Browsing by Author "Kao, Yu-Chi"

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A Field-Programmable Lab-on-a-Chip with Built-in Self-Test Circuit and Low-Power Sensor-Fusion Solution in 0.35 mu m Standard CMOS Process
(2015)
Lai, Kelvin Yi-Tse
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Shiu, Ming-Feng
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Lu, Yi-Wen
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Ho, Yingchieh
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Kao, Yu-Chi
This paper presents a field programmable lab-on-a-chip (FPLOC) with microfluidics actuation, droplet location/category readback, built-in-self-test (BIST), and bioassays detection. This FPLOC is composed of 1,800 MEDA microelectrodes and integrates a set of microfluidic operations to perform droplet moving/cutting/mixing. Besides, capacitive sensing circuits are considered for system automation, droplets classification, malfunctioning microelectrodes and surface flatness testing, and biomedical detection. Implemented in 0.35 mu m standard CMOS process in 7.4mm(2), the FPLOC demonstrates microfluidic operations under 25V at 1KHz, 1.3fF resolution for droplet location/category/chip BIST maps readback at 1MHz, and 0.34fF sensitivity of capacitive measurement window for biomedical detection at 1KHz.
High-resolution depth and coastline over major atolls of South China Sea from satellite altimetry and imagery
(2016-04)
Hsiao, Yu-Shen
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Hwang, Cheinway
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Cheng, Yung-Sheng
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Chen, Liang-Chien
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Hsu, Hung-Jui
Current bathymetric models for the South China Sea (SCS) are largely based on predicted depths from gravity and sparse single-beam echo-sounder measurements. Such models lack high-resolution coastlines and shallow water bottom features around atolls and islands. This study refines the gravity field of the SCS using sea surface heights from measurements of satellite altimeter Geosat/GM, ERS-1/GM, Jason-1/GM and the original Cryosat-2. A new one-minute gravity anomaly grid is determined. The modeled gravity anomalies show a 6-mgal RMS discrepancy with shipborne measurements in shallow waters. An altimeter-only bathymetric model is derived from the new gravity grid by the gravity-geological method that uses the latest global and regional models of the ocean depth and marine gravity as a priori knowledge. The new model outperforms current SCS bathymetric models and is accurate to 100 m, based on comparison with multi-beam depth measurements. Optical images from IKONOS-2, QuickBird-2, GeoEye-1, WorldView-1-2 and -3, are rectified and digitized to derive the zero (coastline) and 20-m depth contours (reef lines) around 44 atolls, which are integrated with the altimeter-only depths, giving significantly improved accuracies and spatial resolutions in modeled depths. The improvement percentages of coastlines by the satellite imagery range from 50% to 97% at 41 of the 44 atolls. We establish a webpage for free access to the optical and depth images, and the depth and gravity grids. We will continue to update satellite images, altimeter-derived gravity grids and bathymetric models over major atolls of the SCS. (C) 2016 Elsevier Inc. All rights reserved.
Preliminary Analysis of Lake Level and Water Storage Changes over Lakes Baikal and Balkhash from Satellite Altimetry and Gravimetry
(2011-04-01)
Hwang, Cheinway
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Kao, Yu-Chi
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Tangdamrongsub, Natthachet
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土木工程學系
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Department of Civil Engineering
Lakes Baikal and Balkhash are two of the world's major lakes affecting fresh water supplies in their catchments. Measurements from satellite altimetry (TOPEX/Poseidon, Jason-1 and -2), satellite gravimetry (GRACE) and a hydrological model (LDAS) are used to see the relationship between lake level change (LLC) and water storage change in these two lakes. At Lake Baikal, the average rate of LLC is negative for 1992 - 1998 and positive for 1998 - 2007, and the reversal of the LLC trend concurs with that of the temperature trend during the 1997 - 1998 El Nino. The rate of gravity change ranges from -0.5 to 0.5 mu gal yr(-1) with a low over the Tian Shan and a high over western Lake Baikal. Due to the climates over the two lakes, the phases of the annual gravity changes differ by up to 100 days. Using the rates of LLC and gravity changes, the ratios between the mass changes of the lake and its catchment over Lakes Baikal and Balkhash are estimated to 0.6 and 0.3, respectively. The result may help to establish water balance models over these two lakes.
Water storage loss in central and south Asia from GRACE satellite gravity: correlations with climate data
(2011-11-01)
Tangdamrongsub, Natthachet
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Hwang, Cheinway
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Kao, Yu-Chi
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土木工程學系
;
Department of Civil Engineering
Recent decrease of water supply in central Asia and south Asia affects billions of people here. By filtering the errors at higher frequency components and correcting for the contaminated components, we enhance the monthly GRACE gravity fields to improve the determination of change in equivalent water height (EWH). The water storage changes from GRACE and the GLDAS hydrology model all show decreasing trends in this region. At the annual and inter-annual time scales, significant correlations between the variations in EWH and the variations in temperature, precipitation and snow equivalent height are found, especially at high altitude stations, suggesting that climate change is the driving factor for the water depletion in central Asia and south Asia.