基于非线性渐变式颜色映射的LIC改进算法

线积分卷积（LIC）算法展现的纹理反映了整个矢量场的方向结构,但却不能展现矢量场的强度大小。针对此问题提出基于非线性渐变式颜色映射的LIC改进算法,将矢量场强度与白噪声结合作为LIC的输入纹理,运用FastLIC思想并划分纹理区域同步执行LIC运算来提高算法效率;再将矢量场强度作非线性变换,根据渐变式颜色映射方案使用OpenCV处理引擎并行实现矢量场强度的颜色映射; 最后由LIC得到的灰度纹理和颜色映射结果确定合成系数并构造累计函数增强两者结果,再进行线性合成运算得到最终的可视化效果。在对全球海洋流场和风场两种典型的矢量场进行可视化以及与其他算法对比实验表明,改进算法得到的可视化效果纹理清晰,较好地展示出矢量场的方向和强度,能够更准确地反映矢量场的全方位信息和局部变化情况。     

飞行器表面矢量场数据动态纹理可视化方法

面向飞行器表面流场数据可视化的应用需求,提出一种基于线性卷积（LIC）及纹理平流（IBFVS）相结合的动态纹理可视化方法。算法通过将IBFVS方法的背景随机噪声替换为LIC纹理方式,结合了LIC纹理结果对比度高及IBFVS方法生成速度快的优势;针对LIC绘制速度慢的不足,利用GPU对曲面矢量场投影并插值,生成规则矢量数据场;用GPU对LIC部分进行并行加速,有效提高了LIC纹理图像产生速度;将LIC结果图像加入到IBFVS进行平流,生成纹理图像,最后加入颜色映射,丰富流场信息。实验结果表明,该方法生成的飞行器表面动态纹理图像对比度高,清晰度强,实时绘制性能好。     

二维和三维矢量场的可视化

矢量场可视化用来帮助人们直观理解二维和三维矢量场。由于目前的矢量场可视化方法只能展示二维矢量场的方向而不能展示强度,并且对于三维矢量场可视化的效果不太令人满意,因此本文提出了用线积分卷积来实现二维平面矢量场可视化,以及三维空间矢量场可视化的方法。对于线积分卷积中的流线跟踪,利用扩展的Bresenham画线算法的思想,实现了二维平面和三维空间流线的跟踪,并且通过建立一个二维表和三维表来分别存储二维平面矢量场和三维空间矢量场中每个点在流线中的上一个点和下一点的位置,来避免传统流线跟踪方法的冗余计算,提高了效率。对于二维平面矢量场,把线积分卷积的结果和矢量的强度进行加权平均,从而利用输出图像的纹理和颜色,共同来表现矢量场的方向和强度。对于三维空间矢量场,利用体线积分卷积（Volume Line Integral Convolution, Volume LIC）的方法来得到输出体纹理,并且用光线投射的体渲染方法来展示三维空间矢量场。结果显示出本文的方法能够清晰直观的看到二维平面矢量场和三维空间矢量场。     

矢量场可视化线积分卷积方法研究与系统设计

随着矢量场数据规模的增加,不论是采用流线还是基于LIC技术绘制流场,其绘制速度都是评价其性能的重要指标,此外由于流线数量增加,流线会在临界点附近产生长流线汇聚问题,导致视觉混乱,冗余计算过多等问题。为了解决上述问题,提出了改进的平坦种子生成策略和FSeedLIC算法,设计并实现了矢量场可视化系统。通过实验表明采用改进的平坦种子生成策略的流线生成算法其加速效果平均能达到70%,产生的流线更加均匀,解决了长流线在密集区域汇聚的问题;FSeedLIC算法相对LIC算法在得到相同的可视化效果的条件下,其加速比平均在60%以上。     

基于GPU加速的3D矢量场改进VolumeLIC绘制技术

纹理绘制技术通过纹理线条和颜色变化能够细致且生动地表现2D矢量场的速度、方向以及数据相关性等特征信息,但扩展到3D矢量场空间时,由于3D矢量场本身的空间特性容易造成纹理单元之间产生严重的视线遮挡问题,影响研究人员对矢量场内部固有属性特征的观察和分析.针对此问题,提出一种基于GPU加速实现的稀疏噪声纹理生成的改进3D矢量场Volume LIC绘制技术.在噪声生成部分,基于泊松盘分布以避免噪声点间的相互遮挡,采用Hilbert空间填充线遍历减少生成噪声点的规律性和人工痕迹,并通过高斯滤波核滤除高频区域生成稀疏高斯噪声.整个算法采用GPU+GLSL硬件加速机制,在噪声纹理采样时,利用GPU顶点颜色线性插值功能和片元计算方法有效地加速LIC纹理生成过程,并将卷积噪声和矢量场数据作为纹理传入GPU;采用光线投射算法实现LIC纹理的3D绘制显示,并通过光线提前终止技术和空白空间跳跃技术有效提升绘制效率;同时提供多种有效的交互分析手段查看流场内部特征.实验结果表明,该方法生成的3D纹理图像清晰、绘制效率高,能够有效地缓解3D复杂矢量场卷积数据过多引起的遮挡与混乱现象,具备良好的可视化效果.     

一种新的VolumeLIC可视化方法

矢量场可视化是科学计算可视化中最具挑战性的研究课题之一,为了能在二维屏上直观显示三维矢量场,将基于纹理的LIC方法拓展到三维矢量场可视化,通过设计稀疏线噪声纹理并配合斜坡卷积核提高VolumeLIC图象质量,显著增强空间深度感,并采用光线投射直接体绘制方法生成VolumeLIC图象,另外,针对循环动画的突兀现象,提出HRCK（Hanninged RampConvolutionKernel)法生成流场的VolumeLIC循环动画,提出VolumeLICProbe交互洞察三维矢量场内部信息,通过实例表明,本文所提方法具有良好的可视化效果,交互方便,并已应用地幔可视化等领域。     

基于拓扑法的与时间相关二维矢量场的可视化

分析与时间相关二维矢量场可视化的拓扑法，并针对其在检测封闭流线时依赖网格以及不能对封闭流线精确定位的问题，进行改进。通过运用特征流场对临界点跟踪以及鞍状连接符对流面积分，提出一种检测封闭流线的方法。该方法不依赖于网格，解决了封闭流线精确定位的问题。实验结果表明本文提出的算法为与参数相关二维矢量场可视化提供一个基本框架。     

一种流体艺术风格的自适应LIC绘制方法

把LIC算法应用到非真实感绘制中,提出一种自适应流体艺术图的LIC绘制方法.对源图像亮度分量计算切矢量场,然后对其进行增强、平滑处理获得结构矢量场;通过随机扰动源图像获得纹理参考图像;根据结构矢量场和纹理参考图像的局部特征产生可变的LIC积分步长和步数,自适应地处理纹理参考图像;最后对绘制效果进行颜色渲染,生成具有丰富颜色特征的流体艺术图.实验表明,该方法能够较好地模拟诸如梵高画的流体艺术风格,呈现生动、灵活的波动感.     

着色噪声的LIC算法

LIC方法是用于矢量数据可视化的一种纹理合成方法，该文中提出着色噪声的LIC方法CLIC，按照速度矢量的方向对传统LIC方法中使用的白色噪声进行着色，生成的图象中可以区分不同的运动方向，这一方法应用在爆炸场数值模拟，可以清晰地展示爆炸场的复杂的流场特征。     

一种非结构矢量场的线卷积积分方法

传统的结构化LIC方法不适用于非结构矢量场数据处理的主要原因有两个，一是矢量幅度的表现力不强，二是因分辨率等因素无法有效地应用于采样点位置随机的矢量场．为解决上述问题，可以采用如下方法：在DDA曲线的生成过程中，采用基于数值的计算方法替代结构化LIC中基于网格的计算方法，从而有效地保证了处理结果的分辨率；在DDA曲线的卷积积分（LIC）处理过程中，采用区域标记的策略替代快速LIC方法中的线标记策略，一方面，因为被标记的采样点不再作为以后各轮DAA曲线生成的起始点，从而可以有效地减少计算量；另一方面，区域标记方法能够使LIC处理的结果稀疏化，表现为矢量场中幅度大的区域矢量线密集，而幅度小的区域矢量线稀疏，从而有效地提高矢量场幅度、结构的表现力．     

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