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oe1(光电查) - 科学论文

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出版时间
  • 2015
研究主题
  • Calibration process of OSL detectors
  • Iodine-131
  • OSL-BeO
  • Dosimetry of staff and patients
  • Optically Stimulated Luminescence (OSL)
应用领域
机构单位
  • Akdeniz University
316 条数据
?? 中文（中国） ▾

  • [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) - Calibration of Current Shunt Standards in the Megahertz Region

    摘要： Beyond 1 A (from 2 A to 100 A typically) standard current shunts are currently calibrated in magnitude up to 100 kHz and in phase angle up to 200 kHz. For such high current levels and above these frequencies the existing traceable measurement methods are not able to characterize current shunts and cannot provide the phase and magnitude of impedance simultaneously. This paper briefly describes a new broadband method for measuring current shunt standards beyond 1 A in the megahertz region and presents experimental results demonstrating the efficiency of this approach.

    关键词： Calibration method,current measurement,VNA,uncertainty,current shunt,phase angle,wideband measurements,ac-dc difference

    更新于2025-09-10 09:29:36

  • A novel algorithm for second-order calibration of three-way data in fluorescence assays of multiple breast cancer-related DNAs

    摘要： Fluorescent probes have been valuable tools for bioanalytical multiplex assays. However, as a common phenomenon in multiplex fluorescence assays, spectral overlap usually leads to difficulty in spectral analysis for multiple analytes. Although multiway calibrations have provided mathematic approaches for complex spectral analysis, it remains a grand challenge for these methods in practical applications because of the problems such as prior rank estimation. Herein, we report a novel second-order calibration algorithm of alternating residual trilinearization (ART) for the decomposition of complex spectra generated from multiplex fluorescence assays. By alternating iterative convergence to the spectral profiles of each component in convergence process, ART enables automatic rank estimation for second-order calibration, thus able to avoid the risk of chemical meaningless fitting of component spectra. Combined with fluorescence excitation-emission matrix (EEM) spectroscopy, the performance of ART has been demonstrated by a simulated example and an analytical experiment performed using molecular beacons (MBs) for the simultaneous assay of three breast cancer related DNA targets. The results revealed that the proposed algorithm is capable of automatic estimating the number of underlying components during its convergence process to produce acceptable performance in spectral profile resolution and concentration estimation. Compared with other existing iterative trilinear decomposition strategies such as parallel factor analysis (PARAFAC) requiring a prior rank estimation, the proposed ART therefore provides a robust second-order calibration strategy for complex spectral analysis in multiplex fluorescence assays.

    关键词： Alternating residual trilinearization (ART),Molecular beacon,Fluorescence spectroscopy,Second-order calibration,Multiplex assay

    更新于2025-09-10 09:29:36

  • PLANAR PHASED ARRAY CALIBRATION BASED ON NEAR-FIELD MEASUREMENT SYSTEM

    摘要： Matrix method for phased array calibration is an excitation reconstruction method by solving the linear equations based on the linear relationship between the measured near-field data and element excitations. In this paper, we propose a modified matrix method, in which the phased array model is simplified, to measure the element excitations of planar phased array. Our method reduces measurement time greatly at the cost of introducing some calibration errors. The introduced calibration errors can be minimized with the array excitation strategy proposed in this paper. Experimental results validate the effectiveness of our methods in calibrating planar phased arrays.

    关键词： excitation reconstruction,near-field measurement,phased array calibration,matrix method

    更新于2025-09-10 09:29:36

  • Linewidth calibration using a metrological atomic force microscope with a tip-tilting mechanism

    摘要： The linewidth or critical dimension (CD) of a nanoscale line pattern is calibrated using a metrological atomic force microscope with a tip-tilting mechanism (tilting-mAFM). The tilting tip allows scanning of the line pattern’s vertical sidewalls. The tilting-mAFM performs two measurements on each side of the line pattern, and two datasets are stitched together to reconstruct the complete shape of the line pattern. Further, CD is measured based on this pattern. A linewidth standard with a subnanometer-scale uncertainty was used as a target sample to verify this CD calibration procedure. The calibrated CD using tilting-mAFM was 111.2 nm with an expanded uncertainty of 1.0 nm, which was the smallest uncertainty that was observed among the CD measurements that were reported using the tilting-AFM instruments. Further, the difference of this CD value from the reference CD was only 0.2 nm. The results reveal that tilting-mAFM can be used for CD metrology with a single-nanometer accuracy.

    关键词： metrological AFM,critical dimension (CD),calibration,tilting-AFM,nanometrology,linewidth

    更新于2025-09-10 09:29:36

  • Quantifying several adulterants of notoginseng powder by near-infrared spectroscopy and multivariate calibration

    摘要： The authentication of traditional Chinese medicine (TCM) is critically important for public-health and economic terms. Notoginseng, a classical TCM of high economic and medical value, could be easily adulterated with sophora flavescens powder (SFP), corn flour (CF) or other analogues of low-grade (ALG) because of their similar tastes, appearances and much lower cost. The main objective of this study was to evaluate the feasibility of applying of near-infrared (NIR) spectroscopy and multivariate calibration for identifying and quantifying several common adulterants in notoginseng powder. Two datasets were prepared for experiment. The competitive adaptive reweighted sampling (CARS) was used to select informative variables. Two different schemes were used for sample set partition. Model population analysis (MPA) was made. The results showed that, the constructed partial least squares (PLS) model using a reduced set of variables from CARS can provide superior performance to the full-spectrum PLS model. Also, the sample set partition is very of great importance. It seems that the combination of NIR spectroscopy, CARS and PLS is feasible to quantify common adulterants in notoginseng powder.

    关键词： calibration,Notoginseng,adulteration,near-infrared

    更新于2025-09-10 09:29:36

  • [American Society of Agricultural and Biological Engineers 2018 Detroit, Michigan July 29 - August 1, 2018 - ()] 2018 Detroit, Michigan July 29 - August 1, 2018 - <i>RPi Macro Camera: An Inexpensive and Handheld Camera Based on the Raspberry Pi Computer for Plant Phenotype Studies</i>

    摘要： The technological and scientific advancement in the field of agriculture has opened a new era for design and development of modern devices for plant phenotype studies. To take advantage of recent advances in mobile technology, we built a low-cost point-and-shoot prototype camera called RPi Macro Camera, RMC, using for photographing macro images of plant. RMC consists of a Raspberry Pi computer equipped with adjustable CMOS camera modules easily to removed and replaced, as well as a lithium battery, and a 5-inch touchscreen liquid crystal display. The package size of the RMC measured about 130 x 100 x 100 mm3 and it weighed less than 600 grams. The total cost of the components was less than USD 150. The inexpensive camera, RMC, was tested on serial sections of wheat straw in different growth stages dyed with safranin O-fast green supported over microslides. Our prototype camera was direct photography with samples in conventional environment with power supplied from battery. The camera was able to obtain good-quality images for statistical analysis on red and green intensity associated with simple programming including image segmentation and color calibration. With modest improvements and further image processing algorithm, RMC is expected to be useful for a variety of plant phenotype studies

    关键词： plant phenotype,color calibration,RMC (RPi Macro Camera),low cost photography,image segmentation

    更新于2025-09-10 09:29:36

  • From the Fermi-Dirac Distribution to PD curves

    摘要： In machine learning applications, and in credit risk modeling in particular, model performance is usually measured by using CAP and ROC curves. The purpose of this paper is to use the statistics of the CAP curve to provide a new method for credit PD curves calibration that is not based on arbitrary choices as the ones used in the industry. We map CAP curves to a ball-box problem and we use statistical physics techniques to compute the statistics of the CAP curve from which we derive the shape of PD curves. This approach leads to a new type of shape for PD curves that have not been considered in the literature yet, namely the Fermi-Dirac function which is a two parameter function depending on the target default rate of the portfolio and the target accuracy ratio of the scoring model. We show that this type of PD curve shape is likely to outperform the logistic PD curve that practitioners often use. We suggest that practitioners should stop using logistic PD curves and should adopt the Fermi-Dirac function to improve the accuracy of their credit risk measurement.

    关键词： machine learning,logistic function,PD calibration,Scoring,credit risk,Fermi-Dirac

    更新于2025-09-10 09:29:36

  • Calibrated optical time transfer of UTC(k) for supervision of telecom networks

    摘要： We report on the evaluation of the performance of optical time transfer links connecting a facility of Deutsche Telekom in Bremen with the Physikalisch-Technische Bundesanstalt in Braunschweig. In the current configuration three links have been established, two via a hub in Hannover and one using an independent alternate route. They are equipped with electronically stabilized fiber optic time and frequency transfer systems and parallel operation is maintained since December 2016. A novel method of link calibration, composed of two steps (one performed in the laboratory and the second one in the field), to accurately determine the influence of fiber chromatic dispersion is discussed in detail, and a thorough analysis of the uncertainty budget is given. We show that the time transfer performance achieved is difficult to characterize based on measurements with time interval counters that are the standard equipment in timing laboratories and in the telecommunications sector. In our experiments, values of TDEV at the low ps-level at averaging times between 104 to 106 seconds have been achieved. The uncertainty of time transfer (including all kinds of delays) is of the order of 50 ps in a cascade of links. The results obtained show that such a kind of link is capable to deliver signals to a remote end with an instability being at least two orders of magnitude below the current requirements included in relevant Recommendations of the International Telecommunication Union – Telecommunication Sector (ITU-T). Moreover, the current implementation would allow primary Cs fountain clocks to be compared at the level of their performance, that is characterized by an uncertainty at the low 10-16 level and a frequency instability of the same order of magnitude at one day averaging.

    关键词： propagation delay calibration,frequency transfer,telecom network supervision,time transfer,uncertainty budget,fiber optic

    更新于2025-09-10 09:29:36

  • Review: Measurement Techniques for Intraocular Pressure

    摘要： The literature on intra-ocular pressure dynamics is reviewed, including tonometer design and calibration, the influence of corneal-scleral mechanics, and scleral rigidity factors. Drugs that influence the outflow facility of the trabecular meshwork (TM) are discussed. Transmural pressure drop across the lamina cribosa (LC) is an important parameter, in terms of quantifying potential glaucoma damage to the optic nerve.

    关键词： Glaucoma,Ocular rigidity,Calibration,Intraocular pressure,Tonometer

    更新于2025-09-10 09:29:36

  • Assessment of Sun photometer Langley calibration at the high-elevation sites Mauna Loa and Iza?a

    摘要： The aim of this paper is to analyze the suitability of the high-mountain stations Mauna Loa and Iza?a for Langley plot calibration of Sun photometers. Thus the aerosol optical depth (AOD) characteristics and seasonality, as well as the cloudiness, have been investigated in order to provide a robust estimation of the calibration uncertainty as well as the number of days that are suitable for Langley calibrations. The data used for the investigations belong to the AERONET and GAW-PFR networks, which maintain reference Sun photometers at these stations with long measurement records: 22 years at Mauna Loa and 15 years at Iza?a. In terms of clear-sky and stable aerosol conditions, Mauna Loa (3397 m a.s.l.) exhibits on average 377 Langley plots (243 morning and 134 afternoon) per year suitable for Langley plot calibration, whereas Iza?a (2373 m a.s.l.) shows 343 Langley plots (187 morning and 155 afternoon) per year. The background AOD (500 nm) values, on days that are favorable for Langley calibrations, are in the range 0.01–0.02 throughout the year, with well-defined seasonality that exhibits a spring maximum at both stations plus a slight summer increase at Iza?a. The statistical analysis of the long-term determination of extraterrestrial signals yields to a calibration uncertainty of ～ 0.25–0.5 %, this uncertainty being smaller in the visible and near-infrared wavelengths and larger in the ultraviolet wavelengths. This is due to atmospheric variability produced by changes in several factors, mainly the AOD. The uncertainty cannot be reduced based only on quality criteria of individual Langley plots and averaging over several days is shown to reduce the uncertainty to the needed levels for reference Sun photometers.

    关键词： Sun photometers,aerosol optical depth,Langley calibration,Iza?a,Mauna Loa

    更新于2025-09-10 09:29:36