隧道埋深及开挖方法对于二衬支护时机的影响

为了研究隧道埋深和施工方法对二衬支护时机的影响,以广梧高速公路牛车顶隧道为工程背景,建立数值计算模型,分别改变隧道埋深和施工方法,得到相应的隧道二衬支护时机.结果表明：通过数值计算,可定量得到二衬及掌子面之间的允许距离和埋深的关系;当埋深较小时,二衬与掌子面的允许距离随着埋深的增加而增加;当埋深超过某一限值时,隧道二衬与掌子面的允许距离基本不变;开挖工法对二衬与掌子面间的允许距离影响比较显著,而对仰拱与掌子面的允许距离影响很小.随着开挖断面分部的增加,开挖对围岩的扰动减小,因而可以适当延缓构筑二衬时机.若选取Ⅲ级围岩中的全断面开挖法作为参考基准,则围岩中二衬与掌子面的允许距离将由于选择不同工法需进行修正,相应的修正值为：全断面法1.0,上下台阶法和中隔壁法均为1.5.     

基于模糊神经网络的大场景人群密度估计方法 *

提出了一种估计大场景下密集人群密度的方法。该方法根据人类视觉的模糊性原理,认为用模糊集来划分人群密度范围比用确定的方法更符合人眼视知觉的认知方式,利用统计的方法确定灰度共生矩阵各指标对于各个密度类别的隶属函数;设计基于误差反向传播训练算法（BP）的模糊神经网络,计算样本模式对于各个密度类别的隶属度,并根据人群密度变化的时域连续性原理对人群密度范围进行合理估计。实验表明该方法提高了估计精度。     

基于参数依赖关系检查的测试用例空间约简方法

针对待测功能函数各参数间存在的控制或数据依赖关系,提出了一种利用符号执行约简测试用例空间的算法.具体内容包括:给出了基于控制流图的程序参数依赖关系定义;在此基础上,根据输入参数变量在程序执行时的信息流,提出了一种参数依赖关系的动态分析算法;将该方法应用于可信软件栈的功能测试中.实验结果表明:该方法在约简测试用例空间上具有较强的实用性,同时不会降低测试原有的检错能力.     

Interfacial tension of demixed polymer solutions near the critical temperature: polystyrene + methylcyclohexane

Interfacial tension between demixed solutions of polystyrene + methylcyclohexane has been measured near the critical temperature as a function of temperature using polystyrenes with molecular weights 9000 ～ 1.26 × 10⁶. The critical exponent for the interfacial tension was determined to be about 1.30 for the lower molecular weight systems. However, for higher molecular weights the exponent could not be obtained because the system departed from critical behaviour. Magnitudes of the interfacial tension were proportional to about N^?0.44, where N is the polymerization index. Experimental results were compared with the recently-proposed theories and found to be in qualitative agreement. The tricritical theory of polymer solutions was also compared with the experimental results.     

Pore Propagation Directions in P+ Porous Silicon

A comparative study is presented on the pore propagation directions of porous silicon layers (PSL) formed on p⁺-type substrates of different orientations. PSLs were formed on plain (0 0 1) and (1 1 1) silicon wafers as well as on structured (0 0 1) wafers containing facets of various orientations. During anodization, regular pores follow the 0 0 1 direction on the (0 0 1) planes. While on the (1 1 1) planes fewer regular pores develop and seemingly propagate closely to the 1 1 1 direction. These results indicate that the pores propagate perpendicular to the surface i.e. along the field lines when the surface orientation is either (0 0 1) or (1 1 1).When the silicon surface provided (1 1 0) orientation (Chuang, Collins, and Smith, 1989), or its position is in between the (0 0 1) and (1 1 1) planes then the pores do not propagate perpendicular to the surface but along the 0 0 1 direction.All the phenomena exhibited might be explained by presuming that during formation, the pores propagate along the 1 0 0 directions, and that those 1 0 0 directions are preferred which are closely to the field lines. In PSLs formed on (0 0 1) surfaces the field lines and the 0 0 1 crystallographic direction are coincident. However, in the (1 1 1) oriented wafer where three equally probable 1 0 0 directions exist around the field lines, more irregular structure of PSLs will develop.     

基于深度相机的手腕识别与掌心估测算法(HHME2013-ID51)

当手和手臂都进入深度相机所设定的有效深度范围时,它们将被作为一个整体来提取,若处理时也把它们作为一个整体,这可能会影响手势交互的一些重要算法,如掌心估测,手朝向估测,手的跟踪等。本文分析了手腕的运动特征和手的轮廓特点,并利用内切矩形的几何特征,提出了手腕识别算法来分割手与手臂;为了提高掌心估测算法的性能,本文分析了锐角三角形和最大内切圆的几何特征,并结合手势交互的特点,提出了新的掌心估测算法。经实验证明,手腕识别算法能较好地分割出手与手臂,新的掌心估测算法较之原算法在性能上有显著提高。     

基于流形学习的人体动作识别

目的 提出了一个基于流形学习的动作识别框架,用来识别深度图像序列中的人体行为。方法 从Kinect设备获得的深度信息中评估出人体的关节点信息,并用相对关节点位置差作为人体特征表达。在训练阶段,利用LE（Lalpacian eigenmaps）流形学习对高维空间下的训练集进行降维,得到低维隐空间下的运动模型。在识别阶段,用最近邻差值方法将测试序列映射到低维流形空间中去,然后进行匹配计算。在匹配过程中,通过使用改进的Hausdorff距离对低维空间下测试序列和训练运动集的吻合度和相似度进行度量。结果 用Kinect设备捕获的数据进行了实验,取得了良好的效果;同时也在MSR Action3D数据库上进行了测试,结果表明在训练样本较多情况下,本文方法识别效果优于以往方法。结论 实验结果表明本文方法适用于基于深度图像序列的人体动作识别。     

数字地球渲染中单精度浮点数误差改正

目的 针对全球大场景渲染中单精度浮点数的低精度导致的图像抖动和撕裂问题,提出了一套完整的解决方法。方法 首先,使用全球四叉树结构来寻找新的坐标原点,避免了现有算法需要频繁切换世界坐标原点的缺点;其次,在新坐标系下进行坐标转换和矩阵转换,解决了像素坐标计算的误差导致的抖动问题;最后,在GPU中使用基于对数的深度计算方式来提高深度的分辨率,解决了深度计算误差导致的Z-Fighting现象。结果 实验结果表明所提方法能很好地解决单精度浮点导致的渲染问题。结论 此方法具有适应性强、实现复杂度低、精度和效率可控等优点。     

基于自适应权值滤波的深度图像超分辨率重建

目的 越来越多的应用都依赖于对真实场景深度图像的准确且快速的观测和分析。飞行时间相机可以实时获取场景的深度图像,但是由于硬件条件的限制,采集的深度图像分辨率较低,无法满足实际应用的需要。为此提出一种结合同场景彩色图像通过构造自适应权值滤波器对深度图像进行超分辨率重建的方法。方法 充分发掘深度图像的非局部以及局部自相似性先验约束,结合同场景的高分辨率彩色图像构造非局部及局部的自适应权值滤波算法对深度图像进行超分辨率重建。具体来说,首先利用非局部滤波算法来有效避免重建结果的振铃效应,然后利用局部滤波算法进一步提升重建的深度图像质量。结果 实验结果表明,无论在客观指标还是视觉效果上,基于自适应权值滤波的超分辨率重建算法较其他算法都可以得到更好的结果,尤其当初始的低分辨率深度图像质量较差的情况下,本文方法的优势更加明显,峰值信噪比可以得到1dB的提升。结论 结合非局部和局部自相似性先验约束,结合同场景的高分辨率彩色图像构造的自适应权值滤波算法,较其他算法可以得到更理想的结果。     

Experimental methods in chemical engineering: X‐ray photoelectron spectroscopy‐XPS

X‐ray photoelectron spectroscopy (XPS) is a quantitative surface analysis technique used to identify the elemental composition, empirical formula, chemical state, and electronic state of an element. The kinetic energy of the electrons escaping from the material surface irradiated by an x‐ray beam produces a spectrum. XPS identifies chemical species and quantifies their content and the interactions between surface species. It is minimally destructive and is sensitive to a depth between 1–10nm. The elemental sensitivity is in the order of 0.1 atomic %. It requires ultra high vacuum ( Pa) in the analysis chamber and measurement time varies from minutes to hours per sample depending on the analyte. XPS dates back 50 years ago. New spectrometers, detectors, and variable size photon beams, reduce analysis time and increase spatial resolution. An XPS bibliometric map of the 10 000 articles indexed by Web of Science^[1] identifies five research clusters: (i) nanoparticles, thin films, and surfaces; (ii) catalysis, oxidation, reduction, stability, and oxides; (iii) nanocomposites, graphene, graphite, and electro‐chemistry; (iv) photocatalysis, water, visible light, and ; and (v) adsorption, aqueous solutions, and waste water.