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The computation of dispersion relations for three-dimensional elastic waveguides using the Scaled Boundary Finite Element Method

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JOURNAL OF SOUND AND VIBRATION 2013年第15期332卷 3756-3771页

作者： Gravenkamp, Hauke Man, Hou Song, Chongmin Prager, Jens Fed Inst Mat Res & Testing D-12200 Berlin Germany Univ New S Wales Sch Civil & Environm Engn Sydney NSW 2052 Australia

In this paper, a numerical approach for the computation of dispersion relations for three-dimensional waveguides with arbitrary cross-section is proposed. The formulation is based on the Scaled Boundary Finite Element Method (SBFEM). It is an extension of the approach previously derived for plate structures. It is shown that the wavenumbers of guided waves in a waveguide can be obtained as the eigenvalues of the Z matrix, which is well known in the SBFEM. The Hamiltonian properties of this matrix are utilized to derive an efficient way to compute the group velocities of propagating waves as eigenvalue derivatives. The cross-section of the waveguide is discretized using higher-order spectral elements. It is discussed in detail how symmetry axes can be utilized to reduce computational costs. In order to sort the solutions at different frequencies, a mode-tracking algorithm is proposed, based on the Pade expansion. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： DISPERSION relations ELASTICITY WAVEGUIDES FINITE element method EIGENVALUES SYMMETRY (Physics) tracking algorithms

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Optimized Parallel Implementation of Extended Kalman Filter Using FPGA

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JOURNAL OF CIRCUITS SYSTEMS AND COMPUTERS 2018年第1期27卷

作者： Jarrah, Amin Al-Tamimi, Abdel-Karim Albashir, Tala Yarmouk Univ Dept Comp Engn Irbid 21163 Jordan

There are enormous numbers of applications that require the use of tracking algorithms to predict the future states of a system according to its previous accumulated states. Thus, many efficient techniques are widely adopted to estimate the future states of a system at every point in time to get the desired performance levels. Kalman filter is a popular and an efficient method for online estimations for linear measurements. Extended Kalman Filter (EKF), on the other hand, is more suited for nonlinear measurements. However, EKF algorithm is well known to be computationally intensive, and may not achieve the strict requirements of real time applications. This issue has motivated researchers to consider the use of parallel processing platforms such as Field Programmable Gate Arrays (FPGAs) and Graphic Processing Units (GPUs) to meet the real time requirements. This paper provides an optimized parallel architecture for EKF using FPGA. Our approach exploits many optimization and parallel techniques such as pipe lining, loop unrolling, dataflow, and inlining;and utilizes the inherently parallel architecture nature of FPGAs to accelerate the estimation process. Our experimental analyses show that our optimized implementation of EKF can achieve better results when compared to other implementations using GPU and multicore platforms. Moreover, higher performance levels can be achieved when operating on larger data sizes. This is due to our proposed optimization techniques that we have applied, and the exploited inherent parallelism among EKF operations.

关键词： tracking algorithms time series analysis data modeling data prediction extended Kalman filter field-programmable gate array (FPGA) high level synthesis tools (HLS Tools) parallel architecture optimization techniques

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Designing All-Pole Filters for High-Frequency Phase-Locked Loops

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MATHEMATICAL PROBLEMS IN ENGINEERING 2014年第1期2014卷 1-8页

作者： Pinheiro, Ricardo Bressan Piqueira, Jose Roberto C. Univ Sao Paulo Escola Politecn BR-05508900 Sao Paulo Brazil

Since the phase-locked loop (PLL) circuit was proposed in the 1930s, it is being used for a lot of situations when precise frequency and phase references are required. Among these applications, synchronous telecommunication networks experienced a strong development in order to support the explosive information traffic that the modern society demands. Consequently, bandwidth became a decisive parameter, implying higher and higher frequencies for the clock signals exchanged between the nodes of the networks and detected by PLLs. The necessity to improve clock precision that follows the bandwidth increase provoked the improvement of the filter component of the PLLs, avoiding instability and high-frequency components in the reference signals. Here, a technique of designing this kind of filter is presented, considering second-order filters, implying third-order PLLs. Simulations show that following this technique produces very fast tracking processes, enabling precise operation even for very high frequencies.

关键词： PHASE-locked loops TELECOMMUNICATION network management PARAMETER estimation SIGNAL processing tracking algorithms DECISION making

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A jump Markov particle filter for localization of moving terminals in multipath indoor scenarios

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2008年第8期56卷 3801-3809页

作者： Nicoli, M. Morelli, C. Rampa, V. Politecn Milan Dipartimento Elettron & Informaz I-20133 Milan Italy Nokia Siemens Networks SpA I-20060 Milan Italy Informat & Telecommun Engn Natl Res Council IEIIT Inst Elect I-20133 Milan Italy

This correspondence describes an efficient Bayesian framework for localization of moving terminals (MTs) in wideband wireless networks. In a previous paper, the authors have presented a grid-based technique, based on a hidden Markov model, that used the power delay profiles of the received signals to track the MT position. This grid-based Bayesian method has proved its efficacy in reducing localization errors in realistic indoor environments with multipath effects and mixed line-of-sight/non-line-of-sight (LOS/NLOS) conditions. However, the computational power and the memory storage requirements limit its use in practical wireless networks. To improve the computational efficiency, here we propose a jump-Markov particle-filter approach as an extension of the previous work;the LOS/NLOS sight process is the jumping feature that drives the MT motion dynamics, while the particle filter is used to track the MT position. Performance analyses, carried out for realistic multipath indoor environments, show that, with respect to the previous grid-based algorithm, this novel approach greatly reduces the tracking filter complexity still preserving the same localization accuracy. Simulation results prove also the robustness of the proposed method with respect to the uncertainty of sight statistics information.

关键词： Bayesian estimation hidden Markov model mobile positioning particle filter source localization tracking algorithms ultra-wideband communications

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Data association and geolocation for electronic support systems

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COMPUTERS & ELECTRICAL ENGINEERING 2012年第6期38卷 1745-1759页

作者： Kennedy, Hugh L. Scott, William Cook, Stephen C. Univ S Australia Def & Syst Inst DASI Mawson Lakes NSW Australia

Data association (DA) in highly sensitive electronic support (ES) systems is nontrivial when closely-spaced, low probability-of-intercept (LPI) emitters, in cluttered radio-frequency (RF) environments, are sought. A practical processing framework for these situations is presented in this paper. Joint probabilistic data association (JPDA) is used to handle the multitarget tracking (MTT) problem in frequency-augmented direction-of-arrival versus time coordinates (i.e. 'signal' space). It is shown that the JPDA update has a pleasantly simple form when processing a serial stream of time-stamped measurements. A Bayesian M-out-of-N track confidence model is derived using the beta distribution and used to 'integrate' automatic track management functions (i.e. JIPDA). A maximum-likelihood expectation-maximisation (ML-EM) algorithm is also derived and applied to perform bearing-only target-motion-analysis (TMA) in geographic coordinates for confirmed JIPDA tracks. The application of EM compensates for previous measurement-to-signal-track assignment errors and decreases the deleterious influence of spurious measurements, due to clutter or other emitters, without combinatorial complexity. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： LOW probability of intercept radar RADIO frequency tracking algorithms BETA distribution AUTOMATIC tracking MOTION analysis SIGNAL processing

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Development and evaluation of a seismic monitoring system for building interiors - Part II: Image data analysis and results

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2008年第2期57卷 345-354页

作者： Doerr, Kai-Uwe Kuester, Falko Nastase, Derek Hutchinson, Tara C. Univ Calif San Diego Calif Inst Telecommun & Informat Technol La Jolla CA 92093 USA Univ Calif Irvine Dept Elect Engn & Comp Sci Irvine CA 92697 USA Univ Calif San Diego Dept Struct Engn La Jolla CA 92093 USA Univ Calif San Diego Dept Comp Sci & Engn La Jolla CA 92093 USA

Previous experiences during earthquake events emphasize the need for new technologies for real-time monitoring and assessment of facilities with high-value nonstructural contents. Moreover, there is a substantial limitation in our ability to rapidly evaluate and identify potential hazard zones within a structure, exposing rescue workers, society, and the environment to unnecessary risks. A real-time image-based monitoring system, which is integrated with warning systems, would allow for improved channeling of resources and informed decision making for rescue workers and building owners. In recognition of these issues, in this paper, we describe a methodology for image-based tracking of seismically induced motions. The methodology includes the acquisition, calibration, and processing of image sequences to detect and track object features under seismic-event conditions. We address the issue of providing a reliable feature/object-detection and object-tracking methodology for an image sequence from a single camera view. In addition, we introduce an extension to the 2-D tracking approach by providing a 3-D feature tracking methodology when the camera array itself is affected by the seismic event. The methods presented are demonstrated using the data collected during the full-scale field vibration tests conducted on a vacant building that was damaged during the 1994 Northridge Earthquake (presented in a companion paper). We present experimental tracking results of the implemented algorithms for a variety of objects and discuss additional challenges that emerge when image-based systems are used under these extreme conditions.

关键词： data acquisition field monitoring image acquisition image processing seismic motions synchronization tracking algorithms

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A Fast and Efficient Clutter Rejection Algorithm for SAR Imagery

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2013年第4期49卷 2431-2439页

作者： Murthy, K. Ramachandra Biswas, Sambhunath Ghosh, Ashish Indian Stat Inst Machine Intelligence Unit Kolkata 700108 W Bengal India

A clutter rejection scheme is proposed for synthetic aperture radar (SAR) imagery based on two-stage two-dimensional principal component analysis (two-stage 2DPCA) followed by a bipolar eigenspace separation transformation (BEST) and a multilayer perceptron (MLP). For this, we have examined and analyzed four different algorithms. They are based on principal component analysis (PCA) both in one dimension (conventional PCA) and in two dimension with three different forms (2DPCA, alternative 2DPCA and two-stage 2DPCA), followed by BEST and MLP in each case. Feature extraction in different cases is carried out using respective PCA scheme. Each algorithm uses the BEST to further reduce dimensionality and enhance the generalization capability of the classifier. Classification between target chips and clutter chips is finally made through an MLP classifier. Experimental results on MSTAR public release database of SAR imagery are presented. Comparison of all the 2DPCA algorithms with an existing technique shows improvement both in performance and time. Moreover, all the 2DPCA algorithms compute eigenvectors and eigenvalues of image covariance matrix accurately and very efficiently with respect to time, and further reduces the effect of noise better than that in the case of PCA. Comparison reveals the fact that two-stage 2DPCA-based algorithm is the best (both in performance and time) between all algorithms.

关键词： SYNTHETIC aperture radar CLUTTER (Radar) tracking algorithms COVARIANCE matrices PRINCIPAL components analysis CLASSIFICATION

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Pipeline mapping with crawler-type in-pipe robot feature

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2023年第10期37卷 5015-5020页

作者： Park, Jungwan Yang, Hyunseok Hyundai Motor Co Inst Hwaseong Si 18280 Gyunggi Do South Korea Yonsei Univ Sch Mech Engn Seoul 80309 South Korea

In-pipe robots have become popular, allowing for non-destructive testing, visual inspection, and cleaning. In-pipe inspection is crucial for maintaining pipeline integrity, but it is difficult for humans to access pipelines and perform checks. This article focuses on an in-pipe robot navigating various pipeline structures and diameters. It consists of a center module, a tracking module, and an active pantograph mechanism. The hardware components, such as the motorized gear train, screw, pantograph mechanism, springs, track module, and angular sensors, are discussed. Additionally, the control methods employed by the robot, including normal force control and posture control, are explained. Finally, the tracking algorithms used to estimate the robot's position and direction within the pipeline are presented.

关键词： Control methods In-pipe inspection In-pipe robot Localization Normal force estimation Posture control tracking algorithms

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An Efficient MHT Implementation Using GRASP

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2014年第1期50卷 86-101页

作者： Ren, Xiaoyi Huang, Zhipei Sun, Shuyan Liu, Dongyan Wu, Jiankang Univ Chinese Acad Sci Beijing Peoples R China

The multiple hypothesis tracking (MHT) approach has been proven to be successful in multiple target tracking applications, however, its computational complexity remains a major hurdle to its practical implementation. This paper presents an efficient MHT implementation, referred to as "GRASP-MHT", which integrates a greedy randomized adaptive search procedure (GRASP) within a track-oriented MHT framework. The hypothesis generating problem arising in the MHT framework is formulated as a maximum weighted independent set problem, and a GRASP module is designed to generate multiple high-quality hypotheses. An extensive simulation study was carried out to compare the performance of the proposed GRASP-MHT against several well-known multitarget tracking algorithms, and multiple metrics were considered in order to make the performance evaluation more comprehensive. Experimental results indicate that, by efficiently generating and fusing multiple high-quality global hypotheses in the data association process, GRASP-MHT is able to achieve better overall tracking performance than other algorithms, especially in a closely-spaced multitarget scenario.

关键词： MULTIPLE target tracking COMPUTATIONAL complexity METAHEURISTIC algorithms COMBINATORIAL optimization tracking algorithms GREEDY algorithms SIMULATION methods & models

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Statistical analysis of long-lived mesoscale eddies in the Lofoten basin from satellite altimetry

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ADVANCES IN SPACE RESEARCH 2021年第2期68卷 364-377页

作者： Gordeeva, Svetlana Zinchenko, Vadim Koldunov, Aleksey Raj, Roshin P. Belonenko, Tatyana St Petersburg State Univ 7-9 Univ Skaya Nab St Petersburg 199034 Russia Russian State Hydrometeorol Univ 79 Voronezhskaya Ul St Petersburg 192007 Russia Russian Acad Sci Shirshov Inst Oceanol 36 Nahimovskiy Pr Moscow 117997 Russia Bjerknes Ctr Climate Res Nansen Environm & Remote Sensing Ctr Thormohlens Gate 47 N-5006 Bergen Norway

The paper presents a statistical analysis of long-lived detected mesoscale eddies in the Lofoten Basin (LB). An automated eddy iden-tification and tracking method is applied to the altimeter data during the time-period 1993-2017 to detect and track anticyclonic (ACEs) and cyclonic eddies (CEs) in the LB. Our analysis found that only one percent of the eddies detected are long-lived (eddy-life > 35 days). Even though only 1%, the detected 330 long-lived mesoscale eddies (CEs, 120;ACEs, 210) account for >11,550 daily individual eddy-observations. The lifetime, occurrence, generation sites, size, intensity, and drift of these long-lived eddies are quantified. The average drift speed of long-lived eddies is found to show a pronounced seasonal variation with a maximum from October to March. Long-lived eddies in the LB are further divided into four groups based on their region of generation and dissipation. Long-lived eddies gen-erated and dissipated outside the region of the Lofoten Vortex (group 2 eddies) are found to be the predominant type (CEs, 73.3%;ACEs, 69.5%). The eddies generated and dissipated in the region of the permanent Lofoten Vortex form the second dominant type (CEs, 14.3%;ACEs, 26.2%). Based on their lifetime, properties of the two predominant groups of eddies are examined in detail. The difference found in the temporal variability of the eddy characteristics of the two groups reflects their different genesis. The analysis revealed that the mesoscale eddies of group 2 have a longer life than eddies of group 1, and ACEs are more long-lived in comparison to CEs. The analysis also found three main areas of eddy generation in the frontal zone of the NwASC from where mesoscale eddies propagate to the north-west, forming three main corridors of trajectories. The study further provides evidence of long-lived cyclonic CEs surrounding the large quasi-permanent Lofoten Vortex (LV) and forming a shield around it. Small CEs located in two areas with centers at 69.5

关键词： Lofoten basin Mesoscale eddies Altimetry Automatic detection tracking algorithms Statistical analyses

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