基于SEIR模型的新型冠状病毒肺炎疫情分析

对新型冠状病毒肺炎的传播规律进行研究,为传染病防控提供科学依据.基于每日发布的新冠肺炎确诊人数数据集,采用经典的SEIR(Susceptible-Exposed-Infected-Recovered)传染病动力学模型模拟疫情传播过程;利用最小二乘法对感染系数β和恢复系数γ进行参数估计;通过过滤原始数据集、优化感染人群初始值I0和恢复系数γ等方法进一步提高模型预测的准确率.该方法能够合理地预测疫情确诊人数和疫情拐点,对全国、湖北省确诊人数的预测误差率分别不超过2.04％、1.25％,对于疫情防控具有实用价值.     

基于时空特征的社交网络情绪传播分析与预测模型

社交网络用户情绪传播与用户的空间距离和时间跨度有关,并且受到多种交互机制的影响.从大规模社交网络数据中提取情绪传播的时空特征,研究用户行为对情绪传播的影响,对预测情绪传播趋势具有实际意义.利用线性回归获取的各行为子层的情绪传输率之间存在差异.提出一种基于多层社交网络的情绪传播模型,被称为ECM模型（Emotional contagion model）.该模型包括三个行为子层,每层的拓扑结构各不相同,由该行为的交互历史决定.在真实数据上对ECM模型进行仿真分析,可以获得社交网络中情绪传播的过程与规律:1）中性情绪用户所占比例随时间逐渐增大,接近57.1%,而正向情绪与负向情绪比例始终接近.2）情绪传输率越大,用户情绪更容易受到其他用户的影响而发生变化;初始情绪越中立的用户,在演化过程中情绪波动越小,而初始情绪极性越大的用户情绪波动越大.此外,通过实验对比该模型与其他情绪传播模型,表明ECM模型更加接近真实数据,对社交网络中情绪传播具有较好的预测效果,预测准确率相比其他模型可以提高1.8%~7.8%.     

网络视频传播过程的生存分析研究

根据互联网中正常视频与不良视频传播的有效活跃期及其影响因素,采用生存分析方法对视频传播过程进行分析。利用COX比例风险回归模型研究影响视频有效活跃期的影响因子。研究结果表明,不良视频的活跃时间比正常视频的活跃时间更长,视频内容对网络视频活跃有效期有一定影响。     

基于灰色Verhulst的互联网上网人数动态预测模型

在分析最近几年我国互联网上网人数实测数据的基础上,根据数据本身所具有的特征,引入灰色Verhulst预测理论,通过分析建立了我国互联网上网人数的灰色Verhulst动态模型,并通过所建立的模型对2000~2005年我国互联网上网人数进行实例验证和误差检验。检验结果表明,所建立的灰色Verhulst动态模型对实测数据具有很高预测精度,具有一定的研究和应用价值。     

基于多Agent和改进Deffaunt模型的信息传播建模与仿真

研究社会化营销中的信息传播对提出合理策略建议、提升企业竞争力有重要意义.信息传播是一个存在个体交互的复杂过程,多数信息传播模型中对现实情况做了较多的简化,没有考虑个体的异质属性对信息传播的影响,也无法体现个体间的交互,本文从复杂系统的角度研究信息传播过程,运用多Agent方法建立信息传播模型,并基于改进的Deffaunt模型建立多Agent交互机制,通过模拟仿真分析了不同因素对信息传播的影响,发现个体的异质属性、个体间的相互影响力以及外界环境的因素对信息传播的速度和范围均有一定的影响..     

一种软件项目人员流动风险定量评估模型

提出了一种评估软件项目人员流动风险的定量模型。该模型将关键人员占整体项目组成员人数的比例作为该模型的一项；流入、流出和更换关键人员数量分别占总关键人员数量的比例作为其他三项，并赋以后三项不同系数以区分其对项目的不同影响；同时考虑不同过程模型和处于模型中不同阶段使人员流动引起项目的风险程度也都不相同，又给以上三项赋以模型系数和阶段系数。模型中各系数通过公司的历史记录和专家评估获得。对该模型进行效果验证表明该模型科学合理、可以作为企业控制项目人员流动风险的依据。     

离散时间下混合型良性蠕虫的建模仿真分析

为了更好地刻画良性蠕虫的传播过程,采用了离散时间模型。在离散时间下,考虑恶性蠕虫和良性蠕虫传播对网络的影响,对混合型良性蠕虫的传播过程进行分析和数学建模,通过仿真验证传播模型,并引入泰勒公式对关键参数进行分析比较。理论分析和仿真实验表明,在混合型良性蠕虫释放时间和网络性能一定的条件下,存在一个临界值使得切换时间最佳,而网络敏感度足够小时,不同的切换时间对感染类主机数量的变化几乎没有影响。     

基于微博的事件传播分析

事件的传播分析是社交网络分析中一个重要的研究点.网络热点事件的爆发通过社交网络迅速传播,从而在短时间内造成很大的影响.而在社交网络中制造舆论热点进行传播的代价相对于传统媒介较低,因此很容易被不法分子利用,对社会安全以及人们财产造成损失.传统的影响传播分析仅能对单条博文进行影响传播分析,这使社交网络中的事件传播分析受到限制.在已有的独立级联模型的基础上,提出了一种结合用户去重、垃圾用户滤除和概率阅读的传播模型,其基本思想是对多条热点博文构成的事件进行用户去重,构建事件传播网络拓扑图,然后对其中的垃圾用户节点进行滤除,最后利用概率阅读模型进行影响传播分析.这为事件传播分析提供了思路.通过一系列实验来验证方法及模型,通过与传统的博文分析进行对比,验证了方法的正确性与有效性.     

一类考虑病毒发生变异的SIS疾病传播模型

为了研究变异行为对病毒传播的影响,提出了一个病毒发生变异的疾病传播模型,在模型中考虑了两种病毒相互转换的过程,计算机模拟结果表明,两种病毒的稳态感染比例与它们之间的相互转换概率γ1和γ2有关,当γ1＞0且γ2=0时,I1型感染者将消失,当γ1与γ2都大于0时,I1/I2与γ1/γ2成反比,且与α1/β1和α2/β2的取值无关.研究还发现病毒变异时由于缺乏对应的治疗药物和措施而出现一段真空期,这导致变异病毒的感染比例快速增加,但真空期的出现只能增加感染者的瞬时感染比例,而对稳态感染比例没有影响.该研究对人们深入理解病毒传播机理具有启发作用.     

一种基于网络熵的计算机网络攻击效果定量评估方法

本文通过假设,构建了攻击效果定量评估模型,围绕计算机受攻击后安全性的变动对网络熵值的影响进行了研究。在网络安全指标的选择方面进行了合理的简化,最终用分层分析方式对网络熵差进行一定的分析。在计算过后,得出了结论:通过模拟方式建立的模型是对网络攻击结果的真实体现。下文对该实验进行的具体过程进行了叙述,并完成了虚拟模型的构建及方程式的确立,旨在推动我国计算机网络事业的进一步发展,提升我国网络对抗综合实力。     

Activation of Immune Response in Disease Dynamics via Controlled Drug Scheduling

The human immunodeficiency virus (HIV) infection, that causes acquired immune deficiency syndrome (AIDS), is a dynamic process that can be modeled via differential equations. The primary goal of this paper is to introduce a control philosophy to boost the response of the immune system by means of drug scheduling. The control purpose is to steer the system to an equilibrium condition known as long-term nonprogressor, which corresponds to an infected patient that does not develop the symptoms of AIDS. The feasibility of the control methodology is illustrated via simulations on two HIV dynamic models and on a general disease model.     

A system theoretic study on a treatment of AIDS patient by achieving long-term non-progressor

There has been much recent interest in the long-term non-progressor (LTNP), who has been infected with human immunodeficiency virus (HIV) but does not proceed to AIDS. Under the assumption that a mathematical model describing the HIV infection and drug effects is true for real systems, we claim that it is possible to steer the state of any patients to that of LTNP if the model parameters belong to the proposed parameter intervals. Once the state is transferred close to LTNP, CTL memory is established and the viral load remains very low level even after the medication is stopped. In order to justify the claim, we first analyze the stability and the bifurcation of the model and show that there exists an equilibria curve towards LTNP, which is stable for all fixed constant inputs except some singular points. Then, we propose a new treatment strategy based on a useful property of Non-vanishing Basin of Attraction (NvBA)-stability. An extensive simulation study is also included to validate the proposed treatment for various initial conditions and to show the robustness against the parameter uncertainty. From a practical perspective, it deserves further investigation whether the proposed treatment strategy could switch a patient into LTNP in the real world.     

Contemplating public policy in HIV/AIDS online content,then where is the technology spirit?

Adaptive structuration theory (AST) has long been an accepted framework for investigating structures within technological artifacts and work environments. Information systems, organization science and communication scholars have prefaced AST context in terms of collaborative, group decision support systems. The social structures, however, can be characterized by features of rules, resources and capabilities along with a communicative spirit. Spirit is said to enable the user to better understand and interpret the meaning of a technology. Our research varies from the traditional focus of AST studies given that our context is not in single, for-profit organization with a common corporate mission or objective. Rather, we concentrate on the HIV/AIDS pandemic among Black women and the spirit communicated to this population by a principal government healthcare website. By interacting with a group of healthcare experts and practitioners during a 14-month period, we sought to understand the site's meaning and indications as its mission is to disseminate HIV/AIDS and other pertinent medical information. Further, our findings suggest that AST is a research framework that functions as a source for the notion of spirit. The (un)intended spirit inscribed on information and communication technologies (ICT) may be (ex)inclusive with regard to the population or society it intends to serve. Hence, grassroots approaches and audiences can, in fact, offer effective insight into user-centered designs focused on educational and prevention content among those most affected and infected by chronic diseases, such as HIV.     

A cellular automata model considering diversity associated with HIV infection

The diversity of human immunodeficiency virus (HIV) in vivo has been reported. In this article, we propose a cellular automata (CA) model describing the interactions between the immune system and HIV, and examine the effect of the diversity of these interactions. The novel aspects of our CA model are that it not only considers four states (HIV, virgin, dead, infect) but also the diversity exhibited by both HIV and T cells. We simulated maximum diversities for these states by simulating CA on a computer. The model revealed that increased diversity had the effect of increasing the HIV population and simulation steps. In addition, we observed that the CA model accurately reflects the occurrence of infection, incubation period, and the development of AIDS. The CA model demonstrated that the diversity of the virus is the major factor affecting the success rate of the escape of HIV from the immune response. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

传染病在多层星型耦合网络上的资源控制

针对已有传染病传播模型没有考虑到具体的特殊网络结构与资源因素对控制疫情爆发的影响与作用机制,结合双层星型耦合网络与传染病SIS模型,建立了一个离散动态传播模型。该模型利用星型网络的结构特性与平均度概念推导各层感染人口比例关于资源及各种参数的离散方程。理论分析和仿真实验结果表明,多层星型耦合传染病传播网络中存在资源阈值,当节点为叶子节点时,网络存在两个资源阈值,增加资源量投入以抑制传染病传播只在两个资源阈值间有效,此时传染病感染人口比例随着投入资源的增加而减少;当节点为中心节点时,网络中的资源阈值随其他层感染人口比例的增大由两个减少至一个。此外,层间中心节点耦合强度、层间叶子节点耦合强度对疫情的控制效果随着节点所处位置的不同而不同。     

Estimation of HIV/AIDS parameters

This paper shows how well-established control system techniques can be introduced to formulate guidelines for clinical testing and monitoring of HIV/AIDS disease and the estimation of HIV/AIDS parameters. It is assumed that the viral load and healthy CD4+T cell in plasma are measured. The objective is to estimate all parameters in the basic three-dimensional HIV/AIDS model. For this purpose, through an analysis of basic system properties, the minimal number of measurement samples for the CD4+T cell and the viral load counts is first obtained. The paper determines then the HIV progression stages when an estimation of all parameters is impossible. Outside these stages, the paper proposes two on-line estimation algorithms for all HIV parameters based on the well-known techniques of adaptive identifiers and adaptive observers. Conditions for parameter convergence are discussed. Simulation results are demonstrated for the parameter estimation using adaptive observers.     

Mathematical model of HIV-infection transmission and dynamics in the size of risk groups

The research is aimed at developing and studying the distribution model of the human immunity deficit virus (HIV) that includes dynamics in the formation of risk groups. Most of the HIV distribution models assume that the risk of infection does not change over the individual’s lifetime. This work, in contrast, proposes a model of virus transmission in a population with a dynamic risk. The risk dynamics are described by the model of the formation of groups of individuals with alcohol and drug dependence, which are the main factors influencing the spread of HIV in Russia.     

Empirical Bayesian analysis of the Poisson intervention and incidence parameters

In some population the AIDS/HIV incidence rate θ∈(0,∞) is altered in the middle of a data collection period due to preventive treatments imposed by the health service agencies. The intervened Poisson (IP) model in [Comput. Programs Biomed. 17 (1983) 89; Biometrics 48 (1985) 559] was introduced which is appropriate to analyze data of this type. However, the classical approach leading to the maximum likelihood (ML), moment (M) or minimum variance unbiased (MVU) estimator of θ is mathematically formidable and practically inconvenient as far as sequentially updating the estimate when new data arrive. Previous subjective Bayesian work has been done to overcome these issues. Hence, there is a need to devise a more practical empirical Bayesian technique to estimate θ, and it is done in this article. The results are illustrated using a data on AIDS/HIV incidence in the state of Alabama. Advantages in the Bayesian intervened approach are cited.     

Empowering processes in online support groups among people living with HIV/AIDS: A comparative analysis of ‘lurkers’ and ‘posters’

The proliferation of online support groups provides an opportunity for individuals living with HIV/AIDS to obtain support online. The present study aimed to explore how different levels of participation in online support groups are associated with empowering processes and outcomes for individuals living with HIV/AIDS. A total of 340 individuals living with HIV/AIDS were recruited. They completed an online questionnaire consisting of measures on satisfaction with online support groups, empowering processes, self-care self efficacy, loneliness, optimism, coping, depression, and health-related quality of life. Results revealed that compared to posters, members who only read the messages (lurkers) scored lower in receiving social support and receiving useful information in empowering processes, and lower in satisfaction with their relationship with group members. They also scored higher in distraction and lower in planning in the brief COPE. In addition, they scored lower in social function and higher in energy. There were no significant differences in self-care self efficacy, loneliness, depression, or optimism between posters and lurkers. Our results suggest that lurking in the online support groups may be as empowering as reading and posting messages to the groups. More research is needed to identify the long term effects of online support group use.     

A schematic age-structured compartment model of the impact of antiretroviral therapy on HIV incidence and prevalence

A simple deterministic model is proposed to represent the basic aspects concerning the effects of different antiretroviral treatment schedules on HIV incidence and prevalence of affected populations. The model mimics current treatment guidelines applied in Brazil. However, the model does not intend to fit the data with any acceptable degree of accuracy since uncertainties on the values of the parameters and on the precise effect of the treatment put some limits on the practical implications of our model from which only orders of magnitude and some qualitative effects can be deduced. So, this paper intends to provide a conceptual and mechanistic understanding of the possible long-term effects of treatment on the dynamics of HIV transmission.According to the model, the effect of the treatment depends on the level of sexual activity of the subpopulations considered, being more pronounced on the subpopulations with the highest sexual activity levels. Also, inefficient treatment can be prejudicial depending on the level of sexual activity and on the capacity to provide adequate treatment coverages to the population affected.