Nihed Allouche, Bouzid Boudjema, Radouane Daira
et al.
Carbon dioxide sensors are crucial for industrial processes and monitoring indoor air quality, but developing low-cost, high-performance sensors that operate at room temperature remains challenging. This study explores carbon dioxide detection using copper oxide thin films doped with sodium (CuO:Na), barium (CuO:Ba), erbium (CuO:Er), and vanadium (CuO:V), which were fabricated through spin-coating and annealed at 500 °C. All the films displayed a monoclinic tenorite structure, with crystallite sizes ranging from 23.8 to 59.5 nm, and band gaps that increased from 1.7 eV for pure copper oxide to 2.1 eV for copper oxide doped with vanadium (CuO:V). Among the various sensors, copper oxide doped with vanadium (CuO:V) exhibited the best performance, with a 248.3% response to 11100 ppm carbon dioxide at 30 °C and 45% relative humidity. It also had a response time of 7.4 s and a recovery time of 7.5 s. At 25% relative humidity, the response improved to 401.2%, reaching 1220% at 140 °C and 45% relative humidity. These findings highlight the potential of copper oxide doped with vanadium (CuO:V) for energy-efficient carbon dioxide detection, offering valuable contributions to environmental monitoring and efforts to mitigate climate change.
During the large-scale development of deep coalbed methane in the Daji block on the eastern edge of Ordos Basin, using horizontal wells combined with large-scale volume fracturing, some wells experienced fracturing interference under similar fracturing techniques and technical parameters, significantly affecting the fracturing transformation and gas production outcomes. Through precise 3D seismic interpretation in the early stage, it was found that faults were not developed in the block, suggesting that the development of local micro-scale fractures might be a significant factor causing fracturing interference in horizontal wells. Focusing on the deep No. 8 coal seam in the study area, we rely on high-quality 3D seismic data characterized by “two wide and one high” features. Through OVT （Offset Vector Tile）domain processing, we obtained five-dimensional seismic data encompassing time, space (3D coordinates), offset (or source-receiver distance), and azimuth. For the first time, we employed azimuthal statistics to investigate the development degree, orientation, and developmental stages of micro-scale fractures. The research findings indicate that micro-scale fractures are generally well-developed in the study area, with five major fracture zones observed, and the degree of micro-scale fracture development is higher in the southern part compared to the northern part. The development of fractures is controlled by two phases of regional tectonic activity, exhibiting two distinct planar distribution directions. Specifically, fractures oriented in the near EW and NW directions were formed during the Yanshanian tectonic activity, while fractures oriented in the near SN and NE directions were formed during the Himalayan tectonic activity. By integrating regional tectonic stress fields from different periods, field outcrops, imaging logging, and array sonic logging data, we verified the reliability of our research findings on the degree and direction of fracture development. Applying these micro-fracture prediction results guided the optimization and implementation of the horizontal well fracturing plan in the study area in later stages, leading to a significant reduction in the interference ratio from 14.58% in 2023 to 5.23%. Meanwhile, statistics show that the average daily gas production for wells put into production in 2023 was 6.7×104 m3, and for wells put into production in 2024, it was 7.5×104 m3, indicating a significant reduction in fracturing interference and a continuous improvement in development effectiveness. This prediction method can provide valuable insights for predicting micro-scale fractures in deep coalbed methane blocks with similar geological conditions.
Here, we report a soft magnetic nanocrystalline alloy with high electric resistivity (<i>ρ</i>) up to 221 μΩ·cm. The (Fe<sub>82</sub>Si<sub>3</sub>B<sub>14</sub>Cu<sub>1</sub>)<sub>100−x</sub>Ca<sub>x</sub> (x = 0, 0.12, 0.36, and 0.6) alloys were prepared by melt spinning. The effects of Ca addition and annealing treatment on the microstructure and properties of the alloys have been investigated. It was found that Fe<sub>82</sub>Si<sub>3</sub>B<sub>14</sub>Cu<sub>1</sub> alloys without Ca doping contain mainly one nanocrystalline phase of α-Fe, but both α-Fe and Fe<sub>3</sub>B nanophases coexist in the as-prepared alloys with relatively high Ca contents (x = 0.36 and 0.6) and annealed Ca co-doped alloys. The presence of Fe<sub>3</sub>B nano-crystals leads to high resistivity without significantly reducing the soft magnetic properties. The saturated magnetic induction <i>B</i><sub>s</sub> of (Fe<sub>82</sub>Si<sub>3</sub>B<sub>14</sub>Cu<sub>1</sub>)<sub>100−x</sub>Ca<sub>x</sub> (x = 0, 0.12, 0.36, and 0.6) alloys ranges from 1.75 T to 1.80 T, and the coercivity <i>H</i><sub>c</sub> of annealed alloys shows a tendency to increase with an increase in Ca content. Meanwhile, the resistivity of both as-prepared and annealed alloys increases with increasing Ca content. The as-prepared (Fe<sub>82</sub>Si<sub>3</sub>B<sub>14</sub>Cu<sub>1</sub>)<sub>99.4</sub>Ca<sub>0.6</sub> alloy exhibits an excellent combination of soft magnetic properties with <i>ρ</i> = 221 μΩ·cm, <i>H<sub>c</sub></i> = 20.3 A/m, and <i>B</i><sub>s</sub> = 1.57 T. After annealing, these values changed to 158 μΩ·cm, 21.6 A/m, and 1.79 T, respectively. We believe that this work is helpful for developing nanocrystalline soft magnetic alloys for high-frequency applications.
The shape of the blast casting muck pile in surface coal mines is an important factor that affects the operational efficiency and cost of the blast casting pulling shovel stacking process system. In order to improve the accuracy of predicting the shape of blast casting muck piles in surface coal mines, further optimize the design of blast casting, and reduce the cost of blast casting stripping, based on the measured data of blast casting in the Heidaigou surface coal mine, an example analysis was conducted. The entropy method grey correlation method was used to study the weight and correlation between the impact indicators of blast casting effect and the farthest throwing distance, looseness coefficient, and effective throwing rate. The correlation between hole spacing, section width and the evaluation indicators of blast casting effect is relatively low. The minimum resistance line, row spacing, explosive consumption, step height, lower mouth width of goaf, slope angle, and upper mouth width of goaf were selected as input parameters for the prediction model. The Gaussian distribution model was introduced to simulate the profile curve of the blast casting muck pile. By using a 1–8th order Gaussian distribution model to simulate and analyze the detonation profile curve, it was determined that the simulation accuracy and efficiency reach an optimal level when the order is 5. The trained HHO–LSSVM was used to predict 15 parameters of the 5th order Gaussian distribution model, which were used as the control parameters for predicting the output detonation shape. And the Gaussian distribution model combined with the HHO–LSSVM algorithm was used to predict the shape of the blast casting muck pile, compare the accuracy of the LSSVM, Particle Swarm Optimization (PSO) optimized Least Squares Support Vector Machine, and Genetic Algorithm (GA) optimized BP neural network models, at the same time, compare the predicted blast casting muck pile morphology with the actual blasting muck pile morphology. The results show that the sum of squared errors (S) parameter of the blasting muck pile morphology curve simulated using a 5th order Gaussian distribution tends to stabilize at 25.69, and the coefficient of determination (R2) and adjusted coefficient of determination (\begin{document}$R_{\mathrm{A}}^2 $\end{document}) are 0.999 2 and 0.999 0, respectively. The root mean square error (R) is 0.514 6. The prediction error of the HHO–LSSVM for the 5th order Gaussian distribution control parameters is mostly around 1%, and the error does not exceed 5%, compared with the LSSVM, PSO, and GA–BP algorithm models, the accuracy is higher. Taking the profiles E5–8, E5–9, and E5–10 as examples, the errors R2 and R between the predicted and actual detonation morphology are 0.998 7 and 0.614 2, 0.999 2 and 0.493 1, 0.999 2 and 0.505 2, respectively, the predicted shape of the blasting muck pile is close to the actual shape of the blasting muck pile morphology.
Rehan Khan, Michał Wieczorowski, Abdel-Hamid I. Mourad
et al.
Erosion behavior of AISI 1045 carbon steel was investigated using slurry solutions with different viscosities (1 cP, 3 cP, and 8 cP) containing 5 wt% silica sand as erodent particles. Tests were carried out using a slurry pot apparatus with various rotational velocities and at three mounting angles (30°, 60°, and 90°). The qualitative and quantitative analysis was performed using the Taguchi design method, paint modeling, image processing, and microscopic imaging techniques. The results indicate that the erosion process in the slurry flow is significantly influenced by fluid viscosity. There is a notable decrease in erosion wear rate as fluid viscosity increases. An analysis of variance (ANOVA) test was conducted, concluding that viscosity and rotational speed are the significant factors influencing the weight loss of carbon steel. The results demonstrate that each factor has a major impact on the response; velocity (47.20 %) is the primary factor contributing to R, followed by viscosity (38.20 %). The erosive wear mechanism changed considerably with the variation in fluid viscosity and impact angles. As viscosity increases, the cutting and pitting erosion wear mechanism shift to sliding wear with the development of micro-perforation sites.
Wenming Tang, Xianxian Zhang, Jianfeng Tang
et al.
The common neighbor analysis (CNA) for binary systems is a powerful method used to identify chemical ordering in intermetallics by unique indices. The capability of binary CNA, however, is largely restricted by the availability of indices for various ordered phases. In this study, CNA indices of 11 ordered phases derived from a face-centered cubic structure were introduced on a case-by-case basis. These phases, common in intermetallics containing platinum-group metals, include C11<sub>b</sub>, MoPt<sub>2</sub>, C6, B11, AgZr, A<sub>2</sub>B<sub>2</sub>[111], A<sub>2</sub>B<sub>2</sub>[113], Pt<sub>3</sub>Tc, A<sub>3</sub>B[011], A<sub>3</sub>B[111], and A<sub>3</sub>B[113]. The chemical order in static chemical perturbation, dynamic phase competition, and experimentally reconstructed nanophase alloys were identified using binary CNA. The results indicated that the proposed version of binary CNA exhibited significantly higher accuracy and robustness compared to the short-range order, polyhedral template matching, and the original binary CNA method. Benchmarked against available methods, the formation, decomposition, and competition of specifically ordered phases in bulks and nanoalloys were well reflected by present CNA, highlighting its potential as a robust and widely adopted tool for deciphering chemical ordering at the atomic level.
Carbon emission from the coal-burning power plant is the main source of CO2 emitted in the China’s energy industry. Biomass power generation is deemed to be a carbon-neutral or even carbon-negative mode. Therefore, the development of coal coupled biomass gasification technology for power generation can help to achieve a coal substitution and carbon emission reduction and is a realistic and feasible path for maintaining a low-carbon coal power generation. In this context, an overview of three coal coupled biomass power generation technologies (the coal/biomass direct combustion of coal and biomass, the coal/biomass direct combustion coupled in parallel mode, and the coal direct combustion coupled with biomass gasification) has been conducted in this study. The characteristics of the above three technologies have been analyzed. Future development trends in the coal-burning coupled biomass gasification power generation technology have been put forward. The physicochemical adaptability of the feedstock and the influence of the feedstock on the gasifier are also studied based on the coupled gasification power generation technology. This work has emphasized the technological process of coal coupled biomass gasification power generation technology, including biomass transportation system, gasifiers (the technical characteristics, technical challenges and development direction of circulating fluidized bed gasifier (CFB), double fluidized bed gasifier (DFB), downdraft fixed bed gasifier, updraft fixed bed gasifier, crossdraft fixed bed gasifier and chain grate have been analyzed), gas cooling system, gas-pressurized transportation system, combustion system and gas purification system. The energy utilization efficiency analysis, economic analysis and environmental benefit analysis of the technology have been carried out. The analysis obtained would provide a theoretical reference and technical support for the research and application of coal-coupled biomass power generation technology. In addition, a series of national policies to promote coal coupled biomass gasification power generation technology and the current successful cases of coal coupled biomass gasification power stations are also presented. Finally, the challenges and future development of coal coupled biomass power generation technology have been prospected.
This work presents the comprehensive and comparative study on microstructures and properties (including morphology, composition, phase structure, electrochemical performance, etc.) of the iridium oxide-tantalum oxide (IrO2–Ta2O5) coated titanium (Ti) anodes prepared by novel microwave plasma-assisted sintering (MPAS) and conventional thermal decomposition (CTD) methods. To characterize and evaluate these anodes, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), and electrochemical tests are employed. The results demonstrate that the surfaces of the anodes prepared by CTD and MPAS at 500 °C have “mud cracks” with the latter having more, but the anode prepared by MPAS at 600 °C does not present any crack, and the surface is spongy and porous. Compared with the anode by CTD method, the total pore area of the coating prepared by MPAS at 600 °C decreases obviously, from 2.124% to 0.908%. Meanwhile, the coating prepared by CTD has more high valence species and oxygen vacancy defects. Metallic iridium, amorphous iridium oxide or fine crystallites of rutile IrO2, and low-valent Ta oxides will be formed on the electrode surface treated by MPAS. In addition, the onset potentials of oxygen evolution reaction (OER) of the anodes by MPAS methods (1.15–1.16 V) are much lower than that of the anode by CTD process (1.21 V). The voltammetric charge of the anode prepared by MPAS at 500 °C is nearly four times that of the anode by CTD method. The oxide anodes fabricated by MPAS method demonstrate very large electrochemically active surface area and excellent electrocatalytic activity of OER, but show inferior stability that should be further improved.
The performance of coke in blast furnace has higher requirement under the carbon emission peak & carbon neutrality goal and hydrogen-rich blast furnace development in China. Except for the thermal performance, the lump size of coke gets more attention. The pyrolysis shrinkage of coking coal is an important factor to determine the lumping performance of coke. The coking tests of coal with different deterioration were carried out with 2 kg coke oven, the effect of fineness of coal on coke lumping property was analyzed. An improved Audibert-Arnu dilatometer was used to study the shrinkage performance of eight kinds of coking coals with different degrees of metamorphism during the pyrolysis process at 300 ℃ to 900 ℃. The influence of the shrinkage coefficient of coal pyrolysis and its shrinkage dynamic characteristics on the caking performance of coke was discussed, and the mathematical relationship between the shrinkage coefficient of pyrolysis and the activation energy of pyrolysis of the average caking size of coke was established. It attempts to predict the average lumpiness of coking coal by its pyrolysis shrinkage characteristics. The results show that the average lumpiness of coke is increased with the increase of coking coal metamorphism. The average lumpiness of YK gas coal is only 38.9 mm, while the SAJ coking coal and BBG lean coal are 50.5 mm and 48.5 mm respectively. Among the eight kinds of coking coals, except for BBG lean coal, the average lumpiness of coke formed is the largest when the fineness of coal into furnace is 75%. The average lumpiness of coke is the best when BBG lean coal is 85% in fineness. On the pyrolysis process, the shrinkage coefficient and activation energy of the first shrinkage peak of coking coal with different metamorphic degrees are obviously different. The pyrolysis shrinkage coefficient of low-metamorphic YK gas coal and SYS1/3 coking coal is higher than 8.33×10−4 ℃−1, and the pyrolysis activation energy is lower than 77 kJ/mol. The pyrolysis shrinkage coefficient of LH coking coal, SAJ coking coal and BBG lean coal is lower than 4.55×10−4 ℃−1, but the activation energy required for pyrolysis is all higher than 106.1 kJ/mol. It indicates that the coking coal with high metamorphism requires higher energy to complete the shrinkage process during pyrolysis. The larger the shrinkage coefficient of coking coal, the smaller the average lumpiness of coke, and the pyrolysis shrinkage coefficient has a good linear relationship with the average lumpiness of coke, the correlation coefficient is 0.90. At the same time, the activation energy of pyrolysis shrinkage is also closely related with the average lumpiness of coke. Therefore, pyrolysis shrinkage coefficient and shrinkage activation energy can be used to effectively predict the average lumpiness of coke generated from coking coal with different metamorphic degrees.
Muruntau open pit mine has been in operation since 1967 and is one of the largest open pit mines in the world. As per the project of mining phase V effective since 2020, it is among the world’s three largest open pit mines. The distribution of ore reserves per horizons is analyzed with regard to nature-and-process zones delineated in Muruntau–Myutenbai joint open pit mine. The project parameters of the pit and the scope of mining operations were determined from the geological and mathematical modeling including the detailed survey data and borehole assay results. The open pit mining scenarios within the project limits of mining phase V up to 2030 are considered. The open pit mining scheduling is performed with regard to operational specifics of the deposit, number of nature-and-process zones and duration of the scheduling period. It is concluded that maintenance of the required gold content of ore to be processed needs stimulation of the annual mining output up to 50–60 Mm3 in the easterly direction of the pit at the preserved production output in all nature-and-process zones. To this effect, it is required to formulate a sustainable action plan, with the assigned performance indicators, with regard to the Extra Activity Progr am to Improve Production of Precious Metals at Navoi Mining and Metallurgical Combinat over the period to 2026 and further on to 2040. The authors appreciate participation of Head of a Department at VNIPIpromtekhnologii, Candidate of Engineering Sciences A. V. Seleznev in this study.