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Physical models and grey system models (GSMs) are commonly used to evaluate and predict physical behavior. A physical model avoids the incorrect trend series of a GSM, whereas a GSM avoids the assumptions and uncertainty of a physical model. A technique that combines the results of physical models and GSMs would make prediction more reasonable and reliable. This study proposes a fusion method for combining two trend series, calculated using two one-dimensional models, respectively, that uses a slope criterion and a distance weighting factor in the temporal and spatial domains. The independent one-dimensional evaluations are upgraded to a spatially and temporally connected two-dimensional distribution. The proposed technique was applied to a subsidence problem in Jhuoshuei River Alluvial Fan, Taiwan. The fusion results show dramatic decreases of subsidence quantity and rate compared to those estimated by the GSM. The subsidence behavior estimated using the proposed method is physically reasonable due to a convergent trend of subsidence under the assumption of constant discharge of groundwater. The technique proposed in this study can be used in fields that require a combination of two trend series from physical and nonphysical models. [ABSTRACT FROM AUTHOR]

This paper proposes a quadratic differential and integration (QDI) technique for the design of V2 control buck converters with small equivalent series resistance (ESR) of the output capacitor. The QDI technique, which eliminates the use of large ESR in the V2 control structure, achieves the fast transient response with the small output voltage variation in transient period. Besides, the precise sensing signal is derived from the QDI circuit without the unwilling ESR-related distortion. Moreover, the loop analysis demonstrates that the proposed QDI circuit and the proportional and integral compensator can generate the compensation zero pair to stabilize the system. Experimental results show that the output voltage has small voltage ripple opposite to the conventional V2 control. In load transient period, the overshoot/undershoot voltage is smaller than 40 mV when output voltage is 2 V, and the transient recovery time inheriting the advantage of V2 control is shorter than 9 μs with the load step from 100 to 400 mA and vice versa. The highest full chip power conversion efficiency is about 93%. [ABSTRACT FROM AUTHOR]