一类具有饱和传染率的时滞传染病模型的全局稳定性

研究了一类具有非线性饱和传染率和时滞效应的SEIR传染病模型,给出了用于判断疾病是否持续流行的基本再生数R_0.利用Lyapunov方法和LaSalle不变原理证明了当R_0≤1时,无病平衡点全局渐近稳定;当R_01时,疾病平衡点全局稳定.     

媒体报道下的一类SIS传染病模型的动力学行为研究

讨论了一类基于媒体报道下的SIS传染病模型的动力学行为.该模型存在两个平衡点即一个无病平衡点和一个地方病平衡点.给出了控制疾病持久与灭绝的临界值R_0,当R_01时,无病平衡点是全局渐近稳定的,意味着疾病是灭绝的;另一方面,当R_01时,地方病平衡点是全局渐近稳定的,也即疾病是持久的.最后通过数值算例对本文的结论进行了验证.     

一类迁移人群具有部分免疫的肺结核模型的分析

为预防肺结核疾病的传播,利用传染病建模思想,建立了一类迁移人群具有部分免疫的饱和发生率的肺结核模型.分析表明当移入潜伏者和染病者的比例均为0时模型才存在无病平衡点和基本再生数R_0.利用Lyapunov函数方法证明了当R_0≤1时,无病平衡点P~0是全局渐近稳定的;当R_00时,无病平衡点P~0是不稳定的.同时模型存在唯一的全局渐近稳定的地方病平衡点P~*.数值模拟结果与理论结果相一致,并使用模型对我国未来几年肺结核疫情进行了预测.     

具有潜伏期及非线性免疫反应的HTLV-I模型稳定性分析

建立具有潜伏期和非线性免疫反应的HTLV-I传染模型,研究模型的动力学性态,得到病毒感染再生数R_0和CTL免疫再生数R_1.通过构造Lyapunov函数证明:当R_0≤1时无病平衡点P_0是全局渐近稳定的;当R_01且R_1≤1时,无免疫平衡点P_1是全局渐近稳定的;当R_11时,正平衡点P_2是全局渐近稳定的.     

具有饱和发生率与混合控制策略的SEIQR模型的全局动力学（英文）

建立了一个具有饱和接触率和混合控制策略的SEIQR传染病模型,从理论和数值模拟方面分析了模型的稳定性.首先,得到了疾病灭绝与否的阈值——基本再生数R_0;其次,当R_01时,利用LaSalle不变集原理证明了无病平衡点是全局渐近稳定的,疾病最终消亡.当R_01时,根据Routh-Hurwitz判据定理证明了地方病平衡点局部渐近稳定;然后,当R_01时,运用周期轨道稳定性理论和第二加性复合矩阵证明了地方病平衡点全局渐近稳定,疾病持续存在;最后,利用计算机仿真,进一步证实理论分析的正确性.     

一类具有垂直传染的非线性发生率的SIS传染病模型的稳定性分析

讨论了一类具有垂直传染的非线性发生率的SIS传染病模型,得到了阈值R_0。并讨论了当R_0≤1时,无病平衡点是全局渐近稳定的,而当R_01时,地方病平衡点是全局渐近稳定的。     

一类具有高危人群及医院治疗的模型分析

建立了一类易感者分为高危人群和低危人群的传染病模型,运用下一代生成矩阵法得到了基本再生数R_0.应用Lyapunov函数证明了当R_01时,系统存在唯一无病平衡点P_0且全局渐近稳定,疾病最终消亡;当R_01时,系统存在唯一地方病平衡点,并且在该点处是全局渐近稳定的.通过数值模拟,验证了理论的正确性.     

潜伏类和移出类具有传染性的SEIR模型的渐近性分析

研究了一类潜伏类和移出类均具有传染力的SEIR传染病模型,得到了疾病流行与否的阈值:基本再生数R_0.运用Liapunov函数方法,证明了当R_01时,无病平衡点E_0全局渐近稳定,疾病最终消失;利用Hurwitz判据定理,证明了当R_01时,E_0不稳定,地方病平衡点E*局部渐近稳定;当因病死亡率和剔除率为零时,地方病平衡点E*全局渐近稳定,疾病持续存在.最后,进行了计算机数值模拟来进一步验证理论结果的正确性.     

一类多个平行传染阶段分数阶SEI传染病模型的Lyapunov函数

本文研究了一类分数阶SEI传染病模型的全局稳定性问题,得到了模型的无病平衡点Q~0与有病平衡点Q~*。通过构造相应的Lyapunov函数对平衡点的全局稳定性进行讨论,得到以下结论:当R_01时,模型只存在无病平衡点Q~0,无病平衡点Q~0是全局渐进稳定的;当R_01时,模型存在无病平衡点Q~0以及地方病平衡点Q~*,地方病平衡点Q~*是全局渐进稳定的。     

具有家庭干预的HIV/AIDS模型动力性研究（英文）

考虑一类具有移民、筛选和家庭干预的HIV/AIDS传染病模型的全局动力性.确定了模型的阈值R_0.当R_01,无病平衡点是全局渐近稳定的,疾病死亡;当R_01,唯一的地方病平衡点是全局渐近稳定的,疾病持续下去.同时也研究了模型平衡点的稳定性和敏感度行为.最后运用数字模拟来支持所得结果.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.