This paper investigates the hydrological interactions in the atmosphere-evegetation-soil system by using the bucket model and several new simplified intermediately complex models. The results of mathematical analysis ...This paper investigates the hydrological interactions in the atmosphere-evegetation-soil system by using the bucket model and several new simplified intermediately complex models. The results of mathematical analysis and numerical simulations show that these models, despite their simplicity, can very clearly reveal the essential features of the rather complex hydrological system of atmosphere-ecosystem-soil. For given atmospheric variables, these models clearly demonstrate multiple timescales, the ＂red shift＂ of response spectra, multi-equilibria and limit cycles, bifurcation, abrupt change, self-organization, recovery, ＂desertification＂, and chaos. Most of these agree with observations. Especially, the weakening of ＂shading effect＂ of living canopy and the wilted biomass might be a major mechanism leading to the desertification in a relatively short period due to overgrazing, and the desertification in a relatively long period or in climate of change might be due to both Charney＇s mechanism and the shading effect. These ideas could be validated with further numerical simulations. In the paper, some methods for improving the estimation of timescales in the soil water evolution responding to the forcing are also proposed.展开更多
设计并搭建了制冷量为3 k W、以R124-DMAC为工质、采用电热高温空气模拟发动机排气废热的空冷鼓泡吸收制冷实验系统,通过改变热空气进口温度、冷冻水温度和浓溶泵流率测试系统工作参数的变化趋势。实验结果表明,当发生器稀溶液出口温度...设计并搭建了制冷量为3 k W、以R124-DMAC为工质、采用电热高温空气模拟发动机排气废热的空冷鼓泡吸收制冷实验系统,通过改变热空气进口温度、冷冻水温度和浓溶泵流率测试系统工作参数的变化趋势。实验结果表明,当发生器稀溶液出口温度约为100℃时,蒸发温度为-4℃,系统COP值最大可达到约0.54,而且实验系统稳定性较好;影响系统制冷量和COP值的主要参数是热空气进口温度和冷冻水温度;当蒸发温度低于5℃时,为了提高制冷效果需考虑设置精馏装置。展开更多
A novel 5-dimensional（5D） memristive chaotic system is proposed, in which multi-scroll hidden attractors and multiwing hidden attractors can be observed on different phase planes. The dynamical system has multiple l...A novel 5-dimensional（5D） memristive chaotic system is proposed, in which multi-scroll hidden attractors and multiwing hidden attractors can be observed on different phase planes. The dynamical system has multiple lines of equilibria or no equilibrium when the system parameters are appropriately selected, and the multi-scroll hidden attractors and multi-wing hidden attractors have nothing to do with the system equilibria. Particularly, the numbers of multi-scroll hidden attractors and multi-wing hidden attractors are sensitive to the transient simulation time and the initial values. Dynamical properties of the system, such as phase plane, time series, frequency spectra, Lyapunov exponent, and Poincar′e map, are studied in detail. In addition, a state feedback controller is designed to select multiple hidden attractors within a long enough simulation time. Finally, an electronic circuit is realized in Pspice, and the experimental results are in agreement with the numerical ones.展开更多
Using a coupled ocean-atmosphere model simplified, and the low spectrummethod and the equilibria theory, we discussed the interaction of South Asian winter and summermonsoons with sea surface tempera-ture(SST) seasona...Using a coupled ocean-atmosphere model simplified, and the low spectrummethod and the equilibria theory, we discussed the interaction of South Asian winter and summermonsoons with sea surface tempera-ture(SST) seasonal variation in the neighbor sea area. The resultsindicate that, when the winter monsoon is strong, the winter SST is low, and the SST will also below next summer; and vice versa. When the summer monsoon is strong, the summer SST is high; and viceversa. It is inconspicuous for SST in winter that summer monsoon is strong or weak.Ocean-atmosphere interaction reinforces winter and summer monsoons, while meridional SST gradientreinforces winter monsoon and weakens summer monsoon.展开更多
基金This work was supported by the China National Science foundation （Grant No, 40233027） N0AA 0ffice of Global Programs, NASA （NAGA-13322）+1 种基金the U. S. National Science foundation （ATM 0301188） the Chinese Academy of Sciences＇ 0verseas Assessor＇s Grant and Well-Known 0verseas Chinese Scholar Grant.
文摘This paper investigates the hydrological interactions in the atmosphere-evegetation-soil system by using the bucket model and several new simplified intermediately complex models. The results of mathematical analysis and numerical simulations show that these models, despite their simplicity, can very clearly reveal the essential features of the rather complex hydrological system of atmosphere-ecosystem-soil. For given atmospheric variables, these models clearly demonstrate multiple timescales, the ＂red shift＂ of response spectra, multi-equilibria and limit cycles, bifurcation, abrupt change, self-organization, recovery, ＂desertification＂, and chaos. Most of these agree with observations. Especially, the weakening of ＂shading effect＂ of living canopy and the wilted biomass might be a major mechanism leading to the desertification in a relatively short period due to overgrazing, and the desertification in a relatively long period or in climate of change might be due to both Charney＇s mechanism and the shading effect. These ideas could be validated with further numerical simulations. In the paper, some methods for improving the estimation of timescales in the soil water evolution responding to the forcing are also proposed.
文摘设计并搭建了制冷量为3 k W、以R124-DMAC为工质、采用电热高温空气模拟发动机排气废热的空冷鼓泡吸收制冷实验系统,通过改变热空气进口温度、冷冻水温度和浓溶泵流率测试系统工作参数的变化趋势。实验结果表明,当发生器稀溶液出口温度约为100℃时,蒸发温度为-4℃,系统COP值最大可达到约0.54,而且实验系统稳定性较好;影响系统制冷量和COP值的主要参数是热空气进口温度和冷冻水温度;当蒸发温度低于5℃时,为了提高制冷效果需考虑设置精馏装置。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51177117 and 51307130)
文摘A novel 5-dimensional（5D） memristive chaotic system is proposed, in which multi-scroll hidden attractors and multiwing hidden attractors can be observed on different phase planes. The dynamical system has multiple lines of equilibria or no equilibrium when the system parameters are appropriately selected, and the multi-scroll hidden attractors and multi-wing hidden attractors have nothing to do with the system equilibria. Particularly, the numbers of multi-scroll hidden attractors and multi-wing hidden attractors are sensitive to the transient simulation time and the initial values. Dynamical properties of the system, such as phase plane, time series, frequency spectra, Lyapunov exponent, and Poincar′e map, are studied in detail. In addition, a state feedback controller is designed to select multiple hidden attractors within a long enough simulation time. Finally, an electronic circuit is realized in Pspice, and the experimental results are in agreement with the numerical ones.
基金Supported by the National Natural Science Foundation of China under Grant No. 49875018.
文摘Using a coupled ocean-atmosphere model simplified, and the low spectrummethod and the equilibria theory, we discussed the interaction of South Asian winter and summermonsoons with sea surface tempera-ture(SST) seasonal variation in the neighbor sea area. The resultsindicate that, when the winter monsoon is strong, the winter SST is low, and the SST will also below next summer; and vice versa. When the summer monsoon is strong, the summer SST is high; and viceversa. It is inconspicuous for SST in winter that summer monsoon is strong or weak.Ocean-atmosphere interaction reinforces winter and summer monsoons, while meridional SST gradientreinforces winter monsoon and weakens summer monsoon.
