检索结果-南通市图书馆

Support Vector Machine combined with K-Nearest Neighbors for Solar Flare Forecasting

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 441-447页

作者： Rong Li Hua-Ning Wang Han He yan-mei cui Zhan-Le Du National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

A method combining the support vector machine （SVM） the K-Nearest Neighbors （KNN）, labelled the SVM-KNN method, is used to construct a solar flare forecasting model. Based on a proven relationship between SVM and KNN, the SVM-KNN method improves the SVM algorithm of classification by taking advantage of the KNN algorithm according to the distribution of test samples in a feature space. In our flare forecast study, sunspots and 10cm radio flux data observed during Solar Cycle 23 are taken as predictors, and whether an M class flare will occur for each active region within two days will be predicted. The SVM- KNN method is compared with the SVM and Neural networks-based method. The test results indicate that the rate of correct predictions from the SVM-KNN method is higher than that from the other two methods. This method shows promise as a practicable future forecasting model.

关键词： Sun flare - Sun sunspot - Sun activity - Sun magnetic fields

Predicting the CME arrival time based on the recommendation algorithm

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第8期21卷 59-74页

作者： Yu-Rong Shi yan-Hong Chen Si-Qing Liu Zhu Liu Jing-Jing Wang yan-mei cui Bingxian Luo Tian-Jiao Yuan Feng Zheng Zisiyu Wang Xin-Ran He Ming Li National Space Science Center Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Science and Technology on Environmental Space Situation Awareness Chinese Academy of SciencesBeijing 100190China Department of Computer Science and Engineering Southern University of Science and TechnologyShenzhen 518055China

CME is one of the important events in the sun-earth system as it can induce geomagnetic disturbance and an associated space environment *** is of special significance to predict whether CME will reach the Earth and when it will *** this paper,we firstly built a new multiple association list for 215 different events with 18 characteristics including CME features,eruption region coordinates and solar wind *** on the CME list,we designed a novel model based on the principle of the recommendation algorithm to predict the arrival time of *** to the two commonly used calculation methods in the recommendation system,cosine distance and Euclidean distance,a controlled trial was carried out *** feature has been found to have its own appropriate *** error analysis indicates the result using the Euclidean distance similarity is much better than that using cosine distance *** mean absolute error and root mean square error of test data in the Euclidean distance are 11.78 and 13.77 h,close to the average level of other CME models issued in the CME scoreboard,which verifies the effectiveness of the recommendation *** work gives a new endeavor using the recommendation algorithm,and is expected to induce other applications in space weather prediction.

关键词： Sun:coronal mass ejections(CMEs) method:recommendation algorithm

A Novel Model for Describing Rail Weld Irregularities and Predicting Wheel-Rail Forces Using a Machine Learning Approach

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2025年第1期142卷 555-577页

作者： Linlin Sun Zihui Wang Shukun cui Ziquan yan Weiping Hu Qingchun Meng State Key Laboratory of High-Speed Railway Track System China Academy of Railway Sciences Corporation LimitedBeijing100081China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing100081China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed *** can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and *** researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry ***,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric *** this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to *** vertical dynamic forces in the time and frequency domains were compared under different running *** forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed ***,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is *** results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the *** ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.

关键词： Rail weld irregularity high-speed railway vehicle-track coupled dynamics wheel/rail dynamic vertical force artificial neural networks

Synergistic promotion strategy of “dual-site” and “dual-path” to enhance the C–C coupling between CO2 and HCHO driven by photoelectrocatalysis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2025年第1期100卷 39-49页

作者： Hongqiang yang Jianfeng Zheng Guoyu Wang Yifei Gao Yatao yang Jia Li Xiaojin Han yan cui Zhanggen Huang National Key Laboratory of High Efficiency and Low Carbon Utilization of Coal Institute of Coal Chemistry Chinese Academy of Science University of Chinese Academy of Science Shenyang University of Chemical Technology

Photoelectrocatalytic coupling CO2and volatile organic compounds （VOCs） is a promising green strategy for the synergistic conversion of the two carbon-containing resources to *** catalytic efficiency is always at the mercy of chemical inertness of CO2and the competitive hydrogen evolution of ***,a modified g-C3N4/ZnAl-LDH Z-scheme heterojunction catalyst with dual reaction site was rationally designed and precisely *** Faraday efficiency of ethanol reached 68.67%with a corresponding formation rate of 227.3μmol *** revealed by in-situ characterizations and density functional theory calculations,CO2and HCHO were absorbed at Zn site and N site,***,*CO generated from CO2and HCHO was converted to*CH3O and*CHO on the dual-active-site *** detailed reaction mechanism experiments indicated that C–C coupling only occurred between*CO and*CH3O in electrocatalysis *** from the“*CO+*CH3O”path,another“*CO+*CHO”coupling path was also detected in photoelectrocatalytic *** selectivity of ethanol was significantly enhanced due to the synthesis of dual-site catalyst and the dual-path coupling path between CO2and HCHO simultaneously driven by light and electricity.

关键词： Photoelectrocatalysis Z-scheme C–C coupling Ethanol

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第1期20卷 159-173页

作者： Man Han Deyang Zeng Wei Tan Xingxing Chen Shuyuan Bai Qiong Wu Yushan Chen Zhen Wei Yufei mei yan Zeng Brain Science and Advanced Technology Institute Wuhan University of Science and TechnologyWuhanHubei ProvinceChina Geriatric Hospital Affiliated to Wuhan University of Science and Technology WuhanHubei ProvinceChina School of Public Health Wuhan University of Science and TechnologyWuhanHubei ProvinceChina

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral *** studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region–specific,particularly involving the corticolimbic system,including the ventral tegmental area,nucleus accumbens,prefrontal cortex,amygdala,and *** how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress *** this review,we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of *** focused on associated molecular pathways and neural circuits,with special attention to the brain-derived neurotrophic factor–tropomyosin receptor kinase B signaling pathway and the ventral tegmental area–nucleus accumbens dopamine *** determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature,severity,and duration of stress,especially in the above-mentioned brain regions of the corticolimbic ***,BDNF might be a biological indicator regulating stress-related processes in various brain regions.

关键词： amygdala chronic mild stress chronic social defeat stress corticolimbic system depression hippocampus medial prefrontal cortex nucleus accumbens social stress models ventral tegmental area

在线全文

学校读者我要写书评

暂无评论

小麦纹枯病化学和生物防治研究进展

农药 2020年第9期59卷 630-635,679页

作者：肖茜闫翠梅齐永志甄文超河北农业大学植物保护学院河北保定071001 河北农业大学农学院河北保定071001 河北农业大学省部共建华北作物改良与调控国家重点实验室河北保定071001 河北省作物生长调控重点实验室河北保定071001

由禾谷丝核菌引起的小麦纹枯病严重降低了小麦的产量和品质。通过对近20年国内外有关化学和生物防治小麦纹枯病的研究报道进行分析发现,防治小麦纹枯病化学药剂主要包括三唑类、酰胺类、抗生素类等,三唑类药剂防效最高;禾谷丝核菌对三... 详细信息

由禾谷丝核菌引起的小麦纹枯病严重降低了小麦的产量和品质。通过对近20年国内外有关化学和生物防治小麦纹枯病的研究报道进行分析发现,防治小麦纹枯病化学药剂主要包括三唑类、酰胺类、抗生素类等,三唑类药剂防效最高;禾谷丝核菌对三唑类和酰胺类药剂的抗性风险为中到低等,而对抗生素类可能存在较高抗性风险。生防制剂主要包括芽孢杆菌、木霉菌和放线菌等,芽孢杆菌类生防菌剂应用较广、防效较优。未来应加强禾谷丝核菌抗性监测、与药剂互作分子机制和稳定生防制剂田间防效方面的研究。

关键词：小麦纹枯病禾谷丝核菌杀菌剂抗性风险敏感性

全切缘显示ESD标本病理检查方法的优点及推广

在线全文

学校读者我要写书评

暂无评论

世界华人消化杂志 2017年第26期25卷 2401-2406页

作者：崔艳梅刘伟吴在增郑智勇刘建强解放军福州总医院病理科福建省福州市350025 福建中医药大学附属人民医院病理科福建省福州市350025 解放军福州总医院消化内科福建省福州市350025

目的对"消化道内镜黏膜下层剥离术(endoscopic submucosal dissection,ESD)标本取材规范"进行改进,并提出精确显示高级别上皮内瘤变(high grade intraepithelial neoplasia,HGEIN)早期浸润的方法.方法建立一种"全切缘显示"的ESD标本取材... 详细信息

目的对"消化道内镜黏膜下层剥离术(endoscopic submucosal dissection,ESD)标本取材规范"进行改进,并提出精确显示高级别上皮内瘤变(high grade intraepithelial neoplasia,HGEIN)早期浸润的方法.方法建立一种"全切缘显示"的ESD标本取材法,应用于120例消化道ESD标本.用0.05%24型蛋白酶消化40 min修复的Ⅳ型胶原免疫组化染色,观察HGEIN基底膜是否完整,判断有无早期浸润.对患者性别、年龄、病变的部位、肉眼分型、组织学类型、切缘侵犯情况等进行统计分析,以判断该取材法的临床实用性.结果食管30例、胃64例、肠26例;男性70例,女性50例,年龄23-81岁,平均58岁.肉眼分型:Ⅰ型42例,ⅡA型43例,ⅡB型29例,ⅡC型6例.组织学类型:HGEIN39例;癌变17例,其中3例为M1,5例为M2,6例为M3,3例为***有2例口端切缘侵犯.8例疑癌变标本,通过Ⅳ型胶原标记后6例证实为HGEIN,2例为癌变.结论 "全切缘显示"ESD标本病理检查方法,不仅上下切缘及两侧切缘都可以完整显示,且不增加工作量,无需大包埋盒和平推式滑动切片机等专用设备.对于HGEIN疑癌病例用Ⅳ型胶原免疫组化染色显示早期癌浸润效果佳.

关键词：内镜黏膜下剥离术取材制片病理诊断

Skew-gradient representations of constrained mechanical systems

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2015年第7期36卷 873-882页

作者： Fengxiang mei Jinchao cui School of Aerospace Engineering Beijing Institute of Technology School of Science Jiangnan University

The characteristics of stationary and non-stationary skew-gradient systems are studied. The skew-gradient representations of holonomic systems, Birkhoffian systems, generalized Birkhoffian systems, and generalized Hamiltonian systems are given. The characteristics of skew-gradient systems are used to study integration and stability of the solution of constrained mechanical systems. Examples are given to illustrate applications of the result.

关键词： constrained mechanical system skew-gradient system integration stability

Polyaspartic acid mediates the absorption and translocation of mineral elements in tomato seedlings under combined copper and cadmium stress

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2019年第5期18卷 1130-1137页

作者： HU mei-mei DOU Qiao-hui cui Xiu-min LOU yan-hong ZHUGE Yu-ping National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources/College of Resource and Environment Shandong Agricultural University

Polyaspartic acid(PASP)is a nontoxic,biodegradable,environmentally friendly polymer and is widely used as a fertilizer synergist in agricultural *** many old orchards and vegetable gardens,highly fertile soil is often accompanied by severe heavy metal *** present study was designed to investigate mineral element interactions mediated by PASP under copper(Cu)+cadmium(Cd)combined stress to provide reasonable suggestions for scientific fertilization.A pot experiment was conducted in which tomato seedlings served as plant materials.A concentration of 700 mgPASP and foliar spraying application methods were selected based on previous *** treatments were applied:normal soil(control(CK)),Cu+Cd(combined stress),Cu+Cd+PASP,and normal soil+*** plant biomass,root activity,and mineral elements were measured,and these data were analyzed by Data Processing System(DPS)statistical *** results showed that,under Cu+Cd combined stress,PASP promoted stem diameter growth,root activity and chlorophyll content and ultimately increased the biomass of tomato seedlings to different ***,the content of both Cu and Cd and their individual accumulation in plants *** increased the distribution of Cu and Cd in the roots under Cu+Cd combined stress,and the translocation ability from the roots to shoots was significantly *** respect to essential elements,PASP promoted mainly the absorption and translocation of potassium(K),calcium(Ca),and magnesium(Mg),which greatly exerted physiological ***,the variation trends of Cu and Cd under normal soil conditions contrasted with those under stress *** respect to essential elements other than K,Ca,and Mg,PASP mostly restrained their absorption but promoted their *** regulatory mechanism of PASP differed between the combined stress conditions and normal soil *** the combined stress conditions,PASP seemed to mainly promote these

关键词： tomato seedlings polyaspartic acid Cu+Cd combined stress