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An SIR epidemic model with incubation time and saturated incidence rate is formulated, where the susceptibles are assumed to satisfy the logistic equation and the incidence term is of saturated form with the infective. Threshold quantity R0 is derived which determines whether the disease dies out or remains endemic. If R0 <; 1, the disease-free equilibrium is globally asymptotically stable and...
The information of pixels in plantlets in vitro was acquired using image analysis technique. Several flasks of plantlets, which biomass were known through the contact weighing, were used for internal references, and the models of biomass vs. pixels were fitted. The biomasses of plantlets to be determined were estimated based on the models. The logistic equations were used for the fitting of biomass...
Atractylodes lancea (thunb.) DC is a kind of geoherbs. The superior variety by the selecting of the A. lancea is vital to promoting production. In the present study, we had established the growth model for stem thickening, plant height increment and leaf area expansion using the logistic equation with four parameters. The growth parameters of four type's A. lancea were compared. The prediction on...
Water Contaminations bring not only great damage to the ecological balance, but also serious losses to the national economy. The results of existing methods, which are used to calculate Economic Loss of water contaminations, are not able to reflect the problem explicitly. In view of deficiencies of those calculation methods, and on the base of mechanism model of pollution loss, the logistic equation...
The mathematical model of population growth is based on logistic equation and BP neural network. The total population is predicted for the next 30 years through the use of Logistic modeling and generalization data. The dynamics of population growth is studied in non-linear dynamic, which pointed out that the problem is the issue of chaos. It is difficult to accurately forecast long-term population...
As the development of bionics, there are more and more ecological theories and methods applied to the research of economics. The virtual enterprise cluster is a special kind of dynamic alliance in the cyber-society. Through the course of clustering, the enterprises can reduce the cost of production and transaction; form a stable and solid relationship of professional production and cooperation, and...
Symbiotic Virtual Enterprise Cluster (SVEC) is a dynamic alliance, and there is a relative balance between enterprises. Some similarities are exhibited between species in nature and SVEC, such as ecological balance and evolution. In this paper, logistic equation, from biology, is borrowed to construct Ecological balance Model, conditions for SVEC to reach its ecological balance and the optimal solutions...
Logistics and economy influence each other, and their relationship is dynamically changeable. The economy of different stages exhibits various demand for logistics. In order to explore the evolution law of the relationship between logistics and economy, this paper establishes an index system, a comprehensive comparison platform and an evolution model by the methods of principal component analysis...
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