Sensing of minute airflow motions near walls using pappus-type nature-inspired sensors

This work describes the development and use of pappus-like structures as sensitive sensors to detect minute air-flow motions. We made such sensors from pappi taken from nature-grown seed, whose filiform hairs' length-scale is suitable for the study of large-scale turbulent convection flows. The stem with the pappus on top is fixated on an elastic membrane on the wall and tilts under wind-load proportional to the velocity magnitude in direction of the wind, similar as the biological sensory hairs found in spiders, however herein the sensory hair has multiple filiform protrusions at the tip. As the sensor response is proportional to the drag on the tip and a low mass ensures a larger bandwidth, lightweight pappus structures similar as those found in nature with documented large drag are useful to improve the response of artificial sensors. The pappus of a Dandelion represents such a structure which has evolved to maximize wind-driven dispersion, therefore it is used herein as the head of our sensor. Because of its multiple hairs arranged radially around the stem it generates uniform drag for all wind directions. While still being permeable to the flow, the hundreds of individual hairs on the tip of the sensor head maximize the drag and minimize influence of pressure gradients or shear-induced lift forces on the sensor response as they occur in non-permeable protrusions. In addition, the flow disturbance by the sensor itself is limited. The optical recording of the head-motion allows continuously remote-distance monitoring of the flow fluctuations in direction and magnitude. Application is shown for the measurement of a reference flow under isothermal conditions to detect the early occurrence of instabilities

Final Report for the ZERT Project: Basic Science of Retention Issues, Risk Assessment & Measurement, Monitoring and Verification for Geologic Sequestration

ZERT has made major contributions to five main areas of sequestration science: improvement of computational tools; measurement and monitoring techniques to verify storage and track migration of CO{sub 2}; development of a comprehensive performance and risk assessment framework; fundamental geophysical, geochemical and hydrological investigations of CO{sub 2} storage; and investigate innovative, bio-based mitigation strategies

Projective ICP and Stabilizing Architectural Augmented Reality Overlays

This paper extends the concept to projective point matching, in which shapes are related by a projective transform rather than a Euclidean transform. With this extended technique, we show that directly registering 2D Augmented Reality (AR) overlays via a projective transform has greater registration stability than the more usual technique of estimating the 3D position of the overlay and then applying pinhole projection, which can produce noticeable frame-rate jitter of the graphical objects. Moreover, the technique does not rely on explicit feature point correspondence and tracking. We then further extend the technique to directly register 3D shapes projectively by using mutually constrained 2D projective mappings. These two new techniques enhance the repertoire of methods for producing high-detail, stable augmentation of built scenes. Keywords: Augmented Reality stabilization, Iterative Closest Point 1 Introduction One of the fundamental operations