Stochastic aspects of bridge deck aeroelasticity under turbulent flow

Returning to an earlier frequency-domain analysis of the problem of long-span bridge response to ambient winds, the paper emphasizes the indispensable experimental information necessary to bring results into conformity with full-scale prototype action. Focus is placed upon the use of a sectional wind tunnel model under simulated turbulent flow as the prime source of this information, which consists principally of the flutter derivatives and the spectra of the wind forces, both obtained under turbulent flow. The effect of three-dimensional turbulence upon the flutter derivatives is observed to influence structural stability in a manner consistent with that observed in full-bridge wind tunnel models.     

Pseudo-Stokes Vector Correlation From Complex Signal Representation of a Speckle Pattern and Its Applications to Micro-Displacement Measurement

Abstract:  As an improvement of the intensity correlation used widely in conventional electronic speckle photography, we propose a new technique for displacement measurement based on correlating Stokes-like parameters derivatives for transformed speckle patterns. The method is based on a Riesz transform of the intensity speckle pattern, which converts the original real-valued signal into a complex signal. In closest analogy to the polarisation of a vector wave, the Stokes-like vector constructed from the spatial derivative of the generated complex signal has been applied for correlation. Experimental results are presented that demonstrate the validity and advantage of the proposed pseudo-Stokes vector correlation technique over conventional intensity correlation technique.     

Transport properties of 1,1,1,2-tetrafluoroethane (R134a)

New equations for the thermal conductivity and the viscosity of R134a that are valid in a wide range of pressures and temperatures are presented. They were obtained through a theoretically based, critical evaluation of the available experimental data, which showed considerable inconsistencies between data sets, in particular in the vapor phase. In the critical region the observed enhancement in the thermal conductivity is well represented by a crossover model for the transport properties of fluids. Since thermodynamic properties enter into the calculation of the critical enhancement of the transport properties, a new fundamental equation for the critical region was developed also.Paper dedicated to Professor Joseph Kestin.     

基于方向直方图的手语识别方法研究

传统的手语识别方法基本都是利用离散的各帧静态图像进行识别,存在一定局限性,根据普通摄像头获得的视频图像,并采用方向直方图来获得单帧的静态特征矢量和各帧图像间的动态特征矢量.实现手语的识别.首先针对头两帧图像,通过手部边缘轮廓提取算法找到手的区域,然后从中提取出能表现手部形状的静态特征矢量.同时,对连续帧的图像做动作评估,获得手部移动的动态特征欠量.最后,将手部形状的静态特征与动态特征结合,采用使用欧氏距离作为矢量问匹配程度的度量算法以实现手语识别.实验对5个人的5种手语分别进行测试,均能正确识别,结果验证了该方法的有效性.     

数据缺失下学习贝叶斯网的SEM算法

针对SEM算法易收敛于局部最优的问题,提出一种改进SEM算法——DSEM-PACOB算法,采用PACOB算法提供的良好候选网络及合理的策略,估计节点变量缺失值,并使与待估节点变量紧密相关的若干节点变量直接参与估计。实验结果表明,与SEM算法相比,利用新算法获得的最终解的质量有所提高,且具有更好的稳定性。     

基于秩相关的属性约简

针对有序尺度变量,给出了有序信息系统与有序决策表在优势关系下的粗糙集约简定义;利用粗糙集方法将对象综合排序,进而得到一组秩;根据这些秩,运用非参数统计的思想研究了两个属性子集之间的相关性,并将Spearman秩相关系数作为属性相关性度量;在不改变总体序信息情况下,给出了基于此度量对有序信息系统与有序决策表进行约简的新方法。最后通过数值例子说明该方法是可行的,且为粗糙集方法提供了统计依据。     

子图直方图相关的图像置乱效果盲评判

为客观、自动地评价图像置乱效果,提出了一种基于子图直方图相关的图像置乱盲评判方法。该方法首先分析理想置乱图像的定义和特征,归纳总结最优置乱图像的直方图特点;然后,将待评判的置乱图像进行分块处理,建立各子图的直方图序列,利用各序列间的相关度给出置乱程度的评判测度。两种不同类型的置乱效果评判实验显示,与基于SNR的置乱评价方法相比,该方法不仅高效、灵活,评判不需要原始图像做参考,而且评判结果与人类视觉系统的主观感知相吻合,可快速有效判断图像置乱程度。     

SSCA算法改进及实现

SSCA(strip spectral correlation algorithm)算法是一种循环谱时域平滑算法.为了解决该算法运算量大,不能实时计算的矛盾,本文提出利用改进的滑动FFT算法和一位相关算法代替SSCA算法中滑动FFT和相关算法.给出了改进算法的数字实现方法和步骤,并用软件和硬件平台进行验证.仿真和试验结果表明:文中提出的数字实现算法能对信号的循环谱进行实时分析,能节约大量运算时间和存贮空间.基本解决了循环谱算法不能工程应用的问题.     

不同菌材培养料对茶树菇生长特性及营养品质的影响

目的 研究不同菌材培养料对茶树菇(Agrocybe chaxingu)生长特性和营养品质影响。方法 以贵州常见菌材构树(Broussonetia papyrifera)、刺槐(Robinia pseudoacacia)、光皮桦(Betula luminifera)、青冈(Quercus glauca)为栽培料,测定比较木材理化特性对茶树菇农艺性状及粗蛋白、多糖、粗脂肪、矿质元素和氨基酸含量的影响。结果 4种菌材对茶树菇菌丝生长速率影响不显著;构树培养茶树菇农艺性状最佳,其次为光皮桦;刺槐培养茶树菇粗脂肪和多糖含量最丰富。青冈培养茶树菇常量元素K、Mg、Ca、Na含量最高,构树培养茶树菇微量元素Fe、Zn、Cu含量最高;光皮桦培养茶树菇总氨基酸、必需氨基酸和限制性氨基酸含量最高。粗蛋白、Cu、Fe、Zn、苯丙氨酸、缬氨酸、Ca、Mg、苏氨酸、多糖、粗脂肪、K依次为区分4种菌材培养茶树菇主要指标。菌丝生长速率与全氮含量呈负相关性,培养基中菌丝生长速率与菌材半纤维素含量呈显著正相关性;子实体重量与木质素含量呈显著正相关性。结论 菌材理化性质对茶树菇生长及营养品质具有显著影响。构树和青冈培育茶...     

二次雷达目标数据处理软件设计

航管设备二次雷达捕获的目标数据A模式与C模式混杂,且每次扫描、询问某一确定目标的过程中需要对目标进行多次询问,导致数据量大大增加,后端数据处理压力增大.为解决上述问题,论文提出一种目标数据处理方案,首先对接收到的A、C模式数据进行点迹合并,再对批号数据与无批号数据分流处理,通过点迹关联、滤波跟踪、航迹管理等综合处理输出目标数据.试验结果表明该设计方案可实现目标航迹快速起始,并且在目标高机动、断续、交叉等复杂情况下能连续、稳定输出数据,具有较好实用价值.