混沌背景下微弱谐波信号的恢复

提出一种新的从混沌干扰中恢复微弱谐波信号的方法。首先根据混沌的几何性质,融合相空间重构技术和离散余弦变换,建立了一种新的分离谐波信号相空间投影方法。然后,从功率谱密度估计中提取谐波信号的频率,利用最小二乘估计提高谐波信号的恢复精度。仿真实验表明该方法具有高度的稳定性和可靠性。     

充水式橡胶坝技术在长山灌区渠首改造中的应用

简述了五常市长山灌区渠首充水式橡胶坝设计的技术要点及土建工程设计的技术要求,阐述了橡胶坝泄洪能力,坝袋及其锚固计算方法,评述了橡胶坝的优缺点.     

图像重建算法中的窗函数研究

对广角扇束扫描模式下的图像重建算法进行了研究．在引入实验的七种典型窗函数中，有限带宽、三角形窗以及余弦窗是卷积窗函数比较理想的选择．在图像重建，选择有限带宽窗时有较好的空间分辨率，三角形窗时有较好的密度分辨率。选择余弦窗时是空间分辨率与密度分辨率两者的折衷；从窗函数的频谱角度考虑。可用于图像重建的一个良好的卷积窗函数应该具备以下条件：（1）最小的3dB带宽B，即最小的主瓣宽度；（2）最小的旁瓣最大峰值A；（3）最大的旁瓣峰值衰减速度D．通过实验，验证了基于窗函数的卷积反投影图像重建算法可以有效地提高重建图像的质量．     

业务逻辑可重构的网络应用系统设计与实现

提出了一种应用软件可重构和可配置的方法,并对此进行研究。由此开发出企业信息化软件开发平台——ICET IP系统。ICET IP系统可适应不同应用逻辑需求,真正实现业务逻辑可重构和系统功能可配置,而且维护升级非常方便。     

轮齿干涉分析

通过数学计算有效的检测出齿轮副轮齿之间的干涉，并对避免干涉常用的设计准则的可靠性进行了评价。     

基于椭圆曲线的数字签名方案

本文介绍了有限域上的椭圆曲线以及椭圆曲线上的数字签名体制，并在数字签名体制基础上选择了两个基点，给出了一个新的基于椭圆曲线密码体制的数字签名方案。与以往的方案相比，它使用了双密钥，增强了安全性，同时具有椭圆曲线密码体制自身的优点。     

基于椭圆曲线自证实公钥的数字签名研究

提出了基于椭圆曲线的自证实公钥的构造方法;设计了一个基于椭圆曲线自证实公钥的基本数字签名方案和若干扩展数字签名方案,如盲签名、代理签名、多重签名等;分析了这些方案的安全性和效率。分析表明,以椭圆曲线自证实公钥来构造数字签名方案具有安全、高效的特点。     

Determination of J–R curves of thermoplastic starch composites containing crossed quasi-unidirectional flax fiber reinforcement

Thermoplastic starch (MaterBi) composites reinforced with quasi-unidirectional flax fiber in cross-ply (CP) arrangement were produced by film stacking followed by hot pressing. These composites, containing various amount of flax, failed ductilely with pronounced crack growth. Therefore, to determine their fracture mechanical behaviour the J-integral resistance curve concept (J–R) was applied. As the crack growth could not be traced, attempt was made to use the located acoustic emission (AE) events for that purpose. It was established that weighting and smoothing the located cumulative AE amplitudes the crack path can be correctly reconstructed. This was proved by collating the AE results with those derived from infrared thermographic (IT) inspection. Knowing the crack propagation at each point of the force–displacement curves the J–R curves could be determined. Both critical or initiation J-integral and tearing modulus went through a minimum with increase of flax content in the composites.     

J resistance behavior in functionally graded materials using cohesive zone and modified boundary layer models

This paper describes elastic–plastic crack growth resistance simulation in a ceramic/metal functionally graded material (FGM) under mode I loading conditions using cohesive zone and modified boundary layer (MBL) models. For this purpose, we first explore the applicability of two existing, phenomenological cohesive zone models for FGMs. Based on these investigations, we propose a new cohesive zone model. Then, we perform crack growth simulations for TiB/Ti FGM SE(B) and SE(T) specimens using the three cohesive zone models mentioned above. The crack growth resistance of the FGM is characterized by the J-integral. These results show that the two existing cohesive zone models overestimate the actual J value, whereas the model proposed in the present study closely captures the actual fracture and crack growth behaviors of the FGM. Finally, the cohesive zone models are employed in conjunction with the MBL model. The two existing cohesive zone models fail to produce the desired K–T stress field for the MBL model. On the other hand, the proposed cohesive zone model yields the desired K–T stress field for the MBL model, and thus yields J _R curves that match the ones obtained from the SE(B) and SE(T) specimens. These results verify the application of the MBL model to simulate crack growth resistance in FGMs.     

电力短期负荷时间序列混沌相空间重构参数优选法

采用混沌相空间重构方法进行电力短期负荷预测时,负荷时间序列的延迟时间τ、嵌入维数m以及预测参考点的选取对预测效果有很大的影响。该文通过电力短期负荷重构吸引子的形状和自相关函数确定电力短期负荷时间序列的最佳嵌入时间窗Γ;根据电力短期负荷的m、τ与Γ的函数关系确定m、τ的多组最佳匹配,证明了m、τ的最佳匹配对于负荷伸缩和平移的不变性;提出了选择预测参考点的适用而有效的方法,该方法分为粗搜索和细搜索2个过程,粗搜索主要根据距离选出一定数量的邻近点,细搜索主要根据相点演化的相关性排除“伪邻近点”。实际电网负荷预测的仿真结果验证了提出的电力短期负荷时间序列相空间重构参数优选法的正确性与有效性。