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- 2018
- spectral irradiance
- correlated color temperature
- double monochromator
- color rendering index
- Uncertainty of measurement
- Measurement and Control Technology and Instruments
- Brno University of Technology
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[IEEE 2019 4th World Conference on Complex Systems (WCCS) - Ouarzazate, Morocco (2019.4.22-2019.4.25)] 2019 4th World Conference on Complex Systems (WCCS) - Adaptive High Gain Observer for Photovoltaic Systems
摘要： The problem of state and parameter estimation in photovoltaic (PV) systems is considered. The system is composed of a photovoltaic generator (PVG) which supplies power, via a long PV cable, to a DC centrifugal pump driven by a DC–DC boost converter. The maximum power point tracking (MPPT) techniques and controllers are generally designed based on the PVG delivered voltage and/or current measurements. From other side, PV arrays should be established in a location that pro?ts from good daily solar radiation. Such a location is, in numerous cases, remote from the converter, which obviously leads to dif?culty of PVG voltage and current measurement. Besides, the use of a long PV cable may result in MPPT control inaccuracies due to voltage drops in the cable. For remedying these issues, an adaptive observer for PV systems is proposed, in this work. It accomplishes online estimation of PVG current and voltage as well as of the unknown resistance parameter of the cable. The designed adaptive observer convergence is theoretically proved and its performances are evaluated by simulation.
关键词： PV Cable,Uncertainty,Adaptive High Gain Observer,Photovoltaic,MPPT,Lyapunov Stability
更新于2025-09-12 10:27:22
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Revisiting the calculation of performance margins in monitoring-enabled optical networks
摘要： In the context of future intelligent optical networks, dedicated learning techniques can be employed to monitor physical system parameters with a guaranteed accuracy. In this work, we investigate a method that establishes the link between input parameter uncertainties and the overall performance uncertainty. To this end, neglecting stochastic effects and focusing on the input parameters of a simplified Gaussian noise model version, we employ uncertainty propagation to evaluate the overall performance uncertainty from input parameter uncertainties, and we propose a simple way to link performance uncertainty to margins. With this method, as opposed to direct performance monitoring, it is possible to trace, in a predictable way, the path from the cause (input parameter uncertainties) to the effect (performance uncertainty) and to the additional network-level consequences (performance margins). We briefly review methods used in the literature to set margins in classical systems, and we show how all methods can be unified by means of the correlation between input parameters. By quantifying the impact of input parameter correlations, we further discuss the margins that can be saved if input parameters are partially correlated or uncorrelated, compared to a scenario in which parameters are fully correlated. We finally illustrate the separate impact of each parameter on performance uncertainty, and we briefly discuss their order of importance as a function of the system operating regime and propagated distance.
关键词： optical networks,performance margins,deterministic margins,uncertainty propagation,Gaussian noise model
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Measurement of Molecular Transition Frequencies with the Uncertainties Lower Than 10 <sup>?17</sup>
摘要： Precise measurement of atomic transition frequencies (neutral, ion) have been performed and the uncertainty of the order of 10-18 has been attained with several transitions. However, the measurement uncertainty lower than 10-15 has never been attained with molecular transition frequencies. Precise measurement of molecular transition frequencies are useful to develop physics beyond the standard model: detection of electron electric dipole moment, detection of symmetry violation between optical isomers of chiral molecules, and search for the variation in the proton-to-electron mass ratio etc.. The attained systematic frequency is limited by the Stark, Zeeman, and electric quadrupole shifts, which have significant dependence on the electronic states and the angular momentum quantum numbers (electron orbital angular momentum, spin, nuclear spin, molecular rotation, and couplings between them). The molecular pure vibrational transition frequencies without changing any angular momentum quantum numbers are expected to be advantageous for precise measurement, because all frequency shifts at upper and lower states are more than 99 % canceled. Theoretical estimation of attainable accuracies will be given in this presentation.
关键词： electric quadrupole shift,precise measurement,uncertainty,Zeeman shift,Stark shift,molecular transition frequencies
更新于2025-09-12 10:27:22
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Scattering in graphene quantum dots under generalized uncertainty principle
摘要： In this article, the Dirac electron scattering problem on circular barrier of radius R is studied under the generalized uncertainty principle (GUP). The expressions of scattering coefficients, scattering cross-section and scattering efficiency of massless Dirac particle are obtained by solving the massless Dirac equation under GUP and discussed by numerical methods. It shows that the scattering coefficient, the scattering cross-section, and the scattering efficiency depend explicitly on the GUP parameter α. For the scattering coefficient Rl, GUP may cause slight shift in the oscillation position of |Rl|2 and make some peaks value of |Rl|2 smaller. For scattering cross-section and scattering efficiency, GUP may also lead to slight shift in their oscillation position and increase of amplitude when the GUP parameter increases.
关键词： generalized uncertainty principle (GUP),scattering cross-section,Graphene,scattering efficiency,scattering coefficients
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Hyper-Entanglement in Time and Frequency
摘要： Hyper-entanglement, i.e. entanglement in more than one degree of freedom, enables a multiplicative increase in Hilbert space size. Such systems can be treated as multi-partite even though the number of state particles is not increased, making them highly attractive for applications in high-capacity quantum communications and information processing. Until now, such states have been realized only using combinations of fully independent degrees of freedom, described by commuting operators, such as polarization and optical paths. Time and frequency, in turn, are linked and described by non-commuting operators. Here, using two discrete forms of energy-time entanglement we demonstrate that time and frequency can be used for genuine multi-partite hyper-entangled states. This is achieved by increasing the time-frequency product to far exceed the Heisenberg uncertainty limit, effectively making the time and frequency degrees independent.
关键词： time and frequency,hyper-entanglement,quantum communications,information processing,Heisenberg uncertainty limit
更新于2025-09-12 10:27:22
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Experimental test of error-tradeoff uncertainty relation using a continuous-variable entangled state
摘要： Heisenberg’s original uncertainty relation is related to measurement effect, which is different from the preparation uncertainty relation. However, it has been shown that Heisenberg’s error disturbance uncertainty relation is not valid in some cases. We experimentally test the error-tradeoff uncertainty relation by using a continuous-variable Gaussian Einstein–Podolsky–Rosen (EPR)-entangled state. Based on the quantum correlation between the two entangled optical beams, the errors on amplitude and phase quadratures of one EPR optical beam coming from joint measurement are estimated, respectively, which are used to verify the error–tradeoff relation. Especially, the error–tradeoff relation for error-free measurement of one observable is veri?ed in our experiment. We also verify the error–tradeoff relations for nonzero errors and mixed state by introducing loss on one EPR beam. Our experimental results demonstrate that Heisenberg’s error–tradeoff relation is violated in some cases for a continuous-variable system, while the Ozawa’s and Branciard’s relations are valid.
关键词： continuous-variable Gaussian Einstein–Podolsky–Rosen (EPR)-entangled state,error-tradeoff uncertainty relation,quantum correlation,Heisenberg’s uncertainty relation,joint measurement
更新于2025-09-11 14:15:04
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Scale Accuracy Evaluation of Image-Based 3D Reconstruction Strategies Using Laser Photogrammetry
摘要： Rapid developments in the field of underwater photogrammetry have given scientists the ability to produce accurate 3-dimensional (3D) models which are now increasingly used in the representation and study of local areas of interest. This paper addresses the lack of systematic analysis of 3D reconstruction and navigation fusion strategies, as well as associated error evaluation of models produced at larger scales in GPS-denied environments using a monocular camera (often in deep sea scenarios). Based on our prior work on automatic scale estimation of Structure from Motion (SfM)-based 3D models using laser scalers, an automatic scale accuracy framework is presented. The confidence level for each of the scale error estimates is independently assessed through the propagation of the uncertainties associated with image features and laser spot detections using a Monte Carlo simulation. The number of iterations used in the simulation was validated through the analysis of the final estimate behavior. To facilitate the detection and uncertainty estimation of even greatly attenuated laser beams, an automatic laser spot detection method was developed, with the main novelty of estimating the uncertainties based on the recovered characteristic shapes of laser spots with radially decreasing intensities. The effects of four different reconstruction strategies resulting from the combinations of Incremental/Global SfM, and the a priori and a posteriori use of navigation data were analyzed using two distinct survey scenarios captured during the SUBSAINTES 2017 cruise (doi: 10.17600/17001000). The study demonstrates that surveys with multiple overlaps of nonsequential images result in a nearly identical solution regardless of the strategy (SfM or navigation fusion), while surveys with weakly connected sequentially acquired images are prone to produce broad-scale deformation (doming effect) when navigation is not included in the optimization. Thus the scenarios with complex survey patterns substantially benefit from using multiobjective BA navigation fusion. The errors in models, produced by the most appropriate strategy, were estimated at around 1% in the central parts and always inferior to 5% on the extremities. The effects of combining data from multiple surveys were also evaluated. The introduction of additional vectors in the optimization of multisurvey problems successfully accounted for offset changes present in the underwater USBL-based navigation data, and thus minimize the effect of contradicting navigation priors. Our results also illustrate the importance of collecting a multitude of evaluation data at different locations and moments during the survey.
关键词： navigation fusion,laser scalers,uncertainty estimation,structure-from-motion,Monte Carlo simulation,laser spot detection,metrology,underwater 3D reconstruction,multiobjective BA,scale drift evaluation,photogrammetry
更新于2025-09-11 14:15:04
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Switch fault diagnosis for boost DC–DC converters in photovoltaic MPPT systems by using high-gain observers
摘要： Open- and short-circuit faults (OSCFs) in boost dc–dc converters for photovoltaic (PV) maximum power point trackers (MPPTs) imply an inefficiency after fault is triggered, which affect the security and profitability of PV projects. Hence, fault detection and isolation (FDI) techniques have become an important issue for PV technology. In this study, a model-based FDI technique is proposed to boost dc–dc converters in PV MPPT systems. As is well-known, major issues of model-based FDI techniques have always been parametric uncertainty and no-modelled dynamics. This study focuses on how to mitigate these shortcomings by applying a high-gain observer (HGO) as a residual generator. A striking feature of HGO's is that exponential stability is still guaranteed for bounded disturbances (or faults). As demonstrated in this study, under an integral control action in the closed-loop control system, OSCFs are characterised for ever-growing signals, enabling the suggested FDI scheme. Also, the FDI proposal is decoupled from PV current (irradiance changes) and load variations, thereby avoiding false alarms. Moreover, the output-injection gain and thresholds are selected such that the fault diagnosis is achieved in eight switching cycles, enabling a fast and reliable diagnosis. Experimental results are illustrated to validate the FDI scheme proposed in this study.
关键词： photovoltaic MPPT systems,boost dc–dc converters,parametric uncertainty,fault detection and isolation,no-modelled dynamics,high-gain observers
更新于2025-09-11 14:15:04
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Analysis of Electromagnetic Wave Propagation in Variable Magnetized Plasma via Polynomial Chaos Expansion
摘要： A three-dimensional stochastic FDTD algorithm is developed and applied to electromagnetic wave propagation in collisional magnetized plasma characterized by a variable electron density, collision frequency, and background magnetic ?eld. The proposed stochastic model is based on the expansion of the random / variable time-domain electric and magnetic ?elds in terms of orthogonal polynomials in independent random variables representative of the variable ionospheric content. Electromagnetic wave propagation in magnetized plasma having low variability (small deviations) and also high variability (large deviations) of the electron density, collision frequency, and background magnetic ?eld is studied. The stochastic algorithm is validated against brute-force Monte Carlo results. The algorithm is considerably more computationally ef?cient than Monte Carlo. When applied to electromagnetic wave propagation in the ionosphere, the variability of the Earth’s magnetic ?eld and ionospheric parameters can be accounted for due to naturally varying space weather conditions and day-to-day variations, measurement errors, etc. Although only electrons are considered here, positive and negative ions may be accommodated in a straight-forward manner.
关键词： ?nite-difference time-domain (FDTD),electromagnetic wave propagation,ionosphere,polynomial chaos,uncertainty,collisional magnetized cold plasma
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Sampling AC Signals: Comparison of Fitting Algorithms and FFT
摘要： Fitting algorithms and FFT are commonly used to determine the RMS value and the phase of AC signals. This paper focusses on metrology applications and compares different algorithms with respect to their uncertainty contribution. The study covers pure sinewave signals, signals with noise and signals with cross-talk from a power line. The results are experimentally veri?ed using an AC Josephson voltage source. The paper shows that the DC performance of the sampling system can be used for AC signals. The uncertainty contribution of the algorithms is negligible if the algorithm is chosen carefully.
关键词： Fitting,sampling,measurement uncertainty,uncertainty,measurement techniques,Measurement,FFT
更新于2025-09-10 09:29:36