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32 results on '"Zha, Chao"'

3. Coupling Constants in Asymptotic Expansions

Author

Zha, Chao-Zheng

Subjects
High Energy Physics - Theory
Abstract

Perturbation theory is a powerful tool in manipulating dynamical system. However, it is legal only for infinitesimal perturbations. We propose to dispose this problem by means of perturbation group, and find that the coupling constant approaches to zero in the limit of high order perturbations as Dyson once expected., Comment: Author's e-mail: czz@xju.edu.cn, minor changes

Published
2005

12. Perpendicular Exchange Coupling in TbFeCo/FePt Bilayer Films

Author

Gan Fu-xi, Liu Yao-Wen, Ma Bin, Zha Chao-Lin, Gao Tie-Ren, Jin Qing-Yuan, Zhang Yi-Song, and Zhang Zong-Zhi

Subjects
Condensed Matter::Materials Science, Magnetization, Magnetic anisotropy, Materials science, Kerr effect, Ferromagnetism, Condensed matter physics, Ferrimagnetism, Condensed Matter::Superconductivity, Film plane, Bilayer, Perpendicular, General Physics and Astronomy
Abstract

We investigate the structure and exchange coupling in TbFeCo/FePt bilayer films. It is found that FePt has the L10 structure and the easy axis of the FePt film is perpendicular to the film plane. Results of the vibrating sample magnetometer and the magneto-optical Kerr effect measurements show a strong perpendicular exchange coupling between the ferrimagnetic TbFeCo layer and the hard ferromagnetic FePt layer. The magnetization direction of each layer and the process of magnetization reversal are discussed in detail. The switching field dependence on the exchange coupling has been modelled by micromagnetic simulation and the interlayer coupling constant is about -0.9 erg/cm2 according to this simulation.

Published
2006

13. Nanoindentation study on mechanical properties and curing depth of dental resin nanocomposites.

Author

Zha, Chao, Hu, Jianhua, Li, Ainong, Huang, Shangyu, Liu, Hanxing, Chen, Gang, Zhang, Zuoqi, Li, Bei, and Wang, Zhengzhi

Subjects
*DENTAL resins, *COMPOSITE materials, *ELASTIC modulus, *NANOPARTICLES, *POLYMERS
Abstract

Mechanical properties and curing depth of bisphenol‐α‐glycidyl methacrylate/triethylene glycol dimethacrylate‐based dental composites were systematically investigated by site‐specific nanoindentation tests. Effects of filler (20‐nm silica nanoparticle) content on the nanohardness and elastic modulus of the composites were studied in comparison with micromechanics theoretical models. Results showed that the incorporation of the silica nanoparticles at low contents (up to 5.66 vol%) significantly increases the hardness and elastic modulus of the dental composites by up to 65% and 30%, respectively. It was found that the Counto model gave good predictions for the composite modulus as a function of filler content. For the specific composites studied here, the depth of cure increases approximately linearly with the filler content, which may be ascribed to the stronger reinforcement effect of the silica nanoparticles on the dental composites at a higher particle content. These results combined demonstrate the effectiveness of silica nanoparticles as the reinforcement for dental restorative materials even at small volume fractions. POLYM. COMPOS., 40:1473–1480, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Published
2019
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14. Continuous Quantum Nondemolition Measurements of a Particle in Electromagnetic and Gravitational Fields

Author

Zha Chao-Zheng and Zhu Chun-hua

Subjects
Physics, Formalism (philosophy of mathematics), Physics and Astronomy (miscellaneous), Gravitational field, Quantum mechanics, Path integral formulation, Propagator, Physics::Atomic Physics, Quantum
Abstract

The detection of a particle in electromagnetic plus gravitational fields is investigated. We obtain a set of quantum nondemolition variables. The continuous measurements of these nondemolition parameters are analyzed in the framework of restricted path integral formalism. We manipulate the corresponding propagators, and deduce the probabilities associated with the possible measurement outputs.

Published
2005

15. A new extension of the high-order Virasoro algebra

Author

Zha Chao-Zheng, Wang Hong, and Xu Zhaoxin

Subjects
Pure mathematics, General Mathematics, Holomorphic function, General Physics and Astronomy, Virasoro algebra, Extension (predicate logic), High order, Differential (mathematics), Vector space, Mathematics
Abstract

This paper investigates the high order differential neighbourhoods of holomorphic mappings from S1 × S1 to a vector space and gives a new extension of the high-order Virasoro algebra.

Published
2001

16. W ∞ Algebra and High-Order Virasoro Algebra

Author

Wang Hong, Zha Chao-Zheng, and Zhao Weizhong

Subjects
Pure mathematics, Physics and Astronomy (miscellaneous), Current algebra, W-algebra, Universal enveloping algebra, N = 2 superconformal algebra, Filtered algebra, High Energy Physics::Theory, Nonlinear Sciences::Exactly Solvable and Integrable Systems, Mathematics::Quantum Algebra, Cellular algebra, Virasoro algebra, Mathematics::Representation Theory, Supersymmetry algebra, Mathematics
Abstract

We give the relation between W∞ algebra and high-order Virasoro algebra (HOVA), i.e., W∞ algebra is the limit of HOVA. Then we give the super high-order Virasoro algebra from super W∞ algebra.

Published
1999

23. Magnetic and magneto-optical properties of perpendicularly c-axis orientated FePt thin films

Author

Zhang Zong-Zhi, Wang Shu-Hua, Gao Jing, Zha Chao-Lin, Jin Qing-Yuan, and Ma Bin

Subjects
Condensed Matter::Materials Science, Hysteresis, Materials science, Condensed matter physics, Perpendicular, General Physics and Astronomy, Substrate (electronics), Thin film, Coercivity, Sputter deposition, Anisotropy, Single crystal
Abstract

A series of FePt thin films with perpendicular c-axis orientation were deposited on single crystal MgO (001) substrates by DC magnetron sputtering. With the increase of substrate temperature during deposition, FCC disordered structure transforms to FCT ordered structure (L10 phase) gradually, and the chemical ordering parameter increases simultaneously. Furthermore, the magneto-crystalline anisotropy, coercivity and squareness ratio of the hysteresis loops along perpendicular direction increase also. The magneto-optical Kerr spectra were found to be changing notablely with the chemical ordering of FePt films.

Published
2007

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