Experimental investigation of high temperature thermal-vibration characteristics for composite wing structure of hypersonic flight vehicles

A thermal-vibration test system is established by combining the high-temperature transient heating simulation system and vibration test apparatus, and this system can carry out experimental research on the thermal modal of high-temperature-resistant composite wing structure of hypersonic flight vehicles under high temperature environment with 1100°C. The vibration signals of the composite wing structure in high-temperature environments are transmitted to non-high temperature field by using self-developed extension configurations and then the vibration signals are measured and identified by using ordinary acceleration sensors. Based on a time-frequency joint analysis technique, the experimental data is analyzed and processed to obtain the key vibration characteristic parameters of composite wing structure, such as the natural frequency and mode shapes, in a thermal-vibration coupled environment up to 1100°C. The experimental results provide an important basis for the dynamic performance analysis and safety design of composite wing structure under high-temperature thermal-vibration conditions

Experimental investigation of high temperature thermal-vibration characteristics for composite wing structure of hypersonic flight vehicles

A thermal-vibration test system is established by combining the high-temperature transient heating simulation system and vibration test apparatus, and this system can carry out experimental research on the thermal modal of high-temperature-resistant composite wing structure of hypersonic flight vehicles under high temperature environment with 1100°C. The vibration signals of the composite wing structure in high-temperature environments are transmitted to non-high temperature field by using self-developed extension configurations and then the vibration signals are measured and identified by using ordinary acceleration sensors. Based on a time-frequency joint analysis technique, the experimental data is analyzed and processed to obtain the key vibration characteristic parameters of composite wing structure, such as the natural frequency and mode shapes, in a thermal-vibration coupled environment up to 1100°C. The experimental results provide an important basis for the dynamic performance analysis and safety design of composite wing structure under high-temperature thermal-vibration conditions

Preparation of an Efficient Oil-Spill Adsorbent Based on Wheat Straw

Acetylation of cellulose fiber extracted by methylbenzene/ethanol (2/1), sodium chlorite solution, and sodium hydroxide from raw wheat straw (RWS) was studied to examine its potential as an oil-spill adsorbent. Wheat straw cellulosic sorbent was produced by using acetic anhydride as an acetylating reagent and N-bromosuccinimide (NBS) as a catalyst. Effects of the volume ratio of acetic anhydride (from 6.25% to 57.5%), catalyst concentration (from 10 to 60 mM NBS), reaction temperature (from 50 to 120 °C), and reaction time (from 0.5 to 3 h) on oil-sorption properties were evaluated. The best oil absorbencies for diesel fuel, diesel oil slick, corn oil, and corn oil slick treatments were 24.21 ± 0.76, 22.39 ± 0.77, 25.61 ± 2.13, and 24.73 ± 1.19 g/g, respectively. Chemical composition and morphologic structure of RWS before and after acetylation were investigated and compared. Oil-absorption capacity, oil-retention ability, recyclability, and selectivity of RWS, pretreated wheat straw, and acetylated wheat straw were also discussed. The acetylated wheat straw demonstrated good potential for the utilization of agricultural residues as natural sorbents in oil cleanup

A Study of a Composite Biofilm Reactor for the Treatment of Mariculture Wastewater: Performance and Microbial Communities

Mariculture wastewater is one of the main sources of saline wastewater. This study used a waterfall aeration biofilm reactor combined with a sequencing batch reactor (WABR-SBR) to treat simulated mariculture sewage. Despite the high inhibition by salinity, the reactor maintained a high removal efficiency for organic matter and ammonium nitrogen. The ammonia nitrogen removal rate was greater than 99%, while that for nitrite, which is extremely toxic to farmed animals, was greater than 80%. Fourier transform infrared spectroscopy and scanning electron microscopy showed that salinity affected the surface structure and composition of biofilms, which became compact and secreted more solute to resist the impact of salinity. High throughput 16S rRNA sequencing revealed that the main phyla in the biofilms were Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes. Metagenomic annotation of genes further indicated nitrogen metabolism pathways under high salinity. The conclusions of this study can provide a theoretical foundation for the biological treatment of high-salt wastewater and provide a technical reference for further application of the WABR-SBR composite system

Combining a novel biofilm reactor with a constructed wetland for rural, decentralized wastewater treatment

A novel waterfall aeration biofilm reactor integrated with a constructed wetland (WABR-CW) system was developed to meet the challenge of decentralized wastewater treatment with a focus on nutrient removal. In a lab-scale experiment of 70 days, the WABR-CW showed a high removal efficiency for COD (85-98 %), NH4+-N (100 %), TN (60-90 %) and TP (85 %-95 %), even when different organic loading rates (OLR) were used. The CW was responsible for improving the overall performance in view of an increased nutrient removal. The CW offers denitrification capacity when the OLR is not optimal for the WABR. Based on the lab-scale experiment, a pilotscale WABR-CW was built and tested for aquaculture wastewater treatment and reuse. A total of 63 m3 wastewater was treated of which 56.7 m3 was reused. Furthermore, the microbial structure of the WABR-CW system was investigated. A metabolic analysis highlighted the N and C metabolic pathways and functional genes distribution in the WABR-CW system. Next generation sequencing not only linked the pollutants removal performance and microbial encoding genes but also disclosed the potential ability of WABR-CW to treat more polluted and more complex wastewater. The outcomes of this study provide scale-up results and a better understanding of the functioning of the WABR-CW.A novel waterfall aeration biofilm reactor integrated with a constructed wetland (WABR-CW) system was developed to meet the challenge of decentralized wastewater treatment with a focus on nutrient removal. In a lab-scale experiment of 70 days, the WABR-CW showed a high removal efficiency for COD (85-98 %), NH4+-N (100 %), TN (60-90 %) and TP (85 %-95 %), even when different organic loading rates (OLR) were used. The CW was responsible for improving the overall performance in view of an increased nutrient removal. The CW offers denitrification capacity when the OLR is not optimal for the WABR. Based on the lab-scale experiment, a pilotscale WABR-CW was built and tested for aquaculture wastewater treatment and reuse. A total of 63 m3 wastewater was treated of which 56.7 m3 was reused. Furthermore, the microbial structure of the WABR-CW system was investigated. A metabolic analysis highlighted the N and C metabolic pathways and functional genes distribution in the WABR-CW system. Next generation sequencing not only linked the pollutants removal performance and microbial encoding genes but also disclosed the potential ability of WABR-CW to treat more polluted and more complex wastewater. The outcomes of this study provide scale-up results and a better understanding of the functioning of the WABR-CW.A