To realize a structure which can be conveniently tuned to multiple and wideband frequency ranges, a geometrical-stiffening membrane acoustic metamaterial (MAM) with individually tunable multiple frequencies is presented. The MAM is realized by a stacked arrangement of two membrane-magnet elements, each of which has a membrane with a small piece of steel attached in the centre. It can be tuned individually by adjusting the position of its compact magnet. The normal incidence sound transmission loss of the MAM is investigated in detail by measurements in an impedance tube. The test sample results demonstrate that this structure can easily achieve a transmission loss with two peaks which can be shifted individually in a wide low-frequency range. A theoretical consideration is analysed, the analysis shows that the magnetic effect related to this distance leads to a nonlinear attractive force and, consequently, nonlinear geometrical stiffening in each membrane-magnet element, which allows the peaks to be shifted. A reasonable design can make the structure have a good application prospect for low-frequency noise insulation where there is a need to adjust the transmission loss according to the spectrum of the noise source.

In nuclear facilities, the reading of the sensors is very important in the assessments of the system state. The existence of an abnormal state could be caused by a failure in the sensor itself instead of a failure in the system. So, being unable to identify the main cause of the “abnormal state” and take proper actions may end in unnecessary shutdown for the nuclear facility that may have expensive economic consequences. That is why, it is extremely important for a supervision and control system to identify the case where the failure in the sensor is the main cause for the existence of an abnormal state. In this paper, a system based on a wireless sensor network is proposed to monitor the radiation levels around and inside a nuclear facility. A new approach for validating the sensor readings is proposed and investigated using the Castalia simulator.

The measurement of SO2, and fluorine compounds concentrations in the air at 8 points on the King George Island, South Shetland Islands, were done in January and February 1979. The received values were similar to the ones for regions recognized as the world background areas. The activity of the Polish Antarctic Station did not influence the air pollution status neither in its surroundings, nor in penguins colonies and extinct volcano areas on Penguin Island.

The article presents possible ways of development of decision-making processes in autonomous vehicles. The highest degree of autonomy means that it is not the driver but the system, machine or artificial intelligence that makes decisions about road activities. The total autonomy of vehicles gives them predictability, limits the number of accidents they cause, but also highlights the need to develop an ethical system that artificial intelligence will be able to refer to in a critical situation. It is not possible to foresee all the situations that will occur on the roads, so it is necessary to create robot- -human rights that will be a new and binding kind of decalogue. The key issue is that robotic-human rights should be universal, transparent and really applicable to everyone, otherwise there will be chaos on the road and the expected decrease of the number of accidents due to the introduction of autonomous vehicles will not come to pass.