AUTONOMOUS NAVIGATION OF PROBE BY X-RAY PULSARS BASED ON FADING MEMORY FILTERING

针对扩展Kalman滤波(Extend Kalman Filter, EKF)在处理X射线脉冲星的自主导航定轨问题上易发散的问题,本文提出了基于记忆衰减滤波的抑制发散自主导航算法。在研究了自主导航滤波中误差变化的特征的基础上,从原理上分析了预报误差随迭代次数增加而增大的原因。针对EKF存在的这一缺陷,本文应用记忆衰减滤波控制误差发散,推迟了误差发散的时间并减小了发散的幅值,使得滤波结果稳定于更精确的结果。本文的结论均通过数值计算的方法验证     

催化还原褪色光度法测定粉煤灰中微量铜

在ＰＨ５．０的ＨＡｃ－ＮａＡｃ缓冲休系中,痕量Ｃｕ（Ⅱ）催化抗坏血酸还原偶氮胭脂红Ｂ的褪色反应,褪色程度与Ｃｕ（Ⅱ）量在一定范围内线性相关。建立了测定痕量Ｃｕ（Ⅱ）的光度法,检出限为３．５＊１０＾－１１ｇ／ｍＬ,褪色程度与Ｃｕ（Ⅱ）量在０．０－２．０μｇ／Ｌ范围内符合比耳定律。本法结合Ｎ５３０－Ｎ５１０混合萃取剂萃取分离,测定了粉煤灰中的微量铜。     

结晶紫-苯唑西林的共振瑞利散射光谱及应用

在pH 8.71的Tris-HCI缓冲介质中,结晶紫(CV)与苯唑西林(OXA)结合,使体系的共振瑞利散射(RRS)急剧增强并出现新的RRS光谱,最大共振瑞利散射峰位于380nm处,苯唑西林的浓度在0.08～0.8μg·mL-1范围内与散射强度(△1RRS)成良好的线性关系,据此建立了测定苯唑西林的共振瑞利散射法,检出...     

锂离子电池正极材料LiNi0.5Co0.2Mn0.3O2的合成及其高温容量衰减研究

采用共沉淀-高温固相烧结法合成了富镍型三元复合正极材料LiNi0.5Co0.2Mn0.3O2.恒流充放电测试表明,材料在3.0～4.4 V下0.2C放电容量达到179.2 mAh.g-1,但在55℃下经历100次充放电循环后发生急剧的容量衰减.电化学交流阻抗谱、X射线光电子能谱和原子发射光谱等实验表明,在高温高电压下,电解液与LiNi0.5Co0.2Mn0.3O2电极材料之间的副反应加剧,导致过渡金属原子溶出,该材料局域结构被破坏.同时,电极材料表面还沉积了高阻抗的LiF/MFx层,使得在电极的充放电过程中电荷转移阻抗和Li+扩散阻抗不断增加,以致电池容量急剧衰减.     

I3-共振瑞利散射法测定孔雀石绿及相关效应分析

在弱酸性介质中,孔雀石绿与I3-形成离子缔合物,并进一步聚集成纳米粒子,在λ=468nm下,激发产生强烈的共振瑞利散射。在0.012～0.900μg/L范围内,共振光强度与孔雀石绿的含量成线性关系;线性方程为y=6273.8x 37.1,r=0.9997;本工作研究了反应的适宜条件,建立了共振瑞利法测定孔雀石绿的新方法,方法灵敏度高,检出限为3.6μg/L。在线性范围内,选择低、中、高3组浓度进行精密度实验,RSD分别为2.3%、1.7%、4.2%(n=11)。     

抗多径噪声归一化合并SFH／MFSK系统在短波信道中的性能

分析了具有抗多径措施的噪声归一化合并ＳＦＨ／ＭＦＳＫ接收机在存在部分边带干扰的多径瑞利衰落信道中的性能，着重研究了多径加权因子ω对该系统性能的影响．结果表明，最佳加权困子ω与多径干扰强度、分集重数、调制阶数和信道热噪声有关．对多径合适地加权可明显地降低比特误码率Ｐｂ，在分集和编码相结合时，能使Ｐｂ下降２～３个数量级．     

一种DCSK通信系统的延迟合并接收方案

提出一种多径衰落信道下DCSK通信系统的延迟合并接收方案. 理论分析和仿真结果证实了该方案的误码性能. 结果表明，和原DCSK通信系统相比，使用了延迟合并接收方案的DCSK通信系统误码性能有所提高；不同接收路径延迟对应的误码性能基本相同；各接收路径采用等增益合并方式时误码性能最好；其理论上限随着接收路径数增加而逐渐降低.     

Transmission performance of the SCM label in optical label switching networks

We have investigated the transmission performance of the label signal in the optical double sideband subcarrier multiplexing (DSB-SCM) label switching link and clarified that the degradation of the label signal results from the fiber chromatic dispersion and the incomplete filtering out of the payload carrier. Our theoretical results show that the DSB-SCM label can immune the fading effect, and the degradation mainly results from the crosstalk from the payload and the time shift of the code edge. The deep suppression of the optical carriers at the receiver can eliminate the crosstalk. The time shift of the code edges leads to the eye closure of the label codes and is independent of the code rate, but it does not degrade the label code with a low bit rate greatly, although it is serious for the label with a high bit rate and ultimately limits the transmission distance of the label. The simulation results validate our analysis very well. As we theoretically predict that the single sideband (SSB)-SCM can eliminate the time shift of the code edges and extend the transmission distance of the label signal.     

Tunneling Processes and Anomalous Fading in Natural Feldspars Extracted from Quaternary Deposits

Reasons for a temporal decrease (fading) in the accumulated energy in feldspars used as paleodosimeters are considered. The tunneling processes capable of leading to fading as well as temperature and time dependences of tunnel afterglow have been studied in detail. It is shown that this glow bears no direct relation to the possible tunnel depletion of the dosimetric trapping centers. With a view toward directly observing tunneling from these centers, the temperature dependences (from −200°C to +100°C) of the intensity of the luminescence stimulated in the IR band with λ ≈ 900 nm (of the optically stimulated luminescence (OSL) signal) have been studied in detail. Within the limits of sensitivity of the equipment used, tunneling from the dosimetric centers has not been detected. It has been inferred that in fading of the OSL signal, an essential role can be played by the traps that are depleted at 200°C and have a lifetime of about 2 years at room temperature.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 207–212, March–April, 2005.