Automatic Creation of Object Hierarchies for Radiosity Clustering

Using object clusters for hierarchical radiosity greatly improves the efficiency and thus usability of radiosity computations. By eliminating the quadratic starting phase very large scenes containing about 100k polygons can be handled efficiently. Although the main algorithm extends rather easily to using object clusters, the creation of 'good' object hierarchies is a difficult task both in terms of construction time and in the way how surfaces or objects are grouped to clusters. The quality of an object hierarchy for clustering depends on its ability to accurately simulate the hierarchy of the energy flow in a given scene. Additionally it should support visibility computations by providing efficient ray acceleration techniques.
In this paper we will present a new approach of building hierarchies of object clusters. Our hybrid structuring algorithm provides accuracy and speed by combining a highly optimized bounding volume hierarchy together with uniform spatial subdivisions for nodes with regular object densities. The algorithm works without user intervention and is well suited for a wide variety of scenes. First results of using these hierarchies in a radiosity clustering environment are very promising and will be presented here.
The combination of very deep hierarchies (we use a binary tree) together with an efficient ray acceleration structure shifts the computational effort away from form factor and visibility calculation towards accurately propagating the energy through the hierarchy. We will show how an efficient single pass gathering can be used to minimize traversal costs.     

VARIANT: A System for Terrain Modeling at Variable Resolution

We describe VARIANT (VAriable Resolution Interactive ANalysis of Terrain), an extensible system for processing and visualizing terrains represented through Triangulated Irregular Networks (TINs), featuring the accuracy of the representation, possibly variable over the terrain domain, as a further parameter in computation.VARIANT is based on a multiresolution terrain model, which we developed in our earlier research. Its architecture is made of a kernel, which provides primitive operations for building and querying the multiresolution model; and of application programs, which access a terrain model based on the primitives in the kernel.VARIANT directly supports basic queries (e.g., windowing, buffering, computation of elevation at a given point, or along a given line) as well as high-level operations (e.g., fly-over visualization, contour map extraction, viewshed analysis). However, the true power of VARIANT lies in the possibility of extending it with new applications that can exploit its multiresolution features in a transparent way.     

径向基函数及移动网格在Euler方程数值计算中的应用

基于二维Euler方程,在利用弹簧技术的移动非结构三角形网格上给出了一种基于紧支径向基函数重构的ENO型有限体积格式,方法的主要思想是先对每一个三角形单元构造插值径向基函数,而在计算交界面的流通量采用两点高斯积分公式以保证格式的整体精度,时间离散采用三阶TVD Runge-Kutta方法。最后用该格式对一些典型算例进行了数值模拟,结果表明该方法计算速度快,对间断有很好的分辨能力。     

Cellular-Logic Devices: Concepts and Applications

Cellular-logic devices, using a parallel processing element for each element of a rotating memory, allow fast data search and manipulation.     

GEncode: Geometry-driven compression for General Meshes

Performances of actual mesh compression algorithms vary significantly depending on the type of model it encodes. These methods rely on prior assumptions on the mesh to be efficient, such as regular connectivity, simple topology and similarity between its elements. However, these priors are implicit in usual schemes, harming their suitability for specific models. In particular, connectivity‐driven schemes are difficult to generalize to higher dimensions and to handle topological singularities. GEncode is a new single‐rate, geometry‐driven compression scheme where prior knowledge of the mesh is plugged into the coder in an explicit manner. It encodes meshes of arbitrary dimension without topological restrictions, but can incorporate topological properties, such as manifoldness, to improve the compression ratio. Prior knowledge of the geometry is taken as an input of the algorithm, represented by a function of the local geometry. This suits particularly well for scanned and remeshed models, where exact geometric priors are available. Compression results surfaces and volumes are competitive with existing schemes.     

主动网络的概念应用及其范例

主动网络是可编程网络,主动网络中的网络结点具有计算能力,它能对流经本地的数据进行计算和修改,本文介绍了主动网络（active network)的应用,实现方案并通过具体实例Bowman和CANEs来阐述。     

Particle Swarm Optimization: Basic Concepts, Variants and Applications in Power Systems

Many areas in power systems require solving one or more nonlinear optimization problems. While analytical methods might suffer from slow convergence and the curse of dimensionality, heuristics-based swarm intelligence can be an efficient alternative. Particle swarm optimization (PSO), part of the swarm intelligence family, is known to effectively solve large-scale nonlinear optimization problems. This paper presents a detailed overview of the basic concepts of PSO and its variants. Also, it provides a comprehensive survey on the power system applications that have benefited from the powerful nature of PSO as an optimization technique. For each application, technical details that are required for applying PSO, such as its type, particle formulation (solution representation), and the most efficient fitness functions are also discussed.     

多分辨率建模方法及其在分布交互仿真中的应用

分析了基于MRM(多分辨率模型)仿真的关键技术、方法及其特点,阐述了大规模分布交互仿真中多分辨率模型的应用问题。     

上下文一致性错误及其处理对应用的影响

在普适计算环境中,上下文信息由于受到噪声等不可控因素的干扰,面临着一致性错误的问题。这些错误会影响应用的正常运行,使其表现异常甚至失效。目前已经有自动的一致性错误处理方法来保障应用所获取的上下文满足数据层面的一致性约束,然而在数据层面保持一致是否能提升应用的运行质量并不明确。系统地研究了这个问题,并基于一组真实的上下文感知机器人小车应用,设计了一系列受控实验,来分析和比较在模拟和真实世界中上下文一致性错误的处理方式对应用运行质量的改善程度及潜在的负面影响。利用该实验的分析结果,将有助于提高普适计算中上下文感知应用的运行质量。     

变精度双向S-粗集及其应用

提出基于副集的双向S-粗集,变精度双向S-粗集;给出基于副集的双向S-粗集,变精度双向S-粗集的数学结构;给出变精度双向S-粗集的存在背景和意义解释。变精度双向S-粗集是对双向S-粗集理论的完善和发展。     

Reinterpretable Imager: Towards Variable Post‐Capture Space,Angle and Time Resolution in Photography

We describe a novel multiplexing approach to achieve tradeoffs in space, angle and time resolution in photography. We explore the problem of mapping useful subsets of time‐varying 4D lightfields in a single snapshot. Our design is based on using a dynamic mask in the aperture and a static mask close to the sensor. The key idea is to exploit scene‐specific redundancy along spatial, angular and temporal dimensions and to provide a programmable or variable resolution tradeoff among these dimensions. This allows a user to reinterpret the single captured photo as either a high spatial resolution image, a refocusable image stack or a video for different parts of the scene in post‐processing. A lightfield camera or a video camera forces a‐priori choice in space‐angle‐time resolution. We demonstrate a single prototype which provides flexible post‐capture abilities not possible using either a single‐shot lightfield camera or a multi‐frame video camera. We show several novel results including digital refocusing on objects moving in depth and capturing multiple facial expressions in a single photo.     

Non Uniform Multiresolution Method for Optical Flow and Phase Portrait Models: Environmental Applications

In this paper we define a complete framework for processing large image sequences for a global monitoring of short range oceanographic and atmospheric processes. This framework is based on the use of a non quadratic regularization technique for optical flow computation that preserves flow discontinuities. We also show that using an appropriate tessellation of the image according to an estimate of the motion field can improve optical flow accuracy and yields more reliable flows. This method defines a non uniform multiresolution approach for coarse to fine grid generation. It allows to locally increase the resolution of the grid according to the studied problem. Each added node refines the grid in a region of interest and increases the numerical accuracy of the solution in this region. We make use of such a method for solving the optical flow equation with a non quadratic regularization scheme allowing the computation of optical flow field while preserving its discontinuities. The second part of the paper deals with the interpretation of the obtained displacement field. For this purpose a phase portrait model used along with a new formulation of the approximation of an oriented flow field allowing to consider arbitrary polynomial phase portrait models for characterizing salient flow features. This new framework is used for processing oceanographic and atmospheric image sequences and presents an alternative to complex physical modeling techniques.     

Spectral Element Methods on Unstructured Meshes: Comparisons and Recent Advances

Spectral element approximations for triangles are not yet as mature as for quadrilaterals. Here we compare different algorithms and show that using an integration rule based on Gauss-points for simplices is of interest. We point out that this can be handled efficiently and allows to recover the convergence rate theoretically expected, even with curved elements.     

MPEG-4变长解码器设计及VLSI实现

变长编码（Variable Length Codes，简称VLCs）由于其较强的数据压缩能力而被广泛应用在多媒体数据压缩领域，变长编码又分为传统的前缀码和具有错误恢复能力的可逆变长编码（Reversible Variable Length Codes，简称RVLCs）．传统VLCs的自身性质使它对信道错误的恢复能力很弱，RVLCs解码遇到传输错误时，充分利用了可用的数据．错误恢复能力强于VLCs．本文详细描述了传统VLCs和RVLCs解码器的解码算法和解码器的体系结构设计，最后，给出了一个基于MPEG-4 ASP@L5的变长解码嚣VLSI实现，结果表明，该实现完全适用于MPEG-4实时编解码系统．     

浅谈设计理念与方法在书籍设计中的运用

书籍设计是一个历史悠久的设计行当,从一开始手工作坊似的设计方式,到今天似乎轻点鼠标就可以完成的设计方法,书籍设计经历了大跨度的变迁。然而技术的提高所带来的设计方法的极大丰富并不能解决设计过程中的一切问题,只有在富有创造性的设计理念的指引下,设计方法才能发挥它的作用。     

Optofluidic waveguides: I. Concepts and implementations

We review recent developments and current status of liquid-core optical waveguides in optofluidics with emphasis on suitability for creating fully planar optofluidic labs-on-a-chip. In this first of two contributions, we give an overview of the different waveguide types that are being considered for effectively combining micro and nanofluidics with integrated optics. The large number of approaches is separated into conventional index-guided waveguides and more recent implementations using wave interference. The underlying principle for waveguiding and the current status are described for each type. We then focus on reviewing recent work on microfabricated liquid-core antiresonant reflecting optical (ARROW) waveguides, including the development of intersecting 2D waveguide networks and optical fluorescence and Raman detection with planar beam geometry. Single molecule detection capability and addition of electrical control for electrokinetic manipulation and analysis of single bioparticles are demonstrated. The demonstrated performance of liquid-core ARROWs is representative of the potential of integrated waveguides for on-chip detection with ultrahigh sensitivity, and points the way towards the next generation of high-performance, low-cost and portable biomedical instruments.     

Combined Negotiations in E-Commerce: Concepts and Architecture

Combined Negotiations are a novel and general type of negotiation, in which the user is interested in many goods or services and consequently engages in many negotiations at the same time. The negotiations are independent of each other, whereas the goods or services are typically interdependent. Using currently available technology for electronic negotiations, the user conducts each negotiation separately, and has the burden of coordinating and reconciling them. The inherent complexity of combined negotiations in B2C as well as B2B e-commerce calls for software support.In our research, we aim to devise a Combined Negotiation Support System (CNSS) to help the user conduct all the negotiations at the same time. The CNSS enables the user to control and monitor the progress of the negotiations, makes sure that the specified dependencies are respected, and applies user-defined strategy rules. We have designed such a CNSS which we call CONSENSUS. The architecture of CONSENSUS relies on workflow technology, negotiating software agents, and rule engine technology. The originality of this architecture lies in the fact that the user of CONSENSUS models the combined negotiation at build time using a workflow that captures the sequencing of the individual negotiations and the dependencies between them. At runtime, software agents are assigned to individual negotiations, and they participate in the combined negotiation as actors in the workflow. The user can monitor the progress of the combined negotiation as a whole, and the progress of individual negotiations via dedicated graphical user interfaces. We rely on rule engine technology to enable the agents to use negotiation strategies.The paper introduces combined negotiations with a usage scenario. Then, combined negotiations are detailed, along with the approach taken to cope with their complexity. Afterwards, we describe the functionality a CNSS should provide, and present the architecture of CONSENSUS, together with a discussion of the underlying concepts and technologies. Furthermore, we report on our prototype implementation of CONSENSUS and illustrate it with an example. A discussion of related and future work concludes the paper.     

Part and Complement: Fundamental Concepts in Spatial Relations

The spatial world consists of regions and relationships between regions. Examples of such relationships are that two regions are disjoint or that one is a proper part of the other. The formal specification of spatial relations is an important part of any formal ontology used in qualitative spatial reasoning or geographical information systems. Various schemes of relationships have been proposed and basic schemes have been extended to deal with vague regions, coarse regions, regions varying over time, and so on. The principal aim of this paper is not to propose further schemes, but to provide a uniform framework within which several existing schemes can be understood, and upon which further schemes can be constructed in a principled manner. This framework is based on the fundamental concepts of part and of complement. By varying these concepts, for example, allowing a part-of relation taking values in a lattice of truth values beyond the two-valued Boolean case, we obtain a family of schemes of spatial relations. The viability of this approach to spatial relations as parameterized by the concepts of part and complement is demonstrated by showing how it encompasses the RCC5 and RCC8 schemes as well as the case of egg–yolk regions.     

Algebraic Algorithmics: Theory and Applications

This article is a review of works on the algebra of algorithms, which is a new promising line of investigation in the field of algebraic algorithmics and is progressing rapidly in Ukraine and abroad. To this line belong explorations into a multilevel structural software design method developed at the Automatic Programming Department at the V. M. Glushkov Cybernetics Institute of the Academy of Sciences of Ukraine.