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Video pulse rate variability analysis in stationary and motion conditions

BIOMEDICAL ENGINEERING ONLINE 2018年第1期17卷 1-26页

作者： Melchor Rodriguez, Angel Ramos-Castro, J. Univ Politecn Cataluna Dept Elect Engn Grp Biomed & Elect Instrumentat Jordi Girona 1-3 ES-08034 Barcelona Spain

Background: In the last few years, some studies have measured heart rate (HR) or heart rate variability (HRV) parameters using a video camera. This technique focuses on the measurement of the small changes in skin colour caused by blood perfusion. To date, most of these works have obtained HRV parameters in stationary conditions, and there are practically no studies that obtain these parameters in motion scenarios and by conducting an in-depth statistical analysis. Methods: In this study, a video pulse rate variability (PRV) analysis is conducted by measuring the pulse-to-pulse (PP) intervals in stationary and motion conditions. Firstly, given the importance of the sampling rate in a PRV analysis and the low frame rate of commercial cameras, we carried out an analysis of two models to evaluate their performance in the measurements. We propose a selective tracking method using the Viola-Jones and KLT algorithms, with the aim of carrying out a robust video PRV analysis in stationary and motion conditions. Data and results of the proposed method are contrasted with those reported in the state of the art. Results: The webcam achieved better results in the performance analysis of video cameras. In stationary conditions, high correlation values were obtained in PRV parameters with results above 0.9. The PP time series achieved an RMSE (mean +/- standard deviation) of 19.45 +/- 5.52 ms (1.70 +/- 0.75 bpm). In the motion analysis, most of the PRV parameters also achieved good correlation results, but with lower values as regards stationary conditions. The PP time series presented an RMSE of 21.56 +/- 6.41 ms (1.79 +/- 0.63 bpm). Conclusions: The statistical analysis showed good agreement between the reference system and the proposed method. In stationary conditions, the results of PRV parameters were improved by our method in comparison with data reported in related works. An overall comparative analysis of PRV parameters in motion conditions was more limited due to the lac

关键词： Heart rate variability (HRV) Pulse rate variability (PRV) Imaging photoplethysmography (iPPG) Sampling rate Region of interest (ROI) tracking algorithm Stationary condition Motion scenario

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The decline in western disturbance activity over Northern India in recent decades

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CLIMATIC CHANGE 2023年第7期176卷 1-22页

作者： Javed, Aaquib Anshuman, Katyan Kumar, Pankaj Sachan, Disha Indian Inst Sci Educ & Res Bhopal Dept Earth & Environm Sci Bhopal By Pass Rd Bhopal 462066 India

Western disturbances (WDs) are upper-tropospheric synoptic-scale cyclonic storms that travel eastwards embedded in the subtropical westerly jet stream. They are of veritable significance to the sustenance of the population in the north and northwest regions of the Indian subcontinent and are often harbingers of extreme precipitation events during the boreal winter. This study utilizes a tracking algorithm with the upper-level vorticity field of the ERA5 reanalysis product to catalog events over the northern part of the Indian subcontinent for 39 WD seasons (Nov-Mar;1980-2019), including information about their trajectory and precipitation. The contribution of WDs to the region's total precipitation has been quantified comprehensively, enabling the proposition of a "core WD zone" and an intensity categorization of WDs affecting India. The core zone exhibits a decreasing trend for annual WD-associated precipitation despite the frequency of storms depicting no evident trend. The combined mean frequency of strong and extreme WDs declined by as much as similar to 43%, contrary to the mean occurrences of feeble and moderate WDs, which rose by similar to 11%. However, the mean seasonal precipitation volume decreased for all the categories, irrespective of the changes in their frequencies. The sharpest decline (similar to 49%) was observed for the most intense WDs (strong and extreme), primarily explaining the decreasing WD precipitation intensity across the core WD zone. The spatial distribution and evolution of various dynamical parameters reveal an inhibitive dynamic state of the atmosphere restricting the moisture advection capacity of WDs and the resultant decline in the associated precipitation over the core WD zone in recent decades.

关键词： Western disturbances Climate change tracking algorithm

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Adaptive modelling and long-range prediction of mobile fading channels

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IET COMMUNICATIONS 2010年第1期4卷 39-50页

作者： Heidari, A. Khandani, A. K. McAvoy, D. Univ Waterloo ECE Dept Coding & Signal Transmiss Lab Waterloo ON N2L 3G1 Canada Bell Canada Wireless Technol Strategy Mississauga ON Canada

A key element for many fading-compensation techniques is a (long-range) prediction tool for the fading channel. A linear approach, usually used to model the time evolution of the fading process, does not perform well for long-range prediction applications. An adaptive fading channel prediction algorithm using a sum-sinusoidal-based state-space approach is proposed. This algorithm utilises an improved adaptive Kalman estimator, comprising an acquisition mode and a tracking algorithm. Furthermore, for the sake of a lower computational complexity, an enhanced linear predictor for channel fading is proposed, including a multi-step AR predictor and the respective tracking algorithm. Comparing the two methods in our simulations show that the proposed Kalman-based algorithm can significantly outperform the linear method, for both stationary and non-stationary fading processes, and especially for long-range predictions. The performance and the self-recovering structure, as well as the reasonable computational complexity, makes the algorithm appealing for practical applications.

关键词： sum-sinusoidal-based state-space approach fading channels Kalman-based algorithm Filtering methods in signal processing channel fading long-range prediction computational complexity mobile fading channels adaptive modelling adaptive fading channel prediction algorithm Radio links and equipment tracking algorithm fading-compensation techniques wireless channels Kalman filters adaptive Kalman estimator multi-step AR predictor

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Critical Review on PV MPPT Techniques: Classical, Intelligent and Optimisation

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IET RENEWABLE POWER GENERATION 2020年第9期14卷 1433-1452页

作者： Bollipo, Ratnakar Babu Mikkili, Suresh Bonthagorla, Praveen Kumar Natl Inst Technol Goa Elect & Elect Engn Farmagudi Goa India

Maximum power extraction from the photovoltaic (PV) system plays a critical role in increasing efficiency during partial shading conditions (PSC's). The higher cost and low conversion efficiency of the PV panel necessitate the extraction of the maximum power point (MPP). So, a suitable maximum power point tracking (MPPT) technique to track the MPP is of high need, even under PSC's. This study gives an extensive review of 23 MPPT techniques present in literature along with recent publications on various hardware design methodologies. MPPT classification is done into three categories, i.e. Classical, Intelligent and Optimisation depending on the tracking algorithm utilised. During uniform insolation, classical methods are highly preferred as there is only one peak in theP-Vcurve. However, under PSC's, theP-Vcurve exhibits multiple peaks, one global MPP (GMPP) and the remaining are local MPPs. Hence, Intelligent and Optimisation techniques came into limelight to differentiate the GMPP out of all LMPPs. Every MPPT technique has its advantages and limits, but a streamlined MPPT is drafted in numerous parameters like sensors required, hardware implementation, tracking in PSC's, cost, tracking speed and tracking efficiency. This present study aimed to address the advancement in this area for further research.

关键词： photovoltaic power systems maximum power point trackers solar cell arrays optimisation PV MPPT techniques intelligent optimisation maximum power extraction photovoltaic system solar power generation partial shading conditions conversion efficiency solar PV panel PV system maximum power point tracking technique hardware design methodologies tracking algorithm PSC global MPP tracking efficiency GMPP P-V curve cost viability

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Fusion detection in time-lapse microscopy images: application to lipid droplets coalescence in plant seeds

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IFAC-PapersOnLine 2016年第26期49卷 239-244页

作者： Deslandes, François Laroche, Béatrice Trubuil, Alain MaIAGE INRA Université Paris-Saclay Jouy-en-Josas78350 France

Detecting fusion events between lipid droplets of Arabidopsis thaliana embryos is of significant interest to understand the role of lipid droplet proteins. Lipid droplet proteins, called oleosins, have been shown to influence the size of lipid droplets possibly by preventing coalescence. We propose to detect fusion events in timelapse microscopy images of several oleosin deficient A. thaliana embryos. To detect volume preserving fusion events in a dense environment, we propose a procedure based on particle tracking and statistical tests. Using synthetic data, we compare the performances of our method to heuristic decision rules adapted from tracking algorithms from the literature. © 2016

关键词： Image fusion Cytology Drops Heuristic algorithms Heuristic methods Image analysis Microscopic examination Plants (botany) Proteins Seed Arabidopsis thaliana Cell biology Event detection Heuristic decisions Multi target tracking Time lapse microscopy tracking algorithm Volume preserving

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tracking the Warhead Among Objects Separation from the Reentry Vehicle in a Clear Environment

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DEFENCE SCIENCE JOURNAL 2009年第2期59卷 113-125页

作者： Liu, Cheng-Yu Chen, Chi-Teh Lee Ming Inst Technol Dept Elect Engn Taipei Taiwan

Separating a reentry vehicle into warhead, main body, and debris is a conventional and efficient means of producing a huge decoy and increasing the kinetic energy of the warhead. This procedure Causes the radar to track the main body and debris, which radar cross section are large. and ignore the warhead, is the most important part of the reentry vehicle. The warhead is difficult to identify after separation using standard tracking criteria. This study presents a novel tracking algorithm by integrating input estimation and modified probabilistic data association filter to identity warhead among objects separation from the reentry vehicle in a clear environment. The proposed algorithm provides a good tracking capability tor the warhead ignoring the radar cross sec(ion. Simulation results reveal that the errors between the Updated and warhead trajectorics are reduced to a small interval in a short time. Therefore, the radar can generate it beam to illuminate the right area and keep tracking the warhead all the time. This algorithm is Worthy of further Study and application.

关键词： Input estimation probabilistic data assocition filter extended Kalman filter tracking algorithm trajectory estimation

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AN ANTENNA tracking METHOD FOR LAND-MOBILE SATELLITE-COMMUNICATIONS SYSTEM

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS 1995年第9期78卷 91-102页

作者： YAMAMOTO, S TANAKA, K WAKANA, H OHMORI, S MINIST POSTS & TELECOMMUN COMMUN RES LAB KOGANEI TOKYO 184 JAPAN

A new satellite-tracking method is proposed for a directional antenna installed on a car for L-band land-mobile satellite communication. This method uses both a fiber optic gyroscope (FOG) and a magnetic compass (MC) with an open-loop control algorithm, which compensates for the disadvantages of individual sensors. Since FOG can detect the angular velocity precisely but cannot detect the absolute azimuthal direction, this type of sensor has inherent errors due to accumulating the angular velocities necessary to obtain the azimuthal direction. Cumulative errors caused mainly by a disagreement between the FOG axis for measuring rotation and the vertical axis during turning curves can be compensated by MC. The disadvantage of MC is that errors due to magnetic disturbance are caused by magnetized bridges and trucks. In the proposed method, the occurrence of a magnetic disturbance is detected from a statistical analysis of MC acquired data and FOG is used to control the antenna direction when a car turns either right or left. According to an analysis of the three-dimensional motions of cars, it was determined that only azimuthal antenna tracking can provide the precise control required to obtain good tracking performance, even when using an L-band directional antenna with an antenna gain of approximately 13 dBi.

关键词： MOBILE SATELLITE COMMUNICATIONS ANTENNA tracking OPEN-LOOP CONTROL tracking algorithm FIBER OPTIC GYROSCOPE

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Exploring Blob Detection to Determine Atomic Column Positions and Intensities in Time-Resolved TEM Images with Ultra-Low Signal-to-Noise

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MICROSCOPY AND MICROANALYSIS 2022年第6期28卷 1917-1930页

作者： Manzorro, Ramon Xu, Yuchen Vincent, Joshua L. Rivera, Roberto Matteson, David S. Crozier, Peter A. Arizona State Univ Sch Engn Matter Transport & Energy Engn G Wing 301501 E Tyler Mall Tempe AZ 85287 USA Cornell Univ Dept Stat & Data Sci Ithaca NY USA Univ Puerto Rico Dept Math Sci Mayaguez PR USA

Spatially resolved in situ transmission electron microscopy (TEM), equipped with direct electron detection systems, is a suitable technique to record information about the atom-scale dynamics with millisecond temporal resolution from materials. However, characterizing dynamics or fluxional behavior requires processing short time exposure images which usually have severely degraded signal-to-noise ratios. The poor signal-to-noise associated with high temporal resolution makes it challenging to determine the position and intensity of atomic columns in materials undergoing structural dynamics. To address this challenge, we propose a noise-robust, processing approach based on blob detection, which has been previously established for identifying objects in images in the community of computer vision. In particular, a blob detection algorithm has been tailored to deal with noisy TEM image series from nanoparticle systems. In the presence of high noise content, our blob detection approach is demonstrated to outperform the results of other algorithms, enabling the determination of atomic column position and its intensity with a higher degree of precision.

关键词： atomic columns blob detection nanoparticles noisy time-resolved TEM tracking algorithm transmission electron microscopy

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Measurement of 3-D strain distribution by means of high-resolution X-ray CT image and tracking of microstructural features

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JOURNAL OF THE JAPAN INSTITUTE OF METALS 2007年第2期71卷 181-186页

作者： Kobayashi, Masakazu Toda, Hiroyuki Kawai, Yuji Kobayashi, Toshiro Uesugi, Kentaro Wilkinson, David S. Maire, Eric Aoki, Yoshimitsu Toyohashi Univ Technol Dept Prod Syst Engn Toyohashi Aichi 4418580 Japan McMaster Univ Dept Mat Sci & Engn Hamilton ON L8S 4L8 Canada Inst Natl Sci Appl F-69621 Villeurbanne France Shibaura Inst Technol Dept Informat Engn Tokyo 1358548 Japan

Measurement of interior strain distribution has been developed based on the synchrotron radiation computed tomography (SR-CT). In metal deformation, local strain distribution differs from macroscopic strain due to microstructural factors such as grains, grain boundaries, particles, pores, voids, and cracks. A model sample, which was made from a copper alloy strengthened with alumina, was prepared containing artificial pores. Tensile loading was applied to the sample step by step. High-resolution tomographic experiment was performed at the third-generation synchrotron radiation facility (SPring-8) in Japan. Gravity center position, volume and surface area in the pores, which were regarded as markers in a tracking procedure, were measured by 3-D digital image analysis in the SR-CT images. The markers before and after the deformation were provided for registration and macroscopic strain correction before the tracking procedure. The marker tracking was carried out by means of matching parameter that was described as functions of distance, volume and surface at markers. The ratio of success tracking was evaluated in order to clarify whether the tracking method developed in this study was reliable. The 3-D strain distribution was represented successfully by the tracking results. A combination of high-resolution SR-CT and tracking of microstructural features is effective to visualize interior strain distribution in materials in 3-D.

关键词： tracking algorithm interior strain local strain synchrotron radiation computer tomography three-dimensional observation three-dimensional image analysis

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Crop stem detection and tracking for precision hoeing using deep learning

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COMPUTERS AND ELECTRONICS IN AGRICULTURE 2022年 192卷

作者： Lac, Louis Da Costa, Jean-Pierre Donias, Marc Keresztes, Barna Bardet, Alain Univ Bordeaux IMS UMR 5218 F-33405 Talence France CNRS IMS UMR 5218 F-33405 Talence France CTIFL 28 Route Nebouts F-24130 Prigonrieux France

Developing alternatives to the chemical weeding process usually carried out in vegetable crop farming is necessary in order to reach a more sustainable agriculture. However, a precise mechanical weeding requires specific sensors and advanced computer vision algorithms to process crop and weed discrimination in real-time. In this paper we propose an algorithm able to detect, locate, and track the stem position of crops in images which is suitable for precision actions in vegetable fields such as mechanical hoeing within crop rows. The algorithm is twofold: (i) a deep neural network for object detection is first used to detect crop stems in individual RGB images and then (ii) an aggregation algorithm further refines the detections taking advantage of the temporal redundancy in consecutive frames. We evaluated the pipeline on images of maize and bean crops at an early stage of development, acquired in field conditions with a camera embedded in an experimental mechanical weeding system. We reported Fl-scores of respectively 94.74% and 93.82% with a location accuracy around 0.7 cm when compared with human annotation. Moreover, this pipeline can operate in real-time on an embedded computer consuming as little power as 30 W.

关键词： Precision agriculture Deep learning Neural network Object detection tracking algorithm

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