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Graphs Whose Critical Groups Have Larger Rank

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Acta Mathematica Sinica,English Series 2011年第9期27卷 1663-1670页

作者： yao ping hou Wai Chee SHIU Wai Hong CHAN Departement of Mathematics Hu'nan Normal University Changsha 410081 P. R. China Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong P. R. China

The critical group C（G） of a graph G is a refinement of the number of spanning trees of the graph and is closely connected with the Laplacian matrix. Let r（G） be the minimum number of generators （i.e., the rank） of the group C（G） and β（G） be the number of independent cycles of G. In this paper, some forbidden induced subgraphs axe given for r（G） = n - 3 and all graphs with r（G） = j3（G） = n - 3 are characterized

关键词： Critical group of a graph Laplacian matrix Smith normal form

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具有斜特征值互逆性质的单圈图

数学学报（中文版） 2014年第4期57卷 657-664页

作者：侯耀平方爱香湖南第一师范学院数学系长沙410205 湖南师范大学数学系长沙410081

设G是一个无向图.如果对G的任一(某个)定向图G,G的斜邻接矩阵S(G)的每一个特征值λ,其倒数1/λ同样也是S(G)的特征值,且重数与λ相同,就称G是具有强迫(允许)斜特征值互逆性质.本文确定了所有具有强迫(允许)斜特征值互逆性质的单圈图.

关键词：单圈图定向图图谱特征值互逆性质

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大型水轮发电机在各种工况下的端部磁场计算

上海交通大学学报 2002年第2期36卷 234-236,242页

作者：姚若萍侯小全饶芳权上海交通大学电力学院上海200030 东方电机股份有限公司四川德阳618000

考虑水轮发电机端部结构的特点 ,计入材料的各向异性和非线性 ,以电路和磁路等效原理导出定子铁芯叠片边段和分瓣压圈的等效电导率及磁导率 .计算了一台 72 .5 MW水轮发电机在各种工况下的端部磁场 ,结果与实测值非常吻合 ,证明了所提... 详细信息

考虑水轮发电机端部结构的特点 ,计入材料的各向异性和非线性 ,以电路和磁路等效原理导出定子铁芯叠片边段和分瓣压圈的等效电导率及磁导率 .计算了一台 72 .5 MW水轮发电机在各种工况下的端部磁场 ,结果与实测值非常吻合 ,证明了所提出方法的正确性 .计算了李家峡40 0 MW水轮发电机在欠励工况下的端部磁场 ,并与现场进相工况运行时的实测数据对比 ,结果满足工程要求 ,为预测水轮发电机进相能力和充电容量提供了依据 .

关键词：大型水轮发电机端部磁场计算各向异性欠励工况

Unveiling the promotion role of ZnO on Zn-Al spinel oxide for CO2 hydrogenation

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Journal of Energy Chemistry 2025年第1期 18-25页

作者： Tongyao Wang Xinlong yao Lixin Liang Hongyu Chen Pan Gao Guangjin hou State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

The Zn-Al spinel oxide stands out as one of the most active catalysts for high-temperature methanol synthesis from CO2hydrogenation. However, the structure–activity relationship of the reaction remains poorly understood due to challenges in atomic-level structural characterizations and analysis of reaction intermediates. In this study, we prepared two Zn-Al spinel oxide catalysts via coprecipitation（ZnAl-C）and hydrothermal（ZnAl-H） methods, and conducted a comparative investigation in the CO2hydrogenation reaction. Surprisingly, under similar conditions, ZnAl-C exhibited significantly higher selectivity towards methanol and DME compared to ZnAl-H. Comprehensive characterizations using X-ray diffraction（XRD）, Raman spectroscopy and electron paramagnetic resonance（EPR） unveiled that ZnAl-C catalyst had abundant ZnO species on its surface, and the interaction between the ZnO species and its ZnAl spinel oxide matrix led to the formation of oxygen vacancies, which are crucial for CO2adsorption and activation. Additionally, state-of-the-art solid-state nuclear magnetic resonance（NMR） techniques,including ex-situ and in-situ NMR analyses, confirmed that the surface ZnO facilitates the formation of unique highly reactive interfacial formate species, which was readily hydrogenated to methanol and DME. These insights elucidate the promotion effects of ZnO on the ZnAl spinel oxide in regulating active sites and reactive intermediates for CO2-to-methanol hydrogenation reaction, which is further evidenced by the significant enhancement in methanol and DME selectivity observed upon loading ZnO onto the ZnAl-H catalyst. These molecular-level mechanism understandings reinforce the idea of optimizing the ZnO-ZnAl interface through tailored synthesis methods to achieve activity-selectivity balance.

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Analysis of blade vibration response induced by rotating stall in axial compressor

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航空动力学报 2012年第10期27卷 2269-2277页

作者： Zhang, Ming-Ming hou, An-ping Li, Jian-Xiong yao, Juan Chen, Ying-Xiu School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100191 China

An experimental and numerical study was conducted to investigate the forced response of blade vibration induced by rotating stall in a low speed axial *** have been made of the transient stalling process in a low speed axial compressor *** CFD study was performed using solution of 3-dimensional Navier-Stokes equations,coupled with structure finite element models for the blades to identify modal shapes and structural deformations *** between fluid and structure were managed in a coupled manner,based on the interface information exchange until convergence in each time *** on the rotating stall measurement data obtained from a low speed axial compressor,the blade aeroelastic response induced by the rotating stall flow field was analyzed to study the vibration characteristics and the correlation between the *** this approach,good agreement between the numerical results and the experimental data was *** flow phenomena were well captured,and the results indicate that the rotating field stall plays a significant role in the blade vibration and stress affected by the flow excitation.

关键词： compressor rotating stall blade forced response CFD fluid-structure interaction

Climate change has more adverse impacts on the higher mountain communities than the lower ones: people’s perception from the northern Himalayas

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Journal of Mountain Science 2019年第11期16卷 2625-2639页

作者： HUANG Xiao-hui Zhou yao-zhi FANG Jiang-ping hou Lei Tibet Agriculture&Animal Husbandry University Linzhi 8600China Research Institute of Tibet Plateau Ecology Tibet Agriculture&Animal Husbandry UniversityLinzhi 8600China United Key Laboratories of Ecological Security Tibet Autonomous RegionLinzhi 8600China Resources&Environment College Tibet Agriculture&Animal Husbandry UniversityLinzhi 8600China

The Himalayas are assumed to experience rapid climate change,with serious environmental,social and economic consequences for people living in and around the mountain ***,the extent of climate change and its impact on the region are underexplored,especially on northern slope of the *** on local knowledge,we report perceived changes in climate and consequences of such changes for natural andsocial *** respondents in this study were distributed at a continuous elevation gradient of 3570-4646 m above sea level in the northern ***,it is possible to analyze the process of the shift of bioclimate zones under climate change and the differences in climate change effects cross *** those in the pastoral area(Zhegu town)with an altitude of 4600 m,91.2%(n=114)of the respondents believe that the climate is obviously changing;the ratio of reporting rainfall decreasing is 77.2%(n=114);those who perceive delayed rainy season,and increased climate change-related natural disasters account for 38.9%(n=113),72.8%(n=103),respectively;more than two thirds(70.3%)(n=111)view drought as the biggest challenge to address climate change,and more than half(59.3%)(n=113)of the respondents believe that the impact of climate change is mainly *** these data rank first among the four survey areas(Zhegu town/pastoral region,Nedong County/crop growing regions,Zhanang County/crop growing region and Nagarze County/farming-pastoral region).Due to climate warming,Labidura riparia spreads to a higher altitude in the basins in Nedong County(Shannan City,Tibet)and Zhanang County(Shannan City,Tibet)at the rate of 31.1±6.4 m/a and 46.7±8.8 m/a,respectively in *** of the respondents view the natural variability as the main cause of climate changes,only 10.7%-29.0%among them view human activities as the main *** challenges for local people to address climate change include droughts and economic *** local perceptions conf

关键词： Northern Himalayan Climate change Perception Elevation gradient Tibet

Hydrogen absorption behavior of TA15 alloy

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 210-215页

作者： Xue-ping Ren Fang-fang Zhang Qing-miao Guo Hong-hang hou yao-qi Wang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Zhejiang Special Equipment Inspection and Research Institute Hangzhou 310015 China General Research Institute for Nonferrous Metals Beijing 100088 China Beijing Aeronautical Manufacturing Technology Research Institute Beijing 100024 China

The hydrogen absorption kinetics of TA15 titanium alloy at 973-1123 K was studied using a tube-type hydrogen treatment furnace. The hydrogen absorption kinetic curves obtained were analyzed according to a series of mechanism equations to reveal the kinetic parameters and mechanism of the hydrogen absorption process. The results show that both the hydrogen absorption rate and the equilibrium hydrogen pressure increase and the time to reach equilibrium is shortened with increasing temperature. It is found that only the second hydrogen absorption period exists in the hydrogen absorption process of TA15 alloy between 973 and 1123 K, and the activation energy is 54.889 kJ/mol for hydrogen absorption. X-ray diffraction （XRD） and scanning electron microscopy （SEM） results demonstrate that δ hydride forms between 973 and 1123 K, and β phase decreases with the increase of temperature. Orthorhombic α＂ martensite is generated at 1073-1123 K, and their amount increases with increasing temperature.

关键词： titanium alloy kinetics activation energy microstructure

Studyon Evaluation Methods for Lateral Stability of High-Speed Trains

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中国铁道科学 2012年第6期33卷 132-139页

作者： yao Jianwei SUN Lixia hou Fuguo Railway Science and Technology Research and Development Center China Academy of Railway Sciences Beijing 100081 China

Taking a high-speed train in China as an example,using computer simulation technology and comparing with the test data,the three current methods including linear stability analysis method,nonlinear stability analysis method and the field testing criterion are studied to evaluate stability of high-speed trains.A new stability evaluation method is proposed which can be used to evaluate lateral stability of high-speed vehicle based on the codes of UIC 515and UIC *** the viewpoint of taking the most unfavorable track conditions into account and improving the safety margin,the new method uses the root mean square of bogie lateral acceleration as a criterion to evaluate the lateral stability of high-speed *** example shows that the proposed method not only considers the forced vibration caused by track irregularities in the actual practice,but also takes the instability self-excited vibration into account,so it can realize early warning of bogie slight unstable oscillation,meanwhile the method itself does not involve complex algorithms which has the possibility of engineering applications.

关键词： High-speed train Lateral stability Critical speed Evaluation method

Severe Type of COVID-19:Pathogenesis,Warning Indicators and Treatment

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Chinese Journal of Integrative Medicine 2022年第1期28卷 3-11页

作者： SHI Ke LIU yao ZHANG Qun RAN Chong-ping hou Jie ZHANG Yi WANG Xian-bo Center of Integrative Medicine Beijing Ditan HospitalCapital Medical UniversityBeijing(100015)China Department of Gastroenterology Dongzhimen HospitalBeijing University of Chinese MedicineBeijing(100007)China

Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2,is a major public health *** epidemic is unlikely to be contained until the global launch of safe and effective vaccines that could prevent serious illnesses and provide herd *** most patients have mild flu-like symptoms,some develop severe illnesses accompanied by multiple organ *** identification of pathophysiology and early warning biomarkers of a severe type of COVID-19 contribute to the treatment and prevention of serious ***,we review the pathophysiology,early warning indicators,and effective treatment of Chinese and Western Medicine for patients with a severe type of COVID-19.

关键词： coronavirus disease 2019 pathogenesis indicators treatment Chinese medicine