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  • 1.
    Ahlgren, Fredrik
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Waste heat recovery in a cruise vessel2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In three studies of a cruise ship the author has investigated waste heat recovery (WHR)from exhaust gases using an organic Rankine cycle (ORC), and also mapped the energyand exergy flows within the ship. Data were collected from the ship’s machinerysystem for a total extent of one year, and this data were used for simulations andenergy calculations. An off-design analysis was made and an ORC was simulated andoptimised with regards to the ship’s operating conditions. The ORC working fluid wasoptimised in terms for maximum electrical production in the off-design condition. Theoff-design analysis showed that the ship speed and power consumption was far fromits original design. The results indicate that there is a potential for significant savingsby using an organic Rankine cycle for waste heat recovery. The energy and exergyanalysis gave a better understanding of the energy flows and showed that the singlelargest exergy destruction occurs in the ship’s diesel engines.

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  • 2.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Mondejar, Maria E.
    Lund University.
    Genrup, Magnus
    Lund University.
    Thern, Magnus
    Lund University.
    Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study2015In: ASME Turbo Expo 2015: Turbine Technical Conference and Exposition: Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration, Montreal, Quebec, Canada, June 15–19, 2015, ASME Press, 2015, Vol. 3, p. 43392-43416, article id V003T06A018Conference paper (Refereed)
    Abstract [en]

    Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.

  • 3.
    Ahlgren, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Mondejar, Maria E.
    Lund University.
    Genrup, Magnus
    Lund University, Sweden.
    Thern, Marcus
    Lund University, Sweden.
    Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study2016In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, article id 011702Article in journal (Refereed)
    Abstract [en]

    Maritime transportation is a significant contributor to SOx,NOx, and particle matter (PM) emissions, and to a lesser extent, of CO2. Recently, new regulations are being enforced in special geographical areas to limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry toward the improvement of the energy efficiency of ships. Although more sophisticated and complex engine designs can improve significantly of the energy systems on ships, waste heat recovery arises as the most effective technique for the reduction of the energy consump- tion. In this sense, it is estimated that around 50% of the total energy from the fuel con- sumed in a ship is wasted and rejected through liquid and gas streams. The primary heat sources for waste heat recovery are the engine exhaust and coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines (AE) exhaust heat. Experimental data from the engines on the cruise ship M/S Birka Stockholm were logged during a port-to- port cruise from Stockholm to Mariehamn, over a period of 4 weeks. The ship has four main engines (ME) W€artsil€ a 5850kW for propulsion, and four AE 2760kW which areused for electrical generation. Six engine load conditions were identified depending on the ship’s speed. The speed range from 12 to 14 kn was considered as the design condi- tion for the ORC, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene as working fluid would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total elec- tricity consumption on board. These data confirmed the ORC as a feasible and promisingtechnology for the reduction of fuel consumption and CO2 emissions of existing ships.

  • 4.
    Al-Salmi, Ali
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Wintzell, Per
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    En effektiv praktik till sjöss: En studie om hur sjöbefälsstudenter upplever att sömnbrist, kontraktslängd och arbetstider påverkar kunskapsinhämtandet under den fartygsförlagda utbildningen.2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The master mariner students at Kalmar Maritime Academy have twelve months of ship-based training which is a part of the education plan, and these twelve months are distributed over three periods. The internship offers the students the opportunity to practice and develop the theoretical knowledge they have gained in school, but also to experience how it really is to work at sea. The work environment, the social environment and what it can be like to be away from home for a longer period are central. Working at sea has many benefits but also its challenges. The job is associated with long periods at sea with a high workload and high demands on the organization on board, as well as safety and environmental awareness. As a master mariner student at Kalmar Maritime Academy, you end up in this environment during your first year of education when you leave school for the first internship period during semester one. This study aims to investigate how master mariner students experience that lack of sleep, contract length and working hours on board affect their knowledge acquisition. To find out the students' experiences, a qualitative interview study was conducted with six master mariner students; only senior year students were interviewed because they had completed all or a large part of the ship-based training and were therefore considered to have the most experience. The answers were in most cases consistent where the students felt that the internship periods and working days were too long, that they needed to have at least one day off a week and that lack of sleep had a negative impact on their knowledge acquisition. At the same time, the study showed what would be the optimal for the master mariner students' knowledge acquisition, in terms of optimal length of internship periods and optimal work schedule for a rewarding and effective internship as possible. 

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  • 5.
    Amanda, Holmkvist
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics, Byggteknik.
    Inverkan av torktemperatur vid vattenmättning av bruk och betong: Bestämmning av vattenmättnadsgrad och hydraulisk konduktivitet2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today, there is uncertainty about how much the results differ when drying concrete

    at 20, 50 and 105 °C prior to saturation of concrete in order to determine the

    degree of saturation and hydraulic conductivity. Micro-cracks occur when concrete is

    dried at higher temperatures and causes increased hydraulic conductivity. Further, the

    concrete is believed not to be completely saturated if not all the physically bound

    water, so called free water, has been dried out prior to saturation.

    This thesis compares the effect of three different drying temperatures on the

    possibility to saturate concrete with water. The work was conducted at Vattenfall’s

    concrete laboratory in Älvkarleby. The three drying temperatures were +20 °C

    (room temperature), 50 °C and +105 °C. The objective was to determine if

    differences on the degree of saturation and hydraulic conductivity were non-existent

    or negligible. Vacuum saturation after drying at 105 °C is considered to be complete.

    The results after drying at 20 °C and 50 °C were compared to those after drying at

    105 °C. The results of the tests indicate that the concrete should be dried at +105°C

    prior to saturation with water. Then the risk of frost damage to concrete in hydro

    power structures can be assessed.

    How determination of the hydraulic conductivity is affected by the drying

    temperature gave more vague and dubious results. All specimens showed a maximum

    hydraulic conductivity after drying at 50 °C, not after 105 °C as expected. It was

    believed that the hydraulic conductivity theoretically would increase because of

    (more) micro-cracks when being dried at 105 °C. Results from the concrete with vct

    1.0 gave results that indicated that the specimens had been damaged by method 1. To

    sum up, the results of the tests indicate that further studies on the effects of drying

    temperatures should be made.

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    Inverkan av torktemperatur vid vattenmättning av bruk och betong
  • 6.
    Andersen, Jacob
    et al.
    Aalborg University; Denmark.
    Eskilsson, Claes
    Aalborg University, Denmark.
    Detached-Eddy Simulation of Normal Flow past Flat Plates: The Influence from Corner Curvature2023In: International Journal of Offshore and Polar Engineering, ISSN 1053-5381, Vol. 33, no 4, p. 359-366Article in journal (Refereed)
  • 7.
    Andersson, C.
    et al.
    IVL Swedish Environmental Research Institute.
    Johansson, A.T.
    IVL Swedish Environmental Research Institute.
    Genell, A.
    VTI.
    Winroth, J.
    IVL Swedish Environmental Research Institute.
    Fully electric ship propulsion reduces airborne noise but not underwater noise2024In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 302, p. 117616-117616, article id 117616Article in journal (Refereed)
    Abstract [en]

    Electrification of ships offers zero-emission travel and is spreading rapidly, but the relation between electric ship propulsion and noise pollution is not generally understood. Here, three different types of diesel-electric hybrid ferries have been measured in two operating modes: running in hybrid mode with the diesel engine powering an electric generator; and running in fully electric battery powered mode. Measurements were performed to simultaneously quantify airborne and underwater radiated noise. Findings are that on-board diesel engines for electricity generation do not contribute a large extent of the underwater radiated noise, whilst a major source of airborne low-frequency radiation.

  • 8.
    Andersson, C.
    et al.
    IVL Swedish Environmental Research Institute.
    Johansson, A.T.
    IVL Swedish Environmental Research Institute.
    Genell, A.
    VTI.
    Winroth, J.
    IVL Swedish Environmental Research Institute.
    Fully electric ship propulsion reduces airborne noise but not underwater noise2024In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 302, p. 117616-117616, article id 117616Article in journal (Refereed)
    Abstract [en]

    Electrification of ships offers zero-emission travel and is spreading rapidly, but the relation between electric ship propulsion and noise pollution is not generally understood. Here, three different types of diesel-electric hybrid ferries have been measured in two operating modes: running in hybrid mode with the diesel engine powering an electric generator; and running in fully electric battery powered mode. Measurements were performed to simultaneously quantify airborne and underwater radiated noise. Findings are that on-board diesel engines for electricity generation do not contribute a large extent of the underwater radiated noise, whilst a major source of airborne low-frequency radiation.

  • 9.
    Andersson, Kjell
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Engineering Design, System and Component Design.
    Duraisamy, Rimmie
    KTH, School of Industrial Engineering and Management (ITM), Engineering Design, System and Component Design.
    Design Process for Dimensioning Elastomer Bearings for Winch Based Point Absorbers2023In: Proceedings of ASME 2023 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC-CIE 2023, American Society of Mechanical Engineers (ASME) , 2023, article id v002t02a006Conference paper (Refereed)
    Abstract [en]

    Wave energy is a huge power source that can make a significant contribution to the production of renewable energy in the future. It can generate as much as 10% of the world´s present energy consumption [1]. However, Wave Energy Converters (WECs) is a relatively new field, which requires new technology development, and testing before efficient WECs can give any significant contribution to the energy production. The main difficulties lie in the harsh marine environment and the fact that wave power is delivered with high forces and low speeds. The high forces necessitates strong and durable mechanical structures and the slow speed makes efficient energy conversion challenging. Further, there is a very large variation in wave height over time, and during storms, the largest waves can be 10-25 times higher than the average wave height at the site. The maximum forces and motions can thereby be tremendous if not handled properly, and makes the development of efficient Wave Energy Converters (WEC) challenging. The dimensioning forces strongly depend on the wave power concept, the WEC implementation and the actual Power Take-Off (PTO) system. Of the many different types of WECs being researched and developed, this paper focuses on the development of a winch based point absorber wave energy converters (WBPA-WECs). This paper presents the development of a solution for a flexible chain where an elastomeric bearing is used as a means to achieve the relative motion between the links in a chain. With this solution no sliding is present and the motion is achieved as a deformation in the elastomeric bearing. A design process is formulated for determining a suitable configuration of layers of steel shims and elastomers. A test rig for bearing tests has been developed and results from these experimental tests in combination with material tests and FE analysis are presented in the paper. These are presented in the context of illustrating the proposed design process for designing these type of laminated elastomer bearings. The different steps in this design process have been illustrated for the defined test bearing and we can conclude that our findings indicate that the proposed process can be an important support method for further development of this approach with elastomer bearings.

  • 10.
    Andersson, Martin
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Vilka platser ombord löper störst brandrisk: Var startar bränderna ombord2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Fires onboard a seagoing vessel is a very serious accident since you can not rely on shorebased firefighers. The only resource available is the crew and their ability to tackle the situation. Fires can quickly get uncontrollable since there is large amounts of fueloil and even the cargo might be flammable. The purpose with this thesis is to highlight those places onboard that have the greatest risk of fire. So that the crew can either awoid fire or be better prepared if a fire starts.

    The result is based upon data taken from incidentreports from Northern European countries and vessels with length greater than 100m.

    The conclusion that was made is that the engineroom area was the most common place for fires.

    The most common reasons for the fire to start was a leakage of flammable liquid  or electrical failiures.

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  • 11.
    Asplund Schmidt, Johan
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Skyddad plats: En studie i Danmark och Sveriges beredskap att ta emot fartyg i behov av assistans på skyddad plats2022Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The right to seek refuge in port is an old customary right in shipping. In several cases where ships have sought refuge in a port in modern times, ships have been denied. As a result of the Erika, Castor and Prestige incidents around the 21st century, which in two of the cases led to major environmental disasters in the form of oil spills, it was realized that something needed to be done. The IMO drafted its guidelines and EU-drafted Directive 2002/59/EC dealing with the reception of ships in a place of refuge. A place of refuge is defined as a port, part of port or other protective berth or other protected area, such as anchorage, which can be used to receive ships in an emergency or in need of assistance. The purpose of this work is to investigate the preparedness in Sweden and Denmark to receive ships in a place of refuge. which authorities are part of the organization, what decision-making documents exist, what laws and directives are in place and which places of refuge that have been designated in the two countries; In order to get answers to the questions, the study has mainly been carried out through a literature study, but qualitative interview have also been used. The results show that there are guidelines from the IMO that are not legally binding, but also EU directives transposed into the national law of the two countries. The EU also has material intended to facilitate countries to draw up their own contingency plans under Directive 2002/59/EC. Both countries have designated protected sites and a governement structure for receiving ships in a place of refuge but quite different approach. The study shows that it is an important but complex issue. There are many different authorities and stakeholders involved. It is still a work in progress where Sweden is revising its plans at the moment. One current topic seems to be incidents regarding Hazardous and Noxious Substances (HNS) and ratification of the HNS convention.

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  • 12.
    Axelsson, Unnar
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Folkesson, John
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS. KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Underwater feature extraction and pillar mapping2015Report (Other academic)
    Abstract [en]

    A mechanicaly scanned imaging sonar, MSIS, pro-duces a 2D image of the range and bearing of return intensities.The pattern produced in this image depends on the envior-mental feature that caused it. These features are very usefulfor underwater navigation but the inverse mapping of sonarimage pattern to environmental feature can be ambiguous. Weinvestigate problems associated with using MSIS for navigation.In particular we show that support vector machines can be usedto classify the existance and types of feature in a sonar image.We develop a sonar processing pipleline that can be used fornavigation. This is tested on two sonar datasets collected fromROV’s. 1

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    TRAxelsson
  • 13.
    Ayotte, John
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Dynamic positioning of a semi-submersible, multi-turbine wind power platform2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As a growing market for offshore wind power has created a niche for deep-water installations, offshore floating wind solutions have become more and more viable as a renewable energy source. This technology is currently in development and as with many new technologies, many traditional design methods are found lacking. In the multi-turbine platform design investigated, turbine units are placed closely together to conserve material use and reduce cost, however with such tightly spaced turbines; wake interaction poses a threat to the productivity and the lifespan of the installation. In order to fully capitalize on the substantial increase in available wind energy far at sea, it is important that these floating parks operate in an optimal way. The platform investigated in this report sports 3, 6MW turbines which must be positioned such that wake interference is minimized; the platform must always bear a windward heading. 

    Maneuvering ocean going vessels has been practiced using automated dynamic positioning systems in the gas and oil industry for over 50 years, often employing submerged thrusters as a source of propulsion. These systems are mostly diesel powered and require extra operational maintenance, which would otherwise increase the cost and complexity of a floating wind farm. In this paper, it is suggested that the wind turbines themselves may be used to provide the thrust needed to correct the platform heading, thus eliminating the practical need for submerged thrusters. By controlling the blade pitch of the wind turbines, a turning moment (torque) can be exerted on the platform to correct heading (yaw) relative wind direction. Using the Hexicon H3-18MW platform as a starting point; hydrodynamic, aerodynamic and electromechanical properties of the system are explored, modeled and attempts at model predictive control are made. Preliminary results show that it is possible to control the H3’s position (in yaw) relative the wind using this novel method.

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    Dynamic positioning of a semi-submersible, multi-turbine wind power platform
  • 14.
    Baldi, Francesco
    et al.
    Chalmers University of Technology, Sweden.
    Ahlgren, Fredrik
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Nguyen, Tuong-Van
    Technical University of Denmark, Denmark.
    Gabrielii, Cecilia
    Chalmers University of Technology, Sweden.
    Andersson, Karin
    Chalmers University of Technology, Sweden.
    Energy and exergy analysis of a cruise ship2015In: Proceedings of ECOS 2015 - the 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of  Energy Systems, Pau: Pau University , 2015Conference paper (Refereed)
    Abstract [en]

    The shipping sector is today facing numerous challenges. Fuel prices are expected to increase in the medium-long term, and a sharp turn in environmental regulations will require several companies to switch to more expensive distillate fuels. In this context, passenger ships represent a small but increasing share of the industry. The complexity of the energy system of a ship where the energy required by propulsion is no longer the trivial main contributor to the whole energy use thus makes this kind of ship of particular interest for the analysis of how energy is converted from its original form to its final use on board.To illustrate this, we performed an analysis of the energy and exergy flow rates of a cruise ship sailing in the Baltic Sea based on a combination of available measurements from ship operations and of mechanistic knowledge of the system. The energy analysis allows identifying propulsion as the main energy user (41% of the total) followed by heat (34%) and electric power (25%) generation; the exergy analysis allowed instead identifying the main inefficiencies of the system: exergy is primarily destroyed in all processes involving combustion (88% of the exergy destruction is generated in the Diesel engines and in the oil-fired boilers) and in the sea water cooler (5.4%); the main exergy losses happen instead in the exhaust gas, mostly from the main engines (67% of total losses) and particularly from those not equipped with heat recovery devices.The improved understanding which derives from the results of the energy and exergy analysis can be used as a guidance to identify where improvements of the systems should be directed.

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  • 15.
    Baldi, Francesco
    et al.
    Chalmers University of Technology.
    Nguyen, Tuong-Van
    Technical University of Denmark.
    Ahlgren, Fredrik
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    The application of process integration to the optimisation of cruise ship energy systems: a case study2016In: ECOS 2016: 29th International Conference on Efficiency, Cost, Optimization, Simulation and Envirionmental Impact of Energy Systems. June 19-23 2016, 2016Conference paper (Refereed)
    Abstract [en]

    In recent years, the shipping industry has faced an increasing number of challenges in terms of fluctuating fuel prices, stricter environmental regulations, and concerns about global warming. In this situation, passenger volumes on cruise ships have increased from around 4 million to 13 million from 1990 to 2008 and keep growing today. A small cruise ship can emit about 85 tons of CO2 per day, and require around 27 tons of fuel per day. To keep up with market demand, while reducing their impact on the environment, cruise ships will need to improve their energy efficiency. Most previous research in marine technology relates to energy efficiency focused on propulsion, which for most ship types constitutes the largest energy demand. On cruise ships, however, auxiliary heat and electric power also have a significant importance. For this reason, we focus in this paper on the heat demand and its integration with available sources of waste heat on board. In this study, the principles of process integration are applied to the energy system of a cruise ship operating in the Baltic Sea. The heat sources (waste heat from the main and auxiliary engines in form of exhaust gas, cylinder cooling, charge air cooling, and lubricating oil cooling) and sinks (HVAC, hot water, fuel heating) are evaluated based on one year of operational data and used to generate four operating conditions that best represent ship operations. Applying the pinch analysis to the system revealed that the theoretical potential for heat integration on board could potentially allow the reduction of the external heat demand by between 35% and 85% depending on the investigated case. A technoeconomic optimisation allowed the identification of the most economically viable heat exchanger network designs: two in the “retrofit” scenario and one in the “design” scenario, with a reduction of 13-33%, 15-27% and 46-56% of the external heat demand, respectively. Given the high amount of heat being available after the process integration, we also analysed the potential for the installation of a steam turbine for the recovery of the energy available in the exhaust gas, which resulted in up to 900 kW of power being available for on board electric power demand.

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  • 16.
    Baldi, Fransceco
    et al.
    Chalmers University of Technology.
    Ahlgren, Fredrik
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Melino, Francesco
    Universitá di Bologna, Italy.
    Gabrielii, Cecilia
    Chalmers University of Technology.
    Andersson, Karin
    Chalmers University of Technology.
    Optimal load allocation of complex ship power plants2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 124, p. 344-356Article in journal (Refereed)
    Abstract [en]

    In a world with increased pressure on reducing fuel consumption and carbon dioxide emissions, thecruise industry is growing in size and impact. In this context, further effort is required for improvingthe energy efficiency of cruise ship energy systems.In this paper, we propose a generic method for modelling the power plant of an isolated system withmechanical, electric and thermal power demands and for the optimal load allocation of the different componentsthat are able to fulfil the demand.The optimisation problem is presented in the form of a mixed integer linear programming (MINLP)problem, where the number of engines and/or boilers running is represented by the integer variables,while their respective load is represented by the non-integer variables. The individual components aremodelled using a combination of first-principle models and polynomial regressions, thus making thesystem nonlinear.The proposed method is applied to the load-allocation problem of a cruise ship sailing in the Baltic Sea,and used to compare the existing power plant with a hybrid propulsion plant. The results show thebenefits brought by using the proposing method, which allow estimating the performance of the hybridsystem (for which the load allocation is a non-trivial problem) while also including the contribution ofthe heat demand. This allows showing that, based on a reference round voyage, up to 3% savings couldbe achieved by installing the proposed system, compared to the existing one, and that a NPV of11 kUSD could be achieved already 5 years after the installation of the system.

  • 17.
    Bender, Anke
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Francisco, Francisco G. A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Sundberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    A Review of Methods and Models for Environmental Monitoring of Marine Renewable Energy2017In: Proceedings of the 12th European Wave and Tidal Energy Conference, EWTEC , 2017Conference paper (Refereed)
    Abstract [en]

    A continued expansion of the marine renewable energy sector will result in an increased demand in monitoring the natural marine environment. This may be due to a basic scientific interest but is foremost linked to the requirement of pre- and post-construction studies in relation to environmental impact assessments and consenting processes for marine renewable energy projects. With focus on wave and tidal power, but without attempting to provide a comprehensive list, we review methods, technologies and other scientific tools used for monitoring and predicting possible impacts from marine energy installations, on both population and behavioural levels. This includes traditional methods such as fishing gear, like nets and cages, modern technologies such as platforms with multi parameter equipment and the use of deterministic models. This paper is intended to serve as an overview for technology developers as well as authorities, regulators and decision makers with interests in general techniques, and naturally for scientists and consultants commonly being executors of studies and monitoring programs. By giving relevant and up to date references this paper may also be useful for finding more detailed information on study methods and variants. Finally, we give recommendations on where development of technologies is needed in order to face future requirements.

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  • 18.
    Bengtsson, Mattias
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Andersen, Kristian
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Hur dokumenteras blackout ombord på fartyg?: En studie av haverirapporter där blackout var en del av händelseförloppet2014Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    On board vessels it is not desirable to have a power failure, a so-called blackout. The thesis

    has investigated to what extent it is feasible to perform comparative and preventive studies

    with the accident reports from European flag states as a basis. This in order to investigate

    recurring shortcomings, of the vessels or in the work on board that has caused the blackout. In

    addition the possibility to categorize the cases was investigated. The categories were technical

    errors, operational errors and organization errors. Roughly half of the cases show that a single

    category of fault could not be identified due to a combination of faults leading to the blackout.

    However there are recurring cases with almost identical scenarios. For example unsatisfactory

    insulation caused fires due to leaking fuel hitting the hot surfaces.

    The survey shows that there is a lack of symmetry regarding the language used, structure,

    scope and form of publication. It also showed faults in the search engines of the databases.

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    Hur dokumenteras blackout ombord på fartyg?
  • 19.
    Björkman, Robin
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Rehnberg, Olof
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    CV och personligt brev för nyutexaminerade fartygsbefäl i den svenska sjöfartsbranschen2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As the competition for employment toughens amongst deck officers high effort is required in order to stand out from the crowd regarding job applications. The purpose of this study has been to investigate what content the Swedish shipping industry values most in CVs and cover letters. This was achieved by interviewing nine recruiters from different shipping companies and management agencies that recruit Swedish junior officers. A literature search regarding previous studies concerning recruitment provided a wider understanding of the subject and its relevance for maritime science graduates. The literature search also revealed a knowledge gap regarding recruiters in the Swedish shipping industry preferences about CVs and cover letters. The results of the study show some patterns and tendencies amongst the respondents, common to all of which is a preference of short and concise CVs and cover letters with content that is relevant for the applied position. The results also show that a job application is interpreted subjectively and therefore to some extent must be tailored to each individual employment opportunity.

    Download full text (pdf)
    fulltext
  • 20.
    Bosi, Umberto
    et al.
    INRIA Bordeaux Sud-Ouest, France.
    Engsig-Karup, Allan P.
    DTU Technical University of Denmark, Denmark.
    Eskilsson, Claes
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Ricchiuto, Mario
    INRIA Bordeaux Sud-Ouest, France.
    Solai, Elie
    Université de Toulon, France.
    A high-order spectral element unified Boussinesq model for floating point absorbers2018In: Coastal Engineering Proceedings, 2018Conference paper (Refereed)
    Abstract [en]

    Nonlinear wave-body problems are important in renewable energy, especially in case of wave energy converters operating in the near-shore region. In this paper we simulate nonlinear interaction between waves and truncated bodiesusing an efficient spectral/hp element depth-integrated unified Boussinesq model. The unified Boussinesq model treatsalso the fluid below the body in a depth-integrated approach. We illustrate the versatility of the model by predictingthe reflection and transmission of solitary waves passing truncated bodies. We also use the model to simulate themotion of a latched heaving box. In both cases the unified Boussinesq model show acceptable agreement with CFDresults – if applied within the underlying assumptions of dispersion and nonlinearity – but with a significant reductionin computational effort.

  • 21.
    Bram, Staffan
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Burgén, Julia
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Burden, Håkan
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Evakuering av kustnära fartyg i en automatiserad framtid2023Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Den kustnära färjetrafiken är en tacksam miljö för att testa nya automationslösningar. Här finns många fartyg som trafikerar relativt lugna vatten och där bemanningen redan idag är begränsad till en eller två personer. Men förändringar i teknik och bemanning kommer också kräva nya perspektiv i säkerhetsarbetet. I projektet SPECTRUM har besättningens roll vid en nödevakuering undersökts och jämförts med olika automationsscenarier för kustnära färjetrafik. Resultatet pekar ut områden där fortsatt forskning och utveckling är nödvändig för att säkerställa att en evakuering av ett fartyg kan genomföras med så goda förutsättningar som möjligt - om bemanningen reduceras, yrkesroller förändras eller om besättningen ersätts med automationslösningar.

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    fulltext
  • 22.
    Braune, Yann
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Civil and Industrial Engineering, Industrial Engineering and Management.
    Investments in Academic Renewable Electricity Generation Technology Spin-Offs: A Qualitative Study on High Capital Limitations for Underexplored Renewable Energy Sources2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Due to an intensified climate change discourse, renewable energy technologies find higher attention within the energy system and increasingly compete with traditional energy conversion systems. Electricity is progressively being generated through renewable electricity generation technologies (REGT) which harness naturally existing energy fluxes (wind, tide, heat, sun) and convert it to electricity. High investments are currently being made into well-developed REGT using explored energy sources such as wind, hydro or solar. In order to increase cost- and energy efficiency of REGTs, university research projects are developing new REGTs that harvest underexplored energy sources such as the marine energy source. These capital-intensive marine energy research projects are entering the market through university spin-off firms but are often confronted with funding gaps, for the current or future operations. Capital rich investors could provide these funds but are often investing in well explored energy sources rather than into underexplored but more cost- and energy-efficient energy sources. Utilizing a qualitative, grounded theory-influenced approach and combining empirical material of semi-structured interviews, data from a participant observation of an innovation system workshop attendance and data from continuous meetings with an academic REGT spin-off from Uppsala University, this study investigates 1) the drivers and barriers within the funding ecosystem for academic REGT spin-offs in Sweden, 2) the limited access of high capital to underexplored energy sources on the specific case of the marine energy source and 3) a potential common ground for investors with high capital and academic REGT spin-offs in order to allow an accelerated diffusion of the marine energy source. The results indicate that the physical properties of the underexplored marine source should not be accounted for as driver but rather as the foundation of an academic REGT spin-off. This frame allows to bridge practitioners of both the investment field and the academic field of REGT spin-offs through the degree of utilization. An inversion of relations, where not only entrepreneurs increasingly link their field of study to economy and business, but also investors adapt cross-disciplinary knowledge towards academia and natural sciences via the degree of utilization, could be beneficial for an accelerated diffusion of academic REGTs. Bridging practitioners of both fields through the degree of utilization and other means might together with a full commercial application and proof of marine REGTs reduce the funding gap of academic spin-offs in the marine sector and allow access to investors with high capital.

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    Investments in Academic Renewable Electricity Generation Technology Spin-Offs (2020)
  • 23.
    Brynolf, Selma
    et al.
    Chalmers.
    Grahn, Maria
    Chalmers.
    Hansson, Julia
    IVL Swedish Environmental Research Institute.
    Korberg, Andrei David
    Aalborg University.
    Malmgren, Elin
    Chalmers.
    Sustainable fuels for shipping2022In: Sustainable Energy Systems on Ships, p. 403-428Article in journal (Refereed)
  • 24.
    Bävermalm, Joakim
    Linnaeus University, Faculty of Science and Engineering, Kalmar Maritime Academy.
    Antifoulingfärger: Beväxning och ytråhetens inverkan på fartygsekonomin2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Med anledning av dagens höga bunkerpriser är det relevant att undersöka vad man kan göra för att minska bunkerförbrukningen ombord. En viktig del vad gäller bunkerbesparingar är att hålla skrovets kondition i gott skick. Här har ett klokt val av antifoulingfärg en stor betydelse, med en bra antifoulingfärg minskar beväxningen av organismer på skrovet. Detta i sin tur leder till ett minskat motstånd, vilket gynnar fartygsekonomin.

    På marknaden finns flertalet antifoulingfärger tillgängliga, men vilken effekt på ytråheten har respektive färg, och hur påverkar ytråhet i form av beväxning fartyget ekonomiskt? Utöver de rent ekonomiska aspekterna ville jag ta reda på om det finns något miljövänligare alternativ, samt hur det står sig gentemot de biocidbaserade antifoulingfärgerna.

    För att svara på detta har en mängd data studerats från bland annat produktdatablad, fartygskonstruktionsböcker, tidsjournaler och hemsidor. Jag konstaterade att det finns mycket pengar att spara på rätt val av antifouling. Något som förvånade mig var att färgtillverkarens miljövänligaste alternativ också var den effektivaste antifoulingen.

  • 25.
    Carlson, Johan
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Ljung, Johannes
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Efter sjökaptensexamen: 2010-talets sjöbefäl i arbetslivet2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on study of the employment market for graduates from the Master Mariner degree that graduated in 2010, 2013 and 2016. It is a comparison between the three years of graduation within two Swedish universities that offer the Master Mariner programme. Data collection with combined quantitative and qualitative techniques within a mixed-mode study. Results show a majority occupied within the maritime sector, although vessel-based employment has decreased compared to past studies and redundancy is an emerging element. The percentage occupied within the vessel-based sector is higher in Kalmar Maritime Academy, Linnaeus University, compared to Chalmers University, the results from which show a higher concentration in shore-based occupation. The conclusion of this thesis is that the employment market for graduates from maritime institutions in Sweden is undergoing change. 

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    Efter sjökaptensexamen
  • 26.
    Carlén, Camilla
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Sandgathe, Ulrica
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Ackumulatorer som räddar liv: En livscykelkostnadsanalys om UPS som nödkraftkälla2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The SOLAS regulations for merchant vessels states that in the event of loss of power, a backup power supply will start automatically. This paper investigated the possibility to replace the widely-used generator driven by a fossil-fuel powered internal combustion engine, with a UPS. Focus of the investigation included regulations concerning the use of accumulators onboard, market product range fulfilling the legal requirements and price difference based on purchase price and maintenance costs for 25 years. The cost results where compared as a Life Cycle Cost calculation. Regulations by the Swedish transport agency and the Classification DNV-GL allow the use of emergency power from accumulators or generator.

     

    For the possibility to investigate through cost estimations, a theoretical model of a merchant vessel with Swedish flag, was set up. All companies contacted were Swedish manufacturer. The results in the LCC show the situation of today and lets us know that the most cost efficient investment is the conventional emergency generator.

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    Asrl2017
  • 27.
    Carpman, Nicole
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Marine Current Resource Assessment: Measurements and Characterization2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increasing interest in converting energy from renewable resources into electricity has led to an increase in research covering the field of marine current energy, mainly concerning tidal currents and in-stream tidal turbines. Tides have the advantage of being predictable decades ahead. However, the tidal resource is intermittent and experiences local variations that affect the power output from a conversion system. The variability is mainly due to four aspects: the tidal regime, the tidal cycle, bathymetry at the site and weather effects. Each potential site is unique, the velocity flow field at tidal sites is highly influenced by local bathymetry and turbulence. Hence, characterizing the resource requires careful investigations and providing high quality velocity data from measurement surveys is of great importance. In this thesis, measurements of flow velocities have been performed at three kinds of sites.

    A tidal site has been investigated for its resource potential in one of all of the numerous fjords in Norway. Measurements have been performed to map the spatial and temporal variability of the resource. Results show that currents in the order of 2 m/s are present in the center of the channel. Furthermore, the flow is highly bi-directional between ebb and flood flows. The site thus have potential for in-stream energy conversion. A model is proposed that predicts peak current speed from information on tidal range at the site. A corresponding model can be set up and implemented at other similar sites affected by tides, i.e. fjord inlets connecting the ocean to a fjord or a basin.

    A river site serves as an experimental site for a marine current energy converter that has been designed at Uppsala University and deployed in Dalälven, Söderfors. The flow rate at the site is regulated by an upstream hydrokinetic power plant nearby, making the site suitable for experiments on the performance of the vertical axis turbine in its natural environment. The turbine has been run in uniform flow and measurements have been performed to characterize the extent of the wake.

    An ocean current site was a target of investigation for its potential for providing utilizable renewable energy. A measurement campaign was conducted, mapping the flow both spatially and temporally. However, the site was shown to not be suitable for energy conversion using present technique.

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  • 28.
    Carpman, Nicole
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Measurements of tidal current velocities in the Folda fjord, Norway, with the use of a vessel mounted ADCP2014In: 33Rd International Conference On Ocean, Offshore And Arctic Engineering, 2014, Vol 8A: Ocean Engineering, 2014Conference paper (Refereed)
    Abstract [en]

    Measurements of tidal current water velocities is an important first step in evaluating the potential for a tidal site to be used as a renewable energy resource. For this reason, on site measurements are performed at the inlet of a fjord situated at the coast of Norway. The site has an average width of 580 m and adepth of 10-15 m which is narrow and shallow enough to give rise to water velocities that can be of use for energy conversion. With the use of an Acoustic Doppler Current Profiler (ADCP) cross-section measurements are conducted along four transects. The measurements covered flood and ebb currents around one tide and the data give a first approximation of the magnitude and distribution of the flow field. Depth averaged mean current velocities are calculated along the transects for horizontal bins with sizes in the order of 50 x 50 m. Maximum mean velocity for the flood currents were 1.31 m/s and 1.46 m/s for the ebb currents. The measurements show that even a small amount of data can give an indication of the potential and characteristics ofthe site.

  • 29.
    Carpman, Nicole
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thomas, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Tidal current phasing along the coast of Norway2016Conference paper (Refereed)
    Abstract [en]

    Tidal currents provide an intermittent source of renewable energy. A high degree of intermittency is unfavorable in the existing power system. However, by aggregating tidal power from sites with variable tidal phase a more firm power outpu tmay be achieved. In this paper, the tidal current phasing between 114 potential tidal energy sites along the Norwegian coast is investigated. Time series of tidal currents are generated with a model that considers the variation in current strength due to the variability in the semi-diurnal tidal cycle (spring to neap, flood to ebb, first to second daily tide etc.). From these, available kinetic energy in the natural flow is calculated. A constant conversion rate is then applied to give the power output at each site. Three scenarios, with varying number of sites and energy extraction, are investigated. The variability in each scenario is quantified on different time scales by filtering the aggregated power and calculate standard deviation and step change. It is found that the variability can be lowered by choosing sites with an advantageous time lag and limit the power output from the most energetic sites. As expected, smoothing is most distinct on short time scales.

  • 30.
    Castellucci, Valeria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Strömstedt, Erland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Sea level variability in the Swedish Exclusive Economic Zone and adjacent seawaters: influence on a point absorbing wave energy converter2019In: Ocean Science, ISSN 1812-0784, E-ISSN 1812-0792, Vol. 15, p. 1517-1529Article in journal (Refereed)
    Abstract [en]

    Low-frequency sea level variability can be a critical factor for several wave energy converter (WEC) systems, for instance, linear systems with a limited stroke length. Consequently, when investigating suitable areas for deployment of those WEC systems, sea level variability should be taken into account. In order to facilitate wave energy developers finding the most suitable areas for wave energy park installations, this paper describes a study that gives them additional information by exploring the annual and monthly variability of the sea level in the Baltic Sea and adjacent seawaters, with a focus on the Swedish Exclusive Economic Zone. Overall, 10 years of reanalysis data from the Copernicus project have been used to conduct this investigation. The results are presented by means of maps showing the maximum range and the standard deviation of the sea level with a horizontal spatial resolution of about 1 km. A case study illustrates how the results can be used by the WEC developers to limit the energy absorption loss of their devices due to sea level variation. Depending on the WEC technology one wants to examine, the results lead to different conclusions. For the Uppsala point absorber L12 and the sea state considered in the case study, the most suitable sites where to deploy WEC parks from a sea level variation viewpoint are found in the Gotland basins and in the Bothnian Sea, where the energy loss due to sea level variations is negligible.

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  • 31.
    Cederlöw, Jonatan
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Drönares praktiska tillämpning för leveranser till fartyg2022Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study aims to investigate the extent to which the function of drones can be adapted to deliveries of goods to vessels. This study was conducted in the form of interview studies. The study concerns the economic gain of supply deliveries with drones compared to the provisioning vessels, that otherwise carry out this payload as well as the aspects that deal with the drone operator´s impact on this type of service. The study concluded that the drone can be used as a complement and that the technology available on the market is sufficient to be able to safely carry out these deliveries to vessels using drones as aids. Furthermore, the study showed that according to the interviewed drone operators, it is still unclear to what extent the drone will be applied as there are few drones that are tailored for this specific purpose, but that the implementation of drones as a tool at sea is still viewed positively.

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  • 32.
    Chatzigiannakou, Maria A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Temiz, Irina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Mooring types of point absorbing wave energy converters2021In: European Wave and Tidal Energy Conference, EWTEC 2021, 2021Conference paper (Refereed)
  • 33.
    Chatzigiannakou, Maria Angeliki
    et al.
    Uppsala University, Dept. of Electrical Engineering, Uppsala, Sweden.
    Potapenko, Tatiana
    Uppsala University, Dept. of Electrical Engineering, Uppsala, Sweden.
    Ekergård, Boel
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Temiz, Irina
    Uppsala University, Dept. of Electrical Engineering, Uppsala, Sweden.
    Numerical analysis of an Uppsala University WEC deployment by a barge for different sea states2020In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 205, article id 107287Article in journal (Refereed)
    Abstract [en]

    Wave energy converters (WECs) have been deployed onshore, nearshore, and offshore to convert ocean wave movement into electricity. The exploitation of renewable energy sources has restrictions; in the case of wave energy, high installation, maintenance, and decommissioning costs have limited their commercial use. Moreover, these offshore operations can be compromised by safety issues. This paper draws attention to offshore operation safety of a WEC developed by Uppsala University. Specifically, this paper investigates what sea states are suitable for the safe deployment of a WEC from a barge. This study follows recommendations in DNV-RP-H103 for analysis of offshore operations, namely lifting through the wave zone. ANSYS Aqwa is used to find hydrodynamic forces acting on a typical barge, using frequency domain analysis. Based on these hydrodynamic simulation results and methodology given in DNV-RP-H103, tables are created to show the sea states that would allow for the safe installation of a WEC using a typical barge. Considered sea states have significant wave heights varying between 0 m and 3 m and the wave zero crossing periods varying between 3 s and 13 s. The WEC submersions are considered between 0 m and 7 m, i.e. when the WEC is in the air until it is fully submerged. © 2020 Elsevier Ltd

  • 34.
    Chatzigiannakou, Maria Angiliki
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Dolguntseva, Irina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Offshore Deployments of Wave Energy Converters by Seabased Industry AB2017In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 5, no 2, article id 15Article in journal (Refereed)
    Abstract [en]

    Since 2008, Seabased Industry AB (SIAB) has manufactured and deployed several units of wave energy converters (WECs) of different design. The WECs are linear generators with point absorber buoy systems that are placed on the seabed, mounted on a gravitation concrete foundation. These deployments have taken place in different areas, using different deployment vessels. Offshore deployments of WECs and underwater substations have so far been complicated procedures, that were both expensive and time-consuming. The focus of this paper is to discuss these deployments in terms of economy and time efficiency, as well as safety. Because seven vessels have been used to facilitate the deployments, an evaluation on the above basis is carried out for them. The main conclusions and certain solutions are presented for the various problems encountered during these deployments and the vessel choice is discussed. It is found that the offshore deployment process can be optimized in terms of cost, time efficiency and safety with a careful vessel choice, use of the latest available technologies and detailed planning and organizing.

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    fulltext
  • 35.
    Cheemakurthy, Harsha
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Framework for holistic design of ferries focusing on lightweight ice going hulls.2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Waterborne public transportation (WPT) is slowly increasing in importance as an active component of public transportation networks in cities. City planners are looking at WPT to overcome urban congestion and pollution. However, prevalent challenges like ferry procurement, poor state of existing ferry fleets and technical challenges like the presence of ice, have created reluctance in the minds of public transport providers (PTPs).  While contemporary research shows ferries can be economical and environmentally friendly, there are some fundamental challenges that need to be addressed before PTPs can feel confident.

    In this regard, deterrents from PTP’s perspective are identified and solutions are investigated, starting with a systematic characterization of WPT. A definite structure for operational requirements is proposed in an objective manner. Using these as basis, two standard ferry sizes that could fulfil multiple WPT roles in majority of cities are introduced. For establishing city-wise tailoring, platform-architecture based modularization of ferries is proposed. The ferry modules are tailored with respect to operational requirements in a clear and objective manner through the introduction of an evaluation methodology. The method incorporates economic, social, environmental, and regulatory stakeholders. These proposed solutions are aimed at improving PTP’s confidence in WPT and provides solutions for the marine industry to produce quick, cost efficient and tailored ferries. 

    Next, the scope is focused towards investigating sustainable operations in freshwater ice conditions, typically found in the Stockholm region in Sweden. The ice going ferries today operate with ice strengthened heavy hulls. While they work well in ice, they perform poorly in comparison with non-ice going ferries during ice free months. Correspondingly, solutions towards lightweight ice going hulls are investigated. 

    This investigation starts with understanding ice-hull interaction mechanisms. Then, techniques to estimate the ice loads are investigated. We adopt a probabilistic approach to tackle the limitations due to the stochastic nature of ice and a lack of experimental data. The resulting load cases are used for evaluating lightweight structural concepts. 

    The investigation is approached by dividing ice-hull interaction into quasi-static, dynamic and abrasive loading phases. Several candidates corresponding to the first two loading phases are investigated parametrically. The range of structural concepts include metal grillages, bio-inspired composites, and sandwich structures. Realistic loading models for quasi-static and impact mechanisms are developed and validated with experiments. The winning candidates for each loading phase are combined to propose a tri-layer lightweight structural concept. Three candidates for the concept are evaluated and compared.

    The thesis answers several questions that riddle WPT today. But at the same time, it raises new questions. Several directions for future work are identified. With continued development, it would be possible to see modularly tailored ferries operating with lightweight hulls in WPT systems around the world.

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    Kappa
  • 36.
    Cheemakurthy, Harsha
    KTH, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Framework for holistic design of ferries focusing on lightweight ice going hulls.2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Waterborne public transportation (WPT) is slowly increasing in importance as an active component of public transportation networks in cities. City planners are looking at WPT to overcome urban congestion and pollution. However, prevalent challenges like ferry procurement, poor state of existing ferry fleets and technical challenges like the presence of ice, have created reluctance in the minds of public transport providers (PTPs).  While contemporary research shows ferries can be economical and environmentally friendly, there are some fundamental challenges that need to be addressed before PTPs can feel confident.

    In this regard, deterrents from PTP’s perspective are identified and solutions are investigated, starting with a systematic characterization of WPT. A definite structure for operational requirements is proposed in an objective manner. Using these as basis, two standard ferry sizes that could fulfil multiple WPT roles in majority of cities are introduced. For establishing city-wise tailoring, platform-architecture based modularization of ferries is proposed. The ferry modules are tailored with respect to operational requirements in a clear and objective manner through the introduction of an evaluation methodology. The method incorporates economic, social, environmental, and regulatory stakeholders. These proposed solutions are aimed at improving PTP’s confidence in WPT and provides solutions for the marine industry to produce quick, cost efficient and tailored ferries. 

    Next, the scope is focused towards investigating sustainable operations in freshwater ice conditions, typically found in the Stockholm region in Sweden. The ice going ferries today operate with ice strengthened heavy hulls. While they work well in ice, they perform poorly in comparison with non-ice going ferries during ice free months. Correspondingly, solutions towards lightweight ice going hulls are investigated. 

    This investigation starts with understanding ice-hull interaction mechanisms. Then, techniques to estimate the ice loads are investigated. We adopt a probabilistic approach to tackle the limitations due to the stochastic nature of ice and a lack of experimental data. The resulting load cases are used for evaluating lightweight structural concepts. 

    The investigation is approached by dividing ice-hull interaction into quasi-static, dynamic and abrasive loading phases. Several candidates corresponding to the first two loading phases are investigated parametrically. The range of structural concepts include metal grillages, bio-inspired composites, and sandwich structures. Realistic loading models for quasi-static and impact mechanisms are developed and validated with experiments. The winning candidates for each loading phase are combined to propose a tri-layer lightweight structural concept. Three candidates for the concept are evaluated and compared.

    The thesis answers several questions that riddle WPT today. But at the same time, it raises new questions. Several directions for future work are identified. With continued development, it would be possible to see modularly tailored ferries operating with lightweight hulls in WPT systems around the world.

    Download full text (pdf)
    Framework for holistic design of ferries focusing on lightweight ice going hull
  • 37.
    Cheemakurthy, Harsha
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Naval Systems.
    Garme, Karl (Contributor)
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Urban waterborne public transport systems: An overview of existing operations in world cities2017Report (Other academic)
    Abstract [en]

    This report aims to collate information on existing waterborne public transport systems in order to provide a resource for cities that may be considering implementing a water transit network. Stockholm City Council has recently expressed interest in expanding its existing inland waterway network to facilitate increased passenger transport capacity within the city and surrounding districts. This report introduces waterway public transportation systems currently operating in 23 cities around the world to provide an overview of the current state of urban water transit globally. Key operational metrics have been identified and described which have been chosen in order to be most relevant in assessing water transport options for cities. Information regarding system organization, route structure, schedules, and vessels have been compiled. In addition, operational factors contributing to the success of existing water transit systems have also been highlighted as per existing literature. Such characteristics introduced in the report overview include transport integration within the wider public transport network, public perception and feasibility of implementation, land use implications, and the role of water transport in tourism and leisure travel. Efforts toward incorporating environmental sustainability are also briefly addressed. Cities have been divided into three broad categories based on the geographic size and passenger carrying capacity of each water transit system. There were 13 cities identified as large scale, 6 as medium scale and 4 as small scale, or in nascent stages of development. Facilities on board vessels and also terminal infrastructure are compared, as well as any unique features or operating characteristics, which are highlighted. Finally, the systems are mapped a scale in order to compare route structures and scope of operation.

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  • 38.
    Cheemakurthy, Harsha
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Burman, Magnus
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Garme, Karl
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    A lightweight ice going hull concept for freshwater ice operationsManuscript (preprint) (Other academic)
    Abstract [en]

    A fundamental challenge in ice-prone waterborne public transportation systems is the need for ice-strengthening while being fuel efficient during ice-free periods. To achieve this, the use of lightweight hull structures is explored in the current study by starting with introducing a tri-layer structural concept for an ice going hull. The three layers correspond to abrasion loads, impact loads and pressure loads experienced during a typical ice-hull interaction. Several structural concepts suited towards these respective loading mechanisms are considered. Most favorable parametric variants are identified and assembled as contenders in the tri-layer concept. The assembly is tested against experimentally validated ice impact models in FEA as well as a realistic quasi-static pressure representation. Three different lightweight structural concepts including aluminum grillage, stiffened sandwich structure and metal-FRP stiffened sandwich structure are compared and discussed. It is found that the latter of the three concepts is suited best towards both quasi-static and impact loading. Ice going ferries built with ice strengthened lightweight hulls can reduce emissions, fuel consumption as well as increase the payload capacity. Such a ferry would be competitive with non-ice going ferries during ice free periods.

  • 39.
    Chen, WenChuang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Tsinghua Univ, State Key Lab Hydrosci & Engn, Beijing 100084, Peoples R China..
    Dolguntseva, Irina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Savin, Andrej
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Zhang, YongLiang
    Tsinghua Univ, State Key Lab Hydrosci & Engn, Beijing 100084, Peoples R China..
    Li, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Svensson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Numerical modelling of a point-absorbing wave energy converter in irregular and extreme waves2017In: Applied Ocean Research, ISSN 0141-1187, E-ISSN 1879-1549, Vol. 63, p. 90-105Article in journal (Refereed)
    Abstract [en]

    Based on the Navier-Stokes (RANS) equations, a three-dimensional (3-D) mathematical model for the hydrodynamics and structural dynamics of a floating point-absorbing wave energy converter (WEC) with a stroke control system in irregular and extreme waves is presented. The model is validated by a comparison of the numerical results with the wave tank experiment results of other researchers. The validated model is then utilized to examine the effect of wave height on structure displacements and connection rope tension. In the examined cases, the differences in WEC’s performance exhibited by an inviscid fluid and a viscous fluid can be neglected. Our results also reveal that the differences in behavior predicted by boundary element method (BEM) and the RANS-based method can be significant and vary considerably, depending on wave height.

  • 40.
    Coslovich, Franciesco
    et al.
    Chalmers University of Technology, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Östberg, Magnus
    Flowtech International AB, Sweden.
    Janson, Carl-Erik
    Chalmers University of Technology, Sweden.
    Added resistance, heave and pitch for the KVLCC2 tanker using a fully nonlinear unsteady potential flow boundary element method2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 229, article id 108935Article in journal (Refereed)
    Abstract [en]

    In this paper, a fully nonlinear unsteady potential flow method is used to predict added resistance, heave and pitch for the KVLCC2 hull in regular head waves at design speed. The method presents a nonlinear decomposition of the velocity potential and the wave field and an adaptive grid refinement. A formulation for the acceleration potential is used to obtain the pressure. To improve computational efficiency, a Barnes-Hut algorithm is introduced. A grid dependency study and a study on the impact of different time steps on the solution are performed. Numerical results have been compared with experimental data for the design speed. A general good agreement is found for added resistance, especially for longer waves. Heave and pitch are properly computed for all wave lengths in the range λ/Lpp=0.4 to 1.4. © 2021 The Author(s)

  • 41.
    Crespo, Alejandro J.
    et al.
    Universidade de Vigo, Spain.
    Tagliafierro, Bonaventura
    Universidade de Vigo & UPC, Spain.
    Martınez-Estevez, Ivan
    Universidade de Vigo, Spain.
    Domınguez, Jose M.
    Universidade de Vigo, Spain.
    deCastro, Maite
    Universidade de Vigo, Spain.
    Gómez-Gesteira, Moncho
    Altomare, Corrado
    Brito, Moises
    Bernardo, Francisco
    Ferreira, Rui M.
    Capasso, Salvatore
    Viccione, Giacomo
    Quartier, Nicolas
    Stratigaki, Vasiliki
    Troch, Peter
    Simonetti, Irene
    Cappietti, Lorenzo
    Göteman, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Engström, Jens
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
    Clemente, Daniel
    Rosa-Santos, Paulo
    Taveira-Pinto, Francisco
    Bacelli, Giorgio
    Coe, Ryan
    Fourtakas, Georgios
    Rogers, Benedict
    The University of Manchester, UK.
    Stansby, Peter
    The University of Manchester, UK.
    On the state-of-the-art of CFD simulations for wave energy converters within the open-source numerical framework of DualSPHysics2023In: Proceedings of the 15th European Wave and Tidal Energy Conference, Bilbao, 3-7 September 2023, European Wave and Tidal Energy Conference , 2023Conference paper (Refereed)
    Abstract [en]

    There are currently several types of devices capable of harnessing wave energy, exploiting a broad variety of physical transformation processes. These devices – known as Wave Energy Converters (WECs) – are developed to maximize their power output. However, there are still uncertainties about their response and survivability to loads induced by adverse environmental conditions, with a consequent increase of the Levelized Cost of Energy (LCOE), which prevents in fact their commercial diffusion. As evidenced by a large body of research, marine renewable energy devices need to have more robust design practices. To address this issue, we propose the CFD-based DualSPHysics toolbox as a support in the design stages. DualSPHysics is high-fidelity software inherently suited to numerically address most challenges posed by multiphysics simulations, which are required to reliably predict WEC response in situations well beyond operational conditions. It should be noted that WECs, generally, may be connected to the seabed and comprise mechanical systems named Power Take-Offs (PTO) used to convert the energy from waves into electricity or other usable energies. To reproduce these features, DualSPHysics benefits from coupling with the multiphysics library Project Chrono and the dynamic mooring model Moordyn+. In this work, the augmented DualSPHysics framework is utilised to simulate a range of very different types of WECs with a variety of elements, such as catenary connections, taut mooring lines, or linear and nonlinear PTO actuators. Version 5.2 of the open-source licensed code was recently released, making the numerical framework publicly available as one unit. This work aims to provide a numerical review of past applications, and to demonstrate how the same open-source code is able to simulate very different technologies.

    Specifically, this paper proposes routine modeling and validation procedures using the SPH-based solver DualSPHysics applied to five different WEC types: i) a moored point absorber (PA); ii) an oscillating wave surge converter (OWSC); iii) a floating OWSC (so called FOSWEC); iv) a wave energy hyperbaric converter (WEHC); and v) a multi-body attenuator (so called Multi-float M4). For each device listed above, we provide validation proof against physical model data for various components of the floater(s) and PTO related quantities, performed under specific sea conditions that aim to challenge their survivability. Within the scope of this research, we present the WEC response with respect to the degrees of freedom that really matter for each of the floatings due to hydrodynamic interactions (i.e., heave, surge, and pitch), along with quantities more intimately connected to the anchoring systems (e.g., line tension) or the mechanical apparatus (e.g., end-stopper force). The quality of the results, the discussion built upon them and the demonstrated solver exploitability to a wide range of WECs show that one software model can run all cases using the exact same methodology, which is of great value for the marine energy R&D community. Finally, we discuss future research objectives, which include the implementation of automation to apply open control systems and possible applications to subsets of WEC farm arrays and other floating energy harnessing devices.

  • 42.
    Dahlin, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Gustavsson, Richard
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Brandskyddet i Göteborgs Hamn AB:s Energihamn: Ett projektarbete i fallstudieform för Göteborgs Hamn AB, som undersöker vilka förväntningar personal vid rederier och fartygsbefäl har på brandskyddet i Energihamnen, en hamnanläggning i Göteborgs Hamn AB.2014Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    This thesis is part of a major project that the Port of Gothenburg has embarked upon, and is produced as a result of a project directive. The purpose of that project is to renew its current fire protection in Energihamnen (the Energy Port) but also meet future requirements. The purpose of the present study is to examine what expectations shipping companies and ship´s officers, which regularly arrive to the Energy Port, have on the Port of Gothenburg’s fire prevention systems and fire emergency plans. Further investigated are the requirements that form the basis for the fire protection equipment onboard tankers that regularly arrive in the Energy Port. To obtain answers from the above mentioned purpose, interviews were conducted with three ship owners and five ship officers, and this was combined with a literature summary which consists of the regulatory framework that places specific requirements and recommendations for the fire prevention equipment that will be on board tankers. The interviews were conducted to include the shipping industry's expectations of the Port of Gothenburg’s emergency procedures during cargo operations. The result shows that the majority of respondents expected that the Port of Gothenburg should have firefighting equipment on their docks that can extinguish fires onboard the ship’s deck. They also expected that the port's emergency response plans should be well rehearsed and should also quickly come into force during an emergency.

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    Brandskyddet i Göteborgs Hamn AB:s Energihamn
  • 43.
    Dannelind, Filip
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Hydrogen on demand for vessels: Using ammonia for hydrogen storage2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of an ammonia and hydrogen mixture in an internal combustion engine has previously been tested.  Limited number of studies have been done on how such a system efficiently can be adopted onboard a vessel and remain competitive to today’s fossil power solutions. A literature study was done to evaluate different aspect of the study such as what concentrations of ammonia and hydrogen that could be usable for an internal combustion engine, what storage tanks that could be used and how the reforming process could be optimized. 

    The study showed that in order for an ammonia and hydrogen on demand power/fuel system to be competitive, focus must be on how to minimize the external thermal input to the system and using a beneficial storage method for the specific vessel. The system has a cold side in which thermal energy is needed and a hot side in which thermal heat needs to be dissipated, comparing option 1-3 shows that managing these two sides of the system greatly increased the efficiency. 

    The study also shows that having an increased hydrogen mixture above   might be deemed unnecessary since it increases the cracker size needed and amount of ammonia tap off from both the main-stream and combustion-stream. Further investigations are needed on how to optimize the schematical design of the system if the temperature of the mixed-stream is deemed to be too high for the engine, this heat could then be utilized in another part of the cold side of the system.

    The full text will be freely available from 2025-05-25 13:00
  • 44.
    Dashtimanesh, Abbas
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. Tallinn University of Technology, Estonian Maritime Academy, Tallinn, Estonia.
    Ghaemi, Mohammad Hossein
    Wang, Youjiang
    Karczewski, Artur
    Bilandi, Rasul Niazmand
    Hirdaris, Spyros
    Digitalization of High Speed Craft Design and Operation Challenges and Opportunities2022In: Procedia Computer Science, ISSN 1877-0509, Vol. 200, p. 566-576Article in journal (Refereed)
    Abstract [en]

    In recent years, global demands for safe and sustainable ships led to dramatic changes in maritime industry. Digitalization is expected to play important part in the future. This is supported by analysis of the autonomous ships market which shows that digitalization of large ship types such as tankers and container ships is well on track. Although to date designs of autonomous High Speed Craft (HSC) have been developed, there are only a few studies on the impact of digitalization on design and operations. This is because of the challenging operational profile of these assets across a spread of waterborne activities namely fishing, leisure, patrolling and rescuing. This paper reviews literature of relevance on the potential of digitalization of the HSC sector in the Baltic. An overview of the systems that could be partly digitalized and how technology developments may influence operations are also outlined.

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  • 45.
    Davidsson, Lo
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Andersson Wodlén, David
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Interaction i Kielkanalen: En undersökning av de bakomliggande orsakerna till olyckor orsakade av interaction i Kielkanalen2021Independent thesis Basic level (professional degree), 10 HE creditsStudent thesis
    Abstract [en]

    Most of the accidents at sea occurs in coastal or inner waterways, often with a dense traffic situation. This study investigates accidents in the Kiel canal caused by interaction. Even though the risks of hydrodynamic impact in traffic densed fairways are well known, accidents still occurs. The study consists of five reports, chosen from the german accident investigation board, which have been examined qualitatively with the analysis method HFACS-MA. By mapping the different underlying causes and with the help of a casual chain also identifying the cause categories behind each accident. Hopefully, by identifying and highlighting  the causes behind the accidents, this will prevent similar accidents to occur in the future. The study showed that the main causes behind these accidents were lack of communication or human interaction and insufficient surveillance of the traffic together with badly planned operations. The results showed some structurally deficiencies that authorities could improve upon. The study showed that knowledge and risk assessment for nautical officers and captains, pilots and vts-operators together with legislation or reviews of regulations on authority level, could reduce the risks of this type of accidents.

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  • 46.
    Davidsson, Lo
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Andersson Wodlén, David
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Interaction i Kielkanalen: En undersökning av de bakomliggande orsakerna till olyckor orsakade av interaction i Kielkanalen2021Independent thesis Basic level (professional degree), 10 HE creditsStudent thesis
    Abstract [en]

    Most of the accidents at sea occurs in coastal or inner waterways, often with a dense traffic situation. This study investigates accidents in the Kiel canal caused by interaction. Even though the risks of hydrodynamic impact in traffic densed fairways are well known, accidents still occurs. The study consists of five reports, chosen from the german accident investigation board, which have been examined qualitatively with the analysis method HFACS-MA. By mapping the different underlying causes and with the help of a casual chain also identifying the cause categories behind each accident. Hopefully, by identifying and highlighting  the causes behind the accidents, this will prevent similar accidents to occur in the future. The study showed that the main causes behind these accidents were lack of communication or human interaction and insufficient surveillance of the traffic together with badly planned operations. The results showed some structurally deficiencies that authorities could improve upon. The study showed that knowledge and risk assessment for nautical officers and captains, pilots and vts-operators together with legislation or reviews of regulations on authority level, could reduce the risks of this type of accidents.

    Download full text (pdf)
    fulltext
  • 47.
    Dolguntseva, Irina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Eriksson, Sandra
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Electrical Approach to Output Power Optimization for a Point Absorbing Wave Energy Converter with a Direct Drive Linear Generator Power Take Off2017Conference paper (Refereed)
  • 48.
    Engsig-Karup, Allan P.
    et al.
    DTU Technical University of Denmark, Denmark.
    Eskilsson, Claes
    RISE - Research Institutes of Sweden, Safety and Transport, Safety. Aalborg University, Denmark.
    Spectral element FNPF simulations of focused wave groups impacting a fixed FPSO2018In: Proceedings of the Twenty-eighth (2018) International Ocean and Polar Engineering Conference, The International Society of Offshore and Polar Engineering , 2018, p. 1443-1450Conference paper (Refereed)
    Abstract [en]

    For  the assessment of experimental measurements of focused wave groups impacting a surface-piecing fixed structure, we present a new Fully Nonlinear Potential Flow (FNPF) model for simulation of unsteady water waves. The FNPF model is discretized in three  spatial dimensions (3D) using high-order prismatic - possibly curvilinear - elements using a  spectral  element  method (SEM) that has support for adaptive unstructured meshes. This  SEM-FNPF model is based on an Eulerian formulation and deviates from past works in that a  direct discretization of the Laplace problem is used making it straightforward to handle  accurately floating structural bodies of arbitrary shape. Our objectives are; i) present detail of a new SEM modelling developments and ii) to consider its application to address a wave-body interaction problem for nonlinear design waves and their interaction with a model-scale fixed Floating Production, Storage and Offloading vessel (FPSO).  We first reproduce  experimental measurements for focused design waves that represent a probably extreme  wave event for a sea state represented by a wave spectrum and seek to reproduce these measurements in a numerical wave tank. The validated input signal based on measurements is then generated in a NWT setup that includes the FPSO and differences in the signal caused by nonlinear diffraction is reported.

  • 49.
    Engsig-Karup, Allan P
    et al.
    DTU Technical University of Denmark, Denmark.
    Monteserin, Carlos
    DTU Technical University of Denmark, Denmark.
    Eskilsson, Claes
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety. RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability. Aalborg University, Denmark.
    A mixed Eulerian-Lagrangian spectral element method for nonlinear wave interaction with fixed structures2019In: Water Waves, ISSN 2523-367X, Vol. 1, p. 315-342Article in journal (Refereed)
    Abstract [en]

    We present a high-order nodal spectral element method for the two-dimensional simulationof nonlinearwaterwaves. The model is based on themixed Eulerian–Lagrangian(MEL) method. Wave interaction with fixed truncated structures is handled usingunstructured meshes consisting of high-order iso-parametric quadrilateral/triangularelements to represent the body surfaces as well as the free surface elevation. A numericaleigenvalue analysis highlights that using a thin top layer of quadrilateral elementscircumvents the general instability problem associated with the use of asymmetricmesh topology.We demonstrate howto obtain a robustMELscheme for highly nonlinearwavesusing an efficient combination of (i) global L2 projectionwithout quadratureerrors, (ii) mild modal filtering and (iii) a combination of local and global re-meshingtechniques. Numerical experiments for strongly nonlinear waves are presented. Theexperiments demonstrate that the spectral element model provides excellent accuracyin prediction of nonlinear and dispersive wave propagation. The model is also shownto accurately capture the interaction between solitary waves and fixed submerged andsurface-piercing bodies. The wave motion and the wave-induced loads compare wellto experimental and computational results from the literature.

  • 50.
    Engström, Jens
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Hydrodynamic Modelling for a Point Absorbing Wave Energy Converter2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Surface gravity waves in the world’s oceans contain a renewable source of free power on the order of terawatts that has to this date not been commercially utilized. The division of Electricity at Uppsala University is developing a technology to harvest this energy. The technology is a point absorber type wave energy converter based on a direct-driven linear generator placed on the sea bed connected via a line to a buoy on the surface.

    The work in this thesis is focused mainly on the energy transport of ocean waves and on increasing the transfer of energy from the waves to the generator and load. Potential linear wave theory is used to describe the ocean waves and to derive the hydrodynamic forces that are exerted on the buoy. Expressions for the energy transport in polychromatic waves travelling over waters of finite depth are derived and extracted from measured time series of wave elevation collected at the Lysekil test site. The results are compared to existing solutions that uses the simpler deep water approximation. A Two-Body system wave energy converter model tuned to resonance in Swedish west coast sea states is developed based on the Lysekil project concept. The first indicative results are derived by using a linear resistive load. The concept is further extended by a coupled hydrodynamic and electromagnetic model with two more realistic non-linear load conditions.

    Results show that the use of the deep water approximation gives a too low energy transport in the time averaged as well as in the total instantaneous energy transport. Around the resonance frequency, a Two-Body System gives a power capture ratio of up to 80 percent. For more energetic sea states the power capture ratio decreases rapidly, indicating a smoother power output. The currents in the generator when using the Two-Body system is shown to be more evenly distributed compared to the conventional system, indicating a better utilization of the electrical equipment. Although the resonant nature of the system makes it sensitive to the shape of the wave spectrum, results indicate a threefold increase in annual power production compared to the conventional system.

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