## 1 Introduction  
In the intricate web of global trade and maritime logistics, port cranes have emerged as critical linchpins, ensuring the seamless and efficient transfer of cargo containers between ships and the shore. They are the unsung heroes of the supply chain and work tirelessly to meet the ever-increasing demands of international trade. These cranes are marvels of engineering and are composed of a sophisticated array of components, such as booms, jibs,cables, trolleys, and slewing bearings. Each component plays a vital role in the precise handling of heavy loads. The boom rises significantly from a robust base, providing the necessary height and reach, whereas the jib extends with remarkable accuracy. Cables and trolleys work in perfect harmony to lift and move cargo, and slewing bearings enable the crane to rotate precisely to align with ship positions [1]. A visual representation of the key structural and functional components of a modern ship-to-shore crane is provided in Figure 1 for clarity and reference.  
However, this complexity renders port cranes vulnerable to wear and tear. The relentless cycle of lifting heavy loads, the dynamic stresses of acceleration and deceleration, and corrosive marine environments gradually degrades their structural and mechanical integrity [2]. As international trade continues to expand and port operations intensify, the impact of crane downtime has become increasingly severe. Operational downtime in port cranes can impede cargo handling efficiency, leading to delays in port activities and broader disruptions across the logistics chain [3]. Therefore, implementing effective condition monitoring and maintenance strategies is essential to uphold the reliability and safety of crane operations.  
Traditional non-destructive testing (NDT) techniques are typically periodic, manual inspections that detect surface or internal flaws in structural components. In contrast, structural health monitoring (SHM) employs permanently installed sensors to continuously track structural behavior and integrity over time. Remote non-destructive testing (RNDT) represents an emerging paradigm that merges the diagnostic precision of NDT with the continuous sensing of SHM, enhanced through Internet of Things (IoT) integration. In this context, the use of vibration and acoustic emission (AE) sensors, networked via IoT platforms, offers real-time insight into port crane health. Vibration sensors identify dynamic anomalies such as gear misalignment or bearing wear, while AE sensors detect stress waves associated with crack initiation or material degradation. Through IoT-enabled data  
Figure 1: Key components of a modern ship-to-shore crane.  
acquisition and analysis, RNDT enables predictive maintenance, allowing port operators to intervene before minor faults evolve into critical failures or unscheduled outages.  
A review of 100 journal articles shows that while vibration and AE sensors have been widely studied in various fields, their application to port cranes is still limited. Although a few studies have lightly touched on related topics, integrated research on applying these sensors to port cranes in conjunction with the IoT is still in its infancy. Given the current state of technology, combining vibration and AE sensors with IoT for port crane monitoring is not only novel, but also practical and feasible. This approach could significantly enhance the safety and reliability of port operations, reduce inspection costs, and improve operational efficiency, thereby providing substantial benefits to the port industry.