530 research outputs found
On the Coexistence of Aperiodic and Periodic Traffic in Cellular Vehicle-to-Everything
Cellular Vehicle-to-Everything (C-V2X) communications are the key to connected and autonomous driving, and pave the way for future Intelligent Transport Systems (ITS). To support non-safety and safety critical applications in the demanding out-of-coverage scenario, the 3rd Generation Partnership Project (3GPP) has standardized the distributed C-V2X Mode 4 solution, whose behavior has been thoroughly analyzed for periodic traffic. In the current work, the problem of allocating aperiodic traffic in Mode 4 is tackled, a matter that has not been addressed before and that raises several challenging questions. A solution for serving such traffic type is put forth, and an analytical insight on the attainable performance is offered. Further, it is numerically proved that guaranteeing aperiodic flows good service levels is hard when their packets are not small sized. This holds true even for sophisticated physical layer choices and at relatively modest traffic densities, revealing that novel approaches to radio resource assignment are a necessity in Fifth Generation (5G) vehicular communications
Machine Learning for Disseminating Cooperative Awareness Messages in Cellular V2V Communications
This paper develops a novel Machine Learning
(ML)-based strategy to distribute aperiodic Cooperative Awareness Messages (CAMs) through cellular Vehicle-to-Vehicle (V2V)
communications. According to it, an ML algorithm is employed
by each vehicle to forecast its future CAM generation times;
then, the vehicle autonomously selects the radio resources for
message broadcasting on the basis of the forecast provided by
the algorithm. This action is combined with a wise analysis of
the radio resources available for transmission, that identifies
subchannels where collisions might occur, to avoid selecting them.
Extensive simulations show that the accuracy in the prediction
of the CAMs\u2019 temporal pattern is excellent. Exploiting this
knowledge in the strategy for radio resource assignment, and
carefully identifying idle resources, allows to outperform the
legacy LTE-V2X Mode 4 in all respects
Fundamental Limits on the Uplink Performance of the Dynamic-Ordered SIC Receiver
Due to the rapid and widespread growth of the Internet-of-Things (IoT) paradigm, present
days witness an exponential increase in the number of connected devices. In this regard, the orthogonal
transmission techniques featured by conventional 4G and 5G systems can only support a limited number of
simultaneously active users, due to their low spectral efficiency and poorly flexible resource allocation. To
overcome such limitations, the 6G framework will include novel Next Generation Multiple Access (NGMA)
solutions that will efficiently and flexibly connect a significantly larger number of devices over the same
portion of spectrum. Under the NGMA umbrella, the Power-Domain Non-Orthogonal Multiple Access
(PD-NOMA) technology is able to accommodate multiple users on the same frequencies by carefully
assigning different power levels to the active users and employing Successive Interference Cancellation
(SIC) receivers. In this work, we put forth a novel analytical approach to evaluate the performance that
PD-NOMA achieves on the uplink of a single cell when a dynamic-ordered SIC receiver is considered.
With respect to other existing works, the fundamental limits on the system performance are assessed
analytically for an arbitrary number = of simultaneously transmitting users, and both the case of Rayleigh
and lognormal-shadowed Rayleigh fading are examined. The closed-form expressions presented in this
work, whose correctness and excellent accuracy are validated through Monte Carlo simulations, disclose
the impact of lognormal shadowing and an increasingly larger number of active users on the PD-NOMA
performance
Zircon dissociation in air plasma through a low power transferred arc plasma torch
Thermal plasma dissociation offers a convenient and attractive route to prepare zirconium oxide from zircon mineral. Transferred and non-transferred arc plasma torches have been used to study zircon dissociation. The major thrust has been to accomplish complete dissociation and make the process simpler and cost effective. Technologically, this has been attempted in argon-fired plasma reactors using higher electrical power. The present work reports a cost effective low power transferred arc plasma (TAP) processing method for dissociating zircon by using air as the plasma forming gas. Phase composition and microstructure formation of the dissociated zircon were examined by XRD and SEM with EDX. Experimental results showed that the torch input power and processing time strongly influenced the dissociation percentage as well as the microstructure formation. Further, obtained results revealed that the air plasma medium significantly improved the percentage of zircon dissociation rather than argon plasma medium at 10 and 15 kW power levels. The air plasma gives complete zircon dissociation at 10 kW power with 5 min of processing
POLITICAL ELECTIONS FOR MARKETERS
SrFe12O19 coatings, intended as electromagnetic wave absorbers, were produced by atmospheric plasma spraying (APS) using two different kindsof feedstock powders: spray-dried agglomerates of micrometric SrFe12O19 particles (type-A) or spray-dried agglomerates of raw materials (SrCO3,Fe2O3), reactively sintered at 1100 ◦C (type-B).During spraying, type-A agglomerates either remain unmelted, producing porous coating regions where crystalline hexaferrite is retained, orare disrupted into smaller granules which melt completely, resulting in dense coating regions with no crystalline hexaferrite.The sintered type-B agglomerates possess higher cohesive strength and do not fall apart: the finer ones melt completely, whereas, in the largerones, the outer region melts and infiltrates the porous unmelted core which retains crystalline hexaferrite. Dense coatings can therefore be obtainedwhile preserving high amounts of crystalline hexaferrite even inside the dense areas. Such coatings show magnetic properties that are promisingfor electromagnetic wave absorption applications
Subjetividades femininas e políticas no documentário brasileiro: Petra Costa e Maria Augusta Ramos
Throughout the impeachment of former president Dilma Roussef, several Brazilian filmmakers recorded images of the movement in the streets and the political process that changed the country's image. Among these works, the documentaries by Maria Augusta Ramos, O Processo (2018) and Petra Costa, Democracia em Vertigem (2019), approaching the impeachment of President Dilma Roussef, the first woman to govern Brazil, from different narrative strategies, have gained prominence. In both, the protagonism is of women, women on stage and behind the cameras narrating the nation. These are films that rescue Brazilian narrative documentary traditions, combining elements of direct and indirect cinema. The objective of this article is to promote a comparative analysis between these works, and to reflect on their contribution to the Brazilian documentary tradition and to the political representation of genderA lo largo del proceso de destitución de la ex presidenta Dilma Roussef, varios cineastas brasileños grabaron imágenes del movimiento en las calles y del proceso político que cambió la imagen del país. Entre estos trabajos destacaron los documentales de Maria Augusta Ramos, O Processo (2018) y Petra Costa, Democracia em Vertigem (2019), que abordan el impeachment de la presidenta Dilma Roussef, la primera mujer en gobernar Brasil, desde diferentes estrategias narrativas. En ambos, el protagonismo es de las mujeres, mujeres en el escenario y detrás de las cámaras que narran la nación. Son películas que rescatan la tradición del documental narrativo brasileño, combinando elementos del cine directo e indirecto. El objetivo de este artículo es promover un análisis comparativo entre estas obras y reflexionar sobre su contribución a la tradición documental brasileña y a la representación política del género.Ao longo do impeachment da ex-presidenta Dilma Roussef, vários cineastas brasileiros gravaram imagens da movimentação nas ruas e do processo político que mudou a imagem do País. Dentre esses trabalhos ganharam destaque os documentários de Maria Augusta Ramos, O Processo (2018) e o de Petra Costa, Democracia em Vertigem (2019), abordando o impeachment da presidenta Dilma Roussef, primeira mulher a governar o Brasil, a partir de diferentes estratégias narrativas. Em ambos o protagonismo é das mulheres, são as mulheres em cena e por trás das câmeras narrando a nação. Trata-se de filmes que resgatam tradições documentais narrativas brasileiras, combinando elementos de cinema direto e indireto. O objetivo desse artigo é promover uma análise comparativa entre essas obras, e refletir sobre sua contribuição para a tradição documentária brasileira e para a representação política de gênero
Delitos e Transmidiação em “Rosario Tijeras”
A série televisiva colombiana “Rosario Tijeras”, baseada no livro e no filme de mesmo nome, narra a história de uma jovem que é abusada e violada na infância, e que se vinga de um de seus agressores, cortando seus testículos com uma tesoura. O feito faz Rosario se tornar famosa, e ser contratada como sicária pelos chefões do narcotráfico. O objetivo é analisar a existência de um processo de transmidiação, a partir da relação entre livro, filme e série televisiva, não como um modelo de produção, mas como uma expansão do universo diegético ancorada em estruturas de sentimentos (Williams, 1996) que são potencializadas pela esfera virtual. Esta abordagem adota a perspectiva dos estudos culturais (MITTELL, 2004), para discutir a classificação de narconovela, e dos gêneros televisivos, aqui compreendidos como categorias culturais
Na pista do crime: o policial argentino como gênero em Betibú
From 2010 to 2014, the Argentine crime movies experienced one of their most effervescent periods with “The Secret of their eyes” (2010), by Juan José Campanella, a Oscar winner, “Thesis on a Homicide” (2013), by Hernán Goldfrid, that got approval by audience and critics, and “Betibú” (2014), by Michel Cohen, a film that offers a new way of looking reality in the country. The criminal narrative in Argentina is linked to the literary tradition, and meets in Jorge Luís Borges and Bioy Casares strong advocates, on the one hand, by the other, to the development of the film industry since 1933 to 1942, highlighting “Fuera de la Ley” (1937) by Manuel Romero. The whodunit formula with a noir style is present in “Betibu” combining elements of crime genre and suspense thrillers, and criticizing media and life in global cities.Keywords: Crime Fiction; neonoir; neopolicial; Argentine Cinema; Brazilian CinemaEntre 2010 e 2014, o policial argentino viveu um de seus períodos mais efervescentes, com “O Segredo dos seus olhos” (2010), de Juan José Campanella, que conquistou um Oscar, “Tese sobre um homicídio” (2013), de Hernán Goldfrid, êxito de bilheteria e crítica, e “Betibú” (2014), de Michel Cohen, película que lança um novo olhar sobre o gênero e sobre a realidade do país. A narrativa policial na Argentina está ligada à tradição literária, que teve em Jorge Luís Borges e Bioy Casares fortes defensores, de um lado, e de outro ao desenvolvimento da indústria cinematográfica, entre 1933 a 1942, com destaque para “Fuera de la ley” (1937), de Manuel Romero. A trama de investigação com toque noir está presente em “Betibú”, que mescla elementos do gênero criminal e de suspense, e critica a mídia e a vida nas cidades globais.Palavras-chave: Ficção policial; neonoir; neopolicial; cinema argentino; cinema brasileiro
Development of matte finishes in electrostatic (EFB) and conventional hot dipping (CHDFB) fluidized bed coating process
This study focuses on the correlation between the thermo-rheological properties of a thermosetting powder coating system with its surface structure build-up. Epoxy powder coating systems, which displayed surface matting and surface wrinkling, were examined. Firstly, the evolution of the complex viscosity was correlated with the cure kinetic. Secondly, the structure build-up on the surface of the coatings was investigated with a combined SEM-CLA profilometry analysis at different stages of curing process for both EFB and CHDFB coating processes. Different finishes were found to characterize the films applied by using EFB and CHDFB coating processes as a result of the different way the film is heated by. Finally, a strict relationship of film morphology to the degree of conversion and to the evolution of the complex viscosity was found out for both EFB and CHDFB coating processes. The surface structure is built up after gelation point and continues to evolve after gelation with a full development of the film fine structure. Differences were observed in the surface structure build-up when different curing temperature was used, thereby indicating an influence of minimum viscosity on achievable finishing. These experimental results lead to further advances in a better understanding of the formation of surface topography and morphology of polymeric films. They also provide important indications for the settings of curing parameters in both EFB and CHDFB coating processes as well as for the development of new powder coating formulations. © 2007 Elsevier B.V. All rights reserved
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