A novel framework based on the fast orthogonal search (FOS) method coupled with factorization algorithms was proposed and implemented to realize high-accuracy muscle force estimation via surface electromyogram (SEMG)....
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A novel framework based on the fast orthogonal search (FOS) method coupled with factorization algorithms was proposed and implemented to realize high-accuracy muscle force estimation via surface electromyogram (SEMG). During static isometric elbow flexion, high-density SEMG (HD-SEMG) signals were recorded from upper arm muscles, and the generated elbow force was measured at the wrist. HD-SEMG signals were decomposed into time-invariant activation patterns and time-varying activation curves using three typical factorization algorithms including principal component analysis (PCA), independent component analysis (ICA), and nonnegative matrix factorization (NMF). The activation signal of the target muscle was obtained by summing the activation curves, and the FOS algorithm was used to create basis functions with activation signals and establish the force estimation model. Static isometric elbow flexion experiments at three target levels were performed on seven male subjects, and the force estimation performances were compared among three typical factorization algorithms as well as a conventional method for extracting the average signal envelope of all HD-SEMG channels (AVG-ENVLP method). The overall root mean square difference (RMSD) values between the measured forces and the estimated forces obtained by different methods were 11.79 +/- 4.29% for AVG-ENVLP, 9.74 +/- 3.77% for PCA, 9.59 +/- 3.81% for ICA, and 9.51 +/- 4.82% for NMF. The results demonstrated that, compared to the conventional AVG-ENVLP method, factorization algorithms could substantially improve the performance of force estimation. The FOS method coupled with factorization algorithms provides an effective way to estimate the combined force of multiple muscles and has potential value in the fields of sports biomechanics, gait analysis, prosthesis control strategy, and exoskeleton devices for assisted rehabilitation.
We propose algorithms computing the semi-greedy Lempel-Ziv 78 (LZ78), the Lempel-Ziv Double (LZD), and the Lempel-Ziv-Miller-Wegman (LZMW) factorizations in linear time for integer alphabets. For LZD and LZMW, we addi...
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ISBN:
(纸本)9798350385885;9798350385878
We propose algorithms computing the semi-greedy Lempel-Ziv 78 (LZ78), the Lempel-Ziv Double (LZD), and the Lempel-Ziv-Miller-Wegman (LZMW) factorizations in linear time for integer alphabets. For LZD and LZMW, we additionally propose data structures that can be constructed in linear time, which can solve the substring compression problems for these factorizations in time linear in the output size.
We give memory-friendly algorithms computing the compression schemes plcpcomp or lex-parse in linear or near-linear time, and give upper and lower bounds on the space requirements of our algorithm computing plcpcomp.
ISBN:
(纸本)9781665478939
We give memory-friendly algorithms computing the compression schemes plcpcomp or lex-parse in linear or near-linear time, and give upper and lower bounds on the space requirements of our algorithm computing plcpcomp.
作者：
Conceicao, Ana C.Univ Algarve
Dept Matemat Ctr Funct Anal Linear Struct & Applicat CEAFEL P-8005139 Faro Portugal
Operator theory has many applications in several main scientific research areas (structural mechanics, aeronautics, quantum mechanics, ecology, probability theory, electrical engineering, among others) and the importa...
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Operator theory has many applications in several main scientific research areas (structural mechanics, aeronautics, quantum mechanics, ecology, probability theory, electrical engineering, among others) and the importance of its study is globally acknowledged. On the study of the operator's kernel some progress has been achieved for some specific classes of singular integral operators whose properties allow the use of particular strategies. However, the existing algorithms allow, in general, to study the dimension of the kernel of some classes of singular integral operators but are not designed to be implemented on a computer. The main goal of this paper is to show how the symbolic and numeric capabilities of a computer algebra system can be used to study the kernel of special classes of paired singular integral operators with essentially bounded coefficients defined on the unit circle. It is described how some factorization algorithms can be used to compute the dimension of the kernel of special classes of singular integral operators. The analytical algorithms [ADimKerPaired-Scalar], [AKerPaired-Scalar], and [ADimKerPaired-Matrix] are presented. The design of these new algorithms was focused on the possibility of implementing on a computer all the extensive symbolic and numeric calculations present in the algorithms. For the essentially bounded hermitian coefficients case, there exist some relations with Hankel operators. The paper contains some interesting and nontrivial examples obtained with the use of a computer algebra system.
The paper analyzes existing factorization algorithms and classifies them. The elaboration of the factorization algorithm which allows working with both small and large numbers is presented. Whereas the replacement of ...
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ISBN:
(纸本)9781728140681
The paper analyzes existing factorization algorithms and classifies them. The elaboration of the factorization algorithm which allows working with both small and large numbers is presented. Whereas the replacement of operations of addition and multiplication by the operation of addition, in comparison with the existing algorithms, a large gain of time is achieved. The initiation of operation of inequality solution allows cutting up to N-1/4 of possible candidates for a single calculation step. The evaluation of the time of the algorithm was conducted. It is comparable to the best known.
On the Hilbert space the singular integral operator with non-Carleman shift and conjugation is considered, where are the Cauchy projectors, , , , are continuous functions on the unit circle , U is the shift operator a...
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On the Hilbert space the singular integral operator with non-Carleman shift and conjugation is considered, where are the Cauchy projectors, , , , are continuous functions on the unit circle , U is the shift operator and C is the operator of complex conjugation. We show how the symbolic computation capabilities of the computer algebra system Mathematica can be used to explore the dimension of the kernel of the operator K. The analytical algorithm [ADimKer-NonCarleman] is presented;several nontrivial examples are given.
作者：
Conceicao, Ana C.Pereira, Jose C.Univ Algarve
Ctr Funct Anal Linear Struct & Applicat CEAFEL Fac Ciencias & Tecnol Dept Matemat P-8005139 Faro Portugal Univ Algarve
Ctr Funct Anal Linear Struct & Applicat CEAFEL Ctr Environm & Sustainabil Res CENSE Dept Engn Elect & InformatFac Ciencias & Tecnol P-8005139 Faro Portugal
Spectral theory has many applications in several main scientific research areas (structural mechanics, aeronautics, quantum mechanics, ecology, probability theory, electrical engineering, among others) and the importa...
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Spectral theory has many applications in several main scientific research areas (structural mechanics, aeronautics, quantum mechanics, ecology, probability theory, electrical engineering, among others) and the importance of its study is globally acknowledged. In recent years, several software applications were made available to the general public with extensive capabilities of symbolic computation. These applications, known as computer algebra systems (CAS), allow to delegate to a computer all, or a significant part, of the symbolic calculations present in many mathematical algorithms. In our work we use the CAS Mathematica to implement for the first time on a computer analytical algorithms developed by us and others within the Operator Theory. The main goal of this paper is to show how the symbolic computation capabilities of Mathematica allow us to explore the spectra of several classes of singular integral operators. For the one-dimensional case, nontrivial rational examples, computed with the automated process called [ASpecPaired-Scalar], are presented. For the matrix case, nontrivial essentially bounded and rational examples, computed with the analytical algorithms [AFact], [SInt], and [ASpecPaired-Matrix], are presented. In both cases, it is possible to check, for each considered paired singular integral operator, if a complex number (chosen arbitrarily) belongs to its spectrum.
We review experiments supporting the hypothesis that the vertebrate motor system produces movements by combining a small number of units of motor output. Using a variety of approaches such as microstimulation of the s...
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We review experiments supporting the hypothesis that the vertebrate motor system produces movements by combining a small number of units of motor output. Using a variety of approaches such as microstimulation of the spinal cord, NMDA iontophoresis, and an examination of natural behaviors in intact and deafferented animals we have provided evidence for a modular organization of the spinal cord. A module is a functional unit in the spinal cord that generates a specific motor output by imposing a specific pattern of muscle activation. Such an organization might help to simplify the production of movements by reducing the degrees of freedom that need to be specified. (c) 2007 Elsevier B.V. All rights reserved.
We study a class of block structured matrices R = {R-ij}(i,j=1)(N) with a property that the solution of the corresponding system Rx = y of linear algebraic equations may be performed for O(N) arithmetic operations. In...
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We study a class of block structured matrices R = {R-ij}(i,j=1)(N) with a property that the solution of the corresponding system Rx = y of linear algebraic equations may be performed for O(N) arithmetic operations. In this paper for finite invertible matrices we analyze in detail factorization and inversion algorithms. These algorithms are related to those suggested by P.M. Dewilde and A.J. van der Veen (Time-varying Systems and Computations, Kluwer Academic Publishers, New York, 1998) for a class of finite and infinite matrices with a small Hankel rank. The algorithms presented here are more transparent and are a modification of the algorithms from the above reference, The approach and the proofs are essentially different from those in the above-mentioned reference. The paper contains also analysis of complexity and results of numerical experiments. (C) 2002 Elsevier Science Inc. All rights reserved.
Recently the research in the area of search and rescue satellite aided tracking (SARSAT) has gained great impetus. The efficiency of the search and rescue (SAR) program depends, amongst other factors, on the accuracy ...
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Recently the research in the area of search and rescue satellite aided tracking (SARSAT) has gained great impetus. The efficiency of the search and rescue (SAR) program depends, amongst other factors, on the accuracy of the position information of the distressed platform, e.g. a downed aircraft. This in turn depends on the accuracy of the estimate of the SARSAT satellite's orbital position. In the present work we utilize extended Kalman Kilter (EKF) and UD-Kilters (UDF) to estimate the orbital position of a SARSAT satellite. We study the effect of two sets of observables and a certain a priori statistics on the position and velocity estimates. Altman's Unified State Model (USM) is used for the orbital trajectory dynamics and angles and range are used as observables. The results of the comparison of four orbit estimators are presented for simulated data obtainable from a ground based observation site.
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