bluuebunny/crossref_metadata_2025 huggingface dataset:
Ressenya a Eduard López-Chavarri, Memorias de un viaje a Italia. Introducció i edició de Rafael Roca, València, Institució Alfons el Magnànim-Centre Valencià d’Estudis i d’Investigació, 2019
Authors: Toledo Lourdes
Published: December 2020

Ressenya a Eduard López-Chavarri, Memorias de un viaje a Italia, introducció i edició de Rafael Roca, València, Institució Alfons el Magnànim-Centre Valencià d’Estudis i d’Investigació, 2019, 190 pp. ISBN: 978-84-7822-814-0
Review to Eduard López-Chavarri, Memorias de un viaje a Italia, introducció i edició de Rafael Roca, València, Institució Alfons el Magnànim-Centre Valencià d’Estudis i d’Investigació, 2019, 190 pp. ISBN: 978-84-7822-814-0
TESTING SIMILARITY COEFFICIENTS FOR ANALYSIS OF THE FOSSIL RECORD USING CLUSTERING METHODS: THE PALAEOZOIC FLORA AS A STUDY CASE
Authors: Cascales-Miñana Borja
Published: December 2020

This paper reports a global methodological approach based on the similarity and clustering methods of the Palaeozoic plant fossil record using a comparative approach between two similarity measures: the Jacard and Raup-Crick Coefficients. The results show that although the Raup-Crick Coefficients clearly have the potential for providing more robust results, the consequences of the extinction processes are better reflected in the similarity analysis based on the Jaccard Coefficients. On the other hand, the cluster analysis based on UPGMA algorithm shows four robust clusters and reveals new evidence for the singularity of Mississippian flora. Finally, the results obtained reveal that similarity and cluster analysis are powerful tools to interpret the consequence of the processes modifying the taxonomic composition of the several analyzed Palaeozoic time units.
RECENSIÓN. Why evolution is true. Viking Penguin, New York [Por qué la teoría de la evolución es verdadera
Authors: Aguirre Julio
Published: December 2020

Resulta extremadamente curioso, cuanto menos sorprendente, el tremendo auge que han adoptado las ideas creacionistas como alternativa a la evolución en los últimos años. Si bien numerosas noticias relativas al problema de la enseñanza del creacionismo al mismo nivel que la teoría de la evolución nos llegan de Estados Unidos, deberíamos decir que este resurgir creacionista es algo más generalizado. Pero este problema no está únicamente en el ámbito de la educación, en la calle, los que piensan que no hemos evolucionado de especies anteriores llegan al ¡¡39% de la población!! A estos datos nada alentadores hay que añadir que un 21% no están seguros del todo y manifiestan sus dudas al respecto. Mucho me temo que estos datos nos dicen que aquí hay un problema de educación y de intrusismo.
Francamente, creo que Coyne ha escrito un libro que no deberíamos pasar por alto por varios motivos. En primer lugar, la lección esencial que nos ofrece este autor en este maravilloso libro es que la única forma posible de entender la gran riqueza y diversidad de formas de vida desplegadas por los organismos en la naturaleza es mediante la evolución. En segundo lugar, creo que es un libro fundamental desde una perspectiva didáctica ya que hay una ingente cantidad de ejemplos con los que continuamente trata Coyne de ilustrar cada prueba de la evolución. Finalmente, es la responsabilidad que recae sobre la Paleontología en el gran debate, “the high table” según los autores anglosajones, de la Evolución.
EDITORIAL
Authors: Gozalo Gutiérrez Rodolfo , Pardo Alonso Migue V
Published: December 2020

Ya han pasado ocho años desde que por primera vez editamos un número de nuestra revista, la Revista Española de Paleontología, y que entonces iniciábamos con un editorial en el que expresábamos nuestras intenciones y también nuestros deseos. Después de este tiempo, podemos decir que nuestras intenciones se han mantenido, y algunos de los deseos se han cumplido. Las principales intenciones eran mantener los niveles de calidad científica y de edición impresa, y la periodicidad de nuestra publicación; las dos primeras creemos haberlas mantenido, y es cosa de la que vosotros mismos, lectores y autores, podéis dar fe; en cuanto a la periodicidad, se ha podido mantener a pesar de la merma en el número de manuscritos y todo ello sin menoscabo de la calidad.
Icriodus riosi, NUEVA ESPECIE DE CONODONTO EN EL DEVÓNICO INFERIOR DEL PIRINEO CENTRAL ESPAÑOL
Authors: Martínez-Pérez Carlos
Published: December 2020

Se describe y discute el conodonto Icriodus riosi n. sp. del Devónico Inferior de los Pirineos Centrales Españoles. Esta especie se caracteriza por presentar un cuerpo principal con bordes rectos y un corto proceso posterior externo que forma un ángulo obtuso con el eje principal del elemento, estando ésta probablemente emparentada con las especies del grupo curvicauda-celtibericus. Su rango estratigráfico abarca desde la Zona pireneae (Praguiense tardío), ligeramente por debajo del comienzo de la Zona kitabicus, hasta la parte inferior de la Zona nothoperbonus (Emsiense inferior tardío). La abundante y diversificada asociación de diferentes especies del género en las mismas secciones, como por ejemplo Ic. curvicadua, Ic. celtibericus, Ic. bilatericrescens o Ic. gracilis, sugieren que durante este intervalo temporal se produjo un proceso de radiación evolutiva del grupo, fenómeno que hasta ahora sólo había sido documentado en el género Polygnathus.
Capacidad de nado del pingüino fósil: Inkayacu paracasensis Clarke, 2010 (Aves: Spheniscidae), con la tasa metabólica basal o estándar
Authors: Meza-Vélez Iván
Published: December 2020

El objetivo del estudio es calcular la capacidad de nado del pingüino extinto Inkayacu paracasensis en términos de la velocidad máxima de natación estimada, utilizando un método teórico biomecánico (mecánica de fluidos) aplicado a reptiles marinos mesozoicos y cetáceos vivos. A efectos comparativos, este parámetro también se calcula para el pingüino africano de patas negras Spheniscus demersus y el pingüino Emperador Aptenodytes forsteri. Los resultados muestran una velocidad máxima estimada de 2,8-3,4 m/seg, 2,8-3,5 m/seg y 3,0-3,7 m/seg, respectivamente. Las velocidades máximas observadas registradas en estudios con especies en cautiverio y en la naturaleza permiten corroborar los valores calculados para las especies vivas, con un error máximo de alrededor del 10% en el caso de A. forsteri. Por lo tanto, el pingüino Emperador e Inkayacu han desarrollado velocidades similares de natación. Además, se sugiere que la frecuencia del batido de la aleta, longitud de la zancada y fases de deslizamiento habrían sido similares en ambas especie de cuerpo grande, en contraste con las de menor tamaño. También se analiza la influencia del modelo de flujo (número de Reynold) en las tres especies de pingüinos. Se sugiere que la morfología del cráneo de Inkayacu podría ser una ventaja en la locomoción con respecto al pingüino Emperador.
El pensamiento Kuna o la utopía realmente existente
Authors: Chaparro Amaya Adolfo
Published: December 2020

Los kunas que habitan al noreste de la costa panameña son herederos de los más antiguos guerreros que resistieron tanto la conquista española desde comienzos del siglo XVI como el posterior asedio misionero y comercial del Estado modernizador. Sin pretender una etnografía detallada de los kuna, este texto plantea un estudio sistemático de aspectos nodales de su pensamiento jurídico, económico, estético y religioso. Explorando los recursos del lenguaje ritual, las formas de escritura y el pensamiento mítico, el texto muestra cómo los kunas responden y se vuelven receptivos al otro sin dejar de ser lo que son. El resultado es un sincretismo polifacético que demuestra la eficacia de la estrategia de intercambio sin integración para la continuidad de la máquina territorial kuna. Siendo la globalización de la forma Estado una suerte de utopía práctica en proceso de consolidación, la afirmación de una nación indígena que mantiene formas democráticas inspiradas en una tradición mítica singular se convierte en un desafío y una alternativa (a)histórica, vigente en su anacronismo, que resuena en comunidades étnicamente diferenciadas de todo el mundo. Sin ignorar la fragilidad del modo de existencia kuna, esa persistencia en la singularidad de su pensamiento, y en su fijeza étnica y territorial, se puede leer como un paradigma de política minoritaria, contrahegemónica, autoinmunitaria. En ese contexto, el texto cumple con la promesa metódica inicial: demostrar que siguiendo los avatares de una comunidad particular es posible deconstruir la oposición mito/utopía en su enunciación abstracta o ilusoria al poner en evidencia la fuerza utópica del mito como ethos comunitario de la experiencia histórica.
Security analysis of BB84 protocol in the collective-rotation noise channel
Authors: Li Jian  , Chen Yan-Hua  , Pan Ze-Shi  , Sun Feng-Qi  , Li Na  , Li Lei-Lei  ,   School of Computer Science, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China;,   Science and Technology on Communication Security Laboratory, Chengdu 610041, China
Published: December 2020

Most of quantum cryptography protocols are designed under the ideal conditions without considering the impact of noise in actual communication; thus they may result in that the confidential information cannot be transmitted to the receiver accurately or eavesdroppers can steal the confidential information by mixing in noise. Therefore, analyzing the security of quantum cryptography protocols under noise conditions is of great significance. For the purpose of analyzing the security of quantum BB84 protocol in collective-rotation noise, firstly this paper introduces the quantum BB84 protocol, and considers the influence of environmental noise on it. An explanation should be stated that in a noise environment, the effects of noise and eavesdropping cannot be distinguished between each other. So the mechanism for which the error bit is simply used as the criterion to judge whether there exists eavesdropping in the BB84 protocol, cannot be used in the noise environment. The mechanism to judge whether there exists eavesdropping in quantum noise channel needs to be modified and improved for protecting the information. An initial qubit error rate can be set according to the noisy quantum channel. If the qubit error rate of the quantum communication channel is larger than that, it can be determined that the quantum channel is not secure and exists eavesdropping, no matter what the reason is. And on this basis, the collective-rotation noise model will be established in quantum channel by using the particle deflection model and distinguish the noise from the eavesdropping in quantum channel quantitatively, and the relationship of the amount of information that eavesdroppers can steal, the quantum bits error rate and the noise level will be analyzed by using the von Neumann entropy. Finally, the noise critical point will be calculated by using the collective noise model and the relationship between the amount of information that eavesdroppers can steal, at the quantum bits error rate, and the noise level. Through the analysis, we can know that in the existing noise level, the most of the eavesdropping can steal 25% of the key from the communication. However, the Eve's eavesdropping behavior will be detected, so that Alice and Bob will give up the current consultation key, and restart the key negotiation. This result shows that the quantum BB84 protocol is safe and secure in the collective-rotation noise channel. The research results of this paper will enrich the theory of quantum cryptography, and the innovation of security detection methods in quantum cryptographic protocols will help promote the process of practical quantum cryptography.
Theoretical calculation of the photoelectron angular distribution of neon
Authors: Ma Kun  , Xie Lu-You  , Zhang Deng-Hong  , Dong Chen-Zhong  , Qu Yi-Zhi  ,   School of Information Engineering, Huangshan University, Huangshan 245041, China;,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;,   College of Material Sciences and Opto-electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The general formula of the angular distribution of photoelectron is derived by using the density matrix theory and Racah algebra method. For comparing with the experimental data, the general formula in this paper is matched to the parametric formula and the non-dipole parameters of the photoelectron angular distribution associated with the terms of the second order for both unpolarized and polarized incident light are given explicitly. From the formula of these parameters we can see that the contribution to the non-dipole parameter is from the interference between dipole amplitude and multipole amplitude. And then, the relativistic calculation program for photoelectron angular distribution is further developed with the help of the program packages GRASP2K and RATIP which are based on the multi-configuration Dirac-Fock method. By using this program, the dipole and non-dipole angular-distribution parameters for neon 2s and 2p photoelectrons are calculated concretely. The good agreement between the results of this paper and the available theoretical data is obtained in a 50-5000 eV photoelectron-energy range studied. On this basis, the angular photoelectron distributions for neon 2s and 2p are calculated with and without considering the second non-dipole terms at the photoelectron energy E=600 eV and E=5000 eV, respectively. Special attention is paid to the effects of the polarization property of incident light and the non-dipole terms of photo-electron interaction on the angular distribution of photoelectrons. The results show that 1) the dipole and non-dipole parameters of the photoelectron angular distribution are sensitive to the ionized electron orbital, it can bring out considerable diversities among the photoelectron angular distributions of the different shells; 2) non-dipole effects make the photoelectron forward distribution in the direction of incident light, the polarization property of incident light will strengthen the asymmetric distribution of photoelectrons.
Novel multiple field of view detection method for the off-axis reflection zoom optical system
Authors: Zhou Ji-De  , Chang Jun  , Niu Ya-Jun  , Xie Gui-Juan  , Wang Xi  ,   School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

In order to study the computer-aided alignment for the off-axis reflective zoom optical system, the wavefront aberration of the off-axis reflective zoom system across the field of view needs to be detected. Obtaining the wavefront aberration across the field of view could improve the accuracy of the computer-aided alignment for the off-axis reflective zoom optical system. Restricted by the current wavefront aberration detection technology, only the wavefront aberration at a field degree of 0 could be detected. To solve this problem, a new method to detect the wavefront aberration of off-axis reflective zoom system across the field of view is proposed. According to the traditional autocollimation interferometry method, we improve the detection method by substituting the scan of standard plane mirror with the deformable mirror, replacing the interferometer with Shark-Hartmann sensor and employing the accurately calibrated laser source array to realize the wavefront aberration detection at multiple field of view simultaneously. The simulation shows that the residual wavefront aberration root-mean-square values after compensating for the deformation mirror in the following 6 fields of view (0, 3), (0, 4.2), (0, 5.5), (0, 7), (0, 9.8), and (0, 14) are 0.00039, 0.00075, 0.00024, 0.00017, 0.00053, and 0.0057, respectively. It shows that the detection method we proposed is suitable for the computer-aided alignment technology for the off-axis reflective zoom system.
Lattice Boltzmann simulation of the droplet impact onto liquid film
Authors: Huang Hu  , Hong Ning  , Liang Hong  , Shi Bao-Chang  , Chai Zhen-Hua  ,   School of Mathematics and Statistics, Huazhong University of Science and Technology, Wuhan 430074, China;,   School of Information and Engineering, Wuchang University of Technology, Wuhan 430223, China;,   Department of Physics, Hangzhou Dianzi University, Hangzhou 310018, China;,   State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

The process of the droplet impact onto the liquid film, as one of the basic multiphase problems, is very important in many fields of science and engineering. On the other hand, the problem is also very complicated since there are many parameters that may influence the process of the droplet impact on the liquid film. To clearly understand the physical phenomena appearing in the process droplet impact on the liquid film, a parametric study on this problem is conduced based on a recently developed lattice Boltzmann method in which a lattice Boltzmann model is used to solve the Navier-Stokes equations, and the other is adopted to solve the Cahn-Hilliard equation that is used to depict the interface between different phases. In this paper, we mainly focus on the effects of the Reynolds number (Re), the Weber number (We), the relative thickness of film (h) and the surface tension () on the dynamic behavior of interface between different phases, and the velocity and pressure fields are also presented. It is found that with the increase of Re and We, the phenomena of crown and entrainment can be observed obviously during the process of droplet impact onto the liquid film, and the radius of the crown seems not dependent on the We and Re where the relative thickness of film and surface tension are fixed to be 0.5 and 0.003. However, when Re becomes much larger, the splashing phenomenon is produced, and the small droplets caused by the splashing can fall and then impact onto the liquid film again. We also find that if the relative thickness of film is small, the surface tension, Re and We are set to be 0.003, 480 and 500, the film can break up during the process of the droplet impact onto the liquid film, while with the increase of relative thickness, although more liquid are induced in the splashing process, the film cant break up. In addition, with the increase of surface tension, the resistance which prevents the change of interface becomes large, and thus the change of interface is not large when the droplet impacts onto liquid film, as expected. And finally, a quantitative study on the relation between the radius of crown (formed by droplet impact onto liquid film) and the time is also performed, and the expression r/(2R) Ut/(2R) where the parameter is about 1.0 and is also independent of We and Re, can be used to describe the relation.
Wetting and brazing of AlN by sputtered Al
Authors: Zhao Bo-Wen  , Shang Hai-Long  , Chen Fan  , Shi Kai-Cheng  , Li Rong-Bin  , Li Ge-Yang  ,   State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China;,   Shanghai Engineering Institute, Shanghai 201306, China
Published: December 2020

The wettabilities of molten metals on ceramics are poor normally. In order to improve the wettability, all existing ceramic brazing methods introduce a compound transition layer that is formed by the reaction of active metal and ceramic. The transition layer between brazing seam and ceramic however creates negative effect on the properties of brazing joints. This paper reports our study of the wetting effect of sputtered Al particles on AlN, which enables the direct brazing of AlN using deposited Al-based films as fillers, thereby eliminating the need of a transition layer. The results show that under the bombardment of energetic sputtered Al particles, Al-N chemical bonding is formed at the interface between Al film and AlN, which typically requires temperatures above 850 ℃, much higher than the melting point of Al. The bonding remained intact even after the Al film has been melted, achieving the wetting effect on AlN. As a result, the direct brazing of AlN without the need of a transition layer becomes feasible. The shear strength of Al/AlN joint using this process reaches 104 MPa. The addition of 3.8 at.% Cu to film fillers increases the shear strength to 165 MPa. The fracture is generated in metallic brazing seam in both cases. When Cu content increases to 9.1 at.%, the segregation of Cu at the interface between the brazing seam and the ceramic reduces the shear strength of the joint to 95 MPa. With Al-20 at.% Ge, the brazing temperature can be lowered to 510 ℃, although the segregation of Ge at interface results in a low shear strength of 48 MPa. Instead of the traditional use of molten metals, utilization of the metallic vapor particles to bombard AlN achieves the wetting and the direct brazing of ceramics, with no negative effect of transition layers. This breakthrough method provides a brand new perspective to the technique of ceramic brazing.
Investigation of V doped ZnO transparent conductive oxide films
Authors: Wang Yan-Feng  , Meng Xu-Dong  , Zheng Wei  , Song Qing-Gong  , Zhai Chang-Xin  , Guo Bing  , Zhang Yue  , Yang Fu  , Nan Jing-Yu  ,   Institute of New Energy Science and Technology of Hebei North University, College of Science, Hebei North University, Zhangjiakou 075000, China;,   College of Science, Civil Aviation University of China, Tianjin 300300, China
Published: December 2020

The performance of the ZnO film that is an indispensable part of pin-type Si-based thin-film solar cells, plays a crucial role in high-efficiency thin-film solar cells and also forms a significant part in photovoltaic research and development. In this paper, low resistivity and wide broadband spectrum transmittance vanadium (V) doped ZnO (VZO) films are successfully fabricated on Corning XG substrates at various substrate temperatures (STs). The properties of VZO films are investigated by the radio-frequency magnetron sputtering technique and plane wave pseudo-potential method based on the density-functional theory. The experimental results demonstrate that all the VZO flms have (002) preferred orientation with the c-axis perpendicular to the substrate, and the crystalline quality is found to increase with the substrate temperature (ST) rising up to 280 ℃ and decrease when the ST increases further. The optimal VZO film is achieved at 280 ℃ with a resistivity of 3.810-3 cm and an average transmittance of more than 85% in a range of 500-2000 nm. The theoretical result shows that after incorporation of V the Fermi level goes through the conduction band, showing a typical n-type metallic characteristic. The carriers originate from the orbits of V 3d and O 2p. The calculated lattice constants and mobility for VZO film are in agreement well with the experimental results. The consistency of the theoretical results with the experimental results shows that the VZO thin film has a great potential application as a front contact in high-efficiency thin film solar cells.
Healing of oxygen defects on VO2 surface: F4TCNQ adsorption
Authors: Wang Kai  , Zhang Wen-Hua  , Liu Ling-Yun  , Xu Fa-Qiang  ,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
Published: December 2020

Oxygen-defect vacancies that routinely exist in wet production of VO2 material or on the surface of VO2 single crystal after surface treatment have significant influence on the metal-insulator phase transition features mainly due to their enhanced effect of doping on V 3d electronic structure. The removal of the surface oxygen defects is highly desired for investigating the VO2 intrinsic electronic properties. In this work, we propose a charge transfer doping method by using strong electric affinity molecule tetrafluorotetracyanoquinodimethane (F4TCNQ) adsorption rather than the normal thermal annealing in oxygen atmosphere to heal the surface oxygen defects of VO2 crystalline film. The healing effect is probed by the electronic structure evolution at the F4TCNQ/VO2 interface. The VO2 crystalline film is grown by an oxygen plasma assisted molecular beam epitaxy method on an Al2O3(0001) substrate. Surface oxygen defects on VO2 film are produced after a mild sputtering with an ionic energy of 1 keV and a thermal annealing in vacuum at 100 ℃. The influence of F4TCNQ molecule adsorption on the electronic structure of the sputtered VO2 film is studied by using in-situ synchrotron-based photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). XPS and XAS results demonstrate convincingly that V3+ species of sputtered VO2 are oxidized into the V4+ and simultaneously negative molecular ions form at F4TCNQ/VO2 interface resulting from the electron transfer from VO2 to the F4TCNQ layer. The preferred adsorption on surface defects and the strong electron withdrawing function of F4TCNQ molecules may account for the effective elimination of the electron doping effect of oxygen defects on VO2 surface. This charge transfer effect at interface recovers the electronic properties of VO2. Compared with thermal annealing in oxygen environment, the healing of oxygen defects by the molecular adsorption can prevent the surface from over oxidating VO2 into V2O5, which opens a new route to surface defect healing.
Cumulants and waitingtime distribution of the photon emission from driven BaF molecule
Authors: Gu Li-Shan  , Peng Yong-Gang  ,   Department of Physics, Changji University, Changji 831100, China;,   School of Physics, Shandong University, Jinan 250100, China
Published: December 2020

In this paper, we consider a single BaF molecule driven by an external field. When the symmetry is broken, the states of the BaF molecule demonstrate the permanent dipole moments. An external laser field to excite BaF molecule transition from its ground state to its excited state, and a radio frequency field couple with the permanent dipole moment of the BaF. The first order and second order cumulants of the emission photons and the waiting time distribution are studied via the recently developed generating function approach, which is very convenient to study the counting statistics and the corresponding probability distributions. The results demonstrate that the radio frequency field could help the BaF molecule to absorb photons from the driving field. The second and third order waiting time distributions oscillate with the evolution time, which reflects the states oscillating with the external radio frequency field.
Analysis of sound propagation in the direct-arrival zone in deep water with a vector sensor and its application
Authors: Sun Mei  , Zhou Shi-Hong  , Li Zheng-Lin  ,   State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Physics and Electronic Engineering, Taishan University, Taian 271000, China
Published: December 2020

The receiver at larger depth can receive the direct-arrival signal from a shallow source in a certain range in deep water. During a deep-water experiment conducted in 2014, a vector sensor located at a depth of 3146 m received the direct-arrival signals from the transducer towed at about 140 m depth by the source ship. In this paper, the propagation properties of the sound field in the direct-arrival zone in deep water are studied based on the ray theory and subsequently a source-range-estimation method is proposed. In the direct-arrival zone, the arrival angle is one of the most important properties of sound field, and the sound field is mainly composed of the contributions of a direct ray and a surface-reflected ray. The theoretical analysis and simulation results show that the amplitudes of horizontal particle velocity and vertical particle velocity are related to the mean arrival angle of the direct ray and the surface-reflected ray, and the larger the arrival angle, the greater the vertical particle velocity is, but the weaker the horizontal particle velocity is. Furthermore, the energy difference between horizontal particle velocity and vertical particle velocity can be approximately expressed by a monotonic function of the arrival angle, which varies fast with the horizontal distance between source and receiver. This property is applied to the estimation of source range. The analysis of the experimental data shows that the estimated source ranges are consistent with the GPS ranges within the range of 8 km, and the mean relative error of source range estimation is within 10%.
On modeling and physical laws of isentropic speed of sound in dense gas-particle two-phase compressible flows
Authors: Chen Da-Wei  , Wang Pei  , Yu Xi-Jun  , Sun Hai-Quan  , Ma Dong-Jun  ,   National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;,   Graduate School of China Academy of Engineering Physics, Beijing 100088, China
Published: December 2020

Study of isentropic sound speed of two-phase or multiphase flow has theoretical significance and wide application background. As is well known, the speed of sound in fluid containing particles in suspension differs from that in the pure fluid. In the particular case of bubbly liquids (gas liquid two-phase flow), the researches find that the differences can be drastic. Up to now, the isentropic speed of sound in the flow field with a small volume fraction of bubbles (less than 1%), has been investigated fully both experimentally and theoretically. In this paper, we consider another situation, as the case with solid particles in gas, which is the so-called gas particle two-phase flow. Although many results have been obtained in gas liquid two-phase flow, there is still a lot of basic work to do due to the large differences in the flow structure and flow pattern between gas particle two-phase flow and gas liquid two-phase flow. Treating the gas particle suspension as the relaxed equilibrium, thermodynamic arguments are used to obtain the isentropic speed of sound. Unlike the existing work, we are dedicated to developing the computational model under dense condition. The space volume occupied by particle phase and the interaction between particles are overall considered, then a new formula of isentropic sound speed is derived. The new formula includes formulae of the pure gas flow and the already existing dilute gas particle two-phase flow as a special case. On the one hand, the correctness of our formula is verified. On the other hand, the new formula is more general. The variations of sound speed with different mass fractions of particle phase are analyzed. The theoretical calculation results show that the overall physical law of sound speed change is that with the increase of the particle mass fraction, the sound speed first decreases and then increases. The velocity of sound propagation in gas particle two-phase flow is far smaller than in pure gas in a wide range, so it is easy to reach the supersonic condition. When the particle volume fraction is below 10%, the result is consistent with Prandtl theoretical analysis. In this range, the influences of the particle phase pressure modeling parameters can be neglected. When the particle volume fraction is more than 10%, the particle phase pressure modeling parameters produce influences. Furthermore the corresponding physical principles and the mechanisms are discussed and revealed. The new formula and physical understandings obtained in this paper will provide a theoretical support for the researches of dense gas particle two-phase compressible flow and related engineering applications.
Calibration of the dynamic spatial resolution of framing image-converter
Authors: Yuan Zheng  , Dong Jian-Jun  , Li Jin  , Chen Tao  , Zhang Wen-Hai  , Cao Zhu-Rong  , Yang Zhi-Wen  , Wang Jing  , Zhao Yang  , Liu Shen-Ye  , Yang Jia-Min  , Jiang Shao-En  ,   Reserch Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In order to improve the two-dimensional imaging diagnostic accuracy of inertial confinement fusion (ICF) experiment, a calibration method of the dynamic spatial resolution of X-ray framing image-converter (XFIC) is proposed. When an object with straight edge function is projected onto the photocathode of XFIC as an input, edge spread function can be obtained by recording an image of the XFIC output. The first derivative of the edge spread function produces the line spread function (LSF). Then the modulation transfer function (MTF) of the system can be worked out by Fourier transform of the LSF. Therefore, the spatial resolution can be deduced. According to this theory, the spatial resolution of XFIC can be obtained. Based on SG-Ⅱ laser facility, the calibrating X-ray source is generated by 8 bundled lasers bombarding the target. High-Z knife-edge is irradiated by the X-ray and imaged on the photocathode of XFIC, and then a dynamic image is obtained as the system works in the gating mode. By handling the dynamic image, the LSF of XFIC is given by analyzing the edge image. Then the MTF of the camera can be indicated by the Fourier transform of the LSF. When the MTF is 0.1, the corresponding spatial resolution of the imaging system is 20 lp/mm. According to the dynamic spatial resolution theory of framing image-converter, the extreme spatial resolution is 22.8 lp/mm. The calibration result agrees with the theoretical results. By contrast, the static spatial resolution of the same X-ray framing image-converter calibrated by the traditional method is presented here. The calibrated static spatial resolution is 22 lp/mm, a little higher than the dynamic one. During the two-dimensional imaging diagnosis, the X-ray framing image-converter works in the dynamic gating mode, thus the calibrated dynamic spatial resolution can be more truthful to reflect its imaging diagnosis ability.
Switching characteristics of all spin logic devices based on Co and Permalloy nanomagnet
Authors: Wang Sen  , Cai Li  , Cui Huan-Qing  , Feng Chao-Wen  , Wang Jun  , Qi Kai  ,   Science College, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

The need for low-power alternatives to digital electronic circuits has aroused the increasing interest in spintronic devices for their potentials to overcome the power and performance limitations of (CMOS). In particular, all spin logic (ASL) technology, which stores information using the magnetization direction of the nano-magnet and communicates using spin current, is generally thought to be a good post-CMOS candidate for possessing capabilities such as nonvolatiliy, high density, low energy dissipation. In this paper, based on nano-magnetic dynamics described by Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation and transport physics of spin injection and spin diffusion, a coupled spin-transport/magneto-dynamics model for ASL is established. Under different channel lengths and applied voltages, the switching characteristics of ASL device comprised of Co and Permalloy (Py) nano-magnets are analyzed by using the coupled spin-transport/magneto-dynamics model. The results indicate that the switch delay, energy dissipation and thermal noise effect of PyASL are lower than those of CoASL. The main reason is that the saturation magnetization of Py is less than that of Co. Under the same applied voltage, the maximal channel length of PyASL is longer than that of CoASL when ASL device can switch accurately. Moreover, the two ASL devices' switching delay can be reduced by reducing channel length or increasing applied voltage, and the energy dissipation can be reduced by reducing channel length or applied voltage, whereas there are no optimized applied voltages to minimize the energy-delay product. In addition, the influences of thermal noise on switching delay and energy dissipation can be improved by lowering channel length, but increasing applied voltage can only improve the influence of thermal noise on switching delay. The above-mentioned conclusions will supply essential guidelines for optimizing the ASL devices' materials and configuration.
Thermal-structural coupling analysis of beam screen in super proton-proton collider
Authors: Fan Jia-Kun , Wang Jie , Gao Yong , You Zhi-Ming , Wang Sheng , Zhang Jing , Hu Yao-Cheng , Xu Zhang-Lian , Wang Bin ,   Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology &   State Key Laboratory of Multiphase Flow in Power Engineering, Shaanxi Engineering Research Centre of Advanced Nuclear Energy, Xi’an Jiaotong University, Xi’an 710049, China,   School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

High-energy colliders play an indispensable role in particle physics and high-energy physics. Beam screen is one of the key parts in the high-energy collider. It is used to transfer the heat generated by the beam in the pipeline to a cooling system, and absorb the residual gas to the cold bore through the pumping holes on the wall of the beam screen to ensure the vacuum stability at the same time. However, in the process of transferring thermal load, the deformation caused by temperature change will affect the structural stability of the beam screen. How to reduce the deformation as much as possible while ensuring the good heat transfer performance of the beam screen is one of the key issues in optimizing the structural design of the beam screen. In this paper, the heat transfer performance and mechanical property of the beam screen model are simulated and optimized based on the ANSYS simulation results to ensure the normal and stable operation of the beam in the super proton-proton collider. For the inner surface of the outer screen of the beam screen, the method of reducing the thickness of the copper coating is used to reduce the Lorentz force generated during operation. The calculation results from the relevant theoretical models show that when the thickness of the copper coating varies from 0 to 100 μm, the copper coating with a thickness of 75 μm can reduce the maximum deformation of the outer screen of the beam screen by 70.9%, while the maximum temperature of the beam screen can be increased by 1.1%. For the inner screen of the beam screen, a design scheme in which supporting ribs are arranged at intervals is used to reinforce the structure and improve the overall structural stability of the beam screen. The calculation results show that the maximum deformation of the inner screen of the beam screen can be reduced by 86.8% and the maximum temperature of the beam screen is reduced by 7.69%, compared with the case without supporting fins, when the interval between two adjacent supporting fins is 1 pumping hole. The research results provide important theoretical reference for the design of beam screen, which is the key component of the vacuum system of the new-generation high energy particle accelerator.
Microorganism identification and environmental cleaning effectiveness in radiology settings: cross-sectional and experimental studies
Authors: Ding Sandrine , Weber Nicolas , Oppliger Anne
Published: December 2020

Introduction: Despite the large number of patients passing through and some invasive procedures, radiology may still be considered unlikely to transmit pathogens. However, radiation protection aprons touched by radiology professionals and shared between patients could be prone to contamination. Our goals were to (1) assess qualitatively and quantitatively the microorganisms present on the radiation protection aprons with a cross-sectional study, and (2) determine the effectiveness of routine cleaning with an experimental design.

Methods: For objective 1, 108 samples were collected on radiation protection aprons of two radiology settings: the diagnostic radiology (DR) setting, with a cleaning procedure in place, and the emergency setting without. Total cultivable bacteria, staphylococci, enterobacteria and fungi were quantified. For purpose 2, the number of total bacteria and staphylococci were compared between before and after cleaning the aprons.

Results: The median number of total bacteria were respectively 0.97 and 1.56 cfu/cm2 in the DR and emergency settings, whereas the median number of Staphylococcus were 0.04 and 0.15 cfu/cm2 in these settings (Objective 1). Thus the number of microorganisms were lower in the setting with the cleaning procedure, although significantly only for staphylococci (p = 0.025). Enterobacteria, fungi and Staphylococcus aureus were not detected in any sample. In the second part of the study, the median number of total bacteria dropped from 0.80 to 0.17 cfu/cm2 between before and after cleaning (p = 0.0017) and for Staphylococcus it decreased from 0.84 to 0.15 cfu/cm2 (p = 0.13).

Conclusion: A number of microorganisms have been found, although the absence of enterobacteria, fungi and S. aureus is reassuring as they can cause serious healthcare-associated infections. Our study showed that the cleaning of radiation protection aprons can significantly reduce the microbial load and should be encouraged.
Identifying Twitter users who repost unreliable news sources with linguistic information
Authors: Mu Yida , Aletras Nikolaos
Published: December 2020

Social media has become a popular source for online news consumption with millions of users worldwide. However, it has become a primary platform for spreading disinformation with severe societal implications. Automatically identifying social media users that are likely to propagate posts from handles of unreliable news sources sometime in the future is of utmost importance for early detection and prevention of disinformation diffusion in a network, and has yet to be explored. To that end, we present a novel task for predicting whether a user will repost content from Twitter handles of unreliable news sources by leveraging linguistic information from the user’s own posts. We develop a new dataset of approximately 6.2K Twitter users mapped into two categories: (1) those that have reposted content from unreliable news sources; and (2) those that repost content only from reliable sources. For our task, we evaluate a battery of supervised machine learning models as well as state-of-the-art neural models, achieving up to 79.7 macro F1. In addition, our linguistic feature analysis uncovers differences in language use and style between the two user categories.
Access and Use of Latrines for Everyone? The Case of the Far North Region (Cameroon)
Authors: Nbendah P. , Wafo G. V. Djumyom , Kengne E. Soh , Nzouebet W. A. Letah , Wanda C. , Ayo A. , Fouedjio A. , Noutajie J. P. Fankem , Paul A. Atabong , Ngoukwa G. , Wafo A. J. Kamdem , Temegne C. Nono , Bell J. M.
Published: December 2020

Introduction: Difficulty of access to and use of decent latrines is one of the major concerns of our century. This, as it affects more than one billion people, particularly in the developing world. Even more, it affects the health of people and seriously hinders their development as well as their mental and social well-being. It is as a prelude to the foregoing that this study was conducted with the aim of assessing the type of devices and their level of use by households in Far North of Cameroon.

Methodology: An investigation was conducted among 1,050 households selected in a stratified manner in 56 villages in 10 communes of the Far North region during the year 2016. This through an evaluation of the type of device, as well as their level of use by households in this region.

Results: More than 80% of the latrines encountered are unimproved because they do not allow a safe separation between feces, humans and the environment. The percentage of use of these devices is 92.5% for the households surveyed, which is below the national level estimated at 94%. The non-users of latrines are either non latrine holders or latrine holders who prefer to relieve themselves in the open air.

Conclusion: The study revealed that the majority of households use latrines. However, these latrines are mostly unimproved. Open defecation is still practiced in some localities.

Impact of the study: This study provides the baseline situation for latrine use in the Far North and thus marks the starting point for any intervention to improve the situation of latrine access in this region.
Effects of Financial Dualism and Inclusion on Economic Development in Nigeria
Authors: Anyanwu G. I. , Okere P. A. , Adioha N. F.
Published: December 2020

This study examined the effects of financial dualism and inclusion on the economic development in Nigeria. Data were obtained principally from primary sources, interviews and questionnaires.  The sample for the study consisted of one hundred (100) respondents randomly selected from shop owners in Eke Ugwu market, in owerri capital territory. The qualitative data were transformed into quantitative form with the use of likert scale. The ordinary least square (OLS) estimation technique was employed to test for relationship in the model. The study revealed a significant relationship between financial inclusion and economic development in Nigeria. The study further revealed that the delivery of quality financial services at affordable price and terms to the generality of the populace especially the disadvantaged and lower income segment of the society is the essence of financial inclusion. This study therefore recommends that the monetary authorities should ensurethat banks offer prompt and timely services. Neck-to-measure services should be produced and made available to customers at affordable prices.  Again, Banks and other financial institutions should design appropriate packages that will assist in collaborating with the informal financial institutions so that the funds so far mobilized by them are integrated into the banking sector. This will reduce the volume of currency outside the banking sector.
Point of Sale and Cashless Policy in Nigeria: Challenges and Prospects
Authors: Anyanwu G. I. , Anumaka C. I.
Published: December 2020

The study examined the impact of Point of Sale (POS) on cashless policy, issues and prospect in Nigeria economy; research questions were formulated and distributed to the sample population of 500 drawn from various POS operating centers in line with the objectives of the study. Four hundred and fifty  responses were returned while fifty copies were not returned; the responses were categorized according to strongly agreed, agreed, strongly disagreed, disagreed and neutral with weight of (5,4,3,2,1) assigned to each category respectively to generate acceptable raw data for econometric analysis. The raw data were analyzed using cointegrated, ordinary least squares, autoregressive distributed lag, unit root and Grange causality; the result shows that POS has significant and positive impact on cashless policy in Nigeria. We therefore recommend that POS should be deployed to various areas to facilitates exchange transactions and ultimately reduces cash based related transactions in the economy.