It is well-known that the high-performance polymeric dielectric films used for high-voltage DC capacitors should have outstanding capabilities in terms of electrical and mechanical properties in order to face harsh operating conditions. Many factors limit the ability of these thin films to face different and growing stresses according to modern electrical requirements. Microstructure properties, additives, impurities, defects formed during manufacturing as well as applied stress types significantly affect the performance of dielectric films and their operational lifetime. This paper presents a comprehensive review of the factors which affect the ageing, degradation and breakdown of metallised polypropylene (PP) capacitors films. The effects of microstructure, surface morphological properties, mechanical properties and defects on the reliability of biaxially oriented polypropylene films (BOPP) are studied. In addition, the phenomena affecting dielectric performance and ageing mechanisms which are induced by electrical, thermal and electrothermal stresses are discussed.

Applications for document similarity detection are widespread in diverse communities, including institutions and corporations. However, currently available detection systems fail to take into account the private nature of material or documents that have been outsourced to remote servers. None of the existing solutions can be described as lightweight techniques that are compatible with lightweight client implementation, and this deficiency can limit the effectiveness of these systems. For instance, the discovery of similarity between two conferences or journals must maintain the privacy of the submitted papers in a lightweight manner to ensure that the security and application requirements for limited-resource devices are fulfilled. This paper considers the problem of lightweight similarity detection between document sets while preserving the privacy of the material. The proposed solution permits documents to be compared without disclosing the content to untrusted servers. The fingerprint set for each document is determined in an efficient manner, also developing an inverted index that uses the whole set of fingerprints. Before being uploaded to the untrusted server, this index is secured by the Paillier cryptosystem. This study develops a secure, yet efficient method for scalable encrypted document comparison. To evaluate the computational performance of this method, this paper carries out several comparative assessments against other major approaches.

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This paper discusses the stabilising problems of a nonlinear and multivariate underactuated systems, also known as Inverted Pendulum (IP) systems. The attitude control of a nonlinear IP system is thus considered. One of the most important techniques, a Linear Quadratic Regulator (LQR), is used in this paper to design a controller for an IP system. The structure of LQR parameters is based on weight matrices, and the adjustment of the weight matrices parameters is the most challenging part of this, being normally computed by repeating trials and adjusting based on successful or unsuccessful outcomes. The difficulty in guessing the optimum matrices and achieving automatic adjustment of the weighting matrices is mitigated by the introduction of a metaheuristic algorithm to investigate the optimal solution; this is based on a swarm of particles moving in a virtual space. The proposed approach successfully stabilised the IP system in the upright position and removed perturbations; the simulated results thus showed satisfactory performance of the suggested control method.

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