秸秆灰混凝土力学性能试验及强度预测

为了优化混凝性能,减少水泥产业耗能,尝试采用以部分秸秆灰替代水泥制备混凝土。该文通过试验对油菜秸秆灰混凝土拉压性能进行了研究,得到秸秆灰质量分数和水胶比对秸秆灰混凝土拉压性能的影响规律,如当秸秆灰质量分数增大时,混凝土拉压性能呈下降趋势;当水胶比过大时,混凝土力学性能急剧下降。同时提出秸秆灰混凝土抗拉性能与抗压性能间的线性函数关系以及混凝土轴心抗压强度计算公式,并与其他混凝土抗压强度公式进行比对验证。采用小波神经网络的预测方法,引入随机函数,对试验数据抽样进行训练,而后预测数据并与试验数据进行比对,计算误差,并将预测数据用于该文提出的拉压公式进行验证,结果表明验证较好。最后试验结果表明:当秸秆灰替代掺量为10%时,秸秆灰混凝土劈裂抗拉强度下降了25%,抗压强度仅下降了8%;当替代掺量为20%时,抗压强度下降了31%。     

重庆市伏旱频次气候特征分析

利用重庆市1960～2006年34个地面气象站逐日气象资料,采用Morlet小波分析方法分析了近47年来重庆市伏旱气候变化特征。结果表明,重庆伏旱天气有明显下降趋势;特重伏旱有＂先下降-后上升＂趋势,特别是从20世纪90年代开始上升趋势越来越明显。重庆市1995和2004年前后伏旱气候变化有明显的2～3年振荡周期;整个60年代,重庆市特重伏旱很稳定,没有明显的振荡变化。1970～1978年重庆市特重伏旱有明显的4～5年强振荡周期。     

近50年中国西北地区干湿演变的时空特征及其可能成因探讨

在全球大幅度变暖的背景下,西北地区的气候变化及其响应受到越来越多的关注。为了进一步探讨其气候变化过程与机理在时间与空间上变化的差异性,选取中国西北地区(80°E～115°E,32°N～50°N)1961-2004年140个气象台站逐日降水、日照、风速、水汽压、温度等资料,根据Penman公式计算了潜在蒸散量,并根据其与降水的关系建立了干燥度指数。采用自组织特征映射神经网络的方法,根据上述多种物理量进行西北地区内部的气候区划,寻找不同的区域异常中心。在此基础上,采用正交小波分解的方法,对各异常区域中心的干燥度序列进行分析。最后对北大西洋涛动指数对我国西北地区的区域气候变化的影响进行多时间尺度的相关分析,并从大气环流异常的角度解释其影响机制。     

基于小波变换的图像压缩方法研究

图像压缩是为适应特殊应用场合或为得到一个较好的视觉效果,例如突出某些细节,常常需要一种可以有效改变已有图像大小的方法,使图像压缩后仍然有较高的质量。本文采用一维小波变换和二维小波变换方法,将图像信息分解成低频和高频两部分,通过压缩算法,将图像数据重构成一幅信息完整的新图像。实验表明,采用本算法压缩后的新图像符合客观实际,图像数据信息丰富。     

我国西南地区典型县城气温演变特征——以贵州省湄潭县为例

利用线性趋势法对湄潭县1951 ~2009年逐日气温资料进行分析。结果表明,湄潭县气温总体呈上升趋势,以1980年为转折点,之前呈下降趋势,其后气温增加趋势加快。其中,年平均气温、年极端最高气温、年极端最低气温的气候倾向率分别为0.11、0.08和0·36℃/10 a;春、夏、秋、冬平均温度的气候倾向率分别为0.12、0.07、0.12、0.13℃/10 a。采用Morlet小波函数分析气温变化周期性,其存在不同尺度的周期,但自2000年以后不同时间尺度上大部分处在增温时期;且极端最高气温和最低气温的周期性具有一定规律：20世纪70年代之前,两者具有相反的变化规律,其极值交互发生;而20世纪80年代后期,两者具有相似的变化规律,其极值同时发生。在全球变暖背景下,湄潭县气温演变对全球变暖响应明显。     

Multi scale and multi orientation features for image de noising

An adaptive algorithm for image de noising is proposed based on the multi scale and multi orientation features. The coefficients in different scales and different directions are obtained by image decomposition using the nonsubsampled contourlet transform. Then thresholds functions are adaptively set with these coefficients. The texture of the image information is introduced by using the mean of decomposition scale and the energy of regional. The greater the energy, the more information of the texture while the same decomposition scales, the smaller the threshold is set. On the contrary, the greater the threshold is set. After the de noising and then reconstruction of these coefficients, image de noising is implemented. Compare to the wavelet transform threshold and contourlet transform threshold, the nonsubsampled contourlet transform pick up the image detail better and improve the quality of the image.     

Comparative study on the identification of structural modal parameter using different methods

Chongqing Chaotianmen Yangtze River Bridge is the world's longest-span arch bridge. The node connections on its main truss’s lower chords are to bear millions of large-amplitude stress cycles caused by automobile and light-rail train loads. However, there exists no referential designing and testing experience in such detailing on long-span steel bridges at home and abroad as yet. High-cycle fatigue behavior testing on a detailing model has been conducted to study the fatigue reliability of the bridge’s critical node connections. The testing cycling load on the model is determined according to conventional specifications and the expected traffic flow on the Bridge. The 1/2-scale detailing model is carefully fabricated to simulate the node prototype and undergo the 2 million-cycle testing with the design load. Through testing, fatigue reliability of Chaotianmen Yangtze River Bridge’s main-truss lower-chord node connections during the design service life is verified. In addition, static test data are compared with those calculated by finite element analysis to prove the validity of the node model. In the end, fatigue destruction test of the model was carried out to get the fatigue failure law of the node connection and provide necessary parameters and reference for designing and monitoring of this bridge in the future.     

Segmentation algorithm for urinary sediment image combiningwavelet transform and 2D Maximum entropy threshold

In order to solve the problem that urine sediment visible components cannot be segmented effectively because of complex components, complicated defocusing in image and poor discrimination between object and background, a method based on combination algorithm wis designed to segment urine sediment. The wavelet transform wis used to erase the effect of defocusing. Then morphology wis utilized to get the subimages that include the particles. The segmentation method combining the wavelet transform based segmentation and the two dimensional entropy threshold based segmentation wis employed to segment urine sediment visible components. Experimental results show that the proposed method can segment urinary sediment images effectively and precisely.     

用振荡指数描述去噪效果的仿真研究

在软门限消噪中,不同的信号波形对去噪效果的影响不同,为此,采用振荡综合指数(SIE)描述信号的振荡程度,用均方相对误差(RSE)描述消噪效果,并用振荡综合指数揭示信号的波形与信号的去噪效果的关系,结果表明,若振荡综合指数(SIE)越小,则去噪的效果越好。     

小波变换对敌百虫红外光谱去噪分析

采用小波变换滤波技术对敌百虫的红外光谱信号进行了去噪处理,利用小波变换滤波技术可以有效地消除红外光谱信号中的噪声,并结合滤波后重构光谱信号对农药浓度与峰面积进行一元线性回归建立其校正模型,并与直接用一元线性回归建立的校正模型进行比较。得出结论敌百虫农药的相关系数由原来的0.914 1提高到0.915。