Abstract Strain-hardening/engineered cementitious composites (SHCC/ECC) are fiber-reinforced concrete with outstanding tensile performance, but its widespread application is constrained by the high initial material cost primarily comes from high-performance polymer fibers like polyvinyl alcohol (PVA). This study explores partial replacement of PVA fibers with recycled polyethylene terephthalate (PET) fibers (with and without surface treatment) to reduce the cost and environmental impacts of ECC without compromising its flexural performance. Nine ECC mixes with a constant total fiber content of 2.0 vol% were tested under four-point bending. With 50% PET replacement, ultimate tensile strain decreased from 4.63% (control) to 1.83%–2.16%, whereas flexural strength only decreased from 11.40 MPa (control) to 10.10–10.19 MPa, and curvature capacity remained 79%–82% of the control. At 100% PET replacement, surface treatment improved the flexural ductility by about 70%. Finite element analysis confirmed the test results in terms of both flexural strength and deformation with good alignments. Additionally, overall performance evaluation of the developed ECC was assessed through a five-dimensional mechanical performance assessment framework and breakdown analysis of embodied energy, CO 2 emission, and material cost. The results support the hybrid PVA/PET fiber system as a feasible means of creating sustainable ECC for structural applications.
The middle-lower Yangtze River region hosts extensive aeolian deposits, among which the Poyang Lake sandy land (PYSL) constitutes a prominent and geomorphologically distinctive example. However, the relative contributions and synergistic interactions between aeolian and fluvial processes in shaping these landscapes remain insufficiently quantified, primarily due to methodological limitations and spatially fragmented research efforts. This knowledge gap impedes both robust paleoenvironmental reconstructions and the development of effective strategies for mitigating sand-related hazards. Here, an integrated provenance study of the PYSLs was conducted, combining detrital zircon U-Pb geochronology, heavy mineral analysis, and grain-size distribution. The multidimensional scaling (MDS) diagrams and inverse Monte Carlo models (IMCM) of detrital zircon ages indicate major provenance areas are the eastern Cathaysia Block (mainly the south and central Jiangxi ranges; 16.2-85.5%) and the Jiangnan Orogenic Belt (primarily the Jiuling Mountains; 14.5-83.8%). The results demonstrate pronounced spatial heterogeneity in sediment direct sources. The central PYSLs are primarily supplied by the Ganjiang and Xiushui rivers, whereas the northern PYSL is dominated by the Yangtze and Ganjiang rivers, and the southern PYSL derives sediment mainly from the Jinjiang river. Obviously, wind plays a subordinate role in large-scale sediment reworking, as evidenced by the marked compositional heterogeneity between the northern and southern PYSL. Nevertheless, aeolian processes remain dynamically active in the local redistribution of sediments within the central PYSLs. These findings collectively emphasize that topographic factors must be carefully considered in paleoenvironmental studies of aeolian deposits. However, surface samples provide only a limited view into longer-term landscape evolution.
Abstract Microbially induced calcium carbonate precipitation (MICP) is a promising green soil improvement technology. The micro- and mesoscale deposition state of calcium carbonate influences soil strength, but existing numerical models often neglect precipitation patterns and particle contact modes, hindering the clarification of micro–meso–macro property relationships. In this study, we propose a novel discrete-element method modeling scheme that simulates calcium carbonate precipitation by generating microparticles between sand grains and at their contacts. The model accounts for three key interaction types: sand–sand contacts, sand–calcium carbonate particle contacts, and calcium carbonate–calcium carbonate particle contacts. The results indicated that selecting appropriate particle contact models based on interparticle mineralization effects could more accurately characterize the microscale interaction mechanisms and mineralization characteristics of calcium carbonate-improved soils. An analysis of the influence of varying calcium carbonate content on the mechanical properties of MICP-mineralized sand revealed that both the peak and residual strengths increased significantly with higher calcium carbonate content, reaching 1.2–8.7 times those of untreated samples. An increase in confining pressure was found to enhance the deformation modulus of the specimens, while the modulus exhibited a critical threshold effect with increasing calcium carbonate content: the increase was gradual below 3%, but became abrupt beyond this value. Cohesion remained low when the calcium carbonate content was below 3% but improved markedly once this threshold was exceeded, owing to the formation of a stable mineralization network. The internal friction angle initially experienced a slight reduction at low calcium carbonate content but increased substantially with further content increase.
We study self-bound quantum droplets in the regime dominated by microwave-induced non-axisymmetric dipole−dipole interactions, using the extended Gross−Pitaevskii equation with the Lee−Huang−Yang corrections. We identify the existence region through numerical simulations and employ an anisotropic Gaussian−super-Gaussian variational ansätz to capture the characteristic density profile of the droplets, with a Gaussian profile along the narrow x direction and super-Gaussian profiles in the extended (y, z) plane. Within this variational framework, we characterize the self-binding, spatial localization, and density-compression properties of the droplets and find good agreement between the variational predictions and the numerical results. Collisions between droplets moving along different directions reveal a strong directional dependence, with outcomes ranging from quasi-elastic rebound and merger to fragmentation. In addition, we explore the rotational dynamics of a single self-bound droplet about all three Cartesian axes, revealing rich and controllable three-dimensional rotational dynamics. Together, these results demonstrate how non-axisymmetric dipolar interactions provide versatile means for controlling the translational, collisional, and rotational dynamics of self-bound quantum droplets.
Variational quantum algorithms (VQAs) constitute a prominent framework for exploring the capabilities of near-term quantum computers. As the effectiveness of VQAs depends heavily on the design of variational quantum circuits, Quantum Architecture Search (QAS) has emerged as a critical research area to automate the discovery of high-performing circuit structures. This paper reviews key advancements in current research on QAS, including its core concepts, representative methodologies, and applications. The content is structured to ensure broad accessibility for a diverse audience of researchers while preserving the core principles of complex methodologies. In addition, we discuss remaining challenges and suggest potential research directions to offer perspectives on future exploration in this rapidly evolving field.
