In 1981, Polish canoeists (members of the Bystrze Academic Travel Club) made the first journey along the waters of the River Colca in the section located in Arequipa Province (Peru), along which the waters flow in a deep canyon. Information on this sporting achievement – and a description of the Canyon and its surrounding area filled the Peruvian press and tourist publications around the world, ensuring that the Colca Canyon became one of the most important goals for tourists anywhere in Peru from that time on. However, mass infl uxes of tourists, noisy trips, the development of hotel infrastructure and other items required in tourism have generated permanent change in the character of the Colca Valley, and done much to influence the lives of its inhabitants.

This publication presents the research aimed at developing statistical models, on the basis of which it was possible to prepare credible forecasts of unit cost and coal net output for longwalls in 5 hard coal mines in P oland. The argument has been verified that there is a dependence between the level of nuisance and the level of costs, as well as longwall production results.

A research procedure has been developed for that purpose, which aimed at developing two statistical models connecting the nuisance due to geological and mining conditions with costs and longwall production results. The multiple linear regression technique has been used to develop statistical models. The set of data taken into account in the analyses comprised 120 longwalls mined in the years 2010–2019. Two models have been developed – one for forecasting unit costs, the other for forecasting coal net output. Subsequently, the models’ forecasting ability has been verified on a sample of historical data. A relative forecast error for 75% of observations has been in the range of (–25%; +37%). That result has been considered satisfactory. Subsequently, using those models, forecasts of unit costs and coal net output have been prepared for 220 longwalls planned for mining in the years 2020–2030. Those forecasts have been prepared in the stipulated ranges of geological and mining nuisance influencing mining process, by means of dedicated W Ue and W Ut factors. The nuisance models for forecasting purposes have been developed using the AHP (Analytic Hierarchy Process) method. The research hypothesis has been confirmed on the basis of the obtained results. An increase in the level of nuisance leads to an increase in the unit costs for longwalls and the deterioration of production results. Unit operating costs for longwalls in specific ranges of nuisance may differ by up to 30%, being in the range of 52.0–120.3 zł/Mg. Likewise, the coal daily output of longwalls may be even 22% lower, having the average level in the range of 1.89–3.61 thousand Mg/d.

The paper deals with the issue of financial efficiency, measured by the arithmetic rate of return, of indirect financial investments in the area of strategic raw materials (hard coal, copper, crude oil). Two forms of indirect investments were analyzed: shares of natural resources companies listed on the Warsaw Stock Exchange and futures contracts for strategic commodities: hard coal, copper and crude oil.

The time of the analysis is the first 6 months of 2019 and 2020. The year 2019 was regarded as an analysis of the period of economic growth, and the year 2020 was the analysis of the period of economic crisis. The comparisons were made in two dimensions. Firstly, it whether indirect commodity investments show the characteristics of efficiency resilience to the time of the economic crisis was checked (by comparing the achieved rates of return in the two analyzed periods). Secondly, which of the analyzed forms of investment (stocks, contracts) gives better investment results during economic growth and economic crisis was compared.

As it was shown in the paper, indirect commodity investments do not show an above-average rate of return neither during economic growth nor economic crisis. The achieved rates of return on shares compared to changes in the WIG20 index in the analyzed first half of 2019 were negative. Only one company showed a positive and significantly higher than the market rate of return. Very similar results were achieved by the analyzed companies in 2020.

On the other hand, the analysis of prices and rates of return on commodity futures contracts showed that in the period of economic growth it is effective to take a long position on crude oil contracts and a short position on hard coal contracts. In a period of economic crisis, the opposite position is profitable due to the observed growth in hard coal prices and a significant drop in crude oil prices.

The answers to the research questions posed in the paper do not provide indications for recommending indirect forms of investment in commodities as an alternative to analogous forms of other sectors of the economy. The analysis shows that the impact of the economic situation on the efficiency of commodity investment is most noticeable for crude oil, and the least (among the analyzed commodities) for indirect copper-based investments.

This paper researches the application of grey system theory in cost forecasting of the coal mine. The grey model (GM(1.1)) is widely used in forecasting in business and industrial systems with advantages of minimal data, a short time and little fluctuation. Also, the model fits exponentially with increasing data more precisely than other prediction techniques. However, the traditional GM(1.1) model suffers from the poor anti-interference ability. Aimed at the flaws of the conventional GM(1.1) model, this paper proposes a novel dynamic forecasting model with the theory of background value optimization and Fourier-series residual error correction based on the traditional GM(1.1) model. The new model applies the golden segmentation optimization method to optimize the background value and Fourier-series theory to extract periodic information in the grey forecasting model for correcting the residual error. In the proposed dynamic model, the newest data is gradually added while the oldest is removed from the original data sequence. To test the new model’s forecasting performance, it was applied to the prediction of unit costs in coal mining, and the results show that the prediction accuracy is improved compared with other grey forecasting models. The new model gives a MAPE & C value of 0.14% and 0.02, respectively, compared to 1.75% and 0.37 respectively for the traditional GM(1.1) model. Thus, the new GM(1.1) model proposed in this paper, with advantages of practical application and high accuracy, provides a new method for cost forecasting in coal mining, and then help decision makers to make more scientific decisions for the mining operation.

The energy obtained from biomass in the global balance of energy carriers is the largest source among all RES. It should be borne in mind that the share of biomass as an energy carrier in the total balance is as much as 14%. The basic sources of renewable energy used in Poland are the wind power industry and biomass. Organic chemical compounds are the source of chemical energy for biomass. The biomass can be used in a solid form (wood, straw) or after being converted to liquid (alcohol, bio-oil) or gas (biogas) form.

Pellets, meaning, the type of fuel of natural origin created from biomass compressed under high pressure without the participation of any chemical adhesive substances are recognized as the most common and available grades of biomass. Wood pellets manufactured from sawdust, shaving, or woodchips are the most popular type of pellets on the market. Fuel created in the form of granules is very dense and can be manufactured with low humidity content, which translates into an exceptionally high burn efficiency.

The authors of this article burned agro pellets from Miscanthus giganteus without additives and with solid catalyst and conducted a series of tests that determine the impact of boiler settings (blast power, time of feeding, chimney draft) on the process of burning fuel in real conditions. A solid catalyst was used to improve combustion conditions in one of the fuels. The catalyst burns carbon monoxide and reduces nitrogen oxides. The results in the form of observation of selected parameters are summarized in the table.

The paper investigates the supply structure of the capacity market in Poland in the coming years. The results of the capacity auctions conducted in 2018 are analyzed for this purpose. Three auctions were held at that time. The products traded in the capacity market are capacity obligations for the following years: 2021, 2022 and 2023. The auctions were organized in accordance with (i) he Act of December 8, 2017 on the Capacity Market and the (ii) Capacity Market Regulations published by the Polish Power Grid. The source of data used in this study is the official information of the President of the Energy Regulatory Office on the final results of the main auctions for 2021–2023 delivery periods. The list of the capacity suppliers who won capacity auctions contains the type of capacity market units, the volume of capacity obligations, the duration of capacity agreements and the business name of the capacity suppliers. The conducted analysis indicates that the auction for 2021 was won mainly by existing units (45.81%) and refurbishing units (33.51%). In subsequent years, the share of existing generating units is significantly higher and amounts to 91.67% for 2022 and 84.54% for 2023. The results of the study carried out in this paper also show that one energy company, being the owner of power generating daughter companies, has a very high share in these capacity auctions. The PGE Capital Group contracted 51.95% for 2021, 69.92% for 2022 and 64.44% for 2023 of the total capacity obligation. The volume amounts to over 70% of their total installed capacity.

The present paper describes the temporary language situation in Sweden. The country has a high rate of immigration and large minority groups have lived in Sweden for many hundreds of years. In order to reflect its cultural and language diversity Sweden has developed its own Language Law. This establishes Swedish as the main language in Sweden and declares five other languages to be national minority languages: Finnish, Meänkieli, Romani, Yiddish and Sami. Furthermore, the country’s language law protects and at the same time promotes Swedish Sign language. Swedish communes offer free Swedish courses for adult immigrants and immigrant children attend courses in Swedish as a Second Language both in primary and secondary school. Due to the multinational composition of Swedish suburbs a new variety of Swedish called rinkebysvenska has developed. This variety is characterized by many loan words from other languages, divergent pronunciation, morphology and syntax. Rinkebysvenska is used primarily by young immigrants living in Stockholm, Göteborg and Malmö and has assumed the status not only of a Sociolect, but also of a special Swedish slang. The mobility of Swedish inhabitants within the country has led to a smoothing out of Swedish dialects so that differences can only be observed in pronunciation. On the other hand, there is a strong tendency to protect and develop Övdalian – one of the dialects that differs most from Swedish.

This paper unpacks the legitimacy gap existing between post-communist policies of citizenship restitu-tion, the experiences of these policies, and the media coverage of these policies. Considering citizenship restitution first as analogous to property restitution, theoretically citizenship restitution appears as com-pensatory, to right the wrongs of communist- and Soviet-era seizures and border changes, and appears to establish citizenship restitution as a right. Using UK media coverage of Romania’s policy of citizen-ship restitution vis-à-vis Moldova, the paper shows the extent to which this policy is framed as an ille-gitimate loophole propagated by a ‘Romanian Other’ which is ‘giving out’ EU passports, exploited by an impoverished and criminal ‘Moldovan Other’, and inflicted on a ‘UK Self’ that is powerless to stem the tide of migration and block routes to gaining access to the EU via such policies. However, the paper also contrasts, and challenges, this media framing by using interviews with those acquiring Romanian citizenship in Moldova to demonstrate the extent to which acquiring Romanian citizenship in Moldova is a costly and lengthy procedure. Overall, the paper shows the extent to which citizenship restitution is a contested procedure, constructed as a right by the state seeking to compensate former citizens, and as illegitimate by those who construct a logic resulting from feeling threatened by policies of citizenship restitution.