Examensarbetets mål är att hitta möjligheter till förbättring av navigeringsprestandahos en undervattensfarkost med hjälp av bojar utrustade med GPS. Dessabojar skickar positionsdata till farkosten som med hjälp av ett extended kalmanfilter(EKF) integrerar denna information till att förbättra sin navigering.Ett ytterligare mål med examensarbetet har även varit att skapa en simuleringsmiljöför en liten farkost, där eventuella nya algoritmer eller sensorer, vidframtida behov, på ett smidigt sätt skall kunna integreras för utprovning. Dettahar i arbetet inneburit en anpassning av en fysikalisk 6-DOF modell till enliten undervattensfarkost samt en reglerdesign för detta system i form av kaskadkoppladePI-regulatorer och parameterstyrning. Simuleringsmiljön är skapad medhjälp av Matlab och Simulink. / The goal of this master thesis is to find improvements of performance in the navigationof an underwater vehicle with the aid of buoys equipped with GPS receievers.These buoys send positioning data to the vehicle which by using an extendedkalman filter (EKF) fuses this information in order to improve its navigation ability.Another goal with the master thesis has been to create a simulation environmentfor a small underwater vehicle, in which new algorithms or sensors shouldbe able to be integrated easily for various testing. In this assignment this hasresulted in an adaptation of a 6-DOF model to a small underwater vehicle as wellas a regulator design for this system by means of cascade coupled PI regulatorsand gain scheduling. The simulation environment is created within Matlab andSimulink.

<p>Examensarbetets mål är att hitta möjligheter till förbättring av navigeringsprestandahos en undervattensfarkost med hjälp av bojar utrustade med GPS. Dessabojar skickar positionsdata till farkosten som med hjälp av ett extended kalmanfilter(EKF) integrerar denna information till att förbättra sin navigering.Ett ytterligare mål med examensarbetet har även varit att skapa en simuleringsmiljöför en liten farkost, där eventuella nya algoritmer eller sensorer, vidframtida behov, på ett smidigt sätt skall kunna integreras för utprovning. Dettahar i arbetet inneburit en anpassning av en fysikalisk 6-DOF modell till enliten undervattensfarkost samt en reglerdesign för detta system i form av kaskadkoppladePI-regulatorer och parameterstyrning. Simuleringsmiljön är skapad medhjälp av Matlab och Simulink.</p> / <p>The goal of this master thesis is to find improvements of performance in the navigationof an underwater vehicle with the aid of buoys equipped with GPS receievers.These buoys send positioning data to the vehicle which by using an extendedkalman filter (EKF) fuses this information in order to improve its navigation ability.Another goal with the master thesis has been to create a simulation environmentfor a small underwater vehicle, in which new algorithms or sensors shouldbe able to be integrated easily for various testing. In this assignment this hasresulted in an adaptation of a 6-DOF model to a small underwater vehicle as wellas a regulator design for this system by means of cascade coupled PI regulatorsand gain scheduling. The simulation environment is created within Matlab andSimulink.</p>

International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California / The Naval Ocean Research and Development Activity (NORDA) has adapted the Loral Instrumentation Advanced Decommutation system (ADS 100) as a portable maintenance system for one of its remotely deployable buoy systems. This particular buoy system sends up to 128 channels of amplified sensor data to a centralized A/D for formatting and storage on a high density digital recorder. The resulting tapes contain serial PCM data in a format consistent with IRIG Standard 106-87. Predictable and correctable perturbations exist within the data due to the quadrature multiplexed telemetry system. The ADS 100 corrects for the perturbations of the telemetry system and provides the user with diagnostic tools to examine the stored data stream and determine the operational status of the buoy system prior to deployment.

International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California / The Naval Ocean Research and Development Activity (NORDA) has adapted the Loral Instrumentation Advanced Decommutation system (ADS 100) as a portable maintenance system for one of its remotely deployable buoy systems. This particular buoy system sends up to 128 channels of amplified sensor data to a centralized A/D for formatting and storage on a high density digital recorder. The resulting tapes contain serial PCM data in a format consistent with IRIG Standard 106-87. Predictable and correctable perturbations exist within the data due to the quadrature multiplexed telemetry system. The ADS 100 corrects for the perturbations of the telemetry system and provides the user with diagnostic tools to examine the stored data stream and determine the operational status of the buoy system prior to deployment.

Wave tank tests facilitate the understanding of how complex sea conditions influence the dynamics of man-made structures. If a potential deployment location is known, site data can be used to improve the relevance and realism of the test conditions, thus helping de-risk device development. Generally this data is difficult to obtain and even if available is used simplistically due to established practices and limitations of test facilities. In this work four years of buoy data from the European Marine Energy Centre is characterised and simulated at the FloWave Ocean Energy Research Facility; a circular combined wave-current test tank. Particular emphasis is placed on the characterisation and validation processes, aiming to preserve spectral and directional complexity of the site, whilst proving that the defined representative conditions can be effectively created. When creating representative site-specific sea states, particular focus is given to the application of clustering algorithms, which enable the entire spectral (frequency or directional) form to be considered in the characterisation process. This enables the true complex nature of the site to be considered in the data reduction process. Prior to generating and measuring the resulting sea states, issues with scaling are explored, the facility itself is characterised, and emphasis is placed on developing measurement strategies for the validation of directional spectra. Wave gauge arrays are designed and used to characterise various elements of the FloWave tank, including reflections, spatio-temporal variability and wave shape. A new method for directional spectrum reconstruction (SPAIR) is also developed, enabling more effective measurement and validation of the resulting directional sea states. Through comparison with other characterisation methods, inherent method-induced trade-offs are understood, and it is found that there is no absolute favourable approach, necessitating an application specific procedure. Despite this, a useful set of 'generic' sea states are created for the simulation of both production and extreme conditions. For sea state measurement, the SPAIR method is proven to be significantly more effective than current approaches, reducing errors and introducing additional capability. This method is used in combination with a directional wave gauge array to effectively measure, correct, and validate the resulting directional wave conditions. It is also demonstrated that site-specific wave-current scenarios can be effectively re-created, thus demonstrating that truly complex ocean conditions can be simulated at FloWave. This ability, along with the considered characterisation approach used, means that representative site-specific sea states can be simulated with confidence, increasing the realism of the test environment and helping de-risk device development.

The purpose of this research is to provide a better understanding of the physical and social aspects of rip currents in ocean areas that will lead to better forecasts, better governmental policies in beach areas, and ultimately to save lives. A rip current is a nearshore circulation in which breaking waves run up onto the beach then retreat rapidly in deeper channels back toward the sea. Rip currents pose a significant threat to beachgoers and can pull even the strongest swimmers out to sea. The primary factors associated with rip current formation on unarmored beaches are variations in the local beach bathymetry, wind-generated longshore waves of varying height, and lower tidal stages. The rationale for this study is highlighted when rip current deaths are put in context with deaths from other weather related deaths. The average number of rip current deaths per year in the United States is 46 and in the year 2010 rip currents were responsible for 64 deaths which was higher than the deaths associated with lightning, tornadoes, hurricanes and the cold winter during the year. The methodology followed for this study includes a review of demographics from over 500 rip current drowning reports along the Atlantic Ocean, Pacific Ocean and Gulf of Mexico coasts of the United States from 1994-2012. This research indicates that tourists are often victims, and rescuers can become the victims. For each state or sub-state area where rip current drownings are prevalent, an analysis of social aspects, beach areas, and associated ocean and weather patterns was conducted using averaged wind and pressure fields over wave generation areas, buoy data, and tide data. It is important to understand the evolution of these drowning events and seek solutions to mitigate the problem.

This study is about the data analysis of wind speed on sea surface, water temperature, atmospheric temperature, and sea waves observations from four buoy stations (Hua-Lian , Hsin-Chu , E-Luuan-Bi and Kin-Men) that belong to Central Weather Bureau Republic of China and Water Resources Agency, and related researches. The period of this study is in winter and summer from 2001 to 2003. Because of the shelter effect from building or hillocks in land, the wind speed on land is abated and not consistent with that on sea. Comparing data form two island stations ( Dongjido and Lanyu) and four buoy stations, the winds around Taiwan are almost the same. That means the monsoon controls the wind direction in summers and winters. Comparing the quantitative results from different wind speed areas in same period of time, the continuity of sea wind is better than that of land wind, especially best in west Taiwan. Also comparing the changes of wind speed in different atmospheric stability layers, wind is stronger in neural than others. Wind speed distribution also showed wind speeds increased when it is far from land, and sea breeze happened near land within 1-2 kilometer. Sea temperature and wind speed are the factors affecting stability. The diurnal variation of air temperature is greater than that of sea and diurnal variation of sea is more significant during winter. Especially along coastal in Eastern Taiwan, the temperature difference between sea and atmosphere could be greater than 10 ¢J, moreover the wind speed on sea surface in Hua-Lian is slow. Therefore, it caused more unstable on sea surface in Hua-Lian. waves could be classified into two types by wave age: swell and wind sea. Swell means because of passing long fetch, the weave height and wave period are saturated and no longer develop. It can¡¦t reveal the effects of sea wind on waves. Therefore, if swell is the major composition of waves, the inaccuracy of calculated stress would be large. On the contrary, when wind sea is the major composition of waves, roughness could be calculated by wave steepness. While analyzing coefficient of momentum flux on sea surface near Taiwan, gust factor under neutral and unstable conditions had different. Gust factor would change with wind speed under neutral condition, but change with stability under unstable condition. In neutral condition, wind speed and drag coefficient are direct proportion and then correlation among p of power law of wind profile, turbulence intensity and gust factor under neutral condition and strong wind are similar, the value close to 0.1.

While wind energy has witnessed faster growth than any other renewable energy source in recent years, two issues—the decreasing availability of large land expanses for new wind farms and transmission difficulties arising from siting wind farms in remote regions far from load centers—have slowed down this growth considerably. Siting wind turbines offshore places the generating capacity closer to population and load centers; thus, reducing grid congestion. Also, at offshore sites, one can expect higher wind speeds, decreased turbulence, and reduced noise and visual impact constraints. Offshore wind turbines that have been built thus far have had foundations (such as monopiles or jacket structures) that have extended to the seabed. Such offshore wind turbines have thus been confined to shallow waters closer to the shore. Sites farther offshore provide better wind resources (i.e., less turbulence and smoother, stronger winds) while also reducing visual impact, noise, etc. However, deeper waters encountered at such sites make bottom-supported turbines less economical. Wind turbines mounted atop floating platforms are, thus, being considered for deeper water offshore sites. Various floating platform concepts are under consideration; the chief differences among them arise from the way they provide stability to counter the large mass of the rotor-nacelle assembly located high above the mean water level. Of these alternative concepts, the spar buoy platform is a deep draft structure with a low center of gravity, below the center of buoyancy. Reliability analysis of a spar buoy-supported floating offshore 5MW wind turbine based on stochastic simulation is the subject of this study. Environmental data from a selected deepwater reference site are employed in the numerical studies. Using time-domain simulations, the dynamic behavior of the coupled platform-turbine system is studied; statistics of tower and rotor loads as well as platform motions are estimated and critical combinations of wind speed and wave height identified. / text

An oceanographic buoy with 10 atmospheric and oceanographic instruments was deployed in Clayoquot Sound on the west coast of Canada in 2007. The high-resolution time series was used to monitor the fine-scale variability in the coastal ocean. Over 700 CTD profiles measuring temperature, salinity and chlorophyll fluorescence made in the region of the buoy were used to relate the buoy data to spatial patterns. Analysis showed that large-scale upwelling in combination with the localized winds and tidal currents affect water properties at time scales of hours to days. At low tide the buoy represented inland water and at high tide the buoy represented offshore water. Both the buoy data and CTD profiles measured a strong offshore/onshore gradient. For temperature the gradient depended on the direction of the wind, salinity was always higher offshore compared to onshore, and the chlorophyll fluorescence was higher onshore in the early spring and higher offshore for the rest of the time series. The fine scale temporal resolution of the buoy was able to capture the variability measured by the CTD profiles in a 40km2 area. This work shows the importance of making high-resolution temporal measurements in the coastal ocean. However, these types of moorings also require frequent maintenance. In Clayoquot Sound, the optical sensors needed to be cleaned every 4-6 days.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15356号 / 工博第3235号 / 新制||工||1487(附属図書館) / 27834 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 間瀬 肇, 教授 後藤 仁志, 准教授 森 信人 / 学位規則第4条第1項該当