The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/M...The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/MS). PGC was applied to study the F t curve of the multiblock copolymer and PGC/MS was used to separate and identify the pyrolyzates. DTA experiment was used to study the decomposition temperature. The results show that the beginning point of elastomer’s decomposition was about 300?℃ and the decomposition temperature of most of the sample was 550?℃. Many pyrolyzates were produced because of the breaking of weak bonds in the sample. The possible microstructure was verified and the pyrolysis pathway of the copolymer was investigated.展开更多
[Objective] To establish the comprehensive evaluation index system of public green area per capita as a quantitative mean of measuring ecological city and livable city. [Method]The GM (1, 1) forecasting model was set ...[Objective] To establish the comprehensive evaluation index system of public green area per capita as a quantitative mean of measuring ecological city and livable city. [Method]The GM (1, 1) forecasting model was set up according to statistics of public green area per capita in Xi’an City during 1996 and 2005, on this basis, the development trend of green area per capita in Xi’an City until 2015 were analyzed in case of no any changing factors or conditions. [Result]Grey forecasting model was established as, (t = 0, 1, …, n); model parameters as a = - 0.031 71, u = 4.139 17. After residual error test and posterior-variance-test, the precision of this model is proved fairly good. [Conclusions]According to this model, public green area per capita in Xi’an City will achieve 7.66 m2 by 2015, which is still far away from the livable city index (16 m2 per capita) and should be paid more attention by the local government, the construction of urban green areas should be further enhanced, more vegetations should be cultivated so as to improve the urban green coverage ratio.展开更多
A single-mode laser noise model driven by quadratic colored pump noise and biased amplitude modulationsignal is proposed.The analytic expression of signal-to-noise ratio is calculated by using a new linearized procedu...A single-mode laser noise model driven by quadratic colored pump noise and biased amplitude modulationsignal is proposed.The analytic expression of signal-to-noise ratio is calculated by using a new linearized procedure.Itis found that there are three different typies of stochastic resonance in the model:the conventional form of stochasticresonance,the stochastic resonance in the broad sense,and the bona fide SR.展开更多
文摘The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/MS). PGC was applied to study the F t curve of the multiblock copolymer and PGC/MS was used to separate and identify the pyrolyzates. DTA experiment was used to study the decomposition temperature. The results show that the beginning point of elastomer’s decomposition was about 300?℃ and the decomposition temperature of most of the sample was 550?℃. Many pyrolyzates were produced because of the breaking of weak bonds in the sample. The possible microstructure was verified and the pyrolysis pathway of the copolymer was investigated.
文摘[Objective] To establish the comprehensive evaluation index system of public green area per capita as a quantitative mean of measuring ecological city and livable city. [Method]The GM (1, 1) forecasting model was set up according to statistics of public green area per capita in Xi’an City during 1996 and 2005, on this basis, the development trend of green area per capita in Xi’an City until 2015 were analyzed in case of no any changing factors or conditions. [Result]Grey forecasting model was established as, (t = 0, 1, …, n); model parameters as a = - 0.031 71, u = 4.139 17. After residual error test and posterior-variance-test, the precision of this model is proved fairly good. [Conclusions]According to this model, public green area per capita in Xi’an City will achieve 7.66 m2 by 2015, which is still far away from the livable city index (16 m2 per capita) and should be paid more attention by the local government, the construction of urban green areas should be further enhanced, more vegetations should be cultivated so as to improve the urban green coverage ratio.
基金Supported by National Natural Science Foundation of China under Grant No.10275025
文摘A single-mode laser noise model driven by quadratic colored pump noise and biased amplitude modulationsignal is proposed.The analytic expression of signal-to-noise ratio is calculated by using a new linearized procedure.Itis found that there are three different typies of stochastic resonance in the model:the conventional form of stochasticresonance,the stochastic resonance in the broad sense,and the bona fide SR.
