bluuebunny/crossref_metadata_2025 huggingface dataset:
Documental y denuncia: modelos de mundo en La libertad del diablo y Tempestad
Authors: Méndez Rangel Abigail
Published: December 2020

El género del documental visual es uno de los medios que se han utilizado comodenuncia contra los gobiernos del PRIAN en México y la desastrosa situación social a la quedio lugar. En las páginas que siguen, a la luz de la teoría de los modelos de mundo de ManuelAsensi, se ha llevado a cabo un análisis del documental de Everardo González, La libertad deldiablo (2017), y en menor medida el de Tatiana Huezo, Tempestad, cuyas premisas, silogismosy modelos de mundo están analizados a partir del montaje que nos presentan tales documentales.Los resultados ponen de relieve la capacidad modelizante de estos textos en el marco deuna lucha global por la libertad y la democracia real en México.
Carmen y el sabotaje en el ballet
Authors: Ruiz Castell Julia
Published: December 2020

En 1966 la bailarina rusa Maya Plisetskaya le hizo un encargo al por aquel entonces coreógrafo del Ballet Nacional de Cuba Alberto Alonso: quería encarnar el personaje de Carmen en el ballet. Hasta el momento, la novela de Merimée había sido musicalizada por Bizet en forma de Ópera y existía solo una versión realizada para el ballet en 1949, la del francés Roland Petit. Para ello Alberto Alonso realizó unos “esbozos” de la coreografía en Cuba, con Alicia Alonso, antes de presentarla en la URSS. Y así, nacieron dos propuestas escénicas completamente diferentes bajo un mismo texto coreográfico. El efecto que provoca la experiencia de ver bailar a Alicia Alonso nada tiene nada que ver con la de Plisetskaya, a pesar de la perfección técnica en la interpretación de esta última. ¿Por qué? ¿Qué encierra la interpretación de la cubana que atrae al espectador y singulariza la expresión del cuerpo en movimiento?Como indica Manuel Asensi en su Crítica y sabotaje (2011), “el cine, la televisión, las páginas web, los periódicos (…) son medios a través de los cuales se cumple la acción modeladora de los aparatos ideológicos heterogéneos y plurales del Estado, o del Imperio”, y del mismo modo el discurso de la danza también evidencia la construcción de un modelo de mundo que captura imaginariamente al sujeto a través de una estructura silogística concreta. Así pues, desde el ejercicio práctico de la crítica como sabotaje nos preguntaremos acerca de ¿qué modelo de mundo subyace en la interpretación de Alicia Alonso? ¿Cómo se construye el silogismo en su discurso? ¿Cuál es la dirección ideológica que toma dicha modelización? ¿Y hasta qué punto esta “logra que los individuos participen de ella mediante sus acciones y sus discursos”?
Metodología de la enseñanza de portugués a hablantes de español: un marco y una propuesta de planificación del tratamiento de las competencias lingüísticas
Authors: Alonso Rey Rocío
Published: December 2020

Las propuestas metodológicas en el campo del portugués para hablantes de español resultan demasiado generales o presentan moldes demasiado rígidos para su aplicación en el aula. En este trabajo se desarrolla un modelo de organización de las secuencias para el tratamiento de aspectos competenciales. El marco operacional presentado se basa en las principales especificidades metodológicas del campo y es compatible con diferentes perspectivas y tipos de enseñanza.
Passively Q-switched mode-locked Tm, Ho:LLF laser with a WS2 saturable absorber
Authors: Ling Wei-Jun  , Xia Tao  , Dong Zhong  , Liu Qing  , Lu Fei-Ping  , Wang Yong-Gang  ,   Institute of Laser Technology, Tianshui Normal University, Tianshui 741001, China;,   School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

Using few-layer tungsten disulfide (WS2) doped polyvinyl alcohol as a saturable absorber for the initiation of the pulse generation, we experimentally demonstrate stable passively Q-switched mode-locked operations of Tm, Ho:LiLuF4 laser at 1895 nm for the first time. The laser is designed with an X-type four-mirror cavity and pumped by a Ti:sapphire laser operated at 785 nm, and its continuous operation is initiated when the absorbed pump power is 143 mW. When the absorbed pump power reaches 2.645 W, we obtain a maximum output power of 985 mW and a crystal slope efficiency of 39.8% by linear fitting. When the saturable absorber WS2 is inserted in the cavity, the threshold of the absorbed pump power is increased to 234 mW. With the increase of the pump power, Q-switch pulse sequence is first observed. When the absorbed pump power reaches 1.39 W, the stable operation of the Q-switched mode locked pulse is realized. A maximum average output power of 156 mW is achieved at an absorbed pump power of 2.6 W, which corresponds to a 25 kHz Q-switched repetition rate and a 300 μs-long pulse envelope. In this case, the modulation depth in Q-switching envelopes is close to 100%. After the passively Q-switched mode-locked is obtained stably, the mode-locked pulses inside the Q-switched pulse envelope have a repetition rate of 131.6 MHz, corresponding to a mode locked pulse energy of 1.19 nJ and a cavity length of 1.14 m. According to the definition of the rise time and considering the symmetric shape of the mode locked pulse, we can assume that the duration of the pulse is approximately 1.25 times more than the rise time of the pulse. Then the width of the mode locked pulse is estimated to be about 878 ps. These experimental results show that WS2 is a promising broadband saturable absorption material for generating a 2 μm-wavelength mid-infrared solid-state laser pulse. By increasing the pump power and reducing the loss of WS2 material, it is possible to realize a continuous mode locking operation which has a narrower pulse duration. The mode-locked mid-infrared pulses are very stable and have a lot of potential applications such as ultrafast molecule spectroscopy, mid-IR pulse generation, laser radar, atmospheric environment monitoring, etc.
Photoacoustic temperature measurement based on dual-wavelength method
Authors: Liao Yu  , Jian Xiao-Hua  , Cui Yao-Yao  , Zhang Qi  ,   School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China;,   Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
Published: December 2020

Photoacoustic temperature measurement is a novel technique in which photoacoustic effect is used to measure temperature. It has the advantages of non-invasiveness, high sensitivity and deep penetration depth, which is suitable for monitoring the temperature distribution for the safe deposition of heat energy and efficient destruction of tumor cells during thermotherapy or cryotherapy. However, the present reported methods usually use one single wavelength for photoacoustic temperature measuring and are vulnerable to systematic and environmental influence, including the instability of system caused by fluctuation of laser energy, position displacement of transducer, and tissue complexity, which could reduce the measuring accuracy and stability. To solve this problem, a new photoacoustic temperature measuring method by employing two laser wavelengths is proposed in this paper. Firstly a brief theoretical analysis of dual-wavelengths photoacoustic temperature method is performed based on the linear relationship between photoacoustic signal and tissue temperature under two different wavelengths. Then two different samples including phantom of graphite and ex vivo pig blood are experimented respectively. The experimental temperature is set to be in a range of 26 ℃-48 ℃, which is controlled by a precise hot plate. And for improving the detection accuracy, the dual-wavelengths are selected as 760 and 900 nm for graphite phantom, 820 nm and 860 nm for ex vivo pig blood according to their absorption spectrum repetitively. The obtained results reveal that the temperature measuring correlation coefficients by dual-wavelength method can reach to 0.98 in graphite phantom and 0.99 in ex vivo tissue, respectively. And the average measurement deviation decreases to 0.88 ℃ in dual-wavelength method from 1.31 ℃ for the traditional single wavelength method for graphite phantom. While in ex vivo tissue, the measurement deviation decreases to 0.90 ℃ in dual-wavelength method from the average value 1.45 ℃ for the single wavelength method. Furthermore, the standard deviations of error are respectively reduced by an average of 38% in graphite phantom and an average of 30% in ex vivo tissue, respectively. These results indicate that the dual-wavelength method of photoacoustic temperature measurement can improve both the measuring accuracy and stability, and has a potential to be applied to medical therapy and other biomedical fields.
Energy levels and radiative transitions of the core-excited high-spin states in boron atom (ion)
Authors: Qian Xin-Yu  , Sun Yan  , Liu Dong-Dong  , Hu Feng  , Fan Qiu-Bo  , Gou Bing-Cong  ,   School of Mathematic and Physical Science, Xuzhou University of Technology, Xuzhou 221018, China;,   School of Physics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

Energy levels of the core-excited high-spin Rydberg states (4,5,6L, L = S, P) in boron atom (ion) are calculated by the Rayleigh-Ritz variation method with using large-scale multi-configuration wave functions. The important orbital-spin angular momentum partial waves are selected based on the rule of configuration interaction. The computational convergence is discussed by the example of the contribution from each partial wave in the non-relativistic energy calculations of the high-spin state 1s2s2p2 5Pe in B+ ion. To saturate the wave functional space and improve the non-relativistic energy, the restricted variational method is used to calculate the restricted variational energy. Furthermore, the mass polarization effect and relativistic energy correction are included by using a first-order perturbation theory. The quantum electrodynamic effects and higher-order relativistic contributions to the energy levels are also calculated by the screened hydrogenic formula. Then, the accurate relativistic energy levels of these high-spin states of B atom (ion) are obtained by adding the non-relativistic energy and all corrections. The fine structure splitting of these high-spin states is also calculated by the Breit-Pauli operators in the first-order perturbation theory. Compared with other theoretical results, our calculation results are in good accordance with the experimental data.
The absorption oscillator strengths, emission oscillator strengths, absorption rates, emission rates, and transition wavelengths of the electric-dipole transitions between these high-spin states of B atom (ions) are systematically calculated by using the optimized wave functions. The oscillator strengths and transition rates are obtained in both the length and velocity gauges. By comparing the two gauge results of oscillator strength, we find that there is a good consistency between them when fl 0.3, and a reasonable consistency is obtained when fl 0.3. The accordance between the length and the velocity gauge results reflects that the calculated wave functions in this work are reasonably accurate. The calculated transition data are also compared with the corresponding experimental and other theoretical data. Good agreement is obtained except the wavelengths for two transitions: 1s2p4p 4Se1s2p3d 4P and 1s2p4d 4P1s2p3p 4Pe. The relative differences between our theoretical results and experimental data are 0.7% and 0.3%, respectively. They need to be verified by further theoretical and experimental studies. For some core-excited high-spin states, the related energy levels and transition data are reported for the first time. Our calculation results will provide valuable data for calculating the spectral lines in the relevant experiments.
An adaptive three-Gauss model based on memristive cross array and its application in image enhancement
Authors: Liu Qi  , Wang Li-Dan  , Duan Shu-Kai  ,   Chongqing Key Laboratory of Nonlinear Circuits and Intelligent Information Processing, School of Electronic and Information Engineering, Southweat University, Chongqing 400715, China
Published: December 2020

In visual image processing, there is a three-Gauss model used to simulate the receptive field of retinal ganglion cells, which can realize image enhancement to a certain extent, such as image edge and information about details. However, in dealing with a large number of image data, it is necessary to manually adjust the parameters of the three-Gauss model in order to achieve better results, which is a very tedious and time-consuming process. According to this, in this paper we propose an adaptive three-Gauss model based on memristive cross array. Memristor, whose resistance is controlled by size, polarity and power supply time of the power supply, is a kind of non-volatile component. Moreover, if the voltage applied to both ends of memristor is removed, it can still keep the resistance value when the power is off. Many studies show that when voltage pulses with the different amplitudes and the same width are applied to both ends of the memristor, the resistance will change continuously. This principle is adopted to realize image storage. Therefore, it makes use of the characteristics of memristor in this paper. The proposed model is based on the traditional three-Gauss model and changes the model parameters by using the dynamic characteristics of memristive cross array according to the local characteristics of the image to be processed, in order to achieve the purpose of local optimization and make the whole image obtain better enhancement effect. First of all, according to the local brightness information of the image, the polarity and the width of the pulse voltage required by the memristor are determined. Then, the values of the model parameters corresponding to the memristance can be obtained. Finally, the local enhancement template will be available to realize the enhancement. In this paper, the color and gray images are selected. The qualitative and quantitative experimental results show that the proposed adaptive three-Gauss model based on memristive cross array can not only effectively enhance the edge contour of the image, but also greatly improve the image contrast and clarity. Moreover, it provides a new direction for the application of memristor to image processing.
Co3O4 mesoporous nanostructure supported by Ni foam as high-performance supercapacitor electrodes
Authors: Zhang Cheng  , Deng Ming-Sen  , Cai Shao-Hong  ,   Guizhou Province Key Laboratory of Low Dimensional Condensed Matter Physics of Higher Educational Institution, Guizhou Normal University, Guiyang 550001, China;,   School of Information, Guizhou University of Finance and Economics, Guiyang 550025, China;,   Guizhou Provincial Key Laboratory of Computational Nano-material Science, Guizhou Education University, Guiyang 550018, China
Published: December 2020

In various energy conversion and storage devices, supercapacitors have been extensively used due to their high power densities, fast delivery rates, and exceptionally long cycle lives. However, the low specific capacitances and low energy densities of supercapacitors largely hinder widespread applications in large-scale energy conversion and storage systems. To improve the specific capacitances of the supercapacitors, the surface areas of the electrode materials should be made as large as possible to allow the capturing and releasing of particles (such as ions, molecules, or electric charges). Here in this work, we demonstrate an efficient approach to the large-scale production of Co3O4 mesoporous nanostructure supported by Ni foam via a simple hydrothermal synthesis followed by ambient annealing at 300 ℃ for 4 h. The designed and fabricated Co3O4 mesoporous nanostructures directly serve as binder- and conductive-agent-free electrodes for supercapacitors, which thus provide more chemical reaction sites, shorten the migration paths for electrons and ions, and improve the electrical conductivity. By taking advantage of the structural features and excellent electronic conductivity, the Co3O4 exhibits the ultrahigh specific capacitances (1.87 Fcm-2 (936 Fg-1) and 1.80 Fcm-2 (907 Fg-1) at current densities of 2.5 mAcm-2 and 5.5 mAcm-2, respectively), high rate capacitances (48.37% of the capacitance can be retained when the current density increases from 2.5 mAcm-2 to 100 mAcm-2) and excellent cycling stability (92.3% of the capacitance can be retained after 4000 charge/discharge cycles at a current density of 10 mAcm-2). The nanostructuring approach and utilizing a binder- and conductive-agent-free electrode can be readily extended to other electrochromic compounds of high-performance energy storage devices.
Properties of distribution and entanglement in discrete-time quantum walk with percolation
Authors: An Zhi-Yun  , Li Zhi-Jian  ,   Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, China
Published: December 2020

We investigate one-dimensional discrete-time quantum walk on the line where the links between neighboring sites are randomly broken. Two link-broken ways, static percolation and dynamical percolation, are considered. The former means that the broken links are fixed in position space at each time step, while the latter is that broken links are varied with time step. Our attention focuses on the effects of these disorders on two physical quantities, the probability distribution and the entanglement between the coin degree of freedom and position degree of freedom. Choosing Hadamard coin operator and assuming the walker to start from the position eigenstate|0〉and attach itself to a coherent coin state 1/√2 (|↑〉+ i|↓〉), we give the statistical average results after making numerical calculations many times. The choices of coin operator and initial state, resulting in a symmetric probability distribution about origin in the ideal case, is helpful in comparing with different cases in different disorder strengths. It is shown that the probability distribution of static percolation quantum walk can change from a coherent behavior at short time to Anderson localization at longer time, while the dynamical percolation quantum walk can change to a classical diffusive behavior. With the decrease of the percolation probability, these transitions become faster. The entanglement for ideal case without disorder reaches a constant value after a short time evolution. The static percolation makes the entanglement less than that of ideal case and fluctuate irregularly around a certain value. The situation is very different for the dynamical percolation:the entanglement increases smoothly with the time step and can exceed the constant value in the ideal case at some time. Both of entanglements for two types of percolations decrease with reducing percolation probability. As a striking characteristic, the entanglement in dynamical case can tend to maximum regardless of percolation probability in long time limit, while the static case cannot. In the model for our study, the randomized unitary operations, induced by the static and dynamical percolations, can lead to some noticeable effects on the transport and entanglement of discrete time quantum walk. The results about the interplay between disorder and entanglement not only assist quantum information processing, but also give more options to further explore and understand disorder physical processes in nature.
Fluid convection and solidification mechanisms of liquid Fe50Cu50 alloy under electromagnetic levitation condition
Authors: Lin Mao-Jie  , Chang Jian  , Wu Yu-Hao  , Xu Shan-Sen  , Wei Bing-Bo  ,   Department of Physics, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

In the electromagnetic levitation experiment, the liquid flow in the undercooled liquid alloy remarkably affects the relevant thermodynamic property measurement and solidification microstructure. Therefore, it is of great importance to understand the fluid convection inside the undercooled melt. Theoretical calculation and electromagnetic levitation experiment have been used to investigate the internal velocity distribution and rapid solidification mechanism of Fe50Cu50 alloy. Based on axisymmetric electromagnetic levitation model, the distribution patterns of magnetic flux density and inducted current for levitated Fe50Cu50 alloy are calculated together with the mean Lorenz force. The Navier-Stokes equations are further taken into account in order to clarify the internal fluid flow. The results of the theoretical calculation reveal that the fluid velocity within levitated melt is strongly dependent on three factors, i.e., current density, current frequency and melt undercooling. As one of these factors increases, the maximum fluid velocity decreases while the average fluid velocity increases. Meanwhile, the area with fluid velocity larger than 100 mm·-1 is significantly extended. Furthermore, the fluid flow within levitated melt displays an annular tubular distribution characteristic. The Fe50Cu50 alloy melt is undercooled and solidified under electromagnetic levitation condition. In this undercooling regime △ T50Cu50 alloy melt has suppressed phase separation substantially. Once the undercooling attains a value of 150 K, metastable phase separation leads to the formation of layered pattern structure consisting of floating Fe-rich zone and sinking Cu-rich zone. A core-shell macrosegregation morphology with the Cu-rich zone distributed in the center and outside of the sample and Fe-rich zone in the middle occurs if the undercooling increases to 204 K. With the enhancement of undercooling after phase separation, the grain size of α -Fe dendrites in Cu-rich zone presents a decreasing trend. In contrast to the phase separated morphology of Fe50Cu50 alloy under the glass fluxing condition, the phase separated morphologies show obviously different characteristics. In such a case, the forced convection induced by electromagnetic stirring results in the formation of wavy interface between Fe-rich and Cu-rich zones, the distorted morphology of the Cu-rich spheres distributed in the Fe-rich zone, and the increased appearance probabilities of Cu-rich spheres at the upper part of electromagnetically levitated sample. Experimental observations demonstrate that the distribution pattern of Cu-rich spheres in Fe-rich zone is influenced by the tubular fluid flow inside the melt.
Research progress of imaging technologies based on electromagnetic metasurfaces
Authors: Fan Qing-Bin  , Xu Ting  ,   National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
Published: December 2020

Electromagnetic metamaterials are artificial structures engineered on a subwavelength scale to have optical properties that are not observed in their constituent materials and may not be found in nature either, such as negative refractive index. They have enabled unprecedented flexibility in manipulating light waves and producing various novel optical functionalities. Since the beginning of this century, with the development of nanofabrication and characterization technologies, there has been aroused a tremendous growing interest in the study of electromagnetic metamaterials and their potential applications in different fields including super-resolution imaging, optical biosensing, electromagnetic cloaking, photonic circuits and data storage. Electromagnetic metasurfaces are two-dimensional metamaterials composed of subwavelength planar building blocks. Although metasurfaces sacrifice some functionalities compared with their bulk counterparts, they provide us with distinct possibility to fully control light wave with ultrathin planar structures. Based on Huygens principle, the metasurfaces are able to arbitrarily manipulate the phases, amplitudes or polarizations of optical waves. For example, metasurfaces made of gold nanoantenna-arrays are able to create phase discontinuities for light propagating through the interfaces and drastically change the flows of reflected and refracted light at infrared frequencies. Comparing traditional dielectric optic elements, the thickness values of metasurface-based optical devices are much smaller. In addition to the control of free-space incident light, metasurfaces can also be used to precisely control and manipulate surface electromagnetic waves. In this review, we introduce the generalized Snell's law and the fundamental principles to modulate phase by using metasurfaces. Research progress of a variety of imaging technologies based on metasurfaces is then presented, including plasmonic metasurface, all-dielectric metasurface and metal/insulator hybrid metasurface. Finally, we summarize several frontier problems associated with metasurface, which maybe provide some references for the future researches and applications.
Single photon transport properties in the system of coupled cavity array nonlocally coupled to a -type three-level atom
Authors: Hai Lian  , Zhang Sha  , Li Wei-Yin  , Tan Lei  ,   School of Electrical and Information Engineering, North Minzu University, Yinchuan 750021, China;,   Key Laboratory of Physics and Photoelectric Information Functional Materials Sciences and Technology, North Minzu University, Yinchuan 750021, China;,   Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000, China
Published: December 2020

In this paper, we discuss the transport properties of a single photon, which is in a coupled cavity array system where the two nearest cavities nonlocally couple to a -type three-level atom, under the condition of ideal and dissipation, respectively. By employing the quasi-boson picture, the transmission amplitude of the single photon in an open system is investigated analytically. The system where the coupled cavity array nonlocally couples with the three-level atom demonstrates several advantages. Compared with other systems, this system has many parameters to manipulate the single photon transport properties. Moreover, the system of the coupled cavity array that nonlocally couples with the three-level atom may have a wider range of application because the single photon transmission spectrum in this system has three peaks. Furthermore, it has characteristics of its own. At the same value of Rabi frequency , changing the coupling strength between the atom and one cavity of the coupled cavity array shows that there exists an fixed point where the transmission rate is always 1, and the point is corresponding to the frequency of the photon c-. In the nonideal case, it is shown that the dissipations of the cavity and the atom affect distinctively the transmission of photons in the coupled cavity arrays. When considering only the dissipation of the atom, the atomic dissipation increases the dips of the single photon transport spectrum, while the peaks have no observable changes. When considering only the dissipation of the cavity, the peaks of the single photon transmission amplitude are diminished deeply, while the cavity dissipation does not have any effect on the dips. In addition, with both the cavity dissipation rate and the number of the cavity increasing, the photon transmission spectrum peaks decrease. A comparison of the dissipative cavity case with the dissipative atom case shows that the incomplete reflect near the peak is mostly caused by the cavity dissipation, and that the incomplete reflect near the dip is mostly caused by the three-level atom dissipation. Specifically, when considering both the atom and the cavity dissipation at the same time, the dips of the single photon transport spectrum are affected by both the atomic and the cavity dissipation. Instead, with the cavity dissipation rate increasing, the photon transmission spectrum dips are reduced. But for the peaks of the single photon transport spectrum, the dips are always determined by the cavity dissipation rate and the number of the cavity, while the atomic dissipation has no significant influence on them.
Generation of correlated pseudorandom varibales
Authors: Ma Xu-Bo  , Liu Jia-Yi  , Xu Jia-Yi  , Lu Fan  , Chen Yi-Xue  ,   School of Nuclear Science and Technolgy, North China Electric Power University, Beijing 102206, China
Published: December 2020

When Monte Carlo method is used to study many problems, it is sometimes necessary to sample correlated pseudorandom variables. Previous studies have shown that the Cholesky decomposition method can be used to generate correlated pseudorandom variables when the covariance matrix satisfies the positive eigenvalue condition. However, some covariance matrices do not satisfy the condition. In this study, the theoretical formula for generating correlated pseudorandom variables is deduced, and it is found that Cholesky decomposition is not the only way to generate multidimensional correlated pseudorandom variables. The other matrix decomposition methods can be used to generate multidimensional relevant random variables if the positive eigenvalue condition is satisfied. At the same time, we give the formula for generating the multidimensional random variable by using the covariance matrix, the relative covariance matrix and the correlation coefficient matrix to facilitate the later use. In order to verify the above theory, a simple test example with 33 relative covariance matrix is used, and it is found that the correlation coefficient results obtained by Jacobi method are consistent with those from the Cholesky method. The correlation coefficients are more close to the real values with increasing the sampling number. After that, the antineutrino energy spectra of Daya Bay are generated by using Jacobi matrix decomposition and Cholesky matrix decomposition method, and their relative errors of each energy bin are in good agreement, and the differences are less than 5.0% in almost all the energy bins. The above two tests demonstrate that the theoretical formula for generating correlated pseudorandom variables is corrected. Generating correlated pseudorandom variables is used in nuclear energy to analyze the uncertainty of nuclear data library in reactor simulation, and many codes have been developed, such as one-, two-and three-dimensional TSUNAMI, SCALE-SS, XSUSA, and SUACL. However, when the method of generating correlated pseudorandom variables is used to decompose the 238U radiation cross section covariance matrix, it is found that the negative eigenvalue appears and previous study method cannot be used. In order to deal with the 238U radiation cross section covariance matrix and other similar matrices, the zero correction is proposed. When the zero correction is used in Cholesky diagonal correction and Jacobi eigenvalue zero correction, it is found that Jacobi negative eigenvalue zero correction error is smaller than that with Cholesky diagonal correction. In future, the theory about zero correction will be studied and it will focus on ascertaining which correction method is better for the negative eigenvalue matrix.
Majorana representation for the nonlinear two-mode boson system
Authors: Fang Jie  , Han Dong-Mei  , Liu Hui  , Liu Hao-Di  , Zheng Tai-Yu  ,   Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130024, China
Published: December 2020

By presenting the quantum evolution with the trajectories of points on the Bloch sphere, the Majorana representation provides an intuitive way to study a high dimensional quantum evolution. In this work, we study the dynamical evolution of the nonlinear two-mode boson system both in the mean-field model by one point on the Bloch sphere and the second-quantized model by the Majorana points, respectively. It is shown that the evolution of the state in the mean-field model and the self-trapping effect can be perfectly characterized by the motion of the point, while the quantum evolution in the second-quantized model can be expressed by an elegant formula of the Majorana points. We find that the motions of states in the two models are the same in linear case. In the nonlinear case, the contribution of the boson interactions to the formula of Majorana points in the second quantized model can be decomposed into two parts:one is the single point part which equals to the nonlinear part of the equation in mean-field model under lager boson number limit; the other one is related to the correlations between the Majorana points which cannot be found in the equation of the point in mean-field model. This means that, the quantum fluctuation which is neglected in the mean-field model can be represented by these correlations. To illustrate our results and shed more light on these two different models, we discussed the quantum state evolution and corresponding self-trapping phenomenon with different boson numbers and boson interacting strength by using the fidelity between the states of the two models and the correlation between the Majoranapoints and the single points in the mean-field model. The result show that the dynamics evolution of the two models are quite different with small boson numbers, since the correlation between the Majorana stars cannot be neglected. However, the second-quantized evolution and the mean-field evolution still vary in both the fidelity population difference between the two boson modes and the fidelity of the states in the two models. The difference between the continuous changes of the second quantized evolution with the boson interacting strength and the critical behavior of the mean-field evolution which related to the self-trapping effect is also discussed. These results can help us to investigate how to include the quantum fluctuation into the mean-field model and find a method beyond the mean field approach.
Influences of BaO doping on the properties of single domain GdBCO bulk superconductors (II)
Authors: Wang Miao  , Wu Hua-Chun  , Yang Wan-Min  , Yang Peng-Tao  , Wang Xiao-Mei  , Hao Da-Peng  , Dang Wen-Jia  , Zhang Ming  , Hu Cheng-Xi  ,   School of Science, Xi'an Aeronautical University, Xi'an 710077, China;,   School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

In order to inhibit the Gd/Ba substitution in the growth process effectively, a series of single domain GdBCO bulk superconductors with different ratios of BaO additions in the solid phase pellet is successfully fabricated by the modified top seeded infiltration growth technique on the basis of previous research. In the present work, the macroscopic feature, microstructure and critical current density (Jc) of the single domain GdBCO bulk superconductor are investigated in detail. From the top view of the surface of the single domain GdBCO bulk superconductor, all of the samples exhibit clearly the fourfold growth sector boundaries on their top surfaces, and spontaneous satellite grains are observed in none of these samples. It can be seen that the different ratio of BaO addition (from 1 wt% to 4 wt%) cannot affect the growth morphology of the single domain GdBCO bulk superconductor. At the same time, for observations of the microstructure, the small test specimens of dimensions about 2 mm2 mm2 mm are cut from the top surface of the singe domain GdBCO bulk superconductors with different BaO doping ratios and at a distance 5 mm away from the seed, then microstructure analysis is performed in the cleavage phane of the test specimen by using scanning electron microscope. For the sample with 1 wt% BaO doping, the derivative phase of GdBCO (Gd123ss) is found in the Gd123 superconducting matrix. To detect the atomic ratio of the Gd123ss, energy dispersive X-ray spectrometry measurement is carried out on the samples. It is shown that the atomic ratio of the Gd123ss phase is Gd:Ba:Cu=1.566:1.459:3, which proves successfully that the Gd123ss is a kind of phase with lack of barium. With the increase of BaO doping, the phenomenon of lack of barium is effectively controlled and, the nano Gd123ss phase is generated as the flux pinning centre which can be used to improve the superconducting properties in the growth process of GdBCO bulk superconductor. This results can be concluded that the proper doping ratio can control the element substitution effectively, and the solid solution phase can be greatly reduced to some extent, and the critical current can be improved to a certain extent when the amount of BaO added ranges from 2 wt% to 4 wt%, which is very helpful in inhibiting the Gd/Ba substitution and fabricating the high-quality single domain GdBCO bulk superconductors.
Enthalpy relaxation studies of memory effect in various glass formers in the vicinity of glass transition
Authors: Jin Xiao  , Wang Li-Min  ,   State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

The glass is in a non-equilibrium state in nature, and relaxation might occur towards the equilibrium state at a certain temperature. When heating a quenched glass, relaxation can be resolved as temperature approaches to the glass transition, and further heating leads to enthalpy recovery as the system turns into an equilibrium supercooled liquid. The released energy involving the relaxation relative to the original quenched state is, in magnitude, identical to the gained energy in enthalpy recovery, showing a memory effect. In this paper, we discuss the enthalpy behaviors involved in a cooling and reheating cycle around the glass transition in various glass forming systems such as oxides, metal alloys, and small molecular systems. The cooling and heating rates are fixed to be -/+ 20 K/min with the related cooling and heating heat capacity curves being determined. It is found that the relaxation enthalpy involved in the cooling/heating cycles is closely related to the enthalpy of fusion for the glass forming materials, and the basically linear correlation implies the similarity between the glass transition and melting behaviors with regard to the atomic rearrangements involved in the relaxation and solidification processes. The determining of the cooling and heating heat capacity curves also helps establish the enthalpy relaxation/recovery spectra of various glasses, and the symmetry of the spectrum is associated with the fragility of glass-forming material. For the material of low or medium fragilities, the symmetry of the enthalpy relaxation spectrum is observed to be somehow dependent on the fragility, while for the high fragility glass, the symmetry keeps almost constant. The dependence of fragility on the glass transition thermodynamics is also discussed, and low melting entropy and high fragility are shown to reduce effectively the liquid-crystal Gibbs free energy difference. Using the correlation between the relaxation enthalpy and kinetic fragility reported in our previous studies, the glass transition thermodynamics for the case of the most fragile glass with m= 175 is evaluated, especially compared with the second phase transition of thermodynamics. The results provide a new understanding of the thermodynamics of the relaxation in glassy material and the glass transition.
Research progress of metallic plastic
Authors: Zhang Bo  , Wang Wei-Hua  ,   School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Metallic plastic, named and developed by Chinese scientists, is a kind of new material. Here in this paper we explain how this material was discovered and its design philosophy and principle. The chemical compositions, micro-structures, and typical physical and chemical properties of these metallic plastic materials are summarized in this paper. The potential applications of the metallic plastic materials are also analyzed.
Self-organized critical behavior in plastic flow of amorphous solids
Authors: Sun Bao-An  , Wang Li-Feng  , Shao Jian-Hua  ,   Herbert Gleiter Institute For Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Amorphous solids are metastable materials formed by the rapid quenching of liquid melts. Under mechanical stress, amorphous solid displays unique and complex plastic flow behavior, which is both spatially and temporally inhomogeneous on different length scales. In some cases, the plastic flow behavior of amorphous solid can evolve into the self-organized critical state, which is similar to many complex phenomena in nature and physics such as earthquakes, snow avelanches, motions of magnetic walls, etc. In this paper, we briefly review the recent research progress of the plastic flows of amorphous solids, with an emphasis on the plastic flow of metallic glass which has been one of our research foci in past few years. The review begins with an introduction of the inhomogeneous flow behaviors on different scales, from the macroscopical-scale spatially inhomogeous shear bands, temporally intermittent serrated flow to the atomic-scale localized viscoelastic behavior in metallic glass. The microscopical deformation theories including free volume model and shear transformation zone model, and recent efforts to elucidate macrosopical flow behaviors with these theories, are also presented. Finally, recent progress of the self-organized critical (SOC) behaviors of the plastic flow of metallic glass are reviewed, with an emphasis on its experimental characterizations and the underlying physics. The emergence of SOC in the plastic flow is closely related to the interactions between plastic flow carriers, and based on this point, the relation between the SOC behavior and the plasticity of metallic glass is elucidated. The implications of plastic flow of metallic glass for understanding the occurence of earthquakes are also discussed. The review is also concluded with some perspertives and unsolved issues for the plastic flow of amorphous solids.
Cluster state based controlled quantum secure direct communication protocol with controllable channel capacity
Authors: Zheng Xiao-Yi  , Long Yin-Xiang  ,   Automation Engineering Department, Guangdong Technical College of Water Resource and Electric Engineering, Guangzhou 510635, China
Published: December 2020

Controllable quantum secure direct communication is an important branch of quantum communication. In this paper, we propose a controlled quantum secure direct communication protocol with channel capacity controllable based on a five-particle cluster state. To start with, the sender Alice prepares the five-particle cluster state sequence and inserts decoy photon randomly, and then sends two parts of the particle sequence to the receiver Bob and the controller Cindy, and meanwhile keeps one part of the particle sequence himself. After Bob and Cindy receive the particle sequence, Alice performs a Z-based single-particle measurement and publishes the measurement results and the position information of the decoy photon through the classical channel. According to the information published by Alice, Bob and Cindy remove the decoy photon and perform a Bell-state measurement to their own part particle sequence. Three sides of communication complete the first safety examination of the channel by checking the bit error rate of the measurement results. After that, the controller Cindy determines the channel capacity by selecting the measurement base (Z basis or X basis) to measure its own particle sequence, and then announces the measured results with classical channel. The sender Alice inserts decoy photon and codes the information by doing a unitary transformation to its own particle sequence and then sends the receiver Bob and tells him the position information of the decoy photon with classical channel. Combining the information published by Cindy with the information transmitted by Alice, Bob can complete the second safety examination of the channel and decode the information Alice has sent by removing decoy photon and performing a Bell-state measurement of his own two groups of particle with appropriate rules. Through an analysis of the entangled structural properties of the five-particle cluster state, it has been confirmed that this protocol is designed to make full use of the entanglement properties of the five-particle cluster in different entangled structures. Therefore the protocol can obviously be generalized into the two-way controlled quantum secure direct communication by simply changing the rules of the measurement and the particles used for unitary coding. Through analyzing the security of this protocol, it reveals that this protocol can effectively both prevent eavesdroppers from eavesdropping useful information and monitor this kind of act, and therefore the controlled quantum secure direct communication can theoretically be established in a certain noise environment.
A broadband polarization converter based on resonant ring in terahertz region
Authors: Fu Ya-Nan  , Zhang Xin-Qun  , Zhao Guo-Zhong  , Li Yong-Hua  , Yu Jia-Yi  ,   Department of Physics, Capital Normal University, Beijing 100048, China;,   Beijing Advanced Innovation Center for Imaging Technology, Beijing 100048, China;,   Key Laboratory of THz Optoelectronics, Ministry of Education, Beijing 100048, China
Published: December 2020

The terahertz polarization converter has potential applications in the field of terahertz spectroscopy and imaging. A broadband and high conversion rate of terahertz linear polarization converter based on the metasurface of resonant ring is proposed. The designed structure consists of three layers, i.e., the top layer, which is a metasurface of resonant ring; the bottom layer, which is a metal film of aluminum; a dielectric layer of polyethylene terephthalate, which is sandwiched in between. In order to obtain the best performance, the simulation and optimization are performed by using CST microwave studio. At the same time, the preparation conditions are also taken into account. The optimized geometric parameters of device are obtained. The samples are prepared by using the photolithography and wet etching. The performance of the designed polarization converter is demonstrated experimentally by using the terahertz time domain spectroscopy. The experimental results show that the proposed device can rotate 90° the polarization state of incident terahertz wave of linear polarization in a frequency range from 0.59 THz to 1.24 THz. The polarization conversion rate is more than 80%. The experimental result is in good agreement with the simulated one. By calculating the polarization angle and elliptical angle of the reflected terahertz wave, it is proved that this device can achieve a high-efficiency linear polarization conversion in a wide frequency range. The distributions of surface currents and electric fields are simulated at the frequency with the high polarization conversion rate. The mechanism of high polarization conversion rate is analyzed based on the distribution of surface currents. The performances of broadband and high conversion rate of the designed structure are derived from the third-order electromagnetic resonance. At the same time, the dependence of the polarization conversion rate on incident angle and polarization angle is stimulated and analyzed. The results show that this device has a good polarization conversion performance in an incidence angle range of 0°-30° and a polarization angle range of-10°-10°.