基于故障支路电流序分量相位关系的选相元件

故障支路电流序分量之间的相位关系包含了明确的故障相别信息,但易受电流分布系数的影响。差电流中的负序分量的相位与故障支路中负序电流的相位相同;在差电流中的正序分量中减去系统电源产生的正序电容电流,修正后的正序差电流的相位与故障支路中的正序电流相同;通过负序差电流和修正后的正序差电流之间的相位关系可以明确判断故障类型。该选相元件不受线路分布电容、线路补偿电抗器、电流分布系数的影响,可在故障后长期使用,灵敏度高。仿真实验数据验证了该选相元件可以正确地选出故障相别。     

Novolac生产废水中游离酚含量的研究

采用一种新型催化剂合成Novolac树脂,研究了物料配比、催化剂浓度、反应时间及溶剂萃取等因素对Novolac生产废水中游离酚含量的影响,并通过4–氨基安替比林直接光度法对所产生的废水中游离酚含量进行了测定。结果表明,采用这种新型催化剂可使所产生的废水中游离酚含量控制在100 mg/kg以内,优化出了一种生产Novolac的绿色环保新工艺。     

豫北鹤壁市誉达灰岩矿山地质环境影响评估与恢复治理

在收集豫北鹤壁市区域基础地质资料和现状调查的基础上,评估了矿山地质环境影响,提出了对矿山地质环境恢复治理的方案.研究结果表明:矿体赋存在中奥陶统下马家沟组第三段灰岩、白云质灰岩及角砾状灰岩,矿体裸露地表.工业场地和3个采场均为矿山地质灾害和地形地貌景观影响严重区,矿山道路为矿山地质灾害和地形地貌景观影响较轻区;矿山开采...     

Self-assembling reduced graphene quantum dots on hematite photoanode for passivating surface states toward significantly improved water splitting

Hematite is a promising photoanode material but limited by its large overpotential (0.5–0.6 V) toward water splitting. The slow kinetics and high density of trapping states are the main factors. The former could be improved by catalyst modification for improved kinetics, while the latter is normally suppressed by passivating trapping states with atomic layer deposition-formed conformal overlayers. Up to date only a few of oxides and carbon materials were used to passivate hematite photoanode via wet chemical method, such as Al₂O₃, TiO₂ and reduced graphene oxide sheets. Herein, rGQDs as another carbon material are self-assembly onto hematite for the first time, which remarkably increases the photocurrent by 8.0 times at 1.23 V. The passivation of surface states confirmed by photoluminescence spectroscopy has significantly change in the radiative recombination, and can used well explain the great improvement. Importantly, this work clearly demonstrates a mass-productive and inexpensive solution-based self-assembly approach is also an efficient surface passivation technique.     

热水处理后环境放置期间黄瓜果实温度及抗氧化系统变化

为探讨热水处理后黄瓜果实在非低温贮藏环境放置期间果体温度及抗氧化系统的变化,该试验将热水处理(40℃、20 min)后的黄瓜果实在非低温贮藏环境[20℃,相对湿度(55±5)％]中放置不同时间(0、1、2、4、8 h),并同时测定其果体温度和抗氧化系统的变化.结果表明:热水处理后0 h黄瓜果体温度高达36.5℃,随后的...     

基于图像生成的多模态视网膜图像配准方法

针对多模态视网膜的全局粗配准,提出了一种基于图像生成的多模态视网膜配准方法. 不同于当前主流的提取多模态视网膜图像血管再进行配准的方法,使用GAN模型对不同模态的视网膜图像进行像素级映射,再通过特征点匹配的方式计算图像仿射矩阵,实现图像粗配准. 基于彩色眼底图像与荧光素血管造影图像的实验结果表明,该方法与当前主流的视网膜粗配准方法相比,具有快速且鲁棒的优势.     

湿法炼锌溶液中臭氧氧化除铁工艺及动力学研究

以臭氧为强氧化剂、ZnO为中和剂进行湿法炼锌溶液中Fe2+脱除的试验及动力学研究。考察初始Fe2+浓度、溶液pH、反应温度和O3流量等因素对除铁效果的影响。结果表明：增大pH、温度和O3流量可以显著增加除铁效率,而增加初始Fe2+浓度会降低除铁效率。宏观动力学研究表明,对比常用的拟一级、拟二级、Higbie和Avrami等动力学方程,臭氧氧化—沉淀除铁符合拟一级反应特征,受扩散控制,反应表观活化能为28.57 kJ/mol,动力学方程为r_(Fe^(2+) )=8.22[Fe^(2+) 〖]_0〗^(-0.74) [H^+ ]^(-0.51) Q_(O_3)^1.89 exp?〖(-3436/T〗)。     

Genome-Wide Identification of the Xyloglucan endotransglucosylase/Hydrolase (XTH) and Polygalacturonase (PG) Genes and Characterization of Their Role in Fruit Softening of Sweet Cherry

Fruit firmness is an important economical trait in sweet cherry (Prunus avium L.) where the change of this trait is related to cell wall degradation. Xyloglucan endotransglycosylase/hydrolase (XTH) and polygalacturonases (PGs) are critical cell-wall-modifying enzymes that occupy a crucial position in fruit ripening and softening. Herein, we identified 18 XTHs and 45 PGs designated PavXTH1-18 and PavPG1-45 based on their locations in the genome of sweet cherry. We provided a systematical overview of PavXTHs and PavPGs, including phylogenetic relationships, conserved motifs, and expression profiling of these genes. The results showed that PavXTH14, PavXTH15 and PavPG38 were most likely to participated in fruit softening owing to the substantial increment in expression during fruit development and ripening. Furthermore, the phytohormone ABA, MeJA, and ethephon significantly elevated the expression of PavPG38 and PavXTH15, and thus promoted fruit softening. Importantly, transient expression PavXTH14, PavXTH15 and PavPG38 in cherry fruits significantly reduced the fruit firmness, and the content of various cell wall components including hemicellulose and pectin significantly changed correspondingly in the transgenic fruit. Taken together, these results present an extensive analysis of XTHs and PGs in sweet cherry and provide potential targets for breeding softening-resistant sweet cherry cultivars via manipulating cell wall-associated genes.