More Like this

1. Ground squirrels

   https://doi.org/10.1016/j.cub.2022.02.015  

   Pra, Rafael Dai; Bagriantsev, Sviatoslav N.; Gracheva, Elena O. (June 2022, Current Biology)
2. Developing Team Ground Rules

   Bennett, J; Marchetti, C; Bailey, M; Blackwell, G; Rivero, I (May 2025, Open Science Framework)

   Ground rules reflect what is important to team members about how they interact and can promote inclusion within the team 

   more » « less
3. Boots on the Ground at Yaxnohcah: Ground-Truthing Lidar in a Complex Tropical Landscape

   https://doi.org/10.7183/2326-3768.4.3.314  

   Reese-Taylor, Kathryn; Hernández, Armando Anaya; Esquivel, F. C.; Monteleone, Kelly; Uriarte, Alejandro; Carr, Christopher; Acuña, Helga Geovannini; Fernandez-Diaz, Juan Carlos; Peuramaki-Brown, Meaghan; Dunning, Nicholas (August 2016, Advances in Archaeological Practice)

   Este trabajo propone un método de muestreo a fin de contrastar en el terreno los datos obtenidos a partir de imágenes LiDAR, que permitan al investigador verificar y/o predecir la precisión de los resultados sobre un área mayor. El estudio de caso aquí presentado se centra en el sitio de Yaxnohcah, ubicado en la Meseta Cárstica Central de la península de Yucatán. Está área se caracteriza por presentar una variedad de densos bosques tropicales húmedos y zonas de vegetación de humedal con pocos accesos de caminos y brechas. Para este estudio se seleccionaron veintiún bloques de 100 por 100 metros del área, que comprendió una muestra estratificada del 10 por ciento, e incluyeron ejemplos de varias zonas de vegetación distinta. Se realizó un recorrido de superficie por transectos a lo largo de los bloques, registrándose dos tipos de errores. Los Errores del Tipo 1 consisten de rasgos culturales identificados en campo, pero que no aparecen en el los Modelos Digital de Elevación (MDE) o en el Modelo de Superficie Digital (MSE). Los Errores de Tipo 2 consisten en rasgos que parecen culturales en el MDE o MSE, pero que en realidad son causadas por diferentes tipos de vegetación. De manera concurrente, realizamos un extenso reconocimiento de la vegetación en cada bloque, identificando las principales especies presentes, las diferentes alturas de dosel, así como las características generales de la topografía y los suelos. Los resultados del método de contrastación en el terreno demuestran que los datos lidar son sumamente confiables y es posible utilizar una muestra a fin de evaluar la precisión, la veracidad y la certidumbre de los datos sobre un área mayor. 

   more » « less
4. Granular Jamming Feet Enable Improved Foot-Ground Interactions for Robot Mobility on Deformable Ground

   Chopra, Shivam Tolley (April 2020, IEEE robotics automation letters)

   Recent studies on dynamic legged locomotion have focused on incorporating passive compliant elements into robot legs which can help with energy efficiency and stability, enabling them to work in wide range of environments. In this work, we present the design and testing of a soft robotic foot capable of active stiffness control using granular jamming. This foot is designed and tested to be used on soft, flowable ground such as sand. Granular jamming feet enable passive foot shape change when in contact with the ground for adaptability to uneven surfaces, and can also actively change stiffness for the ability to apply sufficient propulsion forces. We seek to study the role of shape change and stiffness change in foot-ground interactions during foot-fall impact and shear. We have measured the acceleration during impact, surface traction force, and the force to pull the foot out of the medium for different states of the foot. We have demonstrated that the control of foot stiffness and shape using the proposed foot design leads to improved locomotion, specifically an approximately 52% reduced foot deceleration at the joints after impact, an approximately 63% reduced depth of penetration in the sand on impact, higher shear force capabilities for a constant depth above the ground, and an approximately 98% reduced pullout force compared to a rigid foot. 

   more » « less
5. Exact solutions for ground effect

   https://doi.org/10.1017/jfm.2020.149  

   Baddoo, Peter J.; Kurt, Melike; Ayton, Lorna J.; Moored, Keith W. (May 2020, Journal of Fluid Mechanics)

   ‘Ground effect’ refers to the enhanced performance enjoyed by fliers or swimmers operating close to the ground. We derive a number of exact solutions for this phenomenon, thereby elucidating the underlying physical mechanisms involved in ground effect. Unlike previous analytic studies, our solutions are not restricted to particular parameter regimes, such as ‘weak’ or ‘extreme’ ground effect, and do not even require thin aerofoil theory. Moreover, the solutions are valid for a hitherto intractable range of flow phenomena, including point vortices, uniform and straining flows, unsteady motions of the wing, and the Kutta condition. We model the ground effect as the potential flow past a wing inclined above a flat wall. The solution of the model requires two steps: firstly, a coordinate transformation between the physical domain and a concentric annulus; and secondly, the solution of the potential flow problem inside the annulus. We show that both steps can be solved by introducing a new special function which is straightforward to compute. Moreover, the ensuing solutions are simple to express and offer new insight into the mathematical structure of ground effect. In order to identify the missing physics in our potential flow model, we compare our solutions against new experimental data. The experiments show that boundary layer separation on the wing and wall occurs at small angles of attack, and we suggest ways in which our model could be extended to account for these effects. 

   more » « less