Zuzana Szabova

Efficiency Rating of Vision in Terms of Prevention of Road Accidents at Work

The paper deals with determination of the medical fitness of drivers. They were psychologically tested with particular emphasis on visual perception. The research included visual perception - spatial vision and adapting to the darkness with the aim to show impact of age and education of the respondents to obtained results. The study included truck drivers, bus drivers and people with pre-test candidates and checking on driving instructors or examiners.

Study of Explosion Characteristics of Wood Dust Clouds in Dependence of the Particle Size Distribution

Abstract The article deals with the measurement of explosion characteristics of wood dust. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds and the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds. On the basis of measurements, we found that the distribution of the particles has a significant impact on the parameters of wood dust samples.

Determination of the Explosion Characteristics of Wheat Flour

Abstract The article deals with the measurement of explosion characteristics of wheat flour. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds, the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds and LEL according to STN EN 14034-3+A1:2011 Determination of explosion characteristics of dust clouds: Determination of the lower explosion limit LEL of dust clouds. The testing of explosions of wheat flour dust clouds showed that the maximum value of the pressure was reached at the concentrations of 600 g/m3 and its value is 8.32 bar/s. The fastest increase of pressure was observed at the concentration of 750 g/m3 and its value was 54.2 bar/s.

Study of Metalworking Fluids Biodegradability Potential Enhancement by the Prior Application of Ozone

The increases in biological mineralization of selected Metalworking fluids (MWF) pre-treated by ozone were investigated. There were studied 11 different fluids four of emulsion types, four of semi-synthetics and three of synthetic types. Expectations according to the literature review that the pre-treatment enhance the biodegradability of the metalworking fluids were not confirmed in 7 samples. Only 4 samples achieved after ozone pre-treatment better biological degradation. Enhanced biodegradability level after ozone pre-treatment step was observed in three emulsions (Samples 1, 2 and 3) and one semi-synthetics (Sample 7). While nontreated soluble oils reached biodegradability level from 45 to 73 %, after 1 hour of ozone treatment the biodegradability increased from 65 to 82 %. Semisynthetic metalworking fluid without any treatment reached 56 % of the biodegradability level. After one hour of ozone application increased the biodegradability level to 74 % and after 2 hours to 82 %. During ozone treatment it was observed the destabilization of emulsions in half of tested samples.

Determination of fire and explosion characteristics of dust

Abstract The aim of this paper is to approximate danger of dust clouds normally occur by determining their explosion characteristics. Nowadays, dusty environment is phenomenon in the industry. In general, about 70% of dust produced is explosive. Dust reduction in companies is the main purpose of the national and European legislative. Early identification and characterization of dust in companies may reduce the risk of explosion. It could be used to identify hazards in industrial production where an explosive dust is produced. For this purpose several standards for identification and characterization of explosion characteristics of industrial dust are being used.

Development of the Hexagonal Structure in the Processes of Improving Vibration Insulating Properties of Products

This paper deals with noise and mechanical vibration reduction by optimization and proper application of the hexagonal cell structure formed on the surface of oscillating bodies. This structure can be applied in a broad spectrum of products like home appliances, industrial machines and devices, drives etc. It stems from the knowledge of the area of human health protection against the negative effects of noise and vibrations as well as psychological comfort, performance and optimization of psychoacoustic perceptions. The authors present the design of a suitable parametric model which makes it possible to change the basic structure parameters and by means of numerical simulations approach the achievement of optimal structure parameters.

Effect of Ozone Application to Microbial Contaminated Samples of In-Use Metalworking Fluids

Metalworking fluids are prone to bacterial contamination during the operational time. They are unwanted due their impact on the quality of the fluid, health impact of the microbial toxins, pathogens and degradation products of fluid. Typically bacteria are eliminating by the adding of biocides, which could be also harmless to operators health. Ozone is used as a sterilizing agent in many industrial applications, mostly in water disinfection. Wide varieties of microorganisms can be treated by the ozone. Ozone, a powerful disinfectant, is very efficient to inactivate resistant microorganisms under low concentration and short contact time. We studied the application of ozone to sterilize two types of metalworking fluids (synthetic and emulsion) with avoiding of oxidation power of ·OH radicals which are generated during ozonation process.

Preliminary Study of Ozone Utilization in Elimination of Bacterial Contamination in Metalworking Fluids

Metalworking fluids (MWFs) are used during machining to prolong the life of the tool, carry away debris, and protect the surfaces of work pieces. During their lifetime they are prone to intensive microbial deterioration. Microbial contamination can be a problem, primarily because of potentional adverse effect to the operators health and effect on a fluid quality, performance and economics. Bactericides are added to control the growth of micro-organisms. The paper deals with possible utilization of ozone for sterilization of MWFs to avoid presence of biocides. There were tested 16 MWFs for their reaction to ozone application in extreme conditions (concentration of MWF 1% (v/v), ozone concentration 15 g hour-1, application of ozone 4 hours). After, was realized pilot sanitation of selected in-use MWF for elimination of presence bacterias by applying lower concentration of O3, there were measured few parameters to control the quality of treatment fluid.

The Effect of External Conditions on Ignition Temperature of Thermoplastic Polyurethane Elastomers

The paper reports a study of the impact of moisture and age of pellets, as well as an external condition, on the thermal degradation of the thermoplastic polyurethane elastomers. Because thermoplastic polyurethane elastomers are hydroscopic polymer, moisture will have a significant impact on thermal degradation. For determination of the effect of moisture and age were used the thermo gravimetric analysis, differential scanning calorimeter and ISO STN 871: Plastics. Determination of ignition temperature using a hot-air furnace.

Potential Utilization of OECD 302 B Test in Biodegradability Assessment of Metalworking Fluids

The main aim of this study was to evaluate the ability of the activated sludge from sewage treatment plant to degrade a part of the 12 randomly selected metalworking fluids (MWFs) according to OECD 302B (with different addition of activated sludge AS 0.25 g/l, 0.50 g/l and 1.00 g/l of suspended solids - SS). The degradability test showed that, after the first 3 hours of cultivating, adsorption grew with the increasing amount of inoculums. In the case of AS addition 1.00 g/l of SS were the adsorption rate lower than 20 % in four samples, in the case of AS addition 0.50 g/l of SS in 9 samples and in the case of AS addition 0.25 g/l of SS in all 12 tested samples. In four samples were also observed the lag phase (adaptation of the bacterias to the presented carbon source). If occur adsorption rate more than 20% it is probably impossible to distinguish biological degradation of organic matter from abiotic elimination from the suspension.