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UNIFORMLY A POSTERIORI ERROR ESTIMATE FOR THE FINITE ELEMENT METHOD TO A MODEL PARAMETER DEPENDENT PROBLEM

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Journal of Computational Mathematics 2008年第5期26卷 716-727页

作者： Yiran Zhang jun hu LMAM and School of Mathematical Sciences Peking University Beijing 100871 China

This paper proposes a reliable and efficient a posteriori error estimator for the finite element methods for the beam problem. It is proved that the error can be bounded by the computable error estimator from above an... 详细信息

关键词： The beam problem A posteriori error estimator Finite element method.

Anti-aggregation dispersion of ultrafine particles by electrostatic technique

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Chinese Science Bulletin 2001年第9期46卷 740-743页

作者： REN jun LU Shouci SHEN jian YU Chunhong hu Boxing Center of Research on Surface and Interface Chemical Engineering and Technology Nanjing UniversityNanjing 210093China College of Resources Engineering University of Science and Technology BeijingBeijing 100083China

The dispersion of ultrafine particles in the air can be achieved by mechanical method or surface modification. In this work, the electrostatic technique was first employed for anti-aggregation of ultrafine particles. When the relative humidity of the air is within the region of 70%-75%, effective storage time of ultrafine particles can reach 72 h after treatment by the electrostatic technique. The experimental results showed that this technique imparted ultrafine particles much more pronounced anti-aggregation property. In the dry air, the critical diameter of ultrafine particles anti-aggregated by the electrostatic technique is the function of particle property and charging field intensity. The critical diameter is inversely proportional to the square of the charging field intensity.

关键词： ultrafone particle anti-aggregation dispersion electrostatic technique dispersion degree.

Innate and adaptive immune escape mechanisms of hepatitis B virus

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World Journal of Gastroenterology 2022年第9期28卷 881-896页

作者： hua-jun Zhao Yi-Fei hu Qiu-Ju Han jian Zhang Institute of Immunopharmaceutical Sciences School of Pharmaceutical SciencesShandong UniversityJinan 250012Shandong ProvinceChina

Chronic hepatitis B virus(HBV)infection is an international health problem with extremely high mortality and morbidity *** current clinical chronic hepatitis B(CHB)treatment strategies can partly inhibit and eliminate HBV,viral breakthrough may result due to non-adherence to treatment,the emergence of viral resistance,and a long treatment *** CHB infection arises as a consequence of complex interactions between the virus and the host innate and adaptive immune ***,understanding the immune escape mechanisms involved in persistent HBV infection is important for designing novel CHB treatment strategies to clear HBV and achieve long-lasting immune *** review details the immunological and biological characteristics and escape mechanisms of HBV and the novel immune-based therapies that are currently used for treating HBV.

关键词： Hepatitis B virus Innate immunity Adaptive immunity Immune tolerance Therapeutic strategy

Modeling Soil Organic Carbon Storage and Its Dynamics in Croplands of China

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维普期刊数据库

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Agricultural Sciences in China 2010年第5期9卷 704-712页

作者： TANG hua-jun QIU jian-jun WANG Li-gang LI hu LI Chang-sheng Eric van Ranst Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 P.R.China Institute for the Study of Earth Oceans and Space University of New Hampshire Durham NH 03824 USA Department of Geology and Soil Science (WE13)/Laboratory of Soil Science Ghent University Gent B-9000 Belgium

Soil organic carbon （SOC） is one of the centre issues related to not only soil fertility but also environmental safety. Assessing SOC dynamics in croplands has been a challenge in China for long due to the lack of appropriate methodologies and data sources. As an alternative approach for studying SOC dynamics, process-based models are adopted to meet the needs. In this paper, a process-based model, DeNitrification-DeComposition （DNDC）, was applied to quantify the SOC storage and the spatial distribution in croplands of China in 2003, with the support of a newly compiled county-level soil/ climate/land use database. The simulated results showed that the total SOC storage in the top layer （0-30 cm） of the 1.18 × 10^8 ha croplands of China is 4.7-5.2 Pg C in 2003 with an average value of 4.95 Pg C. The SOC storage in the northeastern provinces （1.3 Pg C） accounts for about 1/4 of the whole national totals due to their dominantly fertile soils with high organic matter content. SOC density ranges from 3.9 to 4.4 kg C m 2, with an average of 4.2 kg C m^-2, a level is much lower than the world average level. The model results also indicated that high rates of SOC losses occurred in the croplands with the most common cropping patterns in China as like single soybean 〉 maize 〉 paddy 〉 cotton 〉 winter wheat and corn rotation. The results reported in this paper showed that there was still a great potential for improving SOC status in most croplands of China by adopting proper farming practices and land-use pattern. Therefore, long-term policy to protect SOC is urgently needed.

关键词： China cropland DNDC model soil organic carbon

Overexpression of galactinol synthase 1 from Solanum commersonii(ScGolS1) confers freezing tolerance in transgenic potato

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Horticultural Plant Journal 2023年第3期9卷 541-552页

作者： Feiyan He jianfei Xu Yinqiao jian Shaoguang Duan jun hu Liping Jin Guangcun Li State Key Laboratory of Vegetable Biobreeding/Ministry of Agriculture and Rural Affairs Key Laboratory of Biology and Genetic Improvement of Tuber and Root Crop/Institute of Vegetables and Flowers Chinese Academy of Agricultural SciencesBeijing 100081China

Potato(Solanum tuberosum L.) is the fourth largest food crop in the world. Low temperatures cause serious damage to potato plants every year, and freezing tolerance has become a hot spot in potato research. Galactinol synthase(GolS) is a key enzyme in the synthesis of raffinose family oligosaccharides(RFOs), and plays an important role in the response of plants to abiotic stress. In this study, the ScGolS1 gene from Solanum commersonii was cloned and introduced into the S. tuberosum cultivars 'Atlantic' and 'Desiree' via Agrobacterium-mediated transformation. Phenotyping assays showed that overexpression of ScGolS1 could significantly improve freezing tolerance in transgenic potato *** physiological and biochemical experiments showed that the transgenic lines had lower relative conductivity, malondialdehyde content,and 3,3-diaminobenzidine staining and a higher plant survival rate compared with wild type(WT) under cold stress. Moreover, the C-repeat binding factors(CBF1, CBF2 and CBF3), the downstream cold-responsive genes COR413 and COR47, and the ethylene-responsive factor(ERF)transcription factor genes ERF3, ERF4 and ERF6, which function in the ethylene signaling pathway, were all induced by freezing treatment and expressed at higher levels in the ScGolS1 overexpression lines compared with WT. Besides, the expression of some genes such as MIPS, STS and RS from the RFO metabolic pathway was up-regulated under cold stress, resulting in changes in the content of some soluble sugars. This indicated that ScGolS1 overexpression altered the sugar composition and enhanced freezing tolerance in transgenic potato by inducing the ethylene and CBF signaling pathways. These results provided theoretical support and genetic resources for freezing tolerance breeding in potato.

关键词： Solanum commersonii ScGolS1 Freezing tolerance RFOs ERF CBF

Distribution, failure risk and reinforcement necessity of check-dams on the Loess Plateau: a review

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Journal of Mountain Science 2021年第2期18卷 499-509页

作者： GUO Wen-zhao WANG Wen-Long XU Qiang hu jian-jun Zhu Li-li State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Water and Soil ConservationNorthwest A&F UniversityYangling 712100China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China Key Laboratory of Mountain Hazards and Earth Surface Processes Chinese Academy of SciencesChengdu 610059China Xi'an Planning Design&Research InstituteUpper and middle Yellow River BureauYellow River Conservancy CommissionMinistry of Water ResourcesXi'an 710021China

Check-dams are the most important measure to control the soil and water loss in highly erodible catchments on the Chinese Loess *** on the data of check-dams from 1950 to 2014,our study roundly analyzed the regional distribution,function and the problems of check-dams on the Loess Plateau.A total of 17,094 check-dams with a storage capacity of over 100,000 m^(3) and an average density of 0.027 counts km^(-2) were installed on the Loess ***-dams’densities varied greatly in the Qinghai Province,Gansu Province,Ningxia hui Autonomous Region,Inner Mongolia Autonomous Region,Shaanxi Province,Shanxi Province and Henan *** highest density of check-dams reached 0.088 counts km^(-2) in Shaanxi Province,whereas the lowest density of check-dams was only 0.005 counts km^(-2) in Qinghai ***,after decades of operation,3025 large check-dams and 2257 medium check dams are dangerous and have security risks,which are seriously threatening downstream *** dangerous rate of checkdams is ***,the check-dams in Shanxi and Qinghai Province have the highest dangerous rates,with both exceeding 53%.Therefore,there is an urgent need for carrying out reinforcement of the dangerous *** results are helpful to policymakers to extend and develop check-dams.

关键词： Check-dam Soil erosion Sediment Gully Dam failure Chinese Loess Plateau

Empirical Likelihood Ratio Confidence Interval for Positively Associated Series

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Acta Mathematicae Applicatae Sinica 2007年第2期23卷 245-254页

作者： jun-jian Zhang College of Applied Sciences Beijing University of Technology Beijing 100022 China College of Mathematics Guangxi Normal University Guilin 541004 China

Empirical likelihood is discussed by using the blockwise technique for strongly stationary, positively associated random variables. Our results show that the statistics is asymptotically chi-square distributed and the... 详细信息

关键词： Empirical likelihood positive association blockwise confidence interval

Modeling the Impacts of Soil Organic Carbon Content of Croplands on Crop Yields in China

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Agricultural Sciences in China 2009年第4期8卷 464-471页

作者： QIU jian-jun WANG Li-gang LI hu TANG hua-jun LI Chang-sheng Eric Van Ranst Key Laboratory of Resources Remote Sensing and Digital Agriculture Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences (CAAS) Beijing 100081 P.R. China Institute for the Study of Earth Ocean and Space University of New Hampshire Durham NH 03824 USA Department of Geology and Soil Science (WEI3) Laboratory of Soil Science Ghent University Krijgslaan 281 (S8) B-9000 Gent Belgium

This study quantified the impacts of soil organic carbon （SOC） content on the grain yield of crops using a biogeochemical model （DNDC, denitrification-decomposition）. Data on climate, soil properties, and farming management regimes of cropping systems were collected from six typical agricultural zones （northeast, north, northwest, mid-south, east and southwest regions of China, respectively） and integrated into a GIS database to support the model runs. According to the model, if the initial SOC content in the cropland was increased by 1 g C kg^-1, the crop yield may be increased by 176 kg ha^-1 for maize in the northeast region, 454 kg ha^-1 for a maize-wheat rotation in the north region, 328 kg ha^-1 for maize in the northwest region, 185 kg ha^-1 for single-rice in the mid-south region, 266 kg ha^-1 for double-rice in east region, and 229 kg ha^-1 for rice and wheat rotation in southwest region. There is a great potential for enhancing the crop yield by improving the SOC content in each region of China.

关键词： soil organic carbon grain yield carbon sequestration DNDC model

Active Fault Tolerant Nonsingular Terminal Sliding Mode Control for Electromechanical System Based on Support Vector Machine

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 189-203页

作者： jian hu Zhengyin Yang jianyong Yao School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China

Effective fault diagnosis and fault-tolerant control method for aeronautics electromechanical actuator is concerned in this *** borrowing the advantages of model-driven and data-driven methods,a fault tolerant nonsingular terminal sliding mode control method based on support vector machine(SVM)is proposed.A SVM is designed to estimate the fault by off-line learning from small sample data with solving convex quadratic programming method and is introduced into a high-gain observer,so as to improve the state estimation and fault detection accuracy when the fault *** state estimation value of the observer is used for state reconfiguration.A novel nonsingular terminal sliding mode surface is designed,and Lyapunov theorem is used to derive a parameter adaptation law and a control *** is guaranteed that the proposed controller can achieve asymptotical stability which is superior to many advanced fault-tolerant *** addition,the parameter estimation also can help to diagnose the system faults because the faults can be reflected by the parameters *** comparative simulation and experimental results illustrate the effectiveness and advancement of the proposed controller compared with several other main-stream controllers.

关键词： Aeronautics electromechanical actuator Fault tolerant control Support vector machine State observer Parametric uncertainty