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Data assimilation for unconfined seepage analysis has faced significant challenges due to hybrid causes, such as sparse measurements, heterogeneity of porous media, and computationally expensive forward models. To address these bottlenecks, this paper introduces a physics-informed neural network (PINN) model to resolve the data assimilation problem for seepage analysis of unsaturated earth–rockfill dams. This strategy offers a solution that decreases the reliance on numerical models and enables an accurate and efficient prediction of seepage parameters for complex models in the case of sparse observational data. For the first attempt in this study, the observed values are obtained by random sampling of numerical solutions, which are then contributed to the synchronous constraints in the loss function by informing both the seepage control equations and boundary conditions. To minimize the effects of sharp gradient shifts in seepage parameters within the research domain, a residual adaptive refinement (RAR) constraint is introduced to strategically allocate training points around positions with significant residuals in partial differential equations (PDEs), which could facilitate enhancing the prediction accuracy. The model's effectiveness and precision are evaluated by analyzing the proposed strategy against the numerical solutions. The results indicate that even with limited sparse data, the PINN model has great potential to predict seepage data and identify complex structures and anomalies inside the dam. By incorporating coupling constraints, the validity of our PINN model could lead to theoretically viable applications of hydrogeophysical inversion or multi-parameter seepage inversion. The results show that the proposed framework can predict the seepage parameters for the entire research domain with only a small amount of observation data. Furthermore, with a small amount of observation data, PINNs are able to obtain more accurate results than purely data-driven DNNs. [ABSTRACT FROM AUTHOR]

Cost‐effective, non‐fluorinated polymer proton exchange membranes (PEMs) are highly desirable in emerging hydrogen fuel cells (FCs) technology; however, their low proton conductivities and poor chemical and dimension stabilities hinder their further development as alternatives to commercial Nafion®. Here, we report the inorganic‐organic hybridization strategy by facilely complexing commercial polymers, polyvinyl butyral (PVB), with inorganic molecular nanoparticles, H3PW12O40 (PW) via supramolecular interaction. The strong affinity among them endows the obtained nanocomposites amphiphilicity and further lead to phase separation for bi‐continuous structures with both inter‐connected proton transportation channels and robust polymer scaffold, enabling high proton conductivities, mechanical/dimension stability and barrier performance, and the H2/O2 FCs equipped with the composite PEM show promising power densities and long‐term stability. Interestingly, the hybrid PEM can be fabricated continuously in large scale at challenging ~10 μm thickness via typical tape casting technique originated from their facile complexing strategy and the hybrids' excellent mechanical properties. This work not only provides potential material systems for commercial PEMs, but also raises interest for the research on hybrid composites for PEMs. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious porous structure and insufficient mechanical properties, and few studies have been conducted studying this. In this paper, epoxy resin was used to impregnate the blank of porous metal parts formed by L-PBF with iron-based powder material at a certain temperature, and a cross-linked curing reaction was carried out with three kinds of phenolic resin in different proportions under the action of a curing agent, so as to fill the pores and achieve the desired mechanical properties. The characteristic peaks of each group of epoxy resin were characterized using Fourier transform infrared spectroscopy (FT-IR) and H-nuclear magnetic resonance (1H-NMR) spectrums. The microstructure, decomposition temperature, and residue of four epoxy resin dispersion systems were analyzed with a scanning electron microscope (SEM), a thermal gravimetric analyzer (TGA), and derivative thermogravimetry (DTG). The results show that the density of the porous metal parts was obviously improved, the heat resistance temperature of the parts could reach 350 °C, and the tensile strength of the sample after EP2-1 impregnation was increased by 4–6 times after curing at 160 °C for 6 h. Therefore, the use of an epoxy resin dispersion system can increase the porosity of L-PBF porous metal parts, but can also significantly improve their mechanical properties, which can help them to meet the requirements of applications as model materials, biological materials, and functional materials to provide a feasible solution. [ABSTRACT FROM AUTHOR]

Constructing tunnel is a difficult and expensive process which deserves special attention. In this article, cracking behavior in a highway tunnel structure during construction period is researched, including figuring out the causes and evolution of crack. Large deformation of rock mass is the major inducement of the damaging behavior, which is obtained from the field investigation. The layers of the ground were monitored with the displacement of tunnel while the numerical analysis was realized with extended finite element method. The results highlight the regions of cracking on tunnel bottom structure, which emphasizes the accuracy of model and the influence of poor geological condition. This work demonstrates that the carbonaceous slate stratum plays an important role in the stability of tunnel structure, which leads to the phenomenon of stress concentration in tunnel bottom region. Moreover, the implemented numerical model also simulates the process of the damaging behaviors of tunnel structure induced by the poor geological condition, which is similar to the results from field investigation and provides the design basis for maintenance work.

Mastering the variations in the stability of a polarization vortex is fundamental for the development of ferroelectric devices based on polarization vortex domain structures. Some phase field simulations were conducted on PbTiO3 nanofilms with an initial polarization vortex under uniaxial tension or compression to investigate the conditions of vortex instability and the effects of aspect ratio of nanofilms and temperature on them. The instability of a polarization vortex is strongly dependent on aspect ratio and temperature. The critical compressive stress increases with decreasing aspect ratio under the action of compressive stress. However, the critical tensile stress first decreases and then increases with decreasing aspect ratio, then continues to decrease. There are two inflection points in the curve. In addition, an elevated temperature makes both the critical tensile and compressive stresses decline, and will also cause the aspect ratio corresponding to the inflection point to decrease. These are very important for the design of promising nano-ferroelectric devices based on polarization vortices to improve their performance while maintaining storage density. [ABSTRACT FROM AUTHOR]

After the separation of the highway and railway in an underwater tunnel, varying spacing underpass disturbance and detachment between soil-structure occurred during a metro tunnel parallelly crossing an existing open-cut tunnel. In this study, a case study is conducted on the metro tunnel on the north bank section of the Yellow river-crossing tunnel in Jinan, China, and a refined three-dimensional simulation model considering the detachable strata-structure interface and structural deformation joint is established to investigate the influence of shield tunneling on stratum-structure detachment and the existing structure under various reinforcement schemes. The results reveal the following: (1) The maximum ground settlement is reduced by 52% and the peak superposition effect of the settlement curve is effectively controlled after the column pile reinforcement is adopted. (2) The maximum lateral differential settlement and the maximum settlement of the existing structure floor are reduced by 43.4% and 47.0%, respectively, during shield tunneling after using reinforcement of column pile and three-axis mixing pile. (3 ) The maximum detachment between the tunnel floor and the soil due to shield tunneling is 1.44 mm without reinforcement. Compared with the reinforcement of three-axis mixing pile, the reinforcement of column pile is more effective in reducing the detachment between the tunnel floor and the soil. (4) The maximum tensile stress increment of the existing structure without reinforcement measures exceeds the control limit, and the reinforcement of three-axis mixing pile tends to increase the tensile stress increment within the grouting range of the existing structure, while the use of column pile combined with three-axis mixing pile reinforcement can effectively reduce the tensile stress increment of the existing structure by 50% . When shield tunneling parallelly under existing structure, it is safer and more effective to take the ground displacement control (anti-detachment) and structural stress control into consideration than to strengthen the single reinforcement measure. [ABSTRACT FROM AUTHOR]