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631.
对10个新、老大豆品种冠层产量和光合作用的研究表明,新品种的产量显著高于老品种(P<0.01),新品种产量主要集中在冠层的中上部,而老品种的产量则以冠层中部最大,冠层上部、下部产量较低且相差不大.新品种植株叶面积和叶面积指数高于老品种,但差异不显著.新品种叶片的光合速率高于老品种,同时,新品种冠层不同部位叶片光合速率差异较小,老品种冠层不同部位叶片光合差异较大,特别是下层叶片净光合速率下降较大;由于新品种的叶面积指数和单位叶面积的净光合速率高于老品种,新品种的光合能力显著高于老品种,特别是冠层下部的光合能力得到了显著改善. 相似文献
632.
《中国航空学报》2023,36(1):434-443
Ultrasonic testing is effective in defect characterization and quality assurance of Carbon Fiber Reinforced Plastic (CFRP) components in the aerospace industry. Due to the coupling between complex shape and elastic anisotropy, the Phased Array Ultrasonic Testing (PAUT) and time-based Total Focusing Method (TFM) face significant challenges in the calculation of wave propagation. A wave velocity distribution model is established for a multidirectional convex corner of CFRP based on a homogenization theory and the above coupling effects are also incorporated. A ray-tracing method is proposed based on Dijkstra’s shortest path search algorithm. The predicted time of flight ensures that this technique, the homogenized TFM, could synthesize a high-quality focused image by post-processing on the full matrix capture data. Experiments on a laminate with three ?1.5 mm Side-Drilled Holes (SDHs) in different circumferential directions confirm a successful homogenized TFM imaging that all SDHs can be effectively detected. As compared to the isotropic scenario, the maximum positioning error is reduced to 0.12, 0.08, and 0.38 mm, and the Signal-to-Noise Ratios (SNRs) are increased by 2.1, 1.1, and 11.8 dB, respectively. It is suggested that the ray-tracing assisted TFM technique can effectively improve the imaging of corners in CFRP components. 相似文献
633.
Mingzheng LIU Changhe LI Yanbin ZHANG Min YANG Teng GAO Xin CUI Xiaoming WANG Wenhao XU Zongming ZHOU Bo LIU Zafar SAID Runze LI Shubham SHARMA 《中国航空学报》2023,36(7):160-193
Too high grinding force will lead to a large increase in specific grinding energy, resulting in high temperature in grinding zone, especially for the aerospace difficult cutting metal materials,seriously affecting the surface quality and accuracy. At present, the theoretical models of grinding force are mostly based on the assumption of uniform or simplified morphological characteristics of grains, which is inconsistent with the actual grains. Especially for non-engineering grinding wheel,most g... 相似文献
634.
To promote the development of fretting fatigue assessment and control technology for aircraft components, this paper uses the Crystal Plasticity Finite Element(CPFE) method and sub-modeling technology to study the Crack Initiation Location(CIL) of fretting fatigue in Aluminum Alloy(AA) specimens. The effects of external excitations such as normal load, tangential load, and axial stress on the CIL are investigated. It is found that the Most Likely Cracked(MLC) site revealed in a specimen and the ... 相似文献
635.
636.
Front Variable Area Bypass Injector(Front-VABI) is a component of the Adaptive Cycle Engine(ACE) with important variable-cycle features. The performance of Front-VABI has a direct impact on the performance and stability of ACE, but the current ACE performance model uses approximate models for Front-VABI performance calculation. In this work, a multi-fidelity simulation based on a de-coupled method is developed which delivers a more accurate calculation of the Front-VABI performance based on Comp... 相似文献
637.
在最佳设计面积比的情况下,整体壁板的设计可以得到较高的结构承载能力,但是对于整体壁板,蒙皮与筋条分离面的确定给实际设计工作造成很大障碍。本文针对这一问题开展了相关的研究工作,对蒙皮厚度在2.5mm~3.5mm范围内的“T”形整体壁板,在截面面积相同的条件下给定分离面位置,以最大失稳载荷为设计目标,得到蒙皮与筋条的最佳设计面积比。以此面积比设计的厚蒙皮“T”形整体壁板其承受轴压载荷的能力最强。 相似文献