检索结果-南通市图书馆

Continuity properties for commutators of multilinear type operators on product of certain Hardy spaces

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2014年第6期9卷 1325-1347页

作者： wen.juan LI Qingying XUE School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics andComplex Systems Ministry of Education Beijing 100875 China

Similar to the property of a linear Calderdn-Zygmund operator, a linear fractional type operator Is associated with a BMO function b fails to satisfy the continuity from the Hardy space Hp into Lp for p ≤ 1. Thus, an alternative result was given by Y. Ding, S. Lu and P. Zhang, they proved that [b,Iα] is continuous from an atomic Hardy space Hp b into Lp, where Hp b is a subspace of the Hardy space Hp for n/（n ＋ 1）〈 p ≤ 1. In this paper, we study the commutators of multilinear fractional type operators on product of certain Hardy spaces. The endpoint （Hp1 b1 ×... × HP2, Lp） boundedness for multilinear fractional type operators is obtained. We also give the boundedness for the commutators of multilinear Calderdn-Zygmund operators and multilinear fractional type operators on product of certain Hardy spaces when b ∈ （Lipβ）m（Rn）.

关键词： Multilinear fractional type operator multilinar Calderdn-Zygmundoperator commutator Hardy type space

Local Hamilton type Gradient Estimates and Harnack Inequalities for Nonlinear Parabolic Equations on Riemannian Manifolds

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

Acta Mathematicae Applicatae Sinica 2024年第2期40卷 539-546页

作者： wen WANG Da-peng xie Hui ZHOU School of Mathematics and Statistics Hefei Normal UniversityHefei 230601China

In this paper,we prove a local Hamilton type gradient estimate for positive solution of the nonlinear parabolic equation ut(x,t)=Δu(x,t)+au(x,t) ln u(x,t)+bu^(α)(x,t),on M×(-∞,∞) with α∈R,where a and b are *** ... 详细信息

关键词： nonlinear parabolic equation gradient estimate Harnack inequality

Complex patterns of precipitation and extreme events during 1951-2011 in Sichuan Basin, Southwestern China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第2期15卷 340-356页

作者： ZHOU Xiang-yang LEI wen-juan Guizhou Provincial Key Laboratory of Public Big Data Guizhou University State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University College of Architecture & Environment Sichuan University

Sichuan Basin is located in southwestern China and affected by a complex water vapor （WV） sources. Here, the spatial and temporal patterns of precipitation and extreme events are investigated by six indices of World Meteorology Organization Commission, including annual precipitation total （AP）, maximum daily precipitation （Maxld）, intensity of rainfall over 1 mm/d （IR1）, maximum and mean consecutive dry days （Max CDD, Mean CDD） and coefficient of variance. Based on 24 daily precipitation time series from 1951 to 2o11, Mann-Kendall test is employed to quantify the significant level of these indices, from which the classification of precipitation change and its spatial patterns are obtained. Meanwhile, the probability distributions of these indices are identified by L-moment analysis and the Goodness-of-fit test, and the corresponding values are calculated by theoretical model at different return periods. The results reveal that the western basin displays normal drought： less AP and precipitation intensity while longer drought. The southern basin shows normal increase： larger AP and precipitation intensity but shorter CDD. However, in hilly region of the central basin and the transition zone between basin and mountains, precipitation changes abnormally： increasing both drought （one or both of Mean CDD and MaxCDD） and precipitation intensity （one or both of Maxld and trend of AP is. Probability IR1） no matter what the distribution models also demonstrate the complex patterns： a negative correlation between Maxld and Max CDD in the west （R2≥0.61） while a positive correlation in the east （R2≥0.41） at all return periods. These patterns are induced by the changes in WV sources and the layout of local terrain. The increase of WV in summer and decrease in spring leads to the heavier rainfall and longer drought respectively. The large heat island effect of the basin contributes to a lower temperature in transition zones and more precipitation in the downwind area. These resul

关键词： Extreme precipitation events Climatechange Sichuan Basin Trend analysis Probability distribution

Experimental study on large wood filtration performance by herringbone water-sediment separation structure

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2017年第2期14卷 269-281页

作者： xie Xiang-ping WEI Fang-qiang YANG Hong-juan xie Tao Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Key Laboratory of Mountain Hazards and Earth Surface Process Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China Chongqing Jiao Tong University Chongqing 400074China

A herringbone water-sediment separation structure(hereinafter referred to as "herringbone structure") has been shown to be effective in separating coarse inorganic debris; however, less is known regarding the large wood(LW) filtration effect in this structure. This paper presents preliminary research on the wood filtration effect of the herringbone structure based on physical model *** results show that the herringbone structure exhibited effective performance in large wood size segregation, with a 100% component filtration rate for LW that diameter(D) larger than ribbed beam opening width(a). The total filtration rate also exceeded 80% when the Fraud number(Fr) is larger than 2.64 and increased with the increase of Fr. After exceeding Frmax, total filtration rate would be decreased due to overflow. Beside flow condition,structure parameters influence significantly on LW filtration rate. We attempt to explain the filtration process via particle contact trajectory and particle movement trajectory. The inclined angle of ribbed beam(γ) contributed the most variation to the filtration rate via influencing the coincidence with particle contact trajectory and particle movement trajectory. The high sensitivity coefficient of ribbed beam(θ) under relatively low Fr conditions implies remarkable influences on LW filtration effects by causing clogging problem. The ribbed beam opening width(a) together with LW diameter(D) influenced the size segregation performance.

关键词： Debris flow Large wood Herringbone water-sediment separation structure Filtration effect

An assessment method of annual climatic status in China using extreme climate indices:2021 as an example

在线全文

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2022年第6期13卷 868-874页

作者： Zeng-Yuan GUO Li-juan CHEN Bing xie Climate Studies Key Laboratory National Climate CenterChina Meteorological AdministrationBeijing 100081China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjing 210044China

A proper assessment of annual climatic status(ACS)is conducive to rationally formulating disaster prevention and mitigation *** former definition of ACS lacks either information on extreme climate or an intuitive grade feature service to the *** ACS defined in the National Standard of the People's Republic of China(GBACS)only considers the accumulated climate effects of each weighted 10-d temperature/precipitation anomaly in a *** global warming,the losses caused by extreme climate events often have a significant impact on the grades of ACS,but this impact cannot be reasonably reflected by *** study proposed the assessment of ACS using extreme climate indices(extreme climate-based ACS(ECACS))and compared it with *** results indicated that GBACS and ECACS can be used to evaluate the ACS from different *** ECACS is an important supplement to the GBACS,especially considering the years with frequently occurring extreme climate *** sum of GBACS and ECACS is a reasonable and comprehensive way to evaluate the *** empirical orthogonal function(EOF)analysis indicated a uniform mode(EOF1)and a dipole mode(EOF2)in GBACS and ECACS in *** interannual variation characteristics of ECACS in northern and southern China(EOF2 pattern)are consistent with real climate features,which is conducive to providing better and more detailed regional information in the ACS forecast *** results have essential instructive and application value for ACS assessment and government decision making.

关键词： Extreme climate indices Annual climatic status Temperature Precipitation

Experimental study on combustion characteristics of Chinese RP-3 kerosene

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

Chinese Journal of Aeronautics 2016年第2期29卷 375-385页

作者： Ma Hongan xie Maozhao Zeng wen Chen Baodong School of Energy and Power Engineering Dalian University of Technology Liaoning Key Laboratory of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace University

In order to illustrate the combustion characteristics of RP-3 kerosene which is widely used in Chinese aero-engines, the combustion characteristics of RP-3 kerosene were experimentally inves- tigated in a constant volume combustion chamber. The experiments were performed at four different pressures of 0.1 MPa, 0.3 MPa, 0.5 MPa and 0.7 MPa, and three different temperatures of 390 K, 420 K and 450 K, and over the equivalence ratio range of 0.6-1.6. Furthermore, the laminar combus- tion speeds of a surrogate fuel for RP-3 kerosene were simulated under certain conditions. The results show that increasing the initial temperature or decreasing the initial pressure causes an increase in the laminar combustion speed of RP-3 kerosene. With the equivalence ratio increasing from 0.6 to 1.6, the laminar combustion speed increases initially and then decreases gradually. The highest laminar combustion speed is measured under fuel rich condition （the equivalence ratio is 1.2）. At the same time, the Markstein length shows the same changing trend as the laminar com- bustion speed with modification of the initial pressure. Increasing the initial pressure will increase the instability of the flame front, which is established by decreased Markstein length. However, different from the effects of the initial temperature and equivalence ratio on the laminar combustion speed, increasing the equivalence ratio will lead to a decrease in the Markstein length and the stability of the flame front, and the effect of the initial temperature on the Markstein length is unclear. Further- more, the simulated laminar combustion speeds of the surrogate fuel agree with the corresponding experimental datas of RP-3 kerosene within ~10% deviation under certain conditions.

关键词： Combustion mechanism Combustion stability Laminar combustion speed Markstein length RP-3 kerosene

Laws of Large Numbers of Negatively Correlated Random Variables for Capacities

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2011年第4期27卷 749-760页

作者： wen-juan LI Zeng-jing CHEN School of Mathematics Shandong University Jinan 250100 China

Our aim is to present some limit theorems for capacities. We consider a sequence of pairwise negatively correlated random variables. We obtain laws of large numbers for upper probabilities and 2-alternating capacities, using some results in the classical probability theory and a non-additive version of Chebyshev＇s inequality and Boral-Contelli lemma for capacities.

关键词： law of large numbers 2-alternating capacity negatively correlated random variables upper probability

Wideband radar detector based on characteristic parameters of echoes

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2019年第5期30卷 897-904页

作者： CHANG Jiayun FU Xiongjun JIANG wen xie Min School of Information and Electronics Beijing Institute of Technology

The statistical characterization of radar range cells with the target signals is much more distinct than that of the range cells with noise-only ***,the quasi-optimal detection principle based on the characteristic parameters of echo signals is adopted to develop a detector of range-spread targets in Gaussian ***,the characteristic parameters of the return signals in the entire range profiles of radar are ***,the clustering analysis of the characteristic parameter matrix is discussed to extract the test statistic of ***,the probabilities of detection and false alarm of the proposed detector are *** analysis shows that the proposed detector does not need the prior knowledge about the spatial distribution of the target scattering centers in practical scenarios,and it is simple and robust even in low signal-to-noise ratio(low-SNR)*** Carlo(MC)simulations reveal that the detection performance of the proposed detector outperforms the conventional detectors.

关键词： wideband radar mathematical statistics characteristic parameter clustering analysis

Bifurcation behaviors of catalytic combustion in a micro-channel

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2008年第1期17卷 84-89页

作者： wen Zeng Maozhao xie Hongan Ma Wei Xu School of Aero-engine and Energy Engineering Shenyang Institute of Aeronautical Engineering Shenyang 110034China School of Energy and Power Engineering Dalian University of Technology Dalian 116024 China

Bifurcation analysis of ignition and extinction of catalytic combustion in a short micro-channel is carded out with the laminar flow model incorporated as the flow model. The square of transverse Thiele modulus and the residence time are used as bifurcation parameters. The influences of different parameters on ignition and extinction behavior are investigated. It is shown that all these parameters have great effects on the bifurcation behaviors of ignition and extinction in the short micro-channel. The effects of flow models on bifurcation behaviors of combustion are also analyzed. The results show that in comparison with the flat velocity profile model, for the case of the laminar flow model, the temperatures of ignition and extinction of combustion are higher and the unsteady multiple solution region is larger.

关键词： catalytic combustion bifurcation theory short monolith