Poly （ m-phenylene isophthalamine） （PMIA） and Poly（ p-phenylene terphthalamine） （PPTA） are among the most important high-temperature resistant aramid fibers. The pyrolysis behaviors of these two fibers under i...Poly （ m-phenylene isophthalamine） （PMIA） and Poly（ p-phenylene terphthalamine） （PPTA） are among the most important high-temperature resistant aramid fibers. The pyrolysis behaviors of these two fibers under inert gases were studied using pyrolysis-gas chromatography/mass spectrometry （Py-GC/MS） and thermogravimetric analysis coupled with mass spectrometry （ TGA-DTA/MS ）. The pyrolysis processes of PMIA and PPTA are distinguishing, and the stepwise pyrolysates reflect these differences. A mechanism system of pyrolysis is suggested, which involving hydrolysis and homolysis, At low pyrolysis temperatures, hydrolysis is a primary reaction, and it is very noticeable in the first-step pyrolysis region of PMIA. Elevating pyrolysis temperature, homolysis is enhanced and keep a large advantage in the high temperature range. On the other hand, at higher temperatures, carbonization happens and the homolysis and carbonization of PPTA are emphasized more than of PMIA.展开更多
In order to study the morphological variations among wild Anthocidaris crassispina groups in the southeast coast of China, six groups collected from Daya Bay, Egong Bay, Hailing Island, and Nan＇ao Island in Guangzhou...In order to study the morphological variations among wild Anthocidaris crassispina groups in the southeast coast of China, six groups collected from Daya Bay, Egong Bay, Hailing Island, and Nan＇ao Island in Guangzhou Province, Weizhou Island in Guangxi Province and Ningde City in Fujian Province were analyzed in this paper. Six morphometric traits were measured and the degrees of morphological variations among wild Anthocidaris crassispina groups were compared using four multivariate analyses, one-way ANOVA analysis, variation coefficient method, cluster analysis and discriminant analysis. The results of one-way ANOVA analysis showed that there were significant differences in the six morphometric traits between Weizhou Island＇s population and the other five groups. The variation coefficient analysis showed that the difference between the Weizhou Island＇s population and Hailing Is- land＇s population reached the interspecific level. The results of cluster analysis showed that the morphometric characters of Daly Bay＇s population, Egong Bay＇s population and Nan＇ao＇s population were more similar, but the groups from Weizhou Island and Ningde City were the most divergent. The discriminant analysis showed that the identification accuracy of A. crassispina was 47.8%-86%, and the total dis- criminant accuracy was 65.3%. All the analysis results above suggest that certain morphological variation has been generated among A. crassispina groups from differ- ent origins due to geographical isolation and different environmental factors.展开更多
The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with ...The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with MS Windows as workbench in a PC computer. It has been developed using visual C++ with FoxPro hybrid coding technique.KinPreGSR combines the characteristics of gas/solid reactions with the kinetic models as well as mass and heat transfer equations. The database files were established for the apparent activation energies of some reduction and decomposition reactions to allow the prediction of the reaction kinetics to some extents. Outputs can be displayed using graphical or numerical forms. Examples regarding the oxide reduction and carbonate decomposition under isothermal conditions are given to show those functions.展开更多
Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical sol...Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical solutions are separately obtained in these three zones and then asymp- totically matched. In the asymptotic analysis, we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius. This cor- relation is compared with previous results derived in the limit of infinite value of activation energy. Based on this correla- tion, the properties of spherical flame propagation are inves- tigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed. Moreover, the accuracy and performance of different mod- els used in the spherical flame method are examined. It is found that in order to get accurate laminar flame speed and Markstein length, non-linear models should be used.展开更多
This paper studies the effect of amplitude-phase errors on the antenna performance. Via builting on a worst-case error tolerance model, a simple and practical worst error tolerance analysis based on the chaos-genetic ...This paper studies the effect of amplitude-phase errors on the antenna performance. Via builting on a worst-case error tolerance model, a simple and practical worst error tolerance analysis based on the chaos-genetic algorithm （CGA） is proposed. The proposed method utilizes chaos to optimize initial population for the genetic algorithm （GA） and introduces chaotic disturbance into the genetic mutation, thereby improving the ability of the GA to search for the global optimum. Numerical simulations demonstrate that the accuracy and stability of the worst-case analysis of the proposed approach are superior to the GA. And the proposed algorithm can be used easily for the error tolerant design of antenna arrays.展开更多
Based on the traditional scheme for a nonlinear system with multiple time scales, the enveloping slow-fast analysis method is developed in the paper, which can be employed to investigate the dynamics of nonlinear fiel...Based on the traditional scheme for a nonlinear system with multiple time scales, the enveloping slow-fast analysis method is developed in the paper, which can be employed to investigate the dynamics of nonlinear fields with multiple time scales with periodic excitation. Upon using the method, the behaviors of the kinetic model of CO oxidation on the platinum group metals have been explored in detail. Two typicM bursting phenomena such as Fold/Fold/Hopf bursting and Fold/Fold bursting, are presented, the bifurcation mechanisms of which have been obtained. Furthermore, the dynamic difference between the two cases corresponding to relatively large and small perturbation frequencies, respectively, has been presented, which can be used to describe the influence of the frequencies involving in the evolution on the bursting behaviors in the system.展开更多
文摘Poly （ m-phenylene isophthalamine） （PMIA） and Poly（ p-phenylene terphthalamine） （PPTA） are among the most important high-temperature resistant aramid fibers. The pyrolysis behaviors of these two fibers under inert gases were studied using pyrolysis-gas chromatography/mass spectrometry （Py-GC/MS） and thermogravimetric analysis coupled with mass spectrometry （ TGA-DTA/MS ）. The pyrolysis processes of PMIA and PPTA are distinguishing, and the stepwise pyrolysates reflect these differences. A mechanism system of pyrolysis is suggested, which involving hydrolysis and homolysis, At low pyrolysis temperatures, hydrolysis is a primary reaction, and it is very noticeable in the first-step pyrolysis region of PMIA. Elevating pyrolysis temperature, homolysis is enhanced and keep a large advantage in the high temperature range. On the other hand, at higher temperatures, carbonization happens and the homolysis and carbonization of PPTA are emphasized more than of PMIA.
基金Supported by National Key Technology Research and Development Program(2012BAD18B02,2012BAD18B01-2)Special Scientific Research Fund of Marine Public Welfare Profession of China(201205021-3)National Nonprofit Institute Research Grant of CATAS-TCGRI(2015TS05)~~
文摘In order to study the morphological variations among wild Anthocidaris crassispina groups in the southeast coast of China, six groups collected from Daya Bay, Egong Bay, Hailing Island, and Nan＇ao Island in Guangzhou Province, Weizhou Island in Guangxi Province and Ningde City in Fujian Province were analyzed in this paper. Six morphometric traits were measured and the degrees of morphological variations among wild Anthocidaris crassispina groups were compared using four multivariate analyses, one-way ANOVA analysis, variation coefficient method, cluster analysis and discriminant analysis. The results of one-way ANOVA analysis showed that there were significant differences in the six morphometric traits between Weizhou Island＇s population and the other five groups. The variation coefficient analysis showed that the difference between the Weizhou Island＇s population and Hailing Is- land＇s population reached the interspecific level. The results of cluster analysis showed that the morphometric characters of Daly Bay＇s population, Egong Bay＇s population and Nan＇ao＇s population were more similar, but the groups from Weizhou Island and Ningde City were the most divergent. The discriminant analysis showed that the identification accuracy of A. crassispina was 47.8%-86%, and the total dis- criminant accuracy was 65.3%. All the analysis results above suggest that certain morphological variation has been generated among A. crassispina groups from differ- ent origins due to geographical isolation and different environmental factors.
基金supported by the National Natural Science Foundation of China(No.59774023).
文摘The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with MS Windows as workbench in a PC computer. It has been developed using visual C++ with FoxPro hybrid coding technique.KinPreGSR combines the characteristics of gas/solid reactions with the kinetic models as well as mass and heat transfer equations. The database files were established for the apparent activation energies of some reduction and decomposition reactions to allow the prediction of the reaction kinetics to some extents. Outputs can be displayed using graphical or numerical forms. Examples regarding the oxide reduction and carbonate decomposition under isothermal conditions are given to show those functions.
基金supported by the National Natural Science Foundation of China (50976003,51136005)Doctoral Fund of Ministry of Education of China (20100001120003)
文摘Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical solutions are separately obtained in these three zones and then asymp- totically matched. In the asymptotic analysis, we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius. This cor- relation is compared with previous results derived in the limit of infinite value of activation energy. Based on this correla- tion, the properties of spherical flame propagation are inves- tigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed. Moreover, the accuracy and performance of different mod- els used in the spherical flame method are examined. It is found that in order to get accurate laminar flame speed and Markstein length, non-linear models should be used.
基金supported by the National Natural Science Foundation of China (60901055)
文摘This paper studies the effect of amplitude-phase errors on the antenna performance. Via builting on a worst-case error tolerance model, a simple and practical worst error tolerance analysis based on the chaos-genetic algorithm （CGA） is proposed. The proposed method utilizes chaos to optimize initial population for the genetic algorithm （GA） and introduces chaotic disturbance into the genetic mutation, thereby improving the ability of the GA to search for the global optimum. Numerical simulations demonstrate that the accuracy and stability of the worst-case analysis of the proposed approach are superior to the GA. And the proposed algorithm can be used easily for the error tolerant design of antenna arrays.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 20976075,20976041,and 10972091)
文摘Based on the traditional scheme for a nonlinear system with multiple time scales, the enveloping slow-fast analysis method is developed in the paper, which can be employed to investigate the dynamics of nonlinear fields with multiple time scales with periodic excitation. Upon using the method, the behaviors of the kinetic model of CO oxidation on the platinum group metals have been explored in detail. Two typicM bursting phenomena such as Fold/Fold/Hopf bursting and Fold/Fold bursting, are presented, the bifurcation mechanisms of which have been obtained. Furthermore, the dynamic difference between the two cases corresponding to relatively large and small perturbation frequencies, respectively, has been presented, which can be used to describe the influence of the frequencies involving in the evolution on the bursting behaviors in the system.
