基于改进Bubble函数的红外图像边缘提取方法

针对bubble函数不具有调节带宽的缺点，提出了一种改进的bubble函数，该改进函数能够通过调节参数来获取不同时域、频域响应和滤波效果。将改进后的bubble函数与平稳小波相结合构造出多分辨率网络，该网络利用平稳小波变换去除噪声、利用改进bubble函数增强图像边缘，从而可以准确、有效、快速的提取出图像的边缘。实验结果表明，该方法优于传统bubble函数与平稳小波相结合提取边缘的效果。     

A mean stress correction model for tensile and compressive mean stress fatigue loadings

A new mean stress fatigue model based on the distortional strain energy is proposed to account for the mean stress effects on fatigue life. The proposed model is compared with the Morrow and the Smith‐Watson‐Topper (SWT) mean stress correction models using a number of experimental data sets for one cast iron, two steels and two aluminium alloys under tensile and compressive mean stress loadings. It is found that both the proposed mean stress correction model and the SWT model yield similar results and provide very good correlation for positive mean stress data and moderate negative mean stress data. For high compressive mean stresses, the proposed model shows reasonably good correlations, while the SWT model fails to correlate the fatigue data. The Morrow model was found to give poor correlations for all fatigue data analysed by yielding conservative results for compressive mean stresses and non‐conservative results for tensile mean stresses.     

基于Java的GUI设计与实现

介绍了基于Java的 GUI软件开发的工具以及SWT的标准布局类,并给出了一个使用SWT中标准布局类设计GUI的实例.     

基于信噪比门限判断和小波变换的SAR干涉图滤波法

该文首先研究了一种基于离散小波变换(DWT)的干涉图滤波算法,对该算法的噪声模型和处理流程进行了详细的分析,并在其基础上做了基于静态小波变换(SWT)的改进。接着利用实测数据对这两种方法做了实验,通过对实验结果的分析,提出了一种高噪声环境下,在保证残点数降低率的同时,还能提高干涉条纹质量的滤波方法。在此滤波方法的基础上, 进一步提出了基于信噪比门限判断的干涉图两级处理滤波法,并对其处理流程做了详细的讨论。利用实测数据对该方法进行了仿真,实验结果验证了该方法的有效性。     

钢纤维增强水泥砂浆压剪联合冲击下动态剪切性能

基于唐志平等提出的剪切波跟踪技术(SWT),对钢纤维增强水泥砂浆进行了冲击速度40m/s~270m/s倾斜角为0~20°的斜撞击试验。研究结果表明,在此冲击速度下,材料处于损伤状态和由损伤状态向孔洞崩塌过渡阶段。此结果与聚丙烯纤维增强水泥砂浆的实验结果进行对比,发现钢纤维体积含量为0.5%时,对压缩性能的增强效果并不明显,但相应的剪切波速明显增加;当钢纤维体积含量为1%时对压缩性能和剪切波速均有较大的提高。由于钢纤维与水泥砂浆基体的强度相差太大,剪切强度有一定的改善,但数据较离散。同时通过对剪切结果分析表明,采用剪切波,尤其是卸载剪切波来探测脆性材料内部动态损伤非常有效。     

A single parameter to evaluate stress state in rail head for rolling contact fatigue analysis

Based on the Smith‐Watson‐Topper (SWT) method, a phenomenological approach for multiaxial fatigue analysis, the maximum SWT parameter is proposed as a single parameter to evaluate the stress state in the rail head for assessing the fatigue integrity of the structure. A numerical procedure to calculate the maximum SWT parameter from a finite element analysis is presented and applied in a case study, where the stress and strain fields due to wheel/rail rolling contact are obtained from a three‐dimensional finite element simulation with the steady‐state transport analysis technique. The capability of the SWT method to predict fatigue crack initiation in the rail head is confirmed in the case study. Analogous to von Mises stress for strength analysis, the maximum SWT parameter can be applied to evaluate the fatigue loading state not only in rail head due to rolling contact fatigue but also in a generic structure subjected to a cyclic loading.     

一种基于平稳小波变换的盲水印嵌入算法

为了解决一般数字水印算法无法在水印鲁棒性和不可感知性之间达到较好平衡的问题,提出一种基于平稳小波变换的盲水印嵌入算法.不同于常见的基于离散小波变换(DWT)的数字水印技术,该方案先对原始图像进行一级平稳小波变换(SWT),再将得到的低频近似区域进行8×8分块,从每个分块中选择一个嵌入位嵌入水印.通过计算所有嵌入位数值的平均值,并比较每个嵌入位数值和平均值的大小关系,计算得到密钥,利用密钥实现了水印的盲检测.实验结果表明,提出的盲水印算法不但具有较好的保真度,对于各种攻击也具有较强的鲁棒性.     

Ratcheting behaviour and mean stress considerations in uniaxial low-cycle fatigue of Inconel 718 at 649 °C

The ratcheting behaviour of Inconel 718 was investigated at 649 °C under uniaxial cyclic loading. Stress-control tests have been conducted at various combinations of stress amplitude and mean stress. The ratcheting strain at failure increases with increasing mean stress for a given stress amplitude and with decreasing stress amplitude for a given mean stress. Fatigue lives were correlated using three mean stress models: the Goodman equation, the Smith–Watson–Topper (SWT) parameter and the Walker parameter. It has been shown that the Goodman equation and the SWT parameter do not correlate life data, while the Walker parameter yields acceptable correlation. The SWT parameter was modified to incorporate the ratcheting effect. The new parameter is found to yield correlation similar to that of the Walker parameter.     

SWT线程安全问题及SWTTimer组件的设计与实现

本文分析了SWT中线程安全问题及其产生的原因,并给出了解决问题的方法.针对问题,设计出了SWTTimer组件,解决SWT中的线程安全问题,并降低了SWT编程的难度.