Abstract: An ultrasonic transducer with housing contains a transducer assembly, an outer housing surface being fixed against a barrier surface for transferring ultrasonic waves to and from a barrier. The housing has an inner surface with plateau. A cap closes the housing and the transducer assembly has a piezoelectric transducer with a pressure surface around its outer perimeter and an opposite vibration surface engaging the plateau. A ring engages the pressure surface for biasing the vibration surface against the plateau. A holder engages the cap, transducer and ring for positioning and a plurality of springs are spaced around the transducer perimeter and between the cap and ring for biasing the vibration surface toward or against the raised plateau. A viscous couplant is between the vibration surface and plateau for enhancing transmission of the ultrasonic waves.

Abstract: An apparatus and method for transmitting data and power through a metal barrier using ultrasonic waves, having ultrasonic transmission channels through the barrier formed by coupling ultrasonic transducers on opposite sides of the barrier. A power transmitter sends power over a channel and forward and reverse data transmitters send forward and reverse data signals by orthogonal frequency-division multiplexing OFDM over a separate channel. The data signals are made up of plural sub-carriers at plural different sub-carrier frequencies with none of the sub-carriers of the forward transmission signal being at a power harmonic frequency.

Abstract: Method and apparatus for rotational alignment and attachment of ultrasonic transducers to a barrier with one submerged surface uses a temporary transducer assembly to position mounting rings on opposite surfaces of the barrier. Plural permanent transducers are then mounted to each mounting ring and are aligned with each other across the barrier by virtue of the alignment of their mounting rings. The submerged mounting ring is used like a cylinder in combination with a mounting plate for the transducers on the submerged side of the barrier or each submerged side transducer has a suction cup fitting for use to exclude water from between each transducer and the submerged barrier surface to facilitate bonding of the submerged side transducers to the barrier.

Abstract: Apparatus for communicating information across a solid wall has one or two outside ultrasonic transducers coupled to an outside surface of the wall and connected to a carrier generator for sending an ultrasonic carrier signal into the wall and for receiving an output information signal from the wall. One or two inside ultrasonic transducers are coupled to an inside surface of the wall and one of them introduces the output information signal into the wall. When there are two inside transducers inside the wall, one receives the carrier signal and the second transmits the carrier after it is modulated by the output information from the sensor. When there is one inside transducer, the output information from the sensor is transmitted by changing the reflected or returned signal from the inside transducer. A power harvesting circuit inside the wall harvests power from the carrier signal and uses it to power the sensor.

Abstract: A method and apparatus for determining the degree of dynamic hardness of a material, such as a sporting equipment item. The method includes the steps of impulsively exciting a surface of the material by impacting the surface against a second, relatively hard surface in contact with a force-measuring device, and then measuring a signal from the force-measuring device to determine a frequency-dependent spectrum of the force exerted by the excited surface on the second surface. From this data, a roll-off frequency is measured and then analyzed to determine the degree of dynamic hardness of the material.

Abstract: A method for measuring dynamic hardness of elastic materials is applied particularly to determining the state of tonal quality for a piano hammer. The method includes selecting a piano hammer of predetermined type from a set of piano hammers, causing the selected piano hammer to strike against an impact surface having the form of a piano string or string grouping appropriate to a piano hammer of the predetermined type, measuring one or more elements of force and motion of the piano hammer striking the impact surface, e.g. force, determining, e.g., the cut-off frequency of the power spectrum for the selected piano hammer striking upon the impact surface, and comparing the determined cut-off frequency of the power spectrum for the selected piano hammer against a predetermined range of cut-off frequencies of power spectrum acceptable for piano hammer of the predetermined type. An apparatus for testing is also described.

Abstract: A piano key cover having a body of synthetic material pigmented to resemble natural ivory defines a top playing surface having a random orientation of peak-to-valley texture and a multiplicity of fine pores to replicate a surface of natural ivory. A multiplicity of the pores have diameters generally in the range of 0.0002 to 0.0012 inch (0.005 to 0.030 mm). The synthetic material is selected from the group consisting of acrylic polymer, polyurethane, epoxy and the like. A method for forming such a piano key cover and a piano having key covers of the invention are also described.

Abstract: A method for measuring dynamic hardness of elastic materials is applied particularly to determining the state of tonal quality for a piano hammer. The method includes selecting a piano hammer of predetermined type from a set of piano hammers, causing the selected piano hammer to strike against an impact surface having the form of a piano string or string grouping appropriate to a piano hammer of the predetermined type, measuring one or more elements of force and motion of the piano hammer striking the impact surface, e.g. force, determining, e.g., the cut-off frequency of the power spectrum for the selected piano hammer striking upon the impact surface, and comparing the determined cut-off frequency of the power spectrum for the selected piano hammer against a predetermined range of cut-off frequencies of power spectrum acceptable for piano hammer of the predetermined type. An apparatus for testing is also described.

Abstract: A piano key cover having a body of synthetic material pigmented to resemble natural ivory defines a top playing surface having a random orientation of peak-to-valley texture and a multiplicity of fine pores to replicate a surface of natural ivory. A multiplicity of the pores have diameters generally in the range of 0.0002 to 0.0012 inch (0.005 to 0.030 mm). The synthetic material is selected from the group consisting of acrylic polymer, polyurethane, epoxy and the like. A method for forming such a piano key cover and a piano having key covers of the invention are also described.

Abstract: A piano key cover is formed of synthetic material pigmented to resemble natural ivory and having a top playing surface with a random orientation of peak-to-valley texture and a multiplicity of fine pores replicating natural ivory. The key cover is formed by providing a mold, engraving a surface of the mold with a randomly-oriented pattern of peak-to-valley texture replicating natural ivory, placing in the mold a composition of suitable synthetic material pigmented to resemble natural ivory and filler, the filler having the characteristic of being removable from a molded article by further treatment, forming the piano key cover within the mold, and treating the piano key cover to remove the filler thereby causing the surface of the paino key cover to define a plurality of fine pores replicating the surface of natural ivory. A piano including the key cover of the invention, and formed by the above method, is also described.

Abstract: A periodic structure such as a diffraction grating is disposed on the surface of an object from which acoustic emissions are to be detected. A plane monochromatic light beam is incident on the periodic structure and forms a number of Bragg diffraction orders at predetermined angles. A detector positioned to intercept one of the diffraction orders receives light whose frequency has been Doppler shifted by surface motion on the object. A reference beam, also incident on the detector heterodynes with the Doppler-shifted beam so that the Doppler component can be recovered. In one embodiment, the reference beam is also incident on the surface and itself produces Bragg diffraction orders. The geometry produces up Doppler in the Bragg diffraction orders from one beam and down Doppler from the Bragg diffraction orders from the other beam and selected Bragg diffraction orders from both beams are heterodyned in the detector.

Abstract: The velocity and change in velocity of a rotating or otherwise moving surface is measured by a laser Doppler technique. In particular, a diffraction grating is formed on the moving surface either by machining processes or by affixing a ready-made grating thereto. The grating surface exhibits periodicity in one or more directions, either separately or simultaneously. The presence of the grating produces Bragg order diffraction reflections at specific angles relative to the surface. These Bragg order reflections contain information, in the form of Doppler shifts, concerning the motion of the surface and the body to which it is attached. This Bragg order Doppler shift information is readily analyzable using conventional signal processing apparatus and processes to produce the desired velocity and torsional vibration information.

Abstract: A high velocity carburetor comprises a housing defining an air flow conduit with an air valve member therein. The air valve member includes a curved air-conducting surface facing the air stream and at least one position of the member for establishing a vortex flow. Fuel is supplied through the axial center of rotation of the air valve member to the conduit and into the vortex stream for facilitating atomization of the fuel into the air stream. The valve member is J-shaped or cylindrical. A fuel metering device is provided through the axial center of rotation of the air valve member which includes an axially movable but rotationally fixed inner fuel conduit mated to a rotationally movable but axially fixed outer tube. A cam is provided on the outer tube with a cam follower on the other tube to establish a needle fuel valve or metering fuel to the air conduit. This carburetor can be used in either a power-increasing or a fuel-efficient mode.

Abstract: A technique for reducing noise generated by transverse vibrations in elongated members comprises the application of a friction element on a surface of the member. The friction element is forced against one or more surfaces of the member by a selected normal force and is provided in a vicinity of maximum distortion of the member when the member undergoes vibrations. A differential movement between the inner surface of the friction element and the outer surface of the member causes heat to be generated which dissipates the energy of such transverse vibrations.

Abstract: A device for treating flowing working gases in order to reduce their operational noises and in most instances also to increase their operating efficiency comprises a flowing working gas operating device which has a discharge conduit with at least one discharge opening for the outflow of the working gas. A check valve is associated with the discharge and includes an elastic valve member movable to close the opening when the flow thereof decreases to a predetermined amount for example as determined by the reduction of pressure of the gases so as to prevent any back flow into the conduit which is likely to produce noise.

Abstract: A nozzle seal for restricting pneumatic leakage from the nozzle hole of a pneumatic hammer having a tool shank movable therein, comprising, a bushing member and a retaining member axially aligned in the nozzle hole of the pneumatic hammer with a seal member therebetween. Bores are provided through the bushing member, retainer member and seal member for accepting the tool shank with the seal member having a bore closely fit around the tool shank to prevent a leakage of air from the interior of the hammer through the nozzle hole. The bushing member is press-fit and firmly held in the nozzle hole while the retainer member is slip-fit into the hole to facilitate its removal and access to the seal member. The bores may be polygonal, circular or oval to accept tool shanks of corresponding cross-sectional shapes.

Abstract: A muffler construction, particularly for exhaust gases of air-operated tools, comprises, a tubular sleeve having a passage therethrough, an exhaust gas pipe connected into the sleeve and defining a constricted flow passage with the sleeve, first and second opposed cylindrical coaxial shell sections, each having a closed end wall at their respective outer ends and facing in opposite directions engaged with the exhaust gas pipe, and sidewalls spaced radially outwardly from the sleeve. The exhaust gas pipe has a gas pipe discharge and there are partition walls in the shell sections defining a first expansion chamber and at least one additional expansion chamber. A constricted flow passage is defined between the first expansion chamber and the at least one additional expansion chamber with sealing and enclosing members closing the sidewalls of the first and second shell sections so as to define the first expansion chamber and at least one additional expansion chamber within the shell sections.

Abstract: Sudden changes in arc current are slowed to mitigate the resulting noise. A sensor detects large decreases in current during initial stages of arc quench and actuate circuits to maintain ionization and current flow to avoid sharp final drop that causes loud noise impulse. Ionization can be maintained by supplying RF energy at appropriate frequency to the arc electrodes and/or by increasing the arc voltage. The sophisticated control algorithm is implemented utilizing an inexpensive microprocessor to exert proper control of arc sustaining parameters to mitigate arc quenching impulse noise.

Abstract: A reduced operating noise nozzle for a cutting device using at least one electrode and an electric arc to cut material of a workpiece, comprises, a nose end piece disposed around the electrode which has an outer surface tapered from an outer relatively wide diameter end inwardly toward a smaller diameter end which faces the workpiece to be cut. Compressed air is directed in a substantially annular flow path along the tapered surface of the nose piece from the wide diameter end toward the smaller diameter end thereof. Noise which would have emanated from the nozzle, especially when the material of the workpiece which is melted by the arc is blown away to effect the cutting operation, will be greatly reduced.

Abstract: A muffler construction, particularly for exhaust gases of air-operated tools, comprises, a tubular sleeve having a passage therethrough, an exhaust gas pipe connected into the sleeve and defining a restricted flow passage with the sleeve, first and second opposed cylindrical coaxial shell sections, each having a closed end wall at their respective outer ends and facing in opposite directions engaged with the exhaust gas pipe, and sidewalls spaced radially outwardly from the sleeve. The exhaust gas pipe has a gas pipe discharge and there are partition walls in the shell sections defining a first expansion chamber and at least one additional expansion chamber. A constricted flow passage is defined between the first expansion chamber and the at least one additional expansion chamber with sealing and enclosing members closing the sidewalls of the first and second shell sections so as to define the first expansion chamber and at least one additional expansion chamber within the shell sections.