Computational Science and Techniques

The essential part of amperometric biosensor is an enzyme. It should be selective, i.e., react only with certain substrate. The selectivity of enzyme reduces the set of possible to use enzymes. This paper demonstrates that non selective enzymes (reacting with two substrates) can be used to determine concentrations of two substrates. For this purpose the steady-state current of two double biosensors was measured. The currents were used as input for an artificial neural network to determine concentrations of the substrates. The proposed approach was approved as the relative error of determined concentrations was relatively small. Paper analyses the influence of biosensor parameters to error values. The recommendations to error values minimisation were obtained.

This paper proposes an algorithm for construction of C2 surface. The input is a 3D quadrangular surface which doesn't have adjacent extraordinary points. The difference between this algorithm and the regular C2 forming algorithms is a possibility to choose the natural number of points of the output grid. For example using the Catmull-Clark algorithm the same possibility corresponds exponential natural numbers where the basis is 2. The changing infinite Bezier surfaces generation process to finite calculation of necessary points leads the ability to get more results. The C2 surface generation algorithm was realized and the quality results of output surfaces were performed using reflection lines.

This paper proposes methodology for companies’ assessment. There is suggesting assessing the company’s prospect, not only according to share price, forecasts of the analysts, but also on the basis of position of each company in two-dimensional space in respect of the other companies. Seeking to describe the share prices of a company during the year, the parameters of skew t distribution are calculated. Then they are used in the inputs of random forest algorithm. Proximity matrices are stored during classification, and they are displayed in two-dimensional space. Thus, two clusters are obtained: one of the companies with upgrade trend, another one – with downgrade trend. This method may be useful those investors who are important to choose the most promising companies of all industry without wasting a lot of time.

Lack of ICT specialists is a big problem in Lithuania for many years. Even ICT specialists are prepared both by universities and colleges, need of those specialists is increasing every year. Students’ enrolment to the ICT related study programmes is increasing a little every year, but only around 51% of them complete their studies. There are very different reasons of students drop-out: health problems, characteristics of personality (lack of responsibility, self-doubts, etc.), socio-economic factors, organisation of study process (Barkauskaitė & Gudžinskienė 2006). In this article a different approach is used to academic arrears – using statistical calculations, academic arrears of students of Vilnius University, Faculty of Mathematics and Informatics from 1991 till 2012 are analysed. At the end of the article, justification of a theoretical model is presented, using which students’ drop-out peculiarities in different study programmes can be observed.