Journal of Intelligent & Fuzzy Systems - Volume 37, issue 1

Authors: Jia, Ruru | Bai, Xuejie | Song, Fengxuan | Liu, Yankui

Article Type: Research Article

Abstract: Sustainable development problem involves several conflicting criteria on economy, energy, environment and social aspects and some sources of uncertainty due to its attribute. It is necessary to mitigate risks in sustainable development schedule. However, the existing literature includes limited quantitative research on robust strategies for sustainable development under uncertainty. Under these concerns, this paper presents a robust multi-objective optimization formulation for allocating labor across economic sectors to simultaneously satisfy economy (gross domestic product, GDP), environment (greenhouse gas (GHG) emissions), energy (electricity) and society (labor), in which the per capita GDP, per capita electricity consumption, per capita GHG and per capita …rate of unemployment are robust uncertainty. There are three conflicting objectives in our sustainable development problem. The first objective maximizes the sectoral GDP, the second objective minimizes the sectoral electricity consumption and the third objective minimizes the sectoral GHG emissions. We adapt ɛ -constraint method to deal with the multiple objectives for the sustainable development problem, and obtain a more flexible result via an interactive decision-making process. Since uncertainty has often led to computationally intractable models, we reformulate the proposed model using robust optimization method into the tractable robust counterpart (RC) forms under two types of uncertainty sets. Finally, to demonstrate the effectiveness and applicability for our model, we conduct a case study for meeting year 2030 sustainable development of the United Arab Emirates (UAE). The numerical results show: (a) the robust multi-objective model is effective in uncertain environment and provides a reliable decision tool than deterministic model for integrated multi-objective sustainable development problem; (b) when the possibility distributions of uncertain parameters are available, fuzzy optimization model can provide better decision-making than robust model under box uncertainty set. Show more

Keywords: Sustainable development, multiple objectives, robust optimization, fuzzy optimization

DOI: 10.3233/JIFS-182763

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1311-1326, 2019

Authors: Peng, Xindong

Article Type: Research Article

Abstract:  This paper is designed to show deeper standpoints for dealing the decision making issues based on intuitionistic fuzzy soft set (IFSS). Firstly, we propose a novel definition and formula of similarity measure on intuitionistic fuzzy information, which can reserve more original judgment information. Afterwards, we present a combination weight that take the objective weight (obtained by grey system theory) and the subjective weight into consideration. Later, three intuitionistic fuzzy soft methods based on similarity measure, MABAC and EDAS are presented for dealing the decision making issues. Finally, the validity of methods are stated by some practical examples. The key characteristics …of the developed methods have no strict requirements for decision data and possess a stronger ability in differentiating the best alternative. Show more

Keywords: Similarity measure, combination weights, IFSS, MABAC, EDAS

DOI: 10.3233/JIFS-182768

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1327-1341, 2019

Authors: Dinçer, Hasan | Yüksel, Serhat

Article Type: Research Article

Abstract: The selection of investment strategies is one of prominent issues for the service industries in the competitive market environment. The aim of the study is to evaluate the investment strategies for the European tourism industry using a hybrid decision making approach based on the interval type-2 fuzzy sets. For this purpose, a set of criteria and dimensions for the investments strategies of the European tourism is proposed. Interval type-2 fuzzy DEMATEL is applied to weight the criteria and dimensions and interval type-2 fuzzy MOORA is used for selecting the best investment strategies for the European tourism industry. The novelty of …the study is to propose a set of investment strategies for the European tourism and the extended methods for DEMATEL and MOORA under the fuzzy environment. A novel hybrid approach is also proposed to the decision-making process based on the interval type-2 fuzzy sets. The major results are summarized as European countries should firstly focus on increasing the number of touristic facilities in the coast line to attract the attention of the tourists. Similarly, it can also be beneficial for these countries make more private security investment for the tourists to feel more secured while visiting historical places. Owing to these strategies, it can be possible to develop European tourism industry. Show more

Keywords: Tourism, investment strategies, interval type-2 fuzzy DEMATEL, interval type-2 fuzzy MOORA, industry

DOI: 10.3233/JIFS-182773

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1343-1356, 2019

Authors: Bouaita, Bilal | Moussaoui, Abdelouahab | Bachari, Nour El Islam

Article Type: Research Article

Abstract: The Meteosat Second Generation (MSG) satellite can be used to estimate rainfall through the multispectral images, which are provided every 15 min across 12 channels. However, most studies have not maximized the terabytes of data provided by the channels in this satellite, which are potentially rich in new resources that need to be exploited. Moreover, these studies classify pixels conventionally, where a pixel is considered either 100% precipitant or 0% (no-precipitant), whereas actually it cannot be classified in a clear and unambiguous way. To address this problem, we propose a method that exploits the images of the channels and constructs …an estimation model in the form of fuzzy association rules to estimate the rainfall in Northeastern Algeria. Each rule is in if (condition)-then (conclusion) form, where the condition is a combination of the various fuzzy classes of MSG images, and the conclusion contains a single fuzzy class that represents the intensities of rain: no-rain, low, moderate, and high. The obtained results are compared with the data obtained by the European Organization for the Exploitation of Meteorological Satellites Multisensor Precipitation Estimate program. Show more

Keywords: Data mining, MSG images, apriori algorithm, fuzzy association rules, fuzzy c-means algorithm

DOI: 10.3233/JIFS-182786

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1357-1369, 2019

Authors: Xu, Lan | Li, Peng

Article Type: Research Article

Abstract: Recently, the reform practice of government procurement of public service (GPPS) in China has been promoted gradually and got great breakthrough. Meanwhile, in order to guarantee that the expected goal of this reform achieved, mature and effective regulation is of vital importance. Considering the practical demand, the capability maturity model is applied into the evaluation of quality regulatory capability in GPPS. The concept of quality regulatory capability maturity is proposed, and the evaluation model based on TODIM (an acronym in Portuguese of interactive and multiple attribute decision making) method for probabilistic linguistic term sets (PLTSs) is provided. Taking Jiangsu Province …as an example, an empirical study of its quality regulatory capability evaluation for GPPS is conducted, through which, not only comparative results of maturity levels of different cities in Jiangsu is obtained, but the improving measures are also determined. The proposed maturity evaluation model fully reflects experts’ preferences and evaluation information, and is able to point out the direction for regulatory capability’s future promotion level by level, as well as its continual improvement. Show more

Keywords: Government procurement of public service, quality supervision, capability maturity, evaluation, probabilistic linguistic term set

DOI: 10.3233/JIFS-182788

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1371-1384, 2019

Authors: Sağiroğlu, Yasemin | Gözütok, Uğur

Article Type: Research Article

Abstract:  Metric properties, i.e. properties which are invariant relative to the group E  (3) of all Euclidean motions of the 3-dimensional Euclidean space of fuzzy curves are investigated in this paper. E  (3)-equivalence of fuzzy curves is introduced. E  (3)-equivalence of fuzzy curves is given in terms of fuzzy curvature and fuzzy torsion. All correlations between these fuzzy invariants of a fuzzy curve are described.

Keywords: Fuzzy path, fuzzy curve, invariant

DOI: 10.3233/JIFS-182805

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1385-1397, 2019

Authors: Yue, Xiaofeng | Zhang, Hongbo

Article Type: Research Article

Abstract: As one of the most popular image segmentation techniques, multi-level thresholding is widely used. Much work has been done to improve the efficiency of multi-level thresholding, but satisfied affect is hard to achieve. In this paper, a multi-level image segmentation method using between-class variance (Otsu) based on improved bat algorithm (DWBA) with dynamically adjusting inertia weight and velocity stratification theory is proposed. DWBA algorithm has strong global search ability at the beginning. Then, the local search capability is enhanced with numbers increasing of iterations. More importantly, the performance of DWBA further improved, because bats with different fitness values have diverse …velocities. Furthermore, an improved local search strategy is proposed to avoid the current best solution being replaced during iterations. The experimental results established that the proposed DWBA algorithm obtains better outcome than other algorithms. Show more

Keywords: Multi-level image segmentation, DWBA algorithm, dynamically adjusting inertia weight, velocity stratification theory, Otsu

DOI: 10.3233/JIFS-182806

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1399-1413, 2019

Authors: Zhang, Zi-Xuan | Hao, Wen-Ning | Yu, Xiao-Han | Chen, Jun-Yue | Xu, You-Wei

Article Type: Research Article

Abstract:  Due to the fact that individual knowledge is often inadequate and deficient in group decision-making problems, it is commonly seen that the preference information provided by the decision makers are incomplete. To encounter this problem lots of relevant researches have already been carried out. However, previous methods often only take into account either the information of the expert who provided incomplete preference, or information provided by the rest of the group. To be more thorough and comprehensive, this paper combined both parts of the information, by first setting the unknown preference values as output and known ones as inputs, training …the Bayesian regression model with the complete observations of other experts to detect the associations between them, and then putting in the incomplete preference information to predict the unknown ones. Moreover, inspired by the empirical rule of the Gaussian distribution, this paper also propose to combine the concept of confidence interval with that of interval-valued preference relations, by expressing the prediction results with interval-valued fuzzy reciprocal relations to allow some degree of uncertainty. On the basis of that an iterative consensus reaching process incorporated with feedback mechanism is also proposed. Finally a case study of possible application of our proposed model in project performance evaluations is carried out, the results of which then further verify the practicality and validity of our model. Show more

Keywords: Group decision making, incomplete fuzzy reciprocal preference relation, Bayesian linear regression, consensus reaching process

DOI: 10.3233/JIFS-182817

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1415-1434, 2019

Authors: Safaeian, Mojgan | Fathollahi-Fard, Amir Mohammad | Tian, Guangdong | Li, Zhiwu | Ke, Hua

Article Type: Research Article

Abstract: It is generally believed that the process of supplier selection plays a critical role in the purchasing management. To improve the performance of a supply chain network, it is essential to build a strategic and a strong relationships. As such, all firms should select the best suppliers by applying appropriate methods through different selection criteria. An appropriate supplier reduces all purchasing costs as well as increases customer satisfaction to improve the final product and strengthen corporate competitiveness. Due to the natural uncertainty of this dilemma, most of recent works show a great deal of interest in applying uncertainty approaches. The …main innovation of this paper is to develop a new multi-objective model for both supplier selection and order allocation operations considering incremental discount in a fuzzy environment. The proposed model considers the material cost with incremental discount and the transportation cost, holding costs along with its control and interest as well as the possibility of payment, brought back, and replacement costs, simultaneously, for the first time in this research area. Based on the proposed fuzzy model, the Zimmermann fuzzy approach is used in order to covert the model in a single objective form. Accordingly, a Genetic Algorithm (GA) is applied to solve the proposed problem. Based on the multi-objective optimization proposed, a Non-dominated Sorting GA (NSGA-II) is also employed to solve the developed model through the multi-objective assessment methodologies. Finally, a comprehensive evaluation and discussion based on the results are provided to reveal the performance of developed methodology. Show more

Keywords: Supplier selection, order allocation, incremental discount, zimmermann fuzzy approach, genetic algorithm, NSGA-II

DOI: 10.3233/JIFS-182843

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1435-1455, 2019

Authors: Xun, Xin | Xin, Xiao Long

Article Type: Research Article

Abstract: In this paper, we introduce the notions of node, nodal filter and seminode in equality algebras and study some properties of them. First, we study the relation between nodes and other specific elements. Furthermore, by defining some operations on N F ( E ) , which is the set of all nodal filters in an equality algebra E , we prove that ( N F ( E ) , ∧ , ↔ , E ) is an equality algebra. In fact, we show that N F ( E ) …is a Hertz algebra, BCK-algebra, Hilbert algebra, Kleene algebra and semi-De Morgan algebra. Then we investigate the relation among nodal filters and (positive) implicative, fantastic, prime, and boolean filters in any equality algebras. Finally, we study the relation between nodes and seminodes. And we prove the set of all seminodes SN (E ) is a lattice, Heyting algebra and Hertz algebra under the conditions. Show more

Keywords: Equality algebra, node, nodal filter, seminode, hertz algebra

DOI: 10.3233/JIFS-182860

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1457-1466, 2019

Authors: Fahandezi Sadi, Majid | Ansari, Ebrahim | Afsharchi, Mohsen

Article Type: Research Article

Abstract:  Supervised Word Sense Disambiguation (WSD) systems use features of the target word and its context to learn about all possible samples in an annotated dataset. Recently, word embeddings have emerged as a powerful feature in many NLP tasks. In supervised WSD, word embeddings can be used as a high-quality feature representing the context of an ambiguous word. In this paper, four improvements to existing state-of-the-art WSD methods are proposed. First, we propose a new model for assigning vector coefficients for a more precise context representation. Second, we apply a PCA dimensionality reduction process to find a better transformation of feature …matrices and train a more informative model. Third, a new weighting scheme is suggested to tackle the problem of unbalanced data in standard WSD datasets and finally, a novel idea is presented to combine word embedding features extracted from different independent corpora, which uses a voting aggregator among available trained models. All of these proposals individually improve disambiguation performance on Standard English lexical sample tasks, and using the combination of all proposed ideas makes a significant improvement in the accuracy score. Show more

Keywords: Word sense disambiguation, Word embedding, Supervised learning, Support vector machine

DOI: 10.3233/JIFS-182868

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1467-1476, 2019

Authors: Wang, Guijun | Gao, Jiansi

Article Type: Research Article

Abstract: Simple binary coded genetic algorithm (GA) and particle swarm optimization (PSO) fall easily into local minimums and fail to find the global optimal solution to the algorithm. Thus, the development of a hybrid algorithm between GA and PSO is urgently demanded. In this paper, a three-layer polygonal fuzzy neural network (PFNN) model and its error function are first given by the arithmetic operations of the polygonal fuzzy numbers. Second, the random sequences are constructed by a chaos random generator, these random sequences are used as the initial population of chaos GA and the optimal individuals for sub-populations gained by chaos …search are used as the initial population of PSO, and then an new parallel conjugate gradient-particle swarm optimization (PCG-PSO) is designed. Finally, a case study shows the proposed parallel CG-PS algorithm not only avoids dependence of traditional GA on initial values and overcomes the poor global optimization capability of traditional PSO, but also possesses advantages of rapid convergence and high stability. Show more

Keywords: Polygonal fuzzy number, polygonal fuzzy neural network, chaos genetic algorithm, particle swarm optimization, parallel conjugate gradient-particle swarm optimization

DOI: 10.3233/JIFS-182882

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1477-1489, 2019

Authors: Jani, Kuntesh K. | Srivastava, Subodh | Srivastava, Rajeev

Article Type: Research Article

Abstract: One of the most common lesions of the gastrointestinal tract (GIT) is an ulcer. Capsule endoscopy (CE) is a recent advancement in the field of gastroenterology for diagnosis of GIT abnormalities. However, CE video length ranges from 6 to 8 hours generating approximately 60000 images. For a medical expert, examination of such lengthy videos is time-consuming and tiresome. Also, the accuracy of diagnosis will largely depend upon individual expertise. A computer-aided diagnosis (CAD) system can significantly improve accuracy and reduce diagnosis time. In the proposed automated ulcer detection system, relevant features of the histogram of oriented gradients (HOG) and uniform …local binary patterns (LBP) are optimally selected by high variance low correlation (HVLC) based novel feature selection technique and the classification task is performed using support vector machine (SVM). Proposed feature selection technique reduces the feature set by 96.53% and outperforms five other state of the art feature selection techniques. The performance of proposed system is compared with other systems and it performs with accuracy, F measure and sensitivity of 95%, 95.12%, and 97.5% respectively. Show more

Keywords: Automated ulcer detection, CAD, capsule endoscopy, feature selection, HVLC

DOI: 10.3233/JIFS-182883

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1491-1498, 2019

Authors: Xing, Zhikai | Jia, Heming | Song, Wenlong

Article Type: Research Article

Abstract: Considering that the 3D pulse-coupled neural network (3D-PCNN) model has the deficiency of high parameter complexity and low accuracy in color image segmentation, swarm intelligence optimization algorithm is adopted to optimize the image segmentation process. In this paper, whale optimization algorithm (WOA) is adopted to optimize the 3D-PCNN model parameters E and β . The improved product cross entropy (IPCE) is chosen as the fitness function of optimization algorithm. WOA algorithm is used to find the minimum fitness function, and the corresponding optimal parameters are obtained. Through the study of image segmentation in the image segmentation library of University of …Berkeley and the actual plant canopy image, the maximum entropy value and the Tsallis entropy value are compared and analyzed. Experimental results illustrate that the proposed algorithm can obtain more accurate image segmentation effect and higher segmentation rate. Show more

Keywords: 3D-PCNN, color image segmentation, whale optimization algorithm, improved product cross entropy

DOI: 10.3233/JIFS-182893

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1499-1511, 2019

Authors: Zuo, Wen-Jin | Li, Deng-Feng | Yu, Gao-Feng | Zhang, Li-Ping

Article Type: Research Article

Abstract: With the development of modern property service industry, the property perceived service quality (PPSQ) evaluation data is characterized by multiple evaluation subjects, complicated data structure and large scale data. Since the traditional decision-making methods are difficult to solve the above similar problems, this paper proposes a large group decision-making (LGDM) method of generalized multi-attribute and multi-scale (MAMS) based on the linear programming technique for multidimensional analysis of preference (LINMAP). In this method, the large-scale heterogeneous data of expert preference and user evaluation is fused. The decision matrix of generalized MAMS is used to process user evaluation information. The positive ideal …solution (PIS) and the attribute weights are determined by the LINMAP model. The comprehensive evaluation values are calculated and hereby the alternatives are ranked order. According to the relation between attribute weights and preset values, a mechanism for identifying invalid data is designed. This paper analyzes a set of survey data of PPSQ for the four public construction projects in the same city. The analysis results show the validity and rationality of the proposed method, and develop the property service evaluation theory. Show more

Keywords: Large group decision-making, generalized multi-attribute and multi-scale method, linear programming technique for multidimensional analysis of preference, large-scale heterogeneous data processing, property perceived service quality

DOI: 10.3233/JIFS-182934

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1513-1527, 2019

Authors: Abbas, Syed Zaheer | Ali Khan, Muhammad Sajjad | Abdullah, Saleem | Sun, Huafei | Hussain, Fawad

Article Type: Research Article

Abstract: Pythagorean fuzzy sets (PFSs) and interval-valued Pythagorean fuzzy sets (IVPFSs) play a vital role in decision-making processes. In this paper based on PFS and IVPFS we introduce the concept of Cubic Pythagorean fuzzy set in which membership degree is an IVPFS and non-membership degree is a PFS. We define some basic operation of Cubic Pythagorean fuzzy numbers (CPFNs). We define score and accuracy functions to compare CPFNs. We also define distance between CPFNs. Based on the defined operations we develop Cubic Pythagorean fuzzy weighted averaging (CPFWA) operator and Cubic Pythagorean fuzzy weighted geometric (CPFWG) operator. We discuss some properties of …the developed operators such as idempotancy, boundedness and monotonicity. Moreover, we give a multi-attribute decision making, to show the validity and effectiveness of the developed approach. Finally, we compare our approach with the existing methods. Show more

Keywords: Pythagorean fuzzy sets, interval-valued Pythagorean fuzzy sets, Cubic Pythagorean fuzzy sets, Cubic Pythagorean fuzzy weighted averaging (CPFWA) operator, Cubic Pythagorean fuzzy weighted geometric (CPFWG) operator, decision making

DOI: 10.3233/JIFS-18382

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1529-1544, 2019

Authors: Rahman, Atta

Article Type: Research Article

Abstract: In this paper, a numerical solution to the Troesch problem using a memetic computing technique is proposed. In this regard, a linear combination of Gaussian radial basis functions (GRBF) as approximate mathematical framework is suggested. A set of unknown yet adaptable parameters are modeled in a cost function, representing the trial solution. Differential Evolution (DE) algorithm crossed with Interior Point algorithm (IPA) and Pattern Search (PS) are utilized to find the unknowns. Numerical results based on three special cases of proposed scheme are compared with the exact solution as well as many other numerical and classical approximation methods. Analysis reveals …that the proposed scheme is promising in terms of accuracy and conformation to the exact solution. Show more

Keywords: Troesch problem, differential evolution, gaussian radial basis function, boundary value problem, pattern search (PS), interior point algorithm (IPA), memetic computing (MC)

DOI: 10.3233/JIFS-18579

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1545-1554, 2019

Authors: Zhang, Haidong | He, Yanping | Ma, Weiyuan

Article Type: Research Article

Abstract: Through a combination of hesitant fuzzy sets with rough sets, this study develops a single-granulation hesitant fuzzy rough set model from the perspective of granular computing. In the multi-granulation framework, we propose two types of multi-granulation rough set model, called the optimistic multi-granulation hesitant fuzzy rough sets and pessimistic multi-granulation hesitant fuzzy rough sets. In the models, the multi-granulation hesitant fuzzy lower and upper approximations are defined based on multiple hesitant fuzzy tolerance relations. The relationships among the single-granulation hesitant fuzzy rough sets, optimistic multi-granulation hesitant fuzzy rough sets and pessimistic multi-granulation hesitant fuzzy rough sets are also investigated. Finally, …we develop an approximation reduction approach of multi-granulation hesitant fuzzy rough sets to eliminate redundant hesitant fuzzy granulations with a detailed example. Show more

Keywords: Single-granulation hesitant fuzzy rough set, Multi-granulation hesitant fuzzy rough set, Hesitant fuzzy granulations, Approximation reduction

DOI: 10.3233/JIFS-18586

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1555-1567, 2019

Authors: Wang, Fang | Li, Xiao-Tong | Zhao, Jin | Chen, Shao-Hua

Article Type: Research Article

Abstract: The multiple attribute decision making (MADM) with interval grey uncertain linguistic (IGUL) is a topic of current interest, and various methods have been developed. However, few approaches taking the behavioral characteristics of the decision maker into account. In this paper, an extension of TODIM (i.e., an acronym in Portuguese of interactive and multiple attribute decision making) method, in which three behavioral characteristics of the decision maker (i.e., risk aversion, reference dependence and loss aversion) are considered, is proposed. First, the δ -Hamming distance is defined to deal with the interval grey uncertain linguistic variables by considering the level of the …decision maker’s risk aversion, and its distinguish ability is validated by compared to the classical Hamming distance. Then, the details of the TODIM· SIR method is demonstrated: (i) considering the reference dependence behaviour of the decision maker, the positive-ideal alternative (i.e., PIA ) and the negative-ideal alternative (i.e., NIA ) are defined, and the gain and loss degrees of each alternative relative to NIA and PIA are computed based on the δ -Hamming distance; (ii) taking the loss aversion behaviour of the decision maker into account, the perceived dominance degree of the decision maker for the gain and the loss is calculated; (iii) according to the idea of the Superiority and Inferiority Ranking method (i.e., SIR, an outranking method), the Gain-flow and the Loss-flow are defined, and the partial ranking orders and the complete ranking order are obtained. Finally, two numerical examples are given to illustrate the robustness and validity of the method, and a comparative analysis is also conducted to compare the TODIM· SIR method with both the classical TODIM method and the classical SIR method. Show more

Keywords: TODIM, SIR, Multiple attribute decision making, interval grey uncertain linguistic

DOI: 10.3233/JIFS-18654

Citation: Journal of Intelligent & Fuzzy Systems, vol. 37, no. 1, pp. 1569-1581, 2019