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51.
AC-coupled front-end for biopotential measurements 总被引:5,自引:0,他引:5
Spinelli EM Pallàs-Areny R Mayosky MA 《IEEE transactions on bio-medical engineering》2003,50(3):391-395
AC coupling is essential in biopotential measurements. Electrode offset potentials can be several orders of magnitude larger than the amplitudes of the biological signals of interest, thus limiting the admissible gain of a dc-coupled front end to prevent amplifier saturation. A high-gain input stage needs ac input coupling. This can be achieved by series capacitors, but in order to provide a bias path, grounded resistors are usually included, which degrade the common mode rejection ratio (CMRR). This paper proposes a novel balanced input ac-coupling network that provides a bias path without any connection to ground, thus resulting in a high CMRR. The circuit being passive, it does not limit the differential dc input voltage. Furthermore, differential signals are ac coupled, whereas common-mode voltages are dc coupled, thus allowing the closed-loop control of the dc common mode voltage by means of a driven-right-leg circuit. This makes the circuit compatible with common-mode dc shifting strategies intended for single-supply biopotential amplifiers. The proposed circuit allows the implementation of high-gain biopotential amplifiers with a reduced number of parts, thus resulting in low power consumption. An electrocardiogram amplifier built according to the proposed design achieves a CMRR of 123 dB at 50 Hz. 相似文献
52.
53.
Concepción Vidal-Valverde M. Carmen Martin-Villa Josefa Herranz Enrique Rojas-Hidalgo 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1981,172(2):93-95
Summary The sugar content of fourteen soft drinks amply consumed in Spain has been determined by high performance liquid chromatography (HPLC). The method, fast and reliable requires a minimum of sample preparation. For the total sugar content, a comparison is made with the classical column chromatography.
Bestimmung von Kohlenhydraten in Erfrischungsgetränken durch Hochdruckflüssigkeitschromatographie
Zusammenfassung Der Zuckergehalt von vierzehn Erfrischungsgetränken, deren Verbrauch in Spanien sehr groß ist, wurde durch die Hochdruckflüssigkeitschromatographie (HPLC) festgestellt. Diese schnelle und zuverlässige Methode erfordert ein Minimum an Vorbereitungen. Für den gesamten Zuckergehalt wird ein Vergleich mit der klassischen Säulenchromatographie durchgeführt.相似文献
54.
Juan Manuel Enrique Jos Manuel Andújar Eladio Durn Miguel Angel Martínez 《Progress in Photovoltaics: Research and Applications》2015,23(12):1940-1955
This paper presents a new, simple, accurate, and inexpensive practical methodology and experimental solution for the modeling of conventional (domestic and commercial facilities) photovoltaic generators (PVG), so that they can work at their maximum power point (MPP). The PVG may be a panel, an array of panels, or a photovoltaic field. As a starting restriction (actual) it has to be assumed that it is not possible to isolate the PVG variables dependence (mainly current, voltage, and hence power) with solar radiation and temperature, because they are highly correlated. This methodology proposes the modeling facility on its MPP by its MPP resistance (RMPP = VMPP/IMPP), being VMPP and IMPP the voltage and current of the PVG, respectively, at its MPP. The analysis shows, by simulation first and then experimentally, that RMPP does not present significant temperature dependencies, at least in the usual range. This important result allows us to model the PVG only in terms of solar radiation. From a set of experimental data, different models to estimate RMPP are proposed. The obtained results are very accurate. These models allow an immediate practical application that it is also developed in the paper: MPP tracker (MPPT) design by the calculation of the DC/DC converter duty cycle which places the PVG at its MPP directly and continuously. This new methodology and experimental system has been registered in the Spanish Patent and Trademark Office with the number P201530352. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
55.
Enrique Del Castillo Douglas C. Montgomery 《Quality and Reliability Engineering International》1996,12(3):157-157
The first two tables in Reference 1 are incorrect. Corrected tables are provided below. The errors do not affect the conclusions or the discussion in that paper. 相似文献
56.
To evaluate the oxidation behavior of high-burnup advanced fuel cladding tubes in high-temperature steam, laboratory-scale isothermal oxidation tests were conducted using the following advanced fuel cladding tubes with burnups of up to 85 GWd/t: M-MDATM, low-tin ZIRLOTM, M5®, and Zircaloy-2 (LK3). These oxidation tests were performed in steam-flowing conditions at temperatures ranging from 1173 to 1473 K for durations between 120 and 4000 s, and the oxidation kinetics was evaluated. The oxidation kinetics of the high-burnup advanced fuel cladding tube specimens estimated by assuming the parabolic rate law was comparable to or slower than that of the unirradiated Zircaloy-4 cladding tube specimens reported in a previous study. It is considered that the protective e?ect of the corrosion layer hindered oxidation. Furthermore, no increase in the oxidation kinetics because of the pre-hydriding was observed. The onset times of the breakaway oxidations of these cladding tube specimens were comparable to those of the unirradiated Zircaloy-4 cladding tubes reported in previous studies. Therefore, it is considered that the burnup extension up to 85 GWd/t and the use of the advanced fuel cladding tubes do not significantly increase the oxidation kinetics and do not significantly reduce the onset time of the breakaway oxidation. 相似文献
57.
58.
The rates of CO and CO/CO2 hydrogenation at 4.2 MPa and 523 K are reported for a series of Cu/SiO2 catalysts containing 2 to 88 wt.% Cu. These catalysts were prepared on a variety of silica sources using several different Cu deposition techniques. In CO/CO2 hydrogenation, the rate of methanol formation is proportional to the exposed Cu surface area of the reduced catalyst precursor, as determined by N2O frontal chromatography. The observed rate, 4.2×10–3 mole CH3OH/Cu site-sec, is within a factor of three of the rates reported by others over Cu/ZnO and Cu/ZnO/Al2O3 catalysts under comparable conditions. These results suggest that the ZnO component is only a moderate promoter in methanol synthesis. Hydrogenation of CO over these catalysts also gives methanol with high selectivity, but the synthesis rate is not proportional to the Cu surface area. This implies that another type of site, either alone or in cooperation with Cu, is involved in the synthesis of methanol from CO. 相似文献
59.
de Diego Isaac Martín Román Ignacio San Montero Javier Cano Conde Cristina Cabello Enrique 《Multimedia Tools and Applications》2019,78(13):17437-17459
Multimedia Tools and Applications - This paper presents a novel distributed intelligent video surveillance architecture based on Wireless Multimedia Sensor Networks (WMSNs). This architecture is... 相似文献
60.
Yutaka Udagawa Takeshi Mihara Tomoyuki Sugiyama Motoe Suzuki Masaki Amaya 《Journal of Nuclear Science and Technology》2013,50(2):208-219
A continuum damage mechanics model using FEM calculations was proposed to be applied to an analysis of the fuel failure due to pellet cladding mechanical interaction (PCMI) under reactivity-initiated accident conditions. The model expressed ductile fracture via two processes: damage nucleation related to void nucleation and damage evolution related to void growth and linkage. The boundary conditions for the simulations were input from the fuel performance codes FEMAXI-7 and RANNS. The simulation made reasonable predictions for the cladding hoop strain at failure and reproduced the typical fracture behavior of the fuel cladding under the PCMI loading, characterized by a ductile shear zone in the inner region of the cladding wall. It was shown that occurrence of a through-wall crack is determined at an early stage of crack propagation, and the rest of the through-wall penetration process is achieved with a negligible increment in strain. The effect of a local temperature rise in the cladding inner region on the failure strain was found to be less than 5% for the conditions investigated. Failure strains predicted under a plane strain loading were smaller by 20%–30% than those predicted under equibiaxial tensions between the hoop and the axial directions. 相似文献