scholarly journals Design, Simulation, Fabrication and Testing of a Bio-Inspired Amphibious Robot with Multiple Modes of Mobility

2012 ◽  
Vol 24 (4) ◽  
pp. 629-641 ◽  
Author(s):  
Alexander S. Boxerbaum ◽  
◽  
Matthew A. Klein ◽  
Jeffery E. Kline ◽  
Stuart C. Burgess ◽  
...  
Keyword(s):  
Surf Zone ◽  
Sandy Beaches ◽  
Proof Of Concept ◽  
Biologically Inspired ◽  
Animal Locomotion ◽  
Design And Optimization ◽  
Moist Sand ◽  
Aquatic Locomotion ◽  
Versus Range ◽  
Amphibious Robot

Surf-zone environments represent an extreme challenges to robot operation. A robot that autonomously navigates rocky terrain, constantly changing underwater currents, hard-packed moist sand and loose dry sand characterizing this environment, would have significant utility in a range of defence and civilian missions. The study of animal locomotion mechanisms can elucidate specific movement principles that can be applied to address these demands. In this work, we report on the design and optimization of a biologically inspired amphibious robot for deployment and operation in an ocean beach environment. We specifically report a new design fusing a range of insectinspired passive mechanisms with active autonomous control architectures to seamlessly adapt to and traverse a range of challenging substrates both in and out of the water, and the design and construction of SeaDog, a proof-of-concept amphibious robot built for navigating rocky or sandy beaches and turbulent surf zones. The robot incorporates a layered hull and chassis design that is integrated into a waterproof Explorer Case in order to provide a large, protected payload in an easy-to-carry package. It employs a rugged drivetrain with four wheel-legs and a unique tail design and actuation strategy to aid in climbing, swimming and stabilization. Several modes of terrestrial and aquatic locomotion are suggested and tested versus range of mobility metrics, including data obtained in simulation and hardware testing. A waterproofing strategy is also tested and discussed, providing a foundation for future generations of amphibious mobile robots.

scholarly journals Emergence and Migration of a Nearshore Bar: Sediment Flux and Morphological Change on a Multi-Barred Beach in the Great Lakes

2007 ◽  
Vol 60 (1) ◽  
pp. 31-47 ◽  
Author(s):  
Brian Greenwood ◽  
Allana Permanand-Schwartz ◽  
Christopher A. Houser
Keyword(s):  
Great Lakes ◽  
Suspended Sediment ◽  
Surf Zone ◽  
Sandy Beaches ◽  
Sediment Flux ◽  
Accommodation Space ◽  
Longshore Transport ◽  
Sediment Balance ◽  
And Migration ◽  
Equilibrium Morphology

Abstract Burley Beach (southeastern Lake Huron) exhibits a multi-barred shoreface, the long-term equilibrium morphology characteristic of many low angle, sandy beaches in the Canadian Great Lakes. During a single major storm, a new bar emerged 50-60 m offshore as an irregular trough-crest form, through differential erosion of an existing shore terrace. Emergence, bar growth and offshore migration were associated with: (a) an overall negative sediment balance in the inner surf zone initially (‑2.30 m3>/m beach width), but with a large positive sediment balance (+5.10 m3/m) subsequent to the storm peak and during the storm decay; (b) progradation of the beach step to produce a new shore terrace; and (c) offshore migration of the two outer bars to provide the accommodation space necessary for the new bar. The primary transport mechanisms accounting for emergence of the new bar, its growth and migration were: (a) the mean cross-shore currents (undertow), which always transported suspended sediment offshore; and (b) the onshore transport of suspended sediment by incident gravity wave frequencies early in the storm and subsequently by infragravity waves (at the storm peak and the decay period). The longshore transport of sediment was significant in terms of the gross transport, although the net result was only a small transport to the south-west (historic littoral transport direction). It did not cause bar initiation, but it may have supplied some of the sediment for bar growth. The primary mechanism for bar initiation and growth was the cross-shore displacement of sediment by wave-driven (oscillatory) transport and cross-shore mean currents (undertow).

scholarly journals Ecomorphology and food habits of teleost fishes Trachinotus carolinus (Teleostei: Carangidae) and Menticirrhus littoralis (Teleostei: Sciaenidae), inhabiting the surf zone off Niterói, Rio de Janeiro, Brazil

2010 ◽  
Vol 58 (spe4) ◽  
pp. 1-9 ◽  
Author(s):  
Luana Prestrelo Palmeira ◽  
Cassiano Monteiro-Neto
Keyword(s):  
Fish Species ◽  
Food Habits ◽  
Diet Composition ◽  
Surf Zone ◽  
Fish Larvae ◽  
Sandy Beaches ◽  
Size Class ◽  
Class I ◽  
Teleost Fishes ◽  
Food Items

The ecomorphology and food habits of juvenile Trachinotus carolinus and Menticirrhus littoralis caught in the surf zone of sandy beaches in Niterói, RJ, were investigated between July 2006 and May 2007. These fish species differ morphologically, but present similarities in their diet composition suggest some slight overlapping in their diet. The importance of food items was assessed using Kawakami and Vazzoler's feeding index. Morphometric variables were recorded to correlate with the diet composition of the different size classes for each species. A total of 210 fishes (Trachinotus carolinus - 122, Menticirrhus littoralis - 88), ranging between 24.2 mm and 112 mm total length, were analyzed, but the stomachs of only 84.8% of them contained food. Trachinotus carolinus presented mysids, Polychaetes and Emerita spp. as the predominant items in their diet. Formicidae and Isopoda were the most important items for class I individuals, whereas mysids and Emerita spp. were important for classes II and III. Class I individuals also showed smaller sized prey (amphipods and isopods) and clupeid fish larvae in their diet. Emerita spp. dominated the food items of Menticirrhus littoralis regardless of the size class. Polychaetes, the second most important item was better represented in class sizes II and III. The main morphometric variable correlated with such differences included mouth position and diameter of the eye.

An amphibious robot for surf zone science and environmental monitoring

OCEANS 2009 ◽  
2009 ◽  
Author(s):  
T. R. Consi ◽  
B. R. Ardaugh ◽  
T. R. Erdmann ◽  
M. Matsen ◽  
M. Peterson ◽  
...  
Keyword(s):  
Environmental Monitoring ◽  
Surf Zone ◽  
Amphibious Robot

MODELING SPILLED OIL PARTITIONING IN NEARSHORE AND SURF ZONE AREAS

1985 ◽  
Vol 1985 (1) ◽  
pp. 379-383 ◽  
Author(s):  
Erich R. Gundlach ◽  
Timothy W. Kana ◽  
Paul D. Boehm
Keyword(s):  
Wave Energy ◽  
Surf Zone ◽  
High Energy ◽  
Sandy Beaches ◽  
Coarse Grained ◽  
Tidal Range ◽  
Incoming Wave ◽  
Fine Grained ◽  
Beach Sediments ◽  
Rocky Coasts

ABSTRACT The shoreline of a potential spill impact area can be divided into units, each with a specific geomorphology. As oil enters each unit, it will (to varying extents) evaporate, dissolve, interact with suspended particles and sink, biodegrade, photo-oxidize, be transported to the next unit, or strand on the shoreline. In the last case, oil will reenter the aquatic system after a given time and again be exposed to these same processes. For modeling purposes, the world's shorelines can be divided into sedimentary beaches and tectonic rocky coasts, varying in wave energy and tidal range. The size of beach sediments can range from very coarse grained (gravels) to very fine grained (silts and clays). Coarse-grained shorelines have higher incoming wave energy than fine-grained areas. Along all coasts, several partitioning components remain relatively constant for medium to light crude oils, e.g., evaporation (30 to 50 percent) and biodegradation/photo-oxidation (0 to 5 percent). Others may vary substantially. For instance, sedimentation may reach 10 to 20 percent in fine-grained estuaries, but only 0 to 2 percent along high energy coasts having very coarse-grained bottom sediments. Similarly, along sandy beaches the stranding of oil along the shoreline may reach 25 to 35 percent, as compared to only 1 to 2 percent along steep, rocky coasts. Dissolution, in general, does not vary so radically, being approximately 10 to 15 percent along high-energy rocky coasts, as compared to 5 to 10 percent in sheltered estuaries that do not have the mixing energy to drive additional oil into the water column.

Application of an Air-Curtain Fluidic Jet Type Seal to Reduce Turbine Shroud Leakage

2013 ◽  
Author(s):  
Alison Auld ◽  
Michael Hilfer ◽  
Simon Hogg ◽  
Grant Ingram ◽  
Andrew Messenger
Keyword(s):  
Output Power ◽  
High Speed ◽  
Leakage Flow ◽  
Proof Of Concept ◽  
Shear Forces ◽  
Air Curtain ◽  
Design And Optimization ◽  
Tip Leakage ◽  
Seal Design ◽  
Turbine Output

This paper describes the design and optimization of an ‘air-curtain’ type seal using a fluidic jet to reduce tip leakage losses on a small high-speed single stage axial turbine device. The application will essentially demonstrate proof of concept for turbomachinery applications, opening the door for the development of future designs for applications in all scales of turbomachine. CFD is used to develop and optimize the seal design. The performance benefit from applying the new seal is predicted. These calculations illustrate the importance of accurately accounting for the effects of the sealing jet on shroud shear forces, in addition to leakage flow reduction, when determining the overall gain in turbine output power from the improved sealing. It is planned to validate the new seal design in full-scale turbine tests, during the next phase of the work.

Macrobenthic surf zone communities of temperate sandy beaches: spatial and temporal patterns

2014 ◽  
Vol 36 (3) ◽  
pp. 326-336 ◽  
Author(s):  
Cecilia Carcedo ◽  
Sandra Fiori ◽  
Claudia Bremec
Keyword(s):  
Surf Zone ◽  
Temporal Patterns ◽  
Sandy Beaches ◽  
Spatial And Temporal Patterns

scholarly journals One-time learning in a biologically-inspired Salience-affected Artificial Neural Network (SANN)

2019 ◽  
Author(s):  
Leendert A Remmelzwaal ◽  
George F R Ellis ◽  
Jonathan Tapson
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Neural Dynamics ◽  
Proof Of Concept ◽  
Activation Functions ◽  
Learning Networks ◽  
Biologically Inspired ◽  
Artificial Neural ◽  
Validation Testing ◽  
And Robotics

AbstractIn this paper we introduce a novel Salience Affected Artificial Neural Network (SANN) that models the way neuromodulators such as dopamine and noradrenaline affect neural dynamics in the human brain by being distributed diffusely through neocortical regions. This allows one-time learning to take place through strengthening entire patterns of activation at one go. We present a model that accepts a salience signal, and returns a reverse salience signal. We demonstrate that we can tag an image with salience with only a single training iteration, and that the same image will then produces the highest reverse salience signal during classification. We explore the effects of salience on learning via its effect on the activation functions of each node, as well as on the strength of weights in the network. We demonstrate that a salience signal improves classification accuracy of the specific image that was tagged with salience, as well as all images in the same class, while penalizing images in other classes. Results are validated using 5-fold validation testing on MNIST and Fashion MNIST datasets. This research serves as a proof of concept, and could be the first step towards introducing salience tagging into Deep Learning Networks and robotics.

scholarly journals Surf Zone Turbulence and Suspended Sediment Dynamics—A Review

2021 ◽  
Vol 9 (11) ◽  
pp. 1300
Author(s):  
Troels Aagaard ◽  
Joost Brinkkemper ◽  
Drude F. Christensen ◽  
Michael G. Hughes ◽  
Gerben Ruessink
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Surf Zone ◽  
Sediment Concentration ◽  
Sandy Beaches ◽  
Suspended Sediment Transport ◽  
Velocity Signal ◽  
Wave Phase ◽  
Turbulence Production

The existence of sandy beaches relies on the onshore transport of sand by waves during post-storm conditions. Most operational sediment transport models employ wave-averaged terms, and/or the instantaneous cross-shore velocity signal, but the models often fail in predictions of the onshore-directed transport rates. An important reason is that they rarely consider the phase relationships between wave orbital velocity and the suspended sediment concentration. This relationship depends on the intra-wave structure of the bed shear stress and hence on the timing and magnitude of turbulence production in the water column. This paper provides an up-to-date review of recent experimental advances on intra-wave turbulence characteristics, sediment mobilization, and suspended sediment transport in laboratory and natural surf zones. Experimental results generally show that peaks in the suspended sediment concentration are shifted forward on the wave phase with increasing turbulence levels and instantaneous near-bed sediment concentration scales with instantaneous turbulent kinetic energy. The magnitude and intra-wave phase of turbulence production and sediment concentration are shown to depend on wave (breaker) type, seabed configuration, and relative wave height, which opens up the possibility of more robust predictions of transport rates for different wave and beach conditions.

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