Abstract: Signalling apparatus in which a sensed change in condition, e.g. a window opened by an intruder or a valuable art object moved, causes the free end of a cantilevered spring to be snapped or twanged. A piezoelectric film bonded to the spring generates a pulsating voltage which energizes a transmitter, independently of any external power source. Remotely, a receiver which is selectively responsive to the transmitted pulsating signal generates an output signal indicating the change in condition, e.g. for initiating an alarm.

Abstract: The partition system disclosed herein incorporates apparatus for generating a speech masking acoustic field. Respective speakers are mounted near the bottom of each of a plurality of partition panel segments defining each work space and are aimed horizontally. These speakers are driven by respective signals which are subjectively incoherent as to frequencies of interest in the masking spectrum, thereby to provide a sound field without perceptible discontinuities.

Abstract: A low noise, axial flow fan particularly suited for use in a turbulent air flow such as the flow exiting an automobile radiator has a band that is secured to the outer ends of the fan blades. The blades are highly forwardly skewed and have an increasing blade angle as a function of blade radius over at least the outer portions of the blade. Each blade is secured to the band along its full width. In the preferred form, the band has a cross-sectional shape that acts as a nozzle to accelerate the airflow through the fan, each blade has a cambered, airfoil cross-section, and the entire fan is formed of an injection molded plastic as a single, integral structure.

Abstract: This disclosure deals with measuring either discontinuous or continuous impedance transitions in various media to identify or delineate the properties and nature thereof by transmitting radiant energy waves to such media to produce reflected waves therefrom, deconvoluting the outgoing and returning waves, and integrating the resulting reflection impulse-response function so as to enable appropriate interpretation of the resulting display for identification and related purposes.

Abstract: Computer apparatus which employs a plurality of processing units, a memory unit, and a communication unit, each of the units including a data transfer bus. A bus coupler is provided between each pair of units of differing type to form a distributed data communications network. An addressable, passive task register is associated with one of the units for communication through the couplers and is adapted to register a task priority value associated with a task request, the register being readable by any one of the processor units to obtain the highest priority value registry.

Abstract: The three-dimensional display system disclosed herein employs the varying focal properties of a vibrating mirror to cause sequentially generated image components to appear juxtaposed in space. The mirror is constructed as a circular reflective plate having substantial stiffness and resilience. The plate is weighted about its rim and is supported by a flexible support ring engaging the plate along a concentric circular locus spaced inside of the rim so as to provide a useful curvature over substantially the entire surface of the plate.

Abstract: In the frequency measuring system disclosed herein, a control signal is generated which is related to the value of function of the input signal for a selectable delay time. The average value of the control signal is employed to control the clock rate of a shift register which is used to obtain a delayed version of the input signal, the input signal being digitized and fed into the shift register. This feedback path forms a servo-loop which adjusts the clocking rate of the shift register in correspondence with the frequency of any coherent component in the input signal, even though the input signal may be a composite comprising many random components.

Abstract: Acoustic impedance transitions in human or animal bodies or other media are measured for identification and diagnostic purposes by exposing the body to acoustic energy pulses to produce echo pulses which are detected. The echo pulses are processed to indicate the relative specific acoustic impedance of the exposed body as a function of the time/distance relationship of the echo pulses relative to the medium, thereby to enable the determination of the relative extent and position of irregularities in the body, for example.

Abstract: The invention involves the use of a plurality of incoherent noise generators distributed, in one embodiment, along ceilings in open-plan and partitioned office spaces and the like, to diffuse masking sound energy through acoustical tile and other false ceiling structures while tailoring the same for speech privacy results, by providing a uniform, delocalized and incoherent masking sound space.

Abstract: The error-checking scheme disclosed herein is adapted for use in digital data processing systems, e.g. computers, in which binary data is variously transmitted and/or stored and in which the data source or destination is designated by a binary address. In a preferred embodiment, the data is divided into two fields and a respective parity bit is generated corresponding to each data field. Each data parity bit is then combined with a parity bit corresponding to the binary address to yield a respective combinational parity bit. Each of the resultant combinational parity bits is then sourced with the respective data field. Accordingly, a system sub-component receiving the sourced data with the combinational parity bits can detect any type of single error occurring in either the address or the data.

Abstract: This disclosure is concerned with novel rotor blade and similar foil designs that, by critical skewing of intermediate blade regions where the airflow is supersonic, prevents leading edge shocks and shock-related noise.

Abstract: This disclosure is concerned with reducing blade-generated cavitation and accompanying noise in systems such as marine ducted reversible thrusters and the like, by novel techniques including a skew-forward blade configuration at the outer radii and particular blade thickness/chord length ratios associated therewith.

Abstract: This disclosure deals with a novel closure seal embodying the compression of a region of a tubular member adjacent a door mounting edge during closure of the door, to pump air into a communicating region of the member disposed along the bottom edge of the door, to expand the same into a seal upon total closure of the door.

Abstract: The present disclosure deals with ultrasonically selectively dissolving solid and semi-solid unwanted materials, such as vitreous gels, membranes, cataracts and similar materials in ophthalmic operation applications, for example, by radiating from a physically small source, high-frequency, preferably pulsed, acoustic waves, while positioning the material to be selectively locally dissolved by such waves at a selected region sometimes in contact with or near-contact or within a short distance from the source of the order of a millimeter or so, at which the propagated acoustic wave energy can effect such phenomena as, for example, localized cytolysis of the material at the selected region thereof substantially normal to the wavefront of the radiated acoustic wave region, and without substantial damage to the portions of the material external to said selected region, and with adjustment to obviate any substantial temperature rise at the material.