A suboptimal minimum mean-squared error estimation （MMSE） is proposed for a dispersive wireless channel in the absence of its .orrelation matrix for multipleinput multiple-output ort,ogonal frequency division mult...A suboptimal minimum mean-squared error estimation （MMSE） is proposed for a dispersive wireless channel in the absence of its .orrelation matrix for multipleinput multiple-output ort,ogonal frequency division multiplexing （MIMO - OFDM） transmission. It utilizes a fast subspace approximation tracking to separate signal subspace with a limited set of channel estimates. The subspace rank is adjusted by pre-set thresholds in different signal-to-noise ratios （SNRs）. The performance comparison among the proposed algorithm, least square based, and the optimal MMSE estimation is shown by numerical simulation under a spatially correlated multi-tap channel scenario. It demonstrates that the approach has better normalized mean square error than recursive least square estimation and yields 3 dB gain over the latter.展开更多
Based on the theory of geomechanics and using geologic analytical methods,analyed the fault characteristics, mechanical properties, displacement mode, tectonic system, structural pattern, activity mode of stress, tect...Based on the theory of geomechanics and using geologic analytical methods,analyed the fault characteristics, mechanical properties, displacement mode, tectonic system, structural pattern, activity mode of stress, tectonic activity, and tectonic evolution ofthe area of the Xiamen submarine tunnel, the strike NWW 295^(。), which is the main unfavorable geological structure that affects the safety of the tunnel construction; the macrogeological prediction concludes that weathered troughs and groundwater-rich zonesformed by its larger-scale fault fracture zones are the main unfavorable geological bodiesprovides a basis for preventing the geo-logical hazards in the tunnel construction.展开更多
Traditional CMOS technology faces some fundamental physical limitations. Therefore, it has become very important for the integrated circuit industry to continue to develop modem devices and new design methods. The thr...Traditional CMOS technology faces some fundamental physical limitations. Therefore, it has become very important for the integrated circuit industry to continue to develop modem devices and new design methods. The threshold logic gate has attracted much attention because of its powerful logic function. The resonant tunneling diode （RTD） is well suited for imple- menting the threshold logic gate because of its high-speed switching capability, negative differential resistance （NDR） charac- teristic, and functional versatility. In this paper, based on the Reed-Muller （RM） algebraic system, a novel method is proposed to convert three-variable non-threshold functions to the XOR of multiple threshold functions, which is simple and has a program- mable implementation. With this approach, all three-variable non-threshold functions can be presented by the XOR of two threshold functions, except for two special functions. On this basis, a novel three-variable universal logic gate （ULG3） is proposed, composed of two RTD-based universal threshold logic gates （UTLG） and an RTD-based three-variable XOR gate （XOR3）. The ULG3 has a simple structure, and a simple method is presented to implement all three-variable functions using one ULG3. Thus, the proposed ULG3 provides a new efficient universal logic gate to implement RTD-based arbitrary n-variable functions.展开更多
基金National Natural Science Foundation of China (No.60572157)International Cooperation Foundation of Shanghai Jiaotong University,China (No.2008DFA11950)
文摘A suboptimal minimum mean-squared error estimation （MMSE） is proposed for a dispersive wireless channel in the absence of its .orrelation matrix for multipleinput multiple-output ort,ogonal frequency division multiplexing （MIMO - OFDM） transmission. It utilizes a fast subspace approximation tracking to separate signal subspace with a limited set of channel estimates. The subspace rank is adjusted by pre-set thresholds in different signal-to-noise ratios （SNRs）. The performance comparison among the proposed algorithm, least square based, and the optimal MMSE estimation is shown by numerical simulation under a spatially correlated multi-tap channel scenario. It demonstrates that the approach has better normalized mean square error than recursive least square estimation and yields 3 dB gain over the latter.
基金Supported by the National Natural Science Foundation of China(10702072)the Education Department of Hebei Province (Z2006428)Doctoral Foundation of Hebei Normal University of Science & Technology
文摘Based on the theory of geomechanics and using geologic analytical methods,analyed the fault characteristics, mechanical properties, displacement mode, tectonic system, structural pattern, activity mode of stress, tectonic activity, and tectonic evolution ofthe area of the Xiamen submarine tunnel, the strike NWW 295^(。), which is the main unfavorable geological structure that affects the safety of the tunnel construction; the macrogeological prediction concludes that weathered troughs and groundwater-rich zonesformed by its larger-scale fault fracture zones are the main unfavorable geological bodiesprovides a basis for preventing the geo-logical hazards in the tunnel construction.
基金supported by the National Natural Science Foundation of China(Nos.61271124 and 61471314)the Zhejiang Provincial Natural Science Foundation of China(Nos.LY13F010001 and LY15F010011)
文摘Traditional CMOS technology faces some fundamental physical limitations. Therefore, it has become very important for the integrated circuit industry to continue to develop modem devices and new design methods. The threshold logic gate has attracted much attention because of its powerful logic function. The resonant tunneling diode （RTD） is well suited for imple- menting the threshold logic gate because of its high-speed switching capability, negative differential resistance （NDR） charac- teristic, and functional versatility. In this paper, based on the Reed-Muller （RM） algebraic system, a novel method is proposed to convert three-variable non-threshold functions to the XOR of multiple threshold functions, which is simple and has a program- mable implementation. With this approach, all three-variable non-threshold functions can be presented by the XOR of two threshold functions, except for two special functions. On this basis, a novel three-variable universal logic gate （ULG3） is proposed, composed of two RTD-based universal threshold logic gates （UTLG） and an RTD-based three-variable XOR gate （XOR3）. The ULG3 has a simple structure, and a simple method is presented to implement all three-variable functions using one ULG3. Thus, the proposed ULG3 provides a new efficient universal logic gate to implement RTD-based arbitrary n-variable functions.
