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Some ＊-Clean Group Ringst

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Algebra Colloquium 2015年第1期22卷 169-180页

作者： yanyan gao Jianlong Chen Yuanlin Li Department of Mathematics Southeast University Nanjing 210096 China Department of Mathematics and Physics Nanjing Institute of Technology Nanjing 211167 China Department of Mathematics Brock University St. Catharines L2S 3A1 Canada

A ring with involution ＊ is called ＊-clean if each of its elements is the sum of a unit and a projection. It is obvious that ＊-clean rings are clean. Vas asked whether there exists a clean ring with involution that is not ＊-clean. In this paper, we investigate when a group ring RG is ＊-clean, where ＊ is the classical involution on RG. We obtain necessary and sufficient conditions for RG to be ＊-clean, where R is a commutative local ring and G is one of the groups C3,C4, S3 and Q8. As a consequence, we provide many examples of group rings which are clean but not ＊-clean.

关键词： group ring clean ring,*-clean ring

New insight into effect of potential on degradation of Fe-N-C catalyst for ORR

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Frontiers in Energy 2021年第2期15卷 421-430页

作者： yanyan gao Ming HOU Manman QI Liang HE Haiping CHEN Wenzhe LUO Zhigang SHAO Fuel Cell System and Engineering Laboratory Key Laboratory of Fuel Cells&Hybrid Power SourcesDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

In recent years,Fe-N-C catalyst is particularly attractive due to its high oxygen reduction reaction(ORR)activity and low cost for proton exchange membrane fuel cells(PEMFCs).However,the durability problems still pose challenge to the application of Fe-N-C *** considerable work has been done to investigate the degradation mechanisms of Fe-N-C catalyst,most of them are simply focused on the active-site decay,the carbon oxidation,and the demetalation *** fact,the 2e−pathway in the ORR process of Fe-N-C catalyst would result in the formation of H2O2,which is proved to be a key degradation *** this paper,a new insight into the effect of potential on degradation of Fe-N-C catalyst was provided by quantifying the H2O2 *** this case,stability tests were conducted by the potential-static method in O2 saturated 0.1 mol/L *** the tests,H2O2 was quantified by rotating ring disk electrode(RRDE).The results show that compared with the loading voltage of 0.4 V,0.8 V,and 1.0 V,the catalysts being kept at 0.6 V exhibit a highest H2O2 *** is found that it is the combined effect of electrochemical oxidation and chemical oxidation(by aggressive radicals like H2O2/radicals)that triggered the highest H2O2 release rate,with the latter as the major cause.

关键词： proton exchange membrane fuel cells(PEMFCs) oxygen reduction reaction(ORR) Fe-N-C catalyst potential H2O2 degradation

Influence of International Openness on Corporate Environmental Performance in China

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China & World Economy 2011年第2期19卷 77-92页

作者： Maoliang Bu Zhibiao Liu yanyan gao Assistant Professor School of Business Nanjing University Nanjing China. Email: bumaoliang@*** Professor School of Economics Nanjing University Nanjing China. Email: zbliu@*** Postdoctor School of Economics and Management Southeast University Nanjing China. Email: adamesky@***.

This paper examines how international openness influences China＇s corporate environmental performance. A unique firm-level dataset is constructed by combining two databases： the Annual Industrial Survey and the China Green Watch Program Rating System. The empirical results obtained from a series of ordered probit models indicate that openness has a positive relation to corporate environmental performance in China. However, the two main market- opening strategies in China, exporting and attracting foreign investment, have different effects on environmental performance. The results reveal that foreign investment plays a substantial andpositive role that can support the environmental spillovers in China. However, the effect of exporting is insignificant. The environmental pressure from foreign customers to improve Chinese firms＇ environmental performance presents a challenge. Our study indicates that China could make environmental quality improvements through increased international openness, as is likely the case for other developing countries.

关键词： corporate environmental performance export foreign investment international openness

A new insight into the stability of nanofiber electrodes used in proton exchange membrane fuel cells

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Journal of Energy Chemistry 2020年第3期29卷 126-132页

作者： yanyan gao Ming Hou Liang He Manman Qi Haiping Chen Shaojing Hong Yongyi Jiang Zhigang Shao Baolian Yi Dalian National Laboratory for Clean Energy Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina University of Chinese Academy of Sciences Beijing 100039China Guangzhou Automobile Group Co.Ltd. Automotive Engineering InstituteGuangzhou 510080GuangdongChina Anhui Mingtian Hydrogen Energy Technology Co.Ltd. Lu’an 237000AnhuiChina

The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport ***,for the first time our research determined that the nanofiber electrodes were restricted by the poor chemical stability of the polymer *** gain further insight into the durability of nanofiber electrodes,both cyclic voltammetry aging tests and Fenton’s tests were *** to previous reports,our research demonstrated that nanofiber electrodes showed remarkable stability in the cyclic voltammetry aging ***,Fenton’s tests indicated that nanofibers in the electrodes would decompose easily while being attacked by reactive oxygen species such as HO·or HOO·,which greatly limits their practicability and *** different performances under the two tests also demonstrated that the cyclic voltammetry aging protocols,which have been applied extensively,cannot well mirror the real operating conditions of fuel cells.

关键词： PEMFC Nanofiber electrode Stability

Spatial Allocation of Urban Medical Facilities for the Elderly in China: With Hefei City as Example

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China City Planning Review 2019年第3期28卷 6-17页

作者： gao yanyan Li Zao Zhu gaoli Zheng Zhi College of Architecture&Art Hefei University of TechnologyHefeiP.R.China College of Architecture&Art Hefei University of TechnologyHefeiP.R.China Liuhe Town Government TaicangP.R.China China Water Huaihe Planning Design and Research Co. Ltd.HefeiP.R.China

The severe situation of a constantly growing aging population has brought along great challenges to the development of China’s medical and health undertakings. From the perspective of fairness, this paper discusses the rationality of the spatial allocation of medical facilities in the urban area of Hefei, considering the elderly’s demand through accessibility analysis. In term of medical facilities distribution, the 10-minute pedestrian accessible area of all medical facilities for the elderly is far from evenly covering the city’s urban area. The areas of high coverage rate concentrate within the Second Ring Road and aggregate in the sub-centers of the city as well. While in the fringe areas far away from the city center in the direction of the sub-city centers, which are undergoing the anti-aggregation of the elderly, the coverage rate of medical facilities is quite low. In term of medical facilities capacity(i.e., number of beds), there exits also an imbalance, with some facilities facing a serious shortage of beds, while some others seeing a remarkable surplus of beds supply. Under the premise of not adding any new medical facilities, a rational coordination of related service among different areas of the city based on the actual distribution of the elderly would be an effective measure to achieve a balance between supply and demand.

关键词： medical facility spatial allocation the elderly accessibility fairness

KSHV strategies for host dsDNA sensing machinery

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Virologica Sinica 2016年第6期31卷 466-471页

作者： Hang gao yanyan Song Chengrong Liu Qiming Liang Department of Nephrology The Second Hospital of Jilin University Changchun 130041 China

The innate immune system utilizes pattern recognition receptors cyclic GMP-AMP synthase(cGAS)to sense cytosolic double-stranded(ds) DNA and initiate type 1 interferon signaling and autophagy pathway, which collaborate to limit pathogen infections as well as alarm the adaptive immune response. The genomes of herpesviruses are large dsDNA, which represent a major class of pathogen signatures recognized by cellular DNA sensor cGAS. However, to successfully establish the persistent infection, herpesviruses have evolved their viral genes to modulate different aspects of host immune signaling. This review summarizes the evasion strategies of host cGAS DNA sensing pathway by Kaposi's Sarcoma-associated Herpesvirus(KSHV) and their contributions to KSHV life cycles.

关键词： dsDNA interferon innate autophagy signaling modulate pathogen alarm initiate contributions

Analysis of PbS/CdS:Bi and PbS/CdS:Ag Quantum Dot Solar Cells Internal Electronic Transmission

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Analysis of PbS/CdS:Bi and PbS/CdS:Ag Quantum Dot Solar Cell...

基于改进主动轮廓模型的无人机影像矿区地裂缝提取

2014中国功能材料科技与产业高层论坛

作者： Lin Li Xiaoping Zou yanyan gao Gongqing Teng Research Center for Sensor Technology.Beijing Key Laboratory for sensor.Ministry-of Education Key Laboratory for Modern Measurement and Control Technology.School of Applied Sciences.Beijing Information Science and Technology University.Jianxiangqiao Campus

To understand doped PbS/CdS:X（Bi,Ag）quantum dot better and how to choose appropriate doped elements,it’s necessary to analyze internal electronic transmission of doped quantum *** CdS（PbS/CdS:X）with elements of Bi and Ag,we characterized the photoanode by relatively detailed measurements and discussed the properties of PbS/CdS:Bi and PbS/CdS:Ag quantum dot solar cells assembled by photoanode materials,we have now analyzed the photoanode material more intuitively,explored more internal electronic transmission of doped quantum dot sensitized solar cell and also obtained a better power photoelectric conversion efficiency of2.52%by doped Bi.

关键词： dop PbS/CdS:Bi Pb/CdS:Ag quantum dot solar cell internal electronic transmission

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地球信息科学学报 2022年第12期24卷 2448-2457页

作者：郝明林惠晶高彦彦中国矿业大学江苏省资源环境信息工程重点实验室徐州221116 中国矿业大学环境与测绘学院徐州221116 航天宏图信息技术股份有限公司武汉430010

矿区地裂缝精准识别对防灾、减灾和生态环境修复具有重要意义。针对高分辨率无人机影像较难自动精确提取地裂缝的问题,本文提出了一种基于改进主动轮廓模型的无人机影像矿区地裂缝提取方法。首先,采用Otsu算法计算背景和地裂缝初值作为... 详细信息

矿区地裂缝精准识别对防灾、减灾和生态环境修复具有重要意义。针对高分辨率无人机影像较难自动精确提取地裂缝的问题,本文提出了一种基于改进主动轮廓模型的无人机影像矿区地裂缝提取方法。首先,采用Otsu算法计算背景和地裂缝初值作为先验知识;其次,构建背景和地裂缝初值的提取能量函数,并引入到传统CV主动轮廓模型,增强地裂缝提取的针对性;最后,通过轮廓的不断演化实现地裂缝的提取。以内蒙古扎赉诺尔矿区为研究区、无人机影像为数据源,采用改进主动轮廓模型方法进行地裂缝提取,并与传统的Canny边缘检测算法、支持向量机(SVM)、最大似然(MLM)和传统CV主动轮廓模型方法进行对比分析。结果表明:在地物类型较为单一的小范围区域,传统的Canny边缘检测算法和传统CV主动轮廓模型提取效果较差,改进主动轮廓模型、SVM和MLM共3种方法均可以取得较好的效果,其中,改进主动轮廓模型方法精度最高;在地物类型相对复杂的大范围区域,传统的Canny边缘检测算法、SVM、MLM和传统CV主动轮廓模型方法存在较多的漏提和误提,Kappa系数均低于0.7,而本文改进主动轮廓方法依然可以取得较好的效果,Kappa系数达到0.9左右。因此,本文提出的方法通过引入先验知识可有效提高地裂缝提取的精度和稳定性。

关键词：地裂缝 Otsu算法先验知识主动轮廓模型无人机影像矿区地物类型稳定性

学校教育投资、家庭内知识外部性与农户收入回报:来自苏北农村的证据

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南方经济 2009年第9期38卷 13-26页

作者：高彦彦南京大学经济学院产业经济学系

本文运用苏北农村农户层面的微观数据,并结合农业生产和农户家庭特征,来估计农民的教育回报率。农户以家庭为单位进行联合劳动的特征导致农户收入贡献的不可分性以及家庭内教育投资具有正的外部性,使得个人教育投资回报小于家庭回报。然... 详细信息

本文运用苏北农村农户层面的微观数据,并结合农业生产和农户家庭特征,来估计农民的教育回报率。农户以家庭为单位进行联合劳动的特征导致农户收入贡献的不可分性以及家庭内教育投资具有正的外部性,使得个人教育投资回报小于家庭回报。然而,由于家庭内部更多成员的教育投资的外部性具有递减的特征以及婚姻市场存在的匹配现象,可能会出现由知识拥挤带来的教育投资过度问题。本文的实证分析表明:农户家庭内成员的教育投资的确存在外部性;教育投资回报会随着受教育人数的增加而减少;农村婚姻中存在教育匹配效应;户主配偶的教育投资存在动态不足。

关键词：教育投资收入回报知识外部性不可分性婚姻匹配