一类SEIV模型的研究(英文)

本文主要研究一类带有饱和感染率且潜伏期也具有传染性的SEIV模型.运用微分方程中的极限理论和Busenberg-Driessche定理,建立了该模型的全局动力学性质;并且证明了当基本再生数R0≤1时,无病平衡点Q0是全局稳定的,当基本再生数R01时,疾病持续.     

基于仿真实验的休假Geom/G/1排队的性能分析

基于Matlab程序研究了带启动期的多重休假Geom/G/1排队系统,统计出系统的平均队长、顾客的平均等待时间及系统的状态概率等性能指标随系统参数的变化趋势,并与理论分析结果进行有效的对比.从而验证了已知文献理论分析结果的正确性.     

基于二层信用策略的两货栈库存模型

假设供应商向零售商提供信用支付期的同时,零售商也向顾客提供信用支付期,研究了两货栈的变质物品库存模型,并讨论了模型最优解的唯一性,最后给出了最优订购策略的算法步骤与数值例子.     

基于群智能算法的预防性维修周期优化

分析将蚁群优化算法应用于预防性维修周期工程寻优问题时遇到的算法参数选择困难等问题,提出将粒子群优化算法和空间划分方法引入该过程以改进原蚁群算法的寻优规则和历程.建立混合粒子群和蚁群算法的群智能优化策略:PS_ACO(Particle Swarm and Ant Colony Optimization),并将其应用于混联系统预防性维修周期优化过程中,以解决由于蚁群算法中参数选择不当和随机产生维修周期解值带来的求解精度差、寻优效率低等问题.算法的寻优结果对比分析表明:该PS_ACO算法应用于预防性维修周期优化问题,在寻优效率及寻优精度上有部分改进,且可相对削弱算法参数选择对优化结果的影响.     

A New Criterion on k-Normal Elements over Finite Fields

The notion of normal elements for finite fields extension was generalized as k-normal elements by Huczynska et al.(2013). Several methods to construct k-normal elements were presented by Alizadah et al.(2016) and Huczynska et al.(2013), and the criteria on k-normal elements were given by Alizadah et al.(2016) and Antonio et al.(2018). In the paper by Huczynska, S., Mullen, G., Panario, D. and Thomson, D.(2013), the number of k-normal elements for a fixed finite field extension was calculated and...     

基于成本效益分析的救护车多时段布局优化研究

院前急救服务水平和救护资源之间存在悖反效益,本文综合考虑急救服务效果与急救网络成本,应用延误成本刻画急救效果,运营成本刻画急救资源使用,同时考虑需求规模、需求空间分布、救护车行驶速度以及救护车不可获得率随时间变化的影响,建立以最小化社会总成本为目标的救护车多时段布局优化模型,应用上海市松江区的实际数据,系统研究多时段救护车布局优化问题。计算结果表明优化后的系统在保证80%的高标准覆盖水平下,社会总成本比原系统下降32.23%。相比静态的情况,考虑时变因素可以使社会总成本下降15.8%,双覆盖率提高12.84%,各时段车辆繁忙率方差下降91.67%。     

一类存贮模型及其最优存贮策略

当工厂仓库容量有限时,常常需要租借仓库来进行存贮.但是,由于租借仓库的存贮单价通常比自己仓库的存贮单价高,所以不能用经典的经济批量公式来计算,有必要重新进行研究.本文研究了原料仓库和产品仓库容量均有限条件下的定料生产销售存贮问题,建立了相应的存贮模型,给出了最优定料生产存贮策略.     

求分块三对角矩阵和分块周期三对角矩阵逆矩阵的快速算法

给出了分块三对角矩阵逆矩阵的快速算法,并利用所给算法得到了求分块周期三对角矩阵逆矩阵的快速算法.最后通过算例表示算法的有效性.     

On M/G/1 system under NT policies with breakdowns,startup and closedown

This paper studies the vacation policies of an M/G/1 queueing system with server breakdowns, startup and closedown times, in which the length of the vacation period is controlled either by the number of arrivals during the vacation period, or by a timer. After all the customers are served in the queue exhaustively, the server is shutdown (deactivates) by a closedown time. At the end of the shutdown time, the server immediately takes a vacation and operates two different policies: (i) The server reactivates as soon as the number of arrivals in the queue reaches to a predetermined threshold N or the waiting time of the leading customer reaches T units; and (ii) The server reactivates as soon as the number of arrivals in the queue reaches to a predetermined threshold N or T time units have elapsed since the end of the closedown time. If the timer expires or the number of arrivals exceeds the threshold N, then the server reactivates and requires a startup time before providing the service until the system is empty. If some customers arrive during this closedown time, the service is immediately started without leaving for a vacation and without a startup time. We analyze the system characteristics for each scheme.     

STABILITY OF AN SEIS EPIDEMIC MODEL WITH CONSTANT RECRUITMENT AND A VARYING TOTAL POPULATION SIZE

This paper considers an SEIS epidemic model with infectious force in the latent period and a general population-size dependent contact rate. A threshold parameter R is identified. If R≤1, the disease-free equilibrium O is globally stable. If R〉1, there is a unique endemic equilibrium and O is unstable. For two important special cases of bilinear and standard incidence ,sufficient conditions for the global stability of this endemic equilibrium are given. The same qualitative results are obtained provided the threshold is more than unity for the corresponding SEIS model with no infectious force in the latent period. Some existing results are extended and improved.