1,720,984 research outputs found
Spread-Spectrum Modulated Multi-Channel Biosignal Acquisition Using a Shared Analog CMOS Front-End
Get PDFThe key challenges in designing a multi-channel biosignal acquisition system for an ambulatory or invasive medical application with a high channel count are reducing the power consumption, area consumption and the outgoing wire count. This article proposes a spread-spectrum modulated biosignal acquisition system using a shared amplifier and an analog-to-digital converter (ADC). We propose a design method to optimize a recording system for a given application based on the required SNR performance, number of inputs, and area. The proposed method is tested and validated on real pre-recorded atrial electrograms and achieves an average percentage root-mean-square difference (PRD) performance of 2.65% and 3.02% for sinus rhythm (SR) and atrial fibrillation (AF), respectively by using pseudo-random binary-sequence (PRBS) codes with a code-length of 511, for 16 inputs. We implement a 4-input spread-spectrum analog front-end in a CMOS process to demonstrate the proposed approach. The analog front-end consists of a shared amplifier, a 2nd order ADC sampled at , used for digitization, and an on-chip 7-bit PRBS generator. It achieves a number-of-inputs to outgoing-wire ratio of 4:1 while consuming /input including biasing from a power supply and in area
A wide bandwidth, on-line impedance measurement method for power systems, based on PLC techniques
No full textOn-line impedance measurement is a useful tool to monitor the state, health and characteristics of electrical networks in power systems. This paper proposes a method for on-line, wide-bandwidth, impedance analysis of devices used in power networks. This method uses a signal generator to inject other than mains frequency signals on-line and then measuring current and voltages to determine the impedance at the injected frequencies. Two measurement circuits based on different types of current and voltage measurement methods are discussed. Their experimental results of impedance measurement are shown. This paper also suggested some possible applications of this on-line impedance analysis method in condition monitoring of power distribution transformers and electrical machines
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Analysis and Design of Power Supply Circuits for RF Oscillators
No full textThis article presents guidelines for designing the power supply blocks of RF oscillators. To preserve their spectral purity, the requirements on the noise and ripple of the supply voltage are firstly evaluated based on the oscillator supply pushing factor and the oscillator Figure-of-Merit (FOM). Those specifications are then employed to design and estimate the power efficiency of an analog low-dropout regulator (LDO) and a switched-capacitor DC-DC converter. As a proof of concept, a 2:1 or 3:2 switched-capacitor DC-DC converter is implemented and directly connected to our previously published 4.9-5.5 GHz LC oscillator. The converter provides a 1V supply voltage with a noise ≤0.9nV/√Hz at 1MHz and does not affect the inherent phase noise of the oscillator. The ripple amplitude of the converter is 30mV while its effect is suppressed by the spur reduction block embedded in the oscillator.Bio-ElectronicsElectronic InstrumentationElectronic
Variations on the Author
Get PDF“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
A UWB CMOS 0.13μm low-noise amplifier with dual loop negative feedback
No full textA Low-Noise Amplifier for ultra wide band (UWB) applications is presented. The use of a dual-loop negative feedback topology is advantageous, since it allows to achieve both impedance matching and a very low noise figure, and saves a lot of chip area as no bulky inductors are needed. A nullor and a resistive feedback network are employed, and the values of the feedback elements involved are defined in order to fulfill the noise-figure, input impedance and power-gain requirements for an UWB receiver. To ensure circuit stability, frequency compensation is done by means of a phantom zero and the addition of a transistor connected between input and output, thus realizing a multipath structure. The design targets UMC 0.13μm CMOS IC technology and operation from a 1.2-volt supply. From circuit simulations, the power gain of the LNA amounts to 17dB, and the bandwidth spans up to 12GHz. S11 is below -10dB up to 10GHz and the noise figure is below 3dB up to 8GHz, and below 4dB@10GHz. The power consumption equals 14mA. Compared to competitive solutions, using resonating load stages or LC ladder networks, this chip will be much smaller and cheaper; it will use standard CMOS technology, and achieve very low noise, high gain and wide band matching at reasonable power consumption. ©2008 IEEE
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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