US Government As Represented by the Secretary of the Army

Donald E Wortman

Richard P Leavitt

Clyde A Morrison

Nick Karayianis

John D Bruno

Herbert Dropkin

Frank J Crowne

Thomas B Bahder

John L Bradshaw

Romel D Gomez

A valve-less fluid control circuit for controlling rhythmic action devices, such as circulatory assist devices. The fluid control circuit has a plurality of pressure sensitive fluid oscillators for circulating a fluid. Each fluid oscillator includes a capacitance chamber unit for peristaltic pumping of fluid after being filled via an input conduit and a resistance conduit. A first control conduit provides an outlet of fluid from the capacitance unit during peristaltic pumping, and when the pressure of the fluid in the first control conduit reaches a certain level relative to the pressure of fluid in the input conduit, the fluid is directed through an interactive region and exits the first fluid oscillator through an exhaust conduit. A coupling unit couples the output of the first fluid oscillator to the input conduit of the successive fluid oscillator, so that the expansion and contraction of the capacitance chambers occurs successively without the need for valves and/or complicated control circuitry, such as solenoids and cams. A return conduit at the last fluid oscillator returns the fluid to a second control conduit of the first fluid oscillator to refill the first capacitance chamber.

Valve-less fluid control circuit for rhythmic action devices

A method for improving images of surface features of a sample, constructed by a scanning probe microscope, includes constructing images of surface features of a sample with a scanning probe microscope; measuring a displacement of the sample that occurs during the constructing step; and correcting the images using the measured displacement. An apparatus for improving images of surface features of a sample, constructed by a scanning probe microscope, includes a vacuum chamber; a sample holder disposed in the vacuum chamber; at least one spring connected between the vacuum chamber and the sample holder; at least one magnet disposed in the vacuum chamber for damping vibrations of the sample holder; a probe and piezo tube assembly disposed in the vacuum chamber for scanning surface features of a sample; and an interferometer disposed in the vacuum chamber wherein the interferometer measures a distance between the sample and a point fixed with respect to the sample.

Vibration distortion removal for scanning probe microscopes

An electromagnetic launcher includes a single or multi-polar, multi-phase electrical generator powered by an external source; electrical conductors leading from output coils of the generator and from a center point joining the output coils; a plurality of rails connected to the electrical conductors; and an armature having at least two channels; whereby there is at least one position of the armature along the plurality of rails where current flows simultaneously through both of the at least two channels.

Electromagnetic launcher with pulse-shaping armature and divided rails

An apparatus for determining thickness of a wall or coal seam includes a ice for measuring the time of sound travel through the thickness; a flexible isolation bellows that mechanically supports the device for measuring the time of sound travel; and a retractable isolation arm attached to the isolation bellows. The device for measuring the time of sound travel may be a single-beam pulse sonar system. The single-beam pulse sonar system includes a pulse generator, a power amplifier, a transmit/receive switch, a reciprocal acoustic transducer, a receiver for determining the thickness, and a display and/or an electronic feedback circuit for steering an autonomous miner.

Acoustic navigation aid for autonomous coal miner

A method and apparatus for controlling a chemical reaction by heterogeneous catalysis, in which a surface acoustic wave (SAW) is propagated along a surface of a piezoelectric element in contact with liquid or gaseous substances to be chemically reacted, to thus generate an electric field at the surface of the element which initiates and sustains the desired reaction. The catalysis rate can be varied by varying the frequency and/or intensity of the surface acoustic wave. The surface of the element may be coated with a very thin film of a catalytic group 8 metal which can be penetrated by the SAW electric field. In such an embodiment, normal catalysis proceeds via chemisorption, and the SAW element field acts to increase the catalysis rate.

Method for chemical reaction control using a surface acoustic wave device

An orotron for generating near millimeter wavelength radiation at a selectable output frequency within a wide frequency range, in which the orotron output power is automatically tuned electronically at the selected output frequency. A piezoelectric electromechanical positioning device is connected between the two mirrors forming the open resonator of the orotron to determine the mirror separation in accordance with a position control signal. The electron beam acceleration voltage, which determines the orotron output frequency, and the position control signal are adjusted simultaneously so as to tune the output power at a single oscillation mode of the orotron resonator over a wide frequency range. In the preferred embodiment, the actual output frequency is detected and compared with the selected output frequency, and the beam acceleration voltage and mirror separation simultaneously adjusted to continuously tune and maintain the orotron output at the selected frequency.

Wideband electronic frequency tuning for orotrons

A method and apparatus for transmitting laser signals through fog, in which a laser signal directed into the fog is amplitude modulated at one or more resonant frequencies of the water droplets forming the fog at such strength as to cause the droplets to burst, thereby decreasing the scattering of the laser signal and increasing the transmission of this signal through the fog.

Method and apparatus for transmitting a laser signal through fog

Method and apparatus for modulating coherent radiation generated by an orotron in accordance with a low voltage control signal applied to the diffraction grating to vary the grating-to-cathode voltage from the cathode-to-collector voltage over a selected voltage range determined by the maximum and minimum values of the control voltage. For amplitude modulation, the grating-to-cathode voltage is varied within a voltage range between a lower voltage at which the orotron output power starts to fall abruptly and a cutoff voltage at which coherent radiation ceases. For frequency modulation, the grating-to-cathode voltage is varied within a voltage range, including the point of maximum power output, where there is a minimum change of output power with a change in the grating-to-cathode voltage.

Method and apparatus for modulating a diffraction radiation generator

A method and apparatus for increasing the power output and efficiency of an orotron generating near millimeter wavelength radiation. In accordance with a theory of orotron operation described herein and confirmed experimentally, the ribbon-like electron beam utilized in the orotron has a very high current density to effect a large increase in orotron output power and efficiency due to space-charge effects in the beam. In the preferred embodiment, the high density electron beam is generated by a closely-packed rectangular array of field-emission cathodes.

High performance orotron utilizing a dense electron beam

A diffraction radiation generator in which a ribbon electron beam is directed over a diffraction grating within an open resonator at a selected velocity to generate coherent radiation. After passing through the open resonator, the ribbon beam is directed through aligned slits in two or more conductive elements to a collector. Progressively negative voltages relative to the grating voltage can be applied to the elements and the collector to decelerate the electrons forming the ribbon beam and thus minimize heating of the collector and increase the operating efficiency of the generator. Also, the elements and the collector can be utilized to analyze the ribbon beam.

Depressed collector/ribbon electron beam analyzer for a diffraction

A high frequency electromagnetic wave generator is disclosed which comprises an electron gun which directs an electron beam through a region generally adjacent a diffraction grating. The grating cooperates with an opposed reflecting surface to produce a standing electromagnetic wave. The reflector comprises a highly reflective dielectric coated mirror. Supporting means for the diffraction grating may also comprise a reflective dielectric surface.

Near millimeter wave generator with dielectric cavity

A method and apparatus for determining aerosol size distributions, in which he droplets of an aerosol region are placed in an amplitude modulated electric field, which produces resonant elongation and contraction of particularly sized droplets, in the form of mechanical oscillations, depending on the modulating frequency of the modulated electric field. A light beam is directed against the oscillating droplets and scattered thereby, with the intensity of the scattered light beam varying as a result of the changing reflection surfaces presented by the oscillating droplets. Differently sized drops are sequentially resonantly oscillated by selectively varying the modulation frequency of the electric field, with the varying intensity of the oscillating droplets at each modulation frequency yielding the size distribution of a given aerosol.

Method and apparatus for determining aerosol size distributions

A generator for variable frequency submillimeter waves launches surface astic waves in piezoelectric material for generation of an associated acousto-electrical field. An electron beam is acted upon by the acousto-electrical field in a manner simulating the effect of an etched grating, resulting in an output frequency which may be varied by the variation of the acoustic wave frequency, or the velocity of the electron beam.

Submillimeter wave generation using surface acoustic waves in

A rare earth semiconductor laser is disclosed comprising a semiconductor erial of the type Ln.sub.2 TX.sub.5 where Ln is a rare earth element, T is zirconium or hafnium, and X is sulfur or selenium. The semiconductor contains neodymium as a dopant rare earth ion and can be made to lase by applying an electric voltage.

Rare earth semiconductor laser

A mine detector system that utilizes an explosive comparator to increase sensitivity and selectivity. The system utilizes a generator to transmit a signal simultaneously toward the area to be scanned for mines and towards a sample of the explosive sought. Detectors are positioned within the device to receive the reflected signals from both the area to be scanned and the sample explosive. The outputs from both detectors are fed to preferably a null type comparator for correlation. When the two signals correlate, mine presence is indicated.

Growing community of inventors

Rockville, MD, United States of America

Donald E Wortman