一种基于光学定位的自由式三维超声系统研发

自由式三维超声成像是一种新型的采用二维超声原理进行任意部位三维成像的设备,可以在传统的二维超声探头上固定用于空间定位的标记物,对扫描对象进行任意部位、大范围的三维扫描成像。文章介绍了一种可应用于微创手术导航的自由式三维超声成像系统,并详细分析了当前基于距离加权的三维超声重建算法的性能和优缺点。通过对体模和动物器官的超声图像扫描,并使用三维重建系统分别进行超声三维重建,得出了比较满意的结果,验证了三维重建算法及三维重建系统的可行性和有效性。     

基于VTK的医学图像重建与三维交互式方法的实现

为实现医学图像的重建与三维空间的交互式操作,使用可视化工具包VTK进行医学图像的三维重建并实现交互操作。通过在个人PC机上进行实验,采用体绘制算法重建出了高质量的三维物体,顺利地实现了三维交互操作并描述了详细的步骤。结果表明基于VTK的三维重建并通过在三维空间中添加回调函数来完成操作事件的拦截与响应是可行的。     

面向机械臂操作的视觉信息实时重建方法

现阶段的机械臂技能传授方法主要通过三维实时重建技术搭建虚拟空间进行模拟训练。然而人与机械臂视角不同，传统视觉信息重建方法由于重建误差大、时间长，而且实验环境苛刻、所需传感器较多等原因，导致机械臂在虚拟空间内习得的技能不能很好地迁移于现实环境。针对以上问题，提出了一种面向机械臂操作的视觉信息实时重建方法。首先，通过Mask-RCNN(Mask-Region Convolutional Neural Network)对实时采集到的RGB图像提取信息；然后，将提取后的RGB图像及其他视觉信息联合编码，并通过ResNet-18将视觉信息映射为机械臂操作空间的三维位置信息；最后，为减小重建误差，提出了一种聚类簇中心距离受限离群值调整方法（CC-DIS），并利用OpenGL(Open Graphics Library)将调整后的位置信息可视化，完成机械臂操作空间三维实时重建。实验结果表明，所提的实时重建方法具有较快的重建速度和较高的重建精度，完成一次三维重建仅需62.92 ms，重建速度高达每秒16帧，重建相对误差约为5.23%，能有效用于机械臂技能传授任务。     

基于多幅图像的三维重建

针对当前三维重建系统中大量的交互和频繁的失真,根据运动进行物体三维重建的原理,设计了一个简便易操作的三维重建系统.首先经过相机标定,立体匹配点,进而运用双视点三维重建原理即三角测量得到三维坐标:然后运用运动的连续性,综合多视点下的三维信息结合图像特征点的二维局部属性进行优化,最后经过三角剖分和纹理渲染得到物体真实的形状.与传统的三维重建系统相比,该系统能够在用户交互很少的情况下进行三维重建,且能重建出完整的低失真的三维模型.     

基于虚拟力引导的人机协同目标抓取方法

针对力反馈遥操作中传统人工势场法无法适应于机械臂整体的避障以及在作业过程中操作者难以控制机械臂到达所需位姿的问题,提出了一种基于虚拟力引导的人机协同目标抓取方法。力反馈设备向操作者提供力觉交互。通过结合人工势场法和虚拟夹具,构建管道形虚拟力场,生成实时虚拟力引导,实现协助操作者完成从端机器人的整体避障任务并在完成避障后引导机器人返回预定义路径并趋近目标点。当进行抓取任务时,构建锥形虚拟力场,实现协助操作者操作机械臂到达目标位置和姿态。此外,提出了一种机器人运动限制方法以降低操作者的操作失误对抓取任务的影响。实验证明,该方法能有效提高目标抓取操作的成功率和操作效率。     

虚拟手术中的模型实时绘制

实时的视觉反馈在虚拟手术中可以加强操作者的沉浸感。该文分析了体绘制和面绘制的优缺点,在系统实时性的要求下,实现了基于立体纹理映射的三维体模型的面绘制。算法在容许实时交互的同时,为操作者提供了真实感较强的视觉反馈。由于文中立体纹理生成及纹理坐标计算的特殊性,对虚拟手术中的拉压变形和切割等操作也能很好地处理。     

GPU并行计算加速的实时可视外壳三维重建及其虚实交互

针对现有的基于图像的三维重建方法难以实现真实物体的快速三维重建,无法满足虚实交互等应用需求的问题,提出一种基于GPU并行计算的实时三维重建及其虚实交互方法.首先把物体所在空间剖分成具有数据独立性的体素集合,结合可视外壳重建算法和精确行进立方体算法并行遍历每个体素得到体素状态序列;然后并行压缩体素状态序列得到非空体素集合,对非空体素进行并行三角形网格化,并利用图形硬件的多重纹理映射和可编程功能进行基于像素的纹理映射;最后假定虚拟物体的粒子为运动受限的拉格朗日流体粒子,重建物体网格顶点为流体边界,通过流体动力学方程的并行光滑粒子动力学方法求解来计算虚实交互.实验结果表明,该方法在GPU上进行完全并行求解,在32×32×32的空间剖分精度下,实现了实时三维重建和20帧/s左右的虚实交互计算,适用于计算机图形学和虚拟现实等领域中的虚实交互应用.     

基于数字人彩色图像的三维重建算法研究

对数字人彩色照片数据进行高质量的实时三维表面重建提出了一种新算法。该算法利用交互分割平台提取出彩色体数据中单个器官的三维表面点集,再根据对二值体数据滤波后的灰度值计算灰度梯度估算得到表面点的法向量。最后用带颜色的表面点来描述器官的三维表面,利用显卡OpenGL接口对表面点集进行三维显示。在微机环境下对美国数字人照片数据集中的肝脏和肺部两个器官进行了三维重建,在保证图像质量的前提下重建速度超过25帧/s。提出的算法能对高分辨率的彩色体数据进行高质量的实时三维表面重建。     

基于Web模式的医学图像三维重建与切割*

基于VTK开源软件包,结合Java applet编程,采用Java applet签名技术对程序进行签名认证。实现了Web方式下DICOM医学图像的三维重建,在重建的三维体上清晰显示出了人体器官的解剖结构,重建可在Internet上以Web模式跨平台运行,并可在三维体上进行交互切割和模拟手术开窗。分析用Java applet实现基于Web的医学断层图像三维重建是可行的,且实现的系统便于维护和升级,说明在临床上有很大应用价值。     

使用GPU编程的光线投射体绘制算法

将传统的光线投射体绘制算法在具有可编程管线的图形处理器(GPU)上重新实现.首先将体数据作为三维纹理保存在显存中,然后通过编写顶点程序和片段程序将光线进入点/离开点计算和光线遍历的计算移入GPU中执行,最后根据不同的采样点颜色混合公式实现不同的绘制效果.文中算法仅需绘制一个四边形即可完成三维重建.实验结果表明:在进行光照效果的重建时,该算法能够达到实时交互的绘制要求,并能实现半透明等复杂绘制效果.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate