类具有急慢性阶段和垂直传染的非线性SACS传染病模型

研究一类具有非线性接触率和垂直传染且在急慢性阶段均传染的非线性SACS传染病侍播数学模型动力学性质,确定了各类平衡点存在的条件阈值,讨论了各平衡点的稳定性,并将会在临界值处出现Hopf分支,揭示了急慢性阶段传染对疾病发展趋势的共同影响.

Abstract：

The dynamics of a nonlinear SACS epidemic model with vertical transmission, which has infective force at both acute and chronic stages, is studied. The conditions and thresholds for the existence of various equilibria are established. The stability of equilibria is discussed, and periodic solutions may appear by Hopf bifurcation. The influence of infectivity at acute and chronic stages on the developing trend of the disease is disclosed.     

细胞内免疫滞后的病毒感染模型的稳定性和Hopf分支分析

在假设细胞内免疫反应有时间延迟的情况下对一个病毒感染模型的动力学形态进行了分析.研究了非负平衡点的稳定性和Hopf分支的存在性,并利用规范型和中心流形理论得出了分支方向、周期解的稳定性及周期的公式.

Abstract：

The dynamics of a viral infection model is analyzed under the assumption that the intracellular immune response is retarded. Stability of nonnegative equilibria and existence of Hopf bifurcation are studied. Using normal form theory and center manifold argument, we calculate the explicit formulas to determine the direction, stability and period of the bifurcating periodic solutions.     

具有竞争的Leslie型捕食者-食饵模型的定性分析

考虑了具有竞争的Leslie型模型.证明了解的最终有界性,和系统在一定条件下的一致持续生存性.研究了平衡点的局部稳定性.通过构建适当的Lyapunov函数,获得了正平衡点全局渐进稳定的充分条件.

Abstract：

In this paper, a competitive Leslie model is proposed. It is proved that the system's solution is ultimately bounded and the system is consistent and sustained under appropriate conditions. The local stability of the equilibria is investigated. By constructing a suitable Lyapunov functional, sufficient conditions are derived for the global stability of the positive equilibrium of the model.     

一个具有季节性的离散传染病模型的稳定性和Naimark-Sacker分支

分析了一个具有季节性种群生长和疾病传播的离散传染病模型.如果基础再生教0< R0 <1,非平凡的无病平衡点是全局稳定的,而当R0>1,模型存在唯一的正平衡点并且在适当的紊件下存在Naimark-Sackep分支.此外,如果分支点处的特征值的辅角是有理敷或无理数,则模型的解是周期的或拟周期的.

Abstract：

In this paper, we analyze a discrete epidemic model with seasonal population reproduction and disease transmission. If the basic reproduction number 0< R0 < 1, the nontrivial disease-free equilibrium is globally stable; if R0 > 1, there exists a unique positive equilibrium and the model undergoes a Naimark-Saeker bifurcation under suitable conditions; and if the argument of eigenvalue at the bifurcation point is rational or irrational, the solution of the model is periodic or quasiperiodic, respectively.     

一个比率依赖的Holling-Tanner捕食者-食饵模型的Hopf分支分析

分析了一个比率依赖的Holling-Tanner捕食者-食饵模型的全局性性态,证明了超临界Hopf分支的存在性.     

Selecting the Packaging System for Liquid Foods Using an ANP Model

This paper provides a model to identify the most appropriate packaging system （i.e. the industrial process by which the product is hygienically coupled with the container） for different liquid foods. The model developed is grounded on the Analytic Network Process （ANP） methodology, a powerful and flexible tool used in decision making. To select the appropriate packaging system, the model takes into account several factors, including packaging material, cost, safety, performance （e.g., speed and accuracy）, plant reliability and flexibility, which may directly or indirectly affect the suitability of the process. Moreover, the chemical and physical properties of commercial liquid foods, and the packaging technology are included in the model as further variables to be considered for the final choice. We try to answer the following research questions： is a filling system appropriate for a given liquid food？ Is it compatible with a defined packaging technology？ When several filling systems are available for a given liquid food, how can the most appropriate one be selected？ The ease of application of the model and the robustness of the results provided have been tested on a sample of 59 commercial liquid foods, for which the model allowed to identify the most suitable packaging system, providing useful practical guidelines. The model was developed in close collaboration with a panel of experts, operating in the beverage bottling industry, and validated by the same experts; thus, the resulting tool is suitable for use as a decision support system by food and bottling industries.     

基于度量的SPTO实施模型与方法

将软件度量与软件项目跟踪与监控活动联系在一起,提出了一个完整的基于度量的SPTO过程实施模型,围绕该过程模型研究了项目跟踪与监控的实施方法,使软件企业能够更高效的理解、控制和改进软件项目开发.

Abstract：

Software project tracking and oversight (SPTO) is an important component of the software process management, and the key of it is how to carry on the effective tracking and analysis of the project.This paper proposes a complete implementation model based on measurement: SPTO process model. Surrounding this model, we thoroughly study the implementation methods of SPTO.     

基于生长模型的林分场景可视化构建研究

林分场景的可视化构建,是基于林分的自身生长规律模型,通过计算机图形学的理论和虚拟现实的方法来实现的.以北京市昌平区油松人工林为研究对象,利用现有的森林资源调查数据,结合预测林分生长精度较高的胸高断面积模型,通过林分场景渲染的各种方法,实现了林分生长的可视化模拟.

Abstract：

Stand visualization is realized based on a stand growth model and performed by using computer graphics theory and virtual reality approach. In a study reported in this paper, stand growth simulation of a Chinese pine plantation in Changping District of Beijing was fulfilled, using the existing forest inventory data and combining it with a stand basal area growth model which has high prediction accuracy, according to a variety of scene rendering methods.     

基于Matlab的加密算法DES的设计与实现

给出了一种基于Matlab的带有图形用户界面(GUI)的DES程序的设计及实现过程.本程序可以用于实际的加密,更重要的是为DES的教学和实验提供了一个方便直观的工具.

Abstract：

.DES (Data Encryption Standard), which was the most widely used cryptosystem in the world, is still used as a model for teaching and research.This paper describes the design and implementation of a Matlab-based DES encryption algorithm.Our program with a comfortable GUI (graph user interface) can be used in practical encryption.What is more important is that it offers a convenient tool for DES teaching and experiments.     

Crop Insurance,Premium Subsidy and Agricultural Output

This paper studied the effects of crop insurance on agricultural output with an economic growth model. Based on Ramsey-Cass-Koopmans （RCK） model, a basic model of agriculture economic growth was developed. Extending the basic model to incorporate uncertainty and insurance mechanism, a risk model and a risk-insurance model were built to study the inlfuences of risk and crop insurance on agricultural output. Compared with the steady states of the three models, the following results are achieved：（i） agricultural output decreases if we introduce uncertainty into the risk-free model;（ii） crop insurance promotes agriculture economic growth if insurance mechanism is introduced into the risk model;（iii） premium subsidy constantly improves agricultural output. Our contribution is that we studied the effects of crop insurance and premium subsidy from the perspective of economic growth in a dynamic framework, and proved the output promotion of crop insurance theoretically.