Journal articles: 'Flexible tethers'

1

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

2

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

3

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

5

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

8

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+.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Williams, Paul, Takeo Watanabe, Chris Blanksby, Pavel Trivailo, and Hironori A. Fujii. "Libration Control of Flexible Tethers Using Electromagnetic Forces and Movable Attachment." Journal of Guidance, Control, and Dynamics 27, no. 5 (September 2004): 882–97. http://dx.doi.org/10.2514/1.1895.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Dudykevych, Valery, and Blintsov Oleksandr. "TASKS STATEMENT FOR MODERN AUTOMATIC CONTROL THEORY OF UNDERWATER COMPLEXES WITH FLEXIBLE TETHERS." EUREKA: Physics and Engineering 5 (September 30, 2016): 25–36. http://dx.doi.org/10.21303/2461-4262.2016.00158.

Full text

Abstract:

The definition of a new class of control objects is proposed. It is an underwater complex with flexible tethers (UCFT) for which there is the need to automate motion control under uncertainty and nonstationarity of own parameters and external disturbances. Classification of marine mobile objects and characteristics of the flexible tethers as UCFT elements is given. The basic UCFTs configurations that are used in the implementation of advanced underwater technologies are revealed. They include single-, double- and three-linked structures with surface or underwater support vessels and self-propelled or towed underwater vehicles. The role of mathematical modeling in tasks of motion control automation is shown. The tasks of UCFT mathematical modeling are formulated for synthesis and study of its automatic control systems. Generalized structures of mathematical models of UCFT basic elements are proposed as the basis for the creation of simulating complex to study the dynamics of its motion. The tasks of UCFT identification as a control object are formulated. Their consistent solution will help to obtain a UCFT mathematical model. The basic requirements for UCFT automatic motion control systems are determined. Their satisfaction will ensure implementation of selected underwater technology. Areas of development of synthesis methods of UCFT automatic control systems are highlighted.

APA, Harvard, Vancouver, ISO, and other styles

13

Ouellet, Jonathan, Stephanie Schorr, Asif Iqbal, Timothy J. Wilson, and David M. J. Lilley. "Orientation of Cyanine Fluorophores Terminally Attached to DNA via Long, Flexible Tethers." Biophysical Journal 101, no. 5 (September 2011): 1148–54. http://dx.doi.org/10.1016/j.bpj.2011.07.007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Ergin, A., W. G. Price, R. Randall, and P. Temarel. "Dynamic Characteristics of a Submerged, Flexible Cylinder Vibrating in Finite Water Depths." Journal of Ship Research 36, no. 02 (June 1, 1992): 154–67. http://dx.doi.org/10.5957/jsr.1992.36.2.154.

Full text

Abstract:

This paper presents experimental data and theoretical predictions of the dynamic characteristics (natural and resonance frequencies, mode shapes) of a flexible cylinder vibrating in air and at fixed positions below a free surface in water of finite depth. The flat-ended, thin cylindrical shell of overall length 1284 mm, external radius 180 mm, thickness 3 mm is made of mild steel. In the experiments, the shell was tethered (i) at 0.21, 0.23, and 0.68 m depths below the free surface in water of depth 1.6 m and (ii) at 0.25, 1.5, and 3.5 m depths in 4 m of water. The resonance frequency data recorded provide measures of the influences of free surface, cylinder position, rigid boundary, water depth, etc. occurring in the fluid-structure interaction process. The theoretical predictions are derived from a three-dimensional hydroelastic mathematical model which, through the calculations of the generalized fluid loadings, accounts for the influence of free surface and rigid boundaries, position of submerged cylinder, neutral buoyancy or, as in the present case, with tethers and buoyancy effects. An extensive comparison of results is included. The experimental restrictions of water depth, cylinder position, etc. and the fluid-structure interactions are assessed and illustrated through the calculated resonance frequency values.

APA, Harvard, Vancouver, ISO, and other styles

15

Keck, Gary E., Shawn M. Dougherty, and Kenneth A. Savin. "Intramolecular Allylstannane-Aldehyde Cyclizations: Stereochemical Results with Flexible Tethers for Reactions Forming Vinylcyclohexanols." Journal of the American Chemical Society 117, no. 23 (June 1995): 6210–23. http://dx.doi.org/10.1021/ja00128a007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Gołębiowski, Wojciech, Rafał Michalczyk, Michał Dyrek, Umberto Battista, and Kjetil Wormnes. "Validated simulator for space debris removal with nets and other flexible tethers applications." Acta Astronautica 129 (December 2016): 229–40. http://dx.doi.org/10.1016/j.actaastro.2016.08.037.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Moore, Nathan W., and Tonya L. Kuhl. "The Role of Flexible Tethers in Multiple Ligand-Receptor Bond Formation between Curved Surfaces." Biophysical Journal 91, no. 5 (September 2006): 1675–87. http://dx.doi.org/10.1529/biophysj.105.079871.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Lu, Yi, and Jeffrey L. Ram. "Predictions of flexible C-terminal tethers of bacterial proteins with the FLEXTAIL bioinformatics pipeline." International Journal of Data Mining and Bioinformatics 5, no. 2 (2011): 174. http://dx.doi.org/10.1504/ijdmb.2011.039176.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Studer, Michael K., Lazar Ivanović, Marco E. Weber, Sabrina Marti, and Stefanie Jonas. "Structural basis for DEAH-helicase activation by G-patch proteins." Proceedings of the National Academy of Sciences 117, no. 13 (March 16, 2020): 7159–70. http://dx.doi.org/10.1073/pnas.1913880117.

Full text

Abstract:

RNA helicases of the DEAH/RHA family are involved in many essential cellular processes, such as splicing or ribosome biogenesis, where they remodel large RNA–protein complexes to facilitate transitions to the next intermediate. DEAH helicases couple adenosine triphosphate (ATP) hydrolysis to conformational changes of their catalytic core. This movement results in translocation along RNA, which is held in place by auxiliary C-terminal domains. The activity of DEAH proteins is strongly enhanced by the large and diverse class of G-patch activators. Despite their central roles in RNA metabolism, insight into the molecular basis of G-patch–mediated helicase activation is missing. Here, we have solved the structure of human helicase DHX15/Prp43, which has a dual role in splicing and ribosome assembly, in complex with the G-patch motif of the ribosome biogenesis factor NKRF. The G-patch motif binds in an extended conformation across the helicase surface. It tethers the catalytic core to the flexibly attached C-terminal domains, thereby fixing a conformation that is compatible with RNA binding. Structures in the presence or absence of adenosine diphosphate (ADP) suggest that motions of the catalytic core, which are required for ATP binding, are still permitted. Concomitantly, RNA affinity, helicase, and ATPase activity of DHX15 are increased when G-patch is bound. Mutations that detach one end of the tether but maintain overall binding severely impair this enhancement. Collectively, our data suggest that the G-patch motif acts like a flexible brace between dynamic portions of DHX15 that restricts excessive domain motions but maintains sufficient flexibility for catalysis.

APA, Harvard, Vancouver, ISO, and other styles

20

Johnston, Lindsey L., Andrew J. Ursini, Nathan P. Oien, Ronald M. Supkowski, and Robert L. LaDuca. "Cation control of dimensionality in isothiocyanate coordination polymers constructed from conformationally flexible 3,3′-bipyridine tethers." Inorganica Chimica Acta 360, no. 11 (August 2007): 3619–25. http://dx.doi.org/10.1016/j.ica.2007.05.004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

KECK, G. E., S. M. DOUGHERTY, and K. A. SAVIN. "ChemInform Abstract: Intramolecular Allylstannane-Aldehyde Cyclizations: Stereochemical Results with Flexible Tethers for Reactions Forming Vinylcyclohexanols." ChemInform 26, no. 40 (August 17, 2010): no. http://dx.doi.org/10.1002/chin.199540111.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Wang, Xinxin, and Gaudenz Danuser. "Remeshing flexible membranes under the control of free energy." PLOS Computational Biology 18, no. 12 (December 5, 2022): e1010766. http://dx.doi.org/10.1371/journal.pcbi.1010766.

Full text

Abstract:

Cell membranes are flexible and often undergo large-scale morphological changes during processes like mitosis, protrusion and retraction, or vesicle fusion. Mathematical modeling of cell membranes depends on a representation of the free-form surface by discrete meshes. During morphological changes, these meshes must be adjusted under the minimization of the total free energy. Current methodology for meshing is limited in one of two ways: 1) Free energy-dependent methods have no restriction on the mesh geometry. The resulting irregular meshes cause artifacts in follow-up models of morphodynamics. 2) Geometry-dependent methods maintain mesh quality but violate the physics of free energy minimization. To fill this gap, we regulate mesh geometries via a free-energy-determined remeshing process: adding and removing mesh elements upon morphological changes based on barrier crossings in a double-barrier potential between neighboring vertices in the meshes. We test the method’s robustness by reproducing the morphodynamics of red blood cells and vesicle fusions; and we demonstrate the method’s adaptability by simulating the formation of filopodia, lamellipodia and invaginations. Finally, we use the method to study a mechanical decoupling effect of two connected membrane tethers that has been recently observed experimentally, but has not been mechanistically explained in the context of a complete membrane surface. We propose a biophysical model that strengthens the decoupling effect and broadens the original interpretation of the experiment. The method is developed in C/Matlab and distributed via https://github.com/DanuserLab/biophysicsModels.

APA, Harvard, Vancouver, ISO, and other styles

23

Blake, Karyn M., Lindsey L. Johnston, Maxwell A. Braverman, Joseph H. Nettleman, Laura K. Sposato, and Robert L. LaDuca. "Divalent metal 1,3-phenylenediacetate coordination polymers with rigid or flexible dipyridyl tethers: Chains, layers, and interpenetrated networks." Inorganica Chimica Acta 363, no. 10 (June 2010): 2233–42. http://dx.doi.org/10.1016/j.ica.2010.03.029.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Barnwal, Ravi P., Mandeep Kaur, Alec Heckert, Janeka Gartia, and Gabriele Varani. "Comparative structure, dynamics and evolution of acyl-carrier proteins from Borrelia burgdorferi, Brucella melitensis and Rickettsia prowazekii." Biochemical Journal 477, no. 2 (January 31, 2020): 491–508. http://dx.doi.org/10.1042/bcj20190797.

Full text

Abstract:

Acyl carrier proteins (ACPs) are small helical proteins found in all kingdoms of life, primarily involved in fatty acid and polyketide biosynthesis. In eukaryotes, ACPs are part of the fatty acid synthase (FAS) complex, where they act as flexible tethers for the growing lipid chain, enabling access to the distinct active sites in FAS. In the type II synthesis systems found in bacteria and plastids, these proteins exist as monomers and perform various processes, from being a donor for synthesis of various products such as endotoxins, to supplying acyl chains for lipid A and lipoic acid FAS (quorum sensing), but also as signaling molecules, in bioluminescence and activation of toxins. The essential and diverse nature of their functions makes ACP an attractive target for antimicrobial drug discovery. Here, we report the structure, dynamics and evolution of ACPs from three human pathogens: Borrelia burgdorferi, Brucella melitensis and Rickettsia prowazekii, which could facilitate the discovery of new inhibitors of ACP function in pathogenic bacteria.

APA, Harvard, Vancouver, ISO, and other styles

25

Stoops, James K., Z. Hong Zhou, John P. Schroeter, Steven J. Kolodziej, R. Holland Cheng, Timothy S. Baker, Diane L. B. McCarthy, Mohammed A. Yazdi, Cheol-Young Maeng, and Lester J. Reed. "On The Unique Structural Organization of the Saccharomyces Cerevisiae Pyruvate Dehydrogenase Complex." Microscopy and Microanalysis 4, S2 (July 1998): 954–55. http://dx.doi.org/10.1017/s1431927600024892.

Full text

Abstract:

Dihydrohpoamide acetyl transferase (E2), a catalytic and structural component of a multienzyme complex that catalyzes the oxidative decarboxylation of pyruvate, forms the central core to which the other components are bound. We have utilized protein engineering and 3-D electron microscopy to study the structural organization of the largest multienzyme complex known (Mr ∼ 107). The structures of the truncated 60-mer core (tE2) and complexes of the tE2 associated with a binding protein (BP), and the BP associated with its dihydrohpoamide dehydrogenase (BP'E3) and the intact E2 associated with BP and the pyruvate dehydrogenase (E1) were determined (Figs. 1 and 2). The tE2 core is a pentagonal dodecahedron consisting of 20 cone-shaped trimers interconnected by 30 bridges.Previous studies have given rise to the generally accepted belief that BP and BP'E3 components are bound on the outside of the E2 scaffold and that E1 is similarly bound to the core in variable positions by flexible tethers.

APA, Harvard, Vancouver, ISO, and other styles

26

Benavente, Juan L., Dritan Siliqi, Lourdes Infantes, Laura Lagartera, Alberto Mills, Federico Gago, Noemí Ruiz-López, Miguel A. Botella, María J. Sánchez-Barrena, and Armando Albert. "The structure and flexibility analysis of the Arabidopsis synaptotagmin 1 reveal the basis of its regulation at membrane contact sites." Life Science Alliance 4, no. 10 (August 18, 2021): e202101152. http://dx.doi.org/10.26508/lsa.202101152.

Full text

Abstract:

Non-vesicular lipid transfer at ER and plasma membrane (PM) contact sites (CS) is crucial for the maintenance of membrane lipid homeostasis. Extended synaptotagmins (E-Syts) play a central role in this process as they act as molecular tethers of ER and PM and as lipid transfer proteins between these organelles. E-Syts are proteins constitutively anchored to the ER through an N-terminal hydrophobic segment and bind the PM via a variable number of C-terminal C2 domains. Synaptotagmins (SYTs) are the plant orthologous of E-Syts and regulate the ER–PM communication in response to abiotic stress. Combining different structural and biochemical techniques, we demonstrate that the binding of SYT1 to lipids occurs through a Ca2+-dependent lipid-binding site and by a site for phosphorylated forms of phosphatidylinositol, thus integrating two different molecular signals in response to stress. In addition, we show that SYT1 displays three highly flexible hinge points that provide conformational freedom to facilitate lipid extraction, protein loading, and subsequent transfer between PM and ER.

APA, Harvard, Vancouver, ISO, and other styles

27

Foster, Brittni M., Daniel Rosenberg, Henry Salvo, Kasie L. Stephens, Brittania J. Bintz, Michal Hammel, Tom Ellenberger, Maria D. Gainey, and Jamie R. Wallen. "Combined Solution and Crystal Methods Reveal the Electrostatic Tethers That Provide a Flexible Platform for Replication Activities in the Bacteriophage T7 Replisome." Biochemistry 58, no. 45 (October 29, 2019): 4466–79. http://dx.doi.org/10.1021/acs.biochem.9b00525.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Alexander, D. E. "Wind tunnel studies of turns by flying dragonflies." Journal of Experimental Biology 122, no. 1 (May 1, 1986): 81–98. http://dx.doi.org/10.1242/jeb.122.1.81.

Full text

Abstract:

High-speed movies of dragonflies turning in flight on flexible tethers show that there are two distinct modes of turning. In the ‘conventional’ mode, dragonflies use left-right asymmetries in the wing stroke amplitude, and occasionally in the angle of attack, to produce more lift and thrust on one side than the other. This causes the animal to roll into a bank, so that the lift vector has a sideward component; this sideward component produces the turn, much as in an airplane. This type of turn is probably most useful during fast forward flight. The second mode of turning in the ‘yaw turn’. Yaw turns are accomplished without banking, and the dragonfly's long axis may turn more than 90 degrees in the period of two wing strokes. The kinematics of this turn could not be as closely analysed, but it appears that dragonflies use drag on the inner wing upstroke and the outer wing downstroke to turn, much like pivoting a rowing boat. This turn may be hampered by drag on the abdomen during fast forward flight and would be most useful at low speeds or during hovering.

APA, Harvard, Vancouver, ISO, and other styles

29

Wang, Zhiming, Zhu Qiao, Sheng Ye, and Rongguang Zhang. "Structure of a double-domain phosphagen kinase reveals an asymmetric arrangement of the tandem domains." Acta Crystallographica Section D Biological Crystallography 71, no. 4 (March 26, 2015): 779–89. http://dx.doi.org/10.1107/s1399004715001169.

Full text

Abstract:

Tandem duplications and fusions of single genes have led to magnificent expansions in the divergence of protein structures and functions over evolutionary timescales. One of the possible results is polydomain enzymes with interdomain cooperativities, few examples of which have been structurally characterized at the full-length level to explore their innate synergistic mechanisms. This work reports the crystal structures of a double-domain phosphagen kinase in both apo and ligand-bound states, revealing a novel asymmetric L-shaped arrangement of the two domains. Unexpectedly, the interdomain connections are not based on a flexible hinge linker but on a rigid secondary-structure element: a long α-helix that tethers the tandem domains in relatively fixed positions. Besides the connective helix, the two domains also contact each other directly and form an interdomain interface in which hydrogen bonds and hydrophobic interactions further stabilize the L-shaped domain arrangement. Molecular-dynamics simulations show that the interface is generally stable, suggesting that the asymmetric domain arrangement crystallographically observed in the present study is not a conformational state simply restrained by crystal-packing forces. It is possible that the asymmetrically arranged tandem domains could provide a structural basis for further studies of the interdomain synergy.

APA, Harvard, Vancouver, ISO, and other styles

30

Reboux, S., G. Richardson, and O. E. Jensen. "Bond tilting and sliding friction in a model of cell adhesion." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2090 (December 4, 2007): 447–67. http://dx.doi.org/10.1098/rspa.2007.0210.

Full text

Abstract:

As a simple theoretical model of a cell adhering to a biological interface, we consider a rigid cylinder moving in a viscous shear flow near a wall. Adhesion forces arise through intermolecular bonds between receptors on the cell and their ligands on the wall, which form flexible tethers that can stretch and tilt as the base of the cell moves past the wall; binding kinetics is assumed to follow a standard model for slip bonds. By introducing a finite resistance to bond tilting, we use our model to explore the territory between previous theoretical models that allow for either zero or infinite resistance to bond rotation. A microscale calculation (for two parallel sliding plates) reveals a nonlinear force–speed relation arising from bond formation, tilting and breakage. Two distinct types of macroscale cell motion are then predicted: either bonds adhere strongly and the cell rolls (or tank treads) over the wall without slipping, or the cell moves near its free-stream speed with bonds providing weak frictional resistance to sliding. The model predicts bistability between these two states, implying that at critical shear rates the system can switch abruptly between rolling and free sliding, and suggesting that sliding friction arising through bond tilting may play a significant dynamical role in some cell-adhesion applications.

APA, Harvard, Vancouver, ISO, and other styles

31

Martin, David P., Maxwell A. Braverman, and Robert L. LaDuca. "Two- and Three-Dimensional Divalent Metal Isophthalate Coordination Polymers Incorporating Flexible Bispyridylmethylpiperazine Tethers: Structure Direction through Coordination Geometry Preferences, Carboxylate Binding Mode, and Ligand Conformation." Crystal Growth & Design 7, no. 12 (December 2007): 2609–19. http://dx.doi.org/10.1021/cg700664u.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Oparin, Peter B., Kirill D. Nadezhdin, Antonina A. Berkut, Alexander S. Arseniev, Eugene V. Grishin, and Alexander A. Vassilevski. "Structure of purotoxin-2 from wolf spider: modular design and membrane-assisted mode of action in arachnid toxins." Biochemical Journal 473, no. 19 (September 27, 2016): 3113–26. http://dx.doi.org/10.1042/bcj20160573.

Full text

Abstract:

Traditionally, arachnid venoms are known to contain two particularly important groups of peptide toxins. One is disulfide-rich neurotoxins with a predominance of β-structure that specifically target protein receptors in neurons or muscle cells. The other is linear cationic cytotoxins that form amphiphilic α-helices and exhibit rather non-specific membrane-damaging activity. In the present paper, we describe the first 3D structure of a modular arachnid toxin, purotoxin-2 (PT2) from the wolf spider Alopecosa marikovskyi (Lycosidae), studied by NMR spectroscopy. PT2 is composed of an N-terminal inhibitor cystine knot (ICK, or knottin) β-structural domain and a C-terminal linear cationic domain. In aqueous solution, the C-terminal fragment is hyper-flexible, whereas the knottin domain is very rigid. In membrane-mimicking environment, the C-terminal domain assumes a stable amphipathic α-helix. This helix effectively tethers the toxin to membranes and serves as a membrane-access and membrane-anchoring device. Sequence analysis reveals that the knottin + α-helix architecture is quite widespread among arachnid toxins, and PT2 is therefore the founding member of a large family of polypeptides with similar structure motifs. Toxins from this family target different membrane receptors such as P2X in the case of PT2 and calcium channels, but their mechanism of action through membrane access may be strikingly similar.

APA, Harvard, Vancouver, ISO, and other styles

33

Shan, Minghe, and Lingling Shi. "Comparison of Tethered Post-Capture System Models for Space Debris Removal." Aerospace 9, no. 1 (January 11, 2022): 33. http://dx.doi.org/10.3390/aerospace9010033.

Full text

Abstract:

The space debris problem poses a huge threat to operational satellites and has to be addressed. Multiple removal methods have been proposed to keep Earth’s orbit stable. Flexible connection capturing methods, such as the harpoon system, tether–gripper system and the net system, are potential candidate methods for space debris removal in the future. However, the tethered system is usually assumed as a dumbbell model where two end masses are connected by a rigid bar. This traditional model is not accurate enough to predict the motion of the target, neither the whole system. In this paper, three models, namely the modified dumbbell model, lumped-mass model and the ANCF model, to describe a tethered post-capture system for space debris removal are described and compared. Moreover, modal analysis of the tethered system is performed, and an analytical solution of the system’s natural frequency is derived. In addition, two configurations of the tethered system, namely the single tether configuration and the sub-tether configuration are simulated and compared based on three models, respectively. Finally, the influence on the chaser satellite by the initial angular velocity of the target is analyzed.

APA, Harvard, Vancouver, ISO, and other styles

34

Nagaratnam, Nirupa, Jose M. Martin-Garcia, Jay-How Yang, Matthew R. Goode, Gihan Ketawala, Felicia M. Craciunescu, James D. Zook, et al. "Structural and biophysical properties of FopA, a major outer membrane protein of Francisella tularensis." PLOS ONE 17, no. 8 (August 1, 2022): e0267370. http://dx.doi.org/10.1371/journal.pone.0267370.

Full text

Abstract:

Francisella tularensis is an extremely infectious pathogen and a category A bioterrorism agent. It causes the highly contagious zoonosis, Tularemia. Currently, FDA approved vaccines against tularemia are unavailable. F. tularensis outer membrane protein A (FopA) is a well-studied virulence determinant and protective antigen against tularemia. It is a major outer membrane protein (Omp) of F. tularensis. However, FopA-based therapeutic intervention is hindered due to lack of complete structural information for membrane localized mature FopA. In our study, we established recombinant expression, monodisperse purification, crystallization and X-ray diffraction (~6.5 Å) of membrane localized mature FopA. Further, we performed bioinformatics and biophysical experiments to unveil its structural organization in the outer membrane. FopA consists of 393 amino acids and has less than 40% sequence identity to known bacterial Omps. Using comprehensive sequence alignments and structure predictions together with existing partial structural information, we propose a two-domain organization for FopA. Circular dichroism spectroscopy and heat modifiability assay confirmed FopA has a β-barrel domain consistent with alphafold2’s prediction of an eight stranded β-barrel at the N-terminus. Small angle X-ray scattering (SAXS) and native-polyacrylamide gel electrophoresis revealed FopA purified in detergent micelles is predominantly dimeric. Molecular density derived from SAXS at 31 Å shows putative dimeric N-terminal β-barrels surrounded by detergent corona and connected to C-terminal domains via flexible linker. Disorder analysis predicts N- and C-terminal domains are interspersed by a long intrinsically disordered region and alphafold2 predicts this region to be largely unstructured. Taken together, we propose a dimeric, two-domain organization of FopA in the outer membrane: the N-terminal β-barrel is membrane embedded, provides dimerization interface and tethers to membrane extrinsic C-terminal domain via long flexible linker. Structure determination of membrane localized mature FopA is essential to understand its role in pathogenesis and develop anti-tularemia therapeutics. Our results pave the way towards it.

APA, Harvard, Vancouver, ISO, and other styles

35

Roth, Amy F., Irene Papanayotou, and Nicholas G. Davis. "The yeast kinase Yck2 has a tripartite palmitoylation signal." Molecular Biology of the Cell 22, no. 15 (August 2011): 2702–15. http://dx.doi.org/10.1091/mbc.e11-02-0115.

Full text

Abstract:

The yeast kinase Yck2 tethers to the cytoplasmic surface of the plasma membrane through dual palmitoylation of its C-terminal Cys-Cys dipeptide, mediated by the Golgi-localized palmitoyl-transferase Akr1. Here, the Yck2 palmitoylation signal is found to consist of three parts: 1) a 10-residue-long, conserved C-terminal peptide (CCTP) that includes the C-terminal Cys-Cys dipeptide; 2) the kinase catalytic domain (KD); and mapping between these two elements; and 3) a 176-residue-long, poorly conserved, glutamine-rich sequence. The CCTP, which contains the C-terminal cysteines as well as an important Phe-Phe dipeptide, likely serves as an Akr1 recognition element, because CCTP mutations disrupt palmitoylation within a purified in vitro palmitoylation system. The KD contribution appears to be complex with roles for both KD activity (e.g., Yck2-mediated phosphorylation) and structure (e.g., Akr1 recognition elements). KD and CCTP mutations are strongly synergistic, suggesting that, like the CCTP, the KD may also participate at the Yck2-Akr1 recognition step. The long, glutamine-rich domain, which is located between the KD and CCTP, is predicted to be intrinsically disordered and may function as a flexible, interdomain linker, allowing a coupled interaction of the KD and CCTP with Akr1. Multipart palmitoylation signals may prove to be a general feature of this large class of palmitoylation substrates. These soluble proteins have no clear means of accessing membranes and thus may require active capture out of the cytoplasm for palmitoylation by their membrane-localized transferases.

APA, Harvard, Vancouver, ISO, and other styles

36

Bainum, P. M., C. M. Diarra, and V. K. Kumar. "Shuttle-tethered subsatellite system stability with a flexible massive tether." Journal of Guidance, Control, and Dynamics 8, no. 2 (March 1985): 230–34. http://dx.doi.org/10.2514/3.19964.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Hong, Aaron Aw Teik, and Renuganth Varatharajoo. "Investigation on a Flexible Tether Slackness Based on In- and Out-of Plane Libration Angles." Applied Mechanics and Materials 225 (November 2012): 411–16. http://dx.doi.org/10.4028/www.scientific.net/amm.225.411.

Full text

Abstract:

Tethered Satellite Systems (TSS) have been used in various applications such as in performing space interferometry, orbit transfer and other relevant fields. As far as the operation system of a TSS is concerned, it is crucial to ensure that the tether will not go slack as its slackness would adversely affects the overall operation outcome due to an undesirable system dynamics. Therefore, it is important to investigate the types of conditions that will cause the tether slackness. Investigations on in-plane and out-of plane libration angles can be utilized to measure at what point that the tether will go slack. Based on previous research works, usually a rigid tether comprising of a uniformed mass is considered while the connecting two satellites are regarded as point masses in order to simplify the governing dynamics equation of motion. However, in order to develop a much more accurate modeling, a flexible tether is chosen by further incorporating the reeling mechanism, attitude dynamics of rigid bodies and tether deformations. Furthermore, a tether has a tendency to go slack if the in-plane and out-of plane libration angle exceeds 65° and 60° respectively regardless of the types of tether utilized whether it being a rigid or a flexible one. Thus, the tension of the tether will serves as a constraint and plotted against the in-plane and out-of plane libration motions that would be attained via the generalized forces. The results will then be analyzed to establish in-plane and out-of plane libration boundaries. Subsequently, the in-plane and out-of plane operation contrains are established for TSS corresponding to a reference mission.

APA, Harvard, Vancouver, ISO, and other styles

38

Gliessman, P. M., K. Y. Pau, J. D. Hill, and H. G. Spies. "Chronic push-pull brain perfusion in unrestrained rhesus macaques." Journal of Applied Physiology 61, no. 6 (December 1, 1986): 2273–79. http://dx.doi.org/10.1152/jappl.1986.61.6.2273.

Full text

Abstract:

A system was developed to permit perfusion of local brain regions and simultaneous peripheral blood sampling in free-moving caged monkeys. The system comprises a calvarial headpiece that contains multiple push-pull cannulas (PPC), a flexible stainless steel tether, a four-channel fluid swivel, and a surgical procedure for simultaneous multisite brain cannulation. Rhesus macaques were fitted surgically with an indwelling jugular catheter and PPC directed into the third ventricle, median eminence, and preoptic area. These animals were tethered for periods of 14–70 h during which brain perfusates and peripheral blood samples were collected at 10- to 30-min intervals through the tether-swivel assembly. Levels and pulsatile patterns of gonadotropin-releasing hormone in 10-min perfusate samples and luteinizing hormone and cortisol in sequential plasma samples were quantified by specific radioimmunoassays. The normal endocrine profiles in these animals suggest that this system provides a valuable method to study patterns of neurosecretions in an unrestrained simian.

APA, Harvard, Vancouver, ISO, and other styles

39

Wei, Cheng, Hao Liu, Chunlin Tan, Yongjian Liu, and Yang Zhao. "Rapid attitude maneuver of the space tether net capture system using active disturbance rejection control." Mechanical Sciences 10, no. 2 (December 4, 2019): 575–87. http://dx.doi.org/10.5194/ms-10-575-2019.

Full text

Abstract:

Abstract. The space tether net capture system is a spacecraft system with a mounting tether net for capturing targets. It has the advantages of reusability and the adaptability to capture varying targets with different geometries or flying-motion statuses. However, due to its flexible tether net, the system shows strong nonlinearity, which makes it difficult to achieve the desired control performance for rapid and accurate maneuvering; moreover, this limits the ability of the tether net system to capture fast-moving targets. This paper focused on the maneuver controller design of the space capture system with a large flexible tether net. Firstly, based on the absolute node coordinate method, the dynamic model of the space tether net system is established, which can accurately describe the geometric and material nonlinearities of the space tether net. Then, a two-loop active disturbance rejection control is proposed for the rapid and high-precision maneuvering of the flexible system; meanwhile the second-order extended state observer is designed to estimate and compensate for the tether net vibration disturbance. The simulation validated the proposed control, which could complete the rapid and accurate maneuvering and also compensate for the disturbance caused by the vibration of the flexible tether net.

APA, Harvard, Vancouver, ISO, and other styles

40

Puig-Suari, Jordi, James M. Logunski, and Steven G. Tragesser. "Aerocapture with a flexible tether." Journal of Guidance, Control, and Dynamics 18, no. 6 (November 1995): 1305–12. http://dx.doi.org/10.2514/3.21546.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

FAN, Jixiang, Youki YANO, Hironori A. FUJII, and Kazuki OHHATA. "2D36 Micro Tension Actuator for Vibration Suppression of Tethered Flexible Space Structures : Experimental Study." Proceedings of the Symposium on the Motion and Vibration Control 2010 (2010): _2D36–1_—_2D36–9_. http://dx.doi.org/10.1299/jsmemovic.2010._2d36-1_.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Aguzzi, Jacopo, Jan Albiez, Sascha Flögel, Olav Rune Godø, Endre Grimsbø, Simone Marini, Olaf Pfannkuche, et al. "A Flexible Autonomous Robotic Observatory Infrastructure for Bentho-Pelagic Monitoring." Sensors 20, no. 6 (March 13, 2020): 1614. http://dx.doi.org/10.3390/s20061614.

Full text

Abstract:

This paper presents the technological developments and the policy contexts for the project “Autonomous Robotic Sea-Floor Infrastructure for Bentho-Pelagic Monitoring” (ARIM). The development is based on the national experience with robotic component technologies that are combined and merged into a new product for autonomous and integrated ecological deep-sea monitoring. Traditional monitoring is often vessel-based and thus resource demanding. It is economically unviable to fulfill the current policy for ecosystem monitoring with traditional approaches. Thus, this project developed platforms for bentho-pelagic monitoring using an arrangement of crawler and stationary platforms at the Lofoten-Vesterålen (LoVe) observatory network (Norway). Visual and acoustic imaging along with standard oceanographic sensors have been combined to support advanced and continuous spatial-temporal monitoring near cold water coral mounds. Just as important is the automatic processing techniques under development that have been implemented to allow species (or categories of species) quantification (i.e., tracking and classification). At the same time, real-time outboard processed three-dimensional (3D) laser scanning has been implemented to increase mission autonomy capability, delivering quantifiable information on habitat features (i.e., for seascape approaches). The first version of platform autonomy has already been tested under controlled conditions with a tethered crawler exploring the vicinity of a cabled stationary instrumented garage. Our vision is that elimination of the tether in combination with inductive battery recharge trough fuel cell technology will facilitate self-sustained long-term autonomous operations over large areas, serving not only the needs of science, but also sub-sea industries like subsea oil and gas, and mining.

APA, Harvard, Vancouver, ISO, and other styles

43

Churkin, V. M., T. Yu Churkina, and A. M. Girin. "Mathematical Model of Spatial Motion of the Controlled Parachute-Tether System of the Wind Kite Type." Vestnik IzhGTU imeni M.T. Kalashnikova 24, no. 4 (2021): 17–24. http://dx.doi.org/10.22213/2413-1172-2021-4-17-24.

Full text

Abstract:

Mathematical modeling is created for the mathematical task of spatial motion of the controlled parachute-tether system of the “wind kite” type. The mathematical model parachute-tether system consists of a model of the main parachute and a model of the braking parachute. The parachutes are connected by the tether. The model of the main parachute is supposed to be the solid body. This solid body has two planes of symmetry. The braking parachute is the solid body with axial symmetry. The tether model is an absolutely flexible elastic thread. The tether is connected by ideal hinges with the main parachute and braking parachute. The control of the main parachute is carried out by changing the length of the control slings. Changing the length causes deformation of the dome. This is the reason for the change in its aerodynamics. Maneuvering of the main parachute occurs in the vertical plane, when the length of the control slings changes simultaneously. Maneuvering of the main parachute in space is carried out when the length of the control slings changes, when the slings are given a travel difference. The system of dynamic and kinematic equations is designed for calculating the controlled spatial movement of the main parachute, braking parachute and tether. The option exists when the mass of the tether and the forces applied to the tether cannot be neglected. The motion of the tether is represented by the equations of motion of an absolutely flexible elastic thread in projections on the axis of a natural trihedron. The mathematical model is represented by a system of ordinary differential equations and partial differential equations. The problem is solved using various numerical methods. The solution is possible with the help of an integrated numerical and analytical approach as well.

APA, Harvard, Vancouver, ISO, and other styles

44

Takayama, Satoshi, Shoichiro Takehara, and Ryota Yuasa. "Contact Analysis of Mobility Devices Based on Tension." Modelling 2, no. 3 (August 20, 2021): 370–84. http://dx.doi.org/10.3390/modelling2030020.

Full text

Abstract:

Advances in space technology have opened up opportunities for human beings to work in outer space. It is expected that the upsizing of manned space facilities, such as the International Space Station, will further this trend. A unique means of transportation is necessary to ensure that human beings can move about effectively in microgravity environments. Here, we propose a tether-based mobility system that moves the user by winding a tether attached to a structure at the destination. To overcome the attitude instability of the user during tether winding, the Tether Space Mobility Device (TSMD) attitude control method for winding a tether is applied and examined through numerical analysis. The proposed analytical model for motion analysis consists of one flexible body and three rigid bodies. The contact force between the tether and the TSMD inlet is determined. Using the numerical analysis model, we investigated the effect of slit shape during tether extension and winding.

APA, Harvard, Vancouver, ISO, and other styles

45

Zhai, Guang, Yue Qiu, Bin Liang, and Cheng Li. "On-orbit capture with flexible tether–net system." Acta Astronautica 65, no. 5-6 (September 2009): 613–23. http://dx.doi.org/10.1016/j.actaastro.2009.03.011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Grassucci, Robert, Terence Wagenknecht, Gary A. Radke, and Thomas E. Roche. "Cryoelectron Microscopy of Frozen-Hydrated Pyruvate Dehydrogenase Complexes." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 260–61. http://dx.doi.org/10.1017/s0424820100180057.

Full text

Abstract:

Pyruvate dehydrogenase complexes (PDC’s) from both prokaryotes and eukaryotes exist as large multisubunit assemblies in which one of the component enzymes, dihydrolipoyl transacetylase (E2), forms a structural core that possesses multiple binding sites on its surface for the pyruvate dehydrogenase (E1) and dihydrolipoyl dehydrogenase (E3) components. We are investigating the structure of PDC’s from E. coli and bovine heart by cryoelectron microscopy of frozen-hydrated native complexes and various types of subcomplexes prepared in vitro. Fields of frozen-hydrated PDC from E. coli and bovine heart are shown in Figures 1 and 2 respectively. In many images of the E. coli PDC (M.W. ∽ 5 × 106) the E2 core is visible as a dense square or rectangular mass at the center of the images (see inset in Fig. 1). The E1 and E3 components surround the E2 core, and do not appear to form a symmetrical pattern. Furthermore, there are often apparent gaps of up to several nanometers separating the bound subunits from the surface of the core. These observations suggest that the E1 and/or E3 are linked to the E2 core by flexible polypeptide ‘tethers’ which could be important in the mechanism of active site coupling. Similar observations apply to the images of the larger PDC from bovine heart (M.W. ∽ 9 × 106).Selected images of frozen-hydrated E2 cores isolated from E. coli and heart PDC are shown in Figures 3 and 4. The E. coli E2 core consists of 24 identical polypeptides arranged with octahedral symmetry, whereas the larger heart core complex consists of about 60 identical polypeptides apparently arranged with icosahedral symmetry (another component, present in a few copies and referred to as component X, also appears to be integrated into the core complex). Each E2 polypeptide possesses specialized domains (three in E. coli. two in heart) which contain the lipoic acid cofactor and are thought to be involved in coordinating the sequence of reactions catalyzed. The E. coli E2 cores often appear surrounded by a faint “fuzz” extending out from the surface by about 10 nm which we attribute to the lipoyl-bearing domains. Independent biochemical and biophysical observations are consistent with this interpretation. The larger heart E2 cores exhibit three main image types that probably correspond to views approximately along 5-fold, 3-fold and 2-fold symmetry axes. The fuzzy material observed surrounding the E. coli cores is not readily visible in the heart E2, probably because there are fewer lipoyl-bearing domains and because they occupy a much larger volume than in E. coli. Methodologies for characterizing the spatial distribution of the lipoyl-bearing domains by EM, such as labeling them with monoclonal antibodies, are being pursued.

APA, Harvard, Vancouver, ISO, and other styles

47

Qing-quan, Chen, Zhang Qing-bin, and Tang Qian-gang. "Dynamic Modeling and Ground Test of Tethered-net." MATEC Web of Conferences 220 (2018): 07003. http://dx.doi.org/10.1051/matecconf/201822007003.

Full text

Abstract:

Flexible tethered-net, a new kind of structure for advanced concepts in space exploration, has special potential application such as capturing space debris and building huge antenna. A critical issue in the design and analysis of space net system is deployment of modelling technology. The dynamics behaviour of flexible net systems is investigated based on finite segment approach in this paper. The flexible net is modelled as a series of collected semi-damp springs with masses lumped at appropriated nodes. Besides, a comprehensive study on a model for the tethered-net based on absolute nodal coordinates formulation (ANCF) is provided. Simulations show that the results based on the ANCF modelling method present a good agreement with that based on the conventional semi–spring damper modelling method. Then the flexible multibody dynamics models has been verified by comparison with ground experiment.

APA, Harvard, Vancouver, ISO, and other styles

48

Aslanov, Vladimir S., and Vadim V. Yudintsev. "Behavior of tethered debris with flexible appendages." Acta Astronautica 104, no. 1 (November 2014): 91–98. http://dx.doi.org/10.1016/j.actaastro.2014.07.028.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

LI, Aijun, Jingchen LI, Changqing WANG, and Zhe DONG. "Study on Flexible Tether Critical Length at Equilibrium State." Chinese Journal of Space Science 36, no. 3 (2016): 373. http://dx.doi.org/10.11728/cjss2016.03.373.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Takehara, Shoichiro, Yu Uematsu, and Wataru Miyaji. "Tether Space Mobility Device Attitude Control during Tether Extension and Winding." Machines 6, no. 4 (November 22, 2018): 61. http://dx.doi.org/10.3390/machines6040061.

Full text

Abstract:

Recently, advancements in space technology have opened up more opportunities for human beings to work in outer space. It is expected that upsizing of manned space facilities, such as the International Space Station, will further this trend. Therefore, a unique means of transportation is necessary to ensure that human beings can move about effectively in microgravity environments. In the present study, we propose a tether-based mobility system, which moves the user by winding a tether attached to a structure at the destination. However, there is a problem in that the attitude of the user becomes unstable during winding of the tether. Therefore, a Tether Space Mobility Device (TSMD) attitude control method for winding a tether is examined through numerical analysis. The proposed analytical model consists of one flexible body and three rigid bodies. The contact force between the tether and the inlet is considered. We verified the validity of the proposed model through experiments. Furthermore, we proposed a TSMD attitude control method during tether winding while focusing on changes in the system’s rotational kinetic energy. Using the proposed analytical model, the angular velocity of a rigid body system is confirmed to converge to 0 deg/s when control is applied.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Flexible tethers'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles