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Academic literature on the topic 'Flexible tethers'

Author: Grafiati

Published: 19 February 2023

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Journal articles on the topic "Flexible tethers"

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Hong, Aaron Aw Teik, and Renuganth Varatharajoo. "Tether Tension Performance Utilizing Various Materials for a Coplanar and Non-Coplanar Model of a Flexible Tethered Satellite System." Applied Mechanics and Materials 629 (October 2014): 281–85. http://dx.doi.org/10.4028/www.scientific.net/amm.629.281.

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This paper presents a numerical model for a flexible tethered satellite system in both planar and co-planar environment. This tethered satellite system consists of three rigid bodies with two flexible tethers, each connecting two rigid bodies with one located in the center serving as the mothership. The dynamics of the system include tether deformations, rotational dynamics and orbital mechanics. Five different materials that are commonly used will be tested accordingly in order to observe its performance based on the tension of the tether. It is found that, based on all of the materials simulated, diamond has the best tension performance.

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CHAN, ELAINE R., LIN C. HO, and SHARON C. GLOTZER. "MESOSCALE COMPUTER SIMULATIONS OF POLYMER-TETHERED ORGANIC/INORGANIC NANOCUBE SELF-ASSEMBLY." International Journal of Modern Physics C 20, no. 09 (September 2009): 1443–56. http://dx.doi.org/10.1142/s0129183109014503.

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A molecular simulation study of the mesoscale self-assembly of tethered nanoparticles having a cubic geometry is presented. Minimal models of the tethered nanocubes are developed to represent a polyhedral oligomeric silsesquioxane (POSS) molecule with polymeric substituents. The models incorporate some of the essential structural features and interaction specificity of POSS molecules, and facilitate access to the long length and timescales pertinent to the assembly process while foregoing atomistic detail. The types of self-assembled nanostructures formed by the tethered nanocubes in solution are explored via Brownian dynamics simulations using these minimal models. The influence of various parameters, including the conditions of the surrounding medium, the molecular weight and chemical composition of the tether functionalities, and the number of tethers on the nanocube, on the formation of specific structures is demonstrated. The role of cubic nanoparticle geometry on self-assembly is also assessed by comparing the types of structures formed by tethered nanocubes and by their flexible coil triblock copolymer and tethered nanosphere counterparts. Morphological phase diagrams are proposed to describe the behavior of the tethered nanocubes.

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Puig-Suari, Jordi. "Optimal Mass Flexible Tethers for Aerobraking Maneuvers." Journal of Guidance, Control, and Dynamics 20, no. 5 (September 1997): 1018–24. http://dx.doi.org/10.2514/2.4149.

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Paley, Dror, and Claire Shannon. "Rotational Guided Growth: A Preliminary Study of Its Use in Children." Children 10, no. 1 (December 29, 2022): 70. http://dx.doi.org/10.3390/children10010070.

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Torsional malalignment of the legs is common in children, and those that do not remodel may benefit from surgical correction. Traditionally, this is corrected with an open osteotomy. Guided growth is the gold standard for minimally invasive angular correction and has been investigated for use in torsional deformities. This study presents our preliminary results of rotationally guided growth in the femur and tibia using a novel technique of peripheral flexible tethers. A total of 8 bones in 5 patients were treated with flexible tethers consisting of separated halves of a hinge plate (Orthopediatrics Pega Medical, Montreal, QC, Canada), which were fixed to the epiphysis and metaphysis at 45° angles to the physis and connected with Fibertape (Arthrex, Naples, FL, USA). The implants are placed medially and laterally in the opposite 45° inclination, determined by the desired direction of rotation. Additionally, the average treatment time was 12 months. All patients corrected the rotational malalignment by clinical evaluation. The average rotational change was 30° in the femurs and 9.5° in the tibias. Further, the average follow-up was 18 months, with no recurrence of the rotational deformity. There was no change in longitudinal growth in the patients who underwent bilateral treatment. Rotational guided growth with flexible tether devices is a novel technique that successfully corrects torsional malalignment without invasive osteotomy surgery.

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Williams, Paul. "Electrodynamic Tethers Under Forced-Current Variations Part II: Flexible-Tether Estimation and Control." Journal of Spacecraft and Rockets 47, no. 2 (March 2010): 320–33. http://dx.doi.org/10.2514/1.45733.

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Singh, Devendra, and Jubaraj B. Baruah. "Guest inclusion in cyclic imides containing flexible tethers." Journal of Inclusion Phenomena and Macrocyclic Chemistry 76, no. 3-4 (June 23, 2012): 269–81. http://dx.doi.org/10.1007/s10847-012-0196-7.

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Zhong, Yini, and Rui Zhong. "Dynamics, Deployment and Retrieval Strategy for Satellite-Sail Transverse Formation with Model Inaccuracy." Aerospace 9, no. 10 (October 14, 2022): 602. http://dx.doi.org/10.3390/aerospace9100602.

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One of the important applications of the space tethered system is formation flying. To satisfy the requirement for interferometry of ground targets by remote-sensing satellites, a new type of tethered solar sail spacecraft has been proposed in recent research. The replacement of subsatellites of conventional tethered satellite systems with solar sail spacecraft allows for a special formation configuration in which the main satellite is in sun-synchronous orbit and the subsolar sail is in displaced orbit. If the solar sail is at the appropriate attitude, the main satellite and the solar sail spacecraft connected by metal tethers could move side by side, hence this formation system is called transverse formation. The relative baseline of this transverse formation system is perpendicular to the ground trajectory of the satellite, effectively solving the problem that the relative baseline of conventional orbital formations varies in a trigonometric cycle. Researchers on the past ignored the mass and elasticity of the tether, and considered the tether just a constraint in the model system. Since the solar sail is generally quite light compared to the other components of the system, the model inaccuracy caused by ignoring the mass of the tether on the dynamic model and control is extremely obvious. This paper investigates the relative dynamics and control of a proposed system during the deployment process with the mass of the tether. Two precise models of satellite-sail systems are established. One is based on the dumbbell model with the mass tether for the tethered satellite system, and the other is on the basis of the beads model of a tethered satellite system. The rigid one is for control design and the flexible one is for dynamic simulation. It is concluded that the length of the tether and attitude angle of the transverse formation configuration can be decoupled and controlled separately. On the basis of the models, a length rate and LQR control law is developed and the control of the deployment and retrieval process of the tethered solar sail system is investigated. Numerical simulations are performed to verify the accuracy of the conclusions.

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Klán, Petr, and Peter J. Wagner. "Intramolecular Triplet Energy Transfer in Bichromophores with Long Flexible Tethers." Journal of the American Chemical Society 120, no. 9 (March 1998): 2198–99. http://dx.doi.org/10.1021/ja974016+.

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Lucas, Jeffrey M., Joelle A. Labastide, Lang Wei, Jonathan S. Tinkham, Michael D. Barnes, and Paul M. Lahti. "Carpenter’s Rule Folding in Rigid–Flexible Block Copolymers with Conjugation-Interrupting, Flexible Tethers Between Oligophenylenevinylenes." Journal of Physical Chemistry A 119, no. 29 (June 30, 2015): 8010–20. http://dx.doi.org/10.1021/acs.jpca.5b02295.

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Mankala, Kalyan K., and Sunil K. Agrawal. "Equilibrium-to-Equilibrium Maneuvers of Flexible Electrodynamic Tethers in Equatorial Orbits." Journal of Spacecraft and Rockets 43, no. 3 (May 2006): 651–58. http://dx.doi.org/10.2514/1.13956.

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Dissertations / Theses on the topic "Flexible tethers"

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Tyc, George. "Dynamics and stability of spinning flexible space tether systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0008/NQ32028.pdf.

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Ismail, Norilmi Amilia. "The dynamics of a flexible Motorised Momentum Exchange Tether (MMET)." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3115/.

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This research presents a more complete flexible model for the Motorised Momentum Exchange Tether (MMET) concept. In order to analyse the vibration aspect of the problem the tether is modelled as a string governed by partial differential equations of motion, with specific static and dynamic boundary conditions and the tether sub-span is flexible and elastic, thereby allowing three dimensional displacements of the motorised tether. The boundary conditions lead to a specific frequency equation and the Eigenvalues from this provide the natural frequencies of the orbiting flexible motorised tether when static, accelerating in spin, and at terminal angular velocity. The rotation matrix is utilized to get the position vectors of the system’s components in an inertial frame. The spatio-temporal coordinates u(x,t), v(x,t) and w(x,t) are transformed to modal coordinates before applying Lagrange’s equations and the pre-selected linear modes are included in generating the equations of motion. The equations of motion contain inertial nonlinearities of cubic order, and these show the potential for intricate intermodal coupling effects. The study of planar and non-planar motions has been carried out and the differences in the modal responses in both motions between the rigid body and flexible model are highlighted and discussed. The dynamics and stability of the flexible MMET is investigated using the dynamical analysis tools for representing the behaviour of the tether system. The study is also includes the engineering side of the MMET by investigating the power requirements of an electric motor located in the central facility of the Motorised Momentum Exchange Tether (MMET). A simulation was run using a specially written computer program to obtain the required minimum power for a typical duty cycle, and also to study the responses for three different operating conditions; before payload release, torque-off and reverse torques conditions for both the propulsion and outrigger system on both circular and elliptical orbits. The differences in the responses when using rigid body and flexible models of MMET are highlighted and discussed in order to look at the sensitivity of the model to the power budget calculations. The study then continues with a comparative study between the MMET and conventional propulsion systems in terms of the energy used specifically for an Earth-Moon return mission for circular and elliptical orbits.

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Pidgeon, Robert W. "Dynamics and control of a flexible tethered system with offset." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30273.

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A mathematical model of a platform based flexible tethered satellite system in an arbitrary orbit, undergoing planar motion, is obtained using the Lagrangian procedure. The governing equations of motion account for the platform and tether pitch, longtitu-dinal tether oscillations, offset of the tether attachment point as well as deployment and retrieval of the tether. A numerical parametric study of the highly nonlinear, nonautonomous and coupled equations of motion gives considerable insight into the system dynamics useful in its design. Of particular interest are the interactions involving orbital eccentricity, system librations, tether flexibility and offset, retrieval maneuvers and initial disturbances. Results show that the offset strongly couples tether and platform dynamics, and the resulting responses show high frequency modulations corresponding to the longtitudinal tether oscillations. The system was found to be unstable during retrieval. The Linear Quadratic Regulator based offset control strategy, in conjunction with the platform mounted momentum gyros, is proposed to alleviate the situation. Results show that a strategy involving independent parallel control of low and high frequency responses can damp rather severe disturbances in a fraction of an orbit.
Science, Faculty of
Mathematics, Department of
Graduate

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Chen, Yi. "Dynamical modelling of a flexible motorised momentum exchange tether and hybrid fuzzy sliding mode control for spin-up." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1844/.

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A space tether is a long cable used to couple satellites, probes or spacecrafts to each other or to other masses, such as a spent booster rocket, space station, or an asteroid. Space tethers are usually made of thin strands of high-strength fibres or conducting wires, which range from a few hundred metres to several kilometres and have a relatively small diameter. Space tethers can provide a mechanical connection between two space objects that enables a transfer of energy and momentum from one object to the other, and as a result they can be used to provide space propulsion without consuming propellant. Additionally, conductive space tethers can interact with the Earth's magnetic field and ionospheric plasma to generate thrust or drag forces without expending propellant. The motorised momentum exchange tether (MMET) was first proposed by Cartmell in 1996 and published in 1998. The system comprises a specially designed tether connecting two payload modules, with a central launcher motor. For the purposes of fundamental dynamical modelling the launcher mass can be regarded as a two part assembly, where the rotor is attached to one end of each tether subspan, and the other side is the stator, which is attached to the rotor by means of suitable bearings. Both the launcher and the payload can be attached to the tether by means of suitable clamps or bearing assemblies, dependent on the requirements of the design. The further chapters in this thesis focus on a series of dynamical models of the symmetrical MMET syste, including the dumbbell MMET system, the solid massless MMET system, the flexible massless MMET system, the solid MMET system and the discretised flexible MMET system. The models in this context have shown that including axial, torsional and pendular elasticity, the MMET systems have a significant bearing on overall performance and that this effect should not be ignored in future, particularly for control studies. All subsequent analyses for control applications should henceforth include flexible compliance within the modelling procedure. Numerical simulations have been given for all types of MMET models, in which, accurate and stable periodic behaviours are observed, including the rigid body motions, the tether spin-up and the flexible motions, with proper parameter settings. The MMET system's spin-up control methods design and analysis will henceforth be referenced on the results. For the non-linear dynamics and complex control problem, it was decided to investigate fuzzy logic based controllers to maintain the desired length and length deployment rate of the tether. A standard two input and one output fuzzy logic control (FLC) is investigated with numerical simulations, in which the control effects on the MMET system's spin-up are observed. Furthermore, to make the necessary enhancement to the fuzzy sliding mode control, a specialised hybrid control law, named F$\alpha$SMC is proposed, which combines fuzzy logic control with a SkyhookSMC control law together, then it is applied for the control of motorised space tether spin-up coupled with an flexible oscillation phenomenon. It is easy to switch the control effects between the SkyhookSMC and the FLC modes when a proper value of $\alpha$ is selected $(0<\alpha<1)$ to balance the weight of the fuzzy logic control to that of the SkyhookSMC control, and the hybrid fuzzy sliding mode controller is thus generated. Next, the simulations with the given initial conditions have been devised in a connecting programme between the control code written in $MATLAB$ and the dynamics simulation code constructed within $MATHEMATICA$. Both the FLC and the hybrid fuzzy sliding mode control methods are designed for the control of spin-up of the discretised flexible MMET system with tether-tube subspans, and the results have shown the validated effects of both these control methods for the MMET system spin-up with included flexible oscillation. To summarise, the objectives of this thesis are, firstly, to propose a series of new dynamical models for the motorised momentum exchange tethers; secondly, to discuss two types of control methods for the spin-up behaviour of a flexible motorised momentum exchange tether, which include a fuzzy logic control and a hybrid fuzzy sliding mode control. By the weight factor $\alpha$, fuzzy logic control and SkyhookSMC controllers can be balanced from one to each other, and there is observed difference for each of the elastic behaviour in the MMET system involving these MMET systems with different controllers - FLC($\alpha = 1$), F$\alpha$SMC($\alpha = 0.5$) and SkyhookSMC($\alpha = 0.0$). The results state the control effects for FLC, F$\alpha$SMC and FLC, which lead to stable spin-up behaviour with flexible oscillations.

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Newcomb, Lisa Frances. "Investigation of aromatic-aromatic interactions in water using aromatic groups joined by flexible tethers." 1995. http://catalog.hathitrust.org/api/volumes/oclc/33807846.html.

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(9874484), PJP Foley. "DNA bis-intercalators: Design, synthesis and DNA binding properties of potential anti-cancer agents based on rigid polynorbornyl molecular scaffolds." Thesis, 2001. https://figshare.com/articles/thesis/DNA_bis-intercalators_Design_synthesis_and_DNA_binding_properties_of_potential_anti-cancer_agents_based_on_rigid_polynorbornyl_molecular_scaffolds/13423973.

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DNA bis-intercalating agents constitute an important class of compounds for cancer chemotherapy. The work presented in this dissertation deals with the synthesis of a new class of DNA bis-intercalating agents of type I containing rigid polynorbomyl molecular frameworks. The highly rigid molecular framework is designed to place and orient the two intercalating chromophores (the DNA-reactive entities) optimally for specific binding to a known nucleotide sequence. The chromophores are attached to the rigid framework via short flexible tethers, allowing some degree of conformational mobility while maintaining well-defined maximum and minimum inter-chromophore separations. A modular approach to synthesis has been adopted to prepare the bis-intercalators that involved initial preparation of a series of complementary A-BLOCKs II and B-BLOCKIII (Scheme I), each of which contains one intercalating chromophore. These BLOCKs contain different end-functionality (A-BLOCK: alkene; B-BLOCK: epoxide) which react with each other stereospecifically, but not with themselves to produce the desired product IV. The wide range of topologically well defined products generated by this approach show variations which include spacer length, chromophore type and nature of the tether joining the chromophores to the rigid molecular framework. In particular, the BLOCK approach has permitted the preparation of the most comprehensive range of asymmetrical bis-intercalators containing rigid spacers yet described. Representative products derived from this methodology, include the bisacridine V and the acridine-naphthalimide mixed derivative VI. In addition, significant advances have been made to control the hydrophilicity of these drugs, thereby enhancing the bio-compatibility of these novel molecules. DNA binding experiments have been performed on the bis-intercalators prepared in this study. Polynucleotide structural selectivity was observed and sequence-selectivity was associated with the binding of two of the compounds with the highest affinity for DNA. Some features that enhance binding selectivity and affinity have been identified so that the synthesis of more selective compounds for effective gene targeting in chemotherapy can proceed in the future. The results which have helped to define more clearly the parameters of drug-DNA interaction represent a good example of how organic chemistry can be a useful tool to help elucidate and understand biological phenomena. The ground work has been completed providing a solid foundation from which the preparation of novel synthetic targets of medicinal interest using the BLOCK coupling concept can now be approached with less trepidation.

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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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Books on the topic "Flexible tethers"

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Frost, Geoffrey W. Two projectiles connected by a flexible tether dropped in the atmosphere. 1999.

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Book chapters on the topic "Flexible tethers"

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Banerjee, Arun K. "Deployment, Station-Keeping, and Retrieval of a Flexible Tether Connecting a Satellite to the Shuttle." In Flexible Multibody Dynamics, 51–92. 2nd ed. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003231523-3.

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Brochard-Wyart, F., and A. Buguin. "Tethered Polymer Chains under Strong Flows: Stems and Flowers." In Flexible Polymer Chains in Elongational Flow, 41–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-58252-3_3.

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Kudo, Kenko, and Yoshiaki Terumichi. "Numerical Analysis Method for Flexible Tether with Time-Varying Length Across a Variable Boundary." In Vibration Engineering for a Sustainable Future, 59–65. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-46466-0_9.

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Schmidt, C. F., K. Svoboda, N. Lei, C. R. Safinya, S. M. Block, and D. Branton. "The Isolated Human Red Blood Cell Skeleton: An Example of a Flexible Tethered Membrane." In Springer Proceedings in Physics, 128–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-84763-9_24.

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Fagiano, Lorenzo, Aldo U. Zgraggen, and Manfred Morari. "On Modeling, Filtering and Automatic Control of Flexible Tethered Wings for Airborne Wind Energy." In Airborne Wind Energy, 167–80. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-39965-7_9.

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Ishihsra, Daiki, Yoshiaki Terumichi, and Shoichiro Takehara. "A Study on Coupled Vibration Between Flexible Body and Rigid Body in Tethered System." In Vibration Engineering for a Sustainable Future, 219–25. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-46466-0_30.

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"Insights And Approximations In Dynamic Analysis Of Spacecraft Tethers." In Mechanics And Control Of Large Flexible Structures, 667–96. Washington DC: American Institute of Aeronautics and Astronautics, 1990. http://dx.doi.org/10.2514/5.9781600866029.0667.0696.

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"Deployment, Station-Keeping, and Retrieval of a Flexible Tether Connecting a Satellite to the Shuttle." In Flexible Multibody Dynamics, 29–61. Oxford, UK: John Wiley & Sons, Ltd, 2016. http://dx.doi.org/10.1002/9781119015635.ch2.

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"Dynamics And Control Of Tethered Spacecraft During Deployment And Retrieval." In Mechanics And Control Of Large Flexible Structures, 145–81. Washington DC: American Institute of Aeronautics and Astronautics, 1990. http://dx.doi.org/10.2514/5.9781600866029.0145.0181.

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Conference papers on the topic "Flexible tethers"

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Williams, Paul. "Optimal Control of Flexible Tethers." In 54th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2003. http://dx.doi.org/10.2514/6.iac-03-a.6.05.

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Valverde, J., J. L. Escalona, J. Domi´nguez, and E. Freire. "Stability and Dynamic Analysis of the SET (Short Electrodynamic Tether)." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48323.

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Space-tethers are very slender and flexible structures that are deployed in space. In recent times space-tethers have been the object of numerous studies in the field of astronautics. One of such structures is the SET (Short Electrodynamic Tether). The distinguishing characteristic of the SET is that it orbits with the axis of smallest moment of inertia normal to the orbit plane. The SET is in continuous rotation around this same axis, which allows it to maintain the aforementioned operating position. In most other cases, space-tethers orbit within the orbit plane. The SET is not perfectly straight after deployment. This fact could make the rotation unstable from the structural point of view, as predicted by the linear study of unbalanced rotors (supercritical velocities). However, if non-linear terms in the elastic and internal damping forces are considered in the model (hysteresis causes instability) the resulting motion of the structure could remain bounded. This assertion was shown in a previous study by the authors, through dynamic simulations of the system. In order to confirm these results, the present paper studies the stability of the SET’s solutions. A modified Jeffcott model will be the object of this study. The paper will end with a comparison of the results obtained with those rendered by previous works.

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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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Ram, Jeffrey L., and Yi Lu. "Bioinformatics Pipeline for Identification of Binding Motifs of Flexible Protein Tethers." In 2009 IEEE International Conference on Bioinformatics and Biomedicine (BIBM). IEEE, 2009. http://dx.doi.org/10.1109/bibm.2009.20.

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Williams, Paul, Chris Blanksby, Pavel Trivailo, and Hironori Fujii. "Libration Control of Flexible Tethers Using Electromagnetic Forces and Movable Attachment." In AIAA Guidance, Navigation, and Control Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2003. http://dx.doi.org/10.2514/6.2003-5781.

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Mankala, Kalyan, and Sunil Agrawal. "Equilibrium-to-Equilibrium Maneuvers of Flexible Electrodynamic Tethers in Equatorial Orbits." In AIAA Guidance, Navigation, and Control Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2004. http://dx.doi.org/10.2514/6.2004-5342.

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Nejad, Alireza Mahdavi, David J. Olinger, and Gretar Tryggvason. "Numerical Modeling of Kites for Power Generation." In ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21168.

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A computational model of a massless kite that produces power in an airborne wind energy system (AWE) is presented. AWE systems use tethered kites at high altitudes to extract energy from the wind, and are being considered as an alternative to wind turbines since the kites can move in high-speed cross-wind motions over large swept areas to increase power production. In our model the kite completes successive power-retraction cycles where the kite angle of attack is altered as required to vary the resultant aerodynamic forces on the kite. The numerical simulation models the flow field in a two-dimensional domain near the flexible kite by solving the full Navier-Stokes equations. Eulerian grid points for the flow domain together with a Lagrangian representation of the kite are employed. The flow field is determined through a second-order finite difference projection method using a non-uniform mesh on a staggered grid. A corrector-predictor technique is employed to ensure the second-order accuracy in time of the numerical simulation. The two-dimensional kite shape is modeled as a slightly cambered immersed boundary that evolves with the flow. The flexible kite surface is modeled with a set of linear springs following Hooke’s law. The unstretched length of each elastic tether at a given time step is controlled using periodic triangular wave shapes to achieve the required power-retraction phases. A study was conducted in which the wave shape amplitude, frequency, and phase (between two tethers) was adjusted to achieve a suitably high net power output with very good agreement to predictions for Loyd’s simple kite in two-dimensional motion. Aerodynamic coefficients for the kite, tether tensions, tether reel-out and reel-in speeds, and vorticity flowfields in the kite wake are also determined.

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Takehara, Shoichiro, Yoshiaki Terumichi, Masahiro Nohmi, Kiyoshi Sogabe, and Yoshihiro Suda. "Numerical and Experimental Approaches on the Motion of a Tethered System With Large Deformation, Rotation and Translation." In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84799.

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In this paper, we discuss the motion of a tethered system. In general, a tether is a cable or wire rope, and a tethered system consists of a tether and attached equipment. A tethered subsatellite in space is an example of this system. We consider the tethered system consisting of a very flexible body (the tether) and rigid bodies at one end as our analytical model. A flexible body in planer motion is described using the Absolute Nodal Coordinate Formulation. Using this method, the motion of a flexible body with large deformation, rotation and translation can be expressed with the accuracy of rigid body motion. The combination of flexible body motion and rigid body motion is performed and the interaction between them is discussed. We also performed experiments to investigate the fundamental motion of the tethered system and to evaluate the validity of the numerical formulation. The first experiments were conducted using a steel tether and rubber tether in gravity space. We also conducted experiment of the motion of the tethered system with a rigid body in microgravity space. The numerical solutions using the proposed methods for the modeling and formulation for the tethered system are in good agreement with the experimental results.

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de Arau´jo, Jairo Bastos, Jose´ Carlos Lima de Almeida, and Antonio Carlos Fernandes. "Installation of a Submerged Buoy for Supporting Risers (BSR) System in Campos Basin Site." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50167.

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The BSR (Buoy for Supporting Risers) concept is composed by a submerged buoy anchored to the sea bottom by tethers and intended to support risers coming from the bottom (probably SCRs — Steel Catenary Risers) and going to the floating platform (probably with flexible jumpers). For the case under analysis here, the main dimensions of the BSR prototype are 27.2 m length × 27.2 m width × 5.0 m depth. The paper describes all final full scale installation step so that the BSR may be considered a suitable technology. The installation indeed was the great challenge of this design due the size of the hull. The present work also evaluates numerically and experimentally a specific new manner to install the BSR with the support of auxiliary mooring lines among with the four tethers connected to it. One of the installation premises was to make use of Anchor Handling Supply Vessels instead of Crane Vessels. After this numerical analysis, the work went on by performing model tests that simulates the operation in a deep water model basin using 1:40 scale. The model test anticipated several problems such as the chain stopper weakness in the operation and others as discussed in this paper. As a conclusion the work was devised the most important parameters during the system installation and suggested ways to improve the methodology. In November 2009 the BSR was installed in 500 m of water depth at Congro field location, Campos Basin, offshore Brazil. The tethers were adjusted in January 2010 and in March 2010 two risers were installed. Thenceforward the last edge of this knowledge was considered over passed.

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Luharuka, Rajesh, and Peter J. Hesketh. "A Fully-Compliant, In-Plane Rotary, Bistable Micromechanism." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81220.

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A fully compliant bistable micromechanism (hereafter identified as an in-plane rotary bistable micromechanism or IPRBM) is designed to accomplish in-plane rotary motion with two stable positions. The micromechanism consists of four individually bistable mechanisms arranged in a cyclically symmetric geometry about a central proof mass. This class of bistable mechanism can be used in gate valve, optical shutter, and other switching applications. Two classes of IPRBMs are investigated in this paper. The bistable micromechanism size is less than 1 mm and fabricated by electroplating a soft magnetic material — Permalloy (80% Ni, 20% Fe) in a positive photoresist mold. Minimum feature size in the IPRBM, which corresponds to the width of flexible linkages, is 4 μm. The fabricated IPRBMs have been tested for their force-deflection response using an image based force sensing method. The test results were then compared with the simulated results obtained from a finite element model of the IPRBM. The IPRBM are shown to reversibly undergo 10 to 20 degrees of in-plane rotation and required a maximum torque of 1 to 2 μNm depending on the design. The experimental results showed good overall agreement with the design. A comparison within and between the two classes of IPRBM have been completed for three different design cases between which the tether width and aspect ratio was varied. The study showed a relative advantage of slender tethers with high aspect ratio in minimizing out-of-plane deflection. Also, the radial separation of the individual bistable mechanisms is important.

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Reports on the topic "Flexible tethers"

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Costello, Mark F., and Geoffrey W. Forst. Simulation of Two Projectiles Connected by a Flexible Tether. Fort Belvoir, VA: Defense Technical Information Center, July 2000. http://dx.doi.org/10.21236/ada382286.

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