The paper presents a spatial distribution of changes of air temperature (T) in the Arctic. Estimates of their spatial relations in the study region were based on a correlation analysis. T in the Arctic is most strongly correlated spatially in winter and spring, and least in summer. The radius of extent of statistically significant correlation coefficients of changes of T at the stations Svalbard Lufthavn, Ostrov Kotelny and Resolute A is equal to 2000-2500 km in winter and 1500-2000 km in summer. An attempt was done to delimit the regions of consistent occurrence of the anomalies T with respect to the signs and magnitudes, as well as of the regions with the most coherent T. The Wroclaw dendrite method was used to solve this problem. Relations of the mean areał T of the climatic regions and of the Arctic as a whole, with the northern hemisphere of temperature and selected climatic factors are presented.
The main aim of the research has been to characterise changes the urban functional areas in Poland over 2002–2017 period. The research was based on J.W. Webb’s population development types method enabling to identify links between natural growth and the migration net. A wider analysis concerned components of real increase which, through feedback, influenced level and population dynamics in these areas. Results of the study showed the diversity of demographic processes within Polish urban functional areas as well as in their cores, which will shape different processes in those areas in the future.
The paper concerns the problem of choosing a criterion for transmission line when lumped parameters analysis is required. First, the formal introduction of transmission line scheme is presented. Secondly, a new criterion for lumped-parameter analysis of transmission line is proposed. The criterion has clear physical meaning and simple mathematical form. The proposed criterion takes into account not only wave length, but also the dissipation of transmission line. The criterion can be easily adjusted to some requirements, such as needed level of no-load output voltage change.
In the paper the results of analysis of an integrated gasification combined cycle IGCC polygeneration system, of which the task is to produce both electricity and synthesis gas, are shown. Assuming the structure of the system and the power rating of a combined cycle, the consumption of the synthesis gas for chemical production makes it necessary to supplement the lack of synthesis gas used for electricity production with the natural gas. As a result a change of the composition of the fuel gas supplied to the gas turbine occurs. In the paper the influence of the change of gas composition on the gas turbine characteristics is shown. In the calculations of the gas turbine the own computational algorithm was used. During the study the influence of the change of composition of gaseous fuel on the characteristic quantities was examined. The calculations were realized for different cases of cooling of the gas turbine expander’s blades (constant cooling air mass flow, constant cooling air index, constant temperature of blade material). Subsequently, the influence of the degree of integration of the gas turbine with the air separation unit on the main characteristics was analyzed.