Computational Science and Techniques

The popularity of the internet has led to a very rapid growth of IPv4 (Internet Protocol v4) users. This caused a shortage of IP addresses, so it was created a new version – IPv6 (Internet Protocol v6). Currently, there are two versions of IP for IPv4 and IPv6. Due to the large differences in addressing the protocols IPv4 and IPv6 are incompatible. It is therefore necessary to find ways to move from IPv4 to IPv6. To facilitate the transition from one version to another are developed various mechanisms and strategies. Comparative analysis is done for dual stack, 6to4 tunnel and NAT64 mechanisms in this work. It has helped to reveal the shortcomings of these mechanisms and their application in selection of realization decisions.

Electrocardiograms and heart rate signals short distance transfer to mobile Android devices problem is examined. Energy saving and efficient use of bandwidth issues for signals transfer is discussed. Electrocardiograms and heart rate signaling proximity to mobile Android devices implementation possibilities is analyzed. Electrocardiograms and heart rate signals short distance transfer to mobile Android devices is proposed.

This paper deals with the computational modeling of the pattern formation of luminous bacteria. Two bacterial self-organization models are investigated – Keller-Segel diffusion-advection-reaction type equations and the model with additional oxygen equation. These models were applied for the modeling of fluid cultures of lux-gene engineered Escherichia coli in the cylindrical container as seen from the side in 2 dimensions and in quasi-1 dimension along the top three phase contact line. The spatiotemporal patterns were simulated by using the finite difference technique. By applying these models the influence of the cylindrical container depth on the pattern formation was investigated.

Computational modelling of potential and resonant scattering for short range and Coulomb potentials was investigated in this study. The resonant scattering problem is formulated with the short range potential composed of a spherically symmetric square well and spherically symmetric square barrier. An iteration scheme of a continuous analogue of the Newton method for continuous spectral problem with correct asymptotic in uncoupled partial waves has been developed. The nonlinear representation of the scattering problem for the normalized radial Schrödinger equation is solved numerically using the difference sweep technique. The second order accuracy scheme developed allow to find scattering phases and wave functions as well as investigate their numerical evolution. The scattering phases and wave functions dependence on the scattering problem parameters have been studied.

Given training sample, the problem of classifying Gaussian spatial data into one of two populations specified by conditional autoregressive model (CAR) with different mean functions is considered. This paper concerns with classification procedures associated with Bayes Discriminant Function (BDF) under deterministic spatial sampling design. In the case of complete parametric certainty, the overall misclassification probability associated with aforementioned BDF is derived. This is the extension of the previous one to the CAR case. Spatial weights based on inverse of Euclidean distance and the second and third order neighbourhood schemes on regular 2-dimensional lattice are used for illustrative examples.

Information systems begin to date increasingly faster because of rapidly changing business environment. Usually, small changes are not sufficient to adapt complex legacy information systems to changing business needs. A new functionality should be installed with the requirement of putting business data in the smallest possible risk. Information systems modernization problems are beeing analyzed in this paper and a method for information system modernization is proposed. It involves programming code transformation into abstract syntax tree metamodel (ASTM) and model based transformation from ASTM into knowledge discovery model (KDM). The method is validated on example for SQL language.

During developing an information system is important to create clear models and choose suitable modeling languages. The article analyzes the SRML, SBVR, PRR, SWRL, OCL rules specifying language and UML, DFD, CPN, EPC and IDEF3 BPMN business process modeling language. The article presents business rules and business process modeling languages theoretical comparison. The article according to selected modeling aspects of the comparison between different business process modeling languages ​​and business rules representation languages sets. Also, it is selected the best fit of language set for three layer framework for business rule based software modeling.

Ecological system modelling is a powerful tool that provides better understanding of interspecies interaction. Although a complex model gives more information about the modelled object it also drastically increases the computational time needed to get that information. In this paper a rather simple three trophic level population dynamics model with an evolution mechanism is described which can be run on any personal computer. The performance capacity of the evolution mechanism was shown by running the model 1100 times for both carnivores and herbivores so that only one type of animals could evolve. Also it was shown that attempts of controlling the population abundances with chemicals or by hunting while being somewhat effective still can be overcome by animals if they have the ability to evolve.

OpenCL, a modern parallel heterogeneous system programming language, enables problems to be partitioned and executed on modern CPU and GPU hardware, this increases performance of such applications considerably. Since GPU's are optimized for floating point and vector operations and specialize in them, they outperform general purpose CPU's in this field greatly. This language greatly simplifies the creation of applications for such heterogeneous system since it's cross-platform, vendor independent and is embeddable , hence letting it be used in any other general purpose programming language via libraries. There is more and more tools being developed that are aimed at low level programmers and scientists or engineers alike, that are developing applications or libraries for CPU’s and GPU’s of today as well as other heterogeneous platforms. The tendency today is to increase the number of cores or CPU‘s in hopes of increasing performance, however the increasing difficulty of parallelizing applications for such systems and the even increasing overhead of communication and synchronization are limiting the potential performance. This means that there is a point at which increasing cores or CPU‘s will no longer increase applications performance, and even can diminish performance. Even though parallel programming and GPU‘s with stream computing capabilities have decreased the need for communication and synchronization (since only the final result needs to be committed to memory), however this still is a weak link in developing such applications.

When analyzing stock market data, it is common to encounter observations that differ from the overall pattern. It is known as the problem of robustness. Presence of outlying observations in different data sets may strongly influence the result of classical (mean and standard deviation based) analysis methods or models based on this data. The problem of outliers can be handled by using robust estimators, therefore making aberrations less influential or ignoring them completely. An example of applying such procedures for outlier elimination in stock trading system optimization process is presented.