边缘检测算法在不同分辨率图像中的性能研究

边缘检测是图像处理、计算机视觉中的重要内容之一,是实现图像分割、特征提取和图像理解的基础。也是仍未得到圆满解决的研究课题;图像分辨率是衡量图像质量的重要参数,分辨率越高图像质量越好,存储空间也越大;重点讨论了数字图像边缘检测中常用的几种经典的边缘检测算法对图像在不同分辨率时的性能变化,以及图像在不同分辨率条件下加入噪声时的性能变化,分析了造成这些变化的主要原因;同时,通过实验得出了这些边缘检测算法的优缺点和一些经验性结论,以便在实际应用中更好地发挥它们的特长;实验证明,这些边缘检测算法对图像和加噪图像在不同分辨率下的性能及其变化存在明显的差异。     

A comparative analysis of China and other countries in metabolic engineering: Output,impact and collaboration

In recent years, metabolic engineering has made great progress in both academic research and industrial applications. However, we have not found any articles that specifically analyze the current state of metabolic engineering in China in comparison with other countries. Here, we review the current development and future trends of global metabolic engineering, conduct an in-depth benchmarking analysis of the development situation of China’s metabolic engineering, and identify current problems as well as future trends. We searched publications in the Scopus database from 2015 to September 2020 in the field of metabolic engineering, and analyzed the output in general, including publication trends, research distribution, popular journals, hot topics and vital institutions, but also analyzed the share of citations, field-weighted citation impact, and production in collaboration with strategic countries in science and technology. This study aims to serve as a reference for later studies, offering a comprehensive view of China’s contribution to metabolic engineering, and as a tool for the elaboration of national public policy in science and technology.     

产氢发酵细菌的Biolog菌种鉴定与产氢能力

采用厌氧培养技术,从厌氧活性污泥中分离得到一株产氢发酵细菌。利用Biolog自动菌种鉴定仪对该产氢发酵细菌作了鉴定分析,确定了其在细菌学上的分类地位,新分离菌株Lactobacillus hilgardii(希氏乳杆菌)为生物制氢分离鉴定纯产氢菌种提供了指导。该株细菌为专性厌氧杆菌,蔗糖发酵液体末端主要产物为乙醇、乙酸,气相产物为H2和CO2,代谢特征为乙醇型发酵,在pH值为6.0和36℃条件下最大产氢量为58 mL H2.g-1蔗糖。     

木质素调控制备果糖基碳微球及其电化学性能研究

本研究使用果糖作为碳源,木质素磺酸盐协同三嵌段共聚物P123作为模板剂,经过水热碳化法和高温碳化法制备果糖基碳微球材料。探究了木质素磺酸盐对果糖在水热条件下的组装过程及调控机制,并分析果糖基碳微球材料在电化学领域的应用。结果表明,木质素磺酸盐的加入是微球表面形成波纹状突起的决定因素。经高温碳化处理过后得到中空多孔的Yolk-Shell果糖基碳微球材料具有良好的电化学性能,其比表面积为535. 04 m~2/g,孔容为0. 26 cm~3/g;在电流密度为0. 1 A/g时,其比电容为96 F/g,能量密度为3. 16 Wh/kg,功率密度为28. 06 W/kg。     

气体保护焊短路过渡熔滴成形的建模分析

提出了气体保护焊短路过渡过程中的熔滴成形的概念,并建立了模型.通过微距高速摄像技术和数字图像处理技术对熔滴成形过程中小滴状熔液所受的重力、电磁力以及表面张力提供的支持力进行了分析和定量计算,认为表面张力所提供的支持力远大于电磁力和重力共同导致的促使小滴状熔液下落的力.同时考虑了焊丝的熔化,认为以上因素最终造成小滴状熔液能以滴状的形态不断在焊丝端面进行扩展,形成熔滴.试验证明了熔滴成形这一模型的正确性.     

GMAW短路过渡过程中瞬时短路现象的分析

对GMAW短路过渡过程中的瞬时短路现象进行了力学动态分析,建立了基于熔滴液体压力、电磁收缩力、表面张力的瞬时短路力动态平衡临界条件.通过微距高速摄影技术和图像处理技术,获得了熔滴半径的变化数据,并结合电信号分析.结果表明,计算所得数值所反映的短路进程状态和图像所示的完全吻合,认为瞬时短路力动态平衡临界条件真实有效.并进一步基于此临界条件分析了熔滴形态对瞬时短路的影响,认为熔滴和熔池接触瞬间的径向半径如果小于轴向半径,则接触处的径向表面张力所产生的压力大于零,瞬时短路开始且不可逆,即纺锤形熔滴易造成瞬时短路.最后对瞬时短路现象进行了分类和定量研究,并提出了瞬时短路现象的新的解释.     

多晶Cu中Young’s模量和硬度与晶体取向的关系

采用纳米压入(nanoindentation)和电子背散射衍射(EBSD)技术对多晶Cu样品多个晶粒进行了微观力学性能表征和晶体取向分析.结果表明,Young's模量随晶粒表面法向方向(hkl)与(111)和(001)最小夹角的变化有明显的规律:(hkl)越接近(111),其Young's模量越大;(hkl)越接近(001),其Young's模量越小;而Young's模量随(hkl)与(110)最小夹角的变化无明显规律.硬度随(hkl)与(111),(110)和(001)最小夹角的变化均无明显规律.通过理论计算讨论了上述规律性.     

Comparison of encapsulation properties of major garlic oil components by hydroxypropyl β-cyclodextrin

The major garlic oil (GO) components were encapsulated by hydroxypropyl β-cyclodextrin (HP-β-CD), and their encapsulation properties were compared in this study. Our results showed that the optimal conditions for the GO encapsulation were as follows: weigh ratio at 12:88 (GO: HP-β-CD), pH at 5.0, and inclusion time at 4 h. Furthermore, results from the phase solubility curves indicated that two components of diallyl disulfide (DADS) and diallyl trisulfide (DATS) had higher water solubility caused by HP-β-CD and that DATS-HP-β-CD complex had higher stability constant (K _1:1 = 6.702 × 10⁵) and more significant change in free energy ( \Updelta G_\textCOMP^* \Updelta G_{\text{COMP}}^{*}  = −3.496 × 10⁴) than DADS-HP-β-CD. These findings indicated that DATS was better suited to be encapsulated by HP-β-CD compared to DADS. The result finally obtained from gas chromatography–flame ionization detector (GC–FID) confirmed the easier inclusion properties of DATS by HP-β-CD.     

Effect of ‘wheat Qu’ addition on the formation of ethyl carbamate in Chinese rice wine with enzymatic extrusion liquefaction pretreatment

Ethyl carbamate (EC), which has been confirmed as probably carcinogenic to humans, can be formed during the alcoholic fermentation of Chinese rice wine. In this study, EC and two possible precursors (urea and arginine) were analysed in wines fermented from rice processed by enzymatic extrusion liquefaction pretreatment, with different wheat Qu content gradients from 6 to 18% (dry basis, d.b.). The EC concentration decreased 22.5% with the addition of wheat Qu reduced to 6% for the enzymatic extrusion‐processed rice wine (EE). Moreover, although the arginine was generated 6.33–8.39 times higher in the enzymatic extruded rice, instead of the traditional treated rice at the same wheat Qu level, the corresponding level of urea formed from arginine was not high in the EE. In addition, rice treated by extrusion combined with enzymatic hydrolysis was found to be more utilizable and fermentable, and the lost quality of the final traditional rice wine with the low wheat Qu level (6–14%) could be improved using enzymatically extruded rice as the fermenting material. Therefore, it may be feasible to inhibit EC accumulation in Chinese rice wine by wheat Qu control, combined with enzymatic extrusion pretreatment for rice. Copyright © 2015 The Institute of Brewing & Distilling     

水性油墨新闻纸洗涤脱墨工艺探讨

本文对水性油墨废纸洗涤脱墨工艺的影响因素进行了研究。结果表明，水性油墨废纸洗涤脱墨的最优条件为：浆浓8％，碎浆温度50℃，碎浆时间10min，pH=7，脱墨剂脂肪醇聚氧乙烯（7）醚（AEO-7）用量0．6％。在此条件下，洗涤法脱墨可以提高脱墨浆白度6．5％ISO，使残余油墨量下降了950．2mg/kg。AEO-7的洗涤脱墨效果优于六偏磷酸钠和十二烷基磺酸钠。