Browsing by Author "Chang, Chih-Li"

Now showing 1 - 3 of 3

A Low Cost C-band SAR Small Satellite Definition for Disasters Management
(2014)
Yaung, James Yu-Chen
;
Chung, Shyh-Jong
;
Lee, Yun-Jui
;
Tarn, I-Young
;
Wu, Bor-Han
Monsoons and typhoons bring along heavy precipitation and they can cause significant disasters in Taiwan in addition to earthquakes. Ever since a small satellite SAR mission was defined and published in APSAR2011 [1], the mission has been analyzed for seeking a feasible development solution with little critical technolgoy item. This work revealed a C-band small satellite payload definition solution and it was published in APSAR2013 [2]. Now, a skilful power combining technique using GaN SSPA products is identified as the enabling technology to substantiate the C-band system defined. Consequently, a satellite definition work has been initated in NSPO.
A Small Satellite C-band SAR Mission Payload Definition for Disasters Management
(2013)
Yaung, James Yu-Chen
;
Chen, Kun-Shan
;
Chung, Shyh-Jong
;
Yu, Shiann-Jeng
;
Hung, Hao-Lun
Taiwan is an island with various high mountains created by tectonic plate collision where continent building is still active with numerous earthquake activities. Taiwan is also in one of the most prevalent monsoon and typhoon areas and they can bring along heavy precipitation that produce great threat of mud slide and land slide in the mountains. Remote mountain areas can only rely on satellite monitoring before, during, and after heavy rains where the optical monitoring satellites won\'t be able to provide the timely data or information. SAR satellites, with their advantages of all-weather capability, repeat pass, fine spatial resolution and wide swath, can provide coverage at disaster locations in the island, disaster assessment and resource survey provided the operating frequency to be lower enough as indicated in the low cost C-band SAR satellite payload defined in this paper. Based on the payload technology tradeoff analysis, the C-band system with GaN SSPA power amplifier was selected by comparing it with the X-band system with the TWTA technology which was described in our early stage of mission definition and analysis.
Low-toxic cycloplatinated polymer dots with rational design of acceptor comonomers for enhanced photocatalytic efficiency and stability
(2020-07-05)
Chang, Chih-Li
;
Lin, Wei-Cheng
;
Jia, Chuan-Yu
;
Ting, Li-Yu
;
Jayakumar, Jayachandran
By mimicking nature photosynthesis, a library of cycloplatinated polymer dots (Pdots) and pristine Pdots are presented and investigated the importance of selecting acceptor comonomers. A clear design strategy for the selection of acceptor comonomers of Pdots to achieve environmental-friendly, high efficiency, and long stability of photocatalytic reaction can be understood. The active PFTBTA-PtPy Pdots provide the excellent hydrogen evolution rates up to 7.34 +/- 0.82 mmol h(-1) g(-1) under a methanol-free solution and visible-light-driven system. MTT assay experiments confirm the use of the cycloplatinated Pdots as photocatalysts can minimize the toxicity, relative to the conventional approach that directly adding Pt into a solution system. Furthermore, the Pdots can be reactivated for hydrogen generation by the recycling process. The result proves that the use of cycloplatinated Pdots can not only enhance the HER efficiency and stability but also reduce the toxicity.