Abstract: Fibrous PAN material in raw or oxidized form is purified of alkali metals, particularly sodium, and alkaline earth metals by treating with an aqueous acid solution such as hydrochloric acid having a concentration of at least 0.5% by weight and preferably at least 3% and a temperature greater than 100.degree. F. and preferably at least 125.degree. F. but not greater than the temperature at which the aqueous acid solution boils, for 5-120 minutes and preferably at least about 15 minutes. An ion exchange occurs between the acid and the PAN material, and alkali and alkaline earth metal salts are formed. The PAN material is then rinsed in solvent such as deionized water which is substantially free of metallic ions at a temperature which is preferably at least about 150.degree. F.

Abstract: In an impact printer system in which various hammer springs mounted in side-by-side relation along a reciprocating hammer bank are selectively released to cause an impact tip mounted at the upper end of the hammer spring to impact a paper or other printable medium, the hammer springs are divided into two different groups and the release of the hammer springs in the different groups is staggered. Alternate ones of the hammer springs comprise a first group of hammer springs which are selectively released at the beginning of each of a succession of cycles as the hammer bank sweeps across the printable medium. The remaining ones of the hammer springs comprise a second group and are releaseable at a midway point through each cycle.

Abstract: A seat suspension system, which includes a height adjustment valve for positioning a seat at a desired height in response to manual positioning of a height adjustment lever by controlling the amount of hydraulic fluid supplied to a cylinder having a piston therein coupled to the seat, provides damping of vertical motion of the seat by an accumulator coupled to the cylinder via a conduit so as to receive the hydraulic fluid from the cylinder and two different valves disposed in the conduit. A manually adjustable flow control valve has an adjustable orifice within the conduit for providing the seat with a nominal amount of damping.

Abstract: Disposable receptacles for storing articles in sterile condition and having breather means integral with the walls thereof, as well as apparatus and methods for making such receptacles and the materials therefor, are disclosed. The receptacles are fabricated of a laminate comprising a layer of breathable barrier material such as paper and a layer of thermoplastic, polymeric material such as polyethylene.The breather means may be made by heat sealing the thermoplastic layers of a pair of laminated sheets together at small, selected areas and then separating the sheets causing localized delamination of the layers and the formation of ruptured, blister-like projections in the thermoplastic layers at the heat seal positions.

Abstract: An overspray filter collector unit for a plasma spray system filters fine, relatively small particulate from the overspray upstream of the vacuum pumps. The filter collector unit includes a hollow tank having a pool of oil at the bottom thereof having a top surface onto which the overspray is directed from an inlet conduit. Some of the particulate matter is deposited in the oil and at the same time oil droplets and vapor are entrained in the overspray as it deflects from the oil surface into a tortuous path defined by a plurality of baffles within the tank. The baffle surfaces are wetted by the oil vapor and droplets, and the resulting oil coating entraps the remaining particulate in the overspray before the overspray exits via an outlet conduit to the vacuum pumps.

Abstract: A compact self-sterilizable proportioning hemodialysis system alternatively usable with either a coil type or parallel flow artificial dialyzer without material alteration comprises a hydraulic driven dialysate proportioning pump in a positive pressure flow path to provide dialysate in a controlled concentration to a dialysate receiving canister. A coil-type dialyzer within the canister receives dialysate in a recirculating flow from a circulation pump. A venturi in the recirculating flow path provides a negative pressure to pull dialysate through a suction loop, which may alternatively include a parallel flow dialyzer. A conductivity cell, temperature monitor and blood leak detector sample and monitor dialysate from the canister, and to control the dialysate and indicate fault conditions. The system may alternatively function as a recirculating plate-type dialyzer having high dialysis efficiency.

Abstract: A system for operating a hydraulic tool is disclosed in which heated hydraulic fluid being returned to a fluid reservoir from the tool is cooled by a refrigeration system. The heated hydraulic fluid is introduced into the hollow interior of a distributor from which the fluid exits through a plurality of orifices in a planar side in the form of plural sprays directed onto adjacent portions of a coil carrying evaporating refrigerant. The sprays flow over the coil to effect substantial transfer of heat from the hydraulic fluid to the refrigerant, with the cooled hydraulic fluid being stored in the reservoir prior to being pumped to the hydraulic tool as needed.

Abstract: An active seat suspension control system provides for continuous adjustment of the height of a tractor seat in response to movement of a mass within a vibrometer. The vertical position of the vibrometer mass is coupled to adjust one of a pair of potentiometers in a bridge circuit with the other potentiometer being adjusted by the actual height of the seat. During extreme movement of the tractor, the control system is disabled by an arrangement which includes a pair of limit switches at opposite extremes of vertical movement of the vibrometer mass and a circuit which effectively uncouples a source of pressurized fluid to a hydraulic cylinder coupled to adjust the vertical position of the seat. The control system is coupled through the tractor ignition switch to the tractor power supply so as to be disabled except when the ignition switch is turned on.

Abstract: Circuitry and methods are presented for detecting the presence of a spectrally distributed signal having a known distribution, e.g. spread spectrum, in a strong noise environment. The signal is split into two channels, each filtering a predetermined frequency band within the given spectrum. The channels are tuned and balanced so that they pass differential amounts of signal energy that may be present but provide equalized noise outputs. The channels are alternately coupled to the input of an energy detector which provides a DC component responsive to the difference in the signal levels of interest, while effectively cancelling noise energy components in each channel. In the spread spectrum example the frequency bands are typically selected to the maximum and a null location in a ##EQU1## distribution.

Abstract: In a bidirectional CATV system, terminal devices at individual subscriber locations are arranged in sets, with each terminal device in a set being coupled to an intermediate polling processor which includes means for storing status data as to each of the terminal devices. The head end system polls the intermediate processors for their consolidated reports, with the result that tens of thousands of subscriber locations can be serviced without inordinate delays by a single head end system.

Abstract: A compact and highly reliable proportioning pumping system for supplying a precise and controllable mixture of concentrate and water in a kidney dialysis machine comprises a central body and a pair of oppositely mounted pivotable linkages coupled to the body. A first pivotable linkage is coupled by connecting rods to a water metering piston and a concentrate metering piston respectively, a variable stroke ratio being provided by a signal actuated drive coupled to the linkage mechanism and controlling the relative position of the end of one of the connecting rods. The change of position is advantageously effected so as to maintain a precise proportionality between the flows delivered by each of the pistons throughout their variable stroke lengths. The range of proportioning adjustments can be mechanically limited and alarm conditions can readily be detected.

Abstract: An arrangement for bidirectionally driving a hammer bank shuttle assembly along a linear path in a line printer includes an opposite pair of circular, rotatable elements having an elongated shuttle assembly mounting element and an elongated counterbalancing element extending between the pair of rotatable elements on the opposite sides thereof. Pole pieces and a magnet disposed between and adjacent the shuttle assembly mounting element and the counterbalancing element provide magnetic flux which flows through portions of the opposite elements to attract and maintain the elements in contact with the opposite rotatable elements.

Abstract: A passive system having high volumetric compliance in response to compressions and expansions, such as are present in low frequency acoustic wave energy, employs a saturated vapor-saturated liquid interface thermodynamically stabilized by distributed heat sinks that interact with the acoustic wave energy. The volumetric compliance of a system, such as a loudspeaker enclosure, is significantly increased by utilizing a spatially distributed mass of fine fibers thoroughly wetted by a liquid, to provide thin liquid sheaths on the fibers that are in good thermal interchange with the fibers themselves and also with the vapor molecules in the spaces between the fibers. The liquid preferably has a low heat of vaporization, a high vapor pressure at the ambient temperature and a low rate of pressure change with respect to temperature. The liquid sheaths and fibers serve as high surface area heat sinks having a short thermal transport distance to supply the alternating heat attendant to evaporation and condensation.

Abstract: A flow control device is disclosed which includes a housing having a plate or partition oriented generally transverse to the fluid flow direction. The partition has a central opening and a plurality of flow passages disposed in a circular array about the opening. The device also includes a generally T-shaped elastomeric element having a stem received by the central opening in the partition and a disk-shaped flange projecting transversely from the stem. The flange has a lower, beveled, annular surface overlying the flow passages and defining with the partition a variable flow area. Variations in fluid pressure causes the beveled portion of the flange to deflect accordingly. The flow area is thereby varied so that the flow rate is maintained substantially constant irrespective of pressure variations.

Abstract: In sound generating systems, it has been ascertained that various factors cause spurious, audible emanations when transducers of reasonable size and cost are driven in complex motions characteristic of typical high fidelity audio reproduction. It is shown that phase effects, unidirectional components, and transient (start-stop) effects give rise to such spurious emanations and that these center about the resonant frequency of the transducer. Means are disclosed which significantly improve the clarity of reproduction by minimizing these spurious emanations. In a typical system in which different transducers are used for different frequency ranges, the spurious emanations are reduced by change of amplitude or frequency or both, without affecting transducer performance, to levels at which they are substantially inaudible. Either or both electronic and acoustic techniques may be used for these purposes.

Abstract: A power tong system for engaging or disengaging threaded pipe sections has an annular rotary member that is supported against lateral thrust and include a hinged portion that is pivotable to permit side access to a pipe. The rotary member is rotated about its central axis by a peripheral drive chain engaging the rotary member through a relatively small wrap angle. The free end of the hinged portion and the opposing end of the principal body of the rotary interlock and become more secure in self-centering fashion under the spreading forces that are exerted during operation. Structurally rigid head plates on opposite sides of the rotary member are slidable relative to the housing, and incorporate spaced apart radial bearing slots that guide oppositely disposed heads that engage the pipe with hardened die elements. Twisting moments on the heads are absorbed in the head plates, such that the heads are subjected only to uniform and symmetrical forces.

Abstract: Three-dimensional thick fabrics are made from a laminate of fabric plies by first inserting pointed rods through the laminate to form rows of holes after which needles are reciprocated through the different holes to pull loops of various yarns through the holes. The loops of yarns in adjacent holes are interlocked to hold the plies together. A guide releasably clamped to each yarn controls tension in the yarn while a doffing point is employed to insure that the needle passes through a loop just formed when penetrating the next hole to insure interlock of the loops. Hollow circular objects are formed by winding a length of fabric a selected number of times around a form, following which the pointed rods are used to form holes in the resulting laminate with the needles and yarns being used to form the interlocking loops through the thickness of the laminate.

Abstract: A hot-gas engine the power output of which is regulatable comprises a cylinder defining variable-volume primary and secondary chambers separated by a piston moving in the cylinder, the movement of which piston is transmitted to an external system extracting the mechanical work produced by the engine. The engine has a heater communicating with the primary chamber, a regenerator communicating with the heater and a cooler containing a supply of working gas at the maximum gas pressure occurring during the work cycle. The engine is provided with valves controlled to pass the working gas to, from and between the primary and secondary chambers in sequential steps.

Abstract: Uniform protective coatings are deposited on components with a high strength bond by utilizing a supersonic plasma stream and a transferred arc system of selectively reversible polarity. By maintaining plasma stream velocity at a sufficiently high Mach number, and using stream temperatures and static pressures which establish a shock pattern characteristic that diffuses the arc, the workpiece is made cathodic relative to the plasma gun at predetermined intervals. This creates a sputtering effect in which electrons and atoms are ejected from the workpiece despite the impacting plasma flow and the ambient pressure level. This sputtering action is undertaken to clean the workpiece once it is sufficiently heated and to cause intermingling of molecules of the substrate material with molecules of a deposition powder injected into the plasma flow. This preparatory deposition, together with the clean workpiece surface, enables a subsequent buildup of securely bonded and high uniform material.

Abstract: A bias fabric having parallel, spaced-apart yarns oriented .+-.45.degree. relative to the long axis of the fabric is formed by directing one or more pluralities of the yarns back and forth across the width of the fabric and securing the yarns around pins mounted on movable conveyors at the opposite sides of the fabric. Alternatively, the yarns are mounted on strips of film with the film strips being secured to the opposite conveyors. In one preferred embodiment one or more elongated yarn laying units arranged to supply yarns through apertures along the length thereof are cycled laterally between the opposite conveyors as the conveyors are moved at a controlled speed to form a 2-ply fabric, the yarns being wrapped around pins on the opposite conveyors using an adjustable roller arrangement mounted on the shuttle or a plurality of pin mounting rings the alternate ones of which move in unison so as to engage odd and then even numbered yarns in the yarn array.