# Requirements for the Optimal Design for the Metasystematic Sustainability of Digital Double-Form Systems

Authors: Gaurav Dhiman; Gaganpreet Kaur; Mohd Anul Haq; Mohammad Shabaz
Journal: Mathematical Problems in Engineering
 (2021)

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## Abstract

The United Nations defined tenable progress as a development that responds to the demands of the current without adjusting the capacity of further generations to fulfil their own requirements; this is a fundamental idea in this article. This study recognizes three aspects, financial, social, and environmental sustainability, although its emphasis is on the latter. An electronic copy is sometimes characterized a physical thing, a real counterpart, and the data, which indicates the presence of a connector and block for effective and efficient data transmission. This article offers a systematic literature review on the sustainability of designed technology-based systems. This article also introduces the major requirements which can be helpful in designing optimal design for sustainability of a digital double-form system. Many articles on DT have also been chosen since they referenced the studied SLRs and were deemed to be significant for the objectives of this study. Selected and analysed for papers revealed so many flaws and challenges: the boons of are not clear; DTs throughout the result the wheel of life of the DTs is not adequately surveyed; DTs can contribute to cost reduction or to support decision-making is unclear; Internet practice should be improved and better integrated Moreover, it has not been feasible from our study to locate a publication which solely discusses DTs in relation with situational sustainability.


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## Body

## 1. Introducing the Report

An electronic copy (DT) is frequently characterized as an electronic, real body with a physical counterpart and data links including connectors and blocks, which make efficient and efficient transmission of the data possible. It is an electronic representation of a more complicated physical system and despite the various explanations of DT, and it is the original one, and we accept it [1]. The pioneers of this idea are Grieves and Vickers of NASA and presented on product cycle management and recognised. They mention features such as (i) the practical output, (ii) an online representation, and (iii) bidirectional data interfaces between practical and real representation. Output design, modelling, simulation, and optimisation of assets are the primary objectives of DT development [2, 3].Today, the use of DTs has not yet been widespread, but since 2015, scientific research has clearly increased to better grasp their potential. Common instances of DT use include machine tools and consumer products. In all instances, however, a DT must not a big-trust digital replica of a real data. For example, a DT may also be used to represent tangible assets such as whole city (urban digital twin), geographical constructions, and human organs. Other uses of building DTs have been identified for cybersecurity incidents, ergonomics monitoring virtual study, and agricultural optimisation [4]. Output style also constitutes a key and connected element of DT and environmental sustainability since it covers many complicated choices and hybrid-cutting issues, such as safety or tenability (the preference of matters or the use of energy). In addition, output style may affect the planning of a manufacturing line, an additional common use of DTs [5, 6]. This allows mistakes and failures to be anticipated and controlled by means of DT methods utilising data analysis and machine learning techniques as well as artificial intelligence (AI). “Our Common Future” (the United Nations (1987)) defines tenable development as a development that addresses current demands minus adjusting the capacity of further procreation to fulfil needs. This framework is extremely helpful since the idea of the rounded Economics Circular Economy (CE) described as an economic model to reduce limited resource use and is becoming increasingly significant and is strongly linked with the supply chain concept [7, 8]. In 2011, Industry 4.0 has been introduced to a synonym of intelligent manufacturing/manufacturing that corresponds to make statements, like electronic-union making, a dynamic making organisation, CE, and the management of a large volume of DT information [9, 10].The idea of tenable product design, as described by craft of styling buildings, cities, and other artefacts to fulfil the sustainable development goals is closely related to output design optimisation and CE. Output design is not only art but also a choice as to what materials to employ, so that a product is helpful to society. A DT has a closely linked sustainable product design, as described in this study, but our emphasis will be its IT features and advantages [11, 12].This article offers a metaphorical writings survey (i.e., an SLR on SLRs) on DT-based systems sustainability needs. In this sense, the criteria of sustainability are defined as conditions which permit sustainable development. Marten et al. attempted to use general knowledge to help with the criteria specified automatically, a list of overview and IT details for every aspect of sustainability (environmentally, technologically, socially, economically, and individually) and their impact. Furthermore, a new design and ideas have been developed like the impacts between requirements, either negate, impartial, or definite [13, 14]. This new attitude is utilised to build a system that respects the proper balance between various aspects in order to get tenability, the controlled natural language, that systematically and rigorously helps specify requirements and tests such as the IT Lingo Request-and-Status Link (RSL) and it plays an important part in explaining sustainable software needs as, for example, it helps challenges, vulnerabilities, and objectives/solutions [15, 16]. These tools are part of the model-based engineering spectrum, utilising textual and conceptual requirements to enhance the effectiveness, effectiveness, and effectiveness of the study and style and their usefulness [17, 18].This research work introduces an optimal design for the metasystematic sustainability of digital double-form system. The major benefits of using this system are that it will provide more security than previously used systems. Also, the SLR technique developed introduces three stages, which further enhance the sustainability of the system.In short, this article is a meta-SRL (The Saturday Review of Literature) plus an effort at adding fresh credit to the discussion on environmental sustainability. Sustainable development nowadays means responsible resource use, and since DTs may enable the operations to be optimised, this can be a tool to that end. In testing new product, and designers may use to digitally test the new application without using raw resources and modelling the use of ecologically compatible materials; saving working times and only then if the simulation is useful [19, 20].The current study summarises notable research publications on DT-based systems and technology, which uses the SLR technique as the primary instrument for a meta-analysis on SLR. The language that will be used to conduct research in various databases has been determined. This article provides a meta-SLR that allows us to notice and debate the major classes of needs that must be considered in sustainable DT development, also highlighting gaps and limitations in research and practise.This paper is structured accordingly: Section2 provides the following SLR technique; Section 3 gives the meta-SLR findings; Section 4 presents a critical analysis to suggest future work routes. Finally, the major findings of Section 5 are presented.


## 2. Methodology for Research

In developing this study, we examined Kitchenhand et al.’s approach for program architecture, and then we looked at the work of Escalon and Aldean, since they provided a technique that is useful in this work [21, 22]. The SLR technique developed includes three major stages: a planning phase, the execution of this plan and an analysis of the outcomes. The starting phase includes projects: (i) extracting studies from databases, (ii) removing copies from the tests, (iii) applying criteria for inclusion and exclusion, and (iv) collecting backward and forward citations, and (v) determining the end of the chosen article information sets. If fresh documents have been discovered at task IV, then the researcher reverses to task (ii) and continues the procedure as often as necessary, from task (ii) to task (iv). Additionally, we have also incorporated the backward and forward citation procedures in its selection phase [26], reported by Wolfs Winkel et al. If there is no research job in the presently chosen collection, it is deemed tenable; it should be added to those selected. Because it is a highly popular tool that enables retrospective and forward survey of citations, it is the primary tool. The entire procedure is shown Figure 1, influenced by Escalon and Aldean methodology [23].Figure 1
SLR's overall procedure (in BPMN notation).In order to make our study more accurate, examined the trial. They specifically indicated and classified the various kinds of accessible regulated or common vocabulary and the use of software development criteria, which were essential since we wanted to concentrate on establishing sustainability needs [24, 25]. It aims to arrange information consistently in a structured way that identifies semantical connections and allows for the easy categorization, query, and retrieval of information. The most common controlled vocabularies (CVs) are ontology, taxonomy, thesaurus, and folksonomy. Natural language processing and knowledge management often utilize tools for CV assistance [26].


### 2.1. Phase of Planning

The design phase is the component in which the SLR is carried out in agreement with the chosen scheme. The connection between sustainability needs and DT systems is addressed, followed by the establishment of relationships to product design. It outlines the key issues that drove this study; sections deal with scientific repositories and search queries as well as the criteria of inclusion and exclusion [27, 28].


#### 2.1.1. Analysis of Study

We have explained survey issue (RQ1) with three sections (SQ). These queries were used to meet the major study goals:(1)
Which is the state of the art in the field of DT-based products design sustainability requirements?(2)
Which is the connection between DTs and output style?(3)
SQ2 : what are the criteria of DTs for environmental sustainability?(4)
SQ3 : what are outstanding questions and difficulties in future DT and sustainability research paths?The search method takes account of these issues, network explanation accessible in the current literature and the following reading of the discovered work is also necessary.


#### 2.1.2. Search Process

The following were the scientific information bases or repositories which searched for suitable documents to address the queries of this study. The information bases were chosen since they are widely known to the scientific class and have also been utilised in previous SLR studies which we regarded to be IT domain models:(1)
ACM Electronic Library [dl.acm.org](2)
Taylor and Francis (http://www.tandfonline.com, 4 June 2021 accessed)(3)
Science web (http://www.webofknowledge.com)(4)
ScienceDirect/Scopus (http://www.scopus.com, 4 June 2021)(5)
Exploration of IEEE (i.e., explorer. Search/advanced)(6)
Elsevier (http://www.elsevier.com)(7)
Google ScholarThese were the conditions for inclusion: (i) article written during the last period; (ii) work written in journals and in conference papers or indexed books; (iii) work written in English; (iv) SLR papers chosen in the initial research database. They were brief oppositely, these were the conditions of exclusion: (i) extremely brief (i.e., less than 6 pages) publications and (ii) repeated works united with the information base under different reference [29, 30].


#### 2.1.3. Requests

In the first week of January 2021, we began the question “orderly survey of the literature” AND “electronic copy” (all areas) and then tried out various inquiries, not only considering the primary goal of this paper but also the articles we discovered and the potential to deepen our search. The initial work was to look for documents about a DT meta-SLR, and the second was to find sustainable criteria [31, 32]. The survey period was also examined, firstly, the dates of publishing between 1 January 2011 and 31 January 2020, and secondly, the dates of publication between 01/01/2009 and 31 December 2020. As a result, many other inquiries have been utilised:(1)
[All: “systematic evaluation of literature”] AND [All: “Expectations”] YEAR [All: 'digital twin∗ ’] AND (“Document title”: “Digi table twin” • IEEE) : AND (“All metadata”: ALL Metadata”: ALL Metadata Review); and (“All Metadata”: ALL Metadata Review”) AND (“ALL Metadata”: DESIGN”). ALL Metadata (“ALL DOCK Title”: ALL Metainformation”);(2)
(systematic review of literatures) and Name-ABS-KEY (systematic review of literature) AND (“ontology” and “electronic copy”); SCOPUS (systematic literary review).(3)
Science Web: [“electronic copy”] AND [All: “systematic review of literature”] [All: “product design”] AND TICK: (systematic review of literature “electronic copy∗ ”) and TITLE: (systematic reviews of literature AND “ontology ∗ ”).We have produced different scientific results in various databases and thus have had to utilise alternative searches. The keyword search for “milieu tenability” was unsuccessful.


### 2.2. Phase of Execution

The execution stage is the work in which both the findings and the execution of the SLR are described. We have followed the previously stated stages and criteria and will explain our experience and the valuable information we were able to collect throughout this procedure. The questions were given in the above information bases, and the output is shown [33, 34]. After we received the findings from these databases, the following procedures have been completed. The first is to remove duplicates; secondly, if barring criteria apply based on the titles; thirdly, on the basis of the titles, to pick articles where the criteria of inclusion and exclusion does not mention, for left out paper, examine the name section and reread steps 2 to 4; sixthly, Google Scholar will check the forward quotations for each appropriate reference and reread steps 2 to 4 for each remaining article [35].A first search (see Table1’s column on “First search”) enabled us to find works, and a second search allowed Google Scholar to identify citations (see Google Scholar columns). Relevant articles may be identified to evaluate the factors of DT use even if they are not SLRs (see column “non-SLR”). Finally, it was able to choose 29 articles, (“Selected Papers” column, including papers), to view abstracts from the papers [36, 37]. Table 2 lists SLR papers, while Table 3 lists non-SLR papers. The documents in question are article, T-these and B-Book. The SLR articles selected are relatively recent: 2020 (10 documents); 2019 (2 documents) and 2018 (18 documents).Table 1
Survey in information bases.
Data baseSurveyWith Google ScholarSLRNon-SLRACM6.215.43.17.3Elsevier19.510.21.22.1IEEE Explore13.134.61.24.2Scopus12.0143.44.11.1Tailor4.0241.22.12.2Web Science7.0516.022.20.1Total61.01159.0113.116.1Table 2
Chosen SLR papers.
Serial noReferenceNameYearTopic1[1]Electronic copy characterization: a Comprehensive art survey.2019DTs definition2[2]Digital twin review on ideas, technology, and trade programs.2019DTs definition3[3]Cyber security prediction electronic copy: multivocal study2020DTs cyber security4[4]Cyber-physical systems reference framework for digital twins2020DTs cyber practical systems5[10]Evaluation of connections between rounded financial and trade 4.0: a Comprehensive study of art2020DTs, CE, 14.056[33]Sustainability influence of trade 4.0 - review of library literature2019DTs 14.057[34]Industry 4.0 rounded financial copy and cleaner manufacturing2020DTs, CE 14.08[35]Digital twin systems: Cosmology and contextual framework2019DTs outlook9[36]A study of the active trade implementation art2019DTs,14.0510[37]Digital twins: Smart City's current challenges and future technological recommendations2018DTs smart city11[38]Electronic copy process of steel sawing2020DTs. Example12[39]A systemic art study on ontology software in auto application2019DTs ontology13[40]The double electronic trade context-a study and systems review2019DTsTable 3
Chosen non-slr papers.
IdReferencesTitleyearsKindSubjectNS1[8]Improving experimental act and output boons via the use of intelligent brewing technology2019J14.0NS2[41]An assessment of the potential trade to speed the transition to a rounded finance2020T14.0, CENS3[42]Energy cyber-physical system IoT-based digital twin: style and practice2018cDTs, energyNS4[43]A quantifying power and outlook boons framework for intelligent production technology2019C14.0, powerNS5[44]Creating electronic copy' data resources2019jDTs, dataNS6[45]On IoT intensive electronic copy application system engineering2018jDTs, IOTNS7[46]Electronic copy-depends upon health application style-a new medical/medical software development approach2019jDTs eHealthNS8[47]Digital twins taxonomy2019CDTsNS9[48]Define structure needs for electronic copy2020TDTs needsNS1O[49]Development of a structure for digital scoping of twins in the procedure trade2020JDT’s structureNS11[50]An agenda new da gran industries: Uma analyse da industries [4], con base elm documents e matters de divulgence do projector alma industrial platform +4.02020T14.0NS12[51]The modernization of the archives in order to provide support to transforaminal electronic2020COrganizationNS13[52]To the operationalisation of the methodology of socio-technical engineering2019JOutlookNS14[53]Ontology applications in requirements engineering: a Comprehensive literature review2019JOutlookNS15[54]Fusing practical and electronic copy in the practise of rounded economics:2016CDTs, CENS16[55]Specification study of application needs using natural words procedure method.2013JNeeds(1 document) The same goes to chosen documents: 2020 (12 documents); 2019 (2 papers); 2016 (1 paper); 2013 (2 papers) (1 paper). This is hardly unexpected since the technology and problems examined are relatively recent as shown in Figure2.Figure 2
Existing work on digital twin.


## 2.1. Phase of Planning

The design phase is the component in which the SLR is carried out in agreement with the chosen scheme. The connection between sustainability needs and DT systems is addressed, followed by the establishment of relationships to product design. It outlines the key issues that drove this study; sections deal with scientific repositories and search queries as well as the criteria of inclusion and exclusion [27, 28].


### 2.1.1. Analysis of Study

We have explained survey issue (RQ1) with three sections (SQ). These queries were used to meet the major study goals:(1)
Which is the state of the art in the field of DT-based products design sustainability requirements?(2)
Which is the connection between DTs and output style?(3)
SQ2 : what are the criteria of DTs for environmental sustainability?(4)
SQ3 : what are outstanding questions and difficulties in future DT and sustainability research paths?The search method takes account of these issues, network explanation accessible in the current literature and the following reading of the discovered work is also necessary.


### 2.1.2. Search Process

The following were the scientific information bases or repositories which searched for suitable documents to address the queries of this study. The information bases were chosen since they are widely known to the scientific class and have also been utilised in previous SLR studies which we regarded to be IT domain models:(1)
ACM Electronic Library [dl.acm.org](2)
Taylor and Francis (http://www.tandfonline.com, 4 June 2021 accessed)(3)
Science web (http://www.webofknowledge.com)(4)
ScienceDirect/Scopus (http://www.scopus.com, 4 June 2021)(5)
Exploration of IEEE (i.e., explorer. Search/advanced)(6)
Elsevier (http://www.elsevier.com)(7)
Google ScholarThese were the conditions for inclusion: (i) article written during the last period; (ii) work written in journals and in conference papers or indexed books; (iii) work written in English; (iv) SLR papers chosen in the initial research database. They were brief oppositely, these were the conditions of exclusion: (i) extremely brief (i.e., less than 6 pages) publications and (ii) repeated works united with the information base under different reference [29, 30].


### 2.1.3. Requests

In the first week of January 2021, we began the question “orderly survey of the literature” AND “electronic copy” (all areas) and then tried out various inquiries, not only considering the primary goal of this paper but also the articles we discovered and the potential to deepen our search. The initial work was to look for documents about a DT meta-SLR, and the second was to find sustainable criteria [31, 32]. The survey period was also examined, firstly, the dates of publishing between 1 January 2011 and 31 January 2020, and secondly, the dates of publication between 01/01/2009 and 31 December 2020. As a result, many other inquiries have been utilised:(1)
[All: “systematic evaluation of literature”] AND [All: “Expectations”] YEAR [All: 'digital twin∗ ’] AND (“Document title”: “Digi table twin” • IEEE) : AND (“All metadata”: ALL Metadata”: ALL Metadata Review); and (“All Metadata”: ALL Metadata Review”) AND (“ALL Metadata”: DESIGN”). ALL Metadata (“ALL DOCK Title”: ALL Metainformation”);(2)
(systematic review of literatures) and Name-ABS-KEY (systematic review of literature) AND (“ontology” and “electronic copy”); SCOPUS (systematic literary review).(3)
Science Web: [“electronic copy”] AND [All: “systematic review of literature”] [All: “product design”] AND TICK: (systematic review of literature “electronic copy∗ ”) and TITLE: (systematic reviews of literature AND “ontology ∗ ”).We have produced different scientific results in various databases and thus have had to utilise alternative searches. The keyword search for “milieu tenability” was unsuccessful.


## 2.1.1. Analysis of Study

We have explained survey issue (RQ1) with three sections (SQ). These queries were used to meet the major study goals:(1)
Which is the state of the art in the field of DT-based products design sustainability requirements?(2)
Which is the connection between DTs and output style?(3)
SQ2 : what are the criteria of DTs for environmental sustainability?(4)
SQ3 : what are outstanding questions and difficulties in future DT and sustainability research paths?The search method takes account of these issues, network explanation accessible in the current literature and the following reading of the discovered work is also necessary.


## 2.1.2. Search Process

The following were the scientific information bases or repositories which searched for suitable documents to address the queries of this study. The information bases were chosen since they are widely known to the scientific class and have also been utilised in previous SLR studies which we regarded to be IT domain models:(1)
ACM Electronic Library [dl.acm.org](2)
Taylor and Francis (http://www.tandfonline.com, 4 June 2021 accessed)(3)
Science web (http://www.webofknowledge.com)(4)
ScienceDirect/Scopus (http://www.scopus.com, 4 June 2021)(5)
Exploration of IEEE (i.e., explorer. Search/advanced)(6)
Elsevier (http://www.elsevier.com)(7)
Google ScholarThese were the conditions for inclusion: (i) article written during the last period; (ii) work written in journals and in conference papers or indexed books; (iii) work written in English; (iv) SLR papers chosen in the initial research database. They were brief oppositely, these were the conditions of exclusion: (i) extremely brief (i.e., less than 6 pages) publications and (ii) repeated works united with the information base under different reference [29, 30].


## 2.1.3. Requests

In the first week of January 2021, we began the question “orderly survey of the literature” AND “electronic copy” (all areas) and then tried out various inquiries, not only considering the primary goal of this paper but also the articles we discovered and the potential to deepen our search. The initial work was to look for documents about a DT meta-SLR, and the second was to find sustainable criteria [31, 32]. The survey period was also examined, firstly, the dates of publishing between 1 January 2011 and 31 January 2020, and secondly, the dates of publication between 01/01/2009 and 31 December 2020. As a result, many other inquiries have been utilised:(1)
[All: “systematic evaluation of literature”] AND [All: “Expectations”] YEAR [All: 'digital twin∗ ’] AND (“Document title”: “Digi table twin” • IEEE) : AND (“All metadata”: ALL Metadata”: ALL Metadata Review); and (“All Metadata”: ALL Metadata Review”) AND (“ALL Metadata”: DESIGN”). ALL Metadata (“ALL DOCK Title”: ALL Metainformation”);(2)
(systematic review of literatures) and Name-ABS-KEY (systematic review of literature) AND (“ontology” and “electronic copy”); SCOPUS (systematic literary review).(3)
Science Web: [“electronic copy”] AND [All: “systematic review of literature”] [All: “product design”] AND TICK: (systematic review of literature “electronic copy∗ ”) and TITLE: (systematic reviews of literature AND “ontology ∗ ”).We have produced different scientific results in various databases and thus have had to utilise alternative searches. The keyword search for “milieu tenability” was unsuccessful.


## 2.2. Phase of Execution

The execution stage is the work in which both the findings and the execution of the SLR are described. We have followed the previously stated stages and criteria and will explain our experience and the valuable information we were able to collect throughout this procedure. The questions were given in the above information bases, and the output is shown [33, 34]. After we received the findings from these databases, the following procedures have been completed. The first is to remove duplicates; secondly, if barring criteria apply based on the titles; thirdly, on the basis of the titles, to pick articles where the criteria of inclusion and exclusion does not mention, for left out paper, examine the name section and reread steps 2 to 4; sixthly, Google Scholar will check the forward quotations for each appropriate reference and reread steps 2 to 4 for each remaining article [35].A first search (see Table1’s column on “First search”) enabled us to find works, and a second search allowed Google Scholar to identify citations (see Google Scholar columns). Relevant articles may be identified to evaluate the factors of DT use even if they are not SLRs (see column “non-SLR”). Finally, it was able to choose 29 articles, (“Selected Papers” column, including papers), to view abstracts from the papers [36, 37]. Table 2 lists SLR papers, while Table 3 lists non-SLR papers. The documents in question are article, T-these and B-Book. The SLR articles selected are relatively recent: 2020 (10 documents); 2019 (2 documents) and 2018 (18 documents).Table 1
Survey in information bases.
Data baseSurveyWith Google ScholarSLRNon-SLRACM6.215.43.17.3Elsevier19.510.21.22.1IEEE Explore13.134.61.24.2Scopus12.0143.44.11.1Tailor4.0241.22.12.2Web Science7.0516.022.20.1Total61.01159.0113.116.1Table 2
Chosen SLR papers.
Serial noReferenceNameYearTopic1[1]Electronic copy characterization: a Comprehensive art survey.2019DTs definition2[2]Digital twin review on ideas, technology, and trade programs.2019DTs definition3[3]Cyber security prediction electronic copy: multivocal study2020DTs cyber security4[4]Cyber-physical systems reference framework for digital twins2020DTs cyber practical systems5[10]Evaluation of connections between rounded financial and trade 4.0: a Comprehensive study of art2020DTs, CE, 14.056[33]Sustainability influence of trade 4.0 - review of library literature2019DTs 14.057[34]Industry 4.0 rounded financial copy and cleaner manufacturing2020DTs, CE 14.08[35]Digital twin systems: Cosmology and contextual framework2019DTs outlook9[36]A study of the active trade implementation art2019DTs,14.0510[37]Digital twins: Smart City's current challenges and future technological recommendations2018DTs smart city11[38]Electronic copy process of steel sawing2020DTs. Example12[39]A systemic art study on ontology software in auto application2019DTs ontology13[40]The double electronic trade context-a study and systems review2019DTsTable 3
Chosen non-slr papers.
IdReferencesTitleyearsKindSubjectNS1[8]Improving experimental act and output boons via the use of intelligent brewing technology2019J14.0NS2[41]An assessment of the potential trade to speed the transition to a rounded finance2020T14.0, CENS3[42]Energy cyber-physical system IoT-based digital twin: style and practice2018cDTs, energyNS4[43]A quantifying power and outlook boons framework for intelligent production technology2019C14.0, powerNS5[44]Creating electronic copy' data resources2019jDTs, dataNS6[45]On IoT intensive electronic copy application system engineering2018jDTs, IOTNS7[46]Electronic copy-depends upon health application style-a new medical/medical software development approach2019jDTs eHealthNS8[47]Digital twins taxonomy2019CDTsNS9[48]Define structure needs for electronic copy2020TDTs needsNS1O[49]Development of a structure for digital scoping of twins in the procedure trade2020JDT’s structureNS11[50]An agenda new da gran industries: Uma analyse da industries [4], con base elm documents e matters de divulgence do projector alma industrial platform +4.02020T14.0NS12[51]The modernization of the archives in order to provide support to transforaminal electronic2020COrganizationNS13[52]To the operationalisation of the methodology of socio-technical engineering2019JOutlookNS14[53]Ontology applications in requirements engineering: a Comprehensive literature review2019JOutlookNS15[54]Fusing practical and electronic copy in the practise of rounded economics:2016CDTs, CENS16[55]Specification study of application needs using natural words procedure method.2013JNeeds(1 document) The same goes to chosen documents: 2020 (12 documents); 2019 (2 papers); 2016 (1 paper); 2013 (2 papers) (1 paper). This is hardly unexpected since the technology and problems examined are relatively recent as shown in Figure2.Figure 2
Existing work on digital twin.


## 3. Survey of the Literature and Output

This part contains documents related to (i) determination of needs for sustainability and (ii) recognition of the connection between DTs and the design of the product. The two dimensions permitted to map the responses we consider. Papers were classified according to the two dimensions, which in each study were chosen by the dominating work [38, 39].


### 3.1. Sustainability and Digital Twins Requirements

There are four articles and 4 non-SLR papers among our chosen papers, primarily relating to DTs and sustainability. In addition, the definitions “state of the art” on DT development is examined by Pokharel, (S3) including the noted paper of the utility of DT for cybersecurity using the SRL approach. In terms of event predictions, the situations in which are used include oddity detection; distant and monitoring; practical monitoring; predictive study; documentation; and communication. Safety is one important aspect of tenability; if equipment is hazardous, its everyday use is impossible.


### 3.2. SLR Application

The SLR technique is used to evaluate the connection between CE and I4.0. They emphasise hybrid categories such as rounded I4.0 and digital EC, but continue to identify the key boons and integration, like technology, economic act, market growth, supply chain management, product life-cycle management, employee power, and business patterns40, 41, 56.Esmond, Gladys, and Kleczka (S6) conduct a literature analysis to assess the sustainability effect of trade. They discover that CE writers often also research tenable produce chains, but themes, such as tenability, huge information, smart production, IoT, tenable progress, electronic change, and trade IoT, are often mentioned [42]. Also, prevalent ideas include internet-practical systems, sustainable production, the smart factory, and digitisation. The major conclusion of their study is may be that the good result of these technologies in terms of sustainability is not guaranteed, which means success needs encouraging measures and particular regulations to maintain the competitiveness of local players [43, 44].Rajput and Singh (S7) propose a CE and cleaner Industry 4.0 models. Its approach is based on linear programming with mixed-integer (MILP) to optimise the allocation of the machine's production, for example, to optimise the trade in power consumption and processing costs [45]. This model uses sensors to collect practical-period data in trade emphasises the difficulty of the new I4.0 and its related new technologies, e.g., 3D printing, to optimise production. Since no generation minus energy (meaning at trade level electricity, nonuseable sources of energy are still the most important contributor to power production), the next three papers examine the general need of “energy responsibly.” Spear et al. [43] (NS4) provide a methodology for quantification of the advantages of smart manufacturing technology in terms of energy and productivity [46].The example of this framework and the use of intelligent production technology are also explained. The framework utilises CCE (energy conservation cost) as a supplementary metric to evaluate the viability of a series of intelligent manufacturing actions. The emphasis is on the measurement and analysis of energy productivity and a strategic analytical frame has been created to predict cost-effective energy and productivity gains utilising smart production [47, 48].Saad, Fadel and Mohammed (NS3) are studying the efficient and effective application of DTs in cyber-physical energy systems. With distributed energy resources (DERs), communications and controlling complexity, it is essential to provide an effective platform capable of digesting all incoming data and ensuring a dependable power system operation. Two different DT-types have been developed to construct this support technology: one for huge bandwidth applications and one for less bandwidth applications which need centralised surveillance decision-making [49, 50].


### 3.3. Electronic Copy and the Style of Products

The following documents are essential for a platform between DTs and product design. These articles present and evaluate issues which should be considered in actual situations while developing or constructing DTs: attempt to define the notion of DT using an SLR. The writers recognise that a range of definitions are used across business and the universities [51].They identified thirteen features to explain the definition, namely practical/dual, virtual/dual, physical environment, virtual environment, state, metrology, twinning, twinning speed, virtual-to-virtual connection/twinning, practical process, and a whole structure and operating process of the DT [52, 53]. Literature overview of the DT based on ideas, technology and industrial applications is provided by Liu et al. (S2). They assess the present situation of the art, explain the idea of the DT, and examine several important DT enabling technologies. Furthermore, they describe 15 trade software's with their distinct life cycles, important insights and further work suggestions. Kosovska, Jigidas, and Engels (S4) are developing a DTs Reference Framework in internet-practical systems (CPSs). The writes describe CPS (characters per second) system representations that combine physical devices and processes via the Internet with computational entities that enable omnipresent research for data and duties. The framework creates a connection between the CPS architecture of 5 levels and the DT framework in order to address outstanding issues and difficulties about style and implement CPSs. Barth et al. (S8) systematises the DTs and creates a philosophical and ontological framework. In addition, the authors attempt to address three questions from the research: (i) what are the parameters for classifying and structuring DT in study literature? (ii) In these dimensions, what are the basic distinctions or specifications? And, (iii) how do the various requirements connect to one other? Bohemia and Rub (S9) explain to grasp the realities of the installation of a smart plant utilising and SLR. They highlight a research gap associated with the choice to manufacture or purchase DTs and other key components of the smart factory. This is important since the smart factory is expected to lead to value creation, but this creation relies on how the facility is built, whether the project is done internally or utilising an external provider. Dave et al. (S10) explore the potential new reality of intelligent cities, where the latter's roles are highlighted by ideas like Big Data, Robotics, and DTs. The primary applications for DTs are smart cities, manufacturing, and healthcare. An example of how DT is used is its use in traffic management systems, employing traffic cameras that just record, but their recordings may be used to build traffic management models that help decrease traffic congestion and give more information to export and update the road network in real time. The authors suggest that demonstration sites are needed to evaluate real-life data in the new technologies and a need for broad expert panels in a variety of areas such as urban planning, IT, transportation, and environmental regulations. The DT example for the stone-sawing process is Pollini and Corrido (S11). The writer explains the DT but have reservations about the accuracy and efficiency of the apparatus. Reference [39] (S12) are using an SLR for studying potential usage of cosmology in automated programming. Ontologies that are usually regarded as technical or an artefact in one or more life cycle stages of software may be utilised to assist accomplish this. The objective of discovering greater levels of abstraction and methods to utilise application to improve its productivity and quality within the software engineering field. Jarod et al. (S3) are systematically studying the DT idea in the industry. Since 2015, the authors recognise a substantial increase in the quantity of scientific research (industry-related publications with the title “Digital Twin”). Studies demonstrate a range of DT applications from goods and processes to whole production systems [54, 55]. Explicit descriptions are somewhat contradictory, and related concepts like “Avatar product” and “Digital Shadow” have also been discovered. Their study broadened the theory and laid the groundwork further, better DT modelling and Mayrhofer (NS5) are working on data resources to generate DTs [56]. For companies transitioning from the production of products to the provision of services, DTs are regarded one of the essential technologies. The primary premise is that most of the new data or resources created while the start of phase of a product life cycle is not utilised in the middle of life (MOL). The new framework provides a better knowledge of how to utilise BOL data resources in MOL stages and enables the development of ontology of product data which facilitates DT generation and maintenance. NS6 is examining the engineering of IoT-intensive DT software systems carefully. The authors believe that the actual DT is a product equipped with several sensors or computer systems, which generates, consumes, and transfers data for diverse reasons. Because of this fact, DTs are often regarded as IoT-intensive systems. Lutze (NS7) is investigating eHealth's software design as a novel way to healthcare/medical product development. The DT idea of the writer makes on (i) personal digital twin as a patient's wife, (ii) a digital twin group that models the software's intended user group, and (iii) an electronic copy system for the product itself. Agile development methods are believed to provide greater assistance in contrast to the classical software development based on the V-model, several aspects of DTs are identified: data connection, motive, conceptual components, interface, synchronisation, data input, and time generation. Jay (NS9) outlines the needs of infrastructure to create DTs. The author also expects that simulation is a fundamental system feature after 2015 with seamless support throughout its whole wheel of life, supporting the experiments and the service via a direct connection to operating data. Peron and Ham study manufacturing processes, and in that, setting they create a paradigm for DT scoping. Due to the uniqueness of the idea and the wide spectrum of technology it builds on, the digital scope processes.For process businesses, dual projects may be intimidating. It attributes the new “Platform Industries 4.0″ initiative to its consequences. After a short description of its technology, (i) how existing legacy systems can be decentralised to deliver a technology solution which responds to a new user need electronic class and (ii)build a system architecture which displays the features of electronic change. Senses et al. (NS13) utilise SLR to find qualitative online engineering research. These writers' primary objective is to operationalize the socio-technical ontology approach.Dermal [53] (NS14) utilises SLR to detect RE ontological applications (requirements architecture). The important survey of this study are (i) empirical evidence of the benefits of using ontology in RE activities is available, particularly to reduce ambiguity and incompleteness; (ii) the procedure usually is only partially dealt with, for example, only taking functional requirements into consideration; (iii) ontologies support large-scale RE modelling styles; Tools for supporting various types of RE ontology-driven approaches have been used/developed; (v) half the studies have followed recommendations on ontology-driven languages; (vi) large diversity of RE ontologies have been noticed; nevertheless; (vii) many promising research opportunities have been noticed. Other writers also provide important contribution for this debate. Rocca et al. (NS15) are trying to use VR, DT, and CE basketwork techniques and provide a scenario for laboratory applications: virtually test waste from the disassembler plant setup (WEEE) by utilising a sec of specialised simulation instruments. The authors highlight the significance of their work, owing to a growing consumer knowledge of climate change impacts, high demand instability in many industries, and the rapid simulation and digitisation of production processes. Fasano [55] (NS16) is proposing a software specification analysis utilising processing methods in the natural language. The author attempts to enhance the manufacturing process of the software product.


## 3.1. Sustainability and Digital Twins Requirements

There are four articles and 4 non-SLR papers among our chosen papers, primarily relating to DTs and sustainability. In addition, the definitions “state of the art” on DT development is examined by Pokharel, (S3) including the noted paper of the utility of DT for cybersecurity using the SRL approach. In terms of event predictions, the situations in which are used include oddity detection; distant and monitoring; practical monitoring; predictive study; documentation; and communication. Safety is one important aspect of tenability; if equipment is hazardous, its everyday use is impossible.


## 3.2. SLR Application

The SLR technique is used to evaluate the connection between CE and I4.0. They emphasise hybrid categories such as rounded I4.0 and digital EC, but continue to identify the key boons and integration, like technology, economic act, market growth, supply chain management, product life-cycle management, employee power, and business patterns40, 41, 56.Esmond, Gladys, and Kleczka (S6) conduct a literature analysis to assess the sustainability effect of trade. They discover that CE writers often also research tenable produce chains, but themes, such as tenability, huge information, smart production, IoT, tenable progress, electronic change, and trade IoT, are often mentioned [42]. Also, prevalent ideas include internet-practical systems, sustainable production, the smart factory, and digitisation. The major conclusion of their study is may be that the good result of these technologies in terms of sustainability is not guaranteed, which means success needs encouraging measures and particular regulations to maintain the competitiveness of local players [43, 44].Rajput and Singh (S7) propose a CE and cleaner Industry 4.0 models. Its approach is based on linear programming with mixed-integer (MILP) to optimise the allocation of the machine's production, for example, to optimise the trade in power consumption and processing costs [45]. This model uses sensors to collect practical-period data in trade emphasises the difficulty of the new I4.0 and its related new technologies, e.g., 3D printing, to optimise production. Since no generation minus energy (meaning at trade level electricity, nonuseable sources of energy are still the most important contributor to power production), the next three papers examine the general need of “energy responsibly.” Spear et al. [43] (NS4) provide a methodology for quantification of the advantages of smart manufacturing technology in terms of energy and productivity [46].The example of this framework and the use of intelligent production technology are also explained. The framework utilises CCE (energy conservation cost) as a supplementary metric to evaluate the viability of a series of intelligent manufacturing actions. The emphasis is on the measurement and analysis of energy productivity and a strategic analytical frame has been created to predict cost-effective energy and productivity gains utilising smart production [47, 48].Saad, Fadel and Mohammed (NS3) are studying the efficient and effective application of DTs in cyber-physical energy systems. With distributed energy resources (DERs), communications and controlling complexity, it is essential to provide an effective platform capable of digesting all incoming data and ensuring a dependable power system operation. Two different DT-types have been developed to construct this support technology: one for huge bandwidth applications and one for less bandwidth applications which need centralised surveillance decision-making [49, 50].


## 3.3. Electronic Copy and the Style of Products

The following documents are essential for a platform between DTs and product design. These articles present and evaluate issues which should be considered in actual situations while developing or constructing DTs: attempt to define the notion of DT using an SLR. The writers recognise that a range of definitions are used across business and the universities [51].They identified thirteen features to explain the definition, namely practical/dual, virtual/dual, physical environment, virtual environment, state, metrology, twinning, twinning speed, virtual-to-virtual connection/twinning, practical process, and a whole structure and operating process of the DT [52, 53]. Literature overview of the DT based on ideas, technology and industrial applications is provided by Liu et al. (S2). They assess the present situation of the art, explain the idea of the DT, and examine several important DT enabling technologies. Furthermore, they describe 15 trade software's with their distinct life cycles, important insights and further work suggestions. Kosovska, Jigidas, and Engels (S4) are developing a DTs Reference Framework in internet-practical systems (CPSs). The writes describe CPS (characters per second) system representations that combine physical devices and processes via the Internet with computational entities that enable omnipresent research for data and duties. The framework creates a connection between the CPS architecture of 5 levels and the DT framework in order to address outstanding issues and difficulties about style and implement CPSs. Barth et al. (S8) systematises the DTs and creates a philosophical and ontological framework. In addition, the authors attempt to address three questions from the research: (i) what are the parameters for classifying and structuring DT in study literature? (ii) In these dimensions, what are the basic distinctions or specifications? And, (iii) how do the various requirements connect to one other? Bohemia and Rub (S9) explain to grasp the realities of the installation of a smart plant utilising and SLR. They highlight a research gap associated with the choice to manufacture or purchase DTs and other key components of the smart factory. This is important since the smart factory is expected to lead to value creation, but this creation relies on how the facility is built, whether the project is done internally or utilising an external provider. Dave et al. (S10) explore the potential new reality of intelligent cities, where the latter's roles are highlighted by ideas like Big Data, Robotics, and DTs. The primary applications for DTs are smart cities, manufacturing, and healthcare. An example of how DT is used is its use in traffic management systems, employing traffic cameras that just record, but their recordings may be used to build traffic management models that help decrease traffic congestion and give more information to export and update the road network in real time. The authors suggest that demonstration sites are needed to evaluate real-life data in the new technologies and a need for broad expert panels in a variety of areas such as urban planning, IT, transportation, and environmental regulations. The DT example for the stone-sawing process is Pollini and Corrido (S11). The writer explains the DT but have reservations about the accuracy and efficiency of the apparatus. Reference [39] (S12) are using an SLR for studying potential usage of cosmology in automated programming. Ontologies that are usually regarded as technical or an artefact in one or more life cycle stages of software may be utilised to assist accomplish this. The objective of discovering greater levels of abstraction and methods to utilise application to improve its productivity and quality within the software engineering field. Jarod et al. (S3) are systematically studying the DT idea in the industry. Since 2015, the authors recognise a substantial increase in the quantity of scientific research (industry-related publications with the title “Digital Twin”). Studies demonstrate a range of DT applications from goods and processes to whole production systems [54, 55]. Explicit descriptions are somewhat contradictory, and related concepts like “Avatar product” and “Digital Shadow” have also been discovered. Their study broadened the theory and laid the groundwork further, better DT modelling and Mayrhofer (NS5) are working on data resources to generate DTs [56]. For companies transitioning from the production of products to the provision of services, DTs are regarded one of the essential technologies. The primary premise is that most of the new data or resources created while the start of phase of a product life cycle is not utilised in the middle of life (MOL). The new framework provides a better knowledge of how to utilise BOL data resources in MOL stages and enables the development of ontology of product data which facilitates DT generation and maintenance. NS6 is examining the engineering of IoT-intensive DT software systems carefully. The authors believe that the actual DT is a product equipped with several sensors or computer systems, which generates, consumes, and transfers data for diverse reasons. Because of this fact, DTs are often regarded as IoT-intensive systems. Lutze (NS7) is investigating eHealth's software design as a novel way to healthcare/medical product development. The DT idea of the writer makes on (i) personal digital twin as a patient's wife, (ii) a digital twin group that models the software's intended user group, and (iii) an electronic copy system for the product itself. Agile development methods are believed to provide greater assistance in contrast to the classical software development based on the V-model, several aspects of DTs are identified: data connection, motive, conceptual components, interface, synchronisation, data input, and time generation. Jay (NS9) outlines the needs of infrastructure to create DTs. The author also expects that simulation is a fundamental system feature after 2015 with seamless support throughout its whole wheel of life, supporting the experiments and the service via a direct connection to operating data. Peron and Ham study manufacturing processes, and in that, setting they create a paradigm for DT scoping. Due to the uniqueness of the idea and the wide spectrum of technology it builds on, the digital scope processes.For process businesses, dual projects may be intimidating. It attributes the new “Platform Industries 4.0″ initiative to its consequences. After a short description of its technology, (i) how existing legacy systems can be decentralised to deliver a technology solution which responds to a new user need electronic class and (ii)build a system architecture which displays the features of electronic change. Senses et al. (NS13) utilise SLR to find qualitative online engineering research. These writers' primary objective is to operationalize the socio-technical ontology approach.Dermal [53] (NS14) utilises SLR to detect RE ontological applications (requirements architecture). The important survey of this study are (i) empirical evidence of the benefits of using ontology in RE activities is available, particularly to reduce ambiguity and incompleteness; (ii) the procedure usually is only partially dealt with, for example, only taking functional requirements into consideration; (iii) ontologies support large-scale RE modelling styles; Tools for supporting various types of RE ontology-driven approaches have been used/developed; (v) half the studies have followed recommendations on ontology-driven languages; (vi) large diversity of RE ontologies have been noticed; nevertheless; (vii) many promising research opportunities have been noticed. Other writers also provide important contribution for this debate. Rocca et al. (NS15) are trying to use VR, DT, and CE basketwork techniques and provide a scenario for laboratory applications: virtually test waste from the disassembler plant setup (WEEE) by utilising a sec of specialised simulation instruments. The authors highlight the significance of their work, owing to a growing consumer knowledge of climate change impacts, high demand instability in many industries, and the rapid simulation and digitisation of production processes. Fasano [55] (NS16) is proposing a software specification analysis utilising processing methods in the natural language. The author attempts to enhance the manufacturing process of the software product.


## 4. The Debate

The DT research is new, particularly after 2015, and the explanation of DT is ambiguous. However, irrespective of the ever-increasing complexity of their applications of DTs, such as industrial optimisation, and the sustainability of the product design process are agreed on. Furthermore, the absence of research with technical data may be difficult to use. A deeper examination of potential environmental sustainability advantages and product design may contribute to a visible grasp of the reality. Analysis of the literature available enables us to detect many elements of DT relationships, output style, and sustainability and, therefore, to reply to the real research question, we address the following subquestions (Qi):(1)
SQ1: how does DTs relate to product design? As for SQ1, from the chosen articles, we check that two connections with product design are mostly established: I DTs are digital goods fed with real-time data that play a vital role in understanding actual behaviours and adjustments required and (ii) DT testing are cheaper and simpler than creating latest practical copies.(2)
SQ2: what are the criteria of DT for environmental sustainability? About SQ2, the major environmental classes of sustainability criteria are based on the chosen literature: I (the management of energy use) the use of environmentally known matters. When CE is examined at I4.0, there is an obvious requirement a balance of and difficulty power consumption against the outcomes of the new application of technology. Perhaps the testing of DT and the creation of less complicated goods are the primary study issue.(3)
SQ3: what are the difficulties and risks in future DTs and sustainability research paths? As regards SQ3, the complexity reduction in building and installing DTs is just one route for future study in the first place and as previously stated. When the choice to deploy DTs at manufacturing level is considered the effect of complexity and energy consumption is crucial. This has an overall effect in terms of safety, environment, and financial sustainability on sustainability. The meta-SLR described enabled us to identify many outstanding research problems and difficulties. First, techniques and processes are required to develop and execute DTs. This should be taken into consideration because there are many application domains with their peculiarities. Although there are comprehensive explanations of DTs how to realise them is unclear, particularly if no prior experience is available. Secondly, SL R&D studies show gaps like: I the boons have not been discovered; (ii) DT is not adequately investigated life cycle or the DT life cycle (iii) It is unclear to contribute to cost reduction or improvements in service or supporting decision-making; (iv) technical implementation must be improved and detailed under IoT; (v) the loyalty standard is not assessed in terms of the number of parameters, their accuracy and levels of IoT As previously stated, DTs are a new technology, partly explaining these gaps or varied potential pathways to study.At the same time, the DT idea is being explicitly defined, such as the classification of current levels such as “Platform trade 4.0,” describing a standardised DT in the I4.0 [47]. If DTs are identified in various ways and situations, how can the most significant break in the study of sustainability in DT use be identified? We start with the premise that DT is made up of three elements: I a physical product, (ii) a virtual product and (iii) links and data that flow between them. Then, we presume that its primary contribution to sustainability may be identified at the technical implementation and at a certain degree of accuracy. RQ1: what is the state of the art in the field of DT-based products design sustainability requirements??Finally, we must deal with our initial research question RQ1. Despite the current limitations, the literature highlights certain sustainability criteria of DT-based product design systems: I loyalty; (ii) power management; (iii) complexity control; (iv) environmental and cost-effective material identification; and (v) simple replication of new product designs. Various researches examine different sustainability criteria and no comprehensive methodology is available to comprehend how DTs may promote environmental sustainability. For instance, a completely stringent fidelity requires extra period and further energy expenditure, and this output may produce a compromise that results in fleeting loyalty. This fluid fidelity implies that environmental costs remain external to output since assessment of these costs would likewise involve additional labour and expenses. Easy premanufacturing of new product designs may lead to a lower cost of the manufacturing level.


## 5. Findings

In the study, significant research paper on DT-based systems and technology may be identified utilising the SLR technique as the primary instrument for a meta-analysis on SLR. The selection of language used for research in various databases has been given consideration. Based on this study, the RQ1 and the SQ1, SQ2, and SQ3 subquestions may be answered. Five major issues must be addressed in developing a tenable:(i) Loyalty; (ii) power control; (iii) complexity control; (iv) environmental and economically efficient material identification; and (v) simple replication of new product designs. Furthermore, research topics relating to DTs may be identified: (i) investigate their idea and description1, 4, 35, 36, 40, 47; (ii) presenting instances 38, 56; and (iii) using SLR to analyse existing research and suggest future pathways for research [2, 10, 33, 37]. SLR research is also available. The study enables us to identify two major gaps in two potential directions of research. The first break is the lack of a comprehensive article that explains precisely what a DT is, with a rich and complete example that underlines the features of the hardware and the links between the practical and electronic dimensions may be constructed, developed, and maintained. This fact may be explained by the trade reluctance to divulge sensitive information that the school fulfils. Second, articles were found with tenability in software's and, moreover, recognise research that differentiate between various kinds of sustainability Environmental sustainability included. Moreover, we find documents where the link with the use of DTs is explicitly established in the context of Industry 4.0. However, a study could not be found that addresses the environmental sustainability SLR of DTs alone. Is this simply a matter of language, with CE equivalent to environmental tenability? We think the result is negative because CE, on the plant level, is still a laboratory idea, and the complexity implicit in its implementation may be of the utmost importance. In other words, in order to assess this hypothesis, the issue of whether CE is ecologically sustainable when management and technically difficult is so remarkable, a future investigation route may be a scenario in which a nil environmental impact product is designed.This article offers a (SLR) on the sustainability DT-based systems. Many articles on DT have also been chosen since they referenced the studied SLRs and were deemed to be significant for the objectives of this study. Selected and analysed for papers revealed so many flaws and challenges: the boons of are not clear; DTs throughout the result the wheel of life of the DTs is not adequately surveyed; DTs can contribute to cost reduction or to support decision-making is unclear; Internet practice should be improved and better integrated Moreover, it is not been feasible from our study to locate a publication which solely discusses DTs in relation with situational sustainability.In summary, this article provides the meta-SLR that allows us to notice and debate the major classes of needs to be considered in sustainable DT development, but that also highlight gaps and limits in research and practise. This study can be useful in designing a frame for developing sustainable systems that can be more reliable and feasible in future in understanding SLR better. The future scope with regard to the present study is to relate the summarized findings with the recent developments capable to cater the needs of future requirements in the field of optimal design for the metasystematic sustainability of digital double-form systems.



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*Source: 2423750-2021-11-30.xml*