高坝泄洪诱发场地振动响应分析及传播规律

为研究高坝泄洪诱发场地振动的问题,提出一种基于黏弹性人工边界的有限元数值模拟和水力学模型试验相结合的方法计算场地振动响应。以国内某工程为例,计算不同工况下场地振动响应,分析泄洪量和泄洪调度方式对场地振动的影响,揭示不同岩体条件下振动波的传播规律。结果表明:该工程各种泄洪方式都不会对周边居民的生活造成影响;泄洪量越大,下游场地振动响应越大,当3个溢洪洞泄洪条件一致时,采用2号洞泄洪最不利;同等泄洪条件下,采用4洞均分泄洪的振动响应小于按设计开度泄洪的振动响应;模型范围内放大振动波的主因是断层左右岩体性质的差异,断层的存在进一步加大了放大效应。     

中置式高压电容器柜改进设计

分析了南屯煤矿白马河风井变电所高压电容器柜原设计方案存在的问题,并对其进行了改进设计:选用适用于容性负载的真空断路器;添加放电线圈,并将放电线圈与电容器直接并联,使放电线圈与电容器组成一个完整的放电回路;添加接地开关,接地开关既有机械闭锁又有电气联锁,操作方便,安全性高。实际应用表明,改进设计后的高压电容器柜功能更加完善,更加安全、可靠。     

Characterization of acoustic signals due to surface discharges on H.V. glass insulators using wavelet radial basis function neural networks

A hybrid model incorporating wavelet and radial basis function neural network is presented which is used to detect, identify and characterize the acoustic signals due to surface discharge activity and hence differentiate abnormal operating conditions from the normal ones. The tests were carried out on cleaned and polluted high voltage glass insulators by using surface tracking and erosion test procedure of international electrotechnical commission 60587. A laboratory experiment was conducted by preparing the prototypes of the discharges. This study suggests a feature extraction and classification algorithm for surface discharge classification, which when combined together reduced the dimensionality of the feature space to a manageable dimension, by “marrying” the wavelet to radial basis function neural network very high levels of classification are achieved. Wavelet signal treatment toolbox is used to recover the surface discharge acoustic signals by eliminating the noisy portion and to reduce the dimension of the feature input vector. A radial basis function neural network classifier was used to classify the surface discharge and assess the suitability of this feature vector in classification. This learning method is proved to be effective by applying the wavelet radial basis function neural network in the classification of surface discharge fault data set. The test results show that the proposed approach is efficient and reliable.     

应用改进频率调谐的海上小目标检测方法

提出了一种新的基于可见光图像的海上小目标检测方法。由于频率调谐方法将图像空间域整体均值与高斯滤波后差分结果,作为显著性度量的标准,因此当图像背景中存在较多杂波干扰时,显著目标检测效果不理想。提出的方法对基于频率调谐的显著性检测方法进行了改进,首先对图像LAB空间中3个特征分量进行分块,在每个分块区域中应用频率调谐显著性检测方法,进而将其结果合并为总显著图,以检测海上小目标。该方法克服了频率调谐方法,当海面背景中存在大量海杂波,无法有效提取小目标的缺陷。实验结果表明了该方法的有效性。     

一种谱分解降维的模糊有监督局部保持投影策略

提出一种谱分解降维的模糊有监督局部保持投影策略。首先针对监督局部保持投影SLPP存在过学习和不能较好地保持图像空间的差异信息等问题,通过最小化局部离散度和最大化差异离散度准则提取投影方向,找到一种线性鉴别分析的等价形式。其次,通过采用模糊k近邻(FKNN)方法得到相应的样本分布隶属度信息,同时考虑到离群样本对整个分类结果的不利影响,提出一种模糊化方法,根据样本的隶属度对样本分布矩阵重定义所做的贡献,将每个样本的隶属度融入到SLPP特征抽取的过程中,从而得到完整有效的模糊样本特征向量集,有效解决了小样本问题的特征抽取问题。第三,提出一种谱分解的矩阵分析方法,在SLPP投影准则下,对散布矩阵实现降维。在ORL和NUST603人脸库上的实验结果验证了该方法的有效性。     

Chemical composition and bond structure of carbon-nitride films deposited by CH4/N2 dielectric barrier discharge

Carbon nitride films have been deposited by dielectric barrier discharge with a CH₄/N₂ gas mixture at different conditions. Fourier Transform Infrared (FTIR) spectroscopy, X-ray photo electron spectroscopy (XPS), Raman spectroscopy, Atomic force microscopy (AFM) and ellipsometry were used to systematically study chemical composition, bond structure and surface morphology of deposited films. Various bonds between carbon, nitrogen, hydrogen, and also oxygen were observed.     

再生砖混骨料混凝土柱的小偏心受压性能

通过小偏心受压性能试验对比研究3根的天然骨料混凝土柱和3根同强度全再生砖混骨料混凝土柱,强度分别为C25、C30和C35. 对6根柱进行加载试验,分析再生砖混骨料混凝土柱相比于同强度天然骨料混凝土柱在受力过程、破坏特征、变形能力与承载力等方面的差异. 试验发现,再生砖混骨料混凝土柱在小偏心加载至破坏的过程中,具有与天然骨料混凝土柱相似的3个受力阶段,且符合平截面假定. 与同强度的天然骨料混凝土柱相比,变形较大,但再生砖混骨料混凝土柱的极限承载力略高,原因可能在于两者轴心抗压强度的差异.     

小型预制桩基础承载特性数值模拟研究

本文建立硬化土本构模型,针对江苏省软土地区的土质条件选取数值计算参数,通过PLAXIS 2D软件对小型预制桩在的单桩水平受荷及竖向受荷进行数值模拟,得到桩身弯矩沿桩长的分布以及荷载-位移曲线,分析小型预制桩基础桩身弯矩的分布特点,并探求其在水平及竖向荷载作用下的承载特性,进而能够为小型预制桩基础工程设计以及计算方面提供一定的参考依据。     

OBSERVATION ON SPUTTERING SURFACE OF ALLOYS IN GLOW DISCHARGE

Glow discharge cathodic sputtering of alloys containing second phase precipitates or injectedoxide particles has been observed with energy dispersive X-ray spectrometer and scanningelectron microprobe.It was shown that the formation of cones during the sputtering in thesealloys is due to masking of the matrix by glow sputtering second phase precipitates or oxideparticles.At steady state,the density of cottes were found to be a function of the densities pre-cipitates or oxide particles in bulk alloy.In addition to the changes of local sputtering rate,theelectrostatic effect may play a role on the formation fo cones.