1,721,034 research outputs found
Automatic Differentiation for Inverse Problems in X-ray Imaging and Microscopy
Full text linkComputational techniques allow breaking the limits of traditional imaging methods, such as time restrictions, resolution, and optics flaws. While simple computational methods can be enough for highly controlled microscope setups or just for previews, an increased level of complexity is instead required for advanced setups, acquisition modalities or where uncertainty is high; the need for complex computational methods clashes with rapid design and execution. In all these cases, Automatic Differentiation, one of the subtopics of Artificial Intelligence, may offer a functional solution, but only if a GPU implementation is available. In this paper, we show how a framework built to solve just one optimisation problem can be employed for many different X-ray imaging inverse problems
Design of a 17.3-21.2 GHz SATCOM Upconverter Based on COTS with Low Spurious Emission
No full textThis paper presents the design of an upconverter system based on Commercial Off-The-Shelf (COTS) components for the 17.3-21.2 GHz space-to-Earth Fixed Satellite Services (FSS) frequency band, with a variable Intermediate Frequency (IF) up to 4 GHz. The proposed system combines Upper SideBand (USB) and Lower Side-Band (LSB) frequency conversion modes and Local Oscillator (LO) leakage nulling techniques to enhance Spurious-Free Dynamic Range (SFDR). LO leakage nulling was used to show that it is possible to improve a minimum 31 dBc SFDR in the FSS bandwidth to 48 dBc. The upconverter was connected to a 10 W power amplifier, limited in the 17.3-20.2 GHz band, and its performance was compared with the International Telecommunication Union (ITU) recommendation on spurious emissions. The system is compliant for all the RF bandwidth within IF band 2.5-3.5 GHz and in the RF sub-band 17.8-20.2 GHz for IF band 3.5-4.0 GHz. The proposed system was then evaluated at sample RF and IF frequencies in terms of Error Vector Magnitude (EVM)
Minimum hardware serial PID regulator for high efficiency, low power digital DC-DC converters
No full textThis paper focuses on the minimum hardware implementation of a digital compensator for digitally controlled dc-dc converters. A novel serial PID architecture is presented that, together with the adopted representation of controller parameters, minimizes the area requirements while allowing the representation of a wide range of parameter values. Large multipliers and wide look-up tables are thus avoided, making this architecture well suited to applications where small size and low power consumption are required. Analysis of the serial PID compensator and simulation results are presented for a multi-mode buck converter for automotive applications, highlighting the advantages of the proposed architecture. ©2010 IEEE
Whole field optical profilometry: application of nonlinear processing algorithms to the enhancement of low-contrast images
No full textDESIGN AND IMPLEMENTATION OF AN FPGA-BASED DIGITAL PROCESSOR FOR BPM APPLICATIONS
No full textDigital processing systems have been proven to often outperform ana-
log elaboration. Indeed, thanks to high-density DSPs and FPGAs, op-
erations in digital domain give results that are impossible to achieve in
other ways. On the other side, dealing with this great performance and
fl exibility is not always straightforward: the processing chain needs to
be accurately planned to reach the desired goals, avoiding erratic be-
haviours in the digital domain. In this paper, we focus on the design
and implementation of an FPGA-based digital processor that will be
used in the electron beam position monitors of Elettra 2.0. After digi-
tizing the 500 MHz beam signals from the pickups, the system executes
a digital down conversion, followed by several fi ltering and demodulat-
ing stages, in order to have a selectable data rate that is suitable for both
diagnostics and feedback. The position calculation is also performed in
FPGA as well, with the well-known difference-over-sum algorithm. Ac-
cording to results provided by a fi xed-point simulation, the overall sys-
tem has been implemented in an Intel Arria 10 FPGA, demonstrating
the correct design functionality that meets the specifi ed requirements
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
Un sistema di Supporto Decisionale per la prevenzione degli squilibri glicemici da sforzo nel paziente diabetico insulino-dipendente
No full textVariations 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
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