Brazilian Army Technological Center

Rio de Janeiro, Brazil

Brazilian Army Technological Center

Rio de Janeiro, Brazil
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Pralon L.,Brazilian Army Technological Center | Beltrao G.,Brazilian Army Technological Center | Pompeo B.,Brazilian Army Technological Center | Pralon M.,Brazilian Army Technological Center | Fortes J.M.,Pontifical Catholic University of Rio Grande do Sul
2017 IEEE Radar Conference, RadarConf 2017 | Year: 2017

Noise radar is an emerging technology which employs random signals as their transmit waveforms. Relying on its stochastic properties, with the proper choice of system s parameters, high performance with respect to the suppression of range ambiguity and low range sidelobes can be achieved. Many works have been published in the literature addressing systems that transmit carriers modulated in amplitude by a given stochastic process, generally generated by a hardware noise source. Nevertheless, the characterization of random frequency modulation (more suitable for several applications) is still an on going subject matter. Within this context, in this paper closed form expressions of the narrowband ambiguity function of random frequency modulated signals are presented, and, as a consequence, its Doppler tolerance is better addressed. © 2017 IEEE.

Bittencourt T.D.M.G.,Brazilian Army Technological Center | Gonzaga A.,University of Sao Paulo
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

The digital image processing of uncooled LWIR thermal detectors is one of the main steps in the research and development of thermal cameras. The study of this technology is a strategic issue for military and civil areas, considering that thermal imaging equipment have dual application. This paper aims to design and develop a pipeline of all processing steps required to obtain high performance images with low noise and high contrast. In addition to the digital processing algorithms, this paper presents some results of electro-optical characterization on the assembled system, indicating the main figures of merit that guide the study of this technology. © 2012 SPIE.

Pereira I.M.,Brazilian Army Technological Center | Pereira I.M.,Federal University of Minas Gerais | Pereira I.M.,Ghent University | Axisa F.,Ghent University | And 3 more authors.
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2011

In this work, we propose the use of shape-memory polymer as an anchoring system for a bladder sensor. The anchoring system was designed from a biomedical biodegradable water-based poly(ester-urethane) produced in an aqueous environment by using isophorone diisocyanate/hydrazine (hard segment) and poly(caprolactone diol)/2,2-bis (hydroxymethyl) propionic acid (soft segment) as the main reagents. Tensile strength and elongation-at-break deterioration upon degradation in synthetic urine were investigated. In-body shape recovery was simulated and measured in synthetic urine. Results indicated that shape recovery can occur at body temperature and expulsion of the sensor by the body along with urine may occur through the combined effect of urine hydrolytic attack and compression exerted by the bladder walls. © 2010 Wiley Periodicals, Inc.

de Sa L.B.,Brazilian Army Technological Center | Dias M.H.C.,Military Institute of Engineering of Rio de Janeiro | de Mesquita Filho A.C.,Federal University of Rio de Janeiro
Circuits, Systems, and Signal Processing | Year: 2016

Whereas the present practice of designing matching networks for antennas is limited to conventional topologies, requiring a significant amount of domain knowledge, evolutionary algorithms can be used for automatically identifying unconventional designs that are more effective than would otherwise be developed. In this work, an automatic method to design lossless matching networks driven by an evolutionary algorithm (EA) that considers the sensitivities of the network parameters during the synthesis process is presented. To this end, a closed-form expression for the transducer power gain (TPG) sensitivity with respect to the component values is employed in such a way that the effects of the components tolerance on the matching network performance can easily be quantified. A 3D data structure based on the adjacency matrix is conveniently used to represent any type of network topologies. The proposed EA employs a novel set of topology variation operators, tailored for changing the circuit topology, and an association step, with the aim of reducing the number of nodes of the matching circuit. The efficiency of the proposed EA is tested in the synthesis of an impedance matching network for a VHF monopole whip antenna. This study’s results indicate a matching bandwidth improvement, a more uniformly distributed TPG along the operation frequency band and a more stable TPG regarding the components tolerance compared to the results obtained by previous approaches. © 2016, Springer Science+Business Media New York.

Fonseca G.S.,Brazilian Army Technological Center | De Sa L.B.,Brazilian Army Technological Center | Mesquita A.C.,Federal University of Rio de Janeiro
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

The electric simulation models of CMOS devices provided by the foundries are valid at the standard temperature range of-55 to 125°C. These models are not suitable to the design of circuits intended to operate at cryogenic temperatures as is the case of cooled infrared readout circuits. To generate a library of CMOS electric simulation models valid at cryogenic temperatures, the characterization of wide and long CMOS transistors are investigated. The EKV2.6 model, which is an industry-standard compact simulation model for CMOS transistors, is used in this characterization. Due to its relatively small number of parameters the EKV2.6 model is well suited to the parameter extraction procedures when not disposing of an expensive automated parameter extraction system. It is shown that to provide an appropriate IV-characteristic fit to cryogenic temperature range it is sufficient to extract only five parameters-threshold voltage VT0, body effect GAMMA, Fermi potential PHI, transconductance factor KP, and the vertical characteristic field for mobility reduction E0. The proposed approach is tested in a standard 0.35μm/3.3V CMOS technology, employing extraction procedures recommended in the literature. Simulations are made with a BSIM3V3 standard library provided by the foundry changing the temperature parameter and with the generated library. The results are compared with the measurements. As expected, the simulations made with the generated library show a best agreement with the performed measurements at 77K than the simulations with the BSIM3V3 model. The proposed methodology is shown to be particularly effective above strong freeze-out temperature. © 2016 SPIE.

Pralon L.,Grenoble Institute of Technology | Pompeo B.,Brazilian Army Technological Center | Fortes J.M.,Pontifical Catholic University of Rio de Janeiro
IEEE Transactions on Aerospace and Electronic Systems | Year: 2015

Noise radars are electromagnetic systems that use random signals for detecting and locating reflecting objects. Besides high performance against external interferences (intentional or not), the stochastic nature of the transmitted waveforms may lead to the suppression of range ambiguity in the detection of targets and low range sidelobes, if systems parameters are properly chosen. This paper addresses a probabilistic analysis to derive mathematical expressions for the signal-to-noise ratios, the peak-to-sidelobe ratios and the signal-to-interference ratios (due to ambiguous targets) throughout a typical receiver processing chain of a pulsed FM noise radar. A receiver that employs matched filtering and pulse integration prior to detection was considered. Pulse compression and integration gains (in signal-to-noise and signal-to-interference, due to ambiguous targets, ratios) are also derived. The analysis provides closed-form expressions relating the precise dependence of sidelobe levels as well as interference levels due to ambiguous targets to the integration time, the transmit signal bandwidth, and the number of integrated pulses. © 2015 IEEE.

Soares F.A.A.,Federal University of Santa Maria | Dalla Corte C.L.,Federal University of Santa Maria | Andrade E.R.,Brazilian Army Technological Center | Marina R.,Autonomous University of Chile | And 2 more authors.
Nutricion Hospitalaria | Year: 2014

The aim of this work was to test the hypothesis that a moderate intake of organic purple grape juice shows a positive radiomodifier effect over early behavioural damage following acute X-irradiation in mice. Anxiety-, locomotion-, and feeding-related responses to 6 Gy total body X-irradiation (TBI) were studied via open field, Rotarod, and feeding/drinking recording. Thirty-two male mice weighing 25-30 g were grouped according grape juice (J) or water (W) ad libitum drinking and either non-irradiated (N) or irradiated (R). 24 h post-TBI the access frequency to the center and corners of the open field was decreased, and the total stay in the corners increased, in RW vs. NW mice. Anxiety-related parameters decreased in RJ vs. RW mice. Rotarod latency times increased 72 h post-TBI in RJ vs RW mice. No overall changes in food and drink intake were observed along the experimental period. On the irradiation day, bout number was increased and bout duration was decreased in RW mice. The changes were reversed by purple grape juice intake. Grape juice intake before and after TBI can overcome several radiation-induced changes in behaviour within 24-72 hours after sub-lethal X-irradiation. This beneficial effect on short-term anxiety and mobility-related activities could probably be included in the list of flavonoid bio-effects. The present findings could be relevant in designing preventive interventions aimed to enhance body defense mechanisms against short-term irradiation damage.

Rita V.A.F.S.,Brazilian Army Technological Center
2015 IEEE Radar Conference - Proceedings | Year: 2015

This work presents a mode S secondary surveillance radar (SSR) architecture that enables signal processing to be done all in software. It avoids a widely implemented architecture approach with a first step of processing with a filter in hardware, normally implemented in FPGA. This proposed architecture replaces the hardware filter with a highly customized filter in software implemented in C language running as an operating system process executed with high priority. The filter in software keeps extracting preambles and payload from noise as hardware counterpart but on a CPU. The further processing steps of the mode S logic was implemented in high level language, simplifying project complexity and maintainability. To validate the architecture, a simulator was implemented with realistic constraints, and was tested with real data in the reception channel. © 2015 IEEE.

Pompeo B.,Brazilian Army Technological Center | Pralon L.,Brazilian Army Technological Center | Pralon M.,Brazilian Army Technological Center | Mendes R.,University of Campinas
European Microwave Week 2013, EuMW 2013 - Conference Proceedings; EuRAD 2013: 10th European Radar Conference | Year: 2013

Current excitation of each active element in a phased array antenna allows for the generation of a specific beam shape. Nevertheless, the transmitter amplifiers can add constraints to the amplitude weights used for feeding the elements. This paper proposes an optimization method for generating a phase-only radiation pattern based on the least squares methods. Furthermore, a comparison is drawn between the proposed method to distinct algorithms referred in the literature. © 2013 EMA.

Ribeiro F.C.,Brazilian Army Technological Center | Marques E.C.,Brazilian Army Technological Center | Paiva N.M.,Brazilian Army Technological Center | Galdino J.F.,Brazilian Army Technological Center
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2015

We compare a compressive sensing-based sparse direct decision-feedback equalization with the conventional structure in a MIL-STD-188-110C military HF receiver. The Stochastic Gradient Pursuit (SGP) adaptive algorithm is considered for the sparse DFE approach, while the conventional DFE runs a variation of the well-known Recursive Least Squares (RLS) algorithm. In addition, a variant of the SGP algorithm (κ-SGP) with reduced support set computations is proposed and analyzed. Results show that the sparsity of the DFE filters can also be exploited in the context of HF communications to derive efficient and better performing receiver implementations. © 2015 IEEE.

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