Global Conformal Parameterization

title: Silhouette clipping
abstract: Approximating detailed with coarse, texture-mapped meshes results in polygonal silhouettes. To eliminate this artifact, we introduce silhouette clipping, a framework for efficiently clipping the rendering of coarse geometry to the exact silhouette of the original model. The coarse mesh is obtained using progressive hulls, a novel representation with the nesting property required for proper clipping. We describe an improved technique for constructing texture and normal maps over this coarse mesh. Given a perspective view, silhouettes are efficiently extracted from the original mesh using a precomputed search tree. Within the tree, hierarchical culling is achieved using pairs of anchored cones. The extracted silhouette edges are used to set the hardware stencil buffer and alpha buffer, which in turn clip and antialias the rendered coarse geometry. Results demonstrate that silhouette clipping can produce renderings of similar quality to high-resolution meshes in less rendering time.

title: A programming framework for quality-aware ubiquitous multimedia applications
abstract: Ubiquitous computing promises a computing environment that seamlessly and pervasively delivers applications to the user, despite changes of resources, devices, and locations. However, few ubiquitous multimedia applications (UMAs) exist up-to-date. One of the main reasons lies in the fact that it is difficult and error-prone to build a UMA which is mobile and deployable in different ubiquitous environments, and still provides acceptable application-specific Quality-of-Service (QoS) guarantees. In this paper, we present the design and implementation of a novel programming framework, called 'QCompiler" to address the challenges. The framework includes (1) a high-level application specification for the application developer to easily write a UMA with specific quality, mobility, and ubiquity supports, (2) a meta-data compilation, which provides automated consistency checks, translations, and substitutions, to relieve the application developer from dealing with complex programming related to quality, mobility, and ubiquity, (3) a binding, which prepares a quality-aware specification to be executable, in a specific deployment environment, and (4)a run-time meta-data execution, utilizing the meta-data compilation's results, to manage and control a quality-aware multimedia application. As a case study, we apply the programming framework to build a mobile Video-on-Demand (VoD) application. The experimental results show tradeoffs between easiness and flexibility to develop and deploy UMA, and overheads during UMA instantiation and adaptation.

title: On Composing Stream Applications in Peer-to-Peer Environments
abstract: Stream processing has become increasingly important as many emerging applications call for continuous real-time processing over data streams, such as voice-over-IP telephony, security surveillance, and sensor data analysis. In this paper, we propose a composable stream processing system for cooperative peer-to-peer environments. The system can dynamically select and compose stream processing elements located on different peers into user desired applications. We investigate multiple alternative approaches to composing stream applications: 1) global-state-based centralized versus local-state-based distributed algorithms for initially composing stream applications at setup phase. The centralized algorithm performs periodical global state maintenance while the distributed algorithm performs on-demand state collection. 2) Reactive versus proactive failure recovery schemes for maintaining composed stream applications during runtime. The reactive failure recovery algorithm dynamically recomposes a new stream application upon failures while the proactive approach maintains a number of backup compositions for failure recovery. We conduct both theoretical analysis and experimental evaluations to study the properties of different approaches. Our study illustrates the performance and overhead trade-offs among different design alternatives, which can provide important guidance for selecting proper algorithms to compose stream applications in cooperative peer-to-peer environments

title: Gene Network: Model, Dynamics and Simulation
abstract: A gene network is modeled as a dynamical random graph whose vertices and edges represent genes and gene-gene interactions, respectively. The network grows through three biological mechanisms: (1) gene duplication and loss; (2) gene-gene interaction adding and removing; and (3) genome duplication. The evolutionary dynamics of gene networks is discussed. It is shown that: (1) the vertex degree distribution (i.e., the distribution of the number of the gene-gene interactions per gene) always follows power laws and the power law exponents may be changed by genome duplications; and (2) the network degree distribution (i.e., the distribution of the total number of the gene-gene interactions in the network) has a complex behavior: If no genome duplication occurs, it follows a power law. If a genome duplication occurs, it may be away from the power law state. However, after a sufficient long evolutionary time, it approaches to a power law tail. The dynamics is confirmed by computer simulations. By allowing genome duplications, our model and dynamics (describing the dynamic behavior of gene networks) are more realistic than other previous ones (containing only static behavior).

title: DIVERGE: phylogeny-based analysis for functional-structural divergence of a protein family
abstract: DetectIng Variability in Evolutionary Rates among GEnes (DIVERGE) is a software system to study functional divergence of a protein family by detecting site-specific change in evolutionary rate using a multiple alignment of amino acid sequences for a given phylogenetic tree. The program first conducts a statistical test for site-specific rate shifts along the tree, and predicting candidate amino acid residues responsible for functional divergence based on posterior analysis. These results can then be mapped on the 3D protein structure if available.


AVAILABILITY
DIVERGE is available free of charge from http://xgu1.zool.iastate.edu/. Distribution packages for both Linux and Microsoft Windows operating systems are available, including manual and example files.

title: Optimal Component Composition for Scalable Stream Processing
abstract: Stream processing has become increasingly important with emergence of stream applications such as audio/video surveillance, stock price tracing, and sensor data analysis. A challenging problem is to provide optimal component composition in a distributed stream processing environment. The goal of optimal component composition is to achieve load balancing subject to multiple function, resource, and quality-of-service (QoS) constraints while composing stream applications. In this paper, we present an adaptive composition probing (ACP) approach to the problem. Different from previous work, ACP provides a new hybrid approach that combines distributed composition probing with coarse-grain global state management. Guided by the coarse-grain global state information, ACP selectively probes a subset of candidate components to discover an approximately optimal component composition. Further, ACP is self-tuning, which can adoptively adjust the number of probes to maintain a specified composition performance target (i.e., composition success rate) in a dynamic stream environment. While the optimal component composition problem is NP-hard, our ACP approach provides an adaptive polynomial approximation solution. We have conducted extensive simulation experiments to show the efficiency, scalability, and adaptability of the ACP approach by comparing with other alternative solutions