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An optimized photoelectron track reconstruction method for photoelectric X-ray polarimeters

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2018年 880卷 188-193页

作者： Kitaguchi, Takao Black, Kevin Enoto, Teruaki Fukazawa, Yasushi Hayato, Asami Hill, Joanne E. Iwakiri, Wataru B. Jahoda, Keith Kaaret, Philip McCurdy, Ross Mizuno, Tsunefumi Nakano, Toshio Tamagawa, Toru Hiroshima Univ Dept Phys Sci 1-3-1 Kagamiyama Higashihiroshima Hiroshima 7398526 Japan Hiroshima Univ Core Res Energet Universe 1-3-1Kagamiyama Higashihiroshima Hiroshima 7398526 Japan NASA Goddard Space Flight Ctr Greenbelt MD 20771 USA Rock Creek Sci 1400 East West Hwy Silver Spring MD 20910 USA Kyoto Univ Hakubi Ctr Adv Res Kyoto 6068302 Japan Hiroshima Univ Hiroshima Astrophys Sci Ctr 1-3-1 Kagamiyama Higashihiroshima Hiroshima 7398526 Japan RIKEN Nishina Ctr 2-1 Hirosawa Wako Saitama 3510198 Japan RIKEN MAXI Team 2-1 Hirosawa Wako Saitama 3510198 Japan Univ Iowa Iowa City IA 52242 USA

We present a data processing algorithm for angular reconstruction and event selection applied to 2-D photoelectron track images from X-ray polarimeters. The method reconstructs the initial emission angle of a photoelectron from the initial portion of the track, which is obtained by continuously cutting a track until the image moments or number of pixels fall below tunable thresholds. In addition, event selection which rejects round tracks quantified with eccentricity and circularity is performed so that polarimetry sensitivity considering a trade-off between the modulation factor and signal acceptance is maximized. The modulation factors with applying track selection are 26.6 +/- 0.4, 46.1 +/- 0.4, 62.3 +/- 0.4, and 61.8 +/- 0.3% at 2.7, 4.5, 6.4, and 8.0 keV, respectively, using the same data previously analyzed by Iwakiri et al. (2016), where the corresponding numbers are 26.9 +/- 0.4, 43.4 +/- 0.4, 54.4 +/- 0.3, and 59.1 +/- 0.3%. The method improves polarimeter sensitivity by 5%-10% at the high energy end of the band previously presented (Iwakiri et al. 2016). (c) 2017 Elsevier B.V. All rights reserved.

关键词： X-ray Polarimetry Photoelectric polarimeter Time projection chamber tracking algorithm

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Automated quantification and reconstruction of collagen matrix from 3D confocal datasets

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JOURNAL OF MICROSCOPY-OXFORD 2003年第2期210卷 158-165页

作者： Wu, J Rajwa, B Filmer, DL Hoffmann, CM Yuan, B Chiang, C Sturgis, J Robinson, JP Purdue Univ Dept Basic Med Sci W Lafayette IN 47907 USA Purdue Univ Dept Biol W Lafayette IN 47907 USA Purdue Univ Dept Comp Sci W Lafayette IN 47907 USA Purdue Univ Dept Biomed Engn W Lafayette IN 47907 USA Jagiellonian Univ Dept Biophys Jan Zurzycki Inst Mol Biol & Biotechnol PL-30387 Krakow Poland

The geometrical structure of fibrous extracellular matrix (ECM) impacts on its biological function. In this report, we demonstrate a new algorithm designed to extract quantitative structural information about individual collagen fibres (orientation, length and diameter) from 3D backscattered-light confocal images of collagen gels. The computed quantitative data allowed us to create surface-rendered 3D images of the investigated sample.

关键词： 3D reconstruction collagen fibre confocal microscopy ECM tracking algorithm

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Vision-based approach for predicting the probability of vehicle-pedestrian collisions at intersections

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IET INTELLIGENT TRANSPORT SYSTEMS 2020年第11期14卷 1447-1455页

作者： Zhou, Zhuping Peng, Yunlong Cai, Yifei Nanjing Univ Sci & Technol Xiaolingwei 200 Nanjing 210094 Peoples R China Southeast Univ Dongnandaxue 2 Nanjing 210096 Peoples R China

Road accidents impose serious problems on society. Possible collisions between vehicles and pedestrians must be detected before they occur so that a timely warning may be issued. By using the vision-based approach, this study presents an effective and efficient algorithm to estimate the vehicle-pedestrian collision probability at intersections. The real-time trajectories and movement parameters (position, speed, acceleration or direction) of vehicles and pedestrians are obtained based on state-of-the-art detection and tracking algorithm which include background subtraction method, faster regions with convolutional neural networks and optical flow method. To find the appropriate time to identify the latent collision risk for calculating the collision probability, this study defines the critical time based on different collision patterns of perception-reaction failure and evasive action failure. In addition, based on discrete acceleration and discrete angle, the authors get different extended trajectories which can include most situation when the conflict happened. Trajectories generation probability are given by the discrete choice probability model based on the Logit model to get the accurate collision probability. Real-world video data is implemented to demonstrate the approach. This proposed collision prediction method can provide some important results for designing the intelligent pedestrian signal timing schemes at intersections.

关键词： collision avoidance road traffic traffic engineering computing object detection probability road safety video signal processing road vehicles road accidents image sequences convolutional neural nets object tracking intelligent transportation systems pedestrians computer vision vision-based approach road accidents real-time trajectories tracking algorithm background subtraction convolutional neural networks optical flow collision risk trajectories generation probability discrete choice probability model collision prediction vehicle-pedestrian collision probability intelligent pedestrian signal timing intersections detection algorithm perception-reaction failure patterns evasive action failure patterns Logit model real-world video data

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Evaluation and Simulation of Sports Balance Training and Testing Equipment Based on Medical Video Image Analysis

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IEEE SENSORS JOURNAL 2020年第20期20卷 12005-12012页

作者： Zhang, Lei Jilin Normal Univ Coll Phys Educ Siping 136000 Peoples R China

Aiming at the shortcomings of video analysis system in the current process of balance force training, a new video analysis system for balance force training is proposed to analyze the test effect of balance force training. This paper evaluates and tests the function and utility of balance testing equipment by using the methods of sports training, sports biomechanics, mechanical design, sensors, video image analysis and computer-related research, combined with the latest research results of physical training at home and abroad. Firstly, several representative algorithms are selected in the frame difference method and background difference method. Then, these methods are tested according to the typical scene conditions, and the experimental results are used to compare and analyze the algorithms qualitatively and quantitatively, and the paper proposes the moving object detection and tracking based on GVF-Snake image model. The experimental results show that our proposed model has good detection effect compared with the background difference method based on Vibe algorithm, codebook model, Mixed Gauss model, adaptive Mixed Gauss model, median filter and adaptive background modeling. The system can accurately analyze the video and image information of sports training. The accuracy of key frame extraction is high, and the recall rate is high. It can be used to guide and evaluate balance force training. And the final evaluation results show the effectiveness of video image algorithm.

关键词： Training Sports Force Adaptation models Object detection Analytical models Target tracking Medical multimedia video image tracking algorithm testing equipment image processing

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Improved image processing-based crop detection using Kalman filtering and the Hungarian algorithm

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COMPUTERS AND ELECTRONICS IN AGRICULTURE 2018年 148卷 37-44页

作者： Hamuda, Esmael Mc Ginley, Brian Glavin, Martin Jones, Edward Natl Univ Ireland Univ Rd Galway Ireland

There is increasing interest in the use of image processing techniques for crop detection in intelligent weeding applications. An effective system for crop detection requires a high degree of adaptability to challenging circumstances such as different weather conditions and image capture conditions (vibration, variations in speed, etc.). To achieve the goal of a robust crop detection system, we have extended a previously-developed detection algorithm that is based on a combination of color-space and shape analysis, through the addition of object tracking. While the previous algorithm performed well in general, performance in sunny conditions was not as robust, opening up the possibility of improvement. The tracking algorithm consists of two steps. Firstly, we apply Kalman filtering to predict the new position of an object (a cauliflower plant in this case) in video sequences. Secondly, we use a data association algorithm (the Hungarian algorithm) to assign each detected crop that appears in each image to the correct crop trajectory. The recall matrix was used to evaluate the detection and tracking performance. With the help of tracking algorithm, detection failures were reduced, especially in sunny conditions, such that overall detection performance was raised from 97.28 to 99.3404%.

关键词： Image processing Smart weeding tracking algorithm Kalman filter Hungarian algorithm Crop detection

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An Enhanced Finite Element Macro-Model for the Realistic Simulation of Localized Cracks in Masonry Structures: A Large-Scale Application

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INTERNATIONAL JOURNAL OF ARCHITECTURAL HERITAGE 2018年第3期12卷 432-447页

作者： Saloustros, Savvas Pela, Luca Cervera, Miguel Roca, Pere Univ Politecn Catalunya UPC BarcelonaTech Dept Civil & Environm Engn Jordi Girona 1-3 Barcelona 08034 Spain Univ Politecn Catalunya UPC BarcelonaTech Int Ctr Numer Methods Engn CIMNE Barcelona Spain

Finite element macro-modeling approaches are widely used for the analysis of large-scale masonry structures. Despite their efficiency, they still face two important challenges: the realistic representation of damage and a reasonable independency of the numerical results to the used discretization. In this work, the classical smeared crack approach is enhanced with a crack-tracking algorithm, originating from the analysis of localized cracking in quasi-brittle materials. The proposed algorithm is for the first time applied to a large-scale wall exhibiting multiple shear and flexural cracking. Discussion covers structural aspects, as the response of the structure under different assumptions regarding the floor rigidity, but also numerical issues, commonly overlooked in the simulation of large structures, such the mesh-dependency of the numerical results.

关键词： Continuum modeling facades finite element analysis macro-modeling masonry mesh independency pushover analysis shear flexural cracks strain localization tracking algorithm

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Machine learning and dynamics based error-index method for the detection of monsoon onset vortex over the Arabian Sea: Climatology and composite structures

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QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 2023年第751期149卷 537-555页

作者： Sasanka, Talukdar Osuri, Krishna K. Niyogi, Dev Natl Inst Technol Rourkela Dept Earth & Atmospher Sci Rourkela India Univ Texas Austin Jackson Sch Geosci Dept Geol Sci Austin TX USA Univ Texas Austin Dept Civil Architectural & Environm Engn Austin TX USA Natl Inst Technol Rourkela Dept Earth & Atmospher Sci Rourkela 769008 Odisha India

Monsoon onset vortex (MOV) forms over the Arabian Sea near the northern flank of the low-level jet during the monsoon onset over Kerala (MOK). The study concerns the development and evaluation of an algorithm for detecting and tracking MOVs in regional/global analyses. The first step involves preparing the first-guess database of MOV locations based on geopotential height, surface and 850 hPa wind magnitude and circulation from ERA5 reanalysis for 1982-2020. Three different approaches: (a) error-index of MOV, (b) machine-learning (ML), and (c) combination of error-index and ML models, are employed to detect MOV. The error-index method, in which the detected vortex is compared with the idealized vortex, achieves an accuracy of 0.6 with a 0.95 true-positive-rate and 0.55 false-positive-rate. The best ML models can identify the MOVs in the training samples with maximum accuracy of 0.99. However, their accuracy is limited in tracking the MOVs continuously in the global analyses as they are not trained with wind circulation. The combined error-index and ML models could detect all the 27 observed MOVs in the ERA5 reanalysis with 5 false-positives. This approach is tested on IMDAA reanalysis, and the success rate is 0.79 with 6 false-positives. Temporal analyses show that similar to 95% of the MOVs occur during -10 to +20 days from MOK. Composite structures indicate that the MOVs exhibit higher sea-surface temperatures (> 0.3 ?) in the forward sector with 85% cloud cover in the left-rear sector. Rainfall of 4-5 mm center dot hr(-1) is seen in the left sector. Upper-level (700-200 hPa) warm core (> 3.5?) and lower-level (1000-700 hPa) cold-core (< 1?) is evident. The composite structures of MOVs are almost similar to that of monsoon depressions with higher asymmetry in the forward-rear sectors. This study may help explore future projections of MOV activity from climate models and its relationship with monsoon rainfall activity.

关键词： Arabian Sea composite structure machine learning monsoon onset vortex tracking algorithm

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Haptic Interaction for Mobile Assistive Robots

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2011年第11期60卷 3501-3509页

作者： Wang, Huanran Liu, Xiaoping P. Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

This paper presents an assistive robotic system, for which the user can interact with a mobile robot using a haptic interface, for senior and disabled people. The system consists of a nonholonomic PeopleBot mobile robot and a Phantom Omni haptic interface. Several technical problems related to the system are addressed and solved. Specifically, the backstepping technique is used, and a new tracking algorithm is developed for the robot to follow the user on a 2-D space. An adaptive fuzzy logic-based windowing method is proposed to solve the velocity estimation problem in the controller. A simple haptic rendering algorithm is designed to generate the haptic feedback based on the position error. Experiments show that the user can guide the movement of the robot quite easily and smoothly using the haptic interface.

关键词： Assistant robot haptics nonholonomic mobile robot tracking algorithm velocity estimation

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A fast-array Kalman filter solution to active noise control

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INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING 2005年第2-3期19卷 125-152页

作者： Fraanje, R Sayed, AH Verhaegen, M Doelman, NJ Delft Univ Technol Delft Ctr Syst & Control NL-2628 CD Delft Netherlands

A Kalman filter solution to active control and its fast-array implementation are provided. The adaptive control problem is formulated as a state-estimation problem and no interchanging of the adaptive filter and the secondary-path is imposed. Moreover, no estimate of the disturbance signal is needed, and we exploit the structure in the state-space matrices to derive a fast-array implementation. A minimum variance estimate of the controller coefficients and the secondary path state is obtained. When there is no uncertainty in the secondary path, state equivalence with the modified filtered-RLS algorithm is proven. Using exponential forgetting, the analysis shows that in the generation of the filtered reference signal in the modified filtered-RLS, exponential forgetting should be incorporated too. Simulations show the superiority in convergence of the fast-array Kalman algorithm over the fast-array modified filtered-RLS algorithm. Copyright (c) 2004 John Wiley & Sons, Ltd.

关键词： adaptive filters state-space array algorithm Kalman RLS tracking algorithm structured state-space model

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Electric Arc Length Control of Circular Seam in Welding Robot Based on Arc Voltage Sensing

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IEEE SENSORS JOURNAL 2022年第4期22卷 3326-3333页

作者： Lei, Ting Wu, Chaoqun Yu, Huiwen Wuhan Univ Technol Sch Mech & Elect Engn Wuhan 430070 Peoples R China

Arc length control plays an important role in improving welding quality, especially for tube-to-tubesheet welding with numerous and dense circular seams. The difficulty of arc length control lies not only in acquisition and processing of arc voltage signal, but also in designing reasonable tracking algorithm and control method. This paper proposes an arc voltage tracking system with a self-developed arc voltage module for orbiting robotic welding. A real-time arc voltage tracking algorithm based on direct current (DC) pulse square-wave is proposed, and a two-dimension and three-section fuzzy controller are also presented. The experimental results show that the maximum peak voltage (PV) decreases from 13.92 V (circular seam A) to 13.44 V (circular seam B). The surface morphology of circular seam B with arc voltage tracking is obviously superior than that of circular seam A without arc voltage tracking. The arc voltage tracking method proposed in this manuscript has an active influence on welding quality.

关键词： Welding Voltage control Voltage Sensors Tungsten Robots Electrodes Arc voltage tracking welding robot circular seam tracking algorithm

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