为综合优化离心泵作透平的水力和声学性能,建立了一种基于响应面的离心泵作透平水力和声学性能多目标优化方法。首先在对比分析叶轮几何参数对透平水力和噪声影响的基础上,根据敏感度筛选出对噪声影响显著的关键参数;进而应用响应面方...为综合优化离心泵作透平的水力和声学性能,建立了一种基于响应面的离心泵作透平水力和声学性能多目标优化方法。首先在对比分析叶轮几何参数对透平水力和噪声影响的基础上,根据敏感度筛选出对噪声影响显著的关键参数;进而应用响应面方法构造显著变量与多目标函数的响应面多元回归模型,分析影响水力效率与噪声的参数间交互作用;最终以水力效率不降低和总声压级最小为响应目标,兼顾性能与噪声确定最优参数组合,即叶片进口安放角为19.5°,叶片出口安放角为20°,叶片出口宽度为16 mm,叶片包角为92°,叶轮进口直径为101 mm,叶片数为12。对某离心泵作透平多目标优化结果表明,叶轮进口直径、叶片出口宽度、叶片数及叶片包角对内场噪声总声压级影响显著;响应面模型能够反映参数与响应值之间的相关性;经试验验证优化后透平水力效率平均提高了1.98个百分点,总声压级降低了4.95 d BA,表明采用的响应面法能够在不影响透平原有水力性能的前提下改善声学性能。展开更多
With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided m...With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.展开更多
Applications of optical switches,such as signal routing and data-intensive computing,are critical in optical interconnects and optical computing.Integrated optical switches enabled by two-dimensional(2D)materials and ...Applications of optical switches,such as signal routing and data-intensive computing,are critical in optical interconnects and optical computing.Integrated optical switches enabled by two-dimensional(2D)materials and beyond,such as graphene and black phosphorus,have demonstrated many advantages in terms of speed and energy consumption compared to their conventional silicon-based counterparts.Here we review the state-of-the-art of optical switches enabled by 2D materials and beyond and organize them into several tables.The performance tables and future projections show the frontiers of optical switches fabricated from 2D materials and beyond,providing researchers with an overview of this field and enabling them to identify existing challenges and predict promising research directions.展开更多
文摘为综合优化离心泵作透平的水力和声学性能,建立了一种基于响应面的离心泵作透平水力和声学性能多目标优化方法。首先在对比分析叶轮几何参数对透平水力和噪声影响的基础上,根据敏感度筛选出对噪声影响显著的关键参数;进而应用响应面方法构造显著变量与多目标函数的响应面多元回归模型,分析影响水力效率与噪声的参数间交互作用;最终以水力效率不降低和总声压级最小为响应目标,兼顾性能与噪声确定最优参数组合,即叶片进口安放角为19.5°,叶片出口安放角为20°,叶片出口宽度为16 mm,叶片包角为92°,叶轮进口直径为101 mm,叶片数为12。对某离心泵作透平多目标优化结果表明,叶轮进口直径、叶片出口宽度、叶片数及叶片包角对内场噪声总声压级影响显著;响应面模型能够反映参数与响应值之间的相关性;经试验验证优化后透平水力效率平均提高了1.98个百分点,总声压级降低了4.95 d BA,表明采用的响应面法能够在不影响透平原有水力性能的前提下改善声学性能。
基金the Indian Institute of Technology Bombay’s Post-Doctoral Research Program, vide appointment no. AO/Admn1/33/2018 dated 10.Aug’2018 for providing funding
文摘With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.
基金supported in part by the National Key Research and Development Project of China(No.2018YFB2201901)in part by the National Natural Science Foundation of China(Grant No.61805090).
文摘Applications of optical switches,such as signal routing and data-intensive computing,are critical in optical interconnects and optical computing.Integrated optical switches enabled by two-dimensional(2D)materials and beyond,such as graphene and black phosphorus,have demonstrated many advantages in terms of speed and energy consumption compared to their conventional silicon-based counterparts.Here we review the state-of-the-art of optical switches enabled by 2D materials and beyond and organize them into several tables.The performance tables and future projections show the frontiers of optical switches fabricated from 2D materials and beyond,providing researchers with an overview of this field and enabling them to identify existing challenges and predict promising research directions.
