scholarly journals Propulsive design principles in a multi-jet siphonophore

2018 ◽  
Author(s):  
Kelly R. Sutherland ◽  
Sean P. Colin ◽  
John H. Costello ◽  
Brad J. Gemmell
Keyword(s):  
High Speed ◽  
Swimming Performance ◽  
Dimensional Space ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Flow Parameters ◽  
Image Velocimetry ◽  
Summary Statement ◽  
High Pressure Region ◽  
Three Dimensional Space

AbstractCoordination of multiple propulsors can provide performance benefits in swimming organisms. Siphonophores are marine colonial organisms that orchestrate the motion of multiple swimming zooids for effective swimming. However, the kinematics at the level of individual swimming zooids (nectophores) have not been examined in detail. We used high speed, high resolution microvideography and particle image velocimetry (PIV) of the physonect siphonophore, Nanomia bijuga, to study the motion of the nectophores and the associated fluid motion during jetting and refilling. The integration of nectophore and velum kinematics allow for a high-speed (maximum ~1 m s−1), narrow (1-2 mm) jet and rapid refill as well as a 1:1 ratio of jetting to refill time. Overall swimming performance is enhanced by velocity gradients produced in the nectophore during refill, which lead to a high pressure region that produces forward thrust. Generating thrust during both the jet and refill phases augments the distance travelled by 17% over theoretical animals, which generate thrust only during the jet phase. The details of velum kinematics and associated fluid mechanics elucidate how siphonophores effectively navigate three-dimensional space and could be applied to exit flow parameters in multijet underwater vehicles.Summary statement:Colonial siphonophores produce high speed jets and generate forward thrust during refill using a flexible velum to achieve effective propulsion.

scholarly journals Maneuvering Performance in the Colonial Siphonophore, Nanomia bijuga

Biomimetics ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 62
Author(s):  
Kelly R. Sutherland ◽  
Brad J. Gemmell ◽  
Sean P. Colin ◽  
John H. Costello
Keyword(s):  
Angular Velocity ◽  
High Speed ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Complex Environments ◽  
Pulsed Jets ◽  
Image Velocimetry ◽  
Underwater Propulsion ◽  
Turning Radius ◽  
Three Dimensional Space

The colonial cnidarian, Nanomia bijuga, is highly proficient at moving in three-dimensional space through forward swimming, reverse swimming and turning. We used high speed videography, particle tracking, and particle image velocimetry (PIV) with frame rates up to 6400 s−1 to study the kinematics and fluid mechanics of N. bijuga during turning and reversing. N. bijuga achieved turns with high maneuverability (mean length–specific turning radius, R/L = 0.15 ± 0.10) and agility (mean angular velocity, ω = 104 ± 41 deg. s−1). The maximum angular velocity of N. bijuga, 215 deg. s−1, exceeded that of many vertebrates with more complex body forms and neurocircuitry. Through the combination of rapid nectophore contraction and velum modulation, N. bijuga generated high speed, narrow jets (maximum = 1063 ± 176 mm s−1; 295 nectophore lengths s−1) and thrust vectoring, which enabled high speed reverse swimming (maximum = 134 ± 28 mm s−1; 37 nectophore lengths s−1) that matched previously reported forward swimming speeds. A 1:1 ratio of forward to reverse swimming speed has not been recorded in other swimming organisms. Taken together, the colonial architecture, simple neurocircuitry, and tightly controlled pulsed jets by N. bijuga allow for a diverse repertoire of movements. Considering the further advantages of scalability and redundancy in colonies, N. bijuga is a model system for informing underwater propulsion and navigation of complex environments.

scholarly journals Volumetric quantification of fluid flow reveals fish's use of hydrodynamic stealth to capture evasive prey

2014 ◽  
Vol 11 (90) ◽  
pp. 20130880 ◽  
Author(s):  
Brad J. Gemmell ◽  
Deepak Adhikari ◽  
Ellen K. Longmire
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Trophic Levels ◽  
Small Fish ◽  
Major Pathway ◽  
Image Velocimetry ◽  
Highly Sensitive ◽  
Volumetric Quantification

In aquatic ecosystems, predation on zooplankton by fish provides a major pathway for the transfer of energy to higher trophic levels. Copepods are an abundant zooplankton group that sense hydromechanical disturbances produced by approaching predators and respond with rapid escapes. Despite this capability, fish capture copepods with high success. Previous studies have focused on the predatory strike to elucidate details of this interaction. However, these raptorial strikes and resulting suction are only effective at short range. Thus, small fish must closely approach highly sensitive prey without triggering an escape in order for a strike to be successful. We use a new method, high-speed, infrared, tomographic particle image velocimetry, to investigate three-dimensional fluid patterns around predator and prey during approaches. Our results show that at least one planktivorous fish ( Danio rerio ) can control the bow wave in front of the head during the approach and consumption of prey (copepod). This alters hydrodynamic profiles at the location of the copepod such that it is below the threshold required to elicit an escape response. We find this behaviour to be mediated by the generation of suction within the buccopharyngeal cavity, where the velocity into the mouth roughly matches the forward speed of the fish. These results provide insight into how animals modulate aspects of fluid motion around their bodies to overcome escape responses and enhance prey capture.

Research on the Three-Dimensional Velocity Field Splitting Measurement Method of Cavitations-Impinging Stream Reactor

2012 ◽  
Vol 571 ◽  
pp. 618-621
Author(s):  
Qin Li ◽  
Fu Bao Li ◽  
Zhong Ke Li ◽  
De Xi Wang
Keyword(s):  
Velocity Field ◽  
Dimensional Space ◽  
Splitting Method ◽  
Three Dimensional ◽  
Ccd Camera ◽  
Light Emitting ◽  
Basic Measurement ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Three Dimensional Space

In the Particle image velocimetry (PIV) measurement system, using the basic measurement principles of three-dimensional space position and splitting method, it, using a CCD camera, achieved the measurement to a space position. Light emitting diodes flash twice and image in the same CCD camera and space vector can be obtained directly by the image processing, and then three-dimensional velocity field can be obtained.

scholarly journals A Piecewise Hysteresis Model for a Damper of HIS System

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Kaidong Tian ◽  
Bangji Zhang ◽  
Nong Zhang ◽  
Xuhui Liu ◽  
Jinchen Ji
Keyword(s):  
High Speed ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Hysteresis Phenomenon ◽  
Hysteresis Model ◽  
Low Speed ◽  
Proposed Model ◽  
Velocity Characteristic ◽  
Force Velocity ◽  
Three Dimensional Space

A damper of the hydraulically interconnected suspension (HIS) system, as a quarter HIS, is prototyped and its damping characteristic is tested to characterize the damping property. The force-velocity characteristic of the prototype is analyzed based on a set of testing results and accordingly a piecewise hysteresis model for the damper is proposed. The proposed equivalent parametric model consists of two parts: hysteresis model in low speed region and saturation model in high speed region which are used to describe the hysteresis phenomenon in low speed and nonhysteresis phenomenon in high speed, respectively. The parameters of the model are identified based on genetic algorithm by setting the constraints of parameters according to their physical significances and the corresponding testing results. The advantages of the model are highlighted by comparing to the nonhysteresis model and the permanent hysteresis model. The numerical simulation results are compared with the testing results to validate the accuracy and effectiveness of the proposed model. Finally, to further verify the proposed model’s wide applicability under different excitation conditions, its results are compared to the testing results in three-dimensional space. The research in this paper is significant for the dynamic analysis of the HIS vehicle.

scholarly journals Soft phototactic swimmer based on self-sustained hydrogel oscillator

2019 ◽  
Vol 4 (33) ◽  
pp. eaax7112 ◽  
Author(s):  
Yusen Zhao ◽  
Chen Xuan ◽  
Xiaoshi Qian ◽  
Yousif Alsaid ◽  
Mutian Hua ◽  
...  
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Modular Design ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Ambient Conditions ◽  
Solar Sails ◽  
Living Organisms ◽  
Light Material ◽  
Three Dimensional Space

Oscillations are widely found in living organisms to generate propulsion-based locomotion often driven by constant ambient conditions, such as phototactic movements. Such environment-powered and environment-directed locomotions may advance fully autonomous remotely steered robots. However, most man-made oscillations require nonconstant energy input and cannot perform environment-dictated movement. Here, we report a self-sustained soft oscillator that exhibits perpetual and untethered locomotion as a phototactic soft swimming robot, remotely fueled and steered by constant visible light. This particular out-of-equilibrium actuation arises from a self-shadowing–enabled negative feedback loop inherent in the dynamic light–material interactions, promoted by the fast and substantial volume change of the photoresponsive hydrogel. Our analytical model and governing equation unveil the oscillation mechanism and design principle with key parameters identified to tune the dynamics. On this autonomous oscillator platform, we establish a broadly applicable principle for converting a continuous input into a discontinuous output. The modular design can be customized to accommodate various forms of input energy and to generate diverse oscillatory behaviors. The hydrogel oscillator showcases agile life-like omnidirectional motion in the entire three-dimensional space with near-infinite degrees of freedom. The large force generated by the powerful and long-lasting oscillation can sufficiently overcome water damping and effectively self-propel away from a light source. Such a hydrogel oscillator–based all-soft swimming robot, named OsciBot, demonstrated high-speed and controllable phototactic locomotion. This autonomous robot is battery free, deployable, scalable, and integratable. Artificial phototaxis opens broad opportunities in maneuverable marine automated systems, miniaturized transportation, and solar sails.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

A Peptoid with Extended Shape in Water

2019 ◽  
Author(s):  
Jumpei Morimoto ◽  
Yasuhiro Fukuda ◽  
Takumu Watanabe ◽  
Daisuke Kuroda ◽  
Kouhei Tsumoto ◽  
...  
Keyword(s):  
Spectroscopic Analysis ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Biomolecular Recognition ◽  
Biological Application ◽  
New Class ◽  
Proteolytic Resistance ◽  
Pharmacokinetic Properties ◽  
Optically Pure ◽  
Three Dimensional Space

<div> <div> <div> <p>“Peptoids” was proposed, over decades ago, as a term describing analogs of peptides that exhibit better physicochemical and pharmacokinetic properties than peptides. Oligo-(N-substituted glycines) (oligo-NSG) was previously proposed as a peptoid due to its high proteolytic resistance and membrane permeability. However, oligo-NSG is conformationally flexible and is difficult to achieve a defined shape in water. This conformational flexibility is severely limiting biological application of oligo-NSG. Here, we propose oligo-(N-substituted alanines) (oligo-NSA) as a new peptoid that forms a defined shape in water. A synthetic method established in this study enabled the first isolation and conformational study of optically pure oligo-NSA. Computational simulations, crystallographic studies and spectroscopic analysis demonstrated the well-defined extended shape of oligo-NSA realized by backbone steric effects. The new class of peptoid achieves the constrained conformation without any assistance of N-substituents and serves as an ideal scaffold for displaying functional groups in well-defined three-dimensional space, which leads to effective biomolecular recognition. </p> </div> </div> </div>

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