Karol Basiński, Bartłomiej Ufnalski and Lech M. Grzesiak
A hybrid maximum power point tracking method has been proposed for the photovoltaic system using a stochastic evolutionary search and a deterministic hill climbing algorithm. The proposed approach employs the particle swarm optimizer (PSO) to solve a dynamic optimization problem related to the control task in a PV system. The position of the best particle is updated by the hill climbing algorithm, and the position of the rest of the particles by the classic PSO rule. The presented method uses the re-randomization mechanism, which places five consecutive particles randomly, but in specified intervals. This mechanism helps track the maximum power point under partially shaded conditions.
Probability Density Functions of Voltage Sags Measured Indices
Voltage sags can cause interruptions of industrial processes, which could result as a malfunction of equipment and considerable economic losses. Thus, it is very useful to see certain rules of voltage sags occurrence due to duration and depth.
This paper presents statistical analyses of voltage sags in several domestic and industrial transformer stations. Voltage sag probability functions are calculated from actual measurement data, by means of a hill climbing algorithm. Lognormal and Weibull frequency distribution functions are used to describe distribution of measured voltage dips.
The most commonly used methods for solving classical (historical) ciphers are based on global optimization (meta-heuristic methods). Despite the fact that global optimization is a well-studied problem, in the case of classical ciphers, there are still many open questions such as the construction of fitness functions or efficient transformation of the cryptanalysis (breaking attempt) to an optimization problem. Therefore the transformation of a cryptanalytical task to an optimization problem and the choice of a suitable fitness function form an important part of the topic. In this paper, we focus on the simple columnar transposition in depth. Our main contribution is a detailed analysis and comparison of different fitness functions, fitness landscape analysis and solving experiments.
The algorithm for maximum power point tracking (MPPT) using a fixed is widely used because of its simplicity and easyness to implement. This paper presents an improvement consisting in a variable step (VS) applied to the standard Hill Climbing MPPT technique to improve both accuracy and tracking speed. Drawbacks will still be encountered in VS tracking algorithms, between response time and power oscillation.
Improving output parameters of the Mazda B6 combustion engine from the vehicle Mazda 323 for amateur "hill climb" and "rally" competitions has been analysed. Tuning of such an engine for sport competitions means the optimisation of its parameters at the lowest possible economic costs, within the revolution range 4000 - 6000 min-1, where the engine during competition works most often. With the help of the program Lotus Engine Simulations, the construction of the exhaust manifold has been optimised, together with valve timing and other adjustments, listed in the work, on output parameters of the engine. The optimum combinations of parameters were experimentally verified on a chassis dynamometer. Final adaptations have led within the previously specified range of revolutions to an improvement between 5 and 22% in power and torque.
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Andrzej Lewandowski, Marcin Kowalewski, Tomasz Kowalik and Zuzanna Piekorz
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