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Статті в журналах з теми "Gliding force"
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Miyata, Makoto, William S. Ryu, and Howard C. Berg. "Force and Velocity of Mycoplasma mobile Gliding." Journal of Bacteriology 184, no. 7 (April 1, 2002): 1827–31. http://dx.doi.org/10.1128/jb.184.7.1827-1831.2002.
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ABSTRACT The effects of temperature and force on the gliding speed of Mycoplasma mobile were examined. Gliding speed increased linearly as a function of temperature from 0.46 μm/s at 11.5°C to 4.0 μm/s at 36.5°C. A polystyrene bead was attached to the tail of M. mobile using a polyclonal antibody raised against whole M. mobile cells. Cells attached to beads glided at the same speed as cells without beads. When liquid flow was applied in a flow chamber, cells reoriented and moved upstream with reduced speeds. Forces generated by cells at various gliding speeds were calculated by multiplying their estimated frictional drag coefficients with their velocities relative to the liquid. The gliding speed decreased linearly with force. At zero speed, the force measurements extrapolated to 26 pN at 22.5 and 27.5°C. At zero force, the speed extrapolated to 2.3 and 3.3 μm/s at 22.5 and 27.5°C, respectively—the same speeds as those observed for free gliding cells. Cells attached to beads were also trapped by an optical tweezer, and the stall force was measured to be 26 to 28 pN (17.5 to 27.5°C). The gliding speed depended on temperature, but the maximum force did not, suggesting that the mechanism is composed of at least two steps, one that generates force and another that allows displacement. Other implications of these results are discussed.
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Bahlman, Joseph W., Sharon M. Swartz, Daniel K. Riskin, and Kenneth S. Breuer. "Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels ( Glaucomys sabrinus )." Journal of The Royal Society Interface 10, no. 80 (March 6, 2013): 20120794. http://dx.doi.org/10.1098/rsif.2012.0794.
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Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60–125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels ( Glaucomys sabrinus ) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight.
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Sabass, Benedikt, Matthias D. Koch, Guannan Liu, Howard A. Stone, and Joshua W. Shaevitz. "Force generation by groups of migrating bacteria." Proceedings of the National Academy of Sciences 114, no. 28 (June 27, 2017): 7266–71. http://dx.doi.org/10.1073/pnas.1621469114.
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From colony formation in bacteria to wound healing and embryonic development in multicellular organisms, groups of living cells must often move collectively. Although considerable study has probed the biophysical mechanisms of how eukaryotic cells generate forces during migration, little such study has been devoted to bacteria, in particular with regard to the question of how bacteria generate and coordinate forces during collective motion. This question is addressed here using traction force microscopy. We study two distinct motility mechanisms of Myxococcus xanthus, namely, twitching and gliding. For twitching, powered by type-IV pilus retraction, we find that individual cells exert local traction in small hotspots with forces on the order of 50 pN. Twitching bacterial groups also produce traction hotspots, but with forces around 100 pN that fluctuate rapidly on timescales of <1.5 min. Gliding, the second motility mechanism, is driven by lateral transport of substrate adhesions. When cells are isolated, gliding produces low average traction on the order of 1 Pa. However, traction is amplified approximately fivefold in groups. Advancing protrusions of gliding cells push, on average, in the direction of motion. Together, these results show that the forces generated during twitching and gliding have complementary characters, and both forces have higher values when cells are in groups.
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Seto, Shintaro, Atsuko Uenoyama, and Makoto Miyata. "Identification of a 521-Kilodalton Protein (Gli521) Involved in Force Generation or Force Transmission for Mycoplasma mobile Gliding." Journal of Bacteriology 187, no. 10 (May 15, 2005): 3502–10. http://dx.doi.org/10.1128/jb.187.10.3502-3510.2005.
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ABSTRACT Several mycoplasma species are known to glide on solid surfaces such as glass in the direction of the membrane protrusion, but the mechanism underlying this movement is unknown. To identify a novel protein involved in gliding, we raised monoclonal antibodies against a detergent-insoluble protein fraction of Mycoplasma mobile, the fastest glider, and screened the antibodies for inhibitory effects on gliding. Five monoclonal antibodies stopped the movement of gliding mycoplasmas, keeping them on the glass surface, and all of them recognized a large protein in immunoblotting. This protein, named Gli521, is composed of 4,738 amino acids, has a predicted molecular mass of 520,559 Da, and is coded downstream of a gene for another gliding protein, Gli349, which is known to be responsible for glass binding during gliding. Edman degradation analysis indicated that the N-terminal region is processed at the peptide bond between the amino acid residues at positions 43 and 44. Analysis of gliding mutants isolated previously revealed that the Gli521 protein is missing in a nonbinding mutant, m9, where the gli521 gene is truncated by a nonsense mutation at the codon for the amino acid at position 1170. Immunofluorescence and immunoelectron microscopy indicated that Gli521 localizes all around the base of the membrane protrusion, at the “neck,” as previously observed for Gli349. Analysis of the inhibitory effects of the anti-Gli521 antibody on gliding motility revealed that this protein is responsible for force generation or force transmission, a role distinct from that of Gli349, and also suggested conformational changes of Gli349 and Gli521 during gliding.
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Miyata, M., William S. Ryu, and Howard C. Berg. "Force-velocity relationship of mycoplasma gliding." Seibutsu Butsuri 41, supplement (2001): S203. http://dx.doi.org/10.2142/biophys.41.s203_2.
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Kawanishi, Kengo, Daisuke Fukuda, Hiroyuki Niwa, Taisuke Okuno, Toshinori Miyashita, Takashi Kitagawa, and Shintarou Kudo. "Relationship between Tissue Gliding of the Lateral Thigh and Gait Parameters after Trochanteric Fractures." Sensors 22, no. 10 (May 19, 2022): 3842. http://dx.doi.org/10.3390/s22103842.
Повний текст джерелаАнотація:
Trochanteric fractures lead to severe functional deficits and gait disorders compared to femoral neck fractures. This study aims to investigate gait parameters related to gliding between tissues (gliding) after trochanteric fracture (TF) surgery. This study implemented a cross-sectional design and was conducted amongst patients who underwent TF surgery (n = 94) approximately three weeks post-trochanteric fracture surgery. The following parameters were evaluated: (1) gliding between tissues; (2) lateral femoral pain during loading; (3) maximum gait speed; (4) stride time variability and step time asymmetry as measures of gait cycle variability; (5) double stance ratio and single stance ratio for assessment of stance phase, (6) jerk; and (7) Locomotor rehabilitation index as a measure of force changes during gait. The gliding coefficient was significantly correlated with lateral femoral pain (r = 0.517), jerk root mean square (r = −0.433), and initial contact-loading response jerk (r = −0.459). The jerk of the force change value during gait was also effective in understanding the characteristics of the gait in the initial contact-loading response in patients with trochanteric fractures. Additionally, gliding is related not only to impairments such as pain but also to disabilities such as those affecting gait.
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Fu, S. C., L. K. Hung, Y. W. Lee, T. Y. Mok, and K. M. Chan. "Tendon adhesion measured by a video-assisted gliding test in a chicken model." Journal of Hand Surgery (European Volume) 36, no. 1 (September 3, 2010): 40–47. http://dx.doi.org/10.1177/1753193410381674.
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We developed a video-assisted gliding test to evaluate the gliding force and the flexion angle with unrestricted joint motion. Tendon adhesion was induced in a chicken model of flexor digitorum profundus (FDP) injury at the annular pulley region of the long toe. The chicken feet were harvested immediately after injury, and 2 weeks and 6 weeks after injury. During the gliding test, the injured FDP was pulled for 15 mm then returned to its initial position. The test was recorded using a video camera and registered to the gliding test mechanical data. The maximum flexion angle and gliding resistance were calculated. The maximum flexion angle was significantly decreased from 78 (SD 10) in controls to 42 (SD 22) in tendons with injury, while gliding resistance was significantly increased in week 2 (0.06, SD 0.05) and week 6 (0.07, SD 0.01) after injury.
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Carmigniani, R., L. Seifert, D. Chollet, and C. Clanet. "Coordination changes in front-crawl swimming." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2237 (May 2020): 20200071. http://dx.doi.org/10.1098/rspa.2020.0071.
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We report the evolution of the coordination with velocity in front-crawl swimming which is used in competitions over a large range of distances (from 50 m up to 25 km in open-water races). Inside this single stroke, top-level swimmers show different patterns of arm organization. At low velocities, swimmers select an alternated stroke with gliding pauses during their propulsion. The relative duration of the gliding pauses on a stroke cycle is independent of the velocity in this first regime. Above a critical velocity, the relative duration of the gliding pauses starts to decrease as speed increases. Above a second critical velocity, the gliding pauses disappear and the swimmers start to superpose their propulsion phases. These three regimes are first revealed experimentally and then studied theoretically. It appears that below the first critical velocity, swimmers use a constant coordination index and vary their speed by varying their propulsive force to minimize their cost of propulsion. For larger velocities, swimmers use their maximum propulsive force and vary their recovery time to increase further their speed. The physical model developed is general and could be applied to understand other modes of locomotion.
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Mizutani, Masaki, Isil Tulum, Yoshiaki Kinosita, Takayuki Nishizaka, and Makoto Miyata. "Detailed Analyses of Stall Force Generation in Mycoplasma mobile Gliding." Biophysical Journal 114, no. 6 (March 2018): 1411–19. http://dx.doi.org/10.1016/j.bpj.2018.01.029.
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Wong, Yoke-Rung, Ita Suzana Mat Jais, Min-Kai Chang, Beng-Hai Lim, and Shian-Chao Tay. "An Exploratory Study Using Semi-Tabular Plate in Zone II Flexor Tendon Repair." Journal of Hand Surgery (Asian-Pacific Volume) 23, no. 04 (November 15, 2018): 547–53. http://dx.doi.org/10.1142/s242483551850056x.
Повний текст джерелаАнотація:
Background: This study evaluated the feasibility of using a low-profile titanium (Ti) plate implant, also known as the Ti-button, for Zone II flexor tendon repair. We hypothesize that the use of the Ti-button can distribute the tensile force on the digital flexor tendons to achieve better biomechanical performance. Methods: Twenty lacerated porcine flexor tendons were randomly divided into two groups and repaired using Ti-button or 6-strand modified Lim-Tsai technique. Ultimate tensile strength, load to 2 mm gap force, and mode of failure were recorded during a single cycle loading test. We also harvested twelve fingers with lacerated flexor digitorum profundus tendons from six fresh-frozen cadaver hands and repaired the tendons using either Ti-button method or modified Lim-Tsai technique. A custom-made bio-friction measurement jig was used to measure the gliding resistance and coefficient of friction of the tendon sheath interface at the A2 pulley. Results: The ultimate tensile strength, load to 2 mm gap force, stiffness, and gliding resistance of the Ti-button repairs were 101.5 N, 25.7 N, 7.8 N/mm, and 2.2 N respectively. Ti-button repairs had significantly higher ultimate tensile strength and stiffness than the modified Lim-Tsai repair. However, Ti-button also increased the gliding resistance and coefficient of friction but there was no significant difference between the two repair techniques. Conclusions: Ti-button repair displayed comparable mechanical properties to the traditional repair in terms of 2-mm gap formation and gliding resistance, but with a stronger repair construct. Thus, this deepened our interest to further investigate the potential of using Ti-button implant in Zone II flexor tendon repair by studying both the mechanical and biochemical (tendon healing) properties in more in-depth.
Дисертації з теми "Gliding force"
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Haguet, Julie. "Gliding of a way soft elastomer on a lubricated hard glass surface." Grenoble INPG, 2010. http://www.theses.fr/2010INPG0162.
Повний текст джерелаАнотація:
Les matériaux constitutifs des seringues destinées à l'industrie pharmaceutique peuvent entraîner des interactions indésirables avec les solutions médicamenteuses qu'elles contiennent. Lors du glissement d'un joint de piston dans le corps d'une seringue, les matériaux utilisés, la géométrie des différents éléments ainsi que les conditions expérimentales déterminent la mécanique du glissement. L'étude du glissement d'un joint de piston en élastomère mou dans un corps de seringue en verre lubrifié a été réalisée. L'influence de différents paramètres sur les forces de frottement tels que la viscosité et la quantité du lubrifiant et la nature de l'élastomère, a été étudiée. Cette étude couplée à une modélisation a permis de mettre en évidence des paramètres clés qui gouvernent la forme générale d'une courbe de glissement tels que la déformation du joint de piston et le cisaillement de l'huile. De plus, la condition nécessaire pour obtenir un pic d'activation sur les courbes de glissement est d'avoir une variation du coefficient de frottement qui suit une courbe de StribeckPrefillable syringes for the pharmaceutical industry are made of different kinds of materials which can have undesirable interactions with the medicinal solutions present inside the syringe barrel. When a plunger stopper glides inside a syringe barrel, the materials used and the geometry of the different elements influence the gliding mechanics. The study of the gliding of a wavy elastomeric plunger stopper inside a siliconized glass barrel has been done. The influence of various parameters on the gliding forces, as the viscosity and the quantity of the lubricant, and the nature of the elastomer has been studied. This experimental study has been coupled to a modelization which has enabled to emphasize some critical parameters that govern the general shape of a gliding curve as the deformation of the stopper and the shear of the silicone oil. A necessary condition to obtain an activation peak for the gliding curves is to have a friction coefficient that follows a Stribeck-like variation
Книги з теми "Gliding force"
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Gliding for gold: The physics of winter sports. Baltimore: Johns Hopkins University Press, 2011.
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Durbeck, Virginia Paxton. Gliding forward, glancing back: Journal of an Air Force wife, 1921-1968. Baltimore: Gateway Press, 1999.
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Biewener, Andrew A., and Shelia N. Patek, eds. Movement in Air. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198743156.003.0006.
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Aerial flight involves the same fluid mechanical principles as aquatic locomotion. However, the 800-fold lower density of air compared with water has marked consequences on the mechanisms of aerial locomotion. We examine the forces acting on a flying animal in which these fluid forces can be calculated. We then consider how basic features of the wings and body affect flight forces. Building on this understanding, we examine the power requirements associated with flight as a function of flight speed, based on conventional aerodynamics (i.e. steady airflow past non-oscillating wings, which applies to most engineered aircraft). Gliding flight is explained by steady-state theory and is discussed in this context. However, because flying animals must flap their wings to support weight and overcome drag, non-steady aerodynamic effects come into play. These non-steady aerodynamic effects are revealed by tracking the flow over a moving wing or by the use of robotic models.
Частини книг з теми "Gliding force"
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Koch, Arthur L. "Gliding Motility, Protonmotive Force, and Flagellar Rotation." In Bacterial Growth and Form, 361–77. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1779-5_14.
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Koch, Arthur L. "Gliding Motility, Protonmotive Force Motor, and Flagellar Rotation." In Bacterial Growth and Form, 391–408. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-017-0827-2_15.
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Paschal, Bryce M., and Richard B. Vallee. "Chapter 4 Microtubule and Axoneme Gliding Assays for Force Production by Microtubule Motor Proteins." In Methods in Cell Biology, 65–74. Elsevier, 1993. http://dx.doi.org/10.1016/s0091-679x(08)60161-2.
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Senekovic, Vladimir. "Subacromial InSpace Balloon Interposition for Massive Irreparable Rotator Cuff Tears." In Shoulder Surgery for RC Pathology, Arthropathy and Tumors [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102558.
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Massive rotator cuff tears are a challenging problem for treatment. The best results we can still achieve with reconstruction. For treatment of massive rotator cuff tears when reconstruction is not possible, a new method has been developed recently: the implantation of the biodegradable balloon spacer/InSpace™ balloon/filled with the saline in the subacromial space. The main characteristic of this method is that to allow gliding of the humeral head against acromion without friction and to depress the humeral head for 2–3 mm. This depression is just enough that the humerus is in a better center of rotation that allows the deltoid muscle more strength—better vector forces for the deltoid muscle. This function of the balloon permits better deltoid activation and compensation through the arc of motion. Results of our first study and results of others show clinical safety and efficacy of the insertion of the InSpace™ balloon in a group of patients with massive irreparable rotator cuff tears. The insertion of this device shows significantly better early improvement, significant improvement in subjective pain scores, and a decrease in reported night pain. The measurement of the Total Constant score showed statistically significant improvement after insertion of the InSpace™ balloon at 5 years of follow-up. Generally, all studies show 75–80% of good results.
Тези доповідей конференцій з теми "Gliding force"
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Nitta, Takahiro, and Kouki Kawauchi. "Gliding Movements of Microtubule Driven by Kinesin Motors under External Force: Steering and Detachment." In 9th EAI International Conference on Bio-inspired Information and Communications Technologies (formerly BIONETICS). ACM, 2016. http://dx.doi.org/10.4108/eai.3-12-2015.2262537.
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Peña, Edward, David E. Thompson, and Roslyn B. Evans. "Tendon Force Estimates Following Hand Surgery." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0333.
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Abstract The need for quantitative methods for assessment of tendon forces following tendon reconstructive surgery arises because of the side effects of current post-operative therapy. The classical therapy over the past 50 years has been to insulate the hand from potential injury in a cradle of bandages. This method was originally introduced because movement of the hand following surgery was felt to result in failures of the repaired tendons which have a very limited strength. The subsequent stiffening of the joints, and reduction in the gliding action of tendons is exacerbated by the swelling and inflammatory processes resulting from the surgery. In recent years, a new post-surgical therapy has been introduced that dramatically improves the range of motion and reduces the time to clinical release of the patient. This procedure is similar to that used prior to the current conservative therapy, but better analytical methods have allowed restrictions to be imposed on the active motion of the hand following surgery. The force analysis that has led to new guidelines for post-surgical hand therapy for flexor tendons is presented here. A graphical user interface is also presented which allows the user to study various external force loadings and obtain rapid feedback on the resulting tendon forces at user-defined joint angles. This is shown in Figure 1.
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Park, Eun-Jung, Myoung-Ock Cho, and Jung Kyung Kim. "Growth Responses of Swarming and Gliding Bacteria on Substrates With Different Levels of Stiffness." In ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13154.
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We conducted experiments to decipher the interplays among bacterial motility, surface stiffness of culture medium, and growth of colony when bacteria grow on semi-solid substrate. We observed the growth kinetics of two kinds of bacteria, swarming Escherichia coli (E.coli) and gliding Myxococcus Xanthus (M.xanthus), grown on semi-solid agar substrates with different stiffness. The colony of M.xanthus moved by traction force on the surface shows a tendency to grow larger on soft substrate. The colony of E.coli using flagella shows a similar tendency in the early phase but later grows smaller on substrate with lower stiffness. We found that the growth of bacterial colony is affected by the mechanical properties of the substrate and the type of bacterial motility as well.
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Bandyopadhyay, Promode R. "Flying Fish Sculls to Taxi and Perturbs Wing Lift With Travelling Waves to Land." In ASME 2016 Fluids Engineering Division Summer Meeting collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fedsm2016-7507.
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The top 200 meters of oceans abound in life forms since photosynthesis is possible in that layer. Competition and predator-prey (swordfish-flying fish, 102–104 to 1 mass ratio) interactions are intense here. Chased by predators, a flying fish (FF) — a pleuston — frantically escapes from the water and becomes airborne. Here we report the visual observations of oceanic surface and body distortions of FF to surmise the mechanisms of propulsion during taxiing and landing. FF leaps, not when it is chased, but when the additional energy required for further increase in speed underwater exceeds that required to leap.1 The higher metabolic cost of transport of regular flapping flight in air than in water is circumvented by gliding. We examine the BBCTV video2 by Richard Attenborough, the noted naturalist. An FF may camber its wings like parafoils and may also twist the outer half of the wings during taxiing and climbing. To produce thrust during taxiing, the FF sculls with the lower lobe of the tail fin to produce a reverse Karman vortex jet; there is rapid flicking of the lower lobe of the tail fin tangentially over the surface. The body acts as a chaotic damped and driven pendulum to produce the high-velocity wide flick. To damp after takeoff, it becomes a single asymmetric pendulum. Unpowered (foil) gliding follows. For descent, the wings are shaped, untwisted parafoils and, just prior to touchdown, travelling waves are superimposed, producing, in contrast to taxiing, an impressively smooth small-angle-of-attack tail touchdown on water without any nose-down. The spiked crowns of Richtmyer-Meshkov interface instability are visible on the ocean surface during leaping but not during landing. Trailing hydraulic jumps are observable during landing but not during leaping. The leap is a high-acceleration and Weber number dominated (inertia/capillary forces) phenomenon, but the landing involves little impact force and is dominated by Froude number forces (inertia/gravity forces). The evidence suggests that, prior to leaping and while still underwater, the FF reads the surface wind direction to align the flight path.
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Galvin, Samson, Rachael Yanalitis, Joshua Winder, Randy Haluck, Paris von Lockette, and Jason Moore. "Selection of Low Friction Material for Novel Single Incision, Free Motion Laparoscopic Surgical System." In 2022 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/dmd2022-1021.
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Abstract Laparoscopic surgery is a common minimally invasive procedure typically used in intestinal surgery. Several small incisions are made to allow specialized instruments to be inserted and operated in an inflated abdomen. There is limited mobility in these procedures and additional training must be completed for surgeons to become proficient. To increase the freedom of motion and reduce the required skill for the surgeon, the novel single incision, free motion (SIFM) laparoscopic surgical system is introduced. This device will allow for free motion of the tools with a single incision inside the body, using electromagnets, hydraulic, and motor actuation. Using a low friction material, an electromagnet on the outside of the skin translates the tool inside the body. Hydraulic and motor actuation allows for further control of the tool under the skin by tilting, extending and retraction. Experimentation was performed to measure the frictional forces of different materials gliding over porcine skin tissue. The results show that of the tested materials, Teflon performed the best with high consistency and low coefficients of friction across a range of pressures. Future work will explore magnetic force and actuation to work with the low friction materials of SIFM.
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Fernandez, Rajan, and Keith Alexander. "An Experimental Investigation Assessing the Validity of Quasi-Static Calculations for an Oscillating Hydrofoil." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49440.
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Inspired by animals, flapping wing propulsion has been of interest since the early 1900s. Flapping hydrofoil propulsion has been attempted by designers of human powered watercraft because of the novelty and the apparent high theoretical efficiency, but with limited success. The earliest human powered hydrofoil, the Wasserlaufer, was invented by Julius Schuck in 1953. The first really successful human powered hydrofoil, the Trampofoil, was invented by Alexander Sahlin in 1998. While these craft function adequately the design data for flapping hydrofoils is inadequate or not available. This paper describes an experimental program and initial results for the required data. To design a vehicle with a lifting and thrusting oscillating hydrofoil the force that the hydrofoil will exert on the vehicle through its entire oscillating cycle must ideally be known. The force profiles could be estimated via quasi-static calculations based on steady flow lift and drag coefficients, but these often do not cover the full 360 degree range that can be required and there is doubt that the steady flow coefficients properly represent the dynamic situation of an oscillating hydrofoil. Hence a valuable process would be one that could determine dynamic drag and lift coefficient loops as function of the Strouhal number, heaving and pitching profiles. To work toward the collection of this information, experimental data is being recorded in a towing tank with an oscillating NACA4415 hydrofoil over a range of Strouhal numbers and types of oscillating profiles. While there are still some limitations to the experimental equipment preliminary experimental results show the limitations of using quasi-static calculations and go some way to providing the design data for the hydrofoil section tested. We conclude that quasi-static calculations based on the gliding coefficient curve for for an oscillating hydrofoil are only valid for very small Strouhal numbers (St≪0.05). We have shown that as the Strouhal number increases, the error in such calculations increases very rapidly. We also note that the lift coefficient of the hydrofoil has a strong dependence on the angle of attack and is not affected by the gliding stall.
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Zhou, Wei, Yinong Chen, Yijun Ma, and Xu Pei. "Attitude Adjustment of a Quadruped Robot in the Air." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-47348.
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When the moments of climbing robots, jumping robots, and gliding robots extend to the air, they should reorient themselves to minimize the damage during a fall. Based on imitating a falling cat, robot can reorientate about one axis without external force. In this paper, an extended attitude adjustment method for quadruped robots is presented to achieve three degrees of freedom attitude adjustment with the movement of four robotic limbs. A mathematical model of a falling robot is established based on the multi-rigid-body unrooted tree system. The response of the prototype’s azimuth to the input of the cylindrical hinges is analyzed. A 3D model prototype was designed in SolidWorks and simulation experiments were carried out in ADAMS. Prototype were manufactured with a 3D printer, to validate the attitude adjustment method. The simulation and experimental results showed that the main body of the prototype was able to rotate respectively 89 degrees in the X-axis, 89 degrees in Y-axis, and 49 degrees in Z-axis in a movement cycle of the robotic limbs.
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Gao, Lei, Ran He, Yangge Li, and Zhiguo Zhang. "Analysis of Autonomous Underwater Gliders Motion for Ocean Research." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24534.
Повний текст джерелаАнотація:
Underwater gliders, a type of highly efficient underwater vehicle which uses gravity and buoyancy for propulsion, has been studied for a long time during the last 3 decades. This paper describes the development of the principle dynamic models of a general underwater glider, including hydrodynamic forces and buoyancy effects. The numerical analysis model was developed for the underwater glider motion. Dynamic forces equations including the model’s buoyancy, gravity, and hydrodynamic forces in gliding are derived. Gliding velocities with changes of the net buoyancy are compared. The numerical method was used to calculate the hydrodynamics coefficient of the glider. Dynamic characteristics of the Seaglider and SLOCUM have been used as validation objects for the numerical method. The glide angle is merely the function of the lift/drag ratio and has no relation to the net buoyancy. The gliding velocity would increase when the buoyancy increases.
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Dohnal, Fadi, Wolfgang Paradeiser, and Horst Ecker. "Experimental Study on Cancelling Self-Excited Vibrations by Parametric Excitation." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14552.
Повний текст джерелаАнотація:
This article reports on the experimental verification of an anti-resonance effect obtained by parametric stiffness excitation. From theoretical studies it is known that parametric excitation at non-resonant parametric resonances can improve the damping behavior of a mechanical system and even stabilize an otherwise unstable system. To demonstrate this effect, a test setup was designed, based on a two-mass vibration system, gliding on an air track. Parametric stiffness excitation (PSE) was realized by a mechanical device that creates a time-periodic stiffness by modulating the tension in an elastic rubber band. With this device it was possible to demonstrate the improved damping behavior of the system when the PSE device is operating at or near the first parametric combination resonance of difference type. Also, a simple electro-magnetic device was used to create self-exciting forces. It could be shown for the first time that it is indeed possible to stabilize the unstable system by introducing parametric stiffness excitation.
Звіти організацій з теми "Gliding force"
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Epel, Bernard, and Roger Beachy. Mechanisms of intra- and intercellular targeting and movement of tobacco mosaic virus. United States Department of Agriculture, November 2005. http://dx.doi.org/10.32747/2005.7695874.bard.
Повний текст джерелаАнотація:
To cause disease, plant viruses must replicate and spread locally and systemically within the host. Cell-to-cell virus spread is mediated by virus-encoded movement proteins (MPs), which modify the structure and function of plasmodesmata (Pd), trans-wall co-axial membranous tunnels that interconnect the cytoplasm of neighboring cells. Tobacco mosaic virus (TMV) employ a single MP for cell- cell spread and for which CP is not required. The PIs, Beachy (USA) and Epel (Israel) and co-workers, developed new tools and approaches for study of the mechanism of spread of TMV that lead to a partial identification and molecular characterization of the cellular machinery involved in the trafficking process. Original research objectives: Based on our data and those of others, we proposed a working model of plant viral spread. Our model stated that MPᵀᴹⱽ, an integral ER membrane protein with its C-terminus exposed to the cytoplasm (Reichel and Beachy, 1998), alters the Pd SEL, causes the Pd cytoplasmic annulus to dilate (Wolf et al., 1989), allowing ER to glide through Pd and that this gliding is cytoskeleton mediated. The model claimed that in absence of MP, the ER in Pd (the desmotubule) is stationary, i.e. does not move through the Pd. Based on this model we designed a series of experiments to test the following questions: -Does MP potentiate ER movement through the Pd? - In the presence of MP, is there communication between adjacent cells via ER lumen? -Does MP potentiate the movement of cytoskeletal elements cell to cell? -Is MP required for cell-to-cell movement of ER membranes between cells in sink tissue? -Is the binding in situ of MP to RNA specific to vRNA sequences or is it nonspecific as measured in vitro? And if specific: -What sequences of RNA are involved in binding to MP? And finally, what host proteins are associated with MP during intracellular targeting to various subcellular targets and what if any post-translational modifications occur to MP, other than phosphorylation (Kawakami et al., 1999)? Major conclusions, solutions and achievements. A new quantitative tool was developed to measure the "coefficient of conductivity" of Pd to cytoplasmic soluble proteins. Employing this tool, we measured changes in Pd conductivity in epidermal cells of sink and source leaves of wild-type and transgenic Nicotiana benthamiana (N. benthamiana) plants expressing MPᵀᴹⱽ incubated both in dark and light and at 16 and 25 ᵒC (Liarzi and Epel, 2005 (appendix 1). To test our model we measured the effect of the presence of MP on cell-to-cell spread of a cytoplasmic fluorescent probe, of two ER intrinsic membrane protein-probes and two ER lumen protein-probes fused to GFP. The effect of a mutant virus that is incapable of cell-to-cell spread on the spread of these probes was also determined. Our data shows that MP reduces SEL for cytoplasmic molecules, dilates the desmotubule allowing cell-cell diffusion of proteins via the desmotubule lumen and reduces the rate of spread of the ER membrane probes. Replicase was shown to enhance cell-cell spread. The data are not in support of the proposed model and have led us to propose a new model for virus cell-cell spread: this model proposes that MP, an integral ER membrane protein, forms a MP:vRNAER complex and that this ER-membrane complex diffuses in the lipid milieu of the ER into the desmotubule (the ER within the Pd), and spreads cell to cell by simple diffusion in the ER/desmotubule membrane; the driving force for spread is the chemical potential gradient between an infected cell and contingent non-infected neighbors. Our data also suggests that the virus replicase has a function in altering the Pd conductivity. Transgenic plant lines that express the MP gene of the Cg tobamovirus fused to YFP under the control the ecdysone receptor and methoxyfenocide ligand were generated by the Beachy group and the expression pattern and the timing and targeting patterns were determined. A vector expressing this MPs was also developed for use by the Epel lab . The transgenic lines are being used to identify and isolate host genes that are required for cell-to-cell movement of TMV/tobamoviruses. This line is now being grown and to be employed in proteomic studies which will commence November 2005. T-DNA insertion mutagenesis is being developed to identify and isolate host genes required for cell-to-cell movement of TMV.