scholarly journals Jumping without slipping: leafhoppers (Hemiptera: Cicadellidae) possess special tarsal structures for jumping from smooth surfaces

2017 ◽  
Vol 14 (130) ◽  
pp. 20170022 ◽  
Author(s):  
Christofer J. Clemente ◽  
Hanns Hagen Goetzke ◽  
James M. R. Bullock ◽  
Gregory P. Sutton ◽  
Malcolm Burrows ◽  
...  
Keyword(s):  
High Speed ◽  
Smooth Surfaces ◽  
Velocity Dependence ◽  
Force Measurements ◽  
Acceleration Phase ◽  
Friction Forces ◽  
Anisotropic Friction ◽  
Rapid Control ◽  
Pulling Forces ◽  
Pushing And Pulling

Many hemipteran bugs can jump explosively from plant substrates, which can be very smooth. We therefore analysed the jumping performance of froghoppers ( Philaenus spumarius, Aphrophoridae) and leafhoppers ( Aphrodes bicinctus/makarovi, Cicadellidae) taking off from smooth (glass) and rough (sandpaper, 30 µm asperity size) surfaces. On glass, the propulsive hind legs of Philaenus froghoppers slipped, resulting in uncontrolled jumps with a fast forward spin, a steeper angle and only a quarter of the velocity compared with jumps from rough surfaces. By contrast, Aphrodes leafhoppers took off without their propulsive hind legs slipping, and reached low take-off angles and high velocities on both substrates. This difference in jumping ability from smooth surfaces can be explained not only by the lower acceleration of the long-legged leafhoppers, but also by the presence of 2–9 soft pad-like structures (platellae) on their hind tarsi, which are absent in froghoppers. High-speed videos of jumping showed that platellae contact the surface briefly (approx. 3 ms) during the acceleration phase. Friction force measurements on individual hind tarsi on glass revealed that at low sliding speeds, both pushing and pulling forces were small, and insufficient to explain the recorded jumps. Only when the tarsi were pushed with higher velocities did the contact area of the platellae increase markedly, and high friction forces were produced, consistent with the observed jumps. Our findings show that leafhoppers have special adhesive footpads for jumping from smooth surfaces, which achieve firm grip and rapid control of attachment/detachment by combining anisotropic friction with velocity dependence.

Experimental Study of a Variable Pressure Damper on Automotive Valve Motion

1996 ◽  
Author(s):  
Jin-Jang Liou ◽  
Grodrue Huang ◽  
Wensyang Hsu
Keyword(s):  
Experimental Study ◽  
Friction Coefficient ◽  
Friction Force ◽  
High Speed ◽  
Experimental Results ◽  
Variable Pressure ◽  
Friction Forces ◽  
Valve Spring ◽  
Valve Motion

Abstract A variable pressure damper (VPD) is used here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve bouncing phenomenon. The friction force on the valve spring is found experimentally, and the corresponding friction coefficient is also determined. Dynamic valve displacements at different speeds with different friction forces are calibrated. Bouncing and floating of the valve are observed when the camshaft reaches high speed. From the measured valve displacement, the VPD is shown to have significant improvement in reducing valve bouncing distance and eliminating floating. However, experimental results indicate that the valve bouncing can not be eliminated completely when the camshaft speed is at 2985 rpm.

The kinematics and mechanism of prey capture in the African pig-nosed frog (Hemisus marmoratum): description of a radically divergent anuran tongue.

1995 ◽  
Vol 198 (9) ◽  
pp. 2025-2040 ◽  
Author(s):  
D Ritter ◽  
K Nishikawa
Keyword(s):  
Feeding Behavior ◽  
Strong Evidence ◽  
Muscle Function ◽  
High Speed ◽  
Prey Capture ◽  
Three Dimensions ◽  
Muscle Denervation ◽  
Genioglossus Muscle ◽  
Pulling Forces ◽  
Hydraulic Mechanism

High-speed videography and muscle denervation experiments were used to quantify the feeding kinematics of Hemisus marmoratum and to test hypotheses of muscle function. The feeding behavior of H. marmoratum, which feeds on ants and termites, differs radically from that of other frogs that have been studied. During feeding in H. marmoratum, the tongue 'telescopes' straight out of the mouth, as opposed to the 'flipping' tongue trajectory observed in most other frogs. At the time of prey contact, two lateral lobes of tissue at the tongue tip envelop the prey. These lateral lobes are capable of applying significant pulling forces to the prey and the tongue is, therefore, described as prehensile. The trajectory of the tongue can be adjusted throughout protraction so that the frog can 'aim' its tongue in all three dimensions; distance, azimuth and elevation. Bilateral denervation of the genioglossus muscles results in a complete lack of tongue protraction, indicating that the genioglossus muscle is the main tongue protractor in H. marmoratum, as in other frogs. Thus, H. marmoratum provides strong evidence of functional conservatism of the genioglossus muscle within anurans. Bilateral denervation of the hyoglossus muscle indicates that although the hyoglossus is involved in several aspects of normal tongue retraction, including the prehensile capability of the tongue tip, it is not necessary for tongue retraction. Unilateral denervation of the genioglossus muscle causes significant deviation of the tongue towards the denervated side, providing evidence for a mechanism of lateral tongue aiming. On the basis of the kinematics of prey capture, the anatomy of the tongue and the results of the denervation experiments, we propose that H. marmoratum uses a hydraulic mechanism to protract its tongue.

Friction Force Measurements Using the Instantaneous IMEP Method and Comparison With RINGPAK Simulations

2005 ◽  
Author(s):  
Myoungjin Kim ◽  
Thomas M. Kiehne ◽  
Ronald D. Matthews
Keyword(s):  
Friction Force ◽  
Piston Ring ◽  
Cost Effective ◽  
Firing Condition ◽  
Force Measurements ◽  
Connecting Rod ◽  
Friction Forces ◽  
Bench Tests ◽  
Ring Assembly ◽  
Analysis System

Even though many researchers have measured the piston/ring assembly friction force over the last several decades, accurate measurement of the piston/ring assembly friction force is a still challenging problem. The floating liner method is not widely used, in spite of its accuracy, due to the substantial modifications required to the engine. On the other extreme, bench tests of the piston/ring assembly cannot completely simulate the real firing condition although bench tests are rapid, consistent, and cost effective. In this study, friction forces of the piston/ring assembly were measured using the instantaneous IMEP method and compared with modeling results using Ricardo’s RINGPAK software. In this research, a flexible flat cable was used to connect the connecting rod strain gage signal to the analysis system instead of using a grasshopper linkage. Therefore, the piston/ring assembly friction force was measured with the minimum change to the engine hardware.

scholarly journals Traction force measurements on male Strepsiptera (Insecta) revealed higher forces on smooth compared with hairy substrates

2020 ◽  
Vol 223 (18) ◽  
pp. jeb223784
Author(s):  
Hans Pohl ◽  
Elena V. Gorb ◽  
Stanislav N. Gorb
Keyword(s):  
Van Der Waals ◽  
Traction Force ◽  
Capillary Forces ◽  
Van Der Waals Interactions ◽  
Smooth Surfaces ◽  
Mechanical Interlocking ◽  
Force Measurements ◽  
Caudal Direction ◽  
Primary Contribution

ABSTRACTThe aim of this study was to find out how strongly the parasitic insect Stylopsovinae, which has tarsi equipped with tenent hairs and lacking claws, attaches to different substrates. We investigated adhesion of male S. ovinae to the abdomen of its hymenopteran host (Andrena vaga), the hairier abdomen of a Bombus sp. and two artificial smooth reference surfaces with different degrees of hydrophilicity. In our experiments, the male S. ovinae developed significantly higher forces on smooth surfaces. However, the forces were significantly lower on all the hymenopteran surfaces used in the experiment. The absence of anisotropy in the force grip in cranial/caudal direction relative to the host might indirectly indicate that S. ovinae generate forces by adhesion rather than mechanical interlocking with the host hairs. The tolerance of the attachment system of S. ovinae to the substrate chemistry might be explained by the primary contribution of van der Waals interactions and not capillary forces to adhesion in S. ovinae.

scholarly journals Froghoppers jump from smooth plant surfaces by piercing them with sharp spines

2019 ◽  
Vol 116 (8) ◽  
pp. 3012-3017 ◽  
Author(s):  
Hanns Hagen Goetzke ◽  
Jonathan G. Pattrick ◽  
Walter Federle
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
High Speed ◽  
Blue Staining ◽  
Acceleration Phase ◽  
Synthetic Adhesives ◽  
3D Environments ◽  
Attachment Mechanism ◽  
Plant Surfaces ◽  
Scanning Electron

Attachment mechanisms used by climbing animals facilitate their interactions with complex 3D environments and have inspired novel types of synthetic adhesives. Here we investigate one of the most dynamic forms of attachment, used by jumping insects living on plants. Froghopper insects can perform explosive jumps with some of the highest accelerations known among animals. As many plant surfaces are smooth, we studied whether Philaenus spumarius froghoppers are able to take off from such substrates. When attempting to jump from smooth glass, the insects’ hind legs slipped, resulting in weak, uncontrolled jumps with a rapid forward spin. By contrast, on smooth ivy leaves and smooth epoxy surfaces, Philaenus froghoppers performed strong jumps without any slipping. We discovered that the insects produced traction during the acceleration phase by piercing these substrates with sharp spines of their tibia and tarsus. High-speed microscopy recordings of hind legs during the acceleration phase of jumps revealed that the spine tips indented and plastically deformed the substrate. On ivy leaves, the spines of jumping froghoppers perforated the cuticle and epidermal cell walls, and wounds could be visualized after the jumps by methylene blue staining and scanning electron microscopy. Improving attachment performance by indenting or piercing plant surfaces with sharp spines may represent a widespread but previously unrecognized strategy utilized by plant-living insects. This attachment mechanism may also provide inspiration for the design of robotic grippers.

Analysis of Tapered Roller Bearings Considering High Speed and Combined Loading

1976 ◽  
Vol 98 (4) ◽  
pp. 564-572 ◽  
Author(s):  
J. Y. Liu
Keyword(s):  
High Speed ◽  
Analytical Study ◽  
Roller Bearing ◽  
Combined Loading ◽  
Sliding Velocity ◽  
Friction Forces ◽  
Tapered Roller Bearing ◽  
Rolling Contacts ◽  
Tapered Roller ◽  
Tapered Roller Bearings

This paper presents an analytical study of the load distribution in a tapered roller bearing operating at a high speed and under combined loading. The friction forces at the rolling contacts and the cage forces are not considered. A numerical example showing, among other things, the effects of misalignment and speed on the bearing fatigue life and the sliding velocity at the flange contact is given.

scholarly journals Positioning of microtubule organizing centers by cortical pushing and pulling forces

2012 ◽  
Vol 14 (10) ◽  
pp. 105025 ◽  
Author(s):  
Nenad Pavin ◽  
Liedewij Laan ◽  
Rui Ma ◽  
Marileen Dogterom ◽  
Frank Jülicher
Keyword(s):  
Microtubule Organizing Centers ◽  
Pulling Forces ◽  
Pushing And Pulling

scholarly journals Functional morphology of suction discs and attachment performance of the Mediterranean medicinal leech ( Hirudo verbana Carena)

2016 ◽  
Vol 13 (117) ◽  
pp. 20160096 ◽  
Author(s):  
Tim Kampowski ◽  
Laura Eberhard ◽  
Friederike Gallenmüller ◽  
Thomas Speck ◽  
Simon Poppinga
Keyword(s):  
Functional Morphology ◽  
High Speed ◽  
Substrate Surface ◽  
Surrounding Medium ◽  
Medicinal Leech ◽  
Force Measurements ◽  
High Speed Video ◽  
Hirudo Verbana ◽  
Substrate Surface Roughness ◽  
Medicinal Leeches

Medicinal leeches use their suction discs for locomotion, adhesion to the host and, in the case of the anterior disc, also for blood ingestion. The biomechanics of their suction-based adhesion systems has been little understood until now. We investigated the functional morphology of the anterior and posterior suckers of Hirudo verbana by using light and scanning electron microscopy. Furthermore, we analysed the adhesion qualitatively and quantitatively by conducting behavioural and mechanical experiments. Our high-speed video analyses provide new insights into the attachment and detachment processes and we present a detailed description of the leech locomotion cycle. Pull-off force measurements of the anterior and posterior suction organs on seven different substrates under both aerial and water-submersed conditions reveal a significant influence of the surrounding medium, the substrate surface roughness and the tested organ on attachment forces and tenacities.

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