**2.2 Descriptive analysis**

Within the frame of the descriptive and content analysis the following search was used in the Scopus: (TITLE-ABS-KEY ("green supply chain") AND TITLE-ABS-KEY (distribution) AND TITLE-ABS-KEY (logistics)) AND (LIMIT-TO (DOCTYPE, "ar")). The following numerical analysis is based on the results of this search. Initially, as a result of this search, 50 articles were identified and analyzed. The search was conducted in March 2022; therefore, new articles may have been published since then.

**Figure 2** shows the distribution of published articles based on the search results in Scopus. As **Figure 2** shows, more than 50% of the articles were published in the last 5 years, and this fact shows the increased importance of green supply-chain-focused researches.

**Figure 3** shows the classification of the published articles and research work by the nationality of the authors. As **Figure 3** shows, authors from Europe, Asia, and America are working on research topics focusing on green supply chain design and operation. From a global economic perspective, it is an important fact, that this research field is becoming increasingly important not only in developed countries but also in developing countries.

**Figure 4** demonstrates the distribution of articles by subject area in Scopus. It can be concluded, that the green distribution-related researches are multidisciplinary

**Figure 3.** *Classification of articles by the nationality of the authors based on search results in Scopus.*

**Figure 4.**

*Distribution of articles by Scopus keywords in the field of green distribution-related research.*

researches, where a wide range of science fields is required to solve technological, logistics, human resource management, economic, and ecological problems including business and management, engineering, decision sciences, telecommunication and computer sciences, environmental sciences, social sciences, mathematics and optimization, chemical engineering and materials science. These topics are covered by journals in the following fields: sustainability, operational research, industrial engineering, management research, logistics, manufacturing technologies, mathematics, and transportation business.

An internationally accepted measure of the quality of scientific works is the independent citation. **Figure 5** shows the ten most cited articles based on the results of the Scopus search and the distribution of the independent citations. The *h-index*, which is the largest number *h* of published articles having at least *h* independent citations is in the case of green distribution research is 20. This h-index seems to be acceptable in the field of technology, engineering, and environmental researches, because in the case of other sciences, such as physics, space sciences, clinical medicine, and genetics, there are more papers, more scientists, and more citations.

**Figure 6** demonstrates the distribution of green supply chain-related articles by open access types. Gold open access includes journals published only in open access. In the case of hybrid gold open access, the authors can choose the open access

#### *Supply Chain: A Modeling-Based Approach for Cyber-Physical Systems DOI: http://dx.doi.org/10.5772/intechopen.105527*

#### **Figure 5.**

*Yearly distribution of independent citation of the ten most cited articles in the field of green supply chain-related research [2–11].*

#### **Figure 6.**

*Distribution of green supply chain article from availability (open access) point of view.*

publication. In the case of green open access, the published articles are available in different repositories. In the case of bronze open access, the publisher offers temporally or permanently unlimited free access to the articles. 34 of the analyzed 51 articles are available online, which is an acceptable proportion.

**Figure 7** demonstrates the distribution of the keywords mostly used by the authors of green distribution design-related articles. The analysis of keywords shows, that they can be clustered in the following way: environmental aspects (greenhouse gas emission, CO emission, carbon, climate change, sustainability, carbon footprint); optimization (linear programming, decision making, genetic algorithm, fuzzy models, algorithms, knapsack problems, factor analysis, numerical models, dynamic programming, comparative analysis, game theory); and logistics (distribution of goods, facility location problems, coordination management, network design, transportation, vehicles, chain to chain competition).

The use of keywords e-tailers and e-commerce distribution shows, that the environmental impact is important not for physical distribution but also in the case of e-business and e-commerce solutions, where the design and operation of eco-friendly operation focus on eco-friendly packaging, reusable plastics, purchasing carbon offsets, and reducing shipping distances.

#### **Figure 7.**

*Distribution of used keywords of green distribution-related articles based on the results of Scopus search.*

#### **2.3 Content analysis**

The importance of the optimization of supply chain processes and the technological and logistics resources is underlined also by the fact, that logistics-induced greenhouse gas emissions caused by economic growth block and obstruct the greening process of supply chain solutions, especially in the field of last-mile logistics [12].

The product development process can be integrated with green purchasing, green manufacturing, green distribution, and green reverse logistics, which are an essential part of the green supply chain. This integration can lead to decreased environmental impact in all stages of the supply chain [13]. The product development environment can be also integrated with the forward and reverse flow of the supply chain in the circular economy including production, distribution, and customers in the forward direction and collection, disassembly, recycling, and disposal in the reverse direction to improve the greening process of supply chain solutions [14]. The products and the behavior of consumers can also influence the performance and environmental impact of distribution processes. From product development and labeling point of view, studies show, that consumers prefer green-labeled products and green distribution labels, especially in the case of tier1, tier 2, and tier 3 consumers [15].

Different models are used to demonstrate the impact of green distribution on the environmental impact of the green supply chain. The path analysis is a useful method to analyze this impact and to justify, that the participants of the green supply chain including suppliers, manufacturers, and service providers must focus on the facilities and operation-related policies to increase the performance of those variables [16].

The Nash and Stackelberg game is also a suitable method to analyze the impact of policies and regulations on the equilibrium strategies from sustainability of competitive forward and reverse supply chains focusing on financial aspects and greening [17]. A survey with 43 items was tested using partial least squares structural equation modeling to identify the most common practices facilitating environmental collaboration. The study shows that internal environmental management, eco-design, and green marketing play an important role in the greening process of supply chains, while no substantial impact was identified between green human resources, green information, and systems technology [18].

#### *Supply Chain: A Modeling-Based Approach for Cyber-Physical Systems DOI: http://dx.doi.org/10.5772/intechopen.105527*

Network analysis can be used to perform a wide range of design tasks for green distribution processes including facility location and routing. These design tasks are essential to creating a sustainable and green distribution system, where the optimal location of distribution centers has a great impact on the energy efficiency and greenhouse gas emission of transportation processes [19, 20]. The greening process can be influenced both on the managerial and operational levels [21].

The risk evaluation plays an important role in the operation of green distribution networks because in an uncertain environment the performance of the distribution processes can be influenced by the results of forecasting and super positioning of customers' demands and other system parameters. This importance of risk evaluation is discussed in the case of agricultural products in a cold chain logistics solution, where the perspective of the ecological economy is taken into consideration [22] and it is shown, that the logistics mechanism of distribution processes can be improved by permanent improvement and supervision of logistics intermodal mechanism. Fuzzy models are also used to solve design and operation problems of green distribution problems in an uncertain environment [23].

The coordinated optimization of the complex system of green distribution networks shows a suitable way to take a wide range of influencing factors into consideration while optimizing the green supply chain because the complex model of the green supply chain defines different layers such as a layer of distributors, producers, and customers, and the coordinated optimization model plays the parameters and influencing factors of these players of the distribution network into consideration [24].

The analysis of action mechanism of cross-border supply chain solutions shows, that in the case of large geographical area the establishment of green supply chain models for green distribution has remarkable importance for the implementation and development of the green supply chain [25].

The design and operation of green distribution systems can be also described as an optimization problem of inventory routing problems, where the bi-objective optimization of both inventory costs and fuel consumption using mixed-integer linear programming can lead to an efficient green distribution [26]. Another approach focuses on a stochastic model, which takes profit, service level, and environmental impact as green criteria into consideration [5]. This is a new way of solving inventory routing problems because in recent decades these problems were focused only on economic performance and service level, shortages, delivery delays, and environmental footprint were not considered.

Investigations focusing on the relationships between proactive environmental strategy, green supply chain solutions, and performances of logistics providers show, that the environmental impact can be positively influenced by eco-efficiency and eco-branding through green distribution, inventory management, and reverse processes [27, 28].

Research results show, that e-tailers, third party service providers, and consumers have a great impact on the greening process of distribution, therefore it is important to involve all of these players in the optimization process of distribution networks and build a close communication between them [29], and strengthen green supply chain coordination system [30].

Cities as major population centers represent supply chain solutions with a high density of distribution operations, therefore in urban regions, the greening of lastmile logistics operations is especially important, especially from the health of residents' point of view [31]. Another approach to greening distribution processes in the field of urban planning focuses on the assessment of the impact of the urban intelligent transportation system on the success of the green supply chain management

system. The study validated the hypothesis that an urban intelligent transportation system, knowledge of manufacturers, and business processes have a great positive impact on the success of green supply chain management (green distribution) in the case of agricultural products [32].

The interconnection and hyperconnection of supply chains represent a special problem for supply chain management because transferring products between the centers of different supply chains can cause waiting queues and high environmental pollution. Research focusing on the design of forward and reverse logistics of hyperconnected supply chains shows, that the integrated optimization of queuing problems and transportation networks can lead to the reduction of environmental impact [3]. Other integrated approaches for the optimization of distribution processes focus on the multi-echelon location routing problem, where genetic algorithm and dynamic island model-based heuristics is used to minimize the energy costs associated with transportation [33]. Using a mixed-integer programming model to solve a largescale integrated location-routing problem with genetic algorithm and particle swarm heuristics, it is possible to optimize the number and location of cross-docking facilities in green distribution processes [34].

The application of just-in-time philosophy can improve the efficiency of both manufacturing systems and whole supply chains. As research results in the case of return vehicle supply chains show, the just-in-time model can support the greening processes of conventional solutions to improve environmental awareness and reduce environmental impact of distribution processes [35].

The practices of green supply chain management influence not only the environmental effect of distribution processes, but they have a great impact on organizational performance. The study based on the results of questionnaire-related research describes a theoretical model, which explains the analytical relationships between green supply chain processes and organizational performance [36].

Enhancing stock efficiency and environmental sustainability goals in direct distribution logistic networks can be improved using lean management and green management principles within logistics to reduce the environmental impact of distribution processes [37].

The partner selection process is also an important influencing factor for green supply chain solutions, as in the case of the optimization of a reverse logistics network the results of integrated fuzzy-artificial immune optimization heuristics-based solutions show [38].

The success of green distribution processes is also based on emission measuring operations and estimation of carbon footprint including capturing, calculation, and management of emissions across the transportation and distribution network [39, 40]. The performance evaluation can be based on logistics performance indicators and environmental performance indicators, and these can be integrated into a green logistics performance indicator [4]. Benchmarking is also a suitable tool to support evaluation and process improvement in green distribution networks [11].

For the solution of green supply-chain-related optimization problems, a wide range of integrated optimization and process improvement methods can be used: game theory [7], spanning-tree based genetic algorithm [9], Lagrangian heuristics [10], path analysis [16], integrated CPU-GPU heuristic inspired on variable neighborhood search [41], fuzzy genetic algorithm [42], simulation [43], analytical hierarchy process [44], decision making trial and evaluation laboratory for the identification of cause-effect chain components of distribution systems [45, 46]. Other heuristic

*Supply Chain: A Modeling-Based Approach for Cyber-Physical Systems DOI: http://dx.doi.org/10.5772/intechopen.105527*

algorithms, such as quantum particle swarm optimization are also suitable for the solution of multi-objective optimization of multi-echelon supply chain and distribution, where a wide range of constraints can be considered including capacity, production cost, transportation and material handling cost, greenhouse gas emissions, and time window [47].

Several scenarios and case studies related to the design and operation of green supply chain and green distribution were assessed and evaluated to compare the effects of technology, logistics, human resources, and policies on the efficiency, reliability, and availability of environmental impact of green supply chain solutions. The most important fields of case studies are from general distribution processes [6, 48], but valuable case studies were published in the field of food industry [2], air conditioner manufacturers [7], third party logistics providers [8], motorcycle industry [17], healthcare [28], direct distribution logistic networks [37], electronic equipment and instruments manufacturing companies [38], distribution of fruits and vegetables [49], automotive industry [50], power networks [51], agri-food supply chain [52] and disrupted supply chain solutions in the pandemic era [53]. The methodological framework and main research directions of green distribution networks, including methods, objective functions, case studies and special conditions, and constraints are shown in **Figure 8**.

#### **2.4 Consequences and identification of research gaps**

The consequences based on the above described systematic literature review, including descriptive and content analysis, can be summarized as follows:

• Sustainable distribution is not only influenced by both technological and logistics parameters, but also by product development also has a great impact on the environmental impact of distribution processes.

#### **Figure 8.**

*Methodological framework and main research directions of green distribution networks, including methods, objective functions, case studies, and special conditions and constraints.*


As a research gap, it can be concluded that the analyzed articles are focusing on the analysis and optimization of conventional supply chain and distribution networks and only a few of them discuss the potentials of cyber-physical systems, interconnected and hyperconnected networks.

The increasing number of publications indicates the importance and scientific potential of research on green distribution systems. The articles that addressed the design and operation of green distribution systems are based on conventional supply chain environment, but few of the articles have aimed to research the potentials of Industry 4.0 technologies-based optimization.

Therefore, Industry 4.0 technologies still need more attention and research in the field of integration, cooperation, and globalization of supply chains and distribution networks. Accordingly, the main focus of this research is the modeling and optimization of a cyber-physical distribution network, where not only financial but also environmental aspects are taken into consideration.

The main contribution of this article includes the followings: (1) a systematic literature review with descriptive and content analyses to describe the main research directions and identify research gaps; (2) functional modeling of a cyber-physical distribution network based on Industry 4.0 technologies; (3) mathematical model to find the best parameters for the cyber-physical distribution network from environmental and logistics aspects point of view.

## **3. Description of a cyber-physical distribution network**

Within the frame of this section, the functional and mathematical model of a cyber-physical distribution system is described. The functional model focuses on the transformation of conventional distribution systems into a cyber-physical distribution using Industry 4.0 technologies, while the mathematical model includes "green"

objective functions, such as minimization of energy consumption and greenhouse gas emission, and related constraints (time, capacity, and energy).
