ON THE PROPERTIES OFε(≥0) OPTIMAL POLICIES IN DISCOUNTED UNBOUNDED RETURN MODEL

This paper investigates the properties of ε(≥0) optimal policies in the model of [2].It is shownthat,if π~*=(π_0~*,π_1~*,…,π_n~*,π_(n+1)~*,…)is a β-discounted optimal policy,then(π_0~*,π_1~*,…,π_n~*)~∞ for alln≥0 is also a β-discounted optimal policy.Under some condition we prove that stochastic stationarypolicy π_n~(*∞)corresponding to the decision rule π_n~* is also optimal for the same discounting factor β.Wehave also shown that for each β-optimal stochastic stationary policy π_0~(*∞),π_0~(*∞) can be decomposed intoseveral decision rules to which the corresponding stationary policies are also β-optimal separately;and conversely,a proper convex combination of these decision rules is identified with the former π_0~*.We have further proved that for any (ε,β)-optimal policy,say π~*=(π_0~*,π_1~*,…,π_n~*,π_(n+1)~*,…),(π_0~*,π_1~*,…,π_(n-1)~*)∞ is ((1-β~n)~(-1)ε,β)optimal for n>0.At the end of this paper we mention that the resultsabout convex combinations and de     

Effect of SiN:H_x passivation layer on the reverse gate leakage current in GaN HEMTs

This paper concentrates on the impact of SiN passivation layer deposited by plasma-enhanced chemical vapor deposition(PECVD) on the Schottky characteristics in GaN high electron mobility transistors(HEMTs). Three types of SiN layers with different deposition conditions were deposited on GaN HEMTs. Atomic force microscope(AFM), capacitance-voltage(C-V), and Fourier transform infrared(FTIR) measurement were used to analyze the surface morphology, the electrical characterization, and the chemical bonding of SiN thin films, respectively. The better surface morphology was achieved from the device with lower gate leakage current. The fixed positive charge Q_f was extracted from C-V curves of Al/SiN/Si structures and quite different density of trap states(in the order of magnitude of 1011-1012 cm~(-2)) was observed.It was found that the least trap states were in accordance with the lowest gate leakage current. Furthermore, the chemical bonds and the %H in Si-H and N-H were figured from FTIR measurement, demonstrating an increase in the density of Q_f with the increasing %H in N-H. It reveals that the effect of SiN passivation can be improved in GaN-based HEMTs by modulating %H in Si-H and N-H, thus achieving a better Schottky characteristics.     

无界报酬折扣模型最优策略结构

本文讨论Harrison意义下无界报酬折扣模型的最优策略的性质与结构,它们实际上是可数状态空间与行动集上和一般状态与行动空间上两种有界折扣模型的结果,在这种无界折扣模型上的实现.主要结果如下.定理1 若