DC motor proportional control system for orthotic devices

Multi-channel proportional control system for operation of dc motors for use with externally-powered orthotic arm braces is described. Components of circuitry and principles of operation are described. Schematic diagram of control circuit is provided

Lathe attachment used to machine elliptical cones

Close-tolerance elliptical cones are fabricated by cutting-tool guide assembly used with conventional tracer cartridge on turret lathe accurately produced in two machine operations

Apparatus for machining geometric cones Patent

Rotary spindle lathe attachments for machining geometrical cone

Extended range harmonic filter

Two types of filters, leaky-wall and open-guide, are combined into single component. Combination gives 10 db or greater additional attenuation to fourth and higher harmonics, at expense of increasing loss of fundamental frequency by perhaps 0.05 to 0.08 db. Filter is applicable to all high power microwave transmitters, but is especially desirable for satellite transmitters

On the use of internal state variables in thermoviscoplastic constitutive equations

The general theory of internal state variables are reviewed to apply it to inelastic metals in use in high temperature environments. In this process, certain constraints and clarifications will be made regarding internal state variables. It is shown that the Helmholtz free energy can be utilized to construct constitutive equations which are appropriate for metallic superalloys. Internal state variables are shown to represent locally averaged measures of dislocation arrangement, dislocation density, and intergranular fracture. The internal state variable model is demonstrated to be a suitable framework for comparison of several currently proposed models for metals and can therefore be used to exhibit history dependence, nonlinearity, and rate as well as temperature sensitivity

The Production of HI in Photodissociation Regions and A Comparison with CO(1-0) Emission

The gas at the surfaces of molecular clouds in galaxies is heated and dissociated by photons from young stars both near and far. HI resulting from the dissociation of molecular hydrogen H2 emits hyperfine line emission at 21 cm, and warmed CO emits dipole rotational lines such as the 2.6 mm line of CO(1-0). We use previously developed models for photodissociation regions (PDRs) to compute the intensities of these HI and CO(1-0) lines as a function of the total volume density n in the cloud and the far ultraviolet flux G0 incident upon it and present the results in units familiar to observers. The intensities of these two lines behave differently with changing physical conditions in the PDR, and, taken together, the two lines can provide a ground-based radio astronomy diagnostic for determining n and G0 separately in distant molecular clouds. This diagnostic is particularly useful in the range Gzero <~ 100, 10 cm^{-3} <~ n <~ 10^5 cm^{-3}, which applies to a large fraction of the volume of the interstellar medium in galaxies. If the molecular cloud is located near discrete sources of far-UV (FUV) emission, the PDR-generated HI and CO(1-0) emission on the cloud surface can be more easily identified, appearing as layered ``blankets'' or ``blisters'' on the side of the cloud nearest to the FUV source. As an illustration, we consider the Galactic object G216 -2.5, i.e. ``Maddalena's Cloud'', which has been previously identified as a large PDR in the Galaxy. We determine that this cloud has n ~ 200 cm^{-3}, G0 ~ 0.8, consistent with other data.Comment: 13 Pages, 3 Figures. Accepted for publication in the Astrophysical Journa

Method and apparatus for aligning a laser beam projector Patent

Laser beam projector for continuous, precise alignment between target, laser generator, and astronomical telescope during trackin

Method of directing a laser beam with very high accuracy

System will collimate and direct an argon laser beam with high angular tracking accuracy at objects on the moons surface. It can be adapted to missile and satellite tracking

Computing the local pressure in molecular dynamics simulations

Computer simulations of inhomogeneous soft matter systems often require accurate methods for computing the local pressure. We present a simple derivation, based on the virial relation, of two equivalent expressions for the local (atomistic) pressure in a molecular dynamics simulation. One of these expressions, previously derived by other authors via a different route, involves summation over interactions between particles within the region of interest; the other involves summation over interactions across the boundary of the region of interest. We illustrate our derivation using simulations of a simple osmotic system; both expressions produce accurate results even when the region of interest over which the pressure is measured is very small.Comment: 11 pages, 4 figure