Civil unmanned aerial vehicles (UAVs) serve increasingly diverse applications, yet their technological structure, evolutionary pathways, and future trends remain difficult to characterize. This study analyzes global civil UAV invention patents from the PatSnap database (2005–2024) by integrating BERTopic-based topic identification, semantic–intensity-coupled evolution analysis, and self-attention-enhanced long short-term memory (SA-LSTM) forecasting. Of 61,715 screened patent records, 59,217 texts remained for topic modeling after deduplication by application number and removal of records with missing or invalid text. We identify 30 technology topics grouped into nine categories and distinguish three stages of development: foundational platform development, intelligent capability enhancement, and networked system development. Four major pathways are revealed: from single-UAV stability control to swarm intelligence; from lithium-ion batteries to alternative energy systems and automated replenishment; from point-to-point communication to networked low-altitude systems; and from single-mission applications to integrated multi-scenario operations. Forecasts for 2025–2029 indicate heterogeneous topic trajectories, suggesting development potential in low-altitude communication networks, swarm control, and emerging power systems. Together, these findings provide patent-based evidence to support technology monitoring, screening of candidate R&D directions, and planning of subsequent engineering assessments.
Against the background of the “Dual Carbon” strategy, adopting energy-saving conductors is a vital measure to reduce transmission line losses and carbon emissions. In this paper, an AC resistance test platform is built to characterize the AC resistance and temperature-rise features of conventional ACSR and three energy-saving conductors. Typical main transmission lines and tie-lines in Chongqing are selected as engineering cases to compare their transmission capacity, line loss and CO2 emission reduction performance. The results demonstrate that JLHA3 has the lowest AC resistance and the greatest potential for loss and carbon reduction, yet its high incremental investment weakens its economic competitiveness under the adopted carbon price scenario. JL3/G1A strikes a good balance between incremental investment and energy-saving benefits, making it the economically favorable option for high-utilization main supply lines. For tie-lines with low annual utilization hours, only JL3/G1A remains economically viable among the three energy-saving conductors, although its economic margin is narrow; JLHA3 and JL3/LHA1 fail to recover their additional construction costs over the whole service life cycle. This study can support hierarchical conductor selection and the low-carbon retrofit of transmission lines.
Ball mills are energy-intensive units whose performance depends strongly on internal charge dynamics, which are difficult to observe directly. This mini-review analyzes the six studies on instrumented balls identified in our literature search, which was conducted without temporal restrictions. The six identified studies were published between 1978 and 2021. The reviewed works show an evolution from impact-force measurement devices to sensorized grinding media used for dynamic analysis, DEM validation, wet-grinding studies, and mill-load classification. The comparison highlights advances in sensing, mechanical design, data handling, and signal interpretation, while also identifying persistent barriers to industrial use, especially mechanical representativeness, durability, data retrieval, and reliable communication through the mill shell. Future opportunities include wear-state estimation, soft sensing of internal process variables, slurry chemistry sensing, and integration with monitoring and control systems. Overall, instrumented balls are promising tools for improving the understanding, modeling, and supervision of ball mill operation.
To address the complexity of the crankshaft structure in reciprocating air compressors and the high cost of prototype testing, a scaled-model design method for reproducing torsional natural-frequency characteristics is proposed based on dynamic similitude theory. Taking the crankshaft of a certain air compressor as the research object, its lumped parameter model is established and the differential equation of vibration is derived. The similitude relation for torsional natural frequency is derived using the equation analysis method, and the preservation of the retained global torsional mode shapes during model condensation is quantitatively evaluated using the Modal Assurance Criterion (MAC). By preserving the prescribed rotational inertias and torsional stiffnesses, the crankshaft system is transformed into a three-dimensional model consisting of disks and elastic shafts, and a scaled model is designed according to the similitude criteria. Finite element modal analysis compares the natural frequencies of the equivalent three-dimensional model and the scaled-down model, showing agreement with the theoretical similitude predictions. A scaled-model test rig is constructed to provide limited experimental frequency-domain evidence for the first predicted frequency characteristic. The experimentally observed frequency component consistent with the first predicted torsional natural-frequency characteristic differs from the theoretical value by 0.55%; however, this deviation is not interpreted as a quantified measure of predictive accuracy. The experiment provides only partial supporting evidence for the proposed design procedure; the second torsional natural frequency, modal shapes of the scaled physical model, modal mass, modal stiffness, and modal damping are not independently validated experimentally in the present study. The results indicate that the proposed similitude design method can reproduce the torsional natural-frequency characteristics investigated in this study with a reduced model size, and may provide a potential approach for investigating the torsional natural-frequency characteristics of crankshaft-type systems, subject to system-specific recalculation and further validation.
This study presents the concept design of a wireless-controlled powered transport chair for caregiver-assisted handling and short-duration seated movement in care facilities. No prototype has been fabricated and no structural, metrological, or human testing has been performed; every value reported is a design requirement, not a measured result. The intended users are adult patients who tolerate supported sitting and retain enough trunk control to remain seated with the support rails and restraint engaged, together with a trained caregiver; patients needing full postural support or a lying transfer are outside the intended use. The device integrates powered low-speed mobility, height adjustment, a powered fore–aft seat extension that bridges the residual gap left at the bed base, local and wireless control, an independent hardwired emergency stop, and load-cell seated weight measurement. The frame is designed to accommodate a patient of up to 150 kg. A Raspberry Pi provides the user interface, while an independent hardware layer governs all powered motion. Candidate frame materials are compared qualitatively. Verification covers proof-load testing, worst-case static stability, load-cell calibration, control and emergency-stop response, power-loss recovery, battery endurance, and usability testing with caregivers and patients. Participatory design with wheelchair users and caregivers is planned before fabrication.
