51,138 research outputs found
Electronic integration of the uk-1 international ionosphere satellite
Electronic integration of international ionosphere satellit
Vanadium redox flow batteries: Potentials and challenges of an emerging storage technology
open4noIn this paper an overview of Vanadium Redox Flow Battery technologies, architectures, applications and power electronic interfaces is given. These systems show promising features for energy storage in smart grid applications, where the intermittent power produced by renewable sources must meet strict load requests and economical opportunities. This paper reviews the vanadium-based technology for redox flow batteries and highlights its strengths and weaknesses, outlining the research lines that aim at taking it to full commercial success.openSpagnuolo, Giovanni, Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni;Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni; Spagnuolo, Giovann
Photovoltaic sample-and-hold circuit enabling MPPT indoors for low-power systems
Photovoltaic (PV) energy harvesting is commonly used to power autonomous devices, and maximum power point tracking (MPPT) is often used to optimize its efficiency. This paper describes an ultra low-power MPPT circuit with a novel sample-and-hold and cold-start arrangement, enabling MPPT across the range of light intensities found indoors, which has not been reported before. The circuit has been validated in practice and found to cold-start and operate from 100 lux (typical of dim indoor lighting) up to 5000 lux with a 55cm2 amorphous silicon PV module. It is more efficient than non-MPPT circuits, which are the state-of-the-art for indoor PV systems. The proposed circuit maximizes the active time of the PV module by carrying out samples only once per minute. The MPPT control arrangement draws a quiescent current draw of only 8uA, and does not require an additional light sensor as has been required by previously-reported low-power MPPT circuits
Embedding Principal Component Analysis for Data Reductionin Structural Health Monitoring on Low-Cost IoT Gateways
Principal component analysis (PCA) is a powerful data reductionmethod for
Structural Health Monitoring. However, its computa-tional cost and data memory
footprint pose a significant challengewhen PCA has to run on limited capability
embedded platformsin low-cost IoT gateways. This paper presents a
memory-efficientparallel implementation of the streaming History PCA
algorithm.On our dataset, it achieves 10x compression factor and 59x
memoryreduction with less than 0.15 dB degradation in the
reconstructedsignal-to-noise ratio (RSNR) compared to standard PCA. More-over,
the algorithm benefits from parallelization on multiple cores,achieving a
maximum speedup of 4.8x on Samsung ARTIK 710
A sub-mW IoT-endnode for always-on visual monitoring and smart triggering
This work presents a fully-programmable Internet of Things (IoT) visual
sensing node that targets sub-mW power consumption in always-on monitoring
scenarios. The system features a spatial-contrast binary
pixel imager with focal-plane processing. The sensor, when working at its
lowest power mode ( at 10 fps), provides as output the number of
changed pixels. Based on this information, a dedicated camera interface,
implemented on a low-power FPGA, wakes up an ultra-low-power parallel
processing unit to extract context-aware visual information. We evaluate the
smart sensor on three always-on visual triggering application scenarios.
Triggering accuracy comparable to RGB image sensors is achieved at nominal
lighting conditions, while consuming an average power between and
, depending on context activity. The digital sub-system is extremely
flexible, thanks to a fully-programmable digital signal processing engine, but
still achieves 19x lower power consumption compared to MCU-based cameras with
significantly lower on-board computing capabilities.Comment: 11 pages, 9 figures, submitteted to IEEE IoT Journa
The Importance of Monitoring Renewable Energy Plants: Three Case Histories
Many renewable energy plants are put into operation without providing a monitoring
system to evaluate their performance over time. Then if is often difficult to realise the bad working of
the system and the loss of efficiency results in an economic loss. In the Author\u2019s experience as
designer or supervisor of such plants, he came across various examples that pointed out the
advantages of having installed a monitoring system, of course with a careful data analysis. Problems
sometimes arose from poorer performance than anticipated in the design, but more often from
inefficient plant operations after some months or years from the starting.
Three quite different examples, derived from the Author\u2019s direct experience, are reported to
illustrate how real performance can be lower than designed due respectively:
1. To bad settings of the parameters;
2. To a hurried commissioning that did not reveal the mistakes in the design of the plant;
3. To a failure of a single component over time
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