Academic literature on the topic 'Low power excitation source'
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Journal articles on the topic "Low power excitation source"
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Wang, Yong Qing, Na Chong, Li Mei Dong, Yu Jun Tang, and Hai Jun Song. "Study on Electronic Excitation Temperature of Argon Plasma Using Low Pressure Micro-ICP Excitation Source." Advanced Materials Research 383-390 (November 2011): 1844–48. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.1844.
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Electronic excitation temperature is an important indicator of the spectrometer excitation source. This work experimented self-made micro-ICP excitation spectroscopy based on PCB technology, and detected 17 spectral lines in 690~860 nm of argon atom. 763.51 nm and 772.42 nm spectral lines whose wavelengths are close to were used to calculate electronic excitation temperature of argon excited by micro-ICP, and results show in 1600~3000 K. Experimental test data shows effects of argon gas pressure on electronic excitation temperature that in 20~210 Pa electronic excitation temperature increases with pressure on the whole. When argon pressure is greater than 220 Pa, plasma flame flickers and the electronic excitation temperature shows greater fluctuation; Experimental test shows effects of RF power on electronic excitation temperature that in 3~23 W electronic excitation temperature gradually increases with RF power. Causes of electronic excitation temperature with pressure, RF power variation are analyzed.
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Allen, G. Mark, and David M. Coleman. "Characterization of a Dual Inductively Coupled Plasma Atomic Emission Source." Applied Spectroscopy 41, no. 3 (March 1987): 381–87. http://dx.doi.org/10.1366/0003702874449039.
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A dual inductively copuled plasma atomic emission spectroscopic system is described. This new analytical discharge segregates the normally integrated processes of sampling and spectral excitation associated with atomic emission sources. A low-power, low-argon-flow, radio-frequency plasma is used as a sampling device to create gaseous species from liquid and solid samples which are subsequently transported to a second plasma for excitation. Design and construction of instrumentation and associated operational parameters are reviewed. Comparisons of the sampling and the excitation plasmas include spatial emission profiles, linear calibration plots, signal-to-background ratios, and analytical detection limits. Use of the dual ICP for direct analysis of particulates (coal fly ash and firebrick) is demonstrated.
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Abolmasov, P. K., S. N. Fabrika, and O. N. Sholukhova. "The optical counterpart of the ultraluminous X-ray source NGC6946 ULX-1." Proceedings of the International Astronomical Union 2, S238 (August 2006): 229–32. http://dx.doi.org/10.1017/s1743921307005029.
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AbstractWe present a study of a peculiar nebula MF16 associated with an Ultraluminous X-ray Source NGC6946 ULX-1. We use integral-field and long-slit spectral data obtained with the 6-m telescope (Russia). The nebula was for a long time considered powered by strong shocks enhancing both high-excitation and low-excitation lines. However, kinematical properties point to rather moderate expansion rates (VS ∼ 100÷200 km s−1). The total power of the emission-line source exceeds by one or two orders of magnitude the power observed expansion rate can provide, that points towards the existence of an additional source of excitation and ionization. Using CLOUDY96.01 photoionization code we derive the properties of the photoionizing source. Its total UV/EUV luminosity must be about 1040 erg/s.
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Zhou, Fen Ping, Yang Jiao, and Hui Juan Duan. "Design of Excitation Source for Ultrasonic Guided Waves Based on DDS Technology." Advanced Materials Research 1049-1050 (October 2014): 674–77. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.674.
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According to the characteristics of ultrasonic guided wave inspection, An exciting power, used for exciting ultrasonic guided waves in pipeline is designed based on DDS and FPGA. The excitation source consists of FPGA, D/A conversion circuit, a low-pass filter circuit and power amplifier circuit. Constructing DDS based on FPGA as the controller and signal generator. Filter circuit and power amplifier circuit are designed in this paper. The experiment results show that the excitation source can have high voltage and high frequency output capability, and can generate desired signal type with a good accuracy to fit the requirements in practice. It can be conveniently used for pipeline ultrasonic guided wave detection.
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Leonard, James D., Gen Katagiri, and Terry L. Gustafson. "Quasi-Continuous Generation of 211-nm Excitation for Resonance Raman Spectroscopy." Applied Spectroscopy 48, no. 4 (April 1994): 489–92. http://dx.doi.org/10.1366/000370294775268901.
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We demonstrate the generation of 211-nm radiation using sum frequency mixing of the second and third harmonics of a cw mode-locked Nd: YLF laser operating at 76 MHz as an excitation source for resonance Raman spectroscopy. Owing to the relatively low peak power (∼4 W) but high average power (∼8 mW), we obtain good-quality spectra with relatively short collection times. In order to demonstrate the utility of this source, we have obtained the Raman spectra of several biological molecules and an inorganic molecule, ruthenium trisbipyridine, using 211-nm excitation.
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Wang, Yong Qing, Na Chong, Rong Xia Sun, Ying Chang Zhou, and Wen Jun Chen. "Study on Start Burning Performance of Micro-ICP Using Stereo Spiral Coil." Advanced Materials Research 383-390 (November 2011): 390–94. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.390.
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According to the problem of low energy utilization of plane spiral coil used in micro-ICP, a kind of micro stereo helical coil was designed. Made 24 different structural parameters of stereo spiral coil whose diameter range 3~10 mm. Using comprehensive experimental method tested different parameters’ coils inspire argon plasma. In 13.56MHz RF power, relationships between argon pressure, coil turns, coil diameter and combustion /maintaining power of micro-ICP excitation source were tested. From spectrometer observed 17 argon emission spectrum in 690~860 nm. Spectral lines intensity influenced by RF power and work pressure. Experiments proved that micro-ICP excitation source using stereo helical coil is feasible. It can form Ar plasma and inspire Ar spectral lines.
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Xie, Xinying, Kaiqi Chen, Zhichao Zhou, Wei Jiang, Yuqi Wang, Sisi Wang, Zhihe Xia, and Man Wong. "P‐1.4: Oxygen‐Plasma Induced Generation of Mobile Charge Carriers in Indium‐Tin‐Zinc Oxide." SID Symposium Digest of Technical Papers 54, S1 (April 2023): 448–50. http://dx.doi.org/10.1002/sdtp.16328.
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Mobile charge carriers can be generated in indium‐tinzinc oxide (ITZO) covered with a silicon oxide layer when subjected to an oxygen plasma treatment. The resulting resistivity is sensitive to the thickness of the cover oxide, the plasma excitation power, and the treatment time. With 280 nm of cover oxide and 10 mins of treatment, a low resistivity of 1.2 mΩ∙cm can be obtained in a plasma biased with a radio frequency excitation power of 100 W and an inductively coupled plasma excitation power of 2000 W. The treatment has been deployed to form the source/drain regions of a self‐aligned, top‐gate ITZO thin‐film transistor.
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Deng, Yujia, Wen Zeng, Xiaoming Jiang, and Xiandeng Hou. "Portable photochemical vapor generation-microwave plasma optical emission spectrometer." Journal of Analytical Atomic Spectrometry 35, no. 7 (2020): 1316–19. http://dx.doi.org/10.1039/d0ja00104j.
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A low power microwave plasma torch as an excitation source was combined with a photochemical vapor generator (PVG) and a miniaturized charge-coupled device to construct a portable optical emission spectrometer.
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Higashino, Kohta, Naoki Okamura, Teruyoshi Sasayama, and Takashi Yoshida. "Application of square-wave inverter in excitation system for magnetic nanoparticle tomography." AIP Advances 12, no. 3 (March 1, 2022): 035012. http://dx.doi.org/10.1063/9.0000266.
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To collect the signals of magnetic nanoparticles (MNPs) at a distance from a magnetic nanoparticle tomography, a strong ac magnetic field should be generated by applying a high current to the excitation coil. To this end, sinusoidal excitation using a linear amplifier-type ac power source has been applied to the tomography. Although this source can provide a high-quality sinusoidal voltage, its low power efficiency is not suitable for generating the required high current. To overcome this limitation, we use an H-bridge voltage source inverter to achieve high efficiency by generating a square-wave voltage. However, the third harmonic component in the square wave, undermines the acquisition of MNP signals. Thus, we suppress the third harmonic by shifting the switching phase of the inverter transistors. As a result, the third harmonic in the excitation current is reduced to less than one-tenth of that obtained after conventional suppression. We verify the distribution of MNP signals at depths up to 50 mm using the proposed excitation approach. The results demonstrate the effectiveness of the proposed approach based on square-wave inverter excitation for magnetic nanoparticle tomography.
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Bodduluri, Mani Teja, Torben Dankwort, Thomas Lisec, Sven Grünzig, Anmol Khare, Minhaz Ahmed, and Björn Gojdka. "Fully Integrated High-Performance MEMS Energy Harvester for Mechanical and Contactless Magnetic Excitation in Resonance and at Low Frequencies." Micromachines 13, no. 6 (May 30, 2022): 863. http://dx.doi.org/10.3390/mi13060863.
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Energy harvesting and storage is highly demanded to enhance the lifetime of autonomous systems, such as IoT sensor nodes, avoiding costly and time-consuming battery replacement. However, cost efficient and small-scale energy harvesting systems with reasonable power output are still subjects of current development. In this work, we present a mechanically and magnetically excitable MEMS vibrational piezoelectric energy harvester featuring wafer-level integrated rare-earth micromagnets. The latter enable harvesting of energy efficiently both in resonance and from low-g, low-frequency mechanical energy sources. Under rotational magnetic excitation at frequencies below 50 Hz, RMS power output up to 74.11 µW is demonstrated in frequency up-conversion. Magnetic excitation in resonance results in open-circuit voltages > 9 V and RMS power output up to 139.39 µW. For purely mechanical excitation, the powder-based integration process allows the realization of high-density and thus compact proof masses in the cantilever design. Accordingly, the device achieves 24.75 µW power output under mechanical excitation of 0.75 g at resonance. The ability to load a capacitance of 2.8 µF at 2.5 V within 30 s is demonstrated, facilitating a custom design low-power ASIC.
Dissertations / Theses on the topic "Low power excitation source"
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Roy, Sajib, and Md Murad Kabir Nipun. "Understanding Sub-threshold source coupled logic for ultra-low power application." Thesis, Linköpings universitet, Elektroniksystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69404.
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This thesis work primarily focuses on the applicability of sub-threshold source coupled logic (STSCL) for building digital circuits and systems that run at very low voltage and promise to provide desirable performance with excellent energy savings. Sectors like bio-engineering and smart sensors require the energy consumption to be effectively very low for long battery life. Alongside meeting the ultra-low power specification, the system must also be reliable, robust, and perform well under harsh conditions. In this thesis work, logic gates are designed and analyzed, using STSCL. These gates are further used for implementation of digital subsystems in small-sized smart dust sensors which would operate at very low supply voltages and consume extremely low power. For understanding the performance of STSCL with respect to ultra-low power and energy; a seven-stage ring oscillator, a 4-by-4 array multiplier, a fifth-order FIR filter and finally a fifty-fifth-order FIR filter were designed. The subcircuits and systems have been simulated for different supply voltages, scaling down to 0.2 V, at different temperature values (-20oC and 70oC) in both 45 nm and 65 nm process technologies. The chosen architectures for the FIR filters and array multiplier were conventional and essentially taken from traditional CMOS-based designs. The simulated results are studied, analyzed and compared with same CMOS-based digital circuits. The results show on the advantage of STSCL-based digital systems over CMOS. Simulation results provide an energy consumption of 1.1388 nJ for a fifty-fifth-order FIR filter, at low temperatures (-20oC), using STSCL logic, which is comparatively less than for the corresponding CMOS logic implementation.
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González, Fernández Ernesto. "Low-power techniques for wireless gas sensing network applications: pulsed light excitation with data extraction strategies." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672792.
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Aquesta tesi està enfocada en dues línies d'investigació. La primera aborda el desenvolupament d'una metodologia
basada en llum polsada per modulació de sensors químic-resistius per a l'extracció d'informació del senyal transitòri, i
la segona planteja la implementació d'una xarxa sense fils de sensors (WSN) basada en tecnologia LoRa per al
monitoratge de la qualitat de l'aire (AQM) i la detecció d'esdeveniments de fuita de gasos. Aquest document està
estructurat en quatre capítols organitzats de la següent manera: el Capítol 1 presenta l'estat de l'art, una introducció
als mecanismes de millora de l'comportament dels sensors químic-resistius, així com una introducció a la
implementació de xarxes sense fils de sensors per a la monitorització de la qualitat de l'aire; el Capítol 2 està compost
pels dos articles publicats relacionats amb la metodologia basada en la modulació utilitzant llum polsada per a
l'extracció d'informació del senyal transitòria de sensors químic-resistius; el Capítol 3 presenta l'article publicat
relacionat amb la implementació d'una WSN per a AQM; el Capítol 4 presenta les conclusions derivades dels resultats
obtinguts durant el desenvolupament de el projecte de tesi i les recomanacions per al treball futur associat a la
continuïtat dels principals resultats d'aquesta tesiLa presente tesis está enfocada en dos líneas de investigación, La primera aborda el desarrollo de una metodología basada en luz pulsada para modulación de sensores químico-resistivos para la extracción de información de la señal transitoria; y la segunda plantea la implementación de una red inalámbrica de sensores (WSN) basada en tecnología LoRa para la monitorización de la calidad del aire (AQM) y la detección de eventos de fuga de gases. Este documento está estructurado en cuatro capítulos organizados de la siguiente forma: el Capítulo 1 presenta el estado del arte, una introducción a los mecanismos de mejora del comportamiento de los sensores químico-resistivos, así como una introducción a la implementación de redes inalámbricas de sensores para la monitorización de la calidad del aire; el Capítulo 2 está compuesto por los dos artículos publicados relacionados con la metodología basada en la modulación utilizando luz pulsada para la extracción de información de la señal transitoria de sensores químico-resistivos; el Capítulo 3 presenta el artículo publicado relacionado con la implementación de una WSN para AQM; el Capítulo 4 presenta las conclusiones derivadas de los resultados obtenidos durante el desarrollo de el proyecto de tesis y las recomendaciones para el trabajo futuro asociado a la continuidad de los principales resultados de esta tesis.
The present thesis project is focused in two different yet related research lines. The first one addresses the development of a pulsed light-based chemiresistive sensor modulation methodology for transient information extraction. The second research line developed deals with the implementation of a LoRa-based portable, scalable, low-cost, and low power Wireless Sensor Network (WSN) for Air Quality Monitoring (AQM) and gas leakage events detection. This document is structured in four Chapters organized as follows: Chapter 1 presents the state of the art, an introduction to sensing performance enhancement and transient data extraction methods, as well as an introduction to the implementation of WSN for AQM; Chapter 2 is composed of the two published paper related to the pulsed light modulation methodology for transient information extraction; Chapter 3 presents the published paper related to the implementation of a LoRa-based WSN for AQM; Chapter 4 states the conclusions derived from the results obtained during this thesis project and the recommendations for the future work associated to the continuity of this thesis findings.
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Bicer, Nazan. "A Current Source Converter Based Statcom For Reactive Power Compensation At Low Voltage." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/2/12612007/index.pdf.
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This research work is devoted to the analysis, design and development of the Current-Source Converter (CSC) based distribution-type Static Synchronous Compensator (D-STATCOM) for low-voltage applications in reactive-power control in order to achieve i) faster transient response in reactive-power control, ii) lower current harmonic distortion, iii) lower power losses and iv) minimum storage elements in comparison with conventional solutions. The developed CSC-D-STATCOM includes a low-pass input filter and a three phase forced-commutated CSC which is composed of six insulated gate bipolar transistors (IGBT) with built-in series diodes. The analysis and the control of the CSC-D-STATCOM are carried out in dq-synchronous reference frame in order to obtain the reference current waveform which is to be generated by switching the IGBTs at 3kHz with the use of space vector modulation.
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Ordóñez, Hurtado Andrés Fernando. "Design methodology of a modular CMOS ultra-low power self-biased current source." reponame:Repositório Institucional da UFSC, 2017. https://repositorio.ufsc.br/xmlui/handle/123456789/178587.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2017.Made available in DSpace on 2017-08-22T04:25:03Z (GMT). No. of bitstreams: 1 347153.pdf: 5611883 bytes, checksum: ffcc82f51f6a3197acb623b2af028078 (MD5) Previous issue date: 2017
Neste documento é desenvolvida uma metodologia de projeto de uma fonte de corrente auto polarizada de ultra baixo consumo de potência em tecnologia CMOS. É descrita uma topologia modular implementada com dois MOSFETs auto cascodados (SCMs) e um amplificador operacional. A metodologia proposta está baseada no conceito de ni´veis de inversão e o espaço de projeto do circuito é descrito principalmente em termos das especificações do amplificador operacional e do espelho de corrente PMOS. O circuito foi projetado usando uma tecnologia padrão CMOS de 130 nm. Os resultados das simulações são apresentados neste documento para validar a metodologia de projeto e o desempenho da fonte de corrente, mostrando que o circuito proposto pode operar com uma tensão de alimentação menor de 1 V e com menos de 1%/V na regulação de linha.
Abstract : In this document a design procedure of a CMOS ultra-low-power self-biased current source is developed. A modular topology using two self-cascode MOSFETs (SCMs), a current mirror and an operational amplifier is implemented. The described methodology is based on the concept of inversion level, and the design space of the current source is described mainly in terms of the specifications of the operational amplifier and the PMOS current mirror. The circuit was designed in a 130 nm standard CMOS technology. Simulation results are provided to validate the design methodology and the performance of the current source, showing that the proposed circuit can operate at a supply voltage less than 1 V with less than 1%/V of line regulation.
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Amor, Nadia [Verfasser]. "Novel methods and applications of NMR and MRI : low-power RF excitation and hyperpolarized xenon-129 / Nadia Amor." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1021937592/34.
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Lysakowski, Rich. "Development of a low-power molecular microwave plasma and its application as an atom source for atomic spectroscopy." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/51932.
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The major thrusts of this work have been: 1) To develop a high-efficiency low-power TM-010 microwave cavity for nitrogen support gas at atmospheric pressure, 2) To discover and physically characterize potential laser and emission spectroscopic applications of this atom source, with a particular emphasis on laser-induced fluorescence.
The result is the most efficient microwave-induced plasma cavity for nitrogen at one atmosphere that exists to date, giving stable and analytically useful molecular plasmas with only 50 Watts applied power. It is called the “High-Efficiency Molecular Microwave Plasma" (HEMMP) cavity. The HEMMP possesses excellent vaporization and atomization properties. It can handle aqueous sample flows of around 1 mL/min, introduced as an aerosol from a nebulizer. A detection system and sampling system were designed and an analytical instrument was built around the HEMMP cavity. Details of construction, operating conditions and operation of the instrument are described.
Applications investigated include laser-induced fluorescence (LIF), atomic emission spectroscopy (AES), and laser-enhanced ionization (LEI) [also known as the opto-galvanic effect (OGE)]. The major emphasis of the application work has been physical characterization of the low-power nitrogen plasma as an atom source for LIF.
This is the first time that either laser-induced fluorescence or laser-enhanced ionization have been observed and extensively characterized in any microwave-induced plasma (MIP). This is also the first time that atomic emission has been studied in a low-power N₂-MIP. LIF, AES, and LEI signal intensities were studied as a function of applied microwave power, support gas flow rate, signal observation height, and support gas composition using nitrogen and argon mixtures. Results for LIF yielded detection limits in the very low parts per billion range, and for AES in the low parts per billion range. Limit of detection (LOD) and background noise studies were done for all 3 techniques. Signal intensities were measured as a function of laser light intensity for LIF and LEI. Laser saturation was not observed with 300 mW power from the CW dye laser. The effects of electrode geometry and applied electrode voltage on LEI signals were also studied. Extensive background spectral studies were done for the nitrogen plasma.
Analytical feasibility has been demonstrated for AES, LIF, and LEI in the low-power nitrogen MIP. The results presented provide the background physical investigations required for a full-scale development of these techniques for chemical analysis.Ph. D.
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MOSCA, CARMELO. "Methodologies for Frequency Stability Assessment in Low Inertia Power Systems." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2895393.
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Kallel, Bilel. "Design of Inductive Power Transmission System for Low Power Application with Movable Receiver and Large Air Gap." Universitätsverlag Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A32975.
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Inductive power transmission is very useful, not only for systems where energy transfer should take place in hazardous, humid and wet areas, but also for mobile and very small systems. It finds today a widespread use in several fields, such as industry, automotive, medicine and smart buildings. For a good efficiency and a high-power transmission, the sending and the receiving coils should be perfectly aligned and close to each other. A misalignment between the sender and the receiver becomes unavoidable especially for systems with movable parts.
This thesis aims to improve the transmitted power, the mutual inductance, the power at the load, and consequently the power transmission efficiency in case of lateral misalignment between the sending and receiving coils and at large coil-to-coil distance. For this purpose, we adopt a multi input single output (MISO) coil system able to orientate the issued magnetic field to the receiving coil by powering the neighbouring sending coils of the active ones with a weak current in the opposite direction. Furthermore, an analytical model of the used coils and an accurate three-dimensional model of the system have been developed to calculate the induced voltage, the induced current, and the equivalent mutual inductance. Both simulation and experimental results prove that the proposed multi-coil inductive system having an hexagonal arrangement and the sending coils, which have the half diameter of the receiving coil, is able to improve significantly the transmitted power in case of lateral misalignment and big air gap. The novel MISO system reaches better efficiency beginning with an air gap of 50% of the sending coil diameter, and a misalignment of 28% of the sending coil diameter. It reaches the double of the transmitted power of the conventional two-coil inductive system at 50 mm air gap (corresponding to 166% of the sending coil diameter) and at 10 mm lateral misalignment (corresponding to 33% of the sending coil diameter).
In order to improve the equivalent mutual inductance between the primary and secondary sides and to avoid energy losses, we propose a receiver detection method using the sending coils themselves as detectors. Thereby, only the sending coils, under the receiver, are activated and the others remain switched off. For that, the peak of the AC current of the sending coils, is measured and then compared to a detection threshold. The excitation strategy of the active sending coils is optimized corresponding to the receiving coil position. The novel excitation strategy increases the mutual inductance by 85% and the induced voltage by 13% at perfect alignment and by 30% and 10% respectively at 10 mm lateral misalignment, in comparison to the MISO system without a receiver detector and coil-excitation strategy.
In order to increase the transmitted power by resonance, different system topologies have been investigated, such as series-series SS, series-parallel SP, parallel-series PS, and parallel-parallel PP topologies for different levels of load impedance. The results show that a multi-coil inductive system with parallel-parallel PP topology realizes a higher transmitted power than the other topologies for both high and low load impedance values.
The proposed multi-coil inductive system is suitable for low-power systems, such as wireless sensors and biomedical implants, but can be also applied to higher range of power at a flexible position of the receiver.Die induktive Energieübertragung ist interessant, nicht nur für Systeme, bei denen die Energieübertragung in rauen, feuchten und nassen Bereichen erfolgen soll, sondern auch für mobile und sehr kleine Systeme. Diese Art von Energieübertragung findet heute eine breite Anwendung in verschiedenen Bereichen, wie z.B. Industrie, Automobil, Medizin und intelligente Gebäude. Um eine gute Effizienz und eine hohe Energieübertragungsleistung zu realisieren, sollten die Sende- und Empfangsspulen perfekt ausgerichtet und nahe beieinander sein. Insbesondere bei Systemen mit beweglichen Teilen ist jedoch eine Fehlausrichtung zwischen Sender und Empfänger unvermeidlich. Diese Arbeit zielt darauf ab, die übertragene Leistung, die gegenseitige Induktivität, die Leistung an der Last und damit den Wirkungsgrad der Leistungsübertragung im Falle einer seitlichen Fehlausrichtung zwischen Sende- und Empfangsspule und bei großem Abstand von Spule zu Spule zu verbessern. Zu diesem Zweck wird ein Multi-Input Single-Output (MISO)-Spulensystem vorgeschlagen, das in der Lage ist, das ausgegebene Magnetfeld auf die Empfangsspule auszurichten, indem die benachbarten Spulen der aktiven Sendespulen mit einem schwachen Strom in der entgegengesetzten Richtung versorgt wird. Darüber hinaus wurde ein analytisches Modell für die verwendeten Spulen und ein genaues dreidimensionales Modell für das System entwickelt, um die induzierte Spannung, den induzierten Strom und die äquivalente gegenseitige Induktivität zu berechnen. Sowohl die Simulation als auch die experimentellen Ergebnisse belegen, dass das vorgeschlagene induktive Mehrfachspulensystem mit hexagonaler Anordnung und die Sendespulen, die den halben Durchmesser der Empfangsspule haben, in der Lage sind, die Sendeleistung bei lateraler Fehlausrichtung und großem Luftspalt deutlich zu verbessern. Das neuartige MISO-System erreicht einen besseren Wirkungsgrad, beginnend mit einem Luftspalt von 50% des Sendespulendurchmessers und einer Fehlausrichtung von 28% des Sendespulendurchmessers. Sie erreicht bei 50 mm Luftspalt (entspricht 166% des Sendespulendurchmessers) und bei 10 mm seitlichem Versatz (entspricht 33% des Sendespulendurchmessers) das Doppelte der Sendeleistung des herkömmlichen Zwei-Spulen-Induktivsystems. Um die äquivalente gegenseitige Induktivität zwischen Primär- und Sekundärseite zu verbessern und Energieverluste zu vermeiden, schlagen wir ein Verfahren zur Detektion des Empfängers vor, bei dem die Sendespulen selbst als Detektoren verwendet werden. Dabei werden nur die Sendespulen unter dem Empfänger aktiviert und die anderen bleiben ausgeschaltet. Dazu wird der Scheitelwert des Wechselstroms der Sendespulen gemessen und mit einem vorgegebenem Schwellenwert verglichen. Die Anregungsstrategie der aktiven Spulen wird entsprechend der Position der Empfangsspule optimiert. Die neuartige Anregungsstrategie erhöht die gegenseitige Induktivität um 85% und die induzierte Spannung um 13% bei perfekter Ausrichtung und um 30% bzw. 10% bei 10 mm seitlichem Versatz, im Vergleich zum MISO-System ohne Empfängerdetektor und Spulenanregungsstrategie. Um die übertragene Leistung durch Resonanz zu erhöhen, wurden verschiedene Systemtopologien untersucht, wie z.B. Serien-SS, Serien-Parallel-SP, Parallel-Series-PS und Parallel-Parallel-PP-Topologien für verschiedene Stufen der Lastimpedanz. Die Ergebnisse zeigen, dass ein MISO System mit parallel-paralleler PP-Topologie eine höhere Sendeleistung realisiert als die anderen Topologien für hohe und niedrige Last-Impedanzen. Das vorgeschlagene induktive Mehrspulensystem eignet sich für Systeme mit geringer Leistung, wie drahtlose Sensoren und biomedizinische Implantate, kann aber auch flexibler Position des Empfängers in einen höheren Leistungsbereich angewendet werden.
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Ghasemi, Negareh. "Improving ultrasound excitation systems using a flexible power supply with adjustable voltage and frequency to drive piezoelectric transducers." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/61091/1/Negareh_Ghasemi_Thesis.pdf.
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The ability of a piezoelectric transducer in energy conversion is rapidly expanding in several applications. Some of the industrial applications for which a high power ultrasound transducer can be used are surface cleaning, water treatment, plastic welding and food sterilization. Also, a high power ultrasound transducer plays a great role in biomedical applications such as diagnostic and therapeutic applications. An ultrasound transducer is usually applied to convert electrical energy to mechanical energy and vice versa. In some high power ultrasound system, ultrasound transducers are applied as a transmitter, as a receiver or both. As a transmitter, it converts electrical energy to mechanical energy while a receiver converts mechanical energy to electrical energy as a sensor for control system. Once a piezoelectric transducer is excited by electrical signal, piezoelectric material starts to vibrate and generates ultrasound waves. A portion of the ultrasound waves which passes through the medium will be sensed by the receiver and converted to electrical energy. To drive an ultrasound transducer, an excitation signal should be properly designed otherwise undesired signal (low quality) can deteriorate the performance of the transducer (energy conversion) and increase power consumption in the system. For instance, some portion of generated power may be delivered in unwanted frequency which is not acceptable for some applications especially for biomedical applications.
To achieve better performance of the transducer, along with the quality of the excitation signal, the characteristics of the high power ultrasound transducer should be taken into consideration as well. In this regard, several simulation and experimental tests are carried out in this research to model high power ultrasound transducers and systems. During these experiments, high power ultrasound transducers are excited by several excitation signals with different amplitudes and frequencies, using a network analyser, a signal generator, a high power amplifier and a multilevel converter. Also, to analyse the behaviour of the ultrasound system, the voltage ratio of the system is measured in different tests. The voltage across transmitter is measured as an input voltage then divided by the output voltage which is measured across receiver. The results of the transducer characteristics and the ultrasound system behaviour are discussed in chapter 4 and 5 of this thesis.
Each piezoelectric transducer has several resonance frequencies in which its impedance has lower magnitude as compared to non-resonance frequencies. Among these resonance frequencies, just at one of those frequencies, the magnitude of the impedance is minimum. This resonance frequency is known as the main resonance frequency of the transducer. To attain higher efficiency and deliver more power to the ultrasound system, the transducer is usually excited at the main resonance frequency. Therefore, it is important to find out this frequency and other resonance frequencies. Hereof, a frequency detection method is proposed in this research which is discussed in chapter 2.
An extended electrical model of the ultrasound transducer with multiple resonance frequencies consists of several RLC legs in parallel with a capacitor. Each RLC leg represents one of the resonance frequencies of the ultrasound transducer. At resonance frequency the inductor reactance and capacitor reactance cancel out each other and the resistor of this leg represents power conversion of the system at that frequency. This concept is shown in simulation and test results presented in chapter 4.
To excite a high power ultrasound transducer, a high power signal is required. Multilevel converters are usually applied to generate a high power signal but the drawback of this signal is low quality in comparison with a sinusoidal signal. In some applications like ultrasound, it is extensively important to generate a high quality signal. Several control and modulation techniques are introduced in different papers to control the output voltage of the multilevel converters. One of those techniques is harmonic elimination technique. In this technique, switching angles are chosen in such way to reduce harmonic contents in the output side. It is undeniable that increasing the number of the switching angles results in more harmonic reduction. But to have more switching angles, more output voltage levels are required which increase the number of components and cost of the converter. To improve the quality of the output voltage signal with no more components, a new harmonic elimination technique is proposed in this research. Based on this new technique, more variables (DC voltage levels and switching angles) are chosen to eliminate more low order harmonics compared to conventional harmonic elimination techniques. In conventional harmonic elimination method, DC voltage levels are same and only switching angles are calculated to eliminate harmonics. Therefore, the number of eliminated harmonic is limited by the number of switching cycles. In the proposed modulation technique, the switching angles and the DC voltage levels are calculated off-line to eliminate more harmonics. Therefore, the DC voltage levels are not equal and should be regulated. To achieve this aim, a DC/DC converter is applied to adjust the DC link voltages with several capacitors. The effect of the new harmonic elimination technique on the output quality of several single phase multilevel converters is explained in chapter 3 and 6 of this thesis.
According to the electrical model of high power ultrasound transducer, this device can be modelled as parallel combinations of RLC legs with a main capacitor. The impedance diagram of the transducer in frequency domain shows it has capacitive characteristics in almost all frequencies. Therefore, using a voltage source converter to drive a high power ultrasound transducer can create significant leakage current through the transducer. It happens due to significant voltage stress (dv/dt) across the transducer. To remedy this problem, LC filters are applied in some applications. For some applications such as ultrasound, using a LC filter can deteriorate the performance of the transducer by changing its characteristics and displacing the resonance frequency of the transducer. For such a case a current source converter could be a suitable choice to overcome this problem. In this regard, a current source converter is implemented and applied to excite the high power ultrasound transducer. To control the output current and voltage, a hysteresis control and unipolar modulation are used respectively. The results of this test are explained in chapter 7.
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Bouchaala, Dhouha. "Investigation of Current Excitation for Personal Health and Biological Tissues Monitoring." Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-204801.
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Bioimpedance spectroscopy is very useful in biomedical field as a safe and non-invasive technique. A stable and safe excitation current below than 0.5 mA for load impedances changing from 100 Ω to 10 kΩ in the full β-dispersion range from kHz up to 1 MHz is a big challenge for the design of the current source addressed by this thesis. For a good stability and high accuracy, the source should have a high output impedance. Different current source types in “current-mode approach” and “voltage-mode approach” were investigated and compared for usability in bioimpedance measurement systems. The “voltage-mode approach” with grounded load was proven to be more suitable and stable for biomedical measurements. Thereby the Tietze and the Howland circuit in dual configuration with negative feedback have shown the lowest error of the output current and the highest output impedance, where the improved Howland circuit in dual configuration with negative feedback is preferred because it has a simple structure, high accuracy and good stability. We suggest to improve the stability of the Howland circuit in dual configuration with negative feedback by introducing compensated operational amplifiers and to reduce stray capacitances at higher frequencies by adding gain compensation capacitor. We reach thereby an accuracy of 0.5% at low frequency and 0.9% at 1 MHz. With the realized accuracy of the designed voltage controlled current source, one decisive prerequisite for portable bioimpedance measurement system is achieved. In order to select the appropriate excitation signals for short measurement time, a comparative study of signals and their parameters was carried out. It leads to the selection of binary chirp signal as a suitable excitation signal due to its short measurement time about 100 μs, low crest factor lower than 2.8 and an energy efficiency higher than 54% in a very noisy signal. Simulation results show that the designed enhanced Howland current source excited by the binary chirp signal has low error and flatness in the whole rangeDie Bioimpedanzspektroskopie gewinnt aufgrund ihrer besonderen Eigenschaften als nicht-invasive, schonende Messmethode zunehmend an Bedeutung im biomedizinischen Bereich. Dabei ergeben sich besondere erausforderungen für den Entwurf der Stromquelle zur Realisierung eines stabilen und sicheren Anregungsstroms. Gefordert ist eine hohe Genauigkeit bis zu einem Maximalstrom von 0.5 mA in einem Frequenzbereich, der der β-Dispersion entspricht, von wenigen kHz bis hin zu 1 MHz. Die Stabilität muss bei variablen Lastimpedanzen im Bereich von 100 Ω bis 10 kΩ gewährleistet sein. Dafür muss die Stromquelle eine hohe Ausgangsimpedanz aufweisen. Diese Arbeit fokussiert auf den Entwurf von spannungsgesteuerten Stromquellen. Verschiedene Arten von Stromquellen wurden untersucht und verglichen. Der "Voltage-Modus-Ansatz" mit Masse-referenzierter Last hat sich als besser geeignet und stabiler für biomedizinische Messungen erwiesen. Die Tietze-Schaltung und diese Howland-Schaltung zeigen dabei die niedrigsten Fehler des Ausgangsstroms und die höchste Ausgangsimpedanz. Im direkten Vergleich besitzt die verbesserte Howland-Schaltung doch eine einfachere Struktur, höhere Genauigkeit und bessere Stabilität und wird daher gegenüber der Tietze-Schaltung bevorzugt. Um weitere Stabilitätsverbesserungen bei der Howland-Schaltung zu erreichen, werden zwei Maβnahmen vorgeschlagen. Zum einen werden kompensierte Operationsverstärker eingeführt und zum anderen wird der Einfluss von Streukapazitäten bei hohen Frequenzen minimiert indem die Verstärkung mit Kondensatoren kompensiert wird. Durch diese Maβnahmen wird eine Genauigkeit von 0.5% bei niedrigen Frequenzen und 0.9% bei 1 MHz ermöglicht. Mit dem neuen Entwurf der spannungsgesteuerten Stromquelle ist ein entscheidender Meilenstein für die Realisierung tragbarer Messsysteme der Bioimpedanz erreicht. Um eine kurze Messzeit zu realisieren wurde eine vergleichende Studie von Anregungssignalen und deren Signalparameter durchgeführt. Die Ergebnisse zeigen, dass binäre Chirp-Signale aufgrund der reduzierten Messzeit, des niedrigen Crest-Faktors unter 2.8 und hohe Energieeffizienz von mehr als 54% bei hohem Rauschlevel besonders geeignet sind. Simulationsergebnisse zeigen, dass die entwickelte Howland-Stromquelle zusammen mit einem binären Mehrfrequenzsignal den geringsten Amplitudenfehler im gesamten Frequenzbereich realisiert
Books on the topic "Low power excitation source"
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Tajalli, Armin. Extreme low-power mixed signal IC design: Subthreshold source-coupled circuits. New York: Springer, 2010.
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Tajalli, Armin. Extreme low-power mixed signal IC design: Subthreshold source-coupled circuits. New York: Springer, 2010.
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Peixoto, Daniel de Godoy. Ultra-Low-Power IoT Solutions for Sound Source Localization: Combining Mixed-Signal Processing and Machine Learning. [New York, N.Y.?]: [publisher not identified], 2019.
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Tajalli, Armin, and Yusuf Leblebici. Extreme Low-Power Mixed Signal IC Design: Subthreshold Source-Coupled Circuits. Springer New York, 2014.
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Fujishima, Naoto. A high density, low on-resistance, trench lateral power MOSFET with a trench bottom source contact. 2003.
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Rez, Peter. Electrical Power Generation: Renewables—Solar and Wind. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198802297.003.0007.
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Solar and wind power have low power densities. Large areas will be required to generate the electrical energy that we are using right now. These energy sources are intermittent, although sunshine is reasonably predictable in desert climates. Even in these ideal locations, fixed rooftop PV can only be used to meet a relatively small proportion of total electrical demand. Solar thermal with molten salt storage has a higher efficiency, and can better match electrical demands in these places. For wind turbines to generate their advertised or rated power, winds have to be blowing at about 12 m/sec (20 kt or 24 mph). In the United States, except in mountain passes and the Texas panhandle, this does not appear to happen very often. A simple test of whether a given renewable energy source is practical is to check whether it can meet the electrical demands of a single house.
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Martin, Graham R. The Sensory Ecology of Collisions and Entrapment. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199694532.003.0009.
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Collisions of birds with human artefacts (power lines, wind turbines, glass sheets, etc.) are major source of bird mortality. Many birds are also killed by entrapment in fishing nets. A sensory ecology perspective on this problem shows that collision and entrapment occur because these hazards present perceptual tasks that are beyond the capacities of the birds; birds are carrying out tasks where a hazard would not be predicted; or birds perceive the hazard but make an inappropriate categorical response. Birds that fly into power lines and turbines may be simply not looking ahead or are flying in conditions in which their resolution is very low. Reducing collisions requires far more than attempting to make hazards more conspicuous to humans. It requires recognition of the birds’ perceptual limitations and their distraction away from hazard sites. This requires taking account of the particular ecological requirements and sensory capacities of each target species.
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Lansing, Carol. Conflicts Over Gender in Civic Courts. Edited by Judith Bennett and Ruth Karras. Oxford University Press, 2012. http://dx.doi.org/10.1093/oxfordhb/9780199582174.013.005.
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Civic court records are a rare source for medieval social experience and attitudes, including low-status people who do not appear in most records. Because the requirements for proof in Roman law included fama, reputation, and status, witnesses in court discussed and at times differed over which aspects of a person’s behavior determined their honesty and respectability. This could become an implicit debate over gender expectations. Can a concubine be considered an honest woman? The article explores a 1295 case in which a wealthy politician was charged with the rape of a woman who lived as a concubine. The case hinged on the complex medieval legal understandings of rape. It is also a vivid example of a power struggle waged in and out of the court, involving both bribery and judicial torture. Ultimately, it reveals how class and gender expectations for men and women influenced the court process.
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Zhang, Lu. Whose Hard Times? University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252038174.003.0011.
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This chapter carries out an in-depth analysis of the transformation of China's automobile industry and its labor force over the past two decades, with particular attention on how shop-floor, national, and global processes interact in complex ways to produce the specific industrial relations and dynamics of labor unrest in the Chinese automobile industry. It argues that the massive foreign investment in China's auto sector through joint ventures and the increased scale and concentration of automobile production have created and strengthened a new generation of autoworkers with growing workplace bargaining power and grievances. However, the acute contradictory pressures of simultaneously pursuing profitability and maintaining legitimacy with labor have driven large state-owned automakers and Sino-foreign joint ventures to follow a policy of labor force dualism, drawing boundaries between formal and temporary workers. While formal workers enjoy high wages, generous benefits, and relatively secure employment, temporary workers suffer comparatively low wages, unsecure employment, and heavier and dirtier job assignments. Temporary and other low-wage autoworkers have also become the main source of militancy in the auto industry.
Book chapters on the topic "Low power excitation source"
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Ribeiro, M. A., W. B. Lenz, A. M. Tusset, Jose Manoel Balthazar, C. Oliveira, and M. Varanis. "Fractional Dynamics of Harvester with Nonideal Source Excitation." In Nonlinear Vibrations Excited by Limited Power Sources, 357–67. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-96603-4_18.
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Tajalli, Armin, and Yusuf Leblebici. "Subthreshold Source-Coupled Logic." In Extreme Low-Power Mixed Signal IC Design, 61–97. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-6478-6_3.
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Blue, J. E., A. L. Van Buren, and P. A. Semper. "A Low-Frequency, Tow-Powered Sound Source." In Power Transducers for Sonics and Ultrasonics, 178–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76271-0_15.
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Tajalli, Armin, and Yusuf Leblebici. "Subthreshold Source-Coupled Logic Performance Analysis." In Extreme Low-Power Mixed Signal IC Design, 115–39. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-6478-6_5.
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Allen, Thomas J. "High-Power Light Emitting Diodes; An Alternative Excitation Source for Photoacoustic Tomography." In LED-Based Photoacoustic Imaging, 23–43. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3984-8_2.
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Qawasmeh, Ahmad, Abid Malik, Barbara Chapman, Kevin Huck, and Allen Malony. "Open Source Task Profiling by Extending the OpenMP Runtime API." In OpenMP in the Era of Low Power Devices and Accelerators, 186–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-40698-0_14.
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Lühr, Armin, and Alejandro Saenz. "Collisions of low-energy antiprotons with molecular hydrogen: ionization, excitation and stopping power." In EXA/LEAP 2008, 407–12. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02803-8_59.
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Jayakrishnan, Shashvat, Dileep Koodalil, Nived Suresh, and Krishnan Balasubramaniam. "Coded Excitation for Low-Power Operation in Guided Ultrasonic Wave Non-destructive Evaluation." In Lecture Notes in Mechanical Engineering, 307–15. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0186-6_30.
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Nardini, Isabella. "Geothermal Power Generation." In The Palgrave Handbook of International Energy Economics, 183–94. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-86884-0_11.
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AbstractGeothermal energy is emerging as one of the most reliable sources of renewable energy and gaining relevance over conventional and non-renewable sources of energy because of its constant availability and sustainable nature. Furthermore, the deployment of geothermal energy helps reduce a country’s dependence on fossil fuels. Besides being a clean and renewable energy source with a low levelized cost of electricity, geothermal reservoirs have huge potential for power generation and may become the pillar of local grid systems, meeting the baseload demand. However, the active contribution from policy makers is necessary to design and develop economic and financial instruments and a favourable regulatory framework to decrease the risk of investment and the capital cost for private investors.
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Song, Jianzhong, Xiaosong Zhang, Can Yang, and Qikuang Yao. "Analysis of a Combined Power and Heating Thermodynamic System Driven by Low Temperature Heat Source." In Progress in Sustainable Energy Technologies: Generating Renewable Energy, 639–49. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07896-0_40.
Full textConference papers on the topic "Low power excitation source"
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Truitt, Andrew, and S. Nima Mahmoodi. "Piezoelectric Energy Harvesting Through Fluid Excitation." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-8000.
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Piezoelectric energy harvesters have recently captured a lot of attention in research and technology. They employ the piezoelectric effect, which is the separation of charge within a material as a result of an applied strain, to turn what would otherwise be wasted energy into usable energy. This energy can then be used to support remote sensing systems, batteries, and other types of wireless MEMS devices. Such self powered systems are particularly attractive where hardwiring may not be feasible or numerous battery sources unreasonable. The source of excitation for these systems can include direct actuation, natural or mechanical vibrations, or fluid energy (aerodynamic or hydrodynamic). Fluid based energy harvesting is increasingly pursued due to the ubiquitous nature of the excitation source as well as the strong correlation with other types of excitation. Vortex-induced vibrations as well as vibrations induced by bluff bodies have been investigated to determine potential gains. The shape and size of these bluff bodies has been modeled in order to achieve the maxim power potential of the system. Other studies have focused on aeroelastic fluttering which relies on the natural frequency of two structural modes being achieved through aerodynamic forces. Rather than a single degree of freedom, as seen in the VIV approach, aeroelastic flutter requires two degrees of freedom to induce its vibrational state. This has been modeled through a wing section attached to a cantilevered beam via a revolute joint. To accurately model the behavior of these systems several types of dampening must be considered. Fluid flow excitation introduces the component of dampening via fluid dynamics in addition to structural dampening and electrical dampening from the piezoelectrics themselves. Air flow speed modifies the aerodynamic dampening and it has been shown that at the flutterer boundary the aerodynamic dampening dissipates while the oscillations remain. However, such a system state exhibits a decaying power output due to the shunt dampening effect of the power generation itself. Research in energy harvesting is quickly progressing but much has yet to be discovered. The focus of this paper will be fluid as a source of excitation and the development that has followed thus far. Configurations and applications of previous works will be examined followed by suggestions of new research works to move forward in the field.
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Brasil, R. M. L. R. F., F. J. Garzeri, and J. M. Balthazar. "Experimental Validation of a Non-Linear Model Under Non-Ideal Excitation." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48627.
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We present measurements of the non-linear oscillations of a portal frame foundation for a non ideal motor. We consider a three-time redundant structure with two columns, clamped in their bases and a horizontal beam. An electrical unbalanced motor is mounted at mid span of the beam. Two non linear phenomena are studied: a) mode saturation and energy transfer between modes; b) interaction between high amplitude motions of the structure and the rotation regime of a real limited power motor. The dynamic characteristics of the structure were chosen to have one-to-two internal resonance between the antisymmetrical mode (sway motions) and the first symmetrical mode natural frequencies. As the excitation frequency reaches near resonance conditions with the 2nd natural frequency, the amplitude of this mode grows up to a certain level and then it saturates. The surplus energy pumped into the system is transferred to the sway mode, which experiences a sudden increase in its amplitude. Energy is transformed from low amplitude high frequency motion into high amplitude low frequency motion. Such a transformation is potentially dangerous. We consider the fact that real motors, such as the one used in this study, have limited power output. In this case, this energy source is said to be non ideal, in contrast to the ideal source whose amplitude and frequency are independent of the motion of the structure. Our experimental research detected the Sommerfeld Effect: as the motor accelerates to reach near resonant conditions, a considerable part of its output energy is consumed to generate large amplitude motions of the structure and not to increase its own angular speed. For certain parameters of the system, the motor can get stuck at resonance not having enough power to reach higher rotation regimes. If some more power is available, jump phenomena may occur from near resonance to considerably higher motor speed regimes, no stable motions being possible between these two.
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Masana, Ravindra, and Mohammed F. Daqaq. "Exploiting Super-Harmonic Resonances of a Bi-Stable Axially-Loaded Beam for Energy Harvesting Under Low-Frequency Excitations." In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-47723.
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A research paradox currently lies in the design of miniaturized vibratory energy harvesters capable of harnessing energy efficiently from low-frequency excitations. To address this problem, this effort investigates the prospect of utilizing super-harmonic resonances of a bi-stable system to harvest energy from excitation sources with low-frequency components. Towards that objective, the paper considers the electromechanical response of an axially-loaded clamped-clamped piezoelectric beam harvester with bi-stable potential characteristics. By numerically constructing the voltage-frequency bifurcation maps of the response near the super-harmonic resonance of order two, it is shown that, for certain base excitation levels, the harvester can exhibit responses that are favorable for energy harvesting. These include a unique branch of large-orbit periodic inter-well oscillations, coexisting branches of large-orbit solutions, and a bandwidth of frequencies where a unique chaotic attractor exists. In these regions, the harvester can produce power levels that are comparable to those obtained near the primary resonance.
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Adachi, Kazuhiko, and Tatsuya Sakamoto. "Theoretical and Experimental Evaluation of System Energy Balance and Power Generation Efficiency for Piezocomposite Vibration Energy Harvester Under Low Intensity Excitation Condition." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-8157.
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In the authors’ previous study, the vibration energy harvester of the piezoelectric bimorph cantilever type was proposed for vibration condition monitoring applications of industrial rotating machinery. According to an ISO standard, vibration level of newly commissioned class I rotating machinery is under 0.71mm/sec rms in all frequency range. Authors assumed that the typical casing or pedestal vibration amplitude of the rotating machinery was 0.71 mm/sec rms and this low intensity excitation condition was the input for experimental evaluation of the voltage generation performance of the piezocomposit vibration energy harvester. The vibration energy harvester consists of the surface bonded two Macro-Fiber Composites (MFCs). In this study, energy transfer efficiency was derived from the system energy balance during the natural period of the proposed vibration energy harvester. Energy balance equations were successfully obtained from the governing equations of the piezoelectrically coupled electromechanical system. The maximum AC power through 114.3 Kilo-Ohm resistor which includes instrument internal resistances experimentally obtained 242.07 microwatt when subjected to vibration source input magnitude of 0.71 mm/s rms at the resonant frequency of the harvester (29.42 Hz). The impedance matching between MFCs and the electrical resistive load was effective for maximizing AC power transfer of the vibration energy harvester. Estimated energy transfer from mechanical system to electrical system shows the agreement with the experimentally evaluated generating power during the natural period of the vibration energy harvester with about 3% difference. Estimated energy transfer efficiency was about 30% for different excitation magnitudes: 0.71, 0.568 and 0.355 mm/sec rms.
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Richards, Simon K., Kishore Ramakrishnan, Chingwei M. Shieh, Franc¸ois Moyroud, Alain Picavet, Valeria Ballarini, and Vittorio Michelassi. "Unsteady Acoustic Forcing on an Impeller Due to Coupled Blade Row Interactions." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23771.
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This article contains an investigation of the unsteady acoustic forcing on a centrifugal impeller due to coupled blade row interactions. Selected results from an aeromechanical test campaign on a GE Oil and Gas centrifugal compressor stage with a vaneless diffuser are presented. The most commonly encountered sources of impeller excitation due to upstream wake interaction were identified and observed in the testing campaign. A 30/rev excitation corresponding to the sum of upstream and downstream vane counts caused significant trailing edge vibratory stress amplitudes. Due to the large spacing between the impeller and the return channel vanes, this 30/rev excitation was suspected to be caused by an aero-acoustic excitation rather than a potential disturbance. The origin of this aero-acoustic excitation was deduced from an acoustic analysis of the unsteady compressor flow derived from CFD. The analysis revealed a complex excitation mechanism caused by impeller interaction with the upstream vane row wakes and subsequent acoustic wave reflection from the downstream return channel vanes. The findings show it is important to account for aero-acoustic forcing in the aeromechanical design of low pressure ratio centrifugal compressor stages.
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C. Linhares, Cassiano, João S. Costa, Ricardo E. R. Teixeira, Cristiano P. Coutinho, Sérgio M. O. Tavares, João P. A. E. Santo, and Hélder F. G. Mendes. "Influence of Active Part Stiffness on Radiated Sound Power Level in Power Transformers." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11513.
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Abstract Power transformers are associated with the radiation of unwanted noise in many circumstances due to its low frequency and relative high power, which reduction and mitigation is imperative. It is known that the main source of this noise are originated by the vibrations induced in the active part, namely the core, primarily due to electromagnetic forces and magnetomechanical effects. On the other hand, the laminated design of the core is indispensable in order to reduce the Foucault currents losses. Thus, in addition to the electrical requirements, the development of an appropriate model of the core dynamic behavior taking into account its segmented structure is urgent, in order to avoid resonances at any of the excitation frequencies. In the current proceeding, the influence of the core equivalent dynamic mechanical properties on a power transformer radiated noise was studied by performing a numerical parametric analysis. It was concluded that the active part stiffness properties, namely the directional component related to the out of lamination plane bending, ruled the vibroacoustic behavior of the transformer for the studied frequency range.
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Hendrickson, Brian S., and Stuart B. Brown. "Motion Energy Harvesting Using Catch-and-Release Mechanism." In ASME 2008 2nd International Conference on Energy Sustainability collocated with the Heat Transfer, Fluids Engineering, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/es2008-54191.
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Small-scale motion energy harvesting has garnered significant interest in recent years, especially given advances in piezoelectric materials, but with limited commercial application. Most harvesting methods to date, including those employing magnetic induction, have focused on coupled resonance. Such harvesters are tuned to resonate with their excitation source and have shown promise in capturing moderately high-frequency (>10Hz), low-displacement motion that is steady. However, coupled harvesters lose efficiency significantly when a source deviates slightly in frequency. They also require large masses and/or buoyant volumes to efficiently capture low frequency (<10Hz) motion. We have been developing a novel technology that combines electromagnetic induction with a proprietary catch-and-release mechanism that absorbs an input motion and then releases it at a much higher frequency to improve conversion efficiency. The energy harvester is simple, compact, and insensitive to excitation frequency. Initial prototypes have demonstrated power densities and specific powers many multiples greater than the best-performing, commercial vibration harvester. We have also developed a validated computer model of the system that indicates that performance could be improved 2–4 times over initial prototypes.
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Bake, Friedrich, Ulf Michel, and Ingo Roehle. "Investigation of Entropy Noise in Aero-Engine Combustors." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90093.
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Strong evidence is presented that entropy noise is the major source of external noise in aero-engine combustion. Entropy noise is generated in the outlet nozzles of combustors. Low frequency entropy noise — which was predicted earlier in theory and numerical simulations — was successfully detected in a generic aero-engine combustion chamber. It is shown that entropy noise dominates even in the case of thermo-acoustic resonances. In addition to this, a different noise generating mechanism was discovered that is presumably of even higher relevance to jet engines: There is strong evidence of broad band entropy noise at higher frequencies (1 kHz to 3 kHz in the reported tests). This unexpected effect can be explained by the interaction of small scale entropy perturbations (hot spots) with the strong pressure gradient in the outlet nozzle. The direct combustion noise of the flame zone seems to be of minor importance for the noise emission to the ambiance. The combustion experiments were supplemented by experiments with electrical heating. Two different methods for generating entropy waves were used, a pulse excitation and a sinusoidal excitation. In addition, high-frequency entropy noise was generated by steady electrical heating.
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Wang, Jun, Scott Chang, Chin An Tan, and Greg Auner. "A Novel Structure for Cantilever-Beam MEMS Power Generator." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-35857.
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A novel cantilever-beam type MEMS power generator is proposed for the conversion of vibration mechanical energy to electrical energy through piezoelectric effects. In the various MEMS-based micro power generating schemes, piezoelectric conversion usually achieves a higher efficiency than that of electromagnetic or electrostatic schemes. Currently, most cantilever-beam type MEMS power generators are suitable for harvesting energy in relatively high frequency ranges (500 Hz to 14 kHz), but are not effective in harvesting low frequency (<10 Hz) vibration energy, such as energy from human walking or ocean wave, for which MEMS power generators are most desired. In this paper, a new cantilever-beam MEMS power generator is proposed, which can greatly improve the power conversion for low frequency circumstances. The power generator consists of two sets of cantilever beams: 1. A properly designed mm-size cantilever-beam with metal as the proof mass, and having low resonant frequency matching that of the external low frequency excitation sources. This is to be used to effectively couple the external motion. 2. An array of micro thin film piezoelectric (PZT) cantilever-beams, each with metal as proof mass, and having higher resonant frequencies. The external excitation is coupled to the single cantilever beam with kinetic energy. Through impact between the mm-size cantilever beam (low frequency) and the micro cantilever beam array (high frequency), the coupled mechanical energy is transferred to electrical energy through piezoelectric effect. Simulation results show that energy conversion efficiency can be greatly improved by using such a coupled structure as compared to that of only using MEMS cantilever beams with high frequency or a single mm-size beam structure. This may have a wide range of applications in pervasive computing and biomedical engineering.
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Wang, Fengxia, Wei Wu, Andy Lozowski, Vahid Alizadehyazdi, and Amin Abedini. "Energy Harvesting With a Piezoelectric THUNDER." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50606.
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In this work the energy harvesting performance of a piezoelectric curved energy generator (THUNDER) is studied via experimental and analytical methods. The analytical model of the THUNDER is created based on the linear mechanical electrical constitutive law of the piezoelectric material, the linear elastic constitutive law of the substrate, and the Euler-Bernoulli beam theory. With these linear modal functions, the Rayleigh-Ritz approach was used to then obtain the reduced mechanical electrical coupled modulation equations. With above analytical model two types of energy harvest circuit are proposed and compared: 1) directly charging mode at low level excitation, and 2) memory stored optimal duty cycle step-down converter mode at high level excitation. The value of the optimal duty cycle is determined based on the characteristics of the vibration signals of the ambient vibration source. To reduce the energy consumption of the microcontroller, the optimum duty cycle values are stored in the microprocessor instead of doing onsite computing during energy harvesting process. For the purpose of designing a low power cost mechanical switch to control the operation of both modes, the threshold voltage between these two operation modes is converted into threshold displacement.
Reports on the topic "Low power excitation source"
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Harry L. Tuller. Photo-Activated Low Temperature, Micro Fuel Cell Power Source. Office of Scientific and Technical Information (OSTI), March 2007. http://dx.doi.org/10.2172/924770.
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Kim, Sung H. Germanium-Source Tunnel Field Effect Transistors for Ultra-Low Power Digital Logic. Fort Belvoir, VA: Defense Technical Information Center, May 2012. http://dx.doi.org/10.21236/ada561720.
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Hui, J., D. Culler, and V. Manral. An IPv6 Routing Header for Source Routes with the Routing Protocol for Low-Power and Lossy Networks (RPL). RFC Editor, March 2012. http://dx.doi.org/10.17487/rfc6554.
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Jay. L51723 Guidelines for Sound Power Level Measurements Compressor Equipment. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 1994. http://dx.doi.org/10.55274/r0010419.
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Increasing legislation and public awareness of noise are intensifying the efforts of industries today to reduce the noise. The natural gas industry has proved that it is one of the industrial leaders in its awareness of noise problems and has maintained a vigorous research program in noise control for over 30 years. A noise survey can be done in several ways: point measurements, grid point methods, contour methods, scanning techniques, etc. The selection of the method depends on the accuracy required, available personnel, expertise etc. For the most accurate determination of sound power, the scanning method using sound intensity measurements is considered to be the best available in present day circumstances. This method is discussed in detail in later chapters. Point and grid point measurements are useful to determine the Sound Pressure Level, but are of limited use in quantifying the Sound Power Level of a noise source in a complex and multi-source environment such as a compressor station. Guidelines for Sound Power Level Measurements for Compressor Station Equipment Report documents the development of guidelines for in-situ sound power level measurements for compressor station equipment, with sample calculations. Measurement of equipment noise levels in a complex, multi-source environment is very difficult and may be accomplished by several methods. These guidelines specify the sound intensity approach that can be used in almost any field situation. The sound power guidelines described in this report specify the sound intensity approach as the primary measurement method since it can be used in almost any field situation to determine the sound power of a source. In open spaces without reflecting surfaces (except the ground plane) sound pressure measurements may give satisfactory estimates of the sound power of noise sources if background noise is low and other sources can be turned off. Inside a compressor building, the modified reverberation room approach may be allowed, but then only the total sound power can be determined unless background sources can be controlled or other sources turned off. Lastly, the standard guidelines developed were used to conduct field measurements of the sound power of four equipment noise sources including: a) turbine casing, b) turbine air inlet, c) cooler and d) exhaust stack.
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Kiefner, Maxey, and Eiber. L51607 Pipeline Coating Impedance Effect on Powerline Fault Current Coupling. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 1989. http://dx.doi.org/10.55274/r0010294.
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Prior research leading to the development of predictive electromagnetic coupling computer codes has shown that the coating conductance is the principal factor in determining the response of a pipeline to magnetic induction transmission line. Under power line fault conditions, a high voltage may stress the coating causing a significant change in its conductance, and hence, the coupling response. Based upon laboratory experimentation and analysis, a model has been developed which allows prediction of the modified coating characteristics when subjected to high voltages during fault situations. The program objective was the investigation of a method to determine the high voltage behavior of an existing coating from low voltage in-situ field measurements. Such a method appeared conceptually feasible for non-porous coatings whose conductance is primarily a result of current leakage through existing holidays. However, limited testing has shown that difficulties in determining the steel-electrolyte capacitance limit the application of the method. Methods for field measurement of the pipeline coating conductance were studied for both DC and AC signal excitation. AC techniques offer the advantage that cathodic protection current interruption is not required, thus eliminating depolarization effects. However, ac field measurement techniques need additional refinement before these methods can be generally applied.
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Riter, Karmann, Anthony Clint Clayton, Kelley Rountree, and Prakash Doraiswamy. Solar Station for an Off-the-Grid Air Quality Sensor System. RTI Press, June 2023. http://dx.doi.org/10.3768/rtipress.2023.mr.0051.2306.
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Air quality monitoring is a rapidly growing area of citizen science, or community science (CS), thanks to the availability of low-cost sensors. Contributing to a crowdsourced data platform (e.g., http:// purpleair .com/ map) is usually easy in urban areas, where there is access to uninterrupted electricity and wireless internet (Wi-Fi). However, there are sometimes security restrictions on Wi-Fi or a lack of exterior power outlets. Also, rural regions, particularly in low- and middle-income countries, often lack electricity and Wi-Fi continuity. RTI International has designed and distributed a solar power and Wi-Fi station that can adequately power both a small air quality sensor (e.g., PurpleAir PA-II) and a Wi-Fi hotspot to overcome these challenges. The station housing can accommodate a battery, a controller, and a cell phone or another type of Wi-Fi hotspot device. This paper discusses the need for such a station; a design for the current station, including parts list; suggestions for modifications in various use cases; and design factors to consider, including amount of sunlight per day, intended number of operational days under cloudy conditions, season, and total power requirements. This method is intended to be open source and a starting point for citizen scientists and CS projects.
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MacDonald, James D., Aharon Abeliovich, Manuel C. Lagunas-Solar, David Faiman, and John Kabshima. Treatment of Irrigation Effluent Water to Reduce Nitrogenous Contaminants and Plant Pathogens. United States Department of Agriculture, July 1993. http://dx.doi.org/10.32747/1993.7568092.bard.
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The contamination of surface and subterranean drinking water supplies with nitrogen-laden agricultural wastewater is a problem of increasing concern in the U.S. and Israel. Through this research, we found that bacteria could utilize common organic wastes (e.g. paper, straw, cotton) as carbon sources under anaerobic conditions, and reduce nitrate concentrations in wastewater to safe levels. Two species of bacteria, Cellulomonas uda and a Comamonas sp., were required for dentitrification. Celulomonas uda degraded cellulose and reduced nitrate to nitrite. In addition, it excreted soluble organic carbon needed as a food source by the Comamonas sp. for completion of denitrification. We also found that recirculated irrigation water contains substantial amounts of fungal inoculum, and that irrigating healthy plants with such water leads to significant levels of root infection. Water can be disinfected with UV, but our experiments showed that Hg-vapor lamps do not possess sufficient energy to kill spores in wastewater containing dissolved organics. Excimer lasers and Xenon flashlamps do possess the needed power levels, but only the laser had a high enough repetition rate to reliably treat large volumes of water. Ozone was highly efficacious, but it's use as a water treatment is probably best suited to moderate or low volume irrigation systems. This research provides critical data needed for the design of effective water denitrification and/or pathogen disinfection systems for different growing operations.
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VIBRO-ACOUSTICAL PERFORMANCE OF A STEEL BEAM OF GROOVE PROFILE: FIELD TEST AND NUMERICAL ANALYSIS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.063.
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To meet the development needs of rail transit, steel beams are more widely used in bridges, which brings more significant vibration and noise problems. In this paper, the dynamic characteristics of a steel beam of groove profile are investigated through field test and numerical analysis. Firstly, under the hammering excitation, the vibration response of the slabs in a descending order are right web, left web and bottom slab. The vibration response is related to the distance from the response position to the excitation source and the stiffness of slabs. Then, a numerical model of the steel beam is established based on the hybrid FE-SEA method. The results of field test are consistent with the numerical simulation, which confirms the effectiveness of the hybrid FE-SEA method when analyzing the steel beam. Finally, by comparing the sound power level radiated from different slabs in three zones, it can be concluded that the sound power level is related to the distance from the test position to the excitation source. The overall sound power level will increase when canceling transverse connection system, and center excitation has a more significant effect than off-center excitation.
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Vehicle Surge Reduction Technology during Towing in Parallel HEV Pickup Truck. SAE International, March 2022. http://dx.doi.org/10.4271/2022-01-0613.
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This paper proposes a technology to reduce vehicle surge during towing that utilizes motors and shifting to help ensure comfort in a parallel HEV pickup truck. Hybridization is one way to reduce fuel consumption and help realize carbon neutrality. Parallel HEVs have advantages in the towing, hauling, and high-load operations often carried out by pickup trucks, compared to other HEV systems. Since the engine, motor, torque converter, and transmission are connected in series in a parallel HEV, vehicle surge may occur when the lockup clutch is engaged to enhance fuel efficiency, similar to conventional powertrains. Vehicle surge is a low-frequency vibration phenomenon. In general, the source is torque fluctuation caused by the engine and tires, with amplification provided by first-order torsional driveline resonance, power plant resonance, suspension resonance, and cabin resonance. This vibration is amplified more during towing. Therefore, this paper proposes two surge reduction technologies to help achieve fuel efficiency and surge at the same time during towing. One technology is a gear shift control that avoids engine operating zones where two or more resonance frequencies coincide, which is realized by changing the equivalent inertia via appropriate gear selection. The second technology is an anti-vibration control, which makes effective use of the hybrid system motors by adding motor torque to suppress the relative displacement between the driveline and the tires.
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Multiple Engine Faults Detection Using Variational Mode Decomposition and GA-K-means. SAE International, March 2022. http://dx.doi.org/10.4271/2022-01-0616.
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As a critical power source, the diesel engine is widely used in various situations. Diesel engine failure may lead to serious property losses and even accidents. Fault detection can improve the safety of diesel engines and reduce economic loss. Surface vibration signal is often used in non-disassembly fault diagnosis because of its convenient measurement and stability. This paper proposed a novel method for engine fault detection based on vibration signals using variational mode decomposition (VMD), K-means, and genetic algorithm. The mode number of VMD dramatically affects the accuracy of extracting signal components. Therefore, a method based on spectral energy distribution is proposed to determine the parameter, and the quadratic penalty term is optimized according to SNR. The results show that the optimized VMD can adaptively extract the vibration signal components of the diesel engine. In the actual fault diagnosis case, it is difficult to obtain the data with labels. The clustering algorithm can complete the classification without labeled data, but it is limited by the low accuracy. In this paper, the optimized VMD is used to decompose and standardize the vibration signal. Then the correlation-based feature selection method is implemented to obtain the feature results after dimensionality reduction. Finally, the results are input into the classifier combined by K-means and genetic algorithm (GA). By introducing and optimizing the genetic algorithm, the number of classes can be selected automatically, and the accuracy is significantly improved. This method can carry out adaptive multiple fault detection of a diesel engine without labeled data. Compared with many supervised learning algorithms, the proposed method also has high accuracy.