The deterioration of the technical condition of plant equipment is a common phenomenon today. This is increasingly contributing to breakdowns and accidents, according to the experience of national and international authorities. Plants that are operating with an inadequate maintenance strategy are nowadays approaching the end of their design life and thus represent an increased risk of accidents. Ageing processes are often accelerated by operators' underestimation of the effects of stresses and strains on equipment and the extent of degradation mechanisms, and consequently by inadequate design and operation of condition monitoring and maintenance procedures. The aim of our work is to investigate domestic and foreign trends in the light of modern maintenance optimization methods and to make related recommendations for optimizing maintenance scheduling for domestic employers.

The study examines the suitability of a new analytical method that can provide reliable results to end users during geothermal investments. The use of individual risks, influencing factors, and evidence with appropriate complexity can support sound, considered decisions. In the research work, we investigated the reopening potential of three barren wells for heat recovery in a sample area in north-eastern Hungary using Bayesian probability-based nets. In our model, the replacement of current fossil energy use with geothermal energy was simulated, the effect of which was expressed in tonnes of CO2 emissions saved. Our studies confirmed the suitability of reopening and geothermal utilization of low-enthalpy infertile wells.

During their application, behavior of nanomaterials can differ from the generally known, widely applied, considering their risks, familiar, legislated materials. Since they gained importance rapidly, we did not have enough time to study the mechanism of action of these materials in details. The short- and long-term effects of these materials are only scarcely known or not known. However, since the middle of the 2000s decade, an increasing trend can be noticed regarding the scientific literature dealing with the risk assessment of nanomaterials. It is important to pay special attention to the full life-cycle of the nanomaterials and to know the short- and long-term effects of some processes like mining, production, application, deposition, neutralization on our environment and on the health and security of the directly or indirectly affected people. In our paper we examine in detail the effects which can have an effect on human health and safety during the application of nanomaterials. We summarized the collected parameters to be tested, and we cathegorized them into topic areas in order to give assistance in the preparation risk assessments associated with nanomaterials, thus even the laymen can have a good overview on the critical factors in aspects of human health.