bluuebunny/crossref_metadata_2025 huggingface dataset:
IDENTIDADE QUILOMBOLA: ATUAÇÕES NO COTIDIANO DE MULHERES QUILOMBOLAS NO AGRESTE DE ALAGOAS
Authors: Fernandes Saulo Luders , Galindo Dolores Cristina Gomes , Valencia Liliana Parra
Published: December 2020

O presente trabalho é parte de uma pesquisa de campo e caracteriza-se por um estudo de caso de caráter qualitativo exploratório, que teve por objetivo analisar a atuação da identidade quilombola no cotidiano de mulheres de um quilombo do agreste de Alagoas. A pesquisa foi realizada em quatro etapas sendo elas: 1- revisão bibliográfica; 2- inserção no campo de pesquisa; 3- coleta e análise das informações; 4- devolutiva da pesquisa às participantes e comunidade. As participantes da pesquisa foram três mulheres: uma jovem (20 anos), uma adulta (47 anos) e uma idosa (71 anos). Foram realizadas entrevistas semiestruturadas com dois temas: as vivências do cotidiano enquanto mulheres negras quilombolas; e os sentidos produzidos pelas entrevistadas sobre a identidade quilombola. Após transcritas, as entrevistas foram submetidas à análise de conteúdo que permitiu a produção de duas categorias temáticas: a) as vivências de opressão de mulheres negras quilombolas; b) diversidade de sentido sobre a identidade quilombola. As narrativas das mulheres permitiram compreender o quilombo como lugar de afirmação de seus modos de vida enquanto mulher negra, bem como o espaço de reprodução de lógicas de opressão frente à interseccionalidade dos marcadores étnico-raciais e de gênero. Houve também diferença geracional quanto ao modo de compreensão da identidade quilombola na vida da jovem e da idosa participante. Cabe compreender as especificidades com que cada comunidade e seus membros interpretam a identidade quilombola em seu viver e fazer, no entendimento que ela pode atuar como um potencializador na afirmação destes territórios negros.
SOBREVIVER NAS RUAS: PERCURSOS DE RESISTÊNCIA À NEGAÇÃO DO DIREITO À SAÚDE
Authors: Vale Aléxa Rodrigues do , Dalla Vecchia Marcelo
Published: December 2020

Contextos de exclusão conformam ciclos de marginalização de grupos populacionais, como a população em situação de rua (PSR). Nesse contexto violações de direitos humanos são recorrentes, em especial a dificuldade de acesso à saúde. A efetivação das políticas para a PSR nas cidades brasileiras ainda é escassa, por sua restrição a cidades de médio e grande porte e ao parco investimento público. Dessa forma, o estudo tem por objetivo investigar os percursos de cuidado à saúde da PSR em um município de pequeno porte. Foram realizadas observações de campo e entrevistas semiestruturadas para identificação e compreensão dos recursos acionados nas trajetórias de cuidado à saúde, que foram analisadas a partir da análise de conteúdo temática. Ressaltaram-se as diversas estratégias desenvolvidas pelo público diante da negação do direito à saúde e ao autocuidado. Destacam-se entre os resultados a precariedade de ofertas ao cuidado da saúde da mulher, a restrição do cuidado em saúde ao uso de substâncias psicoativas, de cunho medicalizante e centrado no paradigma da abstinência. Observou-se a importância da moradia para o cuidado integral, e das redes sociais e comunitárias como forma de restabelecimento da saúde nas ruas.
SYNTHESIS OF THE COMPOSITE CERAMIC MATERIAL AND INVESTIGATION OF ITS ABRASIVE PROPERTIES
Authors:   Tver State Technical University, BOLOTOV A.N. , NOVIKOVA O.O. ,   Tver State Technical University, NOVIKOV V.V. ,   Tver State Technical University
Published: December 2020

The innovative diamond-containing composite material formed by micro-arc oxidation on the surface of a sintered billet from a diamond-aluminum mixture has been developed. The method of the modification of the basic technology of a material obtaining has been proposed in order to reduce energy consumption and improve its frictional properties. The total time of material formation is reduced by replacing a part of the aluminum powder with white fused abrasive alumina powder, subsequent sintering and formation of diamond-ceramic material by micro-arc oxidation. It was found that the addition of corundum powder has a positive effect on the progress of the microarc oxidation process. A basic structural model of the new material has been developed. Friction tests have shown the advantage of diamond-containing materials of modified composition in comparison with the basic one. It is proposed to use the new material as a tool one for precision abrasive micro-processing of solid materials.
STUDY OF THE OPERATION OF THE SUCTION NOZZLE OF PEAT PNEUMATIC HARVESTER
Authors:   Tver State Technical University, YABLONEV А.L. , SCHERBAKOVA D.M. ,   Tver State Technical University
Published: December 2020

The extraction of milled peat by the pneumatic harvesting complex of machines has a number of advantages in contrast to the mechanical method. These advantages are as follows: the milling of wet peat deposits during harvesting is excluded, the range of required equi-pment is reduced, and the cycle time is shortened from two to one day. The latter is especially important, since two-day periods with good sunny weather in the production season are much less than one-day ones. Therefore, in general, the reliability of the method with pneumatic peat harvesting is higher. To evaluate the efficiency of the modern KTT-2 pneumatic harvesting machine, a field experiment was conducted to evaluate the suction speed of the nozzle of the machine. The results of the study made it possible to build the velocity field of the suction torch and determine the maximum suction speed – 26.74 m/s. The minimum air flow velocity in the studied zone is 0.3 m/s and is observed at a distance of 0.5 m from the nozzle. An analysis of the velocity field of the suction torch revealed the dependence of the air flow velocity on the distance from the nozzle. The size of the active zone of the suction plume has been identified and ways to optimize its size have been proposed.
EFFECT OF OPERATING PARAMETERS OF VERTICAL PNEUMATIC TRANSPORT OF CRUSHED PEAT ON RELATIVE SLIDING OF AIR AND SOLID PHASES
Authors:   Belarusian National Technical University, PETRENKO S.M. , BEREZOVSKY N.I. ,   Belarusian National Technical University
Published: December 2020

The actual operating parameters of the vertical pneumatic conveying of milled peat are determined by numerical methods on the grounds of the pressure differential in the pneumatic conveying pipeline section and flow rates known from experience. The assessment of the influence of the main operating parameters on the coefficient of relative slip of the air and solid phases is carried out.
Teachers Pedagogical Practices Vis-A-Vis Academic Achievement of SeniorHigh School Students in Ada East District, Ghana
Authors:   Department of Business and Social Sciences Education, University of Cape Coast, Ghana, Kporyi Ebenezer
Published: December 2020

The study sought to establish the relationship between teachers’ pedagogical practices and Senior High School (SHS) students’ academic achievement in Ada East District of the Greater Accra Region, Ghana. The cross-sectional survey research design was adopted for the study. The census method was used to select all the 126 teachers in the district while 126 students were also selected from a population of 1294 using the stratified proportionate and simple random sampling techniques. Four hypotheses were formulated to guide the study. Pearson Product Moment Correlation was used to test the first two hypotheses while Independent-Sample T-test and One-Way ANOVA were used to test the third and fourth hypotheses respectively. The result revealed that there was a statistically significant positive weak relationship between teachers’ competence in planning and preparation and students’ academic achievement. There was also a positive weak relationship between teachers’ pedagogical responsibilities and students’ academic achievement. Furthermore, both male and female teachers demonstrated similar pedagogical practices and finally the study established that significantly, the pedagogical practices of teachers statistically differed based on their teaching and professional qualification. Recommendations were made on how teachers could improve upon their pedagogical practices to enhance the academic achievements of their students.
Design solutions for interior architecture post coronavirus
Authors: Zaher Noha
Published: December 2020

The beginning of 2020 the Coronavirus spread threatened the whole world. The world's population forced to stay at homes - quarantine - to limit the spread of the epidemic. All our daily life practice became from home, this affect the interior spaces in shape, function and its impact on human physiological health. The research discuss the design solutions according to the instructions of world health organization from the view of interior designers and support the state’s plan innovation and development in fourth generation cities.

The priorities of the post-Coronavirus phase are to redesign environmental sustainable interior spaces for existing or new one. The research focus on the design solutions for the shared and public spaces, to get ready for the second wave of the epidemic and limiting its spread, by the usage of digital technologies that exploit our environmental resources and face the architectural design challenges in the future developments.
Hidden geographies of population implosion in Bosnia and Herzegovina
Authors:   University of Sarajevo, Bosnia and Herzegovina, GEKIC Haris , BIDZAN-GEKIC Aida ,   University of Sarajevo, Bosnia and Herzegovina, MIRIC Ranko ,   University of Sarajevo, Bosnia and Herzegovina, REMENYI Peter ,   University of Pécs, Hungary
Published: December 2020

Bosnia and Herzegovina has witnessed continuous depopulation since 1991. Depopulation was foreseen even without the emergence of war, but not nearly to that extent or that early. Bosnia and Herzegovina is in a worse demographic position than the European Union countries that show similar demographic trends. Very low birth rates, low fertility and low natural population growth have been recorded in the time of weaker economic development, which increasingly accelerates the emigration of the educated population in particular, and permanently adversely affects the reproductive potential of the country. This paper considers a hidden mutual relationship between the demographic situation (natural change, population ageing) in Bosnia and Herzegovina and its citizens' system of values. According to the survey conducted on 614 respondents, Bosnia and Herzegovina's citizens have fewer children than they would like.
Hidden black carbon air pollution in hilly rural areas—a case study of Dinaric depression
Authors:   University of Ljubljana, Slovenia, GLOJEK Kristina , GREGORIČ Asta ,   Aerosol d.o.o., Ljubljana, Slovenia, MOČNIK Griša ,   Jožef Štefan Institute, Slovenia, CUESTA-MOSQUERA Andrea ,   Leibniz Institute for Tropospheric Research, Germany, WIEDENSOHLER Alfred ,   Leibniz Institute for Tropospheric Research, Germany, DRINOVEC Luka ,   Jožef Štefan Institute, Slovenia, OGRIN Matej ,   University of Ljubljana, Slovenia
Published: December 2020

Air pollution is not an exclusively urban problem as wood burning is a widespread practice in rural areas. As we lack information on the air quality situation in rural mountainous regions, our aim is to examine equivalent black carbon (eBC) pollution in a typical rural karst area in the settlement of Loški Potok (Slovenia). eBC mass concentrations were measured by Aethalometer (AE-33) at two sites in Retje karst depression. The rural village station was located at the bottom of the karst depression whereas the rural background station was positioned at the top of the hill. We show the diurnal variation of equivalent black carbon mass concentrations for different seasons. In the populated karst depression, the major source of eBC pollution are households using wood as a heating fuel reaching the highest mass concentrations in winter. Diurnal pattern of eBC from biomass burning and traffic differ due to different source activity and it is influenced by typical formation of a cold air pool from late afternoon until late morning, restricting the dispersion of local emissions. The large difference in mass concentrations between the lowest part of the village (rural station) and the top of the hill (rural background station) indicates that in a vertically stratified and stable atmosphere local sources of black carbon have a major impact on air quality conditions in the area studied. Since in Alpine and Dinaric regions there are many similar inhabited areas, we can expect similar air quality conditions also in other rural hilly areas with limited self-cleaning air capacity.
Cirrus cloud shape detection by tomographic extinction retrievals from infrared limb emission sounder measurements
Authors: Ungermann Jörn , Bartolome Irene , Griessbach Sabine , Spang Reinhold , Rolf Christian , Krämer Martina , Höpfner Michael , Riese Martin
Published: December 2020

Abstract. An improved cloud-index-based method for the detection of clouds in limb sounder data is presented that exploits the spatial overlap of measurements to more precisely detect the location of (optically thin) clouds. A second method based on a tomographic extinction retrieval is also presented. Using CALIPSO data and a generic advanced infrared limb imaging instrument as examples for a synthetic study, the new cloud index method has a better horizontal resolution in comparison to the traditional cloud index and has a reduction of false positive cloud detection events by about 30 %. The results for the extinction retrieval even show an improvement of 60 %. In a second step, the extinction retrieval is applied to real 3-D measurements of the airborne Gimballed Limb Observer for Radiance Imaging in the Atmosphere (GLORIA) taken during the Wave-driven ISentropic Exchange (WISE) campaign to retrieve small-scale cirrus clouds with high spatial accuracy.
Sea ice feedbacks influence the isotopic signature of Greenland ice sheet elevation changes: last interglacial HadCM3 simulations
Authors: Malmierca-Vallet Irene , Sime Louise C. , Valdes Paul J. , Tindall Julia C.
Published: December 2020

Abstract. Changes in the Greenland ice sheet (GIS) affect global sea level. Greenland stable water isotope (δ18O) records from ice cores offer information on past changes in the surface of the GIS. Here, we use the isotope-enabled Hadley Centre Coupled Model version 3 (HadCM3) climate model to simulate a set of last interglacial (LIG) idealised GIS surface elevation change scenarios focusing on GIS ice core sites. We investigate how δ18O depends on the magnitude and sign of GIS elevation change and evaluate how the response is altered by sea ice changes. We find that modifying GIS elevation induces changes in Northern Hemisphere atmospheric circulation, sea ice and precipitation patterns. These climate feedbacks lead to ice-core-averaged isotopic lapse rates of 0.49 ‰ (100 m)−1 for the lowered GIS states and 0.29 ‰ (100 m)−1 for the enlarged GIS states. This is lower than the spatially derived Greenland lapse rates of 0.62–0.72 ‰ (100 m)−1. These results thus suggest non-linearities in the isotope–elevation relationship and have consequences for the interpretation of past elevation and climate changes across Greenland. In particular, our results suggest that winter sea ice changes may significantly influence isotope–elevation gradients: winter sea ice effect can decrease (increase) modelled core-averaged isotopic lapse rate values by about −19 % (and +28 %) for the lowered (enlarged) GIS states, respectively. The largest influence of sea ice on δ18O changes is found in coastal regions like the Camp Century site.
Vulnerability and Site Effects in Earthquake Disasters in Armenia
(Colombia). II – Observed Damages and Vulnerability
Authors: Chávez-García Francisco J. , Monsalve-Jaramillo Hugo , Vila-Ortega Joaquín
Published: December 2020

Abstract. Damage in Armenia, Colombia, for the 1999 (Mw6.2) event was disproportionate. We analyse the damage report as a function of number of storeys and construction age. We recovered two vulnerability evaluations made in Armenia in 1993 and in 2004. We compare the results of the 1993 evaluation with damages observed in 1999 and show that the vulnerability evaluation made in 1993 could have predicted the relative frequency of damage observed in 1999. Our results show that vulnerability of the building stock was the major factor behind damage observed in 1999. Moreover, it showed no significant reduction between 1999 and 2004.
Avalanche danger level characteristics from field observations of
snow instability
Authors: Schweizer Jürg , Mitterer Christoph , Reuter Benjamin , Techel Frank
Published: December 2020

Abstract. Avalanche danger levels are described in qualitative terms that mostly are not amenable to measurements or observations. However, estimating and improving forecast consistency and accuracy requires descriptors that can be observed or measured. Therefore, we aim to characterize the avalanche danger levels based on expert field observations of snow instability. We analyzed 589 field observations by experienced researchers and forecasters recorded mostly in the region of Davos (Switzerland) during 18 winter seasons (2001–2002 to 2018–2019). The data include a snow profile with a stability test (rutschblock, RB) and observations on snow surface quality, drifting snow, signs of instability and avalanche activity. In addition, observers provided their estimate of the local avalanche danger level. A snow stability class (very poor, poor, fair, good, very good) was assigned to each profile based on RB score, RB release type and snowpack characteristics. First, we describe some of the key snowpack characteristics of the data set. In most cases, the failure layer included persistent grain types, even after a recent snowfall. We then related snow instability data to the local avalanche danger level. For the danger levels 1–Low to 4–High, we derived typical stability distributions. The proportions of profiles rated poor and very poor clearly increased with increasing danger level. For our data set, the proportions were 5 %, 13 %, 49 % and 63 % for the danger levels 1–Low to 4–High, respectively. Furthermore, we related the local avalanche danger level to the occurrence of signs of instability such as whumpfs, shooting cracks and recent avalanches. The absence of signs of instability was most closely related to 1–Low, the presence to 3–Considerable. Adding the snow stability class and the 3-day sum of new snow depth improved the discrimination between the lower three danger levels. Still, 2–Moderate was not well described. Nevertheless, we propose some typical situations that approximately characterize each of the danger levels. Obviously, there is no single easily observable set of parameters that would allow fully characterizing the avalanche danger levels. One reason for this shortcoming is the fact that the snow instability data we analyzed usually lack information on spatial frequency, which is needed to reliably assess the danger level.
Fontcuberta, humorista y demiurgo: Mundos Alternativos Perfectamente Amueblados (MAPA)
Authors: Rodríguez Ferrándiz Raúl
Published: December 2020

En esta era de posverdad, fake news y deepfake (específica alteración digital fraudulenta de documentos audiovisuales) es necesario no solo reclamar el compromiso con la verdad del informador, sino la preservación de un espacio para la ficción que no sea estigmatizado. Las ficciones artísticas son territorios delicados que han de mantener su capacidad irrestricta de revelar mediante metáforas o ironías porciones de lo real, y al tiempo imaginar mundos alternativos que desearíamos visitar (o, al contrario, de los que abominaríamos). El texto que sigue repasa cronológicamente y analiza la obra de un excepcional creador de mundos a través de imágenes, Joan Fontcuberta, con la premisa de que cada una de sus colecciones es la metódica construcción de una porción de universo. En cuarenta años de incesante creación (y reflexión sobre ella), ha parodiado gran número de discursos: científico, periodístico, histórico, religioso, artístico  y  de  las  nuevas  tecnologías.  La  vía  para  conseguirlo era crear pequeños mundos y mostrarnos, con ironía, pruebas fotográficas de su existencia: fauna, flora, restos fósiles y aerolitos extraterrestres, constelaciones, accidentes geográficos y razas ignotas, astronautas y milagros, científicos y terroristas, noticiarios, periódicos, curadores de arte y artistas, incluso instituciones museísticas donde esas obras inventadas (doblemente) se expondrían. La suma de esos mundos parciales constituye un Mundo Alternativo Perfectamente Amueblado (MAPA), una cartografía casi tan completa y exigente en su coherencia interna como las que contenían la borgiana Enciclopedia de Tlön o las ficciones de Tolkien o George R. Martin.
Algunos conflictos de las imágenes en el marco del giro icónico. Esbozos de una ontología a partir de Paul Ricoeur
Authors: Gabriel Silvia
Published: December 2020

Luego de trazar tres posiciones respecto a los fenómenos icónicos y verbales, la linguocéntrica, la iconcéntrica y la dialéctica, y de vincularlas, respectivamente, con las tres corrientes de pensamiento imperantes en el giro icónico o pictorial, la semiótica, la perceptiva y la antropológica, buscaremos un concepto más o menos homogéneo de imagen. La imposibilidad de encontrar dicho concepto nos hará incursionar en el nivel performativo de las imágenes. Dada la dispersión en lo tocante a su poder o a su fuerza, la hipótesis es que, desde la filosofía, lo que puede servir como punto de encuentro es esbozar una ontología para las imágenes. En vista de ello, trazaremos una lectura y una interpretación de la filosofía hermenéutica de Paul Ricoeur. Concluiremos con una reflexión sobre los problemas y los límites de esta ontología.
Uma aproximação entre as políticas públicas de mobilidade urbana e os objetivos de desenvolvimento sustentável em Curitiba-PR
Authors: Locatelli Isabela Porte Vieira , Bernardinis Márcia De Andrade Pereira , Moraes Matheus Do Amaral
Published: December 2020

Objetivo: O presente estudo tem como objetivo verificar as inter-relações entre as principais políticas públicas de mobilidade urbana em Curitiba-PR e o Objetivo de Desenvolvimento Sustentável número 11 – Cidades e Comunidades Sustentáveis.Metodologia: Com fins exploratórios e apoiado nas categorias de análise propostas pelo IBAM (2016) – que permitem a classificação das políticas em termos de mais próximo ou mais distante – o estudo se deu por meio de pesquisa documental nos sites oficiais dos órgãos públicos.Originalidade/ Relevância: Tendo em vista a crise urbana enfrentada na mobilidade e a crescente produção de políticas públicas voltadas à problemática, análises relacionadas ao tema são cada vez mais urgentes. Principais resultados: Verificou-se que há correlação entre os conteúdos das políticas analisadas e o ODS 11. Os maiores níveis de inter-relação foram com as categorias de segurança viária e sustentabilidade, enquanto os menores foram com o transporte público e a acessibilidade.Contribuições: Nesse sentido, o presente estudo se insere justamente no esforço de estabelecer categorias de análise, com base nos parâmetros estabelecidos pelas metas presentes nos ODS, como elementos norteadores em um necessário processo de mensuração e avaliação das políticas públicas e suas dinâmicas.Conclusão: Conclui-se que é preciso um contínuo processo de mensuração e avaliação das políticas públicas. Nessa óptica, os aspectos qualitativos e o panorama dos itens pesquisados apontam indícios e tendências que podem ainda orientar novos estudos.
Athlete branding in less popular sport: a triadic approach
Authors: Hasaan Ali , Javani Vajiheh , Fişne Mücahit , Sato Shintaro
Published: December 2020

Objetivo do estudo: Apesar da existência de oportunidades de desenvolvimento de marcas dos atletas, em esportes menos populares os atletas encontram dificuldades neste tema. Portanto, o presente estudo teve como objetivo contribuir com a literatura existente sobre a marca do atleta, fornecendo uma compreensão melhor e holística da marca do atleta em esportes menos populares.Metodologia: Empregamos a abordagem triádica que envolveu três partes interessadas: Atleta, fãs e mídia, para explorar fatores importantes nas estratégias de marca do atleta em esportes menos populares..Originalidade/Relevância: Há menos foco no esporte menos popular e na marca de seus stakeholders. Com o crescente interesse dos fãs por esportes menos populares e seus atletas estão ganhando mais atenção do que nunca. Assim, o estudo optou por discutir um fenômeno ignorado no contexto da marca do atleta.Principais resultados: Os resultados identificaram quatro temas principais e oito subtemas associados com base nas entrevistas e na análise de conteúdo da mídia. Esses principais e subtemas incluem (1) desempenho (sucesso esportivo, nível de competição), (2) pessoal / privado (características fora do esporte, gerenciamento de imagem), (3) negócios / marketing (promoção de atleta, produtos mercadológicos) e (4) fator contextual (natureza esportiva, proximidade).Contribuições teóricas/metodológicas: o estudo atual contribuiu na literatura existente sobre a marca do atleta por meio do foco em um atleta importante de um esporte menos popular.
Developing Software Requirements Specification for a strategic goods air transportation system
Authors: Wojaczek Anna , Brown Michael Scott , Smal Tomasz
Published: December 2020

Management of air transportation of strategic goods is a very complex task with many challenges. This paper describes the method used in documenting the requirements for an IT system intended to support management of air transportation of military and dual-use goods. The work was completed in conjunction with a private logistics company. The project produced a Software Requirements Specification document and a working prototype. The document and prototype are held by the Military University of Land Forces of Poland.
Requirements were solicited from numerous sources. A private logistics company, numerous books and personal experience of the team members all contributed to requirements. These requirements were then analyzed and a final set of requirements was produced.
Screen mock-ups and a working prototype were developed. Selected screen shots are within the paper. The working prototype was developed by constructing a database and using a code generator to produce a web application.
CEVERO: A soft-error hardened SoC for aerospace applications
Authors: Silva Igor , Do Espírito Santo Otávio , do Nascimento Diego , Xavier-de-Souza Samuel
Published: December 2020

Radiation in the space environment poses a constant threat to circuit devices, and, as a solution, several fault tolerance techniques have been developed. However, some techniques use either proprietary technology or radiation-hardening specialized foundries to manufacture, either of which are not easily accessible to most researchers. There is, yet, another set of rad-hard techniques which provide sufficient fault tolerance to specific aerospace applications. The CEVERO SoC is a custom proofof-concept design that implements techniques as lockstep, dual module redundancy and state recovery in its inner fault tolerance module. It is meant to integrate with the open-source PULP platform and to open a path to a full fault-tolerant SoC.
“Un carácter verdaderamente mexicano”: “modelos de mundo”, historiografía y poscolonialismo en El Álbum mexicano (1849)
Authors: Ferrús Antón Beatriz
Published: December 2020

Este artículo analiza desde los parámetros teóricos y metodológicos de la críticacomo sabotaje El Álbum mexicano (1849), periódico ilustrado del siglo xix, que actuó como“sistema modelizante” para crear un relato de la nueva nación mexicana. Escritos geográficos,biografías, literatura, entre otros géneros, operaron en una misma dirección ideológica paradiseñar un mismo “modelo de mundo” inspirado en los ideales de la burguesía criolla.Asimismo, se establece un diálogo entre la crítica como sabotaje y el poscolonialismo con elque esta teoría dialoga de manera directa.
De la gran huelga literaria. Jacques Derrida y los desvíos del performativo
Authors: Valls Boix Juan Evaristo
Published: December 2020

El propósito del siguiente estudio consiste en analizar la performatividad de la literaturaen el pensamiento de Derrida y su potencial político para interrumpir procesos deconstitución de órdenes simbólicos (identidades, razas, géneros). La capacidad de la literaturapara “sabotear” la producción naturalizada de un orden a través de la operatividad del discursoradica en la particularidad de su fuerza performativa, que Derrida calificó en Force de loi como“fuerza de ruptura”, o como el derecho a la huelga en toda interpretación. En este sentido, laperformatividad de la literatura no consiste tanto en constituir como en destituir; no se tratatanto de colmar, como de holgar; no intenta producir o poner un mundo, sino deponerlo. Estareflexión sobre la fuerza desviada o destituyente de la literatura mostrará su carácter político,así como de su estrecha vinculación con la democracia: la apertura u hospitalidad que exigenambas es una permanente posibilidad de sabotaje y desinterpelación.
Research and application of plasma recoil pressure physical model for pulsed laser ablation material
Authors: Cai Song  , Chen Gen-Yu  , Zhou Cong  , Zhou Feng-Lin  , Li Guang  ,   School of Mechanical Engineering, Hunan University of Technology, Zhuzhou 412007, China;,   State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China
Published: December 2020

In this paper, the physical properties of plasma in the isothermal expansion process when material is ablated by pulsed laser is analyzed. It is shown that the recoil pressure distribution of the plasma near the material surface indicates an exponential decrease as the distance from the material surface increases and the recoil pressure distribution exhibits the characteristics of a Poisson distribution in the X direction; the recoil pressure distribution is in accordance with Maxwell's velocity distribution law in the Y direction; the recoil pressure distribution conforms to a Gaussian distribution in the Z direction. A three-dimensional plasma recoil pressure equation and the plasma kinetic equation for laser-ablation materials are studied. These equations only require parameters to relate to plasma temperature, laser parameters and material properties, thus having a certain diversity. The equations are used for numerically analyzing the pulsed laser ablation of a bronze-bonded diamond grinding wheel. The numerical analysis shows that in the X and Y direction the plasma expansion dimension shows linear growth. After the pulse is ended, the plasma expansion dimension values reach their maxima. The plasma expansion velocity shows nonlinear growth. After the pulse is ended, the expansion velocity first increases and then decreases along the X direction and Y direction. Based on the analyses of the plasma expansion dimension and the plasma expansion velocity, the maximum plasma recoil pressure appears at a location approximately 0.05 mm away from the surface of the grinding wheel after approximately 25 ns. Through calculating the Saha equation, the degree of ionization is 0.0012 at 7506 K, and the maximum plasma recoil pressure value is approximately 870 Pa. The experiments on the pulsed laser ablation of a bronze-bonded diamond grinding wheel under the corresponding conditions are conducted. A high-speed camera is used to observe splash phenomenon in the laser ablation process. A grating spectrometer is used to measure the plasma emission spectrum. According to the Boltzmann plot method, the electron temperature value is calculated to be 7506 K; according to the Stark broadening method, the electron density values range from 7.6451015 to 1.16081016 cm-3 and the recoil pressure values from 792 to 1203 Pa. The experiments show that the recoil pressure during the pulsed laser ablation of bronze-bonded diamond grinding wheel process can be ignored, and the correctness and feasibility of the plasma recoil pressure equation are also verified, which has heuristic significance for optimizing the laser ablation process.
Two-dimensional direction-of-arrival estimation of coherently distributed noncircular signals via symmetric shift invariance
Authors: Dai Zheng-Liang  , Cui Wei-Jia  , Ba Bin  , Zhang Yan-Kui  ,   The PLA Information Engineering University, Zhengzhou 450001, China
Published: December 2020

In practical applications such as mobile communication, radar and sonar, the effect of angular spread on the source energy can no longer be ignored due to multipath phenomena. Therefore, a spatially distributed source model is more realistic than the point source mode in these complex cases. A lot of direction-of-arrival (DOA) estimation methods for distributed sources have been published. Whereas researches concentrated on the complex circular signal case, the noncircular property of signal can be employed to further improve the estimation performance, which has received extensive attention recently. To date, several low-complexity DOA estimation algorithms for two-dimensional (2D) coherently distributed (CD) noncircular sources have been proposed. However, all these algorithms need obtain the approximate shift invariance relationship between the sub-arrays by applying the one-order Taylor series approximation to the generalized steering vectors, which may introduce additional errors and affect the estimation accuracy.
In this paper, a novel 2D DOA estimation algorithm based on the symmetric shift invariance relationship is proposed using the centro-symmetric three-dimensional (3D) linear arrays. Firstly, the extended array model is established by exploiting the noncircularity of the signal. Then, it is proved that the deterministic angular distribution function vector of the CD source has a symmetrical property for arbitrary centro-symmetric array, based on which the symmetric shift invariance relationships of extended generalized steering vectors are established in the three sub-arrays of 3D linear arrays. On the premise of such relationships, the center azimuth and elevation DOAs are obtained by the polynomial rooting method without spectral peak searching. Finally, the cost function implementing the parameter matching is constructed by the symmetric shift invariance relationship of the generalized steering vector of the whole array. Theoretical analysis and simulation experiment show that compared with the existing low-complexity algorithms, the proposed algorithm avoids the additional errors introduced by the Taylor series approximation, which allows it to achieve higher estimation accuracy with the small complexity cost. Moreover, the proposed algorithm can achieve omnidirectional angle estimation in the three-dimensional space.
Irradiation effect of Sm2Co17 type permanent magnets
Authors: Li Zhe-Fu  , Jia Yan-Yan  , Liu Ren-Duo  , Xu Yu-Hai  , Wang Guang-Hong  , Xia Xiao-Bin  ,   Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China
Published: December 2020

Insertion devices are crucial parts of the third generation of synchrotron radiation facility and free electron laser devices. The use of insertion device can improve the brightness and coherence of synchrotron radiation light. Undulator, one kind of insertion device, is largely installed in the storage ring of Shanghai synchrotron radiation facility. The main part of undulator is the device of magnetic source which consists of periodically arranged permanent magnets with the same magnetic field strength. In order to keep the normal electronic trajectory, a stable magnetic intensity in undulator is required. The Sm2Co17 type permanent magnets with high intrinsic coercive force and good radiation stability are largely installed in the facility. However, the losses for magnetic properties of Sm2Co17 type permanent magnets can be induced by longperiod irradiation in undulator through beam loss or mis-steering. The reduction of magnetic field could affect the electron energy, direction and the movement trajectory and so on, which seriously affects the amount of synchrotron radiation light. Microstructure of Sm2Co17 type permanent magnet affects the macro magnetic properties and there is not any available report on the microstructure investigation of Sm2Co17 type permanent magnet after being irradiated. Therefore, in this work, the effect of irradiation on the microstructure evolution is investigated. The radiation fields of Sm2Co17 type permanent magnets and the main particles (neutron) that result in losing magnetic properties are first analyzed and confirmed by Monte Carlo code FLUKA calculation. Then, Sm2Co17 type permanent magnet samples are irradiated by Ar ions at different fluences to simulate neutron irradiation damage. Meanwhile, the microstructure evolutions of irradiated samples are characterized by transmission electron microscopy. Moreover, high resolution transmission electron microscopic images are taken at the peak of radiation damage field to further investigate the radiation damage. In the respect of macro magnetic properties, hysteresis loops are measured by vibrating sample magnetometer in order to study the change of saturated magnetization. The results indicate that the decrease of saturated magnetization value is related to the change of microstructure, which proves the speculation of previous investigations. The evolution of 2:17 phase transformed from single crystals into amorphous structure is a possible microscopic mechanism for irreversible loss for saturated magnetization of Sm2Co17.
Effect of annealing treatment on characteristics of surface plasmon resonance for indium tin oxide
Authors: Jiang Hang  , Zhou Yu-Rong  , Liu Feng-Zhen  , Zhou Yu-Qin  ,   College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

With the development of modern micro-processing technology, the basic theory and relevant applications for surface plasmon have formed a new research direction which is known as surface plasmon photonics. The traditional plasmonic materials are noble metals, such as gold and silver, but they have some limitations that may hinder their application in plasmonic devices, such as lack of the chemical stability in air, difficulty in modulating by external field, large optical losses in the infrared wavelength range, etc. It has been demonstrated that transparent conducting oxides are a good candidate of plasmonic materials working in the infrared frequency range because of their low optical loss and tenability. Here in this work, the quasi-three dimensional silica nano-sphere array is prepared by nano-imprint lithography. Indium tin oxide (ITO) film is deposited on the array. The transmission properties are measured and the excitation modes of surface plasmons are analyzed for the samples obtained. Then, we focus on the effect of annealing treatment on characteristics of surface plasmon resonance for ITO thin films. The carrier concentration and carrier mobility of the ITO thin films annealed under different conditions are changed, and the corresponding surface plasmon resonance characteristics are investigated. The main results obtained in this work are as follows. 1) Mono-disperse SiO2 spheres, quasi-ordered monolayer SiO2 mask and ITO films with high transmittance ( 85%) and high electrical conductivity are obtained. Experimental results show that a surface plasma resonance at a wavelength of 1780 nm is excited for the glass/sphere/ITO system. 2) The grain size of ITO thin film after being annealed turns large, resulting in the increased optical transmittance of samples. 3) The carrier concentration of ITO film annealed in the air decreases, leading the resonance peak of surface plasmon to be red-shifted. 4) The carrier concentration of ITO thin film annealed in vacuum increases and the resonance peak is blue-shifted. These results obtained in this work contribute to the application of surface plasmon devices fabricated by ITO materials.
Photovoltaic effect in ferroelectrics
Authors: Cai Tian-Yi  , Ju Sheng  ,   School of Physical Science and Technology, Soochow University, Suzhou 215006, China
Published: December 2020

Ferroelectric oxides are attractive materials for constructing efficient solar cells. The mechanism includes the anomalous photovoltaic effect (APE) and the bulk photovoltaic effect (BPE). The BPE refers to the generation of a steady photocurrent and above-bandgap photovoltage in a single-phase homogeneous material lacking inversion symmetry. The mechanism of BPE is different from the typical p-n junction-based photovoltaic mechanism in heterogeneous materials. We survey the history, development and recent progress in understanding the mechanisms of BPE, with a focus on the shift current mechanism, an intrinsic BPE that is universal to all materials lacking inversion symmetry. We also review the important factors to the APE, i.e., the domain boundary, the Schottcky junction, and the depolarization field. The recent successful applications of inorganic and hybrid perovskite structured materials in solar cells emphasize that ferroelectrics can be used in conventional photovoltaic architectures. We review the development in this field, with a particular emphasis on the perovskite materials and the theoretical explanations. In addition to discussing the implication of a ferroelectric absorber layer and the solid state theory of polarization, the design principles and prospect for high-efficiency ferroelectric photovoltaics are also mentioned. Considering the coupling between the degrees of freedom, some special ferroelectrics are expected to have prominent multi-functionality. With the introduction of the additional degree of freedom, some ferroelectrics, i.e., ScFexCr1-xO3 (1/6 x 5/6), can be a promising candidate for highly efficient solar cells and spin photovoltaic devices.
Micro-perforated acoustic metamaterial with honeycomb-corrugation hybrid core for broadband low frequency sound absorption
Authors: Zhang Feng-Hui  , Tang Yu-Fan  , Xin Feng-Xian  , Lu Tian-Jian  ,   1. State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an 710049, China;,   2. MOE Key Laboratory for Multifunctional Materials and Structures, Xi'an Jiaotong University, Xi'an 710049, China;,   3. State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

A novel acoustic metamaterial is proposed by making micro-perforations on both the top facesheet and the corrugate plates of sandwich plate with honeycomb-corrugation hybrid core. The hybrid-cored metamaterial is ultra-lightweight, occupies a small volume, and exhibits excellent mechanical properties and good low-frequency sound absorption property. Based on the classical Maa theory of thin plates with micro-perforations, a theoretical model of sound absorption is established for the proposed metamaterial. The method of finite elements is subsequently used to validate the model, showing that their good agreement is achieved. Physical mechanism behind the energy dissipation in each sub-structure of the metamaterial is explored. It is found that the main route of energy dissipation is via viscous effect at the micro-perforation, and thermal dissipation is negligible. The influence of key geometrical parameters, such as upper facesheet thickness, perforation diameter and corrugated plate thickness, on sound absorption is systematically investigated. The present results are helpful for designing multifunctional lightweight materials/structures for simultaneous load-bearing, energy absorption and noise control.
Magnetic dynamic properties of defective iron nanorings
Authors: Ye Qing-Ying , Wang Wen-Jing , Deng Chu-Chu , Chen Shui-Yuan , Zhang Xin-Yuan , Wang Ya-Jing , Huang Qiu-Yi , Huang Zhi-Gao ,   College of Physics and Energy, Fujian Normal University, Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials, Fuzhou 350117, China,   Fujian Provincial Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen 361005, China
Published: December 2020

Magnetic nanorings can be high-density integrated because their stray field is low in vortex states. In this paper, the magnetic dynamic properties of the defective Fe nanorings are studied. For convenience, we assume the defect to be round in shape, whose coordinate is (0, Y). Based on the Monte Carlo method and fast Fourier transformation micromagnetism method, the magnetic properties of the defective Fe nanorings, such as hysteresis loops, spin configurations, remanence, etc., are studied. The simulation results indicate that the magnetization process of the system can be affected by the sizes and locations of the defects. When the defects are small, the system has a bistable state, which is similar to the system without defects. The transition state of the system increases as the defects are enlarged, and the bistable state will be no longer so visible. The system becomes open when the defects are big enough. Meanwhile, its hysteresis loop presents a rectangular shape which is similar to cluster’s or quantum dot’s. The remanence increases with the radius of defect increasing. These results are in accord with the magnetic properties of asymmetric magnetic nanoring. In order to explain the above results, the spin configurations of the system are shown. The spins of defective nanorings are divided into two parts, i.e., upper half part and lower half part, which are represented as blue and black spins respectively. When the system does not have any defects, the number of blue spins is equal to black spins’. Therefore the remanence is zero when the system is in a vortex state. It is found that the number of blue spins decreases as the radius of defect increases. This situation results in the total magnetic moment increasing, which leads the remanence to increase. However, the relationship between remanence and Y (the distance between center of nanoring and center of defect) is nonlinear. The remanence first increases and then decreases with Y increasing. The simulation results can be explained by changing the spin configuration. By analyzing the spins of the upper and lower part, the magnetic moment of the system is analyzed. It is found that the number of the spins and the local vortexes can affect the remanence significantly. The results show that the magnetic properties of Fe nanorings can be affected by the defect.
Mechanism of interaction between interface and radiation defects in metal
Authors: Liu Si-Mian , Han Wei-Zhong ,   Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

High-energy particles’ radiation produces a large number of radiation defects in material, such as interstitial atoms, vacancies, dislocation loops, voids and helium bubbles. The formation and evolution of massive radiation defects cause the instability of microstructure in metal, which further degrades its mechanical performance. Interface engineering is an effective method to tune the radiation resistance of metal and alloy. By introducing a large number of grain boundaries, phase interfaces, free surfaces, etc., the recombination probability of radiation-induced vacancies and interstitial atoms increases, thereby reducing the accumulation of radiation defects, improving the structural stability of the metal and eliminating the harmful effects of radiation. In this paper, we briefly review the recent progress of the mechanisms of interactions between several typical interfaces and various types of irradiation defects. The influence of interface structure, irradiation condition and defect character on their interaction behavior are reviewed and discussed. We also propose some critical questions about the radiation damage to material which remain to be understood. It is necessary to combine multidisciplinary techniques, knowledge and theories in order to fully understand the mechanism of radiation damage and design the advanced radiation-tolerant materials.