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AIS ship-type code categorizes ships into broad classes, such as fishing, passenger, and cargo, yet struggles with finer distinctions among cargo ships, such as bulk carriers and containers. Different ship types significantly impact acceleration, steering performance, and stopping distance, thus making precise identification of unfamiliar ship types crucial for maritime monitoring. This study introduces an original classification study based on AIS data for cargo ships, presenting a classifier tailored for bulk carriers, containers, general cargo, and vehicle carriers. The model's efficacy was tested within the Changhua Wind Farm Channel using eight classification algorithms across tree-structure-based, proximity-based, and regression-based categories and employing standard metrics (Accuracy, Precision, Recall, F1-score) to assess the performance. The results show that tree-structure-based algorithms, particularly XGBoost and Random Forest, demonstrated superior performance. This study also implemented a feature selection strategy with five methods, revealing that a model trained with only four features (three ship-geometric features and one trajectory behavior feature) can achieve high accuracy. Conclusively, the classifier effectively overcame the challenges of limited AIS data labels, achieving a classification accuracy of 97% for ships in the Changhua Wind Farm Channel. These results are pivotal in identifying abnormal ship behavior, highlighting the classifier's potential for maritime monitoring applications. [ABSTRACT FROM AUTHOR]

Recent advancements in information technology and ship equipment have allowed for the collection of large amounts of data on maritime traffic through automatic identification systems (AIS). This data is crucial for risk assessment and navigation safety, as it provides insights into ship behavior. Researchers have used machine learning and deep learning techniques to analyze AIS data and improve maritime safety. This document summarizes several research papers on topics such as ship classification, anomaly detection, ship grounding frequency estimation, performance-shaping factors in oil tanker operations, resource allocation in search and rescue, container ship stowage planning, and route identification in ice-covered waters. These papers contribute to the understanding of maritime safety and efficiency and provide recommendations for future research. [Extracted from the article]

This study proposes a multi-ship collision avoidance and route generating algorithm based on the general requirements of the International Regulations for Preventing Collisions at Sea (COLREGs) and the artificial potential field (APF) method. The velocity potential field is used as the field function of APF method. The algorithm consists of two modes, the course-changing and the track-keeping modes based on the velocity potential of vortex and dipole, respectively. The course-changing mode guides the ship to turn away from the obstacles according to the vector field of vortex potential. The track-keeping mode steers the ship back to and along on a pre-designed track in accordance with the vector field of dipole potential. The data of distance to the closest point of approach (DCPA), time to the closest point of approach (TCPA) and bearing angle evaluated from a maneuvering simulation are the acquired parameters of the proposed collision avoidance algorithm. The algorithm is straightforward and very simple to implement, and is suitable for the real time and distributed intelligent collision avoidance system. Simulation results indicate that the anti-collision formulation can avoid collision safely with the desired distance and indicate that the algorithm proposed can work effectively. [ABSTRACT FROM AUTHOR]

We present a frequency-dependent phonon Boltzmann transport equation (BTE) solver to study phonon transport in arbitrary geometries. For composite and porous structures, most simulations adopted either gray-medium approximation or geometric simplification in phonon BTE model. To show the importance of considering the frequency-dependent phonon transport, transverse thermal transport in periodic porous silicon (PS) with aligned square-cylindrical pores is investigated by the present frequency-dependent phonon BTE solver and gray-medium phonon BTE solver. It is found that phonon size effect is underestimated by adopting the gray-medium approximation in sub-micron scale. To demonstrate geometry effect, the frequency-dependent phonon BTE solver is applied to study transverse thermal transport in the PS with square-cylindrical and circular-cylindrical pores for various characteristic sizes and porosities. The pore shape is found to make great difference to the thermal conductivity of the PS when the characteristic size is decreased or the porosity is increased. Our results indicate the importance of considering the frequency dependence of phonon transport as well as the exact geometry of material structure in the analysis of micro- and nanostructured materials. [ABSTRACT FROM AUTHOR]

With discretized particle velocity space, a unified gas-kinetic scheme for entire Knudsen number flows has been constructed based on the Bhatnagar–Gross–Krook (BGK) model (2010. J. Comput. Phys., 229, 7747–7764). In comparison with many existing kinetic schemes for the Boltzmann equation, besides accurate capturing of non-equilibrium flows, the unified method has no difficulty to get accurate solution in the continuum flow regime as well, such as the solution of the Navier–Stokes equations. More importantly, in the continuum flow regime, the time step used by the unified scheme is determined by the Courant-Friedrichs-Lewy condition, which can be many orders larger than the particle collision time. In some sense, the unified method overcomes the time step barrier for many kinetic methods, such as direct simulation Monte Carlo (DSMC), direct Boltzmann solver and many other kinetic solvers. The unified scheme is a multiscale method, where the macroscopic flow variables and microscopic gas distribution function are updated simultaneously. In an early approach in the unified BGK (U-BGK) scheme, the heat flux in the BGK model is modified through the update of macroscopic flow variables, then this modification feeds back into the update of non-equilibrium gas distribution function. In this paper, we are going to develop a unified scheme for the Shakhov model, the so-called unified Shakhov (U-Shk), where the heat flux is corrected directly through the modification of gas distribution function. Theoretically, it will be shown that current U-Shk is more consistent than the U-BGK for the highly non-equilibrium flow computations. The study of shock structures from low to high Mach numbers will be presented and the simulation results will be compared with DSMC solutions as well as possible experimental measurements. The result improvement of U-Shk over U-BGK is clearly achieved. Based on the simulation results, now we fully believe that the unified scheme is an accurate and efficient flow solver in all Knudsen number flow regime. [ABSTRACT FROM PUBLISHER]

Aim: To observe the effect of vincristine on hepatitis B virus (HBV) replication in vitro and to study its possible mechanisms., Methods: Vincristine was added to the cultures of two cell lines stably expressing HBV. Then, the levels of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and hepatitis B core antigen (HBcAg) in the supernatants or cytoplasm were examined using by enzyme-linked immunosorbent assay and Western blot. The HBV pregenome RNA (pgRNA) was detected using reverse transcription-PCR and real-time fluorescent quantitative PCR (RT-qPCR), and viral DNA was detected using Southern blot and RT-qPCR. Cell proliferation after drug treatment was detected using the BrdU incorporation test and the trypan blue exclusion assay. Cell cycle and cell apoptosis were examined using flow cytometry and Western blot., Results: Vincristine up-regulated HBV replication directly in vitro in a dose-dependent manner, and 24-h exposure to 0.1 μmol/L vincristine induced more than 4-fold and 3-fold increases in intracellular HBV DNA and the secretion of viral DNA, respectively. The expression of HBV pgRNA, intracellular HBsAg and HBcAg, and the secretion of HBeAg were also increased significantly after drug treatment. Most importantly, vincristine promoted the cell excretion of HBV nucleocapsids instead of HBV Dane particles, and the nucleocapsids are closely related to the HBV pathogenesis. Furthermore, vincristine inhibited the proliferation of cells stably expressing HBV. The higher the concentration of the drug, the more significant the inhibition of the cell proliferation and the stronger the HBV replication ability in cells. Flow cytometry indicated that cell cycle arrest at S-phase was responsible for the cell proliferation inhibition., Conclusion: Vincristine has a strong stimulatory effect on HBV replication and induces cell cycle arrest, and cell proliferation inhibition may be conducive to viral replication.