1,720,970 research outputs found
A Quadrature RC Oscillator With Noise Reduction by Voltage Swing Control
No full textThis paper presents a low power and low noise quadrature RC oscillator based on a frequency locked loop. Voltage swing control of each of the two sub-oscillators reduces the effect of 1/f noise on the accumulated jitter. In addition, the use of quadrature phases greatly relieves timing constraints of sampling operations and helps the reduction of power consumption. With a discrete-time modeling of the quadrature oscillator, noise analysis is also provided for quantitative estimation of the circuit-driven effects on the phase noise. The proposed oscillator is fabricated using 180-nm CMOS process in an active area of 0.058mm(2). The measurement shows a period jitter of 0.047% and a standard deviation of 0.94% in untrimmed frequency (444.9kHz) in a wafer. The oscillator achieves a figure-of-merit of 155 dBc/Hz at 100 Hz offset frequency.11Nsciescopu
An estimation method of an electrical equivalent circuit considering acoustic radiation efficiency for a multiple resonant transducer
No full textThe electrical equivalent model of an underwater acoustic transducer must be exactly defined in the operating frequency band to improve the driving efficiency between a sonar transmitter and a transducer. This paper used the PSO (particle swarm optimization) algorithm to estimate electrical equivalent circuit parameters of a transducer that has multiple resonant modes. The proposed method used a new fitness function to minimize the estimation error between the measured impedance of the transducer and the estimated impedance. The difference to the previous method is that the proposed method considered interference effects of the adjacent resonant modes. Ad-ditionally, this paper analyzed the effective power and separated the mechanical and acoustical resistance by considering the acoustic radiation efficiency of the transducer. As a result, the proposed method estimated all parameters at the resonance points which are influenced by the adjacent resonant modes. ? 2021 by the authors. Licensee MDPI, Basel, Switzerland.11Nsciescopu
Microwave plasma generation with resonance frequency tracking and power regulation
No full textThis paper presents a palm-sized power-providing module for microwave plasma generation with resonancefrequency tracking and output-power-regulation schemes. A 2.4-GHz coaxial transmission line resonator is used as a microwave plasma generator. The power module covers the frequency range from 2.3 to 2.5 GHz with the maximum power capability of 24 W. The power module adaptively sets the output frequency so that the forward power to the resonator is minimally reflected in response to the resonance frequency shift due to plasma formation. At a forward input power of 2 W, the resonance frequency shift by plasma formation is 41 MHz. With the proposed adaptive frequency tracking scheme, the power-transfer efficiency improves from 56 to 88 %. In addition, production of ��OH radical, which is one of the key species in biomedical applications, increases by 33 % at 2 W. The power regulation function is verified by measuring the plasma gas temperature, which is an important indicator of safety for biomedical applications. With a feedback loop control, the power module stably generates 1 W and maintains a constant plasma gas temperature of 40 ��C for 300 s. The measurements reveal that the proposed schemes can improve the power efficiency and controllability of microwave plasma generation, and thereby increase the feasibility of producing a portable low-power microwave bio-plasma device. ? 2017 IEEE.11sciescopu
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
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
An ultrasonic scanner to probe 3-D finger skin structures for biometric recognition
No full textTo use the three-dimensional (3-D) structure of finger skin for personal identification, a 3-D ultrasonic finger skin scanner is implemented by combining a commercial 25 MHz ultrasound transducer, a three-axis motor system, an analog-to-digital converter a field-programmable gate array, a Universal Serial Bus 3.0 interface, and a PC. The scanner was successfully applied to monitoring the deep-layer pattern 1500 μm below the surface of an artificial finger module, as well as the surface fingerprint pattern, with an axial resolution of 123 μm. The Hilbert transform and 50x interpolation were performed on the received ultrasound data to enhance the axial and lateral resolutions, respectively. B-mode and C-mode imaging and a contour plot were presented for the surface fingerprint and the deep-layer pattern. © 2019 Institute of Electronics and Information Engineers. All rights reserved.11Nscopuskc
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
Fully differential ROIC for SNR enhancement by using a MEMS microphone pair with a differential AC bias and a high-voltage DC bias
No full textA fully differential readout integrated circuit (ROIC) is proposed to enhance SNR by using a micro electro mechanical system (MEMS) microphone pair. A differential clock is AC-coupled to the MEMS microphone pair as AC bias for chopper operation, while maintaining a high-voltage DC bias through high-resistance resistors for high sensitivity. The MEMS microphone pair connected to the fully differential ROIC amplifier with a demodulation chopper increased the measured SNRAW by 3.5~4.3dB compared to a single MEMS microphone with a chopper. The chopper operation applied to the pair of MEMS microphones reduced the measured audio band noise at the ROIC output by 14.8~16.5 times, compared to the no-chopper case. The fully differential ROIC consists of an amplifier, a demodulation chopper, a pair of resistor-capacitor low pass filters (RC-LPFs) and a unity-gain buffer. The ROIC implemented in a 0.35��m CMOS process takes a chip area of 2.5mm2 and consumes 134��A at a supply voltage of 3.3V. Copyrights ? 2020 The Institute of Electronics and Information Engineers11Nscopuskc
A low-power LDO circuit with a fast load regulation
No full textBy adding a Miller frequency compensation to the conventional LDO circuit that combines the super source follower and the voltage spike detection, a low-power LDO circuit is proposed to drive the load capacitance up to 10 pF with a fast load regulation. The LDO circuit converts a 5 V input to a 3.3V output, consumes 26 ��A, and settles in 75 ns at a 10 mA load current step in 1ns. ? 2016 IEEE.11Nscopu
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