弱M-可补子群对合成因子的影响

设G是有限群,P是G的一个Sylow p-子群,1<≤P。考虑|G|的素因子5和7,利用P的每一个阶为|D|的子群H在G中的弱M-可补性质,进一步探究了G的合成因子的结构。     

Interaction of Love waves with coupled cavity modes in a 2D holey phononic crystal

The interaction of Love waves with square array of pillars deposited on a cavity defined in a 2D holey phononic crystal is numerically investigated using Finite Element Method. First, the existence of SH surface modes is demonstrated separately for phononic crystals that consist of square arrayed holes, or rectangular arrayed Ni pillars, respectively in, or on, a SiO₂ film deposited on a ST-cut quartz substrate. The coupling between SH modes and torsional mode in pillars induces a transmission dip that occurs at a frequency located in the range of the band-gap of the holey phononic crystal. Second, a cavity is constructed by removing lines of holes in the holey phononic crystal and results in a transmission peak that matches the dip. The optimal geometrical parameters enable us to create a coupling of the cavity mode and the localized pillar mode by introducing lines of pillars into the cavity, which significantly improved the efficiency of the cavity without increasing the crystal size. The obtained results will pave the way to implement advanced designs of high-performance electroacoustic sensors based on coupling modes in phononic crystals.     

多层结构的阴极修饰层对有机电致发光器件的性能改善

为提高有机电致发光器件（OLEDs）的阴极电子注入效率,我们设计了新型的阴极杂化修饰层,其结构为Bphen∶LiF/Al/MoO₃,将其应用到器件ITO/NPB/Alq₃/Al中,参考器件的电子注入层选用传统材料LiF。实验研究表明,与传统的阴极修饰层LiF相比,基于这种杂化结构的阴极修饰层非常有效。测试了器件的电致发光光谱（EL谱）,其峰值位于534 nm,发光来自于Alq₃,实验中我们可以观察到明亮的绿色发光。将其与传统参考器件的EL谱进行对比,在电流密度40 mA·cm-2下,两个器件的电致发光光谱是一致的。在0～100 mA·cm-2范围内,对器件的EL谱进行了测试。实验结果表明,随着电流密度的增加,器件的发光增强,但是EL谱的形状和谱峰的位置是固定不变的。与参考器件对比,基于杂化修饰层的器件的发光性能更好。研究表明,杂化修饰层的最佳参数为Bphen∶LiF(5 nm; 6%)/Al(1 nm)/MoO₃(5 nm),在测试范围内,器件的最大电流效率和最大功率效率分别为4.28 cd·A-1和2.19 lm·W-1,相比参考器件提高了25.5%和23.7%。器件的电流密度-电压特性曲线表明阴极杂化修饰层可以增强电子的注入,使器件中的载流子更加平衡,从而提高了器件的发光性能。从两个角度对器件效率的增强进行了理论方面的论证。一方面利用阴极杂化修饰层的作用机制来解释。在HML中,LiF能填充Bphen的电子陷阱,增强电流的注入,同时HML也能限制空穴的传输,减小空穴电流。另一方面从电荷平衡因子的角度,HML增强了电子的注入,使得器件的电荷平衡因子增大,空穴和电子的平衡性更好。实验研究表明,阴极杂化修饰层很好地增强了器件的效率。     

Math1基因在内耳毛细胞发育及再生过程中的作用

耳蜗感觉毛细胞作为听觉机械感受器,在听觉的发生过程中起着至关重要的作用。 哺乳动物的毛细胞损伤后无法再生,往往会造成听力障碍或永久性听力缺失。因此,阐明内耳感觉毛细胞发育过程中的分子机制对听力损伤的诊断与治疗具有非常重要的意义。Math1是毛细胞发育与再生过程中的关键基因,本文就Math1及其相关基因和信号通路在毛细胞的发育与再生过程中的调控作用做简要概述。     

Adaptive signal enhancement for overlapped peaks based on weighting factor selection

Peak-sharpening is an effective method for the peak position detection of overlapped spectra. However, the weighing factor parameter strongly affects the sharpening performance, and the derivative adopted in the peak-sharpening method is sensitive to noise. In this paper, an adaptive peak-sharpening method based on weighting factor selection is proposed. The relationship between the sharpening ratio and weighting factor is studied. In addition, the Savitzky–Golay filter is adopted due to its excellent noise reduction and peak shape retention abilities. First, the smoothed signal and second-order derivative signal are obtained by the Savitzky–Golay filter. Then, the parameters of the overlapped peaks are estimated for the weighting factor selection. Next, the peak position is detected by the peak-sharpening method. After that step, the estimated parameters are updated, and the above steps are iterated until the detection of the peak position converges. Finally, the converged results are considered to be the final detection results. The experimental results using a simulated dataset, a virtual mass spectra dataset and a polarography dataset show that the proposed method is effective for peak position detection.     

特大型桥梁钢套箱防撞性能研究及碰撞过程推理

以优化特大型桥梁防撞钢套箱防撞效果为目标,对防撞钢套箱的设计构造、尺寸、钢板厚度等进行参数分析,探讨了钢套箱构造及钢板厚度等对防撞效果的影响规律,并对钢套箱与船舶碰撞过程进行推理．结果表明：合理地选取钢套箱的结构形式及尺寸,并使其刚度与碰撞船艏相匹配,可有效地减少对基础的局部破坏,使防撞钢套箱发挥更大的防撞效果．     

围压与径向荷载共同作用下巴西盘裂纹应力强度因子的解析解

利用权函数法推导了围压和径向荷载共同作用下,考虑裂纹面摩擦的预制裂纹巴西盘应力强度因子计算公式,从理论上分析了围压、径向荷载和裂纹面摩擦对巴西盘应力强度因子的影响。结果表明,围压对I型应力强度因子有很大影响,I型应力强度因子随围压的增大而减小。当裂纹面闭合后围压和摩擦系数对II型应力强度因子同样具有显著影响,考虑裂纹面有效剪应力的权函数法理论解与有限元数值解相吻合,表明理论分析的正确性。     

热对流作用下筒壁涂层的边裂行为

边裂(边缘开裂)是涂层热致损伤的主要模式之一. 边缘裂纹穿透涂层后,常导致界面脱粘从而驱使涂层与基体剥离,最终丧失对基体的保护作用. 本文以热应力强度因子表征边缘裂纹的扩展驱动力,研究筒壁涂层在热对流作用下的边裂行为. 首先,利用拉普拉斯变换法,得到了瞬态温度场及热应力场的封闭解. 其次,运用Fett等的三参数法确定了筒壁涂层边缘裂纹的权函数. 最后,基于叠加原理和权函数方法计算了边缘裂纹的热应力强度因子. 探讨了无量纲时间、边缘裂纹深度、基体/涂层厚度比、热对流强度等参数对热应力强度因子的影响规律. 结果表明:热应力强度因子的峰值既非发生在热载荷初始时刻,也非发生在热稳态时刻,而出现在时间历程的中间时刻;增大热对流强度不仅可提高热应力强度因子的峰值,而且使峰值提前出现;其他条件相同时,热应力强度因子随着边缘裂纹长度的增大而降低;增大涂层厚度或减小基体厚度可增强涂层抵抗瞬态热载荷的能力.      

A DAMAGE CONSTITUTIVE MODEL OF ROCK WITH CONSIDERATION OF RESIDUAL STRENGTH

基于岩石微元强度服从Weibull分布规律,引入损伤变量修正因子,建立了考虑残余强度影响的岩石损伤本构模型.运用多元函数求极值的方法,推导了含修正系数的模型参数\(m\)和\(F_{0}\)的理论表达式;对模型修正因子的选取进行了讨论分析. 结果表明：本文修正模型的实质是增加了一个含有修正系数的线性项;修正系数 \(\delta \)主要反映岩石的残余强度特征,选取合适的 \(\delta \) 值可以提高修正后本构模型的准确性.