Abstract: A circuit for converting a DC voltage to a pulsating DC voltage useful as a power source for operating an AC machine. The circuit includes means for controlling the amplitude of the pulsating DC voltage as the load changes and means for controlling the duration of the pulses comprising the pulsating DC voltage.

Abstract: A switching device including four layers (20), (22), (42) and (44) and a gate electrode (32). In its blocking state the switching device operates as a conventional thyristor. The device is turned off by reducing the effective resistance of the upper base region (42) by applying a negative voltage to the gate (32).

Abstract: The invention provides a disc for use in varistors. The disc is primarily composed of ZnO and includes predetermined concentrations of Bi.sub.2 O.sub.3 in a selected ratio with Sb.sub.2 O.sub.3.

Abstract: A method for fabricating a valve includes hardened valve seats and a conventional valve stem which mates with the hardened valve seat. A valve seat support ring is attached to the body of the valve and to the hardened valve seat. HIP bonding is utilized to bond the hardened valve seat to the valve seat support ring. Conventional techniques, such as welding are used to attach the valve seat support ring to the body of the valve.

Abstract: A varistor utilizing a disc of mainly ZnO in combination with preselected combinations of Bi.sub.2 O.sub.3, Sb.sub.2 O.sub.3, SiO.sub.2, MgO and CaO.

Abstract: A method for making a varistor disc with increased high temperature stability. The method includes the steps of formulating a mixture for the varistor disc, compacting the mixture to form a disc, sintering the disc at a first preselected temperature and cooling the disc at a predetermined linear rate. The predetermined linear rate and preselected temperature are selected to reduce nonequilibrium conditions which become "frozen-in" as said disc is cooled.

Abstract: The vaneless rotary airlock valve of this invention is designed to overcome the deficiencies of excessive leakage, excessive wear, and product degradation associated with conventional vaned rotary airlocks. It is comprised of a vaneless rotor (a cylindrical or barrel-like container), a pair of sealing rings (one on the upstream side and one on the downstream side of the rotor), and (depending on the operating conditions) a pair of either compression or expansion rings which urge continuous sealing engagement between the sealing rings and the rotor.

Abstract: An eddy current sensor probe which includes first and second rigid end portions coupled together with a central portion comprising a flexible membrane. The flexible membrane includes indentations comprising sensor supporting regions. A differential pressure is applied across the membrane to position the sensors in a favorable location for collecting data related to the condition of the wall portion of hollow tubes.

Abstract: A layer or coating bonded to a substrate is encapsulated to prevent portions of the layer from becoming detached and randomly distributed. This is accomplished by applying a first layer of an adhesive to the exposed surface of the layer to be encapsulated. A second layer composed of a fibrous material is placed in contact with the first layer of adhesive and then an additional layer of adhesive is applied by a suitable technique such as brushing or coating. The additional layer of adhesive penetrates the fibrous material forming a stratified layer composed of an outer layer primarily of the adhesive, an intermediate layer composed primarily of a mixture of adhesive and fibrous material and an inner layer including the exposed surface layer and portions of the adhesive. The method is useful for encapsulating potentially hazardous materials such as lead based paints and asbestos.

Abstract: A utility meter including an electronic module to calculate predetermined parameters related to electric utility line and load conditions. Signals related to utility line voltage and load conditions are scaled and sampled to generated a data base which is utilized by a digital processor to calculate the parameters discussed above. Calibration processes controlled by the processor corrects for errors related to the sensors used to sense line voltage and load conditions as well as drift in the analog portions of the electronic module.

Abstract: The invention comprises a DC link resonant converter for controlling the speed of AC machines. Switch and power supply means is provided to establish a bi-directional initial current in the resonant circuit. By selecting the plurality and magnitude of the initial current, the peak voltage of the resonant link is controlled, and reliable zero crossing of the resonant voltage is assured. Current technology permits resonant frequencies in the range of 50-100 kilohertz to be utilized.

Abstract: Apparatus controls a power converter 34 to interchange power between first and second electric sources, 30 and 32. Typically the first source 30 is a standard utility bus and the second source 32 is a storage battery. A controller generates control signals in response to the utility bus voltage, to a command specifying the required power interchange and to a feedback signal indicative of the actual power being interchanged. These signals control the power converter 34 to produce the required power interchange.

Abstract: An array of SQUID detectors to map the magnetic field associated with test currents flowing in the component to be tested. The SQUID is an ultrasensitive, miniature device that transduces a faint magnetic field to a measurable voltage. Perturbation occurs in the test currents and the associated magnetic field at physical defects or inhomogeneities. Multi-dimensional test currents are injected into the component being tested; the injection being made between specific electrodes by varying the direction of the current until it is normal to the direction of the defect to maximize and amplify the effect of the perturbation. The perturbation is detected by the SQUID grid which pinpoints the location, orientation, and size of the defect. The frequency of the injected current can be made to sweep the spectrum from DC to the highest response limit of the SQUID to scan for defects at various depths.

Abstract: The invention provides a tool useful as an aid in joining pipes by welding. The tool includes means for positioning and holding an insert ring in a predetermined position with respect to the end of a pipe while the insert ring is tack-welded to an end of the pipe. Means is also included permitting the ends of the pipe to be welded to be aligned.

Abstract: The invention provides an improved pulse initiator circuit for attaching to utility meters to generate a pulse signal having a predetermined relationship to the rate of power usage measured by the utility meter. Electronic circuitry is utilized which automatically compensates for differences in individual utility meters permitting the pulse initiator to be used with any standard utility meter without calibration or adjustemnt. The pulse initiator is attached to the utility meter without breaking the meter seal.

Abstract: The invention provides apparatus and a method for making slush ice. A liquid is directed to flow over a hot exchanger to cool the liquid and form slush. By selecting the constituents of the liquid such that the adhesion and cohesion forces are controlled to permit harvesting the slush while substantially all of the energy required by conventional harvesting cycles is saved.

Abstract: Fabrication of the test structure is functionally illustrated in FIG. 9. More specifically, the first step in the process is to machine the cavity 40 in the third body of austenitic material 42, as functionally illustrated at reference numeral 80. After the cavity 40 has been machined, the fault sample 34 is installed into the cavity by heating the third body of austenitic material 42 and cooling the fault sample 34. This process is functionally illustrated at reference numeral 82. After installation of the fault sample 34, the interface is welded to seal the junction and the combined structure HIP bonded, as functionally illustrated at Reference Numerals, 84 and 86. After bonding the test structure is machined into the desired configuration, as functionally illustrated at Reference Numeral 88.

Abstract: The invention provide an improved trailer dolly and an improved trailer dolly tongue support jack. More specifically, the invention provides a trailer dolly which includes a tongue support jack which is effective and convenient to operate. In the preferred embodiment, the improved dolly includes a tongue support assembly permits the dolly tongue jack to be rotated between and automatically locked in the tongue support positions and the trailer use positions. Although the tongue jack was developed primarily for use with trailer dollys it can be used to support conventional trailer tongues and similar uses.

Abstract: The invention provides an improved package and packaging method for products that contain moisture. In the preferred embodiment, the product to be packaged is placed in a tray and the product and the tray are wrapped with a transparent film. The film is selectively affixed to at least a portion of the bottom of the tray using a heat-activated adhesive to form a leak-resistant package.

Abstract: A plasma torch head adapted to cut longitudinal slots in tubes from the interior is disclosed. The plasma torch head includes an outer body made of reinforced fiberglass. An adhesive is used to affix fiberglass components of the torch head together to form a gas tight seal. As a cut is made, the outer body of the torch becomes charred. At the end of each cut the torch head is either replaced or rebuilt. Gas to support the plasma and electric power is supplied to the torch head via an electrically conductive tube concentric with the major axis of the torch head.