基于主成分原理的多元质量控制图的构造

控制图是从事统计质量管理经常使用的重要工具,经过多年的发展和实践,一元质量控制图业已得到普遍推广,可是如何开展多元质量控制仍有许多问题值得探讨。在这篇文章中,我们着重讨论了基于主成分分析的多元质量控制图的构造,并结合从企业现场采集到的数据给出了具体的应用说明。     

Gerdjikov-Ivanov方程的精确解

研究在量子场理论、弱非线性色散水波、非线性光学等领域中出现的Gerdjikov-Ivanov方程.对Gerdjikov-Ivanov方程的研究会导出具有高次非线性项的非线性数学物理方程.选取Liénard方程作为辅助常微分方程,借助于它并根据齐次平衡原则,求解了Gerdjikov-Ivanov方程,得到了该方程的包络孤立波解和包络正弦波解. 关键词： 齐次平衡原则 F展开法 Gerdjikov-Ivanov方程 包络孤立波解     

Security analysis of a spatiotemporal-chaos-based cryptosystem

An S-box modified one-way coupled map lattice is applied as a chaotic cryptograph. The security of the system is evaluated from various attacks currently used, including those based on error function analysis, statistical property analysis, and known-plaintext and chosen-ciphertext analytical computations. It is found that none of the above attacks can be better than the brute force attack of which the cost is exhaustively quantitated by the key number in the key space. Also, the system has fairly fast encryption (decryption) speed, and has extremely long period for finite-precision computer realization of chaos. It is thus argued that this chaotic cryptosystem can be a hopeful candidate for realistic service of secure communications.     

变分原理分析开裂简支箱梁剪力滞效应

变分原理通常应用于箱形截面梁剪力滞效应弹性分析,本文基于换算截面法,运用变分原理推导了预应力混凝土简支箱梁均布荷载作用、钢筋混凝土简支箱梁集中荷载作用的剪力滞系数计算公式,考虑了混凝土开裂对箱梁剪力滞效应的影响,并与试验结果和规范方法进行了对比分析。变分原理分析开裂混凝土箱梁剪力滞效应方法力学概念明确,是其弹性分析适用范围的拓展,亦可推广应用到混凝土连续箱梁开裂后的剪力滞效应分析,具有广阔的应用前景。     

Study of a millimeter-wave squint indirect holographic algorithm suitable for imaging with large field-of-view

In this paper a millimeter-wave （MMW） squint indirect holographic method is presented, which is suitable for imaging with a large field-of-view. The proposed system employs the squint operation mode to remove the background and twin- image interferences, which achieves a similar effect to off-axis holography but leaves out the large-aperture quasi-optical component. The translational scanning manner enables a large field of view and ensures the image uniformity, which is difficult to realize in off-axis holography. In addition, a corresponding imaging algorithm for the presented scheme is developed to reconstruct the image from the recorded hologram. Some imaging results on typical objects, obtained with electromagnetic simulation, demonstrate good performance of the imaging scheme and validate the effectiveness of the image reconstruction algorithm.     

Short Tm3+-doped fiber lasers with watt-level output near 2 μm

High-power operation of diode-pumped fiber lasers at wavelength near 2μm are demonstrated with short length of heavily Tm3 -doped silica glass fibers. With 7-cm long fiber, a laser at near 2 μm is obtained with the threshold of 135 mW, maximum output power of 1.09 W, and slope efficiency of 9.6% with respect to the launched power from a laser diode at 790 nm. The output stability of this fiber laser is within 5%.The dependence of the performance of fiber lasers on the operation temperature and cavity configuration parameters is also investigated.     

Harmonic operation of high gain harmonic generation free electron laser

In high gain harmonic generation (HGHG) free electron laser (FEL), with the right choice of parameters of the modulator undulator, the dispersive section and the seed laser, one may make the spatial bunching of the electron beam density distribution correspond to one of the harmonic frequencies of the radiator radiation, instead of the fundamental frequency of the radiator radiation in conventional HGHG, thus the radiator undulator is in harmonic operation (HO) mode. In this paper, we investigate HO of HGHG FEL.Theoretical analyses with universal method are derived and numerical simulations in ultraviolet and deep ultraviolet spectral regions are given. It shows that the power of the 3rd harmonic radiation in the HO of HGHG may be as high as 18.5% of the fundamental power level. Thus HO of HGHG FEL may obtain short wavelength by using lower beam energy.     

一种冲击分离式颗粒浓度测量装置的设计

为测量大气中颗粒物的粒度浓度,本文在传统的冲击采样原理的基础上设计出冲击式分级装置,并对其进行严格定标;运用消光法原理对分级后的样品进行测量,利用反射镜增大光程提高装置测量灵敏度,实现了对大气中0～5μm、5～20μm、15～40μm三个粒径区间的数量密度和质量浓度的准确测量.     

不同构型(In,Al)GaN合金发光机理的第一性原理研究

基于第一性原理的密度泛函理论,研究了纤锌矿（In,Al）GaN合金的4种构型（均匀、短链、小团簇、团簇-链共存模型）的电子结构和发光微观机理。结果表明,在InGaN合金中,短In-N-链和小In-N团簇都局域电子在价带顶（VBM）态。当小团簇与短链共存时,前者局域电子的能力明显强于后者,是辐射复合发光中心。然而,在AlGaN合金中,电子在VBM态的局域受短Al-N链和小Al-N团簇的影响并不显著。合金微观结构的不同会引起电子局域的改变,从而影响材料的发光性能,并对带隙和弯曲系数有重要影响。     

基于激光雷达观测的大气边界层自动识别局部最优点算法

大气边界层高度是影响近地面大气物理运动的主要因素,同时也是影响地面污染物浓度的一个重要因素。地基激光雷达可以对大气气溶胶的垂直分布进行连续稳定的监测,应用激光雷达技术对大气边界层进行连续观测可以为环境监测与预报提供指导性的动态信息。针对存在残留层以及外来污染物输入情况时边界层高度变化检测的可靠性及计算效率问题,结合梯度法的物理意义与激光雷达时序图的图形图像学特征,提出了一种基于时空邻近度的边界层局部最优点识别算法。以江苏省无锡市新区偏振米散射激光雷达太湖观测站点的气溶胶垂直观测数据为例,通过对2012年底两次污染事件进行观测分析,分别使用梯度法和局部最优点法进行大气边界层高度的自动识别。实验结果表明,在静稳状态和污染混入后的情况下,梯度法与局部最优点识别法的结果较为接近,但梯度法在处理污染混入状态以及存在残留层的情况下误判率较高。基于时空邻近度的局部最优点算法通过对垂直特征值以及水平相关性的控制,有效地消除了在弱信号、噪声信号、低云以及存在残留层和外来污染等情况下导致的计算机误判现象,在减小算法时间复杂度的同时在计算机自动识别结果具有更高的稳定性,弥补了梯度法在自动化运行中的识别精度与计算效率的不足。