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An efficient multibody dynamics model for internal combustion engine

MULTIBODY SYSTEM DYNAMICS 2003年第4期10卷 363-391页

作者： Ma, ZD Perkins, NC Univ Michigan Dept Mech Engn Ann Arbor MI 48109 USA

The equations of motion for the major components in an internal combustion engine are developed herein using a recursive formulation. These components include the ( rigid) engine block, pistons, connecting rods, (flexible) crankshaft, balance shafts, main bearings, and engine mounts. Relative coordinates are employed that automatically satisfy all constraints and therefore lead to the minimum set of ordinary differential equations of motion. The derivation of the equations of motion is automated through the use of computer algebra as the precursor to automatically generating the computational (C or Fortran) subroutines for numerical integration. The entire automated procedure forms the basis for an engine modeling template that may be used to support the up-front design of engines for noise and vibration targets. This procedure is demonstrated on an example engine under free ( idealized) and firing conditions and the predicted engine responses are compared with results from an ADAMS model. Results obtained by using different bearing models, including linear, nonlinear, and hydrodynamic bearing models, are discussed in detail.

关键词： engine modeling recursive algorithm symbolic programming journal bearing flexible MBD

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recursive second-order Volterra filter based on Dawson function for chaotic memristor system identification

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NONLINEAR DYNAMICS 2020年第4期99卷 3123-3142页

作者： Lu, Lu Yang, Xiaomin Wang, Wenyuan Yu, Yi Sichuan Univ Sch Elect & Informat Engn Chengdu 610065 Peoples R China Southwest Jiaotong Univ Sch Elect Engn Chengdu 610031 Peoples R China Southwest Univ Sci & Technol Sch Informat Engn Mianyang 621010 Sichuan Peoples R China

In this paper, we propose a modified version of exponential cost function to improve the stability of adaptive algorithm, where the recursive algorithm is based on the Dawson function. The second-order Volterra (SOV) filter is incorporated into the proposed recursive algorithm, resulting the SOV-ExRLS algorithm, to achieve the improved performance in both alpha-stable and Gaussian environments. Moreover, the mean and mean-square behavior of the SOV-ExRLS algorithm is analyzed. In particular, the proposed cExRLS-IDLMS method is convexly combined with the functional link artificial neural network filter to flexibly model the chaotic memristor system. Simulation studies verify the analytical findings and reveal enhanced identification performance of the proposed algorithms over the existing nonlinear algorithms.

关键词： Volterra system Adaptive filter recursive algorithm Dawson function Chaotic memristor system

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A fast algorithm for sparse support vector machines for mobile computing applications

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NEUROCOMPUTING 2017年 230卷 160-172页

作者： Peng, Jian-Xun Rafferty, Karen Ferguson, Stuart Queens Univ Belfast Sch Elect Elect Engn & Comp Sci Ashby BldgStranmillis Rd Belfast BT9 5AH Antrim North Ireland

This research presents a fast algorithm for projected support vector machines (PSVM) by selecting a basis vector set (BVS) for the kernel-induced feature space, the training points are projected onto the subspace spanned by the selected BVS. A standard linear support vector machine (SVM) is then produced in the subspace with the projected training points. As the dimension of the subspace is determined by the size of the selected basis vector set, the size of the produced SVM expansion can be specified. A two-stage algorithm is derived which selects and refines the basis vector set achieving a locally optimal model. The model expansion coefficients and bias are updated recursively for increase and decrease in the basis set and support vector set. The condition for a point to be classed as outside the current basis vector and selected as a new basis vector is derived and embedded in the recursive procedure. This guarantees the linear independence of the produced basis set. The proposed algorithm is tested and compared with an existing sparse primal SVM (SpSVM) and a standard SVM (LibSVM) on seven public benchmark classification problems. Our new algorithm is designed for use in the application area of human activity recognition using smart devices and embedded sensors where their sometimes limited memory and processing resources must be exploited to the full and the more robust and accurate the classification the more satisfied the user. Experimental results demonstrate the effectiveness and efficiency of the proposed algorithm. This work builds upon a previously published algorithm specifically created for activity recognition within mobile applications for the EU Haptimap project [1]. The algorithms detailed in this paper are more memory and resource efficient making them suitable for use with bigger data sets and more easily trained SVMs.

关键词： Data classification Sparse support vector machines recursive algorithm Sequential training algorithm

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Time series prediction using kernel adaptive filter with least mean absolute third loss function

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NONLINEAR DYNAMICS 2017年第2期90卷 999-1013页

作者： Lu, Lu Zhao, Haiquan Chen, Badong Southwest Jiaotong Univ Sch Elect Engn Chengdu Sichuan Peoples R China Xi An Jiao Tong Univ Sch Elect & Informat Engn Xian Shaanxi Peoples R China

In this paper, a novel kernel adaptive filter, based on the least mean absolute third (LMAT) loss function, is proposed for time series prediction in various noise environments. Combining the benefits of the kernel method and the LMAT loss function, the proposed KLMAT algorithm performs robustly against noises with different probability densities. However, an important limitation of the KLMAT algorithm is a trade-off between the convergence rate and steady-state prediction error imposed by the selection of a certain value for the learning rate. Therefore, a variable learning rate version (VLR-KLMAT algorithm) is also proposed based on a Lorentzian function. We analyze the stability and convergence behavior of the KLMAT algorithm and derive a sufficient condition to predict its learning rate behavior. Moreover, a kernel recursive extension of the KLMAT algorithm is further proposed for performance improvement. Simulation results in the context of time series prediction verify the effectiveness of the proposed algorithms.

关键词： Kernel adaptive filter Least mean absolute third algorithm Variable learning rate (VLR) recursive algorithm Series prediction

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Multi-particle processes in QCD without Feynman diagrams

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2006年第1期559卷 278-281页

作者： Papadopoulos, CG Worek, M NCSR Demokritos Inst Nucl Phys GR-15310 Athens Greece PAS Inst Nucl Phys PL-313420 Krakow Poland

A way to efficiently compute helicity amplitudes for arbitrary tree-level scattering processes in QCD is presented. The scattering amplitude is evaluated recursively through a set of Dyson-Schwinger equations. The computational cost of this algorithm grows asymptotically as 3(n), where n is the number of particles involved in the process, compared to n! in the traditional Feynman graphs approach. Unitary gauge is used and mass effects are available as well. Additionally, the color and helicity structures are appropriately transformed so the usual summation is replaced by the Monte Carlo techniques. (c) 2005 Elsevier B.V. All rights reserved.

关键词： automatic evaluation of helicity amplitudes Dyson-Schwinger equations recursive algorithm Monte Carlo methods

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Frequency-domain recursive robust identification

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2000年第5期23卷 908-910页

作者： Feng, X Lin, CF Coleman, NP Amer GNC Corp Chatsworth CA 91311 USA USA Armament Res Dev & Engn Ctr Automat & Robot Lab AMSTA AR FSF R Picatinny Arsenal NJ 07806 USA

CONVENTIONAL system identification theory is mainly focused on how to obtain a single accurate model of the plant and how to ensure that the obtained model approaches the real model of the plant it is assumed that the best an identification algorithm can provide is a good model that is sufficiently close to the real model. For controller design purposes, this assumption implies that a controller. which is designed for a good model, will exhibit good performance when it is applied to the real plant. Such an assumption has been widely used in control ***, alternative approaches to system identification for controller design have been proposed. One of the alternatives is to derive a family of models instead of a single model to ensure that the true dynamics of the plant are included in the model family. Obviously, this is a more practical approach than conventional ones, especially for those plants with highly complex dynamics, such as aerospace *** this Note, a frequency-domain recursive robust identification algorithm is proposed for a system with unmodeled dynamics. The algorithm yields estimates of the system transfer function at N frequency points on the unit circle, as well as the error bounds of these estimates. Such estimation results provide potential data for the so-called H∞ identification approaches, which in turn provide possible models for Me robust (H∞) controller design.

关键词： Frequency Domain Nutation Damping Single Input Single Output Spacecraft Mission Spinning Spacecraft recursive algorithm Galileo Spacecraft Aerospace System Robotics

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An efficient numerical algorithm for "A novel theoretical breakup kernel function of bubble/droplet in a turbulent flow"

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CHEMICAL ENGINEERING SCIENCE 2004年第12期59卷 2593-2595页

作者： Wang, TF Wang, JF Jin, J Tsing Hua Univ Dept Chem Engn Beijing 100084 Peoples R China

An efficient numerical algorithm was proposed for "A novel theoretical breakup kernel function of bubble/droplet in a turbulent flow". In this algorithm, a recursive method was used to calculate the involved triple integral, which reduced the calculation complexity of a triple integal to a double integral. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： bubble/droplet breakup recursive algorithm

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Re-optimisation of LPC filters for multi-pulse coded excitation - Comment

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ELECTRONICS LETTERS 2000年第12期36卷 1082-1083页

作者： Hacioglu, K Eastern Mediterranean Univ Elect Elect Engn Dept G Magosa 10 Mersin Turkey

For original paper, see D.P. Palomar et al., ibid., vol. 35, no. 13, pp. 1058-9 (1999). Palomar et al. addressed the question of LPC filter re-optimisation and proposed a recursive algorithm that they considered promising. The present commentator shows that the iterative algorithm employed by Palomar is unnecessarily complex because of poor initialisation. The algorithm that uses available speech data at the very first step is shown to perform well. The results of the one-shot algorithm can be used to initiate Paolmar's method to significantly reduce the number of iterations

关键词： filtering theory minimisation one-shot algorithm linear predictive coding iterative methods Filtering methods in signal processing iterative algorithm recursive algorithm Optimisation techniques speech coding initialisation Speech and audio coding multi-pulse coded excitation speech data Interpolation and function approximation (numerical analysis) LPC filter re-optimisation

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NEW algorithm FOR DISTANCE PROTECTION OF HIGH-VOLTAGE TRANSMISSION-LINES

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IEE PROCEEDINGS-C GENERATION TRANSMISSION AND DISTRIBUTION 1988年第5期135卷 436-440页

作者： FIKRI, M ELSAYED, MAH Electrical Engineering Dept College of Engineering Qatar University Doha Qatar

Calculated reactance between relay point and fault represents an accurate estimation of fault distance when the fault resistance or the R/L ratios of the equivalent impedance at line ends are very small. When these conditions are not satisfied, a large error results in locating fault distance due to back-feed effect from the remote end. A new recursive algorithm for distance protection is developed, which accurately determines the fault location by predicting the back-feed current. The prediction needs estimated values of the remote end source impedance to be passed to the relay via a communication link. Trip decision is based on checking the evaluated fault location and its variation with time. The algorithm is validated by digitally simulating transmission lines with different fault conditions taking into consideration the reduction in the generator reactance after fault inception. Simulation results show a fault detection time of about one half-cycle.

关键词： Power system protection high voltage transmission lines Power transmission lines and cables R/L ratios power transmission lines recursive algorithm equivalent impedance power system protection distance protection trip decision fault location fault distance back-feed current EHV lines relay protection fault resistance

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Sequential computation of total least-squares parameter estimates

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2004年第3期27卷 501-503页

作者： Soijer, MW Delft Univ Technol Fac Aerosp Engn NL-2629 HS Delft Netherlands

The most common method to solve an overdetermined set of linear equations is the least-squares estimator (LS). The numerical simplicity of the LS regression estimator and the availability of recursive algorithms are probably the prime reasons behind its extreme proliferation. Although LS regression only acknowledges disturbances in the dependent variables, it is often applied to cases where not only the system's output but also the independent explanatory variables are affected by uncertainties. This applies to many aerospace applications, for example, in the equation error approach to aerodynamic model development and validation from flight-test data. Here, both dependent and independent variables are directly or indirectly derived from measurements on the vehicle states and inputs and are thus corrupted by errors. However, the noise that affects the measurements on the explanatory variables is not properly addressed by an LS estimator. The counterpart of the least-squares estimator that correctly handles the error-in-variables problem is the total-least-squares estimator (TLS). Instead of minimizing the sum of squares of residuals on only the response variable, it seeks to minimize the sum of squares of residuals on all of the variables in the equation. Unfortunately, TLS estimators do not share the desirable computational properties of the ordinary LS estimators. A recursive algorithm that directly propagates a TLS estimate over the incoming measurements is not available.

关键词： Singular Value Decomposition recursive algorithm Flight Testing Computing MATLAB Adaptive Control Systems Numerical Integration Perturbation Method Lambert's Problem

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