Energy-Momentum Pseudo-Tensor of Relic Gravitational Wave of Both the Polarized States

Unlike usual celestial gravitational waves, the relic gravitational waves （RGWs） form random signals in curved spacetime background. We calculate the energy-momentum pseudo-tensor of a certain component of the RGWs propagating along arbitrary directions in Cartesian coordinates. It is found that the energy density of RGWs is positive definitely, and the momentum density components have reasonable behaviour. Such results may provide a theoretical basis for the detection of RGWs.     

变参数波振器中小信号增益公式

利用微扰展开技术推导出变参数波振器的小信号增益两个近似求积表达式并将其计算结果与数值模拟结果进行了比较,二者吻合很好。利用近似解析式对小信号增益进行了初步探讨,得到了电子入射能量可低于初始谐振能,能散度允许范围受波振器设计影响以及降低锥度改变率可提高小信号增益等新结论。     

多量子核磁共振的直接观测

本文用异核弱耦合体系AX_n(n=1,2,3)证明,多量子相干性(MQC)在弱连续波(CW)辐射场的微扰下可以实时地显示各阶多量子(MQ)跃迁.文中讨论了CW频率偏置及辐射场强对所观测的MQ跃迁的影响,指出这种单次扫描的MQNMR方法灵敏度高,谱易于辨认,只需要一维Fourier变换,因此具有应用前景.文中还对CW辐照产生的Raman效应作出解释.     

Detecting emboli from Doppler ultrasound signals with the wavelet packet analysis method

A Doppler ultrasound analysis method based on wavelet package transform was proposed for embolic detection. The embolic Doppler signal was firstly decomposed using the wavelet packet. Then the sensitive characteristics were calculated from each sub-band signal and used in the emboli classification. This method was applied to analyze 300 cases simulated and 163 cases clinical Doppler signals. The minimum error ratio of embolic detection using this method was 13 percents lower than that using the traditional spectrogram analysis method.It was shown that this method overcame the limit between the time and frequency resolution in the short time Fourier transform, improved the accuracy of embolic detection greatly and extracted more reliable parameters for the clinical diagnosis.     

An approach to the detection of underwater remote target

An approach to the detection of underwater remote target by estimating its backscattering coefficient is presented. The key to this approach is that the echo signal is represented in state-variable model and the back-scattering coefficients of target are contained in dynamic noise of this model, thus underwater target can be detected by estimating this dynamic noise, i.e., deconvolving this model. When all noise statistics are a priori known, an optimum deconvolution algorithm based on the optimum state filter is derived, or else, an adaptive deconvolution algorithm based on the adaptive state filter of alternatively estimating the vector state and the noise statistics is developed. In the final simulation test, an echo signal with SNR equal to -6.1 dB is proceeded using the aforementioned two deconvolution algorithms, respectively, and the results demonstrate good performance of the approach.     

Cascade Grating Structure for Increasing the Channel Number on Holographic Demultiplexer

The expansion capability of the channel number in the optical demultiplexer using two cascaded photopolymer volume gratings is reported. It could be accomplished by designing of two gratings with different spectral range. As a result of the experiment, a 0.4-nm-spaced 130-channel demultiplexer with the channel uniformity of 3.5 dB, the 3 riB-bandwidth of 0.12nm, and the channel crosstalk of-20 dB is experimentally demonstrated.     

弱信号提取中门积分器的设计

介绍动平稳仪中弱信号提取的门积分器的设计。讨论了门脉冲宽度（Ｔｇ）、信号周期（Ｔ）、时间常数（ＲＣ）和信噪比改善的关系，并在实际电路中进行了检测。     

正交信号校正在正常成人血清1H NMR谱的代谢组分析中的滤噪作用评价

观察、比较正交信号校正(OSC)滤噪前后, 用不同的模式识别方法对正常成人血清代谢组¹H NMR谱进行分析的效果, 以探讨NMR代谢组学技术应用于临床研究和疾病早期诊断的可行性. 78例正常成人在采血前按常规要求禁食8 h, 记录血清一维600 MHz氢谱后, 分别采用主成分分析(PCA)、偏最小二乘法-判别分析(PLS-DA)以及簇类的独立软模式法(SIMCA)对氢谱进行模式识别分析. 结果表明: 虽然采血前并无其它诸如饮食、生活方式、生理周期等方面的严格限制, 采用OSC 滤噪后, PLS-DA能够完全区分不同性别的血清氢谱, 其判别能力优于PCA和SIMCA. 而且采用OSC滤噪与文献报道的未经OSC处理的PLS-DA法获得的与性别分类有关的主要NMR积分区段基本相同. 从OSC去除不同数目的隐变量后所致的PLS-DA模型的性能改变可见: OSC去除两个隐变量时, 前两个隐变量的特征值明显比后面的大; 剩余残差为20.82%, 即去除了79.18%的X变量中与反应变量Y不相关的系统变异. 此时PLS-DA计算所得的隐变量个数为1; 而不使用OSC或用OSC去除一个隐变量时, PLS-DA所得的隐变量个数分别为3和2. 作为PLS-DA模型质量的评价指标, R2X表示PLS-DA模型计算所获得的隐变量反映自变量X的变异的百分比, R2Y则表示隐变量反映因变量Y的变异的百分比, Q2 (cum)为交叉验证后PLS-DA模型所获隐变量能够预测X和Y变异的累计百分比. R2X在OSC去除两个隐变量时达到最低值, 表明此时PLS-DA计算模型包含的系统变异最少; R2Y与Q2 (cum)都达到80%以上并趋于稳定, 说明OSC去除两个隐变量时PLS-DA模型的质量优良. 显然, OSC可去除饮食、环境等因素的影响, 降低临床样本的不均一性, 这对于NMR代谢组学技术应用于临床研究至关重要. OSC滤噪去除的隐变量个数应根据剩余残差、去除隐变量的特征值大小、PLS-DA模型计算所得的隐变量个数和反映模型质量的相关指标加以判断.     

群青颜料呈色机理的电子顺磁共振研究

研究了阿富汗青金石矿石、敦煌石窟青金石颜料、合成群青的呈色机理。实验表明三者均有ｇ＝２．０２９峰，前两者多一个ｇ＝２．０４７峰，４００℃时，ｇ＝２．０４７峰变平，６００℃时消失。ｇ＝２．０２９峰随温度升高而增强，８００℃时增强放慢，颜色也随温度变深。在Ｍ０Ｏ３／ＳｉＯ２和Ｍ０Ｏ３／Ａｌ２Ｏ３表面上，Ｓ２＾－的ＥＰＲ有ｇ１＝２．０４７，ｇ２＝２．２０８，ｇ３＝１．９９８三个分量。因此，群青、青金石和