Abstract: A cover (200) for inhibiting corrosion of a metallic object over which the cover is placed. The cover has an inner surface (104) defined by a liquid-permeable layer (202) and an outer surface (102) defined by a liquid-impermeable layer (204). A moisture-absorbing layer (206) is sandwiched between the liquid-permeable layer and the liquid-impermeable layer. The liquid-permeable layer allows vapor and liquid moisture beneath the cover to be absorbed into the moisture-absorbing layer to reduce the amount of moisture beneath the cover. The liquid-impermeable layer repels environmental liquid moisture, such as rain, sea spray, dew and the like and prevents such moisture from penetrating the cover. A radar-influencing layer (308) and vapor corrosion inhibitors (214) may be included in the cover. A method of protecting an object is also disclosed. The method includes covering a metallic object with cover (200).

Abstract: A freeze tolerant condenser (106) for a two-phase heat transfer system is disclosed. The condenser includes an enclosure (110) and a porous artery (112) located within and extending along the length of the enclosure. A vapor space (116) is defined between the enclosure and the artery, and a liquid space (114) is defined by a central passageway within the artery. The artery includes a plurality of laser-micromachined capillaries (130) extending from the outer surface of the artery to its inner surface such that the vapor space is in fluid communication with the liquid space. In one embodiment of the invention, the capillaries (130) are cylindrical holes having a diameter of no greater than 50 microns. In another embodiment, the capillaries (130′) are slots having widths of no greater than 50 microns. A method of making an artery in accordance with the present invention is also disclosed.

Abstract: A composite emitter (100) for a thermophotovoltaic cell and other applications, and a method of forming the composite emitter. The composite emitter includes a substrate (102) and a selective emitter layer (104) composed of at least one substantially pure ceramic oxide selective emitter material applied to the substrate using a thermal spraying method. The substrate is preferably made of a durable material such as a silicon-based material or a refractory metal oxide. In one embodiment, the selective emitter layer may be composed of two or more selective emitter materials. In another embodiment, the composite emitter may further include a reflective metal layer (106). The method includes providing a substrate and plasma spraying one or more selective emitter materials onto the substrate to a thickness of between about 10 microns and about 400 microns to form the selective emitter layer.

Abstract: A data management system (10) for managing and distributing high-speed, real-time and archived data between diverse local and remote data sources (26) and data sinks (30). The system includes a server (12) having cache memory (14) and archive memory (18) and one or more ring buffered network bus (RBNB) modules (24). Each RBNB module features a highly modular, object-oriented design, with the RBNB module being the highest level object in the system. The RBNB modules include a plurality of ring buffer objects (42) that handles data streams from data sources, a plurality of network bus objects (44) that handle data streams to a data sinks, and RBNB control objects (40) the handle connections for the ring buffer objects and network bus objects. Data is handled by the RBNB module in data frame (68) increments based on the combination of identified channels (116) and time stamps (250).

Abstract: A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300).

Abstract: A three-phase inverter for small, high speed motors such as a miniature centrifical compressor which has a low voltage, high current requirement. The inverter is supplied with DC power at 28 volts, and produces power of about 50 to 500 watts at about 15 volts, and at frequencies of about 5 to 9 kilohertz. Six D-type flip-flops with clock inputs produce twelve signals which are provided to six bridge drivers. Each bridge driver controls two MOSFET's in series. The MOSFET's are supplied with DC power. Outputs are fed to primaries of adjacent transformers in a circular array. The transformer secondaries are arranged in a star configuration to produce stepped voltage and saw-tooth current output wave forms approximating sinusoids in three phases.

Abstract: An ultrasonic transducer array having a plurality of transducer elements, at least some of which have multiple piezoelectric and electrode layers. The resonant frequency of the transducer elements may range from 500 kHz to 300 MHz or more. A single array may have transducer elements of different resonant frequencies, and the array may be sparsely populated. Highest frequencies are typically obtained when the piezoelectric layers are made from vapor deposited PZT in accordance with a disclosed deposition process. The array may have a 1-D configuration, 1.5-D or 2-D, configuration. The array may be positioned in a probe.

Abstract: An ultrasonic imaging system capable of transmitting and receiving ultrasound over a wide frequency range, i.e., 500 KHz-300 MHz. Ultrasound may be transmitted from a single transducer array at multiple frequencies simultaneously or sequentially via separate, acoustically isolated transducer elements, each having a unique resonant frequency. Signal-to-noise ratio may be enhanced through use of multiple piezoelectric layer transmit transducer elements and single piezoelectric layer receive transducer elements, both on a single transducer array. Aspect ratios approaching unity for transducer elements of the array may be obtained, which can be used to reduce grating lobes. Sparsely populated transducer arrays are included in the imaging system. Methods of ultrasound imaging and ultrasound therapy obtainable with the present imaging system are included in the invention.

Abstract: A radial position sensor includes four capacitive electrodes oriented about a shaft, arranged in two diametrically opposite pairs. Sensor circuitry generates an output signal in proportion to the capacitance between the electrodes and the shaft; the capacitance between an electrode and the shaft increases as the shaft approaches the electrode and decreases as the shaft recedes from the electrode. The sensor circuitry applies an alternating voltage to one electrode of a pair and a 180 degree out of phase alternating voltage to the other electrode of the pair. The electrical responses of the two electrodes to their respective input signals are summed to form a radial deviation signal which is relatively free from the alternating voltage and accurately represents the position of the shaft relative to the electrodes of the pair.

Abstract: An electric discharge machining power supply has a capacitor which is recharged using an inductor. After a spark, a transistor switch is closed, and energy from a source is stored in the inductor. The inductor charge period allows for deionization of the spark gap. After the desired amount of energy has been stored in the inductor, the transistor switch is opened, and the energy in the inductor is transferred to a capacitor. When the capacitor is charged, the gap voltage increases to its breakdown value for spark ignition. Because the energy transfer from the inductor to the capacitor is faster than the spark ignition delay, the capacitor is fully charged before the next spark occurs. After the spark ignition delay, a new spark is generated and the cycle is repeated. Other controls and elements are added. Gap voltage is sensed at a point intermediate two resistors between the source and the discharge electrode. A short across the gap is sensed. An inductor/transformer isolates the power source and spark.

Abstract: The present invention is directed to a compact heat exchanger having a permeable heat transfer element and an impervious heat transfer element. Fluid passes through the permeable element through passages which are substantially normal to the interface between the permeable and impervious elements. The fluid passes into channels which are provided at or near the interface between the permeable heat transfer element and the impervious element. Heat is transferred between the fluid and the permeable heat transfer element by convection as the fluid flows through the permeable element. Heat is transferred between the impervious element and the permeable element by conduction. The permeable element can be formed from one or more plates which bound one or more passages through which the fluid flows or can be formed from various porous material such as sintered powders, rods and metal foams.

Abstract: The present invention is directed to a seal for demountable joints operating over a wide temperature range down to liquid helium temperatures. The seal has anti-extrusion guards which prevent extrusion of the soft ductile sealant material, which may be indium or an alloy thereof.