多投影系统D-vision中双手6自由度力觉交互

D-vision系统(这里"D"有"Divide Screen"和"Duplex-Vision"双重含义)是一类基于PC机群的多投影虚拟现实系统(或简称多投影系统).给出D-vision系统中双手6自由度力觉交互的实现过程:在客户端协同控制两个力觉交互设备Spidar-G(Space Interface for Artificial Reality withGrip)实现双手协作交互,其次构造一个基于UDP的Socket类完成客户端和绘制服务器节点之间的通讯,传递跟踪球的位置、方向等信息;然后,通过分布绘制实现在大屏幕上无缝显示.最后实验结果表明:在D-vision系统中双手6自由度力觉交互是一种自然直观的人机交互方式.

面向虚拟现实的层次化交互手势建模与理解方法

虚拟现实中的交互手势包括多种不同类型,层次化建模方法避免了采用单一模型导致效率不高的问题.识别是一个由粗到精的过程,通过滑动窗技术实时提取手势的统计特征,实现手势类别的粗略划分,然后采用不同方法对各类手势进行分析.交互环境及上下文信息用以辅助手势的类别划分,提高了识别效率.最后通过虚拟家居系统对该方法进行了验证.

虚拟现实人机交互的eGOMS模型研究

采用心理学和计算机技术相交叉的研究方法,对人机交互中人的认知过程的人类视知觉特征和心理加工机制与特点等进行了细致的探讨;结合虚拟环境中人机交互过程的不确定性、连续性和实时反馈性以及交互可用性评价指标的多样性等特点,提出了适用于虚拟现实人机交互的扩展GOMS(eGOMS)模型,克服了传统GOMS模型要求精确的用户操作、交互界面与实际应用相分离及评价指标单一的不足.以eGOMS模型为基础对PIBG交互范式进行了评估,PIBG为VR用户界面提供自然、隐式交互的手段,从而大大降低了用户在虚拟环境下交互的认知负荷.

Magnetic barrier on strained graphene: A possible valley filter

We put forward a two-terminal valley filter based on a bulk graphene sheet under the modulations of both a local perpendicular magnetic field and a substrate strain. When only one of the two modulations is present, no valley polarization can be generated. A combination of the two modulations leads to a different (but not opposite) shifts of the K and K' valleys, which could be utilized to generate a valley-polarized current. The degree of the valley polarization can be tuned by the strain strength and the inclusion of a scalar potential. The valley polarization changes its polarity as the local magnetic field switches its direction.

2-C-支链-1,6-脱水吡喃葡萄糖的开环反应及吡喃烯糖的合成研究

在糖化学合成中，1,6-脱水吡喃糖不仅是合成具有生物活性低聚糖、糖共体、抗原、抗体以及天然产物等化合物重要原料，而且还是许多具有生物活性的天然产物的结构单元。同时，它还具有[3,2,1]的双环缩醛结构，使其在糖化学合成中具有高的立体选择性和区域选择性，同时减少了C-1 和C-6 位的保护和去保护的优点。此外，环内的缩醛开环后，又可以相应地在C-1 和C-6 位进行官能团转化以及糖苷化反应。 本文报道了一种新的1,6-脱水吡喃糖的合成方法，并设计合成了2-C-支链-1,6-脱水吡喃葡萄糖1-195、1-197、1-198 以及2-C-支链-6-硫代1,6-脱水吡喃葡萄糖1-225。到目前为止，1,6-脱水糖开环并进行糖苷化反应，存在选择性较差、产率低的缺点。我们发现，在乙腈做溶剂的条件下，NiCl5 能高立体选择性高产率地催化化合物1-195、1-197、1-198 开环并与ROH、RSH 发生糖苷化反应。在NiCl5-乙腈条件下，合成了一系列2-C-支链-α-糖苷和2-C-支链-β-硫代糖苷，并对2-C-支链1,6-脱水吡喃葡萄糖的生成机理以及开环机理进行了探讨。 烯糖在糖化学合成中是重要的起始原料，从Fischer 首次合成烯糖至今，一直不断地有新的合成方法出现。但目前文献报道的方法存在所用试剂有毒、价格贵和操作繁琐等缺点。我们对Fischer-Zach 方法进行了改进， 发现Zn-NaH2PO4-H2O 和Zn-PEG600-H2O 体系都能很好地合成烯糖。该方法具有条件温和、绿色环保、操作简单的优点。在Zn-NaH2PO4 溶液或Zn-PEG600 条件下，以溴代糖为原料，高产率地合成一系列的烯糖。 The 1,6-anhydrohexopyranoses are crucial subunits of myriad bioactive nature products, as well as important syntons of carbohydrate chemistry which have been extensively used to prepare the biologically potential oligosaccharides, glycoconjugates, antibiotics, and structurally varied nature products. Their particular [3.2.1] bicyclic skeleton makes them have high regio- and stereo-control in a variety of reactions, and such structure avoids protecting hydroxyl groups at C1 and C6.Additionally, the cleavage of the internal acetal under acidic conditions could be beneficial for further transformations of functional group and glycosylation of the corresponding pyranosyl sugar at the C6 or C1 site. Herein we developed a novel approach to prepare the 1,6-anhydrohexopyranose, and synthesized the 2-C-branched-1,6-anhydrohexopyranose 1-195, 1-197, 1-198 and 2-C-branched-6-thio-1,6-anhydrohexopyranose 1-225. Until now, glycosylation of 1,6-anhydrohexopyranoses has been limited because of the low yields and low stereoselectivity. In this paper, we found that NiCl5-MeCN system could selectively cleave the ring of 1,6-anhydrohexopyranoses with alcohols and thiols at room temperature in high yields. A series of 2-C-branched-α-glycosides and 2-C-branched-β-thioglycosides have been synthesized via NiCl5-catalyzed. Furthermore, we investigated the formation and ring-opening mechanism of 2-C-acetylmethyl-1,6-anhydrohexopyranose. Glycals are significant starting material in carbohydrate chemistry. After the Fischer-Zach method for forming glucal was reported for the first time, the numerous synthetic methods for glycals have been explored. However, there are several drawbacks in the existing methods, such as the usage of very expensive and toxic reagents, intricate operation, and the influence of acid-sensitive and base-sensitive functional group. We improved the Fischer-Zach method and developed a facile, mild and environmentally benign methodology towards the synthesis of the glycals in Zn-NaH2PO4-H2O or Zn-PEG600-H2O system. Our method involves the treatment of glycosyl bromides with Zn in NaH2PO4 aqueous solution or PEG600-H2O at room temperature, affording various glycals in excellent yields.

生物催化的Baeyer-Villiger氧化反应研究

Baeyer-Villiger氧化反应是一种很重要的化学反应，产生的许多中间体或产物可以被用来生产多种化学产品和药物。此反应具有多功能性，可以氧化多种羰基化合物，但是化学方法中的必需反应物——氧化剂在生产、储存、运输、反应的过程中都存在很多的不安全因素，反应的立体选择性也不强，而生物转化则具有底物选择性、立构选择性、化学选择性、对映选择性等一般化学反应中不具备的优点，在精细化工中占有很大的优势。在工业生物催化中有很好的应用前景。 为了研究生物催化的Baeyer-Villiger反应，我们从本实验室保藏菌种中分离筛选出一株能够以环己酮作为唯一碳源的菌株，进行初步研究并对其产物进行GC/MS定性，探讨了pH，装液量，底物浓度，培养时间，温度以及转速等条件对细菌生长的影响，并进一步研究了细菌的底物广谱性。 此菌株经鉴定属于邻单胞菌属Plesiomonas sp.)， 根据正交试验，确定了菌的最佳生长条件：底物浓度为1mL/L，底物浓度过高对菌株生长有抑制作用，转速为150 rpm ，温度为30℃ ，pH为7.0； 此菌株转化环己酮的产物通过GC/MS检测含有内酯，表明此菌株能够催化Baeyer-Villiger氧化反应；此菌株还能够以与环己酮有相似结构的环己烷，环戊酮等作为唯一碳源生长，说明此菌株底物利用范围比较广，用途比较广泛。 Baeyer-Villiger oxidation is an important chemical conversion, its products and intermediates can be used to produce a lot of medicine and fine chemicals. Its success is largely due to its versatility: a variety of carbonyl compounds can be oxidized, a large number of functional groups are tolerated, the regiochemistry is highly predictable and so on, but the oxidants that the traditional chemistry way needs have a number of problem in their production, storage, transportation and reaction, Chemistry way has not a high stereochemistry yet. However, biotransformations have many attractive characters, such as substrate-, stereo-, chemo- and enantioselectivity, so it has a great advantage in the fine chemical industry and has a bright prospect in the industrial biological catalysis. In order to study Baeyer-Villiger oxidation, we isolated a strain which can utilize cyclohexanone as sole carbon source and had a primary research on it. Its product was identified by GC/MS. Effects of pH, volume, concentration of cyclohexanone, cultivating time, temperature and rotate speed on the growth of bacteria were discussed, and the other organic substrates were also studied. The strain was identified as Plesiomonas sp.. The result of orthogonal test made it sure that the best growth condition of the strain is: rotate speed 150 rpm, temperature 30℃, pH7.0, concentration of cyclohexanone1ml/L. There is caprolactone in the product of the fermentation with cyclohexanone as substrate by GC/MS,which indicated that the strain can catalyse Baeyer-Villiger oxidation.In addition,the strain can utilize other organic substrates having the similar structure with cyclohexanone such as cyclohexane, cyclopentanone, Swertiamarin as sole carbon source.So the strain can be applied extentively.

Influence of Hypericum perforatum Extract on Piglet Infected with Porcine Respiratory and Reproductive Syndrome Virus

To study the influence of Hypericum perforatum extract (HPE) on piglets infected with porcine respiratory and reproductive syndrome virus (PRRSV), enzyme-labeled immunosorbent assay (ELISA) and cytopathic effect (CPE) were used to determine in vitro whether HPE could induce swine pulmonary alveolar macrophages (PAMs) to secrete IFN-gamma, and whether PRRSV titers in PAMs were affected by the levels of HPE-induced IFN-gamma. HPE (200 mg kg(-1)) was administrated by oral gavage to piglets infected with the PRRSV in vivo to observe whether HPE affected the viremia, lung viral titers, and weight gain of piglets infected with PRRSV. The results showed that HPE was capable of inducing PAMs to produce IFN-gamma in a dose dependent manner and HPE pretreatment was capable of significantly reducing PRRSV viral titers in PAMs (P<0.01). Administration of HPE to the PRRSV-infected animals significantly (P<0.05) reduced viremia over time as compared with the PRRSV-infected animals. But there was not significant decrease in lung viral titers at day 21 post-infection between the HPE-treated animals and the PRRSV-infected control piglets. There were no significant differences in weight gain over time among the HPE-treatment animals, the normal control, and the HPE control animals. The PRRSV-infected animals caused significant (P<0.01) growth retardation as compared with the HPE controls and the normal piglets. It suggested that HPE might be an effective novel therapeutic approach to diminish the PRRSV-induced disease in swine.

面向虚拟现实的多显示环境

在虚拟现实领域，面对大型三维场景的设计、开发以及漫游，以小组为单 位的同一地点的协同工作模式已经成为主流，多显示环境可以为用户提供多视 点、多设备、多种交互方式，同时能够实现便捷的信息共享。但是多显示环境 应用在虚拟现实领域还存在以下问题：1）现有的多显示环境不能很好的支持虚 拟现实领域现有的工作模式，缺乏一个较为完善的系统框架作为中间层将多显 示环境与工作模式进行融合；2）如何将多显示环境下的不同交互技术集成到系 统框架中，用以完成虚拟现实协同工作中的交互任务，是系统框架需要解决的 关键问题。 为了有效解决以上问题，本文首先进行多显示环境下的交互任务分析，设 计并实现了一个面向虚拟现实的多显示环境系统框架 MDE-VR，该框架能够很 好的集成底层物理多显示环境并支持上层协同工作模式，其主要模块有图形绘 制、输入重定向、图像重定向等。由于异质 MDE 中的一些显示设备图形绘制 较差，它们可能无法实时绘制3D图形，于是本文在 MDE-VR 框架中采用集中 式绘制方式解决这一问题。之后本文分析了用户在各个显示空间的操作类型， 划分了协同工作环境中的成员角色，并且提出了一种多显示环境下的本地协同 工作机制。该机制能够很好的支持多人共同完成交互任务。在此基础上， MDE-VR 框架设计了空间无缝交互和空间内聚交互两种不同的交互技术，方便 用户操纵公共显示屏幕和其他用户的私有显示屏幕。 最后本文开发了一个 3D场景规划系统，该系统实现了MDE-VR 框架的集 中式图形绘制、鼠标重定向、图像重定向等功能，支持用户使用两种交互技术 对公共显示空间和其他用户私有显示空间的操纵，支持多人在同一地点进行场 景规划的协同工作。它将多显示环境应用到场景规划领域，实现了更友好的人 机交互方式。

三维用户界面在城市规划系统中的应用

城市规划是城市政府为达到城市发展目标而对城市建设进行的安排。传统的基于物理模型的城市规划存在着修改成本高、效率低等问题。虽然虚拟现实（VR）技术可以为设计人员提供真实的三维呈现，但是当前的城市规划VR系统交互性差，难以实用。为了解决此问题，我们在虚拟现实环境中研究并开发了多通道三维用户界面。 本文先从技术和应用两个层面对三维用户界面进行了综述。在技术层面，分析了三维用户界面的定义和特征、三维交互设备、三维交互任务、三维交互隐喻、三维交互技术、多通道设计方法；在应用层面，调查了国内外有影响力的三维用户界面原型系统。 城市规划交互任务种类繁多，可以从三维用户界面通用交互任务和城市规划系统特有交互任务两个层次进行分析。三维用户界面通用任务包括漫游、选择、操作、系统控制四个交互任务，城市规划特有交互任务包括道路规划、建筑物规划、植物规划、区域规划、地图操作、草地规划、系统状态维护等交互任务。 通过分析，发现用户有大量状态、操作工具的切换，而当前的虚拟现实技术由于缺乏合适的隐喻，操作不便。为了提高交互性，我们提出了个人交互面板PIP(personal interaction panel)隐喻，并从静态交互界面和动态交互方式两个方面对该隐喻进行了介绍。在静态交互界面方面，将WIMP界面元素通过PIP隐喻引入到三维空间中，降低了用户学习负担；在动态交互方式方面，采用基于向导的笔迹交互方式，提高了交互效率。 为了实现城市规划三维交互技术，提出了基于笔的双层多通道融合模型，该模型将笔手势、指点信息、语音等多通道输入信息与会话上下文、交互上下文、场景上下文等信息进行融合，体现了多通道交互在指称归结、二义性消除、容错性方面的优势。此外，提出了基于统计的用户多通道融合模式建模方法，通过在多通道上下文无关文法中引入了表达超时的终结符,实现了自适应时间约束机制。 在PIP隐喻和多通道融合模型的基础上，我们设计并实现了一组三维交互技术以便用户自然、高效地完成城市规划中的各种三维交互任务。

Effects of pressure and molecular weight on the miscibility of polystyrene and cyclohexane

With the aid of Sanchez-Lacombe lattice fluid theory (SLLFT), the phase diagrams were calculated for the system cyclohexane (CH)/polystyrene (PS) with different molecular weights at different pressures. The experimental data is in reasonable agreement with SLLFT calculations. The total Gibbs interaction energy, g*(12) for different molecular weights PS at different pressures was expressed, by means of a universal relationship, as g(12)* =f(12)* + (P - P-0) nu*(12) demixing curves were then calculated at fixed (near critical) compositions of CH and PS systems for different molecular weights. The pressures of optimum miscibility obtained from the Gibbs interaction energy are close to those measured by Wolf and coworkers. Furthermore, a reasonable explanation was given for the earlier observation of Saeki et al., i.e., the phase separation temperatures of the present system increase with the increase of pressure for the low molecular weight of the polymer whereas they decrease for the higher molecular weight polymers. The effects of molecular weight, pressure, temperature and composition on the Flory Huggins interaction parameter can be described by a general equation resulting from fitting the interaction parameters by means of Sanchez-Lacombe lattice fluid theory.

Diel vertical migration of zooplankton following optimal food intake under predation

A model is developed to investigate the trade-offs between benefits and costs involved in zooplanktonic diel vertical migration (DVM) strategies. The 'venturous revenue' (VR) is used as the criterion for optimal trade-offs. It is a function of environmental factors and the age of zooplankter. During vertical migration, animals are assumed to check instantaneously the variations of environmental parameters and thereby select the optimal behavioral strategy to maximize the value of VR, i.e. taking up as much food as possible with a certain risk of mortality. The model is run on a diel time scale (24 h) in four possible scenarios during the animal's life history. The results show that zooplankton can perform normal DVM balancing optimal food intake against predation risk, with the profile of DVM largely modified by the age of zooplankter.

Viewing DVM via general behaviors of zooplankton: A way bridging the success of individual and population

In this paper, we viewed the diel vertical migration (DVM) of copepod in the context of the animal's immediate behaviors of everyday concerns and constructed an instantaneous behavioral criterion effective for DVM and non-DVM behaviors. This criterion employed the function of 'venturous revenue' (VR), which is the product of the food intake and probability of the survival, to evaluate the gains and losses of the behaviors that the copepod could trade-off. The optimal behaviors are to find the optimal habitats to maximize VR. Two types of VRs are formulated and tested by the theoretical analysis and simulations. The sensed VR, monitoring the real-time changes of trade-offs and thereby determining the optimum habitat, is validated to be the effective objective function for the optimization of the behavior; whereas, the realized VR, quantifying the actual profit obtained by an optimal copepod in the sensed-VR-determined habitat, defines the life history of a specific age cohort. The achievement of a robust copepod overwintering stock through integrating the dynamics of the constituent age cohorts subjected to the instantaneous behavioral criterion for DVM clearly exemplified a possible way bridging the immediate pursuit of an individual and the end success of the population. (c) 2005 Published by Elsevier Ltd.

沱沱河地区紫花针茅群落种间联结性分析

基于方差比率(VR)、χ~2检验和Jaccard指数对沱沱河地区紫花针茅群落12个主要种的种间联结性进行了分析.结果表明,紫花针茅群落优势种多物种间显著正关联,存在稳定共存的种间关系.建群种与其它物种间联结性不显著,在群落中能够稳定存在并占据优势生态位,群落处于植被演替过程的一个相对稳定的阶段.伴生种或次优势种之间联结显著,在群落中表现出很强的依赖性,分布易受其它物种的影响,在群落中不能稳定存在且只占据劣势生态位.根据种间联结性的分析结果,将紫花针茅群落分为2个不同的生态种组,但这2个生态种组并不具有明显的界限,它们之间存在着直接或间接的联系.

单相机全向立体视觉研究

折反射全向成像系统是由普通透视相机和反射镜面组成的全向成像装置，可实时获取360°无需拼接的全景图像，近年来已成为研究热点并在视频会议、三维重建和移动机器人导航等领域有着广泛的应用。 本文主要对单相机全向立体视觉系统的设计、标定、匹配以及三维重建展开研究。介绍了一种可实时获取全向三维信息的折反射全向立体视觉光学装置OSVOD（Omnidirectional Stereo Vision Optical Device），OSVOD由两个双曲面镜和一个普通透视相机组成。其中两个双曲镜面上下同轴、间隔一定距离固定在一个玻璃筒内，下镜面中间开有一孔，上镜面通过下镜面的孔在相机像平面上成像，这样空间一点经上下反射镜的反射在像平面上有两个像点，用一个相机实现了立体视觉。两镜面的共同轴和相机镜头的光轴共线，共同焦点和镜头的光心重合，该配置能保证系统满足单一视点约束SVP（Single View-Point）。本结构配置也使系统的外极线呈一系列的放射线，对应点匹配简单。此外两镜面的间隔安装也使得系统的等效基线较长，从而具有较高的精度。 本文第一部分对当前的各种全向成像方法进行了简单介绍，并对各方法的特点做了归纳。第二部分介绍折反射全向视觉的研究现状，就各种反射镜面的成像特点做了对比。 第三部分介绍OSVOD的设计方法，包括机构的设计和镜面的设计，并对设计的结果做了误差分析。 第四部分是OSVOD的标定研究。给出了一种包括OSVOD中相机和镜面位置关系在内的系统参数的标定方法。该方法利用空间坐标已知的标定点在像平面上成的像，结合系统成像模型反算出标定点的空间坐标，再利用标定点的已知空间坐标和反算出的空间坐标建立方程，运用基于Levenberg-Marquardt的反向传播算法(backpropagation)标定相机与反射镜面间的安装偏差。该标定方法可推广到所有的折反射成像系统。 第五部分是基于全向图像的匹配研究。针对系统获取的立体图像对之间成像比例存在较大的差异，首先将图像展开成柱面投影图像，然后就下镜面成像展开的柱面做Canny边缘检测，得到了图像的边缘点；就得到的边缘点在展开的两幅柱面图像上做直接相关匹配。最后将获取的匹配点做一致性校验，并对一致性校验通过的匹配点做三维计算，生产稀疏的三维图像。 最后是结论和将来的工作展望。

基于单相机的全向立体视觉关键技术研究

获取全向三维信息对移动机器人导航和行动规划具有重要意义。尽管有许多其他方法可以完成这一任务，如超声传感器和激光测距仪，但是折反射立体视觉系统在大多数情况下可以获得更高的精度和更大的视场，并且不消耗额外的能量。本文采用了一种新型的折反射全向立体视觉光学装置(OSVOD)进行立体视觉的研究，OSVOD是由两个双曲面镜和一个透视相机所组成的系统，能够由单幅图像实现立体视觉。 本文重点对单相机全向立体视觉系统的标定、单幅图像匹配、运动估计和多目匹配这三项最关键的技术进行了研究。在系统标定方面，给出了一种包括OSVOD中相机和镜面位置关系在内的系统参数的标定方法。该方法利用空间坐标已知的标定点在像平面上成的像，结合系统成像模型反算出标定点的空间坐标，再利用标定点的已知空间坐标和反算出的空间坐标建立方程，运用基于Levenberg-Marquardt的反向传播算法标定相机与反射镜面间的安装偏差。该标定方法可推广到所有的折反射成像系统。 在单幅图像匹配方面，针对系统获取的立体图像对之间成像比例存在较大的差异和畸变的问题，将图像展开成柱面投影图像和俯视投影图像，并提出了一种三步算法，首先匹配非歧义的点，从而将匹配划分为小的独立的子问题，并且每条极线只匹配到最远的特征点，从而避免在远端的不可靠匹配。在随后的动态规划算法中，设计了一个特定的能量函数，对不同的纹理强度和置信程度分别加权，得到了可靠的全向致密深度图。 在运动估计与多目匹配方面，以Harris角点做为待匹配的特征，由相关性得到初匹配结果。该结果中不可避免地存在误匹配，采用随机采样一致算法来得到运动估计。完成运动估计后，利用不同位置得到的图像进行了基于边缘检测的多目匹配，快速准确地获取了障碍物信息。