This study presents a parameter estimation methodology for uncertain differential equations with jumps, which are widely used to characterize complex phenomena in finance, physics, engineering, and other interdisciplinary fields. Specifically, we propose an adaptive threshold estimation method tailored to these equations. Using maximum likelihood estimation, we construct a feasible parameter estimation framework via an algorithm. Illustrative experiments based on a simulation example and a real-world empirical dataset are carried out to validate the proposed approach. Furthermore, we compare our method with state-of-the-art approaches. Finally, we discuss future research directions and summarize the main conclusions.
We prove the existence, uniqueness and regularity of weak solutions of new thermodynamically consistent two-phase porous media flow models neglecting gravity. Introducing fully implicit time semi-discrete and fully discrete approximations of a weak formulation of the model and using the zeros of vector field theorem, we show the existence of weak solutions for the fully discrete approximation. The existence of weak solutions of fully implicit time semi-discrete approximation and the weak formulation of the model are derived by weak convergence techniques and an energy stability estimate. Subsequently, by the Gr & ouml;nwall inequality, we prove the uniqueness result under the smoothness assumption on the chemical potential. Introducing artificial and complementary pressures and combining them with the theory of elliptic partial differential equations, we establish the regularity of the weak solution for the model with complete Neumann boundary conditions.
On April 5, 2017, at 06:09:12 UTC, a shallow-focus earthquake with a moment magnitude (Mw) of 6.1 struck the Alghur region in northeastern Iran. Understanding how fault structures influence rupture processes and how satellite-based Interferometric Synthetic Aperture Radar (InSAR) observations can improve seismic hazard models remains a key challenge in earthquake research. This study employs Sentinel-1 Terrain Observation with Progressive Scans SAR (TOPS) InSAR data to estimate co-seismic and post-seismic ground deformation associated with the Alghur earthquake. We conducted time-series InSAR analyses to detect displacement patterns and produce high-resolution deformation maps, complemented by field-based structural investigations to identify and characterize major fault traces. Results reveal localized deformation along the southwestern block of the Alghur fault, with fault-plane solutions indicating crustal shortening consistent with the tectonic regime of the eastern Alborz range, in agreement with USGS observations. The interferometric analysis indicates uplift of up to 9 cm in the northeastern fault block, suggesting a complex deformation mechanism. This study demonstrates the effectiveness of Sentinel-1 InSAR combined structural analysis for quantifying earthquake-induced ground deformation and understanding fault behavior in tectonically active regions. The graphical abstract provides a concise visual overview of the study by integrating key geographic, methodological, and analytical components. Regional satellite imagery and geological maps position the study area in northeastern Iran, emphasizing the tectonic setting and the epicentral location of the 5 April 2017 Alghur earthquake. The central methodological framework outlines a sequential workflow comprising data acquisition, Sentinel-1 SAR pre-processing, DInSAR-based deformation analysis, field structural investigations, and the final integration of remote sensing and field-derived results. This workflow demonstrates how co-seismic and post-seismic deformation signals were extracted from SLC data, transformed into interferograms, and subsequently converted into LOS displacement maps. Complementary field photographs, structural measurements, and geological mapping validate fault orientations and kinematic characteristics through direct on-site observations. The final deformation products, particularly the DInSAR displacement maps, highlight the principal finding of up to 9 cm of uplift in the northeastern fault block, underscoring the complexity of the earthquake-induced deformation pattern. Sentinel-1 InSAR mapped co- and post-seismic deformation of the 2017 Alghur quake. Localized slip detected along the southwestern block of the Alghur fault. Up to 9 cm uplift observed in the northeastern fault block from InSAR data. Integrated InSAR and field evidence improved the understanding of fault behavior.
A novel series of porphyrin-polyurea covalent organic polymers (COPs) was designed for CO2-epoxide cycloaddition to systematically investigate the influence of metalation sequence on structural ordering and catalytic behavior. Two cobalt-porphyrin-based COPs, PUa-CoDPP and PUa-DPPCo, were synthesized through pre-metalation and post-metalation strategies employing amine-isocyanate polycondensation and solution-phase metal coordination, respectively. Comprehensive characterization revealed that the pre-metalated system maintains high crystallinity, hierarchical porosity, and homogeneous dispersion of Co-N4 sites via controlled monomer assembly, whereas the post-metalated counterpart exhibits structural degradation and heterogeneous active sites due to coordination constraints within the preformed framework. In the solvent-free cycloaddition of CO2 and propylene oxide, PUa-CoDPP achieves a near-quantitative yield (> 99%) and exhibits superior recyclability, substantially outperforming PUa-DPPCo. This performance disparity is mechanistically attributed to three sequence-dependent factors: coordination completeness of active sites, framework-regulated metal accessibility, and pore architecture-mediated substrate diffusion. This study establishes the metalation sequence as a decisive design parameter for engineering high-performance metalloporphyrin polymers that reconcile catalytic efficiency with operational durability.
This work aims to investigate the triaxial fatigue characteristics of rock under the influence of different stress amplitude factors. In the experiments, multistage increasing-amplitude cyclic loading was performed on the sandstone specimens. Two loading modes were designed to consider the influence mechanism of cyclic stress amplitude (including upper stress limit, lower stress limit, and amplitude increment) on the fatigue mechanical properties and fracture behavior of sandstone. The stress–strain curves, mechanical parameters, and macroscopic failure characteristics of sandstone specimens were analyzed under multistage cyclic loading considering the various cyclic stress amplitude factors. Based on the proposed stress path, the impact of stress upper limit history on the conventional triaxial mechanical behavior of sandstone specimens was evaluated, and a conceptual model was proposed. The influence mechanism of stress amplitude increment on the microfracture characteristics of sandstone specimens was further discussed through scanning electron microscopy observations. The research findings provide scientific basis for fatigue failure in deep underground engineering.
