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 recent years, digital class D power amplifiers have attracted widespread attention in the audio electronics field due to their high efficiency and seamless integration with digital audio sources. As one of the crucial digital signal processing modules in digital class D amplifiers, the Sigma-Delta modulator plays a pivotal role for digital audio signal processing. The noise-shaping characteristic of the Sigma-Delta modulator can reduce the implementation cost of the power amplifier system while maintaining or even improving the output signal-to-noise ratio of the system, and can suppress the noise introduced by some signal transmission paths. Firstly, the working principle and mainstream architecture of digital D-class power amplifiers were summarized. Then, based on the basic principle of Sigma-Delta modulators, the design schemes of Sigma-Delta modulators used in digital D-class power amplifiers in recent years were discussed, with a focus on the architecture design and noise transfer function design of Sigma-Delta modulators. Finally, the research and development of Sigma-Delta modulators for digital D-class power amplifiers were summarized.

The tension string system with concentrated viscous damping belongs to a hybrid dynamic system in mechanical models. Approximate methods are typically used to solve its inherent problems for engineering applications. In order to further clarify the vibration characteristics of the system, two centrally damped symmetrical damping string systems were taken as the basic research object, and their complex eigenvalues were solved analytically. The complex frequency equation and the eigenvalue expression of the system were derived, and the transformation of the complex frequency equation beyond the function form was treated as algebraic form, and the explicit solution of the complex eigenvalue of the system was given by the algebraic equation. The structure and properties of the complex eigenvalues of the system were analyzed, and the variation of vibration characteristics with damping coefficient was discussed. The results show that the eigenvalue solution of the system can be divided into three branches, in which the real part of the eigenvalue(the inverse is the decay rate) does not change with the order of the system motion, but the imaginary part of the eigenvalue(the frequency) increases with the order of the motion. The decay rate curves corresponding to each solution branch increase first and then decrease with the damping coefficient, and in the damping range of the decay rate curve, the frequencies of each order of the system are equal.

Addressing the challenge of insufficient accuracy in building regional cultural heritage 3D models using single-image modeling techniques, a method for optimizing regional ancient architectural three-dimensional models through the fusion of laser and imagery was proposed. Initially, imagery data of the target area was acquired through drone-based cross-flight aerial photography combined with close-range photography. Subsequently, laser scanning data was obtained using a 3D laser scanner to cover blind spots from drone aerial photography. Then, the laser scanning data was fused and registered with the imagery data to generate a complete point cloud model of the target area, which is then used to reconstruct a refined 3D model of the regional cultural heritage. Finally, the superiority of the proposed method was validated through error analysis of the fused heterogeneous data and comparative analysis of accuracy and texture completeness with single-image modeling results. The results indicate that the fused heterogeneous data achieves high fitting accuracy, and the resulting regional ancient architectural 3D model exhibits high accuracy and texture completeness, thereby providing valuable technical reference for the detailed modeling of ancient architectural complexes within the target scope and holding broad application prospects in enhancing the digital archive storage of ancient architectural three-dimensional models.

The scientific extraction of urban built-up area information and the exploration of the spatial-temporal characteristics of urban expansion have significant relevance for urban planning and management. The local-optimal thresholding method was refined for the quantitative extraction of urban built-up area information within the Baiyangdian Basin, and the extraction process utilized PANNDA nighttime light data and Landsat series data from four periods: 1990, 2000, 2010, and 2020. Subsequently, an analysis of the spatial-temporal characteristics of urban built-up area expansion in the basin over the past 30 years was conducted using the urban expansion index and landscape index. The results show the optimized local-optimal thresholding method is successfully used to extract the data of the built-up areas in the basin for all phases, and it is confirmed that the method exhibits enhanced applicability compared to its pre-optimization state. The urban built-up area in the Baiyangdian Basin experienced significant expansion throughout the study period, with a growth rate of 154.48%. The sizes of the built-up areas across the 35 cities in the basin exhibited high heterogeneity. Temporally, the expansion of urban built-up areas predominantly exhibited an accelerating trend, with a widening disparity in the pace of expansion among the cities within the basin. Spatially, the built-up area to the left of the Zhengding-Zhuozhou line was less developed than that to the right. Notable expansion trends were observed in municipal districts or county-level cities such as Lianchi District, Jingxiu District, and Gaobeidian City. Based on the results of the landscape index, the expansion of urban built-up areas in Baiyangdian Basin shows the spatial characteristics of “dispersion-fusion” during the study period, and the boundary of built-up areas showed the evolution characteristics of “regular-complex-regular”.

The Loess Plateau, as a natural ecological barrier in the western region of China, has made positive contributions to the sustainable development of the nation. The governance and restoration of the ecological environment on the Loess Plateau (Gansu region) plays a critical role in the implementation of China’s ecological civilization construction strategy. To monitor the changes in forest resources on the Loess Plateau (Gansu region) from 2008 to 2018, based on cloud platform, Landsat, PALSAR, and terrain data were integrated to explore the advantages of spectral index, backscatter, texture, and terrain features in obtaining forest resource information. The random forest feature selection algorithm was utilized to obtain the spatiotemporal distribution of forest cover in the study area for 10 years, and factor detection was conducted using geographic detectors. The results indicate that the random forest feature selection algorithm can effectively screen important feature information, with an overall accuracy of 91.88% and a Kappa coefficient of 0.91. The experimental scheme that integrates Landsat, PALSAR, and terrain data presents significantly higher accuracy compared to the forest classification results using a single data source. The overall accuracy of the four classification results is 86.65%, 88.23%, 90.15%, and 89.86% respectively. Over the past 10 years, the net increase in forest area in the study area is 0.60×10⁴ km². The areas with increased forests are primarily distributed in the central and eastern parts of Qingyang City, Pingliang City, Tianshui City, and the western region of Linxia Hui Autonomous Prefecture, while forest degradation primarily occurs in the southwestern part of Dingxi City and the central and eastern areas of Linxia Hui Autonomous Prefecture. In single-factor detection, land use type is the dominant factor in forest cover change, and the spatial distribution of suitable soil type and the auxiliary effect of rainfall provide favorable natural conditions for the survival rate of afforestation and the healthy growth of forests.

Henan Province has abundant geothermal resources, with the northern and central regions having undergone extensive exploration and large-scale development. However, the southern region of Henan has been subject to limited exploration efforts, resulting in a scarcity of drilling data. Consequently, research on its structural characteristics, stratigraphic distribution, geothermal geological characteristics and resource potential is relatively underdeveloped. This knowledge gap poses challenges in meeting the demands for industrialization and large-scale development. Based on regional geological characteristics and two-dimensional seismic interpretation results, the research on geothermal geological characteristics, resource evaluation and favorable area prediction in Zhumadian area were carried out on the basis of previous studies. The results show that Zhumadian structure is located in five secondary structural units: Wuyang Depression, Zhumadian-Huaibin Depression, Pingyu Uplift and Changshan uplift in the southwest of Zhoukou Depression and Biyang Depression in the east of Nanxiang Basin. In Zhumadian area, the geothermal geological conditions are poor in Zhengyang and Chishan, which are located in the uplift area of Changshan Mountain. There are three sets of stratified heat reservoirs in Neogene, Paleogene sandstone and Cambrian-Ordovician carbonate rocks in this area, and the total static resources are about 115×10¹⁵ kJ. It is predicted that Biyang County urban area, Xincai County urban area and the west of Yicheng District are the most favorable areas for geothermal resources development, with moderate depth of heat storage, large water inflow and high temperature.

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.

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.

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.