For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks...

Highly energetic thermite compounds have potential applications in combustion synthesis of various materials and processes, but they are hard to ignite by conventional means. A new technique for ignition of pure thermite powder in air atmosphere, using localized microwaves, was demonstrated recently. This exothermic zero-oxygen-balanced reaction may occur underwater, but due to the hydrophobic ...

Metallic powders such as thermite are known as efficient fuels also applicable in oxygen-free environments. However, due to their hydrophobicity, they hardly penetrate into water. This paper presents an effect that enables the insertion and confinement of hydrophobic metallic powders in water, based on encapsulating an air bubble surrounded by a hydrophobic metallic shell. This effect, regarded...

Recent years witnessed an increasing requirement of marine missions like oceanographic investigation, environmental monitoring, underwater structure inspection and sea bottom resource exploitation, which urged the R&D of high performance underwater acoustic (UWA) modems. However, as underwater acoustic channels pose multiple difficulties such as multipath, time-space selectivity, frequency depe...

Underwater sensor network (UWSN) has emerged as a powerful technique for aquatic applications. Different from ground based networks, UWSN features long propagation delay, low bandwidth and high error rate. Limited power capacity and node mobility also make it difficult to apply existing protocols or algorithm designed for terrestrial networks to UWSN. It requires new research at every layer of ...

Advances in low-power electronics design and wireless communication have enabled the development of low cost, low power micro-sensor nodes. These sensor nodes are capable of sensing, processing and forwarding which have many applications such as underwater networks. In underwater wireless sensor networks (UWSNs) applications, sensors which are placed in underwater environments and predicted ena...

Statistical evaluation of the passive structure for the vessel detection is considered. The passive detection structure is based on the statistical likelihood ratio test and on the Neyman-Pearson statistical criterion. The assumption is that a vessel is approximately so-called noisy vessel. It means that the underwater acoustic vessel noise is approximately a stationary ergodic stochastic zero ...

In this paper, we study time-optimal trajectories for fully actuated planar underwater vehicles, with constraints on input forces. Using the Maximum Principle, we focus on the structure of singular extremals and their possible optimality.

The development of two new classes of commercial underwater robotic vehicles – deep diving work-class remotely operated vehicles and survey-class autonomous vehicles – is being driven by the needs of deep water oil production and deep ocean telecommunication cable operations. This paper presents a survey of the present state and future directions of commercial underwater robotics, examines prin...