Qualitative Simulation Research On Biological Virus Complex System

The researches in the field Artificial Life are rising, which is a new discipline at the intersection of life sciences and computer science. The researching object is the life science, and the main researching content is the mechanism of life process and the information reasoning, simulation and implement, so it will play an increasingly important role in the both field of life science and information science.The method of computer simulation is the one of the core approaches used in the Artificial Life. Because of its virtue to be economical, credible, safe, flexible and can be used time after time, The technology of simulation was rapidly developed in recent years, and it is becoming an indispensable technology to analyze, design, test and evaluate a complex system.Unfortunately, the traditional quantitative simulation will be difficult when facing a complex system with the features to be fuzzy, stochastic and incomplete, and to address these problems, qualitative simulation was introduced to analyze these complex system. Compared to the traditional quantitative simulation, the qualitative one strived to model the problems with qualitative reasoning process like human beings. The introduction of induction reasoning, causal reasoning and graphic representation made the reasoning process and result easier to be understood, which extend the application fields of simulation technology.Based on the knowledge of Artificial Life, this dissertation aims to research the complex biological system like virus infection and epidemic, by using intelligent information technology especially qualitative simulation theory.To understand the qualitative theory, the motivation, academic structure and the application of the QR is given firstly. The possible researching direction is presented, and the method of cellular automata is introduced with its application field. Several theory problems in QSIM are discussed, including the computing of quantity space in QSIM, adding some new restriction to reduce the illogicality; the error of qualitative space when the variables appear more than once; using a random value to be the mark of qualitative symbol, and the qualitative addition and multiplication are given. A qualitative description method is proposed without hypothesis, and the qualitative behaviors of the system are given by describing qualitative states and the transitions between these states. The algorithm of building qualitative states is presented and then the qualitative states graph can be created from the dynamic model of viral infection. The reasoning algorithm is given to accomplish the transitions between the qualitative states. The qualitative simulation of the system is also given without precise formulation of the model.An epidemic spread model is built by considering the difference of infective ability and the resisting ability, the dynamic behavior of the infected hosts is shown with different immune parameters. The HIV infection process is also modeled based on cellular automata. The infective process is looked as spreading from the infective cells to susceptible ones. The states of cells are considered and the updating rules are given. The influence of infective parameter on the virus infection is discussed, and the complexity of infect velocity is analyzed with comparing to other methods.The qualitative technology is introduced to model and analyze the process of virus entry. A rough model is proposed first to be the foundation of further research. The factors are described qualitatively in influencing degree, and the qualitative model is built based on the interaction among these influencing factors and the viruses and cells. The judging matrices are constructed according to the qualitative model and the coherence of these matrices is verified.Using qualitative methods, we considered the interaction between virus and cell during the course of virus' entry, and modeled the whole process with system dynamic feedback analysis. Through the analysis of the interaction among virus, cells and environment, the consistency between qualitative predictive matrix and the quantitative one of the system is also given.Based on the qualitative process theory, the chemistry reaction with enzyme is modeled and analyzed qualitatively. The method with multi-view is used to model the enzyme promoting reaction and decompose reaction. The individual views in the process are given, and the main process views are added to the qualitative model. The qualitative states and the transition graph of the model are given finally.