Longitudinal and transverse structure functions in decaying nearly homogeneous and isotropic turbulenceLongitudinal and transverse structure functions in decaying nearly homogeneous and isotropic turbulenceLongitudinal and transverse structure functions in decaying nearly homogeneous and isotropic turbulence

Streamwise evolution of longitudinal and transverse velocity structure functions in a decaying homogeneous and nearly isotropic turbulence is reported for Reynolds numbers Re;t up to 720. First, two theoretical relations between longitudinal and transverse structure functions are examined in the light of recently derived relations and the results show that the low-order transverse structure functions can be well approximated by longitudinal ones within the sub-inertial range. Reconstruction of fourth-order transverse structure functions with a recently proposed relation by Grauer et al. is comparatively less valid than the relation already proposed by Antonia et al. Secondly, extended self-similarity methods are used to measure the scaling exponents up to order eight and the streamwise evolution of scaling exponents is explored. The scaling exponents of longitudinal structure functions are, at first location, close to Zybin＇s model, and at the fourth location, close to She-Leveque model. No obvious wend is found for the streamwise evolution of longitudinal scaling exponents, whereas, on the contrary, transverse scaling exponents become slightly smaller with the development of a steamwise direction. Finally, the stremwise variation of the order-dependent isotropy ratio indicates the turbulence at the last location is closer to isotropic than the other three locations.     

Effects of acetone-soaking treatment on the performance of polymer solar cells based on P3HT/PCBM bulk heterojunction

The improvement of the acetone-soaking treatment to the performance of polymer solar cells based on the P3HT/PCBM bulk heterojunction is reported. Undergoing acetone-soaking, the PCBM does not distribute uniformly in the vertical direction, a PCBM enrichment layer forms on the top of the active layer, which is beneficial to the collec- tion of the carriers and blocking the inverting diffusion carriers. X-ray photoelectron spectroscopy （XPS） analysis reveals that the PCBM weight ratio on the top of the active layer increases by 20% after the acetone-soaking treatment. Due to the nonuniform distribution of PCBM, the short-circuit current density, the open-circuit voltage, and the fill factor are enhanced significantly. Finally, the power conversion efficiency of the acetone-soaking device increases by 31% compared with the control device.     

复合封装结构的微型X射线源

描述了一种用于便携式Ｘ射线图像增强透视装置的Ｘ射线源。该射线源采用了液体和固化的绝缘材料，以复合灌奎的结构形式装配组件，能在较小的体积，良好的机构性和低输入电压要求下，稳定地提供较高的恒管电压和管电流，及其状态下的Ｘ射线，射线源组件对漏射线的屏蔽效果符合国家相应标准的要求。     

高压绝缘材料在便携式X射线像增强仪中的应用

描述便携式Ｘ射线图像增强透视装置中应用的几种高压绝缘材料和它们的实施工艺，以及实施后的电性能结果。     

On the Mechanism of Turbulent Coherent Structure(Ⅰ)──The Physical Model o

ＯＮＴＨＥＭＥＣＨＡＮＩＳＭＯＦＴＵＲＢＵＬＥＮＴＣＯＨＥＲＥＮＴＳＴＲＵＣＴＵＲＥ（Ｉ）──ＴＨＥＰＹＳＩＣＡＬＭＯＤＥＬＯＦＴＨＥＣＯＨＥＲＥＮＴＳＴＲＵＣＴＵＲＥＦＯＲＴＨＥＳＭＯＯＴＨＢＯＵＮＤＡＲＹＬＡＹＥＲＴｓａｉｓｈｕ－ｔａｎｇ（蔡树棠...     

抚顺地区大气总悬浮微粒元素浓度季节变化的研究

本文采用X射线荧光法对抚顺地区大气总悬浮微粒（TSP）中S等20种元素的浓度水平进行分析，并通过无素的富集因子分析探讨TSP元素富集特征和污染来源，结果表明：采用暖期TSP浓度水平明显超过国家三级标准，其中富集程度较高的S，As,Zn等主要来源于煤炭燃烧。     

航天发射超导磁浮平台设计的初步实验研究

鉴于未来航天发射安全、可靠、低成本的要求,国外先后提出了不同磁悬浮系统助推发射运载器的概念及方案.我们基于初步拟定的高温超导磁悬浮发射系统方案,展开了相应的研究和探索.本文从磁浮系统悬浮力和稳定性综合考虑出发,建立配套高温超导实验测试系统,研究和比较了NdFeB永磁轨道构型和高温超导块材组合对磁浮系统性能的影响,并进行了定性的分析,其结果对小型缩比磁悬浮发射试验平台的构造具有极其重要的现实意义.     

A Simple Configuration for Discontinuous Wavelength-tuning Optical Pulse Source

A simple configuration is proposed to perform wavelength switching in actively mode-locked fiber ring lasers, in which a sampled fiber Bragg grating and a tunable optical filter are cascaded in the ring cavity to exactly select the operating wavelength. The switching of four wavelengths with a spacing of 1.6 nm is obtained. The experimental results demonstrate that this technique is reliable and convenient.     

A Simple Configuration for Discontinuous Wavelength-tuning Optical Pulse Source

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｗａｖｅｌｅｎｇｔｈ ｔｕｎａｂｌｅｕｌｔｒａ ｓｈｏｒｔｏｐｔｉｃａｌｐｕｌｓｅｓｏｕｒｃｅｓａｒｅａｔｔｒａｃｔｉｎｇｇｒｅａｔｉｎｔｅｒｅｓｔｆｏｒａｖａｒｉｅｔｙｏｆａｐｐｌｉｃａｔｉｏｎｓ,ｓｕｃｈａｓｏｐｔｉｃａｌｆｉｂｅｒｓｅｎｓｏｒｓ,ｗａｖｅｌｅｎｇｔｈ ｄｉｖｉｓｉｏｎｍｕｌｔｉｐｌｅｘｉｎｇｃｏｍｍｕｎｉｃａｔｉｏｎｓｙｓｔｅｍａｎｄｔｉｍｅ ｒｅｓｏｌｖｅｄｓｐｅｃｔｒｏｓｃｏｐｙ .Ｉｎｇｅｎｅｒａｌ,ｗａｖｅｌｅｎｇｔｈｔｕｎｉｎｇｉｓｒｅａｌｉ…     

形状记忆磁性润滑表面的制备及对超顺磁液滴的滑动操控

将磁性粒子与形状记忆聚合物复合,通过设计渐变式构型构筑了梯度形状磁性材料,并与润滑涂层相结合,制备了一种磁性润滑表面.在磁性梯度的作用下,超顺磁液滴在表面上能够自发定向运动.借助于材料形状记忆效应对表面区域形态进行可逆调控,进一步展示了超顺磁液滴自发定向运动过程中的启停开关式控制,实现了将液滴定向自发运输与启停控制相结合.考察了磁性粒子含量对材料形状记忆性能的影响,以及区域形态调控尺寸与液滴滑动性能间的相互关系.机理分析进一步阐明磁场梯度提供的定向驱动力促使液滴定向自发输运,表面区域形态控制的可逆调控则可以在液滴运动过程中增加/消除黏滞阻力,基于两种因素的协同作用,可以实现对超顺磁液滴运动的智能操控.