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Ferri, Matteo,Mancarella, Fulvio,Seshia, Ashwin,Ransley, James,Soga, Kenichi,Zalesky, Jan,Roncaglia, Alberto Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.3
We report on the development of a new technology for the fabrication of Micro-Electro-Mechanical-System (MEMS) strain sensors to realize a novel type of crackmeter for health monitoring of ageing civil infrastructures. The fabrication of micromachined silicon MEMS sensors based on a Silicon On Insulator (SOI) technology, designed according to a Double Ended Tuning Fork (DETF) geometry is presented, using a novel process which includes a gap narrowing procedure suitable to fabricate sensors with low motional resistance. In order to employ these sensors for crack monitoring, techniques suited for bonding the MEMS sensors on a steel surface ensuring good strain transfer from steel to silicon and a packaging technique for the bonded sensors are proposed, conceived for realizing a low-power crackmeter for ageing infrastructure monitoring. Moreover, the design of a possible crackmeter geometry suited for detection of crack contraction and expansion with a resolution of $10{\mu}m$ and very low power consumption requirements (potentially suitable for wireless operation) is presented. In these sensors, the small crackmeter range for the first field use is related to long-term observation on existing cracks in underground tunnel test sections.
Nonlinear programming approach for a class of inverse problems in elastoplasticity
Ferris, M.C.,Tin-Loi, F. Techno-Press 1998 Structural Engineering and Mechanics, An Int'l Jou Vol.6 No.8
This paper deals with a special class of inverse problems in discrete structural plasticity involving the identification of elastic limits and hardening moduli on the basis of information on displacements. The governing equations lead naturally to a special and challenging optimization problem known as a Mathematical Program with Equilibrium Constraints (MPEC), a key feature of which is the orthogonality of two sign-constrained vectors or so-called "complementarity" condition. We investigate numerically the application of two simple algorithms, both based on the use of the general purpose nonlinear programming code CONOPT accessed via the GAMS modeling language, for solving the suitably reformulated problem. Application is illustrated by means of two numerical examples.
Giuseppe Ferri,Vincenzo Stornelli,Angelo Celeste 한국전자통신연구원 2007 ETRI Journal Vol.29 No.6
In this paper, we present an integrated rail-to-rail fully differential operational transconductance amplifier (OTA) working at low-supply voltages (1.5 V) with reduced power consumption and showing high DC gain. An embedded adaptive biasing circuit makes it possible to obtain low stand-by power dissipation (lower than 0.17 mW in the rail-to-rail version), while the high DC gain (over 78 dB) is ensured by positive feedback. The circuit, fabricated in a standard CMOS integrated technology (AMS 0.35 μm), presents a 37 V/μs slew-rate for a capacitive load of 15 pF. Experimental results and high values of two quality factors, or figures of merit, show the validity of the proposed OTA, when compared with other OTA configurations.
Local Electrical Characterization of PVDF Textile Filament
Anthony Ferri,François Rault,Antonio Da Costa,Cédric Cochrane,Matthieu Boudriaux,Guillaume Lemort,Christine Campagne,Eric Devaux,Christian Courtois,Rachel Desfeux 한국섬유공학회 2019 Fibers and polymers Vol.20 No.7
The piezoelectric behavior of poly(vinylidene fluoride), PVDF, has been known for several decades and is clearlyrelated to its crystalline phases. Many works made on films or fibers have focused on the characterization of the phasetransitions during various PVDF processing and on its electromechanical activity by combining several techniques. Piezoforcemicroscopy (PFM) is an interesting tool to underline the crystalline forms and piezoelectricity efficiency of PVDF atthe local scale. However, this technique is little used on samples in the form of fibers and in this case, it is most oftennanofibers. In this work, two conventional PVDF textile filaments, with different weak draw ratio, are produced and analyzedby FTIR, XRD, and PFM. We demonstrate that the PFM analysis can be relevant for specimens presenting low signals duringother characterizations. Therefore, the local piezo-/ferroelectricity into the fiber is highlighted underlining the existence of thepolar phases of PVDF. Then, the effective piezoelectric coefficient d33 of PVDF fiber drawn with a ratio of 1.5 is estimated at12 pm/V.
Matteo Ferri,Fulvio Mancarella,Ashwin Seshia,James Ransley,Kenichi Soga,Jan Zalesky,Alberto Roncaglia 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.3
We report on the development of a new technology for the fabrication of Micro-Electro-Mechanical-System (MEMS) strain sensors to realize a novel type of crackmeter for health monitoring of ageing civil infrastructures. The fabrication of micromachined silicon MEMS sensors based on a Silicon On Insulator (SOI) technology, designed according to a Double Ended Tuning Fork (DETF) geometry is presented, using a novel process which includes a gap narrowing procedure suitable to fabricate sensors with low motional resistance. In order to employ these sensors for crack monitoring, techniques suited for bonding the MEMS sensors on a steel surface ensuring good strain transfer from steel to silicon and a packaging technique for the bonded sensors are proposed, conceived for realizing a low-power crackmeter for ageing infrastructure monitoring. Moreover, the design of a possible crackmeter geometry suited for detection of crack contraction and expansion with a resolution of 10 and very low power consumption requirements (potentially suitable for wireless operation) is presented. In these sensors, the small crackmeter range for the first field use is related to long-term observation on existing cracks in underground tunnel test sections.