1,721,011 research outputs found
A Wide Tuning Range MEMS Varactor Based on a Toggle Push-Pull Mechanism
No full textThis paper presents a novel wide tuning range MEMS varactor based on a toggle push – pull mechanism for high RF power applications and improved reliability. The device anchoring utilizes a torsion spring mechanism which virtually allows for a full capacitance tuning range. Improved mechanical stability is also provided by the actively controlled pull-out implementation that is realized without increasing the MEMS manufacturing complexity. As a proof of concept, a toggle MEMS varactor has been modeled, designed and manufactured in shunt configuration on a 50 coplanar transmission line. Analytical and full wave electromechanical models are provided as well as electromagnetic characterization. The device has been manufactured on HR Silicon substrate by using the standard FBK-irst RF MEMS process. Optical profile, DC and RF measurements are presented in the 0-40 GHz frequency band. Excellent RF performance as well as a capacitance tuning ratio of 2.5 has been obtained
A Wide Tuning Range MEMS Varactor Based on a Toggle Push-Pull Mechanism
No full textThis paper presents a novel wide tuning range MEMS varactor based on a toggle push – pull mechanism for high RF power applications and improved reliability. The device anchoring utilizes a torsion spring mechanism which virtually allows for a full capacitance tuning range. Improved mechanical stability is also provided by the actively controlled pull-out implementation that is realized without increasing the MEMS manufacturing complexity. As a proof of concept, a toggle MEMS varactor has been modeled, designed and manufactured in shunt configuration on a 50 coplanar transmission line. Analytical and full wave electromechanical models are provided as well as electromagnetic characterization. The device has been manufactured on HR Silicon substrate by using the standard FBK-irst RF MEMS process. Optical profile, DC and RF measurements are presented in the 0-40 GHz frequency band. Excellent RF performance as well as a capacitance tuning ratio of
2.5 has been obtained
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
An uncooled infrared focal plane array for low-cost applications fabricated with standard CMOS technology
No full textThis paper reports the design, fabrication and assessment of a low-cost uncooled infrared imager that has been conceived as a general purpose system to be used in a wide range of infrared applications. The imager has been fabricated using the AMS 0.8 μm CYE CMOS process together with a compatible front-side bulk micromachining post-process provided by the CMP service of the TIMA laboratory. The adopted fabrication approach does not involve any lithography step, material deposition or particular etch-stop technique after the CMOS process, so that the imager cost is almost equal to the CMOS chip cost. The infrared imager is composed of a focal plane array (FPA) with 16 × 16 thermopile pixels, which are monolithically integrated with the addressing and readout electronics. Each pixel consists of a thermally isolated micromachined membrane suspended by two arms that contain the polysilicon/aluminium thermocouples of the embedded thermopile sensor. The pixel membrane also includes a heating resistor intended to implement a self-test function that allows an electrical test of the FPA without need of specific infrared equipment. Since the voltage levels generated by the thermopile pixels are in the range of a few μV the readout channel consists of a low-noise voltage amplifier with a high variable gain that can be tuned for different operation conditions. The readout circuit makes use of the chopper principle and the correlated double sampling technique to reduce the noise floor and the amplifier offset levels. Optical measurements performed with the fabricated prototypes have shown a pixel responsivity of 15.0 V/W, a noise equivalent power of 1.37 nW and a normalized detectivity of 1.05 × 107 cm Hz1/2 W−1, values that are in line with current state of the art. The readout channel features a maximum gain of 85 dB with a 4.3 kHz bandwidth and an equivalent input noise of 22 nV/Hz1/2. An infrared imager based on the FPA has been build and thermal imaging has been demonstrated
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
An uncooled infrared focal plane array for ultra low-cost applicatons fabricated with standard CMOS technology
No full textThis paper reports the design, fabrication and assessment of a low-cost uncooled infrared imager that has been conceived as a general purpose system to be used in a wide range of infrared applications. The imager has been fabricated using the AMS 0.8 m CYE CMOS process together with a compatible front-side bulk micromachining post-process provided by the CMP service of the TIMA laboratory. The adopted fabrication approach does not involve any lithography step, material deposition or particular etch-stop technique after the CMOS process, so that the imager cost is almost equal to the CMOS chip cost. The infrared imager is composed of a focal plane array (FPA) with 16×16 thermopile pixels, which are monolithically integrated with the addressing and readout electronics. Each pixel consists of a thermally isolated micromachined membrane suspended by two arms that contain the polysilicon/aluminium thermocouples of the embedded thermopile sensor. The pixel membrane also includes a heating resistor intended to implement a self-test function that allows an electrical test of the FPA without need of specific infrared equipment. Since the voltage levels generated by the thermopile pixels are in the range of a few V the readout channel consists of a low-noise voltage amplifier with a high variable gain that can be tuned for different operation conditions. The readout circuit makes use of the chopper principle and the correlated double sampling technique to reduce the noise floor and the amplifier offset levels. Optical measurements performed with the fabricated prototypes have shown a pixel responsivity of 15.0 V/W, a noise equivalent power of 1.37nW and a normalized detectivity
of 1.05×107 cm Hz1/2W−1, values that are in line with current state of the art. The readout channel features a maximum gain of 85 dB with a 4.3 kHz bandwidth and an equivalent input noise of 22 nV/Hz1/2. An infrared imager based on the FPA has been build and thermal imaging has been demonstrated
A CMOS integrated focal plane array for ultra low-cost infrared applications
No full textA prototype of 34x34 pixels vision sensor with on focal
plane image processing is presented. The sensor perform a
wide range of image filtering over a 3x3 pixel kernel,
based on two operations: Absolute Value of the Difference
(AVD) between two signals and Signal Accumulation
(SA). These two functions are implemented at pixel-level
thanks to a high pixel connectivity, allowing both pixel
parallel comp utation with large flexibility in coefficients
assignment. The pixel occupies 35x35 um2 of chip area
with a fill factor of 20%. The total dynamic range of the
sensor is 98 dB. The array was fabricated in 0.35 um
CMOS technology and consumes 6 mW @ 3.3 V
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