will be exposed and the potential benefits of imitating the wood wasp for planetary drilling will be highlighted. Since the nature of wood is highly fibrous but the nature of extraterrestrial and terrestrial soils are not, it is necessary to adapt the wood wasp ovipositor to our target soils. A test bench to evaluate the influence of the different geometries and operational parameters was produced and is presented here. The dual reciprocating drilling experimental results obtained on this test bench are also highlighted. They should lead to a new and enhanced model and comprehension of dual-reciprocating-drilling

Shale problems and water-based drilling fluid optimisation in the Hassi Messaoud Algerian oil field

Drilling fluid formulation and properties play a fundamental role in drilling operations. Clay minerals behave initially as a beneficial rheological adjuvant in drilling muds. Nevertheless, the contamination of oil reservoirs by clay minerals present in the drilled geological formation (shales) may generate major problems during drilling as plug formation. In this context, our study deals with the optimisation of drilling conditions in the Hassi Messaoud Algerian field. The mineralogical heterogeneity of this field is first discussed. The rheological and filtration characteristics of water-based muds with different polymer and electrolyte concentrations are investigated. The physical and chemical changes of both drilled formation and drilling fluid during the drilling process are studied. Therefore, depending on the clay present in the geological formation, an optimised drilling fluid system using a new filtration procedure is proposed. A good correlation is found between filtration/rheological properties and inhibition

Premiminary tests on modified clays for electrolyte contaminated drilling fluids

The quality of a bentonite suspension declines in aggressive systems like brackish or saline pore water. An engineered clay (HYPER clay) was developed for sealing materials with enhanced resistance to aggressive conditions. The modified clay is produced by treating a sodium activated bentonite with a cellulose polymer following the HYPER clay process method. This study investigates the suitability of the modified clay for electrolyte contaminated drilling fluids. Drilling fluids become contaminated with saline pore water, e.g. pick up an electrolyte contamination, while drilling a formation at for example an estuary or near the coast. Preliminary laboratory tests were performed to study drilling fluid resistance to electrolytes. Therefore the drilling fluids were contaminated with sea water. Subsequently drilling fluid functionality was characterized by its filtration performance, thixotropic behavior, rheology (gel strength, yield point and viscosity) and bleeding behavior. Drilling fluid performance was analyzed at various electrolyte concentrations (7.6, 14 and 28 volume percentage sea water by total volume). Filter press tests (API, 13B-I) showed that the filtration performance improved significantly due to polymer treatment. Moreover, results showed that the rheology properties can be controlled using Xanthan Gum as an additiv

Test well exploration in the Myakka River Basin area, Florida

In recent years, difficulties encountered in obtaining ground-water supplies with acceptable chemical characteristics in the Myakka River basin area led to the implementation of a test drilling program. Under this program, well drilling and data collection were executed in such a manner that all water-producing zones of the local aquifers, together with the quality and quantity of the water available, were effectively identified. A step-drilling method was utilized which allowed the collection of formation cuttings, water samples, and water-level data, from isolated zones in the well as drilling proceeded. The step drilling procedure is described. The driller's logs, geophysical logs, and chemical quality of water tables are presented.(Document has 66 pages.