Viscosity dependence of electrochemical etching for gold tip fabrication

We suggest an electrochemical etching method with viscous etchant to enhance the sharpness of tip of scanning probe microscope. The viscosity of the etchant mixed with HCl solution and glycerol was used as a control parameter in addition to the voltage applied to the tip. In order to improve the sharpness of the tip, a nano-scale meniscus formed between the end of the tip and the liquid level was used. The shapes, aspect ratios, and radii of tips were measured depending on the concentration of the etchant. It was found that the tip etched with the mixed liquid with glycerol was sharper than the tip with the pure HCl solution. This can be explained by the fact that the meniscus formed by viscous liquid is maintained with a thinner diameter and causes final etching until the meniscus bridge is ruptured.     

Multi-scale retinex improvement for nighttime image enhancement

We propose a retinex improvement for nighttime image enhancement. Retinex is often used on images under non-uniform illumination in terms of either color or lightness and has satisfactory results to achieve color constancy and dynamic range compression. Few studies focus retinex on nighttime images, especially those under extreme conditions (i.e., images with over-lighted or extremely under-lighted areas or with noise speckles), on which retinex operation can perform badly. Original multi-scale retinex (MSR) is extremely sensitive to noise speckles that cameras produce in low light areas, and it has unsatisfactory effect on areas with normal or intensive illumination. Moreover, original MSR uses a gain-offset method for prior-to-display treatment and can lead to apparent data loss on nighttime images. This paper replaces the logarithm function in MSR with a customized sigmoid function to minimize data loss, and adapts MSR to nighttime images by merging results from sigmoid-MSR with original images. Experiments show our framework, when applied to nighttime images, can preserve areas with normal or intensive lighting and suppress noise speckles in extreme low light areas.     

List star edge coloring of k-degenerate graphs

A star edge coloring of a graph is a proper edge coloring such that every connected 2-colored subgraph is a path with at most 3 edges. Deng et al. and Bezegová et al. independently show that the star chromatic index of a tree with maximum degree $\Delta$ is at most $?\frac{3\Delta }{2}?$, which is tight. In this paper, we study the list star edge coloring of $k$-degenerate graphs. Let $c{h}_{st}^{\prime }\left(G\right)$ be the list star chromatic index of $G$: the minimum $s$ such that for every $s$-list assignment $L$ for the edges, $G$ has a star edge coloring from $L$. By introducing a stronger coloring, we show with a very concise proof that the upper bound on the star chromatic index of trees also holds for list star chromatic index of trees, i.e. $c{h}_{st}^{\prime }\left(T\right)\le ?\frac{3\Delta }{2}?$ for any tree $T$ with maximum degree $\Delta$. And then by applying some orientation technique we present two upper bounds for list star chromatic index of $k$-degenerate graphs.     

Effective contrast enhancement method for color night vision

Image fusion refers to the techniques that integrate complementary information from multiple image sensors’ data in a way that makes the new images more suitable for human visual perception. The paper focuses on the low color contrast problem of linear fusion algorithms with color transfer method. Firstly, the contrast of infrared and visible images is enhanced using local histogram equalization and median filter. Then the two enhanced images are fused into the three components of a Lab image in terms of a simple linear fusion strategy. To enhance the color contrast between the target and the background, the scaling factor is introduced into the transferring equation in the b channel. Experimental results based on three different data sets show that the hot and cold targets are all popped out with intense colors while the background details present natural color appearance. Target detection experiments through target recognition area, detection rate, target-background discrimination also show that the presented method has a better performance than the former methods.     

Erratum: The average degree of an edge-chromatic critical graph II

In the article “The average degree of an edge-chromatic critical graph II” by Douglas R. Woodall (J. Graph Theory 56 (2007), 194-218), it was claimed that the average degree of an edge-chromatic critical graph with maximum degree $\mathrm{\Delta }$ is at least $\text{◂⋅▸}\frac{2}{3}\left(\mathrm{\Delta }+1\right)$ if $\mathrm{\Delta }⩾2$, at least $\text{◂+▸}\frac{2}{3}\mathrm{\Delta }+1$ if $\mathrm{\Delta }⩾8$, and at least $\text{◂⋅▸}\frac{2}{3}\left(\mathrm{\Delta }+2\right)$ if $\mathrm{\Delta }⩾15$. Unfortunately there were mistakes in the proof of the last two of these results, which are now proved only if $\mathrm{\Delta }⩾18$ and $\mathrm{\Delta }⩾30$, respectively.     

Uniform random colored complexes

We present here random distributions on (D + 1)‐edge‐colored, bipartite graphs with a fixed number of vertices 2p. These graphs encode D‐dimensional orientable colored complexes. We investigate the behavior of those graphs as p→∞. The techniques involved in this study also yield a Central Limit Theorem for the genus of a uniform map of order p, as p→∞.     

Powers of edge ideals with linear resolutions

We show that if G is a gap-free and diamond-free graph, then I(G)^s has a linear minimal free resolution for every s≥2.     

基于5G边缘云的港口统一通信方案研究与实践

5G边缘云具有分布式、灵活组网、快速部署和本地流量分流等优势，在港口等垂直工业领域有很广泛的应用前景，同时对实现港口统一通信也提出了一定的要求。在研究基于5G边缘云的港口统一通信架构的基础上，提出了针对港口现场全域各类要素实现全面感知、支撑自动化业务改造的5G边缘云功能框架。此功能框架能很好地适用于港口场景的有线无线网络融合的统一承载，可作为目前复杂环境下的港口网络统一通信的网络基础设施。最后在某港口码头上对该方案进行了实际验证。     

水胁迫下典型盐生植被梭梭光谱特征分析

荒漠地区由于气候干燥，降水稀少，水分常成为制约植被生长的因素之一，水分胁迫对植物长势和产量的影响比任何其他胁迫都要大。随着高光谱技术的发展，国内外已有众多学者利用高光谱数据研究植被遭受胁迫作用，然而这些研究对象多集中于甜菜、棉花、玉米、水稻等作物，针对干旱区盐生植被遭受胁迫作用的研究较少。梭梭作为荒漠、半荒漠地区的典型盐生植被之一，具有极高的经济和生态效益。选择梭梭作为研究对象，培育一年生梭梭，并设置三个水分梯度，形成受不同水分量胁迫的梭梭。使用原始光谱、红边位置参数，结合植被指数及二维相关光谱研究其叶片光谱特征，为干旱区利用高光谱遥感监测盐生植被提供借鉴。结果表明：(1)分析梭梭叶片反射光谱曲线发现，在可见光至中红外各波段范围内，受不同水分量胁迫作用的梭梭叶片光谱反射率有显著差异。在可见光(350～610 nm)波段，各水分处理的梭梭叶片反射率依次为100 mL>500 mL>200 mL，这是由于100和200 mL水分促进梭梭内部叶绿素合成，使该波段反射率降低，而过多的水分(500 mL)对梭梭内部的叶绿素合成没有更大的促进作用。在红光区(611～738 nm)，随着水分量的增多，受不同水分量胁迫的梭梭叶片光谱反射率依次减小。在738～1 181和1 228～1 296 nm波段，受不同水分量胁迫作用的梭梭叶片光谱反射率为：200 mL>100 mL>500 mL；在1 182～1 227 nm波段，受不同水分量胁迫作用的梭梭叶片光谱反射率为：100 mL>200 mL>500 mL。这是由于植被细胞结构对近红外区域的反射率影响较大，因而受不同水分胁迫作用的梭梭叶片光谱反射率有显著差异。在1 300～1 365和1 392～1 800 nm波段，受各水分胁迫作用的梭梭叶片反射率为：100 mL>200 mL>500 mL。这表明在500 mL水分胁迫量范围内，水分越多，叶子的细胞液、细胞膜对水分的吸收能力越强，使得反射率下降。通过对原始光谱求取一阶导数并提取红边位置参数发现，各水分处理下的梭梭叶片一阶微分光谱曲线中红边位置未发生移动。这是由于梭梭在长期的干旱环境影响下，形成了特殊的适应机制，水分对其红边位置影响不敏感。(2)选取若干植被指数分析各水分处理下的梭梭光谱指数变化。当水分胁迫量由100 mL增至200 mL时，WI/NDWI，MSI和NDII指数值变化显著，可用于研究水分胁迫下梭梭的光谱特征。(3)使用二维相关光谱技术分析受各水分胁迫作用的梭梭光谱特征，得出在100 mL水分胁迫下，在536，643，1 219和1 653 nm波段处，吸收峰对水分的微扰敏感；在200 mL水分胁迫下，在846和1 083 nm波段处，吸收峰对水分的微扰敏感；在500 mL水分胁迫下，在835和1 067 nm波段处，吸收峰对水分的微扰敏感。总之，在近红外波段，与100 mL水分量相比，梭梭受200和500 mL水分量胁迫时，吸收峰对水分的微扰敏感度上升。由100 mL水分胁迫下梭梭的二维同步相关谱图可知，1 044和1 665 nm，1 072和903 nm，903和1 264 nm，1 230和1 061 nm波段处形成正交叉峰，表明这些波段处光谱强度随水分的干扰同时变化。