Chronic stress is the main cause of health problems in high-risk jobs. Wearable sensors can become an ecologically valid method of stress level assessment in real-life applications. We sought to determine a non-invasive technique for objective stress monitoring. Data were collected from firefighters during 24-h shifts using sensor belts equipped with a dry-lead electrocardiograph (ECG) and a three-axial accelerometer. Levels of stress experienced during fire incidents were evaluated via a brief self-assessment questionnaire. Types of physical activity were distinguished basing on accelerometer readings, and heart rate variability (HRV) time series were segmented accordingly into corresponding fragments. Those segments were classified as stress/no-stress conditions. Receiver Operating Characteristic (ROC) analysis showed true positive classification as stress condition for 15% of incidents (while maintaining almost zero False Positive Rate), which parallels the amount of truly stressful incidents reported in the questionnaires. These results show a firm correspondence between the perceived stress level and physiological data. Psychophysiological measurements are reliable indicators of stress even in ecological settings and appear promising for chronic stress monitoring in high-risk jobs, such as firefighting.

The purpose of the work is to determine the possibility of using waste from waste heat-resistant cullet as a filler in concrete composites. The article discusses the results of testing selected performance properties of the designed concrete composite. The samples were tested for mechanical properties: compressive strength, impact resistance. Research also included identifying structural changes in the designed composite.

This study aimed to evaluate the mass concentration of size-resolved (PM1, PM2.5, PM4, PM10, PM100) particulate matter (PM) in the Wieliczka Salt Mine located in southern Poland, compare them with the concentrations of the same PM fractions in the atmospheric air, and estimate the dose of dry salt aerosol inhaled by the mine visitors. Measurements were conducted for 2 hours a day, simultaneously inside (tourist route, passage to the health resort, health resort) and outside the mine (duty-room), for three days in the summer of 2017 using DustTrak DRX devices (optical method). The highest average PM concentrations were recorded on the tourist route (54–81 µg/m3), while the lowest was in the passage to the health resort (49–62 µg/m3). At the same time, the mean outdoor PM concentrations were 14–20 µg/m3. Fine particles constituting the majority of PM mass (68–80%) in the mine originated from internal sources, while the presence of coarse particles was associated with tourist traffic. High PM deposition factors in the respiratory tract of children and adults estimated for particular mine chambers (0.58–0.70), the predominance of respirable particles in PM mass, and the high content of NaCl in PM composition indicate high health benefits for mine visitors.

The article presents the results of an investigation of water composition and quality in sprinkler installations, as well as the influence of temperature changes on the corrosion process. The physical and chemical components of the water were measured to ascertain the influence of its properties on the corrosion process in a wet pipe sprinkler system operating in significantly changing ambient temperature conditions. The article presents the results of measurements of the wall thickness of galvanized pipes and changes in the chemical composition of water occurring under the influence of variable ambient temperature. The range and variability of temperatures corresponded to the seasons of the year: spring and summer in a temperate climate. Changes in the corrosive aggressiveness of water were assessed using the Langelier saturation index (LSI), the Ryznar stability index (RSI), and the general acidity intensity index (I). The tests revealed that the tap water used demonstrated strong corrosive properties for galvanized pipes. The calculated indices showed the tendency of water to cause corrosion (−1.1 > LSI < 1.0; RSI = 7.1–12.8). The chemical parameters that significantly influenced the corrosion of galvanized pipes are chloride (Cl−), sulphate (SO42−), and bicarbonate (HCO3−) ions. An important factor contributing to the intensification of corrosion is the roughness and heterogeneity of the pipe surface.

Water supply systems are complex engineering structures; certainly, the most important part is the water distribution network. The design of this element requires calculations and many analyses to arrive at the best solution. The main task of the calculation is to determine the flow rates through pipes, to determine pressure losses, height of tanks, pressure required in the supply pumping station, pressure levels in the individual nodes of the network. Correct execution of the calculations requires careful evaluation of the results obtained and accuracy in the solutions applied. The issue of controlling the results of calculations is difficult to present in algorithmic form as these are mainly based on the experience and knowledge of the designer. Classes of decisions describing the problems of pressure loss in the pipework were established in order to evaluate the results of calculations. Numerical experiments were carried out in this paper to show how the 'K-nearest neighbour' method can be used to evaluate pressure loss in water pipes.