Underwater

: China is strengthening diplomatic ties and building naval bases along the sea lanes from the Middle East. This "String of Pearls" strategy is designed to protect its energy security, negate US influence in the region, and project power overseas. China is rapidly building a blue-water navy, developing advanced missile technology, and stockpiling undersea mines to counter US Navy capabilities, especially in the event of a conflict over Taiwan. To counter China's growing naval power, the United States can exploit a critical vulnerability China's dependence on sea lines of communication. Eighty percent of China's oil imports pass through the Strait of Malacca; the Chinese leadership calls this strategic weakness the "Malacca Dilemma." In conjunction with naval forces, land-based airpower offers a promising way to control key maritime checkpoints and trade routes. Land-based airpower proved a decisive maritime force in the war against Japanese shipping d...

A dichotomy between depth penetration and resolution as a function of sonar frequency, draw resolution, and beam spread challenges fish target classification from sonar. Moving high-frequency sources to depth using autonomous underwater vehicles (AUVs) mitigates this and also co-locates transducers with other AUV-mounted short-range sensors to allow a holistic approach to ecological surveys. This widely available tool with a pedigree for bottom mapping is not commonly applied to fish reconnaissance and requires the development of an interpretation of pelagic reflective features, revisitation of count methods, image-processing rather than wave-form recognition for automation, and an understanding of bias. In a series of AUV mission test cases, side-scan sonar (600 and 900 kHz) returns often resolved individual school members, spacing, size, behavior, and (infrequently) species from anatomical features and could be intuitively classified by ecologists — but also produced artifacts. Fi...

These underwater radiated noise and vibration measurements were conducted on a full-scale ship in August 2000. During the trails it was found that several spike noises are dominant. To find the location oj high vibration level places and its frequencies, and the machines, which generated high level point noise components, 4 accelerometers were fixed in the engine and auxiliary rooms .We were using this system to find the relationship between certain manoeuvres and the vibratlon level caused by them. Propellers and engines are usually the major sources of noise in ships but gearboxes can also be significant contributors. The way of mounting of the machines and the resulting vibration oj the hull are determining issues in the radiation ot underwater noise. Naval Test and Evaluation Acoustic Ranges contain an accurate radiated noise measurement system consisting of a bottom-mounted hydrophone array for sailing condition and a stationary range. The sophisticated digital narrow-band inst...

This report documents a study performed for the U.S. Army Engineer District, Seattle to identify and evaluate feasible methods for reducing annual maintenance dredging in the outer Federal navigation channel at Grays Harbor, WA, by modification of the north jetty. Main interest was in potential reduction of southward sand bypassing the north jetty and preservation of the jetty should the neighboring beach erode. Considerable information and predictive capability were generated concerning the behavior of the Federal navigation channel and adjacent coastal and inlet shorelines. The study was conducted as a coordinated multi-disciplinary approach involving field measurement, physical modeling of the hydrodynamics and potential sediment pathways, geomorphic analysis and sediment budget formulation, and numerical modeling of waves, circulation and sediment transport, including modeling of shoreline change and bypassing. Numerous alternatives were considered and subjected to a screening p...

As an acoustic communications medium, water is characterized by frequency dependent attenuation, short range, very low bandwidth, scattering, and multi-path. It is generally difficult to acoustically communicate even terse messages underwater much less images. For the naval mine countermeasures mission, there is value in transmitting images, if possible. The contribution of this paper is a methodology to encode, compress and transmit small (100s of kB) side-scan sonar images underwater with micromodems. The work has been validated through several at-sea trials. The reconstruction of the received images is of a fidelity that operators can visually recognize targets they normally look for in these images. Keywordsunderwater communications, transmission of sonar images underwater, image compression, image encoding

The variety, availability, sales and use of dietary supplements (DS) remain poorly understood by the mainstream medical community, but the potential for use and abuse of DS cannot be taken lightly by undersea medical officers (UMO). Despite the indisputable pharmacologic effects many of these over-the-counter (OTC) products exert, the use of DS is generally overlooked by clinicians. DS information is not covered in much depth, if at all, in medical education, and physicians are not trained in this area. As such, many may feel uncomfortable with their lack of familiarity regarding the ever-increasing supplement pharmacopoeia. Peer-reviewed scientific research and evidenced-based information are often limited. Moreover, because the general public and active duty community perceive these natural substances as harmless, the products often do not come to the attention of physicians at all. Less than half of all users of DS consult a physician or a practitioner about alternative products ...

Portable underwater electrical power is needed for many commercial, recreational and military applications. A battery system is currently not available to meet these needs, which was the aim of this project. Lithium-ion battery cells (Panasonic (CGR18650E)) were chosen, based on their high energy density and availability. To increase their voltage, 8 battery cells were connected in series (“sticks”) and protected

'City of waters', Venice represents a unique example of the challenges to be met in order to reconcile the conflicting demands of heritage preservation, infrastructural development and environmental management. This paper expands on the strategic value of Archaeological Impact Assessments (AIA) – studies initiated in response to development proposals that will potentially disturb or alter archaeological sites – by presenting a case study related to an AIA undertaken in Venice prior to the construction of a pipeline stretching across the central and south parts of its lagoon (Fusina Integrated Project). The morphology of this area is very complex and diverse, and it is characterised by the presence of numerous canals, shallows and shoals, a landscape (or, rather, a waterscape) shaped by countless natural and anthropogenic modifications that occurred over the past centuries. The AIA involved the analysis of a variety of datasets acquired through historical, archaeological, geomorphologic and palaeo-environmental investigations coupled with information retrieved by remote sensing imagery analysis and interpretation, and direct survey. The analysis of these datasets led to the identification of a new, large archaeological site located along the planned pipeline track. The elevated ‘archaeological sensitivity’ of this area caused a change in the project plan, resulting in the relocation of the original pipeline track at an early stage of the work.

Podvodna arheološka istraživanja rimske luke u uvali Janice provedena su u godinama 2004., 2011. i 2012. Iako su na Janicama prvo započeta istraživanja ranorimske luke, arheološki interes pomaknuo se prema obližnjem prapovijesnom nalazištu, koje je otkrio Marko Meštrov. Na početku istraživanja prapovijesnoga nalazišta identificirano je nekoliko položaja s većom gustoćom površinskih nalaza keramičkih ulomaka i kremenih alatki. Na tim položajima sljedeće su godine postavljene dvije arheološke sonde veličine 2 x 1 m. U obje sonde pronađena je velika količina ulomaka keramike, kremenih alatki i nešto ulomaka kostiju, a u sondi 1 pronađeni su drveni elementi već na 10 cm dubine. Svi ovi nalazi mogu se datirati u neolitik ili eneolitik. Značajna količina prikupljenih kremenih alatki, keramike i organskoga materijala te višeslojnost nalazišta svjedoče o naseljavanju ovoga položaja u dužem vremenskom razdoblju. Još uvijek se ne može pouzdano reći o kakvom je karakteru naselja ovdje riječ, a...

In this paper, in order to overcome certain limitations of previously commercialized platforms, a new integrated unmanned surface vehicle (USV) and unmanned underwater vehicle (UUV) platform connected via underwater cable capable of acquiring real-time underwater data and long-time operation are studied. A catamaran-type USV was designed to overcome the limitations of an ocean environment and to play the role as the hub of power supply and communication for the integrated platform. Meanwhile, the UUV was designed as torpedo-shaped to minimize hydrodynamic resistance and its hardware design was focused on processing and sending the underwater camera and sonar data. The underwater cable driven by a winch system was installed to supply power from the USV to the UUV and to transmit acquired data form underwater sonar sensor or camera. Different from other previously studied cooperation system of USVs and autonomous underwater vehicles (AUVs), the merit of the proposed system is real-tim...

Clean water supply is important in ensuring good health of people. Water supply is distributed from water storage tanks. Sediment that accumulates over time in water storage tanks will deteriorate the water quality used by consumers. Therefore, water storage tanks are required to be cleaned once in every three years by water utility operators or tank cleaning service providers. Manual cleaning method is done by draining off and resupply water into the tank after workers have cleaned the tank using water jet and brushes. In this paper, an alternative cleaning method using a Remotely Operated Underwater Vehicle (ROV) is proposed.  Using ROV, water supply disruption can be prevented and cleaning process will be more efficient and cost effective. An ROV is built to operate underwater and vacuum out sediments from water tank. Operator on screen can see live-streaming video. Raspberry Pi is used as the main communication board to interface with MATLAB. Operator will operates the ROV remot...

This paper presents a comprehensive overview of current deep-learning methods for automatic object classification of underwater sonar data for shoreline surveillance, concentrating mostly on the classification of vessels from passive sonar data and the identification of objects of interest from active sonar (such as minelike objects, human figures or debris of wrecked ships). Not only is the contribution of this work to provide a systematic description of the state of the art of this field, but also to identify five main ingredients in its current development: the application of deep-learning methods using convolutional layers alone; deep-learning methods that apply biologically inspired feature-extraction filters as a preprocessing step; classification of data from frequency and time–frequency analysis; methods using machine learning to extract features from original signals; and transfer learning methods. This paper also describes some of the most important datasets cited in the l...

Remotely Operated Vehicle (ROV) for underwater exploration is typically controlled using umbilical cable connected to ground control station. Unfortunately, while it's used for power distribution and data transmission, it also obstruct the movement of ROV especially for shallow water (<50 cm). This paper proposed an alternative method for controlling ROV using wireless remote control system. This work also aims to explore the possibility of using RF wireless technology between 420-450 MHz as underwater communication system. Furthermore, the control system was used to manage actuators i.e. DC motor and bilge pump for maneuvring and picking small size cargo. To help the ROV to hold on a desired, Inertial Measurement Unit (IMU) is installed on board ROV within maximum deviation 0.2 m/s2. The prototype of the system has been successfully implemented and evaluated to confirm the functionality and the feasibility of the proposed approach.

ABSTRACT This article proposes a new formalism for the dynamic modelling of cables that can even be applied when they are submitted to cross flow of water or air. An important application is the case of umbilical cables used in remotely operated vehicles. The primary basis for the formulation is to assume that the continuous flexibility is represented by a discrete approach, consisting of rigid links connected by elastic joints, allowing movement in three dimensions. Each elastic joint allows three independent movements, called elevation, azimuth and torsion (twist). A significant contribution of the proposed formalism is the development of a compact equation that allows obtaining the Lagrangian of the system directly and automatically, regardless of the number of links chosen to form a chain of rigid bodies connected by flexible joints to represent the continuous flexibility of the cable. This formulation allows the construction of an algorithm for obtaining the equations of the dynamic model of flexible cables.

Tijekom razdoblja rimske prevlasti na Sredozemlju pomorski su putovi bili važni kanali za razmjenu robe između udaljenih dijelova Carstva. Ti su se putovi mijenjali tijekom stoljeća zbog političkih, gospodarskih i drugih razloga. Cilj je ovog rada predstaviti razlike u fluktuaciji uvoza i izvoza između istočne obale Jadrana, Italije i ostalih rimskih provincija na temelju nalaza amfora u Hrvatskoj iz razdoblja od 1. do 6. stoljeća. Amfore su zasigurno najčešći nalaz u istraživačkim kampanjama podvodne arheologije. Iako su uglavnom služile kao spremnici i ambalaža tijekom prijevoza robe, danas su bogat izvor informacija o teretu određenog broda: o podrijetlu, vrsti i veličini broda, lukama u kojima je pristajao i mnogočemu drugome. Isto tako, mnogo se informacija može doznati proučavanjem skupina amfora iz luka i drugih obalnih nalazišta.

Underwater photogrammetry provides a means of generating high-resolution products such as dense point clouds, 3D models, and orthomosaics with centimetric scale resolutions. Underwater photogrammetric models can be used to monitor the growth and expansion of benthic communities, including the assessment of the conservation status of seagrass beds and their change over time (time lapse micro-bathymetry) with OBIA classifications (Object-Based Image Analysis). However, one of the most complex aspects of underwater photogrammetry is the accuracy of the 3D models for both the horizontal and vertical components used to estimate the surfaces and volumes of biomass. In this study, a photogrammetry-based micro-bathymetry approach was applied to monitor Posidonia oceanica restoration actions. A procedure for rectifying both the horizontal and vertical elevation data was developed using soundings from high-resolution multibeam bathymetry. Furthermore, a 3D trilateration technique was also tes...

This chapter examines, in detail, the Geoarchaeological methods for both predicting and interpreting sites subjected to anthropogenic activities and taphonomic processes specific to inundated contexts. Garrison and Hale show that sediment particle-size, grain-size, and point-count studies coupled with debitage/micro-debitage analyses isolate middens deposits from those of natural origin. Chemical, faunal (primarily vertebrate), and floral proxies for anthropogenic activities were lacking, but they related the nature on inundated sites in a marine environment. The authors discuss how sea-level rise is coupled with these factors.