The Influence of Track Structure Parameters on the Dynamic Response Sensitivity of Heavy Haul Train-LVT System

Background: In order to study the applicability of Low Vibration Track (LVT) in heavy-haul railway tunnels, this paper carried out research on the dynamic effects of LVT heavy-haul railway wheels and rails and provided a technical reference for the structural design of heavy-haul railway track structures. Methods: Based on system dynamics response sensitivity and vehicle-track coupling dynamics, the stability of the upper heavy-haul train, the track deformation tendency, and the dynamic response sensitivity of the vehicle-track system under the influence of random track irregularity and different track structure parameters were calculated, compared and analyzed. Results: Larger under-rail lateral and vertical structural stiffness can reduce the dynamic response of the rail system. The vertical and lateral stiffness under the block should be set within a reasonable range to achieve the purpose of reducing the dynamic response of the system, and beyond a certain range, the dynamic response of the rail system will increase significantly, which will affect the safety and stability of train operation. Conclusions: Considering the changes of track vehicle body stability coefficients, the change of deformation control coefficients, and the sensitivity indexes of dynamic performance coefficients to track structure stiffness change, the recommended values of the vertical stiffness under rail, the lateral stiffness under rail, the vertical stiffness under block, and the lateral stiffness under block are, respectively 160 kN/mm, 200 kN/mm, 100 kN/mm, and 200 kN/mm.

Preparation of Nanostructured SnO2-NiO Composite Semiconductor for Gas Sensor Applications

Electro spinning technology combined with chemical precipitation method and high-temperature calcination was used to prepare SnO2-NiO composite semiconductor nanofibers with different Sn content. Scanning electron microscope (SEM), X-ray diffractometer (XRD) and energy dispersive X-ray spectrometer (EDS) were used to characterize the morphology, structure and content of various elements of the sample. Using ethanol as the target gas, the gas sensing properties of SnO2-NiO nanofibers and the influence of Sn content on the gas sensing properties of composite nanofibers were explored. The research results show that SnO2-NiO composite nanofibers have a three-dimensional network structure, and the SnO2 composite can significantly enhance the gas sensitivity of NiO nanofibers. With increase of SnO2 content, the response sensitivity of composite fibers to ethanol gas increases, and the response sensitivity of composite nanofibers with the highest response to ethanol gas with a volume fraction of 100×10-6 at the optimal working temperature of 160℃ are13.4;It is 8.38 times the maximum response sensitivity of NiO nanofibers. Compared with the common ethanol gas sensor MQ-3 on the market, SnO2-NiO composite nanofibers have a lower optimal working temperature and higher response sensitivity, which has certain practical application value

Response of Root Development and Nutrient Uptake of Two Chinese Cultivars of Hybrid Rice to N and P Fertilization in Sichuan Province, China

Chemical fertilization helped modern agriculture in enhancing grain yield to overcome food security. The response of chemical fertilization for higher hybrid rice production is highly dependent on optimal fertilization management in paddy fields. To assess such responses, the current research examined the yield, root growth, and expression of related genes responsible for stress metabolism of N and P in two hybrid-rice cultivars Deyou4727 (D47) and Yixiangyou2115 (Y21). The experiment followed four N (N0, N60, N120, and N180 kg/ha) and P (P0, P60, P90, and P120 kg/ha) fertilizer levels. The D47 was more sensitive toward nitrogen application, which resulted in comparatively higher biomass and yield, while Y21 was more sensitive toward phosphorus application. The grain yield was more sensitive to nitrogen application in D47 but not in Y21. Our findings were corroborated by gene expression studies of glutamine synthetase OsGS1;1 and OsGS1;2 and phosphate starvation-related genes PHR1 and SPX, which also concluded D47 response sensitivity towards N application and Y21 response sensitivity toward P application. In the case of root numbers, D47 was less sensitive in low nitrogen application N0-N60, but the overall nutrient response difference was significantly higher due to the deep rooting system as compare to Y21. The higher yield, low N and P uptake, and versatile root growth of D47 make it suitable to reduce unproductive usage of N and P from paddy fields, improving hybrid rice productivity, and environmental safety in the Sichuan basin area of China.