神经网络分数阶PI~μD~λ在压电叠堆控制中的应用

为了克服压电叠堆的迟滞特性,实现压电叠堆的精确控制,建立了压电叠堆控制系统,研究了该系统所用到的神经网络、分数阶微积分等算法。首先,搭建了采集压电叠堆位移数据的硬件系统,并对含有噪声的位移数据进行了滤波处理;利用径向基函数(RBF)神经网络对压电叠堆建模,得到了模型参数。然后,利用RBF神经网络建模得到的Jacobain信息来整定分数阶PI~μD~λ控制器中的参数对压电叠堆进行控制。最后,与RBF整数阶PID对压电叠堆的控制效果进行了对比。结果显示:RBF建模误差仅为位移实测数据的0.22%,RBF神经网络分数阶PIμDλ控制系统输出稳定,很好地跟随了给定。得到的结果表明RBF神经网络分数阶PI~μD~λ控制器控制性能良好,在压电叠堆的控制中比RBF整数阶PID控制器表现得更加稳定、精确。     

二阶Wedgelet快速分解及其在工业CT图像线特征提取中的应用

为了对工业CT(ICT)图像中的线特征进行有效提取,提出一种基于二阶Wedgelet快速分解的特征提取方法。首先,介绍了二阶Wedgelet分解的定义,根据二阶Wedgelet基函数的构成将其划分为3种(同边型、邻边型、对边型)不同类型。根据不同类型基函数间的空间关系设计出二阶Wedgelet快速分解算法。在此基础上,在不同的单尺度上分别提取了各自的候选线特征。最后,结合多尺度四叉树结构,融合不同单尺度的候选线特征得到最终提取结果。对实际ICT图像进行了线特征提取实验,对比试验结果验证了提出方法的有效性和先进性,表明基于二阶Wedgelet快速分解的ICT图像线特征提取方法能有效地提取ICT图像感兴趣的线特征,对其它类型图像的线特征提取也具有一定的参考价值。     

Enabling the detection of UV signal in multimodal nonlinear microscopy with catalogue lens components

Using an optical system made from fused silica catalogue optical components, third‐order nonlinear microscopy has been enabled on conventional Ti:sapphire laser‐based multiphoton microscopy setups. The optical system is designed using two lens groups with straightforward adaptation to other microscope stands when one of the lens groups is exchanged. Within the theoretical design, the optical system collects and transmits light with wavelengths between the near ultraviolet and the near infrared from an object field of at least 1 mm in diameter within a resulting numerical aperture of up to 0.56. The numerical aperture can be controlled with a variable aperture stop between the two lens groups of the condenser. We demonstrate this new detection capability in third harmonic generation imaging experiments at the harmonic wavelength of ～300 nm and in multimodal nonlinear optical imaging experiments using third‐order sum frequency generation and coherent anti‐Stokes Raman scattering microscopy so that the wavelengths of the detected signals range from ～300 nm to ～660 nm.     

带阀消声器阀体开度变化的声学特性分析及应用

低频阶次噪声对排气噪声声品质有着重要的影响,带阀消声器成为消除排气低频噪声的手段之一。对带阀消声器进行试验分析和三维数值仿真,发现随着阀体开度的增加,共振器的共振频率向高频移动。进一步从实际带阀消声器结构中提取出一种可调声质量抗共振器子结构单元,采用三维数值方法和集总阻抗传递矩阵模型计算出不同开度下的阀体结构的声质量抗,建立共振器的集总阻抗模型。结果显示,阀体开度变化改变了共振器的声质量抗,而声质量抗是影响共振频率的关键因素,揭示出带阀消声器消除低频阶次噪声的机理。将带阀消声器和对比消声器进行实车测试。结果表明,带阀消声器起到跟踪消减低频阶次噪声的作用。     

Wrinkled interfaces: Taking advantage of surface instabilities to pattern polymer surfaces

The generation of nano-microstructured polymer film surfaces has been a challenge during the last decades. Advances in the fabrication of structured polymer surfaces to obtain micro and nano patterns have been accomplished following two different approaches, i.e., by adapting techniques, such as molding (embossing) or nano/microimprinting or by developing novel techniques including laser ablation, soft lithography or laser scanning among others. Thus, higher resolution capabilities are directly related with technological advances. In contrast to the use of highly sophisticated tools required by the above mentioned techniques, surface instabilities produced by different mechanisms take advantage of the inherent properties of polymers to induce particular surface patterns. Some of the surface instabilities are well known since decades but novel and old known instability mechanisms have been only recently extended their use to pattern polymer surfaces. This recent interest relies on the rich and complex patterns obtained as a result of self-organizing processes that are rather difficult if not impossible to fabricate by using traditional patterning techniques.Among the approaches to obtain patterned interfaces by means of surface instabilities the formation of wrinkles is the most explored method and will be the center of this review. The fabrication approaches employed to induce wrinkle formation and the possibilities to fine tune the amplitude and period of the wrinkles, the functionality and their final morphology are thoroughly described. Finally, an overview about the main applications in which buckled interfaces have been already employed or may have an impact in the near future is provided. Their use as templates, as flexible electronics, as supports with controlled wettability and/or adhesion or for biorelated applications are few of the fields in which the unique characteristics of wrinkled interfaces play distinguishing role.     

Comparative Mitogenomics of the Genus Odontobutis (Perciformes: Gobioidei: Odontobutidae) Revealed Conserved Gene Rearrangement and High Sequence Variations

To understand the molecular evolution of mitochondrial genomes (mitogenomes) in the genus Odontobutis, the mitogenome of Odontobutis yaluensis was sequenced and compared with those of another four Odontobutis species. Our results displayed similar mitogenome features among species in genome organization, base composition, codon usage, and gene rearrangement. The identical gene rearrangement of trnS-trnL-trnH tRNA cluster observed in mitogenomes of these five closely related freshwater sleepers suggests that this unique gene order is conserved within Odontobutis. Additionally, the present gene order and the positions of associated intergenic spacers of these Odontobutis mitogenomes indicate that this unusual gene rearrangement results from tandem duplication and random loss of large-scale gene regions. Moreover, these mitogenomes exhibit a high level of sequence variation, mainly due to the differences of corresponding intergenic sequences in gene rearrangement regions and the heterogeneity of tandem repeats in the control regions. Phylogenetic analyses support Odontobutis species with shared gene rearrangement forming a monophyletic group, and the interspecific phylogenetic relationships are associated with structural differences among their mitogenomes. The present study contributes to understanding the evolutionary patterns of Odontobutidae species.     

多层膜Laue透镜对10 keV硬X射线聚焦性能的理论计算

采用NbC/Si材料组合设计多层膜Laue透镜,总膜厚为40μm,利用衍射动力学理论分析多层膜Laue透镜对硬X射线的衍射效率及聚焦分辨率。通过两种方法提高多层膜Laue透镜的分辨率。第一种方式是减小膜层的最外层宽度,该方法要求结构必须是楔型结构,制备极其困难。第二种方法是使用多层膜Laue透镜的高级次,该方法在不增加制备难题的前提下能有效提高分辨率。通过使用多层膜Laue透镜的-3级次,对10keV硬X射线获得了分辨率为6.72nm,衍射效率为49.31%的聚焦光斑。     

基于携因素语义距离的定制西服订单聚类方法

为解决定制西服订单多样性和生产高效性的矛盾,利用大规模定制思想,结合定制西服订单商业特征到过程特征的映射建立了多段多级柔性西服物流编码系统,提出一种携因素语义距离订单聚类方法,该方法运用多级层次分析法确定了影响因素的权重,分析了编码属性的值域,将其分为有序属性和无序属性,并概念化得出了语义距离计算方法,采用改进的聚类识别算法对距离设计结构矩阵模型进行分割,实现了订单的聚类。通过实例计算表明了该方法能有效解决西服订单聚类问题。     

建筑的隐性线秩序形态

建筑线秩序形态与其内在规律,乃自成一体。外在线秩序形态有其内在规律,且内在规律具有明晰的线性机制特征。这些线性机制为形态的内核与机理,控制并转化为建筑线秩序形态;线秩序形态又是线性机制的逻辑物化表达,是其本体的外显与图解。该文是基于建筑线秩序形态与线性机制间的逻辑关系的研究,可以成为建筑本体与表现相契合的一种途径,对如何运用线秩序方法构思出符合内在线性机制的建筑线秩序形态,具有重要的意义。     

基于分数低阶统计量的双谱及其估计方法

稳定分布可更好地描述实际中所遇到的具有显著脉冲特性的随机噪声.为了更好地抑制信号背景中的非高斯噪声,本文提出了基于分数低阶的双谱定义,并给出在分数低阶有色噪声背景下双谱非参数和参数模型的估计方法.仿真结果表明,同传统的双谱估计相比较,非参数法分数低阶双谱估计能有效的识别信号,保留了信号的幅度和相位信息,但存在较大的估计方差.基于AR模型的分数低阶双谱估计具有最大的谱平坦度,能够有效地抑制噪声,具有良好的韧性.