Abstract: An acoustical transmitting system and method for producing a narrow beam of acoustic energy over a broadband operating frequency range utilizes a parabolic reflector dish, a horn-loaded compression driver for directing acoustic energy toward the dish's reflecting surface, and a low frequency driver mounted behind a central aperture in the dish for producing acoustic energy that combines and interacts with the reflected acoustic energy produced by the horn-loaded compression driver. An input signal processing circuit is provided to condition the audio signal to the horn-loaded compression driver and the low frequency driver to achieve on-axis gain and off-axis cancellations at low frequencies. The addition of the low frequency driver to the reflector dish system effectively extends the ability of the system to produce and transmit acoustic energy in a narrow distribution pattern at frequencies below 1000 Hz using a four foot diameter dish.

Abstract: A screen deck for a vibrating screen apparatus is provided with a plurality of removable and interchangeable modular screen panels, including wire screen panels having pre-crimped screen wires pretensioned in both directions. The invention contemplates the use of interchangeable wire screen panels alone or in combination with polyurethane or rubber screen panels, and provides a screen deck that can be serviced relatively easily at relatively low cost.

Abstract: A method and correction circuit for improving and controlling the listening window and response of a two-way loudspeaker system utilizing a horn-loaded high frequency driver. The correction circuit includes adjustable active all-pass and band-pass filters, in a specific arrangement, coupled with conventional cross-over filters to achieve a maximally flat amplitude and phase response acoustically throughout a preferred listening window. A spectrum analyzer measures the near-field responses of the individual and combined transducers while adjustments are made. A phase shifting circuit is included in the low frequency channel which results in improved near-field to far-field response consistency and significantly improves the subjective characteristics of the high frequency horn.

Abstract: A horizontal impact crusher having a frame cover for accessing the machine's crushing chamber is provided with hydraulic cover latches for opening and closing the frame cover.

Abstract: A puzzle has a transparent top layer and a bottom layer which can be seen through the top layer. The top layer of the puzzle is provided with a top image and the bottom layer with a bottom image which is associated with this top image. When viewed through the transparent top layer both top and bottom images are seen as a composite image. At least one of the top and bottom layers include a plurality of image elements moveable relative to each other to produce at least one desired composite image which is the solution to the puzzle. For added complexity, both top and bottom layers may include moveable image elements which are manipulated from opposite sides of the puzzle. The puzzle is particularly adapted to slide puzzles having two layers of slide tiles.

Abstract: A waveguide seal assembly for a waveguide joint is fabricated in separate parts, including a relatively small inner conductive part for surrounding the coupled waveguide openings in the joined waveguide flanges of two joined waveguide sections, an outer conductive part having a central opening which permits the outer part to fit over the inner part such that an intermediate gap is formed between the inner and outer parts, and a gas sealing element, suitably in the form of an O-ring, fitted into this intermediatex gap. Preferably, an O-ring groove is provided on the outer perimeter of the inner conductive part for retaining the O-ring when the seal assembly is installed. Also, preferably the inner conductive part is slightly thicker than the outer part to ensure good electrical contact at the coupled waveguide openings.

Abstract: A skin test applicator has a applicator handle (21) and separately storable test elements (13). A complimentary snap-fit attachment structure (33, 43) is provided on the applicator handle and test elements to permit the applicator handle to operatively pick up and releasably hold one or more test elements from a suitable sterile storage tray. In one version of the invention, pressure heads (15) are arranged in staggered relation on the test elements to provide maximum spacing between test heads. The skin test applicator reduces storage requirements and the amount of refuse that must be discarded immediately following the administration of a skin test for the diagnosis of an allergic response or other diagnostic test.

Abstract: A self-tapping sleeve for providing a ceiling junction for a suspended lighting fixture has a cylindrical body, a center passageway for containing the junction, a thread structure on the perimeter surface of the cylindrical body, and two perimeter cutting elements at the top end of the cylindrical body for producing a circular cutting action in front of the sleeve when the sleeve is rotated in and advance rotation. A trim ring is additionally provided at the bottom end of the body to trim out the ceiling junction when the sleeve is installed. A key-shaped portion of the center passageway receives the key-shaped end of a drive tool used to install the sleeve.

Abstract: A button contact and array of button contacts are provided for surface mounting a leadless IC device to a circuit board. The button contacts of the button contact array have a substantially flat body lying in a plane and oppositedly directed contact points protruding from resiliently deflectable contact support arms of said body. The button contacts of the invention, which provide a low profile contact between surface mounted components, are suitable for high frequency applications, and particularly high frequency test and burn-in applications, and are relatively durable.

Abstract: A bass reflex loud speaker system for use in high power applications which includes an enclosure with at least two, and preferably three, cone drivers mounted in front of separate and acoustically isolated bass reflex chambers. Each bass reflex chamber is tuned to a separate octave such that the bass reflex modules formed by each bass reflex chamber and its associate cone driver produces a complex acoustical signal comprised of different frequency components in the low frequency range at high sound pressure levels, but with minimum driver cone excursion and distortion.

Abstract: A stand-off device for yieldingly supporting a tree to a tree support stake has an elongated body and an elastomeric cord which extends through the body and which has a tie end extending from the body's distal end so that can be tied to the trunk of a tree either directly, or by means of an intermediate tree tie. By attaching the stand-off device to a tree support stake, a tree can be held upright at the end of the device win a windless condition, yet being allowed to sway in the wind so that the growth and health of the tree will be stimulated.

Abstract: An apparatus and method for cleaning containers, such as sample containers for environmental testing, involves providing fluidly isolated modular cleaning bays which are interchangeably cascaded together for processing trays of containers through different washing and rinsing solutions. In each modular bay a bank of nozzle elements is cycled to traverse into and out of the tray of containers to clean the interior surfaces of the containers.