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26th Saint Petersburg International Conference on Integrated Navigation Systems (ICINS)

作者： Kramlikh, A. V. Lomaka, I. A. Shafran, S. V. Samara Univ Samara Russia

ISBN: (纸本)9785919950653

The paper describes a radio compass based on GNSS technology, an algorithm for processing GNSS information, an algorithm for calculating the coordinates of a unit vector of the longitudinal axis of a nanosatellite, and an approach that allows an estimation of the inertial characteristics of a nanosatellite. The estimation of the influence of the baseline length on the accuracy of determining the orientation angles is given. The results of the statistical study of the error determination of the nanosatellite inertial parameters using a radio compass are presented.

关键词： nanosatellite GPS GLONASS radio compass navigation reciever inertial chatacteristics identification algorithm

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AN INNOVATION STATE SPACE APPROACH FOR TIME SERIES FORECASTING

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Journal of Time Series Analysis 1993年第6期14卷 589-601页

作者： Libert, Gaëtan Wang, Liang Liu, Bao Faculté Polytechnique de Mons Belgium Tianjin University China

Abstract. An innovation state space modelling approach is presented in which the structures and parameters of a model are determined by an identification algorithm proposed by Tse and Weinert (IEEE Trans. Automat. Contr. 120 (1975), 603–13) and the singular value decomposition technique. This approach is applied to two typical data series to illustrate its use, and its forecasting accuracy is compared with other time series approaches. Copyright © 1993, Wiley Blackwell. All rights reserved

关键词： identification algorithm Innovation state space model singular value decomposition time series forecasting

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identification of critical roads in urban transportation network based on GPS trajectory data

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PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 2019年 535卷 122337-000页

作者： Feng, Huifang Bai, Fengshan Xu, Youji Northwest Normal Univ Coll Math & Stat Lanzhou 730070 Gansu Peoples R China

This study proposes a novel identification method of critical roads based on the combination of GPS trajectory data and directed weighted complex network. First, with both the static road network topology and the dynamic traffic flow characteristics taken into account simultaneously, a new spatial temporal model of urban transportation, namely a directed weighted complex network, is proposed. Then, combining the structure of road network with the strength influence of traffic between adjacent roads, a mixed influence-based identification algorithm of critical roads is proposed. Finally, we analyze taxi-GPS trajectory data collected in Lanzhou, China. We perform a comprehensive analysis to visualize the spatial-temporal changes of taxi services, critical roads, and critical intersections. Moreover, the correlation coefficient has been used to evaluate the performance of the identification algorithm of critical roads. The results show that the new identification algorithm is more effective and practical than traditional congestion index analysis. Our investigation should be helpful in urban traffic management and the residential choice of alternative routes. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Urban transportation network Critical roads Directed weighted complex network identification algorithm GPS trajectory data

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A parameter identification scheme for the orthotropic Poly6 yield function satisfying the convexity condition

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EUROPEAN JOURNAL OF MECHANICS A-SOLIDS 2022年 92卷 1页

作者： Soare, Stefan C. Tech Univ Cluj Napoca C Daicoviciu 15 Cluj Napoca 40020 Romania

The yield surface is the boundary of the elastic domain of a material and determines, via the normality rule, the direction of plastic deformation. Therefore, an accurate model of the yield surface of a material is crucial for the numerical simulation of its deformation processes. In addition, the yield surface must be convex in order to ensure a one-to-one relationship between the plastic strain rate and a corresponding stress state. In this context, homogeneous polynomial functions, in their most general form, have been shown to have a wide modeling range. However, it is also well known that these functions are not convex by default and hence the material parameters (the polynomial coefficients) must be subject to additional convexity constraints. Here we show that Poly6, the sixth order polynomial, features complete decoupling between pure shear and uniaxial traction. This allows us to devise a simple least squares optimization scheme based on biaxial and uniaxial test data, and an additional set of convexity control points which leads to a fast and explicit identification algorithm (Supporting code at https://***/stefanSCS/Poly6).

关键词： Metals Plasticity Yield function Polynomials Convexity identification algorithm

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On Recovery of a Non-Negative Relaxation Spectrum Model from the Stress Relaxation Test Data

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POLYMERS 2023年第16期15卷 3464-3464页

作者： Stankiewicz, Anna Bojanowska, Monika Drozd, Pawel Univ Life Sci Lublin Fac Prod Engn Dept Technol Fundamentals PL-20612 Lublin Poland Univ Life Sci Lublin Fac Food Sci & Biotechnol Dept Chem PL-20950 Lublin Poland

The relaxation spectra, from which other material functions used to describe mechanical properties of materials can be uniquely determined, are important for modeling the rheological properties of polymers used in chemistry, food technology, medicine, cosmetics, and many other industries. The spectrum, being not directly accessible by measurement, is recovered from relaxation stress or oscillatory shear data. Only a few models and identification methods take into account the non-negativity of the real spectra. In this paper, the problem of recovery of non-negative definite relaxation spectra from discrete-time noise-corrupted measurements of relaxation modulus obtained in the stress relaxation test is considered. A new hierarchical identification scheme is developed, being applicable both for relaxation time and frequency spectra. Finite-dimensional parametric classes of models are assumed for the relaxation spectra, described by a finite series of power-exponential and square-exponential basis functions. The related models of relaxation modulus are given by compact analytical formula, described by the products of power of time and the modified Bessel functions of the second kind for the time spectrum, and by recurrence formulas based on products of power of time and complementary error functions for frequency spectrum. The basis functions are non-negative. In result, the identification task was reduced to a finite-dimensional linear-quadratic problem with non-negative unknown model parameters. To stabilize the solution, an additional smoothing constraint is introduced. Dual approach was used to solve the stated optimal identification task resulting in the hierarchical two-stage identification scheme. In the first stage, dual problem is solved in two levels and the vector of non-negative model parameters is computed to provide the best fit of the relaxation modulus to experiment data. Next, in second stage, the optimal non-negative spectrum model is determined. A co

关键词： relaxation spectrum linear relaxation modulus non-negative model identification algorithm least-squares identification smoothing constraint dual optimization problem

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Measurement and identification of the in-plane dynamic behaviour of a rolling tyre

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2024年 211卷

作者： La Paglia, Ivano Rapino, Luca Ripamonti, Francesco Baro, Simone Corradi, Roberto Politecn Milan Dept Mech Engn Via La Masa 1 I-20156 Milan Italy Pirelli Tyre SpA Viale Piero & Alberto Pirelli 25 IT-20126 Milan Italy

Road vehicle NVH performances can be improved acting on tyres, which play a fundamental role in the transmission of structure-borne noise and vibration into the cabin, up to 500 Hz. This paper aims at investigating the in-plane dynamics of a rolling tyre in this frequency range. Tyre radial vibration measurements are carried out through a dedicated experimental setup, based on a laser triangulation sensor scanning the tread of a rolling tyre. The experimental data are collected during cleat tests, considering different rolling speeds and inflation pressures, to investigate their influence on tyre dynamics. Then, a data processing algorithm is proposed with the aim of identifying the progressive and regressive waves propagating along the tyre circumference after the cleat impact. Finally, to interpret the results, the identified tyre response has been compared to the analytical results obtained through a simplified in-plane tyre model.

关键词： Rolling tyre dynamics Experimental cleat test Wave propagation solution identification algorithm Structure-borne noise

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High Accuracy Near-Field Electromagnetic Emission identification System Using Characteristics Recognition and Image Localization

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2023年 72卷 1页

作者： Peng, Yanhua Xu, Hui Zhou, Hangyi Jiang, Ziheng Shen, Dongdong Cui, Shuo Su, Donglin Beihang Univ Sch Elect & Informat Engn Beijing 100191 Peoples R China Beihang Univ Res Inst Frontier Sci & Technol Innovat Beijing 100191 Peoples R China

In this article, an automatic near-field measurement system is introduced to record the electromagnetic emission (EME) of equipment under testing (EUT). First, a camera is used to capture the measurement area, which is combined with an image positioning method to achieve fast and accurate positioning of the area. Then, based on the wavelet transform and autocorrelation transform of the EME signal identification algorithm, the system further identifies the broadband and narrowband characteristics of the signal and obtains the power distributions of the corresponding characteristics. In performance tests, the near-field probe moves with a minimum stepping accuracy of 0.1 mm. The movement error of the consistency and stability are guaranteed as less than 1% of the set value. The image positioning error in the 30 x 30 cm scanned area is less than 0.5 mm. Finally, the system identifies EME signals from a circuit with multiple crystal oscillators and a sine signal, predictive identification of the circuit functions under the metal shell of a router system. The proposed measurement system therefore offers great measurement accuracy, stability, and efficiency.

关键词： Camera image electromagnetic emission (EME) identification algorithm near field measurement system physical characteristics

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Direct identification of the Continuous Relaxation Time and Frequency Spectra of Viscoelastic Materials

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MATERIALS 2024年第19期17卷 4870页

作者： Stankiewicz, Anna Univ Life Sci Lublin Fac Prod Engn Dept Technol Fundamentals PL-20612 Lublin Poland

Relaxation time and frequency spectra are not directly available by measurement. To determine them, an ill-posed inverse problem must be solved based on relaxation stress or oscillatory shear relaxation data. Therefore, the quality of spectra models has only been assessed indirectly by examining the fit of the experiment data to the relaxation modulus or dynamic moduli models. As the measures of data fitting, the mean sum of the moduli square errors were usually used, the minimization of which was an essential step of the identification algorithms. The aim of this paper was to determine a relaxation spectrum model that best approximates the real unknown spectrum in a direct manner. It was assumed that discrete-time noise-corrupted measurements of a relaxation modulus obtained in the stress relaxation experiment are available for identification. A modified relaxation frequency spectrum was defined as a quotient of the real relaxation spectrum and relaxation frequency and expanded into a series of linearly independent exponential functions that are known to constitute a basis of the space of square-integrable functions. The spectrum model, given by a finite series of these basis functions, was assumed. An integral-square error between the real unknown modified spectrum and the spectrum model was taken as a measure of the model quality. This index was proved to be expressed in terms of the measurable relaxation modulus at uniquely defined sampling instants. Next, an empirical identification index was introduced in which the values of the real relaxation modulus are replaced by their noisy measurements. The identification consists of determining the spectrum model that minimizes this empirical index. Tikhonov regularization was applied to guarantee model smoothness and noise robustness. A simple analytical formula was derived to calculate the optimal model parameters and expressed in terms of the singular value decomposition. A complete identification algorithm was deve

关键词： viscoelasticity relaxation spectra linear relaxation modulus direct spectrum approximation identification algorithm model integral square error noise robustness

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Modeling and estimation of speed dependent bearing and coupling misalignment faults in a turbine generator system

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2021年 151卷 107365-107365页

作者： Lal, Mohit Natl Inst Technol Rourkela Dept Ind Design Rourkela 769008 Odisha India

Faulty machinery generates exaggerated vibration that leads to fatigue and catastrophic failure of critical components of machinery and even sometime worker's life. Hence, the fault free functioning of rotating machinery is the prime objective of many industries. The accurate modeling, thereafter estimation of critical components of any rotating machinery is the best way to achieve the fault free condition. The present research work involves with the development of an algorithm for multi-degrees of freedom turbine-generator system to evaluate speed-dependent bearings and coupling misalignment faults, numerically and experimentally. The modeling and simultaneous estimation of speed-dependent bearing and misalignment parameters in addition with speed independent unbalance parameters are the novelty of the present research. In theoretical analysis, finite element method is applied to derive equations of motion of the dynamic system. Least squares technique is used to evaluate the fault characteristic parameters of the turbine-generator system. To test the algorithm additive noise is added in the numerically generated response, and found the algorithm performs well even in the presence of noisy response. In experimental analysis, at randomly selected spin speeds, three sets of forced responses are captured at four bearing locations. These forced responses are imported into the developed algorithm and characteristic parameters are evaluated experimentally. The maximum standard deviation achieved in the quantification of parameters for three sets of data is 2.3 and 2.5 for 29 Hz and 31 Hz, respectively. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： identification algorithm Experimental verification Speed-dependent parameters Finite element method modeling Misalignment Multiple fault parameters

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A Class of algorithms for Recovery of Continuous Relaxation Spectrum from Stress Relaxation Test Data Using Orthonormal Functions

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POLYMERS 2023年第4期15卷 958-958页

作者： Stankiewicz, Anna Univ Life Sci Lublin Fac Prod Engn Dept Technol Fundamentals PL-20612 Lublin Poland

The viscoelastic relaxation spectrum provides deep insights into the complex behavior of polymers. The spectrum is not directly measurable and must be recovered from oscillatory shear or relaxation stress data. The paper deals with the problem of recovery of the relaxation spectrum of linear viscoelastic materials from discrete-time noise-corrupted measurements of relaxation modulus obtained in the stress relaxation test. A class of robust algorithms of approximation of the continuous spectrum of relaxation frequencies by finite series of orthonormal functions is proposed. A quadratic identification index, which refers to the measured relaxation modulus, is adopted. Since the problem of relaxation spectrum identification is an ill-posed inverse problem, Tikhonov regularization combined with generalized cross-validation is used to guarantee the stability of the scheme. It is proved that the accuracy of the spectrum approximation depends both on measurement noises and the regularization parameter and on the proper selection of the basis functions. The series expansions using the Laguerre, Legendre, Hermite and Chebyshev functions were studied in this paper as examples. The numerical realization of the scheme by the singular value decomposition technique is discussed and the resulting computer algorithm is outlined. Numerical calculations on model data and relaxation spectrum of polydisperse polymer are presented. Analytical analysis and numerical studies proved that by choosing an appropriate model through selection of orthonormal basis functions from the proposed class of models and using a developed algorithm of least-square regularized identification, it is possible to determine the relaxation spectrum model for a wide class of viscoelastic materials. The model is smoothed and robust on measurement noises;small model approximation errors are obtained. The identification scheme can be easily implemented in available computing environments.

关键词： viscoelasticity relaxation spectrum linear relaxation modulus identification algorithm orthonormal functions Tikhonov regularization singular value decomposition

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