基于改进巴氏指标和模型更新的视觉跟踪算法

传统的Mean Shift算法采用巴氏系数度量模型与候选模型之间的统计特征相似性,但是由于背景特征的影响,有时应用巴氏指标进行匹配得到最优解的位置并不一定是目标的实际位置,在跟踪过程中可能导致目标定位出现偏差。该文提出一种改进的巴氏系数相似度指标,指标由于引入了前景/背景置信值,能够有效抑制待匹配区域中背景特征的影响,突出目标特征的权重,与原始的巴氏指标相比,明显提高了目标匹配的准确性。基于改进的巴氏指标,对目标与背景区域双模型相似度系数进行综合分析,合理地判断干扰目标匹配的原因,从而采取相应的模型更新策略。采用4段具有挑战性的视频序列对5种跟踪算法进行了测试,通过定量实验分析可知,文中算法处理1帧视频所需的平均时间为75.76 ms,实时性仅次于原始的Mean Shift跟踪算法,同时跟踪误差在5种跟踪算法中取得了最优结果。实验结果表明,该算法能够有效抑制背景干扰和避免模型漂移,在不同的复杂场景下都具有一定的鲁棒性。     

室温下低温背景红外场景生成方法实验研究

针对高空红外场景模拟的需要,提出了模拟低温背景红外场景的新物理概念和半实物仿真实验装置.将锗单晶制作的初始透明的半导体屏放置于低温系统前端,通过控制其小于禁带宽度的局部辐射系数,在室温下(≥27℃)得到低温背景(≥-30℃)的红外场景.对液氮槽和半导体致冷器生成的冷背景的效果、辐射功率差随写入光功率的变化及低温背景和目标的温度对比度进行了实验测试.实验结果表明,液氮生成的冷背景可达-30℃,半导体致冷器为3℃;在一定范围内增大写入光的功率可以提高半导体屏的转换效率,写入光功率过高会造成辐射功率值的饱和;随着写入光功率的增加,温度对比度也大幅升高.     

基于非参数背景抑制的弱小目标管线法检测

介绍了一种红外图像背景抑制的非参数方法(E_kernel)。提出了一种弱小目标的管线检测算法。E_kernel方法不同于传统的线性或非线性背景预测,它对背景杂波分布的统计特性不敏感,受其影响较小,具有非参数特性。管线检测算法对序列图像做若干相同的顺序处理,采用并行分布式计算,处理时间短。仿真试验表明,该算法能有效地检测出低信噪比红外序列图像中的弱小目标的运动轨迹,具有较高的实时性。     

反相高效液相色谱负峰测定法的研究

用HPLC紫外检测器研究了无紫外吸收化合物的负峰测试法,探讨了负峰测试法的原理。通过对乙酸酯系列的5种样品的分析,确定了负峰测定的基本色谱条件,考察了乙酸酯系列测定的灵敏度、精密度、检出限和线性范围。该法为一些在紫外区无吸收或弱吸收物质的色谱分析提供了一种简捷、方便的手段和色谱机理研究的新方法。同常规的采用正峰测试样品的方法相比较,负峰法应用范围更宽,能使紫外检测器变为一种更通用的检测器。     

Evaluation of uncertainties in X‐ray photoelectron spectroscopy intensities associated with different methods and procedures for background subtraction. I. Spectra for monochromatic Al X‐ray

We report uncertainties in X‐ray photoelectron spectroscopy (XPS) intensities arising from commonly used methods and procedures for subtraction of the spectral background. These uncertainties were determined from a comparison of XPS intensities reported by volunteer analysts from 28 institutions and the corresponding intensities expected for a set of simulated XPS spectra. We analyzed peak intensities from 32 sets of data for a group of 12 spectra that had been simulated for a monochromated Al Kα source. Each reported intensity was compared with an expected intensity for the particular integration limits chosen by each analyst and known from the simulation design. We present ratios of the reported intensities to the expected intensities for the background‐subtraction methods chosen by the analysts. These ratios were close to unity in most cases, as expected, but deviations were found in the results from some analysts, particularly if the main peak was asymmetrical or if shakeup was present. We showed that better results for the Shirley, Tougaard, and linear backgrounds were obtained when analysts determined peak intensities over certain energy ranges or integration limits. We then were able to recommend integration limits that should be a useful guide in the determination of peak intensities for other XPS spectra. The use of relatively narrow integration limits with the Shirley and linear backgrounds, however, will lead to measures of peak intensities that are less than the total intensities. Although these measures may be satisfactory for some quantitative analyses, errors in quantitative XPS analyses can occur if there are changes in XPS lineshapes or shakeup fractions with change of chemical state. The use of curve‐fitting equations to fit an entire spectrum will generally exclude the shakeup contribution to the intensity of the main peak, and no account will be taken of any variation in the shakeup fraction with change of chemical state. Published in 2009 by John Wiley & Sons, Ltd. Certain commercial products are identified to specify the formats in which the test spectra were distributed and the software with which the test spectra were analyzed by participants. This identification does not imply that the products are endorsed or recommended by the National Institute of Standards and Technology, or that they are necessarily the most suitable for the purposes described.     

Evaluation of uncertainties in X‐ray photoelectron spectroscopy intensities associated with different methods and procedures for background subtraction. II. Spectra for unmonochromated Al and Mg X‐rays

We report uncertainties in X‐ray photoelectron spectroscopy (XPS) intensities arising from commonly used methods and procedures for subtraction of the spectral background. These uncertainties were determined from a comparison of XPS intensities reported by volunteer analysts and the corresponding intensities expected for a set of simulated XPS spectra. We analyzed peak intensities from 16 sets of data (submitted from 15 institutions) for a group of 12 spectra that had been simulated for an unmonochromated Al‐Kα source and similar intensities from 20 sets of data (submitted from 17 institutions) that had been simulated for an unmonochromated Mg‐Kα source. Each reported intensity was compared with an expected intensity for the particular integration limits chosen by each analyst and known from the simulation design. We present ratios of the reported intensities to the expected intensities for the background‐subtraction methods chosen by the analysts. These ratios were close to unity in most cases, as expected, but deviations were found in the results from some analysts, particularly if shakeup was present. We showed that better results for the Shirley and Tougaard backgrounds were obtained when analysts determined peak intensities over certain energy ranges or integration limits. We then were able to suggest integration limits that should be a useful guide in the determination of peak intensities for other XPS spectra. The use of relatively narrow integration limits with the Shirley and linear backgrounds, however, will lead to measures of peak intensity that are less than the total intensities. Although these measures may be satisfactory for some quantitative analyses, errors in quantitative XPS analyses can occur if there are changes in XPS lineshapes or shakeup fractions with change of chemical state. The use of curve‐fitting equations to fit an entire spectrum will generally exclude the shakeup contribution to the intensity of the main peak, and any variation in the shakeup fraction with change of chemical state will not be taken into account. Published in 2009 by John Wiley & Sons, Ltd.     

Nonautonomous solitons in the continuous wave background of the variable-coefficient higher-order nonlinear Schro¨dinger equation

We reduce the variable-coefficient higher-order nonlinear Schrdinger equation (VCHNLSE) into the constantcoefficient (CC) one. Based on the reduction transformation and solutions of CCHNLSE, we obtain analytical soliton solutions embedded in the continuous wave background for the VCHNLSE. Then the excitation in advancement and sustainment of soliton arrays, and postponed disappearance and sustainment of the bright soliton embedded in the background are discussed in an exponential system.     

上甸子区域大气本底站NO2柱浓度光谱反演及其变化特征

为了探究京津冀本底浓度地区NO₂这一重要空气污染物的变化特征,采用多轴差分吸收光谱技术（MAX-DOAS）在上甸子区域大气本底站开展了太阳散射光谱观测以及NO₂柱浓度反演研究。在NO₂的405～430nm特征谱段进行了定量光谱解析,并通过几何近似法计算了2009年7～9月NO₂对流层垂直柱浓度（VCD_trop）。观测期间NO₂ VCD_trop平均值和最大值分别为5.43×1015和7.15×1016 molec·cm-2。NO₂ VCD_trop日均值浓度水平较低,但总体上有上升趋势。NO₂ VCD_trop变化过程与风速风向关系密切：西南风时风速越小NO₂ VCD_trop越低,东北风对NO₂ VCD_trop有扩散稀释作用。NO₂ VCD_trop日变化形态总体上呈现为中午时段低、早晚较高的特征,并且傍晚峰值比早间峰值略高。上甸子站NO₂ VCD_trop浓度水平和日变化幅度相比北京城区同期观测结果明显偏小。NO₂ VCD_trop变化特征与河北香河和固城等污染相对较轻站点观测到的变化特征相一致。总之,MAX-DOAS能够有效监测区域本底大气的NO₂ VCD_trop,其变化特征与工业和交通排放、大气光化学过程、大气传输等复杂因素有关,还需积累更多数据和深入研究。     

天光背景下混浊大气中成像质量的分析方法

调制传递函数(MTF)定量描述混浊介质对图像质量的影响,它是混浊介质的固有光学特性,利用等效原理可以获得MTF从低频到高频的完整特征.在实际应用中,混浊介质中的图像质量不仅取决于介质的MTF,还与图像的背景辐射密切相关.本文从混浊大气中图像退化机理出发,理论分析了空间频域中天光背景下图像质量的退化过程.参考等效原理,提出了一种考虑天光背景的表观MTF,得到了表观MTF与介质MTF和天光背景的定量关系,从而得到了一种分析背景辐射下混浊介质中图像质量的有效便捷方法.针对图像质量优化方法,从空间频域的角度提出了一种评价原则.     

铷原子气体自旋噪声谱的测量与改进

利用自主设计并制作的基于现场可编程门阵列的实时傅里叶变换采集卡(FFTsDAC),采用线偏振光检测碱金属铷原子气样品中的自旋随机涨落(即自旋噪声谱).详细讨论了背景噪声以及自旋噪声随探测光光强的变化关系,证实了自旋噪声来自于系统中自旋的随机涨落.对比了两种FFTsDAC(8 bit采样的FFTsDACl和12 bit采样的FFTsDAC2)的测量性能,分析了影响实验信噪比的因素.FFTsDAC2具有更高的测量效率和采样深度以及更长的单次采样时间,因而具有更高的信噪比和更好的频率分辨率,与数值模拟的结果一致.