The Experts below are selected from a list of 43527 Experts worldwide ranked by ideXlab platform
Anthony Grbic - One of the best experts on this subject based on the ideXlab platform.
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a lumped element unit cell for beam forming networks and its application to a miniaturized butler matrix
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Erio Gandini, Mauro Ettorre, Ronan Sauleau, Anthony GrbicAbstract:A lumped-element unit cell for designing compact beam-forming networks (BFNs) is proposed. It is a reciprocal four-port network, which is lossless, isolated, and matched at all ports. The unit cell is designed to behave as planar and compact directional couplers with both arbitrary Output Amplitude and phase distributions, as well as crossovers with arbitrary Output phase distributions. For both cases, design equations are derived. The design procedure is validated numerically and experimentally through several examples. The versatility of the unit cell allows the design of BFNs using only the proposed network topology. As an example, a 4 $\,\times\,$ 4 Butler matrix is implemented. A strong size reduction is also achieved with respect to classical designs thanks to the lumped-element implementation. The prototype footprint is approximately 25 times smaller than typical transmission-line-based Butler matrices. The structure shows also a very small area compared to state-of-the-art miniaturized 4 $\,\times\,$ 4 Butler matrix designs. Measurement results confirm the behavior of the Butler matrix as a BFN. The achieved bandwidth is approximately 8%.
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a lumped element directional coupler with arbitrary Output Amplitude and phase distributions
International Microwave Symposium, 2012Co-Authors: Erio Gandini, Mauro Ettorre, Ronan Sauleau, Anthony GrbicAbstract:A directional coupler with arbitrary Output Amplitude and phase distributions is proposed. Design equations and experimental results are presented and compared with numerical simulations. During the presentation, the use of the coupler as a building block for a Butler matrix will be shown. The proposed coupler achieves a significant size reduction over conventional couplers. It is five times smaller than a classical branchline coupler, and may provide an attractive solution for applications that require size reduction.
Ana Ruiz-rodríguez - One of the best experts on this subject based on the ideXlab platform.
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Ultrasound assisted extraction of phenolic compounds from grapes.
Analytica chimica acta, 2011Co-Authors: Ceferino Carrera, Ana Ruiz-rodríguezAbstract:Abstract A new ultrasound-assisted extraction method was developed for the determination of phenolic compounds present in grapes. Several extraction variables including extraction temperature (0–75 °C), Output Amplitude (20, 50 and 100%), duty cycle (0.2 s, 0.6 s and 1 s), the quantity of sample (0.5–2 g), and the total extraction time (3–15 min) were evaluated. One of the most widely used extraction methods of polyphenol extraction has been used as reference method. Three parameters were compared: total amount of phenolic compounds, total amount of anthocyanins and total amount of tannic components. The resulting method produced similar or higher recoveries for these three parameters; however a much shorter extraction time was needed: 6 min (ultrasound assisted extraction method) instead of 60 min (reference method). Analytical properties for the new method were established, including limit of detection, limit of quantification, repeatability and reproducibility. The developed method was applied to two different types of grapes in different ripening degree.
M Luque D De Castro - One of the best experts on this subject based on the ideXlab platform.
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ultrasound assisted extraction of phenolic compounds from strawberries prior to liquid chromatographic separation and photodiode array ultraviolet detection
Journal of Chromatography A, 2005Co-Authors: M C Herrera, M Luque D De CastroAbstract:Abstract Ultrasound-assisted extraction was used for the determination of phenolic compounds present in strawberries. The optimization study of the extraction was carried out using spiked samples (100 mg/kg). The sample immersed in an aqueous solution containing hydrochloric acid (0.4 M) was sonicated for 2 min (duty cycle 0.2 s, Output Amplitude 20% of the nominal Amplitude of the converter, applied power 100 W with the probe placed 1 cm from the bottom of the water bath and 5 cm from the walls of the precipitate glass). Subsequent separation was carried out by liquid chromatography (LC) with photodiode array UV detection. Calibration curves using the standard addition in green strawberries typically gave linear dynamic ranges of 2–300 mg/l for all analytes; R 2 values exceeded 0.996 in all cases. The method was applied to two types of strawberries to demonstrate the applicability of the proposed method, which is much faster and produces less analyte degradation than methods as solid–liquid, subcritical water and microwave-assisted extraction.
Shuting Liu - One of the best experts on this subject based on the ideXlab platform.
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switchable textile triboelectric nanogenerators s tengs for continuous profile sensing application without environmental interferences
Nano Energy, 2020Co-Authors: Shuting Liu, Hao Wang, Shurong Dong, Chengkuo LeeAbstract:Abstract Conventionally, the Output Amplitude of triboelectric nanogenerators (TENGs) sensors is detected as the sensing Output, where the accuracy and stability are easily affected by environmental interferences such as humidity, temperature and electrostatic coupling with surrounding objects. Meanwhile, the nature of pulse mode voltage Output cannot provide information to further generate a detailed profile of the varying force with time interval when users press a typical TENG working in the contact-separation mode. These two critical issues hinder the TENGs sensors to be competitive with conventionally commercialized sensors. In this study, a switchable textile-triboelectric nanogenerator (S-TENG) is proposed to address these issues. By working on a switchable mode to generate resistor-capacitor (RC) discharging voltage, i.e, enabling capacitive sensing, the capacitance of the TENGs device is not affected by environmental interferences. Moreover, a high-frequency switching approach is investigated to generate a continuous profile of time-dependent capacitance as a function of force along time, referring to the continuous sensing parameter. Therefore, S-TENGs offer the sensory information which could not be achieved by any other TENGs so far.
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a switchable fabric triboelectric nanogenerators sf tengs profile sensing application
2019 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), 2019Co-Authors: Hao Wang, Shuting Liu, Shurong Dong, Chengkuo LeeAbstract:Conventionally, the Output Amplitude of TENGs sensors is detected as the sensing Output, where the accuracy and stability are easily affected by environmental interferences such as humidity, temperature and electrostatic coupling with surrounding objects. Meanwhile, the nature of pulse mode voltage Output cannot provide information to further generate detailed profile of force variation along time interval when users press a typical TENG working in contact-separation mode. These two critical issues stop the TENGs sensors to be competitive with conventionally commercialized sensors.In this study, a switchable textile-triboelectric nanogenerator (S-TENG) is proposed to offer a solution for these issues. By working on a switchable mode to generate RC discharging voltage, i.e, enabling capacitive sensing, the capacitance of TENGs devices is not affected by environmental interferences. Moreover, a high-frequency switching approach is investigated to generate a continuous profile of time-dependent capacitance change as a function of force variation along time, referring to the continuous sensing parameter. Therefore, S-TENGs offer the sensory information which could not be achieved by any other TENGs so far.
Erio Gandini - One of the best experts on this subject based on the ideXlab platform.
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a lumped element unit cell for beam forming networks and its application to a miniaturized butler matrix
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Erio Gandini, Mauro Ettorre, Ronan Sauleau, Anthony GrbicAbstract:A lumped-element unit cell for designing compact beam-forming networks (BFNs) is proposed. It is a reciprocal four-port network, which is lossless, isolated, and matched at all ports. The unit cell is designed to behave as planar and compact directional couplers with both arbitrary Output Amplitude and phase distributions, as well as crossovers with arbitrary Output phase distributions. For both cases, design equations are derived. The design procedure is validated numerically and experimentally through several examples. The versatility of the unit cell allows the design of BFNs using only the proposed network topology. As an example, a 4 $\,\times\,$ 4 Butler matrix is implemented. A strong size reduction is also achieved with respect to classical designs thanks to the lumped-element implementation. The prototype footprint is approximately 25 times smaller than typical transmission-line-based Butler matrices. The structure shows also a very small area compared to state-of-the-art miniaturized 4 $\,\times\,$ 4 Butler matrix designs. Measurement results confirm the behavior of the Butler matrix as a BFN. The achieved bandwidth is approximately 8%.
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a lumped element directional coupler with arbitrary Output Amplitude and phase distributions
International Microwave Symposium, 2012Co-Authors: Erio Gandini, Mauro Ettorre, Ronan Sauleau, Anthony GrbicAbstract:A directional coupler with arbitrary Output Amplitude and phase distributions is proposed. Design equations and experimental results are presented and compared with numerical simulations. During the presentation, the use of the coupler as a building block for a Butler matrix will be shown. The proposed coupler achieves a significant size reduction over conventional couplers. It is five times smaller than a classical branchline coupler, and may provide an attractive solution for applications that require size reduction.
