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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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Effect of image processing constraints on the extent of rotational ambiguity in MCR-ALS of hyperspectral images
摘要： Hyperspectral imaging is a way to explore the spatial and spectral information of the different compounds in chemical or biological samples. In addition, multivariate curve resolution alternating least squares (MCR-ALS) can be used to extract this information based on the bilinearity assumption. However, it is well-known that using proper constraints can reduce the amount of uncertainty in the results of MCR, which is called rotational ambiguity. In MCR-ALS analysis of hyperspectral images, different image processing techniques, such as model fitting, image segmentation or sparse image recovery can be applied as spatial constraints. In this contribution, we aim to investigate how the use of these spatial constraints limits the extent of rotational ambiguity of MCR-ALS solutions. For this purpose, we evaluate the extent of rotational ambiguity and use Borgen plots to visualize it. We show on simulations and real hyperspectral imaging data that accuracy of the results is improved when spatial constraints are applied.
关键词： Borgen plot,Uncertainty,Area of feasible solutions,Spatial constraints,Multivariate Curve Resolution - Alternating Least Squares
更新于2025-09-09 09:28:46
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Active Guarded Wheatstone Bridge for High Resistance Measurements Up to 100 TΩ at TüB?TAK UME
摘要： We present an active guarded Wheatstone bridge, developed at TüB?TAK UME, for high resistance measurements between 100 MΩ to 100 TΩ up to 1000 V. The guarded box connections and special low noise cables were used to reduce noise and leakage currents causing measurement errors. This has enabled us to perform stable measurements at higher resistor values.
关键词： guard resistor,measurement uncertainty,Wheatstone bridge,high value resistance,low current
更新于2025-09-09 09:28:46
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Visual-quality Guided Global Backlight Dimming for Video Display on Mobile Devices
摘要： This paper proposes a visual-quality guided global backlight dimming (VQG-GBD) algorithm to reduce the power consumption of liquid-crystal display (LCD) on mobile devices. We build a backlight scaling ratio (BSR) prediction model via visual quality assessment (VQA) which considers not only display contents but also backlight intensity while measuring video quality. Also, we add visual uncertainty as an indicator to dim the backlight without being noticed by observers. VQG-GBD includes a training stage and online stage. For training stage, firstly, we collect videos with distinct attributes of brightness and uncertainty. Then, subjective rating obtains the relationship among visual quality, BSR, brightness, and visual uncertainty. Finally, we use the trust-region method (TRM) to build the BSR prediction model. In online stage, the model is applied to mobile devices for real-time video display. And a BSR optimization strategy is proposed to eliminate the flicker effect between frames, followed by three techniques to accelerate the process: motion vector (MV) extraction and pixel subsampling reduce the computation while analyzing frame content; GPU rendering speed up the pixel compensation. Experimental results show that VQG-GBD achieves averagely 21% of power demand reduction for displaying video on mobile devices while preserving good visual quality. VQG-GBD delivers more power reduction than the state-of-the-art algorithm image integrity-based gray-level error control (I2GEC) and multi-histogram-based gray-level error control (MGEC) by 10% and 8% respectively.
关键词： Global backlight dimming,mobile devices,visual uncertainty,ACR11,subjective visual quality assessment,liquid-crystal display,trust-region method
更新于2025-09-09 09:28:46
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Numerical Simulation of Focused Wave and Its Uncertainty Analysis
摘要： On the basis of the transient water wave (TWW) theory, focused wave is generated in the circulating water channel. Numerical simulation of the focused wave is carried out by solving the Reynolds averaged Navier-Stokes (RANS) equations. The dynamic grid technique is adopted to simulate the motion of the wave maker, and the volume of ?uid (VOF) method is used to capture the free surface of the wave. The simulation results are compared with the measured data, and good agreement is obtained. For quantitative estimation of the numerical simulation error and uncertainty, the uncertainty analysis method recommended by the International Towing Tank Conference (ITTC) procedure is performed for the simulation results of the surface elevations at di?erent positions. Both grid-convergence and time-step-size convergence studies are conducted using three types of grids and time step sizes. The simulation results are all monotonously convergent in the veri?cation procedure, and the validations of the simulated surface elevations with the positions at 3.5, 4.0 and 4.5 m are all achieved by comparing with the validation uncertainty. It is found that the numerical simulation errors caused by the grid and time-step-size in the convergence studies have the same order of magnitude. In addition, the numerical errors and uncertainties for the surface elevations at di?erent positions are compared and discussed in detail. This paper presents the ?rst attempt to carry out the uncertainty analysis of the simulation of focused wave, and the e?ectiveness of the proposed veri?cation and validation procedures in the uncertainty analysis is demonstrated.
关键词： Reynolds averaged Navier-Stokes (RANS) equations,validation,uncertainty analysis,veri?cation,focused wave
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Uncertainty Quantification for Reflector Antennas
摘要： Large re?ector antennas for telecommunication or space observation purposes often require a lengthy and detailed design process, where the design is carefully revised to ensure the best performance for the intended application. For many modern re?ector antennas, quanti?cation of the uncertainty in performance as a function of manufacturing errors is an important part of the design process. In this paper, we present an ef?cient way of quantifying the effects of uncertainty in the production. The method is shown to far outperform the conventional Monte-Carlo techniques in accuracy and computational time.
关键词： uncertainty quanti?cation,re?ector antennas
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Efficient Uncertainty Evaluation of Vector Network Analyser Measurements Using Two-Tier Bayesian Analysis and Monte Carlo Method
摘要： Antennas are a key element in any communication system and vector network analyser (VNA) is popular tool for charactering antenna impedance bandwidth. In this paper, an efficient uncertainty evaluation method is proposed for VNA measurement based on its uncertainty propagation mechanism using Bayesian analysis and Monte Carlo method. The proposed method is generic and can be applied to VNA with arbitrary number of ports. In order to obtain the complete information of measurement uncertainty distribution, a two-tier Bayesian analytic process is carried out. The proposed method contains three steps. In the first step, the posterior distribution of each uncertainty source of VNA calibrations is deduced by the use of prior and current sample information through the first-tier Bayesian analysis. In the second step, the obtained posterior distributions of uncertainty sources are taken into the Monte Carlo simulation of one-port VNA measurement uncertainties. In the last step, the results obtained in the second step are used as the prior distribution of the secondary Bayesian evaluation, then the evaluation results of the measurement uncertainty can be obtained with the means, variances and skewness of the probabilistic distribution. The numerical analysis using an antenna measurement results demonstrate the high-efficiency and reliability of this proposed method.
关键词： Bayesian analysis,VNA,uncertainty,Monte Carlo simulation,measurement
更新于2025-09-04 15:30:14
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Performance Evaluation of Radiation Sensors for the Solar Energy Sector
摘要： Rotating Shadowband Irradiometers (RSI) and SPN1 Sunshine Pyranometers allow determining the diffuse and direct components of solar radiation without sun trackers; they can be deployed in networks for continuous field operation with modest maintenance. Their performances are evaluated here by analyzing their errors with respect to well characterized references. The analysis is based on 1-minute data recorded over a 15-month period at the Payerne BSRN station in Switzerland. The analysis was applied both to the whole dataset and data subsets reflecting particular conditions to allow a better understanding of how instrument performance depends on such conditions.
关键词： accuracy,RSI,rotating shadowband irradiometer,shortwave radiation,pyranometer,SPN1,uncertainty
更新于2025-09-04 15:30:14
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Transition rate and the photoelectric effect in the presence of a minimal length
摘要： In this work, according to the generalized uncertainty principle (GUP) and time-dependent perturbation theory, the transition rate in the present of a minimal length based on the Kempf algebra is studied. Also, we ?nd the absorption cross section in the framework of the GUP. The modi?ed photoelectric effect is investigated and we show that the differential cross section of the photoelectric effect in the framework of the GUP is related to the isotropic minimal length scale. The upper bound on the isotropic minimal length is estimated.
关键词： absorption cross section,minimal length,generalized uncertainty principle,transition rate,photoelectric effect
更新于2025-09-04 15:30:14
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Exploration of entropic uncertainty relation for two accelerating atoms immersed in a bath of electromagnetic field
摘要： The uncertainty principle as an elementary theory of quantum mechanics plays an important role in quantum information science. In this paper, we study the dynamics of quantum-memory-assisted entropic uncertainty relation for two accelerating atoms coupled with a bath of fluctuating electromagnetic field. The master equation that the system evolution obeys is firstly derived. We find that the mixedness is bound up with the entropic uncertainty. For equilibrium state, the tightness of uncertainty vanishes. For the initial maximum entangled state, the tightness of uncertainty experiences a slight increase and then declines to zero with evolution time. It is found that the greater acceleration makes the uncertainty faster reach a maximum value and stable value. For a fixed acceleration, the uncertainty with different two-atom separations converges to a fixed value. Furthermore, we utilize weak measurement reversal to manipulate the entropic uncertainty. Our explorations may suggest a method of probing entanglement, acceleration effect and vacuum fluctuation effect with entropic uncertainty.
关键词： Fluctuating electromagnetic field,Weak measurement reversal,Dynamics,Mixedness,Entropic uncertainty
更新于2025-09-04 15:30:14