For the safe operation of a hydrogen-powered car, one of the strategic requirements is to design the drive chain so that it is burdened with the least possible risk. At the same time, in order to be able to use it in normal operation, it is necessary to create a risk management system throughout the life of the car so that risks are minimized to the level of their acceptability not only by customers but also by a comprehensive infrastructure during its technical life. Experience has shown that one of the decisive risks in the operation of a hydrogen-powered car is the leakage of hydrogen from the car’s fuel system. The article analyzes the pressure effects on obstacles in the explosion of 1 m3 of a stoichiometric mixture of hydrogen and air. The analysis of the instantaneous pressures as a function of time describes the possible consequences for the human body and the surrounding objects with regard to the distance from the center of the explosion.
The paper deals with the minimachine designed to move within the pipes with inner diameter less than 25 mm. The minimachine consists of two modules connected by a link of variable length enabling to change their mutual distance. Motion is based on inchworm principle known from biology. In motion sequence one of the modules is anchored to the inner surface of the pipe, while the second is released and moved forward by change of the link length. The principle of the link length change consists in transformation of the actuator rotary movement to the linear motion. Problem of anchoring the modules by flexible metal bristles is analyzed in the paper.
INTRODUCTIONNowadays the mobile machines for motion within pipes represent a promising area of Vladimír IVANČO (SK)
Measurements of solid aerosol concentrations are important tools to monitor air conditions at the workplace. In particular, the requirement for the workplace air quality management is necessary to prevent health damage and occupational diseases in exposed jobs. In this case, exceeded limit values for the concentration of solid aerosols were measured for all exposed workers. If such concentrations persist, workers' health may be at risk and occupational diseases may occur after prolonged exposure.
Fire safety of road tunnels depends on quick identification of a developing fire and its location. Current systems, which are based on the principle of direct temperature sensing, do not identify a fire before its second stage. The paper suggests the possibility of utilizing the principle of the Curie temperature for identification of increased temperatures resulting from a developing fire in road tunnels. The proposed temperature sensor can complement the existing fire protection system for tunnels and increase its effectiveness.
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