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J. Mar. Sci. Eng., Volume 5, Issue 1 (March 2017)

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Cover Story In power industry, intake and discharge systems are known as the bloodlines of every power plant, [...] Read more.
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Editorial

Jump to: Research, Review

Open AccessEditorial Acknowledgement to Reviewers of JMSE in 2016
J. Mar. Sci. Eng. 2017, 5(1), 6; doi:10.3390/jmse5010006
Received: 12 January 2017 / Revised: 12 January 2017 / Accepted: 12 January 2017 / Published: 12 January 2017
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Abstract
The editors of JMSE would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016. We greatly appreciate the contribution of expert reviewers, which is crucial to the journal’s editorial process. We aim to recognize reviewer contributions through
[...] Read more.
The editors of JMSE would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016. We greatly appreciate the contribution of expert reviewers, which is crucial to the journal’s editorial process. We aim to recognize reviewer contributions through several mechanisms, of which the annual publication of reviewer names is one. Reviewers receive a voucher entitling them to a discount on their next MDPI publication and can download a certificate of recognition directly from our submission system. Additionally, reviewers can sign up to the service Publons (https://publons.com) to receive recognition. Of course, in these initiatives we are careful not to compromise reviewer confidentiality. Many reviewers see their work as a voluntary and often unseen part of their role as researchers. We are grateful to the time reviewers donate to our journals and the contribution they make. Full article

Research

Jump to: Editorial, Review

Open AccessFeature PaperArticle Role of Beach Morphology in Wave Overtopping Hazard Assessment
J. Mar. Sci. Eng. 2017, 5(1), 1; doi:10.3390/jmse5010001
Received: 18 August 2016 / Revised: 2 December 2016 / Accepted: 19 December 2016 / Published: 5 January 2017
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Abstract
Understanding the role of beach morphology in controlling wave overtopping volume will further minimise uncertainties in flood risk assessments at coastal locations defended by engineered structures worldwide. XBeach is used to model wave overtopping volume for a 1:200 year joint probability distribution of
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Understanding the role of beach morphology in controlling wave overtopping volume will further minimise uncertainties in flood risk assessments at coastal locations defended by engineered structures worldwide. XBeach is used to model wave overtopping volume for a 1:200 year joint probability distribution of waves and water levels with measured, pre- and post-storm beach profiles. The simulation with measured bathymetry is repeated with and without morphological evolution enabled during the modelled storm event. This research assesses the role of morphology in controlling wave overtopping volumes for hazardous events that meet the typical design level of coastal defence structures. Results show that disabling storm-driven morphology under-represents modelled wave overtopping volumes by up to 39% under high H s conditions and has a greater impact on the wave overtopping rate than the variability applied within the boundary conditions due to the range of wave-water level combinations that meet the 1:200 year joint probability criterion. Accounting for morphology in flood modelling is therefore critical for accurately predicting wave overtopping volumes and the resulting flood hazard and to assess economic losses. Full article
(This article belongs to the Special Issue Modelling Waves in Coasts and Estuaries)
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Open AccessArticle Multi-Layered Stratification in the Baltic Sea: Insight from a Modeling Study with Reference to Environmental Conditions
J. Mar. Sci. Eng. 2017, 5(1), 2; doi:10.3390/jmse5010002
Received: 18 July 2016 / Revised: 29 November 2016 / Accepted: 7 December 2016 / Published: 7 January 2017
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Abstract
The hydrodynamic and transport characteristics of the Baltic Sea in the period 2000–2009 were studied using a fully calibrated and validated 3D hydrodynamic model with a horizontal resolution of 4.8 km. This study provided new insight into the type and dynamics of vertical
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The hydrodynamic and transport characteristics of the Baltic Sea in the period 2000–2009 were studied using a fully calibrated and validated 3D hydrodynamic model with a horizontal resolution of 4.8 km. This study provided new insight into the type and dynamics of vertical structure in the Baltic Sea, not considered in previous studies. Thermal and salinity stratification are both addressed, with a focus on the structural properties of the layers. The detection of cooler regions (dicothermal) within the layer structure is an important finding. The detailed investigation of thermal stratification for a 10-year period (i.e., 2000–2009) revealed some new features. A multilayered structure that contains several thermocline and dicothermal layers was identified from this study. Statistical analysis of the simulation results made it possible to derive the mean thermal stratification properties, expressed as mean temperatures and the normalized layer thicknesses. The three-layered model proposed by previous investigators appears to be valid only during the winter periods; for other periods, a multi-layered structure with more than five layers has been identified during this investigation. This study provides detailed insight into thermal and salinity stratification in the Baltic Sea during a recent decade that can be used as a basis for diverse environmental assessments. It extends previous studies on stratification in the Baltic Sea regarding both the extent and the nature of stratification. Full article
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Open AccessArticle Information Theoretic Source Seeking Strategies for Multiagent Plume Tracking in Turbulent Fields
J. Mar. Sci. Eng. 2017, 5(1), 3; doi:10.3390/jmse5010003
Received: 31 May 2016 / Revised: 11 November 2016 / Accepted: 28 November 2016 / Published: 12 January 2017
Cited by 1 | PDF Full-text (2672 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
We present information theoretic search strategies for single and multi-robot teams to localize the source of biochemical contaminants in turbulent flows. The robots synthesize the information provided by sporadic and intermittent sensor readings to optimize their exploration strategy. By leveraging the spatio-temporal sensing
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We present information theoretic search strategies for single and multi-robot teams to localize the source of biochemical contaminants in turbulent flows. The robots synthesize the information provided by sporadic and intermittent sensor readings to optimize their exploration strategy. By leveraging the spatio-temporal sensing capabilities of a mobile sensing network, our strategies result in control actions that maximize the information gained by the team while minimizing the time spent localizing the biochemical source. By leveraging the team’s ability to obtain simultaneous measurements at different locations, we show how a multi-robot team is able to speed up the search process resulting in a collaborative information theoretic search strategy. We validate our proposed strategies in both simulations and experiments. Full article
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Open AccessArticle Evaluating the Reliability of Counting Bacteria Using Epifluorescence Microscopy
J. Mar. Sci. Eng. 2017, 5(1), 4; doi:10.3390/jmse5010004
Received: 25 October 2016 / Revised: 6 December 2016 / Accepted: 8 December 2016 / Published: 8 January 2017
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Abstract
The common practice of counting bacteria using epifluorescence microscopy involves selecting 5–30 random fields of view on a glass slide to calculate the arithmetic mean which is then used to estimate the total bacterial abundance. However, not much is known about the accuracy
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The common practice of counting bacteria using epifluorescence microscopy involves selecting 5–30 random fields of view on a glass slide to calculate the arithmetic mean which is then used to estimate the total bacterial abundance. However, not much is known about the accuracy of the arithmetic mean when it is calculated by selecting random fields of view and its effect on the overall abundance. The aim of this study is to evaluate the accuracy and reliability of the arithmetic mean by estimating total bacterial abundance and to calculate its variance using a bootstrapping technique. Three fixed suspensions obtained from a three-week-old marine biofilm were stained and dispersed on glass slides. Bacterial cells were counted from a total of 13,924 fields of view on each slide. Total bacterial count data obtained were used for calculating the arithmetic mean and associated variance and bias for sample field sizes of 5, 10, 15, 20, 25, 30, 35 and 40. The study revealed a non-uniform distribution of bacterial cells on the glass slide. A minimum of 20 random fields of view or a minimum of 350 bacterial cells need to be counted to obtain a reliable value of the arithmetic mean to estimate the total bacterial abundance for a marine biofilm sample dispersed on a glass slide. Full article
(This article belongs to the Section Marine Biology)
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Open AccessArticle Thermal Recirculation Modeling for Power Plants in an Estuarine Environment
J. Mar. Sci. Eng. 2017, 5(1), 5; doi:10.3390/jmse5010005
Received: 27 October 2016 / Revised: 11 December 2016 / Accepted: 30 December 2016 / Published: 12 January 2017
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Abstract
Many power plants require large quantities of water for cooling purposes. The water taken from the source water body (e.g., lakes, estuaries, bays and rivers) circulates through the plant and returns to the source through outfall with a higher temperature. For optimal performance
[...] Read more.
Many power plants require large quantities of water for cooling purposes. The water taken from the source water body (e.g., lakes, estuaries, bays and rivers) circulates through the plant and returns to the source through outfall with a higher temperature. For optimal performance of the power plant, the intake inlet and discharge outlet should be meticulously placed so that the heated water will not recirculate back into the power plant. In this study, the Flow module of the Delft3D software is employed to simulate the temperature transport within the study area in three-dimensional and nested format. Model results are used to optimize the location of intake inlets, outfall outlets and diffuser port orientations. The physical processes used in the study are tidal fluctuations, winds, river discharges, salinity and temperature. The subject power plant (power plant parameters presented in this paper are realistic; however, they do not target any specific power plant within the study area) has a nominal capacity of 2600 MW and is planned to be located in Delaware Bay, USA. Existing field measurements are used to calibrate the model in a coupled two-staged fashion for main tidal constituents, currents and water temperature. The sensitivity of the model against various input parameters is tested, and conservative values are selected. The location of the intake is fixed, and the location of the outfall is changed until the thermal impact to the intake is less than 1 °C. Analysis of the results shows that there is a linear logarithmic relation between the excess temperatures at the intake inlet and horizontal eddy diffusivity. The k - ϵ turbulence closure results in higher excess temperature and a more conservative design. Extending the outfall location to the deeper portion of the estuary combined with port orientations reduces the impact by keeping the thermal plume away from the intake inlet and meeting the established criteria. It is concluded that an approximate distance of 1300 m is the optimal location for the power plant outfall outlets. In addition, the diffuser ports should not discharge the heated water toward the intake and have to be oriented away from the line connecting outfall to the intake. Full article
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Open AccessArticle Characterization of the New Status of Nador Lagoon (Morocco) after the Implementation of the Management Plan
J. Mar. Sci. Eng. 2017, 5(1), 7; doi:10.3390/jmse5010007
Received: 9 October 2016 / Revised: 30 December 2016 / Accepted: 4 January 2017 / Published: 13 January 2017
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Abstract
The present study was carried out in 2011 with the aims of (1) evaluating the changes in sedimentary distribution that occurred in Nador lagoon seabed (Morocco) after the implementation of the lagoon management plan in 2009; and (2) characterizing its new sedimentary status
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The present study was carried out in 2011 with the aims of (1) evaluating the changes in sedimentary distribution that occurred in Nador lagoon seabed (Morocco) after the implementation of the lagoon management plan in 2009; and (2) characterizing its new sedimentary status in 2011. Due to the lack of a baseline, we used the 1992 sedimentary status for comparison. The seabed surface sediment distribution showed a great change between 1992 and 2011. We found the same four sediment facies, which were present in 1992, namely: mud, sandy mud, muddy sand, and fine sand. However, in 2011, mud covered more than 54% of the lagoon seabed surface, mostly located in the middle part of the seabed, whereas in 1992, more than 80% of the lagoon seabed was covered by sandy mud. The sediments’ characteristics showed moderately to poorly sorted facies (S0), ranging between platykurtic and leptokurtic (SK) and with various symmetry indices (SG). The organic matter content in sediment has strongly decreased, from values higher than 20% in most areas in 1992 to a mean value of 3.9% in 2011, ranging from 0.2% to 10.4%, thus confirming that the management actions implemented in 2009 were likely effective in reducing the organic pollution. Full article
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Open AccessArticle Towards the Development of an Operational Forecast System for the Florida Coast
J. Mar. Sci. Eng. 2017, 5(1), 8; doi:10.3390/jmse5010008
Received: 18 July 2016 / Revised: 14 December 2016 / Accepted: 5 January 2017 / Published: 13 January 2017
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Abstract
A nowcasting and forecasting system for storm surge, inundation, waves, and baroclinic flow for the Florida coast has been developed. The system is based on dynamically coupled CH3D and SWAN models and can use a variety of modules to provide different input forcing,
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A nowcasting and forecasting system for storm surge, inundation, waves, and baroclinic flow for the Florida coast has been developed. The system is based on dynamically coupled CH3D and SWAN models and can use a variety of modules to provide different input forcing, boundary and initial conditions. The system is completely automated and operates unattended at pre-scheduled intervals as well as in event-triggered mode in response to Atlantic-basin tropical cyclone advisories issued by the National Hurricane Center. The system provides up to 72-h forecasts forward depending on the input dataset duration. Spatially, the system spans the entire Florida coastline by employing four high-resolution domains with resolutions as fine as 10–30 m in the near-shore and overland to allow the system to resolve fine estuarine details such as in the Intracoastal Waterway and minor tributaries. The system has been validated in both hindcast and nowcast/forecast modes using water level and salinity data from a variety of sources and has been found to run robustly during the test periods. Low level products (e.g., raw output datasets) are disseminated using THREDDS while a custom defined web-based graphical user interface (GUI) was developed for high level access. Full article
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Open AccessFeature PaperArticle Energy Balance of Biogas Production from Microalgae: Effect of Harvesting Method, Multiple Raceways, Scale of Plant and Combined Heat and Power Generation
J. Mar. Sci. Eng. 2017, 5(1), 9; doi:10.3390/jmse5010009
Received: 9 September 2016 / Revised: 30 December 2016 / Accepted: 18 January 2017 / Published: 25 January 2017
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Abstract
A previously-developed mechanistic energy balance model for production of biogas from the anaerobic digestion of microalgal biomass grown in open raceway systems was used to consider the energetic viability of a number of scenarios, and to explore some of the most critical parameters
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A previously-developed mechanistic energy balance model for production of biogas from the anaerobic digestion of microalgal biomass grown in open raceway systems was used to consider the energetic viability of a number of scenarios, and to explore some of the most critical parameters affecting net energy production. The output demonstrated that no single harvesting method of those considered (centrifugation, settlement or flocculation) produced an energy output sufficiently greater than operational energy inputs to make microalgal biogas production energetically viable. Combinations of harvesting methods could produce energy outputs 2.3–3.4 times greater than the operational energy inputs. Electrical energy to power pumps, mixers and harvesting systems was 5–8 times greater than the heating energy requirement. If the energy to power the plant is generated locally in a combined heat and power unit, a considerable amount of “low grade” heat will be available that is not required by the process, and for the system to show a net operational energy return this must be exploited. It is concluded that the production of microalgal biogas may be energetically viable, but it is dependent on the effective use of the heat generated by the combustion of biogas in combined heat and power units to show an operational energy return. Full article
(This article belongs to the Special Issue Algal Biofuels)
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Open AccessArticle Application of State of Art Modeling Techniques to Predict Flooding and Waves for an Exposed Coastal Area
J. Mar. Sci. Eng. 2017, 5(1), 10; doi:10.3390/jmse5010010
Received: 21 November 2016 / Revised: 6 January 2017 / Accepted: 11 January 2017 / Published: 4 February 2017
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Abstract
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure in the coastal zone from storm surge and coincidental waves. The maps are used by state agencies and
[...] Read more.
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure in the coastal zone from storm surge and coincidental waves. The maps are used by state agencies and municipalities to help guide coastal planning and establish the minimum elevation standard for new or substantially improved structures. A summary of the methods used and results of 2012 FIRM mapping are presented for Charlestown, RI; a coastal community located along the exposed, southern shoreline of the state. Concerns with the methods used in the 2012 analysis are put in context with the National Research Council’s (NRC) 2009 review of the FEMA coastal mapping program. New mapping is then performed using state of the art, fully coupled surge and wave modeling and data analysis methods to address the concerns in the NRC review. The new maps and methodologies are in compliance with FEMA regulations and guidelines. The approach makes extensive use of the numerical modeling results from the recent US Army Corp of Engineers (USACE), North Atlantic Coast Comprehensive Study (NACCS 2015). Revised flood maps are presented and compared with the 2012 FIRM map to provide insight into the differences. The new maps highlight the importance of developing better estimates of offshore surge dynamics and its coupling to waves, dune erosion based on local observations, and the advancement in nearshore mapping of waves in flood inundated areas by the use of state of the art, two-dimensional wave transformation models. Full article
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Open AccessArticle Scheduling of Maintenance Tasks and Routing of a Joint Vessel Fleet for Multiple Offshore Wind Farms
J. Mar. Sci. Eng. 2017, 5(1), 11; doi:10.3390/jmse5010011
Received: 28 October 2016 / Accepted: 6 February 2017 / Published: 10 February 2017
Cited by 1 | PDF Full-text (827 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Maintenance costs related to offshore wind farms are severely limiting their potential for being profitable. This paper proposes a new mathematical model that considers how maintenance tasks should be scheduled and performed by technicians transported using a fleet of dedicated vessels. The model
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Maintenance costs related to offshore wind farms are severely limiting their potential for being profitable. This paper proposes a new mathematical model that considers how maintenance tasks should be scheduled and performed by technicians transported using a fleet of dedicated vessels. The model is novel in its combination of modelling several work shifts and including vessels that can stay offshore for several shifts, while handling large maintenance tasks and accurate calculation of downtime costs. Simulation is used to evaluate the performance of the model in its pure form, as well as when solved heuristically using a rolling horizon heuristic. The results indicate that the end-of-horizon effects of the mathematical formulation are handled effectively. Computational experiments also illustrate how the mathematical model coupled with simulation can be used to evaluate strategic decisions regarding the composition of a vessel fleet used to execute maintenance tasks. Full article
(This article belongs to the Special Issue Offshore Wind Energy)
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Open AccessArticle Wind-Wave Characterization in a Wind-Jet Region: The Ebro Delta Case
J. Mar. Sci. Eng. 2017, 5(1), 12; doi:10.3390/jmse5010012
Received: 15 October 2016 / Revised: 10 February 2017 / Accepted: 14 February 2017 / Published: 20 February 2017
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Abstract
This manuscript describes the wind-wave generation, development and fading in a complex area: a wind-jet region. The study region is the offshore Ebro Delta (NW Mediterranean Sea) where strong cross-shelf winds occur due to a topographic channelization. This leads to relatively short-fetch conditions,
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This manuscript describes the wind-wave generation, development and fading in a complex area: a wind-jet region. The study region is the offshore Ebro Delta (NW Mediterranean Sea) where strong cross-shelf winds occur due to a topographic channelization. This leads to relatively short-fetch conditions, which interact with the swell component. The third-generation wave model Simulating WAves Nearshore (SWAN) is implemented and fed by high-resolution wind fields. A combination of buoy and High Frequency (HF) radar data is used for model validation, resulting in a reasonable level of agreement. The numerical results characterize the wind-wave evolution during a wind jet. A bimodal spectrum is observed due to the interaction of swell and sea systems. The wave directional spreading exhibits lower values at the wind-jet axis. Finally, a reliability analysis of the wave data from an HF radar deployed at the region is carried out. Full article
(This article belongs to the Special Issue Modelling Waves in Coasts and Estuaries)
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Open AccessArticle Application of State of the Art Modeling Techniques to Predict Flooding and Waves for a Coastal Area within a Protected Bay
J. Mar. Sci. Eng. 2017, 5(1), 14; doi:10.3390/jmse5010014
Received: 26 January 2017 / Revised: 6 March 2017 / Accepted: 14 March 2017 / Published: 20 March 2017
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Abstract
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure from storm surge sand associated waves in the coastal zone. The maps are used by state agencies and
[...] Read more.
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure from storm surge sand associated waves in the coastal zone. The maps are used by state agencies and municipalities to help guide coastal planning and establish the minimum elevation and construction standards for new or substantially improved structures. A summary of the methods used and a comparison with the results of 2013 FIRM mapping are presented for Warwick, Rhode Island (RI), a coastal community located within Narragansett Bay. Because of its location, Warwick is protected from significant coastal erosion and wave attacks, but is subject to surge amplification. Concerns surrounding the FEMA methods used in the 2013 FIRM analysis are put in context with the National Research Council’s (NRC) 2009 review of the FEMA coastal mapping program. New mapping is then performed using state of the art, fully coupled surge and wave modeling, and data analysis methods, to address the NRC concerns. The new maps and methodologies are in compliance with FEMA regulations and guidelines. This new approach makes extensive use of the numerical modeling results from the recent US Army Corp of Engineers, North Atlantic Coast Comprehensive Study (NACCS, 2015). Revised flooding maps are presented and compared to the 2013 FIRM maps, to provide insight into the differences. The new maps highlight the importance of developing better estimates of surge dynamics and the advancement in nearshore mapping of waves in flood inundated areas by the use of state of the art, two-dimensional, wave transformation models. Full article
(This article belongs to the Section Ocean Engineering)
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Review

Jump to: Editorial, Research

Open AccessReview Inspection-Class Remotely Operated Vehicles—A Review
J. Mar. Sci. Eng. 2017, 5(1), 13; doi:10.3390/jmse5010013
Received: 31 January 2017 / Revised: 8 March 2017 / Accepted: 14 March 2017 / Published: 16 March 2017
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Abstract
This paper presents a review of inspection-class Remotely Operated Vehicles (ROVs). The review divides the classification of inspection-class ROVs; categorising the vehicles in order of size and capability. A state of the art technology review is undertaken, discussing various common subsystems of the
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This paper presents a review of inspection-class Remotely Operated Vehicles (ROVs). The review divides the classification of inspection-class ROVs; categorising the vehicles in order of size and capability. A state of the art technology review is undertaken, discussing various common subsystems of the ROV. Standard and novel ROV shapes and designs are reviewed, with emphasis on buoyancy, frame materials and hydrodynamics. Several power considerations and designs are discussed, accounting for battery fed and mains fed systems. ROV telemetry is split into a discussion on the various transmission hardware systems and the communication protocols that are most widely used in industry and research today. A range of thruster technologies is then introduced with consideration taken of the various thruster architectures available. Finally, the navigation and positioning sensors employed for ROV navigation and control are reviewed. The author has also created a number of comparison tables throughout the review; tables include comparison of wired data transmission technology, comparison of common ROV communication protocols and comparisons of various inertial navigation systems. By the end of the review the reader will have clearer understanding on the fundamentals of inspection-class ROV technologies and can use this as an introduction to further paper investigation. Full article
(This article belongs to the Section Ocean Engineering)
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