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Objective: The study aimed to investigate the effects of Periplaneta americana glycoprotein (PAG) on the growth and metabolites of Lactobacillus plantarum and Bifidobacterium adolescentis. Methods: With inulin as a positive control, the probiotic bacteria were cultured in medium containing different concentrations of PAG (MRS medium with PAG concentrations of 0.5, 1.0, 2.0, and 4.0 mg/mL, respectively. TPY medium with PAG concentrations of 1.0, 2.0, 4.0, and 8.0 mg/mL, respectively) to determine the OD600 and pH, and the contents of lactic acid, short-chain fatty acid (SCFA, snamely acetic acid, propionic acid and butyric acid) in the bacterial solution. Results: The growth of Lactobacillus plantarum was greatest when the concentration of PAG reached 1.0 mg/mL, while Bifidobacterium adolescentis grew best with a PAG concentration of 2.0 mg/mL. The OD600 value, production of lactic acid and SCFAs of Lactobacillus plantarum solution at 1.0 mg/mL PAG were higher than those of inulin, while the pH value was significantly lower. In the bacterial solution of Bifidobacterium adolescentis with 2.0 mg/mL PAG, the values of OD600 and the production of propionic acid and butyric acid increased compared to the same concentration of inulin, the lactic acid production was better than that of inulin at 12 h, the acetic acid production was better than that of inulin at 24 h, and the pH value decreased, indicating that PAG and inulin had different effects on promoting Bifidobacterium adolescentis to produce lactic acid and SCFAs. Conclusion: The PAG could promote the proliferation and organic acid production of Lactobacillus plantarum and Bifidobacterium adolescentis, and the effect was better than that of inulin.

Accurately determining the casing breakage characteristics in mining wells and proposing corresponding preventive and control measures can provide an important guarantee for the long-term stability of the wellbore. Taking the No. 21 coal seam and overlying strata in the Pingdingshan mining area as the research object, theoretical calculations and numerical simulation were used to determine the stress and displacement distribution law of separation section in the overlying strata. The correlation between the height of the overlying strata, the horizontal distance from the working face and stress and displacement were analyzed, and the relationship between the height of the overlying strata, the horizontal distance from the working face and the stress and displacement were fitted. Based on the actual development experience of mining wells in the research area, the main types of casing breakage in the optimal well layout area were determined. Combined with the commonly used casing mechanical parameters, the casing breakage location and length under the “two field” evolution were characterized. The commonly used local protection technologies for mining wells was summarized and the corresponding preventive and control measures were proposed. The results shown that, in the process of working face advancement, the stress of the overlying strata shown a change pattern of from fluctuation to linear decrease, and the displacement shown a change pattern of from almost unchanged to hyperbolic type. The casing in the optimal well layout area was mainly characterized by tensile shrinkage and shear fracture, and the casing reinforcement was applied to reinforce the casing in mining well. When N80 casing was used in the third section of the ground mining well in the research area, it was necessary to install anti- tensile and shear casing reinforcement in the upper 46 m of the coal seam at the sub-critical layer and in the upper 54 m of the coal seam at the soft/hard interlayer. When P110 casing was used, it is necessary to install anti-tensile reinforcement in the upper 46 m of the coal seam at the sub-critical layer. It is recommended to use P110 casing for all three sections of the surface mining wells in the research area to increase the wellbore stability in mining well. The research achievement can provide theoretical guidance for preventing casing breakage in the Pingdingshan mine and mining wells under similar conditions.

Aiming at the problem of low degree of exploration and research of geothermal geological conditions in the Shifugou area, which seriously restricts the development and utilization of geothermal resources, on the basis of available data, the geothermal geological conditions and the characteristics of the thermal reservoir in the Lanzhou faulted basin are summarized. Combined with the exploration results of the controlled source audio frequency magnetotelluric (CSAMT) method, the potential of geothermal resources development in the Shifogou area in the southern part of the basin is inferred. The results show that (1) the geothermal geological conditions in the Lanzhou faulted basin are obviously different. Taking the buried faults of Shengouqiao (F5) and Leitai River (F8) as the boundary, respectively, the faulted basin can be divided into the western Xigu district, central Qilihe district and eastern Chengguan-Shifogou district. (2) The geothermal temperature increases from west to east, and increases vertically from the depth of 2000 to 2500 m, inferring that this is the basic depth of geothermal exploitation in the Lanzhou faulted basin. (3) In the southern section of the eastern part may exist layered-conductive geothermal resources and fault-zone geothermal resources, it is inferred that there may exist “combined type” of layered and banded geothermal water in the Shifogou district, which is located in the F2 fracture zone or the intersection of F2 fracture zone and F8 fault zone. It is suggested that the exploration and production well depth of geothermal water in the faulted-zone thermal reservoir should be considered as 800−1100 m, and that the exploration and production well depth of the “combined” layered thermal reservoir should be considered as 1500−2000 m. The wellhead geothermal water temperature in this area is expected to reach 50−60 °C, the single well yield can reach 500−1000 m3/d, and the quality of the geothermal water can reach the standard for medical bathing. The results can provide a basis for geothermal resources exploration in Lanzhou.

6061-T6 aluminum alloy plate (3 × 150 × 300 mm3) was welded by tungsten inert gas (TIG) welding. The welding process methods are single-pass welding process and full welding process respectively. The effects of different welding processes on the performance of TIG welding 6061-T6 aluminum alloy were compared and studied. The effects of microstructure and precipitation on the microhardness and tensile strength were analyzed by optical microscope, scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) characterization, electron backscattering diffraction (EBSD) characterization, microhardness and tensile test. The microstructure of the weld zone is mainly composed of aluminum solid solution (α-Al) dendritic structure and Al–Si eutectic structure. Through EBSD characterization analysis, the average grain size of the weld zone of the full welding process and the single-pass welding process is about 45 μm and 55 μm, and the grain size of the heat-affected zone and the weld zone of the two welded joints does not change significantly. The hardness curves of the two welded joints have the same distribution trend, which is roughly 'W' type distribution. In the tensile test, the tensile strength of the single pass welding process is lower than that of the full welding process, and the fracture of the tensile parts is dimple structure, which is ductile fracture. Through analysis and comparative study, the full welding process is better than the single-pass welding process when welding 6061-T6 aluminum alloy sheet.

Biodegradation is one of the important ways for the clean and efficient utilization of coal. However, the effectiveness of degradation by the combination of fungi and bacteria has not been well understood. In the present study, the combined degradation of the Yima coal was tested. The coal samples were firstly oxidized with nitric acid, followed by cultured in the media of Cunninghamella elegans and Bacillus sp.. The absorbance of A450, pH and metallic element (Cr, As, Mn, Pb, Co, Ni, Cu, Zn, Mo) contents of the degradation solution were determined by UV-visible spectrophotometry, pH meter and inductively coupled plasma mass spectrometry, respectively. The humic acid was analyzed by element analyzer, Fourier transform infrared spectroscopy and gas chromatog-raphy-mass spectrometry. The results showed that the humic acid yields of C. elegans, Bacillus sp. and their mixture were 58.17%, 61.00% and 67.17%, respectively. The pH of the degradation solution of mixed strains was similar to that of the bacteria. The characteristic products of the bacteria degradation were detected in the humic acid samples derived from mixed strains, while the opposite was true for the fungi. It was suggested that the combination of the two strains enhanced the alkaline environment and improved the degradation rate of nitric acid-treated coal. The bacteria played a leading role in the degradation process. Metallic elements (Cr, As, Mn, Pb, Co, Ni, Cu, Zn, Mo) were transferred from coal to the degradation solution during the degradation process, and the contents of Cr, As, Pb, Ni, Cu and Mo were fitted with A450, the coefficient of determination (R2) were greater than 0.6. It indicated that the contents of these six metal elements in the degradation solution could represent the degradation rate. Chemically extracted humic acid and biologically extracted humic acid were rich in the active functional groups such as carboxyl, hydroxyl, carbonyl, long-chain fatty acids (C16, C18) and four pyrrole derivatives. The biologically extracted humic acid also contained fatty acids (C3, C4, C5, C13, C14, C15), of smaller molecular weight, as well as nitrogen-containing compounds such as two pyrrole derivatives and a furan. The contents of C and H elements in the biologically extracted humic acid were higher than that in the chemically extracted humic acid.

The occurrence and production of coalbed methane is related to the development degree of pore system in coal reservoirs. The pore structure characteristics of original structural coal seam will change significantly after damage and deformation, thus affecting the adsorption/desorption and diffusion process of coalbed methane. Through the low-temperature liquid N2 and low-pressure CO2 adsorption analysis and isothermal adsorption experiments on coal with different structures from the No. 3 coal seam in Zhaozhuang coalfield in Qinshui Basin, the variation laws of pore structure and adsorption of coals with various destructive strengths were analyzed. Applying experimental data and numerical fractal modeling, the pore fractal characteristics of coal with different structures and their effects on methane adsorption and diffusion in coal were revealed. The results shown that with the increase of the destructive intensity of coal structures, the specific surface area and pore volume of coal increased, the proportion of 50-300 nm pores gradually decreased, the micropores and mesopores of 2-50 nm and ultra-micropores of less than 2 nm increased. As the main adsorption pores in coal, the ultra-micropores size was mainly distributed in 0.45-0.65 nm and 0.80-1.0 nm. The adsorption amount of N2, CO2 and CH4 increased with the increasing destructive degree of coal structure. The order of adsorption capacity from large to small was: intact coal>mylonitic coal > granulated coal > cataclastic coal. The fractal dimensions of the micro-, meso- and macro-porous structures indicated that the pore structure of tectonically deformed coals will be simplified. Coal with a higher damage intensity had a rougher pore surface (corresponding to a higher D1) and a more homogeneous pore size distribution (corresponding to a lower D2). The fractal dimension of ultra-microporous (Dm) gradually increased with the increasing structural destruction intensity of coal, and was positively correlated with Langmuir constant (VL) and the corresponding specific surface area, indicating that the increase of coal surface roughness led to the increase of specific surface area, which provided more adsorption points with high adsorption potential for gas adsorption and enhanced the adsorption capacity of coal. The effective diffusion coefficient and pore volume were positively correlated with the fractal dimensions D1 and negatively correlated with D2, which indicated better pore connectivity, increased pore volume, improved gas inlet and outlet efficiency, and enhanced gas diffusion efficiency of destroyed intact coal.

At cold temperatures, the stress after welding a blast furnace shell is not completely released because of the fast cooling speed, which results in cracks. To solve this problem, an integrated method combining gray relational analysis, back propagation (BP) neural network, and genetic algorithm-BP (GA-BP) was proposed in this study. Its aim was to analyze the dominant mechanism of residual stress in multi-layer and multi-pass welding process under the heating of ceramic sheet and achieve super-objective collaborative optimization of residual stress. GRA indicated that through the correlation analysis of welding parameters, residual stress, maximum temperature of characteristic point, and deformation, welding speed was determined to be an all-important factor affecting welding quality. A BP prediction model of residual stress was established. The predicted value was in good agreement with the experimental value, and the maximum error was 8.75%. The influence of each factor on the quality of welding seam is not a single, but a complex mechanism of mutual influence. GA-BP determined the combination of low level welding speed 28 mm/min, medium level welding current 210A and medium and low level welding voltage 21V as the optimal solution of low residual stress. The maximum prediction error of residual stress was 13.76%. The experimental results show that the maximum prediction error of residual stress is 4.4%, and the optimized weld has better macro and micro structure, which proves the feasibility of the multi-objective optimization method. Most importantly, the proposed method can effectively identify the optimal welding parameters, which can provide a reliable theoretical basis for engineering practice.

Explosion-welded steel/Al composite plate has advantages of excellent conductivity, heat conductivity, light weight, and corrosion resistance. While the elongation of explosion-welded steel/Al composite plate can not been predicted by the traditional damage fracture theory. Establishing a new prediction model to analyze the deformation behavior of steel/Al composite plate are necessary. First, the deformation behavior and interface microscopic characteristics of explosion-welded steel/Al composite plate were analyzed using uniaxial tensile tests and SEM experiments, the result showed that wave structure, brittle phase, and microcrack existed at the interface layer of composite plate, the uniform elongation and elongation of steel/Al composite plates basically deviate linearly from the mixing law. Second, simulation models were established to analyze the effect of interface wave structure, brittle phase, and interface microcracks on the instability and fracture behavior of explosion-welded steel/Al composite plate. The interface wave structure could enhance the elongation of the composite plate, while the uniform elongation of the composite plate decreased with the increasing of brittle phase and microcrack. When f0 = 0.985, the predicted tensile strength through simulation is 258.94 MPa, which only has a difference of 1.9 MPa from the experimental value, when the length of the crack increases from 0.03 mm to 0.2 mm, the uniform elongation of the composite plate decreases by 92.52%. Finally, M−K theory considering the characteristics of interface defects was established to predict the tensile instability behavior of steel/Al composite plates. The instability behavior of the composite plate considering interface defects could be accurately described using the modified M−K theory when the height of the interface groove of the composite plate was Δta/Δts=ha/hs and Δta+Δts=0.5mm.

In this paper, a novel method was proposed to improve the production efficiency and formability of titanium alloy, which was named triple-layer sheet hot stamping with a cold die cooling (THF). The titanium alloy sheet was clamped by two steel sheets with no adhesive added, then heated, transferred and formed together. In order to verify the ability in enhancing formability of this process, spherical part forming tests were carried out to study the formability under the single-layer sheet hot stamping (SHF) and THF. Finally, a plug socket part was formed to verify the practicability of the novel forming process. The finite element (FE) model was established to analyze the forming process finding that the formability of the parts were significantly improved after using THF process. Comparing with SHF process, the stamping depth increases by 135.7% at 900 °C in the THF process. The forming limit strain increases from 0.18 of the single-layer sheet to 0.51 of the triple-layer sheet. The forming limit strain obtained by the THF process is close to that of isothermal forming. The friction state is one of the main reason for improving formability. Moreover, for plug socket parts, there is almost no thinning of the part in the THF process at 900 °C. In conclusion, it has great advantages in improving the formability of titanium alloy using the THF process.

An accurate material constitutive model is very important to apply numerical simulation technology to predict, establish and optimize the thermoplastic forming process parameters of powder titanium alloy. To achieve this goal, the microstructure evolution and densification of TC4 powder titanium alloy were investigated during compression at temperatures from 860 °C to 960 °C, strain rates from 0.05 s−1 to 20 s−1 and strains from 0.357 to 1.204. The results show that the microstructure undergoes dynamic recrystallization under different conditions. High temperature, large deformation degree and low strain rate are helpful to reduce porosity, pore size and pore colony. Plastic deformation and diffusion are two main mechanisms of densification. The microstructure evolution and densification model were established, combining the power constitutive law, a unified constitutive model was proposed to predict flow stress, microstructure and relative density of TC4 powder titanium alloy. The model constants were determined through a genetic algorithm. The predicted values of flow stress and relative density agreed well with the experimental values. The variations in relative density with temperature, strain rate and strain were analyzed based on the prediction results.

Background: The arrival of the big-data era provides us with a chance to elaborate the spectrum and epidemiological characteristics of infectious diseases in children and adolescents aged 0–18 years in the pre-COVID-19 pandemic era. Methods: We collected data on infectious diseases in 891,981 participants from the Cheeloo Lifespan Electronic Health Research Data-library. The incidence density of each infection was calculated and stratified by age and region. The annual percentage change (APC) in incidence was estimated by logarithmic linear regression. Results: A total of 18,183 cases of 78 infections were diagnosed, with an overall incidence density of 626.33 per 100,000 person-years (PY). Of these, 6825 cases of 50 non-notifiable infectious diseases were identified. Children aged 1–3 years had the highest incidence of infections. The overall incidence revealed a significant increasing trend from 2013 to 2017 (APC = 36.9%, p < 0.05). Hand, foot, and mouth disease, pneumonia, and influenza were the three most common diseases. The incidence of pneumonia, rubella, scarlet fever, zoster, molluscum contagiosum, and syphilis increased significantly during the study period (all p < 0.05). Taian, Binzhou, and Weihai had the highest incidence of all other cities. The incidence of gastrointestinal infections increased markedly in the eastern coastal regions. Conclusions: More stress should be placed on a number of non-notifiable infectious diseases with a high burden and a significant increasing trend. Age-based and regional targeting efforts are needed to prevent and contain infectious diseases among children and adolescents.

Controlling the grain size is an essential issue in the metal plastic working processes. Based on the consensus view that grain boundaries are impassable borders for dislocations and that the number of dislocations within a grain affects the stress builds up among the adjacent grains, altering grain size has a great influence on the post-forming mechanical properties of the deformed workpieces. In the present research, the deformation behaviors of 20CrMoH, a typical hardenability steel, are investigated and the microstructure evolution of grain growth experiencing heat load and grain refinement under deformation load is also uncovered. According to the experimental stress-strain curves and grain size variation data, a set of internal variable constitutive equations are established, in which the material constants are calibrated by a genetic optimization algorithm. Comparing the predicted curves with the experimental values, it can be concluded that the constitutive equations can accurately reproduce the thermal deformation behaviors and grain size variation of the steel. The correlation coefficient of the calculated and experimental values is 0.9861, and the average relative error approximates 4%. The unified constitutive equations are compiled into a commercial finite element software with the help of user-defined subroutine interfaces. The simulation results demonstrate that the maximum accuracy error of a hollow shaft size is about 10%, and the error in the average grain size is 12.1%. It is confirmed that the internal variable constitutive equations describing the evolution of grain size established in this paper are suitable for the numerical simulation of the bulk-forming process.

Climbing manufacturing robots can create a revolutionary manufacturing paradigm for large and complex components, while the motion control of climbing manipulation-oriented robots (CMo-Rs) is still challenging considering anti-slippage problems. In this study, a CMo-R with full-scenery climbing capability and redundant load-bearing mobility is designed based on magnetic adsorption. A four-wheel kinematic model considering the slipping phenomenon is established. An adaptive kinematic control algorithm based on slip estimation using Lyapunov theory is designed for uncertain inclined planes. For comparison, the traditional PID-based algorithm without slip consideration is implemented as well. Numeric simulations are conducted to tackle the trajectory tracking problems for both circular and linear trajectories on the horizontal plane (HP), 50° inclined plane (50° IP), 60° inclined plane (60° IP), and vertical plane (VP). The results prove that our approach achieves better tracking accuracy. It demonstrated applicability in various climbing scenarios with uncertain inclined planes. The results of experiments also validate the feasibility, applicability, and stability of the proposed approach.

Abstract The fabrication of high‐speed electronic and communication devices has rapidly grown the demand for high mobility semiconductors. However, their high cost and complex fabrication process make them less attractive for the consumer market and industrial applications. Indium nitride (InN) can be a potential candidate to fulfill industrial requirements due to simple and low‐cost fabrication process as well as unique electronic properties such as narrow direct bandgap and high electron mobility. In this work, 3 µm thick InN epilayer is grown on (0001) gallium nitride (GaN)/Sapphire template under In‐rich conditions with different In/N flux ratios by molecular beam epitaxy. The sharp InN/GaN interface monolayers with the In‐polar growth are observed, which assure the precise control of the growth parameters. The directly probed electron mobility of 3610 cm2 V‐1 s‐1 is measured with an unintentionally doped electron density of 2.24 × 1017 cm‐3. The screw dislocation and edge dislocation densities are calculated to be 2.56 × 108 and 0.92 × 1010 cm‐2, respectively. The step‐flow growth with the average surface roughness of 0.23 nm for 1 × 1 µm2 is confirmed. The high quality and high mobility InN film make it a potential candidate for high‐speed electronic/optoelectronic devices.

Conjunction gears, which are also known as helical gears with clutch gears, are used mainly in the transmission and shift design of automobile gearboxes. In this paper, focusing on the hot forging process and microstructure changes after forging, hot forging is proposed for manufacturing a conjunction gear according to the characteristics of a combination gear. Combined with finite element numerical simulation, by comparing changes in temperature, equivalent stress, equivalent strain, recrystallization fraction, and average grain size, the effect of the optimization of the forging process of a combined tooth billet is achieved using the response surface methodology. Finally, optimal forging process parameters are obtained through experimental research, and the quenched structure after hot forging is observed.

Based on the Gurson-Tvergaard-Needleman (GTN) damage model, the damage evolution and ductile fracture of 7075 aluminum alloy sheets during the tensile process were predicted. First, the true stress–strain curve and micro morphology of 7075 aluminum alloy at 310 °C∼460 °C were obtained using ultra-high temperature confocal microscope with tensile and compression functions, and the damage characteristics of the fracture position of the tensile specimen were observed by Scanning Electron Microscope (SEM). Then, using the finite element reverse calibration method, the identification method of GTN damage parameters under high temperature was systematically explained and the damage characteristic parameters of 7075 aluminum alloy under high temperature (310 °C∼460 °C) were obtained. The influence of fluctuations in damage parameters on the macroscopic mechanical behavior of materials and the influence of temperature on the value of material damage variables were analyzed. Finally, the void volume fraction of 7075 aluminum alloy at 360 °C was obtained by microscopic observation and compared with the void volume fraction obtained by the finite element reverse calibration method. The results show that the effect of temperature on void volume fraction is basically the same as that of plasticity. The change of void volume fraction has a greater impact on the mechanical properties of the material. There is a small gap between the void volume fraction obtained using the microscopic observation method and the void volume fraction obtained using the finite element reverse calibration method, which verifies the accuracy of the finite element reverse calibration method.

At present, the macro-parameters such as critical desorption pressure, comprehensive diffusion coefficient, and permeability are commonly used to characterize the properties of a reservoir, and the productivity of coalbed methane (CBM) wells can be predicted through numerical simulation or established mathematical models, and the types of low-producing CBM reservoirs can be classified. However, low production from CBM wells is often caused by the weakness of one (or more) of desorption, diffusion, and seepage in CBM reservoirs, and the evaluation of a single link and macro-parametric characterization of reservoir properties cannot really ascertain the cause of the low production from a given CBM well.In the present work, the influences of pores and fracture structure, fluid flow dynamics and resistance on the desorption, diffusion, and seepage of CBM were considered from the perspective of system theory, and the evaluative parameter index system of low-productivity reservoirs was established. This avoids the one-sidedness of the evaluative results arising when only considering macro-parameters. New methods of obtaining the evaluative parameters pertaining to desorption, diffusion, and seepage are proposed: the methods include isothermal adsorption experiments, the use of logging curves, drainage data, mercury injection, and a classical mathematical model. These methods combined the data from experiments with in-situ data, and ensure the accuracy and practicability of the resulting evaluative parameters. On this basis, types of low-production reservoirs were classified using an analytic hierarchy process with multi-parameter superposition.The evaluative results pertaining to Shizhuang North block in the Qinshui Basin, Shanxi Province, China show that there are six types of low-yield reservoirs among the evaluative wells tested. Among them, diffusion is the main factor governing the low yield of CBM wells, followed by desorption and seepage. Herein, the reservoir constraint on CBM production is comprehensively evaluated, identifying the main controlling link affecting the low productivity of CBM wells, and laying a theoretical foundation for targeted transformation measures.

Most of the previous studies exploring the changing patterns of wetland in the Yellow River Delta (YRD) were conducted based on sparse time-series images, which ignored its severe environmental gradient and rapid evolution process of the wetland. The changes in the dominant factors in the evolution of the wetland in the YRD are not clear. This study used the dense time-series Sentinel-2 images to establish a wetland database of the YRD, and then analyzed the spatial distribution characteristics of, and temporal changes in, the wetland during 2015–2022. Finally, the dominant factors of the spatio-temporal evolutions of the wetland were explored and revealed. The results showed the following. (1) During 2015–2022, the wetland in the YRD was dominated by artificial wetland, accounting for 54.02% of the total wetland area in the study area. In 2015–2022, the total wetland area increased by 309.90 km2, including an increase of 222.63 km2 in natural wetlands and 87.27 km2 in artificial wetlands. In the conversion between wetland types, 218.73 km2 of artificial wetlands were converted into natural wetlands, and 75.18 km2 of natural wetlands were converted into artificial wetlands. The patch density of rivers, swamps, and salt pans increased, showing a trend of fragmentation. However, the overall degree of landscape fragmentation in wetlands weakened. The trend of changes in the number of patches and landscape shape index was the same, while the trend of changes in Shannon’s diversity index and Contagion index was completely opposite. (2) Natural factors, such as precipitation (0.51, 2015; 0.65, 2016), DEM (0.57, 2017; 0.47, 2018; 0.49, 2020; 0.46, 2021), vegetation coverage (0.59, 2019), and temperature (0.48, 2022), were the dominant influencing factors of wetland changes in the YRD. The dominant single factor causing the changes in artificial wetlands was vegetation coverage, while socio-economic factors had lower explanatory power, with the average q value of 0.18. (3) During 2015–2022, the interactions between the natural and artificial factors of the wetland changes were mostly nonlinear and showed double-factor enhancement. The interactions between temperature and sunshine hours had the largest explanatory power for natural wetland change, while interactions between precipitation and vegetation coverage, and between temperature and vegetation coverage, had large contribution rates for artificial wetland change. The interactions among natural factors had the greatest impacts on wetland change, followed by interactions between natural factors and socio-economic factors, while interactions among socio-economic factors had more slight impacts on wetland change. The results can provide a scientific basis for regional wetland protection and management.

For the purpose of manufacturing the automotive body structure parts with tailored properties, the hot stamping process with partial heating was experimentally and numerically investigated. In this study, the deformation behaviors of the steel 22MnB5 with the fully and incompletely austenitized microstructure were studied by hot tensile testing and modeled by the modified Zerilli–Armstrong constitutive equations taking the lattice structure into account. The classical Kirkaldy–Venugopalan transformation kinetics equations were modified to be suitable for the investigated steel, and the diffusional phase transformation equations were calibrated by using the continuous cooling transformation data. By the virtue of user subroutine VUHARD in finite element program ABAQUS, the metallurgical-field coupled finite element model was established for simulating the hot stamping process with partial heating. A special fixture was developed to realize the partial heating process of circular sheet blank. The finite element simulation and experimental research were carried out for a cup-shaped part. Finally, the phase distribution, hardness variation, shape error, and thickness variation of the cup-shaped part were analyzed and discussed. The validity and accuracy of the constitutive model and the transformation kinetics model were verified by comparing the simulation results with the experimental data. Besides, the present research results also demonstrate the hot stamping parts with variable mechanical properties can be manufactured by changing the austenitization degree of sheet blank during the heating stage.

The wear resistance and hardness of stainless steel (SS) balls formed by cold skew rolling are effectively improved due to the change in internal microstructure. In this study, based on the deformation mechanism of 316L stainless steel, a physical mechanism-based constitutive model was established and implemented in a subroutine of Simufact to investigate the microstructure evolution of 316L SS balls during the cold skew rolling process. The evolution of equivalent strain, stress, dislocation density, grain size, and martensite content was studied via simulation during the steel balls’ cold skew rolling process. The corresponding skew rolling experiments of steel balls were carried out to verify the accuracy of the finite element (FE) model results. The results showed that the macro dimensional deviation of steel balls fluctuates less, and the microstructure evolution agrees well with the simulation results, which proves that the established FE model has high credibility. It shows that the FE model, coupled with multiple deformation mechanisms, provides a good prediction of the macro dimensions and internal microstructure evolution of small-diameter steel balls during cold skew rolling.

The high-temperature deformation process and dynamic recrystallization (DRX) process of 21-4N were investigated under the conditions of the deformation temperature range of 1273~1453K, the strain rate range of 0.01~10s–1 and the deformation degree of 60% (the total deformation is 0.916) by using Gleeble-1500D thermal simulated test machine. The curves of stress-strain (σ – ε) were obtained, and the curves of work hardening rate (θ) and strain (ε) were obtained by taking derivative of σ – ε. The DRX critical strains under different conditions were determined by the curves of work hardening rate (θ – ε), and the DRX critical strain model was established. The peak strains of 21-4N were obtained by the curves of σ – ε, the relationship between peak stress (σp) and critical strain (εc) was determined, and the peak strain model was established. The DRX volume fraction models of 21-4N were established by using Avrami equation. The DRX grain size of 21-4N was calculated by Image Pro Plus 6.0, and its DRX grain size models were established.

The Gleeble-1500D thermal simulator was used for the isothermal compression test of 21-4N heat-resistant steel under the T range of 1273–1453 K and ε˙ of 0.01–10s−1. Using the obtained stress - strain data, various parameters of the Fields–Backofen (F-B), the modified F–B (m–F–B) equations and the modified Zerilli–Armstrong (m–Z–A) equations were calculated respectively. The constitutive equations of 21-4N heat-resistant steel based on the F–B, the m–F–B and the m–Z–A were established. Second, the predictive ability of the three constitutive equations were evaluated using the correlation coefficient (R), average absolute relative error (AARE) and the relative error (r). Third, the established model was imported into Deform-3D to simulate the valve forging process of 21-4N heat-resistant steel, and the distribution rules of the effective stress, effective strain, temperature and damage condition of the forging were analyzed. Finally, a hot forging experiment was performed on a 160t hot die forging press. Results show that the flow stress of 21-4N heat resistant steel is affected by temperature, strain rate and strain. The m–F–B and m–Z–A models can describe the rheological behavior of 21-4N heat-resistant steel, while the original F–B model has a high predictive ability, but only under low temperature, low strain rate and small deformation. The simulation process can be completed successfully, indicating that the established models can be used for the simulation study of the thermal deformation of 21-4N heat-resistant steel and all models are correct. The results can provide some important basic data for the simulation of 21-4N heat resistant steel in the plastic deformation process.

Background: Air pollution leads to many adverse diseases, especially respiratory diseases and cardiac symptoms. However, it has not been studied the association between air pollution and influenza cases in Jinan City, especially during the outbreak of COVID-19; Methods: The data were obtained from China’s Disease Information System, and influenza cases during 2020–2021 in Jinan City were collected from it. We used the generalized additive Poisson model to measure the association between air pollutants and the daily influenza cases after adjusting for possible influence variables; Results: There were 4767 influenza cases. PM2.5 and PM10 on lag 0, lag 3, and lag 4 were significantly associated with an increased risk of influenza; gaseous pollutants (NO2 and SO2) led to higher risk than particulate matter pollutants (PM2.5 and PM10). There were no significant differences for sex subgroup analyses. Except for O3, the incidence risk of males and females was highest on lag 3 and lag 4. For the study of different age groups, influenza cases aged over 59 years had a slightly larger relative risk when exposed to all air pollutants (except O3) than the younger group; Conclusions: The overall number of influenza cases decreased in 2020–2021. PM2.5, SO2, CO, and NO2 were significantly associated with the risk of influenza during 2020–2021. Countermeasures should be developed according to the characteristics of influenza risk to prevent and control it.

To investigate the biogas generation characteristics of the organic matter in lignite, methanol extraction was conducted to obtain the soluble fraction and the residual of lignite, which were subsequently taken as the sole carbon source for biogas production by a methanogenic consortium. Afterward, the composition of compounds before and after the fermentation was characterized by UV-Vis, GC-MS, and HPLC-MS analysis. The results indicated that the methanogenic microorganisms could produce H2 and CO2 without accumulating CH4 by utilizing the extract, and the methane production of the residue was 18% larger than that of raw lignite, reaching 1.03 mmol/g. Moreover, the organic compounds in the methanol extract were degraded and their molecular weight was reduced. Compounds such as 1, 6-dimethyl-4-(2-methylethyl) naphthalene, 7-butyl-1-hexylnaphthalene, simonellite, and retene were completely degraded by microorganisms. In addition, both aromatic and non-aromatic metabolites produced in the biodegradation were detected, some of which may have a negative effect on the methanogenesis process. These results revealed the complexity of the interaction between coal and organism from another point of view.

Over the past several decades, the increasing popularization of psychological counseling has underlined a strong need for an indigenous approach to counseling. The current study adopted a single-case study method to construct a narrative of the indigenization process of psychotherapy in mainland China based on a comprehensive description of one prominent counseling psychologist’s experience over the past half-century. Through interviews and records of fieldwork involving the psychologist (as the case) in 10 months between 2016 and 2017, the current study analyzed the indigenization process from the following three aspects: knowledge production, counseling practice, and student training. The findings showed that there was an underlying tension between the psychologist’s traditional wisdom and his professional training in scientific psychology during the indigenization process. However, the findings of this study further revealed something missing from previous studies. First, the client-centered counselor did not assume “power” during counseling sessions, which differs from critical viewpoints in medical anthropology. Second, the students being trained underwent fundamental changes in values rather than learning a technique or resolving problems. Third, the psychologist’s life history affected his thoughts and professional practice, which occurred in a sociocultural historical context. Finally, the implications for the future direction of the indigenization of counseling practice are discussed.

A metal-melting direct writing process, using semi-solid isothermal heat treatment to form high-quality semi-solid components, realized the integrated innovation of semi-solid formation and additive manufacturing. An experimental study was carried out on semi-solid isothermal heat treatment for metal-melting direct-writing technology, using 2A12 aluminum alloy as raw material. The semi-solid isothermal heat treatment was carried out over different temperature ranges, and four-stages evolution mechanism of the semi-solid microstructure in the semi-solid melting direct writing process was investigated. The effects of holding temperature and time on the microstructure of the semi-solid isothermal heat treatment of the alloy were put forward. According to the analysis of the results of the semi-solid-melting direct-writing test, the corresponding relationship between semi-solid microstructure and extrusion formability was found. The results show that when the holding temperature is 640–650 °C and the holding time is 20–25 min, the liquid phase rate can reach about 40%, and the direct-writing forming technology can be carried out stably.

Solution and aging heat treatment are effective means to improve the mechanical properties of Al-Li alloys. The solution treatment and aging treatment tests of 2060 Al-Li alloy were carried out. The yield strength, tensile strength, elongation, Vickers hardness, and microstructure of specimens after heat treatment were obtained by the tensile test at room temperature, Vickers hardness test, SEM analysis, TEM analysis, and EDS analysis. The effects of solution and aging heat treatment parameters on mechanical properties of 2060 Al-Li alloy were analyzed by response surface model and test results. The results show that sufficient solution can make the Cu-rich second phase of the alloy continuously dissolves into the aluminum matrix, and consequently obtain the supersaturated solid solution, the insoluble second phase is mainly θ’ (Al2Cu) phase, T(Al2Cu2Mg3) phase, and S’ (Al2CuMg) phase. The strength and hardness of the alloy are improved, but the ductility worsens with the degree of solution treatment enhances. With the increase of aging temperature and aging time, the strength and hardness of the alloy increase, but the elongation decreases. Taking tensile strength, elongation, and Vickers hardness of the alloy as the optimization objectives, the NSGA-II multi-objective optimization algorithm was used to optimize the process parameters of solution and aging heat treatment, and the heat treatment experiment was carried out. The optimization results show that the best mechanical properties of the alloy with matching strength and toughness can be obtained under the solution treatment at 466 °C/60 min and aging treatment at 185 °C/13 h.

In order to improve the classification accuracy of patients with autism based on the full Autism Brain Imaging Data Exchange dataset, a total of 501 subjects with autism and 553 subjects with typical control across 17 sites were involved in the study. Firstly, we applied the resting-state functional magnetic resonance imaging data to calculate the functional connectivity (FC) based on the automated anatomical labeling atlas with 116 brain regions. Secondly, we adopted the support vector machine-recursive feature elimination algorithm to select top 1000 features from the primitive FC features. Thirdly, we trained a stacked sparse auto-encoder with two hidden layers to extract the high-level latent and complicated features from the 1000 features. Finally, the optimal features obtained were fed into the softmax classifier. Experimental results demonstrate that the proposed classification algorithm is able to identify the autism with a state-of-the-art accuracy of 93.59% (sensitivity 92.52%, specificity 94.56%).

Cross wedge rolling has the advantages of high production efficiency, good product quality, high material utilization, environmental protection, and low cost. It is one of the best processing methods for producing shaft blanks. In this paper, a cross wedge rolling die of TC4 titanium alloy is studied. Based on the Archard wear model, a modified model suitable for cross wedge rolling die wear analysis is derived through finite element simulation. Then, the modified Archard wear model is imported into Deform-3D software for finite element analysis. Orthogonal experimental design is used to combine and analyze different process parameters. Finally, the beetle antennae search (BAS)-genetic algorithm (GA)-back propagation neural network (BPNN) algorithm is used to predict the degree of die wear and to optimize the simulation parameters, which can acquire the process parameters that have the least impact on die wear. The results show that the wear distributions of cross wedge rolling tools is uneven. In general, the most serious areas are basically concentrated in the wedge-shaped inclined plane and rectangular edge lines. The reason is that the tangential force and radial force received by the die are relatively large, which leads to increased wear. Moreover, the temperature change is most severe on the wedge-shaped ridge line. When in contact with the workpiece, the temperature rises sharply, which makes the local temperature rise, the mold hardness decrease, and the wear accelerate. Through response surface method (RSM) analysis, it is concluded that the deformation temperature is the main factor affecting wear depth, followed by the forming angle, and that there is an interaction between the two factors. Finally, the feasibility of the BAS-GA-BP algorithm for optimizing the wear behavior of dies is verified, which provides a new process parameter optimization method for the problem of die wear in the cross wedge rolling process.

In order to more accurately predict the plastic flow behavior of 33Cr23Ni8Mn3N heat-resistant steel, it provides a good foundation for numerical simulation. The selection of constitutive models is crucial. The Gleeble-1500D thermal simulation tester was used to perform thermal compression experiments on 33Cr23Ni8Mn3N heat-resistant steel under different deformation conditions. Based on the experimental data, the Johnson-Cook (JC), Fields-Backofen (FB) constitutive models and their modified constitutive models are established and compared. The characteristics of JC model, FB model, modified JC (m-JC) model, modified FB (m-FB) model and strain-compensated Arrhenius (strain-compensated Arr) model are demonstrated. It is determined that the strain-compensated Arr model has the best accuracy for predicting the thermal deformation behavior of 33Cr23Ni8Mn3N heat-resistant steel. In addition, finite element development was carried out and programming was performed using Absoft Pro Fortran 8.0 software. Various modified models are embedded in Deform-3D for numerical simulation comparison. The results of numerical simulation show that the strain-compensated Arr model is more suitable for finite element simulation of 33Cr23Ni8Mn3N heat-resistant steel. Keywords: 33Cr23Ni8Mn3N, Johnson-Cookmodel, Thermal deformation, Constitutive equation, Fields-Backofen model

Bioconverting coal to methane is a green and environmental friendly method to reuse waste coal. In this study, heterologous bacteria were used for the gas-producing fermentation of lignite under laboratory conditions, simultaneously, different concentrations of ethanol added into the culture to investigate the effect of ethanol on gas production and microbial flora structure. Results show that when the ethanol concentration was 1%, the best methanogenesis was achieved at 44.86 mL/g, which was twice the gas production of 0% ethanol. Before and after gas fermentation, the composition and structure of the coal changed, the volatile matter and fixed carbon increased, and the ash decreased. The absorbance value at characteristic peaks of all functional groups decreased, new peaks were generated at 2,300/cm, and the peak value disappeared at 3,375/cm. Thus, microorganisms interacted with coal, consumed it, and produced new materials. The microbial flora changes during gas production were tracked in real time. 0.5 and 1% ethanol did not obviously change the bacterial communities but strongly influenced the archaeon communities, thereby changed the methane production pathway. In the absence of ethanol, Methanosarcina was continuously increasing with the extension of fermentation time, this pathway was the nutrient type of acetic acid. When ethanol was added, Methanobacterium gradually increased, the pathway was mainly hydrotropic type. In summary, adding ethanol can increase the coalbed methane production, change the structure and composition of coal, and facilitate the interaction of microbe with coal. Therefore, the methanogenic archaeon changes could help improve the methane-producing ability of lignite in the presence of ethanol.

Gallium oxide (Ga2O3) is an attractive semiconductor that is very suitable for deep ultraviolet (DUV) inspection. However, due to the existence of many types of oxygen vacancies in the amorphous Ga2O3 (a-Ga2O3) film, it greatly limits the performance of the a-Ga2O3-based photodetector. Here, we perform oxygen plasma treatment on the a-Ga2O3/p-Si photodetector to reduce the concentration of oxygen vacancies in the a-Ga2O3 film, so that the dark current is reduced by an order of magnitude (from 1.01 × 10−3 A to 1.04 × 10−4 A), and the responsivity is increased from 3.7 mA/W to 9.97 mA/W. In addition, oxygen plasma processing makes the photodetector operate well at 0 V bias. The response speed is that the rise time is 2.45 ms and the decay time is 1.83 ms, while it does not respond to the DUV illumination without oxygen plasma treating at a zero bias. These results are attributed to the fact that oxygen plasma treatment can reduce the Schottky barrier between a-Ga2O3 and the electrode indium tin oxide (ITO), which promotes the separation and collection efficiency of photo-generated carriers. Therefore, this work proposes a low-cost method to improve the performance of Ga2O3 film-based DUV photodetectors.

The aim of this study was to determine and compare a polyphenolic profile, antioxidant and antidiabetic activities between seeds and different growth periods leaves (from week 3 to 14) of three selected edible beans: yellow and black soyabean (Glycine max), as well as adzuki bean (Vigna angularis). Polyphenolic profile was determined by HPLC-ESI-TOF-MS and HPLC-DAD, antioxidant activity were analysed by ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)), FRAP (ferric reducing antioxidant power), and DPPH (2,2-diphenyl-1-picrylhydrazyl) tests. We also evaluated for their antidiabetic activity against α-glycosidase. The results showed that the leaves of three edible beans were a valuable source of polyphenolic substances. Furthermore, adzuki bean leaves contained significantly higher polyphenol content than their seeds. Thus, they exhibited stronger antioxidant and α-glucosidase inhibitory activities than seeds. However, soyabean contained more polyphenols than their leaves. Therefore, soyabean displayed a more positive effect on antioxidant and α-glucosidase inhibitory activities than their leaves.

Objective(s):Higher cellular reactive oxygen species (ROS) levels is important in reducing cellular energy charge (EC) by increasing the levels of key metabolic protein, and nitrosative modifications, and have been shown to damage the cardiac tissue of diabetic mice. However, the relation between energy production and heart function is unclear. Materials and Methods:Streptozotocin (STZ, 150 mg/kg body weight) was injected intraperitoneally once to mice that had been fasted overnight for induction of diabetes. After diabetic induction, mice received citrate (5 µg/kg) through intraperitoneal injection every other day for 5 weeks. The caspase-3, plasminogen activator inhibitor 1 (PAI1), protein kinase B (PKB), commonly known as AKT and phosphorylated-AKT (p-AKT) proteins were examined to elucidate inflammation and apoptosis in the heart. For histological analysis, heart samples were fixed with 10% formalin and stained with hematoxylin-eosin (HE) and Sirius red to assess pathological changes and fibrosis. The expression levels[AGA1] of marker proteins, tyrosine nitration, activity of ATP synthase and succinyl-CoA:3-ketoacid coenzyme A transferase-1 (SCOT), and EC were measured. Results:Intraperitoneal injection of citrate significantly reduced caspase-3 and PAI-1 protein levels and increased p-AKT level on the 5th week; EC in the heart was found to be increased as well. Further, the expression level, activity, and tyrosine nitration of ATP synthase and SCOT were not affected after induction of diabetes. Conclusion: Results indicate that application of citrate, a tricarboxylic acid (TCA) cycle intermediate, might alleviate cardiac dysfunction by reducing cardiac inflammation, apoptosis, and increasing cardiac EC.

There are few studies on the origins of coalbed gas in the northern Qinshui Basin, therefore, the coalbed gas in the Taiyuan Formation of the Sijiazhuang mine field in the northern Qinshui Basin was extracted to test the chemical composition and isotope of effluent gas from six coalbed gas wells, and thus the origins of coalbed gas can be explored. The results show that the average volume fractions of CH4, C2H6, CO2 and N2 in the coal seam of the northern Qinshui Basin are 94.98 %, 0.11 %, 0.25 % and 4.8 %, respectively, with no hydrocarbons heavier than ethane detected. The carbon and hydrogen isotopic values of methane of coalbed gas are within the range of -42.5 ‰ ~ -36.7 ‰ and - 200.06 ‰ ~ -196.33 ‰, respectively; and d13C (CO2) is between -17.1 ‰ and -15.1 ‰. The solution fractionation of groundwater is the main cause of the methane carbon isotope’s becoming lighter with increasing depths. The chemical composition and isotope test data of the Sijiazhuang mine field indicate that the coalbed gas has been subjected to the secondary transformation effect, mainly from coal cracking thermo genesis and supplemented by secondary biogenesis of CH4.

It is important to identify source information after a river chemical spill incident occurs. Among various source inversion approaches, a Bayesian-based framework is able to directly characterize inverse uncertainty using a probability distribution and has recently become of interest. However, the literature has not reported its application to actual spill incidents, and many aspects in practical use have not yet been clearly illustrated, e.g., feasibility for large scale pollution incidents, algorithm parameters, and likelihood functions. This work deduced a complete modular-Bayesian approach for river chemical spills, which combined variance assumptions on a pollutant concentration time series with Adaptive-Metropolis sampling. A retrospective case study was conducted based on the ‘landmark’ spill incident in China, the Songhua River nitrobenzene spill of 2005. The results show that release mass, place, and moment were identified with biases of −26.9%, −7.9%, and 16.9%, respectively. Inverse uncertainty statistics were also quantified for each source parameter. Performance, uncertainty sources, and future work are discussed. This study provides an important real-life case to demonstrate the usefulness of the modular-Bayesian approach in practice and provides valuable references for the setting of parameters for the sampling algorithm and variance assumptions.

Spruce chemithermomechanical pulp was treated with a laccase mediator system (LMS) and alkaline H2O2, and the whiteness and dye removal index of the long fibres fraction and fines fraction were compared. The long fibres fraction and fines fraction were treated separately with a LMS, and their whitenesses and strengths were tested. The results indicated that the lignin and extractives contents of the fines fraction were higher than that of the long fibres. Because of the strong adsorption capacity and higher reactive efficiency, the optimal laccase dosage of the fines fraction was lower than that of the long fibres. In the process of treatment using a LMS and alkaline H2O2, at the same laccase dosage, separate treatment of the long fibres fraction and fines fraction could improve pulp whiteness and pulp strength.

Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2-C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2-C7) generated in the bioconversion process were 0.01-1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane.

In order to obtain the adhesion force of fiber in a paper sheet easily, the relationships between internal bonding strength (IBS) and surface lignin content of masson pine CTMP treated with peracetic acid (PAA) have been investigated with XPS technique, and the surface morphology of fibers was also imaged by AFM. The results showed that the extent of lignin covered on the fiber surface was two times as high as that of whole pulp lignin, and the IBS was inversely proportional to surface lignin. The relationship between IBS and lignin coverage was formulated based on the experimental data. The mutual adhesion forces, cellulose-to-cellulose and lignin-to-lignin, were calculated using these equations, and the results were 28.69 mN/m and 2.487mN/m, respectively.

Valve microstructure is important during hot forging. Austenitic 21-4N steel is often used in exhaust valves. In this study, the microstructure evolution of the forging valve process was predicted using the internal state variables (i.e., average grain size, recrystallized fraction, and dislocation density) modus for 21-4N. First, 21-4N was subjected to hot compression tests on a Gleeble-1500D and static grain growth tests in a heating furnace. A set of uniform viscoplastic constitutive equations was established based on experimental data. Next, the determined unified constitutive equations were conducted in DEFORM-3D, and the microstructure evolution of 21-4N during forging was calculated. Finally, the simulation results of grain size evolution were validated via experiments. Results showed good consistency between the simulations and experiments. Thus, the models adequately predicted the microstructure evolution.

The in-die quenching is a key stage in the hot stamping volume production chain which determines the post-formed strength of lightweight alloy components, tool life, and hot stamping productivity. In this paper, the performance of in-die quenching, reflected by the quenching efficiency (the time of work-piece held within stamping dies) and die surface temperature during the simulated hot stamping process of AA6082, was experimentally and analytically investigated. A range of in-die quenching experiments were performed for different initial work-piece and die temperatures, quenching pressures, work-piece thickness, and die clearances, under hot stamping conditions. In addition, a one-dimensional (1D) closed-form heat transfer model was used to calculate the die surface temperature evolution that is difficult to obtain during practical manufacture situations. The results have shown that the in-die quenching efficiency can be significantly increased by decreasing the initial work-piece and die temperatures. Die clearances are required to be designed precisely to obtain sufficiently high quenching rates and satisfying post-formed strength for hot-stamped panel components. This study systematically considered an extensive variety of influencing factors on the in-die quenching performance, which can provide practical guides for stamping tool designers and manufacture systems for hot-stamping volume production.

The geologic conditions of No. 3 coal seams are similar to Sihe and Zhaozhuang Collieries, however, the gas production is significantly different. To better understand the effect of pores, by means of experimental measurements and quantitative analysis, the pore properties of high-rank isometamorphic anthracite were thoroughly studied. Our study showed that the pore structures were predominantly adsorptive, accounting for more than 88% of the specific surface area. The coal pores showed typical three-stage fractal characteristics at boundary points of 1 nm and 9 nm (7 nm of coal samples from Zhaozhuang Colliery), and the fractal dimension with 1–9 nm (or 1–7 nm), as being significantly larger than those measured outside the given ranges. Pores in samples from Sihe Colliery were mainly open spherical or ellipsoidal pores in shape; conversely, those from Zhaozhuang Colliery were mainly Y-shaped, V-shaped, or ‘ink-bottle’ type.