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The possibility of vessel motion data use for high resolution satellite SAR image focusing

Dimc F., Cicuendez J. I., Greidanus H., Perkovic M., Gucma M., Silva V., Duczkowski M.

Zeszyty Naukowe / Akademia Morska w Szczecinie

2012

nr 32 (104) z. 2

16-19

Maritime surveillance from space is useful for many applications, such as fisheries control, maritime border control and maritime security. A new generation of satellite-borne Synthetic Aperture Radars is able to provide resolutions of down to 1 meter. In the case of maritime targets, however, their motions lead to blurring in the SAR images, so these high resolutions cannot be attained. Scientific research into how to surmount the existing limits on the use of high-resolution images for maritime surveillance would be of great utility. In this context, high resolution SAR data were collected from ships that have been fitted with motion sensors in order to understand vessel motion impact on detection and recognition capability.

Thermal assisted switching magnetic tunnel junctions as FPGA memory elements

Silva V., Fernandes J. R., Oliveira L. B., Neto H. C., Ferreira R., Freitas S., Freitas P. P.

International Journal of Microelectronics and Computer Science

2010

Vol. 1, nr 1

31-36

This paper presents our research and development work on new circuits and topologies based on Magnetic RAM for use as configuration memory elements of reconfigurable arrays. MRAM provides non volatility with cell areas and with access speeds comparable to those of SRAM and with lower process complexity than FLASH memories. The new memory cells take advantage of the Thermal Assisted Switching (TAS) writing technique to solve the drawbacks of the more common Field Induced Magnetic Switching writing technique. The CMOS circuit structures to implement the main components for reading and writing the MTJ cells have been developed, characterized and evaluated. A scaled down prototype of a coarse grain reconfigurable array that employs the TAS-MRAM elements as configuration memory has been designed and electrically simulated pre- and post- layout. The results obtained for all the circuit elements, namely the storage cells and the current generators, indicate that the new configuration memory cells can provide a very promising technological solution for run-time reconfigurable hardware devices. The prototype has been manufactured using a standard process 0.35μm 4-Metal CMOS process technology and should be under test in the foreseeable future.

Tribological behaviour of SiC particulate reinforced aluminium alloy composites in unlubricated sliding against cast iron

Gomes J. R., Miranda A. S., Rocha L. A., Crnkovic S. J., Silva V., Silva R. F.

International Journal of Applied Mechanics and Engineering

2002

Vol. 7, no 3

791-802

Functionally graded metal matrix composites (FGMMCs) are novel materials attractive for aircraft and automotive tribological components. A superior combination of surface and bulk mechanical properties may be pointed as one of the main advantages of this new material concept. In particular, through an adequate control of the ceramic particles distribution from the surface down to the core of the component, the wear resistance may be improved at the surface while global toughness is preserved. In this work, the tribological behaviour of a Al-9%Si alloy reinforced with SiC particles processed by gravity and centrifugal casting is compared. Wear tests were performed using the pin-on-disc configuration, the composite being the disc while pins were built in cast iron. Sliding speed (0.5-1.5ms-1) and disc temperature (22-300oC) were the main variables considered in the tests. Results suggest that formation of adherent iron-rich tribolayers in tests carried-out at room temperature is the main mechanism leading to an improvement of the wear resistance. For v=0.5ms-1 , this effect is enhanced in the material obtained by centrifugal casting in which the surface area fraction of particles is higher. Temperature (externally applied or due to frictional heating) degrades the tribological performance of the reinforced materials, promoting transfer of aluminium from the disc to the cast iron counterface.