The literature on exchange rate forecasting is vast. Many researchers have tested whether implications of theoretical economic models or the use of advanced econometric techniques can help explain future movements in exchange rates. The results of the empirical studies for major world currencies show that forecasts from a naive random walk tend to be comparable or even better than forecasts from more sophisticated models. In the case of the Polish zloty, the discussion in the literature on exchange rate forecasting is scarce. This article fills this gap by testing whether non-linear time series models are able to generate forecasts for the nominal exchange rate of the Polish zloty that are more accurate than forecasts from a random walk. Our results confirm the main findings from the literature, namely that it is difficult to outperform a naive random walk in exchange rate forecasting contest.

This paper estimates the magnitude of the Baumol-Bowen and Balassa-Samuleson effects in the Polish economy. The purpose of the analysis is to establish to what extent the differential price dynamics in Poland and in the euro area and the real appreciation of PLN against EUR are explained by the differential in respective productivity dynamics. The historical contribution of the Baumol-Bowen effect to Polish inflation rate is estimated at 0.9 − 1.0 percentage points in the short run. According to estimation results, the Balassa-Samuelson effect contributed around 0.9 to 1.0 percentage point per annum to the rate of relative price growth between Poland and the euro area and 1.0 to 1.2 p.p. to real exchange rate appreciation. The long-run effects are of an approximately twice larger magnitude. Sub-sample calculations and productivity trends over the last decade suggest that this impact should be declining. However, its size is still non-negligible for policymakers in the context of euro adoption in Poland.

A heterogeneous Bertrand duopoly game with bounded rational and adaptive players manufacturing differentiated products is subject of investigation. The main goal is to demonstrate that participation of one bounded rational player in the game suffices to destabilize the duopoly. The game is modelled with a system of two difference equations. Evolution of prices over time is obtained by iteration of a two dimensional nonlinear map. Equilibria are found and local stability properties thereof are analyzed. Complex behavior of the system is examined by means of numerical simulations. Region of stability of the Nash equilibrium is demonstrated in the plane of the speeds of adjustment. Period doubling route to chaos is presented on the bifurcation diagrams and on the largest Lyapunov characteristic exponent graph. Lyapunov time is calculated. Chaotic attractors are depicted and their fractal dimensions are computed. Sensitive dependence on initial conditions is evidenced.

Industrial utilization of fly ash from various kinds of fuel plays an important role in the envi-ronmentally clean and cost effective power production. The primary market for fly ash utilizationis as a pozzolanic addition in concrete production. The paper concerns the concretes containingfly ash called Fly Ash from Biomass (FAB) from co-combustion of hard coal and wood biomass(wood chips). Characterization of the fly ash was carried on by means of X-ray diffractometryand E-SEM/EDS analysis. The results of laboratory studies undertaken to evaluate the influence of FAB on concrete resistance to surface scaling due to cyclic freezing and thawing in the presenceof NaCl solution were presented. The tests were carried out for concretes containing up to 25% offly ash related to cement mass. Additionally, the microstructure of air-voids was described.

It was concluded that the FAB has significant effect on concrete freeze/thaw durability. The re-placement of cement by fly ash from co-combustion progressively transformed the concrete mi-crostructure into less resistant against freeze/thaw cycles and excessive dosage (over 15%) maydangerously increase the scaling.

The method of calculations of a thick plate on the two-parameter layered foundation by the finiteelement method is presented. The numerical model allows to add a few (number of) foundationlayers. The expressions for the element stiffness matrices of the foundation are based on 18-nodezero-thickness interface elements. For modelling of thick plates the 9-node Mindlin element of theLagrange family is used. The formulation of the problem takes into account the shear deformation ofthe plate and unilateral contact conditions between plate and foundation. The tensionless characterof the foundation is achieved by removing from the global stiffness matrix the appropriate partof foundation stiffness attached to the node being in the separation stage. The advantages of theproposed algorithm are illustrated by numerical examples.

The paper describes experimental research of slab-column connections examined on specimendesigned as a part of reinforced concrete structure with flat slabs. The aim of the research wasto verify the efficiency of slab reinforcement concept against punching shear by increasing slab’smechanical reinforcement ratio by applying additional external reinforcement in the form of carbonfiber reinforced polymer (CFRP) strips.

The capacity enhancement in comparison to unstrengthened slab obtained 36%.

In the paper, the Hasofer-Lind index is applied for determining the probability of stability loss oftruss structure under random load. In 1974 Hasofer-Lind proposed a modified reliability index thatdid not exhibit the invariance problem. The “correction” is the evaluation the limit state functionat a point known as the “design point”, instead of the mean values. The design point is generallynot known a priori, an iteration technique must be used to find out the reliability index. The papershows how the reliability index changes under the influence of different variables mean value,standard deviation, and probability density function.

Complex structural engineering projects that involve information-gathering and decision-makingprocesses need to be approached with appropriate systems and tools. As transactional databasesare found to be insufficient for this purpose, engineers are adopting multidimensional informationsystems that have been successfully used in other areas of management, especially business.

This paper presents the possibility to apply numerical simulation in static analysis of reinforcedconcrete structure strengthened with carbon fibre reinforced polymer composite strips (CFRP).Reinforced concrete beams, with strengthening in form values CFRP made of carbon fibres andepoxy resin, featuring various width, as well as non-strengthened bent beams, were analysed. Thesimply supported beams arranged in a free support scheme were subjected to two concentratedforces within full range of loading (until collapse). The numerical analysis was performed throughapplication of the Finite Elements Method (FEM), and the calculation model applied took intoaccount the geometric and physical nonlinearity. The problem was solved by application of thequasi-staticstrategy method of calculations using ABAQUS software. While analysing the results,we focused on the run of changes in structure displacement and development of material damage,up to the point of destruction of the beam.

The behaviour of concrete under quasi-static loadings for uniaxial compression, tension and planestress conditions is studied. The failure criteria of concrete are discussed as well as the methodsof constitutive parameters identification are elaborated. The attention is focus on an energeticinterpretation of selected failure criteria. The numerical example with concrete damage plasticitymaterial model is shown.