Abstract: This study provides an argument cautioning against the use of adaptive-beamforming (ABF) techniques in conjunction with a known method for estimating the bottom reflection loss from natural marine ambient noise. This application of ABF has been investigated in the past with rather inconsistent results. Furthermore, no formal proof that ABF algorithms do indeed provide an estimate of the bottom reflection loss is available. This study moves from a recent derivation of the relationship between the bottom reflection coefficient and the Fourier transform of the marine-noise spatial coherence function. The circumstances under which the beamforming operation approximates a discrete Fourier transform (DFT) of the spatial coherence function estimated from array data are analyzed. It is shown that, under certain conditions, conventional beamforming is equivalent to directly computing the DFT of the coherence function, as long as some subtle details are properly taken into account. Furthermore, it is shown that ABF cannot be guaranteed, in general, to perform this operation, and therefore provide an estimate of the bottom reflection coefficient. The conclusions are demonstrated on simulated and measured data.

The observational part of the REP14-MED experiment was conducted in June 2014 in the Sardo-Balearic Basin west of Sardinia (western Mediterranean Sea). Two research vessels collected high-resolution oceanographic data by means of hydrographic casts, towed systems, and underway measurements. In addition, a vast amount of data was provided by a fleet of 11 ocean gliders, time series were available from moored instruments, and information on Lagrangian flow patterns was obtained from surface drifters and one profiling float. The spatial resolution of the observations encompasses a spectrum over 4 orders of magnitude from 𝒪(10¹ m) to 𝒪(10⁵ m), and the time series from the moored instruments cover a spectral range of 5 orders from 𝒪(10¹ s) to 𝒪(10⁶ s). The objective of this article is to provide an overview of the huge data set which has been utilised by various studies, focusing on (i) water masses and circulation, (ii) operational forecasting, (iii) data assimilation, (iv) variability of the ocean, and (v) new payloads for gliders.

Abstract: In this paper a 1:4.25 ratio ferrite magnet and NdFeB magnet flux-focusing magnetic gearbox with a high pole count is analyzed. A simple parameter sweep analysis is used to show that higher than previously published torque density values are achievable. Experimental results are then presented for the NdFeB design that confirm the calculations and also demonstrate that the proposed magnetic gearbox can operate with a low torque ripple.

Several potential avenues exist for redefining the frontiers of computing through nontraditional paradigms. Although none of these paradigms is currently competitive with CMOS-based technology, they have the potential for cheaper, faster, more robust, and more energy-efficient information processing.

Although George Ioup did not use ocean gliders for passive acoustic monitoring, he recognized their value as platforms for PAM and encouraged others to use them. They function well as PAM platforms because (1) they move slowly, minimizing flow noise; (2) they have no propeller or continuously running machinery, minimizing motor noise; (3) they collect acoustic data nearly continuously; (4) they traverse the upper water column every few hours, measuring temperature and salinity as needed for calculating sound speed profiles and enabling accurate modeling of long-range acoustic propagation; (5) they can cover hundreds to thousands of kilometers in distance during a deployment, enabling them to monitor a large area and/or repeatedly monitor a smaller area; and (6) some models can dive to 1000 m, the depth at which some deep-diving cetaceans—sperm and beaked whales, frequent targets of PAM operations—forage and vocalize. Two models of gliders equipped with passive acoustic recording systems were deployed in the Northern Gulf of Mexico in the summers of 2015 and 2017 to study cetacean occurrence and behavior. Here, we summarize the virtues and hazards of glider PAM, and describe acoustic detection and classification of cetaceans in these recordings. [Research supported by GoMRI.]

In this paper an axial flux magnetic gear (AFMG) is proposed that has an integrated outer stator. This axial flux magnetically geared motor (AFMGM) is unique in that the stator shares the high-speed rotor with the AFMG, so there is no need for a separate rotor. The high speed and low speed rotors use a flux-focusing typology. The stator is mounted outside the AFMG and this makes the design mechanically less complex. It also enables the stator to be cooled more easily.