O desenvolvimento de um sistema computacional de sumarização multidocumento com base em um método linguisticamente motivado

This paper presents the studies conducted in the area of Natural Language Processing, more specifically, in Automatic Multi-document Summarization. We describe the steps for the production of a computational prototype, based on a linguistically motivated method, for summarizing news texts in Portuguese.Este trabalho apresenta os estudos realizados na área de Processamento de Linguagem Natural, mais especificamente, em Sumarização Automática Multidocumento. São descritos os passos para a produção de um protótipo computacional, baseado em um método linguisticamente motivado, para a produção de sumários de notícias jornalísticas escritas em português.FAPESPICMCPró-reitoria de Pesquis

Computer-Aided Large-Signal Measurement of IMPATT - Diode Electronic Admittance

A technique for the measurement of the large-signal electronic admittance of IMPATT’ diodes as a function of frequency and RF voltage level using the network analyzer is described. The method de-embeds the admittance of the active region of the device from the mounting and measurement circuitry without physical disturbance of the diode. The small series resistance of the diode at breakdown is included in the embedding network together with the mount and diode package parameters, The determination of transformation networks between the me

A comprehensive design method for dual-gate MOSFET mixers

A comprehensive design method for a dual-gate MOSFET (DGFET) mixer is proposed which provides a practical procedure to predict both the conversion gain and input compression point and to identify optimal bias conditions and local oscillator (LO) power level. Each step in the process can be implemented by either simulation or experimental methods and is suitable for both up-conversion or down-conversion. The technique is aimed at producing a well engineered design, not a rigorous numerical solution. Using a discrete packaged device, a single-balanced DGFET down-converter mixer circuit is designed and characterized using an RF input frequency of 857 MHz, LO frequency of 694 MHz, and an IF output frequency of 163 MHz

Microwave characterization of optically sensitive polymer and application to a tunable antenna

This paper investigates the use of a photoconductive polymer to optically tune a microwave device or antenna. The dielectric properties of a composite (Polymer + Cadmium Sulphide) photoconductive polymer are extracted using microwave reflection measurements on a coplanar waveguide test structure. The material under test was overlaid on an interdigitated capacitor that was fabricated on a transparent glass substrate. The material characterization was done with and without broadband optical illumination. The results obtained from the characterization show that the polymer was photoconductive. An extracted dielectric constant (ε r) of 4 and loss tangent (tanδ) of 0.004 were obtained without illumination, while the loss tangent increased to 0.11 with illumination and the ε r value had no measureable change. The properties of the novel photoconductive polymer were used in the theoretical design of an optically tunable dipole antenna for the GSM band (1900 to 2100 MHz). Tunability was achieved by applying the characterized polymer to a slotted segment of the dipole arm, and effectively changing the dipole length by optical illumination. Index Terms: composite/hybrid polymer, inter-digitated capacitor, optical control, RF agile antenna

The Field-Programmable Microwave Substrate

A novel low-loss programmable microwave waveguide is demonstrated. The waveguide is developed for applications in field-programmable microwave circuits with similar levels of programmability as that seen in field-programmable gate arrays. The waveguide is realized with a field-programmable microwave substrate (FPMS). The substrate consists of small unit cells that can be individually reconfigured to have a range of positive dielectric constants or a negative dielectric constant. The substrate is contained in a metal parallel plate structure. Programming a positive material sandwiched between two negative material sidewalls results in a waveguide that behaves in a way that is described by the slab waveguide equations. Miniaturization and increased density of unit cells can result in lower loss and better performance. Two implementations of the FPMS are presented. One implementation is on FR4 using all industry standard processes and components. The other implementation uses low-temperature cofired ceramic and custom designed CMOS chips. The FR4 implementation is used to demonstrate programmable waveguides, amplifiers, and oscillators from 0.9 to 3 GHz. The LTCC implementation is used to demonstrate miniaturization of the FPMS. The proposed FPMS concept promises a new era of programmable microwave circuit design for cognitive radio, the Internet of things, and self-healing/adaptive systems

Recent Advances in Broad-Band VHF and UHF Transmission Line Methods for Moisture Content and Dielectric Constant Measurement

Recent advances in VHF and UHF transmission line methods for determining either the complex permittivity or moisture content of bulky or film-like materials, or the thickness of film-like materials are discussed. These methods include TDR, CW phase, and |S21| transmission methods and employ a time-domain reflectometer (TDR), a vector voltmeter, and a network analyzer, respectively. Each technique involves monitoring the change of the transmission line parameters of a balanced open line, or of an unbalanced coaxial transmission line, when loaded with the material under test. Particular attention is given to the frequency range 10 to 1000 MHz and to broad-band methods. Experimental results are presented for several common materials, viz, concrete, asphalt, Plexiglas, moist paper, and moist soil. Copyrigh

Interboard optical data distribution by Bessel beam shadowing

We describe the efficient conversion of light from a laser diode into a Bessel beam whose axial intensity varies almost uniformly with distance using only a holographic optical element. An interesting shadowing property of the Bessel beam is demonstrated where on blocking the intense central spot the propagating ring pattern acts to reform the central spot a short distance following the obstruction. This behaviour together with the long propagation range for the Bessel beam's central spot are considered for multiboard optical interconnects