Abstract: The disclosed dual mode direct current power supply comprises an AC transformer, a pair of DC output terminals, and first and second rectifier-filter circuits connected in parallel between the transformer and such terminals; the first circuit comprising first rectifiers for producing first rectified pulses, a first capacitor adapted to be charged to the peak voltage of such pulses, and an electronic voltage regulator including a series transistor; the second rectifier-filter circuit including second rectifiers for producing second rectified pulses, a choke input filter including an inductance and a second capacitor adapted to be charged through the inductance to the average voltage of the second pulses, and a series diode; the regulator causing the transistor to be nonconductive at high DC output voltage and then conductive increasingly in response to decreasing output voltage whereby the first rectifier-filter circuit supplies an increasing share of the load current.

Abstract: A framework for a building or other hollow object utilizing a plurality of basic building elements which are interconnected together in which each of the elements is constructed of a sheet of bendable resilient material which has a substantially flat permanent set, and each sheet is provided with three pairs of equally spaced apertures for interconnecting the building elements, each pair of connection apertures defining an axis which extends between the connection apertures, and the axes between the three pairs of connecting apertures intersecting at angles of 60.degree. to form an equilateral triangle centrally of the sheet, the sheets being interconnected by pins extending through apertures to form a hollow body. Four embodiments are disclosed, one in which legs extend from the central triangle portion, and two embodiments in which a six-sided sheet forms the basic building element.

Abstract: A stand is adapted to support a musical instrument, such as a guitar, in an upright manner and is adapted to be assembled or disassembled in a rapid and convenient manner. The stand includes a pair of spaced-apart upright L-shaped members inclined toward one another. The members include forwardly projecting spaced-apart foot portions for supporting the bottom portion of the musical instrument. Strut members extend between the L-shaped members to help rigidify them. A support device releasably attached to the upper portion of at least one of the L-shaped members supports the upper portion of the musical instrument. The support device is also adapted to support sheet music, and a foot rest is provided and swings between a horizontal use position for receiving and supporting the foot of the user during the playing of the musical instrument and a generally vertical position behind and out of the way of the musical instrument when it is resting on the stand.

Abstract: A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

Abstract: A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

Abstract: 1. The method of operating a water-cooled neutronic reactor having a graphite moderator which comprises flowing a gaseous mixture of carbon dioxide and helium, in which the helium comprises 40-60 volume percent of the mixture, in contact with the graphite moderator.

Abstract: 1.