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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) - SIM Time Scale: 10 Years of Operation
摘要： The Inter-American Metrology System (SIM) is one of the world′s five major Regional Metrology Organizations (RMO′s). Starting in 2005, the SIM Time and Frequency Metrology Working Group (SIM TFWG) developed a time and frequency comparison network for the Americas (SIMTN). Currently 23 NMIs from SIM region participate on the SIMTN. Since 2008 the SIM TFWG is producing a time scale called SIM Time Scale (SIMT). SIMT is an averaged time scale computed in near real-time (every hour) from time difference data that the SIMTN produces and publishes every 10 minutes. In this paper, a SIMT evaluation based on data from August 2016 to January 2018 is presented.
关键词： international comparison,atomic clocks,Time Scales
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) - Establishment of RF Power Sensor Calibration at RCM - LIPI
摘要： Industries especially telecommunication and aviation industries require RF power sensor calibration. Research Center for Metrology (RCM) – LIPI as National Metrology Institute of Indonesia is responsible to establish RF power sensor calibration. The RF power sensor calibration system in the frequency range of 10 MHz to 18 GHz has been established at RCM - LIPI to build the measurement traceability of RF power sensor in Indonesia. Modification to the conventional direct comparison transfer method has generated more accurate measurement results. Currently, the calibration system is already used to calibrate RF power sensors from calibration laboratories and industries in Indonesia.
关键词： calibration,Accurate power,direct comparison transfer,traceability,RF power sensor
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) - Application of AC Quantum Voltmeter for Impedance Comparison
摘要： This paper describes the experimental application of the AC Quantum Voltmeter, developed at PTB, for impedance ratio measurements at voltages up to 5 V and frequencies up to 1 kHz. A calibrator Fluke 5720A and an Aivon DualDAC2 source is used interchanged as the AC voltage source, and as impedances two self-developed resistors of nominal values of 10 kΩ are used. The impedances are measured in a potentiometric way i.e. the AC Quantum Voltmeter measures the RMS voltages on each resistor in time sequence. Measurement results for different set-ups are given and described.
关键词： programmable Josephson voltage standard,AC Josephson metrology,impedance comparison,AC quantum voltmeter
更新于2025-09-10 09:29:36
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MEDIUM SIZE DUAL-AXIS SOLAR TRACKING SYSTEM WITH SUNLIGHT INTENSITY COMPARISON METHOD AND FUZZY LOGIC IMPLEMENTATION
摘要： Nowadays, renewable energy such as solar power has become important for electricity generation, and solar power systems have been installed in homes. Furthermore, solar tracking systems are being continuously improved by researchers around the world, who focus on achieving the best design and thus maximizing the efficiency of the solar power system. In this project, a fuzzy logic controller has been integrated and implemented in a medium-scale solar tracking system to achieve the best real-time orientation of a solar PV panel toward the sun. This project utilized dual-axis solar tracking with a fuzzy logic intelligent method. The hardware system consists of an Arduino UNO microcontroller as the main controller and Light Dependent Resistor (LDR) sensors for sensing the maximum incident intensity of solar irradiance. Initially, two power window motors (one for the horizontal axis and the other for the vertical axis) coordinate and alternately rotate to scan the position of the sun. Since the sun changes its position all the time, the LDR sensors detect its position at five-minute intervals through the level of incident solar irradiance intensity measured by them. The fuzzy logic controller helps the microcontroller to give the best inference concerning the direction to which the solar PV panel should rotate and the position in which it should stay. In conclusion, the solar tracking system delivers high efficiency of output power with a low power intake while it operates.
关键词： Dual-axis tracker,sunlight intensity comparison method,solar renewable energy,fuzzy logic
更新于2025-09-10 09:29:36
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Comparison of Neovascular Lesion Area Measurements From Different Swept-Source OCT Angiographic Scan Patterns in Age-Related Macular Degeneration
摘要： PURPOSE. We compared area measurements for the same neovascular lesions imaged using swept source optical coherence tomography angiography (SS-OCTA) and enlarging scan patterns. METHODS. Patients with neovascular age-related macular degeneration were imaged using a 100-kHz SS-OCTA instrument (PLEX Elite 9000). The scanning protocols included the 3 3 3, 6 3 6, 9 3 9, and 12 3 12 mm ?elds of view. Two groups were studied. Group 1 included small lesions contained within the 3 3 3 mm scan, and Group 2 included larger lesions that were fully contained within the 6 3 6 mm scan. RESULTS. A total of 30 eyes of 26 patients were enrolled in Group 1 and 30 eyes of 25 patients were enrolled in Group 2. In Group 1, the automated mean lesion area measurements were 1.11 (SD ? 0.78), 1.14 (SD ? 0.80), and 1.27 (SD ? 0.82) mm2 for the 3 3 3, 6 3 6, and 12 3 12 mm scans, respectively (ANOVA P < 0.001; post hoc comparisons, P ? 0.184, 3 3 3 vs. 6 3 6 mm; P < 0.001 for the other two pairs). In Group 2, the automated mean lesion area measurements were 5.43 (SD ? 2.56), 5.53 (SD ? 2.48), and 5.49 (SD ? 2.65) mm2 for the 6 3 6, 9 3 9, and 12 3 12 mm scans, respectively (ANOVA P ? 0.435; post-hoc comparisons, P ? 0.062, 6 3 6 vs. 9 3 9 mm; P ? 0.553, 6 3 6 vs. 12 3 12 mm; P ? 0.654, 9 3 9 vs. 12 3 12 mm). CONCLUSIONS. The similarity in lesion area measurements across different scan patterns suggests that SS-OCTA imaging can be used to follow quantitatively the enlargement of choroidal neovascularization as the disease progresses.
关键词： neovascular AMD,optical coherence tomography angiography,swept-source OCTA,quantified measurement comparison,choroidal neovascularization
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 - Cross-Comparison of Three SAR Soil Moisture Retrieval Algorithms Using Synthetic and Experimental Data
摘要： The objective of this study is to cross-compare three algorithms for retrieving surface soil moisture (SSM) from ESA’s Sentinel-1 (S-1) data. The context is provided by the large scientific and application interest in SSM products at high resolution and regional/continental scale that can be retrieved from S-1 data alone or in combination with other missions such as NASA/SMAP and ESA/SMOS. Of the three investigated algorithms, one inverts a scattering model exploiting a Bayesian approach, whereas the other two are change detection approaches. The cross-comparison is carried out by using both simulated and experimental data. Strengths and weaknesses of the three algorithms are identified and discussed.
关键词： Algorithm comparison,Soil Moisture,Sentinel-1,Validation
更新于2025-09-09 09:28:46
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The OH<sup>*</sup>(3&ndash;1) layer emission altitude cannot be determined unambiguously from temperature comparison with lidars
摘要： I investigate the nightly mean emission height and width of the OH?(3–1) layer by comparing nightly mean temperatures measured by the ground–based spectrometer GRIPS9 and the Nalidar at ALOMAR. The dataset contains 42 coincident measurements between November 2010 and February 2014, when GRIPS9 was in operation at the ALOMAR observatory (69.3?N, 16.0?E) in northern Norway. To closely resemble the mean temperature measured by GRIPS9, I weighted each nightly mean temperature profile measured by the lidar using Gaussian distributions with 40 different centre altitudes and 40 different full widths at half maximum. In principle, one can thus determine the altitude and width of the OH?(3–1) layer by finding the minimum temperature difference between the two instruments. On most nights, several combinations of centre altitude and width yield a temperature difference of ±2 K. The generally assumed altitude of 87 km and width of 8 km is never an unambiguous, good solution for any of the measurements. Even for a fixed width of ～8.4 km, one can sometimes find several centre altitudes that yield equally good temperature agreement. Weighted temperatures measured by lidar are not suitable to determine unambiguously the emission height and width of an OH? layer. If the OH?(3–1) rotational temperature is used as a proxy for the temperature at an altitude of 87 km with a width of 8.4 km, this proxy is representative to within ±16 K.
关键词： emission altitude,OH?(3–1) layer,Nalidar,ALOMAR,lidar,GRIPS9,temperature comparison
更新于2025-09-04 15:30:14
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Total Global Solar Radiation Estimation with Relative Humidity and Air Temperature Extremes in Ireland and Holland
摘要： Solar radiation is the earth’s primary energy source for all biochemical and physical activities. Accurate knowledge of the solar radiation is important in engineering applications. This study aimed to calibrate some of the existing models in the literature for estimating daily total global solar radiation parameter using available measuring records (maximum and minimum air temperatures) and new models were developed based on maximum and minimum air temperatures, relative humidity and relative humidity extremes. Applicability of the Hargreaves model, Allen model, Bristow-Campbell model and Chen model were evaluated for computing the daily total solar global radiation, the geographical and meteorological data of Irish and Dutch cities were used. Meteorological data were taken from Royal Netherlands Meteorological Institute and Irish Meteorological Service. The models were compared on the basis of error tests which were mean percentage error (MPE), mean bias error (MBE), root mean square error (RMSE) and Nash-Sutcliffe equation (NSE). And, monthly MPE errors were given for each model. This study proposed new estimation models which were based on daily average relative humidity, relative humidity extremes and temperature extremes. Error analyses were applied to these models and results were given in the study.
关键词： Holland,solar radiation,model validation,temperature,daily total global solar radiation,relative humidity,model comparison,Ireland,meteorological models
更新于2025-09-04 15:30:14
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[IEEE 2018 4th International Conference on Science and Technology (ICST) - Yogyakarta (2018.8.7-2018.8.8)] 2018 4th International Conference on Science and Technology (ICST) - Multi-Sensors Remote Sensing for Mapping and Monitoring Canals on Tropical Peatland
摘要： An assessment of multi-sensor remote sensing images for observation of canals on peatland in Indonesia has been carried out. Canals construction on peatlands is closely related to forest degradation and deforestation, and hence mapping and monitoring of these canals is essential for in conservation and restoration of degraded peatland Indonesia. Over million hectares of tropical peatland across the country and rapid land dynamic change, this task requires advance tools with capabilities to cover large area and detect change in near real time. With limitation possessed by each of remote sensing image, an effective and efficient mapping and monitoring system should be established by integration of these multi-sensors remote sensing. This paper presents evaluation of these images and how their performance fit into the system.
关键词： mapping and monitoring canals,images comparison,multi-sensors remote sensing,peatland degradation,tropical peatland
更新于2025-09-04 15:30:14
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Determination of optimized frequency and frequency ratio values from over-determined sets of clock comparison data
摘要： We summarize a recently developed method for analyzing over-determined sets of clock frequency comparison data to derive optimized values for the frequency ratios between each of the contributing standards. This least-squares adjustment procedure, based on the approach used by CODATA to derive a self-consistent set of values for the fundamental physical constants, is used to deduce optimized frequency and frequency ratio values from the international body of clock comparison data available in September 2015.
关键词： frequency ratios,optical atomic clocks,least-squares adjustment,clock frequency comparison
更新于2025-09-04 15:30:14