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Modified Algorithm (modified + algorithm)

Distribution by Scientific Domains
Chemistry57%
Mathematics and Statistics28%

Selected Abstracts

Extension of discrete simple adaptive control with asymptotically perfect tracking,

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2 2002
H. Shibata
Abstract A discrete-time algorithm for simple adaptive control, proposed by one of authors, circumvents some drawbacks of the algorithm derived directly from continuous-time one. However, it leaves steady-state output error between a controlled plant and a reference model. This paper proposes a modified algorithm, which removes the steady-state output error. The stability of the algorithm is proved based on asymptotic output tracker theory, instead of command generator tracker theory. Finally, simulation results illustrate satisfactory control performance, that verifies the usefulness of the proposed algorithm. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Orthogonal signal correction: algorithmic aspects and properties

JOURNAL OF CHEMOMETRICS, Issue 11 2002
Baibing Li
Abstract The objective of this paper is to present a modified algorithm for the orthogonal signal correction (OSC) filter based on the approaches proposed by Wold, Antti, Lindgren and Öhman (Chemometrics Intell. Lab. Syst. 1998; 44: 175,185) and Fearn (Chemometrics Intell. Lab. Syst. 2000; 50: 47,52). An OSC filter consists of a trio of building blocks: weights, components and loadings, . The original OSC filter of Wold et al. was based on the framework of the non-linear iterative partial least squares (NIPALS) algorithm. Adopting this approach enabled the mathematical justification for the selection of the loading vectors pj and components tj, but there was no theoretical foundation for the selection of wj. In contrast, the approach of Fearn described an objective function for the selection of the weight vectors wj, but in this case there is no theoretical justification for either pj or tj. Combining both approaches, within a NIPALS framework, enables a clear theoretical basis for the selection of all three building blocks to be established. A number of orthogonal and optimal properties of the NIPALS-based OSC algorithm, although previously reported, are also theoretically proven. Finally, it is shown that the modified OSC algorithm is equivalent to Fearn's OSC but is interpretable as a consequence of it being presented from a NIPALS perspective. This enables the possible extension of OSC to dynamic and non-linear systems. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Prediction of Volatile Components Retention Time in Blackstrap Molasses by Least-Squares Support Vector Machine

MOLECULAR INFORMATICS, Issue 5 2008
Yongna Yuan
Abstract House flies are pestiferous insects that have the potential to spread many diseases to humans and livestock, so it is very significant for us to manage house fly populations. Many commercial types of bait are available to attract house flies, but most are designed for outdoor or limited indoor use, due to their malodorous components. This study sought to identify compounds present in blackstrap molasses that might be attractive to house flies. An effective Quantitative Structure-Property Relationship (QSPR) model between the Retention Time (RT) and five molecular descriptors of the volatile compounds in blackstrap molasses, was built using a modified algorithm of Least-Squares Support Vector Machine (LS-SVM). Descriptors calculated from the molecular structures alone were used to represent the characteristics of compounds. The five molecular descriptors selected by the Heuristic Method (HM) in CODESSA were used as inputs for LS-SVM. The results obtained by LS-SVM were compared with those obtained by the HM. The LS-SVM model gives better results with the predicted correlation coefficient () 0.919 and Root Mean-Square Errors (RMSE) 2.193 for the test set, as well as that 0.824 and 2.728 in the MLR model. The prediction results of log RT are in very good agreement with the experimental values. This paper provided a new and effective method for predicting the chromatography retention index. [source]

A note on the complex semi-definite matrix Procrustes problem

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 6 2007
J. Kiskiras
Abstract This note outlines an algorithm for solving the complex ,matrix Procrustes problem'. This is a least-squares approximation over the cone of positive semi-definite Hermitian matrices, which has a number of applications in the areas of Optimization, Signal Processing and Control. The work generalizes the method of Allwright (SIAM J. Control Optim. 1988; 26(3):537,556), who obtained a numerical solution to the real-valued version of the problem. It is shown that, subject to an appropriate rank assumption, the complex problem can be formulated in a real setting using a matrix-dilation technique, for which the method of Allwright is applicable. However, this transformation results in an over-parametrization of the problem and, therefore, convergence to the optimal solution is slow. Here, an alternative algorithm is developed for solving the complex problem, which exploits fully the special structure of the dilated matrix. The advantages of the modified algorithm are demonstrated via a numerical example. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Symmetry-modified charge flipping

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 2 2009
Alexander Eggeman
The charge-flipping algorithm has been adapted to allow symmetry constraints to be included during the solution of structures from diffraction data. Rather than impose symmetry at the start of the algorithm, which is known to cause the process to stagnate, it is shown that the algorithm must be allowed to find an intermediate stable solution first. Although care is needed when using this modified algorithm, the improvement in the fidelity of the structure solution is considerable. [source]

Ab initio structure solution by charge flipping.

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 1 2005

The original charge flipping algorithm [Oszlnyi & St (2004). Acta Cryst. A60,34141] is an amazingly simple structure solution method which works ab initio on high-resolution X-ray diffraction data. In this paper, a new version of the algorithm is presented that complements the phase exploration in reciprocal space. Instead of prescribing observed moduli of all structure factors, weak reflections are treated separately. For these reflections, calculated moduli are accepted unchanged and calculated phases are shifted by a constant ,, = ,/2. This means that the observed data of weak reflections are not used in the iteration, except for the knowledge that they are indeed weak. The improvement is drastic, in some cases the success rate is increased by a factor of ten, in other cases a previously unsolvable structure becomes solvable by the modified algorithm. [source]

Damping factor in Google page ranking

APPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 5-6 2006
Hwai-Hui Fu
Abstract Google, the largest search engine worldwide, adopts PageRank technology to determine the rank of website listings. This paper describes how damping factor is a critical factor in changing a website's ranking in traditional Google PageRank technology. A modified algorithm based on input,output ratio concept is proposed to substitute for the damping factor. Besides there is no need to choose an optimal damping factor value, the modified algorithm has an equivalent effect on computation as the traditional Google's PageRank algorithm. Copyright © 2006 John Wiley & Sons, Ltd. [source]