Monitoring indoor harmful gas can obtain the infrared spectra of mixed harmful gases.Since the absorption bands of mixed gases overlap and their qualitative and quantitative analyses are not easy,feature extraction me...Monitoring indoor harmful gas can obtain the infrared spectra of mixed harmful gases.Since the absorption bands of mixed gases overlap and their qualitative and quantitative analyses are not easy,feature extraction method based on joint approximative diagonalization of eigenmatrix（JADE）is proposed.By fully mining the hidden information of original data and analyzing higher-order statistics information of the data,each substance spectrum in the mixed gas can be accurately distinguished.In addition,a multi-dimensional data quantitative analysis model of the extracted independent source is established by using support vector machine（SVM）based on regular theory.The experimental results show that the correlation coefficients of the components of mixed gases is above 0.999 1by quantitative analysis,which verifies the accuracy of this feature extraction method.展开更多
In this paper, using a Gaussian distribution of wave normal angle X=tan0, and considering contributions of harmonic resonances n up to ＋5, we analyze the effect of normal angle on diffusion coefficients induced by gy...In this paper, using a Gaussian distribution of wave normal angle X=tan0, and considering contributions of harmonic resonances n up to ＋5, we analyze the effect of normal angle on diffusion coefficients induced by gyroresonance between chorus waves and electrons with energies 0.1 and 1.0 MeV on the dayside and nightside at L=4.5. When pitch angle a~〉10~, for 0.1 and 1,0 MeV electrons on the dayside and nightside, diffusion coefficients of five orders （-2, -1, 0, 1, 2） decrease with in- creasing normal angle peak, leading to the total diffusion coefficients decreasing with increasing peak. When ae〈10~, for 1.0 MeV electrons on the dayside and 0.1 MeV electrons on the dayside and nightside, the positive order diffusion coefficients are generally smaller than the same negative order ones; in the meanwhile, diffusion coefficients of orders （-2, 1, 2） are very small, the dominant order n=-I diffusion coefficients change very little, hence the total diffusion coefficients almost remain un- changed. However, for 1.0 MeV electrons on the nightside, diffusion coefficients of orders （-2, 1, 2） which are larger than those of the order （-1） resonance increase with increasing peak, hence the total diffusion coefficients increase with increasing peak. The current results show that the wave normal angle plays an important role in the quantitative analysis of gyroresonance between chorus waves and electrons in the outer radiation belt.展开更多
Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magne-tostrictive transducers due to their attractive properties such as magnetic field induced sha...Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magne-tostrictive transducers due to their attractive properties such as magnetic field induced shape memory effect and large magnetocaloric effect. The properties of these alloys （e.g., the martensitic transformation temperature TM） sensitively depend on the composition. Understanding the composition dependence of these properties so as to design the alloy as desired is one of the main research topics in this area. In recent years, we have investigated the composition dependent elastic modulus and phase stability of Ni2MnGa-based alloys by using a first-principles method, in hope of clarifying their connection to the properties of these alloys. In this article, we review the main results of our investigations. We show that the tetragonal shear modulus C＇ is a better predictor of the composition dependent TM than the number of valence electrons per atom （e/a） since the general TM-C＇ correlation works for some of the alloys for which the TM-ela correlation fails, although there exist several cases for which both the general TM-C＇ and TM-ela correlations break down. Employing the experimentally determined modulation function, the complex 5-layer modulated （5M） structure of the martensite of Ni2MnGa and the Al-doping effect on it are studied. We find that the shuffle and shear of the 5M structure are linearly coupled. The relative stability of the austenite and the marten- sites is examined by comparing their total energies. The non-modulated martensite β＇″ with the tetragonality of the unit cell c/a〉1 is shown to be globally stable whereas the 5M martensite with c/a〈1 is metastable. The critical Al atomic fraction over which the martensitic transformation between the 5M martensite and austenite cannot occur is predicted to be 0.26, in reason- able agreement with experimental findings.展开更多
基金National Natural Science Foundation of China(No.61127015)
文摘Monitoring indoor harmful gas can obtain the infrared spectra of mixed harmful gases.Since the absorption bands of mixed gases overlap and their qualitative and quantitative analyses are not easy,feature extraction method based on joint approximative diagonalization of eigenmatrix（JADE）is proposed.By fully mining the hidden information of original data and analyzing higher-order statistics information of the data,each substance spectrum in the mixed gas can be accurately distinguished.In addition,a multi-dimensional data quantitative analysis model of the extracted independent source is established by using support vector machine（SVM）based on regular theory.The experimental results show that the correlation coefficients of the components of mixed gases is above 0.999 1by quantitative analysis,which verifies the accuracy of this feature extraction method.
文摘In this paper, using a Gaussian distribution of wave normal angle X=tan0, and considering contributions of harmonic resonances n up to ＋5, we analyze the effect of normal angle on diffusion coefficients induced by gyroresonance between chorus waves and electrons with energies 0.1 and 1.0 MeV on the dayside and nightside at L=4.5. When pitch angle a~〉10~, for 0.1 and 1,0 MeV electrons on the dayside and nightside, diffusion coefficients of five orders （-2, -1, 0, 1, 2） decrease with in- creasing normal angle peak, leading to the total diffusion coefficients decreasing with increasing peak. When ae〈10~, for 1.0 MeV electrons on the dayside and 0.1 MeV electrons on the dayside and nightside, the positive order diffusion coefficients are generally smaller than the same negative order ones; in the meanwhile, diffusion coefficients of orders （-2, 1, 2） are very small, the dominant order n=-I diffusion coefficients change very little, hence the total diffusion coefficients almost remain un- changed. However, for 1.0 MeV electrons on the nightside, diffusion coefficients of orders （-2, 1, 2） which are larger than those of the order （-1） resonance increase with increasing peak, hence the total diffusion coefficients increase with increasing peak. The current results show that the wave normal angle plays an important role in the quantitative analysis of gyroresonance between chorus waves and electrons in the outer radiation belt.
基金supported by the MoST of China (Grant No. 2011CB606404)the National Natural Science Foundation of China (Grant No. 50871114)
文摘Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magne-tostrictive transducers due to their attractive properties such as magnetic field induced shape memory effect and large magnetocaloric effect. The properties of these alloys （e.g., the martensitic transformation temperature TM） sensitively depend on the composition. Understanding the composition dependence of these properties so as to design the alloy as desired is one of the main research topics in this area. In recent years, we have investigated the composition dependent elastic modulus and phase stability of Ni2MnGa-based alloys by using a first-principles method, in hope of clarifying their connection to the properties of these alloys. In this article, we review the main results of our investigations. We show that the tetragonal shear modulus C＇ is a better predictor of the composition dependent TM than the number of valence electrons per atom （e/a） since the general TM-C＇ correlation works for some of the alloys for which the TM-ela correlation fails, although there exist several cases for which both the general TM-C＇ and TM-ela correlations break down. Employing the experimentally determined modulation function, the complex 5-layer modulated （5M） structure of the martensite of Ni2MnGa and the Al-doping effect on it are studied. We find that the shuffle and shear of the 5M structure are linearly coupled. The relative stability of the austenite and the marten- sites is examined by comparing their total energies. The non-modulated martensite β＇″ with the tetragonality of the unit cell c/a〉1 is shown to be globally stable whereas the 5M martensite with c/a〈1 is metastable. The critical Al atomic fraction over which the martensitic transformation between the 5M martensite and austenite cannot occur is predicted to be 0.26, in reason- able agreement with experimental findings.
