三阶时滞泛函微分方程解的渐近性     

庾建设 《湖南农业大学学报(自然科学版)》1990,17(3)

本文讨论一类三阶时滞泛函微分方程解的渐近性质,给出了若干解的有界性及解趋于零的判定准则.  相似文献   

一类时滞微分系统有界解的收敛性     

黄立宏韦志坚  易泰山 《湖南农业大学学报(自然科学版)》2005,32(6)

研究了一类时滞微分系统解的渐近性态．在一些比已有文献通常附加的局部李普希兹条件更弱的条件下，证明了此系统的每个有界解趋于某平衡态．我们的结果推广了已有的一些结论．  相似文献   

Attractors of Partly Dissipative Reaction-diffusion Equation on Rn     

ZHAO lei-n  ZHANG Xing-you  XING Ting-li 《保鲜与加工》2007,(7):144-147151

We discuss the problem related to the long time behavior of solutions of the partly dissipative reaction-diffusion equations in unbounded domain,and prove the existence of the compact attractors.The coefficient of the reaction-term depends on space variables,which extend Wang B and Marion M's results.  相似文献   

Asymptotic Attractors of the Nonlinear Evolution Equation in Bounded Domain     

ZHAO Lei-n  ZHANG Xing-you  XING Ting-li 《保鲜与加工》2007,(2):136-138148

The basic principle of infinite-dimensional dynamic system is to try to reduce the original infinite-dimensional system to an infinite-dimensional system. However,due to the unknown structure of the reduced system, it is difficult to describe its dynamical behaviour. To overcome this difficulty, the idea of approximate inertial manifolds is introduced, for NSE, the existence of AIM was studied, it is shown that the global attractor lies within a neighborhood of the graph of an Lipschitz function by the squeezing property. In this paper, by constructing a finite dimensional solution sequence, we will prove that it tends to the global attractor, theoretically, this provides a metod of constructing the asymptotic attractors, theoretically, this provides a method of constructing the asymptotic attractors for the evolution equations.  相似文献   

A method of production data analysis for multi-fractured horizontal well in shale gas reservoir     

WANG Junlei  WEI Yunsheng  CHENG Minhua  LUO Wanjing 《保鲜与加工》2014,(1):102-109

Production data analysis is an effective method of evaluating gas in place, parameters of reservoir and hydraulic fractures. Current model of production data analysis fails to make sense because of the existence of absorption, multi-fracturing, and stimulated reservoir volume (SRV). Considering the effect of desorption, fracture interacting and closed boundary, the authors calculate the productivity of multi-fractured horizontal well in shale gas by Laplace transform and pressure superposition principle. Then theoretical charts of Agarwal-Gardner production decline curves are presented by employing new definition of dimensionless material balance time and dimensionless production, which is based on asymptotic approximations. The result shows that Agarwal-Gardner curves can be divided into two parts where they are scattered in early transient period, and where their shape was influenced by parameters relevant to adsorption, position of each fracture and reservoir geometry, and then drawn to Arps harmonious decline in pseudo steady state period. Reservoir parameters, hydraulic fracture characteristics and gas in place are evaluated by using the type curve matching with actual production data.  相似文献   

一类应力-强度模型结构可靠度的估计     

龙兵 《长江大学学报》2007,4(3):11-13

考虑了应力服从三维GBVE分布,强度服从指数分布的应力-强度模型,分别在部分应力参数未知和强度参数未知的情况下给出了该模型在并联情况下结构可靠度的估计,并讨论了其性质。  相似文献   

自动分布阈值图像多目标分割算法     

罗三定  张中良 《湖南农业大学学报(自然科学版)》2008,35(2):77-80

提出了一种有实际背景的最小费用箱子覆盖问题──每个物品有长度和费用2个参数.针对局外最小费用箱子覆盖问题,给出了一个求解该问题的最坏情况渐近性能比为1/2算法C-FF1.同时给出了一个求解该问题的局内算法C-FF2,其绝对性能比为1/2,并证明了不存在绝对性能比大于1的算法.  相似文献   

Analysis of Reliability of the Harary Graph     

He Zhongshi  Yang Xiaofan  Yi Dong 《保鲜与加工》1996,(6):14-19

When the vertices fail independently with each other by a constant probability,the reliability of a sraph is defined to be the probability that the graph results from deleting thefailed venices together with the incidence edges is connected. The Harary graph,a class of graphswith the best connectivity is considered in this paper,the bound of it's reliability is obtained,and theasymptotic property of reliability is also analysed.  相似文献   

Using compiled species lists to make biodiversity comparisons among regions: A test case using Oregon butterflies     

William F. Fagan  Peter M. Kareiva 《Biological conservation》1997,80(3):249-259

We explore two methods that correct for differential sampling effort when estimating the true number of species in a region based on samples such as those typically recorded in museum or conservation databases. The two methods are: (1) a phenomenological model that relies on a saturating sampling curve; and (2) a model based on a lognormal distribution of species abundances. We test these methods using a database for the butterflies of Oregon and find that the distribution of high-diversity areas, using the estimated, or “asymptotic”, diversities, is strikingly different from the geographic pattern one would deduce if the raw data were used, without correcting for differential sampling effort. Further, we show that differences in accuracy exist between the two estimation procedures, and that these differences are aggravated at small sample sizes; we argue that estimates based on the lognormal distribution should be preferred because they can offer substantial improvement over analyses based solely on the raw data, generally without risking overestimation. Lastly, using both the database and estimated values of butterfly diversity, we show that the distribution of endangered and numerically rare butterflies rarely coincides with “hotspots” or centers of biodiversity. Thus, protecting regions of Oregon rich in overall butterfly diversity will not normally protect the bulk of rare or endangered butterfly species.  相似文献   

运动的连续平直面上边界层流之解的渐近性质     

Sing.  BB Kumar  A. 《湖南农业大学学报(自然科学版)》1989,16(1)

Falkner-Skan方程描述磁场中连续平直面上不可压缩粘性流的边界层流,本文研究此方程初值问题之解的渐近性质。  相似文献