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Focusing on the problem of unclear ray-traced spots and their distribution rules in the design process of the Herriott cell, first, the characteristics of long-optical-path gas absorption cells were analyzed, and the calculation method of basic cavity length and the effective optical path of Herriott gas absorber cells were studied. Second, according to the transmission characteristics of geometric optics, a physical model of light transmission in Herriott cells was established via the LightTools software. Finally, simulation analysis was performed on Herriott cells with 5- and 14.4-m optical paths separately, determining the quantitative relationship between d/f and the number of spots reflected on the concave mirror, and optimizing the effective optical path and output laser energy of the Herriott cells. Through research analysis, the sizes and distribution positions of concave mirror spots in the Herriott cells were identified, as well as the factors affecting the number of reflections. It was also found that the number of reflected spots gradually decreases as d/f increases, revealing the light-tracing results and its spot distribution rule on the mirror surface, as well as verifying the accuracy of the theory. The findings of this study provide a basis for the optical path system design and optimization for Herriott cells with different optical path lengths. [ABSTRACT FROM AUTHOR]

Proanthocyanidin antioxidant was first selected for study, and the inhibitory effect of proanthocyanidin and the optimal mass ratio of 6 mass% were obtained through temperature-programmed experiments. To compensate for the inhibitory effect and action time of a single antioxidant, a composite inhibitor with a physical and chemical synergistic effect was obtained through compounding with sodium polyacrylate, a superabsorbent resin, which improved the inhibitory effect on the spontaneous combustion of long-flame coal. In addition to the temperature-programmed experiments, the spontaneous combustion of long-flame coal was researched through a thermogravimetric (TG)–differential scanning calorimetric (DSC) experiment, and the optimal compound ratio of proanthocyanidins/sodium polyacrylate was determined to be 1:4. Under this ratio, the inhibition rate was close to 88% when the coal temperature ranged from 40 to 130 °C. The TG–derivative TG curve moved to the high-temperature region, and the composite inhibitors improved the characteristic temperature of raw coal and reduced its mass loss. The temperature corresponding to the peak value of the DSC curve increased, and the maximum heat release power was reduced. Fourier-transform infrared spectroscopy experiments revealed that the intensity of the hydroxyl peaks was reduced with the addition of composite inhibitors, and the peak intensity of methyl and methylene was lower than that of the raw coal. The inhibition characteristics of the composite inhibitor were thus obtained through a study of the change pattern of functional groups of coal samples during the heating process. [ABSTRACT FROM AUTHOR]

In order to explore the characteristics of spontaneous combustion of Jurassic coal in northern Shaanxi with low metamorphic degree and high coke content, DSC differential scanning calorimeter and diffuse in situ infrared spectroscopy experiment were used to study and analyze the dynamic evolution law and interaction relationship between macroscopic thermal effect and microstructure in the spontaneous combustion process of different coal seams in northern Shaanxi. The results show that there are three characteristic temperature points in the heat flow curve during the spontaneous combustion of Jurassic coal in northern Shaanxi, which can be divided into four stages according to the characteristic temperature points. It was found that the consumption and production of functional groups in Jurassic coal oxidation process were mainly in the absorption bands of aliphatic hydrocarbon, aromatic hydrocarbon and oxygen-containing functional groups, and CH3, CH2, C–H, OH and C=O were the most active key functional groups in the process of coal oxidation. The dynamic correlation degree between heat flux intensity and key active groups is established by using dynamic grey correlation mathematics method. It is concluded that C=O bond has the highest correlation with heat flow intensity during coal oxidation, and has the greatest influence on heat flow intensity. The correlation values of the active groups CH3 and CH2 are second only to the C=O bond, and they are easy to react with oxygen, accompanied by the reaction heat. Although the correlation degree between C–H and OH bond is lower than that of C=O, CH3 and CH2 bond, the correlation degree value is also high, and has certain contribution to the coal reaction heat. These research results have important guiding significance for the development of targeted inhibitors for Jurassic coal spontaneous combustion disaster in northern Shaanxi. [ABSTRACT FROM AUTHOR]

Coalfield fire areas are widespread in the world, seriously threating the local ecological environment and the economic development. The complexity of occurrence and evolution challenges the scientific prevention and control of coalfield fire. Taking the Tanyaoqu coalfield fire area in China as the object, a physical model was established, and variations of temperature field during coal seam combustion were investigated. Moreover, the distribution of flow field in the fracture channel was examined by numerical simulation. The results indicated that the temperature field in coal seam expands faster in the dip direction than in strike direction, and this is related to the development pattern of fracture channel. The relationship between temperature and time was conformed to the logistic model, while the temperature decreased exponentially with extension of horizontal distance. The temperature variation in rock strata was similar, but lags behind those in the coal seam. Furthermore, at the initiative stage of coalfield fire, both the inflow and outflow happened in the initial fracture. It turned to be the air intake channel when new fractures formed. When the combustion center moved forward, the ventilation quantity decreased until the new fractures formed. Meanwhile, the ventilation quantity increased rapidly when the U-shape channel formed from the interval fractures. The variation of flow field in fracture channel provides a view that the air supply in coalfield fire area changes periodically with the closure and generation of fracture channels, which will influence the evolution of coalfield fire. These are of great significance for revealing the evolution process of coalfield fire. [ABSTRACT FROM AUTHOR]

In this paper we introduce an image-based virtual exhibition system especially for clothing product. It can provide a powerful material substitution function, which is very useful for customization clothing-built. A novel color substitution algorithm and two texture morphing methods are designed to ensure realistic substitution result. To extend it to 3D, we need to do the model reconstruction based on photos. Thus we present an improved method for modeling human body. It deforms a generic model with shape details extracted from pictures to generate a new model. Our method begins with model image generation followed by silhouette extraction and segmentation. Then it builds a mapping between pixels inside every pair of silhouette segments in the model image and in the picture. Our mapping algorithm is based on a slice space representation that conforms to the natural features of human body. [ABSTRACT FROM AUTHOR]

Liquid carbon dioxide has an excellent ability of endothermic cooling and inhibition on coal fire, which was an effective coal spontaneous combustion prevention technology. To analyze the oxidation characteristics and variation of apparent activation energies, a carboniferous–permian coal sample was investigated in O2/N2 and O2/CO2 atmospheres by the coal spontaneous combustion oxidation and the Fourier transform infrared spectroscopy experiments. The results indicated that with temperature, carbon monoxide (CO) concentration and oxygen (O2) consumption rate increased. While O2 concentration decreased, CO concentration and oxygen consumption rate reduced. At the same O2 concentration, the oxygen consumption rate and CO concentration on the O2/CO2 atmospheres were less than on the O2/N2 atmospheres. Therefore, O2 concentration reduced, or added CO2 significantly inhibited coal oxidation. As the temperature elevated, the apparent activation energy gradually increased. Furthermore, the apparent activation energy increased when the oxygen concentration reduced in the physical–chemical adsorption stage and the slow oxidation stage. In the rapid oxidation stage, the apparent activation energy lessened with increase in oxygen concentration. Through correlation analysis, the key functional groups in the physical–chemical adsorption stage were hydroxyl, C–O, –COO–, and aliphatic hydrocarbons. During the slow oxidation, the key functional groups were –COO– and aliphatic hydrocarbons. The key functional groups in the rapid oxidation stage were hydroxyl and C–O. [ABSTRACT FROM AUTHOR]