Wireless sensors are an irreplaceable link in the chain of global networking today. There is almost no area of human activity where they are still not used, and they will be used in the near future almost everywhere. Wireless sensor networks consist of a large number of sensor nodes that are arranged (usually randomly) in an area. The main problem is the limited power supply. Sensors are usually powered by the battery which is not possible to replace. The lifetime of the network depends on the duration of battery power of sensor nodes. The largest part of the consumed energy goes for communication with the rest of the network. Therefore, the selection of good routing protocol is essential for the long life-span of the network. There are a large number of proposed protocols and they can be divided into several groups, depending on the approach to the problem. In this paper we present a family of hierarchical protocols, their common features and specific implementation, we will present advantages and disadvantages as well as possible directions of further development.
The availability of real-time data on the state of railway facilities and the state-of-the art technologies for data collection and analysis allow transition to the fourth generation maintenance. It is based on the prediction of the facility functional safety and dependability and the risk-oriented facility management. The article describes an approach to assessing the risks of hazardous facility failures using the latest digital data processing methods. The implementation of this approach will help set maintenance objectives and contribute to the efficient use of resources and the reduction of railway facility managers’ expenditures.
The availability of real-time data on the state of railway facilities and the state-of-the art technologies for data collection and analysis allow transition to the fourth generation maintenance. It is based on the prediction of the facility functional safety and dependability and the risk-oriented facility management. The article describes an approach to assessing the risks of hazardous facility failures using the latest digital data processing methods. The implementation of this approach will help set maintenance objectives and contribute to the efficient use of resources and the reduction of railway facility managers’ expenditures.
