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51.
The most crucial issue of quantum cryptography protocols is its security. There exists many ways to attack the quantum communication process. In this paper, we present a model checking method for modeling the eavesdropping in quantum information protocols. So when the security properties of a certain protocol are needed to be verified, we can directly use the models which are already built. Here we adopt the probabilistic model checking tool—PRISM to model these attack methods. The verification results show that the detection rate of eavesdropping is approximately close to 1 when enough photons are transmitted.  相似文献   
52.
A new method for processing low-light-level moving image sequence is proposed, in which (1) a novel algorithm based on difference processing has been firstly developed to determine the motion parameters of moving image sequence, (2) the spatial relativity of the frames within moving image sequence can be then well established after frame shifting according to motion parameters obtained above, (3) finally, frame integration method can be applied to each processed frame, thereby increasing the signal-to-noise ratio of low-light-level moving image sequence. Experiments have been carried out to verify the validity of the proposed method, which show that the parameters obtained by the developed algorithm coincide well with the actual values, and the SNRs of the moving image sequences were effectively increased with the proposed method, indicating that the method offers significant advantages in the enhancement of low-light-level moving image sequence.  相似文献   
53.
推导了准单色光波情况下高斯脉冲伪随机序列偏振度的简洁数学表达式.理论分析结果表明,偏振度与差分群延迟之间的关系与线路啁啾和光纤色散无关,并且此关系可以由光信号频谱半宽度Δω和分光比γ唯一确定.用10 Gbit/s 7级m序列归零码进行的实验表明:实验结果与理论推导基本一致,从而验证了推导公式的正确性.  相似文献   
54.
We report on an improvement in the crystal quality of GaN film with an Ino.17Alo.83N interlayer grown by pulsed metal-organic chemical vapor deposition, which is in-plane lattice-matched to GaN films. The indium composition of about 17% and the reductions of both screw and edge threading dislocations (TDs) in GaN film with the InA1N interlayer are estimated by high resolution X-ray diffraction. Transmission electron microscopy (TEM) measurements are employed to understand the mechanism of reduction in TD density. Raman and photoluminescence measurements indicate that the InA1N interlayer can improve the crystal quality of GaN film, and verify that there is no additional residual stress induced into the GaN film with InA1N interlayer. Atomic force microscopy measurement shows that the InA1N interlayer brings in a smooth surface morphology of GaN film. All the results show that the insertion of the InA1N interlayer is a convenient method to achieve excellent crystal quality in GaN epitaxy.  相似文献   
55.
With the purpose of uniform gain coefficient along the axial direction in the core of gain guided and index anti-guided fiber, a new kind of side-pump scheme by wrapping particularly treated fibers around the central GGIAG fiber is reported in this paper. According to leakage mode analysis on wrapped fiber and numerical simulation on this pumping structure having ytterbium doped central fiber and conventional wrapped side fiber, we find this kind of pump scheme can improve the uniformity of gain coefficient along the fiber direction, and also, it can support multi channels of pumping sources by adding more side fibers to improve the total effective incident pumping power.  相似文献   
56.
5种丹参主要成分及微结构的检测及综合表征   总被引:1,自引:0,他引:1  
利用X射线荧光(XRF)、粉末X射线衍射(PXRD)和傅里叶变换红外光谱(FTIR)分析技术,对安国栽培的5个不同种质丹参主要成分及微结构检测,对各样品中多种元素种类及含量、晶体及非晶体成分以一套综合特征图的方式对其表征;该谱将同种属不同种质丹参中的共有成分和细微差异之处给与直观地描述。3种技术共有制样简单,测定速度快,再现性和客观性好的特点;可用于药材优良品种的选育、中药材GAP种植条件的指导、药材产地特征、主要成分及微结构的检测及表征、质量稳定性的控制及真伪鉴别。  相似文献   
57.
The applicability of liquid chromatography-mass spectrometry (LC/MS) is often limited by throughput. The sharing of a mass spectrometer with multiple LCs significantly improves throughput; however, the reported systems have not been designed to fully utilize the MS duty cycle, and as a result to achieve maximum throughput. To fully utilize the mass spectrometer, the number of LC units that a MS will need to recruit is application dependent and could be significantly larger than the current commercial or published implementations. For the example of a single analyte, the number may approach the peak capacity to a first degree approximation. Here, the construction of a MS system that flexibly recruits any number of LC units demanded by the application is discussed, followed by the method to port a previously developed LC/MS method to the system to fully utilize a mass spectrometer. To demonstrate the performance and operation, a prototypical MS system of eight LC units was constructed. When 1-min chromatographic separations were performed in parallel on the eight LCs of the system, the average LC/MS analysis time per sample was 10.5 s when applied to the analysis of samples in 384-well plate format. This system has been successfully used to conduct large-volume biochemical assays with the analysis of a variety of molecular entities in support of drug discovery efforts. Allowing the recruitment of the number of LC units appropriate for a given application, this system has the potential to be a plug-and-play system to fully utilize a mass spectrometer. Copyright ? 2012 John Wiley & Sons, Ltd.  相似文献   
58.
灯盏花和多舌飞蓬为菊科飞蓬属植物,由于其形态上非常相似,因此在藏医药均被叫着"美多罗米"用于清热解毒、瘟病时疫.然而,它们在现代监床应用方面存在明显的差异.为了能简便快速的鉴别灯盏花和多舌飞蓬,借助于傅里叶变换红外光谱分析,采用主成分分析法(PCA)对来自13个不同产地的灯盏花和多舌飞蓬样品在植化组成上的相似性进行了聚类分析.比较了灯盏花和多舌飞蓬之间的差异程度,结果表明FTIR结合主成分分析在反映同属不同种及不同产地的同种植物化学组成差异程度上具有重要意义.所建立的方法可以快速、简便、直观地对灯盏花和多舌飞蓬进行聚类分析和质量鉴别,也可以为其他中药材和民族药材的鉴别研究提供参考.  相似文献   
59.
常昊  杨莉  王丽君  吴健  段文晖 《物理》2005,34(12):887-888
文章报道了最近对氢吸附导致β-SiC(001)-32表面金属化的研究结果.提出了β-SiC(001)-32表面金属化的一种新机制:通过形成氢桥键(Si-H-Si 复合结构)形成表面n型掺杂.该复合结构通过氢桥键增强了沟槽底部的弱结合的Si-Si二聚体,并向体系的导带提供电子.  相似文献   
60.
A topographic target light scattering-differential optical absorption spectroscopy(ToTaL-DOAS) system is developed for measuring average concentrations along a known optical path and studying surface-near distributions of atmospheric trace gases.The telescope of the ToTaL-DOAS system points to targets which are located at known distances from the measurement device and illuminated by sunlight.Average concentrations with high spatial resolution can be retrieved by receiving sunlight reflected from the targets.A filed measurement of NO2 concentration is performed with the ToTaL-DOAS system in Shijiazhuang in the autumn of 2011.The measurement data are compared with concentrations measured by the point monitoring technique at the same site.The results show that the ToTaL-DOAS system is sensitive to the variation of NO2 concentrations along the optical path.  相似文献   
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