2005
Autores
Romero, R; Frazao, O; Pereira, DA; Salgado, HM; Araujo, FM; Ferreira, LA;
Publicação
APPLIED OPTICS
Abstract
An intensity-referenced temperature-independent curvature-measurement technique that uses a smart composite that comprises two chirped fiber Bragg gratings is demonstrated. The two gratings are embedded on opposite sides of the composite laminate and act simultaneously as curvature sensors and as wavelength discriminators, enabling a temperature-independent intensity-based scheme to measure radius of curvature. Also, the system's performance is independent of arbitrary power losses that are induced in the lead fibers to the sensing head. It is demonstrated that the measurement range depends on the relative positions of the chirped fiber Bragg gratings and on their spectral bandwidths. By using two chirped fiber Bragg gratings with bandwidths W-1 = 2.8 nm and W-2 = 3.7 nm and with central wavelengths at lambda(01) = 1560.3 nm and lambda(02) - 1563.7 nm, we obtained a resolution of 1.6 mm/(1)Hz for the measurement of the radius of curvature (similar to R = 350 mm) over the measurement range 190 mm < R < infinity. (c) 2005 Optical Society of America.
2005
Autores
Rego, G; Falate, R; Kalinowski, HJ; Fabris, JL; Marques, PVS; Salgado, HM; Santos, JL;
Publicação
17th International Conference on Optical Fibre Sensors, Pts 1 and 2
Abstract
A compact sensor able to discriminate between temperature and strain related effects was implemented. The proposed sensing head comprises a single long-period grating with two sections written consecutively in the SMF-28 fiber, by the electric arc discharge technique, using different fabrication parameters. The sensor performance is based on the distinct temperature and strain sensitivity values presented by two neighbor resonances belonging to each grating section. The temperature and strain resolutions are +/- 0.1 degrees C and +/- 40 mu epsilon, respectively.
2005
Autores
Ferreira, JC; Silva, MM;
Publicação
19th International Parallel and Distributed Processing Symposium (IPDPS 2005), CD-ROM / Abstracts Proceedings, 4-8 April 2005, Denver, CO, USA
Abstract
We report on work in progress that aims to provide a run-time management kernel for applications running on FPGAs with embedded CPUs. We describe the global concept, the organization of the hardware environment for the reconfigurable modules and the reconfiguration strategy supported by the run-time management kernel. Practical issues concerning the implementation of the system on a Virtex-II Pro-based board are also addressed.
2005
Autores
Silva, ML; Ferreira, JC;
Publicação
DSD 2005: 8th Euromicro Conference on Digital System Design, Proceedings
Abstract
The paper describes the organization and use of a pipeline that is tightly-coupled to the CPU inside a platform FPGA with support for dynamic partial reconfiguration. It describes the overall hardware system organization and the pipeline structure, and presents the associated development environment and run-time support system, including the support for dynamically changing pipeline implementations and altering the operations of a pipeline stage.
2005
Autores
Ferreira, A; Sinha, D;
Publicação
2005 WORKSHOP ON APPLICATIONS OF SIGNAL PROCESSING TO AUDIO AND ACOUSTICS (WASPAA)
Abstract
This paper presents new results improving by a factor of 10 the accuracy of an Odd-DFT based frequency estimation algorithm. These results are shown to be robust to the influence of additive noise and compare favorably to other non-iterative frequency domain estimation algorithms. A perspective is given oil possible application areas, namely those involving real-time constraints.
2005
Autores
Leite, A; Ferreira, AJS;
Publicação
Audio Engineering Society - 118th Convention Spring Preprints 2005
Abstract
This paper presents several improvements that have been introduced to the design and operation of an adaptive 20-band room equalizer. The equalizer is implemented on a TMS320C6711 DSP platform and performs fast FIR filtering in the frequency domain. In order to reach fast adaptation to time-varying acoustic conditions, several adaptation rules operating in the frequency domain have been evaluated and the impact of a frequency-varying stepsize parameter on the convergence rate has been studied. These results will be presented along with ideas and plans for future developments.
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