Twin Markovian field correlation on four-level attosecond polarization beats

Based on the phase-conjugate polarization interference between two two-photon processes, we obtained an analytic closed form for the second-order or fourth-order Markovian stochastic correlation of the four-level attosecond sum-frequency polarization beat (FASPB) in the extremely Doppler-broadened limit. The homodyne-detected FASPB signal is shown to be particularly sensitive to the statistical properties of the Markovian stochastic light fields with arbitrary bandwidth. The different roles of the amplitude fluctuations and the phase fluctuations can be understood physically in the time-domain picture. The field correlation has a weak influence on the FASPB signal when the laser has narrow bandwidth. In contrast, when the laser has broadband linewidth, the FASPB signal shows resonant-nonresonant cross-correlation, and drastic difference for three Markovian stochastic fields. The maxima of the two two-photon signals are shifted from zero time delay to the opposite direction, and the signal exhibits damping oscillation when the laser frequency is off-resonant from the two-photon transition. A Doppler-free precision in the measurement of the energy-level sum can be achieved with an arbitrary bandwidth. As an attosecond ultrafast modulation process, it can be extended intrinsically to any sum frequency of energy levels.

Two-photon asymmetric color-locking second-order stochastic correlation of attosecond polarization beats

Based on the phase-conjugation polarization interference between two two-photon processes, we theoretically investigated the attosecond scale asymmetry sum-frequency polarization beat in four-level system (FASPB). The field correlation has weak influence on the FASPB signal when the laser has narrow bandwidth. Conversely, when the laser has broadband linewidth, the FASPB signal shows resonance-nonresonance cross correlation. The two-photon signal exhibits hybrid radiation-matter detuning terahertz; damping oscillation, i.e., when the laser frequency is off resonance from the two-photon transition, the signal exhibits damping oscillation and the profile of the two-photon self-correlation signal also exhibits zero time-delay asymmetry of the maxima. We have also investigated the asymmetry of attosecond polarization beat caused by the shift of the two-photon self-correlation zero time-delay phenomenon, in which the maxima of the two two-photon signals are shifted from zero time-delay point to opposite directions. As an attosecond ultrafast modulation process, FASPB can be intrinsically extended to any level-summation systems of two dipolar forbidden excited states.

Coherent laser control in attosecond sum-frequency polarization beats using twin noisy driving fields

Based on the phase-conjugate polarization interference between two-pathway excitations, we obtained an analytic closed form for the second-order or fourth-order Markovian stochastic correlation of the V three-level sum-frequency polarization beat (SFPB) in attosecond scale. Novel interferometric oscillatory behavior is exposed in terms of radiation-radiation, radiation-matter, and matter-matter polarization beats. The phase-coherent control of the light beams in the SFPB is subtle. When the laser has broadband linewidth, the homodyne detected SFPB signal shows resonant-nonresonant cross correlation, a drastic difference for three Markovian stochastic fields, and the autocorrelation of the SFPB exhibits hybrid radiation-matter detuning terahertz damping oscillation. As an attosecond ultrafast modulation process, it can be extended intrinsically to any sum frequency of energy levels. It has been also found that the asymmetric behaviors of the polarization beat signals due to the unbalanced controllable dispersion effects between the two arms of interferometer do not affect the overall accuracy in case using the SFPB to measure the Doppler-free energy-level sum of two excited states.

Effect of cryoprotectants on hatching rate of red seabream (Pagrus major) embryos

The objectives were to investigate the effect of cryoprotectants on the hatching rate of red seabream embryos. Heart-beat embryos were immersed in: five permeable cryoprotectants, dimethyl sulfoxide (DMSO), glycerol (Gly), methanol (MeOH), 1,2-propylene glycol (PG), and ethylene glycol (EG). in concentrations of 5-30% for 10, 30, or 60 min; and two non-permeable cryoprotectants: polyvinylpyrrolidone (PVP), and sucrose (in concentrations of 5-20% for 10 or 30 min). The embryos were then washed and incubated in filtered seawater until hatching occurred. The hatching rate of the embryos treated with permeable cryoprotectants decreased (P < 0.05) with increased concentration and duration of exposure. In addition, PG was the least toxic permeable cryoprotectant, followed by DMSO and EG, whereas Gly and MeOH were the most toxic. At a concentration of 15% and 30 min exposure, the hatching rate of the embryos immersed in PG was 93.3 +/- 7.0% (mean +/- S.D.), however. in DMSO. EG, Gly. and MeOH, it was 82.7 +/- 10.4, 22.0 +/- 5.7, 0.0 +/- 0.0, and 0.0 +/- 0.0%, respectively. Hatching rate of embryos treated with PVP decreased (P < 0.05) with the increase of concentration and exposure time, whereas for embryos treated with sucrose, there was no significant decrease in comparison with the control at the concentrations used. (C) 2008 Elsevier Inc. All rights reserved.

All-Optical Clock Recovery for 20 Gb/s Using an Amplified Feedback DFB Laser

We report all optical clock recovery based on a monolithic integrated four-section amplified feedback semiconductor laser (AFL), with the different sections integrated based on the quantum well intermixing (QWI) technique. The beat frequency of an AFL is continuously tunable in the range of 19.8-26.3 GHz with an extinction ratio above 8 dB, and the 3-dB linewidth is close to 3 MHz. All-optical clock recovery for 20 Gb/s was demonstrated experimentally using the AFL, with a time jitter of 123.9 fs. Degraded signal clock recovery was also successfully demonstrated using both the dispersion and polarization mode dispersion (PMD) degraded signals separately.

THEORETICAL AND EXPERIMENTAL STUDY OF POLARIZATION CHARACTERISTICS OF POLARIZATION MAINTAINING FIBER BASED ON WAVELENGTH-SWEEPING MODULATION

We analyze theoretically the polarization characteristics of polarization maintaining fiber and study the basic measurement principles of beat length and polarization extinction ratio of this kind of optical fiber. According, to the dependence of the phase difference between two orthogonally polarized modes (denoted Os HE(11)(x) and HE(11)(y)) transmitted in the polarization maintaining fiber on the light wavelength, we propose the wavelength-sweeping modulation method to measure the beat length and the model birefringence. Based on this technique, the hew length and polarization extinction ratio of the PANDA polarization maintaining fibers (PMFs) (provided by Yangtze Optical Fiber and Cable Company, Wuhan, China) were investigated in detail. Experimental results show good consistent with the theoretical ones. We find that this method shows high measurement precision with the advantages of clear measurement principle and easy to operate. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1466-1469, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25244

Dynamics of excited m-dichlorobenzene

Dynamics of excited m-dichlorobenzene is investigated in real time by femtosecond pump-probe method, combined with time-of-flight mass spectrometric detection in a supersonic molecular beam. The yields of the parent ion and daughter ion C6H4CI+ are examined as a function of the delay between the 270 and 810 nm femtosecond laser pulses, respectively. The lifetime of the first singlet excited state S-1 of m-dichlorobenzene is measured. The origin of this daughter ion C6H4CI+ is discussed. The ladder mechanism is proposed to form the fragment ion. In addition, our experimental results exhibit a rapid damped sinusoidal oscillation over intermediate time delays, which is due to quantum beat effects.

一种肤色干扰下的变形手势跟踪方法

介绍了一种基于单目视觉的肤色干扰下的变形手势跟踪方法.根据跟踪过程中所用到的基本手势特征,提出了一种基于PGH(成对几何直方图)的静态手势识别方法.为了解决跟踪过程中的肤色干扰问题,实现了基于Kalman滤波器的手势预测跟踪.为了解决跟踪过程中的初始化问题,提出了一种基于层次结构的跟踪初始化解决方案.实验结果表明,该方法能够在肤色干扰的情况下有效地对变形手势进行跟踪,并能够满足基于视觉的实时人机交互的要求.

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。

在线双向适应的笔手势界面框架研究

提出一个在线双向适应的笔手势界面框架,该框架针对传统笔手势界面中静态手势识别器不能支持用户的个性化输入以及用户在笔手势界面中面临的手势记忆问题,提出了在线双向适应的策略:一方面系统能够适应用户(系统可以在线支持用户的个性化输入);另一方面用户可以学习系统(用户可以学习系统提供的某些笔手势).该框架包括5个部分:(1)双向适应笔手势输入解释模型;(2)双向适应笔手势输入解释流程;(3)上下文优先级定义;(4)纠错和模糊消解界面;(5)在线笔手势查询帮助系统.在该框架的指导下作者开发了一个原型系统并进行了对比实验评估.结果表明该框架在可用性上具有较大的优势.

Effect of heat treatment on the parameters of crystal structure and degree of crystallinity of poly(aryl-ether-ether-ketone)

The variations of unit cell parameters and crystallite size of nine PEEK samples treated at various temperatures have been studied by using Wide-Angle X-ray Diffraction (WAXD), The results indicate a decrease in unit cell parameter a,b and c but an increase in crystallite size L(hkl) With the increase beat treatment temperature. Based on X-ray scattering intensity theory and using the graphic multipeak resolution method, the formula of degree of crystallinity (W-c,W-X) for PEEK is derived. The results calculated are compatible with the density measurement and calorimetry.

INVESTIGATION OF MICROSTRUCTURE AT IRON TETRAPHENYLPORPHYRIN MODIFIED CLASSY CARBON ELECTRODE BY XPS

Microstructure of the glassy carbon surface modified with iron tetraphenyfporphyrin (FeTPP) by heat treatment has been studied by XPS,, DTA and TG. XPS spectra of Fe 2P_3\2 level in FeTPP and iron tetraphenylporphyriu/glassy carbon (FeTPP/GC) have shown that a bond can be formed between the glassy carbon surface and both the central metal iron ion and the macrocyclic, ligand, which loses its four phenyl groups during the beat treatment. The relationship between the surface mierostructure of FeTPP/GC and the...

Cadmium toxicity to embryonic-larval development and survival in red sea bream Pagrus major

At 18 degrees C and 33 psu, 24 and 48 h LC50 values of cadmium (Cd) for red sea bream Pagrus major embryos were 9.8 and 6.6 mg l(-1), respectively, while 24,48, 72, and 96 h LC50 values for larvae were 18.9,16.2, 8.0, and 5.6 mg l(-1), respectively, indicating that embryos were more sensitive to Cd toxicity than larvae. Cd concentrations at >= 0.8 mg l(-1) led to low hatchability (0-90% in >= 0.8 mg l(-1) solutions vs. 97-100% in lower ones), delay in time to hatch, high mortality (38-100% vs. 1-10%), morphological abnormality (42-100% vs. 1-10%), reduced length (3.55-3.60 vs. 3.71-3.72 mm) in the embryos and larvae. They were Cd concentration dependent and potential biological significant endpoints for assessing the risk of Cd to aquatic organisms. Heart beat and yolk absorption of the larvae were significantly inhibited at some high concentrations but they were not as sensitive as other endpoints to Cd exposure. (C) 2008 Elsevier Inc. All rights reserved.

Effect of cryoprotectants on hatching rate of red seabream (Pagrus major) embryos

The objectives were to investigate the effect of cryoprotectants on the hatching rate of red seabream embryos. Heart-beat embryos were immersed in: five permeable cryoprotectants, dimethyl sulfoxide (DMSO), glycerol (Gly), methanol (MeOH), 1,2-propylene glycol (PG), and ethylene glycol (EG). in concentrations of 5-30% for 10, 30, or 60 min; and two non-permeable cryoprotectants: polyvinylpyrrolidone (PVP), and sucrose (in concentrations of 5-20% for 10 or 30 min). The embryos were then washed and incubated in filtered seawater until hatching occurred. The hatching rate of the embryos treated with permeable cryoprotectants decreased (P < 0.05) with increased concentration and duration of exposure. In addition, PG was the least toxic permeable cryoprotectant, followed by DMSO and EG, whereas Gly and MeOH were the most toxic. At a concentration of 15% and 30 min exposure, the hatching rate of the embryos immersed in PG was 93.3 +/- 7.0% (mean +/- S.D.), however. in DMSO. EG, Gly. and MeOH, it was 82.7 +/- 10.4, 22.0 +/- 5.7, 0.0 +/- 0.0, and 0.0 +/- 0.0%, respectively. Hatching rate of embryos treated with PVP decreased (P < 0.05) with the increase of concentration and exposure time, whereas for embryos treated with sucrose, there was no significant decrease in comparison with the control at the concentrations used. (C) 2008 Elsevier Inc. All rights reserved.

轮-腿复合移动机器人构型控制及越障策略

本文构型和越障控制研究的是如何控制机器人的姿态和如何控制机器人以一系列的构型翻越障碍物,构型及越障控制是轮-腿复合移动机器人技术领域的研究重点,针对轮-腿复合移动机器人的结构特点以及早期方法存在的不足,本文提出了在不平整地面上的构型控制方法和针对沟、坎典型地形环境的越障控制策略,并利用六轮-腿复合移动机器人试验平台开展了验证实验。