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Supersonic swirling characteristics of natural gas in convergent-divergent nozzles

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Petroleum Science 2011年第1期8卷 114-119页

作者： Wen Chuang Cao Xuewen yang yan zhang Jing Department of Oil and Gas Engineering China University of PetroleumQingdaoShandong 266555China

The supersonic nozzle is a new apparatus which can be used to condense and separate water and heavy hydrocarbons from natural *** swirling separation of natural gas in the convergent-divergent nozzle was numerically simulated based on a new design which incorporates a central body. Axial distribution of the main parameters of gas flow was investigated,while the basic parameters of gas flow were obtained as functions of radius at the nozzle *** effect of the nozzle geometry on the swirling separation was *** numerical results show that water and heavy hydrocarbons can be condensed and separated from natural gas under the combined effect of the low temperature（-80℃） and the centrifugal field（482,400g,g is the acceleration of gravity）.The gas dynamic parameters are uniformly distributed correspondingly in the radial central region of the channel,for example the distribution range of the static temperature and the centrifugal acceleration are from -80 to -55℃and 220,000g to 500,000g,respectively,which would create good conditions for the cyclone separation of the ***,high gradients of gas dynamic parameters near the channel walls may impair the process of *** geometry of the nozzle has a great influence on the separation performance. Increasing the nozzle convergent angle can improve the separation *** swirling natural gas can be well separated when the divergent angle takes values from 4°to 12°in the convergent-divergent nozzle.

关键词： Swirling flow convergent-divergent nozzle supersonic natural gas separation numerical calculation

Neurological outcomes of patients admitted to the intensive care unit for cardiac arrest

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Chinese Medical Journal 2014年第16期127卷 3024-3026页

作者： Liu Lijun Zhu Jianliang yang Lin zhang yan Department of Emergency and Critical Care Medicine Second Affiliated Hospital of Soochow University Suzhou Jiangsu 215004China

Cardiac arrest （CA） is a major cause of death, with an estimated 300 000 cases of out-of-hospital CA reported in Europe and the United States each year. Advances in resuscitation techniques have improved survival such that approximately one-third of patients achieve return of spontaneous circulation （ROSC）. Nonetheless, only between half and one-third of patients who have achieved ROSC survive until discharge.

关键词： cardiac arrest neurological outcome risk factors multivariate analysis

Optimization of Uncertain Structures with Interval Parameters Considering Objective and Feasibility Robustness

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Chinese Journal of Mechanical Engineering 2018年第2期31卷 124-136页

作者： Jin Cheng Zhen-Yu Liu Jian-Rong Tan yang-yan zhang Ming-yang Tang Gui-Fang Duan State Key Laboratory of Fluid Power&Mechatronic Systems Zhejiang University State Key Laboratory of CAD&CG Zhejiang University Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education Harbin Institute of Technology

For the purpose of improving the mechanical performance indices of uncertain structures with interval parameters and ensure their robustness when fluctuating under interval parameters, a constrained interval robust optimization model is constructed with both the center and halfwidth of the most important mechanical performance index described as objective functions and the other requirements on the mechanical performance indices described as constraint functions. To locate the optimal solution of objective and feasibility robustness, a new concept of interval violation vector and its calculation formulae corresponding to different constraint functions are proposed. The math?ematical formulae for calculating the feasibility and objective robustness indices and the robustness?based preferential guidelines are proposed for directly ranking various design vectors, which is realized by an algorithm integrating Kriging and nested genetic algorithm. The validity of the proposed method and its superiority to present interval optimization approaches are demonstrated by a numerical example. The robust optimization of the upper beam in a high?speed press with interval material properties demonstrated the applicability and effectiveness of the proposed method in engineering.

关键词： Robust optimization Uncertain structure Interval violation vector Feasibility robustness Objective robustness Nested genetic algorithm

The oasis expansion and eco-environment change over the last 50 years in Manas River Valley, Xinjiang

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Science China Earth Sciences 2006年第2期49卷 163-175页

作者： CHENG Weiming ZHOU Chenghu LIU Haijiang zhang yang JIANG yan zhang Yichi YAO Yonghui State Key Laboratory of Resource and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Resource and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Resource and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Resource and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Resource and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Resource and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Resource and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

The oasis expansion and economic development of the Manas River Valley is one of the most successful examples in Xinjiang. In this paper, the oasis spatial distribution pattern and dynamic change were examined using imageries of Landsat MSS, TM and ETM, land use and topographic maps in six different periods (such as 1949, 1962, 1976, 1989, 1999 and 2001) over the last 50 years in the valley. The oasis expansion process could be divided into two stages according to the annual rate of oasis area increase, the fast oasization stage (from 1949 to 1976) when the oasis area ex-panded from 156.385 km2 in 1949 to 3,639.491 km2 in 1976 because of rapidly increased population and quickly enlarged farmland area; and the urbanization stage (from 1976 to 2001) when the ex-pansion ratio of farmland slowed down, and the urbanization process quickened, the total oasis area reached 5042.440 km2 in 2001. With the continuous expansion of oasis and farmland, a large quantity of river water was drawn into irrigation ditch and plain lakes, so only a small quantity of river water could flow into lakes, as a result, the Manas Lake dried up, salization and basification problems happened in the low-lying oasis region. The natural swamp around the lake was shrunk greatly and biodiversity decreased significantly. The driving force analysis reveals that human activities, such as reclamation and population growth, played a major role in the oasis expansion and ecological dete-rioration in the Manas River Valley. So further efforts should be made to improve the efficiency of water resource utility and adjust layout of the regional agricultural and animal husbandry to keep the sustainable development of oasis economic belt of the northern slope of Tianshan Mts.

关键词： Manas River Valley, oasization, urbanization, salinization and basification, remote sensing (RS).

Hydrochloric acid-enhanced radiofrequency ablation for treating a large hepatocellular carcinoma with spontaneous rapture:a case report

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Chinese Journal of Cancer 2017年第1期36卷 44-49页

作者： Ru-Hai Zou yang-Kui Gu Fei Gao Tian-Qi zhang Wang Yao Xiong-Ying Jiang yan-yang zhang Department of Minimally Invasive Interventional Therapy Sun Yat-sen University Cancer Center State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer Medicine Department of Oncologic Interventional Therapy The First Affiliated Hospital Sun Yat-sen University Department of Radiology Intervention Sun Yat-sen Memorial Hospital Sun Yat-sen University Department of Intervention The Third Affiliated Hospital Sun Yat-sen University

Background:A ruptured hepatocellular carcinoma(HCC)is often *** addition to surgery and transarterial embo?lization,radiofrequency ablation(RFA)might be another option for treating a ruptured ***,conven?tional RFA has a limited ablation zone;as such,it is rarely used to treat ruptured *** presentation:This case was a 60?year?old man who had a large,ruptured HCC in which hydrochloric acid(HCl)?enhanced RFA successfully controlled the bleeding and made the tumor completely ***:Considering the effectiveness of HCl?enhanced RFA in achieving hemostasis and tumor ablation,it might be a new option for treating large,ruptured HCCs.

关键词： Hydrochloric acid Radiofrequency ablation Spontaneous rupture Hepatocellular carcinoma

A novel graph oversampling framework for node classification in class-imbalanced graphs

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Science China(Information Sciences) 2024年第6期67卷 214-229页

作者： Riting XIA Chunxu zhang yan zhang Xueyan LIU Bo yang Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University College of Artificial Intelligence Jilin University College of Computer Science and Technology Jilin University College of Communication Engineering Jilin University

Graph neural network(GNN) is a promising method to analyze graphs. Most existing GNNs adopt the class-balanced assumption, which cannot deal with class-imbalanced graphs well. The oversampling technique is effective in alleviating class-imbalanced problems. However, most graph oversampling methods generate synthetic minority nodes and their edges after applying GNNs. They ignore the problem that the representations of the original and synthetic minority nodes are dominated by majority nodes caused by aggregating neighbor information through GNN before oversampling. In this paper, we propose a novel graph oversampling framework, termed distribution alignment-based oversampling for node classification in classimbalanced graphs(named Graph-DAO). Our framework generates synthetic minority nodes before GNN to avoid the dominance of majority nodes caused by message passing in GNNs. Additionally, we introduce a distribution alignment method based on the sum-product network to learn more information about minority nodes. To our best knowledge, it is the first to use the sum-product network to solve the class-imbalanced problem in node classification. A large number of experiments on four real datasets show that our method achieves the optimal results on the node classification task for class-imbalanced graphs.

关键词： graph neural network class-imbalanced graphs sum-product network oversampling node classification

Climatic implications in earlywood and latewood width indices of Chinese pine in north central China

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Journal of Forestry Research 2024年第3期35卷 143-153页

作者： Kaixuan yang Junzhou zhang Haowen Fan Yuan yan College of Geographic Sciences Qinghai Normal UniversityXining 810016People's Republic of China Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation(Ministry of Education) Xining 810016People's Republic of China Key Laboratory of Western China's Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730030People's Republic of China Gansu Liancheng Forest Ecosystem Field Observation and Research Station Lanzhou UniversityLanzhou 730333People's Republic of China School of Geography and Information Engineering University of GeoscienceWuhan 430074People's Republic of China

Latewood width(LWW)indices of trees are considered a reliable proxy of summer precipitation in the Northern ***,the strong coupling and high correlation between earlywood width(EWW)and LWW indices often prevent registration of climate signals of the LWW *** this study,328-year-long earlywood width and latewood width chronologies were developed from Chinese pine at two sites in the Hasi Mountains,north central *** climate responses of these chronologies were analyzed and the LWW index used to derive sum-mer precipitation *** analyses showed that LWW was particularly influenced by earlywood growth and recorded stronger climate signals of the previous year as EWW,rather than those of the current year with infrequent summer climate ***,after removing the effect of earlywood growth using a simple regression model,the adjusted LWW chronology(LWW_(adj))showed a strong relationship with July precipitation in dry *** suggests that the LWW_(adj) chronology has the potential to be used to investigate long-term variability in summer precipitation in drought-limited regions.

关键词： Dendroclimatology Latewood width Climate response Summer precipitation Earlywood effect

Recent progresses in thermal treatment of β-Ga_(2)O_(3) single crystals and devices

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1659-1677页

作者： Yuchao yan Zhu Jin Hui zhang Deren yang State Key Laboratory of Silicon and Advanced Semiconductor Materials and School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices ZJU-Hangzhou Global Scientific and Technological Innovation CenterHangzhou 311200China

In recent years,ultra-wide bandgap β-Ga_(2)O_(3) has emerged as a fascinating semiconductor material due to its great potential in power and photoelectric *** semiconductor industrial,thermal treatment has been widely utilized as a convenient and effective approach for substrate property modulation and device ***,a thorough summary of β-Ga_(2)O_(3) substrates and devices behaviors after high-temperature treatment should be *** this review,we present the recent advances in modulating properties of β-Ga_(2)O_(3) substrates by thermal treatment,which include three major applications:(ⅰ)tuning surface electrical properties,(ⅱ)modifying surface morphology,and(ⅲ)oxidating ***,regulating electrical contacts and handling with radiation damage and ion implantation have also been discussed in device *** each category,universal annealing conditions were speculated to figure out the corresponding problems,and some unsolved questions were proposed *** review could construct a systematic thermal treatment strategy for various purposes and applications of β-Ga_(2)O_(3).

关键词： β-gallium oxide thermal treatment substrates devices

High-precision parallel computing model of solute transport based on GPU acceleration

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Journal of Hydrodynamics 2024年第1期36卷 202-212页

作者： Shang-hong zhang Rong-qi zhang Wen-da Li Xi-yan yang yang Zhou School of Water Resources and Hydropower Engineering North China Electric Power UniversityBeijing102206China Hubei Key Laboratory of Intelligent yangtze and Hydroelectric Science China Yangtze Power Co.Ltd.Yichang443133China

The scenario simulation analysis of water environmental emergencies is very important for risk prevention and control,and emergency *** quickly and accurately simulate the transport and diffusion process of high-intensity pollutants during sudden environmental water pollution events,in this study,a high-precision pollution transport and diffusion model for unstructured grids based on Compute Unified Device Architecture(CUDA)is *** finite volume method of a total variation diminishing limiter with the Kong proposed r-factor is used to reduce numerical diffusion and oscillation errors in the simulation of pollutants under sharp concentration conditions,and graphics processing unit acceleration technology is used to improve computational *** advection diffusion process of the model is verified numerically using two benchmark cases,and the efficiency of the model is evaluated using an engineering *** results demonstrate that the model perform well in the simulation of material transport in the presence of sharp ***,it has high computational *** acceleration ratio is 46 times the single-thread acceleration effect of the original *** efficiency of the accelerated model meet the requirements of an engineering application,and the rapid early warning and assessment of water pollution accidents is achieved.

关键词： Pollution transport and diffusion model parallel computing Compute Unified Device Architecture(CUDA) pollution event