We investigate here how the geometric control theory of Basile, Marro and Wonham can be obtained in a Hilbert space context, as the byproduct of the factorization of a spectral density with no zeros on the imaginary axis. We show how stabilizable and controllability subspaces can be obtained as images of orthogonal projections of coinvariant subspaces onto a semiinvariant (markovian) subspace o...

This paper contributes the analysis of the persistence of innovation activities, as measured by total factor productivity (TFP) and explores its internal and external determinants stressing its path dependent characteristics. The external conditions, namely the quality of local knowledge pools and the strength of the Schumpeterian rivalry, together with the internal conditions, that is the actu...

Opinion mining is a natural language processing technique which extracts subjective information from natural language text. To estimate an opinion about a query in large data collection, an opinion retrieval system that retrieves subjective and relevant information about the query can be useful. We present an opinion retrieval system that retrieves subjective and query-relevant tweets from Twit...

We study the geometric structure of the spectral factors of a given spectral density Φ. We show that these factors can be associated to a set of invariant subspaces and we exhibit the manifold structure of this set, providing also an explicit parametrization for it, in the special case of coinciding algebraic and geometric multiplicity of the zeros of the maximum-phase spectral factor. We also ...

There is a seasonal cycle of sexual activity for all species of birds. It is more or less pronounced according to the species, and it is primarily controlled by the external factor of light, the daily duration and intensity of which vary during -the year, the minimum amount of light being present on December 21, while the maximum is reached on June 21 in the northern hemisphere. Rowan54 was the...

introduction: the present research which carried out goal was assessing mothvation factors in nurses who in semnan university of medical science hospitals. methods: this was a descriptive- analytical study. the statistical population of this research includes 100 nurses who work in critical care units. study tools were prepared in the basis of the standard questionnaires of hers berg theory .th...

Nowadays, industrialization exposes the human and environment resources to serious dangers. The importance of these resources caused the HSE (health, safety and environment) to have a significant contribution in industries’ evaluation, especially in construction industry. While evaluating the project’s success from an HSE point of view, it is not enough to rely solely on the outputs without con...