| The Northwest cities and towns are sensitive areas of ecological vulnerability in China,it is effective to explore the fluctuations and feedback mechanism between the development of the northwest urban and the fragile environment.There is a mutual nonlinear influence mechanism between the urban development of Wu-Chang-Wu Oasis and the fragile oasis environment,studying this association mechanism can understand the influence of the internal driving force of Wu-Chang-Wu towns system effectively.Taking Urumqi,Changji and Wujiaqu as examples,this paper uses RS/GIS technology to cover the area and extract it,And uses band calculations to classify the region’s ecological environment index from 2005 to 2015,simultaneously,gives an vulnerability assessment to the towns in combination with the city’s yearbook,The results show that: 1.The area of cultivated land in the Wuchang-5 area continued to decrease(3.27% in 10-15 years),the area of bare land decreased(37% dropped to 30%),the area of built-up area increased(5.38% rose to 9.42%),sand The area of land and saline land increased,and the area of forest land/grass increased.2.The overall environmental quality changes in the five districts of Wuchang and Wuchang show a tendency towards central distribution,that is,the evaluation of the inferiority and the excellent evaluation gradually decrease with time,and the moderate evaluation and good evaluation gradually increase.The evaluation of goodness increased from 16.8% to 31.4%,the moderate evaluation increased from 37.9% to 51.9%,and the evaluation of goodness dropped from 23.5% to 12.2%.3.The evolution characteristics of ecological and environmental vulnerability of Wuchang-5 from 2005 to 2015 are as follows: Decline in 2005-07,increase in 07-08,and decrease in 08-15.It shows that the local government has paid full attention to urban environmental work and has made outstanding achievements in the construction of the urban environment and facilities.This paper conducts a multivariate spacetime Markov fluctuation analysis of the highlevel system after discussing the fluctuation process of the original data to obtain the fluctuation process of each system during the period from 2005 to 2015,and the reasons behind the fluctuations in the data were found according to the report of the urban operation.At the same time,using the system dynamics Vensim software to simulate the urban development system and the oasis environmental fragility system,according to the simulated numerical analysis to observe the urban data changes,the nonlinear feedback mechanism of each subsystem between urban systems in the region was analyzed.It is proved that the relationship between different systems in cities and towns is not only a simple linear change,but a nonlinear feedback change that is influenced by many factors.In addition,the differences in the development and operation of cities and towns are given in the case where different influence factors are emphasized(ie,the government emphasizes the development of different factors).This paper describes the van der Pol equation and Lorentz equation in the brittle application of urban development process and gives the van der Pol equation to observe the chaotic characteristics of the urban system(limit cycle),studies its internal delivery mechanism,and shows that the point of bifurcation of the system is the brittle point of the urban system,this will provide effective suggestions for the smooth development of the Wu-Chang-Wu towns system. |
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