bluuebunny/crossref_metadata_2025 huggingface dataset:
Vides i successos de quatre monjos de Sant Jeroni de Cotalba
Authors: Galera Rubén
Published: December 2020

Resum: El monestir de Sant Jeroni de Cotalba és una de les grans obres que va dur a terme el duc de Gandia, Alfons el Vell, a les darreries del segle xiv. Encara que el van fundar dotze monjos portats de la Plana de Xàbia, paulatinament van engrossir el nombre de religiosos que podia albergar, fins arribar-ne a quaranta. Un d’aquells monjos, que era arxiver, tenia cura de deixar per escrit les efemèrides més memorables dels avatars del monestir i dels seus religiosos. Amb el temps, això serví perquè els historiadors de l’Orde, com ara José Sigüenza, demanaren a cada monestir les dades més rellevants de la fundació i dels benefactors, però sobretot de les vides exemplars dels monjos. Per sort, el pare Francesc del Castillo, arquer i arxiver de Cotalba a la meitat del segle xviii, tingué la informació suficient per escriure la seua Historia del Real Monasterio de Sant Jerónimo de Gandía o de Cotalva. L’objectiu d’aquest article és, per tant, donar a conèixer només les vides excepcionals dels monjos de Cotalba que, dins la vida monàstica, van presenciar fets d’ultratomba, sanaren malalts crònics amb la fe i predicaren durant setmanes amb molt poques hores de descans.Paraules clau: Sant Jeroni de Cotalba, Francesc del Castillo, crònica, vides exemplars de monjosAbstract: The monastery of Sant Jeroni de Cotalba is one of the great works that the duke of Gandia, Alfons el Vell, carried out in the xiv century. Although it was founded by twelve monks brought from the Plana de Xàbia, gradually they increased the number of religious that it could host, in order to arrive at forty. One of those monks, who was an archivist, took care of leaving in writing most memorable ephemerides of the vicissitudes of the monastery and of their monks. Over time, that served for the historians of the Order, as José Sigüenza, to require every monastery the most relevant data of the foundation and the benefactors, but above all the exemplary lives of the monks. Luckily, Francesc del Castillo, accoutant and archivist of Cotalba in the middle of the 18th century, had enough information to write his Historia del Real Monasterio de Sant Jerónimo de Gandía o de Cotalva. The objective of this article is so to make known only the exceptional lives of the monks of Cotalba who, within the monastic life, they witnessed beyond the grave events, healed the chronic ill by faith and preached for weeks with very few hours of rest.Keywords: Sant Jeroni de Cotalba, Francesc del Castillo, chronicle, exemplary lives of monks
Violencia conyugal y víctimas de la guerra: la valenciana Beatriz Martí y la troyana Andrómaca de Eurípides
Authors: Terzopoulou Anastasia
Published: December 2020

Resumen: En este trabajo se desarrolla el tema de la violencia de la mujer en la Antigua Grecia y en la Corona de Aragón a finales de la Edad Media. Concretamente, los casos que se analizan tienen que ver, por una parte, con la violencia cometida contra la princesa de Troya, Andrómaca, la cual tras el saqueo y la caída de su patria se ha convertido en una cautiva de guerra, en una concubina de la familia que mató a su esposo e hijo; y, por la otra, con la violencia marital de la valenciana Beatriz Martí. Ambas mujeres, a pesar de los siglos que les separan, sufren injusticias y dolor, pero, también cuentan con una persona que les presta su ayuda y protección: en el caso de Andrómaca es Peleo, el abuelo de su actual amo; y, en el caso de Beatriz, la reina María de Aragón. Palabras clave: mujer, violencia, protección, maltrato, defensa Abstract: This paper develops the issue of violence against women in Ancient Greece and in the Crown of Aragon in the Late Middle Ages. Specifically, the cases analyzed have to do, on the one hand, with the violence committed against the Princess of Troy, Andromache, who, after the looting and fall of her homeland, has become a war captive, a concubine of the family that killed her husband and son; and, on the other, the case of the marital violence of the Valencian Beatriz Martí. Both women, despite the centuries that separate them, suffer injustices and pain, but they also have a person who helps and protects them: in the case of Andromache it is Peleus, the grandfather of its current owner; and, in the case of Beatriz, Queen Maria of Aragon.Keywords: woman, violence, protection, abuse, defense
La violència física i econòmica contra les dones a la Mallorca del segle XVII: una aproximació
Authors: Bauçà Nicolau Victòria
Published: December 2020

Resum: En aquesta primera aproximació a la Mallorca del segle XVII, es pot veure com les dones patien diferents tipus de violència. Per una banda, la física, que era exercida tant per part de desconeguts com per part dels marits dins de l’entorn conjugal. La fugida de la maltractada era la solució més habitual i, en moltes ocasions, la disputa acaba amb divorci. per altra banda, s’ha documentat l’existència d’una violència que es pot denominar econòmica i que es basa en l’exclusió de la dona de les seves pròpies possessions, cosa que conduïa a llargs litigis per a la restitució dotal o per a reclamar una herència. Generalment, aquesta violència es donava quan les dones quedaven soles i en situació de vulnerabilitat econòmica i social, i era exercida, de manera habitual, per homes propers a elles de diferents modes. Així i tot, es comprova el tarannà reivindicatiu i actiu de les dones mallorquines davant aquests tipus de violències.Paraules clau: violència, maltractament, dona, dot, herènciaAbstract: In this first approach to Mallorca in the seventeenth century, we can see how women suffered different types of violence. On the one hand, the physical violence was exercised both by strangers and by husbands within the conjugal environment. The most common solution to this violence was the escape of the woman who was being abused. In many cases, the dispute ended in divorce. On the other hand, we documented the existence of violence that can be called economic. This type of violence is based on the exclusion of women from their own possessions, which led to lengthy litigation for dowry restitution or to claim an inheritance. Generally, this violence occurred when women were left alone and in a situation of economic and social vulnerability. The economic violence was usually exercised by men close to the victims in different ways. However, we can highlight the vindictive and active disposition of Mallorcan women in the face of these types of violences.Keywords: violence, maltreatment, woman, dowry, inheritance
Dona, pobra, mare i fadrina contra l’autoritat moral. El procés inquisitorial d’Àgueda Guimerà (1804)
Authors: Mompó Navarro Jacob
Published: December 2020

Resum: En 1804, el Tribunal de la Inquisició vivia els seus darrers moments. Lluny de les grans persecucions inicials contra jueus i moriscos, el Sant Ofici semblava llanguir, però sense dubte, tot i que amb menys força que en temps passats, encara era un instrument formidable de repressió. En aquest context, Àgueda Guimerà, mare soltera, i per això criticada i maltractada, va haver de fer front a una denúncia per calúmnies per part del seu confessor en què en tot moment plana la sospita del delicte de sol·licitació en acte de confessióParaules clau: Inquisició, conducta moral, dona soltera, segle XIX, sol·licitacióAbstract: In 1804, the Court of the Inquisition was living its last moments. Far from the great initial persecutions against Jews and Moors, the Holy Office seemed to languish, but certainly, although with less force than in past times, still was a formidable instrument of repression. In this context, Àgueda Guimerà, a single mother, and therefore criticized and mistreated, had to face a denunciation for slander by her confessor in which the suspicion of the crime of solicitation in the act of confession was floating in the air.Keywords: Inquisition, moral conduct, single woman, nineteenth century, solicitation
Trovatori catalani e unità aquitana
Authors: Viel Riccardo
Published: December 2020

Riassunto: l saggio analizza i rapporti tra la produzione poetica dei trovatori aquitani e calatani in occitano del XII secolo, in particolare tra Guglielmo IX d’Aquitania, Marcoat e Marcabru. In questa prospettiva il mio saggio ha lo scopo di ricostruire il quadro delle relazioni storiche e linguistiche tra il mondo catalano, la Provenza e il Poitou, con una verifica sulle fonti manoscritte.Parole chiave: trovatori catalani, Aquitania, letteratura medioevaleAbstract: The article will analyze the relationship existing between the lyric production of aquitaine and catalan Troubadours, with particular regard to Williams IX duke of Aquitaine, Marcoat and Marcabru. The study aims furthermore at reconstructing an outline of historical and linguistic relationships between Catalonia, Provence and Poitou with a survey of the manuscript sources.Keywords: Catalan troubadours, Aquitaine, medieval literature
LA BAHÍA QUE ILUMINÓ A DARWIN
Authors: Farinati Esther Amanda , Manera Teresa , Tomassini Rodrigo L
Published: December 2020

Los últimos estudios sobre los hallazgos y observaciones que Darwin hiciera durante su viaje a bordo del Beagle señalan al área de Bahía Blanca, en el sudoeste de la región pampeana como una de las escalas más inspiradoras para la elaboración de su teoría de la evolución. Los sitios de Punta Alta y Monte Hermoso con sus restos fósiles de mamíferos cenozoicos fueron una de las mayores motivaciones del joven naturalista. Las exploraciones paleontológicas junto a las observaciones que realizara sobre la fauna y la flora de la región constituyen la evidencia de que esta zona fue un componente crucial para su pensamiento transmutacional aunque los historiadores lo hayan pasado por alto o minimizado.
RECENSIÓN. The paleobiological revolution. Essays on the growth of modern Paleontology
Authors: Aguirre Julio
Published: December 2020

The paleobiological revolution. Essays on the growth of modern Paleontology es un libro de nombres propios escrito por los propios personajes que cimentaron y construyeronel andimahe sobre el que se sustenta el propio edificio de la Paleobiología de las últimas décadas. A todas luces, es un libro de historia reciente cuya lectura recomiendo encarecidamente. Tras su lector no queda ninguna duda del papel que juega la Paleobiología en evolución pero, al mismo tiempo, nos enseña que aún queda mucho por hacer en lo que al acercamiento entre Biología y Paleontología se refiere. Quizás, pensar en la visión integradora de Jaekel y su Biontología con ideas renovadas y actualizadas podría servir de gran lección para todos los que de alguna manera trabajamos reconstruyendo la evolución del mundo orgánico.
DIVERSIDAD Y EVOLUCIÓN DE LA TEXTURA DE LA PARED EN GUEMBELÍTRIDOS (FORAMINÍFEROS PLANCTÓNICOS) DEL TRÁNSITO CRETÁCICO-PALEÓGENO
Authors: Arenillas Ignacio , Arz José Antonio , Náñez Carolina
Published: December 2020

Un análisis detallado de los guembelítridos (Guembelitria, Palaeoglobigerina, Parvularugoglobigerina, Chiloguembelitria?, Woodringina, Postrugoglobigerina? y Globoconusa) del tránsito Cretácico-Paleógeno (K-Pg) indica una alta variabilidad y diversidad en sus texturas de pared, lo que puede tener importantes implicaciones taxonómicas y filogenéticas. Se han reconocido doce texturas de pared, cuatro de ellas en el Maastrichtiense terminal y al menos diez en el Daniense basal. La textura de pared con poros en túmulo, que predominó durante el Maastrichtiense terminal, desapareció progresivamente tras el límite K/Pg, mientras que una diversificación en el Daniense basal dio origen a texturas de pared lisas, rugosas y finalmente pustuladas.
IN MEMORIAM DE NIEVES LÓPEZ MARTÍNEZ
Authors: Álvarez Sierra Marián , Delgado Ángela
Published: December 2020

Nieves trabajó en todos los campos de la Paleontología: Taxonomía, Sistemática, Tafonomía, Evolución, Paleobiogeografía, Biocronología, Bioestratigrafía. Su Curriculum Vitae es verdaderamente impresionante. Dirigió numerosos proyectos de investigación del Plan Nacional, diez Tesis Doctorales, más de veinte Tesinas, Diplomas de Estudios Avanzados y Tesis de Máster, publicó cerca de 200 artículos científicos y libros, y dirigía el grupo de Investigación de la UCM “Registro geológico de periodos críticos: factores paleoclimáticos y paleoambientales”. Durante años lideró el proyecto de excavación de Somosaguas. Ella fue la promotora y el alma del Doctorado, con mención de calidad, Interuniversitario de Paleontología en el que estaban implicadas tres de las Universidades públicas de Madrid (UCM, UAM y UAH). Divulgó la Paleontología en todos los ámbitos y lugares, de forma especial en su amado Pirineo.
Nieves López ha sido un referente para todos aquellos que creen en la razón, en la justicia, a los que aman la naturaleza y que como naturalistas han perseguido comprender la vida. Puso la primera piedra en el Departamento de Biología de la Autónoma de Madrid, y ahí es donde han crecido ya cinco generaciones de paleontólogos.
Energy balance and robustness adjustable topology control algorithm for wireless sensor networks
Authors: Hao Xiao-Chen  , Liu Wei-Jing  , Xin Min-Jie  , Yao Ning  , Ru Xiao-Yue  ,   School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

In wireless sensor networks, the interference around the application environment may cause the actual distance between any pair of nodes to fail to be measured accurately. Enclosure graph (EG) model uses this distance between nodes as its weight to construct the topology, which does not fully consider the interference. Consequently it will lead to a large amount of energy consumption induced by the application environment. Even it shortens the survival time. According to the feature of network energy inequality in a wireless sensor network and the defect of EG, we first introduce the adjustable factor of node degree, establish a model of communication metric and a model for the node actual survival time. Then according to the demand of network energy equalization and maximum network lifetime, we quantitatively analyze the network node degree, and achieve its regular pattern. In accordance with this regular pattern and sufficient conditions of function extremum, the maximum node energy consumption and the maximum node actual survival time are deduced. And the corresponding optimal node degree is achieved. Finally, according to the above model, in this paper we propose an energy balance and robustness adjustable topology control algorithm for wireless sensor networks. Theoretical analyses show that this algorithm can guarantee that the network is connected and the link of the network is bi-directionally connected. Experiments show that the network takes advantage of this optimal node degree to obtain the high robustness, thus guaranteeing that the information can be transferred unfailingly. This algorithm can effectively balance the node energy, improve the node survival time, enhance the network robustness, and prolong the network's lifetime.
Molecular dynamics simulation of the thermophysical properties and phase change behaviors of aluminum nanoparticles
Authors: Lin Chang-Peng  , Liu Xin-Jian  , Rao Zhong-Hao  ,   School of Electric Power Engineering, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

With the development of energy storage technology, phase change materials which can be used to store thermal energy have received much attention in recent years. The nano-metallic materials are universally used as phase change materials due to their many desirable thermophysical properites. In this paper, the molecular dynamics simulation method is adopted to simulate the variations of melting point, density and phonon thermal conductivity of the nano aluminum with grain size ranging from 0.8 nm to 3.2 nm. The variations of density, specific heat capacity and phonon thermal conductivity with temperature of aluminum nanoparticles at a grain size of 1.6 nm are also studied. By using the embedded-atom potential, the thermophysical properties and phase change behaviors of aluminum nanoparticles are stimulated. The phase transition temperature of aluminum nanoparticles is studied based on the energy-temperature curve and the specific heat capacity-temperature curve. The surface energy theory and the size effect theory are applied to the analysis of the variation of the melting point of the aluminum nanoparticles, and the results show that the melting point increases as grain size augments, and it increases slowly when its grain size is between 2.2 nm and 3.2 nm but still holds the trend of increase. In order to obtain accurate thermal conductivity, the Green-Kubo method is adopted to calculate the phonon thermal conductivity of aluminum nanoparticle. As the grain size of aluminum nanoparticles increases, its density monotonically decreases, and the thermal conductivity monotonically increases linearly, which is in line with the theory of phonon. Similarly, with the increase of temperature, the density and thermal conductivity of aluminum nanoparticles of 1.6 nm in grain size both decrease. Moreover, the density of aluminum nanoparticle is generally lower than that of its bulk material. The study also shows that the heat transfer manner of aluminum nanoparticle is based on ballistic-diffusive heat conduction instead of the traditional diffusive heat conduction when it is in a nanoscale. The simulation studies the thermophysical properties of nanoparticles from the atomic perspective, and is of significance for guiding the design of the phase change materials based on the aluminum nanoparticles for thermal energy storage.
Reconstruction and calibration on aero-optical wavefront aberration based on Background oriented schlieren based wavefront sensing
Authors: Zhang Tian-Tian  , Yi Shi-He  , Zhu Yang-Zhu  , He Lin  ,   College of Aerospace Science and Engineeriing, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Background oriented schlieren based wavefront sensing (BOS-WS) is a new experimental technique for measuring the two-dimensional distribution of optical wavefronts and the optical path differences (OPDs) induced by the flow-field density variations. Background oriented schlieren (BOS) is traditionally used to test the flow-field density distribution, which restricts the obtaining of useful information since the obtained density information is integrated over the optical path. The OPD is very important for predicting the optical distortion when light travels through the flow field and it is tested by BOS-WS. In order to obtain the optical distortion generated by aero-optic effect, and restore the original image from the distortion known information so as to explore a new kind of supersonic imaging guidance method, theory analysis, numerical simulation and experimental methods are used based on BOS-WS. Through theoretical analysis, the wavefront measurement method based on BOS is verified and the calculation methods of using wavefront information known to predict distortion displacement field and using known displacement field to reconstruct wavefront are explored. By numerical simulation, the error sizes and the result rationalities of one stepped integral algorithm and Southwell method on the wavefront reconstruction are compared, and through the error analysis it is proved that the Southwell method is more accurate and reasonable. By a wavefront aberration experiment carried out in the flow field above the candle flame and a lens perturbation experiment, the methods of using OPD known to reconstruct distorted displacement field and correcting image distortion by the field are creatively explored. The verification experiments show the effectiveness of the correction method.
Effects of growth conditions on the microstructures and photoluminescence properties of Ga-doped ZnO films
Authors: Zhou Xiao-Hong  , Yang Qing  , Zou Jun-Tao  , Liang Shu-Hua  ,   Faculty of Materials Science and Engineering, Xi'an University of Technology, Xi'an 710048, China;,   Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology, Xi'an University of Technology, Xi'an 710048, China
Published: December 2020

ZnO has a wide direct band gap of 3.37 eV and a large exciton binding energy of 60 meV at room temperature, which is recognized as one of the promising semiconductors for optoelectronic device applications. However, ZnO generally displays visible defect-related deep-level emission and/or UV near-band-edge emission, which is strongly dependent on the growth method and condition. It has been reported that doping with IIIA elements can improve the optical properties of ZnO. Among them, Ga doping is considered not to induce large lattice distortion of ZnO due to the fact that the bonding lengths of Ga-O and Zn-O are similar and ionic radii of Ga3+ and Zn2+ are also similar. The gallium related compounds such as triethylgallium, gallium nitrate and gallium oxide are used as the Ga doping sources. It has been proved that ZnO film can be grown directly by the thermal oxidation of ZnS substrate. In this research, the Ga doping is adopted in the growth of ZnO film by applying the molten gallium to the surface of ZnS substrate and performing the subsequent thermal oxidation in the air at 650 and 700 °C for 3 and 8 h, respectively. The effects of growth condition on the microstructures and photoluminescence properties of the Ga-doped ZnO film are investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and photoluminescence at room temperature. In addition, the relationship among the oxidation temperature, oxidation time, Ga doping content and photoluminescence properties is discussed. The results show that the Ga-doped ZnO films grown under different growth conditions exhibit various amounts of Ga content and the gallium is present in the ZnO matrix as Ga3+ by partially substituting Zn2+. The Ga doping affects the microstructure and photoluminescence property by changing the defect type and level, stoichiometric ratio, and crystal quality of ZnO film. As the oxidation temperature increases, the amount of Ga doping content increases. In addition, the grain size of the Ga-doped ZnO film increases and becomes uniform, and the ratio of ultraviolet emission intensity to visible emission intensity increases. However, as the oxidation time increases, the amount of Ga doping content decreases, the grain size of the Ga-doped ZnO film becomes non-uniform, and the ratio of ultraviolet emission intensity to visible emission intensity decreases.
Isoelectronic traps and thermoluminescence characteristics in MSO4:Eu2+ (M =Mg, Ca, Sr, Ba)
Authors: Luo Da-Ling  , Tang Qiang  , Guo Jing-Yuan  , Zhang Chun-Xiang  ,   School of Physics Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Published: December 2020

A series of alkaline earth sulphate phosphors MSO4:Eu2+ (M =Mg, Ca, Sr, Ba) is obtained in doping experiments. It is discovered that these phosphors doped with Eu2+ ions have the thermoluminescence (TL) characteristics which are quite different from those in the alkaline earth sulphate phosphors doped with trivalent rare earth ions RE3+ (RE= Dy, Tm, Eu). It is also observed that there is only one glow peak in the three-dimensional emission spectrum and the radiation dose response of the glow peak is linear-sublinear in the series of phosphors MSO4:Eu2+ (M =Mg, Ca, Sr, Ba). However, quite a lot of experimental results show that there are several glow peaks in the three-dimensional emission spectrum, and the TL radiation dose responses are linear-supralinear in the series of phosphors MSO4:RE3+ (M =Mg, Ca, Sr, Ba and RE= Dy, Tm, Eu). The reason lies in the structures of defect complexes which are formed in the course of preparation of these phosphors and include intrinsic imperfects and dopants. These defect complexes can be regarded as basic elements in the TL multi-stage process. In the series of phosphors MSO4:Eu2+ (M =Mg, Ca, Sr, Ba), the isoelectronic traps produced by doping Eu2+ ions which have the same valences as superseded alkaline earth ions are very localized traps to form the defect complexes (Eu2+ isoelectronic trap-SO42-) that are basic elements in the TL multi-stage process, in which there are one-hit TL events basically. However, in the MSO4:RE3+ (M =Mg, Ca, Sr, Ba) phosphors, the defect complexes (RE3+-SO42--cation vacancy VM) are basic elements in the TL multi-stage process, in which there are two-hit TL events basically. It is clear that the Eu2+ isoelectronic trap phosphors play key roles in TL Characteristics in MSO4:Eu2+ (M = Mg, Ca, Sr, Ba). In addition, it has been observed that the wave length at the single TL peak in each of the three-dimensional emission spectra of the series of phosphors MSO4:Eu2+ (M =Mg, Ca, Sr, Ba) is related to the substrate of each of these phosphors, such as the wave lengths at the TL peaks are 440, 385, 375 and 375 nm for MgSO4:Eu2+, CaSO4:Eu2+, SrSO4:Eu2+, and BaSO4:Eu2+ respectively. The experimental results display the characteristics of Eu2+ isoelectronic traps formed by substituting alkaline earth ions which have different cationic radii and electronegativities. The SrSO4:Eu2+ phosphor can be called typical isoelectronic trap phosphor which has the higher TL and optical stimulated luminescence efficiency.
Preparation and exchange bias effects of Bi0.8Ba0.2FeO3/La0.7Sr0.3MnO3 heterostructures
Authors: Wei Ji-Zhou  , Zhang Ming  , Deng Hao-Liang  , Chu Shang-Jie  , Du Min-Yong  , Yan Hui  ,   College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China;,   School of Science, Tianjin University of Technology and Education, Tianjin 300222, China
Published: December 2020

Bi0.8Ba0.2FeO3/La0.7Sr0.3MnO3 multiferroic heterostructures are successfully synthesized on single crystal LaAlO3(100) substrates by pulsed laser deposition via adjusting the parameters of laser energy, laser frequency, substrate temperature, oxygen pressure, distance between substrate and target, etc. The pure phase with perovskite structure is confirmed by the X-ray diffraction measurements. Using high-resolution transmission electron microscopy and energy dispersive X-Ray spectroscopy, we find that all the layers show preferential (00l) orientation, suggesting the epitaxial growth of the multilayered structure. Isothermal (7 K) M-H curves measured on sample after cooling the sample down to lower than ± 1 T fields reveal a shift in M-H loop. The strong temperature dependence of HEB is likely to be directly related to an electronic orbital reconstruction at the interface and complex interplay between orbital and spin degrees of freedom.
Transfer entropy analysis of electroencephalogram based on adaptive template method
Authors: Wang Ying  , Hou Feng-Zhen  , Dai Jia-Fei  , Liu Xin-Feng  , Li Jin  , Wang Jun  ,   Key Laboratory of Image Processing and Image Communications of Jiangsu Province, Nanjing University of Posts and Telecommunications, Nanjing 210003, China;,   School of Science, China Pharmaceutical University, Nanjing 210009, China;,   Neurology Department, Nanjing General Hospital of Nanjing Military Command, Nanjing 210002, China;,   College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

Electroencephalogram (EEG) is a very weak random signal with complex mechanism, which comprehensively reflects the activities and the functional states of brain tissue. Due to the weak characteristic of EEG, the traditional basic template method is a good tool for EEG analysis. In order to further enhance the performance of this method, we propose a new transfer entropy method based on adaptive template. The method improves the symbolization of time series based on the original basic template method. Numerical experiments show that the improved adaptive template method can obtain better dynamic characteristics, and also has better ability to distinguish the results in the analysis of time series. We use the transfer-entropy-based adaptive template method to analyze adolescent and adult EEG. We also study the relationship of the transfer-entropy-based adaptive template method to the total data length L and the data length l of the divided cells. Numerical results show that the transfer entropy value of adult EEG based on adaptive template is significantly higher than that of teenager EEG. This indicates that adult has a more significantly mental activity and the functional status of the brain is more complex. We then apply this method to human EEG signals and investigate their statistical properties. The results show that compared with the result of the basic method, the transfer-entropy-based adaptive template method can significantly show the EEG coupling for adolescents and adults EEG, which has a better discrimination and can better capture dynamic information and the change of the system dynamic complexity. At the same time, it will be more conducive to clinical diagnosis and provides a new and better method to judge whether brain is in a pathological state.
A blind source separation method for chaotic signals based on artificial bee colony algorithm
Authors: Chen Yue  , Lü Shan-Xiang  , Wang Meng-Jiao  , Feng Jiu-Chao  ,   School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641, China
Published: December 2020

The inherent features, such as non-periodic, wide band spectrum, and extreflely sensitive to initial values etc. make it quite a challenge to blindly separate the mixed chaotic signals. A new blind source separation method based on the artificial bee colony algorithm is proposed in this paper. This method can recover chaotic sources from noisy observations on their linear mixtures without any prior information about the source equations. The proposed method is structured in the phase space of the demixed signals, which is reconstructed from the observations by using delay-embedding method. An objective function in the reconstructed phase space is designed so that the blind source separation problem is transformed into an optimization problem. The optimal demixing matrix is obtained by maximize the objective function with an artificial bee colony optimizer and the chaotic sources are then recovered by multiplying the observed mixtures and the optimal demixing matrix. Before the optimization procedure is made, a pre-whitening should be employed. Additionally, the parameterized repreflentation of orthogonal matrices through principal rotation is adopted to reduce the dimension of the optimization procedure so that the proposed blind source separation algorithm can converge quickly. Different from the traditional independent component analysis approaches which concern mainly the statistical features, the proposed blind source separation method utilizes the dynamics in the observed mixtures by means of phase space reconstruction. Therefore, better performance can be achieved when it is used to deal with chaotic signals.
In computer simulation, two cases are taken into consideration: namely, the mixture is noiseless or not contaminated by noise. The correlation coefficient criterion and the performance index criterion are adopted to evaluate the separation performances. Simulation result shows that in most cases the proposed approach converges within a few tens of iterations and the chaotic sources can be accurately recovered. The impact of noise level and signal length on the separation performance is investigated in detail. The overall performance of the proposed approach is much better than the traditional independent component analysis approaches. Moreover, the capability of separating the mixed chaotic and Gaussian signals reflealed in the simulation indicates that the proposed approach has the potential to be applied in a wider range of applications.
Low-RCS waveguide slot array antenna based on a metamaterial absorber
Authors: Li Wen-Qiang  , Cao Xiang-Yu  , Gao Jun  , Zhao Yi  , Yang Huan-Huan  , Liu Tao  ,   School of Information and Navigation of AFEU, Xi’an 710077, China
Published: December 2020

A method of reducing the in-band radar cross section (RCS) of waveguide slot array antenna by utilizing a metamaterial absorber (MA) is preflented. A novel ultra-thin (the thickness is only 0.01λ, λ is the wavelength corresponding to the MA resonant frequency) MA with high absorptivity and no surface lossy layer is designed; the absorber is composed of two metallic layers separated by a lossy dielectric spacer. The top layer consists of an etched oblique cross-gap patch set in a periodic pattern and the bottom one is a solid metal. Effective impedance of MMA will match the free space impedance by adjusting the dimensions of electric resonant component and magnetic resonant component in the unit cell, and so the reflection will be minimized. Meanwhile, the MMA can obtain a resonant loss to fulfill the high absorption. By finely adjusting the geometric parameters of the structure, we obtain the MA with absorption 99.9%, and its absorbing mechanism being interprefled by analyzing surface current, surface electric field, and volume power loss density distribution, respectively. The metallic area between slots in E plane direction of waveguide slot array antenna is covered by MA, and a distance between the radiating slot and the MA is suitably arranged. Antenna radiation performance is kept in good order because this arrangement does not destroy the amplitude distribution of antenna aperture, and the high absorptivity of MA that contributes the reduction of structure mode scattering. Simulation and experimental results demonstrate that the array antenna loaded with MA gets more than 6 dB RCS reduction both in the x-and y-polarized incident conditions; and the RCS of antenna has obviously a reduction from -25° to +25°, the most reduction value exceeds 10 dB in the boresight direction, while the reflectance, gain and beam width are guaranteed. This idea has an important significance and engineering application for the RCS reduction of array antenna.
A precision evaluation method of USBL positioning systems based on LBL triangulation
Authors: Han Yun-Feng  , Li Zhao  , Zheng Cui-E  , Sun Da-Jun  ,   College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China;,   Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Ultra short baseline (USBL) positioning system is widely used in underwater geophysical field survey, acoustic tow fish positioning, and sea oil engineering The precision and accuracy are important technical indexes. Normally, people often care about how to improve the precision of position, but there is no unified method about how to evaluate the precision and accuracy. In most experiments, a beacon as target is moored on the seafloor using buoyancy, and survey positions of the beacon refleatedly in a circle track. The waviness of positioning results is used to evaluate the precision, which is analyzed by a statistical method. This paper analyzes the precision evaluation method based on error ellipse, gives the theoretical formulations, and proves the relationship between observation data and error ellipse. This paper also proposes a precision evaluation method of USBL positioning systems based on long baseline (LBL) triangulation, using the obtained result as the true position to evaluate the accuracy of USBL which can offer suggestions to find system error. Using multiple observations to increase redundancy, the precision is far greater than USBL positioning method. Estimated positions can be used as the true ones to serve as a reflerence in evaluating the accuracy. If the deviation between estimated positions using the USBL and LBL methods is larger than expected, the system needs to be recalibrated. Finally, this paper processes the data from sea experiment. The actual sea trial is processed using the LBL method proposed in this paper. Result shows that the precision of a fixed target is well reflected and the system error is modified further, and thus improves the positioning precision of 0.2%. Result also shows that this method may be of a great application value.
Separation of elasto acoustic scattering of underwater target
Authors: Xia Zhi  , Li Xiu-Kun  ,   Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China;,   College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

An elastic acoustic scattering by underwater target could be mixed with other acoustic scattering components in both time and frequency domains, and the existing signal processing methods could not discriminate the elastic feature of target in the mixed status. For solving this problem, a signal separation method for elastic acoustic scattering is proposed. Based on the highlight model of target echo, the characters of the target acoustic scattering signal when the linear frequency modulation signal is transmitted, are analyzed, and a method for mapping the acoustic scattering signal of the target to a single frequency signal is proposed. Theoretical derivation shows that there is a simple linear relationship between the acoustic scattering structure of the target and the mapped result, then the elastic acoustic scattering signal of the target can be separated by a narrow-band filtering. Simulation results show that the correlation coefficient between the separated target acoustic scattering and the orginal simulation signals are about 0.99, indicating that the acoustic scattering components in the simulation target echo can be wholly separated. Experimental data-processing results of the target acoustic scattering measureflent in an anechoic pool show that the mid-frequency enhancement effect can be observed in the spectrum of the separated elastic acoustic scattering, and every target acoustic scattering component can be recognized on the time-frequency distribution of separately processed target echo. There is a bowl-shape interference fringe on the angle-spectrum of the separated target elastic acoustic scattering components which is consistent with the theoretical signal’s feature of the elastic acoustic scattering, and the effectiveness of the separation method proposed is proven.
Study on magnetic and optical properties of Mn-doped LiNbO3 by using the first principles
Authors: Wang Fan-Hou  , Yang Jun-Sheng  , Huang Duo-Hui  , Cao Qi-Long  , Yuan Di  ,   Computational Physics Key Laboratory of Sichuan Province, Yibin University, Yibin 644007, China;,   Department of Physics and Electronic Engineering, Yibin University, Yibin 644007, China
Published: December 2020

According to density functional theory of first-principles calculation theory, we study systematically the structure, magnetism, electronic and optical properties of Mn-doped LiNbO3. The enthalpies of formation of LiNbO3, when substituting Li and Nb with Mn, are -8.340 and -8.0062 eV/atom, respectively. This means that the LiNbO3 after substitution of Li with Mn is more stable than that of Nb with Mn. And the magnetic moments of LiNbO3 in the substitution of Li with Mn is higher than that in substitution of Nb with Mn. Results of the density of states calculation show that the magnetism comes from Mn atom, and its magnetic moments is 4.3 μB. The rest of the magnetic moments may come from the contribution of the O and Nb atoms, because of the interactions of Mn-3d orbit with the O-2p and Nb-4d orbits. Optical absorption spectra show an improved optical response in the visible range in LiNbO3 by substituting Li with Mn. Results of analysis of oxygen vacancy in LiNbO3 show that oxygen vacancy can improve the magnetic moments of Mn-doped LiNbO3 system.
A modified design of pulse sequence and inversion method for D-T2 two-dimensional NMR
Authors: Fan Yi-Ren  , Wu Fei  , Li Hu  , Huo Ning-Ning  , Wang Yao-Sen  , Deng Shao-Gui  , Yang Pei-Qiang  ,   School of Geosciences in China University of Petroleum, Qingdao 266580, China;,   CNPC Key Laboratory for Well Logging in China University of Petroleum, Qingdao 266580, China;,   Research Institute of Shenzhen Branch, CNOOC Co., Ltd., Guangzhou 510240, China;,   Shanghai Niumag Electronic Technology Co., Ltd., Shanghai 200333, China
Published: December 2020

In face of the increasingly complicated exploration targets, D-T2 2D NMR technology cannot balance the range of diffusion coefficient and transverse relaxation resolution in practice. As the key technique of D-T2 2D NMR, the property of pulse sequence affects its application. A modified design of bivariate D-T2 pulse sequence based on pulsed field gradient is proposed after summarizing the technical characteristics of PFG, STE-PFG, BP-PFG, modified CPMG, “diffusion editing” and multi echo interval CPMG pulse sequences, which effectively integrates the advantages of D-T2 pulse sequences based on pulsed field gradient and constant field gradient. In order to reduce the difficulties that the existing D-T2 inversion methods cannot balance the inversion efficiency and accuracy, we propose a joint TSVD inversion method which sets the echos from the second window as the main part supplemented by the echos from the first window. Numerical simulation results for gas-water, oil-water, heavy oil and gas-oil-water models in different SNRs indicate that the D-T2 modified pulse sequence can balance the diffusion coefficient measureflent range and transverse relaxation resolution successfully, and the joint TSVD inversion method balances the inversion efficiency and accuracy successfully. Above all, the D-T2 modified pulse sequence and the joint TSVD inversion method have wide applications in the exploration and formation evaluation for unconventional reflervoir, and create favorable conditions for the development of D-T2 2D NMR technology.
Propagation of electric field of the few-cycle femtosecond pulse in nonlinear Kerr medium
Authors: Liu Dan  , Hong Wei-Yi  , Guo Qi  ,   Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou 510006, China
Published: December 2020

In this paper, the propagation of a few-cycle femtosecond pulse in a nonlinear Kerr medium is studied by the method of time-transformation. The time-transformation approach can greatly improve the computational efficiency. Because the width of electric field of the few-cycle femtosecond pulse is less than the characteristic time of Raman response in a nonlinear medium, it is observed that the electric field of the pulse experiences a significant deformation and breaks into a Raman soliton and the dispersion waves during the propagation, which can be attributed to strongly nonlocal nonlinearity. A deeper investigation of the time-frequency distributions for both the Raman soliton and the dispersion waves is also included. Since the pulse contains only few cycles, the carrier-envelope phase (CEP) of the pulse plays an important role in the process of nonlinear propagation. The numerical results show the CEP-dependence in the process of nonlinear propagation: the phase changes for both the Raman soliton and the dispersive waves are just equal to the CEP change of the initial pulse, which indicates that the CEP of the pulse is linearly transmitted in the process of nonlinear propagation. This phenomenon can be attributed to the fact that the phase change due to the nonlinearity is only dependent on the intensities of the fields of both the Raman soliton and the dispersion wave, which are unchanged for all the CEPs.
Sensitive detection of ultra-weak infrared image using parametric frequency up-conversion and amplification
Authors: Zhang Teng-Fei  , Yang Jing  , Hou Yan-Xue  , Wang Wei-Wei  , Zhao Wei  , Zhang Jing-Yuan  , Cui Da-Fu  , Peng Qin-Jun  , Xu Zu-Yan  ,   Research Center for Laser Physics and Technology, Key Lab of Functional Crystal and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;,   College of Science, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

Optical parametric frequency up-conversion and amplification, used for ultra-weak infrared image detection, is investigated both numerically and experimentally. A circum-circle model of spatial filtering is proposed to suppress the parametric fluorescence background noise. Combining the spatial filter, image relay module and band-pass filter, the fluorescence noise is suppressed by 70%. Accordingly, the image quality is significantly improved and the peak signal-to-noise ratio is increased by 22%. Based on the 10 Hz, mJ-level, 355 nm picosecond pump laser, the weak infrared image is amplified and up-converted into the visible region, and over 1.3108 (82 dB) optical gain is obtained at the same time. Our experiment demonstrates that the detection sensitivity of the conventional uncooled CCD can be as high as 7.4 photons per pixel when the high gain OPA is used as an image preamplifier. The scheme in this paper is expected to be used in single-photon-level sensitive infrared imaging.
Electromagnetic properties of zigzag graphene nanoribbons with single-row line defect
Authors: Zhang Hua-Lin  , Sun Lin  , Wang Ding  ,   School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114, China
Published: December 2020

In this paper, electromagnetic properties of the zigzag graphene nanoribbon (ZGNR) with a single-row line defect are studied by using the first-principles method based on the density functional theory. The energy band structures, transmission spectra, spin polarization charge densities, total energies, and Bloch states of the ZGNR are calculated when the line defect is located at different positions inside a ZGNR. It is shown that ZGNRs with and without a line defect at nonmagnetic and ferromagnetic states are metals, but the reasons for it to become different metals are different. At the antiferromagnetic state, the closer to the edge of ZGNR the line defect, the more obvious the influence on electromagnetic properties of ZGNR is. In the process of the defect moving from the symmetrical axis of ZGNR to the edge, the ZGNR has a phase transition from a semiconductor to a half metal, and then to a metal gradually. Although the ZGNR with a line defect close to the central line is a semiconductor, its band gap is smaller than the band gap of perfect ZGNR, owing to the new band introduced by the defects. When the line defect is located nearest to the boundary, the ZGNR is stablest. When the line defect is located next nearest to the boundary, the ZGNR is unstablest. When the line defect is located nearest or next nearest to boundary, the ground state of the ZGNR is a ferromagnetic state. However, if the line defect is located at the symmetric axis of ZGNR (M5) or nearest to the symmetric axis, the ground state would be an antiferromagnetic state. At the antiferromagnetic state, the phase transition of M5 from a semiconductor to a half metal can be achieved by applying an appropriate transverse electric field. Without a transverse electric field, M5 is a semiconductor, and the band structures of up-and down-spin states are both degenerate. With a transverse electric field, band structures of up-and down-spin states near the Fermi level are both split. When the electric field intensity is 2 V/nm, M5 is a half metal. These obtained results are of significance for developing electronic nanodevices based on graphene.