Vittorio Ferrari - Academia.edu (original) (raw)
Uploads
Papers by Vittorio Ferrari
A microfluidic sensor for detection of cells flowing in a microchannel is presented. The sensor c... more A microfluidic sensor for detection of cells flowing in a microchannel is presented. The sensor consists of a PDMS (PolyDiMethylSiloxane) layer with two planar microreservoirs connected by a microchannel. The bottom sides of the microreservoirs are faced to two sensing electrodes realized on a PCB (Printed Circuit Board). A noncontact measurement is ensured by an insulator layer between the electrodes and the fluid.
Ieee Transactions on Instrumentation and Measurement, 2006
This paper proposes a new full digital approach to estimate biaxial position with a pyroelectric ... more This paper proposes a new full digital approach to estimate biaxial position with a pyroelectric sensor array. The previously developed analog interface shows its limits in the calibration procedure, requiring several trimming adjustments. A DSP-based hardware has been developed to experimentally evaluate three digital methods: radial basis function (RBF) neural network, best fitted plane (BFP), and look-up table (LUT) in the least mean square (LMS) error sense. Experimental results show that no dramatic improvements are obtained by the RBF, despite the long training required and the external PC support for weight calculation. The BFP reaches performances comparable to the analog processing system using only nine calibration points, but the best tradeoff has been found with the LUT technique. Actually, with a 64-point calibration set, LUT gives a root mean square error (RMSE) of 0.5% with respect to full scale (FS), offering a valid in-circuit compensation of array structural defects.
We present a family of scale-invariant local shape features formed by chains of k connected rough... more We present a family of scale-invariant local shape features formed by chains of k connected roughly straight contour segments (kAS), and their use for object class detection. kAS are able to cleanly encode pure fragments of an object boundary without including nearby clutter. Moreover, they offer an attractive compromise between information content and repeatability and encompass a wide variety of local shape structures. We also define a translation and scale invariant descriptor encoding the geometric configuration of the segments within a kAS, making kAS easy to reuse in other frameworks, for example, as a replacement or addition to interest points (IPs). Software for detecting and describing kAS is released at http://lear.inrialpes.fr/software. We demonstrate the high performance of kAS within a simple but powerful sliding-window object detection scheme. Through extensive evaluations, involving eight diverse object classes and more than 1,400 images, we 1) study the evolution of performance as the degree of feature complexity k varies and determine the best degree, 2) show that kAS substantially outperform IPs for detecting shape-based classes, and 3) compare our object detector to the recent state-of-the-art system by Dalal and Triggs [4].
Sensors and Actuators a Physical, Sep 1, 2010
A sensor system for the study of oil–water flow in pipes is proposed. The purpose is to estimate ... more A sensor system for the study of oil–water flow in pipes is proposed. The purpose is to estimate the area fraction occupied by each fluid in a given section of the pipe, taking advantage of the difference in dielectric permittivity between the fluids. The estimation is done by capacitance measurements between electrodes flush-mounted on the external surface of a nonconductive
... Page 2. Page 3. Page 4. Page 5. Applied Structural and Mechanical Vibrations This One EAB5-E8... more ... Page 2. Page 3. Page 4. Page 5. Applied Structural and Mechanical Vibrations This One EAB5-E8C-FK79 Page 6. Page 7. Applied Structural ...
Sensors and Actuators B Chemical
ABSTRACT
A contactless electromagnetic principle for the excitation of mechanical vibrations in resonant s... more A contactless electromagnetic principle for the excitation of mechanical vibrations in resonant structures has been investigated. The principle relies on no specific magnetic property of the resonator except electrical conductivity and can be adopted for employing the structures as resonant sensors for measurements either in environments not compliant with the requirements of active electronics or in limited accessibility environments. An external coil is employed as an excitation source which inductively couples to the conductive surface of the resonator or to a secondary coil connected to conductive paths on the resonant structure. Exploiting the interaction of the induced currents with AC or DC magnetic fields, Lorentz forces are generated which can set the resonator into vibration. Preliminary tests on miniaturized resonators have been performed, namely cantilevers and clamped-clamped beams. The principle has been subsequently implemented in the design of MEMS resonators. Experimental verifications have shown the possibility of contactless exciting microresonators over short-range distances.
Sensors and Microsystems, 2004
ABSTRACT This work illustrates comparative experiments on 10-MHz AT-cut thickness-shear mode quar... more ABSTRACT This work illustrates comparative experiments on 10-MHz AT-cut thickness-shear mode quartz crystal microbalance (QCM) sensors and 7-MHz resonant piezo-layer (RPL) sensors made by lead zirconate titanate (PZT) thick films screen-printed on alumina substrate. The sensors were sensitized with cavitand coatings (Qx-Cav and Me-Cav) and exposed to different organic vapors to evaluate their different performances.
IEEE Sensors, 2005., 2005
A configuration and method for contactless readout of the resonance response of a thickness-shear... more A configuration and method for contactless readout of the resonance response of a thickness-shear mode quartz resonator sensor is presented. The configuration uses a crystal with a large common electrode on the front face, and one, or more, small electrodes on the back face, leading to localized sensing regions. Each back electrode is capacitively coupled to a separated tip electrode.
Given a corpus of news items consisting of images accompanied by text captions, we want to find o... more Given a corpus of news items consisting of images accompanied by text captions, we want to find out "who's doing what", i.e. associate names an d action verbs in the captions to the face and body pose of the persons in the images. We present a joint model for simultaneously solving the image-caption correspondences and learning visual appearance models for
2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2015
ABSTRACT We propose an unsupervised approach for discovering characteristic motion patterns in vi... more ABSTRACT We propose an unsupervised approach for discovering characteristic motion patterns in videos of highly articulated objects performing natural, unscripted behaviors, such as tigers in the wild. We discover consistent patterns in a bottom-up manner by analyzing the relative displacements of large numbers of ordered trajectory pairs through time, such that each trajectory is attached to a different moving part on the object. The pairs of trajectories descriptor relies entirely on motion and is more discriminative than state-of-the-art features that employ single trajectories. Our method generates temporal video intervals, each automatically trimmed to one instance of the discovered behavior, and clusters them by type (e.g., running, turning head, drinking water). We present experiments on two datasets: dogs from the YouTube objects and a new dataset of National Geographic tiger videos. Results confirm that our proposed descriptor outperforms existing appearance- and trajectory-based descriptors (e.g., HOG and IDTF) on both datasets and enables us to segment unconstrained animal video into intervals containing single behaviors.
Procedia Engineering, 2014
The conversion of mechanical energy from environmental vibrations into electrical energy is a key... more The conversion of mechanical energy from environmental vibrations into electrical energy is a key point for powering sensor nodes, toward the development of autonomous sensor systems. Piezoelectric energy converters realized in a cantilever configuration are the most studied for this purpose. In order to improve the performances of the converter, the geometry has to be properly designed. In this context FEM simulations have been used in order to optimize the piezoelectric layer thickness. A parametrized geometry was created by means of moving mesh application mode. The electrical energy generated by the converter under an applied acceleration was computed, finding the optimal thickness for the piezoelectric layer. Different geometries were considered verifying that they do not affect the optimal thickness.
In this paper a piezoelectric ink with curing temperature as low as 150°C is presented. It is int... more In this paper a piezoelectric ink with curing temperature as low as 150°C is presented. It is intended to be used in MEMS, sensors, actuators and power harvesting field. Ink composition and fabrication steps are described. Electrical characterization of a ink film sample realized with screen printing technology is reported, showing a dielectric constant εr 10 = 100 ± 10%. The ferroelectric hysteresis loop of the piezoelectric ink has been measured by means of a custom PC-based measurement system. A remanent polarization of 0.8 μC/cm2 was measured with a maximum applied electric field of about 13 MV/m. In addition, the possibility of depositing the ink with a drop-on-demand technology was demonstrated, by using a commercial piezoelectric microdispensing device with a 80-μm diameter orifice. Dissolving the PZT ink in ethylene glycol diacetate, wt ratio 1:3, single drops with a diameter of 175 μm have been deposited.
This work proposes a portable system for the measurement of ECG with a one-lead configuration for... more This work proposes a portable system for the measurement of ECG with a one-lead configuration for long term recording. The collected data are stored on high-density SD card for off-line examination. The present implementation focuses on low-power electronics to increase the battery lifetime, achieving about 16-h duration with two 158-mAh capacity batteries. The system has proved to be able to detect heart rate anomalies on test subjects.
Piezoelectric Transducers and Applications, 2008
ABSTRACT
2010 IEEE Sensors, 2010
A thermal flow sensor with smart electronic interface is presented. The sensor is based on four g... more A thermal flow sensor with smart electronic interface is presented. The sensor is based on four germanium thermistors embedded in a thin membrane and connected to form a Wheatstone bridge. Both the bridge unbalance voltage and the voltage at the bridge supply terminals under constant current excitation are functions of the flow offering high initial sensitivity and wide measurement range,
A microfluidic sensor for detection of cells flowing in a microchannel is presented. The sensor c... more A microfluidic sensor for detection of cells flowing in a microchannel is presented. The sensor consists of a PDMS (PolyDiMethylSiloxane) layer with two planar microreservoirs connected by a microchannel. The bottom sides of the microreservoirs are faced to two sensing electrodes realized on a PCB (Printed Circuit Board). A noncontact measurement is ensured by an insulator layer between the electrodes and the fluid.
Ieee Transactions on Instrumentation and Measurement, 2006
This paper proposes a new full digital approach to estimate biaxial position with a pyroelectric ... more This paper proposes a new full digital approach to estimate biaxial position with a pyroelectric sensor array. The previously developed analog interface shows its limits in the calibration procedure, requiring several trimming adjustments. A DSP-based hardware has been developed to experimentally evaluate three digital methods: radial basis function (RBF) neural network, best fitted plane (BFP), and look-up table (LUT) in the least mean square (LMS) error sense. Experimental results show that no dramatic improvements are obtained by the RBF, despite the long training required and the external PC support for weight calculation. The BFP reaches performances comparable to the analog processing system using only nine calibration points, but the best tradeoff has been found with the LUT technique. Actually, with a 64-point calibration set, LUT gives a root mean square error (RMSE) of 0.5% with respect to full scale (FS), offering a valid in-circuit compensation of array structural defects.
We present a family of scale-invariant local shape features formed by chains of k connected rough... more We present a family of scale-invariant local shape features formed by chains of k connected roughly straight contour segments (kAS), and their use for object class detection. kAS are able to cleanly encode pure fragments of an object boundary without including nearby clutter. Moreover, they offer an attractive compromise between information content and repeatability and encompass a wide variety of local shape structures. We also define a translation and scale invariant descriptor encoding the geometric configuration of the segments within a kAS, making kAS easy to reuse in other frameworks, for example, as a replacement or addition to interest points (IPs). Software for detecting and describing kAS is released at http://lear.inrialpes.fr/software. We demonstrate the high performance of kAS within a simple but powerful sliding-window object detection scheme. Through extensive evaluations, involving eight diverse object classes and more than 1,400 images, we 1) study the evolution of performance as the degree of feature complexity k varies and determine the best degree, 2) show that kAS substantially outperform IPs for detecting shape-based classes, and 3) compare our object detector to the recent state-of-the-art system by Dalal and Triggs [4].
Sensors and Actuators a Physical, Sep 1, 2010
A sensor system for the study of oil–water flow in pipes is proposed. The purpose is to estimate ... more A sensor system for the study of oil–water flow in pipes is proposed. The purpose is to estimate the area fraction occupied by each fluid in a given section of the pipe, taking advantage of the difference in dielectric permittivity between the fluids. The estimation is done by capacitance measurements between electrodes flush-mounted on the external surface of a nonconductive
... Page 2. Page 3. Page 4. Page 5. Applied Structural and Mechanical Vibrations This One EAB5-E8... more ... Page 2. Page 3. Page 4. Page 5. Applied Structural and Mechanical Vibrations This One EAB5-E8C-FK79 Page 6. Page 7. Applied Structural ...
Sensors and Actuators B Chemical
ABSTRACT
A contactless electromagnetic principle for the excitation of mechanical vibrations in resonant s... more A contactless electromagnetic principle for the excitation of mechanical vibrations in resonant structures has been investigated. The principle relies on no specific magnetic property of the resonator except electrical conductivity and can be adopted for employing the structures as resonant sensors for measurements either in environments not compliant with the requirements of active electronics or in limited accessibility environments. An external coil is employed as an excitation source which inductively couples to the conductive surface of the resonator or to a secondary coil connected to conductive paths on the resonant structure. Exploiting the interaction of the induced currents with AC or DC magnetic fields, Lorentz forces are generated which can set the resonator into vibration. Preliminary tests on miniaturized resonators have been performed, namely cantilevers and clamped-clamped beams. The principle has been subsequently implemented in the design of MEMS resonators. Experimental verifications have shown the possibility of contactless exciting microresonators over short-range distances.
Sensors and Microsystems, 2004
ABSTRACT This work illustrates comparative experiments on 10-MHz AT-cut thickness-shear mode quar... more ABSTRACT This work illustrates comparative experiments on 10-MHz AT-cut thickness-shear mode quartz crystal microbalance (QCM) sensors and 7-MHz resonant piezo-layer (RPL) sensors made by lead zirconate titanate (PZT) thick films screen-printed on alumina substrate. The sensors were sensitized with cavitand coatings (Qx-Cav and Me-Cav) and exposed to different organic vapors to evaluate their different performances.
IEEE Sensors, 2005., 2005
A configuration and method for contactless readout of the resonance response of a thickness-shear... more A configuration and method for contactless readout of the resonance response of a thickness-shear mode quartz resonator sensor is presented. The configuration uses a crystal with a large common electrode on the front face, and one, or more, small electrodes on the back face, leading to localized sensing regions. Each back electrode is capacitively coupled to a separated tip electrode.
Given a corpus of news items consisting of images accompanied by text captions, we want to find o... more Given a corpus of news items consisting of images accompanied by text captions, we want to find out "who's doing what", i.e. associate names an d action verbs in the captions to the face and body pose of the persons in the images. We present a joint model for simultaneously solving the image-caption correspondences and learning visual appearance models for
2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2015
ABSTRACT We propose an unsupervised approach for discovering characteristic motion patterns in vi... more ABSTRACT We propose an unsupervised approach for discovering characteristic motion patterns in videos of highly articulated objects performing natural, unscripted behaviors, such as tigers in the wild. We discover consistent patterns in a bottom-up manner by analyzing the relative displacements of large numbers of ordered trajectory pairs through time, such that each trajectory is attached to a different moving part on the object. The pairs of trajectories descriptor relies entirely on motion and is more discriminative than state-of-the-art features that employ single trajectories. Our method generates temporal video intervals, each automatically trimmed to one instance of the discovered behavior, and clusters them by type (e.g., running, turning head, drinking water). We present experiments on two datasets: dogs from the YouTube objects and a new dataset of National Geographic tiger videos. Results confirm that our proposed descriptor outperforms existing appearance- and trajectory-based descriptors (e.g., HOG and IDTF) on both datasets and enables us to segment unconstrained animal video into intervals containing single behaviors.
Procedia Engineering, 2014
The conversion of mechanical energy from environmental vibrations into electrical energy is a key... more The conversion of mechanical energy from environmental vibrations into electrical energy is a key point for powering sensor nodes, toward the development of autonomous sensor systems. Piezoelectric energy converters realized in a cantilever configuration are the most studied for this purpose. In order to improve the performances of the converter, the geometry has to be properly designed. In this context FEM simulations have been used in order to optimize the piezoelectric layer thickness. A parametrized geometry was created by means of moving mesh application mode. The electrical energy generated by the converter under an applied acceleration was computed, finding the optimal thickness for the piezoelectric layer. Different geometries were considered verifying that they do not affect the optimal thickness.
In this paper a piezoelectric ink with curing temperature as low as 150°C is presented. It is int... more In this paper a piezoelectric ink with curing temperature as low as 150°C is presented. It is intended to be used in MEMS, sensors, actuators and power harvesting field. Ink composition and fabrication steps are described. Electrical characterization of a ink film sample realized with screen printing technology is reported, showing a dielectric constant εr 10 = 100 ± 10%. The ferroelectric hysteresis loop of the piezoelectric ink has been measured by means of a custom PC-based measurement system. A remanent polarization of 0.8 μC/cm2 was measured with a maximum applied electric field of about 13 MV/m. In addition, the possibility of depositing the ink with a drop-on-demand technology was demonstrated, by using a commercial piezoelectric microdispensing device with a 80-μm diameter orifice. Dissolving the PZT ink in ethylene glycol diacetate, wt ratio 1:3, single drops with a diameter of 175 μm have been deposited.
This work proposes a portable system for the measurement of ECG with a one-lead configuration for... more This work proposes a portable system for the measurement of ECG with a one-lead configuration for long term recording. The collected data are stored on high-density SD card for off-line examination. The present implementation focuses on low-power electronics to increase the battery lifetime, achieving about 16-h duration with two 158-mAh capacity batteries. The system has proved to be able to detect heart rate anomalies on test subjects.
Piezoelectric Transducers and Applications, 2008
ABSTRACT
2010 IEEE Sensors, 2010
A thermal flow sensor with smart electronic interface is presented. The sensor is based on four g... more A thermal flow sensor with smart electronic interface is presented. The sensor is based on four germanium thermistors embedded in a thin membrane and connected to form a Wheatstone bridge. Both the bridge unbalance voltage and the voltage at the bridge supply terminals under constant current excitation are functions of the flow offering high initial sensitivity and wide measurement range,