The Effect of Brand Image on Consumptive Behavior of Adolescent Girls in Palembang

This study aims to empirically examine and analyze the effect of brand image on the consumptive behavior of adolescent girls in Palembang. The study population was young women aged 10 to 24 who made purchases at malls located in Palembang. The sample studied as research respondents was 100 people with the questionnaire distribution technique used was accidental sampling. The analysis technique used to estimate the research model is Ordinary Least Square (OLS). The estimation results show that the brand image variable has a positive and significant effect on the consumptive behavior of adolescent girls in Palembang.

I. INTRODUCTION
A survey states that 63% of consumers at a mall who conduct shopping transactions are teenagers and consider the shopping activities to be merely entertainment or recreation [32]. Another research mentions the details of youth activities in the mall today are hangouts (44.60%), food purchases (14.80%), purchases of school supplies (10.50%), walks (9 , 40%), clothing purchases (9.00%), money to save (8.80%), purchase of tapes (2.30%), and accessories purchases (0.60%) It can be concluded that these teenagers are more oriented towards consumptive lifestyles [8]. The research proves that the level of consumptive adolescents is included in the high class so that the phenomenon in the economy is that the main role is that people who live in urban areas have a yery large relation between consumptive behavior with adolescents, consumptive behavior will continue to be a part of the adolescent's self [28]. Based on the Table 1, adolescent girls at the age of 11-20 years were in 2018 with 366,712 people and then teenage boys at 12-21 Years were mostly in 2016 at 373,767, 375,355 people and in 2018 they were 386,441 people. Furthermore, over the age of adolescent girls at the age of 11-20 Years at least be in 2017, namely 364,278, 346,874, and 343,807 people and then the age of male adolescents at the age of 12-21 years at least are in 2017 which is 383,697, 364,818, 358,442 soul Furthermore, adolescents are a group of people who are easily and easily influenced by excessive consumption patterns of goods including clothing, technology and food [23]. In addition, adolescence is the age of consumptive orientation, meaning that adolescence is a form of expression and ex-experimental behavior to try new things.
Supported by the opinion of Alwisol [4], where the search for something new is an attempt to find their identity. According to Putri and Hadi in Pratiknyo [28], the age range is between 11-21 years for women, and 12-21 years for men. The age range is the age of a person who studies at High School (SMA) to Higher Education (PT) and who has worked and is classified as an early and late adolescent group, Monk in Pratiknyo [28].
Changes that occur in adolescents, namely the psychological aspects and physical aspects. Teenagers always try something new because the curiosity is too high. This brings more confusion among adolescents, especially in adolescents, girls. Adolescents are aware of social support influenced by attractive appearance based on what is worn and owned, so it is not surprising that the purchase of cosmetics and purchases of clothing and accessories in early adolescence are considered important [26]. Adolescent girls spend more money than men for appearance needs such as clothes, make-up, accessories, shoes [29]. Then According to Zebua and Nurdjayadi [34] based on the Consumer Psychology approach, adolescents, especially Young women, are groups of consumers who have distinctive characteristics such as being easily attracted to fashion, easily enticed into advertisements and seduction of sellers, not frugal, less realistic, romantic, and impulsive.
On the one hand, adolescents have concepts and principles about beauty, but on the other hand they sometimes can't resist the offer of beautiful concepts so the decision to use products with various well-known brands because they want to look more attractive. Many young women buy fashion products and accessories in stores such as clothes, bags, sandals, shoes, and so on. They often buy the same fashion products and goods with their friends or even compare their possessions with those of their friends to see who is more trendy. The increasing number of shops that provide various fashion products for young women also encourages teens to behave in a consumptive manner.
Consumptive behavior is familiar to us. This consumptive behavior seems to be a habit in Indonesian society. Consumptive behavior is behavior that cannot be separated from everyday life, both humans who live in developed countries and in developing countries such as Indonesia.
According to Sumartono [30], consumptive behavior is behavior that is no longer based on rational consideration, but rather because of desires that have reached irrational levels again. Consumers usually shop for goods because the goods are branded, it's all caused by consumers wanting to raise the status of the surrounding environment. Consumer behavior is a human tendency to consume unlimited (Indonesian Consumer Foundation). Another opinion was put forward by Agustina [3] who said that consumptive behavior is as a tendency for someone to overdo something and not plan.
Consumptive behavior is not far from buying activities. According to Assauri [7] there are 4 aspects that influence shopping activities: pride because appearance, attract the attention of others, consumers want to appear different from others, and join in. Consumers in shopping must recognize or know what they need, such as information about products, brands and other things related to the product. Consumers will be able to determine where and where they should shop, decide whether to shop from the same merchant or not, choose how to shop, show satisfaction with service or product qualitY and ultimately always be loyal to use the brand. Strong brands can help in building an identity in market competition [1]. Consumptive behavior in adolescent girls is an act that is clearly seen in obtaining, consuming, and consuming industrial products and services without limits and being out of control marked by a luxurious and excessive life.
The understanding of brand image (Brand Image) according to Mustikarillah [25] is the way a brand created by the manufacturer affects consumers of their products or directly to the company. The creation of a positive brand image results in the introduction of a brand to the market or consumers that are getting bigger and better. This condition can be stated by the producers able to create a product that is accepted in the community. When this condition occurs due to the producers in making and developing their products it can be said to be superior compared to competitors who issue the same product. When brand image awareness (Brand Image) can be created with a good and stable condition, due to the presence of media that provides access to communication between producers or companies against consumers or target markets that are predetermined by the company.
For companies, Brand Image is a public perception of a company's identity. This perception is based on what the public knows or thinks about the company concerned, therefore the same company may not necessarilY have the same Brand Image in front of people. Brand Image of a company or a product is formed by the introduction of the product in an information, it is necessary to do an advertisement or a promotion of the product to be bought because with advertising, a consumer will be curious about the product to be purchased, and the need for ad appeal in the form of characters from the ad.
Brand Image plays an important role in any business to make the business successful Malik [24]. In shopping for goods, teenagers tend to pay attention to the brand. Goods that are well-known brands that are widely used by artists often become a benchmark for teenagers in shopping for goods. There is pride in teenagers who use goods with the same brand that is used by the artist. According to Jr.
Stephen [18] loyal customers are more likelY to allocate a brand and recommend it to relatives, friends and other potential customers.
Research of Fristiana [13] brand image is an interpretation that is accumulated to various information that can be accepted by consumers. One thing that is interpreted is information about the product and the company that houses the product. But the results of research conducted by Adnan [2] on An Analysis of the Factors Affecting Online Purchasing Behavior of Pakistani Consumers shows that website design and aesthetics have a positive and insignificant relationship with online shopping behavior. These different research results indicate a research gap. Ferista [12] states that risk perception is an important component in information processing carried out by consumers. The high risk perception that arises in the minds of consumers can be a barrier to shopping online. Consumer reluctance to do online shopping is a threat to online businesses, therefore marketers must be able to formulate appropriate marketing strategies to minimize or even eliminate risk for consumers. Research by Brian Gumelar [16], shows that brand image has a positive and significant effect on shopping decisions, this research was conducted on wardah cosmetic products. This proves that the brand image indicates a strong relationship with shopping decisions, with the achievement of the level of customer satisfaction resulting in a decision from the consumer.
Based on this description, the problem examined in this study is the effect of brand image on consumptive behavior of adolescent girls in Palembang. The benefits of research are expected to increase knowledge in the field of marketing management and provide input to producers in formulating marketing strategies by understanding consumer behavior.

A. Consumptive Behaviour
The consumptive behavior of Indonesian people is considered excessive when compared to the nations in Southeast Asia [31]. This situation is seen from the low level of savings of Indonesian people compared to other countries such as Malaysia, the Philippines, and Singapore. This proves that the Indonesian people prefer to use money to meet unnecessary needs by behaving in a consumptive manner or living in the world of consumerism which is an absolute requirement for the continuity of status and lifestyle. Living in a world of consumerism regardless of age, gender or social status.
A consumptive behavior is a behavior that no longer buys goods that are really needed, but buys goods solely to buy and try the product, even though it actually does not require the product [1]. Consumptive behavior is the act of someone shopping for an item without any reasonable consideration, where a person in shopping for an item is not based on a factor of need [30]. In addition, according to Sumartono [30], consumptive behavior can be interpreted as an act of using an incomplete product, meaning that a product that has been used by someone has used the same type of product from another brand or can be mentioned, shopping for a gift offered or shopping for a product because many people use these items. [30] states that the indicators of consumer behavior are: (1) shopping for products because of the lure of prizes. Individuals shop for goods because of the prizes offered when shopping for these items, (2) shopping for products because the packaging is attractive. Consumers are very easily persuaded to shop for products that are neatly wrapped and decorated with attractive colors, meaning that the motivation for shopping for products is simply because the product is neatly wrapped and attractive, (3) shopping for products to maintain self-appearance and prestige. Consumers have a high desire to shop because in general consumers have characteristics in dressing, dressing, hair style and so on with the aim that consumers always look that can attract the attention of others. Consumers spend more money to support their appearance, (4) Shop for products based on price considerations (not based on benefits or uses). Consumers tend to behave as indicated by the existence of luxurious life so they tend to use everything that is considered the most luxurious, (5) Buying a product is merely a status symbol. Consumers have a high ability to shop both in dressing, dressing, hair style, and so on so that it can support the exclusive nature of expensive goods and gives the impression of coming from a higher social class. Buying a product can give a status symbol to look cooler in the eyes of others, (6) Use the product because of the conformity of the advertising model. Consumers tend to imitate the behavior of the idol in the form of using everything that can be used by his idol. Consumers also tend to use and try the products offered when they idolize the public figure of the product, (7) The emergence of an assessment that shopping for products with high prices will lead to high confidence.

B. Brand Image
Brand image (brand image) initiallY is the consumer develops a set of brand beliefs about where the position of each brand in each attribute, with the understanding that a collection of beliefs about a brand will form a brand image.
Brand image is a group of brand associations that are formed and embedded in the minds of consumers. Consumers who are used to using a product with a certain brand, will tend to have consistency in purchasing the brand image. Excellence in competition based on brand function can produce a positive brand image and can create performance advantages and material profit for the company in the long run and significant growth potential. In addition, companies that have a strong brand image among consumers will be easy and have alternatives to compete at the level of prices and product specifications.
The brand is the main thing that becomes an outside picture of a product regarding the quality, quantity and size of customer satisfaction regarding a product. Because of this, the brand of an old product that is already running will be a picture of consumers in seeing a product, can even be used in improving the image for its users. There are 3 parts in brand image, namely: 1) The image of the maker, namely some things that are a picture of a consumer to a company that produces goods and services perceived by these consumers.
2) User image, which is the thing that makes a picture of consumers against users or consumers who use a product and service.
3) Product image, that is, as what is described by consumers or customers of the products and services they know.
The brand has the meaning as a message that the company wants to convey in a brand through several accesses, for example advertisements, product names, symbols of the products themselves, and so forth. brand is very closely related to brand image, because brand image is related to how a consumer's description of a product. Often the occurrence of facts on the ground is different from the desires of the messages conveyed by a company, there is a difference between messages captured by consumers and delivered by marketers. So with this in mind, a marketer needs to make plans to disguise the brand message that will be communicated to potential customers or target products and companies.
The dimensions of the brand image consist of: 1) Reputation (good name), a high level or status of a particular product brand.
2) Recognition, which is the level of a brand in being known by consumers, if a brand is not known enough by potential customers, then what is done is to rely on price as its main attraction 3) Affinity (emotional attachment), which is an emotional attachment that occurs in a consumer with a particular brand. A product with a certain brand that is favored by some people will certainlY be easier to make sales, and if a product with a certain brand perceived by consumers has high quality will have a positive impact on the reputation of a product going forward. Affinity in this case is about a positive attachment that makes a consumer like a product with a certain brand. 4) Brand loyalty (brand loyalty), which is about how far a consumer is loyal to the use of a particular brand.

Measurement of Brand Image
Measurement of brand image can be done on a brand by including:

1) Strength (strengthness)
Is covering the advantages possessed by a brand that is physical and not found in other brands. The superiority of this brand rests on the physical attributes of the brand, so that it can be called an advantage when compared to other brands. Included in this strength group are phYsical appearance, product price, the functioning of all product facilities, as well as the appearance of supporting facilities of the product.

2) Uniqueness (uniqueness)
That is the ability to be able to know the difference between a brand and other brands. This impression arises from the attributes that become the differentiator or differentiation with other products. Included in the unique category are price variations, service variations, as well as the appearance or name of a brand and the physicality of the product itself.

3) Favorable
Included in this favorable group are the ease with which the brand is pronounced and the ability of the brand to remain remembered by the customer and the compatibilitY between the brand impression that is in the minds of consumers and the image desired by the company for the brand concerned.

Brand Expansion Strategy
There are 5 choices of brand strategies that can be used by the company in expanding the brand:

1) Line expansion
That is, if the company introduces additional product units in the same product category and the same brand. For example, the Fire Ship that releases instant milk coffee products.

2) Brand extension
Namely the strategy undertaken by the company to issue a new category of products with brands that are alreadY available. An example is Wardah shampoo released by Wardah.

3) Multi Brands
Namely the strategy carried out by a company by adding new products in the same brand category. Example of Indofood with its instant noodle products.

4) Brand new
The company issues a product in one category, but does not use an existing brand, but instead uses a new brand. For example, Coca-Cola released a new product with the Fanta brand of fruit-flavored drinks.

5) Joint brands
Ie, two or even more brands that are combined in one product. For example, Aqua-Danone.

C. Previous Research
A study aimed at finding out the influence of brand image and celebrity endorsers on wardah cosmetics purchasing decisions for students of Yogyakarta State University. Where independent variables namely Brand Image and Celebrity Endorser influence purchasing decisions as the dependent variable. The research shows that all the variables involved are significantlY proven in influencing the dependent variable namely the purchasing decision [16].
Research conducted by Alfian [5] with the title "The Influence of Brand Image (Brand Image) Against Decision Making Purchases of Toyota Kijang Innova at PT. Hadji Kalla Polman branch ". The research model used is the method of observation, interviews, questionnaires and literature studies conducted systematically based on research objectives. From the results of the study showed that the brand image variable consisting of the excellence of brand associations, the strength of brand associations, and the uniqueness of brand associations had a significant influence on the decision making of Toyota Kijang Innova car purchases at PT. Hadji Kalla Polman branch.
In Wagner's research [33] entitled "Shopping Mall Lifestyle" as a Form of Consumer Behavior in Urban Youth: The Case of Teenage Consumers in Three One Stop Shopping Malls in Jakarta ". From these results it can be concluded that the age of beginner shoppers and socialize shoppers ranges between 15-18 years, while real shoppers are 19-22 years old. real shoppers and beginner shoppers are usually women and socialize shoppers are men. Real shoppers go to the mall with the aim to fill their free time, while socializing shoppers to socialize with their friends, and beginner shoppers aim to buy their dailY needs.
Petova Research [27] is about "Consumptive Behavior towards Fashion in Metrosexual Men who barely earn". From these results it can be concluded that the consumptive behavior possessed by the subject can be seen from the aspect of impulsive buying, where the subject often buys an item based on his desire only and never planned it, the aspect of purchase is irrational and for the sake of status, where the subject buys the item due to his prestige of the goods branded items to be impressed as modern people, extravagant or excessive purchasing aspects, where the subject is extravagant in spending money, and aspects of buying out of reach, where the subject often forces to buy an item at a high price even though insufficient finances that result in the subject in debt.

D. HYpothesis Development
Ho: Brand Image does not affect the consumptive behavior of adolescent girls.
H1: Brand Image has a positive and significant effect on the consumptive behavior of adolescent girls.

III. RESEARCH METHODS
This research was conducted in Palembang City Mall with the object of research being teenagers who shop at Palembang City Mall area, with productive adolescents ranging from 12 Years -21 Years. The sample method in the study was calculated using the Slovin formula, the number of samples obtained based on these calculations were 100 teenagers in the Palembang City Mall. The analysis technique used in this study uses simple linear regression analysis analysis by including testing the validity, reliability and significance test (f test, t test and R squared). The relationship equation model in simple linear regression analysis is as follows: PK = a + bBI i (1)

A. Validity test
Validity indicates the extent to which a measuring device is used to measure what is measured. The waY to do this is by correlating the scores obtained on each question item with the total individual scores.
Validity testing is done with the help of a computer using the SPSS for Windows Version 22.0 program. In this study validity testing was conducted on 100 respondents. Decision making is based on the calculated value (Corrected Item-Total Correlation)> rtable of 0.195, for df = 100-1 = 99; = 0.05 then the item /then the item / question is valid and then the item / question is valid and otherwise.

Test Validity of Brand Image Variable Questionnaire
Based on the calculation results of the validity test of the brand image method with 12 question items are as follows: Based on Table 2, it can be seen that all questions for the training method variable have a valid status, because the value of rcount (Corrected Item-Total Correlation)> rtable is 0.195

Test Validity of Consumptive Behavior Variable Questionnaire
Based on the calculation results of the validity test of consumptive behavior variables with 8 question items are as follows. Based on Table 3. it can be seen that all questions for the consumer behavior variable have a valid status, because the value of r count (Corrected Item-Total Correlation)> rtable is 0.195.

B. Reliability Test Results
Reliability test is performed on question items that are declared valid. A variable is said to be reliable or reliable if the answers to questions are always consistent.
The reliability coefficient of the instrument is intended to see the consistency of the answer items provided by the respondents. The analytical tool uses the split half method by correlating the total score of odd versus even numbers, then the reliability is calculated using the formula "Alpha Cronbach". The calculation is done with the help of the SPSS computer program. The reliability for each variable results are presented in the following table:

Research Model Estimation Results
The results of the regression equation the effect of brand image on consumer behavior in Palembang City Mall can be shown in Table 5: Estimation results show that the coefficient value for Brand Image (BI) is 0.397 and has a positive relationship, which means that when the brand image variable rises, the consumer behavior will increase by 0.397 with a probabilitY value of 0,000 <0.05 degrees of error of 5% so it is statisticallY significant for consumptive behavior.

Significance Test (F Test and t Test) F test
The F test results obtained are presented in Table 4.5 below:

Source: Data processed, 2019
Based on Table 6, the Fcount value is 47,574 and the significance value is 0,000, then the Ftable is calculated with df 1 (the number of free variables as much as 1) and df 2 (the number of samples 100-1-1) with a significance level of 0.05. 3.94. Describe that Fcount> F table with a significance value below 0.05. Thus rejected H0 means Online Shopping has a significant effect on Consumptive Behavior.

Result T Test
T test is used to determine whether the independent variable partially influences the dependent variable or not. T test results shown in table 5. Table 5 shows that the tcount of brand image variables on consumptive behavior was 6.897 with a ttable value of 1.660, a significance of 0.000 less than 0.05. Based on the decision criteria tcount> ttable (6.897> 1,660), meaning that H0 is rejected means that brand image has a significant effect on consumer behavior

The Coefficient of Determination of the Consumptive Behavior Model
Following are the results of R Square the influence of brand image on consumer behavior in Palembang City Mall; The R-square value in the regression equation is 0.327 or 32 percent, meaning that the variation of the independent variables used in the Brand Image model is able to explain 32 percent of the variation than the consumer behavior variable, while the remaining 68 percent is explained by other variables not included in this research model .
Based on the regression analysis that the first hypothesis statement that Brand Image has a positive and significant effect on Consumptive Behavior is proven. This can be indicated by the significance value (P Value) of 0.003 which is smaller than 0.05 and a regression coefficient of 0.260. It can be concluded that the higher the Brand Image given by consumers to the Mall of Palembang, the higher the Consumptive Behavior.
The second hypothesis statement that Online Shopping has a positive and significant effect on Consumptive Behavior is not proven. This can be indicated by the significance value (P Value) of 0,000 which is far above 0.05 and the value of the regression coefficient of 0.320. It can be concluded that there is a positive but not significant effect on Consumptive Behavior. Based on the results of research that has been done it can also be seen that from the Brand Image and Online Shopping variables, the direct evidence variable which is the most dominant influence on Consumptive Behavior Where this variable has a positive and significant influence. The Brand Image Factor and Online Shopping have a positive but not significant effect. While the Online Shopping factor according to the results of this study does not have a positive and significant effect on Consumptive Behavior.

A. Conclusion
Based on the analysis and discussion of the Effect of Brand Image on Consumptive Behavior in Adolescent Girls in Palembang, it can be concluded that: Brand Image has a significant effect on Consumptive Behavior of adolescent girls. This is evidenced from the t svalue of 6.897 with a significance value of 0,000 less than 0.05 (0,000 <0.05), and the regression coefficient has a Brand Image of 0.397.

B. Suggestion
Based on the results and conclusions of this research, suggestions are as follows:

1) For Companies
The consumer's decision to make a purchase with the Brand Image motif is reasonable because the search for pleasure from consuming the product. Factors in Brand Image motives are very subjective, but retailers can arouse consumer shopping excitement by: a) Selling new products that are in accordance with the development trends b) Attract consumers by giving discounts on certain products. c) Employ employees who are friendly, good and good looking. d) Outlets / stores are arranged and designed as attractive as possible so as to make visitors who come feel comfortable.
Feelings of pleasure and satisfaction from a product can arouse consumer interest to make a purchase.

2) For Further Researchers
For further researchers who want to research or continue this research, it is recommended to continue or develop this research by looking for other factors such as advertisements, discounts, visual merchandising, fashion lifestyle, and others that can influence Consumer Behavior in HYpermarkets. In addition to using the questionnaire technique, interviews can also be developed to find out the motives of consumers to do Brand Image so that the data obtained is more complete and can reduce subjective data.


Integration of Eco-centric Views of Sustainability in Port Planning

The sustainability approach commits to conserving natural resources and biodiversity. In ports, many efforts that encourage improvement in sustainability exist, such as sustainable ports, eco-ports, or green ports. However, whether the current planning approaches for sustainable ports, eco-ports, and green ports can effectively achieve sustainability remains a question. This study aims to discuss this issue through a literature review. The main findings include (1) the current sustainable port planning following the ambitions of sustainable development and aiming to fulfill this generation’s needs; (2) the eco-port planning approaches emphasizing environmental protection; (3) the planning approaches for green ports that have emerged within environmental management and give attention to the ecological issues; (4) all of the three approaches prioritizing environmental issues. We argue for the integration of eco-centric views for sustainability in port planning from a maritime supply chain perspective, and based on this, the concept of the green port is proposed. This study provides broad and mindful information regarding port sustainability education and can help foster innovation in order to face the challenges in sustainability.

Introduction
Sustainability, the need to ensure a future for the Earth [1], emerged as the perpetuation and enhancement of the natural ecosystem in the 1970s [2]. Given the adverse impact of growth and development on global ecosystems within the limits of the biosphere's carrying capacity, the Brundtland report set a blueprint for sustainability to achieve economic growth, social responsibility, and environmental quality in 1987 [3]. The United Nation's 2030 Agenda currently interprets sustainability as the maintenance of well-being, which concerns prosperity, planet, and people and seeks the continuity of ecological systems and values irreplaceable natural resources [4]. Exploring the theoretical basis of these concepts, eco-centrism, which includes humanity and the natural ecosystem as a whole and views all life as equal, has been recognized [5]. Understanding the fact that the natural environment and resources are fundamental for human existence and development, this eco-centric approach became a key move towards sustainability [6]. Human activities must be connected in order to conserve natural resources and biodiversity as a result of the changing environment and the loss of biodiversity [5,7]. Taking the case of maritime activities, the World Association for Waterborne Infrastructure (PIANC) laid stress on the "working with nature philosophy" to exploit the ecosystem-based solutions for sustainability [8].
Due to pressures from environmental non-government organizations, stakeholders, and the public, industries, including the port industry, have integrated sustainability into their business reports [9,10].
Many port sustainability issues, such as energy-saving, air quality, emission-reducing, natural resources conservation, and waste handling, have been raised by international organizations, governments, port authorities, and companies [11]. In recent decades, well-known initiatives of sustainable ports, eco-ports, and green ports have been developed and implemented to address growing port sustainability concerns [10,[12][13][14]. When moving towards the long-term goal of sustainability, port planning has been regarded as a critical tool in port development [15]. However, the literature rarely concerns the sustainability-oriented planning approach in ports [16]. There is a question about whether the current planning efforts of sustainable ports, eco-ports, and green ports employ the eco-centric approach to encourage the achievement of sustainability.
Thus, this study aims to review the current approaches of planning for sustainable ports, eco-ports, and green ports, and to identify if the existing ones can capture the ecological requirements of sustainability. The exploration of sustainability in ports may not only help the development of creative perspectives but also help direct decision-makers to provide effective strategies for ensuring sustainability in ports.

Methods
The literature review, an evidence-based approach, has been known as a key scientific tool to help develop a knowledge base for an academic inquiry [17]. A structured literature review, which includes the processes of collecting data, refining the initial search results, and analyzing the remaining literature, has become popular for its transparent and replicable work [18]. This study adopts a structured literature review method to identify and manage the literature, and employs content analysis to discern reliable findings and give rise to a discussion [18]. In this research, there are two data sources-one is searched publications from the Scopus database for its broad coverage, and the other is from the official websites of international, regional, and local organizations selected by experts consulting from representative perspectives of the green port, sustainable port, and eco-port (see Table 1). Keywords of "green port", "sustainable port", and "eco-port" combined with "planning", separately, were used for the two-part search.  (10) Physics and Astronomy, (11) Immunology and Microbiology, and (12) Medicine, there were 83, 1, and 13 papers that remained for data analysis. Additionally, the official website search identified 15 documents associated with planning for the sustainable port, eco-port, and green port.

Current Concepts of the Sustainable Port, Eco-Port, and Green Port
The United Nations Conference on Trade and Development (UNCTAD) linked sustainable development, which was defined by the World Commission on Environment and Development, to ports in 1993 [19]. Since then, sustainable ports have drawn much attention regarding the environment and development for satisfying humans' needs. In 2013, the Working Group of the World Association for Waterborne Infrastructure (PIANC) suggested that sustainable ports should be based on "an economic green growth strategy", "working with nature philosophy", "corporate social responsibility", and "stakeholder participation" [12]. As with eco-ports, the European Sea Ports Organization (ESPO) initiated a project entitled EcoPorts, which emerged as a port that coexisted with the environment [20], and highlighted the awareness of environmental protection and the improvement of environmental management [14,20]. Entering the 21st century, the concept of the "green port" has been widely accepted as the balance of environmental challenges and economic demands, and the Working Group of the PIANC proposed that green ports should "understand the environment and human uses" and "work with nature philosophy" [8].

Efforts of Sustainability Planning in Ports
As early as 1993, the United Nations Conference on Trade and Development (UNCTAD) initially proposed policies and strategies for sustainable development in ports [19], and the EcoPorts Tools and Certification scheme was implemented in Europe [21]. In 2000, the Urban Harbors Institute (UHI) at the University of Massachusetts, Boston, provided some planning suggestions regarding environmental management and technology for America's green ports [13]. In the past two decades, world associations and regional governments have paid much attention to providing guidance for the planning of green ports, sustainable ports, and eco-ports [8,22], and many related planning efforts for individual ports, like the Port of Long Beach and the Port of San Diego, have been conducted [23,24].
Additionally, scholars have paid attention to analyzing and evaluating the current status of environmental performance in ports and provided indicators of and ideas for sustainable or green port planning [25]. Guos Ong et al. [26] and Wu [27] tried to integrate ecological planning views into green port planning.

Approaches to Port Planning for Sustainability
Based on the papers and documents obtained, the approaches for sustainable port planning, eco-port planning, and green port planning can be summarized here.
(1) Sustainable port planning: • The UNCTAD provided the planning approach of sustainable development for ports in 1993, which includes project objectives; the pre-feasibility study of the initial environmental assessment; feasibility study; environmental impact assessment, formulation, adoption, implementation, and monitoring or evaluation [19].

•
The PIANC offered guidance for port authorities to build sustainable ports in 2013, which embraces defining sustainable ports to meet the needs of present and future generations, analyzing the roles of port authorities, identifying the environmental and sustainability issues in ports and related logistic chains, and strategies formulation [8,12]. (SDGs) [28]. This program will communicate the missions and objectives, and develop further projects and initiatives [28].
(2) Eco-port planning: • The ESPO provided a certification scheme for eco-ports, which includes the processes of self-diagnosis, port environmental review, and certification [21]. In 2012, the Green Guide was published by the ESPO in order to structure the approach for port environmental management and sustainability, which comprises setting a vision to improve environmental performance and environmental management [29].

•
In 2011, the Port of Osaka provided a planning model for eco-ports, which includes protecting the natural environment and minimizing the environmental damages caused by port development [20].
(3) Green port planning: • The Urban Harbors Institute at the University of Massachusetts, Boston, presented an approach for the environmental management of America's green ports in 2000, which includes avoiding, preventing, minimizing, mitigating, or remediating the environmental impacts related to port development and operations [13].

•
The Port of Long Beach provided policies for a green port in 2005, by adopting specific environmental principles, setting goals, establishing specific metrics to measure progress toward meeting the goals, designing environmental programs, and making specific incentives and legislative proposals [23].

•
The Port of Sydney offered guidelines for green port construction in 2006, which provide strategies and practices to be both environmentally friendly and commercially viable [30].

•
The San Diego Unified Port District set goals and objectives in the areas of improving water quality, conserving energy, reducing air emission and waste, implementing a sustainable building, and increasing employees and the public's sustainable awareness, so as to build a green port in 2008 [24].

•
In 2010, the Maritime and Port Authority of Singapore encouraged ocean-going vessels to reduce emissions such as sulfur oxides and nitrogen oxides, and use clean fuels for achieving a green port [31].

•
The Ministry of Transport of the People's Republic of China provided opinions to promote the sustainable development of coastal ports in 2011, which proposes green strategies including energy-saving, emission-reducing, and ecological protection based on the identification of the problem [22]. Another opinion provided green strategies for a green port by the Ministry of Transport, which include resources-saving, energy efficiency improvement, emissions-controlling, and environmental protection based on the development goals set by the government [32]. In 2018, the Ministry of Transport provided an action plan draft to promote green port construction (2018-2022) in 2018, which proposed green development strategies including low carbon and circular, resource conservation, pollution prevention, and ecological protection based on the development goals set by the governments [33]. environmental friendliness, and social responsibilities for protecting the environment and ecology in the port area through an assessment of status [10].
We can acknowledge that the current sustainability approaches in port planning are problem-/data-driven or vision-/goal-oriented. The problem-or data-driven approaches mainly rely on the assessment of the impact of port activities and can be characterized as bottom-up. The visionor goal-oriented approaches have been widely used in planning by international organizations and associations, governments, and port authorities. Most of the top-down approaches have offered strategies or actions to implement sustainable ports, eco-ports, and green ports. Both approaches highlight environmental issues.

Discussion
According to the literature review, the initiatives of sustainable ports and eco-ports emerged earlier than those of green ports. All of these concepts give much attention to environmental issues, and recent ideas of sustainable ports and green ports use a "work with nature philosophy" [8,12]. For guiding these port developments, plenty of practical planning for sustainable ports, eco-ports, and green ports from international, regional, and local organizations have been identified, while only a few papers have focused on port sustainability planning. Probably because of different systems of port governance in different areas, for instance, the Ministry of Transport of the People's Republic of China provided national strategies to plan a sustainable or green port [22], but the most green or sustainable efforts in the United States were in the private sector [23]; the current port sustainability-oriented planning was lacking a coherent policy. Nevertheless, through the bottom-up problem-/data-driven or top-down vision-/goal-oriented planning processes, sustainable port planning has followed the requirements of sustainable development and attempted to fulfill the needs of present and future generations. Compared with eco-port planning, which commits to improving environmental performance [37], green port planning, to some extent, is concerned with natural conservation [10] and ecological protection [33]. The distinction between the two approaches concerns the development objectives and the satisfaction of human needs or the maintenance of the natural ecosystem's intrinsic value [5]. Taking sustainability education as an example, for the former, people would be educated to protect the environment to serve human interests, rather than the "unity of nature and humanity" from ancient Chinese philosophy.
However, according to the previous studies by Wu, Zhang, and Luo [18], a combination of top-down strategic focuses with bottom-up assessment information is necessary in order to improve planning effectiveness, for overcoming the limitations of relying mainly on either limited data or the planners' subjective judgment. In addition, even though some organizations such as the PIANC started to relate logistics chain concerns with port planning, the majority of current approaches still concern the port itself. Owing to ports being the nodes of logistics chains in the context of globalization and larger-sized vessels, port sustainability planning should do more work on the collaborative research-practice maritime supply chain to guide the maritime industry towards sustainability.
Moreover, the conservation of natural ecosystems has already been considered as the key to sustainability, based on the fact that "planet Earth is an end-in-itself" [38], and that people are part of nature and ecosystems [39]. Based on the review results, we found that the current sustainability approaches for port planning have limitations for capturing the ecological essence of sustainability. The current sustainable port planning views, aimed at the fulfillment of human needs, make it difficult to maintain natural resources because of human preferences. Planning for eco-ports recently failed to prioritize nature conservation [37], which may lead to the slow progress of the sustainability approach. Although green port planning raised ecological awareness, a sustainability approach, namely green development, has not been realized. The green development approach has been proven as a good choice for achieving sustainability by Wu, Zhang, and Luo [5], because of its eco-centric theoretical bases, and the objective of conserving the natural resources and biodiversity. Fortunately, in 1998, the preferred sustainability approach was implemented in the real estate industry so as to integrate ecology into construction [40]. Some countries and cities have also used green development to transform their developments; for instance, China has made green development a development path [41].
In this study, we suggest the green port as a good approach towards sustainability, and the combination of green development in the theoretical bases and objectives may lead to more specific and mindful implications, as follows: • Integrating ecological issues such as biodiversity [10], natural resources conservation [10], and ecological risks caused by oil spoil and non-routine discharges in port development.

•
Considering the logistic chain from a supply place to a receipt place [42] in port scoping to improve connectivity and add value [43].

•
Combing the top-down strategic sustainability goal with the scientific bottom-up assessment information for port planning.

Conclusions
In globalization and global sustainability, challenges drive practitioners and researchers to develop proactive and collaborative planning for sustainability in ports. Currently, there is a lack of consistent or coherent policy for port sustainability-oriented planning. This study contributes to the review and discusses the existing representative sustainability approaches for port planning. Insights from our broad literature review indicate the following: (1) the current sustainability approaches in port planning are limited to specific problems, historical data, and subjective judgment for port-itself development; (2) approaches for sustainable port planning, eco-port planning, and green port planning prioritized the environmental issues, but ignored the importance of ecological matters; (3) the current planning approaches for sustainable ports, targeted to meet the needs of present and future generations, are not a good choice for sustainability; (4) green port planning did not realize the implications of green development on the sustainability of nature. Through a comparison of the current sustainability approaches for port planning, we adopted green port planning as a preferred approach for sustainability and gave more mindful connotations for consideration.
This study provides a meaningful analysis to help decision-makers and students understand the current status of port sustainability planning, and prompts in-depth thinking about sustainability in ports. Nonetheless, we would like a broader and further discussion on this topic to gradually move towards the long-term goal of sustainability. For this, innovative sustainability education must play a vital role.
In the future, the proposed concept of a green port will impact the establishment of the subsequent approaches and methods from planning areas, planning objectives, planning processes, and priority initiatives perspectives. A collaborative and cooperative research-practice network in port, shipping, and maritime logistics will be of help. A wider discussion would also be to think of other elements by using Key Performance Indicators, such as economic impact and technological innovation, to learn more about port sustainability planning. Furthermore, for better education about sustainability in ports, a lot of ethical searches into current research and practices need to be carried out, which may encourage creative thinking.


A Wire Rod Rolling Mill Digital Twin for the Simulation of the Rolls Replacement Process †

: Smart Manufacturing is a goal to be achieved, and the most advanced manufacturing approaches are being used to pursue this objective. Within this context, industry development aims to attain an intelligent manufacturing using, for example, virtual models that simulate production lines. This paper presents the architecture of a Digital Twin for emulating the rolls replacement process within a wire rod rolling mill. The model is developed in Python, using a backtracking algorithm to select the suitable set of rolls as a ﬁrst basic approach for the validation of the system. It may be used in the future to improve the production system automating the decision for the replacement of rolls as alternative to the current human-decision process.

Introduction
Nowadays, companies are employing the most advanced technologies, such as Artificial Intelligence (AI) and Internet of Things (IoT), to meet the demands of a worldwide marketplace. This inevitably entails an automation of the industrial processes [1][2][3] that improves their competitiveness and efficiency, which increases the quality of the organizations and paves the way for the fourth industrial revolution, noted as Industry 4.0.
Smart manufacturing [4][5][6][7] is a term used to refer to that future state of manufacturing, which is characterized by a range of interconnected automated systems that merge the physical and digital worlds. One way of developing smart manufacturing systems and processes is using Digital Twin technologies.
Digital Twins [8][9][10], also named Digital Shadows, are a way of recreating physical entities virtually based on models of its behaviors. A Digital Twin is never a target by itself, but a way of achieving the organization goals. They are used in several industrial sectors to analyze the data generated, visualize the processes, or optimize the business operations by optimizing the operation and maintenance of industrial installations and manufacturing processes. In the next years, Digital Twins are expected to be implemented by countless industries for multiple purposes such as supply chains, logistics, or production lines.
The rolling process is the most common industrial process in steel manufacturing, which is used for making large length cross section like sheets and plates of steel and aluminum for structures. Rolling mills are used for performing the rolling process. Wire rod is one of the resulting products from the rolling process, which is mostly used as a quality raw material to produce screws, tires, or construction materials among others. It has a hot rolled round section that is turned into wire through cold rolling processes or wiredrawing.
Multiple elements are involved during the wire rod mill operation. The raw material is passed through regular rolls until the required cross-section profile is achieved. Rolls work usually in pairs (at least for the configuration noted as "two high rolling mills," where the rolls rotate in the opposite direction to the movement of the work piece, and the work piece is fed between the rolls) and they are assembled in stands. Every roll in the process has a specific function in the making of the piece. At every stage, there are minor changes in the configuration of the metal. The size of the roll depends on the metal type, thickness, and formability. One of the most important tasks in the wire rod mill case is to determine the set of rolls to be used in the drawing process for a specific set of orders. Rolls are replaced frequently (every several days), because of the wear. Wear depends on various parameters, the most important being the tons of raw material rolled. Once a set of rolls is worn, they must be disassembled. The rolls are usually changed as a whole, or at least all of them in the same area of the rolling mill at the same time. The rolls are not discarded when disassembled, they are reconditioned in a maintenance workshop located in the same facility by grinding the roll and reshaping their tracks. There is also a warehouse where all the rolls of the plant are stored. Each roll is an expensive asset that is carefully managed through its life cycle, since it is provided by the seller until it is finally disposed. The wire rod mill has a series of determining factors which make this process complex: the number of assembled rolls is high (more than one hundred for this kind of rolling mill) and there are several sections, each one with specific requirements depending both on the track where they are going to be assembled and the kind of product to be rolled. There are also diameter restrictions for the rolls, being the fulfillment of those restrictions one of the most important parameters to take into account when changing the rolls. When the rolls are disassembled, they need to be grinded in order to be used again, reducing its diameter, and therefore, its lifetime.
The aim of this paper is to present a new Digital Twin model for the wire rod rolling mill that will allow to develop and simulate autonomous systems as alternative to the current human-decision process. The paper is structured as follows: first, the wire rod process is introduced, paying special attention to the rolls replacement operation. Then, the architecture of the simulator is presented. Finally, the conclusions and future research are featured. The work presented here constitutes a first approach, so only preliminary results are presented.

Theoretical Background: The Behavior of the Wire Rod Mill and the Rolls Exchange Process
A wire rod mill uses billets that are heated in a reheating furnace (around 1.115 • C) as raw materials; these are long products that have a square section whose length is variable. The rolling process has at its beginning a first roughing mill, consisting of three rolling stands, whose goal is to reduce the square section of the billet (150 × 150 mm) to a square section of approximately 112 × 112 mm. Afterwards, the rolling process is divided in two parallel streams, named veins, as it is depicted in Figure 1. Each vein starts with a second roughing mill formed by seven roll stands, which is followed by the intermediate section, with eleven additional rolling stands. Following this, the finishing area is equipped with two sections of rolling stands, the first one named "block" and the last one named "RSM" (Reducing Sizing Mill). These sections are in charge of providing the final quality to the rolled product. The process ends with a pair of rolls for keeping the traction. Finally, the coils of wire rod are formed. Figure 1 shows the outline of the process. The stock of managed rolls in the factory is particularly high, having usually more than 4000 registered rolls, each with its specific features such as dimension, alloys, geometry, etc. The rolls are grinded and shaped with several tracks, as depicted in Figure 2, each having its own state, which can be working, used, or unused, and its properties, such as the number of tons rolled since it was assembled. Each track is used independently of the others of the same roll for a specific assembly and once the track is worn, the roll is disassembled and that track is marked as used, being the roll able to be assembled again if it still has unused tracks. Each time new rolls are received and whenever all the tracks of a roll are used, its tracks are prepared, that is they are grinded, textured, and chromed, resting ready to be used. The rolls always work in pairs, as it is depicted in Figure 1, so when the manager must choose the suitable track of a roll for a stand, that whose geometry and shape are compatible with the stand, two rolls with equal tracks must be chosen for each vein. In those cases, the manager must take into account the roll service life, the number of accumulated rolled tons, and the location in the warehouse of the roll, turning the problem into a highly dimension one that cannot be handled manually. A database is used for registering all the information as it is of great importance to keep track of the roll's life cycle. There are different restrictions; for example, some rolls only suit in a particular section of the rolling mill and there is a diameter difference constraint between the rolls assembled on several rolling stands.
Currently, the operators of these facilities simplify the problem working with predefined roll pairs and using families and groups of similar rolls that are likely to work together. This is inefficient and reduces the flexibility of the roll changing process.

Digital Twin Design Approach
A simulator of the rolling mill has been developed in order to test further different approaches for selecting the appropriate rolls for the stands. The simulator is developed using Python. It is currently running in a Windows 10 operating system, although it could run in any Linux system. A backtracking algorithm is used to find the suitable set of rolls for each scheduled batch of orders, being a batch the set of jobs that the mill performs before the rolls are disassembled.
The general schema of the simulator can be seen in Figure 3. As it is depicted, at the beginning, the variables are initialized. To do that, the simulator receives a JSON file as input with the required values and using them the roll dataset that will be used as the rolls warehouse's stock is created (1). Next, the simulation starts, and, for each scheduled batch of orders, it requests a group of rolls (2) to replace the assembled ones. In order to do this, it has to read the rolls status (3) and once known, it proposes a roll set to be used (4). This part is designed as a separate module, because one of the main goals of this simulator is testing different approaches and comparing results among them. In order to try a first approach that could be used for validation of the present work, a backtracking algorithm has been implemented. The backtracking algorithm is executed for each vein and takes the compatible rolls for each of the stands, that are those which meet the geometry and shape requirements. Then, it checks for each stand its constraints: the two rolls of the same vein must have the same diameter and the diameter restrictions among the rolls of the current stand and the rolls of the previous stand have to be met. If not, it backtracks to the previous stand. A flow chart of the backtracking algorithm is shown in Figure 4. The number of rolls that are checked for each stand is restricted to prevent it from taking too much time. After simulating the rolling of a specific number of tons, the rolls are disassembled because the wear of the tracks that are working and those tracks are marked as used (5). When all the tracks of a roll are marked as used, the roll is sent to the rolls workshop (6), where it is grinded and left ready to work again, reducing the rolls diameter (7) (as consequence of the grinding operation). Otherwise, while the roll has some track available for rolling, it could be assembled again. When all batches of a simulation are performed, the simulator creates several JSON files as outputs with the results and they are displayed graphically. The wear of rolls (and as consequence the reduction of the diameter) is simulated using a model trained with historical data collected from the process. There are N stands from 1 to N. At each step the diameter restrictions for the rolls that have been selected are checked and if they are fulfilled, it checks whether it has compatible rolls for the current stand (i) and goes to the previous stand otherwise (i − 1). If there are not compatible rolls for the current stand, the selection algorithm ends and no set is proposed, but if there are, two rolls of equal diameters are chosen and added to the solution. Then, it checks whether there have been chosen rolls for all the stands (stand = N), and if so, the solution is processed and the algorithm ends. If not, it continues with the next stand (i + 1). Each of the stages of the simulator is described in more detail below.

Algorithm Inputs: Initial Set of Rolls, Batches, and Restrictions
The system generates a set of rolls simulating the situation that could be found in the warehouse. In order to reproduce different scenarios, this initialization is parametrized. The JSON configuration file that the simulator has as input has defined the different types of rolls that are in the sections of the rolling mill (its geometry, the number of positions, and the shape of each of them), the batches scheduled to be done, and its restrictions. The simulator generates a set of rolls that suit that types and the user must choose the algorithm that wants to be used in order to find a set of rolls that can be employed to perform each batch. Here, the users can design their own strategies for selecting the rolls, hence enabling the evaluation of different approaches and comparing the results.

Types of Rolls
The types of rolls are defined indicating the quantity of each, the geometry, shapes of its tracks, number of tracks, and initial and final diameter. The actual diameter of the rolls is generated randomly.

Batches, Jobs Performed with the Same Set of Rolls, and How They Are Defined
Changing the rolls is not an easy or quick operation, so it is avoided as much as possible. That is why the operators group the jobs that the mill has to do (batch) before performing them, reducing the number of replacements. For this very reason, the works that the simulator has to do are not single jobs but compositions (batches) of those that can be performed with the same set of rolls. The simulator is given a set of batches to perform and every batch received consists on each single job that has to be done before the rolls are disassembled. The batches are defined indicating the stands which take part, giving its number, geometry, shape and, for each of the single jobs that are part of it, the quality of the material and the number of tons rolled.

Restrictions Involved in the Rolls Exchange: Diameter Restrictions
Although this type of installation has several types of restrictions, the most important to be considered here are the restrictions between rolls diameters. These restrictions entail that the diameters of the rolls assembled in two consecutive stands must accomplish some constraints. A restriction between two stands with a given diameter (D A , D B ) is applied in a factor (k) and is constrained to a given value (limit) using a relational operator (op). The evaluation of the restriction is performed evaluating the expression (D B − D A )/k op limit, where, as stated before, D B and D A are the diameters of the rolls, k is the factor, op is the relational operator (usually ±), and limit is the value to which the expression is constrained.

Outputs
The batches defined in the configuration file are launched a certain amount of times defined previously and, for each batch, the diameter of the rolls is reduced according to a simple model which has been developed taking into account the number of tons laminated, the initial diameter of the roll, its geometry, and the shape of the track that works. Finally, the results are written to a JSON file and to observe them, they can be shown graphically by plotting the average, median, mode, and range diameters for each geometry and shape as well as the percentage of rolls grinded for each batch. In Figure 5a, the evolution of the average diameter for a particular type of roll, with a particular geometry, number of positions, and shapes of each of them is shown. This measure is an indicator of the remaining life of this set of rolls, and some indicators, as the tons rolled by millimeter could be derived. In Figure 5b, the evolution of the diameter of a particular roll is shown, as it is seen it has been assembled twice, and then the roll was no longer used. In Figure 6, a set of eight batches has been launched fifty times (iterations) and the cumulative percentage of rolls grinded after each batch has been plotted. This is an indicator of how many rolls in the set have been grinded, and thus, their diameter has been reduced. The goal is to reduce diameters in a homogeneous way, to avoid that the differences in diameters in the collection or rolls are enlarged, which would imply a higher difficulty to find compatible rolls, forcing larger diameter reductions, with the consequent reduction in cylinder life. It is indicated in the X axe as iteration-batch, that is number of the execution-number of batch executing. In order to accelerate the process, a filtering strategy is applied first, selecting for each stand just only those rolls that have positions ready to be assembled and whose geometry and shape are compatible with the roll stand. In this way, the number of rolls that are checked for each stand is limited, having also a maximum number of checked rolls for each pair of each stream. In Figure 7, a set of 5600 rolls has been launched without time restriction and the number of pairs of rolls checked for each stream has been limited to ten, as it is seen, when there are no compatible solutions, the execution time boosts significantly, being the number of rolls checked for each stand very small the time it lasts as maximum is about twenty five seconds, and this would increase exponentially with the number of rolls checked. Future rolls reduction approaches must take into account the maintenance of rolls diameter compatibility. If no solution is found, it is considered that it does not exist. The tests performed have been done with a small set of rolls, around 2800, in a Windows 10 desktop computer powered by an Intel Core i5-8500 processor of 3.00 GHz with 8.00 GB of DDR4 RAM, but more accurate tests will be done in the future. The time it lasts in finding a solution is very variable, from 2/100 s to more than three seconds or even not finding one. The results have proved that the probability of the algorithm finding a solution decreases with the generated rolls actual diameters difference; for example, if the randomly generated actual diameter for the rolls is generated between the initial diameter and the final diameter plus eighty percent of the difference, the algorithm usually finds a solution for every batch (higher probabilities of meeting the diameter restrictions among rolls); however, if the actual diameter is generated among the final and half the initial diameter, it can last three seconds or more and usually it does not find a solution at all before ending its execution. If the number of rolls is increased, it is easier to find suitable rolls, as the possibilities of finding compatibles ones are greater; for example, with 5600 rolls, solutions are found when the randomly generated actual diameter is among the initial and the final diameters, being the times very variable, from 2/100 s to more than three.

Conclusions
The developed Digital Twin, although it could be improved, is an accurate representation of the wire rod rolling mill, however, as we stated at the beginning, Digital Twins are never a target by themselves, but a way of achieving the organization goals. In this case, the organization goal that wants to be achieved is an upgrading of the rolls selection system by increasing its efficiency.
Future research could compare the performance of several selection algorithms in order to choose that of greater efficiency. This problem is an example of Constraint Satisfaction Problem, whose natural way of solving is some kind of Domain-pruning strategy such as the current backtracking algorithm implemented in the simulator. First approaches could be performed using asynchronous backtracking algorithm (ABT) [11], an agents distributed algorithm. Following this approach, each stand will be implemented as an intelligent agent. The method needs a total order among agents, each holding exactly one variable. In this case, the order is given by the sequence of stands along the rolling mill, and the variable would be the rolls to be assembled for each stand. During the computation, the agents sent their assigned values to the agents that are connected to them by outgoing links. This approach would give a reference standard to compare with more sophisticated further approaches such as Reinforcement Learning methods.