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991.
992.
Numerical analyses have been performed to study the influence of fast depressurization on the wake flow field of the base-bleed unit (BBU) with a secondary combustion when the base-bleed projectile is propelled out of the muzzle. Two-dimensional axisymmetric Navier-Stokes equations for a multi-component chemically reactive system is solved by Fortran program to calculate the couplings of the internal flow field and wake flow field with consideration of the combustion of the base-bleed propellant and secondary combustion effect. Based on the comparison with the experiments, the unsteady variation mechanism and secondary combustion characteristic of wake flow field under fast depressurization process is obtained numerically. The results show that in the fast depressurization process, the variation extent of the base pressure of the BBU is larger in first 0.9 ms and then decreases gradually and after 1.5 ms, it remains basically stable. The pressure and temperature of the base-bleed combustion chamber experience the decrease and pickup process. Moreover, after the pressure and temperature decrease to the lowest point, the phenomenon that the external gases are flowing back into the base-bleed combustion chamber appears. Also, with the decrease of the initial pressure, the unsteady process becomes shorter and the temperature gradient in the base-bleed combustion chamber declines under the fast depressurization process, which benefits the combustion of the base-bleed propellant. 相似文献
993.
对卫生间硅酸钙板轻质隔墙上采用瓷砖饰面系统进行了相关应用性研究,讨论了硅酸钙板厚度、界面处理、防水处理以及粘贴材料等对系统粘结力的影响,提出了在硅酸钙板轻质墙体上进行瓷砖饰面的可靠施工方案。 相似文献
994.
A new kind of warehouse layout problem, multiple-level warehouse layout problem (MLWLP), is investigated. Both horizontal and vertical travel costs need to be considered when making a layout. In the problem, unit travel costs are item-dependent and different items can be mixed in a cell. An IP model is proposed, which is shown to be NP-hard. An effective assignment method is presented and genetic algorithm heuristics developed. Extensive computational experiments are conducted to verify the effectiveness of the algorithms. 相似文献
995.
996.
Yannan Zhang Peng Dong Jinbao Zhao Xue Li Yingjie Zhang 《Ceramics International》2019,45(9):11382-11387
The porous Fe2TiO5 particles are successfully synthesized through a facile one step solution combustion method. The Fe2TiO5 negative materials exhibit remarkable electrochemical performance with discharge capacities of 371.4?mAh g?1 at the 100 th cycle, and display promising rate stability with discharge capacities 76.6?mAh·g?1 at a high current density of 3.2?A?g?1. In addition, the mechanism of electrochemistry reaction is illustrated by the CV, raman and EIS measurements, the irreversible capacity mainly causes from the irreversible lithium insertion at 1.8?V. The results indicate that the one step solution combustion synthesis of porous Fe2TiO5 is a promising strategy for developing low-cost and high-performance Ti-based negative materials. 相似文献
997.
Runqiang Yu Bining Xue Jiaqi Liao Wanting Zhu Jiayuan Fu 《Fullerenes, Nanotubes and Carbon Nanostructures》2021,29(1):28-38
AbstractIn the present study, lanthanum modified carbon nanotubes (La-CNTs) were prepared by the impregnation method and used as adsorbents to remove oxytetracycline (OTC) from aquaculture wastewater. La-CNTs were characterized by SEM, EDS, XRD, BET analysis. The effects of adsorbent dosage, concentration of OTC, adsorption time, pH and interfering ions on the adsorption of OTC by La-CNTs were investigated. The optimum adsorbent dosage, OTC concentration, adsorption equilibrium time and pH for OTC adsorption by La-CNTs are 0.03?g, 20?mg/L, 180?min and 7, respectively. The outcome of the kinetics studies showed a significant linear correlation between the experimental results and the quasi-second-order kinetics model. As an adsorption isotherm model, the Langmuir model showed a very good consistency with the adsorption of OTC by La-CNTs, as the maximum adsorption quantity reached 117.23?mg/g. Through the thermodynamic analysis showed that the adsorption of OTC by La-CNTs was an endothermic process of entropy increase, which occurs spontaneously. The predominant forces promoting this adsorption were van der Waals force, π-π electron donor-acceptor interaction, and electrostatic interaction. 相似文献
998.
Effects of different osmo‐dehydrofreezing treatments on the volatile compounds,phenolic compounds and physicochemical properties in mango (Mangifera indica L.) 下载免费PDF全文
Jin‐Hong Zhao Fang Liu Xue‐Li Pang Hong‐Wei Xiao Xin Wen Yuan‐Ying Ni 《International Journal of Food Science & Technology》2016,51(6):1441-1448
The influences of different osmotic solution pretreatments (sucrose, glucose and maltose with concentration of 45%) on the volatile compounds, phenolic compounds and other physicochemical parameters in frozen mangoes were studied. Volatile and phenolic compounds were measured using SPME/GC‐MS and HPLC method, respectively. The results revealed that compared with untreated frozen mango, some volatile compounds (e.g. alcohols, aldehydes and some terpenes and esters) increased significantly and there were more compounds identified in osmo‐dehydrofrozen samples. These changes positively affected mango aroma and resulted in higher sensory scores for osmo‐dehydrofrozen samples. In addition, data on phenolic compounds showed that dehydrofrozen samples pretreated in glucose and sucrose had higher ρ‐hydroxybenzoic acid and quercetin contents, respectively, while samples pretreated in maltose showed higher ρ‐coumaric acid and sinapic acid contents compared with untreated frozen samples. The current work indicates that osmo‐dehydrofreezing can improve the retention of phenolic and aromatic compounds in frozen mango. 相似文献
999.
针对Web安全协议SSL的握手协议部分进行了详尽的阐述,对其安全性作了一定的分析,给出了理论上存在的三个协议漏洞的详尽描述,并且经过测试验证,指出了SSL协议存在***模式漏洞。 相似文献
1000.