Abstract
Jaya, a simple heuristic algorithm, has shown attractive features, especially parameter-free. However, the simple structure of Jaya algorithm may result in poor performances, to boost the performance, a multi-strategy Jaya (MJaya) algorithm based on multi-population has been proposed in this paper. Three strategies correspond to three groups of solutions. The first strategy based on the first population is to introduce an adaptive weight parameter to the position-updating equation to improve the local search. The second strategy is based on rank-based mutation to enhance the global search. The third strategy is to exploit around the best solution to reinforce the local search. Three strategies cooperate well during the evolution process. The experimental results based on CEC 2014 have proven that the proposed MJaya is superior compared with Jaya and its latest variants. Then, the proposed MJaya algorithm is used to solve three industrial problems and the results have shown that the proposed MJaya algorithm can also solve complex industrial applications effectively.
Introduction
In the past several years, various meta-heuristic algorithms have been developed. Nowadays, most of them have been successfully used in industrial applications. Compared with the conventional mathematical methods, these algorithms do not demand to calculate the gradient information. They are simple, flexible, and derivation-free, which make them attractive when solving these optimization problems.
It is necessary to determine the algorithm-specific parameter values when using these meta-heuristic algorithms. For example, Particle Swarm Optimization (PSO) utilizes inertia weight, cognitive and social parameters, Genetic algorithm (GA) uses mutation and crossover probabilities, Differential Evolution (DE) employs scale factor and crossover rate, and so on. Parameter tuning is a very tedious and time-consuming task. Compared with these algorithms, Jaya is a novel algorithm, which doesn’t have any algorithm-specific parameters. Jaya is a novel algorithm, proposed by Rao in 2016 [1]. The algorithm optimizes problems by approaching the best solution and keeping away from the worst solution. As the algorithm is parameter-free and has a very simple structure, it has been utilized to solve plenty of industrial problems, such as photovoltaic models [2], job shop scheduling problems [3], text document clustering [4], traveling salesman problem [5], reservoir operation [6], and so on.
Like most meta-heuristic algorithms, Jaya may suffer from premature and be trapped into the local optimum [7]. The industrial optimization problems are often complex and hence more improvement algorithms based on Jaya have been put forward [8]. The first improvement is based on the chaotic technique, which is used as a random mechanism to improve the exploration of Jaya. Farah and Belazi [9] integrated the technique into Jaya algorithm to develop chaotic Jaya, with the aim of alleviating the drawbacks of Jaya. Yu et al., [10] developed a multi-population based on the chaotic approach and Jaya to guarantee the optimal solution of the problem. Jiana and Weng [11] developed a logistic chaotic Jaya algorithm on the basis of the logistic chaotic map method, which can boost the diversity of the population. Lévy flight was used [12] as a chaotic method to push the Jaya algorithm to have a large jump, which can start a new search in the different search regions and avoid local optimum. Migallón et al., [13] pointed out that it was necessary to speed up the convergence of Jaya and then, a chaotic method was used. To balance the global and local search capabilities of the Jaya algorithm, Leghari [14] introduced a dynamic weight parameter to update the expression of the entire solutions.
The second improvement is the adaptive approach. The method can automatically tune the parameters of meta-heuristic algorithms. In the Jaya algorithm, the approach is mainly used to tune the population size. Rao and More [15] developed a self-adaptive Jaya algorithm to dynamically adjust the population size and use the adaptive Jaya to optimize the mechanical draft cooling tower system. A similar technique is used in the Enhanced Jaya algorithm(EJaya) [16] which was applied to estimate the parameters of photovoltaic solar cells and modules. In another version of EJaya, the local exploitation is according to the defined lower and upper local attractors while global exploration is based on the historical population [17]. Premkumar et al., [18] used an adaptive weight to adjust the tendency of the current population to be close to the best solution and avoid the worst solution, logistic, tent map, and sine chaotic methods to optimize the best solution. Pervez et al., [19] realized an adaptive Jaya, in which two adaptive parameters were used to solve the power point tracking of the photovoltaic system. Surrogate-assisted Jaya based on historical learning mechanism and optimal directional guidance is developed to solve optimization problems [20]. Comprehensive learning Jaya is designed for solving engineering problems, in which the information population is fully used [21].
The third improvement is the elite-based Jaya algorithm. It uses the survival of the fittest to select the powerful solution toward optimality. Raut and Mishra [22] proposed an elitist–Jaya algorithm, in which elitism strategy was used to adjust solutions on the basis of the neighborhood search and an adaptive linear inertia weight was used to balance local and global search. Rao and Saroj [23] implemented an elite-based Jaya algorithm with a single evolution phase and simple structure. In another work, Rao and Saroj [24] developed an elitist-based multi-objective Jaya algorithm to optimize the effectiveness and total cost of the heat exchangers.
These improvements have boosted the performance of the conventional Jaya algorithm. It is also noticed that most of these improvements are based on a single updating strategy, which keeps away from the worst solution and approaches the best solution. Multi-strategies and multi-population are rarely involved in these improvements. On the one hand, the single updating strategy of Jaya algorithm may result in poor diversity of the population, poor exploration, and exploitation. The algorithm may be trapped into the local optimum although the convergence may be fast. The search capability of the single strategy is limited. On the other hand, plenty of research in the community of meta-heuristic algorithms has indicated that multi-population based on multi-strategy is a useful approach, which can restrain disadvantages of a single strategy and utilize advantages of each strategy [25–27]. What’s more, different optimization problems demand different evolution strategies. Different strategies may be better during evolution than a single strategy [28]. Based on these observations, a Multi-strategy Jaya (MJaya) algorithm is developed in this paper. In the proposed MJaya algorithm, three updating strategies are involved. The first one is to extend the conventional updating strategy of Jaya algorithm by introducing an adaptive weight parameter to enhance the exploration at the early stage and boost the exploitation at the later stage. The second strategy is to enhance the global search capacity by introducing the ranking-based mutation strategy. The third strategy is to mend the best solution, which is the most important solution to guide the search direction. A chaotic method is adopted to update the best solution to boost the exploitation. Through these three updating strategies, the local and global search capacity of MJaya is greatly boosted. We use the proposed MJaya algorithm to solve the CEC 2014 and these three typical industrial problems related to frequency-modulated sound waves, environmental economic dispatch, and parameters identification of photovoltaic models. These experimental results demonstrate that the proposed MJaya algorithm is superior and can solve complex industrial problems.
Therefore, the main the novelty of the paper can be summarized as follows: An adaptive weight parameter is introduced into Jaya to adjust the global and local search. A rank-based mutation mechanism is integrated into Jaya to boost the exploration. Multi-strategy Jaya (MJaya) algorithm based on multi-population has been proposed. Three industrial applications have demonstrated the effectiveness of MJaya.
The paper is organized as follows: In Section 2, the Jaya algorithm is briefly presented. In Section 3, the proposed MJaya algorithm is elaborately designed. In Section 4, the experiments are performed and the conclusions are made in Section 5.
Jaya algorithm
Jaya is one of the novel population-based optimization algorithms, which was developed by Rao in 2016 [1]. Its main feature is that it has no additional parameters, which makes it different from the conventional evolutionary algorithms. It is known that tuning parameters is a tedious task for evolutionary algorithms. During the evolution, Jaya optimizes solutions by approaching the best solution and keeping away from the worst solution.
Let f (x) be the objective function with D dimension (j = 1, 2, 3, …, D), x ij be the value of the ith solution on jth dimension (i = 1, 2, …, NP) and NP be the number of solutions, in which x i = (xi,1, xi,2, …, xi,D) is the position of the solution i. Let x best = (xbest,1, xbest,2, …, xbest,D) be the best solution found so far, it has the best objective function. For the minimization optimization problem, the f (x best ) is smaller than the remaining candidate solutions. On the contrary, let x worst = (xworst,1, xworst,2, …, xworst,D) be the worst solution, it has the worst objective function. Thereforethe is more than the remaining candidate solutions for the minimization problems. Like other populatn-based meta-heuristic algorithms, the first step is to initialize the population as follows:
Then, the population is evolved by the Jaya algorithm.h solution x i updates the position based on the following equation:
If the objective function of
The updating strategy used in Jaya is Eq. (2). It is a se strategy, which may result in poor population diversity and may be trapped into the local optimu For meta-heuristic algorithms, it is necessary to boost and balance the exploration vs exploitation, simultaneously. The exploration is to push candidate solutions search as broadly as possible while the exploitation is to use the existing knowledge. As the search direction is controlled by the best and worst solutions, the Jaya algorithm has relatively poor exploration and exploitation. Various improvements, such as introducing chaotic approaches, adaptive methods, and elite-based methods re proposed [8–21]. Most of the improvements are based on a single updating strategy, which ls the performance of the algorithm. Many research have demonstrated that multi-strategy is a useful method to boost the performance of meta-heuristic algorithms [25–27]. Based on the observations, we develop Multi-strategy Jaya (MJaya) algorithm, in which three strategies are ensembled. The first strategy is to introduce an adaptive weight parameter to update Eq.(2) with the aim of enhancing the exploitation. The second strategy is based on ranking mutation strategy, which can improve exploration while keeping the exploitation. The third strategy is to improve the best solution, which can further boost the exploitation.
The adaptive weight parameter
In population-based meta-heuristic algorithms, the desirable approach to converge to the optimal solution can be classified into two stages. The first stage is the beginning of evolution, the candidate solutions are encouraged to move through the whole search space. The second stage pushes the solutions search in the promising region. Based on the motivation, we introduce an adaptive weight parameter as follows:
This strategy is to improve the exploration. Most of the exploration can be implemented by the mutation operator. However, too much exploration has a high risk. Better solutions should be assigned more priority to better individuals to guide the search direction. The ranking-based mutation can control the search direction by assigning more hts to better solutions. It is necessary to rank solutions depending on their fitness values from the best to the worst [29]. The selection probability can be calculated as follows:
The quality of the population is very important, which can determine the performance of the algorithm. It is further necessary to boost the exploitation of Jaya algorithm by searching around the best solution. The chaotic perturbation approach is used toind the potential solution around the current optimal solution [7, 30]. The logistic map method as the chaotic sequence is proved to be useful in previous research [7]. It is also adopted into theroposed MJaya algorithm. The self-adaptive chaotic mechanism is implemented in the proposed MJaya algorithm in order to boost the exploitation. At the beginning of the algorithm, more chaotic perturbation is performed on the best solution in order to find a better solution. At the latter stageevolution,etter solutions are found. Less chaotic perturbation is used since the current best solution is very close to the optimal solution. The process can be mathematically presented as follows:
The proposed MJaya algorithm mainly consists of the above three strategies: introducing adaptive weight parameter, ranking-based mutation, and adtive chaotic perturbation. In the optimization process, multi-population is adopted. The first population is evolved by the conventional Jaya while the second population is evolved by the ranking-based mutation. Two populations will construct a new population by the greedy selection.
The pseudo code of the proposed MJaya algorithm is prested as follows:
The flowchart of the proposed MJaya algorithm is plott in Fig. 1.
The computational complexity

The flowchart of the proposed MJaya algorithm.
The computational complexity is analyzed in this sub-Section. Let the number of solutions be NP and the dimension of the problem is D. For each iteration, the calculation the mean fitness value demands O (NP); generating the first trial vector needs O (NP × D); ranking solutions requires O (NPlog (NP)) ; generating the second trial vector demands O (NP + NP × D); the chaotic perturbation requires O (D). The total complexity of each iteration is O (NP + NP × D + NPlog (NP) + D). As the log (NP) is often smaller than D, the total complexity is O (NP × D), which is the same as that of the traditional Jaya algorithm.
The experimental results on the CEC 2014 testing suite
The first experiment is performed on CEC 2014 testinguite. In the test suite, there are 30 testing functions, which can be used to test the exploitation and exploration ability of the algorithm. The testing functions consist of unimodal, simple multi-modal, hybrid, and composition functions. Four new meta-heuristic algorithms, including Jaya and its two variants, Grey Wolf Optimizer (GWO) are used. The GWO algorithm, proposed by Mirjalili et al [31], is on the basis of the hierarchy and social status of the grey wolf. It also uses fewer parameters and a simple structure, which makes it attractive. The two Jaya variants are Improved Jaya (IJaya) [2] and Performance-Guided Jaya (PGJaya) [7]. The experience-based learning technique is adopted in IJaya while the performance-based evolution process is used in the PGJaya algorithm. Both algorithms are used previous information to guide the search direction. This is the feedback mechanism, which is often used in evolutionary algorithms.
Each algorithm runs 50 times independently to avoid randomness. The population size is 50, the dimension is 30, and the maximal function evaluations are 300 000. The best results x best can be obtained. We can calculate the error Δf = f (x best ) - f (x*), in which x* is the optimal solution to the problem and x best is the best solution obtained by the algorithm. We can get Δf during each run. We compute the mean value of Δf for 50 runs. The mean results of five algorithms are listed in Table 1, in which the best results are highlighted.
The results of GWO, Jaya, IJaya, PGJaya, and MJaya algorithms
The results of GWO, Jaya, IJaya, PGJaya, and MJaya algorithms
From Table 1, it can be found that GWO has gotten the best performance on four functions, i.e., f11, f16, f22 and f24. GWO searches for the optimal solutions mainly depending on the top three wolves. The exploitation ability is good compared with its exploration. Unfortunately, the Jaya algorithm cannot achieve any better results on thirty testing functions. The position-updating mechanism of the Jaya algorithm is simple, which results in pr local and global search capacity. The performances of IJaya and PGJaya are better than Jaya. IJaya adopts the experience-based learning method, which can enhance the diversity of the poputn. However, it does not control the search direction in this process, which deteriorates the convergence. The performance is also not very good. Compared with IJaya, PGJaya is better as it has obtained superior results on eight functions, i.e., f1, f4, f5, f17, f21, f23, f25, and f30. The reason is that PGJaya adopts two strategies randomly to boost the search capacity. The proposed MJaya algorithm is the best one among these five algorithms in that it has obtained better results on eighteen functions, i.e., f2, f3, f5 - f10, f12, f13, f15, f18, f19, f20, f23, f26, f28, and f29. The proposed MJaya algorithm even finds the optimal solutions of function 2, which is significantly better than the four algorithms. What’s more, the results from the proposed MJaya algorithm on f1, f4, f11, f14, f16, f17, f21, f24, f27 and f30. rank the second compared with the remaining four algorithms. The multi-strategy based on multi-population can attribute to superior results. During the optimization process, the first strategy based on the first population introduces the adaptive weight parameter to the tendency of the worst solution, which can boost the exploitation. The second strategy based on the second population uses the ranking-based mutation technique to control the search direction so that the exploration is enhanced. By the dy selection, two populations can reconstruct a new population. During the process, the advantages of both strategies are fully made use of. At last, the self-adaptive chaotic perturbation method is performed on the best solution to further reinforce the exploitation. Therefore, the proposed MJaya algorithm can achieve better performances compared with the four algorithms.
The average ranking of five algorithms

The convergence curves of five algorithms on f1 - f12.
The convergence rate of the proposed MJaya algorithm is evaluated by the convergence curves shown in Figs. 1–3. The convergence curves are presented by t mean of log(Δf) during the 50 runs. We use the log function to make the differences among the five algorithms more significant.

The convergence curves of five algorithms on f13 - f30.
It can be seen that the proposed MJaya algorithm has the best convergence performances while Jaya is the worst one during evolution. The trend of the convergence curve fluctuates fast, which demonstrates that a multi-strategy based on multi-population is effective to update positions of solutions and balance the local and global search.
In this section, three typical industrial applications: frequency-modulated sound waves, environmental economic dispatch, and parameters identification of photovoltaic models are solved by the above five algorithms. These applications can further prove the usefulness of meta-heuristic algorithms and the effectiveness of the proposed MJaya algorithm.
The results of five algorithms on paramete determination issue
The results of five algorithms on paramete determination issue
Wave synthesis is very important in the modern music system. In this problem, six parameters y1, y2, y3, y4, y5, y6 are required to be optimized with theurpose of minimizing the square errors between the target wave Y0 (t) and the estimated wave Y (t) [32]. The square errors can be mathematically presented as follows:

The statistical results of five algorithms.
The global economy develops very quickly, which demands lots of energy. During the consumption of these energies, it is indispensable to generate some pollutants. Nowadays, the public and government are more concerned about environmental issues and pollution control. We want to achieve harmony between the environment and the development of the economy. In order to realize the goal, we have to control pollutants emission from thermal power plants while satisfying the requirement. It is the environmental economic dispatch problem. The problem is to minimize the operating and emission cost while meeting a number of constraints, such as the system load, the minimal and maximal output of each generator, and so on.
The problem can be mathematically demonstrated as follows:
Subject to: The energy balance between generated power and demand power:
The boundary constraints of each generator unit:
The range of each generated power

The convergence curve of five algorithms.

The maximum, minimum and mean results of five algorithms when fuel load is 500 MW.
The solutions obtained from five algorithms when fuel load is 500 MW
The solutions obtained from five algorithms when fuel load is 1100 MW
We set the fuel load to 500 and 1100, respectively. The stistical results of the five algorithms are plotted in Figs. 5 6. When the demand is 500 MW, thPGJaya algorithm has obtained the best results in terms of minimum and mean values while MJaya has obtained the superior performance in terms of maximum and minimum. When the dand is 1100 MW, PGJaya, GWO, and MJaya have obtained the best maximum, minimum, anmean values. The corresponding solutions obtained by five algorithms are listed in Tables 5, 6. In all, the proposed MJaya and PGJaya have ranked top two in terms of statistical results.
Nowadays, the globe has become warmer and warmer, which is one of the critical challenges to the sustainable development of the world. New energy resources have become alternatives to take the place of traditional energy, in which solar energy is a promising one as it is clean, cheap, and inexhaustible. Solar energy is transformed into electrical energy by photovoltaic systems. It is necessary to measure the efficiency of photovoltaic systems. We need some mathematical models to evaluate the behavior of the system, in which the single anudde models are commonly used [7]. The single diode model is as follows:
The search range of decision variables
The mean and std values of five algorithms for two models
The proposed MJaya algorithm, GWO, Jaya, IJaya, and PGJaya are used to optimize this problem. The data needed in the experiment are from ref [33]. The boundaries of decision variables are listed in Table 7, q = 1.60217646 × 10-19C and k = 1.3806503 × 10-23J/K. The maximal function evaluation is 50 000 and the populatiosize is 50. After running 50 times for each algorithm on the single and double diode models, theean and standard deviation of five algorithms on double and single diodes are listed in Table 8. It can be observed that GWO and Jaya have achieved the worst performance as the structure of e twgorithms is simple and the evolution strategy is sole. On the contrary, the proposed MJaya algorithm is much better and PGJaya ranks second. The proposed MJaya algorithm adopts multi-strategy and multi-population to reinforce the search capacity, which significantly enhances the results. The convergence curve of the above five algorithms is also given in Figs. 7 8,. The value of the y-axis is log (RMSE) function, which is used to different the algorithms used. It can be found that the convergence speed of the proposed MJaya algorithm is comparatively faster. The finding further indicates that the algorithm is effective.

The maximum, minimum and mean results of five algorithms when fuel load is 1100 MW.

The convergence curves of five algorithms on a single, double diode model.
For the three industrial applications, the proposed MGJaya algorithm has achieved superior results. The main reasons behind the results are the multi-strategy and multi-population. Three strategies are performed during the evolution. The first strategy introduces an adaptive weight parameter for the positing-updating equation for the first population, which can boost the exploitation. The second strategy uses rank-based mutation, which can reinforce the exploration. The third strategy adopts chaotic techniques based on the best solution, which can enhance the quantity of population. The three strategies play different roles during the evolution and cooperate well. Hence, the very good results can be achieved by the proposed MJaya algorithm.
Jaya is a very simple and promising meta-heuristic algorithm as it is parameter-free. The simple structure of the algorithm may result in poor performance when solving complex problems. In this paper, a novel algorithm, MJaya is developed to cope with the problem by using multi-strategies and multi-population. The first strategy is used to boost the exploitation by introducing an adaptive weight parameter for the original position-updating equation. The rank-based mutation is the second strategy, which can boost the exploration. The adaptive chaotic technique is the third one, which pushes the population search around the best solution and enhances the exploitation.
The proposed MJaya algorithm is tested on 30 CEC 2014 functions. Its opponents are GWO, Jaya, IJaya, and PGJaya algorithms. The experiments based on benchmark testing functions have revealed that the proposed MJaya algorithm is competitive compared with its opponents. Then, the five algorithms are used to solve three typical industrial problems. The experimental results have proven that the proposed MJaya algorithm is superior. In the next research, we will employ the proposed MJaya algorithm to solve more complex industrial problems, such as supply chain models [34].
Footnotes
Acknowledgments
The authors would like to thank professor R. Venkata Rao, who proposed Jaya algorithm, for his very constructive comments and suggestions. This research was funded by the China Natural Science Foundation (No. 71974100), Major Project of Philosophy and Social Science Research in Colleges and Universities in Jiangsu province (2019SJZDA039), and Natural Science Foundation in Jiangsu Province (No. BK20191402) and Higher school in jiangsu province college students' practice innovation training programs (XJDC202110300130).
