Sea Trial Results Research Articles

Development of a compact underwater laser-induced breakdown spectroscopy (LIBS) system and preliminary results in sea trials.

The exploitation and research of deep-sea hydrothermal vent has been an issue of great interest in ocean research in recent years. Laser-induced breakdown spectroscopy (LIBS) has great potential for ocean application due to the capabilities of stand-off, multiphase, and multielement analysis. In this work, a newly developed compact 4000m rated LIBS system (LIBSea) is introduced with preliminary results of sea trials. The underwater system consists of an Nd:YAG single-pulsed laser operating at 1064nm, an optical fiber spectrometer, an optics module, and an electronic controller module. The whole system is housed in an L800 mm×ϕ258 mm pressure housing with an optical window on the end cap. It was deployed on the remote operated vehicle Faxian on the research vessel Kexue, and in June 2015 was successfully applied for hydrothermal field measurements at the Manus area. The obtained results are shown that the LIBS system is capable of detecting elements Li, Na, K, Ca, and Mg in the hydrothermal area. Profiles of LIBS signals of elements K and Ca have also been obtained during the sea trial. The results show that the K emission line is gradually broadened with depth from sea surface to sea floor (1800m or so); the K intensity shows a hump shape with maximum value at about 1050m. The Ca emission line is rapidly broadened below 400m and slowly narrowed to the sea floor; the Ca intensity shows no obvious change below 400m and increases continuously to sea floor. A very interesting finding is that the small fluctuations of intensity profile curve of Ca show a degree of correlation with seawater temperature change. The sea trial results prove the performance of LIBSea. After further optimization, it is hoped to apply the LIBS system to the in situ mineral deposits and hydrothermal vent fluid detection in deep sea.

Uncertainty of full-scale manoeuvring trial results estimated using a simulation model

This paper describes how to estimate the uncertainty of manoeuvring sea trial results without performing repeated tests using only a simulation model. The approach is based on the Monte Carlo method of uncertainty propagation. Moreover, the global sensitivity analysis procedure based on variance decomposition is described. As an example, the method is applied to estimate the uncertainty of 10°/10° zigzag overshoot angles and a 20° turning circle advance and tactical diameter for a small research vessel. The estimated uncertainty is compared with corresponding experimental uncertainty assessed from repeated tests. The method can be useful for validation studies and other studies that involve the uncertainty of sea trial results.

Joint inversion for transponder localization and sound-speed profile temporal variation in high-precision acoustic surveys.

This letter develops a Bayesian inversion for localizing underwater acoustic transponders using a surface ship which compensates for sound-speed profile (SSP) temporal variation during the survey. The method is based on dividing observed acoustic travel-time data into time segments and including depth-independent SSP variations for each segment as additional unknown parameters to approximate the SSP temporal variation. SSP variations are estimated jointly with transponder locations, rather than calculated separately as in existing two-step inversions. Simulation and sea-trial results show this localization/SSP joint inversion performs better than two-step inversion in terms of localization accuracy, agreement with measured SSP variations, and computational efficiency.

정수중을 활주하는 고속선의 6자유도 운동 모델링 및 시뮬레이션

When a planing hull straightly runs and turns, its floating position and pitch angle are changed depending on its speed, and large transient motion happens. In this paper, six degrees of freedom(6 DOF) equations of motion, which could simulate the motion of a planing hull, are established. Static and dynamic forces in vertical plane are modeled using pre-calculated displacements and metacentric heights depending on various draft, lift under bottom, and vertical damping coefficients which are used to tune the final motion. Hydrodynamic coefficients in horizontal plane at various equilibrium state are calculated by using Lewandowski's empirical formula and the speed-dependent equilibrium state are calculated beforehand by Savitsky's formula. The speed effects are considered by curve-fitting the coefficients at various speed to the polynomials. Accelerating, decelerating and backing, turning, and zig-zag are simulated and compared with the sea trial results, and it is confirmed that the speed reduction, roll, and pitch during such maneuvers of sea trial and simulation are well consistent.

舶用SCRシステムを搭載した大型ディーゼル機関の就航試験結果

The International Maritime Organization (IMO) has decided to implement a tighter limit for nitrogen oxide (NOx) emissions from ships operating in emission control areas (ECA) from 2016. Hitachi Zosen Corporation has developed a marine SCR system to denitrate exhaust gas of large two-stroke diesel engines in order to comply with the IMO regulation. Nippon Kaiji Kyokai issued a certificate attesting that certifies a large two-stroke diesel engine Hitachi-MAN B&W 6S46MC-C7 fitted with the SCR system achieved the NOx emission level required by the IMO regulation. The system was installed on a new-built vessel, and verification tests were carried out for a long period.In this paper, we will present a summary of the marine SCR system, and report on sea trial results of the marine SCR system installed on the new-built vessel, as well as those of a similar SCR system installed on a multi-cylinder test diesel engine in order to solve technical issues encountered during long-term service test.

쇄빙연구선 "Araon"호를 활용한 빙해역 속력 시운전에 관한 연구

To know the speed performance of “ARAON” in Arctic ice field, the measurement of ice properties which is ice thickness & strength, snow depth and free board were performed on July 2010. The measuring method of nautical signals such as heading angle, power of engine, wind & current information etc. was described in this paper. The speed sea trials in ice were performed on the four different positions with different ice properties and engine powers because the uniform level ice is not detected in the Chukchi Sea. The test field was partially constrained ice floe with hummocks and it was superposed with small broken ice pieces each other. All of the measured ice properties were compared and evaluated according to the results of sea trial. The relations between speed, ice thickness, strength and power were summarized. Consequently according to the sea trial results, the speed of ARAON is 2.78knots at the 2.49m ice thickness with 6.55MW engine power.

Study of the Sealing Characteristic of Polytetrafluoroethylene-Coated O-Ring Applied in Gas-Tight Deep-Sea Water Sampler

In ocean science research, it often requires the integrity of the gas content in samples of seawater. The gas-tight deep-sea water sampler (GTWS) based on pressure self-adaptive equalizer (PSAE) can satisfy the requirement very well. The PSAE is required to achieve a reliable dynamic sealing in deep sea. The general O-ring is difficult to meet this requirement. The polytetrafluoroethylene (PTFE)-coated O-ring is chosen as the sealing parts. The finite element analysis (FEA) software ANSYS is used to analyze the contact pressure of the PTFE-coated O-ring in different conditions, that is, analyze the GTWS’s gas tightness theoretically. Combine with the sea trial results, the feasibility and reliability of the PTFE-coated O-ring in deep-sea dynamic sealing in PSAE can be prove both in theory and practice.

Antisubmarine warfare applications for autonomous underwater vehicles: The GLINT09 sea trial results

AbstractSurveillance in antisubmarine warfare (ASW) has traditionally been carried out by means of submarines or frigates with towed arrays. These techniques are manpower intensive. Alternative approaches have recently been suggested concerning distributed mobile and stationary sensors, such as sonobuoys and autonomous underwater vehicles (AUVs). To field a fully operational system, many technological hurdles need to be overcome. These include battery life, limited acoustic communications ranges, incorporating sonar signal processing on the AUV's embedded hardware, and increasing autonomy to ensure that the system as a whole acts in a sensible and appropriate fashion. The main thrust of this paper is how the latter two issues have been addressed for a real experimental system and how the proposed solutions have been demonstrated at sea. This paper describes ongoing development at the NATO Undersea Research Centre (NURC) to construct an autonomous distributed sensor system that uses AUVs for ASW applications. In a series of at‐sea experiments, we have demonstrated real‐time processing—incorporating traditional ASW processing as far as tracking—and adaptive autonomous behaviors, which concern AUV navigation to optimize target localization. This paper describes the hardware and software configurations that facilitated the rapid development of this system and details the recent at‐sea successes that have been demonstrated with our AUV, towed arrays, and active acoustic sources. Results are given of our most recent at‐sea trial, GLINT09, held in the summer of 2009, when an AUV with a towed array detected and maneuvered in response to an active source. © 2010 Wiley Periodicals, Inc.

Study on the form factor and full-scale ship resistance prediction method

To consider the resistance component due to hull geometry, the International Towing Tank Conference (ITTC) adopted the resistance test method in 1978, introducing the form factor concept with two basic assumptions, i.e., the form factor of a model ship is the same as that of a full-scale ship and the form factor is independent of ship speed. However, it is not only very difficult to determine the form factor using the ITTC ’78 method, but also there have been questions regarding the basic assumptions. Therefore, the authors carried out three basic studies on the form factor concept and proposed a new extrapolation procedure for the prediction of full-scale ship resistance performance. The validity of the proposed procedure is being investigated by comparing sea trial and model test results. The results of this investigation will be presented in the near future.

20709 深海生物追跡ロボット"PICASSO"による実海域における様々な試み(水中ロボット,OS.13 水中ロボット,学術講演)

PICASSO (Plankton Investigatory Collaborating Autonomous Survey System Operon) is a special purpose underwater vehicle for plankton survey in mid-water. According to the conventional plankton research method, planktons are directly hauled with plankton net. Some planktons which have fragile body are broken by the net method and then the planktons caught becomes ineffective as research material. PICASSO provides state-of the-art method for plankton investigation. A high definition television camera and a visual plankton recorder which are equipped with PICASSO take high resolution plankton image. Scientists can make in-situ classification of planktons using the image obtained. We carried out three times sea trials and made 24 deployments. We present some devices developed for PICASSO and these sea trial results.

Engineering development of flexible selectivity grids for Nephrops

There are different approaches to selectivity, including increasing cod-end mesh size, square mesh panels and rigid grids. Selectivity grids have traditionally been produced to be as rigid as possible to maintain spacing but this can result in heavy, expensive grids, handling problems and brittleness. This paper presents an alternative approach using flexible polyurethane polymers to produce lightweight inexpensive grids with much improved damage tolerance and ease of handling, which also possess interesting selectivity characteristics. The material selection, design and development tests are described first, then preliminary sea trial results are presented. A flexible grid with a 20 mm spacing between bars performed successfully and enabled a reduction in juvenile catch of 87% by weight to be achieved, but also significant loss of commercial catch. Further development will concentrate on reducing the spacing to optimise selectivity.

Double Acting Tanker: Experiences from Model Tests and Sea Trials

The acronym DAT stands for double acting tanker, a concept where the ship is designed to run astern in heavy ice conditions while remaining hydrodynamically efficient for ahead propulsion in open water conditions. Two large aframax DATs - 106.000 dwt (deadweight tons) each - have been delivered by Sumitomo Heavy Industries to Fortum Oil and Gas OY. They are the first crude carriers built according to the DAT principle and also the first using pod propulsion from the beginning (Fig. 1). They will also be the world's largest crude carriers with ice class 1A super and are primarily intended for year-round transportation of North Sea crude to Fortum's refineries in the Gulf of Finland. The ships were appointed ‘ship of the year’ in Japan in 2003. SSPA was contracted by Sumitomo Heavy Industries to perform model tests. A comprehensive open water model test programme was used to investigate aspects of resistance and propulsion, manoeuvring, and cavitation performance. As the ship is designed to operate both in ahead and astern conditions for prolonged periods of time, most tests were performed both ahead and astern. Also, a simulation study of dynamic positioning at buoy or floating production, storage offshore (FPSO) loading was made by SSPA. Comprehensive tests of the ship's performance in ice were performed in the ice tank at MARC (Masa-Yards Artic Research Centre). The eight-month model testing and development campaign resulted in a ship with excellent propulsion and manoeuvring performance, especially with regard to the high ice class. Sea trials carried out with ship in August 2002 confirmed the results of the model test. Interesting experiences of the model test campaign and comparison between model test and sea trial results are presented, as well as some examples of single-point mooring simulations.

Performance of the fuel cell underwater vehicle URASHIMA

The Japan Agency for Marine-Earth Science and Technology acquired an autonomous underwater vehicle, the URASHIMA, in 2000. It has capacity to cruise for 300 km, and to dive up to 3,500 m depth, and it can approach waypoints correctly using inertial or acoustic navigation during autonomous cruising. Autonomous underwater vehicles are expected to explore environmental problems by measuring various oceanic data. Through sea trials, we have been developing key technologies for the vehicle, such as navigation and power sources. This paper describes the vehicle system and sea trial results.

Sea trial results of a robust and spectral-efficient OFDM underwater communication system

In single-carrier, high data-rate systems symbol durations are much smaller than channel delay spreads. Reliable equalization in such systems is extremely difficult to attain because the channel is time varying and highly frequency selective. One way to circumvent the need of using costly equalization schemes, while maintaining high data rates, is to use multicarrier modulation in which broadband data is transmitted in parallel on multiple narrowband subcarriers. Symbol duration T in such systems is usually larger than delay spreads such that each narrowband subcarrier experiences only nonfrequency-selective flat fading. To improve spectral efficiency and eliminate the use of guard bands between subcarriers, each subcarrier can be chosen to be orthogonal to the others. Such a multicarrier system is referred to as orthogonal frequency division multiplexing (OFDM). Unfortunately, the orthogonality is destroyed in typical underwater channels due to large Doppler shifts and spreads (compared to the inverse of symbol durations). Therefore, previous work in UWA required the spacing of adjacent subcarriers to be 2/T, which is twice the minimum spacing 1/T. In this paper, time-rescaling and pilot-symbol aided channel estimation techniques are employed to combat Doppler shift and spreads. Reliable results are obtained with 1/T subcarrier spacing in sea trials.

Sea Trial Results of a Cross Fan Beam Type Sub-Bottom Profiler

Based on a joint development with SEABEAM Instruments of the U.S., we were the first in the world to develop a cross fan beam type high-resolution narrow beam sub-bottom profiler(SBP) that consisted of a transducer array fitted to a ship bottom. After completion, the resolving power was investigated by targeting a sunken ship, and as a result, the horizontal resolution was estimated to be approximately 3.5 degrees, while the vertical resolution was estimated to be about 2 m. Furthermore, comparison with the parametric high-resolution SBP revealed that the performance of the cross fan beam type SBP was by no means inferior.

Adaptive Doppler compensation for coherent acoustic communication

Doppler shift tracking and compensation based on block and adaptive estimation methods are presented. These methods enable robust high data-rate acoustic communication between moving platforms such as autonomous underwater vehicles. The proposed schemes are incorporated within a wideband beamforming array with decision feedback equalisation. The block-based Doppler compensator is used as a pre-processor to the beamforming structure, whereas the adaptive compensator and the beamforming structure are jointly updated. The two methods employ multirate sampling and linear interpolation to compensate for the Doppler shift. Simulation and experimental sea-trial results are reported for both block and adaptive methods, which demonstrate successful communication at 16 kbit/s with a transmitting platform moving at up to ±2.6 m/s.

Autonomous bathymetry survey system

This paper describes the Autonomous Bathymetry Survey System (AutoSurvey), a system that provides automation of swath sonar bathymetric surveys. This system enables faster surveying of an area through environmentally adaptive techniques while ensuring adequate coverage and data quality. AutoSurvey assesses data quality and coverage in real time and generates next-trackline waypoints based on actual system performance. The need for real-time performance assessment is discussed. A primary factor considered is the effect of the environment on swath bathymetry system performance, which is difficult to predict a priori. The system's features, design, and implementation are discussed in this paper. Simulation and sea trial results are presented, as well as an analysis of the system's ability to reduce survey time.

Full Scale Sea Trials with Optimal Thrust Allocation

Thrust allocation for ship control like dynamic positioning is the problem of determining the thrust and the direction of each of the n thruster devices of a ship given the desired forces and moment from the control law. This paper presents full scale sea trials with a thrust allocation scheme that avoids problems with singular aziumuth configurations and minimizes the required thrust and power. The sea trials show that the fuel consumption is reduced with more than 30% with this proposed approach compared to a more conventional approach. In addition to presenting the sea trial results, the theory behind the thrust allocation is presented.

船内LANによるデータ処理システム

A new data acquisition system by using the Ethernet LAN has been developed in cooperation with the authors and Sena Co. The data acquisition system has been installed in the T. S. OSHIMAMARU which belongss to Oshima National College of Maritime Technology.This paper describes the outline of the system mentioned above and the sea trial results. The test records show the load change clearly due to the operation of the ship. Finally, the data acquisition system proposed newly is proved to be a very useful one by illustrating the results of our experiments.

Infrared Signature Suppression for Marine Gas Turbines: Comparison of Sea Trial and Model Test Results for the DRES Ball IRSS System

Sea Trials have recently been underway for Canada’s new City Class Patrol Frigate (CPF). These trials provided the first opportunity to measure the performance of the new DRES Ball Infrared Signature Suppression (IRSS) system installed on a ship. Prior to these trials 1/4-scale hot flow model test and computer simulation performance results were available. The CPF DRES Ball IRSS systems are installed on the exhaust uptakes of the GE LM2500 main gas turbines. The DRES Ball provides both metal surface cooling for all view angles and plume cooling. The DRES Ball significantly reduces the IR signature of the LM2500 exhaust. This paper presents a comparison between the 1/4-scale hot flow model test results with the full-scale sea trial results. Performance variables included in the comparison are: metal surface temperatures, back pressure, plume temperature distribution, and surface static pressures. Because of the confidential nature of the DRES Ball system performance, all classified data have been nondimensionalized so that only relative comparisons can be made between the full-scale and 1/4-scale data. The results show that the full-scale system performs better than the 1/4-scale model because of Reynolds number effects. The plume temperature, surface temperatures, and back pressure were all lower (better) than in the 1/4-scale model tests. One of the original concerns with the installation was that relative wind would degrade the performance of the DRES Ball onboard a ship. The wind effect was found to be benign during the trials.