One of the most important challenges in the design of the piezoelectric energy harvester is its narrow bandwidth. Most of the input vibration sources are exposed to frequency variation during their operation. The piezoelectric energy harvester’s narrow bandwidth makes it difficult for the harvester to track the variations of the input vibration source frequency. Thus, the harvester’s output power and overall performance is expected to decline from the designed value. This current study aims to solve the problem of the piezoelectric energy harvester’s narrow bandwidth. The main objective is to achieve bandwidth broadening which is carried out by segmenting the piezoelectric material of the energy harvester into n segments; where n could be more than one. Three arrays with two, four, and six beams are shaped with two piezoelectric segments. The effect of changing the length of the piezoelectric material segment on the resonant frequency, output power, and bandwidth, as well as the frequency response is investigated. The proposed piezoelectric energy harvesters were implemented utilizing a finite element method (FEM) simulation in a MATLAB environment. The results show that increasing the number of array beams increases the output power and bandwidth. For the three-beam arrays, at n equals 2, 6 mW output power and a 9 Hz bandwidth were obtained. Moreover, the bandwidth of such arrays covered around 5% deviation from its resonant frequency. All structures were designed to operate as a steel wheel safety sensor which could be used in train tracks.

Blockchain is a shared decentralized database. Distributed among a network of nodes, the term distributed ledger technology (DLT) is also used to describe a system in which transactions are recorded from multiple places at the same time (on different nodes in the network) without a central data store. Blockchain is an advanced product that stores data securely and reliably on the network, and several researchers in the field of blockchain, have expanded the capabilities and capabilities of the Bitcoin blockchain technology with the spread of the Ethereum blockchain platform, which added the capabilities of smart contracts to Bitcoin, smart contracts are Self-executing agreements are tokenized within the blockchain in the same way that users exchange bitcoins. Contracts are "smart" because they can carry out obligations without the intervention of a third party. In this research, we address the governance of the blockchain by defining the term governance, its use and types.

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