Showing papers by "University of Maribor published in 1988"

Thermal properties of binary polyolefin blends

Abstract: The thermal properties of binary polyolefin blends (LDPE/HDPE, LDPE/PP, HDPE/PP) were examined by differential scanning calorimetry. The additon of a second polymer lowers the melting temperature although the melting temperature depression is not a defined function of the blend composition. DSC curves show two melting and two crystallization temperatures. The difference between crystallization temperatures for blends containing PP is smaller than the difference between melting temperatures. The enthalpies of fusion are nearly monotonic functions of blend composition.

Molecular motions in poly (ethylene oxide) solutions

Abstract: The motions of solvent and molecules in solutions of poly(ethylene oxide) have been investigated by neutron inelastic scattering measurements. Both the concentration dependence and the influence of the molecular weight of the PEO molecules were studied. It is shown that there exists a strong concentration dependent interaction between a PEO molecule and the surrounding water which affects both the translational and the rotational motions of the water molecules. Thus there is a clear indication of the presence of a hydration shell around each PEO molecule within which the motions of the water molecules are strongly hindered. In carbon tetrachloride solutions the results indicate that there exists a weak interaction of hydrodynamic origin between solvent and solute molecules.

Spreadsheet language level: how high is it?

Abstract: In this paper we briefly describe most important features of the spreadsheet software. Then we present an algorithm for measuring its Halstead's language level. Finaly we analyse the obtained measures.

IMCL language and its implementation on the personal computer

Abstract: The use of traditional industrial controllers has been a common practice for successfully controlling processes in industrial plants for a long time. However, these old-fashioned controllers (Figure 1) are unfortunately inflexible and much too slow and unreliable for critical applications, and not "user friendly." Still worse, programming them is tedious, lengthy and difficult. LSI and VLSI technology with their 16- and 32-bit processors has permitted a new approach to the design and use of industrial controllers (Figure 2). The shift from MAD (Manually Aided Design) to CAD has been the most important result of this shift to date. But finally, newly emerging concepts of parallel computing, applicative languages and non-yon Neumann architecture have awakened our hopes of employing the computer to liberate the human (Figure 3).

Some remarks on derivations in Banach algebras and related results.

Abstract: In the first section of this paper we consider some functional equations which are closely connected to derivations (i.e. additive mappings with the propertyD(ab) = aD(b) + D(a)b) on Banach algebras. IfD is a derivation on some algebraA, then the equationD(a) = − aD(a−1)a holds for all invertible elementsa ∈A. It seems natural to ask whether this functional equation characterizes derivations among all additive mappings. It is too much to expect an affirmative answer to this question in arbitrary algebras, since it may happen that even in normed algebras the group of all invertible elements contains only scalar multiples of the identity. We try to answer the question above in Banach algebras, since in Banach algebras invertible elements exist in abundance. In the second section of the paper we prove some results concerning representability of quadratic forms by bilinear forms.

A Methodology for Efficiency Estimation of the Speech Signal Feature Extraction Methods

Abstract: This paper deals with a basis of methodology for speech signal feature description. Speech signal is described by three sets of features (the set of all descriptive features, the set of all selected features, and the set of all characteristic features). Feature description methods are described by three sets of maps (descriptive feature map, selected feature map, and characteristic feature map). As an example two feature description methods are considered — zero — crossing method and method of formant frequency energy classes (variant a and b). Efficiency of a single method being used in the recognition process has been estimated on the basis of experimental results. It is shown that the Fourier transformation as a map of descriptive features is more convenient as a measurement of time interval lenght. The mapping rule in variant b of the method of formant frequency energy classes gives a more convenient map of selected features than the mapping rule in variant a. With these maps the smallest features overlapping and consequently a better average recognition accuracy (greater than 92.5 %) can be achieved.

Boundary Elements for Non-Stationary Mixed-Convection Flow Problems

Abstract: The paper deals with the application of BEM to time dependent energy and momentum transport in laminar flow of an incompressible viscous fluid. The Boussinesq approximation is used to consider the buoyancy effects.