This paper studied a kind of BVP of nonlinear third order singularly perturbed equations by boundary layer function method. When gy′>0, at first, the problem was turned to a BVP of equivalent Tikhonov system. Then the asymptotic solution of doubly boundary layer for the system was constructed, and the character of exponential decay for all boundary functions was proved. Finally the main results of this paper: existence and uniqueness of solution and estimation of remainder for the problem are given. When gy′<0, in general, there is no solution to this problem.
This paper studied a kind of nonlinear stochastic difference equations, whose randomness is driven by a stochastic series. Two comparison theorems were obtained. At last, p-moment stability and p-moment boundedness of solutions to stochastic difference equations were presented as applications of obtained comparison theorems.
Using the tools of distinct excluded blocks, computational search and symbolic dynamics, the complexity of the times series generated by elementary cellular automaton of Rule 7 was analyzed, the set of distinct excluded blocks and its Chomsky hierarchy and the Chomsky hierarchy of a reduction of the evolution language were determined.Finally,the mathematical structure underlying the time series was obtained.
According to the characteristics of the language used in address, rules different from those of natural languages were defined and applied to automatically recognize and translate English address on postal mails. To deal with the address got from Optical Character Recognition, an English-to-Chinese address translation method based on inexact string matching technology was proposed to recognize English address and translate it into Chinese. The experimental results showed that the present method is capable of reducing the influence of OCR error, and improving the translation performance.
An effective ray tracing method based on virtual source tree for prediction of indoor radio propagation was presented in this paper. The data of transmiting source, reflection source, diffraction source and receiving point were stored with many-fork tree in Delphi, and the validity of the nodes of the tree was estimated, to make the ray tracing course more simple and efficient. It was found that the predicted results with the method are in good agreement with the simulated results in FDTD, and the validity of the method is also verified by the experimental test.
A clear presentation of the formulas and parameters in the Judd-Ofelt theory was given. Three intensity parameters was calculuted by the least-squares fitting method. Consequently, the algorithms of calculating the Judd-Ofelt parameters such as the oscillator strength, the spontaneous emission probability, branching ratio and radiative lifetime were discussed. Especially, three tables were given to make the complex algorithms be easily understood.
Co-based（Co69.20Fe4.16 Si12.35B10.77 Cr3.42 Mo0.1） amorphous microwires with 40 μm in diameter and 5 cm in length，were annealed by Joule current and by stress Joule annealing. The relationship between giant magneto-impedance effect and the density of annealing current and the intensity of stress was investigated. The results showde that the GMI ratios firstly increase then decrease with the increase of the density of current and the intensity of the stress. The maximum of sensitivity of GMI ratios to applied field is 1%/( A·m-1) at 20 A/mm2 and 90 MPa.The sensitivity of wires which were annealed with these conditions can be 19%/(A·m-1).
Moving boundary-layer simulation in the crash safety analysis is one of the most important projects in mathematical modeling.The research on the theory and application for the complex non-Newtonian properties in various testing conditions have been interesting and difficult problems especially in the auto-crash safety engineering process.In this paper an application of boundary-layer computing for the non-Newtonian rate type impact hardening and shear thinning problems.The accurate mathematical prediction would supply ultimate research tool for the passive safety analysis in such scale.The posteriori estimate combined with HPC 2D/3D modeling technique would supply effective methods in the research.
Based on the idea of balanced loss function, a new measuring standard for the estimations of uperiorities was proposed for general linear models. Under the new standard, the balanced generalized LS estimation of the regressive coefficient was derived. The necessary and sufficient condition for its unbiasedness was discussed and its superiority over BLUE in terms of the mean square error matrix criterion was studied.
Using transformation of coordinates of M.Vishik and L.Lyusternik, the method of boundary function was used to construct the uniformly valid asymptotic solutions of the Dirichlet problem of semi-linear singular perturbation elliptic equations.Under the uniformly valid asymptotic solutions obtained,the upper and lower solutions were constructed which satisfied the condition of Amann and guranteed the existence of the solution.Finally,the reminder estimation was made.
Experiments on sediment mixing characteristics under waves were carried out by using of a wave-flow-sediment flume. From experimental data, the vertical distributions of suspended sediment concentration (SSC) and vertical sediment mixing coefficients were determined under regular and irregular waves, respectively. It is found from experimental results that the vertical distribution of SSC agrees well with natural logarithm and the vertical sediment mixing coefficient may be described as εy=C1eD1Y.
Based on the Environmental Fluid Dynamic Code (EFDC), a 3-D water temperature and salinity model for the Changjiang Estuary and its adjacent areas was established. River discharge, tide, wind and solar radiation were considered in this model. Compared with the observed data in July 2005, the simulated results were fairly consistent with the observations. It can be analyzed from the results that the temperature isolines off the Changjiang Estuary in summer are along the south-north direction, with high values nearshore and low values offshore; in the Changjiang Estuary, the temperature is descending from the estuary to the offshore along the direction of Changjiang Diluted Water (CDW). The characteristics of CDW are prominent in summer. The low-salinity surface water can reach out 123° E and has a trend of east expansion off the Changjiang Estuary. The intensities of themocline and halocline are extremely high at the area of CDW, which reach the values of 0.3 ℃/m and 2/m, respectively. The positions of thermocline and halocline are coincident or close-by off the Changjiang Estuary.
Based on the distribution data of 22 dominant species of typical evergreen broadleaf forest of Castanopsis, Cyclobalanopsis and Lithocarpus (Fagaceae) and 11 climatic factors, the range types of these species and their relationship with environmental factors were analyzed by Correspond Analysis (CA) and Canonical Correspond Analysis (CCA). According to the result of CA, all could be roughly classified into two range types: east type and west type. The east type could be divided into two subtypes: south and north one. In accordance with the classification of species, the study region was also divided into three range regions: west region, northern east region and southern east region. According to the result of CCA, the major environmental factors of various spatial gradients were different. In east-west direction, the seasonality in temperature, mean temperature of the coldest month, sunshine duration, total actual solar radiation and aridity index had more effects on species distribution; while in south-north direction, the mean temperature of the coldest month and total potential solar radiation were the main limitations of the range of plants and played an important role on the northern boundary of species’ range region. Compared with other scheme of vegetation zonation of subtropical evergreen broadleaf forest zone, the boundary between eastern and western region of this paper was similar while the boundary between southern and northern region was north-leaned slightly.
中国综合性科技类核心期刊(北大核心)
