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BZ振荡反应实验的课程思政设计
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作者 淳远 杨立军 +1 位作者 杨金月 高卫 《大学化学》 CAS 2024年第2期72-76,共5页
传统BZ振荡反应实验着重于耗散结构知识的传授和诱导期反应活化能的测量。本案例基于同心圆生长过程呈现的丰富多彩的现象和蕴含的人生哲理,以耗散结构理论为支撑,对实验内容进行了创新设计,引入同心圆实验内容和翻转学习模式,在提升学... 传统BZ振荡反应实验着重于耗散结构知识的传授和诱导期反应活化能的测量。本案例基于同心圆生长过程呈现的丰富多彩的现象和蕴含的人生哲理,以耗散结构理论为支撑,对实验内容进行了创新设计,引入同心圆实验内容和翻转学习模式,在提升学生科学素养和研究能力的同时,引导学生分析实验中存在的安全隐患和对环境可能造成的影响,在实验过程中融入对人生的思考,在课后利用耗散结构相关原理去认识世界和改造世界。改进后实验将有助于树立学生正确的人生观和世界观。 展开更多
关键词 物理化学实验 BZ振荡反应 同心圆 课程思政 实验设计
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Study on Plant Diversity of Mountain Areas of Yangmeikeng and Chiao, Shenzhen, China 被引量:5
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作者 Hong Liang Yuyuan Huang +7 位作者 Shizhen Lin Kangsai Zhao Yufeng Zou Xinfan Yu lijun yang Wang Xu Zhu Ming Zhibin Zhou 《American Journal of Plant Sciences》 2016年第17期2527-2552,共26页
In this study, Yangmeikeng mountain area with a long-term natural restoration status (communities 1, 2, and 3) and Chiao mountain area with an artificially disturbed status (communities 4 and 5) in Shenzhen in China w... In this study, Yangmeikeng mountain area with a long-term natural restoration status (communities 1, 2, and 3) and Chiao mountain area with an artificially disturbed status (communities 4 and 5) in Shenzhen in China were subjected to plant community composition and diversity statistical analysis on the basis of the following indices: plant height;density;tree layer DBH;coverage;number of family, genus, and species;calculated diversity indices;richness;similarity coefficients of family, genus and species;and species evenness. The diversity levels of each index in each community were compared, and the relationships of family, genus, and species in the communities with one another were determined. The integrated diversity levels in the two areas were also analyzed. Results showed that the composition status of three communities, especially communities 2 and 3, which were located at high elevation, in Yangmeikeng with the long-term natural restoration status was better. The diversity values were also evidently higher. The vegetation composition in Yangmeikeng was also greater than that in Chiao. The integration status of numerous diversity indices, such as evenness and richness, was higher than that of the latter. These data could be used as a basis for arguments regarding the status of natural and artificial forest biodiversities. Many species in the community in artificial forests were shrubs and herbs. The richness and proportion of tree species were distinctly low. Thus, shrubs and herbs were the main components of the artificial interference community. The number and richness of the tree species in natural or long-term natural restoration forests were higher than those of the former. The family diversity D<sub>f</sub> of the three communities in Yangmeikeng was slightly lower than that of the two communities in Chiao. By contrast, the genus diversity D<sub>g</sub>, family richness, and genus richness in Yangmeikeng were higher than those in Chiao. In terms of α-diversity and similarity coefficient, family, genus, and species were not directly related to one another. Therefore, species, genus, and family composition should be combined with their diversity status in the statistical and biodiversity analysis of a community. Synthetic diversity indices should be further analyzed to evaluate the diversity status of a community objectively. 展开更多
关键词 DIVERSITY COMMUNITY FAMILY GENUS Species ECOSYSTEM
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从燃烧热测量求算化学反应热——“燃烧热的测定”实验改进
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作者 江豪 淳远 +4 位作者 李唐 张开宇 杨立军 高卫 杨金月 《大学化学》 CAS 2023年第10期288-292,共5页
经典物理化学实验“燃烧热的测定”主要涉及化学热力学中燃烧热知识点,为典型的验证性实验。本实验改进结合重要化学品邻苯二甲酸(酐)的生产过程,通过测量萘、邻二甲苯、邻苯二甲酸和邻苯二甲酸酐等几种物质的燃烧热,计算其合成过程的... 经典物理化学实验“燃烧热的测定”主要涉及化学热力学中燃烧热知识点,为典型的验证性实验。本实验改进结合重要化学品邻苯二甲酸(酐)的生产过程,通过测量萘、邻二甲苯、邻苯二甲酸和邻苯二甲酸酐等几种物质的燃烧热,计算其合成过程的反应热,既丰富了燃烧热实验的内容,又能和实际应用相关联。实验涉及几种原料廉价易得,均可测得准确的燃烧热数值,进而能获得可靠的反应热结果。采用线上、线下相结合的翻转学习教学模式,再通过几个反应过程测量的分工合作,可以有效地培养和提升学生的自主学习能力和团队协作精神。 展开更多
关键词 燃烧热 化学反应热 翻转学习 实验改进
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船体板缝布置设计优化
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作者 杨丽军 杨奇 《广船科技》 2023年第2期33-35,共3页
主要介绍通过板缝布置优化,达到船体板缝布置合理,满足材料订货要求的同时,减少现场拼板数量,降低施工难度。
关键词 板缝布置 船体 设计优化
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A Deep Learning-Based Crowd Counting Method and System Implementation on Neural Processing Unit Platform
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作者 Yuxuan Gu Meng Wu +2 位作者 Qian Wang Siguang Chen lijun yang 《Computers, Materials & Continua》 SCIE EI 2023年第4期493-512,共20页
In this paper, a deep learning-based method is proposed for crowdcountingproblems. Specifically, by utilizing the convolution kernel densitymap, the ground truth is generated dynamically to enhance the featureextracti... In this paper, a deep learning-based method is proposed for crowdcountingproblems. Specifically, by utilizing the convolution kernel densitymap, the ground truth is generated dynamically to enhance the featureextractingability of the generator model. Meanwhile, the “cross stage partial”module is integrated into congested scene recognition network (CSRNet) toobtain a lightweight network model. In addition, to compensate for the accuracydrop owing to the lightweight model, we take advantage of “structuredknowledge transfer” to train the model in an end-to-end manner. It aimsto accelerate the fitting speed and enhance the learning ability of the studentmodel. The crowd-counting system solution for edge computing is alsoproposed and implemented on an embedded device equipped with a neuralprocessing unit. Simulations demonstrate the performance improvement ofthe proposed solution in terms of model size, processing speed and accuracy.The performance on the Venice dataset shows that the mean absolute error(MAE) and the root mean squared error (RMSE) of our model drop by32.63% and 39.18% compared with CSRNet. Meanwhile, the performance onthe ShanghaiTech PartB dataset reveals that the MAE and the RMSE of ourmodel are close to those of CSRNet. Therefore, we provide a novel embeddedplatform system scheme for public safety pre-warning applications. 展开更多
关键词 Crowd counting CSRNet dynamic density map lightweight model knowledge transfer
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基于过程性质量的幼儿园生活活动评价指标体系的构建 被引量:6
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作者 杨莉君 张娟 郭念舟 《学前教育研究》 CSSCI 北大核心 2022年第1期10-21,共12页
幼儿园生活活动是幼儿在园的重要活动类型,对幼儿的学习与发展具有重要意义。幼儿园生活活动质量是幼儿园保教质量的有机组成部分,有必要基于过程性质量的视角构建幼儿园生活活动评价指标体系。本研究运用问卷调查、德尔菲专家访谈及文... 幼儿园生活活动是幼儿在园的重要活动类型,对幼儿的学习与发展具有重要意义。幼儿园生活活动质量是幼儿园保教质量的有机组成部分,有必要基于过程性质量的视角构建幼儿园生活活动评价指标体系。本研究运用问卷调查、德尔菲专家访谈及文献分析等方法,首先尝试探索幼儿园生活活动评价初始指标,编制出预测问卷,再经项目质量分析、探索性因子分析以及验证性因子分析,形成正式问卷,最后进行信效度检验。研究结果表明,从生活常规与管理、互动与支持、科学照料3个一级指标及其包含的7个二级指标、32个三级指标对幼儿园生活活动质量进行评价是科学合理的。整个评价指标体系体现了过程性、情境性特点和以“预防为主”的指向,可以为改善幼儿园生活活动质量提供有效依据。 展开更多
关键词 过程性质量 生活活动 教育质量
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基于双小波变换的抗干扰电压暂降检测方法研究 被引量:5
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作者 许丹 黄利军 +3 位作者 杨校辉 李献伟 王毅 李博 《电气工程学报》 2018年第4期32-37,52,共7页
针对目前电压暂降检测时存在的由于噪声和谐波等干扰导致的分析精度差、实时性不高等问题,提出一种基于双小波变换的电压暂降检测方法。该方法首先采用db20小波对信号进行多尺度分解,提取含暂降信息的基波信号。然后采用db10小波对基... 针对目前电压暂降检测时存在的由于噪声和谐波等干扰导致的分析精度差、实时性不高等问题,提出一种基于双小波变换的电压暂降检测方法。该方法首先采用db20小波对信号进行多尺度分解,提取含暂降信息的基波信号。然后采用db10小波对基波信号进行单尺度分解,检测高频分量的模极大值对电压暂降实现定位,从而降低了噪声和谐波等干扰信号的影响,提高了小波分析的检测性能。 展开更多
关键词 电压暂降 小波变换 双小波 噪声 谐波
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Studies on Ecological Monitoring of Plant Community and Plant Diversity in Shenzhen, Southern China
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作者 Yuyuan Huang Xinfan Yu +31 位作者 Hong Liang Zhiming yang Haiyang Wen Zhen Ye Yunhe Lu Ruoyu Wei lijun yang Song Ma Kangsai Zhao Fan Wang Zhijie Chen Huina yang Chengxi Jiang Bin Xu Weimin Wang Wang Xu Zhu Ming Shizhen Lin Hao Liu Hualiang Luo Suni Deng Lijuan Huang Yanjun Lei Xiaoli Wan Yahe Li Wanmin Zhou Shun Zhao Zhenliang Duan Dongyao Liao Xiaobo Qiu Haoqun Huang Linlin Jiang 《Open Journal of Forestry》 2021年第4期352-380,共29页
From Jan</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2013 to Nov</span><span style="font-family:Verdana;">.<... From Jan</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2013 to Nov</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2018, we carried out the investigation on vegetation studies in the ecological monitoring programs, Shenzhen</span><span style="font-family:Verdana;"> and</span><span style="font-family:""><span style="font-family:Verdana;"> totally researched 170 plant communities of mountain areas etc., </span><span style="font-family:Verdana;">few areas of street regions and parks etc., for communities’ structural characteristics and plant diversity. We comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level and the main affected factors. We also researched and analyzed these communities’ structural characteristics and pant diversity, </span><span style="font-family:Verdana;">comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level, the main affected factors;researched and analyzed the relationship between plant community structure characteristics with the absorbing ability to PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;"> pollutants. The result showed that the structure and plant diversity of natural </span><span style="font-family:Verdana;">forest </span></span><span style="font-family:Verdana;">were </span><span style="font-family:Verdana;">obviously better than</span><span style="font-family:Verdana;"> artificial disturbed forest or artificial forest, the semi-natural forest w</span><span style="font-family:Verdana;">as</span><span style="font-family:Verdana;"> the middle level of the forests, In the indices of height, DBH, coverage and crow width etc. of tree layer, natural forests and semi-natural forests were obvious higher than that of artificial disturbed forest or artificial forest;in some forests of artificial disturbed forest or artificial forest, though their richness indices of family and genus were a slightly higher, but this contribution was majorly due to herb layer plants, and some shrub layer plants. Analyz</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> three kinds of communities, the number of tree layer species of natural forest was</span><span style="font-family:Verdana;"> the </span><span style="font-family:""><span style="font-family:Verdana;">largest, and their every </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity index value was </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">highest;these characteristics values of semi-natural forest were second, artificial disturbed forests or artificial forests were </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">lowest;in shrub layer, and herb layer, few </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity indices of artificial disturbed forest or artificial forest were </span><span style="font-family:Verdana;">a slightly higher than that of some natural forests, but the integral values of the diversity indices of natural forest and semi-natural forest were obvious</span></span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> higher than the former. The research showed that in the artificial disturbed forest or artificial forest, because there have some little scale clearing area</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;">, so some pioneer plant species could enter the community and formed a temporarily </span><span style="font-family:Verdana;">increase of species diversity, however</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> these species major </span><span style="font-family:Verdana;">were</span><span style="font-family:Verdana;"> some shrub and herb plants;but tree layer possessed obvious</span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> more, even surpass</span><span style="font-family:Verdana;">ed</span><span style="font-family:Verdana;"> several ten times biomass than shrub and herb layers</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> Therefore</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> the respect</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of maintain ecosystem stability and other</span><span style="font-family:Verdana;"> ecological efficient have </span><span style="font-family:Verdana;">major and dominated position and so on;and then this community can </span></span><span style="font-family:Verdana;">be </span><span style="font-family:Verdana;">natural recovery and succession, those forementioned new entire plants shall withdraw from the community and are replaced by the original plants of the community;but this process has already caused the ecological efficient loss and ecosystem unstable. Above research results are better evidence and theory reference to the argument problems on that </span><span style="font-family:Verdana;">are</span><span style="font-family:""><span style="font-family:Verdana;"> natural forest and natural restoration forest biodiversity higher? or is artificial forest biodiversity higher? and or is more artificial disturbed forest higher?</span><span style="font-family:Verdana;"> Our researches showed that used random investigation method set quadrats, and combined typical investigation method, the structural indices in the all layer of community and all diversity indices of tree, shrub and herb layers and the integral values </span></span><span style="font-family:Verdana;">were</span><span style="font-family:""><span style="font-family:Verdana;"> similar, same or usually these indices in the community which set 600 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, 800 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total quatrat area were higher (</span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity) than that of more than 3000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, 4000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> or 7000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, even more than 17,000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total qua</span></span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;">rat area of communities. These lot</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of researches further proved that according to minimum area method for vegetation survey, in subtropical region, using random investigation method combined with typical investigation set 400 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> or 400 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> - 500 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total qua</span></span><span style="font-family:Verdana;">d</span><span style="font-family:""><span 展开更多
关键词 SHENZHEN VEGETATION COMMUNITY Structure DIVERSITY PM2.5 Ecological Monitoring Natural Forest Artificial Forest
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Negative regulation of miRNA-9 on oligodendrocyte lineage gene 1 during hypoxic-ischemic brain damage 被引量:5
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作者 lijun yang Hong Cui Ting Cao 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第5期513-518,共6页
Oligodendrocyte lineage gene 1 plays a key role in hypoxic-ischemic brain damage and myelin repair, miRNA-9 is involved in the occurrence of many related neurological disorders. Bioin- formatics analysis demonstrated ... Oligodendrocyte lineage gene 1 plays a key role in hypoxic-ischemic brain damage and myelin repair, miRNA-9 is involved in the occurrence of many related neurological disorders. Bioin- formatics analysis demonstrated that miRNA-9 complementarily, but incompletely, bound oligodendrocyte lineage gene 1, but whether miRNA-9 regulates oligodendrocyte lineage gene 1 remains poorly understood. Whole brain slices of 3-day-old Sprague-Dawley rats were cultured and divided into four groups: control group; oxygen-glucose deprivation group (treatment with 8% O2 + 92% N2 and sugar-free medium for 60 minutes); transfection control group (after oxygen and glucose deprivation for 60 minutes, transfected with control plasmid) and miRNA-9 transfection group (after oxygen and glucose deprivation for 60 minutes, transfected with miRNA-9 plasmid). From the third day of transfection, and with increasing culture days, oligodendrocyte lineage gene 1 expression increased in each group, peaked at 14 days, and then decreased at 21 days. Real-time quantitative PCR results, however, demonstrated that oligoden- drocyte lineage gene 1 expression was lower in the miRNA-9 transfection group than that in the transfection control group at 1, 3, 7, 14, 21 and 28 days after transfection. Results suggested that miRNA-9 possibly negatively regulated oligodendrocyte lineage gene 1 in brain tissues during hypoxic-ischemic brain damage. 展开更多
关键词 nerve regeneration brain injury miRNA-9 oligodendrocyte lineage gene 1 hypox- ic-ischemic brain damage premature birth brain slice culture NSFC grant neural regeneration
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Hierarchical sulfur and nitrogen co-doped carbon nanocages as efficient bifunctional oxygen electrocatalysts for rechargeable Zn-air battery 被引量:5
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作者 Hao Fan Yu Wang +8 位作者 Fujie Gao Longqi yang Meng Liu Xiao Du Peng Wang lijun yang Qiang Wu Xizhang Wang Zheng Hu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2019年第7期64-71,共8页
Exploring inexpensive and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) is critical for rechargeable metal-air batteries. Herein, we report a new 3D hier... Exploring inexpensive and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) is critical for rechargeable metal-air batteries. Herein, we report a new 3D hierarchical sulfur and nitrogen co-doped carbon nanocages(hSNCNC) as a promising bifunctional oxygen electrocatalyst by an in-situ MgO template method with pyridine and thiophene as the mixed precursor. The as-prepared h SNCNC exhibits a positive half-wave potential of 0.792 V(vs. reversible hydrogen electrode, RHE) for ORR, and a low operating potential of 1.640 V at a 10 mA cm-2 current density for OER. The reversible oxygen electrode index is 0.847 V, far superior to commercial Pt/C and IrO2,which reaches the top level of the reported bifunctional catalysts. Consequently, the hSNCNC as air cathodes in an assembled Zn-air battery features low charge/discharge overpotential and long lifetime. The remarkable properties arises from the introduced multiple heteroatom dopants and stable 3D hierarchical structure with multi-scale pores, which provides the abundant uniform high-active S and N species and efficient charge transfer as well as mass transportation. These results demonstrate the potential strategy in developing suitable carbon-based bi-/multi-functional catalysts to enable the next generation of the rechargeable metal-air batteries. 展开更多
关键词 3D HIERARCHICAL CARBON NANOCAGES S N CO-DOPING BIFUNCTIONAL electrocatalysis Zn-air battery
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Strength and deformation behaviors of bedded rock mass under bolt reinforcement 被引量:9
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作者 Wenxin Zhu Hongwen Jing +2 位作者 lijun yang Bing Pan Haijian Su 《International Journal of Mining Science and Technology》 EI CSCD 2018年第4期591-597,共7页
The mechanism of bolt support is an important topic in mining engineering and slope treatment. The artificial material and loading system were self-developed to study the influence of bedding cohesion and bolt number ... The mechanism of bolt support is an important topic in mining engineering and slope treatment. The artificial material and loading system were self-developed to study the influence of bedding cohesion and bolt number on the anchoring behavior of bedded rock mass. The results show that, both peak strength and elasticity modulus increase gradually with the increase of bedding cohesion and bolt number. The axial stress–strain curve of bedded rock mass under the reinforcement of bolts presents the features of strain-softening and secondary strengthening. Finally, anchoring behavior of bedded rock mass with different bolt numbers was simulated by using FLAC3 D numerical program and the results were compared with the experimental results. This study can provide certain bases to the stability control and support design of bedded rock mass in roadway. 展开更多
关键词 Bedded rock mass Anchoring behavior Peak strength Bedding cohesion Secondary strengthening
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Nitrogen and atomic Fe dual-doped porous carbon nanocubes as superior electrocatalysts for acidic H2-O_(2) PEMFC and alkaline Zn-air battery 被引量:2
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作者 Xiudong Shi Zonghua Pu +6 位作者 Bin Chi Mingrui Liu Siyan Yu Long Zheng lijun yang Ting Shu Shijun Liao 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第8期388-395,I0008,共9页
Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited ca... Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited catalytic activity or high cost,which thus hinder their applications.Herein,we designed ZIF-8 derived nitrogen and atomic iron dual-doped porous carbon nanocubes as high-quality catalysts for ORR,through a novel gas-doping approach.The porous carbon nanocubic architecture and abundant Fe-Nxactive species endow ZIF-8 derived single atomic iron catalyst(PCN-A@Fe SA)with superior catalytic activity,and surpass Pt/C and a majority of the reported catalysts.Both XAS and DFT calculations suggest that Fe2+N4 moieties are the main active centers that are favorable for oxygen affinity and OH*intermediate desorption,which can result in promising catalytic performance.Most importantly,PCNA@Fe SA can achieve power density of 514 m W cm^(-2) as cathodic catalyst in a PEMFC and discharge peak power density of 185 m W cm^(-2) in an alkaline Zn-air battery.The outstanding performance is derived from both the high specific surface area and high-density of iron single atom in nitrogen doped nanocubic carbon matrix. 展开更多
关键词 Gaseous doping Fe-Nx sites Fe single atoms Oxygen reduction reaction ELECTROCATALYSTS
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Microstructure and mechanical properties of friction pull plug welding for2219-T87 aluminum alloy with tungsten inert gas weld 被引量:2
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作者 Zhen Shao Lei Cui +4 位作者 lijun yang Peng Lu Huimiao Wang Zhuanping Sun Jianling Song 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2022年第6期1216-1224,共9页
The friction pull plug welding(FPPW)of the 2219-T87 tungsten inert gas(TIG)welded joint was investigated,and the microstructures,precipitate evolution,mechanical properties,and fracture morphologies of this joint were... The friction pull plug welding(FPPW)of the 2219-T87 tungsten inert gas(TIG)welded joint was investigated,and the microstructures,precipitate evolution,mechanical properties,and fracture morphologies of this joint were analyzed and discussed.In this study,defectfree joints were obtained using a rotational speed of 7000 r/min,an axial feeding displacement of 12 mm,and an axial force of 20-22 kN.The results indicated that within these welding parameters,metallurgical bonding between the plug and plate is achieved by the formation of recrystallized grains.The microstructural features of the FPPW joint can be divided into different regions,including the heat-affected zone(HAZ),thermomechanically affected zone(TMAZ),recrystallization zone(RZ),heat-affected zone in the TIG weld(TIG-HAZ),and the thermomechanically affected zone in the TIG weld(TIG-TMAZ).In the TIG-TMAZ,the grains were highly deformed and elongated due to the shear and the extrusion that produces the plug during the FPPW process.The main reason for the softening in the TMAZ is determined to be the dissolution ofθ’and coarsening ofθprecipitate particles.In a tensile test,the FPPW joint welded with an axial force of 22 kN showed the highest ultimate tensile strength of 237 MPa.The locations of cracks and factures in the TIG-TMAZ were identified.The fracture morphology of the tensile sample showed good plasticity and toughness of the joints. 展开更多
关键词 friction pull plug welding tungsten inert gas weld microstructures constituent particles mechanical properties
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First-principles study of catalytic activity of W-doped cobalt phosphide toward the hydrogen evolution reaction 被引量:2
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作者 Cehuang Fu Xiaohui Yan +4 位作者 lijun yang Shuiyun Shen Liuxuan Luo Guanghua Wei Junliang Zhang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第11期1698-1705,共8页
In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co at... In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co atoms that present the higher d band center are marked as valid sites,whereas the others are marked as invalid sites owing to their weaker H adsorption ability.It is further revealed that W-doping can decrease the d band center of the surface Co atoms,which is beneficial for the HER;however the exposure to W weakens the desorption of H.To address the strong adsorption effect of W,the doping sites and dopant content are analyzed,and the results indicate that 8.4 wt%W doping at the invalid surface Co sites is preferred;moreover,the optimal W content increases to 16.8 wt%when W is inserted into the subsurface.The effect of W doping is weakened when the doping site is far away from the surface. 展开更多
关键词 Hydrogen Evolution Reaction Density functional theory COP DOPING
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Characteristics of a plasma flow field produced by a metal array bridge foil explosion 被引量:2
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作者 Junying WU Long WANG +3 位作者 Yase LI lijun yang Manzoor SULTAN Lang CHEN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第7期127-138,共12页
To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren ph... To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha-Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet's center region sharply increase because of the superposition of plasma beams. 展开更多
关键词 array bridge foil electrical exploding PLASMA shock wave numerical simulation
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Simulation and Experimental Study on the Atomization Character of the Pressure-Swirl Nozzle 被引量:6
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作者 Jianbo Zhao lijun yang 《Open Journal of Fluid Dynamics》 2012年第4期271-277,共7页
In this paper the atomization character of the pressure-swirl injector was measured by using the Phase Doppler Particle Analyzer (PDPA) in the section of 150 mm below the outlet of the orifice. The orifice diameter of... In this paper the atomization character of the pressure-swirl injector was measured by using the Phase Doppler Particle Analyzer (PDPA) in the section of 150 mm below the outlet of the orifice. The orifice diameter of the pressure-swirl injector is 0.62 mm. The atomization character includes the spray angle, the water flow rate, the Sauter mean diameter (SMD), the velocity of the particles and their distribution in the radial and the axial directions under the pressure from 1 MPa to 4.5 MPa. After that the atomization character of the pressure-swirl injector was simulated in the DPM panel. The same atomization character of the injector was calculated and compared with the experimental data. The simulation was corrected by using the experimental data which can make it accurately and the model can be used to predict and calculate the atomization character of different injectors. 展开更多
关键词 ATOMIZATION SIMULATION PDPA
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HIV Vulnerability in Out-of-School Adolescents and Youth in Yunnan, China 被引量:1
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作者 Jianghong Li lijun yang +6 位作者 Zhouyang Ren Chongbin Mo Dingwen Chen Fuqiang Dai Mingzhong Jiang Zhijie Tang Peter Jacoby 《World Journal of AIDS》 2012年第2期48-56,共9页
This study investigated multiple aspects of vulnerability to HIV in out-of-school adolescents and youth in Yunnan Province, a high HIV risk region in China. The findings show that socially disadvantaged adolescents an... This study investigated multiple aspects of vulnerability to HIV in out-of-school adolescents and youth in Yunnan Province, a high HIV risk region in China. The findings show that socially disadvantaged adolescents and youth were overrepresented in the out-of-school young people in Yunnan. The out-of-school young people in Yunnan exhibited 1) limited knowledge about HIV transmission and prevention, 2) a high prevalence of unprotected sexual activity, 3) high exposure to illicit drugs and alcohol use and a high prevalence of drug use in themselves, and 4) limited access to health services. There is an indication of higher exposure to risk behaviours in the younger age group. The study population used multiple media, particularly television, internet and radio, to obtain information about HIV transmission and prevention, particularly in the younger age group. These media may be an effective way of reaching this population in future HIV education and prevention programs in the region. 展开更多
关键词 HIV/AIDS Education and PREVENTION VULNERABILITY Out-of-School Adolescents and YOUTH YUNNAN China
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Threshold of Soil pH for Occurrence of Tobacco Bacterial Wilt in Henan Province 被引量:1
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作者 Haitao Wang Haohao Hao +3 位作者 Xiaojing Xu Haitang Huang Xueli Song lijun yang 《Plant Diseases and Pests》 CAS 2021年第2期11-15,共5页
[Objective]The paper was to study the relationship between spatial distribution characteristics of soil p H and bacterial wilt in tobacco-growing area in Henan Province.[Method]The 21 tobacco-growing fields infected b... [Objective]The paper was to study the relationship between spatial distribution characteristics of soil p H and bacterial wilt in tobacco-growing area in Henan Province.[Method]The 21 tobacco-growing fields infected by bacterial wilt and 91 tobacco-growing fields with no cases were selected from Henan Province,and the pH of fields was determined.[Result]Bacterial wilt mainly occurred in the tobacco-growing fields in Luoshan,Pingqiao,Queshan,Biyang,Suiping,and Xiping,and the soil pH mainly ranged from 5.5 to 6.5(accounted for 84.75%of total surveyed tobacco fields);bacterial wilt had not been found in tobacco-growing fields in Tanghe,Zhengyang,Shangcai,Sheqi,Wuyang and Chenqu,and the soil pH mainly ranged from 6.5 to 7.0(accounted for 81.25%of total surveyed tobacco fields).There were significant differences in soil pH between the fields with and without bacterial wilt,and soil pH 6.5 could be regarded as the threshold for the occurrence of tobacco bacterial wilt in Henan Province.There was extremely significantly positive linear correlation between soil p H and latitude(y=0.7375 x-17.799,R2=0.386,P<0.01).The geographical boundary of soil pH 6.5 was roughly 33°N,and bacterial wilt was less likely to occur in the north tobacco-growing areas of the boundary.[Conclusion]The study will provide a scientific basis for the prevention and control of tobacco bacterial wilt in Henan. 展开更多
关键词 Soil pH Bacterial wilt TOBACCO HENAN
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Expression of hypoxia-inducible factor 1 alpha and oligodendrocyte lineage gene-1 in cultured brain slices after oxygen-glucose deprivation
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作者 Hong Cui Weijuan Han +1 位作者 lijun yang Yanzhong Chang 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第4期328-337,共10页
Oligodendrocyte lineage gene-1 expressed in oligodendrocytes may trigger the repair of neuronal myelin impairment, and play a crucial role in myelin repair. Hypoxia-inducible factor la, a transcription factor, is of g... Oligodendrocyte lineage gene-1 expressed in oligodendrocytes may trigger the repair of neuronal myelin impairment, and play a crucial role in myelin repair. Hypoxia-inducible factor la, a transcription factor, is of great significance in premature infants with hypoxic-ischemic brain damage There is little evidence of direct regulatory effects of hypoxia-inducible factor le on oligodendrocyte lineage gene-l. In this study, brain slices of Sprague-Dawley rats were cultured and subjected to oxygen-glucose deprivation. Then, slices were transfected with hypoxia-inducible factor la or oligodendrocyte lineage gene-1. The expression levels of hypoxia-inducible factor la and oligodendrocyte lineage gene-1 were significantly up-regulated in rat brains prior to transfection, as detected by immunohistochemical staining. Eight hours after transfection of slices with hypoxia-inducible factor la, oligodendrocyte lineage gene-1 expression was upregulated, and reached a peak 24 hours after transfection. Oligodendrocyte lineage gene-1 transfection induced no significant differences in hypoxia-inducible factor la levels in rat brain tissues with oxygen-glucose deprivation. These experimental findings indicate that hypoxia-inducible factor la can regulate oligodendrocyte lineage gene-1 expression in hypoxic brain tissue, thus repairing the neural impairment. 展开更多
关键词 neural regeneration brain injury biological factors hypoxia-inducible factor la oligodendrocyte lineage gene-1 oxygen-glucose deprivation brain slice culture immunohistochemistry OLIGODENDROCYTE myelin repair premature delivery rat grants-supported paper photographs-containing paper neuroregeneration
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Congestion Relief in Downlink OFDMA Cellular System Using Inter-Cell Relay
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作者 Weifeng Lu Mingqi Zhu +3 位作者 Jia Xu Siguang Chen lijun yang Jian Xu 《China Communications》 SCIE CSCD 2019年第4期35-46,共12页
This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighbori... This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighboring cells. It is shown that when using inter-cell relay, the number of calls in the congestion cell can be significantly increased. The congestion cell is divided into two parts. One is called non-relay area(NRA), in which a call directly communicates with the base station(BS) of a congested cell. The other is called relay area(RA), in which a call communicates with the BS of a neighboring cell through a relay station(RS). The two parts have different user-call densities. By adjusting the densities of two parts, we will maximize the number of supported calls inside a congested cell. The results show the benefits gained from inter-cell relay in congestion relief, which can reduce cell congestion by fully utilizing the available resources in the neighboring cells. 展开更多
关键词 OFDMA cellular system CONGESTION RELIEF optimization problem inter-cell RELAY
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