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Power modulated fiber-optic loop sensor: theoretical and experimental investigation
摘要： The present work is focused on discussing a power modulation based sensor created using a single mode optical fiber. The sensing principle allows making displacement measurements with high accuracy and in a large measurement range due to the presence of resonance peaks in the transmitted intensity. A theoretical model is developed for the Fiber-Optic Loop Sensor (FOLS) and is validated with experimental data. The results show close matching between theoretical predictions and experimental results, allowing the use of the sensor for displacement measurement.
关键词： experimental validation,Fiber optic loop sensor,deformation,theoretical model,power modulation
更新于2025-09-23 15:21:01
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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 - Cross Validation of GPM and Ground-Based Radar in Latin America and the Caribbean
摘要： A comparison between GPM Dual-frequency Precipitation Radar and ground-based radars located in South America and the Caribbean is presented. The analysis compares radar variables from both system during overpasses of GPM over ground-based radars in the region of interest. Attenuation and bias correction is performed to ground radar data. The results show the potential of GPM to calibrate and monitor weather radars and subsequently using them for ground validation in Latin America and the Caribbean.
关键词： Ground-based weather Radar,Precipitation Measurement,Remote Sensing,GPM,DPR,Ground Validation
更新于2025-09-23 15:21:01
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[Methods in Enzymology] Modern Approaches in Drug Discovery Volume 610 || A Guide to Run Affinity Screens Using Differential Scanning Fluorimetry and Surface Plasmon Resonance Assays
摘要： Over the past 30 years, drug discovery has evolved from a pure phenotypic approach to an integrated target-based strategy. The implementation of high-throughput biochemical and cellular assays has enabled the screening of large compound libraries which has become an important and often times the main source of new chemical matter that serve as starting point for medicinal chemistry efforts. In addition, biophysical methods measuring the physical interaction (affinity) between a low molecular weight ligand and a target protein became an integral part of hit validation/optimization to rule out false positives due to assay artifacts. Recent advances in throughput, robustness, and sensitivity of biophysical affinity screening methods have broadened their application in hit identification and validation such that they can now complement classical functional readouts. As a result, new target classes can be accessed that have not been amenable to functional assays. In this chapter, two affinity screening methods, differential scanning fluorimetry and surface plasmon resonance, which are broadly utilized in both academia and pharmaceutical industry are discussed in respect to their use in hit identification and validation. These methods exemplify how assays which differ in complexity, throughput, and information content can support the hit identification/validation process. This chapter focuses on the practical aspects and caveats of these techniques in order to enable the reader to establish their own affinity-based screens in both formats.
关键词： hit validation,drug discovery,surface plasmon resonance,affinity screening,differential scanning fluorimetry,biophysical methods,hit identification
更新于2025-09-23 15:21:01
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Measurement of the position and orientation of mechanical arm based on laser tracker
摘要： Fractional vegetation cover (FVC) is one of the most important criteria for surface vegetation status. This criterion corresponds to the complement of gap fraction unity at the nadir direction and accounts for the amount of horizontal vegetation distribution. This study aims to directly validate the accuracy of FVC products over crops at coarse resolutions (1 km) by employing ?eld measurements and high-resolution data. The study area was within an oasis in the Heihe Basin, Northwest China, where the Heihe Watershed Allied Telemetry Experimental Research was conducted. Reference FVC was generated through upscaling, which ?tted ?eld-measured data with spaceborne and airborne data to retrieve high-resolution FVC, and then high-resolution FVC was aggregated with a coarse scale. The fraction of green vegetation cover product (i.e., GEOV1 FVC) of SPOT/VEGETATION data taken during the GEOLAND2 project was compared with reference data. GEOV1 FVC was generally overestimated for crops in the study area compared with our estimates. Reference FVC exhibits a systematic uncertainty, and GEOV1 can overestimate FVC by up to 0.20. This ?nding indicates the necessity of reanalyzing and improving GEOV1 FVC over croplands.
关键词： product validation,Coarse resolution,fractional vegetation cover,SPOT/VEGETATION
更新于2025-09-23 15:19:57
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Assessment with Controlled In-Situ Data of the Dependence of L-Band Radiometry on Sea-Ice Thickness
摘要： The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) and the National Aeronautics and Space Administration (NASA) Soil Moisture Active Passive (SMAP) missions are providing brightness temperature measurements at 1.4 GHz (L-band) for about 10 and 4 years respectively. One of the new areas of geophysical exploitation of L-band radiometry is on thin (i.e., less than 1 m) Sea Ice Thickness (SIT), for which theoretical and empirical retrieval methods have been proposed. However, a comprehensive validation of SIT products has been hindered by the lack of suitable ground truth. The in-situ SIT datasets most commonly used for validation are affected by one important limitation: They are available mainly during late winter and spring months, when sea ice is fully developed and the thickness probability density function is wider than for autumn ice and less representative at the satellite spatial resolution. Using Upward Looking Sonar (ULS) data from the Woods Hole Oceanographic Institution (WHOI), acquired all year round, permits overcoming the mentioned limitation, thus improving the characterization of the L-band brightness temperature response to changes in thin SIT. State-of-the-art satellite SIT products and the Cumulative Freezing Degree Days (CFDD) model are veri?ed against the ULS ground truth. The results show that the L-band SIT can be meaningfully retrieved up to 0.6 m, although the signal starts to saturate at 0.3 m. In contrast, despite the simplicity of the CFDD model, its predicted SIT values correlate very well with the ULS in-situ data during the sea ice growth season. The comparison between the CFDD SIT and the current L-band SIT products shows that both the sea ice concentration and the season are fundamental factors in?uencing the quality of the thickness retrieval from L-band satellites.
关键词： sea ice thickness,retrieval model validation,upward looking sonar,Arctic,Soil Moisture Active Passive (SMAP),Soil Moisture and Ocean Salinity (SMOS) mission,L-band radiometry
更新于2025-09-23 15:19:57
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Machine learning-based mapping of micro-topographic earthquake-induced paleo Pulju moraines and liquefaction spreads from a digital elevation model acquired through laser scanning
摘要： The advent of public open source airborne laser scanning-produced digital elevation models (ALS DEM) has provided new perspectives on glacial geomorphology in the Nordic countries. Seismically-induced micro-topographic paleo-landforms can now be identified and mapped throughout the former Fennoscandian Ice Sheet, allowing spatial safety assessment for nuclear waste disposal. Automated machine learning techniques enable recognition of these fine-scale geomorphological features efficiently and in a consistent way nationwide. The current study focuses on automated recognition of paleo liquefaction spreads and Pulju moraines in northern Finland. Geomorphometric variables in different cell sizes were first derived from the 2 m ALS DEM by Gabor and principal curvature filtering to emphasize the elevational multi-scale texture of these paleo-seismic landforms. The Gabor textural variables were considered as a baseline method and the principal curvature features, including maximum and minimum curvature, were used because they have previously been proven critical in recognition of concave and convex elongated features. Both sets of raster variables were then turned into histogram-based features and input into a non-linear supervised multilayer perceptron early-stop committee which is a neural network classifier. The leave-one-out cross-validation performance results indicated principal curvature features to be highly successful with 94% accuracy. Principal curvatures provided a clear improvement to Gabor based features which provided significantly lower accuracies between 83?85%. The study demonstrates the high success of supervised neural network-based classification of ALS DEM data and derived textural features capturing the multi-scale nature of the micro-topographic liquefaction spreads and Pulju moraines. The approach could be utilized for time-efficient mapping of these paleo-seismic geomorphologies to complete paleo-seismic databases in formerly glaciated regions.
关键词： rotation invariant,histogram-based features,leave-one-out cross-validation,principal curvature,area invariant,multilayer perceptron,landforms,paleo-seismology,geomorphology,Gabor filter,Pulju moraine,liquefaction spreads
更新于2025-09-23 15:19:57
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A new spectrofluorimetric assay method for vandetanib in tablets, plasma and urine
摘要： Purpose: To develop a simple and sensitive spectrofluorimetric method for the determination of vandetanib (VDB) in tablets (containing 100 mg of the drug) and biological fluids (spiked human plasma and urine). Methods: The proposed method is based on examining the intrinsic fluorescence intensity of VDB in acetonitrile at 480 nm after excitation at 330 nm. Factors affecting fluorescence intensity of the cited drug (VDB), including the influence of pH, diluting solvent and time, were studied and optimized by one factor at a time approach. A calibration curve was constructed by plotting VDB fluorescence intensity at 480 nm versus VDB concentrations in ng mL-1. The method was validated according to the recommendations of International Conference on Harmonisation (ICH) for validation of the analytical procedures Results: The linearity range of the method was 20 – 600 ng mL-1, with limits of quantification (LOQ) and of detection (LOD) of 30.45 and 10.05 ng mL-1, respectively. The adopted method was applied successfully to the quantitation of VDB in pure powder form (100.90 ± 0.91 %), laboratory prepared tablets (97.86 ± 1.42 %), spiked human plasma (97.97 ± 2.36 %) and urine (97.59 ± 0.87 %). Comparison of the proposed method with that of liquid chromatography-tandem mass spectrometry showed that there was no significant difference (p < 0.05) between the two methods in terms of accuracy and precision. Conclusion: The proposed method is simple and highly sensitive and, consequently, can be applied to assay VDB in biological samples as well as in dosage form.
关键词： Human plasma,Dosage forms,Validation,Human urine,Assay,Spectrofluorimetry,Vandetanib
更新于2025-09-23 15:19:57
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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 - Sentinel-2 Level-L Radiometry Validation Using Vicarious Methods from Dimitri Database
摘要： Sentinel-2 is an Earth Observation optical mission developed and operated by the European Space Agency (ESA) in the frame of the Copernicus program of the European Commission. The mission consists on a MultiSpectral Instruments (MSI) on board a constellation of two satellites flying on the same orbit but phased at 180°: Sentinel-2A launched in June 2015 and Sentinel-2B launched in March 2017. It covers the Earth’s land surfaces and inland and coastal waters every five days at the equator under the same viewing conditions with high spatial resolution and wide field of view. Accurate radiometric calibration is key to the success of the mission; therefore, in-orbit calibration and validation activities are conducted within the Sentinel-2 Mission Performance Centre (MPC), including a consortium of Expert Support Laboratories (ESL). The Database of Imaging Multispectral Instrument and Tool for Radiometric Intercomparison (DIMITRI) is used to perform the vicarious validation of Level-1 products delivered to users. The aims of this validation are 1) to assess the quality of the data product at Level-1, 2) to monitor the evolution of the radiometry of both instruments and 3) to ensure that the products meet the mission requirement accuracy. Three vicarious methods are used, such as Rayleigh scattering, Desert Pseudo-Invariant Calibration Sites (PICS) and Sensor-to-Sensor inter-calibration methods. Although the results indicate good stability and performance of both sensors MSI-A/B, a slight discrepancy between them of ~1% over desert sites could be observed. Slight decrease of band B8A (865 nm) signal over Algeria-3 site has been detected since April 2017. This effect seems to be related to the impact of human and industry activities near the area. Radiometric performances and image quality of Sentinel-2 MSI-A/B level-1C products appear stable and meet the mission requirements.
关键词： Multispectral Instrument,validation,vicarious calibration methods,Remote sensing,Radiometry
更新于2025-09-19 17:15:36
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Characterisation of Functional-Trait Dynamics at High Spatial Resolution in a Mediterranean Forest from Sentinel-2 and Ground-Truth Data
摘要： The characterisation of functional-trait dynamics of vegetation from remotely sensed data complements the structural characterisation of ecosystems. In this study we characterised for the first time the spatial heterogeneity of the intra-annual dynamics of the fraction of absorbed photosynthetically active radiation (FAPAR) as a functional trait of the vegetation in Prades Mediterranean forest in Catalonia, Spain. FAPAR was derived from the Multispectral Instrument (MSI) on the Sentinel-2 satellite and validated by comparison with the ground measurements acquired in June 2017 at the annual peak of vegetation activity. The validation results showed that most of points were distributed along the 1:1 line, with no bias nor scattering: R2 = 0.93, p < 0.05; with a root mean square error of 0.03 FAPAR (4.3%). We classified the study area into nine vegetation groups with different dynamics of FAPAR using a methodology that is objective and repeatable over time. This functional classification based on the annual magnitude (FAPAR-M) and the seasonality (FAPAR-CV) from the data on one year (2016–2017) complements structural classifications. The internal heterogeneity of the FAPAR dynamics in each land-cover type is attributed to the environmental and to the specific species composition variability. A spatial autoregressive (SAR) model for the main type of land cover, evergreen holm oak forest (Quercus ilex), indicated that topographic aspect, slope, height, and the topographic aspect x slope interaction accounted for most of the spatial heterogeneity of the functional trait FAPAR-M, thus improving our understanding of the explanatory factors of the annual absorption of photosynthetically active radiation by the vegetation canopy for this ecosystem.
关键词： functional-trait dynamics,validation,Sentinel-2,mediterranean forest,field campaign,spatial heterogeneity
更新于2025-09-19 17:15:36
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Mathematical model development and optimal design of the horizontal all-glass evacuated tube solar collectors integrated with bottom mirror reflectors for solar energy harvesting
摘要： As one of the inexhaustible energy sources, solar energy as a means to provide space heating has been a public interest for decades. Many stand-alone solar thermal technologies have come into practice to replace the out-of-date systems. However, conventional solar thermal systems present two drawbacks: (1) unsteady solar sources can lead to insufficient heating in the winter, and (2) the solar collectors can become overheated in the summer. Therefore, this study proposes a conceptual design of an integrated solar harvesting unit that consists of the horizontal all-glass evacuated tube solar collectors and bottom mirror reflectors to overcome the above drawbacks to the largest extent possible. To accomplish this, a generic mathematical model of this design unit was developed, followed by the model validation process and optimal design analysis. For cities in the severe cold and cold climate zones of northern China, the bottom mirror reflectors can be regarded as solar energy collection boosters during the heating season, which can contribute solar energy ranging from 40% to 80% of the total collected solar energy depending on the inclined angles of the solar collectors and reflectors. In the summer, using such integrated unit with the solar collectors tilted at an obtuse angle, the absorbed solar radiation can be reduced by 20%, which is beneficial to overheating prevention.
关键词： Horizontal evacuated tube solar collector,Mathematical model,Optimal design,Bottom mirror reflector,Model validation
更新于2025-09-19 17:15:36