Design Method for Contra-Rotating Propellers for High-Speed Crafts: Revising the Original Lerbs Theory in a Modern Perspective

The main theoretical and numerical aspects of a design method for optimum contrar-rotating (CR) propellers for fast marine crafts are presented. We propose a reformulated version of a well-known design theory for contra-rotating propellers, by taking advantage of a new fully numerical algorithm for the calculation of the mutually induced velocities and introducing new features such as numerical lifting surface corrections, use of an integrated modern cavitation/strength criteria, a modified method to consider different numbers of blades among the two propellers, and to allow for an unloading function in the search for the optimal circulation distribution. The paper first introduces the main theoretical principles of the new methods and then discusses the influence of the main design parameters on an emblematic example of application in the case of counter rotating propellers for a pod propulsor designed for fast planing crafts (35 knots and above)

Design and Implementation of HDL Modules and Circuits for Underwater Optical Wireless Communication

Underwater wireless optical communication has been used for establish a link between mobile vehicles and/or fixed nodes because light, especially in the blue/green region, allows to achieve higher data-rate than acoustical or electromagnetic waves for moderate distances. The here proposed work has the aim to pave the way for diffuse optical communication allowing to support optical communication in an Underwater Wireless Sensor Network of dense-deployed fixed nodes for specific application, such as monitoring and surveillance, for shallow, coastal and inland water in the case of moderate/limited area. The use of light impulse for communication is motivated by the possibility of targeting high data-rate, low-cost and small dimension components. This paper describes an overall vision of the system: a HDL implementation of flexible modules for the management of optical communication (based on IEEE 802.15.4 and IEEE 802.11 standard) which target the interface with current terrestrial technology for Wireless Sensor Networks; the design and implementation of circuits for underwater optical point-to-point and planar communication. The preliminary results and design consideration are reported considering also future possible developments

Optical Wireless Communication for Underwater Wireless Sensor Networks: Hardware Modules and Circuits Design and Implementation

Underwater wireless optical communication has been used for establish a link between mobile vehicles and/or fixed nodes because light, especially in the blue/green region, allows to achieve higher data-rate than acoustical or electromagnetic waves for moderate distances. The here proposed work has the aim to pave the way for diffuse optical communication allowing to support optical communication in an Underwater Wireless Sensor Network of dense-deployed fixed nodes for specific application, such as monitoring and surveillance, for shallow, coastal and inland water in the case of moderate/limited area. In particular our research explores the possibility of targeting the interface with current available terrestrial technologies. The use of light impulse for communication is motivated by the possibility of targeting high data-rate, low-cost and small dimension components. This paper describes an overall vision of the system: a HDL implementation of flexible modules for the management of optical communication (based on IEEE 802.15.4 and IEEE 802.11 standard) which target the interface with current terrestrial technology for Wireless Sensor Networks; the design and implementation of circuits for underwater optical point-to-point and planar communication. The preliminary results and design consideration are reported considering also future possible developments

VHDL Modeling of PHY and MAC Layer Modules for Underwater Optical Wireless Communication

In this paper the description of hardware modules for managing underwater wireless optical communication is proposed. The modules have been developed for testing purposes considering previous released protocols for optical wireless communication (i.e. IEEE 802.11-IR) and the characteristics of underwater medium and taking into account the possible integration with current technologies for terrestrial Wireless Sensor Network (WSNs). The here proposed work is a first step to pave the way for diffuse optical communication allowing to support optical communication in an Underwater Wireless Sensor Network (UWSN) of dense-deployed fixed nodes which could be used for different specific application, such as monitoring and surveillance, for shallow, coastal and inland water in the case of moderate/limited area. This paper describes in particular the design and the implementation of the PHY and MAC Layer described in an HDL language and implemented on Field Programmable Gate Array (a low cost, low power Actel IGLOO FPGA) along with a brief description of the circuits implemented to support the generation and reception of light impulse

Smart Plankton: a new generation of underwater wireless sensor networks

The aquatic world, which covers more than the 70% of the earth, has been largely unaffected by the WSN revolution (ignited by DARPA funded UC Berkeley \u201cSmart Dust\u201d project) due to the difficulty of transferring most of the knowhow, developed for terrestrial and aerial systems and devices, to their underwater counterparts. Nowadays underwater wireless networks are expensive (US$ 10k or more), sparsely deployed (a few nodes, placed kilometers apart), typically communicating directly to a base-station or sometimes based on the use of underwater manned or unmanned vehicles. Our research is aimed to develop a new generation of UWSN (Underwater Wireless Sensor Network), called Smart Plankton, by getting inspiration from marine biology and aquatic micro-organism such as zooplankton and phytoplankton. Our target is to develop a self-organizing network composed by a relatively large number of innovative nodes, equipped with sensors for monitoring, surveillance, underwater control and many others potential applications

Smart Plankton: a nature inspired Underwater Wireless Sensor Network

In the last years with the flourishing of the WSN (wireless sensor network) paradigm, ignited by DARPA funded UC Berkeley "Smart Dust" project, the monitoring and exploration of the terrestrial enviroment has greatly improved. The acquatic world, which covers more than the 70% of the earth, instead, has been largely unaffected by the WSN revolution due to the difficulty of transferring most of the know-how developed for terrestrial and aerial systems and devices to their underwater counterparts. The aim of this article is to propose a new generation of UWSN (underwater wireless sensor network), called Smart Plankton, by drawing inspiration from marine biology and acquatic micro-organisms. Our focus is on network node individual body, communication link among devices, energy scavenging and production and swarm intelligence