The gated integration technique for the accurate measurement of the autocorrelation function of speckle intensities scattered from random phase screens

A new approach based on the gated integration technique is proposed for the accurate measurement of the autocorrelation function of speckle intensities scattered from a random phase screen. The Boxcar used for this technique in the acquisition of the speckle intensity data integrates the photoelectric signal during its sampling gate open, and it repeats the sampling by a preset number, in. The average analog of the in samplings output by the Boxcar enhances the signal-to-noise ratio by root m, because the repeated sampling and the average make the useful speckle signals stable, while the randomly varied photoelectric noise is suppressed by 1/ root m. In the experiment, we use an analog-to-digital converter module to synchronize all the actions such as the stepped movement of the phase screen, the repeated sampling, the readout of the averaged output of the Boxcar, etc. The experimental results show that speckle signals are better recovered from contaminated signals, and the autocorrelation function with the secondary maximum is obtained, indicating that the accuracy of the measurement of the autocorrelation function is greatly improved by the gated integration technique. (C) 2006 Elsevier Ltd. All rights reserved.

Experimental Observation Of Electrical Instability Of Droplets On Dielectric Layer

Polydimethylsiloxane ( PDMS) has become the most widely used silicon-based organic polymer in bio-MEMS/NEMS devices. However, the inherent hydrophobic nature of PDMS hinders its wide applications in bio-MEMS/NEMS for efficient transport of liquids. Electrowetting is a useful tool to reduce the apparent contact angle of partially wetting conductive liquids and has been utilized widely in bio-MEMS/NEMS. Our experimental results show that the thin PDMS membranes exhibit good properties in electrowetting-on-dielectric. The electrical instability phenomenon of droplets was observed in our experiment. The sessile droplet lying on the PDMS membrane will lose its stability with the touch of the wire electrode to make the apparent contact angle change suddenly larger than 35 degrees. Contact mode can protect the dielectric layer from electrical breakdown effectively. Electrical breakdown process of dielectric layer was recorded by a high speed camera. It is found experimentally that a PDMS membrane of 4.8 mu m thick will not be destroyed due to the electric breakdown even at 800 V in the contact mode.

Statistical Interpolation Method of Turbulent Phase Screen

A relative displacement between the grid points of optical fields and those of phase screens may occur in the simulation of light propagation through the turbulent atmosphere. A statistical interpolator is proposed to solve this problem in this paper. It is evaluated by the phase structure function and numerical experiments of light propagation through atmospheric turbulence with/without adaptive optics (AO) and it is also compared with the well-known linear interpolator under the same condition. Results of the phase structure function show that the statistical interpolator is more accurate in comparison with the linear one, especially in the high frequency region. More importantly, the long-exposure results of light propagation through the turbulent atmosphere with/without AO also show that the statistical interpolator is more accurate and reliable than the linear one. (C) 2009 Optical Society of America.

Plane strain asymptotic fields for cracks terminating at the interface between elastic and pressure-sensitive dilatant materials

The plane strain asymptotic fields for cracks terminating at the interface between elastic and pressure-sensitive dilatant material are investigated in this paper. Applying the stress-strain relation for the pressure-sensitive dilatant material, we have obtained an exact asymptotic solution for the plane strain tip fields for two types of cracks, one of which lies in the pressure-sensitive dilatant material and the other in the elastic material and their tips touch both the bimaterial interface. In cases, numerical results show that the singularity and the angular variations of the fields obtained depend on the material hardening exponent n, the pressure sensitivity parameter mu and geometrical parameter lambda.

Jet:progress in performance and understanding

In 1990 JET operated with a number of technical improvements which led to advances in performance and permitted the carrying out of experiments specifically aimed at improving physics understanding of selected topics relevant to the "NEXT STEP". The new facilities include beryllium antenna screens, a prototype lower hybrid current drive system, and modification of the NI system to enable the injection of He-3 and He-4. Continued investigation of the hot-ion H-mode produced a value of n(D)(0)tau-E(T)(i)(0) = 9 x 10(20)m-3s keV, which is near conditions required for Q(DT) = 1, while a new peaked density profile H-mode was developed with only slightly lower performance. Progress towards steady state operation has been made by achieving ELMy H-modes under certain operating conditions, while maintaining good tau-E values. Experimental simulation of He ash transport indicates effective removal of alpha-particles from the plasma core for both L and H mode plasmas. Detailed analyses of particle and energy transport have helped establish a firmer link between particle and energy transport, and have suggested a connection between reduced energy transport and reversed shear. Numerical and analytic studies of divertor physics carried out for the pumped divertor phase of JET have helped clarify the key parameters governing impurity retention, and an intensive model validation effort has begun. Experimental simulation of alpha-particle effects with beta-fast up to 8% have shown that the slowing down processes are classical, and have given no evidence of deleterious collective effects.

Heating, current drive and confinement regimes with the JET ICRH and lhcd systems

During its 1990 operation, 2 large RF systems were available on JET. The Ion Cyclotron Resonance Heating (ICRH) system was equipped with new beryllium screens and with feedback matching systems. Specific impurities generated by ICRH were reduced to negligible levels even in the most stringent H-mode conditions. A maximum power of 22 MW was coupled to L-mode plasmas. High quality H-modes (tau-E greater-than-or-equal-to 2.5 tau-EG) were achieved using dipole phasing. A new high confinement mode was discovered. It combines the properties of the H-mode regime to the low central diffusivities obtained by pellet injection. A value of n(d) tau-E T(i) = 7.8 x 10(20) m-3 s keV was obtained in this mode with T(e) approximately T(i) approximately 11 keV. In the L-mode regime, a regime, a record (140 kW) D-He-3 fusion power was generated with 10 - 14 MW of ICRH at the He-3 cyclotron frequency. Experiments were performed with the prototype launcher of the Lower Hybrid Current Drive (LHCD) systems with coupled power up to 1.6 MW with current drive efficiencies up to < n(e) > R I(CD)/P = 0.4 x 10(20) m-2 A/W. Fast electrons are driven by LHCD to tail temperatures of 100 keV with a hollow radial profile. Paradoxically, LHCD induces central heating particularly in combination with ICRH. Finally we present the first observations of the synergistic acceleration of fast electrons by Transit Time Magnetic Pumping (TTMP) (from ICRH) and Electron Landau Damping (ELD) (from LHCD). The synergism generates TTMP current drive even without phasing the ICRH antennae.

基于畸变相位波前分形特征产生矩形湍流相屏

在包含时间进程的光波大气传输及其自适应光学相位校正的数值模拟研究中,如长曝光成像和自适应光学系统的动态控制过程,矩形湍流相屏的产生和应用尤为重要.而现在通常使用的功率谱反演法产生的是正方形的湍流相屏,只采用其中的矩形部分显然造成计算机资源的浪费;并且谱反演法产生的湍流相屏需要进行低频补偿,从而明显地增加计算量.基于大气湍流所造成的畸变相位波前的分形特征,提出了一种产生矩形湍流相屏的新方法,并与解析理论结果进行对比,验证了这种矩形相屏产生方法的正确性.与已有的方法相比,此算法具有两个明显的优点:算法简单、计算效率高,节省计算机资源;与大气湍流介质统计特性无论在高频部分还是在低频部分均符合得较好.

X 射线转换屏用Tb3+激活磷酸盐发光玻璃

Phosphate glasses 60P2O5-15CS2O- 15Al2O3-10BaO were made by high temperature melt-annealing method. The absorption spectra, excitation spectra and emission spectra of Gd³⁺-Tb³⁺ and Ce3+-Gd³⁺-Tb³⁺ co-doped phosphate glass 60P2O5-15CS2O- 15Al2O3-10BaO were studied. The experimental results indicate that, the doping of Ce3+ and Gd³⁺ in Tb³⁺ phosphate glass has a good effect on the 545 nm emission of Tb³⁺ at UV excitation. The Ce3+-Gd³⁺-Tb³⁺ co-doped phosphate glass have a good x-ray luminescence at the radiation of x-ray with energy in 50-120 kev, and a high space resolution. The Ce3+-Gd³⁺-Tb³⁺ co-doped phosphate luminescence glass is a promising material for using in the digital radiography system in medical devices.

显微成像荧光屏用无机闪烁单晶薄膜的研究进展

随着第三代同步辐射源的出现，由荧光屏和CCD耦合组成的、具有亚微米级空间分辨率、快速在线成像功能的探测器在医疗、安检、工业、科研等领域将会得到广泛应用．本文主要综述了成像荧光屏用材料的概况和发展趋势，重点阐述了闪烁单晶薄膜的研究及发展情况．

基于视觉的手势界面关键技术研究

针对视觉手势界面存在的问题,提出了一套行之有效的解决方案.首先,为了解决视觉手势交互中的Midas Touch问题,以人类注意的信息加工模型为理论依据提出了一个可扩展的视觉手势交互模型,该模型将手势交互过程分为选择性处理、分配性处理和集中处理3个不同阶段;然后,基于该模型提出了一个视觉手势识别框架,并结合认知心理学从手势检测、跟踪和识别3个方面对该框架的各个组成模块的关键技术进行了阐述,其中手势检测模块和识别管理模块能够辅助系统在复杂的背景中滤除掉不相关信息而选择性地搜索人手并根据上下文信息对手势识别任务重定向,从而避免了系统时刻都处于激活状态并对所有的手势动作都进行识别分析,有效解决了Midas Touch问题.文中介绍了使用该方法实现的IEToolkit手势界面工具平台,并基于一个视觉手势交互系统进行了实验测试与评估,结果验证了文中方法的可用性.

基于手势的视觉用户界面研究

随着人机交互技术的发展，各种新的交互手段不断涌现，使人机交互朝着更加自然、高效和智能化的方向前进。基于手势的视觉用户界面是post-WIMP时代的一种重要的界面形式，与传统的WIMP交互方式相比视觉手势交互能够使用户摆脱鼠标键盘的束缚而采用一种更加自然、无约束的交互方式，从而提供给用户更大的交互空间、更多的交互自由度和更逼真的交互体验，具有较高的应用价值和良好的应用前景，因此被国内外越来越多的研究者所关注，迅速成为了人机交互领域一个热门的研究方向，并被广泛应用于虚拟/增强现实、普适计算、智能空间以及基于计算机的互动游戏等多个领域。 视觉交互是自然人机交互的核心和热点研究内容之一，视觉交互可以通过手势、目光、头部运动或者面部表情等多种方式进行。其中，手势是人类进行视觉交互的主要手段，手势所能表达的语义信息十分丰富。在人机交互中使用视觉手势完成交互任务不仅自然、直观和方便，而且从计算机的角度出发来看系统实现起来也较为容易。因此，基于手势的视觉用户界面得到了广泛的关注并取得了许多研究成果。从目前的研究现状来看，在基于手势的视觉用户界面研究中，仍然存在着以下的问题： （1）传统的WIMP界面模型已经不适合描述视觉手势界面这种post-WIMP界面的特点，需要对传统的用户界面模型加以扩展，构造适于描述视觉交互特征的界面模型帮助用户清晰、准确地分析和表达界面功能及其变化，描述出用户与系统的交互过程，指导软件系统的设计和实现； （2）具体的交互设计过程中还存在着许多关键技术没有解决好，例如手势的正确理解问题、算法的鲁棒性问题以及手势的可扩展性问题等； （3）传统视觉工具箱复杂难用的问题。需要降低开发难度，开发出便捷、易用、可扩展的软件界面开发工具及相应的开发方法，支持领域内非专家用户快速开发出视觉手势原型系统。 本文正是从以上问题出发，围绕着视觉手势界面交互技术，从理论、方法与应用等几个方面展开了深入的研究。首先论述了用户界面的发展历程，继而对视觉界面研究现状进行了综述。在充分研究和对比国内外相关研究成果的基础上提出了一种基于手势的视觉用户界面模型UIDT。接下来针对视觉手势交互中存在的难题，以认知心理学为理论依据提出了一种可扩展的手势交互状态转移模型，并在此基础上构建了视觉手势处理框架。随后对该框架中的关键技术进行了针对性的研究。针对非专家用户在构建具有个性化视觉手势界面过程中所遇到的问题，设计开发了一个支持视觉手势交互的开发工具IEToolkit并给出了一套基于该工具的通用的软件开发方法。最后，将上述成果应用于互动娱乐领域，取得了满意的效果。 本文的创新点主要表现在以下几个方面： 1. 提出了一种基于手势的视觉用户界面模型UIDT 在充分分析视觉交互特征的基础上，以传统的用户界面模型为基础提出了一种基于手势交互的视觉界面模型UIDT。该模型从用户模型、任务模型、设备模型和交互模型等几个方面对视觉手势交互进行了深入分析和描述，给出了各个模型的形式化定义，介绍了模型的各个组成模块以及它们之间的相互关系，讨论了视觉手势界面设计中应该遵循的设计规范。评估结果表明，该模型具有较强的通用性，有助于设计者对VBI的任务、用户、设备以及交互的不同层次进行抽象描述，使用户界面满足可用性要求，提高界面设计和原型开发的效率。 2. 提出了一个可扩展的视觉手势交互模型及一种新的视觉手势识别处理框架，围绕着该框架提出了一种新的视觉手势跟踪和识别方法 首先，提出了一个可扩展的视觉手势交互模型。根据认知心理学原理将视觉手势交互处理过程细分为选择性处理、分配性处理和集中处理三个不同的阶段，有效解决了Midas Touch问题；基于该模型提出了一个视觉手势识别框架，并结合认知心理学从手势检测、跟踪和识别三个方面对该框架的各个组成模块的关键技术进行了阐述。其中手势检测模块和识别管理模块能够辅助系统在复杂的背景中滤除掉不相关信息而选择性地搜索人手并根据上下文信息对手势识别任务重定向，从而避免了系统时刻都处于激活状态并对所有的手势动作都进行识别分析，有效解决了Midas Touch问题；为了提高系统的性能，提出了一种鲁棒的面向实时交互的变形手势跟踪方法和基于小样本学习的模板匹配方法用于动态手势识别。评估结果表明，上述技术有效地提高了系统的实时性、准确性和鲁棒性。 3. 设计开发了一个支持快速原型开发的视觉手势工具箱系统 针对目前大多数视觉手势工具箱复杂难用的问题，设计开发了一个简单、易用、可扩展的手势工具箱系统IEToolkit，实现了本文所述的各种关键交互技术。它包含了构造一个基于视觉手势的交互系统所需要的方方面面，从事件模型、交互模型、数据流模型等几个方面对工具箱的组成结构进行了描述，并给出了一个基于IEToolkit的通用的软件系统开发流程，开发人员可以将更多的精力集中在具体的高层逻辑语义处理上，而不需要过多考虑底层的技术细节与支撑结构。应用实例及评估结果表明IEToolkit能够降低开发门槛，较好地支持基于视觉手势交互的应用系统的快速构造，具有较高的应用价值。 4. 基于上述研究成果设计开发了一系列典型的视觉手势交互系统 将上述理论模型与具体的交互技术进行有效结合，在视觉手势开发工具平台基础上开发了一系列典型的互动娱乐系统，在实践中对本文的研究成果进行了有效性验证。

Hybrid metal-base transistor with base of sulfonated polyaniline and fullerene emitter

We demonstrate hybrid vertical architecture transistors that operate like metal-base transistors, using n-type silicon as the collector, sulfonated polyaniline as the base, and C-60 fullerene as the emitter. Electrical measurements suggest that the sulfonated polyaniline base effectively screens the emitter from electric field variations occurring in the collector leading to the metal-base transistor behavior.

Study on early-stage development of conchospore in Porphyra yezoensis Ueda

Porphyra yezoensis Ueda (Rhodophyta) is a seaweed of economic importance with a typical dimorphic life cycle consisting of a leafy gametophyte and a filamentous sporophyte. Recently, it has been recognized as a model system for fundamental and applied studies in marine biological sciences. Conchospore, a major spore linking the two distinct multicellular phases in the life cycle, is most widely used in the breeding of P. yezoensis. In this paper, the early-stage development of conchospore, including the attachment and the cell wall formation, was studied with fluorescent reagents staining and Scanning Electron Microscopy detection. Results displayed: (I) the cell wall began to be generated after culturing for 4 h in the attached conchospores; (2) the initially released conchospores were plastids with some filmy, amorphous substance on the surface, and they attached to the fibers firmly via the actively secreted mucilaginous substances after their touch to the fibers; (3) cellulase and pectolase prohibited the attachment of conchospores in the different ways; and (4) only attached conchospores generated cell walls and developed normally, while the suspending ones could not. It indicated that the cellulose played crucial roles in the permanent attachment as the pectin did in the initial attachment. The conchospore attachment seemed to trigger the cell wall formation and the further development. Affects of light on the development of conchospores were also discussed. The results showed that high intensity (200 mu mol.m(-2).s(-1)) and long-wave (>= 580 nm) light facilitated the division rate of conchospores. (C) 2008 Elsevier B.V. All rights reserved.

虚拟现实辅助机器人遥操作技术研究

本文以水下机器人的遥操作作业为应用背景 ,提出并实现了虚拟现实技术和视觉感知信息辅助机器人遥操作实验系统 .该系统使用了 CAD模型和立体视觉信息完成遥操作机器人及其作业环境的几何建模和运动学建模 ,实现了虚拟作业环境的生成和实时动态图形显示 .采用了基于立体视觉的虚拟环境与真实环境的一致性校正、图形图像叠加、作业体与环境位姿关系建立、基于网络的监控通讯等关键技术 .在这个实验系统中 ,操作人员可利用所生成的虚拟环境 ,在多视点、多窗口作业状态图形和图像显示帮助下 ,实时动态地进行作业观测与机器人遥操作与运动规划 ,为先进遥操作机器人系统的实现提供了经验和关键技术 .