Stanislav Škapa

Techno-economic considerations: turning fermentation residues into lightweight concrete

ABSTRACT To divert from fossil fuels, nearly 20 k of biogas plants have been built in Europe over the past two decades. Although this trend is not closely followed in the rest of the world, it is still represented by other tens of thousands of installations. Since average biogas plant produces some 10 k tones of fermentation residues (hereinafter referred to as FR) annually, many managers and engineers are intensively looking for an economically efficient way to handle this waste. Under the new solution, FRs were pyrolyzed using waste heat from the biogas combustion engine. The obtained charred FRs (hereinafter as CFR) were incorporated in concrete at various dosages. It was revealed that up to a weight ratio of approximately 20%, concrete density decreases without its mechanical properties being degraded. Since the CFR are nowadays highly economical, the above-stated method represents an environmentally friendly and also financially promising solution that is, to our best of our knowledge, the most important contribution of this work.

Fuzzy Clustering and Loan Risk Prediction

Fuzzy logic has had successful applications in risk management. There are different methods used as a support for risk decision making. The article deals with the fundamentals of fuzzy clustering method. The case study of the use of this method is presented on the loan risk prediction. The risk prediction plays an important role nowadays.

Commodities as a Tool of Risk Diversification

Investing in commodities has become a new topic for private investors in recent years. Private investors are trying to spread their investments across a much wider spectrum of investments than in the past. They are looking for new sources of return and better diversification of investment risk. In this process, they are searching beyond the traditional asset classes of equities, bonds, cash and real estate. The objective of the paper is to critically explore the possibility of investing in commodities mainly for private investors and analyses investment characteristics. The main scientific aim is to use a complex of more sophisticated and theoretically advanced statistical techniques and apply them on the findings. This paper will provide comprehensive analyses of mostly used commodity indexes of 1st generation and describe main differences between 1st and 2nd generation of commodity indexes and some examples of rollover mechanism will be critically explain. A representative of 2nd generation of commodity indexes was chosen for comprehensive data analysis to another asset class and for the testing whether commodities decreasing a risk of investment portfolio. ©