The relevant literature on laser-MIG hybrid welding of aluminum alloy from the China National Knowledge Infrastructure (CNKI) core journal database and Google Scholar database in 2000-2023 was systematically analyzed by using VOSviewer. Three primary research focuses were identified by analyzing citation frequencies of key literature and the evolution of research hotspots: ① the interaction between laser and MIG heat sources, particularly the effects of laser-arc distance and heat source leading modes on plasma behavior and molten pool stability; ② hybrid welded joints, revealing the formation mechanisms and optimization strategies for defects such as porosity and cracks by investigation into morphological characteristics; ③ mechanical properties of welded joints, focusing on microhardness distribution and softening mechanisms in the heat-affected zone. Results indicate that the transition of Mg and other alloying elements can be effectively achieved by adopting welding wire alloying, and after heat treatment of those heat-treatable aluminum alloys, the welded metal exhibit remarkably enhanced strength and hardness through aging. The subsequent researches can employ multi-scale numerical simulations to explore the dynamic coupling mechanisms between laser and arc, and the interaction between droplet transfer and keyhole stability, as well as to optimize process parameters to suppress porosity and overcome the technical bottleneck in simultaneously improving welding speed and quality. This review can provide insights for enhancing the performance of laser-MIG hybrid welding of aluminum alloy.

The effect of Cr content in mass fraction on the microstructure and mechanical properties of Al-Cu-Mg-Ag alloy with a low Cu/Mg ratio was investigated. Results indicate that after an addition of Cr to the Al-Cu-Mg-Ag alloy with low Cu/Mg ratio, phases of Al-Cr and Al_1.6TiCr_0.4 are generated in the alloy; with Cr content from 0.17% up to 0.22%, the alloy has its tensile strength improved from 463 MPa to 484 MPa (a 4.5% increase), and its yield strength enhanced from 288 MPa to 319 MPa (a 10.8% increase). The enhancement in mechanical properties is attributed to solid solution strengthening by Cr and precipitation strengthening by S′ phases.

To gain an in-depth understanding of research status of ceramic additive manufacturing, the technical processes of direct ink writing, fused deposition modeling, selective laser sintering, stereolithography and digital light processing, as well as the materials used in those technologies are reviewed based on domestic and international researches on ceramic additive manufacturing. The advantages and disadvantages of those five technologies are summarized, which can provide references for their application scenarios. Finally, the prospect for the development of ceramic additive manufacturing is also discussed.

To study the motion characteristics of particles in hydraulic lift pipelines during deep-sea mining, a set of particle image processing technique was proposed, including image preprocessing, binarization processing, morphological operations, edge detection of particles, and overlapping segmentation. This technique was used to identify and extract particle information from cross-sectional images of pipe obtained from hydraulic transportation simulation experiments, and the distribution and motion patterns of particles within the pipeline were also analyzed. The results show that the larger particles tend to aggregate near the pipe wall, where fluid flows at a lower velocity; the smaller particles are mainly concentrated at the center of the pipeline with the fluid at a higher velocity. The distribution of the average particle velocity along the radial direction of the pipeline follows a parabolic law of variation. The average velocity decreases as particle size increases, and also the velocity reaches the maximum at the center of pipe and then gradually decreases towards the wall. It is found that the proposed particle image processing technique can be effective in analyzing the motion characteristics of particles in pipeline.

In order to conduct more practical stability analysis for soil-rock slope, it was proposed to use Fortran language in a slope model to randomly generate rocks, based on which a soil-rock slope model was established. The stability analysis was conducted respectively for soil-rock slopes with five kinds of rock content. It is found that as the rock content therein increases, the slope stability gradually improves and the potential sliding surface of the slope also changes. The plastic zone penetration presents three typical modes: rock detouring, shunting and rock inclusion. The displacement in X direction is always the largest at the foot of the slope, and the maximum total displacement starts at the foot, moving to the middle of the slope and finally back to the bottom of the slope. The simulation results obtained by this method were compared to the calculation results of models with two typical equivalent strength parameters, and it is concluded that the safety factor calculated by this method is quite different from that obtained by the other two models, and also different in changing trend. In the future, this soil-rock slope model can be further optimized for other complex working conditions based on the mechanical characteristics and laws, with the influence of joints and cracks also taken into consideration.

In the east side of Yanqianshan Iron Mine of Anshan Iron and Steel Company, the transition from open-pit to underground mining causes failure and collapse of rock slope. In order to solve this problem, tests were performed by adopting numerical simulation and the base friction model to analyze the failure process and failure mode. The different collapse angles at different mining stages were explored, and development process of collapse area was summarized in terms of fissures. It is found that as mining operation proceeds, the collapse angle is reducing due to disturbance of mining activity; the collapse area undergoes four stages, including progressive fissure enrichment, deformation during aging, growth of slip surface, and collapse formation; and the slope failure in the east side of Yanqianshan Iron Mine is predominantly attributed to the sliding crack model of deformation.

The traditional formula for prediction of blast-induced vibration has low accuracy, thus a prediction model for blast-induced vibration velocity in open-pit mines was constructed based on bidirectional long-short-term memory network (Bi-LSTM). This model can process time series data in both directions while capturing the dependency between inputs of the past and future information at upper and lower layers and the outputs. From the monitoring data of blasting operation in Gaocun Iron Mine of Maanshan Iron and Steel Group, the relevant data were selected as the inputs, and the prediction results by Bi-LSTM were compared with those based on Sadaovsky formula. The results show that the blast-induced vibration velocity predicted based on Sadaovsky formula has a mean error of 26.87%, and the blast-induced vibration velocity predicted by Bi-LSTM algorithm has a mean error of 8.95%. It is shown that the Bi-LSTM model can have the prediction results in a high degree of agreement with the measured results. In the future, this Bi-LSTM model will be trained with the monitoring data of other mines to improve its generalization ability, and also will be implanted by transfering learning into a real-time safety monitoring and early warning platform for mines.

In order to analyze the strength variation characteristics of cemented backfill mass at different temperatures under dynamic loading, a SHPB impact test was performed to study the mechanical properties of cemented backfill mass under dynamic loading during the energy evolution process. The results show that the compressive strength of the cemented backfill mass under dynamic loading increases as the curing temperature rises, and presents obvious splitting tensile failure. It is also found that the stress-strain curves of backfill mass at different curing temperatures are similar, all consisting of three stages: quasi-elastic stage, plastic deformation stage and post-peak failure stage. The backfill mass experiences a wave impedance effect. At an approximate strain rate (100 s^-1), about 77% of the energy is reflected and about 2% of the energy is transmitted through the backfill mass during the impact process. As the curing time is prolonged and the curing temperature rises, the energy absorption density and transmissive energy of the backfill mass increase. The micro-analysis shows that with the rise of curing temperature, the internal hydration reaction of backfill mass occurs at a higher rate, leading to higher degree of hydration and more hydration products. Those hydration products gradually fill in the internal pores of backfill mass, resulting in denser microstructure. It further confirms that increasing curing temperature can improve the early strength of backfill mass.

In order to scientifically assess risks in the production and operation of underground mines and improve the safety prevention and control in underground mining, a risk assessment index system for underground mines was constructed by selecting five primary indices and 16 secondary indices based on the underground mining characteristics. And then, the subjective and objective weights of the assessment indices were determined by using analytic hierarchy process (AHP) and entropy weight method (EWM), and the comprehensive weight of the indices was also optimized by adopting a combined weighting method to improve the accuracy of the assessment results. The safety risk in underground mines was assessed with the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). Later, five mines investigated by the experts organized by Hunan Bureau of the State Administration of Mine Safety were taken as samples for assessment with this method. The safety risk assessment results obtained with different models show that three risk indices with higher weights, including operation status of six equipment systems in terms of equipment factor, mine geological conditions in terms of environmental factor, and work safety system in terms of management factor, can bring obvious threat to the mine safety operation. The safety risk assessment of five mines shows that a tungsten mine has the highest risk level, while a graphite mine has the lowest risk level.

A beneficiation flowsheet comprised of two stages of roughing for copper-sulfur bulk flotation, bulk concentrate regrinding and Cu/S separation was adopted for optimization of beneficiation technique for a high-altitude copper ore. By applying asynchronous flotation for Cu-S bulk flotation and using KMY-1, a copper collector with good selectivity for Cu/S separation, efficient recovery of refractory copper minerals with microfine-grained dissemination can be actualized. A laboratory closed-circuit test finally produced a copper concentrate grading 23.06% Cu at 78.29% recovery, up by 2.92 percentage points and 9.59 percentage points correspondingly compared to the copper concentrate yielded from the on-site processing flow.