基于接收信号强度指示(Received Signal Strength Index,RSSI)的测距技术因其低成本及低复杂度被广泛用于无线传感网络(WSN)定位技术中。由于RSSI值易受环境的影响,即使在同一位置采集到的RSSI值也会出现波动、突变,从而导致测距结果误...基于接收信号强度指示(Received Signal Strength Index,RSSI)的测距技术因其低成本及低复杂度被广泛用于无线传感网络(WSN)定位技术中。由于RSSI值易受环境的影响,即使在同一位置采集到的RSSI值也会出现波动、突变,从而导致测距结果误差较大。在分析RSSI测距原理和当前常见的滤波算法的基础上,通过实验比较单一滤波的效果,综合单一滤波的优势,提出了一种基于狄克逊检验法滤波、中位值滤波及高斯滤波的混合滤波算法。实验首先利用线性回归算法优化RSSI测距模型的参数,再通过混合滤波过滤异常RSSI值来获得最优值,以实现准确测距。实验结果显示,与单一的滤波算法相比,混合滤波算法能明显减小RSSI值的波动,更为有效地剔除异常RSSI值,且滤波后的RSSI值更接近理想值,测距误差更小,证明了混合滤波算法是有效且可行的。展开更多
Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 , Fe55 Cu2 Cr12 Mo10 B6 C13 Y2 and Fe55 Nb2 Cr12 Mo10 B6 C13 Y2 alloys with diameter of 4 mm were produced by copper mold casting. The effect of alloying additions （Ni, Cu or Nb） on corr...Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 , Fe55 Cu2 Cr12 Mo10 B6 C13 Y2 and Fe55 Nb2 Cr12 Mo10 B6 C13 Y2 alloys with diameter of 4 mm were produced by copper mold casting. The effect of alloying additions （Ni, Cu or Nb） on corrosion resistance of Fe55 Nb2 Cr12 Mo10B6 C13 Y2, Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 and Fe55 Cu2 Cr12 Mo10 B6 C13 Y2 alloys was studied by polarization curves and electrochemical impedance spectroscopy （EIS）. The results show that Fe55 Ni2 Cr12 Mo10 B6C13 Y2 and Fe55 Cu2 Crl2 MOl0 B6 C13 Y2 alloys can be cast to form bulk metallic glasses. Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 and Fe55 Cu2 Cr12 Mo10 86 C13 Y2 amorphous alloys with passive potential about 1 500 mV exhibit good corrosion resistance in NaCI solution of 5% and 1 mol/L HC1 solution. The passive current density of the alloy with Ni addition is lower than that of other alloys. EIS results only show one impedance element. Amorphous alloy Fe55 Ni2 Cr12 Mo10 B6C13 Y2 with larger charge transfer reaction resistance indicates good corrosion resistance.展开更多
Fe-Co-B-Si-Nb-C glassy alloy with the addition of C was prepared by arc melting and copper suck-casting. The thermodynamics and soft magnetic properties were investigated. The casted amorphous alloys were heat-treated...Fe-Co-B-Si-Nb-C glassy alloy with the addition of C was prepared by arc melting and copper suck-casting. The thermodynamics and soft magnetic properties were investigated. The casted amorphous alloys were heat-treated at different temperatures. The differential scanning calorimeter （DSC） results and thermal expansion show complete thermodynamics of crystallization. Its magnetostriction properties were studied by capacitance method. Saturation magnetostriction increases to 38×10^-6. The amorphous alloy exhibits good soft magnetic properties with low coercivity and high saturation magnetic induction. The results show that minor addition of C is beneficial to enhance the saturation magnetostriction λs, and do not deteriorate the ability of forming amorphous.展开更多
文摘基于接收信号强度指示(Received Signal Strength Index,RSSI)的测距技术因其低成本及低复杂度被广泛用于无线传感网络(WSN)定位技术中。由于RSSI值易受环境的影响,即使在同一位置采集到的RSSI值也会出现波动、突变,从而导致测距结果误差较大。在分析RSSI测距原理和当前常见的滤波算法的基础上,通过实验比较单一滤波的效果,综合单一滤波的优势,提出了一种基于狄克逊检验法滤波、中位值滤波及高斯滤波的混合滤波算法。实验首先利用线性回归算法优化RSSI测距模型的参数,再通过混合滤波过滤异常RSSI值来获得最优值,以实现准确测距。实验结果显示,与单一的滤波算法相比,混合滤波算法能明显减小RSSI值的波动,更为有效地剔除异常RSSI值,且滤波后的RSSI值更接近理想值,测距误差更小,证明了混合滤波算法是有效且可行的。
基金Item Sponsored by Major Project Foundation of Beijing of China (D405003000021)
文摘Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 , Fe55 Cu2 Cr12 Mo10 B6 C13 Y2 and Fe55 Nb2 Cr12 Mo10 B6 C13 Y2 alloys with diameter of 4 mm were produced by copper mold casting. The effect of alloying additions （Ni, Cu or Nb） on corrosion resistance of Fe55 Nb2 Cr12 Mo10B6 C13 Y2, Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 and Fe55 Cu2 Cr12 Mo10 B6 C13 Y2 alloys was studied by polarization curves and electrochemical impedance spectroscopy （EIS）. The results show that Fe55 Ni2 Cr12 Mo10 B6C13 Y2 and Fe55 Cu2 Crl2 MOl0 B6 C13 Y2 alloys can be cast to form bulk metallic glasses. Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 and Fe55 Cu2 Cr12 Mo10 86 C13 Y2 amorphous alloys with passive potential about 1 500 mV exhibit good corrosion resistance in NaCI solution of 5% and 1 mol/L HC1 solution. The passive current density of the alloy with Ni addition is lower than that of other alloys. EIS results only show one impedance element. Amorphous alloy Fe55 Ni2 Cr12 Mo10 B6C13 Y2 with larger charge transfer reaction resistance indicates good corrosion resistance.
基金Item Sponsored by National High-Tech Research and Development Program(863 Program) of China(2007AA03Z102)National Natural Science Foundation of China(51071050)
文摘Fe-Co-B-Si-Nb-C glassy alloy with the addition of C was prepared by arc melting and copper suck-casting. The thermodynamics and soft magnetic properties were investigated. The casted amorphous alloys were heat-treated at different temperatures. The differential scanning calorimeter （DSC） results and thermal expansion show complete thermodynamics of crystallization. Its magnetostriction properties were studied by capacitance method. Saturation magnetostriction increases to 38×10^-6. The amorphous alloy exhibits good soft magnetic properties with low coercivity and high saturation magnetic induction. The results show that minor addition of C is beneficial to enhance the saturation magnetostriction λs, and do not deteriorate the ability of forming amorphous.
