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The paper deals with basic research of vibration generated at abrasive waterjet cutting of materials and their analysis of frequency spectrum in the plane cut. As an experimental material, stainless steel AISI 309 has been used. Experimentally controlled factor involved in the experiment was abrasive mass flow rate with values m a = 250 and 400 g min −1 at a constant traverse speed v= 100 mm min −1 . The vibrations were recorded during experimental cutting by sensors PCB IMI type 607A11 placed on experimental material along the cut at a distance of 50 mm from the cutting plane. Data collection was carried by NI PXI measurement system and frequency analyzer Microlog GX-S. Signal was evaluated by virtual instrument created in the object-programming environment LabView 8.5. Various sizes of amplitudes were observed depending on the distance of abrasive waterjet cutting process from the beginning of the cut. Two peaks of frequency bands have been also found: the first between 500 and 600 Hz and the other at approximately 12.5 kHz. Using this method is possible to ensure the determination of technology efficiency of the material removal process.

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The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ), especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ.

The development and application of new materials brings, in connection with their technological machining, a number of new questions. Classical methods of machining are supplemented by new technologies. An abrasive water jet represents a universal flexible tool enabling the machining of all natural and artificial materials that are not damaged by direct contact with water. Great attention is paid to the study of the cut surface topography after abrasive water jet machining. The study of surface topography is important from the point of view of modelling and prediction of the topographic function of the abrasive water jet. On the basis of knowledge of the topographic function, we are able to optimise the technological parameters of the abrasive water jet machining process, which has an impact on the output, quality and price of the final product. The mechanism to remove material is an area which has not received much attention. In material disintegration, the mechanisms of cutting, plastic deformation, fatigue and fracture participate physically. By studying the surface topography we can better understand the process of abrasive water jet machining, specify the theory and correctly quantify the mechanism of material removal, which is the subject of this paper.

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Medical errors negatively affect patients, healthcare professionals, and healthcare establishments. Therefore, all healthcare service members should be attentive to medical errors. Research has revealed that most medical errors are caused by the system, rather than individuals. In this context, guaranteeing patient safety and preventing medical faults appear to be basic elements of quality in healthcare services. Healthcare institutions can create internal regulations and follow-up plans for patient safety. While this is beneficial for the dissemination of patient safety culture, it poses difficulties in terms of auditing. On the other hand, the lack of a standard patient safety management system, has led to great variation in the quality of the provided service among hospitals. Therefore, this study aims to create an index system to create a standard system for patient safety by classifying medical errors. Due to the complex nature of healthcare and its processes, interval-valued intuitionistic fuzzy logic is used in the proposed index system. Medical errors are prioritized, based on the index scores that are generated by the proposed model. Because of this systematic study, not only can the awareness of patient safety perception be increased in health institutions, but their present situation can also be displayed, on the basis of each indicator. It is expected that the outcomes of this study will motivate institutions to identify and prioritize their future improvements in the patient safety context.