Papers by Author: Ying Jun Gao

Abstract: With properly chosen structural parameters, the transmission spectra of the mirror symmetrical model of photonic crystal (AB)m (CD)n (BA)m is calculated by means of transfer matrix method. When the transmission band of photonic crystal (CD) is inside the band gap of photonic crystal (AB)m (BA)m, both sharing the same central frequency as their symmetry centers, mirror symmetrical photonic quantum well is formed. At both sides of the central frequencies in the reduced units in the transmission spectra of the well, there are odd resonance-peaks, which symmetrically distributed and orderly localized, and show an obvious quantization effect for transmission-peaks. The number and location of the transmission peaks can be modulated by changing the number of period n of photonic crystal (CD). This can be used for designing the adjustably odd-passaged optical filters.

Abstract: By means of the transfer matrix method, transmission spectra and dispersion relationships of photonic crystals (AB) m (CD) n (AB) m (CD) n (AB) m are investigated herein. The number and highness of transmission peaks are found to relate closely with the repeating periodicity n, and (CD)n medium of positive- or negative- refractive index as well. The results may be helpful for designing optical filters of desired properties.

Abstract: The atomic bonding of the segregated cell of Al-Li alloy in earlier ageing condition was calculated according to the empirical electron theory (EET) in solid. The results showed that the strongest covalent bond was the Al-Al bond in the segregated cell without vacancy, while the strongest covalent bond was the Al-Li bond in the cell containing vacancy. Since the difference of electronagativity between the Al and Li atoms was obvious, it was inclined to form the Al-Li segregated cell of short range order structure in the condition of vacancy joining. The short range order structure with vacancy was probably the embryo or precursor structure of the metastable phase ' δ (Al3Li). As the ' δ (Al3Li) was coherence with matrix, the bond net strength was enhanced by the precipitation of ' δ (Al3Li) and hence the alloy was strengthened.

Abstract: Atomic bonding of the GPB zone and S′′ phase of Al-Cu-Mg alloys in early aging stage are calculated using the empirical electron theory (EET) in Solid. The results show that not only the covalence bond-net is very strong in GPB zone, but the whole covalence bond energy of S′′ phase is also very large, all the primary bond-net framework of these precipitates can consolidate the matrix of alloy. Phase transformation from GPB zone to S′′ phase is explained reasonably based on atomic bonding and total binding capacity of Al and Cu atoms in these precipitates.

Abstract: The valence electron structure of GP Zone in Al-Zn alloy was calculated according to the Empirical Electron Theory(EET). The result of valence electron structure was further applied to analyze the interface energy between GP Zone and matrix. The reason that the GP Zones were formed even at the highest quenching speed and the hardness was stably ascended as soon as GP zones were formed and reached the maximum before the precipitation of metastable phase, was that the amoumt of the strongest covalent bond in the GP Zone was far more than that in α-Al cell and the Al atom in GP Zone was easily prone to forming covalent bond with Zn atom. It was an easy and effective method to apply the EET theory with the hardball model to calculation of interface energy.