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The balancing of the disassembly line directly affects the productivity of the disassembly process. The disassembly line balancing (DLB) problem can be determined as assigning the tasks to serial workstations to optimize some performance measures like number of workstations, cycle time, removing hazardous parts earlier, etc. The aim of the paper is to develop an efficient heuristic algorithm to minimize the number of workstations under a pre-known cycle time. In this paper, a genetic algorithm (GA) and a constructive heuristic based on the Dijkstra algorithm is proposed to solve the DLB problem with stochastic task times that is caused by the nature of disassembly operation. The proposed algorithms are tested on benchmark problems and compared with the results of the piecewise-linear model (PLM) and simulated annealing (SA). The average relative percentage deviation is applied to transfer the obtained number of workstations. The results obtained by GA are clearly superior in all tests problem according to average relative percentage deviation. Moreover, the proposed constructive heuristic based on the Dijkstra algorithm is also superior to PLM and SA algorithm with respect to number of workstations and the computational times. The proposed approaches can be a very competitive and promising tool for further research in DLB literature and real cases in industries according to test results. Disassembly lines which need less time or number of workstations for balancing may be simply designed by the proposed techniques. [ABSTRACT FROM AUTHOR]

Geomagnetism, similar to other areas of geophysics, is an observation-based science. Data agreement between comparative geomagnetic vector observations is one of the most important evaluation criteria for high-quality geomagnetic data. The main influencing factors affecting the agreement between comparative observational data are the attitude angle, scale factor, long-term time drift, and temperature. In this paper, we propose a method based on a genetic algorithm and linear regression to correct for these effects and use the distribution pattern of points in Bland–Altman plots with a 95% confidence interval length to qualitatively and quantitatively evaluate the agreement between the comparative observational data. In Bland–Altman plots with better agreement, that is, with the corrected data, more than 95% of the points are distributed within the 95% confidence interval and there is no obvious pattern in the distribution of the points. Meanwhile, the length of 95% confidence interval decreased significantly after the correction. The method presented here has positive effects on the vector instrumentation detection and would enhance the robustness of geomagnetic observatory by bringing the data quality of the backup variometer data in line with the primary variometer. [ABSTRACT FROM AUTHOR]

This paper addresses the unrelated parallel machine scheduling problem with sequence and machine dependent setup times and machine eligibility constraints. The objective is to minimize the maximum completion time (makespan). Instances of more than 500 jobs and 50 machines are not uncommon in industry. Such large instances become increasingly challenging to provide high-quality solutions within limited amount of computational time, but so far, have not been adequately addressed in recent literature. A hybrid genetic algorithm is developed, which is lean in the sense that is equipped with a minimal number of parameters and operators, and which is enhanced with an effective local search operator, specifically targeted to solve large instances. For evaluation purposes a new set of larger problems is generated, consisting of up to 800 jobs and 60 machines. An extensive comparative study shows that the proposed method performs significantly better compared to other state-of-the-art algorithms, especially for the new larger instances. Also, it is demonstrated that calibration is crucial and in practice it should be targeted at a narrower set of representative instances. [ABSTRACT FROM AUTHOR]

With the growth in ad hoc devices, mobile ad hoc networks (MANETs) are extensively employed to realize different kinds of real-time applications. However, ad hoc devices suffer from numerous kinds of security attacks such as blackhole, grayhole, wormhole, etc. Therefore, an efficient trust management protocol is preferable. In this paper, a novel gradient boost classifier is proposed. Additionally, the hyper-parameters of gradient boost classifier are tuned using θ -non-dominated sorting genetic algorithm-III (θ NSGA-III). Optimized link state routing (OLSR) protocol is employed for experimental analysis. A multi-class dataset is collected by implementing the blackhole, grayhole, and wormhole attacks on the OLSR. Comparative analysis reveals that the proposed θ NSGA-III-based gradient boost classifier outperforms the competitive attack classification models. [ABSTRACT FROM AUTHOR]

This paper develops a new mathematical model and proposes two meta-heuristics for solving a two-machine flowshop scheduling problem that minimizes bi-objectives, namely the total idle time and the mean deviation from a common due data. In this paper, we assume the arrival time of jobs is dynamic, in which each job has a time window and can arrive in its time window randomly. We also assume the learning effect on the processing times considering as a position-dependent effect. Since the problem is an NP-hard one, we present a multiobjective genetic algorithm (MOGA) and a multiobjective simulated annealing (MOSA) algorithm to solve the given problems. The computational results confirm that the proposed MOGA has a better solution in comparison with the proposed MOSA, especially in large-sized problems. [ABSTRACT FROM AUTHOR]

No-wait job shop scheduling problems refer to the set of problems in which a number of jobs are available for processing on a number of machines in a job shop context with the added constraint that there should be no waiting time between consecutive operations of the jobs. In this paper, a two-machine, no-wait job shop problem with separable setup times and a single-server constraint is considered. The considered performance measure is the makespan. This problem is strongly NP-hard. A mathematical model of the problem is developed and a number of propositions are proven for the special cases. Moreover, a genetic algorithm is proposed in this paper to find the optimal (or near-optimal) solutions. In order to evaluate the developed algorithm, a number of small instances are solved to optimality using the developed mathematical model. The proposed algorithm is able to find the optimal solution of all of these cases. For larger instances, the developed algorithm has been compared with the 2-opt algorithm as well as a proposed lower bound. Computational results show the efficiency of the proposed algorithm in generating good quality solutions compared to the developed lower bounds and 2-opt algorithm. [ABSTRACT FROM AUTHOR]

This paper considers the problem of no-wait flow shop scheduling, in which a number of jobs are available for processing on a number of machines in a flow shop context with the added constraint that there should be no waiting time between consecutive operations of a job. Each operation has a separable setup time, meaning that the setup time of an operation is independent on the previous operations; and the machine can be prepared for a specific operation and remain idle before the operation actually starts. The considered objective function in this paper is the makespan. The problem is proven to be NP-hard. In this paper, two frameworks based on genetic algorithm and particle swarm optimization are developed to deal with the problem. For the case of no-wait flow shop problem without setup times, the developed algorithms are applied to a large number of benchmark problems from the literature. Computational results confirm that the proposed algorithms outperform other methods by improving many of the best-known solutions for the test problems. For the problems with setup time, the algorithms are compared against the famous 2-Opt algorithm. Such comparison reveals the efficiency of the proposed method in solving the problem when separable setup times are considered. [ABSTRACT FROM AUTHOR]

Magnetic field synthesis problems have been discussed at length in scientific literature but they still remain as a topic of research in electrical engineering, physics and medical applications. In these disciplines, there is often a need to design an electromagnetic arrangement which can generate a magnetic field of required distribution. Such an arrangement can also work as an active shield. The aim of an active shield is to generate a specified magnetic field which counteracts the external magnetic fields in a protected region. The idea of active shielding is to construct a suitable arrangement of coils, excited with currents that generate an opposite magnetic field sufficient to cancel out the unwanted external fields. The opposite field must have the same frequency and amplitude as the external field. If the incident field presents a wide bandwidth, the final aim is to generate an opposite field in the same frequency range or at least in a range as large as possible. Two independent methods of magnetic fields synthesis, i.e. iteratively regularized Gauss-Newton method and Genetic Algorithm coupled with Bezier curves-based method, are discussed and compared in this paper. [ABSTRACT FROM AUTHOR]

This paper compares the performance of three population-based algorithms including particle swarm optimization (PSO), evolutionary programming (EP), and genetic algorithm (GA) to solve the multi-objective optimal power flow (OPF) problem. The unattractive characteristics of the cost-based OPF including loss, voltage profile, and emission justifies the necessity of multi-objective OPF study. This study presents the programming results of the nine essential single-objective and multi-objective functions of OPF problem. The considered objective functions include cost, active power loss, voltage stability index, and emission. The multi-objective optimizations include cost and active power loss, cost and voltage stability index, active power loss and voltage stability index, cost and emission, and finally cost, active power loss, and voltage stability index. To solve the multi-objective OPF problem, Pareto optimal method is used to form the Pareto optimal set. A fuzzy decision-based mechanism is applied to select the best comprised solution. In this work, to decrease the running time of load flow calculation, a new approach including combined Newton-Raphson and Fast-Decouple is conducted. The proposed methods are tested on IEEE 30-bus test system and the best method for each objective is determined based on the total cost and the convergence values of the considered objectives. The programming results indicate that based on the inter-related nature of the objective functions, a control system cannot be recommended based on individual optimizations and the secondary criteria should also be considered. [ABSTRACT FROM AUTHOR]

Flow-shop scheduling problem (FSP) deals with the scheduling of a set of jobs that visit a set of machines in the same order. The FSP is NP-hard, which means that there is no efficient algorithm to reach the optimal solution of the problem. To minimize the make-span of large permutation flow-shop scheduling problems in which there are sequence-dependent setup times on each machine, this paper develops one novel hybrid genetic algorithms (HGA). Proposed HGA apply a modified approach to generate the population of initial chromosomes and also use an improved heuristic called the iterated swap procedure to improve them. Also the author uses three genetic operators to make good new offspring. The results are compared to some recently developed heuristics and computational experimental results show that the proposed HGA performs very competitively with respect to accuracy and efficiency of the solutions. [ABSTRACT FROM AUTHOR]

The extrusion die plays a crucial role in aluminum alloy profile production, which influences product quality and service life of extrusion die directly. In this paper, a profile with irregular shape was taken as an analysis example, and multiobjective optimization for porthole extrusion die based on modern intelligence algorithm was carried out. Aiming at achieving the uniform velocity distribution in the cross-section of the profile as well as decreasing the maximum stress on the extrusion die and the deflection of the mandrel, the angle between port bridges, the position of die orifice, and the height of welding chamber were considered as the design variables. Then Kriging model was established on the basis of Latin hypercube samplings, and above design variables were optimized using Pareto-based genetic algorithm. Finally, an optimal die structure is gained. Compared with the initial scheme, the velocity distribution in the extrudate was more even, and the stress on the die and the deflection of the mandrel were decreased obviously in the optimal scheme. The optimal design method for porthole die has strong commonality, thus, it could give useful guidelines for practical production of the same kind of aluminum profile. [ABSTRACT FROM AUTHOR]

This paper addresses the management of a sugarcane harvest over a multi-year planning period. A methodology to assist the harvest planning of the sugarcane is proposed in order to improve the production of POL (a measure of the amount of sucrose contained in a sugar solution) and the quality of the raw material, considering the constraints imposed by the mill such as the demand per period. An extended goal programming model is proposed for optimizing the harvest plan of the sugarcane so the harvesting point is as close as possible to the ideal, considering the constrained nature of the problem. A genetic algorithm (GA) is developed to tackle the problem in order to solve realistically large problems within an appropriate computational time. A comparative analysis between the GA and an exact method for small instances is also given in order to validate the performance of the developed model and methods. Computational results for medium and large farm instances using GA are also presented in order to demonstrate the capability of the developed method. The computational results illustrate the trade-off between satisfying the conflicting goals of harvesting as closely as possible to the ideal and making optimum use of harvesting equipment with a minimum of movement between farms. They also demonstrate that, whilst harvesting plans for small scale farms can be generated by the exact method, a meta-heuristic GA method is currently required in order to devise plans for medium and large farms. [ABSTRACT FROM AUTHOR]

This paper presents a novel hybrid optimization approach based on teaching-learning based optimization (TLBO) algorithm and Taguchi's method. The purpose of the present research is to develop a new optimization approach to solve optimization problems in the manufacturing area. This research is the first application of the TLBO to the optimization of turning operations in the literature The proposed hybrid approach is applied to two case studies for multi-pass turning operations to show its effectiveness in machining operations. The results obtained by the proposed approach for the case studies are compared with those of particle swarm optimization algorithm, hybrid genetic algorithm, scatter search algorithm, genetic algorithm and integration of simulated annealing, and Hooke-Jeeves patter search. [ABSTRACT FROM AUTHOR]

Many software engineering problems have been addressed with search algorithms. Search algorithms usually depend on several parameters (e.g., population size and crossover rate in genetic algorithms), and the choice of these parameters can have an impact on the performance of the algorithm. It has been formally proven in the No Free Lunch theorem that it is impossible to tune a search algorithm such that it will have optimal settings for all possible problems. So, how to properly set the parameters of a search algorithm for a given software engineering problem? In this paper, we carry out the largest empirical analysis so far on parameter tuning in search-based software engineering. More than one million experiments were carried out and statistically analyzed in the context of test data generation for object-oriented software using the EvoSuite tool. Results show that tuning does indeed have impact on the performance of a search algorithm. But, at least in the context of test data generation, it does not seem easy to find good settings that significantly outperform the 'default' values suggested in the literature. This has very practical value for both researchers (e.g., when different techniques are compared) and practitioners. Using 'default' values is a reasonable and justified choice, whereas parameter tuning is a long and expensive process that might or might not pay off in the end. [ABSTRACT FROM AUTHOR]

This paper presents a memetic algorithm (MA) to minimize the total weighted number of late jobs (or deliveries) on a single machine. The proposed MA combines a genetic algorithm (GA) with a neighborhood search. The performance of the proposed algorithm is compared with four heuristics from the literature, namely the early due date (EDD), the weighted shortest processing time (WSPT), the forward algorithm (FA), and the weighted forward algorithm (WFA), against 10 benchmark problems and three real-world problems. The results suggest that the MA outperformed the EDD, WSPT, FA, and WFA on the benchmark problems and performed as good as WFA on two of the three real-world problems and outperformed WFA on one real-world problem. The EDD performed the worst among the five solution approaches. [ABSTRACT FROM AUTHOR]

The primary aim of the paper is to compare the different nongradient methods of multiobjective optimization for optimizing the geometry parameters of a cylindrical fin heat sink. The methods studied for comparison are Taguchi-based grey relational analysis, ε (epsilon) constraint method and genetic algorithm. The various responses that have been studied are electromagnetic emitted radiations, thermal resistance and mass of the heat sink. Since the responses are obtained using complex simulation softwares (HFSS-Ansoft for emitted radiations and CFD-Flotherm for thermal resistance), there is no way of calculating the derivates of the objective functions. Hence, the Taguchi design of experiments design is used to derive the linear regression equations for the responses studied, which are then taken as the objective functions to be optimized. A new hybrid method known as Taguchi-based epsilon constraint method has been proposed in this paper for obtaining nondominated Pareto solution set. The results obtained using the proposed method show that the Pareto optimal set is competitive in terms of diversity of the solutions obtained. It is not likely that there exists a solution, which simultaneously minimizes all the objectives using any of the multiobjective techniques implemented. The value path analysis has been done to compare the trade-off among the design alternatives for the chosen multiple objective parameter optimization problem. [ABSTRACT FROM AUTHOR]

A hybrid clustering method is proposed in this paper based on artificial immune system and simulated annealing. An integration of simulated annealing and immunity-based algorithm, combining the merits of both these approaches, is used for developing an efficient clustering method. Tuning the parameters of method is investigated using Taguchi method in order to select the optimum levels of parameters. Proposed method is implemented and tested on three real datasets. In addition, its performance is compared with other well-known meta-heuristics methods, such as ant colony optimization, genetic algorithm, simulated annealing, Tabu search, honey-bee mating optimization, and artificial immune system. Computational simulations show very encouraging results in terms of the quality of solution found, the average number of function evaluations and the processing time required, comparing with mentioned methods. [ABSTRACT FROM AUTHOR]

In this paper we consider a multi-objective group scheduling problem in hybrid flexible flowshop with sequence-dependent setup times by minimizing total weighted tardiness and maximum completion time simultaneously. Whereas these kinds of problems are NP-hard, thus we proposed a multi-population genetic algorithm (MPGA) to search Pareto optimal solution for it. This algorithm comprises two stages. First stage applies combined objective of mentioned objectives and second stage uses previous stage's results as an initial solution. In the second stage sub-population will be generated by re-arrangement of solutions of first stage. To evaluate performance of the proposed MPGA, it is compared with two distinguished benchmarks, multi-objective genetic algorithm (MOGA) and non-dominated sorting genetic algorithm II (NSGA-II), in three sizes of test problems: small, medium and large. The computational results show that this algorithm performs better than them. [ABSTRACT FROM AUTHOR]

In this paper, we present a combination of particle swarm optimization (PSO) and genetic operators for a multi-objective job shop scheduling problem that minimizes the mean weighted completion time and the sum of the weighted tardiness/earliness costs, simultaneously. At first, we propose a new integer linear programming for the given problem. Then, we redefine and modify PSO by introducing genetic operators, such as crossover and mutation operators, to update particles and improve particles by variable neighborhood search. Furthermore, we consider sequence-dependent setup times. We then design a Pareto archive PSO, where the global best position selection is combined with the crowding measure-based archive updating method. To prove the efficiency of our proposed PSO, a number of test problems are solved. Its reliability based on some comparison metrics is compared with a prominent multi-objective genetic algorithm (MOGA), namely non-dominated sorting genetic algorithm II (NSGA-II). The computational results show that the proposed PSO outperforms the above MOGA, especially for large-sized problems. [ABSTRACT FROM AUTHOR]

The paper describes a comparative study of multiple-objective metaheuristics on the bi-objective set covering problem. Ten representative methods based on genetic algorithms, multiple start local search, hybrid genetic algorithms and simulated annealing are evaluated in the computational experiment. Nine of the methods are well known from the literature. The paper introduces also a new hybrid genetic algorithm called Pareto memetic algorithm. The results of the experiment indicate very good performance of hybrid genetic algorithms, however, no algorithm was able to outperform all other methods on all instances. Furthermore, the results indicate that the performance of multiple-objective metaheuristics may differ radically even if the methods are based on the same single objective algorithm and use exactly the same problem-specific operators. [ABSTRACT FROM AUTHOR]

Algorithm-related problems including more than one convergent solutions, endless loop, no solution within the recommended search ranges, low prediction precision, and low efficiency arise when the Oxley's theoretical model and its extended models are applied. A new parameter-based algorithm is proposed in this paper which turns the model-solution-seeking process into an issue of multivariable optimization in order to solve the extended Oxley's theoretical model with higher prediction precision and efficiency. Genetic optimization algorithms and multivariable constrained optimization are combined with other functions offered by Matlab which are used to solve univariate transcendental equations to determine satisfactory model parameters ( C, ϕ, δ), and the global optimal solution is selected as the only solution of the extended Oxley's theoretical model after a comparison of the predicted cutting forces, thrust forces, and chip thicknesses with experimental data. A method to calculate the temperature of the shear plane ( T) is introduced into the extended Oxley's theoretical model to further improve the prediction precision. With the above algorithm and improvements, the predicted results turn out to be in better agreement with the experimental data than the original results of the extended Oxley's theoretical model. [ABSTRACT FROM AUTHOR]

This paper focuses on the scheduling problem of the reconfiguration manufacturing system (RMS) for execution level, where the final objective is to output a production plan. The practical situation in Chinese factory is analyzed, and the characteristics are summarized into the contradiction between flow and job shop production. In order to handle this problem, a new production planning algorithm in virtual cells is proposed for RMS using an improved genetic algorithm. The advantages of this algorithm have three parts: (1) the virtual cell reconfiguration is formed to assist making production plans through providing relationship among task families and machines from cell formation; (2) The operation buffer algorithm is developed for flow style production in cells, which can realize the nonstop processing for flow style jobs; and (3) The multicell sharing method is proposed to schedule job shop jobs in order to fully utilize manufacturing capability among machines in multicells. Based on the above advantages, an improved genetic algorithm is developed to output scheduling plan. At last, the algorithm is tested in different instances with LINGO and the other genetic algorithm, and then the scheduling solution comparison shows the proposed algorithm can get a better optimum result with the same time using the comparison algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we study single-machine scheduling problem when each job is considered with linear earliness and quadratic tardiness penalties with no machine idle time. Here the objective is to find the best sequence of jobs in the reasonable time. This model was studied in several researches, and some algorithms were proposed to solve it such as genetic algorithm. As the size of problem increased, such algorithms were not effective and efficient. Hence, we proposed the hybrid imperialist competitive algorithm. The proposed algorithm is based upon the imperialist competitive algorithm and genetic algorithm concepts. This algorithm was tested in problems with different sizes. The results denoted that the hybrid algorithm can solve different size of problem in reasonable time. This procedure showed its efficiency in medium- and large-sized problems as compared with other available methods. [ABSTRACT FROM AUTHOR]

One fundamental problem in cellular manufacturing is the formation of product families and machine cells. Many solution methods have been developed for the cell formation problem. Since efficient grouping is the prerequisite of a successful Cellular Manufacturing installation the research in this area will likely be continued. In this paper, we consider the problem of cell formation in cellular manufacturing systems with the objective of maximizing the grouping efficacy. We propose a Genetic Algorithm (GA) to obtain machine-cells and part-families. Developed GA has three different selection and crossover operators. The proper operators and parameters of the GA were determined by design of experiments. A set of 15 test problems with various sizes drawn from the literature is used to test the performance of the proposed algorithm. The corresponding results are compared to several well-known algorithms published. The comparative study shows that the proposed GA improves the grouping efficacy for 40% of the test problems. [ABSTRACT FROM AUTHOR]

Regression analysis is one of the most applicable methods in statistical methodology used to find the best regression model according to the relationship among several variables in a system. The estimation of regression model, which is solved as a formulate optimization problem and making use of heuristic algorithms, is much simpler and faster than classic methods. Genetic algorithm (GA) as one of the heuristic algorithms had been used to solve this problem. In this paper, we extend the noising method as a recent combinatorial optimization problem to estimate the best regression model and evaluate its performances compared to GA. Also, in order to enhance the performance of our GA, we apply the Taguchi experimental design method to tune the parameters of the algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a generic optimisation methodology for the selection of optimal process parameters in multiresponse processes that consists of two stages: The first stage is based on a quality loss function and multivariate statistical methods in order to adequately present responses, uncorrelate and synthesise them into a single process performance measure; the second stage uses artificial neural networks to build a process model and a simulated annealing (SA) algorithm to find the optimal process parameter conditions. The initial point of the SA algorithm is generated in such a way as to improve the convergence to the actual global optimum. The most important SA algorithm parameters are varied to assess the algorithm's robustness in terms of the effect of the algorithm setting on the quality of the final solution (optimal process parameters and the corresponding process performance measure). The results are benchmarked to genetic algorithm (GA) performance within the proposed methodology, and the quality of a final solution, the robustness of the optimisation algorithm, the speed of a convergence to the optimum and the computational time are evaluated. Four case studies are presented to illustrate the effectiveness of the proposed methodology in comparison to several commonly used approaches from the literature and also to the GA-based performance. [ABSTRACT FROM AUTHOR]

Abstract  This paper discusses a closed-loop centralized control for a multi-input multi-output active magnetic bearing system. A genetic algorithm for design and a credible comparison of different controller structures are proposed. The evaluation of the design trade-offs of linear-quadratic and loop transfer recovery controllers are studied. The model-based controllers are compared with the classical PID controller and the cascaded PI/PD controller. The properties of the tested control configurations are examined using maximum singular values of the output sensitivity function of the closed-loop system and the tolerated disturbance at the input of the plant. Furthermore, indices such as measured peak output sensitivity, singular values of the uncertain control system, responses to the step reference position, step disturbance, and impulse force disturbance are examined. A good agreement between the simulation and the experimental results from the test-rig is shown. [ABSTRACT FROM AUTHOR]

One of important subjects for business and financial institutions in recent decades is bankruptcy prediction. In this study, we predict bankruptcy using both logit and genetic algorithm (GA) prediction techniques under sanctions circumstances. This study also compares the performance of bankruptcy prediction models by identifying conditions under which a model performs better to examine the relative performance of models, GA was used to classify 174 bankrupt and non-bankrupt Iranian firms listed in Tehran stock exchange for the period 2006–2014. Genetic model achieved 95 and 93.5 % accuracy rates in training and test samples, respectively; while logit model achieved only 77 and 75 % accuracy rates in training and test samples, respectively. The results suggest that two models have the capability of predicting bankruptcy and GA model is more accurate than the logit model in this regard. [ABSTRACT FROM AUTHOR]

Traditional approaches to the study of technical analysis (TA) often focus on the performance of a single indicator, which seems to fall short in scope and depth. We use a genetic algorithm (GA) to optimize trading strategies in the three major Forex markets in order to ascertain the suitability of TA strategies and rules to achieve consistently superior returns, by comparing momentum, trend and breakout indicators. The indicators with the parameters generated through our GA consistently outperform the equivalent indicators by applying parameters commonly used by the trading industry. EUR/USD and GBP/USD markets have interesting return figures before trading costs. The inclusion of spreads and commissions weakens returns substantially, suggesting that under a more realistic set of assumptions these markets could be efficient. Trend indicators generate better outcomes and GBP/USD qualifies as the most profitable market. Different aggregate returns in different markets may be evidence of distinct maturation stages under an evolving efficiency market perspective. Our GA is able to search a wider solution space than traditional configurations and offers the possibility of recovering latent data, thus avoiding premature convergence. [ABSTRACT FROM AUTHOR]

Background: In this study, bio-inspired computing is exploited for solving system of nonlinear equations using variants of genetic algorithms (GAs) as a tool for global search method hybrid with sequential quadratic programming (SQP) for efficient local search. The fitness function is constructed by defining the error function for systems of nonlinear equations in mean square sense. The design parameters of mathematical models are trained by exploiting the competency of GAs and refinement are carried out by viable SQP algorithm. Results: Twelve versions of the memetic approach GA-SQP are designed by taking a different set of reproduction routines in the optimization process. Performance of proposed variants is evaluated on six numerical problems comprising of system of nonlinear equations arising in the interval arithmetic benchmark model, kinematics, neurophysiology, combustion and chemical equilibrium. Comparative studies of the proposed results in terms of accuracy, convergence and complexity are performed with the help of statistical performance indices to establish the worth of the schemes. Conclusions: Accuracy and convergence of the memetic computing GA-SQP is found better in each case of the simulation study and effectiveness of the scheme is further established through results of statistics based on different performance indices for accuracy and complexity. [ABSTRACT FROM AUTHOR]

Mean flow stress of microalloyed high-strength steels during plate rolling has been thoroughly studied. It has been found out by both thermomechanical tests and measurements taken in the industrial plate mill. For this purpose, log data obtained from the plate rolling mills have been converted to mean flow stress using the Sims approach. The agreement between thermomechanical tests and mill data has been tested in order to confirm that thermomechanical testing can provide an easy, convenient and very effective simulation of industrial hot rolling process. The results are analysed and compared to the predictions of some mathematical models developed in literature. Subsequently, the best performing formula, namely the Poliak's equation, has been optimised by means of genetic algorithms and the standard Gauss-Newton method. This latter has allowed a finer tuning of the models' parameters in order to fit at best the available data. The Poliak's formula optimised by genetic algorithms is shown to accurately predict the mean flow stress and therefore it provides a useful tool for the determination of the milling settings before the incoming strip enters the mill. [ABSTRACT FROM AUTHOR]

In this study, a facility layout problem having NP-hard problem characteristic is attempted to be solved by using two different meta-heuristic approaches-Genetic Algorithm (GA) and Simulated Annealing (SA)-and a hybrid approach-Genetic Algorithm/Simulated Annealing (HGASA). The case study is completed for a company which can be seen as a small or a medium size enterprise. First, parameter values of GA and SA are determined by testing for various combinations of them. Then, the algorithms are run for one hundred times. The results of the algorithms are compared based on their fitness values and calculation time requirements using the paired-t test, mean and standard values. The results show that SA performs better than the others in terms of the fitness values and the time requirements. In this study, we also test the performance of our GA, SA and HGASA methodologies using some of the well-known test problems from the literature. We obtain very close results to those in literature. [ABSTRACT FROM AUTHOR]

In the multi-pass rod rolling systems, where the final products are round bars with different sizes, oval-edging oval passes are widely employed as intermediate passes. This study attempts to present a generalized strategy to support the optimal design of oval-edging oval passes. A design system based on this strategy is developed to minimize power consumption, to reduce trials and errors in industry, as well as to improve the design efficiency and flexibility. A series of equations are established for geometrical modeling and graphic plotting of oval-edging oval passes, which can realize the parametric transformation for roll pass design and optimization. A novel formula based on statistical analysis and data fitting is proposed for the calculation of power consumption. To verify this formula, results obtained are compared with those calculated from using the Smirnov's formula. The comparison confirmed the accuracy and efficiency of this formula. Finally, the proposed approach is applied for the optimal design of oval-edging oval passes, which are widely employed for the intermediate passes in the rod rolling systems. Through the comparison between simulation results and experimental data from literature, it is concluded that the proposed method can reduce power consumption of these passes and is able to improve the efficiency and flexibility of intermediate pass design without compromising its accuracy. [ABSTRACT FROM AUTHOR]

Myopic scheduling uses information without correct context. Because job shops with dynamic job arrival are NP-hard, real-world planners often resort to myopic dispatching rules that produce schedules with unsatisfactory makespans and mean flow times. If metaheuristic scheduling does not use context properly, it can produce unsatisfactory schedules. This study proposes a new theory of context-dependent and multi-contextual scheduling functions in dynamic job shops. Three multi-contextual ant colony (MCAC) scheduling methods, SPT_MIT_JWT, MRT_MIT, and LRT_MIT_JWT, were designed to combine several context-dependent functions so that each ant had an independent, artificially intelligent model of what might happen in the future. These three MCACs scheduled 27 dynamic job shops. Each job shop had three parameters (number of operations per job, processing time per operation, and utilization level) at one of three levels. The results were compared to schedules from dispatching rules. Schedules from MRT_MIT had the best makespans for all 27 combinations of factors. For five cases in which utilization and operations per job were both high, schedules from longest processing time had the best mean flow time; in the other 22 cases, either SPT_MIT_JWT or LRT_MIT_JWT produced the schedule with the best mean flow time. These results indicate that the new theory can be used to design multi-contextual methods that produce effective schedules. [ABSTRACT FROM AUTHOR]