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parameter estimation for compound-Gaussian clutter with inverse-Gaussian texture

IET RADAR SONAR AND NAVIGATION 2017年第4期11卷 586-596页

作者： Mezache, Amar Bentoumi, Ahmed Sahed, Mohamed Univ Mohamed Boudiaf Msila Dept Elect Msila 28000 Algeria Univ Freres Mentouri Constantine Lab Signaux & Syst Commun Dept Elect Constantine 25010 Algeria

This study deals with the estimation problem of the inverse-Gaussian (IG)-compound-Gaussian (CG) distributed clutter parameters. Under the assumption of the absence of thermal noise, non-integer moments, log-moments and maximumlikelihood- based approaches are employed for model parameter estimation in the cases of single pulse and non-coherent integration of N pulses. The forms of the non-integer-order moments estimator and the [z log(z)] estimator are derived in terms of the Bessel and the exponential-integral functions, respectively. These formulas maintain monotonic nature over all values of the ratio between the shape parameter and the mean clutter power. For a single look data, the ML estimate combined with the mean clutter power is constructed in one dimension search for the shape parameter. By accommodating the mean square error metric, the estimation assessments are investigated via simulated and real data. Authors' results illustrate that the derived non-integer- order moments estimator is asymptotically efficient for the IG-CG distributed clutter parameters particularly in heavy tailed clutter situations.

关键词： maximum likelihood estimation Gaussian distribution radar clutter thermal noise Bessel functions inverse-Gaussian texture inverse-Gaussian-compound-Gaussian distributed clutter parameters IG-CG distributed clutter parameters thermal noise noninteger moments log-moments maximum-likelihood-based approach model parameter estimation noninteger-order moment estimator z log(z) estimator exponential-integral functions Bessel functions mean clutter power mean square error metric ML estimate

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Improvements in deterministic error modeling and calibration of inertial sensors and magnetometers

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SENSORS AND ACTUATORS A-PHYSICAL 2016年 247卷 522-538页

作者： Secer, Gorkem Barshan, Billur Bilkent Univ Dept Elect & Elect Engn TR-06800 Ankara Turkey

We consider the deterministic modeling, calibration, and model parameter estimation of two commonly employed inertial measurement units based on real test data acquired from a flight motion simulator. Each unit comprises three tri-axial devices: an accelerometer, a gyroscope, and a magnetometer. We perform the deterministic error modeling and calibration of accelerometers based on an improved measurement model, and the technique we propose for gyroscopes lowers costs by eliminating the need for additional sensors and relaxing the test bed requirement. We present an extended measurement model for magnetometers that reduces calibration errors by modeling orientation-dependent hard-iron errors in a gimbaled angular position-control machine. While we employ the model-based Levenberg-Marquardt optimization algorithm for the parameter estimation of accelerometers and magnetometers, we use a model-free evolutionary optimization algorithm (particle swarm optimization) for estimating the calibration parameters of gyroscopes. Errors are considerably reduced as a result of proper modeling and calibration. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Inertial sensors Accelerometer Gyroscope Magnetometer Deterministic error modeling Measurement model In-field calibration model parameter estimation Ellipsoid parameter estimation Levenberg-Marquardt algorithm Particle swarm optimization

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A sequence-based rate control framework for consistent quality real-time video

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2006年第1期16卷 56-71页

作者： Xie, B Zeng, WJ PacketVideo Corp San Diego CA 92121 USA Univ Missouri Dept Comp Sci Columbia MO 65211 USA

Most model-based rate control solutions have the generally questionable assumption that video sequence is stationary. In addition, they often suffer from the fundamental problem of,model parameter misestimation. In this paper, we propose a sequence-based frame-level bit allocation framework employing a rate-complexity model that has the capability of tracking the nonstationary characteristics in the video source without look-ahead encoding. In addition, a new nonlinear model parameter estimation approach is proposed to overcome the existing problems in previous model parameter estimation schemes where quantization parameter (QP) is determined to achieve the allocated bits for a frame. Furthermore, a general concept of bit allocation guarantee is discussed and its importance is highlighted. The proposed rate control solution can achieve smoother video quality with less quality flicker and motion jerkiness. Both a complete solution where requantization is employed to guarantee the achievement of the allocated bits, and a simplified solution without requantization are studied. Experimental results show that they both provide significantly better performance, in terms of average peak-signal-to-noise ratio and quality smoothness, than the MPEG-4 Annex L frame-level rate control solution.

关键词： bit allocation model parameter estimation rate control real-time encoding smooth quality stationarity assumption

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modelling the optical constants of organic thin films: impact of the choice of objective function

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JOURNAL OF OPTICS A-PURE AND APPLIED OPTICS 2000年第5期2卷 458-464页

作者： Djurisic, AB Fritz, T Leo, K Tech Univ Dresden Inst Appl Photophys D-01062 Dresden Germany

In this work, we model the optical constants of three organic materials using a modified Lorentz oscillator model. We have analysed the impact of the choice of the objective or merit function, which is employed for model parameter estimation, on the modelling of the optical constants. The objective function for model parameter determination should be chosen in such a manner that discrepancies between the experimental and calculated values for both parts of the index of refraction are minimized at the same time. We have found that the choice of objective function strongly influences the existence of multiple solutions. By combining a global optimization method, an appropriately chosen objective Function and a modified oscillator model, we obtain good agreement with the experimental data for three organic materials.

关键词： optical constants model parameter estimation

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Dependence of bacterial growth rate on dynamic temperature changes

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IET SYSTEMS BIOLOGY 2020年第2期14卷 68-74页

作者： Dey, Abhishek Bokka, Venkat Sen, Shaunak Indian Inst Technol Delhi Dept Elect Engn New Delhi 110016 India

Temperature is an important determinant of bacterial growth. While the dependence of bacterial growth on different temperatures has been well studied for many bacterial species, prediction of bacterial growth rate for dynamic temperature changes is relatively unclear. Here, the authors address this issue using a combination of experimental measurements of the growth, at the resolution of 5min, of Escherichia coli and mathematical models. They measure growth curves at different temperatures and estimate model parameters to predict bacterial growth profiles subject to dynamic temperature changes. They compared these predicted growth profiles for various step-like temperature changes with experimental measurements using the coefficient of determination and mean square error and based on this comparison, ranked the different growth models, finding that the generalised logistic growth model gave the smallest error. They note that as the maximum specific growth increases the duration of this growth predominantly decreases. These results provide a basis to compute the dependence of the growth rate parameter in biomolecular circuits on dynamic temperatures and may be useful for designing biomolecular circuits that are robust to temperature.

关键词： microorganisms temperature environmental factors mean square error methods parameter estimation bacterial growth rate dynamic temperature changes bacterial species bacterial growth profiles generalised logistic growth model escherichia coli model parameter estimation coefficient of determination mean square error environmental conditions

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Identification of partially known non-linear stochastic spatio-temporal dynamical systems by using a novel partially linear Kernel method

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IET CONTROL THEORY AND APPLICATIONS 2015年第1期9卷 21-33页

作者： Ning, Hanwen Jing, Xingjian Zhongnan Univ Econ & Law Sch Stat & Math Wuhan Hubei Peoples R China Hong Kong Polytech Univ Dept Mech Engn Kowloon Hong Kong Peoples R China Hong Kong Polytech Univ Shenzhen Res Inst Shenzhen Peoples R China

The identification of non-linear stochastic spatio-temporal dynamical systems given by stochastic partial differential equations is of great significance to engineering practice, since it can always provide useful insight into the mechanism and physical characteristics of the underlying dynamics. In this study, based on the difference method for stochastic partial differential equations, a novel state-space model named multi-input-multi-output extended partially linear model for stochastic spatio-temporal dynamical system is proposed. A new Reproducing Kernel Hilbert Space-based algorithm named extended partially linear least square ridge regression is thus particularly developed for the identification of the extended partially linear model. Compared with existing identification methods available for spatio-temporal dynamics, the advantages of the proposed identification method include that (i) it can make full use of the partially linear structural information of physical models, (ii) it can achieve more accurate estimation results for system non-linear dynamics and (iii) the resulting estimated model parameters have clear physical meaning or properties closely related to the underlying dynamical system. Moreover, the proposed extended partially linear model also provide a convenient state-space model for system analysis and design (e.g. controller or filter design) of the class of non-linear stochastic partial differential dynamical systems.

关键词： nonlinear dynamical systems stochastic systems spatiotemporal phenomena state-space methods MIMO systems partial differential equations regression analysis least mean squares methods nonlinear estimation control system synthesis Hilbert spaces nonlinear stochastic spatiotemporal dynamical system identification partially linear kernel method stochastic partial differential equations state-space model multiple input multiple output extended partially linear model kernel Hilbert space-based algorithm extended partially linear least square ridge regression model identification method partially linear structural information physical model model parameter estimation nonlinear system analysis nonlinear system design nonlinear stochastic partial differential dynamical system

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Characterization of Piezoelectric Energy Harvesters Using Frequency-Weighted Impedance Method

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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 2018年第10期65卷 7954-7962页

作者： Abasian, Alireza Tabesh, Ahmadreza Isfahan Univ Technol Dept Elect & Comp Engn Esfahan *** Iran

This paper presents a frequency-weighted impedance method for the characterization of piezoelectric bending beam energy harvesters. The method uses the frequency response of the beam to determine the beam model parameters. Existing methods often need to measure the beam tip deflection for the characterization of the parameters. This requires the accessibility of the tip and advanced measurement tools, such as a laser vibrometer. However, in the proposed method only the knowledge of the base acceleration is adequate to determine the electromechanical coupling coefficient of the beam. Furthermore, the rest of parameters including mechanical damping ratio can be determined based on a pure electrical test. The proposed method is useful for the characterization of all types of piezoelectric energy harvesters, particularly the vacuum-packed ones in which the tip of the beam is inaccessible. The validity of the method is experimentally verified using a test setup including a vacuum-packed piezoelectric energy harvester. The measured parameters of the beam are compared with the bulk material parameters showing that the proposed method can accurately estimate the model parameters without using the information of the tip deflection and with an error less than 4%.

关键词： Characterization coupling coefficient frequency-weighted impedance mechanical damping ratio model parameter estimation piezoelectric energy harvesters vibration

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modeling the optical constants of organic thin films: application to 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)

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OPTICS COMMUNICATIONS 2000年第1-4期183卷 123-132页

作者： Djurisic, AB Fritz, T Leo, K TU Dresden Inst ApAngew Photophys D-01062 Dresden Germany

We model the optical constants of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) using a modified Lorentz oscillator model and compare our results to the conventional Lorentz oscillator model. It is found that an adjustable broadening function incorporated in the modified Lorentz oscillator model should be used instead of a Lorentzian broadening function in the conventional oscillator model for modeling successfully the optical constants of organic materials. We attribute this to the assumption that each absorption peak is composed of a large number of individual transitions closely spaced in energy. (C) 2000 Published by Elsevier Science B.V.

关键词： optical constants model parameter estimation PTCDA

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Robust state estimation of the anaerobic digestion process for municipal organic waste using an unscented Kalman filter

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JOURNAL OF PROCESS CONTROL 2023年 121卷 50-59页

作者： Raeyatdoost, Niloofar Bongards, Michael Baeck, Thomas Wolf, Christian TH Koln Inst Automat & IT Steinmallerallee 1 D-51643 Gummersbach Germany Leiden Univ LIACS Niels Bohrweg 1 NL-2333 CA Leiden Netherlands

The stable and sustainable operation of anaerobic digestion (AD(1)) plants is crucial for their feasible long-term operation. Due to the high non-linearity of the AD process, the main contribution of this paper is to investigate the performance of a robust unscented Kalman filter (UKF) for dynamic process state estimation for the organic fraction of municipal solid waste (OFMSW2). A traditional UKF performance degrades in case of dynamical model uncertainties or the presence of unknown Gaussian and non-Gaussian noises. The utilized robust UKF proposed by Zhao and Mili (2019) addresses this issue by improving the accuracy of state estimation using the H-infinity filtering theory. The performance of the utilized estimator is tested for the case of uncertainties within the AD model and the substrate feed, as well as unknown Gaussian and non-Gaussian process and measurement noise. Results show that the developed robust UKF estimator achieves higher accuracy and presents higher robustness against uncertainties. Besides, the mathematical model considered for the simulation and the state estimator both rely on the extended version of the AD model No. 2 (E-AM2(3)) including a hydrolysis step. This model is a simplified AD model, which is a suitable choice for control and estimation purposes providing a reasonable trade-off between complexity and accuracy. In this paper, the developed E-AM2 model is adapted for the AD process of OFMSW. (c) 2022 Elsevier Ltd. All rights reserved.

关键词： State estimation H-infinity unscented Kalman filter Robustness Anaerobic digestion model parameter estimation Organic fraction of municipal solid waste

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Coaxial Integrated Tendon-Driven Actuator: Design, modeling, Control, and Performance Analysis

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IEEE ROBOTICS AND AUTOMATION LETTERS 2024年第11期9卷 10692-10699页

作者： Zhao, Di Wang, Xinbo Ren, Lei Wang, Kunyang Ren, Luquan Jilin Univ Key Lab Bion Engn Minist Educ Changchun 130022 Peoples R China

In this letter, a novel tendon-driven actuator is presented for anthropomimetic robots, mimicking the functionality of a spindle muscle. This actuator can contract and relax, and its tension output can be measured and controlled. The proposed actuator features an innovative space-saving co-axial winding mechanism and an integrated tension feedback sensor. Furthermore, the actuator incorporates an integrated controller and motor driving circuit, powered by a brushless direct current motor. A custom-designed sensor comprising four load cells is employed to measure tension in the tendon, and a closed-loop tension control method is proposed and validated. Tests, including evaluations of dynamic performance and transient response, are conducted on a custom-built test bench to verify the feasibility and efficacy of the proposed design. The test results indicate that the proposed actuator is capable of producing a maximum tendon tension of 300 N with a power density of 0.92 W/cm(3), while also facilitating the realization of backdrivability through closed-loop tension control.

关键词： Anthropomimetic robots tendon-driven actuators tendon-driven actuators model parameter estimation model parameter estimation tension control tension control backdrivable actuator backdrivable actuator backdrivable actuator

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