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131.
Hyeong Soo Chang 《Automatic Control, IEEE Transactions on》2005,50(9):1413-1418
This note considers finite-step approximations for solving an infinite-horizon controlled Markov set-chain problem with finite state and action spaces. We develop a value-iteration type algorithm based on the optimality equation developed by Kurano et al. and analyze an error bound relative to the optimal value that satisfies the optimality equation from the successive approximation. We further analyze an error bound of the approximate control policy defined from a finite-step approximate value by applying the value-iteration type algorithm. 相似文献
132.
Hao Yin Chuang Lin Berton Sebastien Bo Li Geyong Min 《International Journal of Communication Systems》2005,18(8):711-729
Fast and accurate methods for predicting traffic properties and trend are essential for dynamic network resource management and congestion control. With the aim of performing online and feasible prediction of network traffic, this paper proposes a novel time series model, named adaptive autoregressive (AAR). This model is built upon an adaptive memory‐shortening technique and an adaptive‐order selection method originally developed by this study. Compared to the conventional one‐step ahead prediction using traditional Box–Jenkins time series models (e.g. AR, MA, ARMA, ARIMA and ARFIMA), performance results obtained from actual Internet traffic traces have demonstrated that the proposed AAR model is able to support online prediction of dynamic network traffic with reasonable accuracy and relatively low computation complexity. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
133.
Jui-Chieh Chiu Chieh-Pin Chang Mau-Phon Houng Yeong-Her Wang 《Microwave and Wireless Components Letters, IEEE》2006,16(1):19-21
A novel configuration of balanced frequency InGaAs pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuit (MMIC) tripler is proposed. A resonant LC filter is used to eliminate the fundamental frequency and a phase delay line is employed to suppress the second harmonic. The separation of the independent phase shifters makes the tripler more compact and flexible. The conversion loss of the tripler operating from 12 to 36GHz is less than 9.4dB at 9-dBm input power. As compared to the third-harmonic frequency, the fundamental frequency is suppressed more than 21.4dB while for the second harmonic is more than 22.3dB at 36GHz. 相似文献
134.
Trajectory design considering derivative of jerk for head-positioning of disk drive system with mechanical vibration 总被引:1,自引:0,他引:1
In this paper, we propose a novel design method of target trajectory for high-speed and high-precision head positioning of a hard disk drive (HDD) system. To realize smooth acceleration and deceleration, the derivative of jerk is considered not to activate any mechanical vibrations. We applied the well-known optimal control theory to fix the initial and terminal conditions. Moreover, we show that various performances can be improved by introducing time-varying weighting coefficients. Some experimental results using a 2.5-in HDD are shown to verify the effectiveness of the proposed method. 相似文献
135.
上海同步辐射装置(SSRF)储存环铝合金超高真空室已研制成功,该机加真空室的尺寸大、尺寸精度、形位公差及粗糙度要求极高,不同于常规的大型超高真空室。在预研件加工中,成功地解决了一系列问题,如光洁度提高困难,加工成型后变形大;加工尺寸和精度受环境温度影响较大等。本文详细阐述了储存环真空室材料和热处理状态的选择依据,为了保证尺寸精度和形位公差所采取的工艺措施,分析了粗糙度的形成机理和影响因素,从刀具材料、几何角度、切削参数、冷却液选型等多方面提出了解决办法。 相似文献
136.
137.
138.
个人剂量仪两种电源电路设计的比较 总被引:1,自引:0,他引:1
个人剂量仪器一般要求采用电池供电,并且希望电池使用的时间越长越好,随着电池电压的降低,仪器的一些性能也会下降,合理的电源设计会延长电池的使用寿命,也能提高仪器性能,介绍了电池直接供电和采用电源芯片转换供电两种方法,并结合个人剂量仪主要进行了仪器功耗,电池使用寿命的比较,也进行了仪器其它性能,仪器成本,体积等方面的比较,通过比较结果,可根据仪器的实际要求来选择电源电路设计的方法。 相似文献
139.
We study theoretically the effect of the quasiparticle scattering in field-induced spin density waves (FISDW) in Bechgaard salts in a high magnetic field. The effects of scattering are introduced by a random impurity model similar to the one used by Zittartz in his analysis of the charge density wave. Within the single-gap approximation and weak impurity scattering, we find that the FISDW with normal impurities is similar to a superconductor with magnetic impurities. From this analogy the thermodynamics as well as the electronic thermal conductivity and the sound attenuation coefficient of the FISDW are obtained.On leave of absence from Nankai University, China. 相似文献
140.
J.-S. LiuJ.-H. Chuang 《Pattern recognition》2002,35(1):155-167
For choosing specific cross-ratios as 2D projective coordinates in various computer vision applications, a reasonable error analysis model is usually required. This investigation adopts the assumption of normal distribution for positioning errors of point features in an image to formulate the error variances of cross-ratios. Based on a geometry-based error analysis, a straightforward way of identifying the cross-ratios with minimum error variances is proposed. Simulation results show that the proposed approach, as well as a further simplified alternative, yield much better estimations of minimum error variances in terms of accuracy, cost, and stability compared with some other methods, e.g., the one based on the rule given by Georis et al. (IEEE Trans. Pattern Anal. Mach. Intell. 20 (4) (1998) 366). Some causes of the performance differences in the estimations are explained using a special configuration of point features. 相似文献