Latest ArticlesIn order to improve the efficiency of air transportation, reduce transportation costs and carbon emissions, the evolutionary game method was adopted to explore the influencing factors of the cargo alliance between the government and airlines. The system dynamics model (SD) was used to conduct simulation experiments on the game evolution process. The results indicate that the strategic choices between airlines are influenced by investment costs and alliance benefits, while the government’s strategic choices are influenced by factors such as the carbon emission penalty coefficient paid by airlines, carbon tax subsidy amounts, social benefits, and regulatory costs. In the long run, the government should establish a dynamic subsidy mechanism and increase the diversity of subsidies to enhance the innovation and core competitiveness of airlines.
To explore the effects of weak mineralized water and straw separation treatment on soil water and salt transport, through indoor soil column infiltration and evaporation test, the distribution of water and salt in soil under the irrigation condition of fresh water and slightly mineralized water with different salinity (1, 2, 3 g/L) at the buried depth of 0, 10 and 20 cm of straw interlayer was studied. The results show that there is a power function relationship between the wetting front and the infiltration time at the infiltration stage. The water infiltration rate increases with the increase of salinity, and the cumulative infiltration decreases with the increase of salinity. Kostiakov model and Philip model are used to fit the cumulative infiltration amount and infiltration time respectively, and the fitting results are good. During the evaporation stage, the straw interlayer has a significant water retention effect on the soil below the buried depth, and the vertical distribution of soil salinity shows a significant low desalination effect, and salt accumulates in the straw interlayer. When the salinity of irrigation water is 2 g/L and the depth of straw layer is 10 cm, it is conducive to soil bottom desalting, and has a better effect of promoting soil water infiltration and water retention. The research can provide basis and reference for weak mineralized water irrigation and the exploitation and utilization of straw resources.
The displacement response of a bridge is identified as a fundamental condition for the structural health monitoring and safety assessment of bridge structures. In order to fully leverage the advantages of machine vision for measuring structural displacements and to enhance its applicability, a structural displacement monitoring method based on the pinhole camera model was proposed. Sparse optical flow was employed to track structural feature points, achieving sub-pixel level image displacements. By employing the optical geometric relationships of camera imaging, an analytical solution was established between real-world displacements and image displacements. The image displacements were then substituted into algebraic relationships to obtain the true structural displacements. In the indoor experiments on dynamic load displacement identification of a simply supported bridge model, compared to the measurements obtained using a linear variable differential transformer displacement meter, the proposed method achieves a maximum error within 6% for pitch angles up to 30° and yaw angles up to 35°, thereby meeting the application requirements for monitoring the displacement deformations of bridge structures.
The quantitative monitoring and evaluation of the terrestrial ecological environment status helps to understand the changes in ecosystems and their driving factors, and is of great significance for the government to guide regional ecological environment management, achieve ecological protection and socio-economic coordinated development. Based on long-term multi-source satellite remote sensing data, a land ecological environment status index (LESI) evaluation model was constructed by coupling five indicators including greenness, heat, humidity, dryness, and air pollution using covariance principal component analysis. Four strategies, including Augmented Dickey Fuller (ADF) test, Biplot biplot, correlation analysis, and cross validation, were used to demonstrate the good stationarity, rationality, comprehensive representativeness, and regional adaptability of the model. On this basis, the spatio-temporal characteristics and evolution patterns of the land eco-environment status (LES) in the the Taihu Lake Basin from 2001 to 2021 were assessed, the driving factors of LES changes were discussed, and the contributions of climate change and human activities were quantified. The results show that the eco-environment quality of the the Taihu Lake Basin is declining first and then stable. The average annual LESI decreases significantly from 0.639 in 2001 to 0.523 in 2009 (-18.2%), and then tends to be stable. The spatial-temporal variation of LESI in Taihu Lake Basin is obviously different. The area where the ecological environment quality remains stable or improved (68.8%) is significantly larger than the area where the ecological environment quality is declining (31.2%), of which Hangzhou and Huzhou have the best eco-environment quality and remain stable. Shanghai and Suzhou are relatively poor and have significant fluctuations. The contributions of temperature, precipitation and night light to LESI are 0.03, 0.19 and 0.78, respectively, indicating that the eco-environment changes in the the Taihu Lake basin in recent 21 years are mainly dominated by human activities, while only some forest mountain areas and wetland areas are affected by climate change. The LESI model established in the study can effectively monitor and quantitatively evaluate changes in the eco-environment, providing scientific support for the government to formulate ecological environment protection policies and promote high-quality development.
The Box-Behnken experimental design and response surface methodology were employed to optimize the preparation of the aspirin micro-porous osmotic pump tablets. The core of the tablet was prepared with aspirin and β-CD inclusion, then osmotic pump tablets were obtained by coating a layer of cellulose acetate containing PEG 4000 as porogenic agent. The in vitro release test shows that the aspirin inclusion complex microporous osmotic pump tablets prepared by this process has a cumulative release rate of 1.5% and 1.6% within 0~2 h in artificial gastric juice compared to commercially available aspirin enteric coated tablets. After adjusting the release medium to pH 6.8, there is no significant difference in the cumulative drug release between the two formulations at 10 h. And the inclusion complex microporous osmotic pump tablet shows zero order release and complete release within 12 h(cumulative release rate > 90%), indicating the possibility of reducing drug damage to the gastric mucosa.
The current seismic toughness assessment is mainly aimed at the impact of a single earthquake on a single building, it is difficult to consider the seismic toughness assessment of different buildings in the same area. The research area was divided into grids according to 500 m×500 m, and seismic risk analysis was carried out. Six indexes, including the cost of building defense, damaged area of different degrees, direct economic loss of buildings, repair time, repair cost and casualties, were taken as the evaluation indexes of earthquake resilience. Analytic hierarchy process (AHP) was used to determine the weights of each index, and an earthquake resilience evaluation model based on grid and radar map was established and applied to Chengdu City. The results show that the earthquake toughness of Chengdu City is normal when the fortification is not upgraded. After upgrading the fortification, the cost of fortification increases by 45.95%, and the damaged area, the direct economic loss of the house, the repair time, the repair cost and the number of casualties decreases by 26.25%, 37.75%, 45.1%, 44.24% and 48.18%, respectively. Through comparative analysis of the model data, it is found that after upgrading the fortification, the comprehensive benefit of earthquake resilience of Chengdu City buildings is increased by 40.8%, the disaster loss is greatly reduced, and the improvement effect is obvious.
Gaseous detonation is a method to obtain nanomaterials in a short time by gas explosion, which has been successfully applied to the preparation of carbon nanomaterials and oxides. Compared with other nanomaterials preparation methods, gaseous detonation method has the advantages of high efficiency, convenience, high yield and green environmental protection. The instrumentation and operation procedures required for the preparation of nanomaterials by gaseous detonation were described. Secondly, the morphology, structure, and performance characteristics of carbonaceous nanomaterials and metal oxide nanomaterials prepared by gaseous detonation were presented. At the same time, the current status of the growth mechanism of nanomaterials was analysed and summarized. Moreover, the progress of the research on nanomaterials prepared by gaseous detonation in the areas of photocatalysis, electromagnetic wave absorption, and friction resistance was summarized. Finally, the application potential and technological prospect of the gaseous detonation method and the nanomaterials prepared by the method were discussed, which can provide a useful reference for the industrialised large-scale synthesis of nanomaterials by the gaseous detonation method.
In order to study the molecular weight and molecular structure changes of asphalt under ultraviolet aging and the mechanism of their effects on macro properties, gel permeation chromatography and nuclear magnetic resonance tests were carried out on four commonly used asphalt, respectively. The molecular weight composition changes, such as molecular weight and molecular relative mass distribution, and the molecular structure composition changes, such as hydrogen spectrum, carbon spectrum, hydrogen atom content and molecular structure parameters were studied. On the basis of macroscopic rheological tests, the molecular composition of asphalt rheological properties was characterized by correlation analysis, and the molecular mechanism of ultraviolet aging macroscopic properties was analyzed. The results show that ultraviolet aging causes the agglomeration of molecules in asphalt, small molecules decreases and aggregates into large molecules, and the molecular weight distribution boundary narrows gradually. From the changes of hydrogen atoms and molecular structure parameters, it can be seen that the alkyl substituents on the aromatic ring in the asphalt increase after ultraviolet aging, resulting in the increase of the volume and stability of the aromatic ring, and the increase of molecular backbone stiffness. On the macro level, the elastic properties of asphalt increase. The phase angle, rutting factor, irrecoverable compliance and recovery rate of asphalt before and after ultraviolet aging were obtained by macroscopic rheological tests. The correlation analysis shows that the rheological properties are most affected by condensation degree parameters, substitution rate of peripheral hydrogen, average molecular weight and branched degree of alkyl chain.
In order to study the effect of basalt fiber on the porosity of recycled concrete under salt erosion, the internal variation of concrete was analyzed by scanning electron microscopy, and a linear regression model was established between the porosity of concrete and the number of dry and wet cycles, the height of penetration, the compressive strength and the splitting tensile strength. A fully connected neural network (FCNN) model was established for the penetration height under different soaking ages and fiber content for predicting the corrosion resistance life of basalt fiber regenerated concrete under salt erosion conditions. The results show that the porosity of concrete increases gradually with the erosion age increasing, and the appropriate addition of basalt fiber can significantly reduce the porosity of concrete, and the improvement effect is most significant when the fiber content is 1.0%. With fiber content increasing, the salt permeability resistance of recycled concrete increases, and permeability height decreases. When the fiber content is 1.0%, the best compressive strength and splitting tensile strength are obtained. The fully connected neural network model has a good effect and provides a reliable reference for the life prediction of basalt fiber recycled concrete.
In order to clarify the reservoir applicability of different acid systems, understand the influence of reservoir acid rock etching morphology on fracture conductivity, and give the optimal slug combination method for different horizons, acid erosion fracture conductivity experiments were carried out in the carbonate reservoirs of Sichuan and Chongqing, the results show that the conductivity of slug combinations between different acid systems to the dolomite of the Maokou Formation after acid etching is higher than that of the limestone. The morphology of acid-etched fractures after acid-etching is different between different single-acid systems, in which steering acid has extremely deep grooves after etching, and the grooves of authigenic acid are the shallowest. For Maokou Formation, when the alternation between gelling acid and fracturing fluid and the alternation between gelling acid and authigenic acid is tertiary, the conductivity is the highest, and the conductivity reaches 4.53 μm2·cm at 60 MPa after tertiary alternation between gelling acid and authigenic acid. The conductivity of Qixia Formation and Dengying Formation is the highest when secondary alternation of fracturing fluid and gelling acid was selected, and the conductivity of Qixia Formation and Dengying formation are 6.72 μm2·cm and 7.47 μm2·cm at 60 MPa, respectively. In the Sichuan Chongqing exploration area, on-site application and in-depth investigation were conducted to verify the acid corrosion fracture conductivity of the acid solution. The results show that the acid corrosion effect is good after the acid solution entered the well, and the gas testing effect after the transformation is 208×104 m3/d, achieving the expected increase in production. It provides theoretical and experimental guidance for acid fracturing technology of carbonate reservoirs in Sichuan and Chongqing.