scholarly journals An Experimental Strategy for Characterizing Inductive Electromagnetic Energy Harvesters

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 647
Author(s):  
Pedro Martín Sánchez ◽  
Fco. Javier Rodríguez Sánchez ◽  
Enrique Santiso Gómez
Keyword(s):  
High Voltage ◽  
Energy Harvester ◽  
Optimal Solution ◽  
Distribution Networks ◽  
Magnetic Core ◽  
Electromagnetic Energy ◽  
Power Conditioning ◽  
Case Scenario ◽  
Worst Case ◽  
Voltage Range

Condition monitoring of high voltage power lines through self-powered sensor systems has become a priority for utilities with the aim of detecting potential problems, enhancing reliability of the power transmission and distribution networks and mitigating the adverse impact of faults. Energy harvesting from the magnetic field generated by the alternating current flowing through high voltage lines can supply the monitoring systems with the required power to operate without relying on hard-wiring or battery-based approaches. However, developing an energy harvester, which scavenges the power from such a limited source of energy, requires detailed design considerations, which may not result in a technically and economically optimal solution. This paper presents an innovative simulation-based strategy to characterize an inductive electromagnetic energy harvester and the power conditioning system. Performance requirements in terms of the harvested power and output voltage range, or level of magnetic core saturation can be imposed. Different harvester configurations, which satisfy the requirements, have been produced by the simulation models. The accuracy and efficiency of this approach is verified with an experimental setup based on an energy harvester, which consists of a Si-steel magnetic core and a power conditioning unit. For the worst-case scenario with a primary current of 5 A, the maximum power extracted by the harvester can be as close as 165 mW, resulting in a power density of 2.79 mW/cm3.

scholarly journals Secrecy Wireless-Powered Sensor Networks for Internet of Things

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Junxia Li ◽  
Hui Zhao ◽  
Xueyan Chen ◽  
Zheng Chu ◽  
Li Zhen ◽  
...  
Keyword(s):  
Time Allocation ◽  
Optimization Problem ◽  
Optimal Solution ◽  
Access Point ◽  
Case Scenario ◽  
Secrecy Rate ◽  
Global Optimal Solution ◽  
Worst Case ◽  
Sdp Relaxation ◽  
Global Optimal

This paper investigates a secure wireless-powered sensor network (WPSN) with the aid of a cooperative jammer (CJ). A power station (PS) wirelessly charges for a user equipment (UE) and the CJ to securely transmit information to an access point (AP) in the presence of multiple eavesdroppers. Also, the CJ are deployed, which can introduce more interference to degrade the performance of the malicious eavesdroppers. In order to improve the secure performance, we formulate an optimization problem for maximizing the secrecy rate at the AP to jointly design the secure beamformer and the energy time allocation. Since the formulated problem is not convex, we first propose a global optimal solution which employs the semidefinite programming (SDP) relaxation. Also, the tightness of the SDP relaxed solution is evaluated. In addition, we investigate a worst-case scenario, where the energy time allocation is achieved in a closed form. Finally, numerical results are presented to confirm effectiveness of the proposed scheme in comparison to the benchmark scheme.

scholarly journals Fast Solver for Implicit Continuous Set Model Predictive Control of Electric Drives

2021 ◽  
Author(s):  
Riccardo Torchio ◽  
Andrea Favato ◽  
Paolo Gherardo Carlet ◽  
Francesco Toso ◽  
Ruggero Carli ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Real Time ◽  
Predictive Control ◽  
A Priori ◽  
Optimal Solution ◽  
Experimental Tests ◽  
Current Control ◽  
Computational Time ◽  
Case Scenario ◽  
Worst Case

<div>This paper proposes an effective solver for implicit Continuous Set Model Predictive Control for the current control loop of synchronous motor drives with input constraints, allowing for reaching the maximum voltage feasible set. The related quadratic programming problem requires an iterative solver to find the optimal solution. The real-time certification of the algorithm is of paramount importance to move the technology toward industrial-scale applications by the proposed solver. The total number of operations can be computed in the worst-case scenario, thus the maximum computational time is known a priori. The solver is deeply illustrated, showing its feasibility for real-time applications in the microseconds range by means of experimental tests. Promising results are obtained with respect to well known general purpose solvers.</div>

scholarly journals How and when to end the COVID-19 lockdown: an optimisation approach

2020 ◽  
Author(s):  
Thomas Rawson ◽  
Tom Brewer ◽  
Dessislava Veltcheva ◽  
Chris Huntingford ◽  
Michael B. Bonsall
Keyword(s):  
Transmission Rate ◽  
Optimal Solution ◽  
Case Scenario ◽  
Model Framework ◽  
Accurate Identification ◽  
Worst Case ◽  
Seir Model ◽  
Infected People ◽  
Worst Case Scenario ◽  
Gradual Release

Countries around the world are in a state of lockdown to help limit the spread of SARS-CoV-2. However, as the number of new daily confirmed cases begins to decrease, governments must decide how to release their populations from quarantine as efficiently as possible without overwhelming their health services. We applied an optimal control framework to an adapted Susceptible-Exposure-Infection-Recovery (SEIR) model framework to investigate the efficacy of two potential lockdown release strategies, focusing on the UK population as a test case. To limit recurrent spread, we find that ending quarantine for the entire population simultaneously is a high-risk strategy, and that a gradual re-integration approach would be more reliable. Furthermore, to increase the number of people that can be first released, lockdown should not be ended until the number of new daily confirmed cases reaches a sufficiently low threshold. We model a gradual release strategy by allowing different fractions of those in lockdown to re-enter the working non-quarantined population. Mathematical optimisation methods, combined with our adapted SEIR model, determine how to maximise those working while preventing the health service from being overwhelmed. The optimal strategy is broadly found to be to release approximately half the population two-to-four weeks from the end of an initial infection peak, then wait another three-to-four months to allow for a second peak before releasing everyone else. We also modelled an ''on-off'' strategy, of releasing everyone, but re-establishing lockdown if infections become too high. We conclude that the worst-case scenario of a gradual release is more manageable than the worst-case scenario of an on-off strategy, and caution against lockdown-release strategies based on a threshold-dependent on-off mechanism. The two quantities most critical in determining the optimal solution are transmission rate and the recovery rate, where the latter is defined as the fraction of infected people in any given day that then become classed as recovered. We suggest that the accurate identification of these values is of particular importance to the ongoing monitoring of the pandemic.

Significance of bacteria associated with invertebrates in drinking water distribution networks

2005 ◽  
Vol 52 (8) ◽  
pp. 171-175 ◽  
Author(s):  
E. Wolmarans ◽  
H.H. du Preez ◽  
C.M.E. de Wet ◽  
S.N. Venter
Keyword(s):  
Drinking Water ◽  
Water Distribution ◽  
Drinking Water Treatment ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Case Scenario ◽  
Worst Case ◽  
Potential Health ◽  
Water Users ◽  
Drinking Water Distribution

The implication of invertebrates found in drinking water distribution networks to public health is of concern to water utilities. Previous studies have shown that the bacteria associated with the invertebrates could be potentially pathogenic to humans. This study investigated the level and identity of bacteria commonly associated with invertebrates collected from the drinking water treatment systems as well as from the main pipelines leaving the treatment works. On all sampling occasions bacteria were isolated from the invertebrate samples collected. The highest bacterial counts were observed for the samples taken before filtration as was expected. There were, however, indications that optimal removal of invertebrates from water did not always occur. During the investigation, 116 colonies were sampled for further identification. The isolates represent several bacterial genera and species that are pathogenic or opportunistic pathogens of humans. Diarrhoea, meningitis, septicaemia and skin infections are among the diseases associated with these organisms. The estimated number of bacteria that could be associated with a single invertebrate (as based on average invertebrate numbers) could range from 10 to 4000 bacteria per organism. It can, therefore, be concluded that bacteria associated with invertebrates might under the worst case scenario pose a potential health risk to water users. In the light of the above findings it is clear that invertebrates in drinking water should be controlled at levels as low as technically and economically feasible.

scholarly journals Fast Solver for Implicit Continuous Set Model Predictive Control of Electric Drives

2021 ◽  
Author(s):  
Andrea Favato ◽  
Paolo Gherardo Carlet ◽  
Francesco Toso ◽  
Riccardo Torchio ◽  
Ludovico Ortombina ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Real Time ◽  
Predictive Control ◽  
Optimal Solution ◽  
Computation Time ◽  
Experimental Tests ◽  
Current Control ◽  
Computational Time ◽  
Case Scenario ◽  
Worst Case

<div>This paper proposes a fast and accurate solver for implicit Continuous Set Model Predictive Control for the current control loop of synchronous motor drives with input constraints, allowing for reaching the maximum voltage feasible set. The related control problem requires an iterative solver to find the optimal solution. The real-time certification of the algorithm is of paramount importance to move the technology toward industrial-scale applications.</div><div>A relevant feature of the proposed solver is that the total number of operations can be computed in the worst-case scenario. Thus, the maximum computational time is known a priori. The solver is deeply illustrated, showing its feasibility for real-time applications in the microseconds range by means of experimental tests.</div><div>The proposed method outperforms general-purpose algorithms in terms of computation time, while keeping the same accuracy.</div>

scholarly journals Fast Solver for Implicit Continuous Set Model Predictive Control of Electric Drives

2021 ◽  
Author(s):  
Riccardo Torchio ◽  
Andrea Favato ◽  
Paolo Gherardo Carlet ◽  
Francesco Toso ◽  
Ruggero Carli ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Real Time ◽  
Predictive Control ◽  
A Priori ◽  
Optimal Solution ◽  
Experimental Tests ◽  
Current Control ◽  
Computational Time ◽  
Case Scenario ◽  
Worst Case

<div>This paper proposes an effective solver for implicit Continuous Set Model Predictive Control for the current control loop of synchronous motor drives with input constraints, allowing for reaching the maximum voltage feasible set. The related quadratic programming problem requires an iterative solver to find the optimal solution. The real-time certification of the algorithm is of paramount importance to move the technology toward industrial-scale applications by the proposed solver. The total number of operations can be computed in the worst-case scenario, thus the maximum computational time is known a priori. The solver is deeply illustrated, showing its feasibility for real-time applications in the microseconds range by means of experimental tests. Promising results are obtained with respect to well known general purpose solvers.</div>

Analysis of photographic emulsions for High-Voltage Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 452-453 ◽  
Author(s):  
James R. Kremer ◽  
Paul S. Furcinitti ◽  
Eileen O’Toole ◽  
J. Richard McIntosh
Keyword(s):  
Electron Microscope ◽  
Optical Density ◽  
High Voltage ◽  
Noise Power ◽  
Limited Information ◽  
Modulation Transfer ◽  
Transmission Microscopy ◽  
High Voltage Electron Microscopy ◽  
Voltage Range ◽  
Voltage Electron

Characteristics of electron microscope film emulsions, such as the speed, the modulation transfer function, and the exposure dependence of the noise power spectrum, have been studied for electron energies (80-100keV) used in conventional transmission microscopy. However, limited information is available for electron energies in the intermediate to high voltage range, 300-1000keV. Furthermore, emulsion characteristics, such as optical density versus exposure, for new or improved emulsions are usually only quoted by film manufacturers for 80keV electrons. The need for further film emulsion studies at higher voltages becomes apparent when searching for a film to record low dose images of radiation sensitive biological specimens in the frozen hydrated state. Here, we report the optical density, speed and relative resolution of a few of the more popular electron microscope films after exposure to 1MeV electrons.Three electron microscope films, Kodak S0-163, Kodak 4489, and Agfa Scientia 23D56 were tested with a JEOLJEM-1000 electron microscope operating at an accelerating voltage of 1000keV.

Reducing Probabilistic Weather Forecasts to the Worst Case Scenario: Anchoring Effects

2008 ◽  
Author(s):  
Sonia Savelli ◽  
Susan Joslyn ◽  
Limor Nadav-Greenberg ◽  
Queena Chen
Keyword(s):  
Case Scenario ◽  
Worst Case ◽  
Weather Forecasts ◽  
Worst Case Scenario ◽  
Anchoring Effects
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