scholarly journals A study On Support Selection Mechanism In Tendrils of Cayratia Japonica

2021 ◽  
Author(s):  
Kazuya Saito
Keyword(s):  
Motion Tracking ◽  
Contact Point ◽  
Large Diameter ◽  
Negative Association ◽  
Branching Pattern ◽  
Selection Mechanism ◽  
Climbing Plants ◽  
Climbing Plant ◽  
Cayratia Japonica ◽  
Different Diameters

Abstract Organisms make decisions when they perceive cues of varying intensities. In case of climbing plants, the diameter of supports in contact (tree or stem) is an important cue for their growth as plants that coil around a support with large diameter are unable to maintain tensional forces required for continued attachment to the support. The negative association between the diameter and the climbing success has been reported since Darwin published his study on climbing plants. However, it is not known if a climbing plant makes a decision to avoid a support with larger diameter. Here, we tested this possibility by observing the coiling response of tendrils of Cayratia japonica to supports with different diameters. The coiling success of the tendrils was affected by the diameter of the support and the tendril lengths. We described the branching pattern of coiling response and demonstrated that the tendrils change their coiling shape depending on the support diameter and the tendril length. To understand the behavioural rules regulating the branching, we constructed a simple model with two assumptions on the tendril movement, (1) when the tendrils receive a contact stimulus, they begin to coil from around the contact point and (2) there is a minimum coiling angle at which the tendrils coil up, once the tendril starts coiling. Image analysis and 3D motion tracking technique revealed that the movement of the tendrils were consistent with the two assumptions of the model. The results suggested that the tendrils flexibly changed the coiling shapes depending on the support diameter and simple behavioural rules could regulate this diameter-dependent response.

In vitro friction and lubrication of large bearing hip prostheses

2009 ◽  
Vol 224 (7) ◽  
pp. 853-864 ◽  
Author(s):  
S Flanagan ◽  
E Jones ◽  
C Birkinshaw
Keyword(s):  
Large Diameter ◽  
Calf Serum ◽  
Mixed Lubrication ◽  
Joint Stability ◽  
Bovine Calf Serum ◽  
Reinforced Polymer ◽  
Metal On Metal ◽  
Different Diameters ◽  
Friction And Lubrication

New material combinations and designs of artificial hip implants are being introduced in an effort to improve proprioception and functional longevity. Larger joints in particular are being developed to improve joint stability, and it is thought that these larger implants will be more satisfactory for younger and more physically active patients. The study detailed here used a hip friction simulator to assess the friction and lubrication properties of large-diameter hip bearings of metal-on-metal and ceramic-on-reinforced-polymer couplings. Joints of different diameters were evaluated to determine what effect, if any, bearing diameter had on lubrication. In addition, the effects of lubricant type are considered, using carboxymethyl cellulose and bovine calf serum, and the physiological lubricant is shown to be considerably more effective at reducing friction. The frictional studies showed that the metal-on-metal joints worked under a mixed lubrication regime, producing similar friction factor values to each other. The addition of bovine calf serum (BCS) reduced the friction. The ceramic-on-reinforced-polymer samples were shown to operate with high friction factors and mixed lubrication. When tested with BCS, the larger-diameter bearings showed a decrease in friction compared with the smaller-size bearings, and the addition of BCS resulted in an increase in friction, unlike the metal-on-metal system. The study demonstrated that the component's diameter had little or no influence on the lubrication and friction of the large bearing combinations tested.

scholarly journals Comparison of the efficacies of 1.0mm and 1.5mm silicone tubes for the treatment of nasolacrimal duct obstruction

2021 ◽  
Author(s):  
Jutaro Nakamura ◽  
Tomoyuki Kamao ◽  
Arisa Mitani ◽  
Nobuhisa Mizuki ◽  
Atsushi Shiraishi
Keyword(s):  
Large Diameter ◽  
Nasolacrimal Duct ◽  
Nasolacrimal Duct Obstruction ◽  
Duct Obstruction ◽  
Tube Removal ◽  
Restricted Mean Survival Time ◽  
Normal Diameter ◽  
Silicone Tube Intubation ◽  
One Year ◽  
Different Diameters

Abstract This study was designed to compare the postoperative outcomes of bicanalicular intubation using different diameters of silicone tubes to treat post-saccal nasolacrimal duct obstruction. A total of 130 patients diagnosed with post-saccal obstruction who underwent endoscopic-assisted silicone tube intubation were included in the study. The patients were divided into two groups; those intubated with a 1.5-mm large diameter tube (Group LD) and those with a 1.0-mm normal diameter tube (Group ND). The patency rates of the two groups at one year after tube removal were compared using the Kaplan–Meier's curve and Restricted mean survival time (RMST) method with τ = 365 days. Results showed that the recurrence rate after tube removal was significantly lower in the LD group compared to the ND group (p = 0.001). The patency rates at one year after removal in the LD and ND group were 0.857 (0.754-0.919) and 0.739 (0.617-0.828), respectively. When comparing the patency rates by the RMST method at τ = 365 days, the RMST difference, RMST ratio, and RMTL ratio were significantly higher in the LD group at p = 0.045, 0.052, and 0.046, respectively.

scholarly journals Angiosperms, climbing plants in tropical forests of southern Eastern Ghats, Tamil Nadu, India

Check List ◽  
2009 ◽  
Vol 5 (1) ◽  
pp. 092 ◽  
Author(s):  
Chellam Muthumperumal ◽  
Narayanaswamy Parthasarathy
Keyword(s):  
Tropical Forests ◽  
Plant Species ◽  
Tamil Nadu ◽  
Habitat Specialization ◽  
Eastern Ghats ◽  
Check List ◽  
Peninsular India ◽  
Woody Vines ◽  
Climbing Plants ◽  
Climbing Plant

We provide a check list of angiosperm climbing plant species, along with their climbing modes, enumerated from a total of one hundred and fifty grids in tropical forests of southern Eastern Ghats, peninsular India. The Eastern Ghats constitute an important biodiversity area in India and have been studied earlier mainly for the floristics, and that too confined to a few prioritized sites. Lianas, the woody vines contribute substantially to the diversity and structure of most tropical forests. Yet, little is known about the importance of habitat specialization in maintaining tropical liana diversity. A genera and 40 families are included in this enumeration.

scholarly journals Flexible control of movement in plants

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Silvia Guerra ◽  
Alessandro Peressotti ◽  
Francesca Peressotti ◽  
Maria Bulgheroni ◽  
Walter Baccinelli ◽  
...  
Keyword(s):  
Charles Darwin ◽  
Unsolved Problem ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Specific Interest ◽  
Flexible Control ◽  
Climbing Plants ◽  
Climbing Plant ◽  
And Control ◽  
Approach Phase

Abstract Although plants are essentially sessile in nature, these organisms are very much in tune with their environment and are capable of a variety of movements. This may come as a surprise to many non-botanists, but not to Charles Darwin, who reported that plants do produce movements. Following Darwin’s specific interest on climbing plants, this paper will focus on the attachment mechanisms by the tendrils. We draw attention to an unsolved problem in available literature: whether during the approach phase the tendrils of climbing plants consider the structure of the support they intend to grasp and plan the movement accordingly ahead of time. Here we report the first empirical evidence that this might be the case. The three-dimensional (3D) kinematic analysis of a climbing plant (Pisum sativum L.) demonstrates that the plant not only perceives the support, but it scales the kinematics of tendrils’ aperture according to its thickness. When the same support is represented in two-dimensions (2D), and thus unclimbable, there is no evidence for such scaling. In these circumstances the tendrils’ kinematics resemble those observed for the condition in which no support was offered. We discuss these data in light of the evidence suggesting that plants are equipped with sensory mechanisms able to provide the necessary information to plan and control a movement.

Clogging mechanisms of filter barriers against debris-flow hazard

2021 ◽  
Author(s):  
Filippo Mauro ◽  
Alessandro Leonardi ◽  
Marina Pirulli
Keyword(s):  
Debris Flows ◽  
Large Diameter ◽  
Particle Diameter ◽  
Small Diameter ◽  
Equivalent Diameter ◽  
Threshold Values ◽  
Different Diameters ◽  
Debris Flow Hazard ◽  
Key Parameter

<p>Debris flows are amongst the most hazardous landslide phenomena (Jakob & Hungr, 2005). They are mixtures of flowing water and granular materials, which range in size from microscopic soil particles to massive rock boulders. Due to their unpredictability and rapidity, they pose severe hazard on infrastructure, structures, and human lives. To dissipate the destructive kinetic energy of debris flows and induce deposition of the coarsest fraction of the flow, mitigation systems often include the use of filter barriers. Filter barriers are built both in steel and reinforced concrete, and their openings should be designed according to a reference grain diameter. This key parameter is often chosen arbitrarily due to the difficulties in considering the full grain size distribution of the deposit. Sufficiently small outlets, however, leads to premature clogging of the barriers, blocking further outflow (Ashour et al., 2017). This can result in excessive maintenance costs.</p><p>This work focuses on the clogging mechanism of three different kinds of filter barriers: nets, slit dams, and slot dams. The aim is to evaluate the influence of grainsize dispersity into the clogging/non-clogging transition. Starting from simpler monodisperse granular material, we determine via DEM simulations the particle diameter D that induces clogging in the openings, as a function of the opening size S. Thus, for monodisperse grains, a set of threshold values for S/D can be detected: on one side of the threshold the particles are too small to clog the opening, on the other side they are too large to allow free passage of the material.</p><p>However, natural debris deposits are far from uniform. To analyse the role of grainsize dispersity, bidisperse specimens are created mixing grains with two different diameters: a small diameter and a large diameter. By varying the composition of large and small particles, a transition is observed between clogging and free-flow, in analogy with what obtained in the simulation with monodisperse grains. The comparison of results obtained with bidisperse and monodisperse samples indicates that an analogy in terms of trends and thresholds exists, as long as an equivalent diameter D* is introduced for bidisperse mixtures (Marchelli, 2018). This parameter is therefore suggested as the reference diameter to be adopted in the barrier design.</p>

Thermomechanical Characterization of SMA Actuators Under Cyclic Loading

Aerospace ◽  
2003 ◽  
Author(s):  
Dimitris C. Lagoudas ◽  
Pavlin B. Entchev ◽  
Parikshith K. Kumar
Keyword(s):  
Heat Treatment ◽  
Cyclic Loading ◽  
Mechanical Loading ◽  
Large Diameter ◽  
High Energy ◽  
High Energy Density ◽  
Treatment Conditions ◽  
Loading Patterns ◽  
Superelastic Behavior ◽  
Different Diameters

Shape memory alloy (SMA) wire actuators have been increasingly used in various devices and applications due to their high energy density and simple design. With the use of these actuators the questions of size effects on their behavior need to be addressed. This paper presents a study on the cyclic loading behavior of large diameter SMA wires subjected to different thermo-mechanical loading paths. Wires of two different diameters are investigated in the current study—1.78 mm and 2.16 mm. The issues addressed in this work include the investigation and design of a gripping technique for the large diameter wires to avoid slippage and study of heat treatment conditions for optimized superelastic behavior. After the heat treatment, specimens are subjected to cyclic mechanical loading. Two different cyclic loading patterns have been investigated: loading up to a given value of stress or up to a given value of strain.

Numerical Modeling of Local Scour Below a Piggyback Pipeline in Currents

2006 ◽  
Author(s):  
Ming Zhao ◽  
Liang Cheng
Keyword(s):  
Stokes Equations ◽  
Large Diameter ◽  
Mass Conservation ◽  
Sediment Concentration ◽  
Conservation Equation ◽  
Diameter Ratio ◽  
Local Scour ◽  
Navier Stokes ◽  
Bed Scour ◽  
Different Diameters

Local scour under two pipelines of different diameters in steady currents is investigated numerically. The two pipelines are arranged in the so-called piggyback configuration where the small pipeline is located directly above the large pipeline (as shown in Fig. 1). The Reynolds-averaged Navier-Stokes equations and the transport equation of the suspended sediment concentration are solved using a finite element method. The sediment mass conservation equation is solved for predicting the bed scour profile. The numerical model is firstly validated against the scour below a single pipeline where the experimental data are available. Then the model is employed to simulate the scour below two pipelines in steady currents. Computations are carried out for the diameter ratio (the small pipe diameter (d) to the larger one (D)) of 0.2 and the gap (G, between the two pipelines) to the large diameter ratio G/D ranging from 0.0 to 0.5. It is found that the flow and the scour profiles are influenced significantly by the gap ratio.

Symmetric Beauty: Multi-Point Press Based on Parallel and Synchronous Toggle Mechanism Driven by Pneumatic Muscle

2011 ◽  
Vol 201-203 ◽  
pp. 2745-2748
Author(s):  
Pei Liang Qin ◽  
Ming Di Wang ◽  
Kang Min Zhong
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Pneumatic Cylinder ◽  
Full Account ◽  
Pneumatic Muscle ◽  
Large Ratio ◽  
Output Force ◽  
The Press ◽  
New Type ◽  
Different Diameters

Compared with the traditional rigid pneumatic cylinder, the pneumatic muscle has many outstanding advantages such as large ratio between output force and diameter, large ratio between output force and weight. However, it can only provide the tension, can not provide the thrust force, it is a one-orientation output force component. In this paper, two different diameters pneumatic muscle, combined with the parallel and synchronous toggle force-amplified mechanism,a new type of multi-point press has been innovated. The large-diameter pneumatic muscle will be used for the working stroke of the pressure travel, while the small-diameter pneumatic muscle will be used for the return travel. The tension of the pneumatic muscle will decrease with the increases of the contraction; the force-amplified coefficient of the toggle mechanism will increase with the decrease of the pressure angle, which is taken full account of this complementary relationship between them. So the output force curve of the press is improved smoothly.

Liquid Supply and Heat Transfer Performance of Sintered Cu Monolayer Wicks for Phase Change Heat Transfer Applications

2011 ◽  
Author(s):  
Stephen Sharratt ◽  
Youngsuk Nam ◽  
Y. Sungtaek Ju
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Large Diameter ◽  
High Heat ◽  
Heat Fluxes ◽  
Powder Size ◽  
Transfer Performance ◽  
Porous Layers ◽  
Different Diameters ◽  
Phase Change Heat Transfer

When combined with a bi-porous or a vertical liquid artery structure, thin porous layers of high thermal conductivity materials can provide high critical heat flux while maintaining low thermal resistance. They are therefore are very promising for applications in advanced heat pipes and vapor chambers. The present study characterizes the liquid supply and heat transfer performance of monolayers of sintered Cu powders. Three sets of monolayer samples are prepared by sintering Cu powders with different diameters (29, 59, 71 um). The measured heat transfer performance is relatively insensitive to the powder diameter in the low flux regime. At relatively high heat fluxes (> 20 W/cm2) monolayers with the two large diameter powders show similar liquid supply and heat transfer performance while the sample with the smallest powder size shows significantly degraded heat transfer performance due to local dryouts.

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