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[IEEE 2018 7th International Conference on Agro-geoinformatics (Agro-geoinformatics) - Hangzhou (2018.8.6-2018.8.9)] 2018 7th International Conference on Agro-geoinformatics (Agro-geoinformatics) - Retrieval of Leaf Chlorophyll Content of Paddy Rice with Extracted Foliar Hyperspectral Imagery
摘要： Retrieving foliar chlorophyll content with canopy spectral data is critical for understanding the growing status and yield estimation of paddy rice. However, given the field of view of rice canopy is a mixture of plant organs (i.e., leaves, stems and spikes) and backgrounds (i.e., water, soil and gaps), spectral signals from the targeted portions were disturbed by other portions, thus result in a limited accuracy for foliar chlorophyll content estimation, particularly when the canopy closure was low. As an advanced remote sensing technology, hyperspectral imaging sensors could collect information from both image and spectral dimensions, which allows identification and separation of different plant portions and backgrounds within the scene. Based on this principle, this paper proposed a method using refined spectrum for retrieving rice foliar chlorophyll content. The experimental data consisted of 58 hyperspectral images of rice canopy that were obtained by a Cubert S185 hyperspectral imager. Besides, corresponding chlorophyll content of rice leaves was measured with a SPAD meter. To retrieve foliar chlorophyll contents with refined spectra, a spectral purification procedure was established. Background of rice images was firstly removed by a decision tree method. Then, rice spikes could be removed according to an object-oriented classification which thus left the portion of rice leaves. Vegetation indices were extracted from the refined leaf spectra and were correlated with foliar chlorophyll content. Comparing with the performance of vegetation indices with original canopy hyperspectral data in retrieving foliar chlorophyll content, results suggested that retrieving accuracy based on refined spectra resulted in a significant improvement. The proposed spectral purification procedure helps to mitigate the background impact by wiping out those non-target spectral signals, which thus substantially improve the retrieval accuracy. Such a method can lay a good foundation for subsequent development of some built-in algorithms for in-situ sensors and UAV remote sensing platforms.
关键词： Chlorophyll Content,Spectral purification,Retrieving Accuracy,Hyperspectral
更新于2025-09-11 14:15:04
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - The Simulation of Ocean Surface Wind Measured by Polarimetric Scatterometer
摘要： Ocean surface wind field is a very important marine dynamic parameter in marine environment forecasting and climatological studies. Spaceborne scatterometer is one of the most efficient remote sensors than can provide global ocean surface wind measurement. Polarimetric scatterometer (PolScat) simultaneously measures co-polarized and cross-polarized backscattering coefficient and the correlation coefficient of the co- and cross-polarized component of radar echoes which can significantly improve the performance of the sea surface wind field measurements. In this paper, we derive the error model of correlation scattering coefficient from radar echo signals. The effect of antenna polaxis deflection on correlation scattering coefficient error is analyzed. Moreover, an “end-to-end” system simulation model of PolScat is established. A modified Maximum Likelihood Estimation (MLE) is used for ocean surface wind field inversion. Both the co-polarized backscattering coefficient and correlation scattering coefficient are included in the objective function of MLE. The simulation results show that PolScat can effectively reduce the probability of ambiguous solutions. The wind speed and wind direction inversion accuracy of PolScat is better than 1m/s and 15° respectively.
关键词： inversion accuracy,system simulation,ocean surface wind vector,Polarimetric scatterometer
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Deconvolution Approaches for Resolution Enhancement with DPS Scatterometer
摘要： Based on [1]，a quantitative comparison of resolution enhancement performance for three deconvolution approaches (L2 norm, L1 norm and TV) to DPS scatterometer over nadir swath are made. The spatial resolution and reconstruction accuracy/precision properties of these methods are analyzed and compared. Results show that resolution enhancement is achieved by the price of decreased accuracy/precision of reconstructed backscatter, and the reconstructed backscatter becomes a more smoothed version of truth backscatter with decrease of spatial resolution.
关键词： resolution enhancement,DPS,accuracy/precision,deconvolution method
更新于2025-09-10 09:29:36
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Coding patterns used by ophthalmologists for hydroxychloroquine retinal toxicity
摘要： The aim of this study was to characterize International Classification of Diseases (ICD-9) coding patterns used by ophthalmologists in clinical practice for hydroxychloroquine (HCQ) retinal toxicity. This is a retrospective cohort study. Patients enrolled in the Kaiser Permanente Southern California health plan who were dispensed HCQ between 2001 and 2014 were included in this study. Patients’ medical records were electronically searched for the following ICD-9 codes that can be used to characterize retinopathy or maculopathy: toxic maculopathy, non-exudative age-related macular degeneration (AMD), drusen (degenerative), and/or (other) background retinopathy. The charts of patients with these codes were then manually reviewed to determine which of these patients had been diagnosed by their ophthalmologists with HCQ retinopathy. A total of 23,362 patients were dispensed HCQ between 2001 and 2014. Of whom, 678 (2.9%) patients received at least one of the aforementioned ICD-9 codes with 53 having confirmed HCQ toxicity on chart review. Forty-three patients who were taking HCQ received a diagnosis code for toxic maculopathy, and of whom, 35 (81.4%) had HCQ toxicity. Of the patients with confirmed HCQ toxicity, 32.1% received a code other than toxic maculopathy to connote the presence of disease. Although toxic maculopathy is the most commonly used ICD-9 code to identify patients with HCQ toxicity, a significant number of patients with toxicity received other codes in their medical records. Additionally, almost one-fifth of the patients who were coded as having toxic maculopathy were ultimately not diagnosed with HCQ toxicity. This study underscores the often imprecise nature of ICD coding, especially in conditions without a specific associated code. The limitations of using coding information should also be considered when conducting research that utilizes electronic databases. Future investigations should determine how to improve database searches and methods to create more uniform coding standards among ophthalmologists, especially for rare conditions such as HCQ toxicity.
关键词： International Classification of Diseases,retinopathy,plaquenil,database,coding,accuracy,hydroxychloroquine,billing
更新于2025-09-10 09:29:36
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Block Adjustment without GCPs for Chinese Spaceborne SAR GF-3 Imagery
摘要： The Gaofen-3 (GF-3) satellite is the first C-band multi-polarization synthetic aperture radar (SAR) with the ability of high-accuracy mapping in China. However, the Ground Control Points (GCPs) are essential to ensure the accuracy of mapping for GF-3 SAR imagery at present. In this paper, we analyze the error sources that affect the geometric processing and propose a new block adjustment method without GCPs for GF-3 SAR imagery. Firstly, the geometric calibration of GF-3 image is carried out. Secondly, the rational polynomial coefficient (RPC) model is directly generated after the geometric calibration parameters compensation of each image. Finally, we solve the orientation parameters of the GF-3 images through DEM assisted planar block adjustment and conduct ortho-rectification. With two different imaging modes of GF-3 satellite, which include the QPSI and FS2, we carry out the block adjustment without GCPs. Experimental results of testing areas including Wuhan city and Hubei province in China show that the geometric mosaic accuracy and the absolute positioning accuracy of the orthophoto are better than one pixel, which has laid a good foundation for the application of GF-3 image in global high-accuracy mapping.
关键词： RPC,without GCPs,GF-3,accuracy,geometric calibration,planar block adjustment
更新于2025-09-10 09:29:36
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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) - Development of Power Frequency Digital Phase Shifter
摘要： In the measurement of high voltage loss, a voltage signal and a current signal which were nearly orthogonal to each other need to be measured accurately. If the phase of the voltage signal was shifted by 90° accurately, thus the phase angle between the voltage and the current would be nearly 0°. The two signals would be then easily to measure accurately together. A digital phase shifter was developed. The phase and the magnitude error of the digital phase shifter is less than 6 μrad and 110 × 10-6 up to 150 Hz and 120 V, respectively.
关键词： phase shifter,loss measurement,phase accuracy,Analog-to-Digital Convertor (ADC),Digital-to-Analog Convertor (DAC)
更新于2025-09-10 09:29:36
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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) - Progress in Fluxgate Current Transducers
摘要： This paper describes recent technological progress in the field of high accuracy fluxgate current transducers. After an introduction into the subject, followed by advantages and limitations, innovative waveforms for fluxgate excitation and their digital signal processing are described in more detail, followed by an explanation of key performance parameters of a new product.
关键词： Current measurement,ripple suppression,low noise,digital signal processing,high accuracy,fluxgate
更新于2025-09-10 09:29:36
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Design, simulation, and hardware implementation of novel optimum operating point tracker of PV system using adaptive step size
摘要： In this paper, a novel maximum power point tracking (MPPT) strategy of photovoltaic system has been proposed and investigated. The suggested method is based on modified variable step-size perturbation and observation P&O strategy, which it can overcome several drawbacks and limitations of previous developed MPPT methods especially oscillations around the MPP, accuracy, and the convergence speed under rapidly changing atmospheric conditions. To demonstrate the efficiency of the proposed method, both simulation model and experimental prototype have been developed and tested effectively using photovoltaic system based on Solarex MSX-60 panel and forward converter controlled by dsPIC30F2010 controller. Obtained results demonstrate that the proposed adaptive step-length perturbation and observation P&O strategy can offer many benefits compared to conventional P&O MPPT method and other methods developed previously in terms of low ripple, low overshoot, and low response time. The proposed adaptive step-size MPPT improves drastically the performances in static mode (oscillation reduction ratio around 75.00%) as well as in dynamic mode (convergence time reduction ratio around 91.67%) improving by the way the transferred available power.
关键词： New modified P&O MPPT algorithm,Variable step-size MPPT algorithm,dspic30f2010,Tracking and accuracy of MPP,Forward converter,Implementation
更新于2025-09-10 09:29:36
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0561 Lipolysis effect on milk fat and protein analysis by infrared spectroscopy using filter and Fourier transform infrared (FTIR) methods
摘要： on performance determined in advance using laser light scattering particle size analysis. Milk that was externally homogenized and unhomogenized milk were each tested 18 times in sequence, producing predicted values for fat B, fat A, fat PLS, true protein, true protein PLS, anhydrous lactose, and anhydrous lactose PLS. Repeatability and accuracy of fat, true protein, and anhydrous lactose determination using traditional filter models and PLS models were determined. Component predictions on externally homogenized milks (d(0.9) = about 1.0 μm) had excellent repeatability and accuracy on all components when pumped through both efficient and inefficient homogenizers. Variation in homogenizer performance on unhomogenized milks had a much larger impact on accuracy of component testing than on repeatability. The largest absolute impact was on fat measurements, producing a lower fat B test by about 0.16% at a d(0.9) of 3 μm. The fat A and fat PLS predictions were low by 0.08 and 0.07% fat, respectively, at a d(0.9) of 3 μm. Variation in homogenization had very little impact on true protein measured using the traditional filter approach but did have a larger impact on true protein predicted with a PLS model (low by 0.1% at a d(0.9) of 3 μm). Effects of variation in homogenization on anhydrous lactose predictions were small. The USDA Federal Milk Market laboratories use a d(0.9) value of 1.7 μm as a criteria to make the decision to replace the homogenizer in an IR milk analyzer. In our study, a d(0.9) of 1.8 μm produced a change in reading of < 0.04% fat and < 0.02% true protein. Both traditional filter and PLS mid-FTIR component prediction models were influenced by homogenizer performance.
关键词： component accuracy,homogenization,mid-FTIR
更新于2025-09-10 09:29:36
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Accuracy of 3D surface scanners for clinical torso and spinal deformity assessment
摘要： Externally visible deformities are cosmetic features of great concern for Adolescent Idiopathic Scoliosis (AIS) patients. Current assessment techniques for AIS do not fully encompass the external deformity. A non-invasive method capable of capturing superficial anatomy, such as 3D scanning, would enable better qualitative and quantitative evaluation of cosmesis. This study aimed to quantify the accuracy of commonly available scanners, in assessing posterior asymmetry in AIS. The technique of 3D surface deviation analysis was proposed as a suitable method for comparing the models created by each scanner. Eight plaster cast moulds manufactured to create braces for AIS patients were used as test samples. Four 3D scanners were selected: Solutionix RexScan CS + ; Artec Eva; Microsoft Kinect V1; iPhone with 123D Catch App. These scanners were selected from those available as representative of a range of scanning technologies. Each cast was scanned and 3D models created. A simulated rib hump measurement was obtained and the surface-to-surface deviations between the Solutionix scan and all other scans were determined. The Solutionix scanner is a metrology scanner of very high quality and so it was selected as the reference. Surface-to-surface deviations were calculated in the positive and negative directions separately to specifically identify size and volume inaccuracies created by the scans. Surface deviations showed excellent agreement between the Solutionix and the Eva with deviations of + 0.17 ± 0.17 mm (Eva regions larger) and ?0.20 ± 0.32 mm (Eva regions smaller) (mean ±SD). The Kinect showed lower agreement ( + 1.58 ± 1.50 mm and ?0.58 ± 0.58 mm). The iPhone scans were not able to be scaled to the correct size, so were excluded. Rib hump measurements with all scanners were within clinical measurement variability ( ±4.9 deg) of the known values. These commercially available 3D scanners are capable of imaging torso shape in 3D and deriving clinically relevant external deformity measures. The non-invasive 3D topographic information provided can be used to improve assessment of torso shape in spinal deformity patients.
关键词： Torso Deformity,3D Scanning,Scoliosis,Accuracy,Reproducibility of results,Surface topography,Surface Deviations
更新于2025-09-10 09:29:36