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In this paper,the morphology and distribution of reduced metal prod-ucts on activated carbon fibers (ACFs) are investigated by means of SEMand the accessory of x-ray energy analyzer on SEM.The experimentalresults show that when metal ions are reduced by ACF into metal,thereduced product crystalizes out on the surface of ACF in the form of smallround granules by the inducement of crystal centers of ACF.As the granulesgrow up to stick to one another,a sieve-like crystal layer with manysmall holes dotted about... In this paper,the morphology and distribution of reduced metal prod-ucts on activated carbon fibers (ACFs) are investigated by means of SEMand the accessory of x-ray energy analyzer on SEM.The experimentalresults show that when metal ions are reduced by ACF into metal,thereduced product crystalizes out on the surface of ACF in the form of smallround granules by the inducement of crystal centers of ACF.As the granulesgrow up to stick to one another,a sieve-like crystal layer with manysmall holes dotted about is formed.The experimental results also indicatedthat many small holes range from 0.05 to 0.1μm are formed on ACF afterredox reaction.On the cross section of ACF,the metal atom can be foundeverywhere.From this,it is supposed that the micropores of ACF looklike“the paths in the cave of ant”and spread all over the ACF.It canbe described as the micropore network.The micropores of ACF are alwaysopening during redox reaction. 本工作采用扫描电子显微镜和扫描电镜上的X 射线能量谱仪附件对不同还原产物在各种ACF 表面的形态、ACF 的形貌以及还原产物在ACF 径向的分布进行研究,其结果不仅有助于对ACF 结构和氧化还原反应历程的认识,而且对于选择和控制应用工艺条件,以获得最佳的技术和经济效益也有一定指导意义。 A homomorphic signal processing method is presented for aecurate thickness measurement of thin layers.The method consists in taking the envelope of the inverse Fourier Transform of a corrected logarithnic derivative of the energy spectrum(ES) of the measured signal. Simulations show execllent agreement between estimated and actual values . 针对精确测量薄层厚度的要求,本文提出一种新的同态信号处理的方法,这种方法在于得出被测信号能量谱ES的对数导数的付里叶反变换的包络。仿真结果表明,估计值与实际值非常相近。 An analytical prediction method for helicopter rotor noise due to the ingestion of atmospheric turbulence is summarized.The method used here has accounted for the chordwise and spanwise noncompactness effects of blade surface pressure, and the blade-to-blade loading correlations. This method can be used to calculate absolute noise leyels for full scale helicopter in realistic flight conditions by incorporating an atmospheric turbulence model and a rapid distortion turbulence contraction model which together... An analytical prediction method for helicopter rotor noise due to the ingestion of atmospheric turbulence is summarized.The method used here has accounted for the chordwise and spanwise noncompactness effects of blade surface pressure, and the blade-to-blade loading correlations. This method can be used to calculate absolute noise leyels for full scale helicopter in realistic flight conditions by incorporating an atmospheric turbulence model and a rapid distortion turbulence contraction model which together determine the statistics of the non-isotropic and non-homogeneous turbulence at the rotor plan. The predicted turbulence ingestion noise levels are compared with the model rotor experimental results of a reference, and a good agreement is obtained. The distortion of turbulence field and the resulting noise spectra are calculated for six flight conditions of a helicopter, and it is found:(1)the distortions of turbulence for pseudo-hover case and low speed vertical ascent case are more severe ;(2) there is little distortion in the middle forward flight easel (3) in the low speed vertical ascent case, the overall SPL is the lowest. 本文简述了一种直升机旋翼与大气湍流入流相干扰产生的噪声预估方法。这一方法考虑了桨叶上非定常载荷的弦向及展向非紧致性,桨叶-桨叶载荷之间的相关,通过结合大气湍流能量谱模型与快速畸变湍流收缩模型来确定旋翼平面处非均匀、各向异性湍流场的特性,使得这种方法可用于直升机在真实飞行状态下的旋翼与湍流场干扰噪声计算。利用文献中模型旋翼试验的结果,验证了本方法的可行性,并计算了某型直升机在六种飞行状态下的流场畸变情况及旋翼与湍流干扰的远场噪声谱,结果表明:在准悬停及低速爬升状态,湍流场的畸变较大,而在中、快速前飞状态,湍流场的畸变最小,在低速爬升状态,线性总声压级最小。
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