Global analysis for an epidemical model of vector-borne plant viruses with disease resistance and nonlinear incidence

Vector-borne disease models play an important role in understanding the mechanism of plant disease transmission. In this paper, we study a vector-borne model with plant disease resistance, disease exposed period and nonlinear incidence. We compute the basic reproduction number, determine the implicit locations of equilibria and then investigate their global stability by generalizing a classic geometric approach to higher dimensional systems. Higher dimensions cause greater difficulties such as the construction of the transformation matrix and the estimate of the $Lozinski\tilde{\iota}$ measure in this geometric approach. For a complete control of vector-borne diseases, a quantitative way is provided by the given expression of the basic reproduction number, from which we need not only increasing plant disease resistance but also decreasing the contact rate between infected plants and susceptible vectors instead of a single one of them.     

基于改进灰色关联度的IOWA算子最优组合预测模型

通过引进诱导有序加权平均(IOWA)算子和改进灰色关联度的计算式,提出了新的基于改进灰色关联度的IOWA算子的组合预测模型.方法可以克服传统的组合预测方法赋予不变的加权平均系数和以单一误差指标作为预测精度衡量的缺陷.定义基于改进灰色关联度的IOWA算子的优性组合预测的概念,最后给出实例分析表明了新模型能有效地提高组合预测精度.     

Jordan isomorphisms of finitary incidence algebras

Let X be a partially ordered set, R a commutative 2-torsionfree unital ring and FI(X, R) the finitary incidence algebra of X over R. In this note we prove that each R-linear Jordan isomorphism of FI(X, R) onto an R-algebra A is the near-sum of a homomorphism and an anti-homomorphism.     

A class of Lyapunov functions and the global stability of some epidemic models with nonlinear incidence

In this paper, by investigating an SIR epidemic model with nonlinear incidence, we present a new technique for proving the global stability of the endemic equilibrium, which consists of introducing a variable transformation and constructing a more general Lyapunov function. For the model we obtain the following results. The disease-free equilibrium is globally stable in the feasible region as the basic reproduction number is less than or equal to unity, and the endemic equilibrium is globally stable in the feasible region as the basic reproduction number is greater than unity.The generality of the technique is illustrated by considering certain nonlinear incidences and SIS and SIRS epidemic models.     

斜入射激光等离子体堵口时空特性研究

 在“星光II”上首次利用X光12分幅相机(XFC)成功地观测到了1.053 μm激光以45°方向斜入射孔靶和半腔靶等离子体堵口的时间和二维空间图象，获得了等离子体堵口速度，同时通过一维模型给出了斜入射条件下的等离子体堵口速度。实验结果表明：相同参数条件下半腔靶与孔靶相比，等离子体喷射速度高约15%。一维模型给出的等离子体喷射速度与XFC测出的等离子体喷射速度在实验误差范围内是一致的。     

利用光栅测量任意入射角方式下的光波波长

以光栅衍射方程为理论依据，讨论了在任意入射角方式下，如何利用光栅和分光计对光波波长进行测量并同时能得到未知入射角的值。给出了理论推导和实验结果。结果表明：该方法的所得到的光波波长的相对误差为0．21％。     

基于理想关联度的不确定多属性决策方法

针对只有部分属性权重信息且属性值以区间数形式给出的不确定多属性决策问题,提出了一种逼近理想关联度的决策分析方法。首先改进了文[4]给出的区间数决策矩阵的规范化方法;然后提出了利用期望-方差区间数排序方法求解理想最优方案;最后依据关联系数矩阵给出了属性权重信息不完全的区间数多属性决策问题的求解方法,其核心是求解线型规划得到属性权重,进而根据各个方案与理想最优方案的综合关联度大小进行排序。特别地,给出了属性权重完全未知的简洁方法,文后的实例验证了方法的可行性和有效性。     

Optimal domain decomposition via -median methodology using ACO and hybrid ACGA

In this paper an efficient method is developed for decomposing large-scale finite element meshes. A weighted incidence graph is used to transform the connectivity properties of finite element models into those of graphs. A graph G_c of manageable size is obtained from the main graph model by a coarsening algorithm. The p-medians of this graph are selected using two approaches. The first algorithm uses an ant colony optimization and the second algorithm employs a hybrid ant colony together with genetic algorithm. Here, p is the number of subdomains which the finite element meshes is intended to be decomposed. Once the medians are obtained, the nodes in G_c associated with each median are selected. In an expansion process, the nodes of the subdomains in G are obtained. The capabilities of both ant colony optimization, and hybrid ant colony and genetic algorithm are evaluated using many examples of different topology.     

消像散掠入射平场光栅谱仪及其在等离子体XUV光谱诊断中的应用

研制成一台由柱面反射镜和球面反射镜组成的掠入射前置光学系统和变间距球面光栅组成的掠入射平场光栅谱仪,它不仅有较高的效率和光谱分辨,调整方便,而且还具有在4.4nm～30nm波长范围里同时获得一维空间分辨光谱的能力.用该谱仪成功地获得了线聚焦激光产生的Si,Cu及其它元素的等离子体柱的轴向空间分辨光谱.该谱仪很适合与具有平直接收表面的光电探测器,如软X射线条纹相机等联用以获得时间分辨光谱.