# Research on Supply Chain Network Resilience: Considering Risk Propagation and Node Type
## 2 Literature Review
### Supply Chain Network Resilience  
The concept of resilience originated from the study of resilient mechanics in the discipline of physics [32]. It refers to the property of an object that undergoes deformation under an external force and can recover its original size and shape when the external force is withdrawn. The concept of resilience has been widely used, for example, in psychology [33; 34], ecology [35], and economics [36; 37]. It is defined differently in different research areas. The concept of SCNR originated in the field of supply chain risk management [38]. [PERSON] and [PERSON] [39] defined supply chain resilience as the ability of a supply chain to recover quickly and to maintain normal business levels when it is disrupted by unexpected events. Generally speaking, scholars have defined and studied SCNR from different perspectives [6]. As supply chains become more complex and global, the impact of regional disruptions can be far-reaching and long-lasting [15]. A real-life SCN will be affected by many different types of risk [40; 41]; in this context, in order to reduce the effect of risk to reduce business losses, scholars have conducted a lot of research on SCNR. How to cope with the impact of disruptions and improve SCNR has attracted the interest of an increasing number of scholars [16; 39]. Relevant studies have been conducted using both quantitative and qualitative analysis methods [15; 16; 42]. However, [PERSON] et al. [16] mentioned that most of the literature focuses on the resilience capabilities of individual enterprises and does not consider the impact of network structures on network resilience from the perspective of complex networks. Industry 4.0 is the fourth industrial revolution, led by smart manufacturing, which has generated many frontier technologies [17]. These technological tools play a key role in improving SCNR. The technological tools of Industry 4.0 can improve SCNR through digitization, intelligence, additive manufacturing, and cloud computing [18; 19; 20]. [PERSON] et al. [21] explored the impact of Industry 4.0 on supply chain performance, drawing on information processing theory and a resource-based view. [PERSON] and [PERSON] [22] investigated the impact of digitalization and Industry 4.0 on the analysis of chain reactions and disruption risk control in supply chains. In the era of Industry 4.0, supply chain managers can utilize advanced technological tools to better understand and control the state of an SCN to improve SCNR. The structure of an SCN is important for its response to disruptions [43; 44]. [PERSON] et al. [44] used optimization methods to allow decision makers to select nodes and edges to construct networks that maximize supply chain performance. But the method cannot be applied to large-scale SCNs. Many scholars have used network science methods to study the impact of different network types [15; 27; 43]. However, for different network types, their network characteristics vary particularly widely, yielding very rough and unrefined conclusions [25]. Moreover, real-life SCNs do not exclusively belong to a certain type of network and have more complex network characteristics [16]. Therefore, there are limitations if we classify SCNs into certain network types and study the resilience of SCNs by examining the differences between different network types. A small number of scholars have recognized the aforementioned shortcomings and proposed focusing on the impact of network characteristics on resilience [15; 16], but there are still some network characteristics that have not been studied. Managers are able to adjust the network characteristics to change an SCN's structure but cannot change the network type [16]. Network characteristics are more applicable to the study of resilience in real-life SCNs. Most realistic SCNs have scale-free and small-world characteristics [45]. The main difference between our study and those of [PERSON] et al.