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排序方式: 共有292条查询结果,搜索用时 31 毫秒
81.
王涛 《中国人民武装警察部队学院学报》2004,20(1):37-39
介绍我国建筑材料燃烧性能分级的现状和未来的发展方向,提出引进欧盟的分级体系形成新的分级方法,并进行分析比较。 相似文献
82.
离散变速趋近律抖振机理及鲁棒性研究 总被引:5,自引:1,他引:4
研究基于离散变速趋近律的变结构控制设计问题.利用不等式形式到达条件研究变速趋近律的抖振机理,并对其鲁棒性进行分析.研究结果表明,只要不确定因素有界,即可保证闭环系统的鲁棒稳定性,而通过调整变速趋近律自身参数,可以避免抖振并使系统具有良好的动态品质.将理论成果用于某型船舶航向自动舵的设计,实验结果证实了它的有效性. 相似文献
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针对航空装备体系构成复杂的特点,将故障树分析引入航空装备体系结构贡献率评估问题,提出基于故障树分析的评估方法。从作战装备、信息支援装备和保障装备三个方面构建航空装备体系结构,建造航空装备体系结构故障树;采用底事件的关键重要度指标来计算航空装备的体系结构贡献率,建立基于关键重要度的航空装备体系结构贡献率评估模型;以某航空装备体系为例进行建模分析。分析结果表明:所提方法能够准确评估航空装备体系结构贡献率,为确定航空装备体系结构短板、优化航空装备体系结构等提供方法支撑。 相似文献
86.
Ammonium nitrate and fuel oil (ANFO) based explosive is a classic example of non-ideal high explosives. Its detonation is characterized by a strong dependence of detonation parameters on explosive charge diameter, presence and characteristics of confinement, as well as incomplete consumption of explosive at the sonic point.In this work we propose a detonation model based on the Wood-Kirkwood (WK) theory coupled with the thermochemical code EXPLO5 and supplemented with reaction rate models. Our objective is to analyze the validity of the model for highly non-ideal ANFO explosives, with emphasis on effect of reaction rate models.It was found that both single-step and two-step pressure-based models can be calibrated to reproduce experimental detonation velocity-charge radius data of ANFO at radii significantly above the failure radius (i.e. for D/Did > ∼0.6). Single-step pressure-based model, with the pressure exponent equal to 1.4, proved to be the most accurate, even in the vicinity of the failure radius. The impact of the rate models is most evident on temporal (and spatial) distribution of flow parameters in detonation driving zone, especially when it comes to the conversion and width of detonation driving zone. 相似文献
87.
The photostabilies of hexanitrostillbene(HNS)were studied at 1%wt.of photostabilizers.The photo-stabilizers of Chiguard BP-12(UV-531),ADK STAB LA-326(UV-326),ADK STAB LA-32(UV-P),Irganox 1010 and Everstab LS944 were used in this study.A photoreactor including a 30 W monochromatic UV lamp was used for investigation of photodegradations of solid HNS.The changes in surface area of HNS peak in HPLC chromatogram at time intervals of 2,4,6 and 8 h were used for calculation of kinetic rate constants of photodegradation process.The compound of UV-P photostabilizer was found to have the greatest effect on enhancing photostability for HNS among the investigated photostabilizers.The kinetic rate constants were obtained 6.2 × 10-2 and 4.1 × 10-2 h-1,respectively,for photodegradation process of HNS in absence and in presence of UV-P. 相似文献
88.
Nano-sized aluminum(Nano-Al)powders hold promise in enhancing the total energy of explosives and the metal acceleration ability at the same time.However,the near-detonation zone effects of reaction between Nano-Al with detonation products remain unclear.In this study,the overall reaction process of 170 nm Al with RDX explosive and its effect on detonation characteristics,detonation reaction zone,and the metal acceleration ability were comprehensively investigated through a variety of experiments such as the detonation velocity test,detonation pressure test,explosive/window interface velocity test and confined plate push test using high-resolution laser interferometry.Lithium fluoride(LiF),which has an inert behavior during the explosion,was used as a control to compare the contribution of the reaction of aluminum.A thermochemical approach that took into account the reactivity of aluminum and ensuing detonation products was adopted to calculate the additional energy release by afterburn.Combining the numerical simulations based on the calculated afterburn energy and experimental results,the param-eters in the detonation equation of state describing the Nano-Al reaction characteristics were calibrated.This study found that when the 170 nm Al content is from 0%to 15%,every 5%increase of aluminum resulted in about a 1.3%decrease in detonation velocity.Manganin pressure gauge measurement showed no significant enhancement in detonation pressure.The detonation reaction time and reaction zone length of RDX/Al/wax/80/15/5 explosive is 64 ns and 0.47 mm,which is respectively 14%and 8%higher than that of RDX/wax/95/5 explosive(57 ns and 0.39 mm).Explosive/window interface velocity curves show that 170 nm Al mainly reacted with the RDX detonation products after the detonation front.For the recording time of about 10 μs throughout the plate push test duration,the maximum plate velocity and plate acceleration time accelerated by RDX/Al/wax/80/15/5 explosive is 12%and 2.9 μs higher than that of RDX/LiF/wax/80/15/5,respectively,indicating that the aluminum reaction energy significantly increased the metal acceleration time and ability of the explosive.Numerical simulations with JWLM explosive equation of state show that when the detonation products expanded to 2 times the initial volume,over 80%of the aluminum had reacted,implying very high reactivity.These results are significant in attaining a clear understanding of the reaction mechanism of Nano-Al in the development of aluminized explosives. 相似文献
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Qiang Liu Peng-wan Chen Yan-song Guo Jian-jun Su Lu Han Ali Arab Jian-fei Yuan 《防务技术》2021,17(2):495-504
Polyurea is an elastomeric material that can be applied to enhance the protection ability of structures under blast and impact loading.In order to study the compressive mechanical properties of SiC/polyurea nanocomposites under quasi-static and dynamic loading,a universal testing machine and split Hop-kinson pressure bar(SHPB)apparatus were used respectively.The stress-strain curves were obtained on polyurea and its composites at strain rates of 0.001-8000 s-1.The results of the experiment suggested that increase in the strain rates led to the rise of the flow stress,compressive strength,strain rate sensitivity and strain energy.This indicates that all of the presented materials were dependent on strain rate.Moreover,these mechanical characters were enhanced by incorporating a small amount of SiC into polyurea matrix.The relation between yield stress and strain rates were established using the power law functions.Finally,in order to investigate the fracture surfaces and inside information of failed specimens,scanning electron microscopy(SEM)and micro X-ray computed tomography(micro-CT)were used respectively.Multiple voids,crazes,micro-cracks and cracking were observed in fracture surfaces.On the other hand,the cracking propagation was found in the micro-CT slice images.It is essential to understand the deformation and failure mechanisms in all the polyurea materials. 相似文献