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| 1 | 完全匹配层吸收边界条件研究显示文摘为了提高人为截断边界的吸收效率,提出了一种完全匹配层边界吸收衰减因子——正、余弦型吸收衰减因子。采用声波波动方程,并应用统一格式的高阶交错网格有限差分法来构建正演递推算子实现声波全波场正演计算(边界处差分阶数依次递减)。以单层均匀介质模型为例,研究不同吸收层厚度与介质速度和声波模拟主频的关系。数值试算结果表明,不同吸收层厚度所消耗的时间按一定的函数关系变化,边界吸收层厚度与速度和最大频率之间无明确的对应关系,边界吸收层厚度所占节点数不小于6个时就可以得到较好的边界吸收效果。以Marmousi模型为例研究了完全匹配层边界吸收衰减因子在复杂地质模型中的边界吸收效果,与解析解的对比可知,该边界吸收衰减因子能在复杂地质模型中取得满意的边界吸收效果。 | 陈可洋 | 2010 | 石油物探2010，49，5： | 63 |
| 2 | Treatment of Helicobacter pylori infection in atrophic gastritis显示文摘Helicobacter pylori(Hp) is a major human pathogen causing chronic, progressive gastric mucosal damage and is linked to gastric atrophy and cancer. Hp-positive individuals constitute the major reservoir for transmission of infection. There is no ideal treatment for Hp. Hp infection is not cured by a single antibiotic, and sometimes, a combined treatment with three or more antibiotics is ineffective. Atrophic gastritis(AG) is a chronic disease whose main features are atrophy and/or intestinal metaplasia of the gastric glands, which arise from long-standing Hp infection. AG is reportedly linked to an increased risk for gastric cancer, particularly when extensive intestinal metaplasia is present. Active or past Hp infection may be detected by conventional methods in about two-thirds of AG patients. By immunoblotting of sera against Hp whole-cell protein lysates, a previous exposure to Hp infection is detected in all AG patients. According to guidelines, AG patients with Hp positivity should receive eradication treatment. The goals of treatment are as follows:(1) Cure of infection, resolution of inflammation and normalization of gastric functions;(2) possible reversal of atrophic and metaplastic changes of the gastric mucosa; and(3) prevention of gastric cancer. An ideal antibiotic regimen for Hp should achieve eradication rates of approximately 90%, and complex multidrug regimens are required to reach this goal. Amongst the factors associated with treatment failure are high bacterial load, high gastric acidity, Hp strain, smoking, low compliance, overweight, and increasing antibiotic resistance. AG, when involving the corporal mucosa, is linked to reduced gastric acid secretion. At a non-acidic intra-gastric p H, the efficacy of the common treatment regimens combining proton pump inhibitors with one or more antibiotics may not be the same as that observed in patients with Hp gastritis in an acid-producing stomach. Although the efficacy of these therapeutic regimens has been thoroughly tested in subjects with Hp infection, there is a paucity of evidence in the subgroupof patients with AG. Bismuth-based therapy may be an attractive treatment in the specific setting of AG, and specific studies on the efficacy of bismuth-based therapies are needed in patients with AG. | Edith Lahner Marilia Carabotti Bruno Annibale | 2018 | World Journal of Gastroenterology2018，24，22： | 57 |
| 3 | STUDY ON CONDITIONS AND MECHANISMS OF DEBRIS FLOW INITIATION BY MEANS OF EXPERIMENT显示文摘As a debris flow starts in the upper reaches of a gully or a ravine, its scale and destructive power are not very large. It rapidly strengthens in its flow process by eroding and carrying loose solid material along its running route, and at last, it accumulates great destructive power. If the initiation conditions may be regulated and controlled to prevent debris flows, practical benefits will be obtained. To study the conditions and | 崔鹏 | 1992 | Chinese Science Bulletin1992，37，9： | 41 |
| 4 | 基于条件随机场方法的开放领域新词发现显示文摘开放领域新词发现研究对于中文自然语言处理的性能提升有着重要的意义.利用条件随机场(condition random field,简称CRF)可对序列输入标注的特点,将新词发现问题转化为预测已分词词语边界是否为新词边界的问题.在对海量规模中文互联网语料进行分析挖掘的基础上,提出了一系列区分新词边界的统计特征,并采用CRF方法综合这些特征实现了开放领域新词发现的算法,同时比较了K-Means聚类、等频率、基于信息增益这3种离散化方法对新词发现结果的影响.通过在SogouT大规模中文语料库上的新词发现实验,验证了所提出的方法有较好的效果. | 陈飞 刘奕群 魏超 张云亮 张敏 马少平 | 2013 | 软件学报2013，24，5： | 42 |
| 5 | Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016显示文摘With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O3,decreased. Spatially, the PM2.5, PM10, SO2, and CO concentrations were higher in the northern YRD region, and NO2 and O3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM2.5 was the largest contributor to air pollution in the YRD region, followed by O3, PM10, and NO2.However, particulate matter pollution has declined gradually, while O3 pollution worsened.Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM2.5 concentration was inversely related to wind speed, while O3 concentration was positively correlated with temperature and negatively correlated with relative humidity.The air quality improvement in recent years was mainly attributed to emission reductions.During 2014–2016, PM2.5, PM10, SO2, NOx, CO, NH3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region. | Tao Ma Fengkui Duan Kebin He Yu Qin Dan Tong Guannan Geng Xuyan Liu Hui Li Shuo Yang Siqi Ye Beiyao Xu Qiang Zhang Yongliang Ma | 2019 | Journal of Environmental Sciences2019，31，9： | 26 |
| 6 | Continuity of Higher Order Commutators on Certain Hardy Spaces | DING Yong LU Shan Zhen Department of Mathematics,Beijing Normal University,Beijing 100875.P.R.China E-mail:dingy@bnu.edu.cn lusz@bnu.edu.cnZHANG Pu Department of Mathematics.Zhejiang University(at Xixi Campus).Hangzhou 310028,P.R.China,E-mail:zhpjj@263,net | 2002 | Acta Mathematica Sinica,English Series2002，18，2： | 21 |
| 7 | A preliminary study on ras protein expression in human esophageal cancer and precancerous lesions显示文摘INTRODUCTIONThe esophageal carcinoma is a common malignanttumor in Linzhou City (Linxian) of Henan Provincein northern China.Although the etiology andnatural history of csophageal carcinoma are notclear,a substantial amount of evidence has beenprovided to suggest that the development of humanesophageal squamous cell carcinomas (SCC) is amultistage progressive process.An | Jian Li Chang Wei Feng Zhi Guo Zhao Qi Zhou Li Dong Wang | 2000 | World Journal of Gastroenterology2000，6，2： | 15 |
| 8 | A data-driven health indicator extraction method for aircraft air conditioning system health monitoring显示文摘Prognostics and Health Management(PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model,one of the challenges for airborne system health monitoring is to find an appropriate health indicator that is highly related to the actual degradation state of the system. This paper proposed a novel health indicator extraction method based on the available sensor parameters for the health monitoring of Air Conditioning System(ACS) of a legacy commercial aircraft model. Firstly, a specific Airplane Condition Monitoring System(ACMS) report for ACS health monitoring is defined. Then a non-parametric modeling technique is adopted to calculate the health indicator based on the raw ACMS report data. The proposed method is validated on a single-aisle commercial aircraft widely used for short and medium-haul routes, using more than 6000 ACMS reports collected from a fleet of aircraft during one year. The case study result shows that the proposed health indicator can effectively characterize the degradation state of the ACS, which can provide valuable information for proactive maintenance plan in advance. | Jianzhong SUN Chaoyi LI Cui LIU Ziwei GONG Ronghui WANG | 2019 | Chinese Journal of Aeronautics2019，32，2： | 14 |
| 9 | A SIMPLE WAY CONSTRUCTING SYMPLECTICRUNGE-KUTTA METHODS显示文摘With the help of symplecticity conditions of Partitioned Runge-Kutta methods,a simple way constructing symplectic methods is derived. Examples including several classes of high order symplectic Runge-Kutta methods are given, and showedup the relationship between existing high order Runge-Kutta methods. | Geng Sun(Institute of Mathematics, Academia Sinica, Beijing 100080, China) | 2000 | Journal of Computational Mathematics2000，18，1： | 13 |
| 10 | Approximate Degree Reduction of Bezier Curves显示文摘ApproximateDegreeReductionofBezierCurves*HuShimin(胡事民),SunJiaguang(孙家广),JinTongguang(金通光)+,WangGuozhao(汪国昭)+DepartmentofCompu... | 胡事民 孙家广 金通光 汪国昭 | 1998 | Tsinghua Science and Technology1998，3，2： | 10 |
| 11 | Aging Precipitation Behavior of 18Cr-16Mn-2Mo-1.1N High Nitrogen Austenitic Stainless Steel and Its Influences on Mechanical Properties显示文摘The solution-treated (ST) condition and aging precipitation behavior of 18Cr-16Mn-2Mo-1.1N high nitrogen austenitic stainless steel (HNS) were investigated by optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM). The results show that the ST condition of 18Cr-16Mn-2Mo-1.1N HNS with wN above 1% is identified as 1 100 ℃ for 90 min, followed by water quenching to make sure the secondary phases completely dissolve into austenitic matrix and prevent the grains coarsening too much. Initial time-temperature-precipitation (TTP) curve of aged 18Cr-16Mn-2Mo-1.1N HNS which starts with precipitation of 0.05% in volume fraction is defined and the 'nose' temperature of precipitation is found to be 850 ℃ with an incubation period of 1 min. Hexagonal intergranular and cellular Cr2N with a=0.478 nm and c=0.444 nm precipitates gradually increase in the isothermal aging treatment. The matrix nitrogen depletion due to the intergranular and a few cellular Cr2N precipitates induces the decay of Vickers hardness, and the increment of cellular Cr2N causes the increase in the values. Impact toughness presents a monotonic decrease and SEM morphologies show the leading brittle intergranular fracture. The ultimate tensile strength (UTS), yield strength (YS) and elongation (El) deteriorate obviously. Stress concentration occurs when the matrix dislocations pile up at the interfaces of precipitation and matrix, and the interfacial dislocations may become precursors to the misfit dislocations, which can form small cleavage facets and accelerate the formation of cracks. | LI Hua-bing, JIANG Zhou-hua, FENG Hao, MA Qi-feng, ZHAN Dong-ping (School of Materials and Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China) | 2012 | Journal of Iron and Steel Research(International)2012，19，8： | 10 |
| 12 | Study on correlations of modal frequencies and environmental factors for a suspension bridge based on improved neural networks显示文摘By using of long-term monitoring data of Runyang Suspension Bridge,the improved back-propagation neural networks (BPNNs) are formulated for modeling the correlations between modal frequencies and environmental conditions including wind,temperature and vehicle load.Then,with the correlation models the environmental effects on modal frequencies are quantified and the abnormal changes of measured frequencies are detected by means of the hypothesis tests.Analysis results reveal that BPNN-based correlation models improved by both early stopping and Bayesian regularization techniques exhibit excellent generalization capability.And the developed correlation models can effectively reduce the environmental variability in modal frequencies.The t-test method provides a good capability to detect the damage-induced 0.16% and 0.12% abnormal changes of the 5th and 6th modal frequencies,respectively.Hence,the proposed method is suitable for real-time monitoring of suspension bridge conditions. | DING YouLiang,DENG Yang & LI AiQun Key Laboratory of Concrete and Prestressed Concrete Structure of Ministry of Education,Southeast University,Nanjing 210096,China | 2010 | Science China(Technological Sciences)2010，53，9： | 9 |
| 13 | Fault diagnosis based on measurement reconstruction of HPT exit pressure for turbofan engine显示文摘Aero-engine gas path health monitoring plays a critical role in Engine Health Management(EHM). To achieve unbiased estimation, traditional filtering methods have strict requirements on measurement parameters which sometimes cannot be measured in engineering. The most typical one is the High-Pressure Turbine(HPT) exit pressure, which is vital to distinguishing failure modes between different turbines. For the case of an abrupt failure occurring in a single turbine component, a model-based sensor measurement reconstruction method is proposed in this paper. First,to estimate the missing measurements, the forward algorithm and the backward algorithm are developed based on corresponding component models according to the failure hypotheses. Then,a new fault diagnosis logic is designed and the traditional nonlinear filter is improved by adding the measurement estimation module and the health parameter correction module, which uses the reconstructed measurement to complete the health parameters estimation. Simulation results show that the proposed method can well restore the desired measurement and the estimated measurement can be used in the turbofan engine gas path diagnosis. Compared with the diagnosis under the condition of missing sensors, this method can distinguish between different failure modes, quantify the variations of health parameters, and achieve good performance at multiple operating points in the flight envelope. | Xin ZHOU Feng LU Jinquan HUANG | 2019 | Chinese Journal of Aeronautics2019，32，5： | 9 |
| 14 | Comprehensive Mathematical Model for Coal Combustion in a Circulating Fluidized Bed Combustor显示文摘Char combustion is on a special reducing condition in the dense bed of a circulating fluidized bed combustor. Experimental findings were used to develop a comprehensive mathematical model to simulate the hydrodynamic and combustion processes in a circulating fluidized bed combustor. In the model, gas solid interaction was used to account for the mass transfer between the bubble phase and the emulsion phase in the dense bed, which contributes to the reducing atmosphere in the dense bed. A core annular structure was assumed in the dilute area rather than a one dimensional model. The submodels were combined to build the comprehensive model to analyze the combustion in a circulating fluidized bed combustor and the effect of operating parameters on the coal combustion. The model predictions agree well with experimental results. | 金晓钟 吕俊复 杨海瑞 刘青 岳光溪 冯俊凯 | 2001 | Tsinghua Science and Technology2001，6，4： | 9 |
| 15 | Spatiotemporal Variations and Regional Transport of Air Pollutants in Two Urban Agglomerations in Northeast China Plain显示文摘Characteristics of air pollution in Northeast China(NEC) received less research attention in the past comparing to other heavily polluted regions in China.Spatiotemporal variations of six criteria air pollutants(PM10, PM2.5, SO2, NO2, O3 and CO) in Central Liaoning Urban Agglomeration(CLUA) and Harbin-Changchun Urban Agglomeration(HCUA) in NEC Plain were analyzed in this study based on three-year hourly observations of air pollutants and meteorological variables from 2015 to 2017.The results indicated that the annual mean concentrations of air pollutants are generally higher in the middle and southern regions in NEC Plain and lower in the northern region.Megacities such as Shenyang, Harbin and Changchun experience severe air pollution, with a three-year averaged air quality index(AQI) larger than 80, far exceeding the daily AQI standard at the first-level of 50 in China.The annual mean PM and SO2 concentrations decrease most significantly in NEC urban agglomerations from 2015 to 2017, followed by CO and NO2, while O3 shows a slight increasing trend.All the six pollutants exhibit obvious seasonal and diurnal variations, and these variations are dictated by local emission and meteorological conditions.PM2.5 and O3 concentrations in NEC urban agglomerations strongly depend on wind conditions.High O3 concentrations at different cities usually occur in presence of strong winds but are independent on wind direction(WD), while high PM2.5 is usually accompanied by weak winds and poor dispersion condition, and sometimes also occur when the northerly or southerly winds are strong.Regional transport of air pollutants between NEC urban agglomerations is common.A severe haze event on November 1–4, 2017 is examined to demonstrate the role of regional transport on pollution. | LI Xiaolan HU Xiaoming SHI Shuaiyi SHEN Lidu LUAN Lan MA Yanjun | 2019 | Chinese Geographical Science2019，29，6： | 9 |
| 16 | Cracking conditions of crude oil under different geological environments显示文摘There are mainly 3 kinds of existing states of oil generating from source rocks,that is,dispersive liquid hydrocarbon inside of source rock,dispersive liquid hydrocarbon outside of source rock and concentrated liquid hydrocarbon outside of source rock.Because of the differences in thermal history and medium conditions around,and the interaction of organic and inorganic matter,the liquid hydrocarbon with 3 kinds of existing state has different cracking conditions.The gas generation dynamics experiments of crude oil matching different mediums indicate that the distribution of activation energy of methane changes a lot according to medium difference.The carbonate has a main influence on oil cracking conditions and can largely reduce its activation energy,which reflects the lower cracking temperature of crude oil.The mudstone takes a second place and the sandstone is the smallest.The catalytic cracking function to the oil of the carbonate,of the mudstone and of the sandstone changes weaken in turn.The corresponding Ro values of main gas generation period in different mediums are as follows:1.5%―3.8%with pure crude oil,1.2%―3.2%with dispersive crude oil in carbonate,1.3%~3.4% with dispersive crude oil in mudstone and 1.4%―3.6%with dispersive crude oil in sandstone.The influence of pressure to crude oil cracking is relatively complicated.In the low heating speed condition, pressure restrains the oil cracking and gas generation,but in the high heating speed condition,pressure has an indistinctive influence to the oil cracking and gas generation.Pressure also makes a different effort in different evolvement stage.Taking the middle and lower Cambrian source rocks in the Tarim Basin as an example,primary oil generating quantity is 2232.24×10 8 t,residual oil and oil cracking gas quantity is 806.21×10 8 t and 106.95×10 12 m 3 respectively. | ZHAO WenZhi,WANG ZhaoYun,ZHANG ShuiChang&WANG HongJun Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China | 2008 | Science China Earth Sciences2008，51，S1： | 8 |
| 17 | STUDIES ON CULTURE CONDITIONS OF BENTHIC DIATOMS FOR FEEDING ABALONE Ⅱ. EFFECTS OF SALINITY pH, NITROGENOUS AND PHOSPHATE NUTRIENTS ON GROWTH RATE显示文摘Effects of salinity , pH, nitrogenous and phosphate nutrients on the growth rate of four species of benthic diatoms were studied by using the method of in situ optical density measurement . The optimal culture conditions for the four species of diatoms are as follows: for Amphora coffeaeformis , s 35 ; pH 8.5; N03 -N 1.54, NH4-N, 7.0; CO (NH2)2-N, 2.5 (mg/L); PO43--P 1.13 (mg/L) ; for Cocconeis scutellum var parva , s 30 ; pH 8.5 ; NO3-N 3.08, NH4+-N 3.5, CO(NH2)2-N 5.0 (mg/L); pO43--P0.283 (mg/L), for Navicula corymbosa s 25; pH 8.0; N03- -N 1.54, NH4+ -N 3.5, CO(NH2)2-N 5.0(mg/L); PO43--P0.565 (mg/L), for Navicula mollis , s 25 ; pH 8.0; NO3- - 1.54 NH4+ - N 1.75, CO(NH2)2 -N 1.25 (mg/L), P043--P 0.141(mg/L). | 王起华 李梅 王淑红 丁明进 李雅娟 程爱华 | 1998 | Chinese Journal of Oceanology and Limnology1998，16，1： | 7 |
| 18 | On Hrmander condition显示文摘LET T:D→D′be a continuous linear operatorl, and K denote the distribution kernel of T. Assume that restriction of K to the set{( x, y ) ∈R^n x R^n, x≠y}satisfies the following 'size' and 'smoothness' conditions: | YANG Qixiang, YAN Lixin and DENG DonggaoDepartment of Mathematics, Zhongshan University, Guangzhou 510275, China | 1997 | Chinese Science Bulletin1997，42，16： | 7 |
| 19 | A New Method for Modelling and Simulation of the Dynamic Behaviour of the Wheel-rail contact显示文摘This paper presents a new method for modelling and simulation of the dynamic behaviour of the wheel-rail contact. The proposed dynamic wheel-rail contact model comprises wheel-rail contact geometry, normal contact problem, tangential contact problem and wheelset dynamic behaviour on the track. This two-degree of freedom model takes into account the lateral displacement of the wheelset and the yaw angle. Single wheel tread rail contact is considered for all simulations and Kalker s linear theory and heuristic non-linear creep models are employed. The second order differential equations are reduced to first order and the forward velocity of the wheelset is increased until the wheelset critical velocity is reached. This approach does not require solving mathematical equations in order to estimate the critical velocity of the dynamic wheel-rail contact model. The mathematical model is implemented in Matlab using numerical differentiation method. The simulated results compare well with the estimated results based on classical theory related to the dynamic behaviour of rail-wheel contact so the model is validated. | Arthur Anyakwo Crinela Pislaru Andrew Ball | 2012 | International Journal of Automation and computing2012，9，3： | 7 |
| 20 | Semi-solid rheocasting of grain refined aluminum alloy 7075显示文摘Near-net shape rheocasting with the Council for Scientific and Industrial Research Rheo casting system(CSIR-RCS) and a high pressure die casting machine was successfully performed on Al-5Ti-1B grain refined aluminum alloy 7075.Grain refinement levels used were 0.03% Ti,0.13% Ti and 0.29% Ti(mass fraction).Tensile tests reveal that the ultimate tensile strengths,at all levels of grain refinement,are at least 97% of the specified minimum.Elongation at fracture increases with the increase of level of grain refinement although a maximum elongation is only 76% of the required minimum elongation in the case of 0.29% Ti.Incipient melting,during solution treatment,of the low melting point multinary eutectic causes porosity in the material and accounts for poor elongation results.0.03% Ti has a coarse eutectic structure forming larger pores while 0.29% Ti has a fine structure forming fine pores in the multinary eutectic.The 0.2% offset yield strengths of all the grain refinement levels are at least equal to or above the specified minimum and a decrease is observed with the increase of grain refinement level.There is a clear reduction in grain size from 0.03% Ti to 0.29% Ti in the as-cast condition.An underlying grain structure develops in the T6 condition material which has an inverse size to the as-cast structure;coarse grained as-cast material results in fine grained T6 condition material after solution heat treatment.The decrease in the offset yield strength as grain refinement increases correlates very strongly with the T6 grain sizes according to a Hall-Petch type relationship. | U.A.CURLE G.GOVENDER | 2010 | 中国有色金属学会会刊:英文版2010，20，S3： | 7 |
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