Local Exact Particle Tracing on Unstructured Grids

For analyzing and interpreting results of flow simulations, particle tracing is a well established visualization method. In addition, it is a preliminary step for more advanced techniques such as line integral convolution. For interactive exploration of large data sets, a very efficient and reliable particle tracing method is needed. For wind channel experiments or flight simulations, large unstructured computational grids have become common practice. Traditional approachs, based on numerical integration methods of ordinary differential equations however fail to deliver sufficiently accurate path calculation at the speed required for interactive use. In this paper we extend the local exact approach of Nielson and Jung in such a way that it can be used for interactive particle tracing in large data sets of steady flow simulation experiments. This will be achieved by sophisticated preprocessing using additional memory. For further visual enhancement of the streamline we construct an implicitly defined smooth Bézier curve that is used for ray tracing. This allows us to visualize additional scalar values of the simulation as attributes to the trajectory and enables the display of high‐quality smooth curves without creating any visualization geometry and providing a good impression of the spatial situation at the same time. ACM CSS: I.3.3 Computer Graphics—Line and curve generation; I .3.7 Computer Graphics—Raytracing; G.1.2 Numerical Analysis—Spline and piecewise polynomial approximation     

Air flow through a non-airconditioned bus with open windows

Open window buses without air-conditioning are a major mode of urban and inter-city transport in most countries. High occupancy combined with hot and humid conditions makes travel in these buses quite uncomfortable. In this study air flow through a bus has been studied that could be the basis for low cost and eco-friendly methods of increasing passenger comfort and possibly reduce drag. The aerodynamics of such a road vehicle has not been studied as previous investigations have been confined to vehicles with closed windows that present a smooth exterior to air flow. Using a 1:25 scaled Perspex model of an urban bus in Delhi, flow visualization was performed in a water channel. The Reynolds numbers were one-tenth of a real bus moving at 10 m/s. Smoke and tuft visualizations were also performed on an urban bus at 40 km/h. Numerical simulations were performed at the actual Reynolds number. Even though there were Reynolds number differences, the broad features were similar. Air enters the bus from the rear windows, moves to the front (relative to the bus) and exits from the front windows. Inside air velocity relative to the bus is about one-tenth of the free-stream velocity. The flow is highly three-dimensional and unsteady.     

Elimination of fictitious penetrating rays from PO and hybridization with AFIM

Physical optics (PO) is an approximation method for high‐frequency scattering and diffraction problems. But PO fields are inaccurate in the shadow region where the source is screened by the scatter. Two key factors of the error for PO are (i) edge diffraction coefficients and (ii) existence of fictitious penetrating rays. The correction with respect to the former has been extensively investigated by many authors using various ray techniques such as GTD, UTD, and UAT. On the other hand, the latter was identified recently by the authors. This paper proposes novel PO‐based calculation procedures termed PO‐AF and PTD‐AF, where PO and Aperture Field Integration Method (AFIM) are merged with the help of special elementary diffraction coefficients. These can uniformly cover the whole angular region and only the error factor (ii) is removed in PO‐AF while both (i) and (ii) are removed in PTD‐AF. The theoretical backgrounds of PO currents are discussed in terms of field equivalence theorem and visualization of EM waves. Next, new methods are proposed and their validity is numerically demonstrated for 2D scattering problems of a strip, a corner reflector, and a cylinder of circular arc. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 1–10, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20037     

川东二叠系生物礁油气藏的地震勘探技术

 生物礁油气藏是一种特殊的岩性油气藏，由于其地质特点的多样性和复杂性，使得生物礁的地震勘探难度很大。本文针对川东地区二叠系生物礁的地质特点和资料情况，以生物礁气藏为研究对象，从已知井井震响应特征分析出发，通过地震反射结构分析、神经网络波形分类处理、地震属性分析、三维可视化解释、多参数地震反演等多项地震特殊处理和解释方法，建立了生物礁和生物礁储层的判别模式，形成了有针对性的地震勘探配套技术。其中以伽马、补偿中子及声波为目标曲线的多参数地震反演技术对于预测和评价生物礁特别有效。     

Information Visualization Within a Digital Video Library

The Informedia Digital Video Library contains over a thousand hours of video, consuming over a terabyte of disk space. This paper summarizes the multimedia abstractions used to represent this video in prior systems and introduces the visualization techniques employed to browse and navigate multiple video documents at once.     

The Method of Dynamic Palette Construction in Realistic Visualization Systems

The paper describes the colour approximation problem and the method of dynamic palette construction is suggested for its solution. The method uses the graphic display palette based on the computed true colour of the individual picture. Some aspects of human colour perception are considered. Two metrics in colour space are introduced to estimate closeness of the suggested colour approximation. The method was applied to visualize 3D scenes generated by ray tracing.     

基于物联网技术的监狱人员定位可视化管理系统

提出了一种监狱人员定位可视化管理系统的设计和实现方法。该系统基于WLAN的RTLS定位技术,实现对服刑人员、干警、访客等人群的可视化定位管理。文章结合监狱的应用需求,首先给出了系统的总体设计原则;同时在总体原则约束下,对系统功能、总体实现方案、实现框图、应用流程、网络安全等部分进行阐述,给出了标签软硬件设计、定位管理系统的平台选型和软件架构;最后对设计的系统进行了测试。测试结果显示,该可视化定位管理系统的定位精度达到了预期效果。在进一步优化和完善后,即可大规模推广使用。