15285732
Animation of Bubbles in Liquid
We present a new fluid animation technique in which liquid and gas interact with each other, using the example of bubbles rising in water. In contrast to previous studies which only focused on one fluid, our system considers both the liquid and the gas simultaneously. In addition to the flowing motion, the interactions between liquid and gas cause buoyancy, surface tension, deformation and movement of the bubbles. For the natural manipulation of topological changes and the removal of the numerical diffusion, we combine the volume-of-fluid method and the front-tracking method developed in the field of computational fluid dynamics. Our minimum-stress surface tension method enables this complementary combination. The interfaces are constructed using the marching cubes algorithm. Optical effects are rendered using vertex shader techniques.
5396079
Fracturing Rigid Materials
We propose a novel approach to fracturing (and denting) brittle materials. To avoid the computational burden imposed by the stringent time step restrictions of explicit methods or with solving nonlinear systems of equations for implicit methods, we treat the material as a fully rigid body in the limit of infinite stiffness. In addition to a triangulated surface mesh and level set volume for collisions, each rigid body is outfitted with a tetrahedral mesh upon which finite element analysis can be carried out to provide a stress map for fracture criteria. We demonstrate that the commonly used stress criteria can lead to arbitrary fracture (especially for stiff materials) and instead propose the notion of a time averaged stress directly into the FEM analysis. When objects fracture, the virtual node algorithm provides new triangle and tetrahedral meshes in a straightforward and robust fashion. Although each new rigid body can be rasterized to obtain a new level set, small shards can be difficult to accurately resolve. Therefore, we propose a novel collision handling technique for treating both rigid bodies and rigid body thin shells represented by only a triangle mesh
7007390
Wrinkled flames and cellular patterns
We model flames and fire using the Navier-Stokes equations combined with the level set method and jump conditions to model the reaction front. Previous works modeled the flame using a combination of propagation in the normal direction and a curvature term which leads to a level set equation that is parabolic in nature and thus overly dissipative and smooth. Asymptotic theory shows that one can obtain more interesting velocities and fully hyperbolic (as opposed to parabolic) equations for the level set evolution. In particular, researchers in the field of detonation shock dynamics (DSD) have derived a set of equations which exhibit characteristic cellular patterns. We show how to make use of the DSD framework in the context of computer graphics simulations of flames and fire to obtain interesting features such as flame wrinkling and cellular patterns.
18405227
Controlling fluid animation with geometric potential
We propose a new fluid control technique that uses a geometrically induced potential field. Instead of optimizing the control forces exerted at each frame, as was done in previous work, a potential is added as an extra dimension to the simulation space which coerces the fluid inside this space to form the target shape. This type of shape control requires practically no additional computing by the Navier-Stokes solver at run-time, and adds little overhead to implementation. The confinement potentials are induced from geometric information given by animators, and so the control forces that take fluids to a lower potential can be decided in a preprocessing step. We show that a slightly generalized Navier-Stokes equation for fluids in potential fields can be simulated without changing the solver itself. A harmonic potential function can be quickly found with the Poisson solver which is already implemented as a part of the Navier-Stokes solver. 2 and 3 dimensional flows designed by common methods such as hand drawing, traditional shape modeling and key-framing, can be animated efficiently with our control technique. Copyright © 2004 John Wiley & Sons, Ltd.
378509
liquid: Context-Aware Distributed Queries
As low-level architectural support for context-aware computing matures, we are ready to explore more general and powerful means of accessing context data. Information required by a context-aware application may be partitioned by any number of physical, organizational, or privacy boundaries. This suggests the need for mechanisms by which applications can issue context-sensitive queries without having to explicitly manage the complex storage layout and access policies of the underlying data. To address this need, we have developed liquid, a prototype query service that supports distributed, continuous query processing of context data. This paper articulates the current need for such systems, describes the design of the liquidsystem, and presents both a room-awareness application and notification service demonstrating its functionality.
14840492
Towards Reusable Colored Petri Nets
Reuse has long been recognized as a key technology that can bring about signi cant productivity gains in software development. Code-level reuse is wellunderstood and frequently practiced. However, reuse in software requirements, another phase where much bene t can be expected, remains inadequately addressed. Hierarchical Colored Petri Net (HCPN) formalism has been successfully used on several large-scale industrial projects, and it includes features designed to enhance modularity and understandability of the model. Unfortunately, such features fall short of making HCPN reusable. In this paper, we provide formal de nitions of RCPN as a reuse extension to the HCPN. RCPN can reduce complexity and cost of modeling and analysis in requirements engineering phase and increase software development productivity. We demonstrate an application of RCPN by demonstrating how a RCPN component for water level monitoring system (WLMS) can be reused in a co ee vending machine (CVM) model.
209399506
SWAMI: a framework for collaborative filtering algorithm development and evaluation.
We present a Java-based framework, SWAMI (Shared Wisdom through the Amalgamation of Many Interpretations) for building and studying collaborative filtering systems. SWAMI consists of three components: a prediction engine, an evaluation system, and a visualization component. The prediction engine provides a common interface for implementing different prediction algorithms. The evaluation system provides a standardized testing methodology and metrics for analyzing the accuracy and run-time performance of prediction algorithms. The visualization component suggests how graphical representations can inform the development and analysis of prediction algorithms. We demonstrate SWAMI on the EachMovie data set by comparing three prediction algorithms: a traditional Pearson correlation-based method, support vector machines, and a new accurate and scalable correlation-based method based on clustering techniques.
10811173
EWS-Based Management Application Interface and Integration Mechanisms for Web-Based Element Management
Web-based network element management provides an administrator with the ability to configure and monitor network devices over the Internet using a Web browser. The most direct way to accomplish this is to embed a Web server [Embedded Web Server (EWS)] into a network device, and use that server to provide a Web-based management user interface constructed with HTML, graphics, Java and other features common to Web browsers. In this paper we present EWS-based management application interface mechanisms for use between embedded management applications and embedded Web servers. We propose a guideline for choosing an efficient interface mechanism, which is based on the characteristics of management information and Web documents. A Web-based management user interface through embedded Web servers has many advantages such as ubiquity, platform independence and user-friendliness. In order to be truly useful, a Web-based management user interface must have a low development cost and a short development time. We provide effective integration mechanisms for each interface. We validate these mechanisms by implementing them in an Internet router.
13982146
Interaction Translation Methods for XML/SNMP Gateway
XML-based network management has been proposed as an alternative or to complement SNMP-based network management. But the XML-based network management does not yet provide a method to manage networks equipped with legacy SNMP agents in the integrated management system. This integrated management system must include an XML/SNMP gateway, which translates and relays messages between the XML-based manager and the SNMP agent. In this paper, we propose three methods for interaction translation in the gateway. First, we propose a DOM-based translation, which provides a method for XML-based manager to directly access management information through the standard DOM interfaces. Second, we propose an HTTP-based translation using URI extenstion with XPath and XQuery. Finally, we apply SOAP, which is accepted as a standard protocol for XML, and propose a translation method for the gateway to advertise the translation services to the manager using SOAP RPC. We also compare the advantages and disadvantages of the proposed translation methods.