Abstract: A tension sensor includes a planar tab having a first and second side, first and second end sections and an aperture through each of the end sections. A first strain gage is attached to the first side of the tab. The first strain gage has a tension grid aligned to a longitudinal axis of the tab and a cross-tension grid perpendicular to the tension grid. A second strain gage is attached to the second side of the tab. The second strain gage has a tension grid aligned to the longitudinal axis of the tab and a cross-tension grid perpendicular to the tension grid. The first strain gage and second strain gage are wired in a Wheatstone bridge in which the tension grid and the cross-tension grid of the first strain gage form one side and the tension grid and the cross-tension grid of the second strain gage form another side.

Abstract: A cable tray and method of use is provided with the cable tray having a bottom extending along a horizontal panel with two opposite side edges. A pair of side walls attaches to the two opposite side edges. A first positioning rack extends between the side walls. The first positioning rack is orthogonal to the tray bottom and the side walls. A second positioning rack extends between the side walls. The second positioning rack is orthogonal to the tray bottom and the side walls. A first foot bar affixes to an underside of the tray bottom. The first foot bar is vertically aligns with the first positioning rack. A second foot bar affixes to the underside of the tray bottom. The second foot bar vertically aligns with the second positioning rack. Each of the first positioning rack and second positioning rack includes cable support apertures.

Abstract: A strength member sewing machine is provided which comprises upper and lower feeder spools, a collection spool and idlers positioned on a support structure. A cord supply, a fabric shaper, a speed control and a pressure foot lift are positioned on the structure. Fabric from the spools is kept in tension with the idlers while moving toward the fabric shaper. The fabric from the upper spool is crimped while the fabric from the lower spool remains flat underneath the shaper. Between the fabric layers, pull cords are pulled through from the cord supply thru the fabric shaper. The fabric with crimps and with the pull cords inside the crimps is sewn to the fabric from the lower spool to create casings with a pull cord in the internal space of each casing. The joined fabrics with the pull cords are collected by the collection spool as a finished product.

Abstract: A method is disclosed for calibration of a towed line array. In a low frequency band, calibration is performed using an acoustic field observed by reference standard hydrophones. The observations form a model of a complex acoustic field throughout a space occupied by a measurement apparatus. The array sensitivities are computed by comparing output voltages of the array with the acoustic field estimated at the locations occupied by hydrophones of the array. Variations in the acoustic field that cannot be accounted for by free field propagation theory are included in the calculation of array channel sensitivities. The method extends the low frequency limit for the calibration to less than the minimum frequency at which free field propagation conditions can be approximated. Boundary reflections and spatial variations in the acoustic field are recognized. The spatial distribution of acoustic energy is used to provide low frequency calibration with improved precision.

Abstract: An inflatable launch and recovery system for a towed body is provided. The system is containerized for ease of transport. A container houses a tow body, tow cable, a winch, winch controls, an inflatable ramp, deployment and retrieval equipment, power junctions and air line connections. Inflatable arch shaped tubes and spacer fabric form the ramp structure from which the tow body can be launched and recovered. The ramp can be ballasted to provide hydrodynamic stability and to provide sufficient system depth to accommodate retrieval of towed bodies operating below a liquid medium surface. Additional control can be achieved using inflatable or rigid fin elements or downward lifting surfaces. A rigid clamping fixture connects the ramp structure to the vessel. A snubber element dampens vibrations and transient tow loads.

Abstract: A method is disclosed for calibration of a towed line array. In a low frequency band, calibration is performed using an acoustic field observed by reference standard hydrophones. The observations form a model of a complex acoustic field throughout a space occupied by a measurement apparatus. The array sensitivities are computed by comparing output voltages of the array with the acoustic field estimated at the locations occupied by hydrophones of the array. Variations in the acoustic field that cannot be accounted for by free field propagation theory are included in the calculation of array channel sensitivities. The method extends the low frequency limit for the calibration to less than the minimum frequency at which free field propagation conditions can be approximated. Boundary reflections and spatial variations in the acoustic field are recognized. The spatial distribution of acoustic energy is used to provide low frequency calibration with improved precision.