Abstract: A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil.

Abstract: A traveling-wave device is provided with the conventional moving pistons eliminated. Acoustic energy circulates in a direction through a fluid within a torus. A side branch may be connected to the torus for transferring acoustic energy into or out of the torus. A regenerator is located in the torus with a first heat exchanger located on a first side of the regenerator downstream of the regenerator relative to the direction of the circulating acoustic energy; and a second heat exchanger located on an upstream side of the regenerator. The improvement is a mass flux suppressor located in the torus to minimize time-averaged mass flux of the fluid. In one embodiment, the device further includes a thermal buffer column in the torus to thermally isolate the heat exchanger that is at the operating temperature of the device.

Abstract: An orifice pulse tube refrigerator (PTR) having a pulse tube and a reservoir with a compliance value C is provided with a variable acoustic impedance connecting the pulse tube and the reservoir. The variable acoustic impedance includes two or more variable impedances, which may be an inertance and valves forming variable resistive members, wherein the resulting acoustic impedance has a phase angle that is variable for improved cooling efficiency. The inertance may also be variable to further provide for varying the phase angle. In another improvement, an acoustic transmission line connects the pulse tube and a driver unit for recovering power from the pulse tube for return to the driver to further increase the PTR operating efficiency.

Abstract: Autophase stability is provided for a traveling wave device (TWD) electron beam for amplifying an RF electromagnetic wave in walls defining a waveguide for said electromagnetic wave. An off-axis electron beam is generated at a selected energy and has an energy noise inherently arising from electron gun. The off-axis electron beam is introduced into the waveguide. The off-axis electron beam is introduced into the waveguide at a second radius. The waveguide structure is designed to obtain a selected detuning of the electron beam. The off-axis electron beam has a velocity and the second radius to place the electron beam at a selected distance from the walls defining the waveguide, wherein changes in a density of the electron beam due to the RF electromagnetic wave are independent of the energy of the electron beam to provide a concomitant stable operating regime relative to the energy noise.

Abstract: An interactive aerobic exercise machine has a support frame assembly with two parallel, spaced apart vertical frames, an obstacle rod rotatably mounted on each vertical frame, and a motor for rotating each obstacle rod at selected rotation speeds. The rotating obstacle rods allow a user to exercise a variety of different muscles while the user is also developing depth perception, timing, reaction, agility, coordination, and aerobic fitness. In a particular embodiment, each motor is slidably mounted on the vertical frame for vertically positioning the obstacle rods at a variety of vertical locations. The machine may further include a crank rod connected to the motor and a pivot block assembly connecting the crank rod to the obstacle rod, where the pivot block assembly permits the obstacle rod to move in any direction in response to encountering an obstacle to prevent injury to a user.

Abstract: An air conditioner system has a boiler for generating a refrigerant vapor from a liquid refrigerant therein and a condenser for condensing the refrigerant vapor to the liquid refrigerant. An expander connects the boiler and the condenser to generate output energy when the refrigerant vapor passes therethrough from the boiler to the condenser in a first direction. A fan produces an ambient air flow through the boiler and the condenser to provide heat input for vaporizing the liquid refrigerant in the boiler and cooling the air flow and for extracting heat from the condenser to condense the refrigerant vapor to the liquid refrigerant. A water mist is generated that contacts the air flow intermediate the boiler and the condenser for further cooling the air flow through heat of vaporization of the water so that air exiting the condenser is cooler than the ambient air flow entering the boiler.

Abstract: A power generating system is powered by a circulating working fluid that is heated by heat of condensation deposited in a concentrated brine solution. The brine solution is concentrated by introducing a relatively dilute brine solution at a first location in a brine concentrator and collecting a relatively concentrated brine solution formed from the relatively dilute brine solution at a second location in the brine concentrator. A dry air flow is introduced at the second location and directed toward the first location to maintain a differential partial pressure between the air flow and the brine solution effective to evaporate solvent from the brine solution as the brine solution moves from the first location to the second location.

Abstract: A general purpose computer operating system is run using a real time operating system. A real time operating system is provided for running real time tasks. A general purpose operating system is provided as one of the real time tasks. The general purpose operating system is preempted as needed for the real time tasks and is prevented from blocking preemption of the non-real time tasks.

Abstract: A bubble chamber spectrometer provides a new method for the sensitive detection of an analyte in a solvent. A bubble chamber receives a solution containing an analyte to be detected. A laser is adapted to direct an output laser beam through the bubble chamber, where the laser is selected to be absorbed by the analyte and to be transmitted by the solvent. A video camera is adapted to display passage of said laser beam through said bubble chamber so that bubbles in the solvent arising from energy deposition in the analyte can be counted to characterize the analyte both quantitatively and qualitatively.

Abstract: A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a TM.sub.0n mode. A waveguide defines an axial centerline and, a solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.

Abstract: A self-seeded free electron laser (FEL) provides a high gain and extraction efficiency for the emitted light. An accelerator outputs a beam of electron pulses to a permanent magnet wiggler having an input end for receiving the electron pulses and an output end for outputting light and the electron pulses. An optical feedback loop collects low power light in a small signal gain regime at the output end of said wiggler and returns the low power light to the input end of the wiggler while outputting high power light in a high signal gain regime.

Abstract: Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

Abstract: A polymer electrolyte membrane fuel cell assembly has an anode side and a cathode side separated by the membrane and generating electrical current by electrochemical reactions between a fuel gas and an oxidant. The anode side comprises a hydrophobic gas diffusion backing contacting one side of the membrane and having hydrophilic areas therein for providing liquid water directly to the one side of the membrane through the hydrophilic areas of the gas diffusion backing. In a preferred embodiment, the hydrophilic areas of the gas diffusion backing are formed by sewing a hydrophilic thread through the backing. Liquid water is distributed over the gas diffusion backing in distribution channels that are separate from the fuel distribution channels.

Abstract: A sealing system provides for plugging holes in a ferromagnetic tank structure. A tripod has variable length legs for placing on a curved or irregular surface of the tank structure. A permanent magnet assembly is attached to each one of the variable length legs for removably attaching the legs individually to the ferromagnetic tank structure. An actuator is mounted in the tripod for positioning over the hole for movement generally perpendicular to the tank structure in which the hole is located. A clamping plug is mounted on the actuator for insertion into and sealing the hole.

Abstract: Relevant resonance response characteristics of a sample are determined for use in characterizing the sample for non-destructive testing. The sample is excited by an exciting mechanical input at a plurality of ultrasonic frequencies. The response is separated into in-phase and quadrature components and the resonance response characteristics are computed from the in-phase and quadrature components. Apparatus for obtaining the relevant response characteristics includes a frequency generator for inputting an exciting ultrasonic frequency to the sample. A transducer outputs a response of the sample to the exciting ultrasonic frequency. A dynamic signal analyzer is connected to receive the response of the sample and to output in-phase and quadrature components of the response of the sample. A computer then determines the relevant response characteristics from the in-phase and quadrature components.

Abstract: This fabric stretching system for artists' canvases, silk screens, and the like, utilizes extruded, specially profiled, wood-like material in place of conventional wooden bars to form a frame on which canvas is stretched. Each corner of the frame is joined by two identical corner braces, which mate to profiled features of the frame and lock the bars rigidly together. The extruded frame material, which is made from recycled wood and other organic materials held in a plastic binder, maintains the weight and feel of traditional wooden frames but is free of many of the disadvantages of wood. The material as extruded is ready for use. It needs only to be cut to the desired length, an operation which can be done with a simple miter saw. Two braces are used in each corner, the second containing adjustment screws for tensioning. This arrangement makes for simple assembly and assures a rock solid frame which can be adjusted to provide additional tension on the canvas at time of assembly or at any future time.

Abstract: A method is provided for directly determining the length of sub-picosecond electron bunches. A metallic grating is formed with a groove spacing greater than a length expected for the electron bunches. The electron bunches are passed over the metallic grating to generate coherent and incoherent Smith-Purcell radiation. The angular distribution of the coherent Smith-Purcell radiation is then mapped to directly deduce the length of the electron bunches.

Abstract: A hardened image is removed from printing plates by a solution of formic acid and hydrofluoric acid. In one embodiment, the solution further includes a buffer solution to maintain the oleophilic properties of the substrate for printing.

Abstract: An inverting liner system is used for installing a casing in a borehole without the need for drilling mud. The liner system includes a first portion with a diameter effective for supporting walls of said borehole and a second portion having a first end fixed to the liner portion at a point of attachment and a second distal end. The second liner portion has a diameter effective for surrounding the casing and inverting the casing within the first liner portion. A third liner portion has one end attached to the point of attachment of the first and second liner portions and a second end releasably attached to the distal end of the second liner portion during installation of the casing in the borehole. When casing installation is complete, the third liner portion is released from the second liner portion and the third liner portion may be withdrawn from the borehole, thereby inverting the first and second liner portions from about the casing and from within the borehole.

Abstract: A computer-implemented method identifies a script used to create a document. A set of training documents for each script to be identified is scanned into the computer to store a series of exemplary images representing each script. Pixels forming the exemplary images are electronically processed to define a set of textual symbols corresponding to the exemplary images. Each textual symbol is assigned to a cluster of textual symbols that most closely represents the textual symbol. The cluster of textual symbols is processed to form a representative electronic template for each cluster. A document having a script to be identified is scanned into the computer to form one or more document images representing the script to be identified. Pixels forming the document images are electronically processed to define a set of document textual symbols corresponding to the document images. The set of document textual symbols is compared to the electronic templates to identify the script.