The interfacial transition zone (ITZ) significantly influences the mechanical properties and durability of lightweight aggregate concrete (LWAC), yet existing research on the ITZ in LWAC remains fragmented due to varied characterization techniques, inconsistent definitions of ITZ thickness and porosity, and the absence of standardized performance metrics. This review focuses primarily on structural LWAC produced with artificial and natural lightweight aggregates, with intended applications in high-performance civil engineering structures. This review systematically analyzes the microstructure, composition, and physical properties of the ITZ, including porosity, microhardness, and hydration product distribution. Quantitative data from recent studies are highlighted—for instance, incorporating 3% nano-silica increased ITZ bond strength by 134.12% at 3 days and 108.54% at 28 days, while using 10% metakaolin enhanced 28-day compressive strength by 24.6% and reduced chloride diffusion by 81.9%. The review categorizes current ITZ enhancement strategies such as mineral admixtures, nanomaterials, surface coatings, and aggregate pretreatment methods, evaluating their mechanisms, effectiveness, and limitations. By identifying key trends and research gaps—particularly the lack of predictive models and standardized characterization methods—this review aims to synthesize key findings and identify knowledge gaps to support future material design in LWAC.

In this study, seven Engineering Geopolymer Composite (EGC) groups with varying proportions were prepared. Rheological, compressive, flexural, and axial tensile tests of the EGC were conducted to study the effects of the water/binder ratio, the cement/sand ratio, and fiber type on its properties. Additionally, a uniaxial tension constitutive model was established. The results indicate that the EGC exhibits early strength characteristics, with the 7-day compressive strength reaching 80% to 92% of the 28-day compressive strength. The EGC demonstrates high compressive strength and tensile ductility, achieving up to 70 MPa and 4%, respectively. The mechanical properties of the EGC improved with an increase in the sand/binder ratio and decreased with an increase in the water/binder ratio. The stress–strain curve of the EGC resembles that of the ECC, displaying a strain-hardening state that can be divided into two stages: before cracking, the matrix primarily bears the stress; after cracking, the slope decreases, and the fiber predominantly bears the stress.

The Loess Plateau frequently endures droughts, and the propagation process has grown more intricate due to the interplay of climate change and human activities. This study developed the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Soil Moisture Index (SSMI) on a 3-month scale and examined the spatiotemporal characteristics and driving mechanisms of drought propagation from meteorological to agricultural drought utilizing cross-wavelet analysis, grey relational analysis, and the optimal parameter-based geographical detector (OPGD) model. The results demonstrate a substantial seasonal correlation between meteorological and agricultural droughts in spring, summer, and autumn, as evidenced by cross-wavelet coherence analysis (wavelet coherence > 0.8, p < 0.05). Lag analysis utilizing grey relational degree (>0.8) indicates that drought propagation generally manifests with a temporal delay of 1–3 months, with the shortest lag observed in spring (average 1.2 months) and the longest in winter (average 3.1 months). Distinct spatial heterogeneity is seen within geomorphological divisions: the loess wide valley hills and loess beam hills divisions exhibit the highest propagation rates (0.64 and 0.59), whereas the loess tableland and soil–stone hills divisions have lower propagation (around 0.50). The OPGD results reveal that precipitation, soil moisture, and temperature are the principal contributing factors, although their effects differ among geomorphological types. Interactions among components exhibit synergistic enhancement effects. This study improves our comprehension of seasonal and geomorphological heterogeneity in drought propagation from meteorological to agricultural droughts and provides quantitative evidence to support early drought warnings across various divisions, agricultural risk assessment, and water security strategies in the Loess Plateau.

Electric vehicles (EVs) have gained significant popularity globally during the past decade. This is mostly due to their reduced emissions of hydrocarbons and greenhouse gases. Electric vehicles acquire their electricity via wireless energy transmission, thereby circumventing the challenges associated with conventional techniques. The coils that transmit and receive signals deteriorate in performance and age as temperatures increase. Under extreme conditions, this may result in fire hazards and further safety issues. This article examined the electromagnetic and thermal dispersion of a magnetically coupled coil model for electric vehicles. This paper studied the electromagnetic and temperature distribution of the magnetically coupled coil model for electric vehicles. The coils were designed utilizing ANSYS software, with boundary conditions and pertinent parameters configured accordingly. The transmitter and receiver coils were identical in dimensions, with an inner diameter of 100 mm, an outer diameter of 295 mm, and an air gap of 60 mm between them. The magnetic coil was simulated and analyzed using copper as a material. In the aligned positions, the coupling coefficient between the transmitter and receiver coil was 0.168, its maximum temperature was 16.92 °C, and it was lower for the safety of the human body. An actual prototype was built to confirm the simulation results and to establish that the methodology employed in this research is applicable to the design of magnetic coils for a wireless charging system for electric vehicle models.

During severe drought conditions, water supply risks tend to be concentrated at critical water intake nodes and vulnerable river segments, while the conventional total balance method is inadequate for depicting the spatial evolution of these risks. This study developed a node-based water supply security assessment framework for the Feng River Basin, a representative watershed in the piedmont transition zone. The framework coupled SWAT-simulated runoff with a supply–demand balance model and evaluated water supply reliability at both the node and basin scales. Two scenarios were compared: an artificial water system scenario and an artificial water system with an engineering-based water resource allocation scenario. Dry (P = 75%) and extremely dry (P = 95%) conditions were considered to examine the performance of artificial regulation under drought stress. The results showed that basin-scale water supply reliability remained relatively stable, ranging from 0.833 to 0.853 under different scenarios. However, the node-scale results revealed strong spatial heterogeneity. Nodes 1 and 3 maintained full or nearly full reliability, whereas Nodes 4, 6, and 7 showed relatively low reliability and higher water shortage risk. Under the P = 75% scenario, engineering-based water resource allocation increased basin-scale reliability from 0.848 to 0.853, indicating a slight improvement in supply–demand balance. In contrast, under the P = 95% scenario, reliability decreased from 0.839 to 0.833 after introducing water resource allocation, suggesting that transfer-based interventions may have limited effectiveness when natural inflow is severely reduced. In particular, Node 7 showed a marked decline in reliability under the allocation scenario, indicating that water supply risks may be redistributed and concentrated at specific intake nodes under extreme drought conditions. The scenario comparison further indicates that water diversion strategies may produce a dual effect of local improvement and global reconfiguration. Insufficient supply intensity may result in engineering interventions that cause downstream water reduction impacts, leading to a spatial redistribution and shifting of risks rather than their systemic eradication. This study seeks to transition the evaluation paradigm from “total safety” to “node safety,” establishing a scientific foundation for enhancing the emergency response system in critical areas of the basin.

In this study, the optimal design of the central pipe in a middle-deep geothermal heat pump (MD-GHP) system is studied using the response surface method to improve the system’s coefficient of performance (COP) and operational reliability. Firstly, a model describing the energy transfer and conversion mechanisms of the MD-GHP system, incorporating unsteady heat transfer in the central pipe, is established and validated using field test data. Secondly, taking the inner diameter, wall thickness, and effective thermal conductivity of the central pipe as design variables, the effects of these parameters on the COP of a 2700 m deep MD-GHP system are analyzed and optimized via the response surface method. The resulting optimal parameters are as follows: an inner diameter of 88 mm, a wall thickness of 14 mm, and an effective thermal conductivity of 0.2 W/(m·K). Based on these results, a composite central pipe composed of high-density polyethylene (HDPE), silica aerogels, and glass fiber tape is designed and fabricated. The developed pipe achieves an effective thermal conductivity of 0.13 W/(m·K) and an axial tensile force of 29,000 N at 105 °C. Compared with conventional PE and vacuum-insulated pipes, the composite central pipe improves the COP by 11% and 7%, respectively. This study proposes an optimization-based design approach for central pipe configuration in MD-GHP systems and presents a new composite pipe with enhanced thermal insulation and mechanical performance.