Many existing masonry columns have experienced significant material deterioration, requiring reliable methods for structural assessment and rehabilitation planning. This study evaluates the compressive behaviour of three-dimensional masonry columns under axial compression using two finite element modelling strategies: simplified micro-modelling and macro-modelling. The simplified micro-modelling approach integrates the Extended Finite Element Method (XFEM) with plasticity-based constitutive laws. Masonry units and mortar joints are represented as enlarged continuum elements, while surface-based cohesive interactions simulate interface behaviour. Material crushing under compression is described using the Drucker–Prager model, and XFEM enables crack initiation and propagation without predefined crack paths. In contrast, the macro-modelling approach represents the masonry column as a homogeneous continuum. Numerical simulations are performed using ABAQUS and validated against experimental data from previous studies. Results indicate that simplified micro-modelling provides more accurate predictions of nonlinear compressive response and failure mechanisms than macro-modelling, demonstrating superior capability for masonry column assessment.
Investigating the regularity index of fat point schemes in higher-dimensional projective spaces remains a challenging problem and often relies on explicit computations in lower-dimensional cases. Such results provide valuable evidence for understanding the general behavior of the regularity index and for formulating broader conjectures. In this paper, we completely determine the regularity index of a set of n+4 double points not lying on two lines in the projective space P^n for the two fundamental dimensions n=2 and n=3. More precisely, we establish explicit formulas for the regularity index in both cases. These results contribute to the study of fat point schemes and provide a foundation for future investigations in higher-dimensional projective spaces.
Human activities and climate change have altered the hydrological regime of the Vietnamese Mekong Delta (VMD), but changes in water level trends and frequency variability have not yet been fully assessed. This study uses the Frequency-based Improved Polygonal Trend Analysis (F-IPTA) method to analyze monthly water level variations at the Tan Chau and Chau Doc stations from 1979 to 2023. The results show a decline in water levels during the flood season, from July to October, for high, low, and mean water levels. Low and very low water levels have become more frequent, while high and very high levels have decreased. Transition indicators further reveal shifts in the hydrological season and water levels distribution between the two periods. These findings provide quantitative evidence of changes in the VMD hydrological regime and can support more effective water resource management.
This study investigates ignition-map requirements for a Honda Lead 110cc motorcycle engine fuelled with gasoline, a 30% gasoline 70% NH3, and pure NH3 at 7500 rpm, wide-open throttle, and ϕ=1. Three-dimensional CFD simulations using the Partially Premixed/Zimont-Lipatnikov model were combined with original ignition-map measurements using SmartFi 2 and an oscilloscope. The simulated gasoline MBT timing, 33oCA BTDC, agreed with the measured value of 33.1o CA BTDC. Increasing ammonia content shifted MBT to 42oCA BTDC for the blend and 55oCA BTDC for pure ammonia. At MBT, power decreased from 6.40 kW for gasoline to 5.56 and 4.63 kW, respectively. Predicted NOx decreased from 5500 ppm to 1900 and 1700 ppm. Simulation-experiment NOx deviations averaged 11.8%. The results provide a practical basis for remapping ignition in gasoline-ammonia motorcycle engines.
This paper presents a trajectory tracking control method for autonomous vehicles (AVs) that does not depend on model parameters or velocity sensors, based on a non-recursive control framework. First, the position tracking error of the AVs is defined at a look-ahead reference point. Then, a state observer is designed to estimate the corresponding velocity tracking error, thereby eliminating the dependency of the control system on velocity sensors. Finally, an adaptive controller based on the non-recursive control framework is developed to ensure robust trajectory tracking performance of the AVs under external disturbances. The advantage of the proposed method is that it does not require prior knowledge of the model parameters of the AVs, while being capable of handling uncertainties through a single adaptive parameter. The stability of the method is proven based on Lyapunov theory and is validated through simulation examples in Matlab/Simulink.
