Bare Ends Research Articles

A fast response thermocouple for temperature fluctuation measurements in sodium coolants

A special chromel/alumel thermocouple was fabricated whereby the bare ends of the wires were fixed about 1 mm apart. In a medium with a good electrical conductivity (e.g. liquid sodium) the junction of this thermocouple is replaced by the medium itself. Hence, a fast undelayed response is expected. Experimental data for this device compared with corresponding dynamical data for conventional thermocouples will be presented. Beside the fact that the mean temperatures of both elements are in good agreement it is shown that the open element exhibits a much faster time behaviour than conventional thermocouples.

New Paint-On Electrodes for Surface Electromyography

A NASA-developed paint-on electrode has been adapted for biomedical applications by the Research Triangle Institute. 10 g of silver flake are suspended in 10 g of Duco cement and 1 oz of acetone. This mixture may be stored indefinitely, with occasional addition of acetone for thinning. In electromyographic use, each electrode is formed by placing a small (or large) drop of mixture on the skin, letting the acetone evaporate, laying the bare end of the lead-off wire over the resulting silver spot, placing another drop of mixture over the wire, and letting the resulting “silver sandwich” dry. This process typically takes less than a minute, and the electrode will remain firmly in place for hours. This paper will discuss the properties of electromyographic signals gathered by means of these paint-on electrodes, as compared with those from hooked-wire electrodes inserted in the same muscles, and will mention the potential usefulness of these electrodes for investigating the development of speech and other motor control patterns in children.

Improved Cooling for Generators of Large Rating

Improved ventilation, through the increase in the mass flow of hydrogen in both rotor conductors and stator vents, has permitted increases in turbine-generator ratings. Further advances in ventilation, and thus in rating, are obtained 1) by paralleling the cooling paths in the rotor by means of zoning which employs the full fan pressure and 2) by using higher capacity gas-cooled stator coils with two sets of vent ducts per conductor with bare end connectors. Further increased stator ratings are obtained by introducing higher pressure (or higher mass flow) hydrogen to the stator coils through connectors and an external pumping system. With hydrogen cooling, substantial increases in machine ratings are now possible, within practical frame sizes and with high efficiencies, to match ratings of present-day large tandem compound turbines.

Theory of the terminated insulated antenna in a conducting medium

The general problem of the insulated antenna in an isotropic homogeneous medium of infinite extent is reviewed under the assumption that the medium is sufficiently conducting to permit the application of coaxial line theory. The currents and associated electromagnetic fields for the completely insulated antenna are obtained and the directional properties of the latter explained by comparison with a collinear array. An antenna in which only a central portion is insulated, while the ends are bare, is analyzed in terms of the theories of the insulated and bare antenna, both when the structure is driven by generators at the junctions of the bare and insulated sections and when it is driven by an internal coaxial feeder in the manner of a sleeve dipole. Finally, the center-driven insulated antenna with bare ends is investigated and its field is compared with that of the antenna driven at the junctions of the bare and insulated sections.

A Test of the Validity of the Diffusion Equation for Unsaturated Flow of Soil Water

AbstractA review of the derivation of the diffusion equation from the potential equation for unsaturated flow of liquids in porous materials reveals that the only additional assumption required is that diffusivity is a unique function of water content. The validity of this assumption is tested by following absorption of water into a horizontal column of soil with a gamma ray densitometer. To ensure that required boundary conditions were met, the soil was evacuated to eliminate entrapped air or air pressure build‐up ahead of the wetting‐front; and water was applied quickly, evenly, and at constant negative head through a plane sintered glass bead plate, pressed against the bare plane end of the column to initiate flow. Diffusivity vs. water content curves constructed from these data reveal that diffusivity is not a function of water content alone.

Plastic repair of the incontinent sphincter ani

It is reaffirmed that repair of the incontinent sphincter ani does not necessitate dissection and isolation and suture of the bare muscle ends. Instead, the use of muscle-bearing flaps is advocated. The principle was described by us several years ago in connection with one of the more unusual types of muscle injury. This paper reports an adaptation of this principle to the more common problems of repair with an even simpler operation. The technic of the operation is included and its advantages ennumerated.