ArticlePublisher preview available

Hybridizing grey wolf optimization with neural network algorithm for global numerical optimization problems

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

This paper proposes a novel hybrid algorithm, called grey wolf optimization with neural network algorithm (GNNA), for solving global numerical optimization problems. The core idea of GNNA is to make full use of good global search ability of neural network algorithm (NNA) and fast convergence of grey wolf optimizer (GWO). Moreover, both NNA and GWO are improved to boost their own advantages. For NNA, an improved NNA is given to strengthen the exploration ability of NNA by discarding transfer operator and introducing random modification factor. For GWO, an enhanced GWO is presented, which adjusts the exploration rate based on reinforcement learning principles. Then the improved NNA and the enhanced GWO are hybridized by dynamic population mechanism. A comprehensive set of 23 well-known unconstrained benchmark functions are employed to examine the performance of GNNA compared with 13 metaheuristic algorithms. Such comparisons suggest that the combination of the improved NNA and the enhanced GWO is very effective and GNNA is clearly seen to be more successful in both solution quality and computational efficiency.
This content is subject to copyright. Terms and conditions apply.
ORIGINAL ARTICLE
Hybridizing grey wolf optimization with neural network algorithm
for global numerical optimization problems
Yiying Zhang
1
Zhigang Jin
1
Ye Chen
1,2
Received: 19 January 2019 / Accepted: 19 October 2019 / Published online: 28 October 2019
ÓSpringer-Verlag London Ltd., part of Springer Nature 2019
Abstract
This paper proposes a novel hybrid algorithm, called grey wolf optimization with neural network algorithm (GNNA), for
solving global numerical optimization problems. The core idea of GNNA is to make full use of good global search ability
of neural network algorithm (NNA) and fast convergence of grey wolf optimizer (GWO). Moreover, both NNA and GWO
are improved to boost their own advantages. For NNA, an improved NNA is given to strengthen the exploration ability of
NNA by discarding transfer operator and introducing random modification factor. For GWO, an enhanced GWO is
presented, which adjusts the exploration rate based on reinforcement learning principles. Then the improved NNA and the
enhanced GWO are hybridized by dynamic population mechanism. A comprehensive set of 23 well-known unconstrained
benchmark functions are employed to examine the performance of GNNA compared with 13 metaheuristic algorithms.
Such comparisons suggest that the combination of the improved NNA and the enhanced GWO is very effective and GNNA
is clearly seen to be more successful in both solution quality and computational efficiency.
Keywords Artificial neural networks Reinforcement learning Grey wolf optimizer Numerical optimization
1 Introduction
In the real world, optimization problems can be found in
almost all engineering fields. Solving optimization problem
is to find an optimal solution from all possible solutions of
the given constrained space to maximize or minimize its
objective function. Optimization approaches can be
broadly divided into two types: deterministic methods and
metaheuristic methods. As conventional optimization
approaches, deterministic methods apply specific
mathematical principles at each iteration and may need
other information like gradient, initial points and hessian
matrix [1,2]. Although deterministic methods can be
viewed as available options for some simple and ideal
optimization problems, they are not effective in solving
complex optimization problems such as large-scale, mul-
timodal and highly constrained engineering optimization
problems [3,4]. Metaheuristic algorithms are modern
optimization methods, which commonly operate by some
defined principles and randomness to imitate natural phe-
nomena and are proving to be better than conventional
optimization methods in solving complex practical opti-
mization problems.
A lot of metaheuristic algorithms have been developed
over the last two decades. These algorithms can be roughly
separated into the following four categories according to
different types of inspiration:
1. Swarm intelligence algorithms. These algorithms are
inspired from some behaviour of animal and plant,
such as foraging process of bird flocking in particle
swarm optimization (PSO) [5], obligate brood parasitic
behaviour of some cuckoo species in cuckoo search
(CS) [6], echolocation behaviour of bats in bat
&Zhigang Jin
zgjin@tju.edu.cn
Yiying Zhang
zhangyiying@tju.edu.cn
Ye Chen
chenye1132@163.com
1
School of Electrical and Information Engineering, Tianjin
University, 92 Weijin Road, Tianjin 300072,
People’s Republic of China
2
College of Applied Science and Technology, Hainan
University, 58 People Avenue, Haikou 570228, People’s
Republic of China
123
Neural Computing and Applications (2020) 32:10451–10470
https://doi.org/10.1007/s00521-019-04580-4(0123456789().,-volV)(0123456789().,-volV)
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Neural Network Algorithm(NNA) [1] is a recently proposed meta-heuristic for single objective optimization problems. The NNA has proved its ability in solving various types of single objective optimization problems [25][26][27][28][29][30][31][32] . In this paper, the NNA has been restructured based on new search mechanisms and converted into a multi-objective optimizer to find the optimal solutions for MOPs. ...
... In the literature, the NNA has demonstrated its capacity to address single-objective optimization problems.Some of the applications are: 3D printed acrylonitrile butadiene styrene polymer [25] , PEM fuel cells [26,27] , engineering optimization problems [27][28][29] , robot manipulator arms [30] , shale reservoir [31] , and natural gas liquefaction plant [32] . However, so far its multiobjective version and its applications for solving the MOPs have not been investigated. ...
Article
Full-text available
Neural Network Algorithm (NNA) is a recently proposed Metaheuristic that is inspired by the idea of artificial neural networks. The performance of NNA on single-objective optimization problems is very promising and effective. In this article, a maiden attempt is made to restructure NNA for its possible use to address multi-objective optimization problems. To make NNA suitable for MOPs several fundamental changes in the original NNA are proposed. A novel concept is proposed to initialize the candidate solution, position update, and selection of target solution. To examine the optimization ability of the proposed scheme, it is tested on several benchmark problems and the results are compared with eight state-of-the-art multi-objective optimization algorithms. Inverse generational distance(IGD) and hypervolume (HV) metrics are also calculated to understand the optimization ability of the proposed scheme. The results are statistically validated using Wilcoxon signed rank test. It is observed that the overall optimization ability of the proposed scheme to solve MOPs is very good. • This paper proposes a method to solve multi-objective optimization problems. • A multi-objective Neural Network Algorithm method is proposed. • The proposed method solves difficult multi-objective optimization problems.
... To address these limitations, researchers have endeavored to enhance the NNA algorithm's performance by integrating various search operators into its framework. For instance, in [13], a hybrid algorithm termed GNNA is proposed, amalgamating the fast convergence capabilities of the Grey Wolf Optimizer (GWO) with the high exploration potential of the NNA algorithm. Similarly, in [14], the TLNNA hybrid approach combines elements of the Teaching-Learning-Based Optimization (TLBO) and NNA algorithms to tackle engineering optimization problems. ...
Preprint
Full-text available
In recent years, the optimization of virtual machine placement (VMP) in cloud data centers has emerged as a crucial and complex challenge, garnering considerable attention from researchers. Due to its NP-Hard nature, metaheuristic algorithms have become a popular approach in addressing this problem. These algorithms typically initiate with the random generation of initial solutions, which are then iteratively refined using specific operators to find the optimal solution. Among these algorithms, the Neural Network Algorithm (NNA) stands out as a promising swarm optimization technique known for its strong global search capability, making it well-suited for tackling various intricate optimization tasks. However, NNA often suffers from slow convergence due to its limited exploitation capability, thereby hindering its practical utility in optimization problem-solving. To address this limitation, this study proposes an approach to enhance the convergence speed of NNA while achieving a better balance between exploitation and exploration. Specifically, we adopt a heuristic algorithm to generate initial solutions in a more suitable and less random manner for the VMP problem. Additionally, the search operators of the algorithm are optimized using Cauchy and Lévy distributions. We evaluate the performance of the Improved Biogeography-based Neural Network Algorithm (IBNNA) on synthetic datasets of varying dimensions and compare the results with existing similar algorithms in the literature. The experimental findings demonstrate that the proposed algorithm outperforms other methods in terms of physical machine utilization, convergence rate, and power consumption across most experimental scenarios.
... Development of biological inspired meta heuristic strategy of GWO developed by Mirjalili (Mirjalili et al., 2014;Faris et al., 2018) is fascinating methodology to be applied to stiff scenarios of practical ELD problem. Numerous preponderant problems of optimization are addressed using GWO (Alzubi et al., 2019;Salgotra et al., 2019;Zhang et al., 2020b) that includes feature selection (Chantar et al., 2020), vehicular adhoc networks (Fahad et al., 2018), power system stabilizer design (Shakarami and Davoudkhani, 2016), hydro-power prediction (Dehghani et al., 2019) and energy management (Jiang, 2021;Yang et al., 2022). ...
Article
Full-text available
This research presents a novel methodology for tackling the combined thermal-wind economic load dispatch (ELD) issue in contemporary power system. The proposed approach involves hybridizing active-set algorithm (ASA), interior point algorithm (IPA) and sequential quadratic programming (SQP) into grey wolf optimization (GWO) algorithm, while effectively incorporating the intricacies associated with renewable energy sources (RES). A more accurate model is made possible by hybridization for complex systems with memory and hereditary characteristics. The GWO is used as a tool for global search while ASA, IPA and SQP methods are used for rapid local optimization mechanism. The performance evaluation of the design heuristics is carried out on 37 thermal and 3 wind power generating units and outcomes endorse the effectiveness of the proposed scheme over state-of-the-art counterparts. The worthy performance is further validated on statistical assessments in case of thermal-wind integrated ELD problem in terms of measure of central tendency and variation on cost and complexity indices.
... They study the performance of the proposed GNNA algorithm using a comprehensive set of 23 well-known unconstrained benchmark functions. [32]. ...
Article
Full-text available
Recognizing sign language is one of the most challenging tasks of our time. Researchers in this field have focused on different types of signaling applications to get to know typically, the goal of sign language recognition is to classify sign language recognition into specific classes of expression labels. This paper surveys sign language recognition classification based on machine learning (ML), deep learning (DL), and optimization algorithms. A technique called sign language recognition uses a computer as an assistant with specific algorithms to evaluate basic sign language recognition. The letters of the alphabet were represented through sign language, relying on hand movement to communicate between deaf people and normal people. This paper presents a literature survey of the most important techniques used in sign language recognition models
... An artificial neural network (ANN) is a computer system whose architecture and operation are inspired by the knowledge of biological neurons in the human brain [3] [10] [11]. Another definition of an artificial neural network by Faucett (1994) is an information processing system with properties like biological neural networks [12]. ...
Article
Full-text available
Electrical Energy must be provided in an amount according to needs. Energy that exceeds consumption needs causes power loss. On the other hand, when electricity is scarce, it causes blackouts. To produce electrical energy that meets these needs, there must be a plan for the provision of electrical energy which is carried out by forecasting electricity consumption. Therefore, forecasting electricity consumption is very important to ensure electricity efficiency. This research was conducted in the province of South Sulawesi, Indonesia. The research method used is the Artificial Neural Network (ANN) method. The results of forecasting energy consumption show that the Artificial Neural Network method, Network Type back-propagation, and the TRAINGDX training function of 1480.133602 MW are closest to the target value of 1480.167515 MW or a difference of 0.033913 MW, Mean Square Error (MSE) value is 0.000002131. TRAINCGB is 1480.115899 MW or a difference of 0.051616 MW, the Mean Square Error (MSE) value is 0.000003226. This forecast shows that the results are accurate. Streszczenie. Energia elektryczna musi być zapewniona w ilości dostosowanej do potrzeb. Energia przekraczająca zapotrzebowanie powoduje utratę mocy. Z drugiej strony, gdy brakuje prądu, powoduje to przerwy w dostawie prądu. Aby wyprodukować energię elektryczną zaspokajającą te potrzeby, musi istnieć plan dostarczania energii elektrycznej, który odbywa się poprzez prognozowanie zużycia energii elektrycznej. Dlatego prognozowanie zużycia energii elektrycznej jest bardzo ważne dla zapewnienia efektywności energetycznej. Badania przeprowadzono w prowincji Sulawesi Południowe w Indonezji. Zastosowaną metodą badawczą jest metoda sztucznej sieci neuronowej (ANN). Wyniki prognozowania zużycia energii pokazują, że metoda sztucznej sieci neuronowej, propagacja wsteczna typu sieci oraz funkcja ucząca TRAINGDX wynosząca 1480,133602 MW są najbliższe docelowej wartości 1480,167515 MW lub różnicy 0,033913 MW, średniego błędu kwadratowego (MSE). wartość wynosi 0,000002131. TRAINCGB wynosi 1480,115899 MW lub różnica 0,051616 MW, wartość błędu średniokwadratowego (MSE) wynosi 0,000003226. Prognoza ta pokazuje, że wyniki są trafne. (Prognozowanie zużycia energii elektrycznej w Południowym Sulawesi przy użyciu sztucznej sieci neuronowej)
... These two mechanisms dictate the generation of new candidate solutions based on the previous ones, enabling the algorithms to have global exploration and efficient search [34,46]. Various metaheuristics have been developed over the past decade and are broadly classified into four groups [75]: ...
Article
Full-text available
Given the importance and interest of buildings in the urban environment, numerous studies have focused on automatically extracting building outlines by exploiting different datasets and techniques. Recent advancements in unmanned aerial vehicles (UAVs) and their associated sensors have made it possible to obtain high-resolution data to update building information. These detailed, up-to-date geographic data on the built environment are essential and present a practical approach to comprehending how assets and people are exposed to hazards. This paper presents an effective method for extracting building outlines from UAV-derived orthomosaics using a semantic segmentation approach based on a U-Net architecture with a ResNet-34 backbone (UResNet-34). The novelty of this work lies in integrating a grey wolf optimiser (GWO) to fine-tune the hyperparameters of the UResNet-34 model, significantly enhancing building extraction accuracy across various localities. The experimental results, based on testing data from four different localities, demonstrate the robustness and generalisability of the approach. In this study, Locality-1 is well-laid buildings with roads, Locality-2 is dominated by slum buildings in proximity, Locality-3 has few buildings with background vegetation and Locality-4 is a conglomeration of Locality-1 and Locality-2. The proposed GWO-UResNet-34 model produced superior performance, surpassing the U-Net and UResNet-34. Thus, for Locality-1, the GWO-UResNet-34 achieved 94.74% accuracy, 98.11% precision, 84.85% recall, 91.00% F1-score, and 88.16% MIoU. For Locality-2, 90.88% accuracy, 73.23% precision, 75.65% recall, 74.42% F1-score, and 74.06% MioU was obtained.The GWO-UResNet-34 had 99.37% accuracy, 90.97% precision, 88.42% recall, 89.68% F1-score, and 90.21% MIoU for Locality-3, and 95.30% accuracy, 93.03% precision, 89.75% recall, 91.36% F1-score, and 88.92% MIoU for Locality-4.
... Son zamanlarda en uygun çözümlere ulaşmak için geliştirilen yeni birkaç meta-sezgisel yöntem önerilmiştir [24][25][26][27][28][29][30][31][32][33][34][35]. Eldeki soruna bağlı olarak, tüm algoritmalar bazı iyileştirmeler gerektirmektedir. ...
Article
Sayısal iyileştirme, mühendislik alanında en çok uğraşılan problemlerden biridir. Bu çalışmada, son zamanlarda geliştirilen Çift-Girişim Tabanlı İyileştirme Algoritması’nın (Bi-Attempted Based Optimization Algorithm) (ABaOA) arama yakınsama kabiliyeti yirmi iyi bilinen referans fonksiyonu üzerinde test edilmiştir. Elde edilen sonuçlar Genetik Algoritma (GA) ve Temel İyileştirme Algoritması (Based Optimization Algoritması) (BaOA) ile karşılaştırılmıştır. ABaOA, tüm yinelemeler boyunca iki sabit adım boyutlu çoğaltma parametresi ve iki işlem operatörü kullanan nüfus tabanlı bir Evrimsel Algoritma’dır. Evrimsel algoritmalar arama alanı boyunca global optimuma hızlı bir şekilde yaklaşır ve uygulanabilir bir çözümü garanti ederler. Deneysel sonuçlar ABaOA'nın hem BAOA'ya hem de GA'ya göre global optimuma daha hızlı yaklaştığını açıkça göstermiştir.
Article
Full-text available
Global optimization problems have been a research topic of great interest in various engineering applications among which neural network algorithm (NNA) is one of the most widely used methods. However, it is inevitable for neural network algorithms to plunge into poor local optima and convergence when tackling complex optimization problems. To overcome these problems, an improved neural network algorithm with quasi-oppositional-based and chaotic sine-cosine learning strategies is proposed, that speeds up convergence and avoids trapping in a local optimum. Firstly, quasi-oppositional-based learning facilitated the exploration and exploitation of the search space by the improved algorithm. Meanwhile, a new logistic chaotic sine-cosine learning strategy by integrating the logistic chaotic mapping and sine-cosine strategy enhances the ability that jumps out of the local optimum. Moreover, a dynamic tuning factor of piecewise linear chaotic mapping is utilized for the adjustment of the exploration space to improve the convergence performance. Finally, the validity and applicability of the proposed improved algorithm are evaluated by the challenging CEC 2017 function and three engineering optimization problems. The experimental comparative results of average, standard deviation, and Wilcoxon rank-sum tests reveal that the presented algorithm has excellent global optimality and convergence speed for most functions and engineering problems.
Article
Full-text available
The Dragonfly Algorithm (DA) is a recently proposed heuristic search algorithm that was shown to have excellent performance for numerous optimization problems. In this paper, a wrapper-feature selection algorithm is proposed based on the Binary Dragonfly Algorithm (BDA). The key component of the BDA is the transfer function that maps a continuous search space to a discrete search space. In this study, eight transfer functions, categorized into two families (S-shaped and V-shaped functions) are integrated into the BDA and evaluated using eighteen benchmark datasets obtained from the UCI data repository. The main contribution of this paper is the proposal of time-varying S-shaped and V-shaped transfer functions to leverage the impact of the step vector on balancing exploration and exploitation. During the early stages of the optimization process, the probability of changing the position of an element is high, which facilitates the exploration of new solutions starting from the initial population. On the other hand, the probability of changing the position of an element becomes lower towards the end of the optimization process. This behavior is obtained by considering the current iteration number as a parameter of transfer functions. The performance of the proposed approaches is compared with that of other state-of-art approaches including the DA, binary grey wolf optimizer (bGWO), binary gravitational search algorithm (BGSA), binary bat algorithm (BBA), particle swarm optimization (PSO), and genetic algorithm in terms of classification accuracy, sensitivity, specificity, area under the curve, and number of selected attributes. Results show that the time-varying S-shaped BDA approach outperforms compared approaches.
Article
Full-text available
In this research, a new metaheuristic optimization algorithm, inspired by biological nervous systems and artificial neural networks (ANNs) is proposed for solving complex optimization problems. The proposed method, named as neural network algorithm (NNA), is developed based on the unique structure of ANNs. The NNA benefits from complicated structure of the ANNs and its operators in order to generate new candidate solutions. In terms of convergence proof, the relationship between improvised exploitation and each parameter under asymmetric interval is derived and an iterative convergence of NNA is proved theoretically. In this paper, the NNA with its interconnected computing unit is examined for 21 well-known unconstrained benchmarks with dimensions 50–200 for evaluating its performance compared with the state-of-the-art algorithms and recent optimization methods. Besides, several constrained engineering design problems have been investigated to validate the efficiency of NNA for searching in feasible region in constrained optimization problems. Being an algorithm without any effort for fine tuning initial parameters and statistically superior can distinguish the NNA over other reported optimizers. It can be concluded that, the ANNs and its particular structure can be successfully utilized and modeled as metaheuristic optimization method for handling optimization problems.
Article
Grey wolf optimizer (GWO) algorithm is a relatively novel population-based optimization technique that has the advantage of less control parameters, strong global optimization ability and easy of implementation. It has received significant interest from researchers in different fields. However, there is still an insufficiency in the GWO algorithm regarding its position-updated equation, which is good at exploitation but poor at exploration. In this work, we proposed an improved algorithm called the exploration-enhanced GWO (EEGWO) algorithm. In order to improve the exploration, a new position-updated equation is presented by applying a random individual in the population to guide the search of new candidate individuals. In addition, in order to make full use of and balance the exploration and exploitation of the GWO algorithm, we introduced a nonlinear control parameter strategy, i.e., the control parameter of → í µí±Ž is nonlinearly increased over the course of iterations. The experimental result on a set of 23 benchmark functions and 4 engineering applications demonstrate the effectiveness and efficiency of the modified position-updated equation and the nonlinear control parameter strategy. The comparisons show that the proposed EEGWO algorithm significantly improves the performance of GWO. Moreover, EEGWO offers the highest solution quality, strongest robustness, and fastest global convergence among all of the contenders on almost all of the test functions.
Article
This paper presents an on-line variable-fidelity surrogate-assisted harmony search algorithm (VFS-HS) for expensive engineering design optimization problems. VFS-HS employs a novel model-management strategy that uses a multi-level screening mechanism based on non-dominated sorting to strictly control the numbers of low-fidelity and high-fidelity evaluations and to keep a balance between exploration and exploitation. The performance of VFS-HS is validated through comparison not only to those of four single-fidelity surrogate-assisted optimization methods (i.e. the particle swarm optimization algorithm with radial basis function-based surrogate (OPUS-RBF), the two-layer surrogate-assisted particle swarm optimization algorithm (TLSAPSO), the surrogate-assisted hierarchical particle swarm optimization (SHPSO) and the hybrid surrogate-based optimization using space reduction (HSOSR)) but also to that a multi-fidelity surrogate-assisted optimization method (the multi-fidelity Gaussian process and radial basis function-model-assisted memetic differetial evolution (MGPMDE)) on the CEC2014 expensive optimization test suite. A real-world problem of the optimal design for a long cylindrical gas-pressure vessel is also investigated. The results show that VFS-HS outperforms all the compared methods.
Article
Parameter extraction of solar photovoltaic (PV) models is a typical complex nonlinear multivariable strongly coupled optimization problem. The original differential evolution (DE) is good at exploring the search space and locating the region of global optimum, but it is slow at exploitation of the solutions. Quite the opposite, the original whale optimization algorithm (WOA) is good at exploiting the population information, but it easily suffers from premature convergence. In such a context, in this paper, an effective hybrid method named DE/WOA by combining the exploration of DE with the exploitation of WOA is proposed for extracting the accurate parameters of PV models. A set of 13 numerical benchmark functions with different characteristics is firstly employed to verify the performance of DE/WOA. Then, DE/WOA is applied to parameter extraction of three PV models, i.e., single diode, double diode, and PV module models. Finally, DE/WOA is implemented to a practical PV power station in the Guizhou Power Grid of China to further validate its effectiveness under different irradiances, temperatures, and dynamic weather conditions. All the experimental results comprehensively demonstrate that DE/WOA performs significantly better than the original DE, WOA, and five advanced variants of them and is highly competitive with some recently-proposed parameter extraction methods.
Article
In this paper, a new hybrid GSA-GA algorithm is presented for the constraint nonlinear optimization problems with mixed variables. In it, firstly the solution of the algorithm is tuned up with the gravitational search algorithm and then each solution is upgraded with the genetic operators such as selection, crossover, mutation. The performance of the algorithm is tested on the several benchmark design problems with different nature of the objectives, constraints and the decision variables. The obtained results from the proposed approach are compared with the several existing approaches result and found to be very profitable. Finally, obtained results are verified with some statistical testing.
Article
This paper presents a novel metaheuristic algorithm called queuing search (QS), which is inspired from human activities in queuing. Some common phenomena are considered in QS: 1) customers actively follow the queue that provides fast service; 2) each customer service is mainly affected by the staff or customer itself; and 3) a customer can be influenced by others during the service when the queue order is not strictly maintained. The performance of QS is tested on 30 bound-constrained benchmark functions scalable with 30 and 100 dimensions from CEC 2014, 5 standard and 4 challenging constrained engineering optimization problems. Meanwhile, comparisons are performed among the results of QS and some state-of-the-art or well-known metaheuristic algorithms.
Article
The grey wolf optimizer (GWO) is a new meta-heuristic algorithm inspired from the leadership and prey searching, encircling, and hunting of the grey wolves’ community. The GWO algorithm has the advantages of simplicity (less control parameters), flexibility, and globalism. In this paper, a simple and efficient augmentation for the GWO (AGWO) algorithm is proposed for better hunting performance. The AGWO algorithm focuses on increasing the possibility of the exploration process over the exploitation process by modifying the behavior of the control parameter (a) and position updating. The AGWO is suitable to the low number of search agents such as the electric power system application. The proposed AGWO algorithm is verified using twenty-three benchmark test functions and is applied to the grid-connected permanent magnet synchronous generator driven by variable speed wind turbine (PMSG-VSWT). The obtained results of the AGWO algorithm are compared with the results of the original GWO and other algorithms. The comparisons verified that the proposed AGWO is significantly augmented the performance of the original GWO algorithm without affecting its simplicity and easy implementation.