Study of Umbrella-Type Erectable Paraboloidal Solar Concentrators for Generation of Spacecraft Auxiliary Power

An investigation was made of some aspects of erectable umbrella-type paraboloidal solar-energy concentrators for use in spacecraft auxiliary power systems. An analysis is presented for the design of concentrators employing radial ribs and membrane-type coverings. The rib stiffness necessary to give a desired parabolic curvature upon erection is determined. Rib contour measurements were made in an upright and inverted position on an experimental 10-foot-diameter concentrator giving a focal length of 30.78 inches and 30.6 inches, respectively, as compared with a design focal length of 30 inches. Calorimetric tests employing spherical heat receivers showed a maximum geometrical concentrator efficiency of 75.3 percent with a concentration ratio of 92.2 at a focal length of approximately 30.5 inches. Within the scope of this investigation, it was found that, as the concentrator size increases, the weight per unit projected area increases, time to damp to one-half amplitude increases, and the natural frequency decreases. Umbrella-type solar concentrators appear to be feasible for power conversion systems using low concentration ratios; however, for large concentrators the time required to damp out disturbances may be a problem

Westward bottom currents along the margin of the South Shetland Island Arc

Existing information is synthesized and new data presented to describe the flow of near-bottom water from the Weddell Sea into the Scotia Sea and westward through Drake Passage along the continental slope. The water characteristics and currents along the northern margins of the South Sandwich Island Arc are examined. Long-term current measurements in the bottom waters at locations over the outer shelf and slope and along the continental rise show persistent flow from Atlantic to Pacific along isobaths at speeds of 10–20 cm s−1. Three sources for the waters in these currents are identified and discussed. At the deepest levels, Weddell Sea Deep Water enters the Scotia Sea near 40°W through a depression in the South Scotia Arc and then flows westward, constrained by the bottom topography. This cold, fresh, oxygenated bottom water then flows west to enter Drake Passage via a gap in the Shackleton Fracture Zone at the base of the continental slope northwest of Elephant Island. Mid-depth water may flow from the Weddell Sea to the Scotia Sea through the Powell Basin (sill depth approximately 2000 m) located west of South Orkney Island near 48°W. The westward flowing waters along the shelf and upper continental slope, which are denser than those immediately offshore, may be a continuation of the Polar Slope Current from the Weddell Sea or may be derived principally by convection from the shelves of the South Sandwich Island Arc. A vertical section north of Elephant Island shows downslope convection off the shelf, analogous to the observed at many locations around Antartica

The nitrogen isotopic separation factors of various organic amines on amberlite IR-120 cation exchange resin

Ion-exchange displacement chromatography was used to measure the nitrogen isotopic separation factors of ten organic amines and ammonium hydroxide. A column of Amber lite IR-120 H+ -form resin was used, and the aqueous amine solutions were approximately 0. 125N. The separation factors of the compounds investigated are: ammonium hydroxide, 1. 0254; methylamine, 1. 0223; ethylamine, 1. 0218; n-propylamine, 1. 0199; iso-propylamine, 1. 0197; n- butylamine, 1. 0183; dimethylamine, 1. 01 74; diethylamine, 1. 01 72; dipropylamine, 1. 0159; trimethylamine, 1. 0130; and triethylamine, 1. 0117

The kinematic and thermohaline zonation of the Antarctic Circumpolar Current at Drake Passage

The waters of the Antarctic Circumpolar Current at Drake Passage show mesoscale horizontal zonation into four water mass regimes horizontally separated by three fronts. Vertical profiles of T, S and O2 on opposite sides of each front are described and compared. Although the surface waters are significantly different across fronts, the vertical profiles from the same side of a specific front are remarkably uniform from year to year and from cruise to cruise...

Some features of the deep water in the Gulf of Mexico

In the central Gulf of Mexico, 52 stations having depths greater than 1500 m were occupied within a seven-week period. The data for waters below sill depth (2000 m) show that the ranges of potential temperature and salinity are very limited, although weak vertical gradients indicate a slight positive stability...

The Physics of the Antarctic Circumpolar Current

A region of transition of surface water characteristics from subantarctic to Antarctic and an associated eastward flowing Antarctic Circumpolar Current (ACC) have long been recognized to exist as a band around Antarctica. In this review we summarize the most important observational and theoretical findings of the past decade regarding the ACC, identify gaps in our knowledge, and recommend studies to address these. The nature of the meridional zonation of the ACC is only now being revealed. The ACC seems to exist as multiple narrow jets imbedded in, or associated with, density fronts (the Subantarctic and Polar fronts) which appear to be circumpolar in extent. These fronts meander, and current rings form from them; lateral frontal shifts of as much as 100km in 10 days have been observed. The volume transport of the ACC has been estimated many times with disparate results

Repeated nutrient, oxygen, and density sections through the Loop Current

Based on observations made in May, 1972, the nutrient and dissolved-oxygen concentrations in the offshore waters of the eastern Gulf of Mexico are described and related to the Loop Current and anticyclonic current rings, which are the principal circulation features of this region. The characteristic relationships of oxygen and nutrients to density parameters are presented..

The International Oceanographic Tables

Tables I and II of the series International Oceanographic Tables have been in print for longer than a year. The oceanographic community is indebted to members of the Joint Panel on Oceanographic Tables and Standards (JPOTS), particularly to its chairman, Roland A. Cox, and to others, for the work represented by these tables

A characterization of the Gulf of Mexico waters in winter

The results of a rapid survey of the Gulf of Mexico in the winter of 1962 are presented. Variations in the characteristics of the water in several core layers are described. Circulation has been examined on the basis of dynamic computations and G.E.K. measurements. In the eastern Gulf, water enters through Yucatan Strait and leaves through Florida Strait, flowing in an anticyclonic loop that extends well into the Gulf...

The importance of the Scotia Sea on the outflow of Weddell Sea Deep Water

Weddell Sea Deep Water influences the thermohaline circulation of the world ocean directly as a component of the deep western boundary current in the South Atlantic Ocean and indirectly by cooling and freshening Circumpolar Deep Water. Because it is filled with recently ventilated Weddell Sea Deep Water, the Scotia Sea is important to both influences. The main component of the abyssal waters renewing most of the world oceans via deep boundary currents is the Circumpolar Deep Water of the Antarctic Circumpolar Current. Weddell Sea Deep Water is recognized as the main source of cold, fresh waters to Circumpolar Deep Water, and we show that Weddell Sea Deep Water is incorporated into the Antarctic Circumpolar Current within the Scotia Sea. As a result of this ventilation, the Scotia Sea provides an effective link between the deep waters of the Weddell Sea and the rest of the world abyssal ocean. Some of the Weddell Sea Deep Water filling the Scotia Sea leaves as a westward flow via the southern Drake Passage. Weddell Sea Deep Water also enters the Georgia Basin directly from the Scotia Sea and flows beneath the Antarctic Circumpolar Current to contribute to the deep western boundary current of the Argentine Basin. In most previous studies, a deep spreading route from the Weddell Sea over the South Sandwich Trench east of the Scotia Sea had been considered the only source of Weddell Sea Deep Water for this deep western boundary current