State Of Vessels Research Articles

Real-time digital twin of autonomous ships based on virtual-physical mapping model

The advancement of intelligent technology has propelled the development of smart unmanned vessels into a new phase. To address the urgent demands of current smart ship development, this paper develops a comprehensive ship digital twin system based on a virtual-real mapping algorithm, focusing on the fundamental elements of digital twin model construction. Using the smart unmanned experimental ship Dolphin 1 as a prototype, a digital twin virtual model is proposed. This system leverages real-time internal and external data from the entire vessel to track its navigational status, performance indicators, sailing trends, and surrounding flow field information, offering coordinated “human-machine” navigation assistance. Based on historical data collected from the vessel's long-term navigation, a real-time precise prediction of the vessel's navigational state and hydrodynamic performance is conducted using physics-informed neural network algorithm. This establishes a self-learning iterative virtual-physical mapping model that enables autonomous updates and evolution. As the real navigation data of the vessel continuously update, the virtual model can more accurately simulate the vessel's state in real time. The proposed digital twin model has been tested through sea trials under real sea conditions, demonstrating its high accuracy, robustness, and potential for enhancing navigational safety and efficiency. This system marks a significant step forward in the integration of digital twin technology with maritime navigation, providing a valuable tool for the future development of smart shipping.

Research of Divergence Trajectory with a Given Risk of Ships Collisions

There were considered the issues of the optimal collision avoidance in the target’s risk field. A method of optimal divergence by course maneuvering is proposed, which makes it possible to minimize the divergence trajectory for a given risk of collision and consists in organizing the movement of the vessel along the trajectory of a given risk. The risk field of the target is a normal distribution law characterized by the root-mean-square parameters of the uncertainties associated with measurement errors of the parameters of the vessel's state vector and target, errors of actuators, errors of the used mathematical models, errors of calculation, etc. The operability and efficiency of the proposed method, algorithmic and software were tested on the Imitation Modeling Stand, which is the Navi Trainer 5000 navigation simulator and a model of on-board controller included in its local network with the software of the risk divergence module. The Imitation Modeling Stand allows to work out the software of control systems, including the considered optimal divergence module, in a closed circuit with the Navi Trainer 5000 navigation simulator, using all its advantages.

Long-Term Follow-Up Examination of the Internal Jugular Vein After Vessel-Sparing Implantation of a Hickman Catheter or Port Catheter.

Introduction: Both a Hickman catheter (HC) and port catheter (Port) can be inserted either percutaneously by the Seldinger technique or by surgical venous cut-down. Catheters are inserted with a vessel-sparing technique when they are placed in the internal jugular vein (IJV) by venous cut-down. Although this technique is common, data are sparse regarding the vessel's state at long-term follow-up. This study was aimed at determining the flow pattern and constitution of the IJV after vessel-sparing implantation of an HC or Port and comparing the outcomes to those of implantation with the Seldinger technique.Methods: One hundred children (58 boys, 42 girls) between 33 days and 18 years of age who underwent a vessel-sparing implantation of an HC or Port in the IJV were prospectively included. All patients underwent surgical venous cut-down at a single institution. Patency and shape of the IJV were determined by ultrasound and categorized according to 2 possible outcomes: relevant alteration (including occlusion of the IJV) and no relevant alteration, with relevant alteration defined as changes that caused an altered flow pattern.Results: Median age was 6 years at the time of operation, and the median indwelling time of catheters was 271 days. Twenty-two of our patients (22%) showed relevant alterations. These changes included high-grade stenosis or lesion in 13 patients (13%) and occlusion in 9 patients (9%). There were no operation-associated complications, such as pneumothorax, hematopericardium, or accidental puncture of the carotid artery. Statistical analysis did not reveal any specific parameter as a risk factor for relevant structural abnormalities.Discussion: In a comparison of our data to the literature, venous cut-down showed an alteration rate of 26% and a patency rate of 85%, whereas the Seldinger technique was found to cause alteration in 15%, with a patency rate of 97% but a successful placement rate of only 90.3–91.6%.Conclusion: The indication for long-term catheter placement may determine which method is preferable. A child who is likely to need more catheters in the future might benefit from the Seldinger technique, since there is a higher chance of long-term patency of the vessel. A patient undergoing chemotherapy might benefit more from the surgical venous cut-down with less placement-associated complications.

An Integrated Approach to Shipboard System and Equipment Testing for Improved Maintenance Management

Commercial operators today are required to maintain maximum vessels in-service levels and, with government vessel operators competing for decreasing operating funds, the management of ship maintenance and repair (M&R) has become a highly visible area which can have a significant impact on overall vessel operating costs. As an approach to consolidate, improve, and simply better manage a vessel's state of material condition and M&R requirements, an integrated shipboard Material Condition Assessment Program can be implemented which provides a comprehensive evaluation and assessment of the various critical components on a ship-specific basis. This approach will integrate all vessel material condition assessment techniques and periodic surveys whose results can be used for advanced maintenance planning and budgeting. The approach and methodology employed and described in this paper are not new, having been tried and proven to varying degrees in the marine and related industrial fields, and are considered within the constraints of day-to-day vessel operation and maintenance management.