Calculation was made for four typical pipelines by adopting typical critical flow rate and frictional pressure drop calculation model. The precision of the model was analyzed by comparing the calculated value with the measured value of four pipelines. The results show that as for flow rate and pipe diameter, the calculated values from Wasp model, HAN Wenliang model, FEI Xiangjun model and LIU Dezhong model are in good agreement with the measured value, presenting the maximum deviation within the range of ± 15%. FEI Junxiang model presents higher precision in the calculation of frictional pressure drop, with the maximum deviation within the range of ± 10%, but also has certain margin in calculation. It is concluded that FEI Xiangjun model can provide an important basis and reference for the design of long-distance transportation.

A new directional core acoustic emission technique was used to measure in-situ stress of the gas storage reservoir construction area of the Zhangbei Comprehensive Energy Project in Hebei Province. Results show that three boreholes buried at depth of 90 m have the corresponding in-situ stress dominated by horizontal structural stress, with the maximum principal stress approximately in the same north-south direction. In addition, the circumferential wave velocity anisotropy analysis method was conducted for verification, and the results show that the maximum principal stress is in a direction consistent with the result obtained from the acoustic emission testing of borehole core, which further verifies the correctness of the measurement by acoustic emission technique for the borehole cores.

In order to obtain the information of landslide in forest area, a high-resolution digital terrain model was derived from LiDAR point cloud, and the data of landslide in forest area were extracted by Res-Unet network and persistent homology. The Fenghe Experimental Forest in Washington State of USA was selected for study, among which three areas were selected for quantitative analysis. Based on calculation, the extracted data of landslide in the forest area show an average precision of 79.7%, an average recall rate of 70.2%, and average F₁ of 65.5%. The extraction method based on Res-Unet and persistent homology can accurately identify most landslides in the research area. It is shown that by using deep learning and persistent homology, this extraction method can make up for the weakness of traditional remote sensing methods in extracting landslide information in vegetation covered areas, and also provide a technical support for landslide analysis.

Interrupted quenching experiments were conducted to investigate the hardness (HV) and unit initiation energy (UIE) of 7N65 alloy samples at various temperatures with different hold time, and the relative TTP-HV and TTP-UIE contour diagrams were also plotted. The precipitation behavior of second phases at various temperatures was characterized by adopting scanning electron microscope and transmission electron microscope. The findings reveal that S-phase (Al₂CuMg) is the dominant grain boundary precipitate after the alloy is held at a temperature between 390 ℃and 450 ℃, and increases in grain size and numbers as hold time is prolonged. Thus the alloy has less fracture toughness and is prone to fragile fracture along with the broken grains. When the alloy sample is held at a temperature between 250 ℃and 390 ℃, precipitates at grain boundaries are predominated by η-phase (MgZn₂), which increases in the numbers and grain size as hold time is prolonged, leading to lower strength of inner grain, smaller difference in strength between inner grains and grain boundaries. Thus, the alloy has higher fracture toughness and is more prone to ductile fracture with more transgranular dimples.

In order to effectively separate acid, arsenic and copper/zinc from smelting waste acid, a kind of simulated waste acid was taken to be treated by using electrodialysis with bipolar membrane. The effects of running time, acidity, initial concentration of arsenic and copper/zinc on the separation rate of acid, copper/zinc, and arsenic were investigated, and the process was also applied in the treatment of waste acid from copper smelting for verification. Besides, the surfaces of anion exchange membrane, cation exchange membrane and bipolar membrane in electrodialysis after long-term usage were analyzed and characterized. The results show that with the running time more than 80 min, arsenic concentration less than 9 g/L, acidity less than 5% and copper/zinc concentration less than 5 g/L, three kinds of solution respectively containing arsenic, valence metallic salt and acid were obtained. It is shown that the arsenic separation rate is more than 93%, the recovery rate of copper/zinc is more than 96%, and the recovery rate of acid is more than 97%. More than 90% of other metallic ions (such as Na, K, Mg, Ca) in waste acid are trapped in the bipolar membrane salt chamber, thus making inorganic salt ions effectively recovered from waste acid by an open circuit. After nearly two years of application, electrodialysis membrane and bipolar membrane are observed to have no obvious change in the apparent morphology, and no obvious precipitant attached on them.

The effects of different heat treatment processes on the microstructure and mechanical properties of RM80 steel were studied by means of scanning electron microscopy, Rockwell hardness tester and universal testing machine. As quenching temperature increases, carbides in RM80 steel gradually dissolve and the original austenite grains continue to grow. During tempering process, the structure of RM80 steel changes from tempered troostite to tempered sorbite, and martensite can still be observed in the structure of RM80 that is tempered after quenching at a higher temperature. After quenching at 1 150 ℃ and then three times of tempering at 550 ℃, RM80 steel finally has a good match between strength and plasticity, with a yield strength of 1 244 MPa, a tensile strength of 1 590 MPa, and an elongation of 12.0%.

The effects of different heat treatment regimes on the microstructure and properties of as-cast Mg-5Sn-1.5Al-1Zn-1Si alloy were investigated. The results indicate that during the dissolution of solid, as the dissolution time is prolongsed, the alloy dendrites gradually dissolve and the grains gradually spheroidize. It is shown that the appropriate dissolution parameter is 510 ℃ × 8 h, and the alloy after such treatment has an evenly distributed microstructure, with a trace of precipitation of fine second-phase particles from the matrix, and thus possesses a high elongation rate. The appropriate aging parameter for the alloy is 200 ℃ × 16 h, and due to precipitation and migration of the phases segregating at the grain boundary, the alloy after aging treatment possesses clear grain boundaries and a microstructure with high uniformity, and also has the yield strength up to 136.3 MPa, which is higher than that of the as-cast alloy by 16.5%. After a treatment including 8 hours of solid dissolution at 510 ℃ and 16 hours of aging at 200 ℃, the alloy has its uniformity and dispersion of the microstructure further improved, and its tensile strength and hardness reach to 178.2 MPa and 59.6HB, respectively, up by 21.6% and 23.4% compared to the as-cast alloy.

In order to solve the problem of high water content in JISCO iron concentrate, dewatering tests were conducted by adding filtration aid. The results show that the filtration aid, CYG-1, can improve filtration effect. With the addition of CYG-1 at an amount of 500 g/t, the water content in the filter cake of iron concentrate falls by 2.31 percentage points compared to the practice without adding filtration aid.

In Bangzhong Zinc-Copper Mine in Tibet, a mining method consisting of stoping followed by backfilling is adopted to excavate ores. In order to further improve production efficiency and economic benefits in the mine, rock mass quality was classified based on the investigation of geoengineering and geomechanics and rock mechanics test, and key factors influencing stability of stopes were analyzed in combination with the layout of mining and cutting engineering. On this basis, stope structure parameters were optimized by using a variety of empirical stability charts. The results show that the improved stability chart is highly adaptable and a stop with span extended from 12.5 m to 20 m can still meet safety requirement in the mining production.

The out-of-life saggar after repeated use for LiCoO₂ sintering in industry was taken to explore its erosion mechanism during high temperature synthesis of LiCoO₂ by adopting fluorescence analysis, chemical composition analysis, X-ray diffraction analysis, microstructure and energy spectrum analysis. Results show that when saggar is used to hold basic cobalt carbonate and lithium carbonate and calcined at 950 ℃ for 15 h, it is eroded and damaged after 15 times of operation. During LiCoO₂ synthesis, saggar is mainly eroded by lithium ions, with the dominant erosion products including tetragonal LiAlO_2, α-LiAlO_2, LiAlSiO_4, Li₃AlSiO₅ and Li_3.17Si_0.7S_0.3O_4. Cobalt ions are not involved in the chemical erosion but the synthesized lithium cobalt compounds migrate along the pores and also deposit along the migrating pores of saggar.