基于局部熵和方差调整的Noble角点检测算法改进

为了提高角点检测精度,增强算法对伪角点的抑制能力,在Noble算子的基础上充分考虑图像不同区域间灰度统计特性的差异,提出了一种基于局部熵和方差调整的Noble角点检测改进算法.该算法首先选择角点响应函数阈值以及非极大值抑制邻域大小的初始参考值,然后根据区域熵与区域方差分别估计这两个初始参考值的局部调整系数,最后用调整系...     

中药材贝母DNA不同提取方法的比较

目的探讨中药材贝母DNA的不同提取方法,为中药贝母的分子生物学鉴定提供参考.方法利用苯酚法、CTAB法、SDS法从中药贝母中提取DNA,通过紫外分光光度和琼脂糖凝胶电泳对所得DNA样品含量及纯度进行检测.结果利用3种不同的方法提取,药材贝母DNA的A260/A280在1.80±0.23左右.结论利用3种不同DNA提取方...     

常微分方程中的几个重要不等式

本文的目的是讨论常微分方程中的几个重要不等式之间的关系。我们首先是把文[4]中的微分(积分)不等式的结果从矩形域推广到条形域。并用统一的方法证明了贝尔曼不等式,格朗旺不等式和基本不等式,从而发现这三个不等式都是微分(积分)不等式的特殊情形。而且这些不等式左端的函数都是由一个一阶微分方程的初值问题的解所控制的,这样一来,本文就从两个侧面揭示了这三个不等式之间的相互关系和共同特性。     

学校学生信息管理系统的设计与实现

本论文介绍了学校学生信息管理系统的实现过程:包括系统分析、系统调查、系统功能设计、系统实现、数据库设计等。本系统主要功能有对学生信息、学生选课信息、学生成绩、教师信息的录入、修改、删除、查询等。     

Model for Predicting Roadside Concentrations of Traffic Pollutants

An analytical model is presented to estimate traffic pollutant concentrations based on an artificial neural network (ANN) approach. The model can analyze the highly nonlinear relationship between the traffic flow attributes, meteorological conditions, road spatial characteristics, and the traffic pollutant concentrations. This study analyzes the multiple factors that affect the pollutant concentration and establishes the model structure using the ANN technique. Collected data for the pollutant concentrations as functions of variant factors was used to train the ANN model. A method was developed to automatically measure the traffic flow attributes, such as traffic flow, vehicle speed, and flow composition from video data. The results indicate that the model can reliably forecast CO2 concentrations along the roads.     

基于三次非线性忆阻器的有源低通滤波器

忆阻器是具有记忆和连续输出特点的非线性电阻器,现已成为电路中的第4种基本元件。以一个三次光滑的非线性忆阻器模型为基础,与常见的有源低通滤波器相结合,利用电路分析的基本理论,分析该电路的频率响应特性,并与有源RC电路进行对比,对含有忆阻器的有源低通滤波电路进行电路仿真,其结果很好地验证了理论分析。     

A giant outburst two years before the core-collapse of a massive star

The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.     

Effects of Ru on microstructure stability and mechanical properties of Ni3Al single crystal alloy

The effect of Ru on microstructure stability and stress rupture properties of a Ni3Al single-crystal alloy was investigated. The experimental results showed that the addition of 2% Ru (mass fraction) improved the microstructure stability due to the res traint of harmful Y-NiMo phase formation during the thermal exposure at the high temperature above 1 000 °C. And the reason may be that the addition of Ru increased the degree of Mo supersaturation in both γ and γ′ phases, and hence suppressed the precipitation of Y-NiMo phase. The results of stress rupture tests under the testing condition of 1 100 °C, 120 MPa showed that the addition of 2% Ru in the alloy improved the stress rupture lives significantly for ther mal exposed samples. The improvement of the stress rupture properties may be attributed to the restraint of Y-NiMo phase precipitation and growth by the addition of the proper amount Ru.     

子结构分析的基本原理和ANSYS软件的子结构分析方法

目前子结构的理论日趋成熟完善,并且已经广泛用于结构分析计算,但是具体操作的论述较少,初学者要掌握这一高级的分析方法并非易事．针对这种现况,本文首先介绍了予结构的基本原理,然后简述美国SASI公司开发的ANSYS软件子结构的分析方法的基本步骤,并通过一个实例演示分析过程．为了进一步加深认识与提高子结构的分析水平,又对一个特殊横梁刚架作了予结构的分析论述,有力地说明了该方法的高效性．