Structural changes occurring in the crude oil market have stimulated the emergence of hypotheses suggesting that the relationship between prices of this raw material and the US dollar exchange rate can gradually become similar to that observed between oil prices and exchange rates of the currencies of the countries whose revenues from the export of this resource are a significant part of their current account balance. The purpose of this study was to determine and evaluate the time-varying dependence between oil prices and the exchange rate of the US dollar in the context of the same relationship for the Chinese, European, Japanese, Saudi, and Russian currencies. The results of our analyses implicate that a negative correlation between the variables in question grows stronger in time periods preceding global shocks and during thereof. The dominance of the USD in the crude oil market is reflected in similar characteristics of the correlations of the currencies of other countries, such as China, countries of the Euro area, or Japan. As for countries exporting crude oil, the situation varies. The results of our research suggest the lack of a stable relationships between prices of crude oil and currency exchange rates. It is also impossible to observe a long-term, unequivocal tendency of the currencies of oil exporting countries being positively correlated with oil prices. Russia was the closest to this situation. In Saudi Arabia, a positive correlation emerged during moments of crisis.

Natural resources play a significant role in the development of the global economy. This refers, in particular, to strategic fuel and mineral resources. Due to the limited supply of natural resources and the lack of substitutes for most of the key resources in the world, the competition for the access to strategic resources is a feature of the global economy. It would seem that the countries which are rich in resources, because of this huge demand, enjoy spectacular economic prosperity. However, the results of empirical studies have demonstrated what is known as the ‘resource curse’. This article concentrates on the characteristics of the paradox of plenty, and in particular on the possibilities of preventing this phenomenon. The aim of this article is to identify the measures of economic policy with which to counteract the resource curse, based on the relationship between the state and the extraction business. Upon the critical analysis of the relevant literature, we concluded that the state’s economic policy, implemented in cooperation with the extraction business, is increasingly important for the prevention of the resource curse. In the context of the resource curse, the optimal and most consensual instrument, in comparison with other resource sharing agreements, is a production sharing agreement (PSA), which should also be adjusted to the current local economic conditions in a given country.

No abstract

W artykule dokonano analizy zależności pomiędzy rozmiarami szarej strefy a bezpieczeństwem państwa. W państwach, w których znaczącą rolę odgrywa szara strefa gospodarcza, jej przejawem jest niska ściągalność podatków. Prowadzi to ograniczenia tzw. rękojmi podatkowej rządu, zwiększa dług publiczny i prawdopodobieństwo jego przyszłej restrukturyzacji. Celem badań była identyfikacja związku pomiędzy publicznym zadłużeniem, ryzykiem niewypłacalności oraz rozmiarami szarej strefy gospodarczej, jako wyznacznikami poziomu bezpieczeństwa finansowego państwa. Zakres przedmiotowy badania stanowił wpływ szarej strefy gospodarczej na bezpieczeństwo finansowe państw. Zakresem podmiotowym badania objęto grupę 50 krajów, zróżnicowanych pod względem rozmiarów gospodarki i szarej strefy. Zakres czasowy badań objął okres 5 lat. Rezultaty badania empirycznego wykorzystującego regresje wskazują na istotny wpływ rozmiarów szarej strefy na ryzyko niewypłacalności rządu, napięcia finansowe sytemu oraz koszty obsługi długu.

The potential absorption of solar energy in photovoltaic thermal (PVT) hybrid solar collectors at different tilt angles was compared in the present study. The optimal tilt angles were tested in three variants: during 1 day, 1 year and a period of 30 years. Simulations were performed based on actual weather data for 30 years, including average hourly total radiation, insolation and air temperature. The apparent movement of the Sun across the sky, solar radiation properties, and the electrical and thermal efficiency of a PVT collector were also taken into account in the simulation model. The optimal orientation of the absorber surface was determined by solving an optimization task. The results of the study indicate that in the long-term perspective, the collector’s performance is maximized when the absorber is positioned toward the south at an elevation angle of 34.1°.