置有竖直隔板鼓泡流化床物料停留时间

采用平均停留时间法研究了Geldart B类固体颗粒在内置竖直隔板鼓泡流化床的停留时间,在冷态试验台基础上研究了进料速率、流化风速、粒径、内置竖直隔板等因素对颗粒停留时间的影响。实验表明,进料速率、流化风速为影响停留时间的主要因素,且在一定的范围内三者之间有固定的关系,料径和中间的隔板高度的影响不大,两侧通流高度对停留时间几无影响。实验结果可为磁化焙烧鼓泡流化床物料停留时间和工业上采用竖直隔板提供理论依据。     

笔划宽度变换直方图的车牌识别中的应用

对于很多车牌识别中使用的算法而言,主要存在两种车牌类型：深色文字浅色背景车牌和浅色文字深色背景车牌。这两种车牌主要是二值化结果不同,进而导致后续字符分割和识别处理的图像类型不同。因此,判断车牌的二值化类型对于车牌识别来说是基础且重要的工作。本文提出了一种基于字符笔划宽度变换直方图的二值化算法,根据正色图像和反色图像计算比较两者笔划宽度变换直方图的最大值来判别车牌类型。同时,根据判别结果还可以估计笔划宽度,为局部二值化算法的邻域窗口大小的选择提供依据。我们使用多样式的美国车牌作为实验对象,与其他算法相比,实验结果表明该算法具有更好准确率,但也有更高的复杂度。     

HF激光脉冲与水柱表面相互作用产生电信号(英文)

研究了脉冲HF激光与水柱表面相互作用下电信号的产生过程。电信号显示了与激光能量线性相关的峰值间有时间间隔的两峰结构,且第二个尖峰在水柱底部的蒸汽腔塌缩后出现。实验还显示电信号的幅值和激光脉冲照射过程中是否存在膨胀和挤压的薄水层密切相关。如果在电池上边缘和石英平板(石英板紧邻电池,并与水柱上表面相接)之间存在一薄水层,电信号强度会增加10倍。     

偏压电场对压电板中Lamb波相速度的影响

本文研究了偏压电场作用下,Lamb波在压电板中的传播行为，首先给出了偏压电场作用时压电板中的应力场及电位移场，然后通过求解含初应力及初电位移的小幅波动问题的耦合方程，分别给出了Lamb波的对称模态和反对称模态的相速度方程，以典型的PZT－5H压电陶瓷板为例进行了数值计算,并讨论了偏压电场对Lamb波相速度及频散曲线的影响，结果表明，偏压电场可以显著地改变Lamb波的传播速度，借此可使声波器件获得延时效果。     

PROGRESSIVE FRAGMENT MODELING OF FAILURE WAVE IN CERAMICS UNDER PLANAR IMPACT LOADING

Polycrystalline ceramics have heterogeneous meso-structures which result in high singularity in stress distribution. Based on this, a progressive fragment model was proposed which describes the failure wave formation and propagation in shocked ceramics. The governing equation of the failure wave was characterized by inelastic bulk strain with material damage and fracture. And the inelastic bulk strain consists of dilatant strain from nucleation and expansion of microcracks and condensed strain from collapse of original pores. Numerical simulation of the free surface velocity was performed in good agreement with planar impact experiments on 92.93％ aluminas at China Academy of Engineering Physics. And the longitudinal, lateral and shear stress histories upon the arrival of the failure wave were predicted, which present the diminished shear strength and lost spall strength in the failed layer.     

锈蚀槽钢受弯承载力试验研究

通过7根锈蚀槽钢构件和2根未锈蚀槽钢构件的受弯试验,研究了锈蚀对槽钢受弯承载力的影响。试验表明:锈蚀槽钢的承载力随其点蚀因子的增大而降低;翼缘的锈蚀对钢构件受弯承载力的影响较腹板显著,其中受压翼缘与受拉翼缘影响程度基本相同。最后,结合试验结果,利用Matlab软件分别对锈蚀槽钢试件上、下翼缘点蚀因子与构件受弯承载力损失值进行数据拟合,定性地给出上、下翼缘点蚀因子与受弯承载力损失比之间的关系式。     

Photopolymerization mechanisms of acrylates in poly(methyl methacrylate) films

Photoinitiation processes for photopolymer coating layers have been investigated with respect to quenching rates by a laser flash photolysis using a total reflection cell, as well as to the decomposition‐quantum yield of a sensitizer dye and a radical‐generating reagent by a gel permeative chromatographic analysis (GPC); the sensitizer dye,2‐[p‐(diethylamino)styryl]naphtho[1,2‐d]‐thiazole (DNT) and the radical‐generating reagent, 2,2′‐bis(2‐chlorophenyl)‐4,4′,5,5′‐tetraphenyl‐1,1′‐bi‐1H‐imidazole (BI). From experiments using flash photolysis, strong fluorescence was observed at excitation of 355 nm laser pulse, though no transient absorption was observed. The fluorescence was statically quenched by BI with a quenching distance, R = 11 Å. From the experiments using GPC, the high‐quantum yield of decomposition (Φ) was obtained as Φ (DNT) = 3 and Φ (BI) = 9 for DNT and BI in the presence of acrylate monomers, trimethyrolpropanetri‐acrylate (TMPTA), at 488 nm exposure of 3.36 mJ cm which was required to form a photo‐hardened image, however no decomposition of DNT and BI was detected in the absence of TMPTA. The results imply that the photoinitiator system undergoes efficient static‐dye sensitization and efficient polymerization of the acrylate monomers accompanied with the chain decomposition of DNT and BI. Copyright © 1999 John Wiley & Sons, Ltd.     

无参考的车牌自动识别图像质量评价方法

提出一种针对车牌识别算法要求的车牌图像质量综合评价方法。其中根据车牌识别算法的普遍要求,归纳出了四种车牌图像质量评价因子:亮度偏移、亮度分布一致性、对比度、清晰度。最后使用主成份分析方法将四种评价因子综合起来建立得到对车牌图像的总体质量评价标准。采用这个评价标准,可以在无参考的情况下对单张车牌图像给出质量评价,为降低系统误差提供量化的依据,从而到达为识别算法提供高质量的输入图像的目的。     

薄板中弯曲波的特性阻抗

对薄板波动方程的一般解应用边界条件得到无限大薄板中弯曲波的解。进一步得到弯矩特性阻抗和剪切力特性阻抗的表达式,并给出了阻抗的曲线图。     

夹层板系统压缩力学性能试验研究

夹层板系统以其优越的力学性能在工程领域得到广泛应用。对夹层板系统在不同加载速率下的压缩力学性能进行了试验研究。首先对钢-聚氨酯-钢夹层板系统进行了准静态压缩试验,得到夹层板系统的准静态等效应力-应变曲线;并对同一组试样,基于分离式霍普金森压杆试验装置,进行了动态冲击压缩试验。近似等效SHPB试验原理,分析夹层板系统的动态力学性能。比较分析结构的破坏形式和原因,为新型结构的优化设计和应用提供参考。