Gezhouba Group (China)

ABSTRACT This paper investigates the combined effects of corrosion and alternating stress on the corrosion fatigue (CF) life of high‐strength steel wires (HSSWs). An extensive dataset of CF samples for HSSWs is presented, considering stress range, cyclic loading frequency, and potential difference as influencing factors. A generalized probabilistic model is developed to predict the CF life of HSSWs by exploring the combined effects of these factors. The results indicate that the proposed model accurately fits the CF samples and effectively predicts the CF lives of HSSWs with a specified survival probability. At higher stress ranges, CF life initially increases but then decreases as the potential difference rises, indicating a competing interaction between corrosion and fatigue mechanisms. The CF lives of HSSWs are particularly sensitive to lower stress ranges, lower cyclic loading frequencies, and higher potential differences. Notably, the effect of cyclic loading frequency becomes negligible when it exceeds 10 Hz.

ABSTRACT Caculo Cabaça is a newly identified site located in the middle course of the Cuanza River in Angola documenting an extended human settlement dated to the 15th century a.d. It displays the earliest known evidence of dry-stone architectural practices in central Angola, including tumuli, stone platforms, and wall foundations. We present the first series of radiocarbon dates recovered from burial contexts, including the only known archaeological cremation in Angola to date. Results present the architectural diversity of the Caculo Cabaça archaeological complex along with the associated ceramic assemblages and the characteristics of the human burials. Finally, our results highlight a spatially dynamic interaction between funerary, domestic, and iron production practices in the Middle Cuanza River landscape, contributing new archaeological insights into the cultural complexity of south-central Africa prior to the colonial period.

This paper proposes a 3D-SIP precise simulation design method for system in package design of highly integrated RF Circuits, Precise simulation design is carried out using multiple methods such as three-dimensional circuit simulation, full-wave electromagnetic field simulation, and co-simulation. A high-performance L-band receiver SIP with local oscillator is successfully designed, and the measurement results verify the effectiveness of the design method.

Traditional centralized highway energy systems exhibit significant resilience shortcomings in the face of climate change mitigation requirements and increasingly frequent extreme weather events. Meanwhile, prevailing microgrid control strategies remain predominantly focused on economic optimization under normal conditions, lacking the flexibility to address dynamic risks or the interdependencies between transportation and power systems. This study proposes an adaptive, risk-driven control framework that holistically coordinates power generation infrastructures, microgrids, demand-side loads, energy storage systems, and transport dynamics through continuous risk assessment. This enables the system to dynamically shift operational priorities—from cost-efficiency in stable periods to robustness during emergencies. A multi-objective optimization model is established, integrating infrastructure resilience, operational costs, and traffic impacts. It is solved using an enhanced evolutionary algorithm that combines the non-dominated sorting genetic algorithm II with differential evolution (NSGA-II-DE). Extensive simulations under extreme weather scenarios validate the framework’s ability to autonomously reconfigure operations, achieving 92.5% renewable energy utilization under low-risk conditions while elevating critical load assurance to 98.8% under high-risk scenarios. This strategy provides both theoretical and technical guarantees for securing highway renewable energy system operations.

Crushed sand is becoming a main substitute for river sand in the concrete industry. The quality of crushed sand production is crucial for concrete. Fine powder refers to the particles less than 0.075 mm in crushed sand, mainly consisting of rock powder (limestone with CaCO3 as the main component) from the parent rock, and clay powder (yellow clay with Al2(Si2O5)(OH)4 as the main component) from the clay minerals. These particles possess a strong adsorption effect, significantly impacting the performance of high-fluidity concrete. This study addresses the issues of distinguishing and optimizing the content of each component in the fine powder of crushed sand used for preparing high-fluidity concrete. To this end, a method has been established to determine the content of each component based on the methylene blue value (MBV). Furthermore, rational content classifications based on MBV have been proposed through a series of tests on crushed sand mortar, including rheological properties, workability, strength, and scanning electron microscopy (SEM) analysis. Finally, a correlation has been established between the initial yield shear stress and the slump flow of mortar, which can be used to predict the workability of mortar and provide guidance for controlling the fine powder content.

This paper investigates the nonlinear dynamics of the wheel-side planetary reducer, considering the tooth wear effect. The tooth wear model based on the Archard adhesion wear theory is established, and the impact of tooth wear on meshing stiffness and piecewise-linear backlash of the planetary gear system is discussed. Then, the torsional vibration model and dimensionless differential equations considering tooth wear for the wheel-side planetary reducer are established, in which meshing excitations include time-varying mesh stiffness (TVMS), piecewise-linear backlash, and transmission error. The dynamic responses are numerically solved using the fourth-order Runge–Kutta method. On this basis, the nonlinear dynamics, such as the bifurcation and chaos properties of the wheel-side planetary reducer with tooth wear, are analyzed. Simulation results demonstrate that the existence of tooth wear reduces meshing stiffness and increases backlash. The reduction in the meshing stiffness changes the bifurcation path and chaotic amplitude of the system, inducing chaotic phenomena more easily. The increase in the gear backlash causes a higher amplitude of the relative displacement and more severe vibration.

Fly-ash-based bubble lightweight soil is widely used due to its environmental friendliness, load reduction, ease of construction, and low costs. In this study, 41 sets of 28 d compressive strength data on lightweight soils with different water–cement ratios, blowing agent dosages, and fly ash dosages were collected through a literature search and indoor tests. Using the compressive strength index and SEM tests, the correlation between the mix ratio design and the microscopic particle components was investigated. The findings were as follows: carbonation reactions occurred in lightweight soil during the maintenance process, and the particles were spherical; increasing the dosage of blowing agent increased the soil’s porosity and pore diameter, leading to the formation of through-holes and reducing the compressive strength and mobility; increasing the fly ash dosage and water–cement ratio increased the soil’s mobility but reduced its compressive strength; and the strength decreased significantly when the fly ash dosage was more than 16% (e.g., the strength at a 20% dosage was 17.8% lower than that at a 15% dosage). Feature importance analysis showed that the water–cement ratio (57.7%), fly ash dosage (30.9%), and blowing agent dosage (11.1%) had a significant effect on strength. ExtraTrees, LightGBM, and Bayesian-optimized Random Forest models were used for 28d strength prediction with coefficients of determination (R2) of 0.695, 0.731, and 0.794, respectively. The Bayesian-optimized Random Forest model performed optimally in terms of the mean square error (MSE), root mean square error (RMSE), and mean absolute error (MAE), and the prediction performance was best. The accuracy of the model is expected to be further improved with expansions in the database. A 28 d compressive strength prediction platform for fly-ash-based bubble lightweight soil was ultimately developed, providing a convenient tool for researchers and engineers to predict material properties and mix ratios.

The anchor cables of slopes are affected by long-term environmental corrosion, geotechnical creep, and adverse weather, resulting in gradual loss of tensile force, which can lead to structural failure and subsequent safety accidents. The authors of this paper conducted research based on the magnetic induction density distribution characteristics of permanent magnets, including model derivation, theoretical simulation, and indoor experiments, aiming to propose a new anchor cable force monitoring technology with high sensitivity, strong applicability, and good stability. Based on the molecular circulation model and the Biot–Savart law, the analytical expression of the spatial magnetic field distribution of a rectangular permanent magnet was derived and, combined with the stress–strain relationship characteristics of anchor cables, a theoretical model for the relationship between anchor cable tensile force and magnetic induction density was established. MATLAB (R2018b) was used to simulate and analyze the spatial magnetic field distribution and the force–magnetism relationship. The analysis showed that the magnetic induction density along the central axis of the permanent magnet approximately exhibited a symmetrical quadratic curve distribution, and its value was significantly negatively correlated with the anchor cable force. Based on this, a new anchor cable force monitoring technology was proposed, and an indoor experimental platform was established. The indoor experimental studies further confirmed the negative correlation between force and magnetism (i.e., as the tensile force increases, the magnetic induction strength decreases, and as the tensile force decreases, the magnetic induction strength increases). The fitting results of the force–magnetism curve show that a quadratic function can better describe the correspondence between magnetic induction density and anchor cable force. Reproducibility analysis of the experimental data showed low dispersion in magnetic induction values under various design loads, along with good stability, validating the effectiveness and applicability of the proposed anchor cable force monitoring technology.