Abstract: A portable spa cover having three rigidly molded, interlocking pieces including two mirror image end pieces and a center piece and designed to conform with the contour of the rim of a spa. Each cover piece has an undersurface and outer surface with a plurality of radial support ribs being formed in the undersurface to provide strength and rigidity. Elongated, tapered male and female hinge members are integrally molded as part of the respective end pieces and center piece and permit the cover pieces to be engaged and disengaged from one another when at an angle with respect to one another, while remaining firmly locked together when the pieces all lie horizontally. The horizontal engagement is further facilitated by resilient fingers which extend out from the male projection at intervals along the cover edge and provide a resiliently biased interlocking mechanism.

Abstract: A portable spa including a cover having two rigidly molded, interlocking halves, designed to conform with the contour of the rim of the spa. The rim includes a vertical extension which interfits with an extrusion used to attach an interchangeable decorative vinyl-covered skirt about the side surface of the spa. The spa structure is supported by an integral molded bottom pan, which provides an upper edge or rim against which the lower edge of the skirt is secured.

Abstract: A pulse train generator is formed of a series of cascaded stages, each of which operates in response to pulses to generate twice as many output pulses with the same spacing and height. Each stage is formed of a transmission line network and a MESFET amplifier. The input gate of each MESFET is shunted by a matching resistor while the output of the MESFET is coupled to the transmission line network through the drain terminal. The transmission line network is substantially matched to the combined impedance of the load resistor and the MESFET. The generator may be arranged to generate radio frequency waveforms.

Abstract: One-shot, flexible polyurethane foams capable of being thermally bonded to various substrates are produced by adding low molecular weight alkylene glycols, glycol ethers, triols, alkanolamine, or polyhydric phenols as modifiers to conventional polyisocyanate foaming mixtures.

Abstract: The present invention relates to a method of producing pile or plush goods or fabrics on circular knitting machines with plush hooks in the cylinder and latch needles in the dial and circular double knitting machines by means of pile hooks in a needle bed. Certain selected pile hooks are raised prior to the needles in order to prevent the fabric from raising with the needles while the pile hooks which are not selected for the formation of pile loops are retracted prior to the feeding of the pile yarn. Subsequent to the formation of the pile loops, the pile hooks are advanced into the loop forming position by the stitch cam until the needles move into an inactive position after the stitch formation, in order that the stitches are relieved (from tension) and withdrawn from the dial.

Abstract: Cellular urethane polymers essentially free of the strong, objectionable amine odor characteristic of N-ethylmorpholine, are provided by effecting the polyurethane forming reaction in the presence of beta-tertamino nitriles. In view of their low residual odor and effectiveness in the catalysis of the water-isocyanate reaction, the beta-amino nitriles either alone or in combination with other tertiary amines, are used with particular advantage as direct replacements for N-ethylmorpholine in the manufacture of water-blown flexible polyurethanes, both molded and free-rise, including high-resilience foam as well as foams stabilized with either organosilicone or silicon-free organic surfactants. Especially effective for the formation of flexible polyester foam stabilized with either type of surfactant are blends of the beta-amino nitrile catalyst such as, in particular, 3-(N,N-dimethylamino)propionitrile, with dimethylethanolamine or a bis[2-(N,N-dimethylamino)alkyl]-ether.

Abstract: The amplifier configuration includes a double-to-single ended converter having two interconnected portions, each having three signal paths. Two of the signal paths include transistors of a first conductivity type having main electrodes coupled between one of the output terminals of a differential amplifier and a power supply conductor. The other path includes a transistor of the second conductivity type having a control electrode coupled to one of the differential amplifier output terminals and main electrodes coupled between power supply conductors. Identical current sources drive corresponding transistors of each portion. The transistors of the second conductivity type enable quiescent voltages of only one base-to-emitter voltage drop to be developed at each of the output terminals of a differential amplifier to facilitate balance and maximization of the dynamic signal range.

Abstract: A flying ship is disclosed which comprises a hollow, saucer-shaped body having a convex upper surface surmounted at its center portion by a dome-shaped transparent canopy covering a passenger compartment, and a bottom including a generally concave major bottom portion, and an annular outer bottom portion which is inclined upwardly at its outer edge and is joined to the concave major bottom portion by a smooth upwardly open curve. Plural jet engines are adjustably mounted beneath the ship in a circular pattern inward of the outer edge and beneath the annular outer bottom portion to provide lift for take-off and landing, and horizontal thrust, as well as lift, for flight. An annular fluid motor is provided in the ship above the jet engines which includes an annular tube in which, an endless train of pistons is slidably mounted.

Abstract: The present invention provides a method of producing double-knit goods or fabrics having additional fleece threads incorporated into one face or both faces thereof and a nap or fleece is imparted from these threads by napping. The method comprises feeding the backing or ground yarn only to the needles of both needle sets (dial and cylinder) which are fully raised for stitch formation, while feeding the additional fleece thread to the needles of one needle-set (cylinder) which form stitches and tuck loops, and/or feeding the backing yarn and the additional fleece thread in successive steps of operation and knitting them into common stitches on one needle set (dial) and into stitches and tuck loops on the other needle set (cylinder).

Abstract: A controlled interval pulse train generator comprising a plurality of three terminal transferred electron logic devices, and a delay line. The generator produces a train of small pulse-width voltage pulses at intervals determined by the delay line. The pulse train is started in response to an initial pulse and is terminated in response to a voltage step.

Abstract: A varactor tuning apparatus for tuning a strip transmission line radio frequency device, wherein the device having predetermined operating characteristics includes an active element such as an avalanche diode and a resonant conductive strip section. The tuning apparatus comprises a separate varactor circuit having a varactor mounted on a dielectric substrate including a resonant conductive strip. The varactor circuit is RF coupled to the strip transmission line of the device to provide for tuning the device by varying the reactance of the strip transmission line by electrically changing the capacitance of the varactor.

Abstract: A current limit circuit is disclosed for sensing the current drain of a load connected in series therewith. Under normal operating conditions the circuit presents a relatively low impedance in series with the load. Circuit overload protection is provided if the current increases above a predetermined value by a current limiting circuit provided for limiting the current conducted therethrough. In response to the current limiting condition, thermal shutdown of the circuit occurs to reduce the current that is supplied to the load to a predetermined minimum value i.e., the current limit circuit presents an impedance to the load which is relatively much greater than the impedance of the current limit circuit during normal operating conditions. After a predetermined time, the current limit circuit is again rendered operative and if the circuit overload condition is still present the aforedescribed cycle is repeated until the fault condition is corrected.