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Developing a dynamic correction mechanism for aethalometer results of actual urban aerosols

ATMOSPHERIC RESEARCH 2021年 255卷 105529-105529页

作者： Zhang, Yuzhe Zhi, Guorui Jin, Wenjing Liu, Shijie Wang, Lei Li, Zhengying Shi, Rong Zhang, Peng Shu, Yun Hu, Jingnan Chinese Res Inst Environm Sci State Key Lab Environm Criteria & Risk Assessment Beijing 100012 Peoples R China Chinese Res Inst Environm Sci Inst Atmospher Environm Beijing 100012 Peoples R China China Natl Intellectual Property Adm Patent Examinat Cooperat Beijing Ctr Patent Off Beijing 100160 Peoples R China Qingdao Agr Univ Coll Mech & Elect Engn Qingdao 266109 Peoples R China

The aethalometer (AE) is usually used to monitor light-absorbing aerosols. However, since the AE must first collect particles on a filter tape and then detect the optical changes caused by the filter/particle system, the primary data reported by the AE are not in-situ absorption coefficients (binsitu), but light attenuation coefficients (bATN). The shadow effect, multiple scattering effect, and particle-scattering effect combine to generate artifacts. The intent of the present study was to develop a new correction methodology that could dynamically translate bATN into binsitu. A photoacoustic extinctiometer (PAX), which is usually accepted as a reference instrument for binsitu measurement, was concomitantly operated with an AE situated in wintertime Beijing, China. (i) During the observation period, the AE collected 303 consecutive quartz spots (n = 1, 2, 3..0.303) laden with particles. Each spot had a series of consecutive attenuation readings (ATNn,i(?), i = 1, 2, 3....) dependent on the ambient black carbon (BC) concentrations. Based on the 11-spot moving average of the compensation factors, fmoving,n(?), a dynamic shadow effect correction coefficient was devised (Eq. (9)). (ii) The bATNn,i for each of seven wavelengths could be calculated from ATNn,i(?), and the absorption ?ngstro?m exponent ?n,i was derived by considering the relationship between bATN,n,i(?) and ?. (iii) Meanwhile, the PAX continuously recorded binsitu,n,i. The composite scattering correction coefficient, CCn,i(?), could be calculated as Eq. (10). (iv) A liner relationship was discovered between the CC(?) and ?. At 880 nm, for example, the relationship was CC(?) = 1.79? + 2.63 (r2 = 0.90). (v) Apparently, the two key parameters, Rn,i[fmoving,n(?)] and CCn,i(?), are both derivable from the AE measurement data, which allows the translation from bATN,n,i to binsitu,n,i (Eq. (4)) from the AE alone, independent of other instruments. Applying the dynamic correction algorithm to the data from a differ

关键词： Aethalometer correction algorithm Photoacoustic In-situ absorption coefficient Wavelength dependence

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Wavelength Dispersion Analysis on Fiber-Optic Raman Distributed Temperature Sensor System

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Photonic Sensors 2013年第3期3卷 256-261页

作者： Weijie WANG Jun CHANG Guangping LV Zongliang WANG Zhi LIU Sha LUO Shuo JIANG Xiangzhi LIU Xiaohui LIU Yongning LIU School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application Shandong University Jinan 250100 P. R. China Institute of Automation Shandong Academy of Sciences Jinan 250014 China

The influence of the wavelength dispersion on the temperature accuracy of the Raman distributed temperature sensor system （RDTS） is analyzed in detail, and a simple correction algorithm is proposed to compensate the fiber position error caused by the wavelength dispersion. The principle of the proposed algorithm is described theoretically, and the correction on each point along the entire fiber is realized. Temperature simulation results validate that the temperature distortion is corrected and the temperature accuracy is effectively improved from ＋5 ℃ to ±1 ℃.

关键词： Distributed temperature sensor wavelength dispersion correction algorithm

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An Ionosphere Specification Technique Based on Data Ingestion algorithm and Empirical Orthogonal Function Analysis Method

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SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS 2018年第9期16卷 1410-1423页

作者： Aa, Ercha Ridley, Aaron Huang, Wengeng Zou, Shasha Liu, Siqing Coster, Anthea J. Zhang, Shunrong Chinese Acad Sci Natl Space Sci Ctr Beijing Peoples R China Univ Michigan Dept Climate & Space Sci & Engn Ann Arbor MI 48109 USA Univ Chinese Acar ly Sci Coll Earth & Planetary Sci Beijing Peoples R China MIT Haystack Observ 77 Massachusetts Ave Cambridge MA 02139 USA

A data ingestion method in reproducing ionospheric electron density and total electron content (TEC) was developed to incorporate TEC products from the Madrigal Database into the NeQuick 2 model. The method is based on retrieving an appropriate global distribution of effective ionization parameter (Az) to drive the NeQuick 2 model, which can be implemented through minimizing the difference between the measured and modeled TEC at each grid in the local time-modified dip latitude coordinates. The performance of this Madrigal TEC-driven-NeQuick 2 result is validated through the comparison with various International Global Navigation Satellite Systems Services global ionospheric maps and ionosonde data. The validation results show that a general accuracy improvement of 30-50% can be achieved after data ingestion. In addition, the empirical orthogonal function (EOF) analysis technique is used to construct a parameterized time-varying global Az model. The quick convergence of EOF decomposition makes it possible to use the first six EOF series to represent over 90% of the total variances. The intrinsic diurnal variation and spatial distribution in the original data set can be well reflected by the constructed EOF base functions. The associated EOF coefficients can be expressed as a set of linear functions of F-10.7 and Ap indices, combined with a series of trigonometric functions with annual/seasonal variation components. The NeQuick TEC driven by EOF-modeled Az shows 10-15% improvement in accuracy over the standard ionosphere correction algorithm in the Galileo navigation system. These preliminary results demonstrate the effectiveness of the combined data ingestion and EOF modeling technique in improving the specifications of ionospheric density variations.

关键词： Ionosphere Specification Technique Data Ingestion algorithm ionospheres correction algorithm Dataset TEC gene Ingestion EOF Orthogonal functions linear function Circular Functions

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The removal of artificially generated polarization in SHARP maps

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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC 2008年第869期120卷 805-813页

作者： Attard, Michael Houde, Martin Novak, Giles Vaillancourt, John E. Univ Western Ontario Dept Phys & Astron London ON N6A 3K7 Canada Northwestern Univ Dept Phys & Astron Evanston IL USA CALTECH Dept Phys & Astron Pasadena CA 91125 USA

We characterize the problem of artificial polarization for the Submillimeter High Angular Resolution Polarimeter (SHARP) through the use of simulated data and observations made at the Caltech Submillimeter Observatory (CSO). These erroneous, artificial polarization signals are introduced into the data through misalignments in the bolometer subarrays and by pointing drifts present during the data- taking procedure. An algorithm is outlined here to address this problem and correct for it, provided that one can measure the degree of the subarray misalignments and telescope pointing drifts. Tests involving simulated sources of Gaussian intensity profile indicate that the level of introduced artificial polarization is highly dependent on the angular size of the source. Despite this, the correction algorithm is effective at removing up to 60% of the artificial polarization during these tests. The analysis of Jupiter data taken in 2006 January and 2007 February indicates a mean polarization of 1: 44% +/- 0: 04% and 0: 95% +/- 0: 09%, respectively. The application of the correction algorithm yields mean reductions in the polarization of approximately 0.15% and 0.03% for the 2006 and 2007 data sets, respectively.

关键词： SUBMILLIMETER POLARIZATION MOLECULAR CLOUDS STAR-FORMATION POLARIMETRY correction algorithm angular size Polarization MOLECULAR CLOUDS STAR FORMATION Sharpening polarimetry Misalignment artificial

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algorithmic Translation correction Mechanisms: An End-to-end algorithmic Implementation of English-Chinese Machine Translation

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EAI ENDORSED TRANSACTIONS ON SCALABLE INFORMATION SYSTEMS 2023年第6期10卷

作者： Shi, Lei Shandong Univ Finance & Econ Sch Foreign Studies Jinan 250014 Shandong Peoples R China

INTRODUCTION: Machine translation is a modern natural language processing research field with important scientific and practical significance. In practice, the variation of languages, the limitation of semantic knowledge, and the lack of parallel language resources limit the development of machine ***: This paper aims to avoid duplicating neural networks during the learning process and improve the ability to generalize complex neural network machine translation models with limited ***: Textual material in the source language was studied, and a suitable textual material representation model was used to express complex, high-level, and abstract semantic information. Then, a more efficient neural network machine translation integration model was developed based on the control of written data and algorithms. RESULTS: Data mining must be applied to complex neural network machine translation systems based on transfer learning to standardize finite neural network ***: Neural network-based embedded machine translation systems based on migration training require a small number of labelled samples to improve the system's permeability. However, this adaptive migration learning region approach can easily lead to over-learning problems in neural network machine translation models, thus avoiding excessive correspondences during the learning process and improving the generalization ability of the translation model with limited neural network resources.

关键词： English translation corpus analysis semantic analysis correction algorithm

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Nonrandom quantization errors in timebases

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2001年第4期50卷 888-892页

作者： Stenbakken, GN Liu, D Starzyk, JA Waltrip, BC US Dept Commerce Natl Inst Stand & Technol Technol AdmDiv Elect Elect & Elect Engn Lab Gaithersburg MD 20878 USA Ohio Univ Sch Elect Engn & Comp Sci Athens OH 45701 USA

Timebase distortion causes nonlinear distortion of waveforms measured by sampling instruments. When such instruments are used to measure the rms amplitude of the sampled waveforms, such distortions result in errors in the measured root-mean squared (rms) values. This paper looks at the nature of the errors that result from nonrandom quantization errors in an instrument's timebase circuit. Simulations and measurements on a sampling voltmeter show that the errors in measured rms amplitude have a nonnormal probability distribution, such that the probability of large errors is much greater than would be expected from the usual quantization noise model. A novel timebase compensation method is proposed which makes the measured rms errors normally distributed and reduces their standard deviation by a factor of 25. This compensation method was applied to a sampling voltmeter and the improved accuracy was realized.

关键词： compensation correction algorithm quantization sampling timebase voltmeter

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Improved topographic correction for satellite imagery

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2001年第12期E84D卷 1820-1827页

作者： Chen, F Muramoto, K Kubo, M Kanazawa Univ Grad Sch Nat Sci & Technol Div Mat & Informat Sci Kanazawa Ishikawa 9208667 Japan

An improved algorithm is developed for correcting the topographic impact on satellite imagery, First, we analyze the topography induced distortion un satellite image. It is shown that the variation of aspect can cause the obvious different distortions in the remotely sensed image, and also effect the image illumination significantly. Because the illumination is the basis for topographic correction algorithms, we consider its variation in different smi-facing aspects in calculation a correction parameter and take it as a key element in the modified correction algorithm. Then, we apply the modified correction method on the actual Landsat Thematic Mapper satellite image. The topographic correction was done in different image data with different season and different solar angle. The corrected results show the effectiveness and accuracy using this approach.

关键词： satellite imagery mountainous region topographic factor correction algorithm

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Preliminary Study of the On-orbit Radiometric Traceability and Artifacts for the VIIRS Longwave Infrared Channels during Blackbody Temperature Changes 25

Preliminary Study of the On-orbit Radiometric Traceability a...

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Conference on Infrared Remote Sensing and Instrumentation XXV

作者： Cao, Changyong Wang, Wenhui Blonski, Slawomir Zhang, Bin NOAA Ctr Satellite Applicat & Res College Pk MD USA ERT Inc Laurel MD USA Univ Maryland CICS College Pk MD USA

ISBN: (纸本)9781510612648;9781510612631

The Visible Infrared Imaging Radiometer Suite (VIIRS) has been continuously observing the Earth with global coverage twice daily in the longwave infrared channels since January 20, 2012. These channels are primarily used for cloud detection, and for retrieving sea surface temperatures globally, as well as a number of other applications. The VIIRS sensor data records (SDR), aka level 1b data, have been shown to be accurate and stable at 0.1K level since the data reached validated maturity on March 18, 2014. However, during the scheduled quarterly warm-up/cool-down of the onboard blackbody calibration source, a calibration bias on the order of 0.1 K is introduced. The bias is further amplified by the sea surface temperature (SST) retrieval algorithm up to 0.3 K which causes an apparent spike in the SST product time series. Our previous study [1] reveals that this bias is likely caused by a fundamental assumption on the radiometric traceability of the VIIRS calibration equation, pertaining to the shape of the calibration curve. In this study, we further analyzed the equation and presented an improved correction algorithm known as Ltrace 2. This algorithm attempts to fundamentally reconcile the calibration curve shape assumption such that the calibration bias can be removed during the WUCD with better performance for all bands. Sample test results are presented to show the improvements using this algorithm.

关键词： S-NPP, VIIRS, warmup/cooldown, thermal emissivity bands longwave infrared sea surface temperature calibration anomaly correction algorithm

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AQUARIUS ENGINEERING PHASE ON-ORBIT T_A CALIBRATION

AQUARIUS ENGINEERING PHASE ON-ORBIT T<sub>A</sub> CALIBRATIO...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Mims, Amanda Ruf, Christopher Univ Michigan Ann Arbor MI 48109 USA

ISBN: (纸本)9781467311595

Aquarius is a passive microwave radiometer operating at L-band that is designed to measure ocean salinity. Launched in June 2011, the instrument has since been the subject of on-orbit calibration to evaluate its performance and characterize its stability. This study addresses external calibration methods, using observed antenna temperatures to characterize instrument behavior by computing the oceanic global average and vicarious cold statistics. Results indicate that a slow drift in antenna temperature is present throughout the mission, as well as shorter time scale variations. Implementation of a noise diode deflection ratio-based correction algorithm mitigates most of the short term variations but the slow drift remains present in both statistics. It is most apparent using the global average statistic. The drift can be largely removed by adjusting the instrument calibration to force agreement between observed and modeled global averages over long time intervals.

关键词： Aquarius Antenna Temperature microwave radiometers instrument calibration CALIBRATION METHODS Time intervals correction algorithm drift drift Drift TEST AUTHORIZATIONS TA tantalum ocean salinity

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Novel Motion Sensorless Control of Single Phase Brushless DC PM Motor Drive, with experiments

Novel Motion Sensorless Control of Single Phase Brushless DC...

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12th International Conference on Optimization of Electrical and Electronic Equipment

作者： Iepure, Liviu Ioan Boldea, Ion Andreescu, Gheorghe Daniel Iles, Dorin Blaabjerg, Frede Univ Politehn Timisoara Dept Elect Machines & Drives Parvan 2 RO-300223 Timisoara Romania Univ Politehn Timisoara Dept Automat & Appl Informat RO-300223 Timisoara Romania Ebm Papst St Georgen GmbH & Co Kg D-78112 St Georgen Romania Aalborg Univ Inst Energy Technol DK-9220 Aalborg Denmark

ISBN: (纸本)9781424470198

A motion sensorless control for single phase permanent magnet brushless d.c. (PM-BLDC) motor drives, based on flux integration and prior knowledge of the PM flux/position characteristic is proposed here and an adequate correction algorithm is adopted, in order to increase the robustness to noise and to reduce the sensitivity to accuracy of flux linkage estimation. An I-f strategy is used for starting, by prescribing a ramped reference frequency and a constant current, and then the seamless transition to close loop sensorless control takes place. The proposed control system is detailed and validated by simulation and experimental results.

关键词： motor drives Sensorless control control systems brushless fundamental frequencies Noise robustness Permanent magnet synchronous machines correction algorithm single phase flux linkage constant current Prior Learning

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