1,568 research outputs found
Accurate calibration of the four-detector photopolarimeter with imperfect polarizing optical elements
The first three columns of the instrument matrix A of the four-detector photopolarimeter (FDP) are determined by Fourier analysis of the output current vector I(P) as a function of the azimuth angle P of the incident linearly polarized light. Therefore 12 of the 16 elements of A are measured free of the imperfections of the (absent) quarter-wave retarder (QWR). The effect of angular beam deviation by the polarizer is compensated for by taking the average, (1/2) [I(P) + I(P + 180°)], of the FDP output at 180°-apart, optically equivalent, angular positions of the polarizer. The remaining fourth column of A is determined by the FDP’s response to the right- and left-handed circular polarization states. Because these states are impossible to generate with an imperfect QWR, a novel procedure is developed. In particular, the response of the FDP to the unattainable right- or left-handed circular polarization state is found by taking the average of the responses of the FDP to an elliptical near-circular state and that state rotated in azimuth by 90°. This calibration scheme is applied to measure A of our prototype FDP of four Si detectors at λ = 632.8 nm. A is determined, in external and internal reference frames, free of imperfections in the polarizing optical elements. The FDP, with its uncontaminated A matrix, is used subsequently to evaluate the imperfections of the QWR with the help of an appropriate model
Low-Frequency Load Identification using CNN-BiLSTM Attention Mechanism
Non-intrusive Load Monitoring (NILM) is an established technique for
effective and cost-efficient electricity consumption management. The method is
used to estimate appliance-level power consumption from aggregated power
measurements. This paper presents a hybrid learning approach, consisting of a
convolutional neural network (CNN) and a bidirectional long short-term memory
(BILSTM), featuring an integrated attention mechanism, all within the context
of disaggregating low-frequency power data. While prior research has been
mainly focused on high-frequency data disaggregation, our study takes a
distinct direction by concentrating on low-frequency data. The proposed hybrid
CNN-BILSTM model is adept at extracting both temporal (time-related) and
spatial (location-related) features, allowing it to precisely identify energy
consumption patterns at the appliance level. This accuracy is further enhanced
by the attention mechanism, which aids the model in pinpointing crucial parts
of the data for more precise event detection and load disaggregation. We
conduct simulations using the existing low-frequency REDD dataset to assess our
model performance. The results demonstrate that our proposed approach
outperforms existing methods in terms of accuracy and computation time
Validation of a New Duplex Derived Haemodynamic Effectiveness Score, the Saphenous Treatment Score, in Quantifying Varicose Vein Treatments
AbstractObjectivesTo evaluate a duplex-derived score for varicose vein treatments using numerical values of haemodynamic effectiveness.DesignThe saphenous treatment score (STS) was developed prospectively to compare the effect of endovenous treatments on reflux within saphenous segments.PatientsSixty-six patients were randomised to endovenous laser ablation (EVLA) or ultrasound-guided foam sclerotherapy (UGFS) to the great saphenous vein (GSV).MethodsAssessments included the Aberdeen varicose vein severity score (AVVSS), the venous clinical severity score (VCSS), the venous filling index (VFI) and the STS.ResultsA mean STS of 5.70 decreased to 3.30, P < .0005, post-treatment. The median (IQR) AVVSS, VCSS and VFI (ml/sec) decreased from 21.52(15.48) to 18.86(11.27), P = .14, from 6(4) to 3(4), P < .0005 and from 7.1(6.9) to 1.9(.9) P < .0005, respectively. In 15 patients requiring additional UGFS the mean STS values decreased from 5.8 to 4.13 and then to 2.6 P < .0005, respectively. The individual above and below knee mean treatment differences in STS on 38 EVLA and 28 UGFS patients were 1.92 and .87 (EVLA) compared to 1.57and .29 (UGFS) P = .001, respectively.ConclusionsThe STS has been shown to grade the haemodynamic effects of different treatments as well as ongoing treatments on the GSV
Experimental determination of the degree of quantum polarisation of continuous variable states
We demonstrate excitation-manifold resolved polarisation characterisation of
continuous-variable (CV) quantum states. In contrast to traditional
characterisation of polarisation that is based on the Stokes parameters, we
experimentally determine the Stokes vector of each excitation manifold
separately. Only for states with a given photon number does the methods
coincide. For states with an indeterminate photon number, for example Gaussian
states, the employed method gives a richer and more accurate description. We
apply the method both in theory and in experiment to some common states to
demonstrate its advantages.Comment: 5 page
Experimental Polarization State Tomography using Optimal Polarimeters
We report on the experimental implementation of a polarimeter based on a
scheme known to be optimal for obtaining the polarization vector of ensembles
of spin-1/2 quantum systems, and the alignment procedure for this polarimeter
is discussed. We also show how to use this polarimeter to estimate the
polarization state for identically prepared ensembles of single photons and
photon pairs and extend the method to obtain the density matrix for generic
multi-photon states. State reconstruction and performance of the polarimeter is
illustrated by actual measurements on identically prepared ensembles of single
photons and polarization entangled photon pairs
Line tension and structure of smectic liquid crystal multilayers at the air-water interface
At the air/water interface, 4,-8-alkyl[1,1,-biphenyl]-4-carbonitrile (8CB)
domains with different thicknesses coexist in the same Langmuir film, as
multiple bilayers on a monolayer. The edge dislocation at the domain boundary
leads to line tension, which determines the domain shape and dynamics. By
observing the domain relaxation process starting from small distortions, we
find that the line tension is linearly dependent on the thickness difference
between the coexisting phases in the film. Comparisons with theoretical
treatments in the literature suggest that the edge dislocation at the boundary
locates near the center of the film, which means that the 8CB multilayers are
almost symmetric with respect to the air/water interface.Comment: 21 pages, 6 figure
- …