Relevant bibliographies by topics / Underwater Tethered Systems (UTS)

Academic literature on the topic 'Underwater Tethered Systems (UTS)'

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Published: 30 May 2022
Last updated: 31 May 2022

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Journal articles on the topic "Underwater Tethered Systems (UTS)"

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Блінцов, Олександр Володимирович. "Current problems of tethered underwater systems design." Technology audit and production reserves 5, no. 5(13) (September 11, 2013): 38–40. http://dx.doi.org/10.15587/2312-8372.2013.18406.

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Blintsov, V. S., O. P. Klochkov, and P. S. Kucenko. "CLASSIFICATION CHARACTERISTICS OF UNMANNED TETHERED UNDERWATER SYSTEMS AS A COMPONENT OF IMPROVING THE EFFICIENCY OF THEIR DESIGN." Scientific Bulletin Kherson State Maritime Academy 1, no. 22 (2020): 86–98. http://dx.doi.org/10.33815/2313-4763.2020.1.22.086-098.

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The design stage is considered to be rather resource-intensive in the entire process of creating marine robotic technology. Therefore, the applied scientific task of reducing the resource costs for those processes is of high interest. Among other things, the time consumed for design stage has to be reduced by determining the design characteristics at an early stage of design. The approach considered to reduce such costs involves structuring the classification features of tethered underwater systems in such a way as to simplify the selection and justification of design solutions at the stage of preliminary system design. For design engineers of underwater equipment, the list of classification features of tethered self-propelled and those towed underwater systems has been suggested. The list is based on a system approach and is structured according to material, energy, information and operational (functional) criteria. All of that enables performing the comparative assessment of existing systems upon key indicators and formalizing the processes of their synthesis at early stages of design. To demonstrate the capabilities of the system approach, the generalized algorithm for the organization of design works using the system of classification features of tethered self-propelled and towed underwater systems at the early stages of their design. The algorithm involves the formation and structuring of many classification features of such systems as the initial stage of the process of making effective design decisions in the early stages of design of underwater robotics. It has been revealed that putting in use the classification features system in question, enables deploying minimal project resources to make reference to the relevant databases and decide on already-existing artifact projects and select out of those available in the underwater equipment market key components and parts of underwater systems which would satisfy the requirements of the technical task of implementing the tethered underwater systems. That would significantly reduce the prime cost of design works and enhance the competitiveness of domestic science-based achievements in the markets of marine robotics.
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Блінцов, Олександр Володимирович. "The design conception of multipurpose underwater tethered systems with centralized data exchange." Eastern-European Journal of Enterprise Technologies 6, no. 9(66) (December 12, 2013): 31. http://dx.doi.org/10.15587/1729-4061.2013.19158.

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Olinger, David J. "Underwater Power Kites." Mechanical Engineering 139, no. 06 (June 1, 2017): 38–43. http://dx.doi.org/10.1115/1.2017-jun-2.

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This article discusses different features of underwater kites and its advantages in the turbine industry. The underwater kite moves fastest when it slaloms through the current in this way, much like a water skier. Electricity generated by the mounted turbine generator is transmitted along the tether to a moored, floating buoy, and then onto the power grid. This concept, now known as the Tethered Undersea Kite (TUSK), was first conceived by Magnus Landberg, a researcher in Sweden, in 2007. Underwater kites look to be feasible to build using commercial available technology. According to economic analyses conducted by other research teams, TUSK systems may be able to produce electricity at about half the current cost for fixed hydrokinetic turbines, and a bit below the cost of the power produced by offshore wind turbines. Those researchers attribute the lower costs to improved power-to-weight ratios derived from replacing the inner blades and support tower of a traditional turbine with a lightweight, low-cost tether.
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Klochkov, Oleksandr P. "The project tasks of single link self-propelled tethered underwater systems energy supply." Shipbuilding & marine infrastructure 1(11) (2019): 96–104. http://dx.doi.org/10.15589/smi2019.1(11).11.

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Alvarez, Miguel, and Hosam K. Fathy. "Outcomes and Insights From Simplified Analytic Trajectory Optimization for a Tethered Underwater Kite." IEEE Control Systems Letters 6 (2022): 2204–9. http://dx.doi.org/10.1109/lcsys.2021.3139589.

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Barker, Laughlin D. L., Michael V. Jakuba, Andrew D. Bowen, Christopher R. German, Ted Maksym, Larry Mayer, Antje Boetius, Pierre Dutrieux, and Louis L. Whitcomb. "Scientific Challenges and Present Capabilities in Underwater Robotic Vehicle Design and Navigation for Oceanographic Exploration Under-Ice." Remote Sensing 12, no. 16 (August 11, 2020): 2588. http://dx.doi.org/10.3390/rs12162588.

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This paper reviews the scientific motivation and challenges, development, and use of underwater robotic vehicles designed for use in ice-covered waters, with special attention paid to the navigation systems employed for under-ice deployments. Scientific needs for routine access under fixed and moving ice by underwater robotic vehicles are reviewed in the contexts of geology and geophysics, biology, sea ice and climate, ice shelves, and seafloor mapping. The challenges of under-ice vehicle design and navigation are summarized. The paper reviews all known under-ice robotic vehicles and their associated navigation systems, categorizing them by vehicle type (tethered, untethered, hybrid, and glider) and by the type of ice they were designed for (fixed glacial or sea ice and moving sea ice).
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Nedelcu, Andra-Teodora, Cătălin Faităr, Nicolae Buzbuchi, and Liviu Stan. "Study Simulation of Umbilical Cable for Underwater Vehicle." Bulletin of the Polytechnic Institute of Iași. Machine constructions Section 67, no. 3 (September 1, 2021): 19–32. http://dx.doi.org/10.2478/bipcm-2021-0014.

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Abstract This paper presents a series of analyses regarding the tethered umbilical cable in uniform current cable from the composition of the underwater remotely operated vehicle (ROV). The remotely operated vehicle is used in different undersea operation when it is important to control and determine precisely the disturbance forces generated by drag due to currents that act either on the vehicle directly or indirectly on the tether umbilical cable. The dynamics of umbilical cable represent an important part in ocean environment being used for signal and power transmission application. To perform the simulation in Ansys Aqwa, two axis systems are considered. A coordinate system related to the earth, represented by the key in front of which the measurements are made and a second coordinate system related to the vehicle at a set depth relative to the surface of the key. The results obtained from the simulation show us the drag forces that are exerted on the chosen cable for a given length, drag that appear both the seaborne platforms and underwater remotely vehicle contact.
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Sedunov, Alexander, Hady Salloum, Nikolay Sedunov, Christopher Francis, Sergey Tsyuryupa, Aleksandr Merzhevskiy, Daniel Kadyrov, and Alexander Sutin. "Stevens Passive Acoustic Detection System (SPADES -2) and its prospective application for windfarm underwater noise assessment." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A239. http://dx.doi.org/10.1121/10.0011185.

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Stevens Institute of Technology has been conducting development and field tests of various underwater passive acoustic systems for several years. Several such systems provided localization of boats and divers triangulation. The new version of SPADES has a tethered low-cost bottom-mounted circular 2.2-m underwater acoustic array with eight custom-built hydrophones. The cost of the array was significantly reduced by manufacturing the hydrophones in-house and utilizing a lightweight and low-cost tether. The tether can provide power and communication up to 1 km away and power to the data acquisition. The software has been developed for real-time direction-finding using Steered Power Response Phase Transform (SRP-PHAT) method, combined with region-zeroing (RZ) approach to multi-source separation and custom noise background estimation subtraction. The array was tested for seven months in the shallow and busy waters of the Hudson River tracking small boat activity. The system’s reliability and long tether make it attractive for long-term observation of underwater noise such as monitoring wind farm noise marine mammals and shipping traffic. Direction-finding can help identify noise unrelated to wind farms.
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Wernli, Robert. "The Present and Future Capabilities of Deep ROVs." Marine Technology Society Journal 33, no. 4 (January 1, 1999): 26–40. http://dx.doi.org/10.4031/mtsj.33.4.4.

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The following paper will present an overview of Remotely Operated Vehicles (ROVs) and, in particular, their use in the deep ocean, which includes depths beyond 10,000 feet. Although the intent of the paper is to address tethered, free-flying vehicles, the categories of deep towed vehicles and autonomous underwater vehicles (AUVs) will also be included for completeness. And, to properly discuss the state-of-the-art in such deep ocean systems, their capabilities in the depths less than 10,000 ft will also be addressed. An attempt to project their uses in the early stages of the next millennium wiU also be made.
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Dissertations / Theses on the topic "Underwater Tethered Systems (UTS)"

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Ghasemi, Amirmahdi. "Computational Modeling of Tethered Undersea Kites for Power Generation." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/56.

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Ocean currents and tidal energy are significant renewable energy resources, and new concepts to extract this untapped energy have been studied in the last decades. Tethered undersea kite (TUSK) systems are an emerging technology which can extract ocean current energy. TUSK systems consist of a rigid-winged kite, or glider, moving in an ocean current. One proposed concept uses an extendable tether between the kite and a generator spool on a fixed or floating platform. As the kite moves across the current at high speeds, hydrodynamic forces on the kite tension the tether which extends to turn the generator spool. Since the TUSK system is a new technology, the process of bringing a TUSK design to commercial deployment is long and costly, and requires understanding of the underlying flow physics. The use of computational simulation has proven to be successful in reducing development costs for other technologies. Currently, almost all computational tools for analysis of TUSK systems are based on linearized hydrodynamic equations in place of the full Navier-Stokes equations. In this dissertation, the development of a novel computational tool for simulation of TUSK systems is described. The numerical tool models the flow field in a moving three-dimensional domain near the rigid undersea kite wing. A two-step projection method along with Open Multi-Processing (OpenMP) on a regular structured grid is employed to solve the flow equations. In order to track the rigid kite, which is a rectangular planform wing with a NACA-0012 airfoil, an immersed boundary method is used. A slip boundary condition is imposed at the kite interface to decrease the computational run- time while accurately estimating the kite lift and drag forces. A PID control method is also used to adjust the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases to obtain desired kite trajectories. A baseline simulation study of a full-scale TUSK wing is conducted. The simulation captures the expected cross-current, figure-8 motions during a kite reel-out phase where the tether length increases and power is generated. During the following reel-in phase the kite motion is along the tether, and kite hydrodynamic forces are reduced so that net positive power is produced. Kite trajectories, hydrodynamic forces, vorticity contours near the kite, kite tether tension and output power are determined and analyzed. The performance and accuracy of the simulations are assessed through comparison to theoretical estimations for kite power systems. The effect of varying the tether (and kite) velocity during the retraction phase is studied. The optimum condition for the tether velocity is observed during reel-in phase to increase the net power of a cycle. The results match theoretical predictions for tethered wind energy systems. Moreover, the effect of the tether drag on the kite motion and resulting power output is investigated and compared with the results of the baseline simulation. The kite drag coefficient increases by 25% while the effect of the tether drag is included into the baseline simulation. It affects the trajectory and the velocity of the kite. However, it has a small effect on the power generation for the proposed concept of TUSK system.
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Трунін, К. С., and Kostiantyn S. Trunin. "Математична модель динаміки гнучкого зв’язку морської прив’язної системи з урахуванням впливу кручення гнучкого зв’язку на його силу розтягування." Thesis, 2021. http://eir.nuos.edu.ua/xmlui/handle/123456789/5035.

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Трунін, К. С. Математична модель динаміки гнучкого зв’язку морської прив’язної системи з урахуванням впливу кручення гнучкого зв’язку на його силу розтягування = The mathematical model of flexible link marine tethered system dynamic’s with account of torsion to it tensile force / К. С. Трунін // Матеріали XII міжнар. наук.-техн. конф. "Інновації в суднобудуванні та океанотехніці". – Миколаїв : НУК, 2021. – С. 115–119.
Важливою характеристикою гнучкого зв’язку (ГЗ) є опір крученню, яке виникає від процесу набігання на блок і вигину на блоці, і яке необхідно враховувати в умовах експлуатації. Запропоновано метод визначення векторів узагальнених сил кручення ГЗ. Досліджено вплив від кручення ГЗ на його силу розтягування на конкретних прикладах, у ряді випадків кручення ГЗ помітним чином впливає на характер руху ППС в цілому. Тема розробки ММ динаміки МПС з урахуванням впливу кручення є важливою і актульною.
The important of characteristic of flexible link (FL) is rigidity in bending (RB) which is probability be taken into account at regular service conditions. The elements of rope (wire) by endues testing also tension and bend with torsion. The method of calculation of vectors of generalized of forces of bend of FL was proposed. One of the causes of torsional stresses in the power plant of the Underwater Tethered Systems (UTS) is the interaction with ship equipment, in which the spiral winding on the winch drum, friction on the flanges of the pulleys or winch drums, bends on various blocks and rolls cause torsion. The source of torsional stresses in FL there may by technological reasons related to both the manufacture and storage, transportation and placement on the drooms ship’s winch.
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Conference papers on the topic "Underwater Tethered Systems (UTS)"

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Soylu, S., B. J. Buckham, and R. P. Podhorodeski. "Dynamics and control of tethered underwater-manipulator systems." In 2010 OCEANS MTS/IEEE SEATTLE. IEEE, 2010. http://dx.doi.org/10.1109/oceans.2010.5664366.

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Ghasemi, Amirmahdi, David J. Olinger, and Gretar Tryggvason. "Computational Investigation of Full-Scale Tethered Underwater Kite." In ASME 2018 Power Conference collocated with the ASME 2018 12th International Conference on Energy Sustainability and the ASME 2018 Nuclear Forum. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/power2018-7397.

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In this paper, a numerical simulation of three-dimensional motion of tether undersea kites (TUSK) for power generation is studied. TUSK systems includes a rigid-winged kite, or glider, moving in an ocean current in which a tethered kite is connected by a flexible tether to a fixed structure. Kite hydrodynamic forces are transmitted through the tether to an electrical generator on the fixed structure. The numerical simulation models the flow field in a three-dimensional domain near the rigid undersea kite wing by solving the full Navier-Stokes equations. In order to resolve the boundary layer near the kite surface, adequate grid resolution is needed which increases the computational run time drastically especially in 3D simulations. Therefore, in this study a slip boundary condition is implemented at the kite interface to accurately predict the total drag, with lower grid resolution. In order to reduce the numerical run times, a moving computational domain method is also used. A PID controller is used to adjuste the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases. A baseline simulation study of a full-scale TUSK system is conducted in which the expected cross-current, figure-8 motions during a kite reel-out phase is captured. The effect of the tether drag on the kite motion and resulting power output is also investigated and compared with the results of the baseline simulation.
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Aldana, Andrés F., Helio Sneyder Esteban Villegas, and Sebastián Roa Prada. "Iterative Modeling of a Small Underwater Tethered Remotely Operated Vehicle." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-88501.

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Remotely operated vehicles, ROV, are highly versatile robotic systems, which are currently the best alternative to carry out deep-sea tasks, that otherwise could compromise the safety of human lives. These vehicles are commonly used by several industries such as offshore oil companies, offshore wind energy companies and environmental organizations. These underwater vehicles may be classified as Free-Swimming Systems, FSS, or Tether Management Systems, TMS. Tether Management Systems use the cable to transmit data and steering commands, and as a mean for power supply. It is known that the cable has a strong influence on the dynamics and maneuverability of a ROV. To improve the motion accuracy and stability of the control of a ROV, it is necessary to understand the nature and to estimate the value of the mutual reaction forces between the ROV and the cable. This research seeks the modeling of the overall underwater tethered vehicle, by iteratively coupling the results from the finite element analysis, FEA, of the cable with the dynamic model of the ROV, as obtained by using the standard Newton-Euler formulation. Morison equation is employed to obtain the cable transient response. In this work, the ROV tether is defined as a flexible, slender cylinder, with circular cross section and made of a material with nonlinear elastic behavior. The cable is assumed to be in a specific extended initial configuration, with one of its ends fixed in ground. The FEA analysis of the cable is performed with the help of the commercial software COMSOL Multiphysics. A commercial small ROV is selected as the case study to apply the Newton-Euler method, considering the location of its actuators and other actual parameters such as mass, matrix of mass moments of inertia and drag coefficients. To include the cable forces into the dynamic model of the ROV, it is necessary to perform an iterative process between the cable analysis results and the ROV open loop response. The modeling approach starts with an FSS system initial velocity, which is fed into the cable FEA analysis. Both analyses are iterated, following a mutual feedback scheme, until results converge, obtaining the complete tethered vehicle model. The main achievement of this investigation is to observe the cable influence on the ROV, providing results that prove to be extremely useful for future work on the control system design, taking into account the disturbances introduced by the cable.
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Ghasemi, Amirmahdi, David J. Olinger, and Gretar Tryggvason. "Simulation of Tethered Underwater Kites: Three Dimensional Trajectories for Power Generation." In ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59141.

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In this paper, a numerical simulation of three dimensional motion of tether undersea kites (TUSK) for power generation is studied. TUSK systems consist of a rigid-winged kite, or glider, moving in an ocean current. One proposed concept uses a tethered kite which is connected by a flexible tether to a support structure with a generator on the ocean surface. The numerical simulation models the flow field in a three-dimensional domain near the rigid undersea kite wing by solving the full Navier-Stokes equations. A two-step projection method along with Open Multi-Processing (OpenMP) is employed to solve the flow equations. In order to track the rigid kite, an immersed boundary method is used. A NACA 0021 airfoil is used for the cross section shape of the kite, and the tension forces in the elastic tethers are modeled by a simple Hooke’s law. A grid refinement study has been carried out to ensure the independence of the numerical results on the grid mesh resolution. Also, the Reynolds number independency has been studied. PID control methods are used to adjust the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases to obtain desired kite trajectories. During the reel-out phase the kite moves in successive cross-current motions in a figure-8 pattern, the tether length increases and power is generated. During reel-in the kite motion is along the tether, and kite hydrodynamic forces are reduced so that net positive power is produced. Kite trajectories, hydrodynamic forces on the kite, kite tether tension and output power are determined and analyzed for a baseline TUSK simulation.
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Ghasemi, Amirmahdi, David J. Olinger, and Gretar Tryggvason. "Simulation of Tethered Underwater Kites Moving in Three Dimensions for Power Generation." In ASME 2017 11th International Conference on Energy Sustainability collocated with the ASME 2017 Power Conference Joint With ICOPE-17, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/es2017-3425.

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In this paper, a numerical simulation of tether undersea kites (TUSK) used for power generation is undertaken. The effect of varying key design parameters in these systems is studied. TUSK systems consist of a rigid-winged kite, or glider, moving in an ocean current. One proposed TUSK concept uses a tethered kite which is connected by a flexible tether to a support structure with a generator on a surface buoy. The numerical simulation models the flow field in a three-dimensional domain near the rigid undersea kite wing by solving the full Navier-Stokes equations. A moving computational domain method is used to reduce the computational run times. A second-order corrector-predictor method, along with Open Multi-Processing (OpenMP), is employed to solve the flow equations. In order to track the rigid kite, which is a rectangular planform wing with a NACA 0021 airfoil, an immersed boundary method is used. The tension force in the elastic tether is modeled by a simple Hooke’s law, and the effect of tether damping is added. PID control methods are used to adjust the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases to obtain the desired kite trajectories. During the reel-out phase the kite moves in successive cross-current motions in a figure-8 pattern, the tether length increases and power is generated. During reel-in the kite motion is along the tether, and kite hydrodynamic forces are reduced so that net positive power is produced. The effects of different key design parameters in TUSK systems, such as the ratio of tether to current velocity, and tether retraction velocity, are then further studied. System power output, kite trajectories, and vorticity flow fields for the kite are also determined.
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Wang, Yao, and David J. Olinger. "Modeling and Simulation of Tethered Undersea Kites." In ASME 2016 10th International Conference on Energy Sustainability collocated with the ASME 2016 Power Conference and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/es2016-59123.

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In this work an emerging hydrokinetic energy technology, Tethered UnderSea Kites (TUSK), is studied. TUSK systems use an axial-flow turbine and generator mounted on a rigid, underwater winged kite that is tethered to a floating surface buoy to extract power from an ocean current. The tethered underwater kite is controlled to travel in cross-current motions at a high velocity which is at least four to five times larger than the ocean current velocity. This higher velocity significantly increases the potential power output compared to conventional fixed marine turbines. Modeling and simulation of the kite-tether dynamics in a TUSK system is studied by developing and solving governing equations of motion derived from Euler-Lagrange equations. Models for physical effects appropriate to TUSK systems are developed, including for turbine power and turbine drag, kite wing hydrodynamic forces, and the effect of turbine blade tip cavitation on turbine power output. A baseline simulation that includes these modeled effects and a simple kite control scheme is studied to estimate cross-current kite trajectories, turbine power output, kite hydrodynamic forces, kite pitch, roll and yaw dynamics, and tether tensions. Once the baseline simulation case has been fully explored, a parametric study is conducted that varies key design and flow parameters including ocean current speed, kite weight and wing area, turbine rotor area, tether length, and kite control system parameters.
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Carretero, J. A., and B. J. Buckham. "Simulation of Submerged Slack Tethers and Their Interaction With the Environment." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51311.

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Tethered systems, underwater or otherwise, are nowadays used for very diverse tasks. Due to the complexity of such systems, it is necessary to simulate them for design, operation and training purposes. This paper deals with an approach to simulation of tethered systems, in particular underwater remotely operated vehicles (ROVs), by incorporating contact forces acting between the tether and the environment into the dynamic model of the tether. This will ensure model fidelity when the tethered system is operated in a dense environment. In this paper, methods used to compute contact forces are described. In the calculation of contact dynamics, the distance between the tethered system and the environment is of utmost interest. Algorithms to determine the separation distance between the tether and the environment are discussed in the scope of this work. These algorithms are then incorporated into an existing dynamics model of the ROV tether. Finally, this paper concludes with a simple numerical example where a tether is moved in a concave environment. The distance between the tether and the environment is computed as the tether’s location and three-dimensional profile change with time.
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Shahab, Shima, and Alper Erturk. "Underwater Dynamic Actuation of Macro-Fiber Composite Flaps With Different Aspect Ratios: Electrohydroelastic Modeling, Testing, and Characterization." In ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7538.

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Macro-fiber composite (MFC) actuators offer simple and scalable design, robustness, noiseless performance, strong electromechanical coupling, and particularly a balance between the actuation force and deformation capabilities, which is essential to effective and agile biomimetic locomotion. Recent efforts in our lab have shown that MFC bimorphs with polyester electrode sheets can successfully be employed for fish-like aquatic locomotion in both tethered and untethered operation. MFC swimmers can outperform other smart material-based counterparts, such as the compliant ionic polymer-metal composite based swimmers, in terms of swimming speed per body length. Cantilevered flaps made of MFC bimorphs with different aspect ratios can be employed for underwater actuation, sensing, and power generation, among other aquatic applications of direct and converse piezoelectric effects. In an effort to develop linearized electrohydroelastic models for such cantilevers, the present work investigates MFC bimorphs with three different aspect ratios. The MFCs used in this study use the 33-mode of piezoelectricity with interdigitated electrodes. Underwater dynamic actuation frequency response functions (FRFs) of the MFCs are defined as the tip velocity per actuation voltage (tip velocity FRF) and current consumption per actuation voltage (admittance FRF). The tip velocity and admittance FRFs are modeled analytically for in-air actuation and validated experimentally for all aspect ratios. Underwater tip velocity and admittance FRFs are then derived by combining their in-air counterparts with corrected hydrodynamic functions. The corrected hydrodynamic functions are also identified from aluminum cantilevers of similar aspect ratios. Both tip vibration and current consumption per voltage input are explored. The failure of Sader’s hydrodynamic function for low length-to-width aspect ratios is shown. Very good correlation is observed between model simulations and experimental measurements using aspect ratio-dependent, corrected hydrodynamic function.
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Golz, Matthias, Florin Boeck, Sebastian Ritz, and Gerd Holbach. "A Ballast System for Automated Deep-Sea Ascents." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54841.

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Abstract:
The efforts to discover the world’s oceans — even in extremely deep-sea environments — have grown more and more in the past years. In this context, unmanned underwater vehicles play a central role. Underwater systems that are not tethered need to provide an apparatus to ensure a safe return to the surface. Therefore, positive buoyancy is required and can be achieved by either losing weight or expanding volume. A conservative method is the dropping of ballast weight. However, nowadays this method is not appropriate due to the environmental impact. This paper presents a ballast system for an automated ascent of a deep-sea seabed station in up to 6000 m depth. The ballast system uses a DC motor driven modified hydraulic pump and a compressed air auxiliary system inside a pressure vessel. With regard to the environmental contamination in case of a leakage, only water is used as ballast fluid. The modification of an ordinary oil-hydraulic radial piston pump and the set-up of the ballast system is introduced. Results from sea trials in the Atlantic Ocean are presented to verify the functionality of the ballast system.
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