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Current Measurement With 3-D Coreless TMR Sensor Array for Inclined Conductor

IEEE SENSORS JOURNAL 2019年第16期19卷 6684-6690页

作者： Zhang, Huaiqing Li, Feifan Guo, Huan Yang, Zhiyuan Yu, Nian Chongqing Univ State Key Lab Transmiss Equipment & Syst Safety & Chongqing 400044 Peoples R China

Magnetic sensor arrays have been widely used in current measurement, due to their advantages of small size, low power consumption, high sensitivity, wide bandwidth, and large dynamic range. However, they all assume that the conductor is perpendicular to the plane of the sensor array and the error introduced by un-perpendicularity has not been eliminated until now. In this paper, a 3-D tunnel magnetoresistance (TMR) sensor array scheme with its correction algorithm for eccentric, inclined current-carrying conductor is proposed. The simulation comparison of the relative error caused by the inclined angle between 1-D, 2-D, and 3-D TMR sensor arrays is performed, where the maximum errors are 25%, 20.5%, and 139%. It is obvious that the correction algorithm of 3-D TMR sensor array can significantly improve the accuracy. Four 3-D TMR sensors are used in the experimental prototype to verify the accuracy and reliability of the correction algorithm.

关键词： Coreless current transducer TMR sensor un-perpendicularity circular sensor array correction algorithm

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A Systematic Method of Improving the Accuracy of an Information and Measuring System for Determining the Thermophysical Properties of Materials Under the Effect of Destabilizing Factors

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MEASUREMENT TECHNIQUES 2017年第5期60卷 473-480页

作者： Selivanova, Z. M. Khoan, T. A. Tambov State Tech Univ Tambov Russia

Mathematical models are proposed for evaluating the functional accuracy of an information and measuring system and the measurement channel under the influence of destabilizing factors. A comprehensive method of increasing the accuracy of the system is created that makes it possible, with permissible error, to measure the parameters of the thermophysical properties of materials: the coefficients of thermal conductivity and thermal diffusivity.

关键词： accuracy evaluation method mathematical model information and measuring system thermophysical properties of materials correction algorithm

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Bidirectional reflectance of coral growth-forms

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2016年第7期37卷 1553-1567页

作者： Miller, Indrie Forster, Bruce C. Laffan, Shawn W. Brander, Rob W. Univ New S Wales Sch Biol Earth & Environm Sci Sydney NSW 2052 Australia

In situ spectral reflectance measurements of substrates in a coral reef are often obtained by viewing a substrate at nadir. However, it is likely that off-nadir oblique viewing would show different spectral characteristics for most coral reef substrates and provide valuable information on structural properties. To understand the relationship between substrate structure and spectral response, this study examined the bidirectional reflectance distribution function (BRDF) of various growth-forms of hard corals and algae, as well as rock, rubble, and sand. BRDF measurements were collected on Heron Reef, the Great Barrier Reef, Australia, during the spring (October to November) of 2010, using a visible and near-infrared (VNIR) spectroradiometer attached to a goniometer. The measurements were made in the same five view zenith angles as the PROBA-1 Compact High Resolution Imaging Spectrometer (CHRIS) satellite (+55 degrees, +36 degrees, 0 degrees, -36 degrees, -55 degrees) in the solar principal plane (SPP). A correction algorithm was used to remove both water column and water surface effects. Uncorrected measurements for sand covered with benthic microalgae appeared to have BRDF effects, but when corrected showed an essentially diffuse spectral response. Corrected measurements for branching corals showed BRDF effects dependent on branch spacing, branch length, and colour. The results indicate that spectral reflectance does vary with view angle for complex substrates such as caespitose corals, macroalgae, and irregular beach-rock and to a lesser extent for digitate corals and rippled sand and that the morphology of the coral and the shadowing between branches determines total spectral response. It is concluded that BRDF information can provide additional discriminating features for some coral reef substrates, particularly in the wavelength range of 550-650 nm.

关键词： spectral reflectance plant habit look angles (electronics) corals branches Shadowing (Histology) Kelps spectral characteristic bidirectional reflectance coral reef Substrates fault breccia spectral sensitivity correction algorithm

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The introduced error associated with the contact-type detection for piston surface temperature in combustion engines using coaxial thermocouples and its eliminating algorithm

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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2022年 195卷

作者： Li, Guoliang Cheng, Xiaobei Meng, Huanru Deng, Tianlun Yang, Can Huazhong Univ Sci & Technol Sch Energy & Power Engn Wuhan 430074 Peoples R China

Piston surface temperature is critical original data in combustion engines for evaluating its heat load and studying the in-cylinder combustion and heat transfer, where a contact-type measurement method employing coaxial thermocouples is frequently used. But packaging coaxial thermocouples into a piston is bound to change the original temperature field of the piston to be tested, bringing about the introduced error, which is a key problem for the piston surface temperature detection. In this paper, a two-dimensional model of a coaxial thermocouple is established, based on which the introduced error is quantitatively evaluated firstly, followed by a discussion on the mechanisms of the introduced error next. Then three temperature correction methods are proposed aiming to reduce such serious introduced errors, and the correction effects are demonstrated for E, J, and K-type coaxial thermocouples with different film thicknesses. It is found that the introduced errors are remarkable for all the tested thermocouple types and hot junction depths, which are closely related to the corresponding impulse response deviations, more essentially, to the deviations between thermal product values (root rho ck) of the thermocouple material system and that of the prototype piston material. The introduced errors are effectively reduced by the three correction methods for most cases, among which Method-II behaves best, followed by Method-III, Method-I. Method-II can steadily reduce average relative error, an indicator of the introduced error, by more than two orders of magnitude to 0.09 parts per thousand around. (C) 2022 Elsevier Ltd. All rights reserved.

关键词： Introduced error Coaxial thermocouple Contact-type detection Piston surface temperature correction algorithm Internal combustion engine

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REMOVAL OF HARMONIC ARTIFACTS FROM SYNCHROTRON RADIATION CORONARY ANGIOGRAMS

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IEEE TRANSACTIONS ON NUCLEAR SCIENCE 1992年第5期39卷 1431-1437页

作者： ZEMAN, HD MOULIN, HR BROOKHAVEN NATL LAB NATL SYNCHROTRON LIGHT SOURCEUPTONNY 11973

Intravenous coronary angiograms of human subjects are now available from the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL). The high (4.4 T) magnetic field used under normal operation of the superconducting wiggler magnet on the X-17 beam line at NSLS yields a high critical energy (18.7 keV) and a large harmonic contamination of the desired X-ray flux at the K-edge of iodine (33.169 keV). The 66 and 99 keV contamination is a factor of 2.29 and 5.32 worse than for the human angiograms taken at the Stanford Synchrotron Radiation Laboratory (SSRL), where a critical energy of 13.0 keV obtained at beam line IV-2. This increased harmonic contamination produces severe artifacts in the images, especially where the patients ribs cross the left ventricle and aorta, which are filled with contrast agent. An algorithm has been developed which can remove these artifacts by solving the two simultaneous transcendental equations for the fractional X-ray transmissions through iodine and through water. The parameters are derived from measurements on a Lucite step-wedge phantom. Human angiograms taken at 4.4 T are shown before and after the correction algorithm is applied. These corrected angiograms are compared to uncorrected angiograms taken at 3.0 T.

关键词： National Synchrotron Light Source Angiogram iodine wiggler magnets normal operation correction algorithm synchrotron radiation beamline human subject Brookhaven National Laboratory Artifacts Aorta Left Ventricle

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Real-time recovery of the electron density from interferometric measurements affected by fringe jumps

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REVIEW OF SCIENTIFIC INSTRUMENTS 2006年第7期77卷 73505-1-73505-9-0页

作者： Murari, A. Zabeo, L. Boboc, A. Mazon, D. Riva, M. EURATOM ENEA Fus Consorzio RFX I-35127 Padua Italy UKAEA Euratom Fus Assoc Culham Sci Ctr Abingdon OX14 3DB Oxon England CEN Cadarache EURATOM Assoc F-13108 St Paul Les Durance France EURATOM ENEA Fus I-00044 Frascati Italy

Optical interferometers are normally used in magnetically confined plasmas to measure the refractive index of the plasma by comparing the phase shift variation between a reference and a probe laser beam, from which the line-integrated electron density can be derived. Unfortunately, interferometric measurements are affected by fringe jumps, which are basically the erroneous phase difference determination due to the loss of signals or a phase difference bigger than 2 pi. The multiple causes include the refraction, wavelength of the laser radiation used, sensitivity, and time resolution of the measurements. On the other hand, the plasma density has become an essential piece of information for many real-time control schemes, which can therefore be completely jeopardized by fringe jumps. To overcome this problem at JET two main approaches can be adopted. The first approach consists of performing a real-time correction of the affected chords, eliminating the spurious effect of the fringe jumps, and providing a corrected line integral of acceptable quality. This is done at JET by complex algorithms that have inputs of various interferometry and polarimetry measurements. A second approach can be adopted based on the observation that, for many real-time experiments, an approximate estimate of the density profile is sufficient. In JET, it was demonstrated that the density profile of the vast majority of configurations could be determined with sufficient accuracy by using only the line-integrated density profile provided by two chords;one external and one internal. The various solutions were tested and results compared in order to verify the most suitable one for the various plasma configurations and operational scenarios. A "general purpose" version of the correction algorithm was implemented and is now normally running during JET operation. (c) 2006 American Institute of Physics.

关键词： JET interference pattern correction algorithm phase difference Laser radiation Optical Interferometers Electron density clock recovery density profiles laser beams

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Rebinning-based algorithms for helical cone-beam CT

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PHYSICS IN MEDICINE AND BIOLOGY 2001年第11期46卷 2911-2937页

作者： Defrise, M Noo, F Kudo, H Free Univ Brussels Dept Nucl Med B-1050 Brussels Belgium Univ Liege Inst Montefiore B-4000 Liege Belgium Univ Tsukuba Inst Informat Sci & Elect Tsukuba Ibaraki 305 Japan

Several image reconstruction algorithms based on rebinning have been proposed recently for helical cone-beam CT. These algorithms separate the 3D reconstruction into a set of independent 2D reconstructions for a set of surfaces: planar or non-planar surfaces are defined and then reconstructed using 2D filtered backprojection from a 2D fan-beam or parallel-beam set of data estimated from the cone-beam (CB) measurements. The first part of this paper presents a unified derivation of rebinning algorithms for planar and nonplanar surfaces. An integral equation is derived for the surface allowing the best rebinning and an iterative algorithm converging to the solution of that equation is given. The second part presents an efficient method to correct the residual reconstruction artefacts observed with rebinning algorithms when the cone-anale is too large for the required accuracy. This correction algorithm involves a CB backprojection and the reconstruction time is slightly longer than for the zero-boundary (ZB) method.

关键词： algorithms seconds X-Ray Computed Tomography allowing Solutions 算法溶液 backprojection algorithms Reconstructive Surgical Procedures Planar Spiral Cone-Beam Computed Tomography correction algorithm nonplanarity X-Ray Computed Tomography three-dimensional displays

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Reduction of atmospheric and topographic effect on Landsat TM data for forest classification

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2008年第19期29卷 5623-5642页

作者： Huang, H. Gong, P. Clinton, N. Hui, F. Chinese Acad Sci State Key Lab Remote Sensing Sci Inst Remote Sensing Applicat Beijing 100101 Peoples R China Beijing Normal Univ Beijing 100101 Peoples R China Chinese Acad Sci Grad Sch Beijing 100049 Peoples R China Univ Calif Berkeley Div Ecosyst Sci Berkeley CA 94720 USA

The incident radiance in forested areas with rugged terrain varies greatly with the changes in solar elevation and azimuth, slope and aspect of the terrain, and the relative position of trees. The geotropic nature must be considered in the course of topographic correction. The Sun-Canopy-Sensor (SCS) model is introduced to substitute the cosine correction in a physical model. We used an atmospheric simulation code, MODTRAN, and a digital elevation model (DEM) to calculate the path radiance, downwards diffuse radiance and two-way transmittance of direct and diffuse light at different altitudes. Based on the atmospheric parameters derived above and the Lambertian assumption, surface reflectance in a forested area was retrieved from Landsat Thematic Mapper (TM) imagery using a revised physical model. Meanwhile, a smoothed DEM was used to assess the effect of noise on the DEM and misregistration between the DEM and the satellite imagery. Correlation analysis, spectral comparison between sunlit and shaded slopes and a support vector machine (SVM) classification were performed to assess the effect of the revised radiometric correction algorithm. Results indicate that the revised physical model with smoothed DEM is more adequate for forested terrain and more consistent spectra for similar vegetation under different illuminations can be obtained. Finally, higher classification accuracy of forested land can be achieved with the revised correction algorithm compared with the SCS correction and the original physical correction model.

关键词： TWIST1 gene landscapes Topographic Effects relative positioning physical models radiance terrains Noise effects thulium Forest wooded area misregistration correction algorithm reduction diffuse light

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TABLE BASED DECODING OF RATE ONE-HALF CONVOLUTIONAL-CODES

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IEEE TRANSACTIONS ON COMMUNICATIONS 1995年第2-4期43卷 681-686页

作者： DHOLAKIA, A VOUK, MA BITZER, DL Department of Computer Science North Carolina State University Raleigh NC USA

Table based error correction and decoding of rate one-half convolutional codes is described. A new class of fast-decodeable locally invertible convolutional coder based on a one-to-one mapping between information and encoded blocks of equal lengths is defined. The syndrome is used as an address to access a correction table which stores precomputed correction information, The correction table gen generation process is described and a specific table based correction algorithm is given. Performance of this scheme is analyzed and simulation results are presented.

关键词： correction algorithm error correction convolutional coding New classes DECODING Syndromes based correction table

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Calculation of TTC for multi-area power systems based on improved Ward-PV equivalents

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IET GENERATION TRANSMISSION & DISTRIBUTION 2017年第4期11卷 987-994页

作者： Xu, Shaoxiang Miao, Shihong Huazhong Univ Sci & Technol State Key Lab Adv Electromagnet Engn & Technol Wuhan Peoples R China

The total transfer capability (TTC) calculation is restricted by limited information exchanges in multi-area power systems. This study presents a multi-area TTC calculation method based on improved Ward-PV equivalents. In this study, only boundary bus voltages and predictors need to be exchanged between individual areas during the calculation. An improved Ward-PV external network equivalent is proposed as a network decomposition approach. The repeated power flow (RPF) algorithm with a self-adaptive predictor is implemented in each area's TTC calculation. Each area uses network equivalent models to calculate its own TTC via RPF. A modified distributed power flow method is employed as a correction algorithm to adjust power flow in all individual areas during the TTC calculation. The proposed method is verified on the IEEE 118-bus system with all operating limits and branch N - 1 contingencies considered. Results demonstrate the validity and the accuracy of this method.

关键词： OPERATING LIMIT multimachine power system correction algorithm Reverse Path Forwarding Power flow power systems

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