Maurilio Pereira Coutinho

The Influence of Time and Cement Type on Push-Out Bond Strength of Fiber Posts to Root Dentin

The bond strength of fiber posts luted with resin cements was evaluated after two storage times in different regions of a post space. A total of 40 single-rooted human teeth were endodontically treated and prepared for cementation of fiber posts (White Post DC). In groups 1 and 3 (G1 and G3, respectively), posts were luted with RelyX ARC, whereas the posts in groups 2 and 4 (G2 and G4, respectively) were luted with RelyX Unicem. After one month of storage at 100% humidity, G1 and G2 were transversally sectioned in 1.7-mm slices of the cervical (C), middle (M), and apical (A) thirds of the post space and submitted to push-out testing at 1 mm/min. After nine months of storage, the roots of G3 and G4 underwent the same process. Mean values were analyzed using the Mann-Whitney and Kruskal-Wallis tests (α=0.05). The bond strengths in G2 (C=4.26±2.29; M=4.67±3.54; A=7.27±4.30) were statistically higher than in G1 (C=3.81±1.07; M=1.57±1.62; A=1.99±1.60) in the middle and apical thirds (p=0.001). Bond strengths in G4 (C=3.36±1.39; M=4.49±2.17; A=3.83±1.92) were higher than in G3 (C=2.13±0.47; M=0.94±1.05; A=0.95±1.02) in all evaluated regions (p=0.02, p<0.001, and p<0.001, respectively). When comparing the root regions for each group, G1 had higher values in the cervical third than the middle third (p=0.02). The self-adhesive resin cement showed better results than the conventional resin cement at both storage times. For both materials a similar performance among the three root regions was found. Storage time did not influence the shear bond strength.

Anomaly detection in power system control center critical infrastructures using rough classification algorithm

Power System Control Centers are moving toward distributed and decentralized operations. The use of information technology (IT) to achieve these goals produces vulnerabilities and security threats. To safeguard against the threat of cyber-attacks, service providers also need to maintain the accuracy, assurance and integrity of their interdependent data networks. This paper presents the results of the Anomaly Detection technique using Rough Sets Classification Algorithm for improving the security of Power System Control Centers in the Electric Power System Critical Infrastructure. The methodology presented can be used to identify attacks and failures and, also, for improving the confidence of the state estimation process. A test environment is implemented and the results for a 6 bus electrical power system are presented.

Particle Swarm Optimization applied to system restoration

The electrical power system restoration after an incident is a complex process involving decision-making problems of combinatory nature. In this case, the operator support systems play an important role in a performance of this process. This paper introduces a decision support tool based on Particle Swarm Optimization Technique (PSO). The technique is based on the change of system functional configuration and consists in the use of the maximization of power demand supplied and minimization of the number switched lines. This technique also avoids the overload of system lines. A case study is introduced.

Particle Swarm Optimization Applied to Restoration of Electrical Energy Distribution Systems

This paper presents a technical application of the Particule Swarm Optimization - PSO technique to a reconfiguration problem of a electrical energy distribution system. The proposed methodology consists of the use of the maximization function of the number of loads supplied and the loss minimization by the expansion of the original PSO. The approach utilized the Distribution_System_01. A number of tests were carried out in the system to simulate several fault occurrences in the electrical energy transmission lines. The PSO algorithm encountered the optimal solution in a reasonable CPU time, compared to the dimension of the distribution system.

A Methodology to Extract Rules to Identify Attacks in Power System Critical Infrastructure

This paper presented an alternative technique to improve the security of electric power control systems by using anomaly detection to identify attacks and faults. By using rough sets classification algorithm, a set of rules can be defined. The alternative approach tries to reduce the number of input variables and the number of examples, offering a more compact set of examples in order to fix the rules to the anomaly detection process. An illustrative example is presented.

Attack and Fault Identification in Electric Power Control Systems: An Approach to Improve the Security

This paper presented a technique to extract rules in order to identify attacks and faults to improve security of electric power control systems. By using rough sets classification algorithm, a set of rules can be defined. The approach tries to reduce the number of input variables and the number of examples, offering a more compact set of examples to fix the rules to the anomaly detector. An illustrative example is presented.

New technology applied to a restoration of electrical power substation

This paper presents a new approach based on a connection of two techniques applied in Artificial Intelligence to solve problems of restoration of electrical power substations. The techniques are: the Four-valued Annotated Paraconsistent Logic — 4vAPL and the Case-based Reasoning — CBR. This linking process happens in the manipulation of the functions of belief, disbelief, expertise and temporality of the 4vAPL for the recovery of cases to determine process diagnostics of a CBR. The 4vAPL is the support applied to the problems that present inconsistent, partial, undefined information. The domain of CBR is applied in the restoration of an electrical power substation. Thus, it approaches the system under study to real situations.

Comparison between PSO and GA in System Restoration Solution

The use of the Evolutionary Computation (EC) grew in interest recently. Among various Evolutionary Computation approaches, Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) are used in optimization problems; they have much in common but also have some differences. This paper presents a decision support tool based on Particle Swarm Optimization Technique (PSO) and Genetic Algorithm Technique (GA). This tool is applied to electrical power system restoration after an incident. The operator support systems play an important role in a performance of the complex process involving decision-making problems of combinatory nature. The techniques are based on the change of system functional configuration and consist in the use of the maximization of power demand supplied and minimization of the number switched lines. These techniques also avoid the overload of system lines. A case study is introduced.

Detecting Attacks in Electric Power System Critical Infrastructure Using Rough Classifi cation Algorithm

This paper presents an alternative technique for improving the security of Electric Power Control Systems by implementing anomaly detection methods to identify attacks and faults. By using Rough Sets Classifi cation Algorithm, a set of rules can be defi ned. The alternative approach tries to reduce the number of input variables and the number of examples, offering a more compact set of examples to fi x the rules to the anomaly detection process. An illustrative example is presented.

Different types of grammar: Possible applications to smart-grids

The first step in a integration processing or for any type of computational program is to know the grammar used by the equipment to be integrated or that will receive the developed program. The same occurs when it is important to extract information in a data mining process into a database produced by equipment or a system. Also, during the integrated operation of several types of equipment in smart-grids, it is fundamental to know very well each different grammar to obtain a correct integration. This objective of this paper is presented four examples of different types of grammar used in different type of applications in control centers and substations.