Abstract This paper introduces a novel ESPRIT-based closed form source localization algorithm applicable to arbitrarily spaced three-dimensional arrays of vector hydrophones, whose locations need not be known. Each vector hydrophone consists of two or three identical but orthogonally oriented velocity hydrophones plus one pressure hydrophone, all spatially co-located in a point-like geometry. A velocity hydrophone measures one Cartesian component of the incident sonar wavefield’s velocity vector, whereas a pressure hydrophone measures the acoustic wavefield’s pressure. Velocity-hydrophone technology is well established in underwater acoustics and a great variety of commercial models have long been available. ESPRIT is realized herein by exploiting the nonspatial interrelations among read more

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Abstract A new type of PVDF hydrophone, the multilayer planar PVDF hydrophone, is described in this paper. The hydrophone disturbs measured acoustic fields very little and has a high sensitivity. The noise equivalent pressure of the hydrophone is 45 dB re 1 μ Pa per Hz  bandwidth.The working freqency range og hyrophon  is 20kHz ~4MHz.In the range of 100kHz ~ 1MH,the hydrophone has a  flat frequency response with sensitivity -205 dB & 1.5 dB (0 dB = 1 V/pPa). In this range, the hydrophone has been used for five years as a standard one. Two other applications (measurements of noise spectra and ultrasonic imaging) are also reported. Download read more

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Abstract The design of a new wideband, quantitative shock wave hydrophone is presented. The sensor not only has a wideband (>SOMHz) and linear (up to 100MPa) response, but it also operates in a measurement environment in which the hydrophone element’s sensitivity changes as a function of shock wave exposure. Thin films of polyvinylidene difluoride (PVDF) were used in a disposable hydrophone configuration. A self-monitoring feature, based on the change in hydrophone electrode resistance as the electrode materials are removed by shock wave action, indicates that the hydrophone element needs to be replaced. Development efforts include: 1) reducing the manufacturing costs; 2) determining the relationship between electrode resistance and hydrophone sensitivity; 3) developing a read more

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Abstract Wireless sensor nodes are autonomous devices incorporating sensing, power, computation, and communication into one system. Applications for large scale networks of these nodes are presented in the context of their impact on the hardware design. The demand for low unit cost and multiyear lifetimes, combined with progress in CMOS and MEMS processing, are driving development of SoC solutions for sensor nodes at the cubic centimeter scale with a minimum number of offchip components. Here, the feasibility of a complete, cubic millimeter scale, single-chip sensor node is explored by examining practical limits on process integration and energetic cost of short-range RF communication. Autonomous cubic millimeter nodes appear within reach, but process complexity and substantial read more

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Abstract Smart Dust particles are small smart materials used for generating weather maps. We investigate the open problem posed by Vidal et al. on the optimal number of Smart Dust particles necessary for constructing,precise.,cost effective and accurate 3-D weather map. Keywords: Smart structures,matching ,optimization Download read more

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