IVDAS: an interactive visual design and analysis system for image data symmetry detection of CNN models

Journal of Visualization - Convolutional neural networks (CNNs) have achieved breakthrough performance in image recognition and classification. However, it is still a challenge for CNNs to classify...     

高功率梯度掺杂增益光纤温度特性理论研究

在高功率光纤激光器中, 增益光纤的热效应是限制激光功率进一步提高的重要因素之一. 为了降低增益光纤的最高温度, 提出了一种通过改变增益光纤的掺杂浓度分布, 分散光纤激光的热效应, 从而提高激光输出功率的方法. 基于速率方程模型和热传导模型, 在光纤激光放大器输出功率大致相当的情况下, 对几种不同掺杂方式下增益光纤中的热分布和放大器的输出功率进行了数值模拟. 研究结果表明: 增益光纤的梯度掺杂可以优化光纤中的温度分布并提高光纤熔接点的稳定性; 同时兼具提高输出光束的光束质量、抑制光纤中非线性效应和模式不稳定的效果, 是提高光纤激光放大器输出功率切实可行的办法. 研究结果可以为高功率光纤激光器中增益光纤的设计提供一定的参考.     

Finite symmetry transformation group of the Konopelchenko-Dubrovsky equation from its Lax pair

Starting from a weak Lax pair,the general Lie point symmetry group of the Konopelchenko-Dubrovsky equation is obtained by using the general direct method.And the corresponding Lie algebra structure is proved to be a Kac-Moody-Virasoro type.Furthermore,a new multi-soliton solution for the Konopelchenko-Dubrovsky equation is also given from this symmetry group and a known solution.     

相位调制信号对窄线宽光纤放大器线宽特性和受激布里渊散射阈值的影响

高功率窄线宽光纤放大器的输出功率主要受限于受激布里渊散射(SBS)效应,通过相位调制进行线宽展宽可以有效抑制SBS效应.基于窄线宽光纤放大器中的SBS动力学模型,研究了正弦信号、白噪声信号和伪随机编码信号(PRBS)对窄线宽光纤放大器光谱特性与SBS阈值的影响.研究发现,采用不同信号进行相位调制时,调制频率和调制深度等参数对调制后激光光谱的谱线间隔、谱线数目与光谱平整度的影响存在较大差异,进而影响放大器的线宽特性和SBS阈值.通过对比分析,给出了调制信号的类型选择和参数优化原则,能够为窄线宽光纤放大器的相位调制系统设计提供参考.     

Label-free imaging of arterial cells and extracellular matrix using a multimodal CARS microscope

A multimodal nonlinear optical imaging system that integrates coherent anti-Stokes Raman scattering (CARS), sum-frequency generation (SFG), and two-photon excitation fluorescence (TPEF) on the same platform was developed and applied to visualize single cells and extracellular matrix in fresh carotid arteries. CARS signals arising from CH₂-rich membranes allowed visualization of endothelial cells and smooth muscle cells of the arterial wall. Additionally, CARS microscopy allowed vibrational imaging of elastin and collagen fibrils which are also rich in CH₂ bonds. The extracellular matrix organization was further confirmed by TPEF signals arising from elastin’s autofluorescence and SFG signals arising from collagen fibrils’ non-centrosymmetric structure. Label-free imaging of significant components of arterial tissues suggests the potential application of multimodal nonlinear optical microscopy to monitor onset and progression of arterial diseases.     

Regioselective hydroxylation of 2-hydroxychalcones by dimethyldioxirane towards polymethoxylated flavonoids

The flavone nucleus is part of a large number of natural products and medicinal compounds. In this presentation the novel regioselective hydroxylation of hydroxyarenes with DMD is described. The results showed further that flavonoids with 5-hydroxy group were selectively oxyfunctionalized at the para-position C8 carbon atom by DMD. Finally, according to this methodology, the naturally occurring isosinensetin, tangeretin, sinensetin, nobiletin, natsudaidain, gardenin B, 3,3′,4′,5,6,7,8-heptamethoxyflavone, quercetin and its derivatives were synthesized.     

Kinetics of 2,2′-Bipyridyl-Catalyzed Oxidation of Isopropyl Alcohol with Chromic Acid

2,2′-Bipyridyl and some substituted compounds catalyze effectively the oxidation of isopropyl alcohol by chromic acid. The reaction is first order in chromium(VI), alcohol and 2,2′-bipyridyl; it is first order in hydrogen ions at high acidity and slightly alters to second order at low acidity. The proposed mechanism shows that the rate-limiting step is mainly the decomposition of a termolecular complex to products. However, at low acidity, the formation step of this complex is a little less reversible and hence somewhat rate-limiting. Electron-donating substituents at the 4-position enhance the catalytic activity. Electron-withdrawing substituents at the 4- and 2-positions diminish the reaction rates by electronic and steric factors.     

Nanostructured Ag surface fabricated by femtosecond laser for surface-enhanced Raman scattering

Femtosecond laser was employed to fabricate nanostructured Ag surface for surface-enhanced Raman scattering (SERS) application. The prepared nanostructured Ag surface was characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The FESEM images demonstrate the formation of nanostructure-covered femtosecond laser-induced periodic surface structure, also termed as ripples, on the Ag surface. The AFM images indicate that the surface roughness of the produced nanostructured Ag substrate is larger than the untreated Ag substrate. The XRD and XPS of the nanostructured Ag surface fabricated by femtosecond laser show a face centered cubic phase of metallic Ag and no impurities of Ag oxide species. The application of the produced nanostructured Ag surface in SERS was investigated by using rhodamine 6G (R6G) as a reference chemical. The SERS intensity of R6G in aqueous solution at the prepared nanostructured Ag surface is 15 times greater than that of an untreated Ag substrate. The Raman intensities vary linearly with the concentrations of R6G in the range of 10(-8)-10(-4)M. The present methodology demonstrates that the nanostructured Ag surface fabricated by femtosecond laser is potential for qualification and quantification of low concentration molecules.     

ConfVisExplorer: a literature-based visual analysis system for conference comparison

Journal of Visualization - Given a research field, there are usually multiple conferences with different sizes and characteristics, and not all researchers have equal participations in all those...     

Finite symmetry transformation group of the Konopelchenkoben Dubrovsky equation from its Lax pair

Starting from a weak Lax pair, the general Lie point symmetry group of the Konopelchenko-Dubrovsky equation is obtained by using the general direct method. And the corresponding Lie algebra structure is proved to be a Kac-Moody-Virasoro type. Furthermore, a new multi-soliton solution for the Konopelchenko-Dubrovsky equation is also given from this symmetry group and a known solution.