Abstract: Modified configurations for electrical connectors to ceramic transducers are designed to reduce failure rates due to fatigue during transducer operation. These modifications eliminate or reduce one or both of the problems causing the fatigue, tensile forces acting on electrical wires connected to ceramic electrodes and unreliable solder joints. Star and pin configurations of wire soldered to ceramic transducers control the position of the wires, thus reducing the tensile forces on the wire. Plug connectors use pressure contacts between the ceramics, eliminating the need for solder joints.

Abstract: Disclosed is an object-oriented approach to storage and transmission of retrievable items in a client-server computer environment. Special processing modules manage retrieval and permanent storage, on client computers, of requested objects in a manner that minimizes unnecessary transmission and storage. The user enters a "subscription" in connection with items related to hierarchically inferior items. The subscription specifies the amount of information the user desires to download and store locally with respect to a specified hierarchical depth level. The invention also includes a pruning module for deleting, from local storage, items inconsistent with the subscription and which the user does not explicitly indicate a desire to store, and a facility for updating locally stored items upon re-establishment of communication with the server.

Abstract: A preamplifier for beamforming hydrophone signals of a sonar array. The invention uses an amplifier that provides a current-source type of output for driving the beamforming network, thus avoiding the substantial signal loss inherent in using voltage-source amplification. To obtain the stability of gain required in this type of operation, the invention employs a negative feedback system that can be easily adjusted by choice of resistors to accommodate desired levels of shading and signal equalization. The advantages provided are savings in cost, reduction in size and power requirements and improved in signal-to-noise ratio.

Abstract: A noise trap circuit particularly suitable for use in an electro-acoustic system, operates to suppress low level signals or noise while allowing a relatively large signal to pass unattenuated between input and output terminals of the circuit. Blocking elements between the input and output terminals establish a high impedance path to the noise but switch to a conductive state when the large signals are present at the input terminals. Shunt elements across the output terminals provide a low resistance path or "crowbar" when only the noise is present at the input terminals, but switch to a non-conductive state when the large signals are sensed at the circuit input.