Sustainability Journal (MDPI)

2009 | 1,010,498,008 words

Sustainability is an international, open-access, peer-reviewed journal focused on all aspects of sustainability—environmental, social, economic, technical, and cultural. Publishing semimonthly, it welcomes research from natural and applied sciences, engineering, social sciences, and humanities, encouraging detailed experimental and methodological r...

Optimized Data-Driven Models for Prediction of Flyrock due to Blasting in...

Author(s):

Xiaohua Ding
School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Mehdi Jamei
Faculty of Engineering, Shohadaye Hoveizeh Campus of Technology, Shahid Chamran University of Ahvaz, Dashte Azadegan 78986, Iran
Mahdi Hasanipanah
Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
Rini Asnida Abdullah
Department of Geotechnics and Transportation, Faculty of Civil Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia
Binh Nguyen Le
Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam


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Year: 2023 | Doi: 10.3390/su15108424

Copyright (license): Creative Commons Attribution 4.0 International (CC BY 4.0) license.


[Full title: Optimized Data-Driven Models for Prediction of Flyrock due to Blasting in Surface Mines]

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[Summary: This page provides citation information for the study Optimized Data-Driven Models for Prediction of Flyrock due to Blasting in Surface Mines. It includes authors, publication date, and copyright details. The abstract highlights the development of hybrid models using CFNN and LSSVM with optimization algorithms (GSA, WOA, ABC) to predict flyrock based on data from Malaysian granite quarries. Keywords include blast-induced flyrock, LSSVM, optimization, and prediction models.]

Citation: Ding, X.; Jamei, M.; Hasanipanah, M.; Abdullah, R.A.; Le, B.N. Optimized Data-Driven Models for Prediction of Flyrock due to Blasting in Surface Mines Sustainability 2023 , 15 , 8424 https://doi.org/10.3390/su 15108424 Academic Editor: Rajesh Kumar Jyothi Received: 6 April 2023 Revised: 13 May 2023 Accepted: 18 May 2023 Published: 22 May 2023 Copyright: © 2023 by the authors Licensee MDPI, Basel, Switzerland This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/) sustainability Article Optimized Data-Driven Models for Prediction of Flyrock due to Blasting in Surface Mines Xiaohua Ding 1,2 , Mehdi Jamei 3,4 , Mahdi Hasanipanah 5,6, * , Rini Asnida Abdullah 6 and Binh Nguyen Le 5,7 1 School of Mines, China University of Mining and Technology, Xuzhou 221116, China 2 State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou 221116, China 3 Faculty of Engineering, Shohadaye Hoveizeh Campus of Technology, Shahid Chamran University of Ahvaz, Dashte Azadegan 78986, Iran 4 New Era and Development in Civil Engineering Research Group, Scientific Research Center, Al-Ayen University, Thi-Qar, Nasiriyah 64001, Iraq 5 Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam 6 Department of Geotechnics and Transportation, Faculty of Civil Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia 7 School of Engineering and Technology, Duy Tan University, Da Nang 550000, Vietnam * Correspondence: hasanipanahmahdi@duytan.edu.vn Abstract: Using explosive material to fragment rock masses is a common and economical method in surface mines. Nevertheless, this method can lead to some environmental problems in the surrounding regions. Flyrock is one of the most dangerous effects induced by blasting which needs to be estimated to reduce the potential risk of damage. In other words, the minimization of flyrock can lead to sustainability of surroundings environment in blasting sites. To this aim, the present study develops several new hybrid models for predicting flyrock. The proposed models were based on a cascaded forward neural network (CFNN) trained by the Levenberg–Marquardt algorithm (LMA), and also the combination of least squares support vector machine (LSSVM) and three optimization algorithms, i.e., gravitational search algorithm (GSA), whale optimization algorithm (WOA), and artificial bee colony (ABC). To construct the models, a database collected from three granite quarry sites, located in Malaysia, was applied. The prediction values were then checked and evaluated using some statistical criteria. The results revealed that all proposed models were acceptable in predicting the flyrock. Among them, the LSSVM-WOA was a more robust model than the others and predicted the flyrock values with a high degree of accuracy Keywords: blast-induced flyrock; LSSVM; optimization; prediction models 1. Introduction Drilling and blasting is an indispensable technique for breakage and displacement of rock masses in open-pit mines. Nevertheless, some undesirable phenomena, such as ground vibration, airblast, flyrock (FR), and backbreak are produced by blasting operations [ 1 – 5 ]. Any blasting event produces a sudden ejection of rock pieces, which are referred to as “FR”. This phenomenon is one of the most hazardous environmental issues induced by blasting which may lead to various problems for humans, including fatalities [ 6 – 9 ]. As mentioned in previous studies, some blast design factors, such as burden ( B ), spacing ( S ), stemming ( ST ), weight charge ( WC ), and powder factor ( PF ), are the effective factors in the intensity of FR [ 8 – 10 ]. Aside from the aforementioned factors, the properties of the rock mass, such as rock density and uniaxial compressive strength, are considered the effective factors on the FR , called uncontrollable factors [ 9 , 10 ]. The FR can occur based on three different mechanisms, i.e., rifling, face burst, and cratering [ 11 , 12 ]. The poor ST material, the small ratio of ST to blast-hole diameter, and inadequate B are the most important causes for the rifling, cratering, and face burst mechanisms [ 9 , 13 ]. Sustainability 2023 , 15 , 8424. https://doi.org/10.3390/su 15108424 https://www.mdpi.com/journal/sustainability

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[Summary: This page discusses numerical simulations and empirical models used to study blasting mechanisms and predict flyrock. It mentions the use of artificial intelligence methods like ANN and fuzzy systems for improved prediction accuracy. The study proposes efficient hybrid models using CFNN and LSSVM with optimization algorithms (ABC, GSA, WOA) for flyrock prediction. The rest of the article's structure is outlined. It emphasizes research significance for sustainable mining practices.]

Sustainability 2023 , 15 , 8424 2 of 20 In the literature, numerical simulations are considered to be the common methods to study the blasting mechanism in rock masses. According to Kutter and Fairhurst [ 14 ], three main zones, i.e., the crushed, cracked, and elastic vibration zones, can be formed after each blasting event. Additionally, the in-situ stress has an important effect on the propagation of cracks produced by blasting. To study the failure responses of rocks, the distinct element method (DEM), finite difference method (FDM), and finite element method (FEM) have been extended in recent years by many scholars [ 15 – 20 ]. As an example, a twodimensional discrete element method was used to numerically simulate the mechanism of rock fragmentation produced by blasting in the study conducted by Hajibagherpour et al. [ 19 ]. They showed that the proposed numerical model can be effectively employed to simulate the crack propagation process around a blast-hole. Aside from numerical modelling, several empirical models have been employed to predict flyrock [ 20 ]. These empirical models have been formulated based on considering only one or two of the effective factors of flyrock. For this reason, the accuracy of the mentioned empirical models is not good enough. Therefore, the use of artificial intelligence methods can be a good solution to predict FR with a high degree of performance. Additionally, the use of artificial intelligence methods in different fields of mingling and civil engineering indicates the effectiveness of these methods for predicting and optimizing aims [ 21 – 31 ]. An artificial neural network (ANN) model was employed to predict FR in the study conducted by Monjezi et al. [ 32 ], and its performance was compared with statistical models Their results indicated the performance of ANN was better than statistical models in predicting FR . For the same purpose, Ghasemi et al. [ 33 ] employed ANN and fuzzy system (FS) and showed better prediction capability of FS over ANN. Moreover, the ANN model was compared with the adaptive neuro-fuzzy inference system (ANFIS) for the prediction of FR by Trivedi et al. [ 34 ]. They revealed higher performance in respect to accuracy of ANFIS compared with the ANN model. In another study, a genetic programming (GP) model was employed by Faradonbeh et al. [ 35 ] to predict FR . In their study, the non-linear regression models were also used for comparison aims. They concluded that the GP predicted FR with a higher performance in comparison to non-linear regression models. The GP model was also employed by Ye et al. [ 36 ] and its results was compared with a random forest model According to their results, the performance of GP was better than the random forest model The present study attempts to propose several efficient hybrid models through the cascaded forward neural network (CFNN) and also the least squares support vector machine (LSSVM) in combination with three optimization algorithms, including artificial bee colony (ABC), gravitational search algorithm (GSA), and whale optimization algorithm (WOA), for the prediction of FR The rest of this article includes the following sections. More details about the source of the database and the developed models are explained in the second section. Then, the setting parameters in the modelling processes are explained in the third section. The results and discussions are provided in the fourth section; finally, the last section presents the conclusions of the study 2. Research Significance FR is considered as an environmental and hazardous problem in mine blasting, which may result in human injuries, fatalities, property damage, and instability of slopes. Hence, a valid and reliable prediction of FR has critical implications in mitigating and controlling the adverse effects along with sustainable development and responsible mining. In other words, the control and minimization of FR can lead to sustainability of surroundings environment in blasting sites. For the aforementioned aims, the present study attempts to propose several efficient hybrid models through the CFNN and also LSSVM in combination with three optimization algorithms. To the best of our knowledge, this is the first work that predicts the FR by using the proposed models.

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[Summary: This page details the materials and methods used in the study. It describes the database collected from three granite quarry sites in Malaysia, including RQD and rock strength values. Eighty datasets with parameters like spacing, burden, stemming, powder factor, and density were used as inputs to predict flyrock (output). The LSSVM model combined with ABC, GSA, and WOA is used, along with the CFNN model for comparison. A brief explanation of LSSVM is provided.]

Sustainability 2023 , 15 , 8424 3 of 20 3. Materials and Methods 3.1. Materials The database used in this study was collected from three granite quarry sites located in Malaysia, including the Ulu Tiram, Pengerang, and the Masai quarry sites. The values of the rock quality designation (RQD) of the aforementioned quarry sites ranged from 45 to 80, 50 to 70, and 40 to 75, respectively. Additionally, the values of the rock strength ranged from 30 to 110 MPa, respectively. In total, 80 datasets including some effective parameters on the FR were used in constructing the predictive models. In this regard, the S , B , ST , PF , and density were used as the input parameters, and the FR was used as the output parameter. More details about the statistical properties of datasets will be provided in Section 5 . 3.2. Methods In this study, the LSSVM is combined with the ABC, GSA, and WOA to predict FR Additionally, the CFNN model is also used for comparison aims. In this section, the mentioned models are briefly explained 3.2.1. LSSVM Model LSSVM is a robust machine learning technique. This method was proposed as an upgraded form of the SVM, which suffered from some drawbacks in its learning stage, namely the demand in calculability and the limitation in dealing with inequality constraints. Therefore, LSSVM becomes an efficient ML technique after fixing the aforesaid issues [ 37 , 38 ]. For a regression task which aims at finding a suitable correlation that emulates the behaviour of a system defined by a set of data having inputs x = { x 1 , x 2 , . . . , x N } that x j ∈ R D and N is the number of samples in the set, and targets t defined on R as y = { y 1 , y 2 , . . . , y N } , the first step in the LSSVM method consists of formulating the following minimization problem [ 39 ]: minimize 1 2 w T w + 1 2 γ N ∑ j = 1 e 2 j s t y j = w T ϕ x j + b + e j , i = 1, 2, . . . , N (1) where e j denotes the regression error, γ represents the regularization parameter, T points out the transpose operator, w and b are the weight and bias parameters, respectively, and ϕ is a nonlinear mapping function The learning phase of LSSVM passes through finding the proper values of w and b . To this end, the formulated minimization problem is transformed into a Lagrangian function using the formula shown below [ 40 ]: L ( w , b , α , e ) = 1 2 w T w + 1 2 γ ∑ N j = 1 e 2 j − ∑ N j = 1 α j w T ϕ x j + b + e j − y j (2) where the coefficients α i are called Lagrangian multipliers. The solution of L is obtained by solving the following system of equations:              L ( w , b , α , e ) w = 0 ⇒ w = ∑ N j = 1 α j ϕ j x j L ( w , b , α , e ) b = 0 ⇒ ∑ N j = 1 α j = 0 L ( w , b , α , e ) e j = 0 ⇒ α j = γ e j , j = 1, 2, . . . , N L ( w , b , α , e ) ∂α j = 0 ⇒ w T ϕ x j + b + e j − y j = 0, j = 1, 2, . . . , N (3)

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[Summary: This page provides a detailed mathematical explanation of the LSSVM model, including the minimization problem, Lagrangian function, and kernel matrix. It highlights the importance of hyper-parameter selection (sigma^2 and gamma) for LSSVM robustness. Three metaheuristic algorithms (GSA, WOA, ABC) are introduced to tune these parameters. The Gravitational Search Algorithm (GSA) is explained in detail, outlining its principles based on Newton's law of gravity and equations for particle movement.]

Sustainability 2023 , 15 , 8424 4 of 20 The above system which defines the vanishing of the partial derivatives of L with regard to w , b , e , and α can be arranged in the following matrix scheme: 0 1 T N 1 N Ω + γ − 1 I N b α = 0 y (4) In the above equation, I N points out N × N size identity matrix, y = [ y 1 , y 2 , . . . , y N ] T , α = [ α 1 , α 2 , . . . , α N ] T , 1 N = [ 1, 1, . . . , 1 ] T , and Ω is the kernel matrix. The elements of this latter term are expressed as follows: Ω j , l = ϕ x j ϕ ( x l ) = K x j , x l (5) where K is the kernel function. Gaussian radial basis function (RBF) is among the frequently considered kernel functions in LSSVM In the last step, the gained LSSVM paradigm can predict the investigated target using the following expression: f ( x ) = ∑ N j = 1 α j K x j , x l + b (6) where ( α j , b ) are determined from Equation (4) It is worth mentioning that the robustness of LSSVM is related to the proper selection of its hyper-parameters, viz., σ 2 and γ . To do so, in the present work, three rigorous metaheuristic algorithms were suggested to tune these control parameters In this study, three optimization algorithms, including the GSA, WOA, and ABC, are used to improve the LSSVM performance. The aforementioned algorithms are briefly explained in this part (A) Gravitational search algorithm (GSA) The GSA is a metaheuristic algorithm developed by Rashedi et al. [ 41 ] based on Newton’s law of gravity [ 37 ]. The GSA is a population-based algorithm, and this means that a population of possible solutions is considered during the optimization process. The particles of the population are subjected to positions updating using the main governing equations of the algorithms. In this regard, the position of each particle is denoted by a vector x , while the force between two elements i and j at iteration g , is expressed as follows [ 41 ]: F g ij = G g M g i M g j R g ij + ε x g i − x g j (7) where ε points out a constant with a small value, R denotes the Euclidian distance between the two particles, while G represents the gravitational constant defined as: G g = G g 0 g χ 0 g χ < 1 (8) where G g 0 is the initial value of the gravitational constant. The overall force resulted from the particles of the population on each particle i is determined using the following formula [ 41 ]: F g i = ∑ N j ∈ J best , j 6 = i r 1 j F g ij (9) where J best represents a set of best particles in the population and r 1 j is a random determined uniformly over iterations from [0, 1] In another step, the motion law is considered as per following formulas [ 41 ]: a i = F g i M g i (10)

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[Summary: This page continues the explanation of the Gravitational Search Algorithm (GSA) with equations for calculating inertia mass, velocity, and position of particles. It then introduces the Whale Optimization Algorithm (WOA), another population-based algorithm mimicking the hunting process of humpback whales. Equations for updating whale positions using spiral or circular forms are presented, along with definitions of related parameters like distance, constants, and random numbers. The fitness function is also mentioned.]

Sustainability 2023 , 15 , 8424 5 of 20 where a i points out the acceleration of mass and M i is the inertia mass which is determined using the equation below: M g i = m g i ∑ N j = 1 m g j (11) and m g i = f g i − w g b g − w g (12) where f is the fitness value of the element i , and w and b represent the worst and best fitness values in the population, respectively. Finally, the velocity and the position of the elements are: v g + 1 i = r 2 i v g i + a g i (13) x g + 1 i = v g + 1 i + x g i (14) where r 2 i is a random generated uniformly from [0, 1], and v and x point out the velocity and position of elements, respectively The steps of GSA based on the stated equations are repeated until a stopping criterion is fulfilled (B) Whale optimization algorithm (WOA) The WOA is another population-based algorithm introduced by Mirjalili and Lewis [ 42 ]. The main steps and the governing equations of WOA mimic the hunting process of back whales [ 37 ]. Initially, an initial population of whales is created randomly. The positions of the whales represent possible solutions of the optimization problem. In order to evaluate the quality of these positions, a fitness function that emulates the objective function to optimize is applied. Based on the evaluation step, the whales are subjected to update their positions at a given generation ( g + 1 ) . To do so, the associated shapes of the position are changed to spiral or circular forms with respect to a probability p using the following equation [ 42 ]: X g + 1 = ( D 0 e bl cos ( 2 π t ) + X ∗ g i f p ≥ 0.5 X ∗ g − AD i f p < 0.5 (15) In the above equation, X ∗ points out the best whale which is located nearby the prey D 0 = | X i − X ∗ | represents the distance between the whale i and the prey, b is a constant for specifying the spiral shape, and l is a random number from [ − 1, 1]. The other terms of the above equation are defined as per following equations [ 42 ]: A = 2 ar − a (16) C = 2 r (17) D = | CX ∗ − X i | (18) where a is a number decreasing linearly from 2 to 0 over the distance, and r is a random from [0, 1]. According to the value of A , if it is mainly outside the interval [ − 1, 1], a circular form is considered for upgrading the positions based on a randomly selected whale X g r The following equation shows this process: X g + 1 = X g r − AD (19) The new positions obtained after carrying out the update of the shapes are assessed using the fitness function. Lastly, if the best whale shows an enhancement in its fitness values, it will change its position to this newest one, otherwise, the best existing position will be conserved.

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[Summary: This page continues describing the Whale Optimization Algorithm (WOA) and introduces the Artificial Bee Colony (ABC) algorithm, a swarm-based metaheuristic algorithm that mimics honeybee foraging behavior. It explains the roles of employed, onlooker, and scout bees in the search process. Equations for updating bee positions, calculating probability, and scouting are provided. The optimum solution is represented by the fittest bee. The steps are repeated until a stopping condition is reached.]

Sustainability 2023 , 15 , 8424 6 of 20 The described steps of this optimization algorithm are repeated until a stopping criterion is achieved (C) Artificial Bee Colony (ABC) The ABC is an intelligent swarm-based metaheuristic algorithm proposed by Karaboga [ 43 ] As indicated in its appellation, ABC emulates the steps performed by honeybees as they search for nectar sources. In this regard, three groups, including employed, onlookers, and scout bees are considered in this process. The role of employed group is to amass the information and expose it to the onlooker group. The scout group consists of changing the positions once no improvement is noticed in some sources of bees The main steps of ABC are given below [ 44 ]: - An initial population of bees is generated randomly. Each bee has its own position x The numbers of employed and onlookers are the same in the population. A fitness function is considered for assessing the quality of the bees - Employed bees: this step consists of updating the positions of bees at the generation ( g + 1) using the following equation: x g + 1 i = x g i + ϑ i x g i − x g ω (20) where ϑ i is a random from [0, 1] and ω ∈ { 1, 2, . . . , colony size } ω 6 = i Afterward, the quality of each new position is examined using the fitness function, and if an improvement is obtained, this new position is conserved, otherwise, it is abandoned - Onlooker bees: by carrying out the previous step which emulates the exploitation phase, the gained information by the employed bees is exposed to the onlookers, which select the proper ones by applying the following equation bases on the probability P : P i = f t i ∑ E i = 1 f t i (21) where f t points out the fitness value and E represents the number of employed bees. As in the case of employed bees, if an improvement is obtained, this new position is conserved, otherwise, it is abandoned - Scout bees: this step consists of randomly changing the position of a given employed bee after a defined number of generations if it does not show any improvements in its fitness quality The optimum solution of the problem is represented by the fittest bee. The abovedescribed steps are recurring until a stopping condition is reached 3.2.2. CFNN Model The CFNN is a type of ANN which is recognized by its flexible-based structure [ 45 ]. This advantage allows CFNN to generate accurate predictive models for many systems with different degrees of complexity. The structure of CFNN neurons is distributed into three kinds of layers, including input, hidden, and output layers [ 46 ]. The input layer receives the data, then this latter is transformed and processed in one or more hidden layers using the so-called activation functions (such as tansig and logsig ), while the results of the paradigm are obtained from the output layer. The number of hidden layers and their involved neurons depend on the complexity of the system as one hidden layer is generally enough for low to medium complicated cases, while more than one hidden layer is requested for highly complex cases. CFNN is characterized by its specific cascaded scheme for linking the neurons to the others [ 46 ]. This scheme is ensured by linking each neuron from a preceding layer to the nodes of the subsequent layers [ 46 ]. As the other kinds of ANN, the learning phase of CFNN aims at achieving the suitable weight and bias values of its architecture. Backpropagation-based algorithms, such as the

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[Summary: This page explains the CFNN model, a type of ANN with a flexible structure consisting of input, hidden, and output layers. The cascaded scheme for linking neurons is described. The Levenberg-Marquardt algorithm (LMA) is used for optimizing bias and weights. The differences between CFNN and LSSVM are highlighted. It describes the model performance evaluation with Average Absolute Relative Error (AARE), Coefficient of Determination (R^2), and Root Mean Square Error (RMSE).]

Sustainability 2023 , 15 , 8424 7 of 20 Levenberg–Marquardt algorithm (LMA), are known to be highly efficient for this kind of optimization. In this investigation, LMA algorithms were considered in the optimization of the bias and weights of CFNN. More information about LMA can be found in published literature [ 47 , 48 ]. It is worth mentioning that the considered soft computing approaches in this study, namely CFNN and LSSVM, differ from each other mainly on the learning strategy where in LSSVM, the learning process is done after the formulation of the minimization problem (shown in Equation (1)) and then the problem is resolved by finding the control parameters of the model, while in CFNN, the learning approach is gained by finding the suitable topology and the appropriate weights linking between the neurons of different layers until reaching the low function error (such as root mean square error) value 3.2.3. Model Performance Evaluation As stated in the previous section, the modelling task of FR using CFNN and LSSVM was extended in this study by investigating the suitable input parameters that can give the most accurate predictions of this vital factor. Before showing the main finding of the modelling tasks using the aforesaid ML models, it is worth mentioning that during the performance evaluation of the models, the following statistical indexes were calculated using the equations shown below [ 1 , 4 , 5 , 49 – 52 ]: Average Absolute Relative Error ( AARE ): AARE % = 1 N ∑ N i = 1 FR imea − FR i pred FR imea × 100 (22) Coefficient of Determination ( R 2 ): R 2 = 1 − ∑ N i = 1 FR imea − FR i pred 2 ∑ N i = 1 FR i pred − FR 2 (23) Root Mean Square Error ( RMSE ): RMSE = r 1 N ∑ N i = 1 FR imea − FR i pred 2 (24) In the above equations, the subscripts mea and pred denote the measured and estimated FR , respectively, FR mean of FR values, and N points out the number of samples 4. Development of Predictive Models The main purpose of the suggested ML learning methods in this study was to deliver robust models that can estimate the FR under different circumstances. For a better investigation, several input parameters were considered in each of the proposed paradigms Accordingly, six different schemes were involved in the development of these ML-based predictive models. These schemes are summarized in the following equations: ( M 1 ) FR = f ( S , B , ST , PF , Density ) (25) ( M 2 ) FR = f ( S , B , ST , PF ) (26) ( M 3 ) FR = f ( S , B , ST , Density ) (27) ( M 4 ) FR = f ( S , B , PF , Density ) (28) ( M 5 ) FR = f ( S , ST , PF , Density ) (29)

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[Summary: This page describes the development of predictive models using CFNN-LMA and LSSVM-metaheuristic algorithms (LSSVM-WOA, LSSVM-GSA, LSSVM-ABC) to estimate flyrock. Six different schemes were used with various combinations of input parameters. The normalization procedure of the database using a specific equation is explained to improve the performance of the ML techniques. A workflow of the suggested CFNN paradigm is displayed.]

Sustainability 2023 , 15 , 8424 8 of 20 ( M 6 ) FR = f ( B , ST , PF , Density ) (30) In order to properly implement CFNN-LMA and the proposed hybridization LSSVMmetaheuristic algorithms, including the LSSVM-WOA, LSSVM-GSA, and LSSVM-ABC models, some necessary steps were carried out as shown in the two flowcharts of Figures 1 and 2 , respectively. According to these flowcharts, the first step consisted of normalizing the database. This step significantly improves the performance of the considered ML techniques. The normalization procedure of the database is given in the following equation: x n = 2 ( x i − x min ) ( x max − x min ) − 1 (31) where x and x n point out the variable and the normalized value, respectively, while x max and x min represent the maximum and minimum values of the variable, respectively Sustainability 2023 , 15 , x FOR PEER REVIEW 8 of 20 considered ML techniques The normalization procedure of the database is given in the fol ‐ lowing equation: {?} 1 (31) where x and {?} point out the variable and the normalized value, respectively, while {?} and {?} represent the maximum and minimum values of the variable, respectively Figure 1. The work fl ow of the suggested CFNN paradigm Figure 1. The workflow of the suggested CFNN paradigm.

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[Summary: This page shows the work flow of the suggested LSSVM paradigms. After normalization, the data was divided into train and test sets. The aim of these two groups was to train the models (train set) and certify their robustness of unseen measurements (test set). During the learning phase of the CFNN- and LSSVM-based models, their control parameters were investigated using the above-discussed algorithms and some other techniques. The constraints and/or evaluation of overfitting were considered.]

Sustainability 2023 , 15 , 8424 9 of 20 Sustainability 2023 , 15 , x FOR PEER REVIEW 9 of 20 Figure 2. The work fl ow of the suggested LSSVM paradigms After performing the normalization of the data, the la tt er was divided into train and test sets The aim of these two groups was to train the models (train set) and certify their robustness of unseen measurements (test set) These two sets covered 80% and 20% of the whole measurements, respectively During the learning phase of the CFNN ‐ and LSSVM ‐ based models, their control parameters were investigated using the above ‐ discussed algorithms and some other techniques In this regard, the trial and error method was considered for selecting the best topology of CFNN, while LMA was ap ‐ plied for optimizing the weights and bias values of the network For the LSSVM model, three metaheuristic algorithms including ABC, GSA, and WOA were implemented in the optimization of the two impacting LSSVM control parameters, namely {?} and {?} It is necessary to add that it was proven in some previous works that it is more suitable to consider some speci fi c trust region algorithms such as Levenberg–Marquardt algorithms rather than applying metaheuristic algorithms in the training phase of some feedforward networks such as MLP and CFNN [53] However, for many other soft ‐ computing ap ‐ proaches such as LSSVM and SVM, metaheuristic algorithms are much more appropriate for fi nding the control parameters of these techniques [54] Table 1 reports the main se tt ing of these metaheuristic algorithms In our suggested work fl ows (Figures 1 and 2), Figure 2. The workflow of the suggested LSSVM paradigms After performing the normalization of the data, the latter was divided into train and test sets. The aim of these two groups was to train the models (train set) and certify their robustness of unseen measurements (test set). These two sets covered 80% and 20% of the whole measurements, respectively. During the learning phase of the CFNNand LSSVM-based models, their control parameters were investigated using the abovediscussed algorithms and some other techniques. In this regard, the trial and error method was considered for selecting the best topology of CFNN, while LMA was applied for optimizing the weights and bias values of the network. For the LSSVM model, three metaheuristic algorithms including ABC, GSA, and WOA were implemented in the optimization of the two impacting LSSVM control parameters, namely γ and σ 2 . It is necessary to add that it was proven in some previous works that it is more suitable to consider some specific trust region algorithms such as Levenberg–Marquardt algorithms rather than applying metaheuristic algorithms in the training phase of some feedforward networks such as MLP and CFNN [ 53 ]. However, for many other soft-computing approaches such as LSSVM and SVM, metaheuristic algorithms are much more appropriate for finding the control parameters of these techniques [ 54 ]. Table 1 reports the main setting of these metaheuristic algorithms. In our suggested workflows (Figures 1 and 2 ), the constraints and/or evalua-

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[Summary: This page presents Table 1, which displays the control parameters of the three employed metaheuristic algorithms (ABC, GSA, WOA) and their values. It then transitions into the results and discussion section, starting with exploratory analysis. It emphasizes the importance of statistical data description in ML-based modeling. Table 2 lists the statistical properties of the datasets, confirming a pseudo-normal distribution. Figure 3 demonstrates the Pearson correlation coefficients.]

Sustainability 2023 , 15 , 8424 10 of 20 tion of overfitting were considered by checking the accuracy of the paradigms during both training and testing phases. It is clear from the statistical evaluation of the models that if the prediction accuracy of the latter is very satisfactory during the training and testing phases, the overfitting issue is avoided Table 1. The considered control parameters of the three employed metaheuristic algorithms Algorithm Parameter Value ABC Number of employer bees 20 Number of onlooker bees 20 Number of generations 30 Number of generations to scout bees 4 GSA r 1 j and r 2 j [0, 1] Number of generations 30 Number of individuals 40 WOA a 2 to 0 r [0, 1] Number of generations 30 Number of whales 40 5. Results and Discussion 5.1. Exploratory Analysis The optimal strategy for solving the high non-linear problems significantly depend on the behavior of the dataset used in the simulation process. Thus, the statistical data description is one of the most crucial tasks of the pre-processing stage in ML-based modelling in engineering problems. Table 2 lists the statistical properties of datasets implemented in the FR predicting procedure. The low values of skewness and kurtosis confirmed that all inputs and targets are categorized as a pseudo-normal distribution. Figure 3 demonstrates the Pearson correlation coefficients in form of a correlogram. It can be concluded that the “ S ” parameter with respect to the largest correlation coefficient (0.65) has the most significance in prediction of the FR value Sustainability 2023 , 15 , x FOR PEER REVIEW 11 of 20 Figure 3. Correlogram for assessing the Pearson correlation coe ffi cient between input and target parameters Green: Histogram, Red: Regression line, and Blue: Distribution points As stated before, the database considered in this study was divided into training and testing sets The fi rst set is applied in the models’ development, while the test set is de ‐ voted to the validation and investigation of the accuracy behavior of the established models when dealing with unseen measurements 5.2. Modelling Results By performing the steps described in the previous sections, it was found that 3 hid ‐ den layers with tansig as an activation function, and 12, 11, and 9 neurons in each of them, respectively, represented the proper CFNN topology in all of the six schemes For LSSVM models, the achieved {?} and {?} values using the ABC, GSA, and WOA ranged between 403.15 to 1847.43 and 35,479,174.56 to 67,688,321.04, respectively The statistical evaluation of the performance of the obtained ML ‐ based models with respect to the stated six schemes in the previous sections is shown in Table 3 In this table, statistical criteria, namely AARE , R 2 , and RMSE are reported for the training set, the test set, and the whole dataset According to this table, and based on the schemes, it can be seen that M 1 is the best one, followed by M 2 In the combination of M 1 including all inputs for the testing phase, the LSSVM ‐ WOA in terms of ( R 2 = 0.999, RMSE = 3.4209 m, and AARE = 1.3017) was identi fi ed as the superior predictive model, followed by CFNN ‐ LMA ( R 2 = 0.9347, RMSE = 16.5215 m, and AARE = 7.512), LSSVM ‐ GSA ( R 2 = 0.904, RMSE = 16.1775 m, and AARE = 5.5193), and LSSVM ‐ ABC ( R 2 = 0.9049, RMSE = 19.439 m, and AARE = 8.0032), respectively In the M 2 (in testing phase), as the second ‐ best combination, the LSSVM ‐ WOA with respect to the highest R 2 (0.9896) and smallest RMSE (10.4268) outperformed the other models The result assessment demonstrated that M 6 on account of poorest performance ( R 2 = 0.3616 and RMSE = 58.5744 for the LSSVM ‐ WOA) was rec ‐ ognized as the worst scheme regardless of the ML type Typically, it can be understood from this remark that S is the most impacting input parameter on FR as its exclusion from the input variables ( M 6 ) caused the worst prediction performance regardless of the type of ML techniques, while density has a small e ff ect on FR since its elimination from the input parameters ( M 2 ) did not signi fi cantly a ff ect the degree of prediction accuracy In Figure 3. Correlogram for assessing the Pearson correlation coefficient between input and target parameters. Green: Histogram, Red: Regression line, and Blue: Distribution points.

[[[ p. 11 ]]]

[Summary: This page presents Figure 3, a correlogram assessing the Pearson correlation coefficient between input and target parameters. It states that the database was divided into training and testing sets. The modelling results section indicates that 3 hidden layers with tansig activation function and 12, 11, and 9 neurons represented the proper CFNN topology. The statistical evaluation of the performance of the obtained ML-based models with respect to the stated six schemes is shown in Table 3.]

Sustainability 2023 , 15 , 8424 11 of 20 Table 2. Descriptive statistics of all features used in modelling the FR Metric/Feature S (m) B (m) ST (m) PF (kg/m 3 ) Density (gr/cm 3 ) FR (m) Minimum 2.65 1.5 1.7 0.67 2.3 61 Maximum 4 3.2 3.6 1.05 2.8 334 Mean 3.324 2.415 2.171 0.8908 2.579 223.5 Std. Deviation 0.4228 0.4776 0.4022 0.113 0.1684 64.61 CV 12.72% 19.78% 18.53% 12.69% 6.529% 28.91% Skewness − 0.2032 0.2017 1.608 − 0.2148 − 0.2942 − 0.5848 Kurtosis − 1.556 − 1.518 2.82 − 1.058 − 1.247 − 0.1065 As stated before, the database considered in this study was divided into training and testing sets. The first set is applied in the models’ development, while the test set is devoted to the validation and investigation of the accuracy behavior of the established models when dealing with unseen measurements 5.2. Modelling Results By performing the steps described in the previous sections, it was found that 3 hidden layers with tansig as an activation function, and 12, 11, and 9 neurons in each of them, respectively, represented the proper CFNN topology in all of the six schemes. For LSSVM models, the achieved σ 2 and γ values using the ABC, GSA, and WOA ranged between 403.15 to 1847.43 and 35,479,174.56 to 67,688,321.04, respectively The statistical evaluation of the performance of the obtained ML-based models with respect to the stated six schemes in the previous sections is shown in Table 3 . In this table, statistical criteria, namely AARE , R 2 , and RMSE are reported for the training set, the test set, and the whole dataset. According to this table, and based on the schemes, it can be seen that M 1 is the best one, followed by M 2 . In the combination of M 1 including all inputs for the testing phase, the LSSVM-WOA in terms of ( R 2 = 0.999, RMSE = 3.4209 m, and AARE = 1.3017) was identified as the superior predictive model, followed by CFNN-LMA ( R 2 = 0.9347, RMSE = 16.5215 m, and AARE = 7.512), LSSVM-GSA ( R 2 = 0.904, RMSE = 16.1775 m, and AARE = 5.5193), and LSSVM-ABC ( R 2 = 0.9049, RMSE = 19.439 m, and AARE = 8.0032), respectively. In the M 2 (in testing phase), as the second-best combination, the LSSVM-WOA with respect to the highest R 2 (0.9896) and smallest RMSE (10.4268) outperformed the other models. The result assessment demonstrated that M 6 on account of poorest performance ( R 2 = 0.3616 and RMSE = 58.5744 for the LSSVM-WOA) was recognized as the worst scheme regardless of the ML type. Typically, it can be understood from this remark that S is the most impacting input parameter on FR as its exclusion from the input variables ( M 6 ) caused the worst prediction performance regardless of the type of ML techniques, while density has a small effect on FR since its elimination from the input parameters ( M 2 ) did not significantly affect the degree of prediction accuracy. In addition, it can also be deduced that for each of the six schemes, the LSSVM-WOA yielded more accurate predictions compared with the other LSSVM-metaheuristic algorithms and the CFNN-LMA. According to Table 3 , it was found that M 1 outperformed other combinations followed by M 2 , M 4 , M 3 , M 5 , and M 6 , respectively. Additionally, it can be said that the LSSVM-WOA in all input combinations was the best predictive model developed in this study for prediction of FR . For better comparison between the predictive performances of the provided models in all combinations, the probability density function violin plots are exhibited in Figure 4 . According to this figure, considering the best agreement between measured and predicted values of FR , it can be clearly implied that the LSSVM-WOA was the superior model for accurately estimating FR , the CFNN-LMA was identified as the second-best model, and LSSVM-ABC yielded the worst results in all combinations. Regarding the mentioned analysis, the combination of M 1 was kept for further performance investigation and validations. It is necessary to add that

[[[ p. 12 ]]]

[Summary: This page provides the first part of Table 3, which presents the statistical evaluation of the performance of the suggested ML-based models with respect to the six schemes, reporting AARE, R^2, and RMSE for the training set, the test set, and the whole dataset. The results indicate that M1 is the best scheme, followed by M2. For M1, LSSVM-WOA was identified as the superior predictive model, followed by CFNN-LMA, LSSVM-GSA, and LSSVM-ABC.]

Sustainability 2023 , 15 , 8424 12 of 20 in order to confirm that the ANN scheme did not suffer from the overfitting issue, a 4-fold cross-validation was performed on our best ANN paradigm (the case of M 1 ) to assess the generalization of the model when dealing with new sets of data. To do so, the database was randomly divided into 4 folds, then, the modelling was done by considering a sole fold as the test sub-data and devoting the rest for the training phase. In order to swap between the folds involved in the training and testing phases, the aforesaid step was repeated 4 times The results gained from the 4-fold cross-validation are reported in Table 4 . As can be seen, the consistency of the model is confirmed for all the folds, thus, the overfitting issue is avoided Table 3. Performance of the suggested ML-based models with respect to the six schemes Scheme Model Statistical Criteria Train Data Test Data All Data M 1 CFNN-LMA R 2 0.9875 0.9347 0.977 AARE 2.5163 7.512 3.5154 RMSE 7.2292 16.5215 9.8184 LSSVM-ABC R 2 0.9867 0.9049 0.971 AARE 3.0419 8.0032 4.0341 RMSE 7.4089 19.439 10.9311 LSSVM-GSA R 2 0.9828 0.904 0.967 AARE 3.4215 5.5193 3.8411 RMSE 8.7308 16.1775 10.6453 LSSVM-WOA R 2 0.9926 0.9991 0.9943 AARE 1.6473 1.3017 1.5782 RMSE 7.4847 3.4209 6.8671 M 2 CFNN-LMA R 2 0.9812 0.9366 0.972 AARE 2.9261 8.5748 4.0558 RMSE 8.4645 20.2612 11.8077 LSSVM-ABC R 2 0.9769 0.9235 0.9675 AARE 3.7643 7.083 4.428 RMSE 9.8655 16.7483 11.5743 LSSVM-GSA R 2 0.9754 0.9054 0.9614 AARE 4.254 6.5356 4.7103 RMSE 10.3962 18.0443 12.312 LSSVM-WOA R 2 0.9871 0.9896 0.9875 AARE 2.6662 2.8723 2.7074 RMSE 10.105 10.4268 10.1702 M 3 CFNN-LMA R 2 0.883 0.9172 0.89 AARE 7.2573 8.2441 7.4546 RMSE 21.9097 18.6501 21.2977 LSSVM-ABC R 2 0.9191 0.7622 0.8811 AARE 6.7642 12.4379 7.8989 RMSE 17.7366 34.5376 22.1413 LSSVM-GSA R 2 0.8874 0.7979 0.8714 AARE 7.8757 13.615 9.0236 RMSE 21.7035 27.6908 23.0259 LSSVM-WOA R 2 0.9625 0.9398 0.9305 AARE 6.6657 21.8618 9.7049 RMSE 17.5076 43.8141 25.0828

[[[ p. 13 ]]]

[Summary: This page continues Table 3, which presents the statistical evaluation of the performance of the suggested ML-based models with respect to the six schemes, reporting AARE, R^2, and RMSE for the training set, the test set, and the whole dataset for M4 and M5. M6 has the worst performance, suggesting S is the most impacting input parameter on FR, while density has a small effect. LSSVM-WOA yielded more accurate predictions compared with the other LSSVM-metaheuristic algorithms and the CFNN-LMA.]

Sustainability 2023 , 15 , 8424 13 of 20 Table 3. Cont Scheme Model Statistical Criteria Train Data Test Data All Data M 4 CFNN-LMA R 2 0.8878 0.8706 0.8856 AARE 6.9643 10.5219 7.6758 RMSE 21.6209 22.0891 21.7153 LSSVM-ABC R 2 0.892 0.8572 0.8849 AARE 7.0333 9.8644 7.5995 RMSE 20.9307 24.9094 21.7846 LSSVM-GSA R 2 0.8689 0.8748 0.8707 AARE 8.1285 11.6169 8.8262 RMSE 22.7463 24.3938 23.0852 LSSVM-WOA R 2 0.9921 0.9201 0.9777 AARE 2.7384 14.8704 5.1648 RMSE 8.0666 31.6042 15.8689 M 5 CFNN-LMA R 2 0.8879 0.8456 0.8791 AARE 7.6983 11.2721 8.413 RMSE 21.3743 25.7841 22.326 LSSVM-ABC R 2 0.8891 0.8376 0.8823 AARE 8.3536 7.5541 8.1937 RMSE 22.1859 21.3895 22.0289 LSSVM-GSA R 2 0.8983 0.831 0.8825 AARE 6.6676 11.6499 7.6641 RMSE 19.9291 28.846 22.0035 LSSVM-WOA R 2 0.8979 0.7985 0.8859 AARE 12.374 13.7799 12.6551 RMSE 29.5911 30.7061 29.8175 M 6 CFNN-LMA R 2 0.4324 0.3195 0.4186 AARE 17.817 30.9799 20.4496 RMSE 46.3091 58.3475 48.9542 LSSVM-ABC R 2 0.4856 0.1575 0.4327 AARE 17.9507 30.1723 20.395 RMSE 44.6322 61.0195 48.356 LSSVM-GSA R 2 0.5574 0.4669 0.4329 AARE 18.587 24.6491 19.7994 RMSE 44.7295 60.6898 48.3449 LSSVM-WOA R 2 0.806 0.3616 0.7228 AARE 15.5962 22.1002 16.897 RMSE 40.172 58.5744 44.466

[[[ p. 14 ]]]

[Summary: This page continues Table 3, which presents the statistical evaluation of the performance of the suggested ML-based models with respect to the six schemes, reporting AARE, R^2, and RMSE for the training set, the test set, and the whole dataset for M6. The results show that M1 outperformed other combinations followed by M2, M4, M3, M5, and M6, respectively. The LSSVM-WOA in all input combinations was the best predictive model developed in this study for prediction of FR. Figure 4 shows the probability density function violin plots.]

Sustainability 2023 , 15 , 8424 14 of 20 Sustainability 2023 , 15 , x FOR PEER REVIEW 14 of 20 Figure 4. Probability density function of the predictive models of M 1 for prediction of FR for all datasets used in the simulation process Table 4. Results of the 4 ‐ fold cross ‐ validation for the CFNN ‐ LMA model ( M 1 scheme) Overall R 2 Overall RMSE Fold 1 0.9759 9.8664 Fold 2 0.9761 9.8601 Fold 3 0.9754 9.9361 Fold 4 0.9762 9.8597 In order to extend the examination of the accuracy of the best implemented models, some graphical evaluation techniques were considered Figure 5 shows the physical trend variation and cross plots related to the M 1 which illustrate a comparison of the measured and predicted FR values during both the training and testing phases Based on the sca tt er plots, a tight cloud of points is located nearby the line Y = X for all datasets This means that the LSSVM ‐ WOA can predict FR values with a great degree of accuracy as its predictions are very close to the perfect case shown by the unit ‐ slop line The left side of Figure 6 shows the ability of the predictive models to capture the non ‐ linearity behaviour of the datasets The LSSVM ‐ WOA yields the best agreement with the meas ‐ ured FR compared with other LSSVM models and the CFNN ‐ LMA model Figure 4. Probability density function of the predictive models of M 1 for prediction of FR for all datasets used in the simulation process Table 4. Results of the 4-fold cross-validation for the CFNN-LMA model ( M 1 scheme) Overall R 2 Overall RMSE Fold 1 0.9759 9.8664 Fold 2 0.9761 9.8601 Fold 3 0.9754 9.9361 Fold 4 0.9762 9.8597 In order to extend the examination of the accuracy of the best implemented models, some graphical evaluation techniques were considered. Figure 5 shows the physical trend variation and cross plots related to the M 1 which illustrate a comparison of the measured and predicted FR values during both the training and testing phases. Based on the scatter plots, a tight cloud of points is located nearby the line Y = X for all datasets. This means that the LSSVM-WOA can predict FR values with a great degree of accuracy as its predictions are very close to the perfect case shown by the unit-slop line. The left side of Figure 6 shows the ability of the predictive models to capture the non-linearity behaviour of the datasets The LSSVM-WOA yields the best agreement with the measured FR compared with other LSSVM models and the CFNN-LMA model Another visual tool for inspecting the reliability of the LSSVM-WOA paradigm is dealing with the relative deviation (RD%) distribution diagram that is exhibited in Figure 6 . The quartiles of RD for 25% and 75% of datasets are listed in Table 5 . The LSSVM-WOA model, owing to having the least values of Q 25% = − 0.5566, Q 75% = 1.093, and IQR = 1.650, yielded more reliable outcomes in comparison with the CFNN-LMA (Q 25% = − 2.976, Q 75% = 2.105, and IQR = 5.081), LSSVM-ABC (Q 25% = − 2.778, Q 75% = 2.504, and IQR = 5.282), and LSSVM- GSA (Q 25% = − 2.712, Q 75% = 2.716, and IQR = 5.428), respectively. Obviously, the above

[[[ p. 15 ]]]

[Summary: This page shows Figure 4, the probability density function of the predictive models of M1 for prediction of FR for all datasets used in the simulation process. Table 4 shows results of the 4-fold cross-validation for the CFNN-LMA model (M1 scheme). It indicates the consistency of the model for all the folds, thus, the overfitting issue is avoided. The examination of the accuracy of the best implemented models were extended using graphical evaluation techniques.]

Sustainability 2023 , 15 , 8424 15 of 20 diagnostic analysis reveals that the LSSVM-WOA model has very low prediction errors regardless of the considered conditions Sustainability 2023 , 15 , x FOR PEER REVIEW 15 of 20 Figure 5. Comparing the predicted and measured FR values in the form of the cross plot and trend variation plot for all datasets Another visual tool for inspecting the reliability of the LSSVM ‐ WOA paradigm is dealing with the relative deviation (RD%) distribution diagram that is exhibited in Fig ‐ ure 6 The quartiles of RD for 25% and 75% of datasets are listed in Table 5 The LSSVM ‐ WOA model, owing to having the least values of Q 25% = − 0.5566, Q 75% = 1.093, and IQR = 1.650, yielded more reliable outcomes in comparison with the CFNN ‐ LMA (Q 25% = − 2.976, Q 75% = 2.105, and IQR = 5.081), LSSVM ‐ ABC (Q 25% = − 2.778, Q 75% = 2.504, and IQR = 5.282), and LSSVM ‐ GSA (Q 25% = − 2.712, Q 75% = 2.716, and IQR = Figure 5. Comparing the predicted and measured FR values in the form of the cross plot and trend variation plot for all datasets.

[[[ p. 16 ]]]

[Summary: This page presents Figure 5, which compares the predicted and measured FR values in the form of the cross plot and trend variation plot for all datasets. It indicates that the LSSVM-WOA can predict FR values with a great degree of accuracy. The left side of Figure 6 shows the ability of the predictive models to capture the non-linearity behavior of the datasets. Figure 6 also shows the relative deviation (RD%) distribution diagram.]

Sustainability 2023 , 15 , 8424 16 of 20 Sustainability 2023 , 15 , x FOR PEER REVIEW 16 of 20 5.428), respectively Obviously, the above diagnostic analysis reveals that the LSSVM ‐ WOA model has very low prediction errors regardless of the considered condi ‐ tions Figure 6. Relative errors of prediction models versus the measured FR values Table 5. Quartile of RD for 25% and 75% of datasets Model CFNN ‐ LMA LSSVM ‐ ABC LSSVM ‐ GSA LSSVM ‐ WOA Q 25% ‐ RD% − 0.5566 − 2.778 − 2.712 − 2.976 Q 75% ‐ RD% 1.093 2.504 2.716 2.105 IQR ‐ RD% 1.650 5.282 5.428 5.081 Lastly, Figure 7 demonstrates the 3 D surface of RD variation concerning the LSSVM ‐ WOA versus the S and PF , as the two most signi fi cant variables, to assess the re ‐ liability seeking zone for estimating the FR The RD variation reveals that the most relia ‐ ble and accurate results are obtained in the ranges of 3 ≤ S ≤ 3.5 and 0.8 ≤ PF ≤ 1.1 Figure 7. RD variation versus S and PF for LSSVM ‐ WOA model (Red points: Samples in distribu ‐ tion) Figure 6. Relative errors of prediction models versus the measured FR values Table 5. Quartile of RD for 25% and 75% of datasets Model CFNN-LMA LSSVM-ABC LSSVM-GSA LSSVM-WOA Q 25% -RD% − 0.5566 − 2.778 − 2.712 − 2.976 Q 75% -RD% 1.093 2.504 2.716 2.105 IQR-RD% 1.650 5.282 5.428 5.081 Lastly, Figure 7 demonstrates the 3 D surface of RD variation concerning the LSSVM- WOA versus the S and PF , as the two most significant variables, to assess the reliability seeking zone for estimating the FR . The RD variation reveals that the most reliable and accurate results are obtained in the ranges of 3 ≤ S ≤ 3.5 and 0.8 ≤ PF ≤ 1.1 Sustainability 2023 , 15 , x FOR PEER REVIEW 16 of 20 5.428), respectively Obviously, the above diagnostic analysis reveals that the LSSVM ‐ WOA model has very low prediction errors regardless of the considered condi ‐ tions Figure 6. Relative errors of prediction models versus the measured FR values Table 5. Quartile of RD for 25% and 75% of datasets Model CFNN ‐ LMA LSSVM ‐ ABC LSSVM ‐ GSA LSSVM ‐ WOA Q 25% ‐ RD% − 0.5566 − 2.778 − 2.712 − 2.976 Q 75% ‐ RD% 1.093 2.504 2.716 2.105 IQR ‐ RD% 1.650 5.282 5.428 5.081 Lastly, Figure 7 demonstrates the 3 D surface of RD variation concerning the LSSVM ‐ WOA versus the S and PF , as the two most signi fi cant variables, to assess the re ‐ liability seeking zone for estimating the FR The RD variation reveals that the most relia ‐ ble and accurate results are obtained in the ranges of 3 ≤ S ≤ 3.5 and 0.8 ≤ PF ≤ 1.1 Figure 7. RD variation versus S and PF for LSSVM ‐ WOA model (Red points: Samples in distribu ‐ tion) Figure 7. RD variation versus S and PF for LSSVM-WOA model. (Red points: Samples in distribution) 6. Conclusions FR is one of the most adverse effects induced by blasting in surface mines. In this study, an attempt was made to predict blast-induced FR through hybridizing three optimization

[[[ p. 17 ]]]

[Summary: This page continues to discuss Figure 6, emphasizing the LSSVM-WOA model's reliability. It references Table 5, which lists quartiles of RD. It notes that the LSSVM-WOA model yielded more reliable outcomes compared to CFNN-LMA, LSSVM-ABC, and LSSVM-GSA. The page then transitions into the conclusions of the study, which centers on predicting blast-induced FR through hybridizing optimization algorithms with the LSSVM model.]

Sustainability 2023 , 15 , 8424 17 of 20 algorithms including the ABC, GSA, and WOA with the LSSVM model. In addition, CFNN- LMA, as a powerful tool for the prediction aims, was developed. For developing the models, six different schemes based on different combinations of input parameters were employed and in total, twenty-four different models were constructed. After that, three statistical indexes, i.e., AARE , R 2 , and RMSE , were used to check the performance of the models and to compare their results Some conclusions are drawn as follows: the results indicated that among the total constructed models, the LSSVM-WOA model was the most accurate model in all six schemes compared with the CFNN-LMA, LSSVM-GSA, and LSSVM-ABC models. The most accurate results of the LSSVM-WOA ( AARE = 1.3017, R 2 = 0.9991 and RMSE = 3.4209), LSSVM- GSA ( AARE = 5.5193, R 2 = 0.904 and RMSE = 16.1775), and CFNN-LMA ( AARE = 7.512, R 2 = 0.9347 and RMSE = 16.5215) were obtained from the first scheme, while that for the LSSVM-ABC model ( AARE = 7.083, R 2 = 0.9235 and RMSE = 16.7483) was obtained from the second scheme. It is important to note that the above results were related to the testing phase. On the other hand, the sixth scheme had the worst performance. In this scheme, the S parameter was removed from the modelling. Therefore, it can be suggested that the S was an effective parameter in the modelling. Additionally, according to RD%, the LSSVM-WOA model had very low prediction errors regardless of the considered conditions. The presented results in this study cannot be compared with results of the previous studies because different fields investigation as well as different range of input parameters were used in the previous studies. Nevertheless, for a comparison with the literature, the LSSVM-WOA presented in this study predicted the FR with a very good R 2 , while Koopialipoor et al. [ 55 ], Faradonbeh et al. [ 56 ], Zhou et al. [ 57 ], Nguyen et al. [ 58 ], and Marto et al. [ 59 ] predicted the FR with an R 2 of 0.959, 0.924, 0.944, 0.986, and 0.981, respectively. The aforementioned results indicate the effectiveness of the LSSVM-WOA model in predicting the FR It is worth mentioning that the proposed models herein are specific to studied cases and the use of these models in other surface mines requires some modification based on blasting and mining conditions. However, our best implemented model can predict the FR with high accuracy and the paradigm can be applied for cases filling the applicability conditions considered in this work, namely by respecting the maximum and minimum values of the involved input parameters For future works, it can be recommended to use other optimization algorithms, such as seagull optimization algorithm (SOA), sparrow search algorithm (SSA), loin swarm optimization (LSO), and moth-flame optimization (MFO) algorithms, in combination with CFNN and LSSVM models Author Contributions: Conceptualization, M.H.; Methodology, X.D. and M.J.; Validation, X.D., M.J. and M.H.; Investigation, M.H. and B.N.L.; Data curation, M.H.; writing—original draft preparation, X.D., M.J., M.H., R.A.A. and B.N.L.; writing—review and editing, X.D., M.J., M.H., R.A.A. and B.N.L.; Supervision, M.H. and R.A.A. All authors have read and agreed to the published version of the manuscript Funding: This paper is supported by the National Natural Science Foundation of China (Grant No. 52174131) Institutional Review Board Statement: Not applicable Informed Consent Statement: Not applicable Data Availability Statement: The data used in this study may be available on request from the corresponding author Acknowledgments: The authors would like to thank Danial Jahed Armaghani for providing the information and facilities required for conducting this research Conflicts of Interest: The authors have no conflict of interest to declare that are relevant to the content of this article.

[[[ p. 18 ]]]

[Summary: This page provides a list of references used in the study. These references cover a range of topics related to flyrock prediction, blasting techniques, and the application of machine learning in mining and geotechnical engineering. The references include journal articles and conference papers from various sources.]

Sustainability 2023 , 15 , 8424 18 of 20 References 1 Raina, A.K.; Chakraborty, A.K.; Choudhury, P.B.; Sinha, A. Flyrock danger zone demarcation in opencast mines: A risk based approach Bull. Eng. Geol. Environ 2011 , 70 , 163–172. [ CrossRef ] 2 Stojadinovic, S.; Pantovic, R.; Zikic, M. Prediction of flyrock trajectories for forensic applications using ballistic flight equations Int. J. Rock Mech. Min. Sci 2011 , 48 , 1086–1094. [ CrossRef ] 3 Rad, H.N.; Hasanipanah, M.; Rezaei, M.; Eghlim, A.L. Developing a least squares support vector machine for estimating the blast-induced flyrock Eng. Comput 2018 , 34 , 709–717. [ CrossRef ] 4 Jamei, M.; Hasanipanah, M.; Karbasi, M.; Ahmadianfar, I.; Taherifar, S. Prediction of flyrock induced by mine blasting using a novel kernel-based extreme learning machine J. Rock Mech. Geotech. Eng 2021 , 13 , 1438–1451. [ CrossRef ] 5 Yari, M.; Armaghani, D.J.; Maraveas, C.; Ejlali, A.N.; Mohamad, E.T.; Asteris, P.G. Several Tree-Based Solutions for Predicting Flyrock Distance Due to Mine Blasting Appl. Sci 2023 , 13 , 1345. [ CrossRef ] 6 Raina, A.K.; Chakraborty, A.K.; More, R.; Choudhury, P.B. Design of factor of safety based criterion for control of flyrock/throw and optimum fragmentation J. Inst. Eng. Ser. A 2007 , 87 , 13–17 7 Ghasemi, E.; Sari, M.; Ataei, M. Development of an empirical model for predicting the effects of controllable blasting parameters on flyrock distance in surface mines Int. J. Rock Mech. Min. Sci 2012 , 52 , 163–170. [ CrossRef ] 8 Armaghani, D.J.; Mahdiyar, A.; Hasanipanah, M.; Shirani Faradonbeh, R.; Khandelwal, M.; Bakhshandeh Amnieh, H. Risk assessment and prediction of flyrock distance by combined multiple regression analysis and monte-carlo simulation of quarry blasting Rock Mech. Rock Eng 2016 , 49 , 3631–3641. [ CrossRef ] 9 Hasanipanah, M.; Jahed Armaghani, D.; Bakhshandeh Amnieh, H.; Abd Majid, M.Z.; Tahir, M. 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[Summary: This page continues the list of references used in the study. These references cover a range of topics related to flyrock prediction, blasting techniques, and the application of machine learning in mining and geotechnical engineering. The references include journal articles and conference papers from various sources.]

Sustainability 2023 , 15 , 8424 19 of 20 29 Hasanipanah, M.; Bakhshandeh Amnieh, H. A fuzzy rule based approach to address uncertainty in risk assessment and prediction of blast-induced flyrock in a quarry Nat. Resour. Res 2020 , 29 , 669–689. [ CrossRef ] 30 Huat, C.Y.; Moosavi, S.M.H.; Mohammed, A.S.; Armaghani, D.J.; Ulrikh, D.V.; Monjezi, M.; Hin Lai, S. Factors Influencing Pile Friction Bearing Capacity: Proposing a Novel Procedure Based on Gradient Boosted Tree Technique Sustainability 2021 , 13 , 11862 [ CrossRef ] 31 Hosseini, S.; Pourmirzaee, R.; Armaghani, D.J.; Sabri Sabri, M.M. Prediction of ground vibration due to mine blasting in a surface lead–zinc mine using machine learning ensemble techniques Sci. Rep 2023 , 13 , 6591. [ CrossRef ] [ PubMed ] 32 Monjezi, M.; Mehrdanesh, A.; Malek, A.; Khandelwal, M. Evaluation of effect of blast design parameters on flyrock using artificial neural networks Neural Comput. Appl 2013 , 23 , 349–356. [ CrossRef ] 33 Ghasemi, E.; Amini, H.; Ataei, M.; Khalokakaei, R. Application of artificial intelligence techniques for predicting the flyrock distance caused by blasting operation Arab. J. Geosci 2014 , 7 , 193–202. [ CrossRef ] 34 Trivedi, R.; Singh, T.N.; Gupta, N. Prediction of blast-induced flyrock in opencast mines using ANN and ANFIS Geotech. Geol Eng 2015 , 33 , 875–891. [ CrossRef ] 35 Faradonbeh, R.S.; Armaghani, D.J.; Monjezi, M. Development of a new model for predicting flyrock distance in quarry blasting: A genetic programming technique Bull. Eng. Geol. Environ 2016 , 75 , 993–1006. [ CrossRef ] 36 Ye, J.; Koopialipoor, M.; Zhou, J.; Jahed Armaghani, D.; He, X. A Novel Combination of Tree-Based Modeling and Monte Carlo Simulation for Assessing Risk Levels of Flyrock Induced by Mine Blasting Nat. Resour. Res 2021 , 30 , 225–243. [ CrossRef ] 37 Hemmati Sarapardeh, A.; Larestani, A.; Nait Amar, M.; Hajirezaie, S Applications of Artificial Intelligence Techniques in the Petroleum Industry ; Gulf Professional Publishing: Houston, TX, USA, 2020. [ CrossRef ] 38 Cai, M.; Hocine, O.; Salih Mohammed, A.; Chen, X.; Nait Amar, M.; Hasanipanah, M. Integrating the LSSVM and RBFNN models with three optimization algorithms to predict the soil liquefaction potential Eng. Comput 2021 , 38 , 3611–3623. [ CrossRef ] 39 Suykens, J.A.K.; Vandewalle, J. Least squares support vector machine classifiers Neural Process. Lett 1999 , 9 , 293–300. [ CrossRef ] 40 Forrester, A.I.J.; S ó bester, A.; Keane, A.J Engineering Design via Surrogate Modelling: A Practical Guide ; John Wiley & Sons: Hoboken, NJ, USA, 2008 41 Rashedi, E.; Nezamabadi-Pour, H.; Saryazdi, S. GSA: A gravitational search algorithm Inf. Sci 2009 , 179 , 2232–2248. [ CrossRef ] 42 Mirjalili, S.; Lewis, A. The Whale Optimization Algorithm Adv. Eng. Softw 2016 , 95 , 51–67. [ CrossRef ] 43 Karaboga, D An Idea Based on Honey Bee Swarm for Numerical Optimization ; Technical Report-TR 06; Erciyes University, Engineering Faculty, Computer Engineering Department: Kayseri, Turkey, 2005 44 Karaboga, D.; Basturk, B. A powerful and efficient algorithm for numerical function optimization: Artificial bee colony (ABC) algorithm J. Glob. Optim 2007 , 39 , 459–471. [ CrossRef ] 45 Nait Amar, M. Modelling solubility of sulfur in pure hydrogen sulfide and sour gas mixtures using rigorous machine learning methods Int. J. Hydrogen Energy 2020 , 45 , 33274–33287. [ CrossRef ] 46 Abujazar, M.S.S.; Fatihah, S.; Ibrahim, I.A.; Kabeel, A.E.; Sharil, S. Productivity modelling of a developed inclined stepped solar still system based on actual performance and using a cascaded forward neural network model J. Clean. Prod 2018 , 170 , 147–159 [ CrossRef ] 47 Hemmati-Sarapardeh, A.; Varamesh, A.; Husein, M.M.; Karan, K. 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The use of GA and PSO in evaluating the shear strength of steel fiber reinforced concrete beams KSCE J. Civ. Eng 2022 , 26 , 3918–3931. [ CrossRef ] 52 Huang, J.; Xue, J. Optimization of SVR functions for flyrock evaluation in mine blasting operations Environ. Earth Sci 2022 , 81 , 434. [ CrossRef ] 53 Talebkeikhah, M.; Amar, M.N.; Naseri, A.; Humand, M.; Hemmati-Sarapardeh, A.; Dabir, B.; Seghier, M.E.A.B. Experimental measurement and compositional modeling of crude oil viscosity at reservoir conditions J. Taiwan Inst. Chem. Eng 2020 , 109 , 35–50. [ CrossRef ] 54 Rostami, A.; Baghban, A.; Shirazian, S. On the evaluation of density of ionic liquids: Towards a comparative study Chem. Eng Res. Des 2019 , 147 , 648–663. [ CrossRef ] 55 Koopialipoor, M.; Fallah, A.; Armaghani, D.J.; Azizi, A.; Mohamad, E.T. Three hybrid intelligent models in estimating flyrock distance resulting from blasting Eng. Comput 2019 , 35 , 243–256. [ CrossRef ] 56 Faradonbeh, R.S.; Armaghani, D.J.; Amnieh, H.B.; Mohamad, E.T. Prediction and minimization of blast-induced flyrock using gene expression programming and firefly algorithm Neural Comput. Appl 2018 , 29 , 269–281. [ CrossRef ] 57 Zhou, J.; Aghili, N.; Ghaleini, E.N.; Bui, D.T.; Tahir, M.M.; Koopialipoor, M. A Monte Carlo simulation approach for effective assessment of flyrock based on intelligent system of neural network Eng. Comput 2019 , 36 , 713–723. [ CrossRef ]

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[Summary: This page concludes the list of references and includes a disclaimer from the publisher regarding the content of the publications. It states that the opinions and data are solely those of the authors and not of MDPI or the editors. MDPI and the editors disclaim responsibility for any injury resulting from the content.]

Sustainability 2023 , 15 , 8424 20 of 20 58 Nguyen, H.; Bui, X.-N.; Nguyen-Thoi, T.; Ragam, P.; Moayedi, H. Toward a state-of-the-art of fly-rock prediction technology in open-pit mines using EANNs model Appl. Sci 2019 , 9 , 4554. [ CrossRef ] 59 Marto, A.; Hajihassani, M.; Jahed Armaghani, D.; Tonnizam Mohamad, E.; Makhtar, A.M. A novel approach for blast-induced flyrock prediction based on imperialist competitive algorithm and artificial neural network Sci. World J 2014 , 2014 , 643715 [ CrossRef ] Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

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