Tebian Electric Apparatus (China)

This study investigates the sulfate durability performance of concrete incorporating lead-zinc tailings sand (LZTS) as partial replacement for fine aggregates. Greater emphasis is placed on long-term resistance to sulfate attack rather than on strength enhancement, ensuring full consistency with the manuscript title. Sulfate exposure conducted in a 5% Na2SO4 solution for periods of up to 180days, during which mass change, linear expansion, surface degradation, and residual mechanical strength were systematically evaluated. The results demonstrate that optimized levels of LZTS replacement, in combination with low-dosage hybrid nanomaterials, significantly enhance the sulfate resistance while maintaining satisfactory mechanical performance. From a sustainability perspective, replacement of up to 50% of natural river sand is achievable, contributing to reduced depletion of natural resources. Microstructural observations obtained from SEM, supported by XRD and FTIR analyses, provide indirect yet consistent evidence of matrix densification and suppression of sulfate reaction products. FTIR spectra confirmed these observations by intensifying Si-O-Si and Al-O-Si bands and weakening Sulfate-associated vibrations with Heavy metal immobilization efficiency exceeding 90%. The findings reveal the potential of LZTS-based concrete as a durable and environmentally responsible construction material for sulfate-rich environments.

DC-GIL insulators are key components that provide both electrical insulation and mechanical support. However, their insulation and mechanical designs have traditionally been developed separately, without accounting for the influence of mechanical stress on insulation breakdown. This study investigates how mechanical stress affects the breakdown strength of epoxy/Al<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> composite samples at various temperatures. Results show that breakdown strength decreases significantly with increasing mechanical stress, and this effect becomes even more pronounced at elevated temperatures. The security region of DC-GIL insulators can be defined as the region bounded by the breakdown-strength (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub>) and tensile-strength (σ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub>) intercepts on the coordinate axes. Accordingly, the criterion <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E/E</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> + σ/σ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> < 1 can be used to assess the safety margin of DC-GIL insulators.

The synchronization stability of grid-connected inverters is crucial for the reliable operation of renewable energy system. It is found in this article that under weak grid conditions, as the increase of active power, the inverter is prone to collapse due to phase locking failure when the output reactive power is insufficient. The reason lies in the positive feedback loop in the phase-locked loop. An increase in the active power and a decrease in reactive power can both lead to the expansion of the positive feedback effect and even result in the collapse of the phase-locked loop. A frequency deviation-based feedforward control strategy is proposed in this paper, which can weaken the response of the positive feedback loop and enhance the synchronization stability. Finally, the simulation results verify the theoretical analysis.

High-end manufacturing sectors such as aerospace, marine vessels, rail transportation, energy power, and information electronics impose extremely demanding requirements on manufacturing technologies, and face challenges including multi-variety production, small batch sizes, high reliability, high consistency, and complex manufacturing processes. Meanwhile, production anomalies occur throughout the entire manufacturing flow, and traditional anomaly management methods—plagued by data fragmentation, delayed feedback, and inflexible scheduling—are increasingly inadequate to meet the practical needs of high-end equipment manufacturing. To address this bottleneck, a framework of digital-intelligent anomaly control in the design and manufacturing of high-end equipment is proposed. This framework establishes a key technological system for a collaborative closed loop of “design-scheduling-control” tailored to complex manufacturing requirements, which includes: a large language model(LLM)-driven design approach; a knowledge- and data-fusion driven proactive-reactive scheduling method for smart workshops; and a cloud-edge-device collaborative digital twin control method. By reshaping conventional anomaly management processes through digital-intelligent technologies, this model effectively supports flexible production and high-precision control in multi-variety, small-batch manufacturing scenarios, thereby enhancing the batch production capability of complex products.

Aiming at the problem of complex background interference and insufficient weld detection accuracy in steel structure weld recognition task, this paper proposes a target detection algorithm based on improved YOLOv5. By introducing the Coordinate Attention (CA) mechanism in the backbone network and integrating the CA with the C3 structure, the C3CA module is designed to effectively enhance the model’s perception of the spatial position of the weld and the detection accuracy of the weld. Experiments show that the improved YOLOv5s-C3CA model achieves 93.79% mAP@0.5 on the self-made weld data set, which is 2.48% higher than the original model. At the same time, the amount of model parameters is reduced by 8.53%, and the floating point operation is reduced by 10.6%, which achieves a balance between detection accuracy and calculation efficiency. This study verifies the effectiveness of the coordinate attention mechanism in improving the feature expression ability of the model, and provides a solution for the automatic detection of welds in industrial scenarios.