The present article is an analysis of the innovation system dynamics of the shrimp farming industry in Northeastern Brazil along with the forms of interaction and exchange of information and know-how and the generatio...The present article is an analysis of the innovation system dynamics of the shrimp farming industry in Northeastern Brazil along with the forms of interaction and exchange of information and know-how and the generation and diffusion of innovation characterizing its development. Brazil is the world＇s tenth-largest shrimp producer, with farms strongly concentrated in the Northeastern part of the country. Our findings show that the shrimp production/innovation system in Northeastern Brazil is highly institutionalized and is regulated, controlled and inspected by government agencies. In addition, the sector is now strongly networked with public universities, training and research institutions and other entities with varying degrees of autonomy and different forms of cooperation and integration. Parts of the technological innovations adopted by large companies in the sector are a spin-off of activities at universities and research centers. However, the close cooperation between public research/teaching institutions and large-scale producers is rarely extended to small and midsize businesses, whose interrelations become very fragile. The lack of communication between small producers and public research/teaching institutions makes it more difficult for farmers to assimilate new processes and to generate and incorporate innovations, compromising the dynamics of the production/innovation system of the shrimp farming industry in Northeastern Brazil.展开更多
The existence conditions of Hopf bifurcation for a predator prey model based on nutri- tion kinetics are given. The two results may appear as follows： one is that the model has a stable periodic trajectory from Hopf ...The existence conditions of Hopf bifurcation for a predator prey model based on nutri- tion kinetics are given. The two results may appear as follows： one is that the model has a stable periodic trajectory from Hopf bifurcation, which shows the system is in an eco- logical balance; the other is that periodic trajectory from Hopf bifurcation is unstable, which indicates the system is in a sharp or catastrophic loss of stability. For the latter, a bifurcation controller is designed to make the periodic trajectory stable. Finally, some simulations are carried out to prove the results.展开更多
文摘The present article is an analysis of the innovation system dynamics of the shrimp farming industry in Northeastern Brazil along with the forms of interaction and exchange of information and know-how and the generation and diffusion of innovation characterizing its development. Brazil is the world＇s tenth-largest shrimp producer, with farms strongly concentrated in the Northeastern part of the country. Our findings show that the shrimp production/innovation system in Northeastern Brazil is highly institutionalized and is regulated, controlled and inspected by government agencies. In addition, the sector is now strongly networked with public universities, training and research institutions and other entities with varying degrees of autonomy and different forms of cooperation and integration. Parts of the technological innovations adopted by large companies in the sector are a spin-off of activities at universities and research centers. However, the close cooperation between public research/teaching institutions and large-scale producers is rarely extended to small and midsize businesses, whose interrelations become very fragile. The lack of communication between small producers and public research/teaching institutions makes it more difficult for farmers to assimilate new processes and to generate and incorporate innovations, compromising the dynamics of the production/innovation system of the shrimp farming industry in Northeastern Brazil.
基金Acknowledgments This work was supported by the Science Foundation of Liaoning Province （20092179） and by the National Natural Science Foundation （60974004/F030101）.
文摘The existence conditions of Hopf bifurcation for a predator prey model based on nutri- tion kinetics are given. The two results may appear as follows： one is that the model has a stable periodic trajectory from Hopf bifurcation, which shows the system is in an eco- logical balance; the other is that periodic trajectory from Hopf bifurcation is unstable, which indicates the system is in a sharp or catastrophic loss of stability. For the latter, a bifurcation controller is designed to make the periodic trajectory stable. Finally, some simulations are carried out to prove the results.
