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Primary crystallization process of rapidly solidified Al-Ni-Cu-Nd metallic glasses under continuous heating regime

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中国有色金属学会会刊：英文版 2003年第4期13卷 764-768页

作者：肖于德黎文献 D.Jacovkis N.Clavaguera M.T.Clavaguera-Mora J.Rodriguez-Viejo School of Materials science and Engineering Grup de fisica de Materials I fisica de l'Estat Solid

Rapidly solidified Al 87 Ni 7Cu 3Nd 3 metallic glasses were prepared by using melt spinning. Its calorimetric behavior was characterized by using differential scanning calorimeter. The metallic glasses were partially crystallized under continuous heating regime. Primary crystallization was studied through structural characterization of the amorphous and partially crystallized ribbons by means of conventional X ray diffraction and transmission electron microscopy with selected area electron diffraction. The results show that, the as spun ribbons are fully amorphous and homogeneous on the micron scale, but contain high density of nanoscale quenched in clusters or crystallite embryos. Primary crystallization mainly leads to formation of two phase mixture of α Al nanocrystalline and residual amorphous phase. Precipitation of α Al nanoparticles is limited by build up and overlapped diffusion field of solute atoms with low diffusion rate. At the earlier stage of primary crystallization the crystal nuclei exhibit high density and growth rate. With the α Al crystal growing, the crystal growth rate decreases, and even at the later stage further crystallization into α Al crystal becomes difficult to occur due to thermal stabilization of the residual nickel and neodymium enriched amorphous phase, the saturated values of crystallized volume fraction and α Al crystal diameter getting to 20%30% and 515 nm.

关键词：铝合金快速凝固连续加热制度结晶过程金属玻璃

Golden Ratio Sinusoidal Sequences and the Multimode Pulsation of the δ Sct Star V784 Cassiopeiae

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Chinese Journal of Astronomy and Astrophysics 2004年第4期4卷 343-348页

作者： JuanGarcíaEscudero departamento de fisica Universidad de Oviedo33007-Oviedo Spainon

Non periodic ordered sequences obtained by production rules in formal grammars are applied to the analysis of the multi-periodicity of the δ-Scuti type variable star V784 Cas. An artificial light curve for V784 Cas is generated by a non deterministic derivation in a context-sensitive grammar by concatenation of two sinusoidal fragments following certain word sequences. The two basic building blocks represent temporal segments in a golden ratio and the number of long and short segments in a word are also in a golden ratio.

关键词： stars:variables:δScuti-stars:individual:V784 Cas

Is X(3872) a bound state?

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Chinese Physics C 2019年第12期43卷 115-120页

作者： Pablo G.Ortega Enrique Ruiz Arriola Grupo de fisica Nuclear and Instituto Universitario de fisica Fundamental y Matematicas(IUFFyM) Universidad de SalamancaE-37008 SalamancaSpain departamento de fisica Atomica Molecular y Nuclear and Instituto Carlos I de Fisica Teorica y ComputacionalUniversidad de GranadaE-18071 GranadaSpain

All existing experimental evidence for the bound state nature of X(3872)relies on observing its decay products,which are measured with a finite experimental mass resolution that is typically△m≥2 MeV,and much larger than its alleged binding energy,BX=0.00(18)*** the other hand,we have found recently that there is a clear cancellation in the 1^++channel of the invariant DD^*mass around the threshold between continuum and the bound *** is very much like a similar cancellation in the proton-neutron continuum with the deuteron in the 1^++*** on comparative fits with a common Tsallis distribution of the experimental cross-sections for prompt production of deuterons and X(3872)in pp collisions with a finite pT,we find a strong argument for questioning the bound state nature of this state,which also suggests that the large observed production rate could be consistent with a half-bound state.

关键词： charmonium molecular states particle production Tsallis distribution

Magnetic polarization of a Mn-doped semiconductor nanostructure controlled by an external bias

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Journal of Semiconductors 2015年第7期36卷 22-28页

作者： P.Paradeo Unstituto de fisica Universidad Nacional Autonoma de Mexico

The interplay between the electric and magnetic properties in a double quantum well heterostructure doped by magnetic ions is theoretically investigated. In this material, the magnetism is mediated by the hole gas. The total magnetic polarization of the system is controllable by an external applied bias. The device has two equilibrium states （symmetric and antisymmetric configurations）. In the stable configuration （anti-ferromagnetic type）, the particle spin distribution is reversed in the adjacent wells. The stability of the system is investigated by simulating the interaction of the hole gas with the light. By using an ab initio method, we estimate the switching time of the device.

关键词： magnetic polarization quantum well stability

A Note on Teleportation of an Arbitrary Two-Particle State Without Bell-State Measurement in Cavity QED

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Communications in Theoretical Physics 2009年第8期52卷 241-243页

作者： A.D.dSouza W.B.Cardoso A.T.Avelar B.Baseia Instituto de fisica Universidade Federal de Goias

We present a scheme using four two-level atoms and a bimodal cavity to get approximate conditional teleportation of an arbitrary entangled atomic state without using the Bell-state measurement.

关键词： teleportation Bell-state bimodal cavity

devitrification process in rapidly solidified Al-Ni-Cu-Nd metallic glass

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Journal of Central South University of Technology 2003年第3期10卷 163-167页

作者：肖于德黎文献 D.Jacovkis N.Clavaguera M.T.Clavaguera-Mora J.Rodriguez-Viejo College of Materials Science and Engineering Central South University Changsha 410083 China Grup de Fisica de Materials I Departament de FisicaUniversitat Autonoma de Barcelona 08193 Bellaterra Spain fisica de l'Estat Solid Facultat de Fisica Universitat de BarcelonaDiagonal 647 08028 Barcelona Spain College of Materials Science and Engineering Central South University Changsha 410083 China Grup de fisica de Materials I Departament de Fisica Universitat Autonoma de Barcelona 08193 Bellaterra Spain fisica de l'Estat Solid Facultat de Fisica Universitat de Barcelona Diagonal 647 08028 Barcelona Spain)

In the present study, rapidly solidified ribbons of Al87 Ni7Cu3 Nd3 metallic glass was prepared by usingmelt spinning. devitrification process of the totally amorphous ribbons was investigated by high temperature X-raydiffraction analysis, combining with differential scanning calorimetry, under continuous and isothermal heating re-gime. The X-ray diffraction intensity and full width at the half maximum (FWHM) were analyzed to investigate theincrease of crystallized amount and growth of α-Al crystal particles. The results show that under continuous heatingregime, the metallic glass devitrifies via two main stages: primary crystallization, resulting in two-phase mixture ofα-Al plus residual amorphous phase, and secondary crystallization, corresponding to rapid precipitation of some in-ter-metallic phases in the form of dispersion or eutectic mixture. Under isothermal heating regime, only Al crystalprecipitates from the Al-rich amorphous matrix at low temperature, and when heating at 280 ℃ only Al crystal pre-cipitates within a short time, and then Al8 Cu4 Nd forms, followed by Al3 Ni, in the residual amorphous phase. Whenheating at higher temperature or for longer time, Aln Nd3 forms, the amorphous phase disappears, and the ribbonsdevelop into polycrystalline morphologies with multiply phase mixture of a-Al, Al8 Cu4 Nd, Al3 Ni, and Al11 Nd3.

关键词： rapid solidification Al-rich amorphous alloy devitrification process phase transformation

Fibonacci Sequences and the Multiperiodicity of the Variable Star UW Herculis

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Chinese Journal of Astronomy and Astrophysics 2003年第3期3卷 235-240页

作者： Juan Garcia Escudero departamento de fisica Universidad de Oviedo 33007 Oviedo Spain

We present an application of the methods recently developed for the study of quasicrystal structures to the analysis of multiperiodicity of semiregular variables. A light curve analysis of UW Her shows frequencies that can be included within the general scheme characterizing the Fourier spectra of Fibonacci quasiperiodic sequences. The analysed data come from the BAA Variable Star Section computerised archive.

关键词： stars: variables

Neural Network Based on Quantum Chemistry for Predicting Melting Point of Organic Compounds

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Chinese Journal of Chemical Physics 2009年第1期22卷 19-26页

作者： Juan A. Lazzus departamento de fisica Universidad de La Serena Casilla 554 La Serena Chile

The melting points of organic compounds were estimated using a combined method that includes a backpropagation neural network and quantitative structure property relationship （QSPR） parameters in quantum chemistry. Eleven descriptors that reflect the intermolecular forces and molecular symmetry were used as input variables. QSPR parameters were calculated using molecular modeling and PM3 semi-empirical molecular orbital theories. A total of 260 compounds were used to train the network, which was developed using MatLab. Then, the melting points of 73 other compounds were predicted and results were compared to experimental data from the literature. The study shows that the chosen artificial neural network and the quantitative structure property relationships method present an excellent alternative for the estimation of the melting point of an organic compound, with average absolute deviation of 5%.

关键词： Melting point Quantitative structure-property relationship Artificial neural network Quantum chemistry

Consequences of a two-time relativistic Bohmian model

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Communications in Theoretical Physics 2024年第7期76卷 63-73页

作者： Giuseppe Raguni departamento de fisica Universidad de MurciaE-30071 MurciaSpain

Effects of a Bohmian type quantum-relativistic theory are *** model is obtained by introducing a new and independent time parameter whose relative motions are not directly observable and cause quantum uncertainties of the physical *** the usual de Broglie-Bohm theories,the Quantum Potential does not directly affect the observable motion,but determines the one that is relative to the new time *** turns out that the Zitterbewegung of a free particle,of which a more general law is obtained,is the key example of these hidden motions and,through it,it seems possible to give physical reality to the Feynman's paths.A relativistic revision of the uncertainty principle is also derived from the theory.

关键词： Quantum Mechanics Foundations de Broglie-Bohm theory Zitterbewegung uncertainty principle verification extra dimensions