.: Resenha

Fagundes, Guilherme Moura. 2017. Outro fogo. Brasília, DF, Brazil, color, 21’, digital format. Accessed October 10, 2019. https://vimeo.com/313635468 Esta resenha do filme Outro fogo (2017), de Guilherme Moura Fagundes, leva em consideração o ponto de vista do autor como espectador privilegiado, desde as imagens na tela até a experiência sensorial e narrativa construída ao longo do filme. Nos deparamos com uma questão: o que é o medo? Ao longo da narrativa nos confrontamos com ambientes em chamas e práticas sociotécnicas de manejo do fogo, colocando questões para nós mesmos acerca de nossos sentimentos e práticas em relação ao meio ambiente. Somos convidados a experienciar este outro fogo, diferente daquele que destrói as matas, através da narrativa fílmica construída pelo autor.Fagundes, Guilherme Moura. 2017. Outro fogo. Brasília, DF, Brazil, color, 21’, digital format. Accessed October 10, 2019. https://vimeo.com/313635468 This review of Guilherme Moura Fagundes’s film Other Fire (2017), is based on a perspective that considers the author’s viewpoint as a privileged viewer, from the images on screen to the sensory and narrative experience built throughout the film. We are faced with a question: what is fear? The narrative presents us with burning environments and sociotechnical fire management practices over its course, questioning us about our feelings and practices regarding the environment

Manipulability in trajectory tracking for constrained redundant manipulators via sequential quadratic programming

Trajectory tracking methods for constrained redundant manipulators are presented in this thesis, where the end-effector of a redundant serial manipulator has to track a desired trajectory while some points on its kinematic chain satisfy one or more constraints. In addition, two manipulability indexes are taken into account in order to optimize the trajectory. The first index is defined in terms of the geometric Jacobian of the manipulator in the constrained configuration. The second index is based on the constrained Jacobian, which maps velocities from joint space to task space, taking into account the holonomic constraints. Three methods for solving the trajectory tracking problem are discussed. The first two, kinematic control (KC) and quadratic programming (QP), are widely discussed in literature. The third, sequential quadratic programming (SQP), is a new approach, unlike KC or QP, has as advantages (despite some shortcomings) not explicitly depend on pseudoinverse Jacobian, derivative from the desired trajectory and linearization of indexes or constraints. A discussion of these three methods is presented in terms of tracking error, constraint violation, singularity distance, among others through experiments performed on a Baxter collaborative robot.Métodos de rastreamento de trajetória para manipuladores redundantes restritos são apresentados nesta tese, onde o efetuador de um manipulador serial redundante tem que rastrear uma trajetória desejada enquanto alguns pontos em sua cadeia cinemática satisfazem uma ou mais restrições. Além disso, dois índices de manipulabilidade são levados em consideração a fim de otimizar a trajetória para evitar singularidades. O primeiro índice é definido em função do jacobiano geométrico do manipulador na configuração restrita. O segundo índice é baseado no Jacobiano restrito, o qual mapeia velocidades no espaço das juntas para a espaço da tarefa, levando em conta as restrições holonômicas. Três métodos para resolver o problema de rastreamento de trajetória são discutidos. Os dois primeiros, controle cinemático e programação quadrática (QP), são amplamente discutidos na literatura. O terceiro, programação quadrática sequencial (SQP), é uma nova abordagem, diferentemente do controle cinemático ou QP, tem como vantagens (apesar de algumas deficiências) não depender explicitamente da pseudo-inversa de jacobianos, derivadas da trajetória desejada e linearização de índices ou restrições. Uma discussão desses três métodos é apresentada em termos de erro de rastreamento, violação da restrição, distância de singularidades, entre outros através de experimentos realizados em um robô colaborativo Baxter

A baseband wireless spectrum hypervisor for multiplexing concurrent OFDM signals

The next generation of wireless and mobile networks will have to handle a significant increase in traffic load compared to the current ones. This situation calls for novel ways to increase the spectral efficiency. Therefore, in this paper, we propose a wireless spectrum hypervisor architecture that abstracts a radio frequency (RF) front-end into a configurable number of virtual RF front ends. The proposed architecture has the ability to enable flexible spectrum access in existing wireless and mobile networks, which is a challenging task due to the limited spectrum programmability, i.e., the capability a system has to change the spectral properties of a given signal to fit an arbitrary frequency allocation. The proposed architecture is a non-intrusive and highly optimized wireless hypervisor that multiplexes the signals of several different and concurrent multi-carrier-based radio access technologies with numerologies that are multiple integers of one another, which are also referred in our work as radio access technologies with correlated numerology. For example, the proposed architecture can multiplex the signals of several Wi-Fi access points, several LTE base stations, several WiMAX base stations, etc. As it able to multiplex the signals of radio access technologies with correlated numerology, it can, for instance, multiplex the signals of LTE, 5G-NR and NB-IoT base stations. It abstracts a radio frequency front-end into a configurable number of virtual RF front ends, making it possible for such different technologies to share the same RF front-end and consequently reduce the costs and increasing the spectral efficiency by employing densification, once several networks share the same infrastructure or by dynamically accessing free chunks of spectrum. Therefore, the main goal of the proposed approach is to improve spectral efficiency by efficiently using vacant gaps in congested spectrum bandwidths or adopting network densification through infrastructure sharing. We demonstrate mathematically how our proposed approach works and present several simulation results proving its functionality and efficiency. Additionally, we designed and implemented an open-source and free proof of concept prototype of the proposed architecture, which can be used by researchers and developers to run experiments or extend the concept to other applications. We present several experimental results used to validate the proposed prototype. We demonstrate that the prototype can easily handle up to 12 concurrent physical layers

On the distribution of an effective channel estimator for multi-cell massive MIMO

Accurate channel estimation is of utmost importance for massive MIMO systems to provide significant improvements in spectral and energy efficiency. In this work, we present a study on the distribution of a simple but yet effective and practical channel estimator for multi-cell massive MIMO systems suffering from pilot-contamination. The proposed channel estimator performs well under moderate to aggressive pilot contamination scenarios without previous knowledge of the inter-cell large-scale channel coefficients and noise power, asymptotically approximating the performance of the linear MMSE estimator as the number of antennas increases. We prove that the distribution of the proposed channel estimator can be accurately approximated by the circularly-symmetric complex normal distribution, when the number of antennas, M, deployed at the base station is greater than 10

ABC do Açude: Uma poesia contra o Estado

Durante a década de 1930, o nordeste brasileiro foi assolado por uma das maiores secas já registradas. O governo federal iniciou então, uma empreitada para a construção de imensos reservatórios artificiais de água denominados açudes. Durante a construção de um desses açudes no município de Macaúbas, na Bahia, certo tipo de poesia em forma de ABC foi criada e era declamada pelos trabalhadores da obra. Tal produção conta a trajetória dos operários na construção da barragem e faz algumas denúncias acerca de suas condições insalubres de trabalho. É partindo disso que esta pesquisa objetiva investigar, por um viés antropológico, a produção da vida e do conhecimento coletivo a partir da percepção e da relação com o meio em que se vive, bem como a constituição de um imaginário e de uma memória em torno desse meio e de suas modificações ao longo do tempo a partir da ação de políticas de gestão e controle da natureza e de sua própria forma física, o semiárido brasileiro

An Efficient FPGA-Based Frequency Shifter for LTE/LTE-A Systems

The Physical Random Access Channel plays an important role in LTE and LTE-A systems. Through this channel, the user equipment aligns its uplink transmissions to the eNodeB’s uplink and gains access to the network. One of the initial operations executed by the receiver at eNodeB side is the translation of the channel’s signal back to base-band. This operation is a necessary step for preamble detection and can be executed through a time-domain frequency-shift operation. Therefore, in this paper, we present the hardware architecture and design details of an optimised and configurable FPGA-based time-domain frequency shifter. The proposed architecture is based on a customised Numerically Controlled Oscillator that is employed for creating complex exponential samples using only plain logical resources. The main advantage of the proposed architecture is that it completely removes the necessity of saving in memory a huge number of long complex exponentials by making use of a Look-Up Table and exploiting the quarter-wave symmetry of the basis waveform. The results demonstrate that the proposed architecture provides high Spurious Free Dynamic Range signals employing only a minimal number of FPGA resources. Additionally, the proposed architecture presents spur-suppression ranging from 62.13 to 153.58 dB without employing any correction

ABC do Açude: Percepção, Imaginário e Memória no sertão

Introdução Na segunda metade de 2016, enquanto estudava o tema da relação entre as categorias natureza e cultura na antropologia nas reuniões do VISURB , como uma feliz coincidência, chegou em minhas mãos - através de um tio que atua como padre em pequenos municípios na Bahia - a transcrição de uma poesia oral que conta a história da construção de um açude em um distrito do município baiano de Macaúbas, localizado no interior do sul da Bahia, da perspectiva dos trabalhadores da obra. Suscitad..

A new species, new synonymy, and notes on Paravelia Breddin (Hemiptera: Heteroptera: Veliidae)

The broad-shouldered water strider Paravelia cunhai sp. nov. is described and illustrated based on material from the state of Pará, northern Brazil. The new species can be distinguished from all other species in this genus mainly by the dark color of the head and pronotum, absence of pruinosity or silvery pubescence on the anterior lobe of pronotum, maculae pattern on the fore wings, hind femur with row of 22 spines on mesal margin, and general shape of the paramere. This new species was collected in a pool inside a cave without incident light, a habitat recorded for the genus only recently, which reinforces the hypothesis that some species of Paravelia have troglophilic habits. In addition, a photograph of the dorsal habitus and notes concerning P. juruana Polhemus & Polhemus are provided, and P. cupariana Polhemus & Polhemus syn. nov. is proposed as a junior synonym of P. spinifera Polhemus & Polhemus

The Whole World as Strange Place

In The Whole World as Strange Place, an essay-like work, Canclini approachesmany cultural aspects of the contemporaneity in times of social decomposition. The structures that we believed to be stable and the theories we considered to explain the social realities no longer stand in a world in which actors are connected to socio technical networks and are creating and recreating their forms of association. In the book, the author crosses the world like a strange place, throwing itself in a "fly down" on subjects like: being foreign; the democracy, that in his concern gains the adjective "scoundrel"; forms of hacktivism; ways of writing science and literature; in addition to talking about academic congresses, always from a critical point of view regarding dominant Western culture and magisterial certainties.Em O Mundo Inteiro Como Lugar Estranho, livro de caráter ensaístico, Cancliniaborda diversos aspectos culturais da contemporaneidade em tempos de decomposição social. As estruturas que acreditávamos estáveis e as teorias que considerávamos como explicativas das realidades sociais já não se sustentam num mundo em que os atores ligados às redes sociotécnicas criam e recriam a todo instante suas formas de associação. No livro, o autor percorre este mundo como um lugar estranho, lançando-se num “voo baixo” sobre temas como: ser estrangeiro; a democracia que, a seus olhos, ganha o adjetivo de “canalha”; formas de hacktivismo; maneiras de escrever ciência e literatura; além de falar sobre os congressos acadêmicos, sempre de um ponto de vista crítico em relação a cultura ocidental dominante e às certezas magistrais