Face International Corporation

Other

Allen Engineering Corporation

Richard P Bishop

Samuel A Face, Jr

Bradbury R Face

Clark Davis Boyd

Glenn F Rogers, Jr

Stephen E Clark

J Dewayne Allen

Norvell S Rose, Jr

Darrell L Darrow

Brad Face

Bradley D Goldizen

Methods and apparatus for screeding freshly placed concrete in which the acoustic impedance of the treating equipment is made substantially equal to the acoustic impedance of the concrete slab. Portions of the screed contacting the plastic concrete are matched to an acoustic impedance approximating the acoustic impedance of plastic concrete, promoting the energy transferred to the concrete. The acoustic matching material is fabricated from a material that has an acoustic impedance within 67% to 150% of the acoustic impedance of the concrete being finished. The acoustic matching material has an abrasion resistance of no greater than 150 measured using ASTM Method G-65 where steel is given a rating of 100. The preferred matching material comprises ultra-high molecular weight polyethylene (UHMWPE) plastic.

Acoustically matched method and apparatus for screeding concrete

Pans for power finishing freshly placed concrete in which the acoustic impedance of the treating equipment is made substantially equal to the acoustic impedance of the concrete slab being treated. Preferably, a powered, twin rotor riding trowel is provided with a pair of circular finishing pans that are attached to the conventional rotor blades used later in the finishing process. The pans are characterized by an acoustic impedance approximating the acoustic impedance of plastic concrete, thereby optimizing the energy transferred to the concrete. Preferred pans comprise ultra-high molecular weight polyethylene (UHMWPE) plastic. During troweling, the pans are frictionally revolved over the plastic concrete for finishing the surface without prematurely sealing the uppermost slab surface. Through the disclosed troweling method, a highly stable concrete surface results, and delamination is minimized. Alternative troweling uses pans coated with layered impedance matching material. Alternative equipment includes slip form pavers.

Acoustically matched concrete finishing pans

Methods and apparatus for power finishing freshly placed concrete in which the acoustic impedance of the treating equipment is made substantially equal to the acoustic impedance of the concrete slab being treated. Preferably, a powered, twin rotor riding trowel is provided with a pair of circular finishing pans that are attached to the conventional rotor blades used later in the finishing process. The pans are characterized by an acoustic impedance approximating the acoustic impedance of green concrete, thereby optimizing the energy transferred to the concrete. Preferred pans comprise ultra-high molecular weight polyethylene (UHMWPE) plastic. During troweling, the pans are frictionally revolved over the green concrete for finishing the surface without prematurely sealing the uppermost slab surface. Through the disclosed troweling method, a highly stable concrete surface results, and delamination is minimized. Alternative troweling uses pans coated with layered impedance matching material. Alternative equipment includes slip form machines.

Method and apparatus for acoustically matched slip form concrete application

Methods and apparatus for power finishing freshly placed concrete in which the acoustic impedance of the treating equipment is made substantially equal to the acoustic impedance of the concrete slab being treated. Preferably, a powered, twin rotor riding trowel is provided with a pair of circular finishing pans that are attached to the conventional rotor blades used later in the finishing process. The pans are characterized by an acoustic impedance approximating the acoustic impedance of green concrete, thereby optimizing the energy transferred to the concrete. Preferred pans comprise ultra-high molecular weight polyethylene (UHMWPE) plastic. During troweling, the pans are frictionally revolved over the green concrete for finishing the surface without prematurely sealing the uppermost slab surface. Through the disclosed troweling method, a highly stable concrete surface results, and delamination is minimized. Alternative troweling uses pans coated with layered impedance matching material. Alternative equipment includes slip form pavers.

Acoustic impedance matched concrete finishing

A circuit including a transformer, preferably a laminated piezoelectric transducer, in combination with a positive feedback amplifier circuit, capable of serving: 1) to produce either an audible or ultrasonic signal; or 2) as an energy source capable of driving an auxiliary high voltage device with an initial and continuing low voltage source such as a battery.

Positive feedback resonant transducer circuit

A multi-layered piezoelectric electrical energy transfer device has its input and output sides electrically isolated from each other. As a transformer, the device provides step-down voltage conversion while the output signal preserves the input signal frequency in a broad bandwidth. For telecommunications applications, the transformer can provide impedance matching with transmission lines, which minimizes line losses and echoes that seriously degrade high-speed data transmission. The piezoelectric transformer also provides a uniform voltage transformation ratio (V,/V,) over wide frequency ranges, and is adaptable for simultaneous audio and data signal telecommunications applications requiring wide bandwidth service.

Multi-layer piezoelectric electrical energy transfer device

A method for manufacturing a cofired multi-layer piezoelectric transformer device includes forming first and second green shapes of a sinterable ceramic composition and applying metallization layer therebetween. Upon cofiring, the composite structure comprises first and second electroactive members bonded together by a conductive layer therebetween. External electrodes are applied and the electroactive members are polarized in a thickness direction, between their two major faces. The first and second electroactive members are arranged such that deformation of one electroactive member results in corresponding deformation of the other electroactive member. The device provides substantial transformation ratios in which relatively high power may be transferred in relation to the size of the unit, operability over wide input and output frequency bandwidths, and electrical isolation of the input voltage and current from the output voltage and current.

Method of manufacturing a co-fired flextensional piezoelectric transformer

A liquid-filled acoustic transducer for finishing an exposed surface of a work medium, such as plastic concrete, transmits acoustic energy generated within an enclosed liquid medium, through a transducer housing member, and into the exterior work medium. Acoustic waves are generated by electrically-actuated liquid-immersed piezoelectric elements housed within the device. The efficiency with which acoustic waves are transmitted from the interior of the device to the adjacent work medium is enhanced by providing an intermediate transducer housing member, disposed between the liquid in which the piezoelectric elements are immersed and the work medium, having acoustic impedances at its two major surfaces matching the respective acoustic impedances of the respective interfacing media and a continuous acoustic impedance gradient between those two surfaces.

Acoustic transducer with liquid-immersed, pre-stressed piezoelectric

A laminated multi-layer piezoelectric transformer comprising two elements joined together with a conductive adhesive and having a bead of the conductive adhesive at the point of junction of the two elements on the exterior surface of the laminated multi-layer piezoelectric transformer and a mounting device for use therewith and comprising a conductive base having a first contact, and curvaceous arms extending at generally at right angles from the conductive base about said laminated multi-layer piezoelectric transformer, a portion of said arms contacting said bead and preferably designed to engage the distal ends of the arms of an insulating cap mounted on the opposing side of the laminated multi-layer piezoelectric transformer said cap having a second contact therein. This combination configured for mounting on a circuit board is also described.

Multi-layer piezoelectric transformer mounting device

A contact device for securely and reliably attaching electrical leads to a laminated multi-layer piezoelectric transformer and comprising a pair of conductive lead attachment plates, disposed on opposite sides of the laminated multi-layer piezoelectric transformer, each having first and second surfaces, the first surface having at least one leg extending therefrom to contact the laminated multi-layer piezoelectric transformer at a node and the second surface being sufficient to permit secure and durable attachment of electrical leads thereto. A variety of geometric configurations of the contact device of the present invention suitable or adaptable to a variety of laminated multi-layer piezoelectric transformer geometries are also described. Such a device, useful for the attachment of a laminated multi-layer piezoelectric transformer to a circuit board, is also described.

Fluorescent lamp excitation circuits are provided which use a resonating piezoelectric transformer along with complementary circuit components, to efficiently convert a DC first voltage to a transformer-output AC second voltage. In the preferred embodiment of the invention, A High Displacement Piezoelectric (HDP) transformer achieves sufficiently high voltage output to 'cold fire' a gas discharge lamp. The disclosed circuit may be modified using conventional electrical sub-circuitry to pre-heat the cathodes of the lamp.

Fluorescent lamp excitation circuit having a multi-layer piezoelectric

Circuits for use in ignition systems are disclosed which use a resonating piezoelectric transformer along with complementary circuit components, to efficiently convert a DC first voltage to a transformer-output AC second voltage. In the preferred embodiment of the invention, a High Displacement Piezoelectric (HDP) transformer converts a DC voltage into an AC voltage which is rectified into a DC signal of sufficiently high voltage to create a spark across the spark gap of a spark plug. The transformer circuit may be a 'self resonating' circuit which relies on an initial pulse from turning on the DC power supply to cause the transformer to begin resonating. In a modified circuit the circuit is not 'self resonating' and instead has a phase shift oscillator sub-circuit that provides small pulse signals to start the transformer resonating when the circuit is initially turned on.

Ignition circuit with piezoelectric transformer

A method is disclosed for advantageously modifying the texture or character of a plastic work material by applying acoustic energy at the work material's natural resonant frequency via a transducer assembly including vibrating the transducer assembly in air to determine the natural resonant frequency of the transducer assembly; determining the natural resonant frequency of the work material and the transducer assembly together; subtracting the natural resonant frequency of the transducer assembly from the natural resonant frequency of the work material and the transducer assembly together to determine the natural frequency of the work material; and applying acoustic energy to the work material at the determined natural frequency of the work material. The transducer assembly includes piezoelectric actuators which provide the acoustic energy.

Feedback-responsive piezoelectric vibrating device

A standing wave pump in which a standing compression wave is produced by a pair of diametrically opposing transducers. The vibrating surfaces of the transducers are oscillated at a frequency sufficient to generate a substantially cylindrical compression wave having substantially planar wave fronts between the transducer pair. The length of pump housing is made to be equal to an integer times half the wavelength of the compression wave and the pump housing acts as a resonant cavity having a standing wave pattern set up in it. Waves are simultaneously produced and reflected by the oscillating surface and are superimposed upon one another and travel to the opposing oscillating surface where this process is repeated, substantially multiplying the intensity of the standing compression wave, which provides a stored-energy effect. The high-intensity standing compression wave has pressure nodes and antinodes, whose pressure differential is used to pump a medium through inlets and outlets advantageously located at the nodes and antinodes.

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Fairfax Station, VA, United States of America

Richard P Bishop