## 2 Related Work
### The Design of Simulation Approaches for Railway Network Disturbance Events  
(1) Railway Network Disturbance Events  
In the operation of modern society, the railway network plays a vital role. It not only undertakes a substantial volume of cargo and passenger transportation tasks but also constitutes a significant component of the nation's critical infrastructure. Nevertheless, diverse risks present severe challenges to the railway network. Railway disruption events denote any sudden and unplanned occurrences that interfere with the normal operation of the railway network, affect the punctual arrival and departure of trains, and may even lead to temporary or long-term disruptions of railway services. Such events are inherently unpredictable in both time and location, and can originate from either natural or human-induced causes. Characterized by randomness, abruptness, and urgency, these disruptions often require prompt and effective countermeasures to mitigate their adverse impacts. Natural emergencies such as earthquakes, floods, typhoons, and landslides are natural phenomena that are often associated with changes in the natural environment and are typically difficult to accurately predict in terms of the time and location of occurrence. Man-made emergencies may encompass terrorist attacks, industrial accidents, traffic accidents, and sudden public health incidents. These events are often closely related to human activities and may be caused by technical glitches, poor safety management, or malicious acts. This article broadly classifies these disruption events into four major categories: external attacks, natural disasters, technical malfunctions, and fluctuations in passenger and cargo traffic:  
1. External attacks: This category encompasses all disruptions to the railway network resulting from malicious human behavior. These may involve cyberattacks targeting railway control systems or physical sabotage of critical infrastructure such as tracks, bridges, or signaling equipment. Such attacks can lead to immediate and severe interruptions of railway operations, with potentially far-reaching consequences. 2. Natural disasters: The influence of natural disasters is extensive and profound. Extreme weather conditions like earthquakes, floods, and blizzards may cause damage to railway facilities and disrupt transportation. 3. Technical malfunctions: The operation of the railway network highly relies on the reliability of facilities and equipment. Failures in key components--such as signaling systems, tracks, and bridges--can compromise operational continuity and result in service interruptions. 4. Fluctuations in passenger and cargo traffic: Drastic changes in passenger and cargo traffic due to holidays, special events, or market variations pose significant challenges to the scheduling flexibility and capacity adaptability of the railway system. (2) Simulation Method of Disturbance Events  
By establishing a connection between the four major disruption events of the railway network and the mathematical tools of complex networks, and simulating the disruption events of the railway network through the utilization of complex network attack strategies, it becomes feasible to analyze and prevent the potential impacts of these events on the railway network. Generally, attack strategies for complex networks can be categorized into random attacks and purposeful, deliberate attacks. In the absence of detailed network information, random attacks are commonly employed. These attacks do not target specific nodes and are independent of the importance of the affected entities. Conversely, when partial or comprehensive information about the network is available, deliberate attacks are more likely to be executed. Such attacks take into account the significance of the targets and prioritize attacking the more critical elements within the network. Notably, real-world external attacks are similar to deliberate attacks in complex network theory, especially those based on node degree.