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The approach to the mathematical analysis of fracture toughness of the gas mains steel is proposed, which allows obtaining informative features of the quantitative evaluation of the dynamic pipe fracture kinetics, taking into account the stochastic and cyclic nature of the process. It creates the possibility to model the kinetics of crack propagation in the gas mains pipe and analyzing individual stages of its growth.

On an example of testing sheet high-strength (α + β) titanium alloys with different percentages of α and β phases, the danger of using titanium alloys with a large α phase content in transportation systems subjected to impact-oscillatory loading is shown. Under impact-oscillatory loading, dynamic nonequilibrium processes (DNP) with self-organization of the structure can be realized in titanium alloys. As a result, depending on the initial percentage of α and β phases in alloys, the impact-oscillatory loading can significantly affect fluctuations in the initial plastic deformation of the alloys upward or downward without appreciably reducing the strength of the alloy.

This paper reviews the of transportation risk assessment in the Latvia and Lithuania ports. The essential steps of assessment are the identification of primary criterions, the determining the underlying criterion groups and quantitative assessment of international environment indicators and nature, infrastructure indicators and organizational indicators. Designed system of criteria creates a possibility for objective evaluation of risk management processes and allows planning objectively long-term risk management strategy in the Latvia and Lithuania ports according to certain economic development circumstances.

The paper presents various scientific interpretations of the concept of competition, the concept of a competitive environment, methods and models of competitive environment assessment and the competition factors that influence the activities of the company are presented as well. According to this literature assessment, the analysis of competitive environment of passenger transportation of JC “Lithuanian Railways” was carried out and the forecast of passenger transportation was provided for all modes in 2017–2021.

This paper presents a two-dimensional-in-space mathematical model of an amperometric biosensor based on an enzyme-loaded carbon nanotubes layer deposited on a perforated membrane. The developed model is based on nonlinear non-stationary reaction-diffusion equations. By changing input parameters the output results are numerically analysed with a special emphasis to the influence of the geometry and the catalytic activity of the biosensor to its response. The numerical simulation at transition and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and experimental data was admissible at different concentrations of the substrate and the mediator.

The response of a laccase-based amperometric biosensor that acts in a synergistic manner was modelled digitally. A mathematical model of the biosensor is based on a system of non-linear reaction diffusion equations. The modelling biosensor comprises three compartments, an enzyme layer, a dialysis membrane and an outer diffusion layer. By changing input parameters the biosensor action was analysed with a special emphasis to the influence of the species concentrations on the synergy of the simultaneous substrates conversion. The digital simulation was carried out using the finite difference technique.

The article presents a critical analysis of one of the aspects of collective labour relations, mainly employee representation at the company level via works councils. The emergence of the institute of works councils in Lithuania was determined by general Euro-integration processes and the need to develop and promote social dialogue. As we know, after the restoration of independence in Lithuania employee representation at the company level by trade unions was very poor. Therefore, with the view to taking over the tradition of collective labour relations prevailing in Western Europe and promoting the process of collective bargaining and collective agreements, a special law was adopted in Lithuania in 2004 to provide for the establishment and functioning of an alternative employee representation body, works councils. This article aims to reveal, by means of various research methods, the content of EU and national legal norms governing the status of works councils and to show, based on various surveys conducted in the country, the current realistic situation of employee representation in Lithuania.

The paper concentrates on aspects of real estate investment risk management and highlights risk reduction abilities of diversified investment portfolio. The core problem of the paper is the investment decision making under risk which can arise due to instable market conditions and ever changing levels of prices. Throughout the investigation of this problem could be useful, in both practical and theoretical areas, to provide an insight of riskiness of investment possibilities in Western and Eastern Europe as well as to provide material for further theoretical investigations. The main goal of this work is to discuss the nature of real estate investment risks and to form real estate investment portfolio with application to European markets in order to find an investment solution according to risk. Altogether with mean-variance portfolio scheme, the idea of adequate for stochastic nature of investment efficiency portfolio is used in constructing corresponding three-investment portfolio sets helping to select optimal ones for different investors.

This paper presents a mathematical model of a potentiometric biosensor based on a potentiometric electrode covered with an enzyme membrane. The model is based on the reaction–diffusion equations containing a non-linear term related to the Michaelis–Menten kinetics of the enzymatic reaction. Using computer simulation the influence of the thickness of the enzyme membrane on the biosensor response was investigated. The digital simulation was performed using the finite difference technique. Results of the numerical simulation were compared with known analytical solutions.

This paper presents a two-dimensional-in-space mathematical model of amperometric biosensors with perforated and selective membranes. The model is based on the diffusion equations containing a non-linear term of the Michaelis–Menten enzymatic reaction. Using numerical simulation of the biosensors action, the influence of the geometry of the perforated membrane on the biosensor response was investigated. The numerical simulation was carried out using finite-difference technique. The calculations demonstrated non-linear and non-monotonous change of the biosensor steady-state current at various degree of the surface of the perforated membrane covering. The non-monotonous behaviour of the biosensor response was also observed when changing the thickness of the perforated membrane.