Ahmad Asrul Ibrahim

Lightning search algorithm

Totally new optimization method inspired by lightning phenomena is introduced.The concept of projectiles and channel forking is adopted for movement of step leaders.Three types of projectiles are modeled as search mechanisms of LSA.The result of the LSA provides better results compared with the other tested methods. This paper introduces a novel metaheuristic optimization method called the lightning search algorithm (LSA) to solve constraint optimization problems. It is based on the natural phenomenon of lightning and the mechanism of step leader propagation using the concept of fast particles known as projectiles. Three projectile types are developed to represent the transition projectiles that create the first step leader population, the space projectiles that attempt to become the leader, and the lead projectile that represent the projectile fired from best positioned step leader. In contrast to that of the counterparts of the LSA, the major exploration feature of the proposed algorithm is modeled using the exponential random behavior of space projectile and the concurrent formation of two leader tips at fork points using opposition theory. To evaluate the reliability and efficiency of the proposed algorithm, the LSA is tested using a well-utilized set of 24 benchmark functions with various characteristics necessary to evaluate a new algorithm. An extensive comparative study with four other well-known methods is conducted to validate and compare the performance of the LSA. The result demonstrates that the LSA generally provides better results compared with the other tested methods with a high convergence rate.

Effect of maternal methionine pre-treatment on alcohol-induced exencephaly and axial skeletal dysmorphogenesis in mouse fetuses.

Alcohol is known to induce folate deficiency and impair methionine synthase activity. Exogenous folic acid (FA) administered periconceptionally has been shown to prevent the first occurrence and recurrence of neural tube defects (NTD) in humans. Since folate, vitamin B(12) and methionine are metabolically interrelated, it was decided to determine the effect of methionine pre-treatment on alcohol-induced NTD and axial skeletal defects in mouse embryos. Following administration of a single dose of 70 or 150 mg/kg of methionine, 0.03 ml/g body weight of ethanol solution (25% v/v of absolute alcohol in saline) was injected intraperitoneally into pregnant mice at critical stages of neural tube development. The controls were either non-treated or saline treated and pair-fed and pair-watered. Fetuses were collected on gestation day 18. Alcohol and methionine plus alcohol numerically enhanced embryonic resorption and induced a significant reduction in fetal body weight. Alcohol alone caused a 3-fold increase in the background frequency of exencephaly in gestation days 7 and 8 treatment groups. The low dose of methionine only numerically reduced the spontaneous exencephaly. Pre-treatment with methionine only produced a numerical but not statistically significant reduction in alcohol-induced exencephaly. The higher dose of methionine did not produce a particularly beneficial effect on embryonic survival, fetal body weight and occurrence of exencephaly. Alcohol-induced cleft palate and limb malformations were ameliorated by methionine pre-treatment. Craniofacial skeleton, vertebrae and ribs were extensively malformed both in the alcohol and methionine plus alcohol groups indicating a lack of rescue effects of methionine. Whereas supernumerary ribs and extra sternal ribs were augmented by methionine, occipitalization of the atlas vertebra was a malformation unique to the pre-treatment group. Plasma levels of several amino acids including that of methionine were significantly lowered by alcohol. Pre-treatment with methionine produced a dose dependent enhancement of only methionine concentration. These data suggest that pre-administration of methionine only rescues mouse embryos of certain non-neural malformations and that the lack of ameliorative effect on NTD and axial skeletal defects may be due to the fact that alcohol lowers the concentration of a number of amino acids and therefore, supplementation should comprise a mixture of these amino acids and possibly FA and vitamin B(12).

An improved gravitational search algorithm for optimal placement and sizing of renewable distributed generation units in a distribution system for power quality enhancement

Distributed generation (DG) is an important element to be considered in distribution planning since it plays a major role in stability and power quality improvement. This paper presents a new method for determining optimal sizing and placement of DG in a distribution system. A multi-objective function is formed to minimize the total losses, average total voltage harmonic distortion, and voltage deviation in the distribution system. The improved gravitational search algorithm (IGSA) is proposed as an optimization techniques and its performance is compared with other optimization techniques such as particle swarm optimization (PSO) and GSA. The load flow algorithm from MATPOWER and harmonic load flow was integrated in MATLAB environment to solve the proposed multi-objective function. Finally, the proposed algorithm is tested on the radial 69-bus distribution system with three case studies. The results show that the IGSA performs better than PSO and GSA by giving the best fitness value and the fastest average elapsed time.

A single monitor method for voltage sag source location using Hilbert Huang transform

This paper introduces a method for voltage sag source location based on Hilbert Huang transformed monitored current signal. Unlike the traditional method, the proposed method first transforms the recorded current during the sag event to obtain frequency-time plot (Hilbert spectra) and IMF plot before the location of voltage sag source is determined. Then based on the change in frequency and IMF the relative location of voltage sag source is obtained. The effectiveness of the proposed method has been verified through simulation on 20 bus system and by comparing with an existing S-Transform based method. The results show that the presented method can determine the location of voltage sag source correctly.

Optimal Battery Sizing in Photovoltaic Based Distributed Generation Using Enhanced Opposition-Based Firefly Algorithm for Voltage Rise Mitigation

This paper presents the application of enhanced opposition-based firefly algorithm in obtaining the optimal battery energy storage systems (BESS) sizing in photovoltaic generation integrated radial distribution network in order to mitigate the voltage rise problem. Initially, the performance of the original firefly algorithm is enhanced by utilizing the opposition-based learning and introducing inertia weight. After evaluating the performance of the enhanced opposition-based firefly algorithm (EOFA) with fifteen benchmark functions, it is then adopted to determine the optimal size for BESS. Two optimization processes are conducted where the first optimization aims to obtain the optimal battery output power on hourly basis and the second optimization aims to obtain the optimal BESS capacity by considering the state of charge constraint of BESS. The effectiveness of the proposed method is validated by applying the algorithm to the 69-bus distribution system and by comparing the performance of EOFA with conventional firefly algorithm and gravitational search algorithm. Results show that EOFA has the best performance comparatively in terms of mitigating the voltage rise problem.

Power quality monitor placement method using adaptive quantum-inspired binary gravitational search algorithm

This paper presents application of adaptive quantum-inspired binary gravitational search algorithm for solving optimal power quality monitor (PQM) placement for voltage sag assessment. The optimization involves multi objectives and handles observability constraint determined by the concept of topological monitor reach area. The overall objective function consists of two functions which are monitor overlapping index and sag severity index. In this algorithm, the quantum-inspired binary gravitational search algorithm is improved by applying the concept of artificial immune system as to make it adaptive towards the changes of constraints. The proposed algorithm is applied on the 69-bus distribution system and compared to the conventional method so as to illustrate its effectiveness.

A Nature Inspired Heuristic Optimization Algorithm Based on Lightning

This paper presents a nature inspired heuristic optimization algorithm based on lightning process called the lightning search algorithm (LSA) to solve optimization problems. It is derived from the natural phenomenon of lightning and the process of step leader propagation using the theory of fast particles. Three particle types are established to characterize the transition particles that generate the first step leader population, the space particles that try to become the leader, and the lead particle that represent the particle excited from best positioned step leader. To access the correctness and efficiency of the suggested algorithm, the LSA is verified using a well-used 10 benchmark functions with several characteristics. A comparative study with two other established methods is conducted to confirm and compare the performance of the LSA. The result exhibits that the LSA usually delivers better results compared with the other experimented methods with a high convergence rate.