616 resultados para yuan
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
The present paper describes a systematic study of argon plasmas in a bell-jar inductively coupled plasma (ICP) source over the range of pressure 5-20 mtorr and power input 0.2-0.5 kW, Experimental measurements as well as results of numerical simulations are presented. The models used in the study include the well-known global balance model (or the global model) as well as a detailed two-dimensional (2-D) fluid model of the system, The global model is able to provide reasonably accurate values for the global electron temperature and plasma density, The 2-D model provides spatial distributions of various plasma parameters that make it possible to compare with data measured in the experiments, The experimental measurements were obtained using a tuned Langmuir double-probe technique to reduce the RF interference and obtain the light versus current (I-V) characteristics of the probe. Time-averaged electron temperature and plasma density were measured for various combinations of pressure and applied RF power, The predictions of the 2-D model were found to be in good qualitative agreement with measured data, It was found that the electron temperature distribution T-e was more or less uniform in the chamber, It was also seen that the electron temperature depends primarily on pressure, but is almost independent of the power input, except in the very low-pressure regime. The plasma density goes up almost linearly with the power input.
Resumo:
This paper describes the experimental and theoretical studies of gas-liquid bubbly flow in vertical upward pipeline carried out at Institute of Mechanics, Chinese Academy of Sciences. Bubbly flow in a vertical pipe with a 3 m long and 5 cm inner diameter plexiglass pipe was experimentally investigated, and studies carried out on the relationship between superficial velocities of the liquid and gas phases and pressure gradient is described. The developed drift-flux model applied to gas-liquid bubbly flow is presented, and the results are compared against the experimental data measured by ours in air/water vertical pipes.
Resumo:
目录
- 访罗湖 忆当年[李佩]
- 怀念同窗益友郭永怀教授[钱伟长]
- 郭永怀追求科学、为国献身的一生[洪友士]
- 深深怀念为核盾牌献身的著名科学家--郭永怀先生 中国工程物理研究院
- 深切怀念郭永怀教授的奠基性贡献 中国空气动力研究与发展中心
- 胸怀长江长城 心系国家安危--纪念我国核防护工程奠基人郭永怀先生[周丰峻]
- 缅怀我们的首任系主任--郭永怀教授[辛厚文 马兴孝 俞书勤 何天敬]
- 科学和技术结合的典范--纪念郭永怀先生诞辰九十周年[郑哲敏 李家春]
- 怀念与感激[俞鸿儒]
- 继承先师遗愿,谈我所冲击动力学的发展--纪念郭永怀副院长诞辰九十周年[陈裕泽]
- 英名长存--纪念郭永怀副院长诞辰九十周年[沈中毅]
- 郭永怀与我国导弹弹头再入气动物理研究[魏叔如]
- 科研工作引路人--纪念郭永怀九十诞辰[胡在军]
- 科技楷模,引路良师--怀念敬爱的郭永怀副院长[朱竟洪 郑百瑛]
- 七律 永怀永怀郭老师[董务民]
- 留得春晖映核魂--怀念我们的好领导好老师郭永怀同志[孙德纶 张克才]
- 难以忘怀--忆郭永怀副院长事迹点滴[孙天雄]
- 研究工作与工程技术工作之间的关系[谈庆明]
- 忆敬爱的郭永怀老师[张兆顺 呼和敖德]
- 根深叶茂 厚积薄发--追忆恩师郭永怀先生教诲我打好基础[严宗毅]
- 力学前辈,科德风范[徐友钜]
- 领导的楷模 学者的典范 青年的导师--怀念郭永怀副院长[于长勤]
- 怀念郭永怀副院长[陈裕泽]
- 关于郭永怀事迹的回顾[张长富]
- 严谨的导师,可亲的长者--忆著名的空气动力学家郭永怀先生[吴兰春]
- 严谨细致 实事求是--纪念郭永怀九十诞辰[李启廉]
- 纪念核武器环境试验技术的奠基人--郭永怀副院长诞辰九十周年[李荣林]
- 郭老精神激励着材料科学研究的不断深入[周维宣 谭云]
- 郭永怀副院长的关怀与我所有机材料研究的发展[陈晓丽]
- 忆与郭永怀副院长的一次谈话[孙德纶]
- 缅怀郭永怀院士[陈家镛]
- 记郭永怀先生二三事[屠善澄]
- Remembering Yunghuai Kuo[C.C.Lin]
- Recall with love and respect[William R.Sears]
- Y.H.Kuo:An appreciation[Frank E.Marble]
- A commemorative tribute to Professor Guo Yonghuai[T.Y.Wu]
- Y.H.Kuo:A great scientist,revered teacher and good friend[Alfred Ritter]
- 氢氧燃烧及爆轰驱动激波管[俞鸿儒]
- 颗粒材料中致密波结构研究[孙锦山 朱建士 贾祥瑞]
- 网格与高精度差分计算问题[张涵信 呙超 宗文刚]
- 植被层湍流的大涡模拟[李家春 谢正桐]
- 半浮区液桥热毛细振荡流[唐泽眉 阿燕 胡文瑞]
- 再入湍流尾迹及其对雷达散射的影响研究[牛家玉 于明]
- 超声射流中CS2分子态分辨转动弛豫研究[陈从香 刘世林 戴静华 张志萍 马兴孝]
- 37mm冲压加速器实验和计算[柳森 简和祥 白智勇 平新红 部绍清]
- 化学体系中噪声诱导的时空有序结构和随机共振[辛厚文 侯中怀 杨灵法]
- 根据守恒律计算热流和摩阻的有限元提法[童秉纲 段占元]
- 高阶精度线性耗散紧致格式的渐近稳定性[邓小刚 毛枚良]
- 离散流体力学:理论和数值方法[高智]
- 2号复合离心机自动控制系统研制[王磊 林明 冯晓军]
- 海沧大桥气动弹性特性风洞试验研究[李明水 陈忻 张大康 王卫华]
- 内爆炸载荷下圆管变形、损伤和破坏规律的研究[李永池 李大红 魏志刚 孙宇新]
- 两种凝聚炸药的静态断裂性能实验研究[罗景润 韦日演 马丽莲]
- 圆柱体侵彻薄靶极限击穿速度估算探讨[吴应白 唐平]
- 动力学修改方法在夹具设计中的应用研究[蒲怀强 唐定勇]
- Numerical simulation of non-linear stability of two-dimensional supersonic boundary layer[Shen Qing Yuan Xiangjiang]
Resumo:
Density functional theory/molecular dynamics simulations were employed to give insights into the mechanism of voltage generation based on a water-filled single-walled boron-nitrogen nanotube (SWBNNT). Our calculations showed that (1) the transport properties of confined water in a SWBNNT are different from those of bulk water in view of configuration the diffusion coefficient the dipole orientation and the density distribution and (2) a voltage difference of several millivolts would generate between the two ends of a SWBNNT due to interactions between the water dipole chains and charge carriers in the tube. Therefore this structure of a water-filled SWBNNT can be a promising candidate for a synthetic nanoscale power cell as well as a practical nanopower harvesting device.
Resumo:
For efficiently cooling electronic components with high heat flux, experiments were conducted to study the flow boiling heat transfer performance of FC-72 over square silicon chips with the dimensions of 10 × 10 × 0.5 mm3. Four kinds of micro-pin-fins with the dimensions of 30 × 60, 30 × 120, 50 × 60, 50 × 120 μm2 (thickness, t × height, h) were fabricated on the chip surfaces by the dry etching technique for enhancing boiling heat transfer. A smooth surface was also tested for comparison. The experiments were made at three different fluid velocities (0.5, 1 and 2 m/s) and three different liquid subcoolings (15, 25 and 35 K). The results were compared with the previous published data of pool boiling. All micro-pin-fined surfaces show a considerable heat transfer enhancement compared with a smooth surface. Flow boiling can remarkably decrease wall superheat compared with pool boiling. At the velocities lower than 1 m/s, the micro-pin-finned surfaces show a sharp increase in heat flux with increasing wall superheat. For all surfaces, the maximum allowable heat flux, qmax, for the normal operation of LSI chips increases with fluid velocity and subcooling. For all micro-pin-finned surfaces, the wall temperature at the critical heat flux (CHF) is less than the upper limit for the reliable operation of LSI chips, 85◦C. The largest value of qmax can reach nearly 148 W/cm2 for micro-pin-finned chips with the fin height of 120 μm at the fluid velocity of 2 m/s and the liquid subcooling of 35 K. The perspectives for the boiling heat transfer experiment of the prospective micro-pin-finned sur- faces, which has been planned to be made in the Drop Tower Beijing/NMLC in the future, are also presented.
Resumo:
We measured spectroscopic and laser action properties of a novel 8-position substituted pyrromethene-BF2, namely 1,3,5,7-tetramethyl-2,6-diethyl-8-n-propyl pyrromethene-BF2 complex. The laser action was performed with the corresponding dye solution in ethanol, which was placed in a Littman-type laser cavity pumped by the second harmonic of a Q-switched Nd:YAG laser. The spectroscopic measurements clearly indicated that the corresponding dye solution in ethanol exhibited intense absorption in the visible spectral region with large fluorescence quantum yield. It possesses rather low triplet-triplet absorption in the spectral region 460-550 nm and almost negligible triplet-triplet absorption in the lasing spectral region. As a consequence, it lases nearly as efficiently as commercially available benchmark laser dyes such as Rhodamine-6G and outperformed them in wavelength tunability in our laser cavity and pump geometry. (C) 2002 Optical Society of America.
Resumo:
For the purpose of human-computer interaction (HCI), a vision-based gesture segmentation approach is proposed. The technique essentially includes skin color detection and gesture segmentation. The skin color detection employs a skin-color artificial neural network (ANN). To merge and segment the region of interest, we propose a novel mountain algorithm. The details of the approach and experiment results are provided. The experimental segmentation accuracy is 96.25%. (C) 2003 Society of Photo-Optical Instrumentation Engineers.
Resumo:
The coherent anti-Stokes Raman scattering (CARS) microscope with the combination of confocal and CARS techniques is a remarkable alternative for imaging chemical or biological specimens that neither fluoresce nor tolerate labelling. CARS is a nonlinear optical process, the imaging properties of CARS microscopy will be very different from the conventional confocal microscope. In this paper, the intensity distribution and the polarization property of the optical field near the focus was calculated. By using the Green function, the precise analytic solution to the wave equation of a Hertzian dipole source was obtained. We found that the intensity distributions vary considerably with the different experimental configurations and the different specimen shapes. So the conventional description of microscope (e.g. the point spread function) will fail to describe the imaging properties of the CARS microscope.
Resumo:
A constrained high-order statistical algorithm is proposed to blindly deconvolute the measured spectral data and estimate the response function of the instruments simultaneously. In this algorithm, no prior-knowledge is necessary except a proper length of the unit-impulse response. This length can be easily set to be the width of the narrowest spectral line by observing the measured data. The feasibility of this method has been demonstrated experimentally by the measured Raman and absorption spectral data.
The intensity distributions of collected signals in coherent anti-Stokes Raman scattering microscopy
Resumo:
Coherent anti-Stokes Raman scattering (CARS) microscopy with the combining of confocal and CARS techniques is a remarkable alternative for imaging chemical or biological specimens that neither fluoresce nor tolerate labeling. The CARS is a nonlinear optical process, the imaging properties of CARS microscopy will be very different from the conventional confocal microscopy. In this paper, we calculated the propagation of CARS signals by using the wave equation in medium and the slowly varying envelope approximation (SVEA), and find that the intensity angular distributions vary considerably with the different experimental configurations and the different specimen shapes. So the conventional description of microscopy (e.g.. the point spread function) will fail to descript the imaging properties of CARS microscopy. (c) 2004 Elsevier B.V. All rights reserved.
Resumo:
Filamentation formed by self-focusing of intense laser pulses propagating in air is investigated. It is found that the position of filamentation can be controlled continuously by changing the laser power and divergence angle of the laser beam. An analytical model for the process is given.
Resumo:
This paper presents a funnel external potential model to investigate dynamic properties of ultracold Bose gas. By using variational method, we obtain the ground-state energy and density properties of ultracold Bose atoms. The results show that the ultracold Bose gas confined in a funnel potential experiences the transition from three-dimensional regime to quasi-one-dimensional regime in a small aspect ratio, and undergoes fermionization process as the aspect ratio increases.
Resumo:
In this paper, we propose a novel method for measuring the coma aberrations of lithographic projection optics based on relative image displacements at multiple illumination settings. The measurement accuracy of coma can be improved because the phase-shifting gratings are more sensitive to the aberrations than the binary gratings used in the TAMIS technique, and the impact of distortion on displacements of aerial image can be eliminated when the relative image displacements are measured. The PROLITH simulation results show that, the measurement accuracy of coma increases by more than 25% under conventional illumination, and the measurement accuracy of primary coma increases by more than 20% under annular illumination, compared with the TAMIS technique. (c) 2007 Optical Society of America.
Resumo:
The correlation between the coma sensitivity of the alternating phase-shifting mask (Alt-PSM) mark and the mark's structure is studied based on the Hopkins theory of partially coherent imaging and positive resist optical lithography (PROLITH) simulation. It is found that an optimized Alt-PSM mark with its phase width being two-thirds its pitch has a higher sensitivity to coma than Alt-PSM marks with the same pitch and the different phase widths. The pitch of the Alt-PSM mark is also optimized by PROLITH simulation, and the structure of p - 1.92 lambda/NA and pw = 2p/3 proves to be with the highest sensitivity. The optimized Alt-PSM mark is used as a measurement mark to retrieve coma aberration from the projection optics in lithographic tools. In comparison with an ordinary Alt-PSM mark with its phase width being a half its pitch, the measurement accuracies of Z(7) and Z(14) apparently increase. (C) 2009 Optical Society of America
Resumo:
In the present paper, we propose a novel method for measuring the even aberrations of lithographic projection optics by use of optimized phase-shifting marks on the test mask. The line/space ratio of the phase-shifting marks is optimized to obtain the maximum sensitivities of Zernike coefficients corresponding to even aberrations. Spherical aberration and astigmatism can be calculated from the focus shifts of phase-shifting gratings oriented at 0 degrees, 45 degrees, 90 degrees and 135 degrees at multiple illumination settings. The PROLITH simulation results show that, the measurement accuracy of spherical aberration and astigmatism obviously increase, after the optimization of the measurement mark. (C) 2008 Elsevier B.V. All rights reserved.