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Determining Series Resistance for Equivalent Circuit Models of a PV Module
摘要： Literature describes various methods for determining a series resistance for a photovoltaic device from measured IV curves. We investigate use of these techniques to estimate the series resistance parameter for a single diode equivalent circuit model. With simulated IV curves we demonstrate that the series resistance values obtained by these techniques differ systematically from the known series resistance parameter values used to generate the curves, indicating that these methods are not suitable for determining the series resistance parameter for the single diode model equation. We present an alternative method to determine the series resistance parameter jointly with the other parameters for the single diode model equation, and demonstrate the accuracy and reliability of this technique in the presence of measurement errors.
关键词： Current-voltage characteristics,parameter extraction,electric resistance,solar panels
更新于2025-09-23 15:22:29
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Response of Inner Retinal Oxygen Extraction Fraction to Light Flicker Under Normoxia and Hypoxia in Rat
摘要： PURPOSE. Oxygen extraction fraction (OEF), defined by the ratio of oxygen metabolism (MO2) to delivery (DO2), determines the level of compensation of MO2 by DO2. In the current study, we tested the hypothesis that inner retinal OEF remains unchanged during light flicker under systemic normoxia and hypoxia in rats due to the matching of MO2 and DO2. METHODS. Retinal vascular oxygen tension (PO2) measurements were obtained in 10 rats by phosphorescence lifetime imaging. Inner retinal OEF was derived from vascular PO2 based on Fick's principle. Measurements were obtained before and during light flicker under systemic normoxia and hypoxia. The effects of light flicker and systemic oxygenation on retinal vascular PO2 and OEF were determined by ANOVA. RESULTS. During light flicker, retinal venous PO2 decreased (P < 0.01, N = 10), while inner retinal OEF increased (P = 0.02). Under hypoxia, retinal arterial and venous PO2 decreased (P < 0.01), while OEF increased (P < 0.01). The interaction effect was not significant on OEF (P = 0.52), indicating the responses of OEF to light flicker were similar under normoxia and hypoxia. During light flicker, OEF increased from 0.46 ± 0.13 to 0.50 ± 0.11 under normoxia, while under hypoxia, OEF increased from 0.67 ± 0.16 to 0.74 ± 0.14. CONCLUSIONS. Inner retinal OEF increased during light flicker, indicating the relative change in DO2 is less than that in MO2 in rats under systemic normoxia and hypoxia. Inner retinal OEF is a potentially useful parameter for assessment of the relative changes of MO2 and DO2 under physiologic and pathologic conditions.
关键词： vascular oxygen tension,retina,oxygen extraction fraction,hypoxia,light flicker
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Comparative Study of Feature Extraction Approaches for Ship Classification in Moderate-Resolution SAR Imagery
摘要： This paper presents a comparative study of existing feature extraction approaches for ship classification in moderate-resolution synthetic aperture radar (SAR) images. Ship classification is a key functionality in many maritime surveillance applications. For efficient ship classification, appropriate feature extraction is crucial. Most of existing studies have used high-resolution images. For maritime surveillance, however, wide-area coverage is essential whereas it inevitably reduces the spatial resolution. In this paper, we evaluate the applicability of representative methods to moderate-resolution images. The evaluated methods are hand-crafted feature extraction (HCF), principal component analysis (PCA) and autoencoder (AE) based on neural-network. The evaluation is done on the basis of accuracy for two-class ship classification into tanker and cargo. The experiments demonstrate that AE outperforms HCF and PCA in classification accuracy by 7.4% and 2.6%, respectively. Furthermore, AE performs best even in classification of challenging cases such as small ships.
关键词： feature extraction,ship classification,moderate resolution,deep learning,SAR,maritime
更新于2025-09-23 15:22:29
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Comparison of the posterior corneal elevation and biomechanics after SMILE and LASEK for myopia: a short- and long-term observation
摘要： Purpose This study compares the posterior corneal elevation and corneal biomechanics after small incision lenticule extraction (SMILE) and laser-assisted subepithelial keratomileusis (LASEK) for myopia correction in a short- and long-term observation. Methods This prospective study included 32 patients in the SMILE group and 32 patients in the LASEK group. Corneal posterior central elevation (PCE), posterior mean elevation (PME), corneal back power (Kb), and anterior chamber depth (ACD) were evaluated with Pentacam, and intraocular pressure (IOP), corneal hysteresis (CH), and corneal resistance factor (CRF) were evaluated with the ORA at pre-operation and 3 months and 3 years post-operation. Results Three months post-operatively, CH, CRF, and IOP decreased significantly and central posterior surface shifted backward in both groups (p < 0.05). CH was lower in the LASEK group (p = 0.03) and change of CH and CRF per unit corneal tissue removed (ΔCH/ablation depth (AD) and ΔCRF/AD) was lower in SMILE than in LASEK (p = 0.01, 0.03). Three years post-operatively, the PME shifted more posteriorly in LASEK (p = 0.04), but was stable in SMILE (p = 0.06). Kb flattened and ACD was shallower in both groups (compared to preoperative data, p < 0.001). CH in the LASEK group increased and is comparable to that in the SMILE group at 3 years post-operative. Conclusion Both SMILE and LASEK can change the posterior surface and corneal biomechanics. SMILE may have less influence on corneal biomechanics than LASEK at an early stage post-operative in terms of per unit corneal tissue removed, but the effect became comparable in a long-term observation.
关键词： Corneal biomechanics,Corneal posterior elevation,Small incision lenticule extraction,Laser-assisted subepithelial keratomileusis
更新于2025-09-23 15:22:29
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Deep Belief Network for Spectral–Spatial Classification of Hyperspectral Remote Sensor Data
摘要： With the development of high-resolution optical sensors, the classification of ground objects combined with multivariate optical sensors is a hot topic at present. Deep learning methods, such as convolutional neural networks, are applied to feature extraction and classification. In this work, a novel deep belief network (DBN) hyperspectral image classification method based on multivariate optical sensors and stacked by restricted Boltzmann machines is proposed. We introduced the DBN framework to classify spatial hyperspectral sensor data on the basis of DBN. Then, the improved method (combination of spectral and spatial information) was verified. After unsupervised pretraining and supervised fine-tuning, the DBN model could successfully learn features. Additionally, we added a logistic regression layer that could classify the hyperspectral images. Moreover, the proposed training method, which fuses spectral and spatial information, was tested over the Indian Pines and Pavia University datasets. The advantages of this method over traditional methods are as follows: (1) the network has deep structure and the ability of feature extraction is stronger than traditional classifiers; (2) experimental results indicate that our method outperforms traditional classification and other deep learning approaches.
关键词： classification,feature extraction,multi-sensor fusion,remote sensors,deep learning,hyperspectral image
更新于2025-09-23 15:22:29
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Preoperative automatic visual behavioural analysis as a tool for intraocular lens choice in cataract surgery
摘要： Purpose: Cataract is the main cause of blindness, affecting 18 million people worldwide, with the highest incidence in the population above 50 years of age. Low visual acuity caused by cataract may have a negative impact on patient quality of life. The current treatment is surgery in order to replace the natural lens with an artificial intraocular lens (IOL), which can be mono- or multifocal. However, due to potential side effects, IOLs must be carefully chosen to ensure higher patient satisfaction. Thus, studies on the visual behavior of these patients may be an important tool to determine the best type of IOL implantation. This study proposed an anamnestic add-on for optimizing the choice of IOL. Methods: We used a camera that automatically takes pictures, documenting the patient’s visual routine in order to obtain additional information about the frequency of distant, intermediate, and near sights. Results: The results indicated an estimated frequency percentage, suggesting that visual analysis of routine photographic records of a patient with cataract may be useful for understanding behavioural gaze and for choosing visual management strategy after cataract surgery, simultaneously stimulating interest for customized IOL manufacturing according to individual needs.
关键词： Sickness impact profile,Cataract/psychology,Cataract extraction,Vision, ocular,Visual acuity,Lenses, intraocular,Quality of life
更新于2025-09-23 15:22:29
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[Lecture Notes in Computational Vision and Biomechanics] Computer Aided Intervention and Diagnostics in Clinical and Medical Images Volume 31 || Segmentation of Type II Diabetic Patient’s Retinal Blood Vessel to Diagnose Diabetic Retinopathy
摘要： Diabetic Retinopathy is one of the ophthalmic reasons for visual deficiency. The favored fixate of consideration is on the estimation of deviation in the breadth of the retinal veins and the new vessel development. To witness the progressions, segmentation has to be made primarily. A framework to improve the quality of the segmentation result over pathological retinal images is proposed. The proposed method uses adaptive histogram equalizer for preprocessing, pulse coupled neural Network model for automatic feature vector generation and extraction of the retinal blood vessels. The test result represents that the proposed method is enhanced than other retinal competitive methods. The evaluation of the proposed approach is executed over standard public DRIVE, STARE, REVIEW, HRF, and DRIONS fundus image datasets. The proposed technique improves the segmentation results in terms of sensitivity, specificity, and accuracy.
关键词： Fundus image,Feature extraction,Diabetic Retinopathy,Retinal blood vessel,Medical imaging
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Asian Solid-State Circuits Conference (A-SSCC) - Tainan, Taiwan (2018.11.5-2018.11.7)] 2018 IEEE Asian Solid-State Circuits Conference (A-SSCC) - A 137-μW Area-Efficient Real-Time Gesture Recognition System for Smart Wearable Devices
摘要： Gesture recognition has increasingly become one of the most popular human-machine interaction techniques for smart devices. Existing gesture recognition systems suffer from either excessive power consumption or large size, limiting their applications for ultra-low power IoT and wearable devices. This paper presents an accurate, area-efficient, and ultra-low power real-time gesture recognition system for smart wearable devices. The proposed work utilizes a peak-based gesture classification engine with less memory and a low-resolution and low-power on-chip image sensor for achieving high area efficiency and low power. The feature extraction architecture removes fixed-pattern noises from the low-power on-chip image sensor for accuracy improvement and employs parallelism for recognition speed enhancement. The proposed system requires only 3.2 KB on-chip memory for processing 32x32 pixel data. Measurement results of a test chip fabricated in 65nm CMOS demonstrate that the proposed system consumes 137.0 pW at 0.8 V and 30fps while occupying only 1.78mm2, which achieves the lowest power and smallest area among existing gesture recognition systems.
关键词： system on chip,low power processor,image sensor,wearable devices,gesture recognition,feature extraction
更新于2025-09-23 15:22:29
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Online Junction Temperature Extraction of SiC Power MOSFETs with Temperature Sensitive Optic Parameter (TSOP) Approach
摘要： Accurate information of the junction temperature of SiC power MOSFETs ensures safe operation and helps reliability assessment of the devices. In this paper, an online junction temperature extraction method is proposed based on the electroluminescence phenomenon of the body diode of SiC power MOSFETs. It is found that during the forward conduction interval of the body diode, visible blue light is emitted around the chip, which ascribes to the radiative recombination in the low doped region of SiC MOSFETs. Experimental results suggest the light intensity changes linearly with the variation of the temperature and behaves as a temperature sensitive optic parameter (TSOP). Further, an electro-thermal-optic model is proposed to reveal the relationship between electroluminescence intensity, forward current and junction temperature. Based on the TSOP, an online junction temperature extraction method is proposed for SiC MOSFETs and verified in a SiC MOSFET based inverter. Compared with state-of-the-art methods, the proposed junction temperature measurement method is contactless and immune from the aging of the package.
关键词： junction temperature extraction,Body diode,thermal management,electroluminescence,SiC MOSFETs
更新于2025-09-23 15:22:29
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Effects of reaction conditions on light-dependent silver nanoparticle biosynthesis mediated by cell extract of green alga Neochloris oleoabundans
摘要： Silver nanoparticles (AgNPs) were synthesized by incubating the mixture of AgNO3 solution and whole-cell aqueous extracts (WCAEs) of Neochloris oleoabundans under light conditions. By conducting single-factor and multi-factor optimization, the effects of parameters including AgNO3 concentration, pH, and extraction time were quantitatively evaluated. The optimal conditions in terms of AgNP yield were found to be 0.8 mM AgNO3, pH 5, and 9-h extraction. The AgNPs thus synthesized were quasi-spherical with a mean particle diameter of 16.63 nm and exhibited decent uniformity as well as antibacterial activities, which may facilitate AgNP biosynthesis’s application in the near future.
关键词： Extraction time,Biosynthesis,Silver nanoparticles,Light-dependent reaction,AgNO3 concentration,pH,Microalgae
更新于2025-09-23 15:21:21