201219 Dust Detection by Antenna Instruments

Title:
Dust Detection by Antenna Instruments

Speaker:
沈明學 (Ming-Hsueh Shen), PhD candidate, University of Colorado Boulder

Time:
12/19 (Sat.) 7 pm PST, 8 pm MST, 9 pm CST, 10 pm EST
12/20 (Sun.) 11 am Taiwan

Keywords:
planetary science, cosmic dust, dust detection, antenna instruments, induced charging

Abstract:
Space missions often carry antenna instruments that are sensitive to dust impacts, however, the understanding of signal generation mechanisms has been lacking. A signal generation model in an analytical form is presented that provides a good agreement with laboratory simulation measurements. The model is based on direct and induced charging of the spacecraft from the collected and escaping fraction of free charges from the impact-generated plasma cloud. A set of laboratory experiments is performed using a 20:1 scaled-down model of the Cassini spacecraft using a dust accelerator facility. The results show that impact plasmas can be modeled as a plume of ions streaming away from the impact location and a cloud of isotropically expanding electrons. The fitting of the model to the collected antenna waveforms provides the key parameters of impact plasma.

201212 Adaptive Radiative Heat Management: A Multispectral Chameleon for Energy and Health

Title:
Adaptive Radiative Heat Management: A Multispectral Chameleon for Energy and Health

Speaker:
徐伯均(Po-Chun Hsu), PhD, Duke University

Time:
12/12 (Sat.) 7 pm PST, 8 pm MST, 9 pm CST, 10 pm EST
12/13 (Sun.) 11 am Taiwan

Keywords:
materials science, photonics and heat transfer, radiative cooling, solar thermal, nanophotonics

Abstract:
The space heating and cooling energy consumption of buildings accounts for about 15% of total energy consumption and 10% of greenhouse gas emissions in the United States. This energy consumption, while enormous, is not surprising because thermal comfort is one of the most fundamental needs for human beings. As global warming and climate change become more serious, it is critical to advance our thermal science and engineering to overcome traditional energy efficiency limits. In this talk, I will introduce recent work in thermal management for energy and health applications, focusing on multispectral photon engineering and heat transfer designs from nano to macroscale.