Wyniki wyszukiwania - BazTech

1

Wykorzystanie elementów teorii grafów w systemie analiz kryminalnych

Gałuszka A., Bereska D., Simek K., Skrzypczyk K., Daniec K.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 9

278-283

PL

Celem opracowania jest przegląd metod przeszukiwania grafów będących ilustracją graficzną powiązań pomiędzy zdarzeniami, osobami, będącymi przedmiotem dochodzenia, śledztwa. Przyjmuje się, że zdarzenia (osoby), będące przedmiotem śledztwa (dochodzenia), tworzą zbiór wierzchołków grafu, natomiast możliwe powiązania pomiędzy takimi węzłami, wynikające z zebranych w dochodzeniu faktów, tworzą zbiór krawędzi grafu. Dodatkowo przyjmuje się, że siła związku pomiędzy wierzchołkami jest opisana za pomocą liczby, zwanej wagą krawędzi.

EN

Aim of this paper is to review graph methods that can be applied to criminal analysis system. It is assumed that persons (happenings) of the investigation are represented by the vertices of a graph, and possible connections are represented by edges. Additionally it is assumed that the strength of the connection is described by the number, called the weight of the edge.

2

Properties of a Singular Value Decomposition Based Dynamical Model of Gene Expression Data

Simek K.

International Journal of Applied Mathematics and Computer Science

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2003

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Vol. 13, no 3

337-345

EN

Recently, data on multiple gene expression at sequential time points were analyzed using the Singular Value Decomposition (SVD) as a means to capture dominant trends, called characteristic modes, followed by the fitting of a linear discrete-time dynamical system in which the expression values at a given time point are linear combinations of the values at a previous time point. We attempt to address several aspects of the method. To obtain the model, we formulate a nonlinear optimization problem and present how to solve it numerically using the standard MATLAB procedures. We use freely available data to test the approach. We discuss the possible consequences of data regularization, called sometimes "polishing", on the outcome of the analysis, especially when the model is to be used for prediction purposes. Then, we investigate the sensitivity of the method to missing measurements and its abilities to reconstruct the missing data. Summarizing, we point out that approximation of multiple gene expression data preceded by SVD provides some insight into the dynamics, but may also lead to unexpected difficulties, like overfitting problems.

3

Analysis of dynamics of gene exspression using singular value decomposition

Simek K., Kimmel M.

Journal of Medical Informatics & Technologies

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2002

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Vol. 3

MI31--40

EN

Recently, data on multiple gene expression at sequential time points were analyzed, using Singular Value Decomposition (SVD) as a means to capture dominant trends, called characteristic modes, followed by fitting of a linear discrete-time dynamical model in which the expression values at a given time point are linear combinations of the values at a previous time point. We attempt to address several aspects of the method. To obtain the model we formulate a nonlinear optimization problem and present how to solve it numerically using standard MATLAB procedures. We use publicly available data to test the approach. Then, we investigate the sensitivity of the method to missing measurements and its possibilities to reconstruct missing data. Summarizing we point out that approximation of multiple gene expression data preceded by SVD provides some insight into the dynamics but may also lead to unexpected difficulties.