Road construction in Africa is faced with a shortage of quality materials, leading to delays and increased costs. Traditional materials, such as clay soils of the bar soil type, have inadequate properties for pavement...Road construction in Africa is faced with a shortage of quality materials, leading to delays and increased costs. Traditional materials, such as clay soils of the bar soil type, have inadequate properties for pavement sub-base layers, particularly in terms of bearing capacity. This study explores a composite material combining bar soil and bamboo fibers to improve the mechanical performance of bar soil, offering a sustainable and cost-effective solution. The Tori-Bossito bar soil was characterised by particle size analysis, Atterberg limits, Proctor compaction tests and the California Bearing Ratio (CBR). The results show that this material is a class A2 sandy-clay soil with a CBR of 18, which is insufficient for foundation layers requiring a CBR of over 30. To improve its performance, Sèmè-Kpodji bamboo fibers, 30 to 100 microns in diameter and 3 to 5 cm long, were incorporated at rates of 0.9% to 2.7%. The optimum mix, with 2.4% fiber, has a CBR of 35, a dry density of 1.92 t/m3 and a moisture content of 12.4%. This reinforced material is suitable as a base course for low-traffic roadways.展开更多
火箭基组合循环(Rocket Based Combined Cycle,RBCC)推进系统是极具发展前景的组合动力方案,而模态转换阶段是RBCC发动机工作的关键环节,关系到整个推进系统的成败和效率。RBCC发动机的不同工作模态具有显著的分类特征,重点总结了引射/...火箭基组合循环(Rocket Based Combined Cycle,RBCC)推进系统是极具发展前景的组合动力方案,而模态转换阶段是RBCC发动机工作的关键环节,关系到整个推进系统的成败和效率。RBCC发动机的不同工作模态具有显著的分类特征,重点总结了引射/亚燃与亚燃/超燃两个关键转换阶段,综述相关特性与机理的研究进展,汇总实验与数值模拟方面的研究成果。与双模态超燃冲压发动机相比,RBCC发动机由于内含火箭射流,在模态平稳转换控制上具备优势。结合以等离子体为代表的新型多场燃烧耦合控制方式,RBCC发动机成为了当前超声速燃烧流动控制的研究热点。在总结相关进展的基础上,对未来的模态过渡研究提出了建议。展开更多
文摘Road construction in Africa is faced with a shortage of quality materials, leading to delays and increased costs. Traditional materials, such as clay soils of the bar soil type, have inadequate properties for pavement sub-base layers, particularly in terms of bearing capacity. This study explores a composite material combining bar soil and bamboo fibers to improve the mechanical performance of bar soil, offering a sustainable and cost-effective solution. The Tori-Bossito bar soil was characterised by particle size analysis, Atterberg limits, Proctor compaction tests and the California Bearing Ratio (CBR). The results show that this material is a class A2 sandy-clay soil with a CBR of 18, which is insufficient for foundation layers requiring a CBR of over 30. To improve its performance, Sèmè-Kpodji bamboo fibers, 30 to 100 microns in diameter and 3 to 5 cm long, were incorporated at rates of 0.9% to 2.7%. The optimum mix, with 2.4% fiber, has a CBR of 35, a dry density of 1.92 t/m3 and a moisture content of 12.4%. This reinforced material is suitable as a base course for low-traffic roadways.
文摘火箭基组合循环(Rocket Based Combined Cycle,RBCC)推进系统是极具发展前景的组合动力方案,而模态转换阶段是RBCC发动机工作的关键环节,关系到整个推进系统的成败和效率。RBCC发动机的不同工作模态具有显著的分类特征,重点总结了引射/亚燃与亚燃/超燃两个关键转换阶段,综述相关特性与机理的研究进展,汇总实验与数值模拟方面的研究成果。与双模态超燃冲压发动机相比,RBCC发动机由于内含火箭射流,在模态平稳转换控制上具备优势。结合以等离子体为代表的新型多场燃烧耦合控制方式,RBCC发动机成为了当前超声速燃烧流动控制的研究热点。在总结相关进展的基础上,对未来的模态过渡研究提出了建议。
