Análise evolutiva da morfogênese funcional e tipológica urbana: o caso da rua comercial Santa Ifigênia em São Paulo

O artigo apresenta uma nova abordagem para a análise e compreensão do fenômeno de especialização de ruas comerciais, por meio da aplicação dos princípios teóricos evolutivos ao estudo urbano. A rua paulistana Santa Ifigênia, especializada no comércio varejista dos setoreseletro-eletrônicos e informática, tem servido como suporte da teoria no campo prático.The paper presents a new perspective in order to analyze and comprehend the specialization process of retail streets, through an application of theoretical evolutionary principles to urban study. The street Santa Ifigênia in São Paulo, specialized in electronic and computer retail products, is used as a study case of the theory

A Fast and Low-Complexity Operator for the Computation of the Arctangent of a Complex Number

[EN] The computation of the arctangent of a complex number, i.e., the atan2 function, is frequently needed in hardware systems that could profit from an optimized operator. In this brief, we present a novel method to compute the atan2 function and a hardware architecture for its implementation. The method is based on a first stage that performs a coarse approximation of the atan2 function and a second stage that improves the output accuracy by means of a lookup table. We present results for fixed-point implementations in a field-programmable gate array device, all of them guaranteeing last-bit accuracy, which provide an advantage in latency, speed, and use of resources, when compared with well-established fixed-point options.This work was supported by the Spanish Ministerio de Economia y Competitividad and FEDER under Grant TEC2015-70858-C2-2-R.Torres Carot, V.; Valls Coquillat, J. (2017). A Fast and Low-Complexity Operator for the Computation of the Arctangent of a Complex Number. IEEE Transactions on Very Large Scale Integration (VLSI) Systems. 25(9):2663-2667. https://doi.org/10.1109/TVLSI.2017.2700519S2663266725

Fast- and Low-Complexity atan2(a,b) Approximation

[EN] This article presents a new entry to the class of published algorithms for the fast computation of the arctangent of a complex number. Our method uses a look-up table (LUT) to reduce computational errors. We also show how to convert a large-sized LUT addressed by two variables to an equivalent-performance smaller-sized LUT addressed by only one variable. In addition, we demonstrate how and why the use of follow-on LUTs applied to other simple arctan algorithms produce unexpected and interesting results.This work is funded by the Spanish Ministerio de Economía y Competitividad and FEDER under grant TEC2015-70858-C2-2-R.Torres Carot, V.; Valls Coquillat, J.; Lyons, R. (2017). Fast- and Low-Complexity atan2(a,b) Approximation. IEEE Signal Processing Magazine. 34(6):164-169. https://doi.org/10.1109/MSP.2017.2730898S16416934

Terahertz Radiation Detection by Field Effect Transistor in Magnetic Field

We report on terahertz radiation detection with InGaAs/InAlAs Field Effect Transistors in quantizing magnetic field. The photovoltaic detection signal is investigated at 4.2 K as a function of the gate voltage and magnetic field. Oscillations analogous to the Shubnikov-de Haas oscillations, as well as their strong enhancement at the cyclotron resonance, are observed. The results are quantitatively described by a recent theory, showing that the detection is due to rectification of the terahertz radiation by plasma waves related nonlinearities in the gated part of the channel.Comment: 4 pages, 3 figure

Designing Human-friendly Cities

Designing human-friendly cities

Regeneration from within: formation and transformation of specialized retail streets in São Paulo (Brazil)

La propuesta tiene por objeto mostrar el proceso formativo de vías comerciales especializadas en São Paulo (Brasil), haciendo constar su naturaleza no planificada y las implicaciones del cambio funcional de las edificaciones originalmente residenciales a comerciales. Se evidencia cómo este característico modo de proceder está favorecido por factores tanto determinantes como contingentes, resultando en un proceso de regeneración urbana funcional y morfotipológico autoorganizado. Como consecuencia, la especialización comercial de vías opera gradualmente y en períodos relativamente largos —desde la aparición de una nueva área urbana—, pudiéndose constatar analogías de formación y transformación en el estudio comparativo aquí realizado. Nuestro trabajo ha levantado un total de 56 vías de comercio especializado en la ciudad de São Paulo, caracterizando la influencia que los condicionantes morfológicos, en su origen y cambio, han ejercido sobre la consolidación de usos comerciales y el tipo concreto de comercio minorista a que da lugar cada vía. Los usos comerciales tienen un papel determinante en la organización de centralidades en la ciudad y área metropolitana de São Paulo, condicionando las políticas públicas, especialmente de movilidad y espacio público, que deben considerarse para su promoción o conversión. El análisis concluirá con la discusión sobre cómo afecta a esta categoría de vías urbanas el nuevo instrumento de ordenación de usos comerciales propuesto en el ámbito de la Comunidad Valenciana (Plan de Acción Territorial Sectorial del Comercio de la Comunitat Valenciana, PATSECOVA), previsto para aprobación en los meses de abril o mayo

FPGA implementation of a 10 GS/s variable-length FFT for OFDM-based optical communication systems

[EN] The transmission rate in current passive optical networks can be increased by employing Orthogonal Frequency Division Multiplexing (OFDM) modulation. The computational kernel of this modulation is the fast Fourier transform (FFT) operator, which has to achieve a very high throughput in order to be used in optical networks. This paper presents the implementation in an FPGA device of a variable-length FFT that can be configured in run-time to compute different FFT lengths between 16 and 1024 points. The FFT reaches a throughput of 10 GS/s in a Virtex-7 485T-3 FPGA device and was used to implement a 20 Gb/s optical OFDM receiver. (C) 2018 Elsevier B.V. All rights reserved.This work was supported by the Spanish Ministerio de Economia y Competitividad under project TEC2015-70858-C2-2-R with FEDER funds.Bruno, JS.; Almenar Terre, V.; Valls Coquillat, J. (2019). FPGA implementation of a 10 GS/s variable-length FFT for OFDM-based optical communication systems. Microprocessors and Microsystems. 64:195-204. https://doi.org/10.1016/j.micpro.2018.12.002S1952046

Optimised CORDIC-based atan2 computation for FPGA implementations

This paper is a postprint of a paper submitted to and accepted for publication in Electronics Letters and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library[EN] A method for the implementation of the atan2 operator based on the coordinate rotation digital computer algorithm is described. In the proposal, the computation of the z-path takes advantage of the look-up table-based FPGA resources to reduce by between 17 and 25%, without performance deterioration, the overall area of the unrolled architecture.This work was funded by the Spanish Ministerio de Economia y Competitividad and FEDER under the grant TEC2015-70858-C2-2-R.Torres Carot, V.; Valls Coquillat, J.; Canet Subiela, MJ. (2017). Optimised CORDIC-based atan2 computation for FPGA implementations. Electronics Letters. 53(19):1296-1298. https://doi.org/10.1049/el.2017.2090S12961298531