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Developing an Instantaneous Response Surface Method t-IRS for Time-Dependent Reliability Analysis

Acta Mechanica Solida Sinica 2019年第4期32卷 446-462页

作者： junxiang li Jianqiao Chen Junhong Wei Xiaosheng Zhang Ben Han Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China

In practical engineering, many uncertain factors in loading or degradation of material properties may vary with time. Stochastic process modeling constitutes a suitable approach for describing these time-dependent uncertainties. By adopting this approach, however, the timedependent reliability calculation is a great challenge owing to the complexity and the huge computational burden. This paper presents a new instantaneous response surface method t-IRS for time-dependent reliability analysis. Different from the adaptive extreme response surface approach, the proposed method does not need to build and update surrogate models separately at each time node. It first uses the expansion optimal linear estimation method to discretize the stochastic processes into a set of independent standard normal variables together with some deterministic functions of time. Time is then treated as an independent one-dimensional variable. Next, initial samples are generated by Latin hypercube sampling, and the corresponding response values are calculated and utilized to construct an instantaneous response surrogate model of the Kriging type. The active learning method is applied to update the Kriging surrogate model until satisfactory accuracy is achieved. Finally, the instantaneous response surrogate model is used to compute the time-dependent reliability via Monte Carlo simulation. Four case studies are utilized to demonstrate the effectiveness of the ^-IRS method for time-dependent reliability analysis.

关键词： Time-dependent reliability Stochastic process Instantaneous response surface method i-IRS Expansion optimal linear estimation method Kriging surrogate model

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The combination of gut microbiota-depleted treatment and fecal microbiota transplantation is an important strategy to verify the efficacy of Traditional Chinese Medicine though modulation of gut dysbiosis

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Journal of Traditional Chinese Medicine 2024年第1期44卷 222-223页

作者： XING Yunqi li junxiang YUAN Yali MAO Tangyou Gastroenterology Department Dongfang HospitalBeijing University of Chinese MedicineBeijing 100078China Department of Hepatology Yueyang Hospital of Integrated Traditional Chinese and Western MedicineShanghai University of Traditional Chinese MedicineShanghai 201203China

To the Editors:We read with great interest the study recently published by Sun et al 1 entitled“Electroacupuncture at Tianshu(ST25)and Zusanli(ST36)alleviates stress-induced irritable bowel syndrome in mice by modulating gut microbiota and corticotropin-releasing factor”in which the microbial details of electroacupuncture(EA)-induced protection in irritable bowel syndrome(IBS)were investigated.

关键词： releasing treatment details

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Current status and future directions of the Tibetan Plateau ecosystem research

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Science Bulletin 2019年第7期64卷 428-430页

作者： Yangjian Zhang Yixuan Zhu junxiang li Yao Chen Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences College of Resources and Environment University of Chinese Academy of Sciences

The Tibetan Plateau (TP) encompasses Xizang and Qinghai and parts of northern Yunnan and Sichuan provinces, with a total area of circa 2.6 millions km2. The 2013 satellite data showed that grasslands, forests, wetlands, agricultural lands, and deserts account for 60%, 7.7%, 1.4%, 0.3%, and 30%, respectively, of total TP land (1)Due to its existence in dry, high altitude and cold environments, the TP ecosystem is extremely vulnerable to global climate change and studies on the TP ecosystem can be utilized as a pre-warning for other ecosystems.

关键词： Current status and future directions of the Tibetan Plateau ecosystem research TP

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Vegetation classification of East China with multi-temporal NOAA-AVHRR data

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Frontiers in Biology 2006年第3期1卷 303-309页

作者： li junxiang DA liangjun WANG Yujie SONG Yongchang Department of Environmental Science East China Normal UniversityShanghai 200062China

East China lies in the subtropical monsoon cli-matic zone and is dominated by subtropical evergreen broad-leaved forests,a unique vegetation type mainly dis-tributed in East Asia with the largest distribution in *** is important to be able to monitor and estimate forest biomass and production,regional carbon storage,and global climate change impacts on these important vegetation *** this paper,we used coarse resolution remote sensing data to identify the vegetation types in East China and developed a map of the spatial distribution of vegetation types in this *** maximum normalized difference vegeta-tion index(NDVI)composite images(acquisition time span of 7 months from February to August),which were derived from 10 days National Oceanographic and Atmospheric Administration(NOAA)Advanced Very High Resolution Radiometer(AVHRR)channel 1 and channel 2 observa-tions,an unsupervised classification method,and the ISODATA algorithm were employed to identify the vegeta-tion *** reduce the dimensions of the dataset resulted in a total of 28 spectral clusters of land-cover of which two clusters were urban/bare soil and water,the images were processed using principal component analysis(PCA).The 26 remaining spectral clusters were merged into six vegeta-tion types using the Chinese vegetation taxonomy system:evergreen broad-leaved forest,coniferous forest,bamboo forest,shrub-grass,aquatic vegetation,and agricultural *** spatial distribution and areal extent for the coniferous forests,shrub-grass,evergreen broad-leaved for-ests,and agricultural vegetation were calculated and com-pared with the Vegetation Atlas of China at a 1:1,000,000 *** spatial accuracy and the area accuracy for conif-erous forests,shrub-grass,evergreen broad-leaved forests,and agricultural vegetation were 79.2%,91.3%,68.2%and 95.9%and 92.1%,95.9%,63.8%and 90.5%,*** spatial accuracy and area accuracy of the bamboo forest were 28.7%and 96.5%,respectively

关键词： vegetation classification remote sensing NDVI principal component analysis East China

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Neurogenic differentiation of human umbilical cord mesenchymal stem cells on aligned electrospun polypyrrole/ polylactide composite nanofibers with electrical stimulation

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Frontiers of Materials Science 2016年第3期10卷 260-269页

作者： Junfeng ZHOU liang CHENG Xiaodan SUN Xiumei WANG ShouhongJIN junxiang li Qiong WU Key Laboratory of Advanced Materials of Ministry of Education of China School of Materials Science and Engineering Tsinghua University Beijing 100084 China School of life Sciences Tsinghua University Beijing 100084 China

Adult central nervous system （CNS） tissue has a limited capacity to recover after trauma or disease. Recent medical cell therapy using polymeric biomaterial- loaded stem cells with the capability of differentiation to specific neural population has directed focuses toward the recovery of CNS. Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal cells. Here we report on the fabrication of an electrospun polypyrrole/polylactide composite nanofiber film that direct or determine the fate of mesenchymal stem cells （MSCs）, via combination of aligned surface topography, and electrical stimulation （ES）. The surface morphology, mechanical properties and electric properties of the film were characterized. Comparing with that on random surface film, expression of neurofilament-lowest and nestin of human umbilical cord mesenchymal stem cells （huMSCs） cultured on film with aligned surface topography and ES were obviously enhanced. These results suggest that aligned topography combining with ES facilitates the neurogenic differentiation of huMSCs and the aligned conductive film can act as a potential nerve scaffold.

关键词： human umbilical cord mesenchymal stem cells neurogenic differentiation conductive composite film electrospun nanofibers electrical stimulation

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Simulation Method and Feature Analysis of Shutdown Pressure Evolution During Multi-Cluster Fracturing Stimulation

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Energy Engineering 2024年第1期121卷 111-123页

作者： Huaiyin He Longqing Zou Yanchao li Yixuan Wang junxiang li Huan Wen Bei Chang lijun liu Shale Gas Exploration and Development Department CNPC Chuanqing Drilling Engineering Co.Ltd.Chengdu610051China College of Energy Chengdu University of TechnologyChengdu610059China

Multistage multi-cluster hydraulic fracturing has enabled the economic exploitation of shale reservoirs,but the interpretation of hydraulic fracture parameters is *** pressure signals after pump shutdown are influenced by hydraulic fractures,which can reflect the geometric features of hydraulic *** shutdown pressure can be used to interpret the hydraulic fracture parameters in a real-time and cost-effective *** this paper,a mathematical model for shutdown pressure evolution is developed considering the effects of wellbore friction,perforation friction and fluid loss in *** efficient numerical simulation method is established by using the method of *** on this method,the impacts of fracture half-length,fracture height,opened cluster and perforation number,and filtration coefficient on the evolution of shutdown pressure are *** results indicate that a larger fracture half-length may hasten the decay of shutdown pressure,while a larger fracture height can slow down the decay of shutdown pressure.A smaller number of opened clusters and perforations can significantly increase the perforation friction and decrease the overall level of shutdown pressure.A larger filtration coefficient may accelerate the fluid filtration in the fracture and hasten the drop of the shutdown *** simulation method of shutdown pressure,as well as the analysis results,has important implications for the interpretation of hydraulic fracture parameters.

关键词： Multistage multi-cluster hydraulic fracturing pump shutdown pressure feature analysis numerical simulation

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Grazing alters environmental control mechanisms of evapotranspiration in an alpine meadow of the tibetan Plateau

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Journal of Plant Ecology 2019年第5期12卷 834-845页

作者： Tingting An Mingjie Xu Tao Zhang Chengqun Yu Yingge li Ning Chen Jiaxing Zu junxiang li Juntao Zhu Yi Sun Tingting Zhao Guirui Yu College of Agronomy Shenyang Agricultural UniversityShenyang 110866China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Peking University Shenzhen Graduate School Shenzhen 518055China

Aims Evapotranspiration(Et)is an important component of the terrestrial water cycle and is easily affected by external disturbances,such as climate change and *** Et responses to grazing is instructive for determining grazing activity and informative for understanding the water *** this study utilized 2 years(2014 and 2017)of eddy covariance data to test how grazing regulated Et for an alpine meadow ecosystem on the tibetan Plateau(tP)by path *** Findings Radiation dominated Et with a decision coefficient of 64-74%.the soil water content(SWc)worked as the limiting factor in the fenced ***,in the grazing site,the limiting factor was the vapor pressure deficit(VPD).Grazing had large effects on Et because it greatly affected the water *** SWc and VPD were enhanced by 14.63%and 4.36%in the grazing site,***,sufficient water was supplied to Et,especially during drought,and strengthened the transpiration *** a result,a favorable micrometeorological environment was created for *** shifted the limiting factor of Et from the SWc to VPD,which weakened the limiting effect of the water conditions on Et and advanced the Et peak *** addition,grazing altered the compositions of Et by changing the community structure,which directly resulted in an increased *** summary,grazing enhanced Et through altering the community structure and micrometeorological *** findings of this study further improve our understanding of the driving mechanisms of grazing on Et and will improve our predictions for the global water cycle.

关键词： grazing evapotranspiration environmental factors alpine meadow path analysis

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Hewei Jiangni granule alleviates visceral hypersensitivity in a rat model of non-erosive reflux disease via transient receptor potential channel signaling

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Journal of Traditional Chinese Medical Sciences 2020年第2期7卷 162-170页

作者： Jiali liu Fushun Kou Xiang Tan Yi Dai Chune Xie Xiaohong li Lei Shi Tangyou Mao Xiaojun Shi junxiang li Graduate School of Beijing University of Chinese Medicine Beijing100029China Department of Gastroenterology Dongfang HospitalBeijing University of Chinese MedicineBeijing100078China Department of Pharmacotherapy and Oriental Medicine School of PharmacyHyogo University of Health SciencesHyogo650-8530Japan School of life Sciences Beijing University of Chinese MedicineBeijing102488China

Objective:To uncover the underlying mechanism of Hewei Jiangni granule(HWJNG)on non-erosive reflux disease(NERD)treatment by examining histological changes,gastrointestinal neurochemicals release and visceral hypersensitivity-related receptor expression in NERD model ***:A NERD rat model was established via a combination of basal sensitization and acid *** treatments at different doses were then *** changes to tissues,mast cell(MC)activation,serum levels of esophageal visceral hypersensitivity-related neurochemicals,and transient receptor potential(TRP)receptor mRNA and protein levels were ***:Compared with the control group,the expression of tryptase in MCs,the changes of intercellular space,and the serum levels of substance P(SP),calcitonin gene-related peptides(CGRP)and proteinaseactivated receptor 2(PAR2)increased in the model group(all Plia(DRG)of the model group(P=.030&P=.013),and the expression of TRP melastatin channel subfamily member 8(Trpm8)mRNA decreased in the esophagus of model group(P<.01).The level of esophageal TRPV1 protein increased in the model group(P<.01)and the level of TRPM8 protein decreased in esophagus and DRG of the model group(both P<.05).Compared with the model group,the serum levels of SP,CGRP,and PAR2 in the mediumdose HWJNG group showed significant decreases(all P<.05).The expression of Trpv1 mRNA in esophagus and DRG of the HWJNG groups and the Omeprazole group remarkably decreased(all P<.05),as was the expression of Trpm8 mRNA in esophagus of the HWJNG groups(all P<.05).Conclusion:HWJNG alleviated visceral hypersensitivity in NERD model rats by regulating TRP-mediated *** results indicate that HWJNG has potential as a therapeutic agent for NERD.

关键词： Hewei jiangni granule Non-erosive reflux disease Esophageal visceral hypersensitivity Transient receptor Neurochemicals

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A Maneuver-Prediction Method Based on Dynamic Bayesian Network in Highway Scenarios

A Maneuver-Prediction Method Based on Dynamic Bayesian Netwo...

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第30届中国控制与决策会议

作者： junxiang li Xiaohui li Bohan Jiang Qi Zhu College of Mechatronic Engineering and Automation National University of Defense Technology

The accurate maneuver prediction for dynamic vehicles can enhance driving safety in complex *** paper presents a maneuver prediction method for dynamic vehicles in highway scenarios. The method effectively combines multi-frame vehicle states, road structures and interactions among vehicles. With a novel extraction algorithm of environment feature, the method infers the probability of each driving maneuver by using a Dynamic Bayesian Network. The experimental results demonstrate that our method can predict lane-change maneuvers at least 2 seconds before they occur in real environments with an accuracy of 84.9%.

关键词： Autonomous driving maneuver prediction feature extraction Dynamic Bayesian Network

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灰色离散大系统稳定性的代数判据(英文)

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南开大学学报（自然科学版） 2006年第3期39卷 110-112页

作者：李君湘天津大学理学院天津300072

利用一般离散大系统零解稳定性的Lyapunov分解理论,结合区间矩阵的概念,讨论了线性灰色离散大系统和具有非线性扰动项的灰色离散大系统的稳定性问题,得到了若干稳定性的充分判据．

关键词：灰色离散大系统 Lyapunov函数渐近稳定分解理论孤立子

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