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Strengthening Mechanisms of 15 vol.% Al_(2)O_(3) Nanoparticles Reinforced Aluminum Matrix Nanocomposite Fabricated by High Energy Ball Milling and Vacuum Hot Pressing

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Acta Metallurgica Sinica(English Letters) 2022年第6期35卷 915-921页

作者： Ke zhao Zhongying Duan Jinling Liu Guozheng kang Linan An School of Mechanics and Engineering Southwest Jiaotong UniversityChengdu 610031China Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province Southwest Jiaotong UniversityChengdu 610031China Department of Materials Science and Engineering University of Central FloridaOrlandoFL 32816USA

Increasing nanoparticle volume fraction has been proved to be effective in improving the strength of nanoparticle reinforced Al matrix nanocomposite. However, the underlying mechanisms for the ultrahigh strength of those nanocomposites with high volume fraction(> 10 vol.%) nanoparticles are short of experimental research. In this study, the strengthening mechanisms of high strength Al matrix nanocomposite reinforced with 15 vol.% Al_(2)O_(3) nanoparticles were investigated experimentally and analyzed theoretically. The results show that the thermal mismatch induced geometrically necessary dislocations exhibit a negligible strengthening effect, because of their low density in the nanocomposite that is contradiction to the conventional dislocation punch model. Orowan mechanism makes a major strengthening contribution in view of the deformation process dominated by nanoparticle-dislocation interactions due to the extreme pinning effect of nanoparticles on dislocation motion. In addition, the several mechanisms including grain boundary strengthening, load transfer strengthening, and elastic modulus mismatch induced dislocation strengthening contribute to the strength increase.

关键词： Al matrix nanocomposite Strengthening mechanism Nanoparticle High volume fraction Microstructure

Educating for Wholeness, but Beyond Competences: Challenges to Key-Competences- Based Education in China

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ECNU Review of Education 2020年第3期3卷 470-487页

作者： kang zhao College of Education Zhejiang University

Purpose:This article aims to conduct a critical analysis of key-competences-based education in China today by revealing three main challenges that Chinese educational practitioners,researchers,and policymakers might ***/Approach/Methods:Against the backdrop of international and Chinese policy and the practice of key-competences-based education,this article focuses on a critical discourse analysis of this educational movement in ***:China places great emphasis on the personal,cultural,and moral dimensions in generating a framework of competences,paying considerable attention to the well-being of children;hence it currently endeavors to provide a consistent educational framework to educate the young for the all-round ***,three challenges are salient:the dilemma between Core-Suyang(Core-Competence)and the education for all-round development of the young,the limitations of design of“subject core-competences,”and a lack of consideration of subjectification as purpose of ***/Value:Education which merely focuses on a list of key-competences might not only exclude non-key-competences but also exclude something unforeseen and unknown in the process of educational *** is therefore suggested that a holistic education needs to be engaged in with an encompassing and dynamic view of purpose(s)of education,in which the education for subjectification is at stake in our educational endeavor.

关键词： Curriculum key-competences purpose of education subjectification subjectivity wholeness

Cognitive disorder and changes in cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor following brain injury

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Neural Regeneration Research 2008年第3期3卷 305-308页

作者： Weiliang zhao Dezhi kang Yuanxiang Lin Department of Neurosurgery First Hospital Affiliated to Fujian Medical University Fuzhou 350005 Fujian Province China

BACKGROUND： Learning and memory damage is one of the most permanent and the severest symptoms of traumatic brain injury; it can seriously influence the normal life and work of patients. Some research has demonstrated that cognitive disorder is closely related to nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor. OBJECTIVE： To summarize the cognitive disorder and changes in nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor following brain injury. RETRIEVAL STRATEGY： A computer-based online search was conducted in PUBMED for English language publications containing the key words ＂brain injured, cognitive handicap, acetylcholine, N-methyl-D aspartate receptors, neural cell adhesion molecule, brain-derived neurotrophic factor＂ from January 2000 to December 2007. There were 44 papers in total. Inclusion criteria： ① articles about changes in nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor following brain injury; ② articles in the same researching circle published in authoritative journals or recently published. Exclusion criteria： duplicated articles. LITERATURE EVALUATION： References were mainly derived from research on changes in these four factors following brain injury. The 20 included papers were clinical or basic experimental studies. DATA SYNTHESIS： After craniocerebral injury, changes in these four factors in brain were similar to those during recovery from cognitive disorder, to a certain degree. Some data have indicated that activation of nicotine cholinergic receptors, N-methyl-D aspartate receptors, neural cell adhesion molecule, and brain-derived neurotrophic factor could greatly improve cognitive disorder following brain injury. However, there are still a lot of questions remaining; for example, how do these fac

关键词： brain injured cognitive handicap acetylcholine N-methyl-D aspartate receptors neural cell adhesion molecule brain-derived neurotrophic factor

Surface Temperature Change of U75V 60 kg/m Heavy Rail During Heat Treatment

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Journal of Iron and Steel Research International 2013年第2期20卷 33-37,67页

作者： kang Hao WU Di zhao Xian-ming State Key Laboratory of Rolling and Automation Northeastern University

The U75V 60 kg/m heavy rail samples were heated to 900 ℃ in a resistance furnace for a fixed duration of 50 min. Under this condition, the samples were austenitized totally. Then, the samples were dragged out of furnace and cooled for 25 s in the open air. After that, the samples entered into the air spraying channel, and were cooled from the top and both sides by compressed air. During this period, main technical parameters were changed such as the distance between spray nozzles and surface of rail head, air pressure, air spraying time and air temperature. So under laboratory condition, optimal heat-treating parameters of U75V 60 kg/m heavy rail were determined as the distance between spray nozzles and surface of rail head of 15 mm, air pressure of 0.26 MPa, cooling time of 80 s, and air temperature of 28 ℃. The surface temperature at different positions of heavy rail was measured before and after heat treatment, and the temperature changing law was determined. The self tempering occurred on the surface of rail head after heat treatment, and the tempering temperature became the largest （about 3 min） after heat treatment, separately 528, 524 and 536 ℃ at the center, top fillet and bottom fillet of rail head. The heavy rail was cooled in open air after heat treatment; during this period, the temperature gap on the surface of heavy rail became smaller and smaller, and was reduced to zero when being cooled for 20 min.

关键词： temperature change heavy rail heat treatment

Long range trans-Pacific transport and deposition of Asian dust aerosols

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Journal of Environmental Sciences 2008年第4期20卷 424-428页

作者： HAN Yongxiang FANG Xiaomin zhao Tianliang kang Shichang Lanzhou Arid Meteorological Institute and Key Laboratory of Arid Climatic Change and Reducing Disaster China Meteorological Administration Lanzhou 730020 China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China Air Quality Research Branch Meteorological Service of Canada Toronto Ontario m3H 5T4 Canada

The deposition of Asian dust aerosols during their trans-Pacific transport might cause significant marine phytoplankton biomass increases. However, the knowledge of the trans-Pacific dust transport, deposition, and spatial distribution is still poor due to a lack of continuous and simultaneous observations in the Asian subcontinent, the north Pacific Ocean, and North America. The severe Asian dust storm during 6 to 9 April 2001 provided an opportunity to gain a better understanding of trans-Pacific dust transport and deposition, using a comprehensive set of observations from satellites, ground-based light detection and ranging, aircraft, and surface observation networks. The observations and model simulations outline the general pattern of dust transport, deposition, vertical profile, and spatial distribution. The following points were observed：（1） the surface dust concentrations decreased exponentially with the increasing dust transport distance from 80°E to 120°W along the transport pathway; （2） the altitude of the dust concentration peak increased with increasing transport distance in the north Pacific region; and （3） the spatial distribution of dust deposition mainly depended on the trans-Pacific transport route.

关键词： dust aerosol trans-Pacific dust transport and deposition spatial distribution

Two-order Hermite vector-interpolating subdivision schemes

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第9期7卷 1566-1571页

作者： FAN Min kang Bao-sheng zhao Hua Beijing Institute of Tracking and Telecommunication Technology Beijing 100094 China Department of Computer Sctence Northwest University Xi＇an 710069 China

A family of two-order Hermite vector-interpolating subdivision schemes is proposed and its convergence and con- tinuity are analyzed. The iterative level can be estimated for given error. The sufficient conditions of C2 continuity are proved. Geometric features of subdivision curves, such as line segments, cusps and inflection points, are obtained by appending some conditions to initial vectorial Hermite sequence. An algorithm is presented for generating geometric features. For an initial se- quence of two-order Hermite elements from unit circle, the numerical error of the 4th subdivided level is O(10?4).

关键词： Two-order vectorial Hermite element Hermite-interpolating subdivision schemes Geometric features

Finite Element Analysis of the Steel Reinforced Plastic Pipe

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Journal of Materials Science & Technology 2003年第Z1期19卷 43-45页

作者： Hongyi SUN Wenqi MA Dachang kang Keding zhao Harbin University of Science and Technology Harbin 150080 China Daqing Oilfields Postdoctoral Workstation Daqing 163453 China Harbin Institute of Technology Harbin 150001 China Daqing Oilfields Postdoctoral Workstation Daqing 163453 China Harbin Institute of Technology Harbin 150001 China Harbin Institute of Technology Harbin 150001 China

The steel reinforced plastic pipe is a kind of green environmental protection pipelines with double-sides corrosionresisting and better withstanding to medium working pressure. The structure and technical process of this pipe are described briefly in this paper, and the finite element analysis has been done for the sake of understanding the distributions of stress and displacement inside this pipe under hydrostatic pressure. The analysis results are very important for safety application of the steel reinforced plastic pipe.

关键词： Steel reinforced plastic pipe, Finite element analysis

Balancing Carbon Emission Reductions and Social Economic Development for Sustainable Development: Experience from 24 Countries

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Chinese Geographical Science 2020年第3期30卷 379-396页

作者： kang Meimei zhao Wenwu JIA Lizhi LIU Yanxu State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal Univer-sityBeijing 100875China Institute of Land Surface System and Sustainable Development Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China

The impact of human carbon emissions on climate has generated widespread global concern. We selected 24 countries as research objects and analysed the changes in carbon emissions in different countries between the establishment of emission reduction actions in 1990 and 2014. Then, we selected 19 factors representing four categories(economy, population, technology and energy) to explore the key factors that led to changes in carbon dioxide(CO2) emissions in different countries. Emission reduction actions since 1990 did not lead to marked improvements, and only five countries(Russia, Germany, the United Kingdom, Italy and France) achieved reductions in carbon emissions. The factors that influenced CO2 emissions varied among countries. In most developing countries, reductions in CO2 emissions were caused by reductions in poverty and inherent natural conditions. Moreover, the extent of influence of a given factor on CO2 emissions differed among countries. The global economic crisis may cause similar fluctuations in CO2 emissions in many countries. Adjustments to energy and industrial structures are the main reason for the reduction in carbon emissions, whereas economic growth and urbanization are the two major contributors to the growth of carbon emissions. According to historical carbon emissions data, a green energy revolution must be implemented to address global climate change and ensure the sustainable development of human societies.

关键词： carbon dioxide(CO2)emissions climate change economic growth sustainable development

Searching for ^(76)Ge neutrinoless double beta decay with the CDEX-1B experiment

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Chinese Physics C 2024年第10期48卷 11-22页

作者： Bing-Tao Zhang Jun-Zheng Wang Li-Tao Yang Qian Yue Ke-Jun kang Yuan-Jing Li Hai-Peng An C.Greeshma Jian-Ping Chang Yun-Huan Chen Jian-Ping Cheng Wen-Han Dai Zhi Deng Chang-Hao Fang Xin-Ping Geng Hui Gong Qiu-Ju Guo Xu-Yuan Guo Li He Sheng-Ming He Jin-Wei Hu Han-Xiong Huang Tu-Chen Huang Hai-Tao Jia Xi Jiang S.Karmakar Hao-Bin Li Jian-Min Li Jin Li Qian-Yun Li Ren-Ming-Jie Li Xue-Qian Li Yu-Lan Li Yi-Fan Liang Bin Liao Fong-Kay Lin Shin-Ted Lin Jia-Xuan Liu Shu-Kui Liu Yan-Dong Liu Yu Liu Yuan-Yuan Liu Zhong-Zhi Liu Hao Ma Yu-Cai Mao Qi-Yuan Nie Jin-Hua Ning Hui Pan Ning-Chun Qi Jie Ren Xi-Chao Ruan Ze She Manoj Kumar Singh Tian-Xi Sun Chang-Jian Tang Wei-You Tang Yang Tian Guang-Fu Wang Li Wang Qing Wang Yu-Feng Wang Yun-Xiang Wang Henry-Tsz-King Wong Shi-Yong Wu Yu-Cheng Wu Hao-Yang Xing Rui Xu Yin Xu Tao Xue Yu-Lu Yan Nan Yi Chun-Xu Yu Hai-Jun Yu Jian-Feng Yue Ming Zeng Zhi Zeng Feng-Shou Zhang Lei Zhang Zhen-Hua Zhang Zhen-Yu Zhang kang-kang zhao Ming-Gang zhao Ji-Fang Zhou Zu-Ying Zhou Jing-Jun Zhou Key Laboratory of Particle and Radiation Imaging(Ministry of Education)and Department of Engineering Physics Tsinghua UniversityBeijing 100084 Department of Physics Tsinghua UniversityBeijing 100084 Institute of Physics Academia SinicaTaipei 11529 NUCTECH Company Beijing 100084 YaLong River Hydropower Development Company Chengdu 610051 College of Nuclear Science and Technology Beijing Normal UniversityBeijing 100875 College of Physics Sichuan UniversityChengdu 610065 School of Physics Peking UniversityBeijing 100871 Department of Nuclear Physics China Institute of Atomic EnergyBeijing 102413 Sino-French Institute of Nuclear and Technology Sun Yat-sen UniversityZhuhai 519082 School of Physics Nankai UniversityTianjin 300071 Department of Physics Banaras Hindu UniversityVaranasi 221005 Department of Physics Beijing Normal UniversityBeijing 100875

We operated a p-type point contact high purity germanium(PPCGe)detector(CDEX-1B,1.008 kg)in the China Jinping Underground Laboratory(CJPL)for 500.3 days to search for neutrinoless double beta(0νββ)decay of ^(76)Ge.A total of 504.3 kg⋅day effective exposure data was *** anti-coincidence and the multi/single-site event(MSE/SSE)discrimination methods were used to suppress the background in the energy region of interest(ROI,1989–2089 keV for this work)with a factor of 23.A background level of 0.33 counts/(keV⋅kg⋅yr)was *** lower limit on the half life of^(76)Ge 0νββdecay was constrained as T_(1/2)^(0ν)>1.0×10^(23)yr(90%C.L.),corresponding to the upper limits on the effective Majorana neutrino mass:<3.2–7.5 eV.

关键词： neutrinoless double beta decay CDEX point-contact germanium detector ^(76)Ge